Matching couples with Scarf’s algorithm

Scarf's algorithm [20] provides fractional core elements for NTU-games. Bir�o and Fleiner [3] showed that Scarf's algorithm can be extended for capacitated NTU-games. In this setting agents can be involved in more than one coalition at a time, cooperations may be performed with di�erent intensities up to some limits, and the contribution of the agents can also di�er in a coalition. The fractional stable solutions for the above model, produced by the extended Scarf algorithm, are called stable allocations. In this paper we apply this solution concept for the Hospitals / Residents problem with Couples (HRC). This is one of the most important general stable matching problems due to its relevant applications, also well-known to be NP-hard. We show that if a stable allocation yielded by the Scarf algorithm turns out to be integral then it provides a stable matching for an instance of HRC, so this method can be used as a heuristic. In an experimental study, we compare this method with other heuristics constructed for HRC that are applied in practice in the American and Scottish resident allocation programs, respectively. Our main �nding is that the Scarf algorithm outperforms all the other known heuristics when the proportion of couples is high

‘How does your health system work?’: a workshop at the WONCA Europe Conference 2012….

Last week around 2000 general practitioners (GPs) met in Vienna to discuss the theme of The Art and Science of General Practice at the annual WONCA Europe Conference (4-7 July). Yet one of the most conversation-starting topics on the agenda could be argued was neither directly art, nor purely clinical science. Over 200 GPs from around the world participated in a workshop on health systems financing, and were intrigued to learn more about the methods used to collect, pool and spend funds in health systems. The audience ranged from medical students to senior members of the profession, and highlighted broad differences in the levels of understanding of how health systems function. Some questioned why it was the first time in their careers that they had been given the opportunity to get an overview of the theory behind the core principles of health systems financing

The visible environment of galaxies with counterrotation

In this paper we present a statistical study of the environments of 49 galaxies in which there is gas- or stellar- counterrotation. The number of possible companions in the field (to apparent magnitude 22), their size and concentration were considered. All the statistical parameters were analysed by means of Kolgomorov-Smirnov tests, using a control sample of 43 galaxies without counterrotation. From our data, no significant differences between the counter-rotating and control samples appear. This is different to Seyfert or radio-loud galaxies which lie in environments with a higher density of companions. On the contrary, if a weak tendency exists, for galaxies with gas counterrotation only, it is discovered in regions of space where the large scale density of galaxies is smaller. Our results tend to disprove the hypothesis that counterrotation and polar rings derive from a recent interaction with a small satellite or a galaxy of similar size. To a first approximation, they seem to follow the idea that all galaxies are born through a merger process of smaller objects occurring very early in their life, or that they derive from a continuous, non-traumatic infall of gas that formed stars later. Whatever the special machinery is which produces counterrotation or polar rings instead of a co-planar, co-rotating distribution of gas and stars, it seems not to be connected to the present galaxy density of their environments.Comment: 9 pages, 1 figure, accepted for publication in A&

BMQ

BMQ: Boston Medical Quarterly was published from 1950-1966 by the Boston University School of Medicine and the Massachusetts Memorial Hospitals. Pages 49-52, v17n2, provided courtesy of Howard Gotlieb Archival Research Center

Uso de viruta de madera y lirio acuático (eichhornia crassipes) como agentes estructurantes en tratamientos aerobios de residuos hortícolas.

En procesos aerobios para tratar residuos orgánicos con alto contenido de humedad y bajo contenido de lignina y celulosa, deben emplearse agentes estructurantes para favorecer la aireación y por lo tanto el buen desarrollo del bioproceso. En este trabajo se utilizó una mezcla de viruta de madera y lirio acuático seco (Eichhornia crassipes) como agente estructurante en diferentes porcentajes (5, 10, 15 y 20 %). Cada tratamiento fue hecho por triplicado y estuvo compuesto de una mezcla que contenía los seis bioresiduos generados en mayor cantidad en la Central de Abasto de la Ciudad de México. Los experimentos se llevaron a cabo en celdas de material acrílico donde se colocó una mezcla de 1200 g de residuos y material estructurante. Durante el proceso, los parámetros medidos fueron el pH, la temperatura, la densidad, el contenido de humedad, la generación de lixiviados y la reducción de masa. Los resultados mostraron que el elevado contenido de humedad de la mezcla puede ser regulado con materiales estructurantes secos, ya que estos materiales absorben parte del lixiviado durante las primeras semanas del proceso y mejoran la textura de las pilas evitando con esto que la degradación se lleve a cabo en condiciones de anaerobiosis. Tomando como base la generación de lixiviados y la reducción de masa, los mejores resultados se obtuvieron usando un 15 % de agente estructurante, el cual estaba compuesto de una mezcla de 6:1 viruta de madera y lirio acuático.In aerobic treatments for solid waste with high humidity content and low lignine and cellulose, bulking agents must be applied in order to improve the aeration and the performance of the process. In the present work, a mixture of wood shaving and dry water lily (Eichhornia crassipes) was tested as bulking agent at different percentages (5, 10, 15 and 20 %). Each assay was prepared by triplicate and was composed by a mixture of the six most important horticultural waste from a big market (Central de Abasto de la Ciudad de Mexico). The assays were run in acrylic cells where 1200 g of organic waste and bulking agent were mixed. During the process, pH, temperature, density, humidity content, leachate generation and mass reduction were measured. Results showed that the high rate of humidity of this mixture could be regulated by adding dry materials. These agents absorb some leachate during the first weeks of the process and the texture in the windrow was improved avoiding the anaerobic biodegradation of this kind of waste. Evaluating the leachates generation and the mass reduction, the best results have been obtained using 15 % of bulking agent, which it was composed by 6:1 wood shavings and dry water lily.Los autores agradecen al Consejo Nacional de Ciencia y Tecnología (CONACYT) y al Instituto Politécnico Nacional (IPN) por el financiamiento de este proyecto y a la COFAA-IPN por el apoyo para la divulgación de los resultados de este trabajo

Persona y modelo: Un llamado al profesor universitario

¿Alguna vez te has preguntado qué significa realmente ser una "persona"? Más allá de definiciones abstractas y filosóficas, la noción de persona se entrelaza con nuestra capacidad de actuar, amar y tomar decisiones morales. Desde la perspectiva de pensadores como Boecio y Tomás de Aquino, la persona no solo es un ser racional, sino un ente que, a través del amor y la libertad, se forja su propio camino en el mundo

A General Factor of Personality in 16 sets of the Big Five, the Guilford-Zimmerman Temperament Survey, the California Psychological Inventory, and the Temperament and Character Inventory

In four studies, we tested the hypothesis that a General Factor of Personality (GFP) occupies the apex of the hierarchy. In Study 1, a GFP was found in 16 sets of Big Five inter-scale correlations (N = 6412) which explained 54% of the variance in the two first-order factors. In Study 2, a GFP was found in validation samples from the Guilford-Zimmerman Temperament Survey (N = 2917) which explained 36% of the variance in three first-order factors and 21% of the total reliable variance in a model that went from 10 primary traits to 3 higher-order traits to the GFP. In Study 3, a GFP was found in a validation sample of the California Psychological Inventory (N = 6000) which explained 35% of the variance in two second-order factors, 17% of the variance in six first-order factors, and 20% of the total reliable variance in 20 primary traits. In Study 4, a GFP was found in two validation samples of the Temperament and Character Inventory (N = 1285) which explained 49% of the variance in three first-order factors and 24% of the total reliable variance in a model that went from 7 primary traits to 3 higher-order traits to the GFP. © 2009 Elsevier Ltd. All rights reserved