Top management team heterogeneity and firm performance

At this research will try to analyze the direct relation that the Upper Echelons Theory establishes between the diversity of the demographic characteristics of the top management teams and the performance. As Hambrick and Mason (1984: 193), we consider that “organizational outcomes are viewed as reflections of the values and cognitive bases of powerful actors in the organization: the top managers”. Moreover, “managerial characteristics of these top managers are indicators of firm performance” (1984: 196). Premise that we will try to test in this research across the empirical contrast of five hypotheses and a theoretical model. The results of our research reveal us how of five raised hypotheses, three are fulfilled in its entirety, one was fulfilling partially to the being the sense of the existing relation the inverse one to the raised one, and one is not fulfilled

On the observation of magnetic events on broad-band seismometers

The objective of this contribution is to get new insights into the effects of magnetic field variations of natural and anthropogenic origin on broad-band seismic stations. Regarding natural sources of magnetic perturbations, we have investigated if the Sudden Storm Commencements (SSC) cataloged during the 24th solar cycle (2008-2019) can be systematically identified in broad-band seismic stations distributed worldwide. The results show that the 23 SSC events with a mean amplitude above 30 nT and most of those with lower energy but still clearly identified in the magnetometer detection network can be observed at broad-band stations' network using a simple low-pass filter. Although the preliminary impulse of those signals is usually stronger at stations located at high latitudes, major SSC are observed at seismic stations distributed worldwide. Regarding anthropogenic sources, we focus on the short period seismic signals recorded in urban environments which are correlated with the activity of the railway transportation system. We have analyzed collocated measurements of electric field and seismic signals within Barcelona, evidencing that significant changes in the electric field following the activity of the transportation systems can be attributed to leakage currents transmitted to the soil by trains. During space weather events, electric currents in the magnetosphere and ionosphere experience large variations inducing telluric currents near the Earth surface, which in turn generate a secondary magnetic field. In the case of underground trains, leakage currents are transmitted to the soil, which in turn can result in local variations in the magnetic field. The observed signals in modern seismometers can be related to the reaction of the suspension springs to these magnetic field variations or to the effect of the magnetic field variations on the force transducers used to keep the mass fixed

Top management teams in the Spanish global business environment: an empirical study

The use of top management teams is expanding in response to the turbulence and complexity of the global business environment (Cohen and Bailey, 1997). To perform well among growing competition greater efficiency is required and top management teams bring not only more resources into the organization but also different kinds of skills and knowledge to success it. Top management teams are very common and crucial subject of study in North American researches. Nerveless, in the Spain context exist a big empty in the literature. This absence is the main motivation for the current study

Frequency measurement under non-sinusoidal conditions

Frequency measurement is an important issue in electrical engineering. Electric power systems have become increasing complex over the last decade. The use of distributed generation, the connection of non-linear loads and the presence of unexpected system faults are the main causes of frequency variations. In addition, power quality includes frequency as an important index. From a hardware instrumentation point of view, frequency measurement has different requirements: i.) Large power systems have slow frequency variation due to the high inertia of the overall network. This kind of problem requires frequency measuring methods capable of detecting small and also slow frequency variations. ii.) Small power systems can have frequency variation due to their reduced short-circuit power capacity. This type of problem requires fast methods with the capacity to detect large frequency variations. There are different groups of methods intended for frequency measurement. The methods can be compared in terms of computation and dynamic response, especially when the main voltage is disturbed. This research work focuses on frequency measurement under non-sinusoidal conditions. The paper studies the behaviour of a modified version of Sezi's method and its hardware implementation using a microcontroller. This system can be used for frequency measurement or as a synchronized sampling source in harmonic measurement (e.g. EN 61000-4-7) The fast time response of the system enables it to be used in almost all kinds of application: small and slow frequency variations; frequency triggering in power system protection and power quality index characterisation