Near-field coupling and resonant cavity modes in plasmonic nanorod metamaterials

Plasmonic resonant cavities are capable of confining light at the nanoscale, resulting in both enhanced local electromagnetic fields and lower mode volumes. However, conventional plasmonic resonant cavities possess large Ohmic losses at metal-dielectric interfaces. Plasmonic near-field coupling plays a key role in a design of photonic components based on the resonant cavities because of the possibility to reduce losses. Here, we study the plasmonic near-field coupling in the silver nanorod metamaterials treated as resonant nanostructured optical cavities. Reflectance measurements reveal the existence of multiple resonance modes of the nanorod metamaterials, which is consistent with our theoretical analysis. Furthermore, our numerical simulations show that the electric field at the longitudinal resonances forms standing waves in the nanocavities due to the near-field coupling between the adjacent nanorods, and a new hybrid mode emerges due to a coupling between nanorods and a gold-film substrate. We demonstrate that this coupling can be controlled by changing the gap between the silver nanorod array and gold substrate.

Self-cutting and prospective repetition of self-harm: studies of emergency department presentations in Ireland

Background Self-harm places an individual at increased risk of future self-harm and suicide, and indicates distress and maladaptive coping. Those who present to hospital with self-cutting form a significant minority of self-harm patients who are at increased risk of prospective repetition of self-harm and suicide compared with those presenting with intentional overdose. In addition to increased risk, there is emerging evidence of demographic, psychological, clinical, and social differences between those presenting with self-cutting and those presenting with overdose. Aim and Key Objectives The aim of the current doctoral work was to examine in detail the association between presenting with self-cutting and risk of prospective repetition. The objectives were: to identify evidence-based risk factors for repetition of self-harm among those presenting to emergency departments with self-harm; to compare demographic and presentation characteristics and prospective repetition across presentations of self-cutting only, self-cutting plus intentional overdose, and intentional overdose only; to compare prospective repetition and other characteristics within self-cutting presentations based on the type of treatment received; to compare self-cutting and intentional overdose patients on psychological risk and protective factors for repetition; and to examine the lived experience of engaging in repeated overdose and self-cutting. Methods The current doctoral work used a mixed-methods approach and is comprised of one systematic review and four empirical studies. The empirical studies were two registry-based prospective studies of Irish hospital presentations of self-harm, one prospective structured interview study, and one qualitative study using Interpretative Phenomenological Analysis. Results The systematic review identified several consistent and emerging risk factors for repetition of self-harm, compared to which self-cutting had a medium-sized effect. The registry studies demonstrated that the involvement of self-cutting, particularly less medically severe selfcutting, confers an increased risk of 1-month and 12-month repetition among Irish index selfharm presentations. The structured psychological study detected higher hopelessness and lower non-reactivity to inner experience among those presenting with self-cutting, and higher depression among those who repeated self-harm. Repeaters had lower baseline levels of protective psychological factors than non-repeaters and continued to have higher depression and hopelessness at follow-up. Finally, the qualitative study indicated that self-harm is a purposeful action taken in response to an overwhelming situation and is evaluated afterwards in terms of personal and social effects. Chosen method of self-harm seemed to be influenced by the desired outcome of the self-harm act, capability, accessibility and previous experience. Conclusion Despite limitations in terms of recruitment rates, the work presented in this thesis is innovative in examining the issue of the association between self-cutting and repetition from multiple perspectives. No one factor can reliably predict all repetition but self-cutting represents one consistent and easily detected risk factor for repetition. Those who present with self-cutting exhibit significant differences on demographic, clinical, and psychological variables compared with those presenting with intentional overdose, and seem to exhibit a more vulnerable profile. However, those who present with self-cutting do not form a discrete or homogenous group, and self-harm methods and levels of suicidal intent are liable to fluctuate over time.

Study of the kinetics and mechanism of rapid self-assembly in block copolymer thin films during solvo-microwave annealing

Microwave annealing is an emerging technique for achieving ordered patterns of block copolymer films on substrates. Little is understood about the mechanisms of microphase separation during the microwave annealing process and how it promotes the microphase separation of the blocks. Here, we use controlled power microwave irradiation in the presence of tetrahydrofuran (THF) solvent, to achieve lateral microphase separation in high- lamellar-forming poly(styrene-b-lactic acid) PS-b-PLA. A highly ordered line pattern was formed within seconds on silicon, germanium and silicon on insulator (SOI) substrates. In-situ temperature measurement of the silicon substrate coupled to condition changes during "solvo-microwave" annealing allowed understanding of the processes to be attained. Our results suggest that the substrate has little effect on the ordering process and is essentially microwave transparent but rather, it is direct heating of the polar THF molecules that causes microphase separation. It is postulated that the rapid interaction of THF with microwaves and the resultant temperature increase to 55 degrees C within seconds causes an increase of the vapor pressure of the solvent from 19.8 to 70 kPa. This enriched vapor environment increases the plasticity of both PS and PLA chains and leads to the fast self-assembly kinetics. Comparing the patterns formed on silicon, germanium and silicon on insulator (SOI) and also an in situ temperature measurement of silicon in the oven confirms the significance of the solvent over the role of substrate heating during "solvo-microwave" annealing. Besides the short annealing time which has technological importance, the coherence length is on a micron scale and dewetting is not observed after annealing. The etched pattern (PLA was removed by an Ar/O-2 reactive ion etch) was transferred to the underlying silicon substrate fabricating sub-20 nm silicon nanowires over large areas demonstrating that the morphology is consistent both across and through the film.

Numerical detection of the Gardner transition in a mean-field glass former.

Recent theoretical advances predict the existence, deep into the glass phase, of a novel phase transition, the so-called Gardner transition. This transition is associated with the emergence of a complex free energy landscape composed of many marginally stable sub-basins within a glass metabasin. In this study, we explore several methods to detect numerically the Gardner transition in a simple structural glass former, the infinite-range Mari-Kurchan model. The transition point is robustly located from three independent approaches: (i) the divergence of the characteristic relaxation time, (ii) the divergence of the caging susceptibility, and (iii) the abnormal tail in the probability distribution function of cage order parameters. We show that the numerical results are fully consistent with the theoretical expectation. The methods we propose may also be generalized to more realistic numerical models as well as to experimental systems.

CEO Humility: Development of an Unobtrusive Measure and Strategic Implications

Over the past 30 years, the Upper Echelons perspective of strategic management has sought to explain a given organization’s strategies and effectiveness as a reflection of the differences in personality, background, and other characteristics of the senior executives that guides each organization. An important stream of research within this field has linked a firm’s strategy to the grandiose way that executives are often thought to view themselves – namely through examining the narcissism, core self-evaluations (CSE), and hubris of Chief Executive Officers (CEOs). In this dissertation, I focus on understanding the strategic impact of CEO humility – a trait that has often been erroneously thought of to represent a poor view of oneself. Consistent with ancient writings and recent research, humility is defined herein as a multi-faceted trait that is the common core of four dimensions: self-awareness, developmental orientation/teachability, appreciation of others' strengths and contributions, and low self-focus. In the first essay, I explore the conceptual relevance and various potential implications of executive humility. Drawing on existing empirical research about the humility construct and general behavioral implications of humility, I argue that executive humility is a critical avenue toward a more rich and nuanced understanding of the delicate interplay and implications of executive self-concept. In essay two, I develop and validate an unobtrusive measure of CEO humility. Ten indicators of humility are suggested and then validated using a self-reported survey administered to a sample of 30 U.S. and Canadian CEOs. Two behaviors were found to be significantly positively related to self-reported humility: CEOs who volunteered some of their time for non-profit organizations and CEO’s who reported that part of their own firm’s success was due to the help of the board of directors. In essay three, I examine the relationship between the level of CEO humility and four firm-level outcomes. Employing a sample of 163 CEOs appointed to S&P 500 firms between 2005-2008, I show that firms led by humble CEOs (measured by the unobtrusive indicators) tend to outperform others in regards to corporate social performance, while at the same time showing that their financial performance is generally no better or worse.

The Rotational Evolution and Magnetospheric Emission of the Magnetic Early B-type Stars

How do the magnetic fields of massive stars evolve over time? Are their gyrochronological ages consistent with ages inferred from evolutionary tracks? Why do most stars predicted to host Centrifugal Magnetospheres (CMs) display no H$\alpha$ emission? Does plasma escape from CMs via centrifugal breakout events, or by a steady-state leakage mechanism? This thesis investigates these questions via a population study with a sample of 51 magnetic early B-type stars. The longitudinal magnetic field \bz~was measured from Least Squares Deconvolution profiles extracted from high-resolution spectropolarimetric data. New rotational periods $P_{\rm rot}$ were determined for 15 stars from \bz, leaving only 3 stars for which $P_{\rm rot}$ is unknown. Projected rotational velocities \vsini~were measured from multiple spectral lines. Effective temperatures and surface gravities were measured via ionization balances and line profile fitting of H Balmer lines. Fundamental physical parameters, \bz, \vsini, and $P_{\rm rot}$ were then used to determine radii, masses, ages, dipole oblique rotator model, stellar wind, magnetospheric, and spindown parameters using a Monte Carlo approach that self-consistently calculates all parameters while accounting for all available constraints on stellar properties. Dipole magnetic field strengths $B_{\rm d}$ follow a log-normal distribution similar to that of Ap stars, and decline over time in a fashion consistent with the expected conservation of fossil magnetic flux. $P_{\rm rot}$ increases with fractional main sequence age, mass, and $B_{\rm d}$, as expected from magnetospheric braking. However, comparison of evolutionary track ages to maximum spindown ages $t_{\rm S,max}$ shows that initial rotation fractions may be far below critical for stars with $M_*>10 M_\odot$. Computing $t_{\rm S,max}$ with different mass-loss prescriptions indicates that the mass-loss rates of B-type stars are likely much lower than expected from extrapolation from O-type stars. Stars with H$\alpha$ in emission and absorption occupy distinct regions in the updated rotation-magnetic confinement diagram: H$\alpha$-bright stars are found to be younger, more rapidly rotating, and more strongly magnetized than the general population. Emission strength is sensitive both to the volume of the CM and to the mass-loss rate, favouring leakage over centrifugal breakout.

THE ELEMENTARY TEACHERS’ PERCEPTIONS OF MOTIVATION FOR AND THE PRINCIPAL’S INFLUENCE ON THEIR ENGAGEMENT IN SELF-DIRECTED PROFESSIONAL DEVELOPMENT

All teachers participate in self-directed professional development (PD) at some point in their careers; however, the degree to which this participation takes place varies greatly from teacher to teacher and is influenced by the leadership of the school principal. The motivation behind why teachers choose to engage in PD is an important construct. Therefore, there is a need for better understanding of the leader’s role with respect to how and why teachers engage in self-directed professional development. The purpose of the research was to explore the elementary teachers’ motivation for and the school principal’s influence on their engagement in self-directed professional development. Three research questions guided this study: 1. What motivates teachers to engage in self-directed professional development? 2. What are the conditions necessary for promoting teachers’ engagement in self-directed professional development? 3. What are teachers’ perceptions of the principal’s role in supporting, fostering, encouraging, and sustaining the professional development of teachers? A qualitative research approach was adopted for this study. Six elementary teachers from one south-eastern Ontario school board, consisting of three novice and three more experienced teachers, provided their responses to a consistent complement of 14 questions. Their responses were documented via individual interviews, transcribed verbatim, and thematically analysed. The findings suggested that, coupled with the individual motivating influences, the culture of the school was found to be a conditional dynamic that either stimulated or dissuaded participation in self-directed PD. The school principal provided an additional catalyst or deterrence via relational disposition. When teachers felt their needs for competency, relatedness, and autonomy were satisfied, the conditions necessary to motivate teachers to engage in PD were fulfilled. A principal who personified the tenets of transformational leadership served to facilitate teachers’ inclinations to take on PD. A leadership style that was collaborative and trustful and allowed for personal autonomy was a dominant foundational piece that was critical for participant participation in self-directed PD. Finally, the principals were found to positively impact school climate by partaking in PD alongside teachers and ensuring there was a shared vision of the school so that teachers could tailor PD to parallel school interests.

Celebrity Capital in the Political Field: Russell Brand’s migration from stand-up comedy to Newsnight

Our case study of charismatic celebrity comedian Russell Brand’s turn to political activism uses Bourdieu’s field theory to understand the process of celebrity migration across social fields. We investigate how Brand’s capital as a celebrity performer, storyteller and self-publicist translated from comedy to politics. To judge how this worked in practice, we analysed the comedic strategies used in his stand-up show Messiah Complex and undertook a conversational analysis of his notorious interview with Jeremy Paxman on the British Broadcasting Corporation (BBC)’s flagship current affairs programme Newsnight. We argue that Brand was able to secure political legitimacy by creatively constituting himself as an authentic anti-austerity spokesperson for the disenfranchised left in United Kingdom. In order to do so, he repurposed his celebrity capital to political ends and successfully deployed the cultural and social capitals he had developed as a celebrity comedian to secure widespread engagement with his media performances.

Self-assessments of memory correlate with neuroticism and conscientiousness, not memory span performance

Self-report measures of cognitive problems may have value, but there are indications that scores on such measures are influenced by other factors such as personality. In an online correlational study, 523 non-clinical volunteers completed measures of personality, digit span, and the Prospective and Retrospective Memory Questionnaire. Self-reported prospective and retrospective memory failures were associated positively with neuroticism and negatively with conscientiousness, but not with digit span performance. These findings are consistent with other indications that conscientiousness and neuroticism may underpin self-reports of cognitive problems.

Dynamic control of laser driven proton beams by exploiting self-generated, ultrashort electromagnetic pulses

As part of the ultrafast charge dynamics initiated by high intensity laser irradiations of solid targets,high amplitude EM pulses propagate away from the interaction point and are transported along anystalks and wires attached to the target. The propagation of these high amplitude pulses along a thinwire connected to a laser irradiated target was diagnosed via the proton radiography technique,measuring a pulse duration of 20 ps and a pulse velocity close to the speed of light. The strongelectric field associated with the EM pulse can be exploited for controlling dynamically the protonbeams produced from a laser-driven source. Chromatic divergence control of broadband laser drivenprotons (upto 75% reduction in divergence of >5 MeV protons) was obtained by winding the supportingwire around the proton beam axis to create a helical coil structure. In addition to providingfocussing and energy selection, the technique has the potential to post-accelerate the transiting protonsby the longitudinal component of the curved electric field lines produced by the helical coil lens.

Magnetic field generation during intense laser channelling in underdense plasma

Channel formation during the propagation of a high-energy (120 J) and long duration (30 ps) laser pulse through an underdense deuterium plasma has been spatially and temporally resolved via means of a proton imaging technique, with intrinsic resolutions of a few micron and a few ps, respectively. Conclusive proof is provided that strong azimuthally symmetric magnetic fields with a strength of around 0.5 MG are created inside the channel, consistent with the generation of a collimated beam of
relativistic electrons. The inferred electron beam characteristics may have implications for the cone-free fast-ignition scheme of inertial confinement fusion

Self-perceptions of the role of the planner

The role of the planning practitioner has received considerable attention in a diverse range of theoretical and empirical debates within the broad spectrum of planning scholarship from normative debates surrounding the planner's role in society, to more empirical investigations into the skills, attributes, and evolving nature of planning practitioners. Fundamental questions surrounding the role and purpose of planners have also entered into more mainstream discussions as the democratic nature of the planning system has been consistently undermined by allegations of misconduct, corruption, and incompetence. Despite the broad range of literature and debate which centres on the role of the planner, relatively few studies have explored the views of planning practitioners themselves, making it difficult to judge whether the ideas of planning academics are actually shared by those in the field. In this paper we seek to address this particular gap and argue that such insights are critical in determining the extent to which planning practitioners serve to challenge, maintain, or reinforce existing power imbalances in the planning system. The methodology consists of a series of qualitative interviews with twenty local authority planners working throughout the Greater Dublin Area, Ireland. The results suggest that planners' self-perceptions of their role tend to reflect traditional pluralist and managerialist perspectives. More broadly, the results suggest that the role orientations of contemporary planners are being shaped by dominant discourses in current planning ideology — namely, collaborative and participatory approaches

New developmental stages for common marmosets (Callithrix jacchus) using mass and age variables obtained by K-means algorithm and self-organizing maps (SOM)

LEÃO, Adriano de Castro; DÓRIA NETO, Adrião Duarte; SOUSA, Maria Bernardete Cordeiro de. New developmental stages for common marmosets (Callithrix jacchus) using mass and age variables obtained by K-means algorithm and self-organizing maps (SOM). Computers in Biology and Medicine, v. 39, p. 853-859, 2009

Dynamics of coupled modes in two-section semiconductor lasers with saturable absorption

Semiconductor lasers have the potential to address a number of critical applications in advanced telecommunications and signal processing. These include applications that require pulsed output that can be obtained from self-pulsing and mode-locked states of two-section devices with saturable absorption. Many modern applications place stringent performance requirements on the laser source, and a thorough understanding of the physical mechanisms underlying these pulsed modes of operation is therefore highly desirable. In this thesis, we present experimental measurements and numerical simulations of a variety of self-pulsation phenomena in two-section semiconductor lasers with saturable absorption. Our theoretical and numerical results will be based on rate equations for the field intensities and the carrier densities in the two sections of the device, and we establish typical parameter ranges and assess the level of agreement with experiment that can be expected from our models. For each of the physical examples that we consider, our model parameters are consistent with the physical net gain and absorption of the studied devices. Following our introductory chapter, the first system that we consider is a two-section Fabry-Pérot laser. This example serves to introduce our method for obtaining model parameters from the measured material dispersion, and it also allows us to present a detailed discussion of the bifurcation structure that governs the appearance of selfpulsations in two-section devices. In the following two chapters, we present two distinct examples of experimental measurements from dual-mode two-section devices. In each case we have found that single mode self-pulsations evolve into complex coupled dualmode states following a characteristic series of bifurcations. We present optical and mode resolved power spectra as well as a series of characteristic intensity time traces illustrating this progression for each example. Using the results from our study of a twosection Fabry-Pérot device as a guide, we find physically appropriate model parameters that provide qualitative agreement with our experimental results. We highlight the role played by material dispersion and the underlying single mode self-pulsing orbits in determining the observed dynamics, and we use numerical continuation methods to provide a global picture of the governing bifurcation structure. In our concluding chapter we summarise our work, and we discuss how the presented results can inform the development of optimised mode-locked lasers for performance applications in integrated optics.

Afrofuturism as Applied to Self-Perception: an Experimental Vignette Study

Thesis (Master's)--University of Washington, 2016-06