Gauge Mediation in Metastable Vacua

Until recently, dynamical supersymmetry breaking seemed an exceptional phenomenon, involving chiral gauge theories with a special structure. Recently it has become clear that requiring only metastable states with broken supersymmetry leads to a far broader class of theories. In this paper, we extend these constructions still further, finding new classes which, unlike earlier theories, do not have unbroken, approximate $R$ symmetries. This allows construction of new models with direct gauge mediation. These theories permit a relatively compact solution to the $\mu$ problem.Comment: 11 pages, latex. Issues of metastability further elaborate

Research on Europa's dust cloud at The Open University's HVI Laboratory

Space in the vicinity of Europa is populated by dust originating from its surface. Fragments of the surface are ejected due to meteroid hypervelocity impacts (but also they may originate from the sub-surface such as was found on Enceladus). It is assumed that orbit-based detection and analysis of material ejected from the Europan Surface may provide an alternative method for sampling Europan material without landing on the surface. Rleative impact speeds from these dust sources onto an in-orbit detector would, typically, be about 2 kms.This impact speed is generally too low for complete vapourisation of the impactor/target and the ejecta material could be caputured in-situ for further analysis. Our current work is aimed at the development of a new hybrid dust detector for any Europa orbiter as well as an understanding of Europa's dust cloud by mimicing micrometeoroid impact into simulated European regolith/ice. In this paper we present our latest research as well as the caility we have developed as a new laboratory in the filed of HVI physics

Dosimetry in mixed radiation fields

Imperial Users onl

Evaluating change in professional behaviour: issues in design and analysis

Implementing the findings of research to change the behaviour of health care professionals has become an increasingly prominent issue. However, designing valid studies to evaluate different methods of achieving changes requires considerable care and there are a number of pitfalls evident from published previous work. The various steps in the development of an implementation method and issues arising are explored in this text. Aspects include conceptualisation, essential background work, a structured development process, the relative merits of randomised and non-equivalent group designs, the unit of analysis, the role of multi-level models, block designs, economic analysis, and the content or message to be disseminated. An ongoing, large, randomised trial of educational outreach visits by trained pharmacists is used to illustrate some of the issues.behavioural change, implementation methods, economic evaluation, design of trials

Dynamical Supersymmetry Breaking and Low Energy Gauge Mediation

Dynamical breaking of supersymmetry was long thought to be an exceptional phenomenon, but recent developments have altered this view. A question of great interest in the current framework is the value of the underlying scale of supersymmetry breaking. The "little hierarchy" problem suggests that supersymmetry should be broken at low energies. Within one class of models, low energy breaking be achieved as a consequence of symmetries, without requiring odd coincidences. The low energy theories are distinguished by the presence or absence of $R$ symmetries; in either case, and especially the latter one often finds modifications of the minimal gauge-mediated spectrum which can further ameliorate problems of fine tuning. Various natural mechanisms exist to solve the $\mu$ problem in this framework.Comment: 20 pages (minor change in referencing

La incitación al estudiante para que use su capacidad natural de expresar generalidad: las secuencias de Tunja

La conjetura que se promueve en este artículo es que la detección de patrones y la expresión de generalidad están en el centro de las matemáticas; sin duda, el estudio de las matemáticas puede ayudar a desarrollar y a refinar las capacidades naturales para ello en la mayoría de los estudiantes. En el contexto de desarrollar expresiones con paréntesis y factorizar expresiones cuadráticas se presentan ejemplos de cómo incitar a los estudiantes para que lo hagan usando sus capacidades en lugar de atenerse al maestro o al libro. En el corazón de este enfoque está la conjetura de que los estudiantes que tienen una historia en detectar y expresar generalidad explícitamente en la clase de matemáticas llegarán al álgebra con una mente completamente diferente porque las expresiones que se espera que ellos manipulen, desarrollen y factoricen son vistas por los estudiantes como la expresión de una generalidad hecha por alguien y no sólo como cálculos carentes de significado con letras que no tienen sentido

Hendrik Albertus and his ex-slave Mey: A drama in three acts

African Studies Seminar series. Paper presented August 1989In the early spring of 1832, Mey, a slave belonging to Hendrik Albertus van Niekerk, initiated a series of events that, in quick succession, saw him beaten by his master's son, Hendrik, Jr., whipped again by his master's own hand, and unconditionally freed by old Hendrik barely ten days later. It is a remarkable story, probably without parallel in the history of the Cape Colony, and worth telling if only for that reason. But the story also deserves the historian's attention because in determining why events passed as they did, some light can be shed on previously obscure areas of South African history