Multi-stage oligopoly models with nested logit demand structures: A simplifying approach

Solving multi-stage oligopoly models by backward induction can easily become a com- plex task when rms are multi-product and demands are derived from a nested logit frame- work. This paper shows that under the assumption that within-segment rm shares are equal across segments, the analytical expression for equilibrium pro ts can be substantially simpli ed. The size of the error arising when this condition does not hold perfectly is also computed. Through numerical examples, it is shown that the error is rather small in general. Therefore, using this assumption allows to gain analytical tractability in a class of models that has been used to approach relevant policy questions, such as for example rm entry in an industry or the relation between competition and location. The simplifying approach proposed in this paper is aimed at helping improving these type of models for reaching more accurate recommendations.

Appropriateness of methadone maintenance treatment for opiate addiction: evaluation by an expert panel.

With some 30,000 dependent persons, opiate addiction constitutes a major public health problem in Switzerland. The Swiss Federal Office of Public Health (FOPH) has long played a leading role in the prevention and treatment of opiate addiction and in research on effective means of containing the epidemic of opiate addiction and its consequences. Major milestones on that path have been the successive "Methadone reports" published by that Office and providing guidance on the care of opiate addiction with substitution treatment. In view of updating the recommendations for the appropriateness of substitution treatment for opiate addiction, in particular for the prescription of methadone, the FOPH commissioned a multi-component project involving the following elements. A survey of current attitudes and practices in Switzerland related to opiate substitution treatment Review of Swiss literature on methadone substitution treatment Review of international literature on methadone substitution treatment National Methadone Substitution Conference Multidisciplinary expert panel to evaluate the appropriateness of substitution treatment. The present report documents the process and summarises the results of the latter element above. The RAND appropriateness method (RAM) was used to distil from literature-based evidence and systematically formulated expert opinion, areas where consensus exist on the appropriateness (or inappropriateness) of methadone maintenance treatment (MMT) and areas where disagreement or uncertainty persist and which should be further pursued. The major areas which were addressed by this report are Initial assessment of candidates for MMT Appropriate settings for initiation of MMT (general and special cases) Appropriateness of methadone supportive therapy Co-treatments and accompanying measures Dosage schedules and pharmacokinetic testing Withdrawal from MMT Miscellaneous questions Appropriateness of other (non-methadone) substitution treatment Summary statements for each of the above categories are derived from the panel meeting and presented in the report. In the "first round", agreement was observed for 31% of the 553 theoretical scenarios evaluated. The "second round" rating, following discussion of divergent ratings, resulted in a much higher agreement among panellists, reaching 53% of the 537 scenarios. Frank disagreement was encountered for 7% of all scenarios. Overall 49% of the clinical situations (scenarios) presented were considered appropriate. The areas where at least 50% of the situations were considered appropriate were "initial assessment of candidates for MMT", the "appropriate settings for initiation of MMT", the "appropriate settings for methadone supportive treatment" and "Appropriateness of other (non-methadone) substitution treatment". The area where there was the least consensus on appropriateness concerned "appropriateness of withdrawal from MMT" (6%). The report discusses the implications and limitations of the panel results and provides recommendations for the dissemination, application, and future use of the criteria for the appropriateness of MMT. The RAND Appropriateness Method proved to be an accepted and appreciated method to assess the appropriateness of methadone maintenance treatment for opiate addicts. In the next step, the results of the expert panel process must now be combined with those of the Swiss and international literature reviews and the survey of current attitudes and practices in Switzerland, to be synthesized into formal practice guidelines. Such guidelines should be disseminated to all concerned, promoted, used and rigorously evaluated for compliance and outcome.

Profitability, uncertainty and multi-product firm product proliferation: The Spanish car industry

This article studies how product introduction decisions relate to profitability and uncertainty in the context of multi-product firms and product differentiation. These two features, common to many modern industries, have not received much attention in the literature as compared to the classical problem of firm entry, even if the determinants of firm and product entry are quite different. The theoretical predictions about the sign of the impact of uncertainty on product entry are not conclusive. Therefore, an econometric model relating firms’ product introduction decisions with profitability and profit uncertainty is proposed. Firm’s estimated profits are obtained from a structural model of product demand and supply, and uncertainty is proxied by profits’ variance. The empirical analysis is carried out using data on the Spanish car industry for the period 1990-2000. The results show a positive relationship between product introduction and profitability, and a negative one with respect to profit variability. Interestingly, the degree of uncertainty appears to be a driving force of entry stronger than profitability, suggesting that the product proliferation process in the Spanish car market may have been mainly a consequence of lower uncertainty rather than the result of having a more profitable market. Keywords: Product introduction, entry, uncertainty, multiproduct firms, automobile JEL codes: L11, L13

Tensor products of Leavitt path algebras

Vegeu el resum a l'inici del document del fitxer adjunt.

Construcción de un modelo Multi- Regional Input-Output (MRIO) medioambiental para Cataluña y el resto de España: Estudio del balance en CO2 incorporado en el comercio

El objetivo de este estudio es analizar el impacto, en emisiones de CO2, de la demanda final de Cataluña en relación a los vínculos comerciales interregionales con el resto de España y el resto del mundo. Este proceso implica el análisis del balance en CO2 incorporado para Cataluña, lo que permitirá evaluar la responsabilidad de la economía catalana respecto a estas emisiones. Para este propósito se construye, para esta determinada desagregación regional, un modelo Multi-Regional Input-Output (MRIO) extendido al medioambiente con sectores verticalmente integrados. La incorporación de la técnica de la integración vertical nos permite un enfoque alternativo para el Balance Neto y un análisis más detallado de los vínculos interregionales entre los diversos sectores productivos, centrado en la responsabilidad última de la demanda final de cada sector en cada región. Hasta el momento, los estudios previos sobre los impactos medioambientales incorporados al comercio español se han centrado principalmente en el ámbito nacional. No obstante, por un lado el comercio interregional con el resto de España en términos monetarios representa cerca de la mitad del comercio exterior catalán. Por otro lado, los distintos metabolismos energéticos de ambas economías tienen como consecuencia una importante diferencia en la intensidad de emisión en la producción de bienes y servicios. Esta situación genera para Cataluña un déficit en el Balance Neto estimado con el resto de España, aún teniendo un importante superávit monetario. De esto se desprende la importancia de integrar el nivel interregional en los estudios de los impactos medioambientales incorporados en el comercio y, en consecuencia, en la planificación y formalización de políticas económicas y ambientales a nivel nacional.

Protective immunity of single and multi-antigen DNA vaccines against schistosomiasis

We evaluated the usefulness of the combination of three plasmids encoding tegumental (pECL and pSM14) and muscular (pIRV5) antigens of the Schistosoma mansoni on improving the protective immunity over the use of a single antigen as DNA vaccines. Female BALB/c mice were inoculated twice with 25 µg DNA plasmid within two weeks interval. The challenge was performed with 80 cercarias of a regional isolate of S. mansoni (SLM) one week after the last immunization. Six weeks after challenge, all mice were perfused for worm load determination. The following groups were analyzed: saline; empty vector; monovalent formulations of pECL; pSM14 and pIRV5 and also double combinations of pECL/pIRV5 and pIRV5/pSM14 and a triple combination of pECL/pIRV5/pSM14. The protection was expressed as a percentage of worm loads in each group compared with the saline group. The results obtained were 41% (p < 0.05); 52% (p < 0.05); 51% (p < 0.05); 48% (p < 0.05); 55% (p < 0.05); 45% (p < 0.05); 65% (p < 0.05) for each group respectively.

Optimització d'una aplicacio bioinformàtica d'alineament de seqüències executada en processadors multi-core i many-core (GPUs)

Las aplicaciones de alineamiento de secuencias son una herramienta importante para la comunidad científica. Estas aplicaciones bioinformáticas son usadas en muchos campos distintos como pueden ser la medicina, la biología, la farmacología, la genética, etc. A día de hoy los algoritmos de alineamiento de secuencias tienen una complejidad elevada y cada día tienen que manejar un volumen de datos más grande. Por esta razón se deben buscar alternativas para que estas aplicaciones sean capaces de manejar el aumento de tamaño que los bancos de secuencias están sufriendo día a día. En este proyecto se estudian y se investigan mejoras en este tipo de aplicaciones como puede ser el uso de sistemas paralelos que pueden mejorar el rendimiento notablemente.

A multi-perspective approach to performance anxiety in music students

AbstractPerforming publicly has become increasingly important in a variety of professions. This condition is associated with performance anxiety in almost all performers. Whereas some performers successfully cope with this anxiety, for others it represents a major problem and even threatens their career. Musicians and especially music students were shown to be particularly affected by performance anxiety.Therefore, the goal of this PhD thesis was to gain a better understanding of performance anxiety in university music students. More precisely, the first part of this thesis aimed at increasing knowledge on the occurrence, the experience, and the management of performance anxiety (Article 1). The second part aimed at investigating the hypothesis that there is an underlying hyperventilation problem in musicians with a high level of anxiety before a performance. This hypothesis was addressed in two ways: firstly, by investigating the association between the negative affective dimension of music performance anxiety (MPA) and self-perceived physiological symptoms that are known to co-occur with hyperventilation (Article 2) and secondly, by analyzing this association on the physiological level before a private (audience-free) and a public performance (Article 3). Article 4 places some key variables of Article 3 in a larger context by jointly analyzing the phases before, during, and after performing.The main results of the self-report data show (a) that stage fright is experienced as a problem by one-third of the surveyed students, (b) that the students express a considerable need for more help to better cope with it, and (c) that there is a positive association between negative feelings of MPA and the self-reported hyperventilation complaints before performing. This latter finding was confirmed on the physiological level in a tendency of particularly high performance-anxious musicians to hyperventilate. Furthermore, the psycho-physiological activation increased from a private to a public performance, and was higher during the performances than before or after them. The physiological activation was mainly independent of the MPA score. Finally, there was a low response coherence between the actual physiological activation and the self-reports on the instantaneous anxiety, tension, and perceived physiological activation.Given the high proportion of music students who consider stage fright as a problem and given the need for more help to better cope with it, a better understanding of this phenomenon and its inclusion in the educational process is fundamental to prevent future occupational problems. On the physiological level, breathing exercises might be a good means to decrease - but also to increase - the arousal associated with a public performance in order to meet an optimal level of arousal needed for a good performance.

Evolution of ascariasis in humans and pigs: a multi-disciplinary approach

The nematode parasite Ascaris lumbricoides infects the digestive tracts of over 1.4 billion people worldwide, and its sister species, Ascaris suum, has infected a countless number of domesticated and feral pigs. It is generally thought that the putative ancestor to these worms infected either humans or pigs, but with the advent of domestication, they had ample opportunity to jump to a new host and subsequently specialize and evolve into a new species. While nuclear DNA markers decisively separate the two populations, mitochondrial sequences reveal that three major haplotypes are found in A. suum and in A. lumbricoides, indicating either occasional hybridization, causing introgression of gene trees, or retention of polymorphism dating back to the original ancestral species. This article provides an illustration of the combined contribution of parasitology, archaeoparasitology, genetics and paleogenetics to the history of ascariasis. We specifically investigate the molecular history of ascariasis in humans by sequencing DNA from the eggs of Ascaris found among ancient archeological remains. The findings of this paleogenetic survey will explain whether the three mitochondrial haplotypes result from recent hybridization and introgression, due to intensive human-pig interaction, or whether their co-occurrence predates pig husbandry, perhaps dating back to the common ancestor. We hope to show how human-pig interaction has shaped the recent evolutionary history of this disease, perhaps revealing the identity of the ancestral host.

Application of control measures for infections caused by multi-resistant gram-negative bacteria in intensive care unit patients

Multi-resistant gram-negative rods are important pathogens in intensive care units (ICU), cause high rates of mortality, and need infection control measures to avoid spread to another patients. This study was undertaken prospectively with all of the patients hospitalized at ICU, Anesthesiology of the Hospital São Paulo, using the ICU component of the National Nosocomial Infection Surveillance System (NNIS) methodology, between March 1, 1997 and June 30, 1998. Hospital infections occurring during the first three months after the establishment of prevention and control measures (3/1/97 to 5/31/97) were compared to those of the last three months (3/1/98 to 5/31/98). In this period, 933 NNIS patients were studied, with 139 during the first period and 211 in the second period. The overall rates of infection by multi-resistant microorganisms in the first and second periods were, respectively, urinary tract infection: 3.28/1000 patients/day; 2.5/1000 patients/day; pneumonia: 2.10/1000 patients/day; 5.0/1000 patients/day; bloodstream infection: 1.09/1000 patients/day; 2.5/1000 patients/day. A comparison between overall infection rates of both periods (Wilcoxon test) showed no statistical significance (p = 0.067). The use of intervention measures effectively decreased the hospital bloodstream infection rate (p < 0.001), which shows that control measures in ICU can contribute to preventing hospital infections.

Criteria for establishing shielding of multi-detector computed tomography (MDCT) rooms.

The aim of this work is to compare two methods used for determining the proper shielding of computed tomography (CT) rooms while considering recent technological advances in CT scanners. The approaches of the German Institute for Standardisation and the US National Council on Radiation Protection and Measurements were compared and a series of radiation measurements were performed in several CT rooms at the Lausanne University Hospital. The following three-step procedure is proposed for assuring sufficient shielding of rooms hosting new CT units with spiral mode acquisition and various X-ray beam collimation widths: (1) calculate the ambient equivalent dose for a representative average weekly dose length product at the position where shielding is required; (2) from the maximum permissible weekly dose at the location of interest, calculate the transmission factor F that must be taken to ensure proper shielding and (3) convert the transmission factor into a thickness of lead shielding. A similar approach could be adopted to use when designing shielding for fluoroscopy rooms, where the basic quantity would be the dose area product instead of the load of current (milliampere-minute).