title: Cause and Amelioration of MRI-Induced Heating Through Medical Implant Lead Wires

authors: McCabe, Steven Owen

abstract: The RF fields present in magnetic resonance imaging (MRI) scanners can induce hazardous heating in patients wearing medical implants. The inherent design and locale of deep brain stimulators (DBS) and spinal cord stimulators (SCS) make them particularly susceptible. We apply antenna concepts and use electromagnetic (EM) simulation to explain the phenomenon and anticipate its sensitivity to lead wire length. We anticipate that a DC resistance of less than 50 Ω/m and an RF impedance of more than 1:23kΩ/m would be required for a safe electrode for SCS use. We investigate the possibility of manipulating wire conductivity and diameter in order to use the skin depth effect to achieve a safe electrode. The effect of the thickness and permittivity of insulation surrounding the wires is explored.

text: Cause and Amelioration of MRI-Induced Heating Through Medical Implant Lead Wires The RF fields present in magnetic resonance imaging (MRI) scanners can induce hazardous heating in patients wearing medical implants. The inherent design and locale of deep brain stimulators (DBS) and spinal cord stimulators (SCS) make them particularly susceptible. We apply antenna concepts and use electromagnetic (EM) simulation to explain the phenomenon and anticipate its sensitivity to lead wire length. We anticipate that a DC resistance of less than 50 Ω/m and an RF impedance of more than 1:23kΩ/m would be required for a safe electrode for SCS use. We investigate the possibility of manipulating wire conductivity and diameter in order to use the skin depth effect to achieve a safe electrode. The effect of the thickness and permittivity of insulation surrounding the wires is explored.

year: 2014

title: Faunal extinction and human habitation in New Caledonia: Initial results and implications of new research at the Pindai Caves

authors: Anderson, Atholl

subjects: New Caledonia

abstract: Archaeological and palaeontological investigations occurred in 2003 at the Pindai Caves in New Caledonia, where remains of prehistoric settlement exist in conjunction with the richest fossil deposits found to date on Grand Terre. Among more than 45 bird taxa in our excavations at least 20 that are locally or globally extinct are represented at levels immediately below or within the era of human occupation. These include the giant megapode, Sylviornis sp., the flightless swamphen, Porphyrio kukuwiedei, and other rails, a kagu, pigeons, a large snipe, Coenocorypha sp., several taxa of owls, a nightjar, and an owlet-nightjar. Unresolved problems in dating and taphonomy, however, make it difficult to specify the strength of cultural associations and thus the extent to which human activities were responsible for extinctions or extirpations. We present the first radiocarbon dates upon Sylviornis bone, showing that, at least, the species survived into the late Holocene. Relatively frequent occurrence of Sylviornis bone in the cultural levels, coupled with a radiocarbon date on a bone sample of about 3000 calBP make a case for human contact.

text: Faunal extinction and human habitation in New Caledonia: Initial results and implications of new research at the Pindai Caves Archaeological and palaeontological investigations occurred in 2003 at the Pindai Caves in New Caledonia, where remains of prehistoric settlement exist in conjunction with the richest fossil deposits found to date on Grand Terre. Among more than 45 bird taxa in our excavations at least 20 that are locally or globally extinct are represented at levels immediately below or within the era of human occupation. These include the giant megapode, Sylviornis sp., the flightless swamphen, Porphyrio kukuwiedei, and other rails, a kagu, pigeons, a large snipe, Coenocorypha sp., several taxa of owls, a nightjar, and an owlet-nightjar. Unresolved problems in dating and taphonomy, however, make it difficult to specify the strength of cultural associations and thus the extent to which human activities were responsible for extinctions or extirpations. We present the first radiocarbon dates upon Sylviornis bone, showing that, at least, the species survived into the late Holocene. Relatively frequent occurrence of Sylviornis bone in the cultural levels, coupled with a radiocarbon date on a bone sample of about 3000 calBP make a case for human contact.

year: 2010

title: Observations by and conversations with health workers and hospital personnel involved in transferring Maori patients and whānau to Waikato Hospital in Aotearoa New Zealand

authors: Masters-Awatere, Bridgette

subjects: Science & Technology

abstract: The predominant focus of Aotearoa New Zealand’s public health system on biomedical models of health has left little room for meaningful engagement with holistic indigenous approaches. Culturally appropriate provision and support are recognized for their relevance and importance during hospital transferals. Hospital staff involved in transfers to one of New Zealand’s trauma centers share their observations of whānau Māori engagement during an admission away from their home base. Sixteen key informants share their experiences, which are presented as strategies and challenges to whānau engagement. Three main themes highlight challenges within the health system that make it difficult for hospital staff to engage whānau in the desired ways and as often as both parties would like. Key informants described services and practices that are not designed with patients and their whānau in mind; instead they are designed by clinicians around the needs of administrative systems. As employees within the public health system, key informants felt powerless to challenge dominant settings. Nevertheless, employees managed to circumnavigate processes. Our findings highlight the need for continued decolonization and anti-racism work within public health settings.

text: Observations by and conversations with health workers and hospital personnel involved in transferring Maori patients and whānau to Waikato Hospital in Aotearoa New Zealand The predominant focus of Aotearoa New Zealand’s public health system on biomedical models of health has left little room for meaningful engagement with holistic indigenous approaches. Culturally appropriate provision and support are recognized for their relevance and importance during hospital transferals. Hospital staff involved in transfers to one of New Zealand’s trauma centers share their observations of whānau Māori engagement during an admission away from their home base. Sixteen key informants share their experiences, which are presented as strategies and challenges to whānau engagement. Three main themes highlight challenges within the health system that make it difficult for hospital staff to engage whānau in the desired ways and as often as both parties would like. Key informants described services and practices that are not designed with patients and their whānau in mind; instead they are designed by clinicians around the needs of administrative systems. As employees within the public health system, key informants felt powerless to challenge dominant settings. Nevertheless, employees managed to circumnavigate processes. Our findings highlight the need for continued decolonization and anti-racism work within public health settings.

year: 2020