Ulcerative Colitis: Rapid Evidence Review.

Ulcerative colitis is a relapsing and remitting inflammatory bowel disease of the large intestine. Risk factors include recent Salmonella or Campylobacter infection and a family history of ulcerative colitis. Diagnosis is suspected based on symptoms of urgency, tenesmus, and hematochezia and is confirmed with endoscopic findings of continuous inflammation from the rectum to more proximal colon, depending on the extent of disease.

Frequency-resolved optical gating and single-shot spectral measurements reveal fine structure in microstructure-fiber continuum.

Cross-correlation frequency-resolved optical gating with an angle-dithered nonlinear-optical crystal permits measurement of the intensity and the phase of the ultrabroadband (as much as 1200 nm wide) continuum generated from microstructure optical fiber. Retrieval revealed fine-scale structure in the continuum spectrum. Simulations and single-shot spectrum measurements confirmed that the fine structure does exist on a single-shot basis but washes out when many shots are averaged.

Crossed-beam spectral interferometry: a simple, high-spectral-resolution method for completely characterizing complex ultrashort pulses in real time.

We present a high-spectral-resolution and experimentally simple version of spectral interferometry using optical fibers and crossed beams, which we call SEA TADPOLE. Rather than using collinear unknown and reference pulses separated in time to yield spectral fringes-and reduced spectral resolution-as in current versions, we use time-coincident pulses crossed at a small angle to generate spatial fringes. This allows the extraction of the spectral phase with the full spectrometer resolution, which allows the measurement of much longer and more complex pulses.

Experimental studies of the coherence of microstructure-fiber supercontinuum.

The phase coherence of supercontinuum generation in microstructure fiber is quantified by performing a Young's type interference experiment between independently generated supercontinua from two separate fiber segments. Analysis of the resulting interferogram yields the wavelength dependence of the magnitude of the mutual degree of coherence, and a comparison of experimental results with numerical simulations suggests that the primary source of coherence degradation is the technical noise-induced fluctuations in the injected peak power.

Measurement of the intensity and phase of attojoule femtosecond light pulses using Optical-Parametric-Amplification Cross-Correlation Frequency-Resolved Optical Gating.

We use the combination of ultrafast gating and high parametric gain available with Difference-Frequency Generation (DFG) and Optical Parametric Amplification (OPA) to achieve the complete measurement of ultraweak ultrashort light pulses. Specifically, spectrally resolving such an amplified gated pulse vs. relative delay yields the complete pulse intensity and phase vs.