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Sample records for cascade intranuclear gamma

  1. Intranuclear cascade models lack dynamic flow

    OpenAIRE

    Molitoris, Joseph J.; Stöcker, Horst; Gustafsson, Hans-Ake; Cugnon, Joseph; L'Hote, Denis

    2006-01-01

    We study the recent claim that the intranuclear cascade model exhibits collective sidewards flow. 4000 intranuclear cascade simulations of the reaction Nb(400 MeV/nucleon)+Nb are performed employing bound and unbound versions of the Cugnon cascade. We show that instability of the target and projectile nuclei in the unbound cascade produces substantial spurious sidewards flow angles, for spectators as well as for participants. Once the nuclear binding is included, the peak of the flow angle di...

  2. Intranuclear cascade description of relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    A microscopic theory of heavy ion reactions based on the intranuclear cascade model is briefly discussed in an attempt to study the compression of nuclear matter. Double differential cross sections of 20Ne + 238U are shown as functions of impact parameter and bombarding energy for energies between 100 and 900 MeV/nucleon

  3. Fragmentation calculation by intranuclear-cascade-evaporation code

    Energy Technology Data Exchange (ETDEWEB)

    Shigyo, Nobuhiro; Iga, Kiminori; Ishibashi, Kenji [Kyushu Univ., Fukuoka (Japan)

    1997-03-01

    High Energy Transport Code (HETC) based on the intranuclear-cascade-evaporation model is modified for calculating the fragmentation cross section. For the intranuclear-cascade process, nucleon-nucleon cross sections are used for collision computation; effective in-medium-corrected cross sections are adopted instead of the original free-nucleon collision. The exciton model is adopted for improvement of backward nucleon-emission cross section for low-energy nucleon-incident events. The fragmentation reaction is incorporated into the original HETC as a subroutine set by the use of the systematics of the reaction. The modified HETC (HETC-3STEP/FRG) reproduces experimental fragment yields to a reasonable degree. (author)

  4. Relativistic nuclear reactions and the intranuclear cascade method

    International Nuclear Information System (INIS)

    The intranuclear cascade (INC) procedure is analised as a method to describe the processes of relativistic heavy ions collisions. The effects caused by nucleon concentration during the collision are discussed. It is shown explicitly that the occurence of nonbinary collisions among particles is not at all negligible, in spite of the fact that the convencional INC only permits nucleon-nucleon binary collisions. The relativistic invariance of the results obtained by the INC method is discussed. This is especially important when the method is applied for much higher energies. Many of conventional procedures in the method will give certainly different predictions depending on what system of reference is used. The origin of such non-invariance nature of INC calculations is discussed and an alternative way of defining the INC procedure which presents a better credibility with respect to the relativistic invariance property is proposed. (Author)

  5. On the influence of the mean-free-path parameter on intranuclear cascade calculations

    International Nuclear Information System (INIS)

    It is shown that, contrary to a recent contention by Ginocchio and Blann, intranuclear cascade model calculations do not demonstrate the inadmissibility of a nucleon mean free path in nuclear matter longer than that evaluated from free nucleon-nucleon scattering cross sections

  6. Cluster approach to intranuclear cascade for relativistic heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Kodama, T.; Duarte, S.B.; Chung, K.C.; Nazareth, R.A.M.S.

    1982-08-23

    A new approach to the intranuclear cascade model for relativistic heavy-ion reactions is presented. The effect of nucleon concentration on the collision process is explicitly included. It is found that the contributions from the nonbinary processes are far from being negligible. Such processes are shown to broaden the angular distribution of inclusive proton spectra for /sup 20/Ne+/sup 238/U head-on collisions.

  7. $K^{+}$ momentum spectrum from $(K^{-},K^{+})$ reactions in intranuclear cascade model

    CERN Document Server

    Nara, Y; Harada, T; Engel, A

    1996-01-01

    In a framework of intranuclear cascade (INC) type calculation, we study a momentum spectrum in reactions \\KK at a beam momentum of 1.65 GeV/c. INC model calculations are compared with the relativistic impulse approximation (RIA) calculations to perform the detailed study of the reaction mechanism. We find that the INC model can reproduce the experimental data on various targets. Especially, in the low-momentum region, the forward-angle cross sections of the $(K^-,K^+)$ reaction on from light to heavy targets are consistently explained with the two-step strangeness exchange and production processes with various intermediate mesons, and $\\phi$, $a_0$ and $f_0$ productions and their decay into $K^+K^-$. In the two-step processes, inclusion of meson and hyperon resonances is found to be essential.

  8. Processes involving few degrees of freedom in the frame of Intranuclear Cascade approaches

    Science.gov (United States)

    Cugnon, J.; Boudard, A.; David, J.-C.; Leray, S.; Mancusi, D.

    2016-05-01

    This article focuses on spallation reactions, i.e. interactions of energetic nucleons, basically with a kinetic energy in the 100MeV to a few GeV range, with a target nucleus. These processes are described rather successfully by the so-called Intranuclear Cascade (INC) plus evaporation models. They can be viewed as a first stage of nucleon-nucleon collisions, ejecting fast particles, followed by evaporation of slow particles from the target remnant. These cascade + evaporation models have, now, globally reached a high level of predictive power, owing in particular to successive research programs. The present work, which is an outcome of one of these programs, the recent European Union ANDES research program, deals with a set of reactions (or observable quantities), which can be due to a single collision, such as the one-nucleon removal reactions or the quasi-elastic elastic process. A survey of the experimental data is presented, which allows to clearly point out that, often, the INC models are unsatisfactory for the description of these peculiar events, whereas they are rather successful for the rest of the experimental data. This paradoxical situation is tentatively related to quasi-particle effects which are neglected in INC models.

  9. Intranuclear cascade calculation of high-energy heavy-ion interactions

    International Nuclear Information System (INIS)

    We have extended the intranuclear cascade model of Chen et al. to high-energy reactions between two heavy ions. The results of the calculations are compared with experimental results for the inclusive proton and pion cross sections, two-particle correlations, particle multiplicity distributions, and spallation cross section distributions from light (12C + 12C) to heavy (40Ar + 238U) projectile-target systems in the laboratory bombarding energy range E/A = 250--1000 MeV. The comparison shows that the model is fairly successful in reproducing the various aspects of high-energy reactions between heavy ions. The discrepancies between the calculations and the experimental results are probably due to shortcomings of the present calculation, particularly the neglect of interactions between cascade particles, and do not provide strong evidence for cooperative phenomena in high-energy heavy-ion reactions. We also show that the assumption that high particle multiplicities are indicative of central (small impact parameter) collisions is well founded for heavy projectile-target systems

  10. The performance of a new Geant4 Bertini intra-nuclear cascade model in high throughput computing (HTC) cluster architecture

    International Nuclear Information System (INIS)

    We study the performance of a new Bertini intra-nuclear cascade model implemented in the general detector simulation tool-kit Geant4 with a High Throughput Computing (HTC) cluster architecture. A 60 node Pentium III open-Mosix cluster is used with the Mosix kernel performing automatic process load-balancing across several CPUs. The Mosix cluster consists of several computer classes equipped with Windows NT workstations that automatically boot, daily and become nodes of the Mosix cluster. The models included in our study are a Bertini intra-nuclear cascade model with excitons, consisting of a pre-equilibrium model, a nucleus explosion model, a fission model and an evaporation model. The speed and accuracy obtained for these models is presented. (authors)

  11. The performance of a new Geant4 Bertini intra-nuclear cascade model in high throughput computing (HTC) cluster architecture

    Energy Technology Data Exchange (ETDEWEB)

    Aatos, Heikkinen; Andi, Hektor; Veikko, Karimaki; Tomas, Linden [Helsinki Univ., Institute of Physics (Finland)

    2003-07-01

    We study the performance of a new Bertini intra-nuclear cascade model implemented in the general detector simulation tool-kit Geant4 with a High Throughput Computing (HTC) cluster architecture. A 60 node Pentium III open-Mosix cluster is used with the Mosix kernel performing automatic process load-balancing across several CPUs. The Mosix cluster consists of several computer classes equipped with Windows NT workstations that automatically boot, daily and become nodes of the Mosix cluster. The models included in our study are a Bertini intra-nuclear cascade model with excitons, consisting of a pre-equilibrium model, a nucleus explosion model, a fission model and an evaporation model. The speed and accuracy obtained for these models is presented. (authors)

  12. Intranuclear-cascade-evaporation model for inelastic nuclear collisions and its application in biomedical and MFE research

    International Nuclear Information System (INIS)

    A brief description of the intranuclear cascade evaporation model is given and comparisons between results obtained with this model and experimental cross section data are presented. Also transport calculations carried out using differential cross section data obtained with the studied model are presented and compared with experimental data. These comparisons are, it is expected, sufficient to indicate that the model is not completely unreliable in the energy region of interest below 50 MeV and to indicate that transport calculations of interest in biomedical and magnetic fusion energy applications can at present be carried out. 26 references

  13. Cross sections of proton- and neutron-induced reactions by the Liège intranuclear cascade model

    Science.gov (United States)

    Chen, Jian; Dong, Tiekuang; Ren, Zhongzhou

    2016-06-01

    The purpose of the paper is mainly to test the validity of the Liège intranuclear cascade (INCL) model in calculating the cross sections of proton-induced reactions for cosmogenic nuclei using the newly compiled database of proton cross sections. The model calculations of 3He display the rising tendency of cross sections with the increase of energy, in accordance with the experimental data. Meanwhile, the differences between the theoretical results and experimental data of production cross sections (10Be and 26Al) are generally within a factor of 3, meaning that the INCL model works quite well for the proton-induced reactions. Based on the good agreement, we predict the production cross sections of 26Al from reactions n + 27Al, n + 28Si, and n + 40Ca and those of 10Be from reactions n + 16O and n + 28Si. The results also show a good agreement with a posteriori excitation functions.

  14. Inclusion of correlations in the empirical selection of intranuclear cascade nucleons from high-energy hadron-nucleus collisions

    International Nuclear Information System (INIS)

    The very high energy (5 GeV to 20 TeV) hadron-nucleus differential particle production model found in the Monte Carlo transport code FLUKA87 has been adapted for inclusion in the transport code HETC88. The empirical selection of intranuclear cascade nucleons has been modified to provide simple correlations with the randomly selected number of hadron-nucleon collisions. A standard method of calculating the excitation energy of the compound nucleus preceding an added evaporation step by assuming the particles are produced in a one-dimensional nuclear well is applied. This method, coupled with the above correlations, leads to improved correlations of the excitation energy with the A and Z of the compound nucleus, and then to greatly improved distributions of the residual nuclei following evaporation. The frequency distributions of low energy (β < .7) charged particles show good agreement with experiment for 200 GeV protons incident on emulsions. Average multiplicities of shower and grey particles after evaporation for protons and pions incident on several elements are also compared with experiment. 23 refs., 10 figs., 1 tab

  15. Cascaded Gamma Rays as a Probe of Cosmic Rays

    Science.gov (United States)

    Murase, Kohta

    2014-06-01

    Very-high-energy (VHE) and ultra-high-energy (UHE) gamma rays from extragalactic sources experience electromagnetic cascades during their propagation in intergalactic space. Recent gamma-ray data on TeV blazars and the diffuse gamma-ray background may have hints of the cascade emission, which are especially interesting if it comes from UHE cosmic rays. I show that cosmic-ray-induced cascades can be discriminated from gamma-ray-induced cascades with detailed gamma-ray spectra. I also discuss roles of structured magnetic fields, which suppress inverse-Compton pair halos/echoes but lead to guaranteed signals - synchrotron pair halos/echoes.

  16. Intranuclear cascade model for 50-MeV-region (p, p'x) reactions over a wide target mass range

    International Nuclear Information System (INIS)

    In our previous study, the applicable range of the intranuclear cascade model was successfully extended to lower incident energy (p, p'x) reactions by introducing trajectory deflections and low-energy-loss process due to collective excitations. However, the model's validity was confirmed only for a 56Fe target. In the present work we widen the applicable range of masses of the target nucleus. First, we derive an expression for the response function, which gives the probability of collective excitation strengths, to fit the distorted-wave Born approximation results as a function of the target mass number and the beam energy. Second, the barrier transmission coefficient was investigated. An expression with a modified Gamow penetration factor was chosen from four phenomenological forms of one-dimensional barrier transmission coefficients. Calculations with the proposed model followed by a generalized evaporation model were carried out for double-differential cross sections of (p, p'x) reactions at 30–60 MeV. Although the response function and the transmission coefficient were only parameterized approximately, the proposed model showed good agreements with experimental observations for a variety of nuclear targets from 12C to 209Bi. (author)

  17. The Liege Intranuclear Cascade model - Towards a unified description of nuclear reactions induced by nucleons and light ions from a few MeV to a few GeV

    International Nuclear Information System (INIS)

    Spallation reactions are usually defined as the reactions induced by hadrons and/or light ions with an incident energy comprised between, say 100 MeV to 2 GeV (per nucleon for incident light ions). They are characterized by a copious emission of neutrons, accompanied by a lesser rate emission of light charged particles. The predictive power of the last version INCL4.6 of the Liege Intranuclear Cascade model for spallation is reviewed. The last version was published in 2013. The main new development involves the treatment of cluster-induced reactions. The incident cluster is viewed as a collection of off-shell nucleons - their energy is reduced by an average potential energy - in order to have correct energy and momentum of the projectile. The projectile nucleons are divided into geometrical spectators (those which do not intercept the target) and participants. The former are put on shell as free nucleons or bound to clusters. The latter are making a compound nucleus or are initiating in common a usual cascade process, according as their available energy is low or high. The good results obtained both at low and high energy extend the domain of validity of the model and allow the description of spallation reactions, except the coherent processes, by a unique model from a few MeV to a few GeV incident energy

  18. Electromagnetic cascade masquerade: a way to mimic $\\gamma$--ALP mixing effects in blazar spectra

    CERN Document Server

    Dzhatdoev, T A; Kircheva, A P; Lyukshin, A A

    2016-01-01

    Most of the studies on extragalactic {\\gamma}-ray propagation performed up to now only accounted for primary gamma-ray absorption and adiabatic losses (absorption-only model). However, there is growing evidence that this model is oversimplified and must be modified in some way. (...) There are many hints that a secondary component from electromagnetic cascades initiated by primary $\\gamma$-rays or nuclei may be observed in the spectra of some blazars. We study the impact of electromagnetic cascades from primary $\\gamma$-rays or protons on the physical interpretation of blazar spectra obtained with imaging Cherenkov telescopes. We use the publicly-available code ELMAG to compute observable spectra of electromagnetic cascades from primary $\\gamma$-rays. For the case of primary proton, we develop a simple, fast, and reasonably accurate hybrid method to calculate the observable spectrum. (...) Electromagnetic cascades show at least two very distinct regimes labeled by the energy of the primary $\\gamma$-ray ($E_{0...

  19. Treatment of the electrons-photons cascade in the high energy gamma transport; Traitement de la cascade electrons - photons dans le transport des gammas de haute energie

    Energy Technology Data Exchange (ETDEWEB)

    Riz, D

    1999-10-01

    The electrons-photons cascade is an important phenomena occurring in gamma transport. This phenomena called also Bremsstrahlung happens whenever electrons, produced in a photon-atom interaction, trigger emission of photons while slowing down in the matter. Some previous calculations have shown that in particular circumstances, a flux of photons going through a lead plate can be multiplied by 3 when Bremsstrahlung is taken into account. This work is dedicated to a new method developed in CEA to take into account Bremsstrahlung in any gamma transport code using multigroup constants. An electron or a positron produced by an incident photon {gamma} will move till it has lost all its energy in collisions or in emissions of Bremsstrahlung {gamma}'. The path of the electron is short so all the Bremsstrahlung {gamma}' are assumed to be produced at the point of creation of the electron or positron. The result of this method is the knowledge of a transfer probability {gamma}{yields}{gamma}' that can be used in classical gamma transport codes. (A.C.)

  20. Semi-Analytic Model for Intergalactic Gamma-Ray Cascades in Extragalactic Magnetic Fields

    CERN Document Server

    Huan, H

    2011-01-01

    Primary gamma rays emitted by extragalactic sources, such as blazars, will generate electromagnetic cascades in intergalactic space. These cascades proceed via electron-positron pair production and inverse Compton scattering on cosmic background radiation, mainly the cosmic microwave background (CMB) and extragalactic background light (EBL) fields. The existence of an extragalactic magnetic field (EGMF) could deflect electron-positron pair trajectories and scatter the cascade photons, possibly creating a halo around the source while suppressing the cascade flux collected by a detector. We develop a semi-analytic model for the cascade process and apply it to combine GeV-TeV data on high-frequency-peaked Bl Lacertae objects (HBLs) from the Fermi Large Area Telescope (LAT) and ground-based Cherenkov telescopes, comparing observation results with model predictions using a robust statistical framework. Lower limits with different confidence levels on the field strength of the EGMF derived from this procedure are d...

  1. Monte Carlo Modeling of Cascade Gamma Rays in 86Y PET imaging: Preliminary results

    OpenAIRE

    Zhu, Xuping; El Fakhri, Georges

    2009-01-01

    86Y is a PET agent that could be used as an ideal surrogate to allow personalized dosimetry in 90Y radionuclide therapy. However, 86Y also emits cascade gamma rays. We have developed a Monte Carlo program based on SimSET to model cascade gamma rays in PET imaging. The new simulation was validated with the GATE simulation package. Agreements within 15% were found in spatial resolution, apparent scatter fraction (ratio of coincidences outside peak regions in line source sinograms), singles and ...

  2. U-238 neutron-capture gamma-cascade generation and transport simulation for capture-tank response (final report). Doctoral thesis

    Energy Technology Data Exchange (ETDEWEB)

    Rosener, T.J.

    1992-05-07

    A computer analysis has been performed to evaluate the energy dependent response of a capture tank to the gamma rays emitted in the cascades of the excited U-239 nucleus. This model determines the energies of the gamma-ray cascades, the order of emission of the gamma rays in a cascade, and the gamma-ray multiplicity of the cascades using Monte Carlo techniques. A capture tank responds to the combined effect of the various gamma rays emitted in the cascade. Examined is the energy deposition in a capture tank by the cascades generated in resonant (surface) capture and off-resonant (volumetric) capture, with and without internal conversion. Off-resonant capture deposits, on the average, less energy than resonant capture, due to self-shielding of the gamma-rays in the capture sample. Internal conversion has negligible effect on the average cascade energy deposited in the capture tank. Gamma-ray cascade, Capture tank, U-238 neutron capture.

  3. Monte Carlo Modeling of Cascade Gamma Rays in 86Y PET imaging: Preliminary results

    Science.gov (United States)

    Zhu, Xuping; El Fakhri, Georges

    2011-01-01

    86Y is a PET agent that could be used as an ideal surrogate to allow personalized dosimetry in 90Y radionuclide therapy. However, 86Y also emits cascade gamma rays. We have developed a Monte Carlo program based on SimSET to model cascade gamma rays in PET imaging. The new simulation was validated with the GATE simulation package. Agreements within 15% were found in spatial resolution, apparent scatter fraction (ratio of coincidences outside peak regions in line source sinograms), singles and coincidences statistics and detected photons energy distribution within the PET energy window. A 20% discrepancy was observed in the absolute scatter fraction, likely caused by differences in the tracking of higher-energy cascade gamma photons. On average the new simulation is 6 times faster than GATE, and the computing time can be further improved by using variance reduction techniques currently available in SimSET. Comparison with phantom acquisitions showed agreements in spatial resolutions and the general shape of projection profiles; however, the standard scatter correction method on the scanner is not directly applicable for 86Y PET as it leads to incorrect scatter fractions. The new simulation was used to characterize 86Y PET. Compared with conventional 18F PET, in which major contamination at low count rates comes from scattered events, cascade gamma-involved events are more important in 86Y PET. The two types of contaminations have completely different distribution patterns, which should be considered for the corrections of their effects. Our approach will be further improved in the future in the modeling of random coincidences and tracking of high energy photons, and simulation results will be used for the development of correction methods in 86Y PET. PMID:19521011

  4. Monte Carlo modeling of cascade gamma rays in {sup 86}Y PET imaging: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Xuping; El Fakhri, Georges [Radiology Department, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts, MA (United States)], E-mail: xzhu4@Partners.org, E-mail: elfakhri@pet.mgh.harvard.edu

    2009-07-07

    {sup 86}Y is a PET agent that could be used as an ideal surrogate to allow personalized dosimetry in {sup 90}Y radionuclide therapy. However, {sup 86}Y also emits cascade gamma rays. We have developed a Monte Carlo program based on SimSET (Simulation System for Emission Tomography) to model cascade gamma rays in PET imaging. The new simulation was validated with the GATE simulation package. Agreements within 15% were found in spatial resolution, apparent scatter fraction (ratio of coincidences outside peak regions in line source sinograms), single and coincidence statistics and detected photons energy distribution within the PET energy window. A discrepancy of 20% was observed in the absolute scatter fraction, likely caused by differences in the tracking of higher energy cascade gamma photons. On average, the new simulation is 6 times faster than GATE, and the computing time can be further improved by using variance reduction techniques currently available in SimSET. Comparison with phantom acquisitions showed agreements in spatial resolutions and the general shape of projection profiles; however, the standard scatter correction method on the scanner is not directly applicable to {sup 86}Y PET as it leads to incorrect scatter fractions. The new simulation was used to characterize {sup 86}Y PET. Compared with conventional {sup 18}F PET, in which major contamination at low count rates comes from scattered events, cascade gamma-involved events are more important in {sup 86}Y PET. The two types of contaminations have completely different distribution patterns, which should be considered for the corrections of their effects. Our approach will be further improved in the future in the modeling of random coincidences and tracking of high-energy photons, and simulation results will be used for the development of correction methods in {sup 86}Y PET.

  5. New possibilities for improving the accuracy of parameter calculations for cascade gamma-ray decay of heavy nuclei

    CERN Document Server

    Sukhovoj, A M; Khitrov, V A

    2001-01-01

    The level density and radiative strength functions which accurately reproduce the experimental intensity of two- step cascades after thermal neutron capture and the total radiative widths of the compound states were applied to calculate the total gamma-ray spectra from the (n,gamma) reaction. In some cases, analysis showed far better agreement with experiment and gave insight into possible ways in which these parameters need to be corrected for further improvement of calculation accuracy for the cascade gamma-decay of heavy nuclei.

  6. Reanalysis of the process of the cascade gamma decay of compound state of $^{198}$Au

    CERN Document Server

    Sukhovoj, A M; Crawford, B E; Stephenson, S L

    2008-01-01

    To further study the "pygmy" resonance phenomena in the photon strength function, we reanalyzed the two-step cascade data for the target nucleus $^{197}$Au using the Dubna group approach. The range of obtained values allows for meaningful conclusions: the level density at low excitation energy shows a step-like behavior; the electric dipole photon strength function has a broad maximum around $E_{\\gamma}=5$ MeV and is not typical of a "pygmy" resonance; the level density below $B_{n}$ also demonstrates step-like behavior.

  7. Constraining Very Heavy Dark Matter Using Diffuse Backgrounds of Neutrinos and Cascaded Gamma Rays

    CERN Document Server

    Murase, Kohta

    2012-01-01

    We consider multi-messenger constraints on very heavy dark matter (VHDM) from recent Fermi gamma-ray and IceCube neutrino observations of isotropic background radiation. Fermi data on the diffuse gamma-ray background (DGB) shows a possible unexplained feature at very high energies (VHE), which we have called the VHE Excess relative to expectations for an attenuated power law extrapolated from lower energies. We show that VHDM could explain this excess, and that neutrino observations will be an important tool for testing this scenario. More conservatively, we derive new constraints on the properties of VHDM for masses of 10^3-10^10 GeV. These generic bounds follow from cosmic energy budget constraints for gamma rays and neutrinos that we developed elsewhere, based on detailed calculations of cosmic electromagnetic cascades and also neutrino detection rates. We show that combining both gamma-ray and neutrino data is essential for making the constraints on VHDM properties both strong and robust. In the lower mas...

  8. Search for Neutrino-induced Cascades from Gamma-Ray Bursts with AMANDA

    Science.gov (United States)

    Achterberg, A.; Ackermann, M.; Adams, J.; Ahrens, J.; Andeen, K.; Auffenberg, J.; Bahcall, J. N.; Bai, X.; Baret, B.; Barwick, S. W.; Bay, R.; Beattie, K.; Becka, T.; Becker, J. K.; Becker, K.-H.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Blaufuss, E.; Boersma, D. J.; Bohm, C.; Bolmont, J.; Böser, S.; Botner, O.; Bouchta, A.; Braun, J.; Burgess, C.; Burgess, T.; Castermans, T.; Chirkin, D.; Christy, B.; Clem, J.; Cowen, D. F.; D'Agostino, M. V.; Davour, A.; Day, C. T.; De Clercq, C.; Demirörs, L.; Descamps, F.; Desiati, P.; De Young, T.; Diaz-Velez, J. C.; Dreyer, J.; Dumm, J. P.; Duvoort, M. R.; Edwards, W. R.; Ehrlich, R.; Eisch, J.; Ellsworth, R. W.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Filimonov, K.; Foerster, M. M.; Fox, B. D.; Franckowiak, A.; Gaisser, T. K.; Gallagher, J.; Ganugapati, R.; Geenen, H.; Gerhardt, L.; Goldschmidt, A.; Goodman, J. A.; Gozzini, R.; Griesel, T.; Grullon, S.; Groß, A.; Gunasingha, R. M.; Gurtner, M.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Hardtke, D.; Hardtke, R.; Hart, J. E.; Hasegawa, Y.; Hauschildt, T.; Hays, D.; Heise, J.; Helbing, K.; Hellwig, M.; Herquet, P.; Hill, G. C.; Hodges, J.; Hoffman, K. D.; Hommez, B.; Hoshina, K.; Hubert, D.; Hughey, B.; Hulth, P. O.; Hultqvist, K.; Hülß, J.-P.; Hundertmark, S.; Inaba, M.; Ishihara, A.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Jones, A.; Joseph, J. M.; Kampert, K.-H.; Karg, T.; Karle, A.; Kawai, H.; Kelley, J. L.; Kitamura, N.; Klein, S. R.; Klepser, S.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Kuehn, K.; Labare, M.; Landsman, H.; Leich, H.; Leier, D.; Liubarsky, I.; Lundberg, J.; Lünemann, J.; Madsen, J.; Mase, K.; Matis, H. S.; McCauley, T.; McParland, C. P.; Meli, A.; Messarius, T.; Mészáros, P.; Miyamoto, H.; Mokhtarani, A.; Montaruli, T.; Morey, A.; Morse, R.; Movit, S. M.; Münich, K.; Nahnhauer, R.; Nam, J. W.; Nießen, P.; Nygren, D. R.; Ögelman, H.; Olivas, A.; Patton, S.; Peña-Garay, C.; Pérez de los Heros, C.; Piegsa, A.; Pieloth, D.; Pohl, A. C.; Porrata, R.; Pretz, J.; Price, P. B.; Przybylski, G. T.; Rawlins, K.; Razzaque, S.; Resconi, E.; Rhode, W.; Ribordy, M.; Rizzo, A.; Robbins, S.; Roth, P.; Rott, C.; Rutledge, D.; Ryckbosch, D.; Sander, H.-G.; Sarkar, S.; Schlenstedt, S.; Schmidt, T.; Schneider, D.; Seckel, D.; Semburg, B.; Seo, S. H.; Seunarine, S.; Silvestri, A.; Smith, A. J.; Solarz, M.; Song, C.; Sopher, J. E.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Steffen, P.; Stezelberger, T.; Stokstad, R. G.; Stoufer, M. C.; Stoyanov, S.; Strahler, E. A.; Straszheim, T.; Sulanke, K.-H.; Sullivan, G. W.; Sumner, T. J.; Taboada, I.; Tarasova, O.; Tepe, A.; Thollander, L.; Tilav, S.; Tluczykont, M.; Toale, P. A.; Turčan, D.; van Eijndhoven, N.; Vandenbroucke, J.; Van Overloop, A.; Viscomi, V.; Voigt, B.; Wagner, W.; Walck, C.; Waldmann, H.; Walter, M.; Wang, Y.-R.; Wendt, C.; Wiebusch, C. H.; Wikström, G.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Woschnagg, K.; Xu, X. W.; Yodh, G.; Yoshida, S.; Zornoza, J. D.

    2007-07-01

    Using the neutrino telescope AMANDA-II, we have conducted two analyses searching for neutrino-induced cascades from gamma-ray bursts. No evidence of astrophysical neutrinos was found, and limits are presented for several models. We also present neutrino effective areas which allow the calculation of limits for any neutrino production model. The first analysis looked for a statistical excess of events within a sliding window of 1 or 100 s (for short and long burst classes, respectively) during the years 2001-2003. The resulting upper limit on the diffuse flux normalization times E2 for the Waxman-Bahcall model at 1 PeV is 1.6×10-6 GeV cm-2 s-1 sr-1 (a factor of 120 above the theoretical prediction). For this search 90% of the neutrinos would fall in the energy range 50 TeV to 7 PeV. The second analysis looked for neutrino-induced cascades in coincidence with 73 bursts detected by BATSE in the year 2000. The resulting upper limit on the diffuse flux normalization times E2, also at 1 PeV, is 1.5×10-6 GeV cm-2 s-1 sr-1 (a factor of 110 above the theoretical prediction) for the same energy range. The neutrino-induced cascade channel is complementary to the up-going muon channel. We comment on its advantages for searches of neutrinos from GRBs and its future use with IceCube.

  9. A Measurement of the Branching Ratio and Asymmetry of the Decay Cascade$^{0} \\to \\Sigma ^{0}/gamma$

    CERN Document Server

    Alavi-Harati, A; Arenton, M; Arisaka, K; Averitte, S; Barker, A R; Bellantoni, L; Bellavance, A; Belz, J E; Ben-David, R; Bergman, D R; Blucher, E; Bock, G J; Bown, C; Bright, S T; Cheu, E; Childress, S; Coleman, R; Corcoran, M D; Corti, G; Cox, B; Crisler, M B; Erwin, A R; Ford, R; Glazov, A; Golossanov, A; Graham, G; Graham, J; Hagan, K; Halkiadakis, E; Hamm, J; Hanagaki, K; Hidaka, S; Hsiung, Y B; Jejer, V; Jensen, D A; Kessler, R; Kobrak, H G E; La Due, J; Lath, A; Ledovskoy, A A; McBride, P; Mikelsons, P; Monnier, E; Nakaya, T; Nelson, K S; Nguyen, H; O'Dell, Vivian R; Pang, M; Pordes, R; Prasad, V; Quinn, B; Ramberg, E J; Ray, R E; Roodman, A; Sadamoto, M; Schnetzer, S R; Senyo, K; Shanahan, P; Shawhan, P S; Shields, J; Slater, W; Solomey, Nickolas; Somalwar, S V; Stone, R L; Suzuki, I; Swallow, E C; Taegar, S A; Tesarek, R J; Thomson, G B; Toale, P A; Tripathi, A K; Tschirhart, R S; Turner, S E; Wah, Y W; Wang, J; White, H B; Whitmore, J; Winstein, Bruce D; Winston, R; Yamanaka, T; Zimmerman, E D

    2001-01-01

    We have studied the rare weak radiative hyperon decay Cascade0-->Sigma0/gamma in the KTeV experiment at Fermilab. We have identified 4045 signal events over a background of 804 events. The dominant Cascade0-->Lambda/pi0 decay, which was used for normalization, is the only important background source. An analysis of the acceptance of both modes yields a branching ratio of BR(Cascade0-->Sigma0/gamma)=(3.34 +/- 0.05 +/- 0.09) x 10^(-3). By analyzing the final state decay distributions, we have also determined that the Sigma0 emission asymmetry parameter for this decay is alpha = -0.63 +/- 0.09.

  10. Application of the EXtrapolated Efficiency Method (EXEM) to infer the gamma-cascade detection efficiency in the actinide region

    CERN Document Server

    Ducasse, Q; Mathieu, L; Marini, P; Morillon, B; Aiche, M; Tsekhanovich, I

    2015-01-01

    The study of transfer-induced gamma-decay probabilities is very useful for understanding the surrogate-reaction method and, more generally, for constraining statistical-model calculations. One of the main difficulties in the measurement of gamma-decay probabilities is the determination of the gamma-cascade detection efficiency. In [Nucl. Instrum. Meth. A 700, 59 (2013)] we developed the Extrapolated Efficiency Method (EXEM), a new method to measure this quantity. In this work, we have applied, for the first time, the EXEM to infer the gamma-cascade detection efficiency in the actinide region. In particular, we have considered the 238U(d,p)239U and 238U(3He,d)239Np reactions. We have performed Hauser-Feshbach calculations to interpret our results and to verify the hypothesis on which the EXEM is based. The determination of fission and gamma-decay probabilities of 239Np below the neutron separation energy allowed us to validate the EXEM.

  11. Neuronal intranuclear inclusion disease and juvenile parkinsonism.

    Science.gov (United States)

    O'Sullivan, J D; Hanagasi, H A; Daniel, S E; Tidswell, P; Davies, S W; Lees, A J

    2000-09-01

    Juvenile parkinsonism (onset age boy who presented with asymmetric arm tremor and bulbar symptoms. His paternal great aunt had parkinsonism with onset at age 22 years. Examination revealed parkinsonism in the absence of additional neurologic signs except for delayed pupillary responses to light. He responded well to levodopa but developed motor fluctuations and disabling dyskinesias after 3 years of treatment. Following attempted withdrawal of levodopa at age 24 years, he developed severe aspiration pneumonia complicated by cardiorepiratory arrests and he died 6 months later. At autopsy, the dominant histologic feature was wide-spread neuronal hyaline intranuclear inclusions. Neuronal depletion was observed in the substantia nigra, locus ceruleus, and, to a lesser extent, in the frontal cortex, and inclusions were particularly prominent in these areas. Inclusions were immunoreactive for ubiquitin and were typical of those seen in neuronal intranuclear inclusion disease (NIID), a rare, multisytem neurodegenerative disease. NIID should be considered in the differential diagnosis of juvenile parkinsonism. A link between NIID and hereditary neurodegenerative disorders characterized by expanded polyglutamine tracts is supported by the similar appearance of intranuclear inclusions in both conditions and by a family history in some cases of NIID. PMID:11009211

  12. QED cascade induced by high energy $\\gamma$ photon in strong laser field

    CERN Document Server

    Tang, Suo; Wang, Hong-Yu; Xie, Bai-Song

    2013-01-01

    The QED cascade induced by the two counter-propagating lasers is studied. It is demonstrated that the probability of a seed-photon to create a pair is much larger than that of a seed-electron. By analyzing the dynamic characteristics of the electron and positron created by the seed-photon, it is found that the created particles are more probable to emit photons than the seed-electron. With these result, further more, we also demonstrate that the QED cascade can be easier to be triggered by the seed-photon than by the seed-electron with the same incident energy and the same laser.

  13. Monte Carlo simulation for the electron cascade due to gamma rays in semiconductor radiation detectors

    International Nuclear Information System (INIS)

    A Monte Carlo code was developed for simulating the electron cascade in radiation detector materials. The electron differential scattering cross sections were derived from measured electron energy-loss and optical spectra, making the method applicable for a wide range of materials. The detector resolution in a simplified model system shows dependence on the bandgap, the plasmon strength and energy, and the valence band width. In principle, these parameters could be optimized to improve detector performance. The intrinsic energy resolution was calculated for three semiconductors: silicon (Si), gallium arsenide (GaAs), and zinc telluride (ZnTe). Setting the ionization thresholds for electrons and holes is identified as a critical issue, as this strongly affects both the average electron-hole pair energy w and the Fano factor F. Using an ionization threshold from impact ionization calculations as an effective bandgap yields pair energies that are well matched to measured values. Fano factors of 0.091 (Si), 0.100 (GaAs), and 0.075 (ZnTe) were calculated. The Fano factor calculated for silicon using this model was lower than some results from past simulations and experiments. This difference could be attributed to problems in simulating inter-band transitions and the scattering of low-energy electrons.

  14. Monte Carlo simulation for the electron cascade due to gamma rays in semiconductor radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, Raman D.; Miranda, Ryan; Rez, Peter [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States)

    2012-03-15

    A Monte Carlo code was developed for simulating the electron cascade in radiation detector materials. The electron differential scattering cross sections were derived from measured electron energy-loss and optical spectra, making the method applicable for a wide range of materials. The detector resolution in a simplified model system shows dependence on the bandgap, the plasmon strength and energy, and the valence band width. In principle, these parameters could be optimized to improve detector performance. The intrinsic energy resolution was calculated for three semiconductors: silicon (Si), gallium arsenide (GaAs), and zinc telluride (ZnTe). Setting the ionization thresholds for electrons and holes is identified as a critical issue, as this strongly affects both the average electron-hole pair energy w and the Fano factor F. Using an ionization threshold from impact ionization calculations as an effective bandgap yields pair energies that are well matched to measured values. Fano factors of 0.091 (Si), 0.100 (GaAs), and 0.075 (ZnTe) were calculated. The Fano factor calculated for silicon using this model was lower than some results from past simulations and experiments. This difference could be attributed to problems in simulating inter-band transitions and the scattering of low-energy electrons.

  15. Developments in gamma-ray spectrometry: systems, software, and methods-II. 1. Using Generic Detector Characterization Templates for Cascade Summing Correction

    International Nuclear Information System (INIS)

    In gamma-ray spectroscopy, the need to correct certain nuclide activities for the effect of true coincidence summing (or cascade summing) has long been recognized. To correct for the effects of cascade summing, recently, Koskelo et al. described a method based on characterizing the high-purity germanium (HPGe) detector response using mathematical techniques. An accurate correction, however, requires that the HPGe detector used in the measurement be characterized for its response. An accurate characterization of the detector response entails time-consuming computer simulations as well as experimental measurements. This work describes the effort to determine the feasibility of employing a discrete number of generic detector response characterizations for carrying out cascade summing corrections on gamma-ray spectra obtained with non-characterized HPGe detectors. The present study compares data obtained from two detector islands. Each island consists of a number of generic detectors and a reference detector-all of which have been fully characterized using the methods given in Refs. 8, 9, and 10. In the first island, detectors with relative efficiencies in the 10 to 35% range were grouped. The reference detector was an HPGe detector with 20% relative efficiency. In the second island, detectors with relative efficiencies between 40 and 100% were grouped; the reference detector was an 86% HPGe detector. Further, each island was made up of detectors with different active diameters. The cascade summing correction algorithm then was applied to obtain actual correction factors for several nuclides (60Co, 88Y, 110Ag, 152Eu, and 82Br) and several detector sizes. The correction factors were determined for a point source geometry, with the source located at the center of the detector end-cap. This geometry was chosen to maximize the true coincidence summing effect. Such a worst-case scenario allows one to establish the minimum number of discrete generic characterizations

  16. New possibilities for improving the accuracy of parameter calculations for cascade gamma-ray decay of heavy nuclei

    International Nuclear Information System (INIS)

    The level density and radiative strength functions which accurately reproduce the experimental intensity of two- step cascades after thermal neutron capture and the total radiative widths of the compound states were applied to calculate the total γ-ray spectra from the (n,γ) reaction. In some cases, analysis showed far better agreement with experiment and gave insight into possible ways in which these parameters need to be corrected for further improvement of calculation accuracy for the cascade γ-decay of heavy nuclei. (author)

  17. Covariance analysis of selection rules governing the gamma-decay cascades of the rotational nucleus sup 1 sup 6 sup 4 Yb

    CERN Document Server

    Leoni, S; Bracco, A; Frattini, S; Montingelli, G; Vigezzi, E; Bergström, M H; Hagemann, G B; Herskind, B; Matsuo, M

    2000-01-01

    The gamma-cascades feeding specific intrinsic configurations of sup 1 sup 6 sup 4 Yb are studied making use of a statistical analysis of counts fluctuations in gamma-gamma coincident spectra. In particular, variance and covariance spectra are obtained starting from the measured (0,+), (0,-) and (1,-) gate-selected matrices. The analysis of the first ridge of the spectra yields about 25 excited bands carrying rotational energy correlations for the total spectrum, and about 10 in coincidence with each of the (alpha,pi) configurations. The covariance of count fluctuations between the different (alpha,pi) gates is expressed by an experimental correlation coefficient, r, which measures the degree of sharing of decay paths through the excited bands, and thereby the extent to which selection rules are obeyed by the decay. The correlation coefficient is around r approx 0.3 for the ridge, and also in general rather small for valley fluctuations. Only at the highest valley energies, a tendency to larger correlation coe...

  18. Experimental and Monte Carlo study of gamma-ray spectrometry: correction of cascade and matrix effects in environmental measurements

    International Nuclear Information System (INIS)

    Precisely measuring weakly radioactive samples by gamma-ray spectrometry requires optimizing the detection geometry and knowledge of the gamma-ray decay scheme. One can thus increase the counting rate and reduce the statistical uncertainty of the spectral peaks used to determine radioisotope activities. However, an increased sample volume requires a correction for the self-absorption of γ-rays in the sample itself, and approaching a sample to the detector gives rise to coincidence summing. MCNPX simulations permitted finding the separate influence of sample density and effective atomic number of the sample in the attenuation of photons with energies less than 100 keV. Peak-summing corrections were obtained with MCNPX, GESPCOR and ETNA. Thus a data base for 244 radionuclides could be established for SG50 and SG500 geometries in contact with a planar detector. In an application of the results to the health physics domain, construction materials were analyzed. Naturally-occurring Uranium-238, Thorium-232 and Potassium-40 activities were identified and corrected for the above-mentioned effects in order to evaluate the risk indexes, the absorbed dose and the annual effective dose received from different dimensions built of these materials. MCNPX simulations corroborated the model used to calculate the absorbed dose and gave its distribution in an enclosed space. The results obtained are within the recommended norms. (author)

  19. Biphasic Chromatin Structure and FISH Signals Reflect Intranuclear Order

    Directory of Open Access Journals (Sweden)

    Jyoti P. Chaudhuri

    2005-01-01

    Full Text Available Background and Aim: One of the two parental allelic genes may selectively be expressed, regulated by imprinting, X-inactivation or by other less known mechanisms. This study aims to reflect on such genetic mechanisms. Materials and Methods: Slides from short term cultures or direct smears of blood, bone marrow and amniotic fluids were hybridized with FISH probes singly, combined or sequentially. Two to three hundred cells were examined from each preparation. Results and Aignificance: A small number of cells (up to about 5%, more frequent in leukemia cases, showed the twin features: (1 nuclei with biphasic chromatin, one part decondensed and the other condensed; and (2 homologous FISH signals distributed equitably in those two regions. The biphasic chromatin structure with equitable distribution of the homologous FISH signals may correspond to the two sets of chromosomes, supporting observations on ploidywise intranuclear order. The decondensed chromatin may relate to enhanced transcriptions or advanced replications. Conclusions: Transcriptions of only one of the two parental genomes cause allelic exclusion. Genomes may switch with alternating monoallelic expression of biallelic genes as an efficient genetic mechanism. If genomes fail to switch, allelic exclusion may lead to malignancy. Similarly, a genome-wide monoallelic replication may tilt the balance of heterozygosity resulting in aneusomy, initiating early events in malignant transformation and in predicting cancer mortality.

  20. Intranuclear Delivery of a Novel Antibody-Derived Radiosensitizer Targeting the DNA-Dependent Protein Kinase Catalytic Subunit

    Energy Technology Data Exchange (ETDEWEB)

    Xiong Hairong [Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, Augusta, GA (Georgia); State Key Laboratory of Virology, Institute of Medical Virology, Wuhan University School of Medicine, Wuhan (China); Lee, Robert J. [Division of Pharmaceutics, College of Pharmacy, Ohio State University, Columbus, OH (United States); Haura, Eric B. [Thoracic Oncology and Experimental Therapeutics Programs, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL (United States); Edwards, John G. [Apeliotus Technologies, Inc., Atlanta, GA (United States); Dynan, William S. [Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, Augusta, GA (Georgia); Li Shuyi, E-mail: sli@georgiahealth.edu [Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, Augusta, GA (Georgia); Apeliotus Technologies, Inc., Atlanta, GA (United States)

    2012-07-01

    Purpose: To inhibit DNA double-strand break repair in tumor cells by delivery of a single-chain antibody variable region fragment (ScFv 18-2) to the cell nucleus. ScFv 18-2 binds to a regulatory region of the DNA-dependent protein kinase (DNA-PK), an essential enzyme in the nonhomologous end-joining pathway, and inhibits DNA end-joining in a cell-free system and when microinjected into single cells. Development as a radiosensitizer has been limited by the lack of a method for intranuclear delivery to target cells. We investigated a delivery method based on folate receptor-mediated endocytosis. Methods and Materials: A recombinant ScFv 18-2 derivative was conjugated to folate via a scissile disulfide linker. Folate-ScFv 18-2 was characterized for its ability to be internalized by tumor cells and to influence the behavior of ionizing radiation-induced repair foci. Radiosensitization was measured in a clonogenic survival assay. Survival curves were fitted to a linear-quadratic model, and between-group differences were evaluated by an F test. Sensitization ratios were determined based on mean inhibitory dose. Results: Human KB and NCI-H292 lung cancer cells treated with folate-conjugated ScFv 18-2 showed significant radiosensitization (p < 0.001). Sensitization enhancement ratios were 1.92 {+-} 0.42 for KB cells and 1.63 {+-} 0.13 for NCI-H292 cells. Studies suggest that treatment inhibits repair of radiation-induced DSBs, as evidenced by the persistence of {gamma}-H2AX-stained foci and by inhibition of staining with anti-DNA-PKcs phosphoserine 2056. Conclusions: Folate-mediated endocytosis is an effective method for intranuclear delivery of an antibody-derived DNA repair inhibitor.

  1. Intranuclear localization and UV response of ERCC5/XPG protein

    International Nuclear Information System (INIS)

    The human ERCC5/XPG protein is defective in the hereditary genetic disorder xeroderma pigmentosum, group-G. The XPG gene encodes a single-strand DNA endonuclease which is essential for the incision step of nucleotide excision repair for a wide variety of DNA damages. We have shown previously by indirect immunofluorescence and biochemical fractionation that the XPG protein is localized in the nucleus, in discrete foci, and probably associated with the nuclear matrix. However, the intranuclear localization of XPG is markedly altered for a short time after UV irradiation. Here, we report the identification of XPG protein regions involved in the UV response, and its putative nuclear localization signals (NLS) using a B-galactosidase (B-gal) reporter gene system. Control and fusion reporter genes were expressed in Hela S3 cells after CaPO4 transfection. B-gal protein was detected by indirect immuno-fluorescence using an anti B-gal monoclonal antibody and FITC-labeled goat anti-mouse antiserum. Two NLS peptides of the XPG carboxy-terminal region (AA 1029-1069 and 1146-1186 term) were shown to independently localize B-gal fusion proteins to the nucleus (>90%). The C-terminus peptide was observed to further localize B-gal into nuclear foci and the perinucleolar regions. When B-gal was fused with two copies of the C-terminal NLS, in tandem, B-gal was extensively sublocalized to the perinucleolar regions. Shortly after cell UV irradiation (5 J/m2) this B-gal fusion protein became dissociated from the perinucleolar regions whereupon it was distributed throughout the nucleus. Within 6 hours post-irradiation, the fusion protein reassociated again with the perinucleolar regions. These observations confirm and extend a similar UV response of endogenous XPG protein in UV-irradiation human cells. The involvement of XPG protein and its UV responses will be discussed in context of models nuclear matrix and preferential DNA repair in actively transcribed genes

  2. Intranuclear localization and UV response of ERCC5/XPG protein

    Energy Technology Data Exchange (ETDEWEB)

    Park, M.S.; Marrone, B.L.; MacInnes, M.A. [Los Alamos National Laboratory, NM (United States)] [and others

    1995-11-01

    The human ERCC5/XPG protein is defective in the hereditary genetic disorder xeroderma pigmentosum, group-G. The XPG gene encodes a single-strand DNA endonuclease which is essential for the incision step of nucleotide excision repair for a wide variety of DNA damages. We have shown previously by indirect immunofluorescence and biochemical fractionation that the XPG protein is localized in the nucleus, in discrete foci, and probably associated with the nuclear matrix. However, the intranuclear localization of XPG is markedly altered for a short time after UV irradiation. Here, we report the identification of XPG protein regions involved in the UV response, and its putative nuclear localization signals (NLS) using a B-galactosidase (B-gal) reporter gene system. Control and fusion reporter genes were expressed in Hela S3 cells after CaPO{sub 4} transfection. B-gal protein was detected by indirect immuno-fluorescence using an anti B-gal monoclonal antibody and FITC-labeled goat anti-mouse antiserum. Two NLS peptides of the XPG carboxy-terminal region (AA 1029-1069 and 1146-1186 term) were shown to independently localize B-gal fusion proteins to the nucleus (>90%). The C-terminus peptide was observed to further localize B-gal into nuclear foci and the perinucleolar regions. When B-gal was fused with two copies of the C-terminal NLS, in tandem, B-gal was extensively sublocalized to the perinucleolar regions. Shortly after cell UV irradiation (5 J/m{sup 2}) this B-gal fusion protein became dissociated from the perinucleolar regions whereupon it was distributed throughout the nucleus. Within 6 hours post-irradiation, the fusion protein reassociated again with the perinucleolar regions. These observations confirm and extend a similar UV response of endogenous XPG protein in UV-irradiation human cells. The involvement of XPG protein and its UV responses will be discussed in context of models nuclear matrix and preferential DNA repair in actively transcribed genes.

  3. Albedo of photons in high energy electromagnetic and hadronic cascades

    International Nuclear Information System (INIS)

    The albedo of photons in electromagnetic cascades is simulated. A simple model of back current photons generation and propagation in electromagnetic cascades is considered which satisfactorily describes the general features of albedo behavior. The contribution to the photonic albedo of electromagnetic subshowers generated by high energy gamma-quanta from π0 decays in the hadron initiated cascade is evaluated. (orig.)

  4. Intranuclear sphingomyelin is associated with transcriptionally active chromatin and plays a role in nuclear integrity

    NARCIS (Netherlands)

    C. Scassellati; E. Albi; D. Cmarko; C. Tiberi; J. Cmarkova; C. Bouchet‑Marquis; P.J. Verschure; R. van Driel; M. Viola Magni; S. Fakan

    2010-01-01

    Background information. Sphingomyelin is one of the major phospholipids in the cell nucleus. However, its intranuclear distribution with regard to different functional nuclear domains as well as its possible involvement in the nuclear functional architecture remains to be elucidated. Results. We car

  5. Time evolution of cascade decay

    CERN Document Server

    Boyanovsky, Daniel

    2014-01-01

    We study non-perturbatively the time evolution of cascade decay for generic fields $\\pi \\rightarrow \\phi_1\\phi_2\\rightarrow \\phi_2\\chi_1\\chi_2$ and obtain the time dependence of amplitudes and populations for the resonant and final states. We analyze in detail the different time scales and the manifestation of unitary time evolution in the dynamics of production and decay of resonant intermediate and final states. The probability of occupation (population) ``flows'' as a function of time from the initial to the final states. When the decay width of the parent particle $\\Gamma_\\pi$ is much larger than that of the intermediate resonant state $\\Gamma_{\\phi_1}$ there is a ``bottleneck'' in the flow, the population of resonant states builds up to a maximum at $t^* = \\ln[\\Gamma_\\pi/\\Gamma_{\\phi_1}]/(\\Gamma_\\pi-\\Gamma_{\\phi_1})$ nearly saturating unitarity and decays to the final state on the longer time scale $1/\\Gamma_{\\phi_1}$. As a consequence of the wide separation of time scales in this case the cascade decay ...

  6. Disruption of NAD~+ binding site in glyceraldehyde 3-phosphate dehydrogenase affects its intranuclear interactions

    Institute of Scientific and Technical Information of China (English)

    Manali; Phadke; Natalia; Krynetskaia; Anurag; Mishra; Carlos; Barrero; Salim; Merali; Scott; A; Gothe; Evgeny; Krynetskiy

    2015-01-01

    AIM:To characterize phosphorylation of human glyceraldehyde 3-phosphate dehydrogenase(GAPDH),and mobility of GAPDH in cancer cells treated with chemotherapeutic agents. METHODS:We used proteomics analysis to detect and characterize phosphorylation sites within human GAPDH. Site-specific mutagenesis and alanine scanning was then performed to evaluate functional significance of phosphorylation sites in the GAPDH polypeptide chain. Enzymatic properties of mutated GAPDH variants were assessed using kinetic studies. Intranuclear dynamics parameters(diffusion coefficient and the immobile fraction) were estimated using fluorescence recovery after photobleaching(FRAP) experiments and confocal microscopy. Molecular modeling experiments were performed to estimate the effects of mutations on NAD+ cofactor binding.RESULTS:Using MALDI-TOF analysis,we identified novel phosphorylation sites within the NAD+ binding center of GAPDH at Y94,S98,and T99. Using polyclonal antibody specific to phospho-T99-containing peptide within GAPDH,we demonstrated accumulation of phospho-T99-GAPDH inthe nuclear fractions of A549,HCT116,and SW48 cancer cel s after cytotoxic stress. We performed site-mutagenesis,and estimated enzymatic properties,intranuclear distribution,and intranuclear mobility of GAPDH mutated variants. Site-mutagenesis at positions S98 and T99 in the NAD+ binding center reduced enzymatic activity of GAPDH due to decreased affinity to NAD+(Km = 741 ± 257 μmol/L in T99 I vs 57 ± 11.1 μmol/L in wild type GAPDH. Molecular modeling experiments revealed the effect of mutations on NAD+ binding with GAPDH. FRAP(fluorescence recovery after photo bleaching) analysis showed that mutations in NAD+ binding center of GAPDH abrogated its intranuclear interactions. CONCLUSION:Our results suggest an important functional role of phosphorylated amino acids in the NAD+ binding center in GAPDH interactions with its intranuclear partners.

  7. Learning Cascading

    CERN Document Server

    Covert, Michael

    2015-01-01

    This book is intended for software developers, system architects and analysts, big data project managers, and data scientists who wish to deploy big data solutions using the Cascading framework. You must have a basic understanding of the big data paradigm and should be familiar with Java development techniques.

  8. Nucleospora cyclopteri n. sp., an intranuclear microsporidian infecting wild lumpfish, Cyclopterus lumpus L., in Icelandic waters

    OpenAIRE

    Freeman, Mark A.; Kasper, Jacob M.; Kristmundsson, Árni

    2013-01-01

    Background Commercial fisheries of lumpfish Cyclopterus lumpus have been carried out in Iceland for centuries. Traditionally the most valuable part is the eggs which are harvested for use as a caviar substitute. Previously reported parasitic infections from lumpfish include an undescribed intranuclear microsporidian associated with abnormal kidneys and mortalities in captive lumpfish in Canada. During Icelandic lumpfish fisheries in spring 2011, extensive enlargements to the kidneys were obse...

  9. INTRANUCLEAR MATRIX METALLOPROTEINASES PROMOTE DNA DAMAGE AND APOPTOSIS INDUCED BY OXYGEN–GLUCOSE DEPRIVATION IN NEURONS

    Science.gov (United States)

    HILL, J. W.; PODDAR, R.; THOMPSON, J. F.; ROSENBERG, G. A.; YANG, Y.

    2016-01-01

    Degradation of the extracellular matrix by elevated matrix metalloproteinase (MMP) activity following ischemia/reperfusion is implicated in blood–brain barrier disruption and neuronal death. In contrast to their characterized extracellular roles, we previously reported that elevated intranuclear MMP-2 and -9 (gelatinase) activity degrades nuclear DNA repair proteins and promotes accumulation of oxidative DNA damage in neurons in rat brain at 3-h reperfusion after ischemic stroke. Here, we report that treatment with a broad-spectrum MMP inhibitor significantly reduced neuronal apoptosis in rat ischemic hemispheres at 48-h reperfusion after a 90-min middle cerebral artery occlusion (MCAO). Since extracellular gelatinases in brain tissue are known to be neurotoxic during acute stroke, the contribution of intranuclear MMP-2 and -9 activities in neurons to neuronal apoptosis has been unclear. To confirm and extend our in vivo observations, oxygen–glucose deprivation (OGD), an in vitro model of ischemia/reperfusion, was employed. Primary cortical neurons were subjected to 2-h OGD with reoxygenation. Increased intranuclear gelatinase activity was detected immediately after reoxygenation onset and was maximal at 24 h, while extracellular gelatinase levels remained unchanged. We detected elevated levels of both MMP-2 and -9 in neuronal nuclear extracts and gelatinase activity in neurons co-localized primarily with MMP-2. We found a marked decrease in PARP1, XRCC1, and OGG1, and decreased PARP1 activity. Pretreatment of neurons with selective MMP-2/9 inhibitor II significantly decreased gelatinase activity and downregulation of DNA repair enzymes, decreased accumulation of oxidative DNA damage, and promoted neuronal survival after OGD. Our results confirm the nuclear localization of gelatinases and their nuclear substrates observed in an animal stroke model, further supporting a novel role for intranuclear gelatinase activity in an intrinsic apoptotic pathway in neurons

  10. Investigating the intra-nuclear cascade process using the reaction 136Xe on deuterium at 500 AMeV

    Directory of Open Access Journals (Sweden)

    Rejmund F.

    2010-10-01

    Full Text Available More than 600 residual nuclei, formed in the spallation of 136Xe projectiles impinging on deuterium at 500 AMeV of incident energy, have been unambiguously identified and their production cross sections have been determined with high accuracy. By comparing these data to others previously measured for the reactions 136Xe  +  p at 1 AGeV and 136Xe  +  p at 500 AMeV we investigated the role that neutrons play in peripheral collisions and to understand the energy dissipation in frontal collisions in spallation reactions.

  11. Cascading Cosmology

    CERN Document Server

    Agarwal, Nishant; Khoury, Justin; Trodden, Mark

    2009-01-01

    We develop a fully covariant, well-posed 5D effective action for the 6D cascading gravity brane-world model, and use this to study cosmological solutions. We obtain this effective action through the 6D decoupling limit, in which an additional scalar degree mode, \\pi, called the brane-bending mode, determines the bulk-brane gravitational interaction. The 5D action obtained this way inherits from the sixth dimension an extra \\pi self-interaction kinetic term. We compute appropriate boundary terms, to supplement the 5D action, and hence derive fully covariant junction conditions and the 5D Einstein field equations. Using these, we derive the cosmological evolution induced on a 3-brane moving in a static bulk. We study the strong- and weak-coupling regimes analytically in this static ansatz, and perform a complete numerical analysis of our solution. Although the cascading model can generate an accelerating solution in which the \\pi field comes to dominate at late times, the presence of a critical singularity prev...

  12. ORGANIZACIÓN INTRANUCLEAR DE PROTEÍNAS SR EN VERTEBRADOS

    OpenAIRE

    María de Lourdes Segura-Valdez; Cristina Negrete García; Yamilka Rodríguez Gómez; Ana Sánz Ochotorena; Reyna Lara Martínez; José de Jesús Moncayo Sahagún; Claudina María Gómez Arizmendi; Luis F. Jiménez-García

    2007-01-01

    En eucariontes, el mRNA se forma a partir de un transcrito primario o pre-mRNA que madura mediante tres pasos que son la 7-metil-guanilación del extremo 5., la poliadenilación del extremo 3. y el splicing o corte de intrones y ligado de los exones resultantes. Estos pasos requieren de diversos factores cuya organización celular observada con el microscopio de epifluorescencia corresponde a una distribución intranuclear conocida como patrón moteado (speckles), que incluye regiones de distribuc...

  13. Protein complex formation and intranuclear dynamics of NAC1 in cancer cells.

    Science.gov (United States)

    Nakayama, Naomi; Kato, Hiroaki; Sakashita, Gyosuke; Nariai, Yuko; Nakayama, Kentaro; Kyo, Satoru; Urano, Takeshi

    2016-09-15

    Nucleus accumbens-associated protein 1 (NAC1) is a cancer-related transcription regulator protein that is also involved in the pluripotency and differentiation of embryonic stem cells. NAC1 is overexpressed in various carcinomas including ovarian, cervical, breast, and pancreatic carcinomas. NAC1 knock-down was previously shown to result in the apoptosis of ovarian cancer cell lines and to rescue their sensitivity to chemotherapy, suggesting that NAC1 may be a potential therapeutic target, but protein complex formation and the dynamics of intranuclear NAC1 in cancer cells remain poorly understood. In this study, analysis of HeLa cell lysates by fast protein liquid chromatography (FPLC) on a sizing column showed that the NAC1 peak corresponded to an apparent molecular mass of 300-500 kDa, which is larger than the estimated molecular mass (58 kDa) of the protein. Furthermore, live cell photobleaching analyses with green fluorescent protein (GFP)-fused NAC1 proteins revealed the intranuclear dynamics of NAC1. Collectively our results demonstrate that NAC1 forms a protein complex to function as a transcriptional regulator in cancer cells.

  14. Protein complex formation and intranuclear dynamics of NAC1 in cancer cells.

    Science.gov (United States)

    Nakayama, Naomi; Kato, Hiroaki; Sakashita, Gyosuke; Nariai, Yuko; Nakayama, Kentaro; Kyo, Satoru; Urano, Takeshi

    2016-09-15

    Nucleus accumbens-associated protein 1 (NAC1) is a cancer-related transcription regulator protein that is also involved in the pluripotency and differentiation of embryonic stem cells. NAC1 is overexpressed in various carcinomas including ovarian, cervical, breast, and pancreatic carcinomas. NAC1 knock-down was previously shown to result in the apoptosis of ovarian cancer cell lines and to rescue their sensitivity to chemotherapy, suggesting that NAC1 may be a potential therapeutic target, but protein complex formation and the dynamics of intranuclear NAC1 in cancer cells remain poorly understood. In this study, analysis of HeLa cell lysates by fast protein liquid chromatography (FPLC) on a sizing column showed that the NAC1 peak corresponded to an apparent molecular mass of 300-500 kDa, which is larger than the estimated molecular mass (58 kDa) of the protein. Furthermore, live cell photobleaching analyses with green fluorescent protein (GFP)-fused NAC1 proteins revealed the intranuclear dynamics of NAC1. Collectively our results demonstrate that NAC1 forms a protein complex to function as a transcriptional regulator in cancer cells. PMID:27424155

  15. Karyomegaly and intranuclear inclusions in the renal tubules of sentinel ICR mice (mus musculus).

    Science.gov (United States)

    Baze, Wallace B; Steinbach, Thomas J; Fleetwood, Michelle L; Blanchard, Terrell W; Barnhart, Kirstin F; McArthur, Mark J

    2006-10-01

    Among 585 sentinel ICR mice (Mus musculus), 8 (7 female, 1 male) had unusual microscopic lesions in the kidney. Light microscopy revealed occasional tubular epithelial cells with large, karyomegalic nuclei that contained intranuclear inclusions and marginated chromatin. These cells were randomly present in the cortex and medulla but were more prominent near the corticomedullary junc tion. Rare pyknotic cells and mild interstitial infiltrates of lymphocytes and plasma cells were associated with occasional foci of abnormal cells. Electron microscopy performed on 2 (1 female, 1 male) of the mice demonstrated intranuclear inclusions composed of abundant flocculent, electron-lucent material. No viral particles or other pathogens were identified. General health monitoring that included serology, microbiology, parasitology, necropsy, and histopathology was negative for pathogens. Polymerase chain reaction-based testing for polyomavirus and immunohistochemistry for adenovirus were performed on 5 of the 7 female mice; all were negative for both viruses. In light of microscopy findings and the lack of evidence for an infectious agent, the tubular lesions were considered degenerative changes, possibly due to a toxic insult. The cause and significance of the findings in these mice can not be explained fully.

  16. Intranuclear Pseudo-inclusions and Grooves in Fine Needle Aspiration Cytology of Pulmonary Carcinoid Tumor.

    Science.gov (United States)

    Mokhtari, Maral; Kumar, Perikala Vijayananda

    2016-02-01

    Cytologic findings of pulmonary carcinoid have been well described. We report new cytological findings in a case of carcinoid tumor. The patient is a 36-year-old man presenting with hemoptysis of about six months in duration. Chest CT scans showed a well-defined round polypoid lesion measuring 1 × 1 cm within the right upper lobe of the bronchus with hyperinflation of the right upper lobe. Trans-bronchial fine needle aspiration and biopsy were done. Cytologic smears showed isolated and loose clusters of uniform round to spindle shape cells with round centrally located nuclei, fine granular (salt and pepper) chromatin and pale cytoplasm. Intranuclear pseudo-inclusions and grooves were seen in some tumor cells. No mitotic figures or necrosis were evident. A cytological diagnosis of carcinoid tumor was made and histopathologic examination and subsequent immunohistochemical study confirmed the diagnosis. Carcinoid tumor may be reliably diagnosed on fine needle aspiration cytology smears. Intranuclear pseudo-inclusions and grooves may be evident in tumor cells. PMID:26838088

  17. Intranuclear bundles of microfilaments and microtubules in chromaffin cells of the auricle of the heart of a lungfish, Protopterus aethiopicus.

    Science.gov (United States)

    Scheuermann, D W; Adriaensen, D; De Groodt-Lasseel, M H

    1988-01-01

    Intranuclear microtubular-microfilamentous rod-like inclusions were investigated in chromaffin cells of the auricle of the heart of lungfishes. In conventional electron microscopy, these inclusions reveal a wide variety in appearance, depending on their orientation to the plane of sectioning. Whereas originally they were merely interpreted as a bundle of microfilaments, application of a goniometer stage showed the rod- or spindle-shaped intranuclear inclusions to have a basic substructure of parallel arranged microtubules among microfilaments, which are clearly connected to chromatin granules, occasionally penetrating dense areas of chromatin. The chemical nature and biological significance of these structures, which so far remain enigmatic, are discussed. PMID:3227775

  18. Memory Loss and Frontal Cognitive Dysfunction in a Patient with Adult-onset Neuronal Intranuclear Inclusion Disease.

    Science.gov (United States)

    Araki, Kunihiko; Sone, Jun; Fujioka, Yusuke; Masuda, Michihito; Ohdake, Reiko; Tanaka, Yasuhiro; Nakamura, Tomohiko; Watanabe, Hirohisa; Sobue, Gen

    2016-01-01

    Neuronal intranuclear inclusion disease (NIID) is an uncommon progressive neurodegenerative disorder. Adult-onset NIID can result in prominent dementia. We herein describe the case of a 74-year-old man who presented with dementia, cerebellar ataxia, neuropathy, and autonomic dysfunction. Diffusion-weighted imaging showed hyperintensity of the corticomedullary junction. Fluid-attenuated inversion recovery images showed frontal-dominant white matter hyperintensity. NIID was diagnosed from the presence of intranuclear inclusions in a skin biopsy sample. Neuropsychological testing revealed memory loss and frontal cognitive dysfunction, especially in relation to language and executive functions. We were therefore able to confirm the association of NIID with cognitive dysfunction. PMID:27523009

  19. Validation of the intra-nuclear-cascade-evaporation model for particle production

    International Nuclear Information System (INIS)

    The intranuclear-cascade-evaporation model of HETC/KFA-1 has been used to predict the neutron production from nonelastic interactions of protons with several target materials: U, Pb, Ta, In, Nb, Fe, Al and C. These model predictions for a 590 MeV proton beam were compared with measurements of Cierjacks et al. made at the SIN cyclotron. In general the model predicts approximately the correct neutron production in the evaporation region, whereas in the high energy region (Esub(n) > 20 MeV) there are systematic discrepancies between measurement and model predictions, which tend to increase with increasing neutron energy and increasing emission angle. (orig.)

  20. THERMOSTABILITY OF A NUCLEAR-TARGETED LUCIFERASE EXPRESSED IN MAMMALIAN-CELLS - DESTABILIZING INFLUENCE OF THE INTRANUCLEAR MICROENVIRONMENT

    NARCIS (Netherlands)

    MICHELS, AA; NGUYEN, VT; KONINGS, AW; KAMPINGA, HH; BENSAUDE, O

    1995-01-01

    Protein denaturation and aggregation are most likely the cause for the noxious effects of heat shock, There are some indications that the nucleus is one of the most sensitive cellular compartments, To test the possibility that the intranuclear microenvironment might be detrimental to the heat stabil

  1. Intranuclear interactomic inhibition of NF-κB suppresses LPS-induced severe sepsis

    International Nuclear Information System (INIS)

    Suppression of nuclear factor-κB (NF-κB) activation, which is best known as a major regulator of innate and adaptive immune responses, is a potent strategy for the treatment of endotoxic sepsis. To inhibit NF-κB functions, we designed the intra-nuclear transducible form of transcription modulation domain (TMD) of RelA (p65), called nt-p65-TMD, which can be delivered effectively into the nucleus without influencing the cell viability, and work as interactomic inhibitors via disruption of the endogenous p65-mediated transcription complex. nt-p65-TMD effectively inhibited the secretion of pro-inflammatory cytokines, including TNF-α, IL-1β, or IL-6 from BV2 microglia cells stimulated by lipopolysaccharide (LPS). nt-p65-TMD did not inhibit tyrosine phosphorylation of signaling mediators such as ZAP-70, p38, JNK, or ERK involved in T cell activation, but was capable of suppressing the transcriptional activity of NF-κB without the functional effect on that of NFAT upon T-cell receptor (TCR) stimulation. The transduced nt-p65-TMD in T cell did not affect the expression of CD69, however significantly inhibited the secretion of T cell-specific cytokines such as IL-2, IFN-γ, IL-4, IL-17A, or IL-10. Systemic administration of nt-p65-TMD showed a significant therapeutic effect on LPS-induced sepsis model by inhibiting pro-inflammatory cytokines secretion. Therefore, nt-p65-TMD can be a novel therapeutics for the treatment of various inflammatory diseases, including sepsis, where a transcription factor has a key role in pathogenesis, and further allows us to discover new functions of p65 under normal physiological condition without genetic alteration. - Highlights: • The nt-p65-TMD is intra-nuclear interactomic inhibitor of endogenous p65. • The nt-p65-TMD effectively inhibited the secretion of pro-inflammatory cytokines. • The excellent therapeutic potential of nt-p65-TMD was confirmed in sepsis model

  2. Protein crystals in Adenovirus type 5-infected cells: requirements for intranuclear crystallogenesis, structural and functional analysis.

    Directory of Open Access Journals (Sweden)

    Laure Franqueville

    Full Text Available Intranuclear crystalline inclusions have been observed in the nucleus of epithelial cells infected with Adenovirus serotype 5 (Ad5 at late steps of the virus life cycle. Using immuno-electron microscopy and confocal microscopy of cells infected with various Ad5 recombinants modified in their penton base or fiber domains, we found that these inclusions represented crystals of penton capsomers, the heteromeric capsid protein formed of penton base and fiber subunits. The occurrence of protein crystals within the nucleus of infected cells required the integrity of the fiber knob and part of the shaft domain. In the knob domain, the region overlapping residues 489-492 in the FG loop was found to be essential for crystal formation. In the shaft, a large deletion of repeats 4 to 16 had no detrimental effect on crystal inclusions, whereas deletion of repeats 8 to 21 abolished crystal formation without altering the level of fiber protein expression. This suggested a crucial role of the five penultimate repeats in the crystallisation process. Chimeric pentons made of Ad5 penton base and fiber domains from different serotypes were analyzed with respect to crystal formation. No crystal was found when fiber consisted of shaft (S from Ad5 and knob (K from Ad3 (heterotypic S5-K3 fiber, but occurred with homotypic S3K3 fiber. However, less regular crystals were observed with homotypic S35-K35 fiber. TB5, a monoclonal antibody directed against the Ad5 fiber knob was found by immunofluorescence microscopy to react with high efficiency with the intranuclear protein crystals in situ. Data obtained with Ad fiber mutants indicated that the absence of crystalline inclusions correlated with a lower infectivity and/or lower yields of virus progeny, suggesting that the protein crystals might be involved in virion assembly. Thus, we propose that TB5 staining of Ad-infected 293 cells can be used as a prognostic assay for the viability and productivity of fiber-modified Ad5

  3. Intranuclear interactomic inhibition of NF-κB suppresses LPS-induced severe sepsis

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung-Dong [Translational Research Center for Protein Function Control, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of); Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of); Cheon, So Yeong [Department of Anesthesiology and Pain Medicine, Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul 120-752 (Korea, Republic of); Park, Tae-Yoon; Shin, Bo-Young [Translational Research Center for Protein Function Control, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of); Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of); Oh, Hyunju; Ghosh, Sankar [Department of Microbiology and Immunology, College of Physicians and Surgeons, Columbia University, New York, NY 10032 (United States); Koo, Bon-Nyeo, E-mail: koobn@yuhs.ac [Department of Anesthesiology and Pain Medicine, Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul 120-752 (Korea, Republic of); Lee, Sang-Kyou, E-mail: sjrlee@yonsei.ac.kr [Translational Research Center for Protein Function Control, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of); Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of)

    2015-08-28

    Suppression of nuclear factor-κB (NF-κB) activation, which is best known as a major regulator of innate and adaptive immune responses, is a potent strategy for the treatment of endotoxic sepsis. To inhibit NF-κB functions, we designed the intra-nuclear transducible form of transcription modulation domain (TMD) of RelA (p65), called nt-p65-TMD, which can be delivered effectively into the nucleus without influencing the cell viability, and work as interactomic inhibitors via disruption of the endogenous p65-mediated transcription complex. nt-p65-TMD effectively inhibited the secretion of pro-inflammatory cytokines, including TNF-α, IL-1β, or IL-6 from BV2 microglia cells stimulated by lipopolysaccharide (LPS). nt-p65-TMD did not inhibit tyrosine phosphorylation of signaling mediators such as ZAP-70, p38, JNK, or ERK involved in T cell activation, but was capable of suppressing the transcriptional activity of NF-κB without the functional effect on that of NFAT upon T-cell receptor (TCR) stimulation. The transduced nt-p65-TMD in T cell did not affect the expression of CD69, however significantly inhibited the secretion of T cell-specific cytokines such as IL-2, IFN-γ, IL-4, IL-17A, or IL-10. Systemic administration of nt-p65-TMD showed a significant therapeutic effect on LPS-induced sepsis model by inhibiting pro-inflammatory cytokines secretion. Therefore, nt-p65-TMD can be a novel therapeutics for the treatment of various inflammatory diseases, including sepsis, where a transcription factor has a key role in pathogenesis, and further allows us to discover new functions of p65 under normal physiological condition without genetic alteration. - Highlights: • The nt-p65-TMD is intra-nuclear interactomic inhibitor of endogenous p65. • The nt-p65-TMD effectively inhibited the secretion of pro-inflammatory cytokines. • The excellent therapeutic potential of nt-p65-TMD was confirmed in sepsis model.

  4. Intranuclear Inclusions in Renal Tubular Epithelium in Immunodeficient Mice Stain with Antibodies for Bovine Papillomavirus Type 1 L1 Protein

    Directory of Open Access Journals (Sweden)

    Elizabeth McInnes

    2015-06-01

    Full Text Available The kidneys from six immunodeficient mice examined by Cerberus Sciences and the Animal Resources Centre, displayed karyomegaly with pale eosinophilic, intranuclear inclusions upon histopathological examination. Electron microscopy performed on kidney tissue from 5/6 mice demonstrated margination of the chromatin in large nuclei. Laboratory tests were used to detect nucleic acid of papillomaviruses, polyomaviruses, circoviruses and anelloviruses (4/6 mice, a specific PCR was used to detect murine polyomavirus (1/6, and a panel of serological tests was used to detect seroconversion to major murine pathogens (1/6. All molecular and serological tests were negative. Immunohistochemistry using polyclonal anti-bovine papillomavirus type 1 (BPV-1 L1 antibody, Camvir monoclonal anti-papillomavirus antibody (directed against the seven amino acids GFGAMDF found in human papillomavirus (HPV 16 L1 protein, a commercially available mixture of two monoclonal antibodies, anti-BPV-1 L1/1H8 + Camvir antibodies, and a monoclonal anti-Hsc70 antibody revealed specific, positive staining of murine renal tubular epithelial intranuclear inclusions in 6/6 mice using the anti-BPV-1 L1 containing antibodies only. Methyl pyronin green, PAS and Feulgen histochemical reactions revealed that the intranuclear inclusions did not consist of RNA, DNA or carbohydrate. An immunohistochemical method now exists that can be used to confirm and evaluate suspected cases of murine inclusion body nephropathy.

  5. Degeneração oxychromatica ("inclusões intranucleares" na febre amarella

    Directory of Open Access Journals (Sweden)

    C. Magarinos Torres

    1931-05-01

    ção oxychromatica (figs. 37 e 40; são escassos e de caracterisação duvidosa em virtude da concomitancia de alterações necrobíoticas não específicas. 2- Durante a epidemia de febre amarella em 1928 no Rio de Janeiro, notamos differenças assaz pronunciadas entre as lesões hepaticas no homem e no M. rhesus. Taes differenças, existindo em material assaz homogeneo quanto ás amostras de virus em questão, nos levam a concluir que a capacidade de formar corpusculos intranucleares especificos, como tambem a já conhecida permanencia do virus no sangue e nos tecidos, depende, de modo evidente, da especie animal usada e não da propria amostra empregada, nem do numero de passagens que ella soffreu no macaco. Embora os doentes pertencessem a raças differentes (quadro VIII e embora, possivelmente diversas amostras de virus tenham sido nelles inoculadas, estamos autorisados a concluir que a amostra ou amostras que infectaram o homem na epidemia de 1928, no Rio de janeiro, possuem nelle uma fraca capacidade de determinar inclusões intranucleares. Ao contrario, a mesma amostra ou amostras são capazes de produzir no M. rhesus, logo na primeira passagem, inclusões intranucleares assaz abundantes. Outra diferença que notamos e attribuimos a especie animal empregada foi; as alterações hepaticas de natureza toxica e circulatoria (congestão, necrose e necrobiose da cellula hepatica são nitidamente mais intensas no homem que nos macacos injectados com as amostras brasileiras do virus da febre amarella isoladas durante a epidemia de 1928 no Rio de Janeiro. Conseguimos, no homem, evidencia de inclusões typicas na cellula hepatica, apenas em tres casos dentre dezesete examinados. Esse resultado, provavelmente, ainda não é definitivo, indicando, apenas a raridade extrema que os corpusculos podem apresentar nos casos de febre amarella que ordinariamente chegam á autopsia. Tambem não realisamos uma pesquiza exhaustiva dos corpusculos em outros orgãos além do figado. O caso no qual

  6. The CCFM Monte Carlo generator CASCADE 2.2.0

    CERN Document Server

    Jung, H; Deak, M; Grebenyuk, A; Hautmann, F; Hentschinski, M; Knutsson, A; Kraemer, M; Kutak, K; Lipatov, A; Zotov, N

    2010-01-01

    CASCADE is a full hadron level Monte Carlo event generator for ep, \\gamma p and p\\bar{p} and pp processes, which uses the CCFM evolution equation for the initial state cascade in a backward evolution approach supplemented with off - shell matrix elements for the hard scattering. A detailed program description is given, with emphasis on parameters the user wants to change and variables which completely specify the generated events.

  7. Cascade quantum teleportation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Nan-run; GONG Li-hua; LIU Ye

    2006-01-01

    In this letter a cascade quantum teleportation scheme is proposed. The proposed scheme needs less local quantum operations than those of quantum multi-teleportation. A quantum teleportation scheme based on entanglement swapping is presented and compared with the cascade quantum teleportation scheme. Those two schemes can effectively teleport quantum information and extend the distance of quantum communication.

  8. Cascade Lake: A Novel

    OpenAIRE

    Pack, Camille Marian

    2009-01-01

    Twenty-two-year-old Macy Oman narrates the book in retrospect from Cascade, Oregon, where she is visiting her mother. Macy's father moved with her to Portland shortly after the accidental death of her brother, Nick, seven years before the narration begins. Macy's mother stayed behind in Cascade. Thematically the work centers on the emotional repercussions of these losses. Macy's, and her older lover Jason's, involvement with Nick's death is unknown to everyone. Her guilt and her mother's perc...

  9. Familial frontotemporal dementia with neuronal intranuclear inclusions is not a polyglutamine expansion disease

    Directory of Open Access Journals (Sweden)

    Neal Scott J

    2006-08-01

    Full Text Available Abstract Background Many cases of frontotemporal dementia (FTD are familial, often with an autosomal dominant pattern of inheritance. Some are due to a mutation in the tau- encoding gene, on chromosome 17, and show an accumulation of abnormal tau in brain tissue (FTDP-17T. Most of the remaining familial cases do not exhibit tau pathology, but display neuropathology similar to patients with dementia and motor neuron disease, characterized by the presence of ubiquitin-immunoreactive (ub-ir, dystrophic neurites and neuronal cytoplasmic inclusions in the neocortex and hippocampus (FTLD-U. Recently, we described a subset of patients with familial FTD with autopsy-proven FTLD-U pathology and with the additional finding of ub-ir neuronal intranuclear inclusions (NII. NII are a characteristic feature of several other neurodegenerative conditions for which the genetic basis is abnormal expansion of a polyglutamine-encoding trinucleotide repeat region. The genetic basis of familial FTLD-U is currently not known, however the presence of NII suggests that a subset of cases may represent a polyglutamine expansion disease. Methods We studied DNA and post mortem brain tissue from 5 affected members of 4 different families with NII and one affected individual with familial FTLD-U without NII. Patient DNA was screened for CAA/CAG trinucleotide expansion in a set of candidate genes identified using a genome-wide computational approach. Genes containing CAA/CAG trinucleotide repeats encoding at least five glutamines were examined (n = 63, including the nine genes currently known to be associated with human disease. CAA/CAG tract sizes were compared with published normal values (where available and with those of healthy controls (n = 94. High-resolution agarose gel electrophoresis was used to measure allele size (number of CAA/CAG repeats. For any alleles estimated to be equal to or larger than the maximum measured in the control population, the CAA/CAG tract

  10. Electron - positron cascades in multiple-laser optical traps

    CERN Document Server

    Vranic, Marija; Fonseca, Ricardo A; Silva, Luis O

    2016-01-01

    We present an analytical and numerical study of multiple-laser QED cascades induced with linearly polarised laser pulses. We analyse different polarisation orientations and propose a configuration that maximises the cascade multiplicity and favours the laser absorption. We generalise the analytical estimate for the cascade growth rate previously calculated in the field of two colliding linearly polarised laser pulses and account for multiple laser interaction. The estimate is verified by a comprehensive numerical study of four-laser QED cascades across a range of different laser intensities with QED PIC module of OSIRIS. We show that by using four linearly polarised 30 fs laser pulses, one can convert more than 50 % of the total energy to gamma-rays already at laser intensity $I\\simeq10^{24}\\ \\mathrm{W/cm^2}$. In this configuration, the laser conversion efficiency is higher compared with the case with two colliding lasers.

  11. Cascade Organic Solar Cells

    KAUST Repository

    Schlenker, Cody W.

    2011-09-27

    We demonstrate planar organic solar cells consisting of a series of complementary donor materials with cascading exciton energies, incorporated in the following structure: glass/indium-tin-oxide/donor cascade/C 60/bathocuproine/Al. Using a tetracene layer grown in a descending energy cascade on 5,6-diphenyl-tetracene and capped with 5,6,11,12-tetraphenyl- tetracene, where the accessibility of the π-system in each material is expected to influence the rate of parasitic carrier leakage and charge recombination at the donor/acceptor interface, we observe an increase in open circuit voltage (Voc) of approximately 40% (corresponding to a change of +200 mV) compared to that of a single tetracene donor. Little change is observed in other parameters such as fill factor and short circuit current density (FF = 0.50 ± 0.02 and Jsc = 2.55 ± 0.23 mA/cm2) compared to those of the control tetracene-C60 solar cells (FF = 0.54 ± 0.02 and Jsc = 2.86 ± 0.23 mA/cm2). We demonstrate that this cascade architecture is effective in reducing losses due to polaron pair recombination at donor-acceptor interfaces, while enhancing spectral coverage, resulting in a substantial increase in the power conversion efficiency for cascade organic photovoltaic cells compared to tetracene and pentacene based devices with a single donor layer. © 2011 American Chemical Society.

  12. Cascaded Poisson processes

    Science.gov (United States)

    Matsuo, Kuniaki; Saleh, Bahaa E. A.; Teich, Malvin Carl

    1982-12-01

    We investigate the counting statistics for stationary and nonstationary cascaded Poisson processes. A simple equation is obtained for the variance-to-mean ratio in the limit of long counting times. Explicit expressions for the forward-recurrence and inter-event-time probability density functions are also obtained. The results are expected to be of use in a number of areas of physics.

  13. CSS - Cascading Style Sheets

    OpenAIRE

    Martinelli, Massimo

    2009-01-01

    Curso "CSS - Cascading Style Sheets" sobre programación web con CSS para el "Máster doble competencia en ciencias informáticas y ciencias sociales" ("Master double competence in computer science and social science"). Proyecto TEMPUS JEP – 26235-2005

  14. Production and Searches for Cascade Baryons with CLAS

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Elton

    2010-01-01

    We present the results of photoproduction cross sections of the ground state cascade $\\Xi^-$ and the first excited state $\\Xi^{*-}(1530)$ measured with the CLAS detector. The photoproduction of the cascade resonances has been investigated in the reactions $\\gamma p \\rightarrow K^+K^+(X)$ and $\\gamma p \\rightarrow K^+K^+\\pi^-(X)$. The differential and total cross sections of the $\\Xi^{-}$ were determined for photon beam energies from 2.75 to 4.75 GeV and are consistent with a production mechanism of $Y^* \\rightarrow K^+ \\Xi^-$ through a t-channel process. The cross-section of the $\\Xi^{*-}(1530)$ has been determined for photon beam energies from 3.35 to 4.75 GeV. The reaction $\\gamma p \\rightarrow K^+K^+ \\pi^- (\\Xi^0)$ has also been investigated to search for excited cascade resonances decaying to $\\pi^- \\Xi^0$. No significant signal of excited cascade states other than the well-known $\\Xi^{*-}(1530)$ is observed. We also present the latest results of a search for the $\\Phi^{--}$(1862) exotic pentaquark state in a photoproduction experiment on a deuterium target. A high-statistics sample of $\\pi^-\\Xi^-$ events have been collected and analyzed. A preliminary invariant mass spectrum of the $\\pi^-\\Xi^-$ system is presented, which is used to set upper limits on the photoproduction of the $\\Phi^{--}$ pentaquark state.

  15. Integrated Broadband Quantum Cascade Laser

    Science.gov (United States)

    Mansour, Kamjou (Inventor); Soibel, Alexander (Inventor)

    2016-01-01

    A broadband, integrated quantum cascade laser is disclosed, comprising ridge waveguide quantum cascade lasers formed by applying standard semiconductor process techniques to a monolithic structure of alternating layers of claddings and active region layers. The resulting ridge waveguide quantum cascade lasers may be individually controlled by independent voltage potentials, resulting in control of the overall spectrum of the integrated quantum cascade laser source. Other embodiments are described and claimed.

  16. Nuclear translocation and regulation of intranuclear distribution of cytoplasmic poly(A)-binding protein are distinct processes mediated by two Epstein Barr virus proteins.

    Science.gov (United States)

    Park, Richard; El-Guindy, Ayman; Heston, Lee; Lin, Su-Fang; Yu, Kuan-Ping; Nagy, Mate; Borah, Sumit; Delecluse, Henri-Jacques; Steitz, Joan; Miller, George

    2014-01-01

    Many viruses target cytoplasmic polyA binding protein (PABPC) to effect widespread inhibition of host gene expression, a process termed viral host-shutoff (vhs). During lytic replication of Epstein Barr Virus (EBV) we observed that PABPC was efficiently translocated from the cytoplasm to the nucleus. Translocated PABPC was diffusely distributed but was excluded from viral replication compartments. Vhs during EBV infection is regulated by the viral alkaline nuclease, BGLF5. Transfection of BGLF5 alone into BGLF5-KO cells or uninfected 293 cells promoted translocation of PAPBC that was distributed in clumps in the nucleus. ZEBRA, a viral bZIP protein, performs essential functions in the lytic program of EBV, including activation or repression of downstream viral genes. ZEBRA is also an essential replication protein that binds to viral oriLyt and interacts with other viral replication proteins. We report that ZEBRA also functions as a regulator of vhs. ZEBRA translocated PABPC to the nucleus, controlled the intranuclear distribution of PABPC, and caused global shutoff of host gene expression. Transfection of ZEBRA alone into 293 cells caused nuclear translocation of PABPC in the majority of cells in which ZEBRA was expressed. Co-transfection of ZEBRA with BGLF5 into BGLF5-KO cells or uninfected 293 cells rescued the diffuse intranuclear pattern of PABPC seen during lytic replication. ZEBRA mutants defective for DNA-binding were capable of regulating the intranuclear distribution of PABPC, and caused PABPC to co-localize with ZEBRA. One ZEBRA mutant, Z(S186E), was deficient in translocation yet was capable of altering the intranuclear distribution of PABPC. Therefore ZEBRA-mediated nuclear translocation of PABPC and regulation of intranuclear PABPC distribution are distinct events. Using a click chemistry-based assay for new protein synthesis, we show that ZEBRA and BGLF5 each function as viral host shutoff factors. PMID:24705134

  17. Nuclear translocation and regulation of intranuclear distribution of cytoplasmic poly(A-binding protein are distinct processes mediated by two Epstein Barr virus proteins.

    Directory of Open Access Journals (Sweden)

    Richard Park

    Full Text Available Many viruses target cytoplasmic polyA binding protein (PABPC to effect widespread inhibition of host gene expression, a process termed viral host-shutoff (vhs. During lytic replication of Epstein Barr Virus (EBV we observed that PABPC was efficiently translocated from the cytoplasm to the nucleus. Translocated PABPC was diffusely distributed but was excluded from viral replication compartments. Vhs during EBV infection is regulated by the viral alkaline nuclease, BGLF5. Transfection of BGLF5 alone into BGLF5-KO cells or uninfected 293 cells promoted translocation of PAPBC that was distributed in clumps in the nucleus. ZEBRA, a viral bZIP protein, performs essential functions in the lytic program of EBV, including activation or repression of downstream viral genes. ZEBRA is also an essential replication protein that binds to viral oriLyt and interacts with other viral replication proteins. We report that ZEBRA also functions as a regulator of vhs. ZEBRA translocated PABPC to the nucleus, controlled the intranuclear distribution of PABPC, and caused global shutoff of host gene expression. Transfection of ZEBRA alone into 293 cells caused nuclear translocation of PABPC in the majority of cells in which ZEBRA was expressed. Co-transfection of ZEBRA with BGLF5 into BGLF5-KO cells or uninfected 293 cells rescued the diffuse intranuclear pattern of PABPC seen during lytic replication. ZEBRA mutants defective for DNA-binding were capable of regulating the intranuclear distribution of PABPC, and caused PABPC to co-localize with ZEBRA. One ZEBRA mutant, Z(S186E, was deficient in translocation yet was capable of altering the intranuclear distribution of PABPC. Therefore ZEBRA-mediated nuclear translocation of PABPC and regulation of intranuclear PABPC distribution are distinct events. Using a click chemistry-based assay for new protein synthesis, we show that ZEBRA and BGLF5 each function as viral host shutoff factors.

  18. Intranuclear Delivery of a Novel Antibody-Derived Radiosensitizer Targeting the DNA-Dependent Protein Kinase Catalytic Subunit

    International Nuclear Information System (INIS)

    Purpose: To inhibit DNA double-strand break repair in tumor cells by delivery of a single-chain antibody variable region fragment (ScFv 18-2) to the cell nucleus. ScFv 18-2 binds to a regulatory region of the DNA-dependent protein kinase (DNA-PK), an essential enzyme in the nonhomologous end-joining pathway, and inhibits DNA end-joining in a cell-free system and when microinjected into single cells. Development as a radiosensitizer has been limited by the lack of a method for intranuclear delivery to target cells. We investigated a delivery method based on folate receptor–mediated endocytosis. Methods and Materials: A recombinant ScFv 18-2 derivative was conjugated to folate via a scissile disulfide linker. Folate-ScFv 18-2 was characterized for its ability to be internalized by tumor cells and to influence the behavior of ionizing radiation–induced repair foci. Radiosensitization was measured in a clonogenic survival assay. Survival curves were fitted to a linear-quadratic model, and between-group differences were evaluated by an F test. Sensitization ratios were determined based on mean inhibitory dose. Results: Human KB and NCI-H292 lung cancer cells treated with folate-conjugated ScFv 18-2 showed significant radiosensitization (p < 0.001). Sensitization enhancement ratios were 1.92 ± 0.42 for KB cells and 1.63 ± 0.13 for NCI-H292 cells. Studies suggest that treatment inhibits repair of radiation-induced DSBs, as evidenced by the persistence of γ-H2AX-stained foci and by inhibition of staining with anti-DNA-PKcs phosphoserine 2056. Conclusions: Folate-mediated endocytosis is an effective method for intranuclear delivery of an antibody-derived DNA repair inhibitor.

  19. A new cascadic multigrid

    Institute of Scientific and Technical Information of China (English)

    SHI; Zhongci

    2001-01-01

    [1]Bornemann, F., Deuflhard, P., The cascadic multigrid method for elliptic problems, Numer. Math., 996, 75: 35.[2]Bornemann, F., Deuflhard, P., The cascadic multigrid method, The Eighth International Conference on Domain Decomposition Methods for Partial Differential Equations (eds. Glowinski, R., Periaux, J., Shi, Z. et al.), New York: John Wiley and Sons, 997.[3]Bornemann, F., Krause, R., Classical and cascadic multigrid-methodogical comparison, Proceedings of the 9th International Conference on Domain Decomposition (eds. Bjorstad, P., Espedal, M., Keyes, D.), New York: John Wiley and Sons, 998.[4]Shaidurov, V., Some estimates of the rate of convergence for the cascadic conjugate gradient method, Comp. Math. Applic., 996, 3: 6.[5]Shi, Z., Xu, X., Cascadic multigrid method for the second order elliptic problem, East-West J. Numer. Math., 998, 6: 309.[6]Shi, Z., Xu, X., Cascadic multigrid for elliptic problems, East-West J. Numer. Math., 999, 7: 99.[7]Shi, Z., Xu, X., Cascadic multigrid method for the plate bending problem, East-West J. Numer. Math., 998, 6: 37.[8]Braess, D., Dahmen, W., A cascade multigrid algorithm for the Stokes equations, Number. Math., 999, 82: 79.[9]Shi, Z., Xu, X., Cascadic multigrid for parabolic problems, J. Comput. Math., 2000, 8: 450.[10]Ciarlet, P.,The Finite Element Method for Elliptic Problems, Amsterdam: North-Holland, 978.[11]Zienkiewicz, O. C., The Finite Element Method, 3rd. ed., London: McGraw-Hill, 977.[12]Powell, M. J. D., Sabin, M. A., Piecewise quadratic approximations on triangles, ACM Trans. Mat. Software, 977, 3: 36.[13]Xu, J., The auxiliary space method and optimal multigrid precondition techniques for unstructured grids, Computing, 996, 56: 25.[14]Bank, R., Dupont, T., An optimal order process for solving finite element equations, Math. Comput., 980, 36: 35.[15]Brenner, S., Convergence of nonconforming multigrid methods without full elliptic regularity, Math

  20. Quantum Cascade Detectors

    OpenAIRE

    Giorgetta, Fabrizio R.; Baumann, Esther; Graf, Marcel; Yang, Quankui; Manz, Christian; Köhler, Klaus; Beere, Harvey E.; Ritchie, David A.; Linfield, Edmund; Davies, Alexander G.; Fedoryshyn, Yuriy; Jackel, Heinz; Fischer, Milan; Faist, Jérôme; Hofstetter, Daniel

    2010-01-01

    This paper gives an overview on the design, fabrication, and characterization of quantum cascade detectors. They are tailorable infrared photodetectors based on intersubband transitions in semiconductor quantum wells that do not require an external bias voltage due to their asymmetric conduction band profile. They thus profit from favorable noise behavior, reduced thermal load, and simpler readout circuits. This was demonstrated at wavelengths from the near infrared at 2 μm to THz radiation a...

  1. Information cascade on networks

    Science.gov (United States)

    Hisakado, Masato; Mori, Shintaro

    2016-05-01

    In this paper, we discuss a voting model by considering three different kinds of networks: a random graph, the Barabási-Albert (BA) model, and a fitness model. A voting model represents the way in which public perceptions are conveyed to voters. Our voting model is constructed by using two types of voters-herders and independents-and two candidates. Independents conduct voting based on their fundamental values; on the other hand, herders base their voting on the number of previous votes. Hence, herders vote for the majority candidates and obtain information relating to previous votes from their networks. We discuss the difference between the phases on which the networks depend. Two kinds of phase transitions, an information cascade transition and a super-normal transition, were identified. The first of these is a transition between a state in which most voters make the correct choices and a state in which most of them are wrong. The second is a transition of convergence speed. The information cascade transition prevails when herder effects are stronger than the super-normal transition. In the BA and fitness models, the critical point of the information cascade transition is the same as that of the random network model. However, the critical point of the super-normal transition disappears when these two models are used. In conclusion, the influence of networks is shown to only affect the convergence speed and not the information cascade transition. We are therefore able to conclude that the influence of hubs on voters' perceptions is limited.

  2. Neutrino-Induced Cascades From GRBs With AMANDA-II

    CERN Document Server

    Hughey, B; Ahrens, J; Atlee, D W; Bahcall, J N; Bai, X; Baret, B; Bartelt, M; Bay, R; Barwick, S W; Beattie, K; Becka, T; Becker, K H; Becker, J K; Berghaus, P; Berley, D; Bernardini, E; Bertrand, D; Besson, D Z; Blaufuss, E; Boersma, D J; Bohm, C; Boser, S; Botner, O; Bouchta, A; Braun, J; Burgess, C; Burgess, T; Castermans, T; Chirkin, D; Clem, J; Conrad, J; Cooley, J; Cowen, D F; D'Agostino, M V; Davour, A; Day, C T; De Clercq, C; Desiati, P; De Young, T R; Dreyer, J; Duvoort, M R; Edwards, W R; Ehrlich, R; Ekstrom, P; Ellsworth, R W; Evenson, P A; Fazely, A R; Feser, T; Filimonov, K; Gaisser, T K; Gallagher, J; Ganugapati, R; Geenen, H; Gerhardt, L; Greene, M G; Grullon, S; Goldschmidt, A; Goodman, J; Gro, A; Gunasingha, R M; Hallgren, A; Halzen, F; Hanson, K; Hardtke, D; Hardtke, R; Harenberg, T; Hart, J E; Hauschildt, T; Hays, D; Heise, J; Helbing, K; Hellwig, M; Herquet, P; Hill, G C; Hodges, J; Hoffman, K D; Hoshina, K; Hubert, D; Hughey, B; Hulth, P O; Hultqvist, K; Hundertmark, S; Ishihara, A; Jacobsen, J; Japaridze, G S; Jones, A; Joseph, J M; Kampert, K H; Karle, A; Kawai, H; Kelley, J L; Kestel, M; Kitamura, N; Klein, S R; Klepser, S; Kohnen, G; Kolanoski, H; Köpke, L; Krasberg, M; Kühn, K; Kujawski, E; Landsman, H; Lang, R; Leich, H; Liubarsky, I; Lundberg, J; Madsen, J; Marciniewski, P; Mase, K; Matis, H S; McCauley, T; McParland, C P; Meli, A; Messarius, T; Mészáros, P; Minor, R H; Miocinovic, P; Miyamoto, H; Mokhtarani, A; Montaruli, T; Morey, A; Morse, R; Movit, S M; Munich, K; Nahnhauer, R; Nam, J W; Niessen, P; Nygren, D R; Ogelman, H; Olbrechts, P; Olivas, A; Patton, S; Peña-Garay, C; Perez de los Heros, C; Pieloth, D; Pohl, A C; Porrata, R; Pretz, J; Price, P B; Przybylski, G T; Rawlins, K; Razzaque, S; Refflinghaus, F; Resconi, E; Rhode, W; Ribordy, M; Richter, S; Rizzo, A; Robbins, S; Rott, C; Rutledge, D; Sander, H G; Schlenstedt, S; Schneider, D; Schwarz, R; Seckel, D; Seo, S H; Silvestri, A; Smith, A J; Solarz, M; Song, C; Sopher, J E; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Steffen, P; Stezelberger, T; Stokstad, R G; Stoufer, M; Stoyanov, S; Sulanke, K H; Sullivan, G W; Sumner, T J; Taboada, I; Tarasova, O; Tepe, A; Thollander, L; Tilav, S; Toale, P A; Turcan, D; van Eijndhoven, N; Vandenbroucke, J; Voigt, B; Wagner, W; Walck, C; Waldmann, H; Walter, M; Wang, Y R; Wendt, C; Wiebusch, C; Wikström, G; Williams, D; Wischnewski, R; Wissing, H; Woschnagg, K; Xu, X W; Yoshida, S; Yodh, G

    2005-01-01

    Using AMANDA-II we have performed a search for neutrino-induced cascades in coincidence with 73 bursts reported by BATSE in 2000. Background is greatly suppressed by the BATSE temporal constraint. No evidence of neutrinos was found. We set a limit on a WB-like spectrum, $A_{90}^{all flavors}$ = 9.5$\\times10^{-7}$ GeV cm$^{-2}$ s$^{-1}$ sr$^{-1}$. The determination of systematic uncertainties is in progress, and the limit will be somewhat weakened once these uncertainties are taken into account. We are also conducting a rolling time-window search for neutrino-induced cascades consistent with a GRB signal in 2001. The data set is searched for a statistically significant cluster of signal-like events within a 1 s or 100 s time window. The non-triggered search has the potential to discover phenomena, including gamma-ray dark choked bursts, which did not trigger gamma-ray detectors.

  3. Multiphase cascaded lattice Boltzmann method

    OpenAIRE

    Lycett-Brown, D.; Luo, K. H.

    2014-01-01

    To improve the stability of the lattice Boltzmann method (LBM) at high Reynolds number the cascaded LBM has recently been introduced. As in the multiple relaxation time (MRT) method the cascaded LBM introduces additional relaxation times into the collision operator, but does so in a co-moving reference frame. This has been shown to significantly increase stability at low viscosity in the single phase case. Here the cascaded LBM is further developed to include multiphase flow. For this the for...

  4. Cascade hydrodewaxing process

    Energy Technology Data Exchange (ETDEWEB)

    Yen, J.H.

    1986-07-08

    A cascade catalytic hydrodewaxing process is described comprising: (a) passing a hydrocarbon feedstock containing waxy components selected from a group of normal paraffins and slightly branched chain paraffins over a hydroisomerization catalyst comprising a crystalline silicate zeolite having the structure of ZSM-12 in admixture with a crystalline silicate zeolite having the structure of ZSM-23, the admixture having hydrogenation/dehydrogenation activity to hydroisomerize the feedstock; and (b) passing at least a majority of the normally liquid hydrocarbon recovered from step (a) over a dewaxing catalyst comprising a crystalline silicate zeolite having a structure of ZSM-5, the zeolite of step (b) having hydrogenation/-dehydrogenation activity to dewax the recovered hydrocarbon.

  5. Neuronal ubiquitinated intranuclear inclusions in familial and non-familial frontotemporal dementia of the motor neuron disease type associated with amyotrophic lateral sclerosis.

    Science.gov (United States)

    Bigio, Eileen H; Johnson, Nancy A; Rademaker, Alfred W; Fung, Bing B; Mesulam, M-Marsel; Siddique, Nailah; Dellefave, Lisa; Caliendo, Janice; Freeman, Stefanie; Siddique, Teepu

    2004-08-01

    Ubiquitinated cytoplasmic inclusions (Ub-CIs) in superficial frontal cortex and dentate gyrus neurons are the hallmark of frontotemporal degeneration of the motor neuron disease-type (FTD-MND-type). To date, 2 reports have described intranuclear ubiquitinated inclusions (Ub-INIs) in 9 cases of familial FTD-MND-type (without clinical or pathologic motor neuron disease, MND). In the current study we found an additional 11 cases with Ub-INIs. We have identified for the first time among these cases 2 with a negative family history and 3 that have concomitant amyotrophic lateral sclerosis (ALS). The results of the present study i) confirm a previous report of significantly lower average brain weight and longer duration in cases with Ub-INIs, ii) reveal significantly greater striatal neuronal loss and gliosis in cases with intranuclear inclusions, and iii) demonstrate that intranuclear inclusions correlate with cytoplasmic inclusions and dystrophic neurites in frontal cortex and striatum but not in dentate gyrus. In addition, the current study confirms that Ub-INIs are found in familial FTD-MND-type, but also extends the presence of Ub-INIs to familial FTD-MND (with concomitant ALS), and probably also to non-familial FTD-MND-type. PMID:15330335

  6. Neuronal ubiquitinated intranuclear inclusions in familial and non-familial frontotemporal dementia of the motor neuron disease type associated with amyotrophic lateral sclerosis.

    Science.gov (United States)

    Bigio, Eileen H; Johnson, Nancy A; Rademaker, Alfred W; Fung, Bing B; Mesulam, M-Marsel; Siddique, Nailah; Dellefave, Lisa; Caliendo, Janice; Freeman, Stefanie; Siddique, Teepu

    2004-08-01

    Ubiquitinated cytoplasmic inclusions (Ub-CIs) in superficial frontal cortex and dentate gyrus neurons are the hallmark of frontotemporal degeneration of the motor neuron disease-type (FTD-MND-type). To date, 2 reports have described intranuclear ubiquitinated inclusions (Ub-INIs) in 9 cases of familial FTD-MND-type (without clinical or pathologic motor neuron disease, MND). In the current study we found an additional 11 cases with Ub-INIs. We have identified for the first time among these cases 2 with a negative family history and 3 that have concomitant amyotrophic lateral sclerosis (ALS). The results of the present study i) confirm a previous report of significantly lower average brain weight and longer duration in cases with Ub-INIs, ii) reveal significantly greater striatal neuronal loss and gliosis in cases with intranuclear inclusions, and iii) demonstrate that intranuclear inclusions correlate with cytoplasmic inclusions and dystrophic neurites in frontal cortex and striatum but not in dentate gyrus. In addition, the current study confirms that Ub-INIs are found in familial FTD-MND-type, but also extends the presence of Ub-INIs to familial FTD-MND (with concomitant ALS), and probably also to non-familial FTD-MND-type.

  7. Energy Cascades in MHD

    Science.gov (United States)

    Alexakis, A.

    2009-04-01

    Most astrophysical and planetary systems e.g., solar convection and stellar winds, are in a turbulent state and coupled to magnetic fields. Understanding and quantifying the statistical properties of magneto-hydro-dynamic (MHD) turbulence is crucial to explain the involved physical processes. Although the phenomenological theory of hydro-dynamic (HD) turbulence has been verified up to small corrections, a similar statement cannot be made for MHD turbulence. Since the phenomenological description of Hydrodynamic turbulence by Kolmogorov in 1941 there have been many attempts to derive a similar description for turbulence in conducting fluids (i.e Magneto-Hydrodynamic turbulence). However such a description is going to be based inevitably on strong assumptions (typically borrowed from hydrodynamics) that do not however necessarily apply to the MHD case. In this talk I will discuss some of the properties and differences of the energy and helicity cascades in turbulent MHD and HD flows. The investigation is going to be based on the analysis of direct numerical simulations. The cascades in MHD turbulence appear to be a more non-local process (in scale space) than in Hydrodynamics. Some implications of these results to turbulent modeling will be discussed

  8. Do nuclear envelope and intranuclear proteins reorganize during mitosis to form an elastic, hydrogel-like spindle matrix?

    Science.gov (United States)

    Johansen, Kristen M; Forer, Arthur; Yao, Changfu; Girton, Jack; Johansen, Jørgen

    2011-04-01

    The idea of a spindle matrix has long been proposed in order to account for poorly understood features of mitosis. However, its molecular nature and structural composition have remained elusive. Here, we propose that the spindle matrix may be constituted by mainly nuclear-derived proteins that reorganize during the cell cycle to form an elastic gel-like matrix. We discuss this hypothesis in the context of recent observations from phylogenetically diverse organisms that nuclear envelope and intranuclear proteins form a highly dynamic and malleable structure that contributes to mitotic spindle function. We suggest that the viscoelastic properties of such a matrix may constrain spindle length while at the same time facilitating microtubule growth and dynamics as well as chromosome movement. A corollary to this hypothesis is that a key determinant of spindle size may be the amount of nuclear proteins available to form the spindle matrix. Such a matrix could also serve as a spatial regulator of spindle assembly checkpoint proteins during open and semi-open mitosis. PMID:21274615

  9. Atypical sporadic CJD-MM phenotype with white matter kuru plaques associated with intranuclear inclusion body and argyrophilic grain disease.

    Science.gov (United States)

    Berghoff, Anna S; Trummert, Anita; Unterberger, Ursula; Ströbel, Thomas; Hortobágyi, Tibor; Kovacs, Gabor G

    2015-08-01

    We describe an atypical neuropathological phenotype of sporadic Creutzfeldt-Jakob disease in a 76-year-old man. The clinical symptoms were characterized by progressive dementia, gait ataxia, rigidity and urinary incontinence. The disease duration was 6 weeks. MRI did not show prominent atrophy or hyperintensities in cortical areas, striatum or thalamus. Biomarker examination of the cerebrospinal fluid deviated from that seen in pure Alzheimer's disease. Triphasic waves in the EEG were detected only later in the disease course, while 14-3-3 assay was positive. PRNP genotyping revealed methionine homozygosity (MM) at codon 129. Neuropathology showed classical CJD changes corresponding to the MM type 1 cases. However, a striking feature was the presence of abundant kuru-type plaques in the white matter. This rare morphology was associated with neuropathological signs of intranuclear inclusion body disease and advanced stage of argyrophilic grain disease. These alterations did not show correlation with each other, thus seemed to develop independently. This case further highlights the complexity of neuropathological alterations in the ageing brain.

  10. Atypical sporadic CJD-MM phenotype with white matter kuru plaques associated with intranuclear inclusion body and argyrophilic grain disease.

    Science.gov (United States)

    Berghoff, Anna S; Trummert, Anita; Unterberger, Ursula; Ströbel, Thomas; Hortobágyi, Tibor; Kovacs, Gabor G

    2015-08-01

    We describe an atypical neuropathological phenotype of sporadic Creutzfeldt-Jakob disease in a 76-year-old man. The clinical symptoms were characterized by progressive dementia, gait ataxia, rigidity and urinary incontinence. The disease duration was 6 weeks. MRI did not show prominent atrophy or hyperintensities in cortical areas, striatum or thalamus. Biomarker examination of the cerebrospinal fluid deviated from that seen in pure Alzheimer's disease. Triphasic waves in the EEG were detected only later in the disease course, while 14-3-3 assay was positive. PRNP genotyping revealed methionine homozygosity (MM) at codon 129. Neuropathology showed classical CJD changes corresponding to the MM type 1 cases. However, a striking feature was the presence of abundant kuru-type plaques in the white matter. This rare morphology was associated with neuropathological signs of intranuclear inclusion body disease and advanced stage of argyrophilic grain disease. These alterations did not show correlation with each other, thus seemed to develop independently. This case further highlights the complexity of neuropathological alterations in the ageing brain. PMID:25783686

  11. Linear models of activation cascades: analytical solutions and coarse-graining of delayed signal transduction.

    Science.gov (United States)

    Beguerisse-Díaz, Mariano; Desikan, Radhika; Barahona, Mauricio

    2016-08-01

    Cellular signal transduction usually involves activation cascades, the sequential activation of a series of proteins following the reception of an input signal. Here, we study the classic model of weakly activated cascades and obtain analytical solutions for a variety of inputs. We show that in the special but important case of optimal gain cascades (i.e. when the deactivation rates are identical) the downstream output of the cascade can be represented exactly as a lumped nonlinear module containing an incomplete gamma function with real parameters that depend on the rates and length of the cascade, as well as parameters of the input signal. The expressions obtained can be applied to the non-identical case when the deactivation rates are random to capture the variability in the cascade outputs. We also show that cascades can be rearranged so that blocks with similar rates can be lumped and represented through our nonlinear modules. Our results can be used both to represent cascades in computational models of differential equations and to fit data efficiently, by reducing the number of equations and parameters involved. In particular, the length of the cascade appears as a real-valued parameter and can thus be fitted in the same manner as Hill coefficients. Finally, we show how the obtained nonlinear modules can be used instead of delay differential equations to model delays in signal transduction.

  12. Linear models of activation cascades: analytical solutions and coarse-graining of delayed signal transduction

    Science.gov (United States)

    Desikan, Radhika

    2016-01-01

    Cellular signal transduction usually involves activation cascades, the sequential activation of a series of proteins following the reception of an input signal. Here, we study the classic model of weakly activated cascades and obtain analytical solutions for a variety of inputs. We show that in the special but important case of optimal gain cascades (i.e. when the deactivation rates are identical) the downstream output of the cascade can be represented exactly as a lumped nonlinear module containing an incomplete gamma function with real parameters that depend on the rates and length of the cascade, as well as parameters of the input signal. The expressions obtained can be applied to the non-identical case when the deactivation rates are random to capture the variability in the cascade outputs. We also show that cascades can be rearranged so that blocks with similar rates can be lumped and represented through our nonlinear modules. Our results can be used both to represent cascades in computational models of differential equations and to fit data efficiently, by reducing the number of equations and parameters involved. In particular, the length of the cascade appears as a real-valued parameter and can thus be fitted in the same manner as Hill coefficients. Finally, we show how the obtained nonlinear modules can be used instead of delay differential equations to model delays in signal transduction. PMID:27581482

  13. Cascade Error Projection Learning Algorithm

    Science.gov (United States)

    Duong, T. A.; Stubberud, A. R.; Daud, T.

    1995-01-01

    A detailed mathematical analysis is presented for a new learning algorithm termed cascade error projection (CEP) and a general learning frame work. This frame work can be used to obtain the cascade correlation learning algorithm by choosing a particular set of parameters.

  14. Cascade Distillation System Development

    Science.gov (United States)

    Callahan, Michael R.; Sargushingh, Miriam; Shull, Sarah

    2014-01-01

    NASA's Advanced Exploration Systems (AES) Life Support System (LSS) Project is chartered with de-veloping advanced life support systems that will ena-ble NASA human exploration beyond low Earth orbit (LEO). The goal of AES is to increase the affordabil-ity of long-duration life support missions, and to re-duce the risk associated with integrating and infusing new enabling technologies required to ensure mission success. Because of the robust nature of distillation systems, the AES LSS Project is pursuing develop-ment of the Cascade Distillation Subsystem (CDS) as part of its technology portfolio. Currently, the system is being developed into a flight forward Generation 2.0 design.

  15. Interband cascade lasers

    Science.gov (United States)

    Vurgaftman, I.; Weih, R.; Kamp, M.; Meyer, J. R.; Canedy, C. L.; Kim, C. S.; Kim, M.; Bewley, W. W.; Merritt, C. D.; Abell, J.; Höfling, S.

    2015-04-01

    We review the current status of interband cascade lasers (ICLs) emitting in the midwave infrared (IR). The ICL may be considered the hybrid of a conventional diode laser that generates photons via electron-hole recombination, and an intersubband-based quantum cascade laser (QCL) that stacks multiple stages for enhanced current efficiency. Following a brief historical overview, we discuss theoretical aspects of the active region and core designs, growth by molecular beam epitaxy, and the processing of broad-area, narrow-ridge, and distributed feedback (DFB) devices. We then review the experimental performance of pulsed broad area ICLs, as well as the continuous-wave (cw) characteristics of narrow ridges having good beam quality and DFBs producing output in a single spectral mode. Because the threshold drive powers are far lower than those of QCLs throughout the λ = 3-6 µm spectral band, ICLs are increasingly viewed as the laser of choice for mid-IR laser spectroscopy applications that do not require high output power but need to be hand-portable and/or battery operated. Demonstrated ICL performance characteristics to date include threshold current densities as low as 106 A cm-2 at room temperature (RT), cw threshold drive powers as low as 29 mW at RT, maximum cw operating temperatures as high as 118 °C, maximum cw output powers exceeding 400 mW at RT, maximum cw wallplug efficiencies as high as 18% at RT, maximum cw single-mode output powers as high as 55 mW at RT, and single-mode output at λ = 5.2 µm with a cw drive power of only 138 mW at RT.

  16. Interband cascade lasers

    International Nuclear Information System (INIS)

    We review the current status of interband cascade lasers (ICLs) emitting in the midwave infrared (IR). The ICL may be considered the hybrid of a conventional diode laser that generates photons via electron–hole recombination, and an intersubband-based quantum cascade laser (QCL) that stacks multiple stages for enhanced current efficiency. Following a brief historical overview, we discuss theoretical aspects of the active region and core designs, growth by molecular beam epitaxy, and the processing of broad-area, narrow-ridge, and distributed feedback (DFB) devices. We then review the experimental performance of pulsed broad area ICLs, as well as the continuous-wave (cw) characteristics of narrow ridges having good beam quality and DFBs producing output in a single spectral mode. Because the threshold drive powers are far lower than those of QCLs throughout the λ = 3–6 µm spectral band, ICLs are increasingly viewed as the laser of choice for mid-IR laser spectroscopy applications that do not require high output power but need to be hand-portable and/or battery operated. Demonstrated ICL performance characteristics to date include threshold current densities as low as 106 A cm−2 at room temperature (RT), cw threshold drive powers as low as 29 mW at RT, maximum cw operating temperatures as high as 118 °C, maximum cw output powers exceeding 400 mW at RT, maximum cw wallplug efficiencies as high as 18% at RT, maximum cw single-mode output powers as high as 55 mW at RT, and single-mode output at λ = 5.2 µm with a cw drive power of only 138 mW at RT. (topical review)

  17. An automated Monte-Carlo based method for the calculation of cascade summing factors

    Science.gov (United States)

    Jackson, M. J.; Britton, R.; Davies, A. V.; McLarty, J. L.; Goodwin, M.

    2016-10-01

    A versatile method has been developed to calculate cascade summing factors for use in quantitative gamma-spectrometry analysis procedures. The proposed method is based solely on Evaluated Nuclear Structure Data File (ENSDF) nuclear data, an X-ray energy library, and accurate efficiency characterisations for single detector counting geometries. The algorithm, which accounts for γ-γ, γ-X, γ-511 and γ-e- coincidences, can be applied to any design of gamma spectrometer and can be expanded to incorporate any number of nuclides. Efficiency characterisations can be derived from measured or mathematically modelled functions, and can accommodate both point and volumetric source types. The calculated results are shown to be consistent with an industry standard gamma-spectrometry software package. Additional benefits including calculation of cascade summing factors for all gamma and X-ray emissions, not just the major emission lines, are also highlighted.

  18. Design of a microfluidic device to quantify dynamic intra-nuclear deformation during cell migration through confining environments.

    Science.gov (United States)

    Davidson, Patricia M; Sliz, Josiah; Isermann, Philipp; Denais, Celine; Lammerding, Jan

    2015-12-01

    The ability of cells to migrate through tissues and interstitial spaces is an essential factor during development and tissue homeostasis, immune cell mobility, and in various human diseases. Deformation of the nucleus and its associated lamina during 3-D migration is gathering increasing interest in the context of cancer metastasis, with the underlying hypothesis that a softer nucleus, resulting from reduced levels of lamin A/C, may aid tumour spreading. However, current methods to study the migration of cells in confining three dimensional (3-D) environments are limited by their imprecise control over the confinement, physiological relevance, and/or compatibility with high resolution imaging techniques. We describe the design of a polydimethylsiloxane (PDMS) microfluidic device composed of channels with precisely-defined constrictions mimicking physiological environments that enable high resolution imaging of live and fixed cells. The device promotes easy cell loading and rapid, yet long-lasting (>24 hours) chemotactic gradient formation without the need for continuous perfusion. Using this device, we obtained detailed, quantitative measurements of dynamic nuclear deformation as cells migrate through tight spaces, revealing distinct phases of nuclear translocation through the constriction, buckling of the nuclear lamina, and severe intranuclear strain. Furthermore, we found that lamin A/C-deficient cells exhibited increased and more plastic nuclear deformations compared to wild-type cells but only minimal changes in nuclear volume, implying that low lamin A/C levels facilitate migration through constrictions by increasing nuclear deformability rather than compressibility. The integration of our migration devices with high resolution time-lapse imaging provides a powerful new approach to study intracellular mechanics and dynamics in a variety of physiologically-relevant applications, ranging from cancer cell invasion to immune cell recruitment. PMID:26549481

  19. Cascade Mountain Range in Oregon

    Science.gov (United States)

    Sherrod, David R.

    2016-01-01

    The Cascade mountain system extends from northern California to central British Columbia. In Oregon, it comprises the Cascade Range, which is 260 miles long and, at greatest breadth, 90 miles wide (fig. 1). Oregon’s Cascade Range covers roughly 17,000 square miles, or about 17 percent of the state, an area larger than each of the smallest nine of the fifty United States. The range is bounded on the east by U.S. Highways 97 and 197. On the west it reaches nearly to Interstate 5, forming the eastern margin of the Willamette Valley and, farther south, abutting the Coast Ranges. 

  20. Cascade redox flow battery systems

    Energy Technology Data Exchange (ETDEWEB)

    Horne, Craig R.; Kinoshita, Kim; Hickey, Darren B.; Sha, Jay E.; Bose, Deepak

    2014-07-22

    A reduction/oxidation ("redox") flow battery system includes a series of electrochemical cells arranged in a cascade, whereby liquid electrolyte reacts in a first electrochemical cell (or group of cells) before being directed into a second cell (or group of cells) where it reacts before being directed to subsequent cells. The cascade includes 2 to n stages, each stage having one or more electrochemical cells. During a charge reaction, electrolyte entering a first stage will have a lower state-of-charge than electrolyte entering the nth stage. In some embodiments, cell components and/or characteristics may be configured based on a state-of-charge of electrolytes expected at each cascade stage. Such engineered cascades provide redox flow battery systems with higher energy efficiency over a broader range of current density than prior art arrangements.

  1. Cascading Gravity is Ghost Free

    CERN Document Server

    de Rham, Claudia; Tolley, Andrew J

    2010-01-01

    We perform a full perturbative stability analysis of the 6D cascading gravity model in the presence of 3-brane tension. We demonstrate that for sufficiently large tension on the (flat) 3-brane, there are no ghosts at the perturbative level, consistent with results that had previously only been obtained in a specific 5D decoupling limit. These results establish the cascading gravity framework as a consistent infrared modification of gravity.

  2. Interband Cascade Photovoltaic Cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui Q. [Univ. of Oklahoma, Norman, OK (United States); Santos, Michael B. [Univ. of Oklahoma, Norman, OK (United States); Johnson, Matthew B. [Univ. of Oklahoma, Norman, OK (United States)

    2014-09-24

    In this project, we are performing basic and applied research to systematically investigate our newly proposed interband cascade (IC) photovoltaic (PV) cells [1]. These cells follow from the great success of infrared IC lasers [2-3] that pioneered the use of quantum-engineered IC structures. This quantum-engineered approach will enable PV cells to efficiently convert infrared radiation from the sun or other heat source, to electricity. Such cells will have important applications for more efficient use of solar energy, waste-heat recovery, and power beaming in combination with mid-infrared lasers. The objectives of our investigations are to: achieve extensive understanding of the fundamental aspects of the proposed PV structures, develop the necessary knowledge for making such IC PV cells, and demonstrate prototype working PV cells. This research will focus on IC PV structures and their segments for utilizing infrared radiation with wavelengths from 2 to 5 μm, a range well suited for emission by heat sources (1,000-2,000 K) that are widely available from combustion systems. The long-term goal of this project is to push PV technology to longer wavelengths, allowing for relatively low-temperature thermal sources. Our investigations address material quality, electrical and optical properties, and their interplay for the different regions of an IC PV structure. The tasks involve: design, modeling and optimization of IC PV structures, molecular beam epitaxial growth of PV structures and relevant segments, material characterization, prototype device fabrication and testing. At the end of this program, we expect to generate new cutting-edge knowledge in the design and understanding of quantum-engineered semiconductor structures, and demonstrate the concepts for IC PV devices with high conversion efficiencies.

  3. Communication Scheme via Cascade Chaotic Systems

    Institute of Scientific and Technical Information of China (English)

    HUA Chang-Chun; GUAN Xin-Ping

    2004-01-01

    @@ A new chaotic communication scheme is constructed. Different from the existing literature, cascade chaotic systems are employed. Two cascade modes are considered. First, we investigate the input to state cascade mode;cascade systems between different kinds of chaotic systems are considered. Then the parameter cascade case of chaotic system is studied. Under the different cases, the corresponding receivers are designed, which can succeed in recovering the former emitted signal. Simulations are performed to verify the validity of the proposed main results.

  4. A Cascading Failure Model by Quantifying Interactions

    OpenAIRE

    Qi, Junjian; Mei, Shengwei

    2013-01-01

    Cascading failures triggered by trivial initial events are encountered in many complex systems. It is the interaction and coupling between components of the system that causes cascading failures. We propose a simple model to simulate cascading failure by using the matrix that determines how components interact with each other. A careful comparison is made between the original cascades and the simulated cascades by the proposed model. It is seen that the model can capture general features of t...

  5. Measuring the Luminosity of a gamma gamma Collider with gamma gamma -> l+ l- gamma Events

    OpenAIRE

    Makarenko, V.; Moenig, K.; Shishkina, T.

    2003-01-01

    The process gamma gamma -> l+ l- is highly suppressed when the total angular momentum of the two colliding photons is zero so that it cannot be used for luminosity determination. This configuration, however is needed for Higgs production at a photon collider. It will be shown that the process gamma gamma -> l+ l- gamma can be used in this case to measure the luminosity of a collider with a precision that is good enough not to limit the error on the partial decay width Gamma(H -> gamma gamma).

  6. Hyperinvasive Meningococci Induce Intra-nuclear Cleavage of the NF-κB Protein p65/RelA by Meningococcal IgA Protease.

    Directory of Open Access Journals (Sweden)

    Anissa Besbes

    2015-08-01

    Full Text Available Differential modulation of NF-κB during meningococcal infection is critical in innate immune response to meningococcal disease. Non-invasive isolates of Neisseria meningitidis provoke a sustained NF-κB activation in epithelial cells. However, the hyperinvasive isolates of the ST-11 clonal complex (ST-11 only induce an early NF-κB activation followed by a sustained activation of JNK and apoptosis. We show that this temporal activation of NF-κB was caused by specific cleavage at the C-terminal region of NF-κB p65/RelA component within the nucleus of infected cells. This cleavage was mediated by the secreted 150 kDa meningococcal ST-11 IgA protease carrying nuclear localisation signals (NLS in its α-peptide moiety that allowed efficient intra-nuclear transport. In a collection of non-ST-11 healthy carriage isolates lacking NLS in the α-peptide, secreted IgA protease was devoid of intra-nuclear transport. This part of iga polymorphism allows non-invasive isolates lacking NLS, unlike hyperinvasive ST-11 isolates of N. meningitides habouring NLS in their α-peptide, to be carried asymptomatically in the human nasopharynx through selective eradication of their ability to induce apoptosis in infected epithelial cells.

  7. Hyperinvasive Meningococci Induce Intra-nuclear Cleavage of the NF-κB Protein p65/RelA by Meningococcal IgA Protease.

    Science.gov (United States)

    Besbes, Anissa; Le Goff, Salomé; Antunes, Ana; Terrade, Aude; Hong, Eva; Giorgini, Dario; Taha, Muhamed-Kheir; Deghmane, Ala-Eddine

    2015-08-01

    Differential modulation of NF-κB during meningococcal infection is critical in innate immune response to meningococcal disease. Non-invasive isolates of Neisseria meningitidis provoke a sustained NF-κB activation in epithelial cells. However, the hyperinvasive isolates of the ST-11 clonal complex (ST-11) only induce an early NF-κB activation followed by a sustained activation of JNK and apoptosis. We show that this temporal activation of NF-κB was caused by specific cleavage at the C-terminal region of NF-κB p65/RelA component within the nucleus of infected cells. This cleavage was mediated by the secreted 150 kDa meningococcal ST-11 IgA protease carrying nuclear localisation signals (NLS) in its α-peptide moiety that allowed efficient intra-nuclear transport. In a collection of non-ST-11 healthy carriage isolates lacking NLS in the α-peptide, secreted IgA protease was devoid of intra-nuclear transport. This part of iga polymorphism allows non-invasive isolates lacking NLS, unlike hyperinvasive ST-11 isolates of N. meningitides habouring NLS in their α-peptide, to be carried asymptomatically in the human nasopharynx through selective eradication of their ability to induce apoptosis in infected epithelial cells. PMID:26241037

  8. Economical cascadic multigrid method (ECMG)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, an economical cascadic multigrid method is proposed. Compared with the usual cascadic multigrid method developed by Bornemann and Deuflhard, the new one requires less iterations on each level, especially on the coarser grids. Many operations can be saved in the new cascadic multigrid algorithms. The main ingredient is the control of the iteration numbers on the each level to preserve the accuracy without over iterations. The theoretical justification is based on the observations that the error reduction rate of an iteration scheme in terms of the smoothing property is no longer accurate while the iteration number is big enough. A new formulae of the error reduction rate is employed in our new algorithm. Numerical experiments are reported to support our theory.

  9. Rescuing Ecosystems from Extinction Cascades

    Science.gov (United States)

    Sahasrabudhe, Sagar; Motter, Adilson

    2010-03-01

    Food web perturbations stemming from climate change, overexploitation, invasive species, and natural disasters often cause an initial loss of species that results in a cascade of secondary extinctions. Using a predictive modeling framework, here we will present a systematic network-based approach to reduce the number of secondary extinctions. We will show that the extinction of one species can often be compensated by the concurrent removal of a second specific species, which is a counter-intuitive effect not previously tested in complex food webs. These compensatory perturbations frequently involve long-range interactions that are not a priori evident from local predator-prey relationships. Strikingly, in numerous cases even the early removal of a species that would eventually be extinct by the cascade is found to significantly reduce the number of cascading extinctions. Other nondestructive interventions based on partial removals and growth suppression and/or mortality increase are shown to sometimes prevent all secondary extinctions.

  10. Precision measurements of gamma-ray intensities

    International Nuclear Information System (INIS)

    To determine relative intensities of gamma rays in the region of 280 to 2750 keV, Ge(Li) detectors were calibrated with standard sources and cascade gamma-ray sources. Decay rates of the standard sources were determined by means of the 4πβ-γ or 4πX-γ coincidence method. Experimental conditions were improved and spectra were carefully analyzed. Relative gamma-ray intensities of 56Co, 88Y, sup(110m)Ag, 133Ba, 134Cs, 152Eu, 154Eu, 192Ir and 207Bi were determined within the accuracy of about 0.5% for strong gamma rays. Intensities per decays were obtained from the relative intensities for most of the nuclides. (author)

  11. Characteristics for two kinds of cascading events

    Science.gov (United States)

    Zou, Sheng-Rong; Gu, Ai-Hua; Liu, Ai-Fen; Xu, Xiu-Lian; Wang, Jian; He, Da-Ren

    2011-04-01

    Avalanche or cascade failure is ubiquitous. We first classify the cascading phenomena into two categories: the cascading disasters which result in large-scale functional failures and the cascading events that do not lead to disasters. We elucidate that two important factors, the increasing amount of events and the acceleration of event frequency, can induce the crossover from the cascading phenomenon to the cascading disaster. Through a simplified sandpile model and a heuristic logistic map, we demonstrate that the dependence of the event number on the observation time behaves as a power-law and as an exponential for these two different cascading events, respectively. The analytic derivations are found to be consistent with several empirical observations. Our present findings contribute to the understanding of the transition between different cascading events, providing a basis for the further understanding of the transitions among more general critical events.

  12. Cascade Support Vector Machines with Dimensionality Reduction

    Directory of Open Access Journals (Sweden)

    Oliver Kramer

    2015-01-01

    Full Text Available Cascade support vector machines have been introduced as extension of classic support vector machines that allow a fast training on large data sets. In this work, we combine cascade support vector machines with dimensionality reduction based preprocessing. The cascade principle allows fast learning based on the division of the training set into subsets and the union of cascade learning results based on support vectors in each cascade level. The combination with dimensionality reduction as preprocessing results in a significant speedup, often without loss of classifier accuracies, while considering the high-dimensional pendants of the low-dimensional support vectors in each new cascade level. We analyze and compare various instantiations of dimensionality reduction preprocessing and cascade SVMs with principal component analysis, locally linear embedding, and isometric mapping. The experimental analysis on various artificial and real-world benchmark problems includes various cascade specific parameters like intermediate training set sizes and dimensionalities.

  13. Unsteady transonic flow in cascades

    Science.gov (United States)

    Surampudi, S. P.; Adamczyk, J. J.

    1984-01-01

    There is a need for methods to predict the unsteady air loads associated with flutter of turbomachinery blading at transonic speeds. The results of such an analysis in which the steady relative flow approaching a cascade of thin airfoils is assumed to be transonic, irrotational, and isentropic is presented. The blades in the cascade are allowed to undergo a small amplitude harmonic oscillation which generates a small unsteady flow superimposed on the existing steady flow. The blades are assumed to oscillate with a prescribed motion of constant amplitude and interblade phase angle. The equations of motion are obtained by linearizing about a uniform flow the inviscid nonheat conducting continuity and momentum equations. The resulting equations are solved by employing the Weiner Hopf technique. The solution yields the unsteady aerodynamic forces acting on the cascade at Mach number equal to 1. Making use of an unsteady transonic similarity law, these results are compared with the results obtained from linear unsteady subsonic and supersonic cascade theories. A parametric study is conducted to find the effects of reduced frequency, solidity, stagger angle, and position of pitching axis on the flutter.

  14. Applications of cascade multilevel inverters

    Institute of Scientific and Technical Information of China (English)

    彭方正; 钱照明

    2003-01-01

    Cascade multilevel inverters have been developed for electric utility applications. A cascade M-level inverter consists of (M-1)/2 H-bridges in which each bridge's dc voltage is supported by its own de ca-pacitor. The new inverter can : ( 1 ) generate almost sinusoidal waveform voltage while only switching one timeper fundamental cycle ; (2) dispense with multi-pulse inverters' transformers used in conventional utility in-terfaces and static var compensators; (3) enables direct parallel or series transformer-less connection to medium- and high-voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi-pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features,feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical,simulated, and experimental results demonstrated the superiority of the new inverters.

  15. Applications of cascade multilevel inverters

    Institute of Scientific and Technical Information of China (English)

    彭方正; 钱照明

    2003-01-01

    Cascade multilevel inverters have been developed for electric utility applications. A cascade M-level inverter consists of (M-1)/2 H-bridges in which each bridge's dc voltage is supported by its own dc capacitor. The new inverter can: (1) generate almost sinusoidal waveform voltage while only switching one time per fundamental cycle; (2) dispense with multi-pulse inverters' transformers used in conventional utility interfaces and static var compensators; (3) enables direct parallel or series transformer-less connection to medium- and high-voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi-pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features, feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical, simulated, and experimental results demonstrated the superiority of the new inverters.

  16. Azobenzene-functionalized cascade molecules

    DEFF Research Database (Denmark)

    Archut, A.; Vogtle, F.; De Cola, L.;

    1998-01-01

    Cascade molecules bearing up to 32 azobenzene groups in the periphery have been prepared from poly(propylene imine) dendrimers and N-hydroxysuccinimide esters. The dendritic azobenzene species show similar isomerization properties as the corresponding azobenzene monomers. The all-E azobenzene...

  17. Cascaded Bragg scattering in fiber optics.

    Science.gov (United States)

    Xu, Y Q; Erkintalo, M; Genty, G; Murdoch, S G

    2013-01-15

    We report on a theoretical and experimental study of cascaded Bragg scattering in fiber optics. We show that the usual energy-momentum conservation of Bragg scattering can be considerably relaxed via cascade-induced phase-matching. Experimentally we demonstrate frequency translation over six- and 11-fold cascades, in excellent agreement with derived phase-matching conditions.

  18. Probing Intergalactic Magnetic Fields with Simulations of Electromagnetic Cascades

    CERN Document Server

    Batista, Rafael Alves; Sigl, Guenter; Vachaspati, Tanmay

    2016-01-01

    We determine the effect of intergalactic magnetic fields on the distribution of high energy gamma rays by performing three-dimensional Monte Carlo simulations of the development of gamma-ray-induced electromagnetic cascades in the magnetized intergalactic medium. We employ the so-called 'Large Sphere Observer' method to efficiently simulate blazar gamma ray halos. We study magnetic fields with a Batchelor spectrum and with maximal left- and right-handed helicities. We also consider the case of sources whose jets are tilted with respect to the line of sight. We verify the formation of extended gamma ray halos around the source direction, and observe spiral-like patterns if the magnetic field is helical. We apply the $Q$-statistics to the simulated halos to extract their spiral nature and also propose an alternative method, the $S$-statistics. Both methods provide a quantative way to infer the helicity of the intervening magnetic fields from the morphology of individual blazar halos for magnetic field strengths...

  19. Measurement of the nuclear electromagnetic cascade development in glass at energies above 200 GeV

    Science.gov (United States)

    Gillespie, C. R.; Huggett, R. W.; Humphreys, D. R.; Jones, W. V.; Levit, L. B.

    1971-01-01

    The longitudinal development of nuclear-electromagnetic cascades with energies greater than 200 GeV was measured in a low-Z (glass) absorber. This was done in the course of operating an ionization spectrometer at mountain altitude in an experiment to study the properties of gamma rays emitted from individual interactions at energies around 10,000 GeV. The ionization produced by a cascade is sampled by 20 sheets of plastic scintillator spaced uniformly in depth every 2.2 radiation lengths. Adjacent pairs of scintillators are viewed by photomultipliers which measure the mean ionization produced by an individual cascade in 10 layers each 1.1 interaction length (4.4 radiation lengths) thick. The longitudinal development of the cascades was measured for about 250 cascades having energies ranging from 200 GeV to 2500 GeV. The observations are compared with the predictions of calculations made for this specific spectrometer using a three-dimensional Monte Carlo model of the nuclear-electromagnetic cascade.

  20. Gamma watermarking

    Science.gov (United States)

    Ishikawa, Muriel Y.; Wood, Lowell L.; Lougheed, Ronald W.; Moody, Kenton J.; Wang, Tzu-Fang

    2004-05-25

    A covert, gamma-ray "signature" is used as a "watermark" for property identification. This new watermarking technology is based on a unique steganographic or "hidden writing" digital signature, implemented in tiny quantities of gamma-ray-emitting radioisotopic material combinations, generally covertly emplaced on or within an object. This digital signature may be readily recovered at distant future times, by placing a sensitive, high energy-resolution gamma-ray detecting instrument reasonably precisely over the location of the watermark, which location may be known only to the object's owner; however, the signature is concealed from all ordinary detection means because its exceedingly low level of activity is obscured by the natural radiation background (including the gamma radiation naturally emanating from the object itself, from cosmic radiation and material surroundings, from human bodies, etc.). The "watermark" is used in object-tagging for establishing object identity, history or ownership. It thus may serve as an aid to law enforcement officials in identifying stolen property and prosecuting theft thereof. Highly effective, potentially very low cost identification-on demand of items of most all types is thus made possible.

  1. Gamma watermarking

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, Muriel Y.; Wood, Lowell L.; Lougheed, Ronald W.; Moody, Kenton J.; Wang, Tzu-Fang

    2004-05-25

    A covert, gamma-ray "signature" is used as a "watermark" for property identification. This new watermarking technology is based on a unique steganographic or "hidden writing" digital signature, implemented in tiny quantities of gamma-ray-emitting radioisotopic material combinations, generally covertly emplaced on or within an object. This digital signature may be readily recovered at distant future times, by placing a sensitive, high energy-resolution gamma-ray detecting instrument reasonably precisely over the location of the watermark, which location may be known only to the object's owner; however, the signature is concealed from all ordinary detection means because its exceedingly low level of activity is obscured by the natural radiation background (including the gamma radiation naturally emanating from the object itself, from cosmic radiation and material surroundings, from human bodies, etc.). The "watermark" is used in object-tagging for establishing object identity, history or ownership. It thus may serve as an aid to law enforcement officials in identifying stolen property and prosecuting theft thereof. Highly effective, potentially very low cost identification-on demand of items of most all types is thus made possible.

  2. Gamma camera

    International Nuclear Information System (INIS)

    The design of a collimation system for a gamma camera for use in nuclear medicine is described. When used with a 2-dimensional position sensitive radiation detector, the novel system can produce superior images than conventional cameras. The optimal thickness and positions of the collimators are derived mathematically. (U.K.)

  3. Cascade Chaotic System With Applications.

    Science.gov (United States)

    Zhou, Yicong; Hua, Zhongyun; Pun, Chi-Man; Chen, C L Philip

    2015-09-01

    Chaotic maps are widely used in different applications. Motivated by the cascade structure in electronic circuits, this paper introduces a general chaotic framework called the cascade chaotic system (CCS). Using two 1-D chaotic maps as seed maps, CCS is able to generate a huge number of new chaotic maps. Examples and evaluations show the CCS's robustness. Compared with corresponding seed maps, newly generated chaotic maps are more unpredictable and have better chaotic performance, more parameters, and complex chaotic properties. To investigate applications of CCS, we introduce a pseudo-random number generator (PRNG) and a data encryption system using a chaotic map generated by CCS. Simulation and analysis demonstrate that the proposed PRNG has high quality of randomness and that the data encryption system is able to protect different types of data with a high-security level.

  4. Bankruptcy cascades in interbank markets.

    Directory of Open Access Journals (Sweden)

    Gabriele Tedeschi

    Full Text Available We study a credit network and, in particular, an interbank system with an agent-based model. To understand the relationship between business cycles and cascades of bankruptcies, we model a three-sector economy with goods, credit and interbank market. In the interbank market, the participating banks share the risk of bad debits, which may potentially spread a bank's liquidity problems through the network of banks. Our agent-based model sheds light on the correlation between bankruptcy cascades and the endogenous economic cycle of booms and recessions. It also demonstrates the serious trade-off between, on the one hand, reducing risks of individual banks by sharing them and, on the other hand, creating systemic risks through credit-related interlinkages of banks. As a result of our study, the dynamics underlying the meltdown of financial markets in 2008 becomes much better understandable.

  5. Bankruptcy Cascades in Interbank Markets

    Science.gov (United States)

    Tedeschi, Gabriele; Mazloumian, Amin; Gallegati, Mauro; Helbing, Dirk

    2012-01-01

    We study a credit network and, in particular, an interbank system with an agent-based model. To understand the relationship between business cycles and cascades of bankruptcies, we model a three-sector economy with goods, credit and interbank market. In the interbank market, the participating banks share the risk of bad debits, which may potentially spread a bank’s liquidity problems through the network of banks. Our agent-based model sheds light on the correlation between bankruptcy cascades and the endogenous economic cycle of booms and recessions. It also demonstrates the serious trade-off between, on the one hand, reducing risks of individual banks by sharing them and, on the other hand, creating systemic risks through credit-related interlinkages of banks. As a result of our study, the dynamics underlying the meltdown of financial markets in 2008 becomes much better understandable. PMID:23300760

  6. Optimally Training a Cascade Classifier

    CERN Document Server

    Shen, Chunhua; Hengel, Anton van den

    2010-01-01

    Cascade classifiers are widely used in real-time object detection. Different from conventional classifiers that are designed for a low overall classification error rate, a classifier in each node of the cascade is required to achieve an extremely high detection rate and moderate false positive rate. Although there are a few reported methods addressing this requirement in the context of object detection, there is no a principled feature selection method that explicitly takes into account this asymmetric node learning objective. We provide such an algorithm here. We show a special case of the biased minimax probability machine has the same formulation as the linear asymmetric classifier (LAC) of \\cite{wu2005linear}. We then design a new boosting algorithm that directly optimizes the cost function of LAC. The resulting totally-corrective boosting algorithm is implemented by the column generation technique in convex optimization. Experimental results on object detection verify the effectiveness of the proposed bo...

  7. Thermal cascaded lattice Boltzmann method

    CERN Document Server

    Fei, Linlin

    2016-01-01

    In this paper, a thermal cascaded lattice Boltzmann method (TCLBM) is developed in combination with the double-distribution-function (DDF) approach. A density distribution function relaxed by the cascaded scheme is employed to solve the flow field, and a total energy distribution function relaxed by the BGK scheme is used to solve temperature field, where two distribution functions are coupled naturally. The forcing terms are incorporated by means of central moments, which is consistent with the previous force scheme [Premnath \\emph{et al.}, Phys. Rev. E \\textbf{80}, 036702 (2009)] but the derivation is more intelligible and the evolution process is simpler. In the method, the viscous heat dissipation and compression work are taken into account, the Prandtl number and specific-heat ratio are adjustable, the external force is considered directly without the Boussinesq assumption, and the low-Mach number compressible flows can also be simulated. The forcing scheme is tested by simulating a steady Taylor-Green f...

  8. Constraints on the VHE Emissivity of the Universe from the Diffuse GeV Gamma-Ray Background

    OpenAIRE

    Coppi, P. S.; Aharonian, F. A.

    1996-01-01

    VHE (Very High Energy, E>100 GeV) radiation emitted at cosmological distances will pair produce on low-energy diffuse extragalactic background radiation before ever reaching us. This prevents us from directly seeing most of the VHE emission in the Universe. However, a VHE gamma-ray that pair produces initiates an electromagnetic pair cascade. At low energies, this secondary cascade radiation has a spectrum insensitive to the spectrum of the primary gamma-radiation and, unlike the original VHE...

  9. Lens Coupled Quantum Cascade Laser

    Science.gov (United States)

    Hu, Qing (Inventor); Lee, Alan Wei Min (Inventor)

    2013-01-01

    Terahertz quantum cascade (QC) devices are disclosed that can operate, e.g., in a range of about 1 THz to about 10 THz. In some embodiments, QC lasers are disclosed in which an optical element (e.g., a lens) is coupled to an output facet of the laser's active region to enhance coupling of the lasing radiation from the active region to an external environment. In other embodiments, terahertz amplifier and tunable terahertz QC lasers are disclosed.

  10. Turbulence: does energy cascade exist?

    CERN Document Server

    Josserand, Christophe; Lehner, Thierry; Pomeau, Yves

    2016-01-01

    To answer the question whether a cascade of energy exists or not in turbulence, we propose a set of correlation functions able to test if there is an irreversible transfert of energy, step by step, from large to small structures. These tests are applied to real Eulerian data of a turbulent velocity flow, taken in the wind grid tunnel of Modane, and also to a prototype model equation for wave turbulence. First we demonstrate the irreversible character of the flow by using multi-time correlation function at a given point of space. Moreover the unexpected behavior of the test function leads us to connect irreversibility and finite time singularities (intermittency). Secondly we show that turbulent cascade exists, and is a dynamical process, by using a test function depending on time and frequency. The cascade shows up only in the inertial domain where the kinetic energy is transferred more rapidly (on average) from the wavenumber $k_{1}$ to $k_{2}$ than from $k_{1}$ to $k'_{2}$ larger than $k_{2}$.

  11. Gamma-ray methods

    International Nuclear Information System (INIS)

    Bulk analysis techniques using gamma radiation are described. The methods include gamma-ray induced reactions, selective gamma-ray scattering and methods which rely on natural radioactivity. The gamma-ray resonance scattering technique can be used for the determination of copper and nickel in bulk samples and drill cores. The application of gamma-gamma methods to iron ore analysis is outlined

  12. Energy cascades in the upper ocean

    Institute of Scientific and Technical Information of China (English)

    Ray Q.Lin; Scott Chubb

    2006-01-01

    Wave-wave interactions cause energy cascades. These are the most important processes in the upper ocean because they govern wave-growth and dissipation. Through indirect cascades, wave energy is transferred from higher frequencies to lower frequencies, leading to wave growth. In direct cascades, energy is transferred from lower frequencies to the higher frequencies, which causes waves to break, and dissipation of wave energy. However, the evolution and origin of energy cascade processes are still not fully understood. In particular, for example, results from a recent theory (Kalmykov, 1998) suggest that the class I wave-wave interactions (defined by situations involving 4-, 6-, 8-, etc, even numbers of resonantly interacting waves) cause indirect cascades, and Class II wave-wave interactions (involving, 5-, 7-, 9-, etc, .., odd numbers of waves) cause direct cascades. In contrast to this theory, our model results indicate the 4-wave interactions can cause significant transfer of wave energy through both direct and indirect cascades. In most situations, 4-wave interactions provide the major source of energy transfer for both direct cascades and indirect cascades, except when the wave steepness is larger than 0.28. Our model results agree well with wave measurements, obtained using field buoy data (for example, Lin and Lin, 2002). In particular, in these observations, asymmetrical wave-wave interactions were studied. They found that direct and indirect cascades both are mainly due to the 4-wave interactions when wave steepness is less than 0.3.

  13. GARCH Gamma

    OpenAIRE

    Robert F. Engle; Joshua V. Rosenberg

    1995-01-01

    This paper addresses the issue of hedging option positions when the underlying asset exhibits stochastic volatility. By parameterizing the volatility process as GARCH, and utilizing risk- neutral valuation, we estimate hedging parameters (delta and gamma) using Monte-Carlo simulation. We estimate hedging parameters for options on the Standard and Poor's 500 index, a bond futures index, a weighted foreign exchange rate index, and an oil futures index. We find that Black-Scholes and GARCH delta...

  14. Gamma teletopography

    International Nuclear Information System (INIS)

    The mapping of gamma sources radiation emission in a nuclear plant is an important safety point. A remote gamma ray mapping process was developed in SPS/CEA/SACLAY. It uses the ''pinhole camera'' principle, precursor of photography. It mainly consists of a radiation proof box, with a small orifice, containing sensitive emulsions at the opposite. A first conventional photographic type emulsion photographs the area. A second photographic emulsion shows up the gamma radiations. The superim position of the two shots gives immediate informations of the precise location of each source of radiation in the observed area. To make easier the presentation and to improve the accuracy of the results for radiation levels mapping, the obtained films are digitally processed. The processing assigns a colours scale to the various levels of observed radiations. Taking account physical data and standard parameters, it gets possible to estimate the dose rate. The device is portable. Its compactness and fully independent nature make it suitable for use anywhere. It can be adapted to a remote automatic handling system, robot... so as to avoid all operator exposure when the local dose rate is too high

  15. A Comparison of Methods for Cascade Prediction

    CERN Document Server

    Guo, Ruocheng

    2016-01-01

    Information cascades exist in a wide variety of platforms on Internet. A very important real-world problem is to identify which information cascades can go viral. A system addressing this problem can be used in a variety of applications including public health, marketing and counter-terrorism. As a cascade can be considered as compound of the social network and the time series. However, in related literature where methods for solving the cascade prediction problem were proposed, the experimental settings were often limited to only a single metric for a specific problem formulation. Moreover, little attention was paid to the run time of those methods. In this paper, we first formulate the cascade prediction problem as both classification and regression. Then we compare three categories of cascade prediction methods: centrality based, feature based and point process based. We carry out the comparison through evaluation of the methods by both accuracy metrics and run time. The results show that feature based met...

  16. Cascade photons as test of protons in UHECR

    CERN Document Server

    Berezinsky, V; Kalashev, O

    2016-01-01

    An isotropic component of high energy $\\gamma$-ray spectrum measured by Fermi LAT constrains the proton component of UHECR. The strongest restriction comes from the highest, $(580-820)$ GeV, energy bin. One more constraint on the proton component is provided by the IceCube upper bound on ultrahigh energy cosmogenic neutrino flux. We study the influence of these restrictions on the source properties, such as evolution and distribution of sources, their energy spectrum and admixture of nuclei. We also study the sensitivity of restrictions to various Fermi LAT galactic foreground models (model B being less restrictive), to the choice of extragalactic background light model and to overall normalization of the energy spectrum. We claim that the $\\gamma$-ray-cascade constraints are stronger than the neutrino ones, and that however many proton models are viable. The basic parameters of such models are relatively large $\\gamma_g$ and not very large $z_{\\max}$. The allowance for H$e^4$ admixture also relaxes the restr...

  17. Lateral Modes in Quantum Cascade Lasers

    Directory of Open Access Journals (Sweden)

    Gregory C. Dente

    2016-03-01

    Full Text Available We will examine the waveguide mode losses in ridge-guided quantum cascade lasers. Our analysis illustrates how the low-loss mode for broad-ridge quantum cascade lasers (QCLs can be a higher-order lateral waveguide mode that maximizes the feedback from the sloped ridge-wall regions. The results are in excellent agreement with the near- and far-field data taken on broad-ridge-guided quantum cascade lasers processed with sloped ridge walls.

  18. Disaster Mythology and Availability Cascades

    Directory of Open Access Journals (Sweden)

    Lisa Grow Sun

    2013-04-01

    Full Text Available Sociological research conducted in the aftermath of natural disasters has uncovered a number of “disaster myths” – widely shared misconceptions about typical post-disaster human behavior. This paper discusses the possibility that perpetuation of disaster mythology reflects an “availability cascade,” defined in prior scholarship as a “self-reinforcing process of collective belief formation by which an expressed perception triggers a chain reaction that gives the perception increasing plausibility through its rising availability in public discourse.” (Kuran and Sunstein 1999. Framing the spread of disaster mythology as an availability cascade suggests that certain tools may be useful in halting the myths’ continued perpetuation. These tools include changing the legal and social incentives of so-called “availability entrepreneurs” – those principally responsible for beginning and perpetuating the cascade, as well as insulating decision-makers from political pressures generated by the availability cascade. This paper evaluates the potential effectiveness of these and other solutions for countering disaster mythology. Las investigaciones sociológicas realizadas tras los desastres naturales han hecho evidentes una serie de “mitos del desastre”, conceptos erróneos ampliamente compartidos sobre el comportamiento humano típico tras un desastre. Este artículo analiza la posibilidad de que la perpetuación de los mitos del desastre refleje una “cascada de disponibilidad”, definida en estudios anteriores como un “proceso de auto-refuerzo de la formación de una creencia colectiva, a través del que una percepción expresada produce una reacción en cadena que hace que la percepción sea cada vez más verosímil, a través de una mayor presencia en el discurso público” (Kuran y Sunstein 1999. Enmarcar la propagación de los mitos del desastre como una cascada de disponibilidad sugiere que ciertas herramientas pueden ser

  19. Spray formation: an inverse cascade

    CERN Document Server

    Ling, Yue; Tryggvason, Gretar; zaleski, Stephane

    2015-01-01

    We present a study of droplet formation in a gas-liquid mixing layer using direct numerical simulation. It is seen that two mechanisms compete to generate the droplets: fingering at the tip of the waves and hole formation in the thin liquid sheet. The three dimensional liquid structures are much shorter than the longitudinal wavelength of the instability at the first instant of their formation. As time evolves, the structures evolves to larger and larger scales, in a way similar to the inverse cascade of length scales in droplet impact and impact crown formation.

  20. WHISTLER TURBULENCE FORWARD CASCADE VERSUS INVERSE CASCADE: THREE-DIMENSIONAL PARTICLE-IN-CELL SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Ouliang [Oracle Corporation, Redwood Shores, CA (United States); Gary, S. Peter [Space Science Institute, Boulder, CO (United States); Wang, Joseph, E-mail: ouliang@usc.edu, E-mail: pgary@lanl.gov, E-mail: josephjw@usc.edu [University of Southern California, Los Angeles, CA (United States)

    2015-02-20

    We present the results of the first fully three-dimensional particle-in-cell simulations of decaying whistler turbulence in a magnetized, homogeneous, collisionless plasma in which both forward cascades to shorter wavelengths, and inverse cascades to longer wavelengths are allowed to proceed. For the electron beta β {sub e} = 0.10 initial value considered here, the early-time rate of inverse cascade is very much smaller than the rate of forward cascade, so that at late times the fluctuation energy in the regime of the inverse cascade is much weaker than that in the forward cascade regime. Similarly, the wavevector anisotropy in the inverse cascade regime is much weaker than that in the forward cascade regime.

  1. Single-Seed Cascades on Clustered Networks

    CERN Document Server

    McSweeney, John K

    2015-01-01

    We consider a dynamic network cascade process developed by Watts applied to a random networks with a specified amount of clustering, belonging to a class of random networks developed by Newman. We adapt existing tree-based methods to formulate an appropriate two-type branching process to describe the spread of a cascade started with a single active node, and obtain a fixed-point equation to implicitly express the extinction probability of such a cascade. In so doing, we also recover a special case of a formula of Hackett et al. giving conditions for certain extinction of the cascade.

  2. Unsteady transonic flow over cascade blades

    Science.gov (United States)

    Surampudi, S. P.; Adamczyk, J. J.

    1986-01-01

    An attempt is made to develop an efficient staggered cascade blade unsteady aerodynamics model for the neighborhood of March 1, representing the blade row by a rectilinear two-dimensional cascade of thin, flat plate airfoils. The equations of motion are derived on the basis of linearized transonic small perturbation theory, and an analytical solution is obtained by means of the Wiener-Hopf procedure. Making use of the transonic similarity law, the results obtained are compared with those of other linearized cascade analyses. A parametric study is conducted to find the effects of reduced frequency, stagger angle, solidity, and the location of the pitching axis on cascade stability.

  3. Contingency Analysis of Cascading Line Outage Events

    Energy Technology Data Exchange (ETDEWEB)

    Thomas L Baldwin; Magdy S Tawfik; Miles McQueen

    2011-03-01

    As the US power systems continue to increase in size and complexity, including the growth of smart grids, larger blackouts due to cascading outages become more likely. Grid congestion is often associated with a cascading collapse leading to a major blackout. Such a collapse is characterized by a self-sustaining sequence of line outages followed by a topology breakup of the network. This paper addresses the implementation and testing of a process for N-k contingency analysis and sequential cascading outage simulation in order to identify potential cascading modes. A modeling approach described in this paper offers a unique capability to identify initiating events that may lead to cascading outages. It predicts the development of cascading events by identifying and visualizing potential cascading tiers. The proposed approach was implemented using a 328-bus simplified SERC power system network. The results of the study indicate that initiating events and possible cascading chains may be identified, ranked and visualized. This approach may be used to improve the reliability of a transmission grid and reduce its vulnerability to cascading outages.

  4. Cascade decays of hollow ions

    International Nuclear Information System (INIS)

    A multiple-electron-emission process for atoms with one or more inner-shell vacancies is treated using the radiative- and Auger-electron-emission cascade model, in which inner-shell holes are assumed to decay by sequentially emitting radiations and/or Auger electrons. Such hollow ions are produced by synchrotron irradiation of atomic targets and in ion-surface interactions with multiple-electron transfers. The final charge-state distribution is determined by the Auger and radiative branching ratios at each stage of the decay sequence. At intermediate stages of cascade, hollow ions with more than one hole in different ionization stages are created. The Ne, Mg, and Fe14+ ions with the initial 1s, 2s, and 2p vacancies are considered in detail, and the core charge dependence of the maximum charge state is studied. The hollow Mg ion with double initial 1s holes is analyzed, and the result compared with that for the case of one 1s hole. The peak is shifted more than two units to a higher degree of ionization. The correlated shake-off and shake-up multiple-electron processes are not considered, but they are expected to cause further shifts

  5. Multifunctional Cascaded Metamaterials: Integrated Transmitarrays

    Science.gov (United States)

    Elsakka, Amr A.; Asadchy, Viktar S.; Faniayeu, Ihar A.; Tcvetkova, Svetlana N.; Tretyakov, Sergei A.

    2016-10-01

    Control of electromagnetic waves using engineered materials is very important in a wide range of applications, therefore there is always a continuous need for new and more efficient solutions. Known natural and artificial materials and surfaces provide a particular functionality in the frequency range they operate but cast a "shadow" and produce reflections at other frequencies. Here, we introduce a concept of multifunctional engineered materials that possess different predetermined functionalities at different frequencies. Such response can be accomplished by cascading metasurfaces (thin composite layers) that are designed to perform a single operation at the desired frequency and are transparent elsewhere. Previously, out-of-band transparent metasurfaces for control over reflection and absorption were proposed. In this paper, to complete the full set of functionalities for wave control, we synthesize transmitarrays that tailor transmission in a desired way, being "invisible" beyond the operational band. The designed transmitarrays for wavefront shaping and anomalous refraction are tested numerically and experimentally. To demonstrate our concept of multifunctional engineered materials, we have designed a cascade of three metasurfaces that performs three different functions for waves at different frequencies. Remarkably, applied to volumetric metamaterials, our concept can enable a single composite possessing desired multifunctional response.

  6. Physics of interband cascade lasers

    Science.gov (United States)

    Vurgaftman, I.; Bewley, W. W.; Merritt, C. D.; Canedy, C. L.; Kim, C. S.; Abell, J.; Meyer, J. R.; Kim, M.

    2012-01-01

    The interband cascade laser (ICL) is a unique device concept that combines the effective parallel connection of its multiple-quantum-well active regions, interband active transitions, and internal generation of electrons and holes at a semimetallic interface within each stage of the device. The internal generation of carriers becomes effective under bias, and the role of electrical injection is to replenish the carriers consumed by recombination processes. Major strides have been made toward fundamentally understanding the rich and intricate ICL physics, which has in turn led to dramatic improvements in the device performance. In this article, we review the physical principles of the ICL operation and designs of the active region, electron and hole injectors, and optical waveguide. The results for state-of- the-art ICLs spanning the 3-6 μm wavelength range are also briefly reviewed. The cw threshold input powers at room temperature are more than an order of magnitude lower than those for quantum cascade lasers throughout the mid-IR spectral range. This will lengthen battery lifetimes and greatly relax packaging and size/weight requirements for fielded sensing systems.

  7. Gamma-ray astronomy: From Fermi up to the HAWC high-energy {gamma}-ray observatory in Sierra Negra

    Energy Technology Data Exchange (ETDEWEB)

    Carraminana, Alberto [Instituto Nacional de Astrofisica, Optica y Electronica Luis Enrique Erro 1, Tonantzintla, Puebla 72840 (Mexico); Collaboration: HAWC Collaboration

    2013-06-12

    Gamma-rays represent the most energetic electromagnetic window for the study of the Universe. They are studied both from space at MeV and GeV energies, with instruments like the Fermi{gamma}-ray Space Telescope, and at TeV energies with ground based instruments profiting of particle cascades in the atmosphere and of the Cerenkov radiation of charged particles in the air or in water. The Milagro gamma-ray observatory represented the first instrument to successfully implement the water Cerenkov technique for {gamma}-ray astronomy, opening the ground for the more sensitive HAWC {gamma}-ray observatory, currently under development in the Sierra Negra site and already providing early science results.

  8. Nonlinearly Driven Second Harmonics of Alfven Cascades

    International Nuclear Information System (INIS)

    In recent experiments on Alcator C-Mod, measurements of density fluctuations with Phase Contrast Imaging through the plasma core show a second harmonic of the basic Alfven Cascade (AC) signal. The present work describes the perturbation at the second harmonic as a nonlinear sideband produced by the Alfven Cascade eigenmode via quadratic terms in the MHD equations. (author)

  9. Design concept of Hydro cascade control system

    International Nuclear Information System (INIS)

    In this paper a design concept of the comple hydro cascade scheme is presented with the design parameters of the main technical features. The cascade control system architecture is designed considering up-to-date communication and information technology. The control algorithm is based on Pond Level Control and Economic Load Allocation concepts.

  10. Cascading costs: An economic nitrogen cycle

    Institute of Scientific and Technical Information of China (English)

    William; R.; Moomaw; Melissa; B.; L.; Birch

    2005-01-01

    The chemical nitrogen cycle is becoming better characterized in terms of fluxes and reservoirs on a variety of scales. Galloway has demonstrated that reactive nitrogen can cascade through multiple ecosystems causing environmental damage at each stage before being denitrifled to N2. We propose to construct a parallel economic nitrogen cascade (ENC) in which economic impacts of nitrogen fluxes can be estimated by the costs associated with each stage of the chemical cascade. Using economic data for the benefits of damage avoided and costs of mitigation in the Chesapeake Bay basin, we have constructed an economic nitrogen cascade for the region. Since a single tonne of nitrogen can cascade through the system, the costs also cascade.Therefore evaluating the benefits of mitigating a tonne of reactive nitrogen released needs to consider the damage avoided in all of the ecosystems through which that tonne would cascade.The analysis reveals that it is most cost effective to remove a tonne of nitrogen coming from combustion since it has the greatest impact on human health and creates cascading damage through the atmospheric, terrestrial, aquatic and coastal ecosystems. We will discuss the implications of this analysis for determining the most cost effective policy option for achieving environmental quality goals.

  11. Fractal dimensionality of cascades of atomic displacements

    International Nuclear Information System (INIS)

    The cascades of opening displacements, formed during irradiation of solids are the most typical process of dissipation of the energy of incident particles and the generation of radiation defects. The aim of the present work is the examination of the energy dependence of the fractal dimensionality of the cascades of atomic displacements in the solid

  12. A NOTE ON VECTOR CASCADE ALGORITHM

    Institute of Scientific and Technical Information of China (English)

    Qiu-hui Chen; Jin-zhao Liu; Wen-sheng Zhang

    2002-01-01

    The focus of this paper is on the relationship between accuracy of multivariate refinable vector and vector cascade algorithm. We show that, if the vector cascade algorithm (1.5) with isotropic dilation converges to a vector-valued function with regularity, then the initial function must satisfy the Strang-Fix conditions.

  13. Cascade Harvest’ red raspberry

    Science.gov (United States)

    Cascade Harvest’ is a new floricane fruiting raspberry cultivar (Rubus idaeus L.) jointly released by Washington State University (WSU), Oregon State University (OSU) and the U.S. Department of Agriculture (USDA). ‘Cascade Harvest’ produces a high yield of large, firm fruit suited to machine harves...

  14. Fuzzy Gamma-hypersemigroups

    OpenAIRE

    R. Ameri; Sadeghi, R.

    2013-01-01

    We introduced and study fuzzy gamma-hypersemigroups, according to fuzzy semihyper- groups as previously defined [33] and prove that results in this respect. In this regard first we introduce fuzzy hyperoperation and then study fuzzy gamma-hypersemigroup. We will proceed by study fuzzy gamma-hyperideals and fuzzy gamma-bihyperideals. Also we study the relation between the classes of fuzzy gamma-hypersemigroups and semigroups. Precisely, we associate a gamma-hypersemigroup to every fuzzy hypers...

  15. Cascade Error Projection: An Efficient Hardware Learning Algorithm

    Science.gov (United States)

    Duong, T. A.

    1995-01-01

    A new learning algorithm termed cascade error projection (CEP) is presented. CEP is an adaption of a constructive architecture from cascade correlation and the dynamical stepsize of A/D conversion from the cascade back propagation algorithm.

  16. MAPK Cascades in Guard Cell Signal Transduction

    Science.gov (United States)

    Lee, Yuree; Kim, Yun Ju; Kim, Myung-Hee; Kwak, June M.

    2016-01-01

    Guard cells form stomata on the epidermis and continuously respond to endogenous and environmental stimuli to fine-tune the gas exchange and transpirational water loss, processes which involve mitogen-activated protein kinase (MAPK) cascades. MAPKs form three-tiered kinase cascades with MAPK kinases and MAPK kinase kinases, by which signals are transduced to the target proteins. MAPK cascade genes are highly conserved in all eukaryotes, and they play crucial roles in myriad developmental and physiological processes. MAPK cascades function during biotic and abiotic stress responses by linking extracellular signals received by receptors to cytosolic events and gene expression. In this review, we highlight recent findings and insights into MAPK-mediated guard cell signaling, including the specificity of MAPK cascades and the remaining questions. PMID:26904052

  17. MAPK cascades in guard cell signal transduction

    Directory of Open Access Journals (Sweden)

    Yuree eLee

    2016-02-01

    Full Text Available Guard cells form stomata on the epidermis and continuously respond to endogenous and environmental stimuli to fine-tune the gas exchange and transpirational water loss, processes which involve mitogen-activated protein kinase (MAPK cascades. MAPKs form three-tiered kinase cascades with MAPK kinases and MAPK kinase kinases, by which signals are transduced to the target proteins. MAPK cascade genes are highly conserved in all eukaryotes, and they play crucial roles in myriad developmental and physiological processes. MAPK cascades function during biotic and abiotic stress responses by linking extracellular signals received by receptors to cytosolic events and gene expression. In this review, we highlight recent findings and insights into MAPK-mediated guard cell signaling, including the specificity of MAPK cascades and the remaining questions.

  18. Stochastic annealing simulation of cascades in metals

    Energy Technology Data Exchange (ETDEWEB)

    Heinisch, H.L.

    1996-04-01

    The stochastic annealing simulation code ALSOME is used to investigate quantitatively the differential production of mobile vacancy and SIA defects as a function of temperature for isolated 25 KeV cascades in copper generated by MD simulations. The ALSOME code and cascade annealing simulations are described. The annealing simulations indicate that the above Stage V, where the cascade vacancy clusters are unstable,m nearly 80% of the post-quench vacancies escape the cascade volume, while about half of the post-quench SIAs remain in clusters. The results are sensitive to the relative fractions of SIAs that occur in small, highly mobile clusters and large stable clusters, respectively, which may be dependent on the cascade energy.

  19. Multiscales and cascade in isotropic turbulence

    CERN Document Server

    Ran, Zheng

    2010-01-01

    The central problem of fully developed turbulence is the energy cascading process. It has revisited all attempts at a full physical understanding or mathematical formulation. The main reason for this failure are related to the large hierarchy of scales involved, the highly nonlinear character inherent in the Navier-Stokes equations, and the spatial intermittency of the dynamically active regions. Richardson has described the interplay between large and small scales and the phenomena so described are known as the Richardson cascade. This local interplay also forms the basis of a theory by Kolmogorov. In this letter, we use the explicit map method to analyze the nonlinear dynamical behavior for cascade in isotropic turbulence. This deductive scale analysis is shown to provide the first visual evidence of the celebrated Richardson cascade, and reveals in particular its multiscale character. The results also indicate that the energy cascading process has remarkable similarities with the deterministic construction...

  20. Network reconstruction from infection cascades

    CERN Document Server

    Braunstein, Alfredo

    2016-01-01

    Reconstructing propagation networks from observations is a fundamental inverse problem, and it's crucial to understand and control dynamics in complex systems. Here we show that it is possible to reconstruct the whole structure of an interaction network and to simultaneously infer the complete time course of activation spreading, relying just on single snapshots of a small number of activity cascades. The method, that we called Inverse Dynamics Network Reconstruction (IDNR), is shown to work successfully on several synthetic and real networks, inferring the networks and the sources of infection based on sparse observations, including single snapshots. IDNR is built on a Belief Propagation approximation, that has an impressive performance in a wide variety of topological structures. The method can be applied in absence of complete time-series data by providing a detailed modeling of the posterior distribution of trajectories conditioned to the observations. Furthermore, we show by experiments that the informat...

  1. Availability Cascades & the Sharing Economy

    DEFF Research Database (Denmark)

    Netter, Sarah

    2014-01-01

    In search of a new concept that will provide answers to as to how modern societies should not only make sense but also resolve the social and environmental problems linked with our modes of production and consumption, collaborative consumption and the sharing economy are increasingly attracting...... attention. This conceptual paper attempts to explain the emergent focus on the sharing economy and associated business and consumption models by applying cascade theory. Risks associated with this behavior will be especially examined with regard to the sustainability claim of collaborative consumption....... With academics, practitioners, and civil society alike having a shared history in being rather fast in accepting new concepts that will not only provide business opportunities but also a good conscience, this study proposes a critical study of the implications of collaborative consumption, before engaging...

  2. Cascades in interdependent flow networks

    Science.gov (United States)

    Scala, Antonio; De Sanctis Lucentini, Pier Giorgio; Caldarelli, Guido; D'Agostino, Gregorio

    2016-06-01

    In this manuscript, we investigate the abrupt breakdown behavior of coupled distribution grids under load growth. This scenario mimics the ever-increasing customer demand and the foreseen introduction of energy hubs interconnecting the different energy vectors. We extend an analytical model of cascading behavior due to line overloads to the case of interdependent networks and find evidence of first order transitions due to the long-range nature of the flows. Our results indicate that the foreseen increase in the couplings between the grids has two competing effects: on the one hand, it increases the safety region where grids can operate without withstanding systemic failures; on the other hand, it increases the possibility of a joint systems' failure.

  3. Cascades in interdependent flow networks

    CERN Document Server

    Scala, Antonio; Caldarelli, Guido; D'Agostino, Gregorio

    2015-01-01

    We investigate the abrupt breakdown behavior of coupled distribution grids under load growth. This scenario mimics the ever-increasing customer demand and the foreseen introduction of energy hubs interconnecting the different energy vectors. We extend an analytical model of cascading behavior due to line overloads to the case of interdependent networks and find evidence of first order transitions due to the long-range nature of the flows. Our results indicate that the foreseen increase in the couplings between the grids has two competing effects: on the one hand, it increases the safety region where grids can operate without withstanding systemic failures; on the other hand, it increases the possibility of a joint systems' failure.

  4. Multifunctional Cascaded Metamaterials: Integrated Transmitarrays

    CERN Document Server

    Elsakka, Amr A; Faniayeu, Ihar A; Tcvetkova, Svetlana N; Tretyakov, Sergei A

    2016-01-01

    Control of electromagnetic waves using engineered materials is very important in a wide range of applications, therefore there is always a continuous need for new and more efficient solutions. Known natural and artificial materials and surfaces provide a particular functionality in the frequency range they operate but cast a "shadow" and produce reflections at other frequencies. Here, we introduce a concept of multifunctional engineered materials that possess different predetermined functionalities at different frequencies. Such response can be accomplished by cascading metasurfaces (thin composite layers) that are designed to perform a single operation at the desired frequency and are transparent elsewhere. Previously, out-of-band transparent metasurfaces for control over reflection and absorption were proposed. In this paper, to complete the full set of functionalities for wave control, we synthesize transmitarrays that tailor transmission in a desired way, being "invisible" beyond the operational band. The...

  5. On semi-exclusive measurement of $\\gamma\\gamma\\to\\gamma\\gamma$ scattering

    CERN Document Server

    Staszewski, Rafał

    2016-01-01

    The two-photon production of photon pairs, i.e. the $\\gamma\\gamma\\to\\gamma\\gamma$ process, is studied. Different production modes regarding the elastic or inelastic coupling of the intermediate-state photons to the protons are considered. The semi-exclusive measurement, where one intact proton is registered by a dedicated forward proton detector, is discussed. As an example, the signal and background simulations are performed for the $\\gamma\\gamma\\to\\gamma\\gamma$ process mediated by the hypothetical 750 GeV resonance.

  6. GAMMA-400 gamma-ray observatory

    CERN Document Server

    Topchiev, N P; Bonvicini, V; Adriani, O; Aptekar, R L; Arkhangelskaja, I V; Arkhangelskiy, A I; Bakaldin, A V; Bergstrom, L; Berti, E; Bigongiari, G; Bobkov, S G; Boezio, M; Bogomolov, E A; Bonechi, L; Bongi, M; Bottai, S; Castellini, G; Cattaneo, P W; Cumani, P; Dalkarov, O D; Dedenko, G L; De Donato, C; Dogiel, V A; Finetti, N; Gascon, D; Gorbunov, M S; Gusakov, Yu V; Hnatyk, B I; Kadilin, V V; Kaplin, V A; Kaplun, A A; Kheymits, M D; Korepanov, V E; Larsson, J; Leonov, A A; Loginov, V A; Longo, F; Maestro, P; Marrocchesi, P S; Martinez, M; Menshenin, A L; Mikhailov, V V; Mocchiutti, E; Moiseev, A A; Mori, N; Moskalenko, I V; Naumov, P Yu; Papini, P; Paredes, J M; Pearce, M; Picozza, P; Rappoldi, A; Ricciarini, S; Runtso, M F; Ryde, F; Serdin, O V; Sparvoli, R; Spillantini, P; Stozhkov, Yu I; Suchkov, S I; Taraskin, A A; Tavani, M; Tiberio, A; Tyurin, E M; Ulanov, M V; Vacchi, A; Vannuccini, E; Vasilyev, G I; Ward, J E; Yurkin, Yu T; Zampa, N; Zirakashvili, V N; Zverev, V G

    2015-01-01

    The GAMMA-400 gamma-ray telescope with excellent angular and energy resolutions is designed to search for signatures of dark matter in the fluxes of gamma-ray emission and electrons + positrons. Precision investigations of gamma-ray emission from Galactic Center, Crab, Vela, Cygnus, Geminga, and other regions will be performed, as well as diffuse gamma-ray emission, along with measurements of high-energy electron + positron and nuclei fluxes. Furthermore, it will study gamma-ray bursts and gamma-ray emission from the Sun during periods of solar activity. The energy range of GAMMA-400 is expected to be from ~20 MeV up to TeV energies for gamma rays, up to 20 TeV for electrons + positrons, and up to 10E15 eV for cosmic-ray nuclei. For high-energy gamma rays with energy from 10 to 100 GeV, the GAMMA-400 angular resolution improves from 0.1{\\deg} to ~0.01{\\deg} and energy resolution from 3% to ~1%; the proton rejection factor is ~5x10E5. GAMMA-400 will be installed onboard the Russian space observatory.

  7. Stochastic Gyroresonant Acceleration for Hard Electron Spectra of Blazars: Effect of Damping of Cascading Turbulence

    CERN Document Server

    Kakuwa, Jun

    2015-01-01

    Stochastic acceleration of nonthermal electrons is investigated in the context of hard photon spectra of blazars. It is well known that this acceleration mechanism can produce a hard electron spectrum of $m \\equiv \\partial \\ln n_{\\rm e}(\\gamma)/\\partial \\ln \\gamma = 2$ with the high-energy cutoff, called an ultrarelativistic Maxwellian-like distribution, where $n_{\\rm e}(\\gamma)$ is an electron energy spectrum. We revisit the formation of this characteristic spectrum, considering a particular situation where the electrons are accelerated through gyroresonant interaction with magnetohydrodynamic wave turbulence driven by the turbulent cascade. By solving kinetic equations of the turbulent fields, electrons, and photons emitted via the synchrotron self-Compton (SSC) process, we demonstrate that in the non-test-particle treatment, the formation of a Maxwellian-like distribution is prevented by the damping effect on the turbulent fields due to the electron acceleration, at least unless an extreme parameter value ...

  8. Genetic algorithm based separation cascade optimization

    International Nuclear Information System (INIS)

    The conventional separation cascade design procedure does not give an optimum design because of squaring-off, variation of flow rates and separation factor of the element with respect to stage location. Multi-component isotope separation further complicates the design procedure. Cascade design can be stated as a constrained multi-objective optimization. Cascade's expectation from the separating element is multi-objective i.e. overall separation factor, cut, optimum feed and separative power. Decision maker may aspire for more comprehensive multi-objective goals where optimization of cascade is coupled with the exploration of separating element optimization vector space. In real life there are many issues which make it important to understand the decision maker's perception of cost-quality-speed trade-off and consistency of preferences. Genetic algorithm (GA) is one such evolutionary technique that can be used for cascade design optimization. This paper addresses various issues involved in the GA based multi-objective optimization of the separation cascade. Reference point based optimization methodology with GA based Pareto optimality concept for separation cascade was found pragmatic and promising. This method should be explored, tested, examined and further developed for binary as well as multi-component separations. (author)

  9. Epidemic and Cascading Survivability of Complex Networks

    DEFF Research Database (Denmark)

    Manzano, Marc; Calle, Eusebi; Ripoll, Jordi;

    2014-01-01

    networks. For this reason, in this paper, we propose two measures to evaluate the vulnerability of complex networks in two different dynamic multiple failure scenarios: epidemic-like and cascading failures. Firstly, we present epidemic survivability ( ES ), a new network measure that describes...... the vulnerability of each node of a network under a specific epidemic intensity. Secondly, we propose cascading survivability ( CS ), which characterizes how potentially injurious a node is according to a cascading failure scenario. Then, we show that by using the distribution of values obtained from ES and CS...

  10. Modulation gamma resonance spectroscopy

    International Nuclear Information System (INIS)

    Possibility to control dynamic processes in a matter through gamma-resonance modulation by high-frequency external variable fields in excess of inverse lifetimes of the Moessbauer nuclei excited states, that is, within the megahertz frequency range lies in the heart of the modulation gamma-resonance spectroscopy. Through the use of the gamma-resonance process theoretical analysis methods and of the equation solution method for the density matrix with the secondary quantization of gamma-radiation field one attacks the problems dealing with the effect of both variable fields and relaxation on gamma-resonance. One has studied the gamma-radiation ultrasound modulation stages. One points out a peculiar role of the gamma-magnetic resonance effect in modulation gamma resonance spectroscopy formation. One forecasts development of the modulation gamma-resonance spectroscopy into the nonlinear gamma-resonance spectroscopy

  11. A honey bee hexamerin, HEX 70a, is likely to play an intranuclear role in developing and mature ovarioles and testioles.

    Directory of Open Access Journals (Sweden)

    Juliana R Martins

    Full Text Available Insect hexamerins have long been known as storage proteins that are massively synthesized by the larval fat body and secreted into hemolymph. Following the larval-to-pupal molt, hexamerins are sequestered by the fat body via receptor-mediated endocytosis, broken up, and used as amino acid resources for metamorphosis. In the honey bee, the transcript and protein subunit of a hexamerin, HEX 70a, were also detected in ovaries and testes. Aiming to identify the subcellular localization of HEX 70a in the female and male gonads, we used a specific antibody in whole mount preparations of ovaries and testes for analysis by confocal laser-scanning microscopy. Intranuclear HEX 70a foci were evidenced in germ and somatic cells of ovarioles and testioles of pharate-adult workers and drones, suggesting a regulatory or structural role. Following injection of the thymidine analog EdU we observed co-labeling with HEX 70a in ovariole cell nuclei, inferring possible HEX 70a involvement in cell proliferation. Further support to this hypothesis came from an injection of anti-HEX 70a into newly ecdysed queen pupae where it had a negative effect on ovariole thickening. HEX 70a foci were also detected in ovarioles of egg laying queens, particularly in the nuclei of the highly polyploid nurse cells and in proliferating follicle cells. Additional roles for this storage protein are indicated by the detection of nuclear HEX 70a foci in post-meiotic spermatids and spermatozoa. Taken together, these results imply undescribed roles for HEX 70a in the developing gonads of the honey bee and raise the possibility that other hexamerins may also have tissue specific functions.

  12. Gamma-ray strength functions in thermally excited rotating nuclei

    CERN Document Server

    Døssing, T; Maj, A; Matsuo, M; Vigezzi, E; Bracco, A; Leoni, S; Broglia, R A

    2001-01-01

    A general discussion and illustration is given of strength functions for rotational transitions in two-dimensional E(gamma_1) x E(gamma_2) spectra. Especially, a narrow component should be proportional to the compound damping width, related to the mixing of basis rotational bands into compound bands with fragmented transition strength. Three E(gamma_1) x E(gamma_2) spectra are made by setting gates on triple coincidences, selecting cascades which feed into specific low-lying bands in the nucleus 168Hf. In each of the gated spectra, we find a ridge, carrying about 100 decay paths. This ridge is ascribed to rotational transitions in the excitation energy range of 1.0 to 1.5 MeV above the yrast line. The FWHM of the ridges are around 40 keV, about a factor of two smaller than calculated on the basis of mixed cranked mean field bands.

  13. Cascading blockages in channel bundles.

    Science.gov (United States)

    Barré, C; Talbot, J

    2015-11-01

    Flow in channel networks may involve a redistribution of flux following the blockage or failure of an individual link. Here we consider a simplified model consisting of N(c) parallel channels conveying a particulate flux. Particles enter these channels according to a homogeneous Poisson process and an individual channel blocks if more than N particles are simultaneously present. The behavior of the composite system depends strongly on how the flux of entering particles is redistributed following a blockage. We consider two cases. In the first, the intensity on each open channel remains constant while in the second the total intensity is evenly redistributed over the open channels. We obtain exact results for arbitrary N(c) and N for a system of independent channels and for arbitrary N(c) and N=1 for coupled channels. For N>1 we present approximate analytical as well as numerical results. Independent channels block at a decreasing rate due to a simple combinatorial effect, while for coupled channels the interval between successive blockages remains constant for N=1 but decreases for N>1. This accelerating cascade is due to the nonlinear dependence of the mean blocking time of a single channel on the entering particle flux that more than compensates for the decrease in the number of active channels.

  14. Quantum Cascade Laser Frequency Combs

    CERN Document Server

    Faist, Jérôme; Scalari, Giacomo; Rösch, Markus; Bonzon, Christopher; Hugi, Andreas; Beck, Mattias

    2015-01-01

    It was recently demonstrated that broadband quantum cascade lasers can operate as frequency combs. As such, they operate under direct electrical pumping at both mid-infrared and THz frequencies, making them very attractive for dual-comb spectroscopy. Performance levels are continuously improving, with average powers over 100 mW and frequency coverage of 100 cm$^{-1}$ in the mid-infrared. In the THz range, 10 mW of average power and 600 GHz of frequency coverage are reported. As a result of the very short upper state lifetime of the gain medium, the mode proliferation in these sources arises from four wave mixing rather than saturable absorption. As a result, their optical output is characterized by the tendency of small intensity modulation of the output power, and the relative phases of the modes to be similar to the ones of a frequency modulated laser. Recent results include the proof of comb operation down to a metrological level, the observation of a Schawlow-Townes broadened linewidth, as well as the fir...

  15. Quantum Cascade Laser Frequency Combs

    Science.gov (United States)

    Faist, Jérôme; Villares, Gustavo; Scalari, Giacomo; Rösch, Markus; Bonzon, Christopher; Hugi, Andreas; Beck, Mattias

    2016-06-01

    It was recently demonstrated that broadband quantum cascade lasers can operate as frequency combs. As such, they operate under direct electrical pumping at both mid-infrared and THz frequencies, making them very attractive for dual-comb spectroscopy. Performance levels are continuously improving, with average powers over 100mW and frequency coverage of 100 cm-1 in the mid-infrared region. In the THz range, 10mW of average power and 600 GHz of frequency coverage are reported. As a result of the very short upper state lifetime of the gain medium, the mode proliferation in these sources arises from four-wave mixing rather than saturable absorption. As a result, their optical output is characterized by the tendency of small intensity modulation of the output power, and the relative phases of the modes to be similar to the ones of a frequency modulated laser. Recent results include the proof of comb operation down to a metrological level, the observation of a Schawlow-Townes broadened linewidth, as well as the first dual-comb spectroscopy measurements. The capability of the structure to integrate monothically nonlinear optical elements as well as to operate as a detector shows great promise for future chip integration of dual-comb systems.

  16. Aspects of the QCD cascade

    International Nuclear Information System (INIS)

    A model is proposed for the production of transverse jets from diffractively excited protons. We propose that transverse jets can be obtained from gluonic bremsstrahlung in a way similar to the emission in DIS. Qualitative agreement is obtained between the model and the uncorrected data published by the UA8 collaboration. Perturbative QCD in the MLLA approximation is applied to multiple jet production in e+e--annihilation. We propose modified evolution equations for deriving the jet cross sections, defined in the 'kt' or 'Durham' algorithm. The mean number of jets as a function of the jet resolution is studied, and analytical predictions are compared to the results of MC simulations. We also study a set of differential-difference equations for multiplicity distributions in e+e--annihilations, supplemented with appropriate boundary conditions. These equations take into account nonsingular terms in the GLAP splitting functions as well as kinematical constraints related to recoil effects. The presence of retarded terms imply that the cascade develops more slowly and reduces the fluctuations. The solutions agree well with MC simulations and experimental data. (authors)

  17. Bursting behaviours in cascaded stimulated Brillouin scattering

    Institute of Scientific and Technical Information of China (English)

    Liu Zhan-Jun; He Xian-Tu; Zheng Chun-Yang; Wang Yu-Gang

    2012-01-01

    Stimulated Brillouin scattering is studied by numerically solving the Vlasov-Maxwell system.A cascade of stimulated Brillouin scattering can occur when a linearly polarized laser pulse propagates in a plasma.It is found that a stimulated Brillouin scattering cascade can reduce the scattering and increase the transmission of light,as well as introduce a bursting behaviour in the evolution of the laser-plasma interaction.The bursting time in the reflectivity is found to be less than half the ion acoustic period.The ion temperature can affect the stimulated Brillouin scattering cascade,which can repeat several times at low ion temperatures and can be completely eliminated at high ion temperatures.For stimulated Brillouin scattering saturation,higher-harmonic generation and wave-wave interaction of the excited ion acoustic waves can restrict the amplitude of the latter.In addition,stimulated Brillouin scattering cascade can restrict the amplitude of the scattered light.

  18. Model for cascading failures in congested Internet

    Institute of Scientific and Technical Information of China (English)

    Jian WANG; Yan-heng LIU; Jian-qi ZHU; Yu JIAO

    2008-01-01

    Cascading failures often occur in congested networks such as the Internet. A cascading failure can be described as a three-phase process: generation, diffusion, and dissipation of the congestion. In this account, we present a function that represents the extent of congestion on a given node. This approach is different from existing functions based on betweenness centrality. By introducing the concept of 'delay time', we designate an intergradation between permanent removal and nouremoval. We also construct an evaluation function of network efficiency, based on congestion, which measures the damage caused by cascading failures. Finally, we investigate the effects of network structure and size, delay time, processing ability and packet generation speed on congestion propagation. Also, we uncover the relationship between the cascade dynamics and some properties of the network such as structure and size.

  19. Cascade Error Projection: A New Learning Algorithm

    Science.gov (United States)

    Duong, T. A.; Stubberud, A. R.; Daud, T.; Thakoor, A. P.

    1995-01-01

    A new neural network architecture and a hardware implementable learning algorithm is proposed. The algorithm, called cascade error projection (CEP), handles lack of precision and circuit noise better than existing algorithms.

  20. Chemoenzymatic cascade processes for sustainable organic synthesis

    NARCIS (Netherlands)

    Simons, C.

    2007-01-01

    Chemical production processes often require wasteful and expensive isolation as well as purification of intermediates. Catalytic cascades offer a unique opportunity to eliminate these inefficient and polluting steps, in particular when carefully orchestrated, involving enzymes and chemocatalysts. Th

  1. Network effects, cascades and CCP interoperability

    Science.gov (United States)

    Feng, Xiaobing; Hu, Haibo; Pritsker, Matthew

    2014-03-01

    To control counterparty risk, financial regulations such as the Dodd Frank Act are increasingly requiring standardized derivatives trades to be cleared by central counterparties (CCPs). It is anticipated that in the near-term future, CCPs across the world will be linked through interoperability agreements that facilitate risk-sharing but also serve as a conduit for transmitting shocks. This paper theoretically studies a network with CCPs that are linked through interoperability arrangements, and studies the properties of the network that contribute to cascading failures. The magnitude of the cascading is theoretically related to the strength of network linkages, the size of the network, the logistic mapping coefficient, a stochastic effect and CCP's defense lines. Simulations indicate that larger network effects increase systemic risk from cascading failures. The size of the network N raises the threshold value of shock sizes that are required to generate cascades. Hence, the larger the network, the more robust it will be.

  2. A quantum cascade phonon-polariton laser

    CERN Document Server

    Ohtani, Keita; Bosco, Lorenzo; Beck, Mattias; Faist, Jérôme

    2016-01-01

    We report a laser that coherently emits phonon-polaritons, quasi-particles arising from the coupling between photons and transverse optical phonons. The gain is provided by an intersubband transition in a quantum cascade structure. The polaritons at h$\

  3. Compression limits in cascaded quadratic soliton compression

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Krolikowski, Wieslaw;

    2008-01-01

    Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency.......Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency....

  4. Innovation cascades: artefacts, organization and attributions.

    Science.gov (United States)

    Lane, David A

    2016-03-19

    Innovation cascades inextricably link the introduction of new artefacts, transformations in social organization, and the emergence of new functionalities and new needs. This paper describes a positive feedback dynamic, exaptive bootstrapping, through which these cascades proceed, and the characteristics of the relationships in which the new attributions that drive this dynamic are generated. It concludes by arguing that the exaptive bootstrapping dynamic is the principal driver of our current Innovation Society.

  5. Simulation of cascades in W-He

    OpenAIRE

    Juslin, Niklas; Jansson, Ville Bernt Christian; Nordlund, Kai

    2010-01-01

    Abstract He will be present in fusion reactor wall materials, and its effect on radiation damage must be taken into account. The effect of helium on displacement cascades in tungsten has been studied using molecular dynamics simulations. Three different W--W potentials were compared and found to differ especially for the clustering of the vacancies formed in the cascades. While there are differences in the amounts of damage depending on the potential, the overa...

  6. Cascade Textures and SUSY SO(10) GUT

    CERN Document Server

    Adulpravitchai, Adisorn; Takahashi, Ryo

    2010-01-01

    We give texture analyses of cascade hierarchical mass matrices in supersymmetric SO(10) grand unified theory. We embed cascade mass textures of the standard model fermion with right-handed neutrinos into the theory, which gives relations among the mass matrices of the fermions. The related phenomenologies, such as the lepton flavor violating processes and leptogenesis, are also investigated in addition to the PMNS mixing angles.

  7. Emergence of event cascades in inhomogeneous networks

    Science.gov (United States)

    Onaga, Tomokatsu; Shinomoto, Shigeru

    2016-09-01

    There is a commonality among contagious diseases, tweets, and neuronal firings that past events facilitate the future occurrence of events. The spread of events has been extensively studied such that the systems exhibit catastrophic chain reactions if the interaction represented by the ratio of reproduction exceeds unity; however, their subthreshold states are not fully understood. Here, we report that these systems are possessed by nonstationary cascades of event-occurrences already in the subthreshold regime. Event cascades can be harmful in some contexts, when the peak-demand causes vaccine shortages, heavy traffic on communication lines, but may be beneficial in other contexts, such that spontaneous activity in neural networks may be used to generate motion or store memory. Thus it is important to comprehend the mechanism by which such cascades appear, and consider controlling a system to tame or facilitate fluctuations in the event-occurrences. The critical interaction for the emergence of cascades depends greatly on the network structure in which individuals are connected. We demonstrate that we can predict whether cascades may emerge, given information about the interactions between individuals. Furthermore, we develop a method of reallocating connections among individuals so that event cascades may be either impeded or impelled in a network.

  8. Forward and Inverse Cascades in EMHD Turbulence

    Science.gov (United States)

    Cho, Jungyeon

    2016-05-01

    Electron magnetohydrodynamics (EMHD) provides a simple fluid-like description of physics below the proton gyro-scale in collisionless plasmas, such as the solar wind. In this paper, we discuss forward and inverse cascades in EMHD turbulence in the presence of a strong mean magnetic field. Similar to Alfvén waves, EMHD waves, or EMHD perturbations, propagate along magnetic field lines. Therefore, two types of EMHD waves can exist: waves moving parallel to and waves moving anti-parallel to the the magnetic field lines. For energy cascade in EMHD turbulence, the relative amplitudes of opposite-traveling waves are important. When the amplitudes are balanced, we will see fully-developed forward cascade with a k -7/3 energy spectrum and a scale-dependent anisotropy. On the other hand, when the amplitudes are imbalanced, we will see inverse cascade, as well as (presumably not fully developed) forward cascade. The underlying physics for the inverse cascade is magnetic helicity conservation.

  9. Emergence of event cascades in inhomogeneous networks.

    Science.gov (United States)

    Onaga, Tomokatsu; Shinomoto, Shigeru

    2016-01-01

    There is a commonality among contagious diseases, tweets, and neuronal firings that past events facilitate the future occurrence of events. The spread of events has been extensively studied such that the systems exhibit catastrophic chain reactions if the interaction represented by the ratio of reproduction exceeds unity; however, their subthreshold states are not fully understood. Here, we report that these systems are possessed by nonstationary cascades of event-occurrences already in the subthreshold regime. Event cascades can be harmful in some contexts, when the peak-demand causes vaccine shortages, heavy traffic on communication lines, but may be beneficial in other contexts, such that spontaneous activity in neural networks may be used to generate motion or store memory. Thus it is important to comprehend the mechanism by which such cascades appear, and consider controlling a system to tame or facilitate fluctuations in the event-occurrences. The critical interaction for the emergence of cascades depends greatly on the network structure in which individuals are connected. We demonstrate that we can predict whether cascades may emerge, given information about the interactions between individuals. Furthermore, we develop a method of reallocating connections among individuals so that event cascades may be either impeded or impelled in a network. PMID:27625183

  10. Quantum Cascade Photonic Crystal lasers

    Science.gov (United States)

    Capasso, Federico

    2004-03-01

    QC lasers have emerged in recent years as the dominant laser technology for the mid-to far infrared spectrum in light of their room temperature operation, their tunability, ultrahigh speed operation and broad range of applications to chemical sensing, spectroscopy etc. (Ref. 1-3). After briefly reviewing the latter, I will describe a new class of mid-infrared QC lasers, Quantum Cascade Photonic Crystal Surface Emitting Lasers (QCPCSELS), that combine electronic and photonic band structure engineering to achieve vertical emission from the surface (Ref. 4). Devices operating on bandedge mode and on defect modes will be discussed. Exciting potential uses of these new devices exist in nonlinear optics, microfluidics as well as novel sensors. Finally a bird's eye view of other exciting areas of QC laser research will be given including broadband QCLs and new nonlinear optical sources based on multiwavelength QCLs. 1. F. Capasso, C. Gmachl, D. L. Sivco, and A. Y. Cho, Physics Today 55, 34 (May 2002) 2. F. Capasso, C. Gmachl, R. Paiella, A. Tredicucci, A. L. Hutchinson, D. L. Sivco, J. N. Baillargeon, A. Y. Cho and H. C. Liu, IEEE Journal of Selected Topics in Quantum Electronics, 6, 931 (2000). 3. F. Capasso, R. Paiella, R. Martini, R. Colombelli, C. Gmachl, T. L. Myers, M. S. Taubman, R. M. Williams, C. G. Bethea, K. Unterrainer, H. Y. Hwang, D. L. Sivco, A. Y. Cho, A. M. Sergent, H. C. Liu, E. A. Whittaker, IEEE J. Quantum Electron. 38, 511 (2002) 4. R. Colombelli, K. Srivasan, M. Troccoli, O. Painter, C. Gmachl, D. M. Tennant, A. M. Sergent, D. L. Sivco, A. Y. Cho and F. Capasso, Science 302, 1374 (2003)

  11. ELMAG: A Monte Carlo simulation of electromagnetic cascades on the extragalactic background light and in magnetic fields

    CERN Document Server

    Kachelriess, M; Tomas, R

    2011-01-01

    A Monte Carlo program for the simulation of electromagnetic cascades initiated by high-energy photons and electrons interacting with extragalactic background light (EBL) is presented. Pair production and inverse Compton scattering on EBL photons as well as synchrotron losses and deflections of the charged component in extragalactic magnetic fields (EGMF) are included in the simulation. Weighted sampling of the cascade development is applied to reduce the number of secondary particles and to speed up computations. As final result, the simulation procedure provides the energy, the observation angle, and the time delay of secondary cascade particles at the present epoch. Possible applications are the study of TeV blazars and the influence of the EGMF on their spectra or the calculation of the contribution from ultrahigh energy cosmic rays or dark matter to the diffuse extragalactic gamma-ray background. As an illustration, we present results for deflections and time-delays relevant for the derivation of limits o...

  12. A Monte Carlo Simulation of Prompt Gamma Emission from Fission Fragments

    Directory of Open Access Journals (Sweden)

    Litaize O.

    2013-03-01

    Full Text Available The prompt fission gamma spectra and multiplicities are investigated through the Monte Carlo code FIFRELIN which is developed at the Cadarache CEA research center. Knowing the fully accelerated fragment properties, their de-excitation is simulated through a cascade of neutron, gamma and/or electron emissions. This paper presents the recent developments in the FIFRELIN code and the results obtained on the spontaneous fission of 252Cf. Concerning the decay cascades simulation, a fully Hauser-Feshbach model is compared with a previous one using a Weisskopf spectrum for neutron emission. A particular attention is paid to the treatment of the neutron/gamma competition. Calculations lead using different level density and gamma strength function models show significant discrepancies of the slope of the gamma spectra at high energy. The underestimation of the prompt gamma spectra obtained regardless our de-excitation cascade modeling choice is discussed. This discrepancy is probably linked to an underestimation of the post-neutron fragments spin in our calculation.

  13. Harmonic cascade FEL designs for LUX

    Energy Technology Data Exchange (ETDEWEB)

    Penn, G.; Reinsch, M.; Wurtele, J.; Corlett, J.N.; Fawley, W.M.; Zholents, A.; Wan, W.

    2004-07-16

    LUX is a design concept for an ultrafast X-ray science facility, based on an electron beam accelerated to GeV energies in are circulating linac. Included in the design are short duration (200 fs or shorter FWHM) light sources using multiple stages of higher harmonic generation, seeded by a 200-250 nm laser of similar duration. This laser modulates the energy of a group of electrons within the electron bunch; this section of the electron bunch then produces radiation at a higher harmonic after entering a second, differently tuned undulator. Repeated stages in a cascade yield increasing photon energies up to 1 keV. Most of the undulators in the cascade operate in the low-gain FEL regime. Harmonic cascades have been designed for each pass of the recirculating linac up to a final electron beam energy of 3.1 GeV. For a given cascade, the photon energy can be selected over a wide range by varying the seed laser frequency and the field strength in the undulators. We present simulation results using the codes GENESIS and GINGER, as well as the results of analytical models which predict FEL performance. We discuss lattice considerations pertinent for harmonic cascade FELs, as well as sensitivity studies and requirements on the electron beam.

  14. A new method in gamma-ray spectroscopy: A two crystal scintillation spectrometer with improved resolution

    NARCIS (Netherlands)

    Hoogenboom, A.M.

    1958-01-01

    A new method has been developed to measure the spectra of gamma radiation emitted in cascade disintegrations. Use is made of a two-crystal scintillation spectrometer and a gated multi-channel analysing device. The pulses produced by summing the outputs of the two crystal-photomultiplier combinations

  15. High Energy $\\gamma$ Rays from Ultrahigh Energy Cosmic Ray Protons in $\\gamma$ Ray Bursts

    CERN Document Server

    Böttcher, M

    1998-01-01

    It has recently been proposed that ultrahigh energy ($\\gtrsim 10^{19}$ eV) cosmic rays (UHECR) are accelerated by the blast waves associated with GRBs. We calculate the observed synchrotron radiation spectrum from protons and energetic leptons formed in the cascades initiated by photopion production, taking into account $\\gamma\\gamma$ attenuation at the source. Normalizing to the emission characteristics of GRB~970508, we predict $\\sim 10$ MeV - 100 GeV fluxes at a level which may have been observed with EGRET from bright GRBs, and could be detected with the proposed GLAST experiment or with ground-based air Cherenkov telescopes having thresholds $\\lesssim $ several hundred GeV. Besides testing the UHECR origin hypothesis, the short wavelength emission and afterglows can be used to probe the level of the diffuse intergalactic infrared radiation fields or constrain redshifts of GRB sources.

  16. Bifurcations analysis of turbulent energy cascade

    Energy Technology Data Exchange (ETDEWEB)

    Divitiis, Nicola de, E-mail: n.dedivitiis@gmail.com

    2015-03-15

    This note studies the mechanism of turbulent energy cascade through an opportune bifurcations analysis of the Navier–Stokes equations, and furnishes explanations on the more significant characteristics of the turbulence. A statistical bifurcations property of the Navier–Stokes equations in fully developed turbulence is proposed, and a spatial representation of the bifurcations is presented, which is based on a proper definition of the fixed points of the velocity field. The analysis first shows that the local deformation can be much more rapid than the fluid state variables, then explains the mechanism of energy cascade through the aforementioned property of the bifurcations, and gives reasonable argumentation of the fact that the bifurcations cascade can be expressed in terms of length scales. Furthermore, the study analyzes the characteristic length scales at the transition through global properties of the bifurcations, and estimates the order of magnitude of the critical Taylor-scale Reynolds number and the number of bifurcations at the onset of turbulence.

  17. MAP Kinase Cascades in Plant Innate Immunity

    Directory of Open Access Journals (Sweden)

    Magnus Wohlfahrt Rasmussen

    2012-07-01

    Full Text Available Plant mitogen-activated protein kinase (MAPK cascades generally transduce extracellular stimuli into cellular responses. These stimuli include the perception of pathogen-associated molecular patterns (PAMPs by host transmembrane pattern recognition receptors (PRRs which trigger MAPK-dependent innate immune responses. In the model Arabidopsis, molecular genetic evidence implicates a number of MAPK cascade components in PAMP signaling, and in responses to immunity-related phytohormones such as ethylene, jasmonate and salicylate. In a few cases, cascade components have been directly linked to the transcription of target genes or to the regulation of phytohormone synthesis. Thus MAPKs are obvious targets for bacterial effector proteins and are likely guardees of resistance (R proteins, which mediate defense signaling in response to the action of effectors, or effector-triggered immunity (ETI. This mini-review discusses recent progress in this field with a focus on the Arabidopsis MAPKs MPK3, 4, 6 and 11 in their apparent pathways.

  18. Epidemic and Cascading Survivability of Complex Networks

    CERN Document Server

    Manzano, Marc; Ripoll, Jordi; Fagertun, Anna Manolova; Torres-Padrosa, Victor; Pahwa, Sakshi; Scoglio, Caterina

    2014-01-01

    Our society nowadays is governed by complex networks, examples being the power grids, telecommunication networks, biological networks, and social networks. It has become of paramount importance to understand and characterize the dynamic events (e.g. failures) that might happen in these complex networks. For this reason, in this paper, we propose two measures to evaluate the vulnerability of complex networks in two different dynamic multiple failure scenarios: epidemic-like and cascading failures. Firstly, we present \\emph{epidemic survivability} ($ES$), a new network measure that describes the vulnerability of each node of a network under a specific epidemic intensity. Secondly, we propose \\emph{cascading survivability} ($CS$), which characterizes how potentially injurious a node is according to a cascading failure scenario. Then, we show that by using the distribution of values obtained from $ES$ and $CS$ it is possible to describe the vulnerability of a given network. We consider a set of 17 different compl...

  19. Emergence of event cascades in inhomogeneous networks

    CERN Document Server

    Onaga, Tomokatsu

    2016-01-01

    There is a commonality among contagious diseases, tweets, urban crimes, nuclear reactions, and neuronal firings that past events facilitate the future occurrence of events. The spread of events has been extensively studied such that the systems exhibit catastrophic chain reactions if the interaction represented by the ratio of reproduction exceeds unity; however, their subthreshold states for the case of the weaker interaction are not fully understood. Here, we report that these systems are possessed by nonstationary cascades of event-occurrences already in the subthreshold regime. Event cascades can be harmful in some contexts, when the peak-demand causes vaccine shortages, heavy traffic on communication lines, frequent crimes, or large fluctuations in nuclear reactions, but may be beneficial in other contexts, such that spontaneous activity in neural networks may be used to generate motion or store memory. Thus it is important to comprehend the mechanism by which such cascades appear, and consider controlli...

  20. Cascade enzymatic reactions for efficient carbon sequestration.

    Science.gov (United States)

    Xia, Shunxiang; Zhao, Xueyan; Frigo-Vaz, Benjamin; Zheng, Wenyun; Kim, Jungbae; Wang, Ping

    2015-04-01

    Thermochemical processes developed for carbon capture and storage (CCS) offer high carbon capture capacities, but are generally hampered by low energy efficiency. Reversible cascade enzyme reactions are examined in this work for energy-efficient carbon sequestration. By integrating the reactions of two key enzymes of RTCA cycle, isocitrate dehydrogenase and aconitase, we demonstrate that intensified carbon capture can be realized through such cascade enzymatic reactions. Experiments show that enhanced thermodynamic driving force for carbon conversion can be attained via pH control under ambient conditions, and that the cascade reactions have the potential to capture 0.5 mol carbon at pH 6 for each mole of substrate applied. Overall it manifests that the carbon capture capacity of biocatalytic reactions, in addition to be energy efficient, can also be ultimately intensified to approach those realized with chemical absorbents such as MEA. PMID:25708541

  1. Search for Extended {\\gamma}-ray Emission around AGN with H.E.S.S. and Fermi-LAT

    CERN Document Server

    Abramowski, A; Benkhali, F Ait; Akhperjanian, A G; Angüner, E; Anton, G; Backes, M; Balenderan, S; Balzer, A; Barnacka, A; Becherini, Y; Tjus, J Becker; Bernlöhr, K; Birsin, E; Bissaldi, E; Biteau, J; Böttcher, M; Boisson, C; Bolmont, J; Bordas, P; Brucker, J; Brun, F; Brun, P; Bulik, T; Carrigan, S; Casanova, S; Chadwick, P M; Chalme-Calvet, R; Chaves, R C G; Cheesebrough, A; Chrétien, M; Colafrancesco, S; Cologna, G; Conrad, J; Couturier, C; Cui, Y; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; deWilt, P; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubus, G; Dutson, K; Dyks, J; Dyrda, M; Edwards, T; Egberts, K; Eger, P; Espigat, P; Farnier, C; Fegan, S; Feinstein, F; Fernandes, M V; Fernandez, D; Fiasson, A; Fontaine, G; Förster, A; Füßling, M; Gajdus, M; Gallant, Y A; Garrigoux, T; Giavitto, G; Giebels, B; Glicenstein, J F; Grondin, M -H; Grudzińska, M; Häffner, S; Hahn, J; Harris, J; Heinzelmann, G; Henri, G; Hermann, G; Hervet, O; Hillert, A; Hinton, J A; Hofmann, W; Hofverberg, P; Holler, M; Horns, D; Jacholkowska, A; Jahn, C; Jamrozy, M; Janiak, M; Jankowsky, F; Jung, I; Kastendieck, M A; Katarzyński, K; Katz, U; Kaufmann, S; Khélifi, B; Kieffer, M; Klepser, S; Klochkov, D; Kluźniak, W; Kneiske, T; Kolitzus, D; Komin, Nu; Kosack, K; Krakau, S; Krayzel, F; Krüger, P P; Laffon, H; Lamanna, G; Lefaucheur, J; Lemière, A; Lemoine-Goumard, M; Lenain, J -P; Lohse, T; Lopatin, A; Lu, C -C; Marandon, V; Marcowith, A; Marx, R; Maurin, G; Maxted, N; Mayer, M; McComb, T J L; Méhault, J; Meintjes, P J; Menzler, U; Meyer, M; Moderski, R; Mohamed, M; Moulin, E; Murach, T; Naumann, C L; de Naurois, M; Niemiec, J; Nolan, S J; Oakes, L; Odaka, H; Ohm, S; Wilhelmi, E de Oña; Opitz, B; Ostrowski, M; Oya, I; Panter, M; Parsons, R D; Arribas, M Paz; Pekeur, N W; Pelletier, G; Perez, J; Petrucci, P -O; Peyaud, B; Pita, S; Poon, H; Pühlhofer, G; Punch, M; Quirrenbach, A; Raab, S; Raue, M; Reichardt, I; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Rob, L; Romoli, C; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Sahakian, V; Sanchez, D A; Santangelo, A; Schlickeiser, R; Schüssler, F; Schulz, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Sol, H; Spengler, G; Spies, F; Stawarz, Ł; Steenkamp, R; Stegmann, C; Stinzing, F; Stycz, K; Sushch, I; Tavernet, J -P; Tavernier, T; Taylor, A M; Terrier, R; Tluczykont, M; Trichard, C; Valerius, K; van Eldik, C; van Soelen, B; Vasileiadis, G; Venter, C; Viana, A; Vincent, P; Völk, H J; Volpe, F; Vorster, M; Vuillaume, T; Wagner, S J; Wagner, P; Ward, M; Weidinger, M; Weitzel, Q; White, R; Wierzcholska, A; Willmann, P; Wörnlein, A; Wouters, D; Yang, R; Zabalza, V; Zacharias, M; Zdziarski, A A; Zech, A; Zechlin, H -S; Malyshev, D

    2014-01-01

    Context: Very-high-energy (VHE; E>100 GeV) {\\gamma}-ray emission from blazars inevitably gives rise to electron-positron pair production through the interaction of these {\\gamma}-rays with the Extragalactic Background Light (EBL). Depending on the magnetic fields in the proximity of the source, the cascade initiated from pair production can result in either an isotropic halo around an initially beamed source or a magnetically broadened cascade flux. Aims: Both extended pair halo (PH) and magnetically broadened cascade (MBC) emission from regions surrounding the blazars 1ES 1101-232, 1ES 0229+200 and PKS 2155-304 were searched for, using VHE {\\gamma}-ray data taken with the High Energy Stereoscopic System (H.E.S.S.), and high energy (HE; 100 MeV 10$^{-12}$G, this limits the production of pair halos developing from electromagnetic cascades. For weaker magnetic fields, in which electromagnetic cascades would result in magnetically broadened cascades, EGMF strengths in the range (0.3 - 3)$\\times 10^{-15}$G were e...

  2. Piscivores, Trophic Cascades, and Lake Management

    Directory of Open Access Journals (Sweden)

    Ray W. Drenner

    2002-01-01

    Full Text Available The concept of cascading trophic interactions predicts that an increase in piscivore biomass in lakes will result in decreased planktivorous fish biomass, increased herbivorous zooplankton biomass, and decreased phytoplankton biomass. Though often accepted as a paradigm in the ecological literature and adopted by lake managers as a basis for lake management strategies, the trophic cascading interactions hypothesis has not received the unequivocal support (in the form of rigorous experimental testing that might be expected of a paradigm. Here we review field experiments and surveys, testing the hypothesis that effects of increasing piscivore biomass will cascade down through the food web yielding a decline in phytoplankton biomass. We found 39 studies in the scientific literature examining piscivore effects on phytoplankton biomass. Of the studies, 22 were confounded by supplemental manipulations (e.g., simultaneous reduction of nutrients or removal of planktivores and could not be used to assess piscivore effects. Of the 17 nonconfounded studies, most did not find piscivore effects on phytoplankton biomass and therefore did not support the trophic cascading interactions hypothesis. However, the trophic cascading interactions hypothesis also predicts that lake systems containing piscivores will have lower phytoplankton biomass for any given phosphorus concentration. Based on regression analyses of chlorophyll�total phosphorus relationships in the 17 nonconfounded piscivore studies, this aspect of the trophic cascading interactions hypothesis was supported. The slope of the chlorophyll vs. total phosphorus regression was lower in lakes with planktivores and piscivores compared with lakes containing only planktivores but no piscivores. We hypothesize that this slope can be used as an indicator of “functional piscivory” and that communities with extremes of functional piscivory (zero and very high represent classical 3- and 4-trophic level

  3. Dynamics of Soliton Cascades in Fiber Amplifiers

    CERN Document Server

    Arteaga-Sierra, F R; Agrawal, Govind P

    2016-01-01

    We study numerically the formation of cascading solitons when femtosecond optical pulses are launched into a fiber amplifier with less energy than required to form a soliton of equal duration. As the pulse is amplified, cascaded fundamental solitons are created at different distances, without soliton fission, as each fundamental soliton moves outside the gain bandwidth through the Raman-induced spectral shifts. As a result, each input pulse creates multiple, temporally separated, ultrashort pulses of different wavelengths at the amplifier output. The number of pulses depends not only on the total gain of the amplifier but also on the width of input pulses.

  4. Energy cascade in internal wave attractors

    CERN Document Server

    Brouzet, Christophe; Joubaud, Sylvain; Sibgatullin, Ilias; Dauxois, Thierry

    2016-01-01

    One of the pivotal questions in the dynamics of the oceans is related to the cascade of mechanical energy in the abyss and its contribution to mixing. Here, we propose internal wave attractors in the large amplitude regime as a unique self-consistent experimental and numerical setup that models a cascade of triadic interactions transferring energy from large-scale monochro-matic input to multi-scale internal wave motion. We also provide signatures of a discrete wave turbulence framework for internal waves. Finally, we show how beyond this regime, we have a clear transition to a regime of small-scale high-vorticity events which induce mixing. Introduction.

  5. Rehabilitation of gamma

    Science.gov (United States)

    Poynton, Charles A.

    1998-07-01

    Gamma characterizes the reproduction of tone scale in an imaging system. Gamma summarizes, in a single numerical parameter, the nonlinear relationship between code value--in an 8-bit system, from 0 through 255--and physical intensity. Nearly all image coding systems are nonlinear, and so involve values of gamma different from unity. Owing to poor understanding of tone scale reproduction, and to misconceptions about nonlinear coding, gamma has acquired a terrible reputation in computer graphics and image processing. In addition, the world-wide web suffers from poor reproduction of grayscale and color images, due to poor handling of nonlinear image coding. This paper aims to make gamma respectable again.

  6. Reactor gamma spectrometry: status

    International Nuclear Information System (INIS)

    Current work is described for Compton Recoil Gamma-Ray Spectrometry including developments in experimental technique as well as recent reactor spectrometry measurements. The current status of the method is described concerning gamma spectromoetry probe design and response characteristics. Emphasis is given to gamma spectrometry work in US LWR and BR programs. Gamma spectrometry in BR environments are outlined by focussing on start-up plans for the Fast Test Reactor (FTR). Gamma spectrometry results are presented for a LWR pressure vessel mockup in the Poolside Critical Assembly (PCA) at Oak Ridge National Laboratory

  7. Habitat cascades: the conceptual context and global relevance of facilitation cascades via habitat formation and modification.

    Science.gov (United States)

    Thomsen, Mads S; Wernberg, Thomas; Altieri, Andrew; Tuya, Fernando; Gulbransen, Dana; McGlathery, Karen J; Holmer, Marianne; Silliman, Brian R

    2010-08-01

    The importance of positive interactions is increasingly acknowledged in contemporary ecology. Most research has focused on direct positive effects of one species on another. However, there is recent evidence that indirect positive effects in the form of facilitation cascades can also structure species abundances and biodiversity. Here we conceptualize a specific type of facilitation cascade-the habitat cascade. The habitat cascade is defined as indirect positive effects on focal organisms mediated by successive facilitation in the form of biogenic formation or modification of habitat. Based on a literature review, we demonstrate that habitat cascades are a general phenomenon that enhances species abundance and diversity in forests, salt marshes, seagrass meadows, and seaweed beds. Habitat cascades are characterized by a hierarchy of facilitative interactions in which a basal habitat former (typically a large primary producer, e.g., a tree) creates living space for an intermediate habitat former (e.g., an epiphyte) that in turn creates living space for the focal organisms (e.g., spiders, beetles, and mites). We then present new data on a habitat cascade common to soft-bottom estuaries in which a relatively small invertebrate provides basal habitat for larger intermediate seaweeds that, in turn, generate habitat for focal invertebrates and epiphytes. We propose that indirect positive effects on focal organisms will be strongest when the intermediate habitat former is larger and different in form and function from the basal habitat former. We also discuss how humans create, modify, and destroy habitat cascades via global habitat destruction, climatic change, over-harvesting, pollution, or transfer of invasive species. Finally, we outline future directions for research that will lead to a better understanding of habitat cascades. PMID:21558196

  8. Ultrahigh Energy Cosmic Rays, The Diffuse High Energy Gamma Ray Background and Anti-protons

    OpenAIRE

    Eichler, David; Idan, Raz; Gavish, Eyal

    2016-01-01

    Theories for the origin of ultrahigh energy cosmic rays (UHECR) may imply a significant diffuse background in secondary $\\gamma$-rays from the pair cascads the UHECR initiate when interacting with background light. It is shown that, because the spectrum of these secondary $\\gamma$-rays is softer than the measured diffuse $\\gamma$-ray background in the 10-1000 GeV range, the addition of a hard component from the decay of TeV dark matter particles, subject to the implied constraints on its para...

  9. GammaWorkshops Proceedings

    DEFF Research Database (Denmark)

    Strålberg, Elisabeth; Klemola, Seppo; Nielsen, Sven Poul;

    Due to a sparse interaction during the last years between practioners in gamma ray spectrometry in the Nordic countries, a NKS activity was started in 2009. This GammaSem was focused on seminars relevant to gamma spectrometry. A follow up seminar was held in 2010. As an outcome of these activities...... it was suggested that the 2011 meeting should be focused on practical issues, e.g. different corrections needed in gamma spectrometric measurements. This three day’s meeting, GammaWorkshops, was held in September at Risø-DTU. Experts on different topics relevant for gamma spectrometric measurements were invited...... to the GammaWorkshops. The topics included efficiency transfer, true coincidence summing corrections, self-attenuation corrections, measurement of natural radionuclides (natural decay series), combined measurement uncertainty calculations, and detection limits. These topics covered both lectures and practical...

  10. Metamaterials for novel X- or gamma-ray detector designs

    CERN Document Server

    Lecoq, P

    2009-01-01

    In the majority of X and gamma ray conversion detector heads there is generally a trade-off between the spatial and the energy resolution, as a good spatial resolution requires a high segmentation whereas a good energy resolution is obtained in a large enough detector volume to contain all the cascade interactions generated by the incoming particle. The quest for better spatial resolution in all three dimensions for the majority of applications (High-energy physics and particle detectors, Spectrometry of low energy gamma-quanta, Medical imaging, Homeland security, Space applications) may lead to a huge increase of the number of readout channels, with all the associated problems of connectivity, detector integration and heat dissipation. This paper explores the potential of recent progress in the field of crystallogenesis, quantum dots and photonics crystals towards a new concept of X- and gamma-ray detector based on metamaterials to simultaneously record with high precision the maximum of information of the c...

  11. Defect accumulation under cascade damage conditions

    DEFF Research Database (Denmark)

    Trinkaus, H.; Singh, B.N.; Woo, C.H.

    1994-01-01

    discussed in terms of this reaction kinetics taking into account cluster production, dissociation, migration and annihilation at extended sinks. Microstructural features which are characteristic of cascade damage and cannot be explained in terms of the conventional single defect reaction kinetics are...

  12. Nested Canalyzing, Unate Cascade, and Polynomial Functions.

    Science.gov (United States)

    Jarrah, Abdul Salam; Raposa, Blessilda; Laubenbacher, Reinhard

    2007-09-15

    This paper focuses on the study of certain classes of Boolean functions that have appeared in several different contexts. Nested canalyzing functions have been studied recently in the context of Boolean network models of gene regulatory networks. In the same context, polynomial functions over finite fields have been used to develop network inference methods for gene regulatory networks. Finally, unate cascade functions have been studied in the design of logic circuits and binary decision diagrams. This paper shows that the class of nested canalyzing functions is equal to that of unate cascade functions. Furthermore, it provides a description of nested canalyzing functions as a certain type of Boolean polynomial function. Using the polynomial framework one can show that the class of nested canalyzing functions, or, equivalently, the class of unate cascade functions, forms an algebraic variety which makes their analysis amenable to the use of techniques from algebraic geometry and computational algebra. As a corollary of the functional equivalence derived here, a formula in the literature for the number of unate cascade functions provides such a formula for the number of nested canalyzing functions.

  13. Impedance interactions in bidirectional cascaded converter

    DEFF Research Database (Denmark)

    Tian, Yanjun; Loh, Poh Chiang; Chen, Zhe;

    2016-01-01

    here for showing that forward and reverse interactions are prominently different in terms of dynamics and stability, even though the cascaded converter control remains unchanged. The concluded findings have been verified by simulation and experimental results, from which, important guidelines have been...

  14. Modeling and simulation of cascading contingencies

    Science.gov (United States)

    Zhang, Jianfeng

    This dissertation proposes a new approach to model and study cascading contingencies in large power systems. The most important contribution of the work involves the development and validation of a heuristic analytic model to assess the likelihood of cascading contingencies, and the development and validation of a uniform search strategy. We model the probability of cascading contingencies as a function of power flow and power flow changes. Utilizing logistic regression, the proposed model is calibrated using real industry data. This dissertation analyzes random search strategies for Monte Carlo simulations and proposes a new uniform search strategy based on the Metropolis-Hastings Algorithm. The proposed search strategy is capable of selecting the most significant cascading contingencies, and it is capable of constructing an unbiased estimator to provide a measure of system security. This dissertation makes it possible to reasonably quantify system security and justify security operations when economic concerns conflict with reliability concerns in the new competitive power market environment. It can also provide guidance to system operators about actions that may be taken to reduce the risk of major system blackouts. Various applications can be developed to take advantage of the quantitative security measures provided in this dissertation.

  15. Cascading effects of overfishing marine systems

    NARCIS (Netherlands)

    Scheffer, M.; Carpenter, S.; Young, de B.

    2005-01-01

    Profound indirect ecosystem effects of overfishing have been shown for coastal systems such as coral reefs and kelp forests. A new study from the ecosystem off the Canadian east coast now reveals that the elimination of large predatory fish can also cause marked cascading effects on the pelagic food

  16. Quantum-engineered interband cascade photovoltaic devices

    Science.gov (United States)

    Yang, Rui Q.; Lotfi, Hossein; Li, Lu; Hinkey, Robert T.; Ye, Hao; Klem, John F.; Lei, L.; Mishima, T. D.; Keay, J. C.; Santos, M. B.; Johnson, M. B.

    2013-12-01

    Quantum-engineered multiple stage photovoltaic (PV) devices are explored based on InAs/GaSb/AlSb interband cascade (IC) structures. These ICPV devices employ multiple discrete absorbers that are connected in series by widebandgap unipolar barriers using type-II heterostructure interfaces for facilitating carrier transport between cascade stages similar to IC lasers. The discrete architecture is beneficial for improving the collection efficiency and for spectral splitting by utilizing absorbers with different bandgaps. As such, the photo-voltages from each individual cascade stage in an ICPV device add together, creating a high overall open-circuit voltage, similar to conventional multi-junction tandem solar cells. Furthermore, photo-generated carriers can be collected with nearly 100% efficiency in each stage. This is because the carriers travel over only a single cascade stage, designed to be shorter than a typical diffusion length. The approach is of significant importance for operation at high temperatures where the diffusion length is reduced. Here, we will present our recent progress in the study of ICPV devices, which includes the demonstration of ICPV devices at room temperature and above with narrow bandgaps (e.g. 0.23 eV) and high open-circuit voltages.

  17. Cascaded frequency doublers for broadband laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, N F; Vlasova, K V; Davydov, V S; Kulikov, S M; Makarov, A I; Sukharev, Stanislav A; Freidman, Gennadii I; Shubin, S V

    2012-10-31

    A new scheme of a cascaded converter of the first harmonic of broadband cw laser radiation into the second harmonic (SH) with compensation for the group walk-off in cascades is proposed and investigated. The conditions under which high conversion coefficients of broadband ({approx}33 cm{sup -1}) single-mode fibre laser radiation with low peak power ({approx}300 W) into the SH are determined for frequency doublers based on the most promising LBO crystal. Conversion of cw radiation with an average power of 300 W and efficiency {eta} = 4.5 % into the SH is obtained in a single LBO crystal. Effect of coherent addition of SH radiation excited in different cascades is demonstrated for two- and three-stage schemes. The expected conversion efficiencies, calculated disregarding loss but taking into account real aberrations of elements, are 18 % and 38 %, respectively. The effect of pumping depletion begins to manifest itself in the third cascade of a three-stage converter; it may reduce the latter value to {approx}30 %. (nonlinear optical phenomena)

  18. Cascaded frequency doublers for broadband laser radiation

    Science.gov (United States)

    Andreev, N. F.; Vlasova, K. V.; Davydov, V. S.; Kulikov, S. M.; Makarov, A. I.; Sukharev, Stanislav A.; Freidman, Gennadii I.; Shubin, S. V.

    2012-10-01

    A new scheme of a cascaded converter of the first harmonic of broadband cw laser radiation into the second harmonic (SH) with compensation for the group walk-off in cascades is proposed and investigated. The conditions under which high conversion coefficients of broadband (~33 cm-1) single-mode fibre laser radiation with low peak power (~300 W) into the SH are determined for frequency doublers based on the most promising LBO crystal. Conversion of cw radiation with an average power of 300 W and efficiency η = 4.5 % into the SH is obtained in a single LBO crystal. Effect of coherent addition of SH radiation excited in different cascades is demonstrated for two- and three-stage schemes. The expected conversion efficiencies, calculated disregarding loss but taking into account real aberrations of elements, are 18 % and 38 %, respectively. The effect of pumping depletion begins to manifest itself in the third cascade of a three-stage converter; it may reduce the latter value to ~30 %.

  19. Geothermal research, Oregon Cascades: Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Priest, G.R.; Black, G.L.

    1988-10-27

    Previous USDOE-funded geothermal studies have produced an extensive temperature gradient and heat flow data base for the State of Oregon. One of the important features identified as a result of these studies is a rapid transition from heat flow values on the order of 40 mW/m/sup 2/ in the Willamette Valley and Western Cascades to values of greater than or equal to100 mW/m/sup 2/ in the High Cascades and the eastern portion of the Western Cascades. These data indicate that the Cascade Range in Oregon has potential as a major geothermal province and stimulated much of the later work completed by government agencies and private industry. Additional data generated as a result of this grant and published in DOGAMI Open-File Report 0-86-2 further define the location and magnitude of this transition zone. In addition, abundant data collected from the vicinity of Breitenbush and Austin Hot Springs have permitted the formulation of relatively detailed models of these hydrothermal systems. These models are published in DOGAMI Open-File Report 0-88-5. Task 1.2 of the Deliverables section of Amendment M001 is fulfilled by DOGAMI publication GMS-48, Geologic map of the McKenzie Bridge quadrangle, Lane County, Oregon. This map was printed in October, 1988, and is part of the final submission to USDOE. 8 refs.

  20. Forecasting Social Unrest Using Activity Cascades.

    Science.gov (United States)

    Cadena, Jose; Korkmaz, Gizem; Kuhlman, Chris J; Marathe, Achla; Ramakrishnan, Naren; Vullikanti, Anil

    2015-01-01

    Social unrest is endemic in many societies, and recent news has drawn attention to happenings in Latin America, the Middle East, and Eastern Europe. Civilian populations mobilize, sometimes spontaneously and sometimes in an organized manner, to raise awareness of key issues or to demand changes in governing or other organizational structures. It is of key interest to social scientists and policy makers to forecast civil unrest using indicators observed on media such as Twitter, news, and blogs. We present an event forecasting model using a notion of activity cascades in Twitter (proposed by Gonzalez-Bailon et al., 2011) to predict the occurrence of protests in three countries of Latin America: Brazil, Mexico, and Venezuela. The basic assumption is that the emergence of a suitably detected activity cascade is a precursor or a surrogate to a real protest event that will happen "on the ground." Our model supports the theoretical characterization of large cascades using spectral properties and uses properties of detected cascades to forecast events. Experimental results on many datasets, including the recent June 2013 protests in Brazil, demonstrate the effectiveness of our approach. PMID:26091012

  1. Spectra of {gamma} rays feeding superdeformed bands

    Energy Technology Data Exchange (ETDEWEB)

    Lauritsen, T.; Khoo, T.L.; Henry, R.G. [and others

    1995-08-01

    The spectrum of {gamma}rays coincident with SD transitions contains the transitions which populate the SD band. This spectrum can provide information on the feeding mechanism and on the properties (moment of inertia, collectivity) of excited SD states. We used a model we developed to explain the feeding of SD bands, to calculate the spectrum of feeding {gamma}rays. The Monte Carlo simulations take into account the trigger conditions present in our Eurogam experiment. Both experimental and theoretical spectra contain a statistical component and a broad E2 peak (from transitions occurring between excited states in the SD well). There is good resemblance between the measured and calculated spectra although the calculated multiplicity of an E2 bump is low by {approximately}30%. Work is continuing to improve the quality of the fits, which will result in a better understanding of excited SD states. In addition, a model for the last steps, which cool the {gamma} cascade into the SD yrast line, needs to be developed. A strong M1/E2 low-energy component, which we believe is responsible for this cooling, was observed.

  2. Cascades with coupled map lattices in preferential attachment community networks

    Institute of Scientific and Technical Information of China (English)

    Cui Di; Gao Zi-You; Zhao Xiao-Mei

    2008-01-01

    In this paper,cascading failure is studied by coupled map lattice (CML) methods in preferential attachment community networks.It is found that external perturbation R is increasing with modularity Q growing by simulation.In particular,the large modularity Q can hold off the cascading failure dynamic process in community networks.Furthermore,different attack strategies also greatly affect the cascading failure dynamic process. It is particularly significant to control cascading failure process in real community networks.

  3. Optimization Control of Bidirectional Cascaded DC-AC Converter Systems

    DEFF Research Database (Denmark)

    Tian, Yanjun

    in bidirectional cascaded converter. This research work analyses the control strategies based on the topology of dual active bridges converter cascaded with a three phase inverter. It firstly proposed a dc link voltage and active power coordinative control method for this cascaded topology, and it can reduce dc...

  4. Z-Scan Characteristics of Cascading Nonlinear Media

    Institute of Scientific and Technical Information of China (English)

    臧维平; 田建国; 刘智波; 周文远; 杨新江; 张春平; 张光寅

    2003-01-01

    We present a method, which combines the Gaussian decomposition method and the "distributed-lens" method,for analysing Z-scan curves of cascading nonlinear medium layers or a complicated cascading structure. A good agreement with the experimental data is obtained. The method would be useful to design optical limiters and to determine the nonlinearities of cascading medium layers.

  5. Gamma Splines and Wavelets

    Directory of Open Access Journals (Sweden)

    Hannu Olkkonen

    2013-01-01

    Full Text Available In this work we introduce a new family of splines termed as gamma splines for continuous signal approximation and multiresolution analysis. The gamma splines are born by -times convolution of the exponential by itself. We study the properties of the discrete gamma splines in signal interpolation and approximation. We prove that the gamma splines obey the two-scale equation based on the polyphase decomposition. to introduce the shift invariant gamma spline wavelet transform for tree structured subscale analysis of asymmetric signal waveforms and for systems with asymmetric impulse response. Especially we consider the applications in biomedical signal analysis (EEG, ECG, and EMG. Finally, we discuss the suitability of the gamma spline signal processing in embedded VLSI environment.

  6. Double pulses and cascades above 2 PeV in IceCube

    CERN Document Server

    Palladino, Andrea; Villante, Francesco L; Vissani, Francesco

    2015-01-01

    IceCube collaboration has seen an unexpected population of high energy neutrinos compatible with an astrophysical origin. We consider two categories of events that can help to diagnose cosmic neutrinos: double pulse, that may allow us to clearly discriminate the cosmic component of tau neutrinos; cascades with deposited energy above 2 PeV, including events produced by electron antineutrinos at the Glashow resonance, that can be used to investigate the neutrino production mechanisms. We show that one half of the double pulse signal is due to the neutrinos spectral region already probed by IceCube. By normalizing to HESE data, we find that 10 more years are required to obtain 90% probability to observe a double pulse. The cascades above 2 PeV provide us a sensitive probe of the high energy tail of the neutrino spectrum and are potentially observable, but even in this case, the dependence on type of the source is mild. In fact we find that pp or p{\\gamma} mechanisms give a difference in the number of cascades ab...

  7. Beta and Gamma Gradients

    DEFF Research Database (Denmark)

    Løvborg, Leif; Gaffney, C. F.; Clark, P. A.;

    1985-01-01

    Experimental and/or theoretical estimates are presented concerning, (i) attenuation within the sample of beta and gamma radiation from the soil, (ii) the gamma dose within the sample due to its own radioactivity, and (iii) the soil gamma dose in the proximity of boundaries between regions...... of differing radioactivity. It is confirmed that removal of the outer 2 mm of sample is adequate to remove influence from soil beta dose and estimates are made of the error introduced by non-removal. Other evaluations include variation of the soil gamma dose near the ground surface and it appears...

  8. How the $\\gamma \\gamma$ Resonance Stole Christmas

    CERN Document Server

    Craig, Nathaniel; Kilic, Can; Thomas, Scott

    2015-01-01

    The experimental and theoretical implications of heavy di-gauge boson resonances that couple to, or are comprised of, new charged and strongly interacting matter are investigated. Observation and measurement of ratios of the resonant di-gauge boson channels $WW$, $ZZ$, $\\gamma \\gamma$, $Z \\gamma$, and $gg$ in the form of di-jets, provide a rather direct -- and for some ratios a rather robust -- probe of the gauge representations of the new matter. For a spin-zero resonance with the quantum numbers of the vacuum, the ratios of resonant $WW$ and $ZZ$ to $\\gamma \\gamma$ channels, as well as the longitudinal versus transverse polarization fractions in the $WW$ and $ZZ$ channels, provide extraordinarily sensitive probes for possible mixing with the Higgs boson, while di-Higgs and di-top resonant channels, $hh$ and $tt$, provide somewhat less sensitivity. We present a survey of possible underlying models for di-gauge boson resonances by considering various limits for the mass of the new charged and strongly interac...

  9. High energy electromagnetic cascades in extragalactic space: physics and features

    CERN Document Server

    Berezinsky, V

    2016-01-01

    Using the analytic modeling of the electromagnetic cascades compared with more precise numerical simulations we describe the physical properties of electromagnetic cascades developing in the universe on CMB and EBL background radiations. A cascade is initiated by very high energy photon or electron and the remnant photons at large distance have two-component energy spectrum, $\\propto E^{-2}$ ($\\propto E^{-1.9}$ in numerical simulations) produced at cascade multiplication stage, and $\\propto E^{-3/2}$ from Inverse Compton electron cooling at low energies. The most noticeable property of the cascade spectrum in analytic modeling is 'strong universality', which includes the standard energy spectrum and the energy density of the cascade $\\omega_{\\rm cas}$ as its only numerical parameter. Using numerical simulations of the cascade spectrum and comparing it with recent Fermi LAT spectrum we obtained the upper limit on $\\omega_{\\rm cas}$ stronger than in previous works. The new feature of the analysis is "$E_{\\max}$...

  10. Study of acoustic resonance of cascades

    Science.gov (United States)

    Honjo, M.; Tominaga, T.

    Discrete sounds and vibrations from guide vanes due to acoustic resonance in the vane flow path, are experimentally investigated. Other causes of pure sounds in stationary vanes are considered, such as direct radiation from wake shedding vortices, bubble vortices or leading edges, and radial or axial modes of air columns. Two-dimensional cascade tests are performed under various conditions, and the data are compared with theoretical results of flat plate cascades. Three-dimensional ducted guide vane model tests are carried out to apply prototype guide vanes, and to confirm the resonance of the two-dimensional tests. Results show that frequency is more sensitive to chord length than pitch length, and the ratio of the fluctuation frequency to fluid sound velocity/pitch length is independent of the scale. Bubble vortices on concave surfaces or leading edges are not exciting sources; and under the limit of solidity, no exciting energy can generate acoustic resonance in correspondence to the mode.

  11. Cascade morphology transition in bcc metals

    Energy Technology Data Exchange (ETDEWEB)

    Setyawan, Wahyu; Selby, A.; Juslin, Niklas; Stoller, Roger E.; Wirth, Brian D.; Kurtz, Richard J.

    2015-06-10

    Energetic atom collisions in solids induce shockwaves with complex morphologies. In this paper, we establish the existence of a morphological transition in such cascades. The order parameter of the morphology is defined as the exponent, $b$, in the defect production curve as a function of cascade energy ($N_F$$ \\sim$$E_{MD}^b$). Response of different bcc metals can be compared in a consistent energy domain when the energy is normalized by the transition energy, $\\mu$, between the high- and the low-energy regime. Using Cr, Fe, Mo and W data, an empirical formula of $\\mu$ as a function of displacement threshold energy, $E_d$, is presented for bcc metals.

  12. Cascade morphology transition in bcc metals.

    Science.gov (United States)

    Setyawan, Wahyu; Selby, Aaron P; Juslin, Niklas; Stoller, Roger E; Wirth, Brian D; Kurtz, Richard J

    2015-06-10

    Energetic atom collisions in solids induce shockwaves with complex morphologies. In this paper, we establish the existence of a morphological transition in such cascades. The order parameter of the morphology is defined as the exponent, b, in the defect production curve as a function of cascade energy (N(F) ~ E(MD)(b)). Response of different bcc metals can be compared in a consistent energy domain when the energy is normalized by the transition energy, μ, between the high- and the low-energy regime. Using Cr, Fe, Mo and W data, an empirical formula of μ as a function of displacement threshold energy, E(d), is presented for bcc metals. PMID:25985256

  13. Cascade Apartments: Deep Energy Multifamily Retrofit

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, A. [Washington State Univ. Energy Program, Olympia, WA (United States); Mattheis, L. [Washington State Univ. Energy Program, Olympia, WA (United States); Kunkle, R. [Washington State Univ. Energy Program, Olympia, WA (United States); Howard, L. [Washington State Univ. Energy Program, Olympia, WA (United States); Lubliner, M. [Washington State Univ. Energy Program, Olympia, WA (United States)

    2014-02-01

    In December of 2009-10, King County Housing Authority (KCHA) implemented energy retrofit improvements in the Cascade multifamily community, located in Kent, Washington (marine climate.)This research effort involved significant coordination from stakeholders KCHA, WA State Department of Commerce, utility Puget Sound Energy, and Cascade tenants. This report focuses on the following three primary BA research questions: 1. What are the modeled energy savings using DOE low income weatherization approved TREAT software? 2. How did the modeled energy savings compare with measured energy savings from aggregate utility billing analysis? 3. What is the Savings to Investment Ratio (SIR) of the retrofit package after considering utility window incentives and KCHA capitol improvement funding.

  14. Cascade Apartments: Deep Energy Multifamily Retrofit

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, A.; Mattheis, L.; Kunkle, R.; Howard, L.; Lubliner, M.

    2014-02-01

    In December of 2009-10, King County Housing Authority (KCHA) implemented energy retrofit improvements in the Cascade multifamily community, located in Kent, Washington (marine climate.)This research effort involved significant coordination from stakeholders KCHA, WA State Department of Commerce, utility Puget Sound Energy, and Cascade tenants. This report focuses on the following three primary BA research questions : 1. What are the modeled energy savings using DOE low income weatherization approved TREAT software? 2. How did the modeled energy savings compare with measured energy savings from aggregate utility billing analysis? 3. What is the Savings to Investment Ratio (SIR) of the retrofit package after considering utility window incentives and KCHA capitol improvement funding.

  15. Regimes of turbulence without an energy cascade

    CERN Document Server

    Barenghi, C F; Baggaley, A W

    2016-01-01

    Experiments and numerical simulations of turbulent $^4$He and $^3$He-B have established that, at hydrodynamic length scales larger than the average distance between quantum vortices, the energy spectrum obeys the same 5/3 Kolmogorov law which is observed in the homogeneous isotropic turbulence of ordinary fluids. The importance of the 5/3 law is that it points to the existence of a Richardson energy cascade from large eddies to small eddies. However, there is also evidence of quantum turbulent regimes without Kolmogorov scaling. This raises the important questions of why, in such regimes, the Kolmogorov spectrum fails to form, what is the physical nature of turbulence without energy cascade, and whether hydrodynamical models can account for the unusual behaviour of turbulent superfluid helium. In this work we describe simple physical mechanisms which prevent the formation of Kolmogorov scaling in the thermal counterflow, and analyze the conditions necessary for emergence of quasiclassical regime in quantum tu...

  16. Long-period cascaded fiber taper filters.

    Science.gov (United States)

    Martinez-Rios, A; Salceda-Delgado, G; Guerrero-Viramontes, J A

    2014-02-10

    Fiber filters based on periodic cascaded tapered fiber sections are demonstrated. The filters consist of up to seven tapered sections separated periodically by more than 3 mm from center to center, with nominal tapered sections of 1  mm×1  mm×1  mm longitudinal dimensions. The transmission spectrum consists of discrete notches, resembling those observed in long-period fiber gratings, which differs from the observed spectrum in Mach-Zender interferometers based on cascaded tapers. Its sensitivity to external perturbations, such as refractive index or mechanical stress, made the device potentially very useful as a sensor or tunable filter. PMID:24663276

  17. Cascaded trans-z-source inverters

    DEFF Research Database (Denmark)

    Li, Ding; Loh, Poh Chiang; Zhu, Miao;

    2011-01-01

    the compatibility for distributed sources. Unlike existing techniques, voltage stresses within the proposed inverters are better distributed among the passive components. Theoretical analysis for explaining these operating features has already been discussed before simulation were performed and an experimental......Z-source inverter is a recently proposed single-stage inverter with added voltage-boost capability for complementing the usual voltage-buck operation of a traditional voltage-source inverter. As long as the transformer element added in to the z-source concept, a trans-z-source inverter with one...... transformer and one capacitor is reported recently. This paper has adapted the cascaded concept into the trans-z-source and trans-quasi-z-source inverters to extend each to the cascaded topologies before combination is made with allowing more sources embedded which reduces the capacitor voltage and enhanced...

  18. Impact of Community Structure on Cascades

    OpenAIRE

    Moharrami, Mehrdad; Subramanian, Vijay; Liu, Mingyan; Lelarge, Marc

    2016-01-01

    The threshold model is widely used to study the propagation of opinions and technologies in social networks. In this model individuals adopt the new behavior based on how many neighbors have already chosen it. We study cascades under the threshold model on sparse random graphs with community structure to see whether the existence of communities affects the number of individuals who finally adopt the new behavior. Specifically, we consider the permanent adoption model where nodes that have ado...

  19. HIV treatment cascade in tuberculosis patients

    OpenAIRE

    Lessells, Richard J; Swaminathan, Soumya; Godfrey-Faussett, Peter

    2016-01-01

    Purpose of review Globally, the number of deaths associated with tuberculosis (TB) and HIV coinfection remains unacceptably high. We review the evidence around the impact of strengthening the HIV treatment cascade in TB patients and explore recent findings about how best to deliver integrated TB/HIV services. Recent findings There is clear evidence that the timely provision of antiretroviral therapy (ART) reduces mortality in TB/HIV coinfected adults. Despite this, globally in 2013, only arou...

  20. An asymmetric pericyclic cascade approach to oxindoles

    OpenAIRE

    Richmond, Edward

    2014-01-01

    The research in this thesis describes an asymmetric pericyclic cascade approach to the synthesis of a range of enantioenriched oxindoles using enantiopure oxazolidine derived nitrones and disubstituted ketenes. Chapter 1 aims to place this work in the context of the literature, describing other commonly employed or state-of-the-art asymmetric approaches to oxindoles and related compounds. Examples of where these approaches have been used successfully in the total synthesis of related indol...

  1. Controllability of nonlinear degenerate parabolic cascade systems

    Directory of Open Access Journals (Sweden)

    Mamadou Birba

    2016-08-01

    Full Text Available This article studies of null controllability property of nonlinear coupled one dimensional degenerate parabolic equations. These equations form a cascade system, that is, the solution of the first equation acts as a control in the second equation and the control function acts only directly on the first equation. We prove positive null controllability results when the control and a coupling set have nonempty intersection.

  2. Evolution of Vertebrate Phototransduction: Cascade Activation.

    Science.gov (United States)

    Lamb, Trevor D; Patel, Hardip; Chuah, Aaron; Natoli, Riccardo C; Davies, Wayne I L; Hart, Nathan S; Collin, Shaun P; Hunt, David M

    2016-08-01

    We applied high-throughput sequencing to eye tissue from several species of basal vertebrates (a hagfish, two species of lamprey, and five species of gnathostome fish), and we analyzed the mRNA sequences for the proteins underlying activation of the phototransduction cascade. The molecular phylogenies that we constructed from these sequences are consistent with the 2R WGD model of two rounds of whole genome duplication. Our analysis suggests that agnathans retain an additional representative (that has been lost in gnathostomes) in each of the gene families we studied; the evidence is strong for the G-protein α subunit (GNAT) and the cGMP phosphodiesterase (PDE6), and indicative for the cyclic nucleotide-gated channels (CNGA and CNGB). Two of the species (the hagfish Eptatretus cirrhatus and the lamprey Mordacia mordax) possess only a single class of photoreceptor, simplifying deductions about the composition of cascade protein isoforms utilized in their photoreceptors. For the other lamprey, Geotria australis, analysis of the ratios of transcript levels in downstream and upstream migrant animals permits tentative conclusions to be drawn about the isoforms used in four of the five spectral classes of photoreceptor. Overall, our results suggest that agnathan rod-like photoreceptors utilize the same GNAT1 as gnathostomes, together with a homodimeric PDE6 that may be agnathan-specific, whereas agnathan cone-like photoreceptors utilize a GNAT that may be agnathan-specific, together with the same PDE6C as gnathostomes. These findings help elucidate the evolution of the vertebrate phototransduction cascade from an ancestral chordate phototransduction cascade that existed prior to the vertebrate radiation. PMID:27189541

  3. Optical encryption with cascaded fractional wavelet transforms

    Institute of Scientific and Technical Information of China (English)

    BAO Liang-hua; CHEN Lin-fei; ZHAO Dao-mu

    2006-01-01

    On the basis of fractional wavelet transform, we propose a new method called cascaded fractional wavelet transform to encrypt images. It has the virtues of fractional Fourier transform and wavelet transform. Fractional orders, standard focal lengths and scaling factors are its keys. Multistage fractional Fourier transforms can add the keys easily and strengthen information security. This method can also realize partial encryption just as wavelet transform and fractional wavelet transform. Optical realization of encryption and decryption is proposed. Computer simulations confirmed its possibility.

  4. Cascade laser applications: trends and challenges

    Science.gov (United States)

    d'Humières, B.; Margoto, Éric; Fazilleau, Yves

    2016-03-01

    When analyses need rapid measurements, cost effective monitoring and miniaturization, tunable semiconductor lasers can be very good sources. Indeed, applications like on-field environmental gas analysis or in-line industrial process control are becoming available thanks to the advantage of tunable semiconductor lasers. Advances in cascade lasers (CL) are revolutionizing Mid-IR spectroscopy with two alternatives: interband cascade lasers (ICL) in the 3-6μm spectrum and quantum cascade lasers (QCL), with more power from 3 to 300μm. The market is getting mature with strong players for driving applications like industry, environment, life science or transports. CL are not the only Mid-IR laser source. In fact, a strong competition is now taking place with other technologies like: OPO, VCSEL, Solid State lasers, Gas, SC Infrared or fiber lasers. In other words, CL have to conquer a share of the Mid-IR application market. Our study is a market analysis of CL technologies and their applications. It shows that improvements of components performance, along with the progress of infrared laser spectroscopy will drive the CL market growth. We compare CL technologies with other Mid-IR sources and estimate their share in each application market.

  5. Prediction of Cascading Failures in Spatial Networks.

    Science.gov (United States)

    Shunkun, Yang; Jiaquan, Zhang; Dan, Lu

    2016-01-01

    Cascading overload failures are widely found in large-scale parallel systems and remain a major threat to system reliability; therefore, they are of great concern to maintainers and managers of different systems. Accurate cascading failure prediction can provide useful information to help control networks. However, for a large, gradually growing network with increasing complexity, it is often impractical to explore the behavior of a single node from the perspective of failure propagation. Fortunately, overload failures that propagate through a network exhibit certain spatial-temporal correlations, which allows the study of a group of nodes that share common spatial and temporal characteristics. Therefore, in this study, we seek to predict the failure rates of nodes in a given group using machine-learning methods. We simulated overload failure propagations in a weighted lattice network that start with a center attack and predicted the failure percentages of different groups of nodes that are separated by a given distance. The experimental results of a feedforward neural network (FNN), a recurrent neural network (RNN) and support vector regression (SVR) all show that these different models can accurately predict the similar behavior of nodes in a given group during cascading overload propagation.

  6. Gamma-ray sources

    International Nuclear Information System (INIS)

    Results are presented from an analysis of the celestial gamma-ray fine-scale structure based on over half of the data which may ultimately be available from the COS-B satellite. A catalogue consisting of 25 gamma-ray sources measured at energies above 100 MeV is presented. (Auth.)

  7. Gamma-sterilization

    International Nuclear Information System (INIS)

    The author makes a survey of his experience in sterilization and sterility control of medical products. At present three different methods are used, steamsterilization, gassterilizing and gammasterilizing. The investments and costs for gamma radiation is presented and a comparison of the costs for gamma- and gassterilization including sterility control is made. (M.S.)

  8. Star-forming galaxies as the origin of IceCube neutrinos: Reconciliation with Fermi-LAT gamma rays

    CERN Document Server

    Chakraborty, Sovan

    2016-01-01

    Cosmic ray accelerators like supernova and hypernova remnants in star forming galaxies are one of the most plausible sources of the IceCube observed diffuse astrophysical neutrinos. The neutrino producing hadronic processes will also produce a diffuse gamma ray flux, constrained by the Fermi-LAT bounds. The fact that point sources like blazars also contribute to the diffuse gamma ray flux implies large gamma opacity of the neutrino sources. Indeed, for these high redshift star forming galaxies the gamma absorption during the intergalactic propagation can be significant. In addition, large gamma attenuation inside these extreme source galaxies can reduce the cascade component of the diffuse flux. Under the current astrophysical uncertainties affecting these absorptions processes, we find the associated diffuse gamma ray flux can remain compatible with the current Fermi-LAT bounds.

  9. Resolved photon and multi-component model for $\\gamma^*$p and $\\gamma^* \\gamma^*$ total cross section

    OpenAIRE

    Szczurek, A.; Pietrycki, T.

    2005-01-01

    We generalize our previous model for $\\gamma^* p$ scattering to $\\gamma \\gamma$ scattering. Performing a new simultaneous fit to $\\gamma^* p$ and $\\gamma \\gamma$ total cross section we find an optimal set of parameters to describe both processes. We propose new measures of factorization breaking for $\\gamma^* \\gamma^*$ collisions and present results for our new model.

  10. Colliding. gamma. e- and. gamma gamma. -beams on the basis of electron-positron linear colliders

    Energy Technology Data Exchange (ETDEWEB)

    Ginzburg, I.F.; Kotkin, G.L.; Serbo, V.G.; Tel' nov, V.I.

    1983-08-01

    Main properties of the ..gamma..e and ..gamma gamma.. collisions are discussed in some detail with application to the generation of colliding ..gamma..e and ..gamma gamma.. beams basing on the designed linear accelerators with colliding e/sup +/e/sup -/ beams, VLEEP and SLC, as it was proposed in a previous work. Intensive ..gamma.. beams with the energy 50 GeV would be produced from scattering of the laser light focused to the electron beams of the accelerators. Laser radiation is focused to the electron beam in the conversion region at a distance of about 10 cm from the place of collision. After scattering on electrons high-energy photons move practically along the electron primary trajectories and are focused in the collision region. The electrons are deflected from the collision region by means of approximately 1 T magnetic field. Then the produced ..gamma..-beam collides with an electron beam or a similar ..gamma..-beam. In the case when the maximum luminosity (L) is attained, the luminosity distribution in the invariant mass of the ..gamma..e or ..gamma gamma.. systems is wide. A monochromatization of the collisions up to the level of 5-10% is possible. That will entail a decrease in the luminosity, the procedure is most effective if one uses the electrons and the laser photons with opposite helicities. Examples of physically interesting problems to be investigated with the proposed ..gamma..e and ..gamma gamma.. beams are suggested.

  11. Gamma-ray spectroscopy of neutron-rich products of heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, M.P.; Janssens, R.V.F.; Ahmad, I. [and others

    1995-08-01

    Thick-target {gamma}{gamma} coincidence techniques are being used to explore the spectroscopy of otherwise hard-to-reach neutron-rich products of deep-inelastic heavy ion reactions. Extensive {gamma}{gamma} coincidence measurements were performed at ATLAS using pulsed beams of {sup 80}Se, {sup 136}Xe, and {sup 238}U on lead-backed {sup 122,124}Sn targets with energies 10-15% above the Coulomb barrier. Gamma-ray coincidence intensities were used to map out yield distributions with A and Z for even-even product nuclei around the target and around the projectile. The main features of the yield patterns are understandable in terms of N/Z equilibration. We had the most success in studying the decays of yrast isomers. Thus far, more than thirty new {mu}s isomers in the Z = 50 region were found and characterized. Making isotopic assignments for previously unknown {gamma}-ray cascades proves to be one of the biggest problems. Our assignments were based (a) on rare overlaps with radioactivity data, (b) on the relative yields with different beams, and (c) on observed cross-coincidences between {gamma} rays from light and heavy reaction partners. However, the primary products of deep inelastic collisions often are sufficiently excited for subsequent neutron evaporation, so {gamma}{gamma} cross-coincidence results require careful interpretation.

  12. Exclusive Photoproduction of the Cascade (Xi) Hyperons

    CERN Document Server

    Price, J W; Berman, B L; Laget, J M; Strauch, S; Adams, G; Afanasiev, A V; Ambrozewicz, P; Anghinolfi, M; Annand, J R M; Armstrong, C; Asavapibhop, B; Avakian, H; Bagdasaryan, H; Ball, J P; Barrow, S; Battaglieri, M; Beard, K; Bektasoglu, M; Bellis, M; Benmouna, N; Bianchi, N; Biselli, A S; Boiarinov, S; Bonner, B E; Bouchigny, S; Bradford, R; Branford, D; Briscoe, W J; Brooks, W K; Burkert, V D; Butuceanu, C; Calarco, J R; Carman, D S; Carnahan, B; Chen, S; Cole, P L; Coleman, A; Cords, D; Corvisiero, P; Crabb, D; Crannell, H; Cummings, J P; De Sanctis, E; De Vita, R; Degtyarenko, P V; Denizli, H; Dennis, L; Dharmawardane, K V; Dhuga, K S; Djalali, C; Dodge, G E; Doughty, D; Dragovitsch, P; Dugger, M; Dytman, S; Dzyubak, O P; Egiyan, H; Egiyan, K S; Elouadrhiri, L; Empl, A; Ent, R; Eugenio, P; Fatemi, R; Fedotov, G; Feldman, G; Feuerbach, R J; Ficenec, J; Forest, T A; Funsten, H; Gavalian, G; Gilfoyle, G P; Giovanetti, K L; Golovatch, E; Gordon, C I O; Gothe, R W; Griffioen, K; Guidal, M; Guillo, M R; Guler, N; Guo, L; Gyurjyan, V; Hadjidakis, C; Hakobyan, R S; Hardie, J; Heddle, D; Heimberg, P; Hersman, F W; Hicks, K; Hleiqawi, K; Holtrop, M; Hu, J; Huertas, M; Hyde-Wright, C E; Ilieva, Y Y; Ireland, D; Ito, M M; Jenkins, D; Jo, H S; Joo, K; Jüngst, H G; Kellie, J; Khandaker, M; Kim, K Y; Kim, K; Kim, W; Klein, A; Klein, F J; Klimenko, A V; Klusman, M; Kossov, M; Kramer, L H; Kuang, Y; Kuhn, S E; Kühn, J; Lachniet, J; Langheinrich, J; Lawrence, D; Ji Li; Lima, A C S; Livingston, K; Lukashin, K; Manak, J J; Marchand, C; McAleer, S; McNabb, J W C; Mecking, B A; Melone, J J; Mestayer, M D; Meyer, C A; Mikhailov, K; Minehart, R C; Mirazita, M; Miskimen, R; Morand, L; Morrow, S A; Muccifora, V; Müller, J; Murphy, L Y; Mutchler, G S; Napolitano, J; Nasseripour, R; Niccolai, S; Niculescu, G; Niculescu, I; Niczyporuk, B B; Niyazov, R A; Nozar, M; O'Brien, J T; O'Rielly, G V; Osipenko, M; Ostrovidov, A I; Park, K; Pasyuk, E A; Philips, S A; Pivnyuk, N; Pocanic, D; Pogorelko, O I; Polli, E; Popa, I; Pozdniakov, S; Preedom, B M; Prok, Y; Protopopescu, D; Qin, L M; Raue, B A; Riccardi, G; Ricco, G; Ripani, M; Ritchie, B G; Ronchetti, F; Rosner, G; Rossi, P; Rowntree, D; Rubin, P D; Sabatie, F; Salgado, C; Santoro, J P; Sapunenko, V; Schumacher, R A; Serov, V S; Shafi, A; Sharabyan, Yu G; Shaw, J; Skabelin, A V; Smith, E S; Smith, L C; Sober, D I; Stavinsky, A V; Stepanyan, S; Stoler, P; Strakovsky, I I; Suleiman, R; Taiuti, M; Taylor, S; Tedeschi, D J; Thoma, U; Thompson, R; Tkabladze, R; Todor, L; Tur, C; Ungaro, M; Vineyard, M F; Vlassov, A V; Wang, K; Weinstein, L B; Weygand, D P; Whisnant, C S; Williams, M; Wolin, E; Wood, M H; Yegneswaran, A; Yun, J; Zana, L

    2004-01-01

    We report on the first measurement of exclusive Xi-(1321) hyperon photoproduction in gamma p --> K+ K+ Xi- for 3.2 < E(gamma) < 3.9 GeV. The final state is identified by the missing mass in p(gamma,K+ K+)X measured with the CLAS detector at Jefferson Laboratory. We have detected a significant number of the ground-state Xi-(1321)1/2+, and have estimated the total cross section for its production. We have also observed the first excited state Xi-(1530)3/2+. Photoproduction provides a copious source of Xi's. We discuss the possibilities of a search for the recently proposed Xi5-- and Xi5+ pentaquarks.

  13. Production of Medical Radioisotopes with High Specific Activity in Photonuclear Reactions with $\\gamma$ Beams of High Intensity and Large Brilliance

    CERN Document Server

    Habs, D

    2010-01-01

    We study the production of radioisotopes for nuclear medicine in $(\\gamma,x{\\rm n}+y{\\rm p})$ photonuclear reactions or ($\\gamma,\\gamma'$) photoexcitation reactions with high flux [($10^{13}-10^{15}$)$\\gamma$/s], small diameter $\\sim (100 \\, \\mu$m$)^2$ and small band width ($\\Delta E/E \\approx 10^{-3}-10^{-4}$) $\\gamma$ beams produced by Compton back-scattering of laser light from relativistic brilliant electron beams. We compare them to (ion,$x$n$ + y$p) reactions with (ion=p,d,$\\alpha$) from particle accelerators like cyclotrons and (n,$\\gamma$) or (n,f) reactions from nuclear reactors. For photonuclear reactions with a narrow $\\gamma$ beam the energy deposition in the target can be managed by using a stack of thin target foils or wires, hence avoiding direct stopping of the Compton and pair electrons (positrons). $(\\gamma,\\gamma')$ isomer production via specially selected $\\gamma$ cascades allows to produce high specific activity in multiple excitations, where no back-pumping of the isomer to the ground st...

  14. GammaWorkshops Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Ramebaeck, H. (ed.) (Swedish Defence Research Agency (Sweden)); Straalberg, E. (Institute for Energy Technology, Kjeller (Norway)); Klemola, S. (Radiation and Nuclear Safety Authority, STUK (Finland)); Nielsen, Sven P. (Technical Univ. of Denmark. Risoe National Lab. for Sustainable Energy, Roskilde (Denmark)); Palsson, S.E. (Icelandic Radiation Safety Authority (Iceland))

    2012-01-15

    Due to a sparse interaction during the last years between practioners in gamma ray spectrometry in the Nordic countries, a NKS activity was started in 2009. This GammaSem was focused on seminars relevant to gamma spectrometry. A follow up seminar was held in 2010. As an outcome of these activities it was suggested that the 2011 meeting should be focused on practical issues, e.g. different corrections needed in gamma spectrometric measurements. This three day's meeting, GammaWorkshops, was held in September at Risoe-DTU. Experts on different topics relevant for gamma spectrometric measurements were invited to the GammaWorkshops. The topics included efficiency transfer, true coincidence summing corrections, self-attenuation corrections, measurement of natural radionuclides (natural decay series), combined measurement uncertainty calculations, and detection limits. These topics covered both lectures and practical sessions. The practical sessions included demonstrations of tools for e.g. corrections and calculations of the above meantioned topics. (Author)

  15. Ultra-bright GeV photon source via controlled electromagnetic cascades in laser-dipole waves

    CERN Document Server

    Gonoskov, A; Bastrakov, S; Efimenko, E; Ilderton, A; Kim, A; Marklund, M; Meyerov, I; Muraviev, A; Sergeev, A

    2016-01-01

    One aim of upcoming high-intensity laser facilities is to provide new high-flux gamma-ray sources. Electromagnetic cascades may serve for this, but are known to limit both field strengths and particle energies, restricting efficient production of photons to sub-GeV energies. Here we show how to create a directed GeV photon source, enabled by a controlled interplay between the cascade and anomalous radiative trapping. Using advanced 3D QED particle-in-cell (PIC) simulations and analytic estimates, we show that the concept is feasible for planned peak powers of 10 PW level. A higher peak power of 40 PW can provide $10^9$ photons with GeV energies in a well-collimated 3 fs beam, achieving peak brilliance ${9 \\times 10^{24}}$ ph s$^{-1}$mrad$^{-2}$mm$^{-2}$/0.1${\\%}$BW. Such a source would be a powerful tool for studying fundamental electromagnetic and nuclear processes.

  16. Gamma-ray Astronomy

    CERN Document Server

    Hinton, Jim

    2007-01-01

    The relevance of gamma-ray astronomy to the search for the origin of the galactic and, to a lesser extent, the ultra-high-energy cosmic rays has long been recognised. The current renaissance in the TeV gamma-ray field has resulted in a wealth of new data on galactic and extragalactic particle accelerators, and almost all the new results in this field were presented at the recent International Cosmic Ray Conference (ICRC). Here I summarise the 175 papers submitted on the topic of gamma-ray astronomy to the 30th ICRC in Merida, Mexico in July 2007.

  17. The gamma function

    CERN Document Server

    Artin, Emil

    2015-01-01

    This brief monograph on the gamma function was designed by the author to fill what he perceived as a gap in the literature of mathematics, which often treated the gamma function in a manner he described as both sketchy and overly complicated. Author Emil Artin, one of the twentieth century's leading mathematicians, wrote in his Preface to this book, ""I feel that this monograph will help to show that the gamma function can be thought of as one of the elementary functions, and that all of its basic properties can be established using elementary methods of the calculus."" Generations of teachers

  18. Heat cascading regenerative sorption heat pump

    Science.gov (United States)

    Jones, Jack A. (Inventor)

    1995-01-01

    A simple heat cascading regenerative sorption heat pump process with rejected or waste heat from a higher temperature chemisorption circuit (HTCC) powering a lower temperature physisorption circuit (LTPC) which provides a 30% total improvement over simple regenerative physisorption compression heat pumps when ammonia is both the chemisorbate and physisorbate, and a total improvement of 50% or more for LTPC having two pressure stages. The HTCC contains ammonia and a chemisorbent therefor contained in a plurality of canisters, a condenser-evaporator-radiator system, and a heater, operatively connected together. The LTPC contains ammonia and a physisorbent therefor contained in a plurality of compressors, a condenser-evaporator-radiator system, operatively connected together. A closed heat transfer circuit (CHTC) is provided which contains a flowing heat transfer liquid (FHTL) in thermal communication with each canister and each compressor for cascading heat from the HTCC to the LTPC. Heat is regenerated within the LTPC by transferring heat from one compressor to another. In one embodiment the regeneration is performed by another CHTC containing another FHTL in thermal communication with each compressor. In another embodiment the HTCC powers a lower temperature ammonia water absorption circuit (LTAWAC) which contains a generator-absorber system containing the absorbent, and a condenser-evaporator-radiator system, operatively connected together. The absorbent is water or an absorbent aqueous solution. A CHTC is provided which contains a FHTL in thermal communication with the generator for cascading heat from the HTCC to the LTAWAC. Heat is regenerated within the LTAWAC by transferring heat from the generator to the absorber. The chemical composition of the chemisorbent is different than the chemical composition of the physisorbent, and the absorbent. The chemical composition of the FHTL is different than the chemisorbent, the physisorbent, the absorbent, and ammonia.

  19. Cascade plant control by timer method

    International Nuclear Information System (INIS)

    The present invention relates to a method of controlling uranium flow rate through a cascaded centrifuge plant for the purpose of enriching uranium 235. Such a cascade includes multiple gas separation stage each of which consists of a plurality of centrifuges. The product gas usually includes a large amount of He gas, and a cold trap is used to eliminate the He from UF6. The cold trap is operated periodically in such a way that the mixed gas of He and UF6 is cooled to solidify only UF6 and then warmed to obtain UF6 by gasification. In order to operate the plant continuously, parallel multiple cold traps are operated alternatively. The operating conditions in such a complex cascade system are difficult to alter by conventional control methods. The present invention provides a rapid method of controlling the system when a certain percentage of the centrifuges in one stage malfunction. The control system consists of timers which are provided one for each cold trap to control the operational period of the trap. For example, if 20% of the centrifuges in a particular stage malfunction, the timer period of the cold traps attached to the normally operating centrifuge within the stage is maintained, and the period of all the other centrifuges are changed to 10/8 times that of the initial value. In this way the flow volume through all centrifuges except that in the particular stage is reduced to 80% of the initial value and the operation of the system can be continued with reduced efficiency. (Masui, R.)

  20. Dynamics of quantum cascade lasers: numerics

    Science.gov (United States)

    Van der Sande, Guy; Verschaffelt, Guy

    2016-04-01

    Since the original demonstration of terahertz quantum-cascade lasers (QCLs), the performance of these devices has shown rapid improvement. QCLs can now deliver milliwatts or more of continuous-wave radiation throughout the terahertz frequency range (300 GHz to 10 THz). Therefore, QCLs have become widely used in various applications such as spectroscopy, metrology or free-space telecommunications. For many of these applications there is a need for compact tuneable quantum cascade lasers. Nowadays most tuneable QCLs are based on a bulky external cavity configuration. We explore the possibility of tuning the operating wavelength through a fully integrated on-chip wavelength selective feedback applied to a dual wavelength QCL. Our numerical and analytical analyses are based on rate equation models describing the dynamics of QCLs extended to include delayed filtered optical feedback. We demonstrate the possibility to tune the operating wavelength by altering the absorption and/or amplification of the signal in the delayed feedback path. The tuning range of a laser is limited by the spectral width of its gain. For inter-band semiconductor lasers this spectral width is typically several tens of nm. Hence, the laser cavity supports the existence of multiple modes and on chip wavelength selective feedback has been demonstrated to be a promising tuning mechanism. We have selected a specific QCL gain structure with four energy levels and with two lasing transitions in the same cascade. In this scheme, the two lasing modes use a common upper level. Hence, the two modes compete in part for the same carriers to account for their optical gain. We have added delayed wavelength specific filtered optical feedback to the rate equation model describing these transitions. We have calculated the steady states and their stability in the absence of delay for the feedback field and studied numerically the case with non-zero delay. We have proven that wavelength tuning of a dual wavelength

  1. The current disequilibrium of North Cascade glaciers

    Science.gov (United States)

    Pelto, Mauri S.

    2006-03-01

    Three lines of evidence indicate that North Cascade (Washington, USA) glaciers are currently in a state of disequilibrium. First, annual balance measured on nine glaciers yields a mean cumulative balance for the 1984-2004 period of -8.58 m water equivalent (w.e.), a net loss of ice thickness exceeding 9.5 m. This is a significant loss for glaciers that average 30-50 m in thickness, representing 18-32% of their entire volume.Second, longitudinal profiles completed in 1984 and 2002 on 12 North Cascade glaciers confirm this volume change indicating a loss of -5.7 to -6.3 m in thickness (5.0-5.6 m w.e.) between 1984 and 2002, agreeing well with the measured cumulative balance of -5.52 m w.e. for the same period. The change in thickness on several glaciers has been equally substantial in the accumulation zone and the ablation zone, indicating that there is no point to which the glacier can retreat to achieve equilibrium. Substantial thinning along the entire length of a glacier is the key indicator that a glacier is in disequilibrium.Third, North Cascade glacier retreat is rapid and ubiquitous. All 47 glaciers monitored are currently undergoing significant retreat or, in the case of four, have disappeared. Two of the glaciers where mass balance observations were begun, Spider Glacier and Lewis Glacier, have disappeared. The retreat since 1984 of eight Mount Baker glaciers that were all advancing in 1975 has averaged 297 m. These observations indicate broad regional continuity in glacial response to climate.

  2. Stopping pions in high-energy nuclear cascades.

    Science.gov (United States)

    Jones, W. V.; Johnson, D. P.; Thompson, J. A.

    1973-01-01

    Results of Monte Carlo calculations for the number and energy spectra of charged pions from nuclear-electromagnetic cascades developing in rock are presented for primary hadron energies ranging from 3 to 3000 GeV. These spectra are given as functions of the longitudinal depth in the absorber and the lateral distance from the cascade axis. The number of charged pions which stop in the absorber increases with the primary energy of the hadron initiating the cascade.

  3. Beam combining of quantum cascade laser arrays.

    Science.gov (United States)

    Lee, Benjamin G; Kansky, Jan; Goyal, Anish K; Pflügl, Christian; Diehl, Laurent; Belkin, Mikhail A; Sanchez, Antonio; Capasso, Federico A

    2009-08-31

    Wavelength beam combining was used to co-propagate beams from 28 elements in an array of distributed-feedback quantum cascade lasers (DFB-QCLs). The beam-quality product of the array, defined as the product of near-field spot size and far-field divergence for the entire array, was improved by a factor of 21 by using wavelength beam combining. To demonstrate the applicability of wavelength beam combined DFB-QCL arrays for remote sensing, we obtained the absorption spectrum of isopropanol at a distance of 6 m from the laser array.

  4. Plant MAPK cascades: Just rapid signaling modules?

    KAUST Repository

    Boudsocq, Marie

    2015-08-27

    © 2015 Taylor & Francis Group, LLC. Abscisic acid (ABA) is a major phytohormone mediating important stress-related processes. We recently unveiled an ABA-activated MAPK signaling module constituted of MAP3K17/18-MKK3-MPK1/2/7/14. Unlike classical rapid MAPK activation, we showed that the activation of the new MAPK module is delayed and relies on the MAP3K protein synthesis. In this addendum, we discuss the role of this original and unexpected activation mechanism of MAPK cascades which suggests that MAPKs can regulate both early and longterm plant stress responses.

  5. The identification of a cascade hypernucleus

    CERN Document Server

    Mondal, A S; Husain, A; Kasim, M M

    1979-01-01

    In a systematic search for rare hypernuclear species in nuclear emulsion exposed to 3.0 GeV/c K/sup -/-mesons at the CERN PS, an event with three connecting stars has been observed. The two secondary stars are most probably due to the decay of a cascade hypernucleus according to the following channel: /sub Xi //sup -13/-C to /sub Lambda //sup 8 /Be+/sub Lambda //sup 5/He+Q. The binding energy of the Xi - hypernucleus is B/sub Xi /-(/sub Xi //sup 13/-C)=(18.1+or-3.2) MeV. (11 refs).

  6. Cascaded uncoupled dual-ring modulator

    CERN Document Server

    Gu, Tingyi; Wong, Chee Wei; Dong, Po

    2014-01-01

    We demonstrate that by coherent driving two uncoupled rings in same direction, the effective photon circulating time in the dual ring modulator is reduced, with increased modulation quality. The inter-ring detuning dependent photon dynamics, Q-factor, extinction ratio and optical modulation amplitude of two cascaded silicon ring resonators are studied and compared with that of a single ring modulator. Experimentally measured eye diagrams, together with coupled mode theory simulations, demonstrate the enhancement of dual ring configuration at 20 Gbps with a Q ~ 20,000.

  7. Long-Haul TCP vs. Cascaded TCP

    OpenAIRE

    Feng, Wu-chun

    2006-01-01

    In this work, we investigate the bandwidth and transfer time of long-haul TCP versus cascaded TCP [5]. First, we discuss the models for TCP throughput. For TCP flows in support of bulk data transfer (i.e., long-lived TCP flows), the TCP throughput models have been derived [2, 3]. These models rely on the congestion-avoidance algorithm of TCP. Though these models cannot be applied with short-lived TCP connections, our interest relative to logistical networking is in longer-li...

  8. Cascade model of power lines for PLC

    OpenAIRE

    Dziura, Michal

    2012-01-01

    This bachelor´s thesis deals with studies of power-line in terms of possibilities for using grid as a transmission medium for data transmission. Theoretical part is focused on PLC technology and the parameters of high-voltage lines. In very practical part the modeling of power-line by cascade parameters of two-port network is examined. Influence of va-rious changes in network topology are included in this thesis and also their influence on transfer function. The last part outlines the method ...

  9. Photonic crystal slab quantum cascade detector

    Energy Technology Data Exchange (ETDEWEB)

    Reininger, Peter, E-mail: peter.reininger@tuwien.ac.at; Schwarz, Benedikt; Harrer, Andreas; Zederbauer, Tobias; Detz, Hermann; Maxwell Andrews, Aaron; Gansch, Roman; Schrenk, Werner; Strasser, Gottfried [Institute for Solid State Electronics and Center for Micro- and Nanostructures, Vienna University of Technology, Floragasse 7, Vienna 1040 (Austria)

    2013-12-09

    In this Letter, we demonstrate the design, fabrication, and characterization of a photonic crystal slab quantum cascade detector (PCS-QCD). By employing a specifically designed resonant cavity, the performance of the photodetector is improved in three distinct ways. The PCS makes the QCD sensitive to surface normal incident light. It resonantly enhances the photon lifetime inside the active zone, thus increasing the photocurrent significantly. And, the construction form of the device inherently decreases the noise. Finally, we compare the characteristics of the PCS-QCD to a PCS - quantum well infrared photodetector and outline the advantages for certain fields of applications.

  10. Cascading Multicriticality in Nonrelativistic Spontaneous Symmetry Breaking

    CERN Document Server

    Griffin, Tom; Horava, Petr; Yan, Ziqi

    2015-01-01

    Without Lorentz invariance, spontaneous global symmetry breaking can lead to multicritical Nambu-Goldstone modes with a higher-order low-energy dispersion $\\omega\\sim k^n$ ($n=2,3,\\ldots$), whose naturalness is protected by polynomial shift symmetries. Here we investigate the role of infrared divergences and the nonrelativistic generalization of the Coleman-Hohenberg-Mermin-Wagner (CHMW) theorem. We find novel cascading phenomena with large hierarchies between the scales at which the value of $n$ changes, leading to an evasion of the "no-go" consequences of the relativistic CHMW theorem.

  11. Cascaded Mach–Zehnder interferometer tunable filters

    Science.gov (United States)

    Ovvyan, A. P.; Gruhler, N.; Ferrari, S.; Pernice, W. H. P.

    2016-06-01

    By cascading compact and low-loss Mach–Zehnder interferometers (MZIs) embedded within nanophotonic circuits we realize thermo-optically tunable optical filters for the visible wavelength range. Through phase tuning in either arm of the MZI, the filter response with maximum extinction can be shifted beyond one free-spectral range with low electrical power consumption. The working wavelength of our device is aligned with the emission wavelength of the silicon vacancy color center in diamond around 740 nm where we realize a filter depth beyond 36.5 dB. Our approach allows for efficient isolation of the emitted signal intensity in future hybrid nanodiamond-nanophotonic circuits.

  12. Heat flux dynamics in dissipative cascaded systems

    OpenAIRE

    de Lorenzo, S.; Farace, A.; Ciccarello, F.; De Palma, G; Giovannetti, V.

    2014-01-01

    We study the dynamics of heat flux in the thermalization process of a pair of identical quantum system that interact dissipatively with a reservoir in a {\\it cascaded} fashion. Despite the open dynamics of the bipartite system S is globally Lindbladian, one of the subsystems "sees" the reservoir in a state modified by the interaction with the other subsystem and hence it undergoes a non-Markovian dynamics. As a consequence, the heat flow exhibits a non-exponential time behaviour which can gre...

  13. Cascades of Fano resonances in Mie scattering

    Science.gov (United States)

    Rybin, M. V.; Sinev, I. S.; Samusev, K. B.; Limonov, M. F.

    2014-03-01

    The interference nature of resonant Mie scattering, which is described within the Fano model, has been demonstrated. The interference is caused by interaction of an incident electromagnetic wave with reemitted waves that correspond to eigenmodes of a scattering particle. Mie scattering due to the interference can be represented in the form of cascades of resonance lines of different shapes, each of which is described by the classical Fano formula. The effect is observed in resonant light scattering by an arbitrary body of revolution and discussed in detail using the example of scattering by an infinite homogeneous dielectric cylinder.

  14. Multilevel Inverter by Cascading Industrial VSI

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Blaabjerg, Frede; Pedersen, John Kim;

    2002-01-01

    -source inverter that uses three IGBT triphase inverter modules along with an output transformer to obtain a 3 p.u. multilevel output voltage is introduced. The system yields in high-quality multistep voltage with up to 4 levels and low dv/dt, balanced operation of the inverter modules, each supplying a third...... of the motor rated kVA. The concept of using cascaded inverters is further extended to a new modular motor-modular inverter system where the motor winding connections are reconnected into several three-phase groups, either six-lead or 12-lead connection according to the voltage level, each powered...

  15. The Cascade of Non-Stationarity

    Science.gov (United States)

    Belmont, P.; Kumarasamy, K.; Kelly, S. A.; Schaffrath, K. R.; Beach, T. J.

    2014-12-01

    Landscapes and channel networks are dynamic systems, often characterized by immense variability in time and space. Systematic shifts in hydrologic, geomorphic, or ecologic drivers can cause a cascade of changes within the system, which may fundamentally alter the way the system itself functions. Due to variability in resilience and resisting forces throughout the landscape, this cascade of changes may manifest in different ways within any given system. Humans may also exert considerable influence, often amplifying or damping system response. We illustrate the cascading effects of non-stationary hydrology and geomorphology in the Minnesota River Basin (MRB), a 44,000 km2 natural laboratory in which pervasive landscape disturbance has been triggered by several well-documented events. Rapid base-level lowering 13,400 YBP along the mainstem Minnesota River created a wave of incision, which continues to propagate up tributary channel networks. Temperature and precipitation have changed significantly in the MRB over the past century with rising temperatures, shifting precipitation patterns and an increase in heavy rainfall events. Streamflow has changed drastically and variably throughout the basin with 5% exceedance flows increasing 60-100% in recent decades, as increases in precipitation have been amplified by land management and artificial drainage. Increases in channel width and depth have occurred variably in the mainstem Minnesota River, the actively incising lower (knick zone) reaches of tributaries, and the low gradient, passively meandering reaches above the knick zones. Altered hydrologic regimes and channel morphologies, combined with increased sedimentation and nutrient loading have adversely affected aquatic biota via disruption of life cycles and habitat degradation. Existing landscape, water quality, and flood risk models are poorly equipped to deal with the cascading effects of non-stationarity and therefore may grossly over- or under

  16. Noise propagation in two-step series MAPK cascade.

    Directory of Open Access Journals (Sweden)

    Venkata Dhananjaneyulu

    Full Text Available Series MAPK enzymatic cascades, ubiquitously found in signaling networks, act as signal amplifiers and play a key role in processing information during signal transduction in cells. In activated cascades, cell-to-cell variability or noise is bound to occur and thereby strongly affects the cellular response. Commonly used linearization method (LM applied to Langevin type stochastic model of the MAPK cascade fails to accurately predict intrinsic noise propagation in the cascade. We prove this by using extensive stochastic simulations for various ranges of biochemical parameters. This failure is due to the fact that the LM ignores the nonlinear effects on the noise. However, LM provides a good estimate of the extrinsic noise propagation. We show that the correct estimate of intrinsic noise propagation in signaling networks that contain at least one enzymatic step can be obtained only through stochastic simulations. Noise propagation in the cascade depends on the underlying biochemical parameters which are often unavailable. Based on a combination of global sensitivity analysis (GSA and stochastic simulations, we developed a systematic methodology to characterize noise propagation in the cascade. GSA predicts that noise propagation in MAPK cascade is sensitive to the total number of upstream enzyme molecules and the total number of molecules of the two substrates involved in the cascade. We argue that the general systematic approach proposed and demonstrated on MAPK cascade must accompany noise propagation studies in biological networks.

  17. Dynamic gamma knife radiosurgery

    Science.gov (United States)

    Luan, Shuang; Swanson, Nathan; Chen, Zhe; Ma, Lijun

    2009-03-01

    Gamma knife has been the treatment of choice for various brain tumors and functional disorders. Current gamma knife radiosurgery is planned in a 'ball-packing' approach and delivered in a 'step-and-shoot' manner, i.e. it aims to 'pack' the different sized spherical high-dose volumes (called 'shots') into a tumor volume. We have developed a dynamic scheme for gamma knife radiosurgery based on the concept of 'dose-painting' to take advantage of the new robotic patient positioning system on the latest Gamma Knife C™ and Perfexion™ units. In our scheme, the spherical high dose volume created by the gamma knife unit will be viewed as a 3D spherical 'paintbrush', and treatment planning reduces to finding the best route of this 'paintbrush' to 'paint' a 3D tumor volume. Under our dose-painting concept, gamma knife radiosurgery becomes dynamic, where the patient moves continuously under the robotic positioning system. We have implemented a fully automatic dynamic gamma knife radiosurgery treatment planning system, where the inverse planning problem is solved as a traveling salesman problem combined with constrained least-square optimizations. We have also carried out experimental studies of dynamic gamma knife radiosurgery and showed the following. (1) Dynamic gamma knife radiosurgery is ideally suited for fully automatic inverse planning, where high quality radiosurgery plans can be obtained in minutes of computation. (2) Dynamic radiosurgery plans are more conformal than step-and-shoot plans and can maintain a steep dose gradient (around 13% per mm) between the target tumor volume and the surrounding critical structures. (3) It is possible to prescribe multiple isodose lines with dynamic gamma knife radiosurgery, so that the treatment can cover the periphery of the target volume while escalating the dose for high tumor burden regions. (4) With dynamic gamma knife radiosurgery, one can obtain a family of plans representing a tradeoff between the delivery time and the

  18. Dynamic gamma knife radiosurgery

    Energy Technology Data Exchange (ETDEWEB)

    Luan Shuang; Swanson, Nathan; Chen Zhe [Department of Computer Science, University of New Mexico, Albuquerque, NM 87131 (United States); Ma Lijun [Department of Radiation Oncology, University of California San Francisco, San Francisco, CA 94143 (United States)], E-mail: sluan@cs.unm.edu, E-mail: nate@cs.unm.edu, E-mail: zchen@cs.unm.edu, E-mail: lijunma@radonc.ucsf.edu

    2009-03-21

    Gamma knife has been the treatment of choice for various brain tumors and functional disorders. Current gamma knife radiosurgery is planned in a 'ball-packing' approach and delivered in a 'step-and-shoot' manner, i.e. it aims to 'pack' the different sized spherical high-dose volumes (called 'shots') into a tumor volume. We have developed a dynamic scheme for gamma knife radiosurgery based on the concept of 'dose-painting' to take advantage of the new robotic patient positioning system on the latest Gamma Knife C(TM) and Perfexion(TM) units. In our scheme, the spherical high dose volume created by the gamma knife unit will be viewed as a 3D spherical 'paintbrush', and treatment planning reduces to finding the best route of this 'paintbrush' to 'paint' a 3D tumor volume. Under our dose-painting concept, gamma knife radiosurgery becomes dynamic, where the patient moves continuously under the robotic positioning system. We have implemented a fully automatic dynamic gamma knife radiosurgery treatment planning system, where the inverse planning problem is solved as a traveling salesman problem combined with constrained least-square optimizations. We have also carried out experimental studies of dynamic gamma knife radiosurgery and showed the following. (1) Dynamic gamma knife radiosurgery is ideally suited for fully automatic inverse planning, where high quality radiosurgery plans can be obtained in minutes of computation. (2) Dynamic radiosurgery plans are more conformal than step-and-shoot plans and can maintain a steep dose gradient (around 13% per mm) between the target tumor volume and the surrounding critical structures. (3) It is possible to prescribe multiple isodose lines with dynamic gamma knife radiosurgery, so that the treatment can cover the periphery of the target volume while escalating the dose for high tumor burden regions. (4) With dynamic gamma knife radiosurgery, one can

  19. High energy gamma-rays from massive binary systems

    CERN Document Server

    Bednarek, W

    2008-01-01

    During last years a few massive binary systems have been detected in the TeV gamma-rays. This gamma-ray emission is clearly modulated with the orbital periods of these binaries suggesting its origin inside the binary system. In this paper we summarize the anisotropic IC e-p pair cascade model as likely explanation of these observations. We consider scenarios in which particles are accelerated to relativistic energies, either due to the presence of an energetic pulsar inside the binary, or as a result of accretion process onto the compact object during which the jet is launched from the inner part of the accretion disk, or in collisions of stellar winds from the massive companions.

  20. Measurements of high-energy {gamma}-rays with LaBr{sub 3}:Ce detectors

    Energy Technology Data Exchange (ETDEWEB)

    Ciemala, M. [Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, 31-342 Krakow (Poland)], E-mail: Michal.Ciemala@ifj.edu.pl; Balabanski, D. [INRNE, Bulgarian Academy of Sciences, BG-1784 Sofia (Bulgaria); Csatlos, M. [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), P.O. Box 51, H-4001 Debrecen (Hungary); Daugas, J.M. [CEA, DAM, DIF, F-91297 Arpajon Cedex (France); Georgiev, G. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), IN2P3-CNRS and Universite Paris-Sud, Bat 104-108, F-91405 Orsay Cedex (France); Gulyas, J. [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), P.O. Box 51, H-4001 Debrecen (Hungary); Kmiecik, M. [Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, 31-342 Krakow (Poland); Krasznahorkay, A. [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), P.O. Box 51, H-4001 Debrecen (Hungary); Lalkovski, S. [Faculty of Physics, University of Sofia, BG-1164 (Bulgaria); Lefebvre-Schuhl, A. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), IN2P3-CNRS and Universite Paris-Sud, Bat 104-108, F-91405 Orsay Cedex (France); Lozeva, R. [Instituut voor Kernen Stralingsfysica (IKS), Katholieke Universiteit Leuven, B-3001 Leuven (Belgium); Maj, A. [Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, 31-342 Krakow (Poland); Vitez, A. [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), P.O. Box 51, H-4001 Debrecen (Hungary)

    2009-09-01

    The full-energy peak efficiency calibration and the energy resolution measurements of the 2in.x2in.LaBr{sub 3}{gamma}-ray detector are presented for {gamma}-ray energies in the 700 keV-17.6 MeV range. Measurements were done using a combination of proton-capture nuclear reactions on {sup 27}Al, {sup 23}Na, {sup 39}K, {sup 7}Li and {sup 11}B for high-energy {gamma}-rays, and radioactive sources such as {sup 60}Co and {sup 152}Eu for the lowest energies. At high energies, two {gamma}-rays in a cascade from proton resonance capture were employed using Al, Na{sub 2}WO{sub 4}, K{sub 2}SO{sub 4} and LiBO{sub 2} targets. The obtained results were compared to the simulations performed using a GEANT4 code.

  1. Orphan {\\gamma}-ray flares from relativistic blobs encountering luminous stars

    CERN Document Server

    Banasiński, P; Sitarek, J

    2016-01-01

    We propose that {\\gamma} -rays in blazars can be produced during encounters of relativistic blobs of plasma with radiation field produced by luminous stars within (or close to) the jet. The blob is expected to contain relativistic electrons which comptonize stellar radiation to the GeV-TeV energies. Produced {\\gamma} -rays can initiate the Inverse Compton e+/- pair cascade in the stellar radiation. We propose that such a scenario can be responsible for the appearance of the so-called orphan {\\gamma} -ray flares. We show that the relativistic blob/luminous star collision model can explain the appearance of the extreme orphan {\\gamma} -ray flare observed in the GeV and sub-TeV energy range from the flat spectrum radio quasar PKS 1222+21.

  2. PLC-gamma1 and Rac1 coregulate EGF-induced cytoskeleton remodeling and cell migration.

    Science.gov (United States)

    Li, Siwei; Wang, Qian; Wang, Yi; Chen, Xinmei; Wang, Zhixiang

    2009-06-01

    It is well established that epidermal growth factor (EGF) induces the cytoskeleton reorganization and cell migration through two major signaling cascades: phospholipase C-gamma1 (PLC-gamma1) and Rho GTPases. However, little is known about the cross talk between PLC-gamma1 and Rho GTPases. Here we showed that PLC-gamma1 forms a complex with Rac1 in response to EGF. This interaction is direct and mediated by PLC-gamma1 Src homology 3 (SH3) domain and Rac1 (106)PNTP(109) motif. This interaction is critical for EGF-induced Rac1 activation in vivo, and PLC-gamma1 SH3 domain is actually a potent and specific Rac1 guanine nucleotide exchange factor in vitro. We have also demonstrated that the interaction between PLC-gamma1 SH3 domain and Rac1 play a significant role in EGF-induced F-actin formation and cell migration. We conclude that PLC-gamma1 and Rac1 coregulate EGF-induced cell cytoskeleton remodeling and cell migration by a direct functional interaction.

  3. The cascad spent fuel dry storage facility

    International Nuclear Information System (INIS)

    France has a wide variety of experimental spent fuels different from LWR spent fuel discharged from commercial reactors. Reprocessing such fuels would thus require the development and construction of special facilities. The French Atomic Energy Commission (CEA) has consequently opted for long-term interim storage of these spent fuels over a period of 50 years. Comparative studies of different storage concepts have been conducted on the basis of safety (mainly containment barriers and cooling), economic, modular design and operating flexibility criteria. These studies have shown that dry storage in a concrete vault cooled by natural convection is the best solution. A research and development program including theoretical investigations and mock-up tests confirmed the feasibility of cooling by natural convection and the validity of design rules applied for fuel storage. A facility called CASCAD was built at the CEA's Cadarache Nuclear Research Center, where it has been operational since mid-1990. This paper describes the CASCAD facility and indicates how its concept can be applied to storage of LWR fuel assemblies

  4. Power Grid Defense Against Malicious Cascading Failure

    CERN Document Server

    Shakarian, Paulo; Lindelauf, Roy

    2014-01-01

    An adversary looking to disrupt a power grid may look to target certain substations and sources of power generation to initiate a cascading failure that maximizes the number of customers without electricity. This is particularly an important concern when the enemy has the capability to launch cyber-attacks as practical concerns (i.e. avoiding disruption of service, presence of legacy systems, etc.) may hinder security. Hence, a defender can harden the security posture at certain power stations but may lack the time and resources to do this for the entire power grid. We model a power grid as a graph and introduce the cascading failure game in which both the defender and attacker choose a subset of power stations such as to minimize (maximize) the number of consumers having access to producers of power. We formalize problems for identifying both mixed and deterministic strategies for both players, prove complexity results under a variety of different scenarios, identify tractable cases, and develop algorithms f...

  5. Flow characteristics of the Cascade granular blanket

    International Nuclear Information System (INIS)

    Analysis of a single granule on a rotating cone shows that for the 350 half-angle, double-cone-shaped Cascade chamber, blanket granules will stay against the chamber wall if the rotational speed is 50 rpm or greater. The granules move axially down the wall with a slight (5-mm or less) sinusoidal oscillation in the circumferential direction. Granule chute-flow experiments confirm that two-layered flow can be obtained when the chute is inclined slightly above the granular material angle of repose. The top surface layer is thin and fast moving (supercritical flow). A thick bottom layer moves more slowly (subcritical flow controlled at the exit) with a velocity that increases with distance from the bottom of the chute. This is a desirable velocity profile because in the Cascade chamber about one-third of the fusion energy is deposited in the form of x rays and fusion-fuel-pellet debris in the top surface (inner-radius) layer

  6. Quantitative analysis of cascade impactor samples - revisited

    Science.gov (United States)

    Orlić , I.; Chiam, S. Y.; Sanchez, J. L.; Tang, S. M.

    1999-04-01

    Concentrations of aerosols collected in Singapore during the three months long haze period that affected the whole South-East Asian region in 1997 are reported. Aerosol samples were continuously collected by using a fine aerosol sampler (PM2.5) and occasionally with a single orifice cascade impactor (CI) sampler. Our results show that in the fine fraction (<2.5 μm) the concentrations of two well-known biomass burning products, i.e. K and S were generally increased by a factor 2-3 compared to the non-hazy periods. However, a discrepancy was noticed, at least for elements with lower atomic number (Ti and below) between the results obtained by the fine aerosol sampler and the cascade impactor. Careful analysis by means of Nuclear Microscopy, in particular by the Scanning Transmission Ion Microscopy (STIM) technique, revealed that thicknesses of the lower CI stages exceeded thick target limits for 2 MeV protons. Detailed depth profiles of all CI stages were therefore measured using the STIM technique and concentrations corrected for absorption and proton energy loss. After correcting results for the actual sample thickness, concentrations of all major elements (S, Cl, K, Ca) agreed much better with the PM2.5 results. The importance of implementing thick target corrections in analysis of CI samples, especially those collected in the urban environments, is emphasized. Broad beam PIXE analysis approach is certainly not adequate in these cases.

  7. Cascade Distiller System Performance Testing Interim Results

    Science.gov (United States)

    Callahan, Michael R.; Pensinger, Stuart; Sargusingh, Miriam J.

    2014-01-01

    The Cascade Distillation System (CDS) is a rotary distillation system with potential for greater reliability and lower energy costs than existing distillation systems. Based upon the results of the 2009 distillation comparison test (DCT) and recommendations of the expert panel, the Advanced Exploration Systems (AES) Water Recovery Project (WRP) project advanced the technology by increasing reliability of the system through redesign of bearing assemblies and improved rotor dynamics. In addition, the project improved the CDS power efficiency by optimizing the thermoelectric heat pump (TeHP) and heat exchanger design. Testing at the NASA-JSC Advanced Exploration System Water Laboratory (AES Water Lab) using a prototype Cascade Distillation Subsystem (CDS) wastewater processor (Honeywell d International, Torrance, Calif.) with test support equipment and control system developed by Johnson Space Center was performed to evaluate performance of the system with the upgrades as compared to previous system performance. The system was challenged with Solution 1 from the NASA Exploration Life Support (ELS) distillation comparison testing performed in 2009. Solution 1 consisted of a mixed stream containing human-generated urine and humidity condensate. A secondary objective of this testing is to evaluate the performance of the CDS as compared to the state of the art Distillation Assembly (DA) used in the ISS Urine Processor Assembly (UPA). This was done by challenging the system with ISS analog waste streams. This paper details the results of the AES WRP CDS performance testing.

  8. Detecting extended gamma-ray emission with the next generation Cherenkov telescopes

    CERN Document Server

    Alonso, M Fernandez; Rovero, A C

    2015-01-01

    Very high energy (VHE $>$100 GeV) gamma rays coming from blazars can produce pairs when interacting with the Extragalactic Background Light (EBL) and the Cosmic Microwave Background, generating an electromagnetic cascade. Depending on the Intergalactic Magnetic Field (IGMF) intensity, this cascade may result in an extended isotropic emission of photons around the source (halo), or in a broadening of the emission beam. The detection of these effects might lead to important constrains both on the IGMF intensity and the EBL density, quantities of great relevance in cosmological models. Using a Monte Carlo program, we simulate electromagnetic cascades for different values of the IGMF intensities and coming from a source similar to 1ES0229+200, a blazar with hard intrinsic spectrum at redshift $z=0.14$, which is an ideal distance for potentially observing the effect. We study the possible response of a generic future Cherenkov telescope using a simplified model for the sensitivity, effective area and angular resol...

  9. Quaternary Magmatism in the Cascades - Geologic Perspectives

    Science.gov (United States)

    Hildreth, Wes

    2007-01-01

    Foreward The Cascade magmatic arc is a belt of Quaternary volcanoes that extends 1,250 km from Lassen Peak in northern California to Meager Mountain in Canada, above the subduction zone where the Juan de Fuca Plate plunges beneath the North American Plate. This Professional Paper presents a synthesis of the entire volcanic arc, addressing all 2,300 known Quaternary volcanoes, not just the 30 or so visually prominent peaks that comprise the volcanic skyline. Study of Cascade volcanoes goes back to the geological explorers of the late 19th century and the seminal investigations of Howel Williams in the 1920s and 1930s. However, major progress and application of modern scientific methods and instrumentation began only in the 1970s with the advent of systematic geological, geophysical, and geochemical studies of the entire arc. Initial stimulus from the USGS Geothermal Research Program was enhanced by the USGS Volcano Hazards Program following the 1980 eruption of Mount St. Helens. Together, these two USGS Programs have provided more than three decades of stable funding, staffing, and analytical support. This Professional Paper summarizes the resultant USGS data sets and integrates them with the parallel contributions of other investigators. The product is based upon an all-encompassing and definitive geological database, including chemical and isotopic analyses to characterize the rocks and geochronology to provide the critical time constraints. Until now, this massive amount of data has not been summarized, and a systematic and uniform interpretation firmly grounded in geological fact has been lacking. Herein lies the primary utility of this Cascade volume. It not only will be the mandatory starting point for new workers, but also will provide essential geological context to broaden the perspectives of current investigators of specific Cascade volcanoes. Wes Hildreth's insightful understanding of volcanic processes and his uncompromising scientific integrity make him

  10. Characterizations of {\\Gamma}-AG^{**}-groupoids by their {\\Gamma}-ideals

    CERN Document Server

    Khan, Madad

    2010-01-01

    In this paper we have discusses {\\Gamma}-left, {\\Gamma}-right, {\\Gamma}-bi-, {\\Gamma}-quasi-, {\\Gamma}-interior and {\\Gamma}-ideals in {\\Gamma}-AG^{**}-groupoids and regular {\\Gamma}-AG^{**}-groupoids. Moreover we have proved that the set of {\\Gamma}-ideals in a regular {\\Gamma}-AG^{**}-groupoid form a semilattice structure. Also we have characterized a regular {\\Gamma}-AG^{**}-groupoid in terms of left ideals.

  11. Characterizations of gamma-AG^{**}-groupoids by the properties their gamma-ideals

    CERN Document Server

    Khan, Madad; Rehman, Inayatur

    2010-01-01

    In this paper we have discusses {\\Gamma}-left, {\\Gamma}-right, {\\Gamma}-bi-, {\\Gamma}-quasi-, {\\Gamma}-interior and {\\Gamma}-ideals in {\\Gamma}-AG^{**}-groupoids and regular {\\Gamma}-AG^{**}-groupoids. Moreover we have proved that the set of {\\Gamma}-ideals in a regular {\\Gamma}-AG^{**}-groupoid form a semilattice structure. Also we have characterized a regular {\\Gamma}-AG^{**}-groupoid in terms of left ideals.

  12. Measurement of anomalous couplings ZZ gamma , Z gamma gamma and ZZZ

    CERN Document Server

    Matteuzzi, C

    2001-01-01

    The anomalous couplings Z gamma gamma , ZZ gamma and ZZZ have been studied at LEP 2 with the reactions e/sup +/e/sup -/ to qq gamma , e /sup +/e/sup -/ to nu nu gamma and e/sup +/e/sup to / ZZ at square root s from 189 to 202 GeV. Limits are derived on three gauge neutral bosons couplings combining the results of the 3 experiments L3, OPAL and DELPHI.

  13. Study of gamma cascades of 59Ni by thermal neutron reaction

    OpenAIRE

    Son, Nguyen An

    2013-01-01

    The quantum properties are important to study nuclear structure. The energy, spin, parity, transition order are usually interesting to research. In this experiment, 59Ni is activated by thermal neutron on 3rd horizontal channel of Dalat nuclear Reactor.

  14. Anomalous correlation between hadron and electromagnetic particles in hadron and gamma-ray families

    Science.gov (United States)

    Tamada, M.

    1985-01-01

    Correlations between hadrons and electromagnetic particles were studied in the hadron-gamma families observed in the Chacaltaya emulsion chamber experiment. It is found that there exist a number of hadrons which associate electromagnetic showers in extraordinarily close vicinity. The probability to have such a large number of hadrons associating electromagnetic showers, expected from background calculation, is found to be negligibly small and it means there exists anomalous correlation between hadrons and electromagnetic particles in the characteristic spread of atmospheric electromagnetic cascade.

  15. A 2.5 kW cascaded Schwarz converter for 20 kHz power distribution

    Science.gov (United States)

    Shetler, Russell E.; Stuart, Thomas A.

    Because it avoids the high currents in a parallel loaded capacitor, the cascaded Schwarz converter should offer better component utilization than converters with sinusoidal output voltages. The circuit is relatively easy to protect, and it provides a predictable trapezoidal voltage waveform that should be satisfactory for 20-kHz distribution systems. Analysis of the system is enhanced by plotting curves of normalized variables vs. gamma(1), where gamma(1) is proportional to the variable frequency of the first stage. Light-load operation is greatly improved by the addition of a power recycling rectifier bridge that is back biased at medium to heavy loads. Operation has been verified on a 2.5-kW circuit that uses input and output voltages in the same range as those anticipated for certain future spacecraft power systems.

  16. A 2.5 kW cascaded Schwarz converter for 20 kHz power distribution

    Science.gov (United States)

    Shetler, Russell E.; Stuart, Thomas A.

    1989-01-01

    Because it avoids the high currents in a parallel loaded capacitor, the cascaded Schwarz converter should offer better component utilization than converters with sinusoidal output voltages. The circuit is relatively easy to protect, and it provides a predictable trapezoidal voltage waveform that should be satisfactory for 20-kHz distribution systems. Analysis of the system is enhanced by plotting curves of normalized variables vs. gamma(1), where gamma(1) is proportional to the variable frequency of the first stage. Light-load operation is greatly improved by the addition of a power recycling rectifier bridge that is back biased at medium to heavy loads. Operation has been verified on a 2.5-kW circuit that uses input and output voltages in the same range as those anticipated for certain future spacecraft power systems.

  17. Dark Spatial Solitary Wave Due to Cascaded x(2) Nonlinearity

    Institute of Scientific and Technical Information of China (English)

    GAO Guan-Qie; CHEN Xian-Feng; CHEN Yu-Ping; WANG Fei-Yu; XIA Yu-Xing

    2004-01-01

    The formation of the dark spatial solitary wave in cascaded second harmonic generation processes is numerically studied based on the nonlinear-coupled equations. It is shown that the solitary wave exists when the effective three-order nonlinearity induced by cascaded second-order nonlinearity is negative.

  18. Quantum cascade lasers with an integrated polarization mode converter.

    Science.gov (United States)

    Dhirhe, D; Slight, T J; Holmes, B M; Hutchings, D C; Ironside, C N

    2012-11-01

    We discuss the design, fabrication and characterization of waveguide polarization mode converters for quantum cascade lasers operating at 4.6 μm. We have fabricated a quantum cascade laser with integrated polarization mode converter that emits light of 69% Transverse Electrical (TE) polarization from one facet and 100% Transverse Magnetic (TM) polarization from the other facet. PMID:23187389

  19. Quantum cascade lasers with an integrated polarization mode converter

    OpenAIRE

    Dhirhe, D.; Slight, T.J.; Holmes, B.M.; Hutchings, D.C.; Ironside, C. N.

    2012-01-01

    We discuss the design, fabrication and characterization of waveguide polarization mode converters for quantum cascade lasers operating at 4.6 μm. We have fabricated a quantum cascade laser with integrated polarization mode converter that emits light of 69% Transverse Electrical (TE) polarization from one facet and 100% Transverse Magnetic (TM) polarization from the other facet.

  20. Impedance Coordinative Control for Cascaded Converter in Bidirectional Application

    DEFF Research Database (Denmark)

    Tian, Yanjun; Deng, Fujin; Chen, Zhe;

    2015-01-01

    difference between forward and reversed power flow. This paper addresses the analysis with the topology of cascaded dual-active-bridge converter (DAB) with inverter, and the proposed control method can also be implemented in unidirectional applications and other general cascaded converter system...

  1. Intermittent Flow Regimes in a Transonic Fan Airfoil Cascade

    Directory of Open Access Journals (Sweden)

    J. Lepicovsky

    2004-01-01

    velocity.To date, this flow behavior has only been observed in a linear transonic cascade. Further research is necessary to confirm this phenomenon occurs in actual transonic fans and is not the by-product of an endwall restricted linear cascade.

  2. Signaling cascades modulate the speed of signal propagation through space.

    Directory of Open Access Journals (Sweden)

    Christopher C Govern

    Full Text Available BACKGROUND: Cells are not mixed bags of signaling molecules. As a consequence, signals must travel from their origin to distal locations. Much is understood about the purely diffusive propagation of signals through space. Many signals, however, propagate via signaling cascades. Here, we show that, depending on their kinetics, cascades speed up or slow down the propagation of signals through space, relative to pure diffusion. METHODOLOGY/PRINCIPAL FINDINGS: We modeled simple cascades operating under different limits of Michaelis-Menten kinetics using deterministic reaction-diffusion equations. Cascades operating far from enzyme saturation speed up signal propagation; the second mobile species moves more quickly than the first through space, on average. The enhanced speed is due to more efficient serial activation of a downstream signaling module (by the signaling molecule immediately upstream in the cascade at points distal from the signaling origin, compared to locations closer to the source. Conversely, cascades operating under saturated kinetics, which exhibit zero-order ultrasensitivity, can slow down signals, ultimately localizing them to regions around the origin. CONCLUSIONS/SIGNIFICANCE: Signal speed modulation may be a fundamental function of cascades, affecting the ability of signals to penetrate within a cell, to cross-react with other signals, and to activate distant targets. In particular, enhanced speeds provide a way to increase signal penetration into a cell without needing to flood the cell with large numbers of active signaling molecules; conversely, diminished speeds in zero-order ultrasensitive cascades facilitate strong, but localized, signaling.

  3. 36 CFR 7.66 - North Cascades National Park.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false North Cascades National Park. 7.66 Section 7.66 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.66 North Cascades National Park....

  4. Anomalous dissipation and energy cascade in 3D inviscid flows

    CERN Document Server

    Dascaliuc, Radu

    2011-01-01

    Adopting the setting for the study of existence and scale locality of the energy cascade in 3D viscous flows in physical space introduced in [arXiv:1101.2193] to 3D inviscid flows, it is shown that the anomalous dissipation is indeed capable of triggering the cascade which then continues ad infinitum, confirming Onsager's predictions.

  5. A simple model of global cascades on random networks

    Science.gov (United States)

    Watts, Duncan J.

    2002-04-01

    The origin of large but rare cascades that are triggered by small initial shocks is a phenomenon that manifests itself as diversely as cultural fads, collective action, the diffusion of norms and innovations, and cascading failures in infrastructure and organizational networks. This paper presents a possible explanation of this phenomenon in terms of a sparse, random network of interacting agents whose decisions are determined by the actions of their neighbors according to a simple threshold rule. Two regimes are identified in which the network is susceptible to very large cascadesherein called global cascadesthat occur very rarely. When cascade propagation is limited by the connectivity of the network, a power law distribution of cascade sizes is observed, analogous to the cluster size distribution in standard percolation theory and avalanches in self-organized criticality. But when the network is highly connected, cascade propagation is limited instead by the local stability of the nodes themselves, and the size distribution of cascades is bimodal, implying a more extreme kind of instability that is correspondingly harder to anticipate. In the first regime, where the distribution of network neighbors is highly skewed, it is found that the most connected nodes are far more likely than average nodes to trigger cascades, but not in the second regime. Finally, it is shown that heterogeneity plays an ambiguous role in determining a system's stability: increasingly heterogeneous thresholds make the system more vulnerable to global cascades; but an increasingly heterogeneous degree distribution makes it less vulnerable.

  6. Influence of blood flow on the coagulation cascade

    DEFF Research Database (Denmark)

    The influence of diffusion and convetive flows on the blood coagulation cascade is investigated for a controlled perfusion experiment. We present a cartoon model and reaction schemes for parts of the coagulation cascade with sunsequent set up of a mathematical model in two space dimensions plus one...

  7. Deformed rotational cascades in {sup 152}Dy: Further evidence for shape coexistence at high spin

    Energy Technology Data Exchange (ETDEWEB)

    Smith, M. B. [Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, (United Kingdom); Department of Electronic Engineering and Physics, University of Paisley, Paisley PA1 2BE, (United Kingdom); Appelbe, D. E. [Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, (United Kingdom); Twin, P. J. [Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, (United Kingdom); Beausang, C. W. [Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, (United Kingdom); Wright Nuclear Structure Laboratory, Yale University, 272 Whitney Avenue, New Haven, Connecticut 06520 (United States); Beck, F. A. [Institut de Recherches Subatomiques, F-67037 Strasbourg Cedex 2, (France); Bentley, M. A. [School of Sciences, Staffordshire University, College Road, Stoke-on-Trent ST4 2DE, (United Kingdom); Cullen, D. M. [Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, (United Kingdom); Curien, D. [Institut de Recherches Subatomiques, F-67037 Strasbourg Cedex 2, (France); Dagnall, P. J. [Schuster Laboratory, University of Manchester, Manchester M13 9PL, (United Kingdom); De France, G. [Institut de Recherches Subatomiques, F-67037 Strasbourg Cedex 2, (France)] (and others)

    2000-03-01

    Two new rotational bands have been observed in the {sup 152}Dy nucleus following experiments performed using the EUROGAM {gamma}-ray spectrometer. Several transitions have been observed that link these new bands into the known single-particle states. Using the Doppler shift attenuation method, the quadrupole moment of the previously-known rotational sequence has been measured. The value of Q{sub band}=3.85{+-}0.06 e b confirms the deformed nature of this cascade. The structures of the three bands are discussed in terms of the occupation of both paired and unpaired orbitals, and are found to be in good agreement with theoretical calculations. The observation of two new bands further extends the concept of shape coexistence in the {sup 152}Dy nucleus. (c) 2000 The American Physical Society.

  8. Gamma ray camera

    Science.gov (United States)

    Perez-Mendez, Victor

    1997-01-01

    A gamma ray camera for detecting rays emanating from a radiation source such as an isotope. The gamma ray camera includes a sensor array formed of a visible light crystal for converting incident gamma rays to a plurality of corresponding visible light photons, and a photosensor array responsive to the visible light photons in order to form an electronic image of the radiation therefrom. The photosensor array is adapted to record an integrated amount of charge proportional to the incident gamma rays closest to it, and includes a transparent metallic layer, photodiode consisting of a p-i-n structure formed on one side of the transparent metallic layer, and comprising an upper p-type layer, an intermediate layer and a lower n-type layer. In the preferred mode, the scintillator crystal is composed essentially of a cesium iodide (CsI) crystal preferably doped with a predetermined amount impurity, and the p-type upper intermediate layers and said n-type layer are essentially composed of hydrogenated amorphous silicon (a-Si:H). The gamma ray camera further includes a collimator interposed between the radiation source and the sensor array, and a readout circuit formed on one side of the photosensor array.

  9. Degassing cascades in a shear-thinning viscoelastic fluid

    CERN Document Server

    Vidal, Valérie; Divoux, Thibaut; Géminard, Jean-Christophe

    2011-01-01

    We report the experimental study of the degassing dynamics through a thin layer of shear-thinning viscoelastic fluid (CTAB/NaSal solution), when a constant air flow is imposed at its bottom. Over a large range of parameters, the air is periodically released through series of successive bubbles, hereafter named {\\it cascades}. Each cascade is followed by a continuous degassing, lasting for several seconds, corresponding to an open channel crossing the fluid layer. The periodicity between two cascades does not depend on the injected flow-rate. Inside one cascade, the properties of the overpressure signal associated with the successive bubbles vary continuously. The pressure threshold above which the fluid starts flowing, fluid deformation and pressure drop due to degassing through the thin fluid layer can be simply described by a Maxwell model. We point out that monitoring the evolution inside the cascades provides a direct access to the characteristic relaxation time associated with the fluid rheology.

  10. On Watts' Cascade Model with Random Link Weights

    CERN Document Server

    Hurd, T R

    2012-01-01

    We study an extension of Duncan Watts' 2002 model of information cascades in social networks where edge weights are taken to be random, an innovation motivated by recent applications of cascade analysis to systemic risk in financial networks. The main result is a probabilistic analysis that characterizes the cascade in an infinite network as the fixed point of a vector-valued mapping, explicit in terms of convolution integrals that can be efficiently evaluated numerically using the fast Fourier transform algorithm. A second result gives an approximate probabilistic analysis of cascades on "real world networks", finite networks based on a fixed deterministic graph. Extensive cross testing with Monte Carlo estimates shows that this approximate analysis performs surprisingly well, and provides a flexible microscope that can be used to investigate properties of information cascades in real world networks over a wide range of model parameters.

  11. Tolerance of edge cascades with coupled map lattices methods

    Institute of Scientific and Technical Information of China (English)

    Cui Di; Gao Zi-You; Zheng Jian-Feng

    2009-01-01

    This paper studies the cascading failure on random networks and scale-free networks by introducing the tolerance parameter of edge based on the coupled map lattices methods. The whole work focuses on investigating some indices including the number of failed edges, dynamic edge tolerance capacity and the perturbation of edge. In general, it assumes that the perturbation is attributed to the normal distribution in adopted simulations. By investigating the effectiveness of edge tolerance in scale-free and random networks, it finds that the larger tolerance parameter 位 can more efficiently delay the cascading failure process for scale-free networks than random networks. These results indicate that the cascading failure process can be effectively controlled by increasing the tolerance parameter A. Moreover, the simulations also show that, larger variance of perturbation can easily trigger the cascading failures than the smaller one. This study may be useful for evaluating efficiency of whole traffic systems, and for alleviating cascading failure in such systems.

  12. Spatio-temporal propagation of cascading overload failures

    CERN Document Server

    Zhao, Jichang; Sanhedrai, Hillel; Cohen, Reuven; Havlin, Shlomo

    2015-01-01

    Different from the direct contact in epidemics spread, overload failures propagate through hidden functional dependencies. Many studies focused on the critical conditions and catastrophic consequences of cascading failures. However, to understand the network vulnerability and mitigate the cascading overload failures, the knowledge of how the failures propagate in time and space is essential but still missing. Here we study the spatio-temporal propagation behavior of cascading overload failures analytically and numerically. The cascading overload failures are found to spread radially from the center of the initial failure with an approximately constant velocity. The propagation velocity decreases with increasing tolerance, and can be well predicted by our theoretical framework with one single correction for all the tolerance values. This propagation velocity is found similar in various model networks and real network structures. Our findings may help to predict and mitigate the dynamics of cascading overload f...

  13. Cascading Node Failure with Continuous States in Random Geometric Networks

    CERN Document Server

    Kamran, Khashayar

    2016-01-01

    The increasing complexity and interdependency of today's networks highlight the importance of studying network robustness to failure and attacks. Many large-scale networks are prone to cascading effects where a limited number of initial failures (due to attacks, natural hazards or resource depletion) propagate through a dependent mechanism, ultimately leading to a global failure scenario where a substantial fraction of the network loses its functionality. These cascading failure scenarios often take place in networks which are embedded in space and constrained by geometry. Building on previous results on cascading failure in random geometric networks, we introduce and analyze a continuous cascading failure model where a node has an initial continuously-valued state, and fails if the aggregate state of its neighbors fall below a threshold. Within this model, we derive analytical conditions for the occurrence and non-occurrence of cascading node failure, respectively.

  14. A modeling framework for system restoration from cascading failures.

    Science.gov (United States)

    Liu, Chaoran; Li, Daqing; Zio, Enrico; Kang, Rui

    2014-01-01

    System restoration from cascading failures is an integral part of the overall defense against catastrophic breakdown in networked critical infrastructures. From the outbreak of cascading failures to the system complete breakdown, actions can be taken to prevent failure propagation through the entire network. While most analysis efforts have been carried out before or after cascading failures, restoration during cascading failures has been rarely studied. In this paper, we present a modeling framework to investigate the effects of in-process restoration, which depends strongly on the timing and strength of the restoration actions. Furthermore, in the model we also consider additional disturbances to the system due to restoration actions themselves. We demonstrate that the effect of restoration is also influenced by the combination of system loading level and restoration disturbance. Our modeling framework will help to provide insights on practical restoration from cascading failures and guide improvements of reliability and resilience of actual network systems.

  15. Cascaded generation of coherent Raman dissipative solitons.

    Science.gov (United States)

    Kharenko, Denis S; Bednyakova, Anastasia E; Podivilov, Evgeniy V; Fedoruk, Mikhail P; Apolonski, Alexander; Babin, Sergey A

    2016-01-01

    The cascaded generation of a conventional dissipative soliton (at 1020 nm) together with Raman dissipative solitons of the first (1065 nm) and second (1115 nm) orders inside a common fiber laser cavity is demonstrated experimentally and numerically. With sinusoidal (soft) spectral filtering, the generated solitons are mutually coherent at a high degree and compressible down to 300 fs. Numerical simulation shows that an even higher degree of coherence and shorter pulses could be achieved with step-like (hard) spectral filtering. The approach can be extended toward a high-order coherent Raman dissipative soliton source offering numerous applications such as frequency comb generation, pulse synthesis, biomedical imaging, and the generation of a coherent mid-infrared supercontinuum. PMID:26696187

  16. Availability Cascades and the Sharing Economy

    DEFF Research Database (Denmark)

    Netter, Sarah

    2016-01-01

    As scholars search for a new concept that will provide answers on how modern societies should make sense of and resolve the social and environmental problems linked to our modes of production and consumption, the sharing economy is attracting increased attention. To better understand this emergent...... focus on a sharing economy and associated business and consumption models, this conceptual chapter applies cascade theory to some of the most pronounced narratives , suggesting a win-win scenario, especially as they relate to the claim of sustainability. Given academics, practitioners, and civil society......’s shared history of (too) rapidly embracing new concepts that enable both business opportunities and a clear conscience, this chapter proposes that the implications of the sharing economy should be critically explored before it is actively promoted as the latest best fix....

  17. High brightness angled cavity quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Heydari, D.; Bai, Y.; Bandyopadhyay, N.; Slivken, S.; Razeghi, M., E-mail: razeghi@eecs.northwestern.edu [Center for Quantum Devices, Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, Illinois 60208 (United States)

    2015-03-02

    A quantum cascade laser (QCL) with an output power of 203 W is demonstrated in pulsed mode at 283 K with an angled cavity. The device has a ridge width of 300 μm, a cavity length of 5.8 mm, and a tilt angle of 12°. The back facet is high reflection coated, and the front facet is anti-reflection coated. The emitting wavelength is around 4.8 μm. In distinct contrast to a straight cavity broad area QCL, the lateral far field is single lobed with a divergence angle of only 3°. An ultrahigh brightness value of 156 MW cm{sup −2 }sr{sup −1} is obtained, which marks the brightest QCL to date.

  18. Including electronic effects in damage cascade simulations

    International Nuclear Information System (INIS)

    A method for including the effects of electronic losses and electron-phonon coupling in radiation damage simulations has been developed and implemented for 10 keV cascades in Fe. The MD simulations are coupled to a continuum model for the electronic energy and energy lost by the atoms, due to electronic friction and electron-phonon coupling, is gained by electronic system. Electronic energy transport is described by the heat diffusion equation and energy is returned to the lattice via a stochastic force. Thus the temperature of the atomic system is controlled by a Langevin thermostat at the local electronic temperature, which varies with time and space. The results of simulations with this inhomogeneous thermostat are compared with those of homogeneous (constant temperature) thermostat simulations for a range of electron-phonon coupling strengths. The residual defect concentration was found to have a non-monotonic variation with coupling strength.

  19. Free energy cascade in gyrokinetic turbulence

    CERN Document Server

    Navarro, A Bañón; Albrecht-Marc, M; Merz, F; Görler, T; Jenko, F; Carati, D

    2010-01-01

    In gyrokinetic theory, the quadratic nonlinearity is known to play an important role in the dynamics by redistributing (in a conservative fashion) the free energy between the various active scales. In the present study, the free energy transfer is analyzed for the case of ion temperature gradient driven turbulence. It is shown that it shares many properties with the energy transfer in fluid turbulence. In particular, one finds a forward (from large to small scales), extremely local, and self-similar cascade of free energy in the plane perpendicular to the background magnetic field. These findings shed light on some fundamental properties of plasma turbulence, and encourage the development of large eddy simulation techniques for gyrokinetics.

  20. Interface Phonon Modes in Quantum Cascade Lasers

    Institute of Scientific and Technical Information of China (English)

    YU Bing; CAO Jun-Cheng; FENG Song-Lin

    2005-01-01

    @@ We investigate the interface phonon assisted transition in GaAs/AlGaAs quantum cascade lasers (QCLs) by using the transfer matrix method based on the dielectric continuum model. Electron eigenvalues and eigenstates are calculated by solving Schrodinger equation and the Poisson equation self-consistently. The AlAs-like and upper GaAs-like interface phonon modes contribute most of the scattering rate. Interface phonon modes couple strongly with electrons at E2, and the magnitude of scattering rate between E2 and E1 is much larger than that between E3 and E1, which is helpful for the laser inversion between E3 and E2. The calculation can be easily applied to the design and simulation of QCLs.

  1. Hyperuniform disordered terahertz quantum cascade laser

    Science.gov (United States)

    Degl'Innocenti, R.; Shah, Y. D.; Masini, L.; Ronzani, A.; Pitanti, A.; Ren, Y.; Jessop, D. S.; Tredicucci, A.; Beere, H. E.; Ritchie, D. A.

    2016-01-01

    Laser cavities have been realized in various different photonic systems. One of the forefront research fields regards the investigation of the physics of amplifying random optical media. The random laser is a fascinating concept because, further to the fundamental research investigating light transport into complex media, it allows us to obtain non-conventional spectral distribution and angular beam emission patterns not achievable with conventional approaches. Even more intriguing is the possibility to engineer a priori the optical properties of a disordered distribution in an amplifying medium. We demonstrate here the realization of a terahertz quantum cascade laser in an isotropic hyperuniform disordered distribution exhibiting unique features, such as the presence of a photonic band gap, low threshold current density, unconventional angular emission and optical bistability.

  2. Influence of the condensate and inverse cascade on the direct cascade in wave turbulence

    CERN Document Server

    Korotkevich, A O

    2009-01-01

    During direct numerical simulation of the isotropic turbulence of surface gravity waves in the framework of Hamiltonian equations formation of the long wave background or condensate was observed. Exponents of the direct cascade spectra at the different levels of an artificial condensate suppression show a tendency to become closer to the prediction of the wave turbulence theory at lower levels of condensate. A simple qualitative explanation of the mechanism of this phenomenon is proposed.

  3. SVOM Gamma Ray Monitor

    CERN Document Server

    Dong, Yongwei; Li, Yanguo; Zhang, Yongjie; Zhang, Shuangnan

    2009-01-01

    The Space-based multi-band astronomical Variable Object Monitor (SVOM) mission is dedicated to the detection, localization and broad-band study of Gamma-Ray Bursts (GRBs) and other high-energy transient phenomena. The Gamma Ray Monitor (GRM) onboard is designed to observe the GRBs up to 5 MeV. With this instrument one of the key GRB parameter, Epeak, can be easily measured in the hard x-ray band. It can achieve a detection rate of 100 GRBs per year which ensures the scientific output of SVOM.

  4. SVOM gamma ray monitor

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The space-based multi-band astronomical Variable Object Monitor(SVOM) mission is dedicated to the detection,localization and broad-band study of gamma-ray bursts(GRBs) and other high-energy transient phenomena.The gamma ray monitor(GRM) onboard is designed to observe GRBs up to 5 MeV.With this instrument,one of the key GRB parameters,Epeak,can be easily measured in the hard X-ray band.It can achieve a detection rate of 100 GRBs per year which ensures the scientific output of SVOM.

  5. Gamma Ray Bursts

    Science.gov (United States)

    Gehrels, Neil; Meszaros, Peter

    2012-01-01

    Gamma-ray bursts (GRBs) are bright flashes of gamma-rays coming from the cosmos. They occur roughly once per day ,last typically lOs of seconds and are the most luminous events in the universe. More than three decades after their discovery, and after pioneering advances from space and ground experiments, they still remain mysterious. The launch of the Swift and Fermi satellites in 2004 and 2008 brought in a trove of qualitatively new data. In this review we survey the interplay between these recent observations and the theoretical models of the prompt GRB emission and the subsequent afterglows.

  6. Gamma-Ray Bursts

    Science.gov (United States)

    Gehrels, Neil; Mészáros, Péter

    2012-08-01

    Gamma-ray bursts (GRBs) are bright flashes of gamma rays coming from the cosmos. They occur roughly once per day, typically last for tens of seconds, and are the most luminous events in the universe. More than three decades after their discovery, and after pioneering advances from space and ground experiments, they still remain mysterious. The launch of the Swift and Fermi satellites in 2004 and 2008 brought in a trove of qualitatively new data. In this Review, we survey the interplay between these recent observations and the theoretical models of the prompt GRB emission and the subsequent afterglow.

  7. Gamma Ray Bursts

    CERN Document Server

    Gehrels, Neil; 10.1126/science.1216793

    2012-01-01

    Gamma-ray bursts (GRBs) are bright flashes of gamma-rays coming from the cosmos. They occur roughly once per day, last typically 10s of seconds and are the most luminous events in the universe. More than three decades after their discovery, and after pioneering advances from space and ground experiments, they still remain mysterious. The launch of the Swift and Fermi satellites in 2004 and 2008 brought in a trove of qualitatively new data. In this review we survey the interplay between these recent observations and the theoretical models of the prompt GRB emission and the subsequent afterglows.

  8. Wsup(+-) boson production at the e/sup +/e/sup -/,. gamma. e and. gamma gamma. colliding beams

    Energy Technology Data Exchange (ETDEWEB)

    Ginzburg, I.F.; Kotkin, G.L.; Panfil, S.L.; Serbo, V.G.

    1983-11-21

    Wsup(+-) boson production in e/sup +/e/sup -/->W/sup +/W/sup -/, ..gamma..e->W/sup +/W/sup -/, ..gamma..e->W, ..gamma gamma..->W/sup +/W/sup -/ reactions at the e/sup +/e/sup -/, ..gamma..e and ..gamma gamma.. colliding beams is considered. What physical information can be extracted from such experiments, including those with polarized beams, is discussed. Conditions of observation, are considered together with the background problems.

  9. CKM angle $\\gamma$ from LHCb

    CERN Multimedia

    Smith, Jackson

    2015-01-01

    Results of the latest $\\gamma$ combination from LHCb are presented, along with the six LHCb measurements used as inputs. In addition, the anticipated precision attainable for measuring $\\gamma$ after the LHCb Upgrade is outlined

  10. Interferon Gamma-1b Injection

    Science.gov (United States)

    Interferon gamma-1b injection is used to reduce the frequency and severity of serious infections in people ... with severe, malignant osteopetrosis (an inherited bone disease). Interferon gamma-1b is in a class of medications ...

  11. CONSTRAINING THE EMISSIVITY OF ULTRAHIGH ENERGY COSMIC RAYS IN THE DISTANT UNIVERSE WITH THE DIFFUSE GAMMA-RAY EMISSION

    International Nuclear Information System (INIS)

    Ultrahigh cosmic rays (UHECRs) with energies ∼> 1019 eV emitted at cosmological distances will be attenuated by cosmic microwave and infrared background radiation through photohadronic processes. Lower energy extragalactic cosmic rays (∼1018-1019 eV) can only travel a linear distance smaller than ∼Gpc in a Hubble time due to the diffusion if the extragalactic magnetic fields are as strong as nano-Gauss. These prevent us from directly observing most of the UHECRs in the universe, and thus the observed UHECR intensity reflects only the emissivity in the nearby universe within hundreds of Mpc. However, UHECRs in the distant universe, through interactions with the cosmic background photons, produce UHE electrons and gamma rays that in turn initiate electromagnetic cascades on cosmic background photons. This secondary cascade radiation forms part of the extragalactic diffuse GeV-TeV gamma-ray radiation and, unlike the original UHECRs, is observable. Motivated by new measurements of extragalactic diffuse gamma-ray background radiation by Fermi/Large Area Telescope, we obtained upper limit placed on the UHECR emissivity in the distant universe by requiring that the cascade radiation they produce not exceed the observed levels. By comparison with the gamma-ray emissivity of candidate UHECR sources (such as gamma-ray bursts (GRBs) and active galactic nuclei) at high redshifts, we find that the obtained upper limit for a flat proton spectrum is ≅ 101.5 times larger than the gamma-ray emissivity in GRBs and ≅ 10 times smaller than the gamma-ray emissivity in BL Lac objects. In the case of iron nuclei composition, the derived upper limit of UHECR emissivity is a factor of 3-5 times higher. Robust upper limit on the cosmogenic neutrino flux is further obtained, which is marginally reachable by the Icecube detector and the next-generation detector JEM-EUSO.

  12. Proprioceptive evoked gamma oscillations

    DEFF Research Database (Denmark)

    Arnfred, S.M.; Hansen, Lars Kai; Parnas, J.;

    2007-01-01

    A proprioceptive stimulus consisting of a weight change of a handheld load has recently been shown to elicit an evoked potential. Previously, somatosensory gamma oscillations have only been evoked by electrical stimuli. We conjectured that a natural proprioceptive stimulus also would be able...

  13. The shifting gamma perception

    NARCIS (Netherlands)

    Besuijen, J.

    2005-01-01

    True to life, color display and color management depend on a proper technical model of the display used. Current gamma models and fitting procedures are not accurate in modeling the lower part of the tone reproduction curve. The GOG- and GOGO-model used in color management standards tend to clip the

  14. Proprioceptive evoked gamma oscillations

    DEFF Research Database (Denmark)

    Arnfred, Sidse M; Hansen, Lars Kai; Parnas, Josef;

    2007-01-01

    A proprioceptive stimulus consisting of a weight change of a handheld load has recently been shown to elicit an evoked potential. Previously, somatosensory gamma oscillations have only been evoked by electrical stimuli. We conjectured that a natural proprioceptive stimulus also would be able to...

  15. Industrial radiography. Gamma radiography

    International Nuclear Information System (INIS)

    Informations are given on gamma radiodefectology regulations, entire references and main dispositions applicable to each state of the European Economic Community. The content includes previous arrangements for source acquisition, holding and use of the sources, transport, accidents, civil liability of the source holder, person insurance against radiation hazards and contamination, property insurance, penal liability of the source holder

  16. Chemist's gamma-ray table

    International Nuclear Information System (INIS)

    An edited listing of gamma-ray information has been prepared. Prominent gamma rays originating from nuclides with half lives long enough to be seen in radiochemical experiments are included. Information is ordered by nuclide in one section and by energy in a second section. This shorter listing facilitates identification of nuclides responsible for gamma rays observed in experiments

  17. Measurement of {\\eta} meson production in {\\gamma}{\\gamma} interactions and {\\Gamma}({\\eta}-->{\\gamma}{\\gamma}) with the KLOE detector

    CERN Document Server

    :,; Badoni, D; Balwierz-Pytko, I; Bencivenni, G; Bini, C; Bloise, C; Bossi, F; Branchini, P; Budano, A; Balkestaahl, L Caldeira; Capon, G; Ceradini, F; Ciambrone, P; Czerwinski, E; Dane, E; De Lucia, E; De Robertis, G; De Santis, A; Di Domenico, A; Di Donato, C; Di Salvo, R; Domenici, D; Erriquez, O; Fanizzi, G; Fantini, A; Felici, G; Fiore, S; Franzini, P; Gauzzi, P; Giardina, G; Giovannella, S; Gonnella, F; Graziani, E; Happacher, F; Heijkenskj, L; Hoistad, B; Iafolla, L; Jacewicz, M; Johansson, T; Kupsc, A; Lee-Franzini, J; Leverington, B; Loddo, F; Loffredo, S; Mandaglio, G; Martemianov, M; Martini, M; Mascolo, M; Messi, R; Miscetti, S; Morello, G; Moricciani, D; Moskal, P; Nguyen, F; Passeri, A; Patera, V; Longhi, I Prado; Ranieri, A; Redmer, C F; Santangelo, P; Sarra, I; Schioppa, M; Sciascia, B; Silarski, M; Taccini, C; Tortora, L; Venanzoni, G; Wislicki, W; Wolke, M; Zdebik, J

    2012-01-01

    We present a measurement of {\\eta} meson production in photon-photon interactions produced by electron-positron beams colliding with \\sqrt{s}=1 GeV. The measurement is done with the KLOE detector at the \\phi-factory DA{\\Phi}NE with an integrated luminosity of 0.24 fb^{-1}. The e^+e^- --> e^+e^-{\\eta} cross section is measured without detecting the outgoing electron and positron, selecting the decays {\\eta}-->{\\pi}^+{\\pi}^-{\\pi}^0 and {\\eta}-->{\\pi}^0{\\pi}^0{\\pi}^0. The most relevant background is due to e^+e^- --> {\\eta}{\\gamma} when the monochromatic photon escapes detection. The cross section for this process is measured as {\\sigma}(e^+e^- -->{\\eta}{\\gamma}) = (856 \\pm 8_{stat} \\pm 16_{syst}) pb. The combined result for the e^+e^- -->e^+e^-{\\eta} cross section is {\\sigma}(e^+e^- -->e^+e^-{\\eta}) = (32.72 \\pm 1.27_{stat} \\pm 0.70_{syst}) pb. From this we derive the partial width {\\Gamma}({\\eta}-->{\\gamma}{\\gamma}) = (520 \\pm 20_{stat} \\pm 13_{syst}) eV. This is in agreement with the world average and is the ...

  18. Gamma-ray performance of the GAMMA-400 detector

    CERN Document Server

    Cumani, P; Bonvicini, V; Topchiev, N P; Adriani, O; Aptekar, R L; Arkhangelskaja, I V; Arkhangelskiy, A I; Bergstrom, L; Berti, E; Bigongiari, G; Bobkov, S G; Boezio, M; Bogomolov, E A; Bonechi, S; Bongi, M; Bottai, S; Castellini, G; Cattaneo, P W; Dedenko, G L; De Donato, C; Dogiel, V A; Gorbunov, M S; Gusakov, Yu V; Hnatyk, B I; Kadilin, V V; Kaplin, V A; Kaplun, A A; Kheymits, M D; Korepanov, V E; Larsson, J; Leonov, A A; Loginov, V A; Longo, F; Maestro, P; Marrocchesi, P S; Menshenin, A L; Mikhailov, V V; Mocchiutti, E; Moiseev, A A; Mori, N; Moskalenko, I V; Naumov, P Yu; Papini, P; Pearce, M; Picozza, P; Popov, A V; Rappoldi, A; Ricciarini, S; Runtso, M F; Ryde, F; Sarkar, R; Serdin, O V; Sparvoli, R; Spillantini, P; Suchkov, S I; Tavani, M; Taraskin, A A; Tiberio, A; Tyurin, E M; Ulanov, M V; Vacchi, A; Vannuccini, E; Vasilyev, G I; Yurkin, Yu T; Zampa, N; Zirakashvili, V N; Zverev, V G

    2015-01-01

    GAMMA-400 is a new space mission, designed as a dual experiment, capable to study both high energy gamma rays (from $\\sim$100 MeV to few TeV) and cosmic rays (electrons up to 20 TeV and nuclei up to $\\sim$10$^{15}$ eV). The full simulation framework of GAMMA-400 is based on the Geant4 toolkit. The details of the gamma-ray reconstruction pipeline in the three main instruments (Tracker, Imaging Calorimeter, Homogeneous Calorimeter) will be outlined. The performance of GAMMA-400 (PSF, effective area and sensitivity) have been obtained using this framework. The most updated results on them will be shown.

  19. Proton Pump Inhibitors and the Prescribing Cascade.

    Science.gov (United States)

    Rababa, Mohammad; Al-Ghassani, Amal Ali; Kovach, Christine R; Dyer, Elaine M

    2016-04-01

    HOW TO OBTAIN CONTACT HOURS BY READING THIS ARTICLE Instructions 1.3 contact hours will be awarded by Villanova University College of Nursing upon successful completion of this activity. A contact hour is a unit of measurement that denotes 60 minutes of an organized learning activity. This is a learner-based activity. Villanova University College of Nursing does not require submission of your answers to the quiz. A contact hour certificate will be awarded once you register, pay the registration fee, and complete the evaluation form online at http://goo.gl/gMfXaf. To obtain contact hours you must: 1. Read the article, "Proton Pump Inhibitors and the Prescribing Cascade" found on pages 23-31, carefully noting any tables and other illustrative materials that are included to enhance your knowledge and understanding of the content. Be sure to keep track of the amount of time (number of minutes) you spend reading the article and completing the quiz. 2. Read and answer each question on the quiz. After completing all of the questions, compare your answers to those provided within this issue. If you have incorrect answers, return to the article for further study. 3. Go to the Villanova website listed above to register for contact hour credit. You will be asked to provide your name; contact information; and a VISA, MasterCard, or Discover card number for payment of the $20.00 fee. Once you complete the online evaluation, a certificate will be automatically generated. This activity is valid for continuing education credit until March 31, 2019. CONTACT HOURS This activity is co-provided by Villanova University College of Nursing and SLACK Incorporated. Villanova University College of Nursing is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's Commission on Accreditation. ACTIVITY OBJECTIVES 1. Describe the prescribing cascade of proton pump inhibitors (PPI) in nursing home residents. 2. Identify the statistically

  20. Probabilistic analysis of cascade failure dynamics in complex network

    Science.gov (United States)

    Zhang, Ding-Xue; Zhao, Dan; Guan, Zhi-Hong; Wu, Yonghong; Chi, Ming; Zheng, Gui-Lin

    2016-11-01

    The impact of initial load and tolerance parameter distribution on cascade failure is investigated. By using mean field theory, a probabilistic cascade failure model is established. Based on the model, the damage caused by certain attack size can be predicted, and the critical attack size is derived by the condition of cascade failure end, which ensures no collapse. The critical attack size is larger than the case of constant tolerance parameter for network of random distribution. Comparing three typical distributions, simulation results indicate that the network whose initial load and tolerance parameter both follow Weibull distribution performs better than others.

  1. The finite mass calculations for Gamma Gamma --> L+ L- Gamma process

    OpenAIRE

    Makarenko, V. V.; T.V. Shishkina

    2003-01-01

    The process $\\gamma\\gamma\\to l^+ l^- \\gamma$ will be used for the photon beams luminosity measurement when the total angular momentum of colliding photons equals zero. The previous studies of this process were performed in the chiral limit. But the mass contribution should be taken into account.

  2. Probing the energy cascade of convective turbulence.

    Science.gov (United States)

    Kunnen, R P J; Clercx, H J H

    2014-12-01

    The existence of a buoyancy-dominated scaling range in convective turbulence is a longstanding open question. We investigate this issue by considering the scale-by-scale energy budget in direct numerical simulations of Rayleigh-Bénard convection. We try to minimize the so-called Bolgiano length scale, the length scale at which buoyancy becomes dominant for scaling. Therefore, we deliberately choose modest Rayleigh numbers Ra=2.5×10(6) and 2.5×10(7). The budget reveals that buoyant forcing, turbulent energy transfer, and dissipation are contributing significantly over a wide range of scales. Thereby neither Kolmogorov-like (balance of turbulent transfer and dissipation) nor Bolgiano-Obukhov-like scaling (balance of turbulent transfer and buoyancy) is expected in the structure functions, which indeed reveal inconclusive scaling behavior. Furthermore, we consider the calculation of the Bolgiano length scale. To account for correlations between the dissipation rates of kinetic energy and thermal variance we propose to average the Bolgiano length scale directly. This gives an estimate, which is one order of magnitude larger than the previous estimate, and actually larger than the domain itself. Rather than studying the scaling of structure functions, we propose that the use of scale-by-scale energy budgets resolving anisotropic contributions is appropriate to consider the energy cascade mechanisms in turbulent convection.

  3. Inverse turbulent cascade in swarming sperm

    Science.gov (United States)

    Creppy, Adama; Praud, Olivier; Druart, Xavier; Kohnke, Philippa; Plouraboue, Franck; Inra, Cnrs, Umr, F-37380 Nouzilly, France Team; Université de Toulouse, Inpt, Ups, Imft, Umr 5502, France Team

    2014-11-01

    Collective motion of self-sustained swarming flows has recently provided examples of small scale turbulence arising where viscosity effects are dominant. We report the first observation of an universal inverse enstrophy cascade in concentrated swarming sperm consistent with a body of evidence built from various independent measurements. We found a well-defined k-3 power-law decay of velocity field power-spectrum and relative dispersion of small beads consistent with theoretical predictions in two-dimensional turbulence. Concentrated living sperm displays long-range, correlated whirlpool structures the size of which provides turbulence's integral scale. We propose a consistent explanation for this quasi-two-dimensional turbulence based on self-structured laminated flow forced by steric interaction and alignment, a state of active matter that we call ``swarming liquid crystal.'' We develop scaling arguments consistent with this interpretation. The implication of multi-scale collective dynamics of sperm's collective motility for fertility assessment is discussed. This work has been supported by the French Agence Nationale pour la Recherche (ANR) in the frame of the Contract MOTIMO (ANR-11-MONU-009-01). We thank Pierre Degond, Eric Climent, Laurent Lacaze and Frédéric Moulin for interesting discussions.

  4. Cascading reminiscence bumps in popular music.

    Science.gov (United States)

    Krumhansl, Carol Lynne; Zupnick, Justin Adam

    2013-10-01

    Autobiographical memories are disproportionately recalled for events in late adolescence and early adulthood, a phenomenon called the reminiscence bump. Previous studies on music have found autobiographical memories and life-long preferences for music from this period. In the present study, we probed young adults' personal memories associated with top hits over 5-and-a-half decades, as well as the context of their memories and their recognition of, preference for, quality judgments of, and emotional reactions to that music. All these measures showed the typical increase for music released during the two decades of their lives. Unexpectedly, we found that the same measures peaked for the music of participants' parents' generation. This finding points to the impact of music in childhood and suggests that these results reflect the prevalence of music in the home environment. An earlier peak occurred for 1960s music, which may be explained by its quality or by its transmission through two generations. We refer to this pattern of musical cultural transmission over generations as cascading reminiscence bumps. PMID:24006129

  5. Astronomical Forcing of Salt Marsh Biogeochemical Cascades

    Science.gov (United States)

    Morris, J. T.; Sundberg, K.

    2008-12-01

    Astronomically forced changes in the hydroperiod of a salt marsh affect the rate of marsh primary production leading to a biogeochemical cascade. For example, salt marsh primary production and biogeochemical cycles in coastal salt marshes are sensitive to the 18.6-year lunar nodal cycle, which alters the tidal amplitude by about 5 cm. For marshes that are perched high in the tidal frame, a relatively small increase in tidal amplitude and flooding lowers sediment salinity and stimulates primary production. Porewater sulfide concentrations are positively correlated with tidal amplitude and vary on the same cycle as primary production. Soluble reactive phosphate and ammonium concentrations in pore water also vary on this 18.6- year cycle. Phosphate likely responds to variation in the reaction of sulfide with iron-phosphate compounds, while the production of ammonium in sediments is coupled to the activity of diazotrophs that are carbon- limited and, therefore, are regulated by primary productivity. Ammonium also would accumulate when sulfides block nitrification. These dependencies work as a positive feedback between primary production and nutrient supply and are predictive of the near-term effects of sea-level rise.

  6. Cascading reminiscence bumps in popular music.

    Science.gov (United States)

    Krumhansl, Carol Lynne; Zupnick, Justin Adam

    2013-10-01

    Autobiographical memories are disproportionately recalled for events in late adolescence and early adulthood, a phenomenon called the reminiscence bump. Previous studies on music have found autobiographical memories and life-long preferences for music from this period. In the present study, we probed young adults' personal memories associated with top hits over 5-and-a-half decades, as well as the context of their memories and their recognition of, preference for, quality judgments of, and emotional reactions to that music. All these measures showed the typical increase for music released during the two decades of their lives. Unexpectedly, we found that the same measures peaked for the music of participants' parents' generation. This finding points to the impact of music in childhood and suggests that these results reflect the prevalence of music in the home environment. An earlier peak occurred for 1960s music, which may be explained by its quality or by its transmission through two generations. We refer to this pattern of musical cultural transmission over generations as cascading reminiscence bumps.

  7. Cascade category-aware visual search.

    Science.gov (United States)

    Zhang, Shiliang; Tian, Qi; Huang, Qingming; Gao, Wen; Rui, Yong

    2014-06-01

    Incorporating image classification into image retrieval system brings many attractive advantages. For instance, the search space can be narrowed down by rejecting images in irrelevant categories of the query. The retrieved images can be more consistent in semantics by indexing and returning images in the relevant categories together. However, due to their different goals on recognition accuracy and retrieval scalability, it is hard to efficiently incorporate most image classification works into large-scale image search. To study this problem, we propose cascade category-aware visual search, which utilizes weak category clue to achieve better retrieval accuracy, efficiency, and memory consumption. To capture the category and visual clues of an image, we first learn category-visual words, which are discriminative and repeatable local features labeled with categories. By identifying category-visual words in database images, we are able to discard noisy local features and extract image visual and category clues, which are hence recorded in a hierarchical index structure. Our retrieval system narrows down the search space by: 1) filtering the noisy local features in query; 2) rejecting irrelevant categories in database; and 3) preforming discriminative visual search in relevant categories. The proposed algorithm is tested on object search, landmark search, and large-scale similar image search on the large-scale LSVRC10 data set. Although the category clue introduced is weak, our algorithm still shows substantial advantages in retrieval accuracy, efficiency, and memory consumption than the state-of-the-art.

  8. Compression-absorption cascade refrigeration system

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Seara, Jose; Sieres, Jaime; Vazquez, Manuel [Area de Maquinas y Motores Termicos, Escuela Tecnica Superior de Ingenieros Industriales, Universidade de Vigo, Campus Lagoas-Marcosende, 9, 36200 Vigo (Spain)

    2006-04-01

    This paper describes the study carried out to analyse a refrigeration system in cascade with a compression system at the low temperature stage and an absorption system at the high temperature stage to generate cooling at low temperatures, as well as the possibility of powering it by means of a cogeneration system. CO{sub 2} and NH{sub 3} have been considered as refrigerants in the compression stage and the pair NH{sub 3}-H{sub 2}O in the absorption stage. The analysis has been realized by means of a mathematical model of the refrigeration system implemented in a computer program and taking into account the characteristic operating conditions of a cogeneration system with gas engines. The paper presents the results obtained regarding the performance of the refrigeration system and the adaptability between the power requirements of the refrigeration system and the power supplied by the cogeneration system taking into account the present Spanish Regulations about the use of cogeneration systems. [Author].

  9. Quantum cascade laser Kerr frequency comb

    CERN Document Server

    Lecaplain, Caroline; Lucas, Erwan; Jost, John D; Kippenberg, Tobias J

    2015-01-01

    The mid-infrared (mid-IR) regime (typically the wavelength regime of $\\lambda \\sim 2.5-20 \\ \\mathrm{\\mu m}$) is an important spectral range for spectroscopy as many molecules have their fundamental rotational-vibrational absorption in this band. Recently optical frequency combs based on optical microresonators ("Kerr" combs) at the onset of the mid-IR region have been generated using crystalline resonators and integrated planar silicon micro-resonators. Here we extend for the first time Kerr combs deep into the mid-IR i.e. the 'molecular fingerprint' region. This is achieved by combining an ultra high quality (Q) factor mid-IR microresonator based on crystalline $\\mathrm{MgF_{2}}$ with the quantum cascade laser (QCL) technology. Using a tapered chalgogenide (ChG) fiber and a QCL continuous wave pump laser, frequency combs at $\\lambda\\sim 4.4\\ \\mathrm{\\mu m}$ (i.e. 2270cm$^{-1}$) are generated, that span over 600nm (i.e. 300cm$^{-1}$) in bandwidth, with a mode spacing of 14.3GHz (0.5cm$^{-1}$), corresponding t...

  10. Precise measurement of {gamma}(K{yields}e {nu}({gamma}))/{gamma}(K{yields}{mu} {nu}({gamma})) and study of K{yields}e {nu} {gamma}

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosino, F.; Massarotti, P.; Meola, S.; Napolitano, M. [Dipartimento di Scienze Fisiche dell' Universita ' ' Federico II' ' , Napoli (Italy); INFN Sezione di Napoli, Napoli (Italy); Antonelli, A.; Antonelli, M.; Bencivenni, G.; Bloise, C.; Bossi, F.; Capon, G.; Capussela, T.; Ciambrone, P.; De Lucia, E.; De Simone, P.; Dreucci, M.; Felici, G.; Gatti, C.; Giovannella, S.; Jacewicz, M.; Lanfranchi, G.; Miscetti, S.; Moulson, M.; Murtas, F.; Palutan, M.; Santangelo, P.; Sciascia, B.; Sibidanov, A.; Spadaro, T.; Venanzoni, G. [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); Archilli, F. [Dipartimento di Fisica dell' Universita ' ' Tor Vergata' ' , Rome (Italy); INFN Sezione di Roma Tor Vergata, Rome (Italy); Beltrame, P.; Denig, A.; Mueller, S. [Johannes Gutenberg-Universitaet, Institut fuer Kernphysik, Mainz (Germany); Bini, C.; De Santis, A.; De Zorzi, G.; Di Domenico, A.; Fiore, S.; Franzini, P.; Gauzzi, P. [Dipartimento di Fisica dell' Universita ' ' La Sapienza' ' , Rome (Italy); INFN Sezione di Roma, Rome (Italy); Bocchetta, S.; Ceradini, F.; Di Micco, B.; Nguyen, F. [Dipartimento di Fisica dell' Universita ' ' Roma Tre' ' , Rome (Italy); INFN Sezione di Roma Tre, Rome (Italy); Branchini, P.; Graziani, E.; Passeri, A.; Tortora, L. [INFN Sezione di Roma Tre, Rome (Italy); Capriotti, D. [Dipartimento di Fisica dell' Universita ' ' Roma Tre' ' , Rome (Italy); Di Donato, C. [INFN Sezione di Napoli, Napoli (Italy); Kulikov, V. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Lee-Franzini, J. [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); State University of New York, Physics Department, Stony Brook (United States); Martini, M.; Patera, V.; Versaci, R. [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); Dipartimento di Energetica dell' Universita ' ' La Sapienza' ' , Rome (Italy); Valente, P. [INFN Sezione di Roma, Rome (Italy)

    2009-12-15

    We present a precise measurement of the ratio R{sub K}={gamma}(K{yields}e{nu}({gamma}))/{gamma}(K{yields}{mu}{nu}({gamma})) and a study of the radiative process K{yields}e{nu}{gamma}, performed with the KLOE detector. The results are based on data collected at the Frascati e{sup +}e{sup -} collider DA {phi}NE for an integrated luminosity of 2.2 fb{sup -1}. We find R{sub K}=(2.493{+-}0.025{sub stat}{+-}0.019{sub syst}) x 10{sup -5}, in agreement with the Standard Model expectation. This result is used to improve constraints on parameters of the Minimal Supersymmetric Standard Model with lepton flavor violation. We also measured the differential decay rate d {gamma}(K{yields}e{nu}{gamma})/dE{sub {gamma}} for photon energies 10gamma}}<250 MeV. Results are compared with predictions from theory. (orig.)

  11. Terahertz Quantum Cascade Laser Based 3D Imaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — LongWave Photonics proposes a terahertz quantum-cascade laser based swept-source optical coherence tomography (THz SS-OCT) system for single-sided, 3D,...

  12. Noise properties and cascadability of SOA-EA regenerators

    DEFF Research Database (Denmark)

    Öhman, Filip; Bischoff, Svend; Tromborg, Bjarne;

    2002-01-01

    We suggest and analyse a new device containing concatenated pairs of semiconductor optical amplifiers (SOAs) and electroabsorption modulators (EAs). The device has regenerative properties and improves the cascadability of optical fibre links....

  13. Enantiomer separation in a cascaded micellar-enhanced ultrafiltration system

    NARCIS (Netherlands)

    Overdevest, P.E.M.; Hoenders, M.H.J.; Riet, van 't K.; Padt, van der A.; Keurentjes, J.T.F.

    2002-01-01

    The increasing demand for optically pure compounds (enantiomers) stimulates the development of new enantiomer separation processes on an industrial scale. The separation of enantiomers by ultrafiltration of enantioselective micelles was studied in a cascaded system. The feasibility of this separatio

  14. Influence of Blade Chordwise Lean on Development of Cascade Losses

    Institute of Scientific and Technical Information of China (English)

    HanWanjin; HuangHongyan; 等

    1996-01-01

    An experimetal investigation was carried out on the effect of blade chordwise lean on the losse in highly loaded rectangular turbine cascades,Datailed measurements include 10 traverses from upstream to downstream of the cascades with five-hole spherical probes.Compared with the experimental data of the coventional Straight and pitchwise lean blades under the same conditions,it is shown that the effect of chordwise lean on the development of the cascade losses is similar to that of pitchwise lean.However,the chordwise lean produces smaller streamwise adverse pressure gradients near both endwalls and a smaller spanwise negative one starting from the actute angle side in the first part of the passages in chordwise lean cascade,thereby the saddle point separations and intensities of the passage vortices are weakened and the secondary vorte losses are cut down notably.

  15. On periodic orbits in discrete-time cascade systems

    Directory of Open Access Journals (Sweden)

    Huimin Li

    2006-01-01

    Full Text Available We present some results on existence, minimum period, number of periodic orbits, and stability of periodic orbits in discrete-time cascade systems. Some examples are presented to illustrate these results.

  16. Mutually independent cascades in anisotropic soap-film turbulence

    Science.gov (United States)

    Liu, Chien-Chia; Gioia, Gustavo; Chakraborty, Pinaki

    2015-03-01

    Computational, experimental and field data amassed to date indicate that in 2D turbulence the spectrum of longitudinal velocity fluctuations, E11 (k1) , and the spectrum of transverse velocity fluctuations, E22 (k1) , correspond always to the same cascade, consistent with isotropy, so that E11 (k1) ~k-α and E22 (k1) ~k-α , where the ``spectral exponent'' α is either 5/3 (for the inverse-energy cascade) or 3 (for the enstrophy cascade). Here, we carry out experiments on turbulent 2D soap-film flows in which E11 (k1) ~k - 5 / 3 and E22 (k1) ~k-3 , as if two mutually independent cascades were concurrently active within the same flow. To our knowledge, this species of spectrum has never been observed or predicted theoretically. Our finding might open up new vistas in the understanding of turbulence.

  17. The flow analysis of supercavitating cascade by linear theory

    Energy Technology Data Exchange (ETDEWEB)

    Park, E.T. [Sung Kyun Kwan Univ., Seoul (Korea, Republic of); Hwang, Y. [Seoul National Univ., Seoul (Korea, Republic of)

    1996-06-01

    In order to reduce damages due to cavitation effects and to improve performance of fluid machinery, supercavitation around the cascade and the hydraulic characteristics of supercavitating cascade must be analyzed accurately. And the study on the effects of cavitation on fluid machinery and analysis on the performances of supercavitating hydrofoil through various elements governing flow field are critically important. In this study comparison of experiment results with the computed results of linear theory using singularity method was obtainable. Specially singularity points like sources and vortexes on hydrofoil and freestreamline were distributed to analyze two dimensional flow field of supercavitating cascade, and governing equations of flow field were derived and hydraulic characteristics of cascade were calculated by numerical analysis of the governing equations. 7 refs., 6 figs.

  18. Dynamic Modeling of Cascading Failure in Power Systems

    CERN Document Server

    Song, Jiajia; Ghanavati, Goodarz; Hines, Paul D H

    2014-01-01

    The modeling of cascading failure in power systems is difficult because of the many different mechanisms involved; no single model captures all of these mechanisms. Understanding the relative importance of these different mechanisms is an important step in choosing which mechanisms need to be modeled for particular types of cascading failure analysis. This work presents a dynamic simulation model of both power networks and protection systems, which can simulate a wider variety of cascading outage mechanisms, relative to existing quasi-steady state (QSS) models. The model allows one to test the impact of different load models and protections on cascading outage sizes. This paper describes each module of the developed dynamic model and demonstrates how different mechanisms interact. In order to test the model we simulated a batch of randomly selected $N-2$ contingencies for several different static load configurations, and found that the distribution of blackout sizes and event lengths from the proposed dynamic...

  19. Cascading failures in local-world evolving networks

    Institute of Scientific and Technical Information of China (English)

    Zhe-jing BAO; Yi-jia CAO

    2008-01-01

    The local-world (LW) evolving network model shows a transition for the degree distribution between the exponential and power-law distributions, depending on the LW size. Cascading failures under intentional attacks in LW network models with different LW sizes were investigated using the cascading failures load model. We found that the LW size has a significant impact on the network's robustness against deliberate attacks. It is much easier to trigger cascading failures in LW evolving networks with a larger LW size. Therefore, to avoid cascading failures in real networks with local preferential attachment such as the Internet, the World Trade Web and the multi-agent system, the LW size should be as small as possible.

  20. Statistical analysis of cascading failures in power grids

    Energy Technology Data Exchange (ETDEWEB)

    Chertkov, Michael [Los Alamos National Laboratory; Pfitzner, Rene [Los Alamos National Laboratory; Turitsyn, Konstantin [Los Alamos National Laboratory

    2010-12-01

    We introduce a new microscopic model of cascading failures in transmission power grids. This model accounts for automatic response of the grid to load fluctuations that take place on the scale of minutes, when optimum power flow adjustments and load shedding controls are unavailable. We describe extreme events, caused by load fluctuations, which cause cascading failures of loads, generators and lines. Our model is quasi-static in the causal, discrete time and sequential resolution of individual failures. The model, in its simplest realization based on the Directed Current description of the power flow problem, is tested on three standard IEEE systems consisting of 30, 39 and 118 buses. Our statistical analysis suggests a straightforward classification of cascading and islanding phases in terms of the ratios between average number of removed loads, generators and links. The analysis also demonstrates sensitivity to variations in line capacities. Future research challenges in modeling and control of cascading outages over real-world power networks are discussed.

  1. Cascade Structure of Digital Predistorter for Power Amplifier Linearization

    Directory of Open Access Journals (Sweden)

    E. B. Solovyeva

    2015-12-01

    Full Text Available In this paper, a cascade structure of nonlinear digital predistorter (DPD synthesized by the direct learning adaptive algorithm is represented. DPD is used for linearization of power amplifier (PA characteristic, namely for compensation of PA nonlinear distortion. Blocks of the cascade DPD are described by different models: the functional link artificial neural network (FLANN, the polynomial perceptron network (PPN and the radially pruned Volterra model (RPVM. At synthesis of the cascade DPD there is possibility to overcome the ill conditionality problem due to reducing the dimension of DPD nonlinear operator approximation. Results of compensating nonlinear distortion in Wiener–Hammerstein model of PA at the GSM–signal with four carriers are shown. The highest accuracy of PA linearization is produced by the cascade DPD containing PPN and RPVM.

  2. Phase seeding of a terahertz quantum cascade laser

    OpenAIRE

    Oustinov, Dimitri; Jukam, Nathan; Rungsawang, Rakchanok; Madéo, Julien; Barbieri, Stefano; Filloux, Pascal; Sirtori, Carlo; Marcadet, Xavier; Tignon, Jérôme; Dhillon, Sukhdeep

    2010-01-01

    International audience The amplification of spontaneous emission is used to initiate laser action. Since the phase of spontaneous emission is random, the phase of the coherent laser emission (the carrier phase) will also be random each time laser action begins. This prevents phase resolved detection of the laser field. Here, we demonstrate how the carrierphase can be fixed in a semiconductor laser: a quantum cascade laser. This is performed by injection seeding a quantum cascade laser with...

  3. Hydrothermal monitoring data from the Cascade Range, northwestern United States

    Science.gov (United States)

    Ingebritsen, Steven E.; Gelwick, Katrina D.; Randolph-Flagg, Noah G.; Crankshaw, Ilana M.; Lundstrom, Elizabeth A.; McCulloch, Callum L.; Murveit, Anna M.; Newman, Alice C.; Mariner, Robert H.; Bergfeld, D.; Tucker, Dave S.; Schmidt, Mariek E.; Spicer, Kurt R.; Mosbrucker, Adam; Evans, William C.

    2013-01-01

    This database serves as a repository for hydrothermal-monitoring data collected at 25 sites in the U.S. portion of the Cascade Range volcanic arc. These data are intended to quantify baseline hydrothermal variability at most (10 of 12) of the highest-risk volcanoes in the Cascades, as defined by the U.S. Geological Survey’s (USGS’) National Volcanic Early Warning System (NVEWS) report (Ewert and others, 2005).

  4. Cascade Decays of Triplet Higgs Bosons at LEP2

    CERN Document Server

    Akeroyd, A G

    1998-01-01

    We study the Georgi-Machacek two triplet, one doublet model in the context of LEP2, and show that cascade decays of Higgs bosons to lighter Higgs bosons and a virtual vector boson may play a major role. Such decays would allow the Higgs bosons of this model to escape current searches, and in particular are of great importance for the members of the five-plet which will always decay to the three-plet giving rise to cascade signatures.

  5. Pair cascades in the magnetospheres of strongly magnetized neutron stars

    Science.gov (United States)

    Medin, Zach; Lai, Dong

    2010-08-01

    We present numerical simulations of electron-positron pair cascades in the magnetospheres of magnetic neutron stars for a wide range of surface fields (Bp = 1012-1015 G), rotation periods (0.1-10 s) and field geometries. This has been motivated by the discovery in recent years of a number of radio pulsars with inferred magnetic fields comparable to those of magnetars. Evolving the cascade generated by a primary electron or positron after it has been accelerated in the inner gap of the magnetosphere, we follow the spatial development of the cascade until the secondary photons and electron-positron pairs leave the magnetosphere, and we obtain the pair multiplicity and the energy spectra of the cascade pairs and photons under various conditions. Going beyond previous works, which were restricted to weaker fields (B crudely treated before, including photon splitting with the correct selection rules for photon polarization modes, one-photon pair production into low Landau levels for the e+/-, and resonant inverse Compton scattering from polar cap hotspots. We find that even for B >> BQ = 4 × 1013 G, photon splitting has a small effect on the multiplicity of the cascade since a majority of the photons in the cascade cannot split. One-photon decay into e+ e- pairs at low Landau levels, however, becomes the dominant pair production channel when B >~ 3 × 1012 G; this tends to suppress synchrotron radiation so that the cascade can develop only at a larger distance from the stellar surface. Nevertheless, we find that the total number of pairs and their energy spectrum produced in the cascade depend mainly on the polar cap voltage BpP-2, and are weakly dependent on Bp (and P) alone. We discuss the implications of our results for the radio pulsar death line and for the hard X-ray emission from magnetized neutron stars.

  6. Cascaded Soliton Compression of Energetic Femtosecond Pulses at 1030 nm

    DEFF Research Database (Denmark)

    Bache, Morten; Zhou, Binbin

    2012-01-01

    We discuss soliton compression with cascaded second-harmonic generation of energetic femtosecond pulses at 1030 nm. We discuss problems encountered with soliton compression of long pulses and show that sub-10 fs compressed pulses can be achieved.......We discuss soliton compression with cascaded second-harmonic generation of energetic femtosecond pulses at 1030 nm. We discuss problems encountered with soliton compression of long pulses and show that sub-10 fs compressed pulses can be achieved....

  7. INFORMATION CASCADES WITH FINANCIAL MARKET PROFESSIONALS: AN EXPERIMENTAL STUDY

    OpenAIRE

    Jonathan E. Alevy; Haigh, Michael S.; List, John A

    2003-01-01

    In settings where there is imperfect information about an underlying state of nature, but where inferences are made sequentially and are publicly observable, information cascades can lead to rational herding. Cascade phenomena may be seen in a variety of areas including technology adoption, financial market behavior, as well as in social processes such as mate selection or fads and fashions. Theories of rational herding have found a natural testing ground in experimental environments since th...

  8. Linewidth and tuning characteristics of terahertz quantum cascade lasers.

    Science.gov (United States)

    Barkan, A; Tittel, F K; Mittleman, D M; Dengler, R; Siegel, P H; Scalari, G; Ajili, L; Faist, J; Beere, H E; Linfield, E H; Davies, A G; Ritchie, D A

    2004-03-15

    We have measured the spectral linewidths of three continuous-wave quantum cascade lasers operating at terahertz frequencies by heterodyning the free-running quantum cascade laser with two far-infrared gas lasers. Beat notes are detected with a GaAs diode mixer and a microwave spectrum analyzer, permitting very precise frequency measurements and giving instantaneous linewidths of less than -30 kHz. Characteristics are also reported for frequency tuning as the injection current is varied.

  9. Analysis of noise suppression in cascaded all-optical regenerators

    DEFF Research Database (Denmark)

    Mørk, Jesper; Öhman, Filip; Bischoff, Svend

    2002-01-01

    We derive an approximate analytical expression for the BER of cascaded links with all-optical regenerators and use it for performing a general analysis of the interplay between noise and the non-linearity of the regenerator characteristic.......We derive an approximate analytical expression for the BER of cascaded links with all-optical regenerators and use it for performing a general analysis of the interplay between noise and the non-linearity of the regenerator characteristic....

  10. Critical Boundary of Cascaded Quadratic Soliton Compression in PPLN

    DEFF Research Database (Denmark)

    Guo, Hairun; Zeng, Xianglong; Zhou, Binbin;

    2012-01-01

    Cascaded quadratic soliton compression in PPLN is investigated and a general critical soliton number is found as the compression boundary. An optimal-parameter diagram for compression at 1550 nm is presented.......Cascaded quadratic soliton compression in PPLN is investigated and a general critical soliton number is found as the compression boundary. An optimal-parameter diagram for compression at 1550 nm is presented....

  11. Physics at the AGS with a relativistic cascade

    Energy Technology Data Exchange (ETDEWEB)

    Kahana, S.H.; Pang, Yang; Schlagel, T.J.

    1993-02-01

    The relativistic cascade code ARC is applied to the results from heavy ion collisions, at a laboratory energy of 14.6 GeV/c per nucleon, for a variety of projectiles and targets. A detailed discussion is given of the physics and inputs of this cascade. No deviation between ARC and experiment has yet been identified as a possible signal of collective hadronic behaviour.

  12. Elastic and quasi-elastic $pp$ and $\\gamma^\\star p$ scattering in the Dipole Model

    CERN Document Server

    Flensburg, Christoffer; Lonnblad, Leif

    2008-01-01

    We have in earlier papers presented an extension of Mueller's dipole cascade model, which includes sub-leading effects from energy conservation and running coupling as well as colour suppressed saturation effects from pomeron loops via a ``dipole swing''. The model was applied to describe the total and diffractive cross sections in $pp$ and $\\gamma^*p$ collisions, and also the elastic cross section in $pp$ scattering. In this paper we extend the model to describe the corresponding quasi-elastic cross sections in $\\gamma^*p$, namely the exclusive production of vector mesons and deeply virtual compton scattering. Also for these reactions we find a good agrement with measured cross sections. In addition we obtain a reasonable description of the $t$-dependence of the elastic $pp$ and quasi-elastic $\\gamma^\\star p$ cross sections.

  13. Novel gamma cameras

    International Nuclear Information System (INIS)

    The gamma-ray cameras described are based on radiation imaging devices which permit the direct recording of the distribution of radioactive material from a radiative source, such as a human organ. They consist in principle of a collimator, a converter matrix converting gamma photons to electrons, and an electron image multiplier producing a multiplied electron output, and means for reading out the information. The electron image multiplier is a device which produces a multiplied electron image. It can be in principle, either gas avalanche electron multiplier or a multi-channel plate. The multi-channel plate employed is a novel device, described elsewhere. The three described embodiments, in which the converter matrix can be either of metal type or of scintillation crystal type, were designed and are being developed

  14. Gamma rays in thunderstorms

    International Nuclear Information System (INIS)

    Not only lightning occur in thunderstorms but also luminous flashes that are emitted upwards over the clouds. These flashes have been studied for 20 years. Satellites have detected gamma flashes with an energy of 30 MeV. It was thought that these flashes resulted from collisions between cosmic particles and cloud molecules but recent results from the Italian Agile satellite question this explanation. Gamma flashes with an energy of 100 MeV have been detected which is too high an energy to be explained by collisions with cosmic particles. Another result show the existence of very strong acceleration of electrons in areas where some type of flashes are likely to happen. (A.C.)

  15. Gamma camera system

    International Nuclear Information System (INIS)

    A detailed description is given of a novel gamma camera which is designed to produce superior images than conventional cameras used in nuclear medicine. The detector consists of a solid state detector (e.g. germanium) which is formed to have a plurality of discrete components to enable 2-dimensional position identification. Details of the electronic processing circuits are given and the problems and limitations introduced by noise are discussed in full. (U.K.)

  16. Threshold cascades with response heterogeneity in multiplex networks

    Science.gov (United States)

    Lee, Kyu-Min; Brummitt, Charles D.; Goh, K.-I.

    2014-12-01

    Threshold cascade models have been used to describe the spread of behavior in social networks and cascades of default in financial networks. In some cases, these networks may have multiple kinds of interactions, such as distinct types of social ties or distinct types of financial liabilities; furthermore, nodes may respond in different ways to influence from their neighbors of multiple types. To start to capture such settings in a stylized way, we generalize a threshold cascade model to a multiplex network in which nodes follow one of two response rules: some nodes activate when, in at least one layer, a large enough fraction of neighbors is active, while the other nodes activate when, in all layers, a large enough fraction of neighbors is active. Varying the fractions of nodes following either rule facilitates or inhibits cascades. Near the inhibition regime, global cascades appear discontinuously as the network density increases; however, the cascade grows more slowly over time. This behavior suggests a way in which various collective phenomena in the real world could appear abruptly yet slowly.

  17. Investigation of hyperfine interactions in pure silicon and NTD silicon by means of perturbed angular {gamma}-{gamma} correlation spectroscopy; Investigacao de interacoes hiperfinas em silicio puro e silicio NTD pela tecnica de correlacao angular {gamma}-{gamma} perturbada

    Energy Technology Data Exchange (ETDEWEB)

    Cordeiro, Moacir Ribeiro

    2007-07-01

    III the present work, a microscopic investigation of hyperfine interactions in single crystal silicon samples was carried out by means of Perturbed Angular {gamma} -{gamma} correlation technique (PAC), which is based in hyperfine interactions. In order to achieve these measurements, it was used {sup 111} In {yields} {sup 111}Cd radioactive probe nuclei, which decay through the well known {gamma} cascade 171-245 keV with an intermediate level of 245 keV ( I 5{sup +}/2, Q = 0.83b, T{sub 1/2} = 84.5 ns). The samples were prepared using different probe nuclei insertion methods, making possible to increase our understanding on the impact generated by each of these techniques in PAC measurements. Ion implantation, diffusion and evaporation were carefully investigated giving emphasis on its characteristics and particularities. Then, it was made a study about the concentration of intrinsic defects as function of severe annealing processes. Finally, a comparative analysis was made for all these probe nuclei insertion methods. This work also accomplished PAC measurements in single crystal silicon doped with phosphorus by means of Neutron Transmutation Doping (NTD) method, carried out in a research nuclear reactor. The extremely high doping uniformity allied to the nonexistence of previous measurements in these materials emphasize the importance of the results obtained. These results are then compared with literature results for samples doped by conventional methods presenting the respective conclusions. (author)

  18. Cascade of negative muons in atoms

    International Nuclear Information System (INIS)

    A study is made of the evolution of a negative muon captured in an atom and the formalism of energy loss associated with the muonic atom. The principal goals are to calculate reliability the muon x-ray intensities, given the initial population of the muonic orbits, to invert the problem and deduce the initial distribution from the x-ray intensities, to provide a reasonably simple and convenient tool to correlate observations, and finally, to systematize some questions of theoretical interest. The early part of the history of the muon in matter, including the atomic capture and classical phase of the atomic cascade are reviewed. In the quantal treatment of the transition rates, both radiative and electron Auger transitions are considered. In general, multipolarities up to E3 and K, L, and M electronic shells are fully investigated. Multipole radiation is treated in the conventinal way and pesents no special problems. Magnetic type transitions between states with different principal quantum numbers are shown to be small. Auger electron ejection rates are more complicated and several approximations have been adopted. The basic results have been computed in terms of elemetary functions. In the Auger transitions we have shown that magnetic multipoles can be safety neglected. The relative sizes of the rates corresponding to different multipoles are systematically studied. A comparison of results is made with atomic photoelectric effect data and with the nuclear internal conversion coefficients. A general agreement is found, except around shell thresholds. The existing data of muonic x-ray intensities in iron and thallium are analyzed in a systematic way. It is found that for Fe the initial l-distribution is almost flat, whereas that for T1 is weighted towards the high l values, sharper than statistical. As a result of the investigations and in order to make our findings usable, a computer program has been developed. 36 references

  19. Gamma-Ray Localization of Terrestrial Gamma-Ray Flashes

    CERN Document Server

    Marisaldi, M; Trois, A; Giuliani, A; Tavani, M; Labanti, C; Fuschino, F; Bulgarelli, A; Longo, F; Barbiellini, G; Del Monte, E; Moretti, E; Trifoglio, M; Costa, E; Caraveo, P; Cattaneo, P W; Chen, A; D'Ammando, F; De Paris, G; Di Cocco, G; Di Persio, G; Donnarumma, I; Evangelista, Y; Feroci, M; Ferrari, A; Fiorini, M; Froysland, T; Galli, M; Gianotti, F; Lapshov, I; Lazzarotto, F; Lipari, P; Mereghetti, S; Morselli, A; Pacciani, L; Pellizzoni, A; Perotti, F; Picozza, P; Piano, G; Pilia, M; Prest, M; Pucella, G; Rapisarda, M; Rappoldi, A; Rubini, A; Sabatini, S; Soffitta, P; Striani, E; Vallazza, E; Vercellone, S; Vittorini, V; Zambra, A; Zanello, D; Antonelli, L A; Colafrancesco, S; Cutini, S; Giommi, P; Lucarelli, F; Pittori, C; Santolamazza, P; Verrecchia, F; Salotti, L; 10.1103/PhysRevLett.105.128501

    2010-01-01

    Terrestrial Gamma-Ray Flashes (TGFs) are very short bursts of high energy photons and electrons originating in Earth's atmosphere. We present here a localization study of TGFs carried out at gamma-ray energies above 20 MeV based on an innovative event selection method. We use the AGILE satellite Silicon Tracker data that for the first time have been correlated with TGFs detected by the AGILE Mini-Calorimeter. We detect 8 TGFs with gamma-ray photons of energies above 20 MeV localized by the AGILE gamma-ray imager with an accuracy of 5-10 degrees at 50 MeV. Remarkably, all TGF-associated gamma rays are compatible with a terrestrial production site closer to the sub-satellite point than 400 km. Considering that our gamma rays reach the AGILE satellite at 540 km altitude with limited scattering or attenuation, our measurements provide the first precise direct localization of TGFs from space.

  20. Gamma heating in LMFBR media

    International Nuclear Information System (INIS)

    State-of-the-art approaches for the calculation of gamma heating in LMFBR core, blanket and reflector regions have been evaluated, with particular emphasis on coupled neutron-gamma methods/cross section sets. The major source of calculational error was found to be the apparent failure to impose a mass-energy balance on total gamma energy yield from neutron capture and other interactions in the preparation of representative neutron-gamma cross section sets. The applicability of many simplifying assumptions was demonstrated, including: volume-weighted homogenization, insensitivity to the shape of the gamma-source-spectrum, gamma energy deposition equal to gamma energy source more than 10 cm inside large zones of uniform composition, and the negligible effect of bremsstrahlung. A simple one-group method was developed to permit rapid, accurate estimation of the large (factor of 2) changes in the gamma energy deposition-to-source ratio possible near region interfaces. The approach, which also ensures conservation of mass-energy, was used in conjunction with coupled neutron-gamma computations to verify that previous experimental measurements of gamma heating in an LMFBR blanket mockup at M. I. T. were in accord with theoretical expectations within the experimental precision of +-10%

  1. Gamma heating in LMFBR media

    Energy Technology Data Exchange (ETDEWEB)

    Kalra, M.S.; Drisoll, M.J.

    1976-02-01

    State-of-the-art approaches for the calculation of gamma heating in LMFBR core, blanket and reflector regions have been evaluated, with particular emphasis on coupled neutron-gamma methods/cross section sets. The major source of calculational error was found to be the apparent failure to impose a mass-energy balance on total gamma energy yield from neutron capture and other interactions in the preparation of representative neutron-gamma cross section sets. The applicability of many simplifying assumptions was demonstrated, including: volume-weighted homogenization, insensitivity to the shape of the gamma-source-spectrum, gamma energy deposition equal to gamma energy source more than 10 cm inside large zones of uniform composition, and the negligible effect of bremsstrahlung. A simple one-group method was developed to permit rapid, accurate estimation of the large (factor of 2) changes in the gamma energy deposition-to-source ratio possible near region interfaces. The approach, which also ensures conservation of mass-energy, was used in conjunction with coupled neutron-gamma computations to verify that previous experimental measurements of gamma heating in an LMFBR blanket mockup at M. I. T. were in accord with theoretical expectations within the experimental precision of +-10%.

  2. Simulation Study on Identifiability of UHE Gamma-ray Air Showers

    Energy Technology Data Exchange (ETDEWEB)

    Wada, Y.; Inoue, N.; Miyazawa, K. [Graduate School of Science and Engineering, Saitama University, Saitama 338-8570 (Japan); Vankov, H.P. [Institute for Nuclear Research and Nuclear Energy, Bulgaria Academy, Sofia (Bulgaria)

    2008-01-15

    The chemical composition of Ultra-High-Energy (UHE) comic rays is one of unsolved mysteries, and its study will give us fruitful information on the origin and acceleration mechanism of UHE cosmic rays. Especially, a detection of UHE gamma-rays by hybrid experiments, such as AUGER and TA, will be a key to solve these questions. The characteristics of UHE gamma-ray showers have been studied by comparing the lateral and longitudinal structures of shower particles calculated with AIRES and our own simulation code, so far. There are apparent differences in a slope of lateral distribution ({eta}) and a depth of shower maximum (Xmax) between gamma-ray and proton induced showers because UHE gamma-ray showers are affected by the LPM effect and the geomagnetic cascading process in an energy region of >10{sup 19.5}eV. Different features between gamma-ray and proton showers are pointed out from the simulation study and an identifiability of gamma-ray showers from proton ones is also discussed by the method of Neural-Network-Analysis.

  3. The GAMMA-400 Space Mission

    CERN Document Server

    Cumani, P; Bonvicini, V; Topchiev, N P; Adriani, O; Aptekar, R L; Arkhangelskaja, I V; Arkhangelskiy, A I; Bergstrom, L; Berti, E; Bigongiari, G; Bobkov, S G; Boezio, M; Bogomolov, E A; Bonechi, S; Bongi, M; Bottai, S; Castellini, G; Cattaneo, P W; Dedenko, G L; De Donato, C; Dogiel, V A; Gorbunov, M S; Gusakov, Yu V; Hnatyk, B I; Kadilin, V V; Kaplin, V A; Kaplun, A A; Kheymits, M D; Korepanov, V E; Larsson, J; Leonov, A A; Loginov, V A; Longo, F; Maestro, P; Marrocchesi, P S; Menshenin, A L; Mikhailov, V V; Mocchiutti, E; Moiseev, A A; Mori, N; Moskalenko, I V; Naumov, P Yu; Papini, P; Pearce, M; Picozza, P; Popov, A V; Rappoldi, A; Ricciarini, S; Runtso, M F; Ryde, F; Serdin, O V; Sparvoli, R; Spillantini, P; Suchkov, S I; Tavani, M; Taraskin, A A; Tiberio, A; Tyurin, E M; Ulanov, M V; Vacchi, A; Vannuccini, E; Vasilyev, G I; Yurkin, Yu T; Zampa, N; Zirakashvili, V N; Zverev, V G

    2015-01-01

    GAMMA-400 is a new space mission which will be installed on board the Russian space platform Navigator. It is scheduled to be launched at the beginning of the next decade. GAMMA-400 is designed to study simultaneously gamma rays (up to 3 TeV) and cosmic rays (electrons and positrons from 1 GeV to 20 TeV, nuclei up to 10$^{15}$-10$^{16}$ eV). Being a dual-purpose mission, GAMMA-400 will be able to address some of the most impelling science topics, such as search for signatures of dark matter, cosmic-rays origin and propagation, and the nature of transients. GAMMA-400 will try to solve the unanswered questions on these topics by high-precision measurements of the Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission and the spectra of cosmic-ray electrons + positrons and nuclei, thanks to excellent energy and angular resolutions.

  4. Gamma Oscillations and Visual Binding

    Science.gov (United States)

    Robinson, Peter A.; Kim, Jong Won

    2006-03-01

    At the root of visual perception is the mechanism the brain uses to analyze features in a scene and bind related ones together. Experiments show this process is linked to oscillations of brain activity in the 30-100 Hz gamma band. Oscillations at different sites have correlation functions (CFs) that often peak at zero lag, implying simultaneous firing, even when conduction delays are large. CFs are strongest between cells stimulated by related features. Gamma oscillations are studied here by modeling mm-scale patchy interconnections in the visual cortex. Resulting predictions for gamma responses to stimuli account for numerous experimental findings, including why oscillations and zero-lag synchrony are associated, observed connections with feature preferences, the shape of the zero-lag peak, and variations of CFs with attention. Gamma waves are found to obey the Schroedinger equation, opening the possibility of cortical analogs of quantum phenomena. Gamma instabilities are tied to observations of gamma activity linked to seizures and hallucinations.

  5. gamma. -hexachlorocyclohexane (. gamma. -HCH) activates washed rabbit platelets

    Energy Technology Data Exchange (ETDEWEB)

    Lalau-Keraly, C.; Delautier, D.; Benveniste, J.; Puiseux-Dao, S.

    1986-03-01

    In guinea-pig macrophages, ..gamma..-HCH triggers activation of the phosphatidylinositol cycle and Ca/sup 2 +/ mobilization. Since these two biochemical events are also involved in platelet activation, the authors examined the effects of ..gamma..-HCH on washed rabbit platelets. Release of /sup 14/C-serotonin (/sup 14/C-5HT) and ATP from platelets prelabelled with /sup 14/C-5HT was measured simultaneously with aggregation. ..gamma..-HCH induced shape-change, aggregation and release reaction of platelets. Maximal aggregation (89 arbitrary units, AU), was observed using 170 ..mu..M ..gamma..-HCH, and was associated with 38.1 +/- 6.9% and 161 +/- 48 nM for /sup 14/C-5HT and ATP release respectively (mean +/- 1 SD, n=3). Using 80 ..mu..M ..gamma..-HCH yielded 18 AU, 12.8 +/- 1.0% and 27 +/- 14 nM for aggregation, C-5HT and ATP release respectively (n=3). No effect was observed with 40 ..mu.. M ..gamma..-HCH. Aspirin (ASA), a cyclooxygenase blocker, did not affect ..gamma..-HCH-induced platelet activation. Apyrase (APY), an ADP scavenger, inhibited by 90% aggregation induced by 170 ..mu..M ..gamma..-HCH and slightly inhibited (15%) the /sup 14/C-5HT release. In the presence of both ASA and APY, 96% inhibition of aggregation and 48% inhibition of /sup 14/C-5HT release were observed. Thus, ..gamma..-HCH induced platelet activation in a dose-dependent manner ADP, but not cyclooxygenase-dependent arachidonate metabolites, is involved in ..gamma..-HCH-induced aggregation, whereas, both appear to play a role in ..gamma..-HCH-induced release reaction.

  6. Simultaneous beta and gamma spectroscopy

    Science.gov (United States)

    Farsoni, Abdollah T.; Hamby, David M.

    2010-03-23

    A phoswich radiation detector for simultaneous spectroscopy of beta rays and gamma rays includes three scintillators with different decay time characteristics. Two of the three scintillators are used for beta detection and the third scintillator is used for gamma detection. A pulse induced by an interaction of radiation with the detector is digitally analyzed to classify the type of event as beta, gamma, or unknown. A pulse is classified as a beta event if the pulse originated from just the first scintillator alone or from just the first and the second scintillator. A pulse from just the third scintillator is recorded as gamma event. Other pulses are rejected as unknown events.

  7. Applied gamma-ray spectrometry

    CERN Document Server

    Dams, R; Crouthamel, Carl E

    1970-01-01

    Applied Gamma-Ray Spectrometry covers real life application of the gamma-ray and the devices used in their experimental studies. This book is organized into 9 chapters, and starts with discussions of the various decay processes, the possible interaction mechanisms of gamma radiation with matter, and the intrinsic and extrinsic variables, which affect the observed gamma-ray and X-ray spectra. The subsequent chapters deal with the properties and fabrication of scintillation detectors, semiconductor detectors, and proportional gas counters. These chapters present some of the most widely utilized

  8. Cascaded systems analysis of photon counting detectors

    Energy Technology Data Exchange (ETDEWEB)

    Xu, J.; Zbijewski, W.; Gang, G.; Stayman, J. W. [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Taguchi, K.; Carrino, J. A. [Russell H. Morgan Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Lundqvist, M.; Fredenberg, E. [Philips Healthcare, Solna 171 41 (Sweden); Siewerdsen, J. H., E-mail: jeff.siewerdsen@jhu.edu [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Russell H. Morgan Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21205 (United States)

    2014-10-15

    Purpose: Photon counting detectors (PCDs) are an emerging technology with applications in spectral and low-dose radiographic and tomographic imaging. This paper develops an analytical model of PCD imaging performance, including the system gain, modulation transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). Methods: A cascaded systems analysis model describing the propagation of quanta through the imaging chain was developed. The model was validated in comparison to the physical performance of a silicon-strip PCD implemented on an experimental imaging bench. The signal response, MTF, and NPS were measured and compared to theory as a function of exposure conditions (70 kVp, 1–7 mA), detector threshold, and readout mode (i.e., the option for coincidence detection). The model sheds new light on the dependence of spatial resolution, charge sharing, and additive noise effects on threshold selection and was used to investigate the factors governing PCD performance, including the fundamental advantages and limitations of PCDs in comparison to energy-integrating detectors (EIDs) in the linear regime for which pulse pileup can be ignored. Results: The detector exhibited highly linear mean signal response across the system operating range and agreed well with theoretical prediction, as did the system MTF and NPS. The DQE analyzed as a function of kilovolt (peak), exposure, detector threshold, and readout mode revealed important considerations for system optimization. The model also demonstrated the important implications of false counts from both additive electronic noise and charge sharing and highlighted the system design and operational parameters that most affect detector performance in the presence of such factors: for example, increasing the detector threshold from 0 to 100 (arbitrary units of pulse height threshold roughly equivalent to 0.5 and 6 keV energy threshold, respectively), increased the f{sub 50} (spatial

  9. Determination of the $e^+ e^- \\to \\gamma \\gamma (\\gamma)$ cross-section at LEP 2

    CERN Document Server

    Abdallah, J; Adam, W; Adzic, P; Albrecht, T; Alderweireld, T; Alemany-Fernandez, R; Allmendinger, T; Allport, P P; Amaldi, Ugo; Amapane, N; Amato, S; Anashkin, E; Andreazza, A; Andringa, S; Anjos, N; Antilogus, P; Apel, W D; Arnoud, Y; Ask, S; Åsman, B; Augustin, J E; Augustinus, A; Baillon, Paul; Ballestrero, A; Bambade, P; Barbier, R; Bardin, Dimitri Yuri; Barker, G J; Baroncelli, A; Battaglia, Marco; Baubillier, M; Becks, K H; Begalli, M; Behrmann, A; Ben-Haim, E; Benekos, N C; Benvenuti, Alberto C; Bérat, C; Berggren, M; Berntzon, L; Bertrand, D; Besançon, M; Besson, N; Bloch, D; Blom, M; Bluj, M; Bonesini, M; Boonekamp, M; Booth, P S L; Borisov, G; Botner, O; Bouquet, B; Bowcock, T J V; Boyko, I; Bracko, M; Brenner, R; Brodet, E; Brückman, P; Brunet, J M; Bugge, L; Buschmann, P; Calvi, M; Camporesi, T; Canale, V; Carena, F; Castro, N; Cavallo, F R; Chapkin, M M; Charpentier, P; Checchia, P; Chierici, R; Shlyapnikov, P; Chudoba, J; Chung, S U; Cieslik, K; Collins, P; Contri, R; Cosme, G; Cossutti, F; Costa, M J; Crennell, D J; Cuevas-Maestro, J; D'Hondt, J; Dalmau, J; Da Silva, T; Da Silva, W; Della Ricca, G; De Angelis, A; de Boer, Wim; De Clercq, C; De Lotto, B; De Maria, N; De Min, A; De Paula, L S; Di Ciaccio, L; Di Simone, A; Doroba, K; Drees, J; Dris, M; Eigen, G; Ekelöf, T J C; Ellert, M; Elsing, M; Espirito-Santo, M C; Fanourakis, G K; Fassouliotis, D; Feindt, M; Fernández, J; Ferrer, A; Ferro, F; Flagmeyer, U; Föth, H; Fokitis, E; Fulda-Quenzer, F; Fuster, J A; Gandelman, M; García, C; Gavillet, P; Gazis, E N; Gokieli, R; Golob, B; Gómez-Ceballos, G; Gonçalves, P; Graziani, E; Grosdidier, G; Grzelak, K; Guy, J; Haag, C; Hallgren, A; Hamacher, K; Hamilton, K; Haug, S; Hauler, F; Hedberg, V; Hennecke, M; Herr, H; Hoffman, J; Holmgren, S O; Holt, P J; Houlden, M A; Hultqvist, K; Jackson, J N; Jarlskog, G; Jarry, P; Jeans, D; Johansson, E K; Johansson, P D; Jonsson, P; Joram, C; Jungermann, L; Kapusta, F; Katsanevas, S; Katsoufis, E C; Kernel, G; Kersevan, B P; Kerzel, U; Kiiskinen, A P; King, B T; Kjaer, N J; Kluit, P; Kokkinias, P; Kourkoumelis, C; Kuznetsov, O; Krumshtein, Z; Kucharczyk, M; Lamsa, J; Leder, G; Ledroit, F; Leinonen, L; Leitner, R; Lemonne, J; Lepeltier, V; Lesiak, T; Liebig, W; Liko, D; Lipniacka, A; Lopes, J H; López, J M; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J; Malek, A; Maltezos, S; Mandl, F; Marco, J; Marco, R; Maréchal, B; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Martínez-Rivero, C; Masik, J; Mastroyiannopoulos, N; Matorras, F; Matteuzzi, C; Mazzucato, F; Mazzucato, M; McNulty, R; Meroni, C; Migliore, E; Mitaroff, W A; Mjörnmark, U; Moa, T; Moch, M; Mönig, K; Monge, R; Montenegro, J; Moraes, D; Moreno, S; Morettini, P; Müller, U; Münich, K; Mulders, M; Mundim, L; Murray, W; Muryn, B; Myatt, G; Myklebust, T; Nassiakou, M; Navarria, Francesco Luigi; Nawrocki, K; Nicolaidou, R; Nikolenko, M; Oblakowska-Mucha, A; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, R; Österberg, K; Ouraou, A; Oyanguren, A; Paganoni, M; Paiano, S; Palacios, J P; Palka, H; Papadopoulou, T D; Pape, L; Parkes, C; Parodi, F; Parzefall, U; Passeri, A; Passon, O; Peralta, L; Perepelitsa, V F; Perrotta, A; Petrolini, A; Piedra, J; Pieri, L; Pierre, F; Pimenta, M; Piotto, E; Podobnik, T; Poireau, V; Pol, M E; Polok, G; Pozdnyakov, V; Pukhaeva, N; Pullia, Antonio; Rames, J; Read, A; Rebecchi, P; Rehn, J; Reid, D; Reinhardt, R; Renton, P B; Richard, F; Rídky, J; Rivero, M; Rodríguez, D; Romero, A; Ronchese, P; Roudeau, P; Rovelli, T; Ruhlmann-Kleider, V; Ryabtchikov, D; Sadovskii, A; Salmi, L; Salt, J; Sander, C; Savoy-Navarro, A; Schwickerath, U; Segar, A; Sekulin, R L; Siebel, M; Sissakian, A N; Smadja, G; Smirnova, O G; Sokolov, A; Sopczak, A; Sosnowski, R; Spassoff, Tz; Stanitzki, M; Stocchi, A; Strauss, J; Stugu, B; Szczekowski, M; Szeptycka, M; Szumlak, T; Tabarelli de Fatis, T; Taffard, A C; Tegenfeldt, F; Timmermans, J; Tkatchev, L G; Tobin, M; Todorovova, S; Tomé, B; Tonazzo, A; Tortosa, P; Travnicek, P; Treille, D; Tristram, G; Trochimczuk, M; Troncon, C; Turluer, M L; Tyapkin, I A; Tyapkin, P; Tzamarias, S; Uvarov, V; Valenti, G; van Dam, P; Van Eldik, J; Van Lysebetten, A; Van Remortel, N; Van Vulpen, I; Vegni, G; Veloso, F; Venus, W A; Verdier, P; Verzi, V; Vilanova, D; Vitale, L; Vrba, V; Wahlen, H; Washbrook, A J; Weiser, C; Wicke, D; Wickens, J H; Wilkinson, G; Winter, M; Witek, M; Yushchenko, O P; Zalewska-Bak, A; Zalewski, P; Zavrtanik, D; Zhuravlov, V; Zimin, N I; Zintchenko, A; Zupan, M

    2004-01-01

    A test of the benchmark QED process e+e- -> gamma gamma (gamma) is reported, using the data collected with the DELPHI detector at LEP 2. The data analysed were recorded at centre-of-mass energies ranging from 161 GeV to 208 GeV and correspond to a total integrated luminosity of 656.4 pb^{-1}. The Born cross-section for the process e+e- -> gamma gamma (gamma) was determined, confirming the validity of QED at the highest energies ever attained in electron-positron collisions. Lower limits on the parameters of a number of possible deviations from QED, predicted within theoretical frameworks expressing physics beyond the Standard Model, were derived.

  10. Decays $h\\to \\gamma \\gamma, \\, \\gamma Z$ in the Two Higgs Doublet Model Type III

    CERN Document Server

    Cordero-Cid, A; Honorato, C G; Moretti, S

    2015-01-01

    We study the enhancement of the branching ratios of the decays $h \\to \\gamma \\gamma, \\, \\gamma Z$ in the Two Higgs Doublet Model Type III, assuming a four-zero Yukawa Texture and a general Higgs potential. We show that these processes are very sensitive to the flavor pattern of the Yukawa texture and the structure of the triple coupling $h H^\\pm H^\\mp$ from the Higgs potential. We can accomodate the parameters of the model such that one can obtain the $h \\to\\gamma \\gamma$ rates reported by the LHC and at the same time we can get a $ h \\to \\gamma Z$ fraction larger than in the SM and within experimental reach. The possibility of obtaining a light charged Higgs boson within the ensuing parameter space and compatible with current experimental measurements is also presented.

  11. Extensive air showers generated by protons, nuclei, gamma-quanta and neutrinos at energy range 1 - 100 TeV

    Science.gov (United States)

    Sinitsyna, V. G.; Arsov, T. P.; Borisov, S. S.; Musin, F. I.; Nikolsky, S. I.; Mirzafatikhov, R. M.; Kasparov, G. M.; Sinitsyna, V. Y.; Platonov, G. F.

    2003-07-01

    Basic science: nuclear physics, physics of elementary particles and connected with them astrophysics and cosmology, has studied the structure of matter on micro and macro scales. Gamma-astronomy and neutrino-astronomy, are unique experimental possibilities to search for high-energy cosmic ray sources (1012 - 1014 eV). Evidence has already been obtained of metagalactic sources exceeding by 106 - 1012 times the power of gamma-quanta galactic sources. This data puts into doubt the assumption about the galactic origin of the observed very high energy cosmic radiation. The energy spectrum of the majority of known gamma-sources with energy 1012 - 1014 eV is harder than the proton and cosmic ray nuclei spectrum. The problem of observing extensive air showers generated by neutrinos is connected with the extremely small effective cross-section of inelastic collisions of neutrinos with nuclei. However, two facts allow a search for showers generated by neutrinos. The hadron cascade with primary energy of more than 1012 eV leaves the ground to atmosphere from depth of ~ 300 g/cm2 without essential loss of total energy in the hadron cascade. The Cherenkov radiation in the atmosphere from such hadron cascades will be observed at distances from the telescope of 7.5 km over an area more than 7 . 105 m2. This partially compensates for the small cross-section of inelastic neutrino collisions. RFBR, FNP, GNTP

  12. Critical assessment and ramifications of a purported marine trophic cascade

    Science.gov (United States)

    Grubbs, R. Dean; Carlson, John K; Romine, Jason G.; Curtis, Tobey H; McElroy, W. David; McCandless, Camilla T; Cotton, Charles F; Musick, John A.

    2016-01-01

    When identifying potential trophic cascades, it is important to clearly establish the trophic linkages between predators and prey with respect to temporal abundance, demographics, distribution, and diet. In the northwest Atlantic Ocean, the depletion of large coastal sharks was thought to trigger a trophic cascade whereby predation release resulted in increased cownose ray abundance, which then caused increased predation on and subsequent collapse of commercial bivalve stocks. These claims were used to justify the development of a predator-control fishery for cownose rays, the “Save the Bay, Eat a Ray” fishery, to reduce predation on commercial bivalves. A reexamination of data suggests declines in large coastal sharks did not coincide with purported rapid increases in cownose ray abundance. Likewise, the increase in cownose ray abundance did not coincide with declines in commercial bivalves. The lack of temporal correlations coupled with published diet data suggest the purported trophic cascade is lacking the empirical linkages required of a trophic cascade. Furthermore, the life history parameters of cownose rays suggest they have low reproductive potential and their populations are incapable of rapid increases. Hypothesized trophic cascades should be closely scrutinized as spurious conclusions may negatively influence conservation and management decisions.

  13. Critical assessment and ramifications of a purported marine trophic cascade.

    Science.gov (United States)

    Grubbs, R Dean; Carlson, John K; Romine, Jason G; Curtis, Tobey H; McElroy, W David; McCandless, Camilla T; Cotton, Charles F; Musick, John A

    2016-01-01

    When identifying potential trophic cascades, it is important to clearly establish the trophic linkages between predators and prey with respect to temporal abundance, demographics, distribution, and diet. In the northwest Atlantic Ocean, the depletion of large coastal sharks was thought to trigger a trophic cascade whereby predation release resulted in increased cownose ray abundance, which then caused increased predation on and subsequent collapse of commercial bivalve stocks. These claims were used to justify the development of a predator-control fishery for cownose rays, the "Save the Bay, Eat a Ray" fishery, to reduce predation on commercial bivalves. A reexamination of data suggests declines in large coastal sharks did not coincide with purported rapid increases in cownose ray abundance. Likewise, the increase in cownose ray abundance did not coincide with declines in commercial bivalves. The lack of temporal correlations coupled with published diet data suggest the purported trophic cascade is lacking the empirical linkages required of a trophic cascade. Furthermore, the life history parameters of cownose rays suggest they have low reproductive potential and their populations are incapable of rapid increases. Hypothesized trophic cascades should be closely scrutinized as spurious conclusions may negatively influence conservation and management decisions. PMID:26876514

  14. Critical assessment and ramifications of a purported marine trophic cascade

    Science.gov (United States)

    Grubbs, R. Dean; Carlson, John K.; Romine, Jason G.; Curtis, Tobey H.; McElroy, W. David; McCandless, Camilla T.; Cotton, Charles F.; Musick, John A.

    2016-02-01

    When identifying potential trophic cascades, it is important to clearly establish the trophic linkages between predators and prey with respect to temporal abundance, demographics, distribution, and diet. In the northwest Atlantic Ocean, the depletion of large coastal sharks was thought to trigger a trophic cascade whereby predation release resulted in increased cownose ray abundance, which then caused increased predation on and subsequent collapse of commercial bivalve stocks. These claims were used to justify the development of a predator-control fishery for cownose rays, the “Save the Bay, Eat a Ray” fishery, to reduce predation on commercial bivalves. A reexamination of data suggests declines in large coastal sharks did not coincide with purported rapid increases in cownose ray abundance. Likewise, the increase in cownose ray abundance did not coincide with declines in commercial bivalves. The lack of temporal correlations coupled with published diet data suggest the purported trophic cascade is lacking the empirical linkages required of a trophic cascade. Furthermore, the life history parameters of cownose rays suggest they have low reproductive potential and their populations are incapable of rapid increases. Hypothesized trophic cascades should be closely scrutinized as spurious conclusions may negatively influence conservation and management decisions.

  15. Positional information generated by spatially distributed signaling cascades.

    Directory of Open Access Journals (Sweden)

    Javier Muñoz-García

    2009-03-01

    Full Text Available The temporal and stationary behavior of protein modification cascades has been extensively studied, yet little is known about the spatial aspects of signal propagation. We have previously shown that the spatial separation of opposing enzymes, such as a kinase and a phosphatase, creates signaling activity gradients. Here we show under what conditions signals stall in the space or robustly propagate through spatially distributed signaling cascades. Robust signal propagation results in activity gradients with long plateaus, which abruptly decay at successive spatial locations. We derive an approximate analytical solution that relates the maximal amplitude and propagation length of each activation profile with the cascade level, protein diffusivity, and the ratio of the opposing enzyme activities. The control of the spatial signal propagation appears to be very different from the control of transient temporal responses for spatially homogenous cascades. For spatially distributed cascades where activating and deactivating enzymes operate far from saturation, the ratio of the opposing enzyme activities is shown to be a key parameter controlling signal propagation. The signaling gradients characteristic for robust signal propagation exemplify a pattern formation mechanism that generates precise spatial guidance for multiple cellular processes and conveys information about the cell size to the nucleus.

  16. Trend-driven information cascades on random networks

    Science.gov (United States)

    Kobayashi, Teruyoshi

    2015-12-01

    Threshold models of global cascades have been extensively used to model real-world collective behavior, such as the contagious spread of fads and the adoption of new technologies. A common property of those cascade models is that a vanishingly small seed fraction can spread to a finite fraction of an infinitely large network through local infections. In social and economic networks, however, individuals' behavior is often influenced not only by what their direct neighbors are doing, but also by what the majority of people are doing as a trend. A trend affects individuals' behavior while individuals' behavior creates a trend. To analyze such a complex interplay between local- and global-scale phenomena, I generalize the standard threshold model by introducing a type of node called global nodes (or trend followers), whose activation probability depends on a global-scale trend, specifically the percentage of activated nodes in the population. The model shows that global nodes play a role as accelerating cascades once a trend emerges while reducing the probability of a trend emerging. Global nodes thus either facilitate or inhibit cascades, suggesting that a moderate share of trend followers may maximize the average size of cascades.

  17. TOPOLOGY AND CASCADING LINE OUTAGES IN POWER GRIDS

    Institute of Scientific and Technical Information of China (English)

    David L. PEPYNE

    2007-01-01

    Motivated by the small world network research of Watts & Strogatz, this paper studies relationships between topology and cascading line outages in electric power grids. Cascading line outages are a type of cascading collapse that can occur in power grids when the transmission network is congested. It is characterized by a self-sustaining sequence of line outages followed by grid breakup, which generally leads to widespread blackout. The main findings of this work are twofold: On one hand, the work suggests that topologies with more disorder in their interconnection topology tend to be robust with respect to cascading line outages in the sense of being able to support greater generation and demand levels than more regularly interconnected topologies. On the other hand, the work suggests that topologies with more disorder tend to be more fragile in that should a cascade get started, they tend to break apart after fewer outages than more regularly interconnected topologies. Thus, as has been observed in other complex networks, there appears to be a tradeoff between robustness and fragility.These results were established using synthetically generated power grid topologies and verified using the IEEE 57 bus and 188 bus power grid test cases.

  18. Advantages of exclusive \\gamma\\gamma production to probe high mass systems

    CERN Document Server

    Martin, A D

    2016-01-01

    We recall that the exclusive production of high mass objects via \\gamma\\gamma fusion at the LHC is not strongly suppressed in comparison with inclusive \\gamma\\gamma fusion. Therefore it may be promising to study new objects produced by the \\gamma\\gamma subprocess in experiments with exclusive kinematics. We list the main advantages of exclusive experiments.

  19. The GAMMA-400 Space Experiment: Gammas, Electrons and Nuclei Measurements

    Science.gov (United States)

    Mocchiutti, E.; Galper, A. M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Carbone, R.; Cumani, P.; Fradkin, M. I.; Gusakov, Yu. V.; Kaplin, V. A.; Kachanov, V. A.; Kheymits, M. D.; Leonov, A. A.; Longo, F.; Mazets, E. P.; Maestro, P.; Marrocchesi, P.; Mereminskiy, I. A.; Mikhailov, V. V.; Moiseev, A. A.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu.; Papini, P.; Picozza, P.; Rodin, V. G.; Runtso, M. F.; Sarkar, R.; Sparvoli, R.; Spillantini, P.; Suchkov, S. I.; Tavani, M.; Topchiev, N. P.; Vacchi, A.; Vannuccini, E.; Yurkin, Yu. T.; Zampa, N.; Zverev, V. G.; Zirakashvili, V. N.

    2013-06-01

    The present design of the new space gamma-ray telescope GAMMA-400 for the energy range 50 MeV-3 TeV is presented. The proposed instrument has an angular resolution of 1-2 degrees at E(γ)˜100 MeV and ˜0.01 degrees at E(γ)>100 GeV and an energy resolution ˜1% at E(γ)>100 GeV. By means of a deep segmented calorimeter high energy electron flux can be studied, with a proton rejection factor of about 106. The GAMMA-400 experiment is optimized to address a broad range of science topics, such as search for signatures of dark matter, studies of galactic and extragalactic gamma-ray sources, galactic and extragalactic diffuse emission, gamma-ray bursts, as well as high-precision measurements of spectra of high energy electrons, protons and nuclei up to the knee.

  20. Generalized gamma frailty model.

    Science.gov (United States)

    Balakrishnan, N; Peng, Yingwei

    2006-08-30

    In this article, we present a frailty model using the generalized gamma distribution as the frailty distribution. It is a power generalization of the popular gamma frailty model. It also includes other frailty models such as the lognormal and Weibull frailty models as special cases. The flexibility of this frailty distribution makes it possible to detect a complex frailty distribution structure which may otherwise be missed. Due to the intractable integrals in the likelihood function and its derivatives, we propose to approximate the integrals either by Monte Carlo simulation or by a quadrature method and then determine the maximum likelihood estimates of the parameters in the model. We explore the properties of the proposed frailty model and the computation method through a simulation study. The study shows that the proposed model can potentially reduce errors in the estimation, and that it provides a viable alternative for correlated data. The merits of proposed model are demonstrated in analysing the effects of sublingual nitroglycerin and oral isosorbide dinitrate on angina pectoris of coronary heart disease patients based on the data set in Danahy et al. (sustained hemodynamic and antianginal effect of high dose oral isosorbide dinitrate. Circulation 1977; 55:381-387). PMID:16220516

  1. Diffuse gamma radiation

    Science.gov (United States)

    Fichtel, C. E.; Simpson, G. A.; Thompson, D. J.

    1977-01-01

    An examination of the intensity, energy spectrum, and spatial distribution of the diffuse gamma-radiation observed by SAS-2 satellite away from the galactic plane in the energy range above 35 MeV has shown that it consists of two components. One component is generally correlated with galactic latitudes, the atomic hydrogen column density was deduced from 21 cm measurements, and the continuum radio emission, believed to be synchrotron emission. It has an energy spectrum similar to that in the plane and joins smoothly to the intense radiation from the plane. It is therefore presumed to be of galactic origin. The other component is apparently isotropic, at least on a coarse scale, and has a steep energy spectrum. No evidence is found for a cosmic ray halo surrounding the galaxy in the shape of a sphere or oblate spheroid with galactic dimensions. Constraints for a halo model with significantly larger dimensions are set on the basis of an upper limit to the gamma-ray anisotropy.

  2. The neutron-gamma Feynman variance to mean approach: gamma detection and total neutron-gamma detection (theory and practice)

    OpenAIRE

    Chernikova, Dina; Axell, Kåre; Avdic, Senada; Pázsit, Imre; Nordlund, Anders

    2014-01-01

    Two versions of the neutron-gamma variance to mean (Feynman-alpha method or Feynman-Y function) formula for either gamma detection only or total neutron-gamma detection, respectively, are derived and compared in this paper. The new formulas have a particular importance for detectors of either gamma photons or detectors sensitive to both neutron and gamma radiation. If applied to a plastic or liquid scintillation detector, the total neutron-gamma detection Feynman-Y expression corresponds to a...

  3. Gamma-Gamma Absorption in the Broad Line Region Radiation Fields of Gamma-Ray Blazars

    CERN Document Server

    Boettcher, Markus

    2016-01-01

    The expected level of gamma-gamma absorption in the Broad Line Region (BLR) radiation field of gamma-ray loud Flat Spectrum Radio Quasars (FSRQs)is evaluated as a function of the location of the gamma-ray emission region. This is done self-consistently with parameters inferred from the shape of the spectral energy distribution (SED) in a single-zone leptonic EC-BLR model scenario. We take into account all geometrical effects both in the calculation of the gamma-gamma opacity and the normalization of the BLR radiation energy density. As specific examples, we study the FSRQs 3C279 and PKS 1510-089, keeping the BLR radiation energy density at the location of the emission region fixed at the values inferred from the SED. We confirm previous findings that the optical depth due to $\\gamma\\gamma$ absorption in the BLR radiation field exceeds unity for both 3C279 and PKS 1510-089 for locations of the gamma-ray emission region inside the inner boundary of the BLR. It decreases monotonically, with distance from the cen...

  4. FERMI Observations of Gamma -Ray Emission From the Moon

    Science.gov (United States)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Atwoo, W. B.; Baldini, I.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bonamente, E.; Borgland, A. W.; Bottacini, E.; Bouvier, A.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Gehrels, N.; Hays, E.; Thompson, D. J.; McEnery, J. E.; Troja, E.

    2012-01-01

    We report on the detection of high-energy ? -ray emission from the Moon during the first 24 months of observations by the Fermi Large Area Telescope (LAT). This emission comes from particle cascades produced by cosmicray (CR) nuclei and electrons interacting with the lunar surface. The differential spectrum of the Moon is soft and can be described as a log-parabolic function with an effective cutoff at 2-3 GeV, while the average integral flux measured with the LAT from the beginning of observations in 2008 August to the end of 2010 August is F(greater than100 MeV) = (1.04 plus or minus 0.01 [statistical error] plus or minus 0.1 [systematic error]) × 10(sup -6) cm(sup -2) s(sup -1). This flux is about a factor 2-3 higher than that observed between 1991 and 1994 by the EGRET experiment on board the Compton Gamma Ray Observatory, F(greater than100 MeV)˜5×10(sup -7) cm(sup -2) s(sup -1), when solar activity was relatively high. The higher gamma -ray flux measured by Fermi is consistent with the deep solar minimum conditions during the first 24 months of the mission, which reduced effects of heliospheric modulation, and thus increased the heliospheric flux of Galactic CRs. A detailed comparison of the light curve with McMurdo Neutron Monitor rates suggests a correlation of the trends. The Moon and the Sun are so far the only known bright emitters of gamma-rays with fast celestial motion. Their paths across the sky are projected onto the Galactic center and high Galactic latitudes as well as onto other areas crowded with high-energy gamma-ray sources. Analysis of the lunar and solar emission may thus be important for studies of weak and transient sources near the ecliptic.

  5. Colliding. gamma. e and. gamma gamma. beams from single-pass e/sup +/e/sup -/ accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Ginzburg, I.F.; Kotkin, G.L.; Serbo, V.G.; Tel' nov, V.I.

    1983-08-01

    A detailed discussion is given of the main characteristics of ..gamma..e and ..gamma gamma.. collisions in the scheme previously proposed by the authors for obtaining colliding ..gamma..e and ..gamma gamma.. beams on the basis of the planned linear accelerators with e/sup +/e/sup -/ colliding beams VLEPP and SLC. It is proposed to obtain intense ..gamma.. beams with energy ..omega..approx.E/sub e/> or =50 GeV by scattering of laser light focused onto the electron beams of these accelerators. In the case when the maximum luminosity is achieved, L/sub gammae/approx.L/sub e/e or L/sub gammagamma/approx.L/sub e/e, the distribution of the luminosity in the invariant mass of the ..gamma..e or ..gamma gamma.. system is broad. Monochromatization of the collisions to a level 5--10% is possible. It involves a decrease of luminosity and is most efficient for use of electrons and laser photons with helicities of opposite sign. Examples of interesting physics problems for the proposed ..gamma..e and ..gamma gamma.. beams are given.

  6. Gamma-hadron families and scaling violation

    Science.gov (United States)

    Gaisser, T. K.; Stanev, T.; Wrotniak, J. A.

    1985-01-01

    For three different interaction models we have simulated gamma-hadron families, including the detector (Pamir emulsion chamber) response. Rates of gamma families, hadrons, and hadron-gamma ratios were compared with experiments.

  7. Cascaded Photoenhancement: Implications for Photonic Chemical and Biological Sensors

    Science.gov (United States)

    Fuller, Kirk A.; Smith, David D.

    2006-01-01

    Our analysis shows that coupling of gold nanoparticles to microspheres will evoke a cascading effect from the respective photoenhancement mechanisms. We refer to this amplification process as cascaded photoenhancement, and the resulting cavity amplification of surface-enhanced Raman scattering (SERS) and fluorescence as CASERS and CAF, respectively. Calculations, based on modal analysis of scattering and absorption by compound spheres, presented herein indicate that the absorption cross sections of metal nanoparticles immobilized onto dielectric microspheres can be greatly enhanced by cavity resonances in the microspheres without significant degradation of the resonators. Gain factors associated with CSP of 10(exp 3) - 10(exp 4) are predicted for realistic experimental conditions using homogenous microspheres. Cascaded surface photoenhancement thus has the potential of dramatically increasing the sensitivities of fluorescence and vibrational spectroscopies.

  8. Robustness of Power-law Behavior in Cascading Failure Models

    CERN Document Server

    Sloothaak, F; Zwart, A P

    2016-01-01

    Inspired by reliability issues in electric transmission networks, we use a probabilistic approach to study the occurrence of large failures in a stylized cascading failure model. In this model, lines have random capacities that initially meet the load demands imposed on the network. Every single line failure changes the load distribution in the surviving network, possibly causing further lines to become overloaded and trip as well. An initial single line failure can therefore potentially trigger massive cascading effects, and in this paper we measure the risk of such cascading events by the probability that the number of failed lines exceeds a certain large threshold. Under particular critical conditions, the exceedance probability follows a power-law distribution, implying a significant risk of severe failures. We examine the robustness of the power-law behavior by exploring under which assumptions this behavior prevails.

  9. Bearing-Only Formation Control for Cascade Multirobots

    Directory of Open Access Journals (Sweden)

    Qing Han

    2016-01-01

    Full Text Available A new formation control method is proposed, which is used to queue multirobots in a single-direction cascade structure. In the cascade formation, each robot is a follower for the previous robot and a leader for the next robot, and the robots in the middle act as both leader and follower. The follower robot can only observe the bearing information of the leader robot. The observability of the cascade leader-follower formation is studied, which shows that the bearing-only observation meets the observability conditions required for the nonlinear system. Based on the bearing-only observations, the unscented Kalman filter (UKF is employed for the state estimation of the leader and the follower robots at all levels, which enables the real-time movement control of the follower robots via the input-output feedback control. Simulation results demonstrate that the proposed approach can efficiently control the formation of multirobots as desired.

  10. A trio of dualities: walls, trees and cascades

    Energy Technology Data Exchange (ETDEWEB)

    Franco, S. [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Hanany, A. [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Institute for Advanced Study, Princeton, NJ 08540 (United States); He, Y.H. [Department of Physics and Math/Physics RG, The University of Pennsylvania, Philadelphia, PA 19104-6396 (United States)

    2004-06-01

    We study the RG flow of N=1 world-volume gauge theories of D3-brane probes on certain singular Calabi-Yau threefolds. Taking the gauge theories out of conformality by introducing fractional branes, we compute the NSVZ beta-function and follow the subsequent RG flow in the cascading manner of Klebanov-Strassler. We study the duality trees that blossom from various Seiberg dualities and encode possible cascades. We observe the appearance of duality walls, a finite limit energy scale in the UV beyond which the dualization cascade cannot proceed. Diophantine equations of the Markov type characterize the dual phases of these theories. We discuss how the classification of Markov equations for different geometries into families relates the RG flows of the corresponding gauge theories. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

  11. Cascaded VLSI Chips Help Neural Network To Learn

    Science.gov (United States)

    Duong, Tuan A.; Daud, Taher; Thakoor, Anilkumar P.

    1993-01-01

    Cascading provides 12-bit resolution needed for learning. Using conventional silicon chip fabrication technology of VLSI, fully connected architecture consisting of 32 wide-range, variable gain, sigmoidal neurons along one diagonal and 7-bit resolution, electrically programmable, synaptic 32 x 31 weight matrix implemented on neuron-synapse chip. To increase weight nominally from 7 to 13 bits, synapses on chip individually cascaded with respective synapses on another 32 x 32 matrix chip with 7-bit resolution synapses only (without neurons). Cascade correlation algorithm varies number of layers effectively connected into network; adds hidden layers one at a time during learning process in such way as to optimize overall number of neurons and complexity and configuration of network.

  12. Cascaded Parametric Amplification for Highly Efficient Terahertz Generation

    CERN Document Server

    Ravi, Koustuban; Cirmi, Giovanni; Reichert, Fabian; Schimpf, Damian N; Muecke, Oliver D; Kaertner, Franz X

    2016-01-01

    A highly efficient, practical approach to high-energy terahertz (THz) generation based on spectrally cascaded optical parametric amplification (THz-COPA) is introduced. The THz wave initially generated by difference frequency generation between a strong narrowband optical pump and optical seed (0.1-10% of pump energy) kick-starts a repeated or cascaded energy down-conversion of pump photons. This helps to greatly surpass the quantum-defect efficiency and results in exponential growth of THz energy over crystal length. In cryogenically cooled periodically poled lithium niobate, energy conversion efficiencies >8% for 100 ps pulses are predicted. The calculations account for cascading effects, absorption, dispersion and laser-induced damage. Due to the coupled nonlinear interaction of multiple triplets of waves, THz-COPA exhibits physics distinct from conventional three-wave mixing parametric amplifiers. This in turn governs optimal phase-matching conditions, evolution of optical spectra as well as limitations o...

  13. Irreversibility of the two-dimensional enstrophy cascade

    CERN Document Server

    Piretto,; Boffetta, G

    2016-01-01

    We study the time irreversibility of the direct cascade in two-dimensional turbulence by looking at the time derivative of the square vorticity along Lagrangian trajectories, a quantity which we call metenstrophy. By means of extensive numerical simulations we measure the time irreversibility from the asymmetry of the PDF of the metenstrophy and we find that it increases with the Reynolds number of the cascade, similarly to what found in three-dimensional turbulence. A detailed analysis of the different contributions to the enstrophy budget reveals a remarkable difference with respect to what observed for the direct cascade, in particular the role of the statistics of the forcing to determine the degree of irreversibility.

  14. Distributed flow optimization and cascading effects in weighted complex networks

    CERN Document Server

    Asztalos, Andrea; Szymanski, Boleslaw K; Korniss, G

    2011-01-01

    We investigate the effect of a specific edge weighting scheme $\\sim (k_i k_j)^{\\beta}$ on distributed flow efficiency and robustness to cascading failures in scale-free networks. In particular, we analyze a simple, yet fundamental distributed flow model: current flow in random resistor networks. By the tuning of control parameter $\\beta$ and by considering two general cases of relative node processing capabilities as well as the effect of bandwidth, we show the dependence of transport efficiency upon the correlations between the topology and weights. By studying the severity of cascades for different control parameter $\\beta$, we find that network resilience to cascading overloads and network throughput is optimal for the same value of $\\beta$ over the range of node capacities and available bandwidth.

  15. Spatially Organized Enzymes Drive Cofactor-Coupled Cascade Reactions.

    Science.gov (United States)

    Ngo, Tien Anh; Nakata, Eiji; Saimura, Masayuki; Morii, Takashi

    2016-03-01

    We report the construction of an artificial enzyme cascade based on the xylose metabolic pathway. Two enzymes, xylose reductase and xylitol dehydrogenase, were assembled at specific locations on DNA origami by using DNA-binding protein adaptors with systematic variations in the interenzyme distances and defined numbers of enzyme molecules. The reaction system, which localized the two enzymes in close proximity to facilitate transport of reaction intermediates, resulted in significantly higher yields of the conversion of xylose into xylulose through the intermediate xylitol with recycling of the cofactor NADH. Analysis of the initial reaction rate, regenerated amount of NADH, and simulation of the intermediates' diffusion indicated that the intermediates diffused to the second enzyme by Brownian motion. The efficiency of the cascade reaction with the bimolecular transport of xylitol and NAD(+) likely depends more on the interenzyme distance than that of the cascade reaction with unimolecular transport between two enzymes. PMID:26881296

  16. Cascading failure analysis and restoration strategy in an interdependent network

    Science.gov (United States)

    Hong, Sheng; Lv, Chuan; Zhao, Tingdi; Wang, Baoqing; Wang, Jianghui; Zhu, Juxing

    2016-05-01

    In modern society, many infrastructures are interdependent owing to functional and logical relations among components in different systems. These networked infrastructures can be modeled as interdependent networks. In the real world, different networks carry different traffic loads whose values are dynamic and stem from the load redistribution in the same network and disturbance from the interdependent network. Interdependency makes interdependent networks so fragile that even a slight initial disturbance may lead to a cascading failure of the entire systems. In this paper, interdependencies among networks are modeled and a failure cascade process is studied considering their effects on failure propagation. Meanwhile, an in-process restoration strategy after the initial failure is investigated. The restoration effects depend strongly on the trigger timing, restoration probability and priority of the restoration actions along with the additional disturbances. Our findings highlight the necessity to decrease the large-scale cascading failure by structuring and managing an interdependent network reasonably.

  17. Pair Cascades and Deathlines in Offset Magnetic Dipole Fields

    Science.gov (United States)

    Harding, Alice; Muslimov, Alex

    2010-01-01

    We investigate electron-positron pair cascades in a dipole magnetic field whose axis is offset from the neutron star center. In such a field geometry, the polar cap is displaced from the neutron star symmetry axis and the field line radius of curvature is modified. Using the modified parallel electric field near the polar cap of an offset dipole, we simulate pair cascades to determine the pair deathlines and pair multiplicities as a function of the offset parameter. We find that the pair multiplicity can change dramatically with a modest offset, with a significant increase on one side of the polar cap. Lower pair deathlines allow a larger fraction of the pulsar population, that include old and millisecond pulsars, to produce cascades with high multiplicity.

  18. Cyclic oxidation behavior of beta+gamma overlay coatings on gamma and gamma+gamma-prime alloys

    Science.gov (United States)

    Nesbitt, J. A.; Pilsner, B. H.; Carol, L. A.; Heckel, R. W.

    1984-01-01

    Detailed experimental studies of the cyclic oxidation behavior of low-pressure plasma sprayed beta+gamma coasting on gamma-phase Ni-Cr-Al alloys have shown the correlation of weight change, oxide type, and Cr and Al concentration-distance profiles as a function of oxidation time. Of special interest was the transition to breakway oxidation due to the loss of the Al flux to the oxide and the failure of the coated alloy to form an Al2O3-rich oxide scale. The experimental results on beta+gamma/gamma coating systems were used as the basis of a numerical model (ternary, semi-infinite, finite-difference analysis) which accurately predicted changes in Cr and Al concentration-distance profiles. The model was used to study parameters critical to enhancing the life of coatings which fail by a combination of Al loss in forming the oxide scale and Al loss via interdiffusion with the substrate alloy. Comparisons of beta+gamma/gamma coating behavior are made to the oxidation of coated gamma+gamma-prime substrates, both ternary Ni-Cr-Al alloys and Mar-M 247-type alloys.

  19. Airborne gamma-ray spectrometry

    DEFF Research Database (Denmark)

    Hovgaard, Jens

    A new method - Noise Adjusted Singular Value Decomposition, NASVD - for processing gamma-ray spectra has been developed as part of a Ph.D. project. By using this technique one is able to decompose a large set of data - for example from airborne gamma-ray surveys - into a few spectral components. ...

  20. Energy peak: back to the Galactic Center GeV gamma-ray excess

    CERN Document Server

    Kim, Doojin

    2015-01-01

    We propose a novel mechanism enabling us to have a continuum bump as a signature of gamma-ray excess in indirect detection experiments of dark matter (DM), postulating a generic dark sector having (at least) two DM candidates. With the assumption of non-zero mass gap between the two DM candidates, the heavier one directly communicates to the partner of the lighter one. Such a partner then decays into a lighter DM particle along with a dark "pion" or "axion-like" particle (ALP), which further decays into a pair of photons, via a more-than-one step cascade decay process. Since the cascade is initiated by the dark partner obtaining a non-trivial fixed boost factor, a continuum gamma-ray energy spectrum naturally arises. We apply the main idea to the energy spectrum of the GeV gamma-rays from around the Galactic Center (GC), and find that the relevant observational data is well-reproduced by the theory expectation predicted by the proposed mechanism. Remarkably, the relevant energy spectrum has a robust peak at h...

  1. Search for extended gamma ray emission in Markarian 421 using VERITAS observations

    CERN Document Server

    ,

    2014-01-01

    Very high energy (VHE: >100 GeV) gamma rays coming from AGN can pair-produce on the intergalactic background light generating an electromagnetic cascade. If the Intergalactic Magnetic Field (IGMF) is sufficiently strong, this cascade may result in an extended isotropic emission of photons around the source, or halo. Using VERITAS observations of the blazar Markarian 421, we search for extended emission by comparing the source angular distribution (${\\theta}^2$) from a quiescent period with one coming from a flare period, which can be considered as halo-free. ${\\chi}^2$ test showed no significant statistical differences between the samples, suggesting that the effect is either non-existent or too weak to be detected. We calculated upper limits for the extended flux considering different angle ranges, the most stringent being <8% of the Crab Nebulae flux (C.U), in the range $0\\deg \\leq {\\theta} \\leq 0.1\\deg$ .

  2. On $Z \\to \\gamma \\gamma$ decay and cancellation of axial anomaly in $Z \\to \\gamma \\gamma$ transition amplitude for massive fermions

    OpenAIRE

    Zhemchugov, E. V.

    2014-01-01

    $Z \\to \\gamma \\gamma$ decay amplitude is considered and proven to be zero due to properties of polarization vectors and Bose statistics. Triangular diagrams for a pseudoscalar $\\to \\gamma \\gamma$ and $Z \\to \\gamma \\gamma$ processes with massive fermions in the loop are explicitely calculated. In the Standard Model axial anomaly vanishes in the sum of these diagrams as Z boson is mixed with one of the Goldstone bosons.

  3. AGATA - Advanced Gamma Tracking Array

    CERN Document Server

    Akkoyun, S; Alikhani, B; Ameil, F; de Angelis, G; Arnold, L; Astier, A; Ataç, A; Aubert, Y; Aufranc, C; Austin, A; Aydin, S; Azaiez, F; Badoer, S; Balabanski, D L; Barrientos, D; Baulieu, G; Baumann, R; Bazzacco, D; Beck, F A; Beck, T; Bednarczyk, P; Bellato, M; Bentley, M A; Benzoni, G; Berthier, R; Berti, L; Beunard, R; Bianco, G Lo; Birkenbach, B; Bizzeti, P G; Bizzeti-Sona, A M; Blanc, F Le; Blasco, J M; Blasi, N; Bloor, D; Boiano, C; Borsato, M; Bortolato, D; Boston, A J; Boston, H C; Bourgault, P; Boutachkov, P; Bouty, A; Bracco, A; Brambilla, S; Brawn, I P; Brondi, A; Broussard, S; Bruyneel, B; Bucurescu, D; Burrows, I; Bürger, A; Cabaret, S; Cahan, B; Calore, E; Camera, F; Capsoni, A; Carrió, F; Casati, G; Castoldi, M; Cederwall, B; Cercus, J -L; Chambert, V; Chambit, M El; Chapman, R; Charles, L; Chavas, J; Clément, E; Cocconi, P; Coelli, S; Coleman-Smith, P J; Colombo, A; Colosimo, S; Commeaux, C; Conventi, D; Cooper, R J; Corsi, A; Cortesi, A; Costa, L; Crespi, F C L; Cresswell, J R; Cullen, D M; Curien, D; Czermak, A; Delbourg, D; Depalo, R; Descombes, T; Désesquelles, P; Detistov, P; Diarra, C; Didierjean, F; Dimmock, M R; Doan, Q T; Domingo-Pardo, C; Doncel, M; Dorangeville, F; Dosme, N; Drouen, Y; Duchêne, G; Dulny, B; Eberth, J; Edelbruck, P; Egea, J; Engert, T; Erduran, M N; Ertürk, S; Fanin, C; Fantinel, S; Farnea, E; Faul, T; Filliger, M; Filmer, F; Finck, Ch; de France, G; Gadea, A; Gast, W; Geraci, A; Gerl, J; Gernhäuser, R; Giannatiempo, A; Giaz, A; Gibelin, L; Givechev, A; Goel, N; González, V; Gottardo, A; Grave, X; Grȩbosz, J; Griffiths, R; Grint, A N; Gros, P; Guevara, L; Gulmini, M; Görgen, A; Ha, H T M; Habermann, T; Harkness, L J; Harroch, H; Hauschild, K; He, C; Hernández-Prieto, A; Hervieu, B; Hess, H; Hüyük, T; Ince, E; Isocrate, R; Jaworski, G; Johnson, A; Jolie, J; Jones, P; Jonson, B; Joshi, P; Judson, D S; Jungclaus, A; Kaci, M; Karkour, N; Karolak, M; Kaşkaş, A; Kebbiri, M; Kempley, R S; Khaplanov, A; Klupp, S; Kogimtzis, M; Kojouharov, I; Korichi, A; Korten, W; Kröll, Th; Krücken, R; Kurz, N; Ky, B Y; Labiche, M; Lafay, X; Lavergne, L; Lazarus, I H; Leboutelier, S; Lefebvre, F; Legay, E; Legeard, L; Lelli, F; Lenzi, S M; Leoni, S; Lermitage, A; Lersch, D; Leske, J; Letts, S C; Lhenoret, S; Lieder, R M; Linget, D; Ljungvall, J; Lopez-Martens, A; Lotodé, A; Lunardi, S; Maj, A; van der Marel, J; Mariette, Y; Marginean, N; Marginean, R; Maron, G; Mather, A R; Mȩczyński, W; Mendéz, V; Medina, P; Melon, B; Menegazzo, R; Mengoni, D; Merchan, E; Mihailescu, L; Michelagnoli, C; Mierzejewski, J; Milechina, L; Million, B; Mitev, K; Molini, P; Montanari, D; Moon, S; Morbiducci, F; Moro, R; Morrall, P S; Möller, O; Nannini, A; Napoli, D R; Nelson, L; Nespolo, M; Ngo, V L; Nicoletto, M; Nicolini, R; Noa, Y Le; Nolan, P J; Norman, M; Nyberg, J; Obertelli, A; Olariu, A; Orlandi, R; Oxley, D C; Özben, C; Ozille, M; Oziol, C; Pachoud, E; Palacz, M; Palin, J; Pancin, J; Parisel, C; Pariset, P; Pascovici, G; Peghin, R; Pellegri, L; Perego, A; Perrier, S; Petcu, M; Petkov, P; Petrache, C; Pierre, E; Pietralla, N; Pietri, S; Pignanelli, M; Piqueras, I; Podolyak, Z; Pouhalec, P Le; Pouthas, J; Pugnére, D; Pucknell, V F E; Pullia, A; Quintana, B; Raine, R; Rainovski, G; Ramina, L; Rampazzo, G; La Rana, G; Rebeschini, M; Recchia, F; Redon, N; Reese, M; Reiter, P; Regan, P H; Riboldi, S; Richer, M; Rigato, M; Rigby, S; Ripamonti, G; Robinson, A P; Robin, J; Roccaz, J; Ropert, J -A; Rossé, B; Alvarez, C Rossi; Rosso, D; Rubio, B; Rudolph, D; Saillant, F; Şahin, E; Salomon, F; Salsac, M -D; Salt, J; Salvato, G; Sampson, J; Sanchis, E; Santos, C; Schaffner, H; Schlarb, M; Scraggs, D P; Seddon, D; Şenyiğit, M; Sigward, M -H; Simpson, G; Simpson, J; Slee, M; Smith, J F; Sona, P; Sowicki, B; Spolaore, P; Stahl, C; Stanios, T; Stefanova, E; Stézowski, O; Strachan, J; Suliman, G; Söderström, P -A; Tain, J L; Tanguy, S; Tashenov, S; Theisen, Ch; Thornhill, J; Tomasi, F; Toniolo, N; Touzery, R; Travers, B; Triossi, A; Tripon, M; Tun-Lanoë, K M M; Turcato, M; Unsworth, C; Ur, C A; Valiente-Dobon, J J; Vandone, V; Vardaci, E; Venturelli, R; Veronese, F; Veyssiere, Ch; Viscione, E; Wadsworth, R; Walker, P M; Warr, N; Weber, C; Weisshaar, D; Wells, D; Wieland, O; Wiens, A; Wittwer, G; Wollersheim, H J; Zocca, F; Zamfir, N V; Ziȩbliński, M; Zucchiatti, A

    2011-01-01

    The Advanced GAmma Tracking Array (AGATA) is a European project to develop and operate the next generation gamma-ray spectrometer. AGATA is based on the technique of gamma-ray energy tracking in electrically segmented high-purity germanium crystals. This technique requires the accurate determination of the energy, time and position of every interaction as a gamma ray deposits its energy within the detector volume. Reconstruction of the full interaction path results in a detector with very high efficiency and excellent spectral response. The realization of gamma-ray tracking and AGATA is a result of many technical advances. These include the development of encapsulated highly-segmented germanium detectors assembled in a triple cluster detector cryostat, an electronics system with fast digital sampling and a data acquisition system to process the data at a high rate. The full characterization of the crystals was measured and compared with detector-response simulations. This enabled pulse-shape analysis algorith...

  4. Cascade Source Coding with a Side Information "Vending Machine"

    OpenAIRE

    Ahmadi, Behzad; Choudhuri, Chiranjib; Simeone, Osvaldo; Mitra, Urbashi

    2012-01-01

    The model of a side information "vending machine" (VM) accounts for scenarios in which the measurement of side information sequences can be controlled via the selection of cost-constrained actions. In this paper, the three-node cascade source coding problem is studied under the assumption that a side information VM is available and the intermediate and/or at the end node of the cascade. A single-letter characterization of the achievable trade-off among the transmission rates, the distortions ...

  5. TEMPORAL OPTICAL SOLITONS VIA MULTISTEP x(2) CASCADING

    Institute of Scientific and Technical Information of China (English)

    HUANG GUO-XIANG

    2001-01-01

    We consider a multistep X(2) cascading for light pulses with the dispersion of the system taken into account. Using the method of multiple scales we derive a set of coupled envelope equations governing the nonlinear evolution of the fundamental, second and third harmonic waves involved simultaneously in two nonlinear optical processes, i.e. second harmonic generation and sum frequency mixing. We show that three-wave temporal optical solitons are possible in three- and four-step cascading in the presence of a group-velocity mismatch between different pulses.

  6. Maximizing the Spread of Cascades Using Network Design

    CERN Document Server

    Sheldon, Daniel; Elmachtoub, Adam N; Finseth, Ryan; Sabharwal, Ashish; Conrad, Jon; Gomes, Carla P; Shmoys, David; Allen, William; Amundsen, Ole; Vaughan, William

    2012-01-01

    We introduce a new optimization framework to maximize the expected spread of cascades in networks. Our model allows a rich set of actions that directly manipulate cascade dy- namics by adding nodes or edges to the net- work. Our motivating application is one in spatial conservation planning, where a cas- cade models the dispersal of wild animals through a fragmented landscape. We propose a mixed integer programming (MIP) formu- lation that combines elements from network design and stochastic optimization. Our ap- proach results in solutions with stochastic op- timality guarantees and points to conserva- tion strategies that are fundamentally dier- ent from naive approaches.

  7. Cascade adaptive control of uncertain unified chaotic systems

    Institute of Scientific and Technical Information of China (English)

    Wei Wei; Li Dong-Hai; Wang Jing

    2011-01-01

    The chaos control of uncertain unified chaotic systems is considered. Cascade adaptive control approach with only one control input is presented to stabilize states of the uncertain unified chaotic system at the zero equilibrium point.Since an adaptive controller based on dynamic compensation mechanism is employed, the exact model of the unified chaotic system is not necessarily required.By choosing appropriate controller parameters, chaotic phenomenon can be suppressed and the response speed is tunable. Sufficient condition for the asymptotic stability of the approach is derived. Numerical simulation results confirm that the cascade adaptive control approach with only one control signal is valid in chaos control of uncertain unified chaotic systems.

  8. Cascade Control of Magnetic Levitation with Sliding Modes

    Directory of Open Access Journals (Sweden)

    Eroğlu Yakup

    2016-01-01

    Full Text Available The effectiveness and applicability of magnetic levitation systems need precise feedback control designs. A cascade control approach consisting of sliding mode control plus sliding mode control (SMC plus SMC is designed to solve position control problem and to provide a high control performance and robustness to the magnetic levitation plant. It is shown that the SMC plus SMC cascade controller is able to eliminate the effects of the inductance related uncertainties of the electromagnetic coil of the plant and achieve a robust and precise position control. Experimental and numerical results are provided to validate the effectiveness and feasibility of the method.

  9. Cascade: a high-efficiency ICF power reactor

    International Nuclear Information System (INIS)

    Cascade attains a net power-plant efficiency of 49% and its cost is competitive with high-temperature gas-cooled reactor, pressurized-water reactor, and coal-fired power plants. The Cascade reactor and blanket are made of ceramic materials and activation is 6 times less than that of the MARS Tandem Mirror Reactor operating at comparable power. Hands-on maintenance of the heat exchangers is possible one day after shutdown. Essentially all tritium is recovered in the vacuum system, with the remainder recovered from the helium power conversion loop. Tritium leakage external to the vacuum system and power conversion loop is only 0.03 Ci/d

  10. Quantifying efficient information transduction of biochemical signaling cascades

    CERN Document Server

    Tsuruyama, Tatsuaki

    2016-01-01

    Cells can be considered as systems that utilize changes in thermodynamic entropy as information. Therefore, they serve as useful models for investigating the relationships between entropy production and information transmission, i.e., signal transduction. Based on the hypothesis that cells apply a chemical reaction cascade for the most efficient transduction of information, we adopted a coding design that minimizes the number of bits per concentration of molecules that are employed for information transduction. As a result, the average rate of entropy production is uniform across all cycles in a cascade reaction. Thus, the entropy production rate can be a valuable measure for the quantification of intracellular signal transduction.

  11. Stability and Stabilization of Block-cascading Switched Linear Systems

    Institute of Scientific and Technical Information of China (English)

    Ya-Hong Zhu; Dai-Zhan Cheng

    2006-01-01

    The main purpose of this paper is to investigate the problem of quadratic stability and stabilization in switched linear systems using reducible Lie algebra. First, we investigate the structure of all real invariant subspaces for a given linear system. The result is then used to provide a comparable cascading form for switching models. Using the commoncascading form, a common quadratic Lyapunov function is (QLFs) is explored by finding common QLFs of diagonal blocks.In addition, a cascading Quaker Lemma is proved. Combining it with stability results, the problem of feedback stabilization for a class of switched linear systems is solved.

  12. Feigenbaum Cascade of Discrete Breathers in a Model of DNA

    CERN Document Server

    Maniadis, P; Bishop, A R; Rasmussen, K \\O

    2010-01-01

    We demonstrate that period-doubled discrete breathers appear from the anti-continuum limit of the driven Peyrard-Bishop-Dauxois model of DNA. These novel breathers result from a stability overlap between sub-harmonic solutions of the driven Morse oscillator. Sub-harmonic breathers exist whenever a stability overlap is present within the Feigenbaum cascade to chaos and therefore an entire cascade of such breathers exists. This phenomenon is present in any driven lattice where the on-site potential admits sub-harmonic solutions. In DNA these breathers may have ramifications for cellular gene expression.

  13. Substrate channelling as an approach to cascade reactions

    Science.gov (United States)

    Wheeldon, Ian; Minteer, Shelley D.; Banta, Scott; Barton, Scott Calabrese; Atanassov, Plamen; Sigman, Matthew

    2016-04-01

    Millions of years of evolution have produced biological systems capable of efficient one-pot multi-step catalysis. The underlying mechanisms that facilitate these reaction processes are increasingly providing inspiration in synthetic chemistry. Substrate channelling, where intermediates between enzymatic steps are not in equilibrium with the bulk solution, enables increased efficiencies and yields in reaction and diffusion processes. Here, we review different mechanisms of substrate channelling found in nature and provide an overview of the analytical methods used to quantify these effects. The incorporation of substrate channelling into synthetic cascades is a rapidly developing concept, and recent examples of the fabrication of cascades with controlled diffusion and flux of intermediates are presented.

  14. Primary defect production by high energy displacement cascades in molybdenum

    Energy Technology Data Exchange (ETDEWEB)

    Selby, Aaron P. [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Xu, Donghua, E-mail: xudh@utk.edu [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Juslin, Niklas; Capps, Nathan A. [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Wirth, Brian D. [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Oak Ridge National Laboratory, P.O. Box 2008, MS6003, Oak Ridge, TN 37831 (United States)

    2013-06-15

    We report molecular dynamics simulations of primary damage in molybdenum produced by high energy displacement cascades on the femto- to pico-second and Angstrom to nanometer scales. Clustering directly occurred for both interstitials and vacancies in the 1–50 keV cascade energy range explored. Point defect survival efficiency and partitioning probabilities into different sized clusters were quantified. The results will provide an important reference for kinetic models to describe the microstructural evolution in Mo under ion or neutron irradiations over much longer time and length scales.

  15. Rate equation modelling and investigation of quantum cascade detector characteristics

    Science.gov (United States)

    Saha, Sumit; Kumar, Jitendra

    2016-10-01

    A simple precise transport model has been proposed using rate equation approach for the characterization of a quantum cascade detector. The resonant tunneling transport is incorporated in the rate equation model through a resonant tunneling current density term. All the major scattering processes are included in the rate equation model. The effect of temperature on the quantum cascade detector characteristics has been examined considering the temperature dependent band parameters and the carrier scattering processes. Incorporation of the resonant tunneling process in the rate equation model improves the detector performance appreciably and reproduces the detector characteristics within experimental accuracy.

  16. One-dimensional hydrodynamic model generating turbulent cascade

    CERN Document Server

    Matsumoto, Takeshi

    2016-01-01

    As a minimal mathematical model generating cascade analogous to that of the Navier-Stokes turbulence in the inertial range, we propose a one-dimensional partial-differential-equation model that conserves the integral of the squared vorticity analogue (enstrophy) in the inviscid case. With a large-scale forcing and small viscosity, we find numerically that the model exhibits the enstrophy cascade, the broad energy spectrum with a sizable correction to the dimensional-analysis prediction, peculiar intermittency and self-similarity in the dynamical system structure.

  17. Aerodynamic Optimum Design of Transonic Turbine Cascades Using Genetic Algorithms

    Institute of Scientific and Technical Information of China (English)

    1997-01-01

    This paper presents an aerodynamic optimum design method for transonic turbine cascades based on the Genetic Algorithms coupled to the inviscid flow Euler Solver and the boundary-layer calculation.The Genetic Algorithms control the evolution of a population of cascades towards an optimum design.The fitness value of each string is evaluated using the flow solver.The design procedure has been developed and the behavior of the genetic algorithms has been tested.The objective functions of the design examples are the minimum mean-square deviation between the aimed pressure and computed pressure and the minimum amount of user expertise.

  18. Major disruptions, inverse cascades, and the Strauss equations

    International Nuclear Information System (INIS)

    Current-carrying plasmas in a strong dc magnetic field are subject to violent disruptions above certain thresholds. At present difficult to verify, explanations are typically sought in terms of tearing modes. An alternative explanation is in terms of inverse magnetic helicity cascades, generated from a variety of possible sources of small-scale MHD turbulence. Strongly anisotropic MHD plasmas may be described by the Strauss equations. Indications of turbulent inverse cascade behavior for the Strauss equations are sought, in parallel with earlier examples from MHD and fluid mechanics

  19. Modeling of Bit Error Rate in Cascaded 2R Regenerators

    DEFF Research Database (Denmark)

    Öhman, Filip; Mørk, Jesper

    2006-01-01

    This paper presents a simple and efficient model for estimating the bit error rate in a cascade of optical 2R-regenerators. The model includes the influences of of amplifier noise, finite extinction ratio and nonlinear reshaping. The interplay between the different signal impairments...... and the regenerating nonlinearity is investigated. It is shown that an increase in nonlinearity can compensate for an increase in noise figure or decrease in signal power. Furthermore, the influence of the improvement in signal extinction ratio along the cascade and the importance of choosing the proper threshold...

  20. Modified Smith Predictor Based Control Of Cascaded Chemical Reactor

    Directory of Open Access Journals (Sweden)

    Binu P. Mathew

    2014-04-01

    Full Text Available A cascade control with modified smith predictor is used for controlling an open loop unstable time delay process. It has three controllers, one is for servo response other two are for regulatory response. For two disturbance rejection controllers an analytical design method is used by proposing closed loop complementary sensitivity function. These two controllers are PID controller cascaded with second order lead/lag filter. Setpoint tracking controller is designed by using direct synthesis method. The main advantage of this control scheme is that the servo response can be decoupled from the regulatory response.

  1. One-dimensional hydrodynamic model generating a turbulent cascade

    Science.gov (United States)

    Matsumoto, Takeshi; Sakajo, Takashi

    2016-05-01

    As a minimal mathematical model generating cascade analogous to that of the Navier-Stokes turbulence in the inertial range, we propose a one-dimensional partial-differential-equation model that conserves the integral of the squared vorticity analog (enstrophy) in the inviscid case. With a large-scale random forcing and small viscosity, we find numerically that the model exhibits the enstrophy cascade, the broad energy spectrum with a sizable correction to the dimensional-analysis prediction, peculiar intermittency, and self-similarity in the dynamical system structure.

  2. General introduction to microstructural evolution under cascade damage conditions

    Energy Technology Data Exchange (ETDEWEB)

    Wiedersich, H.

    1993-06-01

    A short overview of the processes that affect the evolution of the microstructure during irradiation is given. The processes include defect production with an emphasis on the effects of the dynamic cascade events, defect clustering, irradiation-enhanced diffusion, radiation-induced segregation, phase decompositions and phase transformations. A simple model for the description of the development of the defect microstructure in a pure metal during cascade producing irradiation is also outlined which can provide, in principle, defect fluxes required for the description of the microstructural processes such as phase decomposition and irradiation-induced precipitation.

  3. On the trajectories of CRL...LR...R orbits, their period-doubling cascades and saddle-node bifurcation cascades

    Energy Technology Data Exchange (ETDEWEB)

    Cerrada, Lucia [Departamento de Matematica Aplicada, EUITI, Universidad Politecnica de Madrid, Ronda de Valencia 3, 28012 Madrid (Spain); ETS de Ingenieria ICAI, Universidad Pontificia Comillas de Madrid, Alberto Aguilera 25, 28015 Madrid (Spain); San Martin, Jesus, E-mail: jsm@dfmf.uned.e [Departamento de Matematica Aplicada, EUITI, Universidad Politecnica de Madrid, Ronda de Valencia 3, 28012 Madrid (Spain); Departamento de Fisica Matematica y Fluidos, UNED, Senda del Rey 9, 28040 Madrid (Spain)

    2011-04-25

    In this Letter, it is shown that from a two region partition of the phase space of a one-dimensional dynamical system, a p-region partition can be obtained for the CRL...LR...R orbits. That is, permutations associated with symbolic sequences are obtained. As a consequence, the trajectory in phase space is directly deduced from permutation. From this permutation other permutations associated with period-doubling and saddle-node bifurcation cascades are derived, as well as other composite permutations. - Research highlights: Symbolic sequences are the usual topological approach to dynamical systems. Permutations bear more physical information than symbolic sequences. Period-doubling cascade permutations associated with original sequences are obtained. Saddle-node cascade permutations associated with original sequences are obtained. Composite permutations are derived.

  4. Displacement cascades and defect annealing in tungsten, Part II: Object kinetic Monte Carlo simulation of tungsten cascade aging

    Energy Technology Data Exchange (ETDEWEB)

    Nandipati, Giridhar, E-mail: giridhar.nandipati@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA (United States); Setyawan, Wahyu; Heinisch, Howard L. [Pacific Northwest National Laboratory, Richland, WA (United States); Roche, Kenneth J. [Pacific Northwest National Laboratory, Richland, WA (United States); Department of Physics, University of Washington, Seattle, WA 98195 (United States); Kurtz, Richard J. [Pacific Northwest National Laboratory, Richland, WA (United States); Wirth, Brian D. [University of Tennessee, Knoxville, TN (United States)

    2015-07-15

    The results of object kinetic Monte Carlo (OKMC) simulations of the annealing of primary cascade damage in bulk tungsten using a comprehensive database of cascades obtained from molecular dynamics (Setyawan et al.) are described as a function of primary knock-on atom (PKA) energy at temperatures of 300, 1025 and 2050 K. An increase in SIA clustering coupled with a decrease in vacancy clustering with increasing temperature, in addition to the disparate mobilities of SIAs versus vacancies, causes an interesting effect of temperature on cascade annealing. The annealing efficiency (the ratio of the number of defects after and before annealing) exhibits an inverse U-shape curve as a function of temperature. The capabilities of the newly developed OKMC code KSOME (kinetic simulations of microstructure evolution) used to carry out these simulations are described.

  5. Displacement cascades and defect annealing in tungsten, Part II: Object kinetic Monte Carlo Simulation of Tungsten Cascade Aging

    Energy Technology Data Exchange (ETDEWEB)

    Nandipati, Giridhar; Setyawan, Wahyu; Heinisch, Howard L.; Roche, Kenneth J.; Kurtz, Richard J.; Wirth, Brian D.

    2015-07-01

    The results of object kinetic Monte Carlo (OKMC) simulations of the annealing of primary cascade damage in bulk tungsten using a comprehensive database of cascades obtained from molecular dynamics (Setyawan et al.) are described as a function of primary knock-on atom (PKA) energy at temperatures of 300, 1025 and 2050 K. An increase in SIA clustering coupled with a decrease in vacancy clustering with increasing temperature, in addition to the disparate mobilities of SIAs versus vacancies, causes an interesting effect of temperature on cascade annealing. The annealing efficiency (the ratio of the number of defects after and before annealing) exhibits an inverse U-shape curve as a function of temperature. The capabilities of the newly developed OKMC code KSOME (kinetic simulations of microstructure evolution) used to carry out these simulations are described.

  6. Sterilization by gamma irradiation

    International Nuclear Information System (INIS)

    Since 1980 the National Institute of Nuclear Research counts with an Industrial Gamma Irradiator, for the sterilization of raw materials and finished products. Through several means has been promoted the use of this technology as alternative to conventional methods of sterilization as well as steam treatment and ethylene oxide. As a result of the made promotion this irradiator has come to its saturation limit being the sterilization irradiation one of the main services that National Institute of Nuclear Research offers to producer enterprises of disposable materials of medical use also of raw materials for the elaboration of cosmetic products and pharmaceuticals as well as dehydrated foods. It is presented the trend to the sterilization service by irradiation showed by the compilation data in a survey made by potential customers. (Author)

  7. Determination of the elemental distribution in a sample using neutron induced gamma-ray emission tomography

    International Nuclear Information System (INIS)

    The factors that affect accurate, quantitative results to be obtained by neutron induced gamma-ray emission tomography are stated. The technique, which is a combination of neutron activation analysis with computerised gamma-ray emission tomography, would be enhanced by the use of multiple detector assemblies, in geometrical configurations, which simultaneously record the gamma-rays emitted and improve detection efficiency. Developments in the past few years in positron emission tomography (PET) where scanners made of single scintillation block detectors, cut into smaller segments, to form individual crystal detector elements and packed in ring around the radioactive object, are discussed. The coincident detection efficiency for annihilation photons and cascade gamma-rays for such systems are considered and the possibilities of carrying out NIGET with coincident gamma-ray tomography are explored whilst indicating some of the limitations. This is an area which requires further, intense investigation and has an impact on a wide range of applications, particularly in the biomedical field. (author)

  8. Study of X-rays and nuclear gamma -rays in muonic thallium

    CERN Document Server

    Backe, H; Jahnke, U; Kankeleit, E; Pearce, R M; Petitjean, C; Schellenberg, L; Schneuwly, H; Schröder, W U; Walter, H K; Zehnder, A

    1972-01-01

    Energies and intensities of muonic X-rays, nuclear gamma -rays and mu -capture gamma -rays were measured in natural muonic thallium with Ge (Li) detectors. The absolute intensities of higher mu X-rays were reproduced by a cascade calculation starting with a statistical population at n=20 including K-, L- and M-conversion. The electron screening effect was deduced from energies of higher mu X-rays. Eight prompt nuclear gamma -rays were found. This excitation explains the anomalous intensity ratios of the 2p-1s and 3d-2p fine structure components. From the nuclear gamma -rays of the first excited states were deduced: the magnetic h.f. splittings, muonic isomer shifts E2/M1 mixing ratios and the half-life in the presence of the muon in /sup 205/Tl. Evidence for a magnetic nuclear polarization was found. An isotope shift of Delta E=10.35+or-0.25 keV was measured for the 1s/sub 1/2/ state which is compared with data from optical spectroscopy. From an analysis of the time distribution of delayed gamma -rays from mu...

  9. Understanding Low Energy Gamma Emission from Fission and Capture with DANCE

    Science.gov (United States)

    Wilburn, Grey; Couture, Aaron; Mosby, Shea

    2012-10-01

    Los Alamos National Laboratory's Detector for Advanced Neutron Capture Experiments (DANCE) consists of 160 barium fluoride (BaF2) detectors in a 4π array used to study cross-section measurements from neutron capture reactions. Further, recent studies have taken advantage of DANCE to study the gamma emission from fission, which is not well characterized. Neutron capture is studied because of its relevance to nuclear astrophysics (almost all elements heavier than iron are formed via neutron capture) and nuclear energy, where neutron capture is a poison in the reactor. Gamma ray cascades following neutron capture and fission include photons with energies between 100 keV and 10 MeV. DANCE uses a ^6LiH sphere to attenuate scattered neutrons, the primary background in DANCE. Unfortunately, it also attenuates low energy gamma rays. In order to quantify this effect and validate simulations, direct measurements of low energy gammas were made with a high purity germanium (HPGe) crystal. HPGe's allow for high resolution measurements of low energy gamma rays that are not possible using the BaF2 crystals. The results and their agreement with simulations will be discussed.

  10. New evaluation of photon production for JEFF-3

    Science.gov (United States)

    Ravaux, S.; Bernard, D.; Santamarina, A.

    2013-03-01

    In this work, new gamma production evaluations are proposed for JEFF-3 for crucial nuclei for power reactors and Jules Horowitz Reactor: Fe, Ag, In, Cd and Gd. We specifically work on two nuclear reactions: the inelastic scattering and the radiative capture. We performed gamma production multiplicities, angular distributions and energy spectrum for incident neutron energies between 10-11 and 20 MeV by simulating the whole intranuclear gamma cascade. For this simulation, the discrete part of the nuclei level schemes came from the RIPL2.0 library and the latest EGAF measurements carried out at Budapest facility. The EGAF measurements are available in the adopted IAEA library. The continuum level scheme part has been estimated with a level density model: the Gilbert-Cameron model and a strength function model: the Generalized Lorentzian model. Then, the gamma cascade has been simulated using TALYS which is a nuclear reaction modeling code.

  11. Application of TMA (Tissue micro-array) in the observation of apoptotic cascade in postradiation damage in avian medicine

    International Nuclear Information System (INIS)

    The study of apoptotic cascade by the use of relatively new technique in avian medicine: TMA may help in early detection and prevention of acquired immunodeficiency caused by the influence of a variety of pathogenic and non-pathogenic environmental factors, which may result in severe economical losses in conditions of intensive poultry farming. There has not been any report of applying this method in veterinary medicine. Tissue micro-array (TMA) technology allows rapid visualization of molecular targets in thousands of tissue specimens at a time, either at the DNA, RNA or protein level. The technique facilitates rapid translation of molecular discoveries to clinical applications. This technology has a number of advantages compared with conventional techniques: speed and high throughput, standardization and experimental uniformity, ease of use, all histochemical and molecular detection techniques can be used, decreased assay volume, preservation of original block, and conservation of valuable tissue etc. The aim of the present work were the study of immunosuppression and apoptotic cascade and possibilities of application of tissue micro-array in chicken in experimental condition and diagnostics in avian medicine in general. The selection of samples from avian primary immune organs: thymus and Bursa Fabric was done after gamma irradiation and infectious bursal virus infection (IBDV). (authors)

  12. Planetary gamma-ray spectroscopy

    International Nuclear Information System (INIS)

    The chemical composition of a planet can be inferred from the gamma rays escaping from its surface and can be used to study its origin and evolution. The measured intensities of certain gamma rays of specific energies can be used to determine the abundances of a number of elements. The major sources of these gamma-ray lines are the decay of natural radionuclides, reactions induced by energetic galactic-cosmic-ray particles, capture of low energy neutrons, and solar-proton-induced radioactivities. The fluxes of the more intense gamma-ray lines emitted from 30 elements were calculated using current nuclear data and existing models. The source strengths for neutron-capture reactions were modified from those previously used. The fluxes emitted from a surface of average lunar composition are reported for 288 gamma-ray lines. These theoretical fluxes have been used elsewhere to convert the data from the Apollo gamma-ray spectrometers to elemental abundances and can be used with results from future missions to map the concentrations of a number of elements over a planet's surface. Detection sensitivities for these elements are examined and applications of gamma-ray spectroscopy for future orbiters to Mars and other solar-system objects are discussed

  13. Planetary gamma-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Reedy, R.C.

    1978-01-01

    The chemical composition of a planet can be inferred from the gamma rays escaping from its surface and can be used to study its origin and evolution. The measured intensities of certain gamma rays of specific energies can be used to determine the abundances of a number of elements. The major sources of these gamma-ray lines are the decay of natural radionuclides, reactions induced by energetic galactic-cosmic-ray particles, capture of low energy neutrons, and solar-proton-induced radioactivities. The fluxes of the more intense gamma-ray lines emitted from 30 elements were calculated using current nuclear data and existing models. The source strengths for neutron-capture reactions were modified from those previously used. The fluxes emitted from a surface of average lunar composition are reported for 288 gamma-ray lines. These theoretical fluxes have been used elsewhere to convert the data from the Apollo gamma-ray spectrometers to elemental abundances and can be used with results from future missions to map the concentrations of a number of elements over a planet's surface. Detection sensitivities for these elements are examined and applications of gamma-ray spectroscopy for future orbiters to Mars and other solar-system objects are discussed.

  14. Galactic plane gamma-radiation

    Science.gov (United States)

    Hartman, R. C.; Kniffen, D. A.; Thompson, D. J.; Fichtel, C. E.; Ogelman, H. B.; Tumer, T.; Ozel, M. E.

    1979-01-01

    Analysis of the SAS 2 data together with the COS B results shows that the distribution of galactic gamma-radiation has several similarities to that of other large-scale tracers of galactic structure. The radiation is primarily confined to a thin disc which exhibits offsets from b = 0 degrees similar to warping at radio frequencies. The principal distinction of the gamma-radiation is a stronger contrast in intensity between the region from 310 to 45 degrees in longitude and the regions away from the center that can be attributed to a variation in cosmic-ray density as a function of position in Galaxy. The diffuse galactic gamma-ray energy spectrum shows no significant variation in direction, and the spectrum seen along the plane is the same as that for the galactic component of the gamma-radiation at high altitudes. The uniformity of the galactic gamma-ray spectrum, the smooth decrease in intensity as a function of altitude, and the absence of any galactic gamma-ray sources at high altitudes indicate a diffuse origin for bulk of the galactic gamma-radiation rather than a collection of localized sources.

  15. CASCADIC MULTIGRID METHOD FOR THE MORTAR ELEMENT METHOD FOR P1 NONCONFORMING ELEMENT

    Institute of Scientific and Technical Information of China (English)

    Chun-jia Bi; Dan-hui Hong

    2005-01-01

    In this paper, we consider the cascadic multigrid method for the mortar P1 nonconforming element which is used to solve the Poisson equation and prove that the cascadic conjugate gradient method is accurate with optimal complexity.

  16. Whistler turbulence forward vs. inverse cascade. Three-dimensional particle-in-cell simulations

    International Nuclear Information System (INIS)

    In this study, we present the results of the first fully three-dimensional particle-in-cell simulations of decaying whistler turbulence in a magnetized, homogeneous, collisionless plasma in which both forward cascades to shorter wavelengths, and inverse cascades to longer wavelengths are allowed to proceed. For the electron beta βe = 0.10 initial value considered here, the early-time rate of inverse cascade is very much smaller than the rate of forward cascade, so that at late times the fluctuation energy in the regime of the inverse cascade is much weaker than that in the forward cascade regime. Similarly, the wavevector anisotropy in the inverse cascade regime is much weaker than that in the forward cascade regime

  17. Exciton management in organic photovoltaic multidonor energy cascades.

    Science.gov (United States)

    Griffith, Olga L; Forrest, Stephen R

    2014-05-14

    Multilayer donor regions in organic photovoltaics show improved power conversion efficiency when arranged in decreasing exciton energy order from the anode to the acceptor interface. These so-called "energy cascades" drive exciton transfer from the anode to the dissociating interface while reducing exciton quenching and allowing improved overlap with the solar spectrum. Here we investigate the relative importance of exciton transfer and blocking in a donor cascade employing diphenyltetracene (D1), rubrene (D2), and tetraphenyldibenzoperiflanthene (D3) whose optical gaps monotonically decrease from D1 to D3. In this structure, D1 blocks excitons from quenching at the anode, D2 accepts transfer of excitons from D1 and blocks excitons at the interface between D2 and D3, and D3 contributes the most to the photocurrent due to its strong absorption at visible wavelengths, while also determining the open circuit voltage. We observe singlet exciton Förster transfer from D1 to D2 to D3 consistent with cascade operation. The power conversion efficiency of the optimized cascade OPV with a C60 acceptor layer is 7.1 ± 0.4%, which is significantly higher than bilayer devices made with only the individual donors. We develop a quantitative model to identify the dominant exciton processes that govern the photocurrent generation in multilayer organic structures. PMID:24702468

  18. Vortex merging and spectral cascade in two-dimensional flows

    DEFF Research Database (Denmark)

    Nielsen, A.H.; He, X.; Juul Rasmussen, J.;

    1996-01-01

    The merging of two identical vortices is studied numerically using a spectral code. It is noted that the enstrophy cascade is most active on the distorted vortex boundaries, with a Kolmogorov-like spectrum E(k) approximate to k(-alpha), alpha less than or equal to 4, developed at high wave numbers...

  19. Crosstalk Cascades for Frame-rate Pedestrian Detection

    OpenAIRE

    Dollár, Piotr; Appel, Ron; Kienzle, Wolf

    2012-01-01

    Cascades help make sliding window object detection fast, nevertheless, computational demands remain prohibitive for numerous applications. Currently, evaluation of adjacent windows proceeds independently; this is suboptimal as detector responses at nearby locations and scales are correlated. We propose to exploit these correlations by tightly coupling detector evaluation of nearby windows. We introduce two opposing mechanisms: detector excitation of promising neighbors and inhibition of...

  20. Successful Treatment Of Homozygous Familial Hypercholesterolemia Using Cascade Filtration Plasmapheresis

    Directory of Open Access Journals (Sweden)

    Fatih Kardas

    2012-12-01

    Full Text Available OBJECTIVE: The aim of our study is to discuss the efficacy of low-density lipoprotein-cholesterol (LDL-C apheresis procedure using the cascade filtration system for pediatric patients with homozygous familial hypercholesterolemia (FH, and to clarify the adverse effects and difficulties. METHODS: LDL apheresis using the cascade filtration system was performed in 3 pediatric patients with homozygous FH. In total, 120 apheresis sessions were performed for all patients. RESULTS: Cascade filtration therapy significantly reduced the mean LDL-C values from 418 ± 62 mg/dl to 145 ± 43 mg/dl (p<0.05. We determined an acute mean reduction in the plasma levels of total cholesterol (57.9%, LDL cholesterol (70.8%, and high-density lipoprotein (HDL cholesterol (40.7%. Treatments were well tolerated. The most frequent clinical adverse effects were hypotension in 3 sessions (2.5%, chills/feeling cold (1.7% in 2 sessions, and nausea and vomiting in 3 sessions (2.5%. CONCLUSION: Our experience with three patients using the cascade filtration system were, good clinical outcomes, laboratory findings, safety of usage, minor adverse effects and technical problems.

  1. Cascaded Construction of Semi-Bent and Bent Functions

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-peng; WU Xiao-xiong; YU Xin-hua

    2009-01-01

    Based on the theory of quadratic forms over finite fields,a new construction of semi-bent and bent functions is presented.The proposed construction has a cascaded characteristic.Some previously known constructions of semi-bent and bent functions are special cases of the new construction.

  2. Calculating Node Importance Considering Cascading Failure in Traffic Networks

    Directory of Open Access Journals (Sweden)

    Zhengwu Wang

    2013-01-01

    Full Text Available The traffic network is a scale-free network. In selective attack, invalidation of few key nodes may lead to network failure so it is important to find these key nodes. In this study, the key nodes are determined by establishing calculating methods of node importance based on cascading failure behaviors. First, a cascading failure model of traffic network is posed. Its differences from current models are as follows: 1 The upper travel network and lower road network are influenced each other, 2 Capacity of nodes and links are given at first but not in direct proportion to initial flow that is related to initial capacity, 3 Travel time is used to describe status of links, 4 Capacity of links may change. The evaluation method of node importance of traffic network considering cascading failure is proposed then based on node deletion. It uses congestion status of cascading failure network to describe the node importance and algorithm procedures are designed to estimate importance of all nodes. At the end, the experiment analysis shows that network structure and traveler behaviors have in significant influence on node importance.

  3. CASCADIC MULTIGRID FOR FINITE VOLUME METHODS FOR ELLIPTIC PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    Zhong-ci Shi; Xue-jun Xu; Hong-ying Man

    2004-01-01

    In this paper, some effective cascadic multigrid methods are proposed for solving the large scale symmetric or nonsymmetric algebraic systems arising from the finite volumemethods for second order elliptic problems. Its is shown that these algorithms are optimal in both accuracy and computational complexity. Numerical expermients are repored to support out theory.

  4. Network protection against worms and cascading failures using modularity partitioning

    NARCIS (Netherlands)

    Omic, J.; Hernandez, J.M.; Van Mieghem, P.

    2010-01-01

    Communication networks are prone to virus and worms spreading and cascading failures. Recently, a number of social networking worms have spread over public Web sites. Another example is error propagation in routing tables, such as in BGP tables. The immunization and error curing applied to these sce

  5. Red-green-blue laser emission from cascaded polymer membranes

    Science.gov (United States)

    Zhai, Tianrui; Wang, Yonglu; Chen, Li; Wu, Xiaofeng; Li, Songtao; Zhang, Xinping

    2015-11-01

    Red-green-blue polymer laser emission is achieved in a free-standing membrane device consisting of three distributed feedback cavities. The polymer membrane is fabricated via interference lithography and a simple lift-off process. Multilayer structures can be assembled by cascading several polymer membranes. Thus optically pumped, simultaneous, red-green-blue laser emission is obtained from a three-layer cascaded membrane structure. This simple and low-cost fabrication technique can be used for compact, integrated laser sources.Red-green-blue polymer laser emission is achieved in a free-standing membrane device consisting of three distributed feedback cavities. The polymer membrane is fabricated via interference lithography and a simple lift-off process. Multilayer structures can be assembled by cascading several polymer membranes. Thus optically pumped, simultaneous, red-green-blue laser emission is obtained from a three-layer cascaded membrane structure. This simple and low-cost fabrication technique can be used for compact, integrated laser sources. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05965h

  6. Terahertz heterodyne spectrometer using a quantum cascade laser

    NARCIS (Netherlands)

    Ren, Y.; Hovenier, J.N.; Higgins, R.; Gao, J.R.; Klapwijk, T.M.; Shi, S.C.; Bell, A.; Klein, B.; Williams, B.S.; Kumar, S.; Hu, Q.; Reno, J.L.

    2010-01-01

    A terahertz (THz) heterodyne spectrometer is demonstrated based on a quantum cascade laser (QCL) as a local oscillator (LO) and an NbN hot electron bolometer as a mixer, and it is used to measure high-resolution molecular spectral lines of methanol (CH3OH) between 2.913–2.918 THz. The spectral lines

  7. Experimental investigation on a high subsonic compressor cascade flow

    Directory of Open Access Journals (Sweden)

    Zhang Haideng

    2015-08-01

    Full Text Available With the aim of deepening the understanding of high-speed compressor cascade flow, this paper reports an experimental study on NACA-65 K48 compressor cascade with high subsonic inlet flow. With the increase of passage pressurizing ability, endwall boundary layer behavior is deteriorated, and the transition zone is extended from suction surface to the endwall as the adverse pressure gradient increases. Cross flow from endwall to midspan, mixing of corner boundary layer and the main stream, and reversal flow on the suction surface are caused by corner separation vortex structures. Passage vortex is the main corner separation vortex. During its movement downstream, the size grows bigger while the rotating direction changes, forming a limiting circle. With higher incidence, corner separation is further deteriorated, leading to higher flow loss. Meanwhile, corner separation structure, flow mixing characteristics and flow loss distribution vary a lot with the change of incidence. Compared with low aspect-ratio model, corner separation of high aspect-ratio model moves away from the endwall and is more sufficiently developed downstream the cascade. Results obtained present details of high-speed compressor cascade flow, which is rare in the relating research fields and is beneficial to mechanism analysis, aerodynamic optimization and flow control design.

  8. A novel information cascade model in online social networks

    Science.gov (United States)

    Tong, Chao; He, Wenbo; Niu, Jianwei; Xie, Zhongyu

    2016-02-01

    The spread and diffusion of information has become one of the hot issues in today's social network analysis. To analyze the spread of online social network information and the attribute of cascade, in this paper, we discuss the spread of two kinds of users' decisions for city-wide activities, namely the "want to take part in the activity" and "be interested in the activity", based on the users' attention in "DouBan" and the data of the city-wide activities. We analyze the characteristics of the activity-decision's spread in these aspects: the scale and scope of the cascade subgraph, the structure characteristic of the cascade subgraph, the topological attribute of spread tree, and the occurrence frequency of cascade subgraph. On this basis, we propose a new information spread model. Based on the classical independent diffusion model, we introduce three mechanisms, equal probability, similarity of nodes, and popularity of nodes, which can generate and affect the spread of information. Besides, by conducting the experiments in six different kinds of network data set, we compare the effects of three mechanisms above mentioned, totally six specific factors, on the spread of information, and put forward that the node's popularity plays an important role in the information spread.

  9. Cascading Constrained 2-D Arrays using Periodic Merging Arrays

    DEFF Research Database (Denmark)

    Forchhammer, Søren; Laursen, Torben Vaarby

    2003-01-01

    We consider a method for designing 2-D constrained codes by cascading finite width arrays using predefined finite width periodic merging arrays. This provides a constructive lower bound on the capacity of the 2-D constrained code. Examples include symmetric RLL and density constrained codes....... Numerical results for the capacities are presented....

  10. Advanced dementia research in the nursing home: the CASCADE study.

    Science.gov (United States)

    Mitchell, Susan L; Kiely, Dan K; Jones, Richard N; Prigerson, Holly; Volicer, Ladislav; Teno, Joan M

    2006-01-01

    Despite the growing number of persons with advanced dementia, and the need to improve their end-of-life care, few studies have addressed this important topic. The objectives of this report are to present the methodology established in the CASCADE (Choices, Attitudes, and Strategies for Care of Advanced Dementia at the End-of-Life) study, and to describe how challenges specific to this research were met. The CASCADE study is an ongoing, federally funded, 5-year prospective cohort study of nursing [nursing home (NH)] residents with advanced dementia and their health care proxies (HCPs) initiated in February 2003. Subjects were recruited from 15 facilities around Boston. The recruitment and data collection protocols are described. The demographic features, ownership, staffing, and quality of care of participant facilities are presented and compared to NHs nationwide. To date, 189 resident/HCP dyads have been enrolled. Baseline data are presented, demonstrating the success of the protocol in recruiting and repeatedly assessing NH residents with advanced dementia and their HCPs. Factors challenging and enabling implementation of the protocol are described. The CASCADE experience establishes the feasibility of conducting rigorous, multisite dementia NH research, and the described methodology serves as a detailed reference for subsequent CASCADE publications as results from the study emerge. PMID:16917187

  11. The CASCAD system: An SGN spent fuel dry storage facility

    International Nuclear Information System (INIS)

    This paper will present SGN's dry vault spent storage system. This concept is based on the CASCAD facility, designed and built by SGN for the French Atomic Energy Commission (CEA) at Cadarache, France. Cascade has been in operation since 1990 since which time SGN has customized its storage system. Because of its extensive experience in both spent fuel assembly and dry storage of high level waste, SGN is able to design solutions fully customized to fit customers' storage requirements using proven technology. Its modular approach allows for staggered investment over a period of several years for maximum flexibility. The Cascad system meets site-specific constraints and safety requirements and is able to receive a wide range of fuels and shipping casks. Since spent fuel assemblies are stored in passive cooled pits, the system is entirely passive and therefore inherently safe. Moreover, the Cascad system allows total retrievability of spent fuel after a 50-year storage period even if the reactor building no longer exists

  12. CASCADED MULTILEVEL INVERTER BASED HARMONIC REDUCTION IN STATCOM

    Directory of Open Access Journals (Sweden)

    T. MANOKARAN,

    2010-10-01

    Full Text Available This paper deals with simulation of STATCOM used for harmonic reduction with the help of multilevel VSI circuit. Cascaded converter based multilevel inverters are used for medium to high power reactivecompensation application. Voltage unbalance is one of the main limitations of cascaded based multilevel STATCOM. A simple control strategy is proposed for the volt-age balance of a cascaded two level inverter based STATCOM. The topology consists of two conventional three phase two level inverters connected in cascade. The two inverters operate at two different dc link voltages to obtain four level operation at STATCOM out-put. Simulation studies are carried out to predict the performance of the proposed control strategy.The harmonics in STATCOM due to the voltage ripple are reduced. As a result, the size of inductor and DC capacitor can be reduced. The STATCOM has the great advantage of a fewer number of devices. The VSI is extremely fast in response to reactive power change. The simulation of the STATCOM is performed in the Simulink environment and the results are presented.

  13. Dispersive waves in fs cascaded second-harmonic generation

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Krolikowski, Wieslaw;

    2009-01-01

    Dispersive waves are observed in simulations of cascaded (phase-mismatched) second-harmonic generation. When generating ultra-short fs compressed near-IR solitons the dispersive waves are strongly red-shifted, depending on the soliton wavelength. Semi-analytical calculations predict the wavelengths....

  14. Efficient Design of Multi-stage Cascade Waveband Separator

    Institute of Scientific and Technical Information of China (English)

    Samrat Ganguly; Rauf Izmailov; Nan Tu; Ting Wang

    2003-01-01

    We propose a cascade system of filters for realizing a non-uniform waveband separation for optical networks. The use of such separation is required at the DEMUX stage in a optical OXC switching wavebands. The design of the system is based on optimized balanced tree, which minimizes the overall optical loss.

  15. Applications of cascading nonlinear optics to all-optical devices

    NARCIS (Netherlands)

    Stegeman, G.I.; Schiek, R.; Baek, Y.; Krijnen, G.J.M.; Baumann, I.; Sohler, W.

    1996-01-01

    The application of a cascaded phase shift to a fully integrated nonlinear directional coupler (NLDC) and Mach-Zehnder interferometer (MZI) is presented. It shows that for MZI, the input power was increased and the throughput was modulated between 80% and 20% of the input. For the NLDC, the switching

  16. DNA binding properties of the small cascade subunit Csa5.

    Directory of Open Access Journals (Sweden)

    Michael Daume

    Full Text Available CRISPR-Cas systems provide immunity against viral attacks in archaeal and bacterial cells. Type I systems employ a Cas protein complex termed Cascade, which utilizes small CRISPR RNAs to detect and degrade the exogenic DNA. A small sequence motif, the PAM, marks the foreign substrates. Previously, a recombinant type I-A Cascade complex from the archaeon Thermoproteus tenax was shown to target and degrade DNA in vitro, dependent on a native PAM sequence. Here, we present the biochemical analysis of the small subunit, Csa5, of this Cascade complex. T. tenax Csa5 preferentially bound ssDNA and mutants that showed decreased ssDNA-binding and reduced Cascade-mediated DNA cleavage were identified. Csa5 oligomerization prevented DNA binding. Specific recognition of the PAM sequence was not observed. Phylogenetic analyses identified Csa5 as a universal member of type I-A systems and revealed three distinct groups. A potential role of Csa5 in R-loop stabilization is discussed.

  17. Impedance Interaction Modeling and Analysis for Bidirectional Cascaded Converters

    DEFF Research Database (Denmark)

    Tian, Yanjun; Deng, Fujin; Chen, Zhe;

    2015-01-01

    For the cascaded converter system, the output impedance of source converter interacts with the input impedance of load converter, and the interaction may cause the system instability. In bidirectional applications, when the power flow is reversed, the impedance interaction also varies, which brin...

  18. Pulsar wind model of close massive gamma-ray binaries: The influence of geometry in the pulsar wind zone processes

    CERN Document Server

    Sierpowska-Bartosik, Agnieszka

    2008-01-01

    Several gamma-ray binaries have been recently detected by the High-Energy Stereoscopy Array (H.E.S.S.) and the Major Atmospheric Imaging Cerenkov (MAGIC) telescope. In at least two cases, their nature is unknown, since a distinctive, final observational feature for a black hole or a pulsar compact object companion is still missing. In this paper we aim to provide the details of a theoretical model of close gamma-ray binaries containing a young energetic pulsar as compact object. This model includes a detailed account of the system geometry, the angular dependence of processes such as Klein-Nishina inverse Compton and gamma-gamma absorption, and a Monte Carlo simulation of cascading. We present and derive the used formulae and give all details about their numerical implementation, particularly, on the computation of cascades. In this model, emphasis is put in the processes occurring in the pulsar wind zone of the binary, i.e., the region between the pulsar and the shock in between of the two stars, since as we...

  19. $\\gamma\\gamma$ physics with the KLOE experiment

    CERN Document Server

    Archilli, F; Badoni, D; Balwierz, I; Bencivenni, G; Bini, C; Bloise, C; Bocci, V; Bossi, F; Branchini, P; Budano, A; Bulychjev, S A; Campana, P; Capon, G; Ceradini, F; Ciambrone, P; Czerwinski, E; Dane, E; De Lucia, E; De Robertis, G; De Santis, A; De Zorzi, G; Di Domenico, A; Di Donato, C; Domenici, D; Erriquez, O; Fanizzi, G; Felici, G; Fiore, S; Franzini, P; Gauzzi, P; Giovannella, S; Gonnella, F; Graziani, E; Happacher, F; Hoistad, B; Iarocci, E; Jacewicz, M; Johansson, T; Kulikov, V; Kupsc, A; Lee-Franzini, J; Loddo, F; Martemianov, M; Martini, M; Matsyuk, M; Messi, R; Miscetti, S; Morello, G; Moricciani, D; Moskal, P; Nguyen, F; Passeri, A; Patera, V; Longhi, I Prado; Ranieri, A; Santangelo, P; Sarra, I; Schioppa, M; Sciascia, B; Sciubba, A; Silarski, M; Taccini, C; Tortora, L; Venanzoni, G; Versaci, R; Wislicki, W; Wolke, M; Zdebik, J

    2011-01-01

    The processes $e^+e^-\\to e^+e^-X$, with $X$ being either the $\\eta$ meson or $\\pi^0\\pi^0$, are studied at DA$\\Phi$NE, with $e^+e^-$ beams colliding at $\\sqrt{s}\\simeq1$ GeV, below the $\\phi$ resonance peak. The data sample is from an integrated luminosity of 240 pb$^{-1}$, collected by the KLOE experiment without tagging of the outgoing $e^+e^-$. Preliminary results are presented on the observation of the $\\gamma\\gamma\\to\\eta$ process, with both $\\eta\\to\\pi^+\\pi^-\\pi^0$ and $\\eta\\to\\pi^0\\pi^0\\pi^0$ channels, and the evidence for $\\gamma\\gamma\\to\\pi^0\\pi^0$ production at low $\\pi^0\\pi^0$ invariant mass.

  20. Total Cross Section in $\\gamma\\gamma$ Collisions at LEP

    CERN Document Server

    Acciarri, M; Adriani, O; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Ambrosi, G; Anderhub, H; Andreev, V P; Angelescu, T; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, L; Balandras, A; Baldew, S V; Todorova-Nová, S; Banerjee, Sw; Barczyk, A; Barillère, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Bhattacharya, S; Biasini, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brochu, F; Buffini, A; Buijs, A; Burger, J D; Burger, W J; Cai, X D; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Castellini, G; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Cesaroni, F; Chamizo-Llatas, M; Chang, Y H; Chaturvedi, U K; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Civinini, C; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; Cotorobai, F; de la Cruz, B; Csilling, Akos; Cucciarelli, S; Dai, T S; van Dalen, J A; D'Alessandro, R; De Asmundis, R; Déglon, P L; Degré, A; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Van Dierendonck, D N; Dionisi, C; Dittmar, Michael; Dominguez, A; Doria, A; Dova, M T; Duchesneau, D; Dufournaud, D; Duinker, P; El-Mamouni, H; Engler, A; Eppling, F J; Erné, F C; Ewers, A; Extermann, Pierre; Fabre, M; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, Marta; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gau, S S; Gentile, S; Gheordanescu, N; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hasan, A; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hidas, P; Hirschfelder, J; Hofer, H; Holzner, G; Hoorani, H; Hou, S R; Hu, Y; Iashvili, I; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Khan, R A; Käfer, D; Kaur, M; Kienzle-Focacci, M N; Kim, D; Kim, J K; Kirkby, Jasper; Kiss, D; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Kopp, A; Koutsenko, V F; Kräber, M H; Krämer, R W; Krenz, W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Lee, H J; Le Goff, J M; Leiste, R; Levchenko, P M; Li Chuan; Likhoded, S A; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Lübelsmeyer, K; Luci, C; Luckey, D; Lugnier, L; Luminari, L; Lustermann, W; Ma Wen Gan; Maity, M; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Mans, J; Marian, G; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Von der Mey, M; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Moulik, T; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nisati, A; Nowak, H; Ofierzynski, R A; Organtini, G; Oulianov, A; Palomares, C; Pandoulas, D; Paoletti, S; Paolucci, P; Paramatti, R; Park, H K; Park, I H; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pieri, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Postema, H; Pothier, J; Prokofiev, D O; Prokofev, D; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Raven, G; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Rodin, J; Roe, B P; Romero, L; Rosca, A; Rosier-Lees, S; Roth, S; Rosenbleck, C; Roux, B; Rubio, Juan Antonio; Ruggiero, G; Rykaczewski, H; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Sanders, M P; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schopper, Herwig Franz; Schotanus, D J; Schwering, G; Sciacca, C; Seganti, A; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Smith, B; Spillantini, P; Steuer, M; Stickland, D P; Stone, A; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S V; Suter, H; Swain, J D; Szillási, Z; Sztaricskai, T; Tang, X W; Tauscher, Ludwig; Taylor, L; Tellili, B; Teyssier, D; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Uchida, Y; Ulbricht, J; Valente, E; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Vorvolakos, A; Wadhwa, M

    2001-01-01

    The reaction e+e- -> e+e- gamma* gamma* -> e+e- hadrons for quasi-real photons is studied using data from root(s) = 183 GeV up to 202 GeV. Results on the total cross sections sigma(e+e- -> e+e- hadrons) and sigma(+e- gamma* gamma* -> e+e- hadrons) are given for the two-photon centre-of-mass energies 5 GeV < Wgammagamma < 185 GeV. The total cross section of two real photons is described by a Regge parametrisation. We observe a steeper rise with the two-photon centre-of-mass energy as compared to the hadron-hadron and the photon-proton cross sections. The data are also compared to the expectations of different theoretical models.

  1. Gamma-ray Pulsar Revolution

    OpenAIRE

    Caraveo, Patrizia A.

    2013-01-01

    Isolated Neutron Stars (INSs) were the first sources identified in the field of high-energy gamma-ray astronomy. At first, in the 70s, there were only two identified sources, the Crab and Vela pulsars. However, although few in number, these objects were crucial in establishing the very concept of a gamma-ray source. Moreover, they opened up significant discovery space both in the theoretical and phenomenological fronts. The need to explain the copious gamma-ray emission of these pulsars led t...

  2. Bonds futures: Delta? No gamma!

    OpenAIRE

    Henrard, Marc

    2006-01-01

    Bond futures are liquid but complex instruments. Here they are analysed in a one-factor Gaussian HJM model. The in-the-model delta and out-of-the-model delta and gamma are studied. An explicit formula is provided for in-the-model delta. The out-of-the-model delta and gamma are equivalent to partial derivatives with respect to discount factors. In particular cases the derivative can not be obtained by standard techniques. The same situations lead to cases where the gammas (second order partial...

  3. Gamma radiation from radio pulsars

    Science.gov (United States)

    Ruderman, Malvin

    1990-01-01

    The probable magnetospheric location and source of the gamma ray emission from some young radiopulsars is discussed. The suggested evolution of this emission as a function of pulsar period gives a diminished gamma-ray luminosity for a more rapidly spinning pre-Crab pulsar. A greatly enhanced one, similar to that of unidentified Cos B sources, is predicted for a slightly slower post-Vela pulsar, followed by a relatively rapid quenching of the gamma-ray luminosity at still longer periods. Possible anomalous exo-magnetospheric pulsed MeV and TeV-PeV radiation from the Crab pulsar is considered.

  4. Numerical integration of electromagnetic cascade equations, discussion of results for air, copper, iron, and lead

    International Nuclear Information System (INIS)

    The longitudinal development of electromagnetic cascades in air, copper, iron, and lead is studied on the basis of results derived recently by numerical integration of the cascade equations applying rather accurate expressions for the cross-sections involved with the interactions of high energy electrons, positrons, and photons in electromagnetic cascades. Special attention is given to scaling properties of transition curves. It is demonstrated that a good scaling may be achieved by means of the depth of maximum cascade development. (author)

  5. Diamond gamma dose rate monitor; Debitmetre gamma en diamant

    Energy Technology Data Exchange (ETDEWEB)

    Brambilla, A.; Chambaud, P.; Tromson, D.; Bergonzo, P.; Foulon, F.; Joffre, F. [CEA Saclay, Dept. d' Electronique et d' Instrumentation Nucleaire, LETI, 91 - Gif-sur-Yvette (France)

    1999-07-01

    CVD (chemical vapor deposition) diamond detectors for X and gamma dose rate monitoring have been fabricated and tested in the 1 mGy/h to 1 kGy/h range. They show excellent performances in terms of sensitivity and linearity. Radiation hardness measurement under 60-Co gamma rays have demonstrated long term stability for integrated doses up to 500 kGy. (authors)

  6. Hydrothermal heat discharge in the Cascade Range, northwestern United States

    Science.gov (United States)

    Ingebritsen, S.E.; Mariner, R.H.

    2010-01-01

    Hydrothermal heat discharge in the Cascade Range includes the heat discharged by thermal springs, by "slightly thermal" springs that are only a few degrees warmer than ambient temperature, and by fumaroles. Thermal-spring heat discharge is calculated on the basis of chloride-flux measurements and geothermometer temperatures and totals ~ 240 MW in the U.S. part of the Cascade Range, excluding the transient post-1980 discharge at Mount St. Helens (~80 MW as of 2004-5). Heat discharge from "slightly thermal" springs is based on the degree of geothermal warming (after correction for gravitational potential energy effects) and totals ~. 660. MW. Fumarolic heat discharge is calculated by a variety of indirect and direct methods and totals ~160 MW, excluding the transient mid-1970s discharge at Mount Baker (~80 MW) and transient post-1980 discharge at Mount St. Helens (>. 230. MW as of 2005). Other than the pronounced transients at Mount St. Helens and Mount Baker, hydrothermal heat discharge in the Cascade Range appears to be fairly steady over a ~25-year period of measurement. Of the total of ~. 1050. MW of "steady" hydrothermal heat discharge identified in the U.S. part of the Cascade Range, less than 50. MW occurs north of latitude 45??15' N (~0.1 MW per km arc length from 45??15' to 49??N). Much greater rates of hydrothermal heat discharge south of 45??15'N (~1.7 MW per km arc length from 40?? to 45??15'N) may reflect the influence of Basin and Range-style extensional tectonics (faulting) that impinges on the Cascades as far north as Mount Jefferson but is not evident farther north. ?? 2010.

  7. Constraints on The Hadronic Content of Gamma Ray Bursts

    CERN Document Server

    Yacobi, Lee; Behar, Ehud

    2014-01-01

    The IceCube high-energy neutrino telescope has been collecting data since 2006. Conversely, hundreds of Gamma Ray Bursts (GRBs) have been detected by the GBM on board Fermi, since its launch in 2008. So far no neutrino event has been associated with a GRB, despite many models predicting the generation of high energy neutrinos through GRB photon interaction with PeV protons in the GRB jet. We use the non-detection of neutrinos to constrain the hadronic content of GRB jets independent of jet model parameters. Assuming a generic particle spectrum of $E^{-\\alpha}$ with $\\alpha = 2$, we find that the ratio of the energy carried by pions to that in electrons has to be small $f_\\pi / f_e \\lesssim 0.24$ at 95\\% confidence level. A distribution of spectral slopes can lower $f_\\pi / f_e$ by orders of magnitude. Another limit, independent of neutrinos, is obtained if one ascribes the measured Fermi/LAT GeV gamma-ray emission to pair-photon cascades of high-energy photons resulting from (the same photon-hadronic interact...

  8. Low energy proton capture study of the 14N(p, gamma)15O reaction

    Science.gov (United States)

    Daigle, Stephen Michael

    The 14N(p,gamma)15O reaction regulates the rate of energy production for stars slightly more massive than the sun throughout stable hydrogen burning on the main sequence. The 14N(p,gamma)15O reaction rate also determines the luminosity for all stars after leaving the main sequence when their cores have exhausted hydrogen fuel, and later when they become red giant stars. The significant role that this reaction plays in stellar evolution has far-reaching consequences, from neutrino production in our Sun, to age estimates of globular clusters in our Galaxy. The weak cross section and inherent coincidence summing in the 15O gamma-ray decay scheme make a precision measurement of the astrophysical S-factor especially challenging, particularly for the ground-state transition. The present study, performed in the Laboratory for Experimental Nuclear Astrophysics (LENA), was aimed at measuring the ground-state transition at low energy by utilizing a new 24-element, position-sensitive, NaI(Tl) detector array. Because the array is highly segmented, the 14N( p,gamma)15O S-factor was evaluated for transitions to the ground, 5.18, 6.18, and 6.79 MeV states without the need for coincidence summing corrections. Additionally, the position-sensitivity of the detector was exploited to measure the angular correlation of the two-photon cascades. Software cuts were made to the data in order to identify single and coincident gamma-ray events and a fraction fit analysis technique was used to extract the characteristic 15O peaks from the composite gamma-ray spectrum. The results from the current work demonstrated a new approach to measuring weak nuclear cross sections near astrophysically relevant energies that, with refinements, has broader applications in gamma-ray spectroscopy.

  9. Asymmetric function of theta and gamma activity in syllable processing: an intra-cortical study

    Directory of Open Access Journals (Sweden)

    Benjamin eMorillon

    2012-07-01

    Full Text Available Low-gamma (25-45 Hz and theta (4-8 Hz oscillations are proposed to underpin the integration of phonemic and syllabic information, respectively. How these two scales of analysis split functions across hemispheres is unclear. We analyzed cortical responses from an epileptic patient with a rare bilateral electrode implantation (stereotactic EEG in primary (A1/BA41 and A2/BA42 and association auditory cortices (BA22. Using time-frequency analyses, we confirmed the dominance of a 5-6 Hz theta activity in right and of a low-gamma (25-45 Hz activity in left primary auditory cortices (A1/A2, during both resting state and syllable processing. We further detected high-theta (7-8 Hz resting activity in left primary, but also associative auditory regions. In left BA22, its phase correlated with high-gamma induced power. Such a hierarchical relationship across theta and gamma frequency bands (theta/gamma phase-amplitude coupling could index the process by which the neural code shifts from stimulus feature- to phonological- encoding, and is associated with the transition from evoked to induced power responses. These data suggest that theta and gamma activity in right and left auditory cortices bear different functions. They support a scheme where slow parsing of the acoustic information dominates in right-hemisphere at a syllabic (5-6 Hz rate, and left auditory cortex exhibits a more complex cascade of oscillations, reflecting the possible extraction of transient acoustic cues at a fast (~25-45 Hz rate, subsequently integrated at a slower, e.g. syllabic one. Slow oscillations could functionally participate to speech processing by structuring gamma activity in left BA22, where abstract percepts emerge.

  10. Status of development of the Gamma Ray Energy Tracking Array (GRETA)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, I.Y.; Schmid, G.J.; Vetter, K. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1996-12-31

    The current generation of large gamma-ray detector arrays, Gammasphere, Eurogam and GASP, are based on modules of Compton suppressed Ge detectors. Due to the solid angle occupied by the Compton shields and to gamma rays escaping the detector, the total peak efficiency of such a design is limited to about 20% for a 1.3 MeV gamma ray. A shell consisting of closely packed Ge detectors has been suggested as the solution to the efficiency limitation. In this case, the entire solid angle is covered by Ge detectors, and by adding the signal from neighboring detectors, the escaped energy is recovered and much higher efficiency can be achieved (e.g. 60% for a 1.3 MeV gamma ray). However, for high multiplicity cascades, the summing of two gamma rays hitting neighboring detectors reduces the efficiency and increases the background. In order to reduce this summing, a large number of detectors is required. For example, with a multiplicity of 25, one needs about 1500 detectors to keep the probability of false summing below 10% and the cost of such a detector array will be prohibitive. Rather than such an approach, the authors are developing a new concept for a gamma-ray array; a shell of closely-packed Ge detectors consisting of 100-200 highly-segmented elements. The high granularity of the segmented Ge detector enables the authors to resolve each of the scattering interactions and determine its position and energy. A tracking algorithm, using the position and energy information, will then identify the interactions belonging to a particular gamma ray and its energy is obtained by summing only these interactions. Such an array can reach a total efficiency about 60%, with a resolving power 1000 times higher than that of current arrays.

  11. Interband cascade light emitting devices based on type-II quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui Q.; Lin, C.H.; Murry, S.J. [Univ. of Houston, TX (United States). Space Vacuum Epitaxy Center] [and others

    1997-06-01

    The authors discuss physical processes in the newly developed type-II interband cascade light emitting devices, and review their recent progress in the demonstration of the first type-II interband cascade lasers and the observation of interband cascade electroluminescence up to room temperature in a broad mid-infrared wavelength region (extended to 9 {mu}m).

  12. 77 FR 73651 - Cascade Energy Storage, LLC; Notice of Preliminary Permit Application Accepted for Filing and...

    Science.gov (United States)

    2012-12-11

    ... Federal Energy Regulatory Commission Cascade Energy Storage, LLC; Notice of Preliminary Permit Application..., 2012, Cascade Energy Storage, LLC, filed an application for a preliminary permit, pursuant to section 4.... Matthew Shapiro, Chief Executive Officer, Cascade Energy Storage, LLC, 1210 W. Franklin Street, Ste....

  13. Prediction and Control of Network Cascade: Example of Power Grid or Networking Adaptability from WMD Disruption and Cascading Failures

    Energy Technology Data Exchange (ETDEWEB)

    Chertkov, Michael [Los Alamos National Laboratory

    2012-07-24

    The goal of the DTRA project is to develop a mathematical framework that will provide the fundamental understanding of network survivability, algorithms for detecting/inferring pre-cursors of abnormal network behaviors, and methods for network adaptability and self-healing from cascading failures.

  14. DECREASING OF WATER TROPHY IN CASCADE SYSTEMS, ON EXAMPLE OF THE SOŁA RIVER DAM CASCADE (SOUTHERN POLAND

    Directory of Open Access Journals (Sweden)

    Ewa Jachniak

    2014-10-01

    Full Text Available In this thesis the subject of water self-purification in cascade systems of water reservoirs was engaged. The results of hydrobiological research of three dam reservoirs (Tresna, Porąbka and Czaniec, creating the Soła river dam cascade were presented. The trophic status of these reservoirs was defined on the grounds of the concentration of chlorophyll a, biomass of phytoplankton and occurrence of indicating species of planktonic algae. The results of research indicated on decreasing of water trophy in the layout from the highest into the lowest reservoir of the cascade. The average concentrations of chlorophyll a amounted appropriately 19,99 μg·dm-3, 8,74 μg·dm-3 and 4,29 μg·dm-3, instead the average biomass of phytoplankton amounted appropriately 4,1 mg·dm-3, 3,4 mg·dm-3 and 0,1 mg·dm-3. The observed species of algae confirmed occurrence of differences between reservoirs. In Tresna reservoir more species of phytoplankton indicating for eutrophy were thrived, instead in Porąbka and Czaniec reservoirs the species occurring in oligomesotrophic water thrived. Water self-purification in the Soła river dam cascade expressed decreasing of their fertility is important for water management of the region, because the Czaniec reservoir fulfill a function of water-supply reservoir.

  15. Search for an extended VHE gamma-ray emission from Mrk 421 and Mrk 501 with the MAGIC Telescope

    CERN Document Server

    Aleksić, J; Antoranz, P; Backes, M; Baixeras, C; Barrio, J A; Bastieri, D; González, J Becerra; Bednarek, W; Berdyugin, A; Berger, K; Bernardini, E; Biland, A; Blanch, O; Bock, R K; Bonnoli, G; Bordas, P; Tridon, D Borla; Bosch-Ramon, V; Bose, D; Braun, I; Bretz, T; Britzger, D; Camara, M; Carmona, E; Carosi, A; Colin, P; Commichau, S; Contreras, J L; Cortina, J; Costado, M T; Covino, S; Dazzi, F; De Angelis, A; del Pozo, E De Cea; Reyes, R De los; De Lotto, B; De Maria, M; De Sabata, F; Mendez, C Delgado; Doert, M; Domínguez, A; Prester, D Dominis; Dorner, D; Doro, M; Elsaesser, D; Errando, M; Ferenc, D; Fonseca, M V; Font, L; López, R J García; Garczarczyk, M; Gaug, M; Godinovic, N; Hadasch, D; Herrero, A; Hildebrand, D; Höhne-Mönch, D; Hose, J; Hrupec, D; Hsu, C C; Jogler, T; Klepser, S; Krähenbühl, T; Kranich, D; La Barbera, A; Laille, A; Leonardo, E; Lindfors, E; Lombardi, S; Longo, F; López, M; Lorenz, E; Majumdar, P; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Mariotti, M; Martínez, M; Mazin, D; Meucci, M; Miranda, J M; Mirzoyan, R; Miyamoto, H; Moldón, J; Moles, M; Moralejo, A; Nieto, D; Nilsson, K; Ninkovic, J; Orito, R; Oya, I; Paiano, S; Paoletti, R; Paredes, J M; Partini, S; Pasanen, M; Pascoli, D; Pauss, F; Pegna, R G; Perez-Torres, M A; Persic, M; Peruzzo, L; Prada, F; Prandini, E; Puchades, N; Puljak, I; Reichardt, I; Rhode, W; Ribó, M; Rico, J; Rissi, M; Rügamer, S; Saggion, A; Saito, T Y; Salvati, M; Sánchez-Conde, M; Satalecka, K; Scalzotto, V; Scapin, V; Schultz, C; Schweizer, T; Shayduk, M; Shore, S N; Sierpowska-Bartosik, A; Sillanpää, A; Sitarek, J; Sobczynska, D; Spanier, F; Spiro, S; Stamerra, A; Steinke, B; Struebig, J C; Suric, T; Takalo, L; Tavecchio, F; Temnikov, P; Terzic, T; Tescaro, D; Teshima, M; Torres, D F; Vankov, H; Wagner, R M; Weitzel, Q; Zabalza, V; Zandanel, F; Zanin, R; Neronov, A; Semikoz, D V

    2010-01-01

    Context: Part of the very high energy $\\gamma$-ray radiation coming from extragalactic sources is absorbed through the pair production process on the extragalactic background light photons. Extragalactic magnetic fields alter the trajectories of these cascade pairs and, in turn, convert cosmic background photons to gamma-ray energies by inverse Compton scattering. These secondary photons can form an extended halo around bright VHE sources. Aims: We searched for an extended emission around the bright blazars Mrk 421 and Mrk 501 using the MAGIC telescope data. Methods: If extended emission is present, the angular distribution of reconstructed gamma-ray arrival directions around the source is broader than for a point-like source. In the analysis of a few tens of hours of observational data taken from Mrk 421 and Mrk 501 we used a newly developed method that provides better angular resolution. This method is based on the usage of multidimensional decision trees. Comparing the measured shapes of angular distributi...

  16. Search for the Exclusive Radiative Decays B -> rho gamma and B -> omega gamma

    CERN Document Server

    Aubert, Bernard; Gaillard, Jean-Marc; Hicheur, A; Karyotakis, Yu; Lees, J P; Robbe, P; Tisserand, V; Zghiche, A; Palano, A; Pompili, A; Chen, J C; Qi, N D; Rong, G; Wang, P; Zhu, Y S; Eigen, G; Ofte, I; Stugu, B; Abrams, G S; Borgland, A W; Breon, A B; Brown, D N; Button-Shafer, J; Cahn, R N; Charles, E; Gill, M S; Gritsan, A V; Groysman, Y; Jacobsen, R G; Kadel, R W; Kadyk, J; Kerth, L T; Kolomensky, Yu G; Kral, J F; Le Clerc, C; Levi, M E; Lynch, G; Mir, L M; Oddone, P J; Orimoto, T J; Pripstein, M; Roe, N A; Romosan, A; Ronan, Michael T; Shelkov, V G; Telnov, A V; Wenzel, W A; Harrison, T J; Hawkes, C M; Knowles, D J; O'Neale, S W; Penny, R C; Watson, A T; Watson, N K; Deppermann, T; Goetzen, K; Koch, H; Lewandowski, B; Peters, K; Schmücker, H; Steinke, M; Barlow, N R; Bhimji, W; Boyd, J T; Chevalier, N; Clark, P J; Cottingham, W N; MacKay, C; Wilson, F F; Abe, K; Hearty, C; Mattison, T S; McKenna, J A; Thiessen, D; Jolly, S; McKemey, A K; Blinov, V E; Bukin, A D; Buzykaev, A R; Golubev, V B; Ivanchenko, V N; Korol, A A; Kravchenko, E A; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Yushkov, A N; Best, D; Chao, M; Kirkby, D; Lankford, A J; Mandelkern, M A; McMahon, S; Stoker, D P; Buchanan, C; Chun, S; Hadavand, H K; Hill, E J; MacFarlane, D B; Paar, H P; Prell, S; Rahatlou, S; Raven, G; Schwanke, U; Sharma, V; Berryhill, J W; Campagnari, C; Dahmes, B; Hart, P A; Kuznetsova, N P; Levy, S L; Long, O; Lu, A; Mazur, M A; Richman, J D; Verkerke, W; Beringer, J; Eisner, A M; Grothe, M; Heusch, C A; Lockman, W S; Pulliam, T; Schalk, T L; Schmitz, R E; Schumm, B A; Seiden, A; Turri, M; Walkowiak, W; Williams, D C; Wilson, M G; Chen, E; Dubois-Felsmann, G P; Dvoretskii, A; Hitlin, D G; Porter, F C; Ryd, A; Samuel, A; Yang, S; Jayatilleke, S M; Mancinelli, G; Meadows, B T; Sokoloff, M D; Barillari, T; Bloom, P; Ford, W T; Nauenberg, U; Olivas, A; Rankin, P; Roy, J; Smith, J G; Van Hoek, W C; Zhang, L; Harton, J L; Hu, T; Krishnamurthy, M; Soffer, A; Toki, W H; Wilson, R J; Zhang, J; Altenburg, D; Brandt, T; Brose, J; Colberg, T; Dickopp, M; Dubitzky, R S; Hauke, A; Maly, E; Müller-Pfefferkorn, R; Otto, S; Schubert, Klaus R; Schwierz, R; Spaan, B; Wilden, L; Bernard, D; Bonneaud, G R; Brochard, F; Cohen-Tanugi, J; Ferrag, S; T'Jampens, S; Thiebaux, C; Vasileiadis, G; Verderi, M; Anjomshoaa, A; Bernet, R; Khan, A; Lavin, D; Muheim, F; Playfer, S; Swain, J E; Tinslay, J; Falbo, M; Borean, C; Bozzi, C; Piemontese, L; Sarti, A; Treadwell, E; Anulli, F; Baldini-Ferroli, R; Calcaterra, A; De Sangro, R; Falciai, D; Finocchiaro, G; Patteri, P; Peruzzi, I M; Piccolo, M; Zallo, A; Bagnasco, S; Buzzo, A; Contri, R; Crosetti, G; Lo Vetere, M; Macri, M; Monge, M R; Passaggio, S; Pastore, F C; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Bailey, S; Morii, M; Bartoldus, R; Grenier, G J; Mallik, U; Cochran, J; Crawley, H B; Lamsa, J; Meyer, W T; Rosenberg, E I; Yi, J; Davier, M; Grosdidier, G; Höcker, A; Lacker, H M; Laplace, S; Le Diberder, F R; Lepeltier, V; Lutz, A M; Petersen, T C; Plaszczynski, S; Schune, M H; Tantot, L; Trincaz-Duvoid, S; Wormser, G; Bionta, R M; Brigljevic, V; Lange, D J; Van Bibber, K; Wright, D M; Bevan, A J; Fry, J R; Gabathuler, Erwin; Gamet, R; George, M; Kay, M; Payne, D J; Sloane, R J; Touramanis, C; Aspinwall, M L; Bowerman, D A; Dauncey, P D; Egede, U; Eschrich, I; Morton, G W; Nash, J A; Sanders, P; Smith, D; Taylor, G P; Back, J J; Bellodi, G; Dixon, P; Harrison, P F; Potter, R J L; Shorthouse, H W; Strother, P; Vidal, P B; Cowan, G; Flächer, H U; George, S; Green, M G; Kurup, A; Marker, C E; McMahon, T R; Ricciardi, S; Salvatore, F; Vaitsas, G; Winter, M A; Brown, D; Davis, C L; Allison, J; Barlow, R J; Forti, A C; Jackson, F; Lafferty, G D; Lyon, A J; Savvas, N; Weatherall, J H; Williams, J C; Farbin, A; Jawahery, A; Lillard, V; Roberts, D A; Schieck, J; Blaylock, G; Dallapiccola, C; Flood, K T; Hertzbach, S S; Kofler, R; Koptchev, V B; Moore, T B; Stängle, H; Willocq, S; Brau, B; Cowan, R; Sciolla, G; Taylor, F; Yamamoto, R K; Milek, M; Patel, P M; Palombo, F; Bauer, J M; Cremaldi, L M; Eschenburg, V; Kroeger, R; Reidy, J; Sanders, D A; Summers, D J; Hast, C; Taras, P; Rene, J A; Nicholson, H; Cartaro, C; Cavallo, N; De Nardo, Gallieno; Fabozzi, F; Gatto, C; Lista, L; Paolucci, P; Piccolo, D; Sciacca, C; LoSecco, J M; Alsmiller, J R G; Gabriel, T A; Brau, J E; Frey, R; Iwasaki, M; Potter, C T; Sinev, N B; Strom, D; Torrence, E; Colecchia, F; Dorigo, A; Galeazzi, F; Margoni, M; Morandin, M; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Voci, C; Benayoun, M; Briand, H; Chauveau, J; David, P; La Vaissière, C de; Del Buono, L; Hamon, O; Leruste, P; Ocariz, J; Pivk, M; Roos, L; Stark, J; Manfredi, P F; Re, V; Speziali, V; Gladney, L; Guo, Q H; Panetta, J; Angelini, C; Batignani, G; Bettarini, S; Bondioli, M; Bucci, F; Calderini, G; Campagna, E

    2002-01-01

    A search for the exclusive radiative decays B->rho(770) gamma and B^0->omega(782) gamma is performed on a sample of 84 million BB-bar events collected by the BABAR detector at the PEP-II asymmetric e^+e^- collider. No significant signal is seen in any of the channels. We set preliminary upper limits of BR[B^0->rho^0 gamma] rho^+ gamma] omega gamma] rho gamma, we find the preliminary limit BR[B -> rho gamma] rho gamma]/BR[B-> K* gamma] < 0.047 at 90% Confidence Level.

  17. Gamma-ray-selected AGN

    Science.gov (United States)

    Giommi, Paolo

    2016-08-01

    The gamma-ray band is the most energetic part of the electromagnetic spectrum. As such it is also where selection effects are most severe, as it can only be reached by the most extreme non-thermal AGN. Blazars, with their emission dominated by non-thermal blue-shifted radiation arising in a relativistic jet pointed in the direction of the observer, naturally satisfy this though requirement. For this reason, albeit these sources are intrisically very rare (orders of magnitude less abundant than radio quiet AGN of the same optical magnitude) they almost completely dominate the extragalactic gamma-ray and very high energy sky. I will discuss the emission of different types of blazars and the selection effects that are at play in the gamma-ray band based on recent results from the current generation of gamma-ray astronomy satellites, ground-based Cherenkov telescopes, and Monte Carlo simulations.

  18. Study of the $e^+ e^- \\to Z\\gamma\\gamma \\to q\\overline{q}\\gamma\\gamma$ Process at LEP

    CERN Document Server

    Acciarri, M; Adriani, O; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Ambrosi, G; Anderhub, H; Andreev, V P; Angelescu, T; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, L; Balandras, A; Baldew, S V; Todorova-Nová, S; Banerjee, Sw; Barczyk, A; Barillère, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Bhattacharya, S; Biasini, M; Biglietti, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brochu, F; Buffini, A; Buijs, A; Burger, J D; Burger, W J; Cai, X D; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Castellini, G; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Cesaroni, F; Chamizo-Llatas, M; Chang, Y H; Chaturvedi, U K; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Civinini, C; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; Cotorobai, F; de la Cruz, B; Csilling, Akos; Cucciarelli, S; Dai, T S; van Dalen, J A; D'Alessandro, R; De Asmundis, R; Déglon, P L; Degré, A; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Van Dierendonck, D N; Dionisi, C; Dittmar, Michael; Dominguez, A; Doria, A; Dova, M T; Duchesneau, D; Dufournaud, D; Duinker, P; El-Mamouni, H; Engler, A; Eppling, F J; Erné, F C; Ewers, A; Extermann, Pierre; Fabre, M; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, Marta; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gau, S S; Gentile, S; Gheordanescu, N; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hasan, A; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hidas, P; Hirschfelder, J; Hofer, H; Holzner, G; Hoorani, H; Hou, S R; Hu, Y; Iashvili, I; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Khan, R A; Käfer, D; Kaur, M; Kienzle-Focacci, M N; Kim, D; Kim, J K; Kirkby, Jasper; Kiss, D; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Kopp, A; Koutsenko, V F; Kräber, M H; Krämer, R W; Krenz, W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Lee, H J; Le Goff, J M; Leiste, R; Levchenko, P M; Li Chuan; Likhoded, S A; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Lübelsmeyer, K; Luci, C; Luckey, D; Lugnier, L; Luminari, L; Lustermann, W; Ma Wen Gan; Maity, M; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Mans, J; Marian, G; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Von der Mey, M; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Moulik, T; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nisati, A; Nowak, H; Ofierzynski, R A; Organtini, G; Oulianov, A; Palomares, C; Pandoulas, D; Paoletti, S; Paolucci, P; Paramatti, R; Park, H K; Park, I H; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pieri, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Postema, H; Pothier, J; Prokofiev, D O; Prokofev, D; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Raven, G; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Rodin, J; Roe, B P; Romero, L; Rosca, A; Rosier-Lees, S; Roth, S; Rosenbleck, C; Roux, B; Rubio, Juan Antonio; Ruggiero, G; Rykaczewski, H; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Sanders, M P; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schopper, Herwig Franz; Schotanus, D J; Schwering, G; Sciacca, C; Seganti, A; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Smith, B; Spillantini, P; Steuer, M; Stickland, D P; Stone, A; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S V; Suter, H; Swain, J D; Szillási, Z; Sztaricskai, T; Tang, X W; Tauscher, Ludwig; Taylor, L; Tellili, B; Teyssier, D; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Uchida, Y; Ulbricht, J; Valente, E; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Vorvolakos, A; Wadhwa, M; Wallraff, W; Wang, M; Wang, X L; Wang, Z M; Weber, A; Weber, M; Wienemann, P; Wilkens, H; Wu, S X; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Ye, J B; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhu, G Y; Zhu, R Y; Zichichi, A; Zilizi, G; Zimmermann, B; Zöller, M

    2001-01-01

    The process e^+e^- -> Z gamma gamma -> q q~ gamma gamma$ is studied in 0.5\\,fb-1$ of data collected with the L3 detector at centre-of-mass energies between 130.1 GeV and 201.7 GeV. Cross sections are measured and found to be consistent with the Standard Model expectations. The study of the least energetic photon constrains the quartic gauge boson couplings to -0.008 GeV-2 < a_0/\\Lambda^2 < 0.005 GeV-2 and -0.007 GeV-2 < a_c/\\Lambda^2 < 0.011 GeV-2, at 95% confidence level.

  19. The GAMMA-400 Space Experiment

    Science.gov (United States)

    Bongi, M.

    2014-06-01

    GAMMA-400 is a new space experiment which will study gamma rays and cosmic rays from about 100 MeV up to some TeVs. The proposed instrument has an angular resolution ˜ 0.1 degrees at 10 GeV and better than ˜ 0.02 degrees above 100 GeV, and an energy resolution ˜ 1% at E > 100 GeV for gamma rays. With these characteristics the experiment will be able to contribute to the search for signatures of Dark Matter, and to the study of Galactic and ex-tragalactic gamma sources and diffuse emission. A large segmented calorimeter more than 25 X0 deep will allow the study of high-energy electrons, and the measurement of the flux of protons and nuclei up to the "knee" region.

  20. Gamma camera system

    International Nuclear Information System (INIS)

    The invention provides a composite solid state detector for use in deriving a display, by spatial coordinate information, of the distribution or radiation emanating from a source within a region of interest, comprising several solid state detector components, each having a given surface arranged for exposure to impinging radiation and exhibiting discrete interactions therewith at given spatially definable locations. The surface of each component and the surface disposed opposite and substantially parallel thereto are associated with impedence means configured to provide for each opposed surface outputs for signals relating the given location of the interactions with one spatial coordinate parameter of one select directional sense. The detector components are arranged to provide groupings of adjacently disposed surfaces mutually linearly oriented to exhibit a common directional sense of the spatial coordinate parameter. Means interconnect at least two of the outputs associated with each of the surfaces within a given grouping for collecting the signals deriving therefrom. The invention also provides a camera system for imaging the distribution of a source of gamma radiation situated within a region of interest