The Khan Academy platform enables powerful on-line courses in which students can watch videos, solve exercises, or earn badges. This platform provides an advanced learning analytics module with useful visualizations. Nevertheless, it can be improved. In this paper, we describe ALAS-KA, which provides an extension of the learning analytics support for the Khan Academy platform. We herein present...

A new measure to enhance the performance of InAs quantum dot solar cell is proposed and measured. One monolayer AlAs is deposited on top of InAs quantum dots (QDs) in multistack solar cells. The devices were fabricated by molecular beam epitaxy. In situ annealing was intended to tune the QD density. A set of four samples were compared: InAs QDs without in situ annealing with and without AlAs ca...

BACKGROUND Colonic involvement in amebic liver abscess (ALA) occurs in more than half of the patients. However no studies have found any association between the site of the colonic lesions and location of abscesses in the liver. Thus, the present study was designed to find the correlation between colonic involvement in solitary and multiple ALAs. METHODS This is a case control study of 80 pat...

We report studies of (GaAs)(n)/(AlAs)(n) ultrashort-period superlattices using synchrotron x-ray scattering. In particular, we demonstrate that interfaces of these superlattices contain features on two different length scales: namely, random atomic mixture and ordered mesoscopic domains. Both features are asymmetric on the two interfaces (AlAs-on-GaAs and GaAs-on-AlAs) for n>2. Periodic composi...

Porphyrias are a group of genetic disorders caused by mutations in enzymes of the heme biosynthesis pathway. Acute attacks of porphyria, reputedly the disease that incapacitated the British sovereign King George III (see this Cell cover), are precipitated by fasting and are treated by infusing heme or glucose, although the underlying molecular mechanisms remain unclear. In this issue of Cell, H...

We study tunneling in semiconductor heterostructures where the constituent materials can have a direct or indirect bandgap. In order to have a good description of the lowest conduction band, we have used the nearest–neighbour sp3s∗ tight–binding model put forward by P. Vogl et al.. A recursive Green– function method yields transmission coefficients from which an expression for the current densi...

A study of electron momentum density distribution in AlAs by means of Compton profiles is presented. The Compton profile measurement on polycrystalline sample of AlAs is performed employing 59.54 keV gamma-rays emanating from Am radioisotope. The measurement is compared with the empirical pseudopotential method (EPM) and there is good agreement between two data. The ionic model calculations for...

Dx centers have been investigated using deep level transient

that his/­her monozygotic twin and a 39% chance that a dizygotic twin will also be dyscalculic. The link also exists between dyscalculics' parents and siblings: around half of the all first-degree family members of a dyscalculic also have dyscalculia (mothers, 67%; fathers, 41%; brothers, 53%; sisters, 52%), and 43% of the second-degree relatives. This prevalence is around tenfold higher than e...