OLIGOPOLISTIC COMPETITION AND ECONOMIC GEOGRAPHY*

ABSTRACT This paper studies a general equilibrium model of economic geography in which firms engage in oligopolistic competition. This framework is conducive to analytic results. With increasing returns, oligopolistic competition leads to interindustry trade between regions rather than intraindustry trade. The choice of appropriate technology is a channel of concentration of industries.     

Stories behind the fortress: Stable isotope analysis and 14C dating of soldiers' remains from the Bayanbulag site,Mongolia

Stable carbon and nitrogen isotope analysis of 15 individuals buried closed to Bayanbulag site or the Shouxiangcheng fortress in southern Mongolia revealed complex dietary features. Only one individual had a diet similar to that of the pastoral population in northern China, while the others, who had varying carbon isotope values and low nitrogen values, might have been from different agricultural areas. ¹⁴C dating results suggest that the earliest interment could be much earlier than the building of Shouxiangcheng fortress recorded in Han texts. Analysis of the burial arrangement further confirmed that these deceased were not buried at the same time.     

敦煌、吐鲁番文书所见“舍”之记载差异及其用途探微

敦煌文书与吐鲁番文书对于“舍”的记载内容存在很大差异,仅就敦煌文书而言,其在不同时期对于“舍”的记载格式也有所不同。敦煌文书与吐鲁番文书记载内容的差异,反映了两地居民在各自特殊地理条件下的居住形态及田地经营方式的不同;而敦煌文书记载格式的变化,则反映出不同政权统治下敦煌地区均田制实施情况的差别。此外,敦煌、吐鲁番文书中的“舍”具有不同的用途,明确这一区别,有助于更加深入地理解中古时期两地居民的社会生活状况。     

魏晋十六国北朝关中侨置武都郡研究

前秦时关中氐人分布的武都是指侨置武都郡。侨置武都郡始于曹魏。曹魏为与蜀汉争夺陇右,将武都氐人迁徙至关中,并先后在小槐里和美阳设置武都郡以进行管理。西晋江统的《徙戎论》反映出此时关中武都氐聚居的地方未置武都郡。十六国初期屠各刘氏和羯族石氏先后统治关中,将大量氐羌迁往关东,因此这一时期在关中侨置武都郡缺乏现实基础。苻健立国关中后,在战略要地宝鸡附近侨置武都郡,是其氐人本位政策的体现。北魏时侨置武都郡始领县级行政单位,统治范围扩大,标志着氐人的关中化,同时它也是太武帝平定盖吴叛乱时分化关中南道氐人的重要战略举措。西魏北周立国关中后受政区滥置影响,武都郡领县减少。隋开皇间侨置武都郡在当权者废郡、保留州县的地方行政政策的影响下消失于历史舞台。     

Conodonts and tabulate corals from the Upper Ordovician Angullong Formation of central New South Wales,Australia

Zhen, Y.Y., Wang, G.X. &; Percival, I.G., August 2016. Conodonts and tabulate corals from the Upper Ordovician Angullong Formation of central New South Wales, Australia. Alcheringa 41, xxx–xxx. ISSN 0311-5518.

The Angullong Formation is the youngest Ordovician unit exposed in the Cliefden Caves area of central New South Wales. Its maximum age is constrained by a Styracograptus uncinatus graptolite Biozone fauna at the very top of the underlying Malongulli Formation, but the few fossils previously reported from higher in the Angullong Formation are either long-ranging or poorly known. From allochthonous limestone clasts in the middle part of the formation, we document a conodont fauna comprising Aphelognathus grandis, A. solidum, Aphelognathus sp., Aphelognathus? sp., Belodina confluens, Drepanoistodus suberectus, Panderodus gracilis, Panderodus sp., Phragmodus undatus, Pseudobelodina inclinata and Pseudobelodina? sp. aff. P. obtusa, which supports correlation with the Aphelognathus grandis Biozone (late Katian) of the North American Midcontinent succession. The species concepts of Aphelognathus and Pseudobelodina are reviewed in detail. Associated corals are exclusively tabulates, dominated by agetolitids, including Agetolites angullongensis sp. nov., Heliolites orientalis, Hemiagetolites breviseptatus, Hemiagetolites sp. cf. H. spinimarginatus, Navoites sp. cf. N. circumflexa, Plasmoporella bacilliforma, P. marginata, Quepora sp. cf. Q. calamus and Sarcinula sp. Affinities of the coral fauna from the Angullong Formation are closer to faunas from northern NSW and northern Queensland than to the locally recognized Fauna III of late Eastonian age in central NSW. We propose a subdivision of Fauna III to account for this difference, with the late Katian Fauna IIIB characterized by the incoming of agetolitid corals. The currently known distribution of representatives of this group with adequate age constraints suggests that agetolitids possibly originated in North China, subsequently migrating to Tarim, South China and adjacent peri-Gondwanan terranes while also spreading eastward to northern Gondwana, where they progressively moved through eastern Australia to reach the central NSW region by the early Bolindian.

Yong Yi Zhen* (yong-yi.zhen@industry.nsw.gov.au) and Ian G. Percival (ian.percival@industry.nsw.gov.au), Geological Survey of New South Wales, W.B. Clarke Geoscience Centre, 947–953 Londonderry Road, Londonderry, NSW 2753, Australia; Guangxu Wang (gxwang@nigpas.ac.cn), State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, 39 East Beijing Road Nanjing 210008 PR China.     

Real-Time Dynamic Hybrid Testing Coupling Finite Element and Shaking Table

In this article, a Simulink simulation block with the finite element function is developed on the basis of S-function and implemented as the numerical substructure of real-time dynamic hybrid testing. Thereby, a real-time dynamic hybrid testing system coupling finite element calculation and shaking table testing is achieved. Using the developed system, a shear frame mounted on the soil foundation is tested, in which the shear frame is simulated as the physical model and the foundation is simulated as the finite element model with 132 degrees of freedom. Several cases of the dynamic behavior of soil-structure interaction are studied.     

Fluid effect on hydraulic fracture propagation behavior: a comparison between water and supercritical CO2‐like fluid

The initiation of hydraulic fractures during fluid injection in deep formations can be either engineered or induced unintentionally. Upon injection of CO₂, the pore fluids in deep formations can be changed from oil/saline water to CO₂ or CO₂ dominated. The type of fluid is important not only because the fluid must fracture the rock, but also because rocks saturated with different pore fluids behave differently. We investigated the influence of fluid properties on fracture propagation behavior by using the cohesive zone model in conjunction with a poroelasticity model. Simulation results indicate that the pore pressure fields are very different for different pore fluids even when the initial field conditions and injection schemes (rate and time) are kept the same. Low viscosity fluids with properties of supercritical CO₂ will create relatively thin and much shorter fractures in comparison with fluids exhibiting properties of water under similar injection schemes. Two significant times are recognized during fracture propagation: the time at which a crack ceases opening and the later time point at which a crack ceases propagating. These times are very different for different fluids. Both fluid compressibility and viscosity influence fracture propagation, with viscosity being the more important property. Viscosity can greatly affect hydraulic conductivity and the leak‐off coefficient. This analysis assumes the in‐situ pore fluid and injected fluid are the same and the pore space is 100% saturated by that fluid at the beginning of the simulation.     

评迈内克的“国家理由”研究和马基雅维里的国家权力学说

本文主要评述历史学家迈内克在研究国家理由问题时所表现出的历史道德理想主义特点。正是这种理想主义导致迈内克对马基雅维里国家权力等思想的论述失之偏颇。因此,完整地分析、理解马基雅维里国家权力等思想的结构,这不仅对理解马基雅维里的国家理由观,还对理解学术界的各种国家理由批评有所裨益。     

10世纪前中国西北边疆发展的几个特点

10世纪前的中国西北边疆经历了开拓、稳定和演变等过程,构成了一个相对完整的发展阶段,边疆发展的各种形态与主要特点尽皆呈现。南农北牧既是西北边疆的基本经济形态,也是历史上中原农业王朝与北方游牧民族角逐态势延伸的主要依据;在作为边疆主体的中原或内地王朝、客体的西域地区和旁体的北方游牧民族等三个主要因素的共同作用下,西北边疆的政治地理范围时有伸缩,而多种统治体制并存、边疆问题与民族问题一体化等特点也贯穿于这一时期西北边疆发展的整个过程。