Seismic anisotropy and shear-wave splitting in lower-crustal and upper-mantle rocks from the Ivrea Zone : experimental and calculated data

International audienceTo quantify the relationships between anisotropy. S-wave splitting and tectonics, we determined the seismic properties of lower-crustal and upper-mantle rocks outcropping in the lvrea Zone (Northem Italy). We obtained P-and S-wave seismic velocities by laboratory direct velocity measurements and/or by calculations based on the modal compositions of the rocks, the lattice preferred orientations (LPOs), and the single crystal stiffness coefficients. Measured P-and S-wave velocities (6.0-7 .5 km s-1 and 3.6-4.2 km s-1) are typical of the lower crust. The P-wave anisotropy is in the range 0-l 0%. Shear-wave birefringence is in the range 0.0-0.6 km s-1 , with typical values between 0.0 and 0.2 km s-1 • In many cases, the birefringence is clearly related to fabric elements (foliation, lineation). Mafic rocks such as anorthosite or pyroxene-bearing gabbros exhibit low P-wave anisotropies (< 5%) and low shear-wave birefringences (less than 0.1 km s-1). In contrast, the seismic properties of felsic rocks such as biotite-bearing gneisses and mafic rocks such as amphibolites display high V P anisotropy (10%) and strong birefringence (0.3 km s-1). Biotite and amphibole preferred orientations clearly control seismic anisotropy and particularly shear-wave splitting. In these rocks, maximum splitting is observed in directions parallel to the foliation with the fast split shear wave polarized parallel to the foliation plane. To have an overview of the seismic properties of this lower-crustal section at a broader scale, we calculated from our data the anisotropie seismic properties of several hypothetical samples that are perhaps more representative of the regional anisotropy than each sample individually. For instance, the average lower-crustal sample displays an anisotropy of 5.5% for P waves and a birefringence around 0.14 km s I for S waves propagating parallel to the foliation. We observe little splitting for waves propagating at high angle to the foliation

Illuminating the dark corridor in graphene: polarization dependence of angle-resolved photoemission spectroscopy on graphene

We have used s- and p-polarized synchrotron radiation to image the electronic structure of epitaxial graphene near the K-point by angular resolved photoemission spectroscopy (ARPES). Part of the experimental Fermi surface is suppressed due to the interference of photoelectrons emitted from the two equivalent carbon atoms per unit cell of graphene's honeycomb lattice. Here we show that by rotating the polarization vector, we are able to illuminate this 'dark corridor' indicating that the present theoretical understanding is oversimplified. Our measurements are supported by first-principles photoemission calculations, which reveal that the observed effect persists in the low photon energy regime.Comment: 5 pages, 4 figure

Influence of mechanical ventilation and inhalation of pulmonary vasodilators, upon pulmonary blood flow and pulmonary vascular resistance

Peer Reviewe

Strategies for an adaptive control system to improve power grid resilience with smart buildings

Low-voltage distribution grids face new challenges through the expansion of decentralized, renewable energy generation and the electrification of the heat and mobility sectors. We present a multi-agent system consisting of the energy management systems of smart buildings, a central grid controller, and the local controller of a transformer. It can coordinate the provision of ancillary services for the local grid in a centralized way, coordinated by the central controller, and in a decentralized way, where each building makes independent control decisions based on locally measurable data. The presented system and the different control strategies provide the foundation for a fully adaptive grid control system we plan to implement in the future, which does not only provide resilience against electricity outages but also against communication failures by appropriate switching of strategies. The decentralized strategy, meant to be used during communication failures, could also be used exclusively if communication infrastructure is generally unavailable. The strategies are evaluated in a simulated scenario designed to represent the most extreme load conditions that might occur in low-voltage grids in the future. In the tested scenario, they can substantially reduce voltage range deviations, transformer temperatures, and line congestions

Gastrointestinal Failure score in critically ill patients: a prospective observational study

© 2008 Reintam et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution Licens

Electronic decoupling of an epitaxial graphene monolayer by gold intercalation

The application of graphene in electronic devices requires large scale epitaxial growth. The presence of the substrate, however, usually reduces the charge carrier mobility considerably. We show that it is possible to decouple the partially sp3-hybridized first graphitic layer formed on the Si-terminated face of silicon carbide from the substrate by gold intercalation, leading to a completely sp2-hybridized graphene layer with improved electronic properties.Comment: 7 pages, 4 figures, 1 tabl

Postoperative complications and mortality after major gastrointestinal surgery

Background and objective: The incidence of postoperative complications and death is low in the general population, but a subgroup of high-risk patients can be identified amongst whom adverse postoperative outcomes occur more frequently. The present study was undertaken to describe the incidence of postoperative complications, length of stay, and mortality after major abdominal surgery for gastrointestinal, hepatobiliary and pancreatic malignancies and to identify the risk factors for impaired outcome. Material and methods: Data of patients, operated on for gastro-intestinal malignancies during 2009–2010 were retrieved from the clinical database of Tartu University Hospital. Major outcome data included incidence of postoperative complications, hospital-, 30-day, 90-day and 1-year mortality, and length of ICU and hospital stay. High-risk patients were defined as patients with American Society of Anesthesiologists (ASA) physical status ≥3 and revised cardiac risk index (RCRI) ≥3. Multivariate analysis was used to determine the risk factors for postoperative mortality and morbidity. Results: A total of 507 (259 men and 248 women, mean age 68.3 ± 11.3 years) were operated on for gastrointestinal, hepatobiliary, or pancreatic malignancies during 2009 and 2010 in Tartu University Hospital, Department of Surgical Oncology. 25% of the patients were classified as high risk patients. The lengths of intensive care and hospital stay were 4.4 ± 7 and 14.5 ± 10 days, respectively. The rate of postoperative complications was 33.5% in the total cohort, and 44% in high-risk patients. The most common complication was delirium, which occurred in 12.8% of patients. For patients without high risk (ASA < III; RCRI < 3) in-hospital, 30-, 90-day and 1-year mortality were 2%, 5%, 12.7% and 26.0%. Patients with ASA ≥ III and RCRI ≥ 3 had 2.3% in-hospital mortality, and at 30-, 90 days and 1 year the mortality was 8.5%, 17.8%, and 42.2%, respectively (P = 0.001, P < 0.0001 and P < 0.0001 compared to the lower risk patients). On multivariate analysis, age above 70 years, ASA ≥ III, RCRI ≥ 3, duration of surgery >130 min, and positive fluid balance >1300 mL after the 1st postoperative day, were identified as independent risk factors for the development of complications. Conclusion: The complication rate after major gastro-intestinal surgery is high. ASA physical status and revised cardiac risk index adequately reflect increased risk for postoperative complications and worse short and long-term outcome

Gastrointestinal failure in intensive care: a retrospective clinical study in three different intensive care units in Germany and Estonia

BACKGROUND: While gastrointestinal problems are common in ICU patients with multiple organ failure, gastrointestinal failure has not been given the consideration other organ systems receive. The aim of this study was to evaluate the incidence of gastrointestinal failure (GIF), to identify its risk factors, and to determine its association with ICU mortality. METHODS: A retrospective analysis of adult patients (n = 2588) admitted to three different ICUs (two ICUs at the university hospital Charité-Universitätsmedizin Berlin, Germany and one at Tartu University Clinics, Estonia) during the year 2002 was performed. Data recorded in a computerized database were used in Berlin. In Tartu, the data documented in the patients' charts was retrospectively transferred into a similar database. GIF was defined as documented gastrointestinal problems (food intolerance, gastrointestinal haemorrhage, and/or ileus) in the patient data at any period of their ICU stay. ICU mortality, length of stay, and duration of mechanical ventilation were assessed as outcome parameters. RESULTS: GIF was identified in 252 patients (9.7% of all patients). Only 20% of GIF patients were identifiable at admission. GIF was related to significantly higher mortality (43.7% vs. 5.3% in patients without GIF), as well as prolonged length of ICU stay (10 vs. 2 days) and mechanical ventilation (8 vs. 1 day), p < 0.001, respectively. Patients' profile (emergency surgical or medical), APACHE II and SOFA scores and the use of catecholamines at admission were identified as independent risk factors for the development of GIF. Development of GIF during ICU stay was an independent predictor for death. CONCLUSION: Gastrointestinal failure represents a relevant clinical problem accompanied by an increased mortality, longer ICU stay and mechanical ventilation

Upper limits on the strength of periodic gravitational waves from PSR J1939+2134

The first science run of the LIGO and GEO gravitational wave detectors presented the opportunity to test methods of searching for gravitational waves from known pulsars. Here we present new direct upper limits on the strength of waves from the pulsar PSR J1939+2134 using two independent analysis methods, one in the frequency domain using frequentist statistics and one in the time domain using Bayesian inference. Both methods show that the strain amplitude at Earth from this pulsar is less than a few times $10^{-22}$.Comment: 7 pages, 1 figure, to appear in the Proceedings of the 5th Edoardo Amaldi Conference on Gravitational Waves, Tirrenia, Pisa, Italy, 6-11 July 200