The Islamic Crossed-Arch Domes in Cordoba: Geometry and Structural Analysis of the “Capilla de Villaviciosa”

Crossed-arch domes are a singular type of ribbed vaults. Their characteristic feature is that the ribs that form the vault are intertwined, forming polygons or stars, leaving an empty space in the centre. The earliest known vaults of this type are found in the Great Mosque of Córdoba, built ca. 960 a.C. The type spread through Spain, and the north of Africa in the 10th to the 16th Centuries, and was used by Guarini and Vittone in the 17th and 18th Centuries in Italy. However, it was used only in a few buildings. Though the literature about the structural behaviour of ribbed Gothic vaults is extensive, so far no structural analysis of crossed arch domes has been made. The purpose of this work is, first to show the way to attack such an analysis within the frame of Modern Limit Analysis of Masonry Structures (Heyman 1995), and then to apply the approach to study the stability of the dome of the Capilla de Villaviciosa. The work may give some clues to art and architectural historians to understand better the origin and development of Islamic dome architecture

POLICY IMPLICATIONS OF TRANSFERRING PATIENTS TO PRIVATE PRACTICE

We construct a model to analyze the willingness of Health Authorities to reach agreements with private hospitals to have some of their public sector patients treated there. When physicians are dual suppliers, we show that a problem of cream-skimming arises and reduces the incentives of the government to undertake such a policy. We argue that the more disperse the severities of the patients are, the greater the reduction in the incentives will be. Moreover, we characterize the distortion that the cream-skimming phenomenon imposes on the characteristics of the policy, when this is implemented.Regulation; Physician's Incentives; Public-Private Health Services; Patient Selection.

The Gatekeeping Role of General Practitioners. Does Patients' Information Matter?

We develop a principal-agent model in which the health authority acts as a principal for both a patient and a general practitioner (GP). The goal of the paper is to investigate the relative merits of gatekeeping and non-gatekeeping systems and to analyze the role of the quality of patient information and referral pressure in determining which model dominates. We find that, whenever GPs incentives matter, non-gatekeeping is better only if there is a sufficiently high pressure for referral. At the same time, for a non-gatekeeping system to dominate, the quality of the patient information should not be extreme: neither too bad (patient’ s self-referral would be very inefficient) nor too good (the GP’s agency problem would be very costly).General Practice, Moral hazard, Incentives, Patients’ beliefs, Patients’ pressure, Referrals.

New perspectives in the design of pharmaceutical copayments

In this paper we propose a new approach for the design of pharmaceutical copayments. We departure from the standard efficiency argument that advocates for copayments that are decreasing in the health benefits of the patients in order to discipline consumption. Under our approach, copayments are justified by the difficulties for the provider to fully fund their health services.pharmaceutical copayments, equity, axiomatic bargaining, claims

A Theoretical Approach to Dual Practice Regulations in the Health Sector

Internationally, there is wide cross-country heterogeneity in government responses to dual practice in the health sector. This paper provides a uniform theoretical framework to analyze and compare some of the most common regulations. We focus on three interventions: banning dual practice, offering rewarding contracts to public physicians, and limiting dual practice (including both limits to private earnings of dual providers and limits to involvement in private activities). An ancillary objective of the paper is to investigate whether regulations that are optimal for developed countries are adequate for developing countries as well. Our results offer theoretical support for the desirability of different regulations in different economic environments.Dual practice, optimal contracts, physicians' incentives, regulations.

OPTIMAL SHARING OF SURGICAL COSTS IN THE PRESENCE OF QUEUES

We deal with a cost allocation problem arising from sharing a medical service in the presence of queues. We use a standard queuing theory model in a context with several medical procedures, a certain demand of treatment and a maximum average waiting time guarantee set by the government. We show that sharing the use of an operating theatre to treat the patients of the different procedures, leads to a cost reduction. Then, we compute an optimal fee per procedure for the use of the operating theatre, based on the Shapley value. Afterwards, considering the post-operative time, we characterize the conditions under which this cooperation among treatments has a positive impact on the average post-operative costs. Finally, we provide a numerical example constructed on the basis of real data, to highlight the main features of our model.Surgical Waiting Lists; Queueing Theory; Cost-Sharing Game.

Who do physicians work for?

This paper presents a thorough analysis of the issue of dual job holding among physicians. As the causes and implications of this phenomenon may well depend on the specific form of dual practice under consideration, we first introduce a typology of dual practice in the health sector based on the public versus private nature of the activity and the work regime involved. Our primary focus is on public on private practice, since it is more prevalent and poses greater adverse welfare effects than do other forms. We commence our analysis with a review of the theoretical and empirical economic literature on public on private dual job holding among physicians in developing and developed countries and analyze its underlying motives and economic effects. We find that economic motives are not the only reason why physicians engage in dual practice. Other non-pecuniary factors such as job complementarities, and institutional, professional, structural and personal variables play a relevant role and, hence, should also be taken into account when regulating dual practice. Furthermore, while dual providers may be tempted to skimp on time and effort in their main job, to induce demand for their private services, or to misuse public resources, the legalization of dual practice may also contribute to recruit and retain physicians with less strain on the budget and improve access to health services, especially in developing countries. Finally, the paper highlights the lack of evidence regarding the extent and effects of this phenomenon. Given its implications for the equity, efficiency and quality of health care provision, dual practice among physicians warrants more attention from researchers and policy makers alike.Dual jobs, health sector, public-private, typology of dual practice.

Trials, Tricks and Transparency: How Disclosure Rules Affect Clinical Knowledge

Scandals of selective reporting of clinical trial results by pharmaceutical firms have underlined the need for more transparency in clinical trials. We provide a theoretical framework which reproduces incentives for selective reporting and yields three key implications concerning regulation. First, a compulsory clinical trial registry complemented through a voluntary clinical trial results database can implement full transparency (the existence of all trials as well as their results is known). Second, full transparency comes at a price. It has a deterrence effect on the incentives to conduct clinical trials, as it reduces the firms' gains from trials. Third, in principle, a voluntary clinical trial results database without a compulsory registry is a superior regulatory tool; but we provide some qualified support for additional compulsory registries when medical decision-makers cannot anticipate correctly the drug companies' decisions whether to conduct trials.pharmaceutical firms, strategic information transmission, clinical trials, registries, results databases, scientific knowledge.

Repetibilidad de la fotorrefracción en población universitaria sana

Introducción. La ambliopía provoca una disminución de la visión sin causa patológica que, si se trata a tiempo, puede llegar a ser reversible. La importancia de la detección de la ambliopía reside en la posterior calidad visual del paciente con un desarrollo visual normal. En la actualidad, existen diferentes instrumentos que realizan screening visual con el fin de proporcionar una buena visión. Por lo tanto, el objetivo de este trabajo es analizar la repetibilidad de un fotorrefractómetro PlusOptiX® A12C (Núremberg, Alemania), comparándolo con otros métodos como son autorrefractómetro RC-1000 (Tomey, Japón), refracción objetiva con retinoscopio Beta 200® (Heine, Alemania) y refracción subjetiva, tomado como gold standard, para garantizar su fiabilidad. Material y método. Se realizaron tres medidas consecutivas de cada parámetro con el autorrefractómetro RC-1000 (Tomey, Japón) y el PlusOptiX® A12C (Núremberg, Alemania) a los 67 sujetos que aceptaron participar en el estudio. Se obtuvieron valores de esfera, cilindro, eje, distancias interpupilares, diámetros pupilares y asimetría de mirada. Para fijar la validez de estos métodos de medida se analizó la desviación intrasesión (Sw), la precisión intrasesión (P), la repetibilidad, el coeficiente de variación (CV) y el coeficiente de correlación intraclase (CCI). Resultados. Se obtuvo en un 95,52% de los casos una medida analizable. El fotorrefractómetro PlusOptiX® A12C muestra mejor repetibilidad que el autorrefractómetro RC-1000, además de no mostrar diferencias estadísticamente significativas con el autorrefractómetro (P=0,38 para esfera, P=0,25 para cilindro y P=0,07 para eje). Sin embargo, en comparación con refracción subjetiva y retinoscopia muestra diferencias estadísticamente significativas (P<0,01 para esfera y cilindro y P=0,01 para eje y P<0,01 para esfera, cilindro y eje respectivamente), por lo que estos valores no podrían emplearse para su prescripción. Además, la repetibilidad de la fotorrefracción para la esfera, cilindro y eje muestra valores de Sw de 0,15, 0,09 y 19,37; CV de 15,41%, 14,98% y 20,44%; CCI de 0,997, 0,984 y 0,884 respectivamente. Conclusiones. La repetibilidad obtenida con PlusOptiX® A12C muestra que es mejor método que el autorrefractómetro RC-1000 por proporcionar valores más repetibles que este, pero la refracción obtenida difiere significativamente del gold standard.Grado en Óptica y Optometrí