Non uniformity: structural strategy for optimizing functionality in skeletal ligaments

Ligaments serve as compliant connectors between hard tissues. In that role, they function under various load regimes and directions. However, the 3D structure of ligaments is still considered uniform. The periodontal ligament connects the tooth to the bone and like other ligaments, it sustains different types of loads in various directions. Using the PDL as a model, and employing a fabricated motorized set-up in a microCT instrument, morphological automated segmentation methods and 2nd harmonic generation imaging, we demonstrate that the fibrous network structure within the PDL is not uniform, even before the tooth becomes functional. We find that areas sustaining compression loads are pre-structured with sparse collagenous networks and large blood vessels, whereas other areas contain dense collagen networks with few blood vessels. Therefore, the PDL develops as a non-uniform structure, with an architecture designed to sustain specific types of load in different areas. Based on these findings, we propose that ligaments in general should be regarded as non-uniform entities structured for optimal functioning under variable load regimes.2019-09-26T00:00:00

Programmable rate modem utilizing digital signal processing techniques

The need for a Programmable Rate Digital Satellite Modem capable of supporting both burst and continuous transmission modes with either Binary Phase Shift Keying (BPSK) or Quadrature Phase Shift Keying (QPSK) modulation is discussed. The preferred implementation technique is an all digital one which utilizes as much digital signal processing (DSP) as possible. The design trade-offs in each portion of the modulator and demodulator subsystem are outlined

Tunable band gaps in bilayer graphene-BN heterostructures

We investigate band-gap tuning of bilayer graphene between hexagonal boron nitride sheets, by external electric fields. Using density functional theory, we show that the gap is continuously tunable from 0 to 0.2 eV, and is robust to stacking disorder. Moreover, boron nitride sheets do not alter the fundamental response from that of free-standing bilayer graphene, apart from additional screening. The calculations suggest that the graphene-boron nitride heterostructures could provide a viable route to graphene-based electronic devices.Comment: 12 pages, 5 figure

A Memristor as Multi-Bit Memory: Feasibility Analysis

The use of emerging memristor materials for advanced electrical devices such as multi-valued logic is expected to outperform today's binary logic digital technologies. We show here an example for such non-binary device with the design of a multi-bit memory. While conventional memory cells can store only 1 bit, memristors-based multi-bit cells can store more information within single device thus increasing the information storage density. Such devices can potentially utilize the non-linear resistance of memristor materials for efficient information storage. We analyze the performance of such memory devices based on their expected variations in order to determine the viability of memristor-based multi-bit memory. A design of read/write scheme and a simple model for this cell, lay grounds for full integration of memristor multi-bit memory cell