•Combined with the error reconstruction rate, an adaptive VMD technology is developed and used for data preprocessing.•Two mainstream deep learning methods (LSTM, DBN) are used as sub-series ...predictors, and the classic PSO algorithm is utilized to determine the number of neurons in the DBN network.•A novel hybrid prediction model based on the PSO-DBN nonlinear combination mechanism is proposed.
Wind power forecasting plays a vital role in enhancing the efficiency of power grid operation and increasing the competitiveness of power market. In this paper, a novel hybrid forecasting model is developed by using the decomposition strategy, nonlinear weighted combination, and two deep learning models to overcome the drawbacks of the linear weighted combination and further enhance wind power forecasting accuracy and stability. Firstly, the variational mode decomposition (VMD) technique is employed to decompose the original wind power series to extract local features. Then, the long short-term memory neural networks (LSTM) and deep belief networks based on particle swarm optimization (PSO-DBN) are utilized to construct sub-series prediction models. Finally, the multiple sub-series forecasting models are integrated by a nonlinear weighted combination method based on PSO-DBN to construct a hybrid model for short-term wind power forecasting. To verify the performance of the developed forecasting model, wind speed data of 10 min from a wind farm in Shaanxi Dingbian, China are selected as case studies. The results show that the proposed method in this paper is more effective than other existing methods.
How homochirality concerning biopolymers (DNA/RNA/proteins) could have originally occurred (i.e., arisen from a non-life chemical world, which tended to be chirality-symmetric) is a long-standing ...scientific puzzle. For many years, people have focused on exploring plausible physic-chemical mechanisms that may have led to prebiotic environments biased to one chiral type of monomers (e.g., D-nucleotides against L-nucleotides; L-amino-acids against D-amino-acids)-which should have then assembled into corresponding polymers with homochirality, but as yet have achieved no convincing advance. Here we show, by computer simulation-with a model based on the RNA world scenario, that the biased-chirality may have been established at polymer level instead, just deriving from a racemic mixture of monomers (i.e., equally with the two chiral types). In other words, the results suggest that the homochirality may have originated along with the advent of biopolymers during the origin of life, rather than somehow at the level of monomers before the origin of life.
•A novel numerical method to simulate cavitation induced by long-pulsed laser.•The processes of laser radiation, vaporization, and bubble/fluid dynamics are simulated simultaneously.•An embedded ...boundary method is proposed for laser-fluid coupling, well-posed with 2nd-order accuracy.•The level set method is combined with a phase transition law to track continuous vaporization.•Predictive capability demonstrated by simulations of different laser experiments.
A computational method for simulating thermal cavitation induced by long-pulsed laser is presented. This method accounts for the absorption of laser light by a liquid, the formation of vapor bubbles due to localized heating, and the dynamics of the bubbles and the surrounding liquid. The physical model combines the Euler equations for a compressible inviscid two-phase fluid flow, a reduced form of the radiative transfer equation for laser radiation, and a local thermodynamic model of vaporization. The Euler equations are solved using the FInite Volume method with Exact two-phase Riemann solvers (FIVER). Following this method, numerical fluxes across phase boundaries are computed by constructing and solving one-dimensional bimaterial Riemann problems. The paper focuses on numerical methods for coupling the laser and fluid governing equations and tracking the vapor bubbles. An embedded boundary finite volume method is proposed to solve the laser radiation equation on the same mesh created for the Euler equations, which usually does not resolve the boundary and propagation directions of the laser beam. To impose boundary conditions, ghost nodes outside the laser domain are populated by mirroring and interpolation techniques. The existence and uniqueness of solution are proved for the two-dimensional case, leveraging the special geometry of the laser domain. The order of accuracy of the method is also proved, and verified using numerical tests. A method of latent heat reservoir is proposed to predict the onset of vaporization, which accounts for the accumulation and release of latent heat. A unique challenge associated with long-pulsed laser is that the dynamics of vapor bubbles is driven not only by the inertia of the bubble nuclei, but also by the continuation of vaporization. In this work, the localized level set method is employed to track the bubble surface, and a method of local correction and reinitialization is proposed to account for continuous phase transitions. Several numerical tests are presented to verify the convergence of these methods. Two realistic simulations of laser-induced cavitation are presented at the end, showing that the computational method is able to capture the key phenomena in these events, including non-spherical bubble expansion, shock waves, and the “Moses effect”.
Left bundle branch area pacing (LBBAP), a new pacing approach, lacks adequate evaluation.
To assess the feasibility, safety, and acute effect of permanent LBBAP in patients with atrioventricular ...block (AVB).
A total of 33 AVB patients with indications for ventricular pacing were recruited. Electrocardiograms, pacing parameters, echocardiographic measurements, and complications associated with LBBAP were evaluated perioperatively and at 3-month follow-up. Successful LBBAP was defined as a paced QRS morphology of right bundle branch block pattern in lead V
and QRS duration (QRSd) less than 130 ms.
LBBAP was successfully performed in 90.9% (30/33) of patients (mean age: 55.1 ± 18.5 years; 66.7% male). The mean capture threshold was similar during the procedure (0.76 ± 0.26 V at 0.4 ms) and at the 3-month follow-up (0.64 ± 0.20 V at 0.4 ms). The paced QRSd was 112.8 ± 10.9 ms during the procedure and 116.8 ± 10.4 ms at the 3-month follow-up. Baseline left or right bundle branch block was corrected (intrinsic QRSd 153.3 ± 27.8 ms vs paced QRSd 122.2 ± 9.9 ms) with a success rate of 68.7% (11/16). One ventricular septal lead perforation occurred soon after the procedure with characteristics of pacing failure, and lead revision was successful. Cardiac function and left ventricular synchronization by 2-dimensional echocardiographic strain imaging at the 3-month follow-up slightly improved compared with that at baseline.
Permanent LBBAP yielded a stable threshold, a narrow QRSd, and preserved left ventricular synchrony with few complications. Our preliminary results indicate that LBBAP holds promise as an attractive physiological pacing strategy for AVB.
Clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (Cas9) is a precise genome manipulating technology that can be programmed to induce double-strand break (DSB) ...in the genome wherever needed. After nuclease cleavage, DSBs can be repaired by non-homologous end joining (NHEJ) or homology-directed repair (HDR) pathway. For producing targeted gene knock-in or other specific mutations, DSBs should be repaired by the HDR pathway. While NHEJ can cause various length insertions/deletion mutations (indels), which can lead the targeted gene to lose its function by shifting the open reading frame (ORF). Furthermore, HDR has low efficiency compared with the NHEJ pathway. In order to modify the gene precisely, numerous methods arose by inhibiting NHEJ or enhancing HDR, such as chemical modulation, synchronized expression, and overlapping homology arm. Here we focus on the efficiency and other considerations of these methodologies.
Robust diffusion adaptive estimation algorithms based on the maximum correntropy criterion (MCC), including adapt then combine MCC and combine then adapt MCC, are developed to deal with the ...distributed estimation over network in impulsive (long-tailed) noise environments. The cost functions used in distributed estimation are in general based on the mean square error (MSE) criterion, which is desirable when the measurement noise is Gaussian. In non-Gaussian situations, especially for the impulsive-noise case, MCC based methods may achieve much better performance than the MSE methods as they take into account higher order statistics of error distribution. The proposed methods can also outperform the robust diffusion least mean p-power (DLMP) and diffusion minimum error entropy (DMEE) algorithms. The mean and mean square convergence analysis of the new algorithms are also carried out.
Corresponding to life's two distinct aspects: Darwinian evolution and self-sustainment, the origin of life should also split into two issues: the origin of Darwinian evolution and the arising of ...self-sustainment. Because the "self-sustainment" we concern about life should be the self-sustainment of a relevant system that is "defined" by its genetic information, the self-sustainment could not have arisen before the origin of Darwinian evolution, which was just marked by the emergence of genetic information. The logic behind the idea of the RNA world is not as tenable as it has been believed. That is, genetic molecules and functional molecules, even though not being the same material, could have emerged together in the beginning and launched the evolution-provided that the genetic molecules can "simply" code the functional molecules. However, due to these or those reasons, alternative scenarios are generally much less convincing than the RNA world. In particular, when considering the accumulating experimental evidence that is supporting a de novo origin of the RNA world, it seems now quite reasonable to believe that such a world may have just stood at the very beginning of life on the Earth. Therewith, we acquire a concrete scenario for our attempts to appreciate those fundamental issues that are involved in the origin of life. In the light of those possible scenes included in this scenario, Darwinian evolution may have originated at the molecular level, realized upon a functional RNA. When two or more functional RNAs emerged, for their efficient cooperation, there should have been a selective pressure for the emergence of protocells. But it was not until the appearance of the "unitary-protocell", which had all of its RNA genes linked into a chromosome, that Darwinian evolution made its full step towards the cellular level-no longer severely constrained by the low-grade evolution at the molecular level. Self-sustainment did not make sense before protocells emerged. The selection pressure that was favoring the exploration of more and more fundamental raw materials resulted in an evolutionary tendency of life to become more and more self-sustained. New functions for the entities to adapt to environments, including those that are involved in the self-sustainment per se, would bring new burdens to the self-sustainment-the advantage of these functions must overweigh the corresponding disadvantage.
The Indian Ocean Dipole (IOD) plays a crucial role in shaping local and global environments, yet its effects on interannual variability of the Arabian Sea oxygen minimum zone (ASOMZ) remains poorly ...understood. Here, we used a coupled physical‐biogeochemical model to investigate the dynamical response of the ASOMZ to extreme negative (2016) and positive (2019) IOD events. Our findings revealed that the suboxic area of the ASOMZ reduced (expanded) by ∼27% (∼28%) after the negative (positive) IOD event. Compared to the 2019 pIOD event, approximately 2.5 times more oxygen‐rich water was delivered into the Arabian Sea during the 2016 nIOD event, replenishing dissolved oxygen (DO) consumed by intensified upwelling‐induced enhanced remineralization of particulate organic matter (POM), thereby increasing the DO concentration in the Gulf of Aden. Conversely, more POM from the western Arabian Sea was transported to the central Arabian Sea, leading to a subsequent decrease in DO concentration there.
Plain Language Summary
The Indian Ocean Dipole (IOD) is a climate phenomenon that sea surface temperature in the western Indian Ocean becomes alternately warmer (positive phase) and then colder (negative phase) than the eastern Indian Ocean south of Indonesia. This variability significantly impacts global atmospheric circulation and environments. The Arabian Sea oxygen minimum zone (ASOMZ) is an area in the Arabian Sea characterized by low dissolved oxygen (DO) levels, which can have adverse effects on marine life. We used a model to examine how extreme IOD events influence the ASOMZ. The results suggested that during the negative IOD event in 2016, the suboxic area of the ASOMZ decreased by approximately 27%, while it expanded by approximately 28% during the positive IOD event in 2019. The response of the ASOMZ to IOD events in the Gulf of Aden was primarily modulated by physical factors, such as the Somali Coastal Current and local upwelling. On the other hand, the ASOMZ in the central Arabian Sea was regulated by a combination of biological and physical processes. These findings contributed to our understanding of the ASOMZ's response to IOD events, which is essential for studying the Arabian Sea's marine ecosystem.
Key Points
The response of the Arabian Sea oxygen minimum zone to the Indian Ocean Dipole events in the Gulf of Aden was modulated by physical factors
The Arabian Sea oxygen minimum zone in the central Arabian Sea was regulated by both biological and physical processes
The upper edge of the Arabian Sea oxygen minimum zone invaded the lower euphotic zone (100–200 m) under the impact of Indian Ocean Dipole events
A long-term increase in coccolith size over the Pleistocene has long been discovered in global oceans. Such a long-term and evolutionary change is expected to exert substantial impact on the carbon ...cycle as coccolithophores are one of the major components of marine carbonate counter pump (CCP). Here, we present coccolith morphological data as well as coccolith calcite export at Ocean Drilling Program Site 1143 in the South China Sea over the past 2 Myr. The results confirm the idea that Earth eccentricity controlled coccolith size diversity and calcite export production in tropical oceans in the Pleistocene. In addition, we consider a possible origin of the long-term increase in coccolith size as a result of increased oceanic alkalinity availability. As coccolithophores evolved simultaneously in global oceans, the increased coccolith calcification may have promoted global marine particulate inorganic carbon production, especially for the interglacial stages. Therefore, the enhanced coccolith-based CCP may account for a stepwise increase in interglacial CO2 levels over the middle Pleistocene. High CO2 levels at the onset of the interglacial stages may reduce the glaciation rate, thereby prolonging an entire interglacial-glacial cycle after the middle Pleistocene.
•Long-term increase in coccolith size can result from increased availability of oceanic alkalinity.•Long-term increase in coccolith size may promote global PIC production over the Pleistocene.•Increased coccolith calcification may account for a long-term interglacial CO2 change over the MPT.
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