title: Photon migration in highly scattering media as a measurement technique on automated cow milking systems

authors: Khoo, Geoffrey

abstract: An investigation has been performed on the scattering properties of cow's milk. The main aim of the study has been to determine the usefulness of photon migration techniques in the measurement of milk components, and the extent to which they can be applied. Online applications are also investigated. The milk components that influence the optical scattering properties the most are the fat content and the protein content. Fat in milk exists in the form of small globules in a range of diameters from under 1 μrn to as large as 20 μrn. These globules are the major contributor to the light scattering properties of the milk. Milk protein is also a contributor to the scattering, but to a much lesser extent. Another component of milk that is of interest is the somatic cell concentration. These cells are usually present in milk at a low level, ranging from about 5 x 104 cells mL- 1up to 2 x 105 cells mL-1• Their numbers in milk dramatically increase with the onset of a mastitis infection. The somatic cell count is one of the primary measurements used in the dairy industry to monitor udder health and mastitis. Since milk is a highly scattering medium, one needs to choose a suitable mathematical model to characterise it so that quantitative measurements can be made. The diffusion approximation, a simplified version of transport theory, was selected. The derivation and the limitations of the diffusion approximation were discussed and noted in order to ensure that any subsequent measurements made with milk fell within the limits of the theory. A photon migration instrument (PMI) was built using the principles from the diffusion approximation theory. The instrument was configured to work with multiple-distance measurements. It was tested with a suspension of uniform microspheres and was shown to return results that agreed with Mie theory. Experiments were performed using the photon migration instrument with homogenised and raw milk. A good correlation was found between the fat content and the reduced-scattering coefficient. Homogenised milk samples of varying fat content were made by mixing trim milk with homogenised cream while raw milk of varying fat content was obtained from a robotic milking system. Both milks were tested with3the photon migration instrument - the homogenised milk was tested off-line, while the raw milk was tested with the instrument beside the robotic milking system. It was found that the instrument could determine the fat content in homogenised and raw milk with a precision of ±1.0 % and ±2.0 % milk fat content respectively. Protein and somatic cell count had a poor correlation with either the absorption coefficient or the reduced-scattering coefficient at a 670 nm wavelength. The precision of the raw milk fat content measurements can be increased by separating the milk samples by breed. Grouping milk samples from Friesian cows separately from milk samples from Jersey cows yielded precisions of± 1.6 % and ± 1.4% respectively. Further increases in precision could be obtained by separating out the results per cow, resulting in fat percentage measurements with a precision as high as±0.8 %. One of the more significant conclusions is that the fat globule particle size distribution is similar within the breed of cow and certainly similar from day-to-day with a single cow. Fluorescence photon diffusion techniques using the DNA stain ethidium bromide were used to determine somatic cell count. The results of this work showed that high cell-count samples could be quantified, with a lower detection limit of 4 x 105 cells mL- 1• The lower detection limit was too high, and during attempts to reduce it, evidence for an ethidium bromide inhibitor was found. This inhibitor appeared to use up free ethidium bromide without changing its fluorescence lifetime. This was shown by experiments where the milk was diluted with Intra Lipid to remove the contribution that differences in the absorption and reduced-scattering coefficient would make. The discovery of the ethidium bromide inhibitor was another significant conclusion of this work, but further investigation of the inhibitor was beyond the scope of this dissertation. The primary conclusion of this thesis is that photon migration techniques can measure some milk components online directly, notably fat content and somatic cell count. Improvements to the instrument are required however, in order to improve the precision of the measurements to the level required by the dairy industry.

text: Photon migration in highly scattering media as a measurement technique on automated cow milking systems An investigation has been performed on the scattering properties of cow's milk. The main aim of the study has been to determine the usefulness of photon migration techniques in the measurement of milk components, and the extent to which they can be applied. Online applications are also investigated. The milk components that influence the optical scattering properties the most are the fat content and the protein content. Fat in milk exists in the form of small globules in a range of diameters from under 1 μrn to as large as 20 μrn. These globules are the major contributor to the light scattering properties of the milk. Milk protein is also a contributor to the scattering, but to a much lesser extent. Another component of milk that is of interest is the somatic cell concentration. These cells are usually present in milk at a low level, ranging from about 5 x 104 cells mL- 1up to 2 x 105 cells mL-1• Their numbers in milk dramatically increase with the onset of a mastitis infection. The somatic cell count is one of the primary measurements used in the dairy industry to monitor udder health and mastitis. Since milk is a highly scattering medium, one needs to choose a suitable mathematical model to characterise it so that quantitative measurements can be made. The diffusion approximation, a simplified version of transport theory, was selected. The derivation and the limitations of the diffusion approximation were discussed and noted in order to ensure that any subsequent measurements made with milk fell within the limits of the theory. A photon migration instrument (PMI) was built using the principles from the diffusion approximation theory. The instrument was configured to work with multiple-distance measurements. It was tested with a suspension of uniform microspheres and was shown to return results that agreed with Mie theory. Experiments were performed using the photon migration instrument with homogenised and raw milk. A good correlation was found between the fat content and the reduced-scattering coefficient. Homogenised milk samples of varying fat content were made by mixing trim milk with homogenised cream while raw milk of varying fat content was obtained from a robotic milking system. Both milks were tested with3the photon migration instrument - the homogenised milk was tested off-line, while the raw milk was tested with the instrument beside the robotic milking system. It was found that the instrument could determine the fat content in homogenised and raw milk with a precision of ±1.0 % and ±2.0 % milk fat content respectively. Protein and somatic cell count had a poor correlation with either the absorption coefficient or the reduced-scattering coefficient at a 670 nm wavelength. The precision of the raw milk fat content measurements can be increased by separating the milk samples by breed. Grouping milk samples from Friesian cows separately from milk samples from Jersey cows yielded precisions of± 1.6 % and ± 1.4% respectively. Further increases in precision could be obtained by separating out the results per cow, resulting in fat percentage measurements with a precision as high as±0.8 %. One of the more significant conclusions is that the fat globule particle size distribution is similar within the breed of cow and certainly similar from day-to-day with a single cow. Fluorescence photon diffusion techniques using the DNA stain ethidium bromide were used to determine somatic cell count. The results of this work showed that high cell-count samples could be quantified, with a lower detection limit of 4 x 105 cells mL- 1• The lower detection limit was too high, and during attempts to reduce it, evidence for an ethidium bromide inhibitor was found. This inhibitor appeared to use up free ethidium bromide without changing its fluorescence lifetime. This was shown by experiments where the milk was diluted with Intra Lipid to remove the contribution that differences in the absorption and reduced-scattering coefficient would make. The discovery of the ethidium bromide inhibitor was another significant conclusion of this work, but further investigation of the inhibitor was beyond the scope of this dissertation. The primary conclusion of this thesis is that photon migration techniques can measure some milk components online directly, notably fat content and somatic cell count. Improvements to the instrument are required however, in order to improve the precision of the measurements to the level required by the dairy industry.

year: 2005

title: Tensile behaviour of radiata pine with different moisture contents at elevated temperatures

authors: Pearson, Hamish

subjects: Drying

abstract: The aim of this study was to obtain tensile elastic modulus (EM) information for radiata pine (Pinus radiata D. Don) sapwood in tangential grain direction, over a temperature range of 70 degrees C to 150 degrees C for a wide range of moisture contents. Such information is scarce, probably because of difficulties with research equipment design and process control strategies to perform accurate tests. As expected, EM dramatically decreased with increasing temperature and moisture content. The results were modelled to yield a relationship between stress and strain. The results were also successfully transposed into a mastercurve based on temperature-moisture equivalence through a modified form of the Williams, Landel, and Ferry equation for amorphous polymers. This result is consistent with the view that wood is visco-plastic around the glass transition zone of the ligno-hemicellulosic matrix. It is demonstrated that moisture and temperature can play a significant role in reducing stress during drying, regardless of the drying time. Properties of wood, such as tensile elastic information at elevated temperatures, are important for mechanical design, distortion modelling and understanding the fundamental behaviour of wood in general.

text: Tensile behaviour of radiata pine with different moisture contents at elevated temperatures The aim of this study was to obtain tensile elastic modulus (EM) information for radiata pine (Pinus radiata D. Don) sapwood in tangential grain direction, over a temperature range of 70 degrees C to 150 degrees C for a wide range of moisture contents. Such information is scarce, probably because of difficulties with research equipment design and process control strategies to perform accurate tests. As expected, EM dramatically decreased with increasing temperature and moisture content. The results were modelled to yield a relationship between stress and strain. The results were also successfully transposed into a mastercurve based on temperature-moisture equivalence through a modified form of the Williams, Landel, and Ferry equation for amorphous polymers. This result is consistent with the view that wood is visco-plastic around the glass transition zone of the ligno-hemicellulosic matrix. It is demonstrated that moisture and temperature can play a significant role in reducing stress during drying, regardless of the drying time. Properties of wood, such as tensile elastic information at elevated temperatures, are important for mechanical design, distortion modelling and understanding the fundamental behaviour of wood in general.

year: 2012

title: Does within-treatment change on dynamic risk factors and psychopathology predict recidivism for men graduating from Tai Aroha?

authors: Tanner Dempsey, Arden

subjects: dynamic risk factors

abstract: Dynamic risk factors are modifiable aspects of justice-involved people and their environment that can change over time and are associated with criminal behaviour. Because they are considered changeable, they are therefore typically the focus of rehabilitative treatment (Bonta & Andrews, 2024). Research shows that correctional rehabilitation that targets dynamic risk factors effectively reduces recidivism, and psychometric tools assessing these factors generally show improvements during treatment. However, there is a missing link; current research lacks consistent evidence linking changes on dynamic risk factors during treatment to recidivism. Relatedly, there are few studies assessing within-treatment changes in psychopathology and how they may affect recidivism, though they are commonly assessed alongside dynamic risk factors in correctional settings. 
This study, involving 164 people with violent offence convictions who completed the Tai Aroha community treatment programme, aimed to address this missing link. A battery of tests measured pre- and post-programme included dynamic risk factor measures, the Anger Disorders Scale (ADS), Psychological Inventory of Criminal Thinking Styles (PICTS), Criminal Attitudes to Violence Scale (CAVS), and the Millon Clinical Multiaxial Inventory (MCMI-III and IV) which is designed to assess personality and clinical psychopathology. Standardised residual change scores were used to account for variance in pre-treatment scores, and Cox regression hazard ratios to test prediction of general and violent recidivism.
Most subscales for dynamic risk factor measures and the MCMI-III and IV showed substantial improvements during treatment, however, this did not translate to predicting the probability of recidivism. While several hazard ratios indicated effects in a positive direction, none were significant when adjusted for multiple comparisons, and controlling for actuarial risk did not improve predictive accuracy. There was some evidence of increased socially desirable responding which increased at the end of treatment, this included responses on the MCMI-III and IV consistent with the “Normal Quartet.” Interpretations of these findings and both theoretical and empirical implications are discussed.

text: Does within-treatment change on dynamic risk factors and psychopathology predict recidivism for men graduating from Tai Aroha? Dynamic risk factors are modifiable aspects of justice-involved people and their environment that can change over time and are associated with criminal behaviour. Because they are considered changeable, they are therefore typically the focus of rehabilitative treatment (Bonta & Andrews, 2024). Research shows that correctional rehabilitation that targets dynamic risk factors effectively reduces recidivism, and psychometric tools assessing these factors generally show improvements during treatment. However, there is a missing link; current research lacks consistent evidence linking changes on dynamic risk factors during treatment to recidivism. Relatedly, there are few studies assessing within-treatment changes in psychopathology and how they may affect recidivism, though they are commonly assessed alongside dynamic risk factors in correctional settings. 
This study, involving 164 people with violent offence convictions who completed the Tai Aroha community treatment programme, aimed to address this missing link. A battery of tests measured pre- and post-programme included dynamic risk factor measures, the Anger Disorders Scale (ADS), Psychological Inventory of Criminal Thinking Styles (PICTS), Criminal Attitudes to Violence Scale (CAVS), and the Millon Clinical Multiaxial Inventory (MCMI-III and IV) which is designed to assess personality and clinical psychopathology. Standardised residual change scores were used to account for variance in pre-treatment scores, and Cox regression hazard ratios to test prediction of general and violent recidivism.
Most subscales for dynamic risk factor measures and the MCMI-III and IV showed substantial improvements during treatment, however, this did not translate to predicting the probability of recidivism. While several hazard ratios indicated effects in a positive direction, none were significant when adjusted for multiple comparisons, and controlling for actuarial risk did not improve predictive accuracy. There was some evidence of increased socially desirable responding which increased at the end of treatment, this included responses on the MCMI-III and IV consistent with the “Normal Quartet.” Interpretations of these findings and both theoretical and empirical implications are discussed.

year: 2024-01-23