Screening Polarimetric SAR Data via Geometric Barycenters for Covariance Symmetry Classification

This letter proposes a robust framework for polarimetric covariance symmetries classification in Synthetic Aperture Radar (SAR) images applying a pre-screening on the data looks before they are used to perform inferences. More specifically, the devised method improves the performance of a previous work based on the exploitation of the special structures assumed by the covariance/coherence matrix when symmetric scattering mechanisms dominate the polarimetric returns. To do this, the algorithm selects first the most homogeneous data through the cancellation of those sharing the highest Generalized Inner Product (GIP) values computed with the use of the geometric barycenters. Then, the procedure based on Model Order Selection (MOS) developed in the homogeneous case is applied on the filtered data. The conducted tests show the potentiality of the proposed method in correctly classifying the observed scene of L-band real-recorded SAR data with respect to its standard counterpart

EuCRUST-07: A new reference model for the European crust

We present a new digital model ( EuCRUST-07) for the crust of Western and Central Europe and surroundings ( 35 degrees N - 71 degrees N, 25 degrees W - 35 degrees E). Available results of seismic reflection, refraction and receiver functions studies are assembled in an integrated model at a uniform grid ( 15 ' x 15 '). The model consists of three layers: sediments and two layers of the crystalline crust. Besides depth to the boundaries, we provide average P-wave velocities in the upper and lower parts of the crystalline crust. The new model demonstrates large differences in the Moho depth compared to previous compilations, over +/- 10 km in some specific areas ( e. g. the Baltic Shield). Furthermore, the velocity structure of the crust is much more heterogeneous than in previous maps. EuCRUST-07 offers a starting point for numerical modeling of deeper structures by allowing correction for crustal effects beforehand and to resolve trade-off with mantle heterogeneities

increased endothelin 1 mediated vasoconstrictor tone in human obesity effects of gut hormones

The heavy impact of obesity on the development and progression of cardiovascular disease has sparked sustained efforts to uncover the mechanisms linking excess adiposity to vascular dysfunction. Impaired vasodilator reactivity has been recognized as an early hemodynamic abnormality in obese patients, but also increased vasoconstrictor tone importantly contributes to their vascular damage. In particular, upregulation of the endothelin (ET)-1 system, consistently reported in these patients, might accelerate atherosclerosis and its complication, given the pro-inflammatory and mitogenic properties of ET-1. In recent years, a number of gut hormones, in addition to their role as modulators of food intake, energy balance, glucose and lipid metabolism, and insulin secretion and action, have demonstrated favorable vascular actions. They increase the bioavailability of vasodilator mediators like nitric oxide, but they have also been shown to inhibit the ET-1 system. These features make gut hormones promising tools for targeting both the metabolic and cardiovascular complications of obesity, a view supported by recent large-scale clinical trials indicating that novel drugs for type 2 diabetes with cardiovascular potential may translate into clinically significant advantages. Therefore, there is real hope that better understanding of the properties of gut-derived substances might provide more effective therapies for the obesity-related cardiometabolic syndrome

An integrated study of the structure and thermomechanical properties of the European lithosphere

Cloetingh, S.A.P.L. [Promotor]Beekman, W.W.W. [Copromotor]Kaban, M.K. [Copromotor

Supercontinent-paced magmatic destabilisation and recratonisation of the Yilgarn Craton

Knowledge of the evolution of ancient cratonic lithospheres underpins our understanding of Precambrian Earth. The Yilgarn Craton has exceptionally well-preserved Archean geology, with juvenile crust formation and major orogenesis concluding in the Neoarchean, and a stabilised upper-crustal architecture developing before 2.42 Ga. However, in an apparent dichotomy, geophysical models resolve lithospheric mantle composition outside the range of xenolith data from Archean regions, indicating the lithospheric mantle has since been extensively refertilised. Post-Archean igneous and sedimentary rocks record a prolonged lithospheric evolution that is not well resolved in datasets recording bulk crustal isotopic evolution. Reconciling these, we combine interpretation of geological and geophysical data to resolve two phases of lithosphere destabilisation driven by major magmatic events at ∼2.06 Ga and at ∼1.08 Ga. During destabilisation, sub-lithospheric and sub-crustal mantle fluxes caused extensive mantle refertilisation. For 200–400 Ma post-refertilisation, distributed sedimentary basins formed during recratonisation of the now denser lithosphere. The timing of these events suggests a relationship with the early stages of supercontinent assembly: Dominant downwelling beneath the assembling supercontinent sustains a sufficiently non-tensile tectonic setting to inhibit lithospheric thinning and breakup and enhances lateral flow of any upwelling mantle. This setting allows widespread intraplate refertilisation to occur while later the assembled supercontinent provides a stable setting allowing thermal re-equilibration and recratonisation to occur. In contrast, lithospheric refertilisation during supercontinent breakup will be more susceptible to density instabilities and recycling in later collisions. Consequently, we suggest that refertilisation of extant cratonic lithosphere may dominantly have occurred during the assembly of supercontinents

Generation of large scale digital evaluation models via synthetic aperture radar interferometry

We investigate the possibility to generate a large-scale Digital Elevation Model by applying the Synthetic Aperture Radar interferometry technique and using tandem data acquired by the ERS-1/ERS-2 sensors. The presented study is mainly focused on the phase unwrapping step that represents the most critical point of the overall processing chain. In particular, we concentrate on the unwrapping problems related to the use of a large ERS tandem data set that, in order to be unwrapped, must be partitioned. The paper discusses the inclusion of external information (even rough) of the scene topography, the application of a region growing unwrapping technique and the insertion of possible constraints on the phase to be retrieved in order to minimize the global unwrapping errors. Our goal is the generation of a digital elevation model relative to an area of 300 km by 100km located in the southern part of Italy. Comparisons between the achieved result and a precise digital terrain model, relative to a smaller area, are also included

A Thermo-Compositional Model of the African Cratonic Lithosphere

Recently, the continually increasing availability of seismic data has allowed high-resolution imaging of lithospheric structure beneath the African cratons. In this study, S-wave seismic tomography is combined with high resolution satellite gravity data in an integrated approach to investigate the structure of the cratonic lithosphere of Africa. A new model for the Moho depth and data on the crustal density structure is employed along with global dynamic models to calculate residual topography and mantle gravity residuals. Corrections for thermal effects of an initially juvenile mantle are estimated based on S-wave tomography and mineral physics. Joint inversion of the residuals yields necessary compositional adjustments that allow to recalculate the thermal effects. After several iterations, we obtain a consistent model of upper mantle temperature, thermal and compositional density variations, and Mg# as a measure of depletion, as well as an improved crustal density model. Our results show that thick and cold depleted lithosphere underlies West African, northern to central eastern Congo, and Zimbabwe Cratons. However, for most of these regions, the areal extent of their depleted lithosphere differs from the respective exposed Archean shields. Meanwhile, the lithosphere of Uganda, Tanzania, most of eastern and southern Congo, and the Kaapvaal Craton is thinner, warmer, and shows little or no depletion. Furthermore, the results allow to infer that the lithosphere of the exposed Archean shields of Congo and West African cratons was depleted before the single blocks were merged into their respective cratons

Interaction of Cisplatin with a CCHC Zinc Finger Motif

The interaction between cisplatin and an 18-residue CCHC zinc finger motif derived from a retroviral nucleocapsid protein (PyrZf18) has been studied using UV–visible, CD and 1H NMR spectroscopies and ESI-MS spectrometry. Cisplatin irreversibly blocks the cysteine zinc binding groups in the free peptide and is able to slowly eject zinc from the zinc–peptide complex. The observed end product of the reaction with cisplatin is a complex in which only one ammonia molecule is coordinated to platinum. After an initial binding with two cysteine residues and the formation of the (PyrZf18)– platinum–(NH3)2 complex, a release of one ammonia molecule occurs because of trans-labilization, and the third cysteine is coordinated, leading to a mixture of isomers and/or conformers of the (PyrZf18)–platinum–NH3 complex. The results are discussed with respect to the potential antiretroviral activity of platinum(II) compounds and to the possible interaction of cisplatin with the cellular nucleic acid binding proteins

Defect Dynamics for Spiral Chaos in Rayleigh-Benard Convection

A theory of the novel spiral chaos state recently observed in Rayleigh-Benard convection is proposed in terms of the importance of invasive defects i.e defects that through their intrinsic dynamics expand to take over the system. The motion of the spiral defects is shown to be dominated by wave vector frustration, rather than a rotational motion driven by a vertical vorticity field. This leads to a continuum of spiral frequencies, and a spiral may rotate in either sense depending on the wave vector of its local environment. Results of extensive numerical work on equations modelling the convection system provide some confirmation of these ideas.Comment: Revtex (15 pages) with 4 encoded Postscript figures appende