Fabrication of high-entropy nitrides and carbonitrides

In high-entropy alloys, the use of multiple principle alloying elements is known to entropically stabilize the material. Refractory nitrides and carbides of transition metals are widely known for their ultra high-temperature stability and their high hardness, properties that make them valuable materials for extreme environments, such as coating the exterior of hypersonic flight vehicles and the interior of nuclear reactors. By creating entropy-stabilized complex solid solutions of nitrides and carbides, one can take advantage of the inherent favorable properties of these materials, as well as increased thermal stability and solid solution strengthening. Five-metal systems are chosen using first-principles calculations to describe the energetic distribution of possible atomic configurations, in order to identify systems that are likely to form an entropy-stabilized solid solution. Bulk samples of equiatomic, hexanery (5-metal), high-entropy refractory nitrides and carbonitrides were then fabricated to demonstrate this concept, by using a combination of high-energy ball milling, spark plasma sintering, and hot pressing. The uniformity of the microstructures is characterized, and single-phase solid solutions are achieved, thus demonstrating the ability to entropically stabilize multi-component random mixtures of refractory carbides and nitrides. This work is supported by the U.S. Office of Naval Research MURI program (Grant No. N00014-15- 1-2863

Gateveys – An R Toolbox for Re-Traceable Aggregation of Business Tendency Survey Data

This paper describes how to use the R package gateveys to establish a transparent and reproducible aggregation work flow for longitudinal data stemming from business tendency surveys (BTS). Business tendency survey researchers are addressed in particular though the suggested work flow could also be applied to other processes that generate categorical data. The package has two main features: First, it provides functions to build an aggregation process that re-calculates all periods when a new survey wave is added and hence can be fully reproduced at any later stage. Second, the package can be used to dynamically add localized meta information to the resulting time series object during the aggregation process. Besides, the paper suggests a software architecture for use of the package in a scenario with regular, periodical survey waves

Optical Investigation of GaNAs

A systematic study of the energy and time-resolved photoluminescence of GaInP/GaNxAs1-x double heterostructures has been performed for 0=x=1.3%. A large temperature-dependent optical-bowing coefficient (about 20-25 eV) is observed and the bandgap variation with temperature is found to depend on the nitrogen content. Finally, the minority-carrier lifetime is not simply related to the nitrogen content. Instead, the recombination rate is proportional to the majority-carrier concentration for x=0.3% and the carbon concentration for x=0.3%

Paperclips, circles, and six-legged spiders: An exploration of self-perceived and measured creativity among CS students

This paper presents an exploration of the creative potential of a small group of computer science students, how their scores on divergent production tests relate to their self-perceived creativity in certain domains, and how these both relate to their academic performance in a computer graphics programming course. It was found the higher the creativity on alternative uses tests the higher the grade the students achieved on the course, and the higher the creativity as measured by a figural divergent production test the higher their self-perceived creativity was across a set of domains related to computer science. The implications of these findings in terms of exactly what our assessments are measuring is discussed