Development of opto-mechanical tools and procedures for the new generation of RICH-detectors at CERN

This thesis is focused on development of opto-mechanical tools and procedures, which would contribute to the achievement of the best possible performance of new Ring Imaging Cherenkov (RICH) detectors. On the base of requirements, given by the physics objective of the LHCb detector, and an analysis of the detector opto-mechanical system, specifications of individual opto-mechanical components were determined. Spherical mirrors, planar mirrors and mirror adjustable mounts were the components of interest. Next, their parameters to be characterised were defined. Possible measurement methods were studied and relevant set ups based on suitable methods were developed. Meanwhile, available modern metrology technologies, like laser operated instruments or digital image processing, were applied with an attempt to innovate them and to increase their achievable performance limits. When applicable, the set ups were automated in order to make the measurements fast and reliable. An optical laboratory, devoted to the characterisation of the RICH opto-mechanical components, was established. Collaboration with industry was started. A number of prototypes of mirrors and of mirror mounts for both the LHCb and COMPASS RICH detectors was tested, and a feedback to manufacturers was provided. The quality of the whole production of the COMPASS RICH 1 mirrors was tested. The laboratory and its facilities are being applied for optimisation of the LHCb RICH opto-mechanical component parameters and they will be used for the quality tests of the final products

Analysis techniques for multivariate root loci

Analysis and techniques are developed for the multivariable root locus and the multivariable optimal root locus. The generalized eigenvalue problem is used to compute angles and sensitivities for both types of loci, and an algorithm is presented that determines the asymptotic properties of the optimal root locus

Boltzmann and hydrodynamic description for self-propelled particles

We study analytically the emergence of spontaneous collective motion within large bidimensional groups of self-propelled particles with noisy local interactions, a schematic model for assemblies of biological organisms. As a central result, we derive from the individual dynamics the hydrodynamic equations for the density and velocity fields, thus giving a microscopic foundation to the phenomenological equations used in previous approaches. A homogeneous spontaneous motion emerges below a transition line in the noise-density plane. Yet, this state is shown to be unstable against spatial perturbations, suggesting that more complicated structures should eventually appear.Comment: 4 pages, 3 figures, final versio

Photonic band-gap properties for two-component slow light

We consider two-component "spinor" slow light in an ensemble of atoms coherently driven by two pairs of counterpropagating control laser fields in a double tripod-type linkage scheme. We derive an equation of motion for the spinor slow light (SSL) representing an effective Dirac equation for a massive particle with the mass determined by the two-photon detuning. By changing the detuning the atomic medium acts as a photonic crystal with a controllable band gap. If the frequency of the incident probe light lies within the band gap, the light tunnels through the sample. For frequencies outside the band gap, the transmission probability oscillates with increasing length of the sample. In both cases the reflection takes place into the complementary mode of the probe field. We investigate the influence of the finite excited state lifetime on the transmission and reflection coefficients of the probe light. We discuss possible experimental implementations of the SSL using alkali atoms such as Rubidium or Sodium.Comment: 7 figure

Detection of ubiquityl-calmodulin conjugates with a novel high-molecular weight ubiquitylprotein-isopeptidase in rabbit tissues

The selective degradation of many proteins in eukaryotic cells is carried out by the ubiquitin system. In this pathway, proteins are targeted for degradation by covalent ligation to ubiquitin, a highly conserved protein [1]. Ubiquitylated proteins were degraded by the 26S protea-some in an ATP-depended manner. The degradation of ubiquitylated proteins were controlled by isopeptidase cleavage. A well characterised system of ubiquitylation and deubiquitylation is the calmodulin system in vitro [2]. Detection of ubiquityl-calmodulin conjugtates in vivo have not been shown so far. In this article we discuss the detection of ubiquitin calmodulin conjugates in vivo by incubation with a novel high-molecular weight ubiquitylprotein-isopeptidase in rabbit tissues. Proteins with a molecular weight of ubiquityl-calmodulin conjugates could be detected in all organs tested. Incubation with ubiquitylprotein-isopeptidase showed clearly a decrease of ubiquitin calmodulin conjugates in vivo with an origination of unbounded ubiquitin. These results suggest that only few ubiquitin calmodulin conjugates exist in rabbit tissues

Airloads on bluff bodies, with application to the rotor-induced downloads on tilt-rotor aircraft

The aerodynamic characteristics of airfoils with several flap configurations were studied theoretically and experimentally in environments that simulate a wing immersed in the downwash of a hovering rotor. Special techniques were developed for correcting and validating the wind tunnel data for large blockage effects, and the test results were used to evaluate two modern blockage effects, and the test results were used to evaluate two modern computational aerodynamics codes. The combined computed and measured results show that improved flap and leading-edge configurations can be designed which will achieve large reductions in the downloads of tilt-rotor aircraft, and thereby improve their hover efficiency

Onset of collective and cohesive motion

We study the onset of collective motion, with and without cohesion, of groups of noisy self-propelled particles interacting locally. We find that this phase transition, in two space dimensions, is always discontinuous, including for the minimal model of Vicsek et al. [Phys. Rev. Lett. {\bf 75},1226 (1995)] for which a non-trivial critical point was previously advocated. We also show that cohesion is always lost near onset, as a result of the interplay of density, velocity, and shape fluctuations.Comment: accepted for publication in Phys. Rev. Let

Characteristics of schools with and without Gay-Straight Alliances

Research shows that Gay-Straight Alliances (GSAs) are associated with school climate and student well-being, but it is unclear what school characteristics may account for some of these findings. The current study describes characteristics of schools with and without GSAs. Using a population-based sample of 1,360 California public high schools, inferential statistics show that schools with larger enrollment, more experienced teachers, and lower pupil/teacher ratios were more likely to have GSAs. In addition, among schools with GSAs, larger enrollment, more experienced teachers, fewer socioeconomically disadvantaged students, and higher academic achievement are among the factors related to a longer presence of GSAs. Implications for GSA and policy implementation, as well as the importance of accounting for school characteristics in research on GSAs are discussed

Youth Empowerment and High School Gay-Straight Alliances

In the field of positive youth development programs, “empowerment” is used interchangeably with youth activism, leadership, civic participation and self-efficacy. However, few studies have captured what empowerment means to young people in diverse contexts. This article explores how youth define and experience empowerment in youth-led organizations characterized by social justice goals: high school Gay-Straight Alliances (GSAs). Through focus group interviews, fifteen youth leaders of GSAs from different regions of California explain what they think empowerment means and how they became empowered through their involvement with the GSA. Youth describe three inter-related dimensions of empowerment: personal empowerment, relational empowerment, and strategic empowerment through having and using knowledge. When these three dimensions are experienced in combination, GSA leaders have the potential for individual and collective empowerment as agents of social change at school. By understanding these youth\u27s perspectives on the meanings of empowerment, this article clarifies the conceptual arena for future studies of socially marginalized youth and of positive youth development

Austerity-driven policification: neoliberalisation, schools, and the police in Britain

This article argues that as a consequence of austerity, police in England and Wales have taken over important roles in welfare and social policy institutions. This renders those institutions more coercive, punitive, and exclusionary, and normalises a police world view in those institutions. This process of what I call austerity-driven policification (Cf. Millie, 2013) can be observed specifically well in the increasing numbers of police officers integrated into schools most affected by austerity (Henshall, 2018; Joseph-Salisbury, 2021; Laub, 2021; Nijjar, 2021). Such ‘transinstitutional policing’ (Patel, forthcoming) in Britain is triggered by contradictory post-global financial crisis (GFC) austerity measures, but reliant upon a long, racialised history of authoritarian neoliberalisation. Cuts to public spending in the 2010s reduced state institutions’ capacities to provide for vulnerable people who were further criminalised and whose rights to support and solidarity were further delegitimised by a radicalisation of the framing of welfare recipients as undeserving, social housing estates as drug-infested gang territories, and schools in deprived areas and Black pupils in particular, as dangerous. Police, while subjected to austerity measures also, functioned as an institution of last resort, supplementing and replacing incapacitated state institutions, while also being presented as an appropriate institution to address problems increasingly understood to be of a criminal rather than educational nature. This article suggests that austerity-driven policification is an intensification of longer-term trends toward a larger role for police in the neoliberal era. It shows the racial and authoritarian nature of neoliberalisation, and its messy realisation