GP-RARS: evolving controllers for the Robot Auto Racing Simulator

We use evolutionary computation techniques to create real-time reactive controllers for a race-car simulation game: RARS (Robot Auto Racing Simulator). Using genetic programming to evolve driver controllers, we create highly generalized game-playing agents, able to outperform most human-crafted controllers and all machine-designed ones on a variety of game tracks.     

Chiral Thin Films of Metal Oxide

In this paper, we describe for the first time the synthesis of new chiral nanosized metal oxide surfaces based on chiral self‐assembled monolayers (SAMs) coated with metal oxide (TiO₂) nanolayers. In this new type of nanosize chiral surface, the metal oxide nanolayers enable the protection of the chiral self‐assembled monolayers while preserving their enantioselective nature. The chiral nature of the SAM/TiO₂ films was characterized by variety of unique techniques, such as second‐harmonic generation circular dichroism (SHG‐CD), quartz crystal microbalance, and chiral adsorption measurements with circular dichroism spectroscopy. The chiral resolution abilities of the SAMs coated with metal oxide (TiO₂) nanolayers were investigated in the crystallization of a racemic mixture of threonine and glutamic acid. Our proposed methodology for the preparation of nanoscale chiral surfaces described in this article could open up opportunities in other fields of chemistry, such as chiral catalysis.     

Another form of the transmission function

The transmission function describes the passage of the electric current from one point of an electric circuit to another. By now, this is also applied to molecules which are potential candidates for uses in the molecular electronics. We mean the modern branch of electronics which has a goal of reducing the sizes of its devices down to molecular ones and planning indeed to apply single molecules as conducting wires and functional components of microcircuits. For calculating the transmission function, some authors utilize the well-known idea of representing a molecule by a (molecular) graph, which allows them to apply for treating the latter also powerful methods of spectral graph theory. For instance, we refer to the paper by Fowler et al. (Chem Phys Lett. 465 2008) 142–146, where one such expression for this function is given. Our objective is to demonstrate that the same calculational result can be obtained using a different set of characteristic polynomials of graphs (which also slightly reduces a mathematical notation). Specifically, we apply one theorem of Kolmykov to the basic formula derived by these authors.     

Phased cycles

We define a phased graph G to yield an adjacency matrix A(G) having general magnitude-1 values in the same locations as the usual unphased case, but subject to the restriction that A be Hermitian. Some characteristics of phased cycles, their eigenspectra, their symmetry, and their net energy are contemplated and described.     

Piecewise adiabatic population transfer in a molecule via a wave packet

We propose a class of schemes for robust population transfer between quantum states that utilize trains of coherent pulses, thus forming a generalized adiabatic passage via a wave packet. We study piecewise stimulated Raman adiabatic passage with pulse-to-pulse amplitude variation, and piecewise chirped Raman passage with pulse-to-pulse phase variation, implemented with an optical frequency comb. In the context of production of ultracold ground-state molecules, we show that with almost no knowledge of the excited potential, robust high-efficiency transfer is possible.     

Scale-free human migration and the geography of social networks

The “gravitational law of social interaction”, by which the probability of a social link decreases inversely with the square of the geographic distance, has been recently documented. The source of this spatial property of social networks, however, is yet unknown. The formation of social links is related to human dynamics both on the day-to-day, typically small scale, level of mobility, and on larger scale migration (or reallocation) movements. In this study we analyze human migration patterns by investigating the migration of 46.8 million individuals across the US during 1995-2000. We find that the probability of migration decreases as a power law of the distance, with exponent −1. We show that this finding offers an explanation for the gravitational law of social interaction. Possible explanations and implications of the scale-free migration pattern are discussed.     

An Apparatus for Production of Isotopically and Spin-Enriched Hydrogen for Induced Polarization Studies

An apparatus for the production of hydrogen for hydrogenation-induced polarization studies was developed. The apparatus provides hydrogen gas from a solid source, thereby simplifying the requirement for siting of the apparatus. The produced hydrogen can be either isotopically enriched (with deuterium) or spin-enriched (with parahydrogen). These specialty gases were produced at small predetermined quantities and ambient pressure. The properties of the hydrogen mixtures were characterized by gas-phase nuclear magnetic resonance. The T ₁ of the hydrogen mixtures (3.7 ms) was not affected by para-enrichment. The line width of the hydrogen signal in the para-enriched mixture was 34% larger. The reaction of ethyl propiolate hydrogenation served to evaluate the performance in terms of the ability to create hyperpolarized states. In this reaction, a polarization of 11.2% was measured for protons. Consecutive alkene hydrogenations as well as hydrogenations of the catalyst ligand resulted in additional hyperpolarized signals which were systematically assigned.     

A short proof of the jordan decomposition theorem

We present a short proof of the Jordan Decomposition Theorem     

2‐Chloro‐4,6‐di­methoxy‐1,3,5‐triazine

The mol­ecules of 2‐chloro‐4,6‐di­methoxy‐1,3,5‐triazine, C₅H₆ClN₃O₂, lie on a crystallographic mirror plane. There is a close contact of 3.180 (3) Å between one of the methyl C atoms and the N atom of a neighboring mol­ecule. Differential scanning calorimetry measurements show that methyl rearrangement does not take place in the solid state, despite the close proximity of the methyl group to the N atom.