A 3D-printed broadband millimeter wave absorber

We present the design, manufacturing technique, and characterization of a 3D-printed broadband graded index millimeter wave absorber. The absorber is additively manufactured using a fused filament fabrication (FFF) 3D printer out of a carbon-loaded high impact polystyrene (HIPS) filament and is designed using a space-filling curve to optimize manufacturability using said process. The absorber's reflectivity is measured from 63 GHz to 115 GHz and from 140 GHz to 215 GHz and is compared to electromagnetic simulations. The intended application is for terminating stray light in Cosmic Microwave Background (CMB) telescopes, and the absorber has been shown to survive cryogenic thermal cycling.Comment: 6 pages, 6 figures, 2 tables, accepted to Review of Scientific Instrument

Robotic partial nephrectomy for posterior tumors through a retroperitoneal approach offers decreased length of stay compared with the transperitoneal approach: A propensity-matched analysis

INTRODUCTION: We sought to compare surgical outcomes between transperitoneal and retroperitoneal robotic partial nephrectomy (RPN) for posterior tumors. PATIENTS AND METHODS: Using our multi-institutional RPN database, we reviewed 610 consecutive cases for posterior renal masses treated between 2007 and 2015. Primary outcomes were complications, operative time, length of stay (LOS), surgical margin status, and estimated glomerular filtration rate (eGFR) preservation. Secondary outcomes were estimated blood loss, warm ischemia time (WIT), disease recurrence, and disease-specific mortality. Due to significant differences in treatment year and tumor size between approaches, retroperitoneal cases were matched 1:4 to transperitoneal cases based on propensity scores using the greedy algorithm. Outcomes were compared between approaches using the chi-square and Mann-Whitney U tests. RESULTS: After matching, 296 transperitoneal and 74 retroperitoneal cases were available for analysis, and matched groups were well balanced in terms of treatment year, age, gender, race, American Society of Anesthesiologists physical status classification (ASA) score, body mass index, tumor laterality, tumor size, R.E.N.A.L. (radius, exophytic/endophytic properties, nearness of tumor to the collecting system or sinus, anterior/posterior, location relative to polar lines) score, and hilar location. Compared with transperitoneal, the retroperitoneal approach was associated with significantly shorter mean LOS (2.2 vs 2.6 days, p = 0.01), but longer mean WIT (21 vs 19 minutes, p = 0.01). Intraoperative (p = 0.35) and postoperative complications (p = 0.65), operative time (p = 0.93), positive margins (p = 1.0), and latest eGFR preservation (p = 0.25) were not significantly different between approaches. No differences were detected in the other outcomes. CONCLUSIONS: Among high-volume surgeons, transperitoneal and retroperitoneal RPN achieved similar outcomes for posterior renal masses, although with slight differences in LOS and WIT. Retroperitoneal RPN may be an effective option for the treatment of certain small posterior renal masses

Characterization of designed, synthetically accessible bryostatin analog HIV latency reversing agents.

HIV latency in resting CD4+ T cell represents a key barrier preventing cure of the infection with antiretroviral drugs alone. Latency reversing agents (LRAs) can activate HIV expression in latently infected cells, potentially leading to their elimination through virus-mediated cytopathic effects, host immune responses, and/or therapeutic strategies targeting cells actively expressing virus. We have recently described several structurally simplified analogs of the PKC modulator LRA bryostatin (termed bryologs) designed to improve synthetic accessibility, tolerability in vivo, and efficacy in inducing HIV latency reversal. Here we report the comparative performance of lead bryologs, including their effects in reducing cell surface expression of HIV entry receptors, inducing proinflammatory cytokines, inhibiting short-term HIV replication, and synergizing with histone deacetylase inhibitors to reverse HIV latency. These data provide unique insights into structure-function relationships between A- and B-ring bryolog modifications and activities in primary cells, and suggest that bryologs represent promising leads for preclinical advancement

Understanding Paramagnetic Spin Correlations in the Spin-Liquid Pyrochlore Tb2Ti2O7

Recent elastic and inelastic neutron scattering studies of the highly frustrated pyrochlore antiferromagnet Tb2Ti2O7 have shown some very intriguing features that cannot be modeled by the local classical Ising model, naively expected to describe this system at low temperatures. Using the random phase approximation to take into account fluctuations between the ground state doublet and the first excited doublet, we successfully describe the elastic neutron scattering pattern and dispersion relations in Tb2Ti2O7, semi-quantitatively consistent with experimental observations.Comment: revtex4, 4 pages, 1 Color+ 2 BW figure

Light-Element Abundance Variations at Low Metallicity: the Globular Cluster NGC 5466

We present low-resolution (R~850) spectra for 67 asymptotic giant branch (AGB), horizontal branch and red giant branch (RGB) stars in the low-metallicity globular cluster NGC 5466, taken with the VIRUS-P integral-field spectrograph at the 2.7-m Harlan J. Smith telescope at McDonald Observatory. Sixty-six stars are confirmed, and one rejected, as cluster members based on radial velocity, which we measure to an accuracy of 16 km s-1 via template-matching techniques. CN and CH band strengths have been measured for 29 RGB and AGB stars in NGC 5466, and the band strength indices measured from VIRUS-P data show close agreement with those measured from Keck/LRIS spectra previously taken of five of our target stars. We also determine carbon abundances from comparisons with synthetic spectra. The RGB stars in our data set cover a range in absolute V magnitude from +2 to -3, which permits us to study the rate of carbon depletion on the giant branch as well as the point of its onset. The data show a clear decline in carbon abundance with rising luminosity above the luminosity function "bump" on the giant branch, and also a subdued range in CN band strength, suggesting ongoing internal mixing in individual stars but minor or no primordial star-to-star variation in light-element abundances.Comment: 10 pages, emulateapj format, AJ accepte

A Neutron Star Binary Merger Model for GW170817/GRB170817a/SSS17a

The merging neutron star gravitational wave event GW170817 has been observed throughout the entire electromagnetic spectrum from radio waves to $\gamma$-rays. The resulting energetics, variability, and light curves are shown to be consistent with GW170817 originating from the merger of two neutron stars, in all likelihood followed by the prompt gravitational collapse of the massive remnant. The available $\gamma$-ray, X-ray and radio data provide a clear probe for the nature of the relativistic ejecta and the non-thermal processes occurring within, while the ultraviolet, optical and infrared emission are shown to probe material torn during the merger and subsequently heated by the decay of freshly synthesized $r$-process material. The simplest hypothesis that the non-thermal emission is due to a low-luminosity short $\gamma$-ray burst (sGRB) seems to agree with the present data. While low luminosity sGRBs might be common, we show here that the collective prompt and multi-wavelength observations are also consistent with a typical, powerful sGRB seen off-axis. Detailed follow-up observations are thus essential before we can place stringent constraints on the nature of the relativistic ejecta in GW170817.Comment: 9 pages, 5 figures, accepted to ApJ Letter

Regurgitation Hemodynamics Alone Cause Mitral Valve Remodeling Characteristic of Clinical Disease States In Vitro

Mitral valve regurgitation is a challenging clinical condition that is frequent, highly varied, and poorly understood. While the causes of mitral regurgitation are multifactorial, how the hemodynamics of regurgitation impact valve tissue remodeling is an understudied phenomenon. We employed a pseudo-physiological flow loop capable of long-term organ culture to investigate the early progression of remodeling in living mitral valves placed in conditions resembling mitral valve prolapse (MVP) and functional mitral regurgitation (FMR). Valve geometry was altered to mimic the hemodynamics of controls (no changes from native geometry), MVP (5ﾠmm displacement of papillary muscles towards the annulus), and FMR (5ﾠmm apical, 5ﾠmm lateral papillary muscle displacement, 65% larger annular area). Flow measurements ensured moderate regurgitant fraction for regurgitation groups. After 1-week culture, valve tissues underwent mechanical and compositional analysis. MVP conditioned tissues were less stiff, weaker, and had elevated collagen III and glycosaminoglycans. FMR conditioned tissues were stiffer, more brittle, less extensible, and had more collagen synthesis, remodeling, and crosslinking related enzymes and proteoglycans, including decorin, matrix metalloproteinase-1, and lysyl oxidase. These models replicate clinical findings of MVP (myxomatous remodeling) and FMR (fibrotic remodeling), indicating that valve cells remodel extracellular matrix in response to altered mechanical homeostasis resulting from disease hemodynamics

Epithelial cell–derived secreted and transmembrane 1a signals to activated neutrophils during pneumococcal pneumonia

Airway epithelial cell responses are critical to the outcome of lung infection. In this study, we aimed to identify unique contributions of epithelial cells during lung infection. To differentiate genes induced selectively in epithelial cells during pneumonia, we compared genome-wide expression profiles from three sorted cell populations: epithelial cells from uninfected mouse lungs, epithelial cells from mouse lungs with pneumococcal pneumonia, and nonepithelial cells from those same infected lungs. Of 1,166 transcripts that were more abundant in epithelial cells from infected lungs compared with nonepithelial cells from the same lungs or from epithelial cells of uninfected lungs, 32 genes were identified as highly expressed secreted products. Especially strong signals included two related secreted and transmembrane (Sectm) 1 genes, Sectm1a and Sectm1b. Refinement of sorting strategies suggested that both Sectm1 products were induced predominantly in conducting airway epithelial cells. Sectm1 was induced during the early stages of pneumococcal pneumonia, and mutation of NF-kB RelA in epithelial cells did not diminish its expression. Instead, type I IFN signaling was necessary and sufficient for Sectm1 induction in lung epithelial cells, mediated by signal transducer and activator of transcription 1. For target cells, Sectm1a bound to myeloid cells preferentially, in particular Ly6GbrightCD11bbright neutrophils in the infected lung. In contrast, Sectm1a did not bind to neutrophils from uninfected lungs. Sectm1a increased expression of the neutrophil-attracting chemokine CXCL2 by neutrophils from the infected lung. We propose that Sectm1a is an epithelial product that sustains a positive feedback loop amplifying neutrophilic inflammation during pneumococcal pneumonia

Electromagnetic Evidence that SSS17a is the Result of a Binary Neutron Star Merger

11 hours after the detection of gravitational wave source GW170817 by the Laser Interferometer Gravitational-Wave Observatory and Virgo Interferometers, an associated optical transient SSS17a was discovered in the galaxy NGC 4993. While the gravitational wave data indicate GW170817 is consistent with the merger of two compact objects, the electromagnetic observations provide independent constraints of the nature of that system. Here we synthesize all optical and near-infrared photometry and spectroscopy of SSS17a collected by the One-Meter Two-Hemisphere collaboration. We find that SSS17a is unlike other known transients. The source is best described by theoretical models of a kilonova consisting of radioactive elements produced by rapid neutron capture (the r-process). We find that SSS17a was the result of a binary neutron star merger, reinforcing the gravitational wave result.Comment: 21 pages, 4 figures, accepted to Scienc

Genetically encoded reporters for hyperpolarized xenon magnetic resonance imaging

Magnetic resonance imaging (MRI) enables high-resolution non-invasive observation of the anatomy and function of intact organisms. However, previous MRI reporters of key biological processes tied to gene expression have been limited by the inherently low molecular sensitivity of conventional ^1H MRI. This limitation could be overcome through the use of hyperpolarized nuclei, such as in the noble gas xenon, but previous reporters acting on such nuclei have been synthetic. Here, we introduce the first genetically encoded reporters for hyperpolarized ^(129)Xe MRI. These expressible reporters are based on gas vesicles (GVs), gas-binding protein nanostructures expressed by certain buoyant microorganisms. We show that GVs are capable of chemical exchange saturation transfer interactions with xenon, which enables chemically amplified GV detection at picomolar concentrations (a 100- to 10,000-fold improvement over comparable constructs for ^1H MRI). We demonstrate the use of GVs as heterologously expressed indicators of gene expression and chemically targeted exogenous labels in MRI experiments performed on living cells