Equilibrium Nonexistence in Spatial Competition with Quadratic Transportation Costs

Under quadratic transportation costs, the existence of the sequential first-locate-thenprice equilibrium in spatial competition is well known in the literature. In this paper, we find that the equilibrium may fail to exist under certain restrictions with respect to the location of firms and consumers in the market. This result is valid for both the linear and the circular modelsProduct differentiation; circular model; linear model; quadratic transportation costs; sequential equilibrium

In The Game : An Exploration of the Concept of Immersion in Video-Games and its Usage in Game Design

This thesis outlines a research project whose aim was to develop a design taxonomy for the creation of immersion in video-games. These guidelines can then be used in-sync with different stages in video-game design and development to ensure an immersive experience. Integral to this is the \u27suspension of disbelief\u27 the end user experiences when fully immersed in a video-game (Holland, 2002; Mediacollage.com, 2006). A review of the literature has identified the major contributing theory to the concept of immersion as flow (Csikszentmihalyi, 1991). Flow embodies cognitive elements of involvement such as concentration on a task, completing a challenge, having control over the environment and so on. This cognitive flow is also integrated with affective components such as the loss of self consciousness and sense of \u27oneness\u27 with the environment. A model of immersion has been proposed that embraces the cognitive aspects of flow through the gameplay elements that have been integrated as well as the affective dimension of identification which can be achieved through the integration of narrative elements. Immersive gameplay is framed within the nature of the challenges the user faces. These vary, such as the psychomotor challenges inherent in platform games and shooters through cognitive challenges of quizzes and tutorials through to social challenges such as multiplayer online environments. The criteria for cognitive flow embrace but also extend on traditional theories of motivation. Concepts such as challenge and control (Astleitner & Weisner, 2004) combine with the relevance and confidence inherent in Keller\u27s ARCS theory of motivation (Rezabek, 1994) to describe the contingent aspects of gameplay. An understanding of these within the context of game goals, challenges, rules, boundaries and feedback can assist designers in applying appropriate criteria to ensure deep cognitive engagement on the part of the end user. Playing a game, however, is also an emotional and aesthetic experience. The term \u27emotioneering\u27 (Freeman, 2003) has been used to describe the ways in which designers create a sense of involvement with the game. These include traditional motivational constructs such as curiosity/attention, satisfaction and fantasy, and can be disaggregated to a range of criteria that may be used to guide the development of the affective aspects of gaming including player enacted narrative and role·play, the affective and the range of \u27interesting\u27 and \u27deepening\u27 techniques that can add emotional depth and complexity to the game world (Freeman, 2003) through visual and narrative design elements. The criteria developed from the immersion model are proposed as a lens to assist designers in understanding this state-of-mind. These criteria have been applied through the analysis of the use of existing games in a study on undergraduate students in game design and culture to ascertain their validity, and with the goal of providing guidelines for the future design of entertainment as well as serious games

Proving the Duffin-Schaeffer conjecture without GCD graphs

We present a novel proof of the Duffin-Schaeffer conjecture in metric Diophantine approximation. Our proof is heavily motivated by the ideas of Koukoulopoulos-Maynard's breakthrough first argument, but simplifies and strengthens several technical aspects. In particular, we avoid any direct handling of GCD graphs and their `quality'. We also consider the metric quantitative theory of Diophantine approximations, improving the $(\log \Psi(N))^{-C}$ error-term of Aistleitner-Borda and the first named author to $\exp(-(\log \Psi(N))^{\frac{1}{2} - \varepsilon})$

Osteoma osteoide sobre callo de fractura

Se comunica un caso de osteoma osteoide de localización tibial en un hombre de 23 años, cuya particularidad ha sido su manifestación clínica después de un largo intervalo libre y de haberse desarrollado sobre el lugar mismo del foco de una fractura cerrada tibial sucedida hacía 4 años. El diagnóstico se realizó por la clínica dolorosa de ritmo nocturno, por el estudio radiológico convencional, por tomografía axial computarizada (TAC) y Resonancia Nuclear Magnética (IRM). Su confirmación se hizo por estudio anatomopatológico. El tratamiento consistió en exéresis quirúrgica de la tumoración tras la cual desapareció el dolor no existiendo residuos después de un año. Aunque numerosas publicaciones han sido consagradas al osteoma osteoide, nos ha parecido interesante publicar esta observación particular de esta tumoración en razón de la rareza de su asiento sobre el lugar mismo del callo de una fractura.We report a case of osteoid osteoma in the tibial region in a 23 year old male, whose interest resides in its clinical appearance following a long period without pain and having developed in the same location of a closed tibial fracture that occured some 4 years ago. The diagnosis was performed in addition to the night-time pain experienced, by means of conventional Radiographic study, and Nuclear Magnetic Resonance Diagnostic. Its confirmation was carried out by pathological study. Treatment consisted in surgical exeresis of the tumour. Pain disappeared, after exeresis, not existing tumour ral tissue after one year follow-up. Although numerous publications have been made concerning the osteoide osteoma, it seems interesting to publish this particular case, because of the rarity of its occurrence in the same location of the callus of a fracture

Results of a major ambulatory oral surgery program using general inhalational anesthesia on disabled patients

Objectives: To assess the demographic characteristics and comorbidities of the group to be studied, as well as various quality indicators of a Major Ambulatory Surgery (MAS) program. Quantification of the surgical-anesthetic incidents. Study design: We aimed to perform a retrospective and descriptive analysis of disabled patients who had received oral ambulatory surgery under general anesthesia. Data obtained from the clinical history and telephone interview included the demographic characteristics, socioeconomic status, previous dental history, cause of the mental disability, degree of mental retardation, comorbidity measured according to the scale of the American Society of Anesthesiologists (ASA), anesthesia or preoperative surgical treatments, level of analgesia, length of stay, incidents in the Resuscitation Ward, the rate of substitution, suspensions, patients admitted, complications and the degree of patient satisfaction. Results: We included 112 oral surgery procedures performed on disabled patients who were treated under general inhalational anesthesia as part of MAS during the years 2006-2007. During this period, 577 restorations, 413 extractions, 179 sealants, 102 pulpectomies, 22 root canal treatments, 17 gingivectomies and 3 frenectomies were performed. A total of 75% (78 cases) of the patients had coexisting medical pathology. The average surgery time per patient was 72.69 ±29.78 minutes. The rate of replacement was 100%. The rate of suspension was 1.92%. The percentage of patients readmitted was 1.92%,due to significant bleeding in the mouth, which did not require treatment and the patients were discharged from hospital 24 hours after being admitted. The rate of patients who required re-hospitalization was 3.84%. Conclusions: The MAS performed in this group, despite being on patients with high comorbidity resulted in only a low number of medical incidents reporte