338 results on '"V. Astakhov"'
Search Results
302. ChemInform Abstract: RK. VON WISMUTNITRAT MIT KALIUMDIPHOSPHAT
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L. A. Tezikova, N. N. Chudinova, and K. V. Astakhov
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Chemistry ,Stereochemistry ,General Medicine - Published
- 1972
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303. Evaluation of ccomputational complexity and shortcomings of non-binary low density decoding algorithms.
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V V Glotov, A V Bashkirov, N V Astakhov, A A Pirogov, and S N Panychev
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- 2019
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304. CdSe/ZnSe quantum dots formed by low temperature epitaxy and in-situ annealing: Properties and growth optimization
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U. Bass, Suddhasatta Mahapatra, W. Ossau, Karl Brunner, Tobias Kiessling, G. V. Astakhov, J. Geurts, and C. Schumacher
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Materials science ,Condensed matter physics ,Annealing (metallurgy) ,business.industry ,General Physics and Astronomy ,Thermal treatment ,Epitaxy ,Quantum dot ,X-ray crystallography ,Optoelectronics ,business ,Luminescence ,Order of magnitude ,Molecular beam epitaxy - Abstract
The formation of CdSe/ZnSe quantum dots by a method combining a low temperature MBE growth of a CdSe layer and its subsequent in-situ annealing at temperatures between 280−340◦C has been studied. The thermal treatment results in a re-organization of the surface from a nearly two-dimensional layer to an ensemble of three-dimensional dot-like features. In this work we optimized the different growth and annealing parameters of this process and compared the properties of the resultant dots with those of dots grown by conventional MBE at 300◦C. It is demonstrated that the luminescence properties of the dots for both growth techniques are comparable but the areal density achieved by the in-situ annealing technique is an order of magnitude lower. From high resolution X-ray diffraction results, it could be established that no desorption takes place despite significantly long annealing duration. Beyond a nominal coverage of 3.5 ML CdSe, stacking faults are generated, leading to a gradual decrease in luminescence intensities and an overlap of pendellosung fringes in X-ray diffractograms.
305. Excitons and trions in II-VI quantum wells with modulation doping
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Dmitri R. Yakovlev, V. P. Kochereshko, Jacek Kossut, Tomasz Wojtowicz, W. Ossau, G. Landwehr, G. V. Astakhov, and Grzegorz Karczewski
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Condensed Matter::Quantum Gases ,Physics ,Photoluminescence ,Condensed matter physics ,Condensed Matter::Other ,Exciton ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter Physics ,Spectral line ,Electronic, Optical and Magnetic Materials ,Magnetic field ,Condensed Matter::Materials Science ,Photoluminescence excitation ,Trion ,Quantum well ,Biexciton - Abstract
Modifications of exciton and trion photoluminescence and photoluminescence excitation spectra have been studied in modulation-doped CdTe/(Cd,Mg)Te quantum well structures as a function of electron concentration and magnetic fields. These modifications have been explained in terms of combined exciton–electron processes.
306. Milliwatt terahertz harmonic generation from topological insulator metamaterials
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Klaas-Jan Tielrooij, Alessandro Principi, David Saleta Reig, Alexander Block, Sebin Varghese, Steffen Schreyeck, Karl Brunner, Grzegorz Karczewski, Igor Ilyakov, Oleksiy Ponomaryov, Thales V. A. G. de Oliveira, Min Chen, Jan-Christoph Deinert, Carmen Gomez Carbonell, Sergio O. Valenzuela, Laurens W. Molenkamp, Tobias Kiessling, Georgy V. Astakhov, Sergey Kovalev, European Commission, Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Leverhulme Trust, Universität Würzburg, Advanced Nanomaterials & Devices, and Ultrafast Dynamics in Nanoscale Systems
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Nonlinear optics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Metamaterials ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,High-harmonic generation ,FOS: Physical sciences ,Atomic and Molecular Physics, and Optics ,Terahertz optics ,Electronic, Optical and Magnetic Materials ,Physics - Optics ,Optics (physics.optics) - Abstract
Achieving efficient, high-power harmonic generation in the terahertz spectral domain has technological applications, for example, in sixth generation (6G) communication networks. Massless Dirac fermions possess extremely large terahertz nonlinear susceptibilities and harmonic conversion efficiencies. However, the observed maximum generated harmonic power is limited, because of saturation effects at increasing incident powers, as shown recently for graphene. Here, we demonstrate room-temperature terahertz harmonic generation in a BiSe topological insulator and topological-insulator-grating metamaterial structures with surface-selective terahertz field enhancement. We obtain a third-harmonic power approaching the milliwatt range for an incident power of 75 mW—an improvement by two orders of magnitude compared to a benchmarked graphene sample. We establish a framework in which this exceptional performance is the result of thermodynamic harmonic generation by the massless topological surface states, benefiting from ultrafast dissipation of electronic heat via surface-bulk Coulomb interactions. These results are an important step towards on-chip terahertz (opto)electronic applications., K.J.T. acknowledges funding from the European Union’s Horizon 2020 research and innovation program under Grant Agreement No. 804349 (ERC StG CUHL), RYC fellowship No. RYC-2017-22330, and IAE project PID2019-111673GB-I00. ICN2 was supported by the Severo Ochoa program from Spanish MINECO Grant No. SEV-2017-0706. A.P. acknowledges support from the European Commission under the EU Horizon 2020 MSCA-RISE-2019 programme (project 873028 HYDROTRONICS) and from the Leverhulme Trust under the grant RPG-2019-363. S.S., K.B., T.K., and L.W.M. acknowledge support by the SFB1170 (DFG project ID 258499086). C.G. and S.O.V. acknowledge support from the European Union’s Horizon 2020 FET-PROACTIVE project TOCHA under grant agreement 824140. T.K., L.W.M., and G.V.A. acknowledge the financial support from the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter (EXC 2147, 390858490).
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307. Investigation of spin transport in semiconductors by spatially resolved two-color hanle-moke measurements
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W. Ossau, H. Hoffmann, J.-H. Quast, Laurens W. Molenkamp, and G. V. Astakhov
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Physics ,Spin pumping ,Condensed matter physics ,Spintronics ,Spin polarization ,Spin wave ,Spin Hall effect ,Spinplasmonics ,Spin diffusion ,Spin echo ,Condensed Matter::Strongly Correlated Electrons ,Statistical and Nonlinear Physics ,Condensed Matter Physics - Abstract
We report on a considerable impact of light on spin transport in unstrained n -type GaAs . Increasing the intensity of optical spin pumping results in a significant expansion of spin diffusion. Furthermore, in the regime of strong spin pumping the spin gradient, which can be interpreted in terms of a spin outflow from the injection point is enhanced by application of a weak magnetic field. In addition we report on optical spin pumping of modulation doped CdTe -based quantum wells. Using a two-color Hanle-MOKE technique, we find a spin relaxation time of 34 ns in the nearly unperturbed electron gas. Independent variation of pump and probe energies demonstrates the presence of additional electrons in the quantum well, whose spin relaxation time is substantially shorter.
308. Room-temperature near-infrared silicon carbide nanocrystalline emitters based on optically aligned spin defects
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Michael Trupke, D. Simin, Anke Krueger, G. V. Astakhov, V. A. Soltamov, P. G. Baranov, F. Fuchs, E. N. Mokhov, Andreas Muzha, Nadezda V. Tarakina, and Vladimir Dyakonov
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Condensed Matter - Materials Science ,Materials science ,Photoluminescence ,Physics and Astronomy (miscellaneous) ,Silicon ,Band gap ,business.industry ,Wide-bandgap semiconductor ,chemistry.chemical_element ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Nanocrystalline material ,chemistry.chemical_compound ,Nanolithography ,Nanocrystal ,chemistry ,Silicon carbide ,Optoelectronics ,business - Abstract
Bulk silicon carbide (SiC) is a very promising material system for bio-applications and quantum sensing. However, its optical activity lies beyond the near infrared spectral window for in-vivo imaging and fiber communications due to a large forbidden energy gap. Here, we report the fabrication of SiC nanocrystals and isolation of different nanocrystal fractions ranged from 600 nm down to 60 nm in size. The structural analysis reveals further fragmentation of the smallest nanocrystals into ca. 10-nm-size clusters of high crystalline quality, separated by amorphization areas. We use neutron irradiation to create silicon vacancies, demonstrating near infrared photoluminescence. Finally, we detect, for the first time, room-temperature spin resonances of these silicon vacancies hosted in SiC nanocrystals. This opens intriguing perspectives to use them not only as in-vivo luminescent markers, but also as magnetic field and temperature sensors, allowing for monitoring various physical, chemical and biological processes., Comment: 5 pages, 4 figures
309. Excitation and recombination dynamics of vacancy-related spin centers in silicon carbide
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Tilman C. Hain, Vladimir Dyakonov, G. V. Astakhov, V. A. Soltamov, P. G. Baranov, Tobias Hertel, and F. Fuchs
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Condensed Matter - Materials Science ,Photoluminescence ,Materials science ,Silicon ,Absorption cross section ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,General Physics and Astronomy ,chemistry.chemical_element ,Molecular physics ,Crystallographic defect ,Carbide ,chemistry.chemical_compound ,chemistry ,Vacancy defect ,Silicon carbide ,Excitation - Abstract
We generate silicon vacancy related defects in high-quality epitaxial silicon carbide layers by means of electron irradiation. By controlling the irradiation fluence, the defect concentration is varied over several orders of magnitude. We establish the excitation profile for optical pumping of these defects and evaluate the optimum excitation wavelength of 770 nm. We also measure the photoluminescence dynamics at room temperature and find a monoexponential decay with a characteristic lifetime of 6.1 ns. The integrated photoluminescence intensity depends linear on the excitation power density up to 20 kW/cm$^2$, indicating a relatively small absorption cross section of these defects., 4 pages, 4 figures
310. Late glacial events in the central Russian Arctic
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V. Astakhov
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geography ,geography.geographical_feature_category ,Glacial landform ,Last Glacial Maximum ,Glacier ,Paleontology ,U-shaped valley ,Oceanography ,Arctic ,Wisconsin glaciation ,Glacial period ,Ice sheet ,Geology ,Earth-Surface Processes - Abstract
Investigation of glacigenic diamictons and landforms in the central Russian Arctic has established that continental glaciation was widespread during late glacial time. Diamictons in West-Central Siberia containing marine foraminifera and mollusca include glacitectonic deformation features, and are associated with glacial landforms. These sediments are interpreted as basal tills, formed by continental glaciation which expanded from the exposed Kara Sea shelf, southwards along the western flank of the Ural Mountains. Piedmont glaciers advancing westward from the Urals were obstructed by the southward-flowing ice and were areally restricted. Simultaneously, piedmont glaciers advancing eastward from the crests of the Urals were able to expand without restriction. Alpine glaciation within the Urals was areally restricted and culminated, simultaneously, with the maximum extent of the southward-flowing shelf-based ice. In West Siberia, rapid disintegration of an Early Weichselian ice sheet by marine calving was followed by slow stagnation of the dissected mass throughout the remainder of the Weichselian. In contrast, glaciation in the Pechora Basin reached its maximum during the Middle-Late Weichselian, at least 30,000 years after the glacial maximum in western Siberia. The transition to Holocene climatic conditions was influenced by the presence of remanent decaying glacial masses.
311. Exciton-electron interaction in quantum wells with a two dimensional electron gas of low density
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Peter C. M. Christianen, C. Y. Hu, Dmitri R. Yakovlev, V. P. Kochereshko, G. V. Astakhov, W. Ossau, Robert A. Suris, and J.C. Maan
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Condensed Matter::Quantum Gases ,Materials science ,Photoluminescence ,Condensed Matter::Other ,Exciton ,Electron ,Correlated Electron Systems / High Field Magnet Laboratory (HFML) ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,Photoluminescence excitation ,Atomic physics ,Trion ,Biexciton ,Quantum well ,Bohr radius - Abstract
IInVI quantum well structures containing a 2DEG of low density have been investigated by means of polarized photoluminescence, photoluminescence excitation and refl ectivity in external magnetic fi elds up to 20 T. The spin splittings of the excition X and the negatively charged exciton X are measured as a function of the magnetic fi eld strength. The behavior of the magnetic-fi eld-induced polarization degree of the luminescence line related to X demonstrates the formation process of negatively charged excitons from excitons and free carriers polarized by the external magnetic fi eld. We have determined the binding energies of the trion formed either with the heavy-hole or the light-hole exciton. The optically detected magnetic resonance (ODMR) technique was for the fi rst time applied to study the optical transition processes in a nanosecond timescale. The electron ODMR was observed with the detection on either the direct exciton or the negatively charged exciton X. Further evidence for the interaction of excitons with the electrons of the two dimensional gas are demonstrated by a combined exciton-cyclotron resonance line observed in refl ectivity and luminescence excitation, shake-up processes observed in photoluminescence as well as inelastic and spin-dependent scattering processes. Eects resulting from the exciton-electron interaction in the presence of a two-dimensional electron gas (2DEG) of low density at neaB 1, where ne is the electron concentration and aB is the exciton Bohr radius, became a subject of intensive investigations very recently. This interest has been stimulated by the observation of a negatively charged exciton X in CdTe/(Cd,Zn)Te modulation-doped quantum well (QW) structures [1]. In this paper we review several new eects observed in structures where the exciton interacts with a 2DEG of low carrier density. In detail we discuss: the spin splitting and polarization dependence of X and X in high magnetic fi eld [2]; the combined exciton-cyclotron resonance [3]; the optically detected magnetic resonance (ODMR) on X [4]; the shake-up process [5,6] and the spin-dependent broadening of excitonic states [7].
312. Elliptic emission of $K^+$ in 158A GeV Pb+Pb collisions
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P. Foka, Hr Schmidt, S. Dutt, David Olle Rickard Silvermyr, G. C. Mishra, Shunji Nishimura, I. Otterlund, E. Stenlund, A. Baldine, M. Kurata, T. H. Shah, R. Santo, M. D. Trivedi, MV Manzano Martin, B. W. Kolb, Y. Yokota, M. P. Decowski, Sanjeev Singh Sambyal, N.A. Kuzmin, L. Luquin, A. Maximov, D. Stüken, I. Langbein, Basanta Kumar Nandi, Sergey Nikolaev, S. Eliseev, I. Sibiriak, P. Kulinich, Nikolai V Slavine, Frank Jm Geurts, T. K. Nayak, G.S. Shabratova, A. Claussen, V. S. Ramamurthy, D. P. Mahapatra, J. Urbahn, Md. F. Mir, Ivana Hrivnacova, T. Krümpel, N. v. Eijndhoven, W. Pinanaud, V. Myalkovski, C. Blume, I. Roufanov, Hiroyuki Sako, D. Bucher, Petr Nomokonov, H. Kalechofsky, O. P. Gavrishchuk, B.N. Gus'kov, A. Agnihotri, A. A. Vinogradov, C. Roy, H. Naef, Rashmi Raniwala, A. Nianine, N. Solomey, S. Vörös, R. Higuchi, B. Batiounia, Yasuo Miake, Hyun-Chul Kim, E. C. v. d. Pijll, A.L.S. Angelis, Agneta Oskarsson, L. Rosselet, S. Pavliouk, S. Kees, V. Avdeitchikov, V. S. Bhatia, Mikhail Ippolitov, K. B. Bhalla, V. Djordjadze, Martin Purschke, Ashim Das, Klaus Johannes Reygers, K. Yagi, D. Mikhalev, P. Steinberg, S. K. Nayak, Sukalyan Chattopadhyay, M. S. Ganti, M. Pachr, Madan M. Aggarwal, Gunther Roland, R. Mehdiyev, H.H. Gutbrod, K. Kurita, K. El Chenawi, N. K. Rao, F. Retiere, K. Enosawa, S. Kato, P. W. Stankus, Susumu Sato, Herbert Löhner, C. Barlag, V. Chalyshev, Zubayer Ahammed, R. Glasow, R. Cherbatchev, S. K. Badyal, A.S. Vodopianov, A.L. Lebedev, Bikash Sinha, R. K. Bock, I. Koutcheryaev, F. E. Obenshain, P.V.K.S. Baba, P. Donni, Sudhir Raniwala, J. M. Rubio, L. Barabach, B. Raeven, S. Bathe, D. P. Morrison, F. Plasil, Tatsuya Chujo, A. A. Tsvetkov, Michal Sumbera, H. Büsching, Bolek Wyslouch, T. Peitzmann, A. Buijs, Y. Miyamoto, K. Söderström, Shiv K. Gupta, G. Mgebrichvili, D. S. Mukhopadhyay, L. Tykarski, I. Doubovik, Z.K. Böröcz, Vladislav Manko, Joakim Nystrand, E.-M. Bohne, S. P. Sorensen, A. Parfenov, G. R. Young, Peter M. Nilsson, Teodor Siemiarczuk, V.G. Antonenko, H. Schlagheck, I. Kosarev, T. K. Ghosh, Krzysztof Karpio, Jan Rak, Y. P. Viyogi, Vladimir Frolov, V. Petráček, Lars Carlén, G. Stefanek, V. Arefiev, T. C. Awes, Gerrit Jan van Nieuwenhuizen, K. Karadjev, Sergey Fokin, S. Garpman, H. A. Gustafsson, M. R. Dutta Majumdar, V. Astakhov, S. Neumaier, A. Kugler, R. Kamermans, T. Bernier, Kh Kampert, Y.Y. Lee, V. Nikitine, T. Svensson, Laboratoire SUBATECH Nantes (SUBATECH), Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and WA98
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Physics ,Nuclear reaction ,Nuclear and High Energy Physics ,Meson ,010308 nuclear & particles physics ,Nuclear Theory ,Hadron ,Elementary particle ,01 natural sciences ,7. Clean energy ,Charged particle ,Nuclear physics ,Baryon ,Pion ,[PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph] ,0103 physical sciences ,Atomic physics ,Nuclear Experiment ,010306 general physics ,Nucleon - Abstract
We have studied the azimuthal angle distributions of identified charged particles near mid-rapidity region in semi-central Pb+Pb collisions at SPS energies. Our preliminary results show that π+ mesons and protons seem to be emitted in the reaction plane, while out-of-plane for K+ mesons. This phenomenon might be explained by the existence of another possible effect such as in-medium potential as well as the collective motion.
313. Charged excitons in ZnSe-based quantum wells
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W. Faschinger, Dmitri R. Yakovlev, W. Ossau, G. Landwehr, V. P. Kochereshko, J. Nürnberger, and G. V. Astakhov
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Condensed Matter::Quantum Gases ,Physics ,Condensed Matter::Materials Science ,Condensed matter physics ,Condensed Matter::Other ,Exciton ,Binding energy ,Trion ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Polarization (waves) ,Biexciton ,Modulation doping ,Quantum well - Abstract
We report on magneto-optical studies of ZnSe/~Zn,Mg!~S,Se! quantum wells with n-type and p-type modulation doping. Negatively and positively charged excitons related to the heavy-hole exciton states are found and identified by their polarization properties. Negatively charged excitons formed with light-hole exciton states are observed. Their binding energy is about 20% less than that related to the heavy-hole exciton. The exciton and trion parameters ~radiative and nonradiative dampings! are determined. @S0163-1829~99!50136-7#
314. Erratum: Investigation of changes in the angular divergence of helium-neon laser radiation (λ = 3.39 μ) as a function of the dispersion characteristic of the active medium [Sov. J. Quantum Electron. 14, 1142-1143 (August 1984)]
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Yu V Gorlov, A V Astakhov, A F Mukhamedgalieva, and V V Nikitin
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Physics ,genetic structures ,business.industry ,General Engineering ,Self-focusing ,Electron ,Radiation ,Laser ,law.invention ,Optics ,law ,Dispersion (optics) ,sense organs ,Physics::Atomic Physics ,Atomic physics ,Divergence (statistics) ,business ,Quantum ,Refractive index - Abstract
The angular divergence of helium-neon laser radiation was found to depend on variation of the emission frequency within the limits of the gain profile of the active medium. The maximum relative change in the angular divergence was 4 ± 2%. This change appeared because of a nonlinear frequency dependence of the refractive index of the active medium in the region of the Doppler-broadened gain profile. The effect appeared particularly clear in the case of long optical paths.
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- 1984
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315. Investigation of changes in the angular divergence of helium-neon laser radiation (λ= 3.39μ) as a function of the dispersion characteristic of the active medium
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A F Mukhamedgalieva, V V Nikitin, A V Astakhov, and Yu V Gorlov
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Physics ,genetic structures ,business.industry ,General Engineering ,Function (mathematics) ,Radiation ,Laser ,Electromagnetic radiation ,law.invention ,Nonlinear system ,Optics ,law ,Dispersion (optics) ,sense organs ,Physics::Atomic Physics ,Atomic physics ,Divergence (statistics) ,business ,Refractive index - Abstract
The angular divergence of helium-neon laser radiation was found to depend on variation of the emission frequency within the limits of the gain profile of the active medium. The maximum relative change in the angular divergence was 4 ± 2%. This change appeared because of a nonlinear frequency dependence of the refractive index of the active medium in the region of the Doppler-broadened gain profile. The effect appeared particularly clear in the case of long optical paths.
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- 1984
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316. Creation of silicon vacancy in silicon carbide by proton beam writing toward quantum sensing applications.
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Takeshi Ohshima, Takahiro Satoh, Hannes Kraus, Georgy V Astakhov, Vladimir Dyakonov, and Pavel G Baranov
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SILICON carbide ,PROTON beams ,SPINTRONICS - Abstract
Single photon source (SPS) is a key element for quantum spintronics and quantum photonics. It is known that several color centers such as silicon vacancy (V
Si ), divacancy (VSi VC ), carbon antisite carbon vacancy pair (CSi VC ), in silicon carbide (SiC) act as SPSs. Spin (S = 3/2) in VSi in SiC can be manipulated even at room temperature and the intensity of its photoluminescence (PL) changes depending on the spin states (mS = ±3/2 or mS = ±1/2). Since PL from VSi is in the near infrared region (around 900 nm), it is expected that VSi is applied to quantum sensor especially for biological or medical applications. In this review, we discuss quantum sensing based on VSi in SiC. Also, we discuss energetic particle irradiation, especially proton beam writing (PBW), in which proton microbeams with MeV range are used, as a method to create VSi in SiC since PBW can create VSi in certain locations with micrometer accuracy and this is very useful to introduce VSi in electronic devices without the degradation of their electrical characteristics. [ABSTRACT FROM AUTHOR]- Published
- 2018
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317. Phase multistability of synchronous chaotic oscillations
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E. Vadivasova, T., V. Sosnovtseva, O., G. Balanov, A., and V. Astakhov, V.
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The paper describes the sequence of bifurcations leading to multistability of periodic and chaotic synchronous attractors for the coupled Rössler systems which individually demonstrate the Feigenbaum route to chaos. We investigate how a frequency mismatch affects this phenomenon. The role of a set of coexisting synchronous regimes in the transitions to and between different forms of synchronization is studied.
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- 2000
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318. INTERLEUKIN-6 PROFILE IN EARLY POSTOPERATIVE PERIOD AFTER KIDNEY TRANSPLANTATION
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A. V. Vatazin, A. B. Zulkarnaev, E. E. Kruglov, P. V. Astakhov, M. Krstic, K. K. Gubarev, I. A. Vasilenko, and D. V. Artemov
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ischemia ,reperfusion ,kidney transplantation ,cytokines ,interleukin-6 ,Surgery ,RD1-811 - Abstract
Aim. To study the profile of IL-6 in the early postoperative period after kidney transplantation and the factors that affect concentration of this cytokine. Methods and results. 28 kidney recipients were included in the study. It has been found that in most patients after surgery IL-6 was released, and the absence of such a reaction was a poor prognostic sign. Rate of increasing of the concentration and form of its curve within the first postoperative day depended on the length of preservation, warm ischemia time, type of donor, and differed in recipients with normal and delayed initial graft function. Conclusion. Further study of the role of circulating factors in kidney transplantation would improve patient outcomes.
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- 2013
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319. Deceleration of probe beam by stage bias potential improves resolution of serial block-face scanning electron microscopic images.
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Bouwer JC, Deerinck TJ, Bushong E, Astakhov V, Ramachandra R, Peltier ST, and Ellisman MH
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Serial block-face scanning electron microscopy (SBEM) is quickly becoming an important imaging tool to explore three-dimensional biological structure across spatial scales. At probe-beam-electron energies of 2.0 keV or lower, the axial resolution should improve, because there is less primary electron penetration into the block face. More specifically, at these lower energies, the interaction volume is much smaller, and therefore, surface detail is more highly resolved. However, the backscattered electron yield for metal contrast agents and the backscattered electron detector sensitivity are both sub-optimal at these lower energies, thus negating the gain in axial resolution. We found that the application of a negative voltage (reversal potential) applied to a modified SBEM stage creates a tunable electric field at the sample. This field can be used to decrease the probe-beam-landing energy and, at the same time, alter the trajectory of the signal to increase the signal collected by the detector. With decelerated low landing-energy electrons, we observed that the probe-beam-electron-penetration depth was reduced to less than 30 nm in epoxy-embedded biological specimens. Concurrently, a large increase in recorded signal occurred due to the re-acceleration of BSEs in the bias field towards the objective pole piece where the detector is located. By tuning the bias field, we were able to manipulate the trajectories of the primary and secondary electrons, enabling the spatial discrimination of these signals using an advanced ring-type BSE detector configuration or a standard monolithic BSE detector coupled with a blocking aperture.
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- 2017
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320. Early experiences in developing and managing the neuroscience gateway.
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Sivagnanam S, Majumdar A, Yoshimoto K, Astakhov V, Bandrowski A, Martone M, and Carnevale NT
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The last few decades have seen the emergence of computational neuroscience as a mature field where researchers are interested in modeling complex and large neuronal systems and require access to high performance computing machines and associated cyber infrastructure to manage computational workflow and data. The neuronal simulation tools, used in this research field, are also implemented for parallel computers and suitable for high performance computing machines. But using these tools on complex high performance computing machines remains a challenge because of issues with acquiring computer time on these machines located at national supercomputer centers, dealing with complex user interface of these machines, dealing with data management and retrieval. The Neuroscience Gateway is being developed to alleviate and/or hide these barriers to entry for computational neuroscientists. It hides or eliminates, from the point of view of the users, all the administrative and technical barriers and makes parallel neuronal simulation tools easily available and accessible on complex high performance computing machines. It handles the running of jobs and data management and retrieval. This paper shares the early experiences in bringing up this gateway and describes the software architecture it is based on, how it is implemented, and how users can use this for computational neuroscience research using high performance computing at the back end. We also look at parallel scaling of some publicly available neuronal models and analyze the recent usage data of the neuroscience gateway.
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- 2015
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321. A hybrid human and machine resource curation pipeline for the Neuroscience Information Framework.
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Bandrowski AE, Cachat J, Li Y, Müller HM, Sternberg PW, Ciccarese P, Clark T, Marenco L, Wang R, Astakhov V, Grethe JS, and Martone ME
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- Abstracting and Indexing, Computational Biology, Humans, Software, Database Management Systems, Databases, Factual classification, Neurosciences methods
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The breadth of information resources available to researchers on the Internet continues to expand, particularly in light of recently implemented data-sharing policies required by funding agencies. However, the nature of dense, multifaceted neuroscience data and the design of contemporary search engine systems makes efficient, reliable and relevant discovery of such information a significant challenge. This challenge is specifically pertinent for online databases, whose dynamic content is 'hidden' from search engines. The Neuroscience Information Framework (NIF; http://www.neuinfo.org) was funded by the NIH Blueprint for Neuroscience Research to address the problem of finding and utilizing neuroscience-relevant resources such as software tools, data sets, experimental animals and antibodies across the Internet. From the outset, NIF sought to provide an accounting of available resources, whereas developing technical solutions to finding, accessing and utilizing them. The curators therefore, are tasked with identifying and registering resources, examining data, writing configuration files to index and display data and keeping the contents current. In the initial phases of the project, all aspects of the registration and curation processes were manual. However, as the number of resources grew, manual curation became impractical. This report describes our experiences and successes with developing automated resource discovery and semiautomated type characterization with text-mining scripts that facilitate curation team efforts to discover, integrate and display new content. We also describe the DISCO framework, a suite of automated web services that significantly reduce manual curation efforts to periodically check for resource updates. Lastly, we discuss DOMEO, a semi-automated annotation tool that improves the discovery and curation of resources that are not necessarily website-based (i.e. reagents, software tools). Although the ultimate goal of automation was to reduce the workload of the curators, it has resulted in valuable analytic by-products that address accessibility, use and citation of resources that can now be shared with resource owners and the larger scientific community. DATABASE URL: http://neuinfo.org.
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- 2012
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322. A survey of the neuroscience resource landscape: perspectives from the neuroscience information framework.
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Cachat J, Bandrowski A, Grethe JS, Gupta A, Astakhov V, Imam F, Larson SD, and Martone ME
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- Animals, Humans, Computational Biology, Databases as Topic, Information Storage and Retrieval, Neurosciences
- Abstract
The number of available neuroscience resources (databases, tools, materials, and networks) available via the Web continues to expand, particularly in light of newly implemented data sharing policies required by funding agencies and journals. However, the nature of dense, multifaceted neuroscience data and the design of classic search engine systems make efficient, reliable, and relevant discovery of such resources a significant challenge. This challenge is especially pertinent for online databases, whose dynamic content is largely opaque to contemporary search engines. The Neuroscience Information Framework was initiated to address this problem of finding and utilizing neuroscience-relevant resources. Since its first production release in 2008, NIF has been surveying the resource landscape for the neurosciences, identifying relevant resources and working to make them easily discoverable by the neuroscience community. In this chapter, we provide a survey of the resource landscape for neuroscience: what types of resources are available, how many there are, what they contain, and most importantly, ways in which these resources can be utilized by the research community to advance neuroscience research., (Copyright © 2012 Elsevier Inc. All rights reserved.)
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- 2012
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323. Prototype of Kepler Processing Workflows For Microscopy And Neuroinformatics.
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Astakhov V, Bandrowski A, Gupta A, Kulungowski AW, Grethe JS, Bouwer J, Molina T, Rowley V, Penticoff S, Terada M, Wong W, Hakozaki H, Kwon O, Martone ME, and Ellisman M
- Abstract
We report on progress of employing the Kepler workflow engine to prototype "end-to-end" application integration workflows that concern data coming from microscopes deployed at the National Center for Microscopy Imaging Research (NCMIR). This system is built upon the mature code base of the Cell Centered Database (CCDB) and integrated rule-oriented data system (IRODS) for distributed storage. It provides integration with external projects such as the Whole Brain Catalog (WBC) and Neuroscience Information Framework (NIF), which benefit from NCMIR data. We also report on specific workflows which spawn from main workflows and perform data fusion and orchestration of Web services specific for the NIF project. This "Brain data flow" presents a user with categorized information about sources that have information on various brain regions.
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- 2012
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324. Vaginal progesterone reduces the rate of preterm birth in women with a sonographic short cervix: a multicenter, randomized, double-blind, placebo-controlled trial.
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Hassan SS, Romero R, Vidyadhari D, Fusey S, Baxter JK, Khandelwal M, Vijayaraghavan J, Trivedi Y, Soma-Pillay P, Sambarey P, Dayal A, Potapov V, O'Brien J, Astakhov V, Yuzko O, Kinzler W, Dattel B, Sehdev H, Mazheika L, Manchulenko D, Gervasi MT, Sullivan L, Conde-Agudelo A, Phillips JA, and Creasy GW
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- Administration, Intravaginal, Adolescent, Adult, Cervix Uteri diagnostic imaging, Double-Blind Method, Female, Humans, Placebos, Pregnancy, Pregnancy Outcome, Pregnancy, High-Risk, Prospective Studies, Ultrasonography, Vagina diagnostic imaging, Vagina drug effects, Vaginal Creams, Foams, and Jellies administration & dosage, Young Adult, Cervix Uteri drug effects, Premature Birth drug therapy, Premature Birth prevention & control, Progesterone administration & dosage, Progestins administration & dosage
- Abstract
Objectives: Women with a sonographic short cervix in the mid-trimester are at increased risk for preterm delivery. This study was undertaken to determine the efficacy and safety of using micronized vaginal progesterone gel to reduce the risk of preterm birth and associated neonatal complications in women with a sonographic short cervix., Methods: This was a multicenter, randomized, double-blind, placebo-controlled trial that enrolled asymptomatic women with a singleton pregnancy and a sonographic short cervix (10-20 mm) at 19 + 0 to 23 + 6 weeks of gestation. Women were allocated randomly to receive vaginal progesterone gel or placebo daily starting from 20 to 23 + 6 weeks until 36 + 6 weeks, rupture of membranes or delivery, whichever occurred first. Randomization sequence was stratified by center and history of a previous preterm birth. The primary endpoint was preterm birth before 33 weeks of gestation. Analysis was by intention to treat., Results: Of 465 women randomized, seven were lost to follow-up and 458 (vaginal progesterone gel, n=235; placebo, n=223) were included in the analysis. Women allocated to receive vaginal progesterone had a lower rate of preterm birth before 33 weeks than did those allocated to placebo (8.9% (n=21) vs 16.1% (n=36); relative risk (RR), 0.55; 95% CI, 0.33-0.92; P=0.02). The effect remained significant after adjustment for covariables (adjusted RR, 0.52; 95% CI, 0.31-0.91; P=0.02). Vaginal progesterone was also associated with a significant reduction in the rate of preterm birth before 28 weeks (5.1% vs 10.3%; RR, 0.50; 95% CI, 0.25-0.97; P=0.04) and 35 weeks (14.5% vs 23.3%; RR, 0.62; 95% CI, 0.42-0.92; P=0.02), respiratory distress syndrome (3.0% vs 7.6%; RR, 0.39; 95% CI, 0.17-0.92; P=0.03), any neonatal morbidity or mortality event (7.7% vs 13.5%; RR, 0.57; 95% CI, 0.33-0.99; P=0.04) and birth weight < 1500 g (6.4% (15/234) vs 13.6% (30/220); RR, 0.47; 95% CI, 0.26-0.85; P=0.01). There were no differences in the incidence of treatment-related adverse events between the groups., Conclusions: The administration of vaginal progesterone gel to women with a sonographic short cervix in the mid-trimester is associated with a 45% reduction in the rate of preterm birth before 33 weeks of gestation and with improved neonatal outcome., (Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.)
- Published
- 2011
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325. Peculiarities of the transitions to synchronization in coupled systems with amplitude death.
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Astakhov V, Koblyanskii S, Shabunin A, and Kapitaniak T
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The paper presents the results of the study of the sequences of bifurcation leading to the synchronization and amplitude death in a system of two dissipatively coupled self-sustained oscillators with inertial nonlinearity. Two types of synchronizations tongues have been identified. In one of them phase locking regions exist where the synchronization is achieved by the saddle-node bifurcation and regions where the transition to synchronization leads through Neimark-Sacker bifurcation. In the second type of the tongues there are only phase locking regions. It has been shown that for a weak non-identity of the system parameters, the first type tongues merge together. The transition between the synchronization tongues can occur without bifurcations, i.e., transition between the synchronized regimes with different periods of oscillations can occur gradually.
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- 2011
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326. Phase multistability and phase synchronization in an array of locally coupled period-doubling oscillators.
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Shabunin A, Feudel U, and Astakhov V
- Abstract
We consider phase multistability and phase synchronization phenomena in a chain of period-doubling oscillators. The synchronization in arrays of diffusively coupled self-sustained oscillators manifests itself as rotating wave regimes, which are characterized by equal amplitudes and phases in every site which are shifted by a constant value. The value of the phase shift is preserved while the shape of motion becomes more complex through a period-doubling cascade. The number of coexisting attractors increases drastically after the transition from period-one to period-two oscillations and then after every following period-doubling bifurcation. In the chaotic region, we observe a number of phase-synchronized modes with instantaneous phases locked in different values. The loss of phase synchronization with decreasing coupling is accompanied by intermittency between several synchronous regimes.
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- 2009
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327. Mediator infrastructure for information integration and semantic data integration environment for biomedical research.
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Grethe JS, Ross E, Little D, Sanders B, Gupta A, and Astakhov V
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- Algorithms, Computer Communication Networks, Computer Systems, Internet, National Institutes of Health (U.S.), Programming Languages, United States, User-Computer Interface, Computational Biology, Database Management Systems, Databases, Factual, Information Storage and Retrieval
- Abstract
This paper presents current progress in the development of semantic data integration environment which is a part of the Biomedical Informatics Research Network (BIRN; http://www.nbirn.net) project. BIRN is sponsored by the National Center for Research Resources (NCRR), a component of the National Institutes of Health (NIH). A goal is the development of a cyberinfrastructure for biomedical research that supports advance data acquisition, data storage, data management, data integration, data mining, data visualization, and other computing and information processing services over the Internet. Each participating institution maintains storage of their experimental or computationally derived data. Mediator-based data integration system performs semantic integration over the databases to enable researchers to perform analyses based on larger and broader datasets than would be available from any single institution's data. This paper describes recent revision of the system architecture, implementation, and capabilities of the semantically based data integration environment for BIRN.
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- 2009
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328. Biomedical informatics. Preface.
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Astakhov V
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- Computational Biology trends, Computational Biology methods
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- 2009
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329. Methods of information geometry in computational system biology (consistency between chemical and biological evolution).
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Astakhov V
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- Metabolic Networks and Pathways, Models, Biological, Biological Evolution, Computational Biology, Systems Biology
- Abstract
Interest in simulation of large-scale metabolic networks, species development, and genesis of various diseases requires new simulation techniques to accommodate the high complexity of realistic biological networks. Information geometry and topological formalisms are proposed to analyze information processes. We analyze the complexity of large-scale biological networks as well as transition of the system functionality due to modification in the system architecture, system environment, and system components. The dynamic core model is developed. The term dynamic core is used to define a set of causally related network functions. Delocalization of dynamic core model provides a mathematical formalism to analyze migration of specific functions in biosystems which undergo structure transition induced by the environment. The term delocalization is used to describe these processes of migration. We constructed a holographic model with self-poetic dynamic cores which preserves functional properties under those transitions. Topological constraints such as Ricci flow and Pfaff dimension were found for statistical manifolds which represent biological networks. These constraints can provide insight on processes of degeneration and recovery which take place in large-scale networks. We would like to suggest that therapies which are able to effectively implement estimated constraints, will successfully adjust biological systems and recover altered functionality. Also, we mathematically formulate the hypothesis that there is a direct consistency between biological and chemical evolution. Any set of causal relations within a biological network has its dual reimplementation in the chemistry of the system environment.
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- 2009
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330. Brain model of text animation as a data mining strategy.
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Astakhova T and Astakhov V
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- Brain physiology, Holography, Humans, Memory, Models, Neurological, Models, Psychological, Nerve Net physiology, Reading, Visual Perception, Artificial Intelligence, Computational Biology, Imagination
- Abstract
Imagination is the critical point in developing of realistic intelligence (AI) systems. One way to approach imagination would be simulation of its properties and operations. We developed two models "Brain Network Hierarchy of Languages," and "Semantical Holographic Calculus" and simulation system ScriptWriter that emulate the process of imagination through an automatic animation of English texts. The purpose of this paper is to demonstrate the model and present "ScriptWriter" system http://nvo.sdsc.edu/NVO/JCSG/get_SRB_mime_file2.cgi//home/tamara.sdsc/test/demo.zip?F=/home/tamara.sdsc/test/demo.zip&M=application/x-gtar for simulation of the imagination.
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- 2009
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331. Federated access to heterogeneous information resources in the Neuroscience Information Framework (NIF).
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Gupta A, Bug W, Marenco L, Qian X, Condit C, Rangarajan A, Müller HM, Miller PL, Sanders B, Grethe JS, Astakhov V, Shepherd G, Sternberg PW, and Martone ME
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- Access to Information, Animals, Computational Biology trends, Humans, Information Storage and Retrieval methods, Information Storage and Retrieval trends, Internet organization & administration, Internet trends, Meta-Analysis as Topic, Neurosciences standards, Software standards, Software trends, Computational Biology methods, Databases as Topic trends, Neurosciences methods
- Abstract
The overarching goal of the NIF (Neuroscience Information Framework) project is to be a one-stop-shop for Neuroscience. This paper provides a technical overview of how the system is designed. The technical goal of the first version of the NIF system was to develop an information system that a neuroscientist can use to locate relevant information from a wide variety of information sources by simple keyword queries. Although the user would provide only keywords to retrieve information, the NIF system is designed to treat them as concepts whose meanings are interpreted by the system. Thus, a search for term should find a record containing synonyms of the term. The system is targeted to find information from web pages, publications, databases, web sites built upon databases, XML documents and any other modality in which such information may be published. We have designed a system to achieve this functionality. A central element in the system is an ontology called NIFSTD (for NIF Standard) constructed by amalgamating a number of known and newly developed ontologies. NIFSTD is used by our ontology management module, called OntoQuest to perform ontology-based search over data sources. The NIF architecture currently provides three different mechanisms for searching heterogeneous data sources including relational databases, web sites, XML documents and full text of publications. Version 1.0 of the NIF system is currently in beta test and may be accessed through http://nif.nih.gov.
- Published
- 2008
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332. Suppression of high-p{T} neutral pion production in central Pb+Pb collisions at sqrt[S{NN}]=17.3 GeV relative to p+C and p+Pb collisions.
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Aggarwal MM, Ahammed Z, Angelis AL, Antonenko V, Arefiev V, Astakhov V, Avdeitchikov V, Awes TC, Baba PV, Badyal SK, Bathe S, Batiounia B, Baumann C, Bernier T, Bhalla KB, Bhatia VS, Blume C, Bucher D, Büsching H, Carlén L, Chattopadhyay S, Decowski MP, Delagrange H, Donni P, Majumdar MR, El Chenawi K, Dubey AK, Enosawa K, Fokin S, Frolov V, Ganti MS, Garpman S, Gavrishchuk O, Geurts FJ, Ghosh TK, Glasow R, Guskov B, Gustafsson HA, Gutbrod HH, Hrivnacova I, Ippolitov M, Kalechofsky H, Kamermans R, Karadjev K, Karpio K, Kolb BW, Kosarev I, Koutcheryaev I, Kugler A, Kulinich P, Kurata M, Lebedev A, Löhner H, Luquin L, Mahapatra DP, Manko V, Martin M, Martínez G, Maximov A, Miake Y, Mishra GC, Mohanty B, Mora MJ, Morrison D, Mukhanova T, Mukhopadhyay DS, Naef H, Nandi BK, Nayak SK, Nayak TK, Nianine A, Nikitine V, Nikolaev S, Nilsson P, Nishimura S, Nomokonov P, Nystrand J, Oskarsson A, Otterlund I, Pavliouk S, Peitzmann T, Peressounko D, Petracek V, Phatak SC, Pinganaud W, Plasil F, Purschke ML, Rak J, Rammler M, Raniwala R, Raniwala S, Rao NK, Retiere F, Reygers K, Roland G, Rosselet L, Roufanov I, Roy C, Rubio JM, Sambyal SS, Santo R, Sato S, Schlagheck H, Schmidt HR, Schutz Y, Shabratova G, Shah TH, Sibiriak I, Siemiarczuk T, Silvermyr D, Sinha BC, Slavine N, Söderström K, Sood G, Sørensen SP, Stankus P, Stefanek G, Steinberg P, Stenlund E, Sumbera M, Svensson T, Tsvetkov A, Tykarski L, V D Pijll EC, V Eijndhoven N, V Nieuwenhuizen GJ, Vinogradov A, Viyogi YP, Vodopianov A, Vörös S, Wysłouch B, and Young GR
- Abstract
Neutral pion transverse momentum spectra were measured in p+C and p+Pb collisions at sqrt[S{NN}]=17.4 GeV at midrapidity (2.3 less than or approximately equal eta{lab} less than or approximately equal 3.0) over the range 0.7 less than or approximately equal p{T} less than or approximately equal 3.5 GeV/c. The spectra are compared to pi{0} spectra measured in Pb+Pb collisions at sqrt[S{NN}]=17.3 GeV in the same experiment. For a wide range of Pb+Pb centralities (N{part} less than or approximately equal 300), the yield of pi{0}'s with p{T} greater than or approximately equal 2 GeV/c is larger than or consistent with the p+C or p+Pb yields scaled with the number of nucleon-nucleon collisions (N{coll}), while for central Pb+Pb collisions with N{part}greater than or approximately equal 350, the pi{0} yield is suppressed.
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- 2008
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333. Prediction of HLA-A2 binding peptides using Bayesian network.
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Astakhov V and Cherkasov A
- Abstract
Prediction of peptides binding to HLA (human leukocyte antigen) finds application in peptide vaccine design. A number of statistical and structural models have been developed in recent years for HLA binding peptide prediction. However, a Bayesian Network (BNT) model is not available. In this study we describe a BNT model for HLA-A2 binding peptide prediction. It has been demonstrated that the BNT model allows up to 99 % accurate identification of the HLA-A2 binding peptides and provides similar prediction accuracy compared to HMM (Hidden Markov Model) and ANN (Artificial Neural Network). At the same time, it has been shown that the BNT has that advantage that it allows more accurate performance for smaller sets of empirical data compared to the HMM and the ANN methods. When the size of the training set has been reduced to 40% from the original data, the identification of the HLA-A2 binding peptides by the BNT, ANN and HMM methods produced ARoc (area under receiver operating characteristic) values 0.88, 0.85, 0.85 respectively. The results of the work demonstrate certain advantages of using the Bayesian Networks in predicting the HLA binding peptides using smaller datasets.
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- 2005
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334. Quantitative analysis of chaotic synchronization by means of coherence.
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Shabunin A, Astakhov V, and Kurths J
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We use an index of chaotic synchronization based on the averaged coherence function for the quantitative analysis of the process of the complete synchronization loss in unidirectionally coupled oscillators and maps. We demonstrate that this value manifests different stages of the synchronization breaking. It is invariant to time delay and insensitive to small noise and distortions, which can influence the accessible signals at measurements. Peculiarities of the synchronization destruction in maps and oscillators are investigated.
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- 2005
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335. Interferometry of direct photons in central 208Pb + 208Pb collisions at 158A GeV.
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Aggarwal MM, Ahammed Z, Angelis AL, Antonenko V, Arefiev V, Astakhov V, Avdeitchikov V, Awes TC, Baba PV, Badyal SK, Bathe S, Batiounia B, Bernier T, Bhalla KB, Bhatia VS, Blume C, Bucher D, Büsching H, Carlén L, Chattopadhyay S, Decowski MP, Delagrange H, Donni P, Dutta Majumdar MR, el Chenawi K, Dubey AK, Enosawa K, Fokin S, Frolov V, Ganti MS, Garpman S, Gavrishchuk O, Geurts FJ, Ghosh TK, Glasow R, Guskov B, Gustafsson HA, Gutbrod HH, Hrivnacova I, Ippolitov M, Kalechofsky H, Karadjev K, Karpio K, Kolb BW, Kosarev I, Koutcheryaev I, Kugler A, Kulinich P, Kurata M, Lebedev A, Löhner H, Luquin L, Mahapatra DP, Manko V, Martin M, Martínez G, Maximov A, Miake Y, Mishra GC, Mohanty B, Mora MJ, Morrison D, Moukhanova T, Mukhopadhyay DS, Naef H, Nandi BK, Nayak SK, Nayak TK, Nianine A, Nikitine V, Nikolaev S, Nilsson P, Nishimura S, Nomokonov P, Nystrand J, Oskarsson A, Otterlund I, Peitzmann T, Peressounko D, Petracek V, Phatak SC, Pinganaud W, Plasil F, Purschke ML, Rak J, Raniwala R, Raniwala S, Rao NK, Retiere F, Reygers K, Roland G, Rosselet L, Roufanov I, Roy C, Rubio JM, Sambyal SS, Santo R, Sato S, Schlagheck H, Schmidt HR, Schutz Y, Shabratova G, Shah TH, Sibiriak I, Siemiarczuk T, Silvermyr D, Sinha BC, Slavine N, Söderström K, Sood G, Sørensen SP, Stankus P, Stefanek G, Steinberg P, Stenlund E, Sumbera M, Svensson T, Tsvetkov A, Tykarski L, v d Pijll EC, von Eijndhoven N, von Nieuwenhuizen GJ, Vinogradov A, Viyogi YP, Vodopianov A, Vörös S, Wysłouch B, and Young GR
- Abstract
Two-particle correlations of direct photons were measured in central 208Pb+208Pb collisions at 158A GeV. The invariant interferometric radii were extracted for 100
- Published
- 2004
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336. Information theoretic approach to quantify complete and phase synchronization of chaos.
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Shabunin A, Demidov V, Astakhov V, and Anishchenko V
- Abstract
Based on an information theory approach we suggest a quantitative characteristic for evaluating the degree of chaotic synchronization. The proposed characteristic is tested for the cases of complete and phase synchronization of chaos. It is shown that this characteristic is stable with respect to the influence of small noise and nonlinear signal distortion.
- Published
- 2002
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337. Multistability formation and synchronization loss in coupled Hénon maps: two sides of the single bifurcational mechanism.
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Astakhov V, Shabunin A, Uhm W, and Kim S
- Abstract
We investigate phenomena of multistability and complete chaos synchronization in coupled Hénon maps, which is an invertible system. Multiparametric analysis of a selected family of periodic orbits for coupled Henon maps shows that a single bifurcational mechanism describes both a loss of chaos synchronization and multistability formation. The process of bubbling transition and riddle basins, and the multistability formation in invertible systems are described in detail.
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- 2001
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338. Three-pion interferometry results from central Pb+Pb collisions at 158A GeV/c.
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Aggarwal MM, Agnihotri A, Ahammed Z, Angelis AL, Antonenko V, Arefiev V, Astakhov V, Avdeitchikov V, Awes TC, Baba PV, Badyal SK, Barlag C, Bathe S, Batiounia B, Bernier T, Bhalla KB, Bhatia VS, Blume C, Bock R, Bohne EM, Böröcz Z, Bucher D, Buijs A, Büsching H, Carlen L, Chalyshev V, Chattopadhyay S, Cherbatchev R, Chujo T, Claussen A, Das AC, Decowski MP, Delagrange H, Djordjadze V, Donni P, Doubovik I, Dutt S, Dutta Majumdar MR, El Chenawi K, Eliseev S, Enosawa K, Foka P, Fokin S, Ganti MS, Garpman S, Gavrishchuk O, Geurts FJ, Ghosh TK, Glasow R, Gupta SK, Guskov B, Gustafsson HA, Gutbrod HH, Higuchi R, Hrivnacova I, Ippolitov M, Kalechofsky H, Kamermans R, Kampert KH, Karadjev K, Karpio K, Kato S, Kees S, Klein-Bösing C, Knoche S, Kolb BW, Kosarev I, Koutcheryaev I, Krümpel T, Kugler A, Kulinich P, Kurata M, Kurita K, Kuzmin N, Langbein I, Lebedev A, Lee YY, Löhner H, Luquin L, Mahapatra DP, Manko V, Martin M, Martínez G, Maximov A, Mgebrichvili G, Miake Y, Mir MF, Mishra GC, Miyamoto Y, Mohanty B, Mora MJ, Morrison D, Mukhopadhyay DS, Naef H, Nandi BK, Nayak SK, Nayak TK, Neumaier S, Nianine A, Nikitine V, Nikolaev S, Nilsson P, Nishimura S, Nomokonov P, Nystrand J, Obenshain FE, Oskarsson A, Otterlund I, Pachr M, Pavliouk S, Peitzmann T, Petracek V, Pinganaud W, Plasil F, von Poblotzki U, Purschke ML, Rak J, Raniwala R, Raniwala S, Ramamurthy VS, Rao NK, Retiere F, Reygers K, Roland G, Rosselet L, Roufanov I, Roy C, Rubio JM, Sako H, Sambyal SS, Santo R, Sato S, Schlagheck H, Schmidt HR, Schutz Y, Shabratova G, Shah TH, Sibiriak I, Siemiarczuk T, Silvermyr D, Sinha BC, Slavine N, Söderström K, Solomey N, Sørensen SP, Stankus P, Stefanek G, Steinberg P, Stenlund E, Stüken D, Sumbera M, Svensson T, Trivedi MD, Tsvetkov A, Tykarski L, Urbahn J, Pijll EC, Eijndhoven N, Nieuwenhuizen GJ, Vinogradov A, Viyogi YP, Vodopianov A, Vörös S, Wysłouch B, Yagi K, Yokota Y, and Young GR
- Abstract
Three-particle correlations have been measured for identified pi(-) from central 158A GeV Pb+Pb collisions by the WA98 experiment at CERN. A substantial contribution of the genuine three-body correlation has been found as expected for a mainly chaotic and symmetric source.
- Published
- 2000
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