Preliminary marine gravity field from HY-2A/GM altimeter data

HY-2 A(Haiyang-2 A),launched in 2011,is the first ocean dynamic environment satellite of China and is equipped with a radar altimeter as one of the primary payloads.HY-2 A shifted the drift orbit in March 2016 and has been accumulating geodetic mission(GM)data for more than three years with 168-day cycle.In this paper,we present the preliminary gravity field inverted by the HY-2 A/GM data from March 2016 to December 2017 near Taiwan(21°–26°N,119°–123°E).The gravity anomaly is computed by Inverse Vening Meinesz(IVM)formula with a onedimensional FFT method during remove-restore procedure with the EGM2008 gravity model as the reference field.For comparison,CryoSat-2 altimeter data are used to inverse the gravity field near Taiwan Island by the same method.Comparing with the gravity field derived from CryoSat-2,a good agreement between the two data sets is found.The global ocean gravity models and National Geophysical Data Center(NGDC)shipboard gravity data also are used to assess the performance of HY-2 A/GM data.The evaluations show that HY-2 A and CryoSat-2 are at the same level in terms of gravity field recovery and the HY-2 A/GM altimeter-derived gravity field has an accuracy of 2.922 mGal.Therefore,we can believe that HY-2 A will be a new reliable data source for marine gravity field inversion and has the potentiality to improve the accuracy and resolution of the global marine gravity field.

Transcriptional landscape of cotton roots in response to salt stress at single-cell resolution

Increasing soil salinization has led to severe reductions in plant yield and quality,and investigating the mo-lecular mechanism of salt stress response is therefore an urgent priority.In this study,we systematically analyzed the response of cotton roots to salt stress using single-cell transcriptomics technology;56281 high-quality cells were obtained from 5-day-old lateral root tips of Gossypium arboreum under natural growth conditions and different salt treatments.Ten cell types with an array of novel marker genes were identified and confirmed by in situ RNA hybridization,and pseudotime analysis of some specific cell types revealed their potential differentiation trajectories.Prominent changes in cell numbers under salt stress were observed for outer epidermal and inner endodermal cells,which were significantly enriched in response to stress,amide biosynthetic process,glutathione metabolism,and glycolysis/gluconeogenesis.Analysis of differentially expressed genes identified in multiple comparisons revealed other functional ag-gregations concentrated on plant-type primary cell wall biogenesis,defense response,phenylpropanoid biosynthesis,and metabolic pathways.Some candidate differentially expressed genes encoding transcrip-tion factors or associated with plant hormones also responsive to salt stress were identified,and the func-tion of Ga03G2153,annotated as auxin-responsive GH3.6,was confirmed by virus-induced gene silencing.The GaGH3.6-silenced plants showed a severe stress-susceptible phenotype,and physiological and biochemical measurements indicated that they suffered more significant oxidative damage.These results suggest that GaGH3.6 might participate in cotton salt tolerance by regulating redox processes.We thus construct a transcriptional atlas of salt-stressed cotton roots at single-cell resolution,enabling us to explore cellular heterogeneity and differentiation trajectories and providing valuable insights into the mo-lecular mechanisms that underlie plant stress tolerance.

融合注意力机制的红外小目标检测

随着图像中显著目标检测准确率的提高,如何提升小目标的检测精度逐渐成为人们关注的重点。现有的目标检测方法主要研究以可见光图像作为输入的通用目标检测问题,小目标检测领域的大部分方法主要针对可见光图像,面向红外图像的较少。红外小目标不含颜色信息,与常规目标尺度差别大,更加依赖上下文信息。针对这些问题,提出一种基于YOLOv5的红外小目标检测模型。在标准的YOLOv5模型基础上,为了有效结合目标周围的局部信息和整体特征中的全局信息,同时适应红外小目标的细微形态变化,提出了动态上下文信息提取模块,引入通道-细节注意力模块汇聚红外小目标的通道信息和细节信息,提高回归精度。考虑到网络卷积过程中细节特征丢失的问题,在保证模型特征尺度相对应的情况下,上采样新的特征尺度与浅层特征融合,以捕捉更多红外小目标细节信息,避免特征混叠。为了证明方法的有效性,在公开的红外数据集ITTD、IRSTD-1k和NUAA-SIRST上进行验证。实验结果表明:在ITTD数据集中所提方法的mAP值超过对比方法5.1%。对比YOLOv5s基准模型,mAP值提高了3.7%,在IRSTD-1k和NUAA-SIRST数据集中也展示出良好的检测效果,并对自身模型进行了消融实验。本文所提出的红外小目标检测模型对复杂场景下的红外小目标鲁棒性很好,有效地提高了小目标检测的精度,降低了小目标的漏检率。

Synthesis and photocatalytic activity of ZnO-Au_(25) nanocomposites

ZnO-Au_(25) nanocomposites were synthesized by doping Au_(25) nanoclusters into the porous Zn O nanospheres. It was notable that the ultrasmall Au_(25) nanoclusters possessed uniform sizes and fine dispersibility on the porous ZnO supports. A considerable correlation between the loading of Au_(25) nanoclusters and the photocatalytic activity was found. Compared with the pure ZnO nanospheres, the ZnO-Au_(25) nanocomposites exhibited more efficient photocatalytic activity in terms of degradation of Rhodamine B(RhB) in an aqueous solution. In addition, the possible photocatalytic mechanisms are discussed in this work. This strategy may be helpful for preparing other novel hybrid nanocomposites with well-defined structures and superior performances.

Impacts of land use and planning on island ecosystem service values: a case study of Dinghai District on Zhoushan Archipelago, China

Recently designated as a new special economic zone in China,Zhoushan Archipelago is going through a rapid land use change that is expected to have significant impacts on ecosystem services.However,there is no baseline of ecosystem service value(ESV)of the Zhoushan Archipelago up to date,making it impossible to assess any impacts of land use changes.In this study,we adopted the concept of“equivalent value per unit area of ecosystem services in China”and computed the ESV for 2006,2012,and 2020 of a representative district,Dinghai,on the Zhoushan Archipelago.We then analyzed the spatial and temporal patterns of land use changes and their impacts on ESV.The results indicated that the ESV of Dinghai District declined by 59.3 M Chinese yuan($9.5 M US dollars)from 2006 to 2012 and would further decrease by an additional 30.9 M yuan($5 M US dollars)by 2020 according to its planned land uses.These declines in ESV were primarily due to increases in buildup areas and losses in wetland,farmland,and water areas.The results imply that more attention should be paid to controlling urban growth and protecting coastal wetlands in order to preserve valuable ecosystem services of the Archipelago.

Seizures and epilepsy secondary to viral infection in the central nervous system

Viral infection in the central nervous system(CNS)is a common cause of seizures and epilepsy.Acute symptomatic seizures can occur in the context of almost all types of acute CNS viral infection.However,late unprovoked seizures and epilepsy may not be frequent after viral infection of the CNS.The incidence of seizures and epilepsy after CNS viral infection is mainly dependent on the brain region of infection.It remains to be determined whether treatment of CNS viral infection using antiepileptic drugs(AEDs)can prevent seizures and subsequent epilepsy in patients,particularly with regard to the timing,drug choice and dosage,and duration of AEDs.The postoperative outcome of seizures in patients with intractable epilepsy caused by viral encephalitis primarily depends on the epileptogenic zone.In addition,neuroinflammation is known to be widely involved in the generation of seizures during CNS viral infection,and the effects of anti-inflammatory therapies in preventing seizures and epilepsy secondary to CNS viral infection require further studies.In this review,we discuss the incidence,mechanisms,clinical management and prognosis of seizures and epilepsy secondary to CNS viral infection,and summarize common CNS viral infections that cause seizures and epilepsy.