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Search Results: 1 - 10 of 461774 matches for " A. Chepurnov "
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Extending Big Power Law in the Sky with Turbulence Spectra from WHAM data
A. Chepurnov,A. Lazarian
Physics , 2009, DOI: 10.1088/0004-637X/710/1/853
Abstract: We use the data of Wisconsin H$\alpha$ Mapper (WHAM) to test the hypothesis of whether the amplitudes and spectrum of density fluctuations measured by WHAM can be matched to the data obtained for interstellar scintillations and scattering. To do this, first of all, we adjusted the mean level of signal in the adjacent patches of the data. Then, assuming that the spectrum is Kolmogorov, we successfully matched the amplitudes of turbulence obtained from the WHAM data and the interstellar density fluctuations reported in the existing literature. As a result, we conclude that the existing data is consistent with the Kolmogorov cascade which spans from $10^6$ to $10^{17}$ $m$.
The galactic foreground angular spectra
A. V. Chepurnov
Physics , 2002, DOI: 10.1080/10556799808232095
Abstract: Galactic synchrotron and free-free foregrounds angular spectra are analytically estimated with account for interstellar turbulence and radiating process physics. Unknown parameters of the spectra are obtained by fitting to observational data.
Crimean-Congo Hemorrhagic Fever Virus Entry into Host Cells Occurs through the Multivesicular Body and Requires ESCRT Regulators
Olena Shtanko,Raisa A. Nikitina,Cengiz Z. Altuntas,Alexander A. Chepurnov,Robert A. Davey
PLOS Pathogens , 2014, DOI: doi/10.1371/journal.ppat.1004390
Abstract: Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne bunyavirus causing outbreaks of severe disease in humans, with a fatality rate approaching 30%. There are no widely accepted therapeutics available to prevent or treat the disease. CCHFV enters host cells through clathrin-mediated endocytosis and is subsequently transported to an acidified compartment where the fusion of virus envelope with cellular membranes takes place. To better understand the uptake pathway, we sought to identify host factors controlling CCHFV transport through the cell. We demonstrate that after passing through early endosomes in a Rab5-dependent manner, CCHFV is delivered to multivesicular bodies (MVBs). Virus particles localized to MVBs approximately 1 hour after infection and affected the distribution of the organelle within cells. Interestingly, blocking Rab7 activity had no effect on association of the virus with MVBs. Productive virus infection depended on phosphatidylinositol 3-kinase (PI3K) activity, which meditates the formation of functional MVBs. Silencing Tsg101, Vps24, Vps4B, or Alix/Aip1, components of the endosomal sorting complex required for transport (ESCRT) pathway controlling MVB biogenesis, inhibited infection of wild-type virus as well as a novel pseudotyped vesicular stomatitis virus (VSV) bearing CCHFV glycoprotein, supporting a role for the MVB pathway in CCHFV entry. We further demonstrate that blocking transport out of MVBs still allowed virus entry while preventing vesicular acidification, required for membrane fusion, trapped virions in the MVBs. These findings suggest that MVBs are necessary for infection and are the sites of virus-endosome membrane fusion.
Distributed Can-Bus Based Beam Diagnostic System for Pulse Race-Track Microtron
A. Chepurnov,I. Gribov,V. Shvedunov,F. Nedeoglo,O. Novojilov,S. Dudnikov
Physics , 2001,
Abstract: Very compact 70 MeV pulse race-track microtron is under construction now. To acquire outputs of beam-current transformers on every orbit and pulses of high voltage and RF field a distributed multi-channel beam diagnostic system was developed. Each acquisition controller consists of four fast differential amplifiers and one DSP-based micro-controller with on-chip ADC and CAN-bus controller. Each amplifier is coupled with beam-current transformer and has bandwidth of up to 150MHz and gain of up to 10. One of four channels is acquired during a measurement cycle. Another channel could be selected between two following pulses. All the controllers are connected via optically coupled CAN-bus with a host diskless PC running under Linux with the RTLinux extension. Dedicated software of the system consists of low level acquisition software for DSP, network software for controllers and host PC, application software for PC to present date for operator and control system. Standard CAN application layers were considered but refused because of the closed character of the whole system and centralised synchronisation of the whole system. Dedicated software of the system consists from low level acquisition software for DSP, network software for controllers and host PC, application software for PC to present date for operator and control system. Standard CAN application layers were considered but refused because of closed character of the whole system and centralised synchronisation of the whole system.
The Turbulence Velocity Power Spectrum of Neutral Hydrogen in the Small Magellanic Cloud
Alexey Chepurnov,Blakesley Burkhart,Alex Lazarian,Snezana Stanimirovic
Physics , 2015, DOI: 10.1088/0004-637X/810/1/33
Abstract: We present the results of the Velocity Coordinate Spectrum (VCS) technique to calculate the velocity power spectrum of turbulence in the Small Magellanic Cloud (SMC) in 21cm emission. We have obtained a velocity spectral index of -3.85 and an injection scale of 2.3 kpc. The spectral index is steeper than the Kolmogorov index which is expected for shock-dominated turbulence which is in agreement with past works on the SMC gas dynamics. The injection scale of 2.3 kpc suggests that tidal interactions with the Large Magellanic Cloud are the dominate driver of turbulence in this dwarf galaxy. This implies turbulence maybe driven by multiple mechanisms in galaxies in addition to supernova injection and that galaxy-galaxy interactions may play an important role.
Perspectives to measure neutrino-nuclear neutral current coherent scattering with two-phase emission detector
RED Collaboration,D. Yu. Akimov,I. S. Alexandrov,V. I. Aleshin,V. A. Belov,A. I. Bolozdynya,A. A. Burenkov,A. S. Chepurnov,M. V. Danilov,A. V. Derbin,V. V. Dmitrenko,A. G. Dolgolenko,D. A. Egorov,Yu. V. Efremenko,A. V. Etenko,M. B. Gromov,M. A. Gulin,S. V. Ivakhin,V. A. Kantserov,V. A. Kaplin,A. K. Karelin,A. V. Khromov,M. A. Kirsanov,S. G. Klimanov,A. S. Kobyakin,A. M. Konovalov,A. G. Kovalenko,V. I. Kopeikin,T. D. Krakhmalova,A. V. Kuchenkov,A. V. Kumpan,E. A. Litvinovich,G. A Lukyanchenko,I. N. Machulin,V. P. Martemyanov,N. N. Nurakhov,D. G. Rudik,I. S. Saldikov,M. D. Skorokhatov,V. V. Sosnovtsev,V. N. Stekhanov,M. N. Strikhanov,S. V. Sukhotin,V. G. Tarasenkov,G. V. Tikhomirov,O. Ya. Zeldovich
Physics , 2012, DOI: 10.1088/1748-0221/8/10/P10023
Abstract: We propose to detect and to study neutrino neutral current coherent scattering off atomic nuclei with a two-phase emission detector using liquid xenon as a working medium. Expected signals and backgrounds are calculated for two possible experimental sites: Kalinin Nuclear Power Plant in the Russian Federation and Spallation Neutron Source at the Oak Ridge National Laboratory in the USA. Both sites have advantages as well as limitations. However the experiment looks feasible at either location. Preliminary design of the detector and supporting R&D program are discussed.
Light Yield in DarkSide-10: a Prototype Two-phase Liquid Argon TPC for Dark Matter Searches
T. Alexander,D. Alton,K. Arisaka,H. O. Back,P. Beltrame,J. Benziger,G. Bonfini,A. Brigatti,J. Brodsky,L. Cadonati,F. Calaprice,A. Candela,H. Cao,P. Cavalcante,A. Chavarria,A. Chepurnov,D. Cline,A. G. Cocco,C. Condon,D. D'Angelo,S. Davini,E. De Haas,A. Derbin,G. Di Pietro,I. Dratchnev,D. Durben,A. Empl,A. Etenko,A. Fan,G. Fiorillo,K. Fomenko,F. Gabriele,C. Galbiati,S. Gazzana,C. Ghag,C. Ghiano,A. Goretti,L. Grandi,M. Gromov,M. Guan,C. Guo,G. Guray,E. V. Hungerford,Al. Ianni,An. Ianni,A. Kayunov,K. Keeter,C. Kendziora,S. Kidner,V. Kobychev,G. Koh,D. Korablev,G. Korga,E. Shields,P. Li,B. Loer,P. Lombardi,C. Love,L. Ludhova,L. Lukyanchenko,A. Lund,K. Lung,Y. Ma,I. Machulin,J. Maricic,C. J. Martoff,Y. Meng,E. Meroni,P. D. Meyers,T. Mohayai,D. Montanari,M. Montuschi,P. Mosteiro,B. Mount,V. Muratova,A. Nelson,A. Nemtzow,N. Nurakhov,M. Orsini,F. Ortica,M. Pallavicini,E. Pantic,S. Parmeggiano,R. Parsells,N. Pelliccia,L. Perasso,F. Perfetto,L. Pinsky,A. Pocar,S. Pordes,G. Ranucci,A. Razeto,A. Romani,N. Rossi,P. Saggese,R. Saldanha,C. Salvo,W. Sands,M. Seigar,D. Semenov,M. Skorokhvatov,O. Smirnov,A. Sotnikov,S. Sukhotin,Y. Suvorov,R. Tartaglia,J. Tatarowicz,G. Testera,A. Teymourian,J. Thompson,E. Unzhakov,R. B. Vogelaar,H. Wang,S. Westerdale,M. Wojcik,A. Wright,J. Xu,C. Yang,S. Zavatarelli,M. Zehfus,W. Zhong,G. Zuzel
Physics , 2012, DOI: 10.1016/j.astropartphys.2013.08.004
Abstract: As part of the DarkSide program of direct dark matter searches using liquid argon TPCs, a prototype detector with an active volume containing 10 kg of liquid argon, DarkSide-10, was built and operated underground in the Gran Sasso National Laboratory in Italy. A critically important parameter for such devices is the scintillation light yield, as photon statistics limits the rejection of electron-recoil backgrounds by pulse shape discrimination. We have measured the light yield of DarkSide-10 using the readily-identifiable full-absorption peaks from gamma ray sources combined with single-photoelectron calibrations using low-occupancy laser pulses. For gamma lines of energies in the range 122-1275 keV, we get consistent light yields averaging 8.887+-0.003(stat)+-0.444(sys) p.e./keVee. With additional purification, the light yield measured at 511 keV increased to 9.142+-0.006(stat) p.e./keVee.
Solar neutrino with Borexino: results and perspectives
O. Smirnov,G. Bellini,J. Benziger,D. Bick,G. Bonfini,D. Bravo,B. Caccianiga,F. Calaprice,A. Caminata,P. Cavalcante,A. Chavarria,A. Chepurnov,D. D'Angelo,S. Davini,A. Derbin,A. Empl,A. Etenko,K. Fomenko,D. Franco,G. Fiorentini,C. Galbiati,S. Gazzana,C. Ghiano,M. Giammarchi,M. Goeger-Neff,A. Goretti,C. Hagner,E. Hungerford,Aldo Ianni,Andrea Ianni,V. Kobychev,D. Korablev,G. Korga,D. Kryn,M. Laubenstein,B. Lehnert,T. Lewke,E. Litvinovich,F. Lombardi,P. Lombardi,L. Ludhova,G. Lukyanchenko,I. Machulin,S. Manecki,W. Maneschg,F. Mantovani,S. Marcocci,Q. Meindl,E. Meroni,M. Meyer,L. Miramonti,M. Misiaszek,P. Mosteiro,V. Muratova,L. Oberauer,M. Obolensky,F. Ortica,K. Otis,M. Pallavicini,L. Papp,L. Perasso,A. Pocar,G. Ranucci,A. Razeto,A. Re,B. Ricci,A. Romani,N. Rossi,R. Saldanha,C. Salvo,S. Schoenert,H. Simgen,M. Skorokhvatov,A. Sotnikov,S. Sukhotin,Y. Suvorov,R. Tartaglia,G. Testera,D. Vignaud,R. B. Vogelaar,F. von Feilitzsch,H. Wang,J. Winter,M. Wojcik,A. Wright,M. Wurm,O. Zaimidoroga,S. Zavatarelli,K. Zuber,G. Zuzel
Physics , 2014, DOI: 10.1134/S1063779615020185
Abstract: Borexino is a unique detector able to perform measurement of solar neutrinos fluxes in the energy region around 1 MeV or below due to its low level of radioactive background. It was constructed at the LNGS underground laboratory with a goal of solar $^{7}$Be neutrino flux measurement with 5\% precision. The goal has been successfully achieved marking the end of the first stage of the experiment. A number of other important measurements of solar neutrino fluxes have been performed during the first stage. Recently the collaboration conducted successful liquid scintillator repurification campaign aiming to reduce main contaminants in the sub-MeV energy range. With the new levels of radiopurity Borexino can improve existing and challenge a number of new measurements including: improvement of the results on the Solar and terrestrial neutrino fluxes measurements; measurement of pp and CNO solar neutrino fluxes; search for non-standard interactions of neutrino; study of the neutrino oscillations on the short baseline with an artificial neutrino source (search for sterile neutrino) in context of SOX project.
Measurement of geo-neutrinos from 1353 days of Borexino
G. Bellini,J. Benziger,D. Bick,G. Bonfini,D. Bravo,M. Buizza Avanzini,B. Caccianiga,L. Cadonati,F. Calaprice,P. Cavalcante,A. Chavarria,A. Chepurnov,D. D'Angelo,S. Davini,A. Derbin,A. Empl,A. Etenko,G. Fiorentini,K. Fomenko,D. Franco,C. Galbiati,S. Gazzana,C. Ghiano,M. Giammarchi,M. Goeger-Neff,A. Goretti,L. Grandi,C. Hagner,E. Hungerford,Aldo Ianni,Andrea Ianni,V. V. Kobychev,D. Korablev,G. Korga,Y. Koshio,D. Kryn,M. Laubenstein,T. Lewke,E. Litvinovich,B. Loer,P. Lombardi,F. Lombardi,L. Ludhova,G. Lukyanchenko,I. Machulin,S. Manecki,W. Maneschg,F. Mantovani,G. Manuzio,Q. Meindl,E. Meroni,L. Miramonti,M. Misiaszek,P. Mosteiro,V. Muratova,L. Oberauer,M. Obolensky,F. Ortica,K. Otis,M. Pallavicini,L. Papp,L. Perasso,S. Perasso,A. Pocar,G. Ranucci,A. Razeto,A. Re,B. Ricci,A. Romani,N. Rossi,A. Sabelnikov,R. Saldanha,C. Salvo,S. Schoenert,H. Simgen,M. Skorokhvatov,O. Smirnov,A. Sotnikov,S. Sukhotin,Y. Suvorov,R. Tartaglia,G. Testera,D. Vignaud,R. B. Vogelaar,F. von Feilitzsch,J. Winter,M. Wojcik,A. Wright,M. Wurm,J. Xu,O. Zaimidoroga,S. Zavatarelli,G. Zuzel
Physics , 2013, DOI: 10.1016/j.physletb.2013.04.030
Abstract: We present a measurement of the geo--neutrino signal obtained from 1353 days of data with the Borexino detector at Laboratori Nazionali del Gran Sasso in Italy. With a fiducial exposure of (3.69 $\pm$ 0.16) $\times$ $10^{31}$ proton $\times$ year after all selection cuts and background subtraction, we detected (14.3 $\pm$ 4.4) geo-neutrino events assuming a fixed chondritic mass Th/U ratio of 3.9. This corresponds to a geo-neutrino signal $S_{geo}$ = (38.8 $\pm$ 12.0) TNU with just a 6 $\times$ $10^{-6}$ probability for a null geo-neutrino measurement. With U and Th left as free parameters in the fit, the relative signals are $S_{\mathrm{Th}}$ = (10.6 $\pm$ 12.7) TNU and $S_\mathrm{U}$ = (26.5 $\pm$ 19.5) TNU. Borexino data alone are compatible with a mantle geo--neutrino signal of (15.4 $\pm$ 12.3) TNU, while a combined analysis with the KamLAND data allows to extract a mantle signal of (14.1 $\pm$ 8.1) TNU. Our measurement of a reactor anti--neutrino signal $S_{react}$ = 84.5$^{+19.3}_{-18.9}$ TNU is in agreement with expectations in the presence of neutrino oscillations.
Low-energy (anti)neutrino physics with Borexino: Neutrinos from the primary proton-proton fusion process in the Sun
P. Mosteiro,G. Bellini,J. Benziger,D. Bick,G. Bonfini,D. Bravo,B. Caccianiga,L. Cadonati,F. Calaprice,A. Caminata,P. Cavalcante,A. Chavarria,A. Chepurnov,D. D'Angelo,S. Davini,A. Derbin,A. Empl,A. Etenko,K. Fomenko,D. Franco,F. Gabriele,C. Galbiati,S. Gazzana,C. Ghiano,M. Giammarchi,M. Goeger-Neff,A. Goretti,M. Gromov,C. Hagner,E. Hungerford,Al. Ianni,An. Ianni,V. Kobychev,D. Korablev,G. Korga,D. Kryn,M. Laubenstein,B. Lehnert,T. Lewke,E. Litvinovich,F. Lombardi,P. Lombardi,L. Ludhova,G. Lukyanchenko,I. Machulin,S. Manecki,W. Maneschg,S. Marcocci,Q. Meindl,E. Meroni,M. Meyer,L. Miramonti,M. Misiaszek,M. Montuschi,V. Muratova,L. Oberauer,M. Obolensky,F. Ortica,K. Otis,M. Pallavicini,L. Papp,L. Perasso,A. Pocar,G. Ranucci,A. Razeto,A. Re,A. Romani,N. Rossi,R. Saldanha,C. Salvo,S. Schoenert,H. Simgen,M. Skorokhvatov,O. Smirnov,A. Sotnikov,S. Sukhotin,Y. Suvorov,R. Tartaglia,G. Testera,D. Vignaud,R. B. Vogelaar,F. von Feilitzsch,H. Wang,J. Winter,M. Wojcik,A. Wright,M. Wurm,O. Zaimidoroga,S. Zavatarelli,K. Zuber,G. Zuzel
Physics , 2015, DOI: 10.1016/j.nuclphysbps.2015.06.023
Abstract: The Sun is fueled by a series of nuclear reactions that produce the energy that makes it shine. The primary reaction is the fusion of two protons into a deuteron, a positron and a neutrino. These neutrinos constitute the vast majority of neutrinos reaching Earth, providing us with key information about what goes on at the core of our star. Several experiments have now confirmed the observation of neutrino oscillations by detecting neutrinos from secondary nuclear processes in the Sun; this is the first direct spectral measurement of the neutrinos from the keystone proton-proton fusion. This observation is a crucial step towards the completion of the spectroscopy of pp-chain neutrinos, as well as further validation of the LMA-MSW model of neutrino oscillations.
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