A Behavioral Foundation for Models of Evolutionary Drift

Binmore and Samuelson (1999) have shown that perturbations (drift) are crucial to study the stability properties of Nash equilibria. We contribute to this literature by providing a behavioural foundation for models of evolutionary drift. In particular, this article introduces a microeconomic model of drift based on the similarity theory developed by Tversky (1977), Kahneman and Tversky (1979) and Rubinstein (1988),(1998). An innovation with respect to those works is that we deal with similarity relations that are derived from the perception that each agent has about how well he is playing the game. In addition, the similarity relations are adapted to a dynamic setting. We obtain different models of drift depending on how we model the agent´s assessment of his behaviour in the game. The examples of the ultimatum game and the chain-store game are used to show the conditions for each model to stabilize elements in the component of Nash equilibria that are not subgame- perfect. It is also shown how some models approximate the laboratory data about those games while others match the data.

Irakurle konpetenteak lortze aldera

[EUS] Irakurriaren ulermenaren eremu ezin zabalagora hurbiltzeko hainbat arlo ukituko ditugu artikulu honetan. Lehenik eta behin, gai honen gaineko garraztasunak arintzeko Wiki bat diseinatu dugu eta bertan hainbat atal ikuskatuko ditugu. Wiki hau, Lehen Hezkuntzako nahiz DBHko hainbat irakasleekin landu da, beti ere, irakurriaren ulermena eskolan zertan hobetu daitekeen ikusteko. Beraz, artikuluarekin batera wikiaren jarraipena egitea gomendatzen da. Hona hemen helbidea: www.letutaletu.wikispaces.com . Artikulu honek lau atal aski diferente izango ditu. Atal hauen helbururik behiena, Lehen Hezkuntzako hirugarren zikloko nahiz DBHko lehenengo zikloko irakasleei zein ikasleei irakurriaren ulermenaren gaineko hainbat lanabes praktiko ematea litzateke. Horretarako, lehen atalean, eskolak irakurriaren ulermenaren gainean diagnosia egin dezan hainbat gogoeta ekarpen gisara planteatuko dira. Bigarrenik, irakasleek klaseetan irakurketa estrategiak lan ditzaten lan eskema bat proposatuko da. Hirugarrenik, azalpen testuek dituzten zailtasunen inguruan hausnartuko da eta zailtasun horiek gainditze aldera irakasleari hainbat erreminta emango zaizkio. Eta azkenik, bibliografiak edota irakurketak errazteko hainbat ekarpen egingo dira.

Intervenciones grupales en mujeres con cáncer de mama para mejorar su calidad de vida

[Es]El propósito de este trabajo es realizar una revisión sistemática de las intervenciones de grupo llevadas a cabo con mujeres con cáncer de mama y comprobar en qué medida mejoran la calidad de vida de estas pacientes. Actualmente, debido a la creciente incidencia de este tipo de neoplasia, es preciso evaluar las intervenciones de las que se disponen para lograr un tratamiento efectivo, eficaz y eficiente. Para ello, la revisión se realizó empleando las bases de datos más relevantes, como PubMed, Scielo, Fundación Index y Cochrane Library, de manera que se seleccionaron 14 de los 24 artículos encontrados, rechazando 10 por no cumplir los objetivos del presente trabajo. Los resultados hallados mostraron que las intervenciones que se utilizaron para mejorar los factores psicológicos y sociales, fueron las más utilizadas, logrando mejorar el estado psicosocial de las pacientes. El resto de intervenciones grupales encontradas en esta revisión se empleó para reducir el dolor de las participantes, logrando disminuirlo y controlarlo. Para realizar estas valoraciones, los autores de los estudios analizados emplearon cuestionarios y escalas como el EORTC QLQ-C30, el EORTC QLQ-BR23, el HADS, el POMS, el STAI y la escala EVA. Finalmente se puede concluir que a pesar de la ayuda que estas intervenciones grupales suponen en la mejora de la calidad de vida para la paciente con cáncer de mama, estas no aumentan su supervivencia.

Feedback on the Rate and Depth of Chest Compressions during Cardiopulmonary Resuscitation Using Only Accelerometers

Background Quality of cardiopulmonary resuscitation (CPR) is key to increase survival from cardiac arrest. Providing chest compressions with adequate rate and depth is difficult even for well-trained rescuers. The use of real-time feedback devices is intended to contribute to enhance chest compression quality. These devices are typically based on the double integration of the acceleration to obtain the chest displacement during compressions. The integration process is inherently unstable and leads to important errors unless boundary conditions are applied for each compression cycle. Commercial solutions use additional reference signals to establish these conditions, requiring additional sensors. Our aim was to study the accuracy of three methods based solely on the acceleration signal to provide feedback on the compression rate and depth. Materials and Methods We simulated a CPR scenario with several volunteers grouped in couples providing chest compressions on a resuscitation manikin. Different target rates (80, 100, 120, and 140 compressions per minute) and a target depth of at least 50 mm were indicated. The manikin was equipped with a displacement sensor. The accelerometer was placed between the rescuer's hands and the manikin's chest. We designed three alternatives to direct integration based on different principles (linear filtering, analysis of velocity, and spectral analysis of acceleration). We evaluated their accuracy by comparing the estimated depth and rate with the values obtained from the reference displacement sensor. Results The median (IQR) percent error was 5.9% (2.8-10.3), 6.3% (2.9-11.3), and 2.5% (1.2-4.4) for depth and 1.7% (0.0-2.3), 0.0% (0.0-2.0), and 0.9% (0.4-1.6) for rate, respectively. Depth accuracy depended on the target rate (p < 0.001) and on the rescuer couple (p < 0.001) within each method. Conclusions Accurate feedback on chest compression depth and rate during CPR is possible using exclusively the chest acceleration signal. The algorithm based on spectral analysis showed the best performance. Despite these encouraging results, further research should be conducted to asses the performance of these algorithms with clinical data.