A non-Hermitian Weyl equation indispensably requires a three-dimensional (3D) real/synthetic space, and it is thereby perceived that a Weyl exceptional ring (WER) will not be present in thermal diffusion given its purely dissipative nature. Here, we report a recipe for establishing a 3D parameter space to imitate thermal spinor field. Two orthogonal pairs of spatiotemporally modulated advections are employed to serve as two synthetic parameter dimensions, in addition to the inherent dimension corresponding to heat exchanges. We first predict the existence of WER in our hybrid conduction–advection system and experimentally observe the WER thermal signatures verifying our theoretical prediction. When coupling two WERs of opposite topological charges, the system further exhibits surface-like and bulk topological states, manifested as stationary and continuously changing thermal processes, respectively, with good robustness. Our findings reveal the long-ignored topological nature in thermal diffusion and may empower distinct paradigms for general diffusion and dissipation controls.
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Summary In maize, 24‐nt phased, secondary small interfering RNAs (phasiRNAs) are abundant in meiotic stage anthers, but their distribution and functions are not precisely known.
Using laser capture microdissection, we analyzed tapetal cells, meiocytes and other somatic cells at several stages of anther development to establish the timing of 24‐
PHAS precursor transcripts and the 24‐nt phasiRNA products.By integrating RNA and small RNA profiling plus single‐molecule and small RNA FISH (smFISH or sRNA‐FISH) spatial detection, we demonstrate that the tapetum is the primary site of 24‐
PHAS precursor andDcl5 transcripts and the resulting 24‐nt phasiRNAs. Interestingly, 24‐nt phasiRNAs accumulate in all cell types, with the highest levels in meiocytes, followed by tapetum.Our data support the conclusion that 24‐nt phasiRNAs are mobile from tapetum to meiocytes and to other somatic cells. We discuss possible roles for 24‐nt phasiRNAs in anther cell types.
