X-ray haloes and star formation in early-type galaxies

High resolution 2D hydrodynamical simulations describing the evolution of the hot ISM in axisymmetric two-component models of early-type galaxies well reproduced the observed trends of the X-ray luminosity ($L_\mathrm{x}$) and temperature ($T_\mathrm{x}$) with galaxy shape and rotation, however they also revealed the formation of an exceedingly massive cooled gas disc in rotating systems. In a follow-up of this study, here we investigate the effects of star formation in the disc, including the consequent injection of mass, momentum and energy in the pre-existing interstellar medium. It is found that subsequent generations of stars originate one after the other in the equatorial region; the mean age of the new stars is $> 5$ Gyr, and the adopted recipe for star formation can reproduce the empirical Kennicutt-Schmidt relation. The results of the previous investigation without star formation, concerning $L_\mathrm{x}$ and $T_\mathrm{x}$ of the hot gas, and their trends with galactic shape and rotation, are confirmed. At the same time, the consumption of most of the cold gas disc into new stars leads to more realistic final systems, whose cold gas mass and star formation rate agree well with those observed in the local universe. In particular, our models could explain the observation of kinematically aligned gas in massive, fast-rotating early-type galaxies.Comment: 20 pages, 10 figures, 5 tables. Accepted for publication in MNRA

The effects of stellar dynamics on the X-ray emission of flat early-type galaxies

Observational and numerical studies gave hints that the hot gaseous haloes of ETGs may be sensitive to the galaxy internal kinematics. By using high resolution 2D hydro simulations, and realistic two-component (stars plus dark matter) axisymmetric galaxy models, we study the evolution of the hot haloes in a suite of flat ETGs of fixed mass distribution, but with variable amounts of azimuthal velocity dispersion and rotational support, including the possibility of a counter-rotating inner stellar disc. The hot halo is fed by stellar mass losses and heated by SNIa explosions and thermalization of stellar motions. We measure the value of the thermalization parameter gamma (the ratio between the heating due to the relative velocity between the stellar streaming and the ISM bulk flow, and the heating attainable by complete thermalization of the stellar streaming motions). We find that 1) the X-ray emission and the average temperature are larger in fully velocity dispersion supported systems; 2) 0.1<gamma<0.2 for isotropic rotators (with a trend for being larger for lower dark mass models); 3) systems that are isotropic rotators at large radii with an inner counter-rotating disc, or fully velocity dispersion supported systems with an inner rotating disc, have gamma=1, again with a trend to increase for lower dark mass contents. We also find that the lower X-ray luminosities of isotropic rotators cannot be explained just by their low gamma, but are due to the complicated flow structure, consequence of the angular momentum stored at large radii. X-ray emission weighted temperatures and luminosities nicely match observed values; the X-ray isophotes are boxy in case of significant galaxy rotation. Overall, it is found that rotation has an important role to explain the observational result that more rotationally supported ETGs on average show a lower X-ray emission [abridged].Comment: 22 pages, 13 figures, accepted for publication in MNRAS. Comments welcom

Disk dynamics and the X-ray emission of S0 and flat early-type galaxies

With 2D hydrodynamical simulations, we study the evolution of the hot gas flows in early-type galaxies, focussing on the effects of galaxy rotation on the thermal and dynamical status of the ISM. The galaxy is modelled as a two-component axisymmetric system (stars and dark matter), with a variable amount of azimuthal velocity dispersion and rotational support; the presence of a counter rotating stellar disk is also considered. It is found that the ISM of the rotationally supported (isotropic) model is more prone to thermal instabilities than the fully velocity dispersion counterpart, while its ISM temperature and X-ray luminosity are lower. The model with counter rotation shows an intermediate behaviour.Comment: 2 pages, 2 figures. Proceedings of the International Conference "X-ray Astronomy: towards the next 50 years!", Milan, 1-5 Oct 201

AFM Dissipation Topography of Soliton Superstructures in Adsorbed Overlayers

In the atomic force microscope, the nanoscale force topography of even complex surface superstructures is extracted by the changing vibration frequency of a scanning tip. An alternative dissipation topography with similar or even better contrast has been demonstrated recently by mapping the (x,y)-dependent tip damping but the detailed damping mechanism is still unknown. Here we identify two different tip dissipation mechanisms: local mechanical softness and hysteresis. Motivated by recent data, we describe both of them in a onedimensional model of Moire' superstructures of incommensurate overlayers. Local softness at "soliton" defects yields a dissipation contrast that can be much larger than the corresponding density or corrugation contrast. At realistically low vibration frequencies, however, a much stronger and more effective dissipation is caused by the tip-induced nonlinear jumping of the soliton, naturally developing bistability and hysteresis. Signatures of this mechanism are proposed for experimental identification.Comment: 5 pages, 5 figures, Phys Rev B 81, 045417 (2010

WE DON’T NEED NO EDUCATION : REQUIRED ABILITIES IN ONLINE LABOR MARKETS

The paper presents a study conducted through a cross sectional research design and a quantitative content analysis method to categorize and provide a numerically based summary of the different abilities requested in online routine labor markets like Mechanical Turk. These markets are growing nowadays for the outsourcing of routine information processing tasks. This is mainly due to the existence of tasks that computerization is not capable to substitute. This research is a first attempt to study abilities required by employers from low skilled information processing workers in virtual marketplaces. It also points out the fact that a new generation of temporary workers is appearing on the labor market raising questions about their characteristics, behaviors and differences compared to high skilled knowledge workers. The unit of analysis is a sample of tasks published by requesters on Mechanical Turk starting from 24th to 31th January 2010

Tackling Age-Invariant Face Recognition with Non-Linear PLDA and Pairwise SVM

Face recognition approaches, especially those based on deep learning models, are becoming increasingly attractive for missing person identification, due to their effectiveness and the relative simplicity of obtaining information available for comparison. However, these methods still suffer from large accuracy drops when they have to tackle cross-age recognition, which is the most common condition to face in this specific task. To address these challenges, in this paper we investigate the contribution of different generative and discriminative models that extend the Probabilistic Linear Discriminant Analysis (PLDA) approach. These models aim at disentangling identity from other facial variations (including those due to age effects). As such, they can improve the age invariance characteristics of state-of-the-art deep facial embeddings. In this work, we experiment with a standard PLDA, a non-linear version of PLDA, the Pairwise Support Vector Machine (PSVM), and introduce a nonlinear version of PSVM (NL--PSVM) as a novelty. We thoroughly analyze the proposed models' performance when addressing cross-age recognition in a large and challenging experimental dataset containing around 2.5 million images of 790,000 individuals. Results on this testbed confirm the challenges in age invariant face recognition, showing significant differences in the effects of aging across embedding models, genders, age ranges, and age gaps. Our experiments show as well the effectiveness of both PLDA and its proposed extensions in reducing the age sensitivity of the facial features, especially when there are significant age differences (more than ten years) between the compared images or when age-related facial changes are more pronounced, such as during the transition from childhood to adolescence or from adolescence to adulthood. Further experiments on three standard cross-age benchmarks (MORPH2, CACD-VS and FG-NET) confirm the proposed models' effectiveness

Sviluppo di un algoritmo per la proposta di stoccaggio

L’obiettivo della tesi è quello di realizzare una nuova versione di un algoritmo per la proposta di stoccaggio, partendo dall’analisi del problema e del suo contesto, per poi passarne alla progettazione e all’implementazione. Viene effettuata un'introduzione al contesto del problema (logiche di magazzino, WMS e stoccaggio), e poi vengono effettuate le fasi di analisi, progettazione e implementazione del codice. Per ogni funzionalità implementata vengono mostrate le User Stories che la descrivono (analisi), lo pseudo-codice scritto (progettazione), e il relativo codice C# (implementazione)

Reproducibility is Nothing without Correctness: The Importance of Testing Code in NLP

Despite its pivotal role in research experiments, code correctness is often presumed only on the basis of the perceived quality of the results. This comes with the risk of erroneous outcomes and potentially misleading findings. To address this issue, we posit that the current focus on result reproducibility should go hand in hand with the emphasis on coding best practices. We bolster our call to the NLP community by presenting a case study, in which we identify (and correct) three bugs in widely used open-source implementations of the state-of-the-art Conformer architecture. Through comparative experiments on automatic speech recognition and translation in various language settings, we demonstrate that the existence of bugs does not prevent the achievement of good and reproducible results and can lead to incorrect conclusions that potentially misguide future research. In response to this, this study is a call to action toward the adoption of coding best practices aimed at fostering correctness and improving the quality of the developed software

Genome-Wide Association Study Reveals Candidate Genes for Flowering Time Variation in Common Bean (Phaseolus vulgaris L.)

The common bean is one of the most important staples in many areas of the world. Extensive phenotypic and genetic characterization of unexplored bean germplasm are still needed to unlock the breeding potential of this crop. Dissecting genetic control of flowering time is of pivotal importance to foster common bean breeding and to develop new varieties able to adapt to changing climatic conditions. Indeed, flowering time strongly affects yield and plant adaptation ability. The aim of this study was to investigate the genetic control of days to flowering using a whole genome association approach on a panel of 192 highly homozygous common bean genotypes purposely developed from landraces using Single Seed Descent. The phenotypic characterization was carried out at two experimental sites throughout two growing seasons, using a randomized partially replicated experimental design. The same plant material was genotyped using double digest Restriction-site Associated DNA sequencing producing, after a strict quality control, a dataset of about 50 k Single Nucleotide Polymorphisms (SNPs). The Genome-Wide Association Study revealed significant and meaningful associations between days to flowering and several SNP markers; seven genes are proposed as the best candidates to explain the detected associations