1,011 research outputs found

    Forecasting Bonds Yields in the Brazilian Fixed Income Market

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    This paper studies the predictive ability of a variety of models in forecasting the yield curve for the Brazilian fixed income market. We compare affine term structure models with a variation of the Nelson-Siegel exponential framework developed by Diebold and Li (2006). Empirical results suggest that forecasts made with the latter methodology are superior and appear accurate at long horizons when compared to different benchmark forecasts. These results are important for policy makers, portfolio and risk managers. Further research could study the predictive ability of such models in other emerging markets.

    Where and Who? Automatic Semantic-Aware Person Composition

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    Image compositing is a method used to generate realistic yet fake imagery by inserting contents from one image to another. Previous work in compositing has focused on improving appearance compatibility of a user selected foreground segment and a background image (i.e. color and illumination consistency). In this work, we instead develop a fully automated compositing model that additionally learns to select and transform compatible foreground segments from a large collection given only an input image background. To simplify the task, we restrict our problem by focusing on human instance composition, because human segments exhibit strong correlations with their background and because of the availability of large annotated data. We develop a novel branching Convolutional Neural Network (CNN) that jointly predicts candidate person locations given a background image. We then use pre-trained deep feature representations to retrieve person instances from a large segment database. Experimental results show that our model can generate composite images that look visually convincing. We also develop a user interface to demonstrate the potential application of our method.Comment: 10 pages, 9 figure

    A robust control scheme for flexible arms with friction in the joints

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    A general control scheme to control flexible arms with friction in the joints is proposed in this paper. This scheme presents the advantage of being robust in the sense that it minimizes the effects of the Coulomb friction existing in the motor and the effects of changes in the dynamic friction coefficient. A justification of the robustness properties of the scheme is given in terms of the sensitivity analysis

    Spanish anarchist engagements in electoralism: from street to party politics

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    The eruption of the Spanish 15M movement in 2011 was marked by a high degree of political participation and creative experimentation. The political repertoire has constantly been re-evaluated, with methods revised and evolving, from the occupation of public spaces to the recent creation of new constitutional parties. One of the key aspects of these tactical revisions has been the involvement of anarchist actors in an experimental process of engagement in electoral processes, a method of political engagement anarchists standardly oppose. Our study identifies the motivations and theoretical justifications that have recently led libertarian activists to take the electoral path. This paper stands in the small but growing tradition of works that examine the recent phenomenon of new parties built by ‘street’ activists, but uniquely concentrates on a detailed case study of the anarchist actors linked to the platform Castelló en Moviment (CsM). It thus describes the anarchist influence in recent electoral developments, identifies proponents’ justifications for engaging in these previously rejected methods and highlights some of the doubts raised about the electoral experiment

    Untersuchung zur kardialen Belastung im Altherren-Fußball und klinischen Bedeutung belastungsinduzierter Anstiege der kardialen Laborparameter Troponin und B-Typ Natriuretisches Peptid

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    Trotz der heutigen Kenntnis über den Nutzen regelmäßiger körperlicher Aktivität für die Aufrechterhaltung der Gesundheit kommt es immer wieder zu wissenschaftlichen und öffentlichen Diskussionen über mögliche kardiale Gefährdungen durch Sport. Insbesondere plötzliche Todesfälle vermeintlich gesunder Sportler geraten häufig in den Fokus der Medien und Öffentlichkeit. Zudem besteht auch in der Wissenschaft Uneinigkeit zu möglichen Schäden durch Sport, da mehrfach nachgewiesen werden konnte, dass intensive oder erschöpfende körperliche Belastungen zu einem Anstieg der kardialen Marker Troponin und B-Typ Natriuretisches Peptid (BNP) führen können, die als laborchemische Goldstandards in der akuten Herzinfarkt-Diagnostik (Troponin) bzw. Herzinsuffizienz-Diagnostik (BNP) eingesetzt werden. Anfang 2012 wurde in Deutschland ein bundesweites Register zur Erhebung plötzlicher kardialer Todesfälle (SCD-Deutschland) eingeführt, dem Fälle eines Sport-assoziierten plötzlichen Herztodes gemeldet werden können. In diesem Register wurden von 2012 bis 2014 insgesamt 144 plötzliche kardiale Todesfälle in Zusammenhang mit verschiedenen Sportarten verzeichnet. Den größten Anteil dieser Sport-assoziierten plötzlichen kardialen Todesfälle stellt der Fußball. Zudem ereignete sich ein Großteil dieser Fälle bei Spielern, die älter als 40 Jahre alt waren. Es konnte darüber hinaus gezeigt werden, dass in über 90 % der Sport-assoziierten Todesfälle keine professionellen Athleten, sondern Freizeitsportler betroffen waren. Dem Altherren-Fußball kommt deshalb eine besondere Bedeutung zu. Durch eine hohe Anzahl an Teilnehmern in Deutschland, die ein erhöhtes Alter sowie eine vermehrte Anzahl an kardiovaskulären Risikofaktoren präsentieren, könnte die Kombination mit einer körperlichen Anstrengung ein größeres Risiko für einen Sport-assoziierten plötzlichen Herztod bedeuten. Allerdings wurden in der Vergangenheit noch keine Studien durchgeführt, welche die kardiale Belastung der Spieler während eines Altherren- Fußballspieles durch Bestimmung kardialer Marker erfasst haben, um das kardiovaskuläre Risiko im Altherren-Fußball näher zu untersuchen. Ziel dieser Studie war es deshalb zu untersuchen, welches Ausmaß die kardiale Belastung von Fußballspielern im Altherren-Bereich während eines Fußballspieles annimmt. Dazu wurden im Jahr 2015 insgesamt 112 Altherren-Fußballspieler des saarländischen Fußballbundes in 6 verschiedenen Spielen untersucht. Die erfolgte Belastung bestand aus zwei 30-minütigen Halbzeiten, die von einer 15-minütigen Pause unterbrochen waren. Pro Mannschaft standen 11 Spieler auf dem Spielfeld, die jederzeit ohne Wechsellimit ausgetauscht werden konnten. Die kardialen Marker Troponin I und BNP wurden sowohl vor Spielbeginn, als auch innerhalb von 30 Minuten nach Belastungsende bestimmt. Zur Untersuchung des Herzrhythmus und zur Aufzeichnung von Herzrhythmusstörungen, signifikanten Endstreckenveränderungen sowie weiterer Parameter, wurde jeder Spieler mit einer unter dem Trikot tragbaren EKG-Weste der Firma SenseCore ausgestattet. Zur Erhebung einer umfassenden Anamnese, wurde vor dem Spiel von jedem Teilnehmer ein Gesundheitsfragebogen unter ärztlicher Aufsicht und gegebenenfalls Rücksprache ausgefüllt und nachfolgend mit allen Probanden telefonisch ein ausführliches Anamnesegespräch durchgeführt. Die Troponin I-Konzentration zeigte nach Spielschluss einen höchst signifikanten Anstieg (p = 0,001). Insgesamt kam es bei 33 der 112 untersuchten Altherren-Fußballern zu einem Überschreiten des Cut-Off-Wertes von 5 ng/l. Bei insgesamt 30 % der Spieler kam es somit nach Spielschluss zu einem Überschreiten der Troponin I-Konzentration über den von Chapman et al. sowie Shah et al. empfohlenen Grenzwert von 5 ng/l, in Folge dessen Patienten aus einer Notaufnahme nicht entlassen werden sollten, da Nachkontrollen des Troponin-Wertes zum Ausschluss eines akuten Myokardinfarkts empfohlen werden. Auch die BNP-Konzentration der Teilnehmer stieg im Median von 27 pg/ml (21 / 41) auf 36 pg/ml (26 / 46) nach erfolgter Belastung höchst signifikant an (p < 0,001). Bei insgesamt 5 % der Teilnehmer konnte darüber hinaus nach dem Spiel eine BNP- Konzentration über dem Cut-Off-Wert einer Herzinsuffizienz von 100 pg/ml beobachtet werden. Ein Zusammenhang zwischen den Anstiegen von Troponin I und BNP nach Belastung zeigte sich in dieser Untersuchung nicht (p = 0,967). Schlussfolgernd ist aufgrund der vorliegenden Ergebnisse festzustellen, dass Fußballspiele im Altherren-Bereich bei 30 % der Spieler zu signifikanten Erhöhungen von Troponin I und bei 5 % der Spieler zu BNP-Anstiegen führen können und somit eine hohe kardiale Belastung bedeuten. Diese Anstiege sind marginal, jedoch liegen sie über den von Chapman et al. und Shah et al. berichteten Grenzwerten, die eine weitere Abklärung in Notaufnahmen bedingen würden. Die vorliegende Studie unterstreicht deshalb, dass regelmäßige sportkardiologische Vorsorgeuntersuchungen im AH-Fußball unter Berücksichtigung der in dieser Untersuchung vorliegenden kardialen Risikofaktoren in Kombination mit der gegeneben kardialen Belastung zu empfehlen sind.Despite today's knowledge concerning the benefits of regular physical activity for the maintenance of health, scientific and public discussions about possible cardiac risks due to sports are still taking place. Sudden deaths of supposedly healthy athletes in particular come into the focus of the media and the public with regularity. In addition, there is disagreement in science about possible damage caused by sports, since it has been proven that intensive or exhaustive physical exercise can lead to an increase of the cardiac markers troponin and B-type natriuretic peptide (BNP), which are used as gold standard in laboratory diagnosis of acute coronary syndrome (troponin) or diagnosis of heart failure (BNP). In 2012, a nationwide register for sudden cardiac deaths (SCD-Germany) was introduced in Germany, to which cases of exercise associated sudden cardiac deaths can be reported. By 2014, a total of 144 sudden cardiac deaths related to various sports were recorded in this register. The largest proportion of these exercise associated sudden cardiac deaths is represented by football. In addition, a large proportion of these cases occurred among players over 40 years of age. It was also shown that in over 90 % of exercise associated deaths, not professional but recreational athletes were affected. Veteran football therefore is of particular significance. Due to a high number of participants in Germany who present an increased age and an elevated quantity of cardiovascular risk factors, the combination with physical exertion could result in a greater risk of sudden cardiac death associated with sports. However, no studies have been carried out in the past to examine the cardiac load of players during a veteran football match by determining cardiac markers in order to assess the cardiovascular risk in veteran football. The aim of this study was therefore to investigate the extent to which the cardiac load of veteran football players amounts during a football match. In 2015, a total of 112 veteran football players of the Saarland Football Association were examined in 6 different matches. Each match consisted of two 30-minute half-times, interrupted by a 15-minute break. There were 11 players per team on the field, who could be replaced at any time without a change limit. The cardiac markers troponin I and BNP were determined both before the game and within 30 minutes after. For examination of the heart rhythm and recording of cardiac 5 arrhythmias, significant terminal ST-segment deviations as well as other parameters, each player was equipped with an ECG-vest of the company SenseCore, which can be worn under the jersey. In order to establish a comprehensive anamnesis, each participant completed a health questionnaire before the game and subsequently a detailed anamnesis interview with all veteran football players was conducted. The troponin I concentration showed a highly significant increase after the end of the game (p = 0.001). In total, 33 of the 112 veteran footballer players examined exceeded the 5 ng/l cut-off value. Thus, for 30 % of the players the troponin I concentration exceeded the threshold of 5 ng/l recommended by Chapman et al. and Shah et al. at the end of the game, as a result of which patients should not be discharged from an emergency room, as follow-up checks of the troponin value are recommended to rule out acute myocardial infarction. The median BNP concentration of the participants also increased significantly from 27 pg/ml (21 / 41) to 36 pg/ml (26 / 46) after exercise (p < 0.001). In a total of 5 % of the participants, a BNP concentration above the cut-off value of 100 pg/ml used in heart failure diagnostics could also be observed after the game. A correlation between the increase of troponin I and BNP after exercise was not found in this study (p = 0.967). On the basis of the obtained results, it can be concluded that football matches in veteran football can lead to significant increases in troponin I for 30 % of the players and to increases in BNP for 5 % of the players and thus to a high cardiac load. These increases are marginal, but they exceed the limits reported by Chapman et al. and Shah et al., which would require further clarification in emergency rooms. Taking into account the cardiac risk factors present in this study in combination with the given cardiac load, this study underlines the importance of regular preventive medical check-ups in veteran football

    Characterization and functionalization by sol–gel route of SiC foams

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    Ceramic foam materials are commonly used for various applications, including catalyst supports or solar receivers. SiC foams are good candidates for the latter application as solar receivers. Its efficiency is directly related to the geometry, which can be evidenced by X-ray microtomography, and optical properties of the receiver. A promising route to add functionalities with homogenous and adhering oxide coatings onto complex SiC foams in a single step process is proposed. This oxide synthetic process is derived from the Pechini method. Foams are fully impregnated by precursor sols with a controlled viscosity making a thin and totally covering coating

    Choking dynamic of highly swirled flow in variable nozzle radial turbines

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    [EN] This paper presents the results of a computational investigation of the aerodynamic choking mechanism in a variable geometry turbine, which is widely used in automotive turbocharging. RANS and URANS numerical simulations were carried out for two stator vane positions, 10% and 30% opening at different speeds and several other operating conditions to observe the establishment of choked flow and rotorstator interactions. When the stator vanes are at a closed position and high-pressure ratio, a shock wave is developed on the suction side of the stator vane; moreover, the effective area extends toward the rotor inlet. The shock losses of a fluid particle upstream of the rotor are related to the number of shocks that the particle goes through. The pressure losses are high close to the stator vanes and start to decrease toward the center of the vaneless space until they start to increase close to the rotor. The interaction between the rotor and stator creates shocks waves with an intensity depending on the rotor¿s leading edge position and the rotational speed. The pressure profile of the rotor blade under this circumstance is also affected, especially at high rotational speeds, when important load fluctuations may affect the integrity of the blades.The work has been partially supported by the ¿Subprograma de Formación de Profesorado Universitario (FPU)¿. Ministerio de Universidades. FPU18/02628 and by the ¿FPI Subprograma 2¿. Universitat Politècnica de València. PAID-10-18Tiseira, A.; Dolz, V.; Inhestern, LB.; Echavarria-Olaya, JD. (2022). Choking dynamic of highly swirled flow in variable nozzle radial turbines. Aerospace Science and Technology. 122:1-13. https://doi.org/10.1016/j.ast.2022.10739611312

    Visualization of large distributed data in Neuroscience

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    The Human Brain Project is an exemplary case of data driven science
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