Selenocysteine, pyrrolysine and the unique energy metabolism of methanogenic archaea

Methanogenic archaea are a group of strictly anaerobic microorganisms characterized by their strict dependence on the process of methanogenesis for energy conservation. Among the archaea, they are also the only known group synthesizing proteins containing selenocysteine or pyrrolysine. All but one of the known archaeal pyrrolysine-containing and all but two of the confirmed archaeal selenocysteine-containing protein are involved in methanogenesis. Synthesis of these proteins proceeds through suppression of translational stop codons but otherwise the two systems are fundamentally different. This paper highlights these differences and summarizes the recent developments in selenocysteine- and pyrrolysine-related research on archaea and aims to put this knowledge into the context of their unique energy metabolism

Population ageing and public pension reforms in a small open economy

This paper aims to address the issue of public pension reforms under demographic ageing that is likely to occur in Europe over the next 50 years. Three possible scenarios are analysed in a Blanchard OLG framework. These include: i) a decrease both in public pensions and the lump sum labour income tax, ii) a decrease both in public pensions and the distortionary corporate tax, iii) an increase in the retirement age. The analysis focuses on the effects of these fiscal policies on key economic variables such as consumption, private and public debt, output and wages. Quantitative experiments assess the impact of different fiscal policies in terms of public debt sustainability but most importantly suggest policies that smooth the transition of the economy to the new equilibrium. The main results suggest that the adverse effects of pension reforms on consumption are moderated when they are accompanied by appropriate taxation policies. In particular, when the tax response is rapid most of the adverse movement in consumption is avoided while public and national debt reach lower equilibrium levels

Short- and long-run determinants of sovereign debt credit ratings

We study the determinants of sovereign debt ratings from the three main international rating agencies, for the period 1995-2005. Using linear and ordered response models we employ a specification that allows us to distinguish between short and long-run effects, on a country’s rating, of macroeconomic and fiscal variables. The results point to a good performance of the models in explaining a country’s rating, both across agencies and time. Changes in GDP per capita, GDP growth, government debt, and government balance have a short-run impact on a country’s credit rating, while government effectiveness, external debt, foreign reserves and default history are important long-run determinants

Child’s play: Exposure to household pesticide use among children in rural, urban and informal areas of South Africa

Background. As part of a larger dermatological investigation undertaken in 1999 - 2001 involving the Department of Dermatology, Groote Schuur Hospital (Cape Town, South Africa) and Nottingham University (UK), household pesticide use was investigated among Xhosa-speaking families living in three areas in South Africa (a rural area, an urban township and an informal settlement).Objectives. The aim was to characterise pesticide use patternsand potential exposures through skin absorption, ingestion and inhalation for this group of South African children.Methods. A standardised questionnaire, which included a section investigating household pesticide use, was administered by four trained fieldworkers to the parents/guardians of the 740 children (25%) aged between 3 and 11 years identified as having atopic dermatitis either by clinical examination or according to the UK criteria (rural N=387,urban N=292, informal N=61).Results. Of the children with atopic dermatitis, 539 (73%) had been exposed to household pesticides. Most childhood exposure (89%) occurred in the informal settlements, followed by 78% in the urban area and 63% in the rural area.Conclusions. This research highlighted considerable home environment pesticide exposure of South African children in lower socio-economic groups in rural, urban and informal areas. As children are particularly vulnerable to the short- and long-term health effects of pesticide exposure, further indepth investigation is needed to ascertain and document the health effects associated with such exposure in the home

Nonequilibrium effects due to charge fluctuations in intrinsic Josephson systems

Nonequilibrium effects in layered superconductors forming a stack of intrinsic Josephson junctions are investigated. We discuss two basic nonequilibrium effects caused by charge fluctuations on the superconducting layers: a) the shift of the chemical potential of the condensate and b) charge imbalance of quasi-particles, and study their influence on IV-curves and the position of Shapiro steps.Comment: 17 pages, 2 figures, revised version slightly shortene

Measuring Luttinger Liquid Correlations from Charge Fluctuations in a Nanoscale Structure

We suggest an experiment to study Luttinger liquid behavior in a one-dimensional nanostructure, avoiding the usual complications associated with transport measurements. The proposed setup consists of a quantum box, biased by a gate voltage, and side-coupled to a quantum wire by a point contact. Close to the degeneracy points of the Coulomb blockaded box, and in the presence of a magnetic field sufficiently strong to spin polarize the electrons, the setup can be described as a Luttinger liquid interacting with an effective Kondo impurity. Using exact nonperturbative techniques we predict that the differential capacitance of the box will exhibit distinctive Luttinger liquid scaling with temperature and gate voltage.Comment: REVTeX, 4 pages, 1 figure included. Final version, two references adde

Charge-imbalance effects in intrinsic Josephson systems

We report on two types of experiments with intrinsic Josephson systems made from layered superconductors which show clear evidence of nonequilibrium effects: 1. In 2-point measurements of IV-curves in the presence of high- frequency radiation a shift of the voltage of Shapiro steps from the canonical value hf/(2e) has been observed. 2. In the IV-curves of double-mesa structures an influence of the current through one mesa on the voltage measured on the other mesa is detected. Both effects can be explained by charge-imbalance on the superconducting layers produced by the quasi-particle current, and can be described successfully by a recently developed theory of nonequilibrium effects in intrinsic Josephson systems.Comment: 8pages, 9figures, submitted to Phys. Rev.

2,4,6-Triamino-1,3,5-triazine-1,3-diium aqua­penta­fluoridoaluminate

The title compound, (C3H8N6)[AlF5(H2O)], was obtained by solvothermal synthesis from the reaction of aluminium hydroxide, 1,3,5-triazine-2,4,6-triamine (melamine), aqueous HF and water at 323 K for 48 h. The structure consists of [AlF5(H2O)]2− octa­hedra and diprotonated melaminium cations. Cohesion is ensured by a three-dimensional network of hydrogen bonds

Xtru3D: Single-View 3D Object Reconstruction from Color and Depth Data

D object reconstruction from single image has been a noticeable research trend in recent years. The most common method is to rely on symmetries of real-life objects, but these are hard to compute in practice. However, a large class of everyday objects, especially when manufactured, can be generated by extruding a 2D shape through an extrusion axis. This paper proposes to exploit this property to acquire 3D object models using a single RGB+Depth image, such as those provided by available low-cost range cameras. It estimates the hidden parts by exploiting the geometrical properties of everyday objects, and both depth and color information are combined to refine the model of the object of interest. Experimental results on a set of 12 common objects are shown to demonstrate not only the effectiveness and simplicity of our approach, but also its applicability for tasks such as robotic grasping.The research leading to these results has been funded by the HANDLE European project (FP7/2007-2013) under grant agreement ICT 231640-http://www.handle-project.eu.Publicad

Artificial-intelligence-driven scanning probe microscopy

Scanning probe microscopy (SPM) has revolutionized the fields of materials, nano-science, chemistry, and biology, by enabling mapping of surface properties and surface manipulation with atomic precision. However, these achievements require constant human supervision; fully automated SPM has not been accomplished yet. Here we demonstrate an artificial intelligence framework based on machine learning for autonomous SPM operation (DeepSPM). DeepSPM includes an algorithmic search of good sample regions, a convolutional neural network to assess the quality of acquired images, and a deep reinforcement learning agent to reliably condition the state of the probe. DeepSPM is able to acquire and classify data continuously in multi-day scanning tunneling microscopy experiments, managing the probe quality in response to varying experimental conditions. Our approach paves the way for advanced methods hardly feasible by human operation (e.g., large dataset acquisition and SPM-based nanolithography). DeepSPM can be generalized to most SPM techniques, with the source code publicly available