Picoflare jets power the solar wind emerging from a coronal hole on the Sun.

Coronal holes are areas on the Sun with open magnetic field lines. They are a source region of the solar wind, but how the wind emerges from coronal holes is not known. We observed a coronal hole using the Extreme Ultraviolet Imager on the Solar Orbiter spacecraft. We identified jets on scales of a few hundred kilometers, which last 20 to 100 seconds and reach speeds of ~100 kilometers per second. The jets are powered by magnetic reconnection and have kinetic energy in the picoflare range. They are intermittent but widespread within the observed coronal hole. We suggest that such picoflare jets could produce enough high-temperature plasma to sustain the solar wind and that the wind emerges from coronal holes as a highly intermittent outflow at small scales.

Ultra-high-resolution observations of persistent null-point reconnection in the solar corona.

Magnetic reconnection is a key mechanism involved in solar eruptions and is also a prime possibility to heat the low corona to millions of degrees. Here, we present ultra-high-resolution extreme ultraviolet observations of persistent null-point reconnection in the corona at a scale of about 390 km over one hour observations of the Extreme-Ultraviolet Imager on board Solar Orbiter spacecraft. The observations show formation of a null-point configuration above a minor positive polarity embedded within a region of dominant negative polarity near a sunspot. The gentle phase of the persistent null-point reconnection is evidenced by sustained point-like high-temperature plasma (about 10 MK) near the null-point and constant outflow blobs not only along the outer spine but also along the fan surface. The blobs appear at a higher frequency than previously observed with an average velocity of about 80 km s-1 and life-times of about 40 s. The null-point reconnection also occurs explosively but only for 4 minutes, its coupling with a mini-filament eruption generates a spiral jet. These results suggest that magnetic reconnection, at previously unresolved scales, proceeds continually in a gentle and/or explosive way to persistently transfer mass and energy to the overlying corona.

Integrated investigations of the electrosurface properties of nonaqueous disperse and capillary systems.

Survey of the experimental results obtained in the Department of Colloid Chemistry of St. Petersburg State University on the integrated investigations of the electrosurface properties of various nonaqueous disperse and capillary systems covering a wide range of electrolyte solutions in various organic solvents: amphoteric ethanol and 1-butanol; dipolar aprotic dimethylsulfoxide, dimethylformamide, acetone and nitromethane; nonpolar n-heptane in contact with SiO2, TiO2, Al2O3 and glass. Electrokinetic potential zeta and charge sigma(zeta), adsorption of ions Gamma, surface conductivity Ks of powdery silica, titania and alumina were determined depending on the concentration 10(-5)-10(-2) M of LiBr, KBr, NaBr, CsBr, HBr, NaCl, NaOH, HCl, various tetraalkylammonium bromides and ionic surfactants in the above cited solvents. Special attention was paid to the consistency of the results of zeta-potential evaluation obtained from the streaming potential and electrophoretic mobility data using the most commonly known theoretical expressions. It was shown that the surface conductivity must be taken into account in all cases for the evaluation of correct zeta-potential values. The surface conductivity and zeta-potential for the porous quartz plugs and glass membranes were determined as the functions of concentration of the anionic surfactants in n-heptane containing controlled traces of water. It was also shown that in the cases of the less polar solvents and more polar solids the enormous values of surface conductivity are due to the adsorption of the traces of water and in the cases of more hydrophylic liquids due to the overall adsorption of all ionic components from the solutions.

[Analysis of new variants of West Nile fever virus]. / Analiz novykh variantov virusa likhoradki Zapadnogo Nila.

The complete nucleotide sequences for 6 strains of the West Nile fever virus were determined. For the first time the complete nucleotide sequences of the Indian isolate and Krsn190 strain, that is the most far phylogenetically from all isolates known at present time were established. The scheme for separation of virus variants into 4 groups and criteria for determination the group to which the isolate belongs are suggested.

[Specific antibodies in convalescents after West Nile fever]. / Pokazateli spetsificheskikh antitel u rekonvalestsentov, perenesshikh likhoradku Zapadnogo Nila.

Blood serum samples were obtained from patients with West Nile fever (WNF) from the city of Volgograd and its region within the disease weeks 1-3 (July-October 1999), month 6-7 (May_June 2000) and month 12-18 (May-June 2001) after the disease onset. In the sera of 40 patients examined 6-7 months after the disease onset IgM-antibodies to WNF virus were absent (dilution 1:50), IgG ones were detected in 35 patients (87.5%). 18 months after the disease IgG-antibodies were identified in 23 of 26 convalescents (88.5%). The serum samples obtained in autumn 1999 and May-June 2000 contained antihemagglutinins to WNF virus for 6-7 months in all 18 patients. In May-June 2000 the sera were positive in 38 convalescents who had WNF in 1999.

Outbreak of West Nile virus infection, Volgograd Region, Russia, 1999.

From July 25 to October 1, 1999, 826 patients were admitted to Volgograd Region, Russia, hospitals with acute aseptic meningoencephalitis, meningitis, or fever consistent with arboviral infection. Of 84 cases of meningoencephalitis, 40 were fatal. Fourteen brain specimens were positive in reverse transcriptase-polymerase chain reaction assays, confirming the presence of West Nile/Kunjin virus.

Isolation of two strains of West Nile virus during an outbreak in southern Russia, 1999.

From July to September 1999, a widespread outbreak of meningoencephalitis associated with West Nile virus (Flavivirus, Flaviviridae) occurred in southern Russia, with hundreds of cases and dozens of deaths. Two strains of West Nile virus isolated from patient serum and brain-tissue samples reacted in hemagglutination-inhibition and neutralization tests with patients' convalescent-phase sera and immune ascites fluid from other strains of West Nile virus.

[Isolation of the West Nile Fever virus from human patients during an epidemic outbreak in the Volgograd and Astrakhan regions]. / Vydelenie virusa likhoradki Zapadnogo Nila ot bol'nykh liudei v periodépidemicheskoi vspyshki v Volgogradskoi i Astrakhanskoi oblastiakh.

Two strains of West Nile virus LEIV 27889 Vig and Ast 986 were isolated from the brain of a dead subject and from the blood of a patient, respectively, during an outbreak of serous meningitis and meningoencephalitis in July-September, 1999, in the Volgograd region, Krasnodar territory, and Astrakhan region. These strains reacted with convalescent sera in hemagglutination inhibition test, which proves their etiological role in this outbreak.

[Epidemic outbreak of meningitis and meningoencephalitis, caused by West Nile virus, in the Krasnodar territory and Volgograd region (preliminary report)]. / Epidemicheskie vxpyshki meningita i meningoéntsefalita v Krasnodarskom krae i Volgogradskoi oblasti, vyzvannye virusom Zapadnogo Nila (Predvaritel'noe soobshchenie).

Sera from 102 inpatients from the Volgograd region (64) and Krasnodar region (38) were tested for antibodies to West Nile (WN) virus in hemagglutination inhibition (HI) test and for IgM and IgG antibodies in enzyme immunoassay (EIA). Diseases etiologically associated with WN virus were diagnosed in 81 patients: in 50 out of 64 in the Volgograd region and in 31 out of 38 in the Krasnodar region, which makes 79.4%. Specificity of antibodies to WN virus was confirmed in HI and EIA with WN antigens, related flaviviruses (Japanese encephalitis and yellow fever), and Sindbis alfavirus. A considerable number and the incidence of WN infection suggest that an epidemic caused by WN virus occurred in the Krasnodar and Volgograd regions in summer 1999.