Block-Diagonalization and f-electron Effects in Tight-Binding Theory

We extend a tight-binding total energy method to include f-electrons, and apply it to the study of the structural and elastic properties of a range of elements from Be to U. We find that the tight-binding parameters are as accurate and transferable for f-electron systems as they are for d-electron systems. In both cases we have found it essential to take great care in constraining the fitting procedure by using a block-diagonalization procedure, which we describe in detail.Comment: 9 pages, 6 figure

The antenna sub-system for meteosat second generation satellites

The Meteosat Second Generation project (MSG) concerns a launch and operation of three new satellites in the coming years. MSG continues meteorological services, which are currently provided by the very successful first generation of satellites in the Meteosat Operational Program (MOP), operated by Eumetsat. MSG expands on the services offered by MOP by providing more frequently data in more observation bands, with higher resolution. The telecommunication system for the MSG satellite transmits the measured data to the primary ground station and receives and re-transmits pre-processed images and meteorological data from the latter station. It collects meteorological data from data collection platforms. The MSG satellite carries also a Search and Rescue transponder. The antenna sub-system has been specifically designed for the necessary functions and permits appropriate data throughput with the satellite spinning at a rate of 100 revolutions per minute. The antenna sub-system for MSG is explained, after a short general description

Structural Characterization and Modeling of Metallic Mesh Material for Large Deployable Reflectors

Metallic mesh is a key component of Large Deployable Reflectors for telecommunication and Earth observation spacecraft antennas. Deep knowledge of mesh structural characteristics and the possibility to numerically simulate its behaviour are mandatory steps for its correct use in the reflectors. The mesh is strongly compliant and anisotropic; hence, a specific testing machine has been designed and built, able to stretch the specimen along two directions, with uncoupled motion laws, controlled both in force and displacement. The mechanical characterization is driven so that a numerical simulation of the mesh is derived requiring only common finite element formulations

Structural Characterization and Modeling of Metallic Mesh Material for Large Deployable Reflectors

Metallic mesh is a key component of Large Deployable Reflectors for telecommunication and Earth observation spacecraft antennas. Deep knowledge of mesh structural characteristics and the possibility to numerically simulate its behaviour are mandatory steps for its correct use in the reflectors. The mesh is strongly compliant and anisotropic; hence, a specific testing machine has been designed and built, able to stretch the specimen along two directions, with uncoupled motion laws, controlled both in force and displacement. The mechanical characterization is driven so that a numerical simulation of the mesh is derived requiring only common finite element formulations

A Tunable, Biodegradable, Thin-Film Polymer Device as a Long-Acting Implant Delivering Tenofovir Alafenamide Fumarate for HIV Pre-exposure Prophylaxis

PURPOSE: The effectiveness of Tenofovir based HIV pre-exposure prophylaxis (PrEP) is proven, but hinges on correct and consistent use. User compliance and therapeutic effectiveness can be improved by long acting drug delivery systems. Here we describe a thin-film polymer device (TFPD) as a biodegradable subcutaneous implant for PrEP. METHODS: A thin-film polycaprolactone (PCL) membrane controls drug release from a reservoir. To achieve membrane controlled release, TAF requires a formulation excipient such as PEG300 to increase the dissolution rate and reservoir solubility. Short-term In vitro release studies are used to develop an empirical design model, which is applied to the production of in vitro prototype devices demonstrating up to 90-days of linear release and TAF chemical stability. RESULTS: The size and shape of the TFPD are tunable, achieving release rates ranging from 0.5–4.4 mg/day in devices no larger than a contraceptive implant. Based on published data for oral TAF, subcutaneous constant-rate release for HIV PrEP is estimated at < 2.8mg/day. Prototype devices demonstrated linear release at 1.2mg/day for up to 90 days and at 2.2mg/day for up to 60 days. CONCLUSIONS: We present a biodegradable TFPD for subcutaneous delivery of TAF for HIV PrEP. The size, shape and release rate of the device are tunable over a > 8-fold range

Automated selection of bone texture regions on hand radiographs: Data from the Osteoarthritis Initiative

Manual selection of finger trabecular bone texture regions on hand X-ray images is time-consuming, tedious, and observer-dependent. Therefore, we developed an automated method for the region selection. The method selects square trabecular bone regions of interest above and below the second to fifth distal and proximal interphalangeal joints. Two regions are selected per joint (16 regions per hand). The method consists of four integral parts: (1) segmentation of a radiograph into hand and background, (2) identification of finger regions, (3) localization of center points of heads of distal phalanges and the distal interphalangeal, proximal interphalangeal, and metacarpophalangeal joints, and (4) placement of the regions of interest under and above the distal and proximal interphalangeal joints. A gold standard was constructed from regions selected by two observers on 40 hand X-ray images taken from Osteoarthritis Initiative cohort. Datasets of 520 images were generated from the 40 images to study the effects of hand and finger positioning. The accuracy in regions selection and the agreement in calculating five directional fractal parameters were evaluated against the gold standard. The accuracy, agreement, and effects of hand and finger positioning were measured using similarity index (0 for no overlap and 1 for entire overlap) and interclass correlation coefficient as appropriate. A high accuracy in selecting regions (similarity index ≥ 0.79) and a good agreement in fractal parameters (interclass correlation coefficient ≥ 0.58) were achieved. Hand and finger positioning did not affect considerably the region selection (similarity index ≥ 0.70). These results indicate that the method developed selects bone regions on hand X-ray images with accuracy sufficient for fractal analyses of bone texture