title: Corrections to Compact Nonlinear Model of an Implantable Electrode Array for Spinal Cord Stimulation

authors: Scott, Jonathan B.

abstract: Reference [1] describes the construction of a model of the electrode-electrolyte interface and the surrounding electrolyte for a platinum-electrode array used in Spinal Cord Stimulation (SCS) applications. In that paper, a key advancement was a compact equivalent-circuit model of a constant phase element (CPE) that can be entered into the SPICE simulator. The authors of [1] relied heavily on mathematics taken from [2] by Morrison. While the mathematics in [2] produces a zero error in phase, it results in a finite error in magnitude. Morrison makes no claim about this error in the magnitude approximation, which escaped the authors of [1]. Morrison does not explain how he arrived at (18), and (19) proves to be incorrect.

text: Corrections to Compact Nonlinear Model of an Implantable Electrode Array for Spinal Cord Stimulation Reference [1] describes the construction of a model of the electrode-electrolyte interface and the surrounding electrolyte for a platinum-electrode array used in Spinal Cord Stimulation (SCS) applications. In that paper, a key advancement was a compact equivalent-circuit model of a constant phase element (CPE) that can be entered into the SPICE simulator. The authors of [1] relied heavily on mathematics taken from [2] by Morrison. While the mathematics in [2] produces a zero error in phase, it results in a finite error in magnitude. Morrison makes no claim about this error in the magnitude approximation, which escaped the authors of [1]. Morrison does not explain how he arrived at (18), and (19) proves to be incorrect.

year: 2018

title: A mass balance evaluation of the ecological significance of historical nitrogen fluxes in Lake Kinneret

authors: Nishri, A.

subjects: nitrate

abstract: Lake Kinneret (LK) is a monomictic lake that has undergone significant biological and chemical changes over the last three decades of the twentieth century. The transition between the 1970s and the 1980s attracted a lot of scientific attention as it was marked by significant changes in the ecology of the lake. In the early 1980s, phytoplankton biomass increased, apparently in response to an increase in the external soluble reactive phosphorus (SRP) load. This period was marked by a rise in hypolimnetic levels of ammonium (NH4) and SRP as well as surface water dissolved oxygen (DO) and pH. Cconcomitantly, in surface waters in winter levels of NH4 increased and NO₃ decreased. In this study interrelationships amongst these observations were examined with a mass balance modelling approach, including simulation of individual nutrient sources and sinks, focusing on nitrogen fluxes in winter. The step-like rise in phytoplankton biomass in 1981 may have been triggered by the increase in winter external loads of SRP, as P is likely to be the growth-limiting nutrient during this season. The additional P load led to a sequence of changes including greater summer phytoplankton biomass, followed by enhanced sedimentation of organic matter. Furthermore, higher organic matter mineralization fluxes within the hypolimnion resulted in elevated levels of NH4 and SRP in this layer through the 1980s, with a feedback to productivity in the trophogenic zone following seasonal destratification in early winter. In an apparent transition period (late 1970s to early 1980s), an increase in the modelled rate of nitrate (NO₃) production occurred via nitrification together with increased uptake of the additional nitrate by phytoplankton. These results are consistent with increased phytoplankton abundance and elevated levels of surface water NH4 and DO during this period. Through this period the increase in phytoplankton uptake of NO₃ predominated over the increase in nitrification, and NO₃ concentrations in the 1980s were reduced compared with the previous decade, with increased partitioning of N in biomass and NH₄.

text: A mass balance evaluation of the ecological significance of historical nitrogen fluxes in Lake Kinneret Lake Kinneret (LK) is a monomictic lake that has undergone significant biological and chemical changes over the last three decades of the twentieth century. The transition between the 1970s and the 1980s attracted a lot of scientific attention as it was marked by significant changes in the ecology of the lake. In the early 1980s, phytoplankton biomass increased, apparently in response to an increase in the external soluble reactive phosphorus (SRP) load. This period was marked by a rise in hypolimnetic levels of ammonium (NH4) and SRP as well as surface water dissolved oxygen (DO) and pH. Cconcomitantly, in surface waters in winter levels of NH4 increased and NO₃ decreased. In this study interrelationships amongst these observations were examined with a mass balance modelling approach, including simulation of individual nutrient sources and sinks, focusing on nitrogen fluxes in winter. The step-like rise in phytoplankton biomass in 1981 may have been triggered by the increase in winter external loads of SRP, as P is likely to be the growth-limiting nutrient during this season. The additional P load led to a sequence of changes including greater summer phytoplankton biomass, followed by enhanced sedimentation of organic matter. Furthermore, higher organic matter mineralization fluxes within the hypolimnion resulted in elevated levels of NH4 and SRP in this layer through the 1980s, with a feedback to productivity in the trophogenic zone following seasonal destratification in early winter. In an apparent transition period (late 1970s to early 1980s), an increase in the modelled rate of nitrate (NO₃) production occurred via nitrification together with increased uptake of the additional nitrate by phytoplankton. These results are consistent with increased phytoplankton abundance and elevated levels of surface water NH4 and DO during this period. Through this period the increase in phytoplankton uptake of NO₃ predominated over the increase in nitrification, and NO₃ concentrations in the 1980s were reduced compared with the previous decade, with increased partitioning of N in biomass and NH₄.

year: 2010

title: The first accurate and precise calendar dating of New Zealand Māori Pā, using Otāhau Pā as a case study.

authors: Hogg, Alan G.

subjects: Māori pā

abstract: This research investigates the potential of radiocarbon wiggle-match dating of palisade posts to provide precise and accurate calendar ages for Māori pā (forts), using Otāhau Pā in the inland Waikato region, New Zealand, as a case study. Even though pā are a dominant element of the pre-European North Island archaeological landscape, they are poorly understood archaeologically, with systematic investigations hampered by the relative lack of precision in radiocarbon dating within the context of New Zealand’s comparatively short prehistory. Using the Southern Hemisphere calibration curve SHCal13, we determine wiggle-match calibrated ages for three palisade posts, using different sampling resolutions to determine the cost- effectiveness of the method. We also test the accuracy of the wiggle-match by obtaining new Southern Hemisphere calibration data from known calendar-age kauri.

text: The first accurate and precise calendar dating of New Zealand Māori Pā, using Otāhau Pā as a case study. This research investigates the potential of radiocarbon wiggle-match dating of palisade posts to provide precise and accurate calendar ages for Māori pā (forts), using Otāhau Pā in the inland Waikato region, New Zealand, as a case study. Even though pā are a dominant element of the pre-European North Island archaeological landscape, they are poorly understood archaeologically, with systematic investigations hampered by the relative lack of precision in radiocarbon dating within the context of New Zealand’s comparatively short prehistory. Using the Southern Hemisphere calibration curve SHCal13, we determine wiggle-match calibrated ages for three palisade posts, using different sampling resolutions to determine the cost- effectiveness of the method. We also test the accuracy of the wiggle-match by obtaining new Southern Hemisphere calibration data from known calendar-age kauri.

year: 2017