Higher-order Lorentz-invariance violation, quantum gravity and fine-tuning

The issue of Lorentz fine-tuning in effective theories containing higher-order operators is studied. To this end, we focus on the Myers-Pospelov extension of QED with dimension-five operators in the photon sector and standard fermions. We compute the fermion self-energy at one-loop order considering its even and odd $CPT$ contributions. In the even sector we find small radiative corrections to the usual parameters of QED which also turn to be finite. In the odd sector the axial operator is shown to contain unsuppressed effects of Lorentz violation leading to a possible fine-tuning. We use dimensional regularization to deal with the divergencies and a generic preferred four-vector. Taking the first steps in the renormalization procedure for Lorentz violating theories we arrive to acceptable small corrections allowing to set the bound $\xi<6 \times10^{-3}$.Comment: 11 pages, new version with the correct pole extractio

Polymer quantization, stability and higher-order time derivative terms

The stability of higher-order time derivative theories using the polymer extension of quantum mechanics is studied. First, we focus on the well-known Pais-Uhlenbeck model and by casting the theory into the sum of two decoupled The possibility that fundamental discreteness implicit in a quantum gravity theory may act as a natural regulator for ultraviolet singularities arising in quantum field theory has been intensively studied. Here, along the same expectations, we investigate whether a nonstandard representation, called polymer representation can smooth away the large amount of negative energy that afflicts the Hamiltonians of higher-order time derivative theories; rendering the theory unstable when interactions come into play. We focus on the fourth-order Pais-Uhlenbeck model which can be reexpressed as the sum of two decoupled harmonic oscillators one producing positive energy and the other negative energy. As expected, the Schrodinger quantization of such model leads to the stability problem or to negative norm states called ghosts. Within the framework of polymer quantization we show the existence of new regions where the Hamiltonian can be defined well bounded from below.Comment: 13 pages, 2 figure

Performativity and Intimacy in Paid Domestic Work: Negotiating the Reproduction of Difference in Chile

The purpose of this thesis is to analyse the performative role of paid domestic work within upper-class families in Santiago, Chile in the reproduction of national narratives and difference. In 2005, Staab and Maher identified the Chilean version of the ‘servant problem’. Old and new middle- and upper-class families were struggling to find good servants; those who knew their subordinate place and performed their duties with a servile attitude. Chilean nanas, a pejorative and reiterative form of naming paid domestic workers, were no longer docile young women from rural areas; now, Staab and Maher (2005) wrote, the perception of employers was that these women knew too much about their rights and were from dangerous urban areas marked by violence and uncivilised forms of living. In addition, as the deceased poet Lemebel noted, workers were starting to behave and look like upper-class women; wearing similar clothes, going to the gym, or dyeing their hair blond. This thesis explores the routinised and repetitive acts of atonement of class and racial difference within employer/worker relations in a neoliberal Chile. It is argued that upper-class families continue to be the national norm lived in modern times through the reproduction of a culture of servitude (Camus and de la O Martinez, 2014), and that today survives and recreates the neoliberal ‘white gendered Chilean dream’ through the figure of the Chilean happy family. It is precisely this continuity of a culture of servitude that paid domestic work maintains, that enables the Chilean State to portray itself as modern and gender-friendly, with upper-class women becoming modern women – seemingly achieving forms of gender equality – while patriarchal and racist arrangements continue within the home and the nation. This thesis draws upon the theoretical work of Gutiérrez (2010) on affective labour, of Butler (1999) on performativity, of Berlant (2011) on intimacy and politics, and of Stoler (2009) on intimacy and coloniality. It uses interviews with upper-class female employers and with domestic workers

SinEx DB: a database for single exon coding sequences in mammalian genomes

Indexación: Web of Science.Eukaryotic genes are typically interrupted by intragenic, noncoding sequences termed introns. However, some genes lack introns in their coding sequence (CDS) and are generally known as 'single exon genes' (SEGs). In this work, a SEG is defined as a nuclear, protein-coding gene that lacks introns in its CDS. Whereas, many public databases of Eukaryotic multi-exon genes are available, there are only two specialized databases for SEGs. The present work addresses the need for a more extensive and diverse database by creating SinEx DB, a publicly available, searchable database of predicted SEGs from 10 completely sequenced mammalian genomes including human. SinEx DB houses the DNA and protein sequence information of these SEGs and includes their functional predictions (KOG) and the relative distribution of these functions within species. The information is stored in a relational database built with My SQL Server 5.1.33 and the complete dataset of SEG sequences and their functional predictions are available for downloading. SinEx DB can be interrogated by: (i) a browsable phylogenetic schema, (ii) carrying out BLAST searches to the in-house SinEx DB of SEGs and (iii) via an advanced search mode in which the database can be searched by key words and any combination of searches by species and predicted functions. SinEx DB provides a rich source of information for advancing our understanding of the evolution and function of SEGs.https://academic.oup.com/database/article-lookup/doi/10.1093/database/baw09

La dette, les ajustements et le commerce de l’Amérique latine face à l’Europe

The autor propose a global approach in analysing the main economic problems that Latin America was confonted with for the past years, prablems such as foreing debt, structural adjustment, obstacles to foreing trade or the destruction of environment, related to the modalities of the region’s integration in the international economy. The autor also question himself on the rale that Europe and the european economic actors play in solving or worsening these problems. This way, topics such as the impact of the european neo-protectionismpolicies regarding Latin America exports, the support of governement to adjustment policies within international financial institutions, the particularly active role of certain european banks in the unofficial trading in debts and the conversion of unrepaid loans when repurchasing compagnias or the sharing of costs related to envorenment protection. In response to the often contradictory european policies, the autor argues in favour of a reonforcement of international cooperation, and also of having the Latin-american population taking the responsability of their own destiny

Vortex pinning in high-Tc materials via randomly oriented columnar defects, created by GeV proton-induced fission fragments

Extensive work has shown that irradiation with 0.8 GeV protons can produce randomly oriented columnar defects (CD's) in a large number of HTS materials, specifically those cuprates containing Hg, Tl, Pb, Bi, and similar heavy elements. Absorbing the incident proton causes the nucleus of these species to fission, and the recoiling fission fragments create amorphous tracks, i.e., CD's. The superconductive transition temperature Tc decreases linearly with proton fluence and we analyze how the rate depends on the family of superconductors. In a study of Tl-2212 materials, adding defects decreases the equilibrium magnetization Meq(H) significantly in magnitude and changes its field dependence; this result is modeled in terms of vortex pinning. Analysis of the irreversible magnetization and its time dependence shows marked increases in the persistent current density and effective pinning energy, and leads to an estimate for the elementary attempt time for vortex hopping, tau ~ 4x10^(-9) s.Comment: Submitted to Physica C; presentation at ISS-2001. PDF file only, 13 pp. tota

Evaluacion de la biocalidad para la conservacion en un bosque nativo costero, Region del Maule

96 p.La distribución espacial de la vegetación chilena modelada por la topografía y el bioclima se incluye en diferentes zonas climático-vegetacionales. Dentro de éstas está la mesomórfica o mediterránea de interés taxonómico, biogeográfico, ecológico y conservación de la biodiversidad. En relación con la flora vascular se concentra aquí el mayor número de endemismos siendo relevante la contribución del bosque maulino costero de la Región del Maule. Este bosque es parte del área templada de Chile que se incluye dentro de los denominados “hotspots” para la conservación de la biodiversidad. Se aplicó el método del sondeo botánico rápido en parcelas circulares de 20 m de radio, en 157 sitios de las Cordillera de la Costa de la Región del Maule. En este sondeo se registraron y colectaron especies vasculares tanto en el bosque como en el matorral nativo. La información se organizó en una base de datos donde se analizó la riqueza y biocalidad según etodología europea. Sobre la base del carácter endémico o nativo, distribución, abundancia y rareza de las especies según la literatura, se aplicó una escala ad-hoc para generar una nueva propuesta de priorización de conservación simbolizada con estrellas de color cuyo orden decreciente de prioridad es negro, dorado, azul y verde. Al mismo tiempo se determinó el esfuerzo de muestreo y los índices de endemismos, invasión y rareza de las especies. El esfuerzo de muestreo alcanzó a 96% demostrando confiabilidad en la información. Para 166 especies vasculares leñosas se encontró que con prioridad de conservación son 14 (estrellas negras) y de los 157 sitios 145 tienen importancia, dado el contenido de biocalidad de las especies. Los resultados incluyen las áreas protegidas y las especies hasta ahora mencionadas por la literatura y por los organismos encargados de proteger, supervisar y administrar los recursos naturales del país. Esta metodología permite actualizar la información sobre el estado de conservación de las especies, la cual demostró la vulnerabilidad del bosque maulino en cuanto a su integridad y cobertura, así como el alto porcentaje de endemismo (50%)./ SUMMARY: The space distribution of the Chilean vegetation is modeled by the topography and the Bioclimate and includes different climate zones and vegetations. This includes the Mediterranean Climate, which has biogeographical, ecological and conservation of biodiversity. In relation to the vascular flora the greater number of endemics incluye the temperate areas of Chile where hotspots that are concentrated here are an excellent contribution to the coastal maulino forest in the Maule Region. The coast of the Maule Region include 157 sites of native forests and scrubs. Botanical sounding species were registered and collected here as well. The information was organized in a data base where it analyzes the richness and the bioquality of the species based on herbal and land observation. On the base of the endemic or native character, distribution, abundance and peculiarity of the species was applied to generate a new proposal of prioritization of conservation. This was symbolized with star colors whose decreasing order of priority is black, gold, blue and green. At the same time one determined the effort of sampling (rarefaction) and the indices endemism, invasion and peculiarity of the species. The sample effort reached 96% which demonstratesthat the information is trustworthy. From 166 species, 14 (black stars) have conservation priority and from 157 samples, 145 were given bio quality importance The results include the protected areas and the species mentioned in textbooks and the organisms related to the natural resources. The methodology allows the information on the state of conservation and species demonstrating vulnerability in the Maulino Forrest to be updated. The justification to conserve the Maulino Forest in its present state of fragmentation is also endorsed by the endemics index with 50% of endemic species (82 sp.