Electron Spin Decoherence in Bulk and Quantum Well Zincblende Semiconductors

A theory for longitudinal (T1) and transverse (T2) electron spin coherence times in zincblende semiconductor quantum wells is developed based on a non-perturbative nanostructure model solved in a fourteen-band restricted basis set. Distinctly different dependences of coherence times on mobility, quantization energy, and temperature are found from previous calculations. Quantitative agreement between our calculations and measurements is found for GaAs/AlGaAs, InGaAs/InP, and GaSb/AlSb quantum wells.Comment: 11 pages, 3 figure

Open data from the third observing run of LIGO, Virgo, KAGRA, and GEO

The global network of gravitational-wave observatories now includes five detectors, namely LIGO Hanford, LIGO Livingston, Virgo, KAGRA, and GEO 600. These detectors collected data during their third observing run, O3, composed of three phases: O3a starting in 2019 April and lasting six months, O3b starting in 2019 November and lasting five months, and O3GK starting in 2020 April and lasting two weeks. In this paper we describe these data and various other science products that can be freely accessed through the Gravitational Wave Open Science Center at https://gwosc.org. The main data set, consisting of the gravitational-wave strain time series that contains the astrophysical signals, is released together with supporting data useful for their analysis and documentation, tutorials, as well as analysis software packages

Palladium-Catalyzed Decarboxylative Formal (4 + 2) Cycloaddition of Vinyl Benzoxazinanones with 3-Nitroindoles

© 2020. Thieme. All rights reserved. A diastereoselective palladium-catalyzed dearomative formal (4 + 2) cycloaddition between vinyl benzoxazinanones and 3-nitroindoles has been developed. This reaction provides a concise route to tetrahydro-5 H-indolo[2,3-b ]quinolines in excellent yield (up to 94%) and diastereoselectivity (up to \u3e98:2), with versatile functional handles including vinyl, nitro, and free NH groups

Synthesis of 1, 4-benzodiazepines and 1, 4-benzothiazepines

This chapter gives an overview of recent developments in the synthesis of 1, 4-benzodiazepines and 1, 4-benzothiazepines utilizing readily available reactants under practical synthetic procedures

DFT Mechanistic Insights into the Ni(II)-Catalyzed Enantioselective Arylative Cyclization of Tethered Allene-Ketones

Density functional theory (DFT) has provided a detailed mechanistic picture for the redox neutral nickel(II)-catalyzed arylative cyclization reactions of a tethered allene-ketone with arylboronic acids. A mechanistic rationale for the high diastereo- and enantioselectivity achieved experimentally at high reaction temperature was uncovered through modeling the reaction with a chiral ligand and the predicted stereochemical outcome corroborates with experimental results. An unprecedented mechanism for the base-free organoboron transmetalation was revealed and the regioselectivity of migratory insertion of tethered allene-ketones as well as the stability of the possible allylnickel isomers (σ-allyl vs π-allyl) were clarified. The multifaceted nature of the reaction is revealed with certain elementary steps preferring cationic compared to the neutral state

Object learning improves feature extraction but does not improve feature selection

A single glance at your crowded desk is enough to locate your favorite cup. But finding an unfamiliar object requires more effort. This superiority in recognition performance for learned objects has at least two possible sources. For familiar objects observers might: 1) select more informative image locations upon which to fixate their eyes, or 2) extract more information from a given eye fixation. To test these possibilities, we had observers localize fragmented objects embedded in dense displays of random contour fragments. Eight participants searched for objects in 600 images while their eye movements were recorded in three daily sessions. Performance improved as subjects trained with the objects: The number of fixations required to find an object decreased by 64% across the 3 sessions. An ideal observer model that included measures of fragment confusability was used to calculate the information available from a single fixation. Comparing human performance to the model suggested that across sessions information extraction at each eye fixation increased markedly, by an amount roughly equal to the extra information that would be extracted following a 100% increase in functional field of view. Selection of fixation locations, on the other hand, did not improve with practice