Post-Mortem RT-PCR Assay for SARS-CoV-2 RNA in COVID-19 Patients’ Corneal Epithelium, Conjunctival and Nasopharyngeal Swabs

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease has been described to possibly be associated with ocular surface disturbances. However, whether the virus could invade ocular tissues still remains elusive. In the present study, we tried to investigate the post-mortem presence of SARS-CoV-2 RNA in corneal epithelium gathered by patients with an ante-mortem confirmed diagnosis of Coronavirus disease-19 (COVID-19). Cadavers with an ante-mortem confirmed diagnosis of moderate to severe COVID-19 were examined. Clinical and demographic features were retrieved from hospital patients’ notes. For each cadaver, corneal scrapings, conjunctival swabs (CS) and nasopharyngeal swabs (NPS) were collected to perform real-time reverse transcriptase polymerase chain reaction ((RT)-PCR) for SARS-CoV-2. Fourteen consecutive cadavers with an ante-mortem confirmed diagnosis of moderate to severe COVID-19 were examined. The last NPS performed ante-mortem confirmed SARS-CoV-2 infection in 12/14 (85.7%) patients. The mean death-to-swab time (DtS) was 3.15 ± 0.5 (2.10–5.1) h. The post-mortem NPS and CS found positive for SARS-CoV-2 RNA were 9/14 (64.3%) and 3/28 (10.7%), respectively. None of the corneal epithelium scrapes tested positive to RT-PCR for SARS-CoV-2 RNA. These data promote the SARS-CoV-2 as not able to contaminate the post-mortem corneal epithelium, while it can persist in different other structures of the ocular surface (i.e., the conjunctiva). It is reasonable to assume that such a contamination can occur ante-mortem too.

Free-surface disturbances due to the submersion of a cylindrical obstacle

We explore the initial perturbations that form on a liquid free surface as a result of the submersion of a circular cylinder beneath the surface, a scenario that arises in a number of diverse applications. The behaviour of the free surface is determined by transforming the equations of motion of the system via the Wehausen scheme, to variables for the free surface. A small-time series expansion is utilized to construct a recursive scheme that can be implemented numerically, and the time frame over which this approximation is valid is analysed. The resulting numerical model allows one to extend the results in the literature to study arbitrary cylinder sizes, including those where the cylinder is close to the free surface, and arbitrary cylinder motions. Of particular interest in this study was identifying the conditions under which strong jets would appear, and those were the free surface exhibited gravity waves. The formation of a central jet is found to be related to the growth of secondary, nonlinear waves, which rapidly merge as the obstacle is submerged. Classification maps are presented as a function of obstacle size and submersion speed, to identify the conditions which lead to jetting. Furthermore, the acceleration profile of the cylinder is shown to significantly affect the conditions under which jets form, which we argue is due to the rate at which energy is injected into the system.

Manifestations of instability during the collapse of metal liners of shaped charges and in related jet flows of dynamically deformed profiled bodies

The paper briefly analyzes a number of published works devoted to cumulative explosion under conditions of the possible development of surface instability of the collapsing liner of a shaped charge. Most studies stated that surface instability was initially initiated by harmonic surface disturbances or disturbances in the parameters of a given load simulating an explosive one. The instability manifested itself in the form of the development of surface disturbances over time; the absence or limited growth was considered as the preservation of the stability of the deformable shell. In addition to the influence of instability on cumulative processes, related jet flows were also investigated. This is the so-called explosive dispersion (dusting), which occurs both under the influence of the interference of shock waves and unloading waves, and in the presence of initial disturbances of the surface shape. The analysis is built within the framework of the phenomenological approach — both the main results of the experiments and their mathematical descriptions were considered, which in most cases were carried out from the positions established in the mechanics of continuous media, as well as with the help of numerical modeling. Based on the results, conclusions were formulated about the reasons and forms of manifestation of surface instability of collapsing metal liners of shaped charges, the nature of the development and parameters of functioning of such charges, as well as about the features and laws of this process.

A Coupled OpenFOAM-WRF Study on Atmosphere-Wake-Ocean Interaction

This work aims to better understand how small scale disturbances that are generated at the air-sea interface propagate into the surrounding atmosphere under realistic environmental conditions. To that end, a one-way coupled atmosphere-ocean model is presented, in which predictions of sea surface currents and sea surface temperatures from a microscale ocean model are used as constant boundary conditions in a larger atmospheric model. The coupled model consists of an ocean component implemented while using the open source CFD software OpenFOAM, an atmospheric component solved using the Weather Research and Forecast (WRF) model, and a Python-based utility foamToWRF, which is responsible for mapping field data between the ocean and atmospheric domains. The results are presented for two demonstration cases, which indicate that the proposed coupled model is able to capture the propagation of small scale sea surface disturbances in the atmosphere, although a more thorough study is required in order to properly validate the model.

Assessment of Mold Filling Rate Influence on Amount of Oxide Films in Castings by Numerical Simulation

The influence of the mold filling rate on the content of oxide films in aluminum alloy castings is considered. The existing methods for estimating the probability of formation and entrainment of oxide films in the bulk of the liquid, which are associated with surface disturbances during the melt flow through the channels of the mold, are analyzed. A criterion for estimating oxide impurities in the melt using numerical process modeling is proposed. A comparative analysis of the results of numerical simulation with the data of practical experiments obtained by M. V. Sharov and N. M. Galdin was performed. This comparative analysis and experience in the development of technological processes for shaped castings showed the possibility of using the criterion in numerical modeling.

Landscape Indication Of Permafrost Conditions For Geoecological Assessment & Mapping At Various Scales

In this paper, the features of landscape indication of permafrost characteristics required for assessing the environmental state at various research scales are discussed. A number of permafrost characteristics affect the geoecological state and stability of natural landscapes, especially in the context of climate warming and technogenic surface disturbances. These include the distribution, temperature regime, thickness and cryogenic structure of permafrost, seasonal freezing and thawing, as well as the development of cryogenic processes. Their determination through the landscape view, however, is ambiguous. The choice of certain permafrost characteristics for geoecological assessment is based on many years of experience in creating cryo-ecological maps on a landscape basis by the school of Faculty of Geography, Moscow State University. The recent studies on the identification of regional cryoindicators are analyzed, including the issues of cryogenic landscapes classification and clarification of the boundaries of geocryological zones using the landscape structural method. The content of the two maps, «Permafrost Landscape Differentiation Map of the Russia Cryolithozone» at a scale of 1: 15,000,000 and «Permafrost Landscape Map of the Republic of Sakha (Yakutia)» at a scale of 1: 1,500,000, is presented, as well as their use as a basis for environmental planning and geoecological assessment.