The sub-crustal stress estimation in central Eurasia from gravity, terrain and crustal structure models

Robert Tenzer,Mehdi Eshagh,Wenbin Shen 한국지질과학협의회 2017 Geosciences Journal Vol.21 No.1

We investigate the horizontal stress field beneath crustal structures of central Eurasia. The numerical procedure applied for a simultaneous determination of the sub-crustal stress and the crustal thickness from the global gravity, terrain and crustal structure models is based on solving Navier-Stokes’ problem which incorporates the inverse solution to the Vening Meinesz- Moritz’s problem of isostasy. The numerical results reveal that a spatial distribution of the sub-crustal stress in this study area closely resembles the regional tectonic configuration comprising parts of the Eurasian, Indian and Arabian lithospheric plates. The maximum shear stress intensity is generated by a subduction of the Indian plate beneath the Tibetan block. The intra-plate tectonic configuration is marked by the stress anomalies distributed along major active strike-slip fault systems and sections of subduction which separate the Tibetan and Iranian blocks from the rest of the Eurasian plate. The most pronounced intra-plate stress anomalies are related with a subduction of the Eurasian plate beneath the Tibetan block. We also demonstrate that a prevailing convergent orientation of stress vectors agree with the compressional tectonism of orogenic formations (Himalaya and Tibet Plateau, Than Shan, Zargos and Iranian Plateau), while the extensional tectonism of continental basins (Tarim, Ganges-Brahmaputra, Sichuan) is manifested by a divergence of stress vectors.

Global model of the upper mantle lateral density structure based on combining seismic and isostatic models

Robert Tenzer,Mohammad Bagherbandi,Peter Vajda 한국지질과학협의회 2013 Geosciences Journal Vol.17 No.1

We compile the global model of the upper mantle lateral density structure with a 2x2 arc-deg spatial resolution using the values of the crust-mantle density contrast estimated relative to the adopted crust density model. The combined least-squares approach based on solving Moritz’s generalization of the Vening-Meinesz inverse problem of isostasy is facilitated to estimate the crust-mantle density contrast. The global geopotential model (EGM08), the global topographic/bathymetric model (DTM2006.0) including ice-thickness data, and the global crustal model (CRUST2.0) are used to compute the isostatic gravity anomalies. The estimated upper mantle densities globally vary between 2751 and 3635 kg/m3. The minima correspond with locations of the divergent oceanic tectonic plate boundaries (along the mid-oceanic ridges). The maxima are found along the convergent tectonic plate boundaries in the Andes and Himalayas (extending under the Tibetan Plateau). A comparison of the estimated upper mantle densities with the CRUST2.0 data shows a relatively good agreement between these two models within the continental lithosphere with the differences typically within ±100 kg/m3. Much larger discrepancies found within the oceanic lithosphere are explained by the overestimated values of the CRUST2.0 upper mantle densities. Our result shows a prevailing pattern of increasing densities with the age of oceanic lithosphere which is associated with the global mantle convection process.

Herpes virus entry mediator synergizes with Toll-like receptor mediated neutrophil inflammatory responses

Haselmayer, Philipp,Tenzer, Stefan,Kwon, Byoung S.,Jung, Gundram,Schild, Hansjö,rg,Radsak, Markus P. Blackwell Publishing Ltd 2006 Immunology Vol.119 No.3

<P>Summary</P><P>In microbial infections polymorphnuclear neutrophils (PMN) constitute a major part of the innate host defence, based upon their ability to rapidly accumulate in inflamed tissues and clear the site of infection from microbial pathogens by their potent effector mechanisms. The recently described transmembrane receptor herpes virus entry mediator (HVEM) is a member of the tumour necrosis factor receptor super family and is expressed on many haematopoietic cells, including T cells, B cells, natural killer cells, monocytes and PMN. Interaction of HVEM with the natural ligand LIGHT on T cells has a costimulatory effect, and increases the bactericidal activity of PMN. To further characterize the function of HVEM on PMN, we evaluated the effect of receptor ligation on human PMN effector functions using an agonistic monoclonal antibody. Here we demonstrate that activation of HVEM causes activation of neutrophil effector functions, including respiratory burst, degranulation and release of interleukin-8 in synergy with ligands for Toll-like receptors or GM-CSF. In addition, stimulation via HVEM enhanced neutrophil phagocytic activity of complement opsonized, but not of non-opsonized, particles. In conclusion, these results indicate a new, as yet unknown, participation of HVEM in the innate immune response and points to a new link between innate and adaptive immunity.</P>

Empirical models of the ocean-sediment and marine sediment-bedrock density contrasts

Xiang Gu,Robert Tenzer,Vladislav Gladkikh 한국지질과학협의회 2014 Geosciences Journal Vol.18 No.4

We utilize empirical density models of the seawater,marine sediments and bedrock to evaluate the ocean-sediment and(marine) sediment-bedrock density contrasts. The depth-dependentseawater density model and a density model of the upper sedimentarylayer are used in computing the ocean-sediment densitycontrast. A definition of the sediment-bedrock density contrast withrespect to the average bedrock density is based on applying themarine sediment density model. Density samples from the Deep SeaDrilling Project are used to establish the density model of marinesediments and to estimate the average bedrock density. The marinesediment density model describes the density distribution within theupper sedimentary layer as a function of the ocean-floor depth, whilethe increasing sediment density due to compaction is defined as afunction of the sediment depth. The depth-dependent seawaterdensity model was derived based on the analysis of oceanographicdata from the World Ocean Atlas 2009 and the World Ocean CirculationExperiment 2004. The predicted values of both densitycontrasts are compiled on a 5 × 5 arc-min geographical grid for theworld’s oceans and marginal seas. The ocean-sediment densitycontrast varies between 0.05 and 0.63 g/cm3. The maximum densitycontrast is predicted beneath marginal seas due to the accumulationof heavier sediments near coast. Transportation of fine and lightparticles at long distances results in decreasing density contrastbetween the seawater and the underlying deep-ocean sediments. The sediment-bedrock density contrast varies between 0.00 and1.70 g/cm3. The most enhanced density contrast between the marinesediments and the underlying bedrock is predicted beneath thinsedimentary layers, while the density at the lowermost stratigraphicunits of thick sedimentary accumulations is similar to the bedrockdensity due to sediment compaction (and further lithification).

The THESEUS space mission concept: science case, design and expected performances

Amati, L.,O’Brien, P.,Gö,tz, D.,Bozzo, E.,Tenzer, C.,Frontera, F.,Ghirlanda, G.,Labanti, C.,Osborne, J.P.,Stratta, G.,Tanvir, N.,Willingale, R.,Attina, P.,Campana, R.,Castro-Tirado, A.J.,Contini, Elsevier 2018 ADVANCES IN SPACE RESEARCH Vol.62 No.1

<P><B>Abstract</B></P> <P>THESEUS is a space mission concept aimed at exploiting Gamma-Ray Bursts for investigating the early Universe and at providing a substantial advancement of multi-messenger and time-domain astrophysics. These goals will be achieved through a unique combination of instruments allowing GRB and X-ray transient detection over a broad field of view (more than 1sr) with 0.5–1 arcmin localization, an energy band extending from several MeV down to 0.3 keV and high sensitivity to transient sources in the soft X-ray domain, as well as on-board prompt (few minutes) follow-up with a 0.7 m class IR telescope with both imaging and spectroscopic capabilities. THESEUS will be perfectly suited for addressing the main open issues in cosmology such as, e.g., star formation rate and metallicity evolution of the inter-stellar and intra-galactic medium up to redshift ∼ 10, signatures of Pop III stars, sources and physics of re-ionization, and the faint end of the galaxy luminosity function. In addition, it will provide unprecedented capability to monitor the X-ray variable sky, thus detecting, localizing, and identifying the electromagnetic counterparts to sources of gravitational radiation, which may be routinely detected in the late ’20s/early ’30s by next generation facilities like aLIGO/ aVirgo, eLISA, KAGRA, and Einstein Telescope. THESEUS will also provide powerful synergies with the next generation of multi-wavelength observatories (e.g., LSST, ELT, SKA, CTA, ATHENA).</P>