54 research outputs found
On covers of cyclic acts over monoids
In (Bull. Lond. Math. Soc. 33:385β390, 2001) Bican, Bashir and Enochs finally solved a long standing conjecture in module theory that all modules over a unitary ring have a flat cover. The only substantial work on covers of acts over monoids seems to be that of Isbell (Semigroup Forum 2:95β118, 1971), Fountain (Proc. Edinb. Math. Soc. (2) 20:87β93, 1976) and Kilp (Semigroup Forum 53:225β229, 1996) who only consider projective covers. To our knowledge the situation for flat covers of acts has not been addressed and this paper is an attempt to initiate such a study. We consider almost exclusively covers of cyclic acts and restrict our attention to strongly flat and condition (P) covers. We give a necessary and sufficient condition for the existence of such covers and for a monoid to have the property that all its cyclic right acts have a strongly flat cover (resp. (P)-cover). We give numerous classes of monoids that satisfy these conditions and we also show that there are monoids that do not satisfy this condition in the strongly flat case. We give a new necessary and sufficient condition for a cyclic act to have a projective cover and provide a new proof of one of Isbellβs classic results concerning projective covers. We show also that condition (P) covers are not unique, unlike the situation for projective covers
Tabulation, bibliography, and structure of binary intermetallic compounds. I. Compounds of lithium, sodium, potassiu, and rubidium.
The compilation of the material in this report was undertaken to provide a convenient reference source for intermetallic compounds. An adequate bibliography is required for most efficient use. It is in this sense and because of the addition of more compounds that the compilation is considered an extension of the compilation in Smithell\u27s Metals Reference Book
Covers of acts over monoids II
In 1981 Edgar Enochs conjectured that every module has a flat cover and
finally proved this in 2001. Since then a great deal of effort has been spent
on studying different types of covers, for example injective and torsion free
covers. In 2008, Mahmoudi and Renshaw initiated the study of flat covers of
acts over monoids but their definition of cover was slightly different from
that of Enochs. Recently, Bailey and Renshaw produced some preliminary results
on the `other' type of cover and it is this work that is extended in this
paper. We consider free, divisible, torsion free and injective covers and
demonstrate that in some cases the results are quite different from the module
case
Schreier rewriting beyond the classical setting
Using actions of free monoids and free associative algebras, we establish
some Schreier-type formulas involving the ranks of actions and the ranks of
subactions in free actions or Grassmann-type relations for the ranks of
intersections of subactions of free actions. The coset action of the free group
is used to establish the generalization of the Schreier formula to the case of
subgroups of infinite index. We also study and apply large modules over free
associative algebras in the spirit of the paper Olshanskii, A. Yu.; Osin, D.V.,
Large groups and their periodic quotients, Proc. Amer. Math. Soc., 136 (2008),
753 - 759.Comment: 17 page
Π ΠΎΠ»Ρ ΠΌΠ΅ΡΠΈΠ»ΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΏΡΠΎΠΌΠΎΡΠΎΡΠΎΠ² Π³Π΅ΡΠΏΠ΅ΡΠ²ΠΈΡΡΡΠΎΠ² Π² ΡΠ΅Π°Π»ΠΈΠ·Π°ΡΠΈΠΈ ΠΏΠ°ΡΠΎΠ³Π΅Π½Π½ΠΎΠ³ΠΎ ΠΏΠΎΡΠ΅Π½ΡΠΈΠ°Π»Π° Π½Π° ΠΏΡΠΈΠΌΠ΅ΡΠ΅ Π±ΠΎΠ»Π΅Π·Π½ΠΈ ΠΠ°ΡΠ΅ΠΊΠ°
Marekβs disease virus is ubiquitous and can harm not only poultry, but also be oncogenic for humans. VBM and malignant tumors induced by them are a convenient and accessible natural model for studying herpesvirus-associated carcinogenesis. To date, according to our observations, there are additional risks of human infection with the Marekβs disease virus - the disease began to appear in broiler chickens 30 days and older, i.e. contact with poultry meat carries a risk of infection. In addition, COVID-19 disease may be accompanied by folic acid deficiency, i.e. a violation of the folate cycle in humans, which increases the risk of manifestation of diseases associated with DNA viruses, since a violation of the folate cycle can reduce the activity of DNA methylation, incl. viral DNA. Methylation is carried out enzymatically in the first minutes after DNA replication, i.e. postreplicatively. Since the DNA nucleotide sequence does not change, methylation is essentially an epigenetic event. We have studied the relationship between the methylation of promoters of the Marekβs disease virus and the copy number of the virus. The assessment of the presence or absence of methylation, as well as partial methylation, was carried out on the basis of identifying the difference between the threshold cycles dC(t). The presence of unmethylated sites included in the studied promoter sequence was detected on the basis of the ability of methylsensitive restrictases AciI and GlaI. A correlation was found between the concentration of genomic DNA of the Marekβs disease virus serotype 1 strain CVI 988 in cell culture and the presence of demethylated CpG islands in the composition of promoters located at position 9413-9865 bp. and 127943 - 128193 b.p. genomic DNA of the virus. The data obtained make it possible to explain the mechanism of the increase in the pathogenicity of herpesvirus infections under conditions of a decrease in the activity of viral DNA methylation in the body.ΠΠΈΡΡΡ Π±ΠΎΠ»Π΅Π·Π½ΠΈ ΠΠ°ΡΠ΅ΠΊΠ° (ΠΠΠ) ΠΈΠΌΠ΅Π΅Ρ ΠΏΠΎΠ²ΡΠ΅ΠΌΠ΅ΡΡΠ½ΠΎΠ΅ ΡΠ°ΡΠΏΡΠΎΡΡΡΠ°Π½Π΅Π½ΠΈΠ΅ ΠΈ ΠΌΠΎΠΆΠ΅Ρ Π½Π΅ ΡΠΎΠ»ΡΠΊΠΎ Π½Π°Π½ΠΎΡΠΈΡΡ Π²ΡΠ΅Π΄ Π΄ΠΎΠΌΠ°ΡΠ½Π΅ΠΉ ΠΏΡΠΈΡΠ΅, Π½ΠΎ ΠΈ ΠΎΠ±Π»Π°Π΄Π°ΡΡ ΠΎΠ½ΠΊΠΎΠ³Π΅Π½Π½ΠΎΡΡΡΡ Π΄Π»Ρ ΡΠ΅Π»ΠΎΠ²Π΅ΠΊΠ°. ΠΠΠ ΠΈ ΠΈΠ½Π΄ΡΡΠΈΡΡΠ΅ΠΌΡΠ΅ ΠΈΠΌΠΈ Π·Π»ΠΎΠΊΠ°ΡΠ΅ΡΡΠ²Π΅Π½Π½ΡΠ΅ ΠΎΠΏΡΡ
ΠΎΠ»ΠΈ ΡΠ²Π»ΡΡΡΡΡ ΡΠ΄ΠΎΠ±Π½ΠΎΠΉ ΠΈ Π΄ΠΎΡΡΡΠΏΠ½ΠΎΠΉ Π΅ΡΡΠ΅ΡΡΠ²Π΅Π½Π½ΠΎΠΉ ΠΌΠΎΠ΄Π΅Π»ΡΡ ΠΈΠ·ΡΡΠ΅Π½ΠΈΡ ΠΊΠ°Π½ΡΠ΅ΡΠΎΠ³Π΅Π½Π΅Π·Π°, Π°ΡΡΠΎΡΠΈΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ Ρ Π³Π΅ΡΠΏΠ΅ΡΠ²ΠΈΡΡΡΠ°ΠΌΠΈ. ΠΠ° ΡΠ΅Π³ΠΎΠ΄Π½ΡΡΠ½ΠΈΠΉ Π΄Π΅Π½Ρ, ΠΏΠΎ Π½Π°ΡΠΈΠΌ Π½Π°Π±Π»ΡΠ΄Π΅Π½ΠΈΡΠΌ, ΠΏΠΎΡΠ²ΠΈΠ»ΠΈΡΡ Π΄ΠΎΠΏΠΎΠ»Π½ΠΈΡΠ΅Π»ΡΠ½ΡΠ΅ ΡΠΈΡΠΊΠΈ Π·Π°ΡΠ°ΠΆΠ΅Π½ΠΈΡ Π»ΡΠ΄Π΅ΠΉ Π²ΠΈΡΡΡΠΎΠΌ Π±ΠΎΠ»Π΅Π·Π½ΠΈ ΠΠ°ΡΠ΅ΠΊΠ° β Π±ΠΎΠ»Π΅Π·Π½Ρ Π½Π°ΡΠ°Π»Π° ΠΏΠΎΡΠ²Π»ΡΡΡΡΡ Ρ ΡΡΠΏΠ»ΡΡ-Π±ΡΠΎΠΉΠ»Π΅ΡΠΎΠ² 30 Π΄Π½Π΅ΠΉ ΠΈ ΡΡΠ°ΡΡΠ΅, Ρ.Π΅. ΠΊΠΎΠ½ΡΠ°ΠΊΡ Ρ ΠΌΡΡΠΎΠΌ ΠΏΡΠΈΡΡ Π½Π΅ΡΠ΅Ρ ΡΠΈΡΠΊ Π·Π°ΡΠ°ΠΆΠ΅Π½ΠΈΡ. ΠΠΎΠΌΠΈΠΌΠΎ ΡΡΠΎΠ³ΠΎ, Π·Π°Π±ΠΎΠ»Π΅Π²Π°Π½ΠΈΠ΅ COVID-19 ΠΌΠΎΠΆΠ΅Ρ ΡΠΎΠΏΡΠΎΠ²ΠΎΠΆΠ΄Π°ΡΡΡΡ Π΄Π΅ΡΠΈΡΠΈΡΠΎΠΌ ΡΠΎΠ»ΠΈΠ΅Π²ΠΎΠΉ ΠΊΠΈΡΠ»ΠΎΡΡ, Ρ.Π΅. Π½Π°ΡΡΡΠ΅Π½ΠΈΠ΅ΠΌ ΡΠΎΠ»Π°ΡΠ½ΠΎΠ³ΠΎ ΡΠΈΠΊΠ»Π° Ρ Π»ΡΠ΄Π΅ΠΉ, ΡΡΠΎ ΠΏΠΎΠ²ΡΡΠ°Π΅Ρ ΡΠΈΡΠΊ ΠΌΠ°Π½ΠΈΡΠ΅ΡΡΠ°ΡΠΈΠΈ Π·Π°Π±ΠΎΠ»Π΅Π²Π°Π½ΠΈΠΉ, ΡΠ²ΡΠ·Π°Π½Π½ΡΡ
Ρ ΠΠΠ-Π²ΠΈΡΡΡΠ°ΠΌΠΈ, ΡΠ°ΠΊ ΠΊΠ°ΠΊ Π½Π°ΡΡΡΠ΅Π½ΠΈΠ΅ ΡΠΎΠ»Π°ΡΠ½ΠΎΠ³ΠΎ ΡΠΈΠΊΠ»Π° ΡΠΏΠΎΡΠΎΠ±Π½ΠΎ ΡΠ½ΠΈΠ·ΠΈΡΡ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ ΠΌΠ΅ΡΠΈΠ»ΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΠΠ, Π² Ρ.Ρ. Π²ΠΈΡΡΡΠ½ΠΎΠΉ ΠΠΠ. ΠΠ΅ΡΠΈΠ»ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ ΠΎΡΡΡΠ΅ΡΡΠ²Π»ΡΠ΅ΡΡΡ ΡΠ΅ΡΠΌΠ΅Π½ΡΠ°ΡΠΈΠ²Π½ΠΎ Π² ΠΏΠ΅ΡΠ²ΡΠ΅ ΠΌΠΈΠ½ΡΡΡ ΠΏΠΎΡΠ»Π΅ ΡΠ΅ΠΏΠ»ΠΈΠΊΠ°ΡΠΈΠΈ ΠΠΠ, Ρ.Π΅. ΠΏΠΎΡΡΡΠ΅ΠΏΠ»ΠΈΠΊΠ°ΡΠΈΠ²Π½ΠΎ. ΠΠΎΡΠΊΠΎΠ»ΡΠΊΡ Π½ΡΠΊΠ»Π΅ΠΎΡΠΈΠ΄Π½Π°Ρ ΠΏΠΎΡΠ»Π΅Π΄ΠΎΠ²Π°ΡΠ΅Π»ΡΠ½ΠΎΡΡΡ ΠΠΠ ΠΏΡΠΈ ΡΡΠΎΠΌ Π½Π΅ ΠΌΠ΅Π½ΡΠ΅ΡΡΡ, ΠΌΠ΅ΡΠΈΠ»ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ ΠΏΠΎ ΡΡΡΠΈ ΡΠ²ΠΎΠ΅ΠΉ β ΡΠΎΠ±ΡΡΠΈΠ΅ ΡΠΏΠΈΠ³Π΅Π½Π΅ΡΠΈΡΠ΅ΡΠΊΠΎΠ΅. ΠΠ°ΠΌΠΈ Π±ΡΠ»Π° ΠΈΠ·ΡΡΠ΅Π½Π° Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΡ ΠΌΠ΅ΠΆΠ΄Ρ ΠΌΠ΅ΡΠΈΠ»ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΠΏΡΠΎΠΌΠΎΡΠΎΡΠΎΠ² Π²ΠΈΡΡΡΠ° Π±ΠΎΠ»Π΅Π·Π½ΠΈ ΠΠ°ΡΠ΅ΠΊΠ° ΠΈ ΠΊΠΎΠΏΠΈΠΉΠ½ΠΎΡΡΡΡ Π²ΠΈΡΡΡΠ°. ΠΡΠ΅Π½ΠΊΠ° Π½Π°Π»ΠΈΡΠΈΡ ΠΈΠ»ΠΈ ΠΎΡΡΡΡΡΡΠ²ΠΈΡ ΠΌΠ΅ΡΠΈΠ»ΠΈΡΠΎΠ²Π°Π½ΠΈΡ, ΡΠ°ΠΊ ΠΆΠ΅ ΠΊΠ°ΠΊ ΠΈ ΡΠ°ΡΡΠΈΡΠ½ΠΎΠ³ΠΎ ΠΌΠ΅ΡΠΈΠ»ΠΈΡΠΎΠ²Π°Π½ΠΈΡ, ΠΎΡΡΡΠ΅ΡΡΠ²Π»ΡΠ»Π°ΡΡ Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ Π²ΡΡΠ²Π»Π΅Π½ΠΈΡ ΡΠ°Π·Π½ΠΈΡΡ ΠΌΠ΅ΠΆΠ΄Ρ ΠΏΠΎΡΠΎΠ³ΠΎΠ²ΡΠΌΠΈ ΡΠΈΠΊΠ»Π°ΠΌΠΈ dC(t). ΠΠ°Π»ΠΈΡΠΈΠ΅ Π½Π΅ΠΌΠ΅ΡΠΈΠ»ΠΈΡΠΎΠ²Π°Π½Π½ΡΡ
ΡΠ°ΠΉΡΠΎΠ², Π²Ρ
ΠΎΠ΄ΡΡΠΈΡ
Π² ΡΠΎΡΡΠ°Π² ΠΈΠ·ΡΡΠ°Π΅ΠΌΠΎΠΉ ΠΏΡΠΎΠΌΠΎΡΠΎΡΠ½ΠΎΠΉ ΠΏΠΎΡΠ»Π΅Π΄ΠΎΠ²Π°ΡΠ΅Π»ΡΠ½ΠΎΡΡΠΈ, Π²ΡΡΠ²Π»ΡΠ»ΠΎΡΡ Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΡΠΏΠΎΡΠΎΠ±Π½ΠΎΡΡΠΈ ΠΌΠ΅ΡΠΈΠ»ΡΡΠ²ΡΡΠ²ΠΈΡΠ΅Π»ΡΠ½ΡΡ
ΡΠ΅ΡΡΡΠΈΠΊΡΠ°Π· AciI ΠΈ GlaI. ΠΡΠ»Π° ΠΎΠ±Π½Π°ΡΡΠΆΠ΅Π½Π° ΠΊΠΎΡΡΠ΅Π»ΡΡΠΈΠΎΠ½Π½Π°Ρ Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΡ ΠΌΠ΅ΠΆΠ΄Ρ ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠ°ΡΠΈΠ΅ΠΉ Π³Π΅Π½ΠΎΠΌΠ½ΠΎΠΉ ΠΠΠ Π²ΠΈΡΡΡΠ° Π±ΠΎΠ»Π΅Π·Π½ΠΈ ΠΠ°ΡΠ΅ΠΊΠ° 1-Π³ΠΎ ΡΠ΅ΡΠΎΡΠΈΠΏΠ° ΡΡΠ°ΠΌΠΌΠ° CVI988 Π² ΠΊΡΠ»ΡΡΡΡΠ΅ ΠΊΠ»Π΅ΡΠΎΠΊ ΠΈ Π½Π°Π»ΠΈΡΠΈΠ΅ΠΌ Π΄Π΅ΠΌΠ΅ΡΠΈΠ»ΠΈΡΠΎΠ²Π°Π½Π½ΡΡ
CpG-ΠΎΡΡΡΠΎΠ²ΠΊΠΎΠ² Π² ΡΠΎΡΡΠ°Π²Π΅ ΠΏΡΠΎΠΌΠΎΡΠΎΡΠΎΠ², Π»ΠΎΠΊΠ°Π»ΠΈΠ·ΡΡΡΠΈΡ
ΡΡ Π² ΠΏΠΎΠ»ΠΎΠΆΠ΅Π½ΠΈΠΈ 9413β9865 ΠΈ 127943β128193 ΠΏ.Π½. Π³Π΅Π½ΠΎΠΌΠ½ΠΎΠΉ ΠΠΠ Π²ΠΈΡΡΡΠ°. ΠΠΎΠ»ΡΡΠ΅Π½Π½ΡΠ΅ Π΄Π°Π½Π½ΡΠ΅ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΡΡ ΠΎΠ±ΡΡΡΠ½ΠΈΡΡ ΠΌΠ΅Ρ
Π°Π½ΠΈΠ·ΠΌ ΠΏΠΎΠ²ΡΡΠ΅Π½ΠΈΡ ΠΏΠ°ΡΠΎΠ³Π΅Π½Π½ΠΎΡΡΠΈ Π³Π΅ΡΠΏΠ΅ΡΠ²ΠΈΡΡΡΠ½ΡΡ
ΠΈΠ½ΡΠ΅ΠΊΡΠΈΠΉ Π² ΡΡΠ»ΠΎΠ²ΠΈΡΡ
ΡΠ½ΠΈΠΆΠ΅Π½ΠΈΡ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ ΠΌΠ΅ΡΠΈΠ»ΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π²ΠΈΡΡΡΠ½ΠΎΠΉ ΠΠΠ Π² ΠΎΡΠ³Π°Π½ΠΈΠ·ΠΌΠ΅
Tabulation, bibliography, and structure of binary intermetallic compounds. I. Compounds of lithium, sodium, potassiu, and rubidium.
The compilation of the material in this report was undertaken to provide a convenient reference source for intermetallic compounds. An adequate bibliography is required for most efficient use. It is in this sense and because of the addition of more compounds that the compilation is considered an extension of the compilation in Smithell's "Metals Reference Book."</p
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