Historical biogeography and evolutionary diversification of Lilium(Liliaceae): New insights from plastome phylogenomics

Here, we infer the historical biogeography and evolutionary diversification of the genus Lilium. For this purpose, we used the complete plastomes of 64 currently accepted species in the genus Lilium(14plastomes were newly sequenced) to recover the phylogenetic backbone of the genus and a timecalibrated phylogenetic framework to estimate biogeographical history scenarios and evolutionary diversification rates of Lilium. Our results suggest that ancient climatic changes and geological tectonic activities jointly shaped the distribution range and drove evolutionary radiation of Lilium, including the Middle Miocene Climate Optimum(MMCO), the late Miocene global cooling, as well as the successive uplift of the Qinghai-Tibet Plateau(QTP) and the strengthening of the monsoon climate in East Asia during the late Miocene and the Pliocene. This case study suggests that the unique geological and climatic events in the Neogene of East Asia, in particular the uplift of QTP and the enhancement of monsoonal climate, may have played an essential role in formation of uneven distribution of plant diversity in the Northern Hemisphere.

Why is the beautyberry so colourful? Evolution,biogeography,and diversification of fruit colours in Callicarpa(Lamiaceae)

Fruit colour is essential to seed dispersal,speciation,and biological diversity in global ecosystems.The relationship between fruit-colour variation and species diversification has long been of interest in evolutionary biology,but remains poorly understood at the genus level.Here,we used Callicarpa,a typical representative of pantropical angiosperm,to analyse whether fruit colours are correlated with biogeographic distribution,dispersal events,and diversification rate.We estimated a time-calibrated phylogeny for Callicarpa and reconstructed ancestral fruit colour.Utilizing phylogenetic methods,we estimated the major dispersal events across the phylogenetic tree and the most likely fruit colours related to each dispersal event,and tested whether the dispersal frequencies and distances of the four fruit colours between major biogeographical areas were equal.We then tested whether fruit colours are correlated with latitude,elevation,and diversification rate.Biogeographical reconstructions showed that Callicarpa originated in the East Asia and Southeast Asia during the Eocene(-35.53 Ma) and diverse species diverged mainly in the Miocene and lasted into the Pleistocene.Large-scale dispersal events were significantly associated with violet-fruited lineages.Furthermore,different fruit colours were markedly correlated with different latitudes and elevations(e.g.,violet fruits were correlated with higher latitudes and elevations;red fruits and black fruits with lower latitudes;white fruits with higher elevations).Notably,violet fruits were statistically associated with highest diversification rates,driving fruit colour variation among different regions globally.Our results contribute to further understanding why fruit colour is so variable at the genus level of angiosperms in different areas around the world.

Diversification evidence of bitcoin and gold from wavelet analysis

To measure the diversification capability of Bitcoin,this study employs wavelet analysis to investigate the coherence of Bitcoin price with the equity markets of both the emerging and developed economies,considering the COVID-19 pandemic and the recent Russia-Ukraine war.The results based on the data from January 9,2014 to May 31,2022 reveal that compared with gold,Bitcoin consistently provides diversification opportunities with all six representative market indices examined,specifically under the normal market condition.In particular,for short-term horizons,Bitcoin shows favorably low correlation with each index for all years,whereas exception is observed for gold.In addition,diversification between Bitcoin and gold is demonstrated as well,mainly for short-term investments.However,the diversification benefit is conditional for both Bitcoin and gold under the recent pandemic and war crises.The findings remind investors and portfolio managers planning to incorporate Bitcoin into their portfolios as a diversification tool to be aware of the global geopolitical conditions and other uncertainty in considering their investment tools and durations.

Cover Enhancement Method for Audio Steganography Based on Universal Adversarial Perturbations with Sample Diversification

Steganography techniques,such as audio steganography,have been widely used in covert communication.However,the deep neural network,especially the convolutional neural network(CNN),has greatly threatened the security of audio steganography.Besides,existing adversarial attacks-based countermeasures cannot provide general perturbation,and the trans-ferability against unknown steganography detection methods is weak.This paper proposes a cover enhancement method for audio steganography based on universal adversarial perturbations with sample diversification to address these issues.Universal adversarial perturbation is constructed by iteratively optimizing adversarial perturbation,which applies adversarial attack tech-niques,such as Deepfool.Moreover,the sample diversification strategy is designed to improve the transferability of adversarial perturbations in black-box attack scenarios,where two types of common audio-processing operations are considered,including noise addition and moving picture experts group audio layer III(MP3)compression.Furthermore,the perturbation ensemble method is applied to further improve the attacks’transferability by integrating perturbations of different detection networks with heterogeneous architec-tures.Consequently,the single universal adversarial perturbation can enhance different cover audios against a CNN-based detection network.Extensive experiments have been conducted,and the results demonstrate that the average missed-detection probabilities of the proposed method are higher than those of the state-of-the-art methods by 7.3%and 16.6%for known and unknown detection networks,respectively.It verifies the efficiency and transferability of the proposed methods for the cover enhancement of audio steganography.

Determinants of Household Choice of Livelihood Diversification Strategies in Selected Drought Prone Areas of the Southern Nations Nationalities and Peoples’ Region, Ethiopia

The study aimed at identifying the determinants of household’s choice of livelihood diversification strategies. The result of the study based on a total of 384 sample respondents selected using multistage sampling procedures. Furthermore the study employed bivariate Probit econometric model to identify factors affecting household’s choice of livelihood diversification strategies. The result of the descriptive statistics showed that households in the study area were engaged in four types of combination of livelihood diversification strategies: on-farm only, on-farm plus off-farm, on-farm plus non-farm, and on-farm plus off-farm plus non-farm with their respective share of 34.9, 11.5, 47.9 and 5.7 percent respectively. The econometric model result showed that wealth, sex, education level, livestok holding, and training were negatively and significantly determined households choice of off-farm livelihood strategies;whereas past erosion hazard and distance to market were positively and significantly determined their choice of off-farm livelihood strategies. On the other hand, wealth, dependency ratio, past erosion hazard, market availability, yield loss/reduction due to drought, distance to credit source, distance to market, frequency of extension contact, and ICT ownership (Radio, TV and/or Mobile phone) positively determine household’s choice of non-farm livelihood strategies whereas access to irrigation and distance to credit negatively determined their choice of non-farm livelihood strategies.

数字化变革背景下技术多元化对企业韧性的影响

基于资源基础理论,聚焦企业韧性的稳定性和灵活性特征,探讨数字化变革背景下技术多元化与企业韧性的关系。利用2018~2022年新冠疫情冲击前后中国上市高新技术企业的数据,采用OLS回归和生存分析法进行实证分析。结果表明:非相关技术多元化和相关技术多元化均与企业受到冲击后的稳定性呈倒U型关系;非相关技术多元化负向影响企业受到冲击后的灵活性,而相关技术多元化正向影响企业受到冲击后的灵活性;数字化变革加强了相关技术多元化与企业受到冲击后稳定性间的倒U型关系,并削弱了非相关技术多元化对企业受到冲击后灵活性的抑制作用。研究结论丰富和拓展了技术多元化与企业韧性的相关研究,为企业制定合适的技术多元化战略以增强韧性提供参考。

基于生计资本的农户可持续生计研究——以滇琼天然橡胶主产区为例

运用海南和云南橡胶主产区615个种植户的调查数据,测算了农户生计资本水平,设计了生计活动多样性指数和家庭收入多元化指数,通过多元线性回归模型和中介效应模型,探讨了生计资本配置对农户可持续生计的影响机制。研究发现:1)农户生计资本积累有助于丰富农户家庭生计活动和收入来源结构,尤其是金融资本积累有助于提升农户生计活动多样性水平;不同生计资本结构对农户生计结果的影响存在地域性差异;自然资本禀赋对海南产区的收入多元化水平有显著推动作用,但在云南产区却可能存在“诅咒”效应。2)地域差异、生产决策和农户特性对可持续生计有重要影响。村庄所处的海拔高、距县城距离远对农户开展多样化生计构成挑战;割胶生产规律固化虽然可能会削弱农户其他生产经营活动,但由于其劳动力调整灵活性强,可更好地稳定家庭收入;土地细碎化具有多元化生计的效果,但不一定有收入效应;虽然贫困户身份可帮助农户获得相关政策的支持,但增强生计能力才是实现可持续生计的关键所在。3)生计资本对生计活动和家庭收入的影响存在中介效应。生计资本对生计多样性的促进作用,有52.70%是通过提高生计资本统筹能力实现的,家庭就业策略优化有助于增强生计资本对收入多元化的促进作用,中介效应达30.52%。最后,建议通过提高农户家庭生计资本统筹能力、加强生计能力建设、扩展就业信息渠道等来增强农户生计综合能力。

中国制造业企业海外投资多元化对经营绩效的影响研究

中国制造业企业积极参与海外投资,是提升中国制造国际影响力和促进“双循环”发展格局的重要途径。采用中国制造业上市公司海外投资数据,实证考察企业海外直接投资的行业和地区分散度对其经营绩效的影响效应和作用机制。研究发现:第一,制造业上市公司海外投资行业或地区多元化程度的提高,均显著降低了企业经营绩效;第二,在非国有企业和高技术企业中,海外投资多元化程度的提高对企业经营绩效的负面影响表现更为显著;第三,经营成本上升和资源利用效率下降,是海外投资多元化导致企业经营绩效下降两条重要机制路径。研究结论可以从理性权衡企业多元化经营成本—收益、加大创新提升企业核心竞争力、政府出台产业政策引导投资风向着手改善制造业企业海外投资效率和合理性。

服务业产业多样化对城市经济韧性的影响——来自地级市夜间灯光数据的证据

本文利用夜间灯光栅格数据,测算了2008—2019年我国281个地级市的经济韧性,并研究了服务业产业多样化类型对城市经济韧性的影响。研究发现:服务业产业无关多样化程度越高的城市经济韧性相对越强,而相关多样化对城市经济韧性具有部分负向作用。多种检验表明上述结果稳健。不同城市规模和区域一体化程度的产业多样化与城市经济韧性关系具有一定区别,但总体上同质性大于异质性。利用中介效应检验进行作用机制分析后发现,服务业无关多样化可通过提高服务业就业水平和产出水平提高城市的经济韧性。因此,城市经济规划建设中应将提升经济韧性作为重要考虑因素,结合服务业产业多样化特征因地制宜,根据城市规模适度提高城市产业多样化。

非控股大股东退出威胁与多元化经营:抑制还是促进?

该文基于2007—2021年沪深两市A股上市公司的样本,检验了非控股大股东退出威胁对企业多元化经营的影响。研究发现:非控股大股东退出威胁发挥治理效应约束企业多元化扩张,主要作用机制是减少管理层在职消费和抑制控股股东掏空行为;异质性检验发现,当公司管理层持股、存在实际控制人、信息环境质量高及处于竞争性行业时,退出威胁对多元化的抑制作用更显著;拓展性检验发现非控股大股东退出威胁降低了企业非相关和相关多元化程度,且对非相关多元化的减少更显著,并提升了多元化经营价值。

银行分支机构准入管制放松影响企业多元化经营机理探讨——基于中国城市商业银行分支机构的实证检验

企业多元化经营受益于银行发放多元化经营所需资金贷款,受制于银行发挥债权人治理作用的外部监督。笔者基于资源基础理论和代理理论,以2004—2020年中国沪深A股上市公司为研究样本,结合城市商业银行分支机构数据,利用多元线性回归方法,实证检验了银行分支机构准入管制放松对企业多元化经营是否有影响以及影响的方式、方向和程度。检验结果证实:银行分支机构准入管制放松与企业多元化经营显著正相关;在银行分支机构准入管制放松正向影响企业多元化经营过程中,银行缓解企业融资约束和增加企业管理层攫取私利行为具有中介效应;企业聘请会计师事务所的审计质量和企业的内部控制质量发挥调节作用。本研究尝试性地将银行管制体制改革与企业多元化经营结合起来探究银行分支机构准入管制放松对企业多元化经营的影响机理,在一定程度上拓展了资源基础理论和代理理论的应用边界,丰富了银行管制和企业多元化经营的相关文献,研究结论能够为银行业体制改革和企业多元化经营提供理论依据。

技术多元化能够促进企业绩效提升吗--技术重组模式与科学知识搜索的调节作用

技术多元化是企业获取竞争优势的关键,对于其如何影响企业绩效这一问题,学界存在不同观点。解决跨领域技术融合难题是企业从技术多元化战略中获益的关键,然而现有文献忽略了不同企业技术重组搜索特征差异,对于如何优化技术重组搜索过程以提升技术多元化战略实施效果这一问题尚未提供答案。从技术重组搜索视角出发,探究企业技术重组模式、科学知识搜索对技术多元化与企业绩效关系的调节作用。基于我国高技术产业上市公司面板数据的实证研究发现:技术多元化与企业绩效呈倒U型关系;技术重组创造促使该倒U型关系曲线变得平坦,技术重组再利用促使该倒U型关系曲线变得陡峭;科学知识搜索强度的调节作用不显著,但在企业科学知识搜索强度较高且擅长技术重组创造的情况下,技术多元化与绩效正相关,从而将“技术多元化陷阱”转变为“技术多元化优势”。随着技术多元化程度加深,企业不仅可以通过积累资源,而且能够通过优化技术重组过程,由技术重组再利用模式向技术重组创造模式转变,并通过加强科学知识搜索运用从技术多元化战略中获益。

共同机构所有权与客户集中度

高客户集中度加大了公司经营风险和供需链断裂可能性,这显然不利于“国内国际双循环”发展格局的构建。本文利用2007-2021年中国上市公司数据,从理论和实证上分析了共同机构所有权对公司客户集中度的影响。研究发现,共同机构所有权通过提高公司议价能力和信息透明度来降低过高客户集中度,且其联结程度越高、联盟数量越多,降低效果越明显。进一步分析发现,当企业主要客户出现业绩下滑或经营不善时,共同机构所有权才会发挥协同监督效应以干预企业客户集中度,且该效应的发挥在西部地区公司和非高新技术公司中更显著。本文为降低企业对单一大客户依赖程度、加强政府相关部门在企业客户资源配置优化管理方面的作用提供了政策启示。

提升基础能力和动态能力,实现学会差异化发展——以工科学会为例

学会发展路径可以大致分为交流路径、智库路径、科普路径、产学融合路径和综合发展路径。同一学科的不同学会,其发展路径具有差异性。学会的基础能力和动态能力对工科学会发展路径差异化具有重要影响。课题组考察中外5家知名工科学会后发现,在基础能力方面,规范管理能力决定着学会发展的健康有序程度,资源管理能力决定学会初创和发展阶段的路径选择。在动态能力方面,学会的感知能力决定了学会改革创新的意识和效能,学会的资源获取能力决定学会内生资源的丰富程度。学会的基础能力和动态能力能够互相转换,从而提升学会的可持续发展能力。为此,基于学会在不同阶段具备的能力差异,建议学会立足自身发展阶段,甄别特定情境选择不同发展路径,梳理与整合资源,夯实基础能力,树立动态能力理念,突破路径依赖实现高质量发展。

贸易便利化、制造业出口多样化与出口产品质量

贸易便利化缓解了复杂的通关程序、难以统一的海关系统等贸易壁垒困境,给制造业出口产品带来了“质”的提高的可能性,在此背景下,探讨贸易便利化对制造业出口产品质量的影响,同时纳入制造业出口多样化作为调节变量,利用2011—2021年省际面板数据进行固定效应实证检验。结果显示:贸易便利化整体上显著促进制造业出口产品质量的提高,该促进效应中,口岸效率>营商环境>基础设施>电子商务;不同区域内贸易便利化对制造业出口产品质量有不同的影响,其中,东部地区经济发达,具有显著促进作用,西部地区可能由于过度竞争的原因,对制造业出口产品质量有抑制的作用;制造业出口多样化在贸易便利化驱动过程中发挥显著正向调节作用。

产业多样化与城市经济韧性——三阶段模型与创业活力的调节作用

如何最大限度降低不确定性风险带来的负面影响,增强城市经济韧性,是我国经济由高速增长阶段转向高质量发展阶段面临的重要问题。基于自组织理论,文章以2004—2020年中国282个地级市为样本,创新性地提出产业多样化影响城市经济韧性的三阶段模型,从协调成本效应、知识溢出效应和突破性创新效应等角度出发,探究产业多样化与城市经济韧性的关系以及创业活力的调节作用。结果表明:产业多样化影响城市经济韧性满足三阶段模型的假设,两者存在N型曲线关系,创业活力对城市经济韧性具有正向影响,创业活力负向调节产业多样化与城市经济韧性的N型关系;基于产业相关度的回归发现,相关多样化与城市经济韧性呈现倒U型关系,无关多样化与城市经济韧性呈现U型关系;基于区域异质性的回归发现,产业多样化与城市经济韧性的N型关系在东部地区、沿海城市显著,而在中西部地区和内陆城市不显著。研究提出,地方政府应根据不同产业阶段化变化的特征,灵活调节产业政策,促进产业间协调发展,增强产业多样化对城市经济韧性的积极作用。

欧洲汽车动力系统多元化的发展趋势和展望

当前,全球能源结构处在变革时期,低碳和零碳化是包括汽车行业在内的所有经济运行和规划活动中的重中之重。汽车动力系统的能源呈现多元化的发展趋势,始于轻型车的电动化已成为不可逆转的总体方向,而氢时代在到来之前面临各种技术和非技术类等诸多问题的挑战。电动化带来的一个更为广泛应用的新技术是人工智能(AI),从而使得汽车动力系统逐步突破传统设计方法的局限得以适应更加复杂的环境条件并获得高效率。该文介绍欧洲汽车动力系统电动化和多元化的发展趋势,针对欧盟正在考虑中的电力合成燃料等问题并结合动力系统智能化等发展趋势,对欧洲汽车技术领域在2035年前的研发动向作出相关思考以及展望。

对中国艺术歌曲音乐风格的重识

面对中国艺术歌曲音乐风格日趋单一的现实,我们理应继续追随先贤的脚步,学习他们包容、创新的精神,学习他们虚怀若谷的态度和思维,学习他们科学的理念和方法,去重新挖掘艺术歌曲的价值,从中汲取经验和灵感,使中国艺术歌曲发展更加多元、系统。作为歌者也要肩负起责任和义务,在二度创作中准确、完美地诠释和表现中国艺术歌曲的审美风格,这样才能使中国艺术歌曲复归多元化的发展态势,更加成熟,更加完善。

金融高质量发展助力强国建设背景下巨灾商业保险发展研究——基于粤港澳大湾区实践

推进保险业创新发展是深化金融供给侧结构性改革的重要部分,对加快建设中国特色现代金融体系、提高金融服务经济社会发展的质效具有重要意义。从粤港澳大湾区的实践来看,巨灾商业保险发展可以降低灾害风险对经济的影响,提升社会的整体巨灾应对能力,促进区域内跨境商业活动的顺利开展。文章解析了粤港澳大湾区巨灾商业保险的发展背景、制度设计和金融服务支持现状,深入分析了当前粤港澳大湾区巨灾商业保险发展中存在的个体覆盖问题、市场供给约束及法律保障制度缺陷,结合日、美三大著名湾区巨灾商业保险的发展经验,围绕金融高质量发展,从需求侧出发刺激巨灾保险需求、从供给侧出发释放巨灾保险活力、发挥政府职能推进高质量巨灾商业保险制度设计、探索中国特色的“多层次”巨灾商业保险制度四个方面,提出适合我国国情的巨灾商业保险发展的建议。

数字素养的农户收入增长效应研究

作为数字时代重要的新型人力资本,数字素养成为农户生计资本的重要组成部分。数字素养的提升使农户能够更好地应用先进技术、获取市场信息、拓展销售渠道、增加非农就业创业机会,从而产生显著的收入增长效应。采用“中国乡村振兴综合调查”(CRRS)2020年的数据,从数字设备操作、数字资源获取、数字技术应用、数字意识4个维度选取18项指标评价样本数字素养,实证检验数字素养对农户收入的影响,结果发现:农户数字素养提升能够显著增加其人均农业收入、人均非农收入和人均总收入,该收入增长效应对流动性约束较强的农户和非城郊村的农户更为显著;数字素养可以通过提高农业劳动生产率的路径增加农户农业收入,也可以通过促进家庭生计多样化的路径增加农户非农收入。因此,数字素养不仅具有显著的农户增收效应,而且有助于长尾群体共享数字红利,应在加强和普及数字素养教育的同时,重点帮扶数字弱势群体以缩小数字鸿沟,并切实提高农业劳动生产率和促进农户生计多样化,充分发挥数字素养的农户增收效应。