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...

Coordinated observations of the galactic center region using the imaging SIGMA instrument and the high-sensitivity OSSE instrument were performed to separate the compact source contributions from the diiuse component. The resulting compact-source corrected spectrum of the galactic center region is found to be similar in both intensity and spectral index to the spectra obtained from OSSE observa...

The reduced scattering cross section per unit of volume Sigma'(s) identical withSigma(s)(1 - g) is an important parameter to describe light propagation in media with scattering and absorption. Mie calculations of the asymmetry factor g for nonabsorbing spheres and Q(sca), the ratio of the scattering cross section Sigma(s) and the particle cross section, show that Q(sca)(1 - g) = 3.28x(0.37)(m -...

SLX 1735−269 is among the 10 persistent, high energy, SIGMA sources which contribute significantly to the last five year averaged γ/X-ray emission from the direction of the Galactic Center. Detailed study of the source has only been carried out recently from data collected by SIGMA in the 35-150 keV range without successfully establishing the nature of SLX 1735−269, consequently observations wi...

We find a general class of nontrivial stationary states in inelastic gases where, due to dissipation, energy is transferred from large velocity scales to small velocity scales. These steady states exist for arbitrary collision rules and arbitrary dimension. Their signature is a stationary velocity distribution f(v) with an algebraic high-energy tail, f(v) approximately v(-sigma). The exponent s...

An all-digital PWM-based delta-sigma (ΔΣ) ADC is proposed. This system takes advantages of the duration of a pulse, rather than voltage or current, as the analog operand used in its closed-loop operation. Unlike VCO-based ADCs, this ADC as a linear input sampling stage with adequate uncalibrated performance. Furthermore, the architecture allows inherently matched multi-bit quantizer/DAC blocks ...