Two-particle correlations in azimuthal angle and pseudorapidity in inelastic p + p interactions at the CERN Super Proton Synchrotron

Results on two-particle ΔηΔϕ correlations in inelastic p + p interactions at 20, 31, 40, 80, and 158 GeV/c are presented. The measurements were performed using the large acceptance NA61/SHINE hadron spectrometer at the CERN Super Proton Synchrotron. The data show structures which can be attributed mainly to effects of resonance decays, momentum conservation, and quantum statistics. The results are compared with the Epos and UrQMD models.ISSN:1434-6044ISSN:1434-605

Vertical distribution of mesoplankton at the northern margin of the North Atlantic gyre in June-August 2001

Vertical distribution of mesoplankton was studied over a single season in 2001 at two sites in the western and eastern parts of the northern margin of the North Atlantic gyre. Plankton was sampled both with use of BR 113/140 net and observed from the Mir deep-sea manned submersible. In near-slope waters southeast of Newfoundland (Titanic Polygon) there occurred intensive interaction between subtropical and sub-polar waters and plankton communities. The subtropical gyre community being more mature from the succession viewpoint created a ''net'' of carnivores and scavengers (shrimp and smaller animals) feeding plankton supplied from the north and thus increasing their own biomass. Due to features of hydrological conditions in 2001 in contrast to other years, the plankton supplied from the north was dominated by small copepods, while abundance of larger Calanus hyperboreus was small. Perhaps due to this fact, abundance of macroplanktonic shrimp decreased, while abundance of mesoplanktonic carnivores (Themisto, Sagitta, and Pareuchaeta) increased. In East Atlantic, within the Porcupine abyssal plain (Bismark Polygon) contrasts in frontal boundaries decreased and community interaction became less expressed. While vertical distribution of plankton at Titanic Polygon was characterized by a series of extraordinary features, distribution at Bismark Polygon was much more ordinary

Wet biomass of the main mesoplankton groups in the Guaymas Basin (Gulf of California) measured in October 1990

Plankton above the vent fields of the Guaymas Basin was studied over the entire water column with the use of the MIR deep-sea manned submersible and BR plankton nets. Our studies confirmed that there is a certain increase in zooplankton biomass in the near-bottom layers. A reason for this phenomenon is not clear, but it may be related either to concentration of food particles precipitating from highly-productive surface waters, or to the effect of changes in concentration of dissolved oxygen or to the influence of hydrothermal production. This paper also deals with influence of the oxygen minimum layer at depth of 450-800 m on plankton

Vertical distribution of wet mesozooplankton biomass in areas of three hydrothermal fields in the North Atlantic at night hours

New data on vertical distribution of plankton over hydrothermal fields of the Mid-Atlantic Ridge were obtained. Direct observations from the Mir deep-sea manned submersibles and samplings with use of BR plankton nets allowed to describe for the first time plankton distribution over the Menez Gwen vent field (37°50.5'N). No prominent near-bottom maximum of gelatinous animals was observed. Influence of the upper boundary of the water layer of Mediterranean origin on the vertical distribution of various plankton groups was shown. Distributions of euphausiids and copepods Calanus helgolandicus over the Lost City hydrothermal field (30°07.2'N) is assessed in detail; it is shown that south boreal interzonal species Calanus helgolandicus regularly penetrated up to 30° N

Phyto- and zooplankton of the southeastern Barents Sea in April 2000

Spring bloom of cold-water centric and pennate diatoms was observed in two different areas of the southeastern Barents Sea in April 2000: ice-free waters off the Kolguev Island northern shelf and the eastern Pechora Sea near the Karskie Vorota (Kara Gate) Straight in polynyas and ice-free patches in one-year-old ice. Maximal values of phytoplankton abundance and biomass were found at the ice edge. The bloom was localized in shallow water areas with depths less than 50 m in mixing zones of waters of different origin: warm Atlantic, cold coastal, and Arctic (Litke current) waters. Ice melting was among factors inducing the phytoplankton bloom. Each area had a specific phytocoenosis, whose structure was determined by water origin and ice conditions. In the western Kara Sea, under a solid (up to 30 cm thick) ice cover (i.e., under conditions of a hydrological winter), a spring phytoplankton succession was observed from its initial stage. In areas located close to the ice-cover edge, simultaneously with the mass phytoplankton bloom, the early spring zoocoenosis development manifested itself in mass spawning of euphausiids and mass appearance of Cirripedia nauplii and bottom polychaete larvae