Elastic moduli of sea ice and lake ice calculated from in-situ and laboratory experiments

The effective elastic modulus of ice is an important physical parameter for the calculation of ice stresses in different situations when ice deformations are small. In the present paper the review of methods used for the calculation of the elastic modulus of ice is performed, new tests for the calculation of the elastic modulus are described, and their results are discussed. Field experiments with floating vibrating ice beams with fixed ends were performed in March and November 2019 on sea ice of the Van Mijen Fjord and fresh-water ice of a lake near Longyearbyen. Laboratory experiments with vibrating cantilever beams were performed in the cold laboratory of UNIS in November 2019. The results are compared with the values of the effective elastic modulus obtained in quasi-static tests with floating cantilever beams, and with in-situ dynamic tests where the effective elastic modulus was measured by the speed of sound waves

Influence of vibrations on indentation and compression strength of sea ice

Indentation and compression strengths of floating sea ice subjected to vibrations is discussed. The experiments were performed on the land fast ice of the Van-Mijen Fjord in March of 2018 and 2019. The ice thickness was around 70 cm, and the ice salinity was 4-5 ppt. Vibrations were introduced in the ice by the vibration plate with weight of 400 kg before the tests during 10-15 min. The vibration plate was standing and vibrating on the ice surface. The spectrum of vibrations was recorded with accelerometers. Analysis of thin sections of ice was performed on the place of the field works. Indentation tests were performed with the original hydraulic rig on natural ice and ice subjected to the action of vibrating plate. It was discovered that stroke rates tests were higher in the tests performed on the ice subjected to vibrations. Uniaxial compression tests were also performed on ice cores taken from the natural ice and from the ice subjected to the vibrations. Uniaxial compression strength of ice cores taken from the ice subjected to vibrations was higher than in the tests with natural ice

Nodular Dermatitis: Emergence of Novel Poxviral Infection in Russia

Nodular dermatitis, (dermatitis nodularis), is an exotic for the Russian Federation poxviral disease. Some epizootical characteristics of it, problems of laboratory diagnostics, and possible reasons of extension of agent spread areal are discussed in this review. Phylogenetic analysis of P32 gene nucleotide sequences of dermatitis nodularis virus has also been conducted. It is noted that taking into account the economic loss caused by the disease and possibility of its import into non-enzootic regions, it is necessary to use existing effective means of specific prophylacsis extensively. The swift outspread of the disease in the Russian Federation should be considered as the risk factor for biological safety of our country

Systemic Immune Activation in HIV Infection Is Associated with Decreased MDC Responsiveness to TLR Ligand and Inability to Activate Naive CD4 T-Cells

HIV infection is characterized by ineffective anti-viral T-cell responses and impaired dendritic cell (DC) functions, including response to Toll-Like Receptor (TLR) ligands. Because TLR responsiveness may affect a host's response to virus, we examined TLR ligand induced Myeloid and Plasmacytoid DC (MDC and PDC) activation of naïve T-cells in HIV+ subjects.Freshly purified MDC and PDC obtained from HIV+ subjects and healthy controls were cultured in the presence and absence of TLR ligands (poly I∶C or R-848). We evaluated indices of maturation/activation (CD83, CD86, and HLA-DR expression), cytokine secretion (IFN-alpha and IL-6), and ability to activate allogeneic naïve CD4 T-cells to secrete IFN-gamma and IL-2.MDC from HIV+ subjects had increased spontaneous IL-6 production and increased CD83 and CD86 expression when compared to MDC of controls. MDC IL-6 expression was associated with plasma HIV level. At the same time, poly I∶C induced HLA-DR up-regulation on MDC was reduced in HIV+ persons when compared to controls. The latter finding was associated with impaired ability of MDC from HIV+ subjects to activate allogeneic naïve CD4 T-cells. PDC from HIV+ persons had increased spontaneous and TLR ligand induced IL-6 expression, and increased HLA-DR expression at baseline. The latter was associated with an intact ability of HIV PDC to activate allogeneic naïve CD4 T-cells.These results have implications for the ability of the HIV+ host to form innate and adaptive responses to HIV and other pathogens

Enumeration of Functional T-Cell Subsets by Fluorescence-Immunospot Defines Signatures of Pathogen Burden in Tuberculosis

IFN-γ and IL-2 cytokine-profiles define three functional T-cell subsets which may correlate with pathogen load in chronic intracellular infections. We therefore investigated the feasibility of the immunospot platform to rapidly enumerate T-cell subsets by single-cell IFN-γ/IL-2 cytokine-profiling and establish whether immunospot-based T-cell signatures distinguish different clinical stages of human tuberculosis infection.We used fluorophore-labelled anti-IFN-γ and anti-IL-2 antibodies with digital overlay of spatially-mapped colour-filtered images to enumerate dual and single cytokine-secreting M. tuberculosis antigen-specific T-cells in tuberculosis patients and in latent tuberculosis infection (LTBI). We validated results against established measures of cytokine-secreting T-cells.Fluorescence-immunospot correlated closely with single-cytokine enzyme-linked-immunospot for IFN-γ-secreting T-cells and IL-2-secreting T-cells and flow-cytometry-based detection of dual IFN-γ/IL-2-secreting T-cells. The untreated tuberculosis signature was dominated by IFN-γ-only-secreting T-cells which shifted consistently in longitudinally-followed patients during treatment to a signature dominated by dual IFN-γ/IL-2-secreting T-cells in treated patients. The LTBI signature differed from active tuberculosis, with higher proportions of IL-2-only and IFN-γ/IL-2-secreting T-cells and lower proportions of IFN-γ-only-secreting T-cells.Fluorescence-immunospot is a quantitative, accurate measure of functional T-cell subsets; identification of cytokine-signatures of pathogen burden, distinct clinical stages of M. tuberculosis infection and long-term immune containment suggests application for treatment monitoring and vaccine evaluation

The tensile strength of saline and freshwater ice in field tests

This paper presents the results of meso-scale (~1m) in-situ tests on the tensile strength of saline and freshwater floating ice. These results are directly comparable to previous small scale tests, in which the measured tensile strength of sea ice and fresh ice decreases from 1MPa to 0.2MPa as the temperature increases from -30C to -2C. The new experiments were performed in Svalbard, Norway, from 2013-16, on landfast ice in the Van Mijen Fjord, and on freshwater lake ice near Longyearbyen. Loads were applied in the horizontal direction over the entire ice thickness on pre-cut necks, described below. All meso-scale tests demonstrated brittle and synchronous failure of the necks by tension. Values of meso-scale tensile strength are typically around 0.1MPa

Migrant communities in Western European countries and in Russia: social demands and structural constraints

The study of communities formed by migrants is crucial for understanding the political communication in industrialized countries. There are three circumstances that actualize such a study. First, in countries with a long history of immigration, institutions of public representation of migrants have been developed to ensure the participation of the latter in the political life of the host societies. Secondly, migrants can form associations at the grassroots level to find common solutions without direct interaction with government institutions. Thirdly, migrants are often involved in the social and political life of the country of origin, as they maintain contact with organizations operating in their homeland. This connection is facilitated and intensified due to various online platforms. This paper provides an overview of current research on this topic, made in Western European countries, as well as the results of our own field research conducted in several Russian cities