Improved hemocompatibility of silicone rubber extracorporeal tubing via solvent swelling-impregnation of S-nitroso-N-acetylpenicillamine (SNAP) and evaluation in rabbit thrombogenicity model.

PubMed

Brisbois, Elizabeth J; Major, Terry C; Goudie, Marcus J; Bartlett, Robert H; Meyerhoff, Mark E; Handa, Hitesh

2016-06-01

Blood-contacting devices, including extracorporeal circulation (ECC) circuits, can suffer from complications due to platelet activation and thrombus formation. Development of nitric oxide (NO) releasing polymers is one method to improve hemocompatibility, taking advantage of the ability of low levels of NO to prevent platelet activation/adhesion. In this study a novel solvent swelling method is used to load the walls of silicone rubber tubing with the NO donor S-nitroso-N-acetylpenicillamine (SNAP). This SNAP-silicone rubber tubing exhibits an NO flux of ca. 1×10(-10)molcm(-2)min(-1), which mimics the range of NO release from the normal endothelium, which is stable for at least 4h. Images of the tubing before and after swelling, obtained via scanning electron microscopy, demonstrate that this swelling method has little effect on the surface properties of the tubing. The SNAP-loaded silicone rubber and silicone rubber control tubing are used to fabricate ECC circuits that are evaluated in a rabbit model of thrombogenicity. After 4h of blood flow, the SNAP-loaded silicone rubber circuits were able to preserve the blood platelet count at 64% of baseline (vs. 12% for silicone rubber control). A 67% reduction in the degree of thrombus formation within the thrombogenicity chamber was also observed. This study demonstrates the ability to improve the hemocompatibility of existing/commercial silicone rubber tubing via a simple solvent swelling-impregnation technique, which may also be applicable to other silicone-based blood-contacting devices. Localized nitric oxide (NO) release can be achieved from biomedical grade polymers doped with S-nitroso-N-acetylpenicillamine (SNAP). Despite the promising in vitro and in vivo biocompatibility results reported for these NO releasing polymers, many of these materials may face challenges in being translated to clinical applications, especially in the areas of polymer processing and manufacturing. In this study, we report a solvent swelling-impregnation technique to incorporate SNAP into extracorporeal circuit (ECC) tubing. These NO-releasing ECCs were able to attenuate the activation of platelets and maintain their functionality, while significantly reducing the extent of thrombus formation during 4h blood flow in the rabbit model of thrombogenicity. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Memristor emulator causes dissimilarity on a coupled memristive systems

NASA Astrophysics Data System (ADS)

Sabarathinam, S.; Prasad, Awadhesh

2018-04-01

The memristor is known as abasic fourth passive solid state circuit element. Itgaining increasing attention to create the next generation electronic devices commonly used as fundamental chaotic circuit although often arbitrary (typically piecewise linear or cubic) fluxcharge characteristics. In thispresent work, the causes of the memristor emulator studied in a coupled memristive chaoticoscillator for the first time. We confirm that the emulator that allows synchronization between theoscillators and cause the dissimilarity between the systems when increasing the couplingstrength, and co-efficient of the memristor emulator. The detailed statistical analysis was performed to confirm such phenomenon.

Nitric oxide therapies for local inhibition of platelets' activitation on blood-contacting surfaces

NASA Astrophysics Data System (ADS)

Amoako, Kagya Agyeman

Blood-contacting devices interact with blood during their function much like the endothelium that modulates hemostasis. The surfaces of these devices however, lack endothelial-like properties, and consequently, upon blood contact, activate clotting factors to form clots. Systemic heparinization for inhibiting clot formation can cause bleeding and surface coatings show insignificant benefits. This research investigated nitric oxide (NO) production mimicry of the endothehum on artificial lungs (ALs) and pediatric catheters. Their surfaces were functionalized either by (1) entrapping NO donors inside their bulk, (2) incorporating catalysts to generate NO from NO-donors or (3) supplementing NO into sweep gas of artificial lungs. Pediatric catheters functionalized with NO-donor thin coats using method 1 is limited by short NO release duration. Method 2 has not been applied to large surface-area, low-flow devices like the AL. In this work NO-generating silicone membranes were synthesized and characterized to determine the relationship between surface properties, NO flux, and blood clotting time. These outcomes helped develop and optimize NO-generating gas-exchange silicone fibers that represent the majority of ALs surface area. The first NO-generating AL prototypes, using those fibers, were manufactured, incorporated into NO-generating circuits and tested for their non-thrombogenicity. To test for NO-release duration and non-thrombogenicity, catheters were fabricated to incorporate NO-donors inside their walls, characterized for NO flux and release duration by chemilumincscence, and tested for patency using a thrombogenicity model in rabbits. Methods 1-2 involve material modification using complicated and expensive chemical formulations and/or manufacturing. Method 3 however, functionalizes ALs by only adding NO into sweep gas. Decade-long anti-clotting testing using a wide range of NO concentrations has been conducted without knowledge of what concentration yields endothelial NO flux levels in the AL. This concentration was determined for the MC3 Biolung and the Terumo capiox rx25 ALs in vitro. All these ideas have shown positive results in short-term studies, and each may play a necessary role in inhibiting clot formation in future ALs. The sufficiency however, of each idea or of a combination for clot inhibition in long-term ALs remains to be determined.

Method using in vivo quantitative spectroscopy to guide design and optimization of low-cost, compact clinical imaging devices: emulation and evaluation of multispectral imaging systems

NASA Astrophysics Data System (ADS)

Saager, Rolf B.; Baldado, Melissa L.; Rowland, Rebecca A.; Kelly, Kristen M.; Durkin, Anthony J.

2018-04-01

With recent proliferation in compact and/or low-cost clinical multispectral imaging approaches and commercially available components, questions remain whether they adequately capture the requisite spectral content of their applications. We present a method to emulate the spectral range and resolution of a variety of multispectral imagers, based on in-vivo data acquired from spatial frequency domain spectroscopy (SFDS). This approach simulates spectral responses over 400 to 1100 nm. Comparing emulated data with full SFDS spectra of in-vivo tissue affords the opportunity to evaluate whether the sparse spectral content of these imagers can (1) account for all sources of optical contrast present (completeness) and (2) robustly separate and quantify sources of optical contrast (crosstalk). We validate the approach over a range of tissue-simulating phantoms, comparing the SFDS-based emulated spectra against measurements from an independently characterized multispectral imager. Emulated results match the imager across all phantoms (<3 % absorption, <1 % reduced scattering). In-vivo test cases (burn wounds and photoaging) illustrate how SFDS can be used to evaluate different multispectral imagers. This approach provides an in-vivo measurement method to evaluate the performance of multispectral imagers specific to their targeted clinical applications and can assist in the design and optimization of new spectral imaging devices.

Simulation, measurement, and emulation of photovoltaic modules using high frequency and high power density power electronic circuits

NASA Astrophysics Data System (ADS)

Erkaya, Yunus

The number of solar photovoltaic (PV) installations is growing exponentially, and to improve the energy yield and the efficiency of PV systems, it is necessary to have correct methods for simulation, measurement, and emulation. PV systems can be simulated using PV models for different configurations and technologies of PV modules. Additionally, different environmental conditions of solar irradiance, temperature, and partial shading can be incorporated in the model to accurately simulate PV systems for any given condition. The electrical measurement of PV systems both prior to and after making electrical connections is important for attaining high efficiency and reliability. Measuring PV modules using a current-voltage (I-V) curve tracer allows the installer to know whether the PV modules are 100% operational. The installed modules can be properly matched to maximize performance. Once installed, the whole system needs to be characterized similarly to detect mismatches, partial shading, or installation damage before energizing the system. This will prevent any reliability issues from the onset and ensure the system efficiency will remain high. A capacitive load is implemented in making I-V curve measurements with the goal of minimizing the curve tracer volume and cost. Additionally, the increase of measurement resolution and accuracy is possible via the use of accurate voltage and current measurement methods and accurate PV models to translate the curves to standard testing conditions. A move from mechanical relays to solid-state MOSFETs improved system reliability while significantly reducing device volume and costs. Finally, emulating PV modules is necessary for testing electrical components of a PV system. PV emulation simplifies and standardizes the tests allowing for different irradiance, temperature and partial shading levels to be easily tested. Proper emulation of PV modules requires an accurate and mathematically simple PV model that incorporates all known system variables so that any PV module can be emulated as the design requires. A non-synchronous buck converter is proposed for the emulation of a single, high-power PV module using traditional silicon devices. With the proof-of-concept working and improvements in efficiency, power density and steady-state errors made, dynamic tests were performed using an inverter connected to the PV emulator. In order to improve the dynamic characteristics, a synchronous buck converter topology is proposed along with the use of advanced GaNFET devices which resulted in very high power efficiency and improved dynamic response characteristics when emulating PV modules.

A device for emulating cuff recordings of action potentials propagating along peripheral nerves.

PubMed

Rieger, Robert; Schuettler, Martin; Chuang, Sheng-Chih

2014-09-01

This paper describes a device that emulates propagation of action potentials along a peripheral nerve, suitable for reproducible testing of bio-potential recording systems using nerve cuff electrodes. The system is a microcontroller-based stand-alone instrument which uses established nerve and electrode models to represent neural activity of real nerves recorded with a nerve cuff interface, taking into consideration electrode impedance, voltages picked up by the electrodes, and action potential propagation characteristics. The system emulates different scenarios including compound action potentials with selectable propagation velocities and naturally occurring nerve traffic from different velocity fiber populations. Measured results from a prototype implementation are reported and compared with in vitro recordings from Xenopus Laevis frog sciatic nerve, demonstrating that the electrophysiological setting is represented to a satisfactory degree, useful for the development, optimization and characterization of future recording systems.

Development of Wave Turbine Emulator in a Laboratory Environment

NASA Astrophysics Data System (ADS)

Vinatha, U.; Vittal K, P.

2013-07-01

Wave turbine emulator (WTE) is an important equipment for developing wave energy conversion system. The emulator reflects the actual behavior of the wave turbine by reproducing the characteristics of real wave turbine without reliance on natural wave resources and actual wave turbine. It offers a controllable test environment that allows the evaluation and improvement of control schemes for electric generators. The emulator can be used for research applications to drive an electrical generator in a similar way as a practical wave turbine. This article presents the development of a WTE in a laboratory environment and studies on the behavior of electrical generator coupled to the emulator. The structure of a WTE consists of a PC where the characteristics of the turbine are implemented, ac drive to emulate the turbine rotor, feedback mechanism from the drive and power electronic equipment to control the drive. The feedback signal is acquired by the PC through an A/D converter, and the signal for driving the power electronic device comes from the PC through a D/A converter.

Human plasma-derived immunoglobulin G fractionated by an aqueous two-phase system, caprylic acid precipitation, and membrane chromatography has a high purity level and is free of detectable in vitro thrombogenic activity.

PubMed

Vargas, M; Segura, Á; Wu, Y-W; Herrera, M; Chou, M-L; Villalta, M; León, G; Burnouf, T

2015-02-01

Instituto Clodomiro Picado has developed an immunoglobulin G (IgG) plasma fractionation process combining a polyethylene glycol/phosphate aqueous two-phase system (ATPS), caprylic acid precipitation and anion-exchange membrane chromatography. We evaluated the purity and in vitro thrombogenicity of such IgG, in line with current international requirements. Contributions of the different production steps to reduce thrombogenicity were assessed at 0·2 l-scale, and then the methodology was scaled-up to a 10 l-scale and final products (n = 3) were analysed. Purity, immunoglobulin composition, and subclass distribution were determined by electrophoretic and immunochemical methods. The in vitro thrombogenic potential was determined by a thrombin generation assay (TGA) using a Technothrombin fluorogenic substrate. Prekallikrein activator (PKA), plasmin, factor Xa, thrombin and thrombin-like activities were assessed using S-2302, S-2251, S-2222, S-2238 and S-2288 chromogenic substrates, respectively, and FXI by an ELISA. The thrombogenicity markers were reduced mostly during the ATPS step and were found to segregate mostly into the discarded liquid upper phase. The caprylic acid precipitation eliminated the residual procoagulant activity. The IgG preparations made from the 10 l-batches contained 100% gamma proteins, low residual IgA and undetectable IgM. The IgG subclass distribution was not substantially affected by the process. TGA and amidolytic activities revealed an undetectable in vitro thrombogenic risk and the absence of proteolytic enzymes in the final product. Fractionating human plasma by an ATPS combined with caprylic acid and membrane chromatography resulted in an IgG preparation of high purity and free of a detectable in vitro thrombogenic risk. © 2014 International Society of Blood Transfusion.

Performance tests of a power-electronics converter for multi-megawatt wind turbines using a grid emulator

NASA Astrophysics Data System (ADS)

Rizqy Averous, Nurhan; Berthold, Anica; Schneider, Alexander; Schwimmbeck, Franz; Monti, Antonello; De Doncker, Rik W.

2016-09-01

A vast increase of wind turbines (WT) contribution in the modern electrical grids have led to the development of grid connection requirements. In contrast to the conventional test method, testing power-electronics converters for WT using a grid emulator at Center for Wind Power Drives (CWD) RWTH Aachen University offers more flexibility for conducting test scenarios. Further analysis on the performance of the device under test (DUT) is however required when testing with grid emulator since the characteristic of the grid emulator might influence the performance of the DUT. This paper focuses on the performance analysis of the DUT when tested using grid emulator. Beside the issue regarding the current harmonics, the performance during Fault Ride-Through (FRT) is discussed in detail. A power hardware in the loop setup is an attractive solution to conduct a comprehensive study on the interaction between the power-electronics converters and the electrical grids.

Characterization and Compensation of Network-Level Anomalies in Mixed-Signal Neuromorphic Modeling Platforms

PubMed Central

Petrovici, Mihai A.; Vogginger, Bernhard; Müller, Paul; Breitwieser, Oliver; Lundqvist, Mikael; Muller, Lyle; Ehrlich, Matthias; Destexhe, Alain; Lansner, Anders; Schüffny, René; Schemmel, Johannes; Meier, Karlheinz

2014-01-01

Advancing the size and complexity of neural network models leads to an ever increasing demand for computational resources for their simulation. Neuromorphic devices offer a number of advantages over conventional computing architectures, such as high emulation speed or low power consumption, but this usually comes at the price of reduced configurability and precision. In this article, we investigate the consequences of several such factors that are common to neuromorphic devices, more specifically limited hardware resources, limited parameter configurability and parameter variations due to fixed-pattern noise and trial-to-trial variability. Our final aim is to provide an array of methods for coping with such inevitable distortion mechanisms. As a platform for testing our proposed strategies, we use an executable system specification (ESS) of the BrainScaleS neuromorphic system, which has been designed as a universal emulation back-end for neuroscientific modeling. We address the most essential limitations of this device in detail and study their effects on three prototypical benchmark network models within a well-defined, systematic workflow. For each network model, we start by defining quantifiable functionality measures by which we then assess the effects of typical hardware-specific distortion mechanisms, both in idealized software simulations and on the ESS. For those effects that cause unacceptable deviations from the original network dynamics, we suggest generic compensation mechanisms and demonstrate their effectiveness. Both the suggested workflow and the investigated compensation mechanisms are largely back-end independent and do not require additional hardware configurability beyond the one required to emulate the benchmark networks in the first place. We hereby provide a generic methodological environment for configurable neuromorphic devices that are targeted at emulating large-scale, functional neural networks. PMID:25303102

Characterization and compensation of network-level anomalies in mixed-signal neuromorphic modeling platforms.

PubMed

Petrovici, Mihai A; Vogginger, Bernhard; Müller, Paul; Breitwieser, Oliver; Lundqvist, Mikael; Muller, Lyle; Ehrlich, Matthias; Destexhe, Alain; Lansner, Anders; Schüffny, René; Schemmel, Johannes; Meier, Karlheinz

2014-01-01

Advancing the size and complexity of neural network models leads to an ever increasing demand for computational resources for their simulation. Neuromorphic devices offer a number of advantages over conventional computing architectures, such as high emulation speed or low power consumption, but this usually comes at the price of reduced configurability and precision. In this article, we investigate the consequences of several such factors that are common to neuromorphic devices, more specifically limited hardware resources, limited parameter configurability and parameter variations due to fixed-pattern noise and trial-to-trial variability. Our final aim is to provide an array of methods for coping with such inevitable distortion mechanisms. As a platform for testing our proposed strategies, we use an executable system specification (ESS) of the BrainScaleS neuromorphic system, which has been designed as a universal emulation back-end for neuroscientific modeling. We address the most essential limitations of this device in detail and study their effects on three prototypical benchmark network models within a well-defined, systematic workflow. For each network model, we start by defining quantifiable functionality measures by which we then assess the effects of typical hardware-specific distortion mechanisms, both in idealized software simulations and on the ESS. For those effects that cause unacceptable deviations from the original network dynamics, we suggest generic compensation mechanisms and demonstrate their effectiveness. Both the suggested workflow and the investigated compensation mechanisms are largely back-end independent and do not require additional hardware configurability beyond the one required to emulate the benchmark networks in the first place. We hereby provide a generic methodological environment for configurable neuromorphic devices that are targeted at emulating large-scale, functional neural networks.

Evaluation of thrombogenicity of beta-propiolactone/ultraviolet (beta-PL/UV) treated PPSB in chimpanzees

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kotitschke, R.; Stephan, W.; Prince, A.M.

1983-05-01

The thrombogenicity of beta-PL/UV-treated PPSB (factor IX concentrate) was evaluated in chimpanzees. PPSB isolated from beta-propiolactone-treated and UV-irradiated plasma was injected into chimpanzees at a dose of approximately 100 units/kg body weight. An FDA licensed PPSB preparation served as the negative control, and a preparation containing activated as well as precursor clotting factors served as the positive control. 15 minutes, 1 h, 4 h, and 24 h after the PPSB application the following parameters were determined in the chimpanzee blood: factors II, VII, IX, X, VIII, fibrinogen, AT III, thrombin coagulase, Quick value, APTT and platelet count. Neither the untreatedmore » control preparation, nor the PPSB isolated from beta-propiolactone-treated and UV-irradiated plasma, showed signs of thrombogenicity in the chimpanzee model. The positive control indicated that the chimpanzee is a suitable model for the thrombogenicity testing of activated clotting factors.« less

Organic core-sheath nanowire artificial synapses with femtojoule energy consumption.

PubMed

Xu, Wentao; Min, Sung-Yong; Hwang, Hyunsang; Lee, Tae-Woo

2016-06-01

Emulation of biological synapses is an important step toward construction of large-scale brain-inspired electronics. Despite remarkable progress in emulating synaptic functions, current synaptic devices still consume energy that is orders of magnitude greater than do biological synapses (~10 fJ per synaptic event). Reduction of energy consumption of artificial synapses remains a difficult challenge. We report organic nanowire (ONW) synaptic transistors (STs) that emulate the important working principles of a biological synapse. The ONWs emulate the morphology of nerve fibers. With a core-sheath-structured ONW active channel and a well-confined 300-nm channel length obtained using ONW lithography, ~1.23 fJ per synaptic event for individual ONW was attained, which rivals that of biological synapses. The ONW STs provide a significant step toward realizing low-energy-consuming artificial intelligent electronics and open new approaches to assembling soft neuromorphic systems with nanometer feature size.

Subspace projection method for unstructured searches with noisy quantum oracles using a signal-based quantum emulation device

NASA Astrophysics Data System (ADS)

La Cour, Brian R.; Ostrove, Corey I.

2017-01-01

This paper describes a novel approach to solving unstructured search problems using a classical, signal-based emulation of a quantum computer. The classical nature of the representation allows one to perform subspace projections in addition to the usual unitary gate operations. Although bandwidth requirements will limit the scale of problems that can be solved by this method, it can nevertheless provide a significant computational advantage for problems of limited size. In particular, we find that, for the same number of noisy oracle calls, the proposed subspace projection method provides a higher probability of success for finding a solution than does an single application of Grover's algorithm on the same device.

MemFlash device: floating gate transistors as memristive devices for neuromorphic computing

NASA Astrophysics Data System (ADS)

Riggert, C.; Ziegler, M.; Schroeder, D.; Krautschneider, W. H.; Kohlstedt, H.

2014-10-01

Memristive devices are promising candidates for future non-volatile memory applications and mixed-signal circuits. In the field of neuromorphic engineering these devices are especially interesting to emulate neuronal functionality. Therefore, new materials and material combinations are currently investigated, which are often not compatible with Si-technology processes. The underlying mechanisms of the device often remain unclear and are paired with low device endurance and yield. These facts define the current most challenging development tasks towards a reliable memristive device technology. In this respect, the MemFlash concept is of particular interest. A MemFlash device results from a diode configuration wiring scheme of a floating gate transistor, which enables the persistent device resistance to be varied according to the history of the charge flow through the device. In this study, we investigate the scaling conditions of the floating gate oxide thickness with respect to possible applications in the field of neuromorphic engineering. We show that MemFlash cells exhibit essential features with respect to neuromorphic applications. In particular, cells with thin floating gate oxides show a limited synaptic weight growth together with low energy dissipation. MemFlash cells present an attractive alternative for state-of-art memresitive devices. The emulation of associative learning is discussed by implementing a single MemFlash cell in an analogue circuit.

Cinematic camera emulation using two-dimensional color transforms

NASA Astrophysics Data System (ADS)

McElvain, Jon S.; Gish, Walter

2015-02-01

For cinematic and episodic productions, on-set look management is an important component of the creative process, and involves iterative adjustments of the set, actors, lighting and camera configuration. Instead of using the professional motion capture device to establish a particular look, the use of a smaller form factor DSLR is considered for this purpose due to its increased agility. Because the spectral response characteristics will be different between the two camera systems, a camera emulation transform is needed to approximate the behavior of the destination camera. Recently, twodimensional transforms have been shown to provide high-accuracy conversion of raw camera signals to a defined colorimetric state. In this study, the same formalism is used for camera emulation, whereby a Canon 5D Mark III DSLR is used to approximate the behavior a Red Epic cinematic camera. The spectral response characteristics for both cameras were measured and used to build 2D as well as 3x3 matrix emulation transforms. When tested on multispectral image databases, the 2D emulation transforms outperform their matrix counterparts, particularly for images containing highly chromatic content.

The influence of biomaterials on endothelial cell thrombogenicity

PubMed Central

McGuigan, Alison P.; Sefton, Michael V.

2007-01-01

Driven by tissue engineering and regenerative medicine, endothelial cells are being used in combination with biomaterials in a number of applications for the purpose of improving blood compatibility and host integration. Endothelialized vascular grafts are beginning to be used clinically with some success in some centers, while endothelial seeding is being explored as a means of creating a vasculature within engineered tissues. The underlying assumption of this strategy is that when cultured on artificial biomaterials, a confluent layer of endothelial cells maintain their non-thrombogenic phenotype. In this review the existing knowledge base of endothelial cell thrombogenicity cultured on a number of different biomaterials is summarized. The importance of selecting appropriate endpoint measures that are most reflective of overall surface thrombogenicity is the focus of this review. Endothelial cells inhibit thrombosis through three interconnected regulatory systems (1) the coagulation cascade (2) the cellular components of the blood such as leukocytes and platelets and (3) the complement cascade, and also through effects on fibrinolysis and vascular tone, the latter which influences blood flow. Thus, in order to demonstrate the thromobgenic benefit of seeding a biomaterial with EC, the conditions under which EC surfaces are more likely to exhibit lower thrombogenicity than unseeded biomaterial surfaces need to be consistent with the experimental context. The endpoints selected should be appropriate for the dominant thrombotic process that occurs under the given experimental conditions. PMID:17316788

Micro-RNA-126 Reduces the Blood Thrombogenicity in Diabetes Mellitus via Targeting of Tissue Factor.

PubMed

Witkowski, Marco; Weithauser, Alice; Tabaraie, Termeh; Steffens, Daniel; Kränkel, Nicolle; Witkowski, Mario; Stratmann, Bernd; Tschoepe, Diethelm; Landmesser, Ulf; Rauch-Kroehnert, Ursula

2016-06-01

Diabetes mellitus involves vascular inflammatory processes and is a main contributor to cardiovascular mortality. Notably, heightened levels of circulating tissue factor (TF) account for the increased thrombogenicity and put those patients at risk for thromboembolic events. Here, we sought to investigate the role of micro-RNA (miR)-driven TF expression and thrombogenicity in diabetes mellitus. Plasma samples of patients with diabetes mellitus were analyzed for TF protein and activity as well as miR-126 expression before and after optimization of the antidiabetic treatment. We found low miR-126 levels to be associated with markedly increased TF protein and TF-mediated thrombogenicity. Reduced miR-126 expression was accompanied by increased vascular inflammation as evident from the levels of vascular adhesion molecule-1 and fibrinogen, as well as leukocyte counts. With optimization of the antidiabetic treatment miR-126 levels increased and thrombogenicity was reduced. Using a luciferase reporter system, we demonstrated miR-126 to directly bind to the F3-3'-untranslated region, thereby reducing TF expression both on mRNA and on protein levels in human microvascular endothelial cells as well as TF mRNA and activity in monocytes. Circulating miR-126 exhibits antithrombotic properties via regulating post-transcriptional TF expression, thereby impacting the hemostatic balance of the vasculature in diabetes mellitus. © 2016 The Authors.

Surface modification of a biodegradable magnesium alloy with phosphorylcholine (PC) and sulfobetaine (SB) functional macromolecules for reduced thrombogenicity and acute corrosion resistance.

PubMed

Ye, Sang-Ho; Jang, Yong-Seok; Yun, Yeo-Heung; Shankarraman, Venkat; Woolley, Joshua R; Hong, Yi; Gamble, Lara J; Ishihara, Kazuhiko; Wagner, William R

2013-07-02

Siloxane functionalized phosphorylcholine (PC) or sulfobetaine (SB) macromolecules (PCSSi or SBSSi) were synthesized to act as surface modifying agents for degradable metallic surfaces to improve acute blood compatibility and slow initial corrosion rates. The macromolecules were synthesized using a thiol-ene radical photopolymerization technique and then utilized to modify magnesium (Mg) alloy (AZ31) surfaces via an anhydrous phase deposition of the silane functional groups. X-ray photoelectron spectroscopy surface analysis results indicated successful surface modification based on increased nitrogen and phosphorus or sulfur composition on the modified surfaces relative to unmodified AZ31. In vitro acute thrombogenicity assessment after ovine blood contact with the PCSSi and SBSSi modified surfaces showed a significant decrease in platelet deposition and bulk phase platelet activation compared with the control alloy surfaces. Potentiodynamic polarization and electrochemical impedance spectroscopy data obtained from electrochemical corrosion testing demonstrated increased corrosion resistance for PCSSi- and SBSSi-modified AZ31 versus unmodified surfaces. The developed coating technique using PCSSi or SBSSi showed promise in acutely reducing both the corrosion and thrombotic processes, which would be attractive for application to blood contacting devices, such as vascular stents, made from degradable Mg alloys.

Bioelectronic Sensors and Devices

NASA Astrophysics Data System (ADS)

Reed, Mark

Nanoscale electronic devices have recently enabled the ability to controllably probe biological systems, from the molecular to the cellular level, opening up new applications and understanding of biological function and response. This talk reviews some of the advances in the field, ranging from diagnostic and therapeutic applications, to cellular manipulation and response, to the emulation of biological response. In diagnostics, integrated nanodevice biosensors compatible with CMOS technology have achieved unprecedented sensitivity, enabling a wide range of label-free biochemical and macromolecule sensing applications down to femtomolar concentrations. These systems have demonstrated integrated assays of biomarkers at clinically important concentrations for both diagnostics and as a quantitative tool for drug design and discovery. Cellular level response can also be observed, including immune response function and dynamics. Finally, the field is beginning to create devices that emulate function, and the demonstration of a solid state artificial ion channel will be discussed.

Are anticoagulant independent mechanical valves within reach-fast prototype fabrication and in vitro testing of innovative bi-leaflet valve models.

PubMed

Scotten, Lawrence N; Siegel, Rolland

2015-08-01

Exploration for causes of prosthetic valve thrombogenicity has frequently focused on forward or post-closure flow detail. In prior laboratory studies, we uncovered high amplitude flow velocities of short duration close to valve closure implying potential for substantial shear stress with subsequent initiation of blood coagulation pathways. This may be relevant to widely accepted clinical disparity between mechanical and tissue valves vis-à-vis thrombogenicity. With a series of prototype bi-leaflet mechanical valves, we attempt reduction of closure related velocities with the objective of identifying a prototype valve with thrombogenic potential similar to our tissue valve control. This iterative design approach may find application in preclinical assessment of valves for anticoagulation independence. Tested valves included: prototype mechanical bi-leaflet BVs (n=56), controls (n=2) and patented early prototype mechanicals (n=2) from other investigators. Pulsatile and quasi-steady flow systems were used for testing. Projected dynamic valve area (PDVA) was measured using previously described novel technology. Flow velocity over the open and closing periods was determined by volumetric flow rate/PDVA. For the closed valve interval, use was made of data obtained from quasi-steady back pressure/flow tests. Performance was ranked by a proposed thrombogenicity potential index (TPI) relative to tissue and mechanical control valves. Optimization of the prototype valve designs lead to a 3-D printed model (BV3D). For the mitral/aortic site, BV3D has lower TPI (1.10/1.47) relative to the control mechanical valve (3.44/3.93) and similar to the control tissue valve (ideal TPI ≤1.0). Using unique technology, rapid prototyping and thrombogenicity ranking, optimization of experimental valves for reduced thrombogenic potential was expedited and simplified. Innovative mechanical valve configurations were identified that merit consideration for further development which may bring the anti-coagulation independent mechanical valve within reach.

Are anticoagulant independent mechanical valves within reach—fast prototype fabrication and in vitro testing of innovative bi-leaflet valve models

PubMed Central

Siegel, Rolland

2015-01-01

Background Exploration for causes of prosthetic valve thrombogenicity has frequently focused on forward or post-closure flow detail. In prior laboratory studies, we uncovered high amplitude flow velocities of short duration close to valve closure implying potential for substantial shear stress with subsequent initiation of blood coagulation pathways. This may be relevant to widely accepted clinical disparity between mechanical and tissue valves vis-à-vis thrombogenicity. With a series of prototype bi-leaflet mechanical valves, we attempt reduction of closure related velocities with the objective of identifying a prototype valve with thrombogenic potential similar to our tissue valve control. This iterative design approach may find application in preclinical assessment of valves for anticoagulation independence. Methods Tested valves included: prototype mechanical bi-leaflet BVs (n=56), controls (n=2) and patented early prototype mechanicals (n=2) from other investigators. Pulsatile and quasi-steady flow systems were used for testing. Projected dynamic valve area (PDVA) was measured using previously described novel technology. Flow velocity over the open and closing periods was determined by volumetric flow rate/PDVA. For the closed valve interval, use was made of data obtained from quasi-steady back pressure/flow tests. Performance was ranked by a proposed thrombogenicity potential index (TPI) relative to tissue and mechanical control valves. Results Optimization of the prototype valve designs lead to a 3-D printed model (BV3D). For the mitral/aortic site, BV3D has lower TPI (1.10/1.47) relative to the control mechanical valve (3.44/3.93) and similar to the control tissue valve (ideal TPI ≤1.0). Conclusions Using unique technology, rapid prototyping and thrombogenicity ranking, optimization of experimental valves for reduced thrombogenic potential was expedited and simplified. Innovative mechanical valve configurations were identified that merit consideration for further development which may bring the anti-coagulation independent mechanical valve within reach. PMID:26417581

Thrombogenic potential of transcatheter aortic valve implantation with trivial paravalvular leakage

PubMed Central

Siegel, Rolland

2014-01-01

Background Significant paravalvular leakage after transcatheter aortic valve implantation (TAVI) correlates with increased morbidity and mortality, but adverse consequences of trivial paravalvular leakage have stimulated few investigations. Using a unique method distinctly different from other diagnostic approaches, we previously reported elevated backflow velocities of short duration (transients) in mechanical valve closure. In this study, similar transients were found in a transcatheter valve paravalvular leakage avatar. Methods Paravalvular leakage rate (zero to 58 mL/second) and aortic valve incompetence (volumetric back flow/forward flow; zero to 32%) were made adjustable using a mock transcatheter aortic valve device and tested in quasi-steady and pulsatile flow test systems. Projected dynamic valve area (PDVA) from the back illuminated mock transcatheter aortic valve device was measured and regional backflow velocities were derived by dividing volumetric flow rate by the PDVA over the open and closing valve phase and the total closed valve area derived from backflow leakage. Results Aortic incompetence from 1-32% generated negative backflow transients from 8 to 267 meters/second, a range not dissimilar to that measured in mechanical valves with zero paravalvular leakage. Optimal paravalvular leakage was identified; not too small generating high backflow transients, not too large considering volume overload and cardiac energy loss caused by defective valve behavior and fluid motion. Conclusions Thrombogenic potential of transcatheter aortic valves with trivial aortic incompetence and high magnitude regional backflow velocity transients was comparable to mechanical valves. This may have relevance to stroke rate, asymptomatic microembolic episodes and indications for anticoagulation therapy after transcatheter valve insertion. PMID:25333018

Devices as destination therapy.

PubMed

Kukuy, Eugene L; Oz, Mehmet C; Rose, Eric A; Naka, Yoshifumi

2003-02-01

The use of circulatory support as destination therapy has been a goal for the treatment of endstage heart failure for several decades. Current investigations are evaluating several circulatory pumps with that particular objective. With continued modification of design, the current and future pumps will become more reliable and provide improved quality of life to patients in need of mechanical circulatory assistance. The new pumps on the horizon specifically address reliability, size, and cost, and are based on the centrifugal system. These devices use the Maglev (Magnetic Levitation) concept that allows for frictionless pumping, low thrombogenicity, minimal noise, and increased durability. Further research with this goal in mind and support from the federal government will be the key to the future use of circulatory assistance as destination therapy for heart failure patients. In addition, the cost-effectiveness of these devices will need to be maintained as the technology improves, as in any new technology that confronts a more intuitive option like the native heart.

The Amplatzer Vascular Plug: Review of Evolution and Current Applications

PubMed Central

Lopera, Jorge E.

2015-01-01

The Amplatzer Vascular Plug (AVP) was created for peripheral embolization as a modification of the family of Amplatz septal occluders used in the treatment of congenital heart malformations. The device has evolved over the years and multiple versions have been launched into the market. Each of the versions of the device has some important modifications in terms of the size of the introducer's system, number of layers, and resultant thrombogenicity. It is very important for the operator to become familiar with the unique features of the AVP, and to understand the advantages and limitations of each model in the AVP family to achieve an optimal embolic result. The purpose of this article is to review the evolution and current clinical applications of the AVP in the field of interventional radiology, with emphasis on the advantages and limitations of this device in comparison with other embolization agents. PMID:26622098

Biodegradable organic acid-crosslinked alkali-treated gelatins with anti-thrombogenic and endothelialization properties

PubMed Central

Inoue, Motoki; Sasaki, Makoto; Taguchi, Tetsushi

2012-01-01

Gelatins were crosslinked with organic acids and treated with alkali to impart to them endothelialization and anti-thrombogenic properties. These matrices were characterized by biochemical and physicochemical techniques. The amounts of residual amino groups in the matrices decreased with increasing crosslinker concentration. The matrices with the highest crosslinking densities showed excellent endothelial cell adhesion and proliferation. In addition, the adhesion of platelets and formation of fibrin networks on the matrices were suppressed with increasing crosslinker concentration. The matrices also exhibited excellent biodegradability, and the degradation rate decreased with increasing crosslinking density. All the organic acid-crosslinked alkali-treated gelatins showed excellent anti-thrombogenic and endothelialization properties, superior to those of glutaraldehyde-crosslinked alkali-treated gelatins. PMID:27877542

Biocompatibility and hemocompatibility of surface-modified NiTi alloys.

PubMed

Armitage, David A; Parker, Terry L; Grant, David M

2003-07-01

Nickel titanium (NiTi) shape memory alloys have been investigated for several years with regard to biomedical applications. However, little is known about the influences of surface modifications on the biocompatibility of these alloys. The effects of a range of surface treatments were investigated. Cytotoxicity and cytocompatibility studies with both fibroblast and endothelial cells showed no differences in the biocompatibility of any of the NiTi surfaces. The cytotoxicity and cytocompatibility of all surfaces were favorable compared to the controls. The hemolysis caused by a range of NiTi surfaces was no different from that caused by polished 316L stainless steel or polished titanium surfaces. The spreading of platelets has been linked to the thrombogenicity of materials. Platelet studies here showed a significant increase in thrombogenicity on polished NiTi surfaces compared to 316L stainless steel and pure titanium surfaces. Heat treatment of NiTi was found to significantly reduce thrombogenicity, to the level of the control. The XPS results showed a significant decrease in the concentration of surface nickel with heat treatment and changes in the surface nickel itself from a metallic to an oxide state. This correlates with the observed reduction in thrombogenicity. Copyright 2003 Wiley Periodicals, Inc.

Graphics with Special Interfaces for Disabled People.

ERIC Educational Resources Information Center

Tronconi, A.; And Others

The paper describes new software and special input devices to allow physically impaired children to utilize the graphic capabilities of personal computers. Special input devices for computer graphics access--the voice recognition card, the single switch, or the mouse emulator--can be used either singly or in combination by the disabled to control…

Investigation of hyper-NA scanner emulation for photomask CDU performance

NASA Astrophysics Data System (ADS)

Poortinga, Eric; Scheruebl, Thomas; Conley, Will; Sundermann, Frank

2007-02-01

As the semiconductor industry moves toward immersion lithography using numerical apertures above 1.0 the quality of the photomask becomes even more crucial. Photomask specifications are driven by the critical dimension (CD) metrology within the wafer fab. Knowledge of the CD values at resist level provides a reliable mechanism for the prediction of device performance. Ultimately, tolerances of device electrical properties drive the wafer linewidth specifications of the lithography group. Staying within this budget is influenced mainly by the scanner settings, resist process, and photomask quality. Tightening of photomask specifications is one mechanism for meeting the wafer CD targets. The challenge lies in determining how photomask level metrology results influence wafer level imaging performance. Can it be inferred that photomask level CD performance is the direct contributor to wafer level CD performance? With respect to phase shift masks, criteria such as phase and transmission control are generally tightened with each technology node. Are there other photomask relevant influences that effect wafer CD performance? A comprehensive study is presented supporting the use of scanner emulation based photomask CD metrology to predict wafer level within chip CD uniformity (CDU). Using scanner emulation with the photomask can provide more accurate wafer level prediction because it inherently includes all contributors to image formation related to the 3D topography such as the physical CD, phase, transmission, sidewall angle, surface roughness, and other material properties. Emulated images from different photomask types were captured to provide CD values across chip. Emulated scanner image measurements were completed using an AIMS TM45-193i with its hyper-NA, through-pellicle data acquisition capability including the Global CDU Map TM software option for AIMS TM tools. The through-pellicle data acquisition capability is an essential prerequisite for capturing final CDU data (after final clean and pellicle mounting) before the photomask ships or for re-qualification at the wafer fab. Data was also collected on these photomasks using a conventional CD-SEM metrology system with the pellicles removed. A comparison was then made to wafer prints demonstrating the benefit of using scanner emulation based photomask CD metrology.

Surface modification of a biodegradable magnesium alloy with phosphorylcholine (PC) and sulfobetaine (SB) functional macromolecules for reduced thrombogenicity and acute corrosion resistance

PubMed Central

Ye, Sang-Ho; Jang, Yong-Seok; Yun, Yeo-Heung; Shankarraman, Venkat; Woolley, Joshua R.; Hong, Yi; Gamble, Lara J.; Ishihara, Kazuhiko; Wagner, William R.

2013-01-01

Siloxane functionalized phosphorylcholine (PC) or sulfobetaine (SB) macromolecules (PCSSi or SBSSi) were synthesized to act as surface modifying agents for degradable metallic surfaces to improve acute blood compatibility and slow initial corrosion rates. The macromolecules were synthesized using a thiol-ene radical photopolymerization technique and then utilized to modify magnesium (Mg) alloy (AZ31) surfaces via an anhydrous phase deposition of the silane functional groups. X-ray photoelectron spectroscopy surface analysis results indicated successful surface modification based on increased nitrogen and phosphorus or sulfur composition on the modified surfaces relative to unmodified AZ31. In vitro acute thrombogenicity assessment after ovine blood contact with the PCSSi and SBSSi modified surfaces showed a significant decrease in platelet deposition and bulk phase platelet activation compared with the control alloy surfaces. Potentiodynamic polarization and electrochemical impedance spectroscopy data obtained from electrochemical corrosion testing demonstrated increased corrosion resistance for PCSSi and SBSSi modified AZ31 versus unmodified surfaces. The developed coating technique using PCSSi or SBSSi showed promise in acutely reducing both the corrosion and thrombotic processes, which would be attractive for application to blood contacting devices, such as vascular stents, made from degradable Mg alloys. PMID:23705967

Memristors with diffusive dynamics as synaptic emulators for neuromorphic computing

DOE PAGES

Wang, Zhongrui; Joshi, Saumil; Savel’ev, Sergey E.; ...

2016-09-26

The accumulation and extrusion of Ca 2+ in the pre- and postsynaptic compartments play a critical role in initiating plastic changes in biological synapses. In order to emulate this fundamental process in electronic devices, we developed diffusive Ag-in-oxide memristors with a temporal response during and after stimulation similar to that of the synaptic Ca 2+ dynamics. In situ high-resolution transmission electron microscopy and nanoparticle dynamics simulations both demonstrate that Ag atoms disperse under electrical bias and regroup spontaneously under zero bias because of interfacial energy minimization, closely resembling synaptic influx and extrusion of Ca 2+, respectively. Furthermore, the diffusive memristormore » and its dynamics enable a direct emulation of both short- and long-term plasticity of biological synapses, representing an advance in hardware implementation of neuromorphic functionalities.« less

The link between heightened thrombogenicity and inflammation: pre-procedure characterization of the patient at high risk for recurrent events after stenting.

PubMed

Gurbel, Paul A; Bliden, Kevin P; Kreutz, Rolf P; Dichiara, Joseph; Antonino, Mark J; Tantry, Udaya S

2009-03-01

Heightened thrombogenicity and biomarker evidence of inflammation have been independently associated with ischemic risk in patients with coronary artery disease. However, a study examining their relation has not been reported. We analysed the relation between measurements of thrombogenicity and biomarkers in patients undergoing stenting and followed for 24 months recurrent ischemic events. In 84 consecutive patients undergoing stenting, pre-procedure thrombogenicity was measured by thrombelastography (TEG) and conventional aggregometry whereas biomarkers were measured by fluorokine multi-analyte profiling. Patients were stratified into quartiles based on platelet-fibrin clot strength (MA) by TEG and correlated with ischemic event occurrence. Patients in the highest MA quartile (high MA) had greater ADP-induced platelet aggregation (57.5 +/- 15.0% vs. 47.9 +/- 17.6%, p = 0.05), C-reactive protein (25.0 +/- 5.6 vs. 4.2 +/- 1.0 microg/mL, p = 0.006) and interleukin-8 (23.8 +/- 2.8 vs. 14.1 +/- 1.6 pg/mL, p < 0.001) than patients within the lowest MA quartile (low MA). Epidermal growth factor (7.7 +/- 2.2 vs. 1.2 +/- 0.3 pg/mL, p = 0.006) and vascular endothelial growth factor (296 +/- 35 vs. 190 +/- 10 pg/mL, p = 0.05) were also higher. Patients with high-MA had an ischemic event more often than patients with low-MA (48% vs. 13%, p = 0.02). Our study suggests that a link is present between inflammation and heightened thrombogenicity measured pre-procedurally in the patient at high risk for recurrent ischemic events after stenting. Larger studies are required to solidify these observations and their clinical relevance.

Effect of specific surface microstructures on substrate endothelialisation and thrombogenicity: Importance for stent design.

PubMed

Lutter, Christoph; Nothhaft, Matthias; Rzany, Alexander; Garlichs, Christoph D; Cicha, Iwona

2015-01-01

In coronary artery disease, highly stenosed arteries are frequently treated by stent implantation, which thereafter necessitates a dual-antiplatelet therapy (DAPT) in order to prevent stent-thrombosis. We hypothesized that specific patterns of microstructures on stents can accelerate endothelialisation thereby reducing their thrombogenicity and the DAPT duration. Differently designed, 2-5 μm high elevations or hollows were lithographically etched on silicon plates, subsequently coated with silicon carbide. Smooth silicon plates and bare metal substrates were used as controls. To assess attachment and growth of human umbilical vein endothelial cells under static or flow conditions, actin cytoskeleton was visualised with green phalloidin. Endothelial migration was assessed in a modified barrier assay. To investigate surface thrombogenicity, platelets were incubated on the structured surfaces in static and flow conditions, and visualised with fluorescein-conjugated P-selectin antibody. Images were taken with incident-light fluorescent microscope for non-transparent objects. Compared to smooth surface, flat cubic elevations (5 μm edge length) improved endothelial cell attachment and growth under static and dynamic conditions, whereas smaller, spiky structures (2 μm edge length) had a negative influence on endothelialisation. Endothelial cell migration was fastest on flat cubic elevations, hollows, and smooth surfaces, whereas spiky structures and bare metal had a negative effect on endothelial migration. Thrombogenicity assays under static and flow conditions showed that platelet adhesion was reduced on the flat elevations and the smooth surface, as compared to the spiky structures, the hollow design and the bare metal substrates. Surface microstructures strongly influence endothelialisation of substrates. Designing stents with surface topography which accelerates endothelialisation and reduces thrombogenicity may be of clinical benefit by improving the safety profile of coronary interventions.

Proof-of-Concept Evaluation of the SailValve Self-Expanding Deep Venous Valve System in a Porcine Model.

PubMed

Boersma, Doeke; Vink, Aryan; Moll, Frans L; de Borst, Gert J

2017-06-01

To evaluate the SailValve, a new self-expanding deep venous valve concept based on a single polytetrafluoroethylene cusp floating up and down in the bloodstream like a sail, acting as a flow regulator and allowing minimal reflux to reduce thrombogenicity. Both iliac veins of 5 pigs were implanted with SailValve devices; the first animal was an acute pilot experiment to show the feasibility of accurately positioning the SailValve via a femoral access. The other 4 animals were followed for 2 weeks (n=2) or 4 weeks (n=2) under a chronic implantation protocol. Patency and valve function were evaluated directly in all animals using ascending and descending phlebography after device placement and at termination in the chronic implant animals. For reasons of clinical relevance, a regimen of clopidogrel and calcium carbasalate was administered. Histological analysis was performed according to a predefined protocol by an independent pathologist. Deployment was technically feasible in all 10 iliac veins, and all were patent directly after placement. No perioperative or postoperative complications occurred. Ascending phlebograms in the follow-up animals confirmed the patency of all valves after 2 or 4 weeks. Descending phlebograms showed full function in 5 of 8 valves. Limited reflux was seen in 1 valve (4-week group), and the function in the remaining 2 valves (2-week group) was insufficient because of malpositioning. No macroscopic thrombosis was noted on histology. Histology in the follow-up groups revealed a progressive inflammatory reaction to the valves. This animal study shows the potential of the SailValve concept with sufficient valve function after adequate positioning and no (thrombogenic) occlusions after short-term follow-up. Future research is essential to optimize valve material and long-term patency.

Machine Learning and Quantum Mechanics

NASA Astrophysics Data System (ADS)

Chapline, George

The author has previously pointed out some similarities between selforganizing neural networks and quantum mechanics. These types of neural networks were originally conceived of as away of emulating the cognitive capabilities of the human brain. Recently extensions of these networks, collectively referred to as deep learning networks, have strengthened the connection between self-organizing neural networks and human cognitive capabilities. In this note we consider whether hardware quantum devices might be useful for emulating neural networks with human-like cognitive capabilities, or alternatively whether implementations of deep learning neural networks using conventional computers might lead to better algorithms for solving the many body Schrodinger equation.

Proposal for an All-Spin Artificial Neural Network: Emulating Neural and Synaptic Functionalities Through Domain Wall Motion in Ferromagnets.

PubMed

Sengupta, Abhronil; Shim, Yong; Roy, Kaushik

2016-12-01

Non-Boolean computing based on emerging post-CMOS technologies can potentially pave the way for low-power neural computing platforms. However, existing work on such emerging neuromorphic architectures have either focused on solely mimicking the neuron, or the synapse functionality. While memristive devices have been proposed to emulate biological synapses, spintronic devices have proved to be efficient at performing the thresholding operation of the neuron at ultra-low currents. In this work, we propose an All-Spin Artificial Neural Network where a single spintronic device acts as the basic building block of the system. The device offers a direct mapping to synapse and neuron functionalities in the brain while inter-layer network communication is accomplished via CMOS transistors. To the best of our knowledge, this is the first demonstration of a neural architecture where a single nanoelectronic device is able to mimic both neurons and synapses. The ultra-low voltage operation of low resistance magneto-metallic neurons enables the low-voltage operation of the array of spintronic synapses, thereby leading to ultra-low power neural architectures. Device-level simulations, calibrated to experimental results, was used to drive the circuit and system level simulations of the neural network for a standard pattern recognition problem. Simulation studies indicate energy savings by  ∼  100× in comparison to a corresponding digital/analog CMOS neuron implementation.

Storage Media for Microcomputers.

ERIC Educational Resources Information Center

Trautman, Rodes

1983-01-01

Reviews computer storage devices designed to provide additional memory for microcomputers--chips, floppy disks, hard disks, optical disks--and describes how secondary storage is used (file transfer, formatting, ingredients of incompatibility); disk/controller/software triplet; magnetic tape backup; storage volatility; disk emulator; and…

Emulation of Industrial Control Field Device Protocols

DTIC Science & Technology

2013-03-01

platforms such as the Arduino ( based on the Atmel AVR architecture) or popular PIC architecture based devices, which are programmed for specific functions...UNIVERSITY AIR FORCE INSTITUTE OF TECHNOLOGY Wright-Patterson Air Force Base , Ohio DISTRIBUTION STATEMENT A. APPROVED FOR PUBLIC RELEASE; DISTRIBUTION...confidence intervals for the mean. Based on these results, extensive knowledge of the specific implementations of the protocols or timing profiles of the

Relative antithrombotic and antihemostatic effects of protein C activator versus low-molecular-weight heparin in primates

PubMed Central

Marzec, Ulla M.; Bush, Leslie; Di Cera, Enrico; Fernández, José A.; Berny, Michelle A.; Tucker, Erik I.; McCarty, Owen J. T.; Griffin, John H.; Hanson, Stephen R.

2007-01-01

The anticoagulant and anti-inflammatory enzyme, activated protein C (APC), naturally controls thrombosis without affecting hemostasis. We therefore evaluated whether the integrity of primary hemostasis was preserved during limited pharmacological antithrombotic protein C activator (PCA) treatment in baboons. The double-mutant thrombin (Trp215Ala/Glu217Ala) with less than 1% procoagulant activity was used as a relatively selective PCA and compared with systemic anticoagulation by APC and low-molecular-weight heparin (LMWH) at doses that inhibited fibrin deposition on thrombogenic segments of arteriovenous shunts. As expected, both systemic anticoagulants, APC (0.028 or 0.222 mg/kg for 70 minutes) and LMWH (0.325 to 2.6 mg/kg for 70 minutes), were antithrombotic and prolonged the template bleeding time. In contrast, PCA at doses (0.0021 to 0.0083 mg/kg for 70 minutes) that had antithrombotic effects comparable with LMWH did not demonstrably impair primary hemostasis. PCA bound to platelets and leukocytes, and accumulated in thrombi. APC infusion at higher circulating APC levels was less antithrombotic than PCA infusion at lower circulating APC levels. The observed dissociation of antithrombotic and antihemostatic effects during PCA infusion thus appeared to emulate the physiological regulation of intravascular blood coagulation (thrombosis) by the endogenous protein C system. Our data suggest that limited pharmacological protein C activation might exhibit considerable thrombosis specificity. PMID:17227834

Compliance-Free, Digital SET and Analog RESET Synaptic Characteristics of Sub-Tantalum Oxide Based Neuromorphic Device.

PubMed

Abbas, Yawar; Jeon, Yu-Rim; Sokolov, Andrey Sergeevich; Kim, Sohyeon; Ku, Boncheol; Choi, Changhwan

2018-01-19

A two terminal semiconducting device like a memristor is indispensable to emulate the function of synapse in the working memory. The analog switching characteristics of memristor play a vital role in the emulation of biological synapses. The application of consecutive voltage sweeps or pulses (action potentials) changes the conductivity of the memristor which is considered as the fundamental cause of the synaptic plasticity. In this study, a neuromorphic device using an in-situ growth of sub-tantalum oxide switching layer is fabricated, which exhibits the digital SET and analog RESET switching with an electroforming process without any compliance current (compliance free). The process of electroforming and SET is observed at the positive sweeps of +2.4 V and +0.86 V, respectively, while multilevel RESET is observed with the consecutive negative sweeps in the range of 0 V to -1.2 V. The movement of oxygen vacancies and gradual change in the anatomy of the filament is attributed to digital SET and analog RESET switching characteristics. For the Ti/Ta 2 O 3-x /Pt neuromorphic device, the Ti top and Pt bottom electrodes are considered as counterparts of the pre-synaptic input terminal and a post-synaptic output terminal, respectively.

Development of a Radio Frequency Space Environment Path Emulator for Evaluating Spacecraft Ranging Hardware

NASA Technical Reports Server (NTRS)

Mitchell, Jason W.; Baldwin, Philip J.; Kurichh, Rishi; Naasz, Bo J.; Luquette, Richard J.

2007-01-01

The Formation Flying Testbed (FFTB) at the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) provides a hardware-in-the-loop test environment for formation navigation and control. The facility is evolving as a modular, hybrid, dynamic simulation facility for end-to-end guidance, navigation and. control (GN&C) design and analysis of formation flying spacecraft. The core capabilities of the FFTB, as a platform for testing critical hardware and software algorithms in-the-loop, have expanded to include S-band Radio Frequency (RF) modems for inter-spacecraft communication and ranging. To enable realistic simulations that require RF ranging sensors for relative navigation, a mechanism is needed to buffer the RF signals exchanged between spacecraft that accurately emulates the dynamic environment through which the RF signals travel, including the effects of medium, moving platforms, and radiated power. The Path Emulator for RF Signals (PERFS), currently under development at NASA GSFC, provides this capability. The function and performance of a prototype device are presented.

Characterization of a Prototype Radio Frequency Space Environment Path Emulator for Evaluating Spacecraft Ranging Hardware

NASA Technical Reports Server (NTRS)

Mitchell, Jason W.; Baldwin, Philip J.; Kurichh, Rishi; Naasz, Bo J.; Luquette, Richard J.

2007-01-01

The Formation Flying Testbed (FFTB) at the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) provides a hardware-in-the-loop test environment for formation navigation and control. The facility is evolving as a modular, hybrid, dynamic simulation facility for end-to-end guidance, navigation and control (GN&C) design and analysis of formation flying spacecraft. The core capabilities of the FFTB, as a platform for testing critical hardware and software algorithms in-the-loop, have expanded to include S-band Radio Frequency (RF) modems for interspacecraft communication and ranging. To enable realistic simulations that require RF ranging sensors for relative navigation, a mechanism is needed to buffer the RF signals exchanged between spacecraft that accurately emulates the dynamic environment through which the RF signals travel, including the effects of the medium, moving platforms, and radiated power. The Path Emulator for Radio Frequency Signals (PERFS), currently under development at NASA GSFC, provides this capability. The function and performance of a prototype device are presented.

Biorobotics: using robots to emulate and investigate agile locomotion.

PubMed

Ijspeert, Auke J

2014-10-10

The graceful and agile movements of animals are difficult to analyze and emulate because locomotion is the result of a complex interplay of many components: the central and peripheral nervous systems, the musculoskeletal system, and the environment. The goals of biorobotics are to take inspiration from biological principles to design robots that match the agility of animals, and to use robots as scientific tools to investigate animal adaptive behavior. Used as physical models, biorobots contribute to hypothesis testing in fields such as hydrodynamics, biomechanics, neuroscience, and prosthetics. Their use may contribute to the design of prosthetic devices that more closely take human locomotion principles into account. Copyright © 2014, American Association for the Advancement of Science.

Un modèle mathématique décrivant le changement du caractère constitutif du sang dû à l'activation des plaquettes

NASA Astrophysics Data System (ADS)

Anand, Mohan; Rajagopal, Kumbakonam R.

Though a minor component by volume, platelets can have a profound influence on the flow characteristics of blood and thereby have serious consequences with regard to cardiovascular functions. Platelets are extremely sensitive to chemical agents as well as mechanical inputs and platelet activation is a necessary precursor to many life threatening medical conditions such as acute myocardial infarction, most strokes, acute arterial occlusion, venous thrombosis and pulmonary embolism. In cardiovascular devices such as ventricular assist devices and prosthetic heart valves, high shear stresses can trigger platelet activation. Moreover, such devices have artificial surfaces that are thrombogenic, the thrombotic deposition contributing to the failure of the device. Thus, there is a need to develop a mathematical model for the flow of blood that takes into account platelet activation, no such model being available at the moment. While there has been considerable amount of work in blood rheology, the role of platelets in the flow characteristics of blood has been largely ignored. This study addresses this lacuna. To cite this article: M. Anand, K.R. Rajagopal, C. R. Mecanique 330 (2002) 557-562.

Tailoring the surface properties of polypropylene films through cold atmospheric pressure plasma (CAPP) assisted polymerization and immobilization of biomolecules for enhancement of anti-coagulation activity

NASA Astrophysics Data System (ADS)

Navaneetha Pandiyaraj, K.; Ram Kumar, M. C.; Arun Kumar, A.; Padmanabhan, P. V. A.; Deshmukh, R. R.; Bah, M.; Ismat Shah, S.; Su, Pi-Guey; Halleluyah, M.; Halim, A. S.

2016-05-01

Enhancement of anti-thrombogenic properties of polypropylene (PP) to avert the adsorption of plasma proteins (fibrinogen and albumin), adhesion and activation of the platelets are very important for vast biomedical applications. The cold atmospheric pressure plasma (CAPP) assisted polymerization has potential to create the specific functional groups such as Osbnd Cdbnd O, Cdbnd O, Csbnd N and Ssbnd S. on the surface of polymeric films using selective precursor in vapour phase to enhance anti-thrombogenic properties. Such functionalized polymeric surfaces would be suitable for various biomedical applications especially to improve the blood compatibility. The eventual aspiration of the present investigation is to develop the biofunctional coating onto the surface of PP films using acrylic acid (AAc) and polyethylene glycol (PEG) as a precursor in a vapour phase by incorporating specific functional groups for immobilization of biomolecules such as heparin (HEP), chitosan (CHI) and insulin (INS) on the surface of plasma modified PP films. The surface properties such as hydrophilicity, chemical composition, surface topography of the surface modified PP films were analyzed by contact angle (CA), Fourier transform infrared spectroscopy (FTIR), X-ray photo electron spectroscopy (XPS) and atomic force microscopy (AFM). Furthermore the anti-thrombogenic properties of the surface modified PP films were studied by in vitro tests which include platelet adhesion and protein adsorption analysis. It was found that the anti-thrombogenic properties of the PP films are effectively controlled by the CAPP grafting of AAc and PEG followed by immobilization of biomolecules of heparin, chitosan and insulin. The grafting and immobilization was confirmed by FTIR and XPS through the recognition of specific functional groups such as COOH, Csbnd O, Ssbnd S and Csbnd N. on the surface of PP film. Furthermore, the surface morphology and hydrophilic nature of the PP films also tailored significantly by the successful grafting and immobilization which is confirmed by AFM and CA analysis. Owing to the physico-chemical changes on the surface of PP films induced by CAPP assisted polymerization, the anti-thrombogenic properties of PP films were enhanced as confirmed by in vitro analysis.

The thrombogenicity of C1 esterase inhibitor (human): review of the evidence.

PubMed

Crowther, Mark; Bauer, Kenneth A; Kaplan, Allen P

2014-01-01

Thromboembolic events associated with human plasma-derived C1 esterase inhibitor (C1-INH) use in patients with hereditary angioedema (HAE) have been reported in the U.S. Food and Drug Administration (FDA) Adverse Event Reporting System database. The purpose of this article is to review and assess the strength of available evidence regarding the thrombogenicity of human plasma-derived C1-INH. A PubMed search was conducted of English language articles from January 1990 to December 2013 reporting the thrombogenicity of C1-INH. Original research articles were selected if the following criteria were met: (1) C1-INH was the focus of the study and (2) the authors addressed the pro- or antithrombotic potential of C1-INH. Additional articles on the clinical use of C1-INH in disease states other than HAE were obtained using reference lists of selected articles. Pivotal studies and prescribing information for C1-INH products were also reviewed. Limited animal and clinical data suggest that C1-INH, particularly at high doses of up to 500 U/kg (compared with the U.S. FDA-approved 20-U/kg dose), may be prothrombotic. In contrast, C1-INH has been used in some patients with myocardial infarction, ischemic stroke, sepsis, and capillary leak syndrome at off-label supratherapeutic doses (up to 100 U/kg) without evidence of a thrombogenic effect. Based on our review, thromboembolic events reported with C1-INH use are rare and patients with HAE who experienced such events often have underlying thromboembolic risk factors.

Race and sex differences in thrombogenicity: risk of ischemic events following coronary stenting.

PubMed

Gurbel, Paul A; Bliden, Kevin P; Cohen, Eli; Navickas, Irene A; Singla, Anand; Antonino, Mark J; Fissha, Mulugeta; Kreutz, Rolf P; Bassi, Ashwani K; Tantry, Udaya S

2008-06-01

Race and sex affect thrombogenicity. We have demonstrated that platelet-fibrin clot characteristics can be used to stratify patients for risk of ischemic events following percutaneous coronary intervention. We investigated race and sex differences in thrombogenicty and the relation to ischemic risk in 252 consecutive African-American and Caucasian men and women undergoing elective percutaneous coronary intervention. Platelet-fibrin clot characteristics were measured using the Thrombelastograph Hemostasis System. The incidence of adverse ischemic events was assessed over a 6-month follow-up period. Overall, 40 ischemic events (15.9%) occurred. Adverse events were higher in African-Americans than Caucasians (P = 0.14), and in women than men (P = 0.004). The incidence was highest in African-American women (37.5%) and lowest in African-American men (6.5%). Measured Thrombelastograph parameters were significantly different between ischemic and nonischemic patients (P < 0.05). African-American women in the ischemic group exhibited higher thrombogenicity than the other race and sex groups (P < 0.05). Multivariate logistic regression identified platelet-fibrin mediated clot strength (relative risk 2.52, P = 0.017) and sex (relative risk 2.56, P = 0.009) as significant independent predictors of ischemic events 6 months postpercutaneous coronary intervention. Thrombogenicity is a novel measurable cardiovascular risk factor that varies by race and sex, is highest in African-American women, and independently predicts the frequency of ischemic events following percutaneous coronary intervention. Point-of-service measurements of platelet-fibrin clot characteristics may lead to more intensified antithrombotic therapy and reduced mortality in selected patients.

Limitations of Segmented Wavefront Control Devices in Emulating Optical Turbulence

DTIC Science & Technology

2008-03-01

have been manipulated into a grid of phase values with the same properties as the atmosphere they represent. The method used in this research to... research comes to fruition. Therefore, another method must be found for the relationship between r0imin and Fmax which is investigated in Section 3.2.3. 36...several available commercial devices are better understood as a result of this research . iv Acknowledgements I would like to thank the Air Force Institute

Photoletter to the editor: Diffuse cocaine-related purpura.

PubMed

Sarkar, Debjeet; Kammona, Hussein A; Lamsen, Leonard N; McAbee, Bradley A; Clark, Christopher T; Lee, Solomon S; Kelley, Shane E

2013-01-01

Diffuse purpura is an uncommon skin manifestation found in platelet and coagulation disorders, meningococcemia, vasculitides and cocaine use. Reports of cocaine-related purpura predominantly involve adulteration with the anti-helminthic, levamisole. Levamisole enhances the effects of cocaine and is known to cause vasculitis. Recently, the CDC also released an advisory of oxymorphone being used intravenously causing thrombogenic thrombocytopenic purpura (TTP). We report the case of a patient with diffuse purpura ultimately diagnosed with cocaine-related thrombogenic vasculopathy. In the current environment of adulterated cocaine usage and increased prescription narcotic abuse, it is crucial to investigate substance abuse as a cause of diffuse purpura.

First US experience with Pipeline Flex with Shield Technology using aspirin as antiplatelet monotherapy.

PubMed

Hanel, Ricardo A; Aguilar-Salinas, Pedro; Brasiliense, Leonardo Bc; Sauvageau, Eric

2017-05-04

Flow diversion has revolutionised the treatment of intracranial aneurysms, and the Pipeline Embolization Device (PED) remains the only flow diverter (FD) approved in the USA. However, thromboembolic events remain an issue for FDs. Attempting to minimise these incidents, a newer PED has been developed with the use of covalent bonding of phosphorylcholine onto the Pipeline device that has been known as Shield Technology (PED Shield), which in vitro has demonstrated a significant reduction in material thrombogenicity. We report the first US experience of the PED Shield in the treatment of a ruptured fusiform aneurysm located in the right vertebral artery in an attempt to mitigate complications related to the use of dual-antiplatelet therapy and discuss our rationale for using the new FD, using aspirin only as the antiplatelet regimen. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

In situ regeneration of bioactive coatings enabled by an evolved Staphylococcus aureus sortase A

NASA Astrophysics Data System (ADS)

Ham, Hyun Ok; Qu, Zheng; Haller, Carolyn A.; Dorr, Brent M.; Dai, Erbin; Kim, Wookhyun; Liu, David R.; Chaikof, Elliot L.

2016-04-01

Surface immobilization of bioactive molecules is a central paradigm in the design of implantable devices and biosensors with improved clinical performance capabilities. However, in vivo degradation or denaturation of surface constituents often limits the long-term performance of bioactive films. Here we demonstrate the capacity to repeatedly regenerate a covalently immobilized monomolecular thin film of bioactive molecules through a two-step stripping and recharging cycle. Reversible transpeptidation by a laboratory evolved Staphylococcus aureus sortase A (eSrtA) enabled the rapid immobilization of an anti-thrombogenic film in the presence of whole blood and permitted multiple cycles of film regeneration in vitro that preserved its biological activity. Moreover, eSrtA transpeptidation facilitated surface re-engineering of medical devices in situ after in vivo implantation through removal and restoration film constituents. These studies establish a rapid, orthogonal and reversible biochemical scheme to regenerate selective molecular constituents with the potential to extend the lifetime of bioactive films.

Enhanced endothelial cell density on NiTi surfaces with sub-micron to nanometer roughness

PubMed Central

Samaroo, Harry D; Lu, Jing; Webster, Thomas J

2008-01-01

The shape memory effect and superelastic properties of NiTi (or Nitinol, a nickel-titanium alloy) have already attracted much attention for various biomedical applications (such as vascular stents, orthodontic wires, orthopedic implants, etc). However, for vascular stents, conventional approaches have required coating NiTi with anti-thrombogenic or anti-inflammatory drug-eluting polymers which as of late have proven problematic for healing atherosclerotic blood vessels. Instead of focusing on the use of drug-eluting anti-thrombogenic or anti-inflammatory proteins, this study focused on promoting the formation of a natural anti-thrombogenic and anti-inflammatory surface on metallic stents: the endothelium. In this study, we synthesized various NiTi substrates with different micron to nanometer surface roughness by using dissimilar dimensions of constituent NiTi powder. Endothelial cell adhesion on these compacts was compared with conventional commercially pure (cp) titanium (Ti) samples. The results after 5 hrs showed that endothelial cells adhered much better on fine grain (<60 μm) compared with coarse grain NiTi compacts (<100 μm). Coarse grain NiTi compacts and conventional Ti promoted similar levels of endothelial cell adhesion. In addition, cells proliferated more after 5 days on NiTi with greater sub-micron and nanoscale surface roughness compared with coarse grain NiTi. In this manner, this study emphasized the positive pole that NiTi with sub-micron to nanometer surface features can play in promoting a natural anti-thrombogenic and anti-inflammatory surface (the endothelium) on a vascular stent and, thus, suggests that more studies should be conducted on NiTi with sub-micron to nanometer surface features. PMID:18488418

Effects of amount and type of dietary fats on postprandial lipemia and thrombogenic markers in individuals with metabolic syndrome.

PubMed

Teng, Kim-Tiu; Chang, Chee-Yan; Kanthimathi, M S; Tan, Alexander Tong Boon; Nesaretnam, Kalanithi

2015-09-01

Postprandial lipemia has been reported to affect endothelial function by thrombogenic and inflammatory pathways. We set out to investigate the impact of a) specific amount (50 g vs 20 g fat), and b) type of fatty acids (saturated, monounsaturated or n-6 polyunsaturated fatty acids; SFA, MUFA, PUFA) on postprandial lipemia, thrombogenic and inflammatory factors in metabolic syndrome subjects. 30 subjects (15 men, 15 women) participated in a double-blind, randomized crossover design study with both the subjects and investigators blinded to treatments. Blood samples were collected at fasting and 30 min, hourly interval for a total of 6 h. As expected, lower triacylglycerol response was observed for low fat/high carbohydrate meal; whereas no difference was detected between the types of fatty acids. The incremental area under the curve (iAUC) for low fat/high carbohydrate meal was 70%, 81% and 61% lower than the SFA, MUFA and PUFA meals, respectively. The iAUC 0-6 h for triacylglycerol was 42% lower in women compared with the men (P = 0.024), with the similar trend observed for non-esterified fatty acids. There were significant meal × time interaction (P = 0.000) for plasma plasminogen activator inhibitor-1 and thromboxane B2 (P = 0.022) from baseline. No differences were observed between meals for plasma D-dimer, interleukin-6, interleukin-1β, tumor necrosis factor-α and high sensitivity C-reactive protein. These data indicate that in metabolic syndrome subjects, only the amount of dietary fatty acids affects postprandial lipemia but both amount and type of dietary fats alter thrombogenic factors. The study was registered at Clinicaltrials.gov (NCT01571947). Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

The AN69 ST haemodialysis membrane under conditions of two different extracorporeal circuit rinse protocols a comparison of thrombogenicity parameters.

PubMed

Richtrova, Pavlina; Opatrny, Karel; Vit, Ladislav; Sefrna, Frantisek; Perlik, Radek

2007-10-01

Thrombogenicity is an important parameter of haemodialysis (HD) membrane biocompatibility. The surface of the polyacrylonitrile AN69 ST membrane is coated with a polyethylenimine. This modification allows heparin adsorption. The binding of heparin to the membrane surface occurs during priming of the extracorporeal circuit (ECC) by rinsing it with saline and heparin. Our aims were to assess and compare the thrombogenicity of the AN69 ST membrane under conditions of two extracorporeal circuit (ECC) rinse protocols-with and without unfractionated heparin (UFH). In a prospective, crossover and randomized study, we examined 10 patients during HD after ECC preparation with either rinse protocols. Prior to HD and at 15, 60 and 240 min, we determined plasma levels of the thrombin-antithrombin complexes (TAT), platelet factor 4 (PF4), heparin concentration (antiXa) and thrombocyte count. Systemic anticoagulation was performed using UFH. During HD after ECC rinse without UFH, there was a significantly earlier and more marked increase in TAT compared with UFH-containing rinse (P <0.05). Using Spearman coefficient, we demonstrated a significant correlation between TAT and antiXa at 60 min (r = -0.534) and 240 min (r = -0.538). A comparison of the TAT/antiXa ratios between rinses at 60 min revealed a significantly higher increase in TAT following UFH-free rinse (P <0.05). There was no difference in PF4 between the rinses. Platelet count did not change significantly during HD using either rinse protocol. Based on plasma TAT levels, ECC priming with an UFH-containing solution reduces the thrombogenicity of the AN69 ST membrane. There is no significant difference between both types of priming concerning PF4 and thrombocyte count.

Introduction to multiprotocol over ATM (MPOA)

NASA Astrophysics Data System (ADS)

Fredette, Andre N.

1997-10-01

Multiprotocol over ATM (MPOA) is a new protocol specified by the ATM Forum. MPOA provides a framework for effectively synthesizing bridging and routing with ATM in an environment of diverse protocols and network technologies. The primary goal of MPOA is the efficient transfer of inter-subnet unicast data in a LAN Emulation (LANE) environment. MPOA integrates LANE and the next hop resolution protocol (NHRP) to preserve the benefits of LAN Emulation, while allowing inter-subnet, internetwork layer protocol communication over ATM VCCs without requiring routers in the data path. It reduces latency and the internetwork layer forwarding load on backbone routers by enabling direct connectivity between ATM-attached edge devices (i.e., shortcuts). To establish these shortcuts, MPOA uses both routing and bridging information to locate the edge device closest to the addressed end station. By integrating LANE and NHRP, MPOA allows the physical separation of internetwork layer route calculation and forwarding, a technique known as virtual routing. This separation provides a number of key benefits including enhanced manageability and reduced complexity of internetwork layer capable edge devices. This paper provides an overview of MPOA that summarizes the goals, architecture, and key attributes of the protocol. In presenting this overview, the salient attributes of LANE and NHRP are described as well.

Cyber-Physical System Security With Deceptive Virtual Hosts for Industrial Control Networks

DOE PAGES

Vollmer, Todd; Manic, Milos

2014-05-01

A challenge facing industrial control network administrators is protecting the typically large number of connected assets for which they are responsible. These cyber devices may be tightly coupled with the physical processes they control and human induced failures risk dire real-world consequences. Dynamic virtual honeypots are effective tools for observing and attracting network intruder activity. This paper presents a design and implementation for self-configuring honeypots that passively examine control system network traffic and actively adapt to the observed environment. In contrast to prior work in the field, six tools were analyzed for suitability of network entity information gathering. Ettercap, anmore » established network security tool not commonly used in this capacity, outperformed the other tools and was chosen for implementation. Utilizing Ettercap XML output, a novel four-step algorithm was developed for autonomous creation and update of a Honeyd configuration. This algorithm was tested on an existing small campus grid and sensor network by execution of a collaborative usage scenario. Automatically created virtual hosts were deployed in concert with an anomaly behavior (AB) system in an attack scenario. Virtual hosts were automatically configured with unique emulated network stack behaviors for 92% of the targeted devices. The AB system alerted on 100% of the monitored emulated devices.« less

Interventricular membranous septal aneurysm: CT and MR manifestations.

PubMed

Carcano, Carolina; Kanne, Jeffrey P; Kirsch, Jacobo

2016-02-01

Advanced cardiac imaging is a valuable method to investigate cardiac malformations. The detection of the interventricular membranous septum has clinical significance due to thrombogenic and arrythmogenic predisposition, as well as a role in obstructing the pulmonary flow. This review describes six clinical presentations in which advanced cardiac imaging has been the tool for evaluation, with special emphasis in CT angiography and cardiac MRI sequences. Teaching Points • The interventricular membranous septum can predispose patients to thrombogenic and arrythmogenic events. • Subpulmonic stenosis relates to the protrusion of the aneurysm into the right ventricle • During surgery, ventricular pressures of the opened heart become balanced, making the aneurysm less evident.

Nanomedicine for the reduction of the thrombogenicity of stent coatings

PubMed Central

Karagkiozaki, Varvara C; Logothetidis, Stergios D; Kassavetis, Spyridon N; Giannoglou, George D

2010-01-01

The treatment of patients with drug-eluting stents (DES) continues to evolve with the current emergence of DES technology that offers a combination of pharmacological and mechanical approaches to prevent arterial restenosis. However, despite the promising short-term and mid-term outcomes of DES, there are valid concerns about adverse clinical effects of late stent thrombosis. In this study, we present an example of how nanomedicine can offer solutions for improving stent coating manufacturing, by producing nanomaterials with tailored and controllable properties. The study is based on the exploitation of human platelets response towards carbon-based nanocoatings via atomic force microscope (AFM). AFM can facilitate the comprehensive analysis of platelets behavior onto stent nanocoatings and enable the study of thrombogenicity. Platelet-rich plasma from healthy donors was used for the real-time study of biointerfacial interactions. The carbon nanomaterials were developed by rf magnetron sputtering technique under controllable deposition conditions to provide favorable surface nanotopography. It was shown that by altering the surface topography of nanocoatings, the activation of platelets can be affected, while the carbon nanocoatings having higher surface roughness were found to be less thrombogenic in terms of platelets adhesion. This is an actual solution for improving the stent coating fabrication. PMID:20463940

Influence de revetements bioactifs sur les cellules endotheliales: Vers des protheses vasculaires non thrombotiques

NASA Astrophysics Data System (ADS)

Fadlallah, Hicham

Developing vascular prostheses of small diameter to replace vessels closed by atherosclerosis remains a challenge because of the risk of thrombosis. Seeding of endothelial cells, which have antithrombogenic properties, is a promising solution, but we must create surfaces which promote their adhesion and retention to resist shear stresses created by the blood flow on the surface. This master's project aimed at investigating the effect of a plasma polymerized coating rich in primary amines (called LP), with or without elements of the extracellular matrix (Fibronectin (FN) or chondroitin sulphate (CS)) on the endothelial cells and hemocompatibility of polyethylene terephthalate (PET). The adhesion, growth and retention of human umbilical vein endothelial cells (HUVECs) on PET and LP, in the presence and absence of FN or CS, have been studied. In addition, platelet adhesion on different surfaces was evaluated by a perfusion test with whole blood, platelets being previously labeled with rhodamine. Finally a double fluorescent labeling (using Cellview Maroon to mark the HUVECs and CD61 antibody for platelets) was developed to study the retention of endothelial cells, under blood flow and verify their non thrombogenic character. The results obtained show that both the LP coating and the adsorbed FN, strongly increase both the cellular adhesion and growth on PET; however they have no additional effect when the two are combined. They also augment cellular retention to surface, but this remains incomplete. Moreover we observed that the plasma coating (LP) greatly increases the thrombogenicity of the surface, with strong platelet adhesion and activation. This thrombogenicity is extremely reduced when endothelial cells cover the surface, but cell loss under the effect of shear produced by the perfusion creates significant areas of platelet adhesion. The grafting of CS on LP also permits good HUVECs adhesion, growth and retention under shear stress on HUVEC, with no difference from the LP alone. In addition, the CS sharply decreases the platelet adhesion, which is found below the value observed for PET. The double cell labeling also showed that cells adhered on LP+CS has an anti-thrombotic phenotype and can resist blood flow. These studies suggest that a coating of CS is a promising strategy for vascular prosthesis given the combination of the good adhesion of endothelial cells and the low thrombogenicity of the underlying surface. Keywords: vascular prostheses, polymers, bioactive coating, thrombogenicity, HUVECs.

High fidelity computational simulation of thrombus formation in Thoratec HeartMate II continuous flow ventricular assist device

PubMed Central

Wu, Wei-Tao; Yang, Fang; Wu, Jingchun; Aubry, Nadine; Massoudi, Mehrdad; Antaki, James F.

2016-01-01

Continuous flow ventricular assist devices (cfVADs) provide a life-saving therapy for severe heart failure. However, in recent years, the incidence of device-related thrombosis (resulting in stroke, device-exchange surgery or premature death) has been increasing dramatically, which has alarmed both the medical community and the FDA. The objective of this study was to gain improved understanding of the initiation and progression of thrombosis in one of the most commonly used cfVADs, the Thoratec HeartMate II. A computational fluid dynamics simulation (CFD) was performed using our recently updated mathematical model of thrombosis. The patterns of deposition predicted by simulation agreed well with clinical observations. Furthermore, thrombus accumulation was found to increase with decreased flow rate, and can be completely suppressed by the application of anticoagulants and/or improvement of surface chemistry. To our knowledge, this is the first simulation to explicitly model the processes of platelet deposition and thrombus growth in a continuous flow blood pump and thereby replicate patterns of deposition observed clinically. The use of this simulation tool over a range of hemodynamic, hematological, and anticoagulation conditions could assist physicians to personalize clinical management to mitigate the risk of thrombosis. It may also contribute to the design of future VADs that are less thrombogenic. PMID:27905492

A pilot study comparing mouse and mouse-emulating interface devices for graphic input.

PubMed

Kanny, E M; Anson, D K

1991-01-01

Adaptive interface devices make it possible for individuals with physical disabilities to use microcomputers and thus perform many tasks that they would otherwise be unable to accomplish. Special equipment is available that purports to allow functional access to the computer for users with disabilities. As technology moves from purely keyboard applications to include graphic input, it will be necessary for assistive interface devices to support graphics as well as text entry. Headpointing systems that emulate the mouse in combination with on-screen keyboards are of particular interest to persons with severe physical impairment such as high level quadriplegia. Two such systems currently on the market are the HeadMaster and the Free Wheel. The authors have conducted a pilot study comparing graphic input speed using the mouse and two headpointing interface systems on the Macintosh computer. The study used a single subject design with six able-bodied subjects, to establish a baseline for comparison with persons with severe disabilities. Results of these preliminary data indicated that the HeadMaster was nearly as effective as the mouse and that it was superior to the Free Wheel for graphics input. This pilot study, however, demonstrated several experimental design problems that need to be addressed to make the study more robust. It also demonstrated the need to include the evaluation of text input so that the effectiveness of the interface devices with text and graphic input could be compared.

On Emulation of Flueric Devices in Excitable Chemical Medium

PubMed Central

Adamatzky, Andrew

2016-01-01

Flueric devices are fluidic devices without moving parts. Fluidic devices use fluid as a medium for information transfer and computation. A Belousov-Zhabotinsky (BZ) medium is a thin-layer spatially extended excitable chemical medium which exhibits travelling excitation wave-fronts. The excitation wave-fronts transfer information. Flueric devices compute via jets interaction. BZ devices compute via excitation wave-fronts interaction. In numerical model of BZ medium we show that functions of key flueric devices are implemented in the excitable chemical system: signal generator, and, xor, not and nor Boolean gates, delay elements, diodes and sensors. Flueric devices have been widely used in industry since late 1960s and are still employed in automotive and aircraft technologies. Implementation of analog of the flueric devices in the excitable chemical systems opens doors to further applications of excitation wave-based unconventional computing in soft robotics, embedded organic electronics and living technologies. PMID:27997561

On Emulation of Flueric Devices in Excitable Chemical Medium.

PubMed

Adamatzky, Andrew

2016-01-01

Flueric devices are fluidic devices without moving parts. Fluidic devices use fluid as a medium for information transfer and computation. A Belousov-Zhabotinsky (BZ) medium is a thin-layer spatially extended excitable chemical medium which exhibits travelling excitation wave-fronts. The excitation wave-fronts transfer information. Flueric devices compute via jets interaction. BZ devices compute via excitation wave-fronts interaction. In numerical model of BZ medium we show that functions of key flueric devices are implemented in the excitable chemical system: signal generator, and, xor, not and nor Boolean gates, delay elements, diodes and sensors. Flueric devices have been widely used in industry since late 1960s and are still employed in automotive and aircraft technologies. Implementation of analog of the flueric devices in the excitable chemical systems opens doors to further applications of excitation wave-based unconventional computing in soft robotics, embedded organic electronics and living technologies.

Vehicle electrical system state controller

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bissontz, Jay E.

A motor vehicle electrical power distribution system includes a plurality of distribution sub-systems, an electrical power storage sub-system and a plurality of switching devices for selective connection of elements of and loads on the power distribution system to the electrical power storage sub-system. A state transition initiator provides inputs to control system operation of switching devices to change the states of the power distribution system. The state transition initiator has a plurality of positions selection of which can initiate a state transition. The state transition initiator can emulate a four position rotary ignition switch. Fail safe power cutoff switches providemore » high voltage switching device protection.« less

Short-term plasticity and long-term potentiation mimicked in single inorganic synapses

NASA Astrophysics Data System (ADS)

Ohno, Takeo; Hasegawa, Tsuyoshi; Tsuruoka, Tohru; Terabe, Kazuya; Gimzewski, James K.; Aono, Masakazu

2011-08-01

Memory is believed to occur in the human brain as a result of two types of synaptic plasticity: short-term plasticity (STP) and long-term potentiation (LTP; refs , , , ). In neuromorphic engineering, emulation of known neural behaviour has proven to be difficult to implement in software because of the highly complex interconnected nature of thought processes. Here we report the discovery of a Ag2S inorganic synapse, which emulates the synaptic functions of both STP and LTP characteristics through the use of input pulse repetition time. The structure known as an atomic switch, operating at critical voltages, stores information as STP with a spontaneous decay of conductance level in response to intermittent input stimuli, whereas frequent stimulation results in a transition to LTP. The Ag2S inorganic synapse has interesting characteristics with analogies to an individual biological synapse, and achieves dynamic memorization in a single device without the need of external preprogramming. A psychological model related to the process of memorizing and forgetting is also demonstrated using the inorganic synapses. Our Ag2S element indicates a breakthrough in mimicking synaptic behaviour essential for the further creation of artificial neural systems that emulate characteristics of human memory.

Circling motion and screen edges as an alternative input method for on-screen target manipulation.

PubMed

Ka, Hyun W; Simpson, Richard C

2017-04-01

To investigate a new alternative interaction method, called circling interface, for manipulating on-screen objects. To specify a target, the user makes a circling motion around the target. To specify a desired pointing command with the circling interface, each edge of the screen is used. The user selects a command before circling the target. To evaluate the circling interface, we conducted an experiment with 16 participants, comparing the performance on pointing tasks with different combinations of selection method (circling interface, physical mouse and dwelling interface) and input device (normal computer mouse, head pointer and joystick mouse emulator). A circling interface is compatible with many types of pointing devices, not requiring physical activation of mouse buttons, and is more efficient than dwell-clicking. Across all common pointing operations, the circling interface had a tendency to produce faster performance with a head-mounted mouse emulator than with a joystick mouse. The performance accuracy of the circling interface outperformed the dwelling interface. It was demonstrated that the circling interface has the potential as another alternative pointing method for selecting and manipulating objects in a graphical user interface. Implications for Rehabilitation A circling interface will improve clinical practice by providing an alternative pointing method that does not require physically activating mouse buttons and is more efficient than dwell-clicking. The Circling interface can also work with AAC devices.

Electrode geometry for electrostatic generators and motors

DOEpatents

Post, Richard F.

2016-02-23

An electrostatic (ES) device is described with electrodes that improve its performance metrics. Devices include ES generators and ES motors, which are comprised of one or more stators (stationary members) and one or more rotors (rotatable members). The stator and rotors are configured as a pair of concentric cylindrical structures and aligned about a common axis. The stator and rotor are comprised of an ensemble of discrete, longitudinal electrodes, which are axially oriented in an annular arrangement. The shape of the electrodes described herein enables the ES device to function at voltages significantly greater than that of the existing art, resulting in devices with greater power-handling capability and overall efficiency. Electrode shapes include, but are not limited to, rods, corrugated sheets and emulations thereof.

[Acute myocardial infarction after wasp sting without anaphylactic reaction].

PubMed

Bongo, Angelo Sante; Fornaro, Gianluigi; Sansa, Mara; Macciò, Sergio; Rognoni, Andrea

2005-03-01

Bites of hymenopterans (bees, wasps and hornets) are very frequent phenomena that can stir up allergical reactions in venom-susceptible patients but that seldom provoke acute myocardial infarction. In the literature we can find case reports of myocardial infarction after bites of hymenopterans, and preceded by an allergic reaction (sometimes with angiographic evidence of undamaged coronary arteries). The pathophysiological determinant seems to be related to the chemical composition of hymenopterans venom, basically made up by vasoactive and thrombogenic substances able to create vasospasm and coronary thrombosis. Our report refers to a 65-year-old male patient without prior cardiological and allergic events who, bitten by a sharm of three bees, complains of an acute large anterior myocardial infarction with angiographic evidence of thrombotic lesion of the proximal left anterior descending artery treated with direct stenting with procedural success, without showing allergical symptoms. The pathophysiological determinant seems to be related to the release of vasoactive amines and thrombogenic substances contained into the hymenopterans venom, the former able to produce vasospasm, the latter able to create diffuse thrombosis. The use of adrenaline itself to counteract the possible systemic allergic reaction appears to advise against the treatment of patients with cardiological symptoms or coronary artery disease and because of its strong vasoactive activity (it leads, in fact, to vasoconstriction) and thrombogenic effects.

Numerical emulation of Thru-Reflection-Line calibration for the de-embedding of Surface Acoustic Wave devices.

PubMed

Mencarelli, D; Djafari-Rouhani, B; Pennec, Y; Pitanti, A; Zanotto, S; Stocchi, M; Pierantoni, L

2018-06-18

In this contribution, a rigorous numerical calibration is proposed to characterize the excitation of propagating mechanical waves by interdigitated transducers (IDTs). The transition from IDT terminals to phonon waveguides is modeled by means of a general circuit representation that makes use of Scattering Matrix (SM) formalism. In particular, the three-step calibration approach called the Thru-Reflection-Line (TRL), that is a well-established technique in microwave engineering, has been successfully applied to emulate typical experimental conditions. The proposed procedure is suitable for the synthesis/optimization of surface-acoustic-wave (SAW) based devices: the TRL calibration allows to extract/de-embed the acoustic component, namely resonator or filter, from the outer IDT structure, regardless of complexity and size of the letter. We report, as a result, the hybrid scattering parameters of the IDT transition to a mechanical waveguide formed by a phononic crystal patterned on a piezoelectric AlN membrane, where the effect of a discontinuity from periodic to uniform mechanical waveguide is also characterized. In addition, to ensure the correctness of our numerical calculations, the proposed method has been validated by independent calculations.

A methodology to emulate and evaluate a productive virtual workstation

NASA Technical Reports Server (NTRS)

Krubsack, David; Haberman, David

1992-01-01

The Advanced Display and Computer Augmented Control (ADCACS) Program at ACT is sponsored by NASA Ames to investigate the broad field of technologies which must be combined to design a 'virtual' workstation for the Space Station Freedom. This program is progressing in several areas and resulted in the definition of requirements for a workstation. A unique combination of technologies at the ACT Laboratory have been networked to effectively create an experimental environment. This experimental environment allows the integration of nonconventional input devices with a high power graphics engine within the framework of an expert system shell which coordinates the heterogeneous inputs with the 'virtual' presentation. The flexibility of the workstation is evolved as experiments are designed and conducted to evaluate the condition descriptions and rule sets of the expert system shell and its effectiveness in driving the graphics engine. Workstation productivity has been defined by the achievable performance in the emulator of the calibrated 'sensitivity' of input devices, the graphics presentation, the possible optical enhancements to achieve a wide field of view color image and the flexibility of conditional descriptions in the expert system shell in adapting to prototype problems.

Quantitative assessment of four men using above-elbow prosthetic control.

PubMed

Popat, R A; Krebs, D E; Mansfield, J; Russell, D; Clancy, E; Gill-Body, K M; Hogan, N

1993-07-01

We studied the relationship between kinematically unconstrained activities of daily living (ADL) tasks and a kinematically constrained task in above-elbow (AE) amputee subjects using myoelectrically controlled prostheses. Four men, 24 to 49 years old, with unilateral AE amputation wore a prosthesis interfaced to a programmable controller to emulate two different elbow control schemes, conventional velocity and a new "natural" controller. Subjects were timed during three ADL tasks--cutting meat, donning socks, and rolling dough--with both controllers. The prosthesis emulator was then connected to a crank device with a handle, and the subjects turned the crank from bottom to top positions in a vertical plane using each controller. Synergistic shoulder-elbow joint coordination required for crank turning was quantified as the maximum slope of the change in elbow torque versus the change in crank-angle. Performance between the two controllers differed significantly for the crank test but not for ADL tasks. One subject did not complete all crank turning tests. Positive canonical correlation of 0.77 was found between time and crank domain measures. We conclude that biomechanical assessments should be integrated with time-based clinical tests to comprehensively evaluate performance of AE amputee subjects with a myoelectric device.

A Wireless Fully Passive Neural Recording Device for Unobtrusive Neuropotential Monitoring.

PubMed

Kiourti, Asimina; Lee, Cedric W L; Chae, Junseok; Volakis, John L

2016-01-01

We propose a novel wireless fully passive neural recording device for unobtrusive neuropotential monitoring. Previous work demonstrated the feasibility of monitoring emulated brain signals in a wireless fully passive manner. In this paper, we propose a novel realistic recorder that is significantly smaller and much more sensitive. The proposed recorder utilizes a highly efficient microwave backscattering method and operates without any formal power supply or regulating elements. Also, no intracranial wires or cables are required. In-vitro testing is performed inside a four-layer head phantom (skin, bone, gray matter, and white matter). Compared to our former implementation, the neural recorder proposed in this study has the following improved features: 1) 59% smaller footprint, 2) up to 20-dB improvement in neuropotential detection sensitivity, and 3) encapsulation in biocompatible polymer. For the first time, temporal emulated neuropotentials as low as 63 μVpp can be detected in a wireless fully passive manner. Remarkably, the high-sensitivity achieved in this study implies reading of most neural signals generated by the human brain. The proposed recorder brings forward transformational possibilities in wireless fully passive neural detection for a very wide range of applications (e.g., epilepsy, Alzheimer's, mental disorders, etc.).

Current status of nanotechnology approaches for cardiovascular disease: a personal perspective.

PubMed

Buxton, Denis B

2009-01-01

Nanotechnology is poised to have an increasing impact on cardiovascular health in coming years. Diagnostically, multiplexed point-of-care devices will enable rapid genotyping and biomarker measurement to optimize and tailor therapies for the individual patient. Nanoparticle-based molecular imaging agents will take advantage of targeted agents to provide increased insight into disease pathways rather then simply providing structural and functional information. Drug delivery will be impacted by targeting of nanoparticle-encapsulated drugs to the site of action, increasing the effective concentration and decreasing systemic dosage and side effects. Controlled and tailored release of drugs from polymers will improve control of pharmacokinetics and bioavailability. The application of nanotechnology to tissue engineering will facilitate the fabrication of better tissue implants in vitro, and provide scaffolds to promote regeneration in vivo taking advantage of the body's own repair mechanisms. Medical devices will benefit from the development of nanostructured surfaces and coatings to provide better control of thrombogenicity and infection. Taken together, these new technologies have enormous potential for improving the diagnosis and treatment of cardiovascular diseases. (c) 2009 John Wiley & Sons, Inc.

Stents: Biomechanics, Biomaterials, and Insights from Computational Modeling.

PubMed

Karanasiou, Georgia S; Papafaklis, Michail I; Conway, Claire; Michalis, Lampros K; Tzafriri, Rami; Edelman, Elazer R; Fotiadis, Dimitrios I

2017-04-01

Coronary stents have revolutionized the treatment of coronary artery disease. Improvement in clinical outcomes requires detailed evaluation of the performance of stent biomechanics and the effectiveness as well as safety of biomaterials aiming at optimization of endovascular devices. Stents need to harmonize the hemodynamic environment and promote beneficial vessel healing processes with decreased thrombogenicity. Stent design variables and expansion properties are critical for vessel scaffolding. Drug-elution from stents, can help inhibit in-stent restenosis, but adds further complexity as drug release kinetics and coating formulations can dominate tissue responses. Biodegradable and bioabsorbable stents go one step further providing complete absorption over time governed by corrosion and erosion mechanisms. The advances in computing power and computational methods have enabled the application of numerical simulations and the in silico evaluation of the performance of stent devices made up of complex alloys and bioerodible materials in a range of dimensions and designs and with the capacity to retain and elute bioactive agents. This review presents the current knowledge on stent biomechanics, stent fatigue as well as drug release and mechanisms governing biodegradability focusing on the insights from computational modeling approaches.

Thromboresistance Characterization of Extruded Nitric Oxide-Releasing Silicone Catheters

PubMed Central

Amoako, Kagya A.; Archangeli, Christopher; Handa, Hitesh; Major, Terry; Meyerhoff, Mark E.; Annich, Gail M.; Bartlett, Robert H.

2013-01-01

Intravascular catheters used in clinical practice can activate platelets, leading to thrombus formation and stagnation of blood flow. Nitric oxide (NO)-releasing polymers have been shown previously to reduce clot formation on a number of blood contacting devices. In this work, trilaminar NO-releasing silicone catheters were fabricated and tested for their thrombogenicity. All catheters had specifications of L = 6 cm, inner diameter = 21 gauge (0.0723 cm), outer diameter = 12 gauge (0.2052 cm), and NO-releasing layer thickness = 200 ± 11 μm. Control and NO-releasing catheters were characterized in vitro for their NO flux and NO release duration by gas phase chemiluminescence measurements. The catheters were then implanted in the right and left internal jugular veins of (N = 6 and average weight = 3 kg) adult male rabbits for 4 hours thrombogenicity testing. Platelet counts and function, methemoglobin (metHb), hemoglobin (Hb), and white cell counts and functional time (defined as patency time of catheter) were monitored as measured outcomes. Nitric oxide-releasing catheters (N = 6) maintained an average flux above (2 ± 0.5) × 10−10 mol/min/cm2 for more than 24 hours, whereas controls showed no NO release. Methemoglobin, Hb, white cell, and platelet counts and platelet function at 4 hours were not significantly different from baseline (α = 0.05). However, clots on controls were visibly larger and prevented blood draws at a significantly (p < 0.05) earlier time (2.3 ± 0.7 hours) into the experiment, whereas all NO-releasing catheters survived the entire 4 hours test period. Results indicate that catheter NO flux levels attenuated thrombus formation in a short-term animal model. PMID:22395119

Self-expanding nanoplatinum-coated nitinol devices for atrial septal defect and patent ductus arteriosus closure: a swine model.

PubMed

Lertsapcharoen, Pornthep; Khongphatthanayothin, Apichai; La-orkhun, Vidhavas; Supachokchaiwattana, Pentip; Charoonrut, Phingphol

2006-01-01

Our purpose was to evaluate self-expanding nanoplatinum-coated nitinol devices for transcatheter closure of atrial septal defects and patent ductus arteriosus in a swine model. The devices were braided from platinum-activated nitinol wires and filled with polyester to enhance thrombogenicity. The platinum activation of the nitinol wires was carried out with the help of Nanofusion technology. The coating of platinum covers the exposed surface of the nitinol wires and prevents the release of nickel into the blood stream after the implantation of the device but does not affect its shape memory, which makes the device self-expanding after it is loaded from the catheter. Atrial septal defects were created in 12 piglets by balloon dilation of the patent foramen ovale. The size of the device was selected on the basis of the diameter of the balloon and the size of the defect, measured by transthoracic echocardiography. The devices were successfully deployed in all 12 piglets under fluoroscopic study. Transthoracic color Doppler echocardiograms showed complete closure of the atrial septal defect within 15 minutes of device implantation. Twelve patent ductus arteriosus closure devices were deployed in the right or left subclavian arteries in 10 piglets. Angiograms showed complete occlusion of the subclavian arteries within a few minutes of device deployment. In the atrial septal defect cases, the autopsy findings showed complete organizing fibrin thrombus formation and complete neo-endothelialization on the outer surface of the devices within one week and six weeks of implantation, respectively. The use of self-expanding nanoplatinum-coated nitinol devices for the transcatheter closure of atrial septal defects and patent ductus arteriosus is feasible. The excellent occlusion result and complete neo-endothelialization of the devices in the swine model is an indication of the potential of these devices in human application.

Fractal-based wideband invisibility cloak

NASA Astrophysics Data System (ADS)

Cohen, Nathan; Okoro, Obinna; Earle, Dan; Salkind, Phil; Unger, Barry; Yen, Sean; McHugh, Daniel; Polterzycki, Stefan; Shelman-Cohen, A. J.

2015-03-01

A wideband invisibility cloak (IC) at microwave frequencies is described. Using fractal resonators in closely spaced (sub wavelength) arrays as a minimal number of cylindrical layers (rings), the IC demonstrates that it is physically possible to attain a `see through' cloaking device with: (a) wideband coverage; (b) simple and attainable fabrication; (c) high fidelity emulation of the free path; (d) minimal side scattering; (d) a near absence of shadowing in the scattering. Although not a practical device, this fractal-enabled technology demonstrator opens up new opportunities for diverted-image (DI) technology and use of fractals in wideband optical, infrared, and microwave applications.

SURGNET: An Integrated Surgical Data Transmission System for Telesurgery.

PubMed

Natarajan, Sriram; Ganz, Aura

2009-01-01

Remote surgery information requires quick and reliable transmission between the surgeon and the patient site. However, the networks that interconnect the surgeon and patient sites are usually time varying and lossy which can cause packet loss and delay jitter. In this paper we propose SURGNET, a telesurgery system for which we developed the architecture, algorithms and implemented it on a testbed. The algorithms include adaptive packet prediction and buffer time adjustment techniques which reduce the negative effects caused by the lossy and time varying networks. To evaluate the proposed SURGNET system, at the therapist site, we implemented a therapist panel which controls the force feedback device movements and provides image analysis functionality. At the patient site we controlled a virtual reality applet built in Matlab. The varying network conditions were emulated using NISTNet emulator. Our results show that even for severe packet loss and variable delay jitter, the proposed integrated synchronization techniques significantly improve SURGNET performance.

Characterization and Modeling of Nonfilamentary Ta/TaOx/TiO2/Ti Analog Synaptic Device

PubMed Central

Wang, Yu-Fen; Lin, Yen-Chuan; Wang, I-Ting; Lin, Tzu-Ping; Hou, Tuo-Hung

2015-01-01

A two-terminal analog synaptic device that precisely emulates biological synaptic features is expected to be a critical component for future hardware-based neuromorphic computing. Typical synaptic devices based on filamentary resistive switching face severe limitations on the implementation of concurrent inhibitory and excitatory synapses with low conductance and state fluctuation. For overcoming these limitations, we propose a Ta/TaOx/TiO2/Ti device with superior analog synaptic features. A physical simulation based on the homogeneous (nonfilamentary) barrier modulation induced by oxygen ion migration accurately reproduces various DC and AC evolutions of synaptic states, including the spike-timing-dependent plasticity and paired-pulse facilitation. Furthermore, a physics-based compact model for facilitating circuit-level design is proposed on the basis of the general definition of memristor devices. This comprehensive experimental and theoretical study of the promising electronic synapse can facilitate realizing large-scale neuromorphic systems. PMID:25955658

Packaging of electro-microfluidic devices

DOEpatents

Benavides, Gilbert L.; Galambos, Paul C.; Emerson, John A.; Peterson, Kenneth A.; Giunta, Rachel K.; Zamora, David Lee; Watson, Robert D.

2003-04-15

A new architecture for packaging surface micromachined electro-microfluidic devices is presented. This architecture relies on two scales of packaging to bring fluid to the device scale (picoliters) from the macro-scale (microliters). The architecture emulates and utilizes electronics packaging technology. The larger package consists of a circuit board with embedded fluidic channels and standard fluidic connectors (e.g. Fluidic Printed Wiring Board). The embedded channels connect to the smaller package, an Electro-Microfluidic Dual-Inline-Package (EMDIP) that takes fluid to the microfluidic integrated circuit (MIC). The fluidic connection is made to the back of the MIC through Bosch-etched holes that take fluid to surface micromachined channels on the front of the MIC. Electrical connection is made to bond pads on the front of the MIC.

Packaging of electro-microfluidic devices

DOEpatents

Benavides, Gilbert L.; Galambos, Paul C.; Emerson, John A.; Peterson, Kenneth A.; Giunta, Rachel K.; Watson, Robert D.

2002-01-01

A new architecture for packaging surface micromachined electro-microfluidic devices is presented. This architecture relies on two scales of packaging to bring fluid to the device scale (picoliters) from the macro-scale (microliters). The architecture emulates and utilizes electronics packaging technology. The larger package consists of a circuit board with embedded fluidic channels and standard fluidic connectors (e.g. Fluidic Printed Wiring Board). The embedded channels connect to the smaller package, an Electro-Microfluidic Dual-Inline-Package (EMDIP) that takes fluid to the microfluidic integrated circuit (MIC). The fluidic connection is made to the back of the MIC through Bosch-etched holes that take fluid to surface micromachined channels on the front of the MIC. Electrical connection is made to bond pads on the front of the MIC.

Visualization and Analysis of Biomaterial-Centered Thrombus Formation within a Defined Crevice Under Flow

PubMed Central

Jamiolkowski, Megan A.; Pedersen, Drake D.; Wu, Wei-Tao; Antaki, James F.; Wagner, William R.

2016-01-01

The blood flow pathway within a device, together with the biomaterial surfaces and status of the patient’s blood, are well-recognized factors in the development of thrombotic deposition and subsequent embolization. Blood flow patterns are of particular concern for devices such as blood pumps (i.e. ventricular assist devices, VADs) where shearing forces can be high, volumes are relatively large, and the flow fields can be complex. However, few studies have examined the effect of geometric irregularities on thrombus formation on clinically relevant opaque materials under flow. The objective of this study was to quantify human platelet deposition onto Ti6Al4V alloys, as well as positive and negative control surfaces, in the region of defined crevices (~50–150 µm in width) that might be encountered in many VADs or other cardiovascular devices. To achieve this, reconstituted fresh human blood with hemoglobin-depleted red blood cells (to achieve optical clarity while maintaining relevant rheology), long working optics, and a custom designed parallel plate flow chamber were employed. The results showed that the least amount of platelet deposition occurred in the largest crevice size examined, which was counterintuitive. The greatest levels of deposition occurred in the 90 µm and 53 µm crevices at the lower wall shear rate. The results suggest that while crevices may be unavoidable in device manufacturing, the crevice size might be tailored, depending on the flow conditions, to reduce the risk of thromboembolic events. Further, these data might be used to improve the accuracy of predictive models of thrombotic deposition in cardiovascular devices to help optimize the blood flow path and reduce device thrombogenicity. PMID:27156141

Realistic Modeling of Wireless Network Environments

DTIC Science & Technology

2015-03-01

wireless environment, namely vehicular networks. We also made a number of improvements to an emulation-based wireless testbed to improve channel model...and the two wireless devices used in the experiment (bottom). This testbed was used for point-point vehicular wireless experiments that used the...DSRC-based vehicular networks (~5.9 GHz). We were able to meet that goal, as described below. Figure 3: DSP Card 3.3 System design and

A low cost amplifier and acquisition system for cortical-electroncephalography in non-human applications.

PubMed

Viggiano, A; Coppola, G

2014-04-01

A simple circuit is described to make an AC-amplifier and an analog-to-digital converter in a single, compact solution, for use in basic research, but not on humans. The circuit sends data to and is powered from a common USB port of modern computers; using proper firmware and driver the communication with the device is an emulated RS232 serial port.

A Low Cost Amplifier and Acquisition System for Cortical-Electroncephalography in Non-Human Applications

PubMed Central

Viggiano, A; Coppola, G

2014-01-01

A simple circuit is described to make an AC-amplifier and an analog-to-digital converter in a single, compact solution, for use in basic research, but not on humans. The circuit sends data to and is powered from a common USB port of modern computers; using proper firmware and driver the communication with the device is an emulated RS232 serial port. PMID:24809030

Final Progress Report: Isotope Identification Algorithm for Rapid and Accurate Determination of Radioisotopes Feasibility Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rawool-Sullivan, Mohini; Bounds, John Alan; Brumby, Steven P.

2012-04-30

This is the final report of the project titled, 'Isotope Identification Algorithm for Rapid and Accurate Determination of Radioisotopes,' PMIS project number LA10-HUMANID-PD03. The goal of the work was to demonstrate principles of emulating a human analysis approach towards the data collected using radiation isotope identification devices (RIIDs). It summarizes work performed over the FY10 time period. The goal of the work was to demonstrate principles of emulating a human analysis approach towards the data collected using radiation isotope identification devices (RIIDs). Human analysts begin analyzing a spectrum based on features in the spectrum - lines and shapes that aremore » present in a given spectrum. The proposed work was to carry out a feasibility study that will pick out all gamma ray peaks and other features such as Compton edges, bremsstrahlung, presence/absence of shielding and presence of neutrons and escape peaks. Ultimately success of this feasibility study will allow us to collectively explain identified features and form a realistic scenario that produced a given spectrum in the future. We wanted to develop and demonstrate machine learning algorithms that will qualitatively enhance the automated identification capabilities of portable radiological sensors that are currently being used in the field.« less

Artificial Synaptic Devices Based on Natural Chicken Albumen Coupled Electric-Double-Layer Transistors

NASA Astrophysics Data System (ADS)

Wu, Guodong; Feng, Ping; Wan, Xiang; Zhu, Liqiang; Shi, Yi; Wan, Qing

2016-03-01

Recent progress in using biomaterials to fabricate functional electronics has got growing attention for the new generation of environmentally friendly and biocompatible electronic devices. As a kind of biological material with rich source, proteins are essential natural component of all organisms. At the same time, artificial synaptic devices are of great significance for neuromorphic systems because they can emulate the signal process and memory behaviors of biological synapses. In this report, natural chicken albumen with high proton conductivity was used as the coupling electrolyte film for organic/inorganic hybrid synaptic devices fabrication. Some important synaptic functions including paired-pulse facilitation, dynamic filtering, short-term to long-term memory transition and spatial summation and shunting inhibition were successfully mimicked. Our results are very interesting for biological friendly artificial neuron networks and neuromorphic systems.

Energy consumption analysis for various memristive networks under different learning strategies

NASA Astrophysics Data System (ADS)

Deng, Lei; Wang, Dong; Zhang, Ziyang; Tang, Pei; Li, Guoqi; Pei, Jing

2016-02-01

Recently, various memristive systems emerge to emulate the efficient computing paradigm of the brain cortex; whereas, how to make them energy efficient still remains unclear, especially from an overall perspective. Here, a systematical and bottom-up energy consumption analysis is demonstrated, including the memristor device level and the network learning level. We propose an energy estimating methodology when modulating the memristive synapses, which is simulated in three typical neural networks with different synaptic structures and learning strategies for both offline and online learning. These results provide an in-depth insight to create energy efficient brain-inspired neuromorphic devices in the future.

Bio-mimicked atomic-layer-deposited iron oxide-based memristor with synaptic potentiation and depression functions

NASA Astrophysics Data System (ADS)

Wan, Xiang; Gao, Fei; Lian, Xiaojuan; Ji, Xincun; Hu, Ertao; He, Lin; Tong, Yi; Guo, Yufeng

2018-06-01

In this study, an iron oxide (FeO x )-based memristor was investigated for the realization of artificial synapses. An FeO x resistive switching layer was prepared by self-limiting atomic layer deposition (ALD). The movement of oxygen vacancies enabled the device to have history-dependent synaptic functions, which was further demonstrated by device modeling and simulation. Analog synaptic potentiation/depression in conductance was emulated by applying consecutive voltage pulses in the simulation. Our results suggest that the ALD FeO x -based memristor can be used as the basic building block for neural networks, neuromorphic systems, and brain-inspired computers.

Design, development, and first in vivo results of an implantable ventricular assist device, MicroVad.

PubMed

Kerkhoffs, Wolfgang; Schumacher, Oliver; Meyns, Bart; Verbeken, Erik; Leunens, Veerle; Bollen, Hilde; Reul, Helmut

2004-10-01

The design concept and first in vitro and in vivo results of a long-term implantable ventricular assist device system based on a microaxial blood pump are presented. The blood-immersed parts of the pump consist of a single-stage impeller and a proximally integrated microelectric motor. Both parts are surrounded by a pump housing currently made of polycarbonate to allow visible access to the blood-exposed parts. A titanium inflow cage attached to the tip of the housing is directly implanted into the left ventricular apex. The outflow of the pump is connected to the descending aorta by means of an e-PTFE graft. The overall dimensions of the device are 12 mm in outer diameter and about 50 mm in length. The calculated lifetime of the device is up to 2 years. The system underwent long-term durability tests, hydraulic performance tests, dynamic stability tests, and in vitro hemolysis and thrombogenicity tests. Furthermore, animal tests have been performed in adult Dorset sheep. In a first series, the pump has been placed extracorporeally; in a second series, the pump was completely implanted. Mean duration of the animal experiments of the second series was 31 days (range 8-110 days, n=14); no anticoagulation was administered over the whole test period. Blood data revealed no significant changes in blood cell counts, ionogram, or any other value. No end-organ dysfunction induced by long-term support could be observed, nor did the pathology reveal any evidence of thromboembolic complications.

Nanowell-Trapped Charged Ligand-Bearing Nanoparticle Surfaces – A Novel Method of Enhancing Flow-Resistant Cell Adhesion

PubMed Central

Tran, Phat L.; Gamboa, Jessica R.; McCracken, Katherine E.; Riley, Mark R.

2014-01-01

Assuring cell adhesion to an underlying biomaterial surface is vital in implant device design and tissue engineering, particularly under circumstances where cells are subjected to potential detachment from overriding fluid flow. Cell-substrate adhesion is a highly regulated process involving the interplay of mechanical properties, surface topographic features, electrostatic charge, and biochemical mechanisms. At the nanoscale level the physical properties of the underlying substrate are of particular importance in cell adhesion. Conventionally, natural, pro-adhesive, and often thrombogenic, protein biomaterials are frequently utilized to facilitate adhesion. In the present study nanofabrication techniques are utilized to enhance the biological functionality of a synthetic polymer surface, polymethymethacrylate, with respect to cell adhesion. Specifically we examine the effect on cell adhesion of combining: 1. optimized surface texturing, 2. electrostatic charge and 3. cell adhesive ligands, uniquely assembled on the substrata surface, as an ensemble of nanoparticles trapped in nanowells. Our results reveal that the ensemble strategy leads to enhanced, more than simply additive, endothelial cell adhesion under both static and flow conditions. This strategy may be of particular utility for enhancing flow-resistant endothelialization of blood-contacting surfaces of cardiovascular devices subjected to flow-mediated shear. PMID:23225491

[Antiphospholipid syndrome: pathophysiology and clinicobiological aspects].

PubMed

Ksouri, H; Mellouli, F; Béjaoui, M

2008-01-01

Due to its heterogeneity and pathogenesis diversity, antiphospholipid syndrom remains a challenge for researchers more than a century after first antibody, the anticardiolipin antibody for syphilis diagnosis was discovered. After a review of the etiology and epitopic specificities of antiphospholipid antibodies, we propose a detailed overview of mechanisms and clinical aspects of antiphospholipid syndrome. We emphasize on the role of innate immunity and the involvement of endothelial cells Toll like receptors in the transduction signal of anti-beta2-glycoprotein I antibodies fixation, which induce a thrombogenic state. The thrombogenic role of the anti-beta2GPI antibodies direct against beta2GPI domain I in the clinical onset of this syndrome is also evoked. Diagnosis problems and clinicobiological manifestations in the light of the last international consensus statement of the classification criteria for antiphospholipid syndrome end this review.

A universal ankle-foot prosthesis emulator for human locomotion experiments.

PubMed

Caputo, Joshua M; Collins, Steven H

2014-03-01

Robotic prostheses have the potential to significantly improve mobility for people with lower-limb amputation. Humans exhibit complex responses to mechanical interactions with these devices, however, and computational models are not yet able to predict such responses meaningfully. Experiments therefore play a critical role in development, but have been limited by the use of product-like prototypes, each requiring years of development and specialized for a narrow range of functions. Here we describe a robotic ankle-foot prosthesis system that enables rapid exploration of a wide range of dynamical behaviors in experiments with human subjects. This emulator comprises powerful off-board motor and control hardware, a flexible Bowden cable tether, and a lightweight instrumented prosthesis, resulting in a combination of low mass worn by the human (0.96 kg) and high mechatronic performance compared to prior platforms. Benchtop tests demonstrated closed-loop torque bandwidth of 17 Hz, peak torque of 175 Nm, and peak power of 1.0 kW. Tests with an anthropomorphic pendulum "leg" demonstrated low interference from the tether, less than 1 Nm about the hip. This combination of low worn mass, high bandwidth, high torque, and unrestricted movement makes the platform exceptionally versatile. To demonstrate suitability for human experiments, we performed preliminary tests in which a subject with unilateral transtibial amputation walked on a treadmill at 1.25 ms-1 while the prosthesis behaved in various ways. These tests revealed low torque tracking error (RMS error of 2.8 Nm) and the capacity to systematically vary work production or absorption across a broad range (from -5 to 21 J per step). These results support the use of robotic emulators during early stage assessment of proposed device functionalities and for scientific study of fundamental aspects of human-robot interaction. The design of simple, alternate end-effectors would enable studies at other joints or with additional degrees of freedom.

Connecting the Brain to Itself through an Emulation

PubMed Central

Serruya, Mijail D.

2017-01-01

Pilot clinical trials of human patients implanted with devices that can chronically record and stimulate ensembles of hundreds to thousands of individual neurons offer the possibility of expanding the substrate of cognition. Parallel trains of firing rate activity can be delivered in real-time to an array of intermediate external modules that in turn can trigger parallel trains of stimulation back into the brain. These modules may be built in software, VLSI firmware, or biological tissue as in vitro culture preparations or in vivo ectopic construct organoids. Arrays of modules can be constructed as early stage whole brain emulators, following canonical intra- and inter-regional circuits. By using machine learning algorithms and classic tasks known to activate quasi-orthogonal functional connectivity patterns, bedside testing can rapidly identify ensemble tuning properties and in turn cycle through a sequence of external module architectures to explore which can causatively alter perception and behavior. Whole brain emulation both (1) serves to augment human neural function, compensating for disease and injury as an auxiliary parallel system, and (2) has its independent operation bootstrapped by a human-in-the-loop to identify optimal micro- and macro-architectures, update synaptic weights, and entrain behaviors. In this manner, closed-loop brain-computer interface pilot clinical trials can advance strong artificial intelligence development and forge new therapies to restore independence in children and adults with neurological conditions. PMID:28713235

USAF Expeditionary Security Operations 2040:A Technology Vision For Deployed Air Base Defense Capabilities

DTIC Science & Technology

2014-04-09

development is the ability to connect to language translation service providers, exemplified by the hand-held Enabling Language Service Anywhere ( ELSA ...device. Designed primarily for use by first responders, ELSA connects via cellular signal to a company employing interpreters for over 180 languages...69 ELSA provides a possible model for military emulation where a pool of linguists is available on-call for use in a tactical environment

Epitaxial Hexagonal Ferrites for Millimeter Wave Tunable Filters.

DTIC Science & Technology

1982-12-13

form of thin films or slabs, the LPE format should be particularly suitable. Another potential advantage of the LPE format is that the insulating...flux (solvent). In effect, this emulates the successful LPE garnet (YIG) technology which employs this flux. In contrast to garnets , Pb atoms can be...member for a workshop entitled "Application of Garnet and Ferrite Thin Films to Microwave Devices." The principal investigator also attended the 6th

Method Of Packaging And Assembling Electro-Microfluidic Devices

DOEpatents

Benavides, Gilbert L.; Galambos, Paul C.; Emerson, John A.; Peterson, Kenneth A.; Giunta, Rachel K.; Zamora, David Lee; Watson, Robert D.

2004-11-23

A new architecture for packaging surface micromachined electro-microfluidic devices is presented. This architecture relies on two scales of packaging to bring fluid to the device scale (picoliters) from the macro-scale (microliters). The architecture emulates and utilizes electronics packaging technology. The larger package consists of a circuit board with embedded fluidic channels and standard fluidic connectors (e.g. Fluidic Printed Wiring Board). The embedded channels connect to the smaller package, an Electro-Microfluidic Dual-Inline-Package (EMDIP) that takes fluid to the microfluidic integrated circuit (MIC). The fluidic connection is made to the back of the MIC through Bosch-etched holes that take fluid to surface micromachined channels on the front of the MIC. Electrical connection is made to bond pads on the front of the MIC.

Using quantum process tomography to characterize decoherence in an analog electronic device

NASA Astrophysics Data System (ADS)

Ostrove, Corey; La Cour, Brian; Lanham, Andrew; Ott, Granville

The mathematical structure of a universal gate-based quantum computer can be emulated faithfully on a classical electronic device using analog signals to represent a multi-qubit state. We describe a prototype device capable of performing a programmable sequence of single-qubit and controlled two-qubit gate operations on a pair of voltage signals representing the real and imaginary parts of a two-qubit quantum state. Analog filters and true-RMS voltage measurements are used to perform unitary and measurement gate operations. We characterize the degradation of the represented quantum state with successive gate operations by formally performing quantum process tomography to estimate the equivalent decoherence channel. Experimental measurements indicate that the performance of the device may be accurately modeled as an equivalent quantum operation closely resembling a depolarizing channel with a fidelity of over 99%. This work was supported by the Office of Naval Research under Grant No. N00014-14-1-0323.

Development of a Converter-Based Transmission Line Emulator with Three-Phase Short-Circuit Fault Emulation Capability

DOE PAGES

Zhang, Shuoting; Liu, Bo; Zheng, Sheng; ...

2018-01-01

A transmission line emulator has been developed to flexibly represent interconnected ac lines under normal operating conditions in a voltage source converter (VSC)-based power system emulation platform. As the most serious short-circuit fault condition, the three-phase short-circuit fault emulation is essential for power system studies. Here, this paper proposes a model to realize a three-phase short-circuit fault emulation at different locations along a single transmission line or one of several parallel-connected transmission lines. At the same time, a combination method is proposed to eliminate the undesired transients caused by the current reference step changes while switching between the fault statemore » and the normal state. Experiment results verify the developed transmission line three-phase short-circuit fault emulation capability.« less

Development of a Converter-Based Transmission Line Emulator with Three-Phase Short-Circuit Fault Emulation Capability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Shuoting; Liu, Bo; Zheng, Sheng

A transmission line emulator has been developed to flexibly represent interconnected ac lines under normal operating conditions in a voltage source converter (VSC)-based power system emulation platform. As the most serious short-circuit fault condition, the three-phase short-circuit fault emulation is essential for power system studies. Here, this paper proposes a model to realize a three-phase short-circuit fault emulation at different locations along a single transmission line or one of several parallel-connected transmission lines. At the same time, a combination method is proposed to eliminate the undesired transients caused by the current reference step changes while switching between the fault statemore » and the normal state. Experiment results verify the developed transmission line three-phase short-circuit fault emulation capability.« less

Is Brain Emulation Dangerous?

NASA Astrophysics Data System (ADS)

Eckersley, Peter; Sandberg, Anders

2013-12-01

Brain emulation is a hypothetical but extremely transformative technology which has a non-zero chance of appearing during the next century. This paper investigates whether such a technology would also have any predictable characteristics that give it a chance of being catastrophically dangerous, and whether there are any policy levers which might be used to make it safer. We conclude that the riskiness of brain emulation probably depends on the order of the preceding research trajectory. Broadly speaking, it appears safer for brain emulation to happen sooner, because slower CPUs would make the technology`s impact more gradual. It may also be safer if brains are scanned before they are fully understood from a neuroscience perspective, thereby increasing the initial population of emulations, although this prediction is weaker and more scenario-dependent. The risks posed by brain emulation also seem strongly connected to questions about the balance of power between attackers and defenders in computer security contests. If economic property rights in CPU cycles1 are essentially enforceable, emulation appears to be comparatively safe; if CPU cycles are ultimately easy to steal, the appearance of brain emulation is more likely to be a destabilizing development for human geopolitics. Furthermore, if the computers used to run emulations can be kept secure, then it appears that making brain emulation technologies ―open‖ would make them safer. If, however, computer insecurity is deep and unavoidable, openness may actually be more dangerous. We point to some arguments that suggest the former may be true, tentatively implying that it would be good policy to work towards brain emulation using open scientific methodology and free/open source software codebases

Guidance, Navigation and Control Digital Emulation Technology Laboratory. Volume 1. Part 2. Task 1: Digital Emulation Technology Laboratory

DTIC Science & Technology

1991-09-27

AD-A241 692 II I] II I11 ANNUAL REPORT VOLUME 1 PART 2 TASK 1: DIGITAL EMULATION TECHNOLOGY LABORATOIRY REPORT NO. AR-0142-91-001 September 27, 1991... DIGITAL EMULATION TECHNOLOGY LABORATORY Contract No. DASG60-89-C-0142 Sponsored By The United States Army ? trategic Defense Command COMPUTER...ANNUAL REPORT VOLUME 1 PART 2 TASK 1: DIGITAL EMULATION TECHNOLOGY LABORATORY September 27, 1991 Authors Thomas R. Collins and Stephen R. Wachtel

Lipoprotein(a): Biology and Clinical Importance

PubMed Central

McCormick, Sally P A

2004-01-01

Lipoprotein(a) [Lp(a)] is a unique lipoprotein that has emerged as an independent risk factor for developing vascular disease. Plasma Lp(a) levels above the common cut-off level of 300 mg/L place individuals at risk of developing heart disease particularly if combined with other lipid and thrombogenic risk factors. Studies in humans have shown Lp(a) levels to be hugely variable and under strict genetic control, largely by the apolipoprotein(a) [apo(a)] gene. In general, Lp(a) levels have proven difficult to manipulate, although some factors have been identified that can influence levels. Research has shown that Lp(a) has a high affinity for the arterial wall and displays many athero-thrombogenic properties. While a definite function for Lp(a) has not been identified, the last two decades of research have provided much information on the biology and clinical importance of Lp(a). PMID:18516206

MitoQ Loaded Chitosan-Hyaluronan Composite Membranes for Wound Healing

PubMed Central

Tamer, Tamer M.; Collins, Maurice N.; Valachová, Katarina; Hassan, Mohamed A.; Omer, Ahmed M.; Mohy-Eldin, Mohamed S.; Švík, Karol; Jurčík, Rastislav; Ondruška, Ľubomír; Biró, Csaba; Albadarin, Ahmad B.; Šoltés, Ladislav

2018-01-01

Two self-associating biopolymers, namely chitosan (Ch) and a high-molar-mass hyaluronan (HA), were used to prepare membranes with the aim to protect and to enhance the healing of injured skin. A mitochondrially-targeted antioxidant—MitoQ—was incorporated into the mixture of biopolymers prior to their self-association. These three-component membranes were evaluated in detail utilising surface roughness measurements, contact angle measurements, hemocompatibility, and thrombogenicity analyses. Furthermore, in vivo application of Ch/HA/MitoQ membranes was assessed on injured rabbit and rat skin utilizing histological methods. The results showed that the prepared thrombogenic Ch/HA/MitoQ membranes had higher roughness, which allowed for greater surface area for tissue membrane interaction during the healing processes, and lower cytotoxicity levels than controls. MitoQ-loaded composite membranes displayed superior healing properties in these animal models compared to control membranes. PMID:29642447

MitoQ Loaded Chitosan-Hyaluronan Composite Membranes for Wound Healing.

PubMed

Tamer, Tamer M; Collins, Maurice N; Valachová, Katarina; Hassan, Mohamed A; Omer, Ahmed M; Mohy-Eldin, Mohamed S; Švík, Karol; Jurčík, Rastislav; Ondruška, Ľubomír; Biró, Csaba; Albadarin, Ahmad B; Šoltés, Ladislav

2018-04-07

Two self-associating biopolymers, namely chitosan (Ch) and a high-molar-mass hyaluronan (HA), were used to prepare membranes with the aim to protect and to enhance the healing of injured skin. A mitochondrially-targeted antioxidant-MitoQ-was incorporated into the mixture of biopolymers prior to their self-association. These three-component membranes were evaluated in detail utilising surface roughness measurements, contact angle measurements, hemocompatibility, and thrombogenicity analyses. Furthermore, in vivo application of Ch/HA/MitoQ membranes was assessed on injured rabbit and rat skin utilizing histological methods. The results showed that the prepared thrombogenic Ch/HA/MitoQ membranes had higher roughness, which allowed for greater surface area for tissue membrane interaction during the healing processes, and lower cytotoxicity levels than controls. MitoQ-loaded composite membranes displayed superior healing properties in these animal models compared to control membranes.

Optimized pulsed write schemes improve linearity and write speed for low-power organic neuromorphic devices

NASA Astrophysics Data System (ADS)

Keene, Scott T.; Melianas, Armantas; Fuller, Elliot J.; van de Burgt, Yoeri; Talin, A. Alec; Salleo, Alberto

2018-06-01

Neuromorphic devices are becoming increasingly appealing as efficient emulators of neural networks used to model real world problems. However, no hardware to date has demonstrated the necessary high accuracy and energy efficiency gain over CMOS in both (1) training via backpropagation and (2) in read via vector matrix multiplication. Such shortcomings are due to device non-idealities, particularly asymmetric conductance tuning in response to uniform voltage pulse inputs. Here, by formulating a general circuit model for capacitive ion-exchange neuromorphic devices, we show that asymmetric nonlinearity in organic electrochemical neuromorphic devices (ENODes) can be suppressed by an appropriately chosen write scheme. Simulations based upon our model suggest that a nonlinear write-selector could reduce the switching voltage and energy, enabling analog tuning via a continuous set of resistance states (100 states) with extremely low switching energy (~170 fJ · µm‑2). This work clarifies the pathway to neural algorithm accelerators capable of parallelism during both read and write operations.

Estimation of Quasi-Stiffness of the Human Knee in the Stance Phase of Walking

PubMed Central

Shamaei, Kamran; Sawicki, Gregory S.; Dollar, Aaron M.

2013-01-01

Biomechanical data characterizing the quasi-stiffness of lower-limb joints during human locomotion is limited. Understanding joint stiffness is critical for evaluating gait function and designing devices such as prostheses and orthoses intended to emulate biological properties of human legs. The knee joint moment-angle relationship is approximately linear in the flexion and extension stages of stance, exhibiting nearly constant stiffnesses, known as the quasi-stiffnesses of each stage. Using a generalized inverse dynamics analysis approach, we identify the key independent variables needed to predict knee quasi-stiffness during walking, including gait speed, knee excursion, and subject height and weight. Then, based on the identified key variables, we used experimental walking data for 136 conditions (speeds of 0.75–2.63 m/s) across 14 subjects to obtain best fit linear regressions for a set of general models, which were further simplified for the optimal gait speed. We found R2 > 86% for the most general models of knee quasi-stiffnesses for the flexion and extension stages of stance. With only subject height and weight, we could predict knee quasi-stiffness for preferred walking speed with average error of 9% with only one outlier. These results provide a useful framework and foundation for selecting subject-specific stiffness for prosthetic and exoskeletal devices designed to emulate biological knee function during walking. PMID:23533662

Emulator-assisted data assimilation in complex models

NASA Astrophysics Data System (ADS)

Margvelashvili, Nugzar Yu; Herzfeld, Mike; Rizwi, Farhan; Mongin, Mathieu; Baird, Mark E.; Jones, Emlyn; Schaffelke, Britta; King, Edward; Schroeder, Thomas

2016-09-01

Emulators are surrogates of complex models that run orders of magnitude faster than the original model. The utility of emulators for the data assimilation into ocean models is still not well understood. High complexity of ocean models translates into high uncertainty of the corresponding emulators which may undermine the quality of the assimilation schemes based on such emulators. Numerical experiments with a chaotic Lorenz-95 model are conducted to illustrate this point and suggest a strategy to alleviate this problem through the localization of the emulation and data assimilation procedures. Insights gained through these experiments are used to design and implement data assimilation scenario for a 3D fine-resolution sediment transport model of the Great Barrier Reef (GBR), Australia.

Validation techniques for fault emulation of SRAM-based FPGAs

DOE PAGES

Quinn, Heather; Wirthlin, Michael

2015-08-07

A variety of fault emulation systems have been created to study the effect of single-event effects (SEEs) in static random access memory (SRAM) based field-programmable gate arrays (FPGAs). These systems are useful for augmenting radiation-hardness assurance (RHA) methodologies for verifying the effectiveness for mitigation techniques; understanding error signatures and failure modes in FPGAs; and failure rate estimation. For radiation effects researchers, it is important that these systems properly emulate how SEEs manifest in FPGAs. If the fault emulation systems does not mimic the radiation environment, the system will generate erroneous data and incorrect predictions of behavior of the FPGA inmore » a radiation environment. Validation determines whether the emulated faults are reasonable analogs to the radiation-induced faults. In this study we present methods for validating fault emulation systems and provide several examples of validated FPGA fault emulation systems.« less

Interplay of multiple synaptic plasticity features in filamentary memristive devices for neuromorphic computing

NASA Astrophysics Data System (ADS)

La Barbera, Selina; Vincent, Adrien F.; Vuillaume, Dominique; Querlioz, Damien; Alibart, Fabien

2016-12-01

Bio-inspired computing represents today a major challenge at different levels ranging from material science for the design of innovative devices and circuits to computer science for the understanding of the key features required for processing of natural data. In this paper, we propose a detail analysis of resistive switching dynamics in electrochemical metallization cells for synaptic plasticity implementation. We show how filament stability associated to joule effect during switching can be used to emulate key synaptic features such as short term to long term plasticity transition and spike timing dependent plasticity. Furthermore, an interplay between these different synaptic features is demonstrated for object motion detection in a spike-based neuromorphic circuit. System level simulation presents robust learning and promising synaptic operation paving the way to complex bio-inspired computing systems composed of innovative memory devices.

Emulation-Based Virtual Laboratories: A Low-Cost Alternative to Physical Experiments in Control Engineering Education

ERIC Educational Resources Information Center

Goodwin, G. C.; Medioli, A. M.; Sher, W.; Vlacic, L. B.; Welsh, J. S.

2011-01-01

This paper argues the case for emulation-based virtual laboratories in control engineering education. It demonstrates that such emulation experiments can give students an industrially relevant educational experience at relatively low cost. The paper also describes a particular emulation-based system that has been developed with the aim of giving…

Scalable and reusable emulator for evaluating the performance of SS7 networks

NASA Astrophysics Data System (ADS)

Lazar, Aurel A.; Tseng, Kent H.; Lim, Koon Seng; Choe, Winston

1994-04-01

A scalable and reusable emulator was designed and implemented for studying the behavior of SS7 networks. The emulator design was largely based on public domain software. It was developed on top of an environment supported by PVM, the Parallel Virtual Machine, and managed by OSIMIS-the OSI Management Information Service platform. The emulator runs on top of a commercially available ATM LAN interconnecting engineering workstations. As a case study for evaluating the emulator, the behavior of the Singapore National SS7 Network under fault and unbalanced loading conditions was investigated.

A Prolog Emulator

NASA Technical Reports Server (NTRS)

Tick, Evan

1987-01-01

This note describes an efficient software emulator for the Warren Abstract Machine (WAM) Prolog architecture. The version of the WAM implemented is called Lcode. The Lcode emulator, written in C, executes the 'naive reverse' benchmark at 3900 LIPS. The emulator is one of a set of tools used to measure the memory-referencing characteristics and performance of Prolog programs. These tools include a compiler, assembler, and memory simulators. An overview of the Lcode architecture is given here, followed by a description and listing of the emulator code implementing each Lcode instruction. This note will be of special interest to those studying the WAM and its performance characteristics. In general, this note will be of interest to those creating efficient software emulators for abstract machine architectures.

Mouse manipulation through single-switch scanning.

PubMed

Blackstien-Adler, Susie; Shein, Fraser; Quintal, Janet; Birch, Shae; Weiss, Patrice L Tamar

2004-01-01

Given the current extensive reliance on the graphical user interface, independent access to computer software requires that users be able to manipulate a pointing device of some type (e.g., mouse, trackball) or be able to emulate a mouse by some other means (e.g., scanning). The purpose of the present study was to identify one or more optimal single-switch scanning mouse emulation strategies. Four alternative scanning strategies (continuous Cartesian, discrete Cartesian, rotational, and hybrid quadrant/continuous Cartesian) were selected for testing based on current market availability as well as on theoretical considerations of their potential speed and accuracy. Each strategy was evaluated using a repeated measures study design by means of a test program that permitted mouse emulation via any one of four scanning strategies in a motivating environment; response speed and accuracy could be automatically recorded and considered in view of the motor, cognitive, and perceptual demands of each scanning strategy. Ten individuals whose disabilities required them to operate a computer via single-switch scanning participated in the study. Results indicated that Cartesian scanning was the preferred and most effective scanning strategy. There were no significant differences between results from the Continuous Cartesian and Discrete Cartesian scanning strategies. Rotational scanning was quite slow with respect to the other strategies, although it was equally accurate. Hybrid Quadrant scanning improved access time but at the cost of fewer correct selections. These results demonstrated the importance of testing and comparing alternate single-switch scanning strategies.

Evaluation of Electromechanical Systems Dynamically Emulating a Candidate Hydrokinetic Turbine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cavagnaro, Robert J.; Neely, Jason C.; Fay, Franois-Xavier

The use of controllable motor-generator sets to emulate the dynamics of a hydrokinetic turbine is evaluated as an alternative to field testing a prototype. The emulator control dynamic equations are presented, methods for scaling turbine parameters are examined, and experimental results are presented from three electromechanical emulation machines (EEMs) programmed to emulate the same vertical-axis fixed-pitch turbine. Although hardware platforms and control implementations varied, results show that each EEM is successful in emulating the turbine model, thus demonstrating the general feasibility of the approach. However, performance of motor control under torque command, current command or speed command differed. In onemore » of the EEMs evaluated, the power take off controller tracks the maximum power-point of the turbine in response to turbulence. Utilizing realistic inflow conditions and control laws, the emulator dynamic speed response is shown to agree well at low frequencies with numerical simulation but to deviate at high frequencies.« less

Evaluation of Electromechanical Systems Dynamically Emulating a Candidate Hydrokinetic Turbine

DOE PAGES

Cavagnaro, Robert J.; Neely, Jason C.; Fay, Franois-Xavier; ...

2016-11-06

The use of controllable motor-generator sets to emulate the dynamics of a hydrokinetic turbine is evaluated as an alternative to field testing a prototype. The emulator control dynamic equations are presented, methods for scaling turbine parameters are examined, and experimental results are presented from three electromechanical emulation machines (EEMs) programmed to emulate the same vertical-axis fixed-pitch turbine. Although hardware platforms and control implementations varied, results show that each EEM is successful in emulating the turbine model, thus demonstrating the general feasibility of the approach. However, performance of motor control under torque command, current command or speed command differed. In onemore » of the EEMs evaluated, the power take off controller tracks the maximum power-point of the turbine in response to turbulence. Utilizing realistic inflow conditions and control laws, the emulator dynamic speed response is shown to agree well at low frequencies with numerical simulation but to deviate at high frequencies.« less

A Clock Fingerprints-Based Approach for Wireless Transmitter Identification

NASA Astrophysics Data System (ADS)

Zhao, Caidan; Xie, Liang; Huang, Lianfen; Yao, Yan

Cognitive radio (CR) was proposed as one of the promising solutions for low spectrum utilization. However, security problems such as the primary user emulation (PUE) attack severely limit its applications. In this paper, we propose a clock fingerprints-based authentication approach to prevent PUE attacks in CR networks with the help of curve fitting and classifier. An experimental setup was constructed using the WLAN cards and software radio devices, and the corresponding results show that satisfied identification can be achieved for wireless transmitters.

Simulating interfering fringe displacements by lateral shifts of a camera for educational purposes

NASA Astrophysics Data System (ADS)

Rivera-Ortega, Uriel

2018-07-01

In this manuscript we propose a simple method to emulate fringe displacements in a fringe pattern, due to the interference of two plane waves, by using lateral shifts of a CMOS detector under the scheme of a Twyman–Green interferometric setup, avoiding unwanted vibrations and the need for specific and expensive devices in order to accomplish the task. The simplicity of the proposed experimental setup allows it to be easily replicated and used for teaching or demonstrative purposes, essentially for undergraduate students.

High density electronic circuit and process for making

DOEpatents

Morgan, William P.

1999-01-01

High density circuits with posts that protrude beyond one surface of a substrate to provide easy mounting of devices such as integrated circuits. The posts also provide stress relief to accommodate differential thermal expansion. The process allows high interconnect density with fewer alignment restrictions and less wasted circuit area than previous processes. The resulting substrates can be test platforms for die testing and for multi-chip module substrate testing. The test platform can contain active components and emulate realistic operational conditions, replacing shorts/opens net testing.

VASCULAR AND THROMBOGENIC EFFECTS OF PULMONARY EXPOSURE TO LIBBY AMPHIBOLE

EPA Science Inventory

Acute pulmonary injury and chronic disease can impact the systemic vasculature through the release of inflammogenic and vasoactive mediators from the lung into the circulation. Exposure to Libby amphibole (LA) asbestos is associated with increased human cardiovascular mortality a...

Revisiting the role of durable polymers in cardiovascular devices.

PubMed

Mori, Hiroyoshi; Otsuka, Fumiyuki; Gupta, Anuj; Jinnouchi, Hiroyuki; Torii, Sho; Harari, Emanuel; Virmani, Renu; Finn, Aloke V

2017-11-01

Polymers are an essential component of drug-eluting stents (DES) used to control drug release but remain the most controversial component of DES technology. There are two types of polymers employed in DES: durable polymer based DES (DP-DES) and biodegradable polymer DES (BP-DES). First-generation DES were exclusively composed of DP and demonstrated increased rates of late stent failure due in part to poor polymer biocompatibility. Newer generations DES use more biocompatible durable polymers or biodegradable polymers. Areas covered: We will cover issues identified with 1st-generation DP-DES, areas of success and failure in 2nd-generation DP-DES and examine the promise and shortcomings of BP-DES. Briefly, fluorinated polymers used in 2nd-generation DP-DES have excellent anti-thrombogenicity and better biocompatibility than 1st-generation DES polymers. However, these devices lead to persistent drug exposure to the endothelium which impairs endothelial function and predisposes towards neoatherosclerosis. Meanwhile, BP-DES has shortened the duration of drug exposure which might be beneficial for endothelial functional recovery leading to less neoatherosclerosis. However, it remains uncertain whether the long-term biocompatibility of bare metal surfaces is better than that of polymer-coated metals. Expert commentary: Each technology has distinct advantages, which can be optimized depending upon the particular characteristics of the patient being treated.

Influence of surgical implantation angle of left ventricular assist device outflow graft and management of aortic valve opening on the risk of stroke in heart failure patients

NASA Astrophysics Data System (ADS)

Chivukula, V. Keshav; McGah, Patrick; Prisco, Anthony; Beckman, Jennifer; Mokadam, Nanush; Mahr, Claudius; Aliseda, Alberto

2016-11-01

Flow in the aortic vasculature may impact stroke risk in patients with left ventricular assist devices (LVAD) due to severely altered hemodynamics. Patient-specific 3D models of the aortic arch and great vessels were created with an LVAD outflow graft at 45, 60 and 90° from centerline of the ascending aorta, in order to understand the effect of surgical placement on hemodynamics and thrombotic risk. Intermittent aortic valve opening (once every five cardiac cycles) was simulated and the impact of this residual native output investigated for the potential to wash out stagnant flow in the aortic root region. Unsteady CFD simulations with patient-specific boundary conditions were performed. Particle tracking for 10 cardiac cycles was used to determine platelet residence times and shear stress histories. Thrombosis risk was assessed by a combination of Eulerian and Lagrangian metrics and a newly developed thrombogenic potential metric. Results show a strong influence of LVAD outflow graft angle on hemodynamics in the ascending aorta and consequently on stroke risk, with a highly positive impact of aortic valve opening, even at low frequencies. Optimization of LVAD implantation and management strategies based on patient-specific simulations to minimize stroke risk will be presented

Multi-Constituent Simulation of Thrombus Deposition

NASA Astrophysics Data System (ADS)

Wu, Wei-Tao; Jamiolkowski, Megan A.; Wagner, William R.; Aubry, Nadine; Massoudi, Mehrdad; Antaki, James F.

2017-02-01

In this paper, we present a spatio-temporal mathematical model for simulating the formation and growth of a thrombus. Blood is treated as a multi-constituent mixture comprised of a linear fluid phase and a thrombus (solid) phase. The transport and reactions of 10 chemical and biological species are incorporated using a system of coupled convection-reaction-diffusion (CRD) equations to represent three processes in thrombus formation: initiation, propagation and stabilization. Computational fluid dynamic (CFD) simulations using the libraries of OpenFOAM were performed for two illustrative benchmark problems: in vivo thrombus growth in an injured blood vessel and in vitro thrombus deposition in micro-channels (1.5 mm × 1.6 mm × 0.1 mm) with small crevices (125 μm × 75 μm and 125 μm × 137 μm). For both problems, the simulated thrombus deposition agreed very well with experimental observations, both spatially and temporally. Based on the success with these two benchmark problems, which have very different flow conditions and biological environments, we believe that the current model will provide useful insight into the genesis of thrombosis in blood-wetted devices, and provide a tool for the design of less thrombogenic devices.

Selective inhibition by a synthetic hirudin peptide of fibrin-dependent thrombosis in baboons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cadroy, Y.; Hanson, S.R.; Harker, L.A.

1991-02-15

To determine the importance of the thrombin substrate recognition exosite for fibrinogen binding in the formation of both arterial and venous thrombi the authors evaluated the antithrombotic effects of the tyrosine-sulfated dodecapeptide from residues 53-64 of hirudin (H peptide) in a nonhuman primate model. This peptide was studied because it inhibits thrombin cleavages of fibrinogen by simple competition without blocking enzyme catalytic-site function. When an exteriorized arteriovenous access shunt model was used in baboons (Papio anubis), thrombus formation was induced by placing a thrombogenic device made of (i) a segment of tubing coated covalently with type I collagen, which generatedmore » platelet-rich thrombi under arterial flow conditions, and (ii) two subsequent annular regions of flow expansion that produced fibrin-rich thrombi typically associated with venous valves and veins. Thrombus formation was quantified by measurements of {sup 111}In-labeled platelet and {sup 125}I-labeled fibrinogen deposition in both arterial-flow and venous-flow portions of the device. These finding suggest that, by competitive inhibition of fibrinogen binding to thrombin, fibrin-rich venous-type thrombus formation may be selectively prevented. This strategy may be therapeutically attractive for preserving normal platelet function when conventional anticoagulant therapy is contraindicated.« less

Multi-Constituent Simulation of Thrombus Deposition

PubMed Central

Wu, Wei-Tao; Jamiolkowski, Megan A.; Wagner, William R.; Aubry, Nadine; Massoudi, Mehrdad; Antaki, James F.

2017-01-01

In this paper, we present a spatio-temporal mathematical model for simulating the formation and growth of a thrombus. Blood is treated as a multi-constituent mixture comprised of a linear fluid phase and a thrombus (solid) phase. The transport and reactions of 10 chemical and biological species are incorporated using a system of coupled convection-reaction-diffusion (CRD) equations to represent three processes in thrombus formation: initiation, propagation and stabilization. Computational fluid dynamic (CFD) simulations using the libraries of OpenFOAM were performed for two illustrative benchmark problems: in vivo thrombus growth in an injured blood vessel and in vitro thrombus deposition in micro-channels (1.5 mm × 1.6 mm × 0.1 mm) with small crevices (125 μm × 75 μm and 125 μm × 137 μm). For both problems, the simulated thrombus deposition agreed very well with experimental observations, both spatially and temporally. Based on the success with these two benchmark problems, which have very different flow conditions and biological environments, we believe that the current model will provide useful insight into the genesis of thrombosis in blood-wetted devices, and provide a tool for the design of less thrombogenic devices. PMID:28218279

Multi-Constituent Simulation of Thrombus Deposition.

PubMed

Wu, Wei-Tao; Jamiolkowski, Megan A; Wagner, William R; Aubry, Nadine; Massoudi, Mehrdad; Antaki, James F

2017-02-20

In this paper, we present a spatio-temporal mathematical model for simulating the formation and growth of a thrombus. Blood is treated as a multi-constituent mixture comprised of a linear fluid phase and a thrombus (solid) phase. The transport and reactions of 10 chemical and biological species are incorporated using a system of coupled convection-reaction-diffusion (CRD) equations to represent three processes in thrombus formation: initiation, propagation and stabilization. Computational fluid dynamic (CFD) simulations using the libraries of OpenFOAM were performed for two illustrative benchmark problems: in vivo thrombus growth in an injured blood vessel and in vitro thrombus deposition in micro-channels (1.5 mm × 1.6 mm × 0.1 mm) with small crevices (125 μm × 75 μm and 125 μm × 137 μm). For both problems, the simulated thrombus deposition agreed very well with experimental observations, both spatially and temporally. Based on the success with these two benchmark problems, which have very different flow conditions and biological environments, we believe that the current model will provide useful insight into the genesis of thrombosis in blood-wetted devices, and provide a tool for the design of less thrombogenic devices.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quinn, Heather; Wirthlin, Michael

A variety of fault emulation systems have been created to study the effect of single-event effects (SEEs) in static random access memory (SRAM) based field-programmable gate arrays (FPGAs). These systems are useful for augmenting radiation-hardness assurance (RHA) methodologies for verifying the effectiveness for mitigation techniques; understanding error signatures and failure modes in FPGAs; and failure rate estimation. For radiation effects researchers, it is important that these systems properly emulate how SEEs manifest in FPGAs. If the fault emulation systems does not mimic the radiation environment, the system will generate erroneous data and incorrect predictions of behavior of the FPGA inmore » a radiation environment. Validation determines whether the emulated faults are reasonable analogs to the radiation-induced faults. In this study we present methods for validating fault emulation systems and provide several examples of validated FPGA fault emulation systems.« less

Emulation as an Integrating Principle for Cognition

PubMed Central

Colder, Brian

2011-01-01

Emulations, defined as ongoing internal representations of potential actions and the futures those actions are expected to produce, play a critical role in directing human bodily activities. Studies of gross motor behavior, perception, allocation of attention, response to errors, interoception, and homeostatic activities, and higher cognitive reasoning suggest that the proper execution of all these functions relies on emulations. Further evidence supports the notion that reinforcement learning in humans is aimed at updating emulations, and that action selection occurs via the advancement of preferred emulations toward realization of their action and environmental prediction. Emulations are hypothesized to exist as distributed active networks of neurons in cortical and sub-cortical structures. This manuscript ties together previously unrelated theories of the role of prediction in different aspects of human information processing to create an integrated framework for cognition. PMID:21660288

Advanced technologies for cardiac valvular replacement, transcatheter innovations and reconstructive surgery.

PubMed

Jamieson, W R Eric

2006-01-01

Since the 2002 Surgical Technology International monograph on valvular prostheses, there have been significant developmental and investigative advances. Aortic bioprostheses and mechanical prostheses have undergone design changes to optimize hemodynamics and prevent patient-prosthesis mismatch to have a potential satisfactory influence on survival. There has been continual technological improvements striving to bring forward advances that improve the durability of bioprostheses and reduce the thrombogenicity of mechanical prostheses. There also has been a continuance to preserve biological tissue with glutaraldehyde, rather than clinically evaluate other cross-linking technologies, by controlling or retarding calcification with therapies to control phospholipids and residual aldehydes. The techniques of mitral valve reconstruction have now been well established and new annuloplasty rings have been designed for the potential of maintaining the anatomical and physiological characteristics of the mitral annulus. Several objectives exist for annuloplasty, namely remodeling of the length and shape of the dilated annulus, prevention of dilatation of the annulus, and support for the potentially fragile area after partial-leaflet resection. Currently, there exists an emergence of catheter-based therapies for management of aortic stenosis and mitral regurgitation. For management of selected populations with critical aortic stenosis, techniques for aortic valve substitution have been developed for both antegrade and retrograde catheter techniques, as well as apical transventricular implantation. Mitral regurgitation has been addressed by experimental transcoronary sinus, stent-like devices and transventricular, edge-to-edge leaflet devices. The devices, descriptions and pictorial images comprise this monograph.

Demonstration of emulator-based Bayesian calibration of safety analysis codes: Theory and formulation

DOE PAGES

Yurko, Joseph P.; Buongiorno, Jacopo; Youngblood, Robert

2015-05-28

System codes for simulation of safety performance of nuclear plants may contain parameters whose values are not known very accurately. New information from tests or operating experience is incorporated into safety codes by a process known as calibration, which reduces uncertainty in the output of the code and thereby improves its support for decision-making. The work reported here implements several improvements on classic calibration techniques afforded by modern analysis techniques. The key innovation has come from development of code surrogate model (or code emulator) construction and prediction algorithms. Use of a fast emulator makes the calibration processes used here withmore » Markov Chain Monte Carlo (MCMC) sampling feasible. This study uses Gaussian Process (GP) based emulators, which have been used previously to emulate computer codes in the nuclear field. The present work describes the formulation of an emulator that incorporates GPs into a factor analysis-type or pattern recognition-type model. This “function factorization” Gaussian Process (FFGP) model allows overcoming limitations present in standard GP emulators, thereby improving both accuracy and speed of the emulator-based calibration process. Calibration of a friction-factor example using a Method of Manufactured Solution is performed to illustrate key properties of the FFGP based process.« less

Real-time emulation of neural images in the outer retinal circuit.

PubMed

Hasegawa, Jun; Yagi, Tetsuya

2008-12-01

We describe a novel real-time system that emulates the architecture and functionality of the vertebrate retina. This system reconstructs the neural images formed by the retinal neurons in real time by using a combination of analog and digital systems consisting of a neuromorphic silicon retina chip, a field-programmable gate array, and a digital computer. While the silicon retina carries out the spatial filtering of input images instantaneously, using the embedded resistive networks that emulate the receptive field structure of the outer retinal neurons, the digital computer carries out the temporal filtering of the spatially filtered images to emulate the dynamical properties of the outer retinal circuits. The emulations of the neural image, including 128 x 128 bipolar cells, are carried out at a frame rate of 62.5 Hz. The emulation of the response to the Hermann grid and a spot of light and an annulus of lights has demonstrated that the system responds as expected by previous physiological and psychophysical observations. Furthermore, the emulated dynamics of neural images in response to natural scenes revealed the complex nature of retinal neuron activity. We have concluded that the system reflects the spatiotemporal responses of bipolar cells in the vertebrate retina. The proposed emulation system is expected to aid in understanding the visual computation in the retina and the brain.

Hardware and Software Integration to Support Real-Time Space Link Emulation

NASA Technical Reports Server (NTRS)

Murawski, Robert; Bhasin, Kul; Bittner, David; Sweet, Aaron; Coulter, Rachel; Schwab, Devin

2012-01-01

Prior to operational use, communications hardware and software must be thoroughly tested and verified. In space-link communications, field testing equipment can be prohibitively expensive and cannot test to non-ideal situations. In this paper, we show how software and hardware emulation tools can be used to accurately model the characteristics of a satellite communication channel in a lab environment. We describe some of the challenges associated with developing an emulation lab and present results to demonstrate the channel modeling. We then show how network emulation software can be used to extend a hardware emulation model without requiring additional network and channel simulation hardware.

Hardware and Software Integration to Support Real-Time Space-Link Emulation

NASA Technical Reports Server (NTRS)

Murawski, Robert; Bhasin, Kul; Bittner, David

2012-01-01

Prior to operational use, communications hardware and software must be thoroughly tested and verified. In space-link communications, field testing equipment can be prohibitively expensive and cannot test to non-ideal situations. In this paper, we show how software and hardware emulation tools can be used to accurately model the characteristics of a satellite communication channel in a lab environment. We describe some of the challenges associated with developing an emulation lab and present results to demonstrate the channel modeling. We then show how network emulation software can be used to extend a hardware emulation model without requiring additional network and channel simulation hardware.

Thrombogenicity and central pulse pressure to enhance prediction of ischemic event occurrence in patients with established coronary artery disease: The MAGMA-ischemia score.

PubMed

Bliden, Kevin P; Chaudhary, Rahul; Navarese, Eliano P; Sharma, Tushar; Kaza, Himabindu; Tantry, Udaya S; Gurbel, Paul A

2018-01-01

Conventional cardiovascular risk estimators based on clinical demographics have limited prediction of coronary events. Markers for thrombogenicity and vascular function have not been explored in risk estimation of high-risk patients with coronary artery disease. We aimed to develop a clinical and biomarker score to predict 3-year adverse cardiovascular events. Four hundred eleven patients, with ejection fraction ≥40% undergoing coronary angiography, and found to have a luminal diameter stenosis ≥50%, were included in the analysis. Thrombelastography indices and central pulse pressure (CPP) were determined at the time of catheterization. We identified predictors of death, myocardial infarction (MI) or stroke and developed a numerical ischemia risk score. The primary endpoint of cardiovascular death, MI or stroke occurred in 22 patients (5.4%). The factors associated with events were age, prior PCI or CABG, diabetes, CPP, and thrombin-induced platelet-fibrin clot strength, and were included in the MAGMA-ischemia score. The MAGMA-ischemia score showed a c-statistic of 0.85 (95% Confidence Interval [CI] 0.80-0.87; p<0.001) for the primary endpoint. In the subset of patients who underwent revascularization, the c-statistic was 0.90 (p<0.001). Patients with MAGMA-ischemia score greater than 5 had highest risk to develop clinical events, hazard ratio for the primary endpoint: 13.9 (95% CI 5.8-33.1, p<0.001) and for the secondary endpoint: 4.8 (95% CI 2.3-9.6, p<0.001). When compared to previous models, the MAGMA-ischemia score yielded a higher discrimination. Inclusion of CPP and assessment of thrombogenicity in a novel score for patients with documented CAD enhanced the prediction of events. Copyright © 2017 Elsevier B.V. All rights reserved.

Virgin olive oil, palm olein and coconut oil diets do not raise cell adhesion molecules and thrombogenicity indices in healthy Malaysian adults.

PubMed

Voon, P T; Ng, T K W; Lee, V K M; Nesaretnam, K

2015-06-01

Effects of high-protein diets that are rich in saturated fats on cell adhesion molecules, thrombogenicity and other nonlipid markers of atherosclerosis in humans have not been firmly established. We aim to investigate the effects of high-protein Malaysian diets prepared separately with virgin olive oil (OO), palm olein (PO) and coconut oil (CO) on cell adhesion molecules, lipid inflammatory mediators and thromobogenicity indices in healthy adults. A randomized cross-over intervention with three dietary sequences, using virgin OO, PO and CO as test fats, was carried out for 5 weeks on each group consisting of 45 men and women. These test fats were incorporated separately at two-thirds of 30% fat calories into high-protein Malaysian diets. For fasting and nonfasting blood samples, no significant differences were observed on the effects of the three test-fat diets on thrombaxane B2 (TXB2), TXB2/PGF1α ratios and soluble intracellular and vascular cell adhesion molecules. The OO diet induced significantly lower (P<0.05) plasma leukotriene B4 (LTB4) compared with the other two test diets, whereas PGF1α concentrations were significantly higher (P<0.05) at the end of the PO diet compared with the OO diet. Diets rich in saturated fatty acids from either PO or CO and high in monounsaturated oleic acid from virgin OO do not alter the thrombogenicity indices-cellular adhesion molecules, thromboxane B2 (TXB2) and TXB2/prostacyclin (PGF1α) ratios. However, the OO diet lowered plasma proinflammatory LTB4, whereas the PO diet raised the antiaggregatory plasma PGF1α in healthy Malaysian adults. This trial was registered at clinicaltrials.gov as NCT 00941837.

Three Realizations and Comparison of Hardware for Piezoresistive Tactile Sensors

PubMed Central

Vidal-Verdú, Fernando; Oballe-Peinado, Óscar; Sánchez-Durán, José A.; Castellanos-Ramos, Julián; Navas-González, Rafael

2011-01-01

Tactile sensors are basically arrays of force sensors that are intended to emulate the skin in applications such as assistive robotics. Local electronics are usually implemented to reduce errors and interference caused by long wires. Realizations based on standard microcontrollers, Programmable Systems on Chip (PSoCs) and Field Programmable Gate Arrays (FPGAs) have been proposed by the authors for the case of piezoresistive tactile sensors. The solution employing FPGAs is especially relevant since their performance is closer to that of Application Specific Integrated Circuits (ASICs) than that of the other devices. This paper presents an implementation of such an idea for a specific sensor. For the purpose of comparison, the circuitry based on the other devices is also made for the same sensor. This paper discusses the implementation issues, provides details regarding the design of the hardware based on the three devices and compares them. PMID:22163797

Powerful timing generator using mono-chip timers: An application to pulsed nuclear magnetic resonance

NASA Astrophysics Data System (ADS)

Saint-Jalmes, Hervé; Barjhoux, Yves

1982-01-01

We present a 10 line-7 MHz timing generator built on a single board around two LSI timer chips interfaced to a 16-bit microcomputer. Once programmed from the host computer, this device is able to generate elaborate logic sequences on its 10 output lines without further interventions from the CPU. Powerful architecture introduces new possibilities over conventional memory-based timing simulators and word generators. Loop control on a given sequence of events, loop nesting, and various logic combinations can easily be implemented through a software interface, using a symbolic command language. Typical applications of such a device range from development, emulation, and test of integrated circuits, circuit boards, and communication systems to pulse-controlled instrumentation (radar, ultrasonic systems). A particular application to a pulsed Nuclear Magnetic Resonance (NMR) spectrometer is presented, along with customization of the device for generating four-channel radio-frequency pulses and the necessary sequence for subsequent data acquisition.

A 2D Material based Gate Tunable Memristive Device for Emulating Modulatory Input-dependent Hetero-synaptic Plasticity.

NASA Astrophysics Data System (ADS)

Yan, Xiaodong; Tian, He; Xie, Yujun; Kostelec, Andrew; Zhao, Huan; Cha, Judy J.; Tice, Jesse; Wang, Han

Modulatory input-dependent plasticity is a well-known type of hetero-synaptic response where the release of neuromodulators can alter the efficacy of neurotransmission in a nearby chemical synapse. Solid-state devices that can mimic such phenomenon are desirable for enhancing the functionality and reconfigurability of neuromorphic electronics. In this work, we demonstrated a tunable artificial synaptic device concept based on the properties of graphene and tin oxide that can mimic the modulatory input-dependent plasticity. By using graphene as the contact electrode, a third electrode terminal can be used to modulate the conductive filament formation in the vertical tin oxide based resistive memory device. The resulting synaptic characteristics of this device, in terms of the profile of synaptic weight change and the spike-timing-dependent-plasticity, is tunable with the bias at the modulating terminal. Furthermore, the synaptic response can be reconfigured between excitatory and inhibitory modes by this modulating bias. The operation mechanism of the device is studied with combined experimental and theoretical analysis. The device is attractive for application in neuromorphic electronics. This work is supported by ARO and NG-ION2 at USC.

Digital avionics design and reliability analyzer

NASA Technical Reports Server (NTRS)

1981-01-01

The description and specifications for a digital avionics design and reliability analyzer are given. Its basic function is to provide for the simulation and emulation of the various fault-tolerant digital avionic computer designs that are developed. It has been established that hardware emulation at the gate-level will be utilized. The primary benefit of emulation to reliability analysis is the fact that it provides the capability to model a system at a very detailed level. Emulation allows the direct insertion of faults into the system, rather than waiting for actual hardware failures to occur. This allows for controlled and accelerated testing of system reaction to hardware failures. There is a trade study which leads to the decision to specify a two-machine system, including an emulation computer connected to a general-purpose computer. There is also an evaluation of potential computers to serve as the emulation computer.

Diagnostic emulation: Implementation and user's guide

NASA Technical Reports Server (NTRS)

Becher, Bernice

1987-01-01

The Diagnostic Emulation Technique was developed within the System Validation Methods Branch as a part of the development of methods for the analysis of the reliability of highly reliable, fault tolerant digital avionics systems. This is a general technique which allows for the emulation of a digital hardware system. The technique is general in the sense that it is completely independent of the particular target hardware which is being emulated. Parts of the system are described and emulated at the logic or gate level, while other parts of the system are described and emulated at the functional level. This algorithm allows for the insertion of faults into the system, and for the observation of the response of the system to these faults. This allows for controlled and accelerated testing of system reaction to hardware failures in the target machine. This document describes in detail how the algorithm was implemented at NASA Langley Research Center and gives instructions for using the system.

Space Communications Emulation Facility

NASA Technical Reports Server (NTRS)

Hill, Chante A.

2004-01-01

Establishing space communication between ground facilities and other satellites is a painstaking task that requires many precise calculations dealing with relay time, atmospheric conditions, and satellite positions, to name a few. The Space Communications Emulation Facility (SCEF) team here at NASA is developing a facility that will approximately emulate the conditions in space that impact space communication. The emulation facility is comprised of a 32 node distributed cluster of computers; each node representing a satellite or ground station. The objective of the satellites is to observe the topography of the Earth (water, vegetation, land, and ice) and relay this information back to the ground stations. Software originally designed by the University of Kansas, labeled the Emulation Manager, controls the interaction of the satellites and ground stations, as well as handling the recording of data. The Emulation Manager is installed on a Linux Operating System, employing both Java and C++ programming codes. The emulation scenarios are written in extensible Markup Language, XML. XML documents are designed to store, carry, and exchange data. With XML documents data can be exchanged between incompatible systems, which makes it ideal for this project because Linux, MAC and Windows Operating Systems are all used. Unfortunately, XML documents cannot display data like HTML documents. Therefore, the SCEF team uses XML Schema Definition (XSD) or just schema to describe the structure of an XML document. Schemas are very important because they have the capability to validate the correctness of data, define restrictions on data, define data formats, and convert data between different data types, among other things. At this time, in order for the Emulation Manager to open and run an XML emulation scenario file, the user must first establish a link between the schema file and the directory under which the XML scenario files are saved. This procedure takes place on the command line on the Linux Operating System. Once this link has been established the Emulation manager validates all the XML files in that directory against the schema file, before the actual scenario is run. Using some very sophisticated commercial software called the Satellite Tool Kit (STK) installed on the Linux box, the Emulation Manager is able to display the data and graphics generated by the execution of a XML emulation scenario file. The Emulation Manager software is written in JAVA programming code. Since the SCEF project is in the developmental stage, the source code for this type of software is being modified to better fit the requirements of the SCEF project. Some parameters for the emulation are hard coded, set at fixed values. Members of the SCEF team are altering the code to allow the user to choose the values of these hard coded parameters by inserting a toolbar onto the preexisting GUI.

Material requirements for bio-inspired sensing systems

NASA Astrophysics Data System (ADS)

Biggins, Peter; Lloyd, Peter; Salmond, David; Kusterbeck, Anne

2008-10-01

The aim of developing bio-inspired sensing systems is to try and emulate the amazing sensitivity and specificity observed in the natural world. These capabilities have evolved, often for specific tasks, which provide the organism with an advantage in its fight to survive and prosper. Capabilities cover a wide range of sensing functions including vision, temperature, hearing, touch, taste and smell. For some functions, the capabilities of natural systems are still greater than that achieved by traditional engineering solutions; a good example being a dog's sense of smell. Furthermore, attempting to emulate aspects of biological optics, processing and guidance may lead to more simple and effective devices. A bio-inspired sensing system is much more than the sensory mechanism. A system will need to collect samples, especially if pathogens or chemicals are of interest. Other functions could include the provision of power, surfaces and receptors, structure, locomotion and control. In fact it is possible to conceive of a complete bio-inspired system concept which is likely to be radically different from more conventional approaches. This concept will be described and individual component technologies considered.

Increased levels of circulating platelet-derived microparticles are associated with metastatic cutaneous melanoma.

PubMed

Moreau, Joséphine; Pelletier, Fabien; Biichle, Sabeha; Mourey, Guillaume; Puyraveau, Marc; Badet, Nicolas; Caubet, Matthieu; Laresche, Claire; Garnache-Ottou, Francine; Saas, Philippe; Seilles, Estelle; Aubin, François

2017-10-01

We investigated the plasma levels of PMPs in patients with 45 stage III and 45 stage IV melanoma. PMPs were characterised by flow cytometry and their thrombogenic activity. We also investigated the link between PMPs circulating levels and tumor burden. The circulating levels of PMPs were significantly higher in stage IV (8500 μL -1 ) than in patients with stage III (2041 μL -1 ) melanoma (P=.0001). We calculated a highly specific (93.3%) and predictive (91.7%) cut-off value (5311 μL -1 ) allowing the distinction between high-risk stage III and metastatic stage IV melanoma. The thrombogenic activity of PMPs was significantly higher in patients with stage IV melanoma (clotting time: 40.7 second vs 65 second, P=.0001). There was no significant association between the radiological tumoral syndrome and the plasma level of PMPs. Our data suggest the role of PMPs in metastatic progression of melanoma. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Geometric Optimization for Non-Thrombogenicity of a Centrifugal Blood Pump through Flow Visualization

NASA Astrophysics Data System (ADS)

Toyoda, Masahiro; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi; Tsutsui, Tatsuo; Sankai, Yoshiyuki

A monopivot centrifugal blood pump, whose impeller is supported with a pivot bearing and a passive magnetic bearing, is under development for implantable artificial heart. The hemolysis level is less than that of commercial centrifugal pumps and the pump size is as small as 160 mL in volume. To solve a problem of thrombus caused by fluid dynamics, flow visualization experiments and animal experiments have been undertaken. For flow visualization a three-fold scale-up model, high-speed video system, and particle tracking velocimetry software were used. To verify non-thrombogenicity one-week animal experiments were conducted with sheep. The initially observed thrombus around the pivot was removed through unifying the separate washout holes to a small centered hole to induce high shear around the pivot. It was found that the thrombus contours corresponded to the shear rate of 300s-1 for red thrombus and 1300-1700s-1 for white thrombus, respectively. Thus flow visualization technique was found to be a useful tool to predict thrombus location.

Electric-field-controlled interface dipole modulation for Si-based memory devices.

PubMed

Miyata, Noriyuki

2018-05-31

Various nonvolatile memory devices have been investigated to replace Si-based flash memories or emulate synaptic plasticity for next-generation neuromorphic computing. A crucial criterion to achieve low-cost high-density memory chips is material compatibility with conventional Si technologies. In this paper, we propose and demonstrate a new memory concept, interface dipole modulation (IDM) memory. IDM can be integrated as a Si field-effect transistor (FET) based memory device. The first demonstration of this concept employed a HfO 2 /Si MOS capacitor where the interface monolayer (ML) TiO 2 functions as a dipole modulator. However, this configuration is unsuitable for Si-FET-based devices due to its large interface state density (D it ). Consequently, we propose, a multi-stacked amorphous HfO 2 /1-ML TiO 2 /SiO 2 IDM structure to realize a low D it and a wide memory window. Herein we describe the quasi-static and pulse response characteristics of multi-stacked IDM MOS capacitors and demonstrate flash-type and analog memory operations of an IDM FET device.

Computer-Graphics Emulation of Chemical Instrumentation: Absorption Spectrophotometers.

ERIC Educational Resources Information Center

Gilbert, D. D.; And Others

1982-01-01

Describes interactive, computer-graphics program emulating behavior of high resolution, ultraviolet-visible analog recording spectrophotometer. Graphics terminal behaves as recording absorption spectrophotometer. Objective of the emulation is study of optimization of the instrument to yield accurate absorption spectra, including…

Using a Gaussian Process Emulator for Data-driven Surrogate Modelling of a Complex Urban Drainage Simulator

NASA Astrophysics Data System (ADS)

Bellos, V.; Mahmoodian, M.; Leopold, U.; Torres-Matallana, J. A.; Schutz, G.; Clemens, F.

2017-12-01

Surrogate models help to decrease the run-time of computationally expensive, detailed models. Recent studies show that Gaussian Process Emulators (GPE) are promising techniques in the field of urban drainage modelling. However, this study focusses on developing a GPE-based surrogate model for later application in Real Time Control (RTC) using input and output time series of a complex simulator. The case study is an urban drainage catchment in Luxembourg. A detailed simulator, implemented in InfoWorks ICM, is used to generate 120 input-output ensembles, from which, 100 are used for training the emulator and 20 for validation of the results. An ensemble of historical rainfall events with 2 hours duration and 10 minutes time steps are considered as the input data. Two example outputs, are selected as wastewater volume and total COD concentration in a storage tank in the network. The results of the emulator are tested with unseen random rainfall events from the ensemble dataset. The emulator is approximately 1000 times faster than the original simulator for this small case study. Whereas the overall patterns of the simulator are matched by the emulator, in some cases the emulator deviates from the simulator. To quantify the accuracy of the emulator in comparison with the original simulator, Nash-Sutcliffe efficiency (NSE) between the emulator and simulator is calculated for unseen rainfall scenarios. The range of NSE for the case of tank volume is from 0.88 to 0.99 with a mean value of 0.95, whereas for COD is from 0.71 to 0.99 with a mean value of 0.92. The emulator is able to predict the tank volume with higher accuracy as the relationship between rainfall intensity and tank volume is linear. For COD, which has a non-linear behaviour, the predictions are less accurate and more uncertain, in particular when rainfall intensity increases. This predictions were improved by including a larger amount of training data for the higher rainfall intensities. It was observed that, the accuracy of the emulator predictions depends on the ensemble training dataset design and the amount of data fed. Finally, more investigation is required to test the possibility of applying this type of fast emulators for model-based RTC applications in which limited number of inputs and outputs are considered in a short prediction horizon.

High Fidelity Simulations of Large-Scale Wireless Networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Onunkwo, Uzoma; Benz, Zachary

The worldwide proliferation of wireless connected devices continues to accelerate. There are 10s of billions of wireless links across the planet with an additional explosion of new wireless usage anticipated as the Internet of Things develops. Wireless technologies do not only provide convenience for mobile applications, but are also extremely cost-effective to deploy. Thus, this trend towards wireless connectivity will only continue and Sandia must develop the necessary simulation technology to proactively analyze the associated emerging vulnerabilities. Wireless networks are marked by mobility and proximity-based connectivity. The de facto standard for exploratory studies of wireless networks is discrete event simulationsmore » (DES). However, the simulation of large-scale wireless networks is extremely difficult due to prohibitively large turnaround time. A path forward is to expedite simulations with parallel discrete event simulation (PDES) techniques. The mobility and distance-based connectivity associated with wireless simulations, however, typically doom PDES and fail to scale (e.g., OPNET and ns-3 simulators). We propose a PDES-based tool aimed at reducing the communication overhead between processors. The proposed solution will use light-weight processes to dynamically distribute computation workload while mitigating communication overhead associated with synchronizations. This work is vital to the analytics and validation capabilities of simulation and emulation at Sandia. We have years of experience in Sandia’s simulation and emulation projects (e.g., MINIMEGA and FIREWHEEL). Sandia’s current highly-regarded capabilities in large-scale emulations have focused on wired networks, where two assumptions prevent scalable wireless studies: (a) the connections between objects are mostly static and (b) the nodes have fixed locations.« less

Evaluating Emulation-based Models of Distributed Computing Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, Stephen T.; Gabert, Kasimir G.; Tarman, Thomas D.

Emulation-based models of distributed computing systems are collections of virtual ma- chines, virtual networks, and other emulation components configured to stand in for oper- ational systems when performing experimental science, training, analysis of design alterna- tives, test and evaluation, or idea generation. As with any tool, we should carefully evaluate whether our uses of emulation-based models are appropriate and justified. Otherwise, we run the risk of using a model incorrectly and creating meaningless results. The variety of uses of emulation-based models each have their own goals and deserve thoughtful evaluation. In this paper, we enumerate some of these uses andmore » describe approaches that one can take to build an evidence-based case that a use of an emulation-based model is credible. Predictive uses of emulation-based models, where we expect a model to tell us something true about the real world, set the bar especially high and the principal evaluation method, called validation , is comensurately rigorous. We spend the majority of our time describing and demonstrating the validation of a simple predictive model using a well-established methodology inherited from decades of development in the compuational science and engineering community.« less

Endothelial Microparticles From Acute Coronary Syndrome Patients Induce Premature Coronary Artery Endothelial Cell Aging and Thrombogenicity: Role of the Ang II/AT1 Receptor/NADPH Oxidase-Mediated Activation of MAPKs and PI3-Kinase Pathways.

PubMed

Abbas, Malak; Jesel, Laurence; Auger, Cyril; Amoura, Lamia; Messas, Nathan; Manin, Guillaume; Rumig, Cordula; León-González, Antonio J; Ribeiro, Thais P; Silva, Grazielle C; Abou-Merhi, Raghida; Hamade, Eva; Hecker, Markus; Georg, Yannick; Chakfe, Nabil; Ohlmann, Patrick; Schini-Kerth, Valérie B; Toti, Florence; Morel, Olivier

2017-01-17

Microparticles (MPs) have emerged as a surrogate marker of endothelial dysfunction and cardiovascular risk. This study examined the potential of MPs from senescent endothelial cells (ECs) or from patients with acute coronary syndrome (ACS) to promote premature EC aging and thrombogenicity. Primary porcine coronary ECs were isolated from the left circumflex coronary artery. MPs were prepared from ECs and venous blood from patients with ACS (n=30) and from healthy volunteers (n=4) by sequential centrifugation. The level of endothelial senescence was assessed as senescence-associated β-galactosidase activity using flow cytometry, oxidative stress using the redox-sensitive probe dihydroethidium, tissue factor activity using an enzymatic Tenase assay, the level of target protein expression by Western blot analysis, platelet aggregation using an aggregometer, and shear stress using a cone-and-plate viscometer. Senescence, as assessed by senescence-associated β-galactosidase activity, was induced by the passaging of porcine coronary artery ECs from passage P1 to P4, and was associated with a progressive shedding of procoagulant MPs. Exposure of P1 ECs to MPs shed from senescent P3 cells or circulating MPs from ACS patients induced increased senescence-associated β-galactosidase activity, oxidative stress, early phosphorylation of mitogen-activated protein kinases and Akt, and upregulation of p53, p21, and p16. Ex vivo, the prosenescent effect of circulating MPs from ACS patients was evidenced only under conditions of low shear stress. Depletion of endothelial-derived MPs from ACS patients reduced the induction of senescence. Prosenescent MPs promoted EC thrombogenicity through tissue factor upregulation, shedding of procoagulant MPs, endothelial nitric oxide synthase downregulation, and reduced nitric oxide-mediated inhibition of platelet aggregation. These MPs exhibited angiotensin-converting enzyme activity and upregulated AT1 receptors and angiotensin-converting enzyme in P1 ECs. Losartan, an AT1 receptor antagonist, and inhibitors of either mitogen-activated protein kinases or phosphoinositide 3-kinase prevented the MP-induced endothelial senescence. These findings indicate that endothelial-derived MPs from ACS patients induce premature endothelial senescence under atheroprone low shear stress and thrombogenicity through angiotensin II-induced redox-sensitive activation of mitogen-activated protein kinases and phosphoinositide 3-kinase/Akt. They further suggest that targeting endothelial-derived MP shedding and their bioactivity may be a promising therapeutic strategy to limit the development of an endothelial dysfunction post-ACS. © 2016 American Heart Association, Inc.

Effects of exchanging carbohydrate or monounsaturated fat with saturated fat on inflammatory and thrombogenic responses in subjects with abdominal obesity: A randomized controlled trial.

PubMed

Teng, Kim-Tiu; Chang, Lin Faun; Vethakkan, Shireene Ratna; Nesaretnam, Kalanithi; Sanders, Tom A B

2017-10-01

Modification of the amount and type of dietary fat has diverse effects on cardiovascular risk. We recruited 54 abdominally obese subjects to participate in a prospective cross-over design, single-blind trial comparing isocaloric 2000 kcal MUFA or carbohydrate-enriched diet with SFA-enriched diet (control). The control diet consisted of 15E% protein, 53E% carbohydrate and 32E% fat (12E% SFA, 13E% MUFA). A total of ∼7E% of MUFA or refined carbohydrate was exchanged with SFA in the MUFA-rich and carbohydrate-rich diets respectively for 6-weeks. Blood samples were collected at fasting upon trial commencement and at week-5 and 6 of each dietary-intervention phase to measure levels of cytokines (IL-6, IL-1β), C-reactive protein (CRP), thrombogenic markers (E-selectin, PAI-1, D-dimer) and lipid subfractions. Radial pulse wave analysis and a 6-h postprandial mixed meal challenge were carried out at week-6 of each dietary intervention. Blood samples were collected at fasting, 15 and 30 min and hourly intervals thereafter till 6 h after a mixed meal challenge (muffin and milkshake) with SFA or MUFA (872.5 kcal, 50 g fat, 88 g carbohydrates) or CARB (881.3 kcal, 20 g fat, 158 g carbohydrates)- enrichment corresponding to the background diets. No significant differences in fasting inflammatory and thrombogenic factors were noted between diets (P > 0.05). CARB meal was found to increase plasma IL-6 whereas MUFA meal elevated plasma D-dimer postprandially compared with SAFA meal (P < 0.05). Comparing the 3 meals, there were similar postprandial elevations in IL-6 and D-dimer and postprandial reductions in PAI-1, augmentation index and pressure (time effect: P < 0.05). CARB diet was found to reduce HDL 3 by 7.8% and increase small dense HDL (sdHDL) by 8.6% compared with SFA diet (P < 0.05). SFA diet increased large HDL subfractions compared with both CARB and MUFA diets by 4.9% and 6.6% (P < 0.05), respectively. Overall, the evidence presented in this study suggests that the replacement of SFA with MUFA or refined carbohydrates may not improve inflammatory and thrombogenic markers in abdominally overweight individuals. Indeed increased refined carbohydrates consumption adversely impacts fasting HDL subfractions. This trial was registered under ClinicalTrials.gov. Identifier no. NCT01665482. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Precise replication of antireflective nanostructures from biotemplates

NASA Astrophysics Data System (ADS)

Gao, Hongjun; Liu, Zhongfan; Zhang, Jin; Zhang, Guoming; Xie, Guoyong

2007-03-01

The authors report herein a new type of nanonipple structures on the cicada's eye and the direct structural replication of the complex micro- and nanostructures for potential functional emulation. A two-step direct molding process is developed to replicate these natural micro- and nanostructures using epoxy resin with high fidelity, which demonstrates a general way of fabricating functional nanostructures by direct replication of natural biotemplates via a suitable physicochemical process. Measurements of spectral reflectance showed that this kind of replicated nanostructure has remarkable antireflective property, suggestive of its potential applications to optical devices.

Small Business Innovations (Exoskeletons)

NASA Technical Reports Server (NTRS)

1992-01-01

The Dexterous Hand Master (DHM), a 1989 winner of an R&D 100 Award, is an exoskeleton device for measuring the joints of the human hand with extreme precision. It was originally developed for NASA by Arthur D. Little, and is sold commercially by EXOS, Inc. The DHM is worn on the hand and connected to a computer that records hand motions. The resulting data is transmitted as control signals to robots and other computers, enabling robotic hands to emulate human hand actions. Two additional spinoff products were also inspired by the DHM.

High density electronic circuit and process for making

DOEpatents

Morgan, W.P.

1999-06-29

High density circuits with posts that protrude beyond one surface of a substrate to provide easy mounting of devices such as integrated circuits are disclosed. The posts also provide stress relief to accommodate differential thermal expansion. The process allows high interconnect density with fewer alignment restrictions and less wasted circuit area than previous processes. The resulting substrates can be test platforms for die testing and for multi-chip module substrate testing. The test platform can contain active components and emulate realistic operational conditions, replacing shorts/opens net testing. 8 figs.

An enhanced lumped element electrical model of a double barrier memristive device

NASA Astrophysics Data System (ADS)

Solan, Enver; Dirkmann, Sven; Hansen, Mirko; Schroeder, Dietmar; Kohlstedt, Hermann; Ziegler, Martin; Mussenbrock, Thomas; Ochs, Karlheinz

2017-05-01

The massive parallel approach of neuromorphic circuits leads to effective methods for solving complex problems. It has turned out that resistive switching devices with a continuous resistance range are potential candidates for such applications. These devices are memristive systems—nonlinear resistors with memory. They are fabricated in nanotechnology and hence parameter spread during fabrication may aggravate reproducible analyses. This issue makes simulation models of memristive devices worthwhile. Kinetic Monte-Carlo simulations based on a distributed model of the device can be used to understand the underlying physical and chemical phenomena. However, such simulations are very time-consuming and neither convenient for investigations of whole circuits nor for real-time applications, e.g. emulation purposes. Instead, a concentrated model of the device can be used for both fast simulations and real-time applications, respectively. We introduce an enhanced electrical model of a valence change mechanism (VCM) based double barrier memristive device (DBMD) with a continuous resistance range. This device consists of an ultra-thin memristive layer sandwiched between a tunnel barrier and a Schottky-contact. The introduced model leads to very fast simulations by using usual circuit simulation tools while maintaining physically meaningful parameters. Kinetic Monte-Carlo simulations based on a distributed model and experimental data have been utilized as references to verify the concentrated model.

Direct-coupled microcomputer-based building emulator for building energy management and control systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lam, H.N.

1999-07-01

In this paper, the development and implementation of a direct-coupled building emulator for a building energy management and control system (EMCS) is presented. The building emulator consists of a microcomputer and a computer model of an air-conditioning system implemented in a modular dynamic simulation software package for direct-coupling to an EMCS, without using analog-to-digital and digital-to-analog converters. The building emulator can be used to simulate in real time the behavior of the air-conditioning system under a given operating environment and subject to a given usage pattern. Software modules for data communication, graphical display, dynamic data exchange, and synchronization of simulationmore » outputs with real time have been developed to achieve direct digital data transfer between the building emulator and a commercial EMCS. Based on the tests conducted, the validity of the building emulator has been established and the proportional-plus-integral control function of the EMCS assessed.« less

Emulation for probabilistic weather forecasting

NASA Astrophysics Data System (ADS)

Cornford, Dan; Barillec, Remi

2010-05-01

Numerical weather prediction models are typically very expensive to run due to their complexity and resolution. Characterising the sensitivity of the model to its initial condition and/or to its parameters requires numerous runs of the model, which is impractical for all but the simplest models. To produce probabilistic forecasts requires knowledge of the distribution of the model outputs, given the distribution over the inputs, where the inputs include the initial conditions, boundary conditions and model parameters. Such uncertainty analysis for complex weather prediction models seems a long way off, given current computing power, with ensembles providing only a partial answer. One possible way forward that we develop in this work is the use of statistical emulators. Emulators provide an efficient statistical approximation to the model (or simulator) while quantifying the uncertainty introduced. In the emulator framework, a Gaussian process is fitted to the simulator response as a function of the simulator inputs using some training data. The emulator is essentially an interpolator of the simulator output and the response in unobserved areas is dictated by the choice of covariance structure and parameters in the Gaussian process. Suitable parameters are inferred from the data in a maximum likelihood, or Bayesian framework. Once trained, the emulator allows operations such as sensitivity analysis or uncertainty analysis to be performed at a much lower computational cost. The efficiency of emulators can be further improved by exploiting the redundancy in the simulator output through appropriate dimension reduction techniques. We demonstrate this using both Principal Component Analysis on the model output and a new reduced-rank emulator in which an optimal linear projection operator is estimated jointly with other parameters, in the context of simple low order models, such as the Lorenz 40D system. We present the application of emulators to probabilistic weather forecasting, where the construction of the emulator training set replaces the traditional ensemble model runs. Thus the actual forecast distributions are computed using the emulator conditioned on the ‘ensemble runs' which are chosen to explore the plausible input space using relatively crude experimental design methods. One benefit here is that the ensemble does not need to be a sample from the true distribution of the input space, rather it should cover that input space in some sense. The probabilistic forecasts are computed using Monte Carlo methods sampling from the input distribution and using the emulator to produce the output distribution. Finally we discuss the limitations of this approach and briefly mention how we might use similar methods to learn the model error within a framework that incorporates a data assimilation like aspect, using emulators and learning complex model error representations. We suggest future directions for research in the area that will be necessary to apply the method to more realistic numerical weather prediction models.

Molecules for security measures: from keypad locks to advanced communication protocols.

PubMed

Andréasson, J; Pischel, U

2018-04-03

The idea of using molecules in the context of information security has sparked the interest of researchers from many scientific disciplines. This is clearly manifested in the diversity of the molecular platforms and the analytical techniques used for this purpose, some of which we highlight in this Tutorial Review. Moreover, those molecular systems can be used to emulate a broad spectrum of security measures. For a long time, molecular keypad locks enjoyed a clear preference and the review starts off with a description of how these devices developed. In the last few years, however, the field has evolved into something larger. Examples include more complex authentication protocols (multi-factor authentication and one-time passwords), the recognition of erroneous procedures in data transmission (parity devices), as well as steganographic and cryptographic protection.

A multi-stimuli responsive switch as a fluorescent molecular analogue of transistors† †Electronic supplementary information (ESI) available: Detailed experimental procedures and additional data on the characterization of 1. See DOI: 10.1039/c5sc03395k Click here for additional data file.

PubMed Central

Gallardo, Iluminada; Morais, Sandy; Prats, Gemma

2016-01-01

Although the quantum nature of molecules makes them specially suitable for mimicking the operation of digital electronic elements, molecular compounds can also be envisioned to emulate the behavior of analog devices. In this work we report a novel fluorescent three-state switch capable of reproducing the analog response of transistors, an ubiquitous device in modern electronics. Exploiting the redox and thermal sensitivity of this compound, the amplitude of its fluorescence emission can be continuously modulated, in a similar way as the output current in a transistor is amplified by the gate-to-source voltage. PMID:28959394

B-vitamin deficiency is protective against DSS-induced colitis in mice

USDA-ARS?s Scientific Manuscript database

Vitamin deficiencies are common in patients with inflammatory bowel disease (IBD). Homocysteine (Hcys) is a thrombogenic amino acid produced from methionine (Met) and its increase in IBD patients indicates a disruption of Met metabolism, yet the role of Hcys and Met metabolism in IBD is not well und...

Personal-Computer Video-Terminal Emulator

NASA Technical Reports Server (NTRS)

Buckley, R. H.; Koromilas, A.; Smith, R. M.; Lee, G. E.; Giering, E. W.

1985-01-01

OWL-1200 video terminal emulator has been written for IBM Personal Computer. The OWL-1200 is a simple user terminal with some intelligent capabilities. These capabilities include screen formatting and block transmission of data. Emulator is written in PASCAL and Assembler for the IBM Personal Computer operating under DOS 1.1.

Megatux

DOE Office of Scientific and Technical Information (OSTI.GOV)

2012-09-25

The Megatux platform enables the emulation of large scale (multi-million node) distributed systems. In particular, it allows for the emulation of large-scale networks interconnecting a very large number of emulated computer systems. It does this by leveraging virtualization and associated technologies to allow hundreds of virtual computers to be hosted on a single moderately sized server or workstation. Virtualization technology provided by modern processors allows for multiple guest OSs to run at the same time, sharing the hardware resources. The Megatux platform can be deployed on a single PC, a small cluster of a few boxes or a large clustermore » of computers. With a modest cluster, the Megatux platform can emulate complex organizational networks. By using virtualization, we emulate the hardware, but run actual software enabling large scale without sacrificing fidelity.« less

Beyond Moore's law: towards competitive quantum devices

NASA Astrophysics Data System (ADS)

Troyer, Matthias

2015-05-01

A century after the invention of quantum theory and fifty years after Bell's inequality we see the first quantum devices emerge as products that aim to be competitive with the best classical computing devices. While a universal quantum computer of non-trivial size is still out of reach there exist a number commercial and experimental devices: quantum random number generators, quantum simulators and quantum annealers. In this colloquium I will present some of these devices and validation tests we performed on them. Quantum random number generators use the inherent randomness in quantum measurements to produce true random numbers, unlike classical pseudorandom number generators which are inherently deterministic. Optical lattice emulators use ultracold atomic gases in optical lattices to mimic typical models of condensed matter physics. In my talk I will focus especially on the devices built by Canadian company D-Wave systems, which are special purpose quantum simulators for solving hard classical optimization problems. I will review the controversy around the quantum nature of these devices and will compare them to state of the art classical algorithms. I will end with an outlook towards universal quantum computing and end with the question: which important problems that are intractable even for post-exa-scale classical computers could we expect to solve once we have a universal quantum computer?

Processor Emulator with Benchmark Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lloyd, G. Scott; Pearce, Roger; Gokhale, Maya

2015-11-13

A processor emulator and a suite of benchmark applications have been developed to assist in characterizing the performance of data-centric workloads on current and future computer architectures. Some of the applications have been collected from other open source projects. For more details on the emulator and an example of its usage, see reference [1].

The Ghost Condition: Imitation Versus Emulation in Young Children's Observational Learning.

ERIC Educational Resources Information Center

Thompson, Doreen E.; Russell, James

2004-01-01

Although observational learning by children may occur through imitating a modeler's actions, it can also occur through learning about an object's dynamic affordances- a process that M. Tomasello (1996) calls "emulation." The relative contributions of imitation and emulation within observational learning were examined in a study with 14- to…

The Use and Abuses of Emulation as a Pedagogical Practice

ERIC Educational Resources Information Center

Jonas, Mark E.; Chambers, Drew W.

2017-01-01

From the late eighteenth through the end of the nineteenth century, educational philosophers and practitioners debated the benefits and shortcomings of the use of emulation in schools. During this period, "emulation" referred to a pedagogy that leveraged comparisons between students as a tool to motivate them to higher achievement. Many…

An intelligent remote monitoring system for artificial heart.

PubMed

Choi, Jaesoon; Park, Jun W; Chung, Jinhan; Min, Byoung G

2005-12-01

A web-based database system for intelligent remote monitoring of an artificial heart has been developed. It is important for patients with an artificial heart implant to be discharged from the hospital after an appropriate stabilization period for better recovery and quality of life. Reliable continuous remote monitoring systems for these patients with life support devices are gaining practical meaning. The authors have developed a remote monitoring system for this purpose that consists of a portable/desktop monitoring terminal, a database for continuous recording of patient and device status, a web-based data access system with which clinicians can access real-time patient and device status data and past history data, and an intelligent diagnosis algorithm module that noninvasively estimates blood pump output and makes automatic classification of the device status. The system has been tested with data generation emulators installed on remote sites for simulation study, and in two cases of animal experiments conducted at remote facilities. The system showed acceptable functionality and reliability. The intelligence algorithm also showed acceptable practicality in an application to animal experiment data.

Hybrid Spintronic-CMOS Spiking Neural Network with On-Chip Learning: Devices, Circuits, and Systems

NASA Astrophysics Data System (ADS)

Sengupta, Abhronil; Banerjee, Aparajita; Roy, Kaushik

2016-12-01

Over the past decade, spiking neural networks (SNNs) have emerged as one of the popular architectures to emulate the brain. In SNNs, information is temporally encoded and communication between neurons is accomplished by means of spikes. In such networks, spike-timing-dependent plasticity mechanisms require the online programing of synapses based on the temporal information of spikes transmitted by spiking neurons. In this work, we propose a spintronic synapse with decoupled spike-transmission and programing-current paths. The spintronic synapse consists of a ferromagnet-heavy-metal heterostructure where the programing current through the heavy metal generates spin-orbit torque to modulate the device conductance. Low programing energy and fast programing times demonstrate the efficacy of the proposed device as a nanoelectronic synapse. We perform a simulation study based on an experimentally benchmarked device-simulation framework to demonstrate the interfacing of such spintronic synapses with CMOS neurons and learning circuits operating in the transistor subthreshold region to form a network of spiking neurons that can be utilized for pattern-recognition problems.

Idols as Sunshine or Road Signs: Comparing Absorption-Addiction Idolatry With Identification-Emulation Idolatry.

PubMed

Cheung, Chau-Kiu; Yue, Xiao Dong

2018-01-01

This study seeks to contrast absorption-addiction idolatry and identification-emulation idolatry. Whereas absorption-addiction idolatry progresses from entertainment/socializing to personalizing and obsession about the idol, identification-emulation idolatry unfolds in terms of identification, attachment, romantization, idealization, and consumption about the idol or his or her derivatives. Based on a sample of 1310 secondary school and university students in Hong Kong, the study verified the original factor model composed of five first-order identification-emulation idolatry and three first-order absorption-addiction idolatry factors, with the latter more predictable by fans' club membership.

Design of BLDCM emulator for transmission control units

NASA Astrophysics Data System (ADS)

Liu, Chang; He, Yongyi; Zhang, Bodong

2018-04-01

According to the testing requirements of the transmission control unit, a brushless DC motor emulating system is designed based on motor simulation and power hardware-in-the-loop. The discrete motor model is established and a real-time numerical method is designed to solve the motor states. The motor emulator directly interacts with power stage of the transmission control unit using a power-efficient circuit topology and is compatible with sensor-less control. Experiments on a laboratory prototype help to verify that the system can emulate the real motor currents and voltages whenever the motor is starting up or suddenly loaded.

A 1.26 μW Cytomimetic IC Emulating Complex Nonlinear Mammalian Cell Cycle Dynamics: Synthesis, Simulation and Proof-of-Concept Measured Results.

PubMed

Houssein, Alexandros; Papadimitriou, Konstantinos I; Drakakis, Emmanuel M

2015-08-01

Cytomimetic circuits represent a novel, ultra low-power, continuous-time, continuous-value class of circuits, capable of mapping on silicon cellular and molecular dynamics modelled by means of nonlinear ordinary differential equations (ODEs). Such monolithic circuits are in principle able to emulate on chip, single or multiple cell operations in a highly parallel fashion. Cytomimetic topologies can be synthesized by adopting the Nonlinear Bernoulli Cell Formalism (NBCF), a mathematical framework that exploits the striking similarities between the equations describing weakly-inverted Metal-Oxide Semiconductor (MOS) devices and coupled nonlinear ODEs, typically appearing in models of naturally encountered biochemical systems. The NBCF maps biological state variables onto strictly positive subthreshold MOS circuit currents. This paper presents the synthesis, the simulation and proof-of-concept chip results corresponding to the emulation of a complex cellular network mechanism, the skeleton model for the network of Cyclin-dependent Kinases (CdKs) driving the mammalian cell cycle. This five variable nonlinear biological model, when appropriate model parameter values are assigned, can exhibit multiple oscillatory behaviors, varying from simple periodic oscillations, to complex oscillations such as quasi-periodicity and chaos. The validity of our approach is verified by simulated results with realistic process parameters from the commercially available AMS 0.35 μm technology and by chip measurements. The fabricated chip occupies an area of 2.27 mm2 and consumes a power of 1.26 μW from a power supply of 3 V. The presented cytomimetic topology follows closely the behavior of its biological counterpart, exhibiting similar time-dependent solutions of the Cdk complexes, the transcription factors and the proteins.

Targeting Heparin to Collagen within Extracellular Matrix Significantly Reduces Thrombogenicity and Improves Endothelialization of Decellularized Tissues.

PubMed

Jiang, Bin; Suen, Rachel; Wertheim, Jason A; Ameer, Guillermo A

2016-12-12

Thrombosis within small-diameter vascular grafts limits the development of bioartificial, engineered vascular conduits, especially those derived from extracellular matrix (ECM). Here we describe an easy-to-implement strategy to chemically modify vascular ECM by covalently linking a collagen binding peptide (CBP) to heparin to form a heparin derivative (CBP-heparin) that selectively binds a subset of collagens. Modification of ECM with CBP-heparin leads to increased deposition of functional heparin (by ∼7.2-fold measured by glycosaminoglycan composition) and a corresponding reduction in platelet binding (>70%) and whole blood clotting (>80%) onto the ECM. Furthermore, addition of CBP-heparin to the ECM stabilizes long-term endothelial cell attachment to the lumen of ECM-derived vascular conduits, potentially through recruitment of heparin-binding growth factors that ultimately improve the durability of endothelialization in vitro. Overall, our findings provide a simple yet effective method to increase deposition of functional heparin on the surface of ECM-based vascular grafts and thereby minimize thrombogenicity of decellularized tissue, overcoming a significant challenge in tissue engineering of bioartificial vessels and vascularized organs.

A magnetorheological haptic cue accelerator for manual transmission vehicles

NASA Astrophysics Data System (ADS)

Han, Young-Min; Noh, Kyung-Wook; Lee, Yang-Sub; Choi, Seung-Bok

2010-07-01

This paper proposes a new haptic cue function for manual transmission vehicles to achieve optimal gear shifting. This function is implemented on the accelerator pedal by utilizing a magnetorheological (MR) brake mechanism. By combining the haptic cue function with the accelerator pedal, the proposed haptic cue device can transmit the optimal moment of gear shifting for manual transmission to a driver without requiring the driver's visual attention. As a first step to achieve this goal, a MR fluid-based haptic device is devised to enable rotary motion of the accelerator pedal. Taking into account spatial limitations, the design parameters are optimally determined using finite element analysis to maximize the relative control torque. The proposed haptic cue device is then manufactured and its field-dependent torque and time response are experimentally evaluated. Then the manufactured MR haptic cue device is integrated with the accelerator pedal. A simple virtual vehicle emulating the operation of the engine of a passenger vehicle is constructed and put into communication with the haptic cue device. A feed-forward torque control algorithm for the haptic cue is formulated and control performances are experimentally evaluated and presented in the time domain.

System on a Chip Real-Time Emulation (SOCRE)

DTIC Science & Technology

2006-09-01

code ) i Table of Contents Preface...emulation platform included LDPC decoders, A/V and radio applications Port BEE flow to Emulation Platforms, SOC Technologies One of the key tasks of the...Once the design has been described within Simulink, the designer runs the BEE design flow within Matlab using the bee_xps interface. At this point

Emotions Targeting Moral Exemplarity: Making Sense of the Logical Geography of Admiration, Emulation and Elevation

ERIC Educational Resources Information Center

Kristjánsson, Kristján

2017-01-01

Despite renewed interest in moral role-modelling and its emotional underpinnings, further conceptual work is needed on the logical geography of the emotions purportedly driving it, in particular, admiration, emulation and elevation. In this article, I explore admiration (as understood by Linda Zagzebski), emulation (as understood by Aristotle) and…

A Fully-Passive Wireless Microsystem for Recording of Neuropotentials using RF Backscattering Methods

PubMed Central

Xu, Wencheng; Shekhar, Sameer; Abbaspour-Tamijani, Abbas; Towe, Bruce C.; Miranda, Félix A.; Chae, Junseok

2011-01-01

The ability to safely monitor neuropotentials is essential in establishing methods to study the brain. Current research focuses on the wireless telemetry aspect of implantable sensors in order to make these devices ubiquitous and safe. Chronic implants necessitate superior reliability and durability of the integrated electronics. The power consumption of implanted electronics must also be limited to within several milliwatts to microwatts to minimize heat trauma in the human body. In order to address these severe requirements, we developed an entirely passive and wireless microsystem for recording neuropotentials. An external interrogator supplies a fundamental microwave carrier to the microsystem. The microsystem comprises varactors that perform nonlinear mixing of neuropotential and fundamental carrier signals. The varactors generate third-order mixing products that are wirelessly backscattered to the external interrogator where the original neuropotential signals are recovered. Performance of the neuro-recording microsystem was demonstrated by wireless recording of emulated and in vivo neuropotentials. The obtained results were wireless recovery of neuropotentials as low as approximately 500 microvolts peak-to-peak (μVpp) with a bandwidth of 10 Hz to 3 kHz (for emulated signals) and with 128 epoch signal averaging of repetitive signals (for in vivo signals). PMID:22267898

Synaptic plasticity and memory functions achieved in a WO3-x-based nanoionics device by using the principle of atomic switch operation

NASA Astrophysics Data System (ADS)

Yang, Rui; Terabe, Kazuya; Yao, Yiping; Tsuruoka, Tohru; Hasegawa, Tsuyoshi; Gimzewski, James K.; Aono, Masakazu

2013-09-01

A compact neuromorphic nanodevice with inherent learning and memory properties emulating those of biological synapses is the key to developing artificial neural networks rivaling their biological counterparts. Experimental results showed that memorization with a wide time scale from volatile to permanent can be achieved in a WO3-x-based nanoionics device and can be precisely and cumulatively controlled by adjusting the device’s resistance state and input pulse parameters such as the amplitude, interval, and number. This control is analogous to biological synaptic plasticity including short-term plasticity, long-term potentiation, transition from short-term memory to long-term memory, forgetting processes for short- and long-term memory, learning speed, and learning history. A compact WO3-x-based nanoionics device with a simple stacked layer structure should thus be a promising candidate for use as an inorganic synapse in artificial neural networks due to its striking resemblance to the biological synapse.

Case-based reasoning emulation of persons for wheelchair navigation.

PubMed

Peula, Jose Manuel; Urdiales, Cristina; Herrero, Ignacio; Fernandez-Carmona, Manuel; Sandoval, Francisco

2012-10-01

Testing is a key stage in system development, particularly in systems such as a wheelchair, in which the final user is typically a disabled person. These systems have stringent safety requirements, requiring major testing with many different individuals. The best would be to have the wheelchair tested by many different end users, as each disability affects driving skills in a different way. Unfortunately, from a practical point of view it is difficult to engage end users as beta testers. Hence, testing often relies on simulations. Naturally, these simulations need to be as realistic as possible to make the system robust and safe before real tests can be accomplished. This work presents a tool to automatically test wheelchairs through realistic emulation of different wheelchair users. Our approach is based on extracting meaningful data from real users driving a power wheelchair autonomously. This data is then used to train a case-based reasoning (CBR) system that captures the specifics of the driver via learning. The resulting case-base is then used to emulate the driving behavior of that specific person in more complex situations or when a new assistive algorithm needs to be tested. CBR returns user's motion commands appropriate for each specific situation to add the human component to shared control systems. The proposed system has been used to emulate several power wheelchair users presenting different disabilities. Data to create this emulation was obtained from previous wheelchair navigation experiments with 35 volunteer in-patients presenting different degrees of disability. CBR was trained with a limited number of scenarios for each volunteer. Results proved that: (i) emulated and real users returned similar paths in the same scenario (maximum and mean path deviations are equal to 23 and 10cm, respectively) and similar efficiency; (ii) we established the generality of our approach taking a new path not present in the training traces; (iii) the emulated user is more realistic - path and efficiency are less homogeneous and smooth - than potential field approaches; and (iv) the system adequately emulates in-patients - maximum and mean path deviations are equal to 19 and 8.3cm approximately and efficiencies are similar - with specific disabilities (apraxia and dementia) obtaining different behaviors during emulation for each of the in-patients, as expected. The proposed system adequately emulates the driving behavior of people with different disabilities in indoor scenarios. This approach is suitable to emulate real users' driving behaviors for early testing stages of assistive navigation systems. Copyright © 2012 Elsevier B.V. All rights reserved.

QERx- A Faster than Real-Time Emulator for Space Processors

NASA Astrophysics Data System (ADS)

Carvalho, B.; Pidgeon, A.; Robinson, P.

2012-08-01

Developing software for space systems is challenging. Especially because, in order to be sure it can cope with the harshness of the environment and the imperative requirements and constrains imposed by the platform were it will run, it needs to be tested exhaustively. Software Validation Facilities (SVF) are known to the industry and developers, and provide the means to run the On-Board Software (OBSW) in a realistic environment, allowing the development team to debug and test the software.But the challenge is to be able to keep up with the performance of the new processors (LEON2 and LEON3), which need to be emulated within the SVF. Such processor emulators are also used in Operational Simulators, used to support mission preparation and train mission operators. These simulators mimic the satellite and its behaviour, as realistically as possible. For test/operational efficiency reasons and because they will need to interact with external systems, both these uses cases require the processor emulators to provide real-time, or faster, performance.It is known to the industry that the performance of previously available emulators is not enough to cope with the performance of the new processors available in the market. SciSys approached this problem with dynamic translation technology trying to keep costs down by avoiding a hardware solution and keeping the integration flexibility of full software emulation.SciSys presented “QERx: A High Performance Emulator for Software Validation and Simulations” [1], in a previous DASIA event. Since then that idea has evolved and QERx has been successfully validated. SciSys is now presenting QERx as a product that can be tailored to fit different emulation needs. This paper will present QERx latest developments and current status.

Oxide-based synaptic transistors gated by solution-processed gelatin electrolytes

NASA Astrophysics Data System (ADS)

He, Yinke; Sun, Jia; Qian, Chuan; Kong, Ling-An; Gou, Guangyang; Li, Hongjian

2017-04-01

In human brain, a large number of neurons are connected via synapses. Simulation of the synaptic behaviors using electronic devices is the most important step for neuromorphic systems. In this paper, proton conducting gelatin electrolyte-gated oxide field-effect transistors (FETs) were used for emulating synaptic functions, in which the gate electrode is regarded as pre-synaptic neuron and the channel layer as the post-synaptic neuron. In analogy to the biological synapse, a potential spike can be applied at the gate electrode and trigger ionic motion in the gelatin electrolyte, which in turn generates excitatory post-synaptic current (EPSC) in the channel layer. Basic synaptic behaviors including spike time-dependent EPSC, paired-pulse facilitation (PPF), self-adaptation, and frequency-dependent synaptic transmission were successfully mimicked. Such ionic/electronic hybrid devices are beneficial for synaptic electronics and brain-inspired neuromorphic systems.

Restenosis of the CYPHER-Select, TAXUS-Express, and Polyzene-F Nanocoated Cobalt-Chromium Stents in the Minipig Coronary Artery Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Radeleff, Boris, E-mail: Boris.radeleff@med.uni-heidelberg.de; Thierjung, Heidi; Stampfl, Ulrike

2008-09-15

PurposeTo date no direct experimental comparison between the CYPHER-Select and TAXUS-Express stents is available. Therefore, we investigated late in-stent stenosis, thrombogenicity, and inflammation, comparing the CYPHER-Select, TAXUS-Express, and custom-made cobalt chromium Polyzene-F nanocoated stents (CCPS) in the minipig coronary artery model.MethodsThe three stent types were implanted in the right coronary artery of 30 minipigs. The primary endpoint was in-stent stenosis assessed by quantitative angiography and microscopy. Secondary endpoints were inflammation and thrombogenicity evaluated by scores for inflammation and immunoreactivity (C-reactive protein and transforming growth factor beta). Follow-up was at 4 and 12 weeks.ResultsStent placement was successful in all animals; nomore » thrombus deposition occurred. Quantitative angiography did not depict statistically significant differences between the three stent types after 4 and 12 weeks. Quantitative microscopy at 4 weeks showed a statistically significant thicker neointima (p = 0.0431) for the CYPHER (105.034 {+-} 62.52 {mu}m) versus the TAXUS (74.864 {+-} 66.03 {mu}m) and versus the CCPS (63.542 {+-} 39.57 {mu}m). At 12 weeks there were no statistically significant differences. Inflammation scores at 4 weeks were significantly lower for the CCPS and CYPHER compared with the TAXUS stent (p = 0.0431). After 12 weeks statistical significance was only found for the CYPHER versus the TAXUS stent (p = 0.0431). The semiquantitative immunoreactivity scores for C-reactive protein and transforming growth factor beta showed no statistically significant differences between the three stent types after 4 and 12 weeks.ConclusionsThe CCPS provided effective control of late in-stent stenosis and thrombogenicity in this porcine model compared with the two drug-eluting stents. Its low inflammation score underscores its noninflammatory potential and might explain its equivalence to the two DES.« less

Vascular Nitric Oxide-Superoxide Balance and Thrombus Formation after Acute Exercise.

PubMed

Przyborowski, Kamil; Proniewski, Bartosz; Czarny, Joanna; Smeda, Marta; Sitek, Barbara; Zakrzewska, Agnieszka; Zoladz, Jerzy A; Chlopicki, Stefan

2018-02-21

An acute bout of strenuous exercise in humans results in transient impairment of NO-dependent function, but it remains unknown whether this phenomenon is associated with increased risk of post-exercise thrombotic events. This study aimed to evaluate effects of a single bout of exhaustive running in mice on the balance of vascular nitric oxide (NO)/reactive oxygen species (ROS) production, and on thrombogenicity. At different time-points (0h, 2h and 4h) after exercise and in sedentary C57BL/6 mice the production of NO and superoxide (O2) in aorta was measured by electron paramagnetic resonance (EPR) spin trapping and by dihydroethidium (DHE)/HPLC-based method, respectively, while collagen-induced thrombus formation was analyzed in a microchip-based flow-chamber system (T-TAS). We also measured pre- and post-exercise plasma concentration of nitrite/nitrate and 6-keto-PGF1α. An acute bout of exhaustive running in mice resulted in decreased production of NO and increased production of O2 in aorta, with maximum changes 2h after completion of exercise when compared to sedentary mice. However, platelet thrombus formation was not changed by exercise as evidenced by unaltered time to start of thrombus formation (T10) and capillary occlusion (OT), and total thrombogenicity (AUC) as measured in a flow-chamber system. Strenuous exercise increased the plasma concentration of nitrite but did not affect nitrate and 6-keto-PGF1α concentrations. An acute bout of strenuous exercise in mice reduced NO and in parallel increased O2 production in aorta. This response was most pronounced 2h after exercise. Surprisingly, the reduced NO and increased O2 production did not result in increased post-exercise platelet-dependent thrombogenicity. These results show that transient reduction in NO bioavailability, caused by exercise-induced oxidative stress, does not modify post-exercise thromboresistance in healthy mice.

Interference and memory capacity effects in memristive systems

NASA Astrophysics Data System (ADS)

Hermiz, John; Chang, Ting; Du, Chao; Lu, Wei

2013-02-01

Short-term memory implies the existence of a capacity limit beyond which memory cannot be securely formed and retained. The underlying mechanisms are believed to be two primary factors: decay and interference. Here, we demonstrate through both simulation and experiment that the memory capacity effect can be implemented in a parallel memristor circuit, where decay and interference are achieved by the inherent ion diffusion in the device and the competition for current supply in the circuit, respectively. This study suggests it is possible to emulate high-level biological behaviors with memristor circuits and will stimulate continued studies on memristor-based neuromorphic circuits.

Organic-based molecular switches for molecular electronics.

PubMed

Fuentes, Noelia; Martín-Lasanta, Ana; Alvarez de Cienfuegos, Luis; Ribagorda, Maria; Parra, Andres; Cuerva, Juan M

2011-10-05

In a general sense, molecular electronics (ME) is the branch of nanotechnology which studies the application of molecular building blocks for the fabrication of electronic components. Among the different types of molecules, organic compounds have been revealed as promising candidates for ME, due to the easy access, great structural diversity and suitable electronic and mechanical properties. Thanks to these useful capabilities, organic molecules have been used to emulate electronic devices at the nanoscopic scale. In this feature article, we present the diverse strategies used to develop organic switches towards ME with special attention to non-volatile systems.

The Signi?cance of Emulation in the Oral Interaction between Teacher and Students

ERIC Educational Resources Information Center

Kindeberg, Tina

2013-01-01

The lack of attention to the role of emotions generally has led modern learning theories to neglect the importance of emulation as a pedagogical support to students' learning. One reason could be that the influence of teacher personality is not considered in relation to learning outcome. Another reason may be that the concept of emulation has been…

THE MIRA–TITAN UNIVERSE: PRECISION PREDICTIONS FOR DARK ENERGY SURVEYS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heitmann, Katrin; Habib, Salman; Biswas, Rahul

2016-04-01

Large-scale simulations of cosmic structure formation play an important role in interpreting cosmological observations at high precision. The simulations must cover a parameter range beyond the standard six cosmological parameters and need to be run at high mass and force resolution. A key simulation-based task is the generation of accurate theoretical predictions for observables using a finite number of simulation runs, via the method of emulation. Using a new sampling technique, we explore an eight-dimensional parameter space including massive neutrinos and a variable equation of state of dark energy. We construct trial emulators using two surrogate models (the linear powermore » spectrum and an approximate halo mass function). The new sampling method allows us to build precision emulators from just 26 cosmological models and to systematically increase the emulator accuracy by adding new sets of simulations in a prescribed way. Emulator fidelity can now be continuously improved as new observational data sets become available and higher accuracy is required. Finally, using one ΛCDM cosmology as an example, we study the demands imposed on a simulation campaign to achieve the required statistics and accuracy when building emulators for investigations of dark energy.« less

The mira-titan universe. Precision predictions for dark energy surveys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heitmann, Katrin; Bingham, Derek; Lawrence, Earl

2016-03-28

Large-scale simulations of cosmic structure formation play an important role in interpreting cosmological observations at high precision. The simulations must cover a parameter range beyond the standard six cosmological parameters and need to be run at high mass and force resolution. A key simulation-based task is the generation of accurate theoretical predictions for observables using a finite number of simulation runs, via the method of emulation. Using a new sampling technique, we explore an eight-dimensional parameter space including massive neutrinos and a variable equation of state of dark energy. We construct trial emulators using two surrogate models (the linear powermore » spectrum and an approximate halo mass function). The new sampling method allows us to build precision emulators from just 26 cosmological models and to systematically increase the emulator accuracy by adding new sets of simulations in a prescribed way. Emulator fidelity can now be continuously improved as new observational data sets become available and higher accuracy is required. Finally, using one ΛCDM cosmology as an example, we study the demands imposed on a simulation campaign to achieve the required statistics and accuracy when building emulators for investigations of dark energy.« less

Network Modeling and Simulation Environment (NEMSE)

DTIC Science & Technology

2012-07-01

the NEMSE program investigated complex emulation techniques and selected compatible emulation techniques for all OSI network stack layers. Other...EMULAB; 2) Completed the selection of compatible emulation techniques that allows working with all layers of the Open System Interconnect ( OSI ...elements table, Figure 3, reconciles the various elements of NEMSE against the OSI stack and other functions. OSI Layer or Function EM UL AB NS 2

Generic Software for Emulating Multiprocessor Architectures.

DTIC Science & Technology

1985-05-01

RD-A157 662 GENERIC SOFTWARE FOR EMULATING MULTIPROCESSOR 1/2 AlRCHITECTURES(J) MASSACHUSETTS INST OF TECH CAMBRIDGE U LRS LAB FOR COMPUTER SCIENCE R...AREA & WORK UNIT NUMBERS MIT Laboratory for Computer Science 545 Technology Square Cambridge, MA 02139 ____________ I I. CONTROLLING OFFICE NAME AND...aide If neceeasy end Identify by block number) Computer architecture, emulation, simulation, dataf low 20. ABSTRACT (Continue an reverse slde It

Propulsion Electric Grid Simulator (PEGS) for Future Turboelectric Distributed Propulsion Aircraft

NASA Technical Reports Server (NTRS)

Choi, Benjamin B.; Morrison, Carlos; Dever, Timothy; Brown, Gerald V.

2014-01-01

NASA Glenn Research Center, in collaboration with the aerospace industry and academia, has begun the development of technology for a future hybrid-wing body electric airplane with a turboelectric distributed propulsion (TeDP) system. It is essential to design a subscale system to emulate the TeDP power grid, which would enable rapid analysis and demonstration of the proof-of-concept of the TeDP electrical system. This paper describes how small electrical machines with their controllers can emulate all the components in a TeDP power train. The whole system model in Matlab/Simulink was first developed and tested in simulation, and the simulation results showed that system dynamic characteristics could be implemented by using the closed-loop control of the electric motor drive systems. Then we designed a subscale experimental system to emulate the entire power system from the turbine engine to the propulsive fans. Firstly, we built a system to emulate a gas turbine engine driving a generator, consisting of two permanent magnet (PM) motors with brushless motor drives, coupled by a shaft. We programmed the first motor and its drive to mimic the speed-torque characteristic of the gas turbine engine, while the second motor and drive act as a generator and produce a torque load on the first motor. Secondly, we built another system of two PM motors and drives to emulate a motor driving a propulsive fan. We programmed the first motor and drive to emulate a wound-rotor synchronous motor. The propulsive fan was emulated by implementing fan maps and flight conditions into the fourth motor and drive, which produce a torque load on the driving motor. The stator of each PM motor is designed to travel axially to change the coupling between rotor and stator. This feature allows the PM motor to more closely emulate a wound-rotor synchronous machine. These techniques can convert the plain motor system into a unique TeDP power grid emulator that enables real-time simulation performance using hardware-in-the-loop (HIL).

Emulation of simulations of atmospheric dispersion at Fukushima for Sobol' sensitivity analysis

NASA Astrophysics Data System (ADS)

Girard, Sylvain; Korsakissok, Irène; Mallet, Vivien

2015-04-01

Polyphemus/Polair3D, from which derives IRSN's operational model ldX, was used to simulate the atmospheric dispersion at the Japan scale of radionuclides after the Fukushima disaster. A previous study with the screening method of Morris had shown that - The sensitivities depend a lot on the considered output; - Only a few of the inputs are non-influential on all considered outputs; - Most influential inputs have either non-linear effects or are interacting. These preliminary results called for a more detailed sensitivity analysis, especially regarding the characterization of interactions. The method of Sobol' allows for a precise evaluation of interactions but requires large simulation samples. Gaussian process emulators for each considered outputs were built in order to relieve this computational burden. Globally aggregated outputs proved to be easy to emulate with high accuracy, and associated Sobol' indices are in broad agreement with previous results obtained with the Morris method. More localized outputs, such as temporal averages of gamma dose rates at measurement stations, resulted in lesser emulator performances: tests simulations could not satisfactorily be reproduced by some emulators. These outputs are of special interest because they can be compared to available observations, for instance for calibration purpose. A thorough inspection of prediction residuals hinted that the model response to wind perturbations often behaved in very distinct regimes relatively to some thresholds. Complementing the initial sample with wind perturbations set to the extreme values allowed for sensible improvement of some of the emulators while other remained too unreliable to be used in a sensitivity analysis. Adaptive sampling or regime-wise emulation could be tried to circumvent this issue. Sobol' indices for local outputs revealed interesting patterns, mostly dominated by the winds, with very high interactions. The emulators will be useful for subsequent studies. Indeed, our goal is to characterize the model output uncertainty but too little information is available about input uncertainties. Hence, calibration of the input distributions with observation and a Bayesian approach seem necessary. This would probably involve methods such as MCMC which would be intractable without emulators.

Platelet Glycoprotein Ib-IX and Malignancy

DTIC Science & Technology

2010-09-01

provide a unique microenvironment supporting the accumulation of more platelets and the elaboration of a fibrin - rich network produced by coagulation...process and can initiate the formation of a platelet - rich thrombus by tethering the platelet to a thrombogenic surface. Several ligands binding to GP Ib... Platelet Glycoprotein Ib-IX and Malignancy PRINCIPAL INVESTIGATOR: Jerry Ware, Ph.D

Copy of Using Emulation and Simulation to Understand the Large-Scale Behavior of the Internet.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adalsteinsson, Helgi; Armstrong, Robert C.; Chiang, Ken

2008-10-01

We report on the work done in the late-start LDRDUsing Emulation and Simulation toUnderstand the Large-Scale Behavior of the Internet. We describe the creation of a researchplatform that emulates many thousands of machines to be used for the study of large-scale inter-net behavior. We describe a proof-of-concept simple attack we performed in this environment.We describe the successful capture of a Storm bot and, from the study of the bot and furtherliterature search, establish large-scale aspects we seek to understand via emulation of Storm onour research platform in possible follow-on work. Finally, we discuss possible future work.3

FPGA Based Reconfigurable ATM Switch Test Bed

NASA Technical Reports Server (NTRS)

Chu, Pong P.; Jones, Robert E.

1998-01-01

Various issues associated with "FPGA Based Reconfigurable ATM Switch Test Bed" are presented in viewgraph form. Specific topics include: 1) Network performance evaluation; 2) traditional approaches; 3) software simulation; 4) hardware emulation; 5) test bed highlights; 6) design environment; 7) test bed architecture; 8) abstract sheared-memory switch; 9) detailed switch diagram; 10) traffic generator; 11) data collection circuit and user interface; 12) initial results; and 13) the following conclusions: Advances in FPGA make hardware emulation feasible for performance evaluation, hardware emulation can provide several orders of magnitude speed-up over software simulation; due to the complexity of hardware synthesis process, development in emulation is much more difficult than simulation and requires knowledge in both networks and digital design.

Statistical evaluation of metal fill widths for emulated metal fill in parasitic extraction methodology

NASA Astrophysics Data System (ADS)

J-Me, Teh; Noh, Norlaili Mohd.; Aziz, Zalina Abdul

2015-05-01

In the chip industry today, the key goal of a chip development organization is to develop and market chips within a short time frame to gain foothold on market share. This paper proposes a design flow around the area of parasitic extraction to improve the design cycle time. The proposed design flow utilizes the usage of metal fill emulation as opposed to the current flow which performs metal fill insertion directly. By replacing metal fill structures with an emulation methodology in earlier iterations of the design flow, this is targeted to help reduce runtime in fill insertion stage. Statistical design of experiments methodology utilizing the randomized complete block design was used to select an appropriate emulated metal fill width to improve emulation accuracy. The experiment was conducted on test cases of different sizes, ranging from 1000 gates to 21000 gates. The metal width was varied from 1 x minimum metal width to 6 x minimum metal width. Two-way analysis of variance and Fisher's least significant difference test were used to analyze the interconnect net capacitance values of the different test cases. This paper presents the results of the statistical analysis for the 45 nm process technology. The recommended emulated metal fill width was found to be 4 x the minimum metal width.

Estimation of Quasi-Stiffness and Propulsive Work of the Human Ankle in the Stance Phase of Walking

PubMed Central

Shamaei, Kamran; Sawicki, Gregory S.; Dollar, Aaron M.

2013-01-01

Characterizing the quasi-stiffness and work of lower extremity joints is critical for evaluating human locomotion and designing assistive devices such as prostheses and orthoses intended to emulate the biological behavior of human legs. This work aims to establish statistical models that allow us to predict the ankle quasi-stiffness and net mechanical work for adults walking on level ground. During the stance phase of walking, the ankle joint propels the body through three distinctive phases of nearly constant stiffness known as the quasi-stiffness of each phase. Using a generic equation for the ankle moment obtained through an inverse dynamics analysis, we identify key independent parameters needed to predict ankle quasi-stiffness and propulsive work and also the functional form of each correlation. These parameters include gait speed, ankle excursion, and subject height and weight. Based on the identified form of the correlation and key variables, we applied linear regression on experimental walking data for 216 gait trials across 26 subjects (speeds from 0.75–2.63 m/s) to obtain statistical models of varying complexity. The most general forms of the statistical models include all the key parameters and have an R2 of 75% to 81% in the prediction of the ankle quasi-stiffnesses and propulsive work. The most specific models include only subject height and weight and could predict the ankle quasi-stiffnesses and work for optimal walking speed with average error of 13% to 30%. We discuss how these models provide a useful framework and foundation for designing subject- and gait-specific prosthetic and exoskeletal devices designed to emulate biological ankle function during level ground walking. PMID:23555839

Memory and learning behaviors mimicked in nanogranular SiO2-based proton conductor gated oxide-based synaptic transistors

NASA Astrophysics Data System (ADS)

Wan, Chang Jin; Zhu, Li Qiang; Zhou, Ju Mei; Shi, Yi; Wan, Qing

2013-10-01

In neuroscience, signal processing, memory and learning function are established in the brain by modifying ionic fluxes in neurons and synapses. Emulation of memory and learning behaviors of biological systems by nanoscale ionic/electronic devices is highly desirable for building neuromorphic systems or even artificial neural networks. Here, novel artificial synapses based on junctionless oxide-based protonic/electronic hybrid transistors gated by nanogranular phosphorus-doped SiO2-based proton-conducting films are fabricated on glass substrates by a room-temperature process. Short-term memory (STM) and long-term memory (LTM) are mimicked by tuning the pulse gate voltage amplitude. The LTM process in such an artificial synapse is due to the proton-related interfacial electrochemical reaction. Our results are highly desirable for building future neuromorphic systems or even artificial networks via electronic elements.In neuroscience, signal processing, memory and learning function are established in the brain by modifying ionic fluxes in neurons and synapses. Emulation of memory and learning behaviors of biological systems by nanoscale ionic/electronic devices is highly desirable for building neuromorphic systems or even artificial neural networks. Here, novel artificial synapses based on junctionless oxide-based protonic/electronic hybrid transistors gated by nanogranular phosphorus-doped SiO2-based proton-conducting films are fabricated on glass substrates by a room-temperature process. Short-term memory (STM) and long-term memory (LTM) are mimicked by tuning the pulse gate voltage amplitude. The LTM process in such an artificial synapse is due to the proton-related interfacial electrochemical reaction. Our results are highly desirable for building future neuromorphic systems or even artificial networks via electronic elements. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr02987e

Boosting flood warning schemes with fast emulator of detailed hydrodynamic models

NASA Astrophysics Data System (ADS)

Bellos, V.; Carbajal, J. P.; Leitao, J. P.

2017-12-01

Floods are among the most destructive catastrophic events and their frequency has incremented over the last decades. To reduce flood impact and risks, flood warning schemes are installed in flood prone areas. Frequently, these schemes are based on numerical models which quickly provide predictions of water levels and other relevant observables. However, the high complexity of flood wave propagation in the real world and the need of accurate predictions in urban environments or in floodplains hinders the use of detailed simulators. This sets the difficulty, we need fast predictions that meet the accuracy requirements. Most physics based detailed simulators although accurate, will not fulfill the speed demand. Even if High Performance Computing techniques are used (the magnitude of required simulation time is minutes/hours). As a consequence, most flood warning schemes are based in coarse ad-hoc approximations that cannot take advantage a detailed hydrodynamic simulation. In this work, we present a methodology for developing a flood warning scheme using an Gaussian Processes based emulator of a detailed hydrodynamic model. The methodology consists of two main stages: 1) offline stage to build the emulator; 2) online stage using the emulator to predict and generate warnings. The offline stage consists of the following steps: a) definition of the critical sites of the area under study, and the specification of the observables to predict at those sites, e.g. water depth, flow velocity, etc.; b) generation of a detailed simulation dataset to train the emulator; c) calibration of the required parameters (if measurements are available). The online stage is carried on using the emulator to predict the relevant observables quickly, and the detailed simulator is used in parallel to verify key predictions of the emulator. The speed gain given by the emulator allows also to quantify uncertainty in predictions using ensemble methods. The above methodology is applied in real world scenario.

Linking big models to big data: efficient ecosystem model calibration through Bayesian model emulation

NASA Astrophysics Data System (ADS)

Fer, I.; Kelly, R.; Andrews, T.; Dietze, M.; Richardson, A. D.

2016-12-01

Our ability to forecast ecosystems is limited by how well we parameterize ecosystem models. Direct measurements for all model parameters are not always possible and inverse estimation of these parameters through Bayesian methods is computationally costly. A solution to computational challenges of Bayesian calibration is to approximate the posterior probability surface using a Gaussian Process that emulates the complex process-based model. Here we report the integration of this method within an ecoinformatics toolbox, Predictive Ecosystem Analyzer (PEcAn), and its application with two ecosystem models: SIPNET and ED2.1. SIPNET is a simple model, allowing application of MCMC methods both to the model itself and to its emulator. We used both approaches to assimilate flux (CO2 and latent heat), soil respiration, and soil carbon data from Bartlett Experimental Forest. This comparison showed that emulator is reliable in terms of convergence to the posterior distribution. A 10000-iteration MCMC analysis with SIPNET itself required more than two orders of magnitude greater computation time than an MCMC run of same length with its emulator. This difference would be greater for a more computationally demanding model. Validation of the emulator-calibrated SIPNET against both the assimilated data and out-of-sample data showed improved fit and reduced uncertainty around model predictions. We next applied the validated emulator method to the ED2, whose complexity precludes standard Bayesian data assimilation. We used the ED2 emulator to assimilate demographic data from a network of inventory plots. For validation of the calibrated ED2, we compared the model to results from Empirical Succession Mapping (ESM), a novel synthesis of successional patterns in Forest Inventory and Analysis data. Our results revealed that while the pre-assimilation ED2 formulation cannot capture the emergent demographic patterns from ESM analysis, constrained model parameters controlling demographic processes increased their agreement considerably.

Estimated Muscle Loads During Squat Exercise in Microgravity Conditions

NASA Technical Reports Server (NTRS)

Fregly, Christopher D.; Kim, Brandon T.; Li, Zhao; DeWitt, John K.; Fregly, Benjamin J.

2012-01-01

Loss of muscle mass in microgravity is one of the primary factors limiting long-term space flight. NASA researchers have developed a number of exercise devices to address this problem. The most recent is the Advanced Resistive Exercise Device (ARED), which is currently used by astronauts on the International Space Station (ISS) to emulate typical free-weight exercises in microgravity. ARED exercise on the ISS is intended to reproduce Earth-level muscle loads, but the actual muscle loads produced remain unknown as they cannot currently be measured directly. In this study we estimated muscle loads experienced during squat exercise on ARED in microgravity conditions representative of Mars, the moon, and the ISS. The estimates were generated using a subject-specific musculoskeletal computer model and ARED exercise data collected on Earth. The results provide insight into the capabilities and limitations of the ARED machine.

A geological history of reflecting optics.

PubMed

Parker, Andrew Richard

2005-03-22

Optical reflectors in animals are diverse and ancient. The first image-forming eye appeared around 543 million years ago. This introduced vision as a selection pressure in the evolution of animals, and consequently the evolution of adapted optical devices. The earliest known optical reflectors--diffraction gratings--are 515 Myr old. The subsequent fossil record preserves multilayer reflectors, including liquid crystals and mirrors, 'white' and 'blue' scattering structures, antireflective surfaces and the very latest addition to optical physics--photonic crystals. The aim of this article is to reveal the diversity of reflecting optics in nature, introducing the first appearance of some reflector types as they appear in the fossil record as it stands (which includes many new records) and backdating others in geological time through evolutionary analyses. This article also reveals the commercial potential for these optical devices, in terms of lessons from their nano-level designs and the possible emulation of their engineering processes--molecular self-assembly.

Establishing a Novel Modeling Tool: A Python-Based Interface for a Neuromorphic Hardware System

PubMed Central

Brüderle, Daniel; Müller, Eric; Davison, Andrew; Muller, Eilif; Schemmel, Johannes; Meier, Karlheinz

2008-01-01

Neuromorphic hardware systems provide new possibilities for the neuroscience modeling community. Due to the intrinsic parallelism of the micro-electronic emulation of neural computation, such models are highly scalable without a loss of speed. However, the communities of software simulator users and neuromorphic engineering in neuroscience are rather disjoint. We present a software concept that provides the possibility to establish such hardware devices as valuable modeling tools. It is based on the integration of the hardware interface into a simulator-independent language which allows for unified experiment descriptions that can be run on various simulation platforms without modification, implying experiment portability and a huge simplification of the quantitative comparison of hardware and simulator results. We introduce an accelerated neuromorphic hardware device and describe the implementation of the proposed concept for this system. An example setup and results acquired by utilizing both the hardware system and a software simulator are demonstrated. PMID:19562085

Establishing a novel modeling tool: a python-based interface for a neuromorphic hardware system.

PubMed

Brüderle, Daniel; Müller, Eric; Davison, Andrew; Muller, Eilif; Schemmel, Johannes; Meier, Karlheinz

2009-01-01

Neuromorphic hardware systems provide new possibilities for the neuroscience modeling community. Due to the intrinsic parallelism of the micro-electronic emulation of neural computation, such models are highly scalable without a loss of speed. However, the communities of software simulator users and neuromorphic engineering in neuroscience are rather disjoint. We present a software concept that provides the possibility to establish such hardware devices as valuable modeling tools. It is based on the integration of the hardware interface into a simulator-independent language which allows for unified experiment descriptions that can be run on various simulation platforms without modification, implying experiment portability and a huge simplification of the quantitative comparison of hardware and simulator results. We introduce an accelerated neuromorphic hardware device and describe the implementation of the proposed concept for this system. An example setup and results acquired by utilizing both the hardware system and a software simulator are demonstrated.

A Comprehensive Study on Energy Efficiency and Performance of Flash-based SSD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Seon-Yeon; Kim, Youngjae; Urgaonkar, Bhuvan

2011-01-01

Use of flash memory as a storage medium is becoming popular in diverse computing environments. However, because of differences in interface, flash memory requires a hard-disk-emulation layer, called FTL (flash translation layer). Although the FTL enables flash memory storages to replace conventional hard disks, it induces significant computational and space overhead. Despite the low power consumption of flash memory, this overhead leads to significant power consumption in an overall storage system. In this paper, we analyze the characteristics of flash-based storage devices from the viewpoint of power consumption and energy efficiency by using various methodologies. First, we utilize simulation tomore » investigate the interior operation of flash-based storage of flash-based storages. Subsequently, we measure the performance and energy efficiency of commodity flash-based SSDs by using microbenchmarks to identify the block-device level characteristics and macrobenchmarks to reveal their filesystem level characteristics.« less

High performance flight computer developed for deep space applications

NASA Technical Reports Server (NTRS)

Bunker, Robert L.

1993-01-01

The development of an advanced space flight computer for real time embedded deep space applications which embodies the lessons learned on Galileo and modern computer technology is described. The requirements are listed and the design implementation that meets those requirements is described. The development of SPACE-16 (Spaceborne Advanced Computing Engine) (where 16 designates the databus width) was initiated to support the MM2 (Marine Mark 2) project. The computer is based on a radiation hardened emulation of a modern 32 bit microprocessor and its family of support devices including a high performance floating point accelerator. Additional custom devices which include a coprocessor to improve input/output capabilities, a memory interface chip, and an additional support chip that provide management of all fault tolerant features, are described. Detailed supporting analyses and rationale which justifies specific design and architectural decisions are provided. The six chip types were designed and fabricated. Testing and evaluation of a brass/board was initiated.

Development of the CELSS Emulator at NASA JSC

NASA Technical Reports Server (NTRS)

Cullingford, Hatice S.

1989-01-01

The Controlled Ecological Life Support System (CELSS) Emulator is under development at the NASA Johnson Space Center (JSC) with the purpose to investigate computer simulations of integrated CELSS operations involving humans, plants, and process machinery. This paper describes Version 1.0 of the CELSS Emulator that was initiated in 1988 on the JSC Multi Purpose Applications Console Test Bed as the simulation framework. The run module of the simulation system now contains a CELSS model called BLSS. The CELSS Emulator makes it possible to generate model data sets, store libraries of results for further analysis, and also display plots of model variables as a function of time. The progress of the project is presented with sample test runs and simulation display pages.

High-emulation mask recognition with high-resolution hyperspectral video capture system

NASA Astrophysics Data System (ADS)

Feng, Jiao; Fang, Xiaojing; Li, Shoufeng; Wang, Yongjin

2014-11-01

We present a method for distinguishing human face from high-emulation mask, which is increasingly used by criminals for activities such as stealing card numbers and passwords on ATM. Traditional facial recognition technique is difficult to detect such camouflaged criminals. In this paper, we use the high-resolution hyperspectral video capture system to detect high-emulation mask. A RGB camera is used for traditional facial recognition. A prism and a gray scale camera are used to capture spectral information of the observed face. Experiments show that mask made of silica gel has different spectral reflectance compared with the human skin. As multispectral image offers additional spectral information about physical characteristics, high-emulation mask can be easily recognized.

Statistical Emulator for Expensive Classification Simulators

NASA Technical Reports Server (NTRS)

Ross, Jerret; Samareh, Jamshid A.

2016-01-01

Expensive simulators prevent any kind of meaningful analysis to be performed on the phenomena they model. To get around this problem the concept of using a statistical emulator as a surrogate representation of the simulator was introduced in the 1980's. Presently, simulators have become more and more complex and as a result running a single example on these simulators is very expensive and can take days to weeks or even months. Many new techniques have been introduced, termed criteria, which sequentially select the next best (most informative to the emulator) point that should be run on the simulator. These criteria methods allow for the creation of an emulator with only a small number of simulator runs. We follow and extend this framework to expensive classification simulators.

Tactile Imaging of an Imbedded Palpable Structure for Breast Cancer Screening

PubMed Central

2015-01-01

Apart from texture, the human finger can sense palpation. The detection of an imbedded structure is a fine balance between the relative stiffness of the matrix, the object, and the device. If the device is too soft, its high responsiveness will limit the depth to which the imbedded structure can be detected. The sensation of palpation is an effective procedure for a physician to examine irregularities. In a clinical breast examination (CBE), by pressing over 1 cm2 area, at a contact pressure in the 70–90 kPa range, the physician feels cancerous lumps that are 8- to 18-fold stiffer than surrounding tissue. Early detection of a lump in the 5–10 mm range leads to an excellent prognosis. We describe a thin-film tactile device that emulates human touch to quantify CBE by imaging the size and shape of 5–10 mm objects at 20 mm depth in a breast model using ∼80 kPa pressure. The linear response of the device allows quantification where the greyscale corresponds to the relative local stiffness. The (background) signal from <2.5-fold stiffer objects at a size below 2 mm is minimal. PMID:25148477

Platelet Glycoprotein lb-1X and Malignancy

DTIC Science & Technology

2010-09-01

supporting the accumulation of more platelets and the elaboration of a fibrin - rich network produced by coagulation factors. This paradigm has been...a platelet - rich thrombus by tethering the platelet to a thrombogenic surface. Several ligands binding to GP Ib-IX have been identified, including...08-1-0576 TITLE: Platelet Glycoprotein lb-1X and Malignancy PRINCIPAL INVESTIGATOR: Dr. Jerry Ware

Multifunctional silk-heparin biomaterials for vascular tissue engineering applications

PubMed Central

Seib, F. Philipp; Herklotz, Manuela; Burke, Kelly A.; Maitz, Manfred F.; Werner, Carsten; Kaplan, David L.

2013-01-01

Over the past 30 years, silk has been proposed for numerous biomedical applications that go beyond its traditional use as a suture material. Silk sutures are well tolerated in humans, but the use of silk for vascular engineering applications still requires extensive biocompatibility testing. Some studies have indicated a need to modify silk to yield a hemocompatible surface. This study examined the potential of low molecular weight heparin as a material for refining silk properties by acting as a carrier for vascular endothelial growth factor (VEGF) and improving silk hemocompatibility. Heparinized silk showed a controlled VEGF release over 6 days; the released VEGF was bioactive and supported the growth of human endothelial cells. Silk samples were then assessed using a humanized hemocompatibility system that employs whole blood and endothelial cells. The overall thrombogenic response for silk was very low and similar to the clinical reference material polytetrafluoroethylene. Despite an initial inflammatory response to silk, apparent as complement and leukocyte activation, the endothelium was maintained in a resting, anticoagulant state. The low thrombogenic response and the ability to control VEGF release support the further development of silk for vascular applications. PMID:24099708

Pharmacological Differentiation of Thrombomodulin Alfa and Activated Protein C on Coagulation and Fibrinolysis In Vitro.

PubMed

Tanaka, Kosuke; Tawara, Shunsuke; Tsuruta, Kazuhisa; Hoppensteadt, Debra; Fareed, Jawed

2018-01-01

Although thrombomodulin alfa (TM alfa), recombinant human soluble thrombomodulin, exerts antithrombogenic effects through activated protein C (APC), clinical trials suggested that TM alfa has a lower bleeding risk than does recombinant human APC. To address the mechanism explaining this difference, effects of TM alfa and APC on thrombogenic, coagulation, and fibrinolytic processes were compared in vitro. TM alfa and APC inhibited generation of thrombogenic markers, thrombin, and prothrombin fragment F1+2 and prolonged coagulation parameters, activated clotting time (ACT), and activated partial thromboplastin time (APTT). Concentrations of TM alfa effective for thrombin and F1+2 generation inhibition were comparable to those of APC. However, effects of TM alfa on ACT and APTT were clearly weaker than those of APC. TM alfa significantly prolonged clot lysis time (CLT) and decreased LY30, a parameter of degree of fibrinolysis in thromboelastography, whereas APC significantly shortened CLT and increased LY30. These results suggested that while the antithrombogenic effects of TM alfa were similar to those of APC, its anticoagulant effects were lower. In addition, effects of TM alfa were antifibrinolytic, while those of APC were profibrinolytic.

Detecting and classifying method based on similarity matching of Android malware behavior with profile.

PubMed

Jang, Jae-Wook; Yun, Jaesung; Mohaisen, Aziz; Woo, Jiyoung; Kim, Huy Kang

2016-01-01

Mass-market mobile security threats have increased recently due to the growth of mobile technologies and the popularity of mobile devices. Accordingly, techniques have been introduced for identifying, classifying, and defending against mobile threats utilizing static, dynamic, on-device, and off-device techniques. Static techniques are easy to evade, while dynamic techniques are expensive. On-device techniques are evasion, while off-device techniques need being always online. To address some of those shortcomings, we introduce Andro-profiler, a hybrid behavior based analysis and classification system for mobile malware. Andro-profiler main goals are efficiency, scalability, and accuracy. For that, Andro-profiler classifies malware by exploiting the behavior profiling extracted from the integrated system logs including system calls. Andro-profiler executes a malicious application on an emulator in order to generate the integrated system logs, and creates human-readable behavior profiles by analyzing the integrated system logs. By comparing the behavior profile of malicious application with representative behavior profile for each malware family using a weighted similarity matching technique, Andro-profiler detects and classifies it into malware families. The experiment results demonstrate that Andro-profiler is scalable, performs well in detecting and classifying malware with accuracy greater than 98 %, outperforms the existing state-of-the-art work, and is capable of identifying 0-day mobile malware samples.

Characterization of crosstalk in stereoscopic display devices.

PubMed

Zafar, Fahad; Badano, Aldo

2014-12-01

Many different types of stereoscopic display devices are used for commercial and research applications. Stereoscopic displays offer the potential to improve performance in detection tasks for medical imaging diagnostic systems. Due to the variety of stereoscopic display technologies, it remains unclear how these compare with each other for detection and estimation tasks. Different stereo devices have different performance trade-offs due to their display characteristics. Among them, crosstalk is known to affect observer perception of 3D content and might affect detection performance. We measured and report the detailed luminance output and crosstalk characteristics for three different types of stereoscopic display devices. We recorded the effect of other issues on recorded luminance profiles such as viewing angle, use of different eye wear, and screen location. Our results show that the crosstalk signature for viewing 3D content can vary considerably when using different types of 3D glasses for active stereo displays. We also show that significant differences are present in crosstalk signatures when varying the viewing angle from 0 degrees to 20 degrees for a stereo mirror 3D display device. Our detailed characterization can help emulate the effect of crosstalk in conducting computational observer image quality assessment evaluations that minimize costly and time-consuming human reader studies.

The Heartmate III: design and in vivo studies of a maglev centrifugal left ventricular assist device.

PubMed

Loree, H M; Bourque, K; Gernes, D B; Richardson, J S; Poirier, V L; Barletta, N; Fleischli, A; Foiera, G; Gempp, T M; Schoeb, R; Litwak, K N; Akimoto, T; Kameneva, M; Watach, M J; Litwak, P

2001-05-01

A compact implantable centrifugal left ventricular assist device (LVAD) (HeartMate III) featuring a magnetically levitated impeller is under development. The goal of our ongoing work is to demonstrate feasibility, low hemolysis, and low thrombogenicity of the titanium pump in chronic bovine in vivo studies. The LVAD is based on so-called bearingless motor technology and combines pump rotor, drive, and magnetic bearing functions in a single unit. The impeller is rotated (theta z) and levitated with both active (X, Y) and passive (Z, theta x, theta y) suspension. Six prototype systems have been built featuring an implantable titanium pump (69 mm diameter, 30 mm height) with textured blood contacting surfaces and extracorporeal electronics. The pumps were implanted in 9 calves (< or = 100 kg at implant) that were anticoagulated with Coumadin (2.5 < or = INR < or = 4.0) throughout the studies. Six studies were electively terminated (at 27-61 days), 1 study was terminated after the development of severe pneumonia and lung atelectasis (at 27 days) another study was terminated after cardiac arrest (at 2 days) while a final study is ongoing (at approximately 100 days). Mean pump flows ranged from 2 to 7 L/min, except for brief periods of exercise at 6 to 9 L/min. Plasma free hemoglobin ranged from 4 to 10 mg/dl. All measured biochemical indicators of end organ function remained within normal range. The pumps have met performance requirements in all 9 implants with acceptable hemolysis and no mechanical failures.

Dynamic emulation modelling for the optimal operation of water systems: an overview

NASA Astrophysics Data System (ADS)

Castelletti, A.; Galelli, S.; Giuliani, M.

2014-12-01

Despite sustained increase in computing power over recent decades, computational limitations remain a major barrier to the effective and systematic use of large-scale, process-based simulation models in rational environmental decision-making. Whereas complex models may provide clear advantages when the goal of the modelling exercise is to enhance our understanding of the natural processes, they introduce problems of model identifiability caused by over-parameterization and suffer from high computational burden when used in management and planning problems. As a result, increasing attention is now being devoted to emulation modelling (or model reduction) as a way of overcoming these limitations. An emulation model, or emulator, is a low-order approximation of the process-based model that can be substituted for it in order to solve high resource-demanding problems. In this talk, an overview of emulation modelling within the context of the optimal operation of water systems will be provided. Particular emphasis will be given to Dynamic Emulation Modelling (DEMo), a special type of model complexity reduction in which the dynamic nature of the original process-based model is preserved, with consequent advantages in a wide range of problems, particularly feedback control problems. This will be contrasted with traditional non-dynamic emulators (e.g. response surface and surrogate models) that have been studied extensively in recent years and are mainly used for planning purposes. A number of real world numerical experiences will be used to support the discussion ranging from multi-outlet water quality control in water reservoir through erosion/sedimentation rebalancing in the operation of run-off-river power plants to salinity control in lake and reservoirs.

UPEML: a machine-portable CDC Update emulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehlhorn, T.A.; Young, M.F.

1984-12-01

UPEML is a machine-portable CDC Update emulation program. UPEML is written in ANSI standard Fortran-77 and is relatively simple and compact. It is capable of emulating a significant subset of the standard CDC Update functions including program library creation and subsequent modification. Machine-portability is an essential attribute of UPEML. It was written primarily to facilitate the use of CDC-based scientific packages on alternate computer systems such as the VAX 11/780 and the IBM 3081.

A Prosthetic Foot Emulator to Optimize Prescription of Prosthetic Feet in Veterans and Service Members with Leg Amputations

DTIC Science & Technology

2017-09-01

AWARD NUMBER: W81XWH-16-1-0569 TITLE: A Prosthetic Foot Emulator to Optimize Prescription of Prosthetic Feet in Veterans and Service Members...Headquarters Services , Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202- 4302...GRANT NUMBER A Prosthetic Foot Emulator to Optimize Prescription of Prosthetic Feet in Veterans and Service Members with Leg Amputations 5c

Satellite Communication Hardware Emulation System (SCHES)

NASA Technical Reports Server (NTRS)

Kaplan, Ted

1993-01-01

Satellite Communication Hardware Emulator System (SCHES) is a powerful simulator that emulates the hardware used in TDRSS links. SCHES is a true bit-by-bit simulator that models communications hardware accurately enough to be used as a verification mechanism for actual hardware tests on user spacecraft. As a credit to its modular design, SCHES is easily configurable to model any user satellite communication link, though some development may be required to tailor existing software to user specific hardware.

Advanced Machine Learning Emulators of Radiative Transfer Models

NASA Astrophysics Data System (ADS)

Camps-Valls, G.; Verrelst, J.; Martino, L.; Vicent, J.

2017-12-01

Physically-based model inversion methodologies are based on physical laws and established cause-effect relationships. A plethora of remote sensing applications rely on the physical inversion of a Radiative Transfer Model (RTM), which lead to physically meaningful bio-geo-physical parameter estimates. The process is however computationally expensive, needs expert knowledge for both the selection of the RTM, its parametrization and the the look-up table generation, as well as its inversion. Mimicking complex codes with statistical nonlinear machine learning algorithms has become the natural alternative very recently. Emulators are statistical constructs able to approximate the RTM, although at a fraction of the computational cost, providing an estimation of uncertainty, and estimations of the gradient or finite integral forms. We review the field and recent advances of emulation of RTMs with machine learning models. We posit Gaussian processes (GPs) as the proper framework to tackle the problem. Furthermore, we introduce an automatic methodology to construct emulators for costly RTMs. The Automatic Gaussian Process Emulator (AGAPE) methodology combines the interpolation capabilities of GPs with the accurate design of an acquisition function that favours sampling in low density regions and flatness of the interpolation function. We illustrate the good capabilities of our emulators in toy examples, leaf and canopy levels PROSPECT and PROSAIL RTMs, and for the construction of an optimal look-up-table for atmospheric correction based on MODTRAN5.

Statistical emulation of landslide-induced tsunamis at the Rockall Bank, NE Atlantic

PubMed Central

Guillas, S.; Georgiopoulou, A.; Dias, F.

2017-01-01

Statistical methods constitute a useful approach to understand and quantify the uncertainty that governs complex tsunami mechanisms. Numerical experiments may often have a high computational cost. This forms a limiting factor for performing uncertainty and sensitivity analyses, where numerous simulations are required. Statistical emulators, as surrogates of these simulators, can provide predictions of the physical process in a much faster and computationally inexpensive way. They can form a prominent solution to explore thousands of scenarios that would be otherwise numerically expensive and difficult to achieve. In this work, we build a statistical emulator of the deterministic codes used to simulate submarine sliding and tsunami generation at the Rockall Bank, NE Atlantic Ocean, in two stages. First we calibrate, against observations of the landslide deposits, the parameters used in the landslide simulations. This calibration is performed under a Bayesian framework using Gaussian Process (GP) emulators to approximate the landslide model, and the discrepancy function between model and observations. Distributions of the calibrated input parameters are obtained as a result of the calibration. In a second step, a GP emulator is built to mimic the coupled landslide-tsunami numerical process. The emulator propagates the uncertainties in the distributions of the calibrated input parameters inferred from the first step to the outputs. As a result, a quantification of the uncertainty of the maximum free surface elevation at specified locations is obtained. PMID:28484339

Uncertainty in modeled upper ocean heat content change

NASA Astrophysics Data System (ADS)

Tokmakian, Robin; Challenor, Peter

2014-02-01

This paper examines the uncertainty in the change in the heat content in the ocean component of a general circulation model. We describe the design and implementation of our statistical methodology. Using an ensemble of model runs and an emulator, we produce an estimate of the full probability distribution function (PDF) for the change in upper ocean heat in an Atmosphere/Ocean General Circulation Model, the Community Climate System Model v. 3, across a multi-dimensional input space. We show how the emulator of the GCM's heat content change and hence, the PDF, can be validated and how implausible outcomes from the emulator can be identified when compared to observational estimates of the metric. In addition, the paper describes how the emulator outcomes and related uncertainty information might inform estimates of the same metric from a multi-model Coupled Model Intercomparison Project phase 3 ensemble. We illustrate how to (1) construct an ensemble based on experiment design methods, (2) construct and evaluate an emulator for a particular metric of a complex model, (3) validate the emulator using observational estimates and explore the input space with respect to implausible outcomes and (4) contribute to the understanding of uncertainties within a multi-model ensemble. Finally, we estimate the most likely value for heat content change and its uncertainty for the model, with respect to both observations and the uncertainty in the value for the input parameters.

Statistical emulation of landslide-induced tsunamis at the Rockall Bank, NE Atlantic.

PubMed

Salmanidou, D M; Guillas, S; Georgiopoulou, A; Dias, F

2017-04-01

Statistical methods constitute a useful approach to understand and quantify the uncertainty that governs complex tsunami mechanisms. Numerical experiments may often have a high computational cost. This forms a limiting factor for performing uncertainty and sensitivity analyses, where numerous simulations are required. Statistical emulators, as surrogates of these simulators, can provide predictions of the physical process in a much faster and computationally inexpensive way. They can form a prominent solution to explore thousands of scenarios that would be otherwise numerically expensive and difficult to achieve. In this work, we build a statistical emulator of the deterministic codes used to simulate submarine sliding and tsunami generation at the Rockall Bank, NE Atlantic Ocean, in two stages. First we calibrate, against observations of the landslide deposits, the parameters used in the landslide simulations. This calibration is performed under a Bayesian framework using Gaussian Process (GP) emulators to approximate the landslide model, and the discrepancy function between model and observations. Distributions of the calibrated input parameters are obtained as a result of the calibration. In a second step, a GP emulator is built to mimic the coupled landslide-tsunami numerical process. The emulator propagates the uncertainties in the distributions of the calibrated input parameters inferred from the first step to the outputs. As a result, a quantification of the uncertainty of the maximum free surface elevation at specified locations is obtained.

Entangling spin-spin interactions of ions in individually controlled potential wells

NASA Astrophysics Data System (ADS)

Wilson, Andrew; Colombe, Yves; Brown, Kenton; Knill, Emanuel; Leibfried, Dietrich; Wineland, David

2014-03-01

Physical systems that cannot be modeled with classical computers appear in many different branches of science, including condensed-matter physics, statistical mechanics, high-energy physics, atomic physics and quantum chemistry. Despite impressive progress on the control and manipulation of various quantum systems, implementation of scalable devices for quantum simulation remains a formidable challenge. As one approach to scalability in simulation, here we demonstrate an elementary building-block of a configurable quantum simulator based on atomic ions. Two ions are trapped in separate potential wells that can individually be tailored to emulate a number of different spin-spin couplings mediated by the ions' Coulomb interaction together with classical laser and microwave fields. We demonstrate deterministic tuning of this interaction by independent control of the local wells and emulate a particular spin-spin interaction to entangle the internal states of the two ions with 0.81(2) fidelity. Extension of the building-block demonstrated here to a 2D-network, which ion-trap micro-fabrication processes enable, may provide a new quantum simulator architecture with broad flexibility in designing and scaling the arrangement of ions and their mutual interactions. This research was funded by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA), ONR, and the NIST Quantum Information Program.

Bulk unipolar diodes formed in GaAs by ion implantation

NASA Astrophysics Data System (ADS)

Hutchinson, S.; Kelly, M. J.; Gwilliam, R.; Sealy, B. J.; Carr, M.

1999-01-01

In an attempt to emulate epitaxially manufactured semiconductor multilayers for microwave device applications, we have produced a camel diode structure in GaAs for the first time, using the tail of a Mg + implant into a molecular beam epitaxially grown n +-n --n + structure. Using a range of ion energies and doses, samples are observed to exhibit bulk unipolar diode characteristics. With low dose and energy, a diode with barrier height of ˜0.8 V and ideality factor ˜1.25 is achieved. 'Punch through' diode characteristics are obtained at high ion dose and energy, some with knee voltages in excess of 7 V.

Nanoelectronic programmable synapses based on phase change materials for brain-inspired computing.

PubMed

Kuzum, Duygu; Jeyasingh, Rakesh G D; Lee, Byoungil; Wong, H-S Philip

2012-05-09

Brain-inspired computing is an emerging field, which aims to extend the capabilities of information technology beyond digital logic. A compact nanoscale device, emulating biological synapses, is needed as the building block for brain-like computational systems. Here, we report a new nanoscale electronic synapse based on technologically mature phase change materials employed in optical data storage and nonvolatile memory applications. We utilize continuous resistance transitions in phase change materials to mimic the analog nature of biological synapses, enabling the implementation of a synaptic learning rule. We demonstrate different forms of spike-timing-dependent plasticity using the same nanoscale synapse with picojoule level energy consumption.

ProjectQ: Compiling quantum programs for various backends

NASA Astrophysics Data System (ADS)

Haener, Thomas; Steiger, Damian S.; Troyer, Matthias

In order to control quantum computers beyond the current generation, a high level quantum programming language and optimizing compilers will be essential. Therefore, we have developed ProjectQ - an open source software framework to facilitate implementing and running quantum algorithms both in software and on actual quantum hardware. Here, we introduce the backends available in ProjectQ. This includes a high-performance simulator and emulator to test and debug quantum algorithms, tools for resource estimation, and interfaces to several small-scale quantum devices. We demonstrate the workings of the framework and show how easily it can be further extended to control upcoming quantum hardware.

DHCAL with minimal absorber: measurements with positrons

NASA Astrophysics Data System (ADS)

Freund, B.; Neubüser, C.; Repond, J.; Schlereth, J.; Xia, L.; Dotti, A.; Grefe, C.; Ivantchenko, V.; Berenguer Antequera, J.; Calvo Alamillo, E.; Fouz, M.-C.; Marin, J.; Puerta-Pelayo, J.; Verdugo, A.; Brianne, E.; Ebrahimi, A.; Gadow, K.; Göttlicher, P.; Günter, C.; Hartbrich, O.; Hermberg, B.; Irles, A.; Krivan, F.; Krüger, K.; Kvasnicka, J.; Lu, S.; Lutz, B.; Morgunov, V.; Provenza, A.; Reinecke, M.; Sefkow, F.; Schuwalow, S.; Tran, H. L.; Garutti, E.; Laurien, S.; Matysek, M.; Ramilli, M.; Schroeder, S.; Bilki, B.; Norbeck, E.; Northacker, D.; Onel, Y.; Cvach, J.; Gallus, P.; Havranek, M.; Janata, M.; Kovalcuk, M.; Kvasnicka, J.; Lednicky, D.; Marcisovsky, M.; Polak, I.; Popule, J.; Tomasek, L.; Tomasek, M.; Sicho, P.; Smolik, J.; Vrba, V.; Zalesak, J.; van Doren, B.; Wilson, G. W.; Kawagoe, K.; Hirai, H.; Sudo, Y.; Suehara, T.; Sumida, H.; Takada, S.; Tomita, T.; Yoshioka, T.; Bilokin, S.; Bonis, J.; Cornebise, P.; Pöschl, R.; Richard, F.; Thiebault, A.; Zerwas, D.; Hostachy, J.-Y.; Morin, L.; Besson, D.; Chadeeva, M.; Danilov, M.; Markin, O.; Popova, E.; Gabriel, M.; Goecke, P.; Kiesling, C.; van der Kolk, N.; Simon, F.; Szalay, M.; Corriveau, F.; Blazey, G. C.; Dyshkant, A.; Francis, K.; Zutshi, V.; Kotera, K.; Ono, H.; Takeshita, T.; Ieki, S.; Kamiya, Y.; Ootani, W.; Shibata, N.; Jeans, D.; Komamiya, S.; Nakanishi, H.

2016-05-01

In special tests, the active layers of the CALICE Digital Hadron Calorimeter prototype, the DHCAL, were exposed to low energy particle beams, without being interleaved by absorber plates. The thickness of each layer corresponded approximately to 0.29 radiation lengths or 0.034 nuclear interaction lengths, defined mostly by the copper and steel skins of the detector cassettes. This paper reports on measurements performed with this device in the Fermilab test beam with positrons in the energy range of 1 to 10 GeV. The measurements are compared to simulations based on GEANT4 and a standalone program to emulate the detailed response of the active elements.

A floating-point/multiple-precision processor for airborne applications

NASA Technical Reports Server (NTRS)

Yee, R.

1982-01-01

A compact input output (I/O) numerical processor capable of performing floating-point, multiple precision and other arithmetic functions at execution times which are at least 100 times faster than comparable software emulation is described. The I/O device is a microcomputer system containing a 16 bit microprocessor, a numerical coprocessor with eight 80 bit registers running at a 5 MHz clock rate, 18K random access memory (RAM) and 16K electrically programmable read only memory (EPROM). The processor acts as an intelligent slave to the host computer and can be programmed in high order languages such as FORTRAN and PL/M-86.

Emulation applied to reliability analysis of reconfigurable, highly reliable, fault-tolerant computing systems

NASA Technical Reports Server (NTRS)

Migneault, G. E.

1979-01-01

Emulation techniques applied to the analysis of the reliability of highly reliable computer systems for future commercial aircraft are described. The lack of credible precision in reliability estimates obtained by analytical modeling techniques is first established. The difficulty is shown to be an unavoidable consequence of: (1) a high reliability requirement so demanding as to make system evaluation by use testing infeasible; (2) a complex system design technique, fault tolerance; (3) system reliability dominated by errors due to flaws in the system definition; and (4) elaborate analytical modeling techniques whose precision outputs are quite sensitive to errors of approximation in their input data. Next, the technique of emulation is described, indicating how its input is a simple description of the logical structure of a system and its output is the consequent behavior. Use of emulation techniques is discussed for pseudo-testing systems to evaluate bounds on the parameter values needed for the analytical techniques. Finally an illustrative example is presented to demonstrate from actual use the promise of the proposed application of emulation.

Space-Shuttle Emulator Software

NASA Technical Reports Server (NTRS)

Arnold, Scott; Askew, Bill; Barry, Matthew R.; Leigh, Agnes; Mermelstein, Scott; Owens, James; Payne, Dan; Pemble, Jim; Sollinger, John; Thompson, Hiram;

Internal passivation of Al-based microchannel devices by electrochemical anodization

NASA Astrophysics Data System (ADS)

Hymel, Paul J.; Guan, D. S.; Mu, Yang; Meng, W. J.; Meng, Andrew C.

2015-02-01

Metal-based microchannel devices have wide-ranging applications. We report here a method to electrochemically anodize the internal surfaces of Al microchannels, with the purpose of forming a uniform and dense anodic aluminum oxide (AAO) layer on microchannel internal surfaces for chemical passivation and corrosion resistance. A pulsed electrolyte flow was utilized to emulate conventional anodization processes while replenishing depleted ionic species within Al microtubes and microchannels. After anodization, the AAO film was sealed in hot water to close the nanopores. Focused ion beam (FIB) sectioning, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were utilized to characterize the AAO morphology and composition. Potentiodynamic polarization corrosion testing of anodized Al microtube half-sections in a NaCl solution showed an order of magnitude decrease in anodic corrosion current when compared to an unanodized tube. The surface passivation process was repeated for Al-based microchannel heat exchangers. A corrosion testing method based on the anodization process showed higher resistance to ion transport through the anodized specimens than unanodized specimens, thus verifying the internal anodization and sealing process as a viable method for surface passivation of Al microchannel devices.

Knowing for Nursing Practice: Patterns of Knowledge and Their Emulation in Expert Systems

PubMed Central

Abraham, Ivo L.; Fitzpatrick, Joyce J.

1987-01-01

This paper addresses the issue of clinical knowledge in nursing, and the feasibility of emulating this knowledge into expert system technology. The perspective on patterns of knowing for nursing practice, advanced by Carper (1978), serves as point of departure. The four patterns of knowing -- empirics, esthetics, ethics, personal knowledge -- are evaluated as to the extent to which they can be emulated in clinical expert systems, given constraints imposed by the current technology of these systems.

Fatty acid and cholesterol profiles and hypocholesterolemic, atherogenic, and thrombogenic indices of table eggs in the retail market.

PubMed

Attia, Youssef A; Al-Harthi, Mohammed A; Korish, Mohamed A; Shiboob, Mohamed M

2015-10-27

Eggs are an important source of food due to its favorable effects on human health derived from the protein, fats, minerals, vitamins and bioactive components. We studied the effects of source of eggs in the retail market on fatty acids, lipid profiles and antioxidant status in eggs. Eggs from four sources named A, B, C, and D in the retail market were collected to determine fatty acid, total lipid, and cholesterol profiles; hypocholesterolemic, atherogenic and thrombotic indices; antioxidant status (e.g., of malondialdehyde); and total antioxidant capacity in the whole edible parts of eggs (albumen + yolk) and egg yolk. Samples were collected four times and pooled over times to represent 5 and 10 samples per source for determinations of fatty acids and determinations of lipid profiles and antioxidant status, respectively. Fatty acid, total lipid, and cholesterol profiles; hypocholesterolemic, atherogenic and thrombotic indices; presence of malondialdehyde; and total antioxidant capacity in the whole edible parts of eggs and egg yolk showed significant differences (P ≥ 0.05) among different sources of eggs in retail market. Source D showed higher levels of saturated fatty acids (SFA) and linoleic and monounsaturated fatty acid (MUFA)/polyunsaturated fatty acid (PUFA) ratio but lower levels of MUFA and linolenic, arachidonic, eicosapentaeonic (EPA), decohexaenoic (DHA), and total ω9 fatty acids and lower unsaturated fatty acids (UFA)/SFA ratio. Similar trend was shown in fatty acids profiles of the whole edible parts of eggs. On the other hand, total cholesterol, low density lipoprotein (LDL), LDL/high density lipoprotein (HDL) ratio, and atherogenic and thrombogenic indices and total antioxidant capacity of source D were significantly higher than those of other source, but levels of hypocholesterolemic index, and malondialdehyde levels were lower for source D. Eggs in the retail market in Jeddah city, Saudi Arabia, from May to August 2015 showed a different pattern of fatty acid and cholesterol profiles; hypocholesterolemic, atherogenic, and thrombogenic indices; and antioxidant status, which might reflect the nutritional and husbandry practice of laying hens. This can affect the nutritional values of eggs, and hence, customer benefits, suggesting the need for standardization and quality control based on nutrient index values.

Determinants of blood levels of some thrombogenic biomarkers in healthy Arab adolescent subjects.

PubMed

Akanji, Abayomi O; Al-Isa, Abdulwahab N; Thalib, Lukman

2011-10-01

Acute coronary syndromes present clinically as a consequence of plaque rupture and thrombosis possibly related to altered homeostasis of thrombogenic factors. It is speculated that this vulnerability in adults should be predictable from blood levels of thrombogenic biomarkers in children and adolescents. This study aims to examine the determinants and blood levels of lipoprotein(a) [Lp(a)], fibrinogen (FBG) and plasminogen activator inhibitor-1 (PAI-1) in healthy adolescents stratified according to age group, gender and body mass. A total of 774 (316 males 458 females) healthy adolescent Arab subjects aged 10-19 years and attending secondary schools in Kuwait were interviewed by a validated questionnaire for variables relating to socio-demographic variables, diet and physical activity. They also had anthropometry, BP measurement and determination of fasting blood levels of Lp(a), low density lipoprotein (LDL)-cholesterol, apolipoprotein (apo) B, PAI-1 activity and FBG. The median (interquartile range, IQR) plasma levels of PAI-1 activity, FBG, Lp(a) and apoB were respectively 1.59 (0.58-3.78) U/mL, 296 (190-417) mg/dL, 10.0 (4.8-21.0) mg/dL and 0.72 (0.60-0.85) g/L. Boys had significantly higher PAI-1, FBG and apoB concentrations than the girls, although Lp(a) levels were greater in the latter. The overweight and obese subjects tended to have higher levels of LDL, apoB, FBG and PAI-1 but not Lp(a). Furthermore, the younger adolescent males and females (age <14 years) consistently had higher FBG levels than the older ones (age >14 years). Lp(a) and PAI-1 levels did not appear significantly influenced by this age stratification. Bivariate and multivariate analyses with adjustment for putative body mass index (BMI) confounders indicated that the independent determinants of these biomarkers were (i) Lp(a): apoB, gender; (ii) PAI-1: BMI, apoB, diet; (iii) FBG: BMI, gender, age, family income; and (iv) apoB: BMI, gender and PAI-1. The blood levels of the prothrombotic biomarkers ;ibLp(a), PAI-1, and FBG;ic in healthy Kuwaiti adolescent subjects are variably influenced by age, gender, body mass and socio-demographic factors.

Effect of electric charge on the adhesion of human blood platelets.

PubMed

Lowkis, B; Szymonowicz, M

1993-01-01

The paper presents the results of research into the effect of the size and depth of the implanted electric charge on the adhesion of human blood platelets. The experiments were carried out on polyethylene terephthalate PET foil of 36 microns thickness. The electret formation process was carried out in an electron-beam device. The electrization conditions were such that electrets with the excess electric charge accumulated at various depths were obtained. The selection of conditions was verified by investigating the space charge distribution with the use of the virtual electrode method. The microscopic observation of non-electrified foils and electrets as well as the quantitative examination of the adhesion of human blood platelets has explicitly confirmed the positive influence of the electret effect on the thrombogenesis of PET foil. This made it possible to define the optimum electrization conditions. The research has additionally indicated that the relationship between the amount of adherent blood platelets and the size of the electric charge is not a simple relation of the kind: the larger negative charge, the more thrombogenic material. The decisive and positive effect of the space charge has been confirmed by analysing the effectiveness of the surface and space charge.

High fidelity wireless network evaluation for heterogeneous cognitive radio networks

NASA Astrophysics Data System (ADS)

Ding, Lei; Sagduyu, Yalin; Yackoski, Justin; Azimi-Sadjadi, Babak; Li, Jason; Levy, Renato; Melodia, Tammaso

2012-06-01

We present a high fidelity cognitive radio (CR) network emulation platform for wireless system tests, measure- ments, and validation. This versatile platform provides the configurable functionalities to control and repeat realistic physical channel effects in integrated space, air, and ground networks. We combine the advantages of scalable simulation environment with reliable hardware performance for high fidelity and repeatable evaluation of heterogeneous CR networks. This approach extends CR design only at device (software-defined-radio) or lower-level protocol (dynamic spectrum access) level to end-to-end cognitive networking, and facilitates low-cost deployment, development, and experimentation of new wireless network protocols and applications on frequency- agile programmable radios. Going beyond the channel emulator paradigm for point-to-point communications, we can support simultaneous transmissions by network-level emulation that allows realistic physical-layer inter- actions between diverse user classes, including secondary users, primary users, and adversarial jammers in CR networks. In particular, we can replay field tests in a lab environment with real radios perceiving and learning the dynamic environment thereby adapting for end-to-end goals over distributed spectrum coordination channels that replace the common control channel as a single point of failure. CR networks offer several dimensions of tunable actions including channel, power, rate, and route selection. The proposed network evaluation platform is fully programmable and can reliably evaluate the necessary cross-layer design solutions with configurable op- timization space by leveraging the hardware experiments to represent the realistic effects of physical channel, topology, mobility, and jamming on spectrum agility, situational awareness, and network resiliency. We also provide the flexibility to scale up the test environment by introducing virtual radios and establishing seamless signal-level interactions with real radios. This holistic wireless evaluation approach supports a large-scale, het- erogeneous, and dynamic CR network architecture and allows developing cross-layer network protocols under high fidelity, repeatable, and scalable wireless test scenarios suitable for heterogeneous space, air, and ground networks.

Corpuls cpr resuscitation device generates superior emulated flows and pressures than LUCAS II in a mechanical thorax model.

PubMed

Eichhorn, S; Mendoza Garcia, A; Polski, M; Spindler, J; Stroh, A; Heller, M; Lange, R; Krane, M

2017-06-01

The provision of sufficient chest compression is among the most important factors influencing patient survival during cardiopulmonary resuscitation (CPR). One approach to optimize the quality of chest compressions is to use mechanical-resuscitation devices. The aim of this study was to compare a new device for chest compression (corpuls cpr) with an established device (LUCAS II). We used a mechanical thorax model consisting of a chest with variable stiffness and an integrated heart chamber which generated blood flow dependent on the compression depth and waveform. The method of blood-flow generation could be changed between direct cardiac-compression mode and thoracic-pump mode. Different chest-stiffness settings and compression modes were tested to generate various blood-flow profiles. Additionally, an endurance test at high stiffness was performed to measure overall performance and compression consistency. Both resuscitation machines were able to compress the model thorax with a frequency of 100/min and a depth of 5 cm, independent of the chosen chest stiffness. Both devices passed the endurance test without difficulty. The corpuls cpr device was able to generate about 10-40% more blood flow than the LUCAS II device, depending on the model settings. In most scenarios, the corpuls cpr device also generated a higher blood pressure than the LUCAS II. The peak compression forces during CPR were about 30% higher using the corpuls cpr device than with the LUCAS II. In this study, the corpuls cpr device had improved blood flow and pressure outcomes than the LUCAS II device. Further examination in an animal model is required to prove the findings of this preliminary study.

Dynamic climate emulators for solar geoengineering

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacMartin, Douglas G.; Kravitz, Ben

2016-12-22

Climate emulators trained on existing simulations can be used to project project the climate effects that result from different possible future pathways of anthropogenic forcing, without further relying on general circulation model (GCM) simulations. We extend this idea to include different amounts of solar geoengineering in addition to different pathways of greenhouse gas concentrations, by training emulators from a multi-model ensemble of simulations from the Geoengineering Model Intercomparison Project (GeoMIP). The emulator is trained on the abrupt 4 × CO 2 and a compensating solar reduction simulation (G1), and evaluated by comparing predictions against a simulated 1 % per yearmore » CO 2 increase and a similarly smaller solar reduction (G2). We find reasonable agreement in most models for predicting changes in temperature and precipitation (including regional effects), and annual-mean Northern Hemisphere sea ice extent, with the difference between simulation and prediction typically being smaller than natural variability. This verifies that the linearity assumption used in constructing the emulator is sufficient for these variables over the range of forcing considered. Annual-minimum Northern Hemisphere sea ice extent is less well predicted, indicating a limit to the linearity assumption.« less

Panel Flutter Emulation Using a Few Concentrated Forces

NASA Astrophysics Data System (ADS)

Dhital, Kailash; Han, Jae-Hung

2018-04-01

The objective of this paper is to study the feasibility of panel flutter emulation using a few concentrated forces. The concentrated forces are considered to be equivalent to aerodynamic forces. The equivalence is carried out using surface spline method and principle of virtual work. The structural modeling of the plate is based on the classical plate theory and the aerodynamic modeling is based on the piston theory. The present approach differs from the linear panel flutter analysis in scheming the modal aerodynamics forces with unchanged structural properties. The solutions for the flutter problem are obtained numerically using the standard eigenvalue procedure. A few concentrated forces were considered with an optimization effort to decide their optimal locations. The optimization process is based on minimizing the error between the flutter bounds from emulated and linear flutter analysis method. The emulated flutter results for the square plate of four different boundary conditions using six concentrated forces are obtained with minimal error to the reference value. The results demonstrated the workability and viability of using concentrated forces in emulating real panel flutter. In addition, the paper includes the parametric studies of linear panel flutter whose proper literatures are not available.

The Mira-Titan Universe. II. Matter Power Spectrum Emulation

NASA Astrophysics Data System (ADS)

Lawrence, Earl; Heitmann, Katrin; Kwan, Juliana; Upadhye, Amol; Bingham, Derek; Habib, Salman; Higdon, David; Pope, Adrian; Finkel, Hal; Frontiere, Nicholas

2017-09-01

We introduce a new cosmic emulator for the matter power spectrum covering eight cosmological parameters. Targeted at optical surveys, the emulator provides accurate predictions out to a wavenumber k˜ 5 Mpc-1 and redshift z≤slant 2. In addition to covering the standard set of ΛCDM parameters, massive neutrinos and a dynamical dark energy of state are included. The emulator is built on a sample set of 36 cosmological models, carefully chosen to provide accurate predictions over the wide and large parameter space. For each model, we have performed a high-resolution simulation, augmented with 16 medium-resolution simulations and TimeRG perturbation theory results to provide accurate coverage over a wide k-range; the data set generated as part of this project is more than 1.2Pbytes. With the current set of simulated models, we achieve an accuracy of approximately 4%. Because the sampling approach used here has established convergence and error-control properties, follow-up results with more than a hundred cosmological models will soon achieve ˜ 1 % accuracy. We compare our approach with other prediction schemes that are based on halo model ideas and remapping approaches. The new emulator code is publicly available.

Low-warming Scenarios and their Approximation: Testing Emulation Performance for Average and Extreme Variables

NASA Astrophysics Data System (ADS)

Tebaldi, C.; Knutti, R.; Armbruster, A.

2017-12-01

Taking advantage of the availability of ensemble simulations under low-warming scenarios performed with NCAR-DOE CESM, we test the performance of established methods for climate model output emulation. The goal is to provide a green, yellow or red light to the large impact research community that may be interested in performing impact analysis using climate model output other than, or in conjunction with, CESM's, especially as the IPCC Special Report on the 1.5 target urgently calls for scientific contributions exploring the costs and benefits of attaining these ambitious goals. We test the performance of emulators of average temperature and precipitation - and their interannual variability - and we also explore the possibility of emulating indices of extremes (ETCCDI indices), devised to offer impact relevant information from daily output of temperature and precipitation. Different degrees of departure from the linearity assumed in these traditional emulation approaches are found across the various quantities considered, and across regions, highlighting different degrees of quality in the approximations, and therefore some challenges in the provision of climate change information for impact analysis under these new scenarios that not many models have thus far targeted through their simulations.

The Mira-Titan Universe. II. Matter Power Spectrum Emulation

DOE PAGES

Lawrence, Earl; Heitmann, Katrin; Kwan, Juliana; ...

2017-09-20

We introduce a new cosmic emulator for the matter power spectrum covering eight cosmological parameters. Targeted at optical surveys, the emulator provides accurate predictions out to a wavenumber k ~ 5Mpc -1 and redshift z ≤ 2. Besides covering the standard set of CDM parameters, massive neutrinos and a dynamical dark energy of state are included. The emulator is built on a sample set of 36 cosmological models, carefully chosen to provide accurate predictions over the wide and large parameter space. For each model, we have performed a high-resolution simulation, augmented with sixteen medium-resolution simulations and TimeRG perturbation theory resultsmore » to provide accurate coverage of a wide k-range; the dataset generated as part of this project is more than 1.2Pbyte. With the current set of simulated models, we achieve an accuracy of approximately 4%. Because the sampling approach used here has established convergence and error-control properties, follow-on results with more than a hundred cosmological models will soon achieve ~1% accuracy. We compare our approach with other prediction schemes that are based on halo model ideas and remapping approaches. The new emulator code is publicly available.« less

The Mira-Titan Universe. II. Matter Power Spectrum Emulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lawrence, Earl; Heitmann, Katrin; Kwan, Juliana

We introduce a new cosmic emulator for the matter power spectrum covering eight cosmological parameters. Targeted at optical surveys, the emulator provides accurate predictions out to a wavenumber k ~ 5Mpc -1 and redshift z ≤ 2. Besides covering the standard set of CDM parameters, massive neutrinos and a dynamical dark energy of state are included. The emulator is built on a sample set of 36 cosmological models, carefully chosen to provide accurate predictions over the wide and large parameter space. For each model, we have performed a high-resolution simulation, augmented with sixteen medium-resolution simulations and TimeRG perturbation theory resultsmore » to provide accurate coverage of a wide k-range; the dataset generated as part of this project is more than 1.2Pbyte. With the current set of simulated models, we achieve an accuracy of approximately 4%. Because the sampling approach used here has established convergence and error-control properties, follow-on results with more than a hundred cosmological models will soon achieve ~1% accuracy. We compare our approach with other prediction schemes that are based on halo model ideas and remapping approaches. The new emulator code is publicly available.« less

User-Friendly Interface Developed for a Web-Based Service for SpaceCAL Emulations

NASA Technical Reports Server (NTRS)

Liszka, Kathy J.; Holtz, Allen P.

2004-01-01

A team at the NASA Glenn Research Center is developing a Space Communications Architecture Laboratory (SpaceCAL) for protocol development activities for coordinated satellite missions. SpaceCAL will provide a multiuser, distributed system to emulate space-based Internet architectures, backbone networks, formation clusters, and constellations. As part of a new effort in 2003, building blocks are being defined for an open distributed system to make the satellite emulation test bed accessible through an Internet connection. The first step in creating a Web-based service to control the emulation remotely is providing a user-friendly interface for encoding the data into a well-formed and complete Extensible Markup Language (XML) document. XML provides coding that allows data to be transferred between dissimilar systems. Scenario specifications include control parameters, network routes, interface bandwidths, delay, and bit error rate. Specifications for all satellite, instruments, and ground stations in a given scenario are also included in the XML document. For the SpaceCAL emulation, the XML document can be created using XForms, a Webbased forms language for data collection. Contrary to older forms technology, the interactive user interface makes the science prevalent, not the data representation. Required versus optional input fields, default values, automatic calculations, data validation, and reuse will help researchers quickly and accurately define missions. XForms can apply any XML schema defined for the test mission to validate data before forwarding it to the emulation facility. New instrument definitions, facilities, and mission types can be added to the existing schema. The first prototype user interface incorporates components for interactive input and form processing. Internet address, data rate, and the location of the facility are implemented with basic form controls with default values provided for convenience and efficiency using basic XForms operations. Because different emulation scenarios will vary widely in their component structure, more complex operations are used to add and delete facilities.

The TAVERNS emulator: An Ada simulation of the space station data communications network and software development environment

NASA Technical Reports Server (NTRS)

Howes, Norman R.

1986-01-01

The Space Station DMS (Data Management System) is the onboard component of the Space Station Information System (SSIS) that includes the computers, networks and software that support the various core and payload subsystems of the Space Station. TAVERNS (Test And Validation Environment for Remote Networked Systems) is a distributed approach for development and validation of application software for Space Station. The TAVERNS concept assumes that the different subsystems will be developed by different contractors who may be geographically separated. The TAVERNS Emulator is an Ada simulation of a TAVERNS on the ASD VAX. The software services described in the DMS Test Bed User's Manual are being emulated on the VAX together with simulations of some of the core subsystems and a simulation of the DCN. The TAVERNS Emulator will be accessible remotely from any VAX that can communicate with the ASD VAX.

The application of emulation techniques in the analysis of highly reliable, guidance and control computer systems

NASA Technical Reports Server (NTRS)

Migneault, Gerard E.

1987-01-01

Emulation techniques can be a solution to a difficulty that arises in the analysis of the reliability of guidance and control computer systems for future commercial aircraft. Described here is the difficulty, the lack of credibility of reliability estimates obtained by analytical modeling techniques. The difficulty is an unavoidable consequence of the following: (1) a reliability requirement so demanding as to make system evaluation by use testing infeasible; (2) a complex system design technique, fault tolerance; (3) system reliability dominated by errors due to flaws in the system definition; and (4) elaborate analytical modeling techniques whose precision outputs are quite sensitive to errors of approximation in their input data. Use of emulation techniques for pseudo-testing systems to evaluate bounds on the parameter values needed for the analytical techniques is then discussed. Finally several examples of the application of emulation techniques are described.

Fast emulation of track reconstruction in the CMS simulation

NASA Astrophysics Data System (ADS)

Komm, Matthias; CMS Collaboration

2017-10-01

Simulated samples of various physics processes are a key ingredient within analyses to unlock the physics behind LHC collision data. Samples with more and more statistics are required to keep up with the increasing amounts of recorded data. During sample generation, significant computing time is spent on the reconstruction of charged particle tracks from energy deposits which additionally scales with the pileup conditions. In CMS, the FastSimulation package is developed for providing a fast alternative to the standard simulation and reconstruction workflow. It employs various techniques to emulate track reconstruction effects in particle collision events. Several analysis groups in CMS are utilizing the package, in particular those requiring many samples to scan the parameter space of physics models (e.g. SUSY) or for the purpose of estimating systematic uncertainties. The strategies for and recent developments in this emulation are presented, including a novel, flexible implementation of tracking emulation while retaining a sufficient, tuneable accuracy.

Flash LIDAR Emulator for HIL Simulation

NASA Technical Reports Server (NTRS)

Brewster, Paul F.

2010-01-01

NASA's Autonomous Landing and Hazard Avoidance Technology (ALHAT) project is building a system for detecting hazards and automatically landing controlled vehicles safely anywhere on the Moon. The Flash Light Detection And Ranging (LIDAR) sensor is used to create on-the-fly a 3D map of the unknown terrain for hazard detection. As part of the ALHAT project, a hardware-in-the-loop (HIL) simulation testbed was developed to test the data processing, guidance, and navigation algorithms in real-time to prove their feasibility for flight. Replacing the Flash LIDAR camera with an emulator in the testbed provided a cheaper, safer, more feasible way to test the algorithms in a controlled environment. This emulator must have the same hardware interfaces as the LIDAR camera, have the same performance characteristics, and produce images similar in quality to the camera. This presentation describes the issues involved and the techniques used to create a real-time flash LIDAR emulator to support HIL simulation.

Performance Guaranteed Inertia Emulation forDiesel-Wind System Feed Microgrid via ModelReference Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Melin, Alexander M.; Zhang, Yichen; Djouadi, Seddik

In this paper, a model reference control based inertia emulation strategy is proposed. Desired inertia can be precisely emulated through this control strategy so that guaranteed performance is ensured. A typical frequency response model with parametrical inertia is set to be the reference model. A measurement at a specific location delivers the information of disturbance acting on the diesel-wind system to the referencemodel. The objective is for the speed of the diesel-wind system to track the reference model. Since active power variation is dominantly governed by mechanical dynamics and modes, only mechanical dynamics and states, i.e., a swing-engine-governor system plusmore » a reduced-order wind turbine generator, are involved in the feedback control design. The controller is implemented in a three-phase diesel-wind system feed microgrid. The results show exact synthetic inertia is emulated, leading to guaranteed performance and safety bounds.« less

A reconfigurable on-line learning spiking neuromorphic processor comprising 256 neurons and 128K synapses.

PubMed

Qiao, Ning; Mostafa, Hesham; Corradi, Federico; Osswald, Marc; Stefanini, Fabio; Sumislawska, Dora; Indiveri, Giacomo

2015-01-01

Implementing compact, low-power artificial neural processing systems with real-time on-line learning abilities is still an open challenge. In this paper we present a full-custom mixed-signal VLSI device with neuromorphic learning circuits that emulate the biophysics of real spiking neurons and dynamic synapses for exploring the properties of computational neuroscience models and for building brain-inspired computing systems. The proposed architecture allows the on-chip configuration of a wide range of network connectivities, including recurrent and deep networks, with short-term and long-term plasticity. The device comprises 128 K analog synapse and 256 neuron circuits with biologically plausible dynamics and bi-stable spike-based plasticity mechanisms that endow it with on-line learning abilities. In addition to the analog circuits, the device comprises also asynchronous digital logic circuits for setting different synapse and neuron properties as well as different network configurations. This prototype device, fabricated using a 180 nm 1P6M CMOS process, occupies an area of 51.4 mm(2), and consumes approximately 4 mW for typical experiments, for example involving attractor networks. Here we describe the details of the overall architecture and of the individual circuits and present experimental results that showcase its potential. By supporting a wide range of cortical-like computational modules comprising plasticity mechanisms, this device will enable the realization of intelligent autonomous systems with on-line learning capabilities.

Deep Neural Network Emulation of a High-Order, WENO-Limited, Space-Time Reconstruction

NASA Astrophysics Data System (ADS)

Norman, M. R.; Hall, D. M.

2017-12-01

Deep Neural Networks (DNNs) have been used to emulate a number of processes in atmospheric models, including radiation and even so-called super-parameterization of moist convection. In each scenario, the DNN provides a good representation of the process even for inputs that have not been encountered before. More notably, they provide an emulation at a fraction of the cost of the original routine, giving speed-ups of 30× and even up to 200× compared to the runtime costs of the original routines. However, to our knowledge there has not been an investigation into using DNNs to emulate the dynamics. The most likely reason for this is that dynamics operators are typically both linear and low cost, meaning they cannot be sped up by a non-linear DNN emulation. However, there exist high-cost non-linear space-time dynamics operators that significantly reduce the number of parallel data transfers necessary to complete an atmospheric simulation. The WENO-limited Finite-Volume method with ADER-DT time integration is a prime example of this - needing only two parallel communications per large, fully limited time step. However, it comes at a high cost in terms of computation, which is why many would hesitate to use it. This talk investigates DNN emulation of the WENO-limited space-time finite-volume reconstruction procedure - the most expensive portion of this method, which densely clusters a large amount of non-linear computation. Different training techniques and network architectures are tested, and the accuracy and speed-up of each is given.

Reduced tobacco consumption, improved diet and life expectancy for 1988-1998: analysis of New Zealand and OECD data.

PubMed

Laugesen, Murray; Grace, Randolph C

2017-06-02

We compared changes in tobacco consumption and diet in relation to changes in life expectancy in 1988-1998 in 22 OECD (Organisation for Economic Cooperation and Development) countries. Between 1985 and 1995 using regression analysis we estimated differences in tobacco consumption per adult and the differences in the sum of atherogenic and thrombogenic indices against life expectancy. Each index was derived from the various fats per gram of food from standard texts, and from the annual measurements of fat in the food balance sheets of each country. In 1985-1995, New Zealand showed the largest decrease in tobacco consumption per adult (41%) and the greatest decrease (except for Switzerland) in the sum of atherogenic and thrombogenic indices (17%) as a measure of diet. New Zealand ranked first for life expectancy increases from 1988-1998 for men (3.2 years), women (2.8 years) and both sexes combined. Regression analyses revealed that increases in life expectancy across the OECD for males, but not females, were strongly associated with decreases in tobacco consumption, with a weaker effect of diet improvement. These results suggest that reduced tobacco consumption in 1985-1995 likely contributed to New Zealand's gains in life expectancy from 1988-1998.

Anti-thrombogenicity and permeability of polyethersulfone hollow fiber membrane with sulfonated alginate toward blood purification.

PubMed

Salimi, Esmaeil; Ghaee, Azadeh; Ismail, Ahmad Fauzi; Karimi, Majid

2018-04-30

The main aim of this study was to evaluate the suitability of sulfonated alginate as a modifying agent to enhance the hemocompatibility of self-fabricated polyethersulfone (PES) hollow fiber membrane for blood detoxification. Sodium alginate was sulfonated with a degree of 0.6 and immobilized on the membrane via surface amination and using glutaraldehyde as cross-linking agent. Coating layer not only improved the membrane surface hydrophilicity, but also induced -39.2 mV negative charges on the surface. Water permeability of the modified membrane was enhanced from 67 to 95 L/m 2 ·h·bar and flux recovery ratio increased more than 2-fold. Furthermore, the modified membrane presented higher platelet adhesion resistance (reduced by more than 90%) and prolonged coagulation time (35 s for APTT and 14 s for PT) in comparison with the pristine PES hollow fiber membrane, which verified the improved anti-thrombogenicity of the modified membrane. On the other hand, obtained membrane after 3 h coating could remove up-to 60% of the uremic toxins. According to the obtained data, sulfonated alginate can be a promising modifying agent for the future blood-contacting membrane and specially blood purification issues. Copyright © 2018 Elsevier B.V. All rights reserved.

Differences in coagulation among Asians and Caucasians and the implication for reconstructive microsurgery.

PubMed

Singhal, Dhruv; Smorodinsky, Emmanuil; Guo, Lifei

2011-01-01

Microvascular reconstructive surgery has seen a revival with the introduction of muscle-sparing perforator flaps. Recognition of potential ethnic differences in coagulation profiles would be important to a microvascular surgeon. Based on clinical observations, we hypothesize that Asian patients have a less thrombogenic coagulation profile than Caucasians. An extensive retrospective review was performed. The annual incidence of venous thromboembolism in the United States is generally accepted to range from 70 to 120 events per 100,000 people versus 16 to 17 events per 100,000 persons in Asia. Autopsy analysis of pulmonary embolism incidence was noted to be 15% in North Americans and less than 1% in Asian populations. Thromboelastography analysis of Asian and Caucasian patients undergoing cholecystectomy revealed different hemostatic mechanisms. Comparison of Asians and Caucasians undergoing the Fontan procedure revealed significantly lower postoperative factor levels in Asians than Caucasians. Baseline comparison of factor and serum levels revealed Asians with the least thrombogenic profiles compared with other ethnic groups. Asians and Caucasians demonstrate different baseline rates of deep vein thrombosis and pulmonary embolism, different hemostatic responses to surgery, and different baseline levels of clotting factors. Further study may lead to better pre-, intra-, and postoperative care of the free flap patient based on their ethnic coagulation profile. © Thieme Medical Publishers.

Emulating short-term synaptic dynamics with memristive devices

NASA Astrophysics Data System (ADS)

Berdan, Radu; Vasilaki, Eleni; Khiat, Ali; Indiveri, Giacomo; Serb, Alexandru; Prodromakis, Themistoklis

2016-01-01

Neuromorphic architectures offer great promise for achieving computation capacities beyond conventional Von Neumann machines. The essential elements for achieving this vision are highly scalable synaptic mimics that do not undermine biological fidelity. Here we demonstrate that single solid-state TiO2 memristors can exhibit non-associative plasticity phenomena observed in biological synapses, supported by their metastable memory state transition properties. We show that, contrary to conventional uses of solid-state memory, the existence of rate-limiting volatility is a key feature for capturing short-term synaptic dynamics. We also show how the temporal dynamics of our prototypes can be exploited to implement spatio-temporal computation, demonstrating the memristors full potential for building biophysically realistic neural processing systems.

Paired-pulse facilitation achieved in protonic/electronic hybrid indium gallium zinc oxide synaptic transistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Li Qiang, E-mail: guoliqiang@ujs.edu.cn; Ding, Jian Ning; Huang, Yu Kai

2015-08-15

Neuromorphic devices with paired pulse facilitation emulating that of biological synapses are the key to develop artificial neural networks. Here, phosphorus-doped nanogranular SiO{sub 2} electrolyte is used as gate dielectric for protonic/electronic hybrid indium gallium zinc oxide (IGZO) synaptic transistor. In such synaptic transistors, protons within the SiO{sub 2} electrolyte are deemed as neurotransmitters of biological synapses. Paired-pulse facilitation (PPF) behaviors for the analogous information were mimicked. The temperature dependent PPF behaviors were also investigated systematically. The results indicate that the protonic/electronic hybrid IGZO synaptic transistors would be promising candidates for inorganic synapses in artificial neural network applications.

Simple two-electrode biosignal amplifier.

PubMed

Dobrev, D; Neycheva, T; Mudrov, N

2005-11-01

A simple, cost effective circuit for a two-electrode non-differential biopotential amplifier is proposed. It uses a 'virtual ground' transimpedance amplifier and a parallel RC network for input common mode current equalisation, while the signal input impedance preserves its high value. With this innovative interface circuit, a simple non-inverting amplifier fully emulates high CMRR differential. The amplifier equivalent CMRR (typical range from 70-100 dB) is equal to the open loop gain of the operational amplifier used in the transimpedance interface stage. The circuit has very simple structure and utilises a small number of popular components. The amplifier is intended for use in various two-electrode applications, such as Holter-type monitors, defibrillators, ECG monitors, biotelemetry devices etc.

Assessment of penetrating thermal tissue damage/spread associated with PhotonBlade™, Valleylab™ Pencil, Valleylab™ EDGE™ Coated Pencil, PlasmaBlade® 3.0S and PlasmaBlade® 4.0 for intraoperative tissue dissection using the fresh extirpated porcine muscle model

NASA Astrophysics Data System (ADS)

Bennett, Haydon E.; Taylor, Scott D.; Fugett, James H.; Shrout, Joshua L.; Davison, Paul O.; Ryan, S. Eric; Coad, James E.

2017-02-01

Penetrating thermal tissue damage/spread is an important aspect of many electrosurgical devices and correlates with effective tissue cutting, hemostasis, preservation of adjacent critical structures and tissue healing. This study compared the thermal damage/spread associated with the PhotonBlade, Valleylab Pencil, Valleylab EDGE Coated Pencil, PlasmaBlade 3.0S and PlasmaBlade 4.0, when performing a single pass dynamic tissue cut in fresh extirpated porcine longissimus muscle. These devices were used in a fashion that emulated their use in the clinical setting. Each device's thermal damage/spread, at Minimum, Median and Maximum power input settings, was assessed with nitroblue tetrazolium viability staining in the WVU Pathology Laboratory for Translational Medicine. The thermal damage/spread associated with the PhotonBlade was compared with the other devices tested based on the individual treatment results (n=179 cuts combined). In summary, the PhotonBlade overall demonstrated the least penetrating thermal tissue damage/spread, followed by the PlasmaBlade 4.0, then Valleylab Pencil and PlasmaBlade 3.0S and then Valleylab EDGE Coated Pencil in order of increasing thermal damage/spread depths.

Synergistic Gating of Electro-Iono-Photoactive 2D Chalcogenide Neuristors: Coexistence of Hebbian and Homeostatic Synaptic Metaplasticity.

PubMed

John, Rohit Abraham; Liu, Fucai; Chien, Nguyen Anh; Kulkarni, Mohit R; Zhu, Chao; Fu, Qundong; Basu, Arindam; Liu, Zheng; Mathews, Nripan

2018-06-01

Emulation of brain-like signal processing with thin-film devices can lay the foundation for building artificially intelligent learning circuitry in future. Encompassing higher functionalities into single artificial neural elements will allow the development of robust neuromorphic circuitry emulating biological adaptation mechanisms with drastically lesser neural elements, mitigating strict process challenges and high circuit density requirements necessary to match the computational complexity of the human brain. Here, 2D transition metal di-chalcogenide (MoS 2 ) neuristors are designed to mimic intracellular ion endocytosis-exocytosis dynamics/neurotransmitter-release in chemical synapses using three approaches: (i) electronic-mode: a defect modulation approach where the traps at the semiconductor-dielectric interface are perturbed; (ii) ionotronic-mode: where electronic responses are modulated via ionic gating; and (iii) photoactive-mode: harnessing persistent photoconductivity or trap-assisted slow recombination mechanisms. Exploiting a novel multigated architecture incorporating electrical and optical biases, this incarnation not only addresses different charge-trapping probabilities to finely modulate the synaptic weights, but also amalgamates neuromodulation schemes to achieve "plasticity of plasticity-metaplasticity" via dynamic control of Hebbian spike-time dependent plasticity and homeostatic regulation. Coexistence of such multiple forms of synaptic plasticity increases the efficacy of memory storage and processing capacity of artificial neuristors, enabling design of highly efficient novel neural architectures. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantum simulation of a Fermi-Hubbard model using a semiconductor quantum dot array.

PubMed

Hensgens, T; Fujita, T; Janssen, L; Li, Xiao; Van Diepen, C J; Reichl, C; Wegscheider, W; Das Sarma, S; Vandersypen, L M K

2017-08-02

Interacting fermions on a lattice can develop strong quantum correlations, which are the cause of the classical intractability of many exotic phases of matter. Current efforts are directed towards the control of artificial quantum systems that can be made to emulate the underlying Fermi-Hubbard models. Electrostatically confined conduction-band electrons define interacting quantum coherent spin and charge degrees of freedom that allow all-electrical initialization of low-entropy states and readily adhere to the Fermi-Hubbard Hamiltonian. Until now, however, the substantial electrostatic disorder of the solid state has meant that only a few attempts at emulating Fermi-Hubbard physics on solid-state platforms have been made. Here we show that for gate-defined quantum dots this disorder can be suppressed in a controlled manner. Using a semi-automated and scalable set of experimental tools, we homogeneously and independently set up the electron filling and nearest-neighbour tunnel coupling in a semiconductor quantum dot array so as to simulate a Fermi-Hubbard system. With this set-up, we realize a detailed characterization of the collective Coulomb blockade transition, which is the finite-size analogue of the interaction-driven Mott metal-to-insulator transition. As automation and device fabrication of semiconductor quantum dots continue to improve, the ideas presented here will enable the investigation of the physics of ever more complex many-body states using quantum dots.

ATM LAN Emulation: Getting from Here to There.

ERIC Educational Resources Information Center

Learn, Larry L., Ed.

1995-01-01

Discusses current LAN (local area network) configuration and explains ATM (asynchronous transfer mode) as the future telecommunications transport. Highlights include LAN emulation, which enables the interconnection of legacy LANs and the new ATM environment; virtual LANs; broadcast servers; and standards. (LRW)

Statistical emulators of maize, rice, soybean and wheat yields from global gridded crop models

DOE PAGES

Blanc, Élodie

2017-01-26

This study provides statistical emulators of crop yields based on global gridded crop model simulations from the Inter-Sectoral Impact Model Intercomparison Project Fast Track project. The ensemble of simulations is used to build a panel of annual crop yields from five crop models and corresponding monthly summer weather variables for over a century at the grid cell level globally. This dataset is then used to estimate, for each crop and gridded crop model, the statistical relationship between yields, temperature, precipitation and carbon dioxide. This study considers a new functional form to better capture the non-linear response of yields to weather,more » especially for extreme temperature and precipitation events, and now accounts for the effect of soil type. In- and out-of-sample validations show that the statistical emulators are able to replicate spatial patterns of yields crop levels and changes overtime projected by crop models reasonably well, although the accuracy of the emulators varies by model and by region. This study therefore provides a reliable and accessible alternative to global gridded crop yield models. By emulating crop yields for several models using parsimonious equations, the tools provide a computationally efficient method to account for uncertainty in climate change impact assessments.« less

Emulation, imitation, over-imitation and the scope of culture for child and chimpanzee

PubMed Central

Whiten, Andrew; McGuigan, Nicola; Marshall-Pescini, Sarah; Hopper, Lydia M.

2009-01-01

We describe our recent studies of imitation and cultural transmission in chimpanzees and children, which question late twentieth-century characterizations of children as imitators, but chimpanzees as emulators. As emulation entails learning only about the results of others' actions, it has been thought to curtail any capacity to sustain cultures. Recent chimpanzee diffusion experiments have by contrast documented a significant capacity for copying local behavioural traditions. Additionally, in recent ‘ghost’ experiments with no model visible, chimpanzees failed to replicate the object movements on which emulation is supposed to focus. We conclude that chimpanzees rely more on imitation and have greater cultural capacities than previously acknowledged. However, we also find that they selectively apply a range of social learning processes that include emulation. Recent studies demonstrating surprisingly unselective ‘over-imitation’ in children suggest that children's propensity to imitate has been underestimated too. We discuss the implications of these developments for the nature of social learning and culture in the two species. Finally, our new experiments directly address cumulative cultural learning. Initial results demonstrate a relative conservatism and conformity in chimpanzees' learning, contrasting with cumulative cultural learning in young children. This difference may contribute much to the contrast in these species' capacities for cultural evolution. PMID:19620112

Internal monitoring of GBTx emulator using IPbus for CBM experiment

NASA Astrophysics Data System (ADS)

Mandal, Swagata; Zabolotny, Wojciech; Sau, Suman; Chkrabarti, Amlan; Saini, Jogender; Chattopadhyay, Subhasis; Pal, Sushanta Kumar

2015-09-01

The Compressed Baryonic Matter (CBM) experiment is a part of the Facility for Antiproton and Ion Research (FAIR) in Darmstadt at GSI. In CBM experiment a precisely time synchronized fault tolerant self-triggered electronics is required for Data Acquisition (DAQ) system in CBM experiments which can support high data rate (up to several TB/s). As a part of the implementation of the DAQ system of Muon Chamber (MUCH) which is one of the important detectors in CBM experiment, a FPGA based Gigabit Transceiver (GBTx) emulator is implemented. Readout chain for MUCH consists of XYTER chips (Front end electronics) which will be directly connected to detector, GBTx emulator, Data Processing Board (DPB) and First level event selector board (FLIB) with backend software interface. GBTx emulator will be connected with the XYTER emulator through LVDS (Low Voltage Differential Signalling) line in the front end and in the back end it is connected with DPB through 4.8 Gbps optical link. IPBus over Ethernet is used for internal monitoring of the registers within the GBTx. In IPbus implementation User Datagram Protocol (UDP) stack is used in transport layer of OSI model so that GBTx can be controlled remotely. A Python script is used at computer side to drive IPbus controller.

Statistical emulators of maize, rice, soybean and wheat yields from global gridded crop models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blanc, Élodie

This study provides statistical emulators of crop yields based on global gridded crop model simulations from the Inter-Sectoral Impact Model Intercomparison Project Fast Track project. The ensemble of simulations is used to build a panel of annual crop yields from five crop models and corresponding monthly summer weather variables for over a century at the grid cell level globally. This dataset is then used to estimate, for each crop and gridded crop model, the statistical relationship between yields, temperature, precipitation and carbon dioxide. This study considers a new functional form to better capture the non-linear response of yields to weather,more » especially for extreme temperature and precipitation events, and now accounts for the effect of soil type. In- and out-of-sample validations show that the statistical emulators are able to replicate spatial patterns of yields crop levels and changes overtime projected by crop models reasonably well, although the accuracy of the emulators varies by model and by region. This study therefore provides a reliable and accessible alternative to global gridded crop yield models. By emulating crop yields for several models using parsimonious equations, the tools provide a computationally efficient method to account for uncertainty in climate change impact assessments.« less

Accelerated healing of cardiovascular textiles promoted by an RGD peptide.

PubMed

Tweden, K S; Harasaki, H; Jones, M; Blevitt, J M; Craig, W S; Pierschbacher, M; Helmus, M N

1995-07-01

Polytetrafluoroethylene (PTFE) and polyethylene terephthalate (Dacron polyester) fabrics are used extensively in cardiovascular devices, e.g. heart valve sewing cuffs and vascular prostheses. While devices containing these fabrics are generally successful, it is recognized that fabrics cause complications prior to tissue ingrowth due to their thrombogenic nature. A surface active synthetic peptide, called PepTite Coating (PepTite), which was modeled after the cell attachment domain of human fibronectin has been marketed as a biocompatible coating. This peptide stimulates cell attachment through the arginine-glycine-aspartic acid (RGD) sequence. Modification of medical implants with PepTite has been shown to promote ingrowth of surrounding cells into the material leading to better tissue integration, reduced inflammation and reduced fibrotic encapsulation. In this study, polyester and PTFE textiles were modified with PepTite. The effectiveness of this coating in enhancing wound healing was investigated in a simple vascular and cardiac valve model. Our results indicate that the RGD-containing peptide, PepTite, promoted the formation of an endothelial-like cell layer on both polyester and PTFE vascular patches in the dog model. PepTite was also found to promote the formation of a significantly thinner neointima (pannus) on polyester as compared to that on its uncoated control. These results were corroborated in the cardiac valve model in which a greater amount of thin pannus and less thrombus were seen on coated polyester sewing cuffs than on control uncoated cuffs. This research shows the promising tissue response to RGD coated textiles and the potential role of this peptide in material passivation via accelerated healing.

Functional electronic inversion layers at ferroelectric domain walls

NASA Astrophysics Data System (ADS)

Mundy, J. A.; Schaab, J.; Kumagai, Y.; Cano, A.; Stengel, M.; Krug, I. P.; Gottlob, D. M.; Doğanay, H.; Holtz, M. E.; Held, R.; Yan, Z.; Bourret, E.; Schneider, C. M.; Schlom, D. G.; Muller, D. A.; Ramesh, R.; Spaldin, N. A.; Meier, D.

2017-06-01

Ferroelectric domain walls hold great promise as functional two-dimensional materials because of their unusual electronic properties. Particularly intriguing are the so-called charged walls where a polarity mismatch causes local, diverging electrostatic potentials requiring charge compensation and hence a change in the electronic structure. These walls can exhibit significantly enhanced conductivity and serve as a circuit path. The development of all-domain-wall devices, however, also requires walls with controllable output to emulate electronic nano-components such as diodes and transistors. Here we demonstrate electric-field control of the electronic transport at ferroelectric domain walls. We reversibly switch from resistive to conductive behaviour at charged walls in semiconducting ErMnO3. We relate the transition to the formation--and eventual activation--of an inversion layer that acts as the channel for the charge transport. The findings provide new insight into the domain-wall physics in ferroelectrics and foreshadow the possibility to design elementary digital devices for all-domain-wall circuitry.

Robust self-cleaning and micromanipulation capabilities of gecko spatulae and their bio-mimics

NASA Astrophysics Data System (ADS)

Xu, Quan; Wan, Yiyang; Hu, Travis Shihao; Liu, Tony X.; Tao, Dashuai; Niewiarowski, Peter H.; Tian, Yu; Liu, Yue; Dai, Liming; Yang, Yanqing; Xia, Zhenhai

2015-11-01

Geckos have the extraordinary ability to prevent their sticky feet from fouling while running on dusty walls and ceilings. Understanding gecko adhesion and self-cleaning mechanisms is essential for elucidating animal behaviours and rationally designing gecko-inspired devices. Here we report a unique self-cleaning mechanism possessed by the nano-pads of gecko spatulae. The difference between the velocity-dependent particle-wall adhesion and the velocity-independent spatula-particle dynamic response leads to a robust self-cleaning capability, allowing geckos to efficiently dislodge dirt during their locomotion. Emulating this natural design, we fabricate artificial spatulae and micromanipulators that show similar effects, and that provide a new way to manipulate micro-objects. By simply tuning the pull-off velocity, our gecko-inspired micromanipulators, made of synthetic microfibers with graphene-decorated micro-pads, can easily pick up, transport, and drop-off microparticles for precise assembling. This work should open the door to the development of novel self-cleaning adhesives, smart surfaces, microelectromechanical systems, biomedical devices, and more.

Channel add-drop filter based on dual photonic crystal cavities in push-pull mode.

PubMed

Poulton, Christopher V; Zeng, Xiaoge; Wade, Mark T; Popović, Miloš A

2015-09-15

We demonstrate an add-drop filter based on a dual photonic crystal nanobeam cavity system that emulates the operation of a traveling wave resonator, and, thus, provides separation of the through and drop port transmission from the input port. The device is on a 3×3  mm chip fabricated in an advanced microelectronics silicon-on-insulator complementary metal-oxide semiconductor (SOI CMOS) process (IBM 45 nm SOI) without any foundry process modifications. The filter shows 1 dB of insertion loss in the drop port with a 3 dB bandwidth of 64 GHz, and 16 dB extinction in the through port. To the best of our knowledge, this is the first implementation of a port-separating, add-drop filter based on standing wave cavities coupled to conventional waveguides, and demonstrates a performance that suggests potential for photonic crystal devices within optical immersion lithography-based advanced CMOS electronics-photonics integration.

Towards image-guided atrial septal defect repair: an ex vivo analysis

NASA Astrophysics Data System (ADS)

Kwartowitz, David M.; Mefleh, Fuad N.; Baker, George H.

2012-02-01

The use of medical images in the operating room for navigation and planning is well established in many clinical disciplines. In cardiology, the use of fluoroscopy for the placement of catheters within the heart has become the standard of care. While fluoroscopy provides a live video sequence with the current location, it poses risks the patient and clinician through exposure to radiation. Radiation dose is cumulative and thus children are at even greater risk from exposure. To reduce the use of radiation, and improve surgical technique we have begun development of an image-guided navigation system, which can deliver therapeutic devices via catheter. In this work we have demonstrated the intrinsic properties of our imaging system, which have led to the development of a phantom emulating a childs heart with an ASD. Further investigation into the use of this information, in a series of mock clinical experiments, will be performed to design procedures for inserting devices into the heart while minimizing fluoroscopy use.

Quantum optical emulation of molecular vibronic spectroscopy using a trapped-ion device.

PubMed

Shen, Yangchao; Lu, Yao; Zhang, Kuan; Zhang, Junhua; Zhang, Shuaining; Huh, Joonsuk; Kim, Kihwan

2018-01-28

Molecules are one of the most demanding quantum systems to be simulated by quantum computers due to their complexity and the emergent role of quantum nature. The recent theoretical proposal of Huh et al. (Nature Photon., 9, 615 (2015)) showed that a multi-photon network with a Gaussian input state can simulate a molecular spectroscopic process. Here, we present the first quantum device that generates a molecular spectroscopic signal with the phonons in a trapped ion system, using SO 2 as an example. In order to perform reliable Gaussian sampling, we develop the essential experimental technology with phonons, which includes the phase-coherent manipulation of displacement, squeezing, and rotation operations with multiple modes in a single realization. The required quantum optical operations are implemented through Raman laser beams. The molecular spectroscopic signal is reconstructed from the collective projection measurements for the two-phonon-mode. Our experimental demonstration will pave the way to large-scale molecular quantum simulations, which are classically intractable, but would be easily verifiable by real molecular spectroscopy.

A geological history of reflecting optics

PubMed Central

Parker, Andrew Richard

2005-01-01

Optical reflectors in animals are diverse and ancient. The first image-forming eye appeared around 543 million years ago. This introduced vision as a selection pressure in the evolution of animals, and consequently the evolution of adapted optical devices. The earliest known optical reflectors—diffraction gratings—are 515 Myr old. The subsequent fossil record preserves multilayer reflectors, including liquid crystals and mirrors, ‘white’ and ‘blue’ scattering structures, antireflective surfaces and the very latest addition to optical physics—photonic crystals. The aim of this article is to reveal the diversity of reflecting optics in nature, introducing the first appearance of some reflector types as they appear in the fossil record as it stands (which includes many new records) and backdating others in geological time through evolutionary analyses. This article also reveals the commercial potential for these optical devices, in terms of lessons from their nano-level designs and the possible emulation of their engineering processes—molecular self-assembly. PMID:16849159

Memristive Ion Channel-Doped Biomembranes as Synaptic Mimics.

PubMed

Najem, Joseph S; Taylor, Graham J; Weiss, Ryan J; Hasan, Md Sakib; Rose, Garrett; Schuman, Catherine D; Belianinov, Alex; Collier, C Patrick; Sarles, Stephen A

2018-05-22

Solid-state neuromorphic systems based on transistors or memristors have yet to achieve the interconnectivity, performance, and energy efficiency of the brain due to excessive noise, undesirable material properties, and nonbiological switching mechanisms. Here we demonstrate that an alamethicin-doped, synthetic biomembrane exhibits memristive behavior, emulates key synaptic functions including paired-pulse facilitation and depression, and enables learning and computing. Unlike state-of-the-art devices, our two-terminal, biomolecular memristor features similar structure (biomembrane), switching mechanism (ion channels), and ionic transport modality as biological synapses while operating at considerably lower power. The reversible and volatile voltage-driven insertion of alamethicin peptides into an insulating lipid bilayer creates conductive pathways that exhibit pinched current-voltage hysteresis at potentials above their insertion threshold. Moreover, the synapse-like dynamic properties of the biomolecular memristor allow for simplified learning circuit implementations. Low-power memristive devices based on stimuli-responsive biomolecules represent a major advance toward implementation of full synaptic functionality in neuromorphic hardware.

A Pervasive Social Networking Application: I-NFC enabled Florist Smart Advisor

NASA Astrophysics Data System (ADS)

Swee Wen, Khoo; Mahinderjit Singh, Manmeet

2016-11-01

Location based service is an information and entertainment service, accessible with mobile devices through the mobile network and utilizing the ability to make use of the geographical position of the mobile device. NFC location based service is using one of the modes of NFC such as peer-to-peer, reader/writer, and card emulation to obtain the information of the object and then get the location of the object. In this paper, the proposed solution is I- NFC-enabled Pervasive Social Networking apps for florists. It combines the NFC location based service with Online Social Network (OSN). In addition, a smart advisor in the system to provide output in making their own decision while purchasing products.The development of the system demonstrates that a designed commerce site is provided which enable a communication between NFC-enabled smartphone, NFC-enabled application and OSN. GPS functionalities also implemented to provide map and location of business services. Smart advisor also designed to provide information for users who do not have ideas what to purchase.

In situ patterned micro 3D liver constructs for parallel toxicology testing in a fluidic device

PubMed Central

Skardal, Aleksander; Devarasetty, Mahesh; Soker, Shay; Hall, Adam R

2017-01-01

3D tissue models are increasingly being implemented for drug and toxicology testing. However, the creation of tissue-engineered constructs for this purpose often relies on complex biofabrication techniques that are time consuming, expensive, and difficult to scale up. Here, we describe a strategy for realizing multiple tissue constructs in a parallel microfluidic platform using an approach that is simple and can be easily scaled for high-throughput formats. Liver cells mixed with a UV-crosslinkable hydrogel solution are introduced into parallel channels of a sealed microfluidic device and photopatterned to produce stable tissue constructs in situ. The remaining uncrosslinked material is washed away, leaving the structures in place. By using a hydrogel that specifically mimics the properties of the natural extracellular matrix, we closely emulate native tissue, resulting in constructs that remain stable and functional in the device during a 7-day culture time course under recirculating media flow. As proof of principle for toxicology analysis, we expose the constructs to ethyl alcohol (0–500 mM) and show that the cell viability and the secretion of urea and albumin decrease with increasing alcohol exposure, while markers for cell damage increase. PMID:26355538

In situ patterned micro 3D liver constructs for parallel toxicology testing in a fluidic device.

PubMed

Skardal, Aleksander; Devarasetty, Mahesh; Soker, Shay; Hall, Adam R

2015-09-10

3D tissue models are increasingly being implemented for drug and toxicology testing. However, the creation of tissue-engineered constructs for this purpose often relies on complex biofabrication techniques that are time consuming, expensive, and difficult to scale up. Here, we describe a strategy for realizing multiple tissue constructs in a parallel microfluidic platform using an approach that is simple and can be easily scaled for high-throughput formats. Liver cells mixed with a UV-crosslinkable hydrogel solution are introduced into parallel channels of a sealed microfluidic device and photopatterned to produce stable tissue constructs in situ. The remaining uncrosslinked material is washed away, leaving the structures in place. By using a hydrogel that specifically mimics the properties of the natural extracellular matrix, we closely emulate native tissue, resulting in constructs that remain stable and functional in the device during a 7-day culture time course under recirculating media flow. As proof of principle for toxicology analysis, we expose the constructs to ethyl alcohol (0-500 mM) and show that the cell viability and the secretion of urea and albumin decrease with increasing alcohol exposure, while markers for cell damage increase.

Perception-based synthetic cueing for night vision device rotorcraft hover operations

NASA Astrophysics Data System (ADS)

Bachelder, Edward N.; McRuer, Duane

2002-08-01

Helicopter flight using night-vision devices (NVDs) is difficult to perform, as evidenced by the high accident rate associated with NVD flight compared to day operation. The approach proposed in this paper is to augment the NVD image with synthetic cueing, whereby the cues would emulate position and motion and appear to be actually occurring in physical space on which they are overlaid. Synthetic cues allow for selective enhancement of perceptual state gains to match the task requirements. A hover cue set was developed based on an analogue of a physical target used in a flight handling qualities tracking task, a perceptual task analysis for hover, and fundamentals of human spatial perception. The display was implemented on a simulation environment, constructed using a virtual reality device, an ultrasound head-tracker, and a fixed-base helicopter simulator. Seven highly trained helicopter pilots were used as experimental subjects and tasked to maintain hover in the presence of aircraft positional disturbances while viewing a synthesized NVD environment and the experimental hover cues. Significant performance improvements were observed when using synthetic cue augmentation. This paper demonstrates that artificial magnification of perceptual states through synthetic cueing can be an effective method of improving night-vision helicopter hover operations.

Quantification of uncertainties in the tsunami hazard for Cascadia using statistical emulation

NASA Astrophysics Data System (ADS)

Guillas, S.; Day, S. J.; Joakim, B.

2016-12-01

We present new high resolution tsunami wave propagation and coastal inundation for the Cascadia region in the Pacific Northwest. The coseismic representation in this analysis is novel, and more realistic than in previous studies, as we jointly parametrize multiple aspects of the seabed deformation. Due to the large computational cost of such simulators, statistical emulation is required in order to carry out uncertainty quantification tasks, as emulators efficiently approximate simulators. The emulator replaces the tsunami model VOLNA by a fast surrogate, so we are able to efficiently propagate uncertainties from the source characteristics to wave heights, in order to probabilistically assess tsunami hazard for Cascadia. We employ a new method for the design of the computer experiments in order to reduce the number of runs while maintaining good approximations properties of the emulator. Out of the initial nine parameters, mostly describing the geometry and time variation of the seabed deformation, we drop two parameters since these turn out to not have an influence on the resulting tsunami waves at the coast. We model the impact of another parameter linearly as its influence on the wave heights is identified as linear. We combine this screening approach with the sequential design algorithm MICE (Mutual Information for Computer Experiments), that adaptively selects the input values at which to run the computer simulator, in order to maximize the expected information gain (mutual information) over the input space. As a result, the emulation is made possible and accurate. Starting from distributions of the source parameters that encapsulate geophysical knowledge of the possible source characteristics, we derive distributions of the tsunami wave heights along the coastline.

Feasibility of neuro-morphic computing to emulate error-conflict based decision making.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Branch, Darren W.

2009-09-01

A key aspect of decision making is determining when errors or conflicts exist in information and knowing whether to continue or terminate an action. Understanding the error-conflict processing is crucial in order to emulate higher brain functions in hardware and software systems. Specific brain regions, most notably the anterior cingulate cortex (ACC) are known to respond to the presence of conflicts in information by assigning a value to an action. Essentially, this conflict signal triggers strategic adjustments in cognitive control, which serve to prevent further conflict. The most probable mechanism is the ACC reports and discriminates different types of feedback,more » both positive and negative, that relate to different adaptations. Unique cells called spindle neurons that are primarily found in the ACC (layer Vb) are known to be responsible for cognitive dissonance (disambiguation between alternatives). Thus, the ACC through a specific set of cells likely plays a central role in the ability of humans to make difficult decisions and solve challenging problems in the midst of conflicting information. In addition to dealing with cognitive dissonance, decision making in high consequence scenarios also relies on the integration of multiple sets of information (sensory, reward, emotion, etc.). Thus, a second area of interest for this proposal lies in the corticostriatal networks that serve as an integration region for multiple cognitive inputs. In order to engineer neurological decision making processes in silicon devices, we will determine the key cells, inputs, and outputs of conflict/error detection in the ACC region. The second goal is understand in vitro models of corticostriatal networks and the impact of physical deficits on decision making, specifically in stressful scenarios with conflicting streams of data from multiple inputs. We will elucidate the mechanisms of cognitive data integration in order to implement a future corticostriatal-like network in silicon devices for improved decision processing.« less

Emulation of Condensed Fuel Flames Using a Burning Rate Emulator (BRE) in Microgravity

NASA Technical Reports Server (NTRS)

Markan, A.; Quintiere, J. G.; Sunderland, P. B.; De Ris, J. L.; Stocker, D. P.

2017-01-01

The Burning Rate Emulator (BRE) is a gaseous fuel burner developed to emulate the burning of condensed phase fuels. The current study details several tests at the NASA Glenn 5-s drop facility to test the BRE technique in microgravity conditions. The tests are conducted for two burner diameters, 25 mm and 50 mm respectively, with methane and ethylene as the fuels. The ambient pressure, oxygen content and fuel flow rate are additional parameters. The microgravity results exhibit a nominally hemispherical flame with decelerating growth and quasi-steady heat flux after about 5 seconds. The BRE burner was evaluated with a transient analysis to assess the extent of steady-state achieved. The burning rate and flame height recorded at the end of the drop are correlated using two steady-state purely diffusive models. A higher burning rate for the bigger burner as compared to theory indicates the significance of gas radiation. The effect of the ambient pressure and oxygen concentration on the heat of gasification are also examined.

Design of testbed and emulation tools

NASA Technical Reports Server (NTRS)

Lundstrom, S. F.; Flynn, M. J.

1986-01-01

The research summarized was concerned with the design of testbed and emulation tools suitable to assist in projecting, with reasonable accuracy, the expected performance of highly concurrent computing systems on large, complete applications. Such testbed and emulation tools are intended for the eventual use of those exploring new concurrent system architectures and organizations, either as users or as designers of such systems. While a range of alternatives was considered, a software based set of hierarchical tools was chosen to provide maximum flexibility, to ease in moving to new computers as technology improves and to take advantage of the inherent reliability and availability of commercially available computing systems.

On stethoscope design: a challenge for biomedical circuit designers.

PubMed

Hahn, A W

2001-01-01

Most clinicians learned the art and science of auscultation using an acoustic stethoscope. While many models of electronic stethoscopes have been marketed over the years, none of them seem to do a very good job of emulating the most common forms of acoustic stethoscopes available. This paper is an appeal to biomedical circuit designers to learn more about the acoustics of commonly used stethoscopes and to develop an appropriate group of circuits which would emulate them much like music synthesizers can emulate almost any musical instrument. The implications are for creative designers to move toward a rational and acceptable design for both personal physician use and for telemedicine.

The Outline of Personhood Law Regarding Artificial Intelligences and Emulated Human Entities

NASA Astrophysics Data System (ADS)

Muzyka, Kamil

2013-12-01

On the verge of technological breakthroughs, which define and revolutionize our understanding of intelligence, cognition, and personhood, especially when speaking of artificial intelligences and mind uploads, one must consider the legal implications of granting personhood rights to artificial intelligences or emulated human entities

Emulation of the MBM-MEDUSA model: exploring the sea level and the basin-to-shelf transfer influence on the system dynamics

NASA Astrophysics Data System (ADS)

Ermakov, Ilya; Crucifix, Michel; Munhoven, Guy

2013-04-01

Complex climate models require high computational burden. However, computational limitations may be avoided by using emulators. In this work we present several approaches for dynamical emulation (also called metamodelling) of the Multi-Box Model (MBM) coupled to the Model of Early Diagenesis in the Upper Sediment A (MEDUSA) that simulates the carbon cycle of the ocean and atmosphere [1]. We consider two experiments performed on the MBM-MEDUSA that explore the Basin-to-Shelf Transfer (BST) dynamics. In both experiments the sea level is varied according to a paleo sea level reconstruction. Such experiments are interesting because the BST is an important cause of the CO2 variation and the dynamics is potentially nonlinear. The output that we are interested in is the variation of the carbon dioxide partial pressure in the atmosphere over the Pleistocene. The first experiment considers that the BST is fixed constant during the simulation. In the second experiment the BST is interactively adjusted according to the sea level, since the sea level is the primary control of the growth and decay of coral reefs and other shelf carbon reservoirs. The main aim of the present contribution is to create a metamodel of the MBM-MEDUSA using the Dynamic Emulation Modelling methodology [2] and compare the results obtained using linear and non-linear methods. The first step in the emulation methodology used in this work is to identify the structure of the metamodel. In order to select an optimal approach for emulation we compare the results of identification obtained by the simple linear and more complex nonlinear models. In order to identify the metamodel in the first experiment the simple linear regression and the least-squares method is sufficient to obtain a 99,9% fit between the temporal outputs of the model and the metamodel. For the second experiment the MBM's output is highly nonlinear. In this case we apply nonlinear models, such as, NARX, Hammerstein model, and an 'ad-hoc' switching model. After the identification we perform the parameter mapping using spline interpolation and validate the emulator on a new set of parameters. References: [1] G. Munhoven, "Glacial-interglacial rain ratio changes: Implications for atmospheric CO2 and ocean-sediment interaction," Deep-Sea Res Pt II, vol. 54, pp. 722-746, 2007. [2] A. Castelletti et al., "A general framework for Dynamic Emulation Modelling in environmental problems," Environ Modell Softw, vol. 34, pp. 5-18, 2012.

Multi-level emulation of complex climate model responses to boundary forcing data

NASA Astrophysics Data System (ADS)

Tran, Giang T.; Oliver, Kevin I. C.; Holden, Philip B.; Edwards, Neil R.; Sóbester, András; Challenor, Peter

2018-04-01

Climate model components involve both high-dimensional input and output fields. It is desirable to efficiently generate spatio-temporal outputs of these models for applications in integrated assessment modelling or to assess the statistical relationship between such sets of inputs and outputs, for example, uncertainty analysis. However, the need for efficiency often compromises the fidelity of output through the use of low complexity models. Here, we develop a technique which combines statistical emulation with a dimensionality reduction technique to emulate a wide range of outputs from an atmospheric general circulation model, PLASIM, as functions of the boundary forcing prescribed by the ocean component of a lower complexity climate model, GENIE-1. Although accurate and detailed spatial information on atmospheric variables such as precipitation and wind speed is well beyond the capability of GENIE-1's energy-moisture balance model of the atmosphere, this study demonstrates that the output of this model is useful in predicting PLASIM's spatio-temporal fields through multi-level emulation. Meaningful information from the fast model, GENIE-1 was extracted by utilising the correlation between variables of the same type in the two models and between variables of different types in PLASIM. We present here the construction and validation of several PLASIM variable emulators and discuss their potential use in developing a hybrid model with statistical components.

Emulating Simulations of Cosmic Dawn for 21 cm Power Spectrum Constraints on Cosmology, Reionization, and X-Ray Heating

NASA Astrophysics Data System (ADS)

Kern, Nicholas S.; Liu, Adrian; Parsons, Aaron R.; Mesinger, Andrei; Greig, Bradley

2017-10-01

Current and upcoming radio interferometric experiments are aiming to make a statistical characterization of the high-redshift 21 cm fluctuation signal spanning the hydrogen reionization and X-ray heating epochs of the universe. However, connecting 21 cm statistics to the underlying physical parameters is complicated by the theoretical challenge of modeling the relevant physics at computational speeds quick enough to enable exploration of the high-dimensional and weakly constrained parameter space. In this work, we use machine learning algorithms to build a fast emulator that can accurately mimic an expensive simulation of the 21 cm signal across a wide parameter space. We embed our emulator within a Markov Chain Monte Carlo framework in order to perform Bayesian parameter constraints over a large number of model parameters, including those that govern the Epoch of Reionization, the Epoch of X-ray Heating, and cosmology. As a worked example, we use our emulator to present an updated parameter constraint forecast for the Hydrogen Epoch of Reionization Array experiment, showing that its characterization of a fiducial 21 cm power spectrum will considerably narrow the allowed parameter space of reionization and heating parameters, and could help strengthen Planck's constraints on {σ }8. We provide both our generalized emulator code and its implementation specifically for 21 cm parameter constraints as publicly available software.

Platelet aggregation, eicosanoid production and thrombogenic ratio in individuals at high cardiovascular risk consuming meat enriched in walnut paste. A crossover, placebo-controlled study.

PubMed

Canales, Amaia; Bastida, Sara; Librelottto, Josana; Nus, Meritxell; Sánchez-Muniz, Francisco J; Benedi, Juana

2009-07-01

Walnut consumption produces beneficial cardiovascular effects. The aim of the present study is to compare the effects of meat enriched in walnut paste (WM) and low-fat meat (LM) consumptions on platelet aggregation, plasma thromboxane A2 (TXA2, measured as TXB2), prostacyclin I2 (PGI2, as 6-keto-PGF1alpha) and the thrombogenic ratio (TXB2/6-keto-PGF1alpha) in volunteers at high CVD risk. Twenty-two adults were placed on a random, non-blinded crossover study involving two test periods (five portions WM/week for 5 week; five portions LM/week for 5 week) separated by a 4- to 6-week washout period. The participants were asked to complete a diet record throughout the study. Platelet aggregation, plasma TXB2, 6-keto-PGF1alpha production and the TXB2/6-keto-PGF1alpha ratio were determined at baseline and at weeks 3 and 5 for the two dietary periods. The WM diet contains a lower SFA content, a higher concentration of PUFA and a more favourable n-6/n-3 ratio than the LM diet. Significant time x treatment interactions were observed for TXB2 (P = 0.048) and the TXB2/6-keto-PGF1alpha ratio (P = 0.028). The WM diet significantly increased the level of 6-keto-PGF1alpha (P = 0.037) and decreased the TXB2/6-keto-PGF1alpha ratio (P = 0.048). At week 5, significant differences (P < 0.05) between treatments were found for maximum aggregation rate, TXB2 values and the TXB2/6-keto-PGF1alpha ratio. The effects on TXB2 and the TXB2/6-keto-PGF1alpha ratio were time-course dependent (P = 0.019 and 0.011, respectively). The WM and LM diets reduced TXB2 levels most (P = 0.050) in obese individuals, while the TXB2/6-keto-PGF1alpha ratio decreased most (P = 0.066) in volunteers whose serum cholesterol levels were > or = 2200 mg/l. The WM diet should be considered a functional meat because it improves the thrombogenic status mainly in individuals with high-cholesterol levels or high BMI.

BSM (+BMM) Data Emulator Dynamic Interrogative Data Capture (DIDC) Assessment Report: Proof of Concept

DOT National Transportation Integrated Search

2016-04-01

The report documents the study conducted as part of the BSM+BMM Data Emulator project, to examine the DIDC concept and determine the best set of DIDC parameters that provide the most support to the performance measure estimation process with the leas...

Loop Group Parakeet Virtual Cable Concept Demonstrator

NASA Astrophysics Data System (ADS)

Dowsett, T.; McNeill, T. C.; Reynolds, A. B.; Blair, W. D.

2002-07-01

The Parakeet Virtual Cable (PVC) concept demonstrator uses the Ethernet Local Area Network (LAN) laid for the Battle Command Support System (BCSS) to connect the Parakeet DVT(DA) (voice terminal) to the Parakeet multiplexer. This currently requires pairs of PVC interface units to be installed for each DVT(DA) . To reduce the cost of a PVC installation, the concept of a Loop Group Parakeet Virtual Cable (LGPVC) was proposed. This device was designed to replace the up to 30 PVC boxes and the multiplexer at the multiplexer side of a PVC installation. While the demonstrator is largely complete, testing has revealed an incomplete understanding of how to emulate the proprietary handshaking occurring between the circuit switch and the multiplexer. The LGPVC concept cannot yet be demonstrated.

Force Feedback Joystick

NASA Technical Reports Server (NTRS)

1997-01-01

I-FORCE, a computer peripheral from Immersion Corporation, was derived from virtual environment and human factors research at the Advanced Displays and Spatial Perception Laboratory at Ames Research Center in collaboration with Stanford University Center for Design Research. Entrepreneur Louis Rosenberg, a former Stanford researcher, now president of Immersion, collaborated with Dr. Bernard Adelstein at Ames on studies of perception in virtual reality. The result was an inexpensive way to incorporate motors and a sophisticated microprocessor into joysticks and other game controllers. These devices can emulate the feel of a car on the skid, a crashing plane, the bounce of a ball, compressed springs, or other physical phenomenon. The first products incorporating I-FORCE technology include CH- Products' line of FlightStick and CombatStick controllers.

A reconfigurable on-line learning spiking neuromorphic processor comprising 256 neurons and 128K synapses

PubMed Central

Qiao, Ning; Mostafa, Hesham; Corradi, Federico; Osswald, Marc; Stefanini, Fabio; Sumislawska, Dora; Indiveri, Giacomo

2015-01-01

Implementing compact, low-power artificial neural processing systems with real-time on-line learning abilities is still an open challenge. In this paper we present a full-custom mixed-signal VLSI device with neuromorphic learning circuits that emulate the biophysics of real spiking neurons and dynamic synapses for exploring the properties of computational neuroscience models and for building brain-inspired computing systems. The proposed architecture allows the on-chip configuration of a wide range of network connectivities, including recurrent and deep networks, with short-term and long-term plasticity. The device comprises 128 K analog synapse and 256 neuron circuits with biologically plausible dynamics and bi-stable spike-based plasticity mechanisms that endow it with on-line learning abilities. In addition to the analog circuits, the device comprises also asynchronous digital logic circuits for setting different synapse and neuron properties as well as different network configurations. This prototype device, fabricated using a 180 nm 1P6M CMOS process, occupies an area of 51.4 mm2, and consumes approximately 4 mW for typical experiments, for example involving attractor networks. Here we describe the details of the overall architecture and of the individual circuits and present experimental results that showcase its potential. By supporting a wide range of cortical-like computational modules comprising plasticity mechanisms, this device will enable the realization of intelligent autonomous systems with on-line learning capabilities. PMID:25972778

Smart guidewires for smooth navigation in neurovascular intervention

NASA Astrophysics Data System (ADS)

Chen, Yanfei; Barry, Matthew M.; Shayan, Mahdis; Jankowitz, Brian T.; Duan, Xinjie; Robertson, Anne M.; Chyu, Minking K.; Chun, Youngjae

2015-04-01

A smart guidewire using nitinol materials was designed, manufactured and evaluated the device functionality, such as bending performance, trackability, thermal effects, and thrombogenic response. Two types of nitinol material were partially used to enhance the guidewire trackability. A proposed smart guidewire system uses either one- or two-way shape-memory alloy nitinol (1W-SMA, 2W-SMA) wires (0.015, 381µm nitinol wire). Bending stiffness was measured using in vitro test system, which contains the NI USB-9162 data logger and LabView Signal Express 2010. Temperature distribution and displacement were evaluated via recording a 60Hz movie using a SC325 camera. Hemocompatibility was evaluated by scanning electron microscopy after one heating cycle of nitinol under the Na-citrate porcine whole blood circulation. A smart guidewire showed 30 degrees bending after applying or disconnecting electrical current. While the temperature of the nitinol wires increased more than 70 °C, the surrounding temperature with the commercially available catheter coverings showed below human body temperature showing 30 ̴ 33 °C. There was no significant platelet attachment or blood coagulation when the guidewire operates. Novel smart guidewires have been developed using shape memory alloy nitinol, which may represent a novel alternative to typical commercially available guidewires for interventional procedures.

Superhydrophobic Blood-Repellent Surfaces.

PubMed

Jokinen, Ville; Kankuri, Esko; Hoshian, Sasha; Franssila, Sami; Ras, Robin H A

2018-06-01

Superhydrophobic surfaces repel water and, in some cases, other liquids as well. The repellency is caused by topographical features at the nano-/microscale and low surface energy. Blood is a challenging liquid to repel due to its high propensity for activation of intrinsic hemostatic mechanisms, induction of coagulation, and platelet activation upon contact with foreign surfaces. Imbalanced activation of coagulation drives thrombogenesis or formation of blood clots that can occlude the blood flow either on-site or further downstream as emboli, exposing tissues to ischemia and infarction. Blood-repellent superhydrophobic surfaces aim toward reducing the thrombogenicity of surfaces of blood-contacting devices and implants. Several mechanisms that lead to blood repellency are proposed, focusing mainly on platelet antiadhesion. Structured surfaces can: (i) reduce the effective area exposed to platelets, (ii) reduce the adhesion area available to individual platelets, (iii) cause hydrodynamic effects that reduce platelet adhesion, and (iv) reduce or alter protein adsorption in a way that is not conducive to thrombus formation. These mechanisms benefit from the superhydrophobic Cassie state, in which a thin layer of air is trapped between the solid surface and the liquid. The connections between water- and blood repellency are discussed and several recent examples of blood-repellent superhydrophobic surfaces are highlighted. © 2018 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hemodynamic Performance and Thrombogenic Properties of a Superhydrophobic Bileaflet Mechanical Heart Valve

PubMed Central

Bark, David L.; Vahabi, Hamed; Bui, Hieu; Movafaghi, Sanli; Moore, Brandon; Kota, Arun K.; Popat, Ketul; Dasi, Lakshmi P.

2016-01-01

In this study, we explore how blood-material interactions and hemodynamics are impacted by rendering a clinical quality 25 mm St. Jude Medical Bileaflet mechanical heart valve (BMHV) superhydrophobic (SH) with the aim of reducing thrombo-embolic complications associated with BMHVs. Basic cell adhesion is evaluated to assess blood-material interactions, while hemodynamic performance is analyzed with and without the SH coating. Results show that a SH coating with a receding contact angle (CA) of 160º strikingly eliminates platelet and leukocyte adhesion to the surface. Alternatively, many platelets attach to and activate on pyrolytic carbon (receding CA=47), the base material for BMHVs. We further show that the performance index increases by 2.5% for coated valve relative to an uncoated valve, with a maximum possible improved performance of 5%. Both valves exhibit instantaneous shear stress below 10 N/m2 and Reynolds Shear Stress below 100 N/m2. Therefore, a SH BMHV has the potential to relax the requirement for antiplatelet and anticoagulant drug regimens typically required for patients receiving MHVs by minimizing blood-material interactions, while having a minimal impact on hemodynamics. We show for the first time that SH-coated surfaces may be a promising direction to minimize thrombotic complications in complex devices such as heart valves. PMID:27098219

Correction of microplate location effects improves performance of the thrombin generation test

PubMed Central

2013-01-01

Background Microplate-based thrombin generation test (TGT) is widely used as clinical measure of global hemostatic potential and it becomes a useful tool for control of drug potency and quality by drug manufactures. However, the convenience of the microtiter plate technology can be deceiving: microplate assays are prone to location-based variability in different parts of the microtiter plate. Methods In this report, we evaluated the well-to-well consistency of the TGT variant specifically applied to the quantitative detection of the thrombogenic substances in the immune globulin product. We also studied the utility of previously described microplate layout designs in the TGT experiment. Results Location of the sample on the microplate (location effect) contributes to the variability of TGT measurements. Use of manual pipetting techniques and applications of the TGT to the evaluation of procoagulant enzymatic substances are especially sensitive. The effects were not sensitive to temperature or choice of microplate reader. Smallest location effects were observed with automated dispenser-based calibrated thrombogram instrument. Even for an automated instrument, the use of calibration curve resulted in up to 30% bias in thrombogenic potency assignment. Conclusions Use of symmetrical version of the strip-plot layout was demonstrated to help to minimize location artifacts even under the worst-case conditions. Strip-plot layouts are required for quantitative thrombin-generation based bioassays used in the biotechnological field. PMID:23829491

Correction of microplate location effects improves performance of the thrombin generation test.

PubMed

Liang, Yideng; Woodle, Samuel A; Shibeko, Alexey M; Lee, Timothy K; Ovanesov, Mikhail V

2013-07-05

Microplate-based thrombin generation test (TGT) is widely used as clinical measure of global hemostatic potential and it becomes a useful tool for control of drug potency and quality by drug manufactures. However, the convenience of the microtiter plate technology can be deceiving: microplate assays are prone to location-based variability in different parts of the microtiter plate. In this report, we evaluated the well-to-well consistency of the TGT variant specifically applied to the quantitative detection of the thrombogenic substances in the immune globulin product. We also studied the utility of previously described microplate layout designs in the TGT experiment. Location of the sample on the microplate (location effect) contributes to the variability of TGT measurements. Use of manual pipetting techniques and applications of the TGT to the evaluation of procoagulant enzymatic substances are especially sensitive. The effects were not sensitive to temperature or choice of microplate reader. Smallest location effects were observed with automated dispenser-based calibrated thrombogram instrument. Even for an automated instrument, the use of calibration curve resulted in up to 30% bias in thrombogenic potency assignment. Use of symmetrical version of the strip-plot layout was demonstrated to help to minimize location artifacts even under the worst-case conditions. Strip-plot layouts are required for quantitative thrombin-generation based bioassays used in the biotechnological field.

Nonthrombogenic, biodegradable elastomeric polyurethanes with variable sulfobetaine content.

PubMed

Ye, Sang-Ho; Hong, Yi; Sakaguchi, Hirokazu; Shankarraman, Venkat; Luketich, Samuel K; D'Amore, Antonio; Wagner, William R

2014-12-24

For applications where degradable polymers are likely to have extended blood contact, it is often important for these materials to exhibit high levels of thromboresistance. This can be achieved with surface modification approaches, but such modifications may be transient with degradation. Alternatively, polymer design can be altered such that the bulk polymer is thromboresistant and this is maintained with degradation. Toward this end a series of biodegradable, elastic polyurethanes (PESBUUs) containing different zwitterionic sulfobetaine (SB) content were synthesized from a polycaprolactone-diol (PCL-diol):SB-diol mixture (100:0, 75:25, 50:50, 25:75 and 0:100) reacted with diisocyanatobutane and chain extended with putrescine. The chemical structure, tensile mechanical properties, thermal properties, hydrophilicity, biodegradability, fibrinogen adsorption and thrombogenicity of the resulting polymers was characterized. With increased SB content some weakening in tensile properties occurred in wet conditions and enzymatic degradation also decreased. However, at higher zwitterionic molar ratios (50% and 75%) wet tensile strength exceeded 15 MPa and breaking strain was >500%. Markedly reduced thrombotic deposition was observed both before and after substantial degradation for both of these PESBUUs and they could be processed by electrospinning into a vascular conduit format with appropriate compliance properties. The mechanical and degradation properties as well as the acute in vitro thrombogenicity assessment suggest that these tunable polyurethanes could provide options appropriate for use in blood contacting applications where a degradable, elastomeric component with enduring thromboresistance is desired.

Heparin conjugated quantum dots for in vitro imaging applications.

PubMed

Maguire, Ciaran Manus; Mahfoud, Omar Kazem; Rakovich, Tatsiana; Gerard, Valerie Anne; Prina-Mello, Adriele; Gun'ko, Yurii; Volkov, Yuri

2014-11-01

In this work heparin-gelatine multi-layered cadmium telluride quantum dots (QDgel/hep) were synthesised using a novel 'one-pot' method. The QDs produced were characterised using various spectroscopic and physiochemical techniques. Suitable QDs were then selected and compared to thioglycolic acid stabilised quantum dots (QDTGA) and gelatine coated quantum dots (QDgel) for utilisation in in vitro imaging experiments on live and fixed permeabilised THP-1, A549 and Caco-2 cell lines. Exposure of live THP-1 cells to QDgel/hep resulted in localisation of the QDs to the nucleus of the cells. QDgel/hep show affinity for the nuclear compartment of fixed permeabilised THP-1 and A549 cells but remain confined to cytoplasm of fixed permeabilised Caco-2 cells. It is postulated that heparin binding to the CD11b receptor facilitates the internalisation of the QDs into the nucleus of THP-1 cells. In addition, the heparin layer may reduce the unfavourable thrombogenic nature of quantum dots observed in vivo. In this study, heparin conjugated quantum dots were found to have superior imaging properties compared to its native counterparts. The authors postulate that heparin binding to the CD11b receptor facilitates QD internalization to the nucleus, and the heparin layer may reduce the in vivo thrombogenic properties of quantum dots. Copyright © 2014 Elsevier Inc. All rights reserved.

ABO blood groups: A risk factor for left atrial and left atrial appendage thrombogenic milieu in patients with non-valvular atrial fibrillation.

PubMed

Fu, Yuan; Li, Kuibao; Yang, Xinchun

2017-08-01

Previous studies have identified ABO blood groups as predictors of thromboembolic diseases. In patients with atrial fibrillation (AF), however, potential association between ABO blood groups and the risk of left atrial (LA) and/or left atrial appendage (LAA) thrombogenic milieu (TM) has not been established. This is a retrospective case-control study that included 125 consecutive patients with non-valvular atrial fibrillation (NVAF) plus TM, as evidenced by transesophageal echocardiography (TEE) during a period from1 January 2010 to 31 December 2016. The controls were selected randomly from 1072 NVAF without TM at a 1:2 ratio. Potential association between ABO blood groups and TM was analyzed using multivariate logistic regression analysis. The risk of TM was higher in patients with blood group A (33.6% vs. 20.2% in non-A blood groups, P=0.005). After adjusting for age, sex, oral anticoagulant use, AF type and duration, and relevant functional measures (e.g., NT-pro BNP level, left atrium diameter, and left ventricular ejection fraction), blood group A remained associated with an increased risk of TM (OR=2.99, 95% CI 1.4-6.388, P=0.005). Blood group A is an independent risk factor for TM in NVAF patients. Copyright © 2017 Elsevier Ltd. All rights reserved.

Continuous-variable quantum authentication of physical unclonable keys: Security against an emulation attack

NASA Astrophysics Data System (ADS)

Nikolopoulos, Georgios M.

2018-01-01

We consider a recently proposed entity authentication protocol in which a physical unclonable key is interrogated by random coherent states of light, and the quadratures of the scattered light are analyzed by means of a coarse-grained homodyne detection. We derive a sufficient condition for the protocol to be secure against an emulation attack in which an adversary knows the challenge-response properties of the key and moreover, he can access the challenges during the verification. The security analysis relies on Holevo's bound and Fano's inequality, and suggests that the protocol is secure against the emulation attack for a broad range of physical parameters that are within reach of today's technology.

A polymorphic reconfigurable emulator for parallel simulation

NASA Technical Reports Server (NTRS)

Parrish, E. A., Jr.; Mcvey, E. S.; Cook, G.

1980-01-01

Microprocessor and arithmetic support chip technology was applied to the design of a reconfigurable emulator for real time flight simulation. The system developed consists of master control system to perform all man machine interactions and to configure the hardware to emulate a given aircraft, and numerous slave compute modules (SCM) which comprise the parallel computational units. It is shown that all parts of the state equations can be worked on simultaneously but that the algebraic equations cannot (unless they are slowly varying). Attempts to obtain algorithms that will allow parellel updates are reported. The word length and step size to be used in the SCM's is determined and the architecture of the hardware and software is described.

EDT mode for JED -- An advanced Unix text editor

NASA Astrophysics Data System (ADS)

McIlwrath, B. K.; Page, C. G.

This note describes Starlink extended EDT emulation for the JED editor. It provides a Unix text editor which can utilise the advanced facilities of DEC VTn00, xterm and similar terminals. JED in this mode provides a reasonably good emulation of the VAX/VMS editor EDT in addition to many extra facilities.

Using Texas Instruments Emulators as Teaching Tools in Quantitative Chemical Analysis

ERIC Educational Resources Information Center

Young, Vaneica Y.

2011-01-01

This technology report alerts upper-division undergraduate chemistry faculty and lecturers to the use of Texas Instruments emulators as virtual graphing calculators. These may be used in multimedia lectures to instruct students on the use of their graphing calculators to obtain solutions to complex chemical problems. (Contains 1 figure.)

Emulation of reionization simulations for Bayesian inference of astrophysics parameters using neural networks

NASA Astrophysics Data System (ADS)

Schmit, C. J.; Pritchard, J. R.

2018-03-01

Next generation radio experiments such as LOFAR, HERA, and SKA are expected to probe the Epoch of Reionization (EoR) and claim a first direct detection of the cosmic 21cm signal within the next decade. Data volumes will be enormous and can thus potentially revolutionize our understanding of the early Universe and galaxy formation. However, numerical modelling of the EoR can be prohibitively expensive for Bayesian parameter inference and how to optimally extract information from incoming data is currently unclear. Emulation techniques for fast model evaluations have recently been proposed as a way to bypass costly simulations. We consider the use of artificial neural networks as a blind emulation technique. We study the impact of training duration and training set size on the quality of the network prediction and the resulting best-fitting values of a parameter search. A direct comparison is drawn between our emulation technique and an equivalent analysis using 21CMMC. We find good predictive capabilities of our network using training sets of as low as 100 model evaluations, which is within the capabilities of fully numerical radiative transfer codes.

A Novel Approach for Determining Source–Receptor Relationships in Model Simulations: A Case Study of Black Carbon Transport in Northern Hemisphere Winter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Po-Lun; Gattiker, J. R.; Liu, Xiaohong

2013-06-27

A Gaussian process (GP) emulator is applied to quantify the contribution of local and remote emissions of black carbon (BC) on the BC concentrations in different regions using a Latin Hypercube sampling strategy for emission perturbations in the offline version of the Community Atmosphere Model Version 5.1 (CAM5) simulations. The source-receptor relationships are computed based on simulations constrained by a standard free-running CAM5 simulation and the ERA-Interim reanalysis product. The analysis demonstrates that the emulator is capable of retrieving the source-receptor relationships based on a small number of CAM5 simulations. Most regions are found susceptible to their local emissions. Themore » emulator also finds that the source-receptor relationships retrieved from the model-driven and the reanalysis-driven simulations are very similar, suggesting that the simulated circulation in CAM5 resembles the assimilated meteorology in ERA-Interim. The robustness of the results provides confidence for applying the emulator to detect dose-response signals in the climate system.« less

Double-Barrier Memristive Devices for Unsupervised Learning and Pattern Recognition.

PubMed

Hansen, Mirko; Zahari, Finn; Ziegler, Martin; Kohlstedt, Hermann

2017-01-01

The use of interface-based resistive switching devices for neuromorphic computing is investigated. In a combined experimental and numerical study, the important device parameters and their impact on a neuromorphic pattern recognition system are studied. The memristive cells consist of a layer sequence Al/Al 2 O 3 /Nb x O y /Au and are fabricated on a 4-inch wafer. The key functional ingredients of the devices are a 1.3 nm thick Al 2 O 3 tunnel barrier and a 2.5 mm thick Nb x O y memristive layer. Voltage pulse measurements are used to study the electrical conditions for the emulation of synaptic functionality of single cells for later use in a recognition system. The results are evaluated and modeled in the framework of the plasticity model of Ziegler et al. Based on this model, which is matched to experimental data from 84 individual devices, the network performance with regard to yield, reliability, and variability is investigated numerically. As the network model, a computing scheme for pattern recognition and unsupervised learning based on the work of Querlioz et al. (2011), Sheridan et al. (2014), Zahari et al. (2015) is employed. This is a two-layer feedforward network with a crossbar array of memristive devices, leaky integrate-and-fire output neurons including a winner-takes-all strategy, and a stochastic coding scheme for the input pattern. As input pattern, the full data set of digits from the MNIST database is used. The numerical investigation indicates that the experimentally obtained yield, reliability, and variability of the memristive cells are suitable for such a network. Furthermore, evidence is presented that their strong I - V non-linearity might avoid the need for selector devices in crossbar array structures.

A Novel Device for Grasping Assessment during Functional Tasks: Preliminary Results

PubMed Central

Rocha, Ana Carolinne Portela; Tudella, Eloisa; Pedro, Leonardo M.; Appel, Viviane Cristina Roma; da Silva, Louise Gracelli Pereira; Caurin, Glauco Augusto de Paula

2016-01-01

This paper presents a methodology and first results obtained in a study with a novel device that allows the analysis of grasping quality. Such a device is able to acquire motion information of upper limbs allowing kinetic of manipulation analysis as well. A pilot experiment was carried out with six groups of typically developing children aged between 5 and 10 years, with seven to eight children in each one. The device, designed to emulate a glass, has an optical system composed by one digital camera and a special convex mirror that together allow image acquisition of grasping hand posture when it is grasped and manipulated. It also carries an Inertial Measurement Unit that captures motion data as acceleration, orientation, and angular velocities. The novel instrumented object is used in our approach to evaluate functional tasks performance in quantitative terms. During tests, each child was invited to grasp the cylindrical part of the device that was placed on the top of a table, simulating the task of drinking a glass of water. In the sequence, the child was oriented to transport the device back to the starting position and release it. The task was repeated three times for each child. A grasping hand posture evaluation is presented as an example to evaluate grasping quality. Additionally, motion patterns obtained with the trials performed with the different groups are presented and discussed. This device is attractive due to its portable characteristics, the small size, and its ability to evaluate grasping form. The results may be also useful to analyze the evolution of the rehabilitation process through reach-to-grasping movement and the grasping images analysis. PMID:26942178

Feasibility and reliability of using an exoskeleton to emulate muscle contractures during walking.

PubMed

Attias, M; Bonnefoy-Mazure, A; De Coulon, G; Cheze, L; Armand, S

2016-10-01

Contracture is a permanent shortening of the muscle-tendon-ligament complex that limits joint mobility. Contracture is involved in many diseases (cerebral palsy, stroke, etc.) and can impair walking and other activities of daily living. The purpose of this study was to quantify the reliability of an exoskeleton designed to emulate lower limb muscle contractures unilaterally and bilaterally during walking. An exoskeleton was built according to the following design criteria: adjustable to different morphologies; respect of the principal lines of muscular actions; placement of reflective markers on anatomical landmarks; and the ability to replicate the contractures of eight muscles of the lower limb unilaterally and bilaterally (psoas, rectus femoris, hamstring, hip adductors, gastrocnemius, soleus, tibialis posterior, and peroneus). Sixteen combinations of contractures were emulated on the unilateral and bilateral muscles of nine healthy participants. Two sessions of gait analysis were performed at weekly intervals to assess the reliability of the emulated contractures. Discrete variables were extracted from the kinematics to analyse the reliability. The exoskeleton did not affect normal walking when contractures were not emulated. Kinematic reliability varied from poor to excellent depending on the targeted muscle. Reliability was good for the bilateral and unilateral gastrocnemius, soleus, and tibialis posterior as well as the bilateral hamstring and unilateral hip adductors. The exoskeleton can be used to replicate contracture on healthy participants. The exoskeleton will allow us to differentiate primary and compensatory effects of muscle contractures on gait kinematics. Copyright © 2016 Elsevier B.V. All rights reserved.

Fast and Precise Emulation of Stochastic Biochemical Reaction Networks With Amplified Thermal Noise in Silicon Chips.

PubMed

Kim, Jaewook; Woo, Sung Sik; Sarpeshkar, Rahul

2018-04-01

The analysis and simulation of complex interacting biochemical reaction pathways in cells is important in all of systems biology and medicine. Yet, the dynamics of even a modest number of noisy or stochastic coupled biochemical reactions is extremely time consuming to simulate. In large part, this is because of the expensive cost of random number and Poisson process generation and the presence of stiff, coupled, nonlinear differential equations. Here, we demonstrate that we can amplify inherent thermal noise in chips to emulate randomness physically, thus alleviating these costs significantly. Concurrently, molecular flux in thermodynamic biochemical reactions maps to thermodynamic electronic current in a transistor such that stiff nonlinear biochemical differential equations are emulated exactly in compact, digitally programmable, highly parallel analog "cytomorphic" transistor circuits. For even small-scale systems involving just 80 stochastic reactions, our 0.35-μm BiCMOS chips yield a 311× speedup in the simulation time of Gillespie's stochastic algorithm over COPASI, a fast biochemical-reaction software simulator that is widely used in computational biology; they yield a 15 500× speedup over equivalent MATLAB stochastic simulations. The chip emulation results are consistent with these software simulations over a large range of signal-to-noise ratios. Most importantly, our physical emulation of Poisson chemical dynamics does not involve any inherently sequential processes and updates such that, unlike prior exact simulation approaches, they are parallelizable, asynchronous, and enable even more speedup for larger-size networks.

An aerosol activation metamodel of v1.2.0 of the pyrcel cloud parcel model: development and offline assessment for use in an aerosol–climate model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rothenberg, Daniel; Wang, Chien

We describe an emulator of a detailed cloud parcel model which has been trained to assess droplet nucleation from a complex, multimodal aerosol size distribution simulated by a global aerosol–climate model. The emulator is constructed using a sensitivity analysis approach (polynomial chaos expansion) which reproduces the behavior of the targeted parcel model across the full range of aerosol properties and meteorology simulated by the parent climate model. An iterative technique using aerosol fields sampled from a global model is used to identify the critical aerosol size distribution parameters necessary for accurately predicting activation. Across the large parameter space used tomore » train them, the emulators estimate cloud droplet number concentration (CDNC) with a mean relative error of 9.2% for aerosol populations without giant cloud condensation nuclei (CCN) and 6.9% when including them. Versus a parcel model driven by those same aerosol fields, the best-performing emulator has a mean relative error of 4.6%, which is comparable with two commonly used activation schemes also evaluated here (which have mean relative errors of 2.9 and 6.7%, respectively). We identify the potential for regional biases in modeled CDNC, particularly in oceanic regimes, where our best-performing emulator tends to overpredict by 7%, whereas the reference activation schemes range in mean relative error from -3 to 7%. The emulators which include the effects of giant CCN are more accurate in continental regimes (mean relative error of 0.3%) but strongly overestimate CDNC in oceanic regimes by up to 22%, particularly in the Southern Ocean. Finally, the biases in CDNC resulting from the subjective choice of activation scheme could potentially influence the magnitude of the indirect effect diagnosed from the model incorporating it.« less

An aerosol activation metamodel of v1.2.0 of the pyrcel cloud parcel model: development and offline assessment for use in an aerosol–climate model

DOE PAGES

Rothenberg, Daniel; Wang, Chien

2017-04-27

We describe an emulator of a detailed cloud parcel model which has been trained to assess droplet nucleation from a complex, multimodal aerosol size distribution simulated by a global aerosol–climate model. The emulator is constructed using a sensitivity analysis approach (polynomial chaos expansion) which reproduces the behavior of the targeted parcel model across the full range of aerosol properties and meteorology simulated by the parent climate model. An iterative technique using aerosol fields sampled from a global model is used to identify the critical aerosol size distribution parameters necessary for accurately predicting activation. Across the large parameter space used tomore » train them, the emulators estimate cloud droplet number concentration (CDNC) with a mean relative error of 9.2% for aerosol populations without giant cloud condensation nuclei (CCN) and 6.9% when including them. Versus a parcel model driven by those same aerosol fields, the best-performing emulator has a mean relative error of 4.6%, which is comparable with two commonly used activation schemes also evaluated here (which have mean relative errors of 2.9 and 6.7%, respectively). We identify the potential for regional biases in modeled CDNC, particularly in oceanic regimes, where our best-performing emulator tends to overpredict by 7%, whereas the reference activation schemes range in mean relative error from -3 to 7%. The emulators which include the effects of giant CCN are more accurate in continental regimes (mean relative error of 0.3%) but strongly overestimate CDNC in oceanic regimes by up to 22%, particularly in the Southern Ocean. Finally, the biases in CDNC resulting from the subjective choice of activation scheme could potentially influence the magnitude of the indirect effect diagnosed from the model incorporating it.« less

Real-Time Observation of Thrombus Growth Process in an Impeller of a Hydrodynamically Levitated Centrifugal Blood Pump by Near-Infrared Hyperspectral Imaging.

PubMed

Sakota, Daisuke; Murashige, Tomotaka; Kosaka, Ryo; Fujiwara, Tatsuki; Nishida, Masahiro; Maruyama, Osamu

2015-08-01

Understanding the thrombus formation in cardiovascular devices such as rotary blood pumps is the most important issue in developing more hemocompatible devices. The objective of this study was to develop a hyperspectral imaging (HSI) method to visualize the thrombus growth process within a rotary blood pump and investigate the optical properties of the thrombus. An in vitro thrombogenic test was conducted using fresh porcine blood and a specially designed hydrodynamically levitated centrifugal blood pump with a transparent bottom. The pump rotating at 3000 rpm circulated the blood at 1.0 L/min. The bottom surface of the pump was illuminated with white light pulsed at the same frequency as the pump rotation, and the backward-scattered light was imaged using the HSI system. Using stroboscopic HSI and an image construction algorithm, dynamic spectral imaging at wavelengths ranging from 608 to 752 nm within the rotating pump was achieved. After completing the experiment, we collected the red thrombus formed in the pump impeller and quantified the thrombus hemoglobin concentration (Hbthrombus ). The spectrum changed around the center of the impeller, and the area of change expanded toward the impeller flow path. The shape corresponded approximately to the shape of the thrombus. The spectrum change indicated that the light scattering derived from red blood cells decreased. The Hbthrombus was 4.7 ± 1.3 g/dL versus a total hemoglobin of 13 ± 0.87 g/dL. The study revealed that Hbthrombus was reduced by the surrounding blood flow. Copyright © 2015 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Microswitch and Keyboard-Emulator Technology to Facilitate the Writing Performance of Persons with Extensive Motor Disabilities

ERIC Educational Resources Information Center

Lancioni, Giulio E.; Singh, Nirbhay N.; O'Reilly, Mark F.; Sigafoos, Jeff; Green, Vanessa; Oliva, Doretta; Lang, Russell

2011-01-01

This study assessed the effectiveness of microswitches for simple responses (i.e., partial hand closure, vocalization, and hand stroking) and a keyboard emulator to facilitate the writing performance of three participants with extensive motor disabilities. The study was carried out according to an ABAB design. During the A phases, the participants…

Development of the CELSS emulator at NASA. Johnson Space Center

NASA Technical Reports Server (NTRS)

Cullingford, Hatice S.

1990-01-01

The Closed Ecological Life Support System (CELSS) Emulator is under development. It will be used to investigate computer simulations of integrated CELSS operations involving humans, plants, and process machinery. Described here is Version 1.0 of the CELSS Emulator that was initiated in 1988 on the Johnson Space Center (JSC) Multi Purpose Applications Console Test Bed as the simulation framework. The run model of the simulation system now contains a CELSS model called BLSS. The CELSS simulator empowers us to generate model data sets, store libraries of results for further analysis, and also display plots of model variables as a function of time. The progress of the project is presented with sample test runs and simulation display pages.

A memristive plasticity model of voltage-based STDP suitable for recurrent bidirectional neural networks in the hippocampus.

PubMed

Diederich, Nick; Bartsch, Thorsten; Kohlstedt, Hermann; Ziegler, Martin

2018-06-19

Memristive systems have gained considerable attention in the field of neuromorphic engineering, because they allow the emulation of synaptic functionality in solid state nano-physical systems. In this study, we show that memristive behavior provides a broad working framework for the phenomenological modelling of cellular synaptic mechanisms. In particular, we seek to understand how close a memristive system can account for the biological realism. The basic characteristics of memristive systems, i.e. voltage and memory behavior, are used to derive a voltage-based plasticity rule. We show that this model is suitable to account for a variety of electrophysiology plasticity data. Furthermore, we incorporate the plasticity model into an all-to-all connecting network scheme. Motivated by the auto-associative CA3 network of the hippocampus, we show that the implemented network allows the discrimination and processing of mnemonic pattern information, i.e. the formation of functional bidirectional connections resulting in the formation of local receptive fields. Since the presented plasticity model can be applied to real memristive devices as well, the presented theoretical framework can support both, the design of appropriate memristive devices for neuromorphic computing and the development of complex neuromorphic networks, which account for the specific advantage of memristive devices.

Development of a Detailed Volumetric Finite Element Model of the Spine to Simulate Surgical Correction of Spinal Deformities

PubMed Central

Driscoll, Mark; Mac-Thiong, Jean-Marc; Labelle, Hubert; Parent, Stefan

2013-01-01

A large spectrum of medical devices exists; it aims to correct deformities associated with spinal disorders. The development of a detailed volumetric finite element model of the osteoligamentous spine would serve as a valuable tool to assess, compare, and optimize spinal devices. Thus the purpose of the study was to develop and initiate validation of a detailed osteoligamentous finite element model of the spine with simulated correction from spinal instrumentation. A finite element of the spine from T1 to L5 was developed using properties and geometry from the published literature and patient data. Spinal instrumentation, consisting of segmental translation of a scoliotic spine, was emulated. Postoperative patient and relevant published data of intervertebral disc stress, screw/vertebra pullout forces, and spinal profiles was used to evaluate the models validity. Intervertebral disc and vertebral reaction stresses respected published in vivo, ex vivo, and in silico values. Screw/vertebra reaction forces agreed with accepted pullout threshold values. Cobb angle measurements of spinal deformity following simulated surgical instrumentation corroborated with patient data. This computational biomechanical analysis validated a detailed volumetric spine model. Future studies seek to exploit the model to explore the performance of corrective spinal devices. PMID:23991426

A Physical Heart Failure Simulation System Utilizing the Total Artificial Heart and Modified Donovan Mock Circulation.

PubMed

Crosby, Jessica R; DeCook, Katrina J; Tran, Phat L; Betterton, Edward; Smith, Richard G; Larson, Douglas F; Khalpey, Zain I; Burkhoff, Daniel; Slepian, Marvin J

2017-07-01

With the growth and diversity of mechanical circulatory support (MCS) systems entering clinical use, a need exists for a robust mock circulation system capable of reliably emulating and reproducing physiologic as well as pathophysiologic states for use in MCS training and inter-device comparison. We report on the development of such a platform utilizing the SynCardia Total Artificial Heart and a modified Donovan Mock Circulation System, capable of being driven at normal and reduced output. With this platform, clinically relevant heart failure hemodynamics could be reliably reproduced as evidenced by elevated left atrial pressure (+112%), reduced aortic flow (-12.6%), blunted Starling-like behavior, and increased afterload sensitivity when compared with normal function. Similarly, pressure-volume relationships demonstrated enhanced sensitivity to afterload and decreased Starling-like behavior in the heart failure model. Lastly, the platform was configured to allow the easy addition of a left ventricular assist device (HeartMate II at 9600 RPM), which upon insertion resulted in improvement of hemodynamics. The present configuration has the potential to serve as a viable system for training and research, aimed at fostering safe and effective MCS device use. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Experimental Determination of Demand Response Control Models and Cost of Control for Ensembles of Window-Mount Air Conditioners

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geller, Drew Adam; Backhaus, Scott N.

Control of consumer electrical devices for providing electrical grid services is expanding in both the scope and the diversity of loads that are engaged in control, but there are few experimentally-based models of these devices suitable for control designs and for assessing the cost of control. A laboratory-scale test system is developed to experimentally evaluate the use of a simple window-mount air conditioner for electrical grid regulation services. The experimental test bed is a single, isolated air conditioner embedded in a test system that both emulates the thermodynamics of an air conditioned room and also isolates the air conditioner frommore » the real-world external environmental and human variables that perturb the careful measurements required to capture a model that fully characterizes both the control response functions and the cost of control. The control response functions and cost of control are measured using harmonic perturbation of the temperature set point and a test protocol that further isolates the air conditioner from low frequency environmental variability.« less

A new DG nanoscale TFET based on MOSFETs by using source gate electrode: 2D simulation and an analytical potential model

NASA Astrophysics Data System (ADS)

Ramezani, Zeinab; Orouji, Ali A.

2017-08-01

This paper suggests and investigates a double-gate (DG) MOSFET, which emulates tunnel field effect transistors (M-TFET). We have combined this novel concept into a double-gate MOSFET, which behaves as a tunneling field effect transistor by work function engineering. In the proposed structure, in addition to the main gate, we utilize another gate over the source region with zero applied voltage and a proper work function to convert the source region from N+ to P+. We check the impact obtained by varying the source gate work function and source doping on the device parameters. The simulation results of the M-TFET indicate that it is a suitable case for a switching performance. Also, we present a two-dimensional analytic potential model of the proposed structure by solving the Poisson's equation in x and y directions and by derivatives from the potential profile; thus, the electric field is achieved. To validate our present model, we use the SILVACO ATLAS device simulator. The analytical results have been compared with it.

Neuro-prosthetic interplay. Comment on "Hand synergies: Integration of robotics and neuroscience for understanding the control of biological and artificial hands" by M. Santello et al.

NASA Astrophysics Data System (ADS)

Schieber, Marc H.

2016-07-01

Control of the human hand has been both difficult to understand scientifically and difficult to emulate technologically. The article by Santello and colleagues in the current issue of Physics of Life Reviews[1] highlights the accelerating pace of interaction between the neuroscience of controlling body movement and the engineering of robotic hands that can be used either autonomously or as part of a motor neuroprosthesis, an artificial body part that moves under control from a human subject's own nervous system. Motor neuroprostheses typically involve a brain-computer interface (BCI) that takes signals from the subject's nervous system or muscles, interprets those signals through a decoding algorithm, and then applies the resulting output to control the artificial device.

Directed liquid phase assembly of highly ordered metallic nanoparticle arrays

DOE PAGES

Wu, Yueying; Dong, Nanyi; Fu, Shaofang; ...

2014-04-01

Directed assembly of nanomaterials is a promising route for the synthesis of advanced materials and devices. We demonstrate the directed-assembly of highly ordered two-dimensional arrays of hierarchical nanostructures with tunable size, spacing and composition. The directed assembly is achieved on lithographically patterned metal films that are subsequently pulse-laser melted; during the brief liquid lifetime, the pattened nanostructures assemble into highly ordered primary and secondary nanoparticles, with sizes below that which was originally patterned. Complementary fluid-dynamics simulations emulate the resultant patterns and show how the competition of capillary forces and liquid metal–solid substrate interaction potential drives the directed assembly. Lastly, asmore » an example of the enhanced functionality, a full-wave electromagnetic analysis has been performed to identify the nature of the supported plasmonic resonances.« less

APRON: A Cellular Processor Array Simulation and Hardware Design Tool

NASA Astrophysics Data System (ADS)

Barr, David R. W.; Dudek, Piotr

2009-12-01

We present a software environment for the efficient simulation of cellular processor arrays (CPAs). This software (APRON) is used to explore algorithms that are designed for massively parallel fine-grained processor arrays, topographic multilayer neural networks, vision chips with SIMD processor arrays, and related architectures. The software uses a highly optimised core combined with a flexible compiler to provide the user with tools for the design of new processor array hardware architectures and the emulation of existing devices. We present performance benchmarks for the software processor array implemented on standard commodity microprocessors. APRON can be configured to use additional processing hardware if necessary and can be used as a complete graphical user interface and development environment for new or existing CPA systems, allowing more users to develop algorithms for CPA systems.

PyGirl: Generating Whole-System VMs from High-Level Prototypes Using PyPy

NASA Astrophysics Data System (ADS)

Bruni, Camillo; Verwaest, Toon

Virtual machines (VMs) emulating hardware devices are generally implemented in low-level languages for performance reasons. This results in unmaintainable systems that are difficult to understand. In this paper we report on our experience using the PyPy toolchain to improve the portability and reduce the complexity of whole-system VM implementations. As a case study we implement a VM prototype for a Nintendo Game Boy, called PyGirl, in which the high-level model is separated from low-level VM implementation issues. We shed light on the process of refactoring from a low-level VM implementation in Java to a high-level model in RPython. We show that our whole-system VM written with PyPy is significantly less complex than standard implementations, without substantial loss in performance.

Mechanically triggered heterolytic unzipping of a low-ceiling-temperature polymer

NASA Astrophysics Data System (ADS)

Diesendruck, Charles E.; Peterson, Gregory I.; Kulik, Heather J.; Kaitz, Joshua A.; Mar, Brendan D.; May, Preston A.; White, Scott R.; Martínez, Todd J.; Boydston, Andrew J.; Moore, Jeffrey S.

2014-07-01

Biological systems rely on recyclable materials resources such as amino acids, carbohydrates and nucleic acids. When biomaterials are damaged as a result of aging or stress, tissues undergo repair by a depolymerization-repolymerization sequence of remodelling. Integration of this concept into synthetic materials systems may lead to devices with extended lifetimes. Here, we show that a metastable polymer, end-capped poly(o-phthalaldehyde), undergoes mechanically initiated depolymerization to revert the material to monomers. Trapping experiments and steered molecular dynamics simulations are consistent with a heterolytic scission mechanism. The obtained monomer was repolymerized by a chemical initiator, effectively completing a depolymerization-repolymerization cycle. By emulating remodelling of biomaterials, this model system suggests the possibility of smart materials where aging or mechanical damage triggers depolymerization, and orthogonal conditions regenerate the polymer when and where necessary.

Fast-responding liquid crystal light-valve technology for color-sequential display applications

NASA Astrophysics Data System (ADS)

Janssen, Peter J.; Konovalov, Victor A.; Muravski, Anatoli A.; Yakovenko, Sergei Y.

1996-04-01

A color sequential projection system has some distinct advantages over conventional systems which make it uniquely suitable for consumer TV as well as high performance professional applications such as computer monitors and electronic cinema. A fast responding light-valve is, clearly, essential for a good performing system. Response speed of transmissive LC lightvalves has been marginal thus far for good color rendition. Recently, Sevchenko Institute has made some very fast reflective LC cells which were evaluated at Philips Labs. These devices showed sub millisecond-large signal-response times, even at room temperature, and produced good color in a projector emulation testbed. In our presentation we describe our highly efficient color sequential projector and demonstrate its operation on video tape. Next we discuss light-valve requirements and reflective light-valve test results.

Are biochips the new wave

NASA Astrophysics Data System (ADS)

Bussert, J.

1982-06-01

The possibility of microchip synthesis from molecular configurations is considered. A bistable memory element concept is described which can be independently written on and read, and which consists of a chain of transition metal atoms, a bulging ligand connecting the transition metal atoms, and two types of ligand attached to the transition metal atoms. The molecular emulation of switches, memory and interfaces is presently being investigated independently, although simultaneous synthesis of entire architectures is the ultimate goal of research. Molecular circuitry, which could incorporate 10,000 more gates into an IC chip than chemical techniques, would be of greatest immediate importance in avionics and other portable military electronics devices for which minimum size and weight are valuable. Attention is given to a computer-controlled method for the synthesis of molecular computers.

HTM Spatial Pooler With Memristor Crossbar Circuits for Sparse Biometric Recognition.

PubMed

James, Alex Pappachen; Fedorova, Irina; Ibrayev, Timur; Kudithipudi, Dhireesha

2017-06-01

Hierarchical Temporal Memory (HTM) is an online machine learning algorithm that emulates the neo-cortex. The development of a scalable on-chip HTM architecture is an open research area. The two core substructures of HTM are spatial pooler and temporal memory. In this work, we propose a new Spatial Pooler circuit design with parallel memristive crossbar arrays for the 2D columns. The proposed design was validated on two different benchmark datasets, face recognition, and speech recognition. The circuits are simulated and analyzed using a practical memristor device model and 0.18 μm IBM CMOS technology model. The databases AR, YALE, ORL, and UFI, are used to test the performance of the design in face recognition. TIMIT dataset is used for the speech recognition.

Yielding physically-interpretable emulators - A Sparse PCA approach

NASA Astrophysics Data System (ADS)

Galelli, S.; Alsahaf, A.; Giuliani, M.; Castelletti, A.

2015-12-01

Projection-based techniques, such as Principal Orthogonal Decomposition (POD), are a common approach to surrogate high-fidelity process-based models by lower order dynamic emulators. With POD, the dimensionality reduction is achieved by using observations, or 'snapshots' - generated with the high-fidelity model -, to project the entire set of input and state variables of this model onto a smaller set of basis functions that account for most of the variability in the data. While reduction efficiency and variance control of POD techniques are usually very high, the resulting emulators are structurally highly complex and can hardly be given a physically meaningful interpretation as each basis is a projection of the entire set of inputs and states. In this work, we propose a novel approach based on Sparse Principal Component Analysis (SPCA) that combines the several assets of POD methods with the potential for ex-post interpretation of the emulator structure. SPCA reduces the number of non-zero coefficients in the basis functions by identifying a sparse matrix of coefficients. While the resulting set of basis functions may retain less variance of the snapshots, the presence of a few non-zero coefficients assists in the interpretation of the underlying physical processes. The SPCA approach is tested on the reduction of a 1D hydro-ecological model (DYRESM-CAEDYM) used to describe the main ecological and hydrodynamic processes in Tono Dam, Japan. An experimental comparison against a standard POD approach shows that SPCA achieves the same accuracy in emulating a given output variable - for the same level of dimensionality reduction - while yielding better insights of the main process dynamics.

Assessment of phase based dose modulation for improved dose efficiency in cardiac CT on an anthropomorphic motion phantom

NASA Astrophysics Data System (ADS)

Budde, Adam; Nilsen, Roy; Nett, Brian

2014-03-01

State of the art automatic exposure control modulates the tube current across view angle and Z based on patient anatomy for use in axial full scan reconstructions. Cardiac CT, however, uses a fundamentally different image reconstruction that applies a temporal weighting to reduce motion artifacts. This paper describes a phase based mA modulation that goes beyond axial and ECG modulation; it uses knowledge of the temporal view weighting applied within the reconstruction algorithm to improve dose efficiency in cardiac CT scanning. Using physical phantoms and synthetic noise emulation, we measure how knowledge of sinogram temporal weighting and the prescribed cardiac phase can be used to improve dose efficiency. First, we validated that a synthetic CT noise emulation method produced realistic image noise. Next, we used the CT noise emulation method to simulate mA modulation on scans of a physical anthropomorphic phantom where a motion profile corresponding to a heart rate of 60 beats per minute was used. The CT noise emulation method matched noise to lower dose scans across the image within 1.5% relative error. Using this noise emulation method to simulate modulating the mA while keeping the total dose constant, the image variance was reduced by an average of 11.9% on a scan with 50 msec padding, demonstrating improved dose efficiency. Radiation dose reduction in cardiac CT can be achieved while maintaining the same level of image noise through phase based dose modulation that incorporates knowledge of the cardiac reconstruction algorithm.

Parameterization experiments performed via synthetic mass movements prototypes generated by 3D slope stability simulator

NASA Astrophysics Data System (ADS)

Colangelo, Antonio C.

2010-05-01

The central purpose of this work is to perform a reverse procedure in the mass movement conventional parameterization approach. The idea is to generate a number of synthetic mass movements by means of the "slope stability simulator" (Colangelo, 2007), and compeer their morphological and physical properties with "real" conditions of effective mass movements. This device is an integrated part of "relief unity emulator" (rue), that permits generate synthetic mass movements in a synthetic slope environment. The "rue" was build upon fundamental geomorphological concepts. These devices operate with an integrated set of mechanical, geomorphic and hydrological models. The "slope stability simulator" device (sss) permits to perform a detailed slope stability analysis in a theoretical three dimensional space, by means of evaluation the spatial behavior of critical depths, gradients and saturation levels in the "potential rupture surfaces" inferred along a set of slope profiles, that compounds a synthetic slope unity. It's a meta-stable 4-dimensional object generated by means of "rue", that represents a sequence evolution of a generator profile applied here, was adapted the infinite slope model for slope. Any slope profiles were sliced by means of finite element solution like in Bishop method. For the synthetic slope systems generated, we assume that the potential rupture surface occurs at soil-regolith or soil-rock boundary in slope material. Sixteen variables were included in the "rue-sss" device that operates in an integrated manner. For each cell, the factor of safety was calculated considering the value of shear strength (cohesion and friction) of material, soil-regolith boundary depth, soil moisture level content, potential rupture surface gradient, slope surface gradient, top of subsurface flow gradient, apparent soil bulk density and vegetation surcharge. The slope soil was considered as cohesive material. The 16 variables incorporated in the models were analyzed for each cell in synthetic slope systems performed by relief unity emulator. The central methodological strategy is to locate the potential rupture surfaces (prs), main material discontinuities, like soil-regolith or regolith-rock transitions. Inner these "prs", we would to outline the effective potential rupture surfaces (eprs). This surface is a sub-set of the "prs" that presents safety factor less than unity (f<1), the sub-region in the "prs" equal or deeper than critical depths. When the effective potential rupture surface acquires significant extension with respect the thickness of critical depth and retaining walls, the "slope stability simulator" generates a synthetic mass movement. The overlay material will slide until that a new equilibrium be attained at residual shear strength. These devices generate graphic 3D cinematic sequences of experiments in synthetic slope systems and numerical results about physical and morphological data about scars and deposits. Thus, we have a detailed geotechnical, morphological, topographic and morphometric description of these mass movements prototypes, for deal with effective mass movements found in the real environments.

Enhancing the Critical Role of Malaysian Institute of Higher Education from Ivy League American Universities Research Culture Experiences

ERIC Educational Resources Information Center

Jusoff, Hj. Kamaruzaman; Samah, Hjh. Siti Akmar Abu; Abdullah, Zaini

2009-01-01

Emulation by example is an old adage that has been a pragmatic initiative in great endeavors. To create a dynamic research culture too requires revisiting eminent personality and renowned organization by which one can copy in order to establish credibility. This paper explores the practicality of the emulation activities that help to establish…

The Corporation of Learning: Nonprofit Higher Education Takes Lessons from Business. Research & Occasional Paper Series. CSHE.5.03

ERIC Educational Resources Information Center

Kirp, David L.

2003-01-01

This essay examines the ways in which nonprofit universities increasingly emulate businesses, focusing on two of the most direct forms of emulation: the creation of internal university markets at the University of Southern California through adoption of variants of resource center management (RCM) and the privatization of public higher education…

Using Student Group Work in Higher Education to Emulate Professional Communities of Practice

ERIC Educational Resources Information Center

Fearon, Colm; McLaughlin, Heather; Eng, Tan Yoke

2012-01-01

Purpose: The purpose of this paper is to discuss the value of social learning from group work that emulates a professional community of practice. Design/methodology/approach: A thought piece that first, examines the role of group-work projects as part of social learning, then outlines key arguments for social learning based upon applying a…

Application of a statistical emulator to fire emission modeling

Treesearch

Marwan Katurji; Jovanka Nikolic; Shiyuan Zhong; Scott Pratt; Lejiang Yu; Warren E. Heilman

2015-01-01

We have demonstrated the use of an advanced Gaussian-Process (GP) emulator to estimate wildland fire emissions over a wide range of fuel and atmospheric conditions. The Fire Emission Production Simulator, or FEPS, is used to produce an initial set of emissions data that correspond to some selected values in the domain of the input fuel and atmospheric parameters for...

The Center for Advanced Systems and Engineering (CASE)

DTIC Science & Technology

2012-01-01

targets from multiple sensors. Qinru Qiu, State University of New York at Binghamton – A Neuromorphic Approach for Intelligent Text Recognition...Rogers, SUNYIT, Basic Research, Development and Emulation of Derived Models of Neuromorphic Brain Processes to Investigate the Computational Architecture...Issues They Present Work pertaining to the basic research, development and emulation of derived models of Neuromorphic brain processes to

Extending the Coyote emulator to dark energy models with standard w {sub 0}- w {sub a} parametrization of the equation of state

DOE Office of Scientific and Technical Information (OSTI.GOV)

Casarini, L.; Bonometto, S.A.; Tessarotto, E.

2016-08-01

We discuss an extension of the Coyote emulator to predict non-linear matter power spectra of dark energy (DE) models with a scale factor dependent equation of state of the form w = w {sub 0}+(1- a ) w {sub a} . The extension is based on the mapping rule between non-linear spectra of DE models with constant equation of state and those with time varying one originally introduced in ref. [40]. Using a series of N-body simulations we show that the spectral equivalence is accurate to sub-percent level across the same range of modes and redshift covered by the Coyotemore » suite. Thus, the extended emulator provides a very efficient and accurate tool to predict non-linear power spectra for DE models with w {sub 0}- w {sub a} parametrization. According to the same criteria we have developed a numerical code that we have implemented in a dedicated module for the CAMB code, that can be used in combination with the Coyote Emulator in likelihood analyses of non-linear matter power spectrum measurements. All codes can be found at https://github.com/luciano-casarini/pkequal.« less

An orbital emulator for pursuit-evasion game theoretic sensor management

NASA Astrophysics Data System (ADS)

Shen, Dan; Wang, Tao; Wang, Gang; Jia, Bin; Wang, Zhonghai; Chen, Genshe; Blasch, Erik; Pham, Khanh

2017-05-01

This paper develops and evaluates an orbital emulator (OE) for space situational awareness (SSA). The OE can produce 3D satellite movements using capabilities generated from omni-wheeled robot and robotic arm motion methods. The 3D motion of a satellite is partitioned into the movements in the equatorial plane and the up-down motions in the vertical plane. The 3D actions are emulated by omni-wheeled robot models while the up-down motions are performed by a stepped-motor-controlled-ball along a rod (robotic arm), which is attached to the robot. For multiple satellites, a fast map-merging algorithm is integrated into the robot operating system (ROS) and simultaneous localization and mapping (SLAM) routines to locate the multiple robots in the scene. The OE is used to demonstrate a pursuit-evasion (PE) game theoretic sensor management algorithm, which models conflicts between a space-based-visible (SBV) satellite (as pursuer) and a geosynchronous (GEO) satellite (as evader). The cost function of the PE game is based on the informational entropy of the SBV-tracking-GEO scenario. GEO can maneuver using a continuous and low thruster. The hard-in-loop space emulator visually illustrates the SSA problem solution based PE game.

Appendices to the model description document for a computer program for the emulation/simulation of a space station environmental control and life support system

NASA Technical Reports Server (NTRS)

Yanosy, James L.

1988-01-01

A Model Description Document for the Emulation Simulation Computer Model was already published. The model consisted of a detailed model (emulation) of a SAWD CO2 removal subsystem which operated with much less detailed (simulation) models of a cabin, crew, and condensing and sensible heat exchangers. The purpose was to explore the utility of such an emulation simulation combination in the design, development, and test of a piece of ARS hardware, SAWD. Extensions to this original effort are presented. The first extension is an update of the model to reflect changes in the SAWD control logic which resulted from test. Also, slight changes were also made to the SAWD model to permit restarting and to improve the iteration technique. The second extension is the development of simulation models for more pieces of air and water processing equipment. Models are presented for: EDC, Molecular Sieve, Bosch, Sabatier, a new condensing heat exchanger, SPE, SFWES, Catalytic Oxidizer, and multifiltration. The third extension is to create two system simulations using these models. The first system presented consists of one air and one water processing system. The second consists of a potential air revitalization system.

Appendices to the user's manual for a computer program for the emulation/simulation of a space station environmental control and life support system

NASA Technical Reports Server (NTRS)

Yanosy, James L.

1988-01-01

A user's Manual for the Emulation Simulation Computer Model was published previously. The model consisted of a detailed model (emulation) of a SAWD CO2 removal subsystem which operated with much less detailed (simulation) models of a cabin, crew, and condensing and sensible heat exchangers. The purpose was to explore the utility of such an emulation/simulation combination in the design, development, and test of a piece of ARS hardware - SAWD. Extensions to this original effort are presented. The first extension is an update of the model to reflect changes in the SAWD control logic which resulted from the test. In addition, slight changes were also made to the SAWD model to permit restarting and to improve the iteration technique. The second extension is the development of simulation models for more pieces of air and water processing equipment. Models are presented for: EDC, Molecular Sieve, Bosch, Sabatier, a new condensing heat exchanger, SPE, SFWES, Catalytic Oxidizer, and multifiltration. The third extension is to create two system simulations using these models. The first system presented consists of one air and one water processing system, the second a potential Space Station air revitalization system.

The Mira-Titan Universe. II. Matter Power Spectrum Emulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lawrence, Earl; Heitmann, Katrin; Kwan, Juliana

We introduce a new cosmic emulator for the matter power spectrum covering eight cosmological parameters. Targeted at optical surveys, the emulator provides accurate predictions out to a wavenumber k similar to 5 Mpc(-1) and redshift z <= 2. In addition to covering the standard set of Lambda CDM parameters, massive neutrinos and a dynamical dark energy of state are included. The emulator is built on a sample set of 36 cosmological models, carefully chosen to provide accurate predictions over the wide and large parameter space. For each model, we have performed a high-resolution simulation, augmented with 16 medium-resolution simulations andmore » TimeRG perturbation theory results to provide accurate coverage over a wide k-range; the data set generated as part of this project is more than 1.2Pbytes. With the current set of simulated models, we achieve an accuracy of approximately 4%. Because the sampling approach used here has established convergence and error-control properties, follow-up results with more than a hundred cosmological models will soon achieve similar to 1% accuracy. We compare our approach with other prediction schemes that are based on halo model ideas and remapping approaches.« less

Recent progress in tungsten oxides based memristors and their neuromorphological applications

NASA Astrophysics Data System (ADS)

Qu, Bo; Younis, Adnan; Chu, Dewei

2016-09-01

The advance in conventional silicon based semiconductor industry is now becoming indeterminacy as it still along the road of Moore's Law and concomitant problems associated with it are the emergence of a number of practical issues such as short channel effect. In terms of memory applications, it is generally believed that transistors based memory devices will approach to their scaling limits up to 2018. Therefore, one of the most prominent challenges today in semiconductor industry is the need of a new memory technology which is able to combine the best characterises of current devices. The resistive switching memories which are regarded as "memristors" thus gain great attentions thanks to their specific nonlinear electrical properties. More importantly, their behaviour resembles with the transmission characteristic of synapse in biology. Therefore, the research of synapses biomimetic devices based on memristor will certainly bring a great research prospect in studying synapse emulation as well as building artificial neural networks. Tungsten oxides (WO x ) exhibits many essential characteristics as a great candidate for memristive devices including: accredited endurance (over 105 cycles), stoichiometric flexibility, complimentary metal-oxide-semiconductor (CMOS) process compatibility and configurable properties including non-volatile rectification, memorization and learning functions. Herein, recent progress on Tungsten oxide based materials and its associating memory devices had been reviewed. The possible implementation of this material as a bio-inspired artificial synapse is also highlighted. The penultimate section summaries the current research progress for tungsten oxide based biological synapses and end up with several proposals that have been suggested for possible future developments.

Adaptive oxide electronics: A review

NASA Astrophysics Data System (ADS)

Ha, Sieu D.; Ramanathan, Shriram

2011-10-01

Novel information processing techniques are being actively explored to overcome fundamental limitations associated with CMOS scaling. A new paradigm of adaptive electronic devices is emerging that may reshape the frontiers of electronics and enable new modalities. Creating systems that can learn and adapt to various inputs has generally been a complex algorithm problem in information science, albeit with wide-ranging and powerful applications from medical diagnosis to control systems. Recent work in oxide electronics suggests that it may be plausible to implement such systems at the device level, thereby drastically increasing computational density and power efficiency and expanding the potential for electronics beyond Boolean computation. Intriguing possibilities of adaptive electronics include fabrication of devices that mimic human brain functionality: the strengthening and weakening of synapses emulated by electrically, magnetically, thermally, or optically tunable properties of materials.In this review, we detail materials and device physics studies on functional metal oxides that may be utilized for adaptive electronics. It has been shown that properties, such as resistivity, polarization, and magnetization, of many oxides can be modified electrically in a non-volatile manner, suggesting that these materials respond to electrical stimulus similarly as a neural synapse. We discuss what device characteristics will likely be relevant for integration into adaptive platforms and then survey a variety of oxides with respect to these properties, such as, but not limited to, TaOx, SrTiO3, and Bi4-xLaxTi3O12. The physical mechanisms in each case are detailed and analyzed within the framework of adaptive electronics. We then review theoretically formulated and current experimentally realized adaptive devices with functional oxides, such as self-programmable logic and neuromorphic circuits. Finally, we speculate on what advances in materials physics and engineering may be needed to realize the full potential of adaptive oxide electronics.

Piecewise linear emulator of the nonlinear Schrödinger equation and the resulting analytic solutions for Bose-Einstein condensates.

PubMed

Theodorakis, Stavros

2003-06-01

We emulate the cubic term Psi(3) in the nonlinear Schrödinger equation by a piecewise linear term, thus reducing the problem to a set of uncoupled linear inhomogeneous differential equations. The resulting analytic expressions constitute an excellent approximation to the exact solutions, as is explicitly shown in the case of the kink, the vortex, and a delta function trap. Such a piecewise linear emulation can be used for any differential equation where the only nonlinearity is a Psi(3) one. In particular, it can be used for the nonlinear Schrödinger equation in the presence of harmonic traps, giving analytic Bose-Einstein condensate solutions that reproduce very accurately the numerically calculated ones in one, two, and three dimensions.

Neural networks for self-learning control systems

NASA Technical Reports Server (NTRS)

Nguyen, Derrick H.; Widrow, Bernard

1990-01-01

It is shown how a neural network can learn of its own accord to control a nonlinear dynamic system. An emulator, a multilayered neural network, learns to identify the system's dynamic characteristics. The controller, another multilayered neural network, next learns to control the emulator. The self-trained controller is then used to control the actual dynamic system. The learning process continues as the emulator and controller improve and track the physical process. An example is given to illustrate these ideas. The 'truck backer-upper,' a neural network controller that steers a trailer truck while the truck is backing up to a loading dock, is demonstrated. The controller is able to guide the truck to the dock from almost any initial position. The technique explored should be applicable to a wide variety of nonlinear control problems.

Short-Term Synaptic Plasticity Regulation in Solution-Gated Indium-Gallium-Zinc-Oxide Electric-Double-Layer Transistors.

PubMed

Wan, Chang Jin; Liu, Yang Hui; Zhu, Li Qiang; Feng, Ping; Shi, Yi; Wan, Qing

2016-04-20

In the biological nervous system, synaptic plasticity regulation is based on the modulation of ionic fluxes, and such regulation was regarded as the fundamental mechanism underlying memory and learning. Inspired by such biological strategies, indium-gallium-zinc-oxide (IGZO) electric-double-layer (EDL) transistors gated by aqueous solutions were proposed for synaptic behavior emulations. Short-term synaptic plasticity, such as paired-pulse facilitation, high-pass filtering, and orientation tuning, was experimentally emulated in these EDL transistors. Most importantly, we found that such short-term synaptic plasticity can be effectively regulated by alcohol (ethyl alcohol) and salt (potassium chloride) additives. Our results suggest that solution gated oxide-based EDL transistors could act as the platforms for short-term synaptic plasticity emulation.

An emulator for minimizing finite element analysis implementation resources

NASA Technical Reports Server (NTRS)

Melosh, R. J.; Utku, S.; Salama, M.; Islam, M.

1982-01-01

A finite element analysis emulator providing a basis for efficiently establishing an optimum computer implementation strategy when many calculations are involved is described. The SCOPE emulator determines computer resources required as a function of the structural model, structural load-deflection equation characteristics, the storage allocation plan, and computer hardware capabilities. Thereby, it provides data for trading analysis implementation options to arrive at a best strategy. The models contained in SCOPE lead to micro-operation computer counts of each finite element operation as well as overall computer resource cost estimates. Application of SCOPE to the Memphis-Arkansas bridge analysis provides measures of the accuracy of resource assessments. Data indicate that predictions are within 17.3 percent for calculation times and within 3.2 percent for peripheral storage resources for the ELAS code.

Tailor-made purified human platelet lysate concentrated in neurotrophins for treatment of Parkinson's disease.

PubMed

Chou, Ming-Li; Wu, Joe-Wei; Gouel, Flore; Jonneaux, Aurélie; Timmerman, Kelly; Renn, Ting-Yi; Laloux, Charlotte; Chang, Hung-Ming; Lin, Liang-Tzung; Devedjian, Jean-Christophe; Devos, David; Burnouf, Thierry

2017-10-01

Human platelet lysates (PLs), which contain multiple neurotrophins, have been proposed for treating neurodegenerative disorders, including Parkinson's disease (PD). However, current PLs suspended in plasma have high protein content and contain fibrinogen/fibrin and, following activation, also proteolytic and thrombogenic enzymes. Upon brain administration, such PLs may saturate the cerebrospinal fluid and exert neurotoxicity. We assessed whether purified PLs, concentrated in neurotrophins, protected dopaminergic neurons in PD models. Platelet concentrates were collected by apheresis and centrifuged to eliminate plasma and recover the platelets. Platelets were lysed by freeze-thaw cycles, and the 10-fold concentrated platelet pellet lysates (PPLs) were heat-treated (at 56 °C for 30 min). The heat-treated PPLs were low in total proteins, depleted in both plasma and platelet fibrinogen, and devoid of thrombogenic and proteolytic activities. They exerted very high neuroprotective activity when non-oncogenic, Lund human mesencephalic (LUHMES) cells that had differentiated into dopaminergic neurons were exposed to the MPP + neurotoxin. Heat treatment improved the neuroprotection and inactivated the neurotoxic blood-borne hepatitis C virus. PPL did not induce inflammation in BV2 microglial cells and inhibited COX-2 expression upon lipopolysaccharide exposure. Intranasal administration in mice revealed (a) diffusion of neurotrophins in the striatum and cortex, and (b) MPTP intoxication neuroprotection in the substantia nigra and striatum and the absence of neuroinflammation. These dedicated heat-treated PPLs can be a safe and valuable candidate for a therapeutic strategy for PD. Copyright © 2017 Elsevier Ltd. All rights reserved.

AAV liver expression of FIX-Padua prevents and eradicates FIX inhibitor without increasing thrombogenicity in hemophilia B dogs and mice.

PubMed

Crudele, Julie M; Finn, Jonathan D; Siner, Joshua I; Martin, Nicholas B; Niemeyer, Glenn P; Zhou, Shangzhen; Mingozzi, Federico; Lothrop, Clinton D; Arruda, Valder R

2015-03-05

Emerging successful clinical data on gene therapy using adeno-associated viral (AAV) vector for hemophilia B (HB) showed that the risk of cellular immune response to vector capsid is clearly dose dependent. To decrease the vector dose, we explored AAV-8 (1-3 × 10(12) vg/kg) encoding a hyperfunctional factor IX (FIX-Padua, arginine 338 to leucine) in FIX inhibitor-prone HB dogs. Two naïve HB dogs showed sustained expression of FIX-Padua with an 8- to 12-fold increased specific activity reaching 25% to 40% activity without antibody formation to FIX. A third dog with preexisting FIX inhibitors exhibited a transient anamnestic response (5 Bethesda units) at 2 weeks after vector delivery following by spontaneous eradication of the antibody to FIX by day 70. In this dog, sustained FIX expression reached ∼200% and 30% of activity and antigen levels, respectively. Immune tolerance was confirmed in all dogs after challenges with plasma-derived FIX concentrate. Shortening of the clotting times and lack of bleeding episodes support the phenotypic correction of the severe phenotype, with no clinical or laboratory evidence of risk of thrombosis. Provocative studies in mice showed that FIX-Padua exhibits similar immunogenicity and thrombogenicity compared with FIX wild type. Collectively, these data support the potential translation of gene-based strategies using FIX-Padua for HB. © 2015 by The American Society of Hematology.

Elevated plasma factor VIII enhances venous thrombus formation in rabbits: contribution of factor XI, von Willebrand factor and tissue factor.

PubMed

Sugita, Chihiro; Yamashita, Atsushi; Matsuura, Yunosuke; Iwakiri, Takashi; Okuyama, Nozomi; Matsuda, Shuntaro; Matsumoto, Tomoko; Inoue, Osamu; Harada, Aya; Kitazawa, Takehisa; Hattori, Kunihiro; Shima, Midori; Asada, Yujiro

2013-07-01

Elevated plasma levels of factor VIII (FVIII) are associated with increased risk of deep venous thrombosis. The aim of this study is to elucidate how elevated FVIII levels affect venous thrombus formation and propagation in vivo. We examined rabbit plasma FVIII activity, plasma thrombin generation, whole blood coagulation, platelet aggregation and venous wall thrombogenicity before and one hour after an intravenous infusion of recombinant human FVIII (rFVIII). Venous thrombus induced by the endothelial denudation of rabbit jugular veins was histologically assessed. Thrombus propagation was evaluated as indocyanine green fluorescence intensity. Argatroban, a thrombin inhibitor, and neutralised antibodies for tissue factor (TF), factor XI (FXI), and von Willebrand factor (VWF) were infused before or after thrombus induction to investigate their effects on venous thrombus formation or propagation. Recombinant FVIII (100 IU/kg) increased rabbit plasma FVIII activity two-fold and significantly enhanced whole blood coagulation and total plasma thrombin generation, but did not affect initial thrombin generation time, platelet aggregation and venous wall thrombogenicity. The rFVIII infusion also increased the size of venous thrombus 1 hour after thrombus induction. Argatroban and the antibodies for TF, FXI or VWF inhibited such enhanced thrombus formation and all except TF suppressed thrombus propagation. In conclusion, elevated plasma FVIII levels enhance venous thrombus formation and propagation. Excess thrombin generation by FXI and VWF-mediated FVIII recruitment appear to contribute to the growth of FVIII-driven venous thrombus.

Cardioembolic Stroke

PubMed Central

Kamel, Hooman; Healey, Jeff S.

2017-01-01

Cardiac embolism accounts for an increasing proportion of ischemic strokes, and might multiply several-fold over the next decades. However, research points to several potential strategies to stem this expected rise in cardioembolic stroke. First, although one-third of strokes are of unclear cause, it is increasingly accepted that many of these cryptogenic strokes arise from a distant embolism rather than in-situ cerebrovascular disease, leading to the recent formulation of “embolic stroke of undetermined source” (ESUS) as a distinct target for investigation. Second, recent clinical trials have indicated that ESUS may often stem from subclinical atrial fibrillation (AF) which can be diagnosed with prolonged heart-rhythm monitoring. Third, emerging evidence indicates that a thrombogenic atrial substrate can lead to atrial thromboembolism even in the absence of AF. Such an atrial cardiopathy may explain many cases of ESUS, and oral anticoagulant drugs may prove to reduce stroke risk from atrial cardiopathy given its parallels to AF. Non-vitamin K antagonist oral anticoagulant (NOAC) drugs have recently expanded therapeutic options for preventing cardioembolic stroke and are currently being tested for stroke prevention in patients with ESUS, including specifically those with atrial cardiopathy. Fourth, increasing appreciation of thrombogenic atrial substrate and the common co-existence of cardiac and extra-cardiac stroke risk factors suggests benefits from global vascular risk factor management in addition to anticoagulation. Finally, improved imaging of ventricular thrombus plus the availability of NOAC drugs may lead to better prevention of stroke from acute myocardial infarction and heart failure. PMID:28154101

Platelets derived from the bone marrow of diabetic animals show dysregulated endoplasmic reticulum stress proteins that contribute to increased thrombosis.

PubMed

Hernández Vera, Rodrigo; Vilahur, Gemma; Ferrer-Lorente, Raquel; Peña, Esther; Badimon, Lina

2012-09-01

Patients with diabetes mellitus have an increased risk of suffering atherothrombotic syndromes and are prone to clustering cardiovascular risk factors. However, despite their dysregulated glucose metabolism, intensive glycemic control has proven insufficient to reduce thrombotic complications. Therefore, we aimed to elucidate the determinants of thrombosis in a model of type 2 diabetes mellitus with cardiovascular risk factors clustering. Intravital microscopy was used to analyze thrombosis in vivo in Zucker diabetic fatty rats (ZD) and lean normoglycemic controls. Bone marrow (BM) transplants were performed to test the contribution of each compartment (blood or vessel wall) to thrombogenicity. ZD showed significantly increased thrombosis compared with lean normoglycemic controls. BM transplants demonstrated the key contribution of the hematopoietic compartment to increased thrombogenicity. Indeed, lean normoglycemic controls transplanted with ZD-BM showed increased thrombosis with normal glucose levels, whereas ZD transplanted with lean normoglycemic controls-BM showed reduced thrombosis despite presenting hyperglycemia. Significant alterations in megakaryopoiesis and platelet-endoplasmic reticulum stress proteins, protein disulfide isomerase and 78-kDa glucose-regulated protein, were detected in ZD, and increased tissue factor procoagulant activity was detected in plasma and whole blood of ZD. Our results indicate that diabetes mellitus with cardiovascular risk factor clustering favors BM production of hyperreactive platelets with altered protein disulfide isomerase and 78-kDa glucose-regulated protein expression that can contribute to increase thrombotic risk independently of blood glucose levels.

A Laboratory for Characterizing the Efficacy of Moving Target Defense

DTIC Science & Technology

2016-10-25

of William and Mary are developing a scalable, dynamic, adaptive security system that combines virtualization , emulation, and mutable network...goal with the resource constraints of a small number of servers, and making virtual nodes “real enough” from the view of attackers. Unfortunately, with...we at College of William and Mary are developing a scalable, dynamic, adaptive security system that combines virtualization , emulation, and mutable

Guidance, Navigation and Control Digital Emulation Technology Laboratory. Volume 1. Part 1. Task 1: Digital Emulation Technology Laboratory

DTIC Science & Technology

1991-09-27

complex floating-point functions in a fraction of the time used by the best supercomputers on the market today. These co-processing boards "piggy-back...by the VNIX-based DECLARE program. Ve’ ctLptieu du te, tedi the new verion with main programs that noi, include onlN the variablc required wkith each

Dynamic Emulation Modelling (DEMo) of large physically-based environmental models

NASA Astrophysics Data System (ADS)

Galelli, S.; Castelletti, A.

2012-12-01

In environmental modelling large, spatially-distributed, physically-based models are widely adopted to describe the dynamics of physical, social and economic processes. Such an accurate process characterization comes, however, to a price: the computational requirements of these models are considerably high and prevent their use in any problem requiring hundreds or thousands of model runs to be satisfactory solved. Typical examples include optimal planning and management, data assimilation, inverse modelling and sensitivity analysis. An effective approach to overcome this limitation is to perform a top-down reduction of the physically-based model by identifying a simplified, computationally efficient emulator, constructed from and then used in place of the original model in highly resource-demanding tasks. The underlying idea is that not all the process details in the original model are equally important and relevant to the dynamics of the outputs of interest for the type of problem considered. Emulation modelling has been successfully applied in many environmental applications, however most of the literature considers non-dynamic emulators (e.g. metamodels, response surfaces and surrogate models), where the original dynamical model is reduced to a static map between input and the output of interest. In this study we focus on Dynamic Emulation Modelling (DEMo), a methodological approach that preserves the dynamic nature of the original physically-based model, with consequent advantages in a wide variety of problem areas. In particular, we propose a new data-driven DEMo approach that combines the many advantages of data-driven modelling in representing complex, non-linear relationships, but preserves the state-space representation typical of process-based models, which is both particularly effective in some applications (e.g. optimal management and data assimilation) and facilitates the ex-post physical interpretation of the emulator structure, thus enhancing the credibility of the model to stakeholders and decision-makers. Numerical results from the application of the approach to the reduction of 3D coupled hydrodynamic-ecological models in several real world case studies, including Marina Reservoir (Singapore) and Googong Reservoir (Australia), are illustrated.

Analysis of Public Datasets for Wearable Fall Detection Systems.

PubMed

Casilari, Eduardo; Santoyo-Ramón, José-Antonio; Cano-García, José-Manuel

2017-06-27

Due to the boom of wireless handheld devices such as smartwatches and smartphones, wearable Fall Detection Systems (FDSs) have become a major focus of attention among the research community during the last years. The effectiveness of a wearable FDS must be contrasted against a wide variety of measurements obtained from inertial sensors during the occurrence of falls and Activities of Daily Living (ADLs). In this regard, the access to public databases constitutes the basis for an open and systematic assessment of fall detection techniques. This paper reviews and appraises twelve existing available data repositories containing measurements of ADLs and emulated falls envisaged for the evaluation of fall detection algorithms in wearable FDSs. The analysis of the found datasets is performed in a comprehensive way, taking into account the multiple factors involved in the definition of the testbeds deployed for the generation of the mobility samples. The study of the traces brings to light the lack of a common experimental benchmarking procedure and, consequently, the large heterogeneity of the datasets from a number of perspectives (length and number of samples, typology of the emulated falls and ADLs, characteristics of the test subjects, features and positions of the sensors, etc.). Concerning this, the statistical analysis of the samples reveals the impact of the sensor range on the reliability of the traces. In addition, the study evidences the importance of the selection of the ADLs and the need of categorizing the ADLs depending on the intensity of the movements in order to evaluate the capability of a certain detection algorithm to discriminate falls from ADLs.

Analysis of Public Datasets for Wearable Fall Detection Systems

PubMed Central

Santoyo-Ramón, José-Antonio; Cano-García, José-Manuel

2017-01-01

Due to the boom of wireless handheld devices such as smartwatches and smartphones, wearable Fall Detection Systems (FDSs) have become a major focus of attention among the research community during the last years. The effectiveness of a wearable FDS must be contrasted against a wide variety of measurements obtained from inertial sensors during the occurrence of falls and Activities of Daily Living (ADLs). In this regard, the access to public databases constitutes the basis for an open and systematic assessment of fall detection techniques. This paper reviews and appraises twelve existing available data repositories containing measurements of ADLs and emulated falls envisaged for the evaluation of fall detection algorithms in wearable FDSs. The analysis of the found datasets is performed in a comprehensive way, taking into account the multiple factors involved in the definition of the testbeds deployed for the generation of the mobility samples. The study of the traces brings to light the lack of a common experimental benchmarking procedure and, consequently, the large heterogeneity of the datasets from a number of perspectives (length and number of samples, typology of the emulated falls and ADLs, characteristics of the test subjects, features and positions of the sensors, etc.). Concerning this, the statistical analysis of the samples reveals the impact of the sensor range on the reliability of the traces. In addition, the study evidences the importance of the selection of the ADLs and the need of categorizing the ADLs depending on the intensity of the movements in order to evaluate the capability of a certain detection algorithm to discriminate falls from ADLs. PMID:28653991

Bismuth Infusion of ABS Enables Additive Manufacturing of Complex Radiological Phantoms and Shielding Equipment.

PubMed

Ceh, Justin; Youd, Tom; Mastrovich, Zach; Peterson, Cody; Khan, Sarah; Sasser, Todd A; Sander, Ian M; Doney, Justin; Turner, Clark; Leevy, W Matthew

2017-02-24

Radiopacity is a critical property of materials that are used for a range of radiological applications, including the development of phantom devices that emulate the radiodensity of native tissues and the production of protective equipment for personnel handling radioactive materials. Three-dimensional (3D) printing is a fabrication platform that is well suited to creating complex anatomical replicas or custom labware to accomplish these radiological purposes. We created and tested multiple ABS (Acrylonitrile butadiene styrene) filaments infused with varied concentrations of bismuth (1.2-2.7 g/cm³), a radiopaque metal that is compatible with plastic infusion, to address the poor gamma radiation attenuation of many mainstream 3D printing materials. X-ray computed tomography (CT) experiments of these filaments indicated that a density of 1.2 g/cm³ of bismuth-infused ABS emulates bone radiopacity during X-ray CT imaging on preclinical and clinical scanners. ABS-bismuth filaments along with ABS were 3D printed to create an embedded human nasocranial anatomical phantom that mimicked radiological properties of native bone and soft tissue. Increasing the bismuth content in the filaments to 2.7 g/cm³ created a stable material that could attenuate 50% of 99m Technetium gamma emission when printed with a 2.0 mm wall thickness. A shielded test tube rack was printed to attenuate source radiation as a protective measure for lab personnel. We demonstrated the utility of novel filaments to serve multiple radiological purposes, including the creation of anthropomorphic phantoms and safety labware, by tuning the level of radiation attenuation through material customization.

The third level trigger and output event unit of the UA1 data-acquisition system

NASA Astrophysics Data System (ADS)

Cittolin, S.; Demoulin, M.; Fucci, A.; Haynes, W.; Martin, B.; Porte, J. P.; Sphicas, P.

1989-12-01

The upgraded UA1 experiment utilizes twelve 3081/E emulators for its third-level trigger system. The system is interfaced to VME, and is controlled by 68000 microprocessor VME boards on the input and output. The output controller communicates with an IBM 9375 mainframe via the CERN-IBM developed VICI interface. The events selected by the emulators are output on IBM-3480 cassettes. The user interface to this system is based on a series of Macintosh personal computer connected to the VME bus. These Macs are also used for developing software for the emulators and for monitoring the entire system. The same configuration has also been used for offline event reconstruction. A description of the system, together with details of both the online and offline modes of operation and an eveluation of its performance are presented.

A novel low-profile thin-film nitinol/silk endograft for treating small vascular diseases.

PubMed

Shayan, Mahdis; Yang, Sungyeun; Ryu, WonHyoung; Chun, Youngjae

2017-04-01

Since the introduction of various endovascular graft materials such as expanded polytetrafluoroethylene (e-PTFE) and Dacron ® polyester, they have been rapidly applied in endovascular devices for treating a variety of clinical situations. While present endovascular grafts have been successful in treating large blood vessels, there are still significant challenges and limitations for small and tortuous vessels to their use. Recently, our group has demonstrated the potential to use thin-film nitinol (TFN) as a novel material to develop endografts used in the treatment of a wide range of small vascular diseases because TFN is ultralow profile (that is, a few micrometers thick), relatively thromboresistant, and superelastic. While TFN has shown superior thromboresistance, its surface endothelialization is not rapid and sufficient. Therefore, our laboratory has been exploring the feasibility of using thin-film silk as a novel coating for facilitating rapid and confluent endothelial cell growth. The purpose of this study is to fabricate a low-profile composite endograft using thin layers of nitinol and silk, and to evaluate both thrombogenicity as well as endothelial cell and smooth muscle cell responses. This study also evaluates the functionality of the composite endograft using an in vitro blood circulation model. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 575-584, 2017. © 2015 Wiley Periodicals, Inc.

Sulfonated chitosan and dopamine based coatings for metallic implants in contact with blood.

PubMed

Campelo, Clayton S; Chevallier, Pascale; Vaz, Juliana M; Vieira, Rodrigo S; Mantovani, Diego

2017-03-01

Thrombosis and calcification constitute the main clinical problems when blood-interacting devices are implanted in the body. Coatings with thin polymer layers represent an acknowledged strategy to modulate interactions between the material surface and the blood environment. To ensure the implant success, at short-term the coating should limit platelets adhesion and delay the clot formation, and at long-term it should delay the calcification process. Sulfonated chitosan, if compared to native chitosan, shows the unique ability to reduce proteins adsorption, decrease thrombogenic properties and limit calcification. In this work, stainless steel surfaces, commonly used for cardiovascular applications, were coated with sulfonated chitosan, by using dopamine and PEG as anchors, and the effect of these grafted surfaces on platelet adhesion, clot formation as well as on calcification were investigated. Surface characterization techniques evidenced that the coating formation was successful, and the sulfonated chitosan grafted sample exhibited a higher roughness and hydrophilicity, if compared to native chitosan one. Moreover, sulfonated surface limited platelet activation and the process of clot formation, thus confirming its high biological performances in blood. Calcium deposits were also lower on the sulfonated chitosan sample compared to the chitosan one, thus showing that calcification was minimal in presence of sulfonate groups. In conclusion, this sulfonated-modified surface has potential to be as blood-interacting material. Copyright © 2016. Published by Elsevier B.V.

Biodegradable, elastomeric coatings with controlled anti-proliferative agent release for magnesium-based cardiovascular stents.

PubMed

Gu, Xinzhu; Mao, Zhongwei; Ye, Sang-Ho; Koo, Youngmi; Yun, Yeoheung; Tiasha, Tarannum R; Shanov, Vesselin; Wagner, William R

2016-08-01

Vascular stent design continues to evolve to further improve the efficacy and minimize the risks associated with these devices. Drug-eluting coatings have been widely adopted and, more recently, biodegradable stents have been the focus of extensive evaluation. In this report, biodegradable elastomeric polyurethanes were synthesized and applied as drug-eluting coatings for a relatively new class of degradable vascular stents based on Mg. The dynamic degradation behavior, hemocompatibility and drug release were investigated for poly(carbonate urethane) urea (PCUU) and poly(ester urethane) urea (PEUU) coated magnesium alloy (AZ31) stents. Poly(lactic-co-glycolic acid) (PLGA) coated and bare stents were employed as control groups. The PCUU coating effectively slowed the Mg alloy corrosion in dynamic degradation testing compared to PEUU-coated, PLGA-coated and bare Mg alloy stents. This was confirmed by electron microscopy, energy-dispersive x-ray spectroscopy and magnesium ion release experiments. PCUU-coating of AZ31 was also associated with significantly reduced platelet adhesion in acute blood contact testing. Rat vascular smooth muscle cell (rSMC) proliferation was successfully inhibited when paclitaxel was released from pre-loaded PCUU coatings. The corrosion retardation, low thrombogenicity, drug loading capacity, and high elasticity make PCUU an attractive option for drug eluting coating on biodegradable metallic cardiovascular stents. Copyright © 2016 Elsevier B.V. All rights reserved.

Plasma functionalization of polycarbonaturethane to improve endothelialization--Effect of shear stress as a critical factor for biocompatibility control.

PubMed

Lukas, Karin; Thomas, Ulrich; Gessner, André; Wehner, Daniel; Schmid, Thomas; Schmid, Christof; Lehle, Karla

2016-04-01

Medical devices made of polycarbonaturethane (PCU) combine excellent mechanical properties and little biological degradation, but restricted hemocompatibility. Modifications of PCU might reduce platelet adhesion and promote stable endothelialization. PCU was modified using gas plasma treatment, binding of hydrogels, and coupling of cell-active molecules (modified heparin, anti-thrombin III (ATIII), argatroban, fibronectin, laminin-nonapeptide, peptides with integrin-binding arginine-glycine-aspartic acid (RGD) motif). Biocompatibility was verified with static and dynamic cell culture techniques. Blinded analysis focused on improvement in endothelial cell (EC) adhesion/proliferation, anti-thrombogenicity, reproducible manufacturing process, and shear stress tolerance of ECs. EC adhesion and antithrombogenicity were achieved with 9/35 modifications. Additionally, 6/9 stimulated EC proliferation and 3/6 modification processes were highly reproducible for endothelialization. The latter modifications comprised immobilization of ATIII (A), polyethyleneglycole-diamine-hydrogel (E) and polyethylenimine-hydrogel connected with modified heparin (IH). Under sheer stress, only the IH modification improved EC adhesion within the graft. However, ECs did not arrange in flow direction and cell anchorage was restricted. Despite large variation in surface modification chemistry and improved EC adhesion under static culture conditions, additional introduction of shear stress foiled promising preliminary data. Therefore, biocompatibility testing required not only static tests but also usage of physiological conditions such as shear stress in the case of vascular grafts. © The Author(s) 2016.

Safety Evaluation of New Hemostatic Agents, Smectite Granules, and Kaolin-Coated Gauze in a Vascular Injury Wound Model in Swine

DTIC Science & Technology

2010-02-01

risk of using WS when compared with kaolin-coated gauze, Combat Gauze (CG); or regular gauze, Kerlix (KX) to treat an external wound with vascular...communication with combat medics implied limited use or avoidance of these agents in the field because of either painful side effects (thermal injury with QC...potential thrombogenicity of WS and CG when they are used to control external bleeding due to major vascular injury. For this purpose, a new wound model was

Changes in the human blood coagulating system during prolonged hypokinesia

NASA Technical Reports Server (NTRS)

Filatova, L. M.; Anashkin, O. D.

1978-01-01

Changes in the coagulating system of the blood were studied in six subjects during prolonged hypokinesia. Thrombogenic properties of the blood rose in all cases on the 8th day. These changes are explained by stress reaction due to unusual conditions for a healthy person. Changes in the blood coagulating system in the group subjected to physical exercise and without it ran a practically parallel course. Apparently physical exercise is insufficient to prevent such changes that appear in the coagulating system of the blood during prolonged hypokinesia.

A Voice-Detecting Sensor and a Scanning Keyboard Emulator to Support Word Writing by Two Boys with Extensive Motor Disabilities

ERIC Educational Resources Information Center

Lancioni, Giulio E.; Singh, Nirbhay N.; O'Reilly, Mark F.; Sigafoos, Jeff; Green, Vanessa; Chiapparino, Claudia; Stasolla, Fabrizio; Oliva, Doretta

2009-01-01

The present study assessed the use of a voice-detecting sensor interfaced with a scanning keyboard emulator to allow two boys with extensive motor disabilities to write. Specifically, the study (a) compared the effects of the voice-detecting sensor with those of a familiar pressure sensor on the boys' writing time, (b) checked which of the sensors…

Distributed Spectral Monitoring For Emitter Localization

DTIC Science & Technology

2018-02-12

localization techniques in a DSA sensor network. The results of the research are presented through simulation of localization algorithms, emulation of a...network on a wireless RF environment emulator, and field tests. The results of the various tests in both the lab and field are obtained and analyzed to... are two main classes of localization techniques, and the technique to use will depend on the information available with the emitter. The first class

A Structured Microprogram Set for the SUMC Computer to Emulate the IBM System/360, Model 50

NASA Technical Reports Server (NTRS)

Gimenez, Cesar R.

1975-01-01

Similarities between regular and structured microprogramming were examined. An explanation of machine branching architecture (particularly in the SUMC computer), required for ease of structured microprogram implementation is presented. Implementation of a structured microprogram set in the SUMC to emulate the IBM System/360 is described and a comparison is made between the structured set with a nonstructured set previously written for the SUMC.

Becoming a high-fidelity - super - imitator: what are the contributions of social and individual learning?

PubMed

Subiaul, Francys; Patterson, Eric M; Schilder, Brian; Renner, Elizabeth; Barr, Rachel

2015-11-01

In contrast to other primates, human children's imitation performance goes from low to high fidelity soon after infancy. Are such changes associated with the development of other forms of learning? We addressed this question by testing 215 children (26-59 months) on two social conditions (imitation, emulation) - involving a demonstration - and two asocial conditions (trial-and-error, recall) - involving individual learning - using two touchscreen tasks. The tasks required responding to either three different pictures in a specific picture order (Cognitive: Airplane→Ball→Cow) or three identical pictures in a specific spatial order (Motor-Spatial: Up→Down→Right). There were age-related improvements across all conditions and imitation, emulation and recall performance were significantly better than trial-and-error learning. Generalized linear models demonstrated that motor-spatial imitation fidelity was associated with age and motor-spatial emulation performance, but cognitive imitation fidelity was only associated with age. While this study provides evidence for multiple imitation mechanisms, the development of one of those mechanisms - motor-spatial imitation - may be bootstrapped by the development of another social learning skill - motor-spatial emulation. Together, these findings provide important clues about the development of imitation, which is arguably a distinctive feature of the human species. © 2014 John Wiley & Sons Ltd.

E-cigarettes: a rapidly growing Internet phenomenon.

PubMed

Yamin, Cyrus K; Bitton, Asaf; Bates, David W

2010-11-02

Electronic cigarettes (e-cigarettes) aerosolize nicotine and produce a vapor that emulates that of cigarettes but purportedly has fewer traditional toxins than secondhand smoke. Although e-cigarettes are widely sold online and by retailers, new research suggests that they may contain unexpected toxins and may provide unreliable nicotine delivery. Many countries have already banned or strictly regulated e-cigarettes. Currently in the United States, e-cigarettes are exempt from regulation as drug-delivery devices. Meanwhile, the presence of e-cigarettes on the Internet, including in Web searches, virtual user communities, and online stores where people sell e-cigarettes on commission, is increasing rapidly. Physicians should be aware of the popularity, questionable efficacy claims, and safety concerns of e-cigarettes so that they may counsel patients against use and advocate for research to inform an evidence-based regulatory approach.

Digital optical computer II

NASA Astrophysics Data System (ADS)

Guilfoyle, Peter S.; Stone, Richard V.

1991-12-01

OptiComp is currently completing a 32-bit, fully programmable digital optical computer (DOC II) that is designed to operate in a UNIX environment running RISC microcode. OptiComp's DOC II architecture is focused toward parallel microcode implementation where data is input in a dual rail format. By exploiting the physical principals inherent to optics (speed and low power consumption), an architectural balance of optical interconnects and software code efficiency can be achieved including high fan-in and fan-out. OptiComp's DOC II program is jointly sponsored by the Office of Naval Research (ONR), the Strategic Defense Initiative Office (SDIO), NASA space station group and Rome Laboratory (USAF). This paper not only describes the motivational basis behind DOC II but also provides an optical overview and architectural summary of the device that allows the emulation of any digital instruction set.

Analog Approach to Constraint Satisfaction Enabled by Spin Orbit Torque Magnetic Tunnel Junctions.

PubMed

Wijesinghe, Parami; Liyanagedera, Chamika; Roy, Kaushik

2018-05-02

Boolean satisfiability (k-SAT) is an NP-complete (k ≥ 3) problem that constitute one of the hardest classes of constraint satisfaction problems. In this work, we provide a proof of concept hardware based analog k-SAT solver, that is built using Magnetic Tunnel Junctions (MTJs). The inherent physics of MTJs, enhanced by device level modifications, is harnessed here to emulate the intricate dynamics of an analog satisfiability (SAT) solver. In the presence of thermal noise, the MTJ based system can successfully solve Boolean satisfiability problems. Most importantly, our results exhibit that, the proposed MTJ based hardware SAT solver is capable of finding a solution to a significant fraction (at least 85%) of hard 3-SAT problems, within a time that has a polynomial relationship with the number of variables(<50).

Virus based Full Colour Pixels using a Microheater

NASA Astrophysics Data System (ADS)

Kim, Won-Geun; Kim, Kyujung; Ha, Sung-Hun; Song, Hyerin; Yu, Hyun-Woo; Kim, Chuntae; Kim, Jong-Man; Oh, Jin-Woo

2015-09-01

Mimicking natural structures has been received considerable attentions, and there have been a few practical advances. Tremendous efforts based on a self-assembly technique have been contributed to the development of the novel photonic structures which are mimicking nature’s inventions. We emulate the photonic structures from an origin of colour generation of mammalian skins and avian skin/feathers using M13 phage. The structures can be generated a full range of RGB colours that can be sensitively switched by temperature and substrate materials. Consequently, we developed an M13 phage-based temperature-dependent actively controllable colour pixels platform on a microheater chip. Given the simplicity of the fabrication process, the low voltage requirements and cycling stability, the virus colour pixels enable us to substitute for conventional colour pixels for the development of various implantable, wearable and flexible devices in future.

Radiation Mitigation and Power Optimization Design Tools for Reconfigurable Hardware in Orbit

NASA Technical Reports Server (NTRS)

French, Matthew; Graham, Paul; Wirthlin, Michael; Wang, Li; Larchev, Gregory

2005-01-01

The Reconfigurable Hardware in Orbit (RHinO)project is focused on creating a set of design tools that facilitate and automate design techniques for reconfigurable computing in space, using SRAM-based field-programmable-gate-array (FPGA) technology. In the second year of the project, design tools that leverage an established FPGA design environment have been created to visualize and analyze an FPGA circuit for radiation weaknesses and power inefficiencies. For radiation, a single event Upset (SEU) emulator, persistence analysis tool, and a half-latch removal tool for Xilinx/Virtex-II devices have been created. Research is underway on a persistence mitigation tool and multiple bit upsets (MBU) studies. For power, synthesis level dynamic power visualization and analysis tools have been completed. Power optimization tools are under development and preliminary test results are positive.

Emulation of complex open quantum systems using superconducting qubits

NASA Astrophysics Data System (ADS)

Mostame, Sarah; Huh, Joonsuk; Kreisbeck, Christoph; Kerman, Andrew J.; Fujita, Takatoshi; Eisfeld, Alexander; Aspuru-Guzik, Alán

2017-02-01

With quantum computers being out of reach for now, quantum simulators are alternative devices for efficient and accurate simulation of problems that are challenging to tackle using conventional computers. Quantum simulators are classified into analog and digital, with the possibility of constructing "hybrid" simulators by combining both techniques. Here we focus on analog quantum simulators of open quantum systems and address the limit that they can beat classical computers. In particular, as an example, we discuss simulation of the chlorosome light-harvesting antenna from green sulfur bacteria with over 250 phonon modes coupled to each electronic state. Furthermore, we propose physical setups that can be used to reproduce the quantum dynamics of a standard and multiple-mode Holstein model. The proposed scheme is based on currently available technology of superconducting circuits consist of flux qubits and quantum oscillators.

Enabling an Integrated Rate-temporal Learning Scheme on Memristor

NASA Astrophysics Data System (ADS)

He, Wei; Huang, Kejie; Ning, Ning; Ramanathan, Kiruthika; Li, Guoqi; Jiang, Yu; Sze, Jiayin; Shi, Luping; Zhao, Rong; Pei, Jing

2014-04-01

Learning scheme is the key to the utilization of spike-based computation and the emulation of neural/synaptic behaviors toward realization of cognition. The biological observations reveal an integrated spike time- and spike rate-dependent plasticity as a function of presynaptic firing frequency. However, this integrated rate-temporal learning scheme has not been realized on any nano devices. In this paper, such scheme is successfully demonstrated on a memristor. Great robustness against the spiking rate fluctuation is achieved by waveform engineering with the aid of good analog properties exhibited by the iron oxide-based memristor. The spike-time-dependence plasticity (STDP) occurs at moderate presynaptic firing frequencies and spike-rate-dependence plasticity (SRDP) dominates other regions. This demonstration provides a novel approach in neural coding implementation, which facilitates the development of bio-inspired computing systems.

Performance Evaluation, Emulation, and Control of Cross-Flow Hydrokinetic Turbines

NASA Astrophysics Data System (ADS)

Cavagnaro, Robert J.

Cross-flow hydrokinetic turbines are a promising option for effectively harvesting energy from fast-flowing streams or currents. This work describes the dynamics of such turbines, analyzes techniques used to scale turbine properties for prototyping, determines and demonstrates the limits of stability for cross-flow rotors, and discusses means and objectives of turbine control. Novel control strategies are under development to utilize low-speed operation (slower than at maximum power point) as a means of shedding power under rated conditions. However, operation in this regime may be unstable. An experiment designed to characterize the stability of a laboratory-scale cross-flow turbine operating near a critically low speed yields evidence that system stall (complete loss of ability to rotate) occurs due, in part, to interactions with turbulent decreases in flow speed. The turbine is capable of maintaining 'stable' operation at critical speed for short duration (typically less than 10 s), as described by exponential decay. The presence of accelerated 'bypass' flow around the rotor and decelerated 'induction' region directly upstream of the rotor, both predicted by linear momentum theory, are observed and quantified with particle image velocimetry (PIV) measurements conducted upstream of the turbine. Additionally, general agreement is seen between PIV inflow measurements and those obtained by an advection-corrected acoustic Doppler velocimeter (ADV) further upstream. Performance of a turbine at small (prototype) geometric scale may be prone to undesirable effects due to operation at low Reynolds number and in the presence of high channel blockage. Therefore, testing at larger scale, in open water is desirable. A cross-flow hydrokinetic turbine with a projected area (product of blade span and rotor diameter) of 0.7 m2 is evaluated in open-water tow trials at three inflow speeds ranging from 1.0 m/s to 2.1 m/s. Measurements of the inflow velocity, the rotor mechanical power, and electrical power output of a complete power take-off (PTO) system are utilized to determine the rotor hydrodynamic efficiency (maximum of 17%) and total system efficiency (maximum of 9%). A lab-based dynamometry method yields individual component and total PTO efficiencies, shown to have high variability and strong influence on total system efficiency. Dynamic efficiencies of PTO components can effect the overall efficiency of a turbine system, a result from field characterization. Thus, the ability to evaluate such components and their potential effects on turbine performance prior to field deployment is desirable. Before attempting control experiments with actual turbines, hardware-in-the-loop testing on controllable motor-generator sets or electromechanical emulation machines (EEMs) are explored to better understand power take-off response. The emulator control dynamic equations are presented, methods for scaling turbine parameters are developed and evaluated, and experimental results are presented from three EEMs programmed to emulate the same cross-flow turbine. Although hardware platforms and control implementations varied, results show that each EEM is successful in emulating the turbine model at different power levels, thus demonstrating the general feasibility of the approach. However, performance of motor control under torque command, current command, or speed command differed; torque methods required accurate characterization of the motors while speed methods utilized encoder feedback and more accurately tracked turbine dynamics. In a demonstration of an EEM for evaluating a hydrokinetic turbine implementation, a controller is used to track the maximum power-point of the turbine in response to turbulence. Utilizing realistic inflow conditions and control laws, the emulator dynamic speed response is shown to agree well at low frequencies with simulation but to deviate at high frequencies. The efficacy of an electromechanical emulator as an accurate representation of a fielded turbine is evaluated. A commercial horizontally-oriented cross-flow turbine is dynamically emulated on hardware to investigate control strategies and grid integration. A representative inflow time-series with a mean of 2 m/s is generated from high-resolution flow measurements of a riverine site and is used to drive emulation. Power output during emulation under similar input and loading conditions yields agreement with field measurements to within 3% at high power, near-optimal levels. Constant tip-speed ratio and constant speed proportional plus integral control schemes are compared to optimal nonlinear control and constant resistance regulation. All controllers yield similar results in terms of overall system efficiency. The emulated turbine is more responsive to turbulent inflow than the field turbine, as the model utilized to drive emulation does not account for a smoothing effect of turbulent fluctuations over the span of the fielded turbine's rotors. The turbine has a lower inertia than the demand of an isolated grid, indicating a secondary source of power with a similar frequency response is necessary if a single turbine cannot meet the entire demand. (Abstract shortened by UMI.).

Autonomic Intelligent Cyber Sensor to Support Industrial Control Network Awareness

DOE PAGES

Vollmer, Todd; Manic, Milos; Linda, Ondrej

2013-06-01

The proliferation of digital devices in a networked industrial ecosystem, along with an exponential growth in complexity and scope, has resulted in elevated security concerns and management complexity issues. This paper describes a novel architecture utilizing concepts of Autonomic computing and a SOAP based IF-MAP external communication layer to create a network security sensor. This approach simplifies integration of legacy software and supports a secure, scalable, self-managed framework. The contribution of this paper is two-fold: 1) A flexible two level communication layer based on Autonomic computing and Service Oriented Architecture is detailed and 2) Three complementary modules that dynamically reconfiguremore » in response to a changing environment are presented. One module utilizes clustering and fuzzy logic to monitor traffic for abnormal behavior. Another module passively monitors network traffic and deploys deceptive virtual network hosts. These components of the sensor system were implemented in C++ and PERL and utilize a common internal D-Bus communication mechanism. A proof of concept prototype was deployed on a mixed-use test network showing the possible real world applicability. In testing, 45 of the 46 network attached devices were recognized and 10 of the 12 emulated devices were created with specific Operating System and port configurations. Additionally the anomaly detection algorithm achieved a 99.9% recognition rate. All output from the modules were correctly distributed using the common communication structure.« less

Flexible Low-Mass Devices and Mechanisms Actuated by Electroactive Polymers

NASA Technical Reports Server (NTRS)

Bar-Cohen, Y; Leary, S.; Shahinpoor, M.; Harrison, J. O.; Smith, J.

1999-01-01

Miniature, lightweight, miser actuators that operate similar to biological muscles can be used to develop robotic devices with unmatched capabilities to impact many technology areas. Electroactive polymers (EAP) offer the potential to producing such actuators and their main attractive feature is their ability to induce relatively large bending or longitudinal strain. Generally, these materials produce a relatively low force and the applications that can be considered at the current state of the art are relatively limited. This reported study is concentrating on the development of effective EAPs and the resultant enabling mechanisms employing their unique characteristics. Several EAP driven mechanisms, which emulate human hand, were developed including a gripper, manipulator arm and surface wiper. The manipulator arm was made of a composite rod with an EAP actuator consisting of a scrolled rope that is activated longitudinally by an electrostatic field. A gripper was made to serve as an end effector and it consisted of multiple bending EAP fingers for grabbing and holding such objects as rocks. An EAP surface wiper was developed to operate like a human finger and to demonstrate the potential to remove dust from optical and IR windows as well as solar cells. These EAP driven devices are taking advantage of the large actuation displacement of these materials but there is need for a significantly greater actuation force capability.

Quantum Emulation of Gravitational Waves.

PubMed

Fernandez-Corbaton, Ivan; Cirio, Mauro; Büse, Alexander; Lamata, Lucas; Solano, Enrique; Molina-Terriza, Gabriel

2015-07-14

Gravitational waves, as predicted by Einstein's general relativity theory, appear as ripples in the fabric of spacetime traveling at the speed of light. We prove that the propagation of small amplitude gravitational waves in a curved spacetime is equivalent to the propagation of a subspace of electromagnetic states. We use this result to propose the use of entangled photons to emulate the evolution of gravitational waves in curved spacetimes by means of experimental electromagnetic setups featuring metamaterials.

A Scalable and Dynamic Testbed for Conducting Penetration-Test Training in a Laboratory Environment

DTIC Science & Technology

2015-03-01

entry point through which to execute a payload to accomplish a higher-level goal: executing arbitrary code, escalating privileges , pivoting...Mobile Ad Hoc Network Emulator (EMANE)26 can emulate the entire network stack (physical to application -layer protocols). 2. Methodology To build a...to host Windows, Linux, MacOS, Android , and other operating systems without much effort. 4 E. A simple and automatic “restore” function: Many

On the diagnostic emulation technique and its use in the AIRLAB

NASA Technical Reports Server (NTRS)

Migneault, Gerard E.

1988-01-01

An aid is presented for understanding and judging the relevance of the diagnostic emulation technique to studies of highly reliable, digital computing systems for aircraft. A short review is presented of the need for and the use of the technique as well as an explanation of its principles of operation and implementation. Details that would be needed for operational control or modification of existing versions of the technique are not described.

Tools and Methods to Create Scenarios for Experimental Research in the Network Science Research Laboratory (NSRL)

DTIC Science & Technology

2015-12-01

research areas in network science. 15. SUBJECT TERMS scenario creation , emulation environment, NSRL 16. SECURITY CLASSIFICATION OF: 17. LIMITATION...mobility aspect of the emulated environment, the development and creation of scenarios play an integral part. By creating scenarios that model certain...during the visualization phase. We examine these 3 phases in detail by describing the creation of a scenario based upon a vignette from the Multi-Level

Statistical Emulation of Climate Model Projections Based on Precomputed GCM Runs*

DOE PAGES

Castruccio, Stefano; McInerney, David J.; Stein, Michael L.; ...

2014-02-24

The authors describe a new approach for emulating the output of a fully coupled climate model under arbitrary forcing scenarios that is based on a small set of precomputed runs from the model. Temperature and precipitation are expressed as simple functions of the past trajectory of atmospheric CO 2 concentrations, and a statistical model is fit using a limited set of training runs. The approach is demonstrated to be a useful and computationally efficient alternative to pattern scaling and captures the nonlinear evolution of spatial patterns of climate anomalies inherent in transient climates. The approach does as well as patternmore » scaling in all circumstances and substantially better in many; it is not computationally demanding; and, once the statistical model is fit, it produces emulated climate output effectively instantaneously. In conclusion, it may therefore find wide application in climate impacts assessments and other policy analyses requiring rapid climate projections.« less

Microwave emulations and tight-binding calculations of transport in polyacetylene

NASA Astrophysics Data System (ADS)

Stegmann, Thomas; Franco-Villafañe, John A.; Ortiz, Yenni P.; Kuhl, Ulrich; Mortessagne, Fabrice; Seligman, Thomas H.

2017-01-01

A novel approach to investigate the electron transport of cis- and trans-polyacetylene chains in the single-electron approximation is presented by using microwave emulation measurements and tight-binding calculations. In the emulation we take into account the different electronic couplings due to the double bonds leading to coupled dimer chains. The relative coupling constants are adjusted by DFT calculations. For sufficiently long chains a transport band gap is observed if the double bonds are present, whereas for identical couplings no band gap opens. The band gap can be observed also in relatively short chains, if additional edge atoms are absent, which cause strong resonance peaks within the band gap. The experimental results are in agreement with our tight-binding calculations using the nonequilibrium Green's function method. The tight-binding calculations show that it is crucial to include third nearest neighbor couplings to obtain the gap in the cis-polyacetylene.

Emulation and design of terahertz reflection-mode confocal scanning microscopy based on virtual pinhole

NASA Astrophysics Data System (ADS)

Yang, Yong-fa; Li, Qi

2014-12-01

In the practical application of terahertz reflection-mode confocal scanning microscopy, the size of detector pinhole is an important factor that determines the performance of spatial resolution characteristic of the microscopic system. However, the use of physical pinhole brings some inconvenience to the experiment and the adjustment error has a great influence on the experiment result. Through reasonably selecting the parameter of matrix detector virtual pinhole (VPH), it can efficiently approximate the physical pinhole. By using this approach, the difficulty of experimental calibration is reduced significantly. In this article, an imaging scheme of terahertz reflection-mode confocal scanning microscopy that is based on the matrix detector VPH is put forward. The influence of detector pinhole size on the axial resolution of confocal scanning microscopy is emulated and analyzed. Then, the parameter of VPH is emulated when the best axial imaging performance is reached.

A learning-based autonomous driver: emulate human driver's intelligence in low-speed car following

NASA Astrophysics Data System (ADS)

Wei, Junqing; Dolan, John M.; Litkouhi, Bakhtiar

2010-04-01

In this paper, an offline learning mechanism based on the genetic algorithm is proposed for autonomous vehicles to emulate human driver behaviors. The autonomous driving ability is implemented based on a Prediction- and Cost function-Based algorithm (PCB). PCB is designed to emulate a human driver's decision process, which is modeled as traffic scenario prediction and evaluation. This paper focuses on using a learning algorithm to optimize PCB with very limited training data, so that PCB can have the ability to predict and evaluate traffic scenarios similarly to human drivers. 80 seconds of human driving data was collected in low-speed (< 30miles/h) car-following scenarios. In the low-speed car-following tests, PCB was able to perform more human-like carfollowing after learning. A more general 120 kilometer-long simulation showed that PCB performs robustly even in scenarios that are not part of the training set.

Compact first and second order polarization mode dispersion emulator

NASA Astrophysics Data System (ADS)

Zhang, Yang; Li, Shiguang; Yang, Changxi

2005-08-01

We propose a 1st and 2nd order polarization mode dispersion emulator (PMDE) with one variable differential group delay (DGD) element using birefringence crystals and four polarization controllers (PCs). Monte Carlo simulations demonstrate that the output 1st and 2nd order polarization mode dispersion (PMD) generated by the PMDE consists with statistic theory. Compared with former PMDEs, this design is tunable, lower-cost, and more integrated for fabrication, which shows response time of 150 ?s, response frequency of 3.8 kHz, working wavelength of 1550 nm, total power consumption of less than 3 W, working range of 0---84 ps and 0---3600 ps2 for 1st and 2nd order PMD emulation, respectively. Also, it is programmable and can be controlled by either singlechip or computer. It can be applied to study the outage probability of optical communication systems due to PMD effect and the effectiveness of PMD compensation.

Beamforming synthesis of binaural responses from computer simulations of acoustic spaces.

PubMed

Poletti, Mark A; Svensson, U Peter

2008-07-01

Auditorium designs can be evaluated prior to construction by numerical modeling of the design. High-accuracy numerical modeling produces the sound pressure on a rectangular grid, and subjective assessment of the design requires auralization of the sampled sound field at a desired listener position. This paper investigates the production of binaural outputs from the sound pressure at a selected number of grid points by using a least squares beam forming approach. Low-frequency axisymmetric emulations are derived by assuming a solid sphere model of the head, and a spherical array of 640 microphones is used to emulate ten measured head-related transfer function (HRTF) data sets from the CIPIC database for half the audio bandwidth. The spherical array can produce high-accuracy band-limited emulation of any human subject's measured HRTFs for a fixed listener position by using individual sets of beam forming impulse responses.

Simulation/Emulation Techniques: Compressing Schedules With Parallel (HW/SW) Development

NASA Technical Reports Server (NTRS)

Mangieri, Mark L.; Hoang, June

2014-01-01

NASA has always been in the business of balancing new technologies and techniques to achieve human space travel objectives. NASA's Kedalion engineering analysis lab has been validating and using many contemporary avionics HW/SW development and integration techniques, which represent new paradigms to NASA's heritage culture. Kedalion has validated many of the Orion HW/SW engineering techniques borrowed from the adjacent commercial aircraft avionics solution space, inserting new techniques and skills into the Multi - Purpose Crew Vehicle (MPCV) Orion program. Using contemporary agile techniques, Commercial-off-the-shelf (COTS) products, early rapid prototyping, in-house expertise and tools, and extensive use of simulators and emulators, NASA has achieved cost effective paradigms that are currently serving the Orion program effectively. Elements of long lead custom hardware on the Orion program have necessitated early use of simulators and emulators in advance of deliverable hardware to achieve parallel design and development on a compressed schedule.

Emulating weak localization using a solid-state quantum circuit.

PubMed

Chen, Yu; Roushan, P; Sank, D; Neill, C; Lucero, Erik; Mariantoni, Matteo; Barends, R; Chiaro, B; Kelly, J; Megrant, A; Mutus, J Y; O'Malley, P J J; Vainsencher, A; Wenner, J; White, T C; Yin, Yi; Cleland, A N; Martinis, John M

2014-10-14

Quantum interference is one of the most fundamental physical effects found in nature. Recent advances in quantum computing now employ interference as a fundamental resource for computation and control. Quantum interference also lies at the heart of sophisticated condensed matter phenomena such as Anderson localization, phenomena that are difficult to reproduce in numerical simulations. Here, employing a multiple-element superconducting quantum circuit, with which we manipulate a single microwave photon, we demonstrate that we can emulate the basic effects of weak localization. By engineering the control sequence, we are able to reproduce the well-known negative magnetoresistance of weak localization as well as its temperature dependence. Furthermore, we can use our circuit to continuously tune the level of disorder, a parameter that is not readily accessible in mesoscopic systems. Demonstrating a high level of control, our experiment shows the potential for employing superconducting quantum circuits as emulators for complex quantum phenomena.

[Long-term treatment with a low-molecular-weight heparin administered subcutaneously compared with a vitamin K antagonist: subanalysis of patients with cancer].

PubMed

Romera-Villegas, Antonio; Martí Mestre, Xavier; Vila Coll, Ramón; Colomé Nafría, Esteve

2015-01-01

We performed a subanalysis of cancer patients enrolled in a clinical trial that compared long-term (6 months) treatment with a low-molecular-weight heparin (LMWH) administered subcutaneously or with acenocoumarol. The subanalysis assessed whether the characteristics of the tumor had an influence on the clinical response. A randomized open trial included 69 patients with cancer and symptomatic proximal deep vein thrombosis of the lower limbs. The tumor characteristics and treatment type were recorded. The main assessment criterion was the 12-month incidence of recurrent symptomatic venous thromboembolism (VTE). Sixty-one patients (88.4%) were analyzed. At the time of inclusion, the cancer characteristics and treatment were comparable between the 2 groups. Over the course of 12 months, the recurrent VTE was significantly greater in the elderly patients (71.5 ± 6.4 vs. 62.0 ± 15.1; p=.006). The logistic regression analysis showed no association between VTE recurrence and the location or extent of the tumor. However, the use of thrombogenic chemotherapy (p=.045) was independently associated with VTE recurrence, and longterm treatment with tinzaparin was almost a protective factor (p=.15). In this small sample, we observed an association between thrombogenic chemotherapy and recurrent VTE. The tendency towards a reduction in VTE recurrence at 12 months in patients with cancer in the LMWH group could be attributed to the effect of the full LMWH dosage. Copyright © 2015 Elsevier España, S.L.U. All rights reserved.

Relationship between flow and incidence of thrombosis in polytetrafluoroethylene vascular grafts in free microvascular flaps in lambs.

PubMed

Paloma, V; Lasso, J M; Bazán, A; Serra, J M

1999-09-01

We have done an experimental study in lambs in which we investigated the influence of flow rate on free microvascular flaps using polytetrafluoroethylene (PTFE) vascular grafts. We set up five surgical groups in which blood flow was progressively increased through the PTFE vascular graft. In group I (venous autograft) we observed just one vascular thrombosis which was located at the site of the anastomosis. In group II (PTFE 3 x 10 mm) all the microvascular flaps became necrosed after the third postoperative day. In group III (PTFE 3 x 10 mm) necrosis also developed in all cases, but the anastomoses remained permeable no longer than eight days. In group IV (3 x 15 mm) the permeability in the microvascular free flaps was about 40% after 21 days, and in group V (3 x 10 mm) it reached 70%. To match graft flow rates with flap survival we did a regression analysis of flow rates for groups II, III, and V and the corresponding survival periods for the flaps. There was a clear and highly significant relationship (r = 0.717, p = 0.0001). In conclusion, it is necessary to maintain blood flow through the prosthesis at a rate higher than the thrombogenic threshold. When the flow rate in the vessels through the PTFE grafts was higher, the viability of the flaps was better. The ideal surgical technique should always be based on an arteriovenous fistula distal to the PTFE vascular graft. It is necessary to maintain blood flow through a prosthesis at a rate higher than the thrombogenic threshold.

In Vitro Microfluidic Models for Neurodegenerative Disorders.

PubMed

Osaki, Tatsuya; Shin, Yoojin; Sivathanu, Vivek; Campisi, Marco; Kamm, Roger D

2018-01-01

Microfluidic devices enable novel means of emulating neurodegenerative disease pathophysiology in vitro. These organ-on-a-chip systems can potentially reduce animal testing and substitute (or augment) simple 2D culture systems. Reconstituting critical features of neurodegenerative diseases in a biomimetic system using microfluidics can thereby accelerate drug discovery and improve our understanding of the mechanisms of several currently incurable diseases. This review describes latest advances in modeling neurodegenerative diseases in the central nervous system and the peripheral nervous system. First, this study summarizes fundamental advantages of microfluidic devices in the creation of compartmentalized cell culture microenvironments for the co-culture of neurons, glial cells, endothelial cells, and skeletal muscle cells and in their recapitulation of spatiotemporal chemical gradients and mechanical microenvironments. Then, this reviews neurodegenerative-disease-on-a-chip models focusing on Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Finally, this study discusses about current drawbacks of these models and strategies that may overcome them. These organ-on-chip technologies can be useful to be the first line of testing line in drug development and toxicology studies, which can contribute significantly to minimize the phase of animal testing steps. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Obstacle Avoidance and Target Acquisition for Robot Navigation Using a Mixed Signal Analog/Digital Neuromorphic Processing System

PubMed Central

Milde, Moritz B.; Blum, Hermann; Dietmüller, Alexander; Sumislawska, Dora; Conradt, Jörg; Indiveri, Giacomo; Sandamirskaya, Yulia

2017-01-01

Neuromorphic hardware emulates dynamics of biological neural networks in electronic circuits offering an alternative to the von Neumann computing architecture that is low-power, inherently parallel, and event-driven. This hardware allows to implement neural-network based robotic controllers in an energy-efficient way with low latency, but requires solving the problem of device variability, characteristic for analog electronic circuits. In this work, we interfaced a mixed-signal analog-digital neuromorphic processor ROLLS to a neuromorphic dynamic vision sensor (DVS) mounted on a robotic vehicle and developed an autonomous neuromorphic agent that is able to perform neurally inspired obstacle-avoidance and target acquisition. We developed a neural network architecture that can cope with device variability and verified its robustness in different environmental situations, e.g., moving obstacles, moving target, clutter, and poor light conditions. We demonstrate how this network, combined with the properties of the DVS, allows the robot to avoid obstacles using a simple biologically-inspired dynamics. We also show how a Dynamic Neural Field for target acquisition can be implemented in spiking neuromorphic hardware. This work demonstrates an implementation of working obstacle avoidance and target acquisition using mixed signal analog/digital neuromorphic hardware. PMID:28747883

Pursuing Polymer Dielectric Interfacial Effect in Organic Transistors for Photosensing Performance Optimization.

PubMed

Wu, Xiaohan; Chu, Yingli; Liu, Rui; Katz, Howard E; Huang, Jia

2017-12-01

Polymer dielectrics in organic field-effect transistors (OFETs) are essential to provide the devices with overall flexibility, stretchability, and printability and simultaneously introduce charge interaction on the interface with organic semiconductors (OSCs). The interfacial effect between various polymer dielectrics and OSCs significantly and intricately influences device performance. However, understanding of this effect is limited because the interface is buried and the interfacial charge interaction is difficult to stimulate and characterize. Here, this challenge is overcome by utilizing illumination to stimulate the interfacial effect in various OFETs and to characterize the responses of the effect by measuring photoinduced changes of the OFETs performances. This systemic investigation reveals the mechanism of the intricate interfacial effect in detail, and mathematically explains how the photosensitive OFETs characteristics are determined by parameters including polar group of the polymer dielectric and the OSC side chain. By utilizing this mechanism, performance of organic electronics can be precisely controlled and optimized. OFETs with strong interfacial effect can also show a signal additivity caused by repeated light pulses, which is applicable for photostimulated synapse emulator. Therefore, this work enlightens a detailed understanding on the interface effect and provides novel strategies for optimizing OFET photosensory performances.

Bilateral control in teleoperation of a rehabilitation robot

NASA Astrophysics Data System (ADS)

Rahman, Tariq; Harwin, William S.

1993-03-01

One applications of teleoperation principles is of a manipulator that might be used to augment function in a disabled person. An individual with a paralyzing injury may have complete loss of motor and sensory function in his or her arms, which limits his or her ability to interact with the environment and perform simple tasks such as feeding or turning pages. One way of enhancing functionality is to employ a telemanipulator that might take the place of a care giver, thus providing the person with increased independence. This paper describes how a high level spinal cord injured individual would use head movement to control a robot. It is felt that the key to successful manipulation is in attaining a sense of force and position proprioception. This natural proprioception exists in cable operated prosthetic arms and simple tools such as mouthsticks or laser beam pointers where the user is physically linked to the device. This sense of proprioception is being emulated using a head controlled master-slave arrangement. The goal is for the disabled individual to operate a manipulator and utilize proprioceptive as well as visual feedback. This would lessen the mental burden on the user and ultimately make the device more acceptable.

Obstacle Avoidance and Target Acquisition for Robot Navigation Using a Mixed Signal Analog/Digital Neuromorphic Processing System.

PubMed

Milde, Moritz B; Blum, Hermann; Dietmüller, Alexander; Sumislawska, Dora; Conradt, Jörg; Indiveri, Giacomo; Sandamirskaya, Yulia

2017-01-01

Neuromorphic hardware emulates dynamics of biological neural networks in electronic circuits offering an alternative to the von Neumann computing architecture that is low-power, inherently parallel, and event-driven. This hardware allows to implement neural-network based robotic controllers in an energy-efficient way with low latency, but requires solving the problem of device variability, characteristic for analog electronic circuits. In this work, we interfaced a mixed-signal analog-digital neuromorphic processor ROLLS to a neuromorphic dynamic vision sensor (DVS) mounted on a robotic vehicle and developed an autonomous neuromorphic agent that is able to perform neurally inspired obstacle-avoidance and target acquisition. We developed a neural network architecture that can cope with device variability and verified its robustness in different environmental situations, e.g., moving obstacles, moving target, clutter, and poor light conditions. We demonstrate how this network, combined with the properties of the DVS, allows the robot to avoid obstacles using a simple biologically-inspired dynamics. We also show how a Dynamic Neural Field for target acquisition can be implemented in spiking neuromorphic hardware. This work demonstrates an implementation of working obstacle avoidance and target acquisition using mixed signal analog/digital neuromorphic hardware.

Feasibility and performance evaluation of generating and recording visual evoked potentials using ambulatory Bluetooth based system.

PubMed

Ellingson, Roger M; Oken, Barry

2010-01-01

Report contains the design overview and key performance measurements demonstrating the feasibility of generating and recording ambulatory visual stimulus evoked potentials using the previously reported custom Complementary and Alternative Medicine physiologic data collection and monitoring system, CAMAS. The methods used to generate visual stimuli on a PDA device and the design of an optical coupling device to convert the display to an electrical waveform which is recorded by the CAMAS base unit are presented. The optical sensor signal, synchronized to the visual stimulus emulates the brain's synchronized EEG signal input to CAMAS normally reviewed for the evoked potential response. Most importantly, the PDA also sends a marker message over the wireless Bluetooth connection to the CAMAS base unit synchronized to the visual stimulus which is the critical averaging reference component to obtain VEP results. Results show the variance in the latency of the wireless marker messaging link is consistent enough to support the generation and recording of visual evoked potentials. The averaged sensor waveforms at multiple CPU speeds are presented and demonstrate suitability of the Bluetooth interface for portable ambulatory visual evoked potential implementation on our CAMAS platform.

Effect of multi-wavelength irradiation on color characterization with light-emitting diodes (LEDs)

NASA Astrophysics Data System (ADS)

Park, Hyeong Ju; Song, Woosub; Lee, Byeong-Il; Kim, Hyejin; Kang, Hyun Wook

2017-06-01

In the current study, a multi-wavelength light-emitting diode (LED)-integrated CMOS imaging device was developed to investigate the effect of various wavelengths on multiple color characterization. Various color pigments (black, red, green, and blue) were applied on both white paper and skin phantom surfaces for quantitative analysis. The artificial skin phantoms were made of polydimethylsiloxane (PDMS) mixed with coffee and TiO2 powder to emulate the optical properties of the human dermis. The customized LED-integrated imaging device acquired images of the applied pigments by sequentially irradiating with the LED lights in the order of white, red, green, and blue. Each color pigment induced a lower contrast during illumination by the light with the equivalent color. However, the illumination by light with the complementary (opposite) color increased the signal-to-noise ratio by up to 11-fold due to the formation of a strong contrast ( i.e., red LED = 1.6 ± 0.3 vs. green LED = 19.0 ± 0.6 for red pigment). Detection of color pigments in conjunction with multi-wavelength LEDs can be a simple and reliable technique to estimate variations in the color pigments quantitatively.

Preferred Molecular Orientation of Coumarin 343 on TiO 2 Surfaces: Application to Dye-Sensitized Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCree-Grey, Jonathan; Cole, Jacqueline M.; Evans, Peter J.

2015-07-21

The dye…TiO2 interfacial structure in working electrodes of dye-sensitized solar cells (DSCs) is known to influence its photovoltaic device performance. Despite this, direct and quantitative reports of such structure remain sparse. This case study presents the application of X-ray reflectometry to determine the preferred structural orientation and molecular packing of the organic dye, coumarin 343, adsorbed onto amorphous TiO2. Results show that the dye molecules are, on average, tilted by 61.1° relative to the TiO2 surface, and are separated from each other by 8.2 Å. These findings emulate the molecular packing arrangement of a monolayer of coumarin 343 within itsmore » crystal structure. This suggests that the dye adsorbs onto TiO2 in one of its lowest energy configurations, i.e. dye…TiO2 self assembly is driven more by thermodynamic rather than kinetic means. Complementary DSC device tests illustrate that this interfacial structure compromises photovoltaic performance, unless a suitably sized co-adsorbant is interdispersed between the coumarin 343 chromophores on the TiO2 surface.« less

The development of radioactive sample surrogates for training and exercises

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martha Finck; Bevin Brush; Dick Jansen

2012-03-01

The development of radioactive sample surrogates for training and exercises Source term information is required for to reconstruct a device used in a dispersed radiological dispersal device. Simulating a radioactive environment to train and exercise sampling and sample characterization methods with suitable sample materials is a continued challenge. The Idaho National Laboratory has developed and permitted a Radioactive Response Training Range (RRTR), an 800 acre test range that is approved for open air dispersal of activated KBr, for training first responders in the entry and exit from radioactively contaminated areas, and testing protocols for environmental sampling and field characterization. Membersmore » from the Department of Defense, Law Enforcement, and the Department of Energy participated in the first contamination exercise that was conducted at the RRTR in the July 2011. The range was contaminated using a short lived radioactive Br-82 isotope (activated KBr). Soil samples contaminated with KBr (dispersed as a solution) and glass particles containing activated potassium bromide that emulated dispersed radioactive materials (such as ceramic-based sealed source materials) were collected to assess environmental sampling and characterization techniques. This presentation summarizes the performance of a radioactive materials surrogate for use as a training aide for nuclear forensics.« less

Validation of Bioreactor and Human-on-a-Chip Devices for Chemical Safety Assessment.

PubMed

Rebelo, Sofia P; Dehne, Eva-Maria; Brito, Catarina; Horland, Reyk; Alves, Paula M; Marx, Uwe

2016-01-01

Equipment and device qualification and test assay validation in the field of tissue engineered human organs for substance assessment remain formidable tasks with only a few successful examples so far. The hurdles seem to increase with the growing complexity of the biological systems, emulated by the respective models. Controlled single tissue or organ culture in bioreactors improves the organ-specific functions and maintains their phenotypic stability for longer periods of time. The reproducibility attained with bioreactor operations is, per se, an advantage for the validation of safety assessment. Regulatory agencies have gradually altered the validation concept from exhaustive "product" to rigorous and detailed process characterization, valuing reproducibility as a standard for validation. "Human-on-a-chip" technologies applying micro-physiological systems to the in vitro combination of miniaturized human organ equivalents into functional human micro-organisms are nowadays thought to be the most elaborate solution created to date. They target the replacement of the current most complex models-laboratory animals. Therefore, we provide here a road map towards the validation of such "human-on-a-chip" models and qualification of their respective bioreactor and microchip equipment along a path currently used for the respective animal models.

Quantum Emulation of Gravitational Waves

PubMed Central

Fernandez-Corbaton, Ivan; Cirio, Mauro; Büse, Alexander; Lamata, Lucas; Solano, Enrique; Molina-Terriza, Gabriel

2015-01-01

Gravitational waves, as predicted by Einstein’s general relativity theory, appear as ripples in the fabric of spacetime traveling at the speed of light. We prove that the propagation of small amplitude gravitational waves in a curved spacetime is equivalent to the propagation of a subspace of electromagnetic states. We use this result to propose the use of entangled photons to emulate the evolution of gravitational waves in curved spacetimes by means of experimental electromagnetic setups featuring metamaterials. PMID:26169801

The use of emulator-based simulators for on-board software maintenance

NASA Astrophysics Data System (ADS)

Irvine, M. M.; Dartnell, A.

2002-07-01

Traditionally, onboard software maintenance activities within the space sector are performed using hardware-based facilities. These facilities are developed around the use of hardware emulation or breadboards containing target processors. Some sort of environment is provided around the hardware to support the maintenance actives. However, these environments are not easy to use to set-up the required test scenarios, particularly when the onboard software executes in a dynamic I/O environment, e.g. attitude control software, or data handling software. In addition, the hardware and/or environment may not support the test set-up required during investigations into software anomalies, e.g. raise spurious interrupt, fail memory, etc, and the overall "visibility" of the software executing may be limited. The Software Maintenance Simulator (SOMSIM) is a tool that can support the traditional maintenance facilities. The following list contains some of the main benefits that SOMSIM can provide: Low cost flexible extension to existing product - operational simulator containing software processor emulator; System-level high-fidelity test-bed in which software "executes"; Provides a high degree of control/configuration over the entire "system", including contingency conditions perhaps not possible with real hardware; High visibility and control over execution of emulated software. This paper describes the SOMSIM concept in more detail, and also describes the SOMSIM study being carried out for ESA/ESOC by VEGA IT GmbH.

The reflection of evolving bearing faults in the stator current's extended park vector approach for induction machines

NASA Astrophysics Data System (ADS)

Corne, Bram; Vervisch, Bram; Derammelaere, Stijn; Knockaert, Jos; Desmet, Jan

2018-07-01

Stator current analysis has the potential of becoming the most cost-effective condition monitoring technology regarding electric rotating machinery. Since both electrical and mechanical faults are detected by inexpensive and robust current-sensors, measuring current is advantageous on other techniques such as vibration, acoustic or temperature analysis. However, this technology is struggling to breach into the market of condition monitoring as the electrical interpretation of mechanical machine-problems is highly complicated. Recently, the authors built a test-rig which facilitates the emulation of several representative mechanical faults on an 11 kW induction machine with high accuracy and reproducibility. Operating this test-rig, the stator current of the induction machine under test can be analyzed while mechanical faults are emulated. Furthermore, while emulating, the fault-severity can be manipulated adaptively under controllable environmental conditions. This creates the opportunity of examining the relation between the magnitude of the well-known current fault components and the corresponding fault-severity. This paper presents the emulation of evolving bearing faults and their reflection in the Extended Park Vector Approach for the 11 kW induction machine under test. The results confirm the strong relation between the bearing faults and the stator current fault components in both identification and fault-severity. Conclusively, stator current analysis increases reliability in the application as a complete, robust, on-line condition monitoring technology.

Integration of Component Knowledge in Penalized-Likelihood Reconstruction with Morphological and Spectral Uncertainties.

PubMed

Stayman, J Webster; Tilley, Steven; Siewerdsen, Jeffrey H

2014-01-01

Previous investigations [1-3] have demonstrated that integrating specific knowledge of the structure and composition of components like surgical implants, devices, and tools into a model-based reconstruction framework can improve image quality and allow for potential exposure reductions in CT. Using device knowledge in practice is complicated by uncertainties in the exact shape of components and their particular material composition. Such unknowns in the morphology and attenuation properties lead to errors in the forward model that limit the utility of component integration. In this work, a methodology is presented to accommodate both uncertainties in shape as well as unknown energy-dependent attenuation properties of the surgical devices. This work leverages the so-called known-component reconstruction (KCR) framework [1] with a generalized deformable registration operator and modifications to accommodate a spectral transfer function in the component model. Moreover, since this framework decomposes the object into separate background anatomy and "known" component factors, a mixed fidelity forward model can be adopted so that measurements associated with projections through the surgical devices can be modeled with much greater accuracy. A deformable KCR (dKCR) approach using the mixed fidelity model is introduced and applied to a flexible wire component with unknown structure and composition. Image quality advantages of dKCR over traditional reconstruction methods are illustrated in cone-beam CT (CBCT) data acquired on a testbench emulating a 3D-guided needle biopsy procedure - i.e., a deformable component (needle) with strong energy-dependent attenuation characteristics (steel) within a complex soft-tissue background.

Noise Characteristics of a Four-Jet Impingement Device Inside a Broadband Engine Noise Simulator

NASA Technical Reports Server (NTRS)

Brehm, Christoph; Housman, Jeffrey A.; Kiris, Cetin C.; Hutcheson, Florence V.

2015-01-01

The noise generation mechanisms for four directly impinging supersonic jets are investigated employing implicit large eddy simulations with a higher-order accurate weighted essentially non-oscillatory shock-capturing scheme. Impinging jet devices are often used as an experimental apparatus to emulate a broadband noise source. Although such devices have been used in many experiments, a detailed investigation of the noise generation mechanisms has not been conducted before. Thus, the underlying physical mechanisms that are responsible for the generation of sound waves are not well understood. The flow field is highly complex and contains a wide range of temporal and spatial scales relevant for noise generation. Proper orthogonal decomposition of the flow field is utilized to characterize the unsteady nature of the flow field involving unsteady shock oscillations, large coherent turbulent flow structures, and the sporadic appearance of vortex tubes in the center of the impingement region. The causality method based on Lighthill's acoustic analogy is applied to link fluctuations of flow quantities inside the source region to the acoustic pressure in the far field. It will be demonstrated that the entropy fluctuation term in the Lighthill's stress tensor plays a vital role in the noise generation process. Consequently, the understanding of the noise generation mechanisms is employed to develop a reduced-order linear acoustic model of the four-jet impingement device. Finally, three linear acoustic FJID models are used as broadband noise sources inside an engine nacelle and the acoustic scattering results are validated against far-field acoustic experimental data.

From Bench to Bedside: Utility of the Rabbit Elastase Aneurysm Model in Pre-Clinical Studies of Intracranial Aneurysm Treatment

PubMed Central

Brinjikji, Waleed; Ding, Yong H; Kallmes, David F; Kadirvel, Ramanathan

2016-01-01

Summary Pre-clinical studies are important in helping practitioners and device developers improve techniques and tools for endovascular treatment of intracranial aneurysms. Thus, an understanding of the major animal models used in such studies is important. The New Zealand rabbit elastase induced arterial aneurysm of the common carotid artery is one of the most commonly used models in testing the safety and efficacy of new endovascular devices. In this review we discuss 1) various techniques used to create the aneurysm, 2) complications of aneurysm creation, 3) natural history of the arterial aneurysm, 4) histopathologic and hemodynamic features of the aneurysm 5) devices tested using this model and 6) weaknesses of the model. We demonstrate how pre-clinical studies using this model are applied in treatment of intracranial aneurysms in humans. The model has a similar hemodynamic, morphological and histologic characteristics to human aneurysms and demonstrates similar healing responses to coiling as human aneurysms. Despite these strengths however, the model does have many weaknesses including the fact that the model does not emulate the complex inflammatory processes affecting growing and ruptured aneurysms. Furthermore the model’s extracranial location affects its ability to be used in preclinical safety assessments of new devices. We conclude that the rabbit elastase model has characteristics that make it a simple and effective model for preclinical studies on the endovascular treatment of intracranial aneurysms however further work is needed to develop aneurysm models that simulate the histopathologic and morphologic characteristics of growing and ruptured aneurysms. PMID:25904642

Bayesian History Matching of Complex Infectious Disease Models Using Emulation: A Tutorial and a Case Study on HIV in Uganda

PubMed Central

Andrianakis, Ioannis; Vernon, Ian R.; McCreesh, Nicky; McKinley, Trevelyan J.; Oakley, Jeremy E.; Nsubuga, Rebecca N.; Goldstein, Michael; White, Richard G.

2015-01-01

Advances in scientific computing have allowed the development of complex models that are being routinely applied to problems in disease epidemiology, public health and decision making. The utility of these models depends in part on how well they can reproduce empirical data. However, fitting such models to real world data is greatly hindered both by large numbers of input and output parameters, and by long run times, such that many modelling studies lack a formal calibration methodology. We present a novel method that has the potential to improve the calibration of complex infectious disease models (hereafter called simulators). We present this in the form of a tutorial and a case study where we history match a dynamic, event-driven, individual-based stochastic HIV simulator, using extensive demographic, behavioural and epidemiological data available from Uganda. The tutorial describes history matching and emulation. History matching is an iterative procedure that reduces the simulator's input space by identifying and discarding areas that are unlikely to provide a good match to the empirical data. History matching relies on the computational efficiency of a Bayesian representation of the simulator, known as an emulator. Emulators mimic the simulator's behaviour, but are often several orders of magnitude faster to evaluate. In the case study, we use a 22 input simulator, fitting its 18 outputs simultaneously. After 9 iterations of history matching, a non-implausible region of the simulator input space was identified that was times smaller than the original input space. Simulator evaluations made within this region were found to have a 65% probability of fitting all 18 outputs. History matching and emulation are useful additions to the toolbox of infectious disease modellers. Further research is required to explicitly address the stochastic nature of the simulator as well as to account for correlations between outputs. PMID:25569850

HairMax LaserComb laser phototherapy device in the treatment of male androgenetic alopecia: A randomized, double-blind, sham device-controlled, multicentre trial.

PubMed

Leavitt, Matt; Charles, Glenn; Heyman, Eugene; Michaels, David

2009-01-01

The use of low levels of visible or near infrared light for reducing pain, inflammation and oedema, promoting healing of wounds, deeper tissue and nerves, and preventing tissue damage has been known for almost 40 years since the invention of lasers. The HairMax LaserComb is a hand-held Class 3R lower level laser therapy device that contains a single laser module that emulates 9 beams at a wavelength of 655 nm (+/-5%). The device uses a technique of parting the user's hair by combs that are attached to the device. This improves delivery of distributed laser light to the scalp. The combs are designed so that each of the teeth on the combs aligns with a laser beam. By aligning the teeth with the laser beams, the hair can be parted and the laser energy delivered to the scalp of the user without obstruction by the individual hairs on the scalp. The primary aim of the study was to assess the safety and effectiveness of the HairMax LaserComb laser phototherapy device in the promotion of hair growth and in the cessation of hair loss in males diagnosed with androgenetic alopecia (AGA). This double-blind, sham device-controlled, multicentre, 26-week trial randomized male patients with Norwood-Hamilton classes IIa-V AGA to treatment with the HairMax LaserComb or the sham device (2 : 1). The sham device used in the study was identical to the active device except that the laser light was replaced by a non-active incandescent light source. Of the 110 patients who completed the study, subjects in the HairMax LaserComb treatment group exhibited a significantly greater increase in mean terminal hair density than subjects in the sham device group (p < 0.0001). Consistent with this evidence for primary effectiveness, significant improvements in overall hair regrowth were demonstrated in terms of patients' subjective assessment (p < 0.015) at 26 weeks over baseline. The HairMax LaserComb was well tolerated with no serious adverse events reported and no statistical difference in adverse effects between the study groups. The results of this study suggest that the HairMax LaserComb is an effective, well tolerated and safe laser phototherapy device for the treatment of AGA in males.

An abdominal active can defibrillator may facilitate a successful generator change when a lead failure is present.

PubMed

Solomon, A J; Moubarak, J B; Drood, J M; Tracy, C M; Karasik, P E

1999-10-01

Defibrillator generator changes are frequently performed on patients with an implantable cardioverter defibrillator in an abdominal pocket. These patients usually have epicardial patches or older endocardial lead systems. At the time of a defibrillator generator change defibrillation may be unsuccessful as a result of lead failure. We tested the hypothesis that an active can defibrillator implanted in the abdominal pocket could replace a non-functioning endocardial lead or epicardial patch. An abdominal defibrillator generator change was performed in 10 patients, (mean age = 67 +/- 13 years, nine men). Initially, a defibrillation threshold (DFT) was obtained using a passive defibrillator and the chronic endocardial or epicardial lead system. DFTs were then performed using an active can emulator and one chronic lead to simulate endocardial or epicardial lead failure. We tested 30 lead configurations (nine endocardial and 21 epicardial). Although a DFT of 7.3 +/- 4.2 joules was obtained with the intact chronic lead system, the active can emulator and one endocardial or epicardial lead still yielded an acceptable DFT of 19.9 +/- 6.1 joules. In addition, a successful implant (DFT < or = 24 joules) could have been accomplished in 28 of 30 (93%) lead configurations. An active can defibrillator in an abdominal pocket may allow for a successful generator change in patients with defibrillator lead malfunction. This would be simpler than abandoning the abdominal implant and moving to a new pectoral device and lead or tunnelling a new endocardial electrode. However, loss of defibrillation capability with a particular complex lead may be a warning of impending loss of other functions (eg. sensing and/or pacing).

Heparin Induced Thrombocytopenia and Re-Thrombosis Associated with Warfarin and Fondaparinux in a Child

PubMed Central

Maurer, Scott H.; Wilimas, Judith A.; Wang, Winfred C.; Reiss, Ulrike M.

2016-01-01

An 11 year-old female developed heparin induced thrombocytopenia (HIT) with thrombosis during therapy for lower extremity deep vein thrombosis and pulmonary embolism. Transition from bivalirudin, a direct thrombin inhibitor (DTI), to warfarin resulted in extensive re-thrombosis, and fondaparinux therapy similarly failed. She was then treated with argatroban, and transitioned successfully to warfarin after nine weeks. The risk of re-thrombosis was ultimately reduced by allowing time for the thrombogenic potential to abate. The argatroban/warfarin transition was monitored with chromogenic factor X levels. This case highlights several difficult problems in pediatric thrombosis. PMID:19415734

Biomimicry 1: PC.

PubMed

Cumberland, D C; Gunn, J; Malik, N; Holt, C M

1998-01-01

The surface properties of stents can be modified by coating them, for example with a polymer. Phosphorylcoline (PC) is the major component of the outer layer of the cell membrane. The haemo- and biocompatibility of a PC-containing polymer is thus based on biomimicry, and has been confirmed by several experiments showing much reduced thrombogenicity of PC-coated surfaces, and porcine coronary artery implants showing no sign of adverse effect. Clinical experience with the PC-coated BiodivYsio appears favourable. The PC coating can be tailored for take up and controlled elution of various drugs for stent-based local delivery, a property which is being actively explored.

discovery toolset for Emulytics v. 1.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fritz, David; Crussell, Jonathan

The discovery toolset for Emulytics enables the construction of high-fidelity emulation models of systems. The toolset consists of a set of tools and techniques to automatically go from network discovery of operational systems to emulating those complex systems. Our toolset combines data from host discovery and network mapping tools into an intermediate representation that can then be further refined. Once the intermediate representation reaches the desired state, our toolset supports emitting the Emulytics models with varying levels of specificity based on experiment needs.

Implementation of virtual LANs over ATM WANs

NASA Astrophysics Data System (ADS)

Braun, Torsten; Maehler, Martin

1998-09-01

Virtual LANs (VLANs) allow to interconnect users over campus or wide area networks and gives the users the impression as they would be connected to the same local area network (LAN). The implementation of VLANs is based on ATM Forum's LAN Emulation and LAN/ATM switches providing interconnection of emulated LANs over ATM and the LAN ports to which the user's end systems are attached to. The paper discusses possible implementation architectures and describes advanced features such as ATM short-cuts, QoS, and redundancy concepts.

A Low-Cost Part-Task Flight Training System: An Application of a Head Mounted Display

DTIC Science & Technology

1990-12-01

architecture. The task at hand was to develop a software emulation libary that would emulate the function calls used within the Flight and Dog programs. This...represented in two hexadecimal digits for each color. The format of the packed long integer looks like aaggbbrr with each color value representing a...Western Digital ethernet card as the cheapest compatible card available. Good fortune arrived, as I was calling to order the card, I saw an unused card

Cyber integrated MEMS microhand for biological applications

NASA Astrophysics Data System (ADS)

Weissman, Adam; Frazier, Athena; Pepen, Michael; Lu, Yen-Wen; Yang, Shanchieh Jay

2009-05-01

Anthropomorphous robotic hands at microscales have been developed to receive information and perform tasks for biological applications. To emulate a human hand's dexterity, the microhand requires a master-slave interface with a wearable controller, force sensors, and perception displays for tele-manipulation. Recognizing the constraints and complexity imposed in developing feedback interface during miniaturization, this project address the need by creating an integrated cyber environment incorporating sensors with a microhand, haptic/visual display, and object model, to emulates human hands' psychophysical perception at microscale.

8755 Emulator Design

DTIC Science & Technology

1988-12-01

Break Control....................51 8755 I/O Control..................54 Z-100 Control Software................. 55 Pass User Memory...the emulator SRAM and the other is 55 for the target SRAM. If either signal is replaced by the NACK signal the host computer displays an error message...Block Diagram 69 AUU M/M 8 in Fiur[:. cemti Daga 70m F’M I-- ’I ANLAD AMam U52 COMM ow U2 i M.2 " -n ax- U 6_- Figure 2b. Schematic Diagram 71 )-M -A -I

Real time wind farm emulation using SimWindFarm toolbox

NASA Astrophysics Data System (ADS)

Topor, Marcel

2016-06-01

This paper presents a wind farm emulation solution using an open source Matlab/Simulink toolbox and the National Instruments cRIO platform. This work is based on the Aeolus SimWindFarm (SWF) toolbox models developed at Aalborg university, Denmark. Using the Matlab Simulink models developed in SWF, the modeling code can be exported to a real time model using the NI Veristand model framework and the resulting code is integrated as a hardware in the loop control on the NI 9068 platform.

Linear fully dry polymer actuators

NASA Astrophysics Data System (ADS)

De Rossi, Danilo; Mazzoldi, Alberto

1999-05-01

In the last period, the interest in the development of devices that emulate the properties of the 'par excellence' biological actuator, the human muscle, is considerably grown. The recent advances in the field of conducting polymers open new interesting prospects in this direction: from this point of view polyaniline (PANi), since it is easily produced in fiber form, represents an interesting material. In this conference we report the development of a linear actuator prototype that makes use of PANi fiber. All fabrication steps (fiber extrusion, solid polymer electrolyte preparation, compound realization) and experimental set-up for the electromechanical characterization are described. Quantitative measurements of isotonic length changes and isometric stress generation during electrochemical stimulation are reported. An overall assessment of PANi fibers actuative properties in wet and dry conditions is reported and possible future developments are proposed. Finally, continuum and lumped parameter models formulated to describe passive and active contractile properties of conducting polymer actuators are briefly outlined.

Ultrafast Synaptic Events in a Chalcogenide Memristor

NASA Astrophysics Data System (ADS)

Li, Yi; Zhong, Yingpeng; Xu, Lei; Zhang, Jinjian; Xu, Xiaohua; Sun, Huajun; Miao, Xiangshui

2013-04-01

Compact and power-efficient plastic electronic synapses are of fundamental importance to overcoming the bottlenecks of developing a neuromorphic chip. Memristor is a strong contender among the various electronic synapses in existence today. However, the speeds of synaptic events are relatively slow in most attempts at emulating synapses due to the material-related mechanism. Here we revealed the intrinsic memristance of stoichiometric crystalline Ge2Sb2Te5 that originates from the charge trapping and releasing by the defects. The device resistance states, representing synaptic weights, were precisely modulated by 30 ns potentiating/depressing electrical pulses. We demonstrated four spike-timing-dependent plasticity (STDP) forms by applying programmed pre- and postsynaptic spiking pulse pairs in different time windows ranging from 50 ms down to 500 ns, the latter of which is 105 times faster than the speed of STDP in human brain. This study provides new opportunities for building ultrafast neuromorphic computing systems and surpassing Von Neumann architecture.

Ultrafast synaptic events in a chalcogenide memristor.

PubMed

Li, Yi; Zhong, Yingpeng; Xu, Lei; Zhang, Jinjian; Xu, Xiaohua; Sun, Huajun; Miao, Xiangshui

2013-01-01

Compact and power-efficient plastic electronic synapses are of fundamental importance to overcoming the bottlenecks of developing a neuromorphic chip. Memristor is a strong contender among the various electronic synapses in existence today. However, the speeds of synaptic events are relatively slow in most attempts at emulating synapses due to the material-related mechanism. Here we revealed the intrinsic memristance of stoichiometric crystalline Ge2Sb2Te5 that originates from the charge trapping and releasing by the defects. The device resistance states, representing synaptic weights, were precisely modulated by 30 ns potentiating/depressing electrical pulses. We demonstrated four spike-timing-dependent plasticity (STDP) forms by applying programmed pre- and postsynaptic spiking pulse pairs in different time windows ranging from 50 ms down to 500 ns, the latter of which is 10(5) times faster than the speed of STDP in human brain. This study provides new opportunities for building ultrafast neuromorphic computing systems and surpassing Von Neumann architecture.

Performance evaluation of heart sound cancellation in FPGA hardware implementation for electronic stethoscope.

PubMed

Chao, Chun-Tang; Maneetien, Nopadon; Wang, Chi-Jo; Chiou, Juing-Shian

2014-01-01

This paper presents the design and evaluation of the hardware circuit for electronic stethoscopes with heart sound cancellation capabilities using field programmable gate arrays (FPGAs). The adaptive line enhancer (ALE) was adopted as the filtering methodology to reduce heart sound attributes from the breath sounds obtained via the electronic stethoscope pickup. FPGAs were utilized to implement the ALE functions in hardware to achieve near real-time breath sound processing. We believe that such an implementation is unprecedented and crucial toward a truly useful, standalone medical device in outpatient clinic settings. The implementation evaluation with one Altera cyclone II-EP2C70F89 shows that the proposed ALE used 45% resources of the chip. Experiments with the proposed prototype were made using DE2-70 emulation board with recorded body signals obtained from online medical archives. Clear suppressions were observed in our experiments from both the frequency domain and time domain perspectives.

Integration of analytical instruments with computer scripting.

PubMed

Carvalho, Matheus C

2013-08-01

Automation of laboratory routines aided by computer software enables high productivity and is the norm nowadays. However, the integration of different instruments made by different suppliers is still difficult, because to accomplish it, the user must have knowledge of electronics and/or low-level programming. An alternative approach is to control different instruments without an electronic connection between them, relying only on their software interface on a computer. This can be achieved through scripting, which is the emulation of user operations (mouse clicks and keyboard inputs) on the computer. The main advantages of this approach are its simplicity, which enables people with minimal knowledge of computer programming to employ it, and its universality, which enables the integration of instruments made by different suppliers, meaning that the user is totally free to choose the devices to be integrated. Therefore, scripting can be a useful, accessible, and economic solution for laboratory automation.

Network testbed creation and validation

DOEpatents

Thai, Tan Q.; Urias, Vincent; Van Leeuwen, Brian P.; Watts, Kristopher K.; Sweeney, Andrew John

2017-03-21

Embodiments of network testbed creation and validation processes are described herein. A "network testbed" is a replicated environment used to validate a target network or an aspect of its design. Embodiments describe a network testbed that comprises virtual testbed nodes executed via a plurality of physical infrastructure nodes. The virtual testbed nodes utilize these hardware resources as a network "fabric," thereby enabling rapid configuration and reconfiguration of the virtual testbed nodes without requiring reconfiguration of the physical infrastructure nodes. Thus, in contrast to prior art solutions which require a tester manually build an emulated environment of physically connected network devices, embodiments receive or derive a target network description and build out a replica of this description using virtual testbed nodes executed via the physical infrastructure nodes. This process allows for the creation of very large (e.g., tens of thousands of network elements) and/or very topologically complex test networks.

Control of helicopter rotorblade aerodynamics

NASA Technical Reports Server (NTRS)

Fabunmi, James A.

1991-01-01

The results of a feasibility study of a method for controlling the aerodynamics of helicopter rotorblades using stacks of piezoelectric ceramic plates are presented. A resonant mechanism is proposed for the amplification of the displacements produced by the stack. This motion is then converted into linear displacement for the actuation of the servoflap of the blades. A design which emulates the actuation of the servoflap on the Kaman SH-2F is used to demonstrate the fact that such a system can be designed to produce the necessary forces and velocities needed to control the aerodynamics of the rotorblades of such a helicopter. Estimates of the electrical power requirements are also presented. A Small Business Innovation Research (SBIR) Phase 2 Program is suggested, whereby a bench-top prototype of the device can be built and tested. A collaborative effort between AEDAR Corporation and Kaman Aerospace Corporation is anticipated for future effort on this project.

A simple numerical model for membrane oxygenation of an artificial lung machine

NASA Astrophysics Data System (ADS)

Subraveti, Sai Nikhil; Sai, P. S. T.; Viswanathan Pillai, Vinod Kumar; Patnaik, B. S. V.

2015-11-01

Optimal design of membrane oxygenators will have far reaching ramification in the development of artificial heart-lung systems. In the present CFD study, we simulate the gas exchange between the venous blood and air that passes through the hollow fiber membranes on a benchmark device. The gas exchange between the tube side fluid and the shell side venous liquid is modeled by solving mass, momentum conservation equations. The fiber bundle was modelled as a porous block with a bundle porosity of 0.6. The resistance offered by the fiber bundle was estimated by the standard Ergun correlation. The present numerical simulations are validated against available benchmark data. The effect of bundle porosity, bundle size, Reynolds number, non-Newtonian constitutive relation, upstream velocity distribution etc. on the pressure drop, oxygen saturation levels etc. are investigated. To emulate the features of gas transfer past the alveoli, the effect of pulsatility on the membrane oxygenation is also investigated.

Network testbed creation and validation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thai, Tan Q.; Urias, Vincent; Van Leeuwen, Brian P.

Embodiments of network testbed creation and validation processes are described herein. A "network testbed" is a replicated environment used to validate a target network or an aspect of its design. Embodiments describe a network testbed that comprises virtual testbed nodes executed via a plurality of physical infrastructure nodes. The virtual testbed nodes utilize these hardware resources as a network "fabric," thereby enabling rapid configuration and reconfiguration of the virtual testbed nodes without requiring reconfiguration of the physical infrastructure nodes. Thus, in contrast to prior art solutions which require a tester manually build an emulated environment of physically connected network devices,more » embodiments receive or derive a target network description and build out a replica of this description using virtual testbed nodes executed via the physical infrastructure nodes. This process allows for the creation of very large (e.g., tens of thousands of network elements) and/or very topologically complex test networks.« less

Memristive and neuromorphic behavior in a LixCoO2 nanobattery

NASA Astrophysics Data System (ADS)

Mai, V. H.; Moradpour, A.; Senzier, P. Auban; Pasquier, C.; Wang, K.; Rozenberg, M. J.; Giapintzakis, J.; Mihailescu, C. N.; Orfanidou, C. M.; Svoukis, E.; Breza, A.; Lioutas, Ch B.; Franger, S.; Revcolevschi, A.; Maroutian, T.; Lecoeur, P.; Aubert, P.; Agnus, G.; Salot, R.; Albouy, P. A.; Weil, R.; Alamarguy, D.; March, K.; Jomard, F.; Chrétien, P.; Schneegans, O.

2015-01-01

The phenomenon of resistive switching (RS), which was initially linked to non-volatile resistive memory applications, has recently also been associated with the concept of memristors, whose adjustable multilevel resistance characteristics open up unforeseen perspectives in cognitive computing. Herein, we demonstrate that the resistance states of LixCoO2 thin film-based metal-insulator-metal (MIM) solid-state cells can be tuned by sequential programming voltage pulses, and that these resistance states are dramatically dependent on the pulses input rate, hence emulating biological synapse plasticity. In addition, we identify the underlying electrochemical processes of RS in our MIM cells, which also reveal a nanobattery-like behavior, leading to the generation of electrical signals that bring an unprecedented new dimension to the connection between memristors and neuromorphic systems. Therefore, these LixCoO2-based MIM devices allow for a combination of possibilities, offering new perspectives of usage in nanoelectronics and bio-inspired neuromorphic circuits.

Emulation: A fast stochastic Bayesian method to eliminate model space

NASA Astrophysics Data System (ADS)

Roberts, Alan; Hobbs, Richard; Goldstein, Michael

2010-05-01

Joint inversion of large 3D datasets has been the goal of geophysicists ever since the datasets first started to be produced. There are two broad approaches to this kind of problem, traditional deterministic inversion schemes and more recently developed Bayesian search methods, such as MCMC (Markov Chain Monte Carlo). However, using both these kinds of schemes has proved prohibitively expensive, both in computing power and time cost, due to the normally very large model space which needs to be searched using forward model simulators which take considerable time to run. At the heart of strategies aimed at accomplishing this kind of inversion is the question of how to reliably and practicably reduce the size of the model space in which the inversion is to be carried out. Here we present a practical Bayesian method, known as emulation, which can address this issue. Emulation is a Bayesian technique used with considerable success in a number of technical fields, such as in astronomy, where the evolution of the universe has been modelled using this technique, and in the petroleum industry where history matching is carried out of hydrocarbon reservoirs. The method of emulation involves building a fast-to-compute uncertainty-calibrated approximation to a forward model simulator. We do this by modelling the output data from a number of forward simulator runs by a computationally cheap function, and then fitting the coefficients defining this function to the model parameters. By calibrating the error of the emulator output with respect to the full simulator output, we can use this to screen out large areas of model space which contain only implausible models. For example, starting with what may be considered a geologically reasonable prior model space of 10000 models, using the emulator we can quickly show that only models which lie within 10% of that model space actually produce output data which is plausibly similar in character to an observed dataset. We can thus much more tightly constrain the input model space for a deterministic inversion or MCMC method. By using this technique jointly on several datasets (specifically seismic, gravity, and magnetotelluric (MT) describing the same region), we can include in our modelling uncertainties in the data measurements, the relationships between the various physical parameters involved, as well as the model representation uncertainty, and at the same time further reduce the range of plausible models to several percent of the original model space. Being stochastic in nature, the output posterior parameter distributions also allow our understanding of/beliefs about a geological region can be objectively updated, with full assessment of uncertainties, and so the emulator is also an inversion-type tool in it's own right, with the advantage (as with any Bayesian method) that our uncertainties from all sources (both data and model) can be fully evaluated.

A Phase-Locked Loop Epilepsy Network Emulator.

PubMed

Watson, P D; Horecka, K M; Cohen, N J; Ratnam, R

2016-10-15

Most seizure forecasting employs statistical learning techniques that lack a representation of the network interactions that give rise to seizures. We present an epilepsy network emulator (ENE) that uses a network of interconnected phase-locked loops (PLLs) to model synchronous, circuit-level oscillations between electrocorticography (ECoG) electrodes. Using ECoG data from a canine-epilepsy model (Davis et al. 2011) and a physiological entropy measure (approximate entropy or ApEn, Pincus 1995), we demonstrate the entropy of the emulator phases increases dramatically during ictal periods across all ECoG recording sites and across all animals in the sample. Further, this increase precedes the observable voltage spikes that characterize seizure activity in the ECoG data. These results suggest that the ENE is sensitive to phase-domain information in the neural circuits measured by ECoG and that an increase in the entropy of this measure coincides with increasing likelihood of seizure activity. Understanding this unpredictable phase-domain electrical activity present in ECoG recordings may provide a target for seizure detection and feedback control.

Evaluation Applied to Reliability Analysis of Reconfigurable, Highly Reliable, Fault-Tolerant, Computing Systems for Avionics

NASA Technical Reports Server (NTRS)

Migneault, G. E.

1979-01-01

Emulation techniques are proposed as a solution to a difficulty arising in the analysis of the reliability of highly reliable computer systems for future commercial aircraft. The difficulty, viz., the lack of credible precision in reliability estimates obtained by analytical modeling techniques are established. The difficulty is shown to be an unavoidable consequence of: (1) a high reliability requirement so demanding as to make system evaluation by use testing infeasible, (2) a complex system design technique, fault tolerance, (3) system reliability dominated by errors due to flaws in the system definition, and (4) elaborate analytical modeling techniques whose precision outputs are quite sensitive to errors of approximation in their input data. The technique of emulation is described, indicating how its input is a simple description of the logical structure of a system and its output is the consequent behavior. The use of emulation techniques is discussed for pseudo-testing systems to evaluate bounds on the parameter values needed for the analytical techniques.

Input current shaped ac-to-dc converters

NASA Technical Reports Server (NTRS)

1985-01-01

Input current shaping techniques for ac-to-dc converters were investigated. Input frequencies much higher than normal, up to 20 kHz were emphasized. Several methods of shaping the input current waveform in ac-to-dc converters were reviewed. The simplest method is the LC filter following the rectifier. The next simplest method is the resistor emulation approach in which the inductor size is determined by the converter switching frequency and not by the line input frequency. Other methods require complicated switch drive algorithms to construct the input current waveshape. For a high-frequency line input, on the order of 20 kHz, the simple LC cannot be discarded so peremptorily, since the inductor size can be compared with that for the resistor emulation method. In fact, since a dc regulator will normally be required after the filter anyway, the total component count is almost the same as for the resistor emulation method, in which the filter is effectively incorporated into the regulator.

UPEML Version 2. 0: A machine-portable CDC Update emulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehlhorn, T.A.; Young, M.F.

1987-05-01

UPEML is a machine-portable CDC Update emulation program. UPEML is written in ANSI standard Fortran-77 and is relatively simple and compact. It is capable of emulating a significant subset of the standard CDC Update functions, including program library creation and subsequent modification. Machine-portability is an essential attribute of UPEML. UPEML was written primarily to facilitate the use of CDC-based scientific packages on alternate computer systems such as the VAX 11/780 and the IBM 3081. UPEML has also been successfully used on the multiprocessor ELXSI, on CRAYs under both COS and CTSS operating systems, on APOLLO workstations, and on the HP-9000.more » Version 2.0 includes enhanced error checking, full ASCI character support, a program library audit capability, and a partial update option in which only selected or modified decks are written to the compile file. Further enhancements include checks for overlapping corrections, processing of nested calls to common decks, and reads and addfiles from alternate input files.« less

Measurement of fault latency in a digital avionic miniprocessor

NASA Technical Reports Server (NTRS)

Mcgough, J. G.; Swern, F. L.

1981-01-01

The results of fault injection experiments utilizing a gate-level emulation of the central processor unit of the Bendix BDX-930 digital computer are presented. The failure detection coverage of comparison-monitoring and a typical avionics CPU self-test program was determined. The specific tasks and experiments included: (1) inject randomly selected gate-level and pin-level faults and emulate six software programs using comparison-monitoring to detect the faults; (2) based upon the derived empirical data develop and validate a model of fault latency that will forecast a software program's detecting ability; (3) given a typical avionics self-test program, inject randomly selected faults at both the gate-level and pin-level and determine the proportion of faults detected; (4) determine why faults were undetected; (5) recommend how the emulation can be extended to multiprocessor systems such as SIFT; and (6) determine the proportion of faults detected by a uniprocessor BIT (built-in-test) irrespective of self-test.

3D velocity field characterization of prosthetic heart valve with two different valve testers by means of stereo-PIV.

PubMed

D'Avenio, Giuseppe; Grigioni, Mauro; Daniele, Carla; Morbiducci, Umberto; Hamilton, Kathrin

2015-01-01

Prosthetic heart valves can be associated to mechanical loading of blood, potentially linked to complications (hemolysis and thrombogenicity) which can be clinically relevant. In order to test such devices in pulsatile mode, pulse duplicators (PDs) have been designed and built according to different concepts. This study was carried out to compare anemometric measurements made on the same prosthetic device, with two widely used PDs. The valve (a 27-mm bileaflet valve) was mounted in the aortic section of the PD. The Sheffield University PD and the RWTH Aachen PD were selected as physical models of the circulation. These two PDs differ mainly in the vertical vs horizontal realization, and in the ventricular section, which in the RWTH PD allows for storage of potential energy in the elastic walls of the ventricle. A glassblown aorta, realized according to the geometric data of the same anatomical district in healthy individuals, was positioned downstream of the valve, obtaining 1:1 geometric similarity conditions. A NaI-glycerol-water solution of suitable kinematic viscosity and, at the same time, the proper refractive index, was selected. The flow field downstream of the valve was measured by means of the stereo-PIV (Particle Image Velocimetry) technique, capable of providing the complete 3D velocity field as well as the entire Reynolds stress tensor. The measurements were carried out at the plane intersecting the valve axis. A three-jet profile was clearly found in the plane crossing the leaflets, with both PDs. The extent of the typical recirculation zone in the Valsalva sinus was much larger in the RWTH PD, on account of the different duration of the swirling motion in the ventricular chamber, caused by the elasticity of the ventricle and its geometry. The comparison of the hemodynamical behaviour of the same bileaflet valve tested in two PDs demonstrated the role of the mock loop in affecting the valve performance.

Agricultural response functions to changes in carbon, temperature, and water based on the C3MP data set

NASA Astrophysics Data System (ADS)

Snyder, A.; Ruane, A. C.; Phillips, M.; Calvin, K. V.; Clarke, L.

2017-12-01

Agricultural yields vary depending on temperature, precipitation/irrigation conditions, fertilizer application, and CO2 concentration. The Coordinated Climate-Crop Modeling Project (C3MP), conducted as a component of the Agricultural Model Intercomparison and Improvement Project (AgMIP), organized a sensitivity experiments across carbon-temperature-water (CTW) space across 1100 management conditions in 50+ countries, sampling 15 crop species and 20 crop models. Such coordinated sensitivity tests allow for the building of emulators of yield response to changes in CTW values, allowing rapid estimation of yield changes from the types of climate changes projected by the climate modeling community. The resulting emulator may be used to supply agricultural responses to climate change in any user-defined scenario, rather than the restriction to the RCPs in many past works. We present the resulting emulators built from the C3MP output data set for use in the Global Change Assessment Model (GCAM) integrated assessment model that allows for the co-evolution of socioeconomic development, greenhouse gas emissions, climate change, and agricultural sector ramifications. C3MP-based emulators may be of use in designing agricultural impact studies in other IAMs, and we place them in the context of past crop modeling efforts, including the Challinor et al. Meta-analysis, the AgMIP Wheat team results, the AgMIP Global Gridded Crop Model Intercomparison (GGCMI) fast-track modeling results, and the MACSUR impact response surface results.

Design and Modeling of a Test Bench for Dual-Motor Electric Drive Tracked Vehicles Based on a Dynamic Load Emulation Method.

PubMed

Wang, Zhe; Lv, Haoliang; Zhou, Xiaojun; Chen, Zhaomeng; Yang, Yong

2018-06-21

Dual-motor Electric Drive Tracked Vehicles (DDTVs) have attracted increasing attention due to their high transmission efficiency and economical fuel consumption. A test bench for the development and validation of new DDTV technologies is necessary and urgent. How to load the vehicle on a DDTV test bench exactly the same as on a real road is a crucial issue when designing the bench. This paper proposes a novel dynamic load emulation method to address this problem. The method adopts dual dynamometers to simulate both the road load and the inertia load that are imposed on the dual independent drive systems. The vehicle’s total inertia equivalent to the drive wheels is calculated with separate consideration of vehicle body, tracks and road wheels to obtain a more accurate inertia load. A speed tracking control strategy with feedforward compensation is implemented to control the dual dynamometers, so as to make the real-time dynamic load emulation possible. Additionally, a MATLAB/Simulink model of the test bench is built based on a dynamics analysis of the platform. Experiments are finally carried out on this test bench under different test conditions. The outcomes show that the proposed load emulation method is effective, and has good robustness and adaptability to complex driving conditions. Besides, the accuracy of the established test bench model is also demonstrated by comparing the results obtained from the simulation model and experiments.

Conception et mise au point d'un emulateur de machine Synchrone trapezoidale a aimants permanents

NASA Astrophysics Data System (ADS)

Lessard, Francois

The development of technology leads inevitably to higher systems' complexity faced by engineers. Over time, tools are often developed in parallel with the main systems to ensure their sustainability. The work presented in this document provides a new tool for testing motor drives. In general, this project refers to active loads, which are complex dynamic loads emulated electronically with a static converter. Specifically, this document proposes and implements a system whose purpose is to recreate the behaviour of a trapezoidal permanent magnets synchronous machine. The ultimate goal is to connect a motor drive to the three terminal of the motor emulator, as it would with a real motor. The emulator's response then obtained, when subjected to disturbances of the motor drive, is ideally identical to the one of a real motor. The motor emulator led to a significant versatility of a test bench because the electrical and mechanical parameters of the application can be easily modified. The work is divided into two main parts: the static converter and real-rime. Overall, these two entities form a PHIL (Power Hardware-in-the-loop) real-time simulation. The static converter enables the exchange of real power between the drive motor and the real-time simulation. The latter gives the application the intelligence needed to interact with the motor drive in a way which the desired behaviour is recreated. The main partner of this project, Opal-RT, ensures this development. Keywords: virtual machine, PHIL, real-time simulation, electronic load

EVAHEART: an implantable centrifugal blood pump for long-term circulatory support.

PubMed

Yamazaki, Kenji; Kihara, Shinichiro; Akimoto, Takehide; Tagusari, Osamu; Kawai, Akihiko; Umezu, Mitsuo; Tomioka, Jun; Kormos, Robert L; Griffith, Bartley P; Kurosawa, Hiromi

2002-11-01

We developed "EVAHEART": a compact centrifugal blood pump system as an implantable left ventricular assist device for long-term circulatory support. The 55 x 64 mm pump is made from pure titanium, and weighs 370 g. The entire blood-contacting surface is covered with an anti-thrombogenic coating of diamond like carbon (DLC) or 2-methacryloyloxyethyl phosphorylcholine (MPC) to improve blood compatibility. Flows exceeding 12 L/min against 100 mmHg pressure at 2600 rpm was measured. A low-temperature mechanical seal with recirculating cooling system is used to seal the shaft. EVAHEART demonstrated an acceptably low hemolysis rate with normalized index of hemolysis of 0.005 +/- 0.002 g/100L. We evaluated the pump in long-term in-vivo experiments with seven calves. Via left thoracotomy, we conducted left ventricular apex-descending aorta bypass, placing the pump in the left thoracic cavity. Pump flow rates was maintained at 5-9 L/min, pump power consumption remained stable at 9-10 W in all cases, plasma free Hb levels were less than 15 mg/dl, and the seal system showed good seal capability throughout the experiments. The calves were sacrificed on schedule on postoperative day 200, 222, 142, 90, 151, 155, and 133. No thrombi formed on the blood contacting surface with either the DLC or MPC coating, and no major organ thromboembolisms occurred except for a few small renal infarcts. EVAHEART centrifugal blood pump demonstrated excellent performance in long-term in-vivo experiments.

Characterization of platelet adhesion under flow using microscopic image sequence analysis.

PubMed

Machin, M; Santomaso, A; Cozzi, M R; Battiston, M; Mazzuccato, M; De Marco, L; Canu, P

2005-07-01

A method for quantitative analysis of platelet deposition under flow is discussed here. The model system is based upon perfusion of blood platelets over an adhesive substrate immobilized on a glass coverslip acting as the lower surface of a rectangular flow chamber. The perfusion apparatus is mounted onto an inverted microscope equipped with epifluorescent illumination and intensified CCD video camera. Characterization is based on information obtained from a specific image analysis method applied to continuous sequences of microscopical images. Platelet recognition across the sequence of images is based on a time-dependent, bidimensional, gaussian-like pdf. Once a platelet is located,the variation of its position and shape as a function of time (i.e., the platelet history) can be determined. Analyzing the history we can establish if the platelet is moving on the surface, the frequency of this movement and the distance traveled before its resumes the velocity of a non-interacting cell. Therefore, we can determine how long the adhesion would last which is correlated to the resistance of the platelet-substrate bond. This algorithm enables the dynamic quantification of trajectories, as well as residence times, arrest and release frequencies for a high numbers of platelets at the same time. Statistically significant conclusions on platelet-surface interactions can then be obtained. An image analysis tool of this kind can dramatically help the investigation and characterization of the thrombogenic properties of artificial surfaces such as those used in artificial organs and biomedical devices.

Electrical muscle stimulation in thomboprophylaxis: review and a derived hypothesis about thrombogenesis-the 4th factor.

PubMed

Stefanou, Christos

2016-01-01

Electrical muscle stimulation (EMS) is an FDA-approved thromboprophylactic method. Thrombus pathogenesis is considered to depend on factors related to components of the vessel wall, the velocity of blood, and blood consistency-collectively known as, the Virchow's triad. The testimony supporting the thromboprophylactic effects of the EMS is reviewed. An emphasis is placed on the fact that, EMS has demonstrated, in certain circumstances, an efficacy rate that cannot be fully explained by the Virchow's triad; also that, in reviewing relevant evidence and the theorized pathophysiological mechanisms, several findings collectively point to a potentially missed point. Remarkably, venous thromboembolic disease (VTE) is extremely more common in the lower versus the upper extremities even when the blood velocities equalize; EMS had synergistic effects with intermittent compressive devices, despite their presumed identical mechanism of action; sleep is not thrombogenic; non-peroperative EMS is meaningful only if applied ≥5 times daily; neural insult increases VTEs more than the degree expected by the hypomobility-related blood stasis; etc. These phenomena infer the presence of a 4th thrombogenetic factor: neural supply to the veins provides direct antithrombic effects, by inducing periodic vessel diameter changes and/or by neuro-humoral, chemically acting factors. EMS may stimulate or substitute the 4th factor. This evidence-based hypothesis is analyzed. A novel pathophysiologic mechanism of thrombogenesis is supported; and, based on this, the role of EMS in thromboprophylaxis is expanded. Exploration of this mechanism may provide new targets for intervention.

FEM design and simulation of a short, 10 MV, S-band Linac with Monte Carlo dose simulations.

PubMed

Baillie, Devin; St Aubin, J; Fallone, B G; Steciw, S

2015-04-01

Current commercial 10 MV Linac waveguides are 1.5 m. The authors' current 6 MV linear accelerator-magnetic resonance imager (Linac-MR) system fits in typical radiotherapy vaults. To allow 10 MV treatments with the Linac-MR and still fit within typical vaults, the authors design a 10 MV Linac with an accelerator waveguide of the same length (27.5 cm) as current 6 MV Linacs. The first design stage is to design a cavity such that a specific experimental measurement for breakdown is applicable to the cavity. This is accomplished through the use of finite element method (FEM) simulations to match published shunt impedance, Q factor, and ratio of peak to mean-axial electric field strength from an electric breakdown study. A full waveguide is then designed and tuned in FEM simulations based on this cavity design. Electron trajectories are computed through the resulting radio frequency fields, and the waveguide geometry is modified by shifting the first coupling cavity in order to optimize the electron beam properties until the energy spread and mean energy closely match values published for an emulated 10 MV Linac. Finally, Monte Carlo dose simulations are used to compare the resulting photon beam depth dose profile and penumbra with that produced by the emulated 10 MV Linac. The shunt impedance, Q factor, and ratio of peak to mean-axial electric field strength are all matched to within 0.1%. A first coupling cavity shift of 1.45 mm produces an energy spectrum width of 0.347 MeV, very close to the published value for the emulated 10 MV of 0.315 MeV, and a mean energy of 10.53 MeV, nearly identical to the published 10.5 MeV for the emulated 10 MV Linac. The depth dose profile produced by their new Linac is within 1% of that produced by the emulated 10 MV spectrum for all depths greater than 1.5 cm. The penumbra produced is 11% narrower, as measured from 80% to 20% of the central axis dose. The authors have successfully designed and simulated an S-band waveguide of length of 27.5 cm capable of producing a 10 MV photon beam. This waveguide operates well within the breakdown threshold determined for the cavity geometry used. The designed Linac produces depth dose profiles similar to those of the emulated 10 MV Linac (waveguide-length of 1.5 m) but yields a narrower penumbra.

FEM design and simulation of a short, 10 MV, S-band Linac with Monte Carlo dose simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baillie, Devin; Aubin, J. St.; Steciw, S., E-mail: ssteciw@ualberta.ca

2015-04-15

Purpose: Current commercial 10 MV Linac waveguides are 1.5 m. The authors’ current 6 MV linear accelerator–magnetic resonance imager (Linac–MR) system fits in typical radiotherapy vaults. To allow 10 MV treatments with the Linac–MR and still fit within typical vaults, the authors design a 10 MV Linac with an accelerator waveguide of the same length (27.5 cm) as current 6 MV Linacs. Methods: The first design stage is to design a cavity such that a specific experimental measurement for breakdown is applicable to the cavity. This is accomplished through the use of finite element method (FEM) simulations to match publishedmore » shunt impedance, Q factor, and ratio of peak to mean-axial electric field strength from an electric breakdown study. A full waveguide is then designed and tuned in FEM simulations based on this cavity design. Electron trajectories are computed through the resulting radio frequency fields, and the waveguide geometry is modified by shifting the first coupling cavity in order to optimize the electron beam properties until the energy spread and mean energy closely match values published for an emulated 10 MV Linac. Finally, Monte Carlo dose simulations are used to compare the resulting photon beam depth dose profile and penumbra with that produced by the emulated 10 MV Linac. Results: The shunt impedance, Q factor, and ratio of peak to mean-axial electric field strength are all matched to within 0.1%. A first coupling cavity shift of 1.45 mm produces an energy spectrum width of 0.347 MeV, very close to the published value for the emulated 10 MV of 0.315 MeV, and a mean energy of 10.53 MeV, nearly identical to the published 10.5 MeV for the emulated 10 MV Linac. The depth dose profile produced by their new Linac is within 1% of that produced by the emulated 10 MV spectrum for all depths greater than 1.5 cm. The penumbra produced is 11% narrower, as measured from 80% to 20% of the central axis dose. Conclusions: The authors have successfully designed and simulated an S-band waveguide of length of 27.5 cm capable of producing a 10 MV photon beam. This waveguide operates well within the breakdown threshold determined for the cavity geometry used. The designed Linac produces depth dose profiles similar to those of the emulated 10 MV Linac (waveguide-length of 1.5 m) but yields a narrower penumbra.« less

Sub-bandage sensing system for remote monitoring of chronic wounds in healthcare

NASA Astrophysics Data System (ADS)

Hariz, Alex; Mehmood, Nasir; Voelcker, Nico

2015-12-01

Chronic wounds, such as venous leg ulcers, can be monitored non-invasively by using modern sensing devices and wireless technologies. The development of such wireless diagnostic tools may improve chronic wound management by providing evidence on efficacy of treatments being provided. In this paper we present a low-power portable telemetric system for wound condition sensing and monitoring. The system aims at measuring and transmitting real-time information of wound-site temperature, sub-bandage pressure and moisture level from within the wound dressing. The system comprises commercially available non-invasive temperature, moisture, and pressure sensors, which are interfaced with a telemetry device on a flexible 0.15 mm thick printed circuit material, making up a lightweight biocompatible sensing device. The real-time data obtained is transmitted wirelessly to a portable receiver which displays the measured values. The performance of the whole telemetric sensing system is validated on a mannequin leg using commercial compression bandages and dressings. A number of trials on a healthy human volunteer are performed where treatment conditions were emulated using various compression bandage configurations. A reliable and repeatable performance of the system is achieved under compression bandage and with minimal discomfort to the volunteer. The system is capable of reporting instantaneous changes in bandage pressure, moisture level and local temperature at wound site with average measurement resolutions of 0.5 mmHg, 3.0 %RH, and 0.2 °C respectively. Effective range of data transmission is 4-5 m in an open environment.

Development of decellularized aortic valvular conduit coated by heparin-SDF-1α multilayer.

PubMed

Zhou, Jingxin; Ye, Xiaofeng; Wang, Zhe; Liu, Jun; Zhang, Busheng; Qiu, Jiapei; Sun, Yanjun; Li, Haiqing; Zhao, Qiang

2015-02-01

Decellularization can reduce the immune response to aortic valve allograft tissue, but the thrombogenicity and in vivo remolding of these grafts remain controversial. The aim of the present study was to modify the surface of decellularized valvular conduits with heparin-stromal cell-derived factor-1α (SDF-1α) polyelectrolyte multilayer film and to test the thrombogenicity and biocompatibility in vitro and recellularization in vivo. The donor aortic valvular conduits were decellularized with a combination of different detergents and were coated with heparin and SDF-1α alternately to form a polyelectrolyte multilayer. Platelet adhesion and lactate dehydrogenase assay were used to evaluate the antiplatelet property. The adhesion, growth, and migration of bone marrow stem cells (BMSCs) to the scaffolds were assessed. For in vivo studies, the grafts were anastomosed to the infrarenal aorta, without or with heparin and SDF-1α multilayer. Functional assessment was performed by Doppler echography and micro-computed tomography at 2-week and 4-week time points after implantation. Explanted grafts were examined histologically and by immunohistochemistry. In vitro studies demonstrated that the heparin-SDF-1α multilayer film improved hemocompatibility with respect to a substantial reduction of platelet adhesion. BMSCs also achieved better adhesion, proliferation, and migration on the modified graft. For in vivo studies, the grafts in both groups remained patent after 4 weeks, but it was demonstrated that the modified decellularized grafts had better self-endothelialization and recruitment of endothelial progenitor cells. These results indicate that heparin-SDF-1α multilayer film can be used to cover the decellularized aortic valvular graft to decrease platelet adhesion while precipitating regeneration of the decellularized aortic valve allograft in vivo. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Is CHA2DS2-VASc appropriate for hyperthyroid patients with atrial fibrillation? Implications of adding a transesophageal echocardiography evaluation.

PubMed

de Souza, Marcus Vinicius Leitão; de Fátima Dos Santos Teixeira, Patricia; Vaisman, Mario; Xavier, Sergio Salles

2017-02-01

Anticoagulation remains a controversial issue among hyperthyroid patients with atrial fibrillation (AF). We aimed to evaluate the prevalence of the thrombogenic milieu (TM), detected using transesophageal echocardiography (TEE), among patients with AF related to hyperthyroidism, and to correlate these findings with the clinical embolic risk classification (CHA 2 DS 2 -VASc). CHA 2 DS 2 -VASc score, thyroid hormonal status, time since hyperthyroidism diagnosis, transthoracic echocardiography (TTE) and TEE were assessed in 47 consecutive patients aged between 18 and 65years with AF related to hyperthyroidism. The following TEE parameters defined TM: dense spontaneous echo contrast, thrombi, or left atrial appendage (LAA) blood flow velocities <0.20m/s. Non-classic TM was defined as non-dense SEC plus LAA flow velocity 0.20-0.40m/s. Pulmonary hypertension was present in 39/47 (81.4%) and TM in 22/47 (46.8%) patients. Despite a low CHA 2 DS 2 -VASc score of 0/1, 10 of 19 (52.6%) patients had a TM, whereas 16 of 28 (57.1%) patients with score ≥2 had none. The probability of having a TM did not correlate with CHA 2 DS 2 -VASc scores. On regression binary analysis, hyperthyroidism diagnosed more than 12months previous was independently associated with non-classic TM (p=0.031). Among patients younger than 65years of age with AF related to hyperthyroidism, pulmonary hypertension and TM on TEE were highly prevalent. There was no association between CHA 2 DS 2 -VASc with TEE markers of TM. Thyroid status, especially longer duration of hyperthyroidism might influence thrombogenic abnormalities. TEE adds useful information that may change antithrombotic therapy if otherwise guided solely by clinical risk classification. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Intake of phenol-rich virgin olive oil improves the postprandial prothrombotic profile in hypercholesterolemic patients.

PubMed

Ruano, Juan; López-Miranda, José; de la Torre, Rafael; Delgado-Lista, Javier; Fernández, Javier; Caballero, Javier; Covas, María Isabel; Jiménez, Yolanda; Pérez-Martínez, Pablo; Marín, Carmen; Fuentes, Francisco; Pérez-Jiménez, Francisco

2007-08-01

Oxidative stress associated with postprandial lipemia contributes to endothelial dysfunction, which shifts hemostasis to a more thrombogenic state. We investigated whether a high concentration of phenols in olive oil can partly reverse this phenomenon. Twenty-one hypercholesterolemic volunteers received 2 breakfasts rich in olive oils with different phenolic contents (80 or 400 ppm) according to a randomized, sequential crossover design. Plasma concentrations of lipid fractions, factor VII antigen (FVIIag), activated factor VII (FVIIa), and plasminogen activator inhibitor-1 (PAI-1) activity were measured at baseline and postprandially. Concentrations of FVIIa increased less (P = 0.018) and plasma PAI-1 activity decreased more (P = 0.021) 2 h after the high-phenol meal than after the low-phenol meal. FVIIa concentrations 120 min after intake of the olive oil with a high phenol content correlated positively with fasting plasma triacylglycerols (P = 0.001), area under the curve (AUC) of triacylglycerols (P = 0.001), and AUC of nonesterified fatty acids (P = 0.024) and negatively with hydroxytyrosol plasma concentrations at 60 min (P = 0.039) and fasting HDL-cholesterol concentrations (P = 0.005). PAI-1 positively correlated with homeostasis model assessment of insulin resistance (P = 0.005) and fasting triacylglycerols (P = 0.025) and inversely with adiponectin (P = 0.026). In a multivariate analysis, the AUCs of nonesterified fatty acids (R(2) = 0.467; beta: 0.787; SE: 0.02; P < 0.001) and adiponectin (R(2) = 0.232; beta: -1.594; SE: 0.629; P < 0.05) were the strongest predictors of plasma FVIIa and PAI-1, respectively. A virgin olive oil with a high content of phenolic compounds changes the postprandial hemostatic profile to a less thrombogenic state.

The effect of heparin rinse on the biocompatibility of continuous veno-venous hemodiafiltration.

PubMed

Opatrný, K; Polanská, K; Krouzecký, A; Vít, L; Novák, I; Kasal, E

2002-06-01

The aims of our cross-over randomized study were (1) to assess hemostasis in patients with acute renal failure (ARF) and (2) to determine whether or not the generally recommended heparin rinse of the extracorporeal circuit (ECC) prior to the procedure affects thrombogenicity, complement activation, and leukocyte count in blood during continuous venovenous hemodiafiltration (CVVHDF). Eleven critically ill ARF patients were treated, in random order, using CVVHDF in postdilution setup following ECC rinse with saline (A) with heparin at a concentration of 2,000 IU/L (10 procedures), (B) with heparin at a concentration of 10,000 IU/L (7 procedures), and (C) without heparin (9 procedures). Except for the rinse, anticoagulation therapy did not differ in individual patients during the procedures. Blood was withdrawn before, and at minutes 15, 60, and 360 invariably at diafilter inlet and outlet. Compared with healthy individuals, patients showed lower blood thrombocyte counts (153 vs 233*10(9)/L, p<0.01, arithmetic means, Student's t test), longer aPTT (44 vs 36 s, p<0.05), higher plasma levels of heparin (0.1 vs 0.0 U/mL, p<0.05), D-dimer (1129 vs 36 ng/mL, p<0.001) and beta-thromboglobulin (BTG) (159 vs 37 U/mL, p<0.001) prior to CVVHDF. The comparison of procedures with different rinsing technique did not reveal any significant difference in their effects on blood thrombocyte and leukocyte counts, aPTT, plasma levels of heparin, BTG, thrombin-antithrombin III complexes, D-dimer, or the C5a complement component. (1) Patients indicated for CVVHDF show impaired hemostasis involving thrombocytes, coagulation, and fibrinolysis, (2) no beneficial effect of heparin rinse on CVVHDF ECC thrombogenicity, complement activation or blood leukocyte counts was demonstrated.

Reduction of Late In-Stent Stenosis in a Porcine Coronary Artery Model by Cobalt Chromium Stents with a Nanocoat of Polyphosphazene (Polyzene-F)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stampfl, Ulrike; Sommer, Christof-Matthias; Thierjung, Heidi

2008-11-15

The purpose of this study was to investigate the potential of nanoscale coating with the highly biocompatible polymer Polyzene-F (PZF), in combination with cobalt chromium and stainless steel stents, to reduce in-stent stenosis, thrombogenicity, and vessel wall injury and inflammation. One bare cobalt chromium, PZF-nanocoated stainless steel or PZF-nanocoated cobalt chromium stent was implanted in right coronary artery of 30 mini-pigs (4- or 12-week follow-up). Primary study end points were in-stent stenosis and thrombogenicity. Secondary study end points were vessel wall injury and inflammation as evaluated by microscopy and a new immunoreactivity score applying C-reactive protein (CRP), tumor-necrosis factor alphamore » (TNF{alpha}), and TGF{beta}. At 12 weeks, angiography showed a significantly lower average loss in lumen diameter (2.1% {+-} 3.05%) in PZF-nanocoated cobalt chromium stents compared with stents in the other groups (9.73% {+-} 4.93% for bare cobalt chromium stents and 9.71% {+-} 7% for PZF-nanocoated stainless steel stents; p = 0.04), which was confirmed at microscopy (neointima 40.7 {+-} 16 {mu}m in PZF-nanocoated cobalt chromium stents, 74.7 {+-} 57.6 {mu}m in bare cobalt chromium stents, and 141.5 {+-} 109 {mu}m in PZF-nanocoated stainless steel stents; p = 0.04). Injury and inflammation scores were low in all stents and were without significant differences. PZF-nanocoated cobalt chromium stents provided the highest efficacy in reducing in-stent stenosis at long-term follow-up. The PZF nanocoat proved to be biocompatible with respect to thromboresistance and inflammation. Our data suggest that its combination with cobalt chromium stents might provide an interesting passive stent platform.« less

Fabrication and In vivo Thrombogenicity Testing of Nitric Oxide Generating Artificial Lungs

PubMed Central

Amoako, Kagya A; Montoya, Patrick J; Major, Terry C; Suhaib, Ahmed B; Handa, Hitesh; Brant, David O; Meyerhoff, Mark E; Bartlett, Robert H; Cook, Keith E

2013-01-01

Hollow fiber artificial lungs are increasingly being used for long-term applications. However, clot formation limits their use to 1-2 weeks. This study investigated the effect of nitric oxide generating (NOgen) hollow fibers on artificial lung thrombogenicity. Silicone hollow fibers were fabricated to incorporate 50 nm copper particles as a catalyst for NO generation from the blood. Fibers with and without (control) these particles were incorporated into artificial lungs with a 0.1 m2 surface area and inserted in circuits coated tip-to-tip with the NOgen material. Circuits (N=5/each) were attached to rabbits in a pumpless, arterio-venous configuration and run for 4 hrs at an activated clotting time of 350-400s. Three control circuits clotted completely, while none of the NOgen circuits failed. Accordingly, blood flows were significantly higher in the NOgen group (95.9 ± 11.7, p < 0.01) compared to the controls (35.2 ± 19.7) (ml/min), and resistance was significantly higher in the control group after 4 hours (15.38 ± 9.65, p<0.001) than in NOgen (0.09 ± 0.03) (mmHg/mL/min). On the other hand, platelet counts and plasma fibrinogen concentration expressed as percent of baseline in control group (63.7 ± 5.7%, 77.2 ± 5.6% [p<0.05]) were greater than those in the NOgen group (60.4 ± 5.1%, 63.2 ± 3.7%). Plasma copper levels in the NOgen group were 2.8 times baseline at 4 hours (132.8 ± 4.5 μg/dl) and unchanged in the controls. This work demonstrates that NO generating gas exchange fibers could be a potentially effective way to control coagulation inside artificial lungs. PMID:23613156

Hemocompatibility Comparison of Biomedical Grade Polymers Using Rabbit Thrombogenicity Model for Preparing Nonthrombogenic Nitric Oxide Releasing Surfaces

PubMed Central

Handa, Hitesh; Major, Terry C.; Brisbois, Elizabeth J.; Amoako, Kagya A.; Meyerhoff, Mark E.; Bartlett, Robert H.

2014-01-01

Nitric oxide (NO) is an endogenous vasodilator as well as natural inhibitor of platelet adhesion/activation. Nitric oxide releasing (NOrel) materials can be prepared by doping an NO donor species, such as diazeniumdiolated dibutylhexanediamine (DBHD/N2O2), within a polymer coating. The inherent hemocompatibility properties of the base polymer can also influence the efficiency of such NO release coatings. In this study, four biomedical grade polymers were evaluated in a 4 h rabbit model of thrombogenicity for their effects on extracorporeal circuit thrombus formation and circulating platelet count. At the end of 4 h, Elast-Eon E2As was found to preserve 58% of baseline platelets versus 48, 40, and 47% for PVC/DOS, Tecophilic SP-60D-60, and Tecoflex SG80A, respectively. Elast-Eon also had significantly lower clot area of 5.2 cm2 compared to 6.7, 6.1, and 6.9 cm2 for PVC/DOS, SP-60D-60, and SG80A, respectively. Based on the results obtained for the base polymer comparison study, DBHD/N2O2-doped E2As was evaluated in short-term (4 h) rabbit studies to observe the NO effects on prevention of clotting and preservation of platelet function. Platelet preservation for this optimal NO release formulation was 97% of baseline after 4 h, and clot area was 0.9 cm2 compared to 5.2 cm2 for controls, demonstrating that combining E2As with NO release provides a truly advanced hemocompatible polymer coating for extracorporeal circuits and potentially other blood contacting applications. PMID:24634777

Fast neural network surrogates for very high dimensional physics-based models in computational oceanography.

PubMed

van der Merwe, Rudolph; Leen, Todd K; Lu, Zhengdong; Frolov, Sergey; Baptista, Antonio M

2007-05-01

We present neural network surrogates that provide extremely fast and accurate emulation of a large-scale circulation model for the coupled Columbia River, its estuary and near ocean regions. The circulation model has O(10(7)) degrees of freedom, is highly nonlinear and is driven by ocean, atmospheric and river influences at its boundaries. The surrogates provide accurate emulation of the full circulation code and run over 1000 times faster. Such fast dynamic surrogates will enable significant advances in ensemble forecasts in oceanography and weather.

Model description document for a computer program for the emulation/simulation of a space station environmental control and life support system (ESCM)

NASA Technical Reports Server (NTRS)

Yanosy, James L.

1988-01-01

Emulation/Simulation Computer Model (ESCM) computes the transient performance of a Space Station air revitalization subsystem with carbon dioxide removal provided by a solid amine water desorbed subsystem called SAWD. This manual describes the mathematical modeling and equations used in the ESCM. For the system as a whole and for each individual component, the fundamental physical and chemical laws which govern their operations are presented. Assumptions are stated, and when necessary, data is presented to support empirically developed relationships.

Specifying a target trial prevents immortal time bias and other self-inflicted injuries in observational analyses

PubMed Central

Hernán, Miguel A.; Sauer, Brian C.; Hernández-Díaz, Sonia; Platt, Robert; Shrier, Ian

2016-01-01

Many analyses of observational data are attempts to emulate a target trial. The emulation of the target trial may fail when researchers deviate from simple principles that guide the design and analysis of randomized experiments. We review a framework to describe and prevent biases, including immortal time bias, that result from a failure to align start of follow-up, specification of eligibility, and treatment assignment. We review some analytic approaches to avoid these problems in comparative effectiveness or safety research. PMID:27237061

Research on two-port network of wavelet transform processor using surface acoustic wavelet devices and its application.

PubMed

Liu, Shoubing; Lu, Wenke; Zhu, Changchun

2017-11-01

The goal of this research is to study two-port network of wavelet transform processor (WTP) using surface acoustic wave (SAW) devices and its application. The motive was prompted by the inconvenience of the long research and design cycle and the huge research funding involved with traditional method in this field, which were caused by the lack of the simulation and emulation method of WTP using SAW devices. For this reason, we introduce the two-port network analysis tool, which has been widely used in the design and analysis of SAW devices with uniform interdigital transducers (IDTs). Because the admittance parameters calculation formula of the two-port network can only be used for the SAW devices with uniform IDTs, this analysis tool cannot be directly applied into the design and analysis of the processor using SAW devices, whose input interdigital transducer (IDT) is apodized weighting. Therefore, in this paper, we propose the channel segmentation method, which can convert the WTP using SAW devices into parallel channels, and also provide with the calculation formula of the number of channels, the number of finger pairs and the static capacitance of an interdigital period in each parallel channel firstly. From the parameters given above, we can calculate the admittance parameters of the two port network for each channel, so that we can obtain the admittance parameter of the two-port network of the WTP using SAW devices on the basis of the simplification rule of parallel two-port network. Through this analysis tool, not only can we get the impulse response function of the WTP using SAW devices but we can also get the matching circuit of it. Large numbers of studies show that the parameters of the two-port network obtained by this paper are consistent with those measured by network analyzer E5061A, and the impulse response function obtained by the two-port network analysis tool is also consistent with that measured by network analyzer E5061A, which can meet the accuracy requirements of the analysis of the WTP using SAW devices. Therefore the two-port network analysis tool discussed in this paper has comparatively higher theoretical and practical value. Copyright © 2017 Elsevier B.V. All rights reserved.

Robotic End Effectors for Hard-Rock Climbing

NASA Technical Reports Server (NTRS)

Kennedy, Brett; Leger, Patrick

2004-01-01

Special-purpose robot hands (end effectors) now under development are intended to enable robots to traverse cliffs much as human climbers do. Potential applications for robots having this capability include scientific exploration (both on Earth and other rocky bodies in space), military reconnaissance, and outdoor search and rescue operations. Until now, enabling robots to traverse cliffs has been considered too difficult a task because of the perceived need of prohibitively sophisticated planning algorithms as well as end effectors as dexterous as human hands. The present end effectors are being designed to enable robots to attach themselves to typical rock-face features with less planning and simpler end effectors. This advance is based on the emulation of the equipment used by human climbers rather than the emulation of the human hand. Climbing-aid equipment, specifically cams, aid hooks, and cam hooks, are used by sport climbers when a quick ascent of a cliff is desired (see Figure 1). Currently two different end-effector designs have been created. The first, denoted the simple hook emulator, consists of three "fingers" arranged around a central "palm." Each finger emulates the function of a particular type of climbing hook (aid hook, wide cam hook, and a narrow cam hook). These fingers are connected to the palm via a mechanical linkage actuated with a leadscrew/nut. This mechanism allows the fingers to be extended or retracted. The second design, denoted the advanced hook emulator (see Figure 2), shares these features, but it incorporates an aid hook and a cam hook into each finger. The spring-loading of the aid hook allows the passive selection of the type of hook used. The end effectors can be used in several different modes. In the aid-hook mode, the aid hook on one of the fingers locks onto a horizontal ledge while the other two fingers act to stabilize the end effector against the cliff face. In the cam-hook mode, the broad, flat tip of the cam hook is inserted into a non-horizontal crack in the cliff face. A subsequent transfer of weight onto the end effector causes the tip to rotate within the crack, creating a passive, self-locking action of the hook relative to the crack. In the advanced hook emulator, the aid hook is pushed into its retracted position by contact with the cliff face as the cam hook tip is inserted into the crack. When a cliff face contains relatively large pockets or cracks, another type of passive self-locking can be used. Emulating the function of the piece of climbing equipment called a "cam" (note: not the same as a "cam hook"; see Figure 1), the fingers can be fully retracted and the entire end effector inserted into the feature. The fingers are then extended as far as the feature allows. Any weight then transferred to the end effector will tend to extend the fingers further due to frictional force, passively increasing the grip on the feature. In addition to the climbing modes, these end effectors can be used to walk on (either on the palm or the fingertips) and to grasp objects by fully extending the fingers.

Cross-standard user description in mobile, medical oriented virtual collaborative environments

NASA Astrophysics Data System (ADS)

Ganji, Rama Rao; Mitrea, Mihai; Joveski, Bojan; Chammem, Afef

2015-03-01

By combining four different open standards belonging to the ISO/IEC JTC1/SC29 WG11 (a.k.a. MPEG) and W3C, this paper advances an architecture for mobile, medical oriented virtual collaborative environments. The various users are represented according to MPEG-UD (MPEG User Description) while the security issues are dealt with by deploying the WebID principles. On the server side, irrespective of their elementary types (text, image, video, 3D, …), the medical data are aggregated into hierarchical, interactive multimedia scenes which are alternatively represented into MPEG-4 BiFS or HTML5 standards. This way, each type of content can be optimally encoded according to its particular constraints (semantic, medical practice, network conditions, etc.). The mobile device should ensure only the displaying of the content (inside an MPEG player or an HTML5 browser) and the capturing of the user interaction. The overall architecture is implemented and tested under the framework of the MEDUSA European project, in partnership with medical institutions. The testbed considers a server emulated by a PC and heterogeneous user devices (tablets, smartphones, laptops) running under iOS, Android and Windows operating systems. The connection between the users and the server is alternatively ensured by WiFi and 3G/4G networks.

Evaluation of bluetooth low power for physiological monitoring in a home based cardiac rehabilitation program.

PubMed

Martin, Timothy; Ding, Hang; D'Souza, Matthew; Karunanithi, Mohan

2012-01-01

Cardiovascular disease (CVD) is the leading cause of mortality in Australia, and places large burdens on the healthcare system. To assist patients with CVDs in recovering from cardiac events and mediating cardiac risk factors, a home based cardiac rehabilitation program, known as the Care Assessment Platform (CAP), was developed. In the CAP program, patients are required to manually enter health information into their mobile phones on a daily basis. The manual operation is often subject to human errors and is inconvenient for some elderly patients. To improve this, an automated wireless solution has been desired. The objectives of this paper are to investigate the feasibility of implementing the newly released Bluetooth 4.0 (BT4.0) for the CAP program, and practically evaluate BT4.0 communications between a developed mobile application and some emulated healthcare devices. The study demonstrated that BT4.0 addresses usability, interoperability and security for healthcare applications, reduces the power consumption in wireless communication, and improves the flexibility of interface for software development. This evaluation study provides an essential mobile BT4.0 framework to incorporate a large range of healthcare devices for clinical assessment and intervention in the CAP program, and hence it is useful for similar development and research work of other mobile healthcare solutions.

Control devices and steering strategies in pathway surgery.

PubMed

Fan, Chunman; Jelínek, Filip; Dodou, Dimitra; Breedveld, Paul

2015-02-01

For pathway surgery, that is, minimally invasive procedures carried out transluminally or through instrument-created pathways, handheld maneuverable instruments are being developed. As the accompanying control interfaces of such instruments have not been optimized for intuitive manipulation, we investigated the effect of control mode (1DoF or 2DoF), and control device (joystick or handgrip) on human performance in a navigation task. The experiments were conducted using the Endo-PaC (Endoscopic-Path Controller), a simulator that emulates the shaft and handle of a maneuverable instrument, combined with custom-developed software animating pathway surgical scenarios. Participants were asked to guide a virtual instrument without collisions toward a target located at the end of a virtual curved tunnel. The performance was assessed in terms of task completion time, path length traveled by the virtual instrument, motion smoothness, collision metrics, subjective workload, and personal preference. The results indicate that 2DoF control leads to faster task completion and fewer collisions with the tunnel wall combined with a strong subjective preference compared with 1DoF control. Handgrip control appeared to be more intuitive to master than joystick control. However, the participants experienced greater physical demand and had longer path lengths with handgrip than joystick control. Copyright © 2015 Elsevier Inc. All rights reserved.

Using partial reconfiguration for SoC design and implementation

NASA Astrophysics Data System (ADS)

Krasteva, Yana E.; Portilla, Jorge; Tobajas Guerrero, Félix; de la Torre, Eduardo

2009-05-01

Most reconfigurable systems rely on FPGA technology. Among these ones, those which permit dynamic and partial reconfiguration, offer added benefits in flexibility, in-field device upgrade, improved design and manufacturing time, and even, in some cases, power consumption reductions. However, dynamic reconfiguration is a complex task, and the real benefits of its use in real applications have been often questioned. This paper presents an overview of the partial reconfiguration technique application, along with four original applications. The main goal of these applications is to test several architectures with different flexibility and, to search for the partial reconfiguration "killing application", that is, the application that better demonstrates the benefits of today reconfigurable systems based on commercial FPGAs. Therefore, the presented applications are rather a proof of concept, than fully operative and closed systems. First, a brief introduction to the partial reconfigurable systems application topic has been included. After that, the descriptions of the created reconfigurable systems are presented: first, an on-chip communications emulation framework, second, an on chip debugging system, third, a wireless sensor network reconfigurable node and finally, a remote reconfigurable client-server device. Each application is described in a separate section of the paper along with some test and results. General conclusions are included at the end of the paper.

Multi-level emulation of a volcanic ash transport and dispersion model to quantify sensitivity to uncertain parameters

NASA Astrophysics Data System (ADS)

Harvey, Natalie J.; Huntley, Nathan; Dacre, Helen F.; Goldstein, Michael; Thomson, David; Webster, Helen

2018-01-01

Following the disruption to European airspace caused by the eruption of Eyjafjallajökull in 2010 there has been a move towards producing quantitative predictions of volcanic ash concentration using volcanic ash transport and dispersion simulators. However, there is no formal framework for determining the uncertainties of these predictions and performing many simulations using these complex models is computationally expensive. In this paper a Bayesian linear emulation approach is applied to the Numerical Atmospheric-dispersion Modelling Environment (NAME) to better understand the influence of source and internal model parameters on the simulator output. Emulation is a statistical method for predicting the output of a computer simulator at new parameter choices without actually running the simulator. A multi-level emulation approach is applied using two configurations of NAME with different numbers of model particles. Information from many evaluations of the computationally faster configuration is combined with results from relatively few evaluations of the slower, more accurate, configuration. This approach is effective when it is not possible to run the accurate simulator many times and when there is also little prior knowledge about the influence of parameters. The approach is applied to the mean ash column loading in 75 geographical regions on 14 May 2010. Through this analysis it has been found that the parameters that contribute the most to the output uncertainty are initial plume rise height, mass eruption rate, free tropospheric turbulence levels and precipitation threshold for wet deposition. This information can be used to inform future model development and observational campaigns and routine monitoring. The analysis presented here suggests the need for further observational and theoretical research into parameterisation of atmospheric turbulence. Furthermore it can also be used to inform the most important parameter perturbations for a small operational ensemble of simulations. The use of an emulator also identifies the input and internal parameters that do not contribute significantly to simulator uncertainty. Finally, the analysis highlights that the faster, less accurate, configuration of NAME can, on its own, provide useful information for the problem of predicting average column load over large areas.

Amide-adducts in atherosclerosis.

PubMed

Naito, Michitaka

2014-01-01

Too many hypotheses in the etiology of atherosclerosis have been proposed. Classically, lipid insudation hypothesis by Virchow and thrombogenic hypothesis by Rokitansky are famous. However, in the recent progress in the area of atherosclerosis, the response-to-injury hypothesis by Ross (Ross R Glomset JA, N Engl J Med 295:369-377, 420-425, 1976; Ross R, Arteriosclerosis 1:293-311, 1981; Ross R, N Engl J Med 314:488-500, 1986; Ross R, Nature 362:801-809, 1993; Ross R, N Engl J Med 340:115-126, 1999) has been the leading one. In this review, however, the author focuses to the recent debate on the role of oxidative modification of atherogenic lipoproteins.

Evaluating the accuracy of climate change pattern emulation for low warming targets

NASA Astrophysics Data System (ADS)

Tebaldi, Claudia; Knutti, Reto

2018-05-01

Global climate policy is increasingly debating the value of very low warming targets, yet not many experiments conducted with global climate models in their fully coupled versions are currently available to help inform studies of the corresponding impacts. This raises the question whether a map of warming or precipitation change in a world 1.5 °C warmer than preindustrial can be emulated from existing simulations that reach higher warming targets, or whether entirely new simulations are required. Here we show that also for this type of low warming in strong mitigation scenarios, climate change signals are quite linear as a function of global temperature. Therefore, emulation techniques amounting to linear rescaling on the basis of global temperature change ratios (like simple pattern scaling) provide a viable way forward. The errors introduced are small relative to the spread in the forced response to a given scenario that we can assess from a multi-model ensemble. They are also small relative to the noise introduced into the estimates of the forced response by internal variability within a single model, which we can assess from either control simulations or initial condition ensembles. Challenges arise when scaling inadvertently reduces the inter-model spread or suppresses the internal variability, both important sources of uncertainty for impact assessment, or when the scenarios have very different characteristics in the composition of the forcings. Taking advantage of an available suite of coupled model simulations under low-warming and intermediate scenarios, we evaluate the accuracy of these emulation techniques and show that they are unlikely to represent a substantial contribution to the total uncertainty.

A Phase-Locked Loop Epilepsy Network Emulator

PubMed Central

Watson, P.D.; Horecka, K. M.; Cohen, N.J.; Ratnam, R.

2015-01-01

Most seizure forecasting employs statistical learning techniques that lack a representation of the network interactions that give rise to seizures. We present an epilepsy network emulator (ENE) that uses a network of interconnected phase-locked loops (PLLs) to model synchronous, circuit-level oscillations between electrocorticography (ECoG) electrodes. Using ECoG data from a canine-epilepsy model (Davis et al. 2011) and a physiological entropy measure (approximate entropy or ApEn, Pincus 1995), we demonstrate the entropy of the emulator phases increases dramatically during ictal periods across all ECoG recording sites and across all animals in the sample. Further, this increase precedes the observable voltage spikes that characterize seizure activity in the ECoG data. These results suggest that the ENE is sensitive to phase-domain information in the neural circuits measured by ECoG and that an increase in the entropy of this measure coincides with increasing likelihood of seizure activity. Understanding this unpredictable phase-domain electrical activity present in ECoG recordings may provide a target for seizure detection and feedback control. PMID:26664133

Emulation Platform for Cyber Analysis of Wireless Communication Network Protocols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Leeuwen, Brian P.; Eldridge, John M.

Wireless networking and mobile communications is increasing around the world and in all sectors of our lives. With increasing use, the density and complexity of the systems increase with more base stations and advanced protocols to enable higher data throughputs. The security of data transported over wireless networks must also evolve with the advances in technologies enabling more capable wireless networks. However, means for analysis of the effectiveness of security approaches and implementations used on wireless networks are lacking. More specifically a capability to analyze the lower-layer protocols (i.e., Link and Physical layers) is a major challenge. An analysis approachmore » that incorporates protocol implementations without the need for RF emissions is necessary. In this research paper several emulation tools and custom extensions that enable an analysis platform to perform cyber security analysis of lower layer wireless networks is presented. A use case of a published exploit in the 802.11 (i.e., WiFi) protocol family is provided to demonstrate the effectiveness of the described emulation platform.« less

A satellite orbital testbed for SATCOM using mobile robots

NASA Astrophysics Data System (ADS)

Shen, Dan; Lu, Wenjie; Wang, Zhonghai; Jia, Bin; Wang, Gang; Wang, Tao; Chen, Genshe; Blasch, Erik; Pham, Khanh

2016-05-01

This paper develops and evaluates a satellite orbital testbed (SOT) for satellite communications (SATCOM). SOT can emulate the 3D satellite orbit using the omni-wheeled robots and a robotic arm. The 3D motion of satellite is partitioned into the movements in the equatorial plane and the up-down motions in the vertical plane. The former actions are emulated by omni-wheeled robots while the up-down motions are performed by a stepped-motor-controlled-ball along a rod (robotic arm), which is attached to the robot. The emulated satellite positions will go to the measure model, whose results will be used to perform multiple space object tracking. Then the tracking results will go to the maneuver detection and collision alert. The satellite maneuver commands will be translated to robots commands and robotic arm commands. In SATCOM, the effects of jamming depend on the range and angles of the positions of satellite transponder relative to the jamming satellite. We extend the SOT to include USRP transceivers. In the extended SOT, the relative ranges and angles are implemented using omni-wheeled robots and robotic arms.

Using Big Data to Emulate a Target Trial When a Randomized Trial Is Not Available.

PubMed

Hernán, Miguel A; Robins, James M

2016-04-15

Ideally, questions about comparative effectiveness or safety would be answered using an appropriately designed and conducted randomized experiment. When we cannot conduct a randomized experiment, we analyze observational data. Causal inference from large observational databases (big data) can be viewed as an attempt to emulate a randomized experiment-the target experiment or target trial-that would answer the question of interest. When the goal is to guide decisions among several strategies, causal analyses of observational data need to be evaluated with respect to how well they emulate a particular target trial. We outline a framework for comparative effectiveness research using big data that makes the target trial explicit. This framework channels counterfactual theory for comparing the effects of sustained treatment strategies, organizes analytic approaches, provides a structured process for the criticism of observational studies, and helps avoid common methodologic pitfalls. © The Author 2016. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Brain-Inspired Photonic Signal Processor for Generating Periodic Patterns and Emulating Chaotic Systems

NASA Astrophysics Data System (ADS)

Antonik, Piotr; Haelterman, Marc; Massar, Serge

2017-05-01

Reservoir computing is a bioinspired computing paradigm for processing time-dependent signals. Its hardware implementations have received much attention because of their simplicity and remarkable performance on a series of benchmark tasks. In previous experiments, the output was uncoupled from the system and, in most cases, simply computed off-line on a postprocessing computer. However, numerical investigations have shown that feeding the output back into the reservoir opens the possibility of long-horizon time-series forecasting. Here, we present a photonic reservoir computer with output feedback, and we demonstrate its capacity to generate periodic time series and to emulate chaotic systems. We study in detail the effect of experimental noise on system performance. In the case of chaotic systems, we introduce several metrics, based on standard signal-processing techniques, to evaluate the quality of the emulation. Our work significantly enlarges the range of tasks that can be solved by hardware reservoir computers and, therefore, the range of applications they could potentially tackle. It also raises interesting questions in nonlinear dynamics and chaos theory.

The introspective may achieve more: Enhancing existing Geoscientific models with native-language emulated structural reflection

NASA Astrophysics Data System (ADS)

Ji, Xinye; Shen, Chaopeng

2018-01-01

Geoscientific models manage myriad and increasingly complex data structures as trans-disciplinary models are integrated. They often incur significant redundancy with cross-cutting tasks. Reflection, the ability of a program to inspect and modify its structure and behavior at runtime, is known as a powerful tool to improve code reusability, abstraction, and separation of concerns. Reflection is rarely adopted in high-performance Geoscientific models, especially with Fortran, where it was previously deemed implausible. Practical constraints of language and legacy often limit us to feather-weight, native-language solutions. We demonstrate the usefulness of a structural-reflection-emulating, dynamically-linked metaObjects, gd. We show real-world examples including data structure self-assembly, effortless input/output (IO) and upgrade to parallel I/O, recursive actions and batch operations. We share gd and a derived module that reproduces MATLAB-like structure in Fortran and C++. We suggest that both a gd representation and a Fortran-native representation are maintained to access the data, each for separate purposes. Embracing emulated reflection allows generically-written codes that are highly re-usable across projects.

Evolution of cooperative behavior in simulation agents

NASA Astrophysics Data System (ADS)

Stroud, Phillip D.

1998-03-01

A simulated automobile factory paint shop is used as a testbed for exploring the emulation of human decision-making behavior. A discrete-events simulation of the paint shop as a collection of interacting Java actors is described. An evolutionary cognitive architecture is under development for building software actors to emulate humans in simulations of human- dominated complex systems. In this paper, the cognitive architecture is extended by implementing a persistent population of trial behaviors with an incremental fitness valuation update strategy, and by allowing a group of cognitive actors to share information. A proof-of-principle demonstration is presented.

Integration Testing of Space Flight Systems

NASA Technical Reports Server (NTRS)

Honeycutt, Timothy; Sowards, Stephanie

2008-01-01

Based on the previous success' of Multi-Element Integration Testing (MEITs) for the International Space Station Program, these type of integrated tests have also been planned for the Constellation Program: MEIT (1) CEV to ISS (emulated) (2) CEV to Lunar Lander/EDS (emulated) (3) Future: Lunar Surface Systems and Mars Missions Finite Element Integration Test (FEIT) (1) CEV/CLV (2) Lunar Lander/EDS/CaL V Integrated Verification Tests (IVT) (1) Performed as a subset of the FEITs during the flight tests and then performed for every flight after Full Operational Capability (FOC) has been obtained with the flight and ground Systems.

Specifying a target trial prevents immortal time bias and other self-inflicted injuries in observational analyses.

PubMed

Hernán, Miguel A; Sauer, Brian C; Hernández-Díaz, Sonia; Platt, Robert; Shrier, Ian

2016-11-01

Many analyses of observational data are attempts to emulate a target trial. The emulation of the target trial may fail when researchers deviate from simple principles that guide the design and analysis of randomized experiments. We review a framework to describe and prevent biases, including immortal time bias, that result from a failure to align start of follow-up, specification of eligibility, and treatment assignment. We review some analytic approaches to avoid these problems in comparative effectiveness or safety research. Copyright © 2016 Elsevier Inc. All rights reserved.

MCCx C3I Control Center Interface Emulator

NASA Technical Reports Server (NTRS)

Mireles, James R.

2010-01-01

This slide presentation reviews the project to develop and demonstrate alternate Information Technologies and systems for new Mission Control Centers that will reduce the cost of facility development, maintenance and operational costs and will enable more efficient cost and effective operations concepts for ground support operations. The development of a emulator for the Control Center capability will enable the facilities to conduct the simulation requiring interactivity with the Control Center when it is off line or unavailable, and it will support testing of C3I interfaces for both command and telemetry data exchange messages (DEMs).

Guidance, Navigation and Control Digital Emulation Technology Laboratory. Volume 1. Part 3. Task 1: Digital Emulation Technology Laboratory

DTIC Science & Technology

1991-09-27

ISTT IEXIT IGO MAGV TGII ROLLERI YAWER LA !10 TRMTGO TGE 1 TGE2ALI IBURNI ACQD UVs MVS CMMD VCMD IFTAB TFTAB ACSLEV DTOFFV IVTAB TB URNM TI MONVI TVTAB...Volume 1, Part 3 C b inertdfatal loup ndxjust compu ed . Missile states must not CI C transition has occurred since the last C C integration step . The...SUBROUTINE RESP2R ( DT,WD,ZD,CILL,CIL,CI., COLL ,COL,CO) C C SUBROUTINE NAME : RESP2R C C AUTHOR(S) :D. F. SMITH C C FUNCTION Given a second

Effects of direct current electric fields on lung cancer cell electrotaxis in a PMMA-based microfluidic device.

PubMed

Li, Yaping; Xu, Tao; Chen, Xiaomei; Lin, Shin; Cho, Michael; Sun, Dong; Yang, Mengsu

2017-03-01

Tumor metastasis is the primary cause of cancer death. Numerous studies have demonstrated the electrotactic responses of various cancer cell types, and suggested its potential implications in metastasis. In this study, we used a microfluidic device to emulate endogenous direct current electric field (dcEF) environment, and studied the electrotactic migration of non-small cell lung cancer cell lines (H460, HCC827, H1299, and H1975) and the underlying mechanisms. These cell lines exhibited greatly different response in applied dcEFs (2-6 V/cm). While H460 cells (large cell carcinoma) showed slight migration toward cathode, H1299 cells (large cell carcinoma) showed increased motility and dcEF-dependent anodal migration with cell reorientation. H1975 cells (adenocarcinoma) showed dcEF-dependent cathodal migration with increased motility, and HCC827 cells (adenocarcinoma) responded positively in migration speed and reorientation but minimally in migrating directions to dcEF. Activation of MAPK and PI3K signaling pathways was found to be associated with the realignment and directed migration of lung cancer cells. In addition, both Ca 2+ influx through activated stretch-activated calcium channels (SACCs) (but not voltage-gated calcium channels, VGCCs) and Ca 2+ release from intracellular storage were involved in lung cancer cell electrotactic responses. The results demonstrated that the microfluidic device provided a stable and controllable microenvironment for cell electrotaxis study, and revealed that the electrotactic responses of lung cancer cells were heterogeneous and cell-type dependent, and multiple signals contributed to lung cancer cells electrotaxis.

Combining super-ensembles and statistical emulation to improve a regional climate and vegetation model

NASA Astrophysics Data System (ADS)

Hawkins, L. R.; Rupp, D. E.; Li, S.; Sarah, S.; McNeall, D. J.; Mote, P.; Betts, R. A.; Wallom, D.

2017-12-01

Changing regional patterns of surface temperature, precipitation, and humidity may cause ecosystem-scale changes in vegetation, altering the distribution of trees, shrubs, and grasses. A changing vegetation distribution, in turn, alters the albedo, latent heat flux, and carbon exchanged with the atmosphere with resulting feedbacks onto the regional climate. However, a wide range of earth-system processes that affect the carbon, energy, and hydrologic cycles occur at sub grid scales in climate models and must be parameterized. The appropriate parameter values in such parameterizations are often poorly constrained, leading to uncertainty in predictions of how the ecosystem will respond to changes in forcing. To better understand the sensitivity of regional climate to parameter selection and to improve regional climate and vegetation simulations, we used a large perturbed physics ensemble and a suite of statistical emulators. We dynamically downscaled a super-ensemble (multiple parameter sets and multiple initial conditions) of global climate simulations using a 25-km resolution regional climate model HadRM3p with the land-surface scheme MOSES2 and dynamic vegetation module TRIFFID. We simultaneously perturbed land surface parameters relating to the exchange of carbon, water, and energy between the land surface and atmosphere in a large super-ensemble of regional climate simulations over the western US. Statistical emulation was used as a computationally cost-effective tool to explore uncertainties in interactions. Regions of parameter space that did not satisfy observational constraints were eliminated and an ensemble of parameter sets that reduce regional biases and span a range of plausible interactions among earth system processes were selected. This study demonstrated that by combining super-ensemble simulations with statistical emulation, simulations of regional climate could be improved while simultaneously accounting for a range of plausible land-atmosphere feedback strengths.

Conjunctively optimizing flash flood control and water quality in urban water reservoirs by model predictive control and dynamic emulation

NASA Astrophysics Data System (ADS)

Galelli, Stefano; Goedbloed, Albert; Schmitter, Petra; Castelletti, Andrea

2014-05-01

Urban water reservoirs are a viable adaptation option to account for increasing drinking water demand of urbanized areas as they allow storage and re-use of water that is normally lost. In addition, the direct availability of freshwater reduces pumping costs and diversifies the portfolios of drinking water supply. Yet, these benefits have an associated twofold cost. Firstly, the presence of large, impervious areas increases the hydraulic efficiency of urban catchments, with short time of concentration, increased runoff rates, losses of infiltration and baseflow, and higher risk of flash floods. Secondly, the high concentration of nutrients and sediments characterizing urban discharges is likely to cause water quality problems. In this study we propose a new control scheme combining Model Predictive Control (MPC), hydro-meteorological forecasts and dynamic model emulation to design real-time operating policies that conjunctively optimize water quantity and quality targets. The main advantage of this scheme stands in its capability of exploiting real-time hydro-meteorological forecasts, which are crucial in such fast-varying systems. In addition, the reduced computational requests of the MPC scheme allows coupling it with dynamic emulators of water quality processes. The approach is demonstrated on Marina Reservoir, a multi-purpose reservoir located in the heart of Singapore and characterized by a large, highly urbanized catchment with a short (i.e. approximately one hour) time of concentration. Results show that the MPC scheme, coupled with a water quality emulator, provides a good compromise between different operating objectives, namely flood risk reduction, drinking water supply and salinity control. Finally, the scheme is used to assess the effect of source control measures (e.g. green roofs) aimed at restoring the natural hydrological regime of Marina Reservoir catchment.

Internet Tomography in Support of Internet and Network Simulation and Emulation Modelling

NASA Astrophysics Data System (ADS)

Moloisane, A.; Ganchev, I.; O'Droma, M.

Internet performance measurement data extracted through Internet Tomography techniques and metrics and how it may be used to enhance the capacity of network simulation and emulation modelling is addressed in this paper. The advantages of network simulation and emulation as a means to aid design and develop the component networks, which make up the Internet and are fundamental to its ongoing evolution, are highlighted. The Internet's rapid growth has spurred development of new protocols and algorithms to meet changing operational requirements such as security, multicast delivery, mobile networking, policy management, and quality of service (QoS) support. Both the development and evaluation of these operational tools requires the answering of many design and operational questions. Creating the technical support required by network engineers and managers in their efforts to seek answers to these questions is in itself a major challenge. Within the Internet the number and range of services supported continues to grow exponentially, from legacy and client/server applications to VoIP, multimedia streaming services and interactive multimedia services. Services have their own distinctive requirements and idiosyncrasies. They respond differently to bandwidth limitations, latency and jitter problems. They generate different types of “conversations” between end-user terminals, back-end resources and middle-tier servers. To add to the complexity, each new or enhanced service introduced onto the network contends for available bandwidth with every other service. In an effort to ensure networking products and resources being designed and developed handling diverse conditions encountered in real Internet environments, network simulation and emulation modelling is a valuable tool, and becoming a critical element, in networking product and application design and development. The better these laboratory tools reflect real-world environment and conditions the more helpful to designers they will be.