Understanding aging and how it affects an organism's lifespan is a fundamental problem in biology. A hallmark of aging is stem cell senescence, the decline of functionality, and number of somatic stem cells, resulting in an impaired regenerative capacity and reduced tissue function. In addition, aging is characterized by profound remodeling of the immune system and a quantitative decline of adequate immune responses, a phenomenon referred to as immune‐senescence. Yet, what is causing stem cell and immune‐senescence? This review discusses experimental (...) studies of potentially immortal Hydra which have made contributions to answering this question. Hydra transcription factor FoxO has been shown to modulate both stem cell proliferation and innate immunity, lending strong support to a role of FoxO as critical rate‐of‐aging regulator from Hydra to human. Constructing a model of how FoxO responds to diverse environmental factors provides a framework for how stem cell factors might contribute to aging. (shrink)

Theoretical minimal RNA rings are candidate primordial genes evolved for non‐redundant coding of the genetic code's 22 coding signals (one codon per biogenic amino acid, a start and a stop codon) over the shortest possible length: 29520 22‐nucleotide‐long RNA rings solve this min‐max constraint. Numerous RNA ring properties are reminiscent of natural genes. Here we present analyses showing that all RNA rings lack dinucleotide CG (a mutable, chemically instable dinucleotide coding for Arginine), bearing a resemblance to known CG‐depleted genomes. CG (...) in “incomplete” RNA rings (not coding for all coding signals, with only 3–12 nucleotides) gradually decreases towards CG absence in complete, 22‐nucleotide‐long RNA rings. Presumably, feedback loops during RNA ring growth during evolution (when amino acid assignment fixed the genetic code) assigned Arg to codons lacking CG (AGR) to avoid CG. Hence, as a chemical property of base pairs, CG mutability restructured the genetic code, thereby establishing itself as genetically encoded biological information. (shrink)

In memoriam José Arrazola Ramírez The logic $\textbf{G}^{\prime}_3$ was introduced by Osorio et al. in 2008; it is a three-valued logic, closely related to the paraconsistent logic $\textbf{CG}^{\prime}_3$ introduced by Osorio et al. in 2014. The logic $\textbf{CG}^{\prime}_3$ is defined in terms of a multi-valued semantics and has the property that each theorem in $\textbf{G}^{\prime}_3$ is a theorem in $\textbf{CG}^{\prime}_3$. Kripke-type semantics has been given to $\textbf{CG}^{\prime}_3$ in two different ways by Borja et al. in 2016. In this work, we (...) continue the study of $\textbf{CG}^{\prime}_3$, obtaining a Hilbert-type axiomatic system and proving a soundness and completeness theorem for this logic. (shrink)

Dieses seit langem angekündigte, in drei Bänden geplante Handbuch, das sein Erscheinen mit dem zweiten Band über das byzantinische Hochmittelalter und die nachbyzantinische Epoche eröffnet, könnte mit seinen betont lapidaren Titel den Eindruck erwecken, erstmalig eine breite oder gar erschöpfende Darstellung der byzantinischen Theologie zu bieten; doch im Unterschied zu H.-G.Becks Klassiker „Kirche und theologische Literatur in byzantinischen Reich“ (München 1959, 1977), in dem ein lückenloser Überblick über die Gesamtheit der theologischen Produktion in Byzanz(330 bzw. Mitte des 6. Jahrhunderts – (...) 1453) angestrebt ist, setzt sich das vorliegende Werk das Ziel, eine Reihe herausragender Theologen eingehend in Biographie und Werkanalyse darzustellen; dabei nehmen die Bearbeiter, wie im Vorwort J. Norets (S. 3f.) betont, an der „Clavis Patrum Graecorum“ Maß, so daß erstmalig alle echten, unechten und zweifelhaften Werke eines Autors dieser Epochen eine feste Nummer tragen, der dann noch Angaben zu den Handschriften, evtl. Editionen und Übersetzungen folgen. Als weiteres Neuheitsmerkmal ist eine umfassende, internationale Bibliographie zu jedem behandelten Autor beigegeben. Diese immense Arbeitsleistung konnte nur auf möglichst viele Mitarbeiter und Berater, besonders aus dem Forschungspersonal der „Ecole pratique des Hautes Etudes“ und des „Centre National de la Recherche Scientifique“, verteilt werden, die neben den ausländischen Kollegen in den Einführungen und Danksagungen (S. 1–6) erwähnt werden. Andererseits besitzen die seitenlangen bibliographischen Listen leider nicht den Charakter einer „Bibliographie raisonnée“, insofern wichtige und unwichtige Titel gleichberechtigt nebeneinanderstehen; nur in Einzelfällen sind auch kritische Rezensionen mitberücksichtigt. (shrink)

For $\Bbb {F}$ the field of real or complex numbers, let $CG(\Bbb {F})$ be the continuous geometry constructed by von Neumann as a limit of finite dimensional projective geometries over $\Bbb {F}$ . Our purpose here is to show the equational theory of $CG(\Bbb {F})$ is decidable.

Paraconsistent extensions of 3-valued Gödel logic are studied as tools for knowledge representation and nonmonotonic reasoning. Particularly, Osorio and his collaborators showed that some of these logics can be used to express interesting nonmonotonic semantics. CG’3 is one of these 3-valued logics. In this paper, we introduce Fidel semantics for a certain calculus of CG’3 by means of Fidel structures, named CG’3-structures. These structures are constructed from enriched Boolean algebras with a special family of sets. Moreover, we also show that (...) the most basic CG’3-structures coincide with da Costa–Alves’ bi-valuation semantics; this connection is displayed through a Representation Theorem for CG’3-structures. By contrast, we show that for other paraconsistent logics that allow us to present semantics through Fidel structures, this connection is not held. Finally, Fidel semantics for the first-order version of the logic of CG’3 are presented by means of adapting algebraic tools. (shrink)

The aim of this paper is to show the incompleteness of the exclusively logico-syntactical and logico-semantical approaches to one of the core issues of philosophy of science, namely, scientific laws and scientific explanation in C. G. Hempel’s works. I start with a brief exposition of the main characteristics of Hempel’s approach to deductive explanations based on universal scientific laws and then analyze the problems and paradoxes inherent in this approach. Next, I trace these characteristics back to Hempel’s and Carnap’s attempts (...) to ground the concepts of scientific law and explanation exclusively on logic , which led to a highly normative approach alienated from the practice of real science. (shrink)

This paper analyses the features of the 2021 software for the creation of ultrarealistic digital characters “MetaHuman Creator” and reflects on the causes of such perceived effect of realism to understand if the faces produced with such software represent an actual novelty from an academic standpoint. Such realism is first of all defined as the result of semio-cognitive processes which trigger interpretative habits specifically related to faces. These habits are then related to the main properties of any realistic face: being (...) face-looking, face-meaning and face-acting. These properties, in turn, are put in relation with our interactions with faces in terms of face detection, face recognition, face reading and face agency. Within this theoretical framework, we relate the characteristics of these artificial faces with such interpretative habits. To do so, we first of all make an examination of the technological features behind both the software and the digital faces it produces. This analysis highlights four main points of interest: the mathematical accuracy, the scanned database, the high level of details and the transformative capacities of these artificial faces. We then relate these characteristics with the cultural and cognitive aspects involved in recognizing and granting meaning to faces. This reveals how metahuman faces differs from previous artificial faces in terms of indexicality, intersubjectivity, informativity and irreducibility. But it also reveals some limits of such effect of reality in terms of intentionality and historical context. This examination consequently brings us to conclude that metahuman faces are qualitatively different from previous artificial faces and, in the light of their potentials and limits, to highlight four main lines of future research based on our findings. (shrink)