On closure operators and reflections in Goursat categories

By defining a closure operator on effective equivalence relations in a regular category $C$, it is possible to establish a bijective correspondence between these closure operators and the regular epireflective subcategories $L$ of $C$. When $C$ is an exact Goursat category this correspondence restricts to a bijection between the Birkhoff closure operators on effective equivalence relations and the Birkhoff subcategories of $C$. In this case it is possible to provide an explicit description of the closure, and to characterise the congruence distributive Goursat categories.Comment: 14 pages. Accepted for publication in "Rendiconti dell'Istituto Matematico di Trieste

The snail lemma for internal groupoids

We establish a generalized form both of the Gabriel-Zisman exact sequence associated with a pointed functor between pointed groupoids, and of the Brown exact sequence associated with a fibration of pointed groupoids. Our generalization consists in replacing pointed groupoids with groupoids internal to a pointed regular category with reflexive coequalizer

Homotopy torsion theories

In the context of categories equipped with a structure of nullhomotopies, we introduce the notion of homotopy torsion theory. As special cases, we recover pretorsion theories as well as torsion theories in multi-pointed categories and in pre-pointed categories. Using the structure of nullhomotopies induced by the canonical string of adjunctions between a category A and the category Arr(A) of arrows, we give a new proof of the correspondence between orthogonal factorization systems in A and homotopy torsion theories in Arr(A), avoiding the request on the existence of pullbacks and pushouts in A. Moreover, such a correspondence is extended to weakly orthogonal factorization systems and weak homotopy torsion theories.Comment: 37 pages, comments are welcom

Collagen-based tissue engineering strategies for vascular medicine

Cardiovascular diseases (CVDs) account for the 31% of total death per year, making them the first cause of death in the world. Atherosclerosis is at the root of the most life-threatening CVDs. Vascular bypass/replacement surgery is the primary therapy for patients with atherosclerosis. The use of polymeric grafts for this application is still burdened by high-rate failure, mostly caused by thrombosis and neointima hyperplasia at the implantation site. As a solution for these problems, the fast re-establishment of a functional endothelial cell (EC) layer has been proposed, representing a strategy of crucial importance to reduce these adverse outcomes. Implant modifications using molecules and growth factors with the aim of speeding up the re-endothelialization process has been proposed over the last years. Collagen, by virtue of several favorable properties, has been widely studied for its application in vascular graft enrichment, mainly as a coating for vascular graft luminal surface and as a drug delivery system for the release of pro-endothelialization factors. Collagen coatings provide receptor-ligand binding sites for ECs on the graft surface and, at the same time, act as biological sealants, effectively reducing graft porosity. The development of collagen-based drug delivery systems, in which small-molecule and protein-based drugs are immobilized within a collagen scaffold in order to control their release for biomedical applications, has been widely explored. These systems help in protecting the biological activity of the loaded molecules while slowing their diffusion from collagen scaffolds, providing optimal effects on the targeted vascular cells. Moreover, collagen-based vascular tissue engineering substitutes, despite not showing yet optimal mechanical properties for their use in the therapy, have shown a high potential as physiologically relevant models for the study of cardiovascular therapeutic drugs and diseases. In this review, the current state of the art about the use of collagen-based strategies, mainly as a coating material for the functionalization of vascular graft luminal surface, as a drug delivery system for the release of pro-endothelialization factors, and as physiologically relevant in vitro vascular models, and the future trend in this field of research will be presented and discussed

Tubular Bioartificial Organs: From Physiological Requirements to Fabrication Processes and Resulting Properties. A Critical Review

In this featured review manuscript, the aim is to present a critical survey on the processes available for fabricating bioartificial organs (BAOs). The focus will be on hollow tubular organs for the transport of anabolites and catabolites, i.e., vessels, trachea, esophagus, ureter and urethra, and intestine. First, the anatomic hierarchical structures of tubular organs, as well as their principal physiological functions, will be presented, as this constitutes the mandatory requirements for effectively designing and developing physiologically relevant BAOs. Second, 3D bioprinting, solution electrospinning, and melt electrowriting will be introduced, together with their capacity to match the requirements imposed by designing scaffolds compatible with the anatomical and physiologically relevant environment. Finally, the intrinsic correlation between processes, materials, and cells will be critically discussed, and directives defining the strengths, weaknesses, and opportunities offered by each process will be proposed for assisting bioengineers in the selection of the appropriate process for the target BAO and its specific required functions

RELAÇÃO ENTRE A EDUCAÇÃO INFANTIL E A FAMÍLIA: EM BUSCA DE UMA EDUCAÇÃO ACOLHEDORA.

O propósito deste artigo é apresentar considerações sobre a importância da relação instituição familiar e instituição de educação infantil, com vistas a propiciar à criança uma educação acolhedora. Uma educação que se efetivará com ações de cuidado e acolhimento, afeição e carinho, com a família e a escola assumindo suas responsabilidades e atuando de forma integrada. Para tanto, também apontaremos a indissociabilidade entre educação e cuidado, como uma das formas de potencializar ações que favoreçam a interação humana. Assim, este texto tem como meta se constituir um momento de reflexão para todos os envolvidos na prática educativa, apresentando possibilidades, inquietações, indagações e aspirações para uma educação que se torne mais humana para a criança. Acreditamos que as práticas realizadas num ambiente acolhedor, em que às crianças, suas famílias e professores tenham voz e vez, com possibilidades de compartilhar experiências e ideias transformam a Escola num espaço humanizador

Indústria cultural, currículo e formação de professores: a dimensão ética como articuladora no processo pedagógico

In this article we present and discuss the value of the ethical dimension present as an articulator in the organization of pedagogical work. Considering that Ethics is disfigured by the events and understandings of today's society, in which teachers hide behind masks as proletarians of an unnecessary and useless knowledge for the capital, to analyze the ethical dimension and its importance for the educational process and practice, presenting it as an appreciation of the human being and all its manifestations. Understanding the School as a space of interactions, the curriculum becomes a cultural artifact for the teacher to reach his goal with a humanizing education that aims at the emancipation of the human being.En este artículo presentamos y discutimos el valor de la dimensión ética presente como articuladora en la organización del trabajo pedagógico. Considerando que la Ética está desfigurada por los hechos y entendimientos de la sociedad actual, en que profesores se esconden por detrás de máscaras como proletarios de un conocimiento desnecesario e inútil al capital, analizar la dimensión ética y su importancia para el proceso y para la práctica educacional se presenta como valoración del ser humano y de todas sus manifestaciones. Comprendiendo la Escuela como un espacio de interacciones, el currículo se vuelve un artefacto cultural para que el profesor logre su objetivo con una educación humanizadora y que tiene en cuenta la emancipación del humano.Neste artigo apresentamos e discutimos o valor da dimensão ética presente como articuladora na organização do trabalho pedagógico. Considerando que a Ética está desfigurada pelos acontecimentos e entendimentos da sociedade atual, em que professores se escondem por detrás de máscaras como proletários de um conhecimento desnecessário e inútil ao capital, analisar a dimensão ética e sua importância para o processo e para a prática educativa se apresenta como valorização do ser humano e de todas as suas manifestações. Entendendo a Escola como um espaço de interações, o currículo se torna um artefato cultural para que o professor alcance seu objetivo com uma educação humanizadora e que visa à emancipação do ser humano