140 Mbit/s optical FSK fibre heterodyne experiment at 1.54 ?m

An optical fibre heterodyne experiment using 2-FSK modulation at 140 Mbit/s has been operated in the 1.5 ?m loss window. A receiver sensitivity of ?55 dBm has been obtained; operation over a fibre link of 199.7 km showed no additional system degradation.     

Detecting reduced bone mineral density from dental radiographs using statistical shape models.

We describe a novel method of estimating reduced bone mineral density (BMD) from dental panoramic tomograms (DPTs), which show the entire mandible. Careful expert width measurement of the inferior mandibular cortex has been shown to be predictive of BMD in hip and spine osteopenia and osteoporosis. We have implemented a method of automatic measurement of the width by active shape model search, using as training data 132 DPTs of female subjects whose BMD has been established by dual-energy X-ray absorptiometry. We demonstrate that widths measured after fully automatic search are significantly correlated with BMD, and exhibit less variability than manual measurements made by different experts. The correlation is highest towards the lateral region of the mandible, in a position different from that previously employed for manual width measurement. An receiver-operator characterstic (ROC) analysis for identifying osteopenia (T < -1: BMD more than one standard deviation below that of young healthy females) gives an area under curve (AUC) value of 0.64. Using a minimal interaction to initiate active shape model (ASM) search, the measurement can be made at the optimum region of the mandible, resulting in an AUC value of 0.71. Using an independent test set, AUC for detection of osteoporosis (T < -2.5) is 0.81.     

Biopolymer Networks for the Solid‐State Production of Porous Magnetic Beads and Wires

Aqueous solutions of sodium carboxymethyl cellulose are used for the morphosynthesis of spherical and wire‐shaped biopolymer networks, in which Fe³⁺ cations serve as a crosslinking and hardening agent. Their morphology remains intact upon drying, resulting in monolithic beads (1 mm) and wires (ca. 80 μm), which are exploited as reaction vessels to pre‐encapsulate poly(ethylene glycol) 400 (PEG 400) and cobalt cations. A solid‐state reaction in an inert atmosphere at 600 °C affords porous carbonaceous xerogels, macroscopically shaped as beads or wires and decorated with nanocrystalline magnetic iron oxide, metallic iron, or iron–cobalt alloy particles, thus imparting magnetic properties to the products. As such the reduction of Fe³⁺ species to α‐Fe nanoparticles can be achieved without H₂ treatment, since poly(ethylene glycol) serves as a reducing agent and the encapsulated Co²⁺ aids in the subsequent growth of the metallic iron particles. Particularly interesting are the magnetic properties of the carbon–α‐Fe composite, in which the size of the magnetic particles, estimated near the boundaries of the single magnetic domain, gives rise to increased coercivity compared with that of bulk iron.     

Dual-Polarization-Sensitive Kinetic Inductance Detectors for Balloon-borne Sub-millimeter Polarimetry

We are developing arrays of kinetic inductance detectors for sub-millimeter polarimetry that will be deployed on the BLAST balloon-borne instrument. The array is feedhorn-coupled, and each pixel contains two lumped-element kinetic inductance detectors (LEKIDs) made of TiN. The absorbing, inductive sections of the LEKID-pair are orthogonal, which allows simultaneous measurement of both horizontal and vertical polarizations within one spatial pixel. In this paper, we show efficient absorption in TiN films when coupled to waveguide at room temperature and present dark measurements of single polarization devices with varying capacitor geometries. We show that it will be difficult to achieve background-limited performance in BLAST with stoichiometric TiN films with T \(_{c}=4.5\)  K, and that non-stoichiometric films with lower T \(_{c}\) will be required.     

MUSTANG 2: A Large Focal Plane Array for the 100 m Green Bank Telescope

This paper describes MUSTANG 2, a 338 element focal plane array that is being built for the Green Bank Telescope. Each element consists of a profiled feedhorn coupled to two transition edge sensor bolometers, one for each polarization. Initial deployment will be with 32 detectors, but once fully populated, MUSTANG 2 will be capable of mapping a \(8'\times 8'\) area to \(23~\upmu \) Jy in 1 h with good image fidelity on angular scales from \(9''\) to \(6'\) . As well as an instrument overview, the choice of bandpass and the design of the feeds, detectors and readout are given.     

Improving Infection Resistance in Tissue Engineered Scaffolds for Tensile Applications Using Vancomycin-Embedded Melt Electrowritten Scaffolds

It is important to consider mechanical, biological, and antibacterial properties of scaffolds when used for tissue engineering applications. This study presents a method to create complex “wavy” architecture polycaprolactone (PCL) scaffolds toward the development of tissue engineered ligament and tendon tissue substitutes, fabricated using melt electrowriting (MEW) and loaded with vancomycin (5, 10, and 25% w/w). Scaffolds are characterized for both mechanical and biological properties. Loading PCL scaffolds with vancomycin with modified solvent evaporation technique achieves a high loading efficiency of maximum 18% w/w and high encapsulation efficiency with over 89%. Vancomycin loaded PCL scaffolds with all three doses (5, 10, and 25% w/w) display antibacterial activity against Gram-positive Staphylococcus aureus (S. aureus) up to 14 days of release. Initial burst followed by a sustained release is observed on all three vancomycin loaded scaffolds for up to 28 days. Importantly, in addition to antibacterial properties, vancomycin-loaded PCL scaffolds also display improved mechanical properties compared to traditional crosshatch design MEW scaffolds and are noncytotoxic at all concentrations as demonstrated by live-dead staining, cell attachment and proliferation assays indicating its potential as an effective treatment option for tissue regeneration in rotator cuff injuries or other tissues undergoing tensile biomechanical loading.     

The separation of two different sized particles in an evaporating droplet

The separation of two different sized particles during evaporation of a dilute droplet is examined both computationally and experimentally. A transport model of the evaporating droplet system was solved using the finite element method to determine the fluid velocity, pressure, vapor concentration surrounding the droplet, temperature, and both particle concentrations. Experimentally, 1 μm and 3 μm polystyrene particles were used during the evaporation of a sessile water droplet. It was determined that to accurately model particle deposition, thermal effects need to be considered. The Marangoni currents in evaporating droplets keep particles suspended in the droplet until the end of the evaporation. Previous models of particle deposition during droplet evaporation have rapid accumulation of particles at the contact line. Our experiments and the experiments of others demonstrate that this is not accurate physically. In addition, to model the separation of two different sized particles the consideration of thermal effects is essential. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3547–3556, 2015     

Design Rules for Addressing Material Asymmetry Induced by Templated Epitaxy for Integrated Heteroepitaxial On-Chip Light Sources

Integrating quantum dot (QD) gain elements onto Si photonic platforms via direct epitaxial growth is the ultimate solution for realizing on-chip light sources. Tremendous improvements in device performance and reliability have been demonstrated in devices grown on planar Si substrates in the last few years. Recently, electrically pumped QD lasers deposited in narrow oxide pockets in a butt-coupled configuration and on-chip coupling have been realized on patterned Si photonic wafers. However, the device yield and reliability, which ultimately determines the scalability of such technology, are limited by material uniformity. Here, detailed analysis is performed, both experimentally and theoretically, on the material asymmetry induced by the pocket geometry and provides unambiguous evidence suggesting that all pockets should be aligned to the [1 $\overline{1}0$] direction of the III-V crystal for high yield, high performance, and scalable on-chip light sources at 300 mm scale.