In memoriam: Joseph D. Sneed y su revolución en la filosofía de la ciencia contemporánea

El pasado marzo de 2020 falleció en Estados Unidos, su país de origen, el físico y filosofo de la ciencia Joseph D. Sneed, uno de los filósofos de la ciencia más importantes del siglo XX y de lo que va del presente siglo. Este profesor emérito de la Colorado School of Mines nació en 1938, en 1960 se graduó como físico en la Universidad Rice, en 1962 como MS en física en la Universidad de Illinois y en 1964 como PhD en filosofía en la Universidad de Stanford, bajo la dirección de Patrick Suppes.El pasado marzo de 2020 falleció en Estados Unidos, su país de origen, el físico y filosofo de la ciencia Joseph D. Sneed, uno de los filósofos de la ciencia más importantes del siglo XX y de lo que va del presente siglo. Este profesor emérito de la Colorado School of Mines nació en 1938, en 1960 se graduó como físico en la Universidad Rice, en 1962 como MS en física en la Universidad de Illinois y en 1964 como PhD en filosofía en la Universidad de Stanford, bajo la dirección de Patrick Suppes

Strawson’s and searle’s descriptive theories of reference. Two criticisms to the theories of nonsense

En la primera parte del presente artículo se examinan las objeciones de Strawson a la ‘teoría de las  descripciones’ de Russell desde el contexto de una semántica pragmática, enfatizando la importancia de la  distinción fregeana entre implicación lógica y presuposición, además de las críticas de Donnellan, Grice y Devitt  al uso únicamente atributivo (no referencial) de las descripciones por parte de Russell y Strawson. En la  segunda parte, se presenta la teoría de Searle sobre el problema del significado/referencia de los nombres  propios y la aproximación sistemática (axiomática) en el contexto de una teoría de los actos de habla.In the first part of this paper I examine the Strawson’s objections to Russells’ ‘theory of descriptions’ from the  context of a pragmatic semantics emphasizing the importance of the Fregean distinction between logical  implication and presupposition. Furthermore, I examine Donella’s, Grice’s and Devitt’s criticisms to the use  merely attributive (non-referential) of descriptions by Russell and Strawson. In the second part, I present  Searle’s theory on the problem of meaning/reference of proper names and the systematic (axiomatic)  approach in the context of a theory of speech acts

The models of data in scientific theories

En este escrito, me propongo desarrollar una reflexión sobre los modelos de datos (MDs) en las ciencias empíricas destacando su importancia para la representación de los fenómenos de que ellas se ocupan y para la evidencia de estas. Al mismo tiempo, presento y discuto algunas de las críticas que se han planteado a la descripción T-no teórica de las aplicaciones intencionales I en algunas teorías que llevarían a proponer una modificación en la aserción empírica (enunciado Ramsey-Sneed) que acompaña a las teorías, como son los casos de hipótesis aisladas como la ley de Ohm y de teorías físicas máximamente comprensivas y omniabarcantes como las teoría del todo y de gran unificación.This paper intends to develop a reflection on the data models (DMs) in the empirical sciences, highlighting their importance for the representation of the phenomena that they occupy and for the evidence of these. At the same time, I present and discuss some of the criticisms that have been raised about the non-theoretical description of the intentional applications I in some theories that would lead to propose a modification in the empirical assertion (Ramsey-Sneed statement) that accompanies theories, are presented and discussed, as are the cases of isolated hypotheses such as Ohm's law and of maximally comprehensive and all-encompassing physical theories such as the Theory of Everything and of great unification

The logical and epistemological interpretations of Carnap’s Aufbau. A complementary proposal

En este artículo me propongo discutir dos de las grandes interpretaciones del Aufbau, la de Quine (1953, 1969), continuada por muchos anglosajones, que introduce el programa propuesto en el Aufbau en la tradición del empirismo británico destacando sus aspectos epistemo-semánticos y la que, defendida por los neokantianos y, en particular, por Friedman (1997) y Richardson (1998), enfatizan lo estructural o lógico sobre lo epistemológico y semántico. Se trata de dos interpretaciones unilaterales e insuficientes que es preciso complementar e integrar, como se evidencia en el caso de constitución formal de los objetos físicos, haciendo uso de la lógica moderna (teoría de relaciones), la teoría de conjuntos y de la topología como lo hace Carnap en el Aufbau.In this paper, I propose to discuss two of the main interpretations of Carnap’s Aufbau, the one by Quine (1953, 1969), pursued by many anglo-saxon philosophers who introduce the Aufbau´s program in the tradition of british empiricism highlighting its epistemicsemantic aspects and the one advocated by neo-Kantians, specially Friedman (1997) and Richardson (1998), who emphasize the structural or logical over the epistemological and semanticaI.These two interpretations are unilateral and insufficient in need of complementation and integration, as evidenced in the case of the formal constitution of physical objects, using modern logical (relation theory), set theory and topology as does Carnap in the Aufbau

From the reference of terms and statements to the reference of theories: the novelty of sneed’s view

El objeto de este artículo, es realizar una presentación general del problema de los términos teóricos y de  algunos de los problemas causados, por lo que Hempel llamó “el requisito de especificación lingüístico”, así  como la insuficiencia de sus principales soluciones en el marco de lo que se conoce como la filosofía  estándar, tradicional y heredada de la ciencia, destacando de manera especial la solución dada por Ramsey y  la manera como Sneed la reconstruye al parafrasearla en términos modelísticos e introducirle cambios  sustantivos. Como consecuencia de estas modificaciones, conocidas como la “aserción empírica”, que  acompaña la teoría (enunciado Ramsey-Sneed), me interesa mostrar el tránsito desde, una preocupación  filosófica por el referente de los términos o enunciados, a un interés por el referente de las teorías,  diferenciando lo que sería su referente inmediato, a saber, las aplicaciones intencionales o modelos de datos, de su referente mediato, los sistemas empíricos que las aplicaciones intencionales, (modelos de datos) como  una subclase de los modelos potenciales parciales representan, tanto en teorías aisladas, como en redes  teóricas, lo que, para este último caso, supone proponer un nuevo tipo de “aserción empírica”.This paper intends to do a general presentation of the problem of theoretical terms and some of the  problems caused by what Hempel called “requisite of linguistic specification” as well as the insufficiency of  his main solutions in the framework of the received view or standard philosophy of science, giving special  attention to Ramsey´s solution and the way Sneed reworks it by paraphrasing it in modelistic terms and  introducing substantive changes. As a result of these modifications, known as the “empirical assertion”, that  come with the theory (the Ramsey-Sneed assertion), I try to show the change from a philosophical worry for  the referent of terms or statements, to an interest for the referent of theories, distinguishing what it would  be their immediate referent, namely the intensional applications or data models from their mediate referent,  the empirical systems that the intensional applications (data models) represent as a subclass of the potential  models, both in isolated theories and in theoretical nets, what requires to propose a new kind of “empirical  assertion”

Magnetism and superconductivity driven by identical 4ff states in a heavy-fermion metal

The apparently inimical relationship between magnetism and superconductivity has come under increasing scrutiny in a wide range of material classes, where the free energy landscape conspires to bring them in close proximity to each other. This is particularly the case when these phases microscopically interpenetrate, though the manner in which this can be accomplished remains to be fully comprehended. Here, we present combined measurements of elastic neutron scattering, magnetotransport, and heat capacity on a prototypical heavy fermion system, in which antiferromagnetism and superconductivity are observed. Monitoring the response of these states to the presence of the other, as well as to external thermal and magnetic perturbations, points to the possibility that they emerge from different parts of the Fermi surface. This enables a single 4$f$ state to be both localized and itinerant, thus accounting for the coexistence of magnetism and superconductivity.Comment: 4 pages, 4 figure

Methyl Jasmonate and Methyl-β-Cyclodextrin Individually Boost Triterpenoid Biosynthesis in <i>Chlamydomonas Reinhardtii</i> UVM4.

The commercialisation of valuable plant triterpenoids faces major challenges, including low abundance in natural hosts and costly downstream purification procedures. Endeavours to produce these compounds at industrial scale using microbial systems are gaining attention. Here, we report on a strategy to enrich the biomass of the biotechnologically-relevant Chlamydomonas reinhardtii strain UVM4 with valuable triterpenes, such as squalene and (S)-2,3-epoxysqualene. C. reinhardtii UVM4 was subjected to the elicitor compounds methyl jasmonate (MeJA) and methyl-β-cyclodextrine (MβCD) to increase triterpene yields. MeJA treatment triggered oxidative stress, arrested growth, and altered the photosynthetic activity of the cells, while increasing squalene, (S)-2,3-epoxysqualene, and cycloartenol contents. Applying MβCD to cultures of C. reinhardtii lead to the sequestration of the two main sterols (ergosterol and 7-dehydroporiferasterol) into the growth medium and the intracellular accumulation of the intermediate cycloartenol, without compromising cell growth. When MβCD was applied in combination with MeJA, it counteracted the negative effects of MeJA on cell growth and physiology, but no synergistic effect on triterpene yield was observed. Together, our findings provide strategies for the triterpene enrichment of microalgal biomass and medium

A fast stroboscopic spectral method for rotating systems in numerical relativity

We present a numerical technique for solving evolution equations, as the wave equation, in the description of rotating astrophysical compact objects in comoving coordinates, which avoids the problems associated with the light cylinder. The technique implements a fast spectral matching between two domains in relative rotation: an inner spherical domain, comoving with the sources and lying strictly inside the light cylinder, and an outer inertial spherical shell. Even though the emphasis is placed on spectral techniques, the matching is independent of the specific manner in which equations are solved inside each domain, and can be adapted to different schemes. We illustrate the strategy with some simple but representative examples.Comment: 16 pages, 15 figure

The scattering of SH waves by a finite crack with a superposition based diffraction technique

The problem of diffraction of cylindrical and plane SH waves by a finite crack is revisited -- We construct an approximate solution by the addition of independent diffracted terms -- We start with the derivation of the fundamental case of a semi-infinite crack obtained as a degenerate case of generalized wedge -- This building block is then used to compute the diffraction of the main incident waves -- The interaction between the opposite edges of the crack is then considered one term at a time until a desired tolerance is reached -- We propose a recipe to determine the number of required interactions as a function of frequency -- The solution derived with the superposition technique can be applied at low and high frequencie

Three little pieces for computer and relativity

Numerical relativity has made big strides over the last decade. A number of problems that have plagued the field for years have now been mostly solved. This progress has transformed numerical relativity into a powerful tool to explore fundamental problems in physics and astrophysics, and I present here three representative examples. These "three little pieces" reflect a personal choice and describe work that I am particularly familiar with. However, many more examples could be made.Comment: 42 pages, 11 figures. Plenary talk at "Relativity and Gravitation: 100 Years after Einstein in Prague", June 25 - 29, 2012, Prague, Czech Republic. To appear in the Proceedings (Edition Open Access). Collects results appeared in journal articles [72,73, 122-124