Values of H_0 from Models of the Gravitational Lens 0957+561

The lensed double QSO 0957+561 has a well-measured time delay and hence is useful for a global determination of H0. Uncertainty in the mass distribution of the lens is the largest source of uncertainty in the derived H0. We investigate the range of \hn produced by a set of lens models intended to mimic the full range of astrophysically plausible mass distributions, using as constraints the numerous multiply-imaged sources which have been detected. We obtain the first adequate fit to all the observations, but only if we include effects from the galaxy cluster beyond a constant local magnification and shear. Both the lens galaxy and the surrounding cluster must depart from circular symmetry as well. Lens models which are consistent with observations to 95% CL indicate H0=104^{+31}_{-23}(1-\kthirty) km/s/Mpc. Previous weak lensing measurements constrain the mean mass density within 30" of G1 to be kthirty=0.26+/-0.16 (95% CL), implying H0=77^{+29}_{-24}km/s/Mpc (95% CL). The best-fitting models span the range 65--80 km/s/Mpc. Further observations will shrink the confidence interval for both the mass model and \kthirty. The range of H0 allowed by the full gamut of our lens models is substantially larger than that implied by limiting consideration to simple power law density profiles. We therefore caution against use of simple isothermal or power-law mass models in the derivation of H0 from other time-delay systems. High-S/N imaging of multiple or extended lensed features will greatly reduce the H0 uncertainties when fitting complex models to time-delay lenses.Comment: AASTEX, 48 pages 4 figures, 2 tables. Also available at: http://www.astro.lsa.umich.edu:80/users/philf/www/papers/list.htm

A Library for Declarative Resolution-Independent 2D Graphics

The design of most 2D graphics frameworks has been guided by what the computer can draw efficiently, instead of by how graphics can best be expressed and composed. As a result, such frameworks restrict expressivity by providing a limited set of shape primitives, a limited set of textures and only affine transformations. For example, non-affine transformations can only be added by invasive modification or complex tricks rather than by simple composition. More general frameworks exist, but they make it harder to describe and analyze shapes. We present a new declarative approach to resolution-independent 2D graphics that generalizes and simplifies the functionality of traditional frameworks, while preserving their efficiency. As a real-world example, we show the implementation of a form of focus+context lenses that gives better image quality and better performance than the state-of-the-art solution at a fraction of the code. Our approach can serve as a versatile foundation for the creation of advanced graphics and higher level frameworks

A spectroscopically confirmed z=1.327 galaxy-scale deflector magnifying a z~8 Lyman-Break galaxy in the Brightest of Reionizing Galaxies survey

We present a detailed analysis of an individual case of gravitational lensing of a $z\sim8$ Lyman-Break galaxy (LBG) in a blank field, identified in Hubble Space Telescope imaging obtained as part of the Brightest of Reionizing Galaxies survey. To investigate the close proximity of the bright ($m_{AB}=25.8$) $Y_{098}$-dropout to a small group of foreground galaxies, we obtained deep spectroscopy of the dropout and two foreground galaxies using VLT/X-Shooter. We detect H-$\alpha$, H-$\beta$, [OIII] and [OII] emission in the brightest two foreground galaxies (unresolved at the natural seeing of $0.8$ arcsec), placing the pair at $z=1.327$. We can rule out emission lines contributing all of the observed broadband flux in $H_{160}$ band at $70\sigma$, allowing us to exclude the $z\sim8$ candidate as a low redshift interloper with broadband photometry dominated by strong emission lines. The foreground galaxy pair lies at the peak of the luminosity, redshift and separation distributions for deflectors of strongly lensed $z\sim8$ objects, and we make a marginal detection of a demagnified secondary image in the deepest ($J_{125}$) filter. We show that the configuration can be accurately modelled by a singular isothermal ellipsoidal deflector and a S\'{e}rsic source magnified by a factor of $\mu=4.3\pm0.2$. The reconstructed source in the best-fitting model is consistent with luminosities and morphologies of $z\sim8$ LBGs in the literature. The lens model yields a group mass of $9.62\pm0.31\times10^{11} M_{\odot}$ and a stellar mass-to-light ratio for the brightest deflector galaxy of $M_{\star}/L_{B}=2.3^{+0.8}_{-0.6} M_{\odot}/L_{\odot}$ within its effective radius. The foreground galaxies' redshifts would make this one of the few strong lensing deflectors discovered at $z>1$.Comment: Accepted for publication in MNRAS. 16 pages, 11 figures, 3 table

Design and Development of Advanced Adaptive Polymer Lenses

The dissertation presented here describes advancements made in adaptive polymer lens design and implementation. Singlets and doublets lenses were constructed for visible, short- wavelength infrared (SWIR), and middle-wavelength infrared (MWIR)applications. The lenses are implemented in a variety of tactical imaging systems to demonstrate their performance. A process was developed that defines the allowable fabrication variables, first for APL singlets and then for APL doublets. A first-order finite element model is described that enables going from an optical design to APL fabrication. This model was then extended to the design of fluidic doublets, which are equivalent to their two-element glass counter-parts. Two constant volume fluidic chambers were enclosed by three flexible membranes resulting in a variable focal length doublet. Chromatic focal shift was then used to compare numerical modeling to experimentally measured results. These same tools, methodology, and process were lastly used in the definition and fabrication of the SWIR and MWIR adaptive polymer lens for tactical systems. vi Imaging and illumination systems are presented, based on these lensesnotably an adaptive zoom imaging system, in the MWIR. This is the first known instance of such a system in this band

Strong Gravitational Lens Modelling

The objective of this project is to examine the extent to which strong gravitational lensing can constrain cosmological parameters. I present the results of applying a modified version of an existing model of strong gravitational lensing to forthcoming surveys by Euclid, currently scheduled to launch in 2021, and investigate also how the model may be adapted further to accommodate background galaxy sources that have not previously been included. The initial model, on which the modifications are based, was first constructed by Dr Tom Collett (Collett 2015) with the source code, at the time of writing, freely available on https://github.com/tcollett/LensPop. The study commences with a review of the existing model's code, which includes a mapping of the key dependencies. As a natural consequence of this, discrepancies that I have identified within the code are detailed, as are inconsistencies with the supporting article by Collett (2015) in which the principal features of his model are described. Once the discrepancies are corrected, or otherwise resolved, the modified model is run and the implications of these assessed: most are found to be minor, although more significant issues arise when the model is tested under non-standard cosmologies. An analysis of the results for both Euclid's Wide Field and Deep Field surveys is presented using the modified model, as are predictions by the model for the forthcoming Cosmic Evolution Survey (COSMOS) and the Wide Field InfraRed Survey Telescope (WFIRST). In comparison to the Wide Field survey, the model's prediction of a 7-fold increase in the sky density of detectable lenses for the Euclid Deep Field survey is found to be mainly due to an increased sensitivity of 2 magnitudes in the latter. For the COSMOS survey, a prediction of some 120 lenses suggests that further lensing systems have yet to be confirmed in the survey field whereas, in the case of WFIRST, a prediction of just under 100,000 lenses means its increased depth almost compensates for the smaller area, when compared to the Euclid Wide Field survey; compared to the Euclid Deep Field survey, on the other hand, WFIRST is both wider and deeper, with this prediction representing a 25-fold increase in the number of discoverable lenses. The extent to which the model can constrain cosmological parameters is then considered. This requires an investigation not only of the model's direct sensitivity to a cosmology by virtue of the lensing equations, but also of the model's sensitivity to any astrophysical assumptions, such as those governing density or luminosity functions, that are intrinsic to the code. I find there is prima facie evidence that the model does constrain the cosmologies tested, and conclude also that it is not particularly sensitive to those astrophysical assumptions. Finally, by replacing the simulated source data described in Collett (2015) with a more appropriate mock catalogue, I examine the predictions of the model when submillimetre galaxies are considered. In this respect, a source population comprising solely submillimetre galaxies gives rise to an under-prediction by the model of the number of lenses, when compared to other studies; furthermore, once adapted in this fashion, the model does not impose any significant constraints on the cosmologies tested

Set up of a light sheet fluorescence microscope for cellular studies

Light-sheet fluorescence microscopy (LSFM) has been present in cell biology laboratories for quite some time, mainly as custom-made systems, with imaging applications ranging from single cells (in the μm scale) to small organisms (mm). Such microscopes distinguish themselves for having very low phototoxicity levels and high spatial and temporal resolution, properties that render it ideal for 3D characterization of cell motility in migration and traction force studies. Cellular motion has proven to be essential in biological processes such as tumor metastasis and tissue development. Experimental setups make extensive use of microdevices (bioMEMS) that are providing higher degrees of empirical complexity. The following report details the process of setting-up a functional LSFM device for imaging cell motion in microfluidic devices. It begins with a brief summary of fluorescence imaging and current techniques, important to understand why single-plane illumination microscopy (SPIM) was chosen among other light-sheet methods. Then, the whole SPIM set-up process is described, containing explanations about the physical and material properties of the hardware used, the intricacies of the control system, and important procedures. These procedures include: calibration of the microscope, sample preparation in microdevices, and image acquisition from the software provided. Real fluorescence images acquired serve as evidence of the functionality of the instrument. The current limitations are highlighted, and pointers on how to improve or enhance the device are given. The report contains many diagrams, tables and pictures to aid in the understanding of important concepts. In the Annex, a comprehensive table listing the project costs by category is attached. This table includes links to the manufacturers and providers. The aim of this writing is to serve as an exhaustive guideline and be of reproducible use for researchers aiming to build SPIM systems for similar applications.Ingeniería Biomédic

Interactive Visualization Lenses:: Natural Magic Lens Interaction for Graph Visualization

Information visualization is an important research field concerned with making sense and inferring knowledge from data collections. Graph visualizations are specific techniques for data representation relevant in diverse application domains among them biology, software-engineering, and business finance. These data visualizations benefit from the display space provided by novel interactive large display environments. However, these environments also cause new challenges and result in new requirements regarding the need for interaction beyond the desktop and according redesign of analysis tools. This thesis focuses on interactive magic lenses, specialized locally applied tools that temporarily manipulate the visualization. These may include magnification of focus regions but also more graph-specific functions such as pulling in neighboring nodes or locally reducing edge clutter. Up to now, these lenses have mostly been used as single-user, single-purpose tools operated by mouse and keyboard. This dissertation presents the extension of magic lenses both in terms of function as well as interaction for large vertical displays. In particular, this thesis contributes several natural interaction designs with magic lenses for the exploration of graph data in node-link visualizations using diverse interaction modalities. This development incorporates flexible switches between lens functions, adjustment of individual lens properties and function parameters, as well as the combination of lenses. It proposes interaction techniques for fluent multi-touch manipulation of lenses, controlling lenses using mobile devices in front of large displays, and a novel concept of body-controlled magic lenses. Functional extensions in addition to these interaction techniques convert the lenses to user-configurable, personal territories with use of alternative interaction styles. To create the foundation for this extension, the dissertation incorporates a comprehensive design space of magic lenses, their function, parameters, and interactions. Additionally, it provides a discussion on increased embodiment in tool and controller design, contributing insights into user position and movement in front of large vertical displays as a result of empirical investigations and evaluations.Informationsvisualisierung ist ein wichtiges Forschungsfeld, das das Analysieren von Daten unterstützt. Graph-Visualisierungen sind dabei eine spezielle Variante der Datenrepräsentation, deren Nutzen in vielerlei Anwendungsfällen zum Einsatz kommt, u.a. in der Biologie, Softwareentwicklung und Finanzwirtschaft. Diese Datendarstellungen profitieren besonders von großen Displays in neuen Displayumgebungen. Jedoch bringen diese Umgebungen auch neue Herausforderungen mit sich und stellen Anforderungen an Nutzerschnittstellen jenseits der traditionellen Ansätze, die dadurch auch Anpassungen von Analysewerkzeugen erfordern. Diese Dissertation befasst sich mit interaktiven „Magischen Linsen“, spezielle lokal-angewandte Werkzeuge, die temporär die Visualisierung zur Analyse manipulieren. Dabei existieren zum Beispiel Vergrößerungslinsen, aber auch Graph-spezifische Manipulationen, wie das Anziehen von Nachbarknoten oder das Reduzieren von Kantenüberlappungen im lokalen Bereich. Bisher wurden diese Linsen vor allem als Werkzeug für einzelne Nutzer mit sehr spezialisiertem Effekt eingesetzt und per Maus und Tastatur bedient. Die vorliegende Doktorarbeit präsentiert die Erweiterung dieser magischen Linsen, sowohl in Bezug auf die Funktionalität als auch für die Interaktion an großen, vertikalen Displays. Insbesondere trägt diese Dissertation dazu bei, die Exploration von Graphen mit magischen Linsen durch natürliche Interaktion mit unterschiedlichen Modalitäten zu unterstützen. Dabei werden flexible Änderungen der Linsenfunktion, Anpassungen von individuellen Linseneigenschaften und Funktionsparametern, sowie die Kombination unterschiedlicher Linsen ermöglicht. Es werden Interaktionstechniken für die natürliche Manipulation der Linsen durch Multitouch-Interaktion, sowie das Kontrollieren von Linsen durch Mobilgeräte vor einer Displaywand vorgestellt. Außerdem wurde ein neuartiges Konzept körpergesteuerter magischer Linsen entwickelt. Funktionale Erweiterungen in Kombination mit diesen Interaktionskonzepten machen die Linse zu einem vom Nutzer einstellbaren, persönlichen Arbeitsbereich, der zudem alternative Interaktionsstile erlaubt. Als Grundlage für diese Erweiterungen stellt die Dissertation eine umfangreiche analytische Kategorisierung bisheriger Forschungsarbeiten zu magischen Linsen vor, in der Funktionen, Parameter und Interaktion mit Linsen eingeordnet werden. Zusätzlich macht die Arbeit Vor- und Nachteile körpernaher Interaktion für Werkzeuge bzw. ihre Steuerung zum Thema und diskutiert dabei Nutzerposition und -bewegung an großen Displaywänden belegt durch empirische Nutzerstudien