Poroelastic Modelling of Wavefields in Heterogeneous Media. Poroelastische Modellierung von Wellenfeldern in Heterogenen Medien

Numerical modelling of seismic waves in heterogeneous, porous reservoir rocks is an important tool in the field of reservoir engineering. A new 2-D velocity-stress finite-differences scheme is presented that allows to simulate waves and coupled diffusion processes within poroelastic media as described by Biot theory. The presented numerical methods allow to further develop rock physics theories of wave-induced fluid flow and contribute to the interpretation of new laboratory experiments

As Rivers Run Dry: A Study of Global Freshwater Scarcity and Its Implications for Socio-Economic Development

Water scarcity is a serious problem—without adequate supplies of clean freshwater, there cannot be life. The direct and indirect costs of water scarcity are huge, including poor public health, gender inequality, and acute restrictions for economic development. Currently, around 20 percent of the global population lacks access to safe drinking water and 2.4 billion people do not have access to adequate sanitation facilities (UNEP Brief, 1). About 1.8 million people—most of them children less than five years old—die every year due to water-borne diseases from fecal pollution—the equivalent of about 15 killer tsunamis each year or 12 Boeing 747 crashes every day (1). The problem of water scarcity—the lack of a minimum supply of clean, fresh water where it is vitally needed to support human health, sustainable food production and fundamental ecological well-being—is not an issue simply for environmental activists, for it is fundamentally an issue of economics. Human health, economic development and ecological well-being all depend on the availability of clean freshwater. Water scarcity is caused by a variety of human and non-human factors: geography, population growth, high demand, pollution, deforestation, poor governance and climate change. Climate change, in particular, has the potential to greatly exacerbate the problems associated with water scarcity. Scarcity also threatens peaceful cooperation in regions with high levels of pre-existing tensions, and also threatens the realization of the United Nations’ Millennium Development Goals. Although water scarcity threatens security under certain circumstances, full-scale “water wars” are unlikely. Strong, integrated systems of water management have the potential to prevent and mitigate situations of water scarcity. Although the problem of water scarcity is nuanced and complex, there are a number of practical solutions that can easily, effectively and inexpensively diminish the problem

Perlecan-Induced Suppression of Smooth Muscle Cell Proliferation Is Mediated Through Increased Activity of the Tumor Suppressor PTEN

We were interested in the elucidation of the interaction between the heparan sulfate proteoglycan, perlecan, and PTEN in the regulation of vascular smooth muscle cell (SMC) growth. We verified serum-stimulated DNA synthesis, and Akt and FAK phosphorylation were significantly reduced in SMCs overexpressing wild-type PTEN. Our previous studies showed perlecan is a potent inhibitor of serum-stimulated SMC growth. We report in the present study, compared with SMCs plated on fibronectin, serum-stimulated SMCs plated on perlecan exhibited increased PTEN activity, decreased FAK and Akt activities, and high levels of p27, consistent with SMC growth arrest. Adenoviral-mediated overexpression of constitutively active Akt reversed perlecan-induced SMC growth arrest while morpholino antisense-mediated loss of endogenous PTEN resulted in increased growth and phosphorylation of FAK and Akt of SMCs on perlecan. Immunohistochemical and Western analyses of balloon-injured rat carotid artery tissues showed a transient increase in phosphoPTEN (inactive) after injury, correlating to high rates of neointimal cell replication; phosphoPTEN was largely limited to actively replicating SMCs. Similarly, in the developing rat aorta, we found increased PTEN activity associated with increased perlecan deposition and decreased SMC replication rates. However, significantly decreased PTEN activity was detected in aortas of perlecan-deficient mouse embryos, consistent with SMC hyperplasia observed in these animals, compared with E17.5 heterozygous controls that produce abundant amounts of perlecan at this developmental time point. Our data show PTEN is a potent endogenously produced inhibitor of SMC growth and increased PTEN activity mediates perlecan-induced suppression of SMC proliferation.Costell Rossello, M.Mercedes, [email protected]

Direct laboratory observation of patchy saturation and its effects on ultrasonic velocities

Maximizing the recovery of known hydrocarbon reserves is one of the biggest challenges facing the petroleum industry today. Optimal production strategies require accurate monitoring of production-induced changes of reservoir saturation and pressure over the life of the field. Time-lapse seismic technology is increasingly used to map these changes in space and time. However, until now, interpretation of time-lapse seismic data has been mostly qualitative. In order to allow accurate estimation of the saturation, it is necessary to know the quantitative relationship between fluid saturation and seismic characteristics (elastic moduli, velocity dispersion, and attenuation). The problem of calculating acoustic properties of rocks saturated with a mixture of two fluids has attracted considerable interest (Gist, 1994; Mavko and Nolen-Hoeksema, 1994; Knight et al., 1998. For a comprehensive review of theoretical and experimental studies of the patchy saturation problem see Toms et al., 2006)

Novel enzyme-linked immunosorbent assay for bivalent ZnT8 autoantibodies

Autoantibodies to zinc transporter 8 (ZnT8A) are a powerful diagnostic or predictive marker in type 1 diabetes. However, the widely used current ZnT8A radioligand binding assay (RBA) has proved to be difficult for many laboratories to implement. The aim of this study was the development and characterization of the performance of a novel fluid-phase ZnT8A enzyme-linked immunosorbent assay (ELISA) in relation to standard RBA in type 1 diabetes. Sera from 114 patients with type 1 diabetes and 140 blinded Islet Autoantibody Standardization Program (IASP2012) samples were studied. The sensitivity of ELISA-ZnT8A is equivalent to or slightly higher than that of conventional RBA with similar specificity. Furthermore, the median SD score using this ELISA was significantly higher than that obtained with RBA (P < 0.0001). Multiple logistic regression analysis revealed that ELISA-ZnT8A positivity was associated with younger age of onset (?20 years; OR 15.91, P = 0.0002), acute-onset form of type 1 diabetes (OR 3.38, P = 0.019), and the presence of IA-2 autoantibodies (OR 3.75, P = 0.014). Furthermore, the levels of ELISA-ZnT8A were associated with the reactivity to ZnT8-325Arg, but not ZnT8-325Trp. We conclude that this nonradioactive bivalent ZnT8A assay has high performance and should facilitate large-scale autoantibody screening. Moreover, these results suggest that the humoral autoimmunity against ZnT8 is related to a high risk of faster development of type 1 diabetes and the ZnT8A levels are associated with the known aa325 variants

Frequency-dependent anisotropy of porous rocks with aligned fractures

Naturally fractured reservoirs are becoming increasingly important for oil and gas exploration in many areas of the world. Because fractures may control the permeability of a reservoir, it is important to be able to find and characterize fractured zones. In fractured reservoirs, the wave-induced fluid flow between pores and fractures can cause significant dispersion and attenuation of seismic waves. For waves propagating normal to the fractures, this effect has been quantified in earlier studies. Here we extend normal incidence results to oblique incidence using known expressions for the stiffness tensors in the low- and high-frequency limits. This allows us to quantify frequency-dependent anisotropy due to the wave-induced flow between pores and fractures and gives a simple recipe for computing phase velocities and attenuation factors of quasi-P and SV waves as functions of frequency and angle. These frequency and angle dependencies are concisely expressed through dimensionless velocity anisotropy and attenuation anisotropy parameters. It is found that, although at low frequencies, the medium is close to elliptical (which is to be expected as a dry medium containing a distribution of penny-shaped cracks is known to be close to elliptical); at high frequencies, the coupling between P-wave and SV-wave results in anisotropy due to the non-vanishing excess tangential compliance