Time-dependent convection at high latitudes

A fully time-dependent ionospheric convection model, in which electric potentials are derived by an analytic solution of Laplaces equation, is described. This model has been developed to replace the empirically derived average convection patterns currently used routinely in the Sheffield/SEL/UCL coupled thermosphere/ionosphere/plasmasphere model (CTIP) for modelling disturbed periods. Illustrative studies of such periods indicate that, for the electric field pulsation periods imposed, long-term averages of parameters such as Joule heating and plasma density have significantly different values in a time-dependent model compared to those derived under the same mean conditions in a steady-state model. These differences are indicative of the highly non-linear nature of the processes involved.     

Modeling rhamnolipids production by Pseudomonas aeruginosa from immiscible carbon source in a batch system

A mathematical model to predict the rhamnolipids production by Pseudomonas aeruginosa from oleic acid in a two phase liquid-liquid batch reaction system, was developed in this study. The model was based on two theoretical assumptions: 1) the convective oleic acid mass transfer is coupled to a bioreaction in the aqueous liquid bulk, and 2) the volume of the immiscible oleic acid drops and the saturation concentration at the interface are a function of rhamnolipids production. The model was able to accurately predict the experimental growth of the Pseudomonas aeruginosa strain, and the rhamnolipids production data with oleic acid as carbon source. This mathematical approach indicated a high correspondence between the saturation dimensionless profiles of oleic acid at the interface and the experimental profiles of surface tension difference. This modeling approach may constitute a useful tool in the design and scaling-up of bioreactors applied to the production of biosurfactants with immiscible carbon sources.     

Regional Problems in Water Use in Siberian Industrial Agglomerations

Water Resources - The basic indicators of regional water use have been identified and assessed as a component of a single social–natural–technogenic system. These indicators have been...     

Tropospheric Ozone in a Global-Scale Three-Dimensional Lagrangian Model and Its Response to NOX Emission Controls

A three-dimensional Lagrangian tropospheric chemistry modelis used toinvestigate the impact of human activities on the tropospheric distributionofozone and hydroxyl radicals. The model describes the behaviour of 50 speciesincluding methane, carbon monoxide, oxides of nitrogen, sulphur dioxide andnineorganic compounds emitted from human activities and a range of other sources.Thechemical mechanism involves about 100 chemical reactions of which 16 arephotochemical reactions whose diurnal dependence is treated in full. The modelutilises a five minute chemistry time step and a three hour advection timestepfor the 50,000 air parcels. Meteorological data for the winds, temperatures,clouds and so on are taken from the UK Meteorological Office global model for1994 onwards. The impacts of a 50% reduction in European NO_Xemissions onglobal ozone concentrations are assessed. Surface ozoneconcentrations decrease in summertime and rise in wintertime, but to differentextents.     

Homology of solar flare-associated radio events

The concept of homology, introduced by Ellison, Mc Kenna, and Rceid (1960) for optical flares, can be extended to flare-associated radio events. Successive flares within the same centre of activity sometimes produce radio events that are remarkably similar. The similarity amounts to the fact that they extend over about the same range(s) in frequency, producing at each frequency responses of comparable intensity and duration. On some occasions the intensity curves at individual frequencies show even detailed resemblance. The occurrence of homologous radio events is commonly restricted to periods of less than 48 hours.Without being homologous, radio events that occur in the same centre of activity may present a common characteristic that is typical for that centre. Two such characteristics are (1) the production of radio responses at centimetric, decimetric and metric frequencies, and (2) the impulsiveness of microwave outbursts. The distribution of time intervals during which such bursts occur is compared with the same distribution for homologous events (Figure 3).     

Riometer observations in the polar caps of solar cosmic ray events during the IQSY

During the period of the IQSY, January 1964 through December 1965, the sun remained quiet, accelerating few energetic particles. There were many instances during the IQSY when lowenergy detectors on satellites and space probes registered small intensity increases. However, few of these events were associated with protons of energies exceeding 10 MeV. Moreover, the maximum intensities (E _p > 500 keV) were typically 1–8/cm²sec ster. Most of these events were below the threshold of riometer detection.The largest solar cosmic ray event observed in 1964 by polar-based riometers was that of March 16. This event was observed by 30 and 50 Mc/s riometers at McMurdo Sound, Antarctica, and Shepherd Bay, N.W.T., Canada.The largest event in 1965 occurred on February 5 and was the largest during the IQSY. It was associated with a class 2 flare at about 1750 UT, February 5. The propagation time between the sun and Earth was about one hour. This event was well observed by satellites, space probes, and riometers.This paper discusses primarily the 5 February 1965 event. Some discussion is also given to the 16 March 1964 event, other small events during the IQSY, and the recent event in March 1966.     

On the convective instability of finitely conducting viscous model chromosphere

The convective stability of a simple model chromosphere, consisting of protons, electrons and hydrogen atoms in the ground state, has been studied in the presence of a vertically upward uniform magnetic field to include the effects of FLR, Hall-currents, finite conductivity and ionization. The ionization in the chromosphere is collisional and the recombination is radiative. It is found that the Schwarzchild criterion should necessarily be satisfied for the stability together with the condition thatv > 2v ₀, where is kinematic viscosity andv ₀ is gyroviscosity. Some special cases have also been investigated.     

A geoelectrical survey of an area under construction near the Moscow–St. Petersburg highway

The results of a geoelectrical survey of the Mshentsy area located in Tver oblast near the Moscow–St. Petersburg express road, which is under construction, are presented. In order to obtain information about the geological composition of the area and the processes that occur in it (karst and water flow zones ), we performed our measurements using the electrical resistivity imaging, self potential survey, water electrical conductivity and temperature measurements. Using petrophysical resistivity modeling of the rocks, taking the geoelectric data into account, we completed a lithology differentiation of the section and calculated the hydraulic conductivity values of the rocks. By interpreting this data, we found a wide distribution of fractured carbonates that compose the lower part of the section of the studied territory. The conclusion was drawn that the Mshentsy area belongs to the intense local karst zone.     

Thorium and uranium isotopes in a manganese nodule from the Peru basin determined by alpha spectrometry and thermal ionization mass spectrometry (TIMS): Are manganese supply and growth related to climate?

Thorium- and uranium isotopes were measured in a diagenetic manganese nodule from the Peru basin applying alpha- and thermal ionization mass spectrometry (TIMS). Alpha-counting of 62 samples was carried out with a depth resolution of 0.4 mm to gain a high-resolution²³⁰Th_excess profile. In addition, 17 samples were measured with TIMS to obtain precise isotope concentrations and isotope ratios. We got values of 0.06–0.59 ppb (²³⁰Th), 0.43–1.40 ppm (²³²Th), 0.09–0.49 ppb (²³⁴U) and 1.66–8.24 ppm (²³⁸U). The uranium activity ratio in the uppermost samples (1–6 mm) and in two further sections in the nodule at 12.5±1.0 mm and 27.3–33.5 mm comes close to the present ocean water value of 1.144±0.004. In two other sections of the nodule, this ratio is significantly higher, probably reflecting incorporation of diagenetic uranium. The upper 25 mm section of the Mn nodule shows a relatively smooth exponential decrease in the²³⁰Th_excess concentration (TIMS). The slope of the best fit yields a growth rate of 110 mm/Ma up to 24.5 mm depth. The section from 25 to 30.3 mm depth shows constant²³⁰Th_excess concentrations probably due to growth rates even faster than those in the top section of the nodule. From 33 to 50 mm depth, the growth rate is approximately 60 mm/Ma. Two layers in the nodule with distinct laminations (11–15 and 28–33 mm depth) probably formed during the transition from isotopic stage 8 to 7 and in stage 5e, respectively. The Mn/Fe ratio shows higher values during interglacials 5 and 7, and lower ones during glacials 4 and 6. A comparison of our data with data from adjacent sediment cores suggests (a) a variable supply of hydrothermal Mn to sediments and Mn nodules of the Peru basin or (b) suboxic conditions at the water sediment interface during periods with lower Mn/Fe ratios.