Control de la exposición en fotografía digital

Nos proponemos investigar las particularidades de la exposición digital, observar la práctica de la fotografía digital profesional y proponer nuevas técnicas para el control expositivo. Se trata de una tesis con una vocación pragmática que quiere apuntar soluciones prácticas. Buena parte de la técnica y expresión fotográfica está relacionada con el control de la exposición. La exposición puede determinar en la imagen: el grado de resolución, las zonas con información de tono, las zonas con enfoque, la congelación o captación borrosa, el ruido... Todos estos recursos son útiles para que el fotógrafo comunique aquella imagen que busca. El afán por dominar la técnica y las herramientas fotográficas tiene como última intención mejorar nuestra capacidad comunicativa y creativa. A lo largo de este trabajo ilustraremos nuestros planteamientos con imágenes que surgen de esta vocación. En el capítulo primero se muestra la evolución de la práctica fotográfica a partir de la obra de algunos de los fotógrafos más notables. Reflexionamos sobre la evolución del concepto, de la fotografía como reproductora de la realidad, desde el nacimiento del medio hasta nuestros días. Además de incorporar reflexiones estéticas sobre el medio digital, nos detendremos en su origen tecnológico y en su desarrollo mercantil. El capítulo segundo introducimos los principios generales de la exposición, que son comunes a la fotografía analógica, y abordamos la especificidad de la exposición digital. Comenzamos a realizar pruebas y a extraer conclusiones para la maximización del control expositivo. En el capítulo tercero aportamos los fundamentos del color: la fidelidad del color, la amplitud de tonos y la resolución forman parte de este razonamiento. Estudiamos el rendimiento de los archivos digitales y la compresión. Se aportan soluciones prácticas encaminadas a la obtención de la mejor reproducción de la escena. La resolución de salida, impresión, pantalla y entrada es un apartado que aporta delimita el concepto de resolución abordando sus diferentes significados. En el capítulo cuarto abordamos las prácticas profesionales actuales, analizando la información extraída de las encuestas a los profesionales. Se trata un punto de partida para plantear nuestras primeras valoraciones, preguntas y suposiciones que tendrán respuesta y desarrollo en los siguientes capítulos. En el capítulo quinto experimentamos la influencia de la exposición en la captación de la información tonal y en la representación del color. Se analiza la exposición con archivos JPEG y se proponen soluciones para su maximización. La comparación entre el rendimiento del archivo RAW y el JPEG nos induce a propuestas diferentes para su tratamiento. Se explica el funcionamiento y los parámetros de ajuste básico en un archivo en bruto como antesala al análisis de la exposición con RAW. Proponemos dinámicas para el mejor ajuste de la exposición, y justificamos nuestras propuestas, profundizando en el análisis de las alteraciones cromáticas que se pueden producir según el ajuste de la exposición. En el capítulo sexto presentamos soluciones concretas para el tratamiento de la exposición en postproducción. Se analizan diferentes utilidades del programa Phostoshop y del conversor Camera RAW. Establecemos comparativas y proponemos qué herramientas ofrecen el mejor rendimiento. Se aportan soluciones originales para la conversión tonal a monocromo. Se aportan soluciones para la corrección del color minimizando la desviación de la exposición, y para la corrección de la exposición minimizando la desviación del color. La facilidad de la nueva tecnología digital para generar representaciones manipuladas con una total maleabilidad de la exposición, se ejemplifica con un fotomontaje. La tesis termina exponiendo las conclusiones que están relacionadas con el objetivo y planteamiento de la investigación.Our aim is to research the peculiarities of digital exposure, to observe the practice of professional digital photography and to put forward new techniques for controlling exposure. Chapter 1 shows how the practice of photography has evolved over the years, looking at the works of some of the major exponents of photography. We reflect upon how the concept has evolved - considering photography as a means of reproducing reality - from its dawning until the present day. In Chapter 2 we introduce the general principles of exposure and come to a range of conclusions on how to maximize exposure control. Chapter 3 addresses the fundamentals of colour and looks at the rendering of digital files. In Chapter 4 we look at current professional practice and analyse findings obtained with surveys among professional photographers. Chapter 5 deals with the influence of exposure in the capture of tonal information and in the representation of colour. We analyse exposure with JPEG/RAW files and propose a range of solutions for their maximization. Chapter 6 puts forward concrete solutions for treating exposure at the post-production stage. The main topics of our Conclusions are: the reproduction of colour in digital photography, the manipulation of digital files and adjustments at the post-production stage

Conservation of aging and cancer epigenetic signatures across human and mouse

Aging and cancer are two interrelated processes, with aging being a major risk factor for the development of cancer. Parallel epigenetic alterations have been described for both, although differences, especially within the DNA hypomethylation scenario, have also been recently reported. While many of these observations arise from the use of mouse models, there is a lack of systematic comparisons of human and mouse epigenetic patterns in the context of disease. However, such comparisons are significant as they allow to establish the extent to which some of the observed similarities or differences arise from pre-existing species-specific epigenetic traits. Here, we have used reduced representation bisulfite sequencing to profile the brain methylomes of young and old, tumoral and non-tumoral brain samples from human and mouse. We first characterized the baseline epigenomic patterns of the species and subsequently focused on the DNA methylation alterations associated with cancer and aging. Next, we described the functional genomic and epigenomic context associated with the alterations, and finally we integrated our data to study interspecies DNA methylation levels at orthologous CpG sites. Globally, we found considerable differences between the characteristics of DNA methylation alterations in cancer and aging in both species. Moreover, we describe robust evidence for the conservation of the specific cancer and aging epigenomic signatures in human and mouse. Our observations point towards the preservation of the functional consequences of these alterations at multiple levels of genomic regulation. Finally, our analyses reveal a role for the genomic context in explaining disease- and species-specific epigenetic traits.© The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution

Search for the decay D0→π+π−μ+μ−

A search for the D0→π+π−μ+μ− decay, where the muon pair does not originate from a resonance, is performed using proton–proton collision data corresponding to an integrated luminosity of 1.0 fb−1 recorded by the LHCb experiment at a centre-of-mass energy of 7 TeV. No signal is observed and an upper limit on the relative branching fraction with respect to the resonant decay mode D0→π+π− φ(→μ+μ− ), under the assumption of a phase-space model, is found to be B D0→π + π − μ + μ − /B D0→π + π − φ →μ + μ − < 0.96 at 90% confidence level. The upper limit on the absolute branching fraction is evaluated to be B(D0→π+π−μ+μ− ) < 5.5×10−7 at 90% confidence level. This is the most stringent to date.S

Evidence for the decay X(3872) →ψ(2S)γ

Evidence for the decay mode X(3872) →ψ(2S)γin B+→X(3872)K+decays is found with a sig-nificance of 4.4 standard deviations. The analysis is based on adata sample of proton–proton collisions, corresponding to an integrated luminosity of3fb−1, collected with the LHCb detector, at centre-of-mass energies of 7and8TeV. The ratio of the branching fraction of the X(3872) →ψ(2S)γdecay to that of the X(3872) →J/ψγdecay is measured to be B(X(3872)→ψ(2S)γ) B(X(3872)→J/ψγ) = 2.46± 0.64±0.29, where the first uncertainty is statistical and the second is systematic. The measured value does not support apureD¯ D∗molecular interpretation of the X(3872)state.S

Study of forward Z + jet production in pp collisions at √s = 7 TeV

A measurement of the Z(→ μ + μ −) + jet production cross-section in pp collisions at a centre-of-mass energy √s = 7 TeV is presented. The analysis is based on an integrated luminosity of 1.0 fb−1 recorded by the LHCb experiment. Results are shown with two jet transverse momentum thresholds, 10 and 20 GeV, for both the overall cross-section within the fiducial volume, and for six differential cross-section measurements. The fiducial volume requires that both the jet and the muons from the Z boson decay are produced in the forward direction (2.0 < η < 4.5). The results show good agreement with theoretical predictions at the second-order expansion in the coupling of the strong interaction.S

Study of J/ψ production and cold nuclear matter effects in pPb collisions at √sNN = 5 TeV

The production of J/ψ mesons with rapidity 1.5 < y < 4.0 or −5.0 < y < −2.5 and transverse momentum p T < 14 GeV/c is studied with the LHCb detector in proton-lead collisions at a nucleon-nucleon centre-of-mass energy √sNN = 5TeV. The J/ψ mesons are reconstructed using the dimuon decay mode. The analysis is based on a data sample corresponding to an integrated luminosity of about 1.6 nb−1. For the first time the nuclear modification factor and forward-backward production ratio are determined separately for prompt J/ψ mesons and J/ψ from b-hadron decays. Clear suppression of prompt J/ψ production with respect to proton-proton collisions at large rapidity is observed, while the production of J/ψ from b-hadron decays is less suppressed. These results show good agreement with available theoretical predictions. The measurement shows that cold nuclear matter effects are important for interpretations of the related quark-gluon plasma signatures in heavy-ion collisions.S

Measurement of the B+c meson lifetime using B+c→J/ψμ+νμX decays

The lifetime of the B+c meson is measured using semileptonic decays having a J/ψ meson and a muon in the final state. The data, corresponding to an integrated luminosity of 2 fb −1, are collected by the LHCb detector in pp collisions at a centre-of-mass energy of 8 TeV. The measured lifetime is τ=509±8±12 fs, where the first uncertainty is statistical and the second is systematic.S

Search for CP violation in the decay D+→π−π+π+

A search for CP violation in the phase space of the decay D+→π−π+π+ is reported using pp collision data, corresponding to an integrated luminosity of 1.0 fb−1, collected by the LHCb experiment at a centreof- mass energy of 7 TeV. The Dalitz plot distributions for 3.1×106 D+ and D− candidates are compared with binned and unbinned model-independent techniques. No evidence for CP violation is foundS

Measurement of the flavour-specific CP-violating asymmetry assl in B0s decays

The CP-violating asymmetry as sl is studied using semileptonic decays of B0s and B0s mesons produced in pp collisions at a centre-of-mass energy of 7 TeV at the LHC, exploiting a data sample corresponding to an integrated luminosity of 1.0 fb−1. The reconstructed final states are D± s μ∓, with the D± s particle decaying in the φπ± mode. The D± s μ∓ yields are summed over B0s and B0s initial states, and integrated with respect to decay time. Data-driven methods are used to measure efficiency ratios. We obtain as sl = (−0.06±0.50±0.36)%, where the first uncertainty is statistical and the second systematic.S

Observation of associated production of a Z boson with a D meson in the forward region

A search for associated production of a Z boson with an open charm meson is presented using a data sample, corresponding to an integrated luminosity of 1.0 fb−1 of proton-proton collisions at a centre-of-mass energy of 7TeV, collected by the LHCb experiment. Seven candidate events for associated production of a Z boson with a D0 meson and four candidate events for a Z boson with a D+ meson are observed with a combined significance of 5.1 standard deviations. The production cross-sections in the forward region are measured to be $σZ→μ+μ−,D0=2.50±1.12±0.22 pbσZ→μ+μ−,D+=0.44±0.23±0.03 pb,$ where the first uncertainty is statistical and the second systematic.S