Perfect simulation for interacting point processes, loss networks and Ising models

We present a perfect simulation algorithm for measures that are absolutely continuous with respect to some Poisson process and can be obtained as invariant measures of birth-and-death processes. Examples include area- and perimeter-interacting point processes (with stochastic grains), invariant measures of loss networks, and the Ising contour and random cluster models. The algorithm does not involve couplings of the process with different initial conditions and it is not tied up to monotonicity requirements. Furthermore, it directly provides perfect samples of finite windows of the infinite-volume measure, subjected to time and space ``user-impatience bias''. The algorithm is based on a two-step procedure: (i) a perfect-simulation scheme for a (finite and random) relevant portion of a (space-time) marked Poisson processes (free birth-and-death process, free loss networks), and (ii) a ``cleaning'' algorithm that trims out this process according to the interaction rules of the target process. The first step involves the perfect generation of ``ancestors'' of a given object, that is of predecessors that may have an influence on the birth-rate under the target process. The second step, and hence the whole procedure, is feasible if these ``ancestors'' form a finite set with probability one. We present a sufficiency criteria for this condition, based on the absence of infinite clusters for an associated (backwards) oriented percolation model.Comment: Revised version after referee of SPA: 39 page

Loss network representation of Peierls contours

We present a probabilistic approach for the study of systems with exclusions, in the regime traditionally studied via cluster-expansion methods. In this paper we focus on its application for the gases of Peierls contours found in the study of the Ising model at low temperatures, but most of the results are general. We realize the equilibrium measure as the invariant measure of a loss-network process whose existence is ensured by a subcriticality condition of a dominant branching process. In this regime, the approach yields, besides existence and uniqueness of the measure, properties such as exponential space convergence and mixing, and a central limit theorem. The loss network converges exponentially fast to the equilibrium measure, without metastable traps. This convergence is faster at low temperatures, where it leads to the proof of an asymptotic Poisson distribution of contours. Our results on the mixing properties of the measure are comparable to those obtained with ``duplicated-variables expansion'', used to treat systems with disorder and coupled map lattices. It works in a larger region of validity than usual cluster-expansion formalisms, and it is not tied to the analyticity of the pressure. In fact, it does not lead to any kind of expansion for the latter, and the properties of the equilibrium measure are obtained without resorting to combinatorial or complex analysis techniques.Comment: 42 pages. Revised version after the first referee repor

Experiencias en la formación inicial de profesores de matemáticas

El sistema educativo nacional se hace explícito en el quehacer de sus profesores, pues son ellos quienes lo desarrollan, de ahí que sea preciso hacer investigación en torno a la profesionalización docente desde su formación inicial y continua. Este reporte comparte experiencias en la formación inicial del docente de matemáticas, en las cuáles se implementaron diseños de aprendizaje basado en elementos teórico-metodológicos de la socioepistemología y la investigación basada en diseños. Se trabajó con diseños de aprendizaje basados en modelación y covariación con estudiantes de licenciatura en matemáticas con perfil en matemática educativa con el objetivo de promover la reflexión sobre el quehacer docente y la identificación de elementos matemáticos y metodológicos esenciales en los diseños para lograr formular nuevas actividades matemáticas. Se recopilaron datos por medio de videos de clase y ensayos de los participantes sobre las actividades realizadas, esto dio luz sobre un posible modelo de desarrollo profesional docente

Los títeres y la argumentación matemática

En este reporte nos interesa discutir el papel que el títere juga en la argumentación matemática. El uso escolar del títere se refleja en varios reportes de investigación y libros que priorizan el desarrollo de la comunicación al establecer una interacción especial con muñecos, al estimular la imaginación de los niños, fomentar el juego creativo e introducir narrativa de modo interactivo, en temáticas generales. Bajo la mirada socioepistemológica y una metodología cualitativa, nos interesa poner el acento en el desarrollo de la argumentación matemática mediante obras que desafíen los saberes matemáticos de los participantes. Pretendemos ejemplificar, por medio de breves episodios, el diálogo que entablan los matetíteres al presentarse ante un público diverso a veces, y otras determinado, así como compartir un primer análisis de los recursos que se perciben en la interacción

Effect of green tea catechins in patients with high-grade prostatic intraepithelial neoplasia: Results of a short-term double-blind placebo controlled phase II clinical trial

Background and study objective: Several studies suggest a protective role of green tea catechins against prostate cancer (PCa). In order to evaluate the efficacy of green tea catechins for chemoprevention of PCa in patients with high-grade prostate intraepithelial neoplasia (HG-PIN) we performed a phase II clinical trial. Methods: Sixty volunteers with HG-PIN were enrolled to carry out a double-blind randomized placebo-controlled phase II clinical trial. Treated group took daily 600 mg of green tea catechins (Categ Plus®) for 1 year. Patients were screened at 6 and 12 months through prostatic biopsy and measurements of prostate-specific antigen (PSA). Results: Despite the statistically significant reduction of PSA observed in subjects who received green tea catechins for 6 and 12 months, we did not find any statistical difference in PCa incidence between the experimental groups neither after 6 nor after 12 months. However, throughout the one-year follow-up we observed very limited adverse effects induced by green tea catechins and a not significant improvement in lower urinary tract symptoms and quality of life. Conclusions: Although the small number of patients enrolled in our study and the relatively short duration of intervention, our findings seems to deny the efficacy of green tea catechins. However, results of our clinical study, mainly for its low statistical strength, suggest that the effectiveness of green tea catechins should be evaluated in both a larger cohort of men and longer trial

Una nueva especie de Catopsis (Bromeliaceae, Tillandsioideae, Catopsideae) de México

Catopsis occulta Mart.-Correa, Espejo & López-Ferr., a new endemic species from the states of Chiapas, Oaxaca and Veracruz in Mexico, is described and illustrated. The new taxon is characterized by dioecious, large plants with usually three times branched inflorescences and yellow-orange floral bracts and sepals. The new species is compared with C. berteroniana (Schult. & Schult. f.) Mez, which is morphologically similar.Se describe e ilustra Catopsis occulta Mart.-Correa, Espejo & López-Ferr., especie nueva endémica de los estados de Chiapas, Oaxaca y Veracruz en México. El nuevo taxon se caracteriza por sus plantas dioicas de gran tamaño con las inflorescencias generalmente tres veces ramificadas y las brácteas florales y los sépalos amarillo-anaranjados. Se le compara con C. berteroniana (Schult. & Schult. f.) Mez, la cual presenta características morfológicas similares

Agnoprotein of polyomavirus BK interacts with proliferating cell nuclear antigen and inhibits DNA replication

License:Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0)Background: The human polyomavirus BK expresses a 66 amino-acid peptide referred to as agnoprotein. Though mutants lacking agnoprotein are severely reduced in producing infectious virions, the exact function of this peptide remains incompletely understood. To elucidate the function of agnoprotein, we searched for novel cellular interaction partners. Methods: Yeast-two hybrid assay was performed with agnoprotein as bait against human kidney and thymus libraries. The interaction between agnoprotein and putative partners was further examined by GST pull down, co-immunoprecipitation, and fluorescence resonance energy transfer studies. Biochemical and biological studies were performed to examine the functional implication of the interaction of agnoprotein with cellular target proteins. Results: Proliferating cell nuclear antigen (PCNA), which acts as a processivity factor for DNA polymerase δ, was identified as an interaction partner. The interaction between agnoprotein and PCNA is direct and occurs also in human cells. Agnoprotein exerts an inhibitory effect on PCNA-dependent DNA synthesis in vitro and reduces cell proliferation when ectopically expressed. Overexpression of PCNA restores agnoprotein-mediated inhibition of cell proliferation. Conclusion: Our data suggest that PCNA is a genuine interaction partner of agnoprotein and the inhibitory effect on PCNA-dependent DNA synthesis by the agnoprotein may play a role in switching off (viral) DNA replication late in the viral replication cycle when assembly of replicated genomes and synthesized viral capsid proteins occurs

Getting Real Results with Ohio State University Extension’s Real Money. Real World. Program

Youth development organizations have a unique opportunity to offer programs that help young people develop financial skills they need to become successful adults. This article describes Ohio State University Extension’s Real Money. Real World. (RMRW) and the systematic approach used to evaluate its effectiveness. The RMRW curriculum includes an active, hands-on experience that gives young people the opportunity to make lifestyle and budget choices similar to those they will make as adults. The realistic simulation creates a teachable moment. The outcomes of the statewide evaluation clearly indicate the curriculum accomplishes its goals of raising awareness, changing attitudes, and motivating students to plan for behavior changes concerning financial management, education, and career choices. The article concludes with a discussion of the organizational outcomes of conducting the evaluation

Locating bomb factories by detecting hydrogen peroxide

The analytical capability to detect hydrogen peroxide vapour can play a key role in localizing a site where a H2O2 based Improvised Explosive (IE) is manufactured. In security activities it is very important to obtain information in a short time. For this reason, an analytical method to be used in security activity needs portable devices. The authors have developed the first analytical method based on a portable luminometer, specifically designed and validated to locate IE manufacturing sites using quantitative on-site vapour analysis for H2O2. The method was tested both indoor and outdoor. The results demonstrate that the detection of H2O2 vapours could allow police forces to locate the site, while terrorists are preparing an attack. The collected data are also very important in developing new sensors, able to give an early alarm if located at a proper distance from a site where an H2O2 based IE is prepared