Zooplankton community of a small river under abnormal climatic conditions (on the example of the Kazanka river, Russian federation)

© 2015 Begell House, Inc. Global warming is one of the peculiarities of climate changes at the present time. Prolonged periods with abnormally high temperature characterized by the absence of precipitation are responsible for the increase in dissolved solids content and in the degree of contamination. As a consequence, the species richness and numbers of zooplankton decrease, the complex of dominant species and zooplankton structure change, whereas the capability of aquatic ecosystems for self-purification decreases. A gradual restoration of the community is observed during next years. In the small river located within the temperate zone, the period of zooplankton community restoration is about two years

Magnetars as cooling neutron stars with internal heating

We study thermal structure and evolution of magnetars as cooling neutron stars with a phenomenological heat source in a spherical internal layer. We explore the location of this layer as well as the heating rate that could explain high observable thermal luminosities of magnetars and would be consistent with the energy budget of neutron stars. We conclude that the heat source should be located in an outer magnetar's crust, at densities rho < 5e11 g/cm^3, and should have the heat intensity of the order of 1e20 erg/s/cm^3. Otherwise the heat energy is mainly emitted by neutrinos and cannot warm up the surface.Comment: 8 pages, 5 figures, submitted to MNRA

On the angular distribution of extensive air showers

Angular distributions of extensive air showers with different number of charged particles in the range 2.5x10^5--4x10^7 are derived using the experimental data obtained with the EAS MSU array. Possible approximations of the obtained distributions with different empiric functions available in literature, are analysed. It is shown that the exponential function provides the best approximation of the angular distributions in the sense of the chi-squared criterion.Comment: 5 pages including 1 figur

Unstable Nonradial Oscillations on Helium Burning Neutron Stars

Material accreted onto a neutron star can stably burn in steady state only when the accretion rate is high (typically super-Eddington) or if a large flux from the neutron star crust permeates the outer atmosphere. For such situations we have analyzed the stability of nonradial oscillations, finding one unstable mode for pure helium accretion. This is a shallow surface wave which resides in the helium atmosphere above the heavier ashes of the ocean. It is excited by the increase in the nuclear reaction rate during the oscillations, and it grows on the timescale of a second. For a slowly rotating star, this mode has a frequency of approximately 20-30 Hz (for l=1), and we calculate the full spectrum that a rapidly rotating (>>30 Hz) neutron star would support. The short period X-ray binary 4U 1820--30 is accreting helium rich material and is the system most likely to show this unstable mode,especially when it is not exhibiting X-ray bursts. Our discovery of an unstable mode in a thermally stable atmosphere shows that nonradial perturbations have a different stability criterion than the spherically symmetric thermal perturbations that generate type I X-ray bursts.Comment: Accepted for publication in Astrophysical Journal, 22 pages, 14 figure

OPO-laser system for atmospheric sounding in the MID-IR range

A laser system is designed that provides for tunable generation of nanosecond radiation pulses in the 3–4 μm range. Optical block-diagram and specifications of the system are presented. The laser system as a part of a differential absorption lidar designed can be used for remote control of pollutant concentrations along surface atmospheric path

Status of LHC Crab Cavity Cryostat

The complex LHC crab cavity design and the beam-line configuration pose very tight constraints for the cryostat design. An initial assessment of the LHC main RF cryostat points to a new design both from the RF and engineering point of view. The cavity and tunnel constraints are discussed in detail and an initial cryostat design along with the cryogenic circuit is presented