The critical Ising model on a torus with a defect line

The critical Ising model in two dimensions with a defect line is analyzed to deliver the first exact solution with twisted boundary conditions. We derive exact expressions for the eigenvalues of the transfer matrix and obtain analytically the partition function and the asymptotic expansions of the free energy and inverse correlation lengths for an infinitely long cylinder of circumference $L_x$. We find that finite-size corrections to scaling are of the form $a_k/L^{2k-1}_x$ for the free energy $f$ and $b_k(p)/L_x^{2k-1}$ and $c_k(p)/L_x^{2k-1}$ for inverse correlation lengths $\xi^{-1}_p$ and $\xi^{-1}_{L-p}$, respectively, with integer values of $k$. By exact evaluation we find that the amplitude ratios $b_k(p)/a_k$ and $c_k(p)/a_k$ are universal and verify this universal behavior using a perturbative conformal approach.Comment: 5 pages, 5 figures, added Acknowledgment

Deposition, Accumulation, and Alteration of Cl(-), NO3(-), ClO4(-) and ClO3(-) Salts in a Hyper-Arid Polar Environment: Mass Balance and Isotopic Constraints

The salt fraction in permafrost soils/sediments of the McMurdo Dry Valleys (MDV) of Antarctica can be used as a proxy for cold desert geochemical processes and paleoclimate reconstruction. Previous analyses of the salt fraction in MDV permafrost soils have largely been conducted in coastal regions where permafrost soils are variably affected by aqueous processes and mixed inputs from marine and stratospheric sources. We expand upon this work by evaluating permafrost soil/sediments in University Valley, located in the ultraxerous zone where both liquid water transport and marine influences are minimal. We determined the abundances of Cl(-), NO3(-, ClO4(-)and ClO3(-)in dry and ice-cemented soil/sediments, snow and glacier ice, and also characterized Cl(-) and NO3(-) isotopically. The data are not consistent with salt deposition in a sublimation till, nor with nuclear weapon testing fall-out, and instead point to a dominantly stratospheric source and to varying degrees of post depositional transformation depending on the substrate, from minimal alteration in bare soils to significant alteration (photodegradation and/or volatilization) in snow and glacier ice. Ionic abundances in the dry permafrost layer indicate limited vertical transport under the current climate conditions, likely due to percolation of snowmelt. Subtle changes in ClO4(-)/NO3(-) ratios and NO3(-) isotopic composition with depth and location may reflect both transport related fractionation and depositional history. Low molar ratios of ClO3(-)/ClO4(-) in surface soils compared to deposition and other arid systems suggest significant post depositional loss of ClO3(-), possibly due to reduction by iron minerals, which may have important implications for oxy-chlorine species on Mars. Salt accumulation varies with distance along the valley and apparent accumulation times based on multiple methods range from approximately 10 to 30 kyr near the glacier to 70-200 kyr near the valley mouth. The relatively young age of the salts and relatively low and homogeneous anion concentrations in the ice-cemented sediments point to either a mechanism of recent salt removal, or to relatively modern permafrost soils (less than 1 million years). Together, our results show that near surface salts in University Valley serve as an end-member of stratospheric sources not subject to biological processes or extensive remobilization

Perchlorate in The Great Lakes: Isotopic Composition and Origin

Perchlorate is a persistent and mobile contaminant in the environment with both natural and anthropogenic sources. Stable isotope ratios of oxygen (δ^(18)O, Δ^(17)O) and chlorine (δ^(37)Cl) along with the abundance of the radioactive isotope ^(36)Cl were used to trace perchlorate sources and behavior in the Laurentian Great Lakes. These lakes were selected for study as a likely repository of recent atmospheric perchlorate deposition. Perchlorate concentrations in the Great Lakes range from 0.05 to 0.13 μg per liter. Δ^(37)Cl values of perchlorate from the Great Lakes range from +3.0‰ (Lake Ontario) to +4.0‰ (Lake Superior), whereas δ^(18)O values range from −4.1‰ (Lake Superior) to +4.0‰ (Lake Erie). Great Lakes perchlorate has mass-independent oxygen isotopic variations with positive Δ^(17)O values (+1.6‰ to +2.7‰) divided into two distinct groups: Lake Superior (+2.7‰) and the other four lakes (∼+1.7‰). The stable isotopic results indicate that perchlorate in the Great Lakes is dominantly of natural origin, having isotopic composition resembling that measured for indigenous perchlorate from preindustrial groundwaters of the western USA. The ^(36)Cl/Cl ratio of perchlorate varies widely from 7.4 × 10^(–12) (Lake Ontario) to 6.7 × 10^(–11) (Lake Superior). These ^(36)ClO_4– abundances are consistent with an atmospheric origin of perchlorate in the Great Lakes. The relatively high ^(36)ClO_4– abundances in the larger lakes (Lakes Superior and Michigan) could be explained by the presence of ^(36)Cl-enriched perchlorate deposited during the period of elevated atmospheric ^(36)Cl activity following thermonuclear bomb tests in the Pacific Ocean

A note on RG domain wall between successive A2(p)A_2^{(p)} minimal models

We investigate the RG domain wall between neighboring $A_2^{(p)}$ minimal CFT models and establish the map between UV and IR fields (matrix of mixing coefficients). A particular RG invariant set of six primary and four descendant fields is analyzed in full details. Using the algebraic construction of the RG domain wall we compute the UV/IR mixing matrix. To test our results we show that it diagonalizes the matrix of anomalous dimensions previously known from perturbative analysis. It is important to note that the diagonalizing matrix can not be found from perturbative analysis solely due to degeneracy of anomalous dimensions. The same mixing coefficients are used to explore anomalous W-weights as well.Comment: 25 page

A note on RG domain wall between successive A 2 p A2(p) {A}_2^{(p)} minimal models

Abstract We investigate the RG domain wall between neighboring A 2 p $${A}_2^{(p)}$$ minimal CFT models and establish the map between UV and IR fields (matrix of mixing coefficients). A particular RG invariant set of six primary and four descendant fields is analyzed in full details. Using the algebraic construction of the RG domain wall we compute the UV/IR mixing matrix. To test our results we show that it diagonalizes the matrix of anomalous dimensions previously known from perturbative analysis. It is important to note that the diagonalizing matrix can not be found from perturbative analysis solely due to degeneracy of anomalous dimensions. The same mixing coefficients are used to explore anomalous W-weights as well

Global Geochemical Cycle of Perchlorate

The Great Lakes hydrologic system is one of the world’s most valuable natural resources, and over time its value will only rise with increasing fresh water demand of the fast-growing human population. Millions of people and a wide range of large industries both in the United States and Canada depend on the Great Lakes for their water supply. Despite having some negative effects on the Great Lakes, the industrialization of this region has enormous economical benefits for both countries, thus making it implausible to ban all activities or compounds that could potentially degrade Great Lakes water quality. The key for sustainable future development is to maintain the economic vitality of the Great Lakes region without compromising the ecological balance and water quality in the Great Lakes basin. In order to sustain environmentally sound progress in the Great Lakes region it is essential to have a comprehensive understanding of the behavior and origin of contaminants having potentially adverse effects on the ecosystem. As a contribution to this understanding, we investigated perchlorate origin, transport, and biodegradation and uptake in all five lakes by using perchlorate concentrations, oxygen and chlorine isotope ratios (δ18O, Δ17O, δ37Cl, 36Cl/Cl). In addition, we investigated the isotopic composition of chloride from the Great Lakes (δ37Cl, 36Cl/Cl) to provide a comparison of perchlorate with a relatively well-understood conservative contaminant. Overall, this study has identified the dominant source of Great Lakes perchlorate and evaluated its biogeochemical cycle in a hydrological context. The combination of concentration and isotopic analyses and numerical models quantify the perchlorate inputs from all potential sources and perchlorate outputs through outflow and other processes (e.g. biodegradation and uptake). We also quantified isotopic fractionation effects associated with the perchlorate loss in the Great Lakes basin. The numerical models successfully explain the observed temporal evolution of 36Cl/Cl ratios in perchlorate and chloride from the Great Lakes over the last 70 years. The new insights obtained on the behavior of these conservative solutes may provide a useful reference for studies of the origin and behavior of other contaminants in the Great Lakes system

Evaluation of Malondialdehyde Levels, Oxidative Stress and Host–Bacteria Interactions: Escherichia coli and Salmonella Derby

Either extracts, cell-free suspensions or bacterial suspensions are used to study bacterial lipid peroxidation processes. Along with gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry, and several other strategies, the thiobarbituric acid test is used for the determination of malondialdehyde (MDA) as the basis for the commercial test kits and the colorimetric detection of lipid peroxidation. The aim of the current study was to evaluate lipid peroxidation processes levels in the suspensions, extracts and culture supernatants of Escherichia coli and Salmonella Derby strains. The dependence of the formation of thiobarbituric acid-reactive substances levels in the cell extracts, the suspensions and cell-free supernatants on bacterial species, and their concentration and growth phase were revealed. The effect of bacterial concentrations on MDA formation was also found to be more pronounced in bacterial suspensions than in extracts, probably due to the dynamics of MDA release into the intercellular space. This study highlights the possible importance of MDA determination in both cell-free suspensions and extracts, as well as in bacterial suspensions to elucidate the role of lipid peroxidation processes in bacterial physiology, bacteria–host interactions, as well as in host physiology