The bloodstream differentiation - division of Trypanosoma brucei studied using mitochondrial markers

In the bloodstream of its mammalian host, the African trypanosome Trypanosoma brucei undergoes a life cycle stage differentiation from a long, slender form to a short, stumpy form. This involves three known major events: exit from a proliferative cell cycle, morphological change and mitochondrial biogenesis. Previously, models have been proposed accounting for these events (Matthews & Gull 1994a). Refinement of, and discrimination between, these models has been hindered by a lack of stage-regulated antigens useful as markers at the single-cell level. We have now evaluated a variety of cytological markers and applied them to investigate the coordination of phenotypic differentiation and cell cycle arrest. Our studies have focused on the differential expression of the mitochondrial enzyme dihydrolipoamide dehydrogenase relative to the differentiation-division of bloodstream trypanosomes. The results implicate a temporal order of events: commitment, division, phenotypic differentiation

The North Atlantic subpolar gyre regulates the spawning distribution of blue whiting (Micromesistius poutassou Risso)

The spawning stock of blue whiting (Micromesistius poutassou), an economically important pelagic gadoid in the North Atlantic Ocean, increased threefold after 1995. The reproductive success of the stock is largely determined during the very early stages of life, but little is known about the spawning dynamics of this species. Here we show that the spawning distribution of blue whiting is variable, regulated by the hydrography west of the British Isles. When the North Atlantic subpolar gyre is strong and spreads its cold, fresh water masses east over Rockall Plateau, the spawning is constrained along the European continental slope and in a southerly position near Porcupine Bank. When the gyre is weak and conditions are relatively saline and warm, the spawning distribution moves northwards along the slope and especially westwards covering Rockall Plateau. The apparent link between the spawning distribution and the subpolar gyre is the first step towards understanding the reproduction variability, which currently is the main challenge for appropriate management of the blue whiting stock

Report from the STEM 2026 Workshop on Assessment, Evaluation, and Accreditation

A gathering of science, technology, engineering, and math (STEM) higher education stakeholders met in November 2018 to consider the relationship between innovation in education and assessment. When we talk about assessment in higher education, it is inextricably linked to both evaluation and accreditation, so all three were considered. The first question we asked was can we build a nation of learners? This starts with considering the student, first and foremost. As educators, this is a foundation of our exploration and makes our values transparent. As educators, how do we know we are having an impact? As members and implementers of institutions, programs and professional societies, how do we know students are learning and that what they are learning has value? The focus of this conversation was on undergraduate learning, although we acknowledge that the topic is closely tied to successful primary and secondary learning as well as graduate education. Within the realm of undergraduate education, students can experience four-year institutions and two-year institutions, with many students learning at both at different times. Thirty-seven participants spent two days considering cases of innovation in STEM education, learning about the best practices in assessment, and then discussing the relationship of innovation and assessment at multiple levels within the context of higher education. Six working groups looked at course-level, program-level, and institution-level assessment, as well as cross-disciplinary programs, large-scale policy issues, and the difficult-to-name “non-content/cross-content” group that looked at assessment of transferable skills and attributes like professional skills, scientific thinking, mindset, and identity, all of which are related to post-baccalaureate success. These conversations addressed issues that cut across multiple levels, disciplines, and course topics, or are otherwise seen as tangential or perpendicular to perhaps “required” assessment at institutional, programmatic, or course levels. This report presents the context, recommendations, and “wicked” challenges from the meeting participants and their working groups. Along with the recommendations of workshop participants, these intricate challenges weave a complex web of issues that collectively need to be addressed by our community. They generated a great deal of interest and engagement from workshop participants, and act as a call to continue these conversations and seek answers that will improve STEM education through innovation and improved assessment. This material is based upon work supported by the National Science Foundation under Grant No. DUE-1843775. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation

Report from the STEM 2026 Workshop on Assessment, Evaluation, and Accreditation

A gathering of science, technology, engineering, and math (STEM) higher education stakeholders met in November 2018 to consider the relationship between innovation in education and assessment. When we talk about assessment in higher education, it is inextricably linked to both evaluation and accreditation, so all three were considered. The first question we asked was can we build a nation of learners? This starts with considering the student, first and foremost. As educators, this is a foundation of our exploration and makes our values transparent. As educators, how do we know we are having an impact? As members and implementers of institutions, programs and professional societies, how do we know students are learning and that what they are learning has value? The focus of this conversation was on undergraduate learning, although we acknowledge that the topic is closely tied to successful primary and secondary learning as well as graduate education. Within the realm of undergraduate education, students can experience four-year institutions and two-year institutions, with many students learning at both at different times. Thirty-seven participants spent two days considering cases of innovation in STEM education, learning about the best practices in assessment, and then discussing the relationship of innovation and assessment at multiple levels within the context of higher education. Six working groups looked at course-level, program-level, and institution-level assessment, as well as cross-disciplinary programs, large-scale policy issues, and the difficult-to-name “non-content/cross-content” group that looked at assessment of transferable skills and attributes like professional skills, scientific thinking, mindset, and identity, all of which are related to post-baccalaureate success. These conversations addressed issues that cut across multiple levels, disciplines, and course topics, or are otherwise seen as tangential or perpendicular to perhaps “required” assessment at institutional, programmatic, or course levels. This report presents the context, recommendations, and “wicked” challenges from the meeting participants and their working groups. Along with the recommendations of workshop participants, these intricate challenges weave a complex web of issues that collectively need to be addressed by our community. They generated a great deal of interest and engagement from workshop participants, and act as a call to continue these conversations and seek answers that will improve STEM education through innovation and improved assessment. This material is based upon work supported by the National Science Foundation under Grant No. DUE-1843775. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation

Precautionary Regulation in Europe and the United States: A Quantitative Comparison

Much attention has been addressed to the question of whether Europe or the United States adopts a more precautionary stance to the regulation of potential environmental, health, and safety risks. Some commentators suggest that Europe is more risk-averse and precautionary, whereas the US is seen as more risk-taking and optimistic about the prospects for new technology. Others suggest that the US is more precautionary because its regulatory process is more legalistic and adversarial, while Europe is more lax and corporatist in its regulations. The flip-flop hypothesis claims that the US was more precautionary than Europe in the 1970s and early 1980s, and that Europe has become more precautionary since then. We examine the levels and trends in regulation of environmental, health, and safety risks since 1970. Unlike previous research, which has studied only a small set of prominent cases selected non-randomly, we develop a comprehensive list of almost 3,000 risks and code the relative stringency of regulation in Europe and the US for each of 100 risks randomly selected from that list for each year from 1970 through 2004. Our results suggest that: (a) averaging over risks, there is no significant difference in relative precaution over the period, (b) weakly consistent with the flip-flop hypothesis, there is some evidence of a modest shift toward greater relative precaution of European regulation since about 1990, although (c) there is a diversity of trends across risks, of which the most common is no change in relative precaution (including cases where Europe and the US are equally precautionary and where Europe or the US has been consistently more precautionary). The overall finding is of a mixed and diverse pattern of relative transatlantic precaution over the period

The Reference Ability Neural Network Study: Life-Time Stability of Reference-Ability Neural Networks Derived from Task Maps of Young Adults

Analyses of large test batteries administered to individuals ranging from young to old have consistently yielded a set of latent variables representing reference abilities (RAs) that capture the majority of the variance in age-related cognitive change: Episodic Memory, Fluid Reasoning, Perceptual Processing Speed, and Vocabulary. In a previous paper (Stern et al., 2014), we introduced the Reference Ability Neural Network Study, which administers 12 cognitive neuroimaging tasks (3 for each RA) to healthy adults age 20-80 in order to derive unique neural networks underlying these 4 RAs and investigate how these networks may be affected by aging. We used a multivariate approach, linear indicator regression, to derive a unique covariance pattern or Reference Ability Neural Network (RANN) for each of the 4 RAs. The RANNs were derived from the neural task data of 64 younger adults of age 30 and below. We then prospectively applied the RANNs to fMRI data from the remaining sample of 227 adults of age 31 and above in order to classify each subject-task map into one of the 4 possible reference domains. Overall classification accuracy across subjects in the sample age 31 and above was 0.80+/-0.18. Classification accuracy by RA domain was also good, but variable; memory: 0.72+/-0.32; reasoning: 0.75+/-0.35; speed: 0.79+/-0.31; vocabulary: 0.94+/-0.16. Classification accuracy was not associated with cross-sectional age, suggesting that these networks, and their specificity to the respective reference domain, might remain intact throughout the age range. Higher mean brain volume was correlated with increased overall classification accuracy; better overall performance on the tasks in the scanner was also associated with classification accuracy. For the RANN network scores, we observed for each RANN that a higher score was associated with a higher corresponding classification accuracy for that reference ability. Despite the absence of behavioral performance information in the derivation of these networks, we also observed some brain-behavioral correlations, notably for the fluid-reasoning network whose network score correlated with performance on the memory and fluid-reasoning tasks. While age did not influence the expression of this RANN, the slope of the association between network score and fluid-reasoning performance was negatively associated with higher ages. These results provide support for the hypothesis that a set of specific, age-invariant neural networks underlies these four RAs, and that these networks maintain their cognitive specificity and level of intensity across age. Activation common to all 12 tasks was identified as another activation pattern resulting from a mean-contrast Partial-Least-Squares technique. This common pattern did show associations with age and some subject demographics for some of the reference domains, lending support to the overall conclusion that aspects of neural processing that are specific to any cognitive reference ability stay constant across age, while aspects that are common to all reference abilities differ across age

Early Cortical Thickness Change after Mild Traumatic Brain Injury following Motor Vehicle Collision

In a motor vehicle collision (MVC), survivors often receive mild traumatic brain injuries (mTBI). Although there have been some reports of early white matter changes after an mTBI, much less is known about early cortical structural changes. To investigate early cortical changes within a few days after an MVC, we compared cortical thickness of mTBI survivors with non-mTBI survivors, then reexamined cortical thickness in the same survivors 3 months later. MVC survivors were categorized as mTBI or non-mTBI based on concussive symptoms documented in emergency departments (EDs). Cortical thickness was measured from MRI images using FreeSurfer within a few days and again at 3 months after MVC. Post-traumatic stress symptoms and physical conditions were also assessed. Compared with the non-mTBI group (n=23), the mTBI group (n=21) had thicker cortex in the left rostral middle frontal (rMFG) and right precuneus gyri, but thinner cortex in the left posterior middle temporal gyrus at 7.2±3.1 days after MVC. After 3 months, cortical thickness had decreased in left rMFG in the mTBI group but not in the non-mTBI group. The cortical thickness of the right precuneus region in the initial scans was positively correlated with acute traumatic stress symptoms for all survivors and with the number of reduced activity days for mTBI survivors who completed the follow-up. The preliminary results suggest that alterations in cortical thickness may occur at an early stage of mTBI and that frontal cortex structure may change dynamically over the initial 3 months after mTBI.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140167/1/neu.2014.3492.pd