5 research outputs found
Circular polarization in comets: Observations of Comet C/1999 S4 (LINEAR) and tentative interpretation
Comet C/1999 S4 (LINEAR) was exceptional in many respects. Its nucleus
underwent multiple fragmentations culminating in the complete disruption around
July 20, 2000. We present circular polarization measurements along the cuts
through the coma and nucleus of the comet during three separate observing runs,
in June 28 - July 2, July 8 - 9, and July 21 - 22, 2000. The circular
polarization was detected at a rather high level, up to 0.8%. The left-handed
as well as right-handed polarization was observed over the coma with the left
circularly polarized light systematically observed in the sunward part of the
coma. During our observations the phase angle of the comet varied from 61 up to
122 deg., which allowed us to reveal variations of circular polarization with
the phase angle. Correlation between the degree of circular polarization,
visual magnitude, water production rate, and linear polarization of Comet
C/1999 S4 (LINEAR) during its final fragmentation in July 2000 was found. The
mechanisms that may produce circular polarization in comets and specifically in
Comet C/1999 S4 (LINEAR) are discussed and some tentative interpretation is
presented
The molecular structure of the DNA fragments eliminated during chromatin diminution in Cyclops kolensis
Presumptive somatic cells of the copepod Cyclops kolensis specifically eliminate a large fraction of their genome by the process of chromatin diminution. The eliminated DNA (eDNA) remains only in the germline cells. Very little is known about the nature of the sequences eliminated from somatic cells. We cloned a fraction of the eDNA and sequenced 90 clones that total 32 kb. The following organizational patterns were demonstrated for the eDNA sequences. All do not contain open reading frames. Each fragment contains 1–3 families of short repeats (10–30 bp) highly homologous within families (87%–100%). Most repeats are separated by spacers up to 50 bp long. Homologous regions were found between fragments, motifs from 15–300 bp in length. Among fragments there occur groups in which the same motifs are ordered in the same fashion. However, spacers between the motifs differ in length and nucleotide composition. Ubiquitous motifs (those occurring in all fragments) were identified. Analysis of motifs revealed submotifs, each occurring within several motifs. Thus, motifs may be regarded as mosaic structures composed of submotifs (short repeats). Taken together, the results provide evidence of a high organizational ordering of the DNA sequences restricted to the germline. With this in mind, it appears incorrect to refer to this part of the genome as junk. Moreover, eDNA is redundant for only the somatic cells—its function is to be sought in germline cells
"Flora of Russia" on iNaturalist: a dataset
The "Flora of Russia" project on iNaturalist brought together professional scientists and amateur naturalists from all over the country. Over 10,000 people are involved in the data collection.Within 20 months the participants accumulated over 750,000 photo observations of 6,853 species of the Russian flora. This constitutes the largest dataset of open spatial data on the country’s biodiversity and a leading source of data on the current state of the national flora. About 85% of all project data are available under free licenses (CC0, CC-BY, CC-BY-NC) and can be freely used in scientific, educational and environmental activities
"Flora of Russia" on iNaturalist: a dataset
The "Flora of Russia" project on iNaturalist brought together professional scientists and amateur naturalists from all over the country. Over 10,000 people are involved in the data collection.Within 20 months the participants accumulated over 750,000 photo observations of 6,853 species of the Russian flora. This constitutes the largest dataset of open spatial data on the country’s biodiversity and a leading source of data on the current state of the national flora. About 85% of all project data are available under free licenses (CC0, CC-BY, CC-BY-NC) and can be freely used in scientific, educational and environmental activities
"Flora of Russia" on iNaturalist: a dataset
The "Flora of Russia" project on iNaturalist brought together professional scientists and amateur naturalists from all over the country. Over 10,000 people are involved in the data collection.Within 20 months the participants accumulated over 750,000 photo observations of 6,853 species of the Russian flora. This constitutes the largest dataset of open spatial data on the country’s biodiversity and a leading source of data on the current state of the national flora. About 85% of all project data are available under free licenses (CC0, CC-BY, CC-BY-NC) and can be freely used in scientific, educational and environmental activities