title: The influence of porosity on the thermal diffusivity of foods

authors: Carson, James K.

subjects: Thermal diffusivity

abstract: Thermal diffusivity is an important parameter in unsteady-state heat transfer processes. Compared to other physical properties, there appears to be very few predictive models for thermal diffusivity in the literature. Most experimental studies have focussed on the influence of moisture content and temperature on thermal diffusivity and there is very little about the influence of porosity. In this study, the effects of porosity on thermal diffusivity are examined for selected foods and thermal diffusivity models from the literature are compared against measured data. The thermal diffusivity model proposed by Choi and Okos based on a weighted arithmetic mean of the components’ thermal diffusivities is not suitable for porous foods, resulting in large prediction errors. Applying a similar approach based on the harmonic mean rather than the arithmetic mean provided closer estimates of thermal diffusivity for both types of porous foods considered, but still produced unacceptable prediction errors (e.g. greater than 100 % when applied to model the thermal diffusivity of rice). Thermal diffusivity predicted from effective thermal conductivity, effective density and effective specific heat capacity data also resulted in unacceptable error. It is clear that there is scope for more work to be done in this area.

text: The influence of porosity on the thermal diffusivity of foods Thermal diffusivity is an important parameter in unsteady-state heat transfer processes. Compared to other physical properties, there appears to be very few predictive models for thermal diffusivity in the literature. Most experimental studies have focussed on the influence of moisture content and temperature on thermal diffusivity and there is very little about the influence of porosity. In this study, the effects of porosity on thermal diffusivity are examined for selected foods and thermal diffusivity models from the literature are compared against measured data. The thermal diffusivity model proposed by Choi and Okos based on a weighted arithmetic mean of the components’ thermal diffusivities is not suitable for porous foods, resulting in large prediction errors. Applying a similar approach based on the harmonic mean rather than the arithmetic mean provided closer estimates of thermal diffusivity for both types of porous foods considered, but still produced unacceptable prediction errors (e.g. greater than 100 % when applied to model the thermal diffusivity of rice). Thermal diffusivity predicted from effective thermal conductivity, effective density and effective specific heat capacity data also resulted in unacceptable error. It is clear that there is scope for more work to be done in this area.

year: 2018

title: The coherence of traumatic and non-traumatic memories: A tale of equivalence

authors: Taylor, Andrea

subjects: Memory

abstract: There is contention in the scientific literature about the mechanisms by which our memories for traumatic events operate. In one view, the extremely negative nature of traumatic events results in incomplete encoding, leaving memories for these events incoherent. In this view, incoherence promotes distress and therefore must be targeted over the course of treatment to enable recovery. In another view, traumatic memories operate using the same basic set of mechanisms as memories for non-traumatic events; traumatic memories are not uniquely incoherent, and evidence does not support the idea that treatment boosts coherence in a way that supports recovery. But across the literature, several counter-explanations hinder our interpretation of the existing findings. Over five experiments, we addressed these counter-explanations. We found little evidence to suggest people’s memories for traumatic events were incoherent, both in absolute terms and in relation to memories for non-traumatic events. Across our experiments, coherence did not vary in a systematic way depending on whether a memory was traumatic or non- traumatic. Moreover, we found evidence to suggest the way people recalled a memory affected their sense of how coherent that memory was. We also found that repeatedly recalling a memory, as happens in some therapies for posttraumatic stress disorder (PTSD), did not boost coherence. Instead, the data suggest repeated recall prevented a sense of lost coherence seen in memories not repeatedly recalled. Furthermore, we consistently found that memory coherence was not related to the degree of posttraumatic stress a person reported about that event. Mini meta-analyses on the data gathered across these five experiments, and their associated pilot studies, converged on the conclusions that a) traumatic memories are just as coherent as their non-traumatic counterparts, and b) there is no relation between coherence and symptomatology. Considered together, these findings are consistent with a basic mechanisms account of traumatic memories, and have implications for our conceptualisation of PTSD and the therapies designed to treat it.

text: The coherence of traumatic and non-traumatic memories: A tale of equivalence There is contention in the scientific literature about the mechanisms by which our memories for traumatic events operate. In one view, the extremely negative nature of traumatic events results in incomplete encoding, leaving memories for these events incoherent. In this view, incoherence promotes distress and therefore must be targeted over the course of treatment to enable recovery. In another view, traumatic memories operate using the same basic set of mechanisms as memories for non-traumatic events; traumatic memories are not uniquely incoherent, and evidence does not support the idea that treatment boosts coherence in a way that supports recovery. But across the literature, several counter-explanations hinder our interpretation of the existing findings. Over five experiments, we addressed these counter-explanations. We found little evidence to suggest people’s memories for traumatic events were incoherent, both in absolute terms and in relation to memories for non-traumatic events. Across our experiments, coherence did not vary in a systematic way depending on whether a memory was traumatic or non- traumatic. Moreover, we found evidence to suggest the way people recalled a memory affected their sense of how coherent that memory was. We also found that repeatedly recalling a memory, as happens in some therapies for posttraumatic stress disorder (PTSD), did not boost coherence. Instead, the data suggest repeated recall prevented a sense of lost coherence seen in memories not repeatedly recalled. Furthermore, we consistently found that memory coherence was not related to the degree of posttraumatic stress a person reported about that event. Mini meta-analyses on the data gathered across these five experiments, and their associated pilot studies, converged on the conclusions that a) traumatic memories are just as coherent as their non-traumatic counterparts, and b) there is no relation between coherence and symptomatology. Considered together, these findings are consistent with a basic mechanisms account of traumatic memories, and have implications for our conceptualisation of PTSD and the therapies designed to treat it.

year: 2023

title: Interpreting & practicing kaupapa Māori research in a community setting: The in’s and out’s

authors: Thompson, Keri

subjects: Māori

abstract: Pou Tuia Rangahau is a unique community based research unit based within a kaupapa Māori organisation. Kaupapa Māori methodologies are utilised, with the importance of these methodologies being that Māori are defining the process, doing the research for and about Māori, with the eventual outcome being meaningful to Māori. This paper is placed within this wider context of Kaupapa Māori and how it applies to the practice of research in particular. We discuss how we interpret and practice Kaupapa Māori Research (KMR) within an urban community based organisation by highlighting a particular piece of research that was undertaken by Pou Tuia Rangahau, the Research Unit of Te Runanga O Kirikiriroa Trust Inc.

text: Interpreting & practicing kaupapa Māori research in a community setting: The in’s and out’s Pou Tuia Rangahau is a unique community based research unit based within a kaupapa Māori organisation. Kaupapa Māori methodologies are utilised, with the importance of these methodologies being that Māori are defining the process, doing the research for and about Māori, with the eventual outcome being meaningful to Māori. This paper is placed within this wider context of Kaupapa Māori and how it applies to the practice of research in particular. We discuss how we interpret and practice Kaupapa Māori Research (KMR) within an urban community based organisation by highlighting a particular piece of research that was undertaken by Pou Tuia Rangahau, the Research Unit of Te Runanga O Kirikiriroa Trust Inc.

year: 2008