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

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 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

RNA-seq analysis reveals TRPC genes to impact an unexpected number of metabolic and regulatory pathways

The seven-member transient receptor potential canonical genes (TRPC1-7) encode cation channels linked to several human diseases. There is little understanding of the participation of each TRPC in each pathology, considering functional redundancy. Also, most of the inhibitors available are not specifc. Thus, we developed mice that lack all of the TRPCs and performed a transcriptome analysis in eight tissues. The aim of this research was to address the impact of the absence of all TRPC channels on gene expression. We obtained a total of 4305 diferentially expressed genes (DEGs) in at least one tissue where spleen showed the highest number of DEGs (1371). Just 21 genes were modifed in all the tissues. Performing a pathway enrichment analysis, we found that many important signaling pathways were modifed in more than one tissue, including PI3K (phosphatidylinositol 3-kinase/protein kinase-B) signaling pathway, cytokine-cytokine receptor interaction, extracellular matrix (ECM)-receptor interaction and circadian rhythms. We describe for the frst time the changes at the transcriptome level due to the lack of all TRPC proteins in a mouse model and provide a starting point to understand the function of TRPC channels and their possible roles in pathologies.Fil: Formoso, Karina. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Susperreguy, Sebastian. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Freichel, Marc. Universität Heidelberg; AlemaniaFil: Birnbaumer, Lutz. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentin

Ability of Black-Box Optimisation to Efficiently Perform Simulation Studies in Power Engineering

In this study, the potential of the so-called black-box optimisation (BBO) to increase the efficiency of simulation studies in power engineering is evaluated. Three algorithms ("Multilevel Coordinate Search"(MCS) and "Stable Noisy Optimization by Branch and Fit"(SNOBFIT) by Huyer and Neumaier and "blackbox: A Procedure for Parallel Optimization of Expensive Black-box Functions"(blackbox) by Knysh and Korkolis) are implemented in MATLAB and compared for solving two use cases: the analysis of the maximum rotational speed of a gas turbine after a load rejection and the identification of transfer function parameters by measurements. The first use case has a high computational cost, whereas the second use case is computationally cheap. For each run of the algorithms, the accuracy of the found solution and the number of simulations or function evaluations needed to determine the optimum and the overall runtime are used to identify the potential of the algorithms in comparison to currently used methods. All methods provide solutions for potential optima that are at least 99.8% accurate compared to the reference methods. The number of evaluations of the objective functions differs significantly but cannot be directly compared as only the SNOBFIT algorithm does stop when the found solution does not improve further, whereas the other algorithms use a predefined number of function evaluations. Therefore, SNOBFIT has the shortest runtime for both examples. For computationally expensive simulations, it is shown that parallelisation of the function evaluations (SNOBFIT and blackbox) and quantisation of the input variables (SNOBFIT) are essential for the algorithmic performance. For the gas turbine overspeed analysis, only SNOBFIT can compete with the reference procedure concerning the runtime. Further studies will have to investigate whether the quantisation of input variables can be applied to other algorithms and whether the BBO algorithms can outperform the reference methods for problems with a higher dimensionality

A relaxation method for large eigenvalue problems, with an application to flow stability analysis

International audienceLinear stability analysis of fluid flows usually involves the numerical solution of large eigenvalue problems. We present a spectral transformation allowing the computation of the least stable eigenmodes in a prescribed frequency range, based on the filtering of the linearized equations of motion. This "shift-relax" method has the advantage of low memory requirements and is therefore suitable for large two- or three-dimensional problems. For demonstration purposes, this new method is applied to compute eigenmodes of a compressible jet