Physical modelling of millimetre wave signal reflection from forward biased PIN diodes

This paper examines the DC power requirements of PIN diodes which, with suitable applied DC bias, have the potential to reflect or to permit transmission of millimetre wave energy through them by the process of inducing a semiconductor plasma layer in the i-region. The study is conducted using device level simulation of SOI and bulk PIN diodes and reflection modelling based on the Drude conduction model. We examined five diode lengths (60–140 µm) and seven diode thicknesses (4–100 µm). Simulation output for the diodes of varying thicknesses was subsequently used in reflection modelling to assess their performance for 100 GHz operation. It is shown that substantially high DC input power is required in order to induce near total reflection in SOI PIN diodes at 100 GHz. Thinner devices consume less DC power, but reflect less incident radiation for given input power. SOI diodes are shown to have improved carrier confinement compared with bulk diodes.

Reflection amplifier phase conjugation properties

The potential of employing a millimetre-wave MMIC reflection amplifier as a building block for a retrodirective reflectarray is investigated. With this in mind the phase conjugating behaviour of the device is experimentally quantified at 21 GHz.

Mid-infrared a-b plane response of YBa2Cu3O7-delta as a function of doping and temperature determined by attenuated total reflection

The mid-infrared optical response of c-axis thin films of YBa2Cu3O7-delta has been studied using Otto-configuration attenuated total reflectance. The measured reflectance-angle characteristics are dominated by a strong absorption feature due to the excitation of surface plasmons, and can be modeled to determine the a-b plane dielectric function. The results show that while epsilon(i,) and therefore sigma(r), are temperature independent, \epsilon(r)\ exhibits a moderate decrease with generalized Drude analysis shows that the plasma frequency is independent of temperature, but decreases with decreasing doping. The scattering rate increases with temperature, and also increases with decreasing doping, consistent with stronger coupling in the underdoped regime. The mass-enhancement is small but increases to 30-40% at delta = 0.6. Difficulties in reconciling the results with some current theories of high-T-c materials are discussed. Finally, the surface plasmon propagation lengths and penetration depths are shown to vary systematically with doping. (C) 2003 Elsevier B.V. All rights reserved.

Rethinking Amnesties: Atrocity, Accountability And Impunity In Post-Conflict Societies.

The notion of accountability that is propagated in transitional justice often appears limited to demands for the prosecution and imprisonment of those who have been involved in serious human rights violations. Amnesties, widely understood as the absence of punishment for wrongdoing, are in turn considered by many scholars and activists as an example par excellence of the kind of Faustian pacts which are made in the name of political expediency in transitions from conflict. Drawing from a range of interdisciplinary literature, as well as research completed by the authors in a number of societies with a violent past, this paper uses amnesties as a case-study to argue for a more rounded interrogation of the notion of accountability in transitional justice. The paper charts the various forms of intersecting accountability which both shape and delimit amnesties at key ‘moments’ concerning their remit, introduction and operation. The paper concludes that the legalistic view of amnesties as equating to impunity and retribution as accountability is inaccurate and misleading. It argues that a broader perspective of accountability speaks directly to the capacity for amnesties to play a more constructive role in post conflict justice and peacemaking.

Public Accountability: a critical approach

'Public Accountability' has been variously described as, for example, Chameleon-like, as everexpanding and as an iconic concept. Public accountability (PA) is a contested but fundamental concept in the structure of contemporary public services. However, much of the existing literature on PA can be seen as reductionist or managerialist. The experiences of public service-users rarely feature and certainly not in the context as a potential agent for change. A second related strand concerns the introduction of New Public Management (NPM) models, and their impact on accountability in the public sector. A central line of argument is that to overcome the reductionist approaches researchers need to place their work in the broad context of these changes. To that end, this paper sets out a critical conceptualisation of 'public accountability', where it is seen as a dynamic social relationship through which civil society seeks to control and challenge the state. This critical PA conceptualisation is then applied to the context of Social Housing in England. The analysis highlights key changes in the structure of accountability relationships, but also stresses the opposition that the reforms have generated. Finally, the conclusion draws links to the debates in the anti-capitalist movement as providing a source of possible research projects.

Understanding Accountability in Social Enterprise Organisations: A Framework

Purpose: Social enterprise organisations (SEOs) operate across the boundaries of the public, private and not‐for‐profit (NFP) sectors in delivering public services and competing for resources and legitimacy. While there is a rich literature on accountability in the private and public sectors, together with the wider NFP sector, SEOs have received comparatively little attention and remain a relatively under‐researched organisational form. Drawing on accountability, legitimacy and user‐needs theories, the purpose of this paper is to develop a practical framework which can be used to explore how accountability within SEOs is constructed and discharged.

Design/methodology/approach: This paper draws on user‐needs, accountability, legitimacy and impression management theories expounded in relation to the private, public and NFP sectors.

Findings: A framework to better understand how accountability can be discharged by SEOs is developed and discussed.

Research limitations/implications: While a framework for better understanding SEO accountability is presented, it is not empirically tested. However, the framework has the potential to facilitate a deeper appreciation of the theory and practice of accountability within SEOs and, notwithstanding the inherent difficulties in measuring and managing accountability, could be used to stimulate practitioner involvement.

Practical implications
– As little is known about the current extent of SEO information disclosure or accountability relationships, the framework could be used to assess the discharge of accountability by SEOs, with the findings informing future developments. This should provide useful insights into internal processes and organisational views on accountability bases and mechanisms and can then be used to inform the debate on how SEOs can best discharge their duty to account.

Social implications
– Understanding the nature of SEO accountability reporting has important implications for those involved in advancing the SEO agenda. At a time of public sector cutbacks, and with the government searching for new and more effective ways of delivering services, the role of SEOs in this process is likely to receive greater attention and scrutiny.

Originality/value
– SEOs have grown extensively in size and prominence in recent years and policymakers have come to embrace the role that they play in societal development. This paper responds to a gap in the theoretical literature and contributes to the debate by developing a framework which can be empirically tested. Moreover, it can be used to prompt practitioner involvement and facilitate a better understanding of the complex issues surrounding accounting and accountability in this under‐researched area.

Discharging not-for-profit accountability: UK charities and public discourse

Purpose: This paper aims to examine the accountability practices of large United Kingdom (UK) charities through public discourse.
Design/methodology/approach: Based on the ethical model of stakeholder theory, the paper develops a framework for classifying not-for-profit (NFP) accountability and analyzes the content of the annual reports and annual reviews of a sample of large UK charities using this framework.
Findings: The results suggest that contrary to the ethical model of stakeholder theory, the sample charities’ accountability practices are motivated by a desire to legitimize their activities and present their organizations’ activities in a positive light. These results contradict the raison d’eˆ tre of NFP organizations (NFPOs) and the values that they espouse. Research limitations/implications: Understanding the nature of accountability reporting in NFPOs has important implications for preparers and policy makers involved in furthering the NFP agenda. New research needs to examine shifts in accountability practices over time and assess the impact of the recent self-regulation developed to enhance sector accountability.
Originality/value: This paper contributes to the NFP accountability literature by: first, developing a framework of NFP accountability through public discourse using the ethical model of stakeholder theory; and second, advancing the understanding of the accountability practices of large UK charities.