From Giants to Dwarfs: Probing the Edges of Galaxies

In this thesis we address fundamental questions about what constitutes and limits an HI disc, probing the distribution of neutral gas in the outer parts of galaxies. We use a subsample of galaxies observed as part of the THINGS survey to investigate the HI extent of spiral galaxy discs. We revisit previous work on the extent of HI discs, showing the limitations set by insufficient linear resolution. We then exploit the high spatial and velocity resolution combined with good sensitivity of THINGS to investigate where the atomic gas discs end and what might shape their edges. We find that the atomic gas surface density across most of the disc is constant at 5 – 10 x 10^20 atoms/cm^2 and drops sharply at large radius. The general shape of the HI distribution is well described by a Sérsic-type function with a slope index, n = 0.14 - 0.22 and characteristic radius ri. We propose a new column density threshold of 5 x 10^19 atoms/cm^2 to define the extent of the gas disc. This limit is well within reach of modern instruments and is at the level where disc gas becomes susceptible to ionisation by an extragalactic radiation field. We argue that at this level the HI column density has decreased to one tenth of that across the inner disc and that by going to yet lower column density the disc is unlikely to grow by more than 10% in radius. The HI column density at which the radial profiles turn over is too high for it to be caused by ionisation by an extragalactic UV field and we postulate that the HI extent is set by how galaxy discs form. Ionisation by extragalactic radiation will only play a rôle at column densities below 5 x 10^19 atoms/cm^2, if any. To study the crucial relation between observed edges and how closely these reproduce the intrinsic distribution of gas through our interferometric measurements, we created an ensemble of models based on four radial density distributions. We conclude that the observed edges in spiral galaxies faithfully reflect their intrinsic shape. Only in very specific cases of highly inclined (>75º) and/or large vertical scaleheight discs do we see strong deviations from the intrinsic surface density of the observed shape of the edges in spiral galaxies. In the case of NGC 3198 we concluded that there is no significant difference in the radial profiles obtained with either constant or exponentially increasing vertical gas distributions, when scaleheights are not higher than 1 kpc at the outskirts of the disc. We infer an upper limit to the scaleheight of NGC 3198 of 2 kpc. To address the distribution of neutral gas at larger scales, we study an HI rich, giant LSB galaxy, NGC 765. We present HI spectral line and radio-continuum VLA data, complemented by optical and Chandra X-ray maps. NGC 765 has the largest HI-to-optical ratio known to date of any spiral galaxy and one of the largest known HI discs in absolute size with a diameter of ~ 240 kpc measured at a surface density of 2 x 10^19 atoms/cm^2. We derive a total HI mass of M_HI = 4.7 x 10^10 M_sun, a dynamical mass of M_dyn = 5.1 x 10^11 M_sun and an HI mass to luminosity ratio of M_HI/L_B = 1.6, making it the nearest and largest “crouching giant”. Optical images reveal evidence of a central bar with tightly wound low-surface brightness spiral arms extending from it. Radio-continuum (L_1.4 GHz = 1.3 x 10^21 W/Hz) and X-ray (L_x ~ 1.7 x 10^40 erg/s) emission is found to coincide with the optical core of the galaxy, compatible with nuclear activity powered by a low-luminosity AGN. We may be dealing with a galaxy that has retained in its current morphology traces of its formation history. In fact, it may still be undergoing some accretion, as evidenced by the presence of HI clumps the size (< 10 kpc) and mass (10^8 -10^9 M_sun) of small (dIrr) galaxies in the outskirts of its HI disc and by the presence of two similarly sized companions. In an exploration of future work, we engaged in a study of the edges in the HI discs of dwarf irregular galaxies, their parameterisation and simulation. A collection of simulations were created based on the dwarf galaxy NGC 2366, similar to what was done for the larger spiral galaxies, showing that line-of-sight column densities are affected for discs with inclinations higher than 60º. Five out of eleven of the dwarfs from THINGS which are less inclined than 60º were analysed and parameterised with our Sérsic-type function. Their discs have average central column densities spread evenly from log_10 NHI = 20.7 atoms/cm^2 to log_10 NHI =21.3 atoms/cm^2. Their radial decline is shallower (slope index peaks around n ~ 0.3) than for spirals. The up-coming Local Irregular That Trace Local Extremes (LITTLE) THINGS project, will likely enlarge the number of local dwarf irregular (dIm) galaxies to which this type of analysis can be applied and for which these preliminary results verified

Multisensor Out Of Sequence Data Fusion for Estimating the State of Discrete Control Systems

The fusion center of a complex control system estimates its state with the information provided by different sensors. Physically distributed sensors, communication networks, pre-processing algorithms, multitasking, etc, introduce non-systematic delays in the arrival of information to the fusion center, making the information available out-of-sequence (OOS). For real-time control systems, the state has to be efficiently estimated with all the information received so far. So, several solutions of the OOS problem for dynamic multiple-input multiple-output (MIMO) discrete control systems traditionally solved by the Kalman filter (KF) have been proposed recently. This paper presents two new streamlined algorithms for the linear and non-linear case. IFAsyn, the linear algorithm, is equivalent to other optimal solutions but more general, efficient and easy to implement. EIFAsyn, the nonlinear one, is a new solution of the OOS problem in the extended KF (EKF) framework

National Eclipse Weather Experiment use and evaluation of a citizen science tool for schools outreach

The National Eclipse Weather Experiment (NEWEx) was a citizen science project for atmospheric data collection from the partial solar eclipse of 20th March 2015. Its role as a tool for schools’ outreach is discussed here, in seeking to bridge the gap between self-identification with the role of a scientist and engagement with science, technology, engineering and maths (STEM) subjects. (The science data generated has had other uses beyond this, explored elsewhere.) We describe the design of webforms for weather data collection, and the use of several external partners for the dissemination of the project nationwide. We estimate that up to 3500 pupils and teachers took part in this experiment, through the 127 schools’ postcodes identified in the data submission. Further analysis revealed that 43.3% of the schools were primary schools and 35.4% secondary. 96.3% of participants reported themselves as “captivated” or “inspired” by NEWEx. We also found that 60% of schools who took part in the experiment lie within the highest quintiles of engagement with higher education, which emphasises the need for the scientific community to be creative when using citizen science to target minority audiences

Minimizing the searching time of multiple targets in uncertain environments with multiple UAVs

The focus of this paper is the use of Unmanned Aerial Vehicles (UAVs) for searching multiple targets under uncertain conditions in the minimal possible time. The problem, known as Minimum Time Search (MTS), belongs to the Probabilistic Search (PS) field and addresses critical missions, such as search & rescue, and military surveillance. These operations, characterized by complex and uncertain environments, demand efficient UAV trajectory optimization. The multi-target version of PS introduces additional challenges, due to their higher complexity and the need to wisely distribute the UAV´s efforts among multiple targets. In order to tackle the under-explored multi-target aspect of MTS, we optimize the time to find all targets with new Ant Colony Optimization (ACO)-based planner. This novel optimization criterion is formulated using Bayes´ theory, considering probability models of the targets (initial belief and motion model) and the sensor likelihood. Our work contributes significantly by (i) developing an objective function tailored for multi-target MTS, (ii) proposing an ACO-based planner designed to effectively handle the complexities of multiple moving targets, and (iii) introducing a novel constructive heuristic that is used by the ACO-based planner, specifically designed for the multi-target MTS problem. The efficacy of our approach is demonstrated through comprehensive analysis and validation across various scenarios, showing superior performance over existing methods in complex multi-target MTS problems.This research work has been supported by the project Y2020/TCS-6420 of the Synergic program of the Comunidad Autonoma of Madrid, and by the Spanish national projects PID2021-127073OB-I00 and PID2021-127648OB-C33 of the MCIN/AEI/10.13039/501100011033/FEDER

The National Eclipse Weather Experiment: an assessment of citizen scientist weather observations

The National Eclipse Weather Experiment (NEWEx) was a citizen science project designed to assess the effects of the 20 March 2015 partial solar eclipse on the weather over the United Kingdom (UK). NEWEx had two principal objectives: to provide a spatial network of meteorological observations across the UK to aid the investigation of eclipse induced weather changes; and to develop a nationwide public engagement activity based participation of citizen scientists. In total NEWEx collected 15606 observations of air temperature, cloudiness, and wind speed and direction from 309 locations across the UK, over a 3 hour window spanning the eclipse period. The headline results were processed in near real-time, immediately published on-line, and featured in UK national press articles on the day of the eclipse. Here we describe the technical development of NEWEx and how the observations provided by the citizen scientists were analysed. By comparing the results of the NEWEx analyses with results from other investigations of the same eclipse using different observational networks, including measurements from the University of Reading’s Atmospheric Observatory, we demonstrate that NEWEx provided a fair representation of the change in the UK meteorological conditions throughout the eclipse. Despite the simplicity of the approach adopted, robust reductions in both temperature and wind speed during the eclipse were observed

Anàlisi del perfil del formador de formadors des de la perspectiva practicoreflexiva a les Illes Balears

academic plagiarism, cyberplagiarism, academic fraud, higher education, academic dishonesty, academic integrityLa finalitat de la recerca fou elaborar el mapa competencial del formador de formadors per tal d’optimitzar-ne el desenvolupament professional en el marc de les Illes Balears. D’acord amb això, la recerca va dedicar els seus recursos a identificar les qualitats personals i les competències de referència dels formadors de formadors. Per tal d’establir l’estat de la qüestió del tema d’estudi, a partir de la realització d’una anàlisi documental, es presenta la situació actual del concepte de competència, de formador practicoreflexiu i es fa una aproximació a les principals aportacions sobre les competències dels formadors. La recerca que presentam és de tipus qualitatiu i s’ha basat en la metodologia fenomenogràfica a partir de la realització de cinc grups de discussió, que comptaren amb la participació de trenta-tres informadors clau de diversos àmbits de la temàtica d’estudi. Per realitzar l’anàlisi interpretativa s’utilitzà el mètode de comparació constant, que va permetre classificar i analitzar la informació aportada pels experts. A partir d’aquesta informació es va establir un mapa de vuit qualitats personals i nou unitats de competència dels formadors de formadors, que dibuixen un professional amb un perfil d’acompanyament del procés de canvi i de reflexió sobre la seva pràctica. Aquest mapa competencial, sens dubte ha d’esdevenir un element clau per a la millora d’aquest professional a curt termini.The purpose of this research study was to develop a competency map of teacher trainers to maximise their professional development within the framework of the Balearic Islands. Accordingly, the study devoted its resources to identifying teacher trainers’ personal qualities and competencies of reference. To establish the state of the subject of study, the current status of the concept of competence and reflective-practical trainers is presented and the main input on the trainers’ skills are outlined on the basis of a documentary analysis. The present study is qualitative and based on the phenomenographic methodology using five discussion groups with the participation of thirty-three key informants from the various thematic areas of study. To conduct the interpretive analysis, the study used the Constant Comparative Method, which allowed the information provided by experts to be classified and analysed. This information was used to establish a map of eight personal qualities and nine units of competence for the teacher trainers that outlined a professional profile that accompanied the process of change and reflection on their practice. This competency map is undoubtedly a key element in improving professionals in the short term

Minimum time search in real-world scenarios using multiple UAVs with onboard orientable cameras

This paper proposes a new evolutionary planner to determine the trajectories of several Unmanned Aerial Vehicles (UAVs) and the scan direction of their cameras for minimizing the expected detection time of a nondeterministically moving target of uncertain initial location. To achieve this, the planner can reorient the UAVs cameras and modify the UAVs heading, speed, and height with the purpose of making the UAV reach and the camera observe faster the areas with high probability of target presence. Besides, the planner uses a digital elevation model of the search region to capture its influence on the camera likelihood (changing the footprint dimensions and the probability of detection) and to help the operator to construct the initial belief of target presence and target motion model. The planner also lets the operator include intelligence information in the initial target belief and motion model, in order to let him/her model real-world scenarios systematically. All these characteristics let the planner adapt the UAV trajectories and sensor poses to the requirements of minimum time search operations over real-world scenarios, as the results of the paper, obtained over 3 scenarios built with the modeling aid-tools of the planner, show.This work was supported by Airbus under SAVIER AER30459 projec

Unified fusion system based on bayesian networks for autonomous mobile robots

A multisensor fusion system that is usedfor estimating the location of a robot and the state of the objects around is presented. The whole fusion system has been implemented as a Dynamic Bayesian Networks (DBN) with the purpose of having a homogenous and formalized way of capturing the dependencies that exist between the robot location, the state of the environment, and all the sensorial data. At this stage of the research it consists of two independent DBNs, one for estimating the robot location and another for building an occupancy probabilistic map of the environment, which are the basis of a unified fusion system. The dependencies of the variables and information in the two DBN will be captured by a unique DBN constructed by adding arcs (and nodes if necessary) between the two DBN. The DBN implemented so far can be used in robots with different sets of sensors

Study of animal remains dug out during the excavations of a Nuragic village in Sardinia

This paper presents the results of the zooarchaeological analysis of the faunal materials brought to light during the excavations set up in the Nuragic village surrounding the Santu Antine Nuraghe, near Torralba (Sassari), Sardinia. Precisely, the remains come from the structure of the village named by archaeologists hut 12. They are 779 specimens out of thousands animal remains from the whole archaeological site. The majority of the rests belong to sheep (Ovis aries) or goats (Capra hircus), cattle (Bos taurus), pigs (Sus scrofa) and deers (Cervus elaphus). Such material may provide suggestions about the productive use of animals in the village and point out the importance of the economical management of animals in the Nuragic society. Indeed, many remains show signs with human origin, which testify that the hut may have been a workplace where bone fragments were processed to obtain different kind of tools

ART-GCS: an adaptive real-time multi-agent ground control station

Ground Control Stations (GCS) are essential tools to monitor and command real-world complex missions involving Unmanned Vehicles (UVs). As the number and types of UVs in the mission grows, implementing a robust and adaptable GCS, capable of simplifying and reducing operator' interactions and mental workloads, becomes an engineering challenge. To address it, this paper presents a new Adaptive-Real-Time (ART)-GCS that 1) allows to monitor and control a runtime changing number of heterogeneous UVs, 2) adapt its GUI to the mission requirements and operators workload to minimize their fatigue and stress, and 3) provide support to experiments with actual and simulated UVs. To show its benefits in real-world missions, this paper presents a field experiment where, for safety reasons, a simulated unmanned aerial vehicle has to find an oil-spill that must be enclosed by a containment boom dragged by two real unmanned surface vehicles