skip to main content


This content will become publicly available on August 9, 2024

Title: Educators’ Perspectives of Using (or Not Using) Online Exam Proctoring
Award ID(s):
2138654
NSF-PAR ID:
10472946
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
USENIX Association
Date Published:
Journal Name:
Proceedings of the 32nd USENIX Security Symposium
Format(s):
Medium: X
Location:
Anaheim, CA
Sponsoring Org:
National Science Foundation
More Like this
  1. Dense, fast-moving regions of ionization called polar cap patches are known to occur in thehigh-latitudeFregion ionosphere. Patches are widely believed to be caused by convection of dense, sunlitplasma into a dark and therefore low-density polar cap ionosphere. This leads to the belief that patches are awinter phenomenon. Surprisingly, a long-term analysis of 3 years of ionospheric measurements from theSwarm satellites shows that large density enhancements occur far more frequently in local summer than localwinter in the Southern Hemisphere (SH). The reverse is true in the Northern Hemisphere (NH). Previouslyreported patch detections in the SH are reexamined. Detection algorithms using only a relative doubling testcount very small densityfluctuations in SH winter due to extremely low ambient densities found there,while much larger enhancements occurring in SH summer are missed due to especially high ambientdensities. The same problem does not afflict results in the NH, where ambient densities are more stableyear-round due to the ionospheric annual asymmetry. Given this new analysis, the definition of a patch as adoubling of the ambient density is not suitable for the SH. We propose a test for patches linked to long-termaveraged solarflux activity, characterized by the 81 day centered meanF10.7index. Importantly, thecurrent patch formation theory is at least incomplete in that it does not predict the observed lack of patchesin SH winter, or the many large enhancements seen in SH summer 
    more » « less
  2. Synthetic rubber produced from nonrenewable fossil fuel requires high energy costs and is dependent on the presumed unstable petroleum price. Natural rubber latex (NRL) is one of the major alternative sustainable rubber sources since it is derived from the plant ‘Hevea brasiliensis’. Our study focuses on integrating sustainably processed carboxycellulose nanofibers from untreated jute biomass into NRL to enhance the mechanical strength of the material for various applications. The carboxycellulose nanofibers (NOCNF) having carboxyl content of 0.94 mmol/g was prepared and integrated into its nonionic form (–COONa) for its higher dispersion in water to increase the interfacial interaction between NRL and NOCNF. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) analyses of NOCNF showed the average dimensions of nanofibers were length (L) = 524 ± 203 nm, diameter (D) 7 ± 2 nm and thickness 2.9 nm. Furthermore, fourier transform infra-red spectrometry (FTIR) analysis of NOCNF depicted the presence of carboxyl group. However, the dynamic light scattering (DLS) measurement of NRL demonstrated an effective diameter in the range of 643 nm with polydispersity of 0.005. Tensile mechanical strengths were tested to observe the enhancement effects at various concentrations of NOCNF in the NRL. Mechanical properties of NRL/NOCNF films were determined by tensile testing, where the results showed an increasing trend of enhancement. With the increasing NOCNF concentration, the film modulus was found to increase quite substantially, but the elongation-to-break ratio decreased drastically. The presence of NOCNF changed the NRL film from elastic to brittle. However, at the NOCNF overlap concentration (0.2 wt. %), the film modulus seemed to be the highest. 
    more » « less
  3. null (Ed.)
    We present a chemo-dynamical study of the Orphan stellar stream using a catalog of RR Lyrae pulsating variable stars for which photometric, astrometric, and spectroscopic data are available. Employing low-resolution spectra from the Sloan Digital Sky Survey (SDSS), we determined line-of-sight velocities for individual exposures and derived the systemic velocities of the RR Lyrae stars. In combination with the stars’ spectroscopic metallicities and Gaia EDR3 astrometry, we investigated the northern part of the Orphan stream. In our probabilistic approach, we found 20 single mode RR Lyrae variables likely associated with the Orphan stream based on their positions, proper motions, and distances. The acquired sample permitted us to expand our search to nonvariable stars in the SDSS dataset, utilizing line-of-sight velocities determined by the SDSS. We found 54 additional nonvariable stars linked to the Orphan stream. The metallicity distribution for the identified red giant branch stars and blue horizontal branch stars is, on average, −2.13 ± 0.05 dex and −1.87 ± 0.14 dex, with dispersions of 0.23 and 0.43 dex, respectively. The metallicity distribution of the RR Lyrae variables peaks at −1.80 ± 0.06 dex and a dispersion of 0.25 dex. Using the collected stellar sample, we investigated a possible link between the ultra-faint dwarf galaxy Grus II and the Orphan stream. Based on their kinematics, we found that both the stream RR Lyrae and Grus II are on a prograde orbit with similar orbital properties, although the large uncertainties on the dynamical properties render an unambiguous claim of connection difficult. At the same time, the chemical analysis strongly weakens the connection between both. We argue that Grus II in combination with the Orphan stream would have to exhibit a strong inverse metallicity gradient, which to date has not been detected in any Local Group system. 
    more » « less