Electron transport and optical properties of shallow GaAs/InGaAs/GaAs quantum wells with a thin central AlAs barrier

Shallow GaAs/InGaAs/GaAs quantum well structures with and without a three monolayer thick AlAs central barrier have been investigated for different well widths and Si doping levels. The transport parameters are determined by resistivity measurements in the temperature range 4-300 K and magnetotransport in magnetic fields up to 12 T. The (subband) carrier concentrations and mobilities are extracted from the Hall data and Shubnikov-de Haas oscillations. We find that the transport parameters are strongly affected by the insertion of the AlAs central barrier. Photoluminescence spectra, measured at 77 K, show an increase of the transition energies upon insertion of the barrier. The transport and optical data are analyzed with help of self-consistent calculations of the subband structure and envelope wave functions. Insertion of the AlAs central barrier changes the spatial distribution of the electron wave functions and leads to the formation of hybrid states, i.e. states which extend over the InGaAs and the delta-doped layer quantum wells.Comment: 14 pages, pdf fil

Results of Application of the New Nutrient Media Set for Cholera Diagnostics within the Frames of the Special Tactical Training Exercises for Specialized Anti-Epidemic Team

Carried out is approbation of the new nutrient media set for cholera diagnostics on the basis of bakers' yeast pancreatic digest within the frames of the special tactical training exercises for specialized anti-epidemic team (SAET). It is demonstrated that the developed nutrient media set compare favourably with its analogues, commonly used for practical procedures; and its constituent media have a potential to be included into the SAET mobilization reserve

West Nile Fever in the Rostov Region: Ecological and Epidemiological Peculiarities of the Outbreak in 2010

This paper describes the outbreak of West Nile fever in the Rostov Region in 2010 and evaluates its ecological and epidemiological peculiarities. From 15th of July till 22nd of September 2010, detected were the 64 cases (1, 4800/0000) of the disease, which were characterized by vector-born mechanism of transmission. Peak of morbidity coincided with mass breeding of Culicidae, increase in the number of Culex mosquitoes, and reoccurring growth of Aedes mosquito population. Diffuse type of the epidemiological process, higher rates of the cases among urbanites, infected in the country-side area, were the characteristic features of that outbreak. West Nile virus antigen was detected by means of IFA in samples taken from An. maculipennis and Cx. pipiens mosquitoes, wild and synanthropic birds, Rh. rossicus ticks, house and wood mice, which facilitates identification of the core factors for the agent circulation and West Nile fever natural focus formation

Epidemiologic Situation on Cholera in the World, CIS Countries and Russia. Prognosis

Epidemiologic situation on cholera in the world, CIS countries and Russia has been evaluated for the period of 2000-2009. The last decade (2000-2009) is characterized by the on-going large epidemics and outbreaks of cholera in the countries of Africa and Asia. Unfavorable epidemiologic situation in the world is worsened by intercontinental, inter- and intrastate importation of the infection. Since 2000 more than 960 imported cases of cholera have been registered in the world including 222 cases in the European countries. Epidemiologic situation in CIS countries and Russia is evaluated as unstable due to the registered imported cases and annual isolation of Vibrio cholerae O1 and O139 from the environment. The cholera prognosis for Russia remains unfavorable

Assessment of Cholera Epidemiological Situation in the World in the Present Period. Prognosis

In the first decade of the XXI century large-scale cholera epidemics and outbreaks were registered in African, Asian, and North American countries. Importation of infection from endemic foci to all continents took place almost every year, and the tendency of global cholera morbidity growth was observed. All that determined unfavorable prognosis on cholera at the global level. Cholera epidemic in the Caribbean Basin region, Haiti, caused by V.cholerae El Tor harboring cholera toxin ctxB gene of classical biovar is expected to predetermine either the beginning of a new period of the seventh pandemic or the onset of new pandemic