Publications by authors named "Tonoyan A"

Background: The coronavirus disease 2019 outbreak (COVID-19) caused by the SARS-CoV coronavirus, has been declared as a pandemic by the World Health Organization on 11 March 2020, as a result of which about 315,000,000 people all over the world have been infected and more than 5,000,000 died.

Objective: Many scientific articles have been published concerning histopathological changes in different organs, but data concerning the lung changes of pregnant and postpartum period women who died of COVID-19 infections are still scarce. The aim of our study was to review and summarize autopsy findings and histopathological changes in lungs of pregnant and postpartum period women who died of COVID-19 infections in Armenia during 2020-2021.

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atoms have the smallest ground state () hyperfine splitting of all the most naturally abundant alkali isotopes and, consequently, the smallest characteristic magnetic field value =/≈170, where is the ground state's magnetic dipole interaction constant. In the hyperfine Paschen-Back regime (≫, where is the magnitude of the external magnetic field applied on the atoms), only eight Zeeman transitions are visible in the absorption spectrum of the line of , while the probabilities of the remaining 16 Zeeman transitions tend to zero. In the case of , this behavior is reached already at relatively low magnetic field >.

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We present the measurements of the photoionization cross sections of the excited P and S states of ultracold Sr atoms at 389.889 nm wavelength, which is the magic wavelength of the S-P clock transition. The photoionization cross section of the P state is determined from the measured ionization rates of Sr in the magneto-optical trap in the P state to be 2.

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Dark resonances were formed via electromagnetically induced transparency for the first time, to the best of our knowledge, involving magnetically induced ΔF=±2 atomic transitions of alkali metal atoms, which are forbidden at zero magnetic field. The probability of these transitions undergoes rapid growth when 300-3000 G magnetic field is applied, allowing formation of dark resonances, widely tunable in the GHz range. It is established that for ΔF=+2 (ΔF=-2) transition, the coupling laser tuned to ΔF=+1 (ΔF=-1) transition of the hyperfine Λ-system must be σ (σ) polarized, manifesting anomalous circular dichroism.

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Unlabelled: Because of the spread to different anatomical regions, craniofacial tumors (CFTs) usually receive blood supply from several arterial systems, and CFT removal is often accompanied by abundant blood loss.

Purpose: The study purpose was to develop an algorithm of diagnostic angiography for planning surgical treatment of CFT patients.

Material And Methods: Complex preoperative angiography was performed in 72 patients with craniofacial tumors, aged 10 to 78 years (mean age, 45.

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Modern diffusion MR protocols allow one to acquire the multi-shell diffusion data with high diffusion weightings in a clinically feasible time. In the present work we assessed three diffusion approaches based on diffusion and kurtosis tensor imaging (DTI, DKI), and neurite orientation dispersion and density imaging (NODDI) as possible biomarkers for human brain glioma grade differentiation based on the one diffusion protocol. We used three diffusion weightings (so called b-values) equal to 0, 1000, and 2500s/mm with 60 non-coplanar diffusion directions in the case of non-zero b-values.

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Diffusion magnetic resonance imaging (dMRI) is a powerful tool in clinical applications, in particular, in oncology screening. dMRI demonstrated its benefit and efficiency in the localisation and detection of different types of human brain tumours. Clinical dMRI data suffer from multiple artefacts such as motion and eddy-current distortions, contamination by noise, outliers etc.

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Background: Practical application of methods for intravital examination of the brain pathways, such as preoperative diffusion tensor imaging (DTI) tractography and intraoperative neurophysiological monitoring, facilitates safer resection of intracranial tumors located near the pyramidal tracts (PTs).

Purpose: The study purpose was to investigate the relationships between intracerebral tumors of different histological nature and the pyramidal tract based on preoperative DTI tractography and various methods of intraoperative neurophysiological monitoring for intraoperative identification of the pyramidal tract, depending on different variants of the topographo-anatomic relationships between the pyramidal fascicle and the tumor.

Material And Methods: The study included 29 patients with supratentorial tumors of a different histological structure.

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Unlabelled: The study is devoted to the use of a minimally invasive method of SCT perfusion for the differential diagnosis of sellar and pаrаsellar tumors. Given a wide differential diagnostic range of tumors occurring in this area, the tumor perfusion indicators were used as an auxiliary diagnostic criterion.

Material And Methods: The study analyzed outcomes in 115 patients with various tumors of the sellar area who underwent surgery or biopsy for histological verification of the diagnosis.

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Unlabelled: Despite the obvious progress in modern neurosurgery, surgery for glial tumors of the insular lobe is often associated with a high risk of postoperative neurological deficit, which is primarily caused by damage to perforating arteries of the M1 segment of the middle cerebral artery.

Objective: The work is aimed at evaluating the effectiveness of high resolution time-of-flight (3D-TOF) MR angiography in imaging of medial and lateral lenticulostriate arteries and determining their relationship to tumor edge in patients with gliomas of the insula.

Material And Methods: 3D-TOF MR angiography data were analyzed in 20 patients with primarily diagnosed cerebral gliomas involving the insula.

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Intracerebral tumors of the insular lobe are quite frequent, however treatment of patients with this pathology still remains a challenging and controversial issue of neurosurgery. First of all, this is associated with the localization of tumors in the area of eloquent anatomical structures: M1--M2 segment of the middle cerebral artery, lenticulostriate arteries, basal ganglia, and internal capsule, which causes a high rate of postoperative complications in these patients. Most insular tumors are amenable for resection with a reasonable rate of postoperative complications, although most of the surgery-related complications resulting in substantial deficits are due to lesions of eloquent anatomical structures located in this compact anatomical space.

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Unlabelled: The aim of the study was to assess the capabilities of diffusion kurtosis imaging (DKI) in diagnosis of the glioma proliferative activity and to evaluate a relationship between the glioma proliferative activity index and diffusion parameters of the contralateral normal appearing white matter (CNAWM).

Material And Methods: The study included 47 patients with newly diagnosed brain gliomas (23 low grade, 13 grade III, and 11 grade IV gliomas). We determined a relationship between absolute and normalized parameters of the diffusion tensor (mean (MD), axial (AD), and radial (RD) diffusivities; fractional (FA) and relative (RA) anisotropies) and diffusion kurtosis (mean (MK), axial (AK), and radial (RK) kurtosis; kurtosis anisotropy (KA)) and the proliferative activity index in the most malignant glioma parts (p<0.

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The existence of crossover resonances makes saturated-absorption (SA) spectra very complicated when external magnetic field B is applied. It is demonstrated for the first time, to the best of our knowledge, that the use of micrometric-thin cells (MTCs, L≈40  μm) allows application of SA for quantitative studies of frequency splitting and shifts of the Rb atomic transitions in a wide range of external magnetic fields, from 0.2 up to 6 kG (20-600 mT).

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A search is presented for dark matter pair production in association with a W or Z boson in pp collisions representing 20.3  fb(-1) of integrated luminosity at √s=8  TeV using data recorded with the ATLAS detector at the Large Hadron Collider. Events with a hadronic jet with the jet mass consistent with a W or Z boson, and with large missing transverse momentum are analyzed.

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This Letter presents measurements of the polarization of the top quark in top-antitop quark pair events, using 4.7  fb(-1) of proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider at √s=7  TeV. Final states containing one or two isolated leptons (electrons or muons) and jets are considered.

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This paper presents a study of the performance of the muon reconstruction in the analysis of proton-proton collisions at [Formula: see text] TeV at the LHC, recorded by the ATLAS detector in 2010. This performance is described in terms of reconstruction and isolation efficiencies and momentum resolutions for different classes of reconstructed muons. The results are obtained from an analysis of [Formula: see text] meson and [Formula: see text] boson decays to dimuons, reconstructed from a data sample corresponding to an integrated luminosity of 40 pb[Formula: see text].

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A measurement is presented of the [Formula: see text] production cross section at [Formula: see text] = 7 TeV using [Formula: see text] collision data corresponding to an integrated luminosity of 383 [Formula: see text], collected with the ATLAS experiment at the LHC. Selection of [Formula: see text](1020) mesons is based on the identification of charged kaons by their energy loss in the pixel detector. The differential cross section is measured as a function of the transverse momentum, [Formula: see text], and rapidity, [Formula: see text], of the [Formula: see text](1020) meson in the fiducial region 500 [Formula: see text] 1200 MeV, [Formula: see text] 0.

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Measurements of the variation of inclusive jet suppression as a function of relative azimuthal angle, Δφ, with respect to the elliptic event plane provide insight into the path-length dependence of jet quenching. ATLAS has measured the Δφ dependence of jet yields in 0.14 nb(-1) of √(s(NN))=2.

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Two-particle correlations in relative azimuthal angle (Δø) and pseudorapidity (Δη) are measured in sqrt[s(NN)] = 5.02 TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1 μb(-1) of data as a function of transverse momentum (p(T)) and the transverse energy (ΣE(T)(Pb)) summed over 3.

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The ATLAS experiment has observed 1995 Z boson candidates in data corresponding to 0.15  nb(-1) of integrated luminosity obtained in the 2011 LHC Pb+Pb run at sqrt[s(NN)]=2.76  TeV.

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Results of a search for new phenomena in events with an energetic photon and large missing transverse momentum in proton-proton collisions at sqrt[s] = 7 TeV are reported. Data collected by the ATLAS experiment at the LHC corresponding to an integrated luminosity of 4.6 fb(-1) are used.

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This Letter presents a search for magnetic monopoles with the ATLAS detector at the CERN Large Hadron Collider using an integrated luminosity of 2.0  fb(-1) of pp collisions recorded at a center-of-mass energy of sqrt[s]=7  TeV. No event is found in the signal region, leading to an upper limit on the production cross section at 95% confidence level of 1.

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Article Synopsis
  • The inclusive jet cross-section has been measured in proton-proton collisions at a specified energy level using data from the ATLAS detector at the Large Hadron Collider, with focus on a 2011 dataset.
  • Jets were identified using a specific algorithm with two different radius settings, and the double-differential cross-section is analyzed based on jet momentum and rapidity within defined ranges.
  • The study compares findings against QCD predictions and includes analyses that can refine our understanding of parton distribution functions by addressing systematic uncertainties and correlations between measurements.
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The luminosity calibration for the ATLAS detector at the LHC during collisions at [Formula: see text] in 2010 and 2011 is presented. Evaluation of the luminosity scale is performed using several luminosity-sensitive detectors, and comparisons are made of the long-term stability and accuracy of this calibration applied to the collisions at [Formula: see text]. A luminosity uncertainty of [Formula: see text] is obtained for the 47 pb of data delivered to ATLAS in 2010, and an uncertainty of [Formula: see text] is obtained for the 5.

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A search for a charged Higgs boson () in [Formula: see text] decays is presented, where one of the top quarks decays via →, followed by → two jets ([Formula: see text]). The other top quark decays to , where the  boson then decays into a lepton (/) and a neutrino. The data were recorded in collisions at [Formula: see text] by the ATLAS detector at the LHC in 2011, and correspond to an integrated luminosity of 4.

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