title: Using acoustic backscatter data to provide estimates of profiles of suspended sediment concentrations for cohesive particles in the field

authors: Redder, Isabella Julie

subjects: Acoustic backscatter

abstract: Many estuaries and rivers in New Zealand and other locations worldwide are stressed by the input of fine (muddy) sediments. Suspended sediment concentrations (SSC) are often used as a key indicator of water quality and are a critical variable in management practices to aid in the health of estuarine habitats. However, robust measurements of SSC are difficult to obtain, owing in part to large gradients in conditions, and the process of ‘flocculation’ or aggregation of fine particles. Amongst the range of measurement tools available, acoustic backscatter (ABS) sensors offer significant potential to provide temporally and spatially well resolved profiles of SSC from the field. The process of ‘inversion’ or converting the acoustic backscatter signal into SSC is effective when all terms are known within the theoretical context. However, the challenge facing the use of ABS technology in the field, is the scattering properties, the form function f∞ and the total scattering cross-section Σₛ, of cohesive particles typical in estuarine environments, are unknown.

For this study, a unique laboratory calibration combined with ABS field data from a mudflat, were used to investigate if a pair of f∞ and Σₛ values could be evaluated for finer grain, mud material as opposed to sand particles. The derived f∞ and Σₛ values appeared to be influenced by other physical controls from the field environment and were sensitive to several assumptions made in the inversion equation. Nonetheless, the acoustic data yielded reasonable estimates of SSC in a field setting, when compared to discrete single-point measurements of SSC obtained from a calibrated optical backscatter sensor. However, there were also times when the inversion methodology did not work well (particularly for acoustic transducers with lower frequencies). Moreover, inversion results were better when using time-varying values for f∞ and Σₛ, the inversion procedure implemented with a universal set parameters did not perform as well. These results imply more research is needed in gathering better descriptions of the f∞ and Σₛ values from multiple ABS frequencies, to improve inversion SSC results from the field.

text: Using acoustic backscatter data to provide estimates of profiles of suspended sediment concentrations for cohesive particles in the field Many estuaries and rivers in New Zealand and other locations worldwide are stressed by the input of fine (muddy) sediments. Suspended sediment concentrations (SSC) are often used as a key indicator of water quality and are a critical variable in management practices to aid in the health of estuarine habitats. However, robust measurements of SSC are difficult to obtain, owing in part to large gradients in conditions, and the process of ‘flocculation’ or aggregation of fine particles. Amongst the range of measurement tools available, acoustic backscatter (ABS) sensors offer significant potential to provide temporally and spatially well resolved profiles of SSC from the field. The process of ‘inversion’ or converting the acoustic backscatter signal into SSC is effective when all terms are known within the theoretical context. However, the challenge facing the use of ABS technology in the field, is the scattering properties, the form function f∞ and the total scattering cross-section Σₛ, of cohesive particles typical in estuarine environments, are unknown.

For this study, a unique laboratory calibration combined with ABS field data from a mudflat, were used to investigate if a pair of f∞ and Σₛ values could be evaluated for finer grain, mud material as opposed to sand particles. The derived f∞ and Σₛ values appeared to be influenced by other physical controls from the field environment and were sensitive to several assumptions made in the inversion equation. Nonetheless, the acoustic data yielded reasonable estimates of SSC in a field setting, when compared to discrete single-point measurements of SSC obtained from a calibrated optical backscatter sensor. However, there were also times when the inversion methodology did not work well (particularly for acoustic transducers with lower frequencies). Moreover, inversion results were better when using time-varying values for f∞ and Σₛ, the inversion procedure implemented with a universal set parameters did not perform as well. These results imply more research is needed in gathering better descriptions of the f∞ and Σₛ values from multiple ABS frequencies, to improve inversion SSC results from the field.

year: 2023

title: The impact of a product-harm crisis on marketing effectiveness

authors: van Heerde, Harald J.

subjects: brand management

abstract: Product-harm crises are among a firm’s worst nightmares. A firm may experience (i) a loss in baseline sales, (ii) a reduced own effectiveness for its marketing instruments, (iii) an increased cross sensitivity to rival firms’ marketing-mix activities, and (iv) a decreased cross impact of its marketing-mix instruments on the sales of competing, unaffected brands. We find that this quadruple jeopardy materialized in a case study of an Australian product-harm crisis faced by Kraft peanut butter. We arrive at this conclusion by using a time-varying error-correction model that quantifies the consequences of this crisis on base sales, and on own- and cross-brand short- and long-term effectiveness. The proposed modeling approach allows managers to make more informed decisions on how to regain the brands’ pre-crisis performance levels.

text: The impact of a product-harm crisis on marketing effectiveness Product-harm crises are among a firm’s worst nightmares. A firm may experience (i) a loss in baseline sales, (ii) a reduced own effectiveness for its marketing instruments, (iii) an increased cross sensitivity to rival firms’ marketing-mix activities, and (iv) a decreased cross impact of its marketing-mix instruments on the sales of competing, unaffected brands. We find that this quadruple jeopardy materialized in a case study of an Australian product-harm crisis faced by Kraft peanut butter. We arrive at this conclusion by using a time-varying error-correction model that quantifies the consequences of this crisis on base sales, and on own- and cross-brand short- and long-term effectiveness. The proposed modeling approach allows managers to make more informed decisions on how to regain the brands’ pre-crisis performance levels.

year: 2007

title: Health information research privacy standards should include Māori perspectives on privacy

authors: Ragupathy, Rajan

subjects: computer science

abstract: Secondary research using health records and other personal health data (henceforth referred to as health information research) is a valuable tool for tackling New Zealand’s health and social challenges. It requires however suitable privacy standards to maintain public confi dence and social license. The privacy protocols used by New Zealand district health boards have been described in this journal, as have additional safeguards that could be adopted to prevent privacy breaches.¹,²

text: Health information research privacy standards should include Māori perspectives on privacy Secondary research using health records and other personal health data (henceforth referred to as health information research) is a valuable tool for tackling New Zealand’s health and social challenges. It requires however suitable privacy standards to maintain public confi dence and social license. The privacy protocols used by New Zealand district health boards have been described in this journal, as have additional safeguards that could be adopted to prevent privacy breaches.¹,²

year: 2019