title: Technique to assess the compatibility of medical implants to the RF Field in MRI

authors: McCabe, Steven Owen

subjects: Magnetic resonance imaging

abstract: The standard technique for determining the compatibility of medical implants to the magnetic and RF fields present in Magnetic Resonance Imaging (MRI), requires access to an MRI machine. For implants comprising metals of mostly the non-ferrous kind, it is only the RF field of an MRI machine that is of concern. Implant electrodes can concentrate the RF field in the surrounding tissue and give rise to joule heating. The inherent design of Spinal Cord Stimulators (SCS) and Deep Brain Stimulators (DBS) makes these implants particularly susceptible to hazardous levels of RF heating. We propose a technique that offers a quick and indicative assessment of the compatibility of implant leads to the RF field in 3-Tesla MRI, without needing access to an MRI machine. A dipole antenna, driven by a power amplifier and Continuous Wave (CW), injects RF energy into a gelled saline phantom. The heating in the gel near a test implant electrode is monitored with a fiber optic thermometer. The results are calibrated against measurements made in a 3-Tesla MRI machine.

text: Technique to assess the compatibility of medical implants to the RF Field in MRI The standard technique for determining the compatibility of medical implants to the magnetic and RF fields present in Magnetic Resonance Imaging (MRI), requires access to an MRI machine. For implants comprising metals of mostly the non-ferrous kind, it is only the RF field of an MRI machine that is of concern. Implant electrodes can concentrate the RF field in the surrounding tissue and give rise to joule heating. The inherent design of Spinal Cord Stimulators (SCS) and Deep Brain Stimulators (DBS) makes these implants particularly susceptible to hazardous levels of RF heating. We propose a technique that offers a quick and indicative assessment of the compatibility of implant leads to the RF field in 3-Tesla MRI, without needing access to an MRI machine. A dipole antenna, driven by a power amplifier and Continuous Wave (CW), injects RF energy into a gelled saline phantom. The heating in the gel near a test implant electrode is monitored with a fiber optic thermometer. The results are calibrated against measurements made in a 3-Tesla MRI machine.

year: 2015

title: Selecting one from many: The development of a scalable visualization tool

authors: Apperley, Mark

subjects: Science & Technology

abstract: This paper describes visualisation tools to support the task of selecting one object from a collection of many on the basis of its attribute values. For this frequently encountered task we identify a set of tools appropriate to a spectrum of collection sizes extending from hundreds of thousands to as few as ten or twenty. Although some of the tools have not previously been reported, and some have received only cursory attention in the literature, others are well known. This paper presents the tools in a coherent and consistent manner, showing relationships and progressions between them, identifying their principal attributes and relating them to the problem solver's cognitive task. We conclude with a proposal for integrating techniques within a single tool in order to deal with a continuum of working set sizes.

text: Selecting one from many: The development of a scalable visualization tool This paper describes visualisation tools to support the task of selecting one object from a collection of many on the basis of its attribute values. For this frequently encountered task we identify a set of tools appropriate to a spectrum of collection sizes extending from hundreds of thousands to as few as ten or twenty. Although some of the tools have not previously been reported, and some have received only cursory attention in the literature, others are well known. This paper presents the tools in a coherent and consistent manner, showing relationships and progressions between them, identifying their principal attributes and relating them to the problem solver's cognitive task. We conclude with a proposal for integrating techniques within a single tool in order to deal with a continuum of working set sizes.

year: 2001

title: The use of Māori words in National Science Challenge online discourse

authors: Calude, Andreea S.

subjects: Maori loanwords

abstract: New Zealand English is well-known for its heavy borrowing of words from Māori. This lexical component, unique to New Zealand English alone has been studied intensely over the last 50 years, particularly in newspaper media. Current research suggests the use is still increasing today, primarily in Māori-related contexts. Here, we analyse a surprising and unexpected use of Māori loanwords in science digital discourse (neither genre being previously investigated), where we discover a strong presence of Māori borrowings in National Science Challenge website and Twitter content. Using corpus linguistics methods, we argue that the use of Māori loanwords in this genre functions as a national identity building tool, used by various authors to signal that the ‘challenges’ the country faces are uniquely New Zealand’s ‘challenges’.

text: The use of Māori words in National Science Challenge online discourse New Zealand English is well-known for its heavy borrowing of words from Māori. This lexical component, unique to New Zealand English alone has been studied intensely over the last 50 years, particularly in newspaper media. Current research suggests the use is still increasing today, primarily in Māori-related contexts. Here, we analyse a surprising and unexpected use of Māori loanwords in science digital discourse (neither genre being previously investigated), where we discover a strong presence of Māori borrowings in National Science Challenge website and Twitter content. Using corpus linguistics methods, we argue that the use of Māori loanwords in this genre functions as a national identity building tool, used by various authors to signal that the ‘challenges’ the country faces are uniquely New Zealand’s ‘challenges’.

year: 2019