Assessing the impact of using instant messaging in eLearning on the performance of teaching and learning in higher education

There are growing interests in improving teaching and learning performance through eLearning using specific emerging technologies in higher education. As a result, understanding the impact of using such technologies on the performance of teaching and learning is becoming important. This experimental study investigates the impact of eLearning using instant messaging on the performance of teaching and learning in higher education in developing countries. Pre-test and post-test surveys are used for collecting experimental data from participants to investigate the impact of using instant messaging on teaching and learning. Data analysis conducted quantitatively using SPSS reveals that eLearning using instant messaging improves teaching and learning. In particular, the use of instant messaging in eLearning is more effective than face-to-face teaching and learning with respect to the overall performance in the classroom. This leads to the conclusion that eLearning using instant messaging could transform teaching and learning in higher education in developing countries

Formation of new stellar populations from gas accreted by massive young star clusters

Stars in star clusters are thought to form in a single burst from a common progenitor cloud of molecular gas. However, massive, old globular clusters -- with ages greater than 10 billion years and masses of several hundred thousand solar masses -- often harbour multiple stellar populations, indicating that more than one star-forming event occurred during their lifetimes. Colliding stellar winds from late-stage, asymptotic-giant-branch stars are often invoked as second-generation star-formation trigger. The initial cluster masses should be at least 10 times more massive than they are today for this to work. However, large populations of clusters with masses greater than a few million solar masses are not found in the local Universe. Here we report on three 1-2 billion-year-old, massive star clusters in the Magellanic Clouds, which show clear evidence of burst-like star formation that occurred a few hundred million years after their initial formation era. We show that such clusters could accrete sufficient gas reservoirs to form new stars if the clusters orbited in their host galaxies' gaseous discs throughout the period between their initial formation and the more recent bursts of star formation. This may eventually give rise to the ubiquitous multiple stellar populations in globular clusters.Comment: 10 pages, 11 figures, Authors' version of a letter published in Nature (27 January 2016), including Methods and Extended Dat

Balanced Filtering via Non-Disclosive Proxies

We study the problem of non-disclosively collecting a sample of data that is balanced with respect to sensitive groups when group membership is unavailable or prohibited from use at collection time. Specifically, our collection mechanism does not reveal significantly more about group membership of any individual sample than can be ascertained from base rates alone. To do this, we adopt a fairness pipeline perspective, in which a learner can use a small set of labeled data to train a proxy function that can later be used for this filtering task. We then associate the range of the proxy function with sampling probabilities; given a new candidate, we classify it using our proxy function, and then select it for our sample with probability proportional to the sampling probability corresponding to its proxy classification. Importantly, we require that the proxy classification itself not reveal significant information about the sensitive group membership of any individual sample (i.e., it should be sufficiently non-disclosive). We show that under modest algorithmic assumptions, we find such a proxy in a sample- and oracle-efficient manner. Finally, we experimentally evaluate our algorithm and analyze generalization properties

Thermospheric winds around the cusp region

An equatorward wind has been observed first by the balloon‐borne Fabry‐Perot interferometer called High‐Altitude Interferometer Wind Observation on the equatorward side of the cusp near the local noon, which is opposite to the typical direction of neutral wind driven by the day‐night pressure gradient. However, this dayside equatorward wind was not reproduced by the standard Thermosphere Ionosphere Electrodynamics General Circulation Model under the resolution of 5° longitude by 5° latitude (5°×5°). In this study, the Global Ionosphere Thermosphere Model has been run in different cases and under different resolutions to investigate the neutral dynamics around the cusp region. First, we compare the simulations with and without additional cusp energy inputs to identify the influence of cusp heating. Both runs have a resolution of 5°×1° (longitude × latitude) in order to better resolve the cusp region. After adding in the cusp energy, the meridional wind in simulation turns to be equatorward on the dayside, which is consistent with the observation. It indicates that strong heating in the cusp region causes changes in the pressure gradient around the cusp and subsequent variations in the neutral winds. The simulations with the same cusp heating specifications are repeated, but with different horizontal resolutions to examine the influence of resolution on the simulation results. The comparisons show that the resolution of 5°×1° can resolve the cusp region much more stably and consistently than the 5°×5° resolution.Key PointsThe observed equatorward winds around the cusp have been reproduced by GITMThe impact of cusp energy on the horizontal neutral winds has been studiedThe influence of resolution on cusp simulation has also been investigatedPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110850/1/jgra51569.pd

Assessment of the non‐hydrostatic effect on the upper atmosphere using a general circulation model (GCM)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94914/1/grl24025.pd

Effect of the altitudinal variation of the gravitational acceleration on the thermosphere simulation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95479/1/jgra19341.pd

Impact of the altitudinal Joule heating distribution on the thermosphere

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95601/1/jgra20978.pd