tRNA 3\u27-amino-tailing for stable amino acid attachment.

Amino acids are attached to the tRNA 3\u27-end as a prerequisite for entering the ribosome for protein synthesis. Amino acid attachment also gives tRNA access to nonribosomal cellular activities. However, the normal attachment is via an ester linkage between the carboxylic group of the amino acid and the 3\u27-hydroxyl of the terminal A76 ribose in tRNA. The instability of this ester linkage has severely hampered studies of aminoacyl-tRNAs. Although the use of 3\u27-amino-3\u27-deoxy A76 in a 3\u27-amino-tailed tRNA provides stable aminoacyl attachment via an amide linkage, there are multiple tailing protocols and the efficiency of each relative to the others is unknown. Here we compare five different tailing protocols in parallel, all dependent on the CCA-adding enzyme [CTP(ATP): tRNA nucleotidyl transferase; abbreviated as the CCA enzyme] to exchange the natural ribose with the modified one. We show that the most efficient protocol is achieved by the CCA-catalyzed pyrophosphorolysis removal of the natural A76 in equilibrium with the addition of the appropriate ATP analog to synthesize the modified 3\u27-end. This protocol for 3\u27-amino-tailing affords quantitative and stable attachment of a broad range of amino acids to tRNA, indicating its general utility for studies of aminoacyl-tRNAs in both canonical and noncanonical activities

Viscose Rayon: An Absorbing Problem. An Investigation into the Impact Conservation Wet Cleaning Treatments have on Historic Woven Viscose Rayon Fabrics; with a Supplementary Analysis of Current Techniques for Identifying Man-Made Fibres

Viscose rayon has been in production for over a century, however, minimal literature is available on its conservation. Pre-1940s viscose rayon has poorer wet strength than later versions. The fiber’s manufacture has influence on its wet strength and progressive improvements to processing methods have improved this characteristic. The implications for conservation wet cleaning treatments on examples from different eras were investigated. Tensile strength testing was conducted on three sets of specimens from different times – c.1940s, c.1960s and c.1980/90s – each subjected to a controlled wet cleaning treatment. Results showed the two later viscose rayons lost significant strength in the wet state, up to 50%. The c.1940s fabric had a greater strength reduction of around 80% - however, degradation from a black colorant present affected the results. This highlighted the risk that degradation, even when not visible macroscopically, can become significantly exacerbated in wetted viscose rayon. Further tensile tests on specimens subjected to wet cleaning and then air dried showed a return of strength upon drying, suggesting that no apparent immediate permanent impact was had on fibers. This research has shown it can be suitable to wet clean viscose rayon, although such treatment may be less appropriate for older more degraded versions

An Ultra Fast Image Generator (UFig) for wide-field astronomy

Simulated wide-field images are becoming an important part of observational astronomy, either to prepare for new surveys or to test measurement methods. In order to efficiently explore vast parameter spaces, the computational speed of simulation codes is a central requirement to their implementation. We introduce the Ultra Fast Image Generator (UFig) which aims to bring wide-field imaging simulations to the current limits of computational capabilities. We achieve this goal through: (1) models of galaxies, stars and observational conditions, which, while simple, capture the key features necessary for realistic simulations, and (2) state-of-the-art computational and implementation optimizations. We present the performances of UFig and show that it is faster than existing public simulation codes by several orders of magnitude. It allows us to produce images more quickly than SExtractor needs to analyze them. For instance, it can simulate a typical 0.25 deg^2 Subaru SuprimeCam image (10k x 8k pixels) with a 5-sigma limiting magnitude of R=26 in 30 seconds on a laptop, yielding an average simulation time for a galaxy of 30 microseconds. This code is complementary to end-to-end simulation codes and can be used as a fast, central component of observational methods relying on simulations.Comment: Submitted to Astronomy and Computing. 13 pages, 9 figure

The Austrian Constitutional Convention: continuing the path to reform the Federal State

Aquest article tracta els diferents debats i intents de reforma del sistema federal austríac dels darrers quinze anys. L’article parteix d'una perspectiva històrica que descriu els desenvolupaments més rellevants del federalisme austríac en el decurs del segle XX, i destaca la importància del procés de centralització a través de la constant transferència de competències des dels Länder al Govern federal, així com els diversos debats en aquest sentit. Segons l’autora, des de 1995, any de l’accés d’Àustria a la Unió Europea, s’han perdut dues grans oportunitats per dur a terme una reforma general del sistema federal que pogués contribuir a compensar el procés de centralització. La primera oportunitat perduda té referència directa amb la Unió Europea. Els Länder van accedir a l’adhesió amb la condició que la Constitució federal preveiés des de diverses dimensions la seva participació en els processos europeus de presa de decisions, tot deixant de banda l’oportunitat d’aprofitar el debat i pressionar per a una reforma estructural del sistema federal. La segona oportunitat perduda té a veure amb la dispersió de propostes resultants dels treballs de la Convenció Constitucional Austríaca. La Convenció, creada el 2003, tenia la missió de discutir la reforma de la Constitució en els aspectes que regulen l’estructura federal del país i, en conseqüència, elaborar- ne un primer esborrany. La incapacitat d’establir i definir eixos comuns de reforma, juntament amb la manca de flexibilitat i de cerca de compromís polític, van desdibuixar el paper de la Convenció.This article discusses the different debates and attempts to reform the Austrian federal system over the last fifteen years. The article is based on a historical perspective that describes the most relevant developments of Austrian federalism during the 20th century, highlighting the importance of the centralisation process through the constant transfer of powers from the Länder to the Federal Government, as well as various debates in this regard. According to the author, since 1995, the year of Austrian adhesion to the European Union, two opportunities have been missed to carry out a general reform of the federal system which could contribute to compensating the centralisation process. The first missed opportunity is directly related to the Austrian adhesion to the European Union. The Länder agreed to the adhesion under the condition that the Federal Constitution would include their participation in European decision-making processes. By focussing on this point, the Länder set aside the opportunity to take advantage of the debate and, as a consequence, press for structural reform of the federal system. The second missed opportunity was related to the dispersion of proposals resulting from the work of the Austrian Constitutional Convention. The Convention, created in 2003, had the mission of discussing those aspects of the reform of the Constitution that regulated the federal structure of the country and, as a consequence, of making a first draft reform. The incapability of establishing and defining common ground for reform, together with the lack of flexibility and of seeking political commitment, weakened the role of the Convention and, thus, any possibility to carry on with the reform

Recensions

Obra ressenyada: Jaume CASALS, El pou de la paraula. Una història de la saviesa grega. Barcelona: Edicions 62, 1996

Ressenyes

Obra ressenyada: Joan PRAT (coord.); Montse ANGUERA,; Felip R. CAUDET ; Dominika DITTWALD ; Jose RECHE ; Inés TOMÀS ; Iolanda VIVANCOS, Els nous imaginaris culturals: espiritualitats orientals, teràpies naturals i sabers esotèrics. Tarragona: Universitat Rovira i Virgili, 2012