PHYSICAL GEOGRAPHY OF TROPICAL LATIN AMERICA: THE SPATIAL AND TEMPORAL HETEROGENEITY OF ENVIRONMENTS     

Karl S. Zimmerer  Ph.D.  Robert P. Langstroth  M.S. 《Singapore journal of tropical geography》1994,14(2):157-172

For the past 40 years, studies of physical geography in tropical Latin America have concentrated on the spatial and temporal diversity of biophysical environments and biota. Environmental heterogeneity arises from historical and present-day interaction between climatic, geomorphologic, edaphic, and biogeographic systems. Recent research emphasizes three major themes involving these systems: Quaternary climate change; human-altered biophysical environments; and geomorphologic activity. Findings on these themes are evaluated with respect to the tropical highlands, the tropical lowlands and related extra-tropical areas. Research on physical geography in Latin America promises numerous contributions toward a better understanding of environmental conservation.  相似文献   

A REVIEW OF PHYSICAL GEOGRAPHY IN SOUTH ASIA     

Vishwas S. Kale  M.A.  M.Phil.  Ph.D. 《Singapore journal of tropical geography》1994,14(2):212-228

The development of physical geography in South Asia has generally followed the British and European trends. Diverse themes from denudational chronology to palaeoflood geomorphology have attracted the attention of geomorphologists, particularly in the last 25 years. In addition, geographers’ interest in climatology and biogeography became pronounced during the 1980s. Major methodological shifts in the late 1960s in the west have affected geographical studies in South Asia. These shifts include the use of methods of quantification, remote sensing data, and the increased importance of field and laboratory studies. The second notable aspect in recent times is the accelerating interest amongst physical geographers in environmental studies and the applied aspects of the discipline as well as an increased interaction with scientists in cognate fields. An attempt is also made to identify the key research themes that will interest physical geographers in the near future.  相似文献   

PHYSICAL GEOGRAPHY IN SOUTHEAST ASIA: PAST THEMES, CURRENT STATUS AND FUTURE TRENDS     

Avijit Gupta  M.A.  Ph.D.  P.P. Wong  M.A.  Ph.D. 《Singapore journal of tropical geography》1994,14(2):252-264

Our knowledge regarding the physical geography of Southeast Asia is incomplete to a surprising extent. This paper reviews the past research, describes the ongoing work, and attempts to identify the future trends. Coverage of such a large area, even for the last 25 years, requires study of publications in several languages and coping with literature which is not easily available. Therefore certain topics. which are prominent in current research and likely to remain so in the future were chosen and reviewed in detail. Such topics include studies related to active plate margin features; the Pleistocene in Southeast Asia; erosion and sedimentation rates; rainforest; river systems; karst in Southeast Asia; coastal geomorphology; and the urban environment. Environmental studies are rapidly gaining importance chiefly because of (a) the destruction of the natural vegetation and the associated loss of biodiversity and (b) the growing problems due to accelerated erosion and sedimentation This trend is likely to continue with accelerated destruction of forests, development of coastal areas, and urbanization of the landscape The direction of research in physical geography of Southeast Asia has been determined by a combination of individual research interest, governmental priorities, and international expectations  相似文献   

FORTY YEARS OF PHYSICAL GEOGRAPHY IN THE JOURNAL     

P.P. Wong  M.A.  Ph.D.  Avijit Gupta  M.A.  Ph.D. 《Singapore journal of tropical geography》1994,14(2):295-309

Up to June 1993, 207 articles on physical geography have been published in the Malayan Journal of Tropical Geography (MJTG) (1953–57), Journal of Tropical Geography (JTG) (1958–79) and the Singapore Journal of Tropical Geography (SJTG) (1980–93). These articles are examined initially in terms of their sub-fields (Biogeography, Climatology, Geomorphology, Hydrology, and Soils), area of focus (the tropics, Africa, America, East Asia, South Asia, Southeast Asia excluding Malaysia and Singapore, Malaysia, Singapore, and Southwest Pacific) and the area of origin of the authors. The more significant papers in the sub-fields are indicated. Various factors influencing the contributions to the Journal and some insights on the contributions of local staff (Singapore and Malaysia) are also given. The significance of the Journal as an avenue for local and foreign authors and for papers on physical geography in the tropics is briefly evaluated.  相似文献   

Finite-amplitude plane waves in deformed Hadamard elastic materials     

Ph. Boulanger    M. Hayes  C. Trimarco 《Geophysical Journal International》1994,118(2):447-458

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Pseudopotential periodic Hartree-Fock study of Mg2SiO4 polymorphs: Olivine,modified spinel and spinel     

B. Silvi  A. Bouaziz  Ph. D'Arco 《Physics and Chemistry of Minerals》1993,20(5):333-340

Pseudopotential periodic Hartree-Fock calculations have been performed on the three polymorphs of Mg₂SiO₄ with a polarized split valence basis set. The energy differences between polymorphs at their experimental geometries are correctly predicted. The olivine to modified spinel and olivine to spinel phase transition pressures have been estimated and agree within a few GPa with their experimental values. The bonding in Mg₂SiO₄ is discussed from the point of view of the, band structures, projected density of states, electron density and electron localization function (ELF) curves. It is concluded that both Mg-O and Si-O bonds are highly ionic.  相似文献   

Aquaculture intensification under land and water limitations     

B. Hepher Ph. D. 《GeoJournal》1985,10(3):253-259

Two intensive aquaculture systems are described in which high yields are obtained for relatively low inputs of land area, water and supplementary feed. The one is a polyculture of a number of fish species in deep cotton irrigation reservoires (5–7 m deep) in Israel. The large volume of water in these reservoirs improves the oxygen regime and dilutes catabolites excreted by the fish. This allows the increase of fish density to 10,000–18,000 fish ha^–1. It also enables the increase of the resevoir's productivity by manuring with liberal amounts of animal wastes. Yields obtained in this system reach over 10 ton ha^–1 yr^–1 at very low feed conversion rates. The second system is practiced in Taiwan for the culture of red tilapia. Pond water is stirred mechanically by paddlewheels to create a gentle current around a central water outlet. This supplies ample oxygen and concentrates wastes in the center of the pond, from where it is removed twice daily, thus alleviating the build-up of catabolite concentration in the pond. Densities of fish amount to 215,000 to 430,000 fish ha^–1, and the yields are accordingly high reaching more than 200 ton ha^–1 yr^–1. The ecological principles involved in these systems are discussed.  相似文献   

A theoretical approach to the kinetics of calcite ⇌ aragonite transition: application to laboratory experiments     

M. Madon  Ph. Gillet 《Earth and Planetary Science Letters》1984,67(3):400-414

A theoretical approach to the calcite ? aragonite transformation is presented for the case of a dislocation glide mechanism obeying first-order kinetics. The kinetic parameters are determined from recent experimental data from the literature; the sensitivity of the model to these and other parameters like the grain size and the deviatoric stresses are discussed.The model results in the definition of what could be the actual transformation domains of the CaCO₃ polymorphs in the (P,T) plane. These domains are different from the classical ones, i.e. different from the stability fields defined with respect to Clapeyron's curve; they can evolve in the (P,T) plane when a deviatoric stress is applied to the system. In this case, we can define a domain in which the two senses of the calcite ? aragonite transition are activated simultaneously.The application of the model to laboratory experiments needs the integration of the kinetic differential equation (K varying withP andT). Using this method, we demonstrate the role of (P,T,t) path on reaction rate and the role of experimental uncertainties on the reaction parametersK andn.Finally, we discuss the problem of the synthesis of polymorphs out of their stability field and of their formation by grinding; these problems, difficult to tackle in terms of diffusion, can be approached with the proposed dislocation transformation kinetic model.  相似文献   

Characteristics of horizontal macroturbulence due to the currents in the Baltic Sea     

Andrzej Jankowski Ph. D.  Zygmunt Catewicz M. Sc. 《Ocean Dynamics》1984,37(5):173-200

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Regional and urban population size weights in Saudi Arabia, 1962–1974     

Makki MS 《GeoJournal》1986,13(2):111-118

The aim of this paper 3s to study the development of population weights for regions and urban centres in Saudi Arabia through the period 1962–1974. In order to achieve this aim some non-parametric statistical rules have been used such as rank-size rule and the four-city index. The results show non-balanced distribution of population on both regional and urban scales. The concentration of people in urban centres is more pronounced than the concentration in regions. This is due to internal and external movement of population towards largesized urban centres. The paper recommends that the official authorities should give more consideration to economic and service development in rural and urban areas that are retreating in ranking and decreasing in population.  相似文献