Compressed sensing has become a widely accepted paradigm to construct high dimensional cluster expansion models used for statistical mechanical studies of atomic configuration in complex multicomponent crystalline materials. However, strict sampling requirements necessary to obtain minimal coherence measurements for compressed sensing to guarantee accurate estimation of model parameters are difficult and in some cases impossible to satisfy due to the inability of physical systems to access certain configurations. Nevertheless, the dependence of energy on atomic configuration can still be adequately learned without these strict requirements by using compressed sensing by way of coherent measurements using redundant function sets known as frames. We develop a particular frame constructed from the union of all occupancy-based cluster expansion basis sets. We illustrate how using this highly redundant frame yields sparse expansions of the configuration energy of complex oxide materials that are competitive and often surpass the prediction accuracy and sparsity of models obtained from standard cluster expansions.
Remembering a lot of things at the same time is difficult. As an experiment, read these numbers: 07041776. Then, close your eyes and try to say them aloud, in order. How did you do? We would guess that you remembered around half of the numbers. Now, try again but think of the same numbers as a date: 07-04-1776. Did you remember more of the numbers this time? You just demonstrated something called working memory. Working memory (“WM” for short) is the ability to hold onto and process pieces of information. WM activates when you experience and remember events in your life, learn new facts, talk to people, read, and do math. WM is a basic human behavior. As shown in the numbers experiment, WM has limited capacity. How does the brain support WM? And, what is happening in the brain that limits our capacity to store multiple memories at the same time?
Using international data starting in 1957, we construct a sample of cases where fast-growing economies slow down. The evidence suggests that rapidly growing economies slow down significantly, in the sense that the growth rate downshifts by at least 2 percentage points, when their per capita incomes reach around US$ 17,000 in year-2005 constant international prices, a level that China should achieve by or soon after 2015. Among our more provocative findings is that growth slowdowns are more likely in countries that maintain undervalued real exchange rates.
Abstract Temp.‐programmed desorption spectroscopic studies show that while the chemisorption of NO is suppressed with increasing catalyst reduction temp. in a manner similar to that for H 2 and C0 chemisorption, the amount of NO adsorbed is always greater than that of H 2 or C0.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Abstract High‐quality wurtzite In‐rich In 1− x Ga x N (0 ≤ x ≤ 0.5) and In 1− y Al y N films (0 ≤ y ≤ 0.25) were grown on sapphire substrates by molecular‐beam epitaxy. Optical absorption, photoluminescence and photomodulated reflectance measurements demonstrate that the fundamental bandgap for InN is only about 0.7 eV. The free electron effective mass is found to vary with free electron concentration, the consequence of a strongly non‐parabolic conduction band caused by the k · p interaction with the valence bands across the narrow bandgap. The bandgap gradually increases with increasing Ga or Al content in In 1− x Ga x N or In 1− y Al y N alloys. The composition dependencies of the bandgaps are well described by bowing parameters of 1.4 eV for In 1− x Ga x N and 3.0 eV for In 1− y Al y N. The direct gaps of the group III‐nitride alloy system cover a very broad spectral range from the near‐infrared in InN to deep‐ultraviolet in AlN. This offers unique opportunities for the use of these alloys in a wide range of optoelectronic and photovoltaic devices. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The immune system can summon a variety of defenses against invaders from the outside. Among these deterrents are three types of killer lymphocytes that attack and lyse cellular targets. One type consists of cytotoxic, or CD8, T cells with α/β antigen receptors that interact with the HLA class I glycoproteins on nearly all cells. These HLA molecules bind to peptides derived from intracellular antigens, such as viral proteins, and display them on the cell surface. Binding of the α/β antigen receptor to complexes of HLA class I molecules and peptide fragments of an invading virus induces the T lymphocyte to . . .
