Four K refrigerators with a new compact heat exchanger

Two refrigerators have been developed which have nominal cpacities of 0.25M and 0.5W at 4.2K. These use standard two stage Displex sup R expanders and compressors combined with a new compact heat exchanger which is concentric with the expander cylinder. These refrigerators can be used to cool superconducting electronic devices by direct attachment to the 4K heat station, or they can be plugged into the neck of a liquid helium superconducting magnet cryostat where they can cool the radiation shields and reliquefy helium

LEADERSHIP IN THE VIRTUAL HIGHER EDUCATION SECTOR: Is there a new way to lead in the on-line distance learning environment?

The growth in e-learning and other distance modes of delivery in the higher education sector, the explosion in borderless higher education and the marketisation of higher education, pose a challenge to the traditionally characteristic structures of decision making and consensual leadership in Higher Education. The paper seeks to examine if there is significant difference between leadership in the traditional Higher Education (HE) environment and leadership in the virtual HE environment by examining the framework of leadership models taken from the business literature - transformational and transactional leadership as well as the newer forms of leadership models such as servant leadership and distributed leadership. The models are applied to the case of an emerging virtual arm of a traditional university. The analysis suggests that the virtual higher education institution requires a complex repertoire of leadership skills and abilities but the process of leadership strongly suggests a dispersed or distributed approach

Three-stage linear, split-Stirling cryocooler for 1 to 2K magnetic cold stage

A long-life, linear, high efficiency 8K split Stirling cycle cryocooler was designed, built, and tested. The refrigerator is designed for cooling a 50 mW, 1.5K magnetic cold stage. Dual opposed piston compressors are driven by moving-coil linear motors. The three stage expander, although not completed, is also driven by a linear motor and is designed to produce 1 SW at 60K, 4W at 16K, and 1.2W at 8K. The cold regenerator employs a parallel gap construction for high efficiency. The key technology areas addressed include warm and cold flexible suspension bearings and a new cold regenerator geometry for high efficiency at 8K

When hot water freezes before cold

I suggest that the origin of the Mpemba effect (the freezing of hot water before cold) is freezing-point depression by solutes, either gaseous or solid, whose solubility decreases with increasing temperature so that they are removed when water is heated. They are concentrated ahead of the freezing front by zone refining in water that has not been heated, reduce the temperature of the freezing front, and thereby reduce the temperature gradient and heat flux, slowing the progress of the front. I present a simple calculation of this effect, and suggest experiments to test this hypothesis.Comment: 7 pages, 1 figur

Leadership in the Virtual Higher Education Environment: Towards an Appropriate Model and Framework

Research into leadership in the higher education environment has traditionally mirrored business related constructs. Many of the models and instruments that have been developed for the business environment such as the transactional transformational leadership dyad have been transposed to the higher education environment with relatively minor adaptation. On the other hand, there has been relatively little exploration of leadership models for the Virtual Organisation. This research brings together the literatures of virtuality and the virtual organisation, leadership and higher education management to interrogate the effect of virtuality on leadership styles within the volatile global higher education environment caused by the liberalisation of the sector. Through a case study of a higher education institution (HEI) that is developing a virtual campus, the research explores the perceptions of leadership skills, competencies and behaviours within the virtual higher education environment to determine whether a new model or framework can be developed for a virtual and widely distributed environment. The data from interviews, surveys and focus groups carried out in the case study show that virtuality does impact leadership skills in nuanced ways, thus proposing a configuration of behaviours, skills and competencies more relevant to the virtual higher education environment. The proposed framework adds to the literature on leadership in higher education as well as leadership in the virtual environment and contributes to practice in the areas of recruitment and training of leaders and managers in the virtual higher education sector.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Activist leadership in the Caribbean : The case of the University of the West Indies

This chapter investigates how a cross-national university (the University of the West Indies), in a transitional region such as the Caribbean, implements its third mission. We employ a broad understanding of the third mission as engagement in society including entrepreneurial and innovative efforts. Drawing on the entrepreneurial architecture framework, the chapter discusses how systems, structures, strategy, leadership, and culture form a unique mandate to engage in national, regional, but also international challenges.publishedVersio

The Driving Effects of Common Atmospheric Molecules for Formation of Clusters: the Case of Sulfuric Acid, Formic Acid, Hydrochloric Acid, Ammonia, and Dimethylamine

One of the main sources of uncertainty for understanding global warming is understanding the formation of larger secondary aerosols. The beginning stages start with the formation of prenucleation complexes from precursor monomers of acids, bases, and organic molecules. The detailed interactions responsible for prenucleation and subsequent aerosol formation are difficult to decipher experimentally. We present a computational chemistry study of the interactions between three different acid molecules and two different bases. By combining a comprehensive search routine covering many thousands of configurations at the semiempirical level with high level quantum chemical calculations of approximately 1000 clusters for every possible combination of clusters containing a sulfuric acid molecule, a formic acid molecule, a hydrochloric acid molecule, an ammonia molecule, a dimethylamine molecule, and 0–3 water molecules, we have completed an exhaustive search of the DLPNO-CCSD(T)/CBS//ωB97X-D/6-31++G** Gibbs free energy surface for this system. This first detailed study of HCl interacting with two other acids and two bases reveals the subtleties that exist in the formation of prenucleation complexes for this system. We find that nitric acid forms stronger interactions in dry clusters than hydrochloric acid does. Often as the clusters grow larger with hydration, the sequential energies of clusters containing hydrochloric acid become more favorable than those with nitric acid. The detailed geometries of each minimum free energy cluster are often more important than traditional acid or base strength, which makes a priori prediction of which atmospheric species will be most important for driving prenucleation growth quite difficult. The results presented in this paper add to the conclusions that hydrogen bond topology and the detailed structural interactions that are subtle interplays between enthalpy and entropy are as important as conventional ideas such as acid/base strength