El ente policía y la política de seguridad en Colombia, 2002-2018: Estado, ciudadanía, gobernabilidad y la organización policial

This study analyses security policy in Colombia between 2002 and 2018 and the role the national police force played in this strategy. During the timeframe researched, an unprecedented number of public policies were created. It also constitutes the most critical period of the internal armed conflict between state security forces, guerrillas, paramilitary groups and drug traffickers. A peace process was also initiated at this time, leading to a new phase of transition. As a result, traditional state-centrism models of security have been rethought but not yet implemented. The thesis explores a series of public policies on security, highlighting the important institutional way of dealing with public problems in Colombia, where confusion about different actors’ roles in managing security has persisted. This situation reflects the reductionism surrounding national security, which has been accentuated by the very circumstances surrounding the armed conflict and drug trafficking in the second half of the twentieth century.Political Culture and National Identit

CEO Turnover after Poor Performance: Turnaround or Scapegoating?

This paper explores whether firms that dismiss their Chief Executive Officers (CEOs), due to poor corporate performance, exhibit better performance after the CEO turnover, or whether the CEO dismissal merely serves a scapegoating function. We examine whether companies that were in the eye of the public due to disappointing results recover after dismissing their CEO. We match firms in the same industry, by size, and Altman Z-Score and compare our turnover sample with this matched group of firms that did not dismiss the CEO. Our results suggest that CEO turnovers do not translate into better operating performance, or firm valuation (Tobin’s Q). However, we do find that, after some delay, the market reacts positively to CEO dismissals due to bad performance: Underperforming firms that fire their CEOs exhibit positive and significant abnormal returns, while their counterparts, who retain their CEOs, exhibit negative abnormal returns. Key words: CEO Turnover, Scapegoating, Performanc

Особенности создания импульсных магнитных полей для магнитоуправляемой электрошлаковой плавки

Рассмотрены некоторые особенности создания импульсных магнитных полей для воздействия на кристаллизацию металла в процессе магнитоуправляемой электрошлаковой плавки. Предложены способы интенсификации электромагнитного воздействия на металлургическую ванну, основанные на использовании энергии электрических разрядов емкостных накопителей на внешний магнитный контур. Разработана экспериментальная аппаратура, включающая источник питания для генерирования электрических разрядов энергией до 1850 Дж, и магнитный контур в виде соленоида с дисковыми обмотками, охватывающими кристаллизатор. Изучены характеристики электрических разрядов при различном количестве витков магнитного контура. Показана целесообразность комплексного подхода к интенсификации электромагнитного воздействия посредством оптимизации параметров как источника разрядов, так и соответствующих магнитных контуров. Проведены экспериментальные исследования влияния импульсных магнитных полей на режимы плавки и кристаллизацию металла в процессе выплавки слитков титановых сплавов. Показана возможность при достаточной энергии разрядов и оптимальном количестве витков магнитного контура управлять порционными тепловложениями в процессе плавки, а также кристаллизацией металла слитков. При этом для улучшения качества поверхности слитков предложено воздействие осуществлять сериями импульсов, чередующихся с паузами.Some features of inducing pulsed magnetic fields for acting on metal solidification during magnetically-controlled electroslag melting are considered. Methods of intensification of electromagnetic impact on metallurgical bath are proposed, which are based on application of energy of capacitive storage electric discharges to external magnetic circuit. Experimental system has been developed, including a power source for generation of electric discharges with up to 1850 J energy, and a magnetic circuit in the form of a solenoid with disc windings enclosing the mould. Characteristics of electric discharges at different number of magnetic circuit turns have been studied. The paper shows the rationality of an integrated approach to electromagnetic impact intensification through optimization of parameters of both the discharge source and the respective magnetic circuits. Experimental investigations of the influence of pulsed magnetic fields on metal melting and solidification modes during melting of titanium alloy ingots have been performed. Ability to control discrete heat input during melting, as well as ingot metal solidification at sufficient discharge energy and optimum number of magnetic circuit turns, is demonstrated. To improve ingot surface quality, it is proposed to apply the impact in the form of series of pulses alternating with pauses

Radiative Mechanism to Light Fermion Masses in the MSSM

In a previous work we have showed that the ${\cal Z}_{2}^{\prime}$ Symmetry, imply that the light fermions, the electron and the quarks, $u,d$ and $s$, get their masses only at one loop level. Here, we considere the more general hypothesis for flavour mixing in the sfermion sector in the MSSM. Then, we present our results to the masses of these light fermions and as a final result we can explain why the $s$ quark is heavier than the $u,d$ quarks. This mechanism is in agrement with the experimental constraint on the sfermion's masses values.Comment: 22 pages, 8 figures, TeX mistakes corrected, accepted for publication in JHE

Ionic liquids breakdown by Fenton oxidation

Fenton oxidation has proved to be an efficient treatment for the degradation of ionic liquids (ILs) of different families viz. imidazolium, pyridinium, ammonium and phosphonium, in water. The intensification of the process, defined as the improvement on the efficiency of H2O2 consumption, by increasing the temperature is necessary to avoid high reaction times and the need of large excess of H2O2. In this work, temperatures within the range of 70-90°C have been used, which allowed an effective breakdown of the ILs tested (1 g L-1 initial concentration) with the stoichiometric amount of H2O2 and a relatively low Fe3+dose (50 mg L-1). Under these conditions conversion of the ILs was achieved in less than 10 min, with TOC reductions higher than 60% upon 4 h reaction time, except for the phosphonium IL. The remaining TOC corresponded mainly to short-chain organic acids. The treatment reduced substantially the ecotoxicity up to final values below 0.01 TU in most cases and a significant improvement of the biodegradability was achieved. Upon Fenton oxidation of the four ILs tested hydroxylated compounds of higher molecular weight than the starting ILs, fragments of ILs partially oxidized and short-chain organic acids were identified as reaction by-products. Reaction pathways are proposedThis research has been supported by the Spanish MICINN through the projects CTQ2008-03988 and CTQ2010-14807 and by the CM through the project S-2009/AMB-158

Identifying the Structure of Non-Linear Dynamic Systems Using Multiobjective Genetic Programming

A method for identifying the structure of non-linear polynomial dynamic models is presented. This approach uses an evolutionary algorithm, Genetic Programming, in a multiobjective fashion to generate global models which describe the dynamic behaviour of the non-linear system under investigation. The introduction of the validation stage of system identification into the multiobjective tool is also explored, in order to direct the identification process to a set of global models of the system

Willingness to pay for beach ecosystem services: the case study of three Colombian beaches

Throughout the scientific literature, beaches have been regarded as very valuable ecosystems for the tourism industry; however, these ecosystems provide multiple direct and indirect benefits beyond tourism. This paper accounts for the results from a Willingness to Pay (WTP) study using data from 425 respondents at three beaches in the Colombian Caribbean Region. Out of the respondents from the three beaches, over 70% expressed a positive WTP to maintain Beach Ecosystem Services (BES) beyond tourism purposes. At two beaches, the payment amount was 3.40 US$/month, while at the third beach the payment amount was 6.80 US$/month. Beach environmental quality seemed to be an important aspect regarding the payment amount. It is highlighted that WTP in beaches did not depend on economic variables such as income or employment, whereas variables related to perception had a determining impact. WTP for BES was defined by interest in environmental issues and concerns about ecosystem services loss. The results offered hereto could provide support to decision makers through quantitative information on social preferences regarding beach improvement projects policies, if several reflections are considered