نتایج جستجو برای: sigma
تعداد نتایج: 23805 فیلتر نتایج به سال:
in proposition 2.6 in (g. gruenhage, a. lutzer, baire and volterra spaces, textit{proc. amer. math. soc.} {128} (2000), no. 10, 3115--3124) a condition that every point of $d$ is $g_delta$ in $x$ was overlooked. so we proved some conditions by which a baire space is equivalent to a volterra space. in this note we show that if $x$ is a monotonically normal $t_1$...
let $m_r$ be a non-zero module and ${mathcal f}: sigma[m_r]times sigma[m_r] rightarrow$ mod-$bbb{z}$ a bifunctor. the $mathcal{f}$-reversibility of $m$ is defined by ${mathcal f}(x,y)=0 rightarrow {mathcal f}(y,x)=0$ for all non-zero $x,y$ in $sigma[m_r]$. hom (resp. rej)-reversibility of $m$ is characterized in different ways. among other things, it is shown th...
in this paper. (1) we determine the complex-valued solutions of the following variant of van vleck's functional equation $$int_{s}f(sigma(y)xt)dmu(t)-int_{s}f(xyt)dmu(t) = 2f(x)f(y), ;x,yin s,$$ where $s$ is a semigroup, $sigma$ is an involutive morphism of $s$, and $mu$ is a complex measure that is linear combinations of dirac measures $(delta_{z_{i}})_{iin i}$, such that for all $iin i$,...
background: sigma factors are proteins that regulate transcription in bacteria. sigma factors can be activated in response to different environmental conditions. the rpos (rna polymerase, sigma s) gene encodes sigma-38 (σ38, or rpos), a 37.8 kda protein in pseudomonas aeruginosa (p. aeruginosa) strains. rpos is a central regulator of the general stress response and operates in both retroactive ...
In this paper, at first for a given set of real or complex numbers $sigma$ with nonnegative summation, we introduce some special conditions that with them there is no nonnegative tridiagonal matrix in which $sigma$ is its spectrum. In continue we present some conditions for existence such nonnegative tridiagonal matrices.
Two sigma factors, sigma 35 and sigma 28, direct transcription from the Bt I and Bt II promoters of the cryIA(a) gene of Bacillus thuringiensis; this gene encodes a lepidopteran-specific crystal protoxin. These sigma factors were biochemically characterized in previous work (K. L. Brown and H. R. Whiteley, Proc. Natl. Acad. Sci. USA 85:4166-4170, 1988; K. L. Brown and H. R. Whiteley, J. Bacteri...
As Bacillus subtilis proceeds through sporulation, the principal vegetative cell sigma subunit (sigma(A)) persists in the cell but is replaced in the extractable RNA polymerase (RNAP) by sporulation-specific sigma factors. To explore how this holoenzyme changeover might occur, velocity centrifugation techniques were used in conjunction with Western blot analyses to monitor the associations of R...
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