Toxicological effects of biocide Slimicide C-30 on some marine invertebrates

Sublethal and lethal effects of biocide Slimicide C-30 on the developmental stages of mussels Mytilus galloprovincialis and juvenile and adult mysid Leptomysis mediterranea were studied.Biocide at a concentration as low as 0.02 mg l^?1 caused an incipient effect in the embryonic development of mussels where a decreased number of normally developed larvae from eggs was evident. Slimicide C-30 effective concentration (EC 50/96) was 0.07 mg l^?1.In the mysids, the median lethal concentration (96 h LC₅₀) was 0.11 mg l^?1.Previous incubation of Slimicide C-30 at 38°C affected a small delay in mortality time (LT₅₀) but did not cause marked change in the acute toxicity to mysids.     

Resistance to flow in rough supercritical sheet flow

Shallow water depths on steep slopes of as much as fifty per cent can be measured easily by weighing a light flume and the water it contains. Because water accelerates along the flume, a good approximation of the steady state depth is obtained when the recording balance is fixed to its bottom end. From the unit discharge and the depth, and not from measurements of the surface velocity, the Darcy-Weisbach friction coefficient can be calculated. The present results show that this friction coefficient is larger in thin sheet flows than that calculated from the equation for rough turbulent flow. This latter could fit at a Reynolds Number of 50,000. When the regime is laminar (Re < 2,440) the Darcy-Weisbach friction coefficient always exceeds the theoretical value of 96/Re. The great relative depth of standing and travelling waves could account for this discrepancy together with turbulence and wake formation around bottom grains. Herein it is assumed that a regime can prevail where a laminar superlayer glides over a turbulent sublayer in the vicinity of bottom grains, because the ratio of the surface velocity to the mean velocity can greatly exceed 1.5, especially on steep slopes. Until photographs of the streamlines are taken, no statement about flow regimes in supercritical sheet flow can be made.     

The deviation of the total geomagnetic field direction from the dipole field direction as a manifestation of the non-dipole field

Summary The angle between the total geomagnetic field direction and the axial dipole field direction was computed for the whole of the Earth's surface for the epoch 1945. It was supposed that the dipole field exerts a latitude-dependent influence on the surface manifestation of the non-dipole field. A modifying function of latitude was estimated to eliminate this influence. The isolines of the resulting quantity were plotted.     

On mesoscale characteristics of bora conditions in Yugoslavia

The local wind bora is a well-known phenomenon on the eastern coast of the Adriatic Sea, where steep mountains, the Dinaric Alps, closely follow the coast. In a relatively undisturbed atmosphere the coastal thermal effect and the dynamic effect of orography give rise to a cool downslope land breeze, theborino, which develops at night-time, and particularly in the winter season, when the land-sea temperature contrast is large. The causes ofcold bora, with strong and gusty winds, are then attributed to the synoptic scale effects upon the local flow intensification and inland cold air supply. Since the interaction processes on various scale motions are involved in a sequence of bora spells, it is shown how the large scale anomalies may subsequently change the mesoscale characteristics of the bora environment and eventually make the bora appear as a relatively warm wind.     

Tensional crack development in physical models with inhomogeneities under load

Summary The paper deals with a study of the mean stress field (_M) and its gradient (_M/x) in uniaxially loaded two-dimensional models of small thickness with respect to other dimensions, in which two inhomogeneities, e.g., a circular opening and a linear slit have been made. Particular attention was paid to the stress field development in the treated models durin gthe change of the mutual geometric configuration of both the inhomogeneities in question. The problem was analysed theoretically by means of Muskhelishvili's potentials of the two-dimensional theory of elasticity. To compare the results of calculations, the schlieren method was used to visualize and record the studied gradients of stress fields in physical models. The results of the calculations were calibrated by laboratory tests. In this way the individual model situations were classified from the point of view of their resistance to the applied load.     

Ion whistlers in mid-latitude trough of light ions

Summary In the set of VLF data from the Interkosmos-14 satellite (launched on 11 December 1975 with apogee height of 1707 km, perigee 345 km and inclination 74°) as received in direct telemetry transmissions at the Observatory Panská Ves (Czechoslovakia), ion cyclotron whistlers were found at unusually high geomagnetic latitudes. These whistlers indicate a marked decrease of proton density in the close vicinity of the satellite with increasing geomagnetic latitude. It appeared, moreover, that proton whistlers at higher geomagnetic latitudes even sensitively reflected the rapid changes of plasma parameters within the region of the mid-latitude trough of light ions.     

Nitric oxide concentration near the mesopause as deduced from ionospheric absorption measurements

Nitric oxide concentration in the upper D-region is estimated by comparing empirically derived ratios of Lyman- and X-ray contributions to the total radio-wave absorption (2775 kHz. A3 method) in medium latitudes with model ratios. Typical NO concentrations are about 8.5×10¹³ m^–3, at 90 km and 6.5×10¹³ m^–3 at 78 km. These values are higher than generally accepted model NO concentrations, but lie within the broad range of experimental values.     

On the recent dynamics of the earth's surface of the Little Carpathians

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