Structure and mechanism of bactericidal mammalian perforin-2, an ancient agent of innate immunity

Perforin-2 (MPEG1) is thought to enable the killing of invading microbes engulfed by macrophages and other phagocytes, forming pores in their membranes. Loss of perforin-2 renders individual phagocytes and whole organisms significantly more susceptible to bacterial pathogens. Here, we reveal the mechanism of perforin-2 activation and activity using atomic structures of pre-pore and pore assemblies, high-speed atomic force microscopy, and functional assays. Perforin-2 forms a pre-pore assembly in which its pore-forming domain points in the opposite direction to its membrane-targeting domain. Acidification then triggers pore formation, via a 180° conformational change. This novel and unexpected mechanism prevents premature bactericidal attack and may have played a key role in the evolution of all perforin family proteins

The palisade layer of the poxvirus core is composed of flexible A10 trimers

Due to its asymmetric shape, size and compactness, the structure of the infectious mature virus (MV) of vaccinia virus (VACV), the best-studied poxvirus, remains poorly understood. Instead, subviral particles, in particular membrane-free viral cores, have been studied with cryo-electron microscopy. Here, we compared viral cores obtained by detergent stripping of MVs with cores in the cellular cytoplasm, early in infection. We focused on the prominent palisade layer on the core surface, combining cryo-electron tomography, subtomogram averaging and AlphaFold2 structure prediction. We showed that the palisade is composed of densely packed trimers of the major core protein A10. Trimers display a random order and their classification indicates structural flexibility. A10 on cytoplasmic cores is organized in a similar manner, indicating that the structures obtained in vitro are physiologically relevant. We discuss our results in the context of the VACV replicative cycle, and the assembly and disassembly of the infectious MV

Modeling, Evaluation, and Scale on Artificial Pedestrians: A Literature Review

Modeling pedestrian dynamics and their implementation in a computer are challenging and important issues in the knowledge areas of transportation and computer simulation. The aim of this article is to provide a bibliographic outlook so that the reader may have quick access to the most relevant works related to this problem. We have used three main axes to organize the article's contents: pedestrian models, validation techniques, and multiscale approaches. The backbone of this work is the classification of existing pedestrian models; we have organized the works in the literature under five categories, according to the techniques used for implementing the operational level in each pedestrian model. Then the main existing validation methods, oriented to evaluate the behavioral quality of the simulation systems, are reviewed. Furthermore, we review the key issues that arise when facing multiscale pedestrian modeling, where we first focus on the behavioral scale (combinations of micro and macro pedestrian models) and second on the scale size (from individuals to crowds). The article begins by introducing the main characteristics of walking dynamics and its analysis tools and concludes with a discussion about the contributions that different knowledge fields can make in the near future to this exciting area

EVALITA Evaluation of NLP and Speech Tools for Italian - December 17th, 2020

Welcome to EVALITA 2020! EVALITA is the evaluation campaign of Natural Language Processing and Speech Tools for Italian. EVALITA is an initiative of the Italian Association for Computational Linguistics (AILC, http://www.ai-lc.it) and it is endorsed by the Italian Association for Artificial Intelligence (AIxIA, http://www.aixia.it) and the Italian Association for Speech Sciences (AISV, http://www.aisv.it)

Online adaptace akustického modelu na řečníka s využitím systému pro rozpoznávání obličejů

We have proposed and evaluated a novel approach for online speaker adaptation of an acoustic model based on face recognition. Instead of traditionally used audio-based speaker identification we investigated the video modality for the task of speaker detection. A simulated on-line transcription created by a Large-Vocabulary Continuous Speech Recognition (LVCSR) system for online subtitling is evaluated utilizing speaker independent acoustic models, gender dependent models and models of particular speakers. In the experiment, the speaker dependent acoustic models were trained offline, and are switched online based on the decision of a face recognizer, which reducedWord Error Rate (WER) by 12% relatively compared to speaker independent baseline system