Simultaneous inversion of source spectra, attenuation parameters and site responses. Application to the data of the French Accelerometric Network.

International audienceDisplacement spectra of earthquakes recorded by the French accelerometric network at regional scale are modeled as the product of source, propagation (including geometric and anelastic attenuation), and site effects. We use an iterative Gauss–Newton inversion to solve the nonlinear problem and retrieve these different terms. This method is easy to implement because the partial derivatives of the amplitude spectrum with respect to the different parameters have simple analytic forms. After convergence, we linearize the problem around the solution to compute the correlation matrix, which allows us to identify the parameters which are poorly resolved. We analyze data from two tectonically active regions: the Alps and the Pyrenees. Eighty-three earthquakes with local magnitudes between 3.0 and 5.3 are analyzed, with epicentral distances in the range 15–200 km. S-wave displacement spectra are computed using a fast Fourier transform and integration in the 0.5–15-Hz frequency domain. We assume a Brune-type source, with a geometric attenuation of the form R-{gamma}, {gamma} being constant, and a frequency-dependent quality factor of the form Q=Q0xf{alpha}. The results reveal that the attenuation parameters are correlated to each other and to the seismic moments. The two regions have different attenuation patterns. The geometrical spreading factor is equal to 1 for the Alps and 1.2 for the Pyrenees. The anelastic attenuation exhibits low Q0 values (322 and 376 for the Alps and the Pyrenees, respectively) with regional variations for {alpha} (0.21 in the Alps and 0.46 in the Pyrenees). Computed moment magnitudes are generally 0.5 unit smaller than local magnitudes, and the logarithms of the corner frequencies decrease linearly with magnitude according to log10(fc)=1.72-0.32xMw. Stress drops range from 105 to 107 Pa (i.e., 1–100 bars), with a slight dependence to magnitude (large stress drops for large magnitudes). Finally, robust site responses relative to an average rock-site response are derived, allowing us to identify good reference rock sites

UNDERSTANDING THE PHYSICS OF KAPPA (Κ0): INSIGHTS FROM THE EUROSEISTEST NETWORK

Στην παρούσα μελέτη υπολογίζουμε την παράμετρο απόσβεσης στις υψηλές συχνότητες, κ0, για το δίκτυο EUROSEISTEST. Οι εδαφικές συνθήκες στους 14 επιφανειακούς και 6 υπόγειους επιταχυνσιογράφους κυμαίνονται από μαλακές αποθέσεις έως σκληρό βράχο. Πρώτα διαχωρίζουμε την τοπική από την περιφερειακή απόσβεση και υπολογίζουμε το κ0. Έπειτα, χρησιμοποιούμε την υπάρχουσα γνώση του εδαφικού προφίλ και των δυναμικών εδαφικών ιδιοτήτων για να συσχετίσουμε το κ0 με διάφορες γεωτεχνικές παραμέτρους (Vs30, συχνότητα συντονισμού, βάθος έως το βραχώδες υπόβαθρο). Τέλος, χρησιμοποιούμε τα αποτελέσματά μας για να βελτιώσουμε τη φυσική κατανόηση του κ0. Προτείνουμε ένα μοντέλο που περιλαμβάνει δύο καινοτόμες ιδέες. Αφ’ ενός, παρατηρούμε πως οι τιμές του κ0 σταθεροποιούνται για υψηλές τιμές Vs, κάτι που πιθανώς σημαίνει πως οι τιμές κ0 συγκλίνουν ανά περιοχή για σκληρό βράχο. Σε αυτήν την περίπτωση, προτείνουμε τη χρήση δεδομένων από όργανα εντός γεωτρήσεων για τον υπολογισμό τους. Αφ’ ετέρου, παρατηρούμε πως η εδαφική απόσβεση δεν επαρκεί για να περιγράψει τη συνολική μετρηθείσα απόσβεση. Προτείνουμε την ύπαρξη μιας επιπλέον πηγής απόσβεσης πέραν της εδαφικής: την απόσβεση διασποράς που οφείλεται στις μικρής κλίμακας ετερογένειες του εδαφικού προφίλ. Σε αυτήν την περίπτωση, οι γεωτεχνικές μετρήσεις της απόσβεσης των υλικών ενδέχεται να μην επαρκούν για την εκτίμηση της συνολικής τοπικής απόσβεσης. Ξεκινώντας όμως από μια εκτίμηση της απόσβεσης της περιοχής (από γεώτρηση), και προσθέτοντας την απόσβεση του υλικού, μπορεί κανείς να προσδιορίσει μία ελάχιστη τιμή για το κ0.this study we estimate the spectral decay factor κ0 for the EUROSEISTEST array. Site conditions range from soft sediments to hard rock over 14 surface and 6 downhole accelerographs. First, we separate local and regional high frequency attenuation and measure κ0. Second, we use the existing knowledge of the geological profile and material properties to correlate κ0 with different site characterisation parameters (Vs30, resonant frequency, depth-to-bedrock). Third, we use our results to improve our physical understanding of κ0. We propose a conceptual model comprising two new notions. On the one hand, we observe that κ0 stabilises for high Vs values; this may indicate the existence of regional values for hard rock κ0. If so, we propose that borehole measurements may be useful in determining them. On the other hand, we find that material damping may not suffice to account for the total measured attenuation. We propose that, apart from damping, additional site attenuation may be caused by scattering from small-scale profile variability. If this is so, then geotechnical damping measurements may not suffice to infer overall crustal attenuation under a site; but starting with a regional (borehole) value and adding damping, we might define a lower bound for site-specific κ0

High-frequency directivity effects: evidence from analysis of the Les Saintes records

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Modelling the contribution of short-range atmospheric and hydrological transfers to nitrogen fluxes, budgets and indirect emissions in rural landscapes

Spatial interactions within a landscape may lead to large inputs of reactive nitrogen (N<sub>r</sub>) transferred from cultivated areas and farms to oligotrophic ecosystems and induce environmental threats such as acidification, nitric pollution or eutrophication of protected areas. The paper presents a new methodology to estimate N<sub>r</sub> fluxes at the landscape scale by taking into account spatial interactions between landscape elements. This methodology includes estimates of indirect N<sub>r</sub> emissions due to short-range atmospheric and hydrological transfers. We used the NitroScape model which integrates processes of N<sub>r</sub> transformation and short-range transfer in a dynamic and spatially distributed way to simulate N<sub>r</sub> fluxes and budgets at the landscape scale. Four configurations of NitroScape were implemented by taking into account or not the atmospheric, hydrological or both pathways of N<sub>r</sub> transfer. We simulated N<sub>r</sub> fluxes, especially direct and indirect N<sub>r</sub> emissions, within a test landscape including pig farms, croplands and unmanaged ecosystems. Simulation results showed the ability of NitroScape to simulate patterns of N<sub>r</sub> emissions and recapture for each landscape element and the whole landscape. NitroScape made it possible to quantify the contribution of both atmospheric and hydrological transfers to N<sub>r</sub> fluxes, budgets and indirect N<sub>r</sub> emissions. For instance, indirect N<sub>2</sub>O emissions were estimated at around 21% of the total N<sub>2</sub>O emissions. They varied within the landscape according to land use, meteorological and soil conditions as well as topography. This first attempt proved that the NitroScape model is a useful tool to estimate the effect of spatial interactions on N<sub>r</sub> fluxes and budgets as well as indirect N<sub>r</sub> emissions within landscapes. Our approach needs to be further tested by applying NitroScape to several spatial arrangements of agro-ecosystems within the landscape and to real and larger landscapes

Apatites in Gale Crater

ChemCam is an active remote sensing instrument suite that has operated successfully on MSL since landing Aug. 6th, 2012. It uses laser pulses to remove dust and to analyze rocks up to 7 m away. Laser-induced breakdown spectroscopy (LIBS) obtains emission spectra of materials ablated from the samples in electronically excited states. The intensities of the emission lines scale with the abundances of the related element. ChemCam is sensitive to most major rock-forming elements as well as to a set of minor and trace elements such as F, Cl, Li, P, Sr, Ba, and Rb. The measured chemical composition can then be used to infer the mineralogical composition of the ablated material. Here, we report a summary of inferred apatite detections along the MSL traverse at Gale Crater. We present the geologic settings of these findings and derive some interpretations about the formation conditions of apatite in time and space

Meeting well-below 2°C target would increase energy sector jobs globally

To limit global warming to well-below 2°C (WB2C), fossil fuels must be replaced by low-carbon energy sources. Support for this transition is often dampened by the impact on fossil fuel jobs. Previous work shows that pro-climate polices could increase employment by 20 million net energy jobs, but these studies rely on Organisation for Economic Co-operation and Development (OECD) jobs data, assumptions about jobs in non-OECD countries, and a single baseline assumption. Here we combine a global dataset of job intensities across 11 energy technologies and five job categories in 50 countries with an integrated assessment model under three shared socioeconomic pathways. We estimate direct energy jobs under a WB2C scenario and current policy scenarios. We find that, by 2050, energy sector jobs would grow from today's 18 million to 26 million under a WB2C scenario compared with 21 million under the current policy scenario. Fossil fuel extraction jobs would rapidly decline, but losses will be compensated by gains in solar and wind jobs, particularly in the manufacturing sector (totaling 7.7 million in 2050)

A new physiological model for studying the effect of chest compression and ventilation during cardiopulmonary resuscitation: The Thiel cadaver

BACKGROUND: Studying ventilation and intrathoracic pressure (ITP) induced by chest compressions (CC) during Cardio Pulmonary Resuscitation is challenging and important aspects such as airway closure have been mostly ignored. We hypothesized that Thiel Embalmed Cadavers could constitute an appropriate model. METHODS: We assessed respiratory mechanics and ITP during CC in 11 cadavers, and we compared it to measurements obtained in 9 out-of-hospital cardiac arrest patients and to predicted values from a bench model. An oesophageal catheter was inserted to assess chest wall compliance, and ITP variation (ΔITP). Airway pressure variation (ΔPaw) at airway opening and ΔITP generated by CC were measured at decremental positive end expiratory pressure (PEEP) to test its impact on flow and ΔPaw. The patient\u27s data were derived from flow and airway pressure captured via the ventilator during resuscitation. RESULTS: Resistance and Compliance of the respiratory system were comparable to those of the out-of-hospital cardiac arrest patients (C 42 ± 12 vs C 37.3 ± 10.9 mL/cmHO and Res 17.5 ± 7.5 vs Res 20.2 ± 5.3 cmHO/L/sec), and remained stable over time. During CC, ΔITP varied from 32 ± 12 cmHO to 69 ± 14 cmHO with manual and automatic CC respectively. Transmission of ΔITP at the airway opening was significantly affected by PEEP, suggesting dynamic small airway closure at low lung volumes. This phenomenon was similarly observed in patients. CONCLUSION: Respiratory mechanics and dynamic pressures during CC of cadavers behave as predicted by a theoretical model and similarly to patients. The Thiel model is a suitable to assess ITP variations induced by ventilation during CC

New damage curves and multimodel analysis suggest lower optimal temperature

Economic analyses of global climate change have been criticized for their poor representation of climate change damages. Here we develop and apply aggregate damage functions in three economic Integrated Assessment Models (IAMs) with different degrees of complexity. The damage functions encompass a wide but still incomplete set of climate change impacts based on physical impact models. We show that with medium estimates for damage functions, global damages are in the range of 10% to 12% of GDP by 2100 in a baseline scenario with 3 °C temperature change, and about 2% in a well-below 2 °C scenario. These damages are much higher than previous estimates in benefit-cost studies, resulting in optimal temperatures below 2 °C with central estimates of damages and discount rates. Moreover, we find a benefit-cost ratio of 1.5 to 3.9, even without considering damages that could not be accounted for, such as biodiversity losses, health and tipping points

Autologous Adipocyte Derived Stem Cells Favour Healing in a Minipig Model of Cutaneous Radiation Syndrome

Cutaneous radiation syndrome (CRS) is the delayed consequence of localized skin exposure to high doses of ionizing radiation. Here we examined for the first time in a large animal model the therapeutic potential of autologous adipose tissue-derived stroma cells (ASCs). For experiments, Göttingen minipigs were locally gamma irradiated using a 60Co source at the dose of 50 Gy and grafted (n = 5) or not (n = 8). ASCs were cultured in MEM-alpha with 10% fetal calf serum and basic fibroblast growth factor (2 ng.mL−1) and post irradiation were intradermally injected on days 25, 46, 67 and finally between days 95 and 115 (50×106 ASCs each time) into the exposed area. All controls exhibited a clinical evolution with final necrosis (day 91). In grafted pigs an ultimate wound healing was observed in four out of five grafted animals (day 130 +/− 28). Immunohistological analysis of cytokeratin expression showed a complete epidermis recovery. Grafted ASCs accumulated at the dermis/subcutis barrier in which they attracted numerous immune cells, and even an increased vasculature in one pig. Globally this study suggests that local injection of ASCs may represent a useful strategy to mitigate CRS