How fast do Jupiters grow? Signatures of the snowline and growth rate in the distribution of gas giant planets

We present here observational evidence that the snowline plays a significant role in the formation and evolution of gas giant planets. When considering the population of observed exoplanets, we find a boundary in mass-semimajor axis space that suggests planets are preferentially found beyond the snowline prior to undergoing gap-opening inward migration and associated gas accretion. This is consistent with theoretical models suggesting that sudden changes in opacity -- as would occur at the snowline -- can influence core migration. Furthermore, population synthesis modelling suggests that this boundary implies that gas giant planets accrete ~ 70 % of the inward flowing gas, allowing ~ 30$ % through to the inner disc. This is qualitatively consistent with observations of transition discs suggesting the presence of inner holes, despite there being ongoing gas accretion.Comment: 7 pages, 6 figures, accepted for publication in Monthly Notices of the Royal Astronomical Societ

Emotional Intelligence and Organizational Context in Educational Leadership

This qualitative, multiple case study investigated how educational leaders used and manifested Emotional Intelligence (EI) skills and abilities in unique organizational contexts. The study was conducted with five principals in a large, urban school district. The principals were selected to participate based on the organizational context of their schools. Each site was profiled and subsequently categorized based on the unique dynamics of the school including, but not limited to cultural, social, political, environmental, economic, and temporal factors. The principals were interviewed using a common, open-ended interview protocol. The interviews contained questions about the school’s organizational context, the principal’s relationships with stakeholders, and the principal’s use of Emotional Intelligence (EI) skills and abilities in their role as the leader of the school. The interview transcripts were coded, analyzed, and compared with publicly available information about each school site to draw themes and conclusions to answer the research question: How do educational leaders exhibit and utilize EI within distinct organizational contexts? All five principals demonstrated evidence supporting the importance of EI skills and abilities in their role as principal and all five believed they could grow and develop their EI. The findings indicated differences in the use and manifestation of specific EI skills and abilities, from basic skills to advanced skills, across the different school contexts. This study was unique because it combined two, previously independent fields of study in the area of leadership: EI and organizational context

Examining the Production of Co-active Channels on YouTube and BitChute

A concern among content moderation researchers is that hard moderation measures, such as banning content producers, will push users to more extreme information environments. Research in this area is still new, but predominately focuses on one-way migration (from mainstream to alt-tech) due to this concern. However, content producers on alt-tech social media platforms are not always banned users from mainstream platforms, instead they may be co-active across platforms. We explore co-activity on two such platforms: YouTube and BitChute. Specifically, we describe differences in video production across 27 co-active channels. We find that the majority of channels use significantly more moral and political words in their video titles on BitChute than in their video titles on YouTube. However, the reasoning for this shift seems to be different across channels. In some cases, we find that channels produce videos on different sets of topics across the platforms, often producing content on BitChute that would likely be moderated on YouTube. In rare cases, we find video titles of the same video change across the platforms. Overall, there is not a consistent trend across co-active channels in our sample, suggesting that the production on alt-tech social media platforms does not fit a single narrative.Comment: This is a MeLa Lab Technical Repor

Powered Wheelchair Platform for Assistive Technology Development

Literature shows that numerous wheelchair platforms, of various complexities, have been developed and evaluated for Assistive Technology purposes. However there has been little consideration to providing researchers with an embedded system which is fully compatible, and communicates seamlessly with current manufacturer's wheelchair systems. We present our powered wheelchair platform which allows researchers to mount various inertial and environment sensors, and run guidance and navigation algorithms which can modify the human desired joystick trajectory, so as to assist users with negotiating obstacles, and moving from room to room. We are also able to directly access other currently manufactured human input devices and integrate new and novel input devices into the powered wheelchair platform for clinical and research assessment

Essays on Dynamic Contract Theory

This dissertation studies the role of asymmetric information in dynamic contracts. Through two chapters, I examine the relationship between constraints on liquidity and the dynamics of adverse selection. In general, these two features combine to generate inefficiency in the optimal contract, and each chapter explores the magnitude of this inefficiency in different dynamic settings. In the first chapter, I characterize the relationship between persistence in private information and liquidity. By contrast, in the second chapter, I highlight the impact of liquidity on dynamic network effects. More specifically, in my first chapter I study a dynamic adverse selection model where a long- lived agent contracts with a long-lived principal for the provision of a good in each period. The agent is liquidity constrained and possesses private information about her preferences for the principal’s good that evolve over time and are autocorrelated. Employing techniques from Fernandes and Phelan (2000), I characterize the optimal contract as the solution to a concave dynamic programming problem, where the state variables are the previous period’s reported type as well as on and off path promised expected lifetime utilities. Through analytical results and simulations, I find that the optimal contract backloads rents and that there exists a threshold state after which the contract calls for the efficient provision of the good. Moreover, the optimal contract exhibits short-run distortions in the provision of the good when the state is below the threshold. Notably, I find that the liquidity constraint causes inefficiency that lingers long after it would have been resolved if there were no constraints on the agent’s liquidity. On the other hand, in the second chapter I study a dynamic-adverse selection setting where a long- lived principal contracts with overlapping generations of agents for the provision of a service in each period. Throughout the duration of the contract, each agent’s preferences for the service are affected by both their privately observed, i.i.d. characteristic and the characteristic of any other agent contracting with the principal. I adopt the techniques of Krishna, Lopomo, and Taylor (2013) and characterize the optimal contract as the solution to a dynamic programming problem, where the state is promised lifetime utility. I find that the optimal contract is monotone in state, backloaded, and exhibits the no distortion at the top property. Moreover, the optimal contract is biased in favor of older agents.Doctor of Philosoph

Exploring the epistemic politics of urban niche experiments

Urban experiments have been initiated in several locations to purposively initiate and shape transitions to more sustainable urban socio-technical systems, e.g. for energy, water, mobility. Although knowledges produced within such learning spaces are often presented as logical, technical and rational (Vanolo, 2013 ; Kitchin, 2014), the actors and mechanisms which shape decisions are far from obvious, involving cultures, power relations and multiple logics that are profoundly political (Machin, 2013). This research presents a case study founded in a phronetic perspective (Flyvbjerg, 2001; Avelino and Grin, 2017), unpacking the epistemological politics of an urban experiment taking place within a ‘smart city’ programme. A ‘smart transport’ application for mobile phones, ‘MotionMap’ was developed to transform the mobility system of Milton Keynes, an expanding city located 80 km to the north of London, UK. The case study recognises power relations and reveals how various actors engaged in the development of this application have further rendered the MK mobility socio-technical system an object of urban governance

Global Navigation Satellite Systems disciplined oscillator synchronisation of multistatic radar

A fundamental challenge in the practical implementation of multistatic radar systems (MSRS) is the requirement for precise time and frequency synchronisation between the spatially separated radar nodes. The authors evaluate the performance of different classes of commercially available Global Navigation Satellite Systems (GNSS) timing receivers, Local Oscillators (LO) and GNSS Disciplined Oscillators (GNSSDOs) to determine the limitations of using one‐way GNSS Time and Frequency Transfer (TFT) in this application. From evaluating the performance of three pairs of GNSSDOs, it is concluded that one‐way GNSS TFT will likely be suitable only for the synchronisation of fully spatially coherent MSRS with carrier frequencies up to 100 MHz and waveform bandwidths up to 20 MHz. Whereas, in the case of short‐term spatially coherent MSRS, synchronisation of systems with carrier frequencies up to a few GHz and waveform bandwidths of over 100 MHz will likely be possible. The performance of the different classes of GNSSDOs during GNSS denial (holdover) are evaluated, where it is concluded that frequency offsets between LOs at the point of GNSS denial will often significantly contribute, or even dominate, the holdover performance. Analysis of two practical multistatic radar measurements verifies the function of using the GNSSDOs for wireless synchronisation of the ARESTOR MSRS