Regional population redistribution in the USSR: 1979-84     

Rowland RH 《Soviet geography》1986,27(3):158-182

"The primary purpose of this paper is to assess very broadly the regional growth and redistribution of the total, urban and rural populations of the USSR, as well as aggregate, regional and city size patterns of urbanization for the 1979-84 period. In order to investigate the continuity or reversal of trends, comparisons with preceding intercensal periods will also be undertaken, particularly with the 1970-79 period." It is found that "regional rates of population change between 1979 and 1984 were generally lower than those of 1970-79, primarily due to a general decline in natural increase rates. In addition, regional variations in rates of population change for the 1979-84 period were similar to those of the 1970-79 period.... The USSR has apparently reversed its long-term trend of deconcentration in the sense that the population as a whole is becoming more concentrated again, but this time in a new area of concentration, Central Asia, which is now the most populous economic region."  相似文献   

Variations in structures and distributions of C₂₅ highly branched isoprenoid (HBI) alkenes in cultures of the diatom, Haslea ostrearia (Simonsen)     

E. J. Wraige  S. T. Belt  C. A. Lewis  D. A. Cooke  J. -M. Robert  G. Mass  S. J. Rowland 《Organic Geochemistry》1997,27(7-8)

The highly branched isoprenoid (HBI) alkenes of three batch cultures of the diatom Haslea ostrearia have been examined and the occurrence of C₂₅ tri-, tetra- and pentaenes confirmed. Growth of cultures outside at ambient temperature, under natural sunlight, in May (6 days) and June (10 days) 1995 and monitoring of HBI concentrations in samples collected daily and stored frozen, revealed that in May greater concentrations of HBIs (ca 6500 fg cell⁻¹) were produced than in June and at a much earlier stage of growth. Furthermore, in May the HBIs were more unsaturated (predominantly a tetraene rather than a triene). The reasons for these differences are at present unknown and future investigations of the effect of irradiance, temperature, salinity and other environmental variables are required. Such experiments may allow the various HBI distributions in the alga and in sediments to be better understood and, like some other polyunsaturated lipids, HBI alkenes may become useful environmental and palaeoenvironmental indicators. Two previously unreported alkenes, 2,6,10,14-tetramethyl-7-(3-methylpent-4-enyl)pentadec-2,5,9,13-ene (GC retention index, 2201_DB-1) and 2,6,10,14-tetramethyl-7-(3-methylene pent-4-enyl)pentadec-2,5,9,13-ene (GC RI, 2248_DB-1) from a batch culture of Haslea ostrearia grown in October/November 1993 and stored frozen for over a year, have also been isolated and characterised by ¹³C and ¹H NMR, epoxide derivatisation and mass spectrometry. Such structural characterisation studies of HBI alkenes should also aid our understanding of the geochemical fate of these widely distributed hydrocarbons.  相似文献   

An investigation of the sources and seasonal variations of highly branched isoprenoid hydrocarbons in intertidal sediments of the Tamar Estuary, UK     

S. J. Hird  S. J. Rowland 《Marine environmental research》1995,40(4)

The concentrations and distributions of highly branched isoprenoid (HBI) hydrocarbons in the surficial sediments of an intertidal mudflat in the Tamar Estuary, UK, were examined at monthly intervals throughout 1990. C₂₀ and C₂₅ HBIs were present all the year round and their concentrations covaried, maximising at several times in the year, notably in April–June. Since C₂₅ HBIs are known to be produced by a species of diatom (Haslea ostrearia) in culture, it seemed likely that the sedimentary maxima were also due to production from sediment diatoms. It was interesting therefore that the April–June HBI maximum did not coincide with the (August) maximum concentration of the common diatom hydrocarbon n-heneicosa-hexaene (HE), even though HE is also produced by the diatom species which produces C₂₅ HBIs in culture. Diatoms isolated from the sediments in August produced abundant HE and only a small proportion of C₂₅ HBIs. These results suggest that HBI and HE production maximise at different diatom growth stages, or that the major sources of HBIs in the sediments are as yet unidentified diatom species. The diatoms isolated from the sediment did not produce C₂₀ HBIs and to date no organism has produced these in culture. Nonetheless, the δ¹³C values of the sedimentary C₂₀ HBIs were consistent with an algal source.  相似文献   

A FURTHER INVESTIGATION OF URBANIZATION AND INDUSTRIALIZATION IN PRE-REVOLUTIONARY RUSSIA*     

Robert A. Lewis  Richard H. Rowland 《The Professional geographer》1974,26(2):177-182

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Recent declining and stagnant towns of the USSR     

Rowland RH 《Soviet geography》1980,21(4):195-218

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Fault growth at a nascent slow-spreading ridge: 2005 Dabbahu rifting episode, Afar   总被引：3，自引：0，他引：3  

J. V. Rowland  E. Baker  C. J. Ebinger  D. Keir  T. Kidane  J. Biggs  N. Hayward  T. J. Wright 《Geophysical Journal International》2007,171(3):1226-1246

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The changing morphology of an open lava channel on Mt. Etna     

John E. Bailey  Andrew J. L. Harris  Jonathan Dehn  Sonia Calvari  Scott K. Rowland 《Bulletin of Volcanology》2006,68(6):497-515

An open channel lava flow on Mt. Etna (Sicily) was observed during May 30–31, 2001. Data collected using a forward looking infrared (FLIR) thermal camera and a Minolta-Land Cyclops 300 thermal infrared thermometer showed that the bulk volume flux of lava flowing in the channel varied greatly over time. Cyclic changes in the channel's volumetric flow rate occurred over several hours, with cycle durations of 113–190 min, and discharges peaking at 0.7 m³ s⁻¹ and waning to 0.1 m³ s⁻¹. Each cycle was characterized by a relatively short, high-volume flux phase during which a pulse of lava, with a well-defined flow front, would propagate down-channel, followed by a period of waning flow during which volume flux lowered. Pulses involved lava moving at relatively high velocities (up to 0.29 m s⁻¹) and were related to some change in the flow conditions occurring up-channel, possibly at the vent. They implied either a change in the dense rock effusion rate at the source vent and/or cyclic-variation in the vesicle content of the lava changing its bulk volume flux. Pulses would generally overspill the channel to emplace pāhoehoe overflows. During periods of waning flow, velocities fell to 0.05 m s^–1. Blockages forming during such phases caused lava to back up. Occasionally backup resulted in overflows of slow moving ‘a‘ā that would advance a few tens of meters down the levee flank. Compound levees were thus a symptom of unsteady flow, where overflow levees were emplaced as relatively fast moving pāhoehoe sheets during pulses, and as slow-moving ‘a‘ā units during backup. Small, localized fluctuations in channel volume flux also occurred on timescales of minutes. Volumes of lava backed up behind blockages that formed at constrictions in the channel. Blockage collapse and/or enhanced flow under/around the blockage would then feed short-lived, wave-like, down-channel surges. Real fluctuations in channel volume flux, due to pulses and surges, can lead to significant errors in effusion rate calculations. Editorial responsibility: A. Woods  相似文献   

Thick lava flows of Karisimbi Volcano, Rwanda: insights from SIR-C interferometric topography     

Mary E. MacKay  Scott K. Rowland  Peter J. Mouginis-Mark  Harold Garbeil 《Bulletin of Volcanology》1998,60(4):239-251

 We use a digital elevation model (DEM) derived from interferometrically processed SIR-C radar data to estimate the thickness of massive trachyte lava flows on the east flank of Karisimbi Volcano, Rwanda. The flows are as long as 12 km and average 40–60 m (up to >140 m) in thickness. By calculating and subtracting a reference surface from the DEM, we derived a map of flow thickness, which we used to calculate the volume (up to 1 km³ for an individual flow, and 1.8 km³ for all the identified flows) and yield strength of several flows (23–124 kPa). Using the DEM we estimated apparent viscosity based on the spacing of large folds (1.2×10¹² to 5.5×10¹² Pa s for surface viscosity, and 7.5×10¹⁰ to 5.2×10¹¹ Pa s for interior viscosity, for a strain interval of 24 h). We use shaded-relief images of the DEM to map basic flow structures such as channels, shear zones, and surface folds, as well as flow boundaries. The flow thickness map also proves invaluable in mapping flows where flow boundaries are indistinct and poorly expressed in the radar backscatter and shaded-relief images. Received: 6 September 1997 / Accepted: 15 May 1998  相似文献   

Variations in distributions of C₂₅ highly branched isoprenoid (HBI) alkenes in the diatom, Haslea ostrearia: influence of salinity     

E.J. Wraige  S.T. Belt  G. Massé  J.-M. Robert  S.J. Rowland 《Organic Geochemistry》1998,28(12):855-859

C₂₅ HBI alkenes of the diatom, Haslea ostrearia, have been examined in experiments in which the algae were cultured for up to 10 days at 14–15°C at nine different salinities (15 to 40 per mil). H. ostrearia proved to be an osmotolerant organism and growth was observed at all salinities. After 10 days growth at the lowest and highest salinities of 15 and 40 per mil, the concentrations of 2,10,14-trimethyl-6-methylene-7-(3-methylpent-1-enyl)pentadec-9-ene, which was the only HBI present in any of the samples, averaged 1.2±0.7 and 2.1±0.7 pg cell⁻¹, respectively. These were slightly lower than the HBI concentrations at 25 to 35 per mil (2.8±0.5 pg cell⁻¹). The data indicate that although salinity has an influence on HBI production in H. ostrearia, factors other than salinity are probably more important in controlling the large variations of HBI alkene concentrations and distributions found in sedimentary environments.  相似文献   

The effects of thermal maturity on distributions of dimethylnaphthalenes and trimethylnaphthalenes in some Ancient sediments and petroleums     

R Alexander  R.I Kagi  S.J Rowland  P.N Sheppard  T.V Chirila 《Geochimica et cosmochimica acta》1985,49(2):385-395

The distributions of di- and trimethylnaphthalenes in two sedimentary sequences from Western Australia have been examined by capillary gas chromatography and combined gas chromatography-mass spectrometry. A general decrease was observed in the relative proportions of αα-dimethylnaphthalenes and ααβ-trimethylnaphthalenes with increasing thermal maturity. Similar trends were also observed for six crude oils which have very different ratios of ethylcholestane epimers indicating very different thermal histories. These results suggest that changes in the relative abundances of certain methyl substituted naphthalenes may be useful indicators of thermal maturity of sedimentary organic matter, and the use of a number of isomer ratios is illustrated.  相似文献