STATISTICAL STUDY OF STRONG AND EXTREME GEOMAGNETIC DISTURBANCES AND SOLAR CYCLE CHARACTERISTICS

We study the relation between strong and extreme geomagnetic storms and solar cycle characteristics. The analysis uses an extensive geomagnetic index AA data set spanning over 150 yr. complemented by the Kakioka magnetometer recordings. We apply Pearson correlation statistics and estimate the significance of the correlation with a bootstrapping technique. We show that the correlation between the storm occurrence and the strength of the solar cycle decreases from a clear positive correlation with increasing storm magnitude toward a negligible relationship. Hence, the quieter Sun can also launch superstorms that may lead to significant societal and economic impact. Our results show that while weaker storms occur most frequently in the declining phase, the stronger storms have the tendency to occur near solar maximum. Our analysis suggests that the most extreme solar eruptions do not have a direct connection between the solar large-scale dynamo-generated magnetic field, but are rather associated with smaller-scale dynamo and resulting turbulent magnetic fields. The phase distributions of sunspots and storms becoming increasingly in phase with increasing storm strength, on the other hand, may indicate that the extreme storms are related to the toroidal component of the solar large-scale field.Peer reviewe

Joint inflammation related citrullination of functional arginines in extracellular proteins

We report the extent, specific sites and structural requirements of joint inflammation related citrullination in extracellular proteins. A total of 40 synovial fluid samples derived from chronically inflamed human joints were analysed by heparin-agarose fractionation and LC-MS/MS. Citrullination of 55 arginines in extracellular proteins was detected. Importantly, 20% of the sites have a characterized function related to the hallmarks of destructive joint inflammation. E.g. four arginine residues, shown here to be citrullinated, are also affected by mutations in inherited diseases causing haemolysis or blood clotting dysfunction. Citrullination of integrin ligands was selected for further studies since fibronectin R234 in isoDGR was among the most frequently citrullinated arginines in synovial fluid. Assays with synovial fibroblasts and integrin alpha V beta 3 indicated decreased affinity to the enzymatically citrullinated integrin binding sites. To conclude, our data indicate that in inflamed joints extensive citrullination affects the functional arginine residues in extracellular proteins

Stellar Dynamos in the Transition Regime

| openaire: EC/H2020/730897/EU//HPC-EUROPA3 | openaire: EC/H2020/818665/EU//UniSDynGlobal and semi-global convective dynamo simulations of solar-like stars are known to show a transition from an antisolar (fast poles, slow equator) to solar-like (fast equator, slow poles) differential rotation (DR) for increasing rotation rate. The dynamo solutions in the latter regime can exhibit regular cyclic modes, whereas in the former one, only stationary or temporally irregular solutions have been obtained so far. In this paper we present a semi-global dynamo simulation in the transition region, exhibiting two coexisting dynamo modes, a cyclic and a stationary one, both being dynamically significant. We seek to understand how such a dynamo is driven by analyzing the large-scale flow properties (DR and meridional circulation) together with the turbulent transport coefficients obtained with the test-field method. Neither an ??dynamo wave nor an advection-dominated dynamo are able to explain the cycle period and the propagation direction of the mean magnetic field. Furthermore, we find that the ? effectis comparable or even larger than the ? effect in generating the toroidal magnetic field, and therefore, the dynamo seems to be of ?(2)? or ?(2) type. We further find that the effective large-scale flows are significantly altered by turbulent pumping.Peer reviewe

Leukocyte integrins alpha(L)beta(2), alpha(M)beta(2) and alpha(X)beta(2) as collagen receptors - Receptor activation and recognition of GFOGER motif

Integrins alpha(L)beta(2), alpha(M)beta(2) and alpha(X)beta(2) are expressed on leukocytes. Their primary ligands are counter transmembrane receptors or plasma proteins, such as intercellular cell adhesion molecule-1 (ICAM-1) or components of complement system (iC3b, iC4b), respectively. Function blocking antibodies for these integrins may also reduce cell adhesion to collagens. To make the first systematical comparison of human alpha(L)beta(2), alpha(M)beta(2) and alpha(X)beta(2) as collagen receptors, we produced the corresponding integrin alpha I domains both in wild-type and activated form and measured their binding to collagens I-VI. In the &quot;closed&quot; (wild-type) conformation, the alpha I-L and alpha I-M domains bound with low avidity to their primary ligands, and the interaction with collagens was also very weak. Gain-of-function mutations alpha(L) I306G, alpha(L) K287C/K294C and alpha(M) I316G are considered to mimic &quot;open&quot;, activated alpha I domains. The binding of these activated alpha I domains to the primary ligands was clearly stronger and they also recognized collagens with moderate avidity (K-d &lt; 400 nM). After activation, the alpha I-L domain favored collagen I (K-d approximate to 0 nM) when compared to collagen IV. The integrin alpha I-X domain acted in a very different manner since already in native, wild-type form it bound to collagen IV and iC3b (K-d approximate to 200-400 nM). Antibodies against alpha(X)beta(2) and alpha(M)beta(2) blocked promyelocytic leukemia cell adhesion to the collagenous GFOGER motif, a binding site for the beta(1) integrin containing collagen receptors. In brief, leukocyte beta(2) integrins may act as collagen receptors in a heterodimer specific manner. (C) 2013 Elsevier Ltd. All rights reserved.</p