Time-lapse capacitive resistivity imaging: a new technology concept for the monitoring of permafrost

The British Geological Survey, in partnership with the Universities of Sussex and Bonn, is investigating and seeking to prove a new technology concept for the non-invasive volumetric imaging and routine temporal monitoring of the thermal state of permafrost (Figure 1), a key indicator of global climate change. Capacitive Resistivity Imaging (CRI), a technique based upon a low-frequency, capacitively-coupled measurement approach (Kuras et al., 2006) is applied in order to emulate Electrical Resistivity Tomography (ERT) methodology, but without the need for galvanic contact on frozen soils or rocks. Recent work has shown that temperature-calibrated ERT using galvanic sensors (Figure 2) is capable of imaging recession and re-advance of rock permafrost in response to the ambient temperature regime. However, the use of galvanic sensors can lead to significant practical limitations on field measurements due to high levels of and large variations in contact resistances between sensors and the host material as it freezes and thaws Figure 3). The capacitive technology developed here overcomes this problem and provides a more robust means of making high-quality resistance measurements with permanently installed sensors over time. Reducing the uncertainty associated with uncontrolled noise from galvanic sensors increases the value of time-lapse ERT datasets in the context of monitoring permafrost

Complementarity of Galactic radio and collider data in constraining WIMP dark matter models

In this work we confront dark matter models to constraints that may be derived from radio synchrotron radiation from the Galaxy, taking into account the astrophysical uncertainties and we compare these to bounds set by accelerator and complementary indirect dark matter searches. Specifically we apply our analysis to three popular particle physics models. First, a generic effective operator approach, in which case we set bounds on the corresponding mass scale, and then, two specific UV completions, the Z' and Higgs portals. We show that for many candidates, the radio synchrotron limits are competitive with the other searches, and could even give the strongest constraints (as of today) with some reasonable assumptions regarding the astrophysical uncertainties.Comment: 22 pages, 12 figure

Silencing of Vlaro2 for chorismate synthase revealed that the phytopathogen Verticillium longisporum induces the cross-pathway control in the xylem

The first leaky auxotrophic mutant for aromatic amino acids of the near-diploid fungal plant pathogen Verticillium longisporum (VL) has been generated. VL enters its host Brassica napus through the roots and colonizes the xylem vessels. The xylem contains little nutrients including low concentrations of amino acids. We isolated the gene Vlaro2 encoding chorismate synthase by complementation of the corresponding yeast mutant strain. Chorismate synthase produces the first branch point intermediate of aromatic amino acid biosynthesis. A novel RNA-mediated gene silencing method reduced gene expression of both isogenes by 80% and resulted in a bradytrophic mutant, which is a leaky auxotroph due to impaired expression of chorismate synthase. In contrast to the wild type, silencing resulted in increased expression of the cross-pathway regulatory gene VlcpcA (similar to cpcA/GCN4) during saprotrophic life. The mutant fungus is still able to infect the host plant B. napus and the model Arabidopsis thaliana with reduced efficiency. VlcpcA expression is increased in planta in the mutant and the wild-type fungus. We assume that xylem colonization requires induction of the cross-pathway control, presumably because the fungus has to overcome imbalanced amino acid supply in the xylem

The use of capacitive resistivity imaging (CRI) for monitoring laboratory experiments simulating permafrost growth, persistence and thaw in bedrock

Understanding the impact on bedrock properties of permafrost degradation as a result of climate change (Figure 1) is of major interest in a number of areas, including the assessment of rising instability of high-altitude mountain rock walls. The remote sensing of rock walls with the primary aim of monitoring the spatial and temporal behaviour of rock temperature (and thus permafrost distribution) is an emerging field of research for geohazard mitigation where geophysical tomography has the potential to make a significant and lasting contribution. Recent work has shown that temperature-calibrated Electrical Resistivity Tomography (ERT) using galvanic sensors is capable of imaging recession and re-advance of rock permafrost in response to the ambient temperature regime, yet the use of galvanic sensors can impose practical limitations on field measurements (Figure 2). In this study, we evaluate the use of Capacitive Resistivity Imaging (CRI), a technique based upon low-frequency, capacitively-coupled measurements across permanently installed multi-sensor arrays (Kuras et al., 2006), in order to emulate well- established ERT methodology, but without the need for galvanic contact on frozen soils or rocks. The latter is associated with high levels of and large variations in contact resistances between sensors and the host material as it freezes and thaws (Figure 3)

Transvestism and cross dressing Towards an understanding

Includes bibliographical referencesAvailable from British Library Document Supply Centre- DSC:02/42497 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo