Information theoretic refinement criteria for image synthesis

Aquest treball està enmarcat en el context de gràfics per computador partint de la intersecció de tres camps: rendering, teoria de la informació, i complexitat.Inicialment, el concepte de complexitat d'una escena es analitzat considerant tres perspectives des d'un punt de vista de la visibilitat geomètrica: complexitat en un punt interior, complexitat d'una animació, i complexitat d'una regió. L'enfoc principal d'aquesta tesi és l'exploració i desenvolupament de nous criteris de refinament pel problema de la il·luminació global. Mesures de la teoria de la informació basades en la entropia de Shannon i en la entropia generalitzada de Harvda-Charvát-Tsallis, conjuntament amb les f-divergències, són analitzades com a nuclis del refinement. Mostrem com ens aporten una rica varietat d'eficients i altament discriminatòries mesures que són aplicables al rendering en els seus enfocs de pixel-driven (ray-tracing) i object-space (radiositat jeràrquica).Primerament, basat en la entropia de Shannon, es defineixen un conjunt de mesures de qualitat i contrast del pixel. S'apliquen al supersampling en ray-tracing com a criteris de refinement, obtenint un algorisme nou de sampleig adaptatiu basat en entropia, amb un alt rati de qualitat versus cost. En segon lloc, basat en la entropia generalitzada de Harvda-Charvát-Tsallis, i en la informació mutua generalitzada, es defineixen tres nous criteris de refinament per la radiositat jeràrquica. En correspondencia amb tres enfocs clàssics, es presenten els oracles basats en la informació transportada, el suavitzat de la informació, i la informació mutua, amb resultats molt significatius per aquest darrer. Finalment, tres membres de la familia de les f-divergències de Csiszár's (divergències de Kullback-Leibler, chi-square, and Hellinger) son analitzats com a criteris de refinament mostrant bons resultats tant pel ray-tracing com per la radiositat jeràrquica.This work is framed within the context of computer graphics starting out from the intersection of three fields: rendering, information theory, and complexity.Initially, the concept of scene complexity is analysed considering three perspectives from a geometric visibility point of view: complexity at an interior point, complexity of an animation, and complexity of a region. The main focus of this dissertation is the exploration and development of new refinement criteria for the global illumination problem. Information-theoretic measures based on Shannon entropy and Harvda-Charvát-Tsallis generalised entropy, together with f-divergences, are analysed as kernels of refinement. We show how they give us a rich variety of efficient and highly discriminative measures which are applicable to rendering in its pixel-driven (ray-tracing) and object-space (hierarchical radiosity) approaches.Firstly, based on Shannon entropy, a set of pixel quality and pixel contrast measures are defined. They are applied to supersampling in ray-tracing as refinement criteria, obtaining a new entropy-based adaptive sampling algorithm with a high rate quality versus cost. Secondly, based on Harvda-Charvát-Tsallis generalised entropy, and generalised mutual information, three new refinement criteria are defined for hierarchical radiosity. In correspondence with three classic approaches, oracles based on transported information, information smoothness, and mutual information are presented, with very significant results for the latter. And finally, three members of the family of Csiszár's f-divergences (Kullback-Leibler, chi-square, and Hellinger divergences) are analysed as refinement criteria showing good results for both ray-tracing and hierarchical radiosity

Quatre dècades de la Unitat de Bioestadística de la Facultat de Medicina de la Universitat de Barcelona: descripció i canvis docents

Podeu consultar la Vuitena trobada de professorat de Ciències de la Salut completa a: http://hdl.handle.net/2445/66524Introducció: La Bioestadística es va introduir a la Facultat de Medicina (FM) de la Universitat de Barcelona (UB) en el curs acadèmic 1973-74 en el nou pla d’estudis que aleshores començava. D’aleshores fins l’actualitat s’han produït diferents canvis en la docència d’aquesta disciplina científica. Objectius: Descriure i avaluar els canvis docents en les 4 dècades de la introducció de la Bioestadística en els plans d’estudis del ensenyament de Medicina, i mes específicament en la FM de la UB. Cal indicar que aquesta presentació forma part d’un projecte mes ampli d’avaluació de l’impacte de la docència de la Bioestadística en l’àmbit mèdic. Material i Mètodes: Dades secundaries recollides de diferents fonts d’ informació relacionades amb la FM de la UB des de 1973 fins l’actualitat pel que fa referencia a l’estructura i recursos de la docència. S’han emprat mètodes descriptius per valorar les 4 dècades docents de la Bioestadística en la FM de la UB. Principals resultats: L’any 1973 va ser molt important per la vida acadèmica de l’estat espanyol: hi va haver-hi un canvi de normativa que volia fer coincidí els anys acadèmics amb els anys naturals (“Calendari Juliano”). El curs acadèmic..

Association of depression phenotypes and antidepressant treatment with mortality due to cancer and other causes: a community-based cohort study

Fàrmac antidepressiu; Càncer; Síndrome depressiuFármaco antidepresivo; Cáncer; Síndrome depresivoAntidepressant drug; Cancer; Depressive syndromeObjective: This study aimed to assess the association of somatic depressive symptoms (SDS), cognitive/emotional depressive symptoms (C-EDS), and antidepressant treatment on mortality due to cancer and other causes in a community cohort.Methods: A community-based sample recruited in 1995, 2000, and 2005 aged between 35 and 75 years was examined in two waves and followed for a median of 6.7 years. SDS and C-EDS phenotypes were assessed using the Patient Health Questionnaire-9. Medication used by participants was collected. Deaths and their causes were registered during follow-up. Cox proportional hazard models stratified by sex were performed to determine the association between depressive phenotypes and mortality.Results: The cohort consisted of 5,646 individuals (53.9% women) with a mean age of 64 years (SD = 11.89). During the follow-up, 392 deaths were recorded, of which 27.8% were due to cancer. C-EDS phenotype was associated with an increased risk of cancer mortality in both men (HR = 2.23; 95% CI = 1.11–4.44) and women (HR = 3.69; 95% CI = 1.69–8.09), and SDS was significantly associated with non-cancer mortality in men (HR = 2.16; 95 CI % = 1.46–3.18). Selective serotonin reuptake inhibitors (SSRIs) were significantly associated with both cancer (HR = 2.78; 95% CI = 1.10–6.98) and non-cancer mortality (HR = 2.94; 95% CI = 1.76–4.90) only in the male population.Conclusion: C-EDS phenotype was related to an increased risk of cancer mortality at 6 years. In addition, the use of SSRIs in the male population was associated with cancer and all-cause mortality.Objectiu: aquest estudi pretenia avaluar l'associació de símptomes depressius somàtics (SDS), símptomes depressius cognitius/emocionals (C-EDS) i tractament antidepressiu sobre la mortalitat per càncer i altres causes en una cohort comunitària. Mètodes: una mostra basada en la comunitat reclutada el 1995, 2000 i 2005 d'entre 35 i 75 anys es va examinar en dues onades i es va seguir durant una mitjana de 6,7 anys. Els fenotips SDS i C-EDS es van avaluar mitjançant el Patient Health Questionnaire-9. Es van recollir els medicaments utilitzats pels participants. Durant el seguiment es van registrar les morts i les seves causes. Es van realitzar models de risc proporcional de Cox estratificats per sexe per determinar l'associació entre fenotips depressius i mortalitat. Resultats: La cohort estava formada per 5.646 individus (53,9% dones) amb una edat mitjana de 64 anys (DE = 11,89). Durant el seguiment es van registrar 392 defuncions, de les quals el 27,8% van ser per càncer. El fenotip C-EDS es va associar amb un augment del risc de mortalitat per càncer tant en homes (HR = 2,23; IC 95% = 1,11-4,44) com en dones (HR = 3,69; IC 95% = 1,69-8,09), i el SDS es va associar significativament. amb mortalitat no per càncer en homes (HR = 2,16; IC 95 % = 1,46–3,18). Els inhibidors selectius de la recaptació de serotonina (ISRS) es van associar significativament tant amb el càncer (HR = 2,78; IC 95% = 1,10-6,98) com amb la mortalitat no per càncer (HR = 2,94; IC 95% = 1,76-4,90) només a la població masculina. Conclusió: el fenotip C-EDS es va relacionar amb un augment del risc de mortalitat per càncer als 6 anys. A més, l'ús d'ISRS a la població masculina es va associar amb càncer i mortalitat per totes les causes.This study was supported by the research grant STL006/17/00234 from the Strategic Plan for Health Research and Innovation (PERIS) 2016–2020 of the Department of Health, Government of Catalonia. The funding sources played no role in the design and conduct of the study, collection, management, analysis, and interpretation of the data, nor in the preparation, review, or approval of the manuscript

Ecosystem services provided by green infrastructure in the urban environment

Interest in ecosystems services and green infrastructures is a result of conceptual developments in urban ecology and other environmental sciences. The impact of the urban settlements on nature and its consequences on human well-being at multi-scale levels demands for technical and social responses, whose application has been revealed to be highly dependent on the physical and socio-economic context. We review here problems and efforts to create a solid conceptual framework and efficient tools to analyse and manage urban social-ecosystems in order to increase the benefits that green infrastructure gives to the entire society, giving resilience to these systems. Difficulties become even greater as a result of weak institutional structures, limited capacity and poor governance strategies

Gender analysis of the frequency and course of depressive disorders and relationship with personality traits in general population: a prospective cohort study

Depressió; Epidemiologia; PersonalitatDepresión; Epidemiología; PersonalidadDepression; Epidemiology; PersonalityBackground: We aimed to determine the prevalence and course of subthreshold depressive symptomatology (sDS) and probable major depressive episode (MDE) and to examine their association with personality traits among men and women. Methods: A community-based sample aged 35 years or older was examined in two waves (median follow-up of 6.9 years). The Patient Health Questionnaire-9 (PHQ-9) was used to assess sDS and MDE. The 10-item version of the Big Five Inventory was used to assess personality traits. Prevalence was assessed at baseline (n=5,557) and incidence and persistence-recurrence rates were computed at follow up (n=3,102). Logistic regression models were adjusted to explore the association of personality traits with prevalence and course of depressive disorders. Results: The prevalence of sDS and MDE was 14.04% (95% CI = 17.04-19.08) and 8.54 (95% CI=7.82-9.31), the incidence was 14.30 per 1,000 person-years (95% CI=12.49-16.31) and 4.34 per 1,000 person-years (95% CI=3.46-5.36), and the persistence-recurrence was 35.04 per 1,000 person-years (95% CI=29.00-41.96) and 28.8 per 1,000 person-years (95% CI=20.49-38.14). The gender gap was higher for MDE. Personality traits were differentially associated with the prevalence and course of depressive disorders between men and women. Limitations: Because this study used questionnaires to assess depressive disorders and personality traits, information bias could not be ruled out. Conclusions: The gender gap was higher for the prevalence and course of the probable MDE. There were more personality traits related with the course of the sDS and they had a major role in the course of the probable MDE in women.This study was supported by research grant STL006/17/00234 from the Strategic Plan for Health Research and Innovation (PERIS) 2016-2020 of the Department of Health. Government of Catalunya

Added value of intraoperative real-time imaging in searches for difficult-to-locate sentinel nodes.

Localization of sentinel lymph nodes can be challenging if they are in difficult anatomic locations or near high radiotracer activity The purpose of this study was to assess the value of intraoperative real-time imaging using a portable gamma-camera in conjunction with a conventional gamma-counting probe when it is difficult to localize the sentinel node