Valiente Kroon's obstructions to smoothness at infinity

We conjecture an interpretation in terms of multipole moments of the obstructions to smoothness at infinity found for time-symmetric, conformally-flat initial data by Valiente Kroon (Comm. Math. Phys. 244 (2004), 133-156).Comment: To appear in GR

Engineered surfaces to control secondary electron emission for multipactor suppression

A significant problem for space-based systems is multipactor - an avalanche of electrons caused by repeated secondary electron emission (SEE). The consequences of multipactor range from altering the operation of radio frequency (RF) devices to permanent device damage. Existing efforts to suppress multipactor rely heavily on limiting power levels below a multipactor threshold [1]. This research applies surface micromachining techniques to create porous surfaces to control the secondary electron yield (SEY) of a material for multipactor suppression. Surface characteristics of interest include pore aspect ratio and density. A discussion is provided on the advantage of using electroplating (vice etching) to create porous surfaces for studying the relationships between SEY and pore aspect ratio & density (i.e. porosity). Preventing multipactor through SEY reduction will allow power level restrictions to be eased, leading to more powerful and capable space-based systems

Revisiting Duffus and Dearden's wildlife tourism framework

This paper revisits Duffus and Dearden (1990) article 'Non-Consumptive Wildlife-Oriented Recreation: a conceptual framework' published in Biological Conservation two decades ago. This model was developed as a tool to assist managers and researchers in achieving the best outcomes for both environmental conservation and the provision of wildlife tourism experiences. The body of literature examining wildlife tourism has grown significantly over the intervening period; however, this highly respected model has not been subject to critical review even though a number of recent empirical studies have successfully applied the concept. This has created an opportunity for reflection on its merits and potential. In particular, this paper discusses these findings to assess the contemporary value of this approach. It is contended that the framework still provides an appropriate means of predicting and managing change in a wildlife tourism system. Given the ability of the model to combine theoretical perspectives with practical outcomes and the now emerging body of literature based upon it, continued application and refinement of this model is more pertinent than ever

O Heart Of Mine

https://digitalcommons.library.umaine.edu/mmb-vp/5792/thumbnail.jp

Loss of Transcriptional Silencing Causes Sterility in Old Mother Cells of S. cerevisiae

AbstractWe show that sterility is an aging-specific phenotype in S. cerevisiae and, by genetic and physical means, demonstrate that this phenotype results from a loss of silencing in most old cells by the SIR complex at the HM loci. This loss of silencing is specific because transcription of genes, such as MEI4 and DCM1, normally induced by sporulation, is not observed, while transcription of HMRa is observed. These findings pinpoint the molecular cause of an aging-specific phenotype in yeast. Further, they provide direct evidence for a breakdown of silencing in old cells, as predicted from earlier findings that SIR4 is a determinant of life span in this organism