Multiple Dual C−Cl Isotope Patterns Associated with Reductive Dechlorination of Tetrachloroethene

Dual isotope slopes are increasingly used to identify transformation pathways of contaminants. We investigated if reductive dechlorination of tetrachloroethene (PCE) by consortia containing bacteria with different reductive dehalogenases (rdhA) genes can lead to variable dual C−Cl isotope slopes and if different slopes also occur in the field. Two bacterial enrichments harboring Sulfurospirillum spp. but different rdhA genes yielded two distinct δ13C to δ37Cl slopes of 2.7 ± 0.3 and 0.7 ± 0.2 despite a high similarity in gene sequences. This suggests that PCE reductive dechlorination could be catalyzed according to at least two distinct reaction mechanisms or that rate-limiting steps might vary. At two field sites, two distinct dual isotope slopes of 0.7 ± 0.3 and 3.5 ± 1.6 were obtained, each of which fits one of the laboratory slopes within the range of uncertainty. This study hence provides additional insight into multiple reaction mechanisms underlying PCE reductive dechlorination. It also demonstrates that caution is necessary if a dual isotope approach is used to differentiate between transformation pathways of chlorinated ethenes

The effect of pH-neutral peritoneal dialysis fluids on adipokine secretion from cultured adipocytes

Background. Adipokines are a group of fat-secreted hormones and cytokines, including leptin and adiponectin, with important functions in humans. Peritoneal dialysis (PD) is associated with markedly raised plasma adipokines, suggesting increased production in this setting. We have shown that low pH down-regulates leptin production. The current study was designed to test if novel pH-neutral PD fluids may regulate leptin and adiponectin secretion in vitro. Methods. We exposed 3T3-L1 adipocytes to a 50 : 50 mixture of dialysate and M199 containing 10% serum for upto 48 h. Dialysates were commercial PD fluids, i.e. conventional acidic, lactate-buffered solutions (PD-acid) and pH-neutral lactate-buffered (PD-Bal) or bicarbonate-buffered solutions (PD-Bic). Leptin and adiponectin concentrations in culture-cell media were measured by ELISA. Results. Compared with PD-acid, PD-Bal and PD-Bic produced a 25 and 43% increase, respectively, in leptin secretion at 48 h (P < 0.05). In contrast, adiponectin secretion was not affected. High glucose PD fluids (4.25%) specifically inhibited leptin secretion vs 1.5% glucose, buffer-matched solutions (P < 0.05). However, differences in leptin secretion due to pH and type of buffer remained significant. In further experiments, the pH of test media were extensively varied without the presence of dialysates. Leptin secretion was shown to increase in a parallel to pH, whereas large changes in pH did not affect adiponectin secretion. Conclusion. The pH-neutral PD solutions specifically induce leptin, but not adiponectin secretion from 3T3-L1 adipocytes. PD-Bic produced a greater leptin stimulation than PD-Bal, but this difference was attributable to pH per se, rather than the type of buffe

Evaluating the Impacts of Sea Level Rise and Storm Surges on Seychelles' Critical Infrastructure: Summary for Policy Makers

The Republic of Seychelles, like other island nations, is at risk from anthropogenic climate change. Adapting to future climate change requires making difficult decisions under conditions of uncertainty. While the uncertainty cannot be fully resolved, informed adaptation decisions can be made by broadly appraising the various dimensions of risk—climate hazards, exposure, and vulnerability—posed by sea level rise and storm surge to Seychelles’ critical infrastructure. Global climate models, local climate feature projections, and local climate trends were synthesized to create five climate scenarios to guide Seychelles’ adaptation decision-making. Vulnerability maps were created by combining local climate and socioeconomic data into a Geographic Information Systems (GIS) format. This report concludes with a list of recommendations aimed at better protecting Seychelles’ critical infrastructure from sea level rise and storm surge and fostering climate-resilient development. In addition to this report, the project developed online risk maps and a Climate Scenario Planning Toolkit, all of which were designed to meet the needs of local stakeholders. This work is part of a larger effort by the United Nations Framework Convention on Climate Change (UNFCCC), known as the Lima Adaptation Knowledge Initiative (LAKI), which aims to close knowledge gaps regarding climate adaptation. In this capacity, it will serve not only to guide the Seychelles Government’s approach to climate change adaptation but may also aid other island nations facing similar climate risks.Master of ScienceSchool for Environment and SustainabilityUniversity of Michiganhttps://deepblue.lib.umich.edu/bitstream/2027.42/155352/1/Seychelles Summary for Policymakers.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155352/3/Summary for Policymakers_368.pdfDescription of Seychelles Summary for Policymakers.pdf : Summary for Policy Maker

Uncertainty principles for magnetic structures on certain coadjoint orbits

By building on our earlier work, we establish uncertainty principles in terms of Heisenberg inequalities and of the ambiguity functions associated with magnetic structures on certain coadjoint orbits of infinite-dimensional Lie groups. These infinite-dimensional Lie groups are semidirect products of nilpotent Lie groups and invariant function spaces thereon. The recently developed magnetic Weyl calculus is recovered in the special case of function spaces on abelian Lie groups.Comment: 19 page

Toxicity in Multilingual Machine Translation at Scale

Machine Translation systems can produce different types of errors, some of which are characterized as critical or catastrophic due to the specific negative impact that they can have on users. In this paper we focus on one type of critical error: added toxicity. We evaluate and analyze added toxicity when translating a large evaluation dataset (HOLISTICBIAS, over 472k sentences, covering 13 demographic axes) from English into 164 languages. An automatic toxicity evaluation shows that added toxicity across languages varies from 0% to 5%. The output languages with the most added toxicity tend to be low-resource ones, and the demographic axes with the most added toxicity include sexual orientation, gender and sex, and ability. We also perform human evaluation on a subset of 8 translation directions, confirming the prevalence of true added toxicity. We use a measurement of the amount of source contribution to the translation, where a low source contribution implies hallucination, to interpret what causes toxicity. Making use of the input attributions allows us to explain toxicity, because the source contributions significantly correlate with toxicity for 84% of languages studied. Given our findings, our recommendations to reduce added toxicity are to curate training data to avoid mistranslations, mitigate hallucination and check unstable translations