972 research outputs found
Disruption of the developmental programme of Trypanosoma brucei by genetic ablation of TbZFP1, a differentiation-enriched CCCH protein
No full textThe regulation of differentiation is particularly important in microbial eukaryotes that inhabit multiple environments. The parasite Trypanosoma brucei is an extreme example of this, requiring exquisite gene regulation during transmission from mammals to the tsetse fly vector. Unusually, trypanosomes rely almost exclusively on post-transcriptional mechanisms for regulated gene expression. Hence, RNA binding proteins are potentially of great significance in controlling stage-regulated processes. We have previously identified TbZFP1 as a trypanosome molecule transiently enriched during differentiation to tsetse midgut procyclic forms. This small protein (101 amino acids) contains the unusual CCCH zinc finger, an RNA binding motif. Here, we show that genetic ablation of TbZFP1 compromises repositioning of the mitochondrial genome, a specific event in the strictly regulated differentiation programme. Despite this, other events that occur both before and after this remain intact. Significantly, this phenotype correlates with the TbZFP1 expression profile during differentiation. This is the first genetic disruption of a developmental regulator in T. brucei. It demonstrates that programmed events in parasite development can be uncoupled at the molecular level. It also further supports the importance of CCCH proteins in key aspects of trypanosome cell function
Revisiting and Refining Relations Between Nonsymbolic Ratio Processing and Symbolic Math Achievement
No full textIn their 2016 Psych Science article, Matthews, Lewis and Hubbard (2016, https://doi.org/10.1177/0956797615617799) leveled a challenge against the prevailing theory that fractions—as opposed to whole numbers—are incompatible with humans’ primitive nonsymbolic number sense. Their ratio processing system (RPS) account holds that humans possess a primitive system that confers the ability to process nonysmbolic ratio magnitudes. Perhaps the most striking finding from Matthews et al. was that ratio processing ability predicted symbolic fractions knowledge and algebraic competence. The purpose of the current study was to replicate Matthews et al.’s novel results and to extend the study by including a control measure of fluid intelligence and an additional nonsymbolic magnitude format as predictors of multiple symbolic math outcomes. Ninety-nine college students completed three comparison tasks deciding which of two nonsymbolic ratios was numerically larger along with three simple magnitude comparison tasks in corresponding formats that served as controls. The formats included were lines, circles, and dots. We found that RPS acuity predicted fractions knowledge for three university math placement exam subtests when controlling for simple magnitude acuities and inhibitory control. However, this predictive power of the RPS measure appeared to stem primarily from acuity of the line-ratio format, and that predictive power was attenuated with the inclusion of fluid intelligence. These findings may help refine theories positing the RPS as a domain-specific foundation for building fractional knowledge and related higher mathematics
Revisiting and Refining Relations between Nonsymbolic Ratio Processing and Symbolic Math Achievement
No full textReplicating and expanding Matthews, Lewis, & Hubbard (2016)'s results
Supplementary materials to: Revisiting and refining relations between nonsymbolic ratio processing and symbolic math achievement
No full textSupplementary materials to: Park, Y., & Matthews, P. G. (2021). Revisiting and refining relations between nonsymbolic ratio processing and symbolic math achievement. Journal of Numerical Cognition, 7(3), 328-350. https://doi.org/10.5964/jnc.6927The Supplementary Materials contain the following additional information:
1. Analysis of the relations between ratio acuities measured by Weber fractions (ws) and math abilities.
2. Bivariate correlation tables relating performance among various comparison tasks and math tasks, as well as inhibitory control.
Separate tables were constructed, alternatively using accuracy and ws as the performance metric. Tables were also constructed
with and without the use of listwise deletion.
3. Results from the hierarchical regression analyses predicting math abilities from ws.
4. Results from the hierarchical regression analyses predicting symbolic fraction comparison without including Ravens as a
covariate
James Matthews: 'black voices shout!'
No full textSouth African journalist, poet, author and publisher James Matthews was an outspoken critic of apartheid, and a proponent of a form of black pride based more on the Black Panthers than the Black Consciousness Movement. His writings were widely used by various individuals and organisations to further their aims, but he was never a 'joiner'. He supported movements and allowed them to use his work, but he always remained fiercely independent, so that he would never be required to 'toe the party line'.
Multiple cross-format discriminations across nonsymbolic ratios and symbolic fractions
No full textPrevious studies have demonstrated that humans can represent fractional magnitudes abstractly and amodally (e.g., Balci & Gallistel, 2006; Bonn & Cantlon, 2017; Jacob et al., 2012). One line of studies has supported this by showing that humans can compare across fractions and nonsymbolic ratios accurately and rapidly (e.g., Matthews & Chesney, 2015; Kalra et al., 2020). In these cross-format comparisons, individuals have sometimes shown whereby they overestimate the sizes of nonsymbolic ratios relative to symbolic ones.
We aim to replicate and expand these previous findings by conducting a series of cross-format comparison tasks comparing across different nonsymbolic ratios, across nonsymbolic and symbolic fractions and across nonsymbolic ratio and decimals. The nonsymbolic ratios will be instantiated by lines, circles, blobs and dots (Park et al., 2020).
1. Do the findings the adults can successfully compare across different nonsymbolic ratios and across nonsymbolic and symbolic fractions replicate?
2. Will all comparisons (between and within format) show distance effects?
4. In the cross-format comparisons between nonsymbolic ratio and symbolic fractions, is the bias toward overestimating nonsymbolic ratios similar across formats?
5. In the cross-format comparisons between nonsymbolic ratio and decimals, is there also a bias toward overestimation in nonsymbolic format?
Experiment 1 will conduct a series of nonsymbolic ratio cross-format comparisons with various formats. Experiment 2 will test a series of cross-format comparisons across various nonsymbolic ratios and symbolic fractions. Lastly, Experiment 3 will test a series of cross-format comparisons cross various nonsymbolic ratios and symbolic decimals
Understanding emotions in cognitive processes: the concept of G. Matthews
No full textКомплексний підхід дослідження Дж. Метьюза розглядає сучасний спосіб вивчення емоцій у сфері когнітивної психології. Освітлюються передові новації та висновки одразу різних галузей дослідження емоцій у пізнанні. Стаття розглядає новітні підходи до розгляду природи емоційних станів та їхнього взаємозв’язку з такими складовими як: характер, темперамент, пізнання, особистість та вплив процесу вибору на формування емоцій. Увага зосереджується на аналізі двох підходів, зазначених Дж. Метьюзом – нейрозбудження та дизайну, ілюструючи сучасний стан проблематики як структурно-функціональний.The comprehensive research approach of J. Matthews examines the modern way of studying emotions in the field of cognitive psychology. The advance innovations and conclusions of different fields of research of emotions in cognition are highlighted. The article illuminates the latest approaches to considering the nature of emotional states and their relationship with such components as: character, temperament, cognition, personality and the influence of the choice process on the formation of emotions. Attention is focused on the analysis of two approaches indicated by J. Matthews – the arousal and design theory, illustrating the current state of the problem as structural and functional. From the point of view of philosophical analysis, modern problematic can be constructed as a structuralfunctional system of interrelationships and contradictions. Comparing the approaches allows us to consider their functional and structural differences. Such a representation of the current state of research on emotions in cognition reveals a much deeper analysis and comparison of different approaches and concepts with the aim of further theoretical development of this direction in science. The author reveals the general problem of emotions as a system of relations between functions in a holistic system
"We have not learned how to wage war there": the Soviet approach in Afghanistan 1979-1989.
No full textForward by Dr. William G. Robertson: The Combat Studies Institute (CSI) is pleased to present its latest publication in the Occasional Paper Series, "We Have Not Learned How to Wage War There" The Soviet Approach in Afghanistan,1979-1989, by Mr. Matt Matthews. For this work, Mr. Matthews collected a wide variety of sources on the subject, many of them of primary accounts, and used these materials to provide an overview of the evolution of the Soviet operational approach in Afghanistan between 1979 and 1989. This Soviet experience offers a number of useful insights for American military professionals who are, as of this writing, conducting operations in Afghanistan. Mr. Matthews begins his study by examining the Soviets' planning for its invasion of Afghanistan and initial goals for that campaign. The author then looks closely at how the Soviets adapted their tactics and organization to meet the committed and resilient insurgent threat that emerged to do battle against Soviet forces. Despite conventional interpretations of this campaign in Afghanistan which emphasize the rigidity of Soviet methods, Matthews' study suggests that the Soviets were flexible in their overall approach. The Soviet government did, for example, launch nation-building initiatives that would look familiar to American military officers who served in Afghanistan in the first decade of the 21st century. These efforts, however, were seriously hindered by a Soviet military culture that opposed a more comprehensive campaign to foster a popular central Afghan government. Matthews concludes his study by examining Soviet operations to extract their forces from Afghanistan while nonetheless leaving a viable, if not popular, Afghan government in place
The developmental cell biology of Trypanosoma brucei
No full textTrypanosoma brucei provides an excellent system for studies of many aspects of cell biology, including cell structure and morphology, organelle positioning, cell division and protein trafficking. However, the trypanosome has a complex life cycle in which it must adapt either to the mammalian bloodstream or to different compartments within the tsetse fly. These differentiation events require stage-specific changes to basic cell biological processes and reflect responses to environmental stimuli and programmed differentiation events that must occur within a single cell. The organization of cell structure is fundamental to the trypanosome throughout its life cycle. Modulations of the overall cell morphology and positioning of the specialized mitochondrial genome, flagellum and associated basal body provide the classical descriptions of the different life cycle stages of the parasite. The dependency relationships that govern these morphological changes are now beginning to be understood and their molecular basis identified. The overall picture emerging is of a highly organized cell in which the rules established for cell division and morphogenesis in organisms such as yeast and mammalian cells do not necessarily apply. Therefore, understanding the developmental cell biology of the African trypanosome is providing insight into both fundamentally conserved and fundamentally different aspects of the organization of the eukaryotic cell
Cytochrome oxidase subunit VI of Trypanosoma brucei is imported without a cleaved presequence and is developmentally regulated at both RNA and protein levels
No full textMitochondrial respiration in the African trypanosome undergoes dramatic developmental stage regulation. This requires co-ordinated control of components encoded by both the nuclear genome and the kinetoplast, the unusual mitochondrial genome of these parasites. As a model for understanding the co-ordination of these genomes, we have examined the regulation and mitochondrial import of a nuclear-encoded component of the cytochrome oxidase complex, cytochrome oxidase subunit VI (COXVI). By generating transgenic trypanosomes expressing intact or mutant forms of this protein, we demonstrate that COXVI is not imported using a conventional cleaved presequence and show that sequences at the N-terminus of the protein are necessary for correct mitochondrial sorting. Analyses of endogenous and transgenic COXVI mRNA and protein expression in parasites undergoing developmental stage differentiation demonstrates a temporal order of control involving regulation in the abundance of, first, mRNA and then protein. This represents the first dissection of the regulation and import of a nuclear-encoded protein into the cytochrome oxidase complex in these organisms, which were among the earliest eukaryotes to possess a mitochondrion
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