The AV1 video compression format is developed by the Alliance for Open Media consortium. It achieves more than a 30% reduction in bit rate compared to its predecessor VP9 for the same decoded video quality. This article provides a technical overview of the AV1 codec design that enables the compression performance gains with considerations for hardware feasibility.

β-Alanine is an important precursor for the production of food additives, pharmaceuticals, and nitrogen-containing chemicals. Compared with the conventional chemical routes for β-alanine production, the biocatalytic routes using L-aspartate-α-decarboxylase (ADC) are more attractive when energy and environment are concerned. However, ADC's poorly understood properties and its inherent mechanism-based inactivation significantly limited the application of this enzyme. In this study, three genes encoding the ADC enzymes from Escherichia coli, Corynebacterium glutamicum, and Bacillus subtilis were overexpressed in E. coli. Their properties including specific activity, thermostability, and mechanism-based inactivation were characterized. The ADC enzyme from B. subtilis, which had higher specific activity and thermostability than the others, was selected for further study. In order to improve its activity and relieve its mechanism-based inactivation by molecular engineering so as to improve its catalytic stability, a high-throughput fluorometric assay of β-alanine was developed. From a library of 4000 mutated enzymes, two variants with 18-22% higher specific activity and 29-64% higher catalytic stability were obtained. The best variant showed 50% higher β-alanine production than the wild type after 8 h of conversion of L-aspartate, showing great potential for industrial biocatalytic production of β-alanine.

In this paper, we introduce a volumetric partitioning strategy based on a generalized sweeping framework to seamlessly partition the volume of an input triangle mesh into a collection of deformed cuboids. This is achieved by a user-designed volumetric harmonic function that guides the decomposition of the input volume into a sequence of two-manifold level sets. A skeletal structure whose corners correspond to corner vertices of a 2D parameterization is extracted for each level set. Corners are placed so that the skeletal structure aligns with features of the input object. Then, a skeletal surface is constructed by matching the skeletal structures of adjacent level sets. The surface sheets of this skeletal surface partition the input volume into the deformed cuboids. The collection of cuboids does not exhibit T-junctions, significantly simplifying the hexahedral mesh generation process, and in particular, it simplifies fitting trivariate B-splines to the deformed cuboids. Intersections of the surface sheets of the skeletal surface correspond to the singular edges of the generated hex-meshes. We apply our technique to a variety of 3D objects and demonstrate the benefit of the structure decomposition in data fitting.

Purpose -The purpose of this paper is to present methods for customized mapping and metadata transfer from DSpace to Online Computer Library Center (OCLC), which aims to improve Electronic Theses and Dissertations (ETD) work flow at libraries using DSpace to store theses and dissertations by automating the process of generating MARC records from Dublin Core (DC) metadata in DSpace and exporting them to OCLC. Design/methodology/approach -This paper discusses how the Shocker Open Access Repository (SOAR) at Wichita State University (WSU) Libraries and ScholarsArchive at Oregon State University (OSU) Libraries harvest theses data from the DSpace platform using the Metadata Harvester in MarcEdit developed by Terry Reese at OSU Libraries. It analyzes certain challenges in transformation of harvested data including handling of authorized data, dealing with data ambiguity and string processing. It addresses how these two institutions customize Library of Congress's XSLT (eXtensible Stylesheet Language Transformations) mapping to transfer DC metadata to MarcXML metadata and how they export MARC data to OCLC and Voyager. Findings -The customized mapping and data transformation for ETD data can be standardized while also requiring a case-by-case analysis. By offering two institutions' experiences, it provides information on the benefits and limitations for those institutions that are interested in using MarcEdit and customized XSLT to transform their ETDs from DSpace to OCLC and Voyager. Originality/value -The new method described in the paper can eliminate the need for double entry in DSpace and OCLC, meet local needs and significantly improve ETD work flow. It offers perspectives on repurposing and managing metadata in a standard and customizable way.