近15 年黄土丘陵区退耕农户特征变化研究

退耕还林( 草) 工程是黄土高原生态治理的主要举措，为认识黄土丘陵区十几年来参与退耕的农 户特征变化，文中对2001 年退耕还林( 草) 工程试点初期陕西省安塞县的149 户调查农户进行了跟踪回访 ( 2015 年) ，对比分析了15 年来农户搬离情况、农户劳动力结构、耕地和养殖情况、家庭收入情况、退耕态度等 的变化特征。分析表明: 近15 年来，离开农村生活的农户增加，非农业劳动力比例和数量增加，非农业收入增 加很快，退耕农户表现出明显的向非农化转变特征，整体收入结构好转; 但退耕农户之间收入差异增加，农业 生产的专业化分工特征明显; 与初期相比，退耕农户的生态保护意识特征趋于淡化，对补贴款发放期限和强度 期望提高，停止补贴后有复耕意向的农户有所增加。</p

Population Dynamics of Several Species of Amphipods in the Macroalgae Canopies in Yudang Lagoon

研究了2007年11月至2008年5月期间筼筜湖大型海藻群落几种藻栖端足类的种群动态.结果显示,筼筜湖藻栖的端足类主要有:上野蜾蠃蜚(COrOPHIuM uEnOI)、日本大螯蜚(grAndIdIErEllA JAPOnICA)、强壮藻钩虾(A MPITHOE VAlI-dA)、平掌拟钩虾(grAMMArOPSIS lAEVIPAlMATA)和尖额麦秆虫(CAPrEllA PAnAnTIS).但不同时期、不同藻丛,端足类的种类组成和丰度存在差异.条浒苔(EnTErOMOrPHA ClATHrATA)主导的藻丛,主要出现在2007年11月至2008年1月,上野蜾蠃蜚和日本大螯蜚是丰度最高的两种端足类,它们在11月达到丰度的最大值,分别为3.22x104和1.07x104M-2.细基江蓠繁枝变种(grACIlArlA TEnuISTIPITATAVAr.lIuI)和根枝藻(rHIzOClOnIuMSP.)主导的藻丛分别出现在2008年1—3月和3—5月,上野蜾蠃蜚是其中最优势的端足类,但丰度较低.石莼(ulVA lACTuCA)主导的藻丛在整个调查期间都有分布,端足类以上野蜾蠃蜚和强壮藻钩虾为主,丰度在3月最高,分别为11.59x104和1.20x104M-2,而后迅速下降.不过,在石莼主导的藻丛,端足类的丰度和大型海藻生物量之间的变化并不同步,而是存在一个月的滞后,据推测,可能是由于大型海藻啃食者(如强壮藻钩虾)的滞后造成的.The population dynamics of several species of amphipods in the macroalgae canopies were studied from November 2007 to May 2008 in Yundang Lagoon.The results showed that amphipods in the canopies were mainly composed of Corophium uenoi,Grandidierella japonica,Ampithoe valida,Grammaropsis laevipalmata and Caprella panantis.However,the species composition and the abundance of amphipods varied in the canopies dominated by different species of macroalgae and in different seasons.In the canopy dominated by Enteromorpha clathrata,which appeared between November 2007 and January 2008,C.uenoi,G.japonica and C.panantis were dominant amphipods,whose abundance was highest in November 2007,up to 3.22×104,1.07 ×104and 0.56×104 m-2,respectively.In the canopies dominated by Gracilarla tenuistipitata var.liui and Rhizoclonium sp.,which appeared during January to March 2008 and March to May 2008,respectively,C.uenoi was the most dominant species,but its abundance was relatively low.In the canopy dominated by Ulva lactuca,C.uenoi,A.valida and G.laevipalmata dominated the amphipod community,with the maximum abundance(11.59×104,1.20×104and 0.56×104 m-2,respectively) in March,after which,the abundance sharply declined.The temporal pattern of amphipods′ abundance didn′t synchronize with that of macroalgal biomass in U.lactuca dominated canopy,with about one month lag for amphipods.厦门市科技重点项目(3502Z20102004

Measurement of integrated luminosity of data collected at 3.773 GeV by BESIII from 2021 to 2024

We present a measurement of the integrated luminosity e+e- of collision data collected by the BESIII detector at the BEPCII collider at a center-of-mass energy of Ecm = 3.773 GeV. The integrated luminosities of the datasets taken from December 2021 to June 2022, from November 2022 to June 2023, and from October 2023 to February 2024 were determined to be 4.995±0.019 fb-1, 8.157±0.031 fb-1, and 4.191±0.016 fb-1, respectively, by analyzing large angle Bhabha scattering events. The uncertainties are dominated by systematic effects, and the statistical uncertainties are negligible. Our results provide essential input for future analyses and precision measurements

Determination of the number of ψ(3686) events taken at BESIII

The number of ψ(3686) events collected by the BESIII detector during the 2021 run period is determined to be (2259.3±11.1)×106 by counting inclusive ψ(3686) hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of ψ(3686) events collected during the 2009 and 2012 run periods are updated to be (107.7±0.6)×106 and (345.4±2.6)×106, respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of ψ(3686) events in the three data samples is (2712.4±14.3)×10^