The Galactic evolution of sulphur as traced by globular clusters

Sulphur is an important, volatile alpha element but its role in the Galactic chemical evolution is still uncertain. We derive the S abundances in RGB stars in three Galactic globular clusters (GC) that cover a wide metallicity range (-2.3<[Fe/H]<-1.2), namely M4, M22, and M30. The halo field stars show a large scatter in the [S/Fe] ratio in this metallicity span, which is inconsistent with canonical chemical evolution models. To date, very few measurements of [S/Fe] exist for stars in GCs, which are good tracers of the chemical enrichment of their environment. However, some light and alpha elements show star-to-star variations within individual GCs and it is yet unclear whether sulphur also varies between GC stars. We used the the infrared spectrograph CRIRES to obtain high-resolution (R~50000), high signal-to-noise (SNR~200 per px) spectra in the region of the S I multiplet 3 at 1045 nm for 15 GC stars selected from the literature (6 stars in M4, 6 stars in M22 and 3 stars in M30). Multiplet 3 is better suited for S abundance derivation than the more commonly used lines of multiplet 1 at 920 nm, since its lines are not blended by telluric absorption or other stellar features at low metallicity. We used spectral synthesis to derive the [S/Fe] ratio of the stars assuming local thermodynamic equilibrium (LTE). We find mean [S/Fe] = 0.58 +/- 0.01 +/- 0.20 dex (statistical and systematic error) for M4, [S/Fe] = 0.57+/-0.01+/-0.19 dex for M22, and [S/Fe] = 0.55+/-0.02+/-0.16 dex for M30. The negative NLTE corrections are estimated to be in the order of the systematic uncertainties. With the tentative exception of two stars with measured high S abundances, we conclude that sulphur behaves like a typical alpha element in the studied Galactic GCs, showing enhanced abundances with respect to the solar value at metallicities below [Fe/H] = -1.0 dex without a considerable spread.Comment: 9 pages, 7 figures, accepted for publication in A&

Default Meanings and the Semantics/Pragmatics Distinction

My thesis is in the area of the Pragmatics of language and communication, i.e. the area of philosophy of language and linguistics which is concerned with the use and understanding of language. In the last decades, and particularly spurred by the works of the so-called ordinary language philosophers (especially Paul Grice), a widespread debate arose about how to treat cases of so called semantic underdetermined meanings. Roughly, these correspond to everyday situations in which the intended meaning of a particular utterance in conversation is richer than the conventional one. In this area of study, the specific topic of my thesis is the one of default meanings, i.e. those enriched interpretations which are arrived at immediately and without any apparent inferential effort. My main research question is: is it in principle possible to treat (also in a formally accurate way) the phenomenon of default meanings? The first chapter of my thesis is a detailed outline concerning Grice’s theory of meaning and communication. The received view about Grice’s picture is exposed and several objections and counter-examples to this view are presented in order to introduce contemporary developments in the semantics/pragmatics debate. In particular, Grice’s theory of conversational implicature is questioned, starting from the acknowledgment of a kind of circularity in the way Grice shapes the distinctions between the layers of meaning: namely, sentence meaning, what is said and what is implicated. From a theoretical perspective, the debate about the semantics/pragmatics distinction and about semantic underdeterminacy in the contemporary post-Gricean Pragmatics is very broad and articulated: a number of general paradigms are available, the most influential being Relevance Theory, truth-conditional pragmatics, hidden indexicalism, semantic minimalism, Discourse Representation Theory. Within these theories, many scholars developed their own proposals, each by focusing on a specific side of the theoretical prism: be that cognitive concerns, linguistic or philosophical topics. In the second chapter of the thesis I analyse in depth these paradigms and tried to put them to the test of a wide case study. The topic of default is introduced in this chapter with respect to Levinson’s influential theory of generalized conversational implicature (GCI). It is explained how, in Levinson’s view, Gricean GCIs represent a kind of automatic inferences, which are induced by some peculiar heuristics. Specific objections undermining such approach are presented and Levinson’s view is eventually rejected. In the third chapter, I put to test the idea of default interpretations and the modelling that has been proposed, with the help of the formal apparatus of dynamic logic in the framework of so-called Default Semantics. It is shown how a radically different approach to the problem of semantic underdeterminacy is possible when some of the standardly accepted (and rarely questioned) presuppositions of semantic theory are put into question and finally rejected in favour of a more fine-grained and dynamic approach to natural language semantics. Default Semantics starts from the acknowledgment of so-called merger representations as the basic units of compositional meaning of acts of communication. Merger representations are illustrated by DRT-Style Diagrams, with the proviso that each component of such single-level semantic representation can stem from different sources (including word meaning and sentence structure as well as pragmatic inference, and various types of default interpretations), none of which enjoy a compositional privilege over the others. It is argued that the variety of ‘defaults’ in Default Semantics are of the deepest theoretical interest. That is why they are especially intended to preserve the undeniable advantages of a principle of compositionality in semantic analysis and at the same time to take seriously into account the linguistic underspecification of utterance meaning. Such task is pursued by resorting to a solid formalism, which is claimed to be able to cope with the various kinds of pragmatic contribution to utterance meaning. My conclusion is that a large case study in Pragmatics is susceptible to treatment of the basis of such merger representations and defaults, and that this approach of this kind can help to get a more fine-grained position about the Semantics/Pragmatics boundary, while saving what good has been proposed from the opposite fronts of the debate

An investigation of the formation and line properties of MgH in 3D hydrodynamical model stellar atmospheres

Studies of the isotopic composition of magnesium in cool stars have so far relied upon the use of one-dimensional (1D) model atmospheres. Since the isotopic ratios derived are based on asymmetries of optical MgH lines, it is important to test the impact from other effects affecting line asymmetries, like stellar convection. Here, we present a theoretical investigation of the effects of including self-consistent modeling of convection. Using spectral syntheses based on 3D hydrodynamical CO$^5$BOLD models of dwarfs (4000K$\lesssim T_\mathrm{eff}\lesssim5160K$, $4.0\leq$log(g)$\leq4.5$, $-3.0\leq[\mathrm{Fe/H}]\leq-1.0$) and giants ($T_\mathrm{eff}\sim4000$K, log(g)$=1.5$, $-3.0\leq[\mathrm{Fe/H}]\leq-1.0$), we perform a detailed analysis comparing 3D and 1D syntheses. We describe the impact on the formation and behavior of MgH lines from using 3D models, and perform a qualitative assessment of the systematics introduced by the use of 1D syntheses. Using 3D model atmospheres significantly affect the strength of the MgH lines, especially in dwarfs, with 1D syntheses requiring an abundance correction of up to +0.69 dex largest for our 5000K models. The corrections are correlated with $T_\mathrm{eff}$ and are also affected by the metallicity. The shape of the strong $^{24}$MgH component in the 3D syntheses is poorly reproduced in 1D. This results in 1D syntheses underestimating $^{25}$MgH by up to $\sim5$ percentage points and overestimating $^{24}$MgH by a similar amount for dwarfs. This discrepancy increases with decreasing metallicity. $^{26}$MgH is recovered relatively well, with the largest difference being $\sim2$ percentage points. The use of 3D for giants has less impact, due to smaller differences in the atmospheric structure and a better reproduction of the line shape in 1D.Comment: 20 pages, 15 figures, accepted for publication in Ap

The solar photospheric abundance of phosphorus: results from co5bold 3D model atmospheres

aims: We determine the solar abundance of phosphorus using co5bold 3D hydrodynamic model atmospheres. method: High resolution, high signal-to-noise solar spectra of the PI lines of Multiplet 1 at 1051-1068 nm are compared to line formation computations performed on a co5bold solar model atmosphere. results: We find A(P)=5.46+- 0.04, in good agreement with previous analysis based on 1D model atmospheres, due to the fact that the PI lines of Mult. 1 are little affected by 3D effects. We cannot confirm an earlier claim by other authors of a downward revision of the solar P abundance by 0.1 dex employing a 3D model atmosphere. Concerning other stars, we found modest (<0.1 dex) 3D abundance corrections for P among four F dwarf model atmospheres of different metallicity, being largest at lowest metallicity. conclusions: We conclude that 3D abundance corrections are generally rather small for the PI lines studied in this work. They are marginally relevant for metal-poor stars, but may be neglected in the Sun

Capability based-approach: re-Invent people and materials viable relationships

Sustainability as an approach to the contemporary textile and fashion design; not only linked to the environmental vision but concerning the economy, respect for people's work and production. “A new dominant social paradigm (DSP) would focus on creating apparel products that are more efficient in material use, production and consumer utility, as well as better meeting the human needs of the consumer base, inherently more social than material needs. Similarly, clothing education in the dominant new social paradigm would promote the development of skills that would most likely include understanding human needs and ecosystem limitations, working collaboratively with the market rather than trying to dominate it and an understanding of local culture and tradition " (LeHew, 2011).Sustentabilidade como abordagem ao design contemporâneo têxtil e de moda; não só ligada à visão ambiental, mas no que diz respeito à economia, ao respeito pelo trabalho das pessoas e à produção. “Um novo paradigma social dominante (DSP) se concentraria na criação de produtos de vestuário mais eficientes no uso de materiais, produção e utilidade para o consumidor, bem como em atender melhor às necessidades humanas da base de consumidores, inerentemente mais sociais do que materiais. Da mesma forma, a educação do vestuário no novo paradigma social dominante, promoveria o desenvolvimento de habilidades que provavelmente incluiriam a compreensão das necessidades humanas e das limitações do ecossistema, trabalhando em colaboração com o mercado ao invés de tentar dominá-lo e uma compreensão da cultura e tradição local "(LeHew , 2011)

Elevated r-process enrichment in Gaia Sausage and Sequoia

The Gaia Sausage and the Sequoia represent the major accretion events that formed the stellar halo of the Milky Way. A detailed chemical study of these main building blocks provides a pristine view of the early steps of the Galaxy's assembly. We present the results of the analysis of the UVES high-resolution spectroscopic observations at the 8.2m VLT of 9 Sausage/Sequoia members selected kinematically using Gaia DR2. We season this set of measurements with archival data from Nissen &amp; Schuster (2011) and GALAH DR3 (2020). Here, we focus on the neutron-capture process by analysing Sr, Y, Ba and Eu behavior. We detect clear enhancement in Eu abundance ([Eu/Fe]~0.6-0.7) indicative of large prevalence of r-process in the stellar n-capture makeup. We are also able to trace the evolution of the heavy element production across a wide range of metallicity. Barium to europium ratio changes from a tight, flat sequence with [Ba/Eu]=-0.7 reflecting dominant core-collapse SNe contribution, to a clear upturn at higher iron abundances, betraying the onset of contamination from asymptotic giant branch (AGB) ejecta. Additionally, we discover two clear sequences in [Fe/H]-[Ba/Fe] plane likely caused by distinct levels of s-process pollution and mixing within the GS progenitor