Time Encoding Using the Hyperbolic Secant Kernel

In the past few decades, the video broadcast ecosystem has gone through major changes; Originally transmitted using analog signals, it has been more and more transitioned toward digital, leveraging compression technologies and transport protocols, principally developed by MPEG. Along this way, the introduction of new video formats was achieved with standardization of new compression technologies for their better bandwidth preservation. Notably, SD with MPEG-2, HD with H.264, 4K/UHD with HEVC. In Brazil, the successive generations of digital broadcasting systems were developed by the SBTVD Forum, from TV-1.0 to TV-3.0 nowadays. The ambition of TV-3.0 is significantly higher than that of previous generations as it targets the delivery of IPbased signals for applications, such as 8K, HDR, virtual and augmented reality. To deliver such services, compressed video signals shall fit into a limited bandwidth, requiring even more advanced compression technologies. The Versatile Video Coding standard (H.266/VVC), has been finalized by the JVET committee in 2021 and is a relevant candidate to address the TV3.0 requirements. VVC is versatile by nature thanks to its dedicated tools for efficient compression of various formats, from 8K to 360°, and provides around 50% of bitrate saving compared to its predecessor HEVC. This paper presents the VVC-based compression system that has been proposed to the SBTVD call for proposals for TV-3.0. A technical description of VVC and an evaluation of its coding performance is provided. In addition, an end-to-end live transmission chain is demonstrated, supporting 4K real-time encoding and decoding with a low glass-to-glass latency.

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A tunable multicellular timer in bacterial consortia

10.1101/2020.10.24.353334 ◽

2020 ◽

Author(s):

Carlos Toscano-Ochoa ◽

Jordi Garcia-Ojalvo

Keyword(s):

Collective Behavior ◽

Bacterial Population ◽

Single Cells ◽

Bacterial Strains ◽

Intracellular Space ◽

Bacterial Consortia ◽

Robust Implementation ◽

Time Encoding ◽

Stationary Conditions ◽

Molecular Components

Processing time-dependent information requires cells to quantify the durations of past regulatory events and program the time span of future signals. Such timer mechanisms are difficult to implement at the level of single cells, however, due to saturation in molecular components and stochasticity in the limited intracellular space. Multicellular implementations, on the other hand, outsource some of the components of information-processing circuits to the extracellular space, and thereby might escape those constraints. Here we develop a theoretical framework, based on a trilinear coordinate representation, to study the collective behavior of a three-strain bacterial population under stationary conditions. This framework reveals that distributing different processes (in our case the production, detection and degradation of a time-encoding signal) across distinct bacterial strains enables the robust implementation of a multicellular timer. Our analysis also shows the circuit to be easily tunable by varying the relative frequencies of the bacterial strains composing the consortium.

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