The Transient Ultra-luminous X-ray Source, ULX-4, in M51

We present the results of a temporal and spectral analysis of the transient source ULX-4 in the galaxy M51. The data used were drawn from Chandra, XMM-Newton and Swift-XRT archives, spanning the years 2000-2019. The X-ray flux of the source is seen to vary by two orders of magnitudes within a month but a short-term variability was not observed over the time intervals of 100-2000 second in the 0.3-10 keV energy band. We find some evidence for the existence of bi-modality feature in the flux distribution of ULX-4. We identified two optical sources as possible counterparts within an error radius of 0."18 at 95% confidence level for ULX-4 based on the archival HST/ACS and HST/WFC3 data. Blackbody fits of the spectral energy distributions (SEDs) indicate the spectral type to be B-type stars. One of these counterparts exhibits a low-amplitude optical periodicity of 264 days in the F606W filter; if we assume this apparent periodicity is associated with the orbital motion of the donor, then it is more likely that the donor is a red supergiant satisfying the long periodicity and accretion via Roche-lobe overflow. Consequently, the SED would then have to be interpreted as a superposition of emissions from a cold donor and a hot flow component, most likely from an accretion disk. If, on the other hand, the periodicity is super orbital in nature i.e., due to possible interactions of the compact object with a circumstellar disk, the donor could then be a Be/X star hosting a neutron star.Comment: Accepted for publication in MNRAS. 16 pages, 12 figures, 6 table

Дослідження випромінювальної здатності мінералів для побудови мікрохвильових генераторів медичного призначення

At implementation of physical therapy procedures, advantage gets a simple and reliable medical apparatus. In a complete measure it belongs and to the apparatus for microwave therapy in the range of frequencies 37 – 78 GGc. At the same time the apparatus SHF of range differs complication of construction, high cost and insufficient reliability. To more simple and reliable devices of the medical setting it follows to take the thermal generators of SHF-range. One of basic lacks of similar medical generators there is small initial power. Authors are conduct experimental researches of materials of natural origin (minerals) for the working body of thermal generator, what would provide the increase of initial power these medical devices. The results of these researches is an exposure of materials in which a radiate ability in 4 times is greater from usually in-use – feroapoksidu.При выполнении физиотерапевтических процедур, преимущество предоставляется простой и надежной медицинской аппаратуре. В полной мере это относится и к аппаратуре для микроволновой терапии в диапазоне частот 37 – 78 ГГц. В то же время аппаратура мм-диапазона отличается сложностью построения, высокой стоимостью и недостаточной надежностью. К более простым и надежным приборам медицинского назначения следует отнести тепловые генераторы мм-диапазона. Одним из основных недостатков подобных медицинских генераторов есть малая исходная мощность. Авторами проведены экспериментальные исследования материалов естественного происхождения (минералов) для использования в качестве рабочего тела теплового генератора, способных обеспечивать увеличение выходной мощности этих медицинских приборов. Результатами исследований является выявле-ние материалов в которых излучательная способность в 4 раза большая от обычно используемого – фероапоксида.При виконанні фізіотерапевтичних процедур, перевага надається простій і надійній медичній апаратурі. В повній мірі це відноситься і до апаратури для мікрохвильової терапії в діапазоні частот 37 – 78 ГГц. В той же час апаратура мм діапазону відрізняється складністю побудови, високою вартістю та недостатньою надійністю. До більш простих і надійних приладів медичного призначення слід віднести теплові генератори мм-діапазону. Одним з основних недоліків подібних медичних генераторів є мала вихідна потужність. Авторами проведено експериментальні дослідження матеріалів природного походження (мінералів) для використання в якості робочого тіла теплового генератора, які б забезпечували збільшення вихідної потужності цих медичних приладів. Результатами цих досліджень є виявлення матеріалів в яких випромінювальна здатність в 4 рази більша від зазвичай використовуваного – фероапоксиду

Convergence of the Magnus series

The Magnus series is an infinite series which arises in the study of linear ordinary differential equations. If the series converges, then the matrix exponential of the sum equals the fundamental solution of the differential equation. The question considered in this paper is: When does the series converge? The main result establishes a sufficient condition for convergence, which improves on several earlier results.Comment: 11 pages; v2: added justification for conjecture, minor clarifications and correction

Scientific experimental bases for dry beneficiation of mineral ores

The article presents the results of research on the development of processes and equipment for ore preparation and pneumatic dry beneficiation of mineral ores. The methods of crushing and grinding before enrichment of minerals have been considered, dry enrichment of geomaterials is investigated. Highly efficient prototypes of beneficiation equipment are developed and tested: crushers of multiple dynamic impact RD-MDV-900, DKD-300, centrifugal grinders CMVU-800 and VCI-12, pneumatic separator POS-2000. Fundamental designs are created, and a number of new ore preparation and pneumatic beneficiation instruments are being designed. The efficiency of approbation of an autonomous dry beneficiation complex with new safe environmental standards for the processing of gold-bearing ores, which makes it possible to fully release and extract free gold with a particle size from 10,000 to 100 µm, is shown. The introduction of the dry beneficiation method is very promising for the mining industry. It will allow to reduce capital costs for the construction of stationary beneficiation plants, completely or partially withdraw from the use of process water, the construction of a water supply system, a traditional tailing dam, etc

One-dimensional Model of a Gamma Klystron

A new scheme for amplification of coherent gamma rays is proposed. The key elements are crystalline undulators - single crystals with periodically bent crystallographic planes exposed to a high energy beam of charged particles undergoing channeling inside the crystals. The scheme consists of two such crystals separated by a vacuum gap. The beam passes the crystals successively. The particles perform undulator motion inside the crystals following the periodic shape of the crystallographic planes. Gamma rays passing the crystals parallel to the beam get amplified due to interaction with the particles inside the crystals. The term `gamma klystron' is proposed for the scheme because its operational principles are similar to those of the optical klystron. A more simple one-crystal scheme is considered as well for the sake of comparison. It is shown that the gamma ray amplification in the klystron scheme can be reached at considerably lower particle densities than in the one-crystal scheme, provided that the gap between the crystals is sufficiently large.Comment: RevTeX4, 22 pages, 4 figure

Software systems for operation, control, and monitoring of the EBEX instrument

We present the hardware and software systems implementing autonomous operation, distributed real-time monitoring, and control for the EBEX instrument. EBEX is a NASA-funded balloon-borne microwave polarimeter designed for a 14 day Antarctic flight that circumnavigates the pole. To meet its science goals the EBEX instrument autonomously executes several tasks in parallel: it collects attitude data and maintains pointing control in order to adhere to an observing schedule; tunes and operates up to 1920 TES bolometers and 120 SQUID amplifiers controlled by as many as 30 embedded computers; coordinates and dispatches jobs across an onboard computer network to manage this detector readout system; logs over 3~GiB/hour of science and housekeeping data to an onboard disk storage array; responds to a variety of commands and exogenous events; and downlinks multiple heterogeneous data streams representing a selected subset of the total logged data. Most of the systems implementing these functions have been tested during a recent engineering flight of the payload, and have proven to meet the target requirements. The EBEX ground segment couples uplink and downlink hardware to a client-server software stack, enabling real-time monitoring and command responsibility to be distributed across the public internet or other standard computer networks. Using the emerging dirfile standard as a uniform intermediate data format, a variety of front end programs provide access to different components and views of the downlinked data products. This distributed architecture was demonstrated operating across multiple widely dispersed sites prior to and during the EBEX engineering flight.Comment: 11 pages, to appear in Proceedings of SPIE Astronomical Telescopes and Instrumentation 2010; adjusted metadata for arXiv submissio

European Strategy for Particle Physics -- Accelerator R&D Roadmap

The 2020 update of the European Strategy for Particle Physics emphasised the importance of an intensified and well-coordinated programme of accelerator R&D, supporting the design and delivery of future particle accelerators in a timely, affordable and sustainable way. This report sets out a roadmap for European accelerator R&D for the next five to ten years, covering five topical areas identified in the Strategy update. The R&D objectives include: improvement of the performance and cost-performance of magnet and radio-frequency acceleration systems; investigations of the potential of laser / plasma acceleration and energy-recovery linac techniques; and development of new concepts for muon beams and muon colliders. The goal of the roadmap is to document the collective view of the field on the next steps for the R&D programme, and to provide the evidence base to support subsequent decisions on prioritisation, resourcing and implementation.Comment: 270 pages, 58 figures. Editor: N. Mounet. LDG chair: D. Newbold. Panel chairs: P. V\'edrine (HFM), S. Bousson (RF), R. Assmann (plasma), D. Schulte (muon), M. Klein (ERL). Panel editors: B. Baudouy (HFM), L. Bottura (HFM), S. Bousson (RF), G. Burt (RF), R. Assmann (plasma), E. Gschwendtner (plasma), R. Ischebeck (plasma), C. Rogers (muon), D. Schulte (muon), M. Klein (ERL

Newtype single-layer magnetic semiconductor in transition-metal dichalcogenides VX 2 (X = S, Se and Te)

We present a newtype 2-dimensional (2D) magnetic semiconductor based on transition-metal dichalcogenides VX2 (X = S, Se and Te) via first-principles calculations. The obtained indirect band gaps of monolayer VS2, VSe2, and VTe2 given from the generalized gradient approximation (GGA) are respectively 0.05, 0.22, and 0.20 eV, all with integer magnetic moments of 1.0 μB. The GGA plus on-site Coulomb interaction U (GGA + U) enhances the exchange splittings and raises the energy gap up to 0.38~0.65 eV. By adopting the GW approximation, we obtain converged G0W0 gaps of 1.3, 1.2, and 0.7 eV for VS2, VSe2, and VTe2 monolayers, respectively. They agree very well with our calculated HSE gaps of 1.1, 1.2, and 0.6 eV, respectively. The gap sizes as well as the metal-insulator transitions are tunable by applying the in-plane strain and/or changing the number of stacking layers. The Monte Carlo simulations illustrate very high Curie-temperatures of 292, 472, and 553 K for VS2, VSe2, and VTe2 monolayers, respectively. They are nearly or well beyond the room temperature. Combining the semiconducting energy gap, the 100% spin polarized valence and conduction bands, the room temperature TC, and the in-plane magnetic anisotropy together in a single layer VX2, this newtype 2D magnetic semiconductor shows great potential in future spintronics