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Search Results: 1 - 10 of 400822 matches for " M. Golubeva "
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Laser photon statistics in the feedback loop
T. Yu. Golubeva,Yu. M. Golubev
Physics , 2005,
Abstract: A mere correspondence between the electron statistics and the photon one vanishes in the feedback loop (FBL). It means that the direct photodetection, supplying us with the electron statistics, does not provide us with a wished information about the laser photon statistics. For getting this information we should think up another measurement procedure, and we in the article suggest applying the three-level laser as a auxiliary measuring device. This laser has impressive property, namely, its photon statistics survive information about the initial photon statistics of the laser which excites coherently the three-level medium. Thus, if we choose the laser in the FBL as exciting the three-level laser, then we have an possibility to evaluate its initial photon statistics by means of direct detecting the three-level laser emission. Finally, this approach allows us to conclude the feedback is not capable of creating a regularity in the laser light beam. Contrary, the final photon fluctuations turn out to be always even bigger. The mentioned above feature of the three-level laser takes place only for the strong interaction between the lasers (exciting and excited). It means the initial state of the exciting laser is changed dramatically, so our measurement procedure can not be identified with some non-demolition one.
Optimizing Frozen Sample Preparation for Laser Microdissection: Assessment of CryoJane Tape-Transfer System?
Yelena G. Golubeva, Roberta M. Smith, Lawrence R. Sternberg
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0066854
Abstract: Laser microdissection is an invaluable tool in medical research that facilitates collecting specific cell populations for molecular analysis. Diversity of research targets (e.g., cancerous and precancerous lesions in clinical and animal research, cell pellets, rodent embryos, etc.) and varied scientific objectives, however, present challenges toward establishing standard laser microdissection protocols. Sample preparation is crucial for quality RNA, DNA and protein retrieval, where it often determines the feasibility of a laser microdissection project. The majority of microdissection studies in clinical and animal model research are conducted on frozen tissues containing native nucleic acids, unmodified by fixation. However, the variable morphological quality of frozen sections from tissues containing fat, collagen or delicate cell structures can limit or prevent successful harvest of the desired cell population via laser dissection. The CryoJane Tape-Transfer System?, a commercial device that improves cryosectioning outcomes on glass slides has been reported superior for slide preparation and isolation of high quality osteocyte RNA (frozen bone) during laser dissection. Considering the reported advantages of CryoJane for laser dissection on glass slides, we asked whether the system could also work with the plastic membrane slides used by UV laser based microdissection instruments, as these are better suited for collection of larger target areas. In an attempt to optimize laser microdissection slide preparation for tissues of different RNA stability and cryosectioning difficulty, we evaluated the CryoJane system for use with both glass (laser capture microdissection) and membrane (laser cutting microdissection) slides. We have established a sample preparation protocol for glass and membrane slides including manual coating of membrane slides with CryoJane solutions, cryosectioning, slide staining and dissection procedure, lysis and RNA extraction that facilitated efficient dissection and high quality RNA retrieval from CryoJane preparations. CryoJane technology therefore has the potential to facilitate standardization of laser microdissection slide preparation from frozen tissues.
Omega- and Phi-meson production in pn -> dV reactions and OZI-rule violation
L. A. Kondratyuk,Ye. S. Golubeva,M. Buescher
Physics , 1998,
Abstract: We investigate the reactions p n -> d omega and p n -> d phi close to threshold and at higher energies. Near threshold we calculate the S-wave amplitudes within the framework of the two-step model which is described by a triangle graph with pi-mesons in the intermediate state and find a ratio of the S-wave amplitudes squared of R =|A(phi)|^2/|A(omega)|^2 = (4-8) x 10^{-3}. Any significant enhancement of the experimental value of R(phi/omega) over this prediction can be interpreted as a possible contribution of the intrinsic s - anti s component in the nucleon-wave function. We present arguments that there is a strong resonance effect in the omega N channel close to threshold. At higher energies we calculate the differential cross sections of the reactions p n -> d omega, p n -> d phi and the ratio of the phi/omega yields within the framework of the quark-gluon string model. An irregular behavior of the phi/omega-ratio is found at s <= 12 GeV^2 due to the interference of the t- and u-channel contributions.
Polarization statistical properties of the emission from the single mode Vertical-Cavity Surface-Emitting Lasers with the equally living laser levels
Yu. M. Golubev,T. Yu. Golubeva,E. Giacobino
Physics , 2004, DOI: 10.1088/1464-4266/6/12/007
Abstract: The full quantum-statistical theory of the Vertical-Cavity Surface-Emitting Laser (VCSEL) in the form of the Langevin equations is constructed for arbitrary relations between the frequency parameters. The same theoretical treatment as in Ref.[1,2] are used. For detailed analysis the theory is applied for lasers with equally living laser levels and on this basis the analytical expressions for the spectral densities of the Stokes parameter fluctuations are obtained in the explicit dependence on the physical phenomena, including the spin-flip and the optical anisotropy. It is demonstrated the arbitrary distribution of electrons between the sub-levels under pumping does not restrict a possibility to achieve the noise reduction below the quantum limit. Under comparison with phenomenological treatment Ref.[3] it is shown this approach turns out to be not quite satisfied.
Features of physiological status of aged people in sparsely circumpolar areas of Russia  [PDF]
Elena Yu. Golubeva, Raisa I. Danilova
Health (Health) , 2012, DOI: 10.4236/health.2012.429116
Abstract: Stable growth of the elderly age group is observed in the population of circumpolar areas of Russia. In northern conditions chronic pathology facilitates activity restriction development, changing the habitual lifestyle. Ageing process involves functional constraints of physical and mental activities, difficulties in doing everyday work. Aging changes of the nervous and respiratory systems are more characteristic of aged men and women living in the nursing home system of Russian urban circumpolar area. These changes are caused by worse psychological state, hypokinesia so there is a need in improving approaches in medical and social care services, in particular, introducing activating technologies and the micro-environment enhancement.
Polarization squeezing in vertical-cavity surface-emitting lasers
Yu. M. Golubev,T. Yu. Golubeva,M. I. Kolobov,E. Giacobino
Physics , 2004, DOI: 10.1103/PhysRevA.70.053817
Abstract: We further elaborate the theory of quantum fluctuations in vertical-cavity surface-emitting lasers (VCSELs), developed in Ref. \cite{Hermier02}. In particular, we introduce the quantum Stokes parameters to describe the quantum self- and cross-correlations between two polarization components of the electromagnetic field generated by this type of lasers. We calculate analytically the fluctuation spectra of these parameters and discuss experiments in which they can be measured. We demonstrate that in certain situations VCSELs can exhibit polarization squeezing over some range of spectral frequencies. This polarization squeezing has its origin in sub-Poissonian pumping statistics of the active laser medium.
Controlling a group velocity of light by magnetic field
Yu. M. Golubev,T. Yu. Golubeva,Yu. V. Rostovtsev,M. O. Scully
Physics , 2004,
Abstract: We have shown that quantum interference in a driven quasi-degenerate two-level atomic system can be controlled by an externally applied magnetic field. We demonstrate that the mechanism of optical control is based on quantum interference, which allows one to implement both electromagnetically induced transparency and electromagnetically induced absorption in one atomic system. Dispersion of such the medium allows one to control group velocity of propagation of light pulses be ultra-slow or superluminal via applied magnetic field.
Quantum parallel dense coding of optical images
T. Yu. Golubeva,Yu. M. Golubev,I. V. Sokolov,M. I. Kolobov
Physics , 2005, DOI: 10.1080/09500340500217506
Abstract: We propose quantum dense coding protocol for optical images. This protocol extends the earlier proposed dense coding scheme for continuous variables [S.L.Braunstein and H.J.Kimble, Phys.Rev.A 61, 042302 (2000)] to an essentially multimode in space and time optical quantum communication channel. This new scheme allows, in particular, for parallel dense coding of non-stationary optical images. Similar to some other quantum dense coding protocols, our scheme exploits the possibility of sending a classical message through only one of the two entangled spatially-multimode beams, using the other one as a reference system. We evaluate the Shannon mutual information for our protocol and find that it is superior to the standard quantum limit. Finally, we show how to optimize the performance of our scheme as a function of the spatio-temporal parameters of the multimode entangled light and of the input images.
Density dependence of resonance broadening and shadowing effects in nuclear photoabsorption
S. Boffi,Ye. Golubeva,L. A. Kondratyuk,M. I. Krivoruchenko,E. Perazzi
Physics , 1996,
Abstract: Medium effects as a function of the mass number $A$ are studied in the total photonuclear cross section from the $\Delta$-resonance region up to the region where shadowing effects are known to exist. A consistent picture is obtained by simply assuming a density dependence of the different mechanisms of resonance broadening and shadowing. The $\Delta$-mass shift is found to increase with $A$.
Entanglement measurement of the quadrature components without the homodyne detection in the spatially multi-mode far-field
T. Golubeva,Yu. Golubev,K. Samburskaya,C. Fabre,N. Treps,M. Kolobov
Physics , 2009, DOI: 10.1103/PhysRevA.81.013831
Abstract: We consider the measuring procedure that in principle allows to avoid the homodyne detection for the simultaneous selection of both quadrature components in the far-field. The scheme is based on the use of the coherent sources of the non-classical light. The possibilities of the procedure are illustrated on the basis of the use of pixellised sources, where the phase-locked sub-Poissonian lasers or the degenerate optical parametric oscillator generating above threshold are chosen as the pixels. The theory of the pixellised source of the spatio-temporal squeezed light is elaborated as a part of this investigation.
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