Waves are seen in the atmosphere, oceans, etc. As one of the most common natural phenomena, water waves attract the attention of researchers. For the shallow water waves, a (3+1)-dimensional ...generalized nonlinear evolution equation is hereby investigated via the symbolic computation. Based on the Hirota method, we present three bilinear auto-Bäcklund transformations, along with some soliton solutions. Our results depend on the water-wave coefficients in that equation.
Electroencephalogram (EEG) has been widely used in emotion recognition due to its high temporal resolution and reliability. Since the individual differences of EEG are large, the emotion recognition ...models could not be shared across persons, and we need to collect new labeled data to train personal models for new users. In some applications, we hope to acquire models for new persons as fast as possible, and reduce the demand for the labeled data amount. To achieve this goal, we propose a multisource transfer learning method, where existing persons are sources, and the new person is the target. The target data are divided into calibration sessions for training and subsequent sessions for test. The first stage of the method is source selection aimed at locating appropriate sources. The second is style transfer mapping, which reduces the EEG differences between the target and each source. We use few labeled data in the calibration sessions to conduct source selection and style transfer. Finally, we integrate the source models to recognize emotions in the subsequent sessions. The experimental results show that the three-category classification accuracy on benchmark SEED improves by 12.72% comparing with the nontransfer method. Our method facilitates the fast deployment of emotion recognition models by reducing the reliance on the labeled data amount, which has practical significance especially in fast-deployment scenarios.
In this paper, we propose a deep reinforcement learning (DRL)-based method that allows unmanned aerial vehicles (UAVs) to execute navigation tasks in large-scale complex environments. This technique ...is important for many applications such as goods delivery and remote surveillance. The problem is formulated as a partially observable Markov decision process (POMDP) and solved by a novel online DRL algorithm designed based on two strictly proved policy gradient theorems within the actor-critic framework. In contrast to conventional simultaneous localization and mapping-based or sensing and avoidance-based approaches, our method directly maps UAVs' raw sensory measurements into control signals for navigation. Experiment results demonstrate that our method can enable UAVs to autonomously perform navigation in a virtual large-scale complex environment and can be generalized to more complex, larger-scale, and three-dimensional environments. Besides, the proposed online DRL algorithm addressing POMDPs outperforms the state-of-the-art.
The global ocean sequesters a large amount of reduced carbon in dissolved organic molecules that can persist for centuries to millennia. The persistence of dissolved organic carbon (DOC) in the deep ...ocean has been attributed to inherently refractory molecules and to low concentrations of molecules, but the relative roles of molecular properties and molecular concentrations remain uncertain. We investigate both of these possibilities using bioassay experiments with unfiltered seawater collected from five depths (50–1500 m) at the Bermuda Atlantic Time- Series Study site. The microbial utilization of compositionally distinct forms of seawater DOC at in situ and elevated concentrations was determined. Microbial utilization of in situ organic carbon ranged from 6% to 7% in surface waters to 0% in deep water after 180 d. Additions of surface plankton-derived DOC (~18 μmol L−1), which was enriched in amino acids and carbohydrates, revealed substantial (50–75%) removal of the added DOC at all depths within 7 d. In sharp contrast, additions of C-18 isolated deep-sea DOC (~20 μmol L−1) showed insignificant or minimal utilization at all depths after 7 or 180 d, even when primed with labile substrates. These experiments demonstrate microbial communities from varying depths and environments in the ocean could rapidly utilize elevated concentrations of plankton-derived DOC, whereas these same microbes failed to utilize elevated concentrations of C-18 DOC. These results indicate molecular properties are the primary control on the microbial utilization of DOC in the ocean. Our findings imply a dynamic DOC reservoir with a flexible capacity for carbon sequestration in the global ocean.
From the motion of fish and birds, to migrating herds of ungulates, collective motion has attracted people for centuries. Active soft matter exhibits a plethora of emergent dynamic behaviors that ...mimic those of biological systems. Here we introduce an active system composed of dynamic dissipative solitons, i.e. directrons, which mimics the collective motion of living systems. Although the directrons are inanimate, artificial particle-like solitonic field configurations, they locally align their motions like their biological counterparts. Driven by external electric fields, hundreds of directrons are generated in a chiral nematic film. They start with random motions but self-organize into flocks and synchronize their motions. The directron flocks exhibit rich dynamic behaviors and induce population density fluctuations far larger than those in thermal equilibrium systems. They exhibit "turbulent" swimming patterns manifested by transient vortices and jets. They even distinguish topological defects, heading towards defects of positive topological strength and avoiding negative ones.
The availability of position information is of great importance in many commercial, public safety, and military applications. The coming years will see the emergence of location-aware networks with ...submeter accuracy, relying on accurate range measurements provided by wide bandwidth transmissions. In this two-part paper, we determine the fundamental limits of localization accuracy of wideband wireless networks in harsh multipath environments. We first develop a general framework to characterize the localization accuracy of a given node here and then extend our analysis to cooperative location-aware networks in Part II. In this paper, we characterize localization accuracy in terms of a performance measure called the squared position error bound (SPEB), and introduce the notion of equivalent Fisher information (EFI) to derive the SPEB in a succinct expression. This methodology provides insights into the essence of the localization problem by unifying localization information from individual anchors and that from a priori knowledge of the agent's position in a canonical form. Our analysis begins with the received waveforms themselves rather than utilizing only the signal metrics extracted from these waveforms, such as time-of-arrival and received signal strength. Hence, our framework exploits all the information inherent in the received waveforms, and the resulting SPEB serves as a fundamental limit of localization accuracy.
2D perovskites have been considered as promising candidates for optoelectronic devices due to their good optical and electronic properties compared to 3D perovskites with significantly higher ...stability. Considering the commercial applications involving displays, image sensors, and fluorescent anti‐counterfeiting labels, the patterning technique of 2D perovskites is urgently required. However, existing patterning approaches still have challenges in high‐resolution fabrication. Here, a facile femtosecond laser direct writing method to fabricate arbitrarily patterned 2D perovskite films with well‐defined profiles and uniform fluorescence properties is developed. The flexible, fine, and non‐thermal diffused patterning abilities of femtosecond laser facilitate diverse 2D perovskite patterns exhibiting bright emission without any pinholes and cracks, as well as high resolution of approximate 2 µm line width. Based on this efficient patterning technique, this study demonstrates fluorescent anti‐counterfeiting labels (quick response code embedded with microlines) based on 2D perovskite films with high humidity stability, which can be identified from 43% to 96% relative humidity. This high‐resolution, reliable, efficient, and facile patterning technique for 2D perovskites with high humidity stability provides a promising technical route for 2D perovskite‐based optoelectronic applications.
For practical applications of 2D perovskites, a femtosecond laser direct writing method for patterning of 2D perovskites is proposed. Benefiting from the flexible, fine, and non‐thermal diffused patterning capabilities of a femtosecond laser, diverse 2D perovskite patterns exhibit bright and uniform emission properties without any pinholes and cracks and a high resolution of approximate 2 µm line width.
A class of 3‐(azidomethyl)‐2H‐azirine has been obtained through a copper‐catalyzed diazidation of allenes and a subsequent azirination involving vinyl azides. A variety of functional groups in the ...allenes are well tolerated, providing a series of 3‐(azidomethyl)‐2H‐azirine motifs in 51%‐93% yields (26 examples).
The research field of liquid crystals and their applications is recently changing from being largely focused on display applications and optical shutter elements in various fields, to quite novel and ...diverse applications in the area of nanotechnology and nanoscience. Functional nanoparticles have recently been used to a significant extent to modify the physical properties of liquid crystals by the addition of ferroelectric and magnetic particles of different shapes, such as arbitrary and spherical, rods, wires and discs. Also, particles influencing optical properties are increasingly popular, such as quantum dots, plasmonic, semiconductors and metamaterials. The self-organization of liquid crystals is exploited to order templates and orient nanoparticles. Similarly, nanoparticles such as rods, nanotubes and graphene oxide are shown to form lyotropic liquid crystal phases in the presence of isotropic host solvents. These effects lead to a wealth of novel applications, many of which will be reviewed in this publication.
Histone lysine acetylation is well known for being important in the epigenetic regulation of gene expression in eukaryotic cells. Recent studies have uncovered a plethora of acetylated proteins ...involved in important metabolic pathways, such as photosynthesis and respiration in plants. Enzymes involved in histone acetylation and deacetylation are being identified as regulators of acetylation of metabolic enzymes. Importantly, key metabolites, such as acetyl-CoA and NAD+, are involved in protein acetylation and deacetylation processes, and their cellular levels may regulate the activity of histone acetyltransferases (HAT) and deacetylases (HDAC). Further research is required to determine whether and how HATs and HDACs sense cellular metabolite signals to control gene expression and metabolic enzyme activity through lysine acetylation and deacetylation.
Protein lysine acetylation has recently emerged as a widespread reversible modification occurring on histones and nonhistone proteins, including key metabolic enzymes.
Histone acetylation level is controlled by the activity of both histone acetyltransferases (HATs) and deacetylase (HDACs), some of which have been identified to acetylate or deacetylate nonhistone proteins.
Acetyl-CoA can act as a metabolic signal for cell growth by promoting histone acetylation at growth-related genes via regulating the activity of specific acetyltransferase, whereas the NAD+ level may influence NAD+-dependent Sirtuin 2 (SIR2) lysine deacetylases. Thus, HATs and HDACs may sense cellular metabolite levels to coordinate cellular energy and redox status with gene expression and metabolic activity to control plant growth.
PDF
