Mapping the Sensitive Volume of an Ion-Counting Nanodosimeter

We present two methods of independently mapping the dimensions of the sensitive volume in an ion-counting nanodosimeter. The first method is based on a calculational approach simulating the extraction of ions from the sensitive volume, and the second method on probing the sensitive volume with 250 MeV protons. Sensitive-volume maps obtained with both methods are compared and systematic errors inherent in both methods are quantified.Comment: 27 pages, 8 figures. Submitted to JINST, Jan. 16 200

Ring laser angle encoder

Ring laser angle encoder with a scanning photometer autocollimator and an isolation axis, provides continuous digital readout. It measures the angular difference in inertial attitudes of target /any phenomena generating or reflecting a light beam/ two at a time relative to target one at a time

Physics of multi-GEM structures

We show that physics of multi-GEM structures is rather complex, regarding the number of phenomena affecting detector performance. The high-pressure operation in noble gases and the ion feedback are considered in more detail. It is proposed that the dominant avalanche mechanism in He and Ne, at high pressures, is the associative ionization. Ion feedback effects related to the dependence on gas, pressure and gain and to possible avalanche extension outside the GEM holes are discussed.Comment: Presented at the 8th International Conference on Instrumentation for Colliding Beam Physics, Novosibirsk, Febuary 28 - March 6, 2002. To be published in Nucl. Instr. and Meth.

Acoustophoresis in Variously Shaped Liquid Droplets

The ability to precisely trap, transport and manipulate micrometer-sized objects, including biological cells, DNA-coated microspheres and microorganisms, is very important in life science studies and biomedical applications. In this study, acoustic radiation force in an ultrasonic standing wave field is used for micro-objects manipulation, a technique termed as acoustophoresis. Free surfaces of liquid droplets are used as sound reflectors to confine sound waves inside the droplets. Two techniques were developed for precise control of droplet shapes: edge pinning and hydrophilic/hydrophobic interface pinning. For all tested droplet shapes, including circular, annular and rectangular, our experiments show that polymer micro particles can be manipulated by ultrasound and form into a variety of patterns, for example, concentric rings and radial lines in an annular droplet. The complexity of the pattern increases with increasing frequency, and the observations are in line with simulation results. The acoustic manipulation technique developed here has the potential to be integrated into a more complex on-chip microfluidic circuit. Especially because our method is well compatible with electrowetting technology, which is a powerful tool for manipulating droplets with free surfaces, the combination of the two methods can provide more versatile manipulation abilities and may bring a wealth of novel applications. In the end, we demonstrate for the first time that acoustophoresis can be used for manipulating Caenorhabditis elegans

Ethics and Business

To many, the old adage that business and ethics never mix, has been reinforced by the constant revelations of the various tribunals set up since the early 1990’s. Laura Nash, Associate Professor at Boston University Graduate School of Management has stated “Many an executive today voices cynicism at the relevance of moral inquiry to managerial practice. For many reasons from the external fact of greed to the very different ways in which we tend to think about managing and morality, ethics and business have often seemed if not downright contradictory, at least several worlds apart” Commentators on Irish business practice might tend to agree with Nash as Irish company law has been characterised, by a culture of non compliance with only 13% of companies filing returns on time in 1997 to the Companies Office. Persistent breaches of the Companies Act, banking scandals, alleged payments to politicians, and company non compliance with many regulatory bodies, would lead most observers to believe that the question of business ethics has never been high on the agenda of certain Irish companies and entrepreneurs

Interactionist Qualitative Research as a Semiotic Mediation Activity

In this article, we introduce qualitative research from an interactionist perspective. We specifically explore qualitative research itself as a semiotic process with associated actions. This enables researchers to make sense of human interactions in the world rather than solely focusing on semiotic analysis of qualitative data. We introduce Peirce’s semiotics and Vygotsky’s mediated action as tools for conceptualizing qualitative research in a semiotic mediation process. Understanding qualitative research as a semiotic mediation can help social scientists better understand their own role in research, while vicariously gaining experiences about human interactions that they later present to others