title: Crossing the symbolic threshold: a critical review of Terrence Deacon's The Symbolic Species

authors: Lumsden, David

abstract: Terrence Deacon's views about the origin of language are based on a particular notion of a symbol. While the notion is derived from Peirce's semiotics, it diverges from that source and needs to be investigated on its own terms in order to evaluate the idea that the human species has crossed the symbolic threshold. Deacon's view is defended from the view that symbols in the animal world are widespread and from the extreme connectionist view that they are not even to be found in humans.  Deacon's treatment of symbols involves a form of holism, as a symbol needs to be part of a system of symbols. He also appears to take a realist view of symbols.  That combination of holism and realism makes the threshold a sharp threshold, which makes it hard to explain how the threshold was crossed.  This difficulty is overcome if we take a mild realist position towards symbols, in the style of Dennett. Mild realism allows intermediate stages in the crossing but does not undermine Deacon's claim that the threshold is difficult to cross or the claim that it needs to be crossed quickly.

text: Crossing the symbolic threshold: a critical review of Terrence Deacon's The Symbolic Species Terrence Deacon's views about the origin of language are based on a particular notion of a symbol. While the notion is derived from Peirce's semiotics, it diverges from that source and needs to be investigated on its own terms in order to evaluate the idea that the human species has crossed the symbolic threshold. Deacon's view is defended from the view that symbols in the animal world are widespread and from the extreme connectionist view that they are not even to be found in humans.  Deacon's treatment of symbols involves a form of holism, as a symbol needs to be part of a system of symbols. He also appears to take a realist view of symbols.  That combination of holism and realism makes the threshold a sharp threshold, which makes it hard to explain how the threshold was crossed.  This difficulty is overcome if we take a mild realist position towards symbols, in the style of Dennett. Mild realism allows intermediate stages in the crossing but does not undermine Deacon's claim that the threshold is difficult to cross or the claim that it needs to be crossed quickly.

year: 2002-06-01

title: Estimation of photovoltaic conversion efficiency of a building integrated photovoltaic/thermal (BIPV/T) collector array using an artificial neural network

authors: Ghani, Faisal Abid

subjects: artificial neural network

abstract: Earlier studies have shown that the thermal efficiency of a solar thermal collector is influenced by the quality of coolant flow distribution within the array. The quality of flow distribution within a header/riser type fluid network is influenced by a number of parameters including the coolant mass flow rate, the direction of flow in the manifolds, and most importantly the geometry of the array. As a building integrated photovoltaic thermal (BIPVT) collector will be a made to measure product, meaning its dimensions will be dictated by the specific roofing and energy requirements of the customer, the issue of flow distribution and its effect on both thermal and photovoltaic performance raises some concern. In order to quantify the detrimental effect flow distribution may have on the photovoltaic output of a BIPVT array, a numerical approach was presented by authors in earlier work where factors known to influence flow distribution were varied. The authors demonstrated that photovoltaic output may be severely hindered if the issue of flow distribution is not adequately addressed. In this new study we use this numerical method to additionally show that photovoltaic output is not always improved by reducing the fin width W (by increasing the number of risers for each module) despite the theoretical rise in fin efficiency F as a consequence of flow distribution. Under certain scenarios it was shown that a single riser will in fact improve PV output and also reduce system installation cost and complexity. The combination of these new finding and results previously obtained by the authors highlights the need in selecting the optimal design parameters to meet the specific requirements of each installation. The numerical approach carried out to calculate PV output however was time consuming and computationally intensive and therefore not feasible to perform for each and every customer. To address this issue, the authors have proposed in this paper to train an artificial neural network which can be used to approximate the photovoltaic yield of an array of specified shape operating under parallel{minus 45 degree rule}reverse flow in the manifolds and also with one or two fluid channels cooling each string of cells. By approximating the yield for each scenario, the optimal configuration can then be chosen. It was found that the neural network can be successfully trained for this specific application offering a fast alternative to the original numerical approach.

text: Estimation of photovoltaic conversion efficiency of a building integrated photovoltaic/thermal (BIPV/T) collector array using an artificial neural network Earlier studies have shown that the thermal efficiency of a solar thermal collector is influenced by the quality of coolant flow distribution within the array. The quality of flow distribution within a header/riser type fluid network is influenced by a number of parameters including the coolant mass flow rate, the direction of flow in the manifolds, and most importantly the geometry of the array. As a building integrated photovoltaic thermal (BIPVT) collector will be a made to measure product, meaning its dimensions will be dictated by the specific roofing and energy requirements of the customer, the issue of flow distribution and its effect on both thermal and photovoltaic performance raises some concern. In order to quantify the detrimental effect flow distribution may have on the photovoltaic output of a BIPVT array, a numerical approach was presented by authors in earlier work where factors known to influence flow distribution were varied. The authors demonstrated that photovoltaic output may be severely hindered if the issue of flow distribution is not adequately addressed. In this new study we use this numerical method to additionally show that photovoltaic output is not always improved by reducing the fin width W (by increasing the number of risers for each module) despite the theoretical rise in fin efficiency F as a consequence of flow distribution. Under certain scenarios it was shown that a single riser will in fact improve PV output and also reduce system installation cost and complexity. The combination of these new finding and results previously obtained by the authors highlights the need in selecting the optimal design parameters to meet the specific requirements of each installation. The numerical approach carried out to calculate PV output however was time consuming and computationally intensive and therefore not feasible to perform for each and every customer. To address this issue, the authors have proposed in this paper to train an artificial neural network which can be used to approximate the photovoltaic yield of an array of specified shape operating under parallel{minus 45 degree rule}reverse flow in the manifolds and also with one or two fluid channels cooling each string of cells. By approximating the yield for each scenario, the optimal configuration can then be chosen. It was found that the neural network can be successfully trained for this specific application offering a fast alternative to the original numerical approach.

year: 2012

title: Assessment of impacts of mechanical spat harvesting on the surf clams of Te Oneroa a Tōhē

authors: Ross, Philip M.

abstract: Much of the mussel spat used to seed mussel aquaculture farms throughout New Zealand is sourced from Te Oneroa a Tōhē (90 Mile Beach) in Te Hiku (far north of New Zealand). The mussel spat washes ashore attached to seaweed and hydroids where it is collected by spat harvesters and transported to mussel farms around the country to be on-grown. The collection of Te Hiku spat and seaweed was originally done by hand. However, the methods used have evolved over time and mussel spat is now primarily collected using mechanical loaders operating in the surf zone. Local iwi, hapu and the wider community have recently voiced their concerns about the impacts of this harvesting method. Specifically, there are concerns about the impact of loaders operating on top of toheroa (Paphies ventricosa) and tuatua (Paphies subtriangulata) beds or other shellfish inhabiting in the intertidal and subtidal areas of Te Oneroa a Tōhē. Consequently, research into the ecological impacts of mechanical spat harvesting was conducted to address the concerns of the community and inform the management of the Te Hiku spat fishery. 
This research aimed to examine the ecological impacts of a ‘worst case scenario’ by (1) simulating an intensity of spat harvesting activity much greater than would be anticipated in the ‘real world’ and (2) conducting the research at high density tuatua beds where impacts would potentially be greatest. Adult toheroa were not targeted in the experiment to avoid unnecessary impacts on already depleted toheroa populations. At each of three sites on Te Oneroa a Tōhē, nine spat harvesting loaders were repeatedly driven in and out of the surf, over shellfish beds, for 75 minutes leading up to the low tide. Once loader activity ceased, a sampling team made up of mana whenua, local primary school children, spat harvesters and staff from MPI, Te Ohu Kaimoana and the University of Waikato collected clams from the intertidal area. Collections were made from both impact and control (non-impact) sites, where (a) the number of crushed shells was quantified and (b) the self-righting and burying abilities of tuatua from impact and control areas were compared to provide an estimate of sub-lethal effects. 
There was no detectable impact of mechanical spat harvesting loaders on tuatua (or the juvenile toheroa that were present in the sampled tuatua beds) when these surf clams were either fully or partially buried in sands of Te Oneroa a Tōhē. Rates of shell damage were less 2 than 6.1% and were similar in impact and control areas indicating much of the observed shell damage was caused by the sediment corers that were used to extract samples from the beach. Similarly, being driven over by loaders did not affect the ability or speed at which tuatua were able to right and bury themselves in the sediment. When standing on end these clams appear robust to the forces exerted by loaders upon the sediment surface. However, beach cast clams (both tuatua and toheroa), lying on top of the sediment on their sides are vulnerable to crushing by vehicles. This includes juvenile clams that ‘float’ to the beach surface where multiple loader passes liquefy the surface sediment. Mortality in these beach cast clams was not well captured by the sampling methodology used in this study, but was observed at two of the three sites sampled. It was not possible to quantify this type of mortality during this study. However, the number of clams crushed on the beach surface was small relative to the high abundances of clams within the sediment and the impact is not considered ecologically significant at the scale the individual shellfish beds or the entire beach. 
Overall, there was nothing observed during the course of this experiment to suggest that mechanical harvesting is having a significant ecological effect on the toheroa or tuatua of Te Oneroa a Tōhē. Mechanical spat harvesting did result in some clam mortality during the course of this experiment, and it is likely that some mortality will occur in the future when clams are present on the beach surface. However, the level of mortality observed, and anticipated, is unlikely to compromise the viability of either clam species. 
To minimise clam mortality caused by spat harvesting, loader operators should endeavour to avoid areas where large numbers of surf clams are either beach cast or are observed washing around in the shallow subtidal. It would also be prudent, because of the depressed state of toheroa populations on Te Oneroa a Tōhē, for spat harvesters to have up-to-date information about the location of toheroa beds and avoid them where possible. 
It should be noted that concerns have been raised as to whether the driving of loaders during this study was equivalent to real world operations. However, the collection of operational data during this experiment, the proposed installation of GPS trackers on all loaders and the use of observers will allow for monitoring and enforcement of operating procedures established in the industry code of practise.

text: Assessment of impacts of mechanical spat harvesting on the surf clams of Te Oneroa a Tōhē Much of the mussel spat used to seed mussel aquaculture farms throughout New Zealand is sourced from Te Oneroa a Tōhē (90 Mile Beach) in Te Hiku (far north of New Zealand). The mussel spat washes ashore attached to seaweed and hydroids where it is collected by spat harvesters and transported to mussel farms around the country to be on-grown. The collection of Te Hiku spat and seaweed was originally done by hand. However, the methods used have evolved over time and mussel spat is now primarily collected using mechanical loaders operating in the surf zone. Local iwi, hapu and the wider community have recently voiced their concerns about the impacts of this harvesting method. Specifically, there are concerns about the impact of loaders operating on top of toheroa (Paphies ventricosa) and tuatua (Paphies subtriangulata) beds or other shellfish inhabiting in the intertidal and subtidal areas of Te Oneroa a Tōhē. Consequently, research into the ecological impacts of mechanical spat harvesting was conducted to address the concerns of the community and inform the management of the Te Hiku spat fishery. 
This research aimed to examine the ecological impacts of a ‘worst case scenario’ by (1) simulating an intensity of spat harvesting activity much greater than would be anticipated in the ‘real world’ and (2) conducting the research at high density tuatua beds where impacts would potentially be greatest. Adult toheroa were not targeted in the experiment to avoid unnecessary impacts on already depleted toheroa populations. At each of three sites on Te Oneroa a Tōhē, nine spat harvesting loaders were repeatedly driven in and out of the surf, over shellfish beds, for 75 minutes leading up to the low tide. Once loader activity ceased, a sampling team made up of mana whenua, local primary school children, spat harvesters and staff from MPI, Te Ohu Kaimoana and the University of Waikato collected clams from the intertidal area. Collections were made from both impact and control (non-impact) sites, where (a) the number of crushed shells was quantified and (b) the self-righting and burying abilities of tuatua from impact and control areas were compared to provide an estimate of sub-lethal effects. 
There was no detectable impact of mechanical spat harvesting loaders on tuatua (or the juvenile toheroa that were present in the sampled tuatua beds) when these surf clams were either fully or partially buried in sands of Te Oneroa a Tōhē. Rates of shell damage were less 2 than 6.1% and were similar in impact and control areas indicating much of the observed shell damage was caused by the sediment corers that were used to extract samples from the beach. Similarly, being driven over by loaders did not affect the ability or speed at which tuatua were able to right and bury themselves in the sediment. When standing on end these clams appear robust to the forces exerted by loaders upon the sediment surface. However, beach cast clams (both tuatua and toheroa), lying on top of the sediment on their sides are vulnerable to crushing by vehicles. This includes juvenile clams that ‘float’ to the beach surface where multiple loader passes liquefy the surface sediment. Mortality in these beach cast clams was not well captured by the sampling methodology used in this study, but was observed at two of the three sites sampled. It was not possible to quantify this type of mortality during this study. However, the number of clams crushed on the beach surface was small relative to the high abundances of clams within the sediment and the impact is not considered ecologically significant at the scale the individual shellfish beds or the entire beach. 
Overall, there was nothing observed during the course of this experiment to suggest that mechanical harvesting is having a significant ecological effect on the toheroa or tuatua of Te Oneroa a Tōhē. Mechanical spat harvesting did result in some clam mortality during the course of this experiment, and it is likely that some mortality will occur in the future when clams are present on the beach surface. However, the level of mortality observed, and anticipated, is unlikely to compromise the viability of either clam species. 
To minimise clam mortality caused by spat harvesting, loader operators should endeavour to avoid areas where large numbers of surf clams are either beach cast or are observed washing around in the shallow subtidal. It would also be prudent, because of the depressed state of toheroa populations on Te Oneroa a Tōhē, for spat harvesters to have up-to-date information about the location of toheroa beds and avoid them where possible. 
It should be noted that concerns have been raised as to whether the driving of loaders during this study was equivalent to real world operations. However, the collection of operational data during this experiment, the proposed installation of GPS trackers on all loaders and the use of observers will allow for monitoring and enforcement of operating procedures established in the industry code of practise.

year: 2020