title: Supercapacitor-based pulse generator with waveform adjustment capability for small animal transcranial magnetic stimulation

authors: Raju, Soniya

subjects: Pulse circuits

abstract: In transcranial magnetic stimulation (TMS), pulsed magnetic fields are applied to the brain, typically requiring high-power stimulators with high voltages and low series impedance. TMS pulse generators for small animal coils, are underexplored, with limited dedicated circuits and simulation models. Here, we present a new design for a high-power TMS pulse generator for small animals, utilizing a pre-charged supercapacitor that is sufficient to produce repeated pulses for TMS applications without the need for recharging. This approach eliminates the need for expensive high-voltage components and a high-voltage power supply. In this paper, we detail the design approach and basic block diagrams of a supercapacitor (SC) based TMS pulse generator, along with its experimental results. The findings indicate that the new circuit enables a complete test using just a single charge of an SC module. The proposed circuit functions as a versatile pulse-shaping device, where the MOSFET is treated as a dynamically varying resistor element rather than a traditional switch; allowing pulse parameter variations. We analyze a novel circuit for generating and controlling TMS pulses in small animal coils, and demonstrate its effectiveness through experimental results.

text: Supercapacitor-based pulse generator with waveform adjustment capability for small animal transcranial magnetic stimulation In transcranial magnetic stimulation (TMS), pulsed magnetic fields are applied to the brain, typically requiring high-power stimulators with high voltages and low series impedance. TMS pulse generators for small animal coils, are underexplored, with limited dedicated circuits and simulation models. Here, we present a new design for a high-power TMS pulse generator for small animals, utilizing a pre-charged supercapacitor that is sufficient to produce repeated pulses for TMS applications without the need for recharging. This approach eliminates the need for expensive high-voltage components and a high-voltage power supply. In this paper, we detail the design approach and basic block diagrams of a supercapacitor (SC) based TMS pulse generator, along with its experimental results. The findings indicate that the new circuit enables a complete test using just a single charge of an SC module. The proposed circuit functions as a versatile pulse-shaping device, where the MOSFET is treated as a dynamically varying resistor element rather than a traditional switch; allowing pulse parameter variations. We analyze a novel circuit for generating and controlling TMS pulses in small animal coils, and demonstrate its effectiveness through experimental results.

year: 2024

title: Strangles: The Molecular Identification and Epidemiology of Streptococcus equi subsp. equi

authors: Patty, Olivia Anne

subjects: strangles

abstract: A conventional PCR diagnostic test was established to confirm the microbiological isolation of Streptococcus equi subsp. equi (S. equi), the causative agent of strangles. This test was based on the amplification of the seeI gene, which is species-specific for S. equi. Further, a multiplex PCR was developed using species-specific primers; to identify the presence of S. equi and two other streptococci know complicate the diagnosis of strangles in horses, Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) and Streptococcus dysgalactiae subsp. equisimilis (S. equisimilis). A total of 18 clinical isolates of S. equi plus the Pinnacle IN vaccine isolate, two isolates of S. zooepidemicus and four isolates of S. equisimilis were obtained via culture and used in the development of the multiplex diagnostic tool. Two multiplex tests were trialed; a conventional multiplex PCR and a real-time multiplex PCR.

Both the conventional and real-time multiplex PCR’s were able to distinguish between the streptococci and accurately identified all isolates. However, further testing on 26 field specimens revealed that the real-time multiplex PCR had lower specificity, sensitivity and diagnostic accuracy as compared to the conventional multiplex PCR. This was theorised to be the result of the PEG/KOH solution used in the DNA extraction, possibly interfering with the intercalating dye in the real-time reaction. Based on these preliminary results, the conventional multiplex PCR diagnostic test developed here is recommended for further trials to determine its robustness.

The 19 S. equi isolates obtained, including the vaccine, were further subjected to epidemiological studies. These included sequencing of the variable N-terminal region of the antiphagocytic M-protein SeM to determine SeM allele subtypes and a Sau-PCR amplification method, which previously has not been trialled on S. equi isolates. Sau-PCR involves digestion of genomic DNA and subsequent amplification. Two novel strains of S. equi were found within NZ based on the variable region of the seM gene, SeM alleles 99 and 100. SeM allele 100 had a higher pervalance over allele 99 as it was isolated in 6 out of 9 outbreaks and was found to occur on both the North and South Islands of New Zealand. SeM allele 99 was only found to occur on the North Island. Further to this study, the Pinnacle IN vaccine strain, SeM 2 was isolated from lymph node abcesses of two horses. It was unclear as to whether this ‘vaccine breakdown’ was just a severe adverse reaction to the vaccine or if the vaccine reverted to a more virulent type. The Sau-PCR was able to differentiate between the field isolates of S. equi and the vaccine strain but was unable to further differentiate between the field isolates and was therefore determined not as valuable for S. equi epidemiological studies.

text: Strangles: The Molecular Identification and Epidemiology of Streptococcus equi subsp. equi A conventional PCR diagnostic test was established to confirm the microbiological isolation of Streptococcus equi subsp. equi (S. equi), the causative agent of strangles. This test was based on the amplification of the seeI gene, which is species-specific for S. equi. Further, a multiplex PCR was developed using species-specific primers; to identify the presence of S. equi and two other streptococci know complicate the diagnosis of strangles in horses, Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) and Streptococcus dysgalactiae subsp. equisimilis (S. equisimilis). A total of 18 clinical isolates of S. equi plus the Pinnacle IN vaccine isolate, two isolates of S. zooepidemicus and four isolates of S. equisimilis were obtained via culture and used in the development of the multiplex diagnostic tool. Two multiplex tests were trialed; a conventional multiplex PCR and a real-time multiplex PCR.

Both the conventional and real-time multiplex PCR’s were able to distinguish between the streptococci and accurately identified all isolates. However, further testing on 26 field specimens revealed that the real-time multiplex PCR had lower specificity, sensitivity and diagnostic accuracy as compared to the conventional multiplex PCR. This was theorised to be the result of the PEG/KOH solution used in the DNA extraction, possibly interfering with the intercalating dye in the real-time reaction. Based on these preliminary results, the conventional multiplex PCR diagnostic test developed here is recommended for further trials to determine its robustness.

The 19 S. equi isolates obtained, including the vaccine, were further subjected to epidemiological studies. These included sequencing of the variable N-terminal region of the antiphagocytic M-protein SeM to determine SeM allele subtypes and a Sau-PCR amplification method, which previously has not been trialled on S. equi isolates. Sau-PCR involves digestion of genomic DNA and subsequent amplification. Two novel strains of S. equi were found within NZ based on the variable region of the seM gene, SeM alleles 99 and 100. SeM allele 100 had a higher pervalance over allele 99 as it was isolated in 6 out of 9 outbreaks and was found to occur on both the North and South Islands of New Zealand. SeM allele 99 was only found to occur on the North Island. Further to this study, the Pinnacle IN vaccine strain, SeM 2 was isolated from lymph node abcesses of two horses. It was unclear as to whether this ‘vaccine breakdown’ was just a severe adverse reaction to the vaccine or if the vaccine reverted to a more virulent type. The Sau-PCR was able to differentiate between the field isolates of S. equi and the vaccine strain but was unable to further differentiate between the field isolates and was therefore determined not as valuable for S. equi epidemiological studies.

year: 2012

title: Ngā tohu o te taiao: Observing signs of the natural world to identify seastar over-abundance as a detriment to shellfish survival in Ōhiwa Harbour, Aotearoa New Zealand

authors: Paul-Burke, Kura

subjects: Tohu

abstract: Māori understandings and experiences of the natural world encompass not only what is known but how it is known, and the intergenerational connectedness of that knowledge with the environments from which it is derived. Ngā tohu o te taiao (hereafter ‘tohu’), or the cultural and environmental signs and indicators of the natural world, are widely used by kaitiaki or local practitioners to identify trends or changes in the state or health of marine taonga (culturally important) species and their associated environments (Paul-Burke, 2017). Māori worldviews position humans within nature and focus on ways in which cultural understandings and intergenerational connections between people and their bio-physical contexts assist in the retention and protection of biodiversity and ecologically sustainable ecosystems (Lyver et al., 2016). Tohu are a fundamental expression of kaitiakitanga or active guardianship and are based on the primal instinct of survival and recognising that in order to survive one must pay attention to the natural signs and signals thoughtfully, so as to manage our mahinga kai (food harvesting area) and ourselves into the future (Paul-Burke et al., 2020). This article considers the example of the over-abundant eleven-armed seastar (pātangaroa, Coscinasterias muricata; hereafter ‘seastar’) predating on culturally and ecologically important shellfish populations in a traditional mahinga kai of Ōhiwa Harbour in the Bay of Plenty region of Aotearoa/New Zealand. The over-abundance of seastars was considered a contemporary tohu of a degrading harbour. It was deemed imperative by iwi (tribe) members that a trial using quantitative methods to investigate predation pressure of seastars on the green-lipped mussel (kuku or kūtai, Perna canaliculus) population be conducted in the harbour. Between September 2018 and February 2019 field trials were undertaken that prioritised mātauranga Māori (Māori knowledge) alongside marine science to assist with a better understanding of the degrading harbour. It was hoped that the research would help and promote recovery, in particular but not limited to, the once abundant but now severely reduced mussel reefs in the soft-mud-bottomed harbour.

text: Ngā tohu o te taiao: Observing signs of the natural world to identify seastar over-abundance as a detriment to shellfish survival in Ōhiwa Harbour, Aotearoa New Zealand Māori understandings and experiences of the natural world encompass not only what is known but how it is known, and the intergenerational connectedness of that knowledge with the environments from which it is derived. Ngā tohu o te taiao (hereafter ‘tohu’), or the cultural and environmental signs and indicators of the natural world, are widely used by kaitiaki or local practitioners to identify trends or changes in the state or health of marine taonga (culturally important) species and their associated environments (Paul-Burke, 2017). Māori worldviews position humans within nature and focus on ways in which cultural understandings and intergenerational connections between people and their bio-physical contexts assist in the retention and protection of biodiversity and ecologically sustainable ecosystems (Lyver et al., 2016). Tohu are a fundamental expression of kaitiakitanga or active guardianship and are based on the primal instinct of survival and recognising that in order to survive one must pay attention to the natural signs and signals thoughtfully, so as to manage our mahinga kai (food harvesting area) and ourselves into the future (Paul-Burke et al., 2020). This article considers the example of the over-abundant eleven-armed seastar (pātangaroa, Coscinasterias muricata; hereafter ‘seastar’) predating on culturally and ecologically important shellfish populations in a traditional mahinga kai of Ōhiwa Harbour in the Bay of Plenty region of Aotearoa/New Zealand. The over-abundance of seastars was considered a contemporary tohu of a degrading harbour. It was deemed imperative by iwi (tribe) members that a trial using quantitative methods to investigate predation pressure of seastars on the green-lipped mussel (kuku or kūtai, Perna canaliculus) population be conducted in the harbour. Between September 2018 and February 2019 field trials were undertaken that prioritised mātauranga Māori (Māori knowledge) alongside marine science to assist with a better understanding of the degrading harbour. It was hoped that the research would help and promote recovery, in particular but not limited to, the once abundant but now severely reduced mussel reefs in the soft-mud-bottomed harbour.

year: 2022-03-28