分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2024-04-10
摘要: Artificial Neural Network (ANN) has become a powerful tool in the field of scientific research with its powerful information encapsulation ability and convenient variational optimization method. In particular, there have been many recent advances in computational physics to solve variational problems. Deep neural network (DNN) is used to represent the wave function to solve quantum many-body problems using variational optimization. In this work we used a new Physics-Informed Neural Network (PINN) to represent the Cumulative Distribution Function (CDF) of some classical problems in quantum mechanics and to obtain their ground state wave function and ground state energy through the CDF. By benchmarking against the exact solution, the error of the results can be controlled at a very low level. This new network architecture and optimization method can provide a new choice for solving quantum many- body problems.
分类: 医学、药学 >> 临床医学 提交时间: 2023-10-09 合作期刊: 《中国全科医学》
摘要: The incidence of urinary retention during pregnancy is low which is mainly manifested as dysuria, frequent urination, incomplete urination, lower abdominal distension and abdominal pain and may induce severe complications and adverse pregnancy outcomes, so the early identification and treatment of urinary retention during pregnancy are crucial in clinical practice. Only by timely symptomatic and etiological treatment can the adverse outcome be avoided. This article made a review of the research progress of etiology, diagnosis and treatment, to provide diagnostic and therapeutic approaches and reference for clinical physicians.
分类: 生物学 >> 植物学 >> 植物生理学 提交时间: 2016-05-03
摘要: A better understanding of shade avoidance syndrome (SAS) is an urgent need because of its effect on energy reallocation. Leverage-related mechanism in crops is of potential economic interest for agricultural applications. Here we report the SAS phenotype at tissue level rice seedlings. Tissue-specific RNA-sequencing indicates auxin plays different roles between coleoptile and the first leaf. Phenotypes of wild type treated by gibberellin and brassinosteroid biosynthesis inhibitors and of related mutants suggest these two hormones positively regulate SAS. Our work reveals the diversity of hormone responses in different organs and different species in shade conditions.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: We present a method of near-infrared image reconstruction based on spatial modulation instability in a photorefractive strontium barium niobate crystal. The conditions that lead to the formation of modulation instability at near-infrared are discussed depending on the theory of modulation instability gain. Experimental results of scattered image reconstruction at the 1064 nm wavelength show the maximum cross-correlation coefficient and cross-correlation gain are 0.57 and 2.09 respectively. This method is expected to be an aid for near-infrared imaging technologies.
分类: 天文学 >> 恒星和银河系 提交时间: 2023-10-09
摘要: Symbiotic stars are interacting binary systems, making them valuable for studying various astronomical phenomena, such as stellar evolution, mass transfer, and accretion processes. Despite recent progress in the discovery of symbiotic stars, a significant discrepancy between the observed population of symbiotic stars and the number predicted by theoretical models. To bridge this gap, this study utilized machine learning techniques to efficiently identify new symbiotic stars candidates. Three algorithms (XGBoost, LightGBM, and Decision Tree) were applied to a dataset of 198 confirmed symbiotic stars and the resulting model was then used to analyze data from the LAMOST survey, leading to the identification of 11,709 potential symbiotic stars candidates. Out of the these potential symbiotic stars candidates listed in the catalog, 15 have spectra available in the SDSS survey. Among these 15 candidates, two candidates, namely V* V603 Ori and V* GN Tau, have been confirmed as symbiotic stars. The remaining 11 candidates have been classified as accreting-only symbiotic star candidates. The other two candidates, one of which has been identified as a galaxy by both SDSS and LAMOST surveys, and the other identified as a quasar by SDSS survey and as a galaxy by LAMOST survey.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: We revisit dark-matter production through freeze-in and freeze-out by solving the Boltzmann equations at the level of the phase-space distribution $f(p,t)$. Using the $2\to2$ annihilation and the $1\to2$ decay processes for illustration, we compare the resulting dark-matter relic abundance with that from the number-density approach. In the transition regime between freeze-in and freeze-out, we find the difference can be quite significant, or even by orders of magnitude if the annihilation of dark-matter particles or the decaying mediator is neglected. The freeze-in production in the $2\to2$ and the $1\to 2$ processes can also result in non-thermal phase-space distributions, or even multi-modal ones with out-of-equilibrium decay, which can potentially affect structure formation at late times. We also investigate how elastic scatterings can distort such non-thermal distributions.
分类: 生物学 >> 植物学 >> 植物生物化学、植物生物物理学 提交时间: 2016-05-03
摘要: Starch is the major component in maize kernels, providing a stable carbohydrate source for humans and livestock as well as raw material for the biofuel industry. Increasing maize kernel starch content will help meet industry demands and has the potential to increase overall yields. We developed a pair of maize near-isogenic lines (NILs) with different alleles for a starch quantitative trait locus on chromosome 3 (qHS3), resulting in different kernel starch content. To investigate the candidate genes for qHS3 and elucidate their effects on starch metabolism, RNA-Seq was performed for the developing kernels of the NILs at 14 and 21 d after pollination (DAP). Analysis of genomic and transcriptomic data identified 76 genes with nonsynonymous single nucleotide polymorphisms and 384 differentially expressed genes (DEGs) in the introgressed fragment, including a hexokinase gene, ZmHXK3a, which catalyzes the conversion of glucose to glucose-6-phosphate and may play a key role in starch metabolism. The expression pattern of all DEGs in starch metabolism shows that altered expression of the candidate genes for qHS3 promoted starch synthesis, with positive consequences for kernel starch content. These results expand the current understanding of starch biosynthesis and accumulation in maize kernels and provide potential candidate genes to increase starch content.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Anisotropy in electronic structures may ignite intriguing anisotropic optical responses, as has been well demonstrated in various systems including superconductors, semiconductors, and even topological Weyl semimetals. Meanwhile, it is well established in metal optics that the metal reflectance declines from one to zero when the photon frequency is above the plasma frequency {\omega}p , behaving as a plasma mirror. However, the exploration of anisotropic plasma mirrors and corresponding applications remains elusive, especially at room temperature. Here, we discover a pronounced anisotropic plasma reflectance edge in the type-II Weyl semimetal WP2, with an anisotropy ratio of {\omega}p up to 1.5. Such anisotropic plasma mirror behavior and its robustness against temperature promise optical device applications over a wide temperature range. For example, the high sensitivity of polarization-resolved plasma reflectance edge renders WP2 an inherent polarization detector. We further achieve a room-temperature WP2-based optical switch, effectively controlled by simply tuning the light polarization. These findings extend the frontiers of metal optics as a discipline and promise the design of multifunctional devices combining both topological and optical features.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: We present analysis of the spatial density structure for the outer disk from 8$-$14 \,kpc with the LAMOST DR5 13534 OB-type stars and observe similar flaring on north and south sides of the disk implying that the flaring structure is symmetrical about the Galactic plane, for which the scale height at different Galactocentric distance is from 0.14 to 0.5 \,kpc. By using the average slope to characterize the flaring strength we find that the thickness of the OB stellar disk is similar but flaring is slightly stronger compared to the thin disk as traced by red giant branch stars, possibly implying that secular evolution is not the main contributor to the flaring but perturbation scenarios such as interactions with passing dwarf galaxies should be more possible. When comparing the scale height of OB stellar disk of the north and south sides with the gas disk, the former one is slightly thicker than the later one by $\approx$ 33 and 9 \,pc, meaning that one could tentatively use young OB-type stars to trace the gas properties. Meanwhile, we unravel that the radial scale length of the young OB stellar disk is 1.17 $\pm$ 0.05 \,kpc, which is shorter than that of the gas disk, confirming that the gas disk is more extended than stellar disk. What is more, by considering the mid-plane displacements ($Z_{0}$) in our density model we find that almost all of $Z_{0}$ are within 100 \,pc with the increasing trend as Galactocentric distance increases.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Frequent accretion of external cold gas is thought to play an important role in galaxy assembly. However, almost all known kinematically misaligned galaxies identify only one gas disk that is misaligned with the stellar disk, implying a single gas acquisition event. Here we report a new configuration in two galaxies where both contain two gas disks misaligned with each other and also with the stellar disk. Such systems are not expected to be stable or long-lasting, challenging the traditional picture of gas accretion of galaxies and their angular momentum build-up. The differences in kinematic position angles are larger than 120{\deg} between the two gas disks, and 40{\deg} between each gas disk and the stellar component. The star formation activity is enhanced at the interface of the two gas disks compared with the other regions within the same galaxy. Such systems illustrate that low-redshift galaxies can still experience multiple gas acquisition events, and provide a new view into the origins of galactic gas.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Frequent accretion of external cold gas is thought to play an important role in galaxy assembly. However, almost all known kinematically misaligned galaxies identify only one gas disk that is misaligned with the stellar disk, implying a single gas acquisition event. Here we report a new configuration in two galaxies where both contain two gas disks misaligned with each other and also with the stellar disk. Such systems are not expected to be stable or long-lasting, challenging the traditional picture of gas accretion of galaxies and their angular momentum build-up. The differences in kinematic position angles are larger than 120{\deg} between the two gas disks, and 40{\deg} between each gas disk and the stellar component. The star formation activity is enhanced at the interface of the two gas disks compared with the other regions within the same galaxy. Such systems illustrate that low-redshift galaxies can still experience multiple gas acquisition events, and provide a new view into the origins of galactic gas.