1,102 research outputs found
Creating E-Textile Activities in a Textile Design Course to Engage Female Middle School Students in STEM Learning: An Undergraduate Design Experience
Widespread agreement exists that the United States faces a serious challenge in the areas of science, technology, engineering, and mathematics (STEM). There is a particular deficit of females (Watt, 2010) and members of underserved groups like rural populations (Smith, Nelson, Trygstad, & Banilower, 2013) who are interested in STEM topics and qualified to pursue STEM careers. Initiatives are needed to encourage more students, especially females and rural students, to go into STEM fields. In this project, e-textile activities were designed by a senior level undergraduate textile design class to engage female middle-school students in STEM learning. E-textile activities have the potential to increase enjoyment of and interest in STEM activities, taking STEM courses, consideration of STEM careers, and confidence in STEM ability
Metastability in Spin-Polarized Fermi Gases
We study the role of particle transport and evaporation on the phase
separation of an ultracold, spin-polarized atomic Fermi gas. We show that the
previously observed deformation of the superfluid paired core is a result of
evaporative depolarization of the superfluid due to a combination of enhanced
evaporation at the center of the trap and the inhibition of spin transport at
the normal-superfluid phase boundary. These factors contribute to a
nonequilibrium jump in the chemical potentials at the phase boundary. Once
formed, the deformed state is highly metastable, persisting for times of up to
2 s.Comment: 4 pages, 6 figure
Shoot growth of woody trees and shrubs is predicted by maximum plant height and associated traits
1. The rate of elongation and thickening of individual branches (shoots) varies across plant species. This variation is important for the outcome of competition and other plant-plant interactions. Here we compared rates of shoot growth across 44 species from tropical, warm temperate, and cool temperate forests of eastern Australia.2. Shoot growth rate was found to correlate with a suite of traits including the potential height of the species, xylem-specific conductivity, leaf size, leaf area per xylem cross-section, twig diameter (at 40 cm length), wood density and modulus of elasticity.3. Within this suite of traits, maximum plant height was the clearest correlate of growth rates, explaining 50 to 67% of the variation in growth overall (p p 4. Growth rates were not strongly correlated with leaf nitrogen or leaf mass per unit leaf area.5. Correlations between growth and maximum height arose both across latitude (47%, p p p p < 0.0001), reflecting intrinsic differences across species and sites
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Detection of the large meteoroid/NEO flux using infrasound: Recent detection of the November 21, 1995 Colorado fireball
During the early morning of November 21, 1995, a fireball as bright as the full moon entered the atmosphere over southeastern Colorado and subsequently produced audible sonic boom reports from Texas to Wyoming. The event was detected locally by a security video camera which showed the reflection of the fireball event on the hood of a truck. The camera also recorded tree shadows cast by the light of the fireball. This recording includes the audio signal of a strong double boom as well. Subsequent investigation of the array near Los Alamos, New Mexico operated by the Los Alamos National Laboratory as part of its commitment to the Comprehensive Test Ban Treaty negotiations, showed the presence of an infrasonic signal from the proper direction at about the correct time for this fireball. The Los Alamos array is a four-element infrasonic array in near-continuous operation on the Laboratory property. The preliminary characteristics of the signal include the signal onset arrival time of 0939:20 UT (0239:20 MST), with a maximum timing uncertainty of {+-} 2 minutes, the signal onset time delay from the appearance of the fireball of 19 minutes, 20 seconds, the total signal duration of 2 minutes 10 seconds, the source location toward 31 degrees from true north, the horizontal trace velocity of 429 m/sec, the signal velocity of 0.30 {+-} 0.03 km/sec, assuming a 400 km horizontal range to the fireball, the dominant signal frequency content of 0.25 to 0.84 Hz (analyzed in the frequency interval from 0.2 to 2.0 Hz), the maximum signal cross-correlation of 0.97 and the maximum signal amplitude of 2.0 {+-} 0.1 microbars. Also, on the basis of the signal period at maximum amplitude, we estimate a source energy for this event of between 10 to 100 tons of TNT (53.0 tons nominal)
Global production and free access to Landsat-scale Evapotranspiration with EEFlux and eeMETRIC
EEFlux (Earth Engine Evapotranspiration Flux) is a version of the METRIC (mapping evapotranspiration at high resolution with internal calibration) application that operates on the Google Earth Engine (EE). EEFlux has a web-based interface and provides free public access to transform Landsat images into 30 m spatial evapotranspiration (ET) data for terrestrial land areas around the globe. EE holds the entire Landsat archive to power EEFlux along with NLDAS/CFSV2 gridded weather data for estimating reference ET. EEFlux is a part of the upcoming OpenET platform (https://openetdata.org/ ) that has leveraged nonprofit funding to provide ET information to all of the lower 48 states for free, as a means to foster water exchange between agriculture, cities and environment (Melton et al., 2020). The METRIC version in OpenET is named eeMETRIC, and includes cloud detection and time integration of ET snapshots into monthly ET estimates. EEFlux and eeMETRIC employ METRIC’s “mountain” algorithms for estimating aerodynamics and solar radiation in complex terrain. Calibration is automated and ET images are computed for download in seconds using EE’s large computational capacity
Evidence of strong stabilizing effects on the evolution of boreoeutherian (Mammalia) dental proportions.
The dentition is an extremely important organ in mammals with variation in timing and sequence of eruption, crown morphology, and tooth size enabling a range of behavioral, dietary, and functional adaptations across the class. Within this suite of variable mammalian dental phenotypes, relative sizes of teeth reflect variation in the underlying genetic and developmental mechanisms. Two ratios of postcanine tooth lengths capture the relative size of premolars to molars (premolar-molar module, PMM), and among the three molars (molar module component, MMC), and are known to be heritable, independent of body size, and to vary significantly across primates. Here, we explore how these dental traits vary across mammals more broadly, focusing on terrestrial taxa in the clade of Boreoeutheria (Euarchontoglires and Laurasiatheria). We measured the postcanine teeth of N = 1,523 boreoeutherian mammals spanning six orders, 14 families, 36 genera, and 49 species to test hypotheses about associations between dental proportions and phylogenetic relatedness, diet, and life history in mammals. Boreoeutherian postcanine dental proportions sampled in this study carry conserved phylogenetic signal and are not associated with variation in diet. The incorporation of paleontological data provides further evidence that dental proportions may be slower to change than is dietary specialization. These results have implications for our understanding of dental variation and dietary adaptation in mammals
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Infrasound from the El Paso super-bolide of October 9, 1997
During the noon hour on October 9, 1997 an extremely bright fireball ({approx}-21.5 in stellar magnitude putting it into the class of a super-bolide) was observed over western Texas with visual sightings from as far away as Arizona to northern Mexico and even in northern New Mexico over 300 miles away. This event produced tremendously loud sonic boom reports in the El Paso area. It was also detected locally by 4 seismometers which are part of a network of 5 seismic stations operated by the University of Texas at El Paso (UTEP). Subsequent investigations of the data from the six infrasound arrays used by LANL (Los Alamos National Laboratory) and operated for the DOE (Department of Energy) as a part of the CTB (Comprehensive Test Ban) Research and Development program for the IMS (International Monitoring System) showed the presence of an infrasonic signal from the proper direction at the correct time for this super-bolide from two of the six arrays. Both the seismic and infrasound recordings indicated that an explosion occurred in the atmosphere at source heights from 28--30 km, having its epicenter slightly to the northeast of Horizon City, Texas. The signal characteristics, analyzed from {approx}0.1 to 5.0 Hz, include a total duration of {approx}4 min (at Los Alamos, LA) to >{approx}5 min at Lajitas, Texas, TXAR, another CTB IMS array operated by E. Herrin at Southern Methodist University (SMU) for a source directed from LA toward {approx}171--180 deg and from TXAR of {approx}321-4 deg respectively from true north. The observed signal trace velocities (for the part of the recording with the highest cross-correlation) at LA ranged from 300--360 m/sec with a signal velocity of 0.30 {+-} 0.03 km/sec, implying a Stratospheric (S Type) ducted path. The dominant signal frequency at LA was from 0.20 to 0.80 Hz, with a peak near 0.3 Hz. These highly correlated signals at LA had a very large, peak to peak, maximum amplitude of 21.0 microbars (2.1 Pa). The analysis, using several methods that incorporate various observed signal characteristics, total distance traveled, etc., indicates that the super-bolide probably had a source energy in the range between 10--100 tons (TNT equivalent). This is somewhat smaller than the source energy estimate made using US DoD satellite data (USAF news release, June 8, 1998)
Moderated Network Models
Pairwise network models such as the Gaussian Graphical Model (GGM) are a
powerful and intuitive way to analyze dependencies in multivariate data. A key
assumption of the GGM is that each pairwise interaction is independent of the
values of all other variables. However, in psychological research this is often
implausible. In this paper, we extend the GGM by allowing each pairwise
interaction between two variables to be moderated by (a subset of) all other
variables in the model, and thereby introduce a Moderated Network Model (MNM).
We show how to construct the MNM and propose an L1-regularized nodewise
regression approach to estimate it. We provide performance results in a
simulation study and show that MNMs outperform the split-sample based methods
Network Comparison Test (NCT) and Fused Graphical Lasso (FGL) in detecting
moderation effects. Finally, we provide a fully reproducible tutorial on how to
estimate MNMs with the R-package mgm and discuss possible issues with model
misspecification
Coordination of Mobile Mules via Facility Location Strategies
In this paper, we study the problem of wireless sensor network (WSN)
maintenance using mobile entities called mules. The mules are deployed in the
area of the WSN in such a way that would minimize the time it takes them to
reach a failed sensor and fix it. The mules must constantly optimize their
collective deployment to account for occupied mules. The objective is to define
the optimal deployment and task allocation strategy for the mules, so that the
sensors' downtime and the mules' traveling distance are minimized. Our
solutions are inspired by research in the field of computational geometry and
the design of our algorithms is based on state of the art approximation
algorithms for the classical problem of facility location. Our empirical
results demonstrate how cooperation enhances the team's performance, and
indicate that a combination of k-Median based deployment with closest-available
task allocation provides the best results in terms of minimizing the sensors'
downtime but is inefficient in terms of the mules' travel distance. A
k-Centroid based deployment produces good results in both criteria.Comment: 12 pages, 6 figures, conferenc
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