title: The telegraph equation for cosmic-ray transport with weak adiabatic focusing

authors: Litvinenko, Yuri E.

subjects: particle emission

abstract: Time-dependent solutions of a spatial diffusion equation are often used to describe the transport of solar energetic particles, accelerated in large solar flares. Approximate analytical solutions of the diffusion approximation can complement and guide detailed numerical solutions of the Fokker-Planck equation for the particle distribution function. The accuracy of the diffusion approximation is limited, however, because the signal propagation speed is infinite in the diffusion limit. An improved description of cosmic-ray transport is provided by the telegraph equation, characterised by a finite signal propagation speed. We derive the telegraph equation for the particle density, taking into account adiabatic focusing in a large-scale interplanetary magnetic field in a weak focusing limit. As an illustration, we calculate a propagating pulse solution of the telegraph equation, determine the rise time when the maximum particle intensity is reached at a given distance from the Sun, and compare the results with those obtained in the diffusion approximation. In comparison with the diffusion equation, the telegraph equation predicts an asymmetrical shape of the pulse and a shorter rise time. These potentially significant differences suggest that the more accurate telegraph equation should be used in analysis of the solar energetic particle data, at least to quantify the accuracy of the focused diffusion model.

text: The telegraph equation for cosmic-ray transport with weak adiabatic focusing Time-dependent solutions of a spatial diffusion equation are often used to describe the transport of solar energetic particles, accelerated in large solar flares. Approximate analytical solutions of the diffusion approximation can complement and guide detailed numerical solutions of the Fokker-Planck equation for the particle distribution function. The accuracy of the diffusion approximation is limited, however, because the signal propagation speed is infinite in the diffusion limit. An improved description of cosmic-ray transport is provided by the telegraph equation, characterised by a finite signal propagation speed. We derive the telegraph equation for the particle density, taking into account adiabatic focusing in a large-scale interplanetary magnetic field in a weak focusing limit. As an illustration, we calculate a propagating pulse solution of the telegraph equation, determine the rise time when the maximum particle intensity is reached at a given distance from the Sun, and compare the results with those obtained in the diffusion approximation. In comparison with the diffusion equation, the telegraph equation predicts an asymmetrical shape of the pulse and a shorter rise time. These potentially significant differences suggest that the more accurate telegraph equation should be used in analysis of the solar energetic particle data, at least to quantify the accuracy of the focused diffusion model.

year: 2013

title: A hydrological drought index for the Clutha catchment, New Zealand

authors: Taylor, Malcolm

subjects: Clutha

abstract: The Clutha River is New Zealand’s largest river, both in terms of discharge and catchment size. It has a large seasonal flow variability with large spring and summer flows and very low flows in winter. The river is important for its contribution to energy production from two large hydro dams, irrigation for agriculture and horticulture, and tourist activities. The Clutha River flows are modified by discretionary releases of water from the only storage lake in the catchment, at Hawea. The mountainous South Island topography to the west means that a large part of the catchment is in a rain shadow and is regularly subject to long periods without any significant precipitation, similar to many other rain shadow catchments globally.

text: A hydrological drought index for the Clutha catchment, New Zealand The Clutha River is New Zealand’s largest river, both in terms of discharge and catchment size. It has a large seasonal flow variability with large spring and summer flows and very low flows in winter. The river is important for its contribution to energy production from two large hydro dams, irrigation for agriculture and horticulture, and tourist activities. The Clutha River flows are modified by discretionary releases of water from the only storage lake in the catchment, at Hawea. The mountainous South Island topography to the west means that a large part of the catchment is in a rain shadow and is regularly subject to long periods without any significant precipitation, similar to many other rain shadow catchments globally.

year: 2019

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