127 research outputs found

    Stability of holonomic quantum computations

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    We study the stability of holonomic quantum computations with respect to errors in assignment of control parameters. The general expression for fidelity is obtaned. In the small errors limit the simple formulae for the fidelity decrease rate is derived.Comment: 7 page

    Field-theoretical approach to particle oscillations in absorbing matter

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    The abab oscillations in absorbing matter are considered. The standard model based on optical potential does not describe the total abab transition probability as well as the channel corresponding to absorption of the bb-particle. We calculate directly the off-diagonal matrix element in the framework of field-theoretical approach. Contrary to one-particle model, the final state absorption does not tend to suppress the channels mentioned above or, similarly, calculation with hermitian Hamiltonian leads to increase the corresponding values. The model reproduces all the results on the particle oscillations, however it is oriented to the description of the above-mentioned channels. Also we touch on the problem of infrared singularities. The approach under study is infrared-free.Comment: 27 pages, 8 figure

    Critical Examination of the "Field-Theoretical Approach" to the Neutron-Antineutron Oscillations in Nuclei

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    We demonstrate that so called "infrared divergences" which have been discussed in some publications during several years, do not appear within the correct treatment of analytical properties of the transition amplitudes, in particular, of the second order pole structure of the amplitudes describing the nnˉn - \bar n transition in nuclei. Explicit calculation with the help of the Feynman diagram technique shows that the neutron-antineutron oscillations are strongly suppressed in the deuteron, as well as in heavier nuclei, in comparison with the oscillations in vacuum. General advantages and some difficulties of the field theoretical methods applied in nuclear theory are reminded for the particular example of the parity violating npdγnp\to d\gamma capture amplitude.Comment: 15 pages, 4 figures; prepared for Eur.Phys.J.

    In search of the visual pigment template

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    Absorbance spectra were recorded by microspectrophotometry from 39 different rod and cone types representing amphibians, reptiles, and fishes, with A1- or A2-based visual pigments and [lambda]max ranging from 357 to 620 nm. The purpose was to investigate accuracy limits of putative universal templates for visual pigment absorbance spectra, and if possible to amend the templates to overcome the limitations. It was found that (1) the absorbance spectrum of frog rhodopsin extract very precisely parallels that of rod outer segments from the same individual, with only a slight hypsochromic shift in [lambda]max, hence templates based on extracts are valid for absorbance in situ; (2) a template based on the bovine rhodopsin extract data of Partridge and De Grip (1991) describes the absorbance of amphibian rod outer segments excellently, contrary to recent electrophysiological results; (3) the [lambda]max/[lambda] invariance of spectral shape fails for A1 pigments with small [lambda]max and for A2 pigments with large [lambda]max, but the deviations are systematic and can be readily incorporated into, for example, the Lamb (1995) template. We thus propose modified templates for the main “[alpha]-band” of A1 and A2 pigments and show that these describe both absorbance and spectral sensitivities of photoreceptors over the whole range of [lambda]max. Subtraction of the [alpha]-band from the full absorbance spectrum leaves a “[beta]-band” described by a [lambda]max-dependent Gaussian. We conclude that the idea of universal templates (one for A1- and one for A2-based visual pigments) remains valid and useful at the present level of accuracy of data on photoreceptor absorbance and sensitivity. The sum of our expressions for the [alpha]- and [beta]-band gives a good description for visual pigment spectra with [lambda]max > 350 nm

    Hard-to-recover reserves of Yugra oil (West Siberia)

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    Criteria of hard-to-recover reserves, results and opportunities of their using for development in the conditions of Yugra fields are analyzed in the article.В статье анализируются критерии трудноизвлекаемых запасов, результаты и возможности их использования для разработки в условиях югорских месторождений.У статті аналізуються критерії важко видобувних запасів, результати і можливості їх використання для розробки в умовах Югорський родовищ

    Processing of acousto-optic images at early diagnosis of the functional state of the developing biosystem

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    The task of studying the embryo development at an early stage is considered. For this, hyperspectral imaging using an acousto-optical tunable filter is proposed. Acousto-optic visualization of the early developmental stages of the loach Misgurnus fossilis embryo showed a regular change in the spectral characteristics of different image areas corresponding to the tissues and body fluids, depending on the functional state of the embryo. This is manifested in the regular arrangement of a discrete set of maxima in the optical absorption spectrum with a distance of 20 and 30 nm between them. Value 20 nm corresponds to the normal development of biological tissue. The appearance of the value 30 nm between the maxima of neighboring optical absorption bands indicates the development of pathological processes in the biosystem. Such deviations from the norm are characteristic of germinal tissues, and they are absent in the perivitelline fluid. Therefore, for the early diagnosis of the physiological state of a developing biosystem, special attention should be paid to optical absorption spectra, in which 30 nm intervals between the maxima of the neighboring absorption bands prevail

    Study of KS KL Coupled Decays and KL -Be Interactions with the CMD-2 Detector at VEPP-2M Collider

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    The integrated luminosity about 4000 inverse nanobarn of around phi meson mass ( 5 millions of phi mesons) has been collected with the CMD-2 detector at the VEPP-2M collider. A latest analysis of the KS KL coupled decays based on 30 % of available data is presented in this paper. The KS KL pairs from phi meson decays were reconstructed in the drift chamber when both kaons decayed into two charged particles. From a sample of 1423 coupled decays a selection of candidates to the CP violating KL into pi+ pi- decay was performed. CP violating decays were not identified because of the domination of events with a KL regenerating at the Be beam pipe into KS and a background from KL semileptonic decays. The regeneration cross section of 110 MeV/c KL mesons was found to be 53 +- 17 mb in agreement with theoretical expectations. The angular distribution of KS mesons after regeneration and the total cross section of KL for Be have been measured.Comment: 14 pages, 8 figure

    The Atmospheric Chemistry Suite (ACS) of Three Spectrometers for the ExoMars 2016 Trace Gas Orbiter

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    The Atmospheric Chemistry Suite (ACS) package is an element of the Russian contribution to the ESA-Roscosmos ExoMars 2016 Trace Gas Orbiter (TGO) mission. ACS consists of three separate infrared spectrometers, sharing common mechanical, electrical, and thermal interfaces. This ensemble of spectrometers has been designed and developed in response to the Trace Gas Orbiter mission objectives that specifically address the requirement of high sensitivity instruments to enable the unambiguous detection of trace gases of potential geophysical or biological interest. For this reason, ACS embarks a set of instruments achieving simultaneously very high accuracy (ppt level), very high resolving power (>10,000) and large spectral coverage (0.7 to 17 μm—the visible to thermal infrared range). The near-infrared (NIR) channel is a versatile spectrometer covering the 0.7–1.6 μm spectral range with a resolving power of ∼20,000. NIR employs the combination of an echelle grating with an AOTF (Acousto-Optical Tunable Filter) as diffraction order selector. This channel will be mainly operated in solar occultation and nadir, and can also perform limb observations. The scientific goals of NIR are the measurements of water vapor, aerosols, and dayside or night side airglows. The mid-infrared (MIR) channel is a cross-dispersion echelle instrument dedicated to solar occultation measurements in the 2.2–4.4 μm range. MIR achieves a resolving power of >50,000. It has been designed to accomplish the most sensitive measurements ever of the trace gases present in the Martian atmosphere. The thermal-infrared channel (TIRVIM) is a 2-inch double pendulum Fourier-transform spectrometer encompassing the spectral range of 1.7–17 μm with apodized resolution varying from 0.2 to 1.3 cm−1. TIRVIM is primarily dedicated to profiling temperature from the surface up to ∼60 km and to monitor aerosol abundance in nadir. TIRVIM also has a limb and solar occultation capability. The technical concept of the instrument, its accommodation on the spacecraft, the optical designs as well as some of the calibrations, and the expected performances for its three channels are described

    The COMPASS Experiment at CERN

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    The COMPASS experiment makes use of the CERN SPS high-intensitymuon and hadron beams for the investigation of the nucleon spin structure and the spectroscopy of hadrons. One or more outgoing particles are detected in coincidence with the incoming muon or hadron. A large polarized target inside a superconducting solenoid is used for the measurements with the muon beam. Outgoing particles are detected by a two-stage, large angle and large momentum range spectrometer. The setup is built using several types of tracking detectors, according to the expected incident rate, required space resolution and the solid angle to be covered. Particle identification is achieved using a RICH counter and both hadron and electromagnetic calorimeters. The setup has been successfully operated from 2002 onwards using a muon beam. Data with a hadron beam were also collected in 2004. This article describes the main features and performances of the spectrometer in 2004; a short summary of the 2006 upgrade is also given.Comment: 84 papes, 74 figure

    Measurement of the ϕ\phi meson parameters with CMD-2 detector at VEPP-2M Collider

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    About 300 000 e+eϕKL0KS0e^+e^-\to \phi\to K^0_L K^0_S events in the center of mass energy range from 984 to 1040 MeV were used for the measurement of the ϕ\phi meson parameters. The following results have been obtained: σ0=(1367±15±21)nb,mϕ=(1019.504±0.011±0.033)MeV/c2,Γϕ=(4.477±0.036±0.022)MeV,Γe+eB(ϕKL0KS0)=(4.364±0.048±0.065)104\sigma_0 = (1367 \pm 15 \pm 21) nb, m_{\phi}=(1019.504 \pm 0.011 \pm 0.033) MeV/c^2, \Gamma_\phi=(4.477 \pm 0.036 \pm 0.022) MeV, \Gamma_{e^+e^-}\cdot B(\phi\to K^0_L K^0_S) = (4.364 \pm 0.048 \pm 0.065)\cdot 10^{-4} MeV.Comment: 13 pages, 5 figures, 5 table
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