Compact High-Velocity Clouds at High Resolution

Six examples of the compact, isolated high-velocity clouds catalogued by Braun & Burton (1999) and identified with a dynamically cold ensemble of primitive objects falling towards the barycenter of the Local Group have been imaged with the Westerbork Synthesis Radio Telescope; an additional ten have been imaged with the Arecibo telescope. The imaging reveals a characteristic core/halo morphology: one or several cores of cool, relatively high-column-density material, are embedded in an extended halo of warmer, lower-density material. Several of the cores show kinematic gradients consistent with rotation; these CHVCs are evidently rotationally supported and dark-matter dominated. The imaging data allows several independent estimates of the distances to these objects, which lie in the range 0.3 to 1.0 Mpc. The CHVC properties resemble what might be expected from very dark dwarf irregular galaxies.Comment: 12 pages, 7 figures, to appear in "The Chemical Evolution of the Milky Way: Stars versus Clusters", eds. F. Matteuchi and F. Giovannelli, Kluwer Academic Publisher

Experimental realisation of Shor's quantum factoring algorithm using qubit recycling

Quantum computational algorithms exploit quantum mechanics to solve problems exponentially faster than the best classical algorithms. Shor's quantum algorithm for fast number factoring is a key example and the prime motivator in the international effort to realise a quantum computer. However, due to the substantial resource requirement, to date, there have been only four small-scale demonstrations. Here we address this resource demand and demonstrate a scalable version of Shor's algorithm in which the n qubit control register is replaced by a single qubit that is recycled n times: the total number of qubits is one third of that required in the standard protocol. Encoding the work register in higher-dimensional states, we implement a two-photon compiled algorithm to factor N=21. The algorithmic output is distinguishable from noise, in contrast to previous demonstrations. These results point to larger-scale implementations of Shor's algorithm by harnessing scalable resource reductions applicable to all physical architectures.Comment: 7 pages, 3 figure

Comparison of Sentiment Analysis and User Ratings in Venue Recommendation

Venue recommendation aims to provide users with venues to visit, taking into account historical visits to venues. Many venue recommendation approaches make use of the provided users’ ratings to elicit the users’ preferences on the venues when making recommendations. In fact, many also consider the users’ ratings as the ground truth for assessing their recommendation performance. However, users are often reported to exhibit inconsistent rating behaviour, leading to less accurate preferences information being collected for the recommendation task. To alleviate this problem, we consider instead the use of the sentiment information collected from comments posted by the users on the venues as a surrogate to the users’ ratings. We experiment with various sentiment analysis classifiers, including the recent neural networks-based sentiment analysers, to examine the effectiveness of replacing users’ ratings with sentiment information. We integrate the sentiment information into the widely used matrix factorization and GeoSoCa multi feature-based venue recommendation models, thereby replacing the users’ ratings with the obtained sentiment scores. Our results, using three Yelp Challenge-based datasets, show that it is indeed possible to effectively replace users’ ratings with sentiment scores when state-of-the-art sentiment classifiers are used. Our findings show that the sentiment scores can provide accurate user preferences information, thereby increasing the prediction accuracy. In addition, our results suggest that a simple binary rating with ‘like’ and ‘dislike’ is a sufficient substitute of the current used multi-rating scales for venue recommendation in location-based social networks

Integrative analyses identify modulators of response to neoadjuvant aromatase inhibitors in patients with early breast cancer

Introduction Aromatase inhibitors (AIs) are a vital component of estrogen receptor positive (ER+) breast cancer treatment. De novo and acquired resistance, however, is common. The aims of this study were to relate patterns of copy number aberrations to molecular and proliferative response to AIs, to study differences in the patterns of copy number aberrations between breast cancer samples pre- and post-AI neoadjuvant therapy, and to identify putative biomarkers for resistance to neoadjuvant AI therapy using an integrative analysis approach. Methods Samples from 84 patients derived from two neoadjuvant AI therapy trials were subjected to copy number profiling by microarray-based comparative genomic hybridisation (aCGH, n = 84), gene expression profiling (n = 47), matched pre- and post-AI aCGH (n = 19 pairs) and Ki67-based AI-response analysis (n = 39). Results Integrative analysis of these datasets identified a set of nine genes that, when amplified, were associated with a poor response to AIs, and were significantly overexpressed when amplified, including CHKA, LRP5 and SAPS3. Functional validation in vitro, using cell lines with and without amplification of these genes (SUM44, MDA-MB134-VI, T47D and MCF7) and a model of acquired AI-resistance (MCF7-LTED) identified CHKA as a gene that when amplified modulates estrogen receptor (ER)-driven proliferation, ER/estrogen response element (ERE) transactivation, expression of ER-regulated genes and phosphorylation of V-AKT murine thymoma viral oncogene homolog 1 (AKT1). Conclusions These data provide a rationale for investigation of the role of CHKA in further models of de novo and acquired resistance to AIs, and provide proof of concept that integrative genomic analyses can identify biologically relevant modulators of AI response

Dynamical Boson Stars

The idea of stable, localized bundles of energy has strong appeal as a model for particles. In the 1950s John Wheeler envisioned such bundles as smooth configurations of electromagnetic energy that he called {\em geons}, but none were found. Instead, particle-like solutions were found in the late 1960s with the addition of a scalar field, and these were given the name {\em boson stars}. Since then, boson stars find use in a wide variety of models as sources of dark matter, as black hole mimickers, in simple models of binary systems, and as a tool in finding black holes in higher dimensions with only a single killing vector. We discuss important varieties of boson stars, their dynamic properties, and some of their uses, concentrating on recent efforts.Comment: 79 pages, 25 figures, invited review for Living Reviews in Relativity; major revision in 201

Histone H2A (H2A.X and H2A.Z) Variants in Molluscs: Molecular Characterization and Potential Implications For Chromatin Dynamics

Histone variants are used by the cell to build specialized nucleosomes, replacing canonical histones and generating functionally specialized chromatin domains. Among many other processes, the specialization imparted by histone H2A (H2A.X and H2A.Z) variants to the nucleosome core particle constitutes the earliest response to DNA damage in the cell. Consequently, chromatin-based genotoxicity tests have been developed in those cases where enough information pertaining chromatin structure and dynamics is available (i.e., human and mouse). However, detailed chromatin knowledge is almost absent in most organisms, specially protostome animals. Molluscs (which represent sentinel organisms for the study of pollution) are not an exception to this lack of knowledge. In the present work we first identified the existence of functionally differentiated histone H2A.X and H2A.Z variants in the mussel Mytilus galloprovincialis (MgH2A.X and MgH2A.Z), a marine organism widely used in biomonitoring programs. Our results support the functional specialization of these variants based on: a) their active expression in different tissues, as revealed by the isolation of native MgH2A.X and MgH2A.Z proteins in gonad and hepatopancreas; b) the evolutionary conservation of different residues encompassing functional relevance; and c) their ability to confer specialization to nucleosomes, as revealed by nucleosome reconstitution experiments using recombinant MgH2A.X and MgH2A.Z histones. Given the seminal role of these variants in maintaining genomic integrity and regulating gene expression, their preliminary characterization opens up new potential applications for the future development of chromatin-based genotoxicity tests in pollution biomonitoring programs