Heuristic Spike Sorting Tuner (HSST), a framework to determine optimal parameter selection for a generic spike sorting algorithm

Extracellular microelectrodes frequently record neural activity from more than one neuron in the vicinity of the electrode. The process of labeling each recorded spike waveform with the identity of its source neuron is called spike sorting and is often approached from an abstracted statistical perspective. However, these approaches do not consider neurophysiological realities and may ignore important features that could improve the accuracy of these methods. Further, standard algorithms typically require selection of at least one free parameter, which can have significant effects on the quality of the output. We describe a Heuristic Spike Sorting Tuner (HSST) that determines the optimal choice of the free parameters for a given spike sorting algorithm based on the neurophysiological qualification of unit isolation and signal discrimination. A set of heuristic metrics are used to score the output of a spike sorting algorithm over a range of free parameters resulting in optimal sorting quality. We demonstrate that these metrics can be used to tune parameters in several spike sorting algorithms. The HSST algorithm shows robustness to variations in signal to noise ratio, number and relative size of units per channel. Moreover, the HSST algorithm is computationally efficient, operates unsupervised, and is parallelizable for batch processing

Work Values, Travel Satisfaction, and Organizational Injustice as Antecedents of Corporate Travel Policy Compliance

Despite the Covid-19 pandemic, business travel spending is expected to reach two-thirds of the pre-pandemic levels in 2022. Therefore, travel policies remain essential for reducing travel expenses and managing traveller behaviour. A significant challenge for a company is to ensure compliance with its travel policy. This study uses the equity theory and person-organization fit model to understand non-compliance with travel policies. Two hundred and five responses were collected from corporate travellers employed in South Africa via an online survey. The results revealed that work values and perceived organizational injustice could influence corporate travel policy compliance. This study is the first to investigate the influence of work values, travel satisfaction, and organizational injustice on unethical decision-making and behaviour in a corporate travel context

Uncapped Potential: Applying Firearms Identification Procedures in the Analysis of Percussion Caps

Firearms identification procedures continue to playa role in the archaeological study of battles and warfare. Percussion caps, if well preserved, have the potential to yield unique individual tool marks that can be microscopically examined to determine a minimum number of weapons present at a specific site. This study analyzed 110 percussion caps from an 1854 U.S. Army and Apache battle site and determined that at least 34 firearms were used in the battle. A valida- tion study using modern percussion caps from 11 known weapons was also undertaken to demonstrate the potential for percussion cap analysis in future studies

SNTF immunostaining reveals previously undetected axonal pathology in traumatic brain injury

Diffuse axonal injury (DAI) is a common feature of severe traumatic brain injury (TBI) and may also be a predominant pathology in mild TBI or “concussion”. The rapid deformation of white matter at the instant of trauma can lead to mechanical failure and calcium-dependent proteolysis of the axonal cytoskeleton in association with axonal transport interruption. Recently, a proteolytic fragment of alpha-II spectrin, “SNTF”, was detected in serum acutely following mild TBI in patients and was prognostic for poor clinical outcome. However, direct evidence that this fragment is a marker of DAI has yet to be demonstrated in either humans following TBI or in models of mild TBI. Here, we used immunohistochemistry (IHC) to examine for SNTF in brain tissue following both severe and mild TBI. Human severe TBI cases (survival <7d; n = 18) were compared to age-matched controls (n = 16) from the Glasgow TBI archive. We also examined brains from an established model of mild TBI at 6, 48 and 72 h post-injury versus shams. IHC specific for SNTF was compared to that of amyloid precursor protein (APP), the current standard for DAI diagnosis, and other known markers of axonal pathology including non-phosphorylated neurofilament-H (SMI-32), neurofilament-68 (NF-68) and compacted neurofilament-medium (RMO-14) using double and triple immunofluorescent labeling. Supporting its use as a biomarker of DAI, SNTF immunoreactive axons were observed at all time points following both human severe TBI and in the model of mild TBI. Interestingly, SNTF revealed a subpopulation of degenerating axons, undetected by the gold-standard marker of transport interruption, APP. While there was greater axonal co-localization between SNTF and APP after severe TBI in humans, a subset of SNTF positive axons displayed no APP accumulation. Notably, some co-localization was observed between SNTF and the less abundant neurofilament subtype markers. Other SNTF positive axons, however, did not co-localize with any other markers. Similarly, RMO-14 and NF-68 positive axonal pathology existed independent of SNTF and APP. These data demonstrate that multiple pathological axonal phenotypes exist post-TBI and provide insight into a more comprehensive approach to the neuropathological assessment of DAI

Suportes poliméricos à base de quitosana: preparação, caracterização e aplicações biocatalíticas na síntese de ésteres terpênicos

TCC (graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Físicas e Matemáticas. Curso de Química.O uso de enzimas em sínteses e biotransformações, de modo geral, requer que as mesmas estejam imobilizadas em um suporte que permita a sua recuperação e a reutilização ao final de cada processo sintético. As lipases microbianas, por exemplo, são amplamente diversificadas em suas propriedades enzimáticas e especificidade do substrato, o que as tornam muito atrativas para a aplicação industrial. Quando imobilizadas, suas propriedades e estabilidade são aumentadas consideravelmente, além do custo envolvido no processo ser mais reduzido. A partir destas considerações, neste trabalho foram preparados suportes poliméricos à base de quitosana para a imobilização de lipases de duas procedências diferentes, utilizando-se dois diferentes agentes reticulantes, o glutaraldeído e o tripolifosfato de sódio (TPP). Estes sistemas foram caracterizados por técnicas como espectroscopia de infravermelho e microscopia eletrônica de varredura afim de se obter informações acerca do grau de desacetilação da quitosana (81%) e da estrutura física externa e interna das microesferas preparadas. Além disso, os suportes de quitosana/glutaraldeído e de quitosana/TPP foram utilizados na síntese de ésteres de aroma derivados dos álcoois terpênicos geraniol e citronelol via reações de transesterificação. As conversões foram maiores ao usar os suportes reticulados com concentrações mais baixas (42%) do que concentrações mais altas (35%) do agente reticulante (glutaraldeído). As reações foram dependentes do tempo e a atividade catalítica da lipase de Burkholderia cepacia (LPS-SD) diminuiu, mantendo-se constante após cinco ciclos reacionais. De modo geral, os suportes preparados mostraram-se eficientes na imobilização de lipases, apresentando importantes aplicações na síntese orgânica

Operating experience of a 50kwth methane chemical looping reactor

Chemical Looping Combustion (CLC) has the potential to efficiently capture CO2 from the combustion of fossil fuels at an affordable price. CLC is a process that produces a flue gas primarily consisting of CO2 and H2O. The CO2 can be easily separated and captured by condensing the H2O, similar to an oxy-fuel process. Although the process looks promising on paper, the challenge is to make chemical looping a reality by demonstrating that the process can work economically. To help achieve this goal, the US Department of Energy’s (DOE) National Energy Technology Laboratory (NETL), has constructed and tested a 50kWth chemical looping reactor (CLR). The general arrangement of the process consists of a bubbling fluidized bed fuel reactor and a fluidized bed/riser air reactor. Three different metal oxide based oxygen carriers have been successfully tested during week-long test campaigns; a hematite ore, promoted hematite ore, and a manufactured copper based oxygen carrier. These three carriers have demonstrated various levels of performance including conversion of natural gas to CO2 and durability. The goal of these tests is to better understand real process metrics so that appropriate economic analysis can be performed

Valores africanos e homofobia de estado em África: A Lei Anti-Homossexualidade do Uganda como estudo de caso

Mestrado em Direitos HumanosA presente dissertação de mestrado tem por objetivo desenvolver uma investigação sobre as minorias sexuais na África, tendo como estudo de caso o Uganda. A análise realizada buscará verificar as reformas legislativas anti homossexualidade realizadas no Uganda nos últimos anos à luz do seu enquadramento histórico, cultural, político e jurídico. Este estudo propõe uma reflexão da homofobia no Uganda, a partir de sua existência, permanência e crescimento, contrariando todos os tratados internacionais de direitos humanos. Tal reflexão será consubstanciada nos últimos anos, desde a aprovação da Lei Anti Homossexualidade de 2014 e a trajetória das sodomy laws no país. Para que tal investigação ocorra e tenha os objetivos alcançados, partiremos da delimitação conceitual de todos os termos utilizados neste estudo, bem como de uma análise da proteção das minorias sexuais nos padrões internacionais de Direitos Humanos. Doravante, o estudo se dedica as minorias sexuais no continente africano, a presença da homofobia em vários países e o argumento das tradições jurídicas africanas sobre o tema. Por fim, examinaremos a homossexualidade e a identidade de género no Uganda, seu contexto histórico desde o período pré-colonial, depois enquanto colônia britânica e por último, o ponto de situação atual dos indivíduos LGBTI no país. Em seu contexto cultural, analisaremos os argumentos utilizados contrários à homossexualidade e a chegada dos missionários norte-americanos no Uganda. No enquadramento político nos debruçaremos sobre o governo do país e o Presidente Yoweri Museveni. No plano jurídico, atentaremos para as previsões constitucionais que protegem o principio da igualdade e da não discriminação, o Código Penal que prevê a criminalização dos atos sexuais entre pessoas do mesmo sexo, passando pelos instrumentos internacionais de direitos humanos dos quais o Uganda é signatário. Nesta análise, atentaremos em especial ao modo como o legislador e os tribunais ugandenses têm lidado com as minorias sexuais, bem como os desafios práticos que identificarmos a partir da opinião de doutrinadores e juristas e perante os organismos internacionais de supervisão e proteção dos direitos humanos.This master's dissertation aims to develop research on sexual minorities in Africa, with a case study about Uganda. The analysis undertaken will seek to verify the anti-homosexuality legislative reforms carried out in Uganda in recent years in light of its historical, cultural, political and legal framework. This study proposes a reflection of homophobia in Uganda from its existence, permanence, and growth, contrary to all international human rights treaties. Such reflection will be substantiated in recent years, since the approval of the Anti Homosexuality Law of 2014 and the trajectory of sodomy laws in the country. For such an investigation to take place and achieve its objectives, we will start from the conceptual delimitation of all terms used in this study, as well as an analysis of the protection of sexual minorities in international human rights standards. Hereafter, the study focuses on sexual minorities on the African continent, the presence of homophobia in various countries and the argument of African legal traditions on the subject. Finally, we will look at homosexuality and gender identity in Uganda, its historical context since the pre-colonial period, then as a British colony, and finally, the current state of affairs of LGBTI individuals in the country. In its cultural context, we will analyze the arguments used against homosexuality and the arrival of US missionaries in Uganda. In the political framework, we will look at the government of the country and President Yoweri Museveni. At the legal level, we will look at the constitutional provisions that protect the principle of equality and non-discrimination, the Criminal Code which provides for the criminalization of same-sex sexual acts, as well as the international human rights instruments to which Uganda is a signatory. In this analysis, we will pay particular attention to the way in which the Ugandan legislature and courts have dealt with sexual minorities, as well as the practical challenges that we identify from the opinion of indoctrinators and jurists and before international human rights oversight and protection bodies