7,566 research outputs found
Two Dimensional Quantum Chromodynamics as the Limit of Higher Dimensional Theories
We define pure gauge on an infinite strip of width . Techniques
similar to those used in finite allow us to relate -observables to
pure behaviors. The non triviality of the L \arrow 0 limit is proven
and the generalization to four dimensions described. The glueball spectrum of
the theory in the small width limit is calculated and compared to that of the
two dimensional theory.Comment: 12 pages written in LaTeX, figure available from the authors,
preprint Univ. of Valencia, FTUV/94-4
Engineering orthogonal dual transcription factors for multi-input synthetic promoters
Synthetic biology has seen an explosive growth in the capability of engineering artificial gene circuits from transcription factors (TFs), particularly in bacteria. However, most artificial networks still employ the same core set of TFs (for example LacI, TetR and cI). The TFs mostly function via repression and it is difficult to integrate multiple inputs in promoter logic. Here we present to our knowledge the first set of dual activator-repressor switches for orthogonal logic gates, based on bacteriophage λ cI variants and multi-input promoter architectures. Our toolkit contains 12 TFs, flexibly operating as activators, repressors, dual activator–repressors or dual repressor–repressors, on up to 270 synthetic promoters. To engineer non cross-reacting cI variants, we design a new M13 phagemid-based system for the directed evolution of biomolecules. Because cI is used in so many synthetic biology projects, the new set of variants will easily slot into the existing projects of other groups, greatly expanding current engineering capacities
Renormings of
We investigate the best order of smoothness of . We prove in
particular that there exists a -smooth bump function on if
and only if and are both even integers and is a multiple of .Comment: 18 pages; AMS-Te
Scaling-up quantum heat engines efficiently via shortcuts to adiabaticity
The finite-time operation of a quantum heat engine that uses a single
particle as a working medium generally increases the output power at the
expense of inducing friction that lowers the cycle efficiency. We propose to
scale up a quantum heat engine utilizing a many-particle working medium in
combination with the use of shortcuts to adiabaticity to boost the nonadiabatic
performance by eliminating quantum friction and reducing the cycle time. To
this end, we first analyze the finite-time thermodynamics of a quantum Otto
cycle implemented with a quantum fluid confined in a time-dependent harmonic
trap. We show that nonadiabatic effects can be controlled and tailored to match
the adiabatic performance using a variety of shortcuts to adiabaticity. As a
result, the nonadiabatic dynamics of the scaled-up many-particle quantum heat
engine exhibits no friction and the cycle can be run at maximum efficiency with
a tunable output power. We demonstrate our results with a working medium
consisting of particles with inverse-square pairwise interactions, that
includes noninteracting and hard-core bosons as limiting cases.Comment: 15 pages, 3 figures; typo in Eq. (51) fixed. Feature paper in the
Special Issue "Quantum Thermodynamics" edited by Prof. Dr. Ronnie Koslof
- …