Counterion-Mediated Weak and Strong Coupling Electrostatic Interaction between Like-Charged Cylindrical Dielectrics

We examine the effective counterion-mediated electrostatic interaction between two like-charged dielectric cylinders immersed in a continuous dielectric medium containing neutralizing mobile counterions. We focus on the effects of image charges induced as a result of the dielectric mismatch between the cylindrical cores and the surrounding dielectric medium and investigate the counterion-mediated electrostatic interaction between the cylinders in both limits of weak and strong electrostatic couplings (corresponding, e.g., to systems with monovalent and multivalent counterions, respectively). The results are compared with extensive Monte-Carlo simulations exhibiting good agreement with the limiting weak and strong coupling results in their respective regime of validity.Comment: 19 pages, 10 figure

Overscreening in 1D lattice Coulomb gas model of ionic liquids

Overscreening in the charge distribution of ionic liquids at electrified interfaces is shown to proceed from purely electrostatic and steric interactions in an exactly soluble one dimensional lattice Coulomb gas model. Being not a mean-field effect, our results suggest that even in higher dimensional systems the overscreening could be accounted for by a more accurate treatment of the basic lattice Coulomb gas model, that goes beyond the mean field level of approximation, without any additional interactions.Comment: 4 pages 5 .eps figure

Cubature rules based on bivariate spline quasi-interpolation for weakly singular integrals

In this paper we present a new class of cubature rules with the aim of accurately integrating weakly singular double integrals. In particular we focus on those integrals coming from the discretization of Boundary Integral Equations for 3D Laplace boundary value problems, using a collocation method within the Isogeometric Analysis paradigm. In such setting the regular part of the integrand can be defined as the product of a tensor product B-spline and a general function. The rules are derived by using first the spline quasi-interpolation approach to approximate such function and then the extension of a well known algorithm for spline product to the bivariate setting. In this way efficiency is ensured, since the locality of any spline quasi-interpolation scheme is combined with the capability of an ad--hoc treatment of the B-spline factor. The numerical integration is performed on the whole support of the B-spline factor by exploiting inter-element continuity of the integrand

Investigating the process of ethical approval in citizen science research. The case of public health

Undertaking citizen science research in Public Health involving human subjects poses significant challenges concerning the traditional process of ethical approval. It requires an extension of the ethics of protection of research subjects in order to include the empowerment of citizens as citizen scientists. This paper investigates these challenges and illustrates the ethical framework and the strategies developed within the CitieS-Health project. It also proposes first recommendations generated from the experiences of five citizen science pilot studies in environmental epidemiology within this project

A framework for the first‑person internal sensation of visual perception in mammals and a comparable circuitry for olfactory perception in Drosophila

Perception is a first-person internal sensation induced within the nervous system at the time of arrival of sensory stimuli from objects in the environment. Lack of access to the first-person properties has limited viewing perception as an emergent property and it is currently being studied using third-person observed findings from various levels. One feasible approach to understand its mechanism is to build a hypothesis for the specific conditions and required circuit features of the nodal points where the mechanistic operation of perception take place for one type of sensation in one species and to verify it for the presence of comparable circuit properties for perceiving a different sensation in a different species. The present work explains visual perception in mammalian nervous system from a first-person frame of reference and provides explanations for the homogeneity of perception of visual stimuli above flicker fusion frequency, the perception of objects at locations different from their actual position, the smooth pursuit and saccadic eye movements, the perception of object borders, and perception of pressure phosphenes. Using results from temporal resolution studies and the known details of visual cortical circuitry, explanations are provided for (a) the perception of rapidly changing visual stimuli, (b) how the perception of objects occurs in the correct orientation even though, according to the third-person view, activity from the visual stimulus reaches the cortices in an inverted manner and (c) the functional significance of well-conserved columnar organization of the visual cortex. A comparable circuitry detected in a different nervous system in a remote species-the olfactory circuitry of the fruit fly Drosophila melanogaster-provides an opportunity to explore circuit functions using genetic manipulations, which, along with high-resolution microscopic techniques and lipid membrane interaction studies, will be able to verify the structure-function details of the presented mechanism of perception

Distribution, composition and origin of coalbed gases in excavation fields from the Preloge and Pesje mining areas, Velenje Basin, Slovenia

Coal gas outbursts (especially CO2) present a high risk in mining of lignite in the Velenje Coal Mine, located in the Velenje Basin in northern Slovenia. A programme of monitoring geochemical parameters was set up to help understand the behaviour of the coalbed gas distribution in advance of the working face using mass spectrometric methods to study its molecular and isotopic compositions and origin. Coalbed gas samples from four different excavation fields (G2/C and K.-130/A from the north and south Preloge mining area and K.-5/A and K.-50/C from the Pesje mining area), which were operational between the years 2010 and 2011 were investigated. The major gas components are CO2 and methane. Temporal changes in the chemical and isotopic composition of free seamgaseswere observedwithin boreholes as a function of the advancement of theworking face. The study also revealed that at a distance of around 120 m from the working face, the influence of coal exploitation by the Velenje Longwall Mining Method causes coalbed gas to migrate. At a distance of 70 m the lignite structure is crushed causing desorption of fixed CO2 from the coal. Differences in coalbed gas composition at the longwall panels which underlie the unmined area or under previously mined areas were found. A high CDMI {=[CO2/(CO2+CH4)]100 (%)} indexwith values up to 95.6% was typical for areas of pre-mined excavation fields (South Preloge K.-130/A and Pesje area K.-5/A), while in excavation fieldswith no previous mining activity (North Preloge G2/C and Pesje area K.-50/C) up to 61.9 vol % of CH4 was detected. The concentration measurements and isotopic studies revealed endogenic CO2 (including CO2 originating from dissolution of carbonates) with δ13CCO2 values ranging from −7.0‰ to 5.5‰, microbial methane and CO2 with values ranging from −70.4 to −50‰ and from −11.0 to −7.0‰, respectively. Higher δ13CCH4 values ranging from −50 to −19.8‰ could be attributed to so-called secondary processes influencing the δ13CCH4 value, such as migration due to lignite excavation (escape of isotopically lighter methane). In excavation fields (G2/C and K.-50/C) with no-premining activity higher δ13CCH4 values could also be explained by migration of methane fromdeeper strata. The δ13CCH4 value also depended on the depth of the excavation field; at shallower levels of the excavation field (K.-5/A) a lower δ13CCH4 value was traced indicating microbial gas, while at deeper levels higher δ13CCH4 values were found.Slovenian Research Agency (L2-4066 and L1-5451)Published363-3775A. Energia e georisorseJCR Journalrestricte

Distribution, composition and origin of coalbed gases in excavation fields from the Preloge and Pesje mining areas, Velenje Basin, Slovenia

Coal gas outbursts (especially CO2) present a high risk in mining of lignite in the Velenje Coal Mine, located in the Velenje Basin in northern Slovenia. A programme of monitoring geochemical parameters was set up to help understand the behaviour of the coalbed gas distribution in advance of the working face using mass spectrometric methods to study its molecular and isotopic compositions and origin. Coalbed gas samples from four different excavation fields (G2/C and K.-130/A from the north and south Preloge mining area and K.-5/A and K.-50/C from the Pesje mining area), which were operational between the years 2010 and 2011 were investigated. The major gas components are CO2 and methane. Temporal changes in the chemical and isotopic composition of free seamgaseswere observedwithin boreholes as a function of the advancement of theworking face. The study also revealed that at a distance of around 120 m from the working face, the influence of coal exploitation by the Velenje Longwall Mining Method causes coalbed gas to migrate. At a distance of 70 m the lignite structure is crushed causing desorption of fixed CO2 from the coal. Differences in coalbed gas composition at the longwall panels which underlie the unmined area or under previously mined areas were found. A high CDMI {=[CO2/(CO2+CH4)]100 (%)} indexwith values up to 95.6% was typical for areas of pre-mined excavation fields (South Preloge K.-130/A and Pesje area K.-5/A), while in excavation fieldswith no previous mining activity (North Preloge G2/C and Pesje area K.-50/C) up to 61.9 vol % of CH4 was detected. The concentration measurements and isotopic studies revealed endogenic CO2 (including CO2 originating from dissolution of carbonates) with δ13CCO2 values ranging from −7.0‰ to 5.5‰, microbial methane and CO2 with values ranging from −70.4 to −50‰ and from −11.0 to −7.0‰, respectively. Higher δ13CCH4 values ranging from −50 to −19.8‰ could be attributed to so-called secondary processes influencing the δ13CCH4 value, such as migration due to lignite excavation (escape of isotopically lighter methane). In excavation fields (G2/C and K.-50/C) with no-premining activity higher δ13CCH4 values could also be explained by migration of methane fromdeeper strata. The δ13CCH4 value also depended on the depth of the excavation field; at shallower levels of the excavation field (K.-5/A) a lower δ13CCH4 value was traced indicating microbial gas, while at deeper levels higher δ13CCH4 values were found

A geochemical and stable isotope investigation of groundwater/surface-water interactions in the Velenje Basin, Slovenia

The geochemical and isotopic composition of surface waters and groundwater in the Velenje Basin, Slovenia, was investigated seasonally to determine the relationship between major aquifers and surface waters, water–rock reactions, relative ages of groundwater, and biogeochemical processes. Groundwater in the Triassic aquifer is dominated by HCO3 –, Ca2+, Mg2+ and δ13CDIC indicating degradation of soil organic matter and dissolution of carbonate minerals, similar to surface waters. In addition, groundwater in the Triassic aquifer has δ18O and δD values that plot near surface waters on the local and global meteoric water lines, and detectable tritium, likely reflecting recent (<50 years) recharge. In contrast, groundwater in the Pliocene aquifers is enriched in Mg2+, Na+ , Ca2+, K+, and Si, and has high alkalinity and δ13CDIC values, with low SO4 2– and NO3 – concentrations. These waters have likely been influenced by sulfate reduction and microbial methanogenesis associated with coal seams and dissolution of feldspars and Mg-rich clay minerals. Pliocene aquifer waters are also depleted in 18O and 2H, and have 3H concentrations near the detection limit, suggesting these waters are older, had a different recharge source, and have not mixed extensively with groundwater in the Triassic aquifer