title: A comparison of demand for two different feeds with horses (Equus callabus)

authors: Armistead, Mary Jennie

subjects: operant

abstract: There are few studies with horses that examine either their food preferences or the use of increasing work requirements to assess their demand for food. The first experiment used Multiple-Stimulus-Without-Replacement procedure to measure six horses' preferences for four different feeds. From these, a high- (Yearling mix) and a low- (Rice) preference feed were selected. The horses were then exposed to two series of increasing fixed ratio (FR) schedules with each of two feeds, in fixed-length sessions. The overall response rates were bitonic, running response rates decreased and average post-reinforcement pauses increased with increases in fixed-ratio value, typical of previous research. Yearling mix maintained faster responding to higher fixed-ratio values for most horses than did Rice. The demand functions (i.e., the numbers of reinforcers obtained in a session as functions of the ratio size on double logarithmic coordinates) showed mixed elasticity for both Yearling mix and Rice (where there were enough data that a function could be sensibly fitted). There were lower levels of demand (i.e., number of reinforcers obtained) for Rice than Yearling mix at small fixed ratio values, the reverse of the findings reported previously for reinforcer size and preference value. It is suggested that this difference could have been the result of the open economic conditions of this study. However, the equation suggested by Hursh and Silberberg (2008) provided a good description of the data in this study, with Rice having a lower essential value that Yearling mix.

text: A comparison of demand for two different feeds with horses (Equus callabus) There are few studies with horses that examine either their food preferences or the use of increasing work requirements to assess their demand for food. The first experiment used Multiple-Stimulus-Without-Replacement procedure to measure six horses' preferences for four different feeds. From these, a high- (Yearling mix) and a low- (Rice) preference feed were selected. The horses were then exposed to two series of increasing fixed ratio (FR) schedules with each of two feeds, in fixed-length sessions. The overall response rates were bitonic, running response rates decreased and average post-reinforcement pauses increased with increases in fixed-ratio value, typical of previous research. Yearling mix maintained faster responding to higher fixed-ratio values for most horses than did Rice. The demand functions (i.e., the numbers of reinforcers obtained in a session as functions of the ratio size on double logarithmic coordinates) showed mixed elasticity for both Yearling mix and Rice (where there were enough data that a function could be sensibly fitted). There were lower levels of demand (i.e., number of reinforcers obtained) for Rice than Yearling mix at small fixed ratio values, the reverse of the findings reported previously for reinforcer size and preference value. It is suggested that this difference could have been the result of the open economic conditions of this study. However, the equation suggested by Hursh and Silberberg (2008) provided a good description of the data in this study, with Rice having a lower essential value that Yearling mix.

year: 2009

title: The kinetics of the dissociation of dihydroxyacetone dimer in aprotic media

authors: Owens, Adrian

subjects: Dihydroxyacetone

abstract: The dissociation of the dihydroxyacetone (DHA) dimer in mānuka honey has previously been proposed to be the rate determining step in the overall conversion of DHA to methylglyoxal, the agent reported to be responsible for the non-peroxide anti-bacterial activity displayed by mānuka honey.

The ¹H and ¹³C NMR spectra for the DHA dimer and the DHA monomer in DMSO-d6 were assigned using 1D and 2D NMR spectroscopy.

¹H and ¹³C NMR spectroscopy were utilised to investigate the kinetics of the dissociation of the DHA dimer in DMSO-d6, an anhydrous solvent chosen to mimic the dehydrating conditions present in the honey matrix.

Four series of kinetic experiments were conducted, one without catalysis, one with D₂O catalysis, one with CD₃COOD catalysis and one with CD₃COOD/CD₃COOD catalysis. Each of these experiments obtained the equilibrium constant, K and the rate constants k, k₁ and k₋₁ for the dissociation of the DHA dimer under different conditions that may be present in the honey matrix, with the exclusion of the CD₃COOD/CD₃COOD catalysed experiments which were conducted as part of the investigation to determine a proposed reaction mechanism.

Two reaction intermediates were observed in the CD₃COOD catalysed experiments, they were characterised and provided supporting evidence for a proposed acid-catalysed reaction mechanism for the DHA dimer dissociation. The absence of reaction intermediates in the D₂O catalysed experiments provided supporting evidence for a proposed base-catalysed reaction mechanism for the DHA dimer dissociation.

Reaction mechanisms for the DHA dimer dissociation in DMSO-d6 and mānuka honey were proposed based on the findings of previous studies and the findings associated with the kinetic experiments conducted in this study.

text: The kinetics of the dissociation of dihydroxyacetone dimer in aprotic media The dissociation of the dihydroxyacetone (DHA) dimer in mānuka honey has previously been proposed to be the rate determining step in the overall conversion of DHA to methylglyoxal, the agent reported to be responsible for the non-peroxide anti-bacterial activity displayed by mānuka honey.

The ¹H and ¹³C NMR spectra for the DHA dimer and the DHA monomer in DMSO-d6 were assigned using 1D and 2D NMR spectroscopy.

¹H and ¹³C NMR spectroscopy were utilised to investigate the kinetics of the dissociation of the DHA dimer in DMSO-d6, an anhydrous solvent chosen to mimic the dehydrating conditions present in the honey matrix.

Four series of kinetic experiments were conducted, one without catalysis, one with D₂O catalysis, one with CD₃COOD catalysis and one with CD₃COOD/CD₃COOD catalysis. Each of these experiments obtained the equilibrium constant, K and the rate constants k, k₁ and k₋₁ for the dissociation of the DHA dimer under different conditions that may be present in the honey matrix, with the exclusion of the CD₃COOD/CD₃COOD catalysed experiments which were conducted as part of the investigation to determine a proposed reaction mechanism.

Two reaction intermediates were observed in the CD₃COOD catalysed experiments, they were characterised and provided supporting evidence for a proposed acid-catalysed reaction mechanism for the DHA dimer dissociation. The absence of reaction intermediates in the D₂O catalysed experiments provided supporting evidence for a proposed base-catalysed reaction mechanism for the DHA dimer dissociation.

Reaction mechanisms for the DHA dimer dissociation in DMSO-d6 and mānuka honey were proposed based on the findings of previous studies and the findings associated with the kinetic experiments conducted in this study.

year: 2016

title: Understanding the context of hospital transfers and away-from-home hospitalisations for Māori

authors: Cormack, Donna

subjects: Humans

abstract: In Aotearoa New Zealand, people regularly travel away from their home to receive hospital care. While the role of whānau support for patients in hospital is critical for Māori, there is little information about away-from-home hospitalisations. This paper describes the frequency and patterning of away-from-home hospitalisations and inter-hospital transfers for Māori. Data from the National Minimum Dataset (NMDS), for the 6-year period of 1 January 2009-31 December 2014, were analysed. Basic frequencies, means and descriptive statistics were produced using SAS software. We found that more than 10% of all routine hospitalisations constituted an away-from-home hospitalisation for Māori; that is, a hospitalisation that was in a district health board (DHB) other than the DHB of usual residence for the patient. One quarter (25.19%) of transfer hospitalisations were to a DHB other than the patient's DHB of domicile. Away-from-home hospital admissions increase for Māori as deprivation increases for both routine and transfer admissions, with over half of Māori hospital admissions among people who live in areas of high deprivation. This analysis aids in understanding away-from-home hospitalisations for Māori whānau, the characteristics associated with these types of hospitalisations and supports the development and implementation of policies which better meet whānau Māori needs. The cumulative impact of the need to travel to hospital for care, levels of poverty and a primarily reimbursement-based travel assistance system all perpetuate an unequal cost burden placed upon Māori whānau.

text: Understanding the context of hospital transfers and away-from-home hospitalisations for Māori In Aotearoa New Zealand, people regularly travel away from their home to receive hospital care. While the role of whānau support for patients in hospital is critical for Māori, there is little information about away-from-home hospitalisations. This paper describes the frequency and patterning of away-from-home hospitalisations and inter-hospital transfers for Māori. Data from the National Minimum Dataset (NMDS), for the 6-year period of 1 January 2009-31 December 2014, were analysed. Basic frequencies, means and descriptive statistics were produced using SAS software. We found that more than 10% of all routine hospitalisations constituted an away-from-home hospitalisation for Māori; that is, a hospitalisation that was in a district health board (DHB) other than the DHB of usual residence for the patient. One quarter (25.19%) of transfer hospitalisations were to a DHB other than the patient's DHB of domicile. Away-from-home hospital admissions increase for Māori as deprivation increases for both routine and transfer admissions, with over half of Māori hospital admissions among people who live in areas of high deprivation. This analysis aids in understanding away-from-home hospitalisations for Māori whānau, the characteristics associated with these types of hospitalisations and supports the development and implementation of policies which better meet whānau Māori needs. The cumulative impact of the need to travel to hospital for care, levels of poverty and a primarily reimbursement-based travel assistance system all perpetuate an unequal cost burden placed upon Māori whānau.

year: 2022-11-11