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

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

Methylisothiazolinones elicit increased production of both T helper (Th)1- and Th2-like cytokines by peripheral blood mononuclear cells from contact allergic individuals

Background Delayed-type hypersensitivity reactions to nickel (Ni2+) in humans are associated with increased production of both T helper (Th) 1- and Th2-like cytokines. Cytokine responses to the major group of contact allergens, i.e. organic compounds, have been less extensively studied. We have investigated here the cytokine production induced by a mixture of methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI), the active ingredients in common preservatives that are capable of eliciting allergic contact dermatitis. Objective To characterize the immune response induced by MCI/MI in terms of the production of Th1- and Th2-like cytokines in peripheral blood mononuclear cells (PBMC) from allergic and non-allergic subjects. Methods Ten subjects with a history of contact allergy to MCI/MI and nine age-matched non-allergic volunteers participated. Their actual status was confirmed by patch testing. PBMC were cultured in the presence or absence of MCI/MI; cell proliferation was measured employing [H-3]thymidine incorporation; and the number of cytokine-producing cells was determined using the enzyme-linked immunospot (ELISpot) assay and the levels of soluble cytokines in culture media by the enzyme-linked immunosorbent assay (ELISA). Results The proliferative response of PBMC to MCI/MI was significantly greater in the case of the allergic group than for the non-allergic group, as was the production of interleukin (IL)-2 and IL-13 (as determined by ELISpot and/or ELISA). PBMC from three of the allergic individuals with increased production of IL-2 and IL-13 responded to MCI/MI with elevated numbers of cells producing IL-4 and IL-5. The increases in the production of IL-2, IL-4, IL-5 and IL-13 were positively correlated. Conclusion MCI/MI elicited concomitant production of both Th1- and Th2-like cytokines by PBMC from subjects with contact allergy to these substances. This finding indicates that the organic compounds MCI/MI elicit a mixed Th1- and Th2-type of response, similar to that elicited by the metal ion Ni2+ in Ni2+-sensitized individuals