263,100 research outputs found
A new method to identify subclasses among AGB stars using Gaia and 2MASS photometry
No full textAims. We explore the wealth of high-quality photometric data provided by data release 2 (DR2) of the Gaia mission for long-period variables (LPVs) in the Large Magellanic Cloud (LMC). Our goal is to identify stars of various types and masses along the asymptotic giant branch. Methods. For this endeavour, we developed a new multi-band approach combining Wesenheit functions WRP,BP−RP and WKs,J−Ks in the Gaia BP, RP, and 2MASS J, Ks spectral ranges, respectively, and use a new diagram, (WRP,BP−RP − WKs,J−Ks) versus Ks, to distinguish between different kinds of stars in our sample of LPVs. We used stellar population synthesis models to validate our approach. Results. We demonstrate the ability of the new diagram to discriminate between O- and C-rich objects, and to identify low-mass, intermediate-mass, and massive O-rich red giants, as well as extreme C-rich stars. Stellar evolution and population synthesis models guide the interpretation of the results, highlighting the diagnostic power of the new tool to discriminate between stellar initial masses, chemical properties, and evolutionary stages
Cultural differences and social amplification of risk of a tourism destination: foreign media coverage after 2016/2017 earthquakes in Central Italy
No full textLe destinazioni turistiche sono molto esposte ai disastri che possono influenzare le richieste e le tendenze del turismo. Infatti, le attività terroristiche, l'instabilità politica e i disastri naturali sono i tre fattori principali, nella società contemporanea, che possono influenzare e sostenere la percezione del rischio e quindi, avere un impatto sul processo decisionale del turista. Questa percezione e l'amplificazione sociale del rischio sono influenzate dalla copertura mediatica durante gli eventi. Lo scopo del presente studio è quello di indagare il ruolo della copertura mediatica nella segnalazione del rischio nel contesto di una "destinazione a rischio", come nel caso della regione Marche, che è stata colpita da diversi eventi sismici nei mesi di agosto e ottobre 2016 e nel gennaio 2017. In particolare, questo studio analizza le differenze culturali dal punto di vista della copertura mediatica dei giornali online nei due paesi durante il periodo dei terremoti utilizzando un approccio esplorativo. Questo studio richiama l'attenzione sulle differenze culturali nella copertura mediatica e nell'amplificazione sociale del rischio Italia come area a rischio e potrebbe sensibilizzare i marketer del turismo e i politici sull'importanza della promozione personalizzata e delle strategie pubblicitarie considerando le differenze culturali.Tourism destinations are very exposed to disasters that can influence tourism demands and trends. As a matter of fact, terrorist activities, political instability and natural disasters are the three main factors, in the contemporary society, which can influence and support the risk perception and thus, have an impact on the tourist decision-making process. This perception and the social amplification of risk are affected by the media coverage during the events. The purpose of the current study is to investigate the role of media coverage in reporting risk in the context of a “risky destination”, as in the case of the Marche region, which has been stricken by several seismic events in August and October 2016 as well as in January 2017. In particular, this study analyses cultural differences from the perspective of online newspapers media coverage in the two countries during the earthquakes period using an explorative approach. This study draws attention to the cultural differences in media coverage and social amplification of risk in Italy as a risky area and could will raise awareness among tourism marketers and policymakers about the importance of customized promotion and advertising strategies considering cultural differences
Data Release 3
No full textContext. The third Gaia Data Release covers 34 months of data and includes the second Gaia catalogue of long-period variables (LPVs), with G variability amplitudes larger than 0.1 mag (5–95% quantile range).
Aims. The paper describes the production and content of the second Gaia catalogue of LPVs and the methods we used to compute the published variability parameters and identify C-star candidates.
Methods. We applied various filtering criteria to minimise contamination from variable star types other than LPVs. The period and amplitude of the detected variability were derived from model fits to the G-band light curve wherever possible. C stars were identified using their molecular signature in the low-resolution RP spectra.
Results. The catalogue contains 1 720 558 LPV candidates, including 392 240 stars with published periods (ranging from 35 to ∼1000 days) and 546 468 stars classified as C-star candidates. Comparison with literature data (OGLE and ASAS-SN) leads to an estimated completeness of 80%. The recovery rate is about 90% for the most regular stars (typically miras) and 60% for SRVs and irregular stars. At the same time, the number of known LPVs is increased by a factor of 6 with respect to literature data for amplitudes larger than 0.1 mag in G, and the contamination is estimated to be below 2%. Our C-star classification, based on solid theoretical arguments, is consistent with spectroscopically identified C stars in the literature. Caution must be taken in crowded regions, however, where the signal-ro-noise ratio of the RP spectra can become very low, or if the source is reddened by some kind of extinction. The quality and potential of the catalogue are illustrated by presenting and discussing LPVs in the solar neighbourhood, in globular clusters, and in galaxies of the Local Group.
Conclusions. This is the largest all-sky LPVs catalogue to date. The photometric depth reaches G = 20 mag. This is a unique dataset for research into the late stages of stellar evolution
Curriculum innovation in the Arab world : community interpreting and translation
No full textThe term ‘community interpreting’ denominates a field of practice and study of increasing significance among modern multicultural societies and geographically mobile populations. As encapsulated by Pöchhacker (1999: 126–127), ‘community interpreting refers to interpreting in institutional settings of a given society in which public service providers and individual clients do not speak the same language … community interpreting facilitates communication within a social entity (society) that includes culturally different sub-groups’. According to Gouadec (2007: 35), ‘Community translation encompasses all translating (and interpreting) carried out to facilitate inter-community relations within a given country where diverse linguistic (and cultural) communities cohabit’. These definitions refer in very general terms to multilingual community situations requiring language services, yet community interpreting and translation have been associated with a few prominent host societies to large numbers of immigrants and refugees; these include Australia, Canada, Sweden, the UK and, since the 1990s, Southern Europe. The literature on community interpreting and translation (e.g. Barsky, 1996; Hale, 2007; Niska, 2002; Taibi, 2011; Wadensjö, 1998) abounds with references to migrants, refugees, and language minorities as the main clients of community interpreters and translators. This association between community language services and mainly European and North American immigration settings is solidly entrenched – as my own experience attests. During much of my time as a community interpreter and translator in Spain in the 1990s and, subsequently, as a lecturer in the field in Spain and Australia, I gave little thought to the situation of the same professional services in the Arab world. Nor am I alone in this: during a meeting held at a Saudi university in 2014 to discuss research and training in community interpreting and language services for pilgrims, a Saudi MP commented that this was the first he had heard of community interpreting and translation and noted the attendant need to recruit qualified professionals to guarantee quality services. Effectively, working with Arabic in dominant Spanish- or English-speaking cultures can foster a unidirectional view of Arabic speakers as consumers only, simply because in (for example) Europe and Australia they are usually migrants or refugees who need interpreters to communicate with/access mainstream public services. Yet this paradigm must clearly be inverted in many other parts of the world: in Arab countries it is Arabic speakers who provide the respective public services and, generally, speakers of other languages who use them
Physical principles and applications of digital breast tomosyinthesis
No full textThe lack of conspicuity is the ultimate limitation to breast cancer detection. This is particularly important in dense breasts where the overlying fibroglandular structures may either obscure or simulate disease. Advanced applications of digital mammography aim to increase lesion conspicuity by reducing the contribution of the so-called structure noise. Digital Breast Tomosynthesis (DBT) is one of the most promising among such advanced applications. Its main advantages are the improvement of the conspicuity of structures, the possibility of depth localisation, and the smaller dynamic range required for each reconstructed slice.
I will review the physical principles of DBT with a focus on the commercially available systems and their different technical characteristics
Position estimation for a mobile robot using monocular vision and odometry
No full textWe describe a localisation system for a robot moving in a known environment .
Unlike the currently used methods for industrial robots, our approach does not
require any beacons to be installed : the system uses odometry to estimate the
vehicle position continuously, and corrects this estimation when necessary by
identifying some objects of the environment through vision . These objects, used as
landmarks, were previously recorded in a data base .
The different parts of the system are presented particularly the way the uncertainty
on odometry is updated and how prior knowledge (position estimation and data
base) is employed to facilitate landmark identification. 7 cm on xy and I deg on
the heading is the typical precision obtained in term of localisation .Nous présentons un système de localisation pour un robot mobile évoluant dans un environnement connu. La méthode, contrairement à celles actuellement utilisées dans l'industrie, ne nécessite pas l'équipement du site en balises : la position du robot est estimée à chaque instant par odométrie, et recalée périodiquement en repérant, à l'aide d'une caméra mobile montée sur le véhicule, des objets de l'environnement jouant le rôle d'amer. Ces objets sont répertoriés dans une base de données constituée au préalable. Les différentes composantes du système sont présentées : nous montrons en particulier comment l'incertitude sur la position du robot évolue avec les erreurs d'odométrie, et comment les connaissances a priori (position estimée, base de données) sont mises à profit pour identifier les amers. La précision typiquement obtenue en matière de localisation est de 7 cm selon xy et 1 deg en cap
Tecnologia al selenio amorfo
No full textLa tecnologia al selenio amorfo (a-Se) è una vecchia conoscenza della mammografia poiché negli anni Settanta-Ottanta, il substrato utilizzato nella xeromammografia per creare l’immagine latente era costituito dal selenio amorfo.
La tecnica della xeroradiografia è stata poi abbandonata, principalmente per il complesso sistema di lettura dell’immagine che prevedeva l’uso di un toner; la
recente possibilità di una lettura elettronica del segnale radiografico ha permesso il ritorno in grande stile di questo materiale.
Il selenio amorfo è un materiale fotoconduttore, ovvero, in seguito all’interazione con i raggi X, si crea un elevato numero di coppie di ioni che possono essere raccolti sulle facce opposte della piastra di selenio applicando un opportuno campo elettrico. La capacità di guidare le cariche elettriche lungo la direzione dell’interazione ed evitare i ben noti effetti di defocalizzazione, comuni a tutti i
sistemi di rivelazione indiretta dei raggi X, rappresenta il punto di forza di questa tecnologia ed è stata largamente utilizzata anche a fini commerciali per dimostrare la superiorità del fotoconduttore su tutti gli altri sistemi che richiedono la conversione dei raggi X in fotoni luminosi. In realtà, per ottenere prestazioni elevate in termini di risoluzione spaziale, bisogna applicare un campo elettrico
molto intenso e ciò ha causato al costruttore non pochi problemi di stabilità e rumore elettronico. È bene ricordare subito che la qualità fisica dell’immagine radiografica dipende da tre parametri fra loro interdipendenti: contrasto, risoluzione spaziale e rumore. Ciò significa che la rivelabilità di lesioni di piccole dimensioni o a basso contrasto dipende anche dal livello di esposizione (e quindi dalla dose al paziente) e dalle caratteristiche di rumore del rivelatore stesso
Operationalizing the experience factory for effort estimation in agile processes
No full text[Background] The effort required to systematically collect historical data is not always allocable in agile processes and historical data management is usually delegated to the developers' experience, who need to remember previous project details. However, even if well trained, developers cannot precisely remember a huge number of details, resulting in wrong decisions being made during the development process. [Aims] The goal of this paper is to operationalize the Experience Factory in an agile way, i.e., defining a strategy for collecting historical project data using an agile approach. [Method] We provide a mechanism for understanding whether a measure must be collected or not, based on the Return on Invested Time (ROIT). In order to validate this approach, we instantiated the factory with an exploratory case study, comparing four projects that did not use our approach with one project that used it after 12 weeks out of 37 and two projects that used it from the beginning. [Results] The proposed approach helps developers to constantly improve their estimation accuracy with a very positive ROIT of the collected measure. [Conclusions] From this first experience, we can conclude that the Experience Factory can be applied effectively to agile processes, supporting developers in improving their performance and reducing potential decision mistakes
Functional size measures and effort estimation in agile development: A replicated study
No full textTo help developers during the Scrum planning poker, in our previous work we ran a case study on a Moonlight Scrum process to understand if it is possible to introduce functional size metrics to improve estimation accuracy and to measure the accuracy of expert-based estimation. The results of this original study showed that expert-based estimations are more accurate than those obtained by means of models, calculated with functional size measures. To validate the results and to extend them to plain Scrum processes, we replicated the original study twice, applying an exact replication to two plain Scrum development processes. The results of this replicated study show that the accuracy of the effort estimated by the developers is very accurate and higher than that obtained through functional size measures. In particular, SiFP and IFPUG Function Points, have low predictive power and are thus not help to improve the estimation accuracy in Scrum
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