Anatomy of STEM teaching in North American universities Stains, M; Harshman, J; Barker, M K ...
Science (American Association for the Advancement of Science),
2018-Mar-30, 2018-03-30, 20180330, Letnik:
359, Številka:
6383
Journal Article
Recenzirano
Odprti dostop
Lecture is prominent, but practices vary
A large body of evidence demonstrates that strategies that promote student interactions and cognitively engage students with content (
1
) lead to gains in ...learning and attitudinal outcomes for students in science, technology, engineering, and mathematics (STEM) courses (
1
,
2
). Many educational and governmental bodies have called for and supported adoption of these student-centered strategies throughout the undergraduate STEM curriculum. But to the extent that we have pictures of the STEM undergraduate instructional landscape, it has mostly been provided through self-report surveys of faculty members, within a particular STEM discipline e.g., (
3
–
6
). Such surveys are prone to reliability threats and can underestimate the complexity of classroom environments, and few are implemented nationally to provide valid and reliable data (
7
). Reflecting the limited state of these data, a report from the U.S. National Academies of Sciences, Engineering, and Medicine called for improved data collection to understand the use of evidence-based instructional practices (
8
). We report here a major step toward a characterization of STEM teaching practices in North American universities based on classroom observations from over 2000 classes taught by more than 500 STEM faculty members across 25 institutions.
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The use of exogenous electrical stimulation to promote nerve regeneration has achieved only limited success. Conditions impeding optimized outgrowth may arise from inadequate stimulus ...presentation due to differences in injury geometry or signal attenuation. Implantation of an electrically-conductive biomaterial may mitigate this attenuation and provide a more reproducible signal. In this study, a conductive nanofiller (single-walled carbon nanotubes SWCNT) was selected as one possible material to manipulate the bulk electrical properties of a collagen type I-10% Matrigel™ composite hydrogel. Neurite outgrowth within hydrogels (SWCNT or nanofiller-free controls) was characterized to determine if: (1) nanofillers influence neurite extension and (2) electrical stimulation of the nanofiller composite hydrogel enhances neurite outgrowth. Increased SWCNT loading (10–100-μg/mL) resulted in greater bulk conductivity (up to 1.7-fold) with no significant changes to elastic modulus. Neurite outgrowth increased 3.3-fold in 20-μg/mL SWCNT loaded biomaterials relative to the nanofiller-free control. Electrical stimulation promoted greater outgrowth (2.9-fold) within SWCNT-free control. The concurrent presentation of electrical stimulation and SWCNT-loaded biomaterials resulted in a 7.0-fold increase in outgrowth relative to the unstimulated, nanofiller-free controls. Local glia residing within the DRG likely contribute, in part, to the observed increases in outgrowth; but it is unknown which specific nanofiller properties influence neurite extension. Characterization of neuronal behavior in model systems, such as those described here, will aid the rational development of biomaterials as well as the appropriate delivery of electrical stimuli to support nerve repair.
Novel biomedical devices delivering electrical stimulation are being developed to mitigate symptoms of Parkinson’s, treat drug-resistant depression, control movement or enhance verve regeneration. Carbon nanotubes and other novel materials are being explored for novel nano-neuro devices based on their unique properties. Neuronal growth on carbon nanotubes has been studied in 2D since the early 2000s demonstrating increased outgrowth, synapse formation and network activity. In this work, single-walled carbon nanotubes were selected as one possible electrically-conductive material, dispersed within a 3D hydrogel containing primary neurons; extending previous 2D work to 3D to evaluate outgrowth within nanomaterial composites with electrical stimulation. This is the first study to our knowledge that stimulates neurons in 3D composite nanomaterial-laden hydrogels. Examination of electrically conductive biomaterials may serve to promote regrowth following injury or in long term stimulation.
Earth is heading towards a climate that last existed more than three million years ago (Ma) during the 'mid-Pliocene warm period'
, when atmospheric carbon dioxide concentrations were about 400 parts ...per million, global sea level oscillated in response to orbital forcing
and peak global-mean sea level (GMSL) may have reached about 20 metres above the present-day value
. For sea-level rise of this magnitude, extensive retreat or collapse of the Greenland, West Antarctic and marine-based sectors of the East Antarctic ice sheets is required. Yet the relative amplitude of sea-level variations within glacial-interglacial cycles remains poorly constrained. To address this, we calibrate a theoretical relationship between modern sediment transport by waves and water depth, and then apply the technique to grain size in a continuous 800-metre-thick Pliocene sequence of shallow-marine sediments from Whanganui Basin, New Zealand. Water-depth variations obtained in this way, after corrections for tectonic subsidence, yield cyclic relative sea-level (RSL) variations. Here we show that sea level varied on average by 13 ± 5 metres over glacial-interglacial cycles during the middle-to-late Pliocene (about 3.3-2.5 Ma). The resulting record is independent of the global ice volume proxy
(as derived from the deep-ocean oxygen isotope record) and sea-level cycles are in phase with 20-thousand-year (kyr) periodic changes in insolation over Antarctica, paced by eccentricity-modulated orbital precession
between 3.3 and 2.7 Ma. Thereafter, sea-level fluctuations are paced by the 41-kyr period of cycles in Earth's axial tilt as ice sheets stabilize on Antarctica and intensify in the Northern Hemisphere
. Strictly, we provide the amplitude of RSL change, rather than absolute GMSL change. However, simulations of RSL change based on glacio-isostatic adjustment show that our record approximates eustatic sea level, defined here as GMSL unregistered to the centre of the Earth. Nonetheless, under conservative assumptions, our estimates limit maximum Pliocene sea-level rise to less than 25 metres and provide new constraints on polar ice-volume variability under the climate conditions predicted for this century.
The built environment and social cohesion are increasingly recognized as being associated with older adults' quality of life (QoL). However, limited research in this area still exists and the ...relationship has remained unexplored in the area of Metro Vancouver, Canada. This study examined the association between the built environment and social cohesion with QoL of 160 community-dwelling older adults (aged ≥ 65 years) on low income from Metro Vancouver. Cross-sectional data acquired from the Walk the Talk (WTT) study were used. Health-related QoL (HRQoL) and capability wellbeing were assessed using the EQ-5D-5L and the ICECAP-O, respectively. Measures of the environment comprised the NEWS-A (perceived built environment measure), the Street Smart Walk Score (objective built environment measure), and the SC-5PT (a measure of social cohesion). The primary analysis consists of Tobit regression models to explore the associations between environmental features and HRQoL as well as capability wellbeing. Key findings indicate that after adjusting for covariates, older adults' capability wellbeing was associated with street connectivity and social cohesion, while no statistically significant associations were found between environmental factors and HRQoL. Our results should be considered as hypothesis-generating and need confirmation in a larger longitudinal study.
•Better social cohesion was associated with better capability wellbeing.•Increased street connectivity was associated with lower capability wellbeing.•No statistically significant associations were found for older adults' HRQoL.•Our results should be considered as hypothesis-generating.
To characterize infants affected with perinatal hypoxic ischemic encephalopathy (HIE) who were referred to regional neonatal intensive care units (NICUs) and their related short-term outcomes.
This ...is a descriptive study evaluating the data collected prospectively in the Children's Hospital Neonatal Database, comprised of 27 regional NICUs within their associated children's hospitals. A consecutive sample of 945 referred infants born ⩾36 weeks' gestation with perinatal HIE in the first 3 days of life over approximately 3 years (2010-July 2013) were included. Maternal and infant characteristics are described. Short-term outcomes were evaluated including medical comorbidities, mortality and status of survivors at discharge.
High relative frequencies of maternal predisposing conditions, cesarean and operative vaginal deliveries were observed. Low Apgar scores, profound metabolic acidosis, extensive resuscitation in the delivery room, clinical and electroencephalographic (EEG) seizures, abnormal EEG background and brain imaging directly correlated with the severity of HIE. Therapeutic hypothermia was provided to 85% of infants, 15% of whom were classified as having mild HIE. Electrographic seizures were observed in 26% of the infants. Rates of complications and morbidities were similar to those reported in prior clinical trials and overall mortality was 15%.
Within this large contemporary cohort of newborns with perinatal HIE, the application of therapeutic hypothermia and associated neurodiagnostic studies appear to have expanded relative to reported clinical trials. Although seizure incidence and mortality were lower compared with those reported in the trials, it is unclear whether this represented improved outcomes or therapeutic drift with the treatment of milder disease.
The Antarctic Ice Sheet (AIS) is out of equilibrium with the current anthropogenic‐enhanced climate forcing. Paleoenvironmental records and ice sheet models reveal that the AIS has been tightly ...coupled to the climate system during the past and indicate the potential for accelerated and sustained Antarctic ice mass loss into the future. Modern observations by contrast suggest that the AIS has only just started to respond to climate change in recent decades. The maximum projected sea level contribution from Antarctica to 2100 has increased significantly since the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report, although estimates continue to evolve with new observational and theoretical advances. This review brings together recent literature highlighting the progress made on the known processes and feedbacks that influence the stability of the AIS. Reducing the uncertainty in the magnitude and timing of the future sea level response to AIS change requires a multidisciplinary approach that integrates knowledge of the interactions between the ice sheet, solid Earth, atmosphere, and ocean systems and across time scales of days to millennia. We start by reviewing the processes affecting AIS mass change, from atmospheric and oceanic processes acting on short time scales (days to decades), through to ice processes acting on intermediate time scales (decades to centuries) and the response to solid Earth interactions over longer time scales (decades to millennia). We then review the evidence of AIS changes from the Pliocene to the present and consider the projections of global sea level rise and their consequences. We highlight priority research areas required to improve our understanding of the processes and feedbacks governing AIS change.
Plain Language Summary
The Antarctic Ice Sheet (AIS) is an important component of the global climate system. Human activities have caused the atmosphere and especially the oceans to warm. However, the full effect of human caused climate change on the AIS has not currently been realized because the ice sheet responds on a range of time scales and to many different Earth processes. Modern observations show that West Antarctica has been melting at an accelerating rate since the 2000s, while the data for East Antarctica are less clear. Environmental records preserve the history of the climate and AIS, which extend beyond the instrumental record and reveal how the AIS responded to past climate warming. Estimates of how much the AIS will contribute to sea level rise by the Year 2100 have changed as a result of new information on how the AIS evolved in the past and research into the interactions between the ice sheet, solid Earth atmosphere, and ocean systems. This review brings together our knowledge of the major processes and feedbacks affecting the AIS and the evidence for how the ice sheet changed since the Pliocene. We consider the future estimates and consequences of global sea level rise from melting of the AIS and highlight priority research areas.
Key Points
The AIS is a highly dynamic component of the Earth system, evolving on a broad range of temporal and spatial scales
Paleoenvironmental evidence highlights the centennial to millennial response time scales of the AIS to atmospheric‐ocean forcing
Coupling feedbacks in Earth system components are required to reduce the uncertainty in AIS's contribution to past and future sea level rise
Annual cyanobacterial blooms dominated by Microcystis have occurred in western Lake Erie (U.S./Canada) during summer months since 1995. The production of toxins by bloom-forming cyanobacteria can ...lead to drinking water crises, such as the one experienced by the city of Toledo in August of 2014, when the city was rendered without drinking water for >2 days. It is important to understand the conditions and environmental cues that were driving this specific bloom to provide a scientific framework for management of future bloom events. To this end, samples were collected and metatranscriptomes generated coincident with the collection of environmental metrics for eight sites located in the western basin of Lake Erie, including a station proximal to the water intake for the city of Toledo. These data were used to generate a basin-wide ecophysiological fingerprint of Lake Erie Microcystis populations in August 2014 for comparison to previous bloom communities. Our observations and analyses indicate that, at the time of sample collection, Microcystis populations were under dual nitrogen (N) and phosphorus (P) stress, as genes involved in scavenging of these nutrients were being actively transcribed. Targeted analysis of urea transport and hydrolysis suggests a potentially important role for exogenous urea as a nitrogen source during the 2014 event. Finally, simulation data suggest a wind event caused microcystin-rich water from Maumee Bay to be transported east along the southern shoreline past the Toledo water intake. Coupled with a significant cyanophage infection, these results reveal that a combination of biological and environmental factors led to the disruption of the Toledo water supply. This scenario was not atypical of reoccurring Lake Erie blooms and thus may reoccur in the future.
On the basis of previous ground-based and fly-by information, we knew that Titan's atmosphere was mainly nitrogen, with some methane, but its temperature and pressure profiles were poorly constrained ...because of uncertainties in the detailed composition. The extent of atmospheric electricity ('lightning') was also hitherto unknown. Here we report the temperature and density profiles, as determined by the Huygens Atmospheric Structure Instrument (HASI), from an altitude of 1,400 km down to the surface. In the upper part of the atmosphere, the temperature and density were both higher than expected. There is a lower ionospheric layer between 140 km and 40 km, with electrical conductivity peaking near 60 km. We may also have seen the signature of lightning. At the surface, the temperature was 93.65 +/- 0.25 K, and the pressure was 1,467 +/- 1 hPa.
We present a multi-wavelength study of comet C/2016 R2 (PanSTARRS). This comet was observed on 23 and 24 January 2018 with the IRAM 30 m telescope, and in January to March 2018 with the Nançay radio ...telescope. Visible spectroscopy was performed in December 2017 and February 2018 with small amateur telescopes. We report on measurements of CO, CH3OH, H2CO and HCN production rates, and on the determination of the N2/CO abundance ratio. Several other species, especially OH, were searched for but not detected. The inferred relative abundances, including upper limits for sulfur species, are compared to those measured in other comets at about the same heliocentric distance of ~2.8 AU. The coma composition of comet C/2016 R2 is very different from all other comets observed so far, being rich in N2 and CO and dust poor. This suggests that this comet might belong to a very rare group of comets formed beyond the N2 ice line. Alternatively, comet C/2016 R2 (PanSTARRS) could be the fragment of a large and differentiated transneptunian object, with properties characteristic of volatile-enriched layers.
Objective
There has been interest in a possible negative association between HIV and multiple sclerosis (MS). We aimed to compare the risk of MS in a cohort of individuals living with HIV to that in ...the general population.
Methods
Population‐based health data were accessed for 2 cohorts of HIV‐positive persons from Sweden and British Columbia, Canada. Incident MS was identified using MS registries or a validated algorithm applied to administrative data. Individuals with HIV were followed from 1 year after the first clinical evidence of HIV or the first date of complete administrative health data (Canada = April 1, 1992 and Sweden = January 1, 2001) until the earliest of incident MS, emigration, death, or study end (Canada = March 31, 2020 and Sweden = December 31, 2018). The observed MS incidence rate in the HIV‐positive cohort was compared to the expected age‐, sex‐, calendar year‐, income‐specific, and region of birth‐specific rates in a randomly selected sample of >20% of each general population. The standardized incidence ratio (SIR) for MS following the first antiretroviral therapy exposure (“ART‐exposed”) was also calculated.
Results
The combined Sweden‐Canada cohort included 29,163 (75% men) HIV‐positive persons. During 242,248 person‐years of follow‐up, 14 incident MS cases were observed in the HIV‐positive cohort, whereas 26.19 cases were expected. The SIR for MS in the HIV‐positive population was 0.53 (95% confidence interval CI = 0.32–0.90). The SIR for MS following the first ART exposure was 0.55 (95% CI = 0.31–0.96).
Interpretation
This international population‐based study demonstrated a lower risk of MS among HIV‐positive individuals, and HIV‐positive ART‐exposed individuals. These findings provide support for further exploration into the relationship among HIV, ART, and MS. ANN NEUROL 2024;95:487–494
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