Genome-wide characterization of single-stranded DNA in rice.

Single-stranded DNA (ssDNA) is essential for various DNA-templated processes in both eukaryotes and prokaryotes. However, comprehensive characterizations of ssDNA still lag in plants compared to non-plant systems. Here, we conducted in situ S1-seq (ISS1-seq), with starting gDNA ranging from 5 µg to 250 ng, followed by comprehensive characterizations of ssDNA in rice (Oryza sativa L.). We found that ssDNA loci were substantially associated with a subset of non-B DNA structures and functional genomic loci. Subtypes of ssDNA loci had distinct epigenetic features. Importantly, ssDNA may act alone or partly coordinate with non-B DNA structures, functional genomic loci, or epigenetic marks to actively or repressively modulate gene transcription, which is genomic-region-dependent and associated with the distinct accumulation of RNA Pol II. Moreover, distinct types of ssDNA had differential impacts on the activities and evolution of TEs (especially common or conserved TEs) in the rice genome. Our study showcases an antibody-independent technique for characterizing non-B DNA structures or functional genomic loci in plants. It lays the groundwork and fills a crucial gap for further exploration of ssDNA, non-B DNA structures, or functional genomic loci, thereby advancing our understanding of their biology in plants.

R-loops act as regulatory switches modulating transcription of COLD-responsive genes in rice.

COLD is a major naturally occurring stress that usually causes complex symptoms and severe yield loss in crops. R-loops function in various cellular processes, including development and stress responses, in plants. However, how R-loops function in COLD responses is largely unknown in COLD susceptible crops like rice (Oryza sativa L.). We conducted DRIP-Seq along with other omics data (RNA-Seq, DNase-Seq and ChIP-Seq) in rice with or without COLD treatment. COLD treatment caused R-loop reprogramming across the genome. COLD-biased R-loops had higher GC content and novel motifs for the binding of distinct transcription factors (TFs). Moreover, R-loops can directly/indirectly modulate the transcription of a subset of COLD-responsive genes, which can be mediated by R-loop overlapping TF-centered or cis-regulatory element-related regulatory networks and lncRNAs, accounting for c. 60% of COLD-induced expression of differential genes in rice, which is different from the findings in Arabidopsis. We validated two R-loop loci with contrasting (negative/positive) roles in the regulation of two individual COLD-responsive gene expression, as potential targets for enhanced COLD resistance. Our study provides detailed evidence showing functions of R-loop reprogramming during COLD responses and provides some potential R-loop loci for genetic and epigenetic manipulation toward breeding of rice varieties with enhanced COLD tolerance.

Does the promotion pressure on local officials matter for regional carbon emissions? Evidence based on provincial-level leaders in China.

This paper constructs data from 30 provinces in mainland China from 1997 to 2016 and mainly adopts panel data fixed effects models to investigate how the promotion pressure on local officials affects regional carbon emissions. Our empirical results show that the relationship between the promotion pressure on local officials and regional carbon emissions has a dynamic evolution characteristic during our research period. Specifically, the promotion pressure on local officials is positively associated with regional carbon emissions before 2009; however, this relationship weakened after China's carbon emission regulatory policies were strengthened in 2010. Furthermore, our heterogeneity analysis results show that the effect of promotion pressure on regional carbon emissions is moderated by the regional industrial structure, the economic development level, regional innovation capability, the tenure of officials and the age of officials. The conclusions of this study are helpful for understanding the driving factors of regional carbon emissions from the political economy perspective, and they also have implications for the formulation of performance evaluation and carbon emission reduction policies.

Propagation properties of spatiotemporal chirped Airy Gaussian vortex wave packets in a quadratic index medium.

A type of chirped Airy Gaussian vortex (CAiGV) localized wave packets in a quadratic index medium are studied by solving the paraxial differential equation. For the first time, the propagation properties of spatiotemporal CAiGV light bullets in the quadratic index medium are demonstrated. Some typical examples of the obtained solutions are based on the temporal and spatial chirp parameters, the initial velocity, the distribution factor, and the topological charge. The radiation force of the spatial CAiGV wave packet on a Rayleigh dielectric particle has the periodically reversion and recovery abilities due to the quadratic potential. What we report here can obtain different radiation force trajectory and may have potential application in optical tweezing and bio-medical field.

Self-accelerating Airy-Ince-Gaussian and Airy-Helical-Ince-Gaussian light bullets in free space.

The evolution of the three-dimensional (3D) self-accelerating Airy-Ince-Gaussian (AiIG) and Airy-Helical-Ince-Gaussian (AiHIG) light bullets is investigated by solving the (3+1)D linear spatiotemporal evolution equation of an optical field analytically. As far as we know, the numerical experimental demonstrations of the Ince-Gaussian (IG) and Helical-Ince-Gaussian (HIG) beams in various modes are first developed to study the evolution characteristics of the different 3D spatiotemporal light bullets. A conclusion can be drawn that the different photoelastics, pulse stacked, boundary, elliptical ring and physically separated in-line vortices can be achieved by adjusting the ellipticity, the evolution distance and the mode-number of light bullets.

Propagation of sharply autofocused ring Airy Gaussian vortex beams.

Controlling the focal length and the intensity of the optical focus in the media is an important task. Here we investigate the propagation properties of the sharply autofocused ring Airy Gaussian vortex beams numerically and some numerical experiments are performed. We introduce the distribution factor b into the initial beams, and discuss the influences for the beams. With controlling the factor b, the beams that tend to a ring Airy vortex beam with the smaller value, or a hollow Gaussian vortex beam with the larger one. By a choice of initial launch condition, we find that the number of topological charge of the incident beams, as well as its size, greatly affect the focal intensity and the focal length of the autofocused ring Airy Gaussian vortex beams. Furthermore, we show that the off-axis autofocused ring Airy Gaussian beams with vortex pairs can be implemented.

A Soft Inductive Bimodal Sensor for Proprioception and Tactile Sensing of Soft Machines.

The somatosensory system is crucial for living beings to survive and thrive in complex environments and to interact with their surroundings. Similarly, rapidly developed soft robots need to be aware of their own posture and detect external stimuli. Bending and force sensing are key for soft machines to achieve embodied intelligence. Here, we present a soft inductive bimodal sensor (SIBS) that uses the strain modulation of magnetic permeability and the eddy-current effect for simultaneous bidirectional bending and force sensing with only two wires. The SIBS is made of a flexible planar coil, a porous ferrite film, and a soft conductive film. By measuring the inductance at two different frequencies, the bending angle and force can be obtained and decoupled. Rigorous experiments revealed that the SIBS can achieve high resolution (0.44° bending and 1.09 mN force), rapid response, excellent repeatability, and high durability. A soft crawling robot embedded with one SIBS can sense its own shape and interact with and respond to external stimuli. Moreover, the SIBS is demonstrated as a wearable human-machine interaction to control a crawling robot via wrist bending and touching. This highlights that the SIBS can be readily implemented in diverse applications for reliable bimodal sensing.

Spatiotemporal Airy Ince-Gaussian wave packets in strongly nonlocal nonlinear media.

The self-accelerating Airy Ince-Gaussian (AiIG) and Airy helical Ince-Gaussian (AihIG) wave packets in strongly nonlocal nonlinear media (SNNM) are obtained by solving the strongly nonlocal nonlinear Schrödinger equation. For the first time, the propagation properties of three dimensional localized AiIG and AihIG breathers and solitons in the SNNM are demonstrated, these spatiotemporal wave packets maintain the self-accelerating and approximately non-dispersion properties in temporal dimension, periodically oscillating (breather state) or steady (soliton state) in spatial dimension. In particular, their numerical experiments of spatial intensity distribution, numerical simulations of spatiotemporal distribution, as well as the transverse energy flow and the angular momentum in SNNM are presented. Typical examples of the obtained solutions are based on the ratio between the input power and the critical power, the ellipticity and the strong nonlocality parameter. The comparisons of analytical solutions with numerical simulations and numerical experiments of the AiIG and AihIG optical solitons show that the numerical results agree well with the analytical solutions in the case of strong nonlocality.