HD 106906 is a young, binary stellar system, located at ~103.3 parsecs away in the Lower Centaurus Crux (LCC) group. This system is completely unique among known systems in that it contains an asymmetrical debris disk, as well as an 11 M(Jup) planet companion, at a separation of ~735 AU. Only 4 other systems are known to contain both a disk and detected planet, where HD 106906 is the only one in which the planet has apparently been ejected. Furthermore, the debris disk is nearly edge on, and extends roughly from 70 AU to >500 AU, where previous polarimetric studies with HST have shown the outer regions to have high asymmetry. The presence of a planet companion sparks questions about the origin of this asymmetry. To better understand the structure and composition of the disk, deeper data have been taken with the Gemini Planet Imager (GPI), which we have used to perform a deep polarimetric study of HD 106906’s asymmetrical debris disk. The data were taken in the H-band, and were supplemented with both J- and K1-band polarimetric data which have been obtained through one of GPI’s Large and Long Programs (LLP). Polarimetry is important in the study of debris disks in scattered light, as it helps us constrain their dust grain characteristics, as well as allowing us to obtain high-contrast images. Modelling the disk, along with an empirical analysis of our data, supports a disk that is asymmetrical in surface brightness and structure, as well as a disk that is highly eccentric. These results will be discussed in terms of possible sources of asymmetry, such as dynamical interaction with the planet companion HD 106906b. / Graduate / 2021-07-26

abstract: Part I – I analyze a database of Smoothed Particle Hydrodynamics (SPH) simulations of collisions between planetary bodies and use the data to define semi-empirical models that reproduce remant masses. These models may be leveraged when detailed, time-dependent aspects of the collision are not paramount, but analytical intuition or a rapid solution is required, e.g. in ‘N-body simulations’. I find that the stratification of the planet is a non-negligible control on accretion efficiency. I also show that the absolute scale (total mass) of the collision may affect the accretion efficiency, with larger bodies more efficiently disrupting, as a function of gravitational binding energy. This is potentially due to impact velocities above the sound speed. The interplay of these dependencies implies that planet formation, depending on the dynamical environment, may be separated into stages marked by differentiation and the growth of planets more massive than the Moon. Part II – I examine time-resolved neutron data from the Dynamic Albedo of Neutrons (DAN) instrument on the Mars Science Laboratory (MSL) Curiosity rover. I personally and independently developed a data analysis routine (described in the supplementary material in Chapter 2) that utilizes spectra from Monte Carlo N-Particle Transport models of the experiment and the Markov-chain Monte Carlo method to estimate bulk soil/rock properties. The method also identifies cross-correlation and degeneracies. I use data from two measurement campaigns that I targeted during remote operations at ASU. I find that alteration zones of a sandstone unit in Gale crater are markedly elevated in H content from the parent rock, consistent with the presence of amorphous silica. I posit that these deposits were formed by the most recent aqueous alteration events in the crater, since subsequent events would have produced matured forms of silica that were not observed. I also find that active dunes in Gale crater contain minimal water and I developed a Monte Carlo phase analysis routine to understand the amorphous materials in the dunes. / Dissertation/Thesis / Table 1: Giant impact SPH results for Chapter 1 / Table 2: Giant impact SPH results for Chapter 1 / Table 3: Giant impact SPH results for Chapter 1 / Doctoral Dissertation Geological Sciences 2019

The subsurface igneous biome contains a vast portion of Earth's total biomass, yet we still know so little about it. Igneous environments such as iron-rich ocean crust and lava tubes may also host analogs to chemolithotrophically-driven life on other planets, so studying life in this biome is essential to understanding how life may survive on other planets. In this study, three igneous surface and subsurface environments were investigated for microbial preference for olivine, microbial physiologies and phylotypes present on olivine, and microbial growth on olivine in the laboratory via iron oxidation. These environments include a subseafloor borehole drilled into the ocean crust basalt basement, a lava tube with perennial ice, and a trio of Columbia River basalt-hosted freshwater terrestrial habitats. The subseafloor borehole (IODP Hole 1301A) is situated on the eastern flank of Juan de Fuca Ridge (JFR) and was used in the first long-term deployment of microbial enrichment flow cells using osmotically-driven pumps. The flow cells contained igneous minerals and glasses, for which cell density and microbial abundances were evaluated. Total cell density and viable oligotrophs were highest for Fe(II)-rich olivines. Organotrophic bacterial isolates were capapble of iron oxidation and nitrate reduction, and grew on olivine in the laboratory. Putative neutrophilic iron oxidizers were also isolated from igneous riparian and cave environments in northwest and central Oregon. Isolated bacteria from all three environments were capable of chemolithotrophic growth with olivine and oxygen or nitrate in the laboratory. Bacteria isolated from river basalt were putatively capable of producing alteration textures on olivine surfaces in culture. Microbial life in the igneous subsurface preferentially attach to Fe²⁺-rich minerals, which suggests that life in the subsurface is heterogeneously distributed. The isolation of oligotrophic iron oxidizers that grow on olivine suggests that olivine supports a chemolithotrophic subsurface community based on primary productivity via iron oxidation. This generation of biomass on olivine surfaces creates organic carbon-rich coated mineral surfaces that may support a more complex community. The identification of Mars analogs living in Oregon lava tubes and the discovery that iron oxidizers may produce biosignatures on olivine surfaces are key findings that may provide the foundation for a new chapter in the search for life on Mars.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20182号 / 理博第4267号 / 新制||理||1613(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 嶺重 慎, 准教授 前田 啓一, 教授 長田 哲也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

A research report submitted In partial fulfilment for the degree Master of Science (Geographical Information Systems & Remote Sensing). to the School of Geography, Archaeology & Environmental Studies, University of the Witwatersrand, Johannesburg , July 2017 / The nature of urban development experienced by mining towns across the world has been a subject of concern among urban planners because of its transitory nature. Most times mining towns develop gloriously into booming urban centres that create employment, generate wealth and satisfaction. All these fades into oblivion as soon as the mines get depleted. Mining towns often go through a number of urban processes which have been considered an expression of ‘infrastructural violence’ especially in the earlier stage of urban growth, and continually persists throughout the town’s life span. This research sought to reconstruct the history of urban development in the mining town of Virginia, Free State, and to quantify the manifestations of infrastructural violence throughout its timeline using GIS and remote sensing. Hence, land use and land cover maps were produced from aerial photographs, topographical maps and Landsat images through manual on-screen digitizing and classification using supervised support vector machine algorithms. Land use change detection analysis was conducted on the produced images using the cross classification and tabulation tool of QGIS 2.18.4 and the post classification tool of ENVI 5.3. Landscape metrics were employed to calculate the dimensions of growth and change experienced by all the land use classes during the timeline under study. Results obtained from this study confirmed the thoughts and findings of several theories vis a vis the nature of mining towns. Results reveal a rapid growth in the urban formal land use class up until 1995 with urban expansion and sprawl happening in the years between 1986 and 1995 with metrics of CA, NP and ED multiplying to twice their initial values ten years earlier. The urban informal land use class also experienced its subtle growth throughout the timeline of the study with its own urban expansion also happening between 1986 and 1995 with double increase in CA, NP and ED metric values. However, unlike the formal class that experienced decline after this period of urban expansion, the informal class continued to experience growth up until the end of the study period. Infrastructural violence was measured using the fractal dimension index (AWMPFD) of the landscape metrics for the formal and informal LU class. The results reveal continuous fragmentation throughout the period of study but with higher values in the years in which urban development started. / LG2018

No description available.

Since the first warnings on the limits of planet Earth, 50 years ago, policies havenot been sufficient and fast enough to create a more sustainable world, which is todayillustrated by climate change, an increase in resource scarcity, and tremendousbiodiversity loss. Cities have been playing an important role in those environmentalconsequences, today accounting for 60% of greenhouse gases. However, citiesare designed by urban planners, who have a great influence on their projects inthe early planning phases. Thus, there is an urge to provide urban planners witheffective decision support tools that allow them to have in-depth knowledge of theenvironmental consequences of their choices.This is the goal of the ”Energy Carbon District”(ECD) methodology implementedin the Urban Print software, a project launched in 2017 by the FrenchAgency for Ecological Transition (ADEME). This tool sets out the first methodologicalchoices for carrying out life cycle analyses at the district level, right fromthe first stages of planning.The goal of this master thesis was to understand the strength and weaknessesof the ECD methodology and Urban Print software, and conduct a district LCAanalysis on a residential neighbourhood in order to get lessons on the most impactingdistricts’ elements, and on the best strategies to reduce those impacts.In this context, the study first provides an extensive literature review on the LCAmethodology, construction products LCA, buildings LCA, and districts LCA. Then,multiple district LCA are conducted on a generic new residential neighbourhoodlocated in Bayonne (France), using different parameters, and different weightingmethodologies.Our case study showed that energy, mobility, and construction products & equipmentare successively the three main contributors to districts’ impacts in a Businessas-usual scenario. ”Energy efficiency” and ”low impacting energy production” werethe two most effective leverages of urban planners to reduce environmental impacts,reducing the total weighed impacts by 21% to 34.6% compared to the Businessas-usual scenario. Once those leverages were activated, mobility and constructionproducts & equipment became the two first contributors, but very few leveragescould be used to reduce those impacts.In the end, the literature review and case study, allowed to highlight the strengthsand weaknesses of the ECD methodology, and the next challenges for district LCAstandardization. One challenge that stands out is the development of tools able toquantify mobility-related impacts based on more district parameters than just thelocation.

This dissertation investigates two stellar systems known to contain extrasolar planets. It is comprised of five chapters that are readily divided into three independent but related analyses. Chapter 1 reports on the analysis of low signal-to-noise secondary-eclipse observations of the Neptune-sized exoplanet GJ 436b using the Spitzer Space Telescope in multiple infrared channels. The measured wavelength-dependent eclipse depths provide constraints on the planet’s dayside atmospheric composition and thermal profile. The analysis indicates that GJ 436b’s atmosphere is abundant in carbon monoxide and deficient in methane relative to thermochemical equilibrium models for the predicted hydrogen-dominated atmosphere. Chapter 2 discusses the techniques used to analyze GJ 436b, introduces the Least Asymmetry centering method and compares its effectiveness to two existing techniques, and describes the functions used to model Spitzer’s position- and time-dependent systematics. Additionally, it includes best-fit parameters with uncertainties, histograms of the free parameters, and correlation plots between free parameters. Chapter 3 reports on the analysis of eleven HD 149026b secondary-eclipse observations at five Spitzer wavelengths plus three primary-transit observations at 8.0 µm. Chemical-equilibrium models find no indication of a temperature inversion in the dayside atmosphere of HD 149026b. The best-fit model favors large amounts of CO and CO2 , moderate heat redistribution (f = 0.5), and a strongly eniii hanced metallicity. These analyses use BiLinearly-Interpolated Subpixel Sensitivity (BLISS) mapping and parameter orthogonalization. The former is a new technique to model two position-dependent systematics, intrapixel variability and pixelation. The latter is a technique that accelerates the convergence of Markov chains that employ the Metropolis random walk sampler. Chapter 4 reports on the detection of GJ 436c, a 0.65 ± 0.04 R⊕ exoplanet transiting a nearby M-dwarf star with a period of 1.365862 ± 8×10−6 days. It also presents evidence for a similarly sized exoplanet candidate (currently labeled UCF-1.02) orbiting the same star with an undetermined period. Assuming an Earth-like density of 5.515 g/cm3 , GJ 436c has a predicted mass of 0.28 Earth-masses (M⊕, 2.6 Mars-masses) and a surface gravity of 0.65 g (where g is the gravity on Earth). Its weak gravitational field and close proximity to its host star imply that GJ 436c is unlikely to have retained its original atmosphere; however, a transient atmosphere is possible if recent impacts or tidal heating were to supply volatiles to the surface. Chapter 5 presents numerical simulations of the GJ 436 system using the Mercury N-body integrator and detailed calculations used to constrain the atmospheric composition of the sub-Earth-sized planet GJ 436c. The simulations find a ∼35-year periodic trend in the osculating elements wherein GJ 436c’s eccentricity varies between 0 and 0.21, its peak-to-trough inclination amplitude is 3.2◦ , and transit-timing variations range from ±200 to ±3 minutes.

This dissertation explored how humanitarian organisations have supported Georgia to achieve the UN 2030 Sustainable Development Goals (SDG) of 2015, in particular the Planet Goals. It has proven difficult for Member States to turn the SDGs into national policy. Middle-income countries face challenges to focus on all goals simultaneously, while balancing economic development needs and environmental protection ambitions. Humanitarian organisations play a prominent role supporting the implementation of the SDGs. Therefore, this dissertation aims to answer the research question: How has humanitarian organisations been effective in supporting the implementation of the SDGs, particularly the Planet Goals, in Georgia?The theoretical backing to the research is based Arhin (2016), who studied humanitarian organisations and SDGs in Ghana. Arhin outlined three main roles of organisations in SDG work namely, implementation, advocacy, and facilitation. In addition, theories concerning the operational space of organisations as well as the SDGs as a system was used. A conceptual framework was created to guide the data collection and the analysis.The research was conducted as a qualitative case study, through interviews and documents. Nine interviews were conducted, along with a review of external aid reports, Voluntary National Reviews for 2016 and 2020 and the European Union-Georgia Association Agreement. The material was analysed using critical discourse theory, using a programme called ATLAS.ti.The results found that Georgia’s development agenda has an explicit focus on economic growth rather than environmental sustainability. There is a large disparity in society with substantial urban-rural divides. A part of the population needs basic necessities, typically in rural areas, whereas cities are more developed. The European Union-Georgia Association Agreement has had a large influence on the development focus and agenda in Georgia, and the Government prioritises policies to meet the requirements under this agreement to advance its European Union aspirations. The research concluded that there is no organised work towards implementing the SDGs in Georgia. Organisations designing and implementing projects align with the obligations under the European Union Association Agreement, and subsequently align project objectives and impact with the SDGs, as long as there is a natural fit between the set project objectives and the SDGs. Thus, SDGs do not guide the objective setting for projects. There is barely any advocacy of the 2030 Agenda in Georgia. In terms of facilitation, the SDGs are addressed at institutional level, which is somewhat politicised. The adoption of the SDGs can be considered a political manoeuvre to confirm Georgia’s commitment as a member of the global order, whereas the true focus of Georgia’s development agenda focuses on economic growth under the European Union-Georgia Association Agreement.

<p dir="ltr">We present a model describing an impact jetting origin for the formation of chondrules, the mm– scale, igneous components of chondritic meteorites which originated during the first few million years of solar system history. The ubiquity of chondrules in both non-carbonaceous and carbonaceous chondrites suggests their formation persisted throughout the protoplanetary disk, but their formation mechanism is debated and largely unexplored in the outer disk.<b> </b>Using the iSALE2D shock physics code, we generate models of the process of impact jetting during mixed material (dunite and water ice) impacts that mimic accretionary impacts that form giant planet cores. We show that the process of impact jetting provides the conditions necessary to satisfy critical first-order constraints on chondrule characteristics (size, shape, thermal history). We then explore the implications of chondrule formation by impact jetting during the formation of giant planet cores by combining the original results with simulations of giant planet core accretion generated using a Lagrangian Integrator for Planetary Accretion and Dynamics (LIPAD) code.</p><p dir="ltr">The second closest Galilean satellite to Jupiter is Europa, an ocean world with an outer ice shell and subsurface water ocean encapsulating its rocky core. The surface of Europa is covered in double ridges. These features are defined by two topographic highs about 100 meters tall, with a central trough between them, which extend for hundreds of kilometers over the surface of the moon. Accurate models for the formation of features as prominent as double ridges will help to further constrain the interior structure and dynamics of the interior of the body. We use analytical and numerical finite element models to show that the incremental growth of an ice wedge within the ice shell can cause deformation matching the observed size and shape of observed double ridges on Europa. These models indicate that the total height and width of the ridges correspond to the depth of the wedge, so that deeper wedges create shorter and broader ridges. We consider different sources for the wedge material and ultimately argue in favor of local sources of liquid water within the ice shell.</p>