PUEBLO MISSION CHURCHES AS SYMBOLS OF PERMANENCE AND IDENTITY*

ABSTRACT. The three Pueblo mission churches of San Esteban del Rey, Nuestra Señora de Guadalupe, and San José de Laguna are the most visually striking structures in the western New Mexico pueblos of Acoma, Zuni, and Laguna. Prime examples of “structures of permanence” on the landscape, the churches define local cultural identity. Church permanence and Pueblo identity are expressed in a five‐part typology of visible characteristics: natural materials and hand labor, massive exterior form, adjoining cemeteries, syncretism of interior decorations, and structural decay and rebirth. Permanence must, however, be understood as an evolving condition, undergoing new representations as multicultural relationships evolve.     

FIGHTING FIRE WITH A BROKEN TEACUP: A COMPARATIVE ANALYSIS OF SOUTH AFRICA'S LAND‐REDISTRIBUTION PROGRAM*

ABSTRACT. Since the rise of its first democratically elected government in 1994, South Africa has sought to redress its highly inequitable land distribution through a series of land‐reform programs. In this study we examine land‐redistribution efforts in two of South Africa's provinces, the Western Cape and Limpopo. By analyzing a cross‐section of projects in these two locales we develop a political ecology of stymied land‐reform possibilities to explain the limited progress to date. Given South Africa's ambitious goal of redistributing 30 percent of its white‐owned land by 2014 and the incremental and flawed nature of its redistribution program, we argue that the process is like trying to put out a fire with a broken teacup. Our results are based on interviews with policymakers, commercial farmers, and land‐redistribution beneficiaries, as well as on an analysis of land‐use change in Limpopo Province.     

EFFECTIVE OPTIMAL STRUCTURAL CONTROL OF SOIL–STRUCTURE INTERACTION SYSTEMS

A methodology is developed in this paper to include soil–structure interaction effects in optimal structural control, General Multi-Degree-Of-Freedom (MDOF) structural models are considered. The SSI transfer functions for ground motion and control force in the physical space are presented first, followed by a methodology for using system identification techniques to find an equivalent fixed-base model of an MDOF SSI system. An iterative technique is applied to combine these methods for the determination of optimal control gains. The control effectiveness of considering soil–structure interaction is investigated for the controlled SSI system. It is found that the control algorithm considering SSI effects is more effective than the corresponding control algorithm assuming a fixed-base system model. In addition, the advantage of applying this methodology is observed to be more prominent in the cases where the SSI effects are more significant. © 1997 by John Wiley & Sons, Ltd.     

Satellite remote sensing of river inundation area,stage, and discharge: a review

The growing availability of multi-temporal satellite data has increased opportunities for monitoring large rivers from space. A variety of passive and active sensors operating in the visible and microwave range are currently operating, or planned, which can estimate inundation area and delineate flood boundaries. Radar altimeters show great promise for directly measuring stage variation in large rivers. It also appears to be possible to obtain estimates of river discharge from space, using ground measurements and satellite data to construct empirical curves that relate water surface area to discharge. Extrapolation of these curves to ungauged sites may be possible for the special case of braided rivers. Where clouds, trees and floating vegetation do not obscure the water surface, high-resolution visible/infrared sensors provide good delineation of inundated areas. Synthetic aperture radar (SAR) sensors can penetrate clouds and can also detect standing water through emergent aquatic plants and forest canopies. However, multiple frequencies and polarizations are required for optimal discrimination of various inundated vegetation cover types. Existing single-polarization, fixed-frequency SARs are not sufficient for mapping inundation area in all riverine environments. In the absence of a space-borne multi-parameter SAR, a synergistic approach using single-frequency, fixed-polarization SAR and visible/infrared data will provide the best results over densely vegetated river floodplains. © 1997 John Wiley & Sons, Ltd.     

Photochemical Effects in the Heterogeneous Reaction of Soot with Ozone at Low Concentrations

The soot-ozone reaction at low concentrations (ppm O₃) hasbeen examined todetermine any influence of solar radiation on its products and kinetics. Theeffect of simulatedsolar radiation is to change the product distribution towardsCO₂(g), CO (g) and H₂O(g) at theexpense of soot surface functional groups formation. Little effect on theextent or rate ofdiminution of O₃ through this rapid reaction is observed. Theinitial rate laws for formation ofall products remain the same under simulated solar radiation, with changes inthe rate constants(and thus in the relative importance of mechanistic pathways) responsible forthe differingproduct distributions. Decarboxylation of soot surface functionalities hasbeen shown to be onepossible mechanism underlying these effects. Atmospheric soot, particularlythat emitted nearthe tropopause by increasing numbers of subsonic and supersonic aircraft, mayplay a role inozone depletion; the rapid diminution of ozone in soot's presence isunaffected by solarradiation.     

Mantle-equilibrated Orthopyroxene Eclogite Pods from the Basal Gneisses in the Selje District, Western Norway

‘Country-rock eclogite’ pods occur enclosed withtectonic contacts within heterogeneous amphibolite-facies gneissesin the Basal Gneiss Region of Western Norway. Sixty-nine newmicroprobe analyses for garnets, clino-and orthopyroxenes, olivine,clinoamphiboles, biotite and carbonates from a number of orthopyroxeneeclogite pods in the Selje District are presented. The firstfour minerals are primary whilst the others, of which the amphibolesare described in some detail, formed during a subsequent butstill early stage in eclogite history. The primary minerals have a wider range of compositions thanorthopyroxene eclogites from other geological environments;jadeite-rich clinopyroxene and unusually grossular-poor garnetsare described from this environment for the first time. Sidero-magnesiteoccurs in apparent equilibrium with primary eclogite minerals.The early amphiboles have apparently grown at the expense of,but nevertheless in equilibrium with, primary minerals throughreactions involving OH, K⁺, Na⁺, and possibly Mg-bearing fluids.Magnesio-cummingtonite intergrown with actinolite is recognizedas an early phase in one eclogite pod. The early amphibolescan be distinguished from the symplectitic amphiboles by thelower Al^lv, Al^vl, Ti and alkali contents and Fe/Fe + Mg ratiosand higher Si content of the former minerals. The symplectiticamphiboles form, together with plagioclase, during the stilllater amphibolitization of the eclogites. Fe/Mg distribution coefficients are affected by the Na contentsof clinopyroxenes and probably also by the Fe/Mg contents ofthe bulk assemblages. The former is due largely to increasingacmite content in jadeite-rich clinopyroxenes whilst the latteris tentatively attributed to lower closure temperatures of Fe-richassemblages. The Ca content in garnet is significantly relatedto both of these Na and Fe/Mg factors. Nevertheless a rangeof different distribution coefficients, including the Ca/Ca+ Mg ratio in coexisting pyroxenes, suggests a very limitedrange of temperatures of equilibration, the best estimate ofwhich is 700–850 °C. Pressures of equilibration are more difficult to assess. Onemodel, based upon the assumption of the stable occurrence ofamphiboles together with primary minerals and upon the minimumpressures necessary to transform a range of rock types to eclogite,suggests pressures of 15–28 kb at 700–850°C.A second model, based upon the Al₂O₃ content of primary orthopyroxeneand upon the association of sidero-magnesite with pyroxenes,suggests higher pressures (30–45 kb) over the same temperaturerange. Amphiboles are not stable under these conditions andare considered to form during a subsequent lower pressure (15–28kb) event when the low Al₂O₃ orthopyroxenes and sidero-magnesitesurvive metastably during an essentially isothermal history. One eclogite pod contains minerals with coarse exsolution lamellae:orthopyroxene exsolving garnet and clinopyroxene exsolving orthopyroxene.These imply high T-P processes, roughly estimated at 1200–1370°C, 30–40 kb, and hence suggest eclogite generationby igneous fractionation processes. Four T-P regimes (A, B, C, D) of mineral equilibration are recognizedin the history of the Selje district orthopyroxene eclogites,between their prior origin, presumably in the upper mantle,and their present surface exposure. This initial eclogite fractionation(regime A) occurred in an olivine-poor rather than olivine-richupper mantle environment, followed by cooling, exsolution, recrystallizationand re-equilibration (regime B) in a Precambrian tectonic environment.Subsequent history involved mineral reaction, metasomatism,and probably chemical redistribution through the medium of amphibole-formingfluids (regime C) and finally Caledonian tectonic transportinto poly-metamorphic continental basement where their survivalis thought to be due to a low activity of water. Marginal symplectiticamphibolitization (regime D), due to localized fluxing of metamorphicfluids, was the last significant petrological event prior touplift and exposure. The processes of tectonic transport aretentatively considered to represent deep level obduction processesrelated to continent/continent collision.     

HILLS AS RESOURCES AND RESISTANCES IN SYRACUSE,NEW YORK*

In an example of what William Freudenburg and his colleagues called the “conjoint construction” of nature and society, hills may represent either assets or liabilities for urban settlement, depending on the period and the activities involved. The relationships between terrain and land use in Syracuse, New York, since the late eighteenth century fall into three major eras. The initial phase, in which settlement largely shunned the lowlands, gave way in the 1820s to one in which canals and railroads stimulated development of the lowlands and in which most land uses, save those of the classic urban fringe, avoided the uplands. A new pattern appeared in the late nineteenth century with the arrival of the electric trolley and the automobile and with provision of a municipal water supply able to reach the city's high ground. Development since then has been consistent with Ernest Burgess's 1929 model of “the poor in the valleys, the well‐to‐do on the hillslopes, and the rich on the hilltops.”     

黄河三角洲滨海湿地健康条件评价概念模型

滨海湿地健康与生物学特征主要取决于区域上的水文与盐度体制以及景观尺度上的土地利用现状。然而,由于滨海湿地条件评价的指标和标准并不十分清楚,因此,对滨海湿地系统条件进行评价,目前仍是环境科学的难点。中国地质调查局（CGS）青岛海洋地质研究所与美国地质调查局湿地研究中心合作先后为美国密西西比河下游生态环境及中国黄河三角洲（YRD）滨海湿地评价建立了概念模型。本文将陈述YRD湿地评价的概念模型。此模型的建立在于确定滨海湿地当前的条件和随时间改善或退化的过程,以及确定优先管理的区域。CGS项目之所以选取YRD作为滨海湿地的研究对象主要是因为它具有重要的生态意义。由于上游来水减少或黄河断流,该区湿地生境十分脆弱。本文提出此概念模型可为今后湿地条件评价指标确定、调查研究活动和数据采集提供指导。通过该模型的构建,使环境变化可用具体指标来度量,从而服务于滨海湿地生态系统的保护与管理活动。