Effect of molecular relaxation on the propagation of sonic booms through a stratified atmosphere

Nonlinear acoustic wave propagation through a stratified atmosphere is considered. The initial signal is taken to be an isolated N-wave, which is the disturbance that is generated some distance away from a supersonic body in horizontal flight. The effect of cylindrical spreading and exponential density stratification on the propagation of the disturbance is considered, with the shock structure controlled by molecular relaxation mechanisms and by thermoviscous diffusion. An augmented Burgers equation is obtained and asymptotic solutions are derived based on the limit of small dissipation and dispersion. For a single relaxation mode, the solution depends on whether relaxation alone can support the shock or whether a sub-shock arises controlled by other mechanisms. The resulting shock structures are known as fully dispersed and partly dispersed shocks, respectively. In this paper, the spatial location of the transition between fully dispersed and partly dispersed shocks is identified for shocks propagating above and below the horizontal. This phenomenon is important in understanding the character of sonic booms since the transition to a partly dispersed shock structure leads to the appearance of a shorter scale in the shock rise-time, associated with the embedded sub-shock

Teaching mathematics at a distance: Trialling a wiki community to focus reflection and share resources

Professional development for academic staff in Higher Education is always more interesting and inspiring if good practice can be embedded in a way which is meaningful and relevant to the individual. The current project focuses on raising awareness of significant or difficult parts of a course, and promoting the exchange of good practice using a wiki environment. Our findings suggest that this methodology has promise, and is particularly valuable to new tutors, or at the start of a new course. The wiki can be used to host a repository of teaching materials and we illustrate a number of examples. We have also learnt a number of useful lessons on the ways in which a wiki might be used to support a staff community in the future, and offer a list of recommendations

Wave motion and vibration induced by turbulent flow

Imperial Users onl

The diffusion of satellite radio: A study of earlier adopters and non-adopters

This study examined the current and potential audience of satellite radio by using Roger\u27s diffusion of innovations theory as a theoretical framework (Rogers, 1962, 1971, 1983, 1995, 2003). Survey research was conducted in June of 2006 to discover adopters\u27 and non-adopters\u27 perceptions of satellite radio and competing technologies, their socioeconomic characteristics, demographics, and mass media use; Results of the survey indicated that the average earlier adopters of satellite radio are nearly 32 years of age, earned an average gross annual income of {dollar}40,000 to {dollar}50,000, and had more formal education than non-subscribers. The average non-adopter of satellite radio was nearly 26 years of age, averaged {dollar}20,000 to {dollar}30,000 gross annual income, and had some college education. Additionally, satellite radio subscribers more often than non-subscribers owned video game systems, video cameras, and TiVo

Investigations in the endocrinology of reproduction

The research papers submitted were published between 1964 and 1980 on the subjects of luteinizing hormone-releasing hormone (LH-RH), the hypothalamo-pituitary-ovarian system and artificial control of reproduction in domestic animals, methods of hormone assay and miscellaneous topics. Work was carried out in the Department of Physiology and Environmental Studies,University of Nottingham, in the Department of Physiology,University of Texas Southwestern Medical School at Dallas, Texas, U.S.A. and in the Laboratoire de Physiologie de la Lactation,Institut National de la Recherche Agronomique, Jouy-en-Josas, France.Chapter 1 contains publications on LH-RH and certain peptides related to LH-RH. These investigations were begun in Dallas in 1966 and have been continued to the present day at Nottingham. Included are papers on the localization of LH-RH within the hypothalamus and the synthesis, biological activity, plasma elimination and tissue degradation of LH-RH and fragments and analogues of the LH-RH molecule.Chapter 2 describes studies on the hypothalamo-pituitary- ovarian systems of female domestic animals. This research was carried out at Nottingham and included is work on the control of the lactational anoestrus of the sow and of gonadotrophin secretion and ovulation in the ewe.Chapter 3 consists of publications on the artificial control of reproduction in domestic animals. Studies on the sow arose from the work on lactational anoestrus described in Chapter 2.In the ewe, the possibility of using synthetic LH-RH for the induction of ovulation during seasonal anoestrus was investigated. The final paper in this chapter is a review of the endocrinology of meat production written at Jouy-en-Josas in 1979.Chapter 4 includes papers on the development and use of methods of hormone assay; pituitary tissue incubation for the assessment of LH-RH and both biological and radioimmunological methods for the gonadotrophins. These techniques have been the basis of much of the work described in other Chapters.Chapter 5 consists of several papers on aspects of endocrinology out of the main streams of the candidate's research

Discovering design: enhancing the capability to design at the cultural interface between first Australian and western design paradigms

This thesis claims that the First Australian design paradigm is distinct from the paradigms of design articulated in the Western canon (such as the rational and reflective design paradigms). I also investigate what it means to design at the cultural interface between First Australian and Western design paradigms, and identify the capability dimensions that are valued when expanding the freedom to design, from within a First Australia design paradigm as well as at the cultural interface. The methodology is informed by approaches to decolonising research at the cultural interface, which respect Indigenous ways of knowing, doing and being. My approach to the methodology informs the phenomenological basis of this study; I use Ricoeur’s approach to hermeneutical phenomenology (HP), as it appears to be suited to cross-cultural interpretation and compatible with the principles of Indigenous standpoint theory that guide research at the cultural interface. The results reveal that First Australian design should be understood as a process of experiential, reflective, respectful, relational discovery, rather than creation. It emphasises the relational aspect and should be understood as a process of connecting people with each other, and to the wider social and natural systems, to maintain a sense of harmony. When designing at the cultural interface between First and Later Australians, the most important differences and tensions seem to occur in the axiological and epistemological dimensions: the principles, the normative questions of what should be designed associated with innovation and creativity, the knowledge system characteristics, and issues of cultural identity and community. Valued capabilities when expanding the freedom to design at the cultural interface include the capability to develop empowering partnerships, and to maintain the integrity of cultural reproduction at the cultural interface

p53 directly regulates the glycosidase FUCA1 to promote chemotherapy-induced cell death

p53 is a central factor in tumor suppression as exemplified by its frequent loss in human cancer. p53 exerts its tumor suppressive effects in multiple ways, but the ability to invoke the eradication of damaged cells by programmed cell death is considered a key factor. The ways in which p53 promotes cell death can involve direct activation or engagement of the cell death machinery, or can be via indirect mechanisms, for example though regulation of ER stress and autophagy. We present here another level of control in p53-mediated tumor suppression by showing that p53 activates the glycosidase, FUCA1, a modulator of N-linked glycosylation. We show that p53 transcriptionally activates FUCA1 and that p53 modulates fucosidase activity via FUCA1 up-regulation. Importantly, we also report that chemotherapeutic drugs induce FUCA1 and fucosidase activity in a p53-dependent manner. In this context, while we found that over-expression of FUCA1 does not induce cell death, RNAi-mediated knockdown of endogenous FUCA1 significantly attenuates p53-dependent, chemotherapy-induced apoptotic death. In summary, these findings add an additional component to p53s tumor suppressive response and highlight another mechanism by which the tumor suppressor controls programmed cell death that could potentially be exploited for cancer therapy