Three-dimensional geometry, ore distribution and time-integrated mass transfer through the quartz-tourmaline-gold vein network of the Sigma deposit (Abitibi belt, Canada)

We present a reconstruction of the three-dimensional (3D) geometry and gold grade distribution of shear zone-hosted, Au-mineralized, quartz-tourmaline veins of the Sigma deposit (Abitibi belt). Host shears and veins form a network of anastomosing, steeply dipping structures associated with smaller subhorizontal extensional veins. Our reconstruction has been carried out using the exceptionally large geological database of the mine. From this database, we extracted the geometric position, thickness and gold grades of geometrically best-defined steep veins contained in a representative subvolume of the deposit. These data allowed the 3D representation of 53 veins, which have been constructed by fitting surfaces through the geometrical data and by contouring thickness and gold grade. The geometry of the network is mainly characterized by: (i) a few large segmented veins, with sinuous and helicoidal shape, and typical vertical dimension of >100 m; (ii) a large number of smaller vertical veins, some of which splay off the steep veins with high dip angles; (iii) subhorizontal extension veins (joints) located at, or close to, the tips of steep veins. The absolute thickness of the vertically short veins is the same as that of the large veins, suggesting that they formed simultaneously, but only a few of them interconnect to form vertically continuous bodies. Patchy, vertically elongated zones of high dilation are present in the large veins, and are poorly correlated with Au-rich zones. They presumably represent former high-permeability zones of the network. The highest gold grades occur at the interconnections between the large veins and small splays or subhorizontal joints. This indicates the important role of vein interconnection for fluid flow and gold precipitation within the network. Combining the calculation of the volume of the network with the estimation of tourmaline abundance in the veins, we calculate that 2.1 × 106 m3 of tourmaline and 3.2 × 106 m3 of quartz precipitated during Au deposition

Nonlinear diffusion & thermo-electric coupling in a two-variable model of cardiac action potential

This work reports the results of the theoretical investigation of nonlinear dynamics and spiral wave breakup in a generalized two-variable model of cardiac action potential accounting for thermo-electric coupling and diffusion nonlinearities. As customary in excitable media, the common Q10 and Moore factors are used to describe thermo-electric feedback in a 10-degrees range. Motivated by the porous nature of the cardiac tissue, in this study we also propose a nonlinear Fickian flux formulated by Taylor expanding the voltage dependent diffusion coefficient up to quadratic terms. A fine tuning of the diffusive parameters is performed a priori to match the conduction velocity of the equivalent cable model. The resulting combined effects are then studied by numerically simulating different stimulation protocols on a one-dimensional cable. Model features are compared in terms of action potential morphology, restitution curves, frequency spectra and spatio-temporal phase differences. Two-dimensional long-run simulations are finally performed to characterize spiral breakup during sustained fibrillation at different thermal states. Temperature and nonlinear diffusion effects are found to impact the repolarization phase of the action potential wave with non-monotone patterns and to increase the propensity of arrhythmogenesis

Obesity hormone leptin: a new target in breast cancer?

Leptin is a multifunctional hormone produced mainly by the adipose tissue and involved in the regulation of food intake and energy balance. In addition, leptin can stimulate mitogenic and angiogenic processes in peripheral organs. Because leptin levels are elevated in obese individuals and excess body weight has been shown to increase breast cancer risk in postmenopausal women, attempts have been made to evaluate whether leptin can promote breast cancer. Data obtained in cell and animal models and analyses of human breast cancer biopsies indeed suggest such an involvement. Furthermore, a recent report clearly shows that targeting leptin signaling may reduce mammary carcinogenesis. Thus, leptin should become a new attractive target in breast cancer

Trapping of magnetic flux by the plunge region of a black hole accretion disk

The existence of the radius of marginal stability means that accretion flows around black holes invariably undergo a transition from a MHD turbulent disk-like flow to an inward plunging flow. We argue that the plunging inflow can greatly enhance the trapping of large scale magnetic field on the black hole, and therefore may increase the importance of the Blandford-Znajek (BZ) effect relative to previous estimates that ignore the plunge region. We support this hypothesis by constructing and analyzing a toy-model of the dragging and trapping of a large scale field by a black hole disk, revealing a strong dependence of this effect on the effective magnetic Prandtl number of the MHD turbulent disk. Furthermore, we show that the enhancement of the BZ effect depends on the geometric thickness of the accretion disk. This may be, at least in part, the physical underpinnings of the empirical relation between the inferred geometric thickness of a black hole disk and the presence of a radio jet.Comment: 18 pages, 3 figures, accepted for publication in the Astrophysical Journal. See http://www.astro.umd.edu/~chris/publications/movies/flux_trapping.html for animation

Closing the loop of SIEM analysis to Secure Critical Infrastructures

Critical Infrastructure Protection is one of the main challenges of last years. Security Information and Event Management (SIEM) systems are widely used for coping with this challenge. However, they currently present several limitations that have to be overcome. In this paper we propose an enhanced SIEM system in which we have introduced novel components to i) enable multiple layer data analysis; ii) resolve conflicts among security policies, and discover unauthorized data paths in such a way to be able to reconfigure network devices. Furthermore, the system is enriched by a Resilient Event Storage that ensures integrity and unforgeability of events stored

Trace Metals in Pork Meat Products Marketed in Italy: Occurrence and Health Risk Characterization

This study provides valuable information on the levels of various trace metals (Pb, Cd, Hg, Zn, Cu, Cr) in meat products (baked ham, raw ham, mortadella, cured sausage, würstel, salami) from South Italy and calculates potential health risk toxicity associated with their consumption for the total population and for children. In the samples studied metal concentrations are within the permissible legal limits (Cd: 0.01–0.03 μg g−1 w.w., Hg: 0.01–0.02 μg g−1 w.w., Zn: 5.71–7.32 μg g−1 w.w., Cu: 1.08–1.21 μg g−1 w.w., Cr: 0.15–0.23 μg g−1 w.w.), except for Pb (Pb: 0.22–0.38 μg g−1 w.w.). The estimated intake values are within the provisional tolerable daily intake limits for toxic metals and recommended daily intake values for essential metals in both tested groups. The noncarcinogenic risk values of the individual metals indicate that there is no health risk, but their combined effects might constitute a potential risk for children. Furthermore, the cumulative cancer risk of all samples studied exceeds the recommended threshold risk limit (> 10−4) in both total population and children, indicating a risk of potential health problems for consumers especially for children, who are more vulnerable to toxic metal exposure

Translation error clusters induced by aminoglycoside antibiotics

Aminoglycoside antibiotics target the ribosome and induce mistranslation, yet which translation errors induce bacterial cell death is unclear. The analysis of cellular proteins by quantitative mass spectrometry shows that bactericidal aminoglycosides induce not only single translation errors, but also clusters of errors in full-length proteins in vivo with as many as four amino acid substitutions in a row. The downstream errors in a cluster are up to 10,000-fold more frequent than the first error and independent of the intracellular aminoglycoside concentration. The prevalence, length, and composition of error clusters depends not only on the misreading propensity of a given aminoglycoside, but also on its ability to inhibit ribosome translocation along the mRNA. Error clusters constitute a distinct class of misreading events in vivo that may provide the predominant source of proteotoxic stress at low aminoglycoside concentration, which is particularly important for the autocatalytic uptake of the drugs