A Free-Form Lensing Grid Solution for A1689 with New Mutiple Images

Hubble Space Telescope imaging of the galaxy cluster Abell 1689 has revealed an exceptional number of strongly lensed multiply-imaged galaxies, including high-redshift candidates. Previous studies have used this data to obtain the most detailed dark matter reconstructions of any galaxy cluster to date, resolving substructures ~25 kpc across. We examine Abell 1689 (hereafter, A1689) non-parametrically, combining strongly lensed images and weak distortions from wider field Subaru imaging, and we incorporate member galaxies to improve the lens solution. Strongly lensed galaxies are often locally affected by member galaxies, however, these perturbations cannot be recovered in grid based reconstructions because the lensing information is too sparse to resolve member galaxies. By adding luminosity-scaled member galaxy deflections to our smooth grid we can derive meaningful solutions with sufficient accuracy to permit the identification of our own strongly lensed images, so our model becomes self consistent. We identify 11 new multiply lensed system candidates and clarify previously ambiguous cases, in the deepest optical and NIR data to date from Hubble and Subaru. Our improved spatial resolution brings up new features not seen when the weak and strong lensing effects are used separately, including clumps and filamentary dark matter around the main halo. Our treatment means we can obtain an objective mass ratio between the cluster and galaxy components, for examining the extent of tidal stripping of the luminous member galaxies. We find a typical mass-to-light ratios of M/L_B = 21 inside the r<1 arcminute region that drops to M/L_B = 17 inside the r<40 arcsecond region. Our model independence means we can objectively evaluate the competitiveness of stacking cluster lenses for defining the geometric lensing-distance-redshift relation in a model independent way.Comment: 23 pages with 25 figures Replced with MNRAS submitted version. Some figures have been corrected and minor text edit

The codification of local knowledges through digital cartographic artefacts: A Case study of the Humanitarian OpenStreetMap Team in Dar es Salaam, Tanzania.

The Humanitarian OpenStreetMap Team, affectionately known as HOT, worked on mapping the city of Dar es Salaam between 2014 and 2020. The efforts of HOT were designed to not only build a map of the city that would ‘put people on the map’, but to also use these maps to aid in development and humanitarian interventions through one of Africa’s fastest growing cities, all while using participatory mapping practices. This thesis examines the extent to which HOT has been able to achieve the creation of a new map of Dar es Salaam, the influence this map had on development projects, and the degree to which the map was built using participatory methods. The research undertook a deep analysis of map completion and accuracy and used interviews to explore the interplay between technology and micro/macro politics around the mapping of Dar es Salaam. Findings suggest that HOT is still underdeveloped as an organization and lacks the maturity to create true participatory models of working. That many of their practices were exclusionary to the local population and that weak management structures and procedures allowed colonial and ‘outsider’ saviour complexes to grow within the organisation. The work concludes by noting that HOT has begun to change many of its practices since 2020 where this research ends

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Department of Urban and Environmental Engineering (Environmental Science and Engineering )This thesis proposes a comprehensive view of teleconnection between the El Ni??o and Southern Oscillation (ENSO) and the Indian Ocean (IO). This study aims to 1) better understanding of dynamics underlying ENSO-IO teleconnection, 2) investigation of possible strengthening mechanisms of ENSO-IO teleconnection with multi-decadal climate change, 3) identification of ENSO-related predictability sources in dynamical seasonal prediction and future prospection. From these perspectives, this dissertation consists of following chapters. Chapter 1 summarizes current issues respect to ENSO teleconnection and research objectives. Chapter 2 investigates dynamics underlying ENSO teleconnection to regional precipitation around the IO. There are clear evidences in strengthening relationship of the ENSO-IO teleconnection since 1990s. Hence dynamics of strengthening ENSO-IO teleconnections are assessed with respect to decadal change of zonal sea surface temperature (SST) gradient in the equatorial Pacific Ocean. Chapter 3 assessed prediction skill and predictability sources of rainfall around the IO using state-of-the-art seasonal prediction system. The ENSO-IO teleconnection in the coupled models and their prospects with future scenarios are also investigated from the fifth phase of the Coupled Model Intercomparison Project (CMIP5). From these synthetic examinations for the ENSO-IO teleconnection, this thesis suggests that a better understanding of regional climate around the IO responses to ENSO with a seasonal evolution mechanism, which are intensified dynamical connection since the 1990s. By unveiling the dynamical mechanism underlying their decadal change, better seasonal prediction skills are expected with the ENSO-related precursors. Dynamical ensemble predictions from the North American Multi-model Ensemble show better prediction skills due to the decadal change of the ENSO-IO teleconnection. This study could contribute to better mitigations and adaptations of extreme climate variability such as drought and flood.clos

The architecture and acuity of critical systems thinking

This thesis looks at two critical urges in Critical Systems Thinking that both complement and critique each other. Firstly, there is an urge to construct in a critical manner. Secondly, there is an urge to be critical about such constructions. They complement and critique each other in the manner in which the second urge requires the first urge in order to understand what it means when one begins to create by construction, and also in which the first urge requires the second in order to understand the privileged position that construction is given in epistemology. These two urges give two stages.Construction relates to four clear conditions that develop from an Architectural study. This study offers two definitions of Architecture : structural longevity and relational modification. Consequently, a Structure and Process are established (first two stages) which together content an Architecture of Critical Systems Thinking (third stage). This Architecture is then applied to Systems Thinking through a study of five Systems Thinkers, this application offers an Architecture as commensurability (fourth stage). The Architecture is thereby offered as author.De-construction relates to four clear conditions that develop from the Architecture of Critical Systems Thinking. Each condition questions the Architectural authority to construct. The Process (reversed to complement and critique) questions the Structural consistency of the Architecture (first). A Structure of Acuity develops that maintains meaning where the Architecture neutralised meaning (second). A Contentless Acuity follows (third), thereby allowing the contentlessness of paradigm (in)commensurability to be discussed as an application of the Acuity of Critical Systems Thinking. The Acuity is thereby offered as reader.To balance these two urges is to read with authority

Payload training methodology study

The results of the Payload Training Methodology Study (PTMS) are documented. Methods and procedures are defined for the development of payload training programs to be conducted at the Marshall Space Flight Center Payload Training Complex (PCT) for the Space Station Freedom program. The study outlines the overall training program concept as well as the six methodologies associated with the program implementation. The program concept outlines the entire payload training program from initial identification of training requirements to the development of detailed design specifications for simulators and instructional material. The following six methodologies are defined: (1) The Training and Simulation Needs Assessment Methodology; (2) The Simulation Approach Methodology; (3) The Simulation Definition Analysis Methodology; (4) The Simulator Requirements Standardization Methodology; (5) The Simulator Development Verification Methodology; and (6) The Simulator Validation Methodology