title: Barlow Twins for semi-supervised learning in NIR spectroscopy

authors: Wohlers, Mark W.

subjects: Barlow Twins

abstract: Near-infrared (NIR) spectroscopy is a widely used technology in the horticulture industry for non-destructive fruit grading. Partial Least Squares (PLS) regression is the dominant method for producing fruit quality predictions from measured spectra. Alternative deep learning methods have shown promise, but often require large amounts of labelled data to train. This study proposes a semi-supervised method based on Barlow Twins to include unlabelled data in the training process. We adopt the Barlow Twins method by using repeated measurements on the same fruit from different devices as different “views” to encode into the same latent space and combine the encoder network with a regression head for prediction. Our approach demonstrates improved performance over PLS with up to 17% lower RMSE, especially when the labelled data is limited. The Barlow loss function also improves calibration transfer results.

text: Barlow Twins for semi-supervised learning in NIR spectroscopy Near-infrared (NIR) spectroscopy is a widely used technology in the horticulture industry for non-destructive fruit grading. Partial Least Squares (PLS) regression is the dominant method for producing fruit quality predictions from measured spectra. Alternative deep learning methods have shown promise, but often require large amounts of labelled data to train. This study proposes a semi-supervised method based on Barlow Twins to include unlabelled data in the training process. We adopt the Barlow Twins method by using repeated measurements on the same fruit from different devices as different “views” to encode into the same latent space and combine the encoder network with a regression head for prediction. Our approach demonstrates improved performance over PLS with up to 17% lower RMSE, especially when the labelled data is limited. The Barlow loss function also improves calibration transfer results.

year: 2026-02-15

title: Uptake of ΣDDT, arsenic, cadmium, copper, and lead by lettuce and radish grown in contaminated horticultural soils

authors: Gaw, Sally K.

subjects: horticultural soil

abstract: Horticultural soils can contain elevated concentrations of selected trace elements and organochlorine pesticides as a result of long-term use of agrichemicals and soil amendments. A glasshouse study was undertaken to assess the uptake of weathered ΣDDT {sum of the p,p′- and o,p-isomers of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane], DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] and DDD[1,1-dichloro-2,2-bis(p-chlorophenyl)ethane]}, arsenic (As), cadmium (Cd), copper (Cu), and lead (Pb) residues by lettuce (Lactuca sativa) and radish (Raphanus sativus) from field-aged New Zealand horticultural soils. Concentrations of ΣDDT, DDT, DDE, Cd, Cu, and Pb in lettuce increased with increasing soil concentrations. In radish, similar relationships were observed for ΣDDT, DDE, and Cu. The bioaccumulation factors were less than 1 with the exception of Cd and decreased with increasing soil concentrations. Lettuce Cd concentrations for plants grown on four out of 10 assayed soils were equivalent to or exceeded the New Zealand food standard for leafy vegetables of 0.1 mg kg−1 fresh weight. Concentrations of As, Pb, and ΣDDT did not exceed available food standards. Overall, these results demonstrate that aged residues of ΣDDT, As, Cd, Cu, and Pb in horticultural soils have remained phytoavailable. To be protective of human health, site-specific risk assessments and soil guideline derivations for residential settings with vegetable gardens need to consider the produce consumption pathway.

text: Uptake of ΣDDT, arsenic, cadmium, copper, and lead by lettuce and radish grown in contaminated horticultural soils Horticultural soils can contain elevated concentrations of selected trace elements and organochlorine pesticides as a result of long-term use of agrichemicals and soil amendments. A glasshouse study was undertaken to assess the uptake of weathered ΣDDT {sum of the p,p′- and o,p-isomers of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane], DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] and DDD[1,1-dichloro-2,2-bis(p-chlorophenyl)ethane]}, arsenic (As), cadmium (Cd), copper (Cu), and lead (Pb) residues by lettuce (Lactuca sativa) and radish (Raphanus sativus) from field-aged New Zealand horticultural soils. Concentrations of ΣDDT, DDT, DDE, Cd, Cu, and Pb in lettuce increased with increasing soil concentrations. In radish, similar relationships were observed for ΣDDT, DDE, and Cu. The bioaccumulation factors were less than 1 with the exception of Cd and decreased with increasing soil concentrations. Lettuce Cd concentrations for plants grown on four out of 10 assayed soils were equivalent to or exceeded the New Zealand food standard for leafy vegetables of 0.1 mg kg−1 fresh weight. Concentrations of As, Pb, and ΣDDT did not exceed available food standards. Overall, these results demonstrate that aged residues of ΣDDT, As, Cd, Cu, and Pb in horticultural soils have remained phytoavailable. To be protective of human health, site-specific risk assessments and soil guideline derivations for residential settings with vegetable gardens need to consider the produce consumption pathway.

year: 2008

title: Kaum tuatanga the changing roles of kaum tua in Ng ti Rehua: Future directions

authors: Davies, Sydney Henare

subjects: Indigenous psychology

abstract: This study looks at the roles of kaum tua and investigates how these roles have changed over time. With the ageing Māori population and the reported importance of kaum tua roles in the wellbeing of Māori communities, the findings of this study provide an insight into the possible future direction of these roles. The study was conducted with the assistance of members of one hapu (N=47) that were 65 years of age and over. The study was by interview, utilising a semi-structured questionnaire with both open ended and closed questions. Narratives from participants was analysed and compared to the roles of kaum tua that were found in the literature, namely; Leadership, cultural knowledge, dispute resolution, protection and nurturing of young, provide spiritual and other guidance, social control, provide rituals, preserve te reo Māori and live active and healthy lives. Findings of this research supported the roles found in the literature. The roles of kaum tua still exist but may have diminished over time. The change in roles is in the adaptation to meet the needs of the time period while maintaining the core values of each role and providing a continuation of practices.

text: Kaum tuatanga the changing roles of kaum tua in Ng ti Rehua: Future directions This study looks at the roles of kaum tua and investigates how these roles have changed over time. With the ageing Māori population and the reported importance of kaum tua roles in the wellbeing of Māori communities, the findings of this study provide an insight into the possible future direction of these roles. The study was conducted with the assistance of members of one hapu (N=47) that were 65 years of age and over. The study was by interview, utilising a semi-structured questionnaire with both open ended and closed questions. Narratives from participants was analysed and compared to the roles of kaum tua that were found in the literature, namely; Leadership, cultural knowledge, dispute resolution, protection and nurturing of young, provide spiritual and other guidance, social control, provide rituals, preserve te reo Māori and live active and healthy lives. Findings of this research supported the roles found in the literature. The roles of kaum tua still exist but may have diminished over time. The change in roles is in the adaptation to meet the needs of the time period while maintaining the core values of each role and providing a continuation of practices.

year: 2008