No abstract

Computed tomography (CT) is an X-ray-based medical imaging technique commonly used for noninvasive gastrointestinal tract (GIT) imaging. Iodine- and barium-based CT contrast agents are used in the clinic for GIT imaging; however, inflammatory bowel disease (IBD) imaging is challenging since iodinated and barium-based CT agents are not specific for sites of inflammation. Cerium oxide nanoparticles (CeNP) can produce strong X-ray attenuation due to cerium’s k-edge at 40.4 keV but have not yet been explored for CT imaging. In addition, we hypothesized that the use of dextran as a coating material on cerium oxide nanoparticles would encourage accumulation in IBD inflammation sites in a similar fashion to other inflammatory diseases. In this study, therefore, we sought to develop a CT contrast agent, i.e., dextran-coated cerium oxide nanoparticles (Dex-CeNP) for GIT imaging with IBD. We synthesized Dex-CeNP, characterized them using various analytical tools, and examined their in vitro biocompatibility, CT contrast generation, and protective effect against oxidative stress. In vivo CT imaging was done with both healthy mice and a dextran sodium sulfate induced colitis mouse model. Dex-CeNP’s CT contrast generation and accumulation in inflammation sites were compared with iopamidol, an FDA approved CT contrast agent. Dex-CeNP was found to be protective against oxidative damage. Dex-CeNP produced strong CT contrast and accumulated in the colitis area of large intestines. In addition, >97% of oral doses were cleared from the body within 24 h. Therefore, Dex-CeNP can be used as a potential CT contrast agent for imaging GIT with IBD while protecting against oxidative damage.

This paper expands on the previously described reflectionless filters - that is, filters having, in principle, identically-zero reflection coefficient at all frequencies - by introducing a wide variety of new reflectionless structures that were not part of the original publication. In addition to extending the lumped-element derivation to include transmission line filters, this is achieved by the introduction of a novel method wherein the left- and right-hand side stop-band terminations are coupled to each other using a two-port sub-network. Specific examples of the sub-network are given which increase the stop-band attenuation per filter cell and steepen the cutoff response without disrupting the reflectionless property or increasing the insertion-loss in the pass-band. It is noteworthy that a common feature of all the structures derived by these methods is that most, if not all, of the reactive elements are of equal normalized value. This greatly simplifies the tuning requirements, and has facilitated their implementation as monolithic microwave integrated circuits (MMICs). A number of examples of MMIC reflectionless filters constructed in this way are presented and their results compared to the theory.Comment: 9 pages, 20 figure

A new 1.4 GHz 19-element, dual-polarization, cryogenic phased array feed (PAF) radio astronomy receiver has been developed for the Robert C. Byrd Green Bank Telescope (GBT) as part of FLAG (Focal L-band Array for the GBT) project. Commissioning observations of calibrator radio sources show that this receiver has the lowest reported beamformed system temperature (T sys ) normalized by aperture efficiency (η) of any phased array receiver to date. The measured T sys /η is 25.4 ± 2.5 K near 1350 MHz for the boresight beam, which is comparable to the performance of the current 1.4 GHz cryogenic single feed receiver on the GBT. The degradation in T sys /η at ∼ 4 (required for Nyquist sampling) and ∼ 8 offsets from the boresight is, respectively, ∼ 1% and ∼ 20% of the boresight value. The survey speed of the PAF with seven formed beams is larger by a factor between 2.1 and 7 compared to a single beam system depending on the observing application. The measured performance, both in frequency and offset from boresight, qualitatively agree with predictions from a rigorous electromagnetic model of the PAF. The astronomical utility of the receiver is demonstrated by observations of the pulsar B0329+54 and an extended H ii region, the Rosette Nebula. The enhanced survey speed with the new PAF receiver will enable the GBT to carry out exciting new science, such as more efficient observations of diffuse, extended neutral hydrogen emission from galactic in-flows and searches for Fast Radio Bursts.

The aim of this study was to determine the role of body mass index (BMI) in a Western population on outcomes after esophagectomy for cancer. Two hundred and fifteen consecutive patients undergoing esophagectomy for esophageal cancer of any cell type were studied prospectively. Patients with BMIs > 25 kg/m were classified as overweight and compared with control patients with BMIs below these reference values. Ninety-seven patients (45%) had low or normal BMIs, 86 patients (40%) were overweight, and a further 32 (15%) were obese. High BMIs were associated with a higher incidence of adenocarcinoma versus squamous cell carcinoma (83%vs. 14%, P = 0.041). Operative morbidity and mortality were 53% and 3% in overweight patients compared with 49% (P = 0.489) and 8% (P = 0.123) in control patients. Cumulative survival at 5 years was 27% for overweight patients compared with 38% for control patients (P = 0.6896). In a multivariate analysis, age (hazard ratio [HR] 1.492, 95% CI 1.143-1.948, P = 0.003), T-stage (HR 1.459, 95% CI 1.028-2.071, P = 0.034), N-stage (HR 1.815, 95% CI 1.039-3.172, P = 0.036) and the number of lymph node metastases (HR 1.008, 95% CI 1.023-1.158, P = 0.008), were significantly and independently associated with durations of survival. High BMIs were not associated with increased operative risk, and long-term outcomes were similar after R0 esophagectomy.