摘要：Aims Bee-pollinated flowers are rarely red,presumably because bees(which lack red receptors)have difficulty detecting red *** the response of bees to red colour has been investigated in lab experiments,most stimuli have been pure red,while the subtle diversity of red as perceived by humans(human-red)has received very limited *** we test the hypothesis that ultraviolet(UV)reflected from human-red flowers enhances their attractiveness to bees,through increased chromatic *** Using Onosma confertum(Boraginaceae),a plant with UV-reflecting red flowers that are pollinated by bumblebees,we investigated the effects of UV reflection on pollinator responses by conducting phenotypic manipulation experiments in the *** preferences of flower-naïve bumblebees were also *** perception by bumblebees was estimated in terms of chromatic and achromatic contrast,based on two different colour perception *** Findings We found that both natural and flower-naïve bumblebees strongly preferred visiting UV-reflecting targets compared with UV-absorbing *** models show that the UV-reflecting flowers exhibit higher spectral purity and higher chromatic contrast against the foliage background,whereas they have similar achromatic contrast in terms of green receptor *** results indicate that the component of UV reflection increases chromatic contrast in ***,enhancing the visual attractiveness of these red flowers to *** further infer that the secondary reflectance might be a necessary component in human-red flowers that are primarily pollinated by animals without red receptors,such as bees.

摘要：Though several theoretical models have been proposed to design electronic flat-bands, the definite experimental realization in two-dimensional atomic crystal is still lacking. Here we propose a novel and realistic flat-band model based on threefold degenerate p-orbitals in two-dimensional ionic materials. Our theoretical analysis and first-principles calculations show that the proposed flat-band can be realized in 1 T layered materials of alkali-metal chalogenides and metal-carbon group compounds. Some of the former are theoretically predicted to be stable as layered materials(e.g., K2 S), and some of the latter have been experimentally fabricated in previous works(e.g., Gd2 CCl2). More interestingly, the flat-band is partially filled in the heterostructure of a K2 S monolayer and graphene layers. The spin polarized nearly flatband can be realized in the ferromagnetic state of a Gd2 CCl2 monolayer, which has been fabricated in experiments. Our theoretical model together with the material predictions provide a realistic platform for the study of flat-bands and related exotic quantum phases.

摘要：本研究在分析有关城市拆迁补偿理论和实践的基础上,构建基于利益平衡的拆迁补偿原则与定价机制和制度架构。认为,化解因分配和交换之利益失衡引起的拆迁冲突,利益均衡是理论基础,建构起合理的补偿定价机制及其运行保障制度是重点;城市拆迁补偿费的定价依据是足以使被拆迁人维持甚至提高与原有房屋直接相关的物质和精神生活水平,基本构成是被拆迁房屋建筑部分的市场价值和同等占用比例的土地使用权价值。

摘要：Rapid advances in DNA synthesis techniques have allowed the assembly and engineering of viral and microbial *** eukaryotic organisms,with their larger genomes,abundant transposons,and prevalent epigenetic regulation,present a new frontier to synthetic *** synthetic genomics have long been proposed,and exciting progress has been made using the top-down *** this perspective,we propose applying bottom-up genome synthesis in multicellular plants,starting from the model moss Physcomitrium patens,in which homologous recombination,DNA delivery,and regeneration are possible,although further optimizations are *** then discuss technical barriers,including genome assembly and plant transformation,associated with synthetic genomics in seed plants.

摘要：一般情况下,每年冬季是季节性流感高发季节,但在当前2019冠状病毒病(COVID-19)大流行期间,全球季节性流感活动呈“断崖式”下降。为应对即将到来的流感季节,亟需弄清这种前所未有的流感低水平流行的原因。本文中,我们探索了一种国家特异性推理模型,利用该模型估计中国、英国和美国这三个国家中佩戴口罩、人员流动变化(国际和国内)以及严重急性呼吸综合征冠状病毒2型(SARS-CoV-2)干扰的影响。结果发现,在这些地区增加一周佩戴口罩的干预措施,流感活动可减少11.3%~35.2%。实施一周的限制人员流动措施对国际(1.7%~6.5%)和国内社区(1.6%~2.8%)的影响较小。2020年至2021年,仅佩戴口罩这一项干预措施就可使阳性率下降13.3%至19.8%。仅人员流动变化可使阳性率降低5.2%至14.0%,其中79.8%~98.2%归因于国际旅行限制。SARS-CoV-2干扰仅在2019年至2020年具有统计学显著效应。中国北方地区及英国的阳性百分比分别降低7.6%(2.4~14.4)和10.2%(7.2~13.6)。探索所得出的结果对了解非药物干预措施和其他呼吸系统疾病背景下的流感演变有一定意义,有助于制定卫生政策,并可为公共卫生措施的个性化设计提供信息。

摘要：Confined low dimensional charges with high density such as two-dimensional electron gas(2 DEG)at interfaces and charged domain walls in ferroelectrics show great potential to serve as functional elements in future ***,stabilization and control of low dimensional charges is challenging,as they are usually subject to enormous depolarization ***,we demonstrate a method to fabricate tunable charged interfaces with~77°,86°and 94°head-to-head polarization configurations in multiferroic Bi Fe O_(3) thin films by grain boundary *** adjacent grains are cohesively bonded and the boundary is about 1 nm in width and devoid of any amorphous ***,the polarization remains almost unchanged near the grain boundaries,indicating the polarization charges are well compensated,i.e.,there should be two-dimensional charge gas confined at grain *** the tilt angle of the grain boundaries enables tuning the angle of polarization configurations from 71°to 109°,which in turn allows the control of charge density at the grain *** general and feasible method opens new doors for the application of charged interfaces in next generation nanoelectronics.