title: Spontaneous action potential initiation and propagation in developing cell segments of Acetabularia mediterranea

authors: Thavarungkul, Panote

abstract: The spontaneous action potentials which occur during the redevelopment of anucleate isolated stalk segments (ISS’s) of the unicellular alga Acetabularia mediterranea have been studied using a novel non-invasive technique. This involved measurement of spatial samples of the time dependent potential in the external medium (sea water) and an inverse transformation to give the current distribution at the cell surface. A detailed description of the method of regularization needed to handle this ill-conditioned inversion problem is presented, along with the results of test experiments to demonstrate its validity.
The initiation region and subsequent propagation (if any) of each action potential was then analysed from the computed transmembrane currents. The results showed that the occurrences of the spontaneous action potentials followed a rhythm which had a period of ~24-30 hours. These action potentials initiated more frequently at the ends of the ISS’s than in the middle region. Contrary to the findings of Novak and Bentrup (1972) in which the cell segments had been maintained in unnatural conditions (a partitioned cuvette with electrical isolation between partitions) which could very well have resulted in perturbation of the cell environment, our results show no firm correlation between the regions of action potential initiation and the site of the redeveloping apex. Generally both propagating and non-propagating action potentials were observed in the same ISS, the ratio of which seems to depend on the length of the cell. The analysed initiation sites and the propagation behaviour of the spontaneous action potentials generated by the ISS’s during the redevelopmental process do not provide any support to the symmetry-breaking role of the propagating action potentials as proposed by Novak and Bentrup.

text: Spontaneous action potential initiation and propagation in developing cell segments of Acetabularia mediterranea The spontaneous action potentials which occur during the redevelopment of anucleate isolated stalk segments (ISS’s) of the unicellular alga Acetabularia mediterranea have been studied using a novel non-invasive technique. This involved measurement of spatial samples of the time dependent potential in the external medium (sea water) and an inverse transformation to give the current distribution at the cell surface. A detailed description of the method of regularization needed to handle this ill-conditioned inversion problem is presented, along with the results of test experiments to demonstrate its validity.
The initiation region and subsequent propagation (if any) of each action potential was then analysed from the computed transmembrane currents. The results showed that the occurrences of the spontaneous action potentials followed a rhythm which had a period of ~24-30 hours. These action potentials initiated more frequently at the ends of the ISS’s than in the middle region. Contrary to the findings of Novak and Bentrup (1972) in which the cell segments had been maintained in unnatural conditions (a partitioned cuvette with electrical isolation between partitions) which could very well have resulted in perturbation of the cell environment, our results show no firm correlation between the regions of action potential initiation and the site of the redeveloping apex. Generally both propagating and non-propagating action potentials were observed in the same ISS, the ratio of which seems to depend on the length of the cell. The analysed initiation sites and the propagation behaviour of the spontaneous action potentials generated by the ISS’s during the redevelopmental process do not provide any support to the symmetry-breaking role of the propagating action potentials as proposed by Novak and Bentrup.

year: 1985

title: An evaluation of current and potential technology for the treatment of farm dairy effluent in New Zealand - Assessing the potential to use anaerobic digestion and sequencing batch reactor technology as an alternative method of treatment of  farm dairy effluent

authors: Buchanan, Kendal

subjects: Farm Dairy Effluent

abstract: In order to keep up with social and consumer demands the regulations surrounding nutrient losses from dairy farms in New Zealand are becoming harsher. A way in which dairy farms can reduce the loss of nutrients is to improve the management of farm dairy effluent (FDE). FDE management can be improved by adding a treatment. This treatment may be chemical or biological.
The objective of this research was to develop a method of biological removal of nutrients from farm dairy effluent that enables more efficient management of those nutrients. The system that resulted (BioClean) was a five-stage system including; solids separation, anaerobic digestion, an enhanced biological nutrient removal sequencing batch reactor, sand filtration and UV disinfection.
Modelling of the BioClean system and current methods of FDE handling and treatment, found that BioClean outperformed all current technologies (two pond treatment, land application and ClearTech) in the removal of nitrogen from the liquid fraction (average removal of 98%). The removal of phosphorus and potassium from the liquid fraction were not found to be sufficient for discharge to waterways with average residuals of 13 mg/L and 772 mg/L (Table 32) respectively. Removal of Escherichia coli by BioClean was found to be vary significantly with scenario variation (from a mean of 0 cfu/100ml to 16,260 cfu/100ml).
Analysis of the model found that variation in results could potentially be explained by the model simulation. Therefore, even though scenario and treatment variation were found to be statistically significant (p<0.05) in most cases, the cause of that variation can not confidently be linked to either the treatment change or variable that changed with regards to scenario differences.
Economic analysis of the addition of the BioClean system to a New Zealand dairy farm found that if the desired levels of nutrient removal could be achieved the addition of the BioClean system to a dairy farm was to be viable. The system was found to reduce daily running costs in comparison to the typical land application system due to pumping only the liquid fraction of FDE after solid separation a short distance.

Future research into the BioClean method through a lab-scale trial was recommended to improve the accuracy of the model and optimise the operating system.

text: An evaluation of current and potential technology for the treatment of farm dairy effluent in New Zealand - Assessing the potential to use anaerobic digestion and sequencing batch reactor technology as an alternative method of treatment of  farm dairy effluent In order to keep up with social and consumer demands the regulations surrounding nutrient losses from dairy farms in New Zealand are becoming harsher. A way in which dairy farms can reduce the loss of nutrients is to improve the management of farm dairy effluent (FDE). FDE management can be improved by adding a treatment. This treatment may be chemical or biological.
The objective of this research was to develop a method of biological removal of nutrients from farm dairy effluent that enables more efficient management of those nutrients. The system that resulted (BioClean) was a five-stage system including; solids separation, anaerobic digestion, an enhanced biological nutrient removal sequencing batch reactor, sand filtration and UV disinfection.
Modelling of the BioClean system and current methods of FDE handling and treatment, found that BioClean outperformed all current technologies (two pond treatment, land application and ClearTech) in the removal of nitrogen from the liquid fraction (average removal of 98%). The removal of phosphorus and potassium from the liquid fraction were not found to be sufficient for discharge to waterways with average residuals of 13 mg/L and 772 mg/L (Table 32) respectively. Removal of Escherichia coli by BioClean was found to be vary significantly with scenario variation (from a mean of 0 cfu/100ml to 16,260 cfu/100ml).
Analysis of the model found that variation in results could potentially be explained by the model simulation. Therefore, even though scenario and treatment variation were found to be statistically significant (p<0.05) in most cases, the cause of that variation can not confidently be linked to either the treatment change or variable that changed with regards to scenario differences.
Economic analysis of the addition of the BioClean system to a New Zealand dairy farm found that if the desired levels of nutrient removal could be achieved the addition of the BioClean system to a dairy farm was to be viable. The system was found to reduce daily running costs in comparison to the typical land application system due to pumping only the liquid fraction of FDE after solid separation a short distance.

Future research into the BioClean method through a lab-scale trial was recommended to improve the accuracy of the model and optimise the operating system.

year: 2020

title: Wearable technology for hazardous remote environments: Smart shirt and Rugged IoT network for forestry worker health

authors: Hinze, Annika

subjects: software engineering

abstract: This paper introduces the architecture and details of our wearable IoT solution for workplace health and safety in rugged outdoor environments. We focus on the specific requirements defined by the New Zealand forestry environment as it is the industry with the most fatalities and highest accident rate in New Zealand. Neither consumer-level products nor professional wearables have been found to be suitable for forestry conditions. Furthermore, forestry workplaces cannot rely on existing networking infrastructure, and due to their remote and rugged nature, no permanent setup is possible.

We describe the Hakituri project in which we integrate wearable devices, networking, data analytics, and a buddy system into a novel monitoring solution for worker health and safety. Our wearable IoT solution includes a dynamic network set-up, wearables suitable for forestry conditions, contextual rule-based data analytics, and real-time alerts. A wearable smart shirt carries sensors for collecting personal data from forestry workers, while further environmental sensors capture contextual data. The IoT network is set up for communication in unreliable and rugged outdoor environments. We explore a variety of setups to achieve the best quality outcomes for health and safety in the forestry domain.

text: Wearable technology for hazardous remote environments: Smart shirt and Rugged IoT network for forestry worker health This paper introduces the architecture and details of our wearable IoT solution for workplace health and safety in rugged outdoor environments. We focus on the specific requirements defined by the New Zealand forestry environment as it is the industry with the most fatalities and highest accident rate in New Zealand. Neither consumer-level products nor professional wearables have been found to be suitable for forestry conditions. Furthermore, forestry workplaces cannot rely on existing networking infrastructure, and due to their remote and rugged nature, no permanent setup is possible.

We describe the Hakituri project in which we integrate wearable devices, networking, data analytics, and a buddy system into a novel monitoring solution for worker health and safety. Our wearable IoT solution includes a dynamic network set-up, wearables suitable for forestry conditions, contextual rule-based data analytics, and real-time alerts. A wearable smart shirt carries sensors for collecting personal data from forestry workers, while further environmental sensors capture contextual data. The IoT network is set up for communication in unreliable and rugged outdoor environments. We explore a variety of setups to achieve the best quality outcomes for health and safety in the forestry domain.

year: 2022