Time Series Analysis

We provide a concise overview of time series analysis in the time and frequency domains, with lots of references for further reading.time series analysis, time domain, frequency domain

Inhaled Sevoflurane Produces Better Delayed Myocardial Protection at 48 Versus 24 Hours After Exposure

Ischemia preconditioning produces a delayed window of cardioprotection against subsequent ischemia and reperfusion injury. Contradictory results have been reported regarding the ability of inhaled anesthetics to produce similar effects. Our investigation was designed to test whether inhaled sevoflurane is capable of producing a delayed window of anesthetic preconditioning and to compare the differences at 24 and 48 h after exposure. Male Fischer-344 rats, 2-4 mo old, were exposed to sevoflurane (2.5% for 60 min). Twenty-four or 48 h after exposure, the hearts were isolated and perfused for 30 min (equilibration) followed by 25 min of ischemia and then 60 min of reperfusion. Control hearts received no treatment before ischemia. Left ventricular (LV) function, creatine kinase (CK), and infarct size (IS) were measured. Nuclear magnetic resonance was used to measure Na+(i), [Ca2+]i, and pH(i). There was improved LV function and significant reduction in IS and CK and in both the 24- and 48-h delayed groups compared with the controls. There was also a significant recovery of LV function and reduction in IS and CK in the 48-h group when compared with the 24-h group. There was significant adenosine triphosphate preservation in both the 24- and 48-h groups, as well as a significant reduction in acidosis, [Ca2+]I, and Na+(i) in response to ischemia in both the groups versus the control. Sevoflurane is capable of producing a delayed window of preconditioning, and it takes more than 24 h to produce maximal protective effects

The Economic Impact of Immigration in Germany

We have combined a simple demographic model and the 58 sector econometric simulation and forecasting model INFORGE (Interindustry Forecasting Germany) which has been successfully used in different areas, e.g. modelling the effects of CO2 taxes and the liberalisation of the IT market on the German economy. The demographic model gives a forecast of the female and male age structure till the year 2010. INFORGE is part of the INFORUM International System that links 13 national Input-Output models on the sectoral level via export and import flows as well as the corresponding foreign trade prices. The model has a high degree of endogenization. Only some tax rates and the world market variables of the international INFORUM system are given exogenously. The high degree of endogenization has the advantage that in simulations the effects are depicted completely. The labour supply is modelled using the population module. The occupied population can be calculated by linking the age structure to the labour force participation rate of women and men for different age groups. So we have the possibility to simulate the effects of different migration scenarios on the German economy, assumed the structure of migration is constant over time

Wirtschaftskrise: Schnelle Erholung oder lang anhaltende Depression? Bandbreiten der mittelfristigen Wirtschaftsentwicklung in Deutschland

Angesichts der globalen Finanz- und Wirtschaftskrise ist die Unsicherheit über die zukünftige Entwicklung der deutschen Volkswirtschaft verglichen mit der Vergangenheit außerordentlich hoch. Langfristige Projektionen der wirtschaftlichen Entwicklung sind heute nur unter erheblichem Aufwand seriös möglich. Vor diesem Hintergrund zielt dieser Beitrag darauf, Leitplanken im Prognosenebel zu beschreiben. Mit dem Modell INFORGE werden auf Basis einer Prognose für das Jahr 2009, die die Konjunkturpakete der Bundesregierung berücksichtigt, zwei denkbare mittelfristige Entwicklungslinien in einem konsistenten gesamtwirtschaftlichen Rahmen beschrieben, die sich nur durch Annahmen über die weltwirtschaftliche Entwicklung in den Jahren 2010 bis 2013 unterscheiden. Das optimistische Szenario geht davon aus, dass sich die Weltwirtschaft im Jahr 2010 durch die massiven Konjunkturprogramme der führenden Industrienationen und durch Etablierung einer neuen Finanzmarktarchitektur schnell erholen wird und damit auch die deutschen Exporte wieder deutlich wachsen werden. In der pessimistischen Variante vertieft sich die Weltwirtschaftskrise im kommenden Jahr weiter. Selbst wenn die Weltwirtschaft danach langsam wieder Tritt fasst, wird es bis 2014 dauern, bis die deutschen Exporte wieder das Niveau des Jahres 2008 erreicht haben werden. Die untersuchte Fragestellung ist so komplex, dass intuitive Erklärungen durch scharfes Nachdenken nicht mehr möglich sind. Nur umfassende und zugleich ausreichend differenzierte Totalmodelle wie INFORGE stellen sicher, dass die wesentlichen Zusammenhänge und Rückkopplungsschleifen erfasst und nachvollzogen werden können. Die Ergebnisse sind einerseits ernüchternd und andererseits beruhigend: Auch im besten Fall ist Deutschland massiv von der Krise betroffen. Alle Bemühungen zur Konsolidierung der öffentlichen Haushalte sind durch die Krise zunichte gemacht. Für Wahlgeschenke ist kein Spielraum. Vielmehr ist es Aufgabe der Politik in der kommenden Legislaturperiode, die Binnennachfrage zu stärken und trotzdem die Verschuldung zurückzuführen. Umgekehrt droht in Deutschland selbst unter sehr ungünstigen Bedingungen keine unbeherrschbare Situation. Auf dem Arbeitsmarkt ist kein dramatischer Anstieg der Arbeitslosigkeit über das noch vor wenigen Jahren erreichte Niveau hinaus zu erwarten. Die Neuverschuldung erreicht, bezogen auf das Bruttoinlandsprodukt, keine neuen Höchststände, sodass die Regierung auch im kommenden Jahr mit einem Konjunkturpaket III noch einmal handeln könnte

Simultaneous multislice acquisition with multi-contrast segmented EPI for separation of signal contributions in dynamic contrast-enhanced imaging

We present a method to efficiently separate signal in magnetic resonance imaging (MRI) into a base signal S0, representing the mainly T1-weighted component without T2*-relaxation, and its T2*-weighted counterpart by the rapid acquisition of multiple contrasts for advanced pharmacokinetic modelling. This is achieved by incorporating simultaneous multislice (SMS) imaging into a multi-contrast, segmented echo planar imaging (EPI) sequence to allow extended spatial coverage, which covers larger body regions without time penalty. Simultaneous acquisition of four slices was combined with segmented EPI for fast imaging with three gradient echo times in a preclinical perfusion study. Six female domestic pigs, German-landrace or hybrid-form, were scanned for 11 minutes respectively during administration of gadolinium-based contrast agent. Influences of reconstruction methods and training data were investigated. The separation into T1- and T2*-dependent signal contributions was achieved by fitting a standard analytical model to the acquired multi-echo data. The application of SMS yielded sufficient temporal resolution for the detection of the arterial input function in major vessels, while anatomical coverage allowed perfusion analysis of muscle tissue. The separation of the MR signal into T1- and T2*-dependent components allowed the correction of susceptibility related changes. We demonstrate a novel sequence for dynamic contrast-enhanced MRI that meets the requirements of temporal resolution (Δt < 1.5 s) and image quality. The incorporation of SMS into multi-contrast, segmented EPI can overcome existing limitations of dynamic contrast enhancement and dynamic susceptibility contrast methods, when applied separately. The new approach allows both techniques to be combined in a single acquisition with a large spatial coverage

Developing country firms and the challenge of corruption: do company commitments mirror the quality of national-level institutions?

Corruption is an important topic for management scholars and practitioners. Given the rise to economic prominence of firms from developing countries, this paper investigates how developing country firms engage with this challenge. Based on a content analysis of 191 codes of conduct, issued by firms from 18 developing countries, we first investigate what anti-corruption commitments developing country firms make in their codes of conduct; we then determine contextual factors at national business system level that drive differences in firm engagement. We provide evidence for a “mirror view” of corporate social responsibility, according to which companies match the quality of national-level institutions in their own anti-corruption commitments. This result stands in contrast to the basic expectation underlying the concept of corporate social responsibility that companies step in to close governance gaps and address wider societal-level challenges. Our findings thus highlight limitations to purely private governance mechanisms aimed at combatting corruption

Global Multisector / Multicountry 3 - E Modelling: From COMPASS to GI FORS

The global dimension of environmental policy, which has become a subject of international policy with the concrete discussion of targets and instruments, constitutes a huge information gap for environmental policy. The authors postulate, that this can only be filled by the application of global economic environmental models, which have to meet certain requirements: A multisector and multicountry system with global coverage and bilateral trade linkage with econometrically estimated parameters is needed. The authors present the system COMPASS (Comprehensive Model of Policy Assessment) and the improved system GINFORS (Global Interindustry Forecasting System), which is just being constructed based on the experiences made with COMPASS. A discussion of the application of GINFORS in the EU project MOSUS (Modelling Opportunities and Limits for Restructuring Europe towards Sustainability) gives an impression of the power of the model to analyze global economic environmental questions and to forecast important environmental indicators

Global Multisector/ Multicountry 3- E Modelling : from COMPASS to GINFORS

La dimensión global de la política medioambiental, que se ha convertido en una cuestión de política internacional con la discusión concreta de objetivos e instrumentos, supone un enorme vacío de información para esa política medioambiental. Los autores postulan que éste solo puede cubrirse mediante la aplicación de modelos ambientales económicos globales, que habrán de cumplir ciertos requisitos: se necesita un sistema multi-sector y multi-país con cobertura global y con vínculos de comercio bilateral a parámetros estimados econométricamente. Los autores presentan el sistema COMPASS (Comprehensive Model of Policy Assessment) y el mejorado sistema GINFORS (Global Interindustry Forecasting System), que se está construyendo en base a la experiencia alcanzada con COMPASS. El análisis de la aplicación de GINFORS el proyecto MOSUS (Modelling Opportunities and Limits for Restructuring Europe towards Sustainability) de la UE da idea del potencial del modelo para estudiar asuntos ambientales y económicos globales y para predecir importantes indicadores ambientales. ________________________________________The global dimension of environmental policy, which has become a subject of international policy with the concrete discussion of targets and instruments, constitutes a huge information gap for environmental policy. The authors postulate, that this can only be filled by the application of global economic environmental models, which have to meet certain requirements: A multisector and multicountry system with global coverage and bilateral trade linkage with econometrically estimated parameters is needed. The authors present the system COMPASS (Comprehensive Model of Policy Assessment) and the improved system GINFORS (Global Interindustry Forecasting System), which is just being constructed based on the experiences made with COMPASS. A discussion of the application of GINFORS in the EU project MOSUS (Modelling Opportunities and Limits for Restructuring Europe towards Sustainability) gives an impression of the power of the model to analyze global economic environmental questions and to forecast important environmental indicators