EVIDENCIA ADICIONAL DEL EFECTO SOBRE-REACCIÓN EN EL MERCADO ESPAÑOL DE CAPITALES

In a previous work, Forner and Marhuenda (2001) find that the contrarian strategy, thatis, the forming of a zero-investment portfolio that buys the stocks that have performed poorly inthe past (losers) and sells those that have performed well (winners), does not yield abnormallypositive returns in the future when three-years periods are analysed, so there does not seem to beany over-reaction phenomenon in the Spanish Stock Market. In this work, additional empiricalevidence is presented with regard to the behaviour of the contrarian strategy, and someimprovements have been made to certain issues. On one hand, the number of contrarianstrategies analysed is increased to four, depending on how the winners and losers are selected:Either three- or five-year formation periods and cumulative returns obtained from an additive ora buy-and-hold procedure. On the other hand, two methodological issues are enhanced: (i) thelong-run returns of the portfolios are calculated with both the additive and the buy-and-holdprocedures, and (ii) the methodologies used allow us to work with overlapping test-periods.Finally, a seasonal analysis of the behaviour of the contrarian strategy is made with a cleardistinction being made between January and the rest of the year. This more exhaustive studyshows that, in principle, we can not discard the existence of an over-reaction effect in theSpanish Stock market when we observe five-year time horizons. En un trabajo previo, Forner y Marhuenda (2001) obtienen que la estrategia contraria, consistente en construir una cartera de coste cero que compra los títulos que peor se han comportado en el pasado (perdedores) y vende los que mejor lo han hecho (ganadores), no proporciona rentabilidades anormalmente positivas en el futuro cuando se analizan periodos de tres años, rechazándose por tanto la existencia de un efecto sobre-reacción en el mercado español y contradiciendo la evidencia previa obtenida en este mercado por Alonso y Rubio (1990). En este trabajo se aporta evidencia adicional sobre el comportamiento de la estrategia contraria mejorando varios aspectos. Por una parte se amplía a cuatro el número de estrategias contrarias analizadas dependiendo de cómo seleccionen los títulos ganadores y perdedores: periodos de formación de tres o cinco años y rentabilidad acumulada de forma aditiva o compuesta. Por otra parte se mejoran varios aspectos metodológicos: (i) las rentabilidades a largo plazo de las carteras son calculadas además de con el procedimiento aditivo con el de comprar-y-mantener, y (ii) se emplean metodologías que permiten trabajar con periodos de prueba solapados. Finalmente, se realiza un análisis estacional del comportamiento de la estrategia contraria diferenciando entre el mes de enero y el resto del año. Este estudio más exhaustivo de la estrategia contraria pone de manifiesto que la existencia de un efecto sobre-reacción en el mercado español no puede ser rechazada en principio para horizontes temporales de cinco años.sobre-reacción, rentabilidades a largo plazo, eficiencia, riesgo over-reaction, long-run returns, efficiency, risk

- ¿EXISTE EN EL MERCADO ESPAÑOL UN EFECTO SOBRE-REACCIÓN?.

Several studies have shown that the contrarian strategy, or the forming of a zeroinvestmentportfolio that buys the stocks that have performed poorly in the past (losers) andsells those that have performed well (winners), creates abnormally positive returns in thefuture. Many hypotheses have been suggested in an attempt to explain such strange behaviorby the market, but the most widely discussed is the so-called overreaction effect. In this paperwe analyze the contrarian strategy, in the empirical context of the Spanish stock market,using three-year periods, not only to form the portfolios of winners and losers, but also toanalyze the future performance of the stocks involved We follow the methodologies proposedby De Bondt and Thaler (1985) and Chan (1988), and we arrive at the conclusion that, withthe use of three-year periods, the contrarian strategy does not beat the market and, therefore,no overreaction effect is observed in the Spanish market. Numerosos estudios han puesto de manifiesto que la estrategia contraria, consistente enconstruir una cartera de arbitraje que compra los títulos que peor se han comportado en elpasado (perdedores) y vende los que mejor lo han hecho (ganadores), proporciona rentabilidadesanormalmente positivas en el futuro. Varias hipótesis se han barajado a la hora de explicar estecomportamiento anómalo del mercado; la más conocida, y también discutida, es el llamadoefecto sobre-reacción. En este trabajo analizamos la estrategia contraria en el mercadoespañol utilizando periodos de tres años, tanto para determinar la cartera de perdedores y deganadores como para analizar su comportamiento futuro. Para ello nos apoyamos en lametodología propuesta por De Bondt y Thaler (1985) y Chan (1988), llegando a la conclusión deque utilizando periodos de tres años la estrategia contraria no bate al mercado y, por lo tanto,no se observa sobre-reacción.eficiencia, sobre-reacción, riesgo, beta. Efficiency, Overreaction, Risk, Beta.

EL EFECTO MOMENTUM EN EL MERCADO ESPAÑOL DE ACCIONES

The momentum effect is perhaps one of the most embarrassing puzzles in the stock marketresearch nowadays. However, such phenomenon has received scarce attention in the Spanish Market.In this paper, we present a meticulous analysis of the momentum profits in this market, with specialconcern on its possible sources. Consistent with the evidence obtained in other markets, themomentum strategy yields important profits that can not be explained neither by the cross-sectiondispersion of the expected returns nor by a positive autocorrelation in the return generating factor/s.Such phenomenon seems to be driven by a positive autocorrelation in the specific return component,which seriously questions the market efficiency hypothesis. Moreover, the momentum effectevidenced in the Spanish market shows some peculiarities that make it different from the existing onein other countries. Specifically, it seems to disappear in the nineties and does not show any seasonalityin January. El efecto momentum es quizás uno de los enigmas más desconcertantes a los que se enfrenta hoy en día la investigación relativa al mercado de capitales. Sin embargo, dicho fenómeno ha acaparado escasa atención en el mercado español. En este trabajo se presenta un minucioso análisis de los beneficios del momentum en este mercado, realizando un especial hincapié en el estudio de las posibles fuentes que pueden estar ocasionándolo. Consistente con la evidencia obtenida en otros mercados, la estrategia de momentum proporciona importantes beneficios que no pueden ser explicados ni por la dispersión en la sección cruzada de las rentabilidades esperadas ni por una autocorrelación positiva en el/los factor/es que genera/n las rentabilidades. El origen de dicho fenómeno parece estar más bien en una autocorrelación positiva en el componente específico de las rentabilidades, lo cual cuestiona seriamente la hipótesis de eficiencia del mercado. Por otra parte, el efecto momentum detectado en este mercado presenta una serie de características que lo diferencian del existente en otros países, proporcionándole, en cierta medida, una entidad propia. Así, el momentum no parece persistir en la década de los noventa y tampoco presenta una estacionalidad negativa en el mes de enero.momentum, eficiencia del mercado, infra-reacción. momentum, market efficiency, infra-reaction.

Temperature changes in 2% chlorhexidine gluconate using two activation methods with different intensity levels

Chlorhexidine is an irrigant solution widely used in root canal treatment because of its good antimicrobial properties. However, its mixture with sodium hypochlorite results in the appearance of substance called p-chloroaniline, a cytotoxic substance. This is also found when chlorhexidine is heated. The use of passive ultrasonic irrigation is related to an irrigant thermal increase, which can cause the appearance of p-chloroaniline. Thus, the objective is to establish the influence of ultrasonic and sonic activation, with the use of different intensities, upon the temperature of chlorhexidine gluconate (CHX). The following groups were established: control (without activation), ultrasonic activation and sonic activation. A 0.5-ml volume of CHX was placed in an Eppendorf tube in a thermo-static bath at 37ºC. Both methods resulted in immediate CHX activation. The temperature was recorded every 30 seconds between 60 and 180 seconds. The statistical analysis was performed based on the Mann-Whitney U-test. Both groups subjected to activation showed higher temperatures than the control group, and increased activation intensity was associated to greater temperature increments in both activated groups. Both ultrasonic and sonic activation are correlated to temperature increase in CHX

Analysis of the human interaction with a wearable lower-limb exoskeleton

The design of a wearable robotic exoskeleton needs to consider the interaction, either physical or cognitive, between the human user and the robotic device. This paper presents a method to analyse the interaction between the human user and a unilateral, wearable lower-limb exoskeleton. The lower-limb exoskeleton function was to compensate for muscle weakness around the knee joint. It is shown that the cognitive interaction is bidirectional; on the one hand, the robot gathered information from the sensors in order to detect human actions, such as the gait phases, but the subjects also modified their gait patterns to obtain the desired responses from the exoskeleton. The results of the two-phase evaluation of learning with healthy subjects and experiments with a patient case are presented, regarding the analysis of the interaction, assessed in terms of kinematics, kinetics and/or muscle recruitment. Human-driven response of the exoskeleton after training revealed the improvements in the use of the device, while particular modifications of motion patterns were observed in healthy subjects. Also, endurance (mechanical) tests provided criteria to perform experiments with one post-polio patient. The results with the post-polio patient demonstrate the feasibility of providing gait compensation by means of the presented wearable exoskeleton, designed with a testing procedure that involves the human users to assess the human-robot interaction

Therapeutic exercise in fibromyalgia syndrome: a narrative review

Fibromyalgia syndrome (FMS) is characterised by the presence of distributed pain in different areas of the body accompanied by the alteration of some functions such as the activity of the neurovegetative system, the sleep quality, or the presence of fatigue. The present narrative review aims to evaluate some key studies regarding the effects of different therapeutic exercise (TE) modalities on clinical variables of interest in patients with FMS, as well as to discuss some of the possible mechanisms of action of TE in improving pain intensity in patients with FMS. All aerobic, strengthening, and body-mind exercises were shown to bring about changes in the improvement of clinical variables of interest in patients with FMS. In addition, with regard to the improvement of pain intensity, there are different arguments that could explain the hypoalgesic effect of TE (structured in physical, neurophysiological, and psychosocial mechanisms). In conclusion, TE is a clinical tool with great potential for patients with FMS as it may produce hypoalgesia through physical, neurophysiological, and psychosocial mechanisms. All these TE modalities have demonstrated in isolation a remarkable effectiveness in the overall improvement of patients with FMS. However, more research is needed in this field especially on the long-term effects and on the combination of the different training modalities

Characteristics of Encephalic Vascular Accident patients treated at a state reference center

Encephalic Vascular Accident is a clinical sign of brain dysfunction and it might result in permanent and irreversible lesions. Objective: Define the characteristics such as age, sex and date of the first treatment at a Santa Catarina State's Rehabilitation Center. Methods: This is a quantitative cross-sectional descriptive study. The Ethnics in Human Research (CEPSH), the Pro Rector for Research and Extension Federal University of Santa Catarina, number 1024 reviewed this study. Results: CVA affected 25,11% of women between 71-80 years old and 34,09% of the men aged between 61-70 years old. The most common consequence due to CVA was hemiplegia and the study observed that many patients only looked for proper treatment after several years post CVA. Conclusions: The physical therapy is important, so patients can relearn daily tasks and furthermore reintegrate their social life

Agronomic performance and remote sensing assessment of organic and mineral fertilization in rice fields

Introduction: Rice heavily relies on nitrogen fertilizers, posing environmental, resource, and geopolitical challenges. This study explores sustainable alternatives like animal manure and remote sensing for resource-efficient rice cultivation. It aims to assess the long-term impact of organic fertilization and remote sensing monitoring on agronomic traits, yield, and nutrition. Methods: A six-year experiment in rice fields evaluated fertilization strategies, including pig slurry (PS) and chicken manure (CM) with mineral fertilizers (MIN), MIN-only, and zero-fertilization. Traits, yield, spectral responses, and nutrient content were measured. Sentinel-2 remote sensing tracked crop development. Results: Cost-effective organic fertilizers (PS and CM) caused a 13% and 15% yield reduction but still doubled zero-fertilization yield. PS reduced nitrogen leaching. Heavy metals in rice grains were present at safe amounts. Organic-fertilized crops showed nitrogen deficiency at the late vegetative stages, affecting yield. Sentinel-2 detected nutrient deficiencies through NDVI. Discussion: Organic fertilizers, especially PS, reduce nitrogen loss, benefiting the environment. However, they come with yield trade-offs and nutrient management challenges that can be managed and balanced with reduced additional mineral applications. Sentinel-2 remote sensing helps manage nutrient deficiencies. In summary, this research favors cost-effective organic fertilizers with improved nutrient management for sustainable rice production.This work was commissioned and funded by the Catalan Ministry of Climate Action, Food and Rural Agenda, by the projects TED2021-131606B-C21 and PLEC2021-007786 of the Spanish Ministry of Economy and Competitiveness and by the CROPDIVA (Climate Resilient Orphan croPs for increased DIVersity in Agriculture) project through the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 101000847. The funders had no role in the study design, data collection and analysis, decision to publish, or manuscript preparation.info:eu-repo/semantics/publishedVersio