Torsion free groups with indecomposable holonomy group I

We study the torsion free generalized crystallographic groups with the indecomposable holonomy group which is isomorphic to either a cyclic group of order ${p^s}$ or a direct product of two cyclic groups of order ${p}$.Comment: 22 pages, AMS-Te

Pneumomediastinum as a predictor of negative prognosis in patients with coronavirus pneumonia

Aim of the study was to analyze the course of coronavirus pneumonia in patients with pneumomediastinum. Material and methods. The study included 139 patients, 71 of whom developed spontaneous pneumomediastinum against the background of coronavirus pneumonia. Laboratory, clinical and radiological data were analyzed and compared. Results. The relationship between the severity of viral pneumonia (3rd–4th degree of severity according to MSCT) and pneumomediastinum was revealed. It was found that spontaneous mediastinal emphysema in patients with COVID-19 signifcantly more often leads to the development of acute respiratory distress syndrome, multiple organ failure and can be a predictor of negative prognosis of the disease outcome. Conclusions. Pneumomediastinum in patients with viral pneumonia caused by a new coronavirus infection is a predictor of severe disease and poor prognosis. With an increase in spontaneous mediastinal emphysema without pneumothorax, it is recommended to perform mediastinotomy according to Razumovsky’s indications, and in case of clinically signifcant concomitant pneumothorax – drainage and revision of the mediastinum

An Open Resource for Non-human Primate Imaging.

Non-human primate neuroimaging is a rapidly growing area of research that promises to transform and scale translational and cross-species comparative neuroscience. Unfortunately, the technological and methodological advances of the past two decades have outpaced the accrual of data, which is particularly challenging given the relatively few centers that have the necessary facilities and capabilities. The PRIMatE Data Exchange (PRIME-DE) addresses this challenge by aggregating independently acquired non-human primate magnetic resonance imaging (MRI) datasets and openly sharing them via the International Neuroimaging Data-sharing Initiative (INDI). Here, we present the rationale, design, and procedures for the PRIME-DE consortium, as well as the initial release, consisting of 25 independent data collections aggregated across 22 sites (total = 217 non-human primates). We also outline the unique pitfalls and challenges that should be considered in the analysis of non-human primate MRI datasets, including providing automated quality assessment of the contributed datasets

Logistical analysis of the littoral combat ship

The purpose of the Littoral Combat Ship is to provide the Navy with an affordable, small, multi-mission ship capable of independent, interdependent and integrated operations inside the littorals. The Littoral Combat Ship will be designed to replace high-value Naval assets when conducting high-end missions such as littoral Anti-Submarine Warfare (ASW), Mine Warfare (MIW) and Anti-Surface Warfare (ASuW) as well as perform low-end missions such as Humanitarian Assistance (HA), Non-combatant Evacuation Operations (NEO) and Maritime Intercept Operations (MIO). In order to accomplish these missions and successfully counter the enemy's littoral denial strategy, the Navy has stated the Littoral Combat Ship must incorporate endurance, speed, payload capacity, sea-keeping, shallow-draft and mission reconfigurability into a small ship design. However, constraints in current ship design technology make this desired combination of design characteristics in small ships difficult to realize at any cost. This thesis (1) analyzes the relationship between speed, endurance, and payload to determine the expected displacement of the Littoral Combat Ship, (2) determines the impact of speed, displacement and significant wave height on Littoral Combat Ship fuel consumption and endurance, and (3) analyzes the implication of findings on Littoral Combat Ship logistics.http://archive.org/details/logisticalnalysi109451069Lieutenant Commander, Supply Corps, United States Naval ReserveApproved for public release; distribution is unlimited

Stability of Baroclinic Vortices on the β Plane and Implications for Transport

Abstract This paper explores stability of and transport by baroclinic vortices on the β plane using a two-layer, quasigeostrophic model. The study adapts a wave–mean flow formalism and examines interactions between the axisymmetric flow (“the vortex”) and residuals (“the waves”). Unlike baroclinically unstable vortices on the f plane, such vortices on the β plane can be also vulnerable to barotropic instability as revealed by the globally integrated energy balance analysis. The spatial structure of energy fluxes shows the energy leakage inside the vortex core when its breakdown occurs. Mixing by stable and unstable vortical flows is quantified through the computation of finite-time Lyapunov exponent (FTLE) maps. Depending on the strength of wave radiation, the upper-layer FTLE maps of stable vortices show either an annulus or volute ring of vigorous mixing inside the vortex interior. This ring region is disrupted when the vortex becomes unstable. Both stable and unstable vortices show the wavy patterns of FTLE in the near and far fields. Despite the fact that the initial vortex resides in the top layer only, significant FTLE patterns are observed in the deep layer at later times. Lagrangian analysis of the vortex-induced change of large-scale tracer gradient demonstrates significant effects of vortex instability in the top layer and the importance of the wavelike anomalies in the bottom layer