Detecting and tracking high-velocity plasmoids produced by a magnetized coaxial plasma gun in visible images.

The compact torus (CT) injection device, widely known as a magnetized coaxial plasma gun, creates self-contained magnetic field structures, known as plasmoids, which exhibit high densities and velocities. Owing to its remarkable energy density, the CT injection device holds immense potential for tokamak core fueling, rendering it promising for future fusion reactor applications. This paper presents a novel algorithm, comprising a segmentation module based on the UNet neural network and a tracking module leveraging the simple online and real-time tracking (SORT) algorithm, developed for detecting and tracking plasmoids in visible images.

Kinetic characteristics of transcriptional bursting in a complex gene model with cyclic promoter structure.

While transcription often occurs in a bursty manner, various possible regulations can lead to complex promoter patterns such as promoter cycles, giving rise to an important question: How do promoter kinetics shape transcriptional bursting kinetics? Here we introduce and analyze a general model of the promoter cycle consisting of multi-OFF states and multi-ON states, focusing on the effects of multi-ON mechanisms on transcriptional bursting kinetics. The derived analytical results indicate that burst size follows a mixed geometric distribution rather than a single geometric distribution assumed in previous studies, and ON and OFF times obey their own mixed exponential distributions. In addition, we find that the multi-ON mechanism can lead to bimodal burst-size distribution, antagonistic timing of ON and OFF, and diverse burst frequencies, each further contributing to cell-to-cell variability in the mRNA expression level.