2,249 research outputs found
Time-programmable drug dosing allows the manipulation, suppression and reversal of antibiotic drug resistance in vitro
Multi-drug strategies have been attempted to prolong the efficacy of existing antibiotics, but with limited success. Here we show that the evolution of multi-drug-resistant Escherichia coli can be manipulated in vitro by administering pairs of antibiotics and switching between them in ON/OFF manner. Using a multiplexed cell culture system, we find that switching between certain combinations of antibiotics completely suppresses the development of resistance to one of the antibiotics. Using this data, we develop a simple deterministic model, which allows us to predict the fate of multi-drug evolution in this system. Furthermore, we are able to reverse established drug resistance based on the model prediction by modulating antibiotic selection stresses. Our results support the idea that the development of antibiotic resistance may be potentially controlled via continuous switching of drugs
Remarks on the light ring images and the optical appearance of hairy black holes in Einstein-Maxwell-dilaton gravity
The behaviors of null geodesics in the spherical symmetric black holes in
Einstein-Maxwell-dilaton (EMD) theory with coupling function
are meticulously analyzed. We investigate the
effects of coupling constant on the effective potential of photon
trajectories within three ranges, namely , and . We find that the thicknesses of lensing and photon rings are smaller at
larger and fixed electric charge in the unit of mass , whereas they
are larger at fixed and larger . Remarkably, the behaviors of
photon trajectories are found to be more interesting when . Namely,
the radius of the black hole shadow becomes to be smaller than the
photon sphere radius when and . Moreover,
goes to zero as saturates the extremal limit, beyond which the
photon orbit becomes absent. %This tends to be consistent with the result of
Wilczek. Furthermore, we construct the optical appearance of black holes
surrounded by optically and geometrically thin accretion disks with three
emission models. Our results indicate that the observed flux originating from
the lensing and photon rings exhibits suppression as increases, while
it undergoes amplification with the increasing parameter
- …