Towards Bronchoscopic Functional CFTR Assessment using a Short Circuit Current Measurement Probe.

The epithelial lining of luminal organs provides an immune barrier against external factors and regulates transport of nutrients, ions, and water into the body. Several conditions are associated with a breakdown or dysfunction of the epithelial lining. Short circuit current (I) measurement using a bulky, expensive, and hard to deploy system known as the Ussing chamber is the gold standard for evaluation of epithelial transport function but requires tissue excision.

Passively scanned, single-fiber optical coherence tomography probes for gastrointestinal devices.

Background/objectives: Optical coherence tomography (OCT) uses low coherence interferometry to obtain depth-resolved tissue reflectivity profiles (M-mode) and transverse beam scanning to create images of two-dimensional tissue morphology (B-mode). Endoscopic OCT imaging probes typically employ proximal or distal mechanical beam scanning mechanisms that increase cost, complexity, and size. Here, we demonstrate in the gastrointestinal (GI) tracts of unsedated human patients, that a passive, single-fiber probe can be used to guide device placement, conduct device-tissue physical contact sensing, and obtain two-dimensional OCT images via M-to-B-mode conversion.

Minimally Invasive Image-Guided Gut Transport Function Measurement Probe.

Introduction: Diseases such as celiac disease, environmental enteric dysfunction, infectious gastroenteritis, type II diabetes and inflammatory bowel disease are associated with increased gut permeability. Dual sugar absorption tests, such as the lactulose to rhamnose ratio (L:R) test, are the current standard for measuring gut permeability. Although easy to administer in adults, the L:R test has a number of drawbacks.

Improved sensitivity roll-off in dual reference, buffered spectral-domain optical coherence tomography.

Significance: While spectral-domain optical coherence tomography (SD-OCT) is a preferred form of OCT imaging, sensitivity roll-off limits its applicability for certain biomedical imaging applications.

Aim: The aim of this work is to extend the imaging range of conventional SD-OCT systems for imaging large luminal organs such as the gastrointestinal tract.

Approach: We present an SD-OCT system operating at a center wavelength of 1300 nm that uses two delayed reference arms to reduce sensitivity roll-off and an optical switch and a fiber optic delay line to ensure that the interference spectra are acquired from the same sample time window.

Non-endoscopic biopsy techniques: a review.

Diseases of the stomach and small intestine account for approximately 20% of all gastrointestinal (GI)-related mortality. Biopsy of the stomach and small intestine remains a key diagnostic tool for most of the major diseases that affect the GI tract. While endoscopic means for obtaining biopsy is generally the standard of care, it has several limitations that make it less ideal for pediatric patients and in low resource areas of the world.

448 Gbit/s, 32 Gbaud 128 QAM coherent transmission over 150 km with a potential spectral efficiency of 10.7 bit/s/Hz.

We realized a single-carrier, polarization-multiplexed 32 Gbaud 128 QAM coherent transmission. Digital frequency-domain equalization enabled us to achieve waveform distortion compensation of a wideband data signal with high frequency resolution. Thus, we successfully increased the QAM multiplicity to 128 at 32 Gbaud, and transmitted 448 Gbit/s data over 150 km with a potential spectral efficiency of 10.

High-performance TDM demultiplexing of coherent Nyquist pulses using time-domain orthogonality.

We propose a simple and high-performance scheme for demultiplexing coherent Nyquist TDM signals by photo-mixing on a photo-detector with Nyquist LO pulses. This scheme takes advantage of the time-domain orthogonality of Nyquist pulses, which enables high-SNR demultiplexing and homodyne detection simultaneously in spite of a strong overlap with adjacent pulses in the time domain. The feasibility of this scheme is demonstrated through a demultiplexing experiment employing 80 Gbaud, 64 QAM Nyquist pulse OTDM signals.

Single-channel 1.92 Tbit/s, Pol-Mux-64 QAM coherent Nyquist pulse transmission over 150 km with a spectral efficiency of 7.5 bit/s/Hz.

Coherent Nyquist pulses have been used for optical time division multiplexed (OTDM) digital coherent transmission, and a single-channel 1.92 Tbit/s, Pol-Mux-64 QAM coherent Nyquist pulse transmission over 150 km is demonstrated. The ability to considerably reduce the spectral bandwidth of the data signal enabled us to increase the spectral efficiency from 3.

A single-channel 1.92 Tbit/s, 64 QAM coherent optical pulse transmission over 150 km using frequency-domain equalization.

We demonstrate a single-channel 1.92 Tbit/s, 64 QAM coherent optical pulse optical time-division multiplexing (OTDM) transmission by utilizing frequency-domain equalization (FDE). FDE makes it possible to compensate precisely for the waveform distortions caused by hardware imperfections thus greatly improving the error vector magnitude (EVM) of the demodulated 64 QAM signal compared with that obtained with a conventional FIR filter.