Exit times in non-Markovian drifting continuous-time random walk processes

By appealing to renewal theory we determine the equations that the mean exit time of a continuous-time random walk with drift satisfies both when the present coincides with a jump instant or when it does not. Particular attention is paid to the corrections ensuing from the non-Markovian nature of the process. We show that when drift and jumps have the same sign the relevant integral equations can be solved in closed form. The case when holding times have the classical Erlang distribution is considered in detail.Comment: 9 pages, 3 color plots, two-column revtex 4; new Appendix and references adde

About the Dirac Equation with a δ\delta potential

An elementary treatment of the Dirac Equation in the presence of a three-dimensional spherically symmetric $\delta (r-r_0)$-potential is presented. We show how to handle the matching conditions in the configuration space, and discuss the occurrence of supercritical effects.Comment: 8 pages, 1 postscript figure, Latex, Revise

Rumen fermentative activity in the goat and sheep

No Abstract

Three types of shopping precincts. Three different ways to influence the public sphere of neighborhoods

Indexación: Scopus.Considerando que en la teoría urbana el mercado y los espacios públicos están históricamente vinculados, este artículo analiza un mercado, una galería comercial y un centro comercial (mall). El fin es ilustrar los factores que son determinantes para que en Santiago de Chile estas tipologías de comercio adquieran carácter público y puedan contribuir a la esfera pública de la ciudad, al menos dentro de las limitaciones que se derivan de su condición privada. Hasta ahora el debate ha reflexionado extensivamente sobre estas tres tipologías, sin embargo, existen aún pocos estudios que miran la vida pública que tiene lugar en estas diferentes tipologías de manera paralela, considerando que hoy todas ellas están presentes simultáneamente en la ciudad y se disputan su espacio en ella. Esta investigación describe características físicoespaciales y de administración de estos tres casos para aportar a las políticas públicas y el diseño urbano. Se estudia el comercio en relación a la accesibilidad a nivel metropolitano y en cuanto a los diferentes tipos de comercio, que pretenden atraer un público diverso y promueven el carácter público de los espacios.According to urban theory, commerce and public spaces are historically related to each other. Based on this premise, this paper analyzes a market, a shopping center and a mall. The goal of this research is to identify the key factors that turn these shopping precincts into public spaces and contribute to the public sphere in Santiago, Chile, at least within the context of the limitations associated with their private nature. To date, these three typologies have been the focus of intense debate. However, there are few studies of the public life that takes place in these spaces, especially when considering that they coexist simultaneously in the city, claiming a space within it. This research describes the physical-spatial and administrative characteristics of these three cases in order to contribute to the strengthening of public policies in urban design. Likewise, commerce is studied in relation to accessibility patterns at metropolitan level and the types of markets that aim to attract different users and promote the public nature of these spaces.https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-83582018000100089&lng=en&nrm=iso&tlng=e

Climate change impact on thermal comfort in Mexico City housing

This is the author accepted manuscript. The final version is available from WEENTECH via the DOI in this record4th International Conference on Energy, Environment and Economics (ICEEE2019), 20-22 August 2019, Edinburgh, ScotlandA two storey terraced house was modelled in ESP-r with a simple window opening control strategy to represent typical dwellings found in Mexico City and the adjoining municipalities. Future weather data was generated for years in this century based on morphing methods developed from the literature and by the authors and a TMY weather file developed from historical data between 1975 to 1989 by WhiteBox Technologies. The population in the region under consideration is a little over 20 million which represents 16% of Mexico’s population. The present day climate is such that air conditioning is rarely used in single family housing. The main cooling strategy in the hottest months (Mid February to mid June) is window opening. This was modelled considering that if the interior temperature was at or above 18°C and the exterior air temperature was below the interior air temperature then windows would be open. The air flow was modelled using the flow network model within ESP-r. It was found that in the latter part of the present century, this strategy would become increasingly ineffective. This is likely to lead to a considerable increase in installed air conditioning in single family dwellings and a consequent increase in electricity demand and consumption leading to a need for substantial investments in electricity transmission and distribution systems in the region to bring in power from distant sources.Engineering and Physical Sciences Research Council (EPSRC)CONACYT-SENER-Sustentabilidad Energética fund Mexic

Conocimiento y actitud del odontólogo frente al manejo del tabaquismo: estudio comparativo entre España, Italia y Venezuela

espanolIntroduccion: El Odontologo es capaz de ejercer un gran impacto en el tabaquismo a traves de su contacto con los pacientes y la deteccion precoz de lesiones bucales. El objetivo de este estudio fue determinar el conocimiento y la actitud de los odontologos frente al tabaquismo en tres paises distintos. Materiales y metodos: Se realizo una encuesta a 293 odontologos, 93 de ellos localizados en Caracas (OV), 90 con practica odontologica en Madrid (OE) y 110 en Milan (OI). Resultados: 46 OE y 22 OI indicaron ser fumadores, mientras que tan solo 10 OV admitieron ser fumadores. 80 (86,02%) OV, 66 (73,33%) OE y todos los OI refirieron registrar en la historia datos relacionados con tabaquismo en la primera consulta del paciente. La mayoria motiva a sus pacientes a dejar de fumar, sin embargo, 72,04% (67) OV, 55,55% (50) OE y 100% OI no recomiendan ninguna terapia de apoyo. Solo 7 odontologos (2,38%) (2 OV y 5 OE) reconocieron el medicamento Bupropion pero ningun odontologo lo ha indicado. Finalmente, 137 odontologos han diagnosticado cancer bucal, de los cuales 108 eran OI. Conclusiones: Los odontologos, independientemente del pais, tienen actitudes positivas para participar en el control del tabaquismo, pero no manejan la informacion relacionada ni ejercen un rol activo en la cesacion. Probablemente esta situacion se deba a la falta de entrenamiento durante sus estudios de pre y/o postgrado lo cual amerita una revision de los planes curriculares de Odontologia a nivel mundial. EnglishIntroduction: Health care professionals have an important role in tobacco control. Dentists are capable of having a great impact in smoking cessation due to their regular contact with patients and the rapid detection of oral signs produced by smoking. Unfortunately, there are few dentists actively involved in smoking control. The aim of this study was to investigate various aspects of dentists' beliefs and practices with respect to smoking cessation. Materials & Methods: A questionnaire about smoking cessation was filled in person by 293 dentists. 93 dentists were from Caracas-Venezuela (VD), 90 were from Madrid-Spain (SD) and 110 from Milan-Italy (ID). Results: 46 SD and 22 ID were smokers. Only 10 VD admitted to smoke. 80 (86.02%) VD, 66 (73.33%) SD and 100% of ID said that they recorded smoking status during the first consultation. However, none routinely update their records on smoking status. The majority of respondents encourage their patients to stop smoking, though, 72.04% (67) VD, 55.55% (50) SD and 100% ID do not recommend or prescribe any cessation therapy. Just 7 (2.38%) of all dentists had heard about the use of Bupropion, however, they had never indicated. Finally, 137 dentists (108 ID) have diagnosed oral cancer in their patients. Conclusions: Dentists have positive attitudes to being involved in smoking cessation interventions, but they do not manage all the information related to it. It is probably due to a lack of training or education during their undergraduate and postgraduate studies. Further studies should evaluate inclusion of smoking cessation instruction in Venezuelan, Spanish and Italian dentistry curriculum

The influence of climatic conditions on the transmission dynamics of the 2009 A/H1N1 influenza pandemic in Chile

BACKGROUND: The role of demographic factors, climatic conditions, school cycles, and connectivity patterns in shaping the spatio-temporal dynamics of pandemic influenza is not clearly understood. Here we analyzed the spatial, age and temporal evolution of the 2009 A/H1N1 influenza pandemic in Chile, a southern hemisphere country covering a long and narrow strip comprising latitudes 17°S to 56°S. METHODS: We analyzed the dissemination patterns of the 2009 A/H1N1 pandemic across 15 regions of Chile based on daily hospitalizations for severe acute respiratory disease and laboratory confirmed A/H1N1 influenza infection from 01-May to 31-December, 2009. We explored the association between timing of pandemic onset and peak pandemic activity and several geographical and demographic indicators, school vacations, climatic factors, and international passengers. We also estimated the reproduction number (R) based on the growth rate of the exponential pandemic phase by date of symptoms onset, estimated using maximum likelihood methods. RESULTS: While earlier pandemic onset was associated with larger population size, there was no association with connectivity, demographic, school or climatic factors. In contrast, there was a latitudinal gradient in peak pandemic timing, representing a 16-39-day lag in disease activity from the southern regions relative to the northernmost region (P < 0.001). Geographical differences in latitude of Chilean regions, maximum temperature and specific humidity explained 68.5% of the variability in peak timing (P = 0.01). In addition, there was a decreasing gradient in reproduction number from south to north Chile (P < 0.0001). The regional mean R estimates were 1.6-2.0, 1.3-1.5, and 1.2-1.3 for southern, central and northern regions, respectively, which were not affected by the winter vacation period. CONCLUSIONS: There was a lag in the period of most intense 2009 pandemic influenza activity following a South to North traveling pattern across regions of Chile, significantly associated with geographical differences in minimum temperature and specific humidity. The latitudinal gradient in timing of pandemic activity was accompanied by a gradient in reproduction number (P < 0.0001). Intensified surveillance strategies in colder and drier southern regions could lead to earlier detection of pandemic influenza viruses and improved control outcomes

A study of self-concept among Mexican-American/Chicano(a) students attending community colleges and four-year institutions of higher education in Oregon

The purpose of this research was to do a comparative study of the self-concept of Mexican-American/Chicano(a) students enrolled in two- and four-year institutions of higher education in western Oregon during the 1985-1986 academic year. The secondary purposes of the research were: 1) To ascertain if there were any significant differences in self-concept of the two-year community college students versus the four-year institution students. 2) To collect demographic data from the participants and to establish a demographic profile. The study respondents were drawn from all the minority students with Spanish surnames enrolled in the four institution studied: 33 community college students and 68 four-year institution of higher education students. The Tennessee Self Concept Scale (TSCS) and a demographic and personal background questionnaire were used. Hypotheses Ia IIa. IIIa, and IVa were analyzed using analysis of variance in a Split-Plot design method. A one-way classification analysis of variance to test the relationship of "the total positive" with the set of questions was used. The findings on the four hypotheses and on the relationship between the "total positive" with a set of questions from the demographic and personal background questionnaire revealed that there was no significant difference in the self-concept of either group of two-and four-year institutions of higher education students in any category that was tested (sex, age level, etc.). The relationship between the "total positive" from the TSCS with a set of questions from the demographic and personal background questionnaire also indicated no significant differences except in regard to year in school (seniors had a higher self-concept than juniors, juniors than sophomores, and sophomores than freshmen) and in regard to "student's view on academic achievement." The students who indicated "above-average" on "view of academic achievement" had higher mean scores on the "total positive" score (TSCS) than the ones who indicated "average" or "below-average." The conclusion can be drawn from this research that self-concept does not affect choice of post-secondary educational institution. In general, all Mexican-American/Chicano(a) students in this research have a similar view of themselves. However, when level of education is taken into consideration, the upper-division students have higher "total positive" scores than the lowerdivision students. Furthermore, this research has also identified some general characteristics of the Mexican-American/Chicano(a) students attending the two- and four-year institutions of higher education in western Oregon

SAVASA project @ TRECVID 2012: interactive surveillance event detection

In this paper we describe our participation in the interactive surveillance event detection task at TRECVid 2012. The system we developed was comprised of individual classifiers brought together behind a simple video search interface that enabled users to select relevant segments based on down~sampled animated gifs. Two types of user -- `experts' and `end users' -- performed the evaluations. Due to time constraints we focussed on three events -- ObjectPut, PersonRuns and Pointing -- and two of the five available cameras (1 and 3). Results from the interactive runs as well as discussion of the performance of the underlying retrospective classifiers are presented