Interlocking directorates in Spanish banking in the twentieth century

Spanish banking historiography asserts that the largest banks performed in the twentieth century as though they constituted a monopoly. One of their main coordination schemes would have been a network of interlocking bank directors that would include most of the financial firms. Evidence available for the 1920s and 1960s seems to confirm the veracity of this hypothesis. In this paper, more systematic evidence is presented to cover the whole twentieth century with the aim of checking whether these networks persisted over the entire period or they were by-products of temporary situations. Our results show that no general network remained for more than a decade. Therefore, it should be ruled out that interlocking directorates worked as a coordination device of an alleged banking cartel.Monopolization strategies, Interlocking directorates, Spanish banking

Protein crops: Food and feed for the future [Editorial]

Peer reviewedPeer Reviewe

Implementation of key competences: Perceptions of headmasters and physical education teachers

El objetivo del estudio fue conocer las percepciones que tienen sobre la implantación de las Competencias Básicas (CCBB) los equipos directivos y los docentes de Educación Física (EF). Participaron todos los centros de Educación Secundaria de la capital de Burgos (España). Se empleó una metodología mixta, utilizando un cuestionario validado para obtener datos de los directores (N=30) y de los jefes de departamento de EF (N=30) y un estudio de caso único. Los equipos directivos consideran que éstas potencian el aprendizaje del alumnado y favorecen la evaluación. Los docentes valoran la variedad de alternativas en el aula mediante el uso de metodologías cooperativas. La menor edad de los equipos directivos es un factor que influye en su percepción positiva, mientras que la menor experiencia es el factor determinante de esta percepción entre los docentes. El estudio de caso refleja que los profesores de EF de un mismo departamento trabajan de manera diferente las CCBBThe purpose was to assess headmasters and Physical Education teachers’ perceptions on the implementation of Key Competencies (KKCC). All the secondary schools located in Burgos (Spain) agreed to participate. A mixed research design was used. On one hand, an expert validated questionnaire was used to obtain data from all the headmasters (N=30) and all the heads of the Physical Education departments (N=30); on the other hand, a single case study was conducted in one of the schools. Headmasters highlighted that KKCC foster students’ learning and help assess the whole learning process. Teachers underlined that the KKCC promote the use of different learning methods in class and they believed that cooperative learning strategies are needed. Age influenced headmasters’ positive perception on KKCC, and teaching experience influenced teachers’ perceptions. The single case study showed that PE teachers in the same department work differently the KKC

Comparison of ECG T-wave Duration and morphology restitution markers for sudden cardiac death prediction in chronic heart Failure

An index ofT-wave morphology restitution, TMR, has previously shown to be a sudden cardiac death (SCD) predictor in a population of chronic heart failure (CHF) patients. The aim of this study is to compare the predictive value of TMR, T-wave width restitution (TWR), T-peak-to-end (Tpe) morphology restitution (TpeMR) and Tpe duration restitution (TpeR) indices in the same CHF population. Holter ECG recordings from 651 CHF patients of the MUSIC study, including SCD victims and survivors, were analyzed. TMR was significantly correlated with TWR (ρ=0.66), TpeMR (ρ=0.70) and TpeR (ρ=0.42). SCD victims showed significantly higher values of TMR, TWR and TpeMR than the rest of patients, with TMR being the index most strongly associated with SCD (p=0.002, p=0.006 and p=0.011, respectively). TpeR values were only borderline significantly higher in SCD victims (p=0.061). Univariate Cox analysis showed that TMR was the restitution index with the strongest predictive value (hazard ratio (HR) of 1.466, p < 0.001), followed by TWR (HR of 1.295, p=0.005), TpeR (HR of 1.297, p=0.004) and TpeMR (HR of 1.164, p=0.020). In conclusion, considering the predictive value of the four T-wave restitution indices, TMR is the preferred index for SCD risk stratification, followed by TpeMR. However, the marker TWR could also be used for SCD prediction when computational efficiency is an issue

Quantification of T-wave Morphological Variability Using Time-warping Methods

The aim of this study is to quantify the variation of the T-wave morphology during a 24-hour electrocardiogram (ECG) recording. Two ECG-derived markers are presented to quantify T-wave morphological variability in the temporal, dw, and amplitude, da, domains. Two additional markers, dNLw and dNLa, that only capture the non-linear component of dw and da are also proposed. The proposed markers are used to quantify T-wave time and amplitude variations in 500 24-hour ECG recordings from chronic heart failure patients. Additionally, two mean warped T-waves, used in the calculation of those markers, are proposed to compensate for the rate dependence of the T-wave morphology. Statistical analysis is used to evaluate the correlation between dw, dNLw, da and dNLa and the maximum intra-subject RR range, ΔRR. Results show that the mean warped T-wave is able to compensate for the morphological differences due to RR dynamics. Moreover, the metrics dw and dNLw are correlated with ΔRR, but da and dNLa are not. The proposed dw and dNLw quantify variations in the temporal domain of the T-wave that are correlated with the RR range and, thus, could possibly reflect the variations of dispersion of repolarization due to changes in heart rate

An index for T-wave pointwise amplitude variability quantification

The comparison between the pointwise amplitude of different T-waves provides insight into ventricular repolarization liability. However, T-wave pointwise amplitude variability can be confounded by time-domain variability. We, first, compared two algorithms for removing (warping) time-domain variability, one using the original and another one using a transformed T-wave (SRSF). We, next, compared the robustness against noise of two markers, dy and da, of pointwise amplitude variability, after warping the underlying temporal variability with the preferred warping algorithm. dy was obtained from the transformed T-waves while da was proposed in this work and was derived from the original T-waves. We, finally, used the most robust marker to measure the T-wave pointwise amplitude variability between every T-wave recorded during a Tilt test and their mean T-wave. Results showed that the preferred warping algorithm was the SRSF because it is not affected by differences between the amplitudes of the original T-waves. In addition, the marker da presented lower relative error values than dy for every level of noise. The analysis of electrocardiogram records showed that da was significantly lower during the tilt than in supine position (5.5 % vs 6.5 %, p<0.01). In conclusion, da robustly quantifies physiological variabilities of the T-wave amplitude, showing its potential to be used as an arrhythmic risk predictor in future clinical situations

An index for T-wave pointwise amplitude variability quantification

The comparison between the pointwise amplitude of different T-waves provides insight into ventricular repolarization liability. However, T-wave pointwise amplitude variability can be confounded by time-domain variability. We, first, compared two algorithms for removing (warping) time-domain variability, one using the original and another one using a transformed T-wave (SRSF). We, next, compared the robustness against noise of two markers, dy and da, of pointwise amplitude variability, after warping the underlying temporal variability with the preferred warping algorithm. dy was obtained from the transformed T-waves while da was proposed in this work and was derived from the original T-waves. We, finally, used the most robust marker to measure the T-wave pointwise amplitude variability between every T-wave recorded during a Tilt test and their mean T-wave. Results showed that the preferred warping algorithm was the SRSF because it is not affected by differences between the amplitudes of the original T-waves. In addition, the marker da presented lower relative error values than dy for every level of noise. The analysis of electrocardiogram records showed that da was significantly lower during the tilt than in supine position (5.5 % vs 6.5 %, p<0.01). In conclusion, da robustly quantifies physiological variabilities of the T-wave amplitude, showing its potential to be used as an arrhythmic risk predictor in future clinical situations

Influence of heart rate in non-linear HRV indices as a sampling rate effect evaluated on supine and standing

The purpose of this study is to characterize and attenuate the influence of mean heart rate (HR) on nonlinear heart rate variability (HRV) indices (correlation dimension, sample, and approximate entropy) as a consequence of being the HR the intrinsic sampling rate of HRV signal. This influence can notably alter nonlinear HRV indices and lead to biased information regarding autonomic nervous system (ANS) modulation. First, a simulation study was carried out to characterize the dependence of nonlinear HRV indices on HR assuming similar ANS modulation. Second, two HR-correction approaches were proposed: one based on regression formulas and another one based on interpolating RR time series. Finally, standard and HR-corrected HRV indices were studied in a body position change database. The simulation study showed the HR-dependence of non-linear indices as a sampling rate effect, as well as the ability of the proposed HR-corrections to attenuate mean HR influence. Analysis in a body position changes database shows that correlation dimension was reduced around 21% in median values in standing with respect to supine position (p < 0.05), concomitant with a 28% increase in mean HR (p < 0.05). After HR-correction, correlation dimension decreased around 18% in standing with respect to supine position, being the decrease still significant. Sample and approximate entropy showed similar trends. HR-corrected nonlinear HRV indices could represent an improvement in their applicability as markers of ANS modulation when mean HR changes

Fast computation of Lyot-style coronagraph propagation

We present a new method for numerical propagation through Lyot-style coronagraphs using finite occulting masks. Standard methods for coronagraphic simulations involve Fast Fourier Transforms (FFT) of very large arrays, and computing power is an issue for the design and tolerancing of coronagraphs on segmented Extremely Large Telescopes (ELT) in order to handle both the speed and memory requirements. Our method combines a semi-analytical approach with non-FFT based Fourier transform algorithms. It enables both fast and memory-efficient computations without introducing any additional approximations. Typical speed improvements based on computation costs are of about ten to fifty for propagations from pupil to Lyot plane, with thirty to sixty times less memory needed. Our method makes it possible to perform numerical coronagraphic studies even in the case of ELTs using a contemporary commercial laptop computer, or any standard commercial workstation computer.Comment: 17 pages, 9 figures, accepted for publication in Optics Expres