Macrozooplankton was caught at 17 stations with a Bongo net from the 0-200 m layer. The stations were located near the pack ice edge, between Elephant Islands and the South Orkney Islands. The cluster analysis of 58 recognized taxa allowed to distinguish three regions: the western — near Elephant Island, the middle and the western one — at the South Orkney Islands. No clear difference in macrozooplankton species composition at the open sea stations and those near pack ice was found. The average biomass of macrozooplankton in the investigated area amounted to 82.8 g/1000 m3 (95% CL: 47.2-94.2 g/1000m3). Macrozooplankton was dominated by salps and krill. The biomass and 95% confidence limits were 52.0 g/1000 m3 (15.6-59.2 g/1000 m3) and 26.1 g/1000 m3 (8.4-30.4 g/1000 m3), respectively. Differences in the biomass distribution of some taxa in three distinguished regions were observed. Except of salps the biomass of particular taxa caught near the pack ice edge and the same taxa caught in stations distant from this edge were similar. The biomass of salps was evidently higher in most northern stations.

Total count (TC) of bacteria in drifting annual pack-ice in austral spring fluctuated between 2.8-106 and 2,09-109 dm3. TC of bacteria was lowest in the upper layer of a large pack-ice fragment, emersed above water surface and almost completely free of diatoms; it was comparable to TC of bacteria in surrounding sea water, which was very low at this time (1,92- 106 — 5.8-106 dm -3). TC of bacteria increased in the deeper layers of pack-ice, attaining a maximum in the middle layer characterized by a high count of diatoms. TC of bacteria was highest in small pack-ice pieces 10—20 kg in being and densely overgrown with diatoms. Bacterial population in pack-ice was dominated by rods (62%), and it contained filamentous bacteria (2.4%) and prosthecate forms (4,8%), rarely present in deep sea. Mean volume of bacterial cell (0,206/μm3) was small, only slightly exceeding that of cells of free-living bacteria in sea water in summer.

This paper presents the details of optimized mix design for normal strength and high performance concrete using particle packing method. A critical review of mix design methods have been carried out for normal strength concrete using American Concrete Institute (ACI) and Bureau of Indian Standards (BIS) methods highlighting the similarities and differences towards attaining a particular design compressive strength. Mix design for M30 and M40 grades of concrete have been carried out using ACI, BIS and particle packing methods. Optimization of concrete mix has been carried out by means of particle packing method using EMMA software, which employs modified Anderson curve to adjust the main proportions. Compressive strength is evaluated for the adjusted proportions and it is observed that the mixes designed by particle packing method estimates compressive strength closer to design compressive strength. Further, particle packing method has been employed to optimize the ingredients of high performance concrete and experiments have been carried out to check the design adequacy of the desired concrete compressive strength.

At the northern border of pack ice the study on chlorophyll a content, density of cells, species composition and domination in samples from the drifting ice floes and from brash ice was carried out. 102 taxa of algae were found in the pack ice. In the study area algal taxa were rather uniformly distributed. In different ice layers the qualitative composition of diatom assemblages was similar and usually the diatom Nitzschia cylindrus was dominant and most frequent. Chlorophyll a content (from 0.12 to 334.5 mg m-3) and the density of cells (from 0.3 to 362 x l0 6 cm) varied strongly in various habitats. Ice floes near the northern pack ice border contained low values of chlorophyll a (mean value 0.50 ±0.28 mg m-3) . However, brash sea ice originating from ice floes, contained 142.4 ±117.5 mg m-3 of chlorophyll α in visibly discoloured and 30.1 ±24.3 mg m~3 of chlorophyll α in not visibly discoloured parts on average. The range of chlorophyll α content and the presence of characteristic species allow to distinguish brash sea ice infiltration assemblage of diatoms.

For many years, people’s perceptions of wolves had nothing to do with actual knowledge about wolf biology and ecology. What can close observations of wolf families teach us about these mammals? Should we give wolves names? And why don’t they need our empathy?

This paper discusses the configuration of a space-effective rack cell for storing a given set of heterogeneous items. Rack cells are the primary components of rack storage areas. A rack cell configuration problem (RCCP) for heterogeneous storage is formulated as a combinatorial mathematical model. An effective heuristic for solving the RCCP in practical cases is presented. The proposed heuristic consists of multistage brute force searching of defined sets of feasible solutions and solving linear integer assignment problems by the branch-and-bound method. The developed algorithm was implemented and tested, and the rack cell obtained meets the modularity requirements in the design and operation of heterogeneous storage areas.