The Impacts and Causes of Land Fragmentation on Farm Productivity: Case Review of East African Countries

This report provides an overall assessment of land fragmentation problems in East Africa. Many parts of East Africa have become highly fragmented, putting development systems and activities in these areas at risk of complete collapse. Land fragmentation occurs when land gets converted for agriculture, industrialization, or urbanization, invaded by non-local plants, or enclosed for individual use and by subdividing farmlands into subsequent smaller units called parcels with varying average farm sizes. Fragmentation results from inappropriate agricultural development processes and ineffective land use planning that fails to recognize how farmland is used, and the importance of its interconnected areas. Insecurity of tenure and resource rights are key factors in making this possible. Land fragmentation is one of the key reasons why the ability of most resources in East Africa becomes scarcer, and those remaining become “privatized” by more powerful community members—keen to maintain their access to them. Such individualistic attitudes are new and disadvantage the poorest even further by affecting the traditional customary safety nets and agricultural outputs. Neither the government nor customary governance systems effectively protect resource access for the poorest. This review summary report identifies the key causes, measures, and implications, government interventions, and the common remedies to land fragmentation problems in the East African Countries of Kenya, Uganda, Rwanda, and Tanzania including neighboring Ethiopia, and the Sudan. The findings indicated from 2005 to 2015, the population kept increasing for all the named countries in East Africa with Rwanda and Uganda having a substantial increase in population density. The study review further explores the trend in the performance of agriculture by average farm sizes within the intervals of five years by highlighting their strong linkages and found that the average farm size has declined drastically, especially for Kenya. This can only mean that small farms kept becoming smaller and smaller and that there were more small-scale farmers. The results further depicted that the major and commonly cultivated food crops among the East African countries include maize, sorghum, rice, cassava, sweet potatoes, bananas, Irish potatoes, beans, peas, etc., with maize yields (Mt/ha) in 2003 for Uganda being the highest (1.79 Mt/ha) and the lowest in Rwanda (0.77 Mt/ha) respectively. Therefore, from the review results, recommendations are being made as to how the negative impacts of land fragmentation on agricultural productivity can be reduced or mitigated. One way is by community sensitization and awareness about the importance of land consolidation and its proposition on farm productivity.

Production of neutron-rich exotic nuclei in projectile fragmentation at Fermi energies

Isotopic fragment yields of projectile fragmentation in peripheral collisions of^(86)Kr on^(124;112)Sn and the mean neutron-to-proton ratios of the fragments are calculated, theoretically, within the ensemble approach of statistical multifragmentation model. Obtained data are compared to the experimental cross-section measurements for the projectile-like fragmentation in the reaction of 25 Me V/nucleon^(86)Kr+^(124;112)Sn at Texas A&M University.We show the enhancement in the production of neutronrich isotopes close to the projectile as observed in the experiments. We also demonstrate the universality of the limitation of the excitation energy induced in the projectile residues.

Energy Dependence of String Fragmentation Function and Ф Meson Production

The Ф meson productions in Au+Au and/or Pb+Pb collisions at AGS, SPS, RHIC, and LHC energies have been studied systematically with a hadron and string cascade model LUCIAE. After considering the energy dependence of the model parameter α in string fragmentation funetion and adjusting it to the expcrimenta! data of charged multiplicity to a certain extent, the model predictions for Ф meson yield, rapidity, and transverse mass distributions are compatible with the experimental data at AGS, SPS and RHIC energies. A calculation for Pb+Pb collisions at LHC energy is given as well. The obtained fractional variable in string fragmentation function shows a saturation in energy dependence. It is discussed that the saturation of fractional variable in string fragmentation function might be a qualitative representation of the energy dependence of nuclear transparency.

A Model Comparison Study of Fragment Production in 140 A MeV 58,64Ni+9Be Reactions

The cross sections of fragments produced in the 140 A MeV58,64Ni＋9 Be projectile fragmentation reactions are calculated by using the antisymmetrized molecular dynamics （AMD） model, the modified statistical abrasion- ablation （SAA） model, and the empirical EPAX2/EPAX3 formulae. The Gogny-gO interaction is taken as the effective nucleon-nucleon interaction in the AMD calculation, and the decays of fragments obtained from the AMD results are calculated by using the GEMINI code. The calculated cross sections of fragments are compared.

Bacterial Groups Concerned with Maturing Process in Manure Production Analyzed by a Method Based on Restriction Fragment Length Polymorphism Analysis

Composting is a biological aerobic decomposition process consisted from different phases. Although the Japanese Standards for manure recommended that it took at least 6 months to complete the maturing phase, there was no reliable ground. In order to find out shortening method of the maturing phase, the microorganisms concerned with a progress of the maturing was determined by using the most probable number method (MPN) and PCR-RFLP of the 16S rDNA, which was found effective to provide numbers and taxonomy of polymyxin B resistant bacterial groups in the former paper [1]. Compared to the numbers after thermophilic phase, those of Actinobacteria, δ-proteobacteria, and the other gram negative bacteria increased to 50 times, 20 times, and 105 times, respectively, after maturing phase, while those of Bacillus spp., and α and β-proteobacteria decreased to 1/10, and 1/105 after maturing phase. Numbers of the other Fumicutes, and γ-proteobacteria remained in the same revel. Actinobacteria, δ-proteobacteria, and the other gram negative bacteria might be concerned with a progress of the maturing phase, because these bacterial groups were detected and enumerated due to their proliferation ability. Although number of Acitinobacteria might be underestimated because of a PCR bias, the method was found effective for the purpose to monitor bacteria actively proliferated in culture medium.

A system-wide approach to minimize the operational cost of bench production in open-cast mining operations

The production cycle of open-cast coal mines generally in eludes drilling, blasting, loading, hauling and coal preparation activities. Individual optimization of these activities does not mean that the whole system is optimized. This paper proposes a cost model considering all activities in mining cycle and system-wide approach to minimize the total mining cost of bench production. Since the fragmentation size and blast-hole diameter are linked to all activities of mining system, they are considered as decision variables in the problem form ul at io n. The operatio n costs are then minimized by using the evolutionary algorithm. Moreover, the impact of the change in the explosive price, and the hourly unit cost of equipment on total mining cost is quantified by sensitivity analysis. A case study is implemented to demonstrate the developed model.

IMF production and symmetry energy in heavy ion collisions near Fermi energy

The symmetry energy at the time of the production of intermediate mass fragments(IMFs) is studied using experimentally observed IMF multiplicities combined with quantum statistical model calculations(QSM of Hahn and St cker).The ratios of difference in chemical potentials between neutrons and protons relative to the temperature,(μn-μp)/T,and the double ratio temperature,T,were extracted experimentally in the reactions of64,70Zn,64Ni+58,64Ni,112,124Sn,197Au,232Th at 40A MeV.The extracted(μn-μp)/TTscales linearly with δNN,where δNN is the asymmetry parameter,(N-Z)/A,of the emitting source and(μn-μp)/T=(11.1 1.4)δNN0.21 was derived.The experimentally extracted(μn-μp)/T and the double ratio temperatures are compared with those from the QSM calculations.The temperatures-,T,and densities,ρ,extracted from the(μn-μp)/T values agreed with those from the double ratio thermometer which used the yield ratios of d,t,h and α particles.However the two analyses of the differential chemical potential analysis and the initial temperature analysis end up almost identical relation between T and ρ.T=5.25±0.75 MeV is evaluated from the(μn-μp)/Tanalysis,but no density determination was possible.From the extracted T value,the symmetry energy coefficient Esym =14.6±3.5 MeV is determined for the emitting source of T=5.25±0.75 MeV.

权力、资本的碎化与尺度修复:城镇开发边界的政治经济学解释

文章从权力、资本与空间互动的视角审视中国城市增长主义下的空间增长逻辑,为城镇开发边界划定提供理论认知与实践建议。研究发现:(1)央地间的用途管制冲突、市辖区间的经济发展机会争夺造成规划增量空间大规模碎片状分散;(2)资本再地域化的空间需求与城镇开发边界的空间供给错配,资本避险引发空间治理危机;(3)城镇开发边界通过尺度上移、尺度外移的方式实现资本积累的尺度修复。文章从政治经济学视角理解城市空间增长内在逻辑与城镇开发边界的内涵,对城镇开发边界的划定具有重要理论与实践价值。

农户分化对农业生产托管的影响

发展农业生产托管是农业应对“刘易斯拐点”和人口红利消失的必然选择。基于江汉平原稻农的调研数据,使用Probit模型、CMP模型等分析农户分化对农业生产托管的影响,探讨农户分化对不同托管环节以及不同农户的异质性影响。研究表明:农户分化催生农业生产托管;农户分化对整地和收割环节等劳动密集型生产环节托管的作用显著,对育秧移栽和施肥与病虫害防治等技术密集型生产环节托管的作用不显著;农户分化对促进女性参与农业生产托管显著,对男性不显著;农户分化对高龄和低龄农户参与农业生产托管均显著,且通过1%的显著性检验,但对低龄农户的影响更大。据此,应进一步促进农业生产托管的发展与完善以应对农户分化;秉持“补弱扶强”原则,对于不同类型的生产环节托管的补贴激励政策有所侧重;提升农户生产托管意愿,以促进农业生产托管的发展与完善。

土地细碎化会抑制农户绿色生产行为吗?——现实背景、理论逻辑与实证检验

研究目的:从土地细碎化的现实情景出发,基于2021年江西省“百村千户”调查数据,分析土地细碎化对农户绿色生产行为的影响机理,并探讨生计策略的中介效应及要素禀赋的调节效应。研究方法:OLS,门槛效应模型,中介效应模型,调节效应模型。研究结果:(1)土地细碎化总体上抑制农户绿色生产行为采纳,但不同细碎化程度对农户绿色生产行为的影响效果存在差异,表现为土地细碎化程度的门槛效应,并与农户绿色生产行为基本呈倒U型关系。随着土地细碎化程度的提高,农户绿色生产行为先上升后下降。(2)土地细碎化通过影响农户的生计策略作用于其绿色生产行为选择。(3)要素禀赋正向调节土地细碎化对农户绿色生产行为的影响。(4)土地细碎化对农户不同绿色生产行为的影响存在代际差异性。研究结论:土地细碎化并非简单地抑制农户绿色生产行为,在有序推进土地细碎化治理工作的同时,应整合资源,优化配置,降低农户绿色生产行为采纳的禀赋约束,助力农业可持续发展的实现。

湖山露天铀矿多排孔大区块压渣爆破效果评价

为改善湖山铀矿爆破位移大、矿岩大块率高和前部铲装效率低等问题,湖山铀矿设计并开展了5个大区块压渣爆破试验,每个区块量为36~53万t,炮孔排数15~21排,自由面预留5~40 m宽的渣体,测定和统计了试验区块爆堆形态、装载效率、爆破块度以及底板标高偏差等指标,并与同期清渣爆破区块进行对比分析。结果表明:在爆炸冲击作用下,爆堆存在前扑及隆起现象,爆堆表面呈高低不等连续分布状态,爆堆不同部位最大增高变化范围为4.06~5.85 m;铲装效率方面,液压铲在压渣爆破区块的平均装载效率为2722 t/h,比同期清渣爆破区块平均值高4.69%;爆破块度方面,压渣爆破区块爆后块度分布优于清渣爆破区块,在控制大块率方面更有优势。此外,压渣爆破在底板标高控制方面有一定优势。该研究首次将压渣爆破技术推广至多排孔大区块(15~21排)爆破中,这既符合大型露天矿山生产的客观需求,也是设备大型化后的必然趋势。可以使得湖山铀矿爆破更为精细化的同时,也可以为国内外类似的矿山爆破提供重要的现场数据。

从行政主导到政社共同生产:城市社区微更新的逻辑转换与实现路径

随着城市社区微更新作为一种城市存量空间再生产模式的重要性愈发凸显,有必要探究其有效发挥作用的内在机理。深入考察上海市Z街道城市社区微更新的实践可见,由于基层政府服务项目的“碎片化”、社区的治理超载以及对民众主体性地位的遮蔽,行政主导下的城市社区微更新面临困境。在政绩逻辑驱动、运作困境推动和专家介入催化的综合作用下,城市基层政府通过充分动员社区民众参与、表达需求并进行整合,再加上政府内部的部门协同和流程再造,一种政社共同生产的城市社区治理模式亦逐渐生成。政社共同生产模式下的社区微更新,不仅能够切实满足社区居民的真实需求,还能够动员和激发社区民众的主体性以及参与社区治理的内在动力,更是重构了政府与社会关系。

耕地细碎化对农户种植业收入的影响——“非粮化”和耕地流转率的调节效应

耕地细碎化会导致农户种植活动的分散化,减少了农户的有效劳动时间,并阻碍了机械化作业的开展,不利于种植业的增产增收。采用“全国农村固定观察点调查”2009—2020年的面板数据,以种植主导型农户为研究样本,分析发现:农户的耕地细碎化程度提高对其种植业收入具有显著的负向影响,该结论在经过一系列稳健性检验和内生性处理后依然成立;家庭种植结构“非粮化”和村庄耕地流转率提高可以显著弱化耕地细碎化对农户种植业收入增长的抑制作用;相对而言,耕地细碎化对化肥施用强度较高农户、老龄化程度较高农户、丘陵山区农户的种植业收入具有更强的负向影响。因此,应促进耕地流转市场发育,加强农村土地整治,提高粮食生产比较收益,推动化肥农药使用减量增效,拓展优化农业社会化服务,在降低农户耕地细碎化程度的同时,有效缓解耕地细碎化对农民收入增长的抑制作用。

Isotopic production cross sections of fragmentation residues produced by ^(18)O ions on a carbon target near 260 MeV/nucleon

The isotopic cross sections of residual nuclei produced in fragmentation reactions of ^(18)O projectiles impinging on a carbon target at energies near 260 MeV/nucleon were measured at the HIRFL facility in Lanzhou(China).A full identification of atomic and mass numbers of fragments was achieved from the determination of their magnetic rigidity,energy loss,and time of flight.The production cross sections for a dozen of nitrogen,carbon,and boron isotopes were determined with uncertainties below 30% for most of the cases.The obtained cross sections for N and B isotopes show a rather good agreement with previous experimental data obtained with different projectile energies.The cross sections for some C isotopes seem to exhibit a dependence on the projectile energy.A comparison of the data and several theoretical model calculations are presented.

针对防疫人员碎片化睡眠的健康助眠产品设计策略研究

针对防疫人员碎片化睡眠面临的问题和困扰,提出相应设计策略,为设计实践提供理论指导。采用文献调研法、问卷调研法、数据分析法等,对防疫人员睡眠现状和现有产品进行调研分析,提出针对防疫人员碎片化睡眠的产品设计要素,确定防疫人员碎片化睡眠具体需求及产品设计走向。以自隔离式健康助眠枕为例,提出了具体设计策略,策略包含人机结构、人文情感价值及结合用户体验的产品设计目标。针对防疫人员碎片化睡眠的产品设计策略研究针对性强,指向明确,能够满足防疫人员的相关睡眠需求,改善其睡眠质量。

碎片化时代文化创意人才的数字素养培养研究

数字信息技术的进步改变了传统文化创意产业的生产方式和消费模式,整个文创产业的业态发生了数字化变革,文化产品的生产、传播、消费开始变得碎片化。数字化带来的碎片化,需要文创从业者具备更加全面的数字素养,其中包括整合碎片化资源的能力、融合碎片化传播的能力、精准满足碎片化需求的能力等。传统的文创人才培养机制已经不能满足文创产业发展对人才的新需求。所以,需要将数字素养培养融入文化创意专业的人才培养过程,通过专业内部优化协同融合、专业之间跨学科联合、校企间产教融合等举措,优化原有的人才培养机制,全面提升未来文化创意产业从业者的数字素养。

流通业数字化投入与国内价值链分工深度

在数字经济时代,信息通信技术向传统商贸流通业的深度赋能已然成为新发展格局背景下推动经济实现高质量、高效率发展的重要抓手。基于2002年、2007年、2012年和2017年的中国多区域投入产出表,实证检验流通业数字化投入对国内价值链分工深度的影响,并基于“质量”和“效率”双重视角考虑了国内市场条件在其间的互补性作用。研究发现:(1)流通业数字化投入水平提升有助于推动国内价值链分工深化。进一步从具体作用机制来看,国内价值链分工深度的提升主要通过规模经济效应和交易成本节约效应两条渠道实现。(2)异质性检验结果提示,在物流业、经济发展水平较高地区、竞争优势较低行业、省际数字化投入偏好性较强的样本中,流通业数字化投入对国内价值链分工深度的促进效应更为突出。(3)从“质量”和“效率”双重维度改善国内市场条件,能够“放大”流通业数字化投入对国内价值链分工的正向影响。因此,加大数据要素在流通中的渗透力度,在更广、更宽、更远的空间范围内进行媒介交换,是有效推进国内价值链分工深度提升的关键路径。

数字经济时代的刑事安全风险及其刑法防控体系

数字经济是经济发展的数字化形态,呈现平台化、链条化和无区域化等特点。人工智能、区块链、大数据等技术与经济发展的融合发展,不仅导致传统犯罪呈现数字化转型,而且会形成庞大的网络黑灰产业,从而带来金融、网络与信息、知识产权等方面的刑事安全风险,给刑法立法、刑事司法带来严重挑战。刑法理论对此需要分别从立法论与解释论上予以积极回应。从立法论上,刑法的积极预防有其界限,应当采取“刑法治理与多元治理并轨、法律治理与技术治理同步、源头治理与重点治理并重、刑法明确与兜底罪名相融”的发展模式。从解释论上,数字经济时代出现的犯罪新形态,对传统刑法理论的管辖论、不法论、归责论、共犯论等均提出新问题,需要提出与建构能动主义解释论。