skip to main content

Search for: All records

Creators/Authors contains: "Khan, I."

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. Free, publicly-accessible full text available September 1, 2022
  2. Students' academic learning, performance, and motivation are ongoing topics in engineering education. Those studies that have attempted to understand the mechanisms of motivation in authentic classroom settings and scenarios are few and limited to the methods used (e.g., self-reports, observations). This Work-in-Progress study explores the utility of electrodermal activity (EDA) and temperature sensors in accurately informing scholars about student performance during an exam in real-time. Correlations between each factor were analyzed. Initial results suggest that peripheral skin temperature has a weak, positive but significant correlation to exam question difficulty r=0.08; p<; 0.001). Also, electrodermal activity and temperature showed a weak,more »positive, but significant correlation (r=0.13; p<; 0.0010.05). The electrodermal activity showed a weak, positive, but significant correlation to exam question difficulty (r=0.16; p<; 0.0010.01). Also, skin temperature correlations with difficulty index (did not) changed across semesters (r=0.18; p<; 0.0010.001). We also developed a multiple regression model and found moderately significant relationships between EDA, difficulty index, and skin temperature (r=0.45; p<; 0.0010.05). The findings suggest that performance is tied to physiological responses among students during exam taking, indicating a possible connection between emotions and cognition via physiology.« less
  3. A bio-orthogonal chemistry-based approach for fluorescent labelling of ribosomal RNA is described. It involves an adenosine analogue modified with trans -cyclooctene and masked 5′-phosphate group using aryl phosphoramidate. The incorporation into rRNA has been confirmed using agarose gel electrophoresis, as well as a highly sensitive UHPLC-MS/MS method. Fluorescent labelling of rRNA has been achieved in live HeLa cells via an inverse electron demand Diels–Alder reaction with a tetrazine conjugated to an Oregon Green fluorophore. This communication describes the stepwise approach that led to the development and characterization of the probe. The results demonstrate a new strategy towards development of futuremore »fluorescent probes to investigate the biochemistry of nucleic acids.« less
  4. Abstract We search for signatures of gravitational lensing in the gravitational-wave signals from compact binary coalescences detected by Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) and Advanced Virgo during O3a, the first half of their third observing run. We study: (1) the expected rate of lensing at current detector sensitivity and the implications of a non-observation of strong lensing or a stochastic gravitational-wave background on the merger-rate density at high redshift; (2) how the interpretation of individual high-mass events would change if they were found to be lensed; (3) the possibility of multiple images due to strong lensing by galaxies ormore »galaxy clusters; and (4) possible wave-optics effects due to point-mass microlenses. Several pairs of signals in the multiple-image analysis show similar parameters and, in this sense, are nominally consistent with the strong lensing hypothesis. However, taking into account population priors, selection effects, and the prior odds against lensing, these events do not provide sufficient evidence for lensing. Overall, we find no compelling evidence for lensing in the observed gravitational-wave signals from any of these analyses.« less
    Free, publicly-accessible full text available December 1, 2022
  5. Abstract We present a search for continuous gravitational-wave emission due to r-modes in the pulsar PSR J0537–6910 using data from the LIGO–Virgo Collaboration observing run O3. PSR J0537–6910 is a young energetic X-ray pulsar and is the most frequent glitcher known. The inter-glitch braking index of the pulsar suggests that gravitational-wave emission due to r-mode oscillations may play an important role in the spin evolution of this pulsar. Theoretical models confirm this possibility and predict emission at a level that can be probed by ground-based detectors. In order to explore this scenario, we search for r-mode emission in the epochsmore »between glitches by using a contemporaneous timing ephemeris obtained from NICER data. We do not detect any signals in the theoretically expected band of 86–97 Hz, and report upper limits on the amplitude of the gravitational waves. Our results improve on previous amplitude upper limits from r-modes in J0537-6910 by a factor of up to 3 and place stringent constraints on theoretical models for r-mode-driven spin-down in PSR J0537–6910, especially for higher frequencies at which our results reach below the spin-down limit defined by energy conservation.« less
    Free, publicly-accessible full text available November 1, 2022
  6. Free, publicly-accessible full text available November 1, 2022
  7. Free, publicly-accessible full text available October 1, 2022
  8. null (Ed.)
  9. null (Ed.)
  10. null (Ed.)