Partial actions on quotient spaces and globalization

Given a partial action of a topological group $G$ on a space $X$, we determine properties $\mathcal P$ which can be extended from $X$ to its globalization. We treat the cases when $\mathcal P$ is any of the following: Hausdorff, regular, metrizable, second countable and having invariant metric. Further, for a normal subgroup $H$ we introduce and study a partial action of $G/H$ on the orbit space $X/\!\sim,$ applications to invariant metrics and inverse limits are presented.Comment: 14 page

Almost Fra\"iss\'e Banach spaces

Continuing with the study of Approximately ultrahomogeneous and Fra\"iss\'e Banach spaces introduced by V. Ferenczi, J. L\'opez-Abad, B. Mbombo and S. Todorcevic, we define formally weaker and in some aspects more natural properties of Banach spaces which we call Almost ultrahomogeneity and the Almost Fra\"iss\'e Property. We obtain relations between these different homogeneity properties of a space $E$ and relate them to certain pseudometrics on the class $\mathrm{Age}(E)$ of finite dimensional subspaces of $E$. We prove that ultrapowers of an almost Fra\"iss\'e Banach space are ultrahomogeneous. We also study two properties called finitely isometrically extensible and almost finitely isometrically extensible, respectively, and prove that approximately ultrahomogeneous Banach spaces are finitely isometrically extensible

Mathematical modeling with digital technological tools for interpretation of contextual situations

This article has the goal of proposing physical contextual situations modeling as a way to interpret mathematical representations that are produced by digital technological tools. Thus, there is an experimental situation-problem about a physical phenomenon that is modeled through video analysis and dynamic geometry software; the methodological model Cuvima conducts the experimental activity. Pre-testing and post-testing measuring instruments were designed to obtain the information and previous conceptions of ten graduate students in Mathematical Education, which showed a conceptual change. Similarly, results prove that digital technology, from a didactical sequence, supports and strengthens experimental work simplifying modeling processes of a physical phenomenon, promoting the use of mathematical representations to solve a situation-problem

CHARACTERIZATION OF THE VASCULAR PATHOLOGY IN THE ACTA2 R258C MOUSE MODEL AND CEREBROVASCULAR CHARACTERIZATION OF THE ACTA2 NULL MOUSE

Mutations in ACTA2, the gene encoding for smooth muscle α-actin, predispose patients to a wide range of vascular diseases and is most commonly associated with thoracic aortic aneurysms (TAAD) and dissections (TAAD) and strokes. TAAD in patients is characterized by aortic media degeneration and loss in contractile force generation followed by aortic enlargement and subsequent rupture. Most stroke cases associated with ACTA2 are described as moyamoya-like cerebrovascular incidents characterized by distal occlusion of the internal carotid artery, stenosis of arteries in the Circle of Willis, and straightening of cerebral arteries. Patient samples are scarcely available for analysis, and the few obtained are from end stages of the disease. For these reason, we decided to study the causative mechanisms of vascular disease using the Acta2R258C transgenic and Acta2-/- mouse models. The aortic phenotype was studied using the transgenic mouse model bred with Acta2-/- mice to decrease the ACTA2 wildtype to mutant ratio. Acta2+/+ R258C TGmice have decreased aortic contractility and mild medial wall degeneration but no evidence of aortic enlargement was observed. However, Acta2+/- R258C TG mice showed severe aortic wall degeneration, elastic fiber rupture and proteoglycan accumulation along with significant aortic dilation. After carotid artery ligation, Acta2+/- R258C TG mice presented with an excessive proliferative response to injury, leading to increased inflammatory response, unresolved thrombi and severe occlusion of the lumen. Cerebral imaging and histology were studied in WT, Acta2+/-, Acta-/- mouse mode. Straightening of the cerebrovascular arteries was observed in Acta2+/- and Acta2-/- mice when compared with WT mice. Narrowing and/or obstruction of arteries were also present in the Acta2 mutant mice, in particular in the internal carotid arteries. Histopathologic analysis showed thickening of the medial layer in both large and small arteries throughout the vasculature with decreased cell density in the large arteries. We were able to recapitulate significant characteristics of the aortic and cerebrovascular pathology seen in patients with ACTA2 mutations in our Acta2 mouse models, proving to be a valuable tool to study the underlying mechanisms of vascular disease. Furthermore, both aneurysm formation and SMC proliferative response were exacerbated by decreasing the amount of endogenous Acta2 in our transgenic model. The severity of the cerebrovascular pathology did not vary between Acta2+/- and Acta-/-, suggesting a dose dependent effect in these mice. Meanwhile, the Acta2 R258C mutation appears to have a dominant negative effect, as its effects are inversely correlated to the amount of endogenous actin in an organism

Continuos g-contraíbles

Diremos que un continuo X es g-contraíble si existe una función continua y sobre yectivaf: X→X que es homotópica a una función constante. En este artículo hacemos una recopilación de los resultados conocidos acerca de los continuos g-contraíbles. Mostraremos que existe un continuo que no es g-contraíble tal que el producto numerable de él con sí mismo sí lo es. Con esto damos respuesta negativa a un caso particular de la Pregunta 3.2 que propusimos en el artículo “Ong-contractibility of continua”.    A continuum X is said to be g-contractible provided that there is a surjective map f: X→X which is homotopic to a constant map. In this article, we will study g-contractible continua. Answering a particular case ofa proposed question in the article“On g-contractibility of continua” [3], we will show that there exists a non-g-contractible continuum X such that its countable product X Nis g-contractible

Continuos g-contraíbles

Diremos que un continuo X es g-contraíble si existe una función continua y sobre yectivaf: X→X que es homotópica a una función constante. En este artículo hacemos una recopilación de los resultados conocidos acerca de los continuos g-contraíbles. Mostraremos que existe un continuo que no es g-contraíble tal que el producto numerable de él con sí mismo sí lo es. Con esto damos respuesta negativa a un caso particular de la Pregunta 3.2 que propusimos en el artículo “Ong-contractibility of continua”.  

Altitude and COVID-19 in Colombia : an updated analysis accounting for potential confounders

Q4Q2Pacientes con COVID-19We assessed the relationship between the altitude of municipalities and the incidence, mortality, and fatality from COVID-19 and excess of mortality in Colombia between 2020 and 2022. We conducted an ecologic study including all 1122 municipalities in Colombia and used categories of altitude as main independent variable. We fit multivariable regression models for incidence, mortality, fatality rates, and excess of mortality controlling for several variables at municipality level. There was a higher incidence rate, similar mortality rate and lower case-fatality rate for COVID-19 during 2020–2022 in municipalities in the upper category of altitude (>=2500 masl) compared to the lower category (<1000 masl). The excess of mortality was lower but not statistically different in municipalities in the upper category of altitude, and significantly lower in the intermediate altitude category compared to the lowlands. Our findings provide evidence that municipalities with high altitude had similar mortality rate, and lower case-fatality rate and excess of mortality for COVID-19 compared to lowlands in Colombia.https://orcid.org/0000-0002-0100-1940Revista Internacional - IndexadaA2N

Epidemia por COVID-19 en Colombia: del “pico” de la emergencia a la sostenibilidad de la respuesta

El pasado 6 de marzo de 2020 se identificó el primer caso de infección por SARS-Cov-2 en Colombia. Luego de seis meses de desarrollo de la epidemia, la mayoría de las ciudades del país han experimentado un periodo agudo de ascenso de casos y fallecimientos, así como las consecuencias devastadoras sobre sus economías. En el ambiente nacional y regional se percibe un agotamiento gubernamental y ciudadano por la afectación de la epidemia en términos de la cantidad de infectados y fallecidos y por el tiempo transcurrido con las medidas de aislamiento preventivo obligatorio que se prolongaron desde el 25 de marzo hasta el 1 de septiembre en todo el territorio nacional. Sin embargo, estamos todavía lejos de estar cerca del final de la epidemia y en esta nueva etapa se requiere pasar del centralismo de la respuesta inicial a la sostenibilidad de la respuesta regional.El pasado 6 de marzo de 2020 se identificó el primer caso de infección por SARS-Cov-2 en Colombia. Luego de seis meses de desarrollo de la epidemia, la mayoría de las ciudades del país han experimentado un periodo agudo de ascenso de casos y fallecimientos, así como las consecuencias devastadoras sobre sus economías. En el ambiente nacional y regional se percibe un agotamiento gubernamental y ciudadano por la afectación de la epidemia en términos de la cantidad de infectados y fallecidos y por el tiempo transcurrido con las medidas de aislamiento preventivo obligatorio que se prolongaron desde el 25 de marzo hasta el 1 de septiembre en todo el territorio nacional. Sin embargo, estamos todavía lejos de estar cerca del final de la epidemia y en esta nueva etapa se requiere pasar del centralismo de la respuesta inicial a la sostenibilidad de la respuesta regional.On March 6, 2020, the first case of SARS-Cov-2 infection was identified in Colombia. After six months of development of the epidemic in Colombia, most cities in the country have experienced an acute period of rise in cases and deaths as well as the devastating consequences on their economies. In the national and regional environment, government and citizen exhaustion is perceived due to the impact of the epidemic in terms of the number of infected and deceased and the time elapsed with the mandatory preventive isolation measures that lasted from March 25 to September 1 throughout the national territory. However, we are still far from being close to the end of the epidemic and in this new stage it is necessary to move from the centrality of the initial response to the sustainability of the regional response