Tech Briefs

HeartBeatID – Heart Electrical Actions as Biometric Indicia

Ames Research Center, Moffett Field, California One or more biometric indicia, such as fingerprints, voice prints, retinal scans, and facial features, are often used to identify or authenticate the identity of a user seeking access to a given resource. Cardiac muscle is myogenic and is capable of generating an action potential and depolarizing and repolarizing signals from within the muscle. An intrinsic conduction system (ICS), a group of specialized cardiac cells, passes an electrical signal throughout the heart as a PQRST (Preview, Question, Read, Study, Test) signature.

Posted in: Medical, Briefs

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Cryogenic Grinding for Mechanical Abrasion for Hardy Endospores

The method is far superior to conventional mechanical abrasion strategies. NASA’s Jet Propulsion Laboratory, Pasadena, California A comparative analysis was carried out between an emerging cryogenic grinding method and a conventional wet-chemistry/bead-beating endospore disruption approach. After extensive trial and error, it was determined that a regimen of three cryogenic grinding cycles of 2 minutes each was optimum for downstream DNA recovery. Spores embedded in ice exhibited a mere 1-log reduction in recovery following cryo-milling for up to 30 minutes. The observed total spore-borne DNA recovery was quite impressive, as well established, streamlined techniques for extracting DNA from endospores typically recover, at best, ≈10% of the molecules present. To facilitate the nucleic-acid-based testing required to detect and quantify DNA and endospores recovered, this innovation implements cryogenic grinding procedures followed by qPCR (quantitative polymerase chain reaction) methods to verify this novel capture technique.

Posted in: Medical, Briefs

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Making Mesh Buckypaper Capsules for Transplantation of Cells and Implantation of Medical Devices

Applications include gene therapy, cell transplantation for treatment of diabetes and other disorders, and improved biocompatibility of implantable medical devices. Ames Research Center, Moffett Field, California The innovation consists of a method for fabricating containers (“biocapsules”) made of biocompatible mesh for holding living cells and tissues, to facilitate transplantation into the body, for a wide range of high-impact medical applications. The biocompatible mesh (buckypaper) is made of carbon nanotubes (CNTs), and the containers are fabricated by depositing the nanotubes onto pre-formed molds, in order to achieve the desired shape and size of the biocapsule. Various forms are possible, including hollow tubes, closed cylinders, and more complex shapes, determined by the configuration of the mold. The biocompatibility of the capsule makes it possible to implant a variety of cells into a host, even cells that would otherwise be considered “foreign,” such as cells from unmatched donors, specially engineered cells, and even nonhuman cells. Because the capsule pores are too small for the cells to pass, the cells stay inside the capsule, where they are protected from the host immune system. The pores of the biocapsule permit gas exchange (oxygen, carbon dioxide), as well as free diffusion of metabolites, which keeps the cells healthy. Tissue or tissue fragments, and micro- or nano-scale medical devices can also be placed inside the biocapsule to facilitate their implantation into the body.

Posted in: Medical, Briefs

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Non-Binary Protograph-Based LDPC Codes for Short Block Lengths

The constrained protograph-based LDPC codes are a new class of codes proposed for low-complexity implementation of decoders. NASA’s Jet Propulsion Laboratory, Pasadena, California Short block codes are in demand by international space agencies for transmission of command and control data to spacecraft in the uplink channel. Codes that outperform currently used binary codes with the same block lengths and code rates are desirable. A design method constructs non-binary LDPC (low-density parity-check) codes both for unconstrained non-binary protograph-based codes and the new class of constrained protograph-based codes. The non-binary short block codes outperform the binary version by at least 1 dB for the same block size and code rate.

Posted in: Information Sciences, Electronics & Computers, Briefs

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Method Resolves Algebraic Loops While Improving Accuracy and Reducing Runtime

Higher accuracies are achieved while running at the lower base sample rate. Armstrong Flight Research Center, Edwards, California A method has been developed for resolving algebraic loops that occur in closed-loop systems when using MathWorks Simulink modeling and simulation tools. This variable fidelity method improves accuracy and reduces runtime significantly for users of Simulink Coder applications. The method improves the Simulink Coder tool’s ability to more efficiently and quickly generate C code based on algorithms modeled in the simulation tool. By replacing transfer functions that require high sampling rates with embedded function integration schemes, users can achieve continuous transfer function accuracy at almost no computational cost. The innovation also enables computationally intensive block diagrams to run faster in real time, and satisfies Nyquist frequency requirements in models. Algebraic loops are resolved through fast sampling, making the innovation especially applicable to high-speed systems with saturation limits, dead-bands, and other constraints that create fast dynamics.

Posted in: Information Sciences, Electronics & Computers, Briefs

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Solar Pumped Fiber Laser for Solar Sail Propulsion and Remote Power Transfer

The photovoltaic capability of any instrument can be enhanced by delivering extra power via a space-based, broadband laser beam. Goddard Space Flight Center, Greenbelt, Maryland A new method has been developed to create coherent laser light efficiently with direct optical coupling of the Sun’s energy into the gain medium for multiple uses. New advances in solar cell photovoltaic (PV) technologies have greatly improved their efficiencies, mostly by improving their ability to convert many wavelengths or wider bands of the solar spectrum to electricity. New advances in actively doped fibers and optical glasses have been shown to produce very broad, multi-line absorption bands as well as stimulated emission lines, or laser lines. By designing the optical cavity system to feed back all emission bands into the gain media for amplification, a multi-wavelength source can be generated requiring no electronics.

Posted in: Tech Briefs, Physical Sciences, Photonics, Briefs

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ELID Grinding of Large Aspheres

Goddard Space Flight Center, Greenbelt, Maryland This work focused on a manufacturing process to produce silicon carbide optical surfaces with low mid-spatial surface errors. Mid-spatial frequency (MSF) and high-spatial frequency (HSF) surface errors in the grinding of fast aspheres are amplified in hard ceramics like silicon carbide due to cyclic tool wear rates, vibration, and tool deformation.

Posted in: Tech Briefs, Photonics, Briefs

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