87 research outputs found
Current-induced highly dissipative domains in high Tc thin films
We have investigated the resistive response of high Tc thin films submitted
to a high density of current. For this purpose, current pulses were applied
into bridges made of Nd(1.15)Ba(1.85)Cu3O7 and Bi2Sr2CaCu2O8. By recording the
time dependent voltage, we observe that at a certain critical current j*, a
highly dissipative domain develops somewhere along the bridge. The successive
formation of these domains produces stepped I-V characteristics. We present
evidences that these domains are not regions with a temperature above Tc, as
for hot spots. In fact this phenomenon appears to be analog to the nucleation
of phase-slip centers observed in conventional superconductors near Tc, but
here in contrast they appear in a wide temperature range. Under some
conditions, these domains will propagate and destroy the superconductivity
within the whole sample. We have measured the temperature dependence of j* and
found a similar behavior in the two investigated compounds. This temperature
dependence is just the one expected for the depairing current, but the
amplitude is about 100 times smaller.Comment: 9 pages, 9 figures, Revtex, to appear in Phys. Rev.
Complete Structural Model of Escherichia coli RNA Polymerase from a Hybrid Approach
A combination of structural approaches yields a complete atomic model of the highly biochemically characterized Escherichia coli RNA polymerase, enabling fuller exploitation of E. coli as a model for understanding transcription
Mathematical models for immunology:current state of the art and future research directions
The advances in genetics and biochemistry that have taken place over the last 10Â years led to significant advances in experimental and clinical immunology. In turn, this has led to the development of new mathematical models to investigate qualitatively and quantitatively various open questions in immunology. In this study we present a review of some research areas in mathematical immunology that evolved over the last 10Â years. To this end, we take a step-by-step approach in discussing a range of models derived to study the dynamics of both the innate and immune responses at the molecular, cellular and tissue scales. To emphasise the use of mathematics in modelling in this area, we also review some of the mathematical tools used to investigate these models. Finally, we discuss some future trends in both experimental immunology and mathematical immunology for the upcoming years
The role of RNA polymerase σ subunit in promoter-independent initiation of transcription
In bacteria, initiation of transcription depends on the RNA polymerase σ subunit, which brings catalytically proficient RNA polymerase core to promoters by binding to specific DNA elements located upstream of the transcription start point. Here, we study σ-dependent synthesis of a transcript that is used to prime replication of the single-stranded genome of bacteriophage M13. We show that, in this system, σ plays no role in DNA recognition, which is accomplished solely through RNA polymerase core interaction with DNA downstream of the transcription start point. However, σ is required for full-sized transcript synthesis by allowing RNA polymerase core to escape into productive elongation. RNA polymerase σ may play a similar role during replication primer synthesis in other bacterial mobile elements whose life cycle involves a single-stranded DNA stage
Polyimide/polyoxometalate copolymer thin films: synthesis, thermal and dielectric properties
The economic consequences of wars in the land of Israel in the last hundred years, 1914–2014
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