Plasmid topology varies transiently in hyperthermophilic archaea during thermal stress. As in mesophilic bacteria, DNA linking number (Lk) increases during heat shock and decreases during cold shock. Despite this correspondence, plasmid DNA topology and proteins presumably involved in DNA topological control in each case are different. Plasmid DNA in hyperthermophilic archaea is found in a topo...

Transformation of Escherichia coli plays an important role in recombinant DNA technology. Most current transformation protocols require that the cells be treated to attain a particular physiological state known as "competence," and this makes transformation procedures lengthy and arduous. Here we describe a protocol for transforming log-phase E. coli using dimethyl sulfoxide (DMSO) solutions of...

The current study was undertaken to investigate the expression of stress proteins (HSP) in cultured human HT29 cells submitted to stressing events under in vitro conditions. Heat shocks (45 degrees C, for 15-60 min) or cold shocks (+ 1 degree C for 4 hr) were found to modify cell growth (growth curves) and to enhance HSP expression. In most cases, changes in HSP expression are much more pronoun...

Shock waves in plasma are usually dealt with using magnetohydrodynamics (MHD). Yet, MHD entails the assumption of a short mean free path, which is not fulfilled collisionless plasma. Recently, for pair plasmas, we devised model allowing one to account kinetic effects within MHD-like formalism. Its relies on an estimate anisotropy generated when crossing front, subsequent assessment stability th...

We have performed hydrodynamic simulations of galaxy formation in a cold dark matter (ΛCDM) universe. We have followed galaxy formation in a dark matter halo, chosen to have a relatively quiet recent merger history, using different models for star formation and feedback. In all cases, we have adopted a multi-phase description of the interstellar medium and modelled star formation in quiescent a...

We present Smoothed Particle Hydrodynamics (SPH) simulations of molecular cloud formation in spiral galaxies. These simulations model the response of a non-selfgravitating gaseous disk to a galactic potential. The spiral shock induces high densities in the gas, and considerable structure in the spiral arms, which we identify as molecular clouds. We regard the formation of these structures as du...

We have observed the IRDC G028.23-00.19 at 3.3 mm using CARMA. In its center, the IRDC hosts one of the most massive (∼1520 M ) quiescent, cold (12 K) clumps known (MM1). The low temperature, high NH2D abundance, narrow molecular linewidths, and absence of embedded IR sources (from 3.6 to 70 μm) indicate that the clump is likely prestellar. Strong SiO emission with broad linewidths (6-9 km s−1)...

Many explanations of the stylized facts concerning real exchange rate movements focus on monetary shocks, but it is often found empirically that monetary shocks are unimportant. I provide evidence that is contrary to this empirical finding. Using over 100 years of data, I estimate the contribution of various shocks to explaining variation in the real pound-dollar exchange rate. Monetary shocks ...

ABSTRACT We study the formation and evolution of jets in solar atmosphere using numerical simulations partially ionized plasma. The two-fluid magnetohydrodynamic equations with ion+electron neutral hydrogen components are used two-dimensional Cartesian geometry. Numerical show that a localized non-linear Gaussian pulse ion pressures initially launched from magnetic null point potential arcade l...

Energetic electromagnetic emissions by astrophysical jets like those that are launched during the collapse of amassive star and trigger gamma-ray bursts are partially attributed to relativistic internal shocks. The shocks are mediated in the collisionless plasma of such jets by the filamentation instability of counterstreaming particle beams. The filamentation instability grows fastest only if ...