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Sample records for spontaneous fission activity

  1. Spontaneous fission of superheavy nuclei

    Indian Academy of Sciences (India)

    the Yukawa-plus-exponential potential. The microscopic shell and pairing corrections are obtained using the Strutinsky and BCS approaches and the cranking formulae yield the inertia tensor. Finally, the WKB method is used to calculate penetrabilities and spontaneous fission half-lives. Calculations are performed for the ...

  2. Spontaneous fission of the heaviest elements

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, D.C.

    1989-04-01

    Although spontaneous fission was discovered in /sup 238/U in 1940, detailed studies of the process were first made possible in the 1960's with the availability of milligram quantities of /sup 252/Cf. The advent of solid-state detectors made it possible to perform measurements of coincident fission fragments from even very short-lived spontaneous fission activities or those available in only very small quantities. Until 1971 it was believed that the main features of the mass and kinetic-energy distributions were essentially the same as those for thermal neutron-induced fission and that all low-energy fission proceeded via asymmetric mass division with total kinetic energies which could be derived by linear extrapolation from those of lighter elements. In 1971, measurements of /sup 257/Fm showed an increase in symmetric mass division with anomalously high TKE's. Subsequent experiments showed that in /sup 258/Fm and /sup 259/Fm, the most probable mass split was symmetric with very high total kinetic energy. Measurements for the heavier elements have shown symmetric mass distributions with both high and low total kinetic energies. Recent results for spontaneous fission properties of the heaviest elements are reviewed and compared with theory. 31 refs., 8 figs., 1 tab.

  3. Observation of new spontaneous fission activities from elements 100 to 105

    International Nuclear Information System (INIS)

    Somerville, L.P.

    1982-03-01

    Several new Spontaneous Fission (SF) activities have been found. No definite identification could be made for any of the new SF activities; however, half-lives and possible assignments to element-104 isotopes consistent with several cross bombardments include 257 Rf(3.8 s, 14% SF), 258 Rf(13 ms), 259 Rf(approx. 3 s, 8% SF), 260 Rf(approx. 20 ms), and 262 Rf(approx. 50 ms). The 80-ms SF activity claimed by the Dubna group for the discovery of element 104 ( 260 104) was not observed. A difficulty exists in the interpretation that 260 Rf is a approx. 20-ms SF activity: in order to be correct, for example, the SF activities with half-lives between 14 and 24 ms produced in the reactions 109- to 119-MeV 18 O + 248 Cm, 88- to 100-MeV 15 N + 249 Bk, and 96-MeV 18 O + 249 Cf must be other nuclides due to their large production cross sections, or the cross sections for production of 260 Rf must be enhanced by unknown mechanisms. Based on calculated total production cross sections a possible approx. 1% electron-capture branch in 258 Lr(4.5 s) to the SF emitter 258 No(1.2 ms) and an upper limit of 0.05% for SF branching in 254 No(55 s) were determined. Other measured half-lives from unknown nuclides produced in respective reactions include approx. 1.6 s ( 18 O + 248 CM), indications of a approx. 47-s SF activity (75-MeV 12 C + 249 Cf), and two or more SF activities with 3 s less than or equal to T/sub 1/2/ less than or equal to 60 s ( 18 O + 249 Bk). The most exciting conclusion of this work is that if the tentative assignments to even-even element 104 isotopes are correct, there would be a sudden change in the SF half-life systematics at element 104 which has been predicted theoretically and attributed to the disappearance of the second hump of the double-humped fission barrier

  4. Spontaneous fission of superheavy nuclei

    Indian Academy of Sciences (India)

    collaborators [1,2]. The importance of deformed valleys in the potential energy surfaces. (PES) is that they provide the most favoured fission channels for the decay of superheavy nuclei. For the dynamics study, one has to introduce the influence of mass tensor. We use the results from pairing calculations for the occupation ...

  5. Spontaneous fission of superheavy nuclei

    Indian Academy of Sciences (India)

    2015-08-02

    Aug 2, 2015 ... The macroscopic–microscopic method is extended to calculate the deformation energy and penetrability for binary nuclear configurations typical for fission processes. The deformed two-centre shell model is used to obtain single-particle energy levels for the transition region of two partially overlapped ...

  6. Spontaneous fission of superheavy nuclei

    Indian Academy of Sciences (India)

    2015-08-02

    Aug 2, 2015 ... ... nuclear configurations typical for fission processes. The deformed two-centre shell model is used to obtain single-particle energy levels for the transition region of two partially overlapped daughter and emitted fragment nuclei. The macroscopic part is obtained using the Yukawa-plus-exponential potential.

  7. Ternary fission of spontaneously fissile uranium isomers excited by neutrons

    International Nuclear Information System (INIS)

    Makarenko, V.E.; Molchanov, Y.D.; Otroshchenko, G.A.; Yan'kov, G.B.

    1989-01-01

    Spontaneously fissile isomers (SFI) of uranium were excited in the reactions 236,238 U(n,n') at an average neutron energy 4.5 MeV. A pulsed electrostatic accelerator and time analysis of the fission events were used. Fission fragments were detected by the scintillation method, and long-range particles from fission were detected by an ionization method. The relative probability of fission of nuclei through a spontaneously fissile isomeric state was measured: (1.30±0.01)·10 -4 ( 236 U) and (1.48±0.02)·10 -4 ( 238 U). Half-lives of the isomers were determined: 121±2 nsec (the SFI 236 U) and 267±13 nsec (the SFI 238 U). In study of the ternary fission of spontaneously fissile isotopes of uranium it was established that the probability of the process amounts to one ternary fission per 163±44 binary fissions of the SFI 236 U and one ternary fission per 49±14 binary fissions of the SFI 238 U. The substantial increase of the probability of ternary fission of SFI of uranium in comparison with the case of ternary fission of nuclei which are not in an isomeric state may be related to a special nucleon configuration of the fissile isomers of uranium

  8. Neutron angular distribution in plutonium-240 spontaneous fission

    Energy Technology Data Exchange (ETDEWEB)

    Marcath, Matthew J., E-mail: mmarcath@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States); Shin, Tony H.; Clarke, Shaun D. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States); Peerani, Paolo [European Commission at the Joint Research Centre, Ispra (Italy); Pozzi, Sara A. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States)

    2016-09-11

    Nuclear safeguards applications require accurate fission models that exhibit prompt neutron anisotropy. In the laboratory reference frame, an anisotropic neutron angular distribution is observed because prompt fission neutrons carry momentum from fully accelerated fission fragments. A liquid organic scintillation detector array was used with pulse shape discrimination techniques to produce neutron-neutron cross-correlation time distributions and angular distributions from spontaneous fission in a {sup 252}Cf, a 0.84 g {sup 240}Pu{sub eff} metal, and a 1.63 g {sup 240}Pu{sub eff} metal sample. The effect of cross-talk, estimated with MCNPX-PoliMi simulations, is removed from neutron-neutron coincidences as a function of the angle between detector pairs. Fewer coincidences were observed at detector angles near 90°, relative to higher and lower detector angles. As light output threshold increases, the observed anisotropy increases due to spectral effects arising from fission fragment momentum transfer to emitted neutrons. Stronger anisotropy was observed in Cf-252 spontaneous fission prompt neutrons than in Pu-240 neutrons. - Highlights: • Pu-240 prompt fission fast-neutron anisotropy was quantified for the first time. • MCNPX-PoliMi and MPPost codes were used to remove cross-talk neutron detections from experiment results. • Cf-252 spontaneous fission neutrons were found to be more anisotropic than Pu-240 neutrons.

  9. Spontaneous fission of neutron-rich superheavy nuclei

    International Nuclear Information System (INIS)

    Gherghiescu, R.A.

    1997-01-01

    Neutron-rich isotopes of the superheavy elements 112, 114, and 116 have been studied for neutron numbers 184, 186, and 188. The spontaneous fission life-time calculations have been performed within the WKB method. Large values have been obtained due to the proton-shell closure 114. The maximum of the fission lifetime occurs for the double-magic superheavy nucleus (114,184). (author)

  10. Neutron angular distribution in plutonium-240 spontaneous fission

    Science.gov (United States)

    Marcath, Matthew J.; Shin, Tony H.; Clarke, Shaun D.; Peerani, Paolo; Pozzi, Sara A.

    2016-09-01

    Nuclear safeguards applications require accurate fission models that exhibit prompt neutron anisotropy. In the laboratory reference frame, an anisotropic neutron angular distribution is observed because prompt fission neutrons carry momentum from fully accelerated fission fragments. A liquid organic scintillation detector array was used with pulse shape discrimination techniques to produce neutron-neutron cross-correlation time distributions and angular distributions from spontaneous fission in a 252Cf, a 0.84 g 240Pueff metal, and a 1.63 g 240Pueff metal sample. The effect of cross-talk, estimated with MCNPX-PoliMi simulations, is removed from neutron-neutron coincidences as a function of the angle between detector pairs. Fewer coincidences were observed at detector angles near 90°, relative to higher and lower detector angles. As light output threshold increases, the observed anisotropy increases due to spectral effects arising from fission fragment momentum transfer to emitted neutrons. Stronger anisotropy was observed in Cf-252 spontaneous fission prompt neutrons than in Pu-240 neutrons.

  11. Insights into nuclear structure and the fission process from spontaneous fission

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, J.H.; Butler-Moore, K.; Ramayya, A.V. [Vanderbilt Univ., Nashville, TN (United States)] [and others

    1993-12-31

    The {gamma}-rays emitted following spontaneous and induced fission are rich sources of information about the structure of neutron-rich nuclei and about the fission process itself. The study of spontaneous fissioning isotopes with large Ge detector arrays are providing a wealth of such information as seen, for example, in recent reports. In this paper we present some of our most recent results on nuclear structure studies and conclusions on the fission process itself. In our work, we have employed in spontaneous fission, a triple gamma coincidence study for the first time and a high resolution, X-ray detector-{gamma}-coincidence study. These data provide powerful ways of separating the gamma rays which belong to a particular nucleus. The triple coincidence technique was used to uniquely identify the levels in {sup 136}Te and higher spin states in its N=84 isotones, {sup 138}Xe and {sup 140}Ba{sup 171}. Some other examples of the level structures observed in the low and high mass partners are presented, including a detailed analysis of the backbending of the moment of inertia in {sup 112,114,116}Pd. Finally, we present the first examples of how our analysis allows one to extract a detailed picture of the dependence of the angular momentum on the mass and atomic numbers of the fission fragments and of the long-sought neutron multiplicity distribution from zero-n to ten-n as a function of the charge and mass asymmetry.

  12. Study of spontaneous fission lifetimes using nuclear density functional theory

    Directory of Open Access Journals (Sweden)

    Sadhukhan Jhilam

    2013-12-01

    Full Text Available The spontaneous fission lifetimes have been studied microscopically by minimizing the collective action integral in a two-dimensional collective space of quadrupole moments (Q20, Q22 representing elongation and triaxiality. The microscopic collective potential and inertia tensor are obtained by solving the self-consistent Hartree-Fock-Bogoliubov (HFB equations with the Skyrme energy density functional and mixed pairing interaction. The mass tensor is computed within the perturbative Adiabatic Time-Dependent HFB (ATDHFB approach in the cranking approximation. The dynamic fission trajectories have been obtained by minimizing the collective action using two different numerical techniques. The values of spontaneous fission lifetimes obtained in this way are compared with the static results.

  13. Evaluation of mass distribution data from 252Cf spontaneous fission

    International Nuclear Information System (INIS)

    Liu Tingjin

    2003-01-01

    The mass distribution data of 252 Cf spontaneous fission were evaluated based on 7 sets of available experimental data. The measured data were corrected for the standards and γ intensity used by using the new evaluated ones. The errors were made necessary adjusting. The evaluated experimental data were fitted with spline function without any restriction and with symmetric restriction. These two sets of fit data were recommended as reference data of the mass distribution of 252 Cf spontaneous fission. The errors of the recommended data were considerably reduced comparing with the measured ones. The light and heavy peaks are not completely symmetric. Also there are fine structures on the right side of the light peak at A=109-111 and left side of the heavy peak at A=137-139. These should be paid attention and studied further. (author)

  14. High energy γ rays from 252Cf spontaneous fission

    Science.gov (United States)

    Hofman, D. J.; Back, B. B.; Montoya, C. P.; Schadmand, S.; Varma, R.; Paul, P.

    1993-03-01

    The spontaneous fission decay of 252Cf has been analyzed in a statistical model with emphasis on describing recently reported high energy γ-ray spectra. An enhanced γ emission in the range from 3 to 10 MeV which is observed for nearly symmetric mass splits is readily understood as a result of the different fragment excitation energies. The model includes a viscous motion to the scission point with the possibility of prescission γ emission. It was found that even with saddle-to-scission times of τscneutron multiplicities, prescission γ rays are overwhelmed by fragment γ rays. Thus, the recently reported strong angular anisotropy of γ rays in the range Eγ=8-12 MeV is unexplained within the present understanding of the fission process.

  15. Prompt neutron spectrum of the spontaneous fission of californium-252

    International Nuclear Information System (INIS)

    Zamyatnin, Yu.S.; Kroshkin, N.I.; Korostylev, V.A.; Nefedov, V.N.; Ryazanov, D.K.; Starostov, B.I.; Semenov, A.F.

    1976-01-01

    The californium-252 spontaneous fission neutron spectrum was measured in the energy range of 0.01 to 10 MeV by the time-of-flight technique using various neutron detectors. The measurements of 252 Cf neutron spectrum at energies of 0.01 to 5 MeV were performed as a function of fission fragment kinetic energy. The mean neutron spectrum energy in the range of 0.7 to 10 MeV was found from the results of measurements. The irregularity in the 252 Cf neutron spectrum in the neutron energy range of less than 0.7 MeV compared to theoretical values is discussed. The mechanism of 252 Cf neutron emission is also discussed on the basis of neutron yield angle measurements. 12 references

  16. Competition between spontaneous fission ternary fission cluster decay and alpha decay in the super heavy nuclei of Z = 126

    Science.gov (United States)

    Manjunatha, H. C.; Sowmya, N.

    2018-01-01

    Super heavy nuclei may decay through the different decay modes such as spontaneous fission, ternary fission and cluster decay. There is a need to study the different decay modes such as spontaneous fission, ternary fission and cluster decay of super heavy nuclei. We studied the spontaneous fission, ternary fission and cluster decay of predicted isotopes of super heavy nuclei for Z = 126 and compared with that of alpha decay. This enables to study the competition between spontaneous fission, ternary fission, cluster decay and alpha decay in the super heavy nuclei of Z = 126. The comparison of half lives for different decay modes reveals that alpha decay is having smaller half lives than the other studied decay modes. A detailed study of branching ratio of alpha decay with respect to other decay modes also confirms that alpha decay is most dominant decay mode for the super heavy nuclei 318126, 319126, 320126 and 323-326126 and hence these nuclei can be detected through the alpha decay mode only.

  17. Maximum permissible concentration (MPC) values for spontaneously fissioning radionuclides

    International Nuclear Information System (INIS)

    Ford, M.R.; Snyder, W.S.; Dillman, L.T.; Watson, S.B.

    1976-01-01

    The radiation hazards involved in handling certain of the transuranic nuclides that exhibit spontaneous fission as a mode of decay were reaccessed using recent advances in dosimetry and metabolic modeling. Maximum permissible concentration (MPC) values in air and water for occupational exposure (168 hr/week) were calculated for 244 Pu, 246 Cm, 248 Cm, 250 Cf, 252 Cf, 254 Cf, /sup 254m/Es, 255 Es, 254 Fm, and 256 Fm. The half-lives, branching ratios, and principal modes of decay of the parent-daughter members down to a member that makes a negligible contribution to the dose are given, and all daughters that make a significant contribution to the dose to body organs following inhalation or ingestion are included in the calculations. Dose commitments for body organs are also given

  18. Spectroscopy of neutron-rich nuclei populated in the spontaneous fission of 252Cf and 248Cm

    International Nuclear Information System (INIS)

    Smith, A. G.; Simpson, G. S.; Billowes, J.; Durell, J. L.; Phillips, W. R.; Dagnall, P. J.; Freeman, S. J.; Leddy, M.; Roach, A. A.; Smith, J. F.

    1999-01-01

    In this paper we present research that has been carried out using the Euroball and Eurogam arrays to detect γ rays emitted from spontaneously fissioning 248 Cm and 252 Cf. The paper focuses on three sub-areas of current activity, namely, the measurement of yields of secondary fragment pairs, the measurement of state lifetimes at around spin 10, and recent measurements of g-factors of excited states in fission fragments. (c) 1999 American Institute of Physics

  19. Characterization of the LISOL laser ion source using spontaneous fission of 252Cf

    OpenAIRE

    Kudryavtsev, Yuri; Cocolios, Thomas Elias; Gentens, Johnny; Ivanov, Oleg; Huyse, Marc; Pauwels, Dieter; Sawicka, Maria; Sonoda, Tetsu; Van den Bergh, Paul; Van Duppen, Piet

    2008-01-01

    A spontaneous fission Californium-252 source was placed inside a gas cell in order to characterize the LISOL laser ion source. The fission products from 252Cf are thermalized and neutralized in the plasma created by energetic particles. Two-step selective laser ionization is applied to produce purified beams of radioactive isotopes. The survival of fission products in a single charge state has been studied in argon as a buffer gas for different elements.

  20. Characterization of the LISOL laser ion source using spontaneous fission of 252Cf

    Science.gov (United States)

    Kudryavtsev, Yu.; Cocolios, T. E.; Gentens, J.; Ivanov, O.; Huyse, M.; Pauwels, D.; Sawicka, M.; Sonoda, T.; Van den Bergh, P.; Van Duppen, P.

    2008-10-01

    A spontaneous fission Californium-252 source was placed inside a gas cell in order to characterize the LISOL laser ion source. The fission products from 252Cf are thermalized and neutralized in the plasma created by energetic particles. Two-step selective laser ionization is applied to produce purified beams of radioactive isotopes. The survival of fission products in a single charge state has been studied in argon as a buffer gas for different elements.

  1. STUDY OF THE GAMMA EMISSION PROBABILITY ACCOMPANYING THE SPONTANEOUS FISSION OF CF-252

    NARCIS (Netherlands)

    VANDERPLOEG, H; LAURENS, CR; BACELAR, JCS; BUDA, A; GAARDHOJE, JJ; VANTHOF, G; KALANTARNAYESTANAKI, N; VANDERWOUDE, A; ZELAZNY, Z

    1994-01-01

    A study of the gamma emission accompanying the spontaneous fission process of Cf-252 has been performed. The photon emission probability between 3 and 70 MeV and its angular dependence with respect to the fission direction were measured. These measurements were performed as a function of the mass

  2. Yields of correlated fragment pairs and neutron multiplicity in spontaneous fission of {sup 242}Pu

    Energy Technology Data Exchange (ETDEWEB)

    Veselsky, M.; Kliman, J.; Morhaccaron, M. [Institute of Physics of Slovak Academy of Sciences, Dubravska 9, 84228 Bratislava (Slovakia); Ramayya, A.V.; Kormicki, J.; Daniel, A.V. [Physics Department, Vanderbilt University, Nashville (United States)] Rasmussen, J.O. [Lawrence Berkeley National Laboratory, Berkeley (United States)] Stoyer, M.A. [Lawrence Livermore National Laboratory, Livermore (United States); Daniel, A.V.; Popeko, G.S.; Oganessian, Yu. Ts. [Joint Institute for Nuclear Research, Dubna (Russia)] Greiner, W. [Institut fur Theoretische Physik, J. W. Goethe Universitaet, Frankfurt a. M. (Germany); Aryaeinejad, R. [Idaho National Engineering Laboratory, Idaho Falls (United States)

    1998-10-01

    Yields of correlated fragment pairs were obtained in spontaneous fission of {sup 242}Pu. Charge, mass and neutron multiplicity distributions of fragment pairs were determined and compared to available data. The yield of cold fission without neutron emission was determined to about 10{percent} for the set of observed correlated fragment pairs. {copyright} {ital 1998 American Institute of Physics.}

  3. Spontaneous fission half-lives of heavy and superheavy nuclei within a generalized liquid drop model

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Xiaojun [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Zhang, Hongfei, E-mail: zhanghongfei@lzu.edu.cn [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Royer, G. [Laboratoire Subatech, UMR: IN2P3/CNRS-Université-Ecole des Mines, 4 rue A. Kastler, 44 Nantes (France); Li, Junqing [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000 (China)

    2013-05-15

    We systematically calculate the spontaneous fission half-lives for heavy and superheavy nuclei between U and Fl isotopes. The spontaneous fission process is studied within the semi-empirical WKB approximation. The potential barrier is obtained using a generalized liquid drop model, taking into account the nuclear proximity, the mass asymmetry, the phenomenological pairing correction, and the microscopic shell correction. Macroscopic inertial-mass function has been employed for the calculation of the fission half-life. The results reproduce rather well the experimental data. Relatively long half-lives are predicted for many unknown nuclei, sufficient to detect them if synthesized in a laboratory.

  4. The measurement of prompt neutron spectrum in spontaneous fission of {sup 244}Cm

    Energy Technology Data Exchange (ETDEWEB)

    Batenkov, O.I.; Boykov, G.S.; Drapchinsky, L.V.; Majorov, M.Ju.; Trenkin, V.A. [V.G. Khlopin Radium Inst., Saint Petersburg (Russian Federation)

    1997-03-01

    Under the Program of Measurements of Prompt Fission Neutron Spectra of Minor Actinides for Transmutation Purposes the integral neutron spectrum in spontaneous fission of {sup 244}Cm has been measured by the time-of-flight method in the energy range of 0.1-15 MeV relative to the standard neutron spectrum in {sup 252}Cf spontaneous fission. Essential attention was paid to revealing of possible systematic errors. It is shown, that the {sup 244}Cm spectrum shape may be well described by using Mannhart evaluation with appropriate parameter of Maxwell temperature T{sub M} = 1.37 MeV. (author)

  5. Competition between α-decay and spontaneous fission for superheavy nuclei

    Science.gov (United States)

    Bao, X. J.; Guo, S. Q.; Zhang, H. F.; Xing, Y. Z.; Dong, J. M.; Li, J. Q.

    2015-08-01

    The α-decay half-lives of recently synthesized superheavy nuclei (SHN) are investigated by employing a unified fission model (UFM) and Royer’s analytical formula (2000 J. Phys. G: Nucl. Part. Phys. 26 1149). The good agreement with the experimental data indicates the UFM and the analytical formula are useful tools to investigate these α-decays. A modified formula is proposed for determining the spontaneous fission half-lives based on Swiatecki’s formula, including the microscopic shell correction and isospin effect.The spontaneous fission half-lives for heavy and SHN in regions from Th to Fl are calculated systematically. Experimental data are well reproduced by the modified Swiatecki formula. The competition between α-decay and spontaneous fission is analyzed in detail and the decay modes are predicted for the unknown cases.

  6. Improved calculation of the prompt fission neutron spectrum from the spontaneous fission of /sup 252/Cf: Preliminary results

    International Nuclear Information System (INIS)

    Madland, D.G.

    1988-01-01

    An improved calculation is presented for the prompt fission neutron spectrum N(E) from the spontaneous fission of /sup 252/Cf. In this calculation the fission-spectrum model of Madland and Nix is used, but with several improvements leading to a physically more accurate representation of the spectrum. Specifically, the contributions to N(E) from the entire fission-fragment mass and charge distributions will be calculated instead of calculating on the basis of a seven- point approximation to the peaks of these distributions as has been done in the past. Therefore, values of the energy release in fission, fission-fragment kinetic energy, and compound nucleus cross section for the inverse process will be considered on a point-by-point basis over the fragment yield distributions instead of considering averages of these quantities over the peaks of the distributions. Preliminary results will be presented and compared with a measurement, an earlier calculation, and a recent evaluation of the spectrum. 14 refs., 4 figs

  7. Influence of the cosmic-ray induced fission tracks on the fission track of extraterrestric minerals via the 238U spontaneous fission

    International Nuclear Information System (INIS)

    Damm, G.; Thiel, K.

    1977-01-01

    The age determined by counting fission tracks of lunar and meteorite materials is obviously falsified by additional fission track parts not to be accounted for by the spontaneous fission of uranium 238. For this p and n induced fissions of U, Th and other hreavy elements through the cosmic radiation come into consideration. In order to determine the possible part of such interference factors, a simulation experiment at the proton synchrocycloton (CERN, Geneva) has been carried out and independently of this, the production rates for the p and n induced U, Th, Bi, Pb and Au in the surface-near regolith layers of the moon were calculated. It could be seen that the irradiation age as well as the spacial distribution of the heavy metals in the samples to be dated must be considered. (RB) [de

  8. Measurement of the fission yields of selected prompt and decay fission product gamma-rays of spontaneously fissioning 252Cf and 244Cm

    International Nuclear Information System (INIS)

    Reber, E.L.; Gehrke, R.J.; Aryaeinejad, R.; Hartwell, J.K.

    2005-01-01

    Gamma-ray spectrometry measurements have been made of the fission yields of selected γ -rays emitted by the spontaneously fissioning isotopes 252 Cf and 244 Cm. The measured γ-rays were selected based on their relative abundance in the spectrum and their freedom from interference or, in a few instances, ease of interference correction. From these data and the cumulative and independent yield data of England and Rider, those γ-rays that are primarily produced by radioactive decay, as opposed to direct yield, were converted into the decays per spontaneous fission expressed in percent and compared to cumulative yield values of England and Rider. For those γ-rays whose production is dominated by direct (independent) yield, the ratio of γ-rays per spontaneous fission is reported. The γ-ray yield can be compared to the independent yield values of England and Rider when 100% of the direct feeding passes through the γ-ray. In those cases where both cumulative and independent yields contribute to the observed γ-ray emission rate, a direct comparison is not possible but a method to quantify the contribution from each is proposed. (author)

  9. Asymmetry of mass and charge division in spontaneous fission

    International Nuclear Information System (INIS)

    Chakraborty, P.P.; Iyer, M.R.; Ganguly, A.K.

    The order-disorder model (ODM) has been used to explain asymmetry of mass and charge division and related phenomena in fission. According to this model the fission process involves two steps consisting of charge polarisation into two impending fragments with beta stable neutron numbers and subsequent distribution of the balance neutrons between the two. The statistics developed on the principle of equal a priori probability of all charge polarisation is used. The shell effects comes into play only in deciding stable neutron number for the charges. The total isotopic yield distribution for a number of fission reactions are presented. These show asymmetry in the actinide region which reduces with increasing mass/charge of the fissioning nuclide and bunching of the higher z peaks. The mass yields obtained therefrom for a number of fission reactions are compared with experimental results. Though there is general agreement with experimental data, the peaks of the distributions are slightly shifted away from the symmetric point and the distributions are somewhat narrower. Charge distribution parameters obtained from these results are also presented. The model predicts preference of asymmetric division for super heavy nuclides. (author)

  10. Angular correlations in the prompt neutron emission in spontaneous fission of 252Cf

    OpenAIRE

    Kopatch Yuri; Chietera Andreina; Stuttgé Louise; Gönnenwein Friedrich; Mutterer Manfred; Gagarski Alexei; Guseva Irina; Dorvaux Olivier; Hanappe Francis; Hambsch Franz-Josef

    2017-01-01

    An experiment aiming at the detailed investigation of angular correlations in the neutron emission from spontaneous fission of 252Cf has been performed at IPHC Strasbourg using the angle-sensitive double ionization chamber CODIS for measuring fission fragments and a set of 60 DEMON scintillator counters for neutron detection. The main aim of the experiment is to search for an anisotropy of neutron emission in the center-of-mass system of the fragments. The present status of the data analysis ...

  11. Prompt gamma-ray multiplicity distributions in spontaneous fission of 252Cf

    International Nuclear Information System (INIS)

    Varma, R.; Mehta, G.K.; Choudhury, R.K.; Kapoor, S.S.; Nayak, B.K.; Ramamurthy, V.S.

    1991-01-01

    The mean and the standard deviation of the prompt gamma-ray multiplicity distribution in spontaneous fission of 252 Cf have been measured as a function of the charge ratio of the fission fragment pairs. While the variation of the mean multiplicity as a function of charge ratio is found to be nearly structureless, the standard deviation exhibits considerable variations. A statistical model analysis of the data was carried out to determine the contribution of the initial spin distribution widths of the fission fragments to the observed standard deviation of the gamma-ray multiplicity distribution

  12. Progress in fission product nuclear data. Information about activities in the field of measurements and compilations/evaluations of fission product nuclear data (FPND)

    International Nuclear Information System (INIS)

    Lammer, G.

    1978-07-01

    This is the fourth issue of a report series on Fission Product Nuclear Data (FPND) which is published by the Nuclear Data Section (NDS) of the International Atomic Energy Agency (IAEA). The purpose of this series is to inform scientists working on FPND, or using such data, about all activities in this field which are planned, ongoing, or have recently been completed. The main part of this report consists of unaltered original contributions which the authors have sent to IAEA/NDS. The types of activities being included in this report are measurements, compilations and evaluations of: Fission product yields (neutron induced and spontaneous fission); neutron reaction cross sections of fission products; data related to the radioactive decay of fission products; delayed neutron data of fission products; and lumped fission product data (decay heat, absorption etc.)

  13. Fission fragment mass and total kinetic energy distributions of spontaneously fissioning plutonium isotopes

    Science.gov (United States)

    Pomorski, K.; Nerlo-Pomorska, B.; Bartel, J.; Schmitt, C.

    2018-03-01

    The fission-fragment mass and total kinetic energy (TKE) distributions are evaluated in a quantum mechanical framework using elongation, mass asymmetry, neck degree of freedom as the relevant collective parameters in the Fourier shape parametrization recently developed by us. The potential energy surfaces (PES) are calculated within the macroscopic-microscopic model based on the Lublin-Strasbourg Drop (LSD), the Yukawa-folded (YF) single-particle potential and a monopole pairing force. The PES are presented and analysed in detail for even-even Plutonium isotopes with A = 236-246. They reveal deep asymmetric valleys. The fission-fragment mass and TKE distributions are obtained from the ground state of a collective Hamiltonian computed within the Born-Oppenheimer approximation, in the WKB approach by introducing a neck-dependent fission probability. The calculated mass and total kinetic energy distributions are found in good agreement with the data.

  14. Microscopic Phase-Space Exploration Modeling of ^{258}Fm Spontaneous Fission.

    Science.gov (United States)

    Tanimura, Yusuke; Lacroix, Denis; Ayik, Sakir

    2017-04-14

    We show that the total kinetic energy (TKE) of nuclei after the spontaneous fission of ^{258}Fm can be well reproduced using simple assumptions on the quantum collective phase space explored by the nucleus after passing the fission barrier. Assuming energy conservation and phase-space exploration according to the stochastic mean-field approach, a set of initial densities is generated. Each density is then evolved in time using the nuclear time-dependent density-functional theory with pairing. This approach goes beyond the mean-field theory by allowing spontaneous symmetry breaking as well as a wider dynamical phase-space exploration leading to larger fluctuations in collective space. The total kinetic energy and mass distributions are calculated. New information on the fission process: fluctuations in scission time, strong correlation between TKE and collective deformation, as well as prescission particle emission, are obtained. We conclude that fluctuations of the TKE and mass are triggered by quantum fluctuations.

  15. Study of the shielding for spontaneous fission sources of Californium-252

    International Nuclear Information System (INIS)

    Davila R, I.

    1991-06-01

    A shielding study is made to attenuate, until maximum permissible levels, the neutrons radiation and photons emitted by spontaneous fission coming from a source of Californium-252. The compound package by a database (Library DLC-23) and the ANISNW code is used, in it version for personal computer. (Author)

  16. Gamma ray transitions in de-excitation of 252Cf spontaneous fission fragments

    International Nuclear Information System (INIS)

    Khan, N.A.; Rashid, K.; Ahmad, M.; Qureshi, I.E.; Alam, G.D.; Ali, A.; Bhatti, N.; Horsch, F.

    1983-11-01

    Gamma rays in the range from 60 keV to 730 keV have been observed following the spontaneous fission of 252 Cf, with high resolution Ge(Li) detector, full width at half maximum (FWHM) of 700 eV at 122 keV, in coincidence with the two fission fragments observed with surface barrier detectors. A total number of 18, 636, 549 events were recorded over a run period of about 150 hours stretching over three weeks. The events were sorted to generate gamma ray spectra belonging to 2 amu intervals gamma of the fragment masses and 6 MeV intervals of the total kinetic energy released. Some of the prominent gamma lines belonging to various masses of the fission fragments have been identified. For some gamma lines, the intensities have been evaluated as a function of the total kinetic energy of the fission fragments. (authors)

  17. Dispersions and correlations of the distributions of products of 252Cf spontaneous fission

    International Nuclear Information System (INIS)

    Vidyakin, G.S.; Vyrodov, V.N.; Gurevich, I.I.; Kirillov, B.F.; Kozlov, Y.V.; Martem'yanov, V.P.; Sukhotin, S.V.; Tarasenkov, V.G.; Khakimov, S.K.

    1982-01-01

    We report the results of two experiments on study of the dispersions and correlations of the distributions of products of the spontaneous fission of 252 Cf. In each experiment about 10 8 fissions were recorded with simultaneous measurement of the number of neutrons produced and in one case the fragment kinetic energy and in the other case the energy of the prompt #betta# rays. The quantities obtained were the probabilities of production of a given number of neutrons per fission, the dispersions of the distributions of the number of neutrons produced and of the fragment kinetic energy, and the dependence of the average #betta#-ray energy and the average fragment kinetic energy on the number of neutrons produced. A calculation is made of the spectrum of the total energy carried away by fragments and neutrons, and its dispersion is determined. An estimate of the total energy release in the 252 Cf fission process is made

  18. Measurements of the effective range of fission fragments in UO2 and the disintegration constant for spontaneous fission of 238U

    International Nuclear Information System (INIS)

    Spaggiari, E.R.V.

    1978-01-01

    The results of measuments of the disintegration constant for spontaneous fission in 238 U are presented, with a discussion on the method used for the detection of fission tracks in muscovite mica. Samples of muscovite mica sandwiched between two natural uranium dioxide cylinders were irradiated with fragments of spontaneous fission and the etched tracks counted with projetion optical microscope. The effective thickness of the UO 2 layer which contributed to the observed tracks was measured through irradiation of mica samples, in contact with the UO 2 cylinder with 14,0 MeV neutrons from a (d,t) reaction. (Author) [pt

  19. Angular correlations in the prompt neutron emission in spontaneous fission of 252Cf

    Science.gov (United States)

    Kopatch, Yuri; Chietera, Andreina; Stuttgé, Louise; Gönnenwein, Friedrich; Mutterer, Manfred; Gagarski, Alexei; Guseva, Irina; Dorvaux, Olivier; Hanappe, Francis; Hambsch, Franz-Josef

    2017-09-01

    An experiment aiming at the detailed investigation of angular correlations in the neutron emission from spontaneous fission of 252Cf has been performed at IPHC Strasbourg using the angle-sensitive double ionization chamber CODIS for measuring fission fragments and a set of 60 DEMON scintillator counters for neutron detection. The main aim of the experiment is to search for an anisotropy of neutron emission in the center-of-mass system of the fragments. The present status of the data analysis and the full Monte-Carlo simulation of the experiment are reported in the present paper.

  20. Angular correlations in the prompt neutron emission in spontaneous fission of 252Cf

    Directory of Open Access Journals (Sweden)

    Kopatch Yuri

    2017-01-01

    Full Text Available An experiment aiming at the detailed investigation of angular correlations in the neutron emission from spontaneous fission of 252Cf has been performed at IPHC Strasbourg using the angle-sensitive double ionization chamber CODIS for measuring fission fragments and a set of 60 DEMON scintillator counters for neutron detection. The main aim of the experiment is to search for an anisotropy of neutron emission in the center-of-mass system of the fragments. The present status of the data analysis and the full Monte-Carlo simulation of the experiment are reported in the present paper.

  1. Multiplicity and correlated energy of gamma rays emitted in the spontaneous fission of Californium-252

    International Nuclear Information System (INIS)

    Brunson, G.S. Jr.

    1982-06-01

    An array of eight high-speed plastic scintillation detectors has been used to infer a mathematical model for the emission multipliciy of prompt gammas in the spontaneous fission of 252 Cf. Exceptional time resolution and coincidence capability permitted the separation of gammas from fast neutrons over a flight path of approximately 10 cm. About 20 different distribution models were tested. The average energy of the prompt gammas is inversely related to the number emitted; however, this inverse relationship is not strong and the total gamma energy does increase with increasing gamma number. An extension of the experiment incorporated a lithium-drifted germanium gamma spectrometer that resolved nearly 100 discrete gammas associated with fission. Of these gammas, some were preferentially associated with fission in which few gammas were emitted. Certain others were more frequent when many gammas were emitted. Results are presented

  2. Spontaneous-fission half-lives for even nuclei with Z> or =92

    International Nuclear Information System (INIS)

    Randrup, J.; Larsson, S.E.; Moller, P.; Nilsson, S.G.; Pomorski, K.; Sobiczewski, A.

    1976-01-01

    The spontaneous-fission process for doubly even nuclei with Z> or =92 is studied in a semiempirical WKB framework. One-dimensional fission barrier potentials are established from theoretical deformation-energy surfaces based on the droplet model and the modified-oscillator model. The effects of axial asymmetry as well as reflection asymmetry have been taken into account. Macroscopic (irrotational flow) inertial-mass functions and, alternatively, microscopic (cranking model) inertial mass parameters have been employed for the calculation of the fission half-lives. With one over-all normalization parameter it is possible to fit the experimental half-lives to within a factor of 20 on the average. The resulting effective inertial-mass functions are used to estimate the stability of the transactinide elements. Only minor differences with previous estimates for the r process and superheavy nuclei are encountered

  3. Study of ternary and quaternary spontaneous fission of 252Cf with the NESSI detector

    International Nuclear Information System (INIS)

    Tishchenko, V.G.; Jahnke, U.; Herbach, C.M.; Hilscher, D.

    2002-11-01

    Ternary and quaternary spontaneous decay of 252 Cf was studied with the NESSI detector, a combination of two 4π detectors for charged particles, neutrons and γ-rays. The applied method of particle identification by measuring the energies and relative time-of-flights of the decay products is shown to be very effective for the study of rare decay modes. The energy and angular distributions of the decay products, the associated neutron multiplicities, the total energy of the prompt γ-radiation as well as correlations between the various observables were measured for the first time in a single full-scale experiment. The characteristics of ternary fission known from previous investigations are confirmed in the frame of a methodically independent experiment. Preliminary estimates of the quaternary fission yield are presented. An attempt is made to determine the mechanism of quaternary fission. (orig.)

  4. Correlated spins of complementary fragment pairs in the spontaneous fission of 252Cf

    International Nuclear Information System (INIS)

    Smith, A. G.; Simpson, G. S.; Billowes, J.; Dagnall, P. J.; Durell, J. L.; Freeman, S. J.; Leddy, M.; Phillips, W. R.; Roach, A. A.; Smith, J. F.

    1999-01-01

    A study of the γ-ray decay of low-lying excited states in fragments produced in the spontaneous fission of 252 Cf has revealed a significant correlation between the angles of emission of the 2 1 + →0 1 + transitions of complementary fragment pairs. Calculations of the amount of dealignment that is needed to reproduce the measured a 2 values, and a comparison with the results of previous fragment-γ angular distribution measurements, suggests that at scission there may be significant population of m≠0 substates associated with the projection of the fragment spin vector on the fission axis. Fragments from the spontaneous fission of 248 Cm emit 2 1 + →0 1 + γ rays that show markedly reduced interfragment correlations, suggesting that either a larger role is played by the relative angular momentum of the fragments, or that the dealignment introduced by the neutron emission and statistical γ decay to the 2 1 + state is larger in 248 Cm than 252 Cf fission. (c) 1999 The American Physical Society

  5. Extensions to COGEND for ENDF/B-V output of spontaneous fission decay data

    International Nuclear Information System (INIS)

    Tobias, A.

    1978-06-01

    The computer code COGEND, used to produce ENDF/B-IV or -V format nuclear decay scheme data, has been modified in order to extend its range of application. Details are given of the additional facilities which permit the handling of spontaneous fission decay data including any associated continuous spectra. In order to accommodate these additional features it is necessary to increase the core region by 4 kilobytes. (author)

  6. 252Cf spontaneous prompt fission neutron spectrum measured at 0 degree and 180 degree relative to the fragment motion

    International Nuclear Information System (INIS)

    Bao Shanglian; Liu Jinquan; Batenkov, O.I.; Blinov, M.V.; Smirnov, S.N.

    1994-09-01

    The 252 Cf spontaneous prompt fission neutron spectrum at 0 degree and 180 degree relative to the motion direction of corresponding fission fragments was measured. High angular resolution for fragment measurements and high energy resolution for neutron measurements were obtained using multi-parameter TOF spectrometer. The results showed that there is a symmetric distribution of 'forward' and 'backward' for low energy in C.M.S. neutrons, which was an evidence of nonequilibrium neutrons existed in fission process

  7. Microscopic description of the competition between spontaneous fission and α -decay in neutron-rich Ra, U and Pu nuclei

    International Nuclear Information System (INIS)

    Rodríguez-Guzmán, R; Robledo, L M

    2017-01-01

    Constrained mean-field calculations, based on the Gogny-D1M energy density functional, have been carried out to describe fission in Ra, U and Pu nuclei with neutron number 144 ≤ N ≤ 176. Fission paths, collective masses and zero-point quantum vibrational and rotational corrections are used to compute the spontaneous fission half-lives. We also pay attention to isomeric states along the considered fission paths. Alpha decay half-lives have also been computed using a parametrization of the Viola-Seaborg formula. Though there exists a strong variance of the predicted fission rates with respect to the details involved in their computation a robust trend is obtained indicating, that with increasing neutron number fission dominates over α -decay. Our results also suggest that a dynamical treatment of pairing correlations is required within the microscopic studies of the fission process in heavy nuclear systems. (paper)

  8. Decay of Plutonium isotopes via spontaneous and heavy-ion induced fission paths

    Science.gov (United States)

    Sharma, Kanishka; Sawhney, Gudveen; Sharma, Manoj K.; Gupta, Raj K.

    2018-04-01

    Based on the collective clusterization approach, we have extended our earlier study on α-decay, exotic cluster-decay, and heavy particle radioactivity, to the phenomenon of spontaneous fission (SF) in the ground-state (g.s.) decays of even mass 234-246Pu parents. The calculations for the SF half-lives of these Pu-isotopes have been made within the framework of preformed cluster model (PCM), both for spherical as well as β2-deformed choices of shapes, and a comparison is made with the relevant available experimental data, which prefer spherical shapes. The importance of the orientation degree of freedom (hot compact or cold elongated configurations) is also explored. Next, in order to look for the exclusive role of heavy-ion induced fission, the dynamics of 6He + 238U reaction forming 244Pu* is studied over the center of mass energy range of E c . m . = 15.0- 28.8MeV, using the dynamical cluster-decay model (DCM), an extension of the PCM with temperature T- and angular momentum ℓ-effects included. The β2-deformed fragments of 244Pu* in the mass range A2 = 106- 113 (plus their complementary heavy fragments), corresponding to asymmetric fission peaks, are found contributing towards the fission cross-section. Finally, the potential energy surfaces and barrier modification effects are presented for the relative comparison of spontaneous and the heavy-ion induced fission processes. Both are found to behave similar with respect to the probable emission of fragments and hence point out to the shell closure property of the decay fragments.

  9. Spontaneous fission of superheavy nuclei in a macroscopic-microscopic model

    International Nuclear Information System (INIS)

    Lojewski, Z.

    2012-01-01

    A systematic study of spontaneous fission half-lives of superheavy nuclei in the framework of the macroscopic-microscopic method was performed. The macroscopic-microscopic calculations of the half-lives consist in determining the collective potential energy V which splits into microscopic and smooth average macroscopic parts as well as into a nucleus mass tensor of the nucleus undergoing the fission process. The microscopic part of the energy is calculated using the single-particle Woods-Saxon potential with a universal set of parameters. Two models of the residual pairing interaction were studied. In the first approach we used monopole pairing (with constant matrix elements G). In the second approximation the pairing matrix elements were calculated with ?-force and are state dependent. As the macroscopic part of collective energy we examined four different macroscopic models of nuclear energy: Myers - Swiatecki liquid drop, Droplet expansion, Yukawa-plus-Exponential and the Lublin-Strasbourg Drop model. The analysis covers a wide range of even-even superheavy nuclei from Z = 100 to Z = 126. The calculations of spontaneous fission half-lives were performed by means of a WKB approximation, in the multi-dimensional dynamical-programming method within parameters describe the shape of nuclei. The studies offer an opportunity of a comprehensive approach to a very interesting group of exotic heavier nuclei, which are currently investigated by experimenters

  10. Spontaneous Fission and alpha -Decay Half-Lives of Superheavy Nuclei in Different Macroscopic Energy Models

    CERN Document Server

    Lojewski, Z; Pomorski, K

    2003-01-01

    Spontaneous fission half-lives (T sub s sub f) of the heaviest nuclei are calculated in the macroscopic-microscopic approach based on the deformed Woods-Saxon potential. Four different models of the macroscopic energy are examined and their influence on the results is discussed. The calculations of (T sub s sub f) are performed within WKB approximation. Multi-dimensional dynamical-programming method (MDP) is applied to minimize the action integral in a 3-dimensional space of deformation parameters describing the nuclear shape (beta sub 2 ,beta sub 4 ,beta sub 6).

  11. Detailed study of the angular correlations in the prompt neutron emission in spontaneous fission of 252Cf

    OpenAIRE

    KOPATCH Y.; CHIETERA A.; STUTTGE L.; GOENNENWEIN F.; MUTTERER M.; GAGARSKI A.; GUSEVA I.; CHERNYSHEVA E; DORVAUX O; HAMBSCH Franz-Josef; HANAPPE F.; MEZENTSEVAH Z.; TELEZHNIKOVCH S.

    2015-01-01

    An experiment has been performed at IPHC Strasbourg, aimed at the detailed investigation of angular correlations in the neutron emission from spontaneous fission of 252Cf. Fission fragments were measured by the angle-sensitive double ionization chamber CODIS while neutrons were detected by a set of 60 DEMON scintillator counters. The main aim of the experiment is the observation of the correlation between the fragment spins and neutron emission anisotropy. Preliminary results, based on the Mo...

  12. A spike of 4298Mo in yields of uranium spontaneous fission an extension of shell structure effect

    International Nuclear Information System (INIS)

    Masuda, Akimasa; Takahashi, Kazuya; Kawashima, Atsumichi.

    1993-01-01

    The investigations of the isotopic abundance ratios of molybdenum in zircon have shown that the molybdenum isotopic composition obtained reflects two effects: (1) spontaneous fission of 92 238 U contained in the zircon and (2) double beta decay of 40 96 Zr. Interestingly, however, the products due to the spontaneous fission appear to have a strange large excess (spike) of 42 98 Mo. It intrigues us that 92 minus 42 leaves 50, one of the outstanding magic numbers. It is suggested in the present communication that the strange spike of 42 98 Mo in question can result from a special type of spontaneous fission having essential bearings on the magic number 50 of protons and the 'magical' numbers 58 and 92 of neutrons. (author)

  13. Angular Correlations Between Fragment Spin and Prompt Neutron Evaporation in Spontaneous Fission of 252Cf: CORA-Demon Experiment

    Science.gov (United States)

    Prokhorova, E.; Gönnenwein, F.; Kopatch, Yu.; Mutterer, M.; Hanappe, F.; Kinnard, V.; Stuttgé, L.; Dorvaux, O.; Wollersheim, H.-J.

    2007-05-01

    A novel method to search for the anisotropic emission of prompt neutrons in the center-of-mass system of fission fragments is presented. The anisotropy is conjectured to be due to the large spins of fission fragments are known to carry. Triple neutron- neutron-fragment correlations in spontaneous fission of 252Cf were investigated in an exploratory experiment dubbed CORA-DEMON experiment. Fission fragments were intercepted in a double ionization chamber while neutrons were spotted in 2 two-dimensional cylindrical walls of Demon detectors with the target on the vertical cylinder axis. A new method of analysis of triple angular correlations between 2 neutrons and a fission fragment was applied. Preliminary results are reported.

  14. Pre-scission configuration of the tri-nuclear system at spontaneous ternary fission of {sup 252}Cf

    Energy Technology Data Exchange (ETDEWEB)

    Nasirov, A.K. [Joint Institute for Nuclear Research, BLTP, Dubna (Russian Federation); Institute of Nuclear Physics, Ulugbek, Tashkent (Uzbekistan); Tashkhodjaev, R.B. [Institute of Nuclear Physics, Ulugbek, Tashkent (Uzbekistan); Inha University in Tashkent, Tashkent (Uzbekistan); Oertzen, W. von [Helmholtz-Zentrum Berlin, Berlin (Germany); Freie Universitaet, Fachbereich Physik, Berlin (Germany)

    2016-05-15

    The potential energy surface for the pre-scission configurations of tri-nuclear systems formed in the spontaneous ternary fission of {sup 252}Cf is calculated. The fission channel {sup 70}Ni+{sup 50}Ca+{sup 132}Sn is chosen as one of the more probable channels of true ternary fission of {sup 252}Cf. A study of the collinear arrangement of the reaction products for true ternary fission is the aim of this work. The results are presented as a function of the relative distance R{sub 12} between the centres of mass of {sup 70}Ni and {sup 132}Sn and the distance from the centre of mass of {sup 50}Ca, which is perpendicular to R{sub 12}. The results show that only for a particular range of the R{sub 12} values the collinear tripartion of the fissioning nucleus occurs. (orig.)

  15. Neutron-neutron angular correlations in spontaneous fission of 252Cf and 240Pu

    Science.gov (United States)

    Verbeke, J. M.; Nakae, L. F.; Vogt, R.

    2018-04-01

    Background: Angular anisotropy has been observed between prompt neutrons emitted during the fission process. Such an anisotropy arises because the emitted neutrons are boosted along the direction of the parent fragment. Purpose: To measure the neutron-neutron angular correlations from the spontaneous fission of 252Cf and 240Pu oxide samples using a liquid scintillator array capable of pulse-shape discrimination. To compare these correlations to simulations combining the Monte Carlo radiation transport code MCNPX with the fission event generator FREYA. Method: Two different analysis methods were used to study the neutron-neutron correlations with varying energy thresholds. The first is based on setting a light output threshold while the second imposes a time-of-flight cutoff. The second method has the advantage of being truly detector independent. Results: The neutron-neutron correlation modeled by FREYA depends strongly on the sharing of the excitation energy between the two fragments. The measured asymmetry enabled us to adjust the FREYA parameter x in 240Pu, which controls the energy partition between the fragments and is so far inaccessible in other measurements. The 240Pu data in this analysis was the first available to quantify the energy partition for this isotope. The agreement between data and simulation is overall very good for 252Cf(sf ) and 240Pu(sf ) . Conclusions: The asymmetry in the measured neutron-neutron angular distributions can be predicted by FREYA. The shape of the correlation function depends on how the excitation energy is partitioned between the two fission fragments. Experimental data suggest that the lighter fragment is disproportionately excited.

  16. Spectroscopy of neutron-rich nuclei produced in the spontaneous fission of californium-252

    Science.gov (United States)

    Simon, Michael Wilhelm

    1999-10-01

    A new experimental technique has been developed for the spectroscopic investigation of the neutron-rich products of 252Cf(SF). The charged-particle detector CHICO was coupled to the Ge-detector array GAMMASPHERE and a thin fission source was used allowing the collection of high-statistics, high-fold γ-ray data in kinematic coincidence with the recoiling fission partners. The selectivity provided by this technique allows the γ-rays to be assigned unambiguously to the heavy or light fission partner. The added sensitivity allows many rotational bands to be extended to ~20 ħ, and a sensitivity to nuclei produced with a yield of 5 × 10-5 /fission was achieved by mass-gating the γ-ray spectra. The charged-particle detector CHICO was developed for this experiment and for studies utilizing other binary reactions, such as Coulomb excitation, transfer and fusion-fission reactions. The detector covers a total solid angle of 2.8 sr and has a time resolution of 500 ps, resulting in a mass resolution of Δm/m = 5% for beam experiments, or 8 mass units for spontaneous fission. This technique was used to set limits, in agreement with shell model predictions, on the E3 decay of the / - level in 135I. Rotational bands in 102,104,106,108Mo, 112Ru, 152,154,156 Nd, 156,158,160Sm were extended to higher spin. Band crossings were observed in the ground and γ-band in 104Mo. The γ-band of 112Ru shows continued tri-axial behavior at higher spin. The yrast rotational bands in 112,113,114,115,116 Pd were extended and rotational bands built on the low-lying isomeric levels in 113,115Pd were newly identified. The behavior of the observed band crossings in the ground and isomer bands of 113,115 Pd, when compared to the neighboring 111,113 Rh and cranked shell model calculations indicate that the predicted change from prolate to oblate shapes in the neutron-rich Pd does not occur before 116Pd. In a separate experiment, the lifetimes in 165Ho of the K=/ - ground band, up to spin / - ħ, and

  17. Progress in fission product nuclear data

    International Nuclear Information System (INIS)

    Lammer, M.

    1984-09-01

    This is the tenth issue of a report series on Fission Product Data, which informs us about all the activities in this field, which are planned, ongoing, or have recently been completed. The types of activities included are measurements, compilations and evaluations of: fission product yields (neutron induced and spontaneous fission), neutron reaction cross sections of fission products, data related to the radioactive decay of fission products, delayed neutron data of fission products, lumped fission product data (decay heat, absorption, etc.). There is also a section with recent references relative to fission product nuclear data

  18. An SSNTD study of spontaneous fission fragments from the soil-gas samples of Bakreswar thermal springs

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Debasish; Ghose, Debasis; Sastri, R.C. E-mail: res@juphys.ernet.in

    2001-04-01

    During the course of investigations on the radon and stable gas migration around the hot spring zone at Bakreswar, Birbhum in India, it was noticed that CR-39 plastic detectors used for the detection of radon revealed tracks with much bigger diameters than usual for alpha particle tracks. Exposed CR-39 detectors etched adapting sequential etching technique confirmed the presence of bigger diameter tracks similar in nature to the tracks formed by spontaneous fission fragments. This paper presents the results of these observations along with the histogram plots of the track number versus track diameter that indicate an asymmetric distribution as was seen for mass distribution of spontaneous fission fragments.

  19. Differential angular distribution of prompt gamma rays from spontaneous fission of 252Cf

    Science.gov (United States)

    Skarsvåg, K.

    1980-08-01

    The differential angular distribution of prompt γ rays from spontaneous fission of 252Cf has been measured. The source was on a thick backing, and the measurements have been performed in forward and backward geometries. An NaI(Tl) crystal was used as a γ-ray detector, and the prompt neutrons from fission were rejected by time of flight. The total number of γ rays emitted within 12 ns after fission with energies greater than 0.114 MeV is 9.7 +/- 0.4 per fission, and the total γ-ray energy released is (7.0+/-0.3) MeV per fission. Results from earlier experiments that more γ rays are emitted from the light than from the heavy fragment group, are substantiated. The anisotropy A=I(0°)I(90°)-1 is small and even negative at low energies, reaches a maximum of about 25% at energies of about 0.50-0.65 MeV, and gets gradually smaller at higher energies. No significant difference in the anisotropy as measured with a nonmagnetic (Pt) and a magnetic (Ni) backing has been found. With the assumption that the angular momentum is aligned in a plane perpendicular to the direction of fission, the results can be consistently described within the statistical model in terms of pure dipole and quadrupole radiation with allowance for stretched E2 cascades from even-even fragments. It is concluded that the root mean square value of the primary angular momentum of the fragments is Jrms=(6.5+/-1.0)ℏ, the average angular momentum is decreasing 1.0ℏ per γ ray emitted, and the value of the spin cutoff parameter during γ-ray deexcitation of the fragments is σ=2.4+0.8-0.5. The dipole and the quadrupole components are about equally strong at high γ-ray energies, the dipole component predominates at low energies, and the quadrupole component at intermediate energies. Statistical dipole and quadrupole transitions (stretched for the last ones) account for 38% and 50% of the γ rays, respectively, and stretched E2 transitions in cascades from even-even fragments account for the remaining

  20. Detailed Study of the Angular Correlations in the Prompt Neutron Emission in Spontaneous Fission of 252Cf

    Science.gov (United States)

    Kopatch, Yu.; Chietera, A.; Stuttgé, L.; Gönnenwein, F.; Mutterer, M.; Gagarski, A.; Guseva, I.; Chernysheva, E.; Dorvaux, O.; Hambsch, F.-J.; Hanappe, F.; Mezentseva, Z.; Telezhnikov, S.

    An experiment has been performed at IPHC Strasbourg, aimed at the detailed investigation of angular correlations in the neutron emission from spontaneous fission of 252Cf. Fission fragments were measured by the angle-sensitive double ionization chamber CODIS while neutrons were detected by a set of 60 DEMON scintillator counters. The main aim of the experiment is the observation of the correlation between the fragment spins and neutron emission anisotropy. Preliminary results, based on the Monte-Carlo simulations, as well as the preliminary analysis of the experimental data are shown.

  1. Improved Fission Neutron Data Base for Active Interrogation of Actinides

    Energy Technology Data Exchange (ETDEWEB)

    Pozzi, Sara; Czirr, J. Bart; Haight, Robert; Kovash, Michael; Tsvetkov, Pavel

    2013-11-06

    This project will develop an innovative neutron detection system for active interrogation measurements. Many active interrogation methods to detect fissionable material are based on the detection of neutrons from fission induced by fast neutrons or high-energy gamma rays. The energy spectrum of the fission neutrons provides data to identify the fissionable isotopes and materials such as shielding between the fissionable material and the detector. The proposed path for the project is as follows. First, the team will develop new neutron detection systems and algorithms by Monte Carlo simulations and bench-top experiments. Next, They will characterize and calibrate detection systems both with monoenergetic and white neutron sources. Finally, high-fidelity measurements of neutron emission from fissions induced by fast neutrons will be performed. Several existing fission chambers containing U-235, Pu-239, U-238, or Th-232 will be used to measure the neutron-induced fission neutron emission spectra. The challenge for making confident measurements is the detection of neutrons in the energy ranges of 0.01 – 1 MeV and above 8 MeV, regions where the basic data on the neutron energy spectrum emitted from fission is least well known. In addition, improvements in the specificity of neutron detectors are required throughout the complete energy range: they must be able to clearly distinguish neutrons from other radiations, in particular gamma rays and cosmic rays. The team believes that all of these challenges can be addressed successfully with emerging technologies under development by this collaboration. In particular, the collaboration will address the area of fission neutron emission spectra for isotopes of interest in the advanced fuel cycle initiative (AFCI).

  2. Study of ternary and quaternary spontaneous fission of sup 2 sup 5 sup 2 Cf with the NESSI detector

    CERN Document Server

    Tishchenko, V G; Hilscher, D; Jahnke, U

    2002-01-01

    Ternary and quaternary spontaneous decay of sup 2 sup 5 sup 2 Cf was studied with the NESSI detector, a combination of two 4 pi detectors for charged particles, neutrons and gamma-rays. The applied method of particle identification by measuring the energies and relative time-of-flights of the decay products is shown to be very effective for the study of rare decay modes. The energy and angular distributions of the decay products, the associated neutron multiplicities, the total energy of the prompt gamma-radiation as well as correlations between the various observables were measured for the first time in a single full-scale experiment. The characteristics of ternary fission known from previous investigations are confirmed in the frame of a methodically independent experiment. Preliminary estimates of the quaternary fission yield are presented. An attempt is made to determine the mechanism of quaternary fission.

  3. Spontaneous fission Vs alpha decay of superheavy nuclei with reduced uncertainty of Qα

    International Nuclear Information System (INIS)

    Santhosh Kumar, S.; Victor Babu, A.; Preetha, P.

    2015-01-01

    In recent experiments, α-decay has been indispensable for the identification of new nuclides. Because the experimentalists have to evaluate the values of the α-decay half-lives, during the experimental design, it is quite important and necessary to investigate the α decay of SHN theoretically. Besides the role of shell effects in the stability of SHN, the α-decay or spontaneous fission(SF) took important role. SHN with atomic number beyond 110 predominantly undergo sequential α-decay and long α-decay chains usually terminate by the SF. In experiment the measurement is mainly α- decay Q values and half-lives, while the major goal of the theory is to predict the half-lives to serve the experimental design. Q-value, one of the crucial quantity for a quantitative prediction of decay half-life, affects strongly the calculation of the half-life due to the exponential law, i.e., α- decay rates exhibit an exponential dependence (Geigger-Nuttall) on emission energy. Therefore it is extremely important and necessary to obtain an accurate theoretical Q-value in a reliable half life prediction during the experimental design

  4. Formation and distribution of fragments in the spontaneous fission of 240Pu

    Science.gov (United States)

    Sadhukhan, Jhilam; Zhang, Chunli; Nazarewicz, Witold; Schunck, Nicolas

    2017-12-01

    Background: Fission is a fundamental decay mode of heavy atomic nuclei. The prevalent theoretical approach is based on mean-field theory and its extensions where fission is modeled as a large amplitude motion of a nucleus in a multidimensional collective space. One of the important observables characterizing fission is the charge and mass distribution of fission fragments. Purpose: The goal of this Rapid Communication is to better understand the structure of fission fragment distributions by investigating the competition between the static structure of the collective manifold and the stochastic dynamics. In particular, we study the characteristics of the tails of yield distributions, which correspond to very asymmetric fission into a very heavy and a very light fragment. Methods: We use the stochastic Langevin framework to simulate the nuclear evolution after the system tunnels through the multidimensional potential barrier. For a representative sample of different initial configurations along the outer turning-point line, we define effective fission paths by computing a large number of Langevin trajectories. We extract the relative contribution of each such path to the fragment distribution. We then use nucleon localization functions along effective fission pathways to analyze the characteristics of prefragments at prescission configurations. Results: We find that non-Newtonian Langevin trajectories, strongly impacted by the random force, produce the tails of the fission fragment distribution of 240Pu. The prefragments deduced from nucleon localizations are formed early and change little as the nucleus evolves towards scission. On the other hand, the system contains many nucleons that are not localized in the prefragments even near the scission point. Such nucleons are distributed rapidly at scission to form the final fragments. Fission prefragments extracted from direct integration of the density and from the localization functions typically differ by more than

  5. The statistical model calculation of prompt neutron spectra from spontaneous fission of {sup 244}Cm and {sup 246}Cm

    Energy Technology Data Exchange (ETDEWEB)

    Gerasimenko, B.F. [V.G. Khlopin Radium Inst., Saint Peterburg (Russian Federation)

    1997-03-01

    The calculations of integral spectra of prompt neutrons of spontaneous fission of {sup 244}Cm and {sup 246}Cm were carried out. The calculations were done by the Statistical Computer Code Complex SCOFIN applying the Hauser-Feschbach method as applied to the description of the de-excitation of excited fission fragments by means of neutron emission. The emission of dipole gamma-quanta from these fragments was considered as a competing process. The average excitation energy of a fragment was calculated by two-spheroidal model of tangent fragments. The density of levels in an excited fragment was calculated by the Fermi-gas model. The quite satisfactory agreement was reached between theoretical and experimental results obtained in frames of Project measurements. The calculated values of average multiplicities of neutron number were 2,746 for {sup 244}Cm and 2,927 for {sup 246}Cm that was in a good accordance with published experimental figures. (author)

  6. SOURCES 4A: A Code for Calculating (alpha,n), Spontaneous Fission, and Delayed Neutron Sources and Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Madland, D.G.; Arthur, E.D.; Estes, G.P.; Stewart, J.E.; Bozoian, M.; Perry, R.T.; Parish, T.A.; Brown, T.H.; England, T.R.; Wilson, W.B.; Charlton, W.S.

    1999-09-01

    SOURCES 4A is a computer code that determines neutron production rates and spectra from ({alpha},n) reactions, spontaneous fission, and delayed neutron emission due to the decay of radionuclides. The code is capable of calculating ({alpha},n) source rates and spectra in four types of problems: homogeneous media (i.e., a mixture of {alpha}-emitting source material and low-Z target material), two-region interface problems (i.e., a slab of {alpha}-emitting source material in contact with a slab of low-Z target material), three-region interface problems (i.e., a thin slab of low-Z target material sandwiched between {alpha}-emitting source material and low-Z target material), and ({alpha},n) reactions induced by a monoenergetic beam of {alpha}-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 43 actinides. The ({alpha},n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 89 nuclide decay {alpha}-particle spectra, 24 sets of measured and/or evaluated ({alpha},n) cross sections and product nuclide level branching fractions, and functional {alpha}-particle stopping cross sections for Z < 106. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code outputs the magnitude and spectra of the resultant neutron source. It also provides an analysis of the contributions to that source by each nuclide in the problem.

  7. SOURCES 4C : a code for calculating ([alpha],n), spontaneous fission, and delayed neutron sources and spectra.

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, W. B. (William B.); Perry, R. T. (Robert T.); Shores, E. F. (Erik F.); Charlton, W. S. (William S.); Parish, Theodore A.; Estes, G. P. (Guy P.); Brown, T. H. (Thomas H.); Arthur, Edward D. (Edward Dana),; Bozoian, Michael; England, T. R.; Madland, D. G.; Stewart, J. E. (James E.)

    2002-01-01

    SOURCES 4C is a computer code that determines neutron production rates and spectra from ({alpha},n) reactions, spontaneous fission, and delayed neutron emission due to radionuclide decay. The code is capable of calculating ({alpha},n) source rates and spectra in four types of problems: homogeneous media (i.e., an intimate mixture of a-emitting source material and low-Z target material), two-region interface problems (i.e., a slab of {alpha}-emitting source material in contact with a slab of low-Z target material), three-region interface problems (i.e., a thin slab of low-Z target material sandwiched between {alpha}-emitting source material and low-Z target material), and ({alpha},n) reactions induced by a monoenergetic beam of {alpha}-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 44 actinides. The ({alpha},n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 107 nuclide decay {alpha}-particle spectra, 24 sets of measured and/or evaluated ({alpha},n) cross sections and product nuclide level branching fractions, and functional {alpha}-particle stopping cross sections for Z < 106. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code provides the magnitude and spectra, if desired, of the resultant neutron source in addition to an analysis of the'contributions by each nuclide in the problem. LASTCALL, a graphical user interface, is included in the code package.

  8. Systematic study on the competition between α-decay and spontaneous fission of superheavy nuclei

    Science.gov (United States)

    Zhang, Y. L.; Wang, Y. Z.

    2017-10-01

    The competition between α-decay and spontaneous fission (SF) of Z = 112 isotopes are studied. The α-decay half-lives are estimated by the generalized liquid-drop model (GLDM) and several sets of analytic formulas. These formulas include the Royer formula, Viola-Seaborg semiempirical (VSS) formula and universal decay law (UDL). For the SF, its half-lives are calculated by using the Xu, Ren, Karpov and Santhosh formulas. It is shown that the predicted α-decay half-lives by different approaches are more or less identical. However, the SF half-lives are highly sensitive to models. To test the accuracies of different SF formulas, the half-lives of 56 even-even heavy nuclei are calculated by these formulas. By comparing with the experimental data, it is found that the Xu formula is the most accurate one to reproduce the experimental SF half-lives. This allows us to make a systematic prediction on the competition between α-decay and SF of even-even superheavy nuclei (SHN) with Z = 104- 120 by using the Xu formula and the above mentioned models on α-decay. The calculations suggest that 258,260104, 268-276110, 270-280112, 272-286114, 274-294116, 284-302118 and 292-308120 have smaller α-decay half-lives than those of SF. Thus these nuclei can be synthesized and identified via α-decay in the laboratory. In addition, it is observed that N = 162, 178, 184 and 196 may be the submagic or magic numbers. Finally, an extensive study on the possible α-decay chains for Z = 120 isotopes is performed. It is predicted that six sequential α-decay chains can be observed from 292-296120, four α-decay chains from 298120, three α-decay chains from 300,302120, two α-decay chains from 304,306120, and only one α-decay chain from 308120. These nuclei are the most likely candidates to be synthesized experimentally via α-decay in the near future.

  9. Study of scission shapes in spontaneous ternary fission of 252Cf

    International Nuclear Information System (INIS)

    Singer, P.; Schwalm, D.; Thirolf, P.; Goennenwein, F.; Hesse, M.

    1995-06-01

    A new kinematic study on the ternary fission of 252 Cf has been conducted by registering prompt neutrons and fission γ rays coincidence with light charged particles (LCP) and fission fragments. The aim is to investigate changes in fragment deformation energy between the binary and ternary fission modes from measured prompt neutron angular distributions and multiplicities, and to explore the influence of light particle emission on the energy distribution, multiplicity and angular anisotropy of γ rays emitted during fragment de-excitation. The experiment was performed at the MPI Heidelberg using the Darmstadt-Heidelberg crystal ball spectrometer as γ-ray and neutron detector. Fragments were identified by a double-E measurement with an angular sensitive twin ionization chamber (IC). Light charged particles from fission were measured by ΔE-E telescopes composed of ΔE ICs and silicon PIN diodes. The telescopes enable to identify various LCPs which are emitted much more rarely than ternary α particles. The parameters of the experiment and the method of data analysis are described and first results presented. (orig.)

  10. He and Be ternary spontaneous fission of sup 2 sup 5 sup 2 Cf

    CERN Document Server

    Hwang, J K; Ramayya, A V; Hamilton, J H

    2002-01-01

    Ternary and binary fission studies of sup 2 sup 5 sup 2 Cf have been carried out by using the Gammasphere detector array with light charged particle (LCD) detectors. The relative sup 4 He and sup 5 He ternary fission yields were determined. The kinetic energies of the sup 5 He and sup 4 He ternary particles were found to be approximately 11 and 16 MeV, respectively. The sup 5 He particles contribute 10-20 % to the total observed alpha ternary yield. The data indicate that in nuclei with octupole deformations the population for the negative parity bands might be enhanced in the alpha ternary fission. >From LCP-gamma double gated spectra, neutron multiplicity distributions for alpha ternary fission pairs were measured. The average neutron multiplicity decreases about 0.7 AMU in going from the binary to alpha ternary fission in the approximately same mass splittings (104-146). From the analysis of the gamma-gamma matrix gated on the sup 1 sup 0 Be particles, the two fragment pairs of sup 1 sup 3 sup 8 Xe - sup 1...

  11. Study of the stability of the ground states and K-isomeric states of 250Fm and 254102 against spontaneous fission

    International Nuclear Information System (INIS)

    Lazarev, Yu.A.; Lobanov, Yu.V.; Sagajdak, R.N.; Utenkov, V.K.; Kharitonov, Yu.P.; Shirokovskij, I.V.; Tret'yakova, S.P.; Oganessyan, Yu.Ts.

    1988-01-01

    By employing the 249 Cf( 4 He, 3n) and 208 Pb( 48 Ca,2n) reactions, experiments to study the stability against spontaneous fission of the nuclides 250 Fm and 254 102 as well as of the two-quasi-particle (2 q-p) K isomers 250 Fm (T 1/2 =1,8±0,1 s) and 254 102 (T 1/2 =0,28±0,04 s) have been performed. The groundstate spontaneous fission of the two nuclides has been discovered and the corresponding branching ratios b sf and partial half-lives T sf , respectively, have been determined to be: (6,9±1,0)x10 -5 , 0,83±0,15 yr for 250 Fm; (1,7±0,5)x10 -3 , (3,2±0,9)x10 4 s for 254 102. As a by-product of these studies, new data about cross sections of the 206,208 Pb( 48 Ca,xn) reactions have been obtained. Experiments designed to search for the spontaneous fission of the 2 q-p K-isometric states in 250 Fm and 254 102 have not revealed the effect in question. The lower limits of the ratios of the partial spontaneous fission half-lives for the 2 q-p K-isomeric states to those for the respective ground states, T * sf /T sf , have been established to be≥10 -1 for 250m Fm/ 250 Fm and ≥5x10 -3 for 254m 102/ 254 102. This means that the stability of the 2 q-p K-isomeric states in 250 Fm and 254 102 against spontaneous fission is practically not inferior to that of the ground states of these nuclei. In accord with the experimental findings, the theoretical estimates of T * sf /T sf made in the present paper show that, due to the influence of the specialization and blocking effects on the potential energy and the effective mass associated with fission, spontaneous fission from 2 q-p K-isomeric states cannot be facilitated but, on the contrary, should be essentially hindered compared with ground-state spontaneous fission

  12. SSNTD study of the probable influence of alpha activity on the mass distribution of sup 2 sup 5 sup 2 Cf fission fragments

    CERN Document Server

    Paul, D; Sastri, R C; Ghose, D

    1999-01-01

    The SSNTD has come a long way in its application for the study of nuclear phenomena. Spontaneous fission of transuranic elements is one such phenomena wherein use of SSNTD offers easy registration of the signature of the fission fragments. The object of the present study is to explore whether any one of the track parameters such as the diameter can be used to estimate the atomic mass ratios of the spontaneous fission fragments. The spontaneous fission data from sup 2 sup 5 sup 2 Cf recorded almost at the end of one and four half-life periods for alpha decay are analysed, taking a plot of the number of tracks versus the track diameter. From these plots it is seen that initially, when significant alpha activity of sup 2 sup 5 sup 2 Cf persists, the fission fragments appear to cluster into two predominant groups as indicated by two peaks. The ratio of the diameters at these peak positions appear to be related to the ratio of average mass numbers of the light and heavy groups of fission fragments. However, absenc...

  13. Identification of new neutron-rich rare-earth nuclei produced in /sup 252/Cf spontaneous fission

    CERN Document Server

    Greenwood, R C; Gehrke, R J; Meikrantz, D H

    1981-01-01

    A program of systematic study of the decay properties of neutron-rich rare-earth nuclei with 30 sspontaneous fission, is currently underway using the Idaho ESOL (Elemental Separation On Line) Facility. The chemistry system used for the rare-earth elemental separations consists of two high-performance chromatography columns connected in series and coupled to the /sup 252 /Cf fission source via a helium gas-jet transport arrangement. The time delay for separation and initiation of gamma -ray counting with results which have been obtained to date with this system include the identification of a number of new neutron-rich rare-earth isotopes including /sup 155/Pm (t/sub 1/2/=48+or-4 s) and /sup 163/Gd (t/sub 1 /2/=68+or-3 s), in addition to 5.51 min /sup 158/Sm which was identified in an earlier series of experiments. (11 refs).

  14. Study of the shielding for spontaneous fission sources of Californium-252; Estudio de blindaje para fuentes de fision espontanea de Californio-252

    Energy Technology Data Exchange (ETDEWEB)

    Davila R, I

    1991-06-15

    A shielding study is made to attenuate, until maximum permissible levels, the neutrons radiation and photons emitted by spontaneous fission coming from a source of Californium-252. The compound package by a database (Library DLC-23) and the ANISNW code is used, in it version for personal computer. (Author)

  15. Resolution of complex gamma spectra from triple-coincidence data Ba-Mo split in sup 2 sup 5 sup 2 Cf spontaneous fission

    CERN Document Server

    Wu, S C; Rasmussen, J O; Daniel, A V; Hwang, J K; Ramayya, A V; Hamilton, J H

    2002-01-01

    Using triple-coincidence events of prompt fission gamma rays from spontaneous fission of sup 2 sup 5 sup 2 Cf, we made a new analysis of the yield matrix of coincident pairs of barium (Z=56) and molybdenum (Z=42) fission fragments. Branching from gamma-bands (K=2) and octupole-bands (K=0) were also measured. From this reanalysis the previously proposed 'extra-hot-fission mode' (8-10 neutrons evaporated) is much weaker than first reported. In this paper, we discuss in detail the methodology, including background subtraction for triple-coincidence data. The importance of minimal compression spectra allowing least-squares peak-fitting analysis is emphasized.

  16. Fragment angular momenta and descent dynamics in sup 2 sup 5 sup 2 Cf spontaneous fission

    CERN Document Server

    Popeko, J S; Ter-Akopian, G M

    2002-01-01

    Average angular momentum values of primary fission fragments as a function of neutron multiplicity and neutron-to-proton ratio were extracted for the first time for the Mo-Ba and Zr-Ce charge splittings of sup 2 sup 5 sup 2 Cf. The results are discussed in terms of the energy balance occurring at the scission point. For the first time we show that for large fragment elongation associated with larger numbers of evaporated neutrons (v sub t sub o sub t >=6), essentially only zero point bending oscillation takes places, i.e. T = 0 for this degree of freedom. For the major part of the fission events, with v sub t sub o sub t = 2-5, the banding oscillation is excited to a temperature of 2-3 MeV. Such a high bending temperature implies that the coupling between the collective and internal degrees of freedom is weak at the descent of the even-even nucleus of sup 2 sup 5 sup 2 Cf to the scission point. The dipole oscillations occurring at the descent take away some 2.5 - 3.0 MeV from the release energy. A correlation...

  17. Spontaneous Plasticity of Multineuronal Activity Patterns in Activated Hippocampal Networks

    Directory of Open Access Journals (Sweden)

    Atsushi Usami

    2008-01-01

    Full Text Available Using functional multineuron imaging with single-cell resolution, we examined how hippocampal networks by themselves change the spatiotemporal patterns of spontaneous activity during the course of emitting spontaneous activity. When extracellular ionic concentrations were changed to those that mimicked in vivo conditions, spontaneous activity was increased in active cell number and activity frequency. When ionic compositions were restored to the control conditions, the activity level returned to baseline, but the weighted spatial dispersion of active cells, as assessed by entropy-based metrics, did not. Thus, the networks can modify themselves by altering the internal structure of their correlated activity, even though they as a whole maintained the same level of activity in space and time.

  18. Covariances for measured activation and fission ratios data

    International Nuclear Information System (INIS)

    Smith, D.L.; Meadows, J.W.; Watanabe, Y.

    1986-01-01

    Methods which are routinely used in the determination of covariance matrices for both integral and differential activation and fission-ratios data acquired at the Argonne National Laboratory Fast-Neutron Generator Facility (FNG) are discussed. Special consideration is given to problems associated with the estimation of correlations between various identified sources of experimental error. Approximation methods which are commonly used to reduce the labor involved in this analysis to manageable levels are described. Results from some experiments which have been recently carried out in this laboratory are presented to illustrate these procedures. 13 refs., 1 fig., 5 tabs

  19. Spontaneous activity in peripheral diaphragmatic lymphatic loops.

    Science.gov (United States)

    Moriondo, Andrea; Solari, Eleonora; Marcozzi, Cristiana; Negrini, Daniela

    2013-10-01

    The spontaneous contractility of FITC-dextran-filled lymphatics at the periphery of the pleural diaphragm was documented for the first time "in vivo" in anesthetized Wistar rats. We found that lymphatic segments could be divided into four phenotypes: 1) active, displaying rhythmic spontaneous contractions (51.8% of 197 analyzed sites); 2) stretch-activated, whose contraction was triggered by passive distension of the vessel lumen (4.1%); 3) passive, which displayed a completely passive distension (4.5%); and 4) inert, whose diameter never changed over time (39.6%). Smooth muscle actin was detected by immunofluorescence and confocal microscopy in the vessel walls of active but also of inert sites, albeit with a very different structure within the vessel wall. Indeed, while in active segments, actin was arranged in a dense mesh completely surrounding the lumen, in inert segments actin decorated the vessels wall in sparse longitudinal strips. When located nearby along the same lymphatic loop, active, stretch-activated, and passive sites were always recruited in temporal sequence starting from the active contraction. The time delay was ∼0.35 s between active and stretch-activated and 0.54 s between stretch-activated and passive segments, promoting a uniform lymph flux of ∼150/200 pl/min. We conclude that, unlike more central diaphragmatic lymphatic vessels, loops located at the extreme diaphragmatic periphery do require an intrinsic pumping mechanism to propel lymph centripetally, and that such an active lymph propulsion is attained by means of a complex interplay among sites whose properties differ but are indeed able to organize lymph flux in an ordered fashion.

  20. Prompt Gamma-Ray Spectroscopy Studies in Neutron - Molybdenum, Ruthenium and Barium Isotopes from Californium -252 Spontaneous Fission.

    Science.gov (United States)

    Lu, Qi Hong

    1995-01-01

    Studies of the prompt gamma -rays emitted in the spontaneous fission of ^ {252}Cf with large gamma -ray detector arrays at Oak Ridge National Laboratory and Lawrence Berkeley National Laboratory were carried out. New levels were identified in ^ {108-112}Ru. Evidence for identical bands is observed in the ground bands of ^{108,110 }Ru--the lightest extended identical bands in neighboring even-even nuclei has been observed. The first observation of similar energy transitions out of gamma-vibrational levels from 3 ^{+} to 7^{+ } in those two isotopes is reported. Levels to 16^{+} in the ground band and to 9^{+} in the gamma-vibrational band in ^{112}Ru are presented. Calculations in a generalized collective model including rotation-vibration interaction can reproduce the level energies in the ground and gamma bands and the branching ratios out of the 4^{+} and 5^{+}252 }Cf SF is presented. Zero up to ten neutron emission channels are reported. This is the first report of 10 neutron emission. The 0, 7-9, and new 10 emission yields for Mo-Ba pairs are significantly larger than these yields reported previously for total ^{252 }Cf SF.

  1. Ternary fission

    International Nuclear Information System (INIS)

    Wagemans, C.

    1991-01-01

    Since its discovery in 1946, light (charged) particle accompanied fission (ternary fission) has been extensively studied, for spontaneous as well as for induced fission reactions. The reason for this interest was twofold: the ternary particles being emitted in space and time close to the scission point were expected to supply information on the scission point configuration and the ternary fission process was an important source of helium, tritium, and hydrogen production in nuclear reactors, for which data were requested by the nuclear industry. Significant experimental progress has been realized with the advent of high-resolution detectors, powerful multiparameter data acquisition systems, and intense neutron and photon beams. As far as theory is concerned, the trajectory calculations (in which scission point parameters are deduced from the experimental observations) have been very much improved. An attempt was made to explain ternary particle emission in terms of a Plateau-Rayleigh hydrodynamical instability of a relatively long cylindrical neck or cylindrical nucleus. New results have also been obtained on the so-called open-quotes trueclose quotes ternary fission (fission in three about-equal fragments). The spontaneous emission of charged particles has also clearly been demonstrated in recent years. This chapter discusses the main characteristics of ternary fission, theoretical models, light particle emission probabilities, the dependence of the emission probabilities on experimental variables, light particle energy distributions, light particle angular distributions, correlations between light particle accompanied fission observables, open-quotes trueclose quotes ternary fission, and spontaneous emission of heavy ions. 143 refs., 18 figs., 8 tabs

  2. Applications of bioassay for fission and activation products - Sept. 1980

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    This guide identifies the bases that will be used by the NRC staff in evaluating the need for license provisions to require bioassay programs in installations where employees may be subject to internal radiation exposure from the inhalation or ingestion of fission or neutron activation products. It also describes methods acceptable to the NRC staff for determining the persons to be included in a bioassay program, the sampling and measurement techniques to be used, the frequency of bioassay measurements to be made, actions to be taken based on designated levels of internal radioactivity, estimations of internal dose to be calculated from bioassay measurements, and record systems to be maintained appropriate to such bioassay programs

  3. Spontaneous Activity Drives Local Synaptic Plasticity In Vivo

    NARCIS (Netherlands)

    Winnubst, Johan; Cheyne, Juliette E; Niculescu, Dragos; Lohmann, C.

    2015-01-01

    Spontaneous activity fine-tunes neuronal connections in the developing brain. To explore the underlying synaptic plasticity mechanisms, we monitored naturally occurring changes in spontaneous activity at individual synapses with whole-cell patch-clamp recordings and simultaneous calcium imaging in

  4. Development of a gas-jet coupled ISOL facility with a /sup 252/Cf spontaneous fission source

    CERN Document Server

    Greenwood, R C; Novick, V J

    1981-01-01

    A mass separator at the INEL has been successfully coupled on-line to a source of /sup 252/Cf fission products via a He-gas jet transport arrangement using solid aerosols of NaCl as activity carriers. Initial tests of the ISOL system on-line to an approximately 7 mu g /sup 252 /Cf source are conducted using gamma-ray spectroscopic measurements of the separated /sup 138,139/Cs, /sup 141,142/Ba and /sup 142/La activities. The measured transport efficiencies through the system of approximately 3% and approximately 0.3% for the Cs and Ba isotopes, respectively, are comparable with the results of earlier tests conducted at INEL with a hollow-cathode ion source alone coupled to the He-gas jet transport arrangement. Following these tests, a general survey of the mass-separated activities is conducted with the ISOL system on-line to an approximately 600 mu g source of /sup 252/Cf. Gross beta - gamma activity is measured for samples collected at 73 mass positions. Gamma-ray spectra are measured with a Ge(Li) detector ...

  5. Using neutron angular anisotropy information to dynamically determine the ratio of the (α,n) rate to spontaneous fission rate for coincidence counting applications

    Science.gov (United States)

    Holewa, L.; Charlton, W.; Miller, E.; Pozzi, S.

    2013-02-01

    Typically, when neutron coincidence or multiplicity counting is performed, there are three unknowns: the sample mass, the leakage self-multiplication, and the ratio of the (α,n) rate of the source to the spontaneous fission rate. For a given counting time, the strength of the source or the detector efficiency must be sufficiently high for the singles, doubles, and triples count rates to represent statistically meaningful quantities. Often, the strength of the source and the allotted counting time are such that only the singles and doubles count rates are statistically meaningful. In this latter case, the ratio of (α,n) to the spontaneous fission must be estimated through some other means. With a simulated (α,n) rate, the two equations related to the singles and doubles count rates can be used to determine the sample mass. In order to determine the ratio of (α,n) to spontaneous fission rate of the source, the isotopic composition of the sample as well as the light element impurities inside the source must be known. Ideally, there would be a way to dynamically determine the (α,n) rate of the source from count rate information. In this paper, it is shown that the (α,n) rate of the source can be determined by using information about the ratio of the number of coincident neutrons at 180° to the number at 90°. By using this information, the three aforementioned unknowns can be dynamically determined through the sole use of singles and doubles count rates.

  6. Prompt Gamma-Ray Spectroscopy of Neutron-Rich Nuclides Produced in the Spontaneous Fission Process of CALIFORNIUM-252

    Science.gov (United States)

    Butler-Moore, S. Kyle

    Nuclear spectroscopy was performed on neutron -rich nuclides produced by the spontaneous fission process of ^{252}Cf. The data were taken with the Compton-suppressed Ge-detector spectrometer at the Holifield Heavy Ion Research Facility. The prompt gamma-ray transitions were isolated by using gamma-gamma and gamma-gamma -gamma coincidence techniques. Nine new states were observed in ^ {110}Ru, four of which constitute a gamma band structure up to J^pi = 7^+, and an additional J ^pi = 12^+ state which was assigned to the yrast band. The level scheme of ^{110}Ru is compared to ^{104}Ru and ^{192}Os, the latter of which shares with ^{110}Ru the distinction of having the lowest gamma-bandhead. Calculations with both the gamma-rigid triaxial nuclear model and the IBA O(6) Hamiltonian gave acceptable fits for the yrast band, but predicted a doublet clustering of states for the gamma-band, which was not observed experimentally. Studies of nuclei around doubly magic ^{132}Sn revealed for the first time energy levels of ^{136}Te and new high spin states in ^{134} Te, ^{138,140}Xe, and ^{140}Ba. The states in the yrast band of the N = 84 isotones ^ {136}Te, ^{138} Xe, and ^{140}Ba were determined up to 12^+, 12 ^+ and 8^+, respectively. The discovery of the 6^+ states provided an almost complete energy level systematics for the N = 84 isotones in the pseudo-spin f_{7/2 } shell. The energy levels of the isotopes ^{136}Te and ^{138}Xe were shown to exhibit remarkable similarities to the isotopes ^ {204}Po and ^{206 }Rn. This approximate symmetry was ascribed to the underlying shell model structure. Based upon the shell model calculations for ^{204 }Po, the 8^+, 10 ^+, and 12^+ states of ^{136}Te were hypothesized to involve core excitations of ^{134 }Sn. The higher spin states of the neutron-rich Pd isotopes ^{110,112,114}Pd were identified. Their moments of inertia exhibit backbending above spin 6^+. Cranked shell model calculations indicated that the backbendings observed at

  7. Confidence building in and through fission and fusion activities

    International Nuclear Information System (INIS)

    Toyojiro Fuketa

    1989-01-01

    The peaceful uses of atomic energy are most suitable for achieving worldwide confidence building for the following reasons. (1) In spite of the need for peaceful uses of nuclear energy, the world is facing difficulties in the public perception and acceptance of nuclear works and facilities. (2) The above difficulties are due to many factors, such as the two sides of nuclear energy peaceful and military, the possibility of a large-scale reactor accident, the lack of understanding about radiation and radioactivity, and finally, emotion and egoism. Some of these factors are unique to nuclear-energy, but in other cases of public reactions, there are many facets similar to the above factors. (3) The public concern about safety is at its highest, broadest and severest point ever, coincident with the highest life expectancy in history. Over-precaution and over-protection about certain things may sometimes spoil one's health. Nuclear energy is most definitely suffering from such a trend. As a result, a severe nuclear accident in any country results in severe damage worldwide no manner in what form the real physical effects reach other countries. (4) The huge science and technology efforts required for fission and fusion activities cannot be fully achieved by one country. Explanations of some of the above factors are given. 2 refs

  8. High spin studies of neutron-rich nuclei produced in the spontaneous fission process of californium-252

    Science.gov (United States)

    Zhang, Xueqian

    2001-08-01

    From an experiment with GAMMMASPHERE and a 252Cf spontaneous fission source, high spin studies of several neutron-rich nuclei have been carried out. In the mass region A ~ 150, a new negative-parity band in 154Nd and new negative-parity levels in 152Nd were identified and the yrast bands were extended to 18+ in 154Nd and 20+ 152Nd in a triple gamma coincidence study. These new negative-parity bands are consistent with octupole vibrational mode rather than the stable octupole deformation seen in Ba and Ce nuclei. There is a constant difference as a function of spin between the J1 values for the negative-parity band in 152Nd and J1 for the similar negative-parity band in 154Nd, however, their J2 values are essentially identical above the 4 + state. These bands indicate a new kind of identical bands associated with an octupole vibrational mode. In mass region A ~ 110, we have observed new bands in 113,115,117,118 Pd up to moderately high spin. The newly identified negative-parity yrast band energy level systematics built on the / isomeric states fit smoothly with the known systematic for other Pd isotopes, and show a minimum excitation energy at N = 68 related to a mid-shell closure. These new negative- parity yrast bands indicate a first band crossing at ¢ω ~ 0.45 MeV, nearly identical to those seen in 109,111Pd, but significantly higher than those in the positive yrast parity bands in 113,115Pd and in the even-even Pd isotopes. We have interpreted the new negative-parity yrast bands as having band crossings from the alignment of a nh/ pair, and this suggests that 113,115,117Pd maintain a prolate shape. Additionally, we have observed two new bands in 113,115 Pd, which are tentatively assigned positive parity with band crossings about 0.25 and 0.32 MeV. These lower frequencies are consistent with a nh/ pair alignment. In the neutron-rich 118Pd, the first band crossing at a frequency of ¢ω ~ 0.29 MeV was observed in its yrast band. This band crossing frequency is

  9. Progress in fission product nuclear data. No. 14

    International Nuclear Information System (INIS)

    Lammer, M.

    1994-06-01

    This is the 14th issue of a report series on Fission Product Nuclear Data published by the Nuclear Data Section of the IAEA. The types of activities included are measurements, compilations and evaluations of fission product yields, neutron reaction cross sections of fission products, data related to the radioactive decay of fission products, delayed neutron data from neutron induced and spontaneous fission, lumped fission product data. The first part of the report consists of unaltered original contributions which the authors have sent to IAEA/NDS. The second part contains some recent references relative to fission product nuclear data, which were not covered by the contributions submitted, and selected papers from conferences. The third part contains requirements for further measurements

  10. Progress in fission product nuclear data. No. 13

    International Nuclear Information System (INIS)

    Lammer, M.

    1990-11-01

    This is the 13th issue of a report series published by the Nuclear Data Section of the IAEA. The types of activities included are measurements, compilations and evaluations of: Fission product yields (neutron induced and spontaneous fission), neutron reaction cross-sections of fission products, data related to the radioactive decay of fission products, delayed neutron data of fission products and bumped fission product data (decay heat, absorption, etc.). The first part of the report consists of unaltered original data which the authors have sent to IAEA/NDS. The second part contains some recent references relative to fission product nuclear data, which were not covered by the contributions submitted, and selected papers from conferences. Part 3 contains requirements for further measurements

  11. Learning sculpts the spontaneous activity of the resting human brain

    OpenAIRE

    Lewis, Christopher M.; Baldassarre, Antonello; Committeri, Giorgia; Romani, Gian Luca; Corbetta, Maurizio

    2009-01-01

    The brain is not a passive sensory-motor analyzer driven by environmental stimuli, but actively maintains ongoing representations that may be involved in the coding of expected sensory stimuli, prospective motor responses, and prior experience. Spontaneous cortical activity has been proposed to play an important part in maintaining these ongoing, internal representations, although its functional role is not well understood. One spontaneous signal being intensely investigated in the human brai...

  12. Voluntary breath holding affects spontaneous brain activity measured by magnetoencephalography

    NARCIS (Netherlands)

    Schellart, N. A.; Reits, D.

    1999-01-01

    Spontaneous brain activity was measured by multichannel magnetoencephalography (MEG) during voluntary breath holds. Significant changes in the activity are limited to the alpha rhythm: 0.25 Hz frequency increase and narrowing of the peak. The area of alpha activity shifts slightly toward (fronto-)

  13. Spontaneous Electrical Activity in the Nervous System and its ...

    African Journals Online (AJOL)

    The present study was carried out to examine the effects of biogenic amines on the spontaneous electrical activity of the nervous system in the silkworm Bombyx mori. The activity recorded from different segments of the ventral nerve cord differed in the frequency and number of spike categories firing. The activity was highest ...

  14. Mesoscale Architecture Shapes Initiation and Richness of Spontaneous Network Activity.

    Science.gov (United States)

    Okujeni, Samora; Kandler, Steffen; Egert, Ulrich

    2017-04-05

    Spontaneous activity in the absence of external input, including propagating waves of activity, is a robust feature of neuronal networks in vivo and in vitro The neurophysiological and anatomical requirements for initiation and persistence of such activity, however, are poorly understood, as is their role in the function of neuronal networks. Computational network studies indicate that clustered connectivity may foster the generation, maintenance, and richness of spontaneous activity. Since this mesoscale architecture cannot be systematically modified in intact tissue, testing these predictions is impracticable in vivo Here, we investigate how the mesoscale structure shapes spontaneous activity in generic networks of rat cortical neurons in vitro In these networks, neurons spontaneously arrange into local clusters with high neurite density and form fasciculating long-range axons. We modified this structure by modulation of protein kinase C, an enzyme regulating neurite growth and cell migration. Inhibition of protein kinase C reduced neuronal aggregation and fasciculation of axons, i.e., promoted uniform architecture. Conversely, activation of protein kinase C promoted aggregation of neurons into clusters, local connectivity, and bundling of long-range axons. Supporting predictions from theory, clustered networks were more spontaneously active and generated diverse activity patterns. Neurons within clusters received stronger synaptic inputs and displayed increased membrane potential fluctuations. Intensified clustering promoted the initiation of synchronous bursting events but entailed incomplete network recruitment. Moderately clustered networks appear optimal for initiation and propagation of diverse patterns of activity. Our findings support a crucial role of the mesoscale architectures in the regulation of spontaneous activity dynamics. SIGNIFICANCE STATEMENT Computational studies predict richer and persisting spatiotemporal patterns of spontaneous activity in

  15. HALF-LIVES OF LONG-LIVED α-DECAY, β-DECAY, ββ-DECAY AND SPONTANEOUS FISSION NUCLIDES

    International Nuclear Information System (INIS)

    HOLDEN, N.E.

    2001-01-01

    In his review of radionuclides for dating purposes, Roth noted that there were a large number of nuclides, normally considered ''stable'' but which are radioactive with a very long half-life. Roth suggested that I review the data on the half-life values of these long-lived nuclides for a discussion session at the next meeting. These half-life values for long-lived nuclides include those due to various decay modes, α-decay, β-decay, electron capture decay, ββ-decay and spontaneous fission decay. This report is preliminary but will provide a quick overview of the extensive table of data on the recommendations from that review

  16. Spatial diversity of spontaneous activity in the cortex

    Directory of Open Access Journals (Sweden)

    Andrew Yong-Yi Tan

    2015-09-01

    Full Text Available The neocortex is a layered sheet across which a basic organization is thought to widely apply. The variety of spontaneous activity patterns is similar throughout the cortex, consistent with the notion of a basic cortical organization. However, the basic organization is only an outline which needs adjustments and additions to account for the structural and functional diversity across cortical layers and areas. Such diversity suggests that spontaneous activity is spatially diverse in any particular behavioral state. Accordingly, this review summarizes the laminar and areal diversity in cortical activity during fixation and slow oscillations, and the effects of attention, anesthesia and plasticity on the cortical distribution of spontaneous activity. Among questions that remain open, characterizing the spatial diversity in spontaneous membrane potential may help elucidate how differences in circuitry among cortical regions supports their varied functions. More work is also needed to understand whether cortical spontaneous activity not only reflects cortical circuitry, but also contributes to determining the outcome of plasticity, so that it is itself a factor shaping the functional diversity of the cortex.

  17. Progress in fission product nuclear data

    International Nuclear Information System (INIS)

    Lammer, M.

    1982-07-01

    This is the eighth issue of a report series on Fission Product Nuclear Data (FPND) which is published by the Nuclear Data Section (NDS) of the International Atomic Energy Agency (IAEA). The purpose of this series is to inform scientists working on FPND, or using such data, about all activities in this field which are planned, ongoing, or have recently been completed. The main part of this report consists of unaltered original contributions which the authors have sent to IAEA/NDS. Therefore, the IAEA cannot be held responsible for the information contained nor for any consequences resulting from the use of this information. The present issue contains also a section with some recent references relative to fission product nuclear data, which were not covered by the contributions submitted. The types of activities being included in this report are measurements, compilations and evaluations of: Fission product yields (neutron induced and spontaneous fission); Neutron reaction cross sections of fission products; Data related to the radioactive decay of fission products; Delayed neutron data of fission products; and lumped fission product data (decay heat, absorption etc.). The seventh issue of this series has been published in July 1981 as INDC(NDS)-116. The present issue includes contributions which were received by NDS between 1 August 1981 and 15 June 1982

  18. Progress in fission product nuclear data

    International Nuclear Information System (INIS)

    Lammer, M.

    1983-08-01

    This is the ninth issue of a report series on Fission Product Nuclear Data (FPND) which is published by the Nuclear Data Section (NDS) of the International Atomic Energy Agency (IAEA). The purpose of this series is to inform scientists working on FPND, or using such data, about all activities in this field which are planned, ongoing, or have recently been completed. The main part of this report consists of unaltered original contributions which the authors have sent to IAEA/NDS. The present issue contains also a section with some recent references relative to fission product nuclear data, which were not covered by the contributions submitted. The types of activities being included in this report are measurements, compilations and evaluations of: Fission product yields (neutron induced and spontaneous fission); Neutron reaction cross sections of fission products; Data related to the radioactive decay of fission products; Delayed neutron data of fission products; and lumped fission product data (decay heat, absorption etc.). The eighth issue of this series has been published in July 1982 as INDC(NDS)-130. The present issue includes contributions which were received by NDS between 1 August 1982 and 25 June 1983

  19. Progress in fission product nuclear data

    International Nuclear Information System (INIS)

    Lammer, M.

    1981-06-01

    This is the seventh issue of a report series on Fission Product Nuclear Data (FPND) which is published by the Nuclear Data Section (NDS) of the International Atomic Energy Agency (IAEA). The purpose of this series is to inform scientists working on FPND, or using such data, about all activities in this field which are planned, ongoing, or have recently been completed. The present issue contains also a section with some recent references relative to fission product nuclear data, which were not covered by the contributions submitted. The types of activities being included in this report are measurements, compilations and evaluations of: fission product yields (neutron induced and spontaneous fission); neutron reaction cross sections of fission products; data related to the radioactive decay of fission products; delayed neutron data of fission products; and lumped fission product data (decay heat, absorption etc.). The sixth issue of this series has been published in June 1980 as INDC(NDS)-113/G+P. The present issue includes contributions which were received by NDS between 1 August 1980 and 25 May 1981

  20. Activation product analysis in a mixed sample containing both fission and neutron activation products

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, Samuel S.; Clark, Sue B.; Eggemeyer, Tere A.; Finn, Erin C.; Hines, C. Corey; King, Mathew D.; Metz, Lori A.; Morley, Shannon M.; Snow, Mathew S.; Wall, Donald E.; Seiner, Brienne N.

    2017-11-02

    Activation analysis of gold (Au) is used to estimate neutron fluence resulting from a criticality event; however, such analyses are complicated by simultaneous production of other gamma-emitting fission products. Confidence in neutron fluence estimates can be increased by quantifying additional activation products such as platinum (Pt), tantalum (Ta), and tungsten (W). This work describes a radiochemical separation procedure for the determination of these activation products. Anion exchange chromatography is used to separate anionic forms of these metals in a nitric acid matrix; thiourea is used to isolate the Au and Pt fraction, followed by removal of the Ta fraction using hydrogen peroxide. W, which is not retained on the first anion exchange column, is transposed to an HCl/HF matrix to enhance retention on a second anion exchange column and finally eluted using HNO3/HF. Chemical separations result in a reduction in the minimum detectable activity by a factor of 287, 207, 141, and 471 for 182Ta, 187W, 197Pt, and 198Au respectively, with greater than 90% recovery for all elements. These results represent the highest recoveries and lowest minimum detectable activities for 182Ta, 187W, 197Pt, and 198Au from mixed fission-activation product samples to date, enabling considerable refinement in the measurement uncertainties for neutron fluences in highly complex sample matrices.

  1. Uncovering intrinsic modular organization of spontaneous brain activity in humans.

    Directory of Open Access Journals (Sweden)

    Yong He

    Full Text Available The characterization of topological architecture of complex brain networks is one of the most challenging issues in neuroscience. Slow (<0.1 Hz, spontaneous fluctuations of the blood oxygen level dependent (BOLD signal in functional magnetic resonance imaging are thought to be potentially important for the reflection of spontaneous neuronal activity. Many studies have shown that these fluctuations are highly coherent within anatomically or functionally linked areas of the brain. However, the underlying topological mechanisms responsible for these coherent intrinsic or spontaneous fluctuations are still poorly understood. Here, we apply modern network analysis techniques to investigate how spontaneous neuronal activities in the human brain derived from the resting-state BOLD signals are topologically organized at both the temporal and spatial scales. We first show that the spontaneous brain functional networks have an intrinsically cohesive modular structure in which the connections between regions are much denser within modules than between them. These identified modules are found to be closely associated with several well known functionally interconnected subsystems such as the somatosensory/motor, auditory, attention, visual, subcortical, and the "default" system. Specifically, we demonstrate that the module-specific topological features can not be captured by means of computing the corresponding global network parameters, suggesting a unique organization within each module. Finally, we identify several pivotal network connectors and paths (predominantly associated with the association and limbic/paralimbic cortex regions that are vital for the global coordination of information flow over the whole network, and we find that their lesions (deletions critically affect the stability and robustness of the brain functional system. Together, our results demonstrate the highly organized modular architecture and associated topological properties in

  2. First inverse-kinematics fission measurements in a gaseous active target

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Tajes, C., E-mail: rodriguez@ganil.fr [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DRF-CNRS/IN2P3, Bd. Henri Becquerel, 14076 Caen (France); Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain); Farget, F. [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DRF-CNRS/IN2P3, Bd. Henri Becquerel, 14076 Caen (France); Acosta, L. [Departamento de Ciencias Integradas, Universidad de Huelva, E-21071 Huelva (Spain); Alvarez-Pol, H. [Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain); Babo, M.; Boulay, F. [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DRF-CNRS/IN2P3, Bd. Henri Becquerel, 14076 Caen (France); Caamaño, M. [Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain); Damoy, S. [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DRF-CNRS/IN2P3, Bd. Henri Becquerel, 14076 Caen (France); Fernández-Domínguez, B. [Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain); Galaviz, D. [Centro de Física Nuclear da Universidade de Lisboa, CFNUL, 1649-003 Lisboa (Portugal); Grinyer, G.F.; Grinyer, J. [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DRF-CNRS/IN2P3, Bd. Henri Becquerel, 14076 Caen (France); Harakeh, M.N. [KVI-CART, University of Groningen, Zernikelaan 25, NL-9747 AA Groningen (Netherlands); Konczykowski, P. [Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain); and others

    2017-02-15

    The fission of a variety of actinides was induced by fusion and transfer reactions between a {sup 238}U beam and {sup 12}C nuclei, in the active target MAYA. The performance of MAYA was studied, as well as its capability to reconstruct the fission-fragment trajectories. Furthermore, a full characterization of the different transfer reactions was achieved, and the populated excitation-energy distributions were investigated as a function of the kinetic energy in the entrance channel. The ratio between transfer- and fusion-induced fission cross-sections was also determined, in order to investigate the competition between both reaction types and its evolution with the incident energy. The experimental results will be discussed with a view to forthcoming radioactive-ion beam facilities, and next-generation active-target setups.

  3. Behavioral Modulation by Spontaneous Activity of Dopamine Neurons

    Directory of Open Access Journals (Sweden)

    Toshiharu Ichinose

    2017-12-01

    Full Text Available Dopamine modulates a variety of animal behaviors that range from sleep and learning to courtship and aggression. Besides its well-known phasic firing to natural reward, a substantial number of dopamine neurons (DANs are known to exhibit ongoing intrinsic activity in the absence of an external stimulus. While accumulating evidence points at functional implications for these intrinsic “spontaneous activities” of DANs in cognitive processes, a causal link to behavior and its underlying mechanisms has yet to be elucidated. Recent physiological studies in the model organism Drosophila melanogaster have uncovered that DANs in the fly brain are also spontaneously active, and that this activity reflects the behavioral/internal states of the animal. Strikingly, genetic manipulation of basal DAN activity resulted in behavioral alterations in the fly, providing critical evidence that links spontaneous DAN activity to behavioral states. Furthermore, circuit-level analyses have started to reveal cellular and molecular mechanisms that mediate or regulate spontaneous DAN activity. Through reviewing recent findings in different animals with the major focus on flies, we will discuss potential roles of this physiological phenomenon in directing animal behaviors.

  4. Patterns of Spontaneous Magnetoencephalographic Activity in Schizophrenic Patients

    OpenAIRE

    Siekmeier, Peter J.; Stufflebeam, Steven M.

    2010-01-01

    Magnetoencephalography (MEG) non-invasively measures the magnetic fields produced by the brain. Pertinent research articles from 1993 to 2009 that measured spontaneous, whole-head MEG activity in schizophrenic patients were reviewed. Data on localization of oscillatory activity and correlation of these findings with psychotic symptoms are summarized. While the variety of measures used by different research groups makes a quantitative meta-analysis difficult, it appears that MEG activity in pa...

  5. Modulating spontaneous brain activity using repetitive transcranial magnetic stimulation

    NARCIS (Netherlands)

    van der Werf, Y.D.; Sanz-Arigita, E.J.; Menning, S.; van den Heuvel, O.A.

    2010-01-01

    Background: When no specific stimulus or task is presented, spontaneous fluctuations in brain activity occur. Brain regions showing such coherent fluctuations are thought to form organized networks known as 'resting-state' networks, a main representation of which is the default mode network.

  6. Presynaptic Spontaneous Activity Enhances the Accuracy of Latency Coding

    Czech Academy of Sciences Publication Activity Database

    Leváková, Marie; Tamborrino, M.; Košťál, Lubomír; Lánský, Petr

    2016-01-01

    Roč. 28, č. 10 (2016), s. 2162-2180 ISSN 0899-7667 R&D Projects: GA MŠk 7AMB15AT010; GA ČR(CZ) GA15-08066S Institutional support: RVO:67985823 Keywords : neural coding * first-spike latency * spontaneous activity Subject RIV: FH - Neurology Impact factor: 1.938, year: 2016

  7. Spontaneous neutrophil activation in HTLV-1 infected patients

    Directory of Open Access Journals (Sweden)

    Jaqueline B. Guerreiro

    Full Text Available Human T cell lymphotropic Virus type-1 (HTLV-1 induces lymphocyte activation and proliferation, but little is known about the innate immune response due to HTLV-1 infection. We evaluated the percentage of neutrophils that metabolize Nitroblue tetrazolium (NBT to formazan in HTLV-1 infected subjects and the association between neutrophil activation and IFN-gamma and TNF-alpha levels. Blood was collected from 35 HTLV-1 carriers, from 8 patients with HAM/TSP (HTLV-1- associated myelopathy; 22 healthy individuals were evaluated for spontaneous and lipopolysaccharide (LPS-stimulated neutrophil activity (reduction of NBT to formazan. The production of IFN-gamma and TNF-alpha by unstimulated mononuclear cells was determined by ELISA. Spontaneous NBT levels, as well as spontaneous IFN-gamma and TNF-alpha production, were significantly higher (p<0.001 in HTLV-1 infected subjects than in healthy individuals. A trend towards a positive correlation was noted, with increasing percentage of NBT positive neutrophils and levels of IFN-gamma. The high IFN-gamma producing HTLV-1 patient group had significantly greater NBT than healthy controls, 43±24% and 17±4.8% respectively (p< 0.001, while no significant difference was observed between healthy controls and the low IFN-gamma-producing HTLV-1 patient group (30±20%. Spontaneous neutrophil activation is another marker of immune perturbation resulting from HTLV-1 infection. In vivo activation of neutrophils observed in HTLV-1 infected subjects is likely to be the same process that causes spontaneous IFN-gamma production, or it may partially result from direct IFN-gamma stimulation.

  8. Spontaneous physical activity protects against fat mass gain

    OpenAIRE

    Teske, Jennifer A.; Billington, Charles J.; Kuskowski, Michael A.; Kotz, Catherine M.

    2011-01-01

    It is unclear whether elevated spontaneous physical activity (SPA, very low-intensity physical activity) positively influences body composition long-term. Objective We determined whether SPA and caloric intake were differentially related to the growth curve trajectories of body weight, FM and FFM between obesity resistant and Sprague-Dawley rats at specific age intervals. Design and Subjects Body composition, SPA and caloric intake were measured in selectively-bred obesity resistant and out-b...

  9. Application of the activation analysis using the method of retarded fission neutrons counting for the determination of some fissionable nuclides

    International Nuclear Information System (INIS)

    Armelin, M.J.A.

    1984-01-01

    A system for the detection and counting of delayed neutrons which allows the analysis of some fissile and fertile nuclides, in samples of milligram size, was developed. This was applied for the analysis of natural uranium and thorium and also for determining the 235 U/ 238 U ratio in non-irradiated samples which contain uranium with different degrees of enrichment in 235 U. The spectrum of activated neutrons was varied in order to discriminate the nuclides, by covering or not the sample with a material (cadmium or boron) able to absorb low energy neutrons. Determination of 235 U/ 238 U ratios, through the number of delayed neutrons, was made by drawing a calibration curve using standards ranging from 0.5% to 93% on 235 U; the accuracy of the method was also examined. In a first step, conditions for a simultaneous and non-destructive analysis of uranium and thorium were developed. The interference between these two nuclides was studied, using simulated samples. Real samples were provided by Nuclemon and IAEA. For samples with uranium concentration in the range of percentages and thorium concentration of some ppm, uranium interferes in the determination of thorium through the non-destructive analytical method. For this case, a fast and quantitative chemical method was studied which allows for the separation of thorium from uranium before the determination of throrium concentration by counting the delayed fission neutrons. It was found that the results obtained by both destructive and non-destructive methods are very consistent and can be considered statistically equivalent within a confidence level of 95%. (Author) [pt

  10. Ensemble spontaneous activity alterations detected by CISA approach.

    Science.gov (United States)

    Boudaoud, Sofiane; Rix, Hervé; Meste, Olivier; Cazals, Yves

    2007-01-01

    In this paper, we propose a method for detecting alterations in the Ensemble Spontaneous Activity (ESA), a random signal representing the composite spontaneous contribution of the auditory nerve recorded on the round window. The proposed method is based on shape analysis of the ESA amplitude histogram. For this task, we use a recent approach, the Corrected Integral Shape Averaging (CISA). Using this approach, a shape clustering algorithm is proposed to classify healthy and pathological ESA signals generated by a recent ESA model. This model allows a precise simulation of neural mechanisms occurring in the auditory nerve. The obtained results demonstrate that this shape analysis is very sensitive for detecting a small number of fibers with correlated firing, supposed to occur during a particular type of tinnitus. In comparison, the classical spectral index fails in this detection.

  11. An improved technique for fission track dating

    International Nuclear Information System (INIS)

    Zhao Yunlong; Wu Zhaohui; Xia Yuliang

    1996-01-01

    The necessity of improving the fission track dating (FTD) technique both at home and abroad is illustrated. The ways of making such improvement are also proposed. It is suggested to calibrate the constant b value of the uranium standard glass by using the method of fission products activity. The 3 kinds of uranium standard glass which have been calibrated are NBS SRM962a, UB 1 and UB 2 . An established new method σ·Φ ρ d /b, to measure neutron fluence, avoids the influence of the varying neutron spectrum on measuring neutron fluence. The improved etching technique for fission tracks in zircon adopted a two-step method which includes the molten alkali system etching using NaOH + KOH and the mixed acid system etching using HNO 3 + HF; this technique results in adequate track etching, increased track clarity and less interference. In this way the intensity of tracks is authentically reflected. Dividing angular zone in accordance with the angular distribution of spontaneous fission track on the crystal surface of minerals to count the tracks and using the improved etching technique to remove the non-uniform angular distribution of spontaneous fission tracks in zircon, ensure the accuracy of tracks count. The improved FTD techniques were used to finish Laboratory Standardized Calibration. The tests using international FTD age standards samples have proved that above mentioned techniques are reliable and practical in obtaining the accurate FTD data. (8 tabs.; 3 figs.)

  12. Spontaneous cortical activity is transiently poised close to criticality.

    Directory of Open Access Journals (Sweden)

    Gerald Hahn

    2017-05-01

    Full Text Available Brain activity displays a large repertoire of dynamics across the sleep-wake cycle and even during anesthesia. It was suggested that criticality could serve as a unifying principle underlying the diversity of dynamics. This view has been supported by the observation of spontaneous bursts of cortical activity with scale-invariant sizes and durations, known as neuronal avalanches, in recordings of mesoscopic cortical signals. However, the existence of neuronal avalanches in spiking activity has been equivocal with studies reporting both its presence and absence. Here, we show that signs of criticality in spiking activity can change between synchronized and desynchronized cortical states. We analyzed the spontaneous activity in the primary visual cortex of the anesthetized cat and the awake monkey, and found that neuronal avalanches and thermodynamic indicators of criticality strongly depend on collective synchrony among neurons, LFP fluctuations, and behavioral state. We found that synchronized states are associated to criticality, large dynamical repertoire and prolonged epochs of eye closure, while desynchronized states are associated to sub-criticality, reduced dynamical repertoire, and eyes open conditions. Our results show that criticality in cortical dynamics is not stationary, but fluctuates during anesthesia and between different vigilance states.

  13. Spontaneous activity in the statoacoustic ganglion of the chicken embryo.

    Science.gov (United States)

    Jones, T A; Jones, S M

    2000-03-01

    Statoacoustic ganglion cells in the mature bird include neurons that are responsive to sound (auditory) and those that are not (nonauditory). Those that are nonauditory have been shown to innervate an otolith organ, the macula lagena, whereas auditory neurons innervate the basilar papilla. In the present study, single-unit recordings of statoacoustic ganglion cells were made in embryonic (E19, mean = 19.2 days of incubation) and hatchling (P6-P14, mean = 8.6 days posthatch) chickens. Spontaneous activity from the two age groups was compared with developmental changes. Activity was evaluated for 47 auditory, 11 nonauditory, and 6 undefined eighth nerve neurons in embryos and 29 auditory, 26 nonauditory, and 1 undefined neurons in hatchlings. For auditory neurons, spontaneous activity displayed an irregular pattern [discharge interval coefficient of variation (CV) was >0.5, mean CV for embryos was 1.46 +/- 0.58 and for hatchlings was 1.02 +/- 0.25; means +/- SD]. Embryonic discharge rates ranged from 0.05 to 97.6 spikes per second (sp/s) for all neurons (mean 18.6 +/- 16.9 sp/s). Hatchling spontaneous rates ranged from 1.2 to 185.2 sp/s (mean 66.5 +/- 39.6 sp/s). Discharge rates were significantly higher for hatchlings (P embryonic auditory neurons displayed long silent periods between irregular bursts of neural activity, a feature not seen posthatch. All regular bursting discharge patterns were correlated with heart rate in both embryos and hatchlings. Preferred intervals were visible in the time interval histograms (TIHs) of only one embryonic neuron in contrast to 55% of the neurons in posthatch animals. Generally, the embryonic auditory TIH displayed a modified quasi-Poisson distribution. Nonauditory units generally displayed regular (CV 0.5) activity and Gaussian and modified-Gaussian TIHs. Long silent periods or bursting patterns were not a characteristic of embryonic nonauditory neurons. CV varied systematically as a function of discharge rate in nonauditory

  14. Recruitment of Perisomatic Inhibition during Spontaneous Hippocampal Activity In Vitro.

    Directory of Open Access Journals (Sweden)

    Anna Beyeler

    Full Text Available It was recently shown that perisomatic GABAergic inhibitory postsynaptic potentials (IPSPs originating from basket and chandelier cells can be recorded as population IPSPs from the hippocampal pyramidal layer using extracellular electrodes (eIPSPs. Taking advantage of this approach, we have investigated the recruitment of perisomatic inhibition during spontaneous hippocampal activity in vitro. Combining intracellular and extracellular recordings from pyramidal cells and interneurons, we confirm that inhibitory signals generated by basket cells can be recorded extracellularly, but our results suggest that, during spontaneous activity, eIPSPs are mostly confined to the CA3 rather than CA1 region. CA3 eIPSPs produced the powerful time-locked inhibition of multi-unit activity expected from perisomatic inhibition. Analysis of the temporal dynamics of spike discharges relative to eIPSPs suggests significant but moderate recruitment of excitatory and inhibitory neurons within the CA3 network on a 10 ms time scale, within which neurons recruit each other through recurrent collaterals and trigger powerful feedback inhibition. Such quantified parameters of neuronal interactions in the hippocampal network may serve as a basis for future characterisation of pathological conditions potentially affecting the interactions between excitation and inhibition in this circuit.

  15. Neutron emission anisotropy in fission

    OpenAIRE

    CHIETERA A.; STUTTGE L.; GOENNENWEIN F.; KOPATCH Y.; MUTTERER M.; GUSEVA I.; GAGARSKI A.; CHERNYSHEVA E; DORVAUX O; HAMBSCH Franz-Josef; HANAPPE F.; MEZENTSEVAH Z.; TELEZHNIKOVCH S.

    2015-01-01

    Experimental neutron angular distributions are investigated in the spontaneous fission process of 252Cf. The CORA experiment, presented in this paper, has the aim to study neutron angular correlations in order to elucidate the neutron emission mechanisms in the fission process. The experimental setup is composed by the CODIS fission chamber and the DEMON neutron multidetector. The development of a simulation toolkit based on GEANT4 and ROOT adopted as strategy to investigate the emission of t...

  16. Copper is an endogenous modulator of neural circuit spontaneous activity.

    Science.gov (United States)

    Dodani, Sheel C; Firl, Alana; Chan, Jefferson; Nam, Christine I; Aron, Allegra T; Onak, Carl S; Ramos-Torres, Karla M; Paek, Jaeho; Webster, Corey M; Feller, Marla B; Chang, Christopher J

    2014-11-18

    For reasons that remain insufficiently understood, the brain requires among the highest levels of metals in the body for normal function. The traditional paradigm for this organ and others is that fluxes of alkali and alkaline earth metals are required for signaling, but transition metals are maintained in static, tightly bound reservoirs for metabolism and protection against oxidative stress. Here we show that copper is an endogenous modulator of spontaneous activity, a property of functional neural circuitry. Using Copper Fluor-3 (CF3), a new fluorescent Cu(+) sensor for one- and two-photon imaging, we show that neurons and neural tissue maintain basal stores of loosely bound copper that can be attenuated by chelation, which define a labile copper pool. Targeted disruption of these labile copper stores by acute chelation or genetic knockdown of the CTR1 (copper transporter 1) copper channel alters the spatiotemporal properties of spontaneous activity in developing hippocampal and retinal circuits. The data identify an essential role for copper neuronal function and suggest broader contributions of this transition metal to cell signaling.

  17. Patterns of spontaneous magnetoencephalographic activity in patients with schizophrenia.

    Science.gov (United States)

    Siekmeier, Peter J; Stufflebeam, Steven M

    2010-06-01

    Magnetoencephalography noninvasively measures the magnetic fields produced by the brain. Pertinent research articles from 1993 to 2009 that measured spontaneous, whole-head magnetoencephalography activity in patients with schizophrenia were reviewed. Data on localization of oscillatory activity and correlation of these findings with psychotic symptoms are summarized. Although the variety of measures used by different research groups makes a quantitative meta-analysis difficult, it appears that magnetoencephalography activity in patients may exhibit identifiable patterns, defined by topographic organization and frequency band. Specifically, 11 of the 12 studies showed increased theta (4-8 Hz) and delta (1-4 Hz) band oscillations in the temporal lobes of patients; of the 10 studies that examined the relationship between oscillatory activity and symptomatology, 8 found a positive correlation between temporal lobe theta activity and positive schizophrenic symptoms. Abnormally high frontal delta activity was not seen. These findings are analyzed in comparison with the electroencephalogram literature on schizophrenics, and possible confounds (e.g., medication effects) are discussed. In the future, magnetoencephalography might be used to assist in diagnosis or might be fruitfully used in conjunction with new neuroscience research approaches such as computational modeling, which may be able to link oscillatory activity and cellular-level pathology.

  18. Cloning and characterization of shk2, a gene encoding a novel p21-activated protein kinase from fission yeast.

    Science.gov (United States)

    Yang, P; Kansra, S; Pimental, R A; Gilbreth, M; Marcus, S

    1998-07-17

    We describe the characterization of a novel gene, shk2, encoding a second p21(cdc42/rac)-activated protein kinase (PAK) homolog in fission yeast. Like other known PAKs, Shk2 binds to Cdc42 in vivo and in vitro. While overexpression of either shk2 or cdc42 alone does not impair growth of wild type fission yeast cells, cooverexpression of the two genes is toxic and leads to highly aberrant cell morphology, providing evidence for functional interaction between Cdc42 and Shk2 proteins in vivo. Fission yeast shk2 null mutants are viable and exhibit no obvious phenotypic defects. Overexpression of shk2 restores viability and normal morphology but not full mating competence to fission yeast cells carrying a shk1 null mutation. Additional genetic data suggest that Shk2, like Cdc42 and Shk1, participates in Ras-dependent morphological control and mating response pathways in fission yeast. We also show that overexpression of byr2, a gene encoding a Ste11/MAPK kinase kinase homolog, suppresses the mating defect of cells partially defective for Shk1 function, providing evidence of a link between PAKs and mitogen-activated protein kinase signaling in fission yeast. Taken together, our results suggest that Shk2 is partially overlapping in function with Shk1, with Shk1 being the dominant protein in function.

  19. Air activity variations as estimation of inhalation dose for the gases fission products

    International Nuclear Information System (INIS)

    Mousavi Shirazi, A; Jahanfarnia, G.; Rahgoshay, M.; Aghanajafi, C.; Sardari, D.

    2008-01-01

    This article presents that dissolved impurities are responsible for water activity and the release of fission gases Radon and Thoron into the reactor hall atmosphere. In normal operation of the reactor at 400 kilowatts, wide fluctuations in airborne activity (gross beta) between 15,000-200,000 dpm/m 3 have been noticed. The aerosol concentration, reactor hall temperature, relative humidity and ventilation rate are the factors influencing the levels of airborne activity in the reactor hall atmosphere. These parameters are discussed in relation to the observed air activities. The diffusion coefficient of the decay products and the unattached fraction of the decay products are necessary parameters for the estimation of lung dose. These have been measured. Internal exposure results from the deposition of radioactive material within the body through inhalation, ingestion and absorption. A recent study has indicated that inhalation is the main route of entry, and nearly 75% of the cases of internal contamination are attributable to inhalation. It has been demonstrated that the inert fission gases like Radon and Thoron do not contribute significantly to the dose due to inhalation to the working personnel in reactors, but their decay products which are particulate β emitters, contribute significant inhalation dose

  20. Purification of moderately active wastewater solutions of fission products by co-precipitation

    International Nuclear Information System (INIS)

    Cohen, Pierre; Amavis, Rene; Vaccarezza, Jacques

    1961-01-01

    The authors report a study which aimed at developing a purification treatment for moderately active wastewater solutions of fission products by using co-precipitation. As the considered wastewater solutions are acid, the authors first studied different treatments which do not require an alkaline neutralisation. As results were not satisfying in terms of efficiency, the authors studied the best carryover conditions of strontium 90 by a calcium or strontium phosphate, and then studied the influence of a second precipitation of nickel ferrocyanide on the decontamination of caesium and other beta emitters. The wastewater solutions used is this study come from a plutonium extraction pilot plant in Fontenay-aux-Roses

  1. Neutron activation analysis (NAA), radioisotope production via neutron activation (PNA) and fission product gas-jet (GJA)

    Energy Technology Data Exchange (ETDEWEB)

    Gaeggeler, H.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1996-11-01

    Three different non-diffractive applications of neutrons are outlined, neutron activation analysis, production of radionuclides, mostly for medical applications, and production of short-lived fission nuclides with a so-called gas-jet. It is shown that all three devices may be incorporated into one single insert at SINQ due to their different requests with respect to thermal neutron flux. Some applications of these three facilities are summarized. (author) 3 figs., 1 tab., 8 refs.

  2. Spontaneous recombinase activity of Cre-ERT2 in vivo.

    Science.gov (United States)

    Kristianto, Jasmin; Johnson, Michael G; Zastrow, Ryley K; Radcliff, Abigail B; Blank, Robert D

    2017-06-01

    Inducible Cre-ERT recombinase technology is widely used for gene targeting studies. The second generation of inducible Cre-ERT recombinase, hemizygous B6.129S-Tg(UBC-cre/ERT2)1Ejb/J (hereafter abbreviated as Cre-ERT2), a fusion of a mutated estrogen receptor and Cre recombinase, was engineered to be more efficient and specific than the original Cre-ERT. The putative mechanism of selective Cre-mediated recombination is Cre sequestration in the cytoplasm in the basal state with translocation to the nucleus only in the presence of tamoxifen. We utilized both a reporter mouse (B6.129 (Cg)-Gt(ROSA)26Sor tm4(ACTB-tdTomato,-EGFP)Luo /J) and endothelin converting enzyme-1 floxed transgenic mouse line to evaluate Cre-ERT2 activity. We observed spontaneous Cre activity in both settings. Unintended Cre activity is a confounding factor that has a potentially large impact on data interpretation. Thus, it is important to consider background Cre activity in experimental design.

  3. Membrane fission by protein crowding.

    Science.gov (United States)

    Snead, Wilton T; Hayden, Carl C; Gadok, Avinash K; Zhao, Chi; Lafer, Eileen M; Rangamani, Padmini; Stachowiak, Jeanne C

    2017-04-18

    Membrane fission, which facilitates compartmentalization of biological processes into discrete, membrane-bound volumes, is essential for cellular life. Proteins with specific structural features including constricting rings, helical scaffolds, and hydrophobic membrane insertions are thought to be the primary drivers of fission. In contrast, here we report a mechanism of fission that is independent of protein structure-steric pressure among membrane-bound proteins. In particular, random collisions among crowded proteins generate substantial pressure, which if unbalanced on the opposite membrane surface can dramatically increase membrane curvature, leading to fission. Using the endocytic protein epsin1 N-terminal homology domain (ENTH), previously thought to drive fission by hydrophobic insertion, our results show that membrane coverage correlates equally with fission regardless of the hydrophobicity of insertions. Specifically, combining FRET-based measurements of membrane coverage with multiple, independent measurements of membrane vesiculation revealed that fission became spontaneous as steric pressure increased. Further, fission efficiency remained equally potent when helices were replaced by synthetic membrane-binding motifs. These data challenge the view that hydrophobic insertions drive membrane fission, suggesting instead that the role of insertions is to anchor proteins strongly to membrane surfaces, amplifying steric pressure. In line with these conclusions, even green fluorescent protein (GFP) was able to drive fission efficiently when bound to the membrane at high coverage. Our conclusions are further strengthened by the finding that intrinsically disordered proteins, which have large hydrodynamic radii yet lack a defined structure, drove fission with substantially greater potency than smaller, structured proteins.

  4. Using Electronic Neutron Generators in Active Interrogation to Detect Shielded Fissionable Material

    Science.gov (United States)

    Chichester, David L.; Seabury, Edward H.

    2009-04-01

    Experiments have been performed at Idaho National Laboratory to study methodology and instrumentation for performing neutron active interrogation die-away analyses for the purpose of detecting shielded fissionable material. Here we report initial work using a portable DT electronic neutron generator with a 3He neutron detector to detect shielded fissionable material including enriched uranium and reactor grade plutonium. Measurements have been taken of bare material as well as of material hidden within a large plywood cube. Results from this work have demonstrated the efficacy of the die-away neutron measurement technique for quickly detecting the presence of special nuclear material hidden within plywood shields by analyzing the time dependent neutron signals in-between neutron generator pulses. Using a DT electronic neutron generator operating at 300 Hz with a yield of approximately 0.36 times 108 neutrons per second, 2.2 kg of enriched uranium hidden within a 61 cm times 61 cm times 71 cm volume of plywood was positively detected with a measurement signal 2-sigma above the passive background within 1 second. Similarly, for a 500 second measurement period a lower detection limit approaching the gram level could be expected with the same simple set-up.

  5. Angular Momentum in Fission

    Science.gov (United States)

    Gönnenwein, F.; Bunakov, V.; Dorvaux, O.; Gagarski, A.; Guseva, I.; Hanappe, F.; Kadmensky, S.; von Kalben, J.; Khlebnikov, S.; Kinnard, V.; Kopatch, Yu.; Mutterer, M.; Nesvizhevsky, V.; Petrov, G.; Prokhorova, E.; Rubchenya, V.; Sillanpää, M.; Simpson, G.; Sokolov, V.; Soldner, T.; Stuttgé, L.; Tiourine, G.; Trzaska, W.; Tsekhanovich, I.; Wagemans, C.; Wollersheim, H.-J.; Zavarukhina, T.; Zimmer, O.

    2008-04-01

    Three novel experiments in spontaneous and thermal neutron induced fission all with a bearing on angular momentum in fission are reviewed. In the first experiment it was observed that, in the reaction 235U(n, f) with incident polarized cold neutrons, the nucleus undergoing scission is rotating. This was inferred from the shift in angular distributions of ternary particles being dependent on the orientation of neutron spin. In the second study the properties of the angular momentum of spherical fission fragments was investigated. Current theories trace the spin of fragments to their deformations allowing for collective rotational vibrations at scission. However, in particular the spherical 132Te isotope exhibits a large spin at variance with theory. Exploiting the specific properties of cold deformed fission it could be proven that, for 132Te, single particle excitations instead of collective modes are responsible for the large spin observed. In a third project a pilot study was exploring the possibility to search for an evaporation of neutrons from fragments being anisotropic in their own cm-system. Due to fragment spin this anisotropy is claimed since decades to exist. It was so far never observed. A scheme has been devised and tested were triple coincidences between a fragment and two neutrons are evaluated in a way to bring the cm-anisotropy into the foreground while getting rid of the kinematical anisotropy in the lab-system due to evaporation from moving fragments. The test was run for spontaneous fission of 252Cf.

  6. New Perspectives on Spontaneous Brain Activity: Dynamic Networks and Energy Matter

    Science.gov (United States)

    Tozzi, Arturo; Zare, Marzieh; Benasich, April A.

    2016-01-01

    Spontaneous brain activity has received increasing attention as demonstrated by the exponential rise in the number of published article on this topic over the last 30 years. Such “intrinsic” brain activity, generated in the absence of an explicit task, is frequently associated with resting-state or default-mode networks (DMN)s. The focus on characterizing spontaneous brain activity promises to shed new light on questions concerning the structural and functional architecture of the brain and how they are related to “mind”. However, many critical questions have yet to be addressed. In this review, we focus on a scarcely explored area, specifically the energetic requirements and constraints of spontaneous activity, taking into account both thermodynamical and informational perspectives. We argue that the “classical” definitions of spontaneous activity do not take into account an important feature, that is, the critical thermodynamic energetic differences between spontaneous and evoked brain activity. Spontaneous brain activity is associated with slower oscillations compared with evoked, task-related activity, hence it exhibits lower levels of enthalpy and “free-energy” (i.e., the energy that can be converted to do work), thus supporting noteworthy thermodynamic energetic differences between spontaneous and evoked brain activity. Increased spike frequency during evoked activity has a significant metabolic cost, consequently, brain functions traditionally associated with spontaneous activity, such as mind wandering, require less energy that other nervous activities. We also review recent empirical observations in neuroscience, in order to capture how spontaneous brain dynamics and mental function can be embedded in a non-linear dynamical framework, which considers nervous activity in terms of phase spaces, particle trajectories, random walks, attractors and/or paths at the edge of the chaos. This takes us from the thermodynamic free-energy, to the realm

  7. Functional structure of spontaneous sleep slow oscillation activity in humans.

    Directory of Open Access Journals (Sweden)

    Danilo Menicucci

    Full Text Available BACKGROUND: During non-rapid eye movement (NREM sleep synchronous neural oscillations between neural silence (down state and neural activity (up state occur. Sleep Slow Oscillations (SSOs events are their EEG correlates. Each event has an origin site and propagates sweeping the scalp. While recent findings suggest a SSO key role in memory consolidation processes, the structure and the propagation of individual SSO events, as well as their modulation by sleep stages and cortical areas have not been well characterized so far. METHODOLOGY/PRINCIPAL FINDINGS: We detected SSO events in EEG recordings and we defined and measured a set of features corresponding to both wave shapes and event propagations. We found that a typical SSO shape has a transition to down state, which is steeper than the following transition from down to up state. We show that during SWS SSOs are larger and more locally synchronized, but less likely to propagate across the cortex, compared to NREM stage 2. Also, the detection number of SSOs as well as their amplitudes and slopes, are greatest in the frontal regions. Although derived from a small sample, this characterization provides a preliminary reference about SSO activity in healthy subjects for 32-channel sleep recordings. CONCLUSIONS/SIGNIFICANCE: This work gives a quantitative picture of spontaneous SSO activity during NREM sleep: we unveil how SSO features are modulated by sleep stage, site of origin and detection location of the waves. Our measures on SSOs shape indicate that, as in animal models, onsets of silent states are more synchronized than those of neural firing. The differences between sleep stages could be related to the reduction of arousal system activity and to the breakdown of functional connectivity. The frontal SSO prevalence could be related to a greater homeostatic need of the heteromodal association cortices.

  8. Tamsulosin modulates, but does not abolish the spontaneous activity in the guinea pig prostate gland.

    Science.gov (United States)

    Chakrabarty, Basu; Dey, Anupa; Lam, Michelle; Ventura, Sabatino; Exintaris, Betty

    2015-06-01

    To examine the effects of the α1A -adrenoceptor antagonist, tamsulosin, on spontaneous contractile and electrical activity in the guinea-pig prostate gland. The effects of tamsulosin (0.1 and 0.3 nM) were investigated in adult and ageing male guinea pig prostate glands using conventional tension recording and electrophysiological intracellular microelectrode recording techniques. Tamsulosin reduced spontaneous activity, and had different age-dependent effects on adult and ageing guinea pigs at different concentrations. 0.1 nM tamsulosin caused a significantly greater reduction of spontaneous contractile and electrical activity in ageing guinea pigs in comparison to adult guinea pigs. In contrast, 0.3 nM tamsulosin had a significantly greater reduction of spontaneous contractile and electrical activity in adult guinea pigs in comparison to ageing guinea pigs. This study demonstrates that tamsulosin can modulate spontaneous myogenic stromal contractility and the underlying spontaneous electrical activity; tamsulosin does not block spontaneous activity. This reduction in spontaneous activity suggests that downstream cellular mechanisms underlying smooth muscle tone are being targeted, and these may represent novel therapeutic targets to better treat benign prostatic hyperplasia. © 2014 Wiley Periodicals, Inc.

  9. Large-scale transcriptome data reveals transcriptional activity of fission yeast LTR retrotransposons

    DEFF Research Database (Denmark)

    Mourier, Tobias; Willerslev, Eske

    2010-01-01

    makes it difficult to assess which elements are transcriptionally active, but data strongly indicates that only a subset of the LTR retrotransposons contribute significantly to the detected transcription. A considerable level of reverse strand transcription is also detected. Equal levels......BACKGROUND: Retrotransposons are transposable elements that proliferate within eukaryotic genomes through a process involving reverse transcription. The numbers of retrotransposons within genomes and differences between closely related species may yield insight into the evolutionary history......-requisite for retrotransposition is transcription of the elements. Given their intrinsic sequence redundancy, transcriptome-level analyses of transposable elements are scarce. We have used recently published transcriptome data from the fission yeast Schizosaccharomyces pombe to assess the ability to detect and describe...

  10. Spontaneous physical activity protects against fat mass gain.

    Science.gov (United States)

    Teske, J A; Billington, C J; Kuskowski, M A; Kotz, C M

    2012-04-01

    It is unclear whether elevated spontaneous physical activity (SPA, very low-intensity physical activity) positively influences body composition long term. We determined whether SPA and caloric intake were differentially related to the growth curve trajectories of body weight, fat mass (FM) and fat-free mass (FFM) between obesity resistant and Sprague-Dawley rats at specific age intervals. Body composition, SPA and caloric intake were measured in selectively-bred obesity-resistant and out-bred Sprague-Dawley rats from 1 to 18 months. Data from development throughout maturation were analyzed by longitudinal growth curve modeling to determine the rate and acceleration of body weight, FM- and FFM-gain. Obesity-resistant rats had a lower rate of FM gain overall, a lower acceleration in body weight early in life, significantly greater SPA and lower cumulative caloric intake. Greater SPA in obesity-resistant rats was significantly associated with a lower rate of FM gain overall and lower acceleration in body weight early in life. Obesity resistant rats lost less FFM compared with Sprague-Dawley rats despite that obesity-resistant rats had a lower acceleration in FFM gain early in life. Obesity-resistant rats gained less FM and more FFM per gram body weight and were less energy efficient than Sprague-Dawley rats. Caloric intake was significantly and positively related to body weight, FM and FFM gain in both groups. Circadian patterns of caloric intake were group and age-dependent. Our data demonstrate that elevated and sustained SPA during development and over the lifespan are related to the reduced the rate of FM gain and may preserve FFM. These data support the idea that SPA level is a reproducible marker that reliably predicts propensity for obesity in rats, and that elevated levels of SPA maintained during the lifespan promote a lean phenotype.

  11. Noise-induced effects on multicellular biopacemaker spontaneous activity: Differences between weak and strong pacemaker cells

    Science.gov (United States)

    Aghighi, Alireza; Comtois, Philippe

    2017-09-01

    Self-organization of spontaneous activity of a network of active elements is important to the general theory of reaction-diffusion systems as well as for pacemaking activity to initiate beating of the heart. Monolayer cultures of neonatal rat ventricular myocytes, consisting of resting and pacemaker cells, exhibit spontaneous activation of their electrical activity. Similarly, one proposed approach to the development of biopacemakers as an alternative to electronic pacemakers for cardiac therapy is based on heterogeneous cardiac cells with resting and spontaneously beating phenotypes. However, the combined effect of pacemaker characteristics, density, and spatial distribution of the pacemaker cells on spontaneous activity is unknown. Using a simple stochastic pattern formation algorithm, we previously showed a clear nonlinear dependency of spontaneous activity (occurrence and amplitude of spontaneous period) on the spatial patterns of pacemaker cells. In this study, we show that this behavior is dependent on the pacemaker cell characteristics, with weaker pacemaker cells requiring higher density and larger clusters to sustain multicellular activity. These multicellular structures also demonstrated an increased sensitivity to voltage noise that favored spontaneous activity at lower density while increasing temporal variation in the period of activity. This information will help researchers overcome the current limitations of biopacemakers.

  12. Spontaneous sigh rates during sedentary activity: watching television vs reading.

    Science.gov (United States)

    Hark, William T; Thompson, William M; McLaughlin, Timothy E; Wheatley, Lisa M; Platts-Mills, Thomas A E

    2005-02-01

    Spontaneous sighs are thought to play an important role in preventing atelectasis and in regulating airway tone. Recent studies have provided a mechanism by which expansion of the lungs could cause relaxation of smooth muscle. To investigate breathing patterns during 2 forms of sedentary behavior: reading and watching television. Breathing patterns were monitored for 1 to 2 hours to document respiratory rates and sigh rates. Each participant was monitored while reading and while watching a movie on videotape. During the first experiment (17 controls), metabolic rates were also measured. In the second experiment (18 controls and 9 patients with mild-to-moderate asthma), only breathing patterns were monitored. There were no significant differences in respiratory or metabolic rates between the 2 activities. In contrast, in the first experiment, 13 of 17 controls had lower sigh rates while watching a videotape than while reading (P < .01). In the second experiment, the sigh rate was significantly lower overall while watching a videotape (mean, 13.7 sighs per hour; range, 1.8-26.0 sighs per hour) than while reading (mean, 19.3 sighs per hour; range, 7.7-30.0 sighs per hour) (P < .001). A similar decrease was observed in patients with asthma (P < .01). Given that many children and adults watch television for 5 or more hours per day, breathing patterns during this time may be relevant to lung function. Our results demonstrate that prolonged periods of watching a videotape are associated with lower sigh rates than while reading. Further research is needed to determine whether these changes are relevant to increased bronchial reactivity.

  13. Investigation of the activation of the temporalis and masseter muscles in voluntary and spontaneous smile production.

    Science.gov (United States)

    Steele, Jessica E; Woodcock, Ian R; Murphy, Adrian D; Ryan, Monique M; Penington, Tony J; Coombs, Christopher J

    2018-03-06

    Masticatory muscles or their nerve supply are options for facial reanimation surgery, but their ability to create spontaneous smile has been questioned. This study assessed the percentage of healthy adults who activate the temporalis and masseter muscles during voluntary and spontaneous smile. Healthy volunteer adults underwent electromyography (EMG) studies of the temporalis and masseter muscles during voluntary and spontaneous smile. Responses were repeated three times and recorded as negative, weakly positive, or strongly positive according to the activity observed. The best response was used for analysis. Thirty healthy adults (median age: 34 years, range: 25-69 years) participated. Overall, 92% of the masseter muscles were activated during voluntary smile (22% strong, 70% weak). Seventy-seven percent of the masseter muscles were activated in spontaneous smile (12% strong, 65% weak). The temporalis muscle was activated in 62% of responses in voluntary smile (15% strong, 47% weak) and in 45% of responses in spontaneous smile (13% strong, 32% weak). No significant difference was found for males vs females or closed vs open mouth smiles. There was no significant difference in responses between voluntary and spontaneous smiles for the temporalis and masseter muscles, and their use in voluntary smile did not predict activity in spontaneous smile. Our study has shown that masseter and temporalis are active in a high proportion of healthy adults during voluntary and spontaneous smiles. Further work is required to determine the relationship between preoperative donor muscle activation and postoperative spontaneous smile, and whether masticatory muscle activity can be upregulated with appropriate training. Copyright © 2018. Published by Elsevier Ltd.

  14. Spontaneous activity in the developing mammalian retina: Form and function

    Science.gov (United States)

    Butts, Daniel Allison

    Spontaneous neuronal activity is present in the immature mammalian retina during the initial stages of visual system development, before the retina is responsive to light. This activity consists of bursts of action potentials fired by retinal ganglion cells, and propagates in a wavelike manner across the inner plexiform layer of the retina. Unlike waves in other neural systems, retinal waves have large variability in both their rate and direction of propagation, and individual waves only propagate across small regions of the retina. The unique properties of retinal activity arise from dynamic processes within the developing retina, and produce characteristic spatiotemporal properties. These spatiotemporal properties are of particular interest, since they are believed to play a role in visual system development. This dissertation addresses the complex spatiotemporal patterning of the retinal waves from two different perspectives. First, it proposes how the immature circuitry of the developing retina generates these patterns of activity. In order to reproduce the distinct spatiotemporal properties observed in experiments, a model of the immature retinal circuitry must meet certain requirements, which are satisfied by a coarse-grained model of the developing retina that we propose. Second, this dissertation addresses how the particular spatiotemporal patterning of the retinal waves provides information to the rest of the visual system and, as a result, can be used to guide visual system development. By measuring the properties of this information, we place constraints on the developmental mechanisms that use this activity, and show how the particular spatiotemporal properties of the retinal waves provide this information. Together, this dissertation demonstrates how the apparent complexity of retinal wave patterning can be understood both through the immature circuitry that generates it, and through the developmental mechanisms that may use it. The first three

  15. Regulation of fission yeast morphogenesis by PP2A activator pta2.

    Directory of Open Access Journals (Sweden)

    Manuel Bernal

    Full Text Available Cell polarization is key for the function of most eukaryotic cells, and regulates cell shape, migration and tissue architecture. Fission yeast, Schizosaccharomyces pombe cells are cylindrical and polarize cell growth to one or both cell tips dependent on the cell cycle stage. Whereas microtubule cytoskeleton contributes to the positioning of the growth sites by delivering polarity factors to the cell ends, the Cdc42 GTPase polarizes secretion via actin-dependent delivery and tethering of secretory vesicles to plasma membrane. How growth is restricted to cell tips and how re-initiation of tip growth is regulated in the cell cycle remains poorly understood. In this work we investigated the function of protein phosphatase type 2A (PP2A in S. pombe morphogenesis by deleting the evolutionary conserved PTPA-type regulatory subunit that we named pta2. pta2-deleted cells showed morphological defects and altered growth pattern. Consistent with this, actin patches and active Cdc42 were mislocalized in the pta2 deletion. These defects were additive to the lack of Cdc42-GAP Rga4. pta2Δ cells show upregulated Cdc42 activity and pta2 interacts genetically with polarisome components Tea1, Tea4 and For3 leading to complete loss of cell polarity and rounded morphology. Thus, regulation of polarity by PP2A requires the polarisome and involves Pta2-dependent control of Cdc42 activity.

  16. 5He, 7He and 8Li (E=2.26 MeV) intermediate ternary particles in the spontaneous fission of 252Cf

    International Nuclear Information System (INIS)

    Kopatch, Yu. N.; Goennenwein, F.

    2002-02-01

    The neutron-unstable odd-N isotopes 5 He, 7 He and 8 Li (in its excited state of E * = 2.26 MeV) were measured to show up as short-lived intermediate light-charged-particles (LCP) in ternary fission of 252 Cf. For the study a high-efficiency angular correlation measurement between neutrons, LCPs and main fission fragments has been performed. The evidence for the ternary 5 He and 7 He particles (lifetimes: 1 x 10 -21 s, and 4 x 10 -21 s, respectively) was disclosed from the measured angular distributions of their decay neutrons focused by the emission in flight towards the direction of motion of 4 He and 6 He ternary particles. Similarly, neutrons observed to be peaked around Li-particle motion could be attributed to the decay of the second excited state at E * = 2.26 MeV (lifetime: 2 x 10 -20 s) of 8 Li. The fractional yields of the intermediate 5 He and 7 He ternary fission modes relative to the ''true'' ternary 4 He and 6 He modes, respectively, were determined to be 0.21(5) for both cases. The mean energy of the 4 He residues resulting from the 5 He decay was determined to be 12.4(3) MeV, compared to 15.7(2) MeV for all ternary α-particles registered, and to 16.4(3) MeV for the true ternary α-particles. The mean energy of the 6 He residues from the 7 He decay is 11.0(15) MeV, compared to 12.3(5) MeV for all ternary 6 He particles. The population of 8 Li * was deduced to be 0.06(2) relative to Li ternary fission, and 0.33(20) relative to the yield of particle stable 8 Li. The perspective of using the observed intermediate LCPs for probing the ternary scission configuration in 252 Cf fission with the aid of trajectory calculations is briefly discussed. (orig.)

  17. The nuclear fission process

    International Nuclear Information System (INIS)

    Wagemans, C.

    1991-01-01

    Fifty years after its discovery, the nuclear fission phenomenon is of recurring interest. When its fundamental physics aspects are considered, fission is viewed in a very positive way, which is reflected in the great interest generated by the meetings and large conferences organized for the 50th anniversary of its discovery. From a purely scientific and practical point of view, a new book devoted to the (low energy) nuclear fission phenomenon was highly desirable considering the tremendous amount of new results obtained since the publication of the book Nuclear Fission by Vandenbosch and Huizenga in 1973 (Academic Press). These new results could be obtained thanks to the growth of technology, which enabled the construction of powerful new neutron sources, particle and heavy ion accelerators, and very performant data-acquisition and computer systems. The re-invention of the ionization chamber, the development of large fission fragment spectrometers and sophisticated multiparameter devices, and the production of exotic isotopes also contributed significantly to an improved understanding of nuclear fission. This book is written at a level to introduce graduate students to the exciting subject of nuclear fission. The very complete list of references following each chapter also makes the book very useful for scientists, especially nuclear physicists. The book has 12 chapters covering the fission barrier and the various processes leading to fission as well as the characteristics of the various fission reaction products. In order to guarantee adequate treatment of the very specialized research fields covered, several distinguished scientists actively involved in some of these fields were invited to contribute their expertise as authors or co-authors of the different chapters

  18. DELTAMETHRIN AND PERMETHRIN DECREASE SPONTANEOUS ACTIVITY IN NEURONAL NETWORKS IN VITRO.

    Science.gov (United States)

    Effects of pyrethroid insecticides on spontaneous electrical activity were investigated in primary cultures of cortical or spinal cord neurons grown on microelectrode arrays. Bicuculline (40 ¿M) was utilized to block fast GABAergic transmission, and concentration-dependent effect...

  19. LOFC fission product release and circulating activity calculations for gas-cooled reactors

    International Nuclear Information System (INIS)

    Apperson, C.E. Jr.; Carruthers, L.M.; Lee, C.E.

    1977-01-01

    The inventories of fission products in a gas-cooled reactor under accident and normal steady state conditions are time and temperature dependent. To obtain a reasonable estimate of these inventories it is necessary to consider fuel failure, a temperature dependent variable, and radioactive decay, a time dependent variable. Using arbitrary radioactive decay chains and published fuel failure models for the High Temperature Gas-Cooled Reactor (HTGR), methods have been developed to evaluate the release of fission products during the Loss of Forced Circulation (LOFC) accident and the circulating and plateout fission product inventories during steady state non-accident operation. The LARC-2 model presented here neglects the time delays in the release from the HTGR due to diffusion of fission products from particles in the fuel rod through the graphite matrix. It also neglects the adsorption and evaporation process of metallics at the fuel rod-graphite and graphite-coolant hole interfaces. Any time delay due to the finite time of transport of fission products by convection through the coolant to the outside of the prestressed concrete reactor vessel (PCRV) is also neglected. This model assumes that all fission products released from fuel particles are immediately deposited outside the PCRV with no time delay

  20. The Neural Association between Tendency to Forgive and Spontaneous Brain Activity in Healthy Young Adults

    OpenAIRE

    Haijiang Li; Jiamei Lu

    2017-01-01

    The tendency to forgive (TTF) refers to one’s global dispositional level of forgiveness across situations and relationships. Previous brain imaging studies examined activation patterns underlying forgiving process, yet the association between individual differences in the TTF and spontaneous brain activity at resting-state remains unknown. In this study, resting-state functional magnetic resonance imaging (fMRI) was used to investigate the correlation between the TTF and spontaneous brain act...

  1. Endosulfan induces changes in spontaneous swimming activity and acetylcholinesterase activity of Jenynsia multidentata (Anablepidae, Cyprinodontiformes)

    Energy Technology Data Exchange (ETDEWEB)

    Ballesteros, M.L. [Facultad de Ciencias Exactas, Fisicas y Naturales, Catedra Diversidad Animal II, Universidad Nacional de Cordoba, Av. Velez Sarsfield 299, 5000 Cordoba (Argentina); Durando, P.E. [Facultad de Ciencias Exactas, Fisicas y Naturales, Departamento de Biologia, Catedra de Fisiologia Animal, Universidad Nacional de San Juan, Complejo ' Islas Malvinas' , Av. Jose I. de la Roza y Meglioli, Rivadavia, San Juan (Argentina); Nores, M.L. [Facultad de Ciencias Medicas, Universidad Nacional de Cordoba-CONICET, Ciudad Universitaria, Cordoba (Argentina); Diaz, M.P. [Facultad de Ciencias Medicas, Catedra de Estadistica y Bioestadistica, Escuela de Nutricion, Universidad Nacional de Cordoba, Pabellon Chile, Ciudad Universitaria, 5000 Cordoba (Argentina); Bistoni, M.A., E-mail: mbistoni@com.uncor.ed [Facultad de Ciencias Exactas, Fisicas y Naturales, Catedra Diversidad Animal II, Universidad Nacional de Cordoba, Av. Velez Sarsfield 299, 5000 Cordoba (Argentina); Wunderlin, D.A. [Facultad de Ciencias Quimicas, Dto. Bioquimica Clinica-CIBICI, Universidad Nacional de Cordoba-CONICET, Haya de la Torre esq. Medina Allende, Ciudad Universitaria, 5000 Cordoba (Argentina)

    2009-05-15

    We assessed changes in spontaneous swimming activity and acetylcholinesterase (AchE) activity of Jenynsia multidentata exposed to Endosulfan (EDS). Females of J. multidentata were exposed to 0.072 and 1.4 mug L{sup -1} EDS. Average speed and movement percentage were recorded during 48 h. We also exposed females to EDS at five concentrations between 0.072 and 1.4 mug L{sup -1} during 24 h, and measured the AchE activity in brain and muscle. At 0.072 mug L{sup -1} EDS swimming motility decreased relative to the control group after 45 h, while at 1.4 mug L{sup -1} EDS swimming motility decreased after 24 h. AchE activity significantly decreased in muscle when J. multidentata were exposed to EDS above 0.072 mug L{sup -1}, while no significant changes were observed in brain. Thus, changes in swimming activity and AchE activity in muscle are good biomarkers of exposure to EDS in J. multidentata. - This work reports changes observed in spontaneous swimming activity and AchE activity of Jenynsia multidentata exposed to sublethal concentrations of Endosulfan.

  2. Endosulfan induces changes in spontaneous swimming activity and acetylcholinesterase activity of Jenynsia multidentata (Anablepidae, Cyprinodontiformes)

    International Nuclear Information System (INIS)

    Ballesteros, M.L.; Durando, P.E.; Nores, M.L.; Diaz, M.P.; Bistoni, M.A.; Wunderlin, D.A.

    2009-01-01

    We assessed changes in spontaneous swimming activity and acetylcholinesterase (AchE) activity of Jenynsia multidentata exposed to Endosulfan (EDS). Females of J. multidentata were exposed to 0.072 and 1.4 μg L -1 EDS. Average speed and movement percentage were recorded during 48 h. We also exposed females to EDS at five concentrations between 0.072 and 1.4 μg L -1 during 24 h, and measured the AchE activity in brain and muscle. At 0.072 μg L -1 EDS swimming motility decreased relative to the control group after 45 h, while at 1.4 μg L -1 EDS swimming motility decreased after 24 h. AchE activity significantly decreased in muscle when J. multidentata were exposed to EDS above 0.072 μg L -1 , while no significant changes were observed in brain. Thus, changes in swimming activity and AchE activity in muscle are good biomarkers of exposure to EDS in J. multidentata. - This work reports changes observed in spontaneous swimming activity and AchE activity of Jenynsia multidentata exposed to sublethal concentrations of Endosulfan.

  3. Patchwork-Type Spontaneous Activity in Neonatal Barrel Cortex Layer 4 Transmitted via Thalamocortical Projections

    Directory of Open Access Journals (Sweden)

    Hidenobu Mizuno

    2018-01-01

    Full Text Available Summary: Establishment of precise neuronal connectivity in the neocortex relies on activity-dependent circuit reorganization during postnatal development; however, the nature of cortical activity during this period remains largely unknown. Using two-photon calcium imaging of the barrel cortex in vivo during the first postnatal week, we reveal that layer 4 (L4 neurons within the same barrel fire synchronously in the absence of peripheral stimulation, creating a “patchwork” pattern of spontaneous activity corresponding to the barrel map. By generating transgenic mice expressing GCaMP6s in thalamocortical axons, we show that thalamocortical axons also demonstrate the spontaneous patchwork activity pattern. Patchwork activity is diminished by peripheral anesthesia but is mostly independent of self-generated whisker movements. The patchwork activity pattern largely disappeared during postnatal week 2, as even L4 neurons within the same barrel tended to fire asynchronously. This spontaneous L4 activity pattern has features suitable for thalamocortical (TC circuit refinement in the neonatal barrel cortex. : By two-photon calcium imaging of layer 4 neurons and thalamocortical axon terminals in neonatal mouse barrel cortex, Mizuno et al. find a patchwork-like spontaneous activity pattern corresponding to the barrel map, which may be important for thalamocortical circuit maturation. Keywords: activity-dependent development, spontaneous activity, synchronized activity, barrel cortex, thalamocortical axons, neonates, in vivo calcium imaging, awake, single-cell labeling, whisker monitoring

  4. Direct Ring Fission of Salicylate by a Salicylate 1,2-Dioxygenase Activity from Pseudaminobacter salicylatoxidans

    Science.gov (United States)

    Hintner, Jan-Peter; Lechner, Christa; Riegert, Ulrich; Kuhm, Andrea Elisabeth; Storm, Thomas; Reemtsma, Thorsten; Stolz, Andreas

    2001-01-01

    In cell extracts of Pseudaminobacter salicylatoxidans strain BN12, an enzymatic activity was detected which converted salicylate in an oxygen-dependent but NAD(P)H-independent reaction to a product with an absorbance maximum at 283 nm. This metabolite was isolated, purified, and identified by mass spectrometry and 1H and 13C nuclear magnetic resonance spectroscopy as 2-oxohepta-3,5-dienedioic acid. This metabolite could be formed only by direct ring fission of salicylate by a 1,2-dioxygenase reaction. Cell extracts from P. salicylatoxidans also oxidized 5-aminosalicylate, 3-, 4-, and 5-chlorosalicylate, 3-, 4-, and 5-methylsalicylate, 3- and 5-hydroxysalicylate (gentisate), and 1-hydroxy-2-naphthoate. The dioxygenase was purified and shown to consist of four identical subunits with a molecular weight of about 45,000. The purified enzyme showed higher catalytic constants with gentisate or 1-hydroxy-2-naphthoate than with salicylate. It was therefore concluded that P. salicylatoxidans synthesized a gentisate 1,2-dioxygenase with an extraordinary substrate range, which also allowed the oxidation of salicylate. PMID:11698383

  5. Constitutive Activation of the Fission Yeast Pheromone-Responsive Pathway Induces Ectopic Meiosis and Reveals Ste11 as a Mitogen-Activated Protein Kinase Target

    DEFF Research Database (Denmark)

    Kjærulff, Søren; Lautrup-Larsen, I.; Truelsen, S.

    2005-01-01

    In the fission yeast Schizosaccharomyces pombe, meiosis normally takes place in diploid zygotes resulting from conjugation of haploid cells. In the present study, we report that the expression of a constitutively activated version of the pheromone-responsive mitogen-activated protein kinase kinase...

  6. Fission - track age of the Marjalahti Pallasite

    International Nuclear Information System (INIS)

    Bondar, Yu.V.; Perelygin, V.P.

    2006-01-01

    Full text: Investigation of fossil charged-particle tracks in various mineral phases of extraterrestrial samples is a powerful method for research the early stages of the solar system. Over geological time, meteorites crystals have accumulated a record of tracks produced by heavily charged energetic particles from both internal (spontaneous fission of 238U and some other extinct isotopes) and external sources (galactic cosmic rays with Z>20). The fortunate fact that meteorite grains can accumulate latent and very long-lived tracks since soon after the end of nucleosynthesis in the solar nebula enables one to decode their radiation history and to detect any thermal events in the meteorite cosmic history by revealing these tracks through suitable etching procedures. Only a few minerals in meteorites (mainly phosphates) contain small amount of uranium; the fact that 238 U undergoes fission with fission-decay constant λ f ∼ 8.2x10 -17 yr -1 allows one to use this isotope as a chronometer. By measuring the U concentration in the crystals (by reactor irradiation) and the density of the spontaneous-fission tracks it is relatively easy to calculate the 'fission-track age' if 238 U is the main source of fission tracks. However the fission-track dating of extraterrestrial samples compared with the terrestrial ones has some peculiar features due to presence of a number of other potential track sources except the spontaneous fission of 238 U, such as the spontaneous fission of presently extinct 244 Pu, heavy nuclei of cosmic rays and induced fission by cosmic ray primaries. Only tracks from the spontaneous fission of U and Pu are suitable for fission-track dating. The competing effects of these fissioning elements, whose half-lives differ by a factor of ∼50, form a basis for a fission-track chronology for samples older than ∼ 4.0 Gyr. Over small intervals in time (∼ few x10 8 yr ) the track density from spontaneous fission of 238 U is nearly constant. However, the

  7. Ongoing spontaneous activity controls access to consciousness: a neuronal model for inattentional blindness.

    Directory of Open Access Journals (Sweden)

    Stanislas Dehaene

    2005-05-01

    Full Text Available Even in the absence of sensory inputs, cortical and thalamic neurons can show structured patterns of ongoing spontaneous activity, whose origins and functional significance are not well understood. We use computer simulations to explore the conditions under which spontaneous activity emerges from a simplified model of multiple interconnected thalamocortical columns linked by long-range, top-down excitatory axons, and to examine its interactions with stimulus-induced activation. Simulations help characterize two main states of activity. First, spontaneous gamma-band oscillations emerge at a precise threshold controlled by ascending neuromodulator systems. Second, within a spontaneously active network, we observe the sudden "ignition" of one out of many possible coherent states of high-level activity amidst cortical neurons with long-distance projections. During such an ignited state, spontaneous activity can block external sensory processing. We relate those properties to experimental observations on the neural bases of endogenous states of consciousness, and particularly the blocking of access to consciousness that occurs in the psychophysical phenomenon of "inattentional blindness," in which normal subjects intensely engaged in mental activity fail to notice salient but irrelevant sensory stimuli. Although highly simplified, the generic properties of a minimal network may help clarify some of the basic cerebral phenomena underlying the autonomy of consciousness.

  8. Ongoing spontaneous activity controls access to consciousness: a neuronal model for inattentional blindness.

    Science.gov (United States)

    Dehaene, Stanislas; Changeux, Jean-Pierre

    2005-05-01

    Even in the absence of sensory inputs, cortical and thalamic neurons can show structured patterns of ongoing spontaneous activity, whose origins and functional significance are not well understood. We use computer simulations to explore the conditions under which spontaneous activity emerges from a simplified model of multiple interconnected thalamocortical columns linked by long-range, top-down excitatory axons, and to examine its interactions with stimulus-induced activation. Simulations help characterize two main states of activity. First, spontaneous gamma-band oscillations emerge at a precise threshold controlled by ascending neuromodulator systems. Second, within a spontaneously active network, we observe the sudden "ignition" of one out of many possible coherent states of high-level activity amidst cortical neurons with long-distance projections. During such an ignited state, spontaneous activity can block external sensory processing. We relate those properties to experimental observations on the neural bases of endogenous states of consciousness, and particularly the blocking of access to consciousness that occurs in the psychophysical phenomenon of "inattentional blindness," in which normal subjects intensely engaged in mental activity fail to notice salient but irrelevant sensory stimuli. Although highly simplified, the generic properties of a minimal network may help clarify some of the basic cerebral phenomena underlying the autonomy of consciousness.

  9. Gamma-ray multiplicity measurement of the spontaneous fission decay of 252Cf in a segmented HPGe/BGO detector array

    Energy Technology Data Exchange (ETDEWEB)

    Bleuel, D L; Bernstein, L A; Burke, J T; Gibelin, J; Heffner, M D; Mintz, J; Norman, E B; Phair, L; Scielzo, N D; Sheets, S A; Snyderman, N J; Stoyer, M A; Wiedeking, M

    2008-04-23

    Coincident {gamma} rays from a {sup 252}Cf source were measured using an array of six segmented high-purity germanium (HPGe) Clover detectors each enclosed by 16 bismuth-germanate (BGO) detectors. The detectors were arranged in a cubic pattern around a 1 {micro}Ci {sup 252}Cf source to cover a large solid angle for {gamma}-ray measurement with a reasonable reconstruction of the multiplicity. Neutron multiplicity was determined in certain cases by identifying the prompt {gamma} rays from individual fission fragment pairs. Multiplicity distributions from previous experiments and theoretical models were convolved with the response function of the array and compared to the present results. These results suggest a {gamma}-ray multiplicity spectrum broader than previous measurements and models, and provide no evidence of correlation with neutron multiplicity.

  10. Compilation of Data on Radionuclide Data for Specific Activity, Specific Heat and Fission Product Yields

    Energy Technology Data Exchange (ETDEWEB)

    Gibbs, A.; Thomason, R.S.

    2000-09-05

    This compilation was undertaken to update the data used in calculation of curie and heat loadings of waste containers in the Solid Waste Management Facility. The data has broad general use and has been cross-checked extensively in order to be of use in the Materials Accountability arena. The fission product cross-sections have been included because they are of use in the Environmental Remediation and Waste Management areas where radionuclides which are not readily detectable need to be calculated from the relative fission yields and material dispersion data.

  11. Theoretical Description of the Fission Process

    Energy Technology Data Exchange (ETDEWEB)

    Witold Nazarewicz

    2003-07-01

    The main goals of the project can be summarized as follows: Development of effective energy functionals that are appropriate for the description of heavy nuclei. Our goal is to improve the existing energy density (Skyrme) functionals to develop a force that will be used in calculations of fission dynamics. Systematic self-consistent calculations of binding energies and fission barriers of actinide and trans-actinide nuclei using modern density functionals. This will be followed by calculations of spontaneous fission lifetimes and mass and charge divisions using dynamic adiabatic approaches based on the WKB approximation. Investigate novel microscopic (non-adiabatic) methods to study the fission process.

  12. Theoretical Description of the Fission Process

    International Nuclear Information System (INIS)

    Witold Nazarewicz

    2003-01-01

    The main goals of the project can be summarized as follows: Development of effective energy functionals that are appropriate for the description of heavy nuclei. Our goal is to improve the existing energy density (Skyrme) functionals to develop a force that will be used in calculations of fission dynamics. Systematic self-consistent calculations of binding energies and fission barriers of actinide and trans-actinide nuclei using modern density functionals. This will be followed by calculations of spontaneous fission lifetimes and mass and charge divisions using dynamic adiabatic approaches based on the WKB approximation. Investigate novel microscopic (non-adiabatic) methods to study the fission process

  13. Spontaneous Neuronal Activity in Developing Neocortical Networks: From Single Cells to Large-Scale Interactions.

    Science.gov (United States)

    Luhmann, Heiko J; Sinning, Anne; Yang, Jenq-Wei; Reyes-Puerta, Vicente; Stüttgen, Maik C; Kirischuk, Sergei; Kilb, Werner

    2016-01-01

    Neuronal activity has been shown to be essential for the proper formation of neuronal circuits, affecting developmental processes like neurogenesis, migration, programmed cell death, cellular differentiation, formation of local and long-range axonal connections, synaptic plasticity or myelination. Accordingly, neocortical areas reveal distinct spontaneous and sensory-driven neuronal activity patterns already at early phases of development. At embryonic stages, when immature neurons start to develop voltage-dependent channels, spontaneous activity is highly synchronized within small neuronal networks and governed by electrical synaptic transmission. Subsequently, spontaneous activity patterns become more complex, involve larger networks and propagate over several neocortical areas. The developmental shift from local to large-scale network activity is accompanied by a gradual shift from electrical to chemical synaptic transmission with an initial excitatory action of chloride-gated channels activated by GABA, glycine and taurine. Transient neuronal populations in the subplate (SP) support temporary circuits that play an important role in tuning early neocortical activity and the formation of mature neuronal networks. Thus, early spontaneous activity patterns control the formation of developing networks in sensory cortices, and disturbances of these activity patterns may lead to long-lasting neuronal deficits.

  14. Effects of Amoxicillin and Clavulanic Acid on the Spontaneous Mechanical Activity of Juvenile Rat Duodenum.

    Science.gov (United States)

    Ciciora, Steven L; Williams, Kent C; Gariepy, Cheryl E

    2015-09-01

    There are a limited number of medications for the treatment of foregut dysmotility. Enteral amoxicillin/clavulanic acid induces phase III duodenal contractions in a fasting pediatric patient. The mechanism by which this occurs is unknown. We examined the individual contributions of amoxicillin and clavulanic acid on the spontaneous mechanical activity of juvenile rat duodenum to better understand this phenomenon. Duodenal segments from juvenile rats were longitudinally attached to force transducers in organ baths. Samples were cumulatively exposed to amoxicillin or clavulanic acid. Separate samples were exposed to carbachol alone to assess response in both the presence and absence of amoxicillin or clavulanic acid. Basal tone, frequency, and amplitude of contractions were digitized and recorded. The amplitude of the spontaneous contractions increased with amoxicillin. Inhibition of neuronal activity prevented this effect. Clavulanic acid did not affect the spontaneous contractions. Basal tone and the rate of contractions did not differ with either drug. Stimulation with carbachol in the presence of amoxicillin caused a statistically significant increase in the contractility compared with carbachol alone. Amoxicillin alters the spontaneous longitudinal mechanical activity of juvenile rat duodenum. Our results suggest that amoxicillin modulates the spontaneous pattern of cyclic mechanical activity of duodenal smooth muscle through noncholinergic, neurally mediated mechanisms. Our work provides an initial physiologic basis for the therapeutic use of amoxicillin in patients with gastrointestinal dysmotility.

  15. The effects of tricyclic and 'atypical' antidepressants on spontaneous locomotor activity in rodents.

    Science.gov (United States)

    Tucker, J C; File, S E

    1986-01-01

    With the exception of amineptin, buproprion and nomifensine all tricyclic and 'atypical' antidepressants have been reported to reduce spontaneous motor activity in rodents, after both acute and chronic administration. However, with the diversity of chemical actions of these drugs it is unlikely that a single neurochemical mechanism is underlying this one behavioral effect. These widespread sedative effects have implications for interpreting behavioral changes in other test situations, since sedation generally occurs at doses that fall within the dose-range effective in other tests. We also review the effects on spontaneous motor activity of withdrawal from chronic antidepressant treatment.

  16. Changes of spontaneous parthenogenetic activation and development potential of golden hamster oocytes during the aging process.

    Science.gov (United States)

    Jiang, Han; Wang, Ce; Guan, Jiyu; Wang, Lingyan; Li, Ziyi

    2015-01-01

    The golden hamster is an excellent animal experimental model for oocyte research. The hamster oocytes are very useful in clinical examination of human spermatozoan activity. Non-fertile oocytes can lead to time-dependent processes of aging, which will affect the results of human spermatozoa examination. As a consequence there is a need to investigate the aging and anti-aging processes of golden hamster oocytes. In order to study the aging processes and parthenogenetic activation of golden hamster oocytes, in vivo oocytes, oocytes cultured with or without cumulus cells, and oocytes treated with Trichostatin A (TSA) or caffeine were collected and investigated. We found that: (1) spontaneous parthenogenetic activation, developmental potential (cleavage rate), and zona pellucida (ZP) hardening undergo age-dependent changes in in vivo, in vitro, and after TSA or caffeine treatment; (2) in vivo, oocytes became spontaneously parthenogenetic 25 h post-hCG treatment; (3) in vitro, cumulus cells did not significantly increase the parthenogenetic activation rate of cultured hamster oocytes; and (4) TSA or caffeine could delay spontaneous oocyte parthenogenetic activation and the aging processes by at least 5h, but also accelerated the hardening of the ZP. These results define the conditions for the aging and anti-aging processes in golden hamster oocytes. TSA and caffeine play roles in controlling spontaneous activation, which could facilitate the storage and use of golden hamster oocytes for studying processes relevant to human reproduction. Copyright © 2014 Elsevier GmbH. All rights reserved.

  17. Measurement of 235U fission spectrum-averaged cross sections and neutron spectrum adjusted with the activation data

    International Nuclear Information System (INIS)

    Kobayashi, Katsuhei; Kobayashi, Tooru

    1992-01-01

    The 235 U fission spectrum-averaged cross sections for 13 threshold reactions were measured with the fission plate (27 cm in diameter and 1.1 cm thick) at the heavy water thermal neutron facility of the Kyoto University Reactor. The Monte Carlo code MCNP was applied to check the deviation from the 235 U fission neutron spectrum due to the room-scattered neutrons, and it was found that the resultant spectrum was close to that of 235 U fission neutrons. Supplementally, the relations to derive the absorbed dose rates with the fission plate were also given using the calculated neutron spectra and the neutron Kerma factors. Finally, the present values of the fission spectrum-averaged cross sections were employed to adjust the 235 U fission neutron spectrum with the NEUPAC code. The adjusted spectrum showed a good agreement with the Watt-type fission neutron spectrum. (author)

  18. Contribution to the study of nuclear fission

    International Nuclear Information System (INIS)

    Serot, O.

    2009-09-01

    The author proposes an overview of his research activity during the past fifteen years and more particularly that dealing with nuclear fission. The first part reports works on nucleus physics at the scission via the investigation of ternary fission (experimental procedure, influence of fission modes, influence of resonance spin, influence of excitation energy of the fissioning nucleus, emission probabilities, energy spectra of ternary alphas and tritons, emission mechanism). The second part reports measurements and assessments of neutron-induced fission cross sections. The third part reports the investigation of some properties of fission products (efficiencies, branching ratios of the main delayed neutron precursors)

  19. Recurrently connected and localized neuronal communities initiate coordinated spontaneous activity in neuronal networks.

    Science.gov (United States)

    Lonardoni, Davide; Amin, Hayder; Di Marco, Stefano; Maccione, Alessandro; Berdondini, Luca; Nieus, Thierry

    2017-07-01

    Developing neuronal systems intrinsically generate coordinated spontaneous activity that propagates by involving a large number of synchronously firing neurons. In vivo, waves of spikes transiently characterize the activity of developing brain circuits and are fundamental for activity-dependent circuit formation. In vitro, coordinated spontaneous spiking activity, or network bursts (NBs), interleaved within periods of asynchronous spikes emerge during the development of 2D and 3D neuronal cultures. Several studies have investigated this type of activity and its dynamics, but how a neuronal system generates these coordinated events remains unclear. Here, we investigate at a cellular level the generation of network bursts in spontaneously active neuronal cultures by exploiting high-resolution multielectrode array recordings and computational network modelling. Our analysis reveals that NBs are generated in specialized regions of the network (functional neuronal communities) that feature neuronal links with high cross-correlation peak values, sub-millisecond lags and that share very similar structural connectivity motifs providing recurrent interactions. We show that the particular properties of these local structures enable locally amplifying spontaneous asynchronous spikes and that this mechanism can lead to the initiation of NBs. Through the analysis of simulated and experimental data, we also show that AMPA currents drive the coordinated activity, while NMDA and GABA currents are only involved in shaping the dynamics of NBs. Overall, our results suggest that the presence of functional neuronal communities with recurrent local connections allows a neuronal system to generate spontaneous coordinated spiking activity events. As suggested by the rules used for implementing our computational model, such functional communities might naturally emerge during network development by following simple constraints on distance-based connectivity.

  20. Recurrently connected and localized neuronal communities initiate coordinated spontaneous activity in neuronal networks.

    Directory of Open Access Journals (Sweden)

    Davide Lonardoni

    2017-07-01

    Full Text Available Developing neuronal systems intrinsically generate coordinated spontaneous activity that propagates by involving a large number of synchronously firing neurons. In vivo, waves of spikes transiently characterize the activity of developing brain circuits and are fundamental for activity-dependent circuit formation. In vitro, coordinated spontaneous spiking activity, or network bursts (NBs, interleaved within periods of asynchronous spikes emerge during the development of 2D and 3D neuronal cultures. Several studies have investigated this type of activity and its dynamics, but how a neuronal system generates these coordinated events remains unclear. Here, we investigate at a cellular level the generation of network bursts in spontaneously active neuronal cultures by exploiting high-resolution multielectrode array recordings and computational network modelling. Our analysis reveals that NBs are generated in specialized regions of the network (functional neuronal communities that feature neuronal links with high cross-correlation peak values, sub-millisecond lags and that share very similar structural connectivity motifs providing recurrent interactions. We show that the particular properties of these local structures enable locally amplifying spontaneous asynchronous spikes and that this mechanism can lead to the initiation of NBs. Through the analysis of simulated and experimental data, we also show that AMPA currents drive the coordinated activity, while NMDA and GABA currents are only involved in shaping the dynamics of NBs. Overall, our results suggest that the presence of functional neuronal communities with recurrent local connections allows a neuronal system to generate spontaneous coordinated spiking activity events. As suggested by the rules used for implementing our computational model, such functional communities might naturally emerge during network development by following simple constraints on distance-based connectivity.

  1. A data repository and analysis framework for spontaneous neural activity recordings in developing retina.

    Science.gov (United States)

    Eglen, Stephen John; Weeks, Michael; Jessop, Mark; Simonotto, Jennifer; Jackson, Tom; Sernagor, Evelyne

    2014-03-26

    During early development, neural circuits fire spontaneously, generating activity episodes with complex spatiotemporal patterns. Recordings of spontaneous activity have been made in many parts of the nervous system over the last 25 years, reporting developmental changes in activity patterns and the effects of various genetic perturbations. We present a curated repository of multielectrode array recordings of spontaneous activity in developing mouse and ferret retina. The data have been annotated with minimal metadata and converted into HDF5. This paper describes the structure of the data, along with examples of reproducible research using these data files. We also demonstrate how these data can be analysed in the CARMEN workflow system. This article is written as a literate programming document; all programs and data described here are freely available. 1. We hope this repository will lead to novel analysis of spontaneous activity recorded in different laboratories. 2. We encourage published data to be added to the repository. 3. This repository serves as an example of how multielectrode array recordings can be stored for long-term reuse.

  2. The Role of Cellular Coupling in the Spontaneous Generation of Electrical Activity in Uterine Tissue

    Science.gov (United States)

    Xu, Jinshan; Menon, Shakti N.; Singh, Rajeev; Garnier, Nicolas B.; Sinha, Sitabhra; Pumir, Alain

    2015-01-01

    The spontaneous emergence of contraction-inducing electrical activity in the uterus at the beginning of labor remains poorly understood, partly due to the seemingly contradictory observation that isolated uterine cells are not spontaneously active. It is known, however, that the expression of gap junctions increases dramatically in the approach to parturition, by more than one order of magnitude, which results in a significant increase in inter-cellular electrical coupling. In this paper, we build upon previous studies of the activity of electrically excitable smooth muscle cells (myocytes) and investigate the mechanism through which the coupling of these cells to electrically passive cells results in the generation of spontaneous activity in the uterus. Using a recently developed, realistic model of uterine muscle cell dynamics, we investigate a system consisting of a myocyte coupled to passive cells. We then extend our analysis to a simple two-dimensional lattice model of the tissue, with each myocyte being coupled to its neighbors, as well as to a random number of passive cells. We observe that different dynamical regimes can be observed over a range of gap junction conductances: at low coupling strength, corresponding to values measured long before delivery, the activity is confined to cell clusters, while the activity for high coupling, compatible with values measured shortly before delivery, may spread across the entire tissue. Additionally, we find that the system supports the spontaneous generation of spiral wave activity. Our results are both qualitatively and quantitatively consistent with observations from in vitro experiments. In particular, we demonstrate that the increase in inter-cellular electrical coupling observed experimentally strongly facilitates the appearance of spontaneous action potentials that may eventually lead to parturition. PMID:25793276

  3. Putative role of border cells in generating spontaneous morphological activity within Kölliker's organ.

    Science.gov (United States)

    Dayaratne, M W Nishani; Vlajkovic, Srdjan M; Lipski, Janusz; Thorne, Peter R

    2015-12-01

    Kölliker's organ is a transient epithelial structure, comprising a major part of the organ of Corti during pre-hearing stages of development. The auditory system is spontaneously active during development, which serves to retain and refine neural connections. Kölliker's organ is considered a key candidate for generating such spontaneous activity, most likely through purinergic (P2 receptor) signalling and inner hair cell (IHC) activation. Associated with the spontaneous neural activity, ATP released locally by epithelial cells induces rhythmic morphological changes within Kölliker's organ, the purpose of which is not understood. These changes are accompanied by a shift in cellular refractive index, allowing optical detection of this activity in real-time. Using this principle, we investigated the origin of spontaneous morphological activity within Kölliker's organ. Apical turns of Wistar rat cochleae (P9-11) were dissected, and the purinergic involvement was studied following acute tissue exposure to a P2 receptor agonist (ATPγS) and antagonist (suramin). ATPγS induced a sustained darkening throughout Kölliker's organ, reversed by suramin. This effect was most pronounced in the region closest to the inner hair cells, which also displayed the highest frequency of intrinsic morphological events. Additionally, suramin alone induced swelling of this region, suggesting a tight regulation of cell volume by ATP-mediated mechanisms. Histological analysis of cochlear tissues demonstrates the most profound volume changes in the border cell region immediately adjacent to the IHCs. Together, these results underline the role of purinergic signalling in initiating morphological events within Kölliker's organ, and suggest a key involvement of border cells surrounding IHCs in regulating this spontaneous activity. Copyright © 2015. Published by Elsevier B.V.

  4. Effects of language processing on spontaneous muscle activity

    NARCIS (Netherlands)

    Stins, J.F.; Beek, P.J.

    2013-01-01

    There is evidence of the crucial involvement of the motor system in language understanding and production. We tested whether reading verbs that symbolized various actions would lead to an effector-specific modulation in subliminal muscle activity. Participants were lying in a relaxed position, and

  5. Changes of spontaneous oscillatory activity to tonic heat pain.

    Directory of Open Access Journals (Sweden)

    Weiwei Peng

    Full Text Available Transient painful stimuli could induce suppression of alpha oscillatory activities and enhancement of gamma oscillatory activities that also could be greatly modulated by attention. Here, we attempted to characterize changes in cortical activities during tonic heat pain perception and investigated the influence of directed/distracted attention on these responses. We collected 5-minute long continuous Electroencephalography (EEG data from 38 healthy volunteers during four conditions presented in a counterbalanced order: (A resting condition; (B innoxious-distracted condition; (C noxious-distracted condition; (D noxious-attended condition. The effects of tonic heat pain stimulation and selective attention on oscillatory activities were investigated by comparing the EEG power spectra among the four experimental conditions and assessing the relationship between spectral power difference and subjective pain intensity. The change of oscillatory activities in condition D was characterized by stable and persistent decrease of alpha oscillation power over contralateral-central electrodes and widespread increase of gamma oscillation power, which were even significantly correlated with subjective pain intensity. Since EEG responses in the alpha and gamma frequency band were affected by attention in different manners, they are likely related to different aspects of the multidimensional sensory experience of pain. The observed contralateral-central alpha suppression (conditions D vs. B and D vs. C may reflect primarily a top-down cognitive process such as attention, while the widespread gamma enhancement (conditions D vs. A may partly reflect tonic pain processing, representing the summary effects of bottom-up stimulus-related and top-down subject-driven cognitive processes.

  6. Effects of Organophosphorus Flame Retardants on Spontaneous Activity in Neuronal Networks Grown on Microelectrode Arrays

    Science.gov (United States)

    EFFECTS OF ORGANOPHOSPHORUS FLAME RETARDANTS ON SPONTANEOUS ACTIVITY IN NEURONAL NETWORKS GROWN ON MICROELECTRODE ARRAYS TJ Shafer1, K Wallace1, WR Mundy1, M Behl2,. 1Integrated Systems Toxicology Division, NHEERL, USEPA, RTP, NC, USA, 2National Toxicology Program, NIEHS, RTP, NC...

  7. DELTAMETHRIN AND ESFENVALERATE INHIBIT SPONTANEOUS NETWORK ACTIVITY IN RAT CORTICAL NEURONS IN VITRO.

    Science.gov (United States)

    Understanding pyrethroid actions on neuronal networks will help to establish a mode of action for these compounds, which is needed for cumulative risk decisions under the Food Quality Protection Act of 1996. However, pyrethroid effects on spontaneous activity in networks of inter...

  8. Slow-light enhancement of spontaneous emission in active photonic crystal waveguides

    DEFF Research Database (Denmark)

    Ek, Sara; Chen, Yaohui; Semenova, Elizaveta

    2012-01-01

    Photonic crystal defect waveguides with embedded active layers containing single or multiple quantum wells or quantum dots have been fabricated. Spontaneous emission spectra are enhanced close to the bandedge, consistently with the enhancement of gain by slow light effects. These are promising...

  9. Tinnitus perception and distress is related to abnormal spontaneous brain activity as measured by magnetoencephalography.

    Directory of Open Access Journals (Sweden)

    2005-06-01

    Full Text Available BACKGROUND: The neurophysiological mechanisms underlying tinnitus perception are not well understood. Surprisingly, there have been no group studies comparing abnormalities in ongoing, spontaneous neuronal activity in individuals with and without tinnitus perception. METHODS AND FINDINGS: Here, we show that the spontaneous neuronal activity of a group of individuals with tinnitus (n = 17 is characterised by a marked reduction in alpha (8-12 Hz power together with an enhancement in delta (1.5-4 Hz as compared to a normal hearing control group (n = 16. This pattern was especially pronounced for temporal regions. Moreover, correlations with tinnitus-related distress revealed strong associations with this abnormal spontaneous activity pattern, particularly in right temporal and left frontal areas. Overall, effects were stronger for the alpha than for the delta frequency band. A data stream of 5 min, recorded with a whole-head neuromagnetometer under a resting condition, was sufficient to extract the marked differences. CONCLUSIONS: Despite some limitations, there are arguments that the regional pattern of abnormal spontaneous activity we found could reflect a tinnitus-related cortical network. This finding, which suggests that a neurofeedback approach could reduce the adverse effects of this disturbing condition, could have important implications for the treatment of tinnitus.

  10. Altered Spontaneous Activity in Anisometropic Amblyopia Subjects: Revealed by Resting-State fMRI

    Science.gov (United States)

    Lin, Xiaoming; Ding, Kun; Liu, Yong; Yan, Xiaohe; Song, Shaojie; Jiang, Tianzi

    2012-01-01

    Amblyopia, also known as lazy eye, usually occurs during early childhood and results in poor or blurred vision. Recent neuroimaging studies have found cortical structural/functional abnormalities in amblyopia. However, until now, it was still not known whether the spontaneous activity of the brain changes in amblyopia subjects. In the present study, regional homogeneity (ReHo), a measure of the homogeneity of functional magnetic resonance imaging signals, was used for the first time to investigate changes in resting-state local spontaneous brain activity in individuals with anisometropic amblyopia. Compared with age- and gender-matched subjects with normal vision, the anisometropic amblyopia subjects showed decreased ReHo of spontaneous brain activity in the right precuneus, the left medial prefrontal cortex, the left inferior frontal gyrus, and the left cerebellum, and increased ReHo of spontaneous brain activity was found in the bilateral conjunction area of the postcentral and precentral gyri, the left paracentral lobule, the left superior temporal gyrus, the left fusiform gyrus, the conjunction area of the right insula, putamen and the right middle occipital gyrus. The observed decreases in ReHo may reflect decreased visuo-motor processing ability, and the increases in ReHo in the somatosensory cortices, the motor areas and the auditory area may indicate compensatory plasticity in amblyopia. PMID:22937041

  11. General theory for spontaneous emission in active dielectric microstructures: Example of a fiber amplifier

    DEFF Research Database (Denmark)

    Søndergaard, Thomas; Tromborg, Bjarne

    2001-01-01

    A model for spontaneous emission in active dielectric microstructures is given in terms of the classical electric field Green's tensor and the quantum-mechanical operators for the generating currents. A formalism is given for calculating the Green's tensor, which does not rely on the existence...

  12. Singlet Fission

    Czech Academy of Sciences Publication Activity Database

    Smith, M. B.; Michl, Josef

    2010-01-01

    Roč. 110, č. 11 (2010), s. 6891-6936 ISSN 0009-2665 Grant - others:Department of Energy(US) DE- FG36 -08GO18017 Institutional research plan: CEZ:AV0Z40550506 Keywords : solar energy conversion * photovoltaics * singlet fission Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 33.033, year: 2010

  13. Ternary fission

    Indian Academy of Sciences (India)

    2015-08-05

    Aug 5, 2015 ... We present the ternary fission of 252Cf and 236U within a three-cluster model as well as in a level density approach. The competition between collinear and equatorial geometry is studied by calculating the ternary fragmentation potential as a function of the angle between the lines joining the stationary ...

  14. Ternary fission

    Indian Academy of Sciences (India)

    the energy minimization of all possible ternary breakups of a heavy radioactive nucleus. Further, within the TCM we have analysed the competition between different geometries as well as different positioning of the fragments. Also, an attempt was made to calculate the mass distribution of ternary fission process within the ...

  15. Spontaneous Physical Activity Downregulates Pax7 in Cancer Cachexia

    Directory of Open Access Journals (Sweden)

    Dario Coletti

    2016-01-01

    Full Text Available Emerging evidence suggests that the muscle microenvironment plays a prominent role in cancer cachexia. We recently showed that NF-kB-induced Pax7 overexpression impairs the myogenic potential of muscle precursors in cachectic mice, suggesting that lowering Pax7 expression may be beneficial in cancer cachexia. We evaluated the muscle regenerative potential after acute injury in C26 colon carcinoma tumor-bearing mice and healthy controls. Our analyses confirmed that the delayed muscle regeneration observed in muscles form tumor-bearing mice was associated with a persistent local inflammation and Pax7 overexpression. Physical activity is known to exert positive effects on cachectic muscles. However, the mechanism by which a moderate voluntary exercise ameliorates muscle wasting is not fully elucidated. To verify if physical activity affects Pax7 expression, we hosted control and C26-bearing mice in wheel-equipped cages and we found that voluntary wheel running downregulated Pax7 expression in muscles from tumor-bearing mice. As expected, downregulation of Pax7 expression was associated with a rescue of muscle mass and fiber size. Our findings shed light on the molecular basis of the beneficial effect exerted by a moderate physical exercise on muscle stem cells in cancer cachexia. Furthermore, we propose voluntary exercise as a physiological tool to counteract the overexpression of Pax7 observed in cancer cachexia.

  16. Mass and Charge Distribution in Low-Energy Fission

    International Nuclear Information System (INIS)

    Wahl, A.C.

    1965-01-01

    The mass and charge distributions for thermal-neutron fission of U 235 are discussed in considerable detail and compared with the corresponding distributions in other low-energy fission processes. Points discussed in connection with the mass distributions for binary fission include the positions of the peaks, valley and fine structure in a mass yield curve with respect to filled nuclear shells and the changes in the positions that occur with changing fissioning nucleus and excitation energy. The mass distribution from ternary fission is discussed also. For both binary and ternary fission comments are made concerning the mass distributions of primary fragments (before neutron evaporation) and of fission products (after neutron evaporation). Charge distribution is discussed in terms of charge dispersion among fission products with the same mass number and the variation with mass number of Zp, the ''most probable charge'' (non-integral) for a given mass number. Although direct information about charge distribution is limited to fission products, estimates are presented of charge distribution for primary fission fragments. Knowledge and estimates of mass and charge distribution for a fission process allow estimation of primary yields of all fission products or fragments. Although many estimated primary yields are quite uncertain mainly because of lack of knowledge of charge distribution, especially for fission products formed in low yield; some estimates of primary yields are presented to illustrate the need for and possible practicality of further experimentation. Fission processes other than thermal-neutron fission of U 235 that are discussed include thermal-neutron fission of U 233 and Pu 239 , spontaneous fission of Pu 240 and Cf 252 , 14-MeV neutron fission of U 235 and U 238 , 11-MeV proton fission of Ra 226 and 22-MeV deuteron fission of Bi 209 . (author) [fr

  17. Effects of imatinib mesylate on the spontaneous activity generated by the guinea-pig prostate.

    Science.gov (United States)

    Lam, Michelle; Dey, Anupa; Lang, Richard J; Exintaris, Betty

    2013-08-01

    What's known on the subject? and what does the study add?: Several studies have examined the functional role of tyrosine kinase receptors in the generation of spontaneous activity in various segments of the gastrointestinal and urogenital tracts through the application of its inhibitor, imatinib mesylate (Glivec®), but results are fairly inconsistent. This is the first study detailing the effects of imatinib mesylate on the spontaneous activity in the young and ageing prostate gland. As spontaneous electrical activity underlies the spontaneous rhythmic prostatic contractions that occur at rest, elucidating the mechanisms involved in the regulation of the spontaneous electrical activity and the resultant phasic contractions could conceivably lead to the identification of better targets and the development of more specific therapeutic agents to treat prostate conditions. To investigate the effect of imatinib mesylate, a tyrosine kinase receptor inhibitor, in the generation of spontaneous electrical and contractile activity in the young and ageing guinea-pig prostate. Standard tension and intracellular recording were used to measure spontaneous contractions and slow waves, respectively from the guinea-pig prostate at varying concentrations of imatinib mesylate (1-50 μm). Imatinib mesylate (1-10 μm), did not significantly affect slow waves recorded in the prostate of both age groups but at 50 μm, the amplitude of slow waves from the ageing guinea-pig prostate was significantly reduced (P imatinib mesylate attenuated the amplitude and slowed the frequency of contractions in ageing guinea-pigs to 5.15% and 3.3% at 1 μm (n = 6); 21.1% and 20.8% at 5 μm (n = 8); 58.4% and 8.8% at 10 μm (n = 11); 72.7% and 60% at 50 μm (n = 5). A significant reduction in contractions but persistence of slow waves suggests imatinib mesylate may affect the smooth muscle contractile mechanism. Imatinib mesylate also significantly reduced contractions in the prostates of younger guinea

  18. Apatite fission track analysis on tectonic activities and paleotopography in southern Altai region, Xinjiang, China

    International Nuclear Information System (INIS)

    Zhao Wenju; Yuan Wanming; Liu Haotao; Song Gao

    2013-01-01

    This work engages apatite fission track evidences on thermotectonic history, rock uplift rate, denudation extent southeastern Altai region. Fission track ages of 14 samples range from (59.4±5.8) Ma to (109.7±8.1) Ma and the length is between (12.0±2.5) μm and (13.7±1.5) μm. Thermal modeling reveals that the samples have a three-stage of uplift-cooling history. The first stage is in an overall initial uplift before 108 Ma, the second stage from 108 Ma to 28 Ma experiences a slow cooling phase, and the last stage through a rapid-cooling process since 28 Ma with a cooling rate 1.25 1.61 ℃/Ma and denudation amount 1.17-1.50 km, the fast exhumation period in the area. The sample ages could be divided into 4 age groups, reflecting multiple tectonic events with different uplift rates. The paleotopography altitude changes from 3895 m to 821 m, 2250 m to 762 m etc., and the amplitude of changes reaches to 3300-1400 m since 90 Ma. The phenomenon of Alpine turning to valley and valley uplifting is visible in the studied area, indicating various stages of paleotopography. Based on inversion of ancient landforms and equilibrium correction, the equilibrium rebound would play an important role in the rock uplift during the Altai post-orogenic period. (authors)

  19. Nondestructive analysis of the RA fuel burnup, Calculation of the gamma activity ratio of fission products in the fuel - program QU0C1

    International Nuclear Information System (INIS)

    Bulovic, V.F.

    1973-01-01

    The γ radiation of RA reactor fuel element was measured under precisely defined measuring conditions. The spectrum was analysed by spectrometer with semiconductor Ge(Li) detector. The gamma counting rate in the fuel spectrum is defined as a function of fission product activity, gamma energy and yield, fuel thickness and additional absorbers, dimensions of the gamma collimator. Activity ratio of two fission products is defined as a function of counting rate peaks and part of the mentioned quantities. Four options for calculating the activities for fission products are discussed. Three of them are covered by the QU0C1 code written in FORTRAN for the CDC 3600 computer. The code is included in this report [sr

  20. Presbycusis Disrupts Spontaneous Activity Revealed by Resting-State Functional MRI

    Directory of Open Access Journals (Sweden)

    Yu-Chen Chen

    2018-03-01

    Full Text Available Purpose: Presbycusis, age-related hearing loss, is believed to involve neural changes in the central nervous system, which is associated with an increased risk of cognitive impairment. The goal of this study was to determine if presbycusis disrupted spontaneous neural activity in specific brain areas involved in auditory processing, attention and cognitive function using resting-state functional magnetic resonance imaging (fMRI approach.Methods: Hearing and resting-state fMRI measurements were obtained from 22 presbycusis patients and 23 age-, sex- and education-matched healthy controls. To identify changes in spontaneous neural activity associated with age-related hearing loss, we compared the amplitude of low-frequency fluctuations (ALFF and regional homogeneity (ReHo of fMRI signals in presbycusis patients vs. controls and then determined if these changes were linked to clinical measures of presbycusis.Results: Compared with healthy controls, presbycusis patients manifested decreased spontaneous activity mainly in the superior temporal gyrus (STG, parahippocampal gyrus (PHG, precuneus and inferior parietal lobule (IPL as well as increased neural activity in the middle frontal gyrus (MFG, cuneus and postcentral gyrus (PoCG. A significant negative correlation was observed between ALFF/ReHo activity in the STG and average hearing thresholds in presbycusis patients. Increased ALFF/ReHo activity in the MFG was positively correlated with impaired Trail-Making Test B (TMT-B scores, indicative of impaired cognitive function involving the frontal lobe.Conclusions: Presbycusis patients have disrupted spontaneous neural activity reflected by ALFF and ReHo measurements in several brain regions; these changes are associated with specific cognitive performance and speech/language processing. These findings mainly emphasize the crucial role of aberrant resting-state ALFF/ReHo patterns in presbycusis patients and will lead to a better understanding of the

  1. Presbycusis Disrupts Spontaneous Activity Revealed by Resting-State Functional MRI.

    Science.gov (United States)

    Chen, Yu-Chen; Chen, Huiyou; Jiang, Liang; Bo, Fan; Xu, Jin-Jing; Mao, Cun-Nan; Salvi, Richard; Yin, Xindao; Lu, Guangming; Gu, Jian-Ping

    2018-01-01

    Purpose : Presbycusis, age-related hearing loss, is believed to involve neural changes in the central nervous system, which is associated with an increased risk of cognitive impairment. The goal of this study was to determine if presbycusis disrupted spontaneous neural activity in specific brain areas involved in auditory processing, attention and cognitive function using resting-state functional magnetic resonance imaging (fMRI) approach. Methods : Hearing and resting-state fMRI measurements were obtained from 22 presbycusis patients and 23 age-, sex- and education-matched healthy controls. To identify changes in spontaneous neural activity associated with age-related hearing loss, we compared the amplitude of low-frequency fluctuations (ALFF) and regional homogeneity (ReHo) of fMRI signals in presbycusis patients vs. controls and then determined if these changes were linked to clinical measures of presbycusis. Results : Compared with healthy controls, presbycusis patients manifested decreased spontaneous activity mainly in the superior temporal gyrus (STG), parahippocampal gyrus (PHG), precuneus and inferior parietal lobule (IPL) as well as increased neural activity in the middle frontal gyrus (MFG), cuneus and postcentral gyrus (PoCG). A significant negative correlation was observed between ALFF/ReHo activity in the STG and average hearing thresholds in presbycusis patients. Increased ALFF/ReHo activity in the MFG was positively correlated with impaired Trail-Making Test B (TMT-B) scores, indicative of impaired cognitive function involving the frontal lobe. Conclusions : Presbycusis patients have disrupted spontaneous neural activity reflected by ALFF and ReHo measurements in several brain regions; these changes are associated with specific cognitive performance and speech/language processing. These findings mainly emphasize the crucial role of aberrant resting-state ALFF/ReHo patterns in presbycusis patients and will lead to a better understanding of the

  2. A gravimetric method for the measurement of total spontaneous activity in rats.

    Science.gov (United States)

    Biesiadecki, B J; Brand, P H; Koch, L G; Britton, S L

    1999-10-01

    Currently available methods for the measurement of spontaneous activity of laboratory animals require expensive, specialized equipment and may not be suitable for use in low light conditions with nocturnal species. We developed a gravimetric method that uses common laboratory equipment to quantify the total spontaneous activity of rats and is suitable for use in the dark. The rat in its home cage is placed on a top-loading electronic balance interfaced to a computer. Movements are recorded by the balance as changes in weight and transmitted to the computer at 10 Hz. Data are analyzed on-line to derive the absolute value of the difference in weight between consecutive samples, and the one-second average of the absolute values is calculated. The averages are written to file for off-line analysis and summed over the desired observation period to provide a measure of total spontaneous activity. The results of in vitro experiments demonstrated that: 1) recorded weight changes were not influenced by position of the weight on the bottom of the cage, 2) values recorded from a series of weight changes were not significantly different from the calculated values, 3) the constantly decreasing force exerted by a swinging pendulum placed on the balance was accurately recorded, 4) the measurement of activity was not influenced by the evaporation of a fluid such as urine, and 5) the method can detect differences in the activity of sleeping and waking rats over a 10-min period, as well as during 4-hr intervals recorded during active (night-time) and inactive (daytime) periods. These results demonstrate that this method provides an inexpensive, accurate, and noninvasive method to quantitate the spontaneous activity of small animals.

  3. Human embryonic stem cell-derived neuronal cells form spontaneously active neuronal networks in vitro.

    Science.gov (United States)

    Heikkilä, Teemu J; Ylä-Outinen, Laura; Tanskanen, Jarno M A; Lappalainen, Riikka S; Skottman, Heli; Suuronen, Riitta; Mikkonen, Jarno E; Hyttinen, Jari A K; Narkilahti, Susanna

    2009-07-01

    The production of functional human embryonic stem cell (hESC)-derived neuronal cells is critical for the application of hESCs in treating neurodegenerative disorders. To study the potential functionality of hESC-derived neurons, we cultured and monitored the development of hESC-derived neuronal networks on microelectrode arrays. Immunocytochemical studies revealed that these networks were positive for the neuronal marker proteins beta-tubulin(III) and microtubule-associated protein 2 (MAP-2). The hESC-derived neuronal networks were spontaneously active and exhibited a multitude of electrical impulse firing patterns. Synchronous bursts of electrical activity similar to those reported for hippocampal neurons and rodent embryonic stem cell-derived neuronal networks were recorded from the differentiated cultures until up to 4 months. The dependence of the observed neuronal network activity on sodium ion channels was examined using tetrodotoxin (TTX). Antagonists for the glutamate receptors NMDA [D(-)-2-amino-5-phosphonopentanoic acid] and AMPA/kainate [6-cyano-7-nitroquinoxaline-2,3-dione], and for GABAA receptors [(-)-bicuculline methiodide] modulated the spontaneous electrical activity, indicating that pharmacologically susceptible neuronal networks with functional synapses had been generated. The findings indicate that hESC-derived neuronal cells can generate spontaneously active networks with synchronous communication in vitro, and are therefore suitable for use in developmental and drug screening studies, as well as for regenerative medicine.

  4. Sub-threshold spinal cord stimulation facilitates spontaneous motor activity in spinal rats

    Science.gov (United States)

    2013-01-01

    Background Epidural stimulation of the spinal cord can be used to enable stepping on a treadmill (electrical enabling motor control, eEmc) after a complete mid-thoracic spinal cord transection in adult rats. Herein we have studied the effects of eEmc using a sub-threshold intensity of stimulation combined with spontaneous load-bearing proprioception to facilitate hindlimb stepping and standing during daily cage activity in paralyzed rats. Methods We hypothesized that eEmc combined with spontaneous cage activity would greatly increase the frequency and level of activation of the locomotor circuits in paralyzed rats. Spontaneous cage activity was recorded using a specially designed swivel connector to record EMG signals and an IR based camcorder to record video. Results and conclusion The spinal rats initially were very lethargic in their cages showing little movement. Without eEmc, the rats remained rather inactive with the torso rarely being elevated from the cage floor. When the rats used their forelimbs to move, the hindlimbs were extended and dragged behind with little or no flexion. In contrast, with eEmc the rats were highly active and the hindlimbs showed robust alternating flexion and extension resulting in step-like movements during forelimb-facilitated locomotion and often would stand using the sides of the cages as support. The mean and summed integrated EMG levels in both a hindlimb flexor and extensor muscle were higher with than without eEmc. These data suggest that eEmc, in combination with the associated proprioceptive input, can modulate the spinal networks to significantly amplify the amount and robustness of spontaneous motor activity in paralyzed rats. PMID:24156340

  5. Computational Account of Spontaneous Activity as a Signature of Predictive Coding.

    Directory of Open Access Journals (Sweden)

    Veronika Koren

    2017-01-01

    Full Text Available Spontaneous activity is commonly observed in a variety of cortical states. Experimental evidence suggested that neural assemblies undergo slow oscillations with Up ad Down states even when the network is isolated from the rest of the brain. Here we show that these spontaneous events can be generated by the recurrent connections within the network and understood as signatures of neural circuits that are correcting their internal representation. A noiseless spiking neural network can represent its input signals most accurately when excitatory and inhibitory currents are as strong and as tightly balanced as possible. However, in the presence of realistic neural noise and synaptic delays, this may result in prohibitively large spike counts. An optimal working regime can be found by considering terms that control firing rates in the objective function from which the network is derived and then minimizing simultaneously the coding error and the cost of neural activity. In biological terms, this is equivalent to tuning neural thresholds and after-spike hyperpolarization. In suboptimal working regimes, we observe spontaneous activity even in the absence of feed-forward inputs. In an all-to-all randomly connected network, the entire population is involved in Up states. In spatially organized networks with local connectivity, Up states spread through local connections between neurons of similar selectivity and take the form of a traveling wave. Up states are observed for a wide range of parameters and have similar statistical properties in both active and quiescent state. In the optimal working regime, Up states are vanishing, leaving place to asynchronous activity, suggesting that this working regime is a signature of maximally efficient coding. Although they result in a massive increase in the firing activity, the read-out of spontaneous Up states is in fact orthogonal to the stimulus representation, therefore interfering minimally with the network

  6. Fission track dating evidence on tectonic activities of northern Himalaya block

    International Nuclear Information System (INIS)

    Yuan Wanming; Wang Shicheng; Wang Lanfen

    2002-01-01

    Fission track ages (FTA) of 4 apatite samples collected from Langkazi to Yarlung Zangbo thrust zone range between 13.6 and 17.2 Ma, reflecting the time of continent-continent collision and differing from previous data. The negative correlation between the FTA and sample elevations shows there was rapid uplifting during the continent-continent collision with uplifting rate of 176 m/Ma. Denudation degree, denudation rate and cooling rate were ∼2.9 km, 213 m/Ma and 7 degree C/Ma respectively since 13.6 Ma. FTA of 3 zircon samples are different significantly and have x 2 test value of < 0.1%, confirming the orogeny within continent went under low temperature

  7. New fission-neutron-spectrum representation for ENDF

    International Nuclear Information System (INIS)

    Madland, D.G.

    1982-04-01

    A new representation of the prompt fission neutron spectrum is proposed for use in the Evaluated Nuclear Data File (ENDF). The proposal is made because a new theory exists by which the spectrum can be accurately predicted as a function of the fissioning nucleus and its excitation energy. Thus, prompt fission neutron spectra can be calculated for cases where no measurements exist or where measurements are not possible. The mathematical formalism necessary for application of the new theory within ENDF is presented and discussed for neutron-induced fission and spontaneous fission. In the case of neutron-induced fission, expressions are given for the first-chance, second-chance, third-chance, and fourth-chance fission components of the spectrum together with that for the total spectrum. An ENDF format is proposed for the new fission spectrum representation, and an example of the use of the format is given

  8. The wiring of developing sensory circuits - from patterned spontaneous activity to mechanisms of synaptic plasticity

    Directory of Open Access Journals (Sweden)

    Alexandra Helen Leighton

    2016-09-01

    Full Text Available In order to accurately process incoming sensory stimuli, neurons must be organized into functional networks, with both genetic and environmental factors influencing the precise arrangement of connections between cells. Teasing apart the relative contributions of molecular guidance cues, spontaneous activity and visual experience during this maturation is on-going. During development of the sensory system, the first, rough organization of connections is created by molecular factors. These connections are then modulated by the intrinsically generated activity of neurons, even before the senses have become operational. Spontaneous waves of depolarisations sweep across the nervous system, placing them in a prime position to strengthen correct connections and weaken others, shaping synapses into a useful network. A large body of work now supports the idea that, rather than being a mere side-effect of the system, spontaneous activity actually contains information which readies the nervous system so that, as soon as the senses become active, sensory information can be utilized by the animal. An example is the neonatal mouse. As soon as the eyelids first open, neurons in the cortex respond to visual information without the animal having previously encountered structured sensory input (Cang et al., 2005a; Ko et al., 2013; Rochefort et al., 2011; Zhang et al., 2012. In vivo imaging techniques have advanced considerably, allowing observation of the natural activity in the brain of living animals down to the level of the individual synapse. New (optogenetic methods make it possible to subtly modulate the spatio-temporal properties of activity, aiding our understanding of how these characteristics relate to the function of spontaneous activity. Such experiments have had a huge impact on our knowledge by permitting direct testing of ideas about the plasticity mechanisms at play in the intact system, opening up a provocative range of fresh questions. Here, we

  9. 14. International workshop on nuclear fission physics. Proceedings

    International Nuclear Information System (INIS)

    2000-01-01

    The meetings on nuclear fission took place 12-15 October 1998 and was organized by Institute of Physics and Power Engineering. The aim of the workshop was to present and discuss main new both theoretical and experimental results obtained in the area of nuclear fission, dynamical feature, properties of fission fragments and complementary radiation. As usual the program of the workshop was designed to cover a wide range of physical phenomena - from low energy and spontaneous fission to fission of hot rotating nuclei and multifragmentation at intermediate and high energies. Reaction induced by slow and fast neutron, light and heavy ions were discussed [ru

  10. Spontaneous nitroblue-tetrazolium (NBT) reduction related to granulocyte priming and activation.

    Science.gov (United States)

    Wikström, T; Braide, M; Bagge, U; Risberg, B

    1996-06-01

    The aim of the present study was to explore the relationship between the increasing level of spontaneous NBT-reduction and the tendency for PMNs to marginate during experimental hemorrhagic shock in rats. Rat PMNs, isolated on Percoll density gradients or suspended in blood, were examined by chemiluminescence (CL), NBT-test and by their CD-18 expression and F-actin formation. The NBT-test generally produced higher numbers of activated PMNs when the cells were suspended in buffer than in whole blood, probably due to the scavenging properties of blood. The level of spontaneous NBT-reduction of PMNs in blood correlated with the magnitude of the NBT-response to f-MLP stimulation in blood and buffer. On the contrary, there were no significant correlations between spontaneous NBT reduction, CD18 expression and F-actin content. Thus, high levels of spontaneous NBT reduction in blood were associated with priming of the separated PMNs rather than increased rigidity (F-actin) or adhesiveness (CD18).

  11. Spatiotemporal stability of neonatal rat cardiomyocyte monolayers spontaneous activity is dependent on the culture substrate.

    Directory of Open Access Journals (Sweden)

    Jonathan Boudreau-Béland

    Full Text Available In native conditions, cardiac cells must continuously comply with diverse stimuli necessitating a perpetual adaptation. Polydimethylsiloxane (PDMS is commonly used in cell culture to study cellular response to changes in the mechanical environment. The aim of this study was to evaluate the impact of using PDMS substrates on the properties of spontaneous activity of cardiomyocyte monolayer cultures. We compared PDMS to the gold standard normally used in culture: a glass substrate. Although mean frequency of spontaneous activity remained unaltered, incidence of reentrant activity was significantly higher in samples cultured on glass compared to PDMS substrates. Higher spatial and temporal instability of the spontaneous rate activation was found when cardiomyocytes were cultured on PDMS, and correlated with decreased connexin-43 and increased CaV3.1 and HCN2 mRNA levels. Compared to cultures on glass, cultures on PDMS were associated with the strongest response to isoproterenol and acetylcholine. These results reveal the importance of carefully selecting the culture substrate for studies involving mechanical stimulation, especially for tissue engineering or pharmacological high-throughput screening of cardiac tissue analog.

  12. The Neural Association between Tendency to Forgive and Spontaneous Brain Activity in Healthy Young Adults.

    Science.gov (United States)

    Li, Haijiang; Lu, Jiamei

    2017-01-01

    The tendency to forgive (TTF) refers to one's global dispositional level of forgiveness across situations and relationships. Previous brain imaging studies examined activation patterns underlying forgiving process, yet the association between individual differences in the TTF and spontaneous brain activity at resting-state remains unknown. In this study, resting-state functional magnetic resonance imaging (fMRI) was used to investigate the correlation between the TTF and spontaneous brain activity in a young adult sample. Participants were 178 young students (55 men) who completed the TTF scale and underwent a resting-state fMRI scan. Multiple regression analysis was conducted to assess the association between the regional amplitude of low-frequency fluctuations (ALFF) and TTF scores corrected for age and sex. Results showed that the ALFF value in the right dorsomedial prefrontal cortex (dmPFC), precuneus and inferior parietal lobule (IPL) were negatively associated with TTF scores. These findings suggest that the spontaneous brain activity of brain regions like the dmPFC, precuneus and IPL which are implicated in mentalizing and empathic response are associated with individual differences in the TTF.

  13. Changes in Mice Brain Spontaneous Electrical Activity during Cortical Spreading Depression due to Mobile Phone Radiation.

    Science.gov (United States)

    Sallam, Samera M; Mohamed, Ehab I; Dawood, Abdel-Fattah B

    2008-06-01

    The objective of the present study was to investigate changes in spontaneous EEG activity during cortical spreading depression (CSD) in mice brain. The cortical region of anaesthetized mice were exposed to the electromagnetic fields (EMFs) emitted from a mobile phone (MP, 935.2-960.2 MHz, 41.8 mW/cm(2)). The effect of EMFs on EEG was investigated before and after exposure to different stimuli (MP, 2% KCl, and MP & 2% KCl). The records of brain spontaneous EEG activity, slow potential changes (SPC), and spindle shaped firings were obtained through an interfaced computer. The results showed increases in the amplitude of evoked spindles by about 87%, 17%, and 226% for MP, 2% KCl, and MP & 2% KCl; respectively, as compared to values for the control group. These results showed that the evoked spindle is a more sensitive indicator of the effect of exposure to EMFs from MP.

  14. Endo- and exocytic rate constants for spontaneous and protein kinase C-activated T cell receptor cycling

    DEFF Research Database (Denmark)

    Menné, Charlotte; Møller Sørensen, Tine; Siersma, Volkert

    2002-01-01

    To determine the rate constants of spontaneous and activated TCR cycling, we examined TCR endo- and exocytosis in the human T cell line Jurkat by three different methods. Using a simple kinetic model for TCR cycling and non-linear regression analyses, we found that the spontaneous endocytic rate...

  15. Monte carlo sampling of fission multiplicity.

    Energy Technology Data Exchange (ETDEWEB)

    Hendricks, J. S. (John S.)

    2004-01-01

    Two new methods have been developed for fission multiplicity modeling in Monte Carlo calculations. The traditional method of sampling neutron multiplicity from fission is to sample the number of neutrons above or below the average. For example, if there are 2.7 neutrons per fission, three would be chosen 70% of the time and two would be chosen 30% of the time. For many applications, particularly {sup 3}He coincidence counting, a better estimate of the true number of neutrons per fission is required. Generally, this number is estimated by sampling a Gaussian distribution about the average. However, because the tail of the Gaussian distribution is negative and negative neutrons cannot be produced, a slight positive bias can be found in the average value. For criticality calculations, the result of rejecting the negative neutrons is an increase in k{sub eff} of 0.1% in some cases. For spontaneous fission, where the average number of neutrons emitted from fission is low, the error also can be unacceptably large. If the Gaussian width approaches the average number of fissions, 10% too many fission neutrons are produced by not treating the negative Gaussian tail adequately. The first method to treat the Gaussian tail is to determine a correction offset, which then is subtracted from all sampled values of the number of neutrons produced. This offset depends on the average value for any given fission at any energy and must be computed efficiently at each fission from the non-integrable error function. The second method is to determine a corrected zero point so that all neutrons sampled between zero and the corrected zero point are killed to compensate for the negative Gaussian tail bias. Again, the zero point must be computed efficiently at each fission. Both methods give excellent results with a negligible computing time penalty. It is now possible to include the full effects of fission multiplicity without the negative Gaussian tail bias.

  16. Spontaneous and Evoked Activity from Murine Ventral Horn Cultures on Microelectrode Arrays

    Directory of Open Access Journals (Sweden)

    Bryan J. Black

    2017-09-01

    Full Text Available Motor neurons are the site of action for several neurological disorders and paralytic toxins, with cell bodies located in the ventral horn (VH of the spinal cord along with interneurons and support cells. Microelectrode arrays (MEAs have emerged as a high content assay platform for mechanistic studies and drug discovery. Here, we explored the spontaneous and evoked electrical activity of VH cultures derived from embryonic mouse spinal cord on multi-well plates of MEAs. Primary VH cultures from embryonic day 15–16 mice were characterized by expression of choline acetyltransferase (ChAT by immunocytochemistry. Well resolved, all-or-nothing spontaneous spikes with profiles consistent with extracellular action potentials were observed after 3 days in vitro, persisting with consistent firing rates until at least day in vitro 19. The majority of the spontaneous activity consisted of tonic firing interspersed with coordinated bursting across the network. After 5 days in vitro, spike activity was readily evoked by voltage pulses where a minimum amplitude and duration required for excitation was 300 mV and 100 μs/phase, respectively. We characterized the sensitivity of spontaneous and evoked activity to a host of pharmacological agents including AP5, CNQX, strychnine, ω-agatoxin IVA, and botulinum neurotoxin serotype A (BoNT/A. These experiments revealed sensitivity of the cultured VH to both agonist and antagonist compounds in a manner consistent with mature tissue derived from slices. In the case of BoNT/A, we also demonstrated intoxication persistence over an 18-day period, followed by partial intoxication recovery induced by N- and P/Q-type calcium channel agonist GV-58. In total, our findings suggest that VH cultures on multi-well MEA plates may represent a moderate throughput, high content assay for performing mechanistic studies and for screening potential therapeutics pertaining to paralytic toxins and neurological disorders.

  17. Myofascial trigger points: spontaneous electrical activity and its consequences for pain induction and propagation

    OpenAIRE

    Ge, Hong-You; Fernández-de-las-Peñas, César; Yue, Shou-Wei

    2011-01-01

    Abstract Active myofascial trigger points are one of the major peripheral pain generators for regional and generalized musculoskeletal pain conditions. Myofascial trigger points are also the targets for acupuncture and/or dry needling therapies. Recent evidence in the understanding of the pathophysiology of myofascial trigger points supports The Integrated Hypothesis for the trigger point formation; however unanswered questions remain. Current evidence shows that spontaneous electrical activi...

  18. Rhythmic Spontaneous Activity Mediates the Age-Related Decline in Somatosensory Function.

    Science.gov (United States)

    Spooner, Rachel K; Wiesman, Alex I; Proskovec, Amy L; Heinrichs-Graham, Elizabeth; Wilson, Tony W

    2018-01-12

    Sensory gating is a neurophysiological process whereby the response to a second stimulus in a pair of identical stimuli is attenuated, and it is thought to reflect the capacity of the CNS to preserve neural resources for behaviorally relevant stimuli. Such gating is observed across multiple sensory modalities and is modulated by age, but the mechanisms involved are not understood. In this study, we examined somatosensory gating in 68 healthy adults using magnetoencephalography (MEG) and advanced oscillatory and time-domain analysis methods. MEG data underwent source reconstruction and peak voxel time series data were extracted to evaluate the dynamics of somatosensory gating, and the impact of spontaneous neural activity immediately preceding the stimulation. We found that gating declined with increasing age and that older adults had significantly reduced gating relative to younger adults, suggesting impaired local inhibitory function. Most importantly, older adults had significantly elevated spontaneous activity preceding the stimulation, and this effect fully mediated the impact of aging on sensory gating. In conclusion, gating in the somatosensory system declines with advancing age and this effect is directly tied to increased spontaneous neural activity in the primary somatosensory cortices, which is likely secondary to age-related declines in local GABA inhibitory function. © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  19. Determination of the fission barrier height in fission of heavy radioactive beams induced by the (d,p)-transfer

    CERN Multimedia

    A theoretical framework is described, allowing to determine the fission barrier height using the observed cross sections of fission induced by the (d,p)-transfer with accuracy, which is not achievable in another type of low-energy fission of neutron-deficient nuclei, the $\\beta$-delayed fission. The primary goal is to directly determine the fission barrier height of proton-rich fissile nuclei, preferably using the radio-active beams of isotopes of odd elements, and thus confirm or exclude the low values of fission barrier heights, typically extracted using statistical calculations in the compound nucleus reactions at higher excitation energies. Calculated fission cross sections in transfer reactions of the radioactive beams show sufficient sensitivity to fission barrier height. In the probable case that fission rates will be high enough, mass asymmetry of fission fragments can be determined. Results will be relevant for nuclear astrophysics and for production of super-heavy nuclei. Transfer induced fission of...

  20. Reproduction of overall spontaneous pain pattern by manual stimulation of active myofascial trigger points in fibromyalgia patients

    DEFF Research Database (Denmark)

    Ge, Hong-You; Wang, Ying; Fernández-de-las-Peñas, César

    2011-01-01

    It has previously been reported that local and referred pain from active myofascial trigger points (MTPs) in the neck and shoulder region contribute to fibromyalgia (FM) pain and that the pain pattern induced from active MTPs can reproduce parts of the spontaneous clinical FM pain pattern....... The current study investigated whether the overall spontaneous FM pain pattern can be reproduced by local and referred pain from active MTPs located in different muscles....

  1. Prophage spontaneous activation promotes DNA release enhancing biofilm formation in Streptococcus pneumoniae.

    Directory of Open Access Journals (Sweden)

    Margarida Carrolo

    Full Text Available Streptococcus pneumoniae (pneumococcus is able to form biofilms in vivo and previous studies propose that pneumococcal biofilms play a relevant role both in colonization and infection. Additionally, pneumococci recovered from human infections are characterized by a high prevalence of lysogenic bacteriophages (phages residing quiescently in their host chromosome. We investigated a possible link between lysogeny and biofilm formation. Considering that extracellular DNA (eDNA is a key factor in the biofilm matrix, we reasoned that prophage spontaneous activation with the consequent bacterial host lysis could provide a source of eDNA, enhancing pneumococcal biofilm development. Monitoring biofilm growth of lysogenic and non-lysogenic pneumococcal strains indicated that phage-infected bacteria are more proficient at forming biofilms, that is their biofilms are characterized by a higher biomass and cell viability. The presence of phage particles throughout the lysogenic strains biofilm development implicated prophage spontaneous induction in this effect. Analysis of lysogens deficient for phage lysin and the bacterial major autolysin revealed that the absence of either lytic activity impaired biofilm development and the addition of DNA restored the ability of mutant strains to form robust biofilms. These findings establish that limited phage-mediated host lysis of a fraction of the bacterial population, due to spontaneous phage induction, constitutes an important source of eDNA for the S. pneumoniae biofilm matrix and that this localized release of eDNA favors biofilm formation by the remaining bacterial population.

  2. Physics and chemistry of fission

    International Nuclear Information System (INIS)

    1979-01-01

    Full text: In the pleasant and hospitable atmosphere of the Kernforschungsanlage Juelich in the Federal Republic of Germany, the IAEA symposium on the Physics and Chemistry of Fission took place. Almost 200 scientists attended, 154 abstracts were submitted, and 57 papers presented, but more important than the numbers was the quality of the contributions and the progress reported at the symposium. The neutron was discovered almost 50 years ago; 40 years ago the idea of nuclear fission was born. Since then, a number of laboratories have worked hard to explain the phenomenon of fission One would expect that by now scientists would know exactly what happens in a nucleus before and during the process of fission, particularly as there are hundreds of power and research reactors in operation, and fission of uranium isotopes is the basis of their functioning. At first glance, fission seems a simple process: a neutron hits and penetrates the uranium nucleus which becomes excited, i.e. has a surplus of energy. One way to get rid of this energy is for the nucleus to split into two parts; additional products of this process are energy and more neutrons. Nature, however, seems to dislike such straightforward explanations. In the case of fission, scientists have observed a number of phenomena which disagree with a simple model. Sometimes, a nucleus will split into two parts without being 'attacked' by a neutron; this spontaneous fission opens up a new line of fission research and several contributions at the symposium reported on sophisticated experiments designed to unravel some of its specific details. Sometimes, a fissioning nucleus will emit another particle: ternary fission has become a powerful tool for studying the properties of nuclei during the fission process. For the scientist, it is fascinating to observe how the nucleus behaves during fission. They invent models which are supposed to reproduce the most probable course of events leading to fission. In one of these

  3. ATP enhances spontaneous calcium activity in cultured suburothelial myofibroblasts of the human bladder.

    Directory of Open Access Journals (Sweden)

    Sheng Cheng

    Full Text Available BACKGROUND: Suburothelial myofibroblasts (sMF are located underneath the urothelium in close proximity to afferent nerves. They express purinergic receptors and show calcium transients in response to ATP. Therefore they are supposed to be involved in afferent signaling of the bladder fullness. Since ATP concentration is likely to be very low during the initial filling phase, we hypothesized that sMF Ca(2+ activity is affected even at very low ATP concentrations. We investigated ATP induced modulation of spontaneous activity, intracellular calcium response and purinergic signaling in cultured sMF. METHODOLOGY/PRINCIPAL FINDINGS: Myofibroblast cultures, established from cystectomies, were challenged by exogenous ATP in presence or absence of purinergic antagonist. Fura-2 calcium imaging was used to monitor ATP (10(-16 to 10(-4 mol/l induced alterations of calcium activity. Purinergic receptors (P2X1, P2X2, P2X3 were analysed by confocal immunofluorescence. We found spontaneous calcium activity in 55.18% ± 1.65 of the sMF (N = 48 experiments. ATP significantly increased calcium activity even at 10(-16 mol/l. The calcium transients were partially attenuated by subtype selective antagonist (TNP-ATP, 1 µM; A-317491, 1 µM, and were mimicked by the P2X1, P2X3 selective agonist α,β-methylene ATP. The expression of purinergic receptor subtypes in sMF was confirmed by immunofluorescence. CONCLUSIONS/SIGNIFICANCE: Our experiments demonstrate for the first time that ATP can modulate spontaneous activity and induce intracellular Ca(2+ response in cultured sMF at very low concentrations, most likely involving P2X receptors. These findings support the notion that sMF are able to register bladder fullness very sensitively, which predestines them for the modulation of the afferent bladder signaling in normal and pathological conditions.

  4. SPONTANEOUS IMMUNOGLOBULIN-SYNTHESIZING ACTIVITY OF B LYMPHOCYTES IN INFLAMMATORY RHEUMATIC DISEASES

    Directory of Open Access Journals (Sweden)

    A.T. T. Mamasaidov

    2007-01-01

    Full Text Available Abstract. The aim of present work was to evaluate clinical significance of B-lymphocytes spontaneous antibody-synthesizing activity by B-lymphocytes (LASA in patients with rheumatic inflammatory diseases (RD, i.e., reactive arthritis (ReA, ankylosing spondylitis (AS, rheumatoid arthritis (RA, and systemic lupus erythematosus (SLE. Significantly higher LASA levels were revealed in the patients with ReA, AS, RA, and SLE, as compared with healthy persons and patients with osteoarthrosis. Clinical significance of LASA indexes and their changes may reflect manifestation and degree of immunological activities in ReA, AS, RA, and SLE.

  5. (d,p)-transfer induced fission of heavy radioactive beams

    CERN Document Server

    Veselsky, Martin

    2012-01-01

    (d,p)-transfer induced fission is proposed as a tool to study low energy fission of exotic heavy nuclei. Primary goal is to directly determine the fission barrier height of proton-rich fissile nuclei, preferably using the radio-active beams of isotopes of odd elements, and thus confirm or exclude the low values of fission barrier heights, typically extracted using statistical calculations in the compound nucleus reactions at higher excitation energies. Calculated fission cross sections in transfer reactions of the radioactive beams show sufficient sensitivity to fission barrier height. In the probable case that fission rates will be high enough, mass asymmetry of fission fragments can be determined. Results will be relevant for nuclear astrophysics and for production of super-heavy nuclei. Transfer induced fission offers a possibility for systematic study the low energy fission of heavy exotic nuclei at the ISOLDE.

  6. Myofascial trigger points: spontaneous electrical activity and its consequences for pain induction and propagation

    Science.gov (United States)

    2011-01-01

    Active myofascial trigger points are one of the major peripheral pain generators for regional and generalized musculoskeletal pain conditions. Myofascial trigger points are also the targets for acupuncture and/or dry needling therapies. Recent evidence in the understanding of the pathophysiology of myofascial trigger points supports The Integrated Hypothesis for the trigger point formation; however unanswered questions remain. Current evidence shows that spontaneous electrical activity at myofascial trigger point originates from the extrafusal motor endplate. The spontaneous electrical activity represents focal muscle fiber contraction and/or muscle cramp potentials depending on trigger point sensitivity. Local pain and tenderness at myofascial trigger points are largely due to nociceptor sensitization with a lesser contribution from non-nociceptor sensitization. Nociceptor and non-nociceptor sensitization at myofascial trigger points may be part of the process of muscle ischemia associated with sustained focal muscle contraction and/or muscle cramps. Referred pain is dependent on the sensitivity of myofascial trigger points. Active myofascial trigger points may play an important role in the transition from localized pain to generalized pain conditions via the enhanced central sensitization, decreased descending inhibition and dysfunctional motor control strategy. PMID:21439050

  7. Myofascial trigger points: spontaneous electrical activity and its consequences for pain induction and propagation.

    Science.gov (United States)

    Ge, Hong-You; Fernández-de-Las-Peñas, César; Yue, Shou-Wei

    2011-03-25

    Active myofascial trigger points are one of the major peripheral pain generators for regional and generalized musculoskeletal pain conditions. Myofascial trigger points are also the targets for acupuncture and/or dry needling therapies. Recent evidence in the understanding of the pathophysiology of myofascial trigger points supports The Integrated Hypothesis for the trigger point formation; however unanswered questions remain. Current evidence shows that spontaneous electrical activity at myofascial trigger point originates from the extrafusal motor endplate. The spontaneous electrical activity represents focal muscle fiber contraction and/or muscle cramp potentials depending on trigger point sensitivity. Local pain and tenderness at myofascial trigger points are largely due to nociceptor sensitization with a lesser contribution from non-nociceptor sensitization. Nociceptor and non-nociceptor sensitization at myofascial trigger points may be part of the process of muscle ischemia associated with sustained focal muscle contraction and/or muscle cramps. Referred pain is dependent on the sensitivity of myofascial trigger points. Active myofascial trigger points may play an important role in the transition from localized pain to generalized pain conditions via the enhanced central sensitization, decreased descending inhibition and dysfunctional motor control strategy.

  8. Myofascial trigger points: spontaneous electrical activity and its consequences for pain induction and propagation

    Directory of Open Access Journals (Sweden)

    Fernández-de-las-Peñas César

    2011-03-01

    Full Text Available Abstract Active myofascial trigger points are one of the major peripheral pain generators for regional and generalized musculoskeletal pain conditions. Myofascial trigger points are also the targets for acupuncture and/or dry needling therapies. Recent evidence in the understanding of the pathophysiology of myofascial trigger points supports The Integrated Hypothesis for the trigger point formation; however unanswered questions remain. Current evidence shows that spontaneous electrical activity at myofascial trigger point originates from the extrafusal motor endplate. The spontaneous electrical activity represents focal muscle fiber contraction and/or muscle cramp potentials depending on trigger point sensitivity. Local pain and tenderness at myofascial trigger points are largely due to nociceptor sensitization with a lesser contribution from non-nociceptor sensitization. Nociceptor and non-nociceptor sensitization at myofascial trigger points may be part of the process of muscle ischemia associated with sustained focal muscle contraction and/or muscle cramps. Referred pain is dependent on the sensitivity of myofascial trigger points. Active myofascial trigger points may play an important role in the transition from localized pain to generalized pain conditions via the enhanced central sensitization, decreased descending inhibition and dysfunctional motor control strategy.

  9. Fractal analysis reveals subclasses of neurons and suggests an explanation of their spontaneous activity.

    Science.gov (United States)

    Favela, Luis H; Coey, Charles A; Griff, Edwin R; Richardson, Michael J

    2016-07-28

    The present work used fractal time series analysis (detrended fluctuation analysis; DFA) to examine the spontaneous activity of single neurons in an anesthetized animal model, specifically, the mitral cells in the rat main olfactory bulb. DFA bolstered previous research in suggesting two subclasses of mitral cells. Although there was no difference in the fractal scaling of the interspike interval series at the shorter timescales, there was a significant difference at longer timescales. Neurons in Group B exhibited fractal, power-law scaled interspike intervals, whereas neurons in Group A exhibited random variation. These results raise questions about the role of these different cells within the olfactory bulb and potential explanations of their dynamics. Specifically, self-organized criticality has been proposed as an explanation of fractal scaling in many natural systems, including neural systems. However, this theory is based on certain assumptions that do not clearly hold in the case of spontaneous neural activity, which likely reflects intrinsic cell dynamics rather than activity driven by external stimulation. Moreover, it is unclear how self-organized criticality might account for the random dynamics observed in Group A, and how these random dynamics might serve some functional role when embedded in the typical activity of the olfactory bulb. These theoretical considerations provide direction for additional experimental work. Published by Elsevier Ireland Ltd.

  10. Second international conference on dynamical aspects of nuclear fission. Programme and abstracts

    International Nuclear Information System (INIS)

    1994-01-01

    The proceedings contain 37 abstracts and short communications dealing with the fission of heavy nuclei. The fission is induced by neutrons or by reactions of heavy ions, or occurs spontaneously. Included are both theoretical and experimental studies. Particular attention was paid to the description of the fission mechanism and kinematics (fragments, neutrons, light ions). (S.P.)

  11. Accuracy of rate coding: When shorter time window and higher spontaneous activity help

    Czech Academy of Sciences Publication Activity Database

    Leváková, Marie; Tamborrino, M.; Košťál, Lubomír; Lánský, Petr

    2017-01-01

    Roč. 95, č. 2 (2017), č. článku 022310. ISSN 2470-0045 R&D Projects: GA ČR(CZ) GA15-08066S; GA MŠk(CZ) 7AMB17AT048 Institutional support: RVO:67985823 Keywords : rate coding * observation window * spontaneous activity * Fisher information * perfect integrate- and -fire model * Wiener process Subject RIV: BB - Applied Statistics, Operational Research OBOR OECD: Biology (theoretical, mathematical, thermal, cryobiology, biological rhythm), Evolutionary biology Impact factor: 2.366, year: 2016

  12. Angular distribution in ternary cold fission

    International Nuclear Information System (INIS)

    Delion, D.S.; J.W. Goethe Univ., Frankfurt; Sandulescu, A.; J.W. Goethe Univ., Frankfurt; Greiner, W.

    2003-01-01

    We describe the spontaneous ternary cold fission of 252 Cf, accompanied by 4 He, 10 Be and 14 C. The light cluster decays from the first resonant eigenstate in the Coulomb potential plus a harmonic oscillator potential. We have shown that the angular distribution of the emitted light particle is strongly connected with its deformation and the equatorial distance. (author)

  13. Investigation of exotic fission modes

    International Nuclear Information System (INIS)

    Poenaru, D. N.; Gherghescu, R. A.; Greiner, W.; Nagame, Y.; Hamilton, J. H.; Ramayya, A. V.

    2002-01-01

    Fission approach to the cluster radioactivities and α-decay has been systematically developed during the last two decades. A more complex process, the ternary fission, was observed since 1946 both in neutron-induced and spontaneous fission. We obtained interesting results concerning the binary fission saddle-point reflection asymmetric nuclear shapes, and we can explain how a possible nuclear quasimolecular state is formed during the 10 Be accompanied cold fission of 252 Cf. The equilibrium nuclear shapes in fission theory are usually determined by minimizing the deformation energy for a given surface equation. We developed a method allowing to obtain a very general saddle-point shape as a solution of a differential equation without an a priori introduction of a shape parametrization. In the approach based on a liquid drop model (LDM), saddle-point shapes are always reflection symmetric: the deformation energy increases with the mass-asymmetry parameter η = (A 1 - A 2 )/(A 1 + A 2 ). By adding the shell corrections to the LDM deformation energy, we obtained minima at a finite mass asymmetry for parent nuclei 238 U, 232,228 Th in agreement with experiments. This correction was calculated phenomenologically. A technique based on the fragment identification by using triple γ coincidences in the large arrays of Ge-detectors, like GAMMASPHERE, was employed at Vanderbilt University to discover new characteristics of the fission process, and new decay modes. The possibility of a whole family of new decay modes, the multicluster accompanied fission, was envisaged. Besides the fission into two or three fragments, a heavy or superheavy nucleus spontaneously breaks into four, five or six nuclei of which two are asymmetric or symmetric heavy fragments and the others are light clusters, e.g. α-particles, 10 Be, 14 C, or combinations of them. Examples were presented for the two-, three- and four cluster accompanied cold fission of 252 Cf and 262 Rf, in which the emitted

  14. Decay and fission of the oriented nuclei

    CERN Document Server

    Kadmenskij, S G

    2002-01-01

    The fragment angular distributions for binary decay of oriented spherical and deformed nuclei with taking into account the correct transformational properties of wave functions under time inversion have been investigated. It has been shown that for description of fragment angular distributions the adiabatic approximation for collective rotational nuclear degrees of freedom is not correct. It has been demonstrated that this approximation is valid for description of spontaneous and induced low-energy nuclear fission. The dependence of partial fission widths on the orientation of the internal axes spins, projections of spins, and relative angular moments of fission fragments has been analyzed. It has been shown that the adiabatic approximation results in coherent interference of wave functions of fragments relative movement. This interference forms fragments the universal angular distributions of fission fragments for oriented nuclei. For these distributions the deviations from A. Bohr's formula have been invest...

  15. Spontaneous membrane formation and self-encapsulation of active rods in an inhomogeneous motility field

    Science.gov (United States)

    Grauer, Jens; Löwen, Hartmut; Janssen, Liesbeth M. C.

    2018-02-01

    We study the collective dynamics of self-propelled rods in an inhomogeneous motility field. At the interface between two regions of constant but different motility, a smectic rod layer is spontaneously created through aligning interactions between the active rods, reminiscent of an artificial, semipermeable membrane. This "active membrane" engulfes rods which are locally trapped in low-motility regions and thereby further enhances the trapping efficiency by self-organization, an effect which we call "self-encapsulation." Our results are gained by computer simulations of self-propelled rod models confined on a two-dimensional planar or spherical surface with a stepwise constant motility field, but the phenomenon should be observable in any geometry with sufficiently large spatial inhomogeneity. We also discuss possibilities to verify our predictions of active-membrane formation in experiments of self-propelled colloidal rods and vibrated granular matter.

  16. Improved fission neutron energy discrimination with {sup 4}He detectors through pulse filtering

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Ting, E-mail: ting.zhu@ufl.edu [University of Florida, Gainesville, FL (United States); Liang, Yinong; Rolison, Lucas; Barker, Cathleen; Lewis, Jason; Gokhale, Sasmit [University of Florida, Gainesville, FL (United States); Chandra, Rico [Arktis Radiation Detectors Ltd., Räffelstrasse 11, Zürich (Switzerland); Kiff, Scott [Sandia National Laboratories, CA (United States); Chung, Heejun [Korean Institute for Nuclear Nonproliferation and Control, 1534 Yuseong-daero, Yuseong-gu, Daejeon (Korea, Republic of); Ray, Heather; Baciak, James E.; Enqvist, Andreas; Jordan, Kelly A. [University of Florida, Gainesville, FL (United States)

    2017-03-11

    This paper presents experimental and computational techniques implemented for {sup 4}He gas scintillation detectors for induced fission neutron detection. Fission neutrons are produced when natural uranium samples are actively interrogated by 2.45 MeV deuterium-deuterium fusion reaction neutrons. Fission neutrons of energies greater than 2.45 MeV can be distinguished by their different scintillation pulse height spectra since {sup 4}He detectors retain incident fast neutron energy information. To enable the preferential detection of fast neutrons up to 10 MeV and suppress low-energy event counts, the detector photomultiplier gain is lowered and trigger threshold is increased. Pile-up and other unreliable events due to the interrogating neutron flux and background radiation are filtered out prior to the evaluation of pulse height spectra. With these problem-specific calibrations and data processing, the {sup 4}He detector's accuracy at discriminating fission neutrons up to 10 MeV is improved and verified with {sup 252}Cf spontaneous fission neutrons. Given the {sup 4}He detector's ability to differentiate fast neutron sources, this proof-of-concept active-interrogation measurement demonstrates the potential of special nuclear materials detection using a {sup 4}He fast neutron detection system.

  17. Alpha-Band Activity Reveals Spontaneous Representations of Spatial Position in Visual Working Memory.

    Science.gov (United States)

    Foster, Joshua J; Bsales, Emma M; Jaffe, Russell J; Awh, Edward

    2017-10-23

    An emerging view suggests that spatial position is an integral component of working memory (WM), such that non-spatial features are bound to locations regardless of whether space is relevant [1, 2]. For instance, past work has shown that stimulus position is spontaneously remembered when non-spatial features are stored. Item recognition is enhanced when memoranda appear at the same location where they were encoded [3-5], and accessing non-spatial information elicits shifts of spatial attention to the original position of the stimulus [6, 7]. However, these findings do not establish that a persistent, active representation of stimulus position is maintained in WM because similar effects have also been documented following storage in long-term memory [8, 9]. Here we show that the spatial position of the memorandum is actively coded by persistent neural activity during a non-spatial WM task. We used a spatial encoding model in conjunction with electroencephalogram (EEG) measurements of oscillatory alpha-band (8-12 Hz) activity to track active representations of spatial position. The position of the stimulus varied trial to trial but was wholly irrelevant to the tasks. We nevertheless observed active neural representations of the original stimulus position that persisted throughout the retention interval. Further experiments established that these spatial representations are dependent on the volitional storage of non-spatial features rather than being a lingering effect of sensory energy or initial encoding demands. These findings provide strong evidence that online spatial representations are spontaneously maintained in WM-regardless of task relevance-during the storage of non-spatial features. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. MRI-constrained spectral imaging of benzodiazepine modulation of spontaneous neuromagnetic activity in human cortex.

    Science.gov (United States)

    Ahveninen, Jyrki; Lin, Fa-Hsuan; Kivisaari, Reetta; Autti, Taina; Hämäläinen, Matti; Stufflebeam, Steven; Belliveau, John W; Kähkönen, Seppo

    2007-04-01

    Spontaneous electromagnetic brain rhythms have been widely used in human neuropharmacology, but their applicability is complicated by the difficulties to localize their origins in the human cortex. Here, we used a novel multi-modal non-invasive imaging approach to localize lorazepam (30 microg/kg i.v.) modulation of cortical generators of spontaneous brain rhythms. Eight healthy subjects were measured with 306-channel magnetoencephalography (MEG) in a double-blind, randomized, placebo-controlled (saline), crossover design. For anatomically realistic source modeling, wavelet-transformed MEG data were combined with high-resolution MRI to constrain the current locations to the cortical mantle, after which individual data were co-registered to surface-based coordinate system for the calculation of group statistical parametric maps of drug effects. The distributed MRI-constrained MEG source estimates demonstrated decreased alpha (10 Hz) activity in and around the parieto-occipital sulcus and in the calcarine sulcus of the occipital lobe, following from increased GABA(A)-inhibition by lorazepam. Anatomically constrained spectral imaging displays the cortical loci of drug effects on oscillatory brain activity, providing a novel tool for human pharmacological neuroimaging.

  19. Triclosan causes spontaneous abortion accompanied by decline of estrogen sulfotransferase activity in humans and mice.

    Science.gov (United States)

    Wang, Xiaoli; Chen, Xiaojiao; Feng, Xuejiao; Chang, Fei; Chen, Minjian; Xia, Yankai; Chen, Ling

    2015-12-15

    Triclosan (TCS), an antibacterial agent, is identified in serum and urine of humans. Here, we show that the level of urinary TCS in 28.3% patients who had spontaneous abortion in mid-gestation were increased by 11.3-fold (high-TCS) compared with normal pregnancies. Oral administration of TCS (10 mg/kg/day) in mice (TCS mice) caused an equivalent urinary TCS level as those in the high-TCS abortion patients. The TCS-exposure from gestation day (GD) 5.5 caused dose-dependently fetal death during GD12.5-16.5 with decline of live fetal weight. GD15.5 TCS mice appeared placental thrombus and tissue necrosis with enhancement of platelet aggregation. The levels of placenta and plasma estrogen sulfotransferase (EST) mRNA and protein in TCS mice or high-TCS abortion patients were not altered, but their EST activities were significantly reduced compared to controls. Although the levels of serum estrogen (E2) in TCS mice and high-TCS abortion patients had no difference from controls, their ratio of sulfo-conjugated E2 and unconjugated E2 was reduced. The estrogen receptor antagonist ICI-182,780 prevented the enhanced platelet aggregation and placental thrombosis and attenuated the fetal death in TCS mice. The findings indicate that TCS-exposure might cause spontaneous abortion probably through inhibition of EST activity to produce placental thrombosis.

  20. Dopamine Attenuates Ketamine-Induced Neuronal Apoptosis in the Developing Rat Retina Independent of Early Synchronized Spontaneous Network Activity.

    Science.gov (United States)

    Dong, Jing; Gao, Lingqi; Han, Junde; Zhang, Junjie; Zheng, Jijian

    2017-07-01

    Deprivation of spontaneous rhythmic electrical activity in early development by anesthesia administration, among other interventions, induces neuronal apoptosis. However, it is unclear whether enhancement of neuronal electrical activity attenuates neuronal apoptosis in either normal development or after anesthesia exposure. The present study investigated the effects of dopamine, an enhancer of spontaneous rhythmic electrical activity, on ketamine-induced neuronal apoptosis in the developing rat retina. TUNEL and immunohistochemical assays indicated that ketamine time- and dose-dependently aggravated physiological and ketamine-induced apoptosis and inhibited early-synchronized spontaneous network activity. Dopamine administration reversed ketamine-induced neuronal apoptosis, but did not reverse the inhibitory effects of ketamine on early synchronized spontaneous network activity despite enhancing it in controls. Blockade of D1, D2, and A2A receptors and inhibition of cAMP/PKA signaling partially antagonized the protective effect of dopamine against ketamine-induced apoptosis. Together, these data indicate that dopamine attenuates ketamine-induced neuronal apoptosis in the developing rat retina by activating the D1, D2, and A2A receptors, and upregulating cAMP/PKA signaling, rather than through modulation of early synchronized spontaneous network activity.

  1. Systematics of measured fission half lives of even even superheavy nuclei

    International Nuclear Information System (INIS)

    Bhagwat, A.; Gupta, M.; Gambhir, Y.K.

    2011-01-01

    The production and study of superheavy nuclei is of current interest. Elements upto Z = 118 have been produced so far, and their decay properties have been studied in detail. In the shell stabilised superheavy region, spontaneous fission competes with decay and must be taken into account as an important decay mode. Therefore, the study of fission becomes particularly important in the context of the formation and survival of the superheavy nuclei. A fully microscopic description of the fission phenomenon and hence the fission half lives, though highly desirable, is far from being realised due to the extreme complexity of the fission process. Hence a phenomenological description of the fission process is attempted here

  2. A multiple parallel-plate avalanche counter for fission-fragment detection

    Energy Technology Data Exchange (ETDEWEB)

    Wu, C.Y., E-mail: wu24@llnl.gov [Lawrence Livermore National Laboratory, Livermore, CA 9455 (United States); Henderson, R.A. [Lawrence Livermore National Laboratory, Livermore, CA 9455 (United States); Haight, R.C.; Lee, H.Y.; Taddeucci, T.N. [Los Alamos National Laboratory, Los Alamos, MN 87545 (United States); Bucher, B.; Chyzh, A. [Lawrence Livermore National Laboratory, Livermore, CA 9455 (United States); Devlin, M.; Fotiades, N. [Los Alamos National Laboratory, Los Alamos, MN 87545 (United States); Kwan, E. [Lawrence Livermore National Laboratory, Livermore, CA 9455 (United States); National Superconducting Cyclotron Laboratory, East Lansing, MI 48824 (United States); O’Donnell, J.M.; Perdue, B.A.; Ullmann, J.L. [Los Alamos National Laboratory, Los Alamos, MN 87545 (United States)

    2015-09-11

    A new low-mass multiple gas-filled parallel-plate avalanche counter for the fission-fragment detection has been developed to mark the fission occurrence in measurements of the prompt fission neutron energy spectrum as a function of incident neutron energy. It was used successfully for the neutron-induced fission of {sup 235}U and {sup 239}Pu with a total mass near 100 mg each and the spontaneous fission of {sup 252}Cf. Both the incident neutron energy and the prompt fission neutron energy are measured by using the time-of-flight method. The design and performance of this avalanche counter are described.

  3. Energy released in fission

    International Nuclear Information System (INIS)

    James, M.F.

    1969-05-01

    The effective energy released in and following the fission of U-235, Pu-239 and Pu-241 by thermal neutrons, and of U-238 by fission spectrum neutrons, is discussed. The recommended values are: U-235 ... 192.9 ± 0.5 MeV/fission; U-238 ... 193.9 ± 0.8 MeV/fission; Pu-239 ... 198.5 ± 0.8 MeV/fission; Pu-241 ... 200.3 ± 0.8 MeV/fission. These values include all contributions except from antineutrinos and very long-lived fission products. The detailed contributions are discussed, and inconsistencies in the experimental data are pointed out. In Appendix A, the contribution to the total useful energy release in a reactor from reactions other than fission are discussed briefly, and in Appendix B there is a discussion of the variations in effective energy from fission with incident neutron energy. (author)

  4. Fission products collecting devices

    International Nuclear Information System (INIS)

    Matsumoto, Hiroshi

    1979-01-01

    Purpose: To enable fission products trap with no contamination to coolants and cover gas by the provision of a fission products trap above the upper part of a nuclear power plant. Constitution: Upon fuel failures in a reactor core, nuclear fission products leak into coolants and move along the flow of the coolants to the coolants above the reactor core. The fission products are collected in a trap container and guided along a pipeline into fission products detector. The fission products detector monitors the concentration of the fission products and opens the downstream valve of the detector when a predetermined concentration of the fission products is detected to introduce the fission products into a waste gas processing device and release them through the exhaust pipe. (Seki, T.)

  5. Distinct Temporal Coordination of Spontaneous Population Activity between Basal Forebrain and Auditory Cortex

    Directory of Open Access Journals (Sweden)

    Josue G. Yague

    2017-09-01

    Full Text Available The basal forebrain (BF has long been implicated in attention, learning and memory, and recent studies have established a causal relationship between artificial BF activation and arousal. However, neural ensemble dynamics in the BF still remains unclear. Here, recording neural population activity in the BF and comparing it with simultaneously recorded cortical population under both anesthetized and unanesthetized conditions, we investigate the difference in the structure of spontaneous population activity between the BF and the auditory cortex (AC in mice. The AC neuronal population show a skewed spike rate distribution, a higher proportion of short (≤80 ms inter-spike intervals (ISIs and a rich repertoire of rhythmic firing across frequencies. Although the distribution of spontaneous firing rate in the BF is also skewed, a proportion of short ISIs can be explained by a Poisson model at short time scales (≤20 ms and spike count correlations are lower compared to AC cells, with optogenetically identified cholinergic cell pairs showing exceptionally higher correlations. Furthermore, a smaller fraction of BF neurons shows spike-field entrainment across frequencies: a subset of BF neurons fire rhythmically at slow (≤6 Hz frequencies, with varied phase preferences to ongoing field potentials, in contrast to a consistent phase preference of AC populations. Firing of these slow rhythmic BF cells is correlated to a greater degree than other rhythmic BF cell pairs. Overall, the fundamental difference in the structure of population activity between the AC and BF is their temporal coordination, in particular their operational timescales. These results suggest that BF neurons slowly modulate downstream populations whereas cortical circuits transmit signals on multiple timescales. Thus, the characterization of the neural ensemble dynamics in the BF provides further insight into the neural mechanisms, by which brain states are regulated.

  6. Sex differences in endogenous cortical network activity: spontaneously recurring Up/Down states.

    Science.gov (United States)

    Sigalas, Charalambos; Konsolaki, Eleni; Skaliora, Irini

    2017-01-01

    Several molecular and cellular processes in the vertebrate brain exhibit differences between males and females, leading to sexual dimorphism in the formation of neural circuits and brain organization. While studies on large-scale brain networks provide ample evidence for both structural and functional sex differences, smaller-scale local networks have remained largely unexplored. In the current study, we investigate sexual dimorphism in cortical dynamics by means of spontaneous Up/Down states, a type of network activity that is exhibited during slow-wave sleep, quiet wakefulness, and anesthesia and is thought to represent the default activity of the cortex. Up state activity was monitored by local field potential recordings in coronal brain slices of male and female mice across three ages with distinct secretion profiles of sex hormones: (i) pre-puberty (17-21 days old), (ii) 3-9 adult (months old), and (iii) old (19-24 months old). Female mice of all ages exhibited longer and more frequent Up states compared to aged-matched male mice. Power spectrum analysis revealed sex differences in the relative power of Up state events, with female mice showing reduced power in the delta range (1-4 Hz) and increased power in the theta range (4-8 Hz) compared to male mice. No sex differences were found in the characteristics of Up state peak voltage and latency. The present study revealed for the first time sex differences in intracortical network activity, using an ex vivo paradigm of spontaneously occurring Up/Down states. We report significant sex differences in Up state properties that are already present in pre-puberty animals and are maintained through adulthood and old age.

  7. Research on spontaneous activity in adult anisometropic amblyopia with regional homogeneity

    Science.gov (United States)

    Huang, Yufeng; Zhou, Yifeng

    2017-06-01

    Amblyopia usually occurs in early childhood and results in monocular visual impairment. The functional magnetic resonance imaging (fMRI) studies have reflected functional anomaly in amblyopia. In resting-state fMRI study, spontaneous activity changes abnormally in anisometropic amblyopia could be revealed by the regional homogeneity (ReHo). Twenty two adult anisometropic amblyopes and Twenty one normal controls participated in this fMRI study. Two sample T test was carried out to analysis ReHo within the whole brain for the inter groups. Compare with normal group, our study found that the amblyopia’s ReHo mainly increased in the left frontal lobe, while decreased in the left cerebellum, the temporal lobe (left and right), and the left parietal lobe. And the ReHo values in middle and inferior temporal lobe, the prefrontal lobe, frontal lobe (positive) and parietal lobe and medial frontal gyrus (negative) could be correlated with the acuity deficit of amblyopia. The results increased in ReHo may indicate compensatory plasticity in higher vision information process, while the decreased in ReHo may reflect decreased ability in eye movement, spatial sense and visuo-motor coordination. The correlation revealed that the vision deficit may correspond to the spontaneous in certain brain area.

  8. Investigation of the heavy nuclei fission with anomalously high values of the fission fragments total kinetic energy

    Science.gov (United States)

    Khryachkov, Vitaly; Goverdovskii, Andrei; Ketlerov, Vladimir; Mitrofanov, Vecheslav; Sergachev, Alexei

    2018-03-01

    Binary fission of 232Th and 238U induced by fast neutrons were under intent investigation in the IPPE during recent years. These measurements were performed with a twin ionization chamber with Frisch grids. Signals from the detector were digitized for further processing with a specially developed software. It results in information of kinetic energies, masses, directions and Bragg curves of registered fission fragments. Total statistics of a few million fission events were collected during each experiment. It was discovered that for several combinations of fission fragment masses their total kinetic energy was very close to total free energy of the fissioning system. The probability of such fission events for the fast neutron induced fission was found to be much higher than for spontaneous fission of 252Cf and thermal neutron induced fission of 235U. For experiments with 238U target the energy of incident neutrons were 5 MeV and 6.5 MeV. Close analysis of dependence of fission fragment distribution on compound nucleus excitation energy gave us some explanation of the phenomenon. It could be a process in highly excited compound nucleus which leads the fissioning system from the scission point into the fusion valley with high probability.

  9. Investigation of the heavy nuclei fission with anomalously high values of the fission fragments total kinetic energy

    Directory of Open Access Journals (Sweden)

    Khryachkov Vitaly

    2018-01-01

    Full Text Available Binary fission of 232Th and 238U induced by fast neutrons were under intent investigation in the IPPE during recent years. These measurements were performed with a twin ionization chamber with Frisch grids. Signals from the detector were digitized for further processing with a specially developed software. It results in information of kinetic energies, masses, directions and Bragg curves of registered fission fragments. Total statistics of a few million fission events were collected during each experiment. It was discovered that for several combinations of fission fragment masses their total kinetic energy was very close to total free energy of the fissioning system. The probability of such fission events for the fast neutron induced fission was found to be much higher than for spontaneous fission of 252Cf and thermal neutron induced fission of 235U. For experiments with 238U target the energy of incident neutrons were 5 MeV and 6.5 MeV. Close analysis of dependence of fission fragment distribution on compound nucleus excitation energy gave us some explanation of the phenomenon. It could be a process in highly excited compound nucleus which leads the fissioning system from the scission point into the fusion valley with high probability.

  10. Outcomes of Nulliparous Women with Spontaneous Labor Onset Admitted to Hospitals in Pre-active versus Active Labor

    Science.gov (United States)

    NEAL, Jeremy L.; LAMP, Jane M.; BUCK, Jacalyn S.; LOWE, Nancy K.; GILLESPIE, Shannon L.; RYAN, Sharon L.

    2014-01-01

    Introduction The timing of when a woman is admitted to the hospital for labor care following spontaneous contraction onset may be among the most important decisions that labor attendants make as it can influence care patterns and birth outcomes. The aims of this study were to estimate the percentage of low-risk, nulliparous women at term who are admitted to labor units prior to active labor and to evaluate the effects of the timing of admission (i.e., pre-active versus active labor) on labor interventions and mode of birth. Methods Obstetrics data from low-risk, nulliparous women with spontaneous labor onset at term gestation (N = 216) were merged from two prospective studies conducted at three large, Midwestern hospitals. Baseline characteristics, labor interventions, and outcomes were compared between groups using Fisher’s exact and Mann-Whitney U tests, as appropriate. Likelihoods for oxytocin augmentation, amniotomy, and cesarean delivery were assessed by logistic regression. Results Of the sample of 216 low-risk nulliparous women, 114 (52.8%) were admitted in pre-active labor and 102 (47.2%) were admitted in active labor. Women admitted in pre-active labor were more likely to undergo oxytocin augmentation (84.2% and 45.1%, respectively; odds ratio (OR) 6.5, 95% confidence interval (CI) 3.43–12.27) but not amniotomy (55.3% and 61.8%, respectively; OR 0.8, 95% CI 0.44–1.32) when compared to women admitted in active labor. The likelihood of cesarean delivery was higher for women admitted before active labor onset (15.8% and 6.9%, respectively; OR 2.6, 95% CI 1.02–6.37). Discussion Many low-risk nulliparous women with regular, spontaneous uterine contractions are admitted to labor units before active labor onset, which increases their likelihood of receiving oxytocin and being delivered via cesarean section. An evidence-based, standardized approach for labor admission decision-making is recommended to decrease inadvertent admissions of women in pre-active

  11. Historical evolution of nuclear energy systems development and related activities in JAERI. Fission, fusion, accelerator utilization

    Energy Technology Data Exchange (ETDEWEB)

    Tone, Tatsuzo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-03-01

    Overview of the historical evolution of nuclear energy systems development and related activities in JAERI is given in the report. This report reviews the research and development for light water reactor, fast breeder reactor, high temperature gas reactor, fusion reactor and utilization of accelerator-based neutron source. (author)

  12. Proof of Principle for Active Detection of Fissionable Material Using Intense, Pulsed-Bremsstrahlung-Induced Photofission

    Science.gov (United States)

    2014-10-07

    reasonable approximation, is presently being investigated using neutron detection data taken from a Van de Graaff accelerator. The large event-number...bremsstrahlung from the Naval Research Laboratory Mercury pulsed-power generator (200-kA peak current, 50-ns pulse width) induces photofission in...single pulse is generally termed intense, pulsed, active detection (IPAD).15 The high-power electrical pulse is used to create a short (~ 100 ns

  13. Nuclear data for neutron emission in the fission process

    International Nuclear Information System (INIS)

    Ganesan, S.

    1991-11-01

    This document contains the proceedings of the IAEA Consultants' Meeting on Nuclear Data for Neutron Emission in the Fission Process, Vienna, 22 - 24 October 1990. Included are the conclusions and recommendations reached at the meeting and the papers presented by the meeting participants. These papers provide a review of the status of experimental and theoretical data on neutron emission in spontaneous and neutron induced fission with reference to the data needs for reactor applications oriented towards actinide burner studies. The specific topics covered are the following: experimental measurements and theoretical predictions and evaluations of fission neutron energy spectra, average prompt fission neutron multiplicity, correlation in neutron emission from complementary fragments, neutron emission during acceleration of fission fragments, statistical properties of neutron rich nuclei by study of emission spectra of neutrons from the excited fission fragments, integral qualification of nu-bar for the major fissile isotopes, nu-bar total of 239 Pu and 235 U, and related problems. Refs figs and tabs

  14. Comparative study of 99Mo/99mTc generators at base of synthesized gels starting from activation and fission 99Mo

    International Nuclear Information System (INIS)

    Lopez M, I.Z.; Monroy G, F.; Rivero G, T.; Rojas N, P.

    2007-01-01

    The 99m Tc is used for diagnostic and therapy. It is produced starting from 99 Mo, absorbed in chromatographic columns, loaded with alumina that absorb only 0.2% of 99 Mo with high specific activities of 99 Mo, obtained from the 235 U fission. Given these conditions and limitations, new preparation procedures of 99 Mo/ 99m Tc generators, its have been developed, using zirconium molybdates gels that incorporates until 30% of 99 Mo, conserve similar characteristics of quality and purity that the traditional generator. The radiochemical characteristics of the 99m Tc elution, depend strongly on the gel preparation conditions. In particular, the present work has by object to determine the influence of the 99 Mo used type, fission or activation product, during the gels synthesis, as well as the used air flow for the agitation in the gels preparation and its influence in the 99 Mo/ 99m Tc generators quality. When diminishing the flow of agitation air the efficiency it increases and in the radionuclide purity of the eluates and when using 99 Mo from fission for the gels production it increases in an important way the elutriation efficiency, the radiochemical and radionuclide purity of the 99m Tc eluates. (Author)

  15. Reproduction of overall spontaneous pain pattern by manual stimulation of active myofascial trigger points in fibromyalgia patients

    DEFF Research Database (Denmark)

    Ge, Hong-You; Wang, Ying; Fernández-de-las-Peñas, César

    2011-01-01

    It has previously been reported that local and referred pain from active myofascial trigger points (MTPs) in the neck and shoulder region contribute to fibromyalgia (FM) pain and that the pain pattern induced from active MTPs can reproduce parts of the spontaneous clinical FM pain pattern...

  16. Reproduction of overall spontaneous pain pattern by manual stimulation of active myofascial trigger points in fibromyalgia patients

    DEFF Research Database (Denmark)

    Ge, Hong-You; Wang, Ying; Fernandez-de-las-Penas, Cesar

    2011-01-01

    It has previously been reported that local and referred pain from active myofascial trigger points (MTPs) in the neck and shoulder region contribute to fibromyalgia (FM) pain and that the pain pattern induced from active MTPs can reproduce parts of the spontaneous clinical FM pain pattern. The cu...

  17. Fission fragment angular distributions and fission cross section validation

    International Nuclear Information System (INIS)

    Leong, Lou Sai

    2013-01-01

    sphere was surrounded by enriched uranium 235 U so as to approach criticality with fast neutrons. The simulation predicts a multiplication factor k eff in better agreement with the experiment (the deviation of 750 pcm is reduced to 250 pcm) when we replace the ENDF/B- VII.0 evaluation of the 237 Np fission cross section by the n-TOF data. We also explore the hypothesis of deficiencies of the inelastic cross section in 235 U which has been invoked by some authors to explain the deviation of 750 pcm. The large distortion that should be applied to the inelastic cross sections in order to reconcile the critical experiment with its simulation is incompatible with existing measurements. Also we show that the ν-bar of 237 Np can hardly be incriminated because of the high accuracy of the existing data. Fission rate ratios or averaged fission cross sections measured in several fast neutron fields seem to give contradictory results on the validation of the 237 Np cross section but at least one of the benchmark experiments, where the active deposits have been well calibrated for the number of atoms, favors the n-TOF data set. These outcomes support the hypothesis of a higher fission cross section of 237 Np. (author)

  18. ANTIMICROBIAL ACTIVITY OF EXTRACTS OF WILD GARLIC (Allium ursinum FROM ROMANIAN SPONTANEOUS FLORA

    Directory of Open Access Journals (Sweden)

    MARIANA LUPOAE

    2014-05-01

    Full Text Available Wild Romanian spontaneous garlic’s (Allium ursinum antimicrobial activity was tested in order to establish the inhibition potential of growth of some microorganisms. As test microorganisms were used pure cultures of fungs (Aspergillus glaucus, Geotrichum candidum, Mucor mucedo, Saccharomyces cerevisiae and bacteria (Bacillus subtilis isolated from food microbiota. There were also, used microbial strains isolated from different pathological products: wound secretions (Staphylococcus aureus, throat swab (Streptococcus pyogenes, urine (Escherichia coli and oral mucosa (Candida albicans. The antimicrobial potential of used extracts is highlighted depending on the type of the vegetal tissue (leaves, roots, bulbs and the nature of the solvent used for extraction. Extracts used in these experiments are recommended to use in food industry to preserve the stability and to improve the organoleptic quality of products.

  19. Fission Research at IRMM

    Directory of Open Access Journals (Sweden)

    Al-Adili A.

    2010-03-01

    Full Text Available Fission Research at JRC-IRMM has a longstanding tradition. The present paper is discussing recent investigations of fission fragment properties of 238 U(n,f, 234 U(n,f, prompt neutron emission in fission of 252 Cf(SF as well as the prompt fission neutron spectrum of 235 U(n,f and is presenting the most important results.

  20. Impact of corticosterone treatment on spontaneous seizure frequency and epileptiform activity in mice with chronic epilepsy.

    Directory of Open Access Journals (Sweden)

    Olagide W Castro

    Full Text Available Stress is the most commonly reported precipitating factor for seizures in patients with epilepsy. Despite compelling anecdotal evidence for stress-induced seizures, animal models of the phenomena are sparse and possible mechanisms are unclear. Here, we tested the hypothesis that increased levels of the stress-associated hormone corticosterone (CORT would increase epileptiform activity and spontaneous seizure frequency in mice rendered epileptic following pilocarpine-induced status epilepticus. We monitored video-EEG activity in pilocarpine-treated mice 24/7 for a period of four or more weeks, during which animals were serially treated with CORT or vehicle. CORT increased the frequency and duration of epileptiform events within the first 24 hours of treatment, and this effect persisted for up to two weeks following termination of CORT injections. Interestingly, vehicle injection produced a transient spike in CORT levels - presumably due to the stress of injection - and a modest but significant increase in epileptiform activity. Neither CORT nor vehicle treatment significantly altered seizure frequency; although a small subset of animals did appear responsive. Taken together, our findings indicate that treatment of epileptic animals with exogenous CORT designed to mimic chronic stress can induce a persistent increase in interictal epileptiform activity.

  1. Spontaneous Activity Patterns in Primary Visual Cortex Predispose to Visual Hallucinations.

    Science.gov (United States)

    Pajani, Auréliane; Kok, Peter; Kouider, Sid; de Lange, Floris P

    2015-09-16

    According to theoretical frameworks casting perception as inference, vision results from the integration of bottom-up visual input with top-down expectations. Under conditions of strongly degraded sensory input, this may occasionally result in false perceptions in the absence of a sensory signal, also termed "hallucinations." Here, we investigated whether spontaneous prestimulus activity patterns in sensory circuits, which may embody a participant's prior expectations, predispose the observer toward false perceptions. Specifically, we used fMRI to investigate whether the representational content of prestimulus activity in early visual cortex is linked to subsequent perception during a challenging detection task. Human participants were asked to detect oriented gratings of a particular orientation that were embedded in noise. We found two characteristics of prestimulus activity that predisposed participants to hallucinations: overall lower prestimulus activity and a bias in the prestimulus activity patterns toward the to-be-detected (expected) grating. These results suggest that perceptual hallucinations may be due to an imprecise and biased state of sensory circuits preceding sensory evidence collection. When sensory stimulation is strongly degraded, we occasionally misperceive a stimulus when only noise is present: a perceptual hallucination. Using fMRI in healthy participants, we investigated whether the state of early visual cortex preceding stimulus onset predisposes an observer to hallucinations. We found two characteristics of prestimulus activity that predisposed participants to hallucinations: overall lower prestimulus activity and a bias in the prestimulus activity patterns toward the expected grating. These results suggest that perceptual hallucinations are due to an imprecise and biased state of sensory circuits preceding sensation. Copyright © 2015 the authors 0270-6474/15/3512947-07$15.00/0.

  2. A method to measure prompt fission neutron spectrum using gamma multiplicity tagging

    Energy Technology Data Exchange (ETDEWEB)

    Blain, E., E-mail: blaine2@rpi.edu; Daskalakis, A.; Block, R.C.; Barry, D.; Danon, Y.

    2016-01-01

    In order to improve on current prompt fission neutron spectrum measurements, a gamma multiplicity tagging method was developed at the Rensselaer Polytechnic Institute Gearttner Linear Accelerator Center. This method involves using a coincidence requirement on an array of BaF{sub 2} gamma detectors to determine the timing of a fission event. This allows for much larger fission samples to be used due to the higher penetrability of gammas compared to fission fragments. Additionally, since the method relies on gammas as opposed to fission fragments, the effects of the low level discriminator, used in fission chambers to eliminate alpha events, are not seen. A {sup 252}Cf fission chamber was constructed in order to determine the viability of this method as well as the efficiency when compared to a fission chamber. The implemented multiple gamma tagging method was found to accurately reproduce the prompt fission neutron spectrum for the spontaneous fission of {sup 252}Cf and to detect 30% of fission events. - Highlights: • A method measuring prompt fission neutron spectrum using gamma rays was proposed. • The method tags fission as reliably as a fission chamber and with better timing. • The gamma tag method shows good agreement with existing {sup 252}Cf data and models. • This eliminates the need of a fission chamber and allows larger samples to be measured.

  3. The epileptic human hippocampal cornu ammonis 2 region generates spontaneous interictal-like activity in vitro.

    Science.gov (United States)

    Wittner, Lucia; Huberfeld, Gilles; Clémenceau, Stéphane; Eross, Loránd; Dezamis, Edouard; Entz, László; Ulbert, István; Baulac, Michel; Freund, Tamás F; Maglóczky, Zsófia; Miles, Richard

    2009-11-01

    The dentate gyrus, the cornu ammonis 2 region and the subiculum of the human hippocampal formation are resistant to the cell loss associated with temporal lobe epilepsy. The subiculum, but not the dentate gyrus, generates interictal-like activity in tissue slices from epileptic patients. In this study, we asked whether a similar population activity is generated in the cornu ammonis 2 region and examined the electrophysiological and neuroanatomical characteristics of human epileptic cornu ammonis 2 neurons that may be involved. Hippocampal slices were prepared from postoperative temporal lobe tissue derived from epileptic patients. Field potentials and multi-unit activity were recorded in vitro using multiple extracellular microelectrodes. Pyramidal cells were characterized in intra-cellular records and were filled with biocytin for subsequent anatomy. Fluorescent immunostaining was made on fixed tissue against the chloride-cation cotransporters sodium-potassium-chloride cotransporter-1 and potassium-chloride cotransporter-2. Light and electron microscopy were used to examine the parvalbumin-positive perisomatic inhibitory network. In 15 of 20 slices, the hippocampal cornu ammonis 2 region generated a spontaneous interictal-like activity, independently of population events in the subiculum. Most cornu ammonis 2 pyramidal cells fired spontaneously. All cells fired single action potentials and burst firing was evoked in three cells. Spontaneous excitatory postsynaptic potentials were recorded in all cells, but hyperpolarizing inhibitory postsynaptic potentials were detected in only 27% of the cells. Two-thirds of cornu ammonis 2 neurons showed depolarizing responses during interictal-like events, while the others were inhibited, according to the current sink in the cell body layer. Two biocytin-filled cells both showed a pyramidal-like morphology with axons projecting to the cornu ammonis 2 and cornu ammonis 3 regions. Expression of sodium

  4. Drug-induced modification of the system properties associated with spontaneous human electroencephalographic activity

    Science.gov (United States)

    Liley, David T.; Cadusch, Peter J.; Gray, Marcus; Nathan, Pradeep J.

    2003-11-01

    The benzodiazepine (BZ) class of minor tranquilizers are important modulators of the γ-amino butyric acid (GABAA)/BZ receptor complex that are well known to affect the spectral properties of spontaneous electroencephalographic activity. While it is experimentally well established that the BZs reduce total alpha band (8 13 Hz) power and increase total beta band (13 30 Hz) power, it is unclear what the physiological basis for this effect is. Based on a detailed theory of cortical electrorhythmogenesis it is conjectured that such an effect is explicable in terms of the modulation of GABAergic neurotransmission within locally connected populations of excitatory and inhibitory cortical neurons. Motivated by this theory, fixed order autoregressive moving average (ARMA) models were fitted to spontaneous eyes-closed electroencephalograms recorded from subjects before and approximately 2 h after the oral administration of a single 1 mg dose of the BZ alprazolam. Subsequent pole-zero analysis revealed that BZs significantly transform the dominant system pole such that its frequency and damping increase. Comparisons of ARMA derived power spectra with fast Fourier transform derived spectra indicate an enhanced ability to identify benzodiazepine induced electroencephalographic changes. This experimental result is in accord with the theoretical predictions implying that alprazolam enhances inhibition acting on inhibitory neurons more than inhibition acting on excitatory neurons. Further such a result is consistent with reported cortical neuronal distributions of the various GABAA receptor pharmacological subtypes. Therefore physiologically specified fixed order ARMA modeling is expected to become an important tool for the systematic investigation and modeling of a wide range of cortically acting compounds.

  5. Cellular Origin of Spontaneous Ganglion Cell Spike Activity in Animal Models of Retinitis Pigmentosa

    Directory of Open Access Journals (Sweden)

    David J. Margolis

    2011-01-01

    Full Text Available Here we review evidence that loss of photoreceptors due to degenerative retinal disease causes an increase in the rate of spontaneous ganglion spike discharge. Information about persistent spike activity is important since it is expected to add noise to the communication between the eye and the brain and thus impact the design and effective use of retinal prosthetics for restoring visual function in patients blinded by disease. Patch-clamp recordings from identified types of ON and OFF retinal ganglion cells in the adult (36–210 d old rd1 mouse show that the ongoing oscillatory spike activity in both cell types is driven by strong rhythmic synaptic input from presynaptic neurons that is blocked by CNQX. The recurrent synaptic activity may arise in a negative feedback loop between a bipolar cell and an amacrine cell that exhibits resonant behavior and oscillations in membrane potential when the normal balance between excitation and inhibition is disrupted by the absence of photoreceptor input.

  6. Electrophysiological study in the infraorbital nerve of the rat: Spontaneous and evoked activity

    Energy Technology Data Exchange (ETDEWEB)

    AlbarracIn, A L [Catedra de Neurociencias, Facultad de Medicina, Universidad Nacional de Tucuman, Av. Roca 2200, PC 4000 (Argentina); Farfan, F D [Departamento de BioingenierIa, FACET, Universidad Nacional de Tucuman, INSIBIO - CONICET, CC 327, PC 4000 (Argentina); Felice, C J [Departamento de BioingenierIa, FACET, Universidad Nacional de Tucuman, INSIBIO - CONICET, CC 327, PC 4000 (Argentina)

    2007-11-15

    In this work we present some studies in the afferent nerve of the rat vibrissae. Studies on spontaneous activity (SA) in this sensorial system are of long data. Nevertheless, SA recordings in the nerve of a single vibrissa have not been made until present. In this work, we use an algorithm based on signal decomposition with Continuous Wavelet Transform (CWT) to analyse the discharges of two nerves. The action potentials of both nerves were detected and the firing rates were calculated. These results suggest that the firing rate of one vibrissa innervation is low considering that this nerve contains hundred of fibers. In addition, we present preliminary studies suggesting important effects of the hair shaft length in the afferent discharge during the vibrissae movements. The experiments consisted in recording the nerve activity after the vibrissae were sectioned at two different levels. The results showed important differences in the signal energy contents. It suggests that the hair shaft length would produce a differential activation of the mechanoreceptors located in the vibrissae follicle.

  7. Hypotensive and Angiotensin-Converting Enzyme Inhibitory Activities of Eisenia fetida Extract in Spontaneously Hypertensive Rats

    Directory of Open Access Journals (Sweden)

    Shumei Mao

    2015-01-01

    Full Text Available Objectives. This study aimed to investigate the antihypertensive effects of an Eisenia fetida extract (EFE and its possible mechanisms in spontaneously hypertensive rats (SHR rats. Methods. Sixteen-week-old SHR rats and Wistar-Kyoto rats (WKY rats were used in this study. Rats were, respectively, given EFE (EFE group, captopril (captopril group, or phosphate-buffered saline (PBS (normal control group and SHR group for 4 weeks. ACE inhibitory activity of EFE in vitro was determined. The systolic blood pressure (SBP and diastolic blood pressure (DBP were measured using a Rat Tail-Cuff Blood Pressure System. Levels of angiotensin II (Ang II, aldosterone (Ald, and 6-keto-prostaglandin F1 alpha (6-keto-PGF1α in plasma were determined by radioimmunoassay, and serum nitric oxide (NO concentration was measured by Griess reagent systems. Results. EFE had marked ACE inhibitory activity in vitro (IC50 = 2.5 mg/mL. After the 4-week drug management, SHR rats in EFE group and in captopril group had lower SBP and DBP, lower levels of Ang II and Ald, and higher levels of 6-keto-PGF1α and NO than the SHR rats in SHR group. Conclusion. These results indicate that EFE has hypotensive effects in SHR rats and its effects might be associated with its ACE inhibitory activity.

  8. Coincident measurements of prompt fission γ rays and fission fragments at DANCE

    Science.gov (United States)

    Walker, C. L.; Baramsai, B.; Jandel, M.; Rusev, G.; Couture, A.; Mosby, S.; Ullmann, J.; Kawano, T.; Stetcu, I.; Talou, P.

    2015-10-01

    Modern statistical approaches to modeling fission involve the calculation of not only average quantities but also fully correlated distributions of all fission products. Applications such as those involving the detection of special nuclear materials also rely on fully correlated data of fission products. Experimental measurements of correlated data are thus critical to the validation of theory and the development of important applications. The goal of this experiment was to measure properties of prompt fission gamma-ray emission as a function of fission fragments' total kinetic energy in the spontaneous fission of 252Cf. The measurement was carried out at the Detector for Advanced Neutron Capture Experiments (DANCE), a 4 π γ-ray calorimeter. A prototype design consisting of two silicon detectors was installed in the center of DANCE, allowing simultaneous measurement of fission fragments and γ rays. Effort has been taken to simulate fragment kinetic energy losses as well as γ-ray attenuation in DANCE using such tools as GEANT4 and SRIM. Theoretical predictions generated by the code CGMF were also incorporated as input for these simulations. Results from the experiment and simulations will be presented, along with plans for future measurements.

  9. Progress in fission product nuclear data

    International Nuclear Information System (INIS)

    Lammer, G.

    1975-01-01

    This is the first issue of a report series on Fission Product Nuclear Data (FPND), published every six months by the Nuclear Data Section (NDS) of the International Atomic Energy Agency (IAEA). Its purpose is to inform scientists working on FPND, or using such data, about all activities in this field which are planned, ongoing, or have recently been completed. The types of activities being included in this report are measurements, compilations and evaluations of: fission product yields; neutron cross-section data of fission products; data related to β-, γ-decay of fission products; delayed neutron data; and fission product decay-heat. The present issue includes contributions which were received by NDS before 1 November 1975

  10. Expression and activity of matrix metalloproteinases in the uterus of bitches after spontaneous and induced abortion.

    Science.gov (United States)

    Kanca, H; Walter, I; Miller, I; Schäfer-Somi, S; Izgur, H; Aslan, S

    2011-04-01

    Aim of this study was to determine the intrauterine activity of matrix metalloproteinases (MMP)-2 and -9 after cessation of the local effect of progesterone. For this purpose, pregnancy was terminated in 10 bitches at mid-gestation with the progesterone receptor antagonist aglepristone (10 mg/kg body weight, sc, Alizine®; Virbac, France) at two subsequent days (group IRA = induced resorption/abortion). The IRA group was divided into two subgroups (Group I, n = 5, days 25-35 of pregnancy; group II, n = 5, days 36-45). Five further bitches were introduced with beginning abortion (group SRA = spontaneous resorption/abortion). Seven healthy bitches between day 25 and 45 of gestation served as controls. After ovariohysterectomy at the end of abortion and between days 25 and 45 of gestation, respectively, the distribution and activity of collagenases were investigated by immunohistochemistry and gelatin zymography. At placental sites, MMP-2 activity in the endometrium was significantly lower in IRA groups than in the SRA group (33.7 ± 11.8% and 39.3 ± 5.4% vs 52.2 ± 10.2%, p < 0.05); however, MMP-2 expression was lowest in the control group (control: 21.4 ± 6.3%; p < 0.01) and similarly in the myometrium (controls: 13.1 ± 2.5%; p < 0.05). MMP-9 activity was also lower in the endometrium and myometrium of the control group in comparison to SRA and IRA groups (11.8 ± 3.2%; p < 0.01 and 28.4 ± 32.8%; p < 0.05). At interplacental sites, the amount of active collagenases in the myometrium was significantly lower in the control group. It is concluded that the blockade of the biological progesterone effect was associated with an increase in activity of both collagenases. © 2010 Blackwell Verlag GmbH.

  11. Endogenous cholinergic tone modulates spontaneous network level neuronal activity in primary cortical cultures grown on multi-electrode arrays

    OpenAIRE

    Hammond, Mark W; Xydas, Dimitris; Downes, Julia H; Bucci, Giovanna; Becerra, Victor; Warwick, Kevin; Constanti, Andrew; Nasuto, Slawomir J; Whalley, Benjamin J

    2013-01-01

    Background\\ud Cortical cultures grown long-term on multi-electrode arrays (MEAs) are frequently and extensively used as models of cortical networks in studies of neuronal firing activity, neuropharmacology, toxicology and mechanisms underlying synaptic plasticity. However, in contrast to the predominantly asynchronous neuronal firing activity exhibited by intact cortex, electrophysiological activity of mature cortical cultures is dominated by spontaneous epileptiform-like global burst events ...

  12. Abnormal Spontaneous Brain Activity in Patients With Anisometropic Amblyopia Using Resting-State Functional Magnetic Resonance Imaging.

    Science.gov (United States)

    Tang, Angcang; Chen, Taolin; Zhang, Junran; Gong, Qiyong; Liu, Longqian

    2017-09-01

    To explore the abnormality of spontaneous activity in patients with anisometropic amblyopia under resting-state functional magnetic resonance imaging (Rs-fMRI). Twenty-four participants were split into two groups. The anisometropic amblyopia group had 10 patients, all of whom had anisometropic amblyopia of the right eye, and the control group had 14 healthy subjects. All participants underwent Rs-fMRI scanning. Measurement of amplitude of low frequency fluctuations of the brain, which is a measure of the amplitudes of spontaneous brain activity, was used to investigate brain changes between the anisometropic amblyopia and control groups. Compared with an age- and gender-matched control group, the anisometropic amblyopia group showed increased amplitude of low frequency fluctuations of spontaneous brain activity in the left superior temporal gyrus, the left inferior parietal lobe, the left pons, and the right inferior semi-lunar lobe. The anisometropic amblyopia group also showed decreased amplitude of low frequency fluctuations in the bilateral medial frontal gyrus. This study demonstrated abnormal spontaneous brain activities in patients with anisometropic amblyopia under Rs-fMRI, and these abnormalities might contribute to the neuropathological mechanisms of anisometropic amblyopia. [J Pediatr Ophthalmol Strabismus. 2017;54(5):303-310.]. Copyright 2017, SLACK Incorporated.

  13. Altered spontaneous brain activity in patients with acute spinal cord injury revealed by resting-state functional MRI.

    Directory of Open Access Journals (Sweden)

    Ling Zhu

    Full Text Available Previous neuroimaging studies have provided evidence of structural and functional reorganization of brain in patients with chronic spinal cord injury (SCI. However, it remains unknown whether the spontaneous brain activity changes in acute SCI. In this study, we investigated intrinsic brain activity in acute SCI patients using a regional homogeneity (ReHo analysis based on resting-state functional magnetic resonance imaging.A total of 15 patients with acute SCI and 16 healthy controls participated in the study. The ReHo value was used to evaluate spontaneous brain activity, and voxel-wise comparisons of ReHo were performed to identify brain regions with altered spontaneous brain activity between groups. We also assessed the associations between ReHo and the clinical scores in brain regions showing changed spontaneous brain activity.Compared with the controls, the acute SCI patients showed decreased ReHo in the bilateral primary motor cortex/primary somatosensory cortex, bilateral supplementary motor area/dorsal lateral prefrontal cortex, right inferior frontal gyrus, bilateral dorsal anterior cingulate cortex and bilateral caudate; and increased ReHo in bilateral precuneus, the left inferior parietal lobe, the left brainstem/hippocampus, the left cingulate motor area, bilateral insula, bilateral thalamus and bilateral cerebellum. The average ReHo values of the left thalamus and right insula were negatively correlated with the international standards for the neurological classification of spinal cord injury motor scores.Our findings indicate that acute distant neuronal damage has an immediate impact on spontaneous brain activity. In acute SCI patients, the ReHo was prominently altered in brain regions involved in motor execution and cognitive control, default mode network, and which are associated with sensorimotor compensatory reorganization. Abnormal ReHo values in the left thalamus and right insula could serve as potential biomarkers for

  14. Pharmacological evidence of hypotensive activity of Marrubium vulgare and Foeniculum vulgare in spontaneously hypertensive rat.

    Science.gov (United States)

    El Bardai, S; Lyoussi, B; Wibo, M; Morel, N

    2001-05-01

    The hypotensive effects of the water extract of Marrubium vulgare L. and Foeniculum vulgare L. were investigated in spontaneously hypertensive rats (SHR) and in normotensive Wistar-Kyoto rats (WKY). Oral administration of Marrubium or Foeniculum extract lowered the systolic blood pressure of SHR but not of WKY. In SHR, Foeniculum but not Marrubium treatment increased water, sodium and potassium excretion. Ex vivo as well as in vitro, Marrubium extract inhibited the contractile responses of rat aorta to noradrenaline and to KCl (100 mM). Inhibition was greater in aorta from SHR compared to WKY and was not affected by the NO synthase inhibitor N-nitro-L-arginine. Vascular effects of Foeniculum extract were less pronounced than those of Marrubium and were blocked by N-nitro-L-arginine. These results indicate that hypotensive activity of Marrubium and Foeniculum extracts seems to be mediated through different pathways: Foeniculum appeared to act mainly as a diuretic and a natriuretic while Marrubium displayed vascular relaxant activity.

  15. Beyond blow-up in excitatory integrate and fire neuronal networks: Refractory period and spontaneous activity.

    Science.gov (United States)

    Cáceres, María J; Perthame, Benoît

    2014-06-07

    The Network Noisy Leaky Integrate and Fire equation is among the simplest model allowing for a self-consistent description of neural networks and gives a rule to determine the probability to find a neuron at the potential v. However, its mathematical structure is still poorly understood and, concerning its solutions, very few results are available. In the midst of them, a recent result shows blow-up in finite time for fully excitatory networks. The intuitive explanation is that each firing neuron induces a discharge of the others; thus increases the activity and consequently the discharge rate of the full network. In order to better understand the details of the phenomena and show that the equation is more complex and fruitful than expected, we analyze further the model. We extend the finite time blow-up result to the case when neurons, after firing, enter a refractory state for a given period of time. We also show that spontaneous activity may occur when, additionally, randomness is included on the firing potential VF in regimes where blow-up occurs for a fixed value of VF. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Fission properties of superheavy nuclei for r -process calculations

    Science.gov (United States)

    Giuliani, Samuel A.; Martínez-Pinedo, Gabriel; Robledo, Luis M.

    2018-03-01

    We computed a new set of static fission properties suited for r -process calculations. The potential energy surfaces and collective inertias of 3640 nuclei in the superheavy region are obtained from self-consistent mean-field calculations using the Barcelona-Catania-Paris-Madrid energy density functional. The fission path is computed as a function of the quadrupole moment by minimizing the potential energy and exploring octupole and hexadecapole deformations. The spontaneous fission lifetimes are evaluated employing different schemes for the collective inertias and vibrational energy corrections. This allows us to explore the sensitivity of the lifetimes to those quantities together with the collective ground-state energy along the superheavy landscape. We computed neutron-induced stellar reaction rates relevant for r -process nucleosynthesis using the Hauser-Feshbach statistical approach and study the impact of collective inertias. The competition between different reaction channels including neutron-induced rates, spontaneous fission, and α decay is discussed for typical r -process conditions.

  17. Physiological reactivity to spontaneously occurring seizure activity in dogs with epilepsy and their carers.

    Science.gov (United States)

    Packer, R M A; Volk, H A; Fowkes, R C

    2017-08-01

    There is a complex bidirectional relationship between stress and epilepsy. Stressful stimuli and subsequent cortisol release act as a trigger for seizure activity in some individuals with epilepsy, and seizure activity itself may act as a stressor to the affected individual. Epilepsy is the most common chronic neurological condition in domestic dogs and requires chronic management by their human carers, impacting upon the quality of life of both dog and carer. Seizures occur unpredictably and may be stressful for carers to witness and manage. In the present study we investigated the role of seizure activity as a stressor, measuring the effect of spontaneously occurring seizure activity in dogs with epilepsy upon their own cortisol levels and that of their carers. Furthermore, we tested whether individual differences in HPA reactivity were associated with owner personality characteristics and the quality of the dog-carer relationship. Saliva samples were obtained from sixteen dog-carer dyads in the home setting 20 and 40minute post-seizure, and at time-matched points on the following (non-seizure) day. Significant differences in cortisol levels were found in dogs at 40minute post-seizure (265.1% increase), and at 20minute post-seizure in their carers (40.5% increase). No associations were found between cortisol reactivity and the strength of the dog-carer bond. Carers with higher neuroticism scores exhibited higher cortisol levels at both post-seizure sampling points. As there was a gender bias in the carer sample (15/16 were female), and there are known sex differences in cortisol reactivity in response to psychological stress, the conclusions of this study may be limited to female carers. These findings are the first to objectively demonstrate the acutely stressful effects of seizures in dogs with epilepsy and their carers. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Prompt fissionγ-ray characteristics from neutron-induced fission on 239Pu and the time-dependence of prompt-γray emission

    Directory of Open Access Journals (Sweden)

    Gatera Angélique

    2018-01-01

    The latest results for PFG characteristics from the reaction 239Pu(nth,f will be presented, together with an analysis of PFGs emitted up to 200 ns after fission in the spontaneous fission of 252Cf as well as for thermal-neutron induced fission on 235U and 239Pu. The results are compared with calculations in the framework of the Hauser-Feshbach Monte Carlo code CGMF and FIFRELIN.

  19. Generalized Energy-Dependent Q Values for Fission

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, R

    2010-03-31

    We extend Madland's parameterization of the energy release in fission to obtain the dependence of the fission Q value for major and minor actinides on the incident neutron energies in the range 0 {le} E{sub n} {le} 20 MeV. Our parameterization is based on the actinide evaluations recommended for the ENDF/B-VII.1 release. This paper describes the calculation of energydependent fission Q values based on the calculation of the prompt energy release in fission by Madland. This calculation was adopted for use in the LLNL ENDL database and then generalized to obtain the prompt fission energy release for all actinides. Here the calculation is further generalized to the total energy release in fission. There are several stages in a fission event, depending on the time scale. Neutrons and gammas may be emitted at any time during the fission event.While our discussion here is focussed on compound nucleus creation by an incident neutron, similar parameterizations could be obtained for incident gammas or spontaneous fission.

  20. The Wiring of Developing Sensory Circuits-From Patterned Spontaneous Activity to Synaptic Plasticity Mechanisms

    NARCIS (Netherlands)

    Leighton, Alexandra H; Lohmann, C.

    2016-01-01

    In order to accurately process incoming sensory stimuli, neurons must be organized into functional networks, with both genetic and environmental factors influencing the precise arrangement of connections between cells. Teasing apart the relative contributions of molecular guidance cues, spontaneous

  1. EXERCISE TRAINING IMPROVES CARDIOVASCULAR AUTONOMIC ACTIVITY AND ATTENUATES RENAL DAMAGE IN SPONTANEOUSLY HYPERTENSIVE RATS

    Directory of Open Access Journals (Sweden)

    Octávio Barbosa Neto

    2013-03-01

    Full Text Available Experiments were performed to determine the influence of exercise training by swimming on cardiovascular autonomic control and renal morphology in spontaneously hypertensive rats (SHR and Wystar-Kyoto (WKY rats. Sedentary normotensive (SN, trained normotensive (TN, sedentary hypertensive (SH, and trained hypertensive (TH rats were included in this study. Arterial pressure (AP, heart rate (HR, means of power spectral analysis of HR (HRV and systolic AP variability (SAPV were recorded in baseline conditions. Following, the HR baroreflex and autonomic tonus control were assessed. At the end, all animals were euthanized and their kidneys were excised to evaluate renal damage. Resting bradycardia was observed in TH and TN rats compared with their respective sedentary animals (p < 0.05. Exercise training attenuated AP in TH vs. SH (p < 0.001. The LF component of HRV and SAPV were lower in TH than SH (p < 0.05. The LF/HF relation was lower in TH than SH and SN (p < 0.05. TN and TH rats showed a sympathetic tonus reduction in comparison to SN and SH rats (p < 0.001. The TH presented an increased vagal tonus compared to SH (p < 0.05. Exercise training improved baroreflex control of HR in TH group versus SH (p < 0.05. The TH showed a lower number of sclerotic glomeruli compared to SH (p < 0.005. The exercise training decrease the glomerular indexes in TN and TH (p < 0.05. Further analysis showed a significant correlation between sympathetic nervous activity and AP levels (p < 0.05. A positive association was also found between sympathetic nervous activity and glomerular index (p < 0.05. Therefore, the exercise training reduces AP and attenuates renal damage. In addition, the attenuation of renal injury was associated with lower sympathetic activity. These findings strongly suggest that exercise training may be a therapeutic tool for improving structure and renal function in hypertensive individuals.

  2. Effects of taurine on resting-state fMRI activity in spontaneously hypertensive rats.

    Directory of Open Access Journals (Sweden)

    Vincent Chin-Hung Chen

    Full Text Available Attention deficit hyperactivity disorder (ADHD is a global behavior illness among children and adults. To investigate the effects of taurine on resting-state fMRI activity in ADHD, a spontaneously hypertensive rat (SHR animal model was adopted. Significantly decreased serum C-reactive protein (CRP was detected in rats of Wistar Kyoto (WKY high-taurine group and significantly decreased interleukin (IL-1β and CRP were detected in rats of SHR low-taurine and high-taurine groups. Moreover, significantly higher horizontal locomotion was detected in rats of WKY low-taurine and SHR low-taurine groups than in those of controls. In contrast, significantly lower horizontal locomotion was detected in rats of the SHR high-taurine group than in those of the SHR control group. Additionally, significantly lower functional connectivity (FC and mean amplitude of low-frequency fluctuation (mALFF in the bilateral hippocampus in rats of WKY high-taurine and SHR high-taurine groups was detected. Notably, the mALFF in rats of the SHR low-taurine and high-taurine groups was significantly lower than in those of the SHR control group. These findings suggest that the administration of a high-dose taurine probably improves hyperactive behavior in SHR rats by ameliorating the inflammatory cytokines and modulating brain functional signals in SHR rats.

  3. Electroacupuncture Delays Hypertension Development through Enhancing NO/NOS Activity in Spontaneously Hypertensive Rats

    Directory of Open Access Journals (Sweden)

    Hye Suk Hwang

    2011-01-01

    Full Text Available Using spontaneously hypertensive rats (SHR, this study investigated whether electroacupuncture (EA could reduce early stage hypertension by examining nitric oxide (NO levels in plasma and nitric oxide synthase (NOS levels in the mesenteric resistance artery. EA was applied to the acupuncture point Governor Vessel 20 (GV20 or to a non-acupuncture point in the tail twice weekly for 3 weeks under anesthesia. In conscious SHR and normotensive Wistar Kyoto (WKY rats, blood pressure was determined the day after EA treatment by the tail-cuff method. We measured plasma NO concentration, and evaluated endothelial NO syntheses (eNOS and neuronal NOS (nNOS protein expression in the mesenteric artery. Systolic blood pressure (SBP and diastolic blood pressure (DBP were lower after 3 weeks of GV20 treatment than EA at non-acupuncture point and no treatment control in SHR. nNOS expression by EA was significantly different between both WKY and no treatment SHR control, and EA at GV20 in SHR. eNOS expression was significantly high in EA at GV 20 compared with no treatment control. In conclusion, EA could attenuate the blood pressure elevation of SHR, along with enhancing NO/NOS activity in the mesenteric artery in SHR.

  4. Brain activity dynamics in human parietal regions during spontaneous switches in bistable perception.

    Science.gov (United States)

    Megumi, Fukuda; Bahrami, Bahador; Kanai, Ryota; Rees, Geraint

    2015-02-15

    The neural mechanisms underlying conscious visual perception have been extensively investigated using bistable perception paradigms. Previous functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) studies suggest that the right anterior superior parietal (r-aSPL) and the right posterior superior parietal lobule (r-pSPL) have opposite roles in triggering perceptual reversals. It has been proposed that these two areas are part of a hierarchical network whose dynamics determine perceptual switches. However, how these two parietal regions interact with each other and with the rest of the brain during bistable perception is not known. Here, we investigated such a model by recording brain activity using fMRI while participants viewed a bistable structure-from-motion stimulus. Using dynamic causal modeling (DCM), we found that resolving such perceptual ambiguity was specifically associated with reciprocal interactions between these parietal regions and V5/MT. Strikingly, the strength of bottom-up coupling between V5/MT to r-pSPL and from r-pSPL to r-aSPL predicted individual mean dominance duration. Our findings are consistent with a hierarchical predictive coding model of parietal involvement in bistable perception and suggest that visual information processing underlying spontaneous perceptual switches can be described as changes in connectivity strength between parietal and visual cortical regions. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  5. Effects of taurine on resting-state fMRI activity in spontaneously hypertensive rats

    Science.gov (United States)

    Chen, Vincent Chin-Hung; Hsu, Tsai-Ching; Chen, Li-Jeng; Chou, Hong-Chun

    2017-01-01

    Attention deficit hyperactivity disorder (ADHD) is a global behavior illness among children and adults. To investigate the effects of taurine on resting-state fMRI activity in ADHD, a spontaneously hypertensive rat (SHR) animal model was adopted. Significantly decreased serum C-reactive protein (CRP) was detected in rats of Wistar Kyoto (WKY) high-taurine group and significantly decreased interleukin (IL)-1β and CRP were detected in rats of SHR low-taurine and high-taurine groups. Moreover, significantly higher horizontal locomotion was detected in rats of WKY low-taurine and SHR low-taurine groups than in those of controls. In contrast, significantly lower horizontal locomotion was detected in rats of the SHR high-taurine group than in those of the SHR control group. Additionally, significantly lower functional connectivity (FC) and mean amplitude of low-frequency fluctuation (mALFF) in the bilateral hippocampus in rats of WKY high-taurine and SHR high-taurine groups was detected. Notably, the mALFF in rats of the SHR low-taurine and high-taurine groups was significantly lower than in those of the SHR control group. These findings suggest that the administration of a high-dose taurine probably improves hyperactive behavior in SHR rats by ameliorating the inflammatory cytokines and modulating brain functional signals in SHR rats. PMID:28700674

  6. Effects of taurine on resting-state fMRI activity in spontaneously hypertensive rats.

    Science.gov (United States)

    Chen, Vincent Chin-Hung; Hsu, Tsai-Ching; Chen, Li-Jeng; Chou, Hong-Chun; Weng, Jun-Cheng; Tzang, Bor-Show

    2017-01-01

    Attention deficit hyperactivity disorder (ADHD) is a global behavior illness among children and adults. To investigate the effects of taurine on resting-state fMRI activity in ADHD, a spontaneously hypertensive rat (SHR) animal model was adopted. Significantly decreased serum C-reactive protein (CRP) was detected in rats of Wistar Kyoto (WKY) high-taurine group and significantly decreased interleukin (IL)-1β and CRP were detected in rats of SHR low-taurine and high-taurine groups. Moreover, significantly higher horizontal locomotion was detected in rats of WKY low-taurine and SHR low-taurine groups than in those of controls. In contrast, significantly lower horizontal locomotion was detected in rats of the SHR high-taurine group than in those of the SHR control group. Additionally, significantly lower functional connectivity (FC) and mean amplitude of low-frequency fluctuation (mALFF) in the bilateral hippocampus in rats of WKY high-taurine and SHR high-taurine groups was detected. Notably, the mALFF in rats of the SHR low-taurine and high-taurine groups was significantly lower than in those of the SHR control group. These findings suggest that the administration of a high-dose taurine probably improves hyperactive behavior in SHR rats by ameliorating the inflammatory cytokines and modulating brain functional signals in SHR rats.

  7. Rupturing the hemi-fission intermediate in membrane fission under tension: Reaction coordinates, kinetic pathways, and free-energy barriers

    Science.gov (United States)

    Zhang, Guojie; Müller, Marcus

    2017-08-01

    Membrane fission is a fundamental process in cells, involved inter alia in endocytosis, intracellular trafficking, and virus infection. Its underlying molecular mechanism, however, is only incompletely understood. Recently, experiments and computer simulation studies have revealed that dynamin-mediated membrane fission is a two-step process that proceeds via a metastable hemi-fission intermediate (or wormlike micelle) formed by dynamin's constriction. Importantly, this hemi-fission intermediate is remarkably metastable, i.e., its subsequent rupture that completes the fission process does not occur spontaneously but requires additional, external effects, e.g., dynamin's (unknown) conformational changes or membrane tension. Using simulations of a coarse-grained, implicit-solvent model of lipid membranes, we investigate the molecular mechanism of rupturing the hemi-fission intermediate, such as its pathway, the concomitant transition states, and barriers, as well as the role of membrane tension. The membrane tension is controlled by the chemical potential of the lipids, and the free-energy landscape as a function of two reaction coordinates is obtained by grand canonical Wang-Landau sampling. Our results show that, in the course of rupturing, the hemi-fission intermediate undergoes a "thinning → local pinching → rupture/fission" pathway, with a bottle-neck-shaped cylindrical micelle as a transition state. Although an increase of membrane tension facilitates the fission process by reducing the corresponding free-energy barrier, for biologically relevant tensions, the free-energy barriers still significantly exceed the thermal energy scale kBT.

  8. Interactions between procedural learning and cocaine exposure alter spontaneous and cortically-evoked spike activity in the dorsal striatum

    Directory of Open Access Journals (Sweden)

    Janie eOndracek

    2010-12-01

    Full Text Available We have previously shown that cocaine enhances gene regulation in the sensorimotor striatum associated with procedural learning in a running-wheel paradigm. Here we assessed whether cocaine produces enduring modifications of learning-related changes in striatal neuron activity, using single-unit recordings in anesthetized rats 1 day after the wheel training. Spontaneous and cortically-evoked spike activity was compared between groups treated with cocaine or vehicle immediately prior to the running-wheel training or placement in a locked wheel (control conditions. We found that wheel training in vehicle-treated rats increased the average firing rate of spontaneously active neurons without changing the relative proportion of active to quiescent cells. In contrast, in rats trained under the influence of cocaine, the proportion of spontaneously firing to quiescent cells was significantly greater than in vehicle-treated, trained rats. However, this effect was associated with a lower average firing rate in these spontaneously active cells, suggesting that training under the influence of cocaine recruited additional low-firing cells. Measures of cortically-evoked activity revealed a second interaction between cocaine treatment and wheel training, namely, a cocaine-induced decrease in spike onset latency in control rats (locked wheel. This facilitatory effect of cocaine was abolished when rats trained in the running wheel during cocaine action. These findings highlight important interactions between cocaine and procedural learning, which act to modify population firing activity and the responsiveness of striatal neurons to excitatory inputs. Moreover, these effects were found 24 hours after the training and last drug exposure indicating that cocaine exposure during the learning phase triggers long-lasting changes in synaptic plasticity in the dorsal striatum. Such changes may contribute to the transition from recreational to habitual or compulsive drug

  9. Description of light charged particle emission in ternary fission

    International Nuclear Information System (INIS)

    Andreev, A. V.; Adamian, G. G.; Antonenko, N. V.; Kuklin, S. N.; Scheid, W.

    2010-01-01

    We consider the motion of three fragments starting from the scission point of ternary system. In the alpha-accompanied ternary fission the initial conditions are not the free parameters and determined by minimization of potential energy at scission point. In the trajectory calculations the angular distribution and mean value of the kinetic energy of the alpha-particles are well described in the spontaneous ternary fission of 252 Cf. In the Be- and C-accompanied ternary fission we found that the emission of the third particle occurs from one of the heavy fragments after their separation. (authors)

  10. Self-Organized Fission Control for Flocking System

    Directory of Open Access Journals (Sweden)

    Mingyong Liu

    2015-01-01

    Full Text Available This paper studies the self-organized fission control problem for flocking system. Motivated by the fission behavior of biological flocks, information coupling degree (ICD is firstly designed to represent the interaction intensity between individuals. Then, from the information transfer perspective, a “maximum-ICD” based pairwise interaction rule is proposed to realize the directional information propagation within the flock. Together with the “separation/alignment/cohesion” rules, a self-organized fission control algorithm is established that achieves the spontaneous splitting of flocking system under conflict external stimuli. Finally, numerical simulations are provided to demonstrate the effectiveness of the proposed algorithm.

  11. Learning to modulate one's own brain activity: The effect of spontaneous mental strategies

    Directory of Open Access Journals (Sweden)

    Silvia Erika Kober

    2013-10-01

    Full Text Available Using neurofeedback (NF, individuals can learn to modulate their own brain activity, in most cases electroencephalographic (EEG rhythms. Although a large body of literature reports positive effects of NF training on behavior and cognitive functions, there are hardly any reports on how participants can successfully learn to gain control over their own brain activity. About one third of people fail to gain significant control over their brain signals even after repeated training sessions. The reasons for this failure are still largely unknown. In this context, we investigated the effects of spontaneous mental strategies on NF performance. Twenty healthy participants performed either a SMR (sensorimotor rhythm, 12-15 Hz based or a Gamma (40-43 Hz based NF training over ten sessions. After the first and the last training session, they were asked to write down which mental strategy they have used for self-regulating their EEG. After the first session, all participants reported the use of various types of mental strategies such as visual strategies, concentration, or relaxation. After the last NF training session, four participants of the SMR group reported to employ no specific strategy. These four participants showed linear improvements in NF performance over the ten training sessions. In contrast, participants still reporting the use of specific mental strategies in the last NF session showed no changes in SMR based NF performance over the ten sessions. This effect could not be observed in the Gamma group. The Gamma group showed no prominent changes in Gamma power over the NF training sessions, regardless of the mental strategies used. These results indicate that successful SMR based NF performance is associated with implicit learning mechanisms. Participants stating vivid reports on strategies to control their SMR probably overload cognitive resources, which might be counterproductive in terms of increasing SMR power.

  12. Intermediate energy nuclear fission

    International Nuclear Information System (INIS)

    Hylten, G.

    1982-01-01

    Nuclear fission has been investigated with the double-kinetic-energy method using silicon surface barrier detectors. Fragment energy correlation measurements have been made for U, Th and Bi with bremsstrahlung of 600 MeV maximum energy. Distributions of kinetic energy as a function of fragment mass are presented. The results are compared with earlier photofission data and in the case of bismuth, with calculations based on the liquid drop model. The binary fission process in U, Yb, Tb, Ce, La, Sb, Ag and Y induced by 600 MeV protons has been investigated yielding fission cross sections, fragment kinetic energies, angular correlations and mass distributions. Fission-spallation competition calculations are used to deduce values of macroscopic fission barrier heights and nuclear level density parameter values at deformations corresponding to the saddle point shapes. We find macroscopic fission barriers lower than those predicted by macroscopic theories. No indication is found of the Businaro Gallone limit expected to occur somewhere in the mass range A = 100 to A = 140. For Ce and La asymmetric mass distributions similar to those in the actinide region are found. A method is described for the analysis of angular correlations between complementary fission products. The description is mainly concerned with fission induced by medium-energy protons but is applicable also to other projectiles and energies. It is shown that the momentum and excitation energy distributions of cascade residuals leading to fission can be extracted. (Author)

  13. Altered local spontaneous activity in frontal lobe epilepsy: a resting-state functional magnetic resonance imaging study.

    Science.gov (United States)

    Dong, Li; Li, Hechun; He, Zhongqiong; Jiang, Sisi; Klugah-Brown, Benjamin; Chen, Lin; Wang, Pu; Tan, Song; Luo, Cheng; Yao, Dezhong

    2016-11-01

    The purpose of this study was to investigate the local spatiotemporal consistency of spontaneous brain activity in patients with frontal lobe epilepsy (FLE). Eyes closed resting-state functional magnetic resonance imaging (fMRI) data were collected from 19 FLE patients and 19 age- and gender-matched healthy controls. A novel measure, named FOur-dimensional (spatiotemporal) Consistency of local neural Activities (FOCA) was used to assess the spatiotemporal consistency of local spontaneous activity (emphasizing both local temporal homogeneity and regional stability of brain activity states). Then, two-sample t test was performed to detect the FOCA differences between two groups. Partial correlations between the FOCA values and durations of epilepsy were further analyzed. Compared with controls, FLE patients demonstrated increased FOCA in distant brain regions including the frontal and parietal cortices, as well as the basal ganglia. The decreased FOCA was located in the temporal cortex, posterior default model regions, and cerebellum. In addition, the FOCA measure was linked to the duration of epilepsy in basal ganglia. Our study suggested that alterations of local spontaneous activity in frontoparietal cortex and basal ganglia was associated with the pathophysiology of FLE; and the abnormality in frontal and default model regions might account for the potential cognitive impairment in FLE. We also presumed that the FOCA measure had potential to provide important insights into understanding epilepsy such as FLE.

  14. GABA-A receptor antagonists increase firing, bursting and synchrony of spontaneous activity in neuronal networks grown on microelectrode arrays: a step towards chemical "fingerprinting"

    Science.gov (United States)

    Assessment of effects on spontaneous network activity in neurons grown on MEAs is a proposed method to screen chemicals for potential neurotoxicity. In addition, differential effects on network activity (chemical "fingerprints") could be used to classify chemical modes of action....

  15. AN INFLUENCE OF SPONTANEOUS MICROFLORA OF FERMENTED HORSEMEAT PRODUCTS ON THE FORMATION OF BIOLOGICALLY ACTIVE PEPTIDES

    Directory of Open Access Journals (Sweden)

    I. M. Chernukha

    2017-01-01

    Full Text Available At present, different methods are used to accumulate functional peptides in meat raw materials, including the use of spontaneous microflora during autolysis, the use of the microbial enzymes (the application of starter cultures and the use of the non-microbial enzymes (enzymes of animals and plant origin. Each method has its own specific characteristics of an impact on raw materials, which requires their detail study. This paper examines an effect of spontaneous microflora of fermented meat products from horsemeat on formation of biologically active peptides. Using the T-RFLP analysis, it was established that in air dried and uncooked smoked sausages produced with the use of the muscle tissue of horsemeat as a raw material, a significant proportion of microflora was presented by lactic acid microorganisms. The highest content of lactic acid microflora was observed in sample 1 (52.45 %, and the least in sample 3 (29.62 %. Sample 2 had the medium percent content of microflora compared to samples 1 and 3 — 38.82 %. It is necessary to note that about 25 % of microflora was unculturable; i.e., it had metabolic processes but did not grow on culture media. In the samples, the representatives of Actinobacteria and Pseudomonadales were found. Pathogenic and conditionally pathogenic microflora was not detected. Not only quantitative but also qualitative changes were observed in the studied samples. For example, in samples 1 and 2, the fractions of amilo-1,6-glucosidase, fast-type muscle myosin-binding-protein C; glucose-6-phosphate isomerase; fast skeletal muscle troponin I, phosphoglycerate kinase, pyruvate kinase and skeletal muscle actin were found, which were absent or reduced in sample 3. Therefore, in the studied product, good preservation of the main spectra of muscle proteins was observed, and the identified fractions, apparently, can be sources of new functional peptides. Not only quantitative but also qualitative changes were observed in the

  16. Population calcium imaging of spontaneous respiratory and novel motor activity in the facial nucleus and ventral brainstem in newborn mice

    DEFF Research Database (Denmark)

    Persson, Karin; Rekling, Jens C

    2011-01-01

    The brainstem contains rhythm and pattern forming circuits, which drive cranial and spinal motor pools to produce respiratory and other motor patterns. Here we used calcium imaging combined with nerve recordings in newborn mice to reveal spontaneous population activity in the ventral brainstem...... in lateral and medial subnuclei. Whole-cell recordings from facial motoneurons showed weak respiratory drives, and electrical field potential recordings confirmed respiratory drive to particularly the dorsal and lateral subnuclei. Putative facial premotoneurons showed respiratory-related calcium signals...

  17. Fission Spectrum Related Uncertainties

    Energy Technology Data Exchange (ETDEWEB)

    G. Aliberti; I. Kodeli; G. Palmiotti; M. Salvatores

    2007-10-01

    The paper presents a preliminary uncertainty analysis related to potential uncertainties on the fission spectrum data. Consistent results are shown for a reference fast reactor design configuration and for experimental thermal configurations. However the results obtained indicate the need for further analysis, in particular in terms of fission spectrum uncertainty data assessment.

  18. The nuclear fission

    International Nuclear Information System (INIS)

    Fiorentino, J.

    1983-01-01

    The nuclear fission process considering initially the formation of compound nucleus and finishing with radioactive decay of fission products is studied. The process is divided in three parts which consist of the events associated to the nucleus of intermediate transitional state, the scission configuration, and the phenomenum of post scission. (M.C.K.) [pt

  19. Contribution to statistics in fission track counting

    International Nuclear Information System (INIS)

    Bigazzi, G.; Bonadonna, F.; Neto, J.C.H.

    1986-01-01

    In order to test the new statistical model proposed in two papers by McGee, Johnson and Naeser for calculating the standard error in fission track dating, spontaneous and induced track counts from external detector method-EDM-or similar were simulated by random numbers, assuming that, for a given uranium content, fission tracks were spatially distributed according to Poisson distributions. By the results of such a simulation it can be concluded that: (1) In EDM, (1/nsub(s)+1/nsub(I)sup(1/2) represents a reliable evaluation of the relative standard error of rhosub(s)/rhosub(I)-ratio of spontaneous to induced track densities in a sample in which nsub(s) spontaneous and nsub(I) induced tracks were counted. (2) The new model confirms the validity of the above conclusion, by applying it to the spontaneous and induced track counts whose relative standard deviations of the means were evaluated by normal sampling statistics. Population method-PM-data were also simulated; (σ-bar' 2 sub(s)+σ-bar' 2 sub(I))sup(1/2), where σ-bar'sub(s) and σ-bar'sub(I) are the above relative standard deviations of the mean, offers a reliable evaluations of the uncertainty of rhosub(s)/rhosub(I) ratio for the simple cases analyzed in the present work. (author)

  20. Correlated fission data measurements with DANCE and NEUANCE

    Science.gov (United States)

    Jandel, M.; Baramsai, B.; Bredeweg, T. A.; Couture, A.; Favalli, A.; Hayes, A. C.; Ianakiev, K. D.; Iliev, M. L.; Kawano, T.; Mosby, S.; Rusev, G.; Stetcu, I.; Talou, P.; Ullmann, J. L.; Vieira, D. J.; Walker, C. L.; Wilhelmy, J. B.

    2018-02-01

    To enhance the capabilities of the DANCE array, a new detector array NEUANCE was developed to enable simultaneous measurements of prompt fission neutrons and γ rays. NEUANCE was designed and constructed using 21 stilbene organic scintillator crystals. It was installed in the central cavity of the DANCE array. Signals from the 160 BaF2 detectors of DANCE and the 21 detectors of NEUANCE were merged into a newly designed high-density high-throughput data acquisition system. The excellent pulse shape discrimination properties of stilbene enabled detection of neutrons with energy thresholds as low as 30-40 keVee. A fission reaction tagging method was developed using a NEUANCE γ-ray or neutron signal. The probability of detecting a neutron from the spontaneous fission of 252Cf using NEUANCE is ∼47%. New correlated data for prompt fission neutrons and prompt fission γ rays were obtained for 252Cf using this high detection efficiency experimental setup. Average properties of prompt fission neutron emission as a function of prompt fission γ-ray quantities were also obtained, suggesting that neutron and γ-ray emission in fission are correlated.

  1. Does low protein concentration of tissue-type plasminogen activator predict a low risk of spontaneous deep vein thrombosis?

    DEFF Research Database (Denmark)

    Gram, J; Sidelmann, Johannes Jakobsen; Jespersen, J

    1995-01-01

    Many reports have demonstrated an abnormal fibrinolysis in a subset of patients with deep vein thrombosis. We have studied systemic global fibrinolytic activity and protein concentrations of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1) in plasma of 25...... young patients with a previous instance of spontaneous deep vein thrombosis documented by phlebography and in 50 healthy controls. The two populations were comparable with respect to a number of base-line variables (age, height, weight, etc.), while the patients had significantly lower fibrinolytic...

  2. Fission 2009 4. International Workshop on Nuclear Fission and Fission Product Spectroscopy - Compilation of slides

    International Nuclear Information System (INIS)

    2009-01-01

    This conference is dedicated to the last achievements in experimental and theoretical aspects of the nuclear fission process. The topics include: mass, charge and energy distribution, dynamical aspect of the fission process, nuclear data evaluation, quasi-fission and fission lifetime in super heavy elements, fission fragment spectroscopy, cross-section and fission barrier, and neutron and gamma emission. This document gathers the program of the conference and the slides of the presentations

  3. Activity-dependent plasticity in the isolated embryonic avian brainstem following manipulations of rhythmic spontaneous neural activity.

    Science.gov (United States)

    Vincen-Brown, Michael A; Revill, Ann L; Pilarski, Jason Q

    2016-07-15

    When rhythmic spontaneous neural activity (rSNA) first appears in the embryonic chick brainstem and cranial nerve motor axons it is principally driven by nicotinic neurotransmission (NT). At this early age, the nicotinic acetylcholine receptor (nAChR) agonist nicotine is known to critically disrupt rSNA at low concentrations (0.1-0.5μM), which are levels that mimic the blood plasma levels of a fetus following maternal cigarette smoking. Thus, we quantified the effect of persistent exposure to exogenous nicotine on rSNA using an in vitro developmental model. We found that rSNA was eliminated by continuous bath application of exogenous nicotine, but rSNA recovered activity within 6-12h despite the persistent activation and desensitization of nAChRs. During the recovery period rSNA was critically driven by chloride-mediated membrane depolarization instead of nicotinic NT. To test whether this observed compensation was unique to the antagonism of nicotinic NT or whether the loss of spiking behavior also played a role, we eliminated rSNA by lowering overall excitatory drive with a low [K(+)]o superfusate. In this context, rSNA again recovered, although the recovery time was much quicker, and exhibited a lower frequency, higher duration, and an increase in the number of bursts per episode when compared to control embryos. Importantly, we show that the main compensatory response to lower overall excitatory drive, similar to nicotinergic block, is a result of potentiated chloride mediated membrane depolarization. These results support increasing evidence that early neural circuits sense spiking behavior to maintain primordial bioelectric rhythms. Understanding the nature of developmental plasticity in the nervous system, especially versions that preserve rhythmic behaviors following clinically meaningful environmental stimuli, both normal and pathological, will require similar studies to determine the consequences of feedback compensation at more mature chronological ages

  4. Central command does not suppress baroreflex control of cardiac sympathetic nerve activity at the onset of spontaneous motor activity in the decerebrate cat.

    Science.gov (United States)

    Matsukawa, Kanji; Ishii, Kei; Asahara, Ryota; Idesako, Mitsuhiro

    2016-10-01

    Our laboratory has reported that central command blunts the sensitivity of the aortic baroreceptor-heart rate (HR) reflex at the onset of voluntary static exercise in animals. We have examined whether baroreflex control of cardiac sympathetic nerve activity (CSNA) and/or cardiovagal baroreflex sensitivity are altered at the onset of spontaneously occurring motor behavior, which was monitored with tibial nerve activity in paralyzed, decerebrate cats. CSNA exhibited a peak increase (126 ± 17%) immediately after exercise onset, followed by increases in HR and mean arterial pressure (MAP). With development of the pressor response, CSNA and HR decreased near baseline, although spontaneous motor activity was not terminated. Atropine methyl nitrate (0.1-0.2 mg/kg iv) with little central influence delayed the initial increase in HR but did not alter the response magnitudes of HR and CSNA, while atropine augmented the pressor response. The baroreflex-induced decreases in CSNA and HR elicited by brief occlusion of the abdominal aorta were challenged at the onset of spontaneous motor activity. Spontaneous motor activity blunted the baroreflex reduction in HR by aortic occlusion but did not alter the baroreflex inhibition of CSNA. Similarly, atropine abolished the baroreflex reduction in HR but did not influence the baroreflex inhibition of CSNA. Thus it is likely that central command increases CSNA and decreases cardiac vagal outflow at the onset of spontaneous motor activity while preserving baroreflex control of CSNA. Accordingly, central command must attenuate cardiovagal baroreflex sensitivity against an excess rise in MAP as estimated from the effect of muscarinic blockade. Copyright © 2016 the American Physiological Society.

  5. Combining task-evoked and spontaneous activity to improve pre-operative brain mapping with fMRI

    Science.gov (United States)

    Fox, Michael D.; Qian, Tianyi; Madsen, Joseph R.; Wang, Danhong; Li, Meiling; Ge, Manling; Zuo, Huan-cong; Groppe, David M.; Mehta, Ashesh D.; Hong, Bo; Liu, Hesheng

    2016-01-01

    Noninvasive localization of brain function is used to understand and treat neurological disease, exemplified by pre-operative fMRI mapping prior to neurosurgical intervention. The principal approach for generating these maps relies on brain responses evoked by a task and, despite known limitations, has dominated clinical practice for over 20 years. Recently, pre-operative fMRI mapping based on correlations in spontaneous brain activity has been demonstrated, however this approach has its own limitations and has not seen widespread clinical use. Here we show that spontaneous and task-based mapping can be performed together using the same pre-operative fMRI data, provide complimentary information relevant for functional localization, and can be combined to improve identification of eloquent motor cortex. Accuracy, sensitivity, and specificity of our approach are quantified through comparison with electrical cortical stimulation mapping in eight patients with intractable epilepsy. Broad applicability and reproducibility of our approach is demonstrated through prospective replication in an independent dataset of six patients from a different center. In both cohorts and every individual patient, we see a significant improvement in signal to noise and mapping accuracy independent of threshold, quantified using receiver operating characteristic curves. Collectively, our results suggest that modifying the processing of fMRI data to incorporate both task-based and spontaneous activity significantly improves functional localization in pre-operative patients. Because this method requires no additional scan time or modification to conventional pre-operative data acquisition protocols it could have widespread utility. PMID:26408860

  6. Urokinase vs Tissue-Type Plasminogen Activator for Thrombolytic Evacuation of Spontaneous Intracerebral Hemorrhage in Basal Ganglia

    Directory of Open Access Journals (Sweden)

    Yuqian Li

    2017-08-01

    Full Text Available Spontaneous intracerebral hemorrhage (ICH is a devastating form of stroke, which leads to a high rate of mortality and poor neurological outcomes worldwide. Thrombolytic evacuation with urokinase-type plasminogen activator (uPA or tissue-type plasminogen activator (tPA has been showed to be a hopeful treatment for ICH. However, to the best of our knowledge, no clinical trials were reported to compare the efficacy and safety of these two fibrinolytics administrated following minimally invasive stereotactic puncture (MISP in patients with spontaneous basal ganglia ICH. Therefore, the authors intended here to evaluate the differential impact of uPA and tPA in a retrospective study. In the present study, a total of 86 patients with spontaneous ICH in basal ganglia using MISP received either uPA (uPA group, n = 45 or tPA (tPA group, n = 41, respectively. The clinical baseline characteristics prior to the operation were collected. In addition, therapeutic responses were assessed by the short-term outcomes within 30 days postoperation, as well as long-term outcomes at 1 year postoperation. Our findings showed that, in comparison with tPA, uPA was able to better promote hematoma evacuation and ameliorate perihematomal edema, but the differences were not statistically significant. Moreover, the long-term functional outcomes of both groups were similar, with no statistical difference. In conclusion, these results provide evidence supporting that uPA and tPA are similar in the efficacy and safety for thrombolytic evacuation in combination with MISP in patients with spontaneous basal ganglia ICH.

  7. Correlated Production and Analog Transport of Fission Neutrons and Photons using Fission Models FREYA, FIFRELIN and the Monte Carlo Code TRIPOLI-4® .

    Science.gov (United States)

    Verbeke, Jérôme M.; Petit, Odile; Chebboubi, Abdelhazize; Litaize, Olivier

    2018-01-01

    Fission modeling in general-purpose Monte Carlo transport codes often relies on average nuclear data provided by international evaluation libraries. As such, only average fission multiplicities are available and correlations between fission neutrons and photons are missing. Whereas uncorrelated fission physics is usually sufficient for standard reactor core and radiation shielding calculations, correlated fission secondaries are required for specialized nuclear instrumentation and detector modeling. For coincidence counting detector optimization for instance, precise simulation of fission neutrons and photons that remain correlated in time from birth to detection is essential. New developments were recently integrated into the Monte Carlo transport code TRIPOLI-4 to model fission physics more precisely, the purpose being to access event-by-event fission events from two different fission models: FREYA and FIFRELIN. TRIPOLI-4 simulations can now be performed, either by connecting via an API to the LLNL fission library including FREYA, or by reading external fission event data files produced by FIFRELIN beforehand. These new capabilities enable us to easily compare results from Monte Carlo transport calculations using the two fission models in a nuclear instrumentation application. In the first part of this paper, broad underlying principles of the two fission models are recalled. We then present experimental measurements of neutron angular correlations for 252Cf(sf) and 240Pu(sf). The correlations were measured for several neutron kinetic energy thresholds. In the latter part of the paper, simulation results are compared to experimental data. Spontaneous fissions in 252Cf and 240Pu are modeled by FREYA or FIFRELIN. Emitted neutrons and photons are subsequently transported to an array of scintillators by TRIPOLI-4 in analog mode to preserve their correlations. Angular correlations between fission neutrons obtained independently from these TRIPOLI-4 simulations, using

  8. High-Tc superconducting quantum interference device recordings of spontaneous brain activity: Towards high-Tc magnetoencephalography

    Science.gov (United States)

    Öisjöen, F.; Schneiderman, J. F.; Figueras, G. A.; Chukharkin, M. L.; Kalabukhov, A.; Hedström, A.; Elam, M.; Winkler, D.

    2012-03-01

    We have performed single- and two-channel high transition temperature (high-Tc) superconducting quantum interference device (SQUID) magnetoencephalography (MEG) recordings of spontaneous brain activity in two healthy human subjects. We demonstrate modulation of two well-known brain rhythms: the occipital alpha rhythm and the mu rhythm found in the motor cortex. We further show that despite higher noise-levels compared to their low-Tc counterparts, high-Tc SQUIDs can be used to detect and record physiologically relevant brain rhythms with comparable signal-to-noise ratios. These results indicate the utility of high-Tc technology in MEG recordings of a broader range of brain activity.

  9. Langevin model of low-energy fission

    Science.gov (United States)

    Sierk, Arnold J.

    2017-09-01

    Background: Since the earliest days of fission, stochastic models have been used to describe and model the process. For a quarter century, numerical solutions of Langevin equations have been used to model fission of highly excited nuclei, where microscopic potential-energy effects have been neglected. Purpose: In this paper I present a Langevin model for the fission of nuclei with low to medium excitation energies, for which microscopic effects in the potential energy cannot be ignored. Method: I solve Langevin equations in a five-dimensional space of nuclear deformations. The macroscopic-microscopic potential energy from a global nuclear structure model well benchmarked to nuclear masses is tabulated on a mesh of approximately 107 points in this deformation space. The potential is defined continuously inside the mesh boundaries by use of a moving five-dimensional cubic spline approximation. Because of reflection symmetry, the effective mesh is nearly twice this size. For the inertia, I use a (possibly scaled) approximation to the inertia tensor defined by irrotational flow. A phenomenological dissipation tensor related to one-body dissipation is used. A normal-mode analysis of the dynamical system at the saddle point and the assumption of quasiequilibrium provide distributions of initial conditions appropriate to low excitation energies, and are extended to model spontaneous fission. A dynamical model of postscission fragment motion including dynamical deformations and separation allows the calculation of final mass and kinetic-energy distributions, along with other interesting quantities. Results: The model makes quantitative predictions for fragment mass and kinetic-energy yields, some of which are very close to measured ones. Varying the energy of the incident neutron for induced fission allows the prediction of energy dependencies of fragment yields and average kinetic energies. With a simple approximation for spontaneous fission starting conditions

  10. Anti-nerve growth factor therapy increases spontaneous day/night activity in mice with orthopedic surgery-induced pain.

    Science.gov (United States)

    Majuta, Lisa A; Guedon, Jean-Marc G; Mitchell, Stefanie A T; Ossipov, Michael H; Mantyh, Patrick W

    2017-04-01

    Total knee arthroplasty (TKA) and total hip arthroplasty (THA) are 2 of the most common and successful surgical interventions to relieve osteoarthritis pain. Control of postoperative pain is critical for patients to fully participate in the required physical therapy which is the most influential factor in effective postoperative knee rehabilitation. Currently, opiates are a mainstay for managing postoperative orthopedic surgery pain including TKA or THA pain. Recently, issues including efficacy, dependence, overdose, and death from opiates have made clinicians and researchers more critical of use of opioids for treating nonmalignant skeletal pain. In the present report, a nonopiate therapy using a monoclonal antibody raised against nerve growth factor (anti-NGF) was assessed for its ability to increase the spontaneous activity of the operated knee joint in a mouse model of orthopedic surgery pain-induced by drilling and coring the trochlear groove of the mouse femur. Horizontal activity and velocity and vertical rearing were continually assessed over a 20 hours day/night period using automated activity boxes in an effort to reduce observer bias and capture night activity when the mice are most active. At days 1 and 3, after orthopedic surgery, there was a marked reduction in spontaneous activity and vertical rearing; anti-NGF significantly attenuated this decline. The present data suggest that anti-NGF improves limb use in a rodent model of joint/orthopedic surgery and as such anti-NGF may be useful in controlling pain after orthopedic surgeries such as TKA or THA.

  11. Effect of age and severity of cognitive dysfunction on spontaneous activity in pet dogs - part 1: locomotor and exploratory behaviour.

    Science.gov (United States)

    Rosado, B; González-Martínez, A; Pesini, P; García-Belenguer, S; Palacio, J; Villegas, A; Suárez, M-L; Santamarina, G; Sarasa, M

    2012-11-01

    Age-related cognitive dysfunction syndrome (CDS) has been reported in dogs and it is considered a natural model for Alzheimer's disease in humans. Changes in spontaneous activity (including locomotor and exploratory behaviour) and social responsiveness have been related to the age and cognitive status of kennel-reared Beagle dogs. The aim of this study was to assess the influence of age and severity of CDS on locomotor and exploratory behaviour of privately owned dogs. This is the first part of a two-part report on spontaneous activity in pet dogs. An open-field (OF) test and a curiosity test were administered at baseline and 6 months later to young (1-4 years, n=9), middle-aged (5-8 years, n=9), cognitively unimpaired aged (≥ 9 years, n=31), and cognitively impaired aged ( ≥ 9 years, n=36) animals. Classification of cognitive status was carried out using an owner-based observational questionnaire, and in the cognitively impaired group, the dogs were categorised as having either mild or severe cognitive impairment. Dogs were recorded during sessions in the testing room and the video-recordings were subsequently analysed. The severity of CDS (but not age) influenced locomotion and exploratory behaviour so that the more severe the impairment, the higher the locomotor activity and frequency of corner-directed (aimless) behaviours, and the lower the frequency of door-aimed activities. Curiosity directed toward novel stimuli exhibited an age-dependent decline although severely affected animals displayed more sniffing episodes directed towards the objects. OF activity did not change after 6 months. Testing aged pet dogs for spontaneous behaviour might help to better characterise cognitively affected individuals. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Neuronal functional connection graphs among multiple areas of the rat somatosensory system during spontaneous and evoked activities.

    Science.gov (United States)

    Zippo, Antonio G; Storchi, Riccardo; Nencini, Sara; Caramenti, Gian Carlo; Valente, Maurizio; Biella, Gabriele Eliseo M

    2013-01-01

    Small-World Networks (SWNs) represent a fundamental model for the comprehension of many complex man-made and biological networks. In the central nervous system, SWN models have been shown to fit well both anatomical and functional maps at the macroscopic level. However, the functional microscopic level, where the nodes of a network are represented by single neurons, is still poorly understood. At this level, although recent evidences suggest that functional connection graphs exhibit small-world organization, it is not known whether and how these maps, potentially distributed in multiple brain regions, change across different conditions, such as spontaneous and stimulus-evoked activities. We addressed these questions by analyzing the data from simultaneous multi-array extracellular recordings in three brain regions of rats, diversely involved in somatosensory information processing: the ventropostero-lateral thalamic nuclei, the primary somatosensory cortex and the centro-median thalamic nuclei. From both spike and Local Field Potential (LFP) recordings, we estimated the functional connection graphs by using the Normalized Compression Similarity for spikes and the Phase Synchrony for LFPs. Then, by using graph-theoretical statistics, we characterized the functional topology both during spontaneous activity and sensory stimulation. Our main results show that: (i) spikes and LFPs show SWN organization during spontaneous activity; (ii) after stimulation onset, while substantial functional graph reconfigurations occur both in spike and LFPs, small-worldness is nonetheless preserved; (iii) the stimulus triggers a significant increase of inter-area LFP connections without modifying the topology of intra-area functional connections. Finally, investigating computationally the functional substrate that supports the observed phenomena, we found that (iv) the fundamental concept of cell assemblies, transient groups of activating neurons, can be described by small

  13. Sources of variation and genetic profile of spontaneous, out-of-season ovulatory activity in the Chios sheep

    Directory of Open Access Journals (Sweden)

    Kouttos Athanasios

    2003-01-01

    Full Text Available Abstract Organising the breeding plan of a seasonally breeding species, such as sheep, presents a challenge to farmers and the industry as a whole, since both economical and biological considerations need to be carefully balanced. Understanding the breeding activity of individual animals becomes a prerequisite for a successful breeding program. This study set out to investigate the sources of variation and the genetic profile of the spontaneous, out-of-season ovulatory activity of ewes of the Chios dairy sheep breed in Greece. The definition of the trait was based on blood progesterone levels, measured before exposing the ewes to rams, which marks the onset of the usual breeding season. Data were 707 records, taken over two consecutive years, of 435 ewes kept at the Agricultural Research Station of Chalkidiki in northern Greece. When all available pedigree was included, the total number of animals involved was 1068. On average, 29% of all ewes exhibited spontaneous, out-of-season ovulatory activity, with no substantial variation between the years. Significant sources of systematic variation were the ewe age and live weight, and the month of previous lambing. Older, heavier ewes, that had lambed early the previous autumn, exhibited more frequent activity. Heritability estimates were 0.216 (± 0.084 with a linear and 0.291 with a threshold model. The latter better accounts for the categorical nature of the trait. The linear model repeatability was 0.230 (± 0.095. The results obtained in this study support the notion that spontaneous out-of-season ovulatory activity can be considered in the development of a breeding plan for the Chios sheep breed.

  14. Fission cross section measurements at intermediate energies

    International Nuclear Information System (INIS)

    Laptev, Alexander

    2005-01-01

    The activity in intermediate energy particle induced fission cross-section measurements of Pu, U isotopes, minor actinides and sub-actinides in PNPI of Russia is reviewed. The neutron-induced fission cross-section measurements are under way in the wide energy range of incident neutrons from 0.5 MeV to 200 MeV at the GNEIS facility. In number of experiments at the GNEIS facility, the neutron-induced fission cross sections were obtained for many nuclei. In another group of experiments the proton-induced fission cross-section have been measured for proton energies ranging from 200 to 1000 MeV at 100 MeV intervals using the proton beam of PNPI synchrocyclotron. (author)

  15. VESPA. Behaviour of long-lived fission and activation products in the nearfield of a nuclear waste repository and the possibilities of their retention

    Energy Technology Data Exchange (ETDEWEB)

    Bischofer, Barbara; Hagemann, Sven [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) gGmbH, Koeln (Germany); Altmaier, Marcus [Karlsruher Institut fuer Technologie (KIT) (Germany); and others

    2016-06-15

    The present document is the final report of the Joint Research Project VESPA (Behaviour of Long-lived Fission and Activation Products in the Near Field of a Nuclear Waste Repository and the Possibilities of Their Retention), started in July 2010 with a duration of four years. The following four institutions were collaborative Partners in VESPA: - Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) gGmbH - Institut fuer Energie- und Klimaforschung, IEK-6: Nukleare Entsorgung und Reaktorsicherheit, Forschungszentrum Juelich (FZJ) - Institut fuer Ressourcenoekologie (IRE), Helmholtz-Zentrum Dresden-Rossendorf (HZDR) - Institut fuer Nukleare Entsorgung (INE), Karlsruher Institut fuer Technologie (KIT) VESPA was funded by the German Federal Ministry of Economics and Energy (BMWi) under the contract numbers 02 E 10770 (GRS), 02 E 10780 (FZJ-IEF-6), 02 E 10790 (HZDR-IRE), 02 E 10800 (KIT-INE).

  16. Prompt γ rays and neutrons from fission

    Science.gov (United States)

    Kwan, E.; Wu, C. Y.; Chyzh, A.; Gostic, J.; Henderson, R.; Haight, R. C.; Lee, H. Y.; O'Donnell, J. M.; Perdue, B. A.; Taddeucci, T. N.

    2011-10-01

    Nuclear data are needed to test the accuracy of calculations from nuclear reaction codes. Information on the prompt γ-ray distributions from fission is sparse and only a handful of published experiments data that measured the prompt γ-ray distribution above incident neutron energies of 1 MeV can be found. In addition, improvement on the accuracy and shape of neutron spectrum from the fission of actinides been requested by the nuclear data community. An investigation on the shapes of the neutron and γ-ray distributions from the spontaneous fission of 252Cf and the neutron-induced fission of 235U was undertaken using the Chi-Nu detector array at the Weapons Neutron Research Facility of the Los Alamos Neutron Science Center. Preliminary results will be presented. This work is performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and the Los Alamos National Laboratory under Contract DE-AC52-06NA25396.

  17. Fission properties and production mechanisms for the heaviest known elements

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, D.C.

    1981-01-01

    Mass yields of the spontaneous fission of Fm isotopes, Cf isotopes, and /sup 259/Md are discussed. Actinide yields were measured for bombardments of /sup 248/Cm with /sup 16/O, /sup 18/O, /sup 20/Ne, and /sup 22/Ne. A superheavy product might be produced by bombarding /sup 248/Cm with /sup 48/Ca ions. 12 figures. (DLC)

  18. Spontaneous food allergy in Was-/-mice occurs independent of FcεRI-mediated mast cell activation.

    Science.gov (United States)

    Lexmond, W S; Goettel, J A; Sallis, B F; McCann, K; Rings, E H H M; Jensen-Jarolim, E; Nurko, S; Snapper, S B; Fiebiger, E

    2017-12-01

    Food allergies are a growing health problem, and the development of therapies that prevent disease onset is limited by the lack of adjuvant-free experimental animal models. We compared allergic sensitization in patients with food allergy or Wiskott-Aldrich syndrome (WAS) and defined whether spontaneous disease in Was -/- mice recapitulates the pathology of a conventional disease model and/or human food allergy. Comparative ImmunoCAP ISAC microarray was performed in patients with food allergy or WAS. Spontaneous food allergy in Was -/- mice was compared to an adjuvant-based model in wild-type mice (WT-OVA/alum). Intestinal and systemic anaphylaxis was assessed, and the role of the high-affinity IgE Fc receptor (FcεRI) in allergic sensitization was evaluated using Was -/- Fcer1a -/- mice. Polysensitization to food was detected in both WAS and food-allergic patients which was recapitulated in the Was -/- model. Oral administration of ovalbumin (OVA) in Was -/- mice induced low titers of OVA-specific IgE compared to the WT-OVA/alum model. Irrespectively, 79% of Was -/- mice developed allergic diarrhea following oral OVA challenge. Systemic anaphylaxis occurred in Was -/- mice (95%) with a mortality rate >50%. Spontaneous sensitization and intestinal allergy occurred independent of FcεRI expression on mast cells (MCs) and basophils. Was -/- mice provide a model of food allergy with the advantage of mimicking polysensitization and low food-antigen IgE titers as observed in humans with clinical food allergy. This model will facilitate studies on aberrant immune responses during spontaneous disease development. Our results imply that therapeutic targeting of the IgE/FcεRI activation cascade will not affect sensitization to food. © 2017 EAACI and John Wiley and Sons A/S. Published by John Wiley and Sons Ltd.

  19. Fission products determination in high activity waste solution by wavelength dispersive X-ray fluorescence spectral interference correction by intensity ratio

    International Nuclear Information System (INIS)

    Sato, I.M.

    1988-01-01

    Fission products Se, Rb, Y, Zr, Mo, Ru, Rh, Pd, Te, Cd, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu and Gd were determined in simulated high activity radioactive waste solution by wavelength dispersive X-ray fluorescence spectrometry without chemical separation. Thin layer technique was employed for the sample preparation. For the L spectral lines, the absorption effect was verified by Rasberry-Heinrich, Lucas Tooth-Pyne and Lachance-Trail relations. This effect was quantified and corrected accordingly. The spectral interferences of Kα and/or Lα lines of Y, Zr, Mo, La, Ce, Pr, Nd, Sm, Eu and Gd elements were eliminated by the intensity ratio method. The overlapping of up to three analytical lines was corrected by applying this method. The concentration influence of the interfering element on the intensity ratio values as well the efficiency of the correction method were investigated in order to assure that no systematic or residual error, resulting from the correction, affect the actual fluorescent intensity determination. The results is compared with the data obtained from measurements of free lines of spectral interference and also with those obtained by the linear equation system. Fission products determination presented a precision in the range of 0.1 to 5.0% and an accuracy of up to ± 7.0% the results are compared with those obtained by neutron activation analysis and inductively coupled plasma - atomic emission spectrometry. Leaching data, when radioactive waste is incorporated in cement matrix, were attempted by X-ray fluorescence technique. For two years leaching period, leaching rate and diffusion coefficient data of cesium were determined. The results obtained agree with those obtained by γ-spectromety. (author) [pt

  20. Spontaneous Brain Activity Did Not Show the Effect of Violent Video Games on Aggression: A Resting-State fMRI Study

    OpenAIRE

    Wei Pan; Wei Pan; Wei Pan; Xuemei Gao; Shuo Shi; Fuqu Liu; Chao Li

    2018-01-01

    A great many of empirical researches have proved that longtime exposure to violent video game can lead to a series of negative effects. Although research has focused on the neural basis of the correlation between violent video game and aggression, little is known whether the spontaneous brain activity is associated with violent video game exposure. To address this question, we measured the spontaneous brain activity using resting-state functional magnetic resonance imaging (fMRI). We used the...

  1. A high-fat diet rich in corn oil reduces spontaneous locomotor activity and induces insulin resistance in mice.

    Science.gov (United States)

    Wong, Chi Kin; Botta, Amy; Pither, Jason; Dai, Chuanbin; Gibson, William T; Ghosh, Sanjoy

    2015-04-01

    Over the last few decades, polyunsaturated fatty acid (PUFA), especially n-6 PUFA, and monounsaturated fatty acid content in 'Western diets' has increased manyfold. Such a dietary shift also parallels rising sedentary behavior and diabetes in the Western world. We queried if a shift in dietary fats could be linked to physical inactivity and insulin insensitivity in mice. Eight-week old female C57/Bl6 mice were fed either high-fat (HF) diets [40% energy corn oil (CO) or isocaloric olive oil (OO) diets] or chow (n=10/group) for 6 weeks, followed by estimation of spontaneous locomotor activity, body composition and in vivo metabolic outcomes. Although lean mass and resting energy expenditure stayed similar in both OO- and CO-fed mice, only CO-fed mice demonstrated reduced spontaneous locomotor activity. Such depressed activity in CO-fed mice was accompanied by a lower respiratory ratio, hyperinsulinemia and impaired glucose disposal following intraperitoneal glucose tolerance and insulin tolerance tests compared to OO-fed mice. Unlike the liver, where both HF diets increased expression of fat oxidation genes like PPARs, the skeletal muscle of CO-fed mice failed to up-regulate such genes, thereby supporting the metabolic insufficiencies observed in these mice. In summary, this study demonstrates a specific contribution of n-6 PUFA-rich oils like CO to the loss of spontaneous physical activity and insulin sensitivity in mice. If these data hold true for humans, this study could provide a novel link between recent increases in dietary n-6 PUFA to sedentary behavior and the development of insulin resistance in the Western world. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Fission in a Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Younes, W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-10-26

    A three-year theory project was undertaken to study the fission process in extreme astrophysical environments, such as the crust of neutron stars. In the first part of the project, the effect of electron screening on the fission process was explored using a microscopic approach. For the first time, these calculations were carried out to the breaking point of the nucleus. In the second part of the project, the population of the fissioning nucleus was calculated within the same microscopic framework. These types of calculations are extremely computer-intensive and have seldom been applied to heavy deformed nuclei, such as fissioning actinides. The results, tools and methodologies produced in this work will be of interest to both the basic-science and nuclear-data communities.

  3. Attachment behavior of fission products to solution aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Takamiya, Koichi; Tanaka, Toru; Nitta, Shinnosuke; Itosu, Satoshi; Sekimoto, Shun; Oki, Yuichi; Ohtsuki, Tsutomu [Research Reactor Institute, Kyoto University, Osaka (Japan)

    2016-12-15

    Various characteristics such as size distribution, chemical component and radioactivity have been analyzed for radioactive aerosols released from Fukushima Daiichi Nuclear Power Plant. Measured results for radioactive aerosols suggest that the potential transport medium for radioactive cesium was non-sea-salt sulfate. This result indicates that cesium isotopes would preferentially attach with sulfate compounds. In the present work the attachment behavior of fission products to aqueous solution aerosols of sodium salts has been studied using a generation system of solution aerosols and spontaneous fission source of {sup 248}Cm. Attachment ratios of fission products to the solution aerosols were compared among the aerosols generated by different solutions of sodium salt. A significant difference according as a solute of solution aerosols was found in the attachment behavior. The present results suggest the existence of chemical effects in the attachment behavior of fission products to solution aerosols.

  4. Determination of the fission products yields, lanthanide and yttrium, in the fission of 238U with neutrons of fission spectra

    International Nuclear Information System (INIS)

    Nicoli, I.G.

    1981-06-01

    A radiochemical investigation is performed to measure the cumulative fission product yields of several lantanides and yttrium nuclides in the 238 U by fission neutron spectra. Natural and depleted uranium are irradiated under the same experimental conditions in order to find a way to subtract the contribution of the 235 U fission. 235 U percentage in the natural uranium was 3.5 times higher than in the depleted uranium. Uranium oxides samples are irradiated inside the core of the Argonaut Reactor, at the Instituto de Engenharia Nuclear, and the lantanides and yttrium are chemically separated. The fission products gamma activities were detected, counted and analysed in a system constituted by a high resolution Ge(Li) detector, 4096 multichannel analyser and a PDP-11 computer. Cumulative yields for fission products with half-lives between 1 to 33 hours are measured: 93 Y, 141 La, 142 La, 143 Ce and 149 Nd. The chain total yields are calculated. The cumulative fission yields measured for 93 Y, 141 La, 142 La, 143 Ce and 149 Nd are 4,49%, 4,54%, 4,95%, 4,16% and 1,37% respectively and they are in good agreement with the values found in the literature. (Author) [pt

  5. Comparative Analysis of Human and Rodent Brain Primary Neuronal Culture Spontaneous Activity Using Micro-Electrode Array Technology.

    Science.gov (United States)

    Napoli, Alessandro; Obeid, Iyad

    2016-03-01

    Electrical activity in embryonic brain tissue has typically been studied using Micro Electrode Array (MEA) technology to make dozens of simultaneous recordings from dissociated neuronal cultures, brain stem cell progenitors, or brain slices from fetal rodents. Although these rodent neuronal primary culture electrical properties are mostly investigated, it has not been yet established to what extent the electrical characteristics of rodent brain neuronal cultures can be generalized to those of humans. A direct comparison of spontaneous spiking activity between rodent and human primary neurons grown under the same in vitro conditions using MEA technology has never been carried out before and will be described in the present study. Human and rodent dissociated fetal brain neuronal cultures were established in-vitro by culturing on a glass grid of 60 planar microelectrodes neurons under identical conditions. Three different cultures of human neurons were produced from tissue sourced from a single aborted fetus (at 16-18 gestational weeks) and these were compared with seven different cultures of embryonic rat neurons (at 18 gestational days) originally isolated from a single rat. The results show that the human and rodent cultures behaved significantly differently. Whereas the rodent cultures demonstrated robust spontaneous activation and network activity after only 10 days, the human cultures required nearly 40 days to achieve a substantially weaker level of electrical function. These results suggest that rat neuron preparations may yield inferences that do not necessarily transfer to humans. © 2015 Wiley Periodicals, Inc.

  6. Anisotropic Neutron Evaporation from Spinning Fission Fragments

    Science.gov (United States)

    Stuttgé, L.; Dorvaux, O.; Gönnenwein, F.; Mutterer, M.; Kopatch, Yu.; Chernysheva, E.; Hanappe, F.; Hambsch, F.-J.

    2011-10-01

    Neutron evaporation anisotropy in the centre of mass of the rotating fission fragments in the spontaneous fission of 252Cf has been investigated within the CORA experiments. If it is well accepted that the bulk of emitted neutrons originate from an isotropic evaporation in the centre of mass of the moving fragments, discrepancies in experimental as well as in theoretical energy and angular distributions appear throughout many attempts performed by various authors. Scission neutrons most probably contribute but don't allow to explain totally the observed anisotropy. Due to its weak contribution to the total anisotropy, the centre of mass anisotropy is very difficult to be highlighted. A novel experimental approach has been developed to extract this effect and will be presented as well as some first results.

  7. Nuclear fission: What have we learned in 50 years?

    International Nuclear Information System (INIS)

    Vandenbosch, R.

    1989-01-01

    Nuclear fission has captured the imagination of chemists and physicists for half a century now. There are several reasons for this. One of course is that it represents the most drastic rearrangement of nuclear matter known, challenged only recently by collisions induced by very heavy ions. Another is that both statistical and dynamical features come into play. Perhaps one of the most compelling reasons is its never-ending capacity to surprise us: asymmetric mass distributions, the sawtooth dependence of neutron yields in fragment mass, spontaneously fissioning isomers and intermediate structure resonances. Finally, and perhaps most importantly, fission is a rich laboratory within which one can explore the delicate interplay between the macroscopic aspects of bulk nuclear matter and the quantal effects of a finite number of Fermions. It will of course be impossible for me to cover all aspects of fission. I have chosen a limited number of topics to cover, with particular topics being chosen either because the have been associated with persistent puzzles in fission or because they have, or hopefully will, tell us something special about how nuclei behave. After a brief historical note, I organize these topics sequentially according to the various stages of the fission process, starting first with the probability for fission to occur and ending with scission phenomena. 56 refs., 11 figs

  8. Relaxant effect of a novel calcium-activated potassium channel modulator on human myometrial spontaneous contractility in vitro

    DEFF Research Database (Denmark)

    Rosenbaum, S.T.; Larsen, T.; Joergensen, J.C.

    2012-01-01

    Aim: To investigate the effect of 4,5-dichloro-1,3-diethyl-1,3-dihydro-benzoimidazol-2-one (NS4591), a novel SK/IK channels positive modulator, on human myometrial activity. Methods: Organ bath studies were performed on myometrial preparations obtained from women undergoing elective caesarean....... Simultaneous vehicle controls were performed for all experiments. The effects of drugs were studied on spontaneous contractions. Results: NS4591 exerted an inhibitory effect on myometrial contractions in muscle strips from non-pregnant and pregnant women. The contractility in non-pregnant and pregnant...

  9. Normal patterns of spontaneous activity are required for correct motor axon guidance and the expression of specific guidance molecules.

    Science.gov (United States)

    Hanson, M Gartz; Landmesser, Lynn T

    2004-09-02

    Rhythmic spontaneous electrical activity occurs in many parts of the developing nervous system, where it plays essential roles in the refinement of neural connections. By blocking or slowing this bursting activity, via in ovo drug applications at precise developmental periods, we show that such activity is also required at much earlier stages for spinal motoneurons to accurately execute their first major dorsal-ventral pathfinding decision. Blockade or slowing of rhythmic bursting activity also prevents the normal expression patterns of EphA4 and polysialic acid on NCAM, which may contribute to the pathfinding errors observed. More prolonged (E2-5) blockade resulted in a downregulation of LIM homeodomain transcription factors, but since this occurred only after the pathfinding errors and alterations in guidance molecules, it cannot have contributed to them.

  10. Spontaneous pneumothorax

    Directory of Open Access Journals (Sweden)

    Davari R

    1996-07-01

    Full Text Available A case with bilateral spontaneous pneumothorax was presented. Etiology, mechanism, and treatment were discussed on the review of literature. Spontaneous Pneumothorax is a clinical entity resulting from a sudden non traumatic rupture of the lung. Biach reported in 1880 that 78% of 916 patients with spontaneous pneumothorax had tuberculosis. Kjergaard emphasized 1932 the primary importance of subpleural bleb disease. Currently the clinical spectrum of spontaneous pneumothorax seems to have entered a third era with the recognition of the interstitial lung disease and AIDS as a significant etiology. Standard treatment is including: observation, thoracocentesis, tube thoracostomy. Chemical pleurodesis, bullectomy or wedge resection of lung with pleural abrasion and occasionally pleurectomy. Little information has been reported regarding the efficacy of such treatment in spontaneous pneumothorax secondary to non bleb disease

  11. A fission-fragment-sensitive target for X-ray spectroscopy in neutron-induced fission

    CERN Document Server

    Ethvignot, T; Giot, L; Casoli, P; Nelson, R O

    2002-01-01

    A fission-fragment-sensitive detector built for low-energy photon spectroscopy applications at the WNR 'white' neutron source at Los Alamos is described. The detector consists of eight layers of thin photovoltaic cells, onto which 1 mg/cm sup 2 of pure sup 2 sup 3 sup 8 U is deposited. The detector serves as an active target to select fission events from background and other reaction channels. The fairly small thickness of the detector with respect to transmission of 20-50 keV photons permits the measurement of prompt fission-fragment X-rays. Results with the GEANIE photon spectrometer are presented.

  12. Self-monitoring of spontaneous physical activity and sedentary behavior to prevent weight regain in older adults

    Science.gov (United States)

    Nicklas, Barbara J.; Gaukstern, Jill E.; Beavers, Kristen M.; Newman, Jill C.; Leng, Xiaoyan; Rejeski, W. Jack

    2014-01-01

    Objective This study determined whether adding a self-regulatory intervention (SRI) focused on self-monitoring of spontaneous physical activity and sedentary behavior to a standard weight loss intervention improved maintenance of lost weight. Design and Methods Older (65–79 yrs), obese (BMI=30–40 kg/m2) adults (n=48) were randomized to a five-month weight loss intervention involving a hypocaloric diet (DIET) and aerobic exercise (EX) with or without the SRI to promote spontaneous physical activity and decrease sedentary behavior (SRI+DIET+EX compared to DIET+EX). Following the weight loss phase, both groups transitioned to self-selected diet and exercise behavior during a 5-month follow-up. Throughout the 10-months, the SRI+DIET+EX group utilized real-time accelerometer feedback for self-monitoring. Results There was an overall group by time effect of the SRI (P physical activity and decrease sedentary behavior, to a standard weight loss intervention enhances successful maintenance of lost weight. PMID:24585701

  13. Combining task-evoked and spontaneous activity to improve pre-operative brain mapping with fMRI.

    Science.gov (United States)

    Fox, Michael D; Qian, Tianyi; Madsen, Joseph R; Wang, Danhong; Li, Meiling; Ge, Manling; Zuo, Huan-Cong; Groppe, David M; Mehta, Ashesh D; Hong, Bo; Liu, Hesheng

    2016-01-01

    Noninvasive localization of brain function is used to understand and treat neurological disease, exemplified by pre-operative fMRI mapping prior to neurosurgical intervention. The principal approach for generating these maps relies on brain responses evoked by a task and, despite known limitations, has dominated clinical practice for over 20years. Recently, pre-operative fMRI mapping based on correlations in spontaneous brain activity has been demonstrated, however this approach has its own limitations and has not seen widespread clinical use. Here we show that spontaneous and task-based mapping can be performed together using the same pre-operative fMRI data, provide complimentary information relevant for functional localization, and can be combined to improve identification of eloquent motor cortex. Accuracy, sensitivity, and specificity of our approach are quantified through comparison with electrical cortical stimulation mapping in eight patients with intractable epilepsy. Broad applicability and reproducibility of our approach are demonstrated through prospective replication in an independent dataset of six patients from a different center. In both cohorts and every individual patient, we see a significant improvement in signal to noise and mapping accuracy independent of threshold, quantified using receiver operating characteristic curves. Collectively, our results suggest that modifying the processing of fMRI data to incorporate both task-based and spontaneous activity significantly improves functional localization in pre-operative patients. Because this method requires no additional scan time or modification to conventional pre-operative data acquisition protocols it could have widespread utility. Copyright © 2015. Published by Elsevier Inc.

  14. The dynamics of cortical neuronal activity in the first minutes after spontaneous awakening in rats and mice.

    Science.gov (United States)

    Vyazovskiy, Vladyslav V; Cui, Nanyi; Rodriguez, Alexander V; Funk, Chadd; Cirelli, Chiara; Tononi, Giulio

    2014-08-01

    Upon awakening from sleep, a fully awake brain state is not reestablished immediately, but the origin and physiological properties of the distinct brain state during the first min after awakening are unclear. To investigate whether neuronal firing immediately upon arousal is different from the remaining part of the waking episode, we recorded and analyzed the dynamics of cortical neuronal activity in the first 15 min after spontaneous awakenings in freely moving rats and mice. Intracortical recordings of the local field potential and neuronal activity in freely-moving mice and rats. Basic sleep research laboratory. WKY adult male rats, C57BL/6 adult male mice. N/A. In both species the average population spiking activity upon arousal was initially low, though substantial variability in the dynamics of firing activity was apparent between individual neurons. A distinct population of neurons was found that was virtually silent in the first min upon awakening. The overall lower population spiking initially after awakening was associated with the occurrence of brief periods of generalized neuronal silence (OFF periods), whose frequency peaked immediately after awakening and then progressively declined. OFF periods incidence upon awakening was independent of ongoing locomotor activity but was sensitive to immediate preceding sleep/wake history. Notably, in both rats and mice if sleep before a waking episode was enriched in rapid eye movement sleep, the incidence of OFF periods was initially higher as compared to those waking episodes preceded mainly by nonrapid eye movement sleep. We speculate that an intrusion of sleep-like patterns of cortical neuronal activity into the wake state immediately after awakening may account for some of the changes in the behavior and cognitive function typical of what is referred to as sleep inertia. Vyazovskiy VV, Cui N, Rodriguez AV, Funk C, Cirelli C, Tononi G. The dynamics of cortical neuronal activity in the first minutes after

  15. Translational Science: How experimental research has contributed to the understanding of spontaneous Physical Activity and Energy Homeostasis

    Directory of Open Access Journals (Sweden)

    Izabelle D Benfato

    2017-05-01

    Full Text Available Abstract Spontaneous physical activity (SPA consists of all daily living activities other than volitional exercise (e.g. sports and fitness-related activities. SPA is an important component of energy expenditure and may protect from overweight and obesity. Little is known about the biological regulation of SPA, but animal researchhas contributedsignificantly to expand our knowledge in this field. Studies in rodents have shown that SPA is influenced by nutrients and volitional exercise. High-fat diet seems to decrease SPA, which contributes to weigh gain. Volitional exercisemayalso reduce SPA, helping to explain the commonly reported low efficiency of exercise to cause weight loss, and highlighting the need to finda volume/intensity of exercise to maximize total daily energy expenditure. Animal studieshave also allowed for the identification of some brain areas and chemical mediatorsinvolved in SPA regulation. These discoveries could enable the development of new therapeutics aiming to enhance SPA.

  16. Spontaneous activity in electromyography may differentiate certain benign lower motor neuron disease forms from amyotrophic lateral sclerosis.

    Science.gov (United States)

    Jokela, Manu E; Jääskeläinen, Satu K; Sandell, Satu; Palmio, Johanna; Penttilä, Sini; Saukkonen, Annamaija; Soikkeli, Raija; Udd, Bjarne

    2015-08-15

    There is limited data on electromyography (EMG) findings in other motor neuron disorders than amyotrophic lateral sclerosis (ALS). We assessed whether the distribution of active denervation detected by EMG, i.e. fibrillations and fasciculations, differs between ALS and slowly progressive motor neuron disorders. We compared the initial EMG findings of 43 clinically confirmed, consecutive ALS patients with those of 41 genetically confirmed Late-onset Spinal Motor Neuronopathy and 14 Spinal and Bulbar Muscular Atrophy patients. Spontaneous activity was more frequently detected in the first dorsal interosseus and deltoid muscles of ALS patients than in patients with the slowly progressive motor neuron diseases. The most important observation was that absent fibrillations in the first dorsal interosseus muscle identified the benign forms with sensitivities of 66%-77% and a specificity of 93%. The distribution of active denervation may help to separate ALS from mimicking disorders at an early stage. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Spontaneous Cdc42 polarization independent of GDI-mediated extraction and actin-based trafficking.

    Directory of Open Access Journals (Sweden)

    Felipe O Bendezú

    2015-04-01

    Full Text Available The small Rho-family GTPase Cdc42 is critical for cell polarization and polarizes spontaneously in absence of upstream spatial cues. Spontaneous polarization is thought to require dynamic Cdc42 recycling through Guanine nucleotide Dissociation Inhibitor (GDI-mediated membrane extraction and vesicle trafficking. Here, we describe a functional fluorescent Cdc42 allele in fission yeast, which demonstrates Cdc42 dynamics and polarization independent of these pathways. Furthermore, an engineered Cdc42 allele targeted to the membrane independently of these recycling pathways by an amphipathic helix is viable and polarizes spontaneously to multiple sites in fission and budding yeasts. We show that Cdc42 is highly mobile at the membrane and accumulates at sites of activity, where it displays slower mobility. By contrast, a near-immobile transmembrane domain-containing Cdc42 allele supports viability and polarized activity, but does not accumulate at sites of activity. We propose that Cdc42 activation, enhanced by positive feedback, leads to its local accumulation by capture of fast-diffusing inactive molecules.

  18. General Description of Fission Observables: GEF Model Code

    Science.gov (United States)

    Schmidt, K.-H.; Jurado, B.; Amouroux, C.; Schmitt, C.

    2016-01-01

    The GEF ("GEneral description of Fission observables") model code is documented. It describes the observables for spontaneous fission, neutron-induced fission and, more generally, for fission of a compound nucleus from any other entrance channel, with given excitation energy and angular momentum. The GEF model is applicable for a wide range of isotopes from Z = 80 to Z = 112 and beyond, up to excitation energies of about 100 MeV. The results of the GEF model are compared with fission barriers, fission probabilities, fission-fragment mass- and nuclide distributions, isomeric ratios, total kinetic energies, and prompt-neutron and prompt-gamma yields and energy spectra from neutron-induced and spontaneous fission. Derived properties of delayed neutrons and decay heat are also considered. The GEF model is based on a general approach to nuclear fission that explains a great part of the complex appearance of fission observables on the basis of fundamental laws of physics and general properties of microscopic systems and mathematical objects. The topographic theorem is used to estimate the fission-barrier heights from theoretical macroscopic saddle-point and ground-state masses and experimental ground-state masses. Motivated by the theoretically predicted early localisation of nucleonic wave functions in a necked-in shape, the properties of the relevant fragment shells are extracted. These are used to determine the depths and the widths of the fission valleys corresponding to the different fission channels and to describe the fission-fragment distributions and deformations at scission by a statistical approach. A modified composite nuclear-level-density formula is proposed. It respects some features in the superfluid regime that are in accordance with new experimental findings and with theoretical expectations. These are a constant-temperature behaviour that is consistent with a considerably increased heat capacity and an increased pairing condensation energy that is

  19. Modulation by endothelin-1 of spontaneous activity and membrane currents of atrioventricular node myocytes from the rabbit heart.

    Directory of Open Access Journals (Sweden)

    Stéphanie C Choisy

    Full Text Available The atrioventricular node (AVN is a key component of the cardiac pacemaker-conduction system. Although it is known that receptors for the peptide hormone endothelin-1 (ET-1 are expressed in the AVN, there is very little information available on the modulatory effects of ET-1 on AVN electrophysiology. This study characterises for the first time acute modulatory effects of ET-1 on AVN cellular electrophysiology.Electrophysiological experiments were conducted in which recordings were made from rabbit isolated AVN cells at 35-37°C using the whole-cell patch clamp recording technique.Application of ET-1 (10 nM to spontaneously active AVN cells led rapidly (within ~13 s to membrane potential hyperpolarisation and cessation of spontaneous action potentials (APs. This effect was prevented by pre-application of the ET(A receptor inhibitor BQ-123 (1 µM and was not mimicked by the ET(B receptor agonist IRL-1620 (300 nM. In whole-cell voltage-clamp experiments, ET-1 partially inhibited L-type calcium current (I(Ca,L and rapid delayed rectifier K(+ current (I(Kr, whilst it transiently activated the hyperpolarisation-activated current (I(f at voltages negative to the pacemaking range, and activated an inwardly rectifying current that was inhibited by both tertiapin-Q (300 nM and Ba(2+ ions (2 mM; each of these effects was sensitive to ET(A receptor inhibition. In cells exposed to tertiapin-Q, ET-1 application did not produce membrane potential hyperpolarisation or immediate cessation of spontaneous activity; instead, there was a progressive decline in AP amplitude and depolarisation of maximum diastolic potential.Acutely applied ET-1 exerts a direct modulatory effect on AVN cell electrophysiology. The dominant effect of ET-1 in this study was activation of a tertiapin-Q sensitive inwardly rectifying K(+ current via ET(A receptors, which led rapidly to cell quiescence.

  20. Monte-Carlo Generation of Time Evolving Fission Chains

    Energy Technology Data Exchange (ETDEWEB)

    Verbeke, Jerome M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kim, Kenneth S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Prasad, Manoj K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Snyderman, Neal J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2013-08-01

    About a decade ago, a computer code was written to model neutrons from their “birth” to their final “death” in thermal neutron detectors (3He tubes): SrcSim had enough physics to track the neutrons in multiplying systems, appropriately increasing and decreasing the neutron population as they interacted by absorption, fission and leakage. The theory behind the algorithms assumed that all neutrons produced in a fission chain were all produced simultaneously, and then diffused to the neutron detectors. For cases where the diffusion times are long compared to the fission chains, SrcSim is very successful. Indeed, it works extraordinarily well for thermal neutron detectors and bare objects, because it takes tens of microseconds for fission neutrons to slow down to thermal energies, where they can be detected. Microseconds are a very long time compared to the lengths of the fission chains. However, this inherent assumption in the theory prevents its use to cases where either the fission chains are long compared to the neutron diffusion times (water-cooled nuclear reactors, or heavily moderated object, where the theory starts failing), or the fission neutrons can be detected shortly after they were produced (fast neutron detectors). For these cases, a new code needs to be written, where the underlying assumption is not made. The purpose of this report is to develop an algorithm to generate the arrival times of neutrons in fast neutron detectors, starting from a neutron source such as a spontaneous fission source (252Cf) or a multiplying source (Pu). This code will be an extension of SrcSim to cases where correlations between neutrons in the detectors are on the same or shorter time scales as the fission chains themselves.

  1. Recent improvements in the calculation of prompt fission neutron spectra: Preliminary results

    International Nuclear Information System (INIS)

    Madland, D.G.; LaBauve, R.J.; Nix, J.R.

    1989-01-01

    We consider three topics in the refinement and improvement of our original calculations of prompt fission neutron spectra. These are an improved calculation of the prompt fission neutron spectrum N(E) from the spontaneous fission of 252 Cf, a complete calculation of the prompt fission neutron spectrum matrix N(E,E n ) from the neutron-induced fission of 235 U, at incident neutron energies ranging from 0 to 15 MeV, and an assessment of the scission neutron component of the prompt fission neutron spectrum. Preliminary results will be presented and compared with experimental measurements and an evaluation. A suggestion is made for new integral cross section measurements. (author). 45 refs, 12 figs, 1 tab

  2. Fission fragment angular momentum

    International Nuclear Information System (INIS)

    Frenne, D. De

    1991-01-01

    Most of the energy released in fission is converted into translational kinetic energy of the fragments. The remaining excitation energy will be distributed among neutrons and gammas. An important parameter characterizing the scission configuration is the primary angular momentum of the nascent fragments. Neutron emission is not expected to decrease the spin of the fragments by more than one unit of angular momentum and is as such of less importance in the determination of the initial fragment spins. Gamma emission is a suitable tool in studying initial fragment spins because the emission time, number, energy, and multipolarity of the gammas strongly depend on the value of the primary angular momentum. The main conclusions of experiments on gamma emission were that the initial angular momentum of the fragments is large compared to the ground state spin and oriented perpendicular to the fission axis. Most of the recent information concerning initial fragment spin distributions comes from the measurement of isomeric ratios for isomeric pairs produced in fission. Although in nearly every mass chain isomers are known, only a small number are suitable for initial fission fragment spin studies. Yield and half-life considerations strongly limit the number of candidates. This has the advantage that the behavior of a specific isomeric pair can be investigated for a number of fissioning systems at different excitation energies of the fragments and fissioning nuclei. Because most of the recent information on primary angular momenta comes from measurements of isomeric ratios, the global deexcitation process of the fragments and the calculation of the initial fragment spin distribution from measured isomeric ratios are discussed here. The most important results on primary angular momentum determinations are reviewed and some theoretical approaches are given. 45 refs., 7 figs., 2 tabs

  3. Fission gas measuring technology

    International Nuclear Information System (INIS)

    Lee, Hyung Kwon; Kim, Eun Ka; Hwang, Yong Hwa; Lee, Eun Pyo; Chun, Yong Bum; Seo, Ki Seog; Park, Dea Gyu; Chu, Yong Sun; Ahn, Sang Bok.

    1998-02-01

    Safety and economy of nuclear plant are greatly affected by the integrity of nuclear fuels during irradiation reactor core. A series of post-irradiation examination (PIE) including non-destructive and destructive test is to be conducted to evaluate and characterize the nuclear performance. In this report, a principle of the examination equipment to measure and analyse fission gases existing nuclear fuels were described and features of the component and device consisting the fission gas measuring equipment are investigated. (author). 4 refs., 2 tabs., 6 figs

  4. Fission gas measuring technology

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyung Kwon; Kim, Eun Ka; Hwang, Yong Hwa; Lee, Eun Pyo; Chun, Yong Bum; Seo, Ki Seog; Park, Dea Gyu; Chu, Yong Sun; Ahn, Sang Bok

    1998-02-01

    Safety and economy of nuclear plant are greatly affected by the integrity of nuclear fuels during irradiation reactor core. A series of post-irradiation examination (PIE) including non-destructive and destructive test is to be conducted to evaluate and characterize the nuclear performance. In this report, a principle of the examination equipment to measure and analyse fission gases existing nuclear fuels were described and features of the component and device consisting the fission gas measuring equipment are investigated. (author). 4 refs., 2 tabs., 6 figs.

  5. Low energy nuclear fission

    International Nuclear Information System (INIS)

    Nifenecker, H.

    1982-02-01

    In these lectures we present the liquid drop model of fission and compare some of its prediction with experiment. The liquid drop analogy allows to define in a rather simple and intuitive way a number of useful concepts and possible observables. We then discuss, using the example of the oscillator model, the generality of shell effects. We show how a synthesis of the liquid drop model and of the shell model can be made using the Strutinsky shell averaging procedure. Some experimental data related to the existence of shape isomers are presented and discussed. We conclude by discussing some aspects, both experimental and theoretical, of fission dynamics

  6. Low energy nuclear fission

    International Nuclear Information System (INIS)

    Nifenecker, H.

    1980-08-01

    In these lectures the liquid drop model of fission is presented and some of its predictions compared with experiment. The liquid drop analogy allows to define in a rather simple and intuitive way a number of useful concepts and possible observables. It is shown how a synthesis of the liquid drop model and of the shell model can be made using the Strutinsky shell averaging procedure. Some experimental data related to the existence of shape isomers are presented and discussed. We conclude by discussing some aspects, both experimental and theoretical, of fission dynamics

  7. Fission modelling with FIFRELIN

    Energy Technology Data Exchange (ETDEWEB)

    Litaize, Olivier; Serot, Olivier; Berge, Leonie [CEA, DEN, DER, SPRC, Saint Paul Lez Durance (France)

    2015-12-15

    The nuclear fission process gives rise to the formation of fission fragments and emission of particles (n,γ, e{sup -}). The particle emission from fragments can be prompt and delayed. We present here the methods used in the FIFRELIN code, which simulates the prompt component of the de-excitation process. The methods are based on phenomenological models associated with macroscopic and/or microscopic ingredients. Input data can be provided by experiment as well as by theory. The fission fragment de-excitation can be performed within Weisskopf (uncoupled neutron and gamma emission) or a Hauser-Feshbach (coupled neutron/gamma emission) statistical theory. We usually consider five free parameters that cannot be provided by theory or experiments in order to describe the initial distributions required by the code. In a first step this set of parameters is chosen to reproduce a very limited set of target observables. In a second step we can increase the statistics to predict all other fission observables such as prompt neutron, gamma and conversion electron spectra but also their distributions as a function of any kind of parameters such as, for instance, the neutron, gamma and electron number distributions, the average prompt neutron multiplicity as a function of fission fragment mass, charge or kinetic energy, and so on. Several results related to different fissioning systems are presented in this work. The goal in the next decade will be i) to replace some macroscopic ingredients or phenomenological models by microscopic calculations when available and reliable, ii) to be a support for experimentalists in the design of detection systems or in the prediction of necessary beam time or count rates with associated statistics when measuring fragments and emitted particle in coincidence iii) extend the model to be able to run a calculation when no experimental input data are available, iv) account for multiple chance fission and gamma emission before fission, v) account for

  8. Kinematic analysis of preterm newborns' spontaneous movements for postural activity assessment.

    Science.gov (United States)

    Halek, Jan; Muckova, Anita; Svoboda, Zdenek; Janura, Miroslav; Marikova, Jana; Horakova, Katerina; Kantor, Lumir; Nemcova, Nina

    2015-12-01

    The objectives of this pilot study were to assess the potential use of 3D videography for analyzing the motion of the body center of mass (COM) in newborns and to determine differences in spontaneous movements between preterm and full-term infants. The group comprised 10 preterm newborns (gestational age at birth between 26 and 37 weeks; birth weight 800 to 2960 g; gestational age at the time of examination 34 to 39 weeks) and 10 full-term infants (gestational week 38 to 41; birth weight 2810 to 4360 g). To determine the range of motion of the COM, 3D videography was used (2 cameras, 25 Hz). When recording their movements, the infants were in the supine position, calm and awake. The recordings were processed using the APAS software. Selected points on the body were marked to obtain data for calculating the basic parameters of COM trajectories. The range of motion of the COM in both craniocaudal and anteroposterior directions was significantly greater in premature infants (P preterm babies. This was also valid for the velocity of motion of the COM in the craniocaudal direction (P preterm infants. Basic kinematic characteristics of the motion of the COM (range, variability, velocity) are greater in preterm infants.

  9. Etiology of spontaneous pneumothorax in 105 HIV-infected patients without highly active antiretroviral therapy

    International Nuclear Information System (INIS)

    Rivero, Antonio; Perez-Camacho, Ines; Lozano, Fernando; Santos, Jesus; Camacho, Angela; Serrano, Ascencion; Cordero, Elisa; Jimenez, Francisco; Torres-Tortosa, Manuel; Torre-Cisneros, Julian

    2009-01-01

    Introduction: Spontaneous pneumothorax (SP) is a frequent complication in non-treated HIV-infected patients as a complication of opportunistic infections and tumours. Objective: To analyse the aetiology of SP in non-treated HIV patients. Patients and methods: Observational study of SP cases observed in a cohort of 9831 of non-treated HIV-infected patients attended in seven Spanish hospitals. Results: 105 patients (1.06%) developed SP. The aetiological cause was identified in 89 patients. The major causes identified were: bacterial pneumonia (36 subjects, 34.3%); Pneumocystis jiroveci pneumonia (PJP) (31 patients, 29.5%); and pulmonary tuberculosis (17 cases, 15.2%). The most common cause of SP in drugs users was bacterial pneumonia (40%), whereas PJP was more common (65%) in sexual transmitted HIV-patients. The most common cause of bilateral SP was PJP (62.5%) whereas unilateral SP was most commonly associated with bacterial pneumonia (40.2%). The most common cause of SP in patients with a CD4+ lymphocyte count >200 cells/ml and in patients without AIDS criteria was bacterial pneumonia. PJP was the more common cause in patients with a CD4+ lymphocyte count <200 cells/ml or with AIDS. Conclusion: The incidence of SP in non-treated HIV-infected patients was 1.06%. The aetiology was related to the patients risk practices and to their degree of immunosuppression. Bacterial pneumonia was the most common cause of SP.

  10. Synaptotagmin I regulates patterned spontaneous activity in the developing rat retina via calcium binding to the C2AB domains.

    Directory of Open Access Journals (Sweden)

    Chung-Wei Chiang

    Full Text Available BACKGROUND: In neonatal binocular animals, the developing retina displays patterned spontaneous activity termed retinal waves, which are initiated by a single class of interneurons (starburst amacrine cells, SACs that release neurotransmitters. Although SACs are shown to regulate wave dynamics, little is known regarding how altering the proteins involved in neurotransmitter release may affect wave dynamics. Synaptotagmin (Syt family harbors two Ca(2+-binding domains (C2A and C2B which serve as Ca(2+ sensors in neurotransmitter release. However, it remains unclear whether SACs express any specific Syt isoform mediating retinal waves. Moreover, it is unknown how Ca(2+ binding to C2A and C2B of Syt affects wave dynamics. Here, we investigated the expression of Syt I in the neonatal rat retina and examined the roles of C2A and C2B in regulating wave dynamics. METHODOLOGY/PRINCIPAL FINDINGS: Immunostaining and confocal microscopy showed that Syt I was expressed in neonatal rat SACs and cholinergic synapses, consistent with its potential role as a Ca(2+ sensor mediating retinal waves. By combining a horizontal electroporation strategy with the SAC-specific promoter, we specifically expressed Syt I mutants with weakened Ca(2+-binding ability in C2A or C2B in SACs. Subsequent live Ca(2+ imaging was used to monitor the effects of these molecular perturbations on wave-associated spontaneous Ca(2+ transients. We found that targeted expression of Syt I C2A or C2B mutants in SACs significantly reduced the frequency, duration, and amplitude of wave-associated Ca(2+ transients, suggesting that both C2 domains regulate wave temporal properties. In contrast, these C2 mutants had relatively minor effects on pairwise correlations over distance for wave-associated Ca(2+ transients. CONCLUSIONS/SIGNIFICANCE: Through Ca(2+ binding to C2A or C2B, the Ca(2+ sensor Syt I in SACs may regulate patterned spontaneous activity to shape network activity during development

  11. Contributions to the theory of fission neutron emission

    International Nuclear Information System (INIS)

    Seeliger, D.; Maerten, H.; Ruben, A.

    1990-03-01

    This report gives a compilation of recent work performed at Technical University, Dresden by D. Seeliger, H. Maerten and A. Ruben on the topic of fission neutron emission. In the first paper calculated fission neutron spectra are presented using the temperature distribution model FINESSE for fissioning actinide nuclei. In the second paper, starting from a general energy balance, Terrell's approach is generalized to describe average fragment energies as a function of incident energy; trends of fragment energy data in the Th-Pu region are well reproduced. In the third contribution, prompt fission neutron spectra and fragment characteristics for spontaneous fission of even Pu-isotopes are presented and discussed in comparison with experimental data using a phenomenological scission point model including temperature dependent shell effects. In the fourth paper, neutron multiplicities and energy spectra as well as average fragment energies for incident energies from threshold to 20 MeV (including multiple-chance fission) for U-238 are compared with traditional data representations. (author). Refs, figs and tabs

  12. Discoveries of isotopes by fission

    Indian Academy of Sciences (India)

    2015-08-28

    Aug 28, 2015 ... Of the about 3000 isotopes presently known, about 20% have been discovered in fission. The history of fission as it relates to the discovery of isotopes as well as the various reaction mechanisms leading to isotope discoveries involving fission are presented.

  13. 50 years of nuclear fission

    International Nuclear Information System (INIS)

    Hilscher, D.

    1989-01-01

    The article tells the story of the discovery of nuclear fission in Berlin 50 years ago by Otto Hahn and Fritz Strassmann in cooperation with Lise Meitner. 50 years later nuclear fission is still a subject of research. Some question remain unanswered. Selected new research results are used to discuss the dynamics of the collective movement of the elementary nuclear fission process. (orig.) [de

  14. Comparison Of 252Cf Time Correlated Induced Fisssion With AmLi Induced Fission On Fresh MTR Research Reactor Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Jay Prakash [Los Alamos National Laboratory

    2017-03-30

    The effective application of international safeguards to research reactors requires verification of spent fuel as well as fresh fuel. To accomplish this goal various nondestructive and destructive assay techniques have been developed in the US and around the world. The Advanced Experimental Fuel Counter (AEFC) is a nondestructive assay (NDA) system developed at Los Alamos National Laboratory (LANL) combining both neutron and gamma measurement capabilities. Since spent fuel assemblies are stored in water, the system was designed to be watertight to facilitate underwater measurements by inspectors. The AEFC is comprised of six 3He detectors as well as a shielded and collimated ion chamber. The 3He detectors are used for active and passive neutron coincidence counting while the ion chamber is used for gross gamma counting. Active coincidence measurement data is used to measure residual fissile mass, whereas the passive coincidence measurement data along with passive gamma measurement can provide information about burnup, cooling time, and initial enrichment. In the past, most of the active interrogation systems along with the AEFC used an AmLi neutron interrogation source. Owing to the difficulty in obtaining an AmLi source, a 252Cf spontaneous fission (SF) source was used during a 2014 field trail in Uzbekistan as an alternative. In this study, experiments were performed to calibrate the AEFC instrument and compare use of the 252Cf spontaneous fission source and the AmLi (α,n) neutron emission source. The 252Cf source spontaneously emits bursts of time-correlated prompt fission neutrons that thermalize in the water and induce fission in the fuel assembly. The induced fission (IF) neutrons are also time correlated resulting in more correlated neutron detections inside the 3He detector, which helps reduce the statistical errors in doubles when using the 252Cf interrogation source instead of

  15. Story of Fission

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 21; Issue 3. Story of Fission: Unlocking Power of the Nucleus. Amit Roy. General Article Volume 21 Issue 3 March 2016 pp 247-258. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/021/03/0247-0258 ...

  16. Story of Fission

    Indian Academy of Sciences (India)

    IAS Admin

    and contributes very little to global warming. The discovery of fission of uranium in 1939 changed forever the way society at large supported scientific research. Till that time, individual researchers or small groups would pursue their sub- jects of interest with whatever resources they could muster either from government or ...

  17. The discovery of fission

    International Nuclear Information System (INIS)

    McKay, H.A.C.

    1978-01-01

    In this article by the retired head of the Separation Processes Group of the Chemistry Division, Atomic Energy Research Establishment, Harwell, U.K., the author recalls what he terms 'an exciting drama, the unravelling of the nature of the atomic nucleus' in the years before the Second World War, including the discovery of fission. 12 references. (author)

  18. Study of spontaneous deposition of 210Po on various metals and application for activity assessment in cigarette smoke

    International Nuclear Information System (INIS)

    Karali, T.; Oelmez, S.; Yener, G.

    1996-01-01

    210 Po in environmental samples has been accumulated on various metals using the chemical electrodeposition technique. The 210 Po was deposited spontaneously on metal discs after decomposition of the sample in HCl acid and then measured using a ZnS(Ag)α-particle detector. Silver was observed to have the highest deposition efficiency when 210 Po deposition on different metals was studied. Copper discs were used in the application of activity assessment in cigarette smoke as this is more available and more economical although silver has a higher efficiency than that of other materials examined. The technique is applied for the analysis of 210 Po in tobacco, ash and butt for several brands of imported and domestic cigarettes smoked in Turkey. (Author)

  19. Regional homogeneity of spontaneous brain activity in adult patients with obsessive-compulsive disorder before and after cognitive behavioural therapy.

    Science.gov (United States)

    Yang, Xiang-Yun; Sun, Jing; Luo, Jia; Zhong, Zhao-Xi; Li, Ping; Yao, Shu-Min; Xiong, Hong-Fang; Huang, Fang-Fang; Li, Zhan-Jiang

    2015-12-01

    Cognitive behavioural therapy (CBT) is an effective treatment for obsessive-compulsive disorder (OCD). Several neuroimaging studies have explored alterations of brain function in OCD patients as they performed tasks after CBT. However, the effects of CBT on the neural activityin OCD during rest remain unknown. Therefore, we investigated changes in regional homogeneity (ReHo) in OCD patients before and after CBT. Twenty-two OCD patients and 22 well-matched healthy controls participated in the resting-state functional magnetic resonance imaging scans. We compared differences in ReHo between the OCD and control groups before treatment and investigated the changes of ReHo in 17 OCD patients who responded to CBT. Compared to healthy controls, OCD patients exhibited higher ReHo in the right orbitofrontal cortex (OFC), bilateral middle frontal cortex, right precuneus, left cerebellum, and vermis, as well as lower ReHo in the bilateral caudate, right calcarine, right posterior cingulate cortex, and right middle temporal cortex. Along with the clinical improvement in OCD patients after CBT, we found decreased ReHo in the right OFC, bilateral middle frontal cortex, left cerebellum and vermis, and increased ReHo in the left caudate. Improvement of OCD symptoms was significantly correlated with the changed ReHo in the right OFC and left cerebellum. Although these findings are preliminary and need to be replicated in larger samples, they indicate the presence of abnormal spontaneous brain activity of the prefrontal-striatal-cerebellar circuit in OCD patients, and provide evidence that CBT can selectively modulate the spontaneous brain activity of this circuit in OCD patients. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Spontaneous flow in polar active fluids: the effect of a phenomenological self propulsion-like term.

    Science.gov (United States)

    Bonelli, Francesco; Gonnella, Giuseppe; Tiribocchi, Adriano; Marenduzzo, Davide

    2016-01-01

    We present hybrid lattice Boltzmann simulations of extensile and contractile active fluids where we incorporate phenomenologically the tendency of active particles such as cell and bacteria, to move, or swim, along the local orientation. Quite surprisingly, we show that the interplay between alignment and activity can lead to completely different results, according to geometry (periodic boundary conditions or confinement between flat walls) and nature of the activity (extensile or contractile). An interesting generic outcome is that the alignment interaction can transform stationary active patterns into continuously moving ones: the dynamics of these evolving patterns can be oscillatory or chaotic according to the strength of the alignment term. Our results suggest that flow-polarisation alignment can have important consequences on the collective dynamics of active fluids and active gel.

  1. Population calcium imaging of spontaneous respiratory and novel motor activity in the facial nucleus and ventral brainstem in newborn mice.

    Science.gov (United States)

    Persson, Karin; Rekling, Jens C

    2011-05-15

    The brainstem contains rhythm and pattern forming circuits, which drive cranial and spinal motor pools to produce respiratory and other motor patterns. Here we used calcium imaging combined with nerve recordings in newborn mice to reveal spontaneous population activity in the ventral brainstem and in the facial nucleus. In Fluo-8AM loaded brainstem-spinal cord preparations, respiratory activity on cervical nerves was synchronized with calcium signals at the ventrolateral brainstem surface. Individual ventrolateral neurons at the level of the parafacial respiratory group showed perfect or partial synchrony with respiratory nerve bursts. In brainstem-spinal cord preparations, cut at the level of the mid-facial nucleus, calcium signals were recorded in the dorsal, lateral and medial facial subnuclei during respiratory activity. Strong activity initiated in the dorsal subnucleus, followed by activity in lateral and medial subnuclei. Whole-cell recordings from facial motoneurons showed weak respiratory drives, and electrical field potential recordings confirmed respiratory drive to particularly the dorsal and lateral subnuclei. Putative facial premotoneurons showed respiratory-related calcium signals, and were predominantly located dorsomedial to the facial nucleus. A novel motor activity on facial, cervical and thoracic nerves was synchronized with calcium signals at the ventromedial brainstem extending from the level of the facial nucleus to the medulla–spinal cord border. Cervical dorsal root stimulation induced similar ventromedial activity. The medial facial subnucleus showed calcium signals synchronized with this novel motor activity on cervical nerves, and cervical dorsal root stimulation induced similar medial facial subnucleus activity. In conclusion, the dorsal and lateral facial subnuclei are strongly respiratory-modulated, and the brainstem contains a novel pattern forming circuit that drives the medial facial subnucleus and cervical motor pools.

  2. Evaluation and compilation of fission product yields 1993

    International Nuclear Information System (INIS)

    England, T.R.; Rider, B.F.

    1995-01-01

    This document is the latest in a series of compilations of fission yield data. Fission yield measurements reported in the open literature and calculated charge distributions have been used to produce a recommended set of yields for the fission products. The original data with reference sources, and the recommended yields axe presented in tabular form. These include many nuclides which fission by neutrons at several energies. These energies include thermal energies (T), fission spectrum energies (F), 14 meV High Energy (H or HE), and spontaneous fission (S), in six sets of ten each. Set A includes U235T, U235F, U235HE, U238F, U238HE, Pu239T, Pu239F, Pu241T, U233T, Th232F. Set B includes U233F, U233HE, U236F, Pu239H, Pu240F, Pu241F, Pu242F, Th232H, Np237F, Cf252S. Set C includes U234F, U237F, Pu240H, U234HE, U236HE, Pu238F, Am241F, Am243F, Np238F, Cm242F. Set D includes Th227T, Th229T, Pa231F, Am241T, Am241H, Am242MT, Cm245T, Cf249T, Cf251T, Es254T. Set E includes Cf250S, Cm244S, Cm248S, Es253S, Fm254S, Fm255T, Fm256S, Np237H, U232T, U238S. Set F includes Cm243T, Cm246S, Cm243F, Cm244F, Cm246F, Cm248F, Pu242H, Np237T, Pu240T, and Pu242T to complete fission product yield evaluations for 60 fissioning systems in all. This report also serves as the primary documentation for the second evaluation of yields in ENDF/B-VI released in 1993

  3. Evaluation and compilation of fission product yields 1993

    Energy Technology Data Exchange (ETDEWEB)

    England, T.R.; Rider, B.F.

    1995-12-31

    This document is the latest in a series of compilations of fission yield data. Fission yield measurements reported in the open literature and calculated charge distributions have been used to produce a recommended set of yields for the fission products. The original data with reference sources, and the recommended yields axe presented in tabular form. These include many nuclides which fission by neutrons at several energies. These energies include thermal energies (T), fission spectrum energies (F), 14 meV High Energy (H or HE), and spontaneous fission (S), in six sets of ten each. Set A includes U235T, U235F, U235HE, U238F, U238HE, Pu239T, Pu239F, Pu241T, U233T, Th232F. Set B includes U233F, U233HE, U236F, Pu239H, Pu240F, Pu241F, Pu242F, Th232H, Np237F, Cf252S. Set C includes U234F, U237F, Pu240H, U234HE, U236HE, Pu238F, Am241F, Am243F, Np238F, Cm242F. Set D includes Th227T, Th229T, Pa231F, Am241T, Am241H, Am242MT, Cm245T, Cf249T, Cf251T, Es254T. Set E includes Cf250S, Cm244S, Cm248S, Es253S, Fm254S, Fm255T, Fm256S, Np237H, U232T, U238S. Set F includes Cm243T, Cm246S, Cm243F, Cm244F, Cm246F, Cm248F, Pu242H, Np237T, Pu240T, and Pu242T to complete fission product yield evaluations for 60 fissioning systems in all. This report also serves as the primary documentation for the second evaluation of yields in ENDF/B-VI released in 1993.

  4. Lunar surface fission power supplies: Radiation issues

    International Nuclear Information System (INIS)

    Houts, M.G.; Lee, S.K.

    1994-01-01

    A lunar space fission power supply shield that uses a combination of lunar regolith and materials brought from earth may be optimal for early lunar outposts and bases. This type of shield can be designed such that the fission power supply does not have to be moved from its landing configuration, minimizing handling and required equipment on the lunar surface. Mechanisms for removing heat from the lunar regolith are built into the shield, and can be tested on earth. Regolith activation is greatly reduced compared with a shield that uses only regolith, and it is possible to keep the thermal conditions of the fission power supply close to those seen in free space. For a well designed shield, the additional mass required to be brought from earth should be less than 1,000 kg. Detailed radiation transport calculations confirm the feasibility of such a shield

  5. Obsidian dating by fission track method

    International Nuclear Information System (INIS)

    Araya, A.M.O.

    1990-12-01

    The fission track method was employed to obtain the age of twelve obsidian sample from Ecuador. By using the plateau-age correction method, we obtained the true age of each sample and were able to identify four groups of ages in the studied area. Thereafter we studied the fading of fission tracks in two obsidian samples with different origins: Yanaurcu, Ecuador and Monte Arci, Italy. We constructed Arrhenius plots and calculated activation energies for both samples. The results from thermal annealing experiments were compared with theoretical curves obtained by integrating an equation proposed by Shukolyukov et al (1965). (author). 43 refs, 20 figs, 10 tabs

  6. Analytical evaluation of fission product sensitivities

    International Nuclear Information System (INIS)

    Sola, A.

    1977-01-01

    Evaluating the concentration of a fission product produced in a reactor requires the knowledge of a fairly large number of variables. Sensitivity studies were made to ascertain the important variables. Analytical formulae were developed sufficiently simple to allow numerical computations. Some simplified formulas are also given and they are applied to the following isotopes: 80 Se, 82 Se, 81 Br, 82 Br, 82 Kr, 83 Kr, 84 Kr, 85 Kr, 86 Kr. Their sensitivities to capture cross sections, fission yields, ratios of activation cross sections, half-lives (during and after irradiation), branching ratios, as well as to the neutron flux and to the time are considered

  7. Chronic baroreflex activation restores spontaneous baroreflex control and variability of heart rate in obesity-induced hypertension.

    Science.gov (United States)

    Iliescu, Radu; Tudorancea, Ionut; Irwin, Eric D; Lohmeier, Thomas E

    2013-10-01

    The sensitivity of baroreflex control of heart rate is depressed in subjects with obesity hypertension, which increases the risk for cardiac arrhythmias. The mechanisms are not fully known, and there are no therapies to improve this dysfunction. To determine the cardiovascular dynamic effects of progressive increases in body weight leading to obesity and hypertension in dogs fed a high-fat diet, 24-h continuous recordings of spontaneous fluctuations in blood pressure and heart rate were analyzed in the time and frequency domains. Furthermore, we investigated whether autonomic mechanisms stimulated by chronic baroreflex activation and renal denervation-current therapies in patients with resistant hypertension, who are commonly obese-restore cardiovascular dynamic control. Increases in body weight to ∼150% of control led to a gradual increase in mean arterial pressure to 17 ± 3 mmHg above control (100 ± 2 mmHg) after 4 wk on the high-fat diet. In contrast to the gradual increase in arterial pressure, tachycardia, attenuated chronotropic baroreflex responses, and reduced heart rate variability were manifest within 1-4 days on high-fat intake, reaching 130 ± 4 beats per minute (bpm) (control = 86 ± 3 bpm) and ∼45% and baroreflex activation and renal denervation abolished the hypertension. However, only baroreflex activation effectively attenuated the tachycardia and restored cardiac baroreflex sensitivity and heart rate variability. These findings suggest that baroreflex activation therapy may reduce the risk factors for cardiac arrhythmias as well as lower arterial pressure.

  8. To Take the Stairs or Not to Take the Stairs? Employing the Reflective–Impulsive Model to Predict Spontaneous Physical Activity

    Directory of Open Access Journals (Sweden)

    Marcos Daou

    2017-09-01

    Full Text Available The reflective–impulsive model (RIM has been employed to explain various health behaviors. The present study used RIM to predict a spontaneous physical activity behavior. Specifically, 107 participants (75 females; Mage = 20.6 years, SD = 1.92 years completed measures of (1 reflections about spontaneous physical activity, as indexed by self-report questionnaire; (2 impulse toward physical activity, as indexed by the manikin task; and (3 (state self-control, as indexed by the Stroop task. The dependent variable was whether participants took the stairs or the elevator to the study laboratory. Results revealed reflections toward spontaneous physical activity positively predicted stair-taking. Further, a significant impulse toward physical activity × self-control interaction was observed. This interaction revealed that participants with high self-control who had a high impulse toward PA were more likely to take the stairs than their counterparts with a low impulse toward PA, whereas the opposite was the case for participants with low self-control. However, the impulse × self-control interaction was not significant when employing a self-report measure of trait self-control. Thus, RIM may be a good framework with which to consider spontaneous physical activity, but careful consideration must be given when examining variables within RIM (e.g., the boundary condition of self-control.

  9. Spontaneous and cytokine induced expression and activity of matrix metalloproteinases in human colonic epithelium

    DEFF Research Database (Denmark)

    Pedersen, G; Saermark, T; Kirkegaard, T

    2009-01-01

    levels in cells from inflamed IBD mucosa. MMP-2 and -8 mRNA were expressed inconsistently and MMP-11, -13 and -14 mRNA undetectable. Proteolytic MMP activity was detected in CEC supernatants and the level was increased significantly in inflamed IBD epithelium. The enzyme activity was inhibited strongly...

  10. Spontaneous cluster activity in the inferior olivary nucleus in brainstem slices from postnatal mice

    DEFF Research Database (Denmark)

    Rekling, Jens C; Reveles Jensen, Kristian; Jahnsen, Henrik

    2012-01-01

    A distinctive property of the cerebellar system is olivocerebellar modules, where synchronized electrical activity in neurons in the inferior olivary nucleus (IO) evokes organized activity in the cerebellar cortex. However, the exact function of these modules, and how they are developed, is still...

  11. Status of measurements of fission neutron spectra of Minor Actinides

    Energy Technology Data Exchange (ETDEWEB)

    Drapchinsky, L.; Shiryaev, B. [V.G. Khlopin Radium Inst., Saint Petersburg (Russian Federation)

    1997-03-01

    The report considers experimental and theoretical works on studying the energy spectra of prompt neutrons emitted in spontaneous fission and neutron induced fission of Minor Actinides. It is noted that neutron spectra investigations were done for only a small number of such nuclei, most measurements, except those of Cf-252, having been carried out long ago by obsolete methods and imperfectapparatus. The works have no detailed description of experiments, analysis of errors, detailed numerical information about results of experiments. A conclusion is made that the available data do not come up to modern requirements. It is necessary to make new measurements of fission prompt neutron spectra of transuranium nuclides important for the objectives of working out a conception of minor actinides transmutation by means of special reactors. (author)

  12. Cold fission description with constant and varying mass asymmetries

    International Nuclear Information System (INIS)

    Duarte, S.B.; Rodriguez, O.; Tavares, O.A.P.; Goncalves, M.; Garcia, F.; Guzman, F.

    1998-01-01

    Different description for varying the mass asymmetry in the fragmentation process are used to calculate the cold fission barrier penetrability. The relevance of the appropriate choice for both the description of the pre-scission phase and inertia coefficient to unify alpha decay, cluster radioactivity, and spontaneous cold fission processes in the same theoretical framework is explicitly shown. We calculate the half-life of all possible partition modes of nuclei of A > 200 following the most recent Mass Table by Audi and Wapstra. It is shown that if one uses the description in which the mass asymmetry is maintained constant during the fragmentation process, the experimental half-life-values and mass yield of 234 U cold fission are satisfactorily reproduced. (author)

  13. Effect of distance vision and refractive error on the spontaneous eye blink activity in human subjects in primary eye gaze.

    Science.gov (United States)

    Doughty, Michael J

    2018-04-04

    To evaluate whether visual target character and visibility affects spontaneous eye blink rate (SEBR) in primary eye gaze and silence. Video recordings were made of young healthy adults who were either emmetropic (n=32) or who wore spectacles for refractive error (range -4.75D and +4.50D (n=31). Emmetropes had 5min recordings made whilst seated and looking towards a distant whiteboard. For spectacle wearers, recordings were made whilst looking towards the whiteboard with a 35mm sized cross, and repeated after spectacle removal. The average number of eye blinks over 5min was assessed, and its intra-subject variability as the coefficient of variation (COV). Over 5min without a distance target, an average SEBR of 10.4blinks/min was observed in emmetropes with a of COV=38.1%, and a significant increase in SEBR over the 5th minute to 13.6blinks/min. Hyperopes being asked to look towards a distant target showed the essentially same blinking rate of 11.1/min with or without spectacle wear with the intra-subject variability (COV) being 21.3%. Myopic subjects showed a slightly higher SEBR if looking towards a target without their spectacles (12.4 vs. 11.0blinks/min), with the COV being 18.8%. The studies indicate that some form of visual target could be useful to promote constancy of spontaneous eye blink activity over time, but that a distance visual target (when provided) does not need to be seen clearly. Crown Copyright © 2018. Published by Elsevier España, S.L.U. All rights reserved.

  14. MHC class I-restricted determinants on the glutamic acid decarboxylase 65 molecule induce spontaneous CTL activity.

    Science.gov (United States)

    Quinn, A; McInerney, M F; Sercarz, E E

    2001-08-01

    CD4(+) T cell responses to glutamic acid decarboxylase (GAD65) spontaneously arise in nonobese diabetic (NOD) mice before the onset of insulin-dependent diabetes mellitus (IDDM) and may be critical to the pathogenic process. However, since both CD4(+) and CD8(+) T cells are involved in autoimmune diabetes, we sought to determine whether GAD65-specific CD8(+) T cells were also present in prediabetic NOD mice and contribute to IDDM. To refine the analysis, putative K(d)-binding determinants that were proximal to previously described dominant Th determinants (206-220 and 524-543) were examined for their ability to elicit cytolytic activity in young NOD mice. Naive NOD spleen cells stimulated with GAD65 peptides 206-214 (p206) and 546-554 (p546) produced IFN-gamma and showed Ag-specific CTL responses against targets pulsed with homologous peptide. Conversely, several GAD peptides distal to the Th determinants, and control K(d)-binding peptides did not induce similar responses. Spontaneous CTL responses to p206 and p546 were mediated by CD8(+) T cells that are capable of lysing GAD65-expressing target cells, and p546-specific T cells transferred insulitis to NOD.scid mice. Young NOD mice pretreated with p206 and p546 showed reduced CTL responses to homologous peptides and a delay in the onset of IDDM. Thus, MHC class I-restricted responses to GAD65 may provide an inflammatory focus for the generation of islet-specific pathogenesis and beta cell destruction. This report reveals a potential therapeutic role for MHC class I-restricted peptides in treating autoimmune disease and revisits the notion that the CD4- and CD8-inducing determinants on some molecules may benefit from a proximal relationship.

  15. Correlation properties of spontaneous motor activity in healthy infants: a new computer-assisted method to evaluate neurological maturation.

    Science.gov (United States)

    Waldmeier, Sandra; Grunt, Sebastian; Delgado-Eckert, Edgar; Latzin, Philipp; Steinlin, Maja; Fuhrer, Katharina; Frey, Urs

    2013-06-01

    Qualitative assessment of spontaneous motor activity in early infancy is widely used in clinical practice. It enables the description of maturational changes of motor behavior in both healthy infants and infants who are at risk for later neurological impairment. These assessments are, however, time-consuming and are dependent upon professional experience. Therefore, a simple physiological method that describes the complex behavior of spontaneous movements (SMs) in infants would be helpful. In this methodological study, we aimed to determine whether time series of motor acceleration measurements at 40-44 weeks and 50-55 weeks gestational age in healthy infants exhibit fractal-like properties and if this self-affinity of the acceleration signal is sensitive to maturation. Healthy motor state was ensured by General Movement assessment. We assessed statistical persistence in the acceleration time series by calculating the scaling exponent α via detrended fluctuation analysis of the time series. In hand trajectories of SMs in infants we found a mean α value of 1.198 (95 % CI 1.167-1.230) at 40-44 weeks. Alpha changed significantly (p = 0.001) at 50-55 weeks to a mean of 1.102 (1.055-1.149). Complementary multilevel regression analysis confirmed a decreasing trend of α with increasing age. Statistical persistence of fluctuation in hand trajectories of SMs is sensitive to neurological maturation and can be characterized by a simple parameter α in an automated and observer-independent fashion. Future studies including children at risk for neurological impairment should evaluate whether this method could be used as an early clinical screening tool for later neurological compromise.

  16. Spontaneous deregulation

    NARCIS (Netherlands)

    Edelman, Benjamin; Geradin, Damien

    Platform businesses such as Airbnb and Uber have risen to success partly by sidestepping laws and regulations that encumber their traditional competitors. Such rule flouting is what the authors call “spontaneous private deregulation,” and it’s happening in a growing number of industries. The authors

  17. Fission rate sensitivities and fission fragment ranges for uranium and thorium-bearing materials irradiated with 252 Cf neutron source

    International Nuclear Information System (INIS)

    Moharram, B.M.

    2000-01-01

    The induced fission reactions of 235 U (n, f), 238 U (n,f) and 232 Th (n, f) based on the activation of natural uranium and thorium in samples with 252 Cf, neutron source, have been evaluated. The obtained results are the average of three samples from each test material (SRM 2710 Montana soil and Zirconia). The prepared samples have been configured in the so-called c ompensated - beam geometry i n which both gamma spectrometry jointly with solid state nuclear track detector techniques, revealed the fission rate sensitivity of 4.64 x 10 7 fission per gram per second per neutron (F.h 1 . S 1 .n 1 ), for zirconia as obtained by gamma activity arising from 134 I fission product (as a good monitor which is produced only from fissions), and the related value for SRM 2710 soil is 5.22 x 10 8 (F.g 1 S 1 .n 1 ). while the obtained values of the mean fission fragment ranges in SRM 2710 and zirconia as estimated from the fission track densities (by CR-39) and fission rates (by gamma spectrometry) are 3.97 x 10 3 g. cm 2 respectively which reveal good agreement with experiments and calculations done hitherto

  18. Spontaneous and cytokine induced expression and activity of matrix metalloproteinases in human colonic epithelium

    DEFF Research Database (Denmark)

    Pedersen, G; Saermark, T; Kirkegaard, T

    2009-01-01

    levels in cells from inflamed IBD mucosa. MMP-2 and -8 mRNA were expressed inconsistently and MMP-11, -13 and -14 mRNA undetectable. Proteolytic MMP activity was detected in CEC supernatants and the level was increased significantly in inflamed IBD epithelium. The enzyme activity was inhibited strongly......Matrix metalloproteinases (MMPs) have been implicated in tissue damage associated with inflammatory bowel disease (IBD).As the role of the intestinal epithelium in this process is unknown, we determined MMP expression and enzyme activity in human colonic epithelial cells (CEC). MMP mRNA expression...... was assessed by reverse transcription-polymerase chain reaction in HT-29 and DLD-1 cells and in CEC isolated from biopsies from IBD and control patients. Total MMP activity in the cells was measured by a functional assay, based on degradation of a fluorescent synthetic peptide containing the specific bond...

  19. High-efficiency electroluminescence and amplified spontaneous emission from a thermally activated delayed fluorescent near-infrared emitter

    Science.gov (United States)

    Kim, Dae-Hyeon; D'Aléo, Anthony; Chen, Xian-Kai; Sandanayaka, Atula D. S.; Yao, Dandan; Zhao, Li; Komino, Takeshi; Zaborova, Elena; Canard, Gabriel; Tsuchiya, Youichi; Choi, Eunyoung; Wu, Jeong Weon; Fages, Frédéric; Brédas, Jean-Luc; Ribierre, Jean-Charles; Adachi, Chihaya

    2018-02-01

    Near-infrared organic light-emitting diodes and semiconductor lasers could benefit a variety of applications including night-vision displays, sensors and information-secured displays. Organic dyes can generate electroluminescence efficiently at visible wavelengths, but organic light-emitting diodes are still underperforming in the near-infrared region. Here, we report thermally activated delayed fluorescent organic light-emitting diodes that operate at near-infrared wavelengths with a maximum external quantum efficiency of nearly 10% using a boron difluoride curcuminoid derivative. As well as an effective upconversion from triplet to singlet excited states due to the non-adiabatic coupling effect, this donor-acceptor-donor compound also exhibits efficient amplified spontaneous emission. By controlling the polarity of the active medium, the maximum emission wavelength of the electroluminescence spectrum can be tuned from 700 to 780 nm. This study represents an important advance in near-infrared organic light-emitting diodes and the design of alternative molecular architectures for photonic applications based on thermally activated delayed fluorescence.

  20. The fission track method

    International Nuclear Information System (INIS)

    Hansen, K.

    1990-01-01

    During the last decade fission track (FT) analysis has evolved as an important tool in exploration for hydrocarbon resources. Most important is this method's ability to yield information about temperatures at different times (history), and thus relate oil generation and time independently of other maturity parameters. The purpose of this paper is to introduce the basics of the method and give an example from the author's studies. (AB) (14 refs.)

  1. Preictal activity of subicular, CA1, and dentate gyrus principal neurons in the dorsal hippocampus before spontaneous seizures in a rat model of temporal lobe epilepsy.

    Science.gov (United States)

    Fujita, Satoshi; Toyoda, Izumi; Thamattoor, Ajoy K; Buckmaster, Paul S

    2014-12-10

    Previous studies suggest that spontaneous seizures in patients with temporal lobe epilepsy might be preceded by increased action potential firing of hippocampal neurons. Preictal activity is potentially important because it might provide new opportunities for predicting when a seizure is about to occur and insight into how spontaneous seizures are generated. We evaluated local field potentials and unit activity of single, putative excitatory neurons in the subiculum, CA1, CA3, and dentate gyrus of the dorsal hippocampus in epileptic pilocarpine-treated rats as they experienced spontaneous seizures. Average action potential firing rates of neurons in the subiculum, CA1, and dentate gyrus, but not CA3, increased significantly and progressively beginning 2-4 min before locally recorded spontaneous seizures. In the subiculum, CA1, and dentate gyrus, but not CA3, 41-57% of neurons displayed increased preictal activity with significant consistency across multiple seizures. Much of the increased preictal firing of neurons in the subiculum and CA1 correlated with preictal theta activity, whereas preictal firing of neurons in the dentate gyrus was independent of theta. In addition, some CA1 and dentate gyrus neurons displayed reduced firing rates preictally. These results reveal that different hippocampal subregions exhibit differences in the extent and potential underlying mechanisms of preictal activity. The finding of robust and significantly consistent preictal activity of subicular, CA1, and dentate neurons in the dorsal hippocampus, despite the likelihood that many seizures initiated in other brain regions, suggests the existence of a broader neuronal network whose activity changes minutes before spontaneous seizures initiate. Copyright © 2014 the authors 0270-6474/14/3416671-17$15.00/0.

  2. Vibroacustic microvibrations enhance kidney blood supply, glomerular filtration and glutathione peroxidase activity in spontaneously hypertensive rats.

    Science.gov (United States)

    Miloradović, Zoran; Mihailović-Stanojević, Nevena; Jovović, Đurđica; Ivanov, Milan; Vajić, Una J; Karanović, Danijela; Grujić Milanović, Jelica

    2015-01-01

    Limited numbers of studies include research of microvibration therapy in experimental models. We examined effects of chronic vibroacustic-microvibration treatment on haemodynamics and anti-oxidative defense in experimental hypertension. Study was performed on chronically treated hypertensive and normotensive Wistar rats. Mean arterial pressure (MAP), cardiac output (CO), renal blood flow (RBF), glomerular filtration and activity of anti-oxidative enzymes were determined after three weeks treatment. Vibroacustic treatment had no influence on MAP and CO, but RBF was increased in both groups of treated rats. Additionally, vibroacustic treatment enhanced diuresis and increased glomerular filtration in hypertensive rats. Glutathione peroxidase (GSH-Px) activity was elevated in both treated rat strains, but activity of superoxide dismutase was unchanged. We conclude that microvibration treatment doesn't ameliorate hypertension but improves renal blood supply (trough diminished renal vascular resistance), glomerular filtration, diuresis, and enhances glutathione dependent anti-oxidant defense with more important beneficials in hypertensive animals.

  3. [Fission product yields of 60 fissioning reactions]. Final report

    International Nuclear Information System (INIS)

    Rider, B.F.

    1995-01-01

    In keeping with the statement of work, I have examined the fission product yields of 60 fissioning reactions. In co-authorship with the UTR (University Technical Representative) Talmadge R. England ''Evaluation and Compilation of Fission Product Yields 1993,'' LA-UR-94-3106(ENDF-349) October, (1994) was published. This is an evaluated set of fission product Yields for use in calculation of decay heat curves with improved accuracy has been prepared. These evaluated yields are based on all known experimental data through 1992. Unmeasured fission product yields are calculated from charge distribution, pairing effects, and isomeric state models developed at Los Alamos National Laboratory. The current evaluation has been distributed as the ENDF/B-VI fission product yield data set

  4. Beta-delayed fission probabilities of transfermium nuclei, involved in the r-process

    International Nuclear Information System (INIS)

    Panov, I; Lutostansky, Yu; Thielemann, F-K

    2016-01-01

    For the nucleosynthesis of heavy and superheavy nuclei fission becomes very important when the r-process runs in a very high neutron density environment. In part, fission is responsible for the formation of heavy nuclei due to the inclusion of fission products as new seed nuclei (fission cycling). More than that, beta-delayed fission, along with spontaneous fission, is responsible in the late stages of the r-process for the suppression of superheavy element yields.For beta-delayed fission probability calculations a model description of the beta-strength- functions is required. Extended theoretical predictions for astro-physical applications were provided long ago, and new predictions also for superheavy nuclei with uptodate nuclear input are needed. For the further extension of data to heavier transactinides the models of strength- functions should be modified, taking into account more complicated level schemes. In our present calculations the strength-function model is based on the quasi-particle approximation of Finite Fermi Systems Theory.The probabilities of beta-delayed fission and beta-delayed neutron emission are calculated for some transfermium neutron-rich nuclei, and the influence of beta-delayed fission upon superheavy element formation is discussed. (paper)

  5. Effect of Imperatorin on the Spontaneous Motor Activity of Rat Isolated Jejunum Strips

    Directory of Open Access Journals (Sweden)

    Marta Mendel

    2015-01-01

    Full Text Available Imperatorin, a psoralen-type furanocoumarin, is a potent myorelaxant agent acting as a calcium antagonist on vascular smooth muscle. Its effects on other types of smooth muscle remain unknown. Therefore, the aim of this study was to investigate the hypothesized myorelaxant effect of imperatorin on gut motor activity and, possibly, to define the underlying mechanism of action. Imperatorin was made available for pharmacological studies from the fruits of the widely available Angelica officinalis through the application of high-performance countercurrent chromatography (HPCCC. Imperatorin generated reversible relaxation of jejunum strips dose-dependently (1–100 μM. At 25 and 50 μM, imperatorin caused relaxation comparable to the strength of the reaction induced by isoproterenol (Isop at 0.1 μM. The observed response resulted neither from the activation of soluble guanylate cyclase, nor from β-adrenoreceptor involvement, nor from Ca2+-activated potassium channels. Imperatorin relaxed intestine strips precontracted with high potassium concentration, attenuated the force and duration of K+-induced contractions, and modulated the response of jejunum strips to acetylcholine. The results suggest that imperatorin probably interacts with various Ca2+ influx pathways in intestine smooth muscle. The types of some calcium channels involved in the activity of imperatorin will be examined in a subsequent study.

  6. Spontaneous Brain Activity Did Not Show the Effect of Violent Video Games on Aggression: A Resting-State fMRI Study

    Directory of Open Access Journals (Sweden)

    Wei Pan

    2018-01-01

    Full Text Available A great many of empirical researches have proved that longtime exposure to violent video game can lead to a series of negative effects. Although research has focused on the neural basis of the correlation between violent video game and aggression, little is known whether the spontaneous brain activity is associated with violent video game exposure. To address this question, we measured the spontaneous brain activity using resting-state functional magnetic resonance imaging (fMRI. We used the amplitude of low-frequency fluctuations (ALFF and fractional ALFF (fALFF to quantify spontaneous brain activity. The results showed there is no significant difference in ALFF, or fALFF, between violent video game group and the control part, indicating that long time exposure to violent video games won’t significantly influence spontaneous brain activity, especially the core brain regions such as execution control, moral judgment and short-term memory. This implies the adverse impact of violent video games is exaggerated.

  7. Spontaneous Brain Activity Did Not Show the Effect of Violent Video Games on Aggression: A Resting-State fMRI Study.

    Science.gov (United States)

    Pan, Wei; Gao, Xuemei; Shi, Shuo; Liu, Fuqu; Li, Chao

    2017-01-01

    A great many of empirical researches have proved that longtime exposure to violent video game can lead to a series of negative effects. Although research has focused on the neural basis of the correlation between violent video game and aggression, little is known whether the spontaneous brain activity is associated with violent video game exposure. To address this question, we measured the spontaneous brain activity using resting-state functional magnetic resonance imaging (fMRI). We used the amplitude of low-frequency fluctuations (ALFF) and fractional ALFF (fALFF) to quantify spontaneous brain activity. The results showed there is no significant difference in ALFF, or fALFF, between violent video game group and the control part, indicating that long time exposure to violent video games won't significantly influence spontaneous brain activity, especially the core brain regions such as execution control, moral judgment and short-term memory. This implies the adverse impact of violent video games is exaggerated.

  8. THE EFFECT OF SOME ALPHA-ADRENOCEPTOR ANTAGONISTS ON SPONTANEOUS MYOGENIC ACTIVITY IN THE RAT PORTAL-VEIN AND THE PUTATIVE INVOLVEMENT OF ATP-SENSITIVE K+ CHANNELS

    NARCIS (Netherlands)

    SCHWIETERT, R; WILHELM, D; WILFFERT, B; VANZWIETEN, PA

    1992-01-01

    In the present study we showed that the alpha-adrenoceptor antagonists phentolamine, yohimbine, prazosin, corynanthine and idazoxan, when cumulatively applied in high concentrations (1-100-mu-mol/l), can increase spontaneous myogenic activity in the rat portal vein. 5-Methyl-urapidil and rauwolscine

  9. The effect of some α-adrenoceptor antagonists on spontaneous myogenic activity in the rat portal vein and the putative involvement of ATP-sensitive K+channels

    NARCIS (Netherlands)

    Schwietert, R.; Wilhelm, D.; Wilffert, B.; Van Zwieten, P.A.

    1992-01-01

    In the present study we showed that the α-adrenoceptor antagonists phentolamine, yohimbine, prazosin, corynanthine and idazoxan, when cumulatively applied in high concentrations (1-100 μmol/l), can increase spontaneous myogenic activity in the rat portal vein. 5-Methyl-urapidil and rauwolscine were

  10. Altered spontaneous activity of posterior cingulate cortex and superior temporal gyrus are associated with a smoking cessation treatment outcome using varenicline revealed by regional homogeneity.

    Science.gov (United States)

    Wang, Chao; Shen, Zhujing; Huang, Peiyu; Qian, Wei; Yu, Xinfeng; Sun, Jianzhong; Yu, Hualiang; Yang, Yihong; Zhang, Minming

    2017-06-01

    Compared to nonsmokers, smokers exhibit a number of potentially important differences in regional brain function. However, little is known about the associations between the local spontaneous brain activity and smoking cessation treatment outcomes. In the present analysis, we aimed to evaluate whether the local features of spontaneous brain activity prior to the target quit date was associated with the smoking cessation outcomes. All the participants underwent magnetic resonance imaging scans and smoking-related behavioral assessments. After a 12-week treatment with varenicline, 23 smokers succeeded in quitting smoking and 32 failed. Smokers underwent functional magnetic resonance imaging (fMRI) scanning prior to an open label smoking cessation treatment trial. Regional homogeneity (ReHo) was used to measure spontaneous brain activity, and whole-brain voxel-wise comparisons of ReHo were performed to detect brain regions with altered spontaneous brain activity between relapser and quitter groups. After controlling for potentially confounding factors including years of education, years smoked, cigarettes smoked per day and FTND score as covariates, compared to quitters, relapsers displayed significantly decreased ReHo in bilateral posterior cingulate cortex (PCC), as well as increased ReHo in left superior temporal gyrus (STG). These preliminary results suggest that regional brain function variables may be promising predictors of smoking relapse. This study provided novel insights into the neurobiological mechanisms underlying smoking relapse. A deeper understanding of the neurobiological mechanisms associated with relapse may result in novel pharmacological and behavioral interventions.

  11. The activity of spontaneous action potentials in developing hair cells is regulated by Ca(2+-dependence of a transient K+ current.

    Directory of Open Access Journals (Sweden)

    Snezana Levic

    Full Text Available Spontaneous action potentials have been described in developing sensory systems. These rhythmic activities may have instructional roles for the functional development of synaptic connections. The importance of spontaneous action potentials in the developing auditory system is underpinned by the stark correlation between the time of auditory system functional maturity, and the cessation of spontaneous action potentials. A prominent K(+ current that regulates patterning of action potentials is I(A. This current undergoes marked changes in expression during chicken hair cell development. Although the properties of I(A are not normally classified as Ca(2+-dependent, we demonstrate that throughout the development of chicken hair cells, I(A is greatly reduced by acute alterations of intracellular Ca(2+. As determinants of spike timing and firing frequency, intracellular Ca(2+ buffers shift the activation and inactivation properties of the current to more positive potentials. Our findings provide evidence to demonstrate that the kinetics and functional expression of I(A are tightly regulated by intracellular Ca(2+. Such feedback mechanism between the functional expression of I(A and intracellular Ca(2+ may shape the activity of spontaneous action potentials, thus potentially sculpting synaptic connections in an activity-dependent manner in the developing cochlea.

  12. Spontaneous Activity Associated with Delusions of Schizophrenia in the Left Medial Superior Frontal Gyrus: A Resting-State fMRI Study.

    Directory of Open Access Journals (Sweden)

    Bin Gao

    Full Text Available Delusions of schizophrenia have been found to be associated with alterations of some brain regions in structure and task-induced activation. However, the relationship between spontaneously occurring symptoms and spontaneous brain activity remains unclear. In the current study, 14 schizophrenic patients with delusions and 14 healthy controls underwent a resting-state functional magnetic resonance imaging (RS-fMRI scan. Patients with delusions of schizophrenia patients were rated with Positive and Negative Syndrome Scale (PANSS and Characteristics of Delusional Rating Scale (CDRS. Regional homogeneity (ReHo was calculated to measure the local synchronization of the spontaneous activity in a voxel-wise way. A two-sample t-test showed that ReHo of the right anterior cingulate gyrus and left medial superior frontal gyrus were higher in patients, and ReHo of the left superior occipital gyrus was lower, compared to healthy controls. Further, among patients, correlation analysis showed a significant difference between delusion scores of CRDS and ReHo of brain regions. ReHo of the left medial superior frontal gyrus was negatively correlated with patients' CDRS scores but not with delusional PANSS scores. These results suggested that altered local synchronization of spontaneous brain activity may be related to the pathophysiology of delusion in schizophrenia.

  13. Spontaneous Brain Activity Did Not Show the Effect of Violent Video Games on Aggression: A Resting-State fMRI Study

    Science.gov (United States)

    Pan, Wei; Gao, Xuemei; Shi, Shuo; Liu, Fuqu; Li, Chao

    2018-01-01

    A great many of empirical researches have proved that longtime exposure to violent video game can lead to a series of negative effects. Although research has focused on the neural basis of the correlation between violent video game and aggression, little is known whether the spontaneous brain activity is associated with violent video game exposure. To address this question, we measured the spontaneous brain activity using resting-state functional magnetic resonance imaging (fMRI). We used the amplitude of low-frequency fluctuations (ALFF) and fractional ALFF (fALFF) to quantify spontaneous brain activity. The results showed there is no significant difference in ALFF, or fALFF, between violent video game group and the control part, indicating that long time exposure to violent video games won’t significantly influence spontaneous brain activity, especially the core brain regions such as execution control, moral judgment and short-term memory. This implies the adverse impact of violent video games is exaggerated. PMID:29375416

  14. Reduction of circulating annexin A5 levels and resistance to annexin A5 anticoagulant activity in women with recurrent spontaneous pregnancy losses.

    NARCIS (Netherlands)

    Rand, J.H.; Arslan, A.A.; Wu, X.X.; Wein, R.; Mulholland, J.; Shah, M.; Heerde, W.L. van; Reutelingsperger, C.P.M.; Lockwood, C.J.; Kuczynski, E.

    2006-01-01

    OBJECTIVE: We investigated whether levels of annexin A5, evidence for resistance to annexin A5 activity, and levels anti-annexin A5 antibodies might be altered in women with a history of recurrent spontaneous pregnancy losses. STUDY DESIGN: These annexin A5 parameters were assayed in 70 nonpregnant

  15. Use of scripts and script-fading procedures and activity schedules to develop spontaneous social interaction in a three-year-old girl with autism

    Directory of Open Access Journals (Sweden)

    Anna Budzińska

    2014-05-01

    Full Text Available Autism entails serious deficiencies in communication and social behaviors. Individuals with autism, even those who have received intensive language intervention, are often viewed as lacking spontaneous language. In addition, some children with autism lack the ability of spontaneously seeking to share enjoyment, interests, or achievements with other people (e.g., a lack of showing, bringing, or pointing out objects of interest to other people. The aim of the study was to use ABA teaching techniques such as script and script fading procedure and activity schedule to teach three-year-old girl with autism spontaneous social interaction and shape joint attention skills. The result shows that ABA techniques were very effective in teaching many verbal skills such as answering questions, making requests, initiating conversation and asking question. Comparison made after implemented teaching procedure shows her initiating of joint attention skill (IJA is at the appropriate level for her age.

  16. Novel Target for Ameliorating Pain and Other Problems after SCI: Spontaneous Activity in Nociceptors

    Science.gov (United States)

    2016-06-01

    neurons within pain pathways and thus their electrical activity leads to the conscious sensation of pain as well associated reflex responses. These...promote pain sensations , and so it was not surprising to find that this chronic nociceptor SA was closely correlated with behavioral measures of pain...similar to those underlying long-term memory in the brain, such as late-phase long-term synaptic potentiation (LTP) (Asiedu et al., 2011; Laferriere et

  17. Bioactive compounds and antioxidant activity of Rosa canina L. biotypes from spontaneous flora of Transylvania.

    Science.gov (United States)

    Roman, Ioana; Stănilă, Andreea; Stănilă, Sorin

    2013-04-23

    The theoretical, but especially the practical values of identifying the biochemical compounds from the Rosa canina L. fruits are of present interest, this aspect being illustrated by the numerous researches. It was reported that the Rosa canina L. fruit, with its high ascorbic acid, phenolics and flavonoids contents, have antioxidant, antimutagenic and anticarcinogenic effects.This study was performed on order to evaluate the amount of the main phytochemicals (vitamin C, total polyphenols, and total flavonoids) content and their antioxidant activity. The results obtained revealed that the average amounts of vitamin C within the studied genotypes were: 360.22 mg/100 g frozen pulp (var. transitoria f. ramosissima, altitude 1250 m) and 112.20 mg/100 g frozen pulp (var. assiensis, altitude 440 m), giving a good correlation between the vitamin C content of the rosehip and the altitude. The total polyphenols content varied from 575 mg/100 g frozen pulp (var. transitoria f. ramosissima) to 326 mg/100 g frozen pulp (var. lutetiana f. fallens). The total flavonoids content showed the highest value for var. assiensis variant 163.3 mg/100 g frozen pulp and the lowest value attributed to var. transitoria f. montivaga 101.3 mg/100 g frozen pulp. The antioxidant activity of eight rose hip extracts from wild Transylvania populations was investigated through DPPH method. The antioxidant activity revealed a good correlation only with vitamin C content and total polyphenols. Eight Rose hip fruit species were compared taking into consideration the ascorbic acid, total polyphenols, total flavonoids contents and their antioxidant activity. Based on these results, two of the rosehip genotypes that were analysed could be of perspective for these species' amelioration, due to their content of phytochemicals mentioned above. These varieties are var. transitoria f. ramosissima (Bistrita-Nasaud, Agiesel) and var. transitoria f. montivaga (Bistrita-Nasaud, Salva) which can be used as a

  18. Status of the general description of fission observables by the GEF code

    CERN Document Server

    Jurado, B

    2014-01-01

    The GEneral Fission (GEF) model treats spontaneous fission and fission up to an excitation energy of about 100 MeV of a wide range of heavy nuclei. GEF makes use of general laws of statistical and quantum mechanics, assuring a high predictive power. It is unique in providing a general description of essentially all fission observables in a consistent way while preserving the correlations between all of them. In this contribution we present some of the physical aspects on which the model is based, give an overview on the results that can be obtained with the code and show an example that illustrates how the GEF code can serve as a framework for revealing the sensitivity of the fission observables to some basic nuclear properties.

  19. The Tubulation Activity of a Fission Yeast F-BAR Protein Is Dispensable for Its Function in Cytokinesis

    Directory of Open Access Journals (Sweden)

    Nathan A. McDonald

    2016-01-01

    Full Text Available F-BAR proteins link cellular membranes to the actin cytoskeleton in many biological processes. Here we investigated the function of the Schizosaccharomyces pombe Imp2 F-BAR domain in cytokinesis and find that it is critical for Imp2’s role in contractile ring constriction and disassembly. To understand mechanistically how the F-BAR domain functions, we determined its structure, elucidated how it interacts with membranes, and identified an interaction between dimers that allows helical oligomerization and membrane tubulation. Using mutations that block either membrane binding or tubulation, we find that membrane binding is required for Imp2’s cytokinetic function but that oligomerization and tubulation, activities often deemed central to F-BAR protein function, are dispensable. Accordingly, F-BARs that do not have the capacity to tubulate membranes functionally substitute for the Imp2 F-BAR, establishing that its major role is as a cell-cycle-regulated bridge between the membrane and Imp2 protein partners, rather than as a driver of membrane curvature.

  20. Are spontaneous conformational interconversions a molecular basis for long-period oscillations in enzyme activity?

    Science.gov (United States)

    Queiroz-Claret, C; Valon, C; Queiroz, O

    1988-01-01

    An unconventional hypothesis to the molecular basis of enzyme rhythms is that the intrinsic physical instability of the protein molecules which, in an aqueous medium, tend to move continuously from one conformational state to another could lead, in the population of enzyme molecules, to sizeable long-period oscillations in affinity for substrate and sensitivity to ligands and regulatory effects. To investigate this hypothesis, malate dehydrogenase was extracted and purified from leaves of the plant Kalanchoe blossfeldiana. The enzyme solutions were maintained under constant conditions and sampled at regular intervals for up to 40 or 70 h for measurements of activity as a function of substrate concentration, Km for oxaloacetic acid and sensitivity to the action of 2,3-butanedione, a modifier of active site arginyl residues. The results show that continuous slow oscillations in the catalytic capacity of the enzyme occur in all the extracts checked, together with fluctuations in Km. Apparent circadian periodicities were observed in accordance with previous data established during long run (100 h) experiments. The saturation curves for substrate showed multiple kinetic functions, with various pronounced intermediary plateaus and "bumps" depending on the time of sampling. Variation in the response to the effect of butanedione indicated fluctuation in the accessibility to the active site. Taken together, the results suggest that, under constant conditions, the enzyme in solution shifts continuously and reversibly between different configurations. This was confirmed by parallel studies on the proton-NMR spectrum of water aggregates in the enzyme solution and proton exchange rates.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Differential effect of central command on aortic and carotid sinus baroreceptor-heart rate reflexes at the onset of spontaneous, fictive motor activity.

    Science.gov (United States)

    Matsukawa, Kanji; Ishii, Kei; Kadowaki, Akito; Liang, Nan; Ishida, Tomoko

    2012-08-15

    Our laboratory has reported that central command blunts the sensitivity of the aortic baroreceptor-heart rate (HR) reflex at the onset of voluntary static exercise in conscious cats and spontaneous contraction in decerebrate cats. The purpose of this study was to examine whether central command attenuates the sensitivity of the carotid sinus baroreceptor-HR reflex at the onset of spontaneous, fictive motor activity in paralyzed, decerebrate cats. We confirmed that aortic nerve (AN)-stimulation-induced bradycardia was markedly blunted to 26 ± 4.4% of the control (21 ± 1.3 beats/min) at the onset of spontaneous motor activity. Although the baroreflex bradycardia by electrical stimulation of the carotid sinus nerve (CSN) was suppressed (P activity was much weaker (P abdominal aorta was blunted to 36% of the control (36 ± 1.6 beats/min) during spontaneous motor activity, suggesting that central command is able to inhibit the cardiomotor sensitivity of arterial baroreflexes as the net effect. Mechanical stretch of the triceps surae muscle never affected the baroreflex bradycardia elicited by AN or CSN stimulation and by aortic occlusion, suggesting that muscle mechanoreflex did not modify the cardiomotor sensitivity of aortic and carotid sinus baroreflex. Since the inhibitory effect of central command on the carotid baroreflex pathway, associated with spontaneous motor activity, was much weaker compared with the aortic baroreflex pathway, it is concluded that central command does not force a generalized modulation on the whole pathways of arterial baroreflexes but provides selective inhibition for the cardiomotor component of the aortic baroreflex.

  2. Characteristics of prompt fission gamma-ray emission - Experimental results and predictions

    International Nuclear Information System (INIS)

    Oberstedt, Andreas; Billnert, Robert; Oberstedt, Stephan

    2014-01-01

    Systematics from 2001, describing prompt fission gamma-ray spectra (PFGS) characteristics as function of mass and atomic number of the fissioning system, has been revisited and parameters have been revised based on recent experimental results. Although originally expressed for spontaneous and thermal neutron-induced fission, validity for fast neutrons was assumed and applied to predict PFGS characteristics for the reaction n + 238 U up to incident neutron energies of E n = 20 MeV. The results from this work are in good agreement with corresponding results from both model calculations and experiments. (authors)

  3. Spontaneous brain activity and EEG microstates. A novel EEG/fMRI analysis approach to explore resting-state networks.

    Science.gov (United States)

    Musso, F; Brinkmeyer, J; Mobascher, A; Warbrick, T; Winterer, G

    2010-10-01

    The brain is active even in the absence of explicit input or output as demonstrated from electrophysiological as well as imaging studies. Using a combined approach we measured spontaneous fluctuations in the blood oxygen level dependent (BOLD) signal along with electroencephalography (EEG) in eleven healthy subjects during relaxed wakefulness (eyes closed). In contrast to other studies which used the EEG frequency information to guide the functional MRI (fMRI) analysis, we opted for transient EEG events, which identify and quantify brain electric microstates as time epochs with quasi-stable field topography. We then used this microstate information as regressors for the BOLD fluctuations. Single trial EEGs were segmented with a specific module of the LORETA (low resolution electromagnetic tomography) software package in which microstates are represented as normalized vectors constituted by scalp electric potentials, i.e., the related 3-dimensional distribution of cortical current density in the brain. Using the occurrence and the duration of each microstate, we modeled the hemodynamic response function (HRF) which revealed BOLD activation in all subjects. The BOLD activation patterns resembled well known resting-state networks (RSNs) such as the default mode network. Furthermore we "cross validated" the data performing a BOLD independent component analysis (ICA) and computing the correlation between each ICs and the EEG microstates across all subjects. This study shows for the first time that the information contained within EEG microstates on a millisecond timescale is able to elicit BOLD activation patterns consistent with well known RSNs, opening new avenues for multimodal imaging data processing. Copyright 2010. Published by Elsevier Inc.

  4. Effects of voluntary exercise on spontaneous physical activity and food consumption in mice: Results from an artificial selection experiment.

    Science.gov (United States)

    Copes, Lynn E; Schutz, Heidi; Dlugosz, Elizabeth M; Acosta, Wendy; Chappell, Mark A; Garland, Theodore

    2015-10-01

    We evaluated the effect of voluntary exercise on spontaneous physical activity (SPA) and food consumption in mice from 4 replicate lines bred for 57 generations for high voluntary wheel running (HR) and from 4 non-selected control (C) lines. Beginning at ~24 days of age, mice were housed in standard cages or in cages with attached wheels. Wheel activity and SPA were monitored in 1-min intervals. Data from the 8th week of the experiment were analyzed because mice were sexually mature and had plateaued in body mass, weekly wheel running distance, SPA, and food consumption. Body mass, length, and masses of the retroperitoneal fat pad, liver, and heart were recorded after the 13th week. SPA of both HR and C mice decreased with wheel access, due to reductions in both duration and average intensity of SPA. However, total activity duration (SPA+wheel running; min/day) was ~1/3 greater when mice were housed with wheels, and food consumption was significantly increased. Overall, food consumption in both HR and C mice was more strongly affected by wheel running than by SPA. Duration of wheel running had a stronger effect than average speed, but the opposite was true for SPA. With body mass as a covariate, chronic wheel access significantly reduced fat pad mass and increased heart mass in both HR and C mice. Given that both HR and C mice housed with wheels had increased food consumption, the energetic cost of wheel running was not fully compensated by concomitant reductions in SPA. The experiment demonstrates that both duration and intensity of both wheel running and SPA were significant predictors of food consumption. This sort of detailed analysis of the effects of different aspects of physical activity on food consumption has not previously been reported for a non-human animal, and it sets the stage for longitudinal examination of energy balance and its components in rodent models. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Nuclear structure via isomer tagging of fission fragments

    Science.gov (United States)

    Wu, C. Y.; Cline, D.; Simon, M. W.; Stoyer, M. A.

    1997-10-01

    The high efficiency for detecting high-fold γ rays by large Ge arrays makes it possible to study the detailed spectroscopy of many neutron-rich nuclei produced by fission. Major progress has been made using sealed spontaneous fission sources. Considerable improvement in selectivity is provided, with an open source, both by gating on isomers and by detection of both fission fragments in coincidence with the deexcitation γ rays (see the preceding contribution). The reconstructed kinematics allows a measure of fragment mass and the Doppler shift correction of γ rays. In a recent experiment, fission fragments were detected using half of the CHICO array and an annular PPAC in coincidence with deexcitation γ rays detected by the Rochester array of eight Compton-suppressed Ge detectors. The annular PPAC was located only 1.0" from a 3.7 μCi ^252Cf source for efficient isomer tagging. The correlation was studied between delayed, within a time window between 150 ns and 10 μs after a fission occurring, and prompt γ rays. Several prominent feeding patterns to isomers in the mass region around 100 and 130 are identified by such correlation study. Experimental details and results will be presented.

  6. Essential Oil Composition, Antioxidant, Cytotoxic and Antiviral Activities of Teucrium pseudochamaepitys Growing Spontaneously in Tunisia

    Directory of Open Access Journals (Sweden)

    Saoussen Hammami

    2015-11-01

    Full Text Available The chemical composition, antioxidant, cytotoxic and antiviral activities of the essential oil obtained by hydrodistillation from the aerial parts of Teucrium pseudochamaepitys (Lamiaceae collected from Zaghouan province of Tunisia are reported. The essential oil was analyzed by gas chromatography equipped with a flame ionization detector (GC-FID and gas chromatography coupled with mass spectrometry (GC/MS. Thirty-one compounds were identified representing 88.6% of the total essential oil. Hexadecanoic acid was found to be the most abundant component (26.1% followed by caryophyllene oxide (6.3%, myristicin (4.9% and α-cubebene (3.9%. The antioxidant capacity of the oil was measured on the basis of the scavenging activity to the stable 2,2-diphenyl-1-picrylhydrazyl (DPPH. The IC50 value of the oil was evaluated as 0.77 mg·mL−1. In addition, the essential oil was found to possess moderate cytotoxic effects on the HEp-2 cell line (50% cytotoxic concentration (CC50 = 653.6 µg·mL−1. The potential antiviral effect was tested against Coxsackievirus B (CV-B, a significant human and mouse pathogen that causes pediatric central nervous system disease, commonly with acute syndromes. The reduction of viral infectivity by the essential oil was measured using a cytopathic (CPE reduction assay.

  7. Brain activation for spontaneous and explicit false belief tasks overlaps: new fMRI evidence on belief processing and violation of expectation.

    Science.gov (United States)

    Bardi, Lara; Desmet, Charlotte; Nijhof, Annabel; Wiersema, Jan R; Brass, Marcel

    2017-03-01

    There is extensive discussion on whether spontaneous and explicit forms of ToM are based on the same cognitive/neural mechanisms or rather reflect qualitatively different processes. For the first time, we analyzed the BOLD signal for false belief processing by directly comparing spontaneous and explicit ToM task versions. In both versions, participants watched videos of a scene including an agent who acquires a true or false belief about the location of an object (belief formation phase). At the end of the movies (outcome phase), participants had to react to the presence of the object. During the belief formation phase, greater activity was found for false vs true belief trials in the right posterior parietal cortex. The ROI analysis of the right temporo-parietal junction (TPJ), confirmed this observation. Moreover, the anterior medial prefrontal cortex (aMPFC) was active during the outcome phase, being sensitive to violation of both the participant's and agent's expectations about the location of the object. Activity in the TPJ and aMPFC was not modulated by the spontaneous/explicit task. Overall, these data show that neural mechanisms for spontaneous and explicit ToM overlap. Interestingly, a dissociation between TPJ and aMPFC for belief tracking and outcome evaluation, respectively, was also found. © The Author (2016). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  8. Nuclear Forensics and Radiochemistry: Fission

    Energy Technology Data Exchange (ETDEWEB)

    Rundberg, Robert S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-11-07

    Radiochemistry has been used to study fission since it’ discovery. Radiochemical methods are used to determine cumulative mass yields. These measurements have led to the two-mode fission hypothesis to model the neutron energy dependence of fission product yields. Fission product yields can be used for the nuclear forensics of nuclear explosions. The mass yield curve depends on both the fuel and the neutron spectrum of a device. Recent studies have shown that the nuclear structure of the compound nucleus can affect the mass yield distribution.

  9. Micro plate fission chamber development

    International Nuclear Information System (INIS)

    Wang Mei; Wen Zhongwei; Lin Jufang; Jiang Li; Liu Rong; Wang Dalun

    2014-01-01

    To conduct the measurement of neutron flux and the fission rate distribution at several position in assemblies, the micro plate fission chamber was designed and fabricated. Since the requirement of smaller volume and less structure material was taken into consideration, it is convinient, commercial and practical to use fission chamber to measure neutron flux in specific condition. In this paper, the structure of fission chamber and process of fabrication were introduced and performance test result was presented. The detection efficiency is 91.7%. (authors)

  10. Predicting stroop effect from spontaneous neuronal activity: a study of regional homogeneity.

    Science.gov (United States)

    Liu, Congcong; Chen, Zhencai; Wang, Ting; Tang, Dandan; Hitchman, Glenn; Sun, Jiangzhou; Zhao, Xiaoyue; Wang, Lijun; Chen, Antao

    2015-01-01

    The Stroop effect is one of the most robust and well-studied phenomena in cognitive psychology and cognitive neuroscience. However, little is known about the relationship between intrinsic brain activity and the individual differences of this effect. In the present study, we explored this issue by examining whether resting-state functional magnetic resonance imaging (rs-fMRI) signals could predict individual differences in the Stroop effect of healthy individuals. A partial correlation analysis was calculated to examine the relationship between regional homogeneity (ReHo) and Stroop effect size, while controlling for age, sex, and framewise displacement (FD). The results showed positive correlations in the left inferior frontal gyrus (LIFG), the left insula, the ventral anterior cingulate cortex (vACC), and the medial frontal gyrus (MFG), and negative correlation in the left precentral gyrus (LPG). These results indicate the possible influences of the LIFG, the left insula, and the LPG on the efficiency of cognitive control, and demonstrate that the key nodes of default mode network (DMN) may be important in goal-directed behavior and/or mental effort during cognitive control tasks.

  11. Neural activations during visual sequence learning leave a trace in post-training spontaneous EEG.

    Directory of Open Access Journals (Sweden)

    Clara Moisello

    Full Text Available Recent EEG studies have shown that implicit learning involving specific cortical circuits results in an enduring local trace manifested as local changes in spectral power. Here we used a well characterized visual sequence learning task and high density-(hd-EEG recording to determine whether also declarative learning leaves a post-task, local change in the resting state oscillatory activity in the areas involved in the learning process. Thus, we recorded hd-EEG in normal subjects before, during and after the acquisition of the order of a fixed spatial target sequence (VSEQ and during the presentation of targets in random order (VRAN. We first determined the temporal evolution of spectral changes during VSEQ and compared it to VRAN. We found significant differences in the alpha and theta bands in three main scalp regions, a right occipito-parietal (ROP, an anterior-frontal (AFr, and a right frontal (RFr area. The changes in frontal theta power during VSEQ were positively correlated with the learning rate. Further, post-learning EEG recordings during resting state revealed a significant increase in alpha power in ROP relative to a pre-learning baseline. We conclude that declarative learning is associated with alpha and theta changes in frontal and posterior regions that occur during the task, and with an increase of alpha power in the occipito-parietal region after the task. These post-task changes may represent a trace of learning and a hallmark of use-dependent plasticity.

  12. Spontaneous pre-stimulus fluctuations in the activity of right fronto-parietal areas influence inhibitory control performance

    Directory of Open Access Journals (Sweden)

    Camille F. Chavan

    2013-06-01

    Full Text Available Inhibitory control refers to the ability to suppress planned or ongoing cognitive or motor processes. Electrophysiological indices of inhibitory control failure have been found to manifest even before the presentation of the stimuli triggering the inhibition, suggesting that pre-stimulus brain-states modulate inhibition performance. However, previous electrophysiological investigations on the state-dependency of inhibitory control were based on averaged event-related potentials, a method eliminating the variability in the ongoing brain activity not time-locked to the event of interest. These studies thus left unresolved whether spontaneous variations in the brain-state immediately preceding unpredictable inhibition-triggering stimuli also influence inhibitory control performance.To address this question, we applied single-trial EEG topographic analyses on the time interval immediately preceding NoGo stimuli in conditions where the responses to NoGo trials were correctly inhibited (correct rejection vs. committed (false alarms during an auditory spatial Go/NoGo task.We found a specific configuration of the EEG voltage field manifesting more frequently before correctly inhibited responses to NoGo stimuli than before false alarms. There was no evidence for an EEG topography occurring more frequently before false alarms than before correct rejections. The visualization of distributed electrical source estimations of the EEG topography preceding successful response inhibition suggested that it resulted from the activity of a right fronto-parietal brain network.Our results suggest that the fluctuations in the ongoing brain activity immediately preceding stimulus presentation contribute to the behavioral outcomes during an inhibitory control task. Our results further suggest that the state-dependency of sensory-cognitive processing might not only concern perceptual processes, but also high-order, top-down inhibitory control mechanisms.

  13. Decreased Spontaneous Electrical Activity and Acetylcholine at Myofascial Trigger Spots after Dry Needling Treatment: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Qing-Guang Liu

    2017-01-01

    Full Text Available Objective. The aims of this study are to investigate the changes in spontaneous electrical activities (SEAs and in acetylcholine (ACh, acetylcholine receptor (AChR, and acetylcholine esterase (AChE levels after dry needling at myofascial trigger spots in model rats. Materials and Methods. Forty-eight male Sprague-Dawley rats were divided into four groups. Thirty-six rats were assigned to three model groups, which underwent MTrSs modeling intervention. Twelve rats were assigned to the blank control (BC group. After model construction, the 36 model rats were randomly subdivided into three groups according to treatment: MTrSs model control (MC and two dry needling groups. One dry needling group received puncturing at MTrSs (DN-M, whereas the other underwent puncturing at non-MTrSs (DN-nM. Dry needling treatment will last for two weeks, once a week. SEAs and ACh, AChR, and AChE levels were measured after one-week rest of dry needling treatment. Results. The amplitudes and frequencies of endplate noise (EPN and endplate spike (EPS significantly decreased after dry needling treatment in the DN-M group. Moreover, ACh and AChR levels significantly decreased, whereas AChE significantly increased after dry needling treatment in the DN-M group. Conclusion. Dry needling at the exact MTrSs is more effective than dry needling at non-MTrSs.

  14. Self-monitoring of spontaneous physical activity and sedentary behavior to prevent weight regain in older adults.

    Science.gov (United States)

    Nicklas, Barbara J; Gaukstern, Jill E; Beavers, Kristen M; Newman, Jill C; Leng, Xiaoyan; Rejeski, W Jack

    2014-06-01

    The objective was to determine whether adding a self-regulatory intervention (SRI) focused on self-monitoring of spontaneous physical activity (SPA) and sedentary behavior to a standard weight loss intervention improved maintenance of lost weight. Older (65-79 years), obese (BMI = 30-40 kg/m(2) ) adults (n = 48) were randomized to a 5-month weight loss intervention involving a hypocaloric diet (DIET) and aerobic exercise (EX) with or without the SRI to promote SPA and decrease sedentary behavior (SRI + DIET + EX compared with DIET + EX). Following the weight loss phase, both groups transitioned to self-selected diet and exercise behavior during a 5-month follow-up. Throughout the 10-months, the SRI + DIET + EX group utilized real-time accelerometer feedback for self-monitoring. There was an overall group by time effect of the SRI (P weight and regained more weight than SRI + DIET + EX. The average weight regain during follow-up was 1.3 kg less in the SRI + DIET + EX group. Individuals in this group maintained approximately 10% lower weight than baseline compared with those in the DIET + EX group whom maintained approximately 5% lower weight than baseline. Addition of a SRI, designed to increase SPA and decrease sedentary behavior, to a standard weight loss intervention enhanced successful maintenance of lost weight. Copyright © 2014 The Obesity Society.

  15. Chain yields from 19.1 MeV neutron-induced fission of 235U

    International Nuclear Information System (INIS)

    Bao Jie; Yang Yi; Liu Yonghui; Feng Jing; Li Ze; Cui Anzhi; Sun Hongqing; Zhang Shengdong; Guo Jingru

    2001-01-01

    Chain yields for 35 mass chains were determined for the fission of 235 U induced by 19.1 MeV neutrons for the first time. Absolute fission rate was monitored with a double fission chamber; fission product activities were measured by HPGe γ-ray spectrometry. Threshold detector method was used to measured the neutron spectrum in order to estimate the fission events induced by break-up neutrons and scattering neutrons from the environment. A mass distribution curve has been obtained

  16. Brief description of out-of-pile test facilities for study in corrosion and fission product behaviour in flowing sodium

    International Nuclear Information System (INIS)

    Iizawa, K.; Sekiguchi, N.; Atsumo, H.

    1976-01-01

    The experimental methods to perform tests for study in corrosion and fission products behaviour in flowing sodium are outlined. Flow diagrams for the activated materials and fission products behaviour test loop are given

  17. Comparison of {sup 235}U fission cross sections in JENDL-3.3 and ENDF/B-VI

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, Toshihiko [Kyushu Univ., Fukuoka (Japan); Carlson, Allan D. [National Institute of Standards and Technology (United States); Matsunobu, Hiroyuki [Data Engineering, Inc., Fujisawa, Kanagawa (Japan); Nakagawa, Tsuneo; Shibata, Keiichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Talou, Patrick; Young, Philip G.; Chadwick, Mark B. [Los Alamos National Laboratory, Los Alamos, NM (United States)

    2002-01-01

    Comparisons of evaluated fission cross sections for {sup 235}U in JENDL-3.3 and ENDF/B-VI are carried out. The comparisons are made for both the differential and integral data. The fission cross sections as well as the fission ratios are compared with the experimental data in detail. Spectrum averaged cross sections are calculated and compared with the measurements. The employed spectra are the {sup 235}U prompt fission neutron spectrum, the {sup 252}Cf spontaneous fission neutron spectrum, and the neutron spectrum produced by a {sup 9}Be(d, xn) reaction. For {sup 235}U prompt fission neutron spectrum, the ENDF/B-VI evaluation reproduces experimental averaged cross sections. For {sup 252}Cf and {sup 9}Be(d, xn) neutron spectra, the JENDL-3.3 evaluation gives better results than ENDF/B-VI. (author)

  18. Comparison of 235U fission cross sections in JENDL-3.3 and ENDF/B-VI

    International Nuclear Information System (INIS)

    Kawano, Toshihiko; Carlson, Allan D.; Matsunobu, Hiroyuki; Nakagawa, Tsuneo; Shibata, Keiichi

    2002-01-01

    Comparisons of evaluated fission cross sections for 235 U in JENDL-3.3 and ENDF/B-VI are carried out. The comparisons are made for both the differential and integral data. The fission cross sections as well as the fission ratios are compared with the experimental data in detail. Spectrum averaged cross sections are calculated and compared with the measurements. The employed spectra are the 235 U prompt fission neutron spectrum, the 252 Cf spontaneous fission neutron spectrum, and the neutron spectrum produced by a 9 Be(d, xn) reaction. For 235 U prompt fission neutron spectrum, the ENDF/B-VI evaluation reproduces experimental averaged cross sections. For 252 Cf and 9 Be(d, xn) neutron spectra, the JENDL-3.3 evaluation gives better results than ENDF/B-VI. (author)

  19. Tip model of cold fission

    International Nuclear Information System (INIS)

    Goennenwein, F.; Boersig, B.

    1991-01-01

    Cold fission is defined to be the limiting case of nuclear fission where virtually all of the available energy is converted into the total kinetic energy of the fragments. The fragments have, therefore, to be born in or at least close to their respective ground states. Starting from the viewpoint that cold fission corresponds to most compact scission configurations, energy constraints have been exploited to calculate minimum tip distances between the two nascent fragments in binary fission. Crucial input parameters to this tip model of cold fission are the ground-state deformations of fragment nuclei. It is shown that the minimum tip distances being compatible with energy conservation vary strongly with both the mass and charge fragmentation of the fission prone nucleus. The tip distances refer to nuclei with equivalent sharp surfaces. In keeping with the size of the surface width of leptodermous nuclei, only configurations where the tip distances are smaller than a few fm may be considered as valid scission configurations. From a comparison with experimental data on cold fission this critical tip distance appears to be 3.0 fm for the model parameters chosen. Whenever the model calculation yields tip distances being smaller than the critical value, a necessary condition for attaining cold fission is considered to be fulfilled. It is shown that this criterion allows to understand in fair agreement with experiment which mass fragmentations are susceptible to lead to cold fission and which fragment-charge divisions are the most favored in each isobaric mass chain. Being based merely on energy arguments, the model cannot aim at predicting fragment yields in cold fission. However, the tip model proposed appears well suited to delineate the phase space where cold fission phenomena may come into sight. (orig.)

  20. Effect of a non lethal whole-body gamma irradiation on the spontaneous and evoked electroencephalographic activities of the adult rabbit

    International Nuclear Information System (INIS)

    Court, L.

    1969-01-01

    The whole of the experimental methods described (animal preparation, achievement of a precise physiological technique, dosimetry, biological information processing) allowed us to follow the changes for 15 days in the spontaneous and evoked electroencephalogram activities of rabbits submitted to a non-lethal 400 rads whole-body gamma-irradiation. Behavioural troubles, changes in the arousal state and the spontaneous electrical activity of the neo-cortex and hippocampus were noticed constantly together with an enhanced cortical excitability, and the appearance of elements of the paroxystic series sometimes in contrast with a general decrease in amplitude. After a visual stimulus the general morphology of evoked activities at the level of the primary visual areas and hippocampus was unchanged, but enhanced latencies and delays, less systematic modifications in amplitudes seemed to show out a direct effect of radiations on the nervous system and sensorial activities; these troubles seemed to occur independently from the basic electrical activity. As a whole, the changes observed were usually transitory and varied with each individual. Finally an assumption is made to explain the mechanism of arousal troubles and the general evolution of spontaneous electrical activity in the brain. (author) [fr

  1. Post-scission fission theory: Neutron emission in fission

    International Nuclear Information System (INIS)

    Madland, D.G.

    1997-01-01

    A survey of theoretical representations of two of the observables in neutron emission in fission is given, namely, the prompt fission neutron spectrum N (E) and the average prompt neutron multiplicity bar ν p . Early representations of the two observables are presented and their deficiencies are discussed. This is followed by summaries and examples of recent theoretical models for the calculation of these quantities. Emphasis is placed upon the predictability and accuracy of the recent models. In particular, the dependencies of N (E) and bar ν p upon the fissioning nucleus and its excitation energy are treated. Recent work in the calculation of the prompt fission neutron spectrum matrix N (E, E n ), where E n is the energy of the neutron inducing fission, is then discussed. Concluding remarks address the current status of our ability to calculate these observables with confidence, the direction of future theoretical efforts, and limitations to current (and future) approaches

  2. Associations of lifetime active and passive smoking with spontaneous abortion, stillbirth and tubal ectopic pregnancy: a cross-sectional analysis of historical data from the Women's Health Initiative.

    Science.gov (United States)

    Hyland, Andrew; Piazza, Kenneth M; Hovey, Kathleen M; Ockene, Judith K; Andrews, Christopher A; Rivard, Cheryl; Wactawski-Wende, Jean

    2015-07-01

    To examine the associations between tobacco exposure and adverse pregnancy outcomes using quantitative measures of lifetime active smoking and secondhand smoke (SHS) exposure. Historical reproductive data on 80 762 women who participated in the Women's Health Initiative Observational Study were examined with a cross-sectional analysis. We assessed self-reported lifetime active and passive tobacco smoke exposure, self-reported spontaneous abortions, stillbirths and ectopic pregnancies. When compared with never-smoking women, participants who were ever active smokers during their reproductive years had ORs (OR) of 1.16 (95% CI 1.08 to 1.26) for 1 or more spontaneous abortions, 1.44 (95% CI 1.20 to 1.73) for 1 or more stillbirths, and 1.43 (95% CI 1.10 to 1.86) for 1 or more ectopic pregnancies. Never-smoking women participants with the highest levels of lifetime SHS exposure, including childhood >10 years, adult home >20 years and adult work exposure >10 years, when compared with never-smoking women with no SHS exposure had adjusted ORs of 1.17 (95% CI 1.05 to 1.30) for spontaneous abortion, 1.55 (95% CI 1.21 to 1.97) for stillbirth, and 1.61 (95% CI 1.16 to 2.24) for ectopic pregnancy. Women who were ever-smokers during their reproductive years had significantly greater estimates of risk for spontaneous abortion, stillbirth and tubal ectopic pregnancy. Never-smoking women with the highest levels of lifetime exposure to SHS had significantly increased estimates of risk for spontaneous abortion, stillbirth and tubal ectopic pregnancy. 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.

  3. Intervening on spontaneous physical activity to prevent weight regain in older adults: design of a randomized, clinical trial.

    Science.gov (United States)

    Nicklas, Barbara J; Gaukstern, Jill E; Legault, Claudine; Leng, Iris; Rejeski, W Jack

    2012-03-01

    There is a need to identify evidenced-based obesity treatments that are effective in maintaining lost weight. Weight loss results in reductions in energy expenditure, including spontaneous physical activity (SPA) which is defined as energy expenditure resulting primarily from unstructured mobility-related activities that occur during daily life. To date, there is little research, especially randomized, controlled trials, testing strategies that can be adopted and sustained to prevent declines in SPA that occur with weight loss. Self-monitoring is a successful behavioral strategy to facilitate behavior change, so a provocative question is whether monitoring SPA-related energy expenditure would override these reductions in SPA, and slow weight regain. This study is a randomized trial in older, obese men and women designed to test the hypothesis that adding a self-regulatory intervention (SRI), focused around self-monitoring of SPA, to a weight loss intervention will result in less weight and fat mass regain following weight loss than a comparable intervention that lacks this self-regulatory behavioral strategy. Participants (n=72) are randomized to a 5-month weight loss intervention with or without the addition of a behavioral component that includes an innovative approach to promoting increased SPA. Both groups then transition to self-selected diet and exercise behavior for a 5-month follow-up. Throughout the 10-month period, the SRI group is provided with an intervention designed to promote a SPA level that is equal to or greater than each individual's baseline SPA level, allowing us to isolate the effects of the SPA self-regulatory intervention component on weight and fat mass regain. Copyright © 2011 Elsevier Inc. All rights reserved.

  4. Structures and properties of (U,Pu)O2 containing non-active fission products. A simulation of irradiated nuclear fuel

    International Nuclear Information System (INIS)

    Schmitz, F.

    1969-01-01

    We have made oxides with the same uranium and plutonium content, the same stoichiometry and the same fission product content as an oxide fuel (U 0,8 PuO 2 )O 1,96 after 2 per cent burn up. We have calculated the stoichiometry changes due to irradiation and checked the calculation by X rays parameters measurements. We have calculated and measured the contraction of the oxide lattice due to fission products in solid solution. Microprobe analysis of precipitates have been made and have lead to the identification of non metallic barium containing compounds and have shown the particular behaviour of molybdenum. Some physical properties have been measured especially the electrical resistivity, the thermal diffusivity and the vapour pressure of zirconium in solid solution. (author) [fr

  5. Fission hindrance and nuclear viscosity

    Indian Academy of Sciences (India)

    viscosity in slowing down the diffusion rate in comparison to the decay rate without vis- cosity predicted by Bohr and ... revived Kramers' dynamical approach to understand nuclear fission at finite temperature and angular momentum. ... tor and (2) a compact seven-element array of BaF2 detectors. The fission fragments were.

  6. Discoveries of isotopes by fission

    Indian Academy of Sciences (India)

    also contributed to the discovery of new isotopes. More recently, most of the very neutron- rich isotopes have been discovered by projectile fission. After a brief summary of the discovery of fission process itself, these production mechanisms will be discussed. The paper concludes with an outlook on future discoveries of ...

  7. Fission throughout the periodic table

    International Nuclear Information System (INIS)

    Moretto, L.G.; Wozniak, G.J.

    1989-04-01

    The dualistic view of fission and evaporation as two distinct compound nucleus processes is substituted with a unified view in which fission, complex fragment emission, and light particle evaporation are seen as different aspects of a single process. 47 refs., 22 figs

  8. Properties of true quaternary fission of nuclei with allowance for its multistep and sequential character

    Energy Technology Data Exchange (ETDEWEB)

    Kadmensky, S. G., E-mail: kadmensky@phys.vsu.ru; Titova, L. V.; Bulychev, A. O. [Voronezh State University (Russian Federation)

    2015-07-15

    An analysis of basicmechanisms of binary and ternary fission of nuclei led to the conclusion that true ternary and quaternary fission of nuclei has a sequential two-step (three-step) character, where, at the first step, a fissile nucleus emits a third light particle (third and fourth light particles) under shakeup effects associated with a nonadiabatic character of its collective deformation motion, whereupon the residual nucleus undergoes fission to two fission fragments. Owing to this, the formulas derived earlier for the widths with respect to sequential two- and three-step decays of nuclei in constructing the theory of two-step twoproton decays and multistep decays in chains of genetically related nuclei could be used to describe the relative yields and angular and energy distributions of third and fourth light particles emitted in (α, α), (t, t), and (α, t) pairs upon the true quaternary spontaneous fission of {sup 252}Cf and thermal-neutron-induced fission of {sup 235}U and {sup 233}U target nuclei. Mechanisms that explain a sharp decrease in the yield of particles appearing second in time and entering into the composition of light-particle pairs that originate from true quaternary fission of nuclei in relation to the yields of analogous particles in true ternary fission of nuclei are proposed.

  9. Industrial use of fission products

    International Nuclear Information System (INIS)

    Silverman, J.

    1989-01-01

    Perhaps the most disappointing and surprising development in the fifty year history of nuclear fission is the small role fission products play in modern technology. As a large and potentially inexpensive source of ionizing radiation, fission products were expected to offer major practical benefits. The attractive opportunities stimulated imaginative efforts to realize their fulfillment, but their direct impact has been minor. Fission products have not fared well, not only in somewhat indirect competition with nonradioactive alternatives, but also in direct competition with other radiation sources, especially electron accelerators and 60 Co. There is one major triumph for fission product technology: the application of 99 Mo and its daughter 99m Tc as an almost universal tracer system in nuclear medicine

  10. Mechanisms of fission neutron emission

    International Nuclear Information System (INIS)

    Maerten, H.

    1991-01-01

    The time evolution in fission is the starting point for discussing not only the main mechanism of fission neutron emission, the evaporation from fully accelerated fragments, but also possible secondary ones connected with dynamical features of nuclear fission. ''Asymptotic'' conditions as relevant for describing the particle release from highly excited, rapidly moving fragments are defined. Corresponding statistical model approaches to fission neutron emission, based on the adequate consideration of the intricate fragment occurrence probability, reproduce most of the experimental data. The remarkable influence of fission modes on neutron observables is analyzed in the framework of a macroscopic-microscopic scission point model consistent with energy conservation. Finally, chances and deficiencies for solving the mechanism puzzle are summarized. (author). 87 refs, 21 figs

  11. Ternary fission and cluster radioactivities

    CERN Document Server

    Poenaru, D N; Greiner, W; Gherghescu, R A; Hamilton, J H; Ramayya, A V

    2002-01-01

    Ternary fission yield for different kinds of light particle accompanied fission processes is compared to the Q-values for the corresponding cold phenomena, showing a striking correlation. The experimental evidence for the existence of a quasimolecular state in sup 1 sup 0 Be accompanied fission of sup 2 sup 5 sup 2 Cf may be explained using a three-center phenomenological model which generates a third minimum in the deformation energy at a separation distance very close to the touching point. This model is a natural extension of the unified approach to three groups of binary decay modes (cold fission, cluster radioactivities and alpha decay), illustrated by sup 2 sup 3 sup 4 U decay modes, and the alpha valley on the potential energy surfaces of sup 1 sup 0 sup 6 Te. New measurements of cluster decay modes, confirming earlier predictions within analytical superasymmetric fission model, are included in a comprehensive half-life systematics. (authors)

  12. High precision measurements on fission-fragment de-excitation

    Science.gov (United States)

    Oberstedt, Stephan; Gatera, Angélique; Geerts, Wouter; Göök, Alf; Hambsch, Franz-Josef; Vidali, Marzio; Oberstedt, Andreas

    2017-11-01

    In recent years nuclear fission has gained renewed interest both from the nuclear energy community and in basic science. The first, represented by the OECD Nuclear Energy Agency, expressed the need for more accurate fission cross-section and fragment yield data for safety assessments of Generation IV reactor systems. In basic science modelling made much progress in describing the de-excitation mechanism of neutron-rich isotopes, e.g. produced in nuclear fission. Benchmarking the different models require a precise experimental data on prompt fission neutron and γ-ray emission, e.g. multiplicity, average energy per particle and total dissipated energy per fission, preferably as function of fission-fragment mass and total kinetic energy. A collaboration of scientists from JRC Geel (formerly known as JRC IRMM) and other institutes took the lead in establishing a dedicated measurement programme on prompt fission neutron and γ-ray characteristics, which has triggered even more measurement activities around the world. This contribution presents new advanced instrumentation and methodology we use to generate high-precision spectral data and will give a flavour of future data needs and opportunities.

  13. Proceedings of the specialists' meeting on physics and engineering of fission and spallation, 1989

    International Nuclear Information System (INIS)

    Nakagome, Yoshihiro

    1990-07-01

    The third meeting was held on August 1, and the fourth meeting was held on December 12, 1989. The reports of the international conferences on 50 years research on nuclear fission in Germany and USA, and the reports on the nuclear data of fission-produced nuclei for evaluating reactor decay heat, the atomic mass formula considering proton-neutron interaction and unstable nuclei, research on short life fission fragments by on-line isotope separation process, the reactor physics on waste annihilation disposal and fuel breeding with an accelerator, the double differential cross section of back neutrons in nuclear spallation reaction, measurement of fission cross section and fission neutron spectra with fast neutrons, U-235 fission spectra by unfolding activation foil data and production mechanisms of intermediate mass fragments from hot nuclei-emission of complex and fission fragments for 84 Kr+ 27 Al at 10.6 MeV/u were made. (K.I.)

  14. Unaltered Network Activity and Interneuronal Firing During Spontaneous Cortical Dynamics In Vivo in a Mouse Model of Severe Myoclonic Epilepsy of Infancy.

    Science.gov (United States)

    De Stasi, Angela Michela; Farisello, Pasqualina; Marcon, Iacopo; Cavallari, Stefano; Forli, Angelo; Vecchia, Dania; Losi, Gabriele; Mantegazza, Massimo; Panzeri, Stefano; Carmignoto, Giorgio; Bacci, Alberto; Fellin, Tommaso

    2016-04-01

    Severe myoclonic epilepsy of infancy (SMEI) is associated with loss of function of the SCN1A gene encoding the NaV1.1 sodium channel isoform. Previous studies in Scn1a(-/+) mice during the pre-epileptic period reported selective reduction in interneuron excitability and proposed this as the main pathological mechanism underlying SMEI. Yet, the functional consequences of this interneuronal dysfunction at the circuit level in vivo are unknown. Here, we investigated whether Scn1a(-/+) mice showed alterations in cortical network function. We found that various forms of spontaneous network activity were similar in Scn1a(-/+) during the pre-epileptic period compared with wild-type (WT) in vivo. Importantly, in brain slices from Scn1a(-/+) mice, the excitability of parvalbumin (PV) and somatostatin (SST) interneurons was reduced, epileptiform activity propagated more rapidly, and complex synaptic changes were observed. However, in vivo, optogenetic reduction of firing in PV or SST cells in WT mice modified ongoing network activities, and juxtasomal recordings from identified PV and SST interneurons showed unaffected interneuronal firing during spontaneous cortical dynamics in Scn1a(-/+) compared with WT. These results demonstrate that interneuronal hypoexcitability is not observed in Scn1a(-/+) mice during spontaneous activities in vivo and suggest that additional mechanisms may contribute to homeostatic rearrangements and the pathogenesis of SMEI. © The Author 2016. Published by Oxford University Press.

  15. Effect of calorie restriction on spontaneous physical activity and body mass in mice divergently selected for basal metabolic rate (BMR).

    Science.gov (United States)

    Brzęk, Paweł; Gębczyński, Andrzej K; Książek, Aneta; Konarzewski, Marek

    2016-07-01

    Spontaneous physical activity (SPA) represents an important component of daily energy expenditures in animals and humans. Intra-specific variation in SPA may be related to the susceptibility to metabolic disease or obesity. In particular, reduced SPA under conditions of limited food availability may conserve energy and prevent loss of body and fat mass ('thrifty genotype hypothesis'). However, both SPA and its changes during food restriction show wide inter-individual variations. We studied the effect of 30% caloric restriction (CR) on SPA in laboratory mice divergently selected for high (H-BMR) and low (L-BMR) basal metabolic rate. Selection increased SPA in the H-BMR line but did not change it in the L-BMR mice. This effect reflected changes in SPA intensity but not SPA duration. CR increased SPA intensity more strongly in the L-BMR line than in the H-BMR line and significantly modified the temporal variation of SPA. However, the initial between-line differences in SPA were not affected by CR. Loss of body mass during CR did not differ between both lines. Our results show that the H-BMR mice can maintain their genetically determined high SPA under conditions of reduced food intake without sacrificing their body mass. We hypothesize that this pattern may reflect the higher flexibility in the energy budget in the H-BMR line, as we showed previously that mice from this line reduced their BMR during CR. These energy savings may allow for the maintenance of elevated SPA in spite of reduced food intake. We conclude that the effect of CR on SPA is in large part determined by the initial level of BMR, whose variation may account for the lack of universal pattern of behavioural responses to CR. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Association of exercise training and angiotensin-converting enzyme 2 activator improves baroreflex sensitivity of spontaneously hypertensive rats.

    Science.gov (United States)

    Lopes, P R; Moreira, M C S; Marques, S M; Pinto, I S J; Macedo, L M; Silva, C C; Freiria-Oliveira, A H; Rebelo, A C S; Reis, A A S; Rosa, D A; Ferreira-Neto, M L; Castro, C H; Pedrino, G R

    2016-08-01

    The present study sought to determine cardiovascular effects of aerobic training associated with diminazene aceturate (DIZE), an activator of the angiotensin converting enzyme 2, in spontaneously hypertensive rats (SHRs). Male SHRs (280-350 g) were either subjected to exercise training or not (sedentary group). The trained group was subjected to 8 weeks of aerobic training on a treadmill (five times a week, lasting 60 min at an intensity of 50-60% of maximum aerobic speed). In the last 15 days of the experimental protocol, these groups were redistributed into four groups: i) sedentary SHRs with daily treatment of 1 mg/kg DIZE (S+D1); ii) trained SHRs with daily treatment of 1 mg/kg DIZE (T+D1); iii) sedentary SHRs with daily treatment of vehicle (S+V); and iv) trained SHRs with daily treatment of vehicle (T+V). After treatment, SHRs were anesthetized and subjected to artery and femoral vein cannulation prior to the implantation of ECG electrode. After 24 h, mean arterial pressure (MAP) and heart rate (HR) were recorded; the baroreflex sensitivity and the effect of double autonomic blockade (DAB) were evaluated in non-anesthetized SHRs. DIZE treatment improved baroreflex sensitivity in the T+D1 group as compared with the T+V and S+D1 groups. The intrinsic heart rate (IHR) and MAP were reduced in T+D1 group as compared with T+V and S+D1 groups. Hence, we conclude that the association of exercise training with DIZE treatment improved baroreflex function and cardiovascular regulation.

  17. Functional Architecture of Noise Correlations in Human Early Visual Cortex and its Relationship with Coherent Spontaneous Activity

    Directory of Open Access Journals (Sweden)

    Jungwon Ryu

    2012-10-01

    Full Text Available Responses of single sensory neurons to stimuli are ‘noisy’, varying substantially across repeated trials of identical stimulation. Intriguingly, these individual ‘noise responses’ (NR—deviations from their means—are not isolated; rather they are highly correlated, referred to as ‘noise correlation’ (NC. From a computational viewpoint, the presence and nature of NC exert great impacts on the information processing capacity of neurons as they encode sensory events as a population, decode those encoded neural responses, and contribute to perceptual choices for action. Regarding the origin of NR, on the other hand, there has been growing evidence pointing to its tight linkage with ‘spontaneous responses’ (SR—fluctuations of neural activity in the absence of external input or tasks. To investigate the functional structure of NC and its relationship with ‘correlations in SR’ (SC, we defined population receptive fields (pRFs of unit volumes of gray matter (UV in human early visual cortex and computed NRs and SRs using fMRI. NC increased with an increasing degree of similarity in pRF tuning properties such as orientation, spatial frequency, and visuotopic position, particularly between UV pairs close in cortical distance. This ‘like-to-like’ structure of NC remained unaltered across scan runs with different stimuli, even among between-area UV pairs. SC was higher than NC, and its functional and temporal structures were quite similar to those of NC. Furthermore, the partial correlation analysis revealed that NC between a given pair of UVs was best predicted by their SC than by any other factors examined in the current study.

  18. Fission fragment angular distribution in heavy ion induced fission

    Directory of Open Access Journals (Sweden)

    S. Soheyli

    2006-06-01

    Full Text Available   We have calculated the fission fragment angular anisotropy for 16O + 232Th,12C + 236U , 11B + 237 Np , 14 N + 232 Th , 11B + 235U , 12C + 232Th systems with the saddle point statistical model and compared the fission fragment angular anisotropy for these systems. This comparison was done with two methods a without neutron correction and b with neutron correction. Also we studied normal and anomalous behavior of the fission fragment angular anisotropy. Finally, we have predicted the average emitted neutron from compound nuclei considering the best fit for each system.

  19. Fission fragment angular distribution in heavy ion induced fission

    OpenAIRE

    S. Soheyli; I. Ziaeian

    2006-01-01

      We have calculated the fission fragment angular anisotropy for 16O + 232Th,12C + 236U , 11B + 237 Np , 14 N + 232 Th , 11B + 235U , 12C + 232Th systems with the saddle point statistical model and compared the fission fragment angular anisotropy for these systems. This comparison was done with two methods a) without neutron correction and b) with neutron correction. Also we studied normal and anomalous behavior of the fission fragment angular anisotropy. Finally, we have predicted the averag...

  20. Pectoral fin beat frequency predicts oxygen consumption during spontaneous activity in a labriform swimming fish (Embiotoca lateralis)

    DEFF Research Database (Denmark)

    Tudorache, Christian; Jordan, Anders D.; Svendsen, Jon Christian

    2009-01-01

    The objective of this study was to identify kinematic variables correlated with oxygen consumption during spontaneous labriform swimming. Kinematic variables (swimming speed, change of speed, turning angle, turning rate, turning radius and pectoral fin beat frequency) and oxygen consumption (MO2......) of spontaneous swimming in Embiotoca lateralis were measured in a circular arena using video tracking and respirometry, respectively. The main variable influencing MO2 was pectoral fin beat frequency (r (2) = 0.71). No significant relationship was found between swimming speed and pectoral fin beat frequency...

  1. Dynamical excitation in fission

    International Nuclear Information System (INIS)

    Ledergerber, T.; Paltiel, Z.; Fraenkel, Z.; Pauli, H.C.

    1976-01-01

    The excitation mechanism of the fission process is studied in terms of a model of particles moving in a deformed time-dependent potential. A residual interaction of the pairing type is incoporated by means of the BCS approximation. Only 2-quasi-particle excitations up to some cutoff energy are included. The separation of the total excitation energy into intrinsic and translational parts is made at the scission point. The present calculations for 240 Pu show that, in the framework of this model, most of the available energy at scission is transformed into intrinsic excitation energy. However the convergence of the calculated value for the cutoff energy is unsatisfactory and hence a description in terms of a better model space is needed. The fact that very many channels are involved suggests that a statistical treatment may be useful. (author)

  2. Spontaneous mechanical and electrical activities of human calf musculature at rest assessed by repetitive single-shot diffusion-weighted MRI and simultaneous surface electromyography.

    Science.gov (United States)

    Schwartz, Martin; Steidle, Günter; Martirosian, Petros; Ramos-Murguialday, Ander; Preißl, Hubert; Stemmer, Alto; Yang, Bin; Schick, Fritz

    2018-05-01

    Assessment of temporal and spatial relations between spontaneous mechanical activities in musculature (SMAM) at rest as revealed by diffusion-weighted imaging (DWI) and electrical muscular activities in surface EMG (sEMG). Potential influences of static and radiofrequency magnetic fields on muscular activity on sEMG measurements at rest were examined systematically. Series of diffusion-weighted stimulated echo planar imaging were recorded with concurrent sEMG measurements. Electrical activities in sEMG were analyzed by non-parametric Friedman and two-sample Kolmogorov-Smirnov test. Direct correlation of both modalities was investigated by temporal mapping of electrical activity in sEMG to DWI repetition interval. Electrical activities in sEMG and number of visible SMAMs in DWI showed a strong correlation (ρ = 0.9718). High accordance between sEMG activities and visible SMAMs in DWI in a near-surface region around sEMG electrodes was achieved. Characteristics of sEMG activities were almost similar under varying magnetic field conditions. Visible SMAMs in DWI have shown a close and direct relation to concurrent signals recorded by sEMG. MR-related magnetic fields had no significant effects on findings in sEMG. Hence, appearance of SMAMs in DWI should not be considered as imaging artifact or as effects originating from the special conditions of MR examinations. Spatial and temporal distributions of SMAMs indicate characteristics of spontaneous (microscopic) mechanical muscular action at rest. Therefore, DWI techniques should be considered as non-invasive tools for studying physiology and pathophysiology of spontaneous activities in resting muscle. Magn Reson Med 79:2784-2794, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  3. Role of hindbrain melanocortin-4 receptor activity in controlling cardiovascular and metabolic functions in spontaneously hypertensive rats.

    Science.gov (United States)

    do Carmo, Jussara M; da Silva, Alexandre A; Hall, John E

    2015-06-01

    Although we previously demonstrated that activation of central nervous system (CNS) melanocortin3/4 receptors (MC3/4R) play a key role in blood pressure (BP) regulation, especially in spontaneously hypertensive rats (SHRs), the importance of hindbrain MC4R is still unclear. In the present study, we examined the cardiovascular and metabolic effects of chronic inhibition of MC3/4R in the hindbrain of SHRs and normotensive Wistar-Kyoto (WKY) rats. Male WKY rats (n = 6) and SHRs (n = 7) were implanted with telemetry probes to measure BP and heart rate (HR) 24 h/day, and an intracerebroventricular cannula was placed into the fourth ventricle. After 10 days of recovery and 5 days of control measurements, the MC3/4R antagonist (SHU-9119) was infused into the fourth ventricle (1 nmol/h) to antagonize hindbrain MC4R for 10 days, followed by a 5-day recovery period. Chronic hindbrain MC3/4R antagonism significantly increased food intake and body weight in WKY rats (17 ± 1 to 35 ± 2 g/day and 280 ± 8 to 353 ± 8 g) and SHRs (19 ± 2 to 35 ± 2 g/day and 323 ± 7 to 371 ± 11 g), and markedly increased fasting insulin and leptin levels while causing no changes in blood glucose levels (99 ± 4 to 87 ± 4 and 89 ± 5 to 89 ± 4 mg/dl, respectively, for WKY rats and SHRs). Chronic SHU-9119 infusion reduced mean arterial pressure and HR similarly in WKY rats (-8 ± 1 mmHg and -47 ± 3 b.p.m.) and SHRs (-11 ± 3 mmHg and -44 ± 3 b.p.m.). These results suggest that although hindbrain MC4R activity contributes to appetite and HR regulation, it does not play a major role in mediating the elevated BP in SHRs.

  4. Age-related weakening of baroreflex-mediated sympathetic activity in spontaneously hypertensive rats in response to blood pressure reduction.

    Science.gov (United States)

    Prados, P; Santa, T; Fukushima, T; Homma, H; Kasai, C; Martin, M A; del Castillo, B; Imai, K

    1998-09-01

    Nicardipine, a dihydropyridine type calcium channel blocker, was infused into 4-, 6-, and 23-wk-old spontaneously hypertensive (SH) and age-matched normotensive Wistar-Kyoto (WKY) rats (under sodium thiobutabarbital anesthesia and ventilation, n = 4) through the left femoral vein, resulting in the reduction of blood pressure. In each rat, mean arterial blood pressure, heart rate, and the concentration of plasma catecholamines (CAs), norepinephrine (NE), and epinephrine (E) were concomitantly determined, and the correlations between these three variables were studied. During the infusion of nicardipine, the plasma concentration of CAs was measured with an automatic detection system in blood samples collected from the right femoral artery of each rat. The reduction in blood pressure induced by nicardipine brought about an increase in plasma CA levels. The blood pressure correlated well with the logarithm of plasma NE or E concentration according to the formula Y= -alpha log (X) + m (Y, blood pressure; X, concentration of plasma NE or E; a, slope; and m, intercept). The slopes (as) of 6-wk-old and 23-wk-old SH rats were significantly greater than those of aged-matched WKY rats, meaning that the increment in plasma CAs in response to a decrease in blood pressure was smaller in SH than in WKY rats of similar ages. However, no significant differences were found between the as of 4-wk-old SH and WKY rats. We conclude that the increment in the baroreflex-mediated sympathetic activity in response to a drop in blood pressure induced by nicardipine is similar or greater in prehypertensive SH than in normotensive WKY 4-wk-old rats, while the increment becomes smaller in SH rats with the onset of hypertension (6-wk-old rats), and is much less in fully hypertensive adult (23-wk-old) SH rats than in age-matched WKY rats. On the basis of these findings and previous data obtained by neurography, we conclude that plasma CAs can be used to evaluate baroreflex-mediated sympathetic

  5. Primary angle-closure glaucomas disturb regional spontaneous brain activity in the visual pathway: an fMRI study

    Directory of Open Access Journals (Sweden)

    Chen W

    2017-05-01

    Full Text Available Wei Chen, Li Zhang, Yong-gen Xu, Kai Zhu, Man Luo Department of Ophthalmology, Shaoxing People’s Hospital, Shaoxing, Zhejiang, People’s Republic of China Objective: To explore the underlying regional brain activity deficits in the visual cortex in patients with primary angle-closure glaucoma (PACG relative to normal controls (NCs using regional homogeneity (ReHo method, and its relationship with behavioral performances. Patients: Twenty PACG patients (10 females, 10 males; mean age ± standard deviation [SD]: 54.42±9.46 years and 20 age-, and sex status-matched NCs (10 females, 10 males; mean age ± SD: 53.75±9.16 years were included in this study. Measurements and results: Compared with NCs, patients with PACG showed significant atrophic peripapillary retinal nerve fiber layer (pRNFL and neuroretinal rim area, increased optic disk cup-to-disc ratio (CDR and optic disk volume (P<0.05, higher ReHo value in the left fusiform gyrus, left cerebellum anterior lobe, right frontal-temporal space, and right insula, and lower ReHo value in the bilateral middle occipital gyrus, left claustrum, and right paracentral lobule lobe. The receiver operating characteristic analysis revealed these different areas with high value of area under curve, and high degree of sensitivity and specificity. The mean beta values of these different areas were extracted. In PACG, the duration of disease showed a negative correlation with the mean beta value of left cerebellum anterior lobe (r=-0.453, P=0.045 and a positive correlation with right middle occipital gyrus (r=0.586, P=0.007; left middle occipital gyrus showed positive correlations with duration of disease (r=0.562, P=0.01 and left pRNFL (r=0.49, P=0.028; left claustrum had a positive correlation with left CDR (r=0.515, P=0.02; and right paracentral lobule lobe demonstrated a positive correlation with left pRNFL (r=0.623, P=0.003. Conclusion: PACG is involved in abnormal spontaneous brain activity in multiple

  6. Conditional firing probabilities in cultured neuronal networks: a stable underlying structure in widely varying spontaneous activity patterns

    NARCIS (Netherlands)

    le Feber, Jakob; Rutten, Wim; Stegenga, J.; Wolters, P.S.; Ramakers, G.J.A.; van Pelt, J.

    2007-01-01

    To properly observe induced connectivity changes after training sessions, one needs a network model that describes individual relationships in sufficient detail to enable observation of induced changes and yet reveals some kind of stability in these relationships. We analyzed spontaneous firing

  7. The spectroscopy of fission fragments

    International Nuclear Information System (INIS)

    Phillips, W.R.

    1998-01-01

    High-resolution measurements on γ rays from fission fragments have provided a rich source of information, unobtainable at the moment in any other way, on the spectroscopy of neutron-rich nuclei. In recent years important data have been obtained on the yrast- and near yrast-structure of neutron-rich fission fragments. We discuss the scope of measurements which can be made on prompt gamma rays from secondary fission fragments, the techniques used in the experiments and some results recently obtained. (author)

  8. The spectroscopy of fission fragments

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, W.R. [Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL (United Kingdom); Collaboration: La Direction des Sciences de la Matiere du CEA (FR); Le Fonds National de la Recherche Scientifique de Belgique (BE)

    1998-12-31

    High-resolution measurements on {gamma} rays from fission fragments have provided a rich source of information, unobtainable at the moment in any other way, on the spectroscopy of neutron-rich nuclei. In recent years important data have been obtained on the yrast- and near yrast-structure of neutron-rich fission fragments. We discuss the scope of measurements which can be made on prompt gamma rays from secondary fission fragments, the techniques used in the experiments and some results recently obtained. (author) 24 refs., 8 figs., 1 tab.

  9. Fission product release from fuel of water-cooled reactors

    International Nuclear Information System (INIS)

    Strupczewski, A.; Marks, P.; Klisinska, M.

    1997-01-01

    The report contains a review of theoretical models and experimental works of gaseous and volatile fission products from uranium dioxide fuel. The experimental results of activity release at low burnup and the model of fission gas behaviour at initial stage of fuel operational cycle are presented. Empirical models as well as measured results of transient fission products release rate in the temperature up to UO 2 melting point, with consideration of their chemical reactions with fuel and cladding, are collected. The theoretical and experimental data were used for calculations of gaseous and volatile fission products release, especially iodine and caesium, to the gas volume of WWER-1000 and WWER-440 type fuel rods at low and high burnup and their further release from defected rods at the assumed loss-of-coolant accident. (author)

  10. Orexin signaling in rostral lateral hypothalamus and nucleus accumbens shell in the control of spontaneous physical activity in high- and low-activity rats.

    Science.gov (United States)

    Perez-Leighton, Claudio; Little, Morgan R; Grace, Martha; Billington, Charles; Kotz, Catherine M

    2017-03-01

    Spontaneous physical activity (SPA) describes activity outside of formal exercise and shows large interindividual variability. The hypothalamic orexin/hypocretin peptides are key regulators of SPA. Orexins drive SPA within multiple brain sites, including rostral lateral hypothalamus (LH) and nucleus accumbens shell (NAcSh). Rats with high basal SPA (high activity, HA) show higher orexin mRNA expression and SPA after injection of orexin-A in rostral LH compared with low-activity (LA) rats. Here, we explored the contribution of orexin signaling in rostral LH and NAcSh to the HA/LA phenotype. We found that HA rats have higher sensitivity to SPA after injection of orexin-A in rostral LH, but not in NAcSh. HA and LA rats showed similar levels of orexin receptor expression in rostral LH, and activation of orexin-producing neurons after orexin-A injection in rostral LH. Also, in HA and LA rats, the coinjection of orexin-A in rostral LH and NAcSh failed to further increase SPA beyond the effects of orexin-A in rostral LH. Pretreatment with muscimol, a GABA A receptor agonist, in NAcSh potentiated SPA produced by orexin-A injection in rostral LH in HA but not in LA rats. Our results suggest that a feedback loop from orexin-responsive neurons in rostral LH to orexin neurons and a the NAcSh-orexin neuron-rostral LH circuit regulate SPA. Overall, our data suggest that differences in orexin sensitivity in rostral LH and its modulation by GABA afferents from NAcSh contribute to individual SPA differences. Copyright © 2017 the American Physiological Society.

  11. Simulated fissioning of uranium and testing of the fission-track dating method

    Science.gov (United States)

    McGee, V.E.; Johnson, N.M.; Naeser, C.W.

    1985-01-01

    A computer program (FTD-SIM) faithfully simulates the fissioning of 238U with time and 235U with neutron dose. The simulation is based on first principles of physics where the fissioning of 238U with the flux of time is described by Ns = ??f 238Ut and the fissioning of 235U with the fluence of neutrons is described by Ni = ??235U??. The Poisson law is used to set the stochastic variation of fissioning within the uranium population. The life history of a given crystal can thus be traced under an infinite variety of age and irradiation conditions. A single dating attempt or up to 500 dating attempts on a given crystal population can be simulated by specifying the age of the crystal population, the size and variation in the areas to be counted, the amount and distribution of uranium, the neutron dose to be used and its variation, and the desired ratio of 238U to 235U. A variety of probability distributions can be applied to uranium and counting-area. The Price and Walker age equation is used to estimate age. The output of FTD-SIM includes the tabulated results of each individual dating attempt (sample) on demand and/or the summary statistics and histograms for multiple dating attempts (samples) including the sampling age. An analysis of the results from FTD-SIM shows that: (1) The external detector method is intrinsically more precise than the population method. (2) For the external detector method a correlation between spontaneous track count, Ns, and induced track count, Ni, results when the population of grains has a stochastic uranium content and/or when the counting areas between grains are stochastic. For the population method no correlation can exist. (3) In the external detector method the sampling distribution of age is independent of the number of grains counted. In the population method the sampling distribution of age is highly dependent on the number of grains counted. (4) Grains with zero-track counts, either in Ns or Ni, are in integral part of

  12. Theory of nuclear fission: a review

    International Nuclear Information System (INIS)

    Mosel, U.

    1976-01-01

    General properties of nuclear fission are reviewed and related to our present knowledge of fission theory. For this purpose the basic reasons for the shape of the fission barriers are discussed and their consequences compared with experimental results on barrier shapes and structures. Special emphasis is put on the asymmetry of the fission barriers and mass-distributions and its relation to the shells of the nascent fragment shells. Finally the problem of calculating fission cross sections is discussed

  13. International handling of fissionable material

    International Nuclear Information System (INIS)

    1975-01-01

    The opinion of the ministry for foreign affairs on international handling of fissionable materials is given. As an introduction a survey is given of the possibilities to produce nuclear weapons from materials used in or produced by power reactors. Principles for international control of fissionable materials are given. International agreements against proliferation of nuclear weapons are surveyed and methods to improve them are proposed. (K.K.)

  14. A new look at statistics in fission-track dating

    International Nuclear Information System (INIS)

    Green, P.F.

    1981-01-01

    Poissonian errors, as routinely applied in fission-track dating, represent a limiting case, which may not always be attainable in practice. Other experimental factors may introduce additional non-Poissonian errors, which must be taken into account. In the population method, sampling of non-homogeneous uranium distributions introduces experimental error. In the external detector method (EDM), many factors exist to introduce such error. Simply quoting total numbers of spontaneous and induced fission tracks obtained by the EDM may disguise the possible influence of experimental variation. The present work concentrates on the EDM, and describes a test which has recently been proposed to detect the presence of experimental error in EDM analyses. The question of an alternative analysis for cases where such error is present is also considered. A method of presenting EDM data is suggested, which allows assessment of the importance of experimental errors. (author)

  15. Fission-neutrons source with fast neutron-emission timing

    Energy Technology Data Exchange (ETDEWEB)

    Rusev, G., E-mail: rusev@lanl.gov; Baramsai, B.; Bond, E.M.; Jandel, M.

    2016-05-01

    A neutron source with fast timing has been built to help with detector-response measurements. The source is based on the neutron emission from the spontaneous fission of {sup 252}Cf. The time is provided by registering the fission fragments in a layer of a thin scintillation film with a signal rise time of 1 ns. The scintillation light output is measured by two silicon photomultipliers with rise time of 0.5 ns. Overall time resolution of the source is 0.3 ns. Design of the source and test measurements using it are described. An example application of the source for determining the neutron/gamma pulse-shape discrimination by a stilbene crystal is given.

  16. Radiochemistry and the Study of Fission

    Energy Technology Data Exchange (ETDEWEB)

    Rundberg, Robert S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-11-14

    These are slides from a lecture given at UC Berkeley. Radiochemistry has been used to study fission since its discovery. Radiochemical methods are used to determine cumulative mass yields. These measurements have led to the two-mode fission hypothesis to model the neutron energy dependence of fission product yields. Fission product yields can be used for the nuclear forensics of nuclear explosions. The mass yield curve depends on both the fuel and the neutron spectrum of a device. Recent studies have shown that the nuclear structure of the compound nucleus can affect the mass yield distribution. The following topics are covered: In the beginning: the discovery of fission; forensics using fission products: what can be learned from fission products, definitions of R-values and Q-values, fission bases, K-factors and fission chambers, limitations; the neutron energy dependence of the mass yield distribution (the two mode fission hypothesis); the influence of nuclear structure on the mass yield distribution. In summary: Radiochemistry has been used to study fission since its discovery. Radiochemical measurement of fission product yields have provided the highest precision data for developing fission models and for nuclear forensics. The two-mode fission hypothesis provides a description of the neutron energy dependence of the mass yield curve. However, data is still rather sparse and more work is needed near second and third chance fission. Radiochemical measurements have provided evidence for the importance of nuclear states in the compound nucleus in predicting the mass yield curve in the resonance region.

  17. Radiochemistry and the Study of Fission

    International Nuclear Information System (INIS)

    Rundberg, Robert S.

    2016-01-01

    These are slides from a lecture given at UC Berkeley. Radiochemistry has been used to study fission since its discovery. Radiochemical methods are used to determine cumulative mass yields. These measurements have led to the two-mode fission hypothesis to model the neutron energy dependence of fission product yields. Fission product yields can be used for the nuclear forensics of nuclear explosions. The mass yield curve depends on both the fuel and the neutron spectrum of a device. Recent studies have shown that the nuclear structure of the compound nucleus can affect the mass yield distribution. The following topics are covered: In the beginning: the discovery of fission; forensics using fission products: what can be learned from fission products, definitions of R-values and Q-values, fission bases, K-factors and fission chambers, limitations; the neutron energy dependence of the mass yield distribution (the two mode fission hypothesis); the influence of nuclear structure on the mass yield distribution. In summary: Radiochemistry has been used to study fission since its discovery. Radiochemical measurement of fission product yields have provided the highest precision data for developing fission models and for nuclear forensics. The two-mode fission hypothesis provides a description of the neutron energy dependence of the mass yield curve. However, data is still rather sparse and more work is needed near second and third chance fission. Radiochemical measurements have provided evidence for the importance of nuclear states in the compound nucleus in predicting the mass yield curve in the resonance region.

  18. Role of FAT/CD36 in novel PKC isoform activation in heart of spontaneously hypertensive rats

    Czech Academy of Sciences Publication Activity Database

    Klevstig, M. J.; Marková, I.; Burianová, J.; Kazdová, L.; Pravenec, Michal; Nováková, O.; Novák, F.

    2011-01-01

    Roč. 357, 1-2 (2011), s. 163-169 ISSN 0300-8177 R&D Projects: GA ČR(CZ) GD305/08/H037; GA MŠk(CZ) ME08006 Grant - others:Univerzita Karlova(CZ) SVV33779266 Institutional research plan: CEZ:AV0Z50110509 Keywords : CD36 * novel PKC * spontaneously hypertensive rat * insulin resistance Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition Impact factor: 2.057, year: 2011

  19. Status of fission power

    International Nuclear Information System (INIS)

    Levenson, M.

    1977-01-01

    Fission energy is reviewed from the viewpoints of technology, economics, politics, manufacturers, consumers, and foreign countries. Technically, the reactor program is operating and the light water reactor industry shows signs of maturing, although recent business has been disappointing. Marketing of gas-cooled reactors depends, not on technical, but economic and political issues. Liquid metal fast breeder reactors have been demonstrated worldwide, while the gas-cooled fast breeder remains an undemonstrated option. Nuclear plants, currently costing the same as coal plants with scrubbers, are the cheapest option for utilities because most of the cost is imbedded. The defeat of nuclear initiatives in seven states indicates that public feeling is not as anti-nuclear as opponents to nuclear power claim. The harshness of last winter demonstrated the advantages of a power source that is not so sensitive to the weather for reliable operation and transport, as well as low cost energy. Other nations are proceeding to build a nuclear capability, which the U.S. may jeopardize because of concerns about the fuel cycle, nuclear waste disposal, uranium reserves, and nuclear proliferation

  20. Separation of fission Molybdenum for production of technetium generator

    International Nuclear Information System (INIS)

    Bayat, L.; Shaham, V.; Davarkha, R.

    2002-01-01

    There are two basically different methods for Mo-99 productions: Activation of Mo-99 contained at about 24% in natural isotopic mixtures. Mo-98 enriched targets are irradiated in high-flux reactors in order to achieve the highest possible specific activity of the product. Idolisation of fission molybdenum from irradiated nuclear fuel targets which have undergone short-term cooling. Maximum fission yield can be attained by irradiation of uranium-235 with the highest possible enrichment. On account of its approximately 1000 times higher specific activity. Fission molybdenum has almost replaced worldwide the product fabricated by activation. However, fission molybdenum-99 production has as its prerequisite a suitably advanced technology by which the production process taking place under high activity conditions can be controlled. An integral part of the process consist in the retention of the fission gases the recycling of non-consumed fuel and the treatment of the waste streams arising. This publication will deal with the individual steps in the process

  1. Aspirin-induced AMP-activated protein kinase activation regulates the proliferation of vascular smooth muscle cells from spontaneously hypertensive rats

    Energy Technology Data Exchange (ETDEWEB)

    Sung, Jin Young [Department of Pharmacology, College of Medicine, Yeungnam University, Daegu 705-717 (Korea, Republic of); Choi, Hyoung Chul, E-mail: hcchoi@med.yu.ac.kr [Department of Pharmacology, College of Medicine, Yeungnam University, Daegu 705-717 (Korea, Republic of)

    2011-05-06

    Highlights: {yields} Aspirin-induced AMPK phosphorylation was greater in VSMC from SHR than WKY. {yields} Aspirin-induced AMPK phosphorylation inhibited proliferation of VSMC from SHR. {yields} Low basal AMPK phosphorylation in SHR elicits increased VSMC proliferation. {yields} Inhibition of AMPK restored decreased VSMC proliferation by aspirin in SHR. {yields} Aspirin exerts anti-proliferative effect through AMPK activation in VSMC from SHR. -- Abstract: Acetylsalicylic acid (aspirin), used to reduce risk of cardiovascular disease, plays an important role in the regulation of cellular proliferation. However, mechanisms responsible for aspirin-induced growth inhibition are not fully understood. Here, we investigated whether aspirin may exert therapeutic effects via AMP-activated protein kinase (AMPK) activation in vascular smooth muscle cells (VSMC) from wistar kyoto rats (WKY) and spontaneously hypertensive rats (SHR). Aspirin increased AMPK and acetyl-CoA carboxylase phosphorylation in a time- and dose-dependent manner in VSMCs from WKY and SHR, but with greater efficacy in SHR. In SHR, a low basal phosphorylation status of AMPK resulted in increased VSMC proliferation and aspirin-induced AMPK phosphorylation inhibited proliferation of VSMCs. Compound C, an AMPK inhibitor, and AMPK siRNA reduced the aspirin-mediated inhibition of VSMC proliferation, this effect was more pronounced in SHR than in WKY. In VSMCs from SHR, aspirin increased p53 and p21 expression and inhibited the expression of cell cycle associated proteins, such as p-Rb, cyclin D, and cyclin E. These results indicate that in SHR VSMCs aspirin exerts anti-proliferative effects through the induction of AMPK phosphorylation.

  2. Aspirin-induced AMP-activated protein kinase activation regulates the proliferation of vascular smooth muscle cells from spontaneously hypertensive rats

    International Nuclear Information System (INIS)

    Sung, Jin Young; Choi, Hyoung Chul

    2011-01-01

    Highlights: → Aspirin-induced AMPK phosphorylation was greater in VSMC from SHR than WKY. → Aspirin-induced AMPK phosphorylation inhibited proliferation of VSMC from SHR. → Low basal AMPK phosphorylation in SHR elicits increased VSMC proliferation. → Inhibition of AMPK restored decreased VSMC proliferation by aspirin in SHR. → Aspirin exerts anti-proliferative effect through AMPK activation in VSMC from SHR. -- Abstract: Acetylsalicylic acid (aspirin), used to reduce risk of cardiovascular disease, plays an important role in the regulation of cellular proliferation. However, mechanisms responsible for aspirin-induced growth inhibition are not fully understood. Here, we investigated whether aspirin may exert therapeutic effects via AMP-activated protein kinase (AMPK) activation in vascular smooth muscle cells (VSMC) from wistar kyoto rats (WKY) and spontaneously hypertensive rats (SHR). Aspirin increased AMPK and acetyl-CoA carboxylase phosphorylation in a time- and dose-dependent manner in VSMCs from WKY and SHR, but with greater efficacy in SHR. In SHR, a low basal phosphorylation status of AMPK resulted in increased VSMC proliferation and aspirin-induced AMPK phosphorylation inhibited proliferation of VSMCs. Compound C, an AMPK inhibitor, and AMPK siRNA reduced the aspirin-mediated inhibition of VSMC proliferation, this effect was more pronounced in SHR than in WKY. In VSMCs from SHR, aspirin increased p53 and p21 expression and inhibited the expression of cell cycle associated proteins, such as p-Rb, cyclin D, and cyclin E. These results indicate that in SHR VSMCs aspirin exerts anti-proliferative effects through the induction of AMPK phosphorylation.

  3. A twin Frisch-grid ionization chamber as a selective detector for the delayed gamma-spectroscopy of fission fragments

    Energy Technology Data Exchange (ETDEWEB)

    Gaudefroy, L., E-mail: laurent.gaudefroy@cea.fr [CEA, DAM, DIF, F-91297 Arpajon (France); Roger, T., E-mail: roger@ganil.fr [GANIL, CEA/DSM-CNRS/IN2P3, BP 55027, F-14076 Caen (France); Pancin, J., E-mail: pancin@ganil.fr [GANIL, CEA/DSM-CNRS/IN2P3, BP 55027, F-14076 Caen (France); Spitaels, C. [GANIL, CEA/DSM-CNRS/IN2P3, BP 55027, F-14076 Caen (France); Aupiais, J. [CEA, DAM, DIF, F-91297 Arpajon (France); Mottier, J. [Institut de Physique Nucléaire, Université Paris-Sud-11-CNRS-IN2P3, F-91406 Orsay (France)

    2017-05-21

    We present a twin Frisch-grid ionization chamber. The detector is meant to provide high selective power for the study of delayed gamma-ray spectroscopy of fission fragments produced via {sup 252}Cf spontaneous fission. A mean energy resolution on the kinetic energy of fission fragments of 675 keV (FWHM) is achieved and allows us to resolve masses of fragments for fission events where neutron emission is not energetically possible. The mean mass resolution measured for these particular events amounts to 0.54 mass units (FWHM). For fission events with neutron emission a resolution of 4 mass units (FWHM) is reported. Information on fragment emission angle is measured with a resolution of 0.1 on the difference of the cosines determined for both halves of the detector. A charge resolution of 4.5 charge units (FWHM) is also demonstrated.

  4. Spectroscopy of neutron rich nuclei using cold neutron induced fission of actinide targets at the ILL: The EXILL campaign

    Directory of Open Access Journals (Sweden)

    Blanc A.

    2013-12-01

    Full Text Available One way to explore exotic nuclei is to study their structure by performing γ-ray spectroscopy. At the ILL, we exploit a high neutron flux reactor to induce the cold fission of actinide targets. In this process, fission products that cannot be accessed using standard spontaneous fission sources are produced with a yield allowing their detailed study using high resolution γ-ray spectroscopy. This is what was pursued at the ILL with the EXILL (for EXOGAM at the ILL campaign. In the present work, the EXILL setup and performance will be presented.

  5. Effects of the radiation gamma on the activity and selectivity of the Al2 O3 in the retention of uranium and fission products

    International Nuclear Information System (INIS)

    Duran B, J.M.

    1996-01-01

    The study that here comes constitute a contribution for the treatment of based on waste the properties of retention of the inorganic oxides. The effect induced of the radiation has been determined gamma of the 60 Co in the Al 2 O 3 and their influence in their capacity of retention of uranium and products of fission of watery solutions strongly alkaline. In order to obtain useful information it made the superficial characterizations, structural, crystalline and of retention by means of the techniques of superficial adsorption, spectroscopy infrared, rays-X diffraction, liquid twinkling and γ- spectrometry. The obtained results show that the treatment of the Al 2 O 3 this associated with slight changes in their structural characteristics and superficialities concluding that the molecular water present in the crystalline net of the oxide was not displaced radiolytic for effect, but rather, this spread in the volume of the oxide, blocking the change in the contribution to crystalline of the oxide. (Author)

  6. Advances on fission chamber modelling

    International Nuclear Information System (INIS)

    Filliatre, Philippe; Jammes, Christian; Geslot, Benoit; Veenhof, Rob

    2013-06-01

    In-vessel, online neutron flux measurements are routinely performed in mock-up and material testing reactors by fission chambers. Those measurements have a wide range of applications, including characterization of experimental conditions, reactor monitoring and safety. Depending on the application, detectors may experience a wide range of constraints, of several magnitudes, in term of neutron flux, gamma-ray flux, temperature. Hence, designing a specific fission chamber and measuring chain for a given application is a demanding task. It can be achieved by a combination of experimental feedback and simulating tools, the latter being based on a comprehensive understanding of the underlying physics. A computation route that simulates fission chambers, named CHESTER, is presented. The retrieved quantities of interest are the neutron-induced charge spectrum, the electronic and ionic pulses, the mean current and variance, the power spectrum. It relies on the GARFIELD suite, originally developed for drift chambers, and makes use of the MAGBOLTZ code to assess the drift parameters of electrons within the filling gas, and the SRIM code to evaluate the stopping range of fission products. The effect of the gamma flux is also estimated. Computations made with several fission chambers exemplify the possibilities of the route. A good qualitative agreement is obtained when comparing the results with the experimental data available to date. In a near future, a comprehensive experimental programme will be undertaken to qualify the route using the known neutron sources, mock-up reactors and wide choice of fission chambers, with a stress on the predictiveness of the Campbelling mode. Depending on the results, a refinement of the modelling and an effort on the accuracy of input data are also to be considered. CHESTER will then make it possible to predict the overall sensitivity of a chamber, and to optimize the design for a given application. Another benefit will be to increase the

  7. Comparative study of the antihypertensive activity of Marrubium vulgare and of the dihydropyridine calcium antagonist amlodipine in spontaneously hypertensive rat.

    Science.gov (United States)

    El Bardai, Sanae; Lyoussi, Badiaa; Wibo, Maurice; Morel, Nicole

    2004-08-01

    Water extract of Marrubium vulgare is widely used as antihypertensive treatment in folk medicine. We have compared the effect of 10-week-long treatment with amlodipine or Marrubium water extract on systolic blood pressure (SBP), cardiovascular remodeling and vascular relaxation in spontaneously hypertensive rats (SHR). Both treatments produced similar decrease in SBP. Amlodipine treatment reduced left ventricle, aortic and mesenteric artery weight. Marrubium treatment had a significant antihypertrophic effect in aorta only. Relaxation to acetylcholine (ACh) of mesenteric artery was improved by Marrubium but not by amlodipine treatment. These results demonstrate that, in addition to its antihypertensive effect, Marrubium water extract improved the impaired endothelial function in SHR.

  8. The latest progress of fission track analysis

    International Nuclear Information System (INIS)

    Wang Shicheng

    1996-01-01

    Fission track analysis as a new nuclear track technique is based on fission track annealing in mineral and is used for oil and gas exploration successfully. The west part of China is the main exploration for oil and gas. The oil and gas basins there experienced much more complicated thermal history and higher paleotemperature. In order to apply fission track analysis to these basins, following work was be carried out: 1. The decomposition of grain age distribution of zircon fission tracks. 2. Study on thermal history of Ordos basin using zircon fission track analysis. 3. The fission track study on the Qiang Tang basin in tibet

  9. Electrical Responses and Spontaneous Activity of Human iPS-Derived Neuronal Networks Characterized for 3-month Culture with 4096-Electrode Arrays.

    Science.gov (United States)

    Amin, Hayder; Maccione, Alessandro; Marinaro, Federica; Zordan, Stefano; Nieus, Thierry; Berdondini, Luca

    2016-01-01

    The recent availability of human induced pluripotent stem cells (hiPSCs) holds great promise as a novel source of human-derived neurons for cell and tissue therapies as well as for in vitro drug screenings that might replace the use of animal models. However, there is still a considerable lack of knowledge on the functional properties of hiPSC-derived neuronal networks, thus limiting their application. Here, upon optimization of cell culture protocols, we demonstrate that both spontaneous and evoked electrical spiking activities of these networks can be characterized on-chip by taking advantage of the resolution provided by CMOS multielectrode arrays (CMOS-MEAs). These devices feature a large and closely-spaced array of 4096 simultaneously recording electrodes and multi-site on-chip electrical stimulation. Our results show that networks of human-derived neurons can respond to electrical stimulation with a physiological repertoire of spike waveforms after 3 months of cell culture, a period of time during which the network undergoes the expression of developing patterns of spontaneous spiking activity. To achieve this, we have investigated the impact on the network formation and on the emerging network-wide functional properties induced by different biochemical substrates, i.e., poly-dl-ornithine (PDLO), poly-l-ornithine (PLO), and polyethylenimine (PEI), that were used as adhesion promoters for the cell culture. Interestingly, we found that neuronal networks grown on PDLO coated substrates show significantly higher spontaneous firing activity, reliable responses to low-frequency electrical stimuli, and an appropriate level of PSD-95 that may denote a physiological neuronal maturation profile and synapse stabilization. However, our results also suggest that even 3-month culture might not be sufficient for human-derived neuronal network maturation. Taken together, our results highlight the tight relationship existing between substrate coatings and emerging network

  10. Thorium-uranium fission radiography

    Science.gov (United States)

    Haines, E. L.; Weiss, J. R.; Burnett, D. S.; Woolum, D. S.

    1976-01-01

    Results are described for studies designed to develop routine methods for in-situ measurement of the abundance of Th and U on a microscale in heterogeneous samples, especially rocks, using the secondary high-energy neutron flux developed when the 650 MeV proton beam of an accelerator is stopped in a 42 x 42 cm diam Cu cylinder. Irradiations were performed at three different locations in a rabbit tube in the beam stop area, and thick metal foils of Bi, Th, and natural U as well as polished silicate glasses of known U and Th contents were used as targets and were placed in contact with mica which served as a fission track detector. In many cases both bare and Cd-covered detectors were exposed. The exposed mica samples were etched in 48% HF and the fission tracks counted by conventional transmitted light microscopy. Relative fission cross sections are examined, along with absolute Th track production rates, interaction tracks, and a comparison of measured and calculated fission rates. The practicality of fast neutron radiography revealed by experiments to data is discussed primarily for Th/U measurements, and mixtures of other fissionable nuclei are briefly considered.

  11. Change over from compound nuclear fission to quasi-fission

    International Nuclear Information System (INIS)

    Ghosh, T. K.; Banerjee, K.; Bhattacharya, C.; Bhattacharya, S.; Kundu, S.; Meena, J. K.; Mukherjee, G.; Mukhopadhyay, S.; Rana, T. K.; Golda, K. S.; Bhattacharya, P.

    2010-01-01

    Fission fragment mass distribution has been measured from the decay of 246 Bk nucleus populating via two entrance channels with slight difference in mass asymmetries but belonging on either side of the Businaro Gallone mass asymmetry parameter. Both the target nuclei were deformed. Near the Coulomb barrier, at similar excitation energies the width of the fission fragment mass distribution was found to be drastically different for the 14 N+ 232 Th reaction compared to the 11 B+ 235 U reaction. The entrance channel mass asymmetry was found to affect the fusion process sharply. (authors)

  12. Change over from compound nuclear fission to quasi-fission

    Directory of Open Access Journals (Sweden)

    Bhattacharya P.

    2010-03-01

    Full Text Available Fission fragment mass distribution has been measured in two reactions to populate compound nucleus 246Bk. Both the target nuclei were deformed. However, entrance channel mass asymmetry of the two systems was on the either side of the Businaro Gallone mass asymmetry parameter. Near the Coulomb barrier, at similar excitation energies, the width of the fission fragment mass distribution was found to be significantly different for the 14N+232Th reaction compared to the 11B+235U reaction. The entrance channel mass asymmetry was found to play a significant role in deciding the fusion process.

  13. Nuclear fission and neutron-induced fission cross-sections

    CERN Document Server

    James, G D; Michaudon, A; Michaudon, A; Cierjacks, S W; Chrien, R E

    2013-01-01

    Nuclear Fission and Neutron-Induced Fission Cross-Sections is the first volume in a series on Neutron Physics and Nuclear Data in Science and Technology. This volume serves the purpose of providing a thorough description of the many facets of neutron physics in different fields of nuclear applications. This book also attempts to bridge the communication gap between experts involved in the experimental and theoretical studies of nuclear properties and those involved in the technological applications of nuclear data. This publication will be invaluable to those interested in studying nuclear fis

  14. Experimental investigation on spontaneously active hippocampal cultures recorded by means of high-density MEAs: analysis of the spatial resolution effects

    Directory of Open Access Journals (Sweden)

    Alessandro Maccione

    2010-05-01

    Full Text Available Based on experiments performed with high-resolution Active Pixel Sensor microelectrode arrays (APS-MEAs coupled with spontaneously active hippocampal cultures, this work investigates the spatial resolution effects of the neuroelectronic interface on the analysis of the recorded electrophysiological signals. The adopted methodology consists, first, in recording the spontaneous activity at the highest spatial resolution (inter-electrode separation of 21 µm from the whole array of 4096 microelectrodes. Then, the full resolution dataset is spatially down sampled in order to evaluate the effects on raster plot representation, array-wide spike rate (AWSR, mean firing rate (MFR and mean bursting rate (MBR. Furthermore, the effects of the array-to-network relative position are evaluated by shifting a subset of equally spaced electrodes on the entire recorded area. Results highlight that MFR and MBR are particularly influenced by the spatial resolution provided by the neuroelectronic interface. On high-resolution large MEAs, such analysis better represent the time-based parameterization of the network dynamics. Finally, this work suggest interesting capabilities of high-resolution MEAs for spatial-based analysis in dense and low-dense neuronal preparation for investigating signalling at both local and global neuronal circuitries.

  15. Ternary Fission of {sup 249}Cf(n,f) and {sup 250}Cf(SF)

    Energy Technology Data Exchange (ETDEWEB)

    University of Gent, B-9000 Gent, Belgium; CEA Cadarache, F-13108 Saint-Paul-lez-Durance, France; Institute Laue-Langevin, F-38042 Grenoble, France; EC-JRC Institute for Reference Materials and Measurements, B-2440 Geel, Belgium; Wadsworth Center, New York State Department of Health, Albany NY 12201, USA; Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Vermote, S.; Wagemans, C.; Serot, O.; Soldner, T.; Geltenbort, P.; Gils, J. Van; Almahamid, I.; Tian, G.; Rao, L.

    2011-09-01

    During the last years, several Cm and Cf isotopes have been studied by our research group in the frame of a systematic investigation of gas emission characteristics in ternary fission. Here we report on new results on the energy distribution and the emission probability of {sup 3}H, {sup 4}He and {sup 6}He particles emitted in the spontaneous ternary fission of {sup 250}Cf (E{sub exc} = 0 MeV) and in the neutron induced ternary fission of {sup 249}Cf (E{sub exc} = 6.625 MeV). Both measurements were performed using suited and well-calibrated ΔE-E telescope detectors, at the IRMM (Geel, Belgium) for the spontaneous fission and at the very intense neutron beam PF1b at the Institute Laue-Langevin (Grenoble, France) for the neutron induced fission measurement. In this way, the existing database can be enlarged with new results for Z=98 isotopes, which is important for the systematic investigation. Moreover, the investigation of the 'isotope couple' {sup 249}Cf(n,f) - {sup 250}Cf(SF), together with corresponding data for other isotopes, will yield valuable information on the influence of the excitation energy on the particle emission probabilities.

  16. Involvement of cyclic nucleotide-gated channels in spontaneous activity generated in isolated interstitial cells of Cajal from the rabbit urethra.

    Science.gov (United States)

    Sancho, Maria; Bradley, Eamonn; Garcia-Pascual, Angeles; Triguero, Domingo; Thornbury, Keith D; Hollywood, Mark A; Sergeant, Gerard P

    2017-11-05

    Cyclic nucleotide-gated (CNG) channels are non-selective cation channels that mediate influx of extracellular Na + and Ca 2+ in various cell types. L-cis-Diltiazem, a CNG channel blocker, inhibits contraction of urethral smooth muscle (USM), however the mechanisms underlying this effect are still unclear. We investigated the possibility that CNG channels contribute to spontaneous pacemaker activity in freshly isolated interstitial cells of Cajal (ICC) isolated from the rabbit urethra (RUICC). Using immunocytochemistry, we found intense CNG1-immunoreactivity in vimentin-immunoreactive RUICC, mainly within patches of the cellular body and processes. In contrast, α-actin immunoreactive smooth muscle cells (SMC) did not show significant reactivity to a specific CNGA1 antibody. Freshly isolated RUICC, voltage clamped at -60mV, developed spontaneous transient inward currents (STICs) that were inhibited by L-cis-Diltiazem (50µM). Similarly, L-cis-Diltiazem (50µM) also inhibited Ca 2+ waves in isolated RUICC, recorded using a Nipkow spinning disk confocal microscope. L-cis-Diltiazem (50µM) did not affect caffeine (10mM)-induced Ca 2+ transients, but significantly reduced phenylephrine-evoked Ca 2+ oscillations and inward currents in in RUICC. L-type Ca 2+ current amplitude in isolated SMC was reduced by ~18% in the presence of L-cis-Diltiazem (50µM), however D-cis-Diltiazem, a recognised L-type Ca 2+ channel blocker, abolished L-type Ca 2+ current but did not affect Ca 2+ waves or STICs in RUICC. These results indicate that the effects of L-cis-diltiazem on rabbit USM could be mediated by inhibition of CNG1 channels that are present in urethral ICC and therefore CNG channels contribute to spontaneous activity in these cells. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Production Pathways and Separation Procedures for High-Diagnostic-Value Activation Species, Fission Products, and Actinides Required for Preparation of Realistic Synthetic Post-Detonation Nuclear Debris: Status Report and FY16 Project Plan

    Energy Technology Data Exchange (ETDEWEB)

    Faye, S. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Shaughnessy, D. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-08-19

    The objective of this project is to provide a comprehensive study on the production routes and chemical separation requirements for activation products, fission products, and actinides required for the creation of realistic post-detonation surrogate debris. Isotopes that have been prioritized by debris diagnosticians will be examined for their ability to be produced at existing irradiation sources, production rates, and availability of target materials, and chemical separation procedures required to rapidly remove the products from the bulk target matrix for subsequent addition into synthetic debris samples. The characteristics and implications of the irradiation facilities on the isotopes of interest will be addressed in addition to a summary of the isotopes that are already regularly produced. This is a planning document only.

  18. Fissioning universe: Topological inflation and Kaluza-Klein cosmologies

    Energy Technology Data Exchange (ETDEWEB)

    Kaku, Michio; Lykken, J.

    1986-05-05

    We propose a Kaluza-Klein cosmology by reversing the usual scenario: instead of starting with a flat 4+N dimensional universe in which N of the dimensions curl up into a compact manifold, we start with a compact 3+N dimensional manifold in which 3 of the dimensions are allowed to peel off and expand into the known universe. We reverse the usual ''spontaneous compactification'' scenario begin with a closed manifold Msup(3+N) which undergoes ''spontaneous fissioning'' into a product manifold M/sup 3/xMsup(N). Remarkably, the 3-dimensional universe M/sup 3/ can undergo a rapid de Sitter expansion large enough to solve the horizon and flatness problem. We call this ''topological inflation'', which we propose as an alternative to the usual GUT inflation. The inflationary phase automatically terminates into a big bang phase. (orig.).

  19. The fissioning universe: Topological inflation and Kaluza-Klein cosmologies

    International Nuclear Information System (INIS)

    Kaku, Michio; Lykken, J.

    1986-01-01

    We propose a Kaluza-Klein cosmology by reversing the usual scenario: instead of starting with a flat 4+N dimensional universe in which N of the dimensions curl up into a compact manifold, we start with a compact 3+N dimensional manifold in which 3 of the dimensions are allowed to peel off and expand into the known universe. We reverse the usual ''spontaneous compactification'' scenario begin with a closed manifold Msup(3+N) which undergoes ''spontaneous fissioning'' into a product manifold M 3 xMsup(N). Remarkably, the 3-dimensional universe M 3 can undergo a rapid de Sitter expansion large enough to solve the horizon and flatness problem. We call this ''topological inflation'', which we propose as an alternative to the usual GUT inflation. The inflationary phase automatically terminates into a big bang phase. (orig.)

  20. Study of Deposit Cesium-137 (137Cs Activity as a Result of Fission Product from The Fukushima Daiichi Nuclear Power Plant at Japan after Earthquake and Tsunami in 2011

    Directory of Open Access Journals (Sweden)

    Rahpita Windriani

    2014-10-01

    Full Text Available Study of deposit Cesium-137 (137Cs activity as a result of the fission product of Fukushima Daiichi Nuclear Power Plant after earthquake and tsunami in 2011 has been done. The purpose of the present research is to study the deposit 137Cs activity on the land and the Sea of Japan and then to estimate a model of 137Cs distribution on the earth's surface of Japan. The stability of nuclei decay equation is used to obtain a deposit 137Cs activity depending on time, theoretically. The Pasquill-Gifford equation is used to estimate a distribution of 137Cs activity on the earth surface from the original source. The results suggested that Hatachinaka city, the largest measurement point, for about 60 years forward, 137Cs activity levels reach about 54 Bq. In the Sea of Japan at the point of sensor C47, which it has the largest value, the accumulation of deposit 137Cs activity gives about 0.69 Bq at the time of the next 60 years. For the distribution of 137Cs activity, the concentration values at a distance of 200 m from the original source obtained maximum for all case.

  1. Dating by fission track method: study of neutron dosimetry with natural uranium thin films; Datacao com o metodo dos tracos de fissao: estudo da dosimetria de neutrons com filmes finos de uranio natural

    Energy Technology Data Exchange (ETDEWEB)

    Iunes, P.J.

    1990-06-01

    Fission track dating is described, focalizing the problem of the decay constant for spontaneous fission of {sup 238} U and the use of neutron dosimetry in fission track analysis. Experimental procedures using thin films of natural uranium as neutron dosimeters and its results are presented. The author shows a intercomparison between different thin films and between the dosimetry with thin film and other dosimetries. (M.V.M.). 52 refs, 12 figs, 9 tabs.

  2. NEACRP thermal fission product benchmark

    International Nuclear Information System (INIS)

    Halsall, M.J.; Taubman, C.J.

    1989-09-01

    The objective of the thermal fission product benchmark was to compare the range of fission product data in use at the present time. A simple homogeneous problem was set with 200 atoms H/1 atom U235, to be burnt up to 1000 days and then decay for 1000 days. The problem was repeated with 200 atoms H/1 atom Pu239, 20 atoms H/1 atom U235 and 20 atoms H/1 atom Pu239. There were ten participants and the submissions received are detailed in this report. (author)

  3. Search for Singlet Fission Chromophores

    Energy Technology Data Exchange (ETDEWEB)

    Havlas, Z.; Akdag, A.; Smith, M. B.; Dron, P.; Johnson, J. C.; Nozik, A. J.; Michl, J.

    2012-01-01

    Singlet fission, in which a singlet excited chromophore shares its energy with a ground-state neighbor and both end up in their triplet states, is of potential interest for solar cells. Only a handful of compounds, mostly alternant hydrocarbons, are known to perform efficiently. In view of the large number of conditions that a successful candidate for a practical cell has to meet, it appears desirable to extend the present list of high performers to additional classes of compounds. We have (i) identified design rules for new singlet fission chromophores and for their coupling to covalent dimers, (ii) synthesized them, and (iii) evaluated their performance as neat solids or covalent dimers.

  4. Effect of galantamine on the human α7 neuronal nicotinic acetylcholine receptor, the Torpedo nicotinic acetylcholine receptor and spontaneous cholinergic synaptic activity

    Science.gov (United States)

    Texidó, Laura; Ros, Esteve; Martín-Satué, Mireia; López, Susana; Aleu, Jordi; Marsal, Jordi; Solsona, Carles

    2005-01-01

    Various types of anticholinesterasic agents have been used to improve the daily activities of Alzheimer's disease patients. It was recently demonstrated that Galantamine, described as a molecule with anticholinesterasic properties, is also an allosteric enhancer of human α4β2 neuronal nicotinic receptor activity. We explored its effect on the human α7 neuronal nicotinic acetylcholine receptor (nAChR) expressed in Xenopus oocytes. Galantamine, at a concentration of 0.1 μM, increased the amplitude of acetylcholine (ACh)-induced ion currents in the human α7 nAChR expressed in Xenopus oocytes, but caused inhibition at higher concentrations. The maximum effect of galantamine, an increase of 22% in the amplitude of ACh-induced currents, was observed at a concentration of 250 μM Ach. The same enhancing effect was obtained in oocytes transplanted with Torpedo nicotinic acetylcholine receptor (AChR) isolated from the electric organ, but in this case the optimal concentration of galantamine was 1 μM. In this case, the maximum effect of galantamine, an increase of 35% in the amplitude of ACh-induced currents, occurred at a concentration of 50 μM ACh. Galantamine affects not only the activity of post-synaptic receptors but also the activity of nerve terminals. At a concentration of 1 μM, quantal spontaneous events, recorded in a cholinergic synapse, increased their amplitude, an effect which was independent of the anticholinesterasic activity associated with this compound. The anticholinesterasic effect was recorded in preparations treated with a galantamine concentration of 10 μM. In conclusion, our results show that galantamine enhances human α7 neuronal nicotinic ACh receptor activity. It also enhances muscular AChRs and the size of spontaneous cholinergic synaptic events. However, only a very narrow range of galantamine concentrations can be used for enhancing effects. PMID:15834443

  5. Fast-neutron-induced fission of 242Pu at nELBE

    Directory of Open Access Journals (Sweden)

    Kögler Toni

    2017-01-01

    Full Text Available The fast neutron-induced fission cross section of 242Pu was determined in the range of 0.5 MeV to 10 MeV relative to 235U(n,f at the neutron time-of-flight facility nELBE. The number of target nuclei was calculated by means of measuring the spontaneous fission rate of 242Pu. Neutron transport simulations with Geant4 and MCNP6 are used to correct the relative cross section for neutron scattering. The determined results are in good agreement with current experimental and evaluated data sets.

  6. Fuel performance and fission product behaviour in gas cooled reactors

    International Nuclear Information System (INIS)

    1997-11-01

    The Co-ordinated Research Programme (CRP) on Validation of Predictive Methods for Fuel and Fission Product Behaviour was organized within the frame of the International Working Group on Gas Cooled Reactors. This International Working Group serves as a forum for exchange of information on national programmes, provides advice to the IAEA on international co-operative activities in advanced technologies of gas cooled reactors (GCRs), and supports the conduct of these activities. The objectives of this CRP were to review and document the status of the experimental data base and of the predictive methods for GCR fuel performance and fission product behaviour; and to verify and validate methodologies for the prediction of fuel performance and fission product transport

  7. Effect of effective mass and spontaneous polarization on photocatalytic activity of wurtzite and zinc-blende ZnS

    Directory of Open Access Journals (Sweden)

    Ming Dong

    2015-10-01

    Full Text Available Semiconductor zinc sulphide (ZnS has two common phases: hexagonal wurtzite and cubic zinc-blende structures. The crystal structures, energy band structures, density of states (DOS, bond populations, and optical properties of wurtzite and zinc-blende ZnS were investigated by the density functional theory of first-principles. The similar band gaps and DOS of wurtzite and zinc-blende ZnS were found and implied the similarities in crystal structures. However, the distortion of ZnS4 tetrahedron in wurtzite ZnS resulted in the production of spontaneous polarization and internal electric field, which was beneficial for the transfer and separation of photogenerated electrons and holes.

  8. Collective spectra along the fission barrier

    OpenAIRE

    Pigni M. T.; Andreev A. V.; Shneidman T. M.; Massimi C.; Vannini G.; Ventura A.

    2012-01-01

    Discrete and continuous spectra of fissioning nuclei at the humps of fission barriers (Bohr transition states) and in the intermediate wells (superdeformed and hyperdeformed states) play a key role in the calculation of fission cross sections. A theoretical evaluation of the collective parts of the spectra is possible within the framework of the dinuclear system model, which treats the wave function of the fissioning nucleus as a superposition of a mononucleus configuration and two–cluster co...

  9. Altered neuronal spontaneous activity correlates with glutamate concentration in medial prefrontal cortex of major depressed females: An fMRI-MRS study.

    Science.gov (United States)

    Zhang, Xiaoliu; Tang, Yingying; Maletic-Savatic, Mirjana; Sheng, Jianhua; Zhang, Xuanhong; Zhu, Yajing; Zhang, Tianhong; Wang, Junjie; Tong, Shanbao; Wang, Jijun; Li, Yao

    2016-09-01

    Major depressive disorder (MDD) is twice more prevalent in females than in males. Yet, there have only been a few studies on the functional brain activity in female MDD patients and the detailed mechanisms underlying their neurobiology merit further investigations. In the present work, we used combined fMRI-MRS methods to investigate the altered intrinsic neuronal activity and its association with neurotransmitter concentration in female MDD patients. The whole brain amplitude of low frequency fluctuation (ALFF) analysis using resting state functional magnetic resonance imaging (fMRI) was performed to explore the alteration of intrinsic neuronal signals in MDD females (n=11) compared with female healthy controls (n=11). With a specific interest in the medial prefrontal cortex (mPFC) area, we quantified the concentration of amino acid neurotransmitters including GABA ((r-aminobutyric acid)), Glu (Glutamate), and Glx (Glutamate + Glutamine) using (1)H-MRS technology. Moreover, we conducted Pearson correlation analysis between the ALFF value and neurotransmitter concentration to find out the functional-biochemical relation in mPFC area. The relationship between the metabolites concentration and MDD symptomatology was also examined through Spearman correlation analysis. We found that the female MDD patients showed increased neuronal spontaneous activity in left medial prefrontal cortex (mPFC) and left middle frontal cortex, with decreased ALFF level in right putamen and right middle temporal cortex (pconcentration in female MDD patients (r=0.67, p=0.023). The Glu concentration in mPFC was positively correlated with patients HAMA scores (r=0.641, p=0.033). The relatively small sample size, metabolite information acquired only in mPFC and not all patients were unmedicated are the major limitations of our study. Using combined fMRI-MRS methods, we found increased spontaneous neuronal activity was correlated with Glu concentration in mPFC of female MDD patients. Other

  10. Charged particle-induced nuclear fission reactions – Progress and ...

    Indian Academy of Sciences (India)

    progress made in recent years and the prospects in the area of nuclear fission research will be the focus of this review. Keywords. Nuclear fission; charged particle-induced fission; heavy ions; fission angular distribu- tions; mass distributions; fission barrier; moment of inertia; shell effect in fission. PACS Nos 25.70.Jj; 25.85.

  11. Identification and systematical studies of the electron-capture delayed fission (ECDF) in the lead region

    CERN Multimedia

    Pauwels, D B; Lane, J

    2008-01-01

    In our recent experiment (March 2007) at the velocity filter SHIP(GSI) we observed the electron-capture delayed fission of the odd-odd isotope $^{194}$At. This is the first unambiguous identification of this phenomenon in the very neutron-deficient nuclei in the vicinity of the proton shell closure at Z=82. In addition, the total kinetic energy (TKE) for the daughter nuclide $^{194}$Po was measured, despite the fact that this isotope does not decay via spontaneous fission. Semi-empirical analysis of the electron-capture Q$_{EC}$ values and fission barriers B$_{f}$ shows that a relatively broad island of ECDF must exist in this region of the Nuclide Chart, with some of the nuclei having unusually high ECDF probabilities. Therefore, this Proposal is intended to initiate the systematic identification and study of $\\beta$-delayed fission at ISOLDE in the very neutron-deficient lead region. Our aim is to provide unique low-energy fission data (e.g. probabilities, TKE release, fission barriers and their isospin dep...

  12. Recent progress in fission track analysis and its applications in China

    International Nuclear Information System (INIS)

    Wang, S.C.; Kang, T.S.; Jing, G.R.

    1993-01-01

    Fission track analysis (FTA) has been developed and applied in China since 1985. Since then great efforts have been made on methodology and applications. In order to improve the accuracy of fission track dating, zeta calibration constants have been determined against NBS SRM 962 standard uranium glass and seven age standards. TINT method and silver coating were used to increase the density and contrast of confined spontaneous fission tracks on apatite. Based on the fanning model of fission track annealing for apatite presented by Laslett, G.M., a forward computer modeling of track shortening and age evolution was completed and an inverse method of modeling thermal histories from apatite fission track data is underway. Apatite fission track data (age and track length), zircon age and forward modeling method have been used to reveal thermal and tectonic histories of several sedimentary basins and of a collision zone in China. In this presentation some progress in methodology and application will be presented and discussed. (Author)

  13. Development of a thin scintillation films fission-fragment detector and a novel neutron source

    Science.gov (United States)

    Rusev, G.; Jandel, M.; Baramsai, B.; Bond, E. M.; Bredeweg, T. A.; Couture, A.; Daum, J. K.; Favalli, A.; Ianakiev, K. D.; Iliev, M. L.; Mosby, S.; Roman, A. R.; Springs, R. K.; Ullmann, J. L.; Walker, C. L.

    2015-08-01

    Investigation of prompt fission and neutron-capture Υ rays from fissile actinide samples at the Detector for Advanced Neutron Capture Experiments (DANCE) requires use of a fission-fragment detector to provide a trigger or a veto signal. A fission-fragment detector based on thin scintillating films and silicon photomultipliers has been built to serve as a trigger/veto detector in neutron-induced fission measurements at DANCE. The fissile material is surrounded by scintillating films providing a 4π detection of the fission fragments. The scintillations were registered with silicon photomultipliers. A measurement of the 235U(n,f) reaction with this detector at DANCE revealed a correct time-of-flight spectrum and provided an estimate for the efficiency of the prototype detector of 11.6(7)%. Design and test measurements with the detector are described. A neutron source with fast timing has been built to help with detector-response measurements. The source is based on the neutron emission from the spontaneous fission of 252Cf and the same type of scintillating films and silicon photomultipliers. Overall time resolution of the source is 0.3 ns. Design of the source and test measurements with it are described. An example application of the source for determining the neutron/gamma pulse-shape discrimination by a stilbene crystal is given.

  14. A compact multi-plate fission chamber for the simultaneous measurement of 233U capture and fission cross-sections

    Directory of Open Access Journals (Sweden)

    Bacak M.

    2017-01-01

    Full Text Available 233U plays the essential role of fissile nucleus in the Th-U fuel cycle. A particularity of 233U is its small neutron capture cross-section which is about one order of magnitude lower than the fission cross-section on average. Therefore, the accuracy in the measurement of the 233U capture cross-section essentially relies on efficient capture-fission discrimination thus a combined setup of fission and γ-detectors is needed. At CERN n_TOF the Total Absorption Calorimeter (TAC coupled with compact fission detectors is used. Previously used MicroMegas (MGAS detectors showed significant γ-background issues above 100 eV coming from the copper mesh. A new measurement campaign of the 233U capture cross-section and alpha ratio is planned at the CERN n_TOF facility. For this measurement, a novel cylindrical multi ionization cell chamber was developed in order to provide a compact solution for 14 active targets read out by 8 anodes. Due to the high specific activity of 233U fast timing properties are required and achieved with the use of customized electronics and the very fast ionizing gas CF4 together with a high electric field strength. This paper describes the new fission chamber and the results of the first tests with neutrons at GELINA proving that it is suitable for the 233U measurement.

  15. Measurement of fission anisotropy for Ta

    Indian Academy of Sciences (India)

    F on many actinide targets with large deformations exhibit dramatic increase with decreasing energy [5]. In order to understand the data, an admixture of non compound reaction processes, like the fast fission, the quasifission with orientation dependence and the preequilibrium fission, is introduced as a source of fission like ...

  16. Fission fragment mass and angular distributions

    Indian Academy of Sciences (India)

    2015-07-22

    Jul 22, 2015 ... Synthesis of heavy and superheavy elements is severely hindered by fission and fission-like processes. The probability of these fission-like, non-equilibrium processes strongly depends on the entrance channel parameters. This article attempts to summarize the recent experimental findings and classify the ...

  17. Fission yield data evaluation system FYDES

    International Nuclear Information System (INIS)

    Liu Tingjin

    1998-01-01

    Taking account of some features of fission yield data, to do the fission yield data evaluation conveniently, a fission yield data evaluation system FYDES has been developed for last two years. Outline of the system, data retrieval and data table standardization, data correction codes, data averaging code, simultaneous evaluation code and data fit programs were introduced

  18. Charged particle-induced nuclear fission reactions

    Indian Academy of Sciences (India)

    The nuclear fission phenomenon continues to be an enigma, even after nearly 75 years of its discovery. Considerable progress has been made towards understanding the fission process. Both light projectiles and heavy ions have been employed to investigate nuclear fission. An extensive database of the properties of ...

  19. Fission barriers from multidimensionally-constrained covariant density functional theories

    Directory of Open Access Journals (Sweden)

    Lu Bing-Nan

    2017-01-01

    Full Text Available In recent years, we have developed the multidimensionally-constrained covariant density functional theories (MDC-CDFTs in which both axial and spatial reflection symmetries are broken and all shape degrees of freedom described by βλμ with even μ, such as β20, β22, β30, β32, β40, etc., are included self-consistently. The MDC-CDFTs have been applied to the investigation of potential energy surfaces and fission barriers of actinide nuclei, third minima in potential energy surfaces of light actinides, shapes and potential energy surfaces of superheavy nuclei, octupole correlations between multiple chiral doublet bands in 78Br, octupole correlations in Ba isotopes, the Y32 correlations in N = 150 isotones and Zr isotopes, the spontaneous fission of Fm isotopes, and shapes of hypernuclei. In this contribution we present the formalism of MDC-CDFTs and the application of these theories to the study of fission barriers and potential energy surfaces of actinide nuclei.

  20. Fission hindrance and nuclear viscosity

    Indian Academy of Sciences (India)

    of fission in terms of the ratio of transition states at the saddle point to the level density ... It was also intended to probe any turning over or reduction of γ .... 4. Summary and discussion. In this contribution we have reviewed our measurements which were carried out to inves- tigate the dependence of nuclear viscosity ...

  1. Spin determination of fission resonances

    International Nuclear Information System (INIS)

    Keyworth, G.A.

    1976-01-01

    The present status of available information on the channel quantum numbers for resonance fission and the most urgently needed additional experiments are examined. The role of spin in the 235 U + n system is emphasized. The discussion relies heavily on recent alignment measurements and polarization results

  2. Fission approach to cluster radioactivity

    Indian Academy of Sciences (India)

    2015-08-04

    Aug 4, 2015 ... Also, the analytical superasymmetric fission (ASAF) model is successfully employed to make a systematic search and to predict, with other models, cluster ... those of the staff, the journals, various programmes, and Current Science, has changed from 'ias.ernet.in' (or 'academy.ias.ernet.in') to 'ias.ac.in'. Thus ...

  3. Nuclear fission with inertial confinement

    CERN Document Server

    Koshkarev, D G

    2002-01-01

    The possibility of initiating the explosive fission reaction in a small quantity of fissile material through the heavy ions beam from the powerful accelerator-driver, developed for realization of the thermonuclear synthesis in the deuterium-tritium cylindrical targets with the direct ignition, is considered. The consequences of applying this method in the nuclear engineering are discussed

  4. Anisotropy in the ternary cold fission

    CERN Document Server

    Delion, D S; Greiner, W

    2003-01-01

    We describe the spontaneous ternary cold fission of sup 2 sup 5 sup 2 Cf, accompanied by sup 4 He, sup 1 sup 0 Be and sup 1 sup 4 C within a stationary scattering formalism. We show that the light cluster should be born in the neck region. It decays from the first resonant eigenstate in the Coulomb plus harmonic oscillator potential, centred in this region and eccentric with respect to the symmetry axis. This description gives a simple answer to the question why the averaged values in the energy spectra of emitted clusters are close to each other, in spite of different Coulomb barriers. We have shown that the angular distribution of the emitted light particle is strongly connected with its deformation and the equatorial distance. Experimental angular distributions can be explained by the spherical shapes of emitted clusters, except for a deformed sup 1 sup 0 Be. We also predicted some dependences of half-lives for such tri-nuclear systems upon potential parameters.

  5. LEUbased Fission Mo-99 Process with Reduced Solid Wastes

    International Nuclear Information System (INIS)

    Lee, Seungkon; Lee, Suseung; Jung, Sunghee; Hong, Soonbog; Jang, Kyungduk; Choi, Sang Mu; Lee, Jun Sig; Lim, Incheol

    2014-01-01

    99m Tc emits 140 keV of very low gamma-ray radiation energy, as low as conventional diagnostic X-ray, and has short half-life of 6.0058 hours. Therefore, as radioactive tracer, 99m Tc provides high quality diagnostic images but keeps total patient radiation exposure low. Depending on the tagging pharmaceuticals and procedures, 99m Tc can be applied for the diagnostics of various target organs and diseases: brain, myocardium, thyroid, lungs, liver, gallbladder, kidneys, skeleton, blood and tumors. More than 95% of 99 Mo is produced through fission of 235 U worldwide because, 99m o generated from the fission (fission 99 Mo) exhibits very high specific activity (<100 Ci/g). Over 90% of fission 99 Mo producers have been used highly enriched uranium (HEU) targets so far. However, the IAEA recommends the use of low enriched uranium (LEU) to the 99 Mo producers for nonproliferation reason. These days, worldwide 99 Mo supply is not only insufficient but also unstable. Because, most of the main 99 Mo production reactors are about 50 years old and suffered from frequent and unscheduled shutdown. Planned weekly productivity of 2000 Ci fission 99 Mo, in a 6-day reference, will cover 100% domestic demand of Korea, as well as 20% of international market. It is expected to replace 4.3 million USD ($800/Ci) of 99 Mo import for domestic market while exporting 82.8 million USD for world market, annually

  6. Prompt fissionγ-ray characteristics from neutron-induced fission on 239Pu and the time-dependence of prompt-γray emission

    Science.gov (United States)

    Gatera, Angélique; Göök, Alf; Hambsch, Franz-Josef; Moens, André; Oberstedt, Andreas; Oberstedt, Stephan; Sibbens, Goedele; Vanleeuw, David; Vidali, Marzio

    2018-03-01

    Recent years have seen an increased interest in prompt fission γ-ray (PFG) measurements motivated by a high priority request of the OECD/NEA for high precision data, mainly for the nuclear fuel isotopes 235U and 239Pu. Our group has conducted a PFG measurement campaign using state-of-the-art lanthanum halide detectors for all the main actinides to a precision better than 3%. The experiments were performed in a coincidence setup between a fission trigger and γ-ray detectors. The time-of-flight technique was used to discriminate photons, traveling at the speed of light, and prompt fission neutrons. For a full rejection of all neutrons below 20 MeV, the PFG time window should not be wider than a few nanoseconds. This window includes most PFG, provided that no isomeric states were populated during the de-excitation process. When isomeric states are populated, PFGs can still be emitted up to 1 yus after the instant of fission or later. To study these γ-rays, the detector response to neutrons had to be determined and a correction had to be applied to the γ-ray spectra. The latest results for PFG characteristics from the reaction 239Pu(nth,f) will be presented, together with an analysis of PFGs emitted up to 200 ns after fission in the spontaneous fission of 252Cf as well as for thermal-neutron induced fission on 235U and 239Pu. The results are compared with calculations in the framework of the Hauser-Feshbach Monte Carlo code CGMF and FIFRELIN.

  7. Increasing Diversity of Biological Membrane Fission Mechanisms.

    Science.gov (United States)

    Renard, Henri-François; Johannes, Ludger; Morsomme, Pierre

    2018-01-04

    Membrane fission is essential to life. It is required for many fundamental cellular processes, as diverse as cyto- and karyokinesis, organelle division, membrane repair, and membrane trafficking and endocytosis. While membrane fission was originally seen as resulting from the action of mechanoenzymes such as dynamin, it is clear that the reality is more complex. In this review, we propose an updated overview of fission mechanisms, and try to extract essential requirements for each. We also present examples of cellular processes that involve these fission mechanisms. Finally, we list pending questions, whether they are specific to a peculiar fission mechanism or more general to the field. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Heavy-ion induced fission reactions

    International Nuclear Information System (INIS)

    Britt, H.C.; Fowler, M.M.; Fraenkel, Z.; Gavron, A.; Plicht, J.; Wilhelmy, J.B.; Plasil, F.; Awes, T.; Young, G.

    1983-01-01

    Heavy-ion induced fission reactions are investigated. The problem of obtaining a representative set of fission-cross section data, so that it would be possible to test both the mass and angular momentum dependence of fission barriers in the mass region 150 9 Be through 64 Ni. The experimental data clearly show the qualitative effects of angular momentum, excitation energy and fissility on the fission cross section. They provide an ideal testing ground for theoretical models of fission in this mass region

  9. Sequential Detection of Fission Processes for Harbor Defense

    Energy Technology Data Exchange (ETDEWEB)

    Candy, J V; Walston, S E; Chambers, D H

    2015-02-12

    With the large increase in terrorist activities throughout the world, the timely and accurate detection of special nuclear material (SNM) has become an extremely high priority for many countries concerned with national security. The detection of radionuclide contraband based on their γ-ray emissions has been attacked vigorously with some interesting and feasible results; however, the fission process of SNM has not received as much attention due to its inherent complexity and required predictive nature. In this paper, on-line, sequential Bayesian detection and estimation (parameter) techniques to rapidly and reliably detect unknown fissioning sources with high statistical confidence are developed.

  10. Some methods for the detection of fissionable matter

    International Nuclear Information System (INIS)

    Guery, M.

    1967-03-01

    A number of equipments or processes allowing to detect uranium or plutonium in industrial plants, and in particular to measure solution concentrations, are studied here. Each method has its own field of applications and has its own performances, which we have tried to define by calculations and by experiments. The following topics have been treated: γ absorptiometer with an Am source, detection test by neutron multiplication, apparatus for the measurement of the α activity of a solution, fissionable matter detection by γ emission, fissionable matter detection by neutron emission. (author) [fr

  11. Preclinical study of selective thermal neutron capture treatment of pigs having spontaneous melanoma using melanin productive activity

    International Nuclear Information System (INIS)

    Miyashita, Ichiro; Sawaya, Hiroshi; Nomura, Toyoichiro

    1980-01-01

    Four pigs having spontaneous melanoma were irradiated with 0.5 - 2 x 10 13 n/cm 2 of thermal neutron under remote anesthesia. Compounds of 10 B used in this experiment were 10 B 12 -chlorpromazine ( 10 B 12 -CPZ), 10 B-dopa, and 10 B 1 -para-boronophenylalanine ( 10 B 1 -BPA), and they were injected into melanoma or regions around melanoma. After irradiation of thermal neutron, melanoma tended to reduce in four pigs, and melanoma cells in white fur and hair bulb disappeared in 3 of 4 pigs. Hematological examinations and blood chemistry tests did not show any changes in blood findings both before and after the irradiation, and white blood cell counts were within a normal range. Dermatitis following the irradiation disappeared one week later. Histological changes one month after the irradiation indicated that many melanophages feeding melanosome replaced melanoma cells, which suggested disintegration of melanoma cells. Marked effectiveness of this treatment was recognized in each pig. 10 B-BPA.HCI was injected into one pig twice, and its accumulation in melanoma and normal regions around melanoma was expressed as boron concentrations. As a result, the accumulation in melanoma (6.6 μg/g wet tissue) was 3.1 times as much as that in normal regions around melanoma (2.1 μg/g wet tissue). (Tsunoda, M.)

  12. Altered spontaneous brain activity pattern in patients with high myopia using amplitude of low-frequency fluctuation: a resting-state fMRI study

    Directory of Open Access Journals (Sweden)

    Huang X

    2016-11-01

    Full Text Available Xin Huang,1,2,* Fu-Qing Zhou,3,* Yu-Xiang Hu,1 Xiao-Xuan Xu,1 Xiong Zhou,4 Yu-Lin Zhong,1 Jun Wang,4 Xiao-Rong Wu1 1Department of Ophthalmology, The First Affiliated Hospital of Nanchang University, Nanchang, 2Department of Ophthalmology, The First People’s Hospital of Jiujiang City, Jiujiang, 3Department of Radiology, The First Affiliated Hospital of Nanchang University, Jiangxi Province Medical Imaging Research Institute, 4Second Department of Respiratory Disease, Jiangxi Provincial People’s Hospital, Nanchang, Jiangxi, People’s Republic of China *These authors contributed equally to this work Objective: Many previous reports have demonstrated significant neural anatomy changes in the brain of high myopic (HM patients, whereas the spontaneous brain activity changes in the HM patients at rest are not well studied. Our objective was to use amplitude of low-frequency fluctuation (ALFF method to investigate the changes in spontaneous brain activity in HM patients and their relationships with clinical features. Methods: A total of 38 patients with HM (17 males and 21 females and 38 healthy controls (HCs (17 males and 21 females closely matched in age, sex, and education underwent resting-state functional magnetic resonance imaging scans. The ALFF method was used to assess local features of spontaneous brain activity. The relationship between the mean ALFF signal values in many brain regions and the clinical features in HM patients was calculated by correlation analysis. Results: Compared with HCs, the HM patients had significantly lower ALFF in the right inferior and middle temporal gyrus, left middle temporal gyrus, left inferior frontal gyrus/putamen, right inferior frontal gyrus/putamen/insula, right middle frontal gyrus, and right inferior parietal lobule and higher ALFF values in the bilateral midcingulate cortex, left postcentral gyrus, and left precuneus/inferior parietal lobule. However, no relationship was found between the mean ALFF

  13. Disturbed spontaneous brain activity pattern in patients with primary angle-closure glaucoma using amplitude of low-frequency fluctuation: a fMRI study

    Directory of Open Access Journals (Sweden)

    Huang X

    2015-07-01

    Full Text Available Xin Huang,1,* Yu-Lin Zhong,1,* Xian-Jun Zeng,2 Fuqing Zhou,2 Xin-Hua Liu,1 Pei-Hong Hu,1 Chong-Gang Pei,1 Yi Shao,1 Xi-Jian Dai21Department of Ophthalmology, 2Department of Radiology, The First Affiliated Hospital of Nanchang University, Nangchang, Jiangxi, People’s Republic of China*These authors contributed equally to this workObjective: The aim of this study is to use amplitude of low-frequency fluctuation (ALFF as a method to explore the local features of spontaneous brain activity in patients with primary angle -closure glaucoma (PACG and ALFFs relationship with the behavioral performances.Methods: A total of twenty one patients with PACG (eight males and 13 females, and twenty one healthy subjects (nine males and twelve females closely matched in age, sex, and education, each underwent a resting-state functional magnetic resonance imaging scan. The ALFF method was used to assess the local features of spontaneous brain activity. The correlation analysis was used to explore the relationships between the observed mean ALFF signal values of the different areas in PACG patients and the thickness of the retinal nerve fiber layer (RNFL. Results: Compared with the healthy subjects, patients with PACG had significant lower ALFF areas in the left precentral gyrus, bilateral middle frontal gyrus, bilateral superior frontal gyrus, right precuneus, and right angular gyrus, and higher areas in the right precentral gyrus. In the PACG group, there were significant negative correlations between the mean ALFF signal value of the right middle frontal gyrus and the left mean RNFL thickness (r=-0.487, P=0.033, and between the mean ALFF signal value of the left middle frontal gyrus and the right mean RNFL thickness (r=-0.504, P=0.020. Conclusion: PACG mainly involved in the dysfunction in the frontal lobe, which may reflect the underlying pathologic mechanism of PACG.Keywords: angle-closure glaucoma, amplitude of low-frequency fluctuation, functional

  14. Blockade of persistent sodium currents contributes to the riluzole-induced inhibition of spontaneous activity and oscillations in injured DRG neurons.

    Directory of Open Access Journals (Sweden)

    Rou-Gang Xie

    Full Text Available In addition to a fast activating and immediately inactivating inward sodium current, many types of excitable cells possess a noninactivating or slowly inactivating component: the persistent sodium current (I(NaP. The I(NaP is found in normal primary sensory neurons where it is mediated by tetrodotoxin-sensitive sodium channels. The dorsal root ganglion (DRG is the gateway for ectopic impulses that originate in pathological pain signals from the periphery. However, the role of I(NaP in DRG neurons remains unclear, particularly in neuropathic pain states. Using in vivo recordings from single medium- and large-diameter fibers isolated from the compressed DRG in Sprague-Dawley rats, we show that local application of riluzole, which blocks the I(NaP, also inhibits the spontaneous activity of A-type DRG neurons in a dose-dependent manner. Significantly, riluzole also abolished subthreshold membrane potential oscillations (SMPOs, although DRG neurons still responded to intracellular current injection with a single full-sized spike. In addition, the I(NaP was enhanced in medium- and large-sized neurons of the compressed DRG, while bath-applied riluzole significantly inhibited the I(NaP without affecting the transient sodium current (I(NaT. Taken together, these results demonstrate for the first time that the I(NaP blocker riluzole selectively inhibits I(NaP and thereby blocks SMPOs and the ectopic spontaneous activity of injured A-type DRG neurons. This suggests that the I(NaP of DRG neurons is a potential target for treating neuropathic pain at the peripheral level.

  15. Fission dynamics in the proton induced fission of heavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Rubchenya, V.A. E-mail: rubchen@phys.jyu.fi; Trzaska, W.H.; Itkis, I.M.; Itkis, M.G.; Kliman, J.; Kniajeva, G.N.; Kondratiev, N.A.; Kozulin, E.M.; Krupa, L.; Pokrovski, I.V.; Voskressenski, V.M.; Hanappe, F.; Materna, T.; Dorvaux, O.; Stuttge, L.; Chubarian, G.; Khlebnikov, S.V.; Vakhtin, D.N.; Lyapin, V.G

    2004-04-05

    Multi-parameter correlation study of the reaction {sup 242}Pu(p, f) at E{sub p} 13, 20 and 55 MeV has been carried out. Fission fragment mass and kinetic energy distributions and the double differential neutron spectra have been measured. It was observed that the two-humped shape of mass distributions prevailed up to highest proton energy. Manifestation of the nuclear shell Z 28 near fragment mass A{sub fr} = 70 has been detected. The experimental results were analyzed in the framework of a time-dependent statistical model with inclusion of nuclear friction effects in the fission process. The multi-parameter correlation study of the reaction.

  16. A fission fragment detector for correlated fission output studies

    Energy Technology Data Exchange (ETDEWEB)

    Mosby, S., E-mail: smosby@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Tovesson, F.; Couture, A. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Duke, D.L. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Colorado School of Mines, Golden, CO 80401 (United States); Kleinrath, V. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Idaho State University, Pocatello, ID 83201 (United States); Meharchand, R.; Meierbachtol, K.; O' Donnell, J.M.; Perdue, B.; Richman, D. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Shields, D. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Colorado School of Mines, Golden, CO 80401 (United States)

    2014-09-01

    A digital data acquisition system has been combined with a double Frisch gridded ionization chamber for use at both moderated and unmoderated neutron sources at the Los Alamos Neutron Science (LANSCE) facility. The high efficiency of the instrument combined with intense LANSCE beams and new acquisition system permits fission output measurements across 11 orders of magnitude incident neutron energy. The acquisition and analysis system is presented along with the first in-beam performance tests of the setup.

  17. Spontaneous pneumothorax in weightlifters.

    Science.gov (United States)

    Marnejon, T; Sarac, S; Cropp, A J

    1995-06-01

    Spontaneous pneumothorax is infrequently caused by strenuous exertion. To our knowledge there has only been one case of spontaneous pneumothorax associated with weightlifting reported in the medical literature. We describe three consecutive cases of spontaneous pneumothorax associated with weightlifting. We postulate that spontaneous pneumothorax in these patients may be secondary to improper breathing techniques. It is important that physicians and weight trainers be aware of the association between weight lifting and spontaneous pneumothorax and assure that proper instruction is given to athletes who work with weights.

  18. Progress in fission product nuclear data. Issue no. 6

    International Nuclear Information System (INIS)

    Lammer, G.; Lammer, M.

    1980-06-01

    This is the sixth issue of a report series on Fission Product Nuclear Data (FPND) which is published by the Nuclear Data Section (NDS) of the International Atomic Energy Agency (IAEA). The purpose of this series is to inform scientists working on FPND, or using such data, about all activities in this field which are planned, ongoing, or have recently been completed

  19. MCNP6. Simulating Correlated Data in Fission Events

    Energy Technology Data Exchange (ETDEWEB)

    Rising, Michael Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sood, Avneet [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-12-03

    This report is a series of slides discussing the MCNP6 code and its status in simulating fission. Applications of interest include global security and nuclear nonproliferation, detection of special nuclear material (SNM), passive and active interrogation techniques, and coincident neutron and photon leakage.

  20. Fission products analysis. Strontium 89 and strontium 90 radiometric determination

    International Nuclear Information System (INIS)

    Anon.

    Determination of strontium 89 et 90 in nitric solutions of fission products, suitable for strontium content giving a nuclear activity of at least 10 -5 microcurie/ml. Calcium, barium, yttrium and rare earths are eliminated before beta counting with and without threshold [fr