New Research in the Military History of the Late Rome and Early Byzantium

Submitted: 08.07.2020. Accepted: 15.10.2020.Поступила 08.07.2020. Принята 15.10.2020.A review of: Mekhamadiev, E. A. (2019). Voennaia organizatsiia pozdnei Rimskoi imperii v 253–353 gg.: ot reform imperatora Galliena do perioda Tetrarkhii (253–305) [A Military Organization of the Later Roman Empire in 253–353 AD: From Emperor Gallienus’ Reforms to the Age of the Tetrarchy (253–305)]. St Petersburg: Peterburgskoe Vostokovedenie Publishers. 406 p. This paper states that the monograph published E. A. Mekhamadiev, a researcher from St. Petersburg, is a fundamental study of the Later Roman military organization, with especial attention to the epigraphic and papyrological accounts. The use of these sources allows the author to reconstruct the history of specific military units, their spatial movements, participation in various military campaigns and wars, and changes in their ranks. Important is that Mekhamadiev examined the internal (organizational) structure of all regional armies of the Roman empire from 253 to 305 and not restricted himself to specific and narrow aspects of history of a particular province or country. The author of the book under present review has analysed the data related to both the eastern and the western imperial provinces, discovered close interrelations of the western and eastern provinces, and indicated permanent movements of the military units from the west to east and in the opposite direction depending on the geopolitical and home political situation.Рецензия на книгу: Мехамадиев Е. А. Военная организация поздней Римской империи в 253–353 гг.: от реформ императора Галлиена до периода Тетрархии (253–305). СПб. : Петербургское востоковедение, 2019. 406 с. В статье отмечается, что рецензируемая книга петербургского исследователя Е. А. Мехамадиева является фундаментальным исследованием по военной организации позднего Рима, в котором сделан особый акцент на данные эпиграфики и папирологии. Их привлечение позволили автору реконструировать историю отдельных войсковых подразделений, их территориальные перемещения, участие в различных военных кампаниях и походах, изменения рангов. Указывается, что Е. А. Мехамадиев рассмотрел внутреннюю (организационную) структуру всех региональных армий Рима с 253 по 305 г., не ограничился исследованием отдельных и узких сюжетов, связанных с историей отдельно взятой имперской провинции или региона. Автор рецензируемой книги проанализировал данные как по восточным, так и по западным провинциям империи, выявил тесную взаимосвязь западных и восточных провинций, указал на постоянные перемещения войсковых подразделений с запада на восток и в обратную сторону в зависимости от геополитической и внутриполитической ситуации

Ocular Manifestations In COVID-19: Clinical Case Reports And A Literature (Review)

Coronavirus disease 2019 (COVID-19) has affected more than 130 million people as of April 2021. During the current pandemic, SARS-CoV-2 has been found to cause conjunctivitis with anecdotal evidence of a wide range of manifestations from scleritis to retinitis, occlusive vasculitis and optic neuritis. The purpose of this study is to raise awareness about possible COVID-19 related ocular manifestations, including papillophlebitis, anterior ischemic optic neuropathy, uveitis and neuroretinitis. Further detailed analyses will be needed to elucidate the link between SARS-CoV-2 and ocular pathology

Search for a new gauge boson in the A′A' Experiment (APEX)

We present a search at Jefferson Laboratory for new forces mediated by sub-GeV vector bosons with weak coupling $\alpha'$ to electrons. Such a particle $A'$ can be produced in electron-nucleus fixed-target scattering and then decay to an $e^+e^-$ pair, producing a narrow resonance in the QED trident spectrum. Using APEX test run data, we searched in the mass range 175--250 MeV, found no evidence for an $A'\to e^+e^-$ reaction, and set an upper limit of $\alpha'/\alpha \simeq 10^{-6}$. Our findings demonstrate that fixed-target searches can explore a new, wide, and important range of masses and couplings for sub-GeV forces.Comment: 5 pages, 5 figures, references adde

Evidence for proton acceleration up to TeV energies based on VERITAS and Fermi-LAT observations of the Cas A SNR

We present a study of $\gamma$-ray emission from the core-collapse supernova remnant Cas~A in the energy range from 0.1GeV to 10TeV. We used 65 hours of VERITAS data to cover 200 GeV - 10 TeV, and 10.8 years of \textit{Fermi}-LAT data to cover 0.1-500 GeV. The spectral analysis of \textit{Fermi}-LAT data shows a significant spectral curvature around $1.3 \pm 0.4_{stat}$ GeV that is consistent with the expected spectrum from pion decay. Above this energy, the joint spectrum from \textit{Fermi}-LAT and VERITAS deviates significantly from a simple power-law, and is best described by a power-law with spectral index of $2.17\pm 0.02_{stat}$ with a cut-off energy of $2.3 \pm 0.5_{stat}$ TeV. These results, along with radio, X-ray and $\gamma$-ray data, are interpreted in the context of leptonic and hadronic models. Assuming a one-zone model, we exclude a purely leptonic scenario and conclude that proton acceleration up to at least 6 TeV is required to explain the observed $\gamma$-ray spectrum. From modeling of the entire multi-wavelength spectrum, a minimum magnetic field inside the remnant of $B_{\mathrm{min}}\approx150\,\mathrm{\mu G}$ is deduced.Comment: 33 pages, 9 Figures, 6 Table

New Measurements of the Transverse Beam Asymmetry for Elastic Electron Scattering from Selected Nuclei

We have measured the beam-normal single-spin asymmetry An in the elastic scattering of 1-3 GeV transversely polarized electrons from H-1 and for the first time from He-4, C-12, and Pb-208. For H-1, He-4, and C-12, the measurements are in agreement with calculations that relate A(n) to the imaginary part of the two-photon exchange amplitude including inelastic intermediate states. Surprisingly, the Pb-208 result is significantly smaller than the corresponding prediction using the same formalism. These results suggest that a systematic set of new A(n) measurements might emerge as a new and sensitive probe of the structure of heavy nuclei

Direct measurement of stellar angular diameters by the VERITAS Cherenkov Telescopes

The angular size of a star is a critical factor in determining its basic properties. Direct measurement of stellar angular diameters is difficult: at interstellar distances stars are generally too small to resolve by any individual imaging telescope. This fundamental limitation can be overcome by studying the diffraction pattern in the shadow cast when an asteroid occults a star, but only when the photometric uncertainty is smaller than the noise added by atmospheric scintillation. Atmospheric Cherenkov telescopes used for particle astrophysics observations have not generally been exploited for optical astronomy due to the modest optical quality of the mirror surface. However, their large mirror area makes them well suited for such high-time-resolution precision photometry measurements. Here we report two occultations of stars observed by the VERITAS Cherenkov telescopes with millisecond sampling, from which we are able to provide a direct measurement of the occulted stars' angular diameter at the $\leq0.1$ milliarcsecond scale. This is a resolution never achieved before with optical measurements and represents an order of magnitude improvement over the equivalent lunar occultation method. We compare the resulting stellar radius with empirically derived estimates from temperature and brightness measurements, confirming the latter can be biased for stars with ambiguous stellar classifications.Comment: Accepted for publication in Nature Astronom