High-Tech Tools for Teaching Physics: the Physics Education Technology Project

This article appeared in the Journal of Online Teaching and Learning September 15, 2006.This paper introduces a new suite of computer simulations from the Physics Education Technology (PhET) project, identifies features of these educational tools, and demonstrates their utility. We compare the use of PhET simulations to the use of more traditional educational resources in lecture, laboratory, recitation and informal settings of introductory college physics. In each case we demonstrate that simulations are as productive, or more productive, for developing student conceptual understanding as real equipment, reading resources, or chalk-talk lectures. We further identify six key characteristic features of these simulations that begin to delineate why these are productive tools. The simulations: support an interactive approach, employ dynamic feedback, follow a constructivist approach, provide a creative workplace, make explicit otherwise inaccessible models or phenomena, and constrain students productively

Variation in mitochondrial DNA and allozymes discriminates early and late forms of chinook salmon (Oncorhynchus tshawytscha) in the Kenai and Kasilof Rivers, Alaska

Genetic differences between early and late forms of Alaskan chinook salmon (Oncorhynchus tshawytscha) were identified using two genetic approaches: mitochondrial DNA (mtDNA) analysis and protein electrophoresis. The study populations consisted of early- and late-run chinook salmon in each of the Kenai and Kasilof rivers in Alaska, and a single population from the Minam River, Oregon, that provided a relative scale for the differences among the Alaskan populations. Two segments of mtDNA were amplified separately using the polymerase chain reaction (PCR) and then digested with 14 to 16 restriction enzymes. Results showed that the two early runs were genetically similar to each other but different from either of the late runs. The late runs were different from each other based on the frequency of the common haplotypes. The Minam River stock shared two haplotypes with the Alaskan stocks and displayed one unique haplotype. The frequency difference in the shared haplotypes together with the presence of a unique haplotype allowed us to separate the Oregon population from those in Alaska. In the protein analysis, each of the five populations was examined at 30 allozyme loci to determine variation within and between the runs. Based on 14 polymorphic loci, Minam River chinook salmon were genetically distinct from the Alaskan populations. Within the Alaskan populations, the two early runs were most similar to each other but different from the two late runs; the two late runs were also genetically most similar to each other. Based on all loci, protein electrophoresis proved to be a useful technique to separate stocks of chinook salmon. On a locus by locus basis, however, mtDNA was more powerful. Both mtDNA and allozyme analysis suggest that chinook salmon may segregate into genetically different early and late forms within a drainage

“We Never Get Stuck:” A Collaborative Analysis of Change and Coastal Community Subsistence Practices in the Northern Bering and Chukchi Seas, Alaska

The Indigenous communities of the northern Bering Sea and Chukchi Sea are experiencing extensive social, economic, and technological change. The region’s marine ecosystem is also characterized by a high degree of variability and by rapid change. Residents of eight coastal communities from Savoonga to Utqiaġvik were involved in the Chukchi Coastal Communities Project, which used the results of a literature review together with the experiences of the community participants to co-analyze what is known about societal and environmental change in the region and what the communities’ experiences have been in responding to those changes. Some of the observed changes are transient in duration and effect, such as the passage of an individual ship, whereas others, such as the creation of the Red Dog Mine Port Site, persist and may force coastal residents to make lasting changes in their activities. Some responses can use existing knowledge (e.g., hunting bowhead whales in fall as well as spring), whereas others may require learning and experimentation (e.g., harvesting new species such as the Hanasaki crab). Our findings show that the results of a change are more important than the source of the change. They also emphasize the continuing importance of traditional values and practices as well as attitudes conducive to persistence and innovation. Indigenous leadership is an essential component of continued resilience as the ecosystem continues to change. The resilient characteristics of coastal communities and their ability to determine their own responses to change need greater attention to match the research effort directed at understanding the ecosystem. Les collectivités autochtones du nord de la mer de Béring et de la mer des Tchouktches font face à d’importants changements sur les plans social, économique et technologique. L’écosystème marin de la région est également caractérisé par un grand degré de variabilité et de changement rapide. Les habitants de huit collectivités côtières, de Savoonga à Utqiaġvik, ont participé au projet des collectivités côtières des Tchouktches. S’appuyant sur l’examen de documentation et sur l’expérience des participants des collectivités, les responsables de ce projet ont co-analysé les faits connus au sujet du changement social et environnemental dans la région de même que l’expérience des collectivités en matière de réponse à ces changements. La durée et l’effet des changements observés sont parfois transitoires, comme le passage d’un navire, tandis que d’autres, comme l’aménagement du site portuaire de la mine de Red Dog, perdurent et risquent de forcer les habitants de la côte à modifier leurs activités en permanence. Certaines des réponses peuvent s’appuyer sur des connaissances déjà acquises (comme le fait de chasser la baleine boréale à l’automne ainsi qu’au printemps), tandis que d’autres pourraient nécessiter de l’apprentissage et de l’expérimentation (comme la récolte d’une nouvelle espèce comme le crabe Hanasaki). Nos constatations démontrent que les résultats d’un changement sont plus importants que la source du changement. Elles mettent également l’accent sur l’importance continuelle des valeurs et des pratiques traditionnelles ainsi que sur les attitudes propices à la persistance et à l’innovation. Le leadership autochtone est une composante essentielle de la résilience continue alors que l’écosystème évolue sans cesse. Les caractéristiques de résilience des collectivités côtières et leur capacité à déterminer leurs propres réponses au changement doivent faire l’objet d’une plus grande attention afin d’être à la hauteur de l’effort de recherche visant à comprendre l’écosystème.&nbsp

Epidemiological considerations in transgender health : a systematic review with focus on higher quality data

Background: High quality data pertaining to the size of the transgender and gender diverse (TGD) population are scant, however, several recently published studies may provide more reliable contemporary estimates.Aims: To summarize the estimated number and proportion of TGD individuals overall and across age groups, based on most accurate data.Methods: This systematic review focused on recent studies (published from 2009 through 2019) that utilized sound methodology in assessing the proportion of TGD people in the general population. Publications were included if they used clear definitions of TGD status, and calculated proportions based on a well-defined sampling frame. Nineteen eligible publications represented two broad categories of studies: those that used data from large health care systems; and those that identified TGD individuals from population surveys.Results: Among health system-based studies, TGD persons were identified using relevant diagnostic codes or clinical notes. The proportions of individuals with a TGD-relevant diagnosis or other recorded evidence ranged between 17 and 33 per 100,000 enrollees. In population surveys TGD status was ascertained based on self-report with either narrow or broad definitions. The survey-based estimates were orders of magnitude higher and consistent across studies using similar definitions. When the surveys specifically inquired about 'transgender' identity, the estimates ranged from 0.3% to 0.5% among adults, and from 1.2% to 2.7% among children and adolescents. When the definition was expanded to include broader manifestations of 'gender diversity', the corresponding proportions increased to 0.5-4.5% among adults and 2.5-8.4% among children and adolescents. Upward temporal trends in the proportion of TGD people were consistently observed.Conclusions: Current data indicate that people who self-identify as TGD represent a sizable and increasing proportion of the general population. This proportion may differ, depending on inclusion criteria, age, and geographic location, but well-conducted studies of similar type and design tend to produce comparable results

Antarctic Water Tracks: Microbial Community Responses to Variation in Soil Moisture, pH, and Salinity

Ice-free soils in the McMurdo Dry Valleys select for taxa able to cope with challenging environmental conditions, including extreme chemical water activity gradients, freeze-thaw cycling, desiccation, and solar radiation regimes. The low biotic complexity of Dry Valley soils makes them well suited to investigate environmental and spatial influences on bacterial community structure. Water tracks are annually wetted habitats in the cold-arid soils of Antarctica that form briefly each summer with moisture sourced from snow melt, ground ice thaw, and atmospheric deposition via deliquescence and vapor flow into brines. Compared to neighboring arid soils, water tracks are highly saline and relatively moist habitats. They represent a considerable area (&sim;5&ndash;10 km2) of the Dry Valley terrestrial ecosystem, an area that is expected to increase with ongoing climate change. The goal of this study was to determine how variation in the environmental conditions of water tracks influences the composition and diversity of microbial communities. We found significant differences in microbial community composition between on- and off-water track samples, and across two distinct locations. Of the tested environmental variables, soil salinity was the best predictor of community composition, with members of the Bacteroidetes phylum being relatively more abundant at higher salinities and the Actinobacteria phylum showing the opposite pattern. There was also a significant, inverse relationship between salinity and bacterial diversity. Our results suggest water track formation significantly alters dry soil microbial communities, likely influencing subsequent ecosystem functioning. We highlight how Dry Valley water tracks could be a useful model system for understanding the potential habitability of transiently wetted environments found on the surface of Mars. &nbsp;</p

Exploring the boundaries of microbial habitability in soil

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Dragone, N. B., Diaz, M. A., Hogg, I., Lyons, W. B., Jackson, W. A., Wall, D. H., Adams, B. J., & Fierer, N. Exploring the boundaries of microbial habitability in soil. Journal of Geophysical Research: Biogeosciences, 126(6), (2021): e2020JG006052, https://doi.org/10.1029/2020JG006052.Microbes are widely assumed to be capable of colonizing even the most challenging terrestrial surface environments on Earth given enough time. We would not expect to find surface soils uninhabited by microbes as soils typically harbor diverse microbial communities and viable microbes have been detected in soils exposed to even the most inhospitable conditions. However, if uninhabited soils do exist, we might expect to find them in Antarctica. We analyzed 204 ice-free soils collected from across a remote valley in the Transantarctic Mountains (84–85°S, 174–177°W) and were able to identify a potential limit of microbial habitability. While most of the soils we tested contained diverse microbial communities, with fungi being particularly ubiquitous, microbes could not be detected in many of the driest, higher elevation soils—results that were confirmed using cultivation-dependent, cultivation-independent, and metabolic assays. While we cannot confirm that this subset of soils is completely sterile and devoid of microbial life, our results suggest that microbial life is severely restricted in the coldest, driest, and saltiest Antarctic soils. Constant exposure to these conditions for thousands of years has limited microbial communities so that their presence and activity is below detectable limits using a variety of standard methods. Such soils are unlikely to be unique to the studied region with this work supporting previous hypotheses that microbial habitability is constrained by near-continuous exposure to cold, dry, and salty conditions, establishing the environmental conditions that limit microbial life in terrestrial surface soils.This work was supported by grants from the U.S. National Science Foundation (ANT 1341629 to B. J. Adams, N. Fierer, W. Berry Lyons, and D. H. Wall and OPP 1637708 to B. J. Adams) with additional support provided to N. B. Dragone from University Colorado Department of Ecology and Evolutionary Biology

Elevational constraints on the composition and genomic attributes of microbial communities in Antarctic soils

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Dragone, N. B., Henley, J. B., Holland-Moritz, H., Diaz, M., Hogg, I. D., Lyons, W. B., Wall, D. H., Adams, B. J., & Fierer, N. Elevational constraints on the composition and genomic attributes of microbial communities in Antarctic soils. Msystems, 7(1), (2022): e01330-21, https://doi.org/10.1128/msystems.01330-21.The inland soils found on the Antarctic continent represent one of the more challenging environments for microbial life on Earth. Nevertheless, Antarctic soils harbor unique bacterial and archaeal (prokaryotic) communities able to cope with extremely cold and dry conditions. These communities are not homogeneous, and the taxonomic composition and functional capabilities (genomic attributes) of these communities across environmental gradients remain largely undetermined. We analyzed the prokaryotic communities in soil samples collected from across the Shackleton Glacier region of Antarctica by coupling quantitative PCR, marker gene amplicon sequencing, and shotgun metagenomic sequencing. We found that elevation was the dominant factor explaining differences in the structures of the soil prokaryotic communities, with the drier and saltier soils found at higher elevations harboring less diverse communities and unique assemblages of cooccurring taxa. The higher-elevation soil communities also had lower maximum potential growth rates (as inferred from metagenome-based estimates of codon usage bias) and an overrepresentation of genes associated with trace gas metabolism. Together, these results highlight the utility of assessing community shifts across pronounced environmental gradients to improve our understanding of the microbial diversity found in Antarctic soils and the strategies used by soil microbes to persist at the limits of habitability.Geospatial support for this work was provided by the Polar Geospatial Center under NSF-OPP awards 1043681 and 155969. This work was supported by grants from the U.S. National Science Foundation Office of Polar Programs (1341629, 1341629, 1341736, and 1637708 to B.J.A., N.F., W.B.L., and D.H.W.), with additional support provided to N.B.D. from the University of Colorado Department of Ecology and Evolutionary Biology

Fluorescent Chemosensors for Toxic Organophosphorus Pesticides: A Review

Many organophosphorus (OP) based compounds are highly toxic and powerful inhibitors of cholinesterases that generate serious environmental and human health concerns. Organothiophosphates with a thiophosphoryl (P=S) functional group constitute a broad class of these widely used pesticides. They are related to the more reactive phosphoryl (P=O) organophosphates, which include very lethal nerve agents and chemical warfare agents, such as, VX, Soman and Sarin. Unfortunately, widespread and frequent commercial use of OP-based compounds in agricultural lands has resulted in their presence as residues in crops, livestock, and poultry products and also led to their migration into aquifers. Thus, the design of new sensors with improved analyte selectivity and sensitivity is of paramount importance in this area. Herein, we review recent advances in the development of fluorescent chemosensors for toxic OP pesticides and related compounds. We also discuss challenges and progress towards the design of future chemosensors with dual modes for signal transduction. © 2010 by the authors; licensee MPDI, Basel, Switzerland

Sustaining The Saco Estuary: Final Report 2015

This study focuses on the Saco estuary, the tidal portion of the Saco River, which drains the largest watershed in southern Maine. With headwaters in the White Mountains of New Hampshire, the watershed encompasses more than 4,400 km2, and provides clean healthy drinking water to over 100,000 people living and working in communities in southern Maine. When the study began in 2009, very little was known about the ecology of the Saco estuary. Researchers at the University of New England and the Wells National Estuarine Research Reserve employed the process of collaborative learning to bring together people who care about the estuary in order to identify their concerns. A Stewardship Network composed of people employed by municipal, state and federal governments, water supply organizations and businesses, volunteers from municipal boards making land use decisions, land trusts, property owners and representatives from other organizations that are uniquely focused on the region was formed. The Stewardship Network helped to define the project goals and objectives, and provided input and guidance over the five-year project. This report explains what the researchers discovered about the ecology of the estuary, along with what they learned about its social and economic components. This baseline assessment contributes to the long-term goal of restoring and sustaining the structure and function of the estuary, and supports the efforts of government, businesses and local organizations that value the estuary and depend upon the natural services it provides