Publications by authors named "Oganesyan G"

A long gamma-ray burst (GRB) is observed when the collapse of a massive star produces an ultrarelativistic outflow pointed toward Earth. Gamma-ray spectra of long GRBs are smooth, typically modeled by joint power-law segments describing a continuum, with no detected spectral lines. We report a significant (>6σ) narrow emission feature at ~10 mega-electron volts (MeV) in the spectrum of the bright GRB 221009A.

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In this Letter, we present the design and performance of the frequency-dependent squeezed vacuum source that will be used for the broadband quantum noise reduction of the Advanced Virgo Plus gravitational-wave detector in the upcoming observation run. The frequency-dependent squeezed field is generated by a phase rotation of a frequency-independent squeezed state through a 285 m long, high-finesse, near-detuned optical resonator. With about 8.

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An energetic γ-ray burst (GRB), GRB 211211A, was observed on 11 December 2021. Despite its long duration, typically associated with bursts produced by the collapse of massive stars, the observation of an optical-infrared kilonova points to a compact binary merger origin. Here we report observations of a significant (more than five sigma) transient-like emission in the high-energy γ-rays of GRB 211211A (more than 0.

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Article Synopsis
  • The study investigates compact binary coalescences with at least one component mass between 0.2 and 1.0 solar masses using data from Advanced LIGO and Advanced Virgo detectors over six months in 2019, but they found no significant gravitational wave candidates.
  • The analysis leads to an upper limit on the merger rate of subsolar binaries ranging from 220 to 24,200 Gpc⁻³ yr⁻¹, based on the detected signals’ false alarm rate.
  • The researchers use these limits to set new constraints on two models for subsolar-mass compact objects: primordial black holes (suggesting they make up less than 6% of dark matter) and
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The proposed THESEUS mission will vastly expand the capabilities to monitor the high-energy sky. It will specifically exploit large samples of gamma-ray bursts to probe the early universe back to the first generation of stars, and to advance multi-messenger astrophysics by detecting and localizing the counterparts of gravitational waves and cosmic neutrino sources. The combination and coordination of these activities with multi-wavelength, multi-messenger facilities expected to be operating in the 2030s will open new avenues of exploration in many areas of astrophysics, cosmology and fundamental physics, thus adding considerable strength to the overall scientific impact of THESEUS and these facilities.

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γ-ray bursts (GRBs) are short-lived transients releasing a large amount of energy (10 - 10 erg) in the keV-MeV energy range. GRBs are thought to originate from internal dissipation of the energy carried by ultra-relativistic jets launched by the remnant of a massive star's death or a compact binary coalescence. While thousands of GRBs have been observed over the last thirty years, we still have an incomplete understanding of where and how the radiation is generated in the jet.

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We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. A template-based search for short-duration transient signals does not yield a detection.

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The main purpose of an application performance monitoring/management (APM) software is to ensure the highest availability, efficiency and security of applications. An APM software accomplishes the main goals through automation, measurements, analysis and diagnostics. Gartner specifies the three crucial capabilities of APM softwares.

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A decrease of two-gamma annihilation rate of a positron in a strong spin-orbit field of the annihilation site of bismuth impurity centerBi (= 9/2) in silicon with natural isotope composition was revealed (is the nuclear spin). This decrease was observed along with increasing occupancy of Bi donor states (binding energy{Bi} ≈ 69 meV). Atoms ofSi (= 1/2) isotope are involved in spin interactions of positron with Bi impurity centers.

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The quantum radiation pressure and the quantum shot noise in laser-interferometric gravitational wave detectors constitute a macroscopic manifestation of the Heisenberg inequality. If quantum shot noise can be easily observed, the observation of quantum radiation pressure noise has been elusive, so far, due to the technical noise competing with quantum effects. Here, we discuss the evidence of quantum radiation pressure noise in the Advanced Virgo gravitational wave detector.

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Article Synopsis
  • On May 21, 2019, Advanced LIGO and Virgo detected a significant gravitational-wave signal known as GW190521, indicating a high probability event with a low chance of false alarms.
  • The signal suggests it resulted from the merger of two black holes, one around 85 solar masses and the other about 66 solar masses, with the primary black hole likely being an intermediate mass black hole.
  • The source of the merger is estimated to be about 5.3 billion light-years away, and the rate of similar black hole mergers is estimated to be about 0.13 mergers per billion cubic parsecs per year.
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Current interferometric gravitational-wave detectors are limited by quantum noise over a wide range of their measurement bandwidth. One method to overcome the quantum limit is the injection of squeezed vacuum states of light into the interferometer's dark port. Here, we report on the successful application of this quantum technology to improve the shot noise limited sensitivity of the Advanced Virgo gravitational-wave detector.

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Article Synopsis
  • The study investigates the existence of subsolar mass ultracompact objects by analyzing data from Advanced LIGO's second observing run and includes the impact of spin on gravitational waves.
  • No suitable gravitational-wave candidates were found for binaries with at least one component between 0.2 and 1.0 solar masses, leading to significant constraints on their binary merger rates.
  • The findings suggest that such ultracompact objects likely do not form through conventional stellar evolution, and they outline how these constraints on merger rates can be applied to different black hole population models that predict subsolar mass binaries.
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Background: Shave biopsy may not be able to accurately distinguish squamous cell carcinoma in situ (SCCIS) from invasive squamous cell carcinoma (SCC). Information on the incidence of biopsy-proven SCCIS upstaged to SCC after a more complete histologic examination is limited.

Objective: To determine the incidence and clinical risk factors associated with upstaging the biopsy diagnosis of SCCIS into invasive SCC based on findings during Mohs micrographic surgery (MMS).

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This study is a continuation of our research of phenomenology and mechanisms of motion sickness (MS) and the relation of this phenomenon to features of sleep-wake cycle (SWC) changes. It presents data about the effect of MS on SWC in 30-day-old intact rats and rats exposed previously to prenatal hypoxia on days 13 and 19 of gestation. In all groups of animals MS was shown to reduce significantly the waking time and to increase the time of paradoxical sleep (PS).

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Sleep is characterized by cycling and consecutive alternation of different phases and stages, each of them featuring intrinsic changes of vegetative regulation with oscillations of heartbeat rate that may cause development of cardiac rhythm disorders especially under presence of concomitant somatic diseases. This paper deals with the problems of interrelationships between disturbances of heart conduction and obstruc- tive sleep apnea. It is shown that some mechanisms of the occurrence of brady-arrhythmias (first of all, features of vegetative regulation with increasing parasympathetic tone) under sleep arrests are inherent to human divers as well as to mammals conducting water or near-water way of living associated with forced breathing delays at diving and prolonged staying under water.

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Importance: Immunosuppression (IS), such as in solid-organ transplant recipients (SOTRs) and patients with human immunodeficiency virus (HIV) or hematologic malignant neoplasms, increases the risk of developing nonmelanoma skin cancers (NMSCs). However, it is unknown whether IS patients are at increased risk of developing NMSCs with aggressive subclinical extensions (NMSC-ASE), which may extend aggressively far beyond conventional surgical margins.

Objective: To study clinical characteristics of NMSC-ASE among immunocompetent (IC) and various subgroups of IS patients and to suggest a predictive model for NMSC-ASE lesions.

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The role of orexin in the organization of sleep-wakefulness cycle (SWC) is well known. The aim of this study was to examine the terms of formation of the orexinergic system in the rat postnatal ontogenesis and to assess the role of orexin A in SWC organization under normal conditions and after prenatal hypoxia realized on days 14 and 19 of the embryogenesis. SWC was investigated in 30-day-old rats with elect- rodes implanted into the somatosensory and occipital cortex.

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The effects of electrical stimulation of nucleus reticularis pontis oralis on the behavior and brain electrical activity during all phases of the sleep-waking cycle was studied in Krushinskii-Molodkina strain rats, which have an inherited predisposition to audiogenic seizures. Electrical stimulation with 7 Hz frequency in the deep stage of slow-wave sleep cause appearance the fast-wave sleep. Similar stimulation during fast-wave sleep periods did not effects on the electrographic patterns and EEG spectral characteristics of hippocampus, visual, auditory and somatocnen nrnrenc nf the cnrtey ThPe sfimul1stinns did nnt break a fast-wave sleenhut increased almost twice due the duration of these sleep episodes.

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Erythema induratum of Bazin (EIB) is a rare tuberculid that typically affects middle-aged women. We report a unique case of EIB in a 57-year-old Hispanic woman who presented with recurrent painful plaques and nodules on the lower extremities, specifically on the pretibial area of the legs and dorsal aspect of the feet, with a severe burning sensation on the feet that resolved after antituberculosis therapy. We review the characteristics of EIB and examine how the unique presentation of peripheral neuropathy may relate to the pathophysiology of this disease.

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Objective: To study different methods of treatment of patients with myofascial pain syndrome (MFPS).

Material And Methods: We evaluated the efficacy of complex treatment in 152 patients with chronic tension-type headache (СЕЕР) and 96 patients with facial MFPS. The treatment included standard methods (reflex therapy of СЕЕР and local injections of a combination of local anesthetics with small doses of steroids in trigger points in patients with facial MFPS.

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Background: Potential dangers associated with smoke generated during electrosurgery have been described. However, the use of smoke management in dermatology is unknown. There is no objective data showing the amount or the composition of the smoke generated in dermatologic surgeries.

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Importance: Detailed information regarding perioperative risk and adverse events associated with Mohs micrographic surgery (MMS) can guide clinical management. Much of the data regarding complications of MMS are anecdotal or report findings from single centers or single events.

Objectives: To quantify adverse events associated with MMS and detect differences relevant to safety.

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Background: Repair of below-the-knee lower extremity defects after Mohs micrographic surgery (MMS) that are not amenable to primary closure can be challenging given the high propensity for complications. No criterion standard exists for management of these wounds, but secondary-intention healing, partial- and full-thickness skin grafts (FTSGs), and various flaps are possible options to manage these wounds. Few data exist on the efficacy of FTSG repairs for lower extremity wounds.

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Microstructure and thermal stability of the radiation defects in n-FZ-Si ([P] ≈ 7 × 10(15) cm(-3)) single crystals have been investigated. The radiation defects have been induced by irradiation with 15 MeV protons and studied by means of both the positron lifetime spectroscopy and low-temperature measurements of the Hall effect. At each step of the isochronal annealing over the temperature range ∼60-700 °C the positron lifetime has been measured for the temperature interval ∼30-300 K, and for samples-satellites the temperature dependences of the charge carriers and mobility have been determined over the range ∼4.

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