Methodology of Environmental Standardization for Natural Waters

Doklady Earth Sciences - This paper discusses sources of significant errors that occur in the course of determination of the primary environmental standard for natural waters: the maximum...     

Constructing a Stäckel Model of the Galaxy: Solving the Problem of Whether the Vertical Density Distribution Is Realistic

Astronomy Letters - Techniques for solving the problem of constructing a Stäckel model by generalizing the potential from the equatorial plane to the entire space are considered. The initial...     

Causes of rockfalls in Al-Huwayshah area,Yemen

According to topography of Yemen,most areas and villages are located at obligated crest,toe of mountain and under cliffs.Therefore Al-Huwayshah consisting of Tawilah sandstone group is characterized by steep slope reach to 90° in some areas.This area is affected by strong tectonic movements and faults that occurred during the geological epochs.This effect enhances to find out fractures and joints as well as the rocks become brittle and ready to slide depending on the position of area.And there are some frac...     

Analysis of petroleum hydrocarbons in mangrove sediments of Red Sea of Yemen

A field work has been carried out to identify the occurrence of oil and oil products pollution in mangrove sediment from Red Sea of Yemen. The concentration of total petroleum hydrocarbons is from 700ng/g at Kamaran Island station to 400 ng/g at Al-Hodiedah station, and the total organic carbon （TOC） in samples ranges from 0. 07% at Dhubab station to 0. 03% at Kamaran Island station. This pollution is as a result of localized oil pollution and/or heavy ship traffic in the Red Sea and Gulf of Aden.     

Super-Fast Line-Profile Variability in the Spectra of OBA-Stars: B1-Star <Emphasis Type="Italic">ρ</Emphasis> Leo

This study continues our investigation of the super-fast variability of line profiles in the spectra of early-type stars. We have investigated the line-profile variability in spectra of OBA-stars with the SCORPIO multi-mode focal reducer mounted at the 6-m SAO RAS telescope. Regular short-period variations of the H and He lines in the spectra of the B1I star ρ Leo were detected with periods ranging from 2 to 90 minutes, as well as irregular line-profile variations on time intervals less than 1 minute. A possible origin of rapid spectral variations is discussed.     

Estimates of abundance of the short-baseline (1-3 meters) slopes for different Venusian terrains using terrestrial analogues

The interplanetary mission, Venera-D, which is currently being planned, includes a lander. For a successful landing, it is necessary to estimate the frequency distributions of slopes of the Venusian surface at baselines that are comparable with the horizontal dimensions of lander (1–3 m). The available data on the topographic variations on Venus preclude estimates of the frequency of the short-wavelength slopes. In our study, we applied high-resolution digital terrain models (DTM) for specific areas in Iceland to estimate the slopes on Venus. The Iceland DTMs have 0.5 m spatial and 0.1 m vertical resolution. From the set of these DTMs, we have selected those that morphologically resemble typical landscapes on Venus such as tessera, shield, regional, lobate, and smooth plains. The mode of the frequency distribution of slopes on the model tessera terrain is within a 30°–40° range and a fraction of the surface has slopes <7°, which is considered as the upper safety limit. This is the primary interest. The frequency distribution of slopes on the model tessera is not changed significantly as the baseline is changed from 1 m to 3 m. The terrestrial surfaces that model shield and regional plains on Venus have a prominent slope distribution mode between 8°–20° and the fraction of the surfaces with slopes <7° is less than 30% on both 1 m and 3 m baselines. A narrow, left-shifted histogram characterizes the model smooth plains surfaces. The fraction of surfaces with slopes <7° is about 65–75% for the shorter baseline (1 m). At the longer baseline, the fraction of the shallow-sloped surfaces is increased and fraction of the steep slopes is decreased significantly. The fraction of surfaces with slopes <7° for the 3-m baseline is about 75–88% for the terrains that model both lobate and smooth plains.