Layer potentials beyond singular integral operators

We prove that the double layer potential operator and the gradient of the single layer potential operator are L2 bounded for general second order divergence form systems. As compared to earlier results, our proof shows that the bounds for the layer potentials are independent of well posedness for the Dirichlet problem and of De Giorgi-Nash local estimates. The layer potential operators are shown to depend holomorphically on the coefficient matrix A ∈ L∞, showing uniqueness of the extension of the operators beyond singular integrals. More precisely, we use functional calculus of differential operators with non-smooth cofficients to represent the layer potential operators as bounded Hilbert space operators. In the presence of Moser local bounds, in particular for real scalar equations and systems that are small perturbations of real scalar equations, these operators are shown to be the usual singular integrals. Our proof gives a new construction of fundamental solutions to divergence form systems, valid also in dimension 2

GeMSE: A new Low-Background Facility for Meteorite and Material Screening

We are currently setting up a facility for low-background gamma-ray spectrometry based on a HPGe detector. It is dedicated to material screening for the XENON and DARWIN dark matter projects as well as to the characterization of meteorites. The detector will be installed in a medium depth ($\sim$620 m.w.e.) underground laboratory in Switzerland with several layers of shielding and an active muon-veto. The GeMSE facility will be operational by fall 2015 with an expected background rate of $\sim$250 counts/day (100-2700 keV).Comment: The following article appeared in AIP Conf. Proc. 1672, 120004 (2015) and may be found at http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.4928010. The muon spectrum in Figure 4 (left) was corrected due to a bug in the code. After correction the muon flux is reduced by a factor of about

Forcing mechanisms behind variations in TOC concentration of lake waters Forcing mechanisms behind variations in total organic carbon (TOC) concentration of lake waters during the past eight centuries – palaeolimnological evidence from southern Sweden Forcing mechanisms behind variations in TOC concentration of lake waters

International audienceDecadal-scale variations in total organic carbon (TOC) concentration in lake water since AD 1200 in two small lakes in southern Sweden were reconstructed based on visible-near infrared spectroscopy (VNIRS) of their recent sediment successions. In order to assess the impacts of local land-use changes and regional variations in 5 sulphur deposition and climate on the inferred changes in TOC concentration, the same sediment records were subjected to multi-proxy palaeolimnological analyses. Changes in lake-water pH were inferred from diatom analysis, whereas pollen-based land-use reconstructions (Landscape Reconstruction Algorithm) together with geo-chemical records provided information on catchment-scale environmental changes, 10 and comparisons were made with available records of climate and population density. Our long-term reconstructions reveal that TOC concentrations were generally high prior to AD 1900, with second-order variations coupled mainly to changes in agricultural land-use intensity. The last century showed significant changes, and unusually low TOC concentrations were recorded in 1930–1990, followed by a recent increase. Vari-15 ations in sulphur emissions, with an increase in the early 1900s to a peak around AD 1980 and a subsequent decrease, were most likely the main driver of these dynamics, although processes related to the introduction of modern forestry and recent increases in precipitation and temperature may have contributed. The increase in lake-water TOC concentration from around AD 1980 may therefore reflect a recovery process. Given 20 that the effects of sulphate deposition now subside, other forcing mechanisms related to land management and climate change will possibly become the main drivers of TOC concentration changes in boreal lake waters in the future

Biomarkers of neuronal damage in saturation diving-a controlled observational study

PURPOSE: A prospective and controlled observational study was performed to determine if the central nervous system injury markers glial fibrillary acidic protein (GFAp), neurofilament light (NfL) and tau concentrations changed in response to a saturation dive. METHODS: The intervention group consisted of 14 submariners compressed to 401 kPa in a dry hyperbaric chamber. They remained pressurized for 36 h and were then decompressed over 70 h. A control group of 12 individuals was used. Blood samples were obtained from both groups before, during and after hyperbaric exposure, and from the intervention group after a further 25-26 h. RESULTS: There were no statistically significant changes in the concentrations of GFAp, NfL and tau in the intervention group. During hyperbaric exposure, GFAp decreased in the control group (mean/median - 15.1/ - 8.9 pg·mL-1, p < 0.01) and there was a significant difference in absolute change of GFAp and NfL between the groups (17.7 pg·mL-1, p = 0.02 and 2.34 pg·mL-1, p = 0.02, respectively). Albumin decreased in the control group (mean/median - 2.74 g/L/ - 0.95 g/L, p = 0.02), but there was no statistically significant difference in albumin levels between the groups. In the intervention group, haematocrit and mean haemoglobin values were slightly increased after hyperbaric exposure (mean/median 2.3%/1.5%, p = 0.02 and 4.9 g/L, p = 0.06, respectively). CONCLUSION: Hyperbaric exposure to 401 kPa for 36 h was not associated with significant increases in GFAp, NfL or tau concentrations. Albumin levels, changes in hydration or diurnal variation were unlikely to have confounded the results. Saturation exposure to 401 kPa seems to be a procedure not harmful to the central nervous system. TRIAL REGISTRATION: ClinicalTrials.gov NCT03192930