La búsqueda de hielo de agua en Cometas y Asteroides

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Físicas, Departamento de Física de la Tierra y Astrofísica, leída el 12/02/2021. Tesis formato europeo (compendio de artículos)The presence of water is considered one of the key ingredients for the formation of life on Earth. Indeed, current theories as to the origin of the Earth’s oceans suggest that the water located there originated from both comets and asteroids, with the exact fractional contribution still under discussion. However, water is not unique to the Earth; it has been found hidden deep inside polar craters on the moon, as well as in its fragment OH form contained in moon regolith. It is believed to make up over two thirds of the mass of the giant icy planets Uranus and Neptune. It is prevalent in the form of ice throughout the outer solar system on the moons of planets, on Kuiper Belt Objects, and on comets. In the case of asteroids, although few detections of surface ice have been made, evidence of hydrated minerals (any mineral containing H2O or OH) abound. A search for water ice on the surface and subsurface of comets and asteroids provides not only key information as to its presence and distribution on these primitive bodies, it also contributes to giving a deeper understanding on how the solar system formed, how water was delivered to the Earth by these bodies, and indeed how life emerged as a result. This thesis has as its main goal to search for the presence of water ice on and just below the surfaces of comets and asteroids, estimating its coverage and where feasible characterising its properties. This goal is broken down into two objectives, whereby we search for and characterise ice found on cometary (1st objective) and asteroid (2nd objective) surfaces and subsurfaces. In this thesis, we present a number of publications aiming to address these objectives...La presencia de agua se considera uno de los ingredientes clave para la formación de vida en la Tierra. De hecho, las teorías actuales sobre el origen de los océanos de la Tierra sugieren que el agua que se encuentra allí se originó tanto en cometas como en asteroides, con la contribución fraccionaria exacta aún en discusión. Sin embargo, el agua no es exclusiva de la Tierra; se ha encontrado escondido en el interior de los cráteres polares de la luna, así como en su forma de fragmento OH contenido en su regolito. Se cree que constituye más de dos tercios de la masa de los planetas helados gigantes Urano y Neptuno. Prevalece en forma de hielo en todo el sistema solar exterior en las lunas de los planetas, en los objetos del cinturón de Kuiper y en los cometas. En el caso de los asteroides, aunque se han realizado pocas detecciones de hielo en la superficie, abunda la evidencia de minerales hidratados (cualquier mineral que contenga H2O u OH). La búsqueda de hielo de agua en la superficie y el sub-superficie de cometas y asteroides proporciona no solo información clave sobre su presencia y distribución en estos cuerpos primitivos, sino que también contribuye a brindar una comprensión más profunda de cómo se formó el sistema solar, cómo se entregó el agua a la Tierra por estos cuerpos y, de hecho, cómo surgió la vida como resultado. Esta tesis tiene como objetivo principal buscar la presencia de hielo de agua sobre y justo debajo de las superficies de cometas y asteroides, estimando su cobertura y, cuando sea posible, caracterizando sus propiedades. Este objetivo principal se divide en dos objetivos específicos, mediante los cuales buscamos y caracterizamos el hielo que se encuentra en los superficies y sub-superficies de cometas (primer objetivo) y asteroides (segundo objetivo). En esta tesis presentamos una serie de publicaciones destinadas a abordar estos objetivos...Fac. de Ciencias FísicasTRUEunpu

Core Values: American Ambivalence Towards Equality, Limited Government and Moral Traditionalism

This dissertation examines the role of core values in American public opinion, utilizing the closed-ended questions used to measure values in the National Election Studies (NES) survey. In-depth interviews were conducted with a non-random sample of 31 individuals recruited in the Washington D.C. area and in Rockingham County Virginia. These respondents were first asked to answer the NES value questions and then to elaborate on their detailed thoughts generated by answering these questions on limited government, equality and moral traditionalism. The results of this cognitive interviewing on how individuals interpret these widely used measures of values should be useful to researchers wishing to gain a better understanding of the sources of instability and error in these NES measures. In addition, quantitative analyses of NES data for the years between 1992 and 2004 were used to provide further insights from the in-depth interviews. The results of this research contribute to the broader political science literature on values. While the public is often uninformed about many issues of politics and policy, Feldman and other scholars have argued that values can serve to anchor public beliefs. By using values, the public is presumably able to take information shortcuts to substantive political decision making. Values are often conceptualized as stable and durable beliefs that can affect many specific attitudes. This study finds substantial public ambivalence towards limited government, equality and moral traditionalism. While some scholars, like Alvarez and Brehm, have argued that ambivalence is rare, this study finds that the public is torn about many of their core values. Ambivalence towards core values is often caused by feelings about specific social groups and social contexts. Conflicts between values and the different dimensions of each value also were a source of conflict for many of these respondents. The organization of the public's values into value systems thus appears weak. In some cases partisanship provides some of the glue that links different values together. These findings are important because they illustrate the complexity of the public's values. The public may hold a number of core values, but this study shows these beliefs to be intricate, nuanced and conflicted

The water regime of dwarf planet (1) Ceres

The traditional view of minor bodies in the (inner) Solar System is that they are split into icy comets and rocky asteroids. However this has been challenged by recent results, such as the discovery of comets on asteroidal orbits in the outer asteroid belt (between Mars and Jupiter) and the detection of water ice frost on the surface of asteroid (24) Themis. The discovery of water ice on the surface of asteroids has profound implications for how the Solar System formed, and challenges our ideas about the stability of ice in the inner Solar System. The study of volatiles in the asteroid belt places strong constraints on the temperature and composition distribution in the proto-planetary disk,and on possible sources of terrestrial water, and strongly constrains formation models of the early Solar System

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

The IDENTIFY study: the investigation and detection of urological neoplasia in patients referred with suspected urinary tract cancer - a multicentre observational study

Objective To evaluate the contemporary prevalence of urinary tract cancer (bladder cancer, upper tract urothelial cancer [UTUC] and renal cancer) in patients referred to secondary care with haematuria, adjusted for established patient risk markers and geographical variation. Patients and Methods This was an international multicentre prospective observational study. We included patients aged ≥16 years, referred to secondary care with suspected urinary tract cancer. Patients with a known or previous urological malignancy were excluded. We estimated the prevalence of bladder cancer, UTUC, renal cancer and prostate cancer; stratified by age, type of haematuria, sex, and smoking. We used a multivariable mixed-effects logistic regression to adjust cancer prevalence for age, type of haematuria, sex, smoking, hospitals, and countries. Results Of the 11 059 patients assessed for eligibility, 10 896 were included from 110 hospitals across 26 countries. The overall adjusted cancer prevalence (n = 2257) was 28.2% (95% confidence interval [CI] 22.3–34.1), bladder cancer (n = 1951) 24.7% (95% CI 19.1–30.2), UTUC (n = 128) 1.14% (95% CI 0.77–1.52), renal cancer (n = 107) 1.05% (95% CI 0.80–1.29), and prostate cancer (n = 124) 1.75% (95% CI 1.32–2.18). The odds ratios for patient risk markers in the model for all cancers were: age 1.04 (95% CI 1.03–1.05; P < 0.001), visible haematuria 3.47 (95% CI 2.90–4.15; P < 0.001), male sex 1.30 (95% CI 1.14–1.50; P < 0.001), and smoking 2.70 (95% CI 2.30–3.18; P < 0.001). Conclusions A better understanding of cancer prevalence across an international population is required to inform clinical guidelines. We are the first to report urinary tract cancer prevalence across an international population in patients referred to secondary care, adjusted for patient risk markers and geographical variation. Bladder cancer was the most prevalent disease. Visible haematuria was the strongest predictor for urinary tract cancer