Exploring Structural and Electronic Properties of Triangular Adatom Layers on the Silicon Surface Through Adsorbate Doping

The analysis of the electronic structure and morphology of 1/3 monolayers (ML) of Sn or Pb on Si(111) and Ge(111) has played an important role in understanding the role of electronic correlations in two dimensions. Specifically, the two-dimensional lattice of partially filled dangling bonds of these so-called α-phases has been an important testbed for studying structural phase transitions and correlated electronic phenomena ever since the discovery of a surface charge density wave in the Pb/Ge(111) system more than two decades ago. With the exception of the novel Sn/Si(111) system, all $\alpha$-phases undergo a charge ordering transition at low temperature. The uniqueness of this surface has further been observed in modulation hole doping experiments, where we have shown that the Sn/Si(111) system shows clear signs of doped Mott physics. This provides a rare insight into cuprate-like physics in a sp3 bonded non-oxide system and suggests the possibility of realizing unconventional superconductivity on a conventional semiconductor platform. Indeed, recent measurements on this system reveals that the hole-doped Sn layers on a degenerately doped p-type Si(111) wafer are superconducting with a critical temperature of 4.7 ± 0.3 K. The triangular lattice symmetry and strong Mott correlations of the Sn-derived dangling bond surface state strongly suggest that the superconductivity may be unconventional and topologically non-trivial. This fascinating result motivates attempts to electron-dope this system using low-dose potassium deposition. Here, we find that potassium induces a charge ordering transition in the Sn sublattice. Temperature dependent studies on this surface reveal the complex interplay between the site location and diffusion of the K adatoms, and the charge ordering transition in the Sn sublattice. As the temperature increases from absolute zero, the K atoms start fluctuating about their equilibrium positions and eventually hop back and forth between neighboring lattice sites. During this process, long-range order is maintained. At higher temperature the K adatoms begin to diffuse over much longer distance, ultimately leading to a complete melting of the K sublattice. K diffusion induces charge fluctuations between the dangling bonds of the Sn sublattice, and ultimately leads to melting of the charge order of the Sn lattice through a displacive and subsequently an order-disorder transition. In combination with theoretical work, this provides a rare atomically resolved insight into a multistep 2D melting transition. Further studies are performed on the Pb/Si(111) system, as the true electronic ground state and mechanism behind the charge ordering transition has been controversial due to the still limited number of studies of this surface. A unique growth method is developed to grow larger domains on this surface, which greatly reduces the effects of defects and domain boundaries on the structure and electronic structure of the interface. This allows a comprehensive study of both the electronic and structural properties through quasiparticle interference imaging. To explore the role of spin-orbit coupling for heavy adatoms such as Pb, we introduced magnetic scattering centers (Mn) so as to break time-reversal symmetry in the QPI patterns. Our results provide clear evidence of Rashba-type spin-orbital coupling, although more detailed interpretation awaits further theoretical studies

Beyond “Respectability”: An Examination of the Discourse of Respect as Legitimacy as a Frame to Deny Truth and Immediacy to Silent Anti-Racist Protest

This thesis aims to illustrate the ways Black/Brown bodies are still widely and prolifically framed as sublegal and less legitimate, by examining the rhetorical racialized violence committed against persons of color who are considered to be the most respected and accepted by mainstream society; the respectables, Black/Brown academics and professional athletes. Simply put, my thesis is about using the way we respond to social movements as a lens to understanding the ways “colorblind” policies have failed in bridging our racial divide and have instead relocated the same problems under new terms. I will argue here that this does nothing more than create monuments for American chattel slavery and racial inequality within the minds of mainstream society. I contend that Black capture is ongoing and not past, and here I look to the racialized subjugation within academia and the NFL as microcosm and artifact that America is not the post-racial place it claims to be. It is a goal of this thesis to imagine solutions to our current racial divide and analyze the viability of current methods of challenging the status quo, such as political institutions and actors and social movements. I posit that intersectionality offers part of the solution, in that colorblind legislation and societal practices will be examined here by someone not of the majority disposition and world view, and with an entirely different identity composition than all the scholars presented here in this work. I also contend intersectionality can prove to be advantageous in allowing people of differing world views and experiences to view and examine the same information and offer different interpretations of the drawbacks and advantages of specific policy in order to minimize the amount of inequality that has been politely yet not unconsciously encoded into everyday life. This is a call to action to increase diversity not only in politics but academia as well, to signal a shift for accountability ensuring that no instance of whitewashing goes unchecked

Say Her Name: The Narrative Afterlives of Breonna Taylor

Within the growing literature and media coverage of police misconduct and brutality, Black women and girls are functionally invisible. Since the Black Lives Matter movement began the names of only two women have stood out among the Black male victims we know by name: Sandra Bland and Breonna Taylor. Here, I will explore through a Black feminist analytic framework, how the intersectionalities of gender and race contributed to a delay in awareness and accountability for the death of Breonna Taylor. This content analysis looked at the media coverage of Breonna Taylor for the one-year period (3/13/20-3/13/21) to uncover the reasons, implications, and usage of the resurrected story of Breonna Taylor following the death of George Floyd, to explain why her life and legacy only seems to matter because his did. The narrative afterlives of Breonna Taylor detail the implications of an empty activism; what happens when a name becomes the only thing we are saying? Secondarily, this thesis answers how and why she became the first Black woman martyred by the Black Lives Matter movement

Researching trust in the police and trust in justice: a UK perspective

This paper describes the immediate and more distant origins of a programme of comparative research that is examining cross-national variations in public trust in justice and in the police. The programme is built around a module of the fifth European Social Survey, and evolved from a study funded by the European Commission. The paper describes the conceptual framework within which we are operating – developed in large measure from theories of procedural justice. It reviews some of the methodological issues raised by the use of sample surveys to research issues of public trust in the police, public perceptions of institutional legitimacy and compliance with the law. Finally it gives a flavour of some of the early findings emerging from the programme

The modern use of the extended humeral head (cuff tear arthropathy) hemiarthroplasty.

Today, the treatment of osteoarthritis in the rotator cuff-deficient population is largely dominated by reverse shoulder arthroplasty (RSA). Despite the popularity of and increased familiarity with this procedure, the complication rate of RSA remains significant. An extended humeral head hemiarthroplasty may provide a less invasive alternative for select patients with cuff tear arthropathy (CTA) and preserved glenohumeral active elevation. With the indications for reverse arthroplasty expanding to younger patients, there are concerns about the longevity of this implant, as well as the associated revision burden. In the setting of failed RSA, the bone stock available for glenosphere baseplate fixation can be inadequate for reimplantation. The treatment strategies for complex shoulder deformities and failed RSA are limited by patient-specific issues, such as anatomy and risk factors. In this review, we discuss the potential role of extended humeral head hemiarthroplasty (CTA hemiarthroplasty) as a primary surgical option in select patients (1) who have preserved elevation \u3e 90°, (2) who have maintained stability (intact coracoacromial ligament), and (3) who desire to circumvent the complications associated with RSA. Furthermore, CTA hemiarthroplasty may be used for severe glenoid erosion, for a fragmented acromion, and in the revision setting for failed RSA aimed at a reliable salvage procedure

Analytical Modeling is Enough for High Performance BLIS

We show how the BLAS-like Library Instantiation Software (BLIS) framework, which provides a more detailed layering of the GotoBLAS (now maintained as OpenBLAS) implementation, allows one to analytically determine tuning parameters for high-end instantiations of the matrix-matrix multiplication. This is of both practical and scientific importance, as it greatly reduces the development effort required for the implementation of the level-3 BLAS while also advancing our understanding of how hierarchically layered memories interact with high-performance software. This allows the community to move on from valuable engineering solutions (empirically autotuning) to scientific understanding (analytical insight).This research was sponsored in part by NSF grants ACI-1148125/1340293 and CCF-0917167. Enrique S. Quintana-Ortí was supported by project TIN2011-23283 of the Ministerio de Ciencia e Innovacióon and FEDER. Francisco D. Igual was supported by project TIN2012-32180 of the Ministerio de Ciencia e Innovación

Modelling the costs and benefits of hybrid buses from a whole-life perspective

Hybrid electric-diesel engine technologies offer the potential to reduce fuel consumption in buses by around 40%. These savings can largely be attributed to regenerative braking – the ability to store in a battery energy that would otherwise have been lost under braking. Lower fuel consumption makes sense economically for bus operators through reduced running costs; hybrid engines have other wider benefits, though, such as reducing emissions and noise, and providing smoother acceleration and braking. The costs associated with hybrid technologies are significant, however, with hybrid vehicles currently costing around 50% more to buy than conventional buses. With Alexander Dennis and BAE Systems, UCL is conducting a three-year systems engineering research and development project to adapt and optimise hybrid buses for the UK and European market. This paper investigates one aspect of this project – the costs and benefits of introducing hybrid bus technologies from a whole-life perspective. We find that fuel and emissions savings alone do not provide a compelling case for hybrid buses based on current prices. However, as the cost of fuel rises, and when the social and environmental impacts of motor vehicle use are better accounted for, hybrid technology outperforms conventional diesel technology

When is policing fair? Groups, identity and judgements of the procedural justice of coercive crowd policing

Procedural justice theory (PJT) is now a widely utilised theoretical perspective in policing research that acknowledges the centrality of police ‘fairness’. Despite its widespread acceptance this paper asserts that there are conceptual limitations that emerge when applying the theory to the policing of crowd events. This paper contends that this problem with PJT is a result of specific assumptions that are highlighted by two studies using a novel experimental approach. Study 1 systematically manipulated the social categories used to describe crowd participants subjected to police coercion. The experiment demonstrates how these social categories dramatically affected participants’ perceptions of the same police action and that it was participants’ relational identification with the police, rather than a superordinate category, that mediated the association between judgements of procedural fairness and intentions to cooperate. In Study 2, using a quasi-experimental design, we then replicated and extended these findings by demonstrating how perceptions of procedural fairness are also influenced by levels of in-group identification. The paper concludes by exploring the implications of the data for reconceptualising the social psychological processes mediating these judgements and impacts of police legitimacy