Experimental research on critical point hypothesis

According to the critical point hypothesis (CPH), energy release would accelerate in power law before occurrence of large earthquakes or failure of brittle materials. In the paper, CPH was studied by acoustic emission experiments of large-scale rock samples. Three kinds of rock samples were used in the experiments. The tri-axial loading condition was applied under different loading histories. The released elastic energy (Acoustic emission) was recorded with acoustic emission technique as microcracks emerged and developed inside the rock samples. The experimental results gave a further verification on the CPH. The elastic energy release of rock samples would accelerate before the failure even under different experimental conditions. Primary studies were also made on medium-term earthquake prediction by using accelerating energy release (AER) in the paper. Foundation item: Project of Natural Sciences Foundation of China (10232050), Project of State Key Basic Research (2002CB412706) and Project of Computer Network Information Center, Chinese Academy of Sciences (2002CB412706).     

Geochemical Baselines of Nickel and Chromium in Various Surficial Materials in the Barents Region, NW Russia and Finland

The geochemical baselines of nickel and chromium were studied from the data produced by the Barents Ecogeochemistry project, a large international regional geochemical mapping exercise. The project surveyed major and trace element distributions in stream water, organic and mineralogically-modified soil horizons, and terrestrial moss in the northwestern part of Russia and in Finland. Other materials were collected during the pilot phase and later from thirty special sites. The results on respective materials by XRF, ICP-MS and ICP-AES showed that both geological and anthropogenic factors have an influence on the geochemical baseline concentrations of Ni and Cr in organic soil and stream water. The main explanation of the observed distribution patterns in terrestrial moss is human activity, but geological factors can also affect the baselines. The variation of geochemical baselines in the mineral-rich soil horizon depends only on variations in bedrock. The mineralogy of samples mainly controls the leachability properties of soil samples.     

Angular momentum transport in the solar nebula

Summary It is proposed that gravitational torques can furnish a mechanism for the radial outward transport of angular momentum in the solar nebula. For this effect to be present the disc of the nebula must have a spiral structure with trailing arms. A mathematical model is constructed with the main object of seeing whether purely advective inward eddy transports of angular momentum could offset the gravitational torques. It is found that for a protosun much more massive than the disc the eddy transport is small, allowing the gravitational effects of predominate. In such a case convergence of angular momentum is to be expected at the outer edge of the disc. The possibility exists that matter could be shed to large distances perhaps giving rise to the cloud of comets surrounding the solar system as proposed byJ. H. Oort.     

Mechanics of eddy processes in the tropical troposphere

Summary It is suggested on the basis of the study of observational data gathered byJ. P. Peixoto that the eddy processes in the tropical regions of the middle troposphere operate in an inverse manner as compared with a normal heat engine. Thus, in common with the situation in the lower stratosphere, the region is characterized by a countergradient horizontal eddy heat transport and a rising of colder air and sinking of warmer air on the scale of the large eddy processes.The research reported in this paper was sponsored by the Air Force Cambridge Research Laboratory, under Contract Nos. AF19(604)-6108 and AF19(628)-2408.     

Trends of thought concerning meteorological research

Summary Certain problems of synoptic meteorology relating to the nature of the large quasi-stationary cyclonic and anticyclonic centers aloft are examined from the standpoint of an hypothesis which seeks to connect their maintenance with that of the smaller transient disturbances. The suggested link between these two scales of eddies is in many ways similar to that operating in the general circulaton in order to account for the sustained existence of the circumpolar mean zonal motions, according to the more modern concepts. Newer views concerning the dynamcis of large convective processes, and the essential nonlinearity of the laws governing motions in the atmosphere, figure importantly in the arguments advanced.

---

Zusammenfassung Gewisse Probleme der synotischen Meteorologie im Zusammenhang mit der Natur von grossen halb-stationären zyklonischen und antizyklonischen Zentren in der höheren Atmosphäre werden von einem hypothetischen Standpunkt aus untersucht; und es wird versucht, deren Bestehen in Zusammenhang zu bringen mit dem Vorhandensein von kleineren, vorübergehenden Störungen. Der vorgeschlagene Zusammenhang zwischen diesen beiden Arten von Wirbel-Systemen ähnelt in vielen Beziehungen der allgemeinen Zirkulation, die verantwortlich ist für das fortwährende Bestehen der zirkumpolaren durchschnittlichen zonalen Strömungen, wie sie zufolge modernerer Auffassungen erklärt werden. Neuere Standpunkte, die die Dynamik von grossen konvektiven Vorgängen in der Atmosphäre und die nicht-linearen Gesetze im Hinblick auf die atmosphärischen Strömungs-Gesetze betreffen, werden hauptsächlich in der folgenden Abhandlung untersucht.

     

Hydrodynamical red-shift phenomena in geophysics

Summary By the term red-shift is here meant a transfer of spectral energy from smaller disturbances to larger ones in particular regions of the spectrum. An instance of such action is cited in the behavior of certain wind systems of the atmosphere. It is suggested that this process is given a unique average direction through the agency of friction which prevents too large an accumulation of energy in the graver modes of motion. A second probable similar circumstance is cited in the case of the Gulf Stream, for which proper, data have recently been obtained for the first time.The possibility of the existence of a third instance of this type of red-shift is considered for the propagation of surface waves for long distances over deep water. The subject is treated from the standpoint of a nonlinear theory for wave propagation, investigated previously by the writer. An indication is obtained that a red-shift effect should be observed especially in the forward portion of a wave group which has travelled a large distance into new water.

---

Zusammenfassung Unter dem Ausdruck «Rot-Verschiebung» wird hier die Verschiebung der Spektral-Energie von kleineren zu grösseren Störungen in, ausgesuchten Zonen des Spektrums verstanden. Ein Beispiel eines solchen Vorfalles ist hier besprochen in dem Verhalten, von gewissen Wind-Systemen der Atmosphäre. Es wird angeraten, dass diesem Prozess eine einzige Durchschnittsrichtung durch Reibung gegeben wird, die eine zu grosse Anhäufung von Energie in den ernsteren Bewegungsarten verhindert. Ein zweiter, ziemlich gleicher Umstand wird im Falle des Golfstromes besprochen, für den zum ersten Mal ausführliche Daten vorhanden sind.Die Möglichkeit des Vorhandenseins eines dritten Vorfalles von dieser Art der «Rot-Verschiebung» wird in der Fortpflanzung von Oberflächen-Wellen über längere Entfernungen an tiefem Wasser in Erwägung gezogen. Dieser Fall wird vom Gesichtspunkt einer nichtlinearen Theorie für Wellen-Fortpflanzung betrachtet, die früher vom Autor untersucht wurde. Man gewinnt den Eindruck, dass ein «Rot-Verschiebungs-Effekt» besonders in dem vorderen Teil einer Wellen-Gruppe beobachtet werden kann, besonders dann, wenn die Welle sich eine längere Strecke über frisches Wasser bewegt hat.

---

Résumé Par le terme «red-shift» on veut ici signifier un transfert d'énergie spectrale des plus petites perturbations aux plus grandes dans des régions particulières du spectre. Un exemple de telle action est cité dans le comportement de certains systèmes des vents dans l'atmosphère. On suggère qu'une direction unique soit donnée à ce procès par voie du frottement qui empêche une trop grande accumulation d'énergie dans les modes plus graves du mouvement. Une deuxième probable circonstance similaire est citée dans le cas du Courant du Golfe pour lequel les données convenables ont été récemment obtenues pour la première fois.La possiblité de l'existence d'un troisième exemple de ce genre de «red-shift» est considérée pour la propagation des ondes de surface pour les grandes distances dans les eaux profondes. Le sujet est traité du point de vue d'une théorie nonlinéaire pour la propagation des ondes qui a été développée précédemment par l'auteur. Une indication est obtenue que l'effet d'un «red-shift» devrait être observé specialement dans la region frontale du groupe d'ondes qui a parcouru une grande distance dans des eaux nouvelles.

     

THE HUMAN GEOGRAPHY OF SOUTHEAST ASIA: AN ANALYSIS OF POST-WAR DEVELOPMENTS

This paper reviews the directional shifts in human geographical research on Southeast Asia from 1945 to the present. It first begins with an overview of the identity of the region as conceived in various cultural traditions, such as the Greek, Arabic and Indian traditions. This is followed by an evaluation of regional geographies of Southeast Asia in the post-war period, highlighting the pre-eminence of the geostrategic definition of the region and the failure to come to grips with its rich cultural-historical identity. The paper then goes on to show that, arising from the changes in conceptual developments and methodologies in geography, the early regional emphasis then shifted to systematic concerns, with a movement away from ‘encyclopaedic’ to ‘adjectival’ geography (economic, urban, population, political, cultural and historical) and a greater emphasis on issues concerning national development. Since the 1980s, there have also been fewer regional works on Southeast Asia and though there are now many more indigenous geographers within the region, much of their research is based on their own national or provincial areas. However, this may shift again, given that rapid economic growth has now given the region prominence. Certainly, there is renewed multi-disciplinary interest in Southeast Asia.     

A preliminary mass balance model of primary productivity and dissolved oxygen in the Mississippi River Plume/Inner Gulf Shelf Region

A deterministic, mass balance model for phytoplankton, nutrients, and dissolved oxygen was applied to the Mississippi River Plume/Inner Gulf Shelf (MRP/IGS) region. The model was calibrated to a comprehensive set of field data collected during July 1990 at over 200 sampling stations in the northern Gulf of Mexico. The spatial domain of the model is represented by a three-dimensional, 21-segment water-column grid extending from the Mississippi River Delta west to the Louisiana-Texas border, and from the shoreline seaward to the 30–60 m bathymetric contours. Diagnostic analyses and numerical experiments were conducted with the calibrated model to better understand the environmental processes controlling primary productivity and dissolved oxygen dynamics in the MRP/IGS region. Underwater light attenuation appears relatively more important than nutrient limitation in controlling rates of primary productivity. Chemical-biological processes appear relatively more important than advective-dispersive transport processes in controlling bottom-water dissolved oxygen dynamics. Oxidation of carbonaceous material in the water column, phytoplankton respiration, and sediment oxygen demand all appear to contribute significantly to total oxygen depletion rates in bottom waters. The estimated contribution of sediment oxygen demand to total oxygen-depletion rates in bottom waters ranges from 22% to 30%. Primary productivity appears to be an important source of dissolved oxygen to bottom waters in the region of the Atchafalaya River discharge and further west along the Louisiana Inner Shelf. Dissolved oxygen concentrations appear very sensitive to changes in underwater light attenuation due to strong coupling between dissolved oxygen and primary productivity in bottom waters. The Louisiana Inner Shelf in the area of the Atchafalaya River discharge and further west to the Texas border appears to be characterized by significantly different light attenuation-depth-primary productivity relationships than the area immediately west of the Mississippi Delta. Nutrient remineralization in the water column appears to contribute significantly to maintaining chlorophyll concentrations on the Louisiana Inner Shelf.     

Geochemical Types of Granitoids of the Mongol—Okhotsk Belt and Their Geodynamic Settings

The following geochemical types of granitoids have been investigated in the Mongol-Okhotsk belt:tholetitic,palingenic calc-alkaline,latitic,plumasitic and arpaitic rare-metal granites.Plagiogranites of the tholeiitic series occur within the Mongol-Okhotsk suture,indicating a subduction environment.The calc-alkaline granitoids responsible for the batholith-like intrusions and their formation are related to collision environments.The latest granitoids of the latite series and rare-metal granites came into existence after the collision of continental masses,providing evidence of intraplate magmatism.     

Rate constants for reactions of OH radicals with some Br-containing haloalkanes

Rate constants have been measured for the gas-phase reactions of hydroxyl radical with two halons and three of their proposed substitutes and also with CHClBr-CF₃ using the discharge-flow-EPR technique over the temperature range 298–460 K. The following Arrhenius expressions have been derived (units are 10^–13 cm³ molecule^–1 s^–1): (9.3 _–0.9 ^+1.0 ) exp{–(1326±33)/T} for CHF₂Br; (7.2 _–0.6 ^+0.7 ) exp{–(1111±32)/T} for CHFBrCF₃; (8.5 _–0.8 ^+0.9 ) exp{–(1113±35)/T} for CH₂BrCF₃; (12.8 _–1.2 ^+1.5 ) exp{–(995±38)/T} for CHClBrCF₃. The rate constants at 298 K have been estimated to be <2×10^–17 cm³ molecule^–1 s^–1 for CF₃Br and CF₂Br—CF₂Br. The atmospheric lifetimes due to hydroxyl attack have been estimated to be 5.5, 3.3, 2.8, and 1.2 years for CHF₂Br, CHFBr—CF₃, CH₂Br—CF₃ and CHClBr—CF₃, respectively.