12 research outputs found
Complex adaptive systems and quantitative reasoning in an interdisciplinary STEM mathematics classroom
In this presentation we will share outcomes from the Real STEM project, which provides professional development for rural teachers in the Georgia Coastal Plains supporting implementation of interdisciplinary STEM courses as well as STEM modules in mathematics and science courses. Real STEM includes a number of innovative student-active strategies for teaching including: Understanding by Design (UbD) approaches to teaching for understanding, problem-based learning (PBL), place-based education (PBE), complex adaptive systems (CAS) thinking, and quantitative reasoning (QR). QR is the mathematical underpinning of the projects. The projects are ongoing so we will report our results on impact on teacher practice and student learning to this point. We will conclude with a discussion of how the projects may address issues of engagement for rural, low socio-economic status student populations in STEM in Central America and the Caribbean
Sub-second periodicity in a fast radio burst
Fast radio bursts (FRBs) are millisecond-duration flashes of radio waves that
are visible at distances of billions of light-years. The nature of their
progenitors and their emission mechanism remain open astrophysical questions.
Here we report the detection of the multi-component FRB 20191221A and the
identification of a periodic separation of 216.8(1) ms between its components
with a significance of 6.5 sigmas. The long (~3 s) duration and nine or more
components forming the pulse profile make this source an outlier in the FRB
population. Such short periodicity provides strong evidence for a neutron-star
origin of the event. Moreover, our detection favours emission arising from the
neutron-star magnetosphere, as opposed to emission regions located further away
from the star, as predicted by some models.Comment: Updated to conform to the accepted versio
A Case Study on A University-Community Partnership to Eliminate Racial Disparities in Infant Mortality: Effective Strategies and Lessons Learned
Variation in Rates of Fatal Police Shootings across US States: the Role of Firearm Availability
Development of Immunologic Assays to Measure Response in Horses Vaccinated with Xenogeneic Plasmid DNA Encoding Human Tyrosinase
The First CHIME/FRB Fast Radio Burst Catalog
We present a catalog of 535 fast radio bursts (FRBs) detected by the Canadian
Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) Project
between 400 and 800 MHz from 2018 July 25 to 2019 July 1, including 61 bursts
from 18 previously reported repeating sources. The catalog represents the first
large sample, including bursts from repeaters and non-repeaters, observed in a
single survey with uniform selection effects. This facilitates comparative and
absolute studies of the FRB population. We show that repeaters and apparent
non-repeaters have sky locations and dispersion measures (DMs) that are
consistent with being drawn from the same distribution. However, bursts from
repeating sources differ from apparent non-repeaters in intrinsic temporal
width and spectral bandwidth. Through injection of simulated events into our
detection pipeline, we perform an absolute calibration of selection effects to
account for systematic biases. We find evidence for a population of FRBs -
comprising a large fraction of the overall population - with a scattering time
at 600 MHz in excess of 10 ms, of which only a small fraction are observed by
CHIME/FRB. We infer a power-law index for the cumulative fluence distribution
of ,
consistent with the expectation for a non-evolving population in
Euclidean space. We find is steeper for high-DM events and shallower
for low-DM events, which is what would be expected when DM is correlated with
distance. We infer a sky rate of
above a fluence of 5 Jy ms at 600 MHz, with scattering time at MHz under
10 ms, and DM above 100 pc cm.Comment: 66 pages, 27 figures, 5 tables. Submitted to ApJ