20 research outputs found
Quantum-limited directional amplifiers with optomechanics
Directional amplifiers are an important resource in quantum information
processing, as they protect sensitive quantum systems from excess noise. Here,
we propose an implementation of phase-preserving and phase-sensitive
directional amplifiers for microwave signals in an electromechanical setup
comprising two microwave cavities and two mechanical resonators. We show that
both can reach their respective quantum limits on added noise. In the reverse
direction, they emit thermal noise stemming from the mechanical resonators and
we discuss how this noise can be suppressed, a crucial aspect for technological
applications. The isolation bandwidth in both is of the order of the mechanical
linewidth divided by the amplitude gain. We derive the bandwidth and
gain-bandwidth product for both and find that the phase-sensitive amplifier has
an unlimited gain-bandwidth product. Our study represents an important step
toward flexible, on-chip integrated nonreciprocal amplifiers of microwave
signals
Does CDX2 expression predict Barrett's metaplasia in oesophageal columnar epithelium without goblet cells?
Background: Intestinal metaplasia (Barrett's oesophagus), but not cardiac-type mucosa in columnar-lined oesophagus, is regarded as premalignant. As intestinal metaplasia and cardiac-type mucosa are endoscopically indiscernible, it is difficult to take targeted samples from columnar-lined oesophagus with consequently a risk of having undetected intestinal metaplasia. Aim: To investigate whether the intestinal markers CDX2, MUC2 and villin can predict the presence of undetected intestinal metaplasia in columnar-lined oesophagus. Methods: Presence of intestinal metaplasia or cardiac-type mucosa was identified in 122 biopsy sets of columnar-lined oesophagus from 61 patients, collected at two subsequent follow-up upper endoscopies. CDX2, MUC2 and villin expression were determined by immunohistochemistry. Results: All intestinal metaplasia samples (55) were positive for CDX2 and MUC2 and 32 of 55 for vil
Odorous Products of the Chlorination of Phenylalanine in Water: Formation, Evolution, and Quantification
International audienc