Modeling extreme values of processes observed at irregular time steps: Application to significant wave height

This work is motivated by the analysis of the extremal behavior of buoy and satellite data describing wave conditions in the North Atlantic Ocean. The available data sets consist of time series of significant wave height (Hs) with irregular time sampling. In such a situation, the usual statistical methods for analyzing extreme values cannot be used directly. The method proposed in this paper is an extension of the peaks over threshold (POT) method, where the distribution of a process above a high threshold is approximated by a max-stable process whose parameters are estimated by maximizing a composite likelihood function. The efficiency of the proposed method is assessed on an extensive set of simulated data. It is shown, in particular, that the method is able to describe the extremal behavior of several common time series models with regular or irregular time sampling. The method is then used to analyze Hs data in the North Atlantic Ocean. The results indicate that it is possible to derive realistic estimates of the extremal properties of Hs from satellite data, despite its complex space--time sampling.Comment: Published in at http://dx.doi.org/10.1214/13-AOAS711 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Larra: From Polyphony to Textual Rebellion

In the first chapter of his seminal Problems of Dostoevsky’s Poetics, Mikhail Bakhtin argues that the multitude of memorable characters in the Russian novelist’s works have led to a certain fragmentation of the author’s persona, giving the impression that “one is dealing not with a single author-artist who wrote novels and stories, but with a number of philosophical statements by several author-thinkers.” Similarly, he remarks that scholarly criticism had largely fallen prey to a comparable reading of Dostoevsky’s works, privileging individual characters’ voices, in the process splintering the author-figure by merging it with each individual character, as if it were “not an object of authorial discourse, but rather a fully valid, autonomous carrier of his own individual word” (5)

Modeling processes asymmetries with Laplace Moving Average.

Many records in environmental science exhibit asymmetries: for example in shallow water and with variable bathymetry, the sea wave time series shows front-back asymmetries and different shapes for crests and troughs. In such situation, numerical models are available but are highly CPU-time consuming. A stochastic process aimed at modeling such asymmetries has already been proposed, the Laplace Moving Average process. The objective of this study is to propose a new estimator of the defining function in a non-parametric approach. Results based on a comprehensive numerical study will be shown in order to evaluate the performances of the proposed method

A Survey on the Use of Spirometry in Small Animal Anaesthesia and Critical Care

The objective was to document the use of spirometry and ventilation settings in small animal anaesthesia and intensive care through a descriptive, open, online, anonymous survey. The survey was advertised on social media and via email. Participation was voluntary. The google forms platform was used. It consisted of eight sections in English: demographic information, use of spirometry in spontaneously ventilating/mechanically ventilated dogs, need for spirometry, equipment available and calibration status, ventilation modes, spirometry displays, compliance (CRS) and resistance (RRS) of the respiratory system. Simple descriptive analyses were applied. There were 128 respondents. Respondents used spirometry more in ventilated dogs than during spontaneous breathing. Over 3/4 of the respondents considered spirometry essential in “selected” (43%) or “most” cases (33%). Multiple devices and technologies were used. The majority of the respondents were not directly involved in or informed about the calibration of their equipment. Of all displays, pressure-volume loops were the most common. Values of CRS and RRS were specifically monitored in more than 50% of cases by 44% of the respondents only. A variety of ventilation modes was used. Intensivists tend to use smaller VT than anaesthetists. More information on reference intervals of CRS and RRS and technical background on spirometers is required

A survey on the use of spirometry in small animal anaesthesia and critical care

The objective was to document the use of spirometry and ventilation settings in small animal anaesthesia and intensive care through a descriptive, open, online, anonymous survey. The survey was advertised on social media and via email. Participation was voluntary. The google forms platform was used. It consisted of eight sections in English: demographic information, use of spirometry in spontaneously ventilating/mechanically ventilated dogs, need for spirometry, equipment available and calibration status, ventilation modes, spirometry displays, compliance (CRS) and resistance (RRS) of the respiratory system. Simple descriptive analyses were applied. There were 128 respondents. Respondents used spirometry more in ventilated dogs than during spontaneous breathing. Over 3/4 of the respondents considered spirometry essential in “selected” (43%) or “most” cases (33%). Multiple devices and technologies were used. The majority of the respondents were not directly involved in or informed about the calibration of their equipment. Of all displays, pressure-volume loops were the most common. Values of CRS and RRS were specifically monitored in more than 50% of cases by 44% of the respondents only. A variety of ventilation modes was used. Intensivists tend to use smaller VT than anaesthetists. More information on reference intervals of CRS and RRS and technical background on spirometers is require

Design of steel surface and wetting properties by laser patterning

Nowadays, the actual industries require massive cost savings. Thus, it makes sense to improve basic materials. Various properties may be changed to design consumption-friendly materials and to enhance effciency (e.g. improve heating and abrasive resistance), friction, adhesion and lubrication of materials. Hence, patterning techniques are useful tools to tailor the material properties according to a simple guideline: "have the right property at the right place". Numerous techniques are based on surface modifications and involve light sources. Since the achievement of modern laser systems, fast to ultrafast laser are used in labs and industrial groups. They have legion advantages in comparison to embossing techniques such as material patterning without mechanical contact and allow a sub micro-precision. During this thesis, two techniques were used in order to develop and enhance the surface properties of the 100Cr6 steel: the femtosecond laser ablation and laser interference metallurgy. First, the bearing properties were enhanced by a smart and advanced design of the surface. Secondly, the hydro- and oleophilic properties of irradiated samples were studied and compared to non-irradiated. Finally, a combination of both techniques was performed in order to unite the wetting advantages of both patterning methods. Various patterns were elaborated in order to determine an optimal structure design and the chemical and topographical properties were consistently evaluated and comparedHeutzutage müssen sowohl Forschung als auch moderne Industrie so kostengünstig wie möglich arbeiten. Deshalb ist es sinnvoll, Standard-Materialien bzw. deren Eigenschaften zu verbessern: Dies gelingt durch geringeren Brennstoff-Verbrauch, Erhöhen der Materialeffzienz (z.B. besserer Erwärmungs- und Verschleiß-Widerstand), Reibung und Adhäsion, Schmierung, usw. Texturierungsmethoden sind imstande, die Materialeigenschaften gemäß eines einfachen Prinzips auszubilden: "die richtigen Eigenschaften an der richtigen Stelle ". Techniken auf Basis von Lichtquellen erlauben solches Design, weshalb kurze und ultra-kurze Laser-Systeme in Entwicklungsabteilungen genutzt werden. Gegenüber Prägungsmethoden ergeben sich zahlreiche Vorteile. Das Verfahren funktioniert ohne mechanischen Kontakt und mit einer submikron-Präzision. Zwei Lasermethoden wurden benutzt, um die 100Cr6 Stahl Eigenschaften zu verbessern: die Femtosekunden Laser Ablation und Laser Interferenz Metallurgie. Zuerst wurde die Tragfähigkeit durch ein sinnvolles Design verbessert. Danach wurden das hydro- und oleophile Verhalten von texturierten Proben untereinander und mit unstrukturierten Proben verglichen. Abschließend wurden die beiden Laser-Prozesse miteinander kombiniert, um so die Vorteile der jeweiligen Methode zu erhalten. Mehrere Muster wurden hergestellt, um ein optimiertes Design zu erzeugen. Die chemischen und topographischen Eigenschaften der Strukturen wurden stets charakterisiert und miteinander verglichen

Design of steel surface and wetting properties by laser patterning

Nowadays, the actual industries require massive cost savings. Thus, it makes sense to improve basic materials. Various properties may be changed to design consumption-friendly materials and to enhance effciency (e.g. improve heating and abrasive resistance), friction, adhesion and lubrication of materials. Hence, patterning techniques are useful tools to tailor the material properties according to a simple guideline: "have the right property at the right place". Numerous techniques are based on surface modifications and involve light sources. Since the achievement of modern laser systems, fast to ultrafast laser are used in labs and industrial groups. They have legion advantages in comparison to embossing techniques such as material patterning without mechanical contact and allow a sub micro-precision. During this thesis, two techniques were used in order to develop and enhance the surface properties of the 100Cr6 steel: the femtosecond laser ablation and laser interference metallurgy. First, the bearing properties were enhanced by a smart and advanced design of the surface. Secondly, the hydro- and oleophilic properties of irradiated samples were studied and compared to non-irradiated. Finally, a combination of both techniques was performed in order to unite the wetting advantages of both patterning methods. Various patterns were elaborated in order to determine an optimal structure design and the chemical and topographical properties were consistently evaluated and comparedHeutzutage müssen sowohl Forschung als auch moderne Industrie so kostengünstig wie möglich arbeiten. Deshalb ist es sinnvoll, Standard-Materialien bzw. deren Eigenschaften zu verbessern: Dies gelingt durch geringeren Brennstoff-Verbrauch, Erhöhen der Materialeffzienz (z.B. besserer Erwärmungs- und Verschleiß-Widerstand), Reibung und Adhäsion, Schmierung, usw. Texturierungsmethoden sind imstande, die Materialeigenschaften gemäß eines einfachen Prinzips auszubilden: "die richtigen Eigenschaften an der richtigen Stelle ". Techniken auf Basis von Lichtquellen erlauben solches Design, weshalb kurze und ultra-kurze Laser-Systeme in Entwicklungsabteilungen genutzt werden. Gegenüber Prägungsmethoden ergeben sich zahlreiche Vorteile. Das Verfahren funktioniert ohne mechanischen Kontakt und mit einer submikron-Präzision. Zwei Lasermethoden wurden benutzt, um die 100Cr6 Stahl Eigenschaften zu verbessern: die Femtosekunden Laser Ablation und Laser Interferenz Metallurgie. Zuerst wurde die Tragfähigkeit durch ein sinnvolles Design verbessert. Danach wurden das hydro- und oleophile Verhalten von texturierten Proben untereinander und mit unstrukturierten Proben verglichen. Abschließend wurden die beiden Laser-Prozesse miteinander kombiniert, um so die Vorteile der jeweiligen Methode zu erhalten. Mehrere Muster wurden hergestellt, um ein optimiertes Design zu erzeugen. Die chemischen und topographischen Eigenschaften der Strukturen wurden stets charakterisiert und miteinander verglichen

Do the Manual or Computer-Controlled Flowmeters Generate Similar Isoflurane Concentrations in Tafonius?

Introduction: Tafonius is an anesthesia machine with computer-controlled monitor and ventilator. We compared the isoflurane fluctuations in the circuit with manual (MF) or computer-driven (CF) flowmeters, investigated the origin of the differences and assessed whether isoflurane concentration time course followed a one-compartment model.Material and Methods: A calibrated TEC-3 isoflurane vaporizer was used. Gas composition and flows were measured using a multiparametric monitor and a digital flowmeter. Measurements included: (1) Effects of various FiO2 with MF/CF on the isoflurane fraction changes in the breathing system during mechanical ventilation of a lung model; wash-in kinetic was fitted to a compartmental model; (2) Gas outflow at the common gas outlet (CGO) with MF/CF at different FiO2; (3) Isoflurane output of the vaporizer at various dial settings with MF/CF set at different flows without and with reduction of the CGO diameter.Results: (1) The 3% targeted isoflurane concentration was not reached; additional time was required to reach specific concentrations with CF (lowest FiO2, longer time). The exponential course fitted a two-compartment model; (2) Set and measured flows were identical with MF. With CF at 0.21 FiO2, flow was intermittently 7.6 L min−1 or zero (mean total: 38% of the set flow); with CF at 1.00 FiO2, flow was 10.6 L min−1 or zero (mean: 4–5.3 L min−1); with 0.21 < FiO2 < 1.00, combined flow was intermittent (maximum output: 15.6 L min−1); (3) With MF, isoflurane output was matching dial setting at 5 L min−1 but was lower at higher flows; with CF generating intermittent flows, isoflurane output was fluctuating. With the 4 mm diameter CGO, isoflurane concentration was close to dial setting with both MF and CF. With a 14 G CGO, isoflurane concentration was lower than dial setting with MF, higher with CF.Conclusions and Clinical Relevance: Using MF or CF led to different isoflurane fraction time course in Tafonius. Flows were lower than set with CF; the TEC-3 did not compensate for high/intermittent flows and pressures; the CGO diameter influenced isoflurane output

Global heat flow trends resolved from multiple geological and geophysical proxies

International audienceBecause global coverage of heat flow measurements is still poor in many areas, empirical estimators based on the geology, the thermotectonic age or the velocity structure of the upper mantle have often been used to affect an estimate to regions where such measurements are absent. On the basis of the assumption that heat flow is strongly related to its geodynamic environment, one may integrate multiple proxies derived from a large body of global geo- logical and geophysical data sets assembled during the past decades; these should help to better capture the variety of present-day settings. This idea is illustrated through two simple empirical methods: both of them are based on a set of examples, where heat flow measure- ments are associated with relevant terrestrial observables such as surface heat production, upper-mantle velocity structure, tectono-thermal age, on a 1◦ × 1◦ grid. To a given target point owning a number of observables, the methods associate a heat flow distribution rather than a deterministic value to account for intrinsic variability and uncertainty within a defined geodynamic environment. The 'best combination method' seeks the particular combination of observables that minimizes the dispersion of the heat flow distribution generated from the set of examples. The 'similarity method' attributes a weight to each example depending on its degree of similarity with the target point. The methods are transparent and are able to handle sets of observables that are not available over the whole Earth (e.g. heat production). The resulting trends of the mean heat flow deduced from the two methods do not differ strongly, but the similarity method shows a better accuracy in cross-validation tests. These tests suggest that the selected proxies have the potential to recover at least partly medium- to large-scale features of surface heat flow. The methods depict the main global trends of low heat flow in stable and ancient regions, and thermal high in active orogens and rift zones. Broad thermal anomalies are outlined in the Sahara and in the tectonically active eastern part of Antarctica. The similarity method estimates a continental heat loss of 13.6 ± 0.8 TW (2σ uncertainty), which is consistent with previous estimates