Search

We investigate effective interference management for Low Earth Orbit (LEO) satellite networks that provide downlink services to ground users and share the same frequency spectrum range. Since there are multi-group LEO satellites with different constellation orbits, the ground users will experience time-varying interference due to the overlapping of main/side lobes of the satellite beams, which becomes even more challenging when the interfering satellites cannot communicate directly. To address the problem, we consider two LEO satellite groups that provide communication service in the same ground area, while competing for communication resources. We develop solutions that maximize the throughput and manage the time-varying interference under a certain level, without explicit message exchanges between the satellite groups. By exploiting statistical learning and deep reinforcement learning techniques, we develop learning-based resource allocation schemes and evaluate their performance through extensive simulations. We show their effectiveness under different reward settings and different interference managements, and demonstrate that a Deep Q-Network (DQN)-based scheme can achieve the close-to-optimal performance.

Nuclear-encoded light-harvesting chlorophyll- and carotenoid-binding proteins (LHCPs) are imported into the chloroplast and transported across the stroma to thylakoid membrane assembly sites by the chloroplast signal recognition particle (CpSRP) pathway. The LHCP translocation defect (LTD) protein is essential for the delivery of imported LHCPs to the CpSRP pathway in Arabidopsis. However, the function of the LTD protein in Chlamydomonas reinhardtii has not been investigated. Here, we generated a C. reinhardtii ltd (Crltd) knockout mutant by using CRISPR-Cas9, a new target-specific knockout technology. The Crltd1 mutant showed a low chlorophyll content per cell with an unusual increase in appressed thylakoid membranes and enlarged cytosolic vacuoles. Profiling of thylakoid membrane proteins in the Crltd1 mutant showed a more severe reduction in the levels of photosystem I (PSI) core proteins and absence of functional LHCI compared with those of photosystem II, resulting in a much smaller PSI pool size and diminished chlorophyll antenna size. The lack of CrLTD did not prevent photoautotrophic growth of the cells. These results are substantially different from those for Arabidopsis ltd null mutant, indicating LTD function in LHCP delivery and PSI assembly may not be as stringent in C. reinhardtii as it is in higher plants. [ABSTRACT FROM AUTHOR]

In several Korean dialects, domain-initial nasal onsets undergo denasalization as a recent sound change. Nasal stops may be realized as prevoiced or even devoiced stops. This makes it necessary to examine the interplay of phonetic properties of the denasalized and the three oral stop series as a whole, in synchrony and diachrony. What are their concomitant and conflicting properties? Our study provides a bigger picture of the laryngeal contrast in Seoul and Gyeonggi Korean by examining the acoustic distributions related to the laryngeal properties of the four stop series, using acoustic and electroglottographic data. VOT and f0 play important roles in the distinction of the four stop series, in line with previous studies. While the contribution of voice quality is relatively minor, we show that it plays an essential role of disambiguation when the VOT–f0 space gets crowded: When lenis stops can be confused with other stops, there is an enhancement of breathy voice. Finally, we discuss stop variation according to prosodic contexts. We highlight the basis of both syntagmatic variation and paradigmatic contrast in their phonetic implementations. They illustrate a constant reorganization to reconcile contrast maintenance with constraints from articulatory and perceptual systems, as well as language-specific structures.

A key floral activator, FT, integrates stimuli from long-day, vernalization, and autonomous pathways and triggers flowering by directly regulating floral meristem identity genes in Arabidopsis (Arabidopsis thaliana). Since a small amount of FT transcript is sufficient for flowering, the FT level is strictly regulated by diverse genes. In this study, we show that WEREWOLF (WER), a MYB transcription factor regulating root hair pattern, is another regulator of FT. The mutant wer flowers late in long days but normal in short days and shows a weak sensitivity to vernalization, which indicates that WER controls flowering time through the photoperiod pathway. The expression and double mutant analyses showed that WER modulates FT transcript level independent of CONSTANS and FLOWERING LOCUS C. The histological analysis of WER shows that it is expressed in the epidermis of leaves, where FT is not expressed. Consistently, WER regulates not the transcription but the stability of FT mRNA. Our results reveal a novel regulatory mechanism of FT that is non cell autonomous. [ABSTRACT FROM AUTHOR]

A key floral activator, FT, integrates stimuli from long-day, vernalization, and autonomous pathways and triggers flowering by directly regulating floral meristem identity genes in Arabidopsis (Arabidopsis thaliana). Since a small amount of FT transcript is sufficient for flowering, the FT level is strictly regulated by diverse genes. In this study, we show that WEREWOLF (WER), a MYB transcription factor regulating root hair pattern, is another regulator of FT. The mutant wer flowers late in long days but normal in short days and shows a weak sensitivity to vernalization, which indicates that WER controls flowering time through the photoperiod pathway. The expression and double mutant analyses showed that WER modulates FT transcript level independent of CONSTANS and FLOWERING LOCUS C. The histological analysis of WER shows that it is expressed in the epidermis of leaves, where FT is not expressed. Consistently, WER regulates not the transcription but the stability of FT mRNA. Our results reveal a novel regulatory mechanism of FT that is non cell autonomous. [ABSTRACT FROM AUTHOR]