Air cooling of disk of a solid integrally cast turbine rotor for an automotive gas turbine

NASA Technical Reports Server (NTRS)

Gladden, H. J.

1977-01-01

A thermal analysis is made of surface cooling of a solid, integrally cast turbine rotor disk for an automotive gas turbine engine. Air purge and impingement cooling schemes are considered and compared with an uncooled reference case. Substantial reductions in blade temperature are predicted with each of the cooling schemes studied. It is shown that air cooling can result in a substantial gain in the stress-rupture life of the blade. Alternatively, increases in the turbine inlet temperature are possible.

Crank case scavenging of a two-stroke-cycle engine

NASA Technical Reports Server (NTRS)

Holm, Otto

1928-01-01

Experiments with a two-stroke-cycle, crank case scavenging engine. Effect of systematic variation of the height of the scavenge and exhaust ports on the scavenging, as determined by gas analysis. The best results were obtained under conditions differing from the usual ones.

Resonant and resistive dual-mode uncooled infrared detectors toward expanded dynamic range and high linearity

NASA Astrophysics Data System (ADS)

Li, Xin; Liang, Ji; Zhang, Hongxiang; Yang, Xing; Zhang, Hao; Pang, Wei; Zhang, Menglun

2017-06-01

This paper reports an uncooled infrared (IR) detector based on a micromachined piezoelectric resonator operating in resonant and resistive dual-modes. The two sensing modes achieved IR responsivities of 2.5 Hz/nW and 900 μdB/nW, respectively. Compared with the single mode operation, the dual-mode measurement improves the limit of detection by two orders of magnitude and meanwhile maintains high linearity and responsivity in a higher IR intensity range. A combination of the two sensing modes compensates for its own shortcomings and provides a much larger dynamic range, and thus, a wider application field of the proposed detector is realized.

A Highly Efficient Six-Stroke Internal Combustion Engine Cycle with Water Injection for In-Cylinder Exhaust Heat Recovery

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

Conklin, Jim; Szybist, James P

2010-01-01

A concept is presented here that adds two additional strokes to the four-stroke Otto or Diesel cycle that has the potential to increase fuel efficiency of the basic cycle. The engine cycle can be thought of as a 4 stroke Otto or Diesel cycle followed by a 2-stroke heat recovery steam cycle. Early exhaust valve closing during the exhaust stroke coupled with water injection are employed to add an additional power stroke at the end of the conventional four-stroke Otto or Diesel cycle. An ideal thermodynamics model of the exhaust gas compression, water injection at top center, and expansion wasmore » used to investigate this modification that effectively recovers waste heat from both the engine coolant and combustion exhaust gas. Thus, this concept recovers energy from two waste heat sources of current engine designs and converts heat normally discarded to useable power and work. This concept has the potential of a substantial increase in fuel efficiency over existing conventional internal combustion engines, and under appropriate injected water conditions, increase the fuel efficiency without incurring a decrease in power density. By changing the exhaust valve closing angle during the exhaust stroke, the ideal amount of exhaust can be recompressed for the amount of water injected, thereby minimizing the work input and maximizing the mean effective pressure of the steam expansion stroke (MEPsteam). The value of this exhaust valve closing for maximum MEPsteam depends on the limiting conditions of either one bar or the dew point temperature of the expansion gas/moisture mixture when the exhaust valve opens to discard the spent gas mixture in the sixth stroke. The range of MEPsteam calculated for the geometry of a conventional gasoline spark-ignited internal combustion engine and for plausible water injection parameters is from 0.75 to 2.5 bars. Typical combustion mean effective pressures (MEPcombustion) of naturally aspirated gasoline engines are up to 10 bar, thus this concept has the potential to significantly increase the engine efficiency and fuel economy while not resulting in a decrease in power density.« less

Uncooled infrared focal plane array imaging in China

NASA Astrophysics Data System (ADS)

Lei, Shuyu

2015-06-01

This article reviews the development of uncooled infrared focal plane array (UIFPA) imaging in China in the past decade. Sensors based on optical or electrical read-out mechanism were developed but the latter dominates the market. In resistive bolometers, VOx and amorphous silicon are still the two major thermal-sensing materials. The specifications of the IRFPA made by different manufactures were collected and compared. Currently more than five Chinese companies and institutions design and fabricate uncooled infrared focal plane array. Some devices have sensitivity as high as 30 mK; the largest array for commercial products is 640×512 and the smallest pixel size is 17 μm. Emphasis is given on the pixel MEMS design, ROIC design, fabrication, and packaging of the IRFPA manufactured by GWIC, especially on design for high sensitivities, low noise, better uniformity and linearity, better stabilization for whole working temperature range, full-digital design, etc.

Fast uncooled module 32×32 array of polycrystalline PbSe used for muzzle flash detection

NASA Astrophysics Data System (ADS)

Kastek, Mariusz; Dulski, Rafał; Trzaskawka, Piotr; Bieszczad, Grzegorz

2011-06-01

The paper presents some aspects of muzzle flash detection using low resolution polycrystalline PbSe uncooled 32×32 detectors array. This system for muzzle flash detection works in MWIR (3 - 5 microns) region and it is based on VPD (Vapor Phase Deposition) technology. The low density uncooled 32×32 array is suitable for being used in low cost IR imagers sensitive in the MWIR band with frame rates exceeding 1.000 Hz. The FPA detector, read-out electronics and processing electronics (allowing the implementation of some algorithms for muzzle flash detection) has been presented. The system has been tested at field test ground. Results of detection range measurement with two types of optical systems (wide and narrow field of view) have been shown. The initial results of testing of some algorithms for muzzle flash detection have been also presented.

Design, demonstration and testing of low F-number LWIR panoramic imaging relay optics

NASA Astrophysics Data System (ADS)

Furxhi, Orges; Frascati, Joe; Driggers, Ronald

2018-04-01

Panoramic imaging is inherently wide field of view. High sensitivity uncooled Long Wave Infrared (LWIR) imaging requires low F-number optics. These two requirements result in short back working distance designs that, in addition to being costly, are challenging to integrate with commercially available uncooled LWIR cameras and cores. Common challenges include the relocation of the shutter flag, custom calibration of the camera dynamic range and NUC tables, focusing, and athermalization. Solutions to these challenges add to the system cost and make panoramic uncooled LWIR cameras commercially unattractive. In this paper, we present the design of Panoramic Imaging Relay Optics (PIRO) and show imagery and test results with one of the first prototypes. PIRO designs use several reflective surfaces (generally two) to relay a panoramic scene onto a real, donut-shaped image. The PIRO donut is imaged on the focal plane of the camera using a commercially-off-the-shelf (COTS) low F-number lens. This approach results in low component cost and effortless integration with pre-calibrated commercially available cameras and lenses.

Improved integrated sniper location system

NASA Astrophysics Data System (ADS)

Figler, Burton D.; Spera, Timothy J.

1999-01-01

In July of 1995, Lockheed Martin IR Imaging Systems, of Lexington, Massachusetts began the development of an integrated sniper location system for the Defense Advanced Research Projects Agency and for the Department of the Navy's Naval Command Control & Ocean Surveillance Center, RDTE Division in San Diego, California. The I-SLS integrates acoustic and uncooled infrared sensing technologies to provide an affordable and highly effective sniper detection and location capability. This system, its performance and results from field tests at Camp Pendleton, California, in October 1996 were described in a paper presented at the November 1996 SPIE Photonics East Symposium1 on Enabling Technologies for Law Enforcement and Security. The I-SLS combines an acoustic warning system with an uncooled infrared warning system. The acoustic warning system has been developed by SenTech, Inc., of Lexington, Massachusetts. This acoustic warning system provides sniper detection and coarse location information based upon the muzzle blast of the sniper's weapon and/or upon the shock wave produced by the sniper's bullet, if the bullet is supersonic. The uncooled infrared warning system provides sniper detection and fine location information based upon the weapon's muzzle flash. In addition, the uncooled infrared warning system can provide thermal imagery that can be used to accurately locate and identify the sniper. Combining these two technologies improves detection probability, reduces false alarm rate and increases utility. In the two years since the last report of the integrated sniper location system, improvements have been made and a second field demonstration was planned. In this paper, we describe the integrated sniper location system modifications in preparation for the new field demonstration. In addition, fundamental improvements in the uncooled infrared sensor technology continue to be made. These improvements include higher sensitivity (lower minimum resolvable temperature), higher spatial resolution, and smaller size. This paper will describe the implementation and status of these improvements.

Numerical simulation of the flow and fuel-air mixing in an axisymmetric piston-cylinder arrangement

NASA Technical Reports Server (NTRS)

Shih, T. I. P.; Smith, G. E.; Springer, G. S.

1982-01-01

The implicit factored method of Beam and Warming was employed to describe the flow and the fuel-air mixing in an axisymmetric piston-cylinder configuration during the intake and compression strokes. The governing equations were established on the basis of laminar flow. The increased mixing due to turbulence was simulated by appropriately chosen effective transport properties. Calculations were performed for single-component gases and for two-component gases and for two-component gas mixtures. The flow field was calculated as functions of time and position for different geometries, piston speeds, intake-charge-to-residual-gas-pressure ratios, and species mass fractions of the intake charge. Results are presented in graphical form which show the formation, growth, and break-up of those vortices which form during the intake stroke and the mixing of fuel and air throughout the intake and compression strokes. It is shown that at bore-to-stroke ratio of less than unity, the vortices may break-up during the intake stroke. It is also shown that vortices which do not break-up during the intake stroke coalesce during the compression stroke. The results generated were compared to existing numerical solutions and to available experimental data.

Technology of uncooled fast polycrystalline PbSe focal plane arrays in systems for muzzle flash detection

NASA Astrophysics Data System (ADS)

Kastek, Mariusz; PiÄ tkowski, Tadeusz; Polakowski, Henryk; Barela, Jaroslaw; Firmanty, Krzysztof; Trzaskawka, Piotr; Vergara, German; Linares, Rodrigo; Gutierrez, Raul; Fernandez, Carlos; Montojo Supervielle, Maria Teresa

2014-05-01

The paper presents some aspects of muzzle flash detection using low resolution polycrystalline PbSe 32×32 and 80×80 detectors FPA operating at room temperature (uncooled performance). These sensors, which detect in MWIR (3 - 5 microns region) and are manufactured using proprietary technology from New Infrared Technologies (VPD PbSe - Vapor Phase Deposition of polycrystalline PbSe), can be applied to muzzle flash detection. The system based in the uncooled 80×80 FPA monolithically integrated with the CMOS readout circuitry has allowed image recording with frame rates over 2000 Hz (true snapshot acquisition), whereas the lower density, uncooled 32×32 FPA is suitable for being used in low cost infrared imagers sensitive in the MWIR band with frame rates above 1000 Hz. The FPA detector, read-out electronics and processing electronics (allows the implementation of some algorithms for muzzle flash detection) of both systems are presented. The systems have been tested at field test ground. Results of detection range measurement with two types of optical systems (wide and narrow field of view) have been shown. The theoretical analysis of possibility detection of muzzle flash and initial results of testing of some algorithms for muzzle flash detection have been presented too.

Uncooled microbolometer sensors for unattended applications

NASA Astrophysics Data System (ADS)

Kohin, Margaret; Miller, James E.; Leary, Arthur R.; Backer, Brian S.; Swift, William; Aston, Peter

2003-09-01

BAE SYSTEMS has been developing and producing uncooled microbolometer sensors since 1995. Recently, uncooled sensors have been used on Pointer Unattended Aerial Vehicles and considered for several unattended sensor applications including DARPA Micro-Internetted Unattended Ground Sensors (MIUGS), Army Modular Acoustic Imaging Sensors (MAIS), and Redeployable Unattended Ground Sensors (R-UGS). This paper describes recent breakthrough uncooled sensor performance at BAE SYSTEMS and how this improved performance has been applied to a new Standard Camera Core (SCC) that is ideal for these unattended applications. Video imagery from a BAE SYSTEMS 640x480 imaging camera flown in a Pointer UAV is provided. Recent performance results are also provided.

Uncooled infrared sensors for an integrated sniper location system

NASA Astrophysics Data System (ADS)

Spera, Timothy J.; Figler, Burton D.

1997-02-01

Since July of 1995, Lockheed Martin IR Imaging Systems of Lexington, Massachusetts has been developing an integrated sniper location system for the Advanced Research Projects Agency (ARPA) and for the Department of the Navy's Naval Command Control & Ocean Surveillance Center, RDTE Division in San Diego, California. This system integrates two technologies to provide an affordable and highly effective sniper detection and location capability. The integrated sniper location system is being developed for use by the military and by law enforcement agencies. It will be man portable and can be used by individuals, at fixed ground sites, on ground vehicles, and on low flying aircraft. The integrated sniper location system combines an acoustic warning system with an uncooled infrared warning system. The acoustic warner is being developed by SenTech, Inc. of Lexington, Massachusetts. This acoustic warner provides sniper detection and coarse location information based upon the muzzle blast of the sniper's weapon and/or upon the shock wave produced by the sniper's bullet, if the bullet is supersonic. The uncooled infrared warning system provides sniper detection and fine location information based upon the weapons's muzzle flash. Combining the two technologies improves detection probability and reduces false alarm rate. This paper describes the integrated sniper location system, focusing on the uncooled infrared sensor and its associated signal processing. In addition, preliminary results from Phase I testing of the system are presented. Finally, the paper addresses the plans for implementing Phases II and III, during which the system will be optimized in terms of detection and location performance, size, weight, power, and cost.

Thermopile Detector Arrays for Space Science Applications

NASA Technical Reports Server (NTRS)

Foote, M. C.; Kenyon, M.; Krueger, T. R.; McCann, T. A.; Chacon, R.; Jones, E. W.; Dickie, M. R.; Schofield, J. T.; McCleese, D. J.; Gaalema, S.

2004-01-01

Thermopile detectors are widely used in uncooled applications where small numbers of detectors are required, particularly in low-cost commercial applications or applications requiring accurate radiometry. Arrays of thermopile detectors, however, have not been developed to the extent of uncooled bolometer and pyroelectric/ferroelectric arrays. Efforts at JPL seek to remedy this deficiency by developing high performance thin-film thermopile detectors in both linear and two-dimensional formats. The linear thermopile arrays are produced by bulk micromachining and wire bonded to separate CMOS readout electronic chips. Such arrays are currently being fabricated for the Mars Climate Sounder instrument, scheduled for launch in 2005. Progress is also described towards realizing a two-dimensional thermopile array built over CMOS readout circuitry in the substrate.

Comparison of Theoretically and Experimentally Determined Effects of Oxide Coatings Supplied by Fuel Additives on Uncooled Turbine-blade Temperature During Transient Turbojet-engine Operation

NASA Technical Reports Server (NTRS)

Schafer, Louis J; Stepka, Francis S; Brown, W Byron

1953-01-01

An analysis was made to permit the calculation of the effectiveness of oxide coatings in retarding the transient heat flow into turbine blades when the combustion gas temperature of a turbojet engine is suddenly changed. The analysis is checked with experimental data obtained from a turbojet engine whose blades were coated with two different coating materials (silicon dioxide and boric oxide) by adding silicone oil and tributyl borate to the engine fuel. The very thin coatings (approximately 0.001 in.) that formed on the blades produced a negligible effect on the turbine-blade transient temperature response. With the analysis discussed here, it was possible to predict the turbine rotor-blade temperature response with a maximum error of 40 F.

Variable filter array spectrometer of VPD PbSe

NASA Astrophysics Data System (ADS)

Linares-Herrero, R.; Vergara, G.; Gutiérrez-Álvarez, R.; Fernández-Montojo, C.; Gómez, L. J.; Villamayor, V.; Baldasano-Ramírez, A.; Montojo, M. T.

2012-06-01

MWIR spectroscopy shows a large potential in the current IR devices market, due to its multiple applications (gas detection, chemical analysis, industrial monitoring, combustion and flame characterization, food packaging etc) and its outstanding performance (good sensitivity, NDT method, velocity of response, among others), opening this technique to very diverse fields of application, such as industrial monitoring and control, agriculture, medicine and environmental monitoring. However, even though a big interest on MWIR spectroscopy technique has been present in the last years, two major barriers have held it back from its widespread use outside the laboratory: the complexity and delicateness of some popular techniques such as Fourier-transform IR (FT-IR) spectrometers, and the lack of affordable specific key elements such a MWIR light sources and low cost (real uncooled) detectors. Recent developments in electrooptical components are helping to overcome these drawbacks. The need for simpler solutions for analytical measurements has prompted the development of better and more affordable uncooled MWIR detectors, electronics and optics. In this paper a new MWIR spectrometry device is presented. Based on linear arrays of different geometries (64, 128 and 256 elements), NIT has developed a MWIR Variable Filter Array Spectrometer (VFAS). This compact device, with no moving parts, based on a rugged and affordable detector, is suitable to be used in applications which demand high sensitivity, good spectral discrimination, reliability and compactness, and where an alternative to the traditional scanning instrument is desired. Some measurements carried out for several industries will be also presented.

Stirling cycle engine

DOEpatents

Lundholm, Gunnar

1983-01-01

In a Stirling cycle engine having a plurality of working gas charges separated by pistons reciprocating in cylinders, the total gas content is minimized and the mean pressure equalization among the serial cylinders is improved by using two piston rings axially spaced at least as much as the piston stroke and by providing a duct in the cylinder wall opening in the space between the two piston rings and leading to a source of minimum or maximum working gas pressure.

Gas Dynamic Modernization of Axial Uncooled Turbine by Means of CFD and Optimization Software

NASA Astrophysics Data System (ADS)

Marchukov, E. Yu; Egorov, I. N.

2018-01-01

The results of multicriteria optimization of three-stage low-pressure turbine are described in the paper. The aim of the optimization is to improve turbine operation process by three criteria: turbine outlet flow angle, value of residual swirl at the turbine outlet, and turbine efficiency. Full reprofiling of all blade rows is carried out while solving optimization problem. Reprofiling includes a change in both shape of flat blade sections (profiles) and three-dimensional shape of the blades. The study is carried out with 3D numerical models of turbines.

2004 Army Research Office in Review

DTIC Science & Technology

2004-01-01

23 Uncool Tunable LWIR Microbolometer...but also for speech in multimedia applications. ELECTRONICS Uncooled Tunable LWIR Microbolometer – Multi- or hyper- spectral images contain...Analysis of NURBS Curves and Surfaces Jian-Ao Lian, Prairie View A&M University The multiresolution structure of NURBS ( nonuniform rational B

Thermoelectric bolometers based on silicon membranes

NASA Astrophysics Data System (ADS)

Varpula, Aapo; Timofeev, Andrey V.; Shchepetov, Andrey; Grigoras, Kestutis; Ahopelto, Jouni; Prunnila, Mika

2017-05-01

State-of-the-art high performance IR sensing and imaging systems utilize highly expensive photodetector technology, which requires exotic and toxic materials and cooling. Cost-effective alternatives, uncooled bolometer detectors, are widely used in commercial long-wave IR (LWIR) systems. Compared to the cooled detectors they are much slower and have approximately an order of magnitude lower detectivity in the LWIR. We present uncooled bolometer technology which is foreseen to be capable of narrowing the gap between the cooled and uncooled technologies. The proposed technology is based on ultra-thin silicon membranes, the thermal conductivity and electrical properties of which can be controlled by membrane thickness and doping, respectively. The thermal signal is transduced into electric voltage using thermocouple consisting of highly-doped n and p type Si beams. Reducing the thickness of the Si membrane improves the performance (i.e. sensitivity and speed) as thermal conductivity and thermal mass of Si membrane decreases with decreasing thickness. Based on experimental data we estimate the performance of these uncooled thermoelectric bolometers.

Lead salt room-temperature MWIR FPA

NASA Astrophysics Data System (ADS)

Murphy, Paul F.; Jost, Steven R.; Barrett, John L.; Reese, Dan; Winn, Michael L.

2001-10-01

The development of low-cost uncooled thermal LWIR FPAs is resulting in the emergence of a new generation of infrared sensors for applications where affordability is the prerequisite for volume production. Both ferroelectric detector arrays and silicon-based microbolometers are finding numerous applications from gun sights to automotive FLIRs. There would be significant interest in a similar uncooled offering in the MWIR, but to date, thermal detectors have lacked sufficient sensitivity. The existing uncooled MWIR photon detector technology, based on polycrystalline lead salts, has been relegated to single-element detectors and relatively small linear arrays due to the high dark current and the stigma of being a 50-year-old technology.

Improved calibration-based non-uniformity correction method for uncooled infrared camera

NASA Astrophysics Data System (ADS)

Liu, Chengwei; Sui, Xiubao

2017-08-01

With the latest improvements of microbolometer focal plane arrays (FPA), uncooled infrared (IR) cameras are becoming the most widely used devices in thermography, especially in handheld devices. However the influences derived from changing ambient condition and the non-uniform response of the sensors make it more difficult to correct the nonuniformity of uncooled infrared camera. In this paper, based on the infrared radiation characteristic in the TEC-less uncooled infrared camera, a novel model was proposed for calibration-based non-uniformity correction (NUC). In this model, we introduce the FPA temperature, together with the responses of microbolometer under different ambient temperature to calculate the correction parameters. Based on the proposed model, we can work out the correction parameters with the calibration measurements under controlled ambient condition and uniform blackbody. All correction parameters can be determined after the calibration process and then be used to correct the non-uniformity of the infrared camera in real time. This paper presents the detail of the compensation procedure and the performance of the proposed calibration-based non-uniformity correction method. And our method was evaluated on realistic IR images obtained by a 384x288 pixels uncooled long wave infrared (LWIR) camera operated under changed ambient condition. The results show that our method can exclude the influence caused by the changed ambient condition, and ensure that the infrared camera has a stable performance.

Numerical simulation of the flow field and fuel sprays in an IC engine

NASA Technical Reports Server (NTRS)

Nguyen, H. L.; Schock, H. J.; Ramos, J. I.; Carpenter, M. H.; Stegeman, J. D.

1987-01-01

A two-dimensional model for axisymmetric piston-cylinder configurations is developed to study the flow field in two-stroke direct-injection Diesel engines under motored conditions. The model accounts for turbulence by a two-equation model for the turbulence kinetic energy and its rate of dissipation. A discrete droplet model is used to simulate the fuel spray, and the effects of the gas phase turbulence on the droplets is considered. It is shown that a fluctuating velocity can be added to the mean droplet velocity every time step if the step is small enough. Good agreement with experimental data is found for a range of ambient pressures in Diesel engine-type microenvironments. The effects of the intake swirl angle in the spray penetration, vaporization, and mixing in a uniflow-scavenged two-stroke Diesel engine are analyzed. It is found that the swirl increases the gas phase turbulence levels and the rates of vaporization.

Cost/benefit analysis of advanced material technologies for small aircraft turbine engines

NASA Technical Reports Server (NTRS)

Comey, D. H.

1977-01-01

Cost/benefit studies were conducted on ten advanced material technologies applicable to small aircraft gas turbine engines to be produced in the 1985 time frame. The cost/benefit studies were applied to a two engine, business-type jet aircraft in the 6800- to 9100-Kg (15,000- to 20,000-lb) gross weight class. The new material technologies are intended to provide improvements in the areas of high-pressure turbine rotor components, high-pressure turbine rotor components, high-pressure turbine stator airfoils, and static structural components. The cost/benefit of each technology is presented in terms of relative value, which is defined as a change in life cycle cost times probability of success divided by development cost. Technologies showing the most promising cost/benefits based on relative value are uncooled single crystal MAR-M 247 turbine blades, cooled DS MAR-M 247 turbine blades, and cooled ODS 'M'CrAl laminate turbine stator vanes.

Nonuniformity correction based on focal plane array temperature in uncooled long-wave infrared cameras without a shutter.

PubMed

Liang, Kun; Yang, Cailan; Peng, Li; Zhou, Bo

2017-02-01

In uncooled long-wave IR camera systems, the temperature of a focal plane array (FPA) is variable along with the environmental temperature as well as the operating time. The spatial nonuniformity of the FPA, which is partly affected by the FPA temperature, obviously changes as well, resulting in reduced image quality. This study presents a real-time nonuniformity correction algorithm based on FPA temperature to compensate for nonuniformity caused by FPA temperature fluctuation. First, gain coefficients are calculated using a two-point correction technique. Then offset parameters at different FPA temperatures are obtained and stored in tables. When the camera operates, the offset tables are called to update the current offset parameters via a temperature-dependent interpolation. Finally, the gain coefficients and offset parameters are used to correct the output of the IR camera in real time. The proposed algorithm is evaluated and compared with two representative shutterless algorithms [minimizing the sum of the squares of errors algorithm (MSSE), template-based solution algorithm (TBS)] using IR images captured by a 384×288 pixel uncooled IR camera with a 17 μm pitch. Experimental results show that this method can quickly trace the response drift of the detector units when the FPA temperature changes. The quality of the proposed algorithm is as good as MSSE, while the processing time is as short as TBS, which means the proposed algorithm is good for real-time control and at the same time has a high correction effect.

Carbon Nanostructure of Diesel Soot Particles Emitted from 2 and 4 Stroke Marine Engines Burning Different Fuels.

PubMed

Lee, Won-Ju; Park, Seul-Hyun; Jang, Se-Hyun; Kim, Hwajin; Choi, Sung Kuk; Cho, Kwon-Hae; Cho, Ik-Soon; Lee, Sang-Min; Choi, Jae-Hyuk

2018-03-01

Diesel soot particles were sampled from 2-stroke and 4-stroke engines that burned two different fuels (Bunker A and C, respectively), and the effects of the engine and fuel types on the structural characteristics of the soot particle were analyzed. The carbon nanostructures of the sampled particles were characterized using various techniques. The results showed that the soot sample collected from the 4-stroke engine, which burned Bunker C, has a higher degree of order of the carbon nanostructure than the sample collected from the 2-stroke engine, which burned Bunker A. Furthermore, the difference in the exhaust gas temperatures originating from the different engine and fuel types can affect the nanostructure of the soot emitted from marine diesel engines.

Effects of internal electrode cooling on irreversible electroporation using a perfused organ model.

PubMed

O'Brien, Timothy J; Bonakdar, Mohammad; Bhonsle, Suyashree; Neal, Robert E; Aardema, Charles H; Robertson, John L; Goldberg, S Nahum; Davalos, Rafael V

2018-05-28

This study evaluates the effects of active electrode cooling, via internal fluid circulation, on the irreversible electroporation (IRE) lesion, deployed electric current and temperature changes using a perfused porcine liver model. A bipolar electrode delivered IRE electric pulses with or without activation of internal cooling to nine porcine mechanically perfused livers. Pulse schemes included a constant voltage, and a preconditioned delivery combined with an arc-mitigation algorithm. After treatment, organs were dissected, and treatment zones were stained using triphenyl-tetrazolium chloride (TTC) to demonstrate viability. Thirty-nine treatments were performed with an internally cooled applicator and 21 with a non-cooled applicator. For the constant voltage scenario, the average final electrical current measured was 26.37 and 29.20 A for the cooled and uncooled electrodes respectively ([Formula: see text]). The average final temperature measured was 33.01 and 42.43 °C for the cooled and uncooled electrodes respectively ([Formula: see text]). The average measured ablations (fixed lesion) were 3.88-by-2.08 cm and 3.86-by-2.12 cm for the cooled and uncooled electrode respectively ([Formula: see text], [Formula: see text]). Similarly, the preconditioned/arc-mitigation scenario yielded an average final electrical current measurement of a 41.07 and 47.20 A for the cooled and uncooled electrodes respectively ([Formula: see text]). The average final temperature measured was 34.93 and 44.90 °C for the cooled and uncooled electrodes respectively ([Formula: see text]). The average measured ablations (fixed lesion) were 3.67-by-2.27 cm and 3.58-by-2.09 cm for the cooled and uncooled applicators ([Formula: see text]). The internally-cooled bipolar applicator offers advantages that could improve clinical outcomes. Thermally mitigating internal perfusion technology reduced tissue temperatures and electric current while maintaining similar lesion sizes.

Uncooled emissive infrared imagers for CubeSats

NASA Astrophysics Data System (ADS)

Puschell, Jeffery J.; Masini, Paolo

2014-09-01

Raytheon's fourth generation uncooled microbolometer array technology with digital output, High Definition (HD) 1920 × 1200 format and 12 μm cell size enables uncooled thermal infrared (TIR) multispectral imagers with the sensitivity and spatial sampling needed for a variety of Earth observation missions in LEO, GEO and HEO. A powerful combination of small detector cell size, fast optics and high sensitivity achieved without cryogenic cooling leads to instruments that are much smaller than current TIR systems, while still offering the capability to meet challenging measurement requirements for Earth observation missions. To consider how this technology could be implemented for Earth observation missions, we extend our previous studies with visible wavelength CubeSat imagers for environmental observations from LEO and examine whether small thermal infrared imagers based on fourth generation uncooled technology could be made small enough to fit onboard a 3U CubeSat and still meet challenging requirements for legacy missions. We found that moderate spatial resolution (~200 m) high sensitivity cloud and surface temperature observations meeting legacy MODIS/VIIRS requirements could be collected successfully with CubeSat-sized imagers but that multiple imagers are needed to cover the full swath for these missions. Higher spatial resolution land imagers are more challenging to fit into the CubeSat form factor, but it may be possible to do so for systems that require roughly 100 m spatial resolution. Regardless of whether it can fit into a CubeSat or not, uncooled land imagers meeting candidate TIR requirements can be implemented with a much smaller instrument than previous imagers. Even though this technology appears to be very promising, more work is needed to qualify this newly available uncooled infrared technology for use in space. If these new devices prove to be as space worthy as the first generation arrays that Raytheon qualified and built into the THEMIS imager still operating successfully onboard Mars Odyssey 2001, new classes of low cost, uncooled TIR Earth instruments will be enabled that are suitable for use as primary and hosted payloads in LEO, GEO and HEO or in constellations of small satellites as small as CubeSats to support Earth science measurement objectives in weather forecasting, land imaging and climate variability and change.

Extension of spectral range of Peltier cooled photodetectors to 16 μm

NASA Astrophysics Data System (ADS)

Piotrowski, A.; Piotrowski, J.; Gawron, W.; Pawluczyk, J.; Pedzinska, M.

2009-05-01

We have developed various types of photodetectors operating without cryocooling. Initially, the devices were mostly used for uncooled detection of CO2 laser radiation. Over the years the performance and speed of response has been steadily improved. At present the uncooled or Peltier cooled photodetectors can be used for sensitive and fast response detection in the MWIR and LWIR spectral range. The devices have found important applications in IR spectrometry, quantum cascade laser based gas analyzers, laser radiation alerters and many other IR systems. Recent efforts were concentrated on the extension of useful spectral range to >13 μm, as required for its application in FTIR spectrometers. This was achieved with improved design of the active elements, use of monolithic optical immersion technology, enhanced absorption of radiation, dedicated electronics, series connection of small cells in series, and last but not least, applying more efficient Peltier coolers. Practical devices are based on the complex HgCdTe heterostructures grown on GaAs substrates with MOCVD technique with immersion lens formed by micromachining in the GaAs substrates. The results are very encouraging. The devices cooled with miniature 4 stage Peltier coolers mounted in TO-8 style housings show significant response at wavelength exceeding 16 μm.

The Cool vs. The Uncool. Your Middle School Classroom

ERIC Educational Resources Information Center

Barnes, Peter

2005-01-01

Social cliques start around fourth or fifth grade and get worse through middle school and beyond. The cool vs. the uncool. Nerds, jocks, popular kids and outsiders--students are categorized by their peers and excluded by those different from them. Students who are not part of the "cool" crowd feel isolated and lonely and are often subjected to…

Solution-processed nanoparticle super-float-gated organic field-effect transistor as un-cooled ultraviolet and infrared photon counter.

PubMed

Yuan, Yongbo; Dong, Qingfeng; Yang, Bin; Guo, Fawen; Zhang, Qi; Han, Ming; Huang, Jinsong

2013-01-01

High sensitivity photodetectors in ultraviolet (UV) and infrared (IR) range have broad civilian and military applications. Here we report on an un-cooled solution-processed UV-IR photon counter based on modified organic field-effect transistors. This type of UV detectors have light absorbing zinc oxide nanoparticles (NPs) sandwiched between two gate dielectric layers as a floating gate. The photon-generated charges on the floating gate cause high resistance regions in the transistor channel and tune the source-drain output current. This "super-float-gating" mechanism enables very high sensitivity photodetectors with a minimum detectable ultraviolet light intensity of 2.6 photons/μm(2)s at room temperature as well as photon counting capability. Based on same mechansim, infrared photodetectors with lead sulfide NPs as light absorbing materials have also been demonstrated.

Recent progress in infrared detector technologies

NASA Astrophysics Data System (ADS)

Rogalski, A.

2011-05-01

In the paper, fundamental and technological issues associated with the development and exploitation of the most advanced infrared detector technologies are discussed. In this class of detectors both photon and thermal detectors are considered. Special attention is directed to HgCdTe ternary alloys on silicon, type-II superlattices, uncooled thermal bolometers, and novel uncooled micromechanical cantilever detectors. Despite serious competition from alternative technologies and slower progress than expected, HgCdTe is unlikely to be seriously challenged for high-performance applications, applications requiring multispectral capability and fast response. However, the nonuniformity is a serious problem in the case of LWIR and VLWIR HgCdTe detectors. In this context, it is predicted that type-II superlattice system seems to be an alternative to HgCdTe in long wavelength spectral region. In well established uncooled imaging, microbolometer arrays are clearly the most used technology. Present state-of-the-art microbolometers are based on polycrystalline or amorphous materials, typically vanadium oxide (VO x) or amorphous silicon (α-Si), with only modest temperature sensitivity and noise properties. Basic efforts today are mainly focused on pixel reduction and performance enhancement. Attractive alternatives consist of low-resistance α-SiGe monocrystalline SiGe quantum wells or quantum dots. In spite of successful commercialization of uncooled microbolometers, the infrared community is still searching for a platform for thermal imagers that combine affordability, convenience of operation, and excellent performance. Recent advances in MEMS systems have lead to the development of uncooled IR detectors operating as micromechanical thermal detectors. Between them the most important are biomaterial microcantilevers.

Uncooled radiometric camera performance

NASA Astrophysics Data System (ADS)

Meyer, Bill; Hoelter, T.

1998-07-01

Thermal imaging equipment utilizing microbolometer detectors operating at room temperature has found widespread acceptance in both military and commercial applications. Uncooled camera products are becoming effective solutions to applications currently using traditional, photonic infrared sensors. The reduced power consumption and decreased mechanical complexity offered by uncooled cameras have realized highly reliable, low-cost, hand-held instruments. Initially these instruments displayed only relative temperature differences which limited their usefulness in applications such as Thermography. Radiometrically calibrated microbolometer instruments are now available. The ExplorIR Thermography camera leverages the technology developed for Raytheon Systems Company's first production microbolometer imaging camera, the Sentinel. The ExplorIR camera has a demonstrated temperature measurement accuracy of 4 degrees Celsius or 4% of the measured value (whichever is greater) over scene temperatures ranges of minus 20 degrees Celsius to 300 degrees Celsius (minus 20 degrees Celsius to 900 degrees Celsius for extended range models) and camera environmental temperatures of minus 10 degrees Celsius to 40 degrees Celsius. Direct temperature measurement with high resolution video imaging creates some unique challenges when using uncooled detectors. A temperature controlled, field-of-view limiting aperture (cold shield) is not typically included in the small volume dewars used for uncooled detector packages. The lack of a field-of-view shield allows a significant amount of extraneous radiation from the dewar walls and lens body to affect the sensor operation. In addition, the transmission of the Germanium lens elements is a function of ambient temperature. The ExplorIR camera design compensates for these environmental effects while maintaining the accuracy and dynamic range required by today's predictive maintenance and condition monitoring markets.

Primary gas- and particle-phase emissions and secondary organic aerosol production from gasoline and diesel off-road engines.

PubMed

Gordon, Timothy D; Tkacik, Daniel S; Presto, Albert A; Zhang, Mang; Jathar, Shantanu H; Nguyen, Ngoc T; Massetti, John; Truong, Tin; Cicero-Fernandez, Pablo; Maddox, Christine; Rieger, Paul; Chattopadhyay, Sulekha; Maldonado, Hector; Maricq, M Matti; Robinson, Allen L

2013-12-17

Dilution and smog chamber experiments were performed to characterize the primary emissions and secondary organic aerosol (SOA) formation from gasoline and diesel small off-road engines (SOREs). These engines are high emitters of primary gas- and particle-phase pollutants relative to their fuel consumption. Two- and 4-stroke gasoline SOREs emit much more (up to 3 orders of magnitude more) nonmethane organic gases (NMOGs), primary PM and organic carbon than newer on-road gasoline vehicles (per kg of fuel burned). The primary emissions from a diesel transportation refrigeration unit were similar to those of older, uncontrolled diesel engines used in on-road vehicles (e.g., premodel year 2007 heavy-duty diesel trucks). Two-strokes emitted the largest fractional (and absolute) amount of SOA precursors compared to diesel and 4-stroke gasoline SOREs; however, 35-80% of the NMOG emissions from the engines could not be speciated using traditional gas chromatography or high-performance liquid chromatography. After 3 h of photo-oxidation in a smog chamber, dilute emissions from both 2- and 4-stroke gasoline SOREs produced large amounts of semivolatile SOA. The effective SOA yield (defined as the ratio of SOA mass to estimated mass of reacted precursors) was 2-4% for 2- and 4-stroke SOREs, which is comparable to yields from dilute exhaust from older passenger cars and unburned gasoline. This suggests that much of the SOA production was due to unburned fuel and/or lubrication oil. The total PM contribution of different mobile source categories to the ambient PM burden was calculated by combining primary emission, SOA production and fuel consumption data. Relative to their fuel consumption, SOREs are disproportionately high total PM sources; however, the vastly greater fuel consumption of on-road vehicles renders them (on-road vehicles) the dominant mobile source of ambient PM in the Los Angeles area.

Monolithic Silicon Microbolometer Materials forUncooled Infrared Detectors

DTIC Science & Technology

2015-05-21

L. Allara, Mark W. Horn. Vanadium Oxide Thin Films Alloyed with Ti, Zr , Nb , and Mo for Uncooled Infrared Imaging Applications, Journal of...entitled "Thin Film Materials and Devices for Resistive Temperature Sensing Applications" by Hitesh Basantani and the other entitled "Reactive...extension. One was entitled "Thin Film Materials and Devices for Resistive Temperature Sensing Applications" by Hitesh Basantani and the other

Variable gas spring for matching power output from FPSE to load of refrigerant compressor

DOEpatents

Chen, Gong; Beale, William T.

1990-01-01

The power output of a free piston Stirling engine is matched to a gas compressor which it drives and its stroke amplitude is made relatively constant as a function of power by connecting a gas spring to the drive linkage from the engine to the compressor. The gas spring is connected to the compressor through a passageway in which a valve is interposed. The valve is linked to the drive linkage so it is opened when the stroke amplitude exceeds a selected limit. This allows compressed gas to enter the spring, increase its spring constant, thus opposing stroke increase and reducing the phase lead of the displacer ahead of the piston to reduce power output and match it to a reduced load power demand.

Variable gas spring for matching power output from FPSE to load of refrigerant compressor

DOEpatents

Chen, G.; Beale, W.T.

1990-04-03

The power output of a free piston Stirling engine is matched to a gas compressor which it drives and its stroke amplitude is made relatively constant as a function of power by connecting a gas spring to the drive linkage from the engine to the compressor. The gas spring is connected to the compressor through a passageway in which a valve is interposed. The valve is linked to the drive linkage so it is opened when the stroke amplitude exceeds a selected limit. This allows compressed gas to enter the spring, increase its spring constant, thus opposing stroke increase and reducing the phase lead of the displacer ahead of the piston to reduce power output and match it to a reduced load power demand. 6 figs.

Terahertz Real-Time Imaging Uncooled Arrays Based on Antenna-Coupled Bolometers or FET Developed at CEA-Leti

NASA Astrophysics Data System (ADS)

Simoens, François; Meilhan, Jérôme; Nicolas, Jean-Alain

2015-10-01

Sensitive and large-format terahertz focal plane arrays (FPAs) integrated in compact and hand-held cameras that deliver real-time terahertz (THz) imaging are required for many application fields, such as non-destructive testing (NDT), security, quality control of food, and agricultural products industry. Two technologies of uncooled THz arrays that are being studied at CEA-Leti, i.e., bolometer and complementary metal oxide semiconductor (CMOS) field effect transistors (FET), are able to meet these requirements. This paper reminds the followed technological approaches and focuses on the latest modeling and performance analysis. The capabilities of application of these arrays to NDT and security are then demonstrated with experimental tests. In particular, high technological maturity of the THz bolometer camera is illustrated with fast scanning of large field of view of opaque scenes achieved in a complete body scanner prototype.

High-MTF hybrid ferroelectric IRFPA

NASA Astrophysics Data System (ADS)

Evans, Scott B.; Hayden, Terrence

1998-07-01

Low cost, uncooled hybrid infrared focal plane arrays (IRFPA's) are in full-scale production at Raytheon Systems Company (RSC), formerly Texas Instruments Defense Systems and Electronics Group. Detectors consist of reticulated ceramic barium strontium titanate (BST) arrays of 320 X 240 pixels on 48.5 micrometer pitch. The principal performance shortcoming of the hybrid arrays has been low MTF due to thermal crosstalk between pixels. In the past two years, significant improvements have been made to increase MTF making hybrids more competitive in performance with monolithic arrays. The improvements are (1) the reduction of the thickness of the IR absorbing layer electrode that maintains electrical continuity and increases thermal isolation between pixels, (2) reduction of the electrical crosstalk from the ROIC, and (3) development of a process to increase the thermal path-length between pixels called 'elevated optical coat.' This paper describes all three activities and their efficacy. Also discussed is the uncooled IRFPA production capability at RSC.

Uncooled tunneling infrared sensor

NASA Technical Reports Server (NTRS)

Kenny, Thomas W. (Inventor); Kaiser, William J. (Inventor); Podosek, Judith A. (Inventor); Vote, Erika C. (Inventor); Rockstad, Howard K. (Inventor); Reynolds, Joseph K. (Inventor)

1994-01-01

An uncooled infrared tunneling sensor in which the only moving part is a diaphragm which is deflected into contact with a micromachined silicon tip electrode prepared by a novel lithographic process. Similarly prepared deflection electrodes employ electrostatic force to control the deflection of a silicon nitride, flat diaphragm membrane. The diaphragm exhibits a high resonant frequency which reduces the sensor's sensitivity to vibration. A high bandwidth feedback circuit controls the tunneling current by adjusting the deflection voltage to maintain a constant deflection of the membrane which would otherwise change deflection depending upon incident infrared radiation. The resulting infrared sensor will meet or exceed the performance of all other broadband, uncooled, infrared sensors and can be miniaturized to pixel dimensions smaller than 100 .mu.m. The technology is readily implemented as a small-format linear array suitable for commercial and spacecraft applications.

TANDIR: projectile warning system using uncooled bolometric technology

NASA Astrophysics Data System (ADS)

Horovitz-Limor, Z.; Zahler, M.

2007-04-01

Following the demand for affordable, various range and light-weight protection against ATGM's, Elisra develops a cost-effective passive IR system for ground vehicles. The system is based on wide FOV uncooled bolometric sensors with full azimuth coverage and a lightweight processing & control unit. The system design is based on the harsh environmental conditions. The basic algorithm discriminates the target from its clutter and predicts the time to impact (TTI) and the target aiming direction with relation to vehicle. The current detector format is 320*240 pixels and frame rate is 60 Hz, Spectral response is on Far Infrared (8-14μ). The digital video output has 14bit resolution & wide dynamic range. Future goal is to enhance detection performance by using large format uncooled detector (640X480) with improved sensitivity and higher frame rates (up to 120HZ).

Shutterless non-uniformity correction for the long-term stability of an uncooled long-wave infrared camera

NASA Astrophysics Data System (ADS)

Liu, Chengwei; Sui, Xiubao; Gu, Guohua; Chen, Qian

2018-02-01

For the uncooled long-wave infrared (LWIR) camera, the infrared (IR) irradiation the focal plane array (FPA) receives is a crucial factor that affects the image quality. Ambient temperature fluctuation as well as system power consumption can result in changes of FPA temperature and radiation characteristics inside the IR camera; these will further degrade the imaging performance. In this paper, we present a novel shutterless non-uniformity correction method to compensate for non-uniformity derived from the variation of ambient temperature. Our method combines a calibration-based method and the properties of a scene-based method to obtain correction parameters at different ambient temperature conditions, so that the IR camera performance can be less influenced by ambient temperature fluctuation or system power consumption. The calibration process is carried out in a temperature chamber with slowly changing ambient temperature and a black body as uniform radiation source. Enough uniform images are captured and the gain coefficients are calculated during this period. Then in practical application, the offset parameters are calculated via the least squares method based on the gain coefficients, the captured uniform images and the actual scene. Thus we can get a corrected output through the gain coefficients and offset parameters. The performance of our proposed method is evaluated on realistic IR images and compared with two existing methods. The images we used in experiments are obtained by a 384× 288 pixels uncooled LWIR camera. Results show that our proposed method can adaptively update correction parameters as the actual target scene changes and is more stable to temperature fluctuation than the other two methods.

Climate change impact on microclimate of work environment related to occupational health and productivity.

PubMed

Marchetti, Enrico; Capone, Pasquale; Freda, Daniela

2016-01-01

Climate change is a global emergency that influences human health and occupational safety. Global warming characterized by an increase in temperature of the ambience and humidity affects human health directly impairing body thermoregulation with serious consequences: dehydration, fatigue, heat stroke and even death. Several studies have demonstrated negative effects of climate change on working populations in a wide variety of workplaces with particular regard to outdoor and uncooled indoor workplaces. Most vulnerable workers are outdoor workers in tropical and subtropical countries usually involved in heavy labor during hot seasons. Many of the consequences therefore, regarding working people are possible, even without health symptoms by reducing work productivity. The scope of this review is to investigate effects of climate change on workers both in relation to health and work productivity. This study has been realized by analyzing recent international literature. In order to reduce negative effects of climate change on working populations it is essential to implement preventive measures with a multidisciplinary strategy limiting health risks and improving work productivity.

The role of nitrous oxide in stroke

PubMed Central

Zhang, Zhu-wei; Zhang, Dong-ping; Li, Hai-ying; Wang, Zhong; Chen, Gang

2017-01-01

Stroke that is caused by poor blood flow into the brain results in cell death, including ischemia stroke due to lack of blood into brain tissue, and hemorrhage due to bleeding. Both of them will give rise to the dysfunction of brain. In general, the signs and symptoms of stroke are the inability of feeling or moving on one side of body, sometimes loss of vision to one side. Above symptoms will appear soon after the stroke has happened. If the symptoms and signs happen in 1 or 2 hours, we often call them as transient ischemic attack. Moreover, hemorrhagic stroke often leads to severe headache. It is known that neuronal death can happen after stroke, and it depends upon the activation of N-methyl-D-aspartate (NMDA) excitatory glutamate receptor which is the goal for a lot of neuroprotective agents. Nitrous oxide was discovered by Joseph Priestley in 1772, and then he and his friends, including the poet Coleridge and Robert Sauce, experimented with the gas. They found this gas could make patients loss the sense of pain and still maintain consciousness after inhalation. Shortly the gas was used as an anesthetic, especially in the field of dentists. Now, accroding to theme of Helene N. David and other scientists, both of nitrous oxide at 75 vol% and xenon at 50 vol% could reduce ischemic neuronal death in the cortex by 70% and decrease NMDA-induced Ca2+ influx by 30%. Therefore, more clinical and experimental studies are important to illuminate the mechanisms of how nitrous oxide protects brain tissue and to explore the best protocol of this gas in stroke treatment. PMID:29497489

Solid state temperature-dependent NUC (non-uniformity correction) in uncooled LWIR (long-wave infrared) imaging system

NASA Astrophysics Data System (ADS)

Cao, Yanpeng; Tisse, Christel-Loic

2013-06-01

In uncooled LWIR microbolometer imaging systems, temperature fluctuations of FPA (Focal Plane Array) as well as lens and mechanical components placed along the optical path result in thermal drift and spatial non-uniformity. These non-idealities generate undesirable FPN (Fixed-Pattern-Noise) that is difficult to remove using traditional, individual shutterless and TEC-less (Thermo-Electric Cooling) techniques. In this paper we introduce a novel single-image based processing approach that marries the benefits of both statistical scene-based and calibration-based NUC algorithms, without relying neither on extra temperature reference nor accurate motion estimation, to compensate the resulting temperature-dependent non-uniformities. Our method includes two subsequent image processing steps. Firstly, an empirical behavioral model is derived by calibrations to characterize the spatio-temporal response of the microbolometric FPA to environmental and scene temperature fluctuations. Secondly, we experimentally establish that the FPN component caused by the optics creates a spatio-temporally continuous, low frequency, low-magnitude variation of the image intensity. We propose to make use of this property and learn a prior on the spatial distribution of natural image gradients to infer the correction function for the entire image. The performance and robustness of the proposed temperature-adaptive NUC method are demonstrated by showing results obtained from a 640×512 pixels uncooled LWIR microbolometer imaging system operating over a broad range of temperature and with rapid environmental temperature changes (i.e. from -5°C to 65°C within 10 minutes).

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

Kagan, Daniel; Nakar, Ehud; Piran, Tsvi, E-mail: daniel.kagan@mail.huji.ac.il

The maximum synchrotron burnoff limit of 160 MeV represents a fundamental limit to radiation resulting from electromagnetic particle acceleration in one-zone ideal plasmas. In magnetic reconnection, however, particle acceleration and radiation are decoupled because the electric field is larger than the magnetic field in the diffusion region. We carry out two-dimensional particle-in-cell simulations to determine the extent to which magnetic reconnection can produce synchrotron radiation above the burnoff limit. We use the test particle comparison (TPC) method to isolate the effects of cooling by comparing the trajectories and acceleration efficiencies of test particles incident on such a reconnection region withmore » and without cooling them. We find that the cooled and uncooled particle trajectories are typically similar during acceleration in the reconnection region, and derive an effective limit on particle acceleration that is inversely proportional to the average magnetic field experienced by the particle during acceleration. Using the calculated distribution of this average magnetic field as a function of uncooled final particle energy, we find analytically that cooling does not affect power-law particle energy spectra except at energies far above the synchrotron burnoff limit. Finally, we compare fully cooled and uncooled simulations of reconnection, confirming that the synchrotron burnoff limit does not produce a cutoff in the particle energy spectrum. Our results indicate that the TPC method accurately predicts the effects of cooling on particle acceleration in relativistic reconnection, and that, even far above the burnoff limit, the synchrotron energy of radiation produced in reconnection is not limited by cooling.« less

Bibliography of Research Reports and Publications Issued by the Human Engineering Division, January 1987 - December 1993

DTIC Science & Technology

1994-03-01

cues in an aircraft simulator. AMAA Flight Simulation Technologies Conference, 63- 70. Marasco , P. L., & Dereniak, E. L. (1993). Uncooled infrared...Space Center, TX: National Aeronautics and Space Administration. Task, H. L., Hartman, R. T., Marasco , P. L., & Zobel, A. R. (1993). Methods for...Aerospace VIIJ Conference, 2, 623-644. Marasco , P. L., & Dereniak, E. L. (1993). Uncooled infrared sensor performance. In B. F. Andresen, & F. D

Helmet-mounted uncooled FPA camera for use in firefighting applications

NASA Astrophysics Data System (ADS)

Wu, Cheng; Feng, Shengrong; Li, Kai; Pan, Shunchen; Su, Junhong; Jin, Weiqi

2000-05-01

From the concept and need background of firefighters to the thermal imager, we discuss how the helmet-mounted camera applied in the bad environment of conflagration, especially at the high temperature, and how the better matching between the thermal imager with the helmet will be put into effect in weight, size, etc. Finally, give a practical helmet- mounted IR camera based on the uncooled focal plane array detector for in firefighting.

Uncooled infrared sensors: rapid growth and future perspective

NASA Astrophysics Data System (ADS)

Balcerak, Raymond S.

2000-07-01

The uncooled infrared cameras are now available for both the military and commercial markets. The current camera technology incorporates the fruits of many years of development, focusing on the details of pixel design, novel material processing, and low noise read-out electronics. The rapid insertion of cameras into systems is testimony to the successful completion of this 'first phase' of development. In the military market, the first uncooled infrared cameras will be used for weapon sights, driver's viewers and helmet mounted cameras. Major commercial applications include night driving, security, police and fire fighting, and thermography, primarily for preventive maintenance and process control. The technology for the next generation of cameras is even more demanding, but within reach. The paper outlines the technology program planned for the next generation of cameras, and the approaches to further enhance performance, even to the radiation limit of thermal detectors.

Advanced uncooled infrared focal plane development at CEA/LETI

NASA Astrophysics Data System (ADS)

Tissot, Jean-Luc; Mottin, Eric; Martin, Jean-Luc; Yon, Jean-Jacques; Vilain, Michel

2017-11-01

LETI/LIR has been involved for a few year in the field of uncooled detectors and has chosen amorphous silicon for its microbolometer technology development. Uncooled IR detectors pave the way to reduced weight systems aboard satellites. The silicon compatibility of our thermometer is a key parameter which has enabled a very fast technology development and transfer to industry. This competitive technology is now able to provide a new approach for IR detectors for space applications. This paper presents the main characteristics of the CEA / LETI technology which is based on a monolithically integrated structure over a fully completed readout circuit from a commercially available 0.5 μm design rules CMOS line. The technology maturity will be illustrated by the results obtained at LETI/LIR and SOFRADIR on a 320 x 240 with a pitch of 45 μm. First improvement on device reliability and characterization results will be presented.

Characterization and initial field test of a long wave thermal infrared hyperspectral imager for measuring SO2 in volcanic plumes

NASA Astrophysics Data System (ADS)

Gabrieli, A.; Wright, R.; Porter, J. N.; Lucey, P. G.; Crites, S.; Garbeil, H.; Pilger, E. J.; Wood, M.

2015-12-01

The ability to quantify volcanic SO2 and image the spatial distribution in plumes either by day or by night would be beneficial to volcanologists. In this project, a newly developed remote sensing long-wave thermal infrared imaging hyperspectral sensor, was tested. The system employs a Sagnac interferometer and an uncooled microbolometer in rapid scanning configuration. This instrument is able to collect hyperspectral images of the scene between 8 and 14 and for each pixel a spectrum containing 50 samples can be retrieved. Images are spectrally and radiometrically calibrated using an IR source with a narrow band filter and two black bodies. The sensitivity of the system was studied by using a gas cell containing various known concentrations of SO2, which are representative of those found in volcanic plumes. Measured spectra were compared with theoretical spectra obtained from MODTRAN5 with the same viewing geometry and spectral resolution as the sensor. The MODTRAN5 calculations were carried out using a radiative transfer algorithm which accounts for the transmission and emission both inside and outside of the gas cell. These preliminary results and field measurements at Kīlauea volcano, Hawai'i will be discussed demonstrating the performance of the system and the ability of retrieving SO2 plume concentrations.

Design and experimental evaluation of a high temperature radial turbine with a moveable sidewall nozzle

NASA Technical Reports Server (NTRS)

Rogo, Casimir; Roelke, Richard J.

1987-01-01

The uncooled, 2.27 kg/sec mass flow radial turbine designed to operate at 1477 K in the gas generator of an advanced, variable-capacity 683 kW turboshaft engine was configured with a cooled, movable sidewall nozzle capable of changing the stage flow capacity from 50 to 100 percent of maximum. Overall performance test data were obtained in a turbine test rig that duplicated engine Reynolds numbers; attention is given to the changing of flow capacity by moving the hub or shroud sidewall, vane sidewall leakage, vaneless space sidewall geometry, and nozzle-cooling injection. Data are presented in the form of turbine flow, efficiency, work parameter, and performance mappings.

A Scalable Fabrication Process for Liquid Crystal Based Uncooled Thermal Imagers

DTIC Science & Technology

2016-02-12

ll.mit.edu). Phillip Bos, Valerie Finnemeyer, Colin McGinty and Douglas Bryant are with the Liquid Crystal Institute at Kent State University, Kent...Crystal-Based Uncooled Thermal Imagers Shaun Berry, Carl Bozler, Robert Reich, Harry Clark Jr., Phillip Bos, Valerie Finnemeyer, Colin McGinty...was aligned to the die features on the wafer with appropriate weight added (Fig. 5b). We used stainless steel bars to apply the weight to the block

Uncooled long-wave infrared hyperspectral imaging

NASA Technical Reports Server (NTRS)

Lucey, Paul G. (Inventor)

2006-01-01

A long-wave infrared hyperspectral sensor device employs a combination of an interferometer with an uncooled microbolometer array camera to produce hyperspectral images without the use of bulky, power-hungry motorized components, making it suitable for UAV vehicles, small mobile platforms, or in extraterrestrial environments. The sensor device can provide signal-to-noise ratios near 200 for ambient temperature scenes with 33 wavenumber resolution at a frame rate of 50 Hz, with higher results indicated by ongoing component improvements.

Kinetics of Hydrogen Oxidation Downstream of Lean Propane and Hydrogen Flames

NASA Technical Reports Server (NTRS)

Fine, Burton

1961-01-01

The decay of hydrogen was measured downstream of lean, flat, premixed hydrogen and propane-air flames seated on cooled porous burners. Experimental variables included temperature, pressure, initial equivalence ratio and diluent. Sampling of burned gas was done through uncooled quartz orifice probes, and the analysis was based on gas chromatography. An approximate treatment of the data in which diffusion was neglected led to the following rate expression for the zone downstream of hydrogen flames d[H (sub 2)] divided by (d times t) equals 1.7 times 10 (sup 10) [H (sub 2)] (sup 3) divided by (sub 2) [O (sub 2)]e (sup (-8100 divided by RT)) moles per liters per second. On the basis of a rate expression of this form, the specific rate constant for the reaction downstream of hydrogen flames was about three times as great as that determined downstream of propane flames. This result was explained on the basis of the existence of a steady state between hydrogen and carbon monoxide in the burned gas downstream of propane flames.

Uncooled detectors optimized for unattended applications

NASA Astrophysics Data System (ADS)

Malkinson, E.; Fraenkel, A.; Mizrahi, U.; Ben-Ezra, M.; Bikov, L.; Adin, A.; Zabar, Y.; Seter, D.; Kopolovich, Z.

2005-10-01

SCD has recently presented an uncooled detector product line based on the high-end VOx bolometer technology. The first FPA launched, named BIRD - short for Bolometer Infra Red Detector, is a 384x288 (or 320x240) configurable format with 25μm pitch. Typical NETD values for these FPAs range at 50mK with an F/1 aperture and 60 Hz frame rate. These detectors also exhibit a relatively fast thermal time constant of approximately 10 msec, as reported previously. In this paper, the special features of BIRD optimized for unattended sensor applications are presented and discussed. Unattended surveillance using sensors on unattended aerial vehicles (UAV's) or micro air vehicles (MAV's) , unattended ground vehicles (UGV's) or unattended ground sensor (UGS) are growing applications for uncooled detectors. This is due to their low power consumption, low weight, negligible acoustic noise and reduced price. On the other hand, uncooled detectors are vulnerable to ambient drift. Even minor temperature fluctuations are manifested as fixed pattern noise (FPN). As a result, frequent, shutter operation must be applied, with the risk of blocking the scenery in critical time frames and loosing information for various scenarios. In order to increase the time span between shutter operations, SCD has incorporated various features within the FPA and supporting algorithms. This paper will discuss these features and present some illustrative examples. Minimum power consumption is another critical issue for unattended applications. SCD has addressed this topic by introducing the "Power Save" concept. For very low power applications or for TEC-less (Thermo-Electric-Cooler) applications, the flexible dilution architecture enables the system to operate the detector at a number of formats. This, together with a smooth frame rate and format transition capability turns SCD's uncooled detector to be well suited for unattended applications. These issues will be described in detail as well.

Risk of Neurological Insult in Competitive Deep Breath-Hold Diving.

PubMed

Tetzlaff, Kay; Schöppenthau, Holger; Schipke, Jochen D

2017-02-01

It has been widely believed that tissue nitrogen uptake from the lungs during breath-hold diving would be insufficient to cause decompression stress in humans. With competitive free diving, however, diving depths have been ever increasing over the past decades. A case is presented of a competitive free-diving athlete who suffered stroke-like symptoms after surfacing from his last dive of a series of 3 deep breath-hold dives. A literature and Web search was performed to screen for similar cases of subjects with serious neurological symptoms after deep breath-hold dives. A previously healthy 31-y-old athlete experienced right-sided motor weakness and difficulty speaking immediately after surfacing from a breathhold dive to a depth of 100 m. He had performed 2 preceding breath-hold dives to that depth with surface intervals of only 15 min. The presentation of symptoms and neuroimaging findings supported a clinical diagnosis of stroke. Three more cases of neurological insults were retrieved by literature and Web search; in all cases the athletes presented with stroke-like symptoms after single breath-hold dives of depths exceeding 100 m. Two of these cases only had a short delay to recompression treatment and completely recovered from the insult. This report highlights the possibility of neurological insult, eg, stroke, due to cerebral arterial gas embolism as a consequence of decompression stress after deep breath-hold dives. Thus, stroke as a clinical presentation of cerebral arterial gas embolism should be considered another risk of extreme breath-hold diving.

The 2-MM Range Receiving Module for Observations of Atmospheric Ozone Emission Line at 142.2 GHz

NASA Astrophysics Data System (ADS)

Piddyachiy, V. I.; Korolev, O. M.; Myshenko, V. V.; Shulga, V. M.

2015-09-01

A low-noise uncooled receiver was designed and constructed for measurements of the atmospheric ozone spectral line at 142.2 GHz. The design has shown the double-sideband (DSB) receiver noise temperature of about 350 K within 130 to 150 GHz. Critical construction features of the basic units (mixer, intermediate frequency amplifier, and diplexer) are described. Noise characteristics showed by the receiver are the best in the class of uncooled heterodyne receivers of the 2-mm wavelengths.

Experimental Results of Ground Disturbance Detection Using Uncooled Infrared Imagers in Wideband and Multispectral Modes

DTIC Science & Technology

2012-02-01

and undisturbed soil. An uncooled IR imager with sufficient sensitivity ( Noise equivalent of temperature difference or NETD) at around 100mK NETD...Imager temperature sensitivity in bandpass mode: NETD is defined as the temperature difference ( T) for which the signal-to- noise ratio (SNR) equals to...1 where the signal is proportional to radiance L (watt/cm2-ster) while noise level is known. The NETD of the imager, however, will degrade when it

Unmanned Ground Vehicle Perception Using Thermal Infrared Cameras

NASA Technical Reports Server (NTRS)

Rankin, Arturo; Huertas, Andres; Matthies, Larry; Bajracharya, Max; Assad, Christopher; Brennan, Shane; Bellut, Paolo; Sherwin, Gary

2011-01-01

TIR cameras can be used for day/night Unmanned Ground Vehicle (UGV) autonomous navigation when stealth is required. The quality of uncooled TIR cameras has significantly improved over the last decade, making them a viable option at low speed Limiting factors for stereo ranging with uncooled LWIR cameras are image blur and low texture scenes TIR perception capabilities JPL has explored includes: (1) single and dual band TIR terrain classification (2) obstacle detection (pedestrian, vehicle, tree trunks, ditches, and water) (3) perception thru obscurants

Innovative on-chip packaging applied to uncooled IRFPA

NASA Astrophysics Data System (ADS)

Dumont, Geoffroy; Arnaud, Agnès; Impérinetti, Pierre; Vialle, Claire; Rabaud, Wilfried; Goudon, Valérie; Yon, Jean-Jacques

2008-04-01

The Laboratoire Infrarouge (LIR) of the Laboratoire d'Electronique et de Technologie de l'Information (LETI) has been involved in the development of microbolometers for over fifteen years. Two generations of technology have been transferred to ULIS and LETI is still working to improve performances of low cost detectors. Simultaneously, packaging still represents a significant part of detectors price. Reducing production costs would contribute to keep on extending applications of uncooled IRFPA to high volume markets like automotive. Therefore LETI is developing an on-chip packaging technology dedicated to microbolometers. This paper presents an original microcap structure that enables the use of IR window materials as sealing layers to maintain the expected vacuum level. The modelling and integration of an IR window suitable for this structure is also presented. This monolithic packaging technology is performed in a standard collective way, in continuation of bolometers' technology. The CEA-LETI, MINATEC presents status of these developments concerning this innovating technology including optical simulations results and SEM views of technical realizations.

Implementation of real-time nonuniformity correction with multiple NUC tables using FPGA in an uncooled imaging system

NASA Astrophysics Data System (ADS)

Oh, Gyong Jin; Kim, Lyang-June; Sheen, Sue-Ho; Koo, Gyou-Phyo; Jin, Sang-Hun; Yeo, Bo-Yeon; Lee, Jong-Ho

2009-05-01

This paper presents a real time implementation of Non Uniformity Correction (NUC). Two point correction and one point correction with shutter were carried out in an uncooled imaging system which will be applied to a missile application. To design a small, light weight and high speed imaging system for a missile system, SoPC (System On a Programmable Chip) which comprises of FPGA and soft core (Micro-blaze) was used. Real time NUC and generation of control signals are implemented using FPGA. Also, three different NUC tables were made to make the operating time shorter and to reduce the power consumption in a large range of environment temperature. The imaging system consists of optics and four electronics boards which are detector interface board, Analog to Digital converter board, Detector signal generation board and Power supply board. To evaluate the imaging system, NETD was measured. The NETD was less than 160mK in three different environment temperatures.

Evaluation of Microbolometer-Based Thermography for Gossamer Space Structures

NASA Technical Reports Server (NTRS)

Miles, Jonathan J.; Blandino, Joseph R.; Jenkins, Christopher H.; Pappa, Richard S.; Banik, Jeremy; Brown, Hunter; McEvoy, Kiley

2005-01-01

In August 2003, NASA's In-Space Propulsion Program contracted with our team to develop a prototype on-board Optical Diagnostics System (ODS) for solar sail flight tests. The ODS is intended to monitor sail deployment as well as structural and thermal behavior, and to validate computational models for use in designing future solar sail missions. This paper focuses on the thermography aspects of the ODS. A thermal model was developed to predict local sail temperature variations as a function of sail tilt to the sun, billow depth, and spectral optical properties of front and back sail surfaces. Temperature variations as small as 0.5 C can induce significant thermal strains that compare in magnitude to mechanical strains. These thermally induced strains may result in changes in shape and dynamics. The model also gave insight into the range and sensitivity required for in-flight thermal measurements and supported the development of an ABAQUS-coupled thermo-structural model. The paper also discusses three kinds of tests conducted to 1) determine the optical properties of candidate materials; 2) evaluate uncooled microbolometer-type infrared imagers; and 3) operate a prototype imager with the ODS baseline configuration. (Uncooled bolometers are less sensitive than cooled ones, but may be necessary because of restrictive ODS mass and power limits.) The team measured the spectral properties of several coated polymer samples at various angles of incidence. Two commercially available uncooled microbolometer imagers were compared, and it was found that reliable temperature measurements are feasible for both coated and uncoated sides of typical sail membrane materials.

Uncooled infrared photodetectors in Poland

NASA Astrophysics Data System (ADS)

Piotrowski, Jozef; Piotrowski, Adam

2005-09-01

The history and present status of the middle and long wavelength Hg1xCdxTe infrared detectors in Poland are reviewed. Research and development efforts in Poland were concentrated mostly on uncooled market niche. Technology of the infrared photodetectors has been developed by several research groups. The devices are based on mercury-based variable band gap semiconductor alloys. Modified isothermal vapor phase epitaxy (ISOVPE) has been used for many years for research and commercial fabrication of photoconductive, photoelectromagnetic and other devices. Bulk growth and liquid phase epitaxy was also used. At present, the fabrication of IR devices relies on low temperature epitaxial technique, namely metalorganic vapor phase deposition (MOCVD), frequently in combination with the ISOVPE. Photoconductive and photoelectromagnetic detectors are still in production. The devices are gradually replaced with photovoltaic devices which offer inherent advantages of no electric or magnetic bias, no heat load and no flicker noise. Potentially, the PV devices could offer high performance and very fast response. Actually, the uncooled long wavelength devices of conventional design suffer from two issues; namely low quantum efficiency and very low junction resistance. It makes them useless for practical applications. The problems have been solved with advanced 3D band gap engineered architecture, multiple cell heterojunction devices connected in series, monolithic integration of the detectors with microoptics and other improvements. Present fabrication program includes devices which are optimized for operation at any wavelength within a wide spectral range 1-15 μm and 200-300 K temperature range. Special solutions have been applied to improve speed of response. Some devices show picoseconds range response time. The devices have found numerous civilian and military applications.

Internal combustion engine with compressed air collection system

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

Brown, P.W.

1988-08-23

This patent describes an internal combustion engine comprising cylinders respectively including a pressure port, pistons respectively movable in the cylinders through respective compression strokes, fuel injectors respectively connected to the cylinders and operative to supply, from a fuel source to the respective cylinders, a metered quantity of fuel conveyed by compressed gas in response to fuel injector operation during the compression strokes of the respective cylinders, a storage tank for accumulating and storing compressed gas, means for selectively connecting the pressure ports to the storage tank only during the compression strokes of the respective cylinders, and duct means connecting themore » storage tank to the fuel injectors for supplying the fuel injectors with compressed gas in response to fuel injector operation.« less

Shutterless solution for simultaneous focal plane array temperature estimation and nonuniformity correction in uncooled long-wave infrared camera.

PubMed

Cao, Yanpeng; Tisse, Christel-Loic

2013-09-01

In uncooled long-wave infrared (LWIR) microbolometer imaging systems, temperature fluctuations of the focal plane array (FPA) result in thermal drift and spatial nonuniformity. In this paper, we present a novel approach based on single-image processing to simultaneously estimate temperature variances of FPAs and compensate the resulting temperature-dependent nonuniformity. Through well-controlled thermal calibrations, empirical behavioral models are derived to characterize the relationship between the responses of microbolometer and FPA temperature variations. Then, under the assumption that strong dependency exists between spatially adjacent pixels, we estimate the optimal FPA temperature so as to minimize the global intensity variance across the entire thermal infrared image. We make use of the estimated FPA temperature to infer an appropriate nonuniformity correction (NUC) profile. The performance and robustness of the proposed temperature-adaptive NUC method are evaluated on realistic IR images obtained by a 640 × 512 pixels uncooled LWIR microbolometer imaging system operating in a significantly changed temperature environment.

Liquid crystal uncooled thermal imager development

NASA Astrophysics Data System (ADS)

Clark, H. R.; Bozler, C. O.; Berry, S. R.; Reich, R. K.; Bos, P. J.; Finnemeyer, V. A.; Bryant, D. R.; McGinty, C.

2016-09-01

An uncooled thermal imager is being developed based on a liquid crystal (LC) transducer. Without any electrical connections, the LC transducer pixels change the long-wavelength infrared (LWIR) scene directly into a visible image as opposed to an electric signal in microbolometers. The objectives are to develop an imager technology scalable to large formats (tens of megapixels) while maintaining or improving the noise equivalent temperature difference (NETD) compared to microbolometers. The present work is demonstrating that the LCs have the required performance (sensitivity, dynamic range, speed, etc.) to enable a more flexible uncooled imager. Utilizing 200-mm wafers, a process has been developed and arrays have been fabricated using aligned LCs confined in 20×20-μm cavities elevated on thermal legs. Detectors have been successfully fabricated on both silicon and fused silica wafers using less than 10 photolithographic mask steps. A breadboard camera system has been assembled to test the imagers. Various sensor configurations are described along with advantages and disadvantages of component arrangements.

Metabolic cost of over ground gait in younger stroke patients and healthy controls.

PubMed

Platts, Marina M; Rafferty, Daniel; Paul, Lorna

2006-06-01

Locomotor impairment, such as that which may occur following a stroke, results in increased energy expenditure during walking. Previous research quantifying this increased metabolic demand has focused on older people; thus, the aim of this study was to investigate the physiological cost of walking in younger patients following stroke. Thirteen stroke patients (mean age of 40.7+/-10.0 yr) and 13 age- and sex-matched controls participated. Each subject walked for 5 min around an elliptical course (two cones set 9.5 m apart) at their own preferred walking speed (PWS). The percentage of expired oxygen was measured using a portable gas analyzer. Following a 5-min rest, the control subjects repeated the procedure, but at the PWS of the patient to whom they were matched. The PWS of the stroke patients was significantly lower than that of the controls (P<0.001); however, there was no significant difference in terms of oxygen uptake (P=0.403). When the distance walked was considered, there was a statistically significant difference in oxygen uptake per unit of distance between the two groups (P<0.001) and also between the patients PWS and the controls walking at the PWS of the patients. The high metabolic cost of walking would suggest that, even for younger stroke patients, early rehabilitation should consider aerobic evaluation and training with the aim of optimizing functional independence.

Study of atmospheric plasma spray process with the emphasis on gas-shrouded nozzles

NASA Astrophysics Data System (ADS)

Jankovic, Miodrag M.

An atmospheric plasma spraying process is investigated in this work by using experimental approach and mathematical modelling. Emphasis was put on the gas shrouded nozzles, their design, and the protection against the mixing with the surrounding air, which they give to the plasma jet. First part of the thesis is dedicated to the analysis of enthalpy probe method, as a major diagnostic tool in this work. Systematic error in measuring the stagnation pressure, due to a big temperature difference between the plasma and the water-cooled probe, is investigated here. Parallel measurements with the enthalpy probe and an uncooled ceramic probe were performed. Also, numerical experiments were conducted, using the k-ɛ model of turbulence. Based on the obtained results, a compensating algorithm for the above error is suggested. Major objective of the thesis was to study the plasma spraying process, and potential benefits from using the gas shrouded nozzles. Mathematical modelling was used to perform the parametric study on the flow pattern inside these nozzles. Two nozzles were used: a commercial conical nozzle, and a custom-made curvilinear nozzle. The later is aimed towards elimination of the cold air entrainment, recorded for the conical nozzle. Also, parametric study on the shrouding gas and its interaction with the plasma jet was carried out. Two modes of the shrouding gas injection were tested: through sixteen injection ports, and through a continuous slot, surrounding the plasma jet. Both nozzles and both injection modes were thoroughly tested, experimentally and numerically. The curvilinear nozzle completely eliminates the cold air entrainment and yields significantly higher plasma temperature. Also, injection through the continuous slot resulted in a much better protection of the plasma jet. Both nozzles were used to perform the spraying tests. Obtained coatings were tested on porosity, adhesion strength, and micro- structure. These tests indicated better micro-structure of the coatings sprayed by the curvilinear nozzle. Also, their porosity was significantly lower, and the adhesion strength was higher for more than 25%. The overall results suggest that the curvilinear nozzles represent a much better solution for the gas shrouded plasma spraying.

An investigation of improved airbag performance by vent control and gas injection

NASA Astrophysics Data System (ADS)

Lee, Calvin; Rosato, Nick; Lai, Francis

Airbags are currently being investigated as an impact energy absorber for U.S. Army airdrop. Simple airbags with constant vent areas have been found to be unsatisfactory in yielding high G forces. In this paper, a method of controlling the vent area and a method of injecting gas into the airbag during its compression stroke to improve airbag performance are presented. Theoretical analysis of complex airbags using these two methods show that they provide lower G forces than simple airbags. Vertical drop tests of a vent-control airbag confirm this result. Gas-injection airbags are currently being tested.

The changes on physical characteristics of lightning discharge plasma during individual return stroke process

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

Xu, He; Yuan, Ping; Cen, Jian-Yong

2014-03-15

A cloud-to-ground lightning with six return strokes has been recorded with a slit-less spectrograph in Qinghai province. According to the spectra of return strokes without continuous current, the electron density, the channel temperature, and the gas pressure have been calculated. Then, the correlativity of these parameters has been analyzed. The results indicate that the total intensity of spectra is positive correlated to the intensity of spectral line, they both decrease with time rapidly; furthermore, the channel temperature and the gas pressure decrease with time slowly in the similar trends.

Low-cost uncooled VOx infrared camera development

NASA Astrophysics Data System (ADS)

Li, Chuan; Han, C. J.; Skidmore, George D.; Cook, Grady; Kubala, Kenny; Bates, Robert; Temple, Dorota; Lannon, John; Hilton, Allan; Glukh, Konstantin; Hardy, Busbee

2013-06-01

The DRS Tamarisk® 320 camera, introduced in 2011, is a low cost commercial camera based on the 17 µm pixel pitch 320×240 VOx microbolometer technology. A higher resolution 17 µm pixel pitch 640×480 Tamarisk®640 has also been developed and is now in production serving the commercial markets. Recently, under the DARPA sponsored Low Cost Thermal Imager-Manufacturing (LCTI-M) program and internal project, DRS is leading a team of industrial experts from FiveFocal, RTI International and MEMSCAP to develop a small form factor uncooled infrared camera for the military and commercial markets. The objective of the DARPA LCTI-M program is to develop a low SWaP camera (<3.5 cm3 in volume and <500 mW in power consumption) that costs less than US $500 based on a 10,000 units per month production rate. To meet this challenge, DRS is developing several innovative technologies including a small pixel pitch 640×512 VOx uncooled detector, an advanced digital ROIC and low power miniature camera electronics. In addition, DRS and its partners are developing innovative manufacturing processes to reduce production cycle time and costs including wafer scale optic and vacuum packaging manufacturing and a 3-dimensional integrated camera assembly. This paper provides an overview of the DRS Tamarisk® project and LCTI-M related uncooled technology development activities. Highlights of recent progress and challenges will also be discussed. It should be noted that BAE Systems and Raytheon Vision Systems are also participants of the DARPA LCTI-M program.

Emissions from in-use lawn-mowers in Australia

NASA Astrophysics Data System (ADS)

Priest, M. W.; Williams, D. J.; Bridgman, H. A.

Concern over the levels of pollutants emitted from small engines has led to recent legislation in the United States that regulates exhaust emissions from lawn and garden equipment. Particular attention has focused on the high levels of hydrocarbons emitted by these engines. The present study establishes emission factors for lawn-mowers in use in Australia. The estimates were calculated on the basis of a series of controlled emission tests conducted on commonly used lawn-mowers. Ten two-stroke and six four-stroke lawn-mower engines were operated under simulated power requirements while fuel usage and gas emissions were monitored. Fuel consumption rates from the tests were compared to those ascertained under actual mowing conditions in field tests conducted on 19 two-stroke and ten four-stroke lawn-mowers. Basic emission factors were established for CO, CO 2, CH 4, NMHC and NO x, and combined with data on machine population and annual usage collected in a survey of lawn care practices and lawn-mower usage conducted in the Newcastle area. When compared to transport sources in the Newcastle study region, lawn-mowers contribute 5.2 and 11.6% of CO and NMHC emissions, respectively.

Uncooled infrared photodetectors in Poland

NASA Astrophysics Data System (ADS)

Piotrowski, J.; Piotrowski, A.

2006-03-01

The history and present status of the middle and long wavelength Hg1-xCdxTe infrared detectors in Poland are reviewed. Research and development efforts in Poland were concentrated mostly on uncooled market niche. Technology of the infrared photodetectors has been developed by several research groups. The devices are based on mercury-based variable band gap semiconductor alloys. Modified isothermal vapour phase epitaxy (ISOVPE) has been used for many years for research and commercial fabrication of photoconductive, photoelectromagnetic and other devices. Bulk growth and liquid phase epitaxy was also used. At present, the fabrication of IR devices relies on low temperature epitaxial technique, namely metalorganic vapour phase deposition (MOCVD), frequently in combination with the ISOVPE. Photoconductive and photoelectromagnetic detectors are still in production. The devices are gradually replaced with photovoltaic devices which offer inherent advantages of no electric or magnetic bias, no heat load and no flicker noise. Potentially, the PV devices could offer high performance and very fast response. At present, the uncooled long wavelength devices of conventional design suffer from two issues; namely low quantum efficiency and very low junction resistance. It makes them useless for practical applications. The problems have been solved with advanced 3D band gap engineered architecture, multiple cell heterojunction devices connected in series, monolithic integration of the detectors with microoptics and other improvements. Present fabrication program includes devices which are optimized for operation at any wavelength within a wide spectral range 1-15 μm and 200-300 K temperature range. Special solutions have been applied to improve speed of response. Some devices show picoseconds range response time. The devices have found numerous civilian and military applications.

Modulate chopper technique used in pyroelectric uncooled focal plane array thermal imager

NASA Astrophysics Data System (ADS)

He, Yuqing; Jin, Weiqi; Liu, Guangrong; Gao, Zhiyun; Wang, Xia; Wang, Lingxue

2002-09-01

Pyroelectric uncooled focal plane array (FPA) thermal imager has the advantages of low cost, small size, high responsibility and can work under room temperature, so it has great progress in recent years. As a matched technique, the modulate chopper has become one of the key techniques in uncooled FPA thermal imaging system. Now the Archimedes spiral cord chopper technique is mostly used. When it works, the chopper pushing scans the detector's pixel array, thus makes the pixels being exposed continuously. This paper simulates the shape of this kind of chopper, analyses the exposure time of the detector's every pixel, and also analyses the whole detector pixels' exposure sequence. From the analysis we can get the results: the parameter of Archimedes spiral cord, the detector's thermal time constant, the detector's geometrical dimension, the relative position of the detector to the chopper's spiral cord are the system's important parameters, they will affect the chopper's exposure efficiency and uniformity. We should design the chopper's relevant parameter according to the practical request to achieve the chopper's appropriate structure.

Uncooled thermal imaging and image analysis

NASA Astrophysics Data System (ADS)

Wang, Shiyun; Chang, Benkang; Yu, Chunyu; Zhang, Junju; Sun, Lianjun

2006-09-01

Thermal imager can transfer difference of temperature to difference of electric signal level, so can be application to medical treatment such as estimation of blood flow speed and vessel 1ocation [1], assess pain [2] and so on. With the technology of un-cooled focal plane array (UFPA) is grown up more and more, some simple medical function can be completed with un-cooled thermal imager, for example, quick warning for fever heat with SARS. It is required that performance of imaging is stabilization and spatial and temperature resolution is high enough. In all performance parameters, noise equivalent temperature difference (NETD) is often used as the criterion of universal performance. 320 x 240 α-Si micro-bolometer UFPA has been applied widely presently for its steady performance and sensitive responsibility. In this paper, NETD of UFPA and the relation between NETD and temperature are researched. several vital parameters that can affect NETD are listed and an universal formula is presented. Last, the images from the kind of thermal imager are analyzed based on the purpose of detection persons with fever heat. An applied thermal image intensification method is introduced.

Analytical Modelling of the Effects of Different Gas Turbine Cooling Techniques on Engine Performance =

NASA Astrophysics Data System (ADS)

Uysal, Selcuk Can

In this research, MATLAB SimulinkRTM was used to develop a cooled engine model for industrial gas turbines and aero-engines. The model consists of uncooled on-design, mean-line turbomachinery design and a cooled off-design analysis in order to evaluate the engine performance parameters by using operating conditions, polytropic efficiencies, material information and cooling system details. The cooling analysis algorithm involves a 2nd law analysis to calculate losses from the cooling technique applied. The model is used in a sensitivity analysis that evaluates the impacts of variations in metal Biot number, thermal barrier coating Biot number, film cooling effectiveness, internal cooling effectiveness and maximum allowable blade temperature on main engine performance parameters of aero and industrial gas turbine engines. The model is subsequently used to analyze the relative performance impact of employing Anti-Vortex Film Cooling holes (AVH) by means of data obtained for these holes by Detached Eddy Simulation-CFD Techniques that are valid for engine-like turbulence intensity conditions. Cooled blade configurations with AVH and other different external cooling techniques were used in a performance comparison study. (Abstract shortened by ProQuest.).

Uncooled Infrared Microbolometers and Silicon Germanium Oxide (SixGe1-xOy) Infrared Sensitive Material for Long Wavelength Detection

DTIC Science & Technology

2014-10-10

Hooge ’s parameters and 1/f noise at the comer frequency for the four wafers are shown in Table 6. We see in the table that the average value of ywas...voltage noise power spectral densities were analyzed and Hooge’s parameters were determined. UNCOOLED MICROBOLOMETER A thermal detector exhibits a...annealing at 200 °C, 250 °C, and 300 °C for duration from 1 hour to 5 hours using a bias current of 0.07 µA. The corresponding Hooge’s parameters for

Thermal hyperspectral chemical imaging

NASA Astrophysics Data System (ADS)

Holma, Hannu; Hyvärinen, Timo; Mattila, Antti-Jussi; Kormano, Ilkka

2012-06-01

Several chemical compounds have their strongest spectral signatures in the thermal region. This paper presents three push-broom thermal hyperspectral imagers. The first operates in MWIR (2.8-5 μm) with 35 nm spectral resolution. It consists of uncooled imaging spectrograph and cryogenically cooled InSb camera, with spatial resolution of 320/640 pixels and image rate to 400 Hz. The second imager covers LWIR in 7.6-12 μm with 32 spectral bands. It employs an uncooled microbolometer array and spectrograph. These imagers have been designed for chemical mapping in reflection mode in industry and laboratory. An efficient line-illumination source has been developed, and it makes possible thermal hyperspectral imaging in reflection with much higher signal and SNR than is obtained from room temperature emission. Application demonstrations including sorting of dark plastics and mineralogical mapping of drill cores are presented. The third imager utilizes a cryo-cooled MCT array with precisely temperature stabilized optics. The optics is not cooled, but instrument radiation is suppressed by special filtering and corrected by BMC (Background-Monitoring-on-Chip) method. The approach provides excellent sensitivity in an instrument which is portable and compact enough for installation in UAVs. The imager has been verified in 7.6 to 12.3 μm to provide NESR of 18 mW/(m2 sr μm) at 10 μm for 300 K target with 100 spectral bands and 384 spatial samples. It results in SNR of higher than 500. The performance makes possible various applications from gas detection to mineral exploration and vegetation surveys. Results from outdoor and airborne experiments are shown.

Wrapping cytochrome c around single-wall carbon nanotube: engineered nanohybrid building blocks for infrared detection at high quantum efficiency

PubMed Central

Gong, Youpin; Liu, Qingfeng; Wilt, Jamie Samantha; Gong, Maogang; Ren, Shenqiang; Wu, Judy

2015-01-01

Biomolecule cytochrome c (Cty c), a small molecule of a chain of amino acids with extraordinary electron transport, was helically wrapped around a semiconductive single-wall carbon nanotube (s-SWCNT) to form a molecular building block for uncooled infrared detection with two uniquely designed functionalities: exciton dissociation to free charge carriers at the heterojunction formed on the s-SWCNT/Cty c interface and charge transport along the electron conducting chain of Cty c (acceptor) and hole conducting channel through s-SWCNT (donor). Such a design aims at addressing the long-standing challenges in exciton dissociation and charge transport in an SWCNT network, which have bottlenecked development of photonic SWCNT-based infrared detectors. Using these building blocks, uncooled s-SWCNT/Cyt c thin film infrared detectors were synthesized and shown to have extraordinary photoresponsivity up to 0.77 A W−1 due to a high external quantum efficiency (EQE) in exceeding 90%, which represents a more than two orders of magnitude enhancement than the best previously reported on CNT-based infrared detectors with EQE of only 1.72%. From a broad perspective, this work on novel s-SWCNT/Cyt c nanohybrid infrared detectors has developed a successful platform of engineered carbon nanotube/biomolecule building blocks with superior properties for optoelectronic applications. PMID:26066737

Wrapping cytochrome c around single-wall carbon nanotube: engineered nanohybrid building blocks for infrared detection at high quantum efficiency.

PubMed

Gong, Youpin; Liu, Qingfeng; Wilt, Jamie Samantha; Gong, Maogang; Ren, Shenqiang; Wu, Judy

2015-06-11

Biomolecule cytochrome c (Cty c), a small molecule of a chain of amino acids with extraordinary electron transport, was helically wrapped around a semiconductive single-wall carbon nanotube (s-SWCNT) to form a molecular building block for uncooled infrared detection with two uniquely designed functionalities: exciton dissociation to free charge carriers at the heterojunction formed on the s-SWCNT/Cty c interface and charge transport along the electron conducting chain of Cty c (acceptor) and hole conducting channel through s-SWCNT (donor). Such a design aims at addressing the long-standing challenges in exciton dissociation and charge transport in an SWCNT network, which have bottlenecked development of photonic SWCNT-based infrared detectors. Using these building blocks, uncooled s-SWCNT/Cyt c thin film infrared detectors were synthesized and shown to have extraordinary photoresponsivity up to 0.77 A W(-1) due to a high external quantum efficiency (EQE) in exceeding 90%, which represents a more than two orders of magnitude enhancement than the best previously reported on CNT-based infrared detectors with EQE of only 1.72%. From a broad perspective, this work on novel s-SWCNT/Cyt c nanohybrid infrared detectors has developed a successful platform of engineered carbon nanotube/biomolecule building blocks with superior properties for optoelectronic applications.

TOPICAL REVIEW: GaN-based diodes and transistors for chemical, gas, biological and pressure sensing

NASA Astrophysics Data System (ADS)

Pearton, S. J.; Kang, B. S.; Kim, Suku; Ren, F.; Gila, B. P.; Abernathy, C. R.; Lin, Jenshan; Chu, S. N. G.

2004-07-01

There is renewed emphasis on development of robust solid-state sensors capable of uncooled operation in harsh environments. The sensors should be capable of detecting chemical, gas, biological or radiation releases as well as sending signals to central monitoring locations. We discuss the advances in use of GaN-based solid-state sensors for these applications. AlGaN/GaN high electron mobility transistors (HEMTs) show a strong dependence of source/drain current on the piezoelectric polarization-induced two-dimensional electron gas (2DEG). Furthermore, spontaneous and piezoelectric polarization-induced surface and interface charges can be used to develop very sensitive but robust sensors to detect gases, polar liquids and mechanical pressure. AlGaN/GaN HEMT structures have been demonstrated to exhibit large changes in source-drain current upon exposing the gate region to various block co-polymer solutions. Pt-gated GaN Schottky diodes and Sc2O3/AlGaN/GaN metal-oxide semiconductor diodes also show large change in forward currents upon exposure to H2. Of particular interest is detection of ethylene (C2H4), which has strong double bonds and hence is difficult to dissociate at modest temperatures. Apart from combustion gas sensing, the AlGaN/GaN heterostructure devices can be used as sensitive detectors of pressure changes. In addition, large changes in source-drain current of the AlGaN/GaN HEMT sensors can be detected upon adsorption of biological species on the semiconductor surface. Finally, the nitrides provide an ideal platform for fabrication of surface acoustic wave (SAW) devices. The GaN-based devices thus appear promising for a wide range of chemical, biological, combustion gas, polar liquid, strain and high temperature pressure-sensing applications. In addition, the sensors are compatible with high bit-rate wireless communication systems that facilitate their use in remote arrays.

Hydrogen gas improves left ventricular hypertrophy in Dahl rat of salt-sensitive hypertension.

PubMed

Matsuoka, Hiroki; Miyata, Seiko; Okumura, Nozomi; Watanabe, Takuya; Hashimoto, Katsunori; Nagahara, Miki; Kato, Kazuko; Sobue, Sayaka; Takeda, Kozue; Ichihara, Masatoshi; Iwamoto, Takashi; Noda, Akiko

2018-06-14

Hypertension is an important risk factor for death resulting from stroke, myocardial infarction, and end-stage renal failure. Hydrogen (H 2 ) gas protects against many diseases, including ischemia-reperfusion injury and stroke. The effects of H 2 on hypertension and its related left ventricular (LV) function have not been fully elucidated. The purpose of this study was to investigate the effects of H 2 gas on hypertension and LV hypertrophy using echocardiography. Dahl salt-sensitive (DS) rats were randomly divided into three groups: those fed an 8% NaCl diet until 12 weeks of age (8% NaCl group), those additionally treated with H 2 gas (8% NaCl + H 2 group), and control rats maintained on a diet containing 0.3% NaCl until 12 weeks of age (0.3% NaCl group). H 2 gas was supplied through a gas flowmeter and delivered by room air (2% hydrogenated room air, flow rate of 10 L/min) into a cage surrounded by an acrylic chamber. We evaluated interventricular septal wall thickness (IVST), LV posterior wall thickness (LVPWT), and LV mass using echocardiography. IVST, LVPWT, and LV mass were significantly higher in the 8% NaCl group than the 0.3% NaCl group at 12 weeks of age, whereas they were significantly lower in the 8% NaCl + H 2 group than the 8% NaCl group. There was no significant difference in systolic blood pressure between the two groups. Our findings suggest that chronic H 2 gas inhalation may help prevent LV hypertrophy in hypertensive DS rats.

THERMAP : a mid-infrared spectro-imager for the Marco Polo R mission

NASA Astrophysics Data System (ADS)

Groussin, O.; Brageot, E.; Reynaud, J.-L.; Lamy, P.; Jorda, L.; Licandro, J.; Helbert, J.; Knollenberg, J.; Kührt, E.; Delbó, M.

2012-09-01

We present THERMAP, a mid-infrared (8-16 μm) spectro-imager based on uncooled micro-bolometer detector arrays. Due to the recent technological development of these detectors, which have undergone significant improvements in the last decade, we wanted to test their performances for a space mission to small bodies in the inner Solar System. THERMAP was selected by ESA in January 2012 for a one year assessment study, in the framework of a call for declaration of interest in science instrumentation for the Marco Polo R Cosmic Vision mission. In this paper, we present some results of this study and in particular demonstrate that the new generation of uncooled micro-bolometer detectors has all the imaging and spectroscopic capabilities to fulfill the scientific objectives of the Marco Polo R mission. THERMAP scientific objectives - The midinfrared instrument of the Marco Polo R mission must be able i) to determine the surface temperature by mapping the entire surface with an absolute accuracy of at least 5 K (goal 1 K) above 200 K, ii) to determine the thermal inertia with an accuracy of 10% and iii) to determine the surface composition by mapping the entire surface with a spectral resolution of 70 between 8 and 16 μm. The above mappings should be performed with a spatial resolution of 10 m for the entire surface (global characterization) and 10 cm for the sampling sites (local characterization). THERMAP imaging capabilities - In order to test the imaging capabilities of the THERMAP uncooled microbolometer detector, we set up an experiment based on a 640x480 ULIS micro-bolometer array, a germanium objective and a black body. Using the results of this experiment, we show that calibrated radiometric images can be obtained down to at least 258 K (lower limit of our experiment), and that two calibration points are sufficient to determine the absolute scene temperature with an accuracy better than 1.5 K. An extrapolation to lower temperatures provides an accuracy of about 5 K at 180 K, the lowest temperature the detector can measure. THERMAP spectroscopic capabilites - In order to test the spectroscopic performances of the detector, we added flux attenuating neutral density mid-infrared filters (transmittance: 50%, 10%, 1%) to our experiment. Our results show that we can perform spectroscopic measurements with a spectral resolution R=40-80 in the wavelength range 8-16 μm for a scene temperature larger than 300 K, the typical surface temperature of a Near Earth Asteroid at 1 AU from the Sun. THERMAP preliminary design - From the above results, we defined a preliminary design for the instrument. THERMAP is a mid-infrared (8-16 μm) spectro-imager based on two uncooled microbolometer arrays. It is composed of two channels, one for imaging and one for spectroscopy. A flip mirror allows switching between the two channels. Calibration is performed using deep space and two black bodies at known temperature. The design of the THERMAP instrument has a strong heritage from the MERTIS instrument on board Bepi-Colombo [1], which guarantees its feasibility and reliability. Our design is very flexible in term of operations, which is fundamental for a mission to a binary asteroid system (1996 FG3). The THERMAP instrument will be proposed for Marco Polo R and any future space missions to small bodies in the inner solar system.

High Ethanol Fuel Endurance: A Study of the Effects of Running Gasoline with 15% Ethanol Concentration in Current Production Outboard Four-Stroke Engines and Conventional Two-Stroke Outboard Marine Engines

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

Hilbert, D.

2011-10-01

Three Mercury Marine outboard marine engines were evaluated for durability using E15 fuel -- gasoline blended with 15% ethanol. Direct comparison was made to operation on E0 (ethanol-free gasoline) to determine the effects of increased ethanol on engine durability. Testing was conducted using a 300-hour wide-open throttle (WOT) test protocol, a typical durability cycle used by the outboard marine industry. Use of E15 resulted in reduced CO emissions, as expected for open-loop, non-feedback control engines. HC emissions effects were variable. Exhaust gas and engine operating temperatures increased as a consequence of leaner operation. Each E15 test engine exhibited some deteriorationmore » that may have been related to the test fuel. The 9.9 HP, four-stroke E15 engine exhibited variable hydrocarbon emissions at 300 hours -- an indication of lean misfire. The 300HP, four-stroke, supercharged Verado engine and the 200HP, two-stroke legacy engine tested with E15 fuel failed to complete the durability test. The Verado engine failed three exhaust valves at 285 endurance hours while the 200HP legacy engine failed a main crank bearing at 256 endurance hours. All E0-dedicated engines completed the durability cycle without incident. Additional testing is necessary to link the observed engine failures to ethanol in the test fuel.« less

Real-time analysis of aromatics in combustion engine exhaust by resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOF-MS): a robust tool for chassis dynamometer testing.

PubMed

Adam, T W; Clairotte, M; Streibel, T; Elsasser, M; Pommeres, A; Manfredi, U; Carriero, M; Martini, G; Sklorz, M; Krasenbrink, A; Astorga, C; Zimmermann, R

2012-07-01

Resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOF-MS) is a robust method for real-time analysis of monocyclic and polycyclic aromatic hydrocarbons in complex emissions. A mobile system has been developed which enables direct analysis on site. In this paper, we utilize a multicomponent calibration scheme based on the analytes' photo-ionisation cross-sections relative to a calibrated species. This allows semi-quantification of a great number of components by only calibrating one compound of choice, here toluene. The cross-sections were determined by injecting nebulised solutions of aromatic compounds into the TOF-MS ion source with the help of a HPLC pump. Then, REMPI-TOF-MS was implemented at various chassis dynamometers and test cells and the exhaust of the following vehicles and engines investigated: a compression ignition light-duty (LD) passenger car, a compression ignition LD van, two spark ignition LD passenger cars, 2 two-stroke mopeds, and a two-stroke engine of a string gas trimmer. The quantitative time profiles of benzene are shown. The results indicate that two-stroke engines are a significant source for toxic and cancerogenic compounds. Air pollution and health effects caused by gardening equipment might still be underestimated.

A review on applications of magnetoelectric composites: from heterostructural uncooled magnetic sensors, energy harvesters to highly efficient power converters

NASA Astrophysics Data System (ADS)

Leung, Chung Ming; Li, Jiefang; Viehland, D.; Zhuang, X.

2018-07-01

Over the past two decades, magnetoelectric (ME) composites and their devices have been an important topic of research. Potential applications ranging from low-power sensing to high-power converters have been investigated. This review, first begins with a summary of multiferroic materials that work at room temperature. Such ME materials are usually in composites, and their ME effect generated as a product property of magnetostrictive and piezoelectric composite layers. After that, mechanisms, working principles, and applications of ME composites from heterostructural uncooled magnetic sensors, energy harvesters to highly efficient power converters will be discussed. First, the development of ME sensors in terms of materials and structures to enhance their sensitivities and to reduce noise level is reviewed and discussed. Second, the structure of ME-based energy harvesters is discussed and summarized. Third, the development of ME gyrators is summarized for power applications, including current/voltage conversion, power efficiency, power density and figures of merit. Results demonstrate that our ME gyrator has the ability to satisfy the needs of power conversion with superior efficiency (>90%), offering potential uses in power electronic applications.

Strategic Defense Initiative Program: Extent of Foreign Participation

DTIC Science & Technology

1990-02-07

the Air Force to a West German company, . Chemical Lasers project, for fabrication of a lightweight hig mirror . The firished product will be a 70...centimeter mirror lightweight, uncool"P glass ceramic material with no tus.rm. Two contracts, totaling $1.7 million, were au-arded under th Definition...Ground-Based Free The ground-based laser system concept is to fire a free electrru Electron Laser Project beam generated on the ground to a mirror relay

Innovative on-chip packaging applied to uncooled IRFPA

NASA Astrophysics Data System (ADS)

Dumont, Geoffroy; Arnaud, Agnès; Imperinetti, Pierre; Mottin, Eric; Simoens, François; Vialle, Claire; Rabaud, Wilfried; Grand, Gilles; Baclet, Nathalie

2008-03-01

The Laboratoire Infrarouge (LIR) of the Laboratoire d'Electronique et de Technologie de l'Information (LETI) has been involved in the development of microbolometers for over fifteen years. Two generations of technology have been transferred to ULIS and LETI is still working to improve performances of low cost detectors. Simultaneously, packaging still represents a significant part of detectors price. Reducing production costs would contribute to keep on extending applications of uncooled IRFPA to high volume markets like automotive. Therefore LETI develops an onchip packaging technology dedicated to microbolometers. The efficiency of a micropackaging technology for microbolometers relies on two major technical specifications. First, it must include an optical window with a high transmittance for the IR band, so as to maximize the detector absorption. Secondly, in order to preserve the thermal insulation of the detector, the micropackaging must be hermetically closed to maintain a vacuum level lower than 10 -3mbar. This paper presents an original microcap structure that enables the use of IR window materials as sealing layers to maintain the expected vacuum level. The modelling and integration of an IR window suitable for this structure is also presented. This zero level packaging technology is performed in a standard collective way, in continuation of bolometers' technology. The CEA-LETI, MINATEC presents status of these developments concerning this innovating technology including optical simulations results and SEM views of technical realizations.

MWIR hyperspectral imaging with the MIDAS instrument

NASA Astrophysics Data System (ADS)

Honniball, Casey I.; Wright, Rob; Lucey, Paul G.

2017-02-01

Hyperspectral imaging (HSI) in the Mid-Wave InfraRed (MWIR, 3-5 microns) can provide information on a variety of science applications from determining the chemical composition of lava lakes on Jupiter's moon Io, to investigating the amount of carbon liberated into the Earth's atmosphere during a wildfire. The limited signal available in the MWIR presents technical challenges to achieving high signal-to-noise ratios, and therefore it is typically necessary to cryogenically cool MWIR instruments. With recent improvements in microbolometer technology and emerging interferometric techniques, we have shown that uncooled microbolometers coupled with a Sagnac interferometer can achieve high signal-to-noise ratios for long-wave infrared HSI. To explore if this technique can be applied to the MWIR, this project, with funding from NASA, has built the Miniaturized Infrared Detector of Atmospheric Species (MIDAS). Standard characterization tests are used to compare MIDAS against a cryogenically cooled photon detector to evaluate the MIDAS instruments' ability to quantify gas concentrations. Atmospheric radiative transfer codes are in development to explore the limitations of MIDAS and identify the range of science objectives that MIDAS will most likely excel at. We will simulate science applications with gas cells filled with varying gas concentrations and varying source temperatures to verify our results from lab characterization and our atmospheric modeling code.

Low-cost directionally-solidified turbine blades, volume 2. [TFE731-3 turbofan engine

NASA Technical Reports Server (NTRS)

Dennis, R. E.; Hoppin, G. S., III; Hurst, L. G.

1979-01-01

An endothermically heated technology was used to manufacture low cost, directionally solidified, uncooled nickel-alloy blades for the TFE731-3 turbofan engine. The MAR-M 247 and MER-M 100+Hf blades were finish processed through heat treatment, machining, and coating operations prior to 150 hour engine tests consisting of the following sequences: (1) 50 hours of simulated cruise cycling (high fatigue evaluation); (2) 50 hours at the maximum continuous power rating (stress rupture endurance (low cycle fatigue). None of the blades visually showed any detrimental effects from the test. This was verified by post test metallurgical evaluation. The specific fuel consumption was reduced by 2.4% with the uncooled blades.

Uncooled infrared imaging using bimaterial microcantilever arrays

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

Grbovic, Dragoslav; Lavrik, Nickolay V; Rajic, Slobodan

2006-01-01

We report on the fabrication and characterization of microcantilever based uncooled focal plane array (FPA) for infrared imaging. By combining a streamlined design of microcantilever thermal transducers with a highly efficient optical readout, we minimized the fabrication complexity while achieving a competitive level of imaging performance. The microcantilever FPAs were fabricated using a straightforward fabrication process that involved only three photolithographic steps (i.e. three masks). A designed and constructed prototype of an IR imager employed a simple optical readout based on a noncoherent low-power light source. The main figures of merit of the IR imager were found to be comparablemore » to those of uncooled MEMS infrared detectors with substantially higher degree of fabrication complexity. In particular, the NETD and the response time of the implemented MEMS IR detector were measured to be as low as 0.5K and 6 ms, respectively. The potential of the implemented designs can also be concluded from the fact that the constructed prototype enabled IR imaging of close to room temperature objects without the use of any advanced data processing. The most unique and practically valuable feature of the implemented FPAs, however, is their scalability to high resolution formats, such as 2000x2000, without progressively growing device complexity and cost.« less

An Approach to the Prototyping of an Optimized Limited Stroke Actuator to Drive a Low Pressure Exhaust Gas Recirculation Valve

PubMed Central

Gutfrind, Christophe; Dufour, Laurent; Liebart, Vincent; Vannier, Jean-Claude; Vidal, Pierre

2016-01-01

The purpose of this article is to describe the design of a limited stroke actuator and the corresponding prototype to drive a Low Pressure (LP) Exhaust Gas Recirculation (EGR) valve for use in Internal Combustion Engines (ICEs). The direct drive actuator topology is an axial flux machine with two air gaps in order to minimize the rotor inertia and a bipolar surface-mounted permanent magnet in order to respect an 80° angular stroke. Firstly, the actuator will be described and optimized under constraints of a 150 ms time response, a 0.363 N·m minimal torque on an angular range from 0° to 80° and prototyping constraints. Secondly, the finite element method (FEM) using the FLUX-3D® software (CEDRAT, Meylan, France) will be used to check the actuator performances with consideration of the nonlinear effect of the iron material. Thirdly, a prototype will be made and characterized to compare its measurement results with the analytical model and the FEM model results. With these electromechanical behavior measurements, a numerical model is created with Simulink® in order to simulate an EGR system with this direct drive actuator under all operating conditions. Last but not least, the energy consumption of this machine will be estimated to evaluate the efficiency of the proposed EGR electromechanical system. PMID:27213398

An Approach to the Prototyping of an Optimized Limited Stroke Actuator to Drive a Low Pressure Exhaust Gas Recirculation Valve.

PubMed

Gutfrind, Christophe; Dufour, Laurent; Liebart, Vincent; Vannier, Jean-Claude; Vidal, Pierre

2016-05-20

The purpose of this article is to describe the design of a limited stroke actuator and the corresponding prototype to drive a Low Pressure (LP) Exhaust Gas Recirculation (EGR) valve for use in Internal Combustion Engines (ICEs). The direct drive actuator topology is an axial flux machine with two air gaps in order to minimize the rotor inertia and a bipolar surface-mounted permanent magnet in order to respect an 80° angular stroke. Firstly, the actuator will be described and optimized under constraints of a 150 ms time response, a 0.363 N·m minimal torque on an angular range from 0° to 80° and prototyping constraints. Secondly, the finite element method (FEM) using the FLUX-3D(®) software (CEDRAT, Meylan, France) will be used to check the actuator performances with consideration of the nonlinear effect of the iron material. Thirdly, a prototype will be made and characterized to compare its measurement results with the analytical model and the FEM model results. With these electromechanical behavior measurements, a numerical model is created with Simulink(®) in order to simulate an EGR system with this direct drive actuator under all operating conditions. Last but not least, the energy consumption of this machine will be estimated to evaluate the efficiency of the proposed EGR electromechanical system.

Uncooled Micro-Cantilever Infrared Imager Optimization

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

Panagiotis, Datskos G.

2008-02-05

We report on the development, fabrication and characterization of microcantilever based uncooled focal plane array (FPA) for infrared imaging. By combining a streamlined design of microcantilever thermal transducers with a highly efficient optical readout, we minimized the fabrication complexity while achieving a competitive level of imaging performance. The microcantilever FPAs were fabricated using a straightforward fabrication process that involved only three photolithographic steps (i.e. three masks). A designed and constructed prototype of an IR imager employed a simple optical readout based on a noncoherent low-power light source. The main figures of merit of the IR imager were found to bemore » comparable to those of uncooled MEMS infrared detectors with substantially higher degree of fabrication complexity. In particular, the NETD and the response time of the implemented MEMS IR detector were measured to be as low as 0.5K and 6 ms, respectively. The potential of the implemented designs can also be concluded from the fact that the constructed prototype enabled IR imaging of close to room temperature objects without the use of any advanced data processing. The most unique and practically valuable feature of the implemented FPAs, however, is their scalability to high resolution formats, such as 2000 x 2000, without progressively growing device complexity and cost. The overall technical objective of the proposed work was to develop uncooled infrared arrays based on micromechanical sensors. Currently used miniature sensors use a number of different readout techniques to accomplish the sensing. The use of optical readout techniques sensing require the deposition of thin coatings on the surface of micromechanical thermal detectors. Oak Ridge National Laboratory (ORNL) is uniquely qualified to perform the required research and development (R&D) services that will assist our ongoing activities. Over the past decade ORNL has developed a number of unique methods and techniques that led to improved sensors using a number of different approaches.« less

Generation of strong terahertz fields exceeding 8 MV/cm at 1 kHz and real-time beam profiling

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

Oh, T. I.; Yoo, Y. J.; You, Y. S.

2014-07-28

We demonstrate high-field (>8 MV/cm) terahertz generation at a high-repetition-rate (1 kHz) via two-color laser filamentation. Here, we use a cryogenically cooled femtosecond laser amplifier capable of producing 30 fs, 15 mJ pulses at 1 kHz as a driver, along with a combination of a thin dual-wavelength half-waveplate and a Brewster-angled silicon window to enhance terahertz generation and transmission. We also introduce a cost-effective, uncooled microbolometer camera for real-time terahertz beam profiling with two different modes.

Cloud Optical Depth Measured with Ground-Based, Uncooled Infrared Imagers

NASA Technical Reports Server (NTRS)

Shaw, Joseph A.; Nugent, Paul W.; Pust, Nathan J.; Redman, Brian J.; Piazzolla, Sabino

2012-01-01

Recent advances in uncooled, low-cost, long-wave infrared imagers provide excellent opportunities for remotely deployed ground-based remote sensing systems. However, the use of these imagers in demanding atmospheric sensing applications requires that careful attention be paid to characterizing and calibrating the system. We have developed and are using several versions of the ground-based "Infrared Cloud Imager (ICI)" instrument to measure spatial and temporal statistics of clouds and cloud optical depth or attenuation for both climate research and Earth-space optical communications path characterization. In this paper we summarize the ICI instruments and calibration methodology, then show ICI-derived cloud optical depths that are validated using a dual-polarization cloud lidar system for thin clouds (optical depth of approximately 4 or less).

Operating characteristics of a hydrogen-argon plasma torch for supersonic combustion applications

NASA Technical Reports Server (NTRS)

Barbi, E.; Mahan, J. R.; O'Brien, W. F.; Wagner, T. C.

1989-01-01

The residence time of the combustible mixture in the combustion chamber of a scramjet engine is much less than the time normally required for complete combustion. Hydrogen and hydrocarbon fuels require an ignition source under conditions typically found in a scramjet combustor. Analytical studies indicate that the presence of hydrogen atoms should greatly reduce the ignition delay in this environment. Because hydrogen plasmas are prolific sources of hydrogen atoms, a low-power, uncooled hydrogen plasma torch has been built and tested to evaluate its potential as a possible flame holder for supersonic combustion. The torch was found to be unstable when operated on pure hydrogen; however, stable operation could be obtained by using argon as a body gas and mixing in the desired amount of hydrogen. The stability limits of the torch are delineated and its electrical and thermal behavior documented. An average torch thermal efficiency of around 88 percent is demonstrated.

A LWIR hyperspectral imager using a Sagnac interferometer and cooled HgCdTe detector array

NASA Astrophysics Data System (ADS)

Lucey, Paul G.; Wood, Mark; Crites, Sarah T.; Akagi, Jason

2012-06-01

LWIR hyperspectral imaging has a wide range of civil and military applications with its ability to sense chemical compositions at standoff ranges. Most recent implementations of this technology use spectrographs employing varying degrees of cryogenic cooling to reduce sensor self-emission that can severely limit sensitivity. We have taken an interferometric approach that promises to reduce the need for cooling while preserving high resolution. Reduced cooling has multiple benefits including faster system readiness from a power off state, lower mass, and potentially lower cost owing to lower system complexity. We coupled an uncooled Sagnac interferometer with a 256x320 mercury cadmium telluride array with an 11 micron cutoff to produce a spatial interferometric LWIR hyperspectral imaging system operating from 7.5 to 11 microns. The sensor was tested in ground-ground applications, and from a small aircraft producing spectral imagery including detection of gas emission from high vapor pressure liquids.

Two-stroke engine diagnostics and design

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

Not Available

1992-01-01

This paper focuses on research and development efforts on two-stroke cycle engines for automotive applications. Partial contents include: Velocity Field Characteristics in Motored Two-Stroke Ported Engines; Flow Vector Measurements at the Scavenging Ports in a Fired Two-Stroke Engine; A Study on Exhaust Dynamic Effect of Two-Stroke Motorcycle Petrol Engine; Characterization of Ignition and Parametric Study of a Two-Stroke-Cycle Direct-Injected Gasoline Engine; LDV Measurements of Intake Port Flow in a Two-Stroke Engine with and without Combustion; Appraisal of Regenerative Blowers for Scavenging of Small 2T S.I. Powerplants; and Development Experience of a Poppet-Valved Two-Stroke Flagship Engine.

Cerebral arterial gas embolism from attempted mechanical thrombectomy: recovery following hyperbaric oxygen therapy.

PubMed

Segan, Louise; Permezel, Fiona; Ch'ng, Wei; Millar, Ian; Brooks, Mark; Lee-Archer, Matt; Cloud, Geoffrey

2018-04-01

Cerebral arterial gas embolism is a recognised complication of endovascular intervention with an estimated incidence of 0.08%. Its diagnosis is predominantly clinical, supported by neuroimaging. The treatment relies on alleviating mechanical obstruction and reversing the proinflammatory processes that contribute to tissue ischaemia. Hyperbaric oxygen therapy is an effective treatment and has multiple mechanisms to reverse the pathological processes involved in cerebral arterial gas embolism. Symptomatic cerebral arterial gas embolism is a rare complication of endovascular intervention for acute ischaemic stroke. Although there are no previous descriptions of its successful treatment with hyperbaric oxygen therapy following mechanical thrombectomy, this is likely to become more common as mechanical thrombectomy is increasingly used worldwide to treat acute ischaemic stroke. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Challenges, constraints, and results of lens design for 17 micron-bolometer focal plane arrays in 8-12 micron waveband

NASA Astrophysics Data System (ADS)

Schuster, Norbert; Franks, John

2011-06-01

In the 8-12 micron waveband Focal Plane Arrays (FPA) are available with a 17 micron pixel pitch in different arrays sizes (e.g. 512 x 480 pixels and 320 x 240 pixels) and with excellent electrical properties. Many applications become possible using this new type of IR-detector which will become the future standard in uncooled technology. Lenses with an f-number faster than f/1.5 minimize the diffraction impact on the spatial resolution and guarantee a high thermal resolution for uncooled cameras. Both effects will be quantified. The distinction between Traditional f-number (TF) and Radiometric f-number (RF) is discussed. Lenses with different focal lengths are required for applications in a variety of markets. They are classified by their Horizontal field of view (HFOV). Respecting the requirements for high volume markets, several two lens solutions will be discussed. A commonly accepted parameter of spatial resolution is the Modulation Transfer Function (MTF)-value at the Nyquist frequency of the detector (here 30cy/mm). This parameter of resolution will be presented versus field of view. Wide Angle and Super Wide Angle lenses are susceptible to low relative illumination in the corner of the detector. Measures to reduce this drop to an acceptable value are presented.

High-speed uncooled MWIR hostile fire indication sensor

NASA Astrophysics Data System (ADS)

Zhang, L.; Pantuso, F. P.; Jin, G.; Mazurenko, A.; Erdtmann, M.; Radhakrishnan, S.; Salerno, J.

2011-06-01

Hostile fire indication (HFI) systems require high-resolution sensor operation at extremely high speeds to capture hostile fire events, including rocket-propelled grenades, anti-aircraft artillery, heavy machine guns, anti-tank guided missiles and small arms. HFI must also be conducted in a waveband with large available signal and low background clutter, in particular the mid-wavelength infrared (MWIR). The shortcoming of current HFI sensors in the MWIR is the bandwidth of the sensor is not sufficient to achieve the required frame rate at the high sensor resolution. Furthermore, current HFI sensors require cryogenic cooling that contributes to size, weight, and power (SWAP) in aircraft-mounted applications where these factors are at a premium. Based on its uncooled photomechanical infrared imaging technology, Agiltron has developed a low-SWAP, high-speed MWIR HFI sensor that breaks the bandwidth bottleneck typical of current infrared sensors. This accomplishment is made possible by using a commercial-off-the-shelf, high-performance visible imager as the readout integrated circuit and physically separating this visible imager from the MWIR-optimized photomechanical sensor chip. With this approach, we have achieved high-resolution operation of our MWIR HFI sensor at 1000 fps, which is unprecedented for an uncooled infrared sensor. We have field tested our MWIR HFI sensor for detecting all hostile fire events mentioned above at several test ranges under a wide range of environmental conditions. The field testing results will be presented.

Thermal Loss Determination for a Small Internal Combustion Engine

DTIC Science & Technology

2014-03-27

calibration temperature rc Compression ratio S̄ p Mean piston speed T Temperature Vc Combustion chamber volume Vd Displacement volume Wc,i Indicated work...are typically fueled by gasoline, ignited by a spark, and operate on either a two or four-stroke cycle. Compression-ignition diesel engines as seen in...engine, the fuel is usually withheld from the cylinder until the combustion event is desired as in diesel engines. Similarly, the fuel in a gas

LWIR NUC using an uncooled microbolometer camera

NASA Astrophysics Data System (ADS)

Laveigne, Joe; Franks, Greg; Sparkman, Kevin; Prewarski, Marcus; Nehring, Brian; McHugh, Steve

2010-04-01

Performing a good non-uniformity correction is a key part of achieving optimal performance from an infrared scene projector. Ideally, NUC will be performed in the same band in which the scene projector will be used. Cooled, large format MWIR cameras are readily available and have been successfully used to perform NUC, however, cooled large format LWIR cameras are not as common and are prohibitively expensive. Large format uncooled cameras are far more available and affordable, but present a range of challenges in practical use for performing NUC on an IRSP. Santa Barbara Infrared, Inc. reports progress on a continuing development program to use a microbolometer camera to perform LWIR NUC on an IRSP. Camera instability and temporal response and thermal resolution are the main difficulties. A discussion of processes developed to mitigate these issues follows.

Life satisfaction post stroke: The role of illness cognitions.

PubMed

van Mierlo, M L; van Heugten, C M; Post, Mwm; de Kort, Plm; Visser-Meily, Jma

2015-08-01

To describe illness cognitions two months and two years post stroke and to investigate changes in illness cognitions over time. We also examined the associations between illness cognitions and life satisfaction at two months and two years post stroke and investigated if changes in illness cognitions predicted life satisfaction two years post stroke, taking demographic and stroke-related factors and emotional symptoms into account. Prospective cohort study in which 287 patients were assessed at two months and two years post stroke. The illness cognitions helplessness (maladaptive), acceptance (adaptive) and perceiving benefits (adaptive) were measured with the Illness Cognition Questionnaire. Life satisfaction was assessed with two life satisfaction questions. Correlational and regression analyses were performed. Patients experienced both maladaptive and adaptive illness cognitions two months and two years post stroke. Only acceptance increased significantly from two months to two years post stroke (p≤0.01). Helplessness, acceptance and perceiving benefits were significantly associated with life satisfaction at two months (R2=0.42) and two years (R2=0.57) post stroke. Furthermore, illness cognitions two months post stroke and changes in illness cognitions predicted life satisfaction two years post stroke (R2=0.57). Illness cognitions and changes in illness cognitions were independently associated with life satisfaction two years post stroke. It is therefore important during rehabilitation to focus on reducing maladaptive behavior and feelings to promote life satisfaction, and on promoting adaptive illness cognitions. Copyright © 2015 Elsevier Inc. All rights reserved.

Probing Cosmic Gas Accretion with RESOLVE and ECO

NASA Astrophysics Data System (ADS)

Kannappan, Sheila; Eckert, Kathleen D.; Stark, David; Lagos, Claudia; Nasipak, Zachary; Moffett, Amanda J.; Baker, Ashley; Berlind, Andreas A.; Hoversten, Erik A.; Norris, Mark A.; RESOLVE Team

2016-01-01

We review results bearing on the existence, controlling factors, and mechanisms of cosmic gas accretion in the RESOLVE and ECO surveys. Volume-limited analysis of RESOLVE's complete census of HI-to-stellar mass ratios and star formation histories for ~1500 galaxies points to the necessity of an "open box" model of galaxy fueling, with the most gas-dominated galaxies doubling their stellar masses on ~Gyr timescales in a regime of rapid accretion. Transitions in gas richness and disk-building activity for isolated or central galaxies with halo masses near ~10^11.5 Msun and ~10^12 Msun plausibly correspond to the endpoints of a theoretically predicted transition in halo gas temperature that slows accretion across this range. The same mass range is associated with the initial grouping of isolated galaxies into common halos, where "isolated" is defined relative to the survey baryonic mass limits of >~10^9 Msun. Above 10^11.5 Msun, patterns in central vs. satellite gas richness as a function of group halo mass suggest that galaxy refueling is valved off from the inside out as the halo grows, with total quenching beyond the virial radius for halo masses >~10^13-13.5 Msun. Within the transition range from ~10^11.5-10^12 Msun, theoretical models predict >3 dex dispersion in ratios of uncooled halo gas to cold gas in galaxies (or more generally gas and stars). In RESOLVE and ECO, the baryonic mass function of galaxies in this transitional halo mass range displays signs of stripping or destruction of satellites, leading us to investigate a possible connection with halo gas heating using central galaxy color and group dynamics to probe group evolutionary state. Finally, we take a first look at how internal variations in metallicity, dynamics, and star formation constrain accretion mechanisms such as cold streams, induced extraplanar gas cooling, isotropic halo gas cooling, and gas-rich merging in different mass and environment regimes. The RESOLVE and ECO surveys have been supported by funding from NSF grants AST-0955368 and OCI-1156614.

Concept Doped-Silicon Thermopile Detectors for Future Planetary Thermal Imaging Instruments

NASA Astrophysics Data System (ADS)

Lakew, Brook; Barrentine, Emily M.; Aslam, Shahid; Brown, Ari D.

2016-10-01

Presently, uncooled thermopiles are the detectors of choice for thermal mapping in the 4.6-100 μm spectral range. Although cooled detectors like Ge or Si thermistor bolometers, and MgB2 or YBCO superconducting bolometers, have much higher sensitivity, the required active or passive cooling mechanisms add prohibitive cost and mass for long duration missions. Other uncooled detectors, likepyroelectrics, require a motor mechanism to chop against a known reference temperature, which adds unnecessary mission risk. Uncooled vanadium oxide or amorphous Si microbolometer arrays with integrated CMOS readout circuits, not only have lower sensitivity, but also have not been proven to be radiation hard >100 krad (Si) total ionizing dose, and barring additional materials and readout development, their performance has reached a plateau.Uncooled and radiation hard thermopiles with D* ~1x109 cm√Hz/W and time constant τ ~100 ms have been integrated into thermal imaging instruments on several past missions and have extensive flight heritage (Mariner, Voyager, Cassini, LRO, MRO). Thermopile arrays are also on the MERTIS instrument payload on-board the soon to be launched BepiColombo Mission.To date, thermopiles used for spaceflight instrumentation have consisted of either hand assembled "one-off" single thermopile pixels or COTS thermopile pixel arrays both using Bi-Sb or Bi-Te thermoelectric materials. For future high performance imagers, thermal detector arrays with higher D*, lower τ, and high efficiency delineated absorbers are desirable. Existing COTS and other flight thermopile designs require highly specialized and nonstandard processing techniques to fabricate both the Bi-Sb or Bi-Te thermocouples and the gold or silver black absorbers, which put limitations on further development.Our detector arrays will have a D* ≥ 3x109 cm√Hz/W and a thermal time constant ≤ 30 ms at 170 K. They will be produced using proven, standard semiconductor and MEMS fabrication techniques, which will enable the future integration of other ancillary structures like high efficiency broadband absorbers, which will result in D* ≥ 5x109 cm√Hz/W.

A Thermal Imaging Instrument with Uncooled Detectors

NASA Astrophysics Data System (ADS)

Joseph, A. T.; Barrentine, E. M.; Brown, A. D.

2017-12-01

In this work, we perform an instrument concept study for sustainable thermal imaging over land with uncooled detectors. The National Research Council's Committee on Implementation of a Sustained Land Imaging Program has identified the inclusion of a thermal imager as critical for both current and future land imaging missions. Such an imaging instrument operating in two bands located at approximately 11 and 12 microns (for example, in Landsat 8, and also Landsat 9 when launched) will provide essential information for furthering our hydrologic understanding at scales of human influence, and produce field-scale moisture information through accurate retrievals of evapotranspiration (ET). Landsat 9 is slated to recycle the TIRS-2 instrument launched with Landsat 8 that uses cooled quantum well infrared photodetectors (QWIPs), hence requiring expensive and massive cryocooler technology to achieve its required spectral and spatial accuracies. Our goal is to conceptualize and develop a thermal imaging instrument which leverages recent and imminent technology advances in uncooled detectors. Such detector technology will offer the benefit of greatly reduced instrument cost, mass, and power at the expense of some acceptable loss in detector sensitivity. It would also allow a thermal imaging instrument to be fielded on board a low-cost platform, e.g., a CubeSat. Sustained and enhanced land imaging is crucial for providing high-quality science data on change in land use, forest health, crop status, environment, and climate. Accurate satellite mapping of ET at the agricultural field scale (the finest spatial scale of the environmental processes of interest) requires high-quality thermal data to produce the corresponding accurate land surface temperature (LST) retrievals used to drive an ET model. Such an imaging instrument would provide important information on the following: 1) the relationship between land-use and land/water management practices and water use dynamics; 2) the interconnections between anthropogenic water management and changes in hydrologic budget at scales of human influence; and 3) complimentary field-scale moisture values for interpreting coarser resolution datasets. There is a clear need for continuing innovation in thermal remote sensing detector technology.

The MIDAS Instrument Design and Characterization

NASA Astrophysics Data System (ADS)

Honniball, C. I.; Wright, R.; Lucey, P. G.

2016-10-01

The Miniaturized Infrared detector of Atmospheric Species (MIDAS) utilizes an uncooled microbolometer coupled with a Sagnac interferometer. MIDAS will be used to detect and quantify atmospheric constituents for a variety of science applications.

Mid-infrared two-photon absorption in an extended-wavelength InGaAs photodetector

NASA Astrophysics Data System (ADS)

Piccardo, Marco; Rubin, Noah A.; Meadowcroft, Lauren; Chevalier, Paul; Yuan, Henry; Kimchi, Joseph; Capasso, Federico

2018-01-01

We investigate the nonlinear optical response of a commercial extended-wavelength In0.81Ga0.19As uncooled photodetector. Degenerate two-photon absorption in the mid-infrared range is observed using a quantum cascade laser emitting at λ = 4.5 μm as the excitation source. From the measured two-photon photocurrent signal, we extract a two-photon absorption coefficient β(2) = 0.6 ± 0.2 cm/MW, in agreement with the theoretical value obtained from the Eg-3 scaling law. Considering the wide spectral range covered by extended-wavelength InxGa1-xAs alloys, this result holds promise for applications based on two-photon absorption for this family of materials at wavelengths between 1.8 and 5.6 μm.

Fabrication of a 20.5-inch-diameter segmented silicon annular optic prototype for the ROMA program

NASA Astrophysics Data System (ADS)

Hassell, Frank R.; Groark, Frank M.

1995-10-01

Recent advancements in single crystal silicon material science and fabrication capabilities and very low absorption (VLA) multi-layer dielectric coating technology have led to the development of uncooled, large aperture, high power mirrors for high energy laser (HEL) systems. Based on this success, a segmented single-crystal silicon substrate concept has been selected as the baseline fabrication approach for uncooled 1.2 meter diameter resonator annular optics for the Alpha space based high energy laser. The objective of this Resonator Optics Materials Assessment (ROMA) task was to demonstrate all of the key fabrication processes required to fabricate the full sized annular optics for the Alpha space based high energy laser. This paper documents the fabrication of a half-scale annular optic prototype (AOP) of the Alpha laser rear cone.

Uncooled pump combiners for fiber laser and amplifier systems

NASA Astrophysics Data System (ADS)

Bansal, L.; Sienkowski, R.; Neale, C.; Mann, J.; Headley, C.

2018-02-01

In this work we demonstrate a high transmission pump combiner that can operate uncooled at a maximum power of 400W for a continuous duration of 100hrs. The 7x1 pump combiner has seven 105/125 μm diameter 0.22 NA input pump fibers and a 247 μm diameter and 0.22 NA glass clad output fiber. The combiner has a high, 99%, pump transmission efficiency. These devices withstand without failure, a series of environmental stress tests, namely Thermal Cycling (-40 to 85ºC) and Damp Humidity (85ºC/85RH). These tests are conducted to uncover any latent defects in the device structure. The combiner's also survive an elevated temperature of 75ºC at a power of 365W for duration of 5hrs, without any noticeable change in pump transmission.

Characterization and initial field test of an 8-14 μm thermal infrared hyperspectral imager for measuring SO2 in volcanic plumes

NASA Astrophysics Data System (ADS)

Gabrieli, Andrea; Wright, Robert; Lucey, Paul G.; Porter, John N.; Garbeil, Harold; Pilger, Eric; Wood, Mark

2016-10-01

The ability to image and quantify SO2 path-concentrations in volcanic plumes, either by day or by night, is beneficial to volcanologists. Gas emission rates are affected by the chemical equilibria in rising magmas and a better understanding of this relationship would be useful for short-term eruption prediction. A newly developed remote sensing long-wave thermal InfraRed (IR) imaging hyperspectral sensor - the Thermal Hyperspectral Imager (THI) - was built and tested. The system employs a Sagnac interferometer and an uncooled microbolometer in rapid scanning configuration to collect hyperspectral images of volcanic plumes. Each pixel in the resulting image yields a spectrum with 50 samples between 8 and 14 μm. Images are spectrally and radiometrically calibrated using an IR source with a narrow band filter and two blackbodies. In this paper, the sensitivity of the instrument for the purpose of quantifying SO2 using well constrained laboratory experiments is evaluated, and initial field results from Kīlauea volcano, Hawai'i, are presented. The sensitivity of THI was determined using gas cells filled with known concentrations of SO2 and using NIST-traceable blackbodies to simulate a range of realistic background conditions. Measurements made by THI were then benchmarked against a high spectral resolution off-the-shelf Michelson FTIR instrument. Theoretical thermal IR spectral radiances were computed with MODTRAN5 for the same optical conditions, to evaluate how well the (known) concentration of SO2 in the gas cells could be retrieved from the resulting THI spectra. Finally, THI was recently field-tested at Kīlauea to evaluate its ability to image the concentration of SO2 in a real volcanic plume. A path-concentration of 7150 ppm m was retrieved from measurements made near the Halema'uma'u vent.

Use of COTS uncooled microbolometers for the observation of solar eruptions in far infrared

NASA Astrophysics Data System (ADS)

Le Ruyet, B.; Bernardi, P.; Sémery, A.

2017-11-01

The Small Explorer for Solar Eruptions (SMESE) mission is a French-Chinese satellite dedicated to the combined study of coronal mass ejections and flares. It should operate by the beginning of 2013. The spacecraft is based on a generic MYRIADE platform developed by CNES. Its payload consists of a Lyman α imager and a Lyman α chronograph (LYOT), a far infrared telescope (DESIR) and a hard X and γ ray spectrometer (HEBS). Its Sun-synchronous orbit will allow for continuous observations. LESIA (Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique, in Paris-Meudon Observatory) is in charge of DESIR instrument. DESIR (Detection of Eruptive Solar InfraRed emission) is an imaging photometer observing the sun in two bandwidths: [25; 45μm] and [80; 130μm]. The detector is a commercially available, uncooled microbolometer focal plane array (UL 02 05 1, from ULIS) designed for thermographic imaging in the 8-14 μm wavelength range. The 160x120 pixels are based on amorphous silicon, with dimensions 35x35 μm2. The performances in terms of noise and dynamics given by the manufacturer associated with simulations of a perfect quarter-wave cavity to predict the microbolometer absorption, make possible the use of such a detector to fulfil the DESIR detection specifications in the two FIR bandwidths. During the A Phase, tests have been carried out in our laboratory to validate the feasibility of the project. In this work, we present the first results obtained on the microbolometer performances in the FIR domain.

AGT (Advanced Gas Turbine) technology project

NASA Technical Reports Server (NTRS)

1988-01-01

An overall summary documentation is provided for the Advanced Gas Turbine Technology Project conducted by the Allison Gas Turbine Division of General Motors. This advanced, high risk work was initiated in October 1979 under charter from the U.S. Congress to promote an engine for transportation that would provide an alternate to reciprocating spark ignition (SI) engines for the U.S. automotive industry and simultaneously establish the feasibility of advanced ceramic materials for hot section components to be used in an automotive gas turbine. As this program evolved, dictates of available funding, Government charter, and technical developments caused program emphases to focus on the development and demonstration of the ceramic turbine hot section and away from the development of engine and powertrain technologies and subsequent vehicular demonstrations. Program technical performance concluded in June 1987. The AGT 100 program successfully achieved project objectives with significant technology advances. Specific AGT 100 program achievements are: (1) Ceramic component feasibility for use in gas turbine engines has been demonstrated; (2) A new, 100 hp engine was designed, fabricated, and tested for 572 hour at operating temperatures to 2200 F, uncooled; (3) Statistical design methodology has been applied and correlated to experimental data acquired from over 5500 hour of rig and engine testing; (4) Ceramic component processing capability has progressed from a rudimentary level able to fabricate simple parts to a sophisticated level able to provide complex geometries such as rotors and scrolls; (5) Required improvements for monolithic and composite ceramic gas turbine components to meet automotive reliability, performance, and cost goals have been identified; (6) The combustor design demonstrated lower emissions than 1986 Federal Standards on methanol, JP-5, and diesel fuel. Thus, the potential for meeting emission standards and multifuel capability has been initiated; (7) Small turbine engine aerodynamic and mechanical design capability has been initiated; and (8) An infrastructure of manpower, facilities, materials, and fabrication capabilities has been established which is available for continued development of ceramic component technology in gas turbine and other heat engines.

40 CFR 90.103 - Exhaust emission standards.

Code of Federal Regulations, 2010 CFR

2010-07-01

... incremental weight of a four stroke engine or the incremental weight of a two stroke engine having enhanced... of a four stroke or enhanced two stroke engine having the same, less or very similar power to two stroke engines that could otherwise be used to power the equipment and remain within the weight...

40 CFR 90.103 - Exhaust emission standards.

Code of Federal Regulations, 2013 CFR

2013-07-01

... incremental weight of a four stroke engine or the incremental weight of a two stroke engine having enhanced... of a four stroke or enhanced two stroke engine having the same, less or very similar power to two stroke engines that could otherwise be used to power the equipment and remain within the weight...

40 CFR 90.103 - Exhaust emission standards.

Code of Federal Regulations, 2014 CFR

2014-07-01

... incremental weight of a four stroke engine or the incremental weight of a two stroke engine having enhanced... of a four stroke or enhanced two stroke engine having the same, less or very similar power to two stroke engines that could otherwise be used to power the equipment and remain within the weight...

40 CFR 90.103 - Exhaust emission standards.

Code of Federal Regulations, 2011 CFR

2011-07-01

... incremental weight of a four stroke engine or the incremental weight of a two stroke engine having enhanced... of a four stroke or enhanced two stroke engine having the same, less or very similar power to two stroke engines that could otherwise be used to power the equipment and remain within the weight...

40 CFR 90.103 - Exhaust emission standards.

Code of Federal Regulations, 2012 CFR

2012-07-01

... incremental weight of a four stroke engine or the incremental weight of a two stroke engine having enhanced... of a four stroke or enhanced two stroke engine having the same, less or very similar power to two stroke engines that could otherwise be used to power the equipment and remain within the weight...

Diesel emission reduction using internal exhaust gas recirculation

DOEpatents

He, Xin [Denver, CO; Durrett, Russell P [Bloomfield Hills, MI

2012-01-24

A method for controlling combustion in a direct-injection diesel engine includes monitoring a crankshaft rotational position of a cylinder of the engine, monitoring an engine load, determining an intake stroke within the cylinder based upon the crankshaft rotational position, and when the engine load is less than a threshold engine load, opening an exhaust valve for the cylinder during a portion of the intake stroke.

Alternative general-aircraft engines

NASA Technical Reports Server (NTRS)

Tomazic, W. A.

1976-01-01

The most promising alternative engine (or engines) for application to general aircraft in the post-1985 time period was defined, and the level of technology was cited to the point where confident development of a new engine can begin early in the 1980's. Low emissions, multifuel capability, and fuel economy were emphasized. Six alternative propulsion concepts were considered to be viable candidates for future general-aircraft application: the advanced spark-ignition piston, rotary combustion, two- and four-stroke diesel, Stirling, and gas turbine engines.

Progress on uncooled PbSe detectors for low-cost applications

NASA Astrophysics Data System (ADS)

Vergara, German; Gomez, Luis J.; Villamayor, Victor; Alvarez, M.; Rodrigo, Maria T.; del Carmen Torquemada, Maria; Sanchez, Fernando J.; Verdu, Marina; Diezhandino, Jorge; Rodriguez, Purificacion; Catalan, Irene; Almazan, Rosa; Plaza, Julio; Montojo, Maria T.

2004-08-01

This work reports on progress on development of polycrystalline PbSe infrared detectors at the Centro de Investigacion y Desarrollo de la Armada (CIDA). Since mid nineties, the CIDA owns an innovative technology for processing uncooled MWIR detectors of polycrystalline PbSe. Based on this technology, some applications have been developed. However, future applications demand smarter, more complex, faster yet cheaper detectors. Aiming to open new perspectives to polycrystalline PbSe detectors, we are currently working on different directions: 1) Processing of 2D arrays: a) Designing and processing low density x-y addressed arrays with 16x16 and 32x32 elements, as an extension of our standard technology. b) Trying to make compatible standard CMOS and polycrystalline PbSe technologies in order to process monolithic large format arrays. 2) Adding new features to the detector such as monolithically integrated spectral discrimination.

Single-image-based solution for optics temperature-dependent nonuniformity correction in an uncooled long-wave infrared camera.

PubMed

Cao, Yanpeng; Tisse, Christel-Loic

2014-02-01

In this Letter, we propose an efficient and accurate solution to remove temperature-dependent nonuniformity effects introduced by the imaging optics. This single-image-based approach computes optics-related fixed pattern noise (FPN) by fitting the derivatives of correction model to the gradient components, locally computed on an infrared image. A modified bilateral filtering algorithm is applied to local pixel output variations, so that the refined gradients are most likely caused by the nonuniformity associated with optics. The estimated bias field is subtracted from the raw infrared imagery to compensate the intensity variations caused by optics. The proposed method is fundamentally different from the existing nonuniformity correction (NUC) techniques developed for focal plane arrays (FPAs) and provides an essential image processing functionality to achieve completely shutterless NUC for uncooled long-wave infrared (LWIR) imaging systems.

Modular uncooled video engines based on a DSP processor

NASA Astrophysics Data System (ADS)

Schapiro, F.; Milstain, Y.; Aharon, A.; Neboshchik, A.; Ben-Simon, Y.; Kogan, I.; Lerman, I.; Mizrahi, U.; Maayani, S.; Amsterdam, A.; Vaserman, I.; Duman, O.; Gazit, R.

2011-06-01

The market demand for low SWaP (Size, Weight and Power) uncooled engines keeps growing. Low SWaP is especially critical in battery-operated applications such as goggles and Thermal Weapon Sights. A new approach for the design of the engines was implemented by SCD to optimize size and power consumption at system level. The new approach described in the paper, consists of: 1. A modular hardware design that allows the user to define the exact level of integration needed for his system 2. An "open architecture" based on the OMAPTM530 DSP that allows the integrator to take advantage of unused hardware (FPGA) and software (DSP) resources, for implementation of additional algorithms or functionality. The approach was successfully implemented on the first generation of 25μm pitch BIRD detectors, and more recently on the new, 640 x480, 17 μm pitch detector.

Circuit models applied to the design of a novel uncooled infrared focal plane array structure

NASA Astrophysics Data System (ADS)

Shi, Shali; Chen, Dapeng; Li, Chaobo; Jiao, Binbin; Ou, Yi; Jing, Yupeng; Ye, Tianchun; Guo, Zheying; Zhang, Qingchuan; Wu, Xiaoping

2007-05-01

This paper describes a circuit model applied to the simulation of the thermal response frequency of a novel substrate-free single-layer bi-material cantilever microstructure used as the focal plane array (FPA) in an uncooled opto-mechanical infrared imaging system. In order to obtain a high detection of the IR object, gold (Au) is coated alternately on the silicon nitride (SiNx) cantilevers of the pixels (Shi S et al Sensors and Actuators A at press), whereas the thermal response frequency decreases (Zhao Y 2002 Dissertation University of California, Berkeley). A circuit model for such a cantilever microstructure is proposed to be applied to evaluate the thermal response performance. The pixel's thermal frequency (1/τth) is calculated to be 10 Hz under the optimized design parameters, which is compatible with the response of optical readout systems and human eyes.

Low-Cost WDM-PON With Colorless Bidirectional Transceivers

NASA Astrophysics Data System (ADS)

Shin, Dong Jae; Keh, Y. C.; Kwon, J. W.; Lee, E. H.; Lee, J. K.; Park, M. K.; Park, J. W.; Oh, Y. K.; Kim, S. W.; Yun, I. K.; Shin, H. C.; Heo, D.; Lee, J. S.; Shin, H. S.; Kim, H. S.; Park, S. B.; Jung, D. K.; Hwang, Seongtaek; Oh, Y. J.; Jang, D. H.; Shim, C. S.

2006-01-01

This paper presents a low-cost bidirectional (BiDi) wavelength-division-multiplexed passive optical network (WDM-PON) employing colorless uncooled BiDi transceivers (TRxs) and superluminescent diode (SLD)-based broadband light sources (BLSs). The C band is allocated for upstream and the E+ band for downstream in consideration of BiDi packaging, SLD development, and wavelength alignment of dual-window arrayed waveguide gratings (AWGs). The BiDi TRx integrates an uncooled Fabry-Pérot laser diode (FP-LD), a p-i-n photodiode (PD), and a 45°-angled thin-film filter in a small-form-factor (SFF) package. The SLD-based BLSs provide 13-dBm amplified spontaneous emissions (ASEs) with spectral ripples of < 3 dB and polarization dependencies of < 1 dB. Colorless operations over 32 100-GHz-spaced channels are demonstrated from -20 to 80°C in 155-Mb/s BiDi transmissions over 25 km.

Cooled variable nozzle radial turbine for rotor craft applications

NASA Technical Reports Server (NTRS)

Rogo, C.

1981-01-01

An advanced, small 2.27 kb/sec (5 lbs/sec), high temperature, variable area radial turbine was studied for a rotor craft application. Variable capacity cycles including single-shaft and free-turbine engine configurations were analyzed to define an optimum engine design configuration. Parametric optimizations were made on cooled and uncooled rotor configurations. A detailed structural and heat transfer analysis was conducted to provide a 4000-hour life HP turbine with material properties of the 1988 time frame. A pivoted vane and a moveable sidewall geometry were analyzed. Cooling and variable geometry penalties were included in the cycle analysis. A variable geometry free-turbine engine configuration with a design 1477K (2200 F) inlet temperature and a compressor pressure ratio of 16:1 was selected. An uncooled HP radial turbine rotor with a moveable sidewall nozzle showed the highest performance potential for a time weighted duty cycle.

Uncooled tunneling infrared sensor

NASA Technical Reports Server (NTRS)

Kenny, Thomas W. (Inventor); Kaiser, William J. (Inventor); Podosek, Judith A. (Inventor); Vote, Erika C. (Inventor); Muller, Richard E. (Inventor); Maker, Paul D. (Inventor)

1995-01-01

An uncooled infrared tunneling sensor in which the only moving part is a diaphragm which is deflected into contact with a micromachined silicon tip electrode prepared by a novel lithographic process. Similarly prepared deflection electrodes employ electrostatic force to control the deflection of a silicon nitride, flat diaphragm membrane. The diaphragm exhibits a high resonant frequency which reduces the sensor's sensitivity to vibration. A high bandwidth feedback circuit controls the tunneling current by adjusting the deflection voltage to maintain a constant deflection of the membrane. The resulting infrared sensor can be miniaturized to pixel dimensions smaller than 100 .mu.m. An alternative embodiment is implemented using a corrugated membrane to permit large deflection without complicated clamping and high deflection voltages. The alternative embodiment also employs a pinhole aperture in a membrane to accommodate environmental temperature variation and a sealed chamber to eliminate environmental contamination of the tunneling electrodes and undesireable accoustic coupling to the sensor.

Thermal Damage Done to Bone by Burring and Sawing With and Without Irrigation in Knee Arthroplasty.

PubMed

Tawy, Gwenllian F; Rowe, Philip J; Riches, Philip E

2016-05-01

Heat from bone resecting tools used in knee surgery can induce thermal osteonecrosis, potentially causing aseptic implant loosening. This study compared oscillating saws to burrs in terms of temperature generation and histologic damage. Use of irrigation to reduce bone temperature was also investigated. Temperatures were recorded during sawing and burring with or without irrigation (uncooled or cooled). Histologic analyses were then carried out. Differences between groups were tested statistically (α = 0.05). On average, burring produced higher temperatures than sawing (P < .001). When uncooled irrigation was used, bone temperatures were significantly lower in sawed bone than in burred bone (P < .001). Irrigation lowered temperatures and thermal damage depths and increased osteocyte viability (P < .001). These results suggest that irrigating bone during resection could prevent osteonecrosis onset. Copyright © 2016 Elsevier Inc. All rights reserved.

Assessment of the effect of gaseous fuel delivery mode on thermal efficiency and fuel losses during the valve overlap period in a dual-fuel compression ignition engine

NASA Astrophysics Data System (ADS)

Skrzek, T.

2016-09-01

The paper describes the effect of dual fuelling of single cylinder AVL test CI engine with the use of two ways of gas delivery to the engine manifold. The engine was fuelled diesel oil and propane. For all the tests, gas consumption was maintained at the same level. In the first mode the gas was delivered by injector located under inlet valve. In the second method, there was used a mixer fitted to the intake manifold. The paper compares the results of thermal efficiency and emissions of propane in the exhaust for both fuelling modes. Research clearly show how important it is to synchronize the injector opening time of the intake stroke. This is especially important for supercharged engines in which there is a valve overlap.

Methane Emissions from Leak and Loss Audits of Natural Gas Compressor Stations and Storage Facilities.

PubMed

Johnson, Derek R; Covington, April N; Clark, Nigel N

2015-07-07

As part of the Environmental Defense Fund's Barnett Coordinated Campaign, researchers completed leak and loss audits for methane emissions at three natural gas compressor stations and two natural gas storage facilities. Researchers employed microdilution high-volume sampling systems in conjunction with in situ methane analyzers, bag samples, and Fourier transform infrared analyzers for emissions rate quantification. All sites had a combined total methane emissions rate of 94.2 kg/h, yet only 12% of the emissions total resulted from leaks. Methane slip from exhausts represented 44% of the total emissions. Remaining methane emissions were attributed to losses from pneumatic actuators and controls, engine crankcases, compressor packing vents, wet seal vents, and slop tanks. Measured values were compared with those reported in literature. Exhaust methane emissions were lower than emissions factor estimates for engine exhausts, but when combined with crankcase emissions, measured values were 11.4% lower than predicted by AP-42 as applicable to emissions factors for four-stroke, lean-burn engines. Average measured wet seal emissions were 3.5 times higher than GRI values but 14 times lower than those reported by Allen et al. Reciprocating compressor packing vent emissions were 39 times higher than values reported by GRI, but about half of values reported by Allen et al. Though the data set was small, researchers have suggested a method to estimate site-wide emissions factors for those powered by four-stroke, lean-burn engines based on fuel consumption and site throughput.

Hot ion plasma production in HIP-1 using water-cooled hollow cathodes

NASA Technical Reports Server (NTRS)

Reinmann, J. J.; Lauver, M. R.; Patch, R. W.; Layman, R. W.; Snyder, A.

1975-01-01

The paper reports on hot-ion plasma experiments conducted in a magnetic mirror facility. A steady-state E x B plasma was formed by applying a strong radially inward dc electric field near the mirror throats. Most of the results were for hydrogen, but deuterium and helium plasmas were also studied. Three water-cooled hollow cathodes were operated in the hot-ion plasma mode with the following results: (1) thermally emitting cathodes were not required to achieve the hot-ion mode; (2) steady-state operation (several minutes) was attained; (3) input powers greater than 40 kW were achieved; (4) cathode outside diameters were increased from 1.2 cm (uncooled) to 4.4 cm (water-cooled); (5) steady-state hydrogen plasmas with ion temperatures from 185 to 770 eV and electron temperatures from 5 to 21 eV were produced. Scaling relations were empirically obtained for discharge current, ion temperature, electron temperature, and relative ion density as a function of hydrogen gas feed rate, magnetic field, and cathode voltage.

Micromachined electron tunneling infrared sensors

NASA Technical Reports Server (NTRS)

Kenny, T. W.; Kaiser, W. J.; Podosek, J. A.; Rockstad, H. K.; Reynolds, J. K.

1993-01-01

The development of an improved Golay cell is reported. This new sensor is constructed entirely from micromachined silicon components. A silicon oxynitride (SiO(x)N(y)) membrane is deflected by the thermal expansion of a small volume of trapped gas. To detect the motion of the membrane, an electron tunneling transducer is used. This sensor detects electrons which tunnel through the classically forbidden barrier between a tip and a surface; the electron current is exponentially dependent on the separation between the tip and the surface. The sensitivity of tunneling transducers constructed was typically better than 10(exp -3) A/square root of Hz. Through use of the electron tunneling transducer, the scaling laws which have prevented the miniaturization of the Golay cell are avoided. This detector potentially offers low cost fabrication, compatibility with silicon readout electronics, and operation without cooling. Most importantly, this detector may offer better sensitivity than any other uncooled infrared sensor, with the exception of the original Golay cell.

Gasdynamic modeling and parametric study of mesoscale internal combustion swing engine/generator systems

NASA Astrophysics Data System (ADS)

Gu, Yongxian

The demand of portable power generation systems for both domestic and military applications has driven the advances of mesoscale internal combustion engine systems. This dissertation was devoted to the gasdynamic modeling and parametric study of the mesoscale internal combustion swing engine/generator systems. First, the system-level thermodynamic modeling for the swing engine/generator systems has been developed. The system performance as well as the potentials of both two- and four-stroke swing engine systems has been investigated based on this model. Then through parameterc studies, the parameters that have significant impacts on the system performance have been identified, among which, the burn time and spark advance time are the critical factors related to combustion process. It is found that the shorter burn time leads to higher system efficiency and power output and the optimal spark advance time is about half of the burn time. Secondly, the turbulent combustion modeling based on levelset method (G-equation) has been implemented into the commercial software FLUENT. Thereafter, the turbulent flame propagation in a generic mesoscale combustion chamber and realistic swing engine chambers has been studied. It is found that, in mesoscale combustion engines, the burn time is dominated by the mean turbulent kinetic energy in the chamber. It is also shown that in a generic mesoscale combustion chamber, the burn time depends on the longest distance between the initial ignition kernel to its walls and by changing the ignition and injection locations, the burn time can be reduced by a factor of two. Furthermore, the studies of turbulent flame propagation in real swing engine chambers show that the combustion can be enhanced through in-chamber turbulence augmentation and with higher engine frequency, the burn time is shorter, which indicates that the in-chamber turbulence can be induced by the motion of moving components as well as the intake gas jet flow. The burn time for current two-stroke swing engine is estimated as about 2.5 ms, which can be used in the prescribed burned mass fraction profile that follows the Wiebe's function. Finally, a 2D CFD code for compressible flow has been developed to study wave interactions in the engine and header system. It is found that with realistic working conditions, for a two-stroke swing engine, certain expansion waves can be created by the exhaust gas flows and the chamber pressure can reach as low as 5 psi below one atmosphere, which helps fill fresh reactant charge. The results also show that to obtain appropriate header tuning for the current two-stroke swing engine, the length of the header neck is about 40 cm.

Application of infrared uncooled cameras in surveillance systems

NASA Astrophysics Data System (ADS)

Dulski, R.; Bareła, J.; Trzaskawka, P.; PiÄ tkowski, T.

2013-10-01

The recent necessity to protect military bases, convoys and patrols gave serious impact to the development of multisensor security systems for perimeter protection. One of the most important devices used in such systems are IR cameras. The paper discusses technical possibilities and limitations to use uncooled IR camera in a multi-sensor surveillance system for perimeter protection. Effective ranges of detection depend on the class of the sensor used and the observed scene itself. Application of IR camera increases the probability of intruder detection regardless of the time of day or weather conditions. It also simultaneously decreased the false alarm rate produced by the surveillance system. The role of IR cameras in the system was discussed as well as technical possibilities to detect human being. Comparison of commercially available IR cameras, capable to achieve desired ranges was done. The required spatial resolution for detection, recognition and identification was calculated. The simulation of detection ranges was done using a new model for predicting target acquisition performance which uses the Targeting Task Performance (TTP) metric. Like its predecessor, the Johnson criteria, the new model bounds the range performance with image quality. The scope of presented analysis is limited to the estimation of detection, recognition and identification ranges for typical thermal cameras with uncooled microbolometer focal plane arrays. This type of cameras is most widely used in security systems because of competitive price to performance ratio. Detection, recognition and identification range calculations were made, and the appropriate results for the devices with selected technical specifications were compared and discussed.

A novel readout integrated circuit for ferroelectric FPA detector

NASA Astrophysics Data System (ADS)

Bai, Piji; Li, Lihua; Ji, Yulong; Zhang, Jia; Li, Min; Liang, Yan; Hu, Yanbo; Li, Songying

2017-11-01

Uncooled infrared detectors haves some advantages such as low cost light weight low power consumption, and superior reliability, compared with cryogenically cooled ones Ferroelectric uncooled focal plane array(FPA) are being developed for its AC response and its high reliability As a key part of the ferroelectric assembly the ROIC determines the performance of the assembly. A top-down design model for uncooled ferroelectric readout integrated circuit(ROIC) has been developed. Based on the optical thermal and electrical properties of the ferroelectric detector the RTIA readout integrated circuit is designed. The noise bandwidth of RTIA readout circuit has been developed and analyzed. A novel high gain amplifier, a high pass filter and a low pass filter circuits are designed on the ROIC. In order to improve the ferroelectric FPA package performance and decrease of package cost a temperature sensor is designed on the ROIC chip At last the novel RTIA ROIC is implemented on 0.6μm 2P3M CMOS silicon techniques. According to the experimental chip test results the temporal root mean square(RMS)noise voltage is about 1.4mV the sensitivity of the on chip temperature sensor is 0.6 mV/K from -40°C to 60°C the linearity performance of the ROIC chip is better than 99% Based on the 320×240 RTIA ROIC, a 320×240 infrared ferroelectric FPA is fabricated and tested. Test results shows that the 320×240 RTIA ROIC meets the demand of infrared ferroelectric FPA.

Wide-band gas leak imaging detection system using UFPA

NASA Astrophysics Data System (ADS)

Jin, Wei-qi; Li, Jia-kun; Dun, Xiong; Jin, Minglei; Wang, Xia

2014-11-01

The leakage of toxic or hazardous gases not only pollutes the environment, but also threatens people's lives and property safety. Many countries attach great importance to the rapid and effective gas leak detection technology and instrument development. However, the gas leak imaging detection systems currently existing are generally limited to a narrow-band in Medium Wavelength Infrared (MWIR) or Long Wavelength Infrared (LWIR) cooled focal plane imaging, which is difficult to detect the common kinds of the leaking gases. Besides the costly cooled focal plane array is utilized, the application promotion is severely limited. To address this issue, a wide-band gas leak IR imaging detection system using Uncooled Focal Plane Array (UFPA) detector is proposed, which is composed of wide-band IR optical lens, sub-band filters and switching device, wide-band UFPA detector, video processing and system control circuit. A wide-band (3µm~12µm) UFPA detector is obtained by replacing the protection window and optimizing the structural parameters of the detector. A large relative aperture (F#=0.75) wide-band (3μm~12μm) multispectral IR lens is developed by using the focus compensation method, which combining the thickness of the narrow-band filters. The gas leak IR image quality and the detection sensitivity are improved by using the IR image Non-Uniformity Correction (NUC) technology and Digital Detail Enhancement (DDE) technology. The wide-band gas leak IR imaging detection system using UFPA detector takes full advantage of the wide-band (MWIR&LWIR) response characteristic of the UFPA detector and the digital image processing technology to provide the resulting gas leak video easy to be observed for the human eyes. Many kinds of gases, which are not visible to the naked eyes, can be sensitively detected and visualized. The designed system has many commendable advantages, such as scanning a wide range simultaneously, locating the leaking source quickly, visualizing the gas plume intuitively and so on. The simulation experiment shows that the gas IR imaging detection has great advantages and widely promotion space compared with the traditional techniques, such as point-contact or line-contactless detection.

Two Kinds of Stroke

MedlinePlus

... Issue Past Issues Special Section Two Kinds of Stroke Past Issues / Summer 2007 Table of Contents For ... are often a warning sign for future strokes. Stroke Can Affect Anyone Award-winning actress Julie Harris ...

Estimating gas kick arrival to better manage surface flow

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

Merryman, J.

1997-06-01

There are many quality, expertly designed programs for teaching rig crews prevention and control of well kicks. Much time and money has been spent training rig crews for procedures and methods to avoid kicks, and what to do if you have one, even though all accepted practices were followed. One false/bad result from this training is that individuals have come away from this training believing that once a gas kick is circulated through the choke, all problems are simple and manageable, i.e., the danger has passed. What you do with gas once it is downstream of the choke has notmore » been given enough emphasis in some training programs, including the one the author is involved in. This article, prepared from experiences on actual rig locations in Wyoming and Argentina, and developed for well control training in Parker Drilling Co.`s Training Center, Odessa, Texas, describes a method for estimating the time, in pump strokes and/or minutes, for a gas kick to reach surface. Reducing pump strokes (circulating flowrate) and knowing available time to gas kick arrival allows the crew to prepare surface handling equipment. Common misconceptions about gas handling and potential resulting problems are noted. An example calculation describes the calculation procedure.« less

PIGC™ - A low cost fugitive emissions and methane detection system using advanced gas filter correlation techniques for local and wide area monitoring

NASA Astrophysics Data System (ADS)

Lachance, R. L.; Gordley, L. L.; Marshall, B. T.; Fisher, J.; Paxton, G.; Gubeli, J. F.

2015-12-01

Currently there is no efficient and affordable way to monitor gas releases over small to large areas. We have demonstrated the ability to accurately measure key greenhouse and pollutant gasses with low cost solar observations using the breakthrough sensor technology called the "Pupil Imaging Gas Correlation", PIGC™, which provides size and complexity reduction while providing exceptional resolution and coverage for various gas sensing applications. It is a practical implementation of the well-known Gas Filter Correlation Radiometry (GFCR) technique used for the HALOE and MOPITT satellite instruments that were flown on successful NASA missions in the early 2000s. This strong space heritage brings performance and reliability to the ground instrument design. A methane (CH4) abundance sensitivity of 0.5% or better of ambient column with uncooled microbolometers has been demonstrated with 1 second direct solar observations. These under $10 k sensors can be deployed in precisely balanced autonomous grids to monitor the flow of chosen gasses, and infer their source locations. Measureable gases include CH4, 13CO2, N2O, NO, NH3, CO, H2S, HCN, HCl, HF, HDO and others. A single instrument operates in a dual operation mode, at no additional cost, for continuous (real-time 24/7) local area perimeter monitoring for the detection of leaks for safety & security needs, looking at an artificial light source (for example a simple 60 W light bulb placed 100 m away), while simultaneously allowing solar observation for quasi-continuous wide area total atmospheric column scanning (3-D) for environmental monitoring (fixed and mobile configurations). The second mode of operation continuously quantifies the concentration and flux of specific gases over different ground locations, determined the amount of targeted gas being released from the area or getting into the area from outside locations, allowing better tracking of plumes and identification of sources. This paper reviews the measurement technique, performance demonstration and grid deployment strategy.

Incidence loss for a core turbine rotor blade in a two-dimensional cascade

NASA Technical Reports Server (NTRS)

Stabe, R. G.; Kline, J. F.

1974-01-01

The effect of incidence angle on the aerodynamic performance of an uncooled core turbine rotor blade was investigated experimentally in a two-dimensional cascade. The cascade test covered a range of incidence angles from minus 15 deg to 15 deg in 5-degree increments and a range of pressure ratios corresponding to ideal exit critical velocity ratios of 0.6 to 0.95. The principal measurements were blade-surface static pressures and cross-channel surveys of exit total pressure, static pressure, and flow angle. The results of the investigation include blade-surface velocity distribution and overall performance in terms of weight flow and loss for the range of incidence angles and exit velocity ratios investigated. The measured losses are also compared with two common methods of predicting incidence loss.

40 CFR 205.55-2 - Compliance with standards.

Code of Federal Regulations, 2012 CFR

2012-07-01

... following parameters (a manufacturer may use more parameters): (a) Engine type. (1) Gasoline—two stroke cycle. (2) Gasoline—four stroke cycle. (3) Diesel—two stroke cycle. (4) Diesel—four stroke cycle. (5...

40 CFR 205.55-2 - Compliance with standards.

Code of Federal Regulations, 2014 CFR

2014-07-01

... following parameters (a manufacturer may use more parameters): (a) Engine type. (1) Gasoline—two stroke cycle. (2) Gasoline—four stroke cycle. (3) Diesel—two stroke cycle. (4) Diesel—four stroke cycle. (5...

40 CFR 204.55-2 - Requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... parameters): (A) Engine type. (1) Gasoline—two stroke cycle (2) Gasoline—four stroke cycle (3) Diesel—two stroke cycle (4) Diesel—four stroke cycle (5) Rotary—Wankel (6) Turbine (7) Other (B) Engine manufacturer...

40 CFR 204.55-2 - Requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... use more parameters): (A) Engine type. (1) Gasoline—two stroke cycle (2) Gasoline—four stroke cycle (3) Diesel—two stroke cycle (4) Diesel—four stroke cycle (5) Rotary—Wankel (6) Turbine (7) Other (B) Engine...

40 CFR 204.55-2 - Requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... use more parameters): (A) Engine type. (1) Gasoline—two stroke cycle (2) Gasoline—four stroke cycle (3) Diesel—two stroke cycle (4) Diesel—four stroke cycle (5) Rotary—Wankel (6) Turbine (7) Other (B) Engine...

Analysis of chain saw lubricating oils commonly used in Thailand's southern border provinces for forensic science purpose.

PubMed

Choodum, Aree; Tripuwanard, Kijja; Daeid, Niamh Nic

2014-08-01

In recent years, Thailand's southern border provinces (Malay-Muslim-majority border provinces) have become the scene of violence and insurgency. One of the attack patterns is the blocking of roads with perennial plants followed by planned attacks using improvised explosive devices (IEDs) or weapons on first responders. Containers of viscous dark lubricating oil and traces of lubricants on the felled trees were usually found at the scene. These were suspected to be chain oil lubricant from the chainsaws used to cut down the trees used for the roadblock. This work aimed to differentiate the chromatographic patterns of used lubricating oils available in automobile repair shops from various locations across Thailand's southern border provinces. Lubricating oils were analyzed using gas chromatography/flame ionization detector (GC/FID) every two weeks to study their variation in chemical compositions over time. The results obtained from GC/FID were normalized for differentiation. This included four two-stroke, six four-stroke, and three recycled oils. Two lubricating oils found at an incident scene were also analyzed and the results compared with the chain oil from five seized chainsaws. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Electron microscopic evidence for the myosin head lever arm mechanism in hydrated myosin filaments using the gas environmental chamber

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

Minoda, Hiroki; CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012; Okabe, Tatsuhiro

2011-02-25

Research highlights: {yields} We succeeded in recording structural changes of hydrated myosin cross-bridges. {yields} We succeeded in position-marking the cross-bridges with site-directed antibodies. {yields} We recorded cross-bridge movement at different regions in individual cross-bridge. {yields} The movement was smallest at the cross-bridge-subfragment two boundary. {yields} The results provide evidence for the cross-bridge lever arm mechanism. -- Abstract: Muscle contraction results from an attachment-detachment cycle between the myosin heads extending from myosin filaments and the sites on actin filaments. The myosin head first attaches to actin together with the products of ATP hydrolysis, performs a power stroke associated with release ofmore » hydrolysis products, and detaches from actin upon binding with new ATP. The detached myosin head then hydrolyses ATP, and performs a recovery stroke to restore its initial position. The strokes have been suggested to result from rotation of the lever arm domain around the converter domain, while the catalytic domain remains rigid. To ascertain the validity of the lever arm hypothesis in muscle, we recorded ATP-induced movement at different regions within individual myosin heads in hydrated myosin filaments, using the gas environmental chamber attached to the electron microscope. The myosin head were position-marked with gold particles using three different site-directed antibodies. The amplitude of ATP-induced movement at the actin binding site in the catalytic domain was similar to that at the boundary between the catalytic and converter domains, but was definitely larger than that at the regulatory light chain in the lever arm domain. These results are consistent with the myosin head lever arm mechanism in muscle contraction if some assumptions are made.« less

New solutions and technologies for uncooled infrared imaging

NASA Astrophysics Data System (ADS)

Rollin, Joël.; Diaz, Frédéric; Fontaine, Christophe; Loiseaux, Brigitte; Lee, Mane-Si Laure; Clienti, Christophe; Lemonnier, Fabrice; Zhang, Xianghua; Calvez, Laurent

2013-06-01

The military uncooled infrared market is driven by the continued cost reduction of the focal plane arrays whilst maintaining high standards of sensitivity and steering towards smaller pixel sizes. As a consequence, new optical solutions are called for. Two approaches can come into play: the bottom up option consists in allocating improvements to each contributor and the top down process rather relies on an overall optimization of the complete image channel. The University of Rennes I with Thales Angénieux alongside has been working over the past decade through French MOD funding's, on low cost alternatives of infrared materials based upon chalcogenide glasses. A special care has been laid on the enhancement of their mechanical properties and their ability to be moulded according to complex shapes. New manufacturing means developments capable of better yields for the raw materials will be addressed, too. Beyond the mere lenses budget cuts, a wave front coding process can ease a global optimization. This technic gives a way of relaxing optical constraints or upgrading thermal device performances through an increase of the focus depths and desensitization against temperature drifts: it combines image processing and the use of smart optical components. Thales achievements in such topics will be enlightened and the trade-off between image quality correction levels and low consumption/ real time processing, as might be required in hand-free night vision devices, will be emphasized. It is worth mentioning that both approaches are deeply leaning on each other.

Energy expenditure in chronic stroke patients playing Wii Sports: a pilot study

PubMed Central

2011-01-01

Background Stroke is one of the leading causes of long-term disability in modern western countries. Stroke survivors often have functional limitations which might lead to a vicious circle of reduced physical activity, deconditioning and further physical deterioration. Current evidence suggests that routine moderate- or vigorous-intensity physical activity is essential for maintenance and improvement of health among stroke survivors. Nevertheless, long-term participation in physical activities is low among people with disabilities. Active video games, such as Nintendo Wii Sports, might maintain interest and improve long-term participation in physical activities; however, the intensity of physical activity among chronic stroke patients while playing Wii Sports is unknown. We investigated the energy expenditure of chronic stroke patients while playing Wii Sports tennis and boxing. Methods Ten chronic (≥ 6 months) stroke patients comprising a convenience sample, who were able to walk independently on level ground, were recruited from a rehabilitation centre. They were instructed to play Wii Sports tennis and boxing in random order for 15 minutes each, with a 10-minute break between games. A portable gas analyzer was used to measure oxygen uptake (VO2) during sitting and during Wii Sports game play. Energy expenditure was expressed in metabolic equivalents (METs), calculated as VO2 during Wii Sports divided by VO2 during sitting. We classified physical activity as moderate (3-6 METs) or vigorous (> 6 METs) according to the American College of Sports Medicine and the American Heart Association Guidelines. Results Among the 10 chronic stroke patients, 3 were unable to play tennis because they had problems with timing of hitting the ball, and 2 were excluded from the boxing group because of a technical problem with the portable gas analyzer. The mean (± SD) energy expenditure during Wii Sports game play was 3.7 (± 0.6) METs for tennis and 4.1 (± 0.7) METs for boxing. All 8 participants who played boxing and 6 of the 7 who played tennis attained energy expenditures > 3 METs. Conclusions With the exception of one patient in the tennis group, chronic stroke patients played Wii Sports tennis and boxing at moderate-intensity, sufficient for maintaining and improving health in this population. PMID:21756315

Uncooled Tunable LWIR Microbolometer

DTIC Science & Technology

2010-05-05

switches [19], micromirrors in projection displays [20], and tunable thermal detectors [21, 22], etc. In all these devices, contact must be achieved...Failure Mechanisms of the Digital Micromirror Device (DMD)”, Proc. 36th Annual Intl. Reliability Physics Symposium, Reno, NV, pp. 9-16, 1998. [33

40 CFR 90.104 - Compliance with emission standards.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Volume Engine Families Engine class Two-stroke engines 1 HC+NOX CO Four-stroke engines HC+NOX CO Engines...). Class IV 1.1 1.1 1.5 1.1 Class V 1.1 1.1 1.5 1.1 1 Two-stroke technologies to which these assigned deterioration factors apply include conventional two-strokes, compression wave designs, and stratified...

40 CFR 90.104 - Compliance with emission standards.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Volume Engine Families Engine class Two-stroke engines 1 HC+NOX CO Four-stroke engines HC+NOX CO Engines...). Class IV 1.1 1.1 1.5 1.1 Class V 1.1 1.1 1.5 1.1 1 Two-stroke technologies to which these assigned deterioration factors apply include conventional two-strokes, compression wave designs, and stratified...

40 CFR 90.104 - Compliance with emission standards.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Volume Engine Families Engine class Two-stroke engines 1 HC+NOX CO Four-stroke engines HC+NOX CO Engines...). Class IV 1.1 1.1 1.5 1.1 Class V 1.1 1.1 1.5 1.1 1 Two-stroke technologies to which these assigned deterioration factors apply include conventional two-strokes, compression wave designs, and stratified...

40 CFR 90.104 - Compliance with emission standards.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Volume Engine Families Engine class Two-stroke engines 1 HC+NOX CO Four-stroke engines HC+NOX CO Engines...). Class IV 1.1 1.1 1.5 1.1 Class V 1.1 1.1 1.5 1.1 1 Two-stroke technologies to which these assigned deterioration factors apply include conventional two-strokes, compression wave designs, and stratified...

40 CFR 90.104 - Compliance with emission standards.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Volume Engine Families Engine class Two-stroke engines 1 HC+NOX CO Four-stroke engines HC+NOX CO Engines...). Class IV 1.1 1.1 1.5 1.1 Class V 1.1 1.1 1.5 1.1 1 Two-stroke technologies to which these assigned deterioration factors apply include conventional two-strokes, compression wave designs, and stratified...

Next generation cooled long range thermal sights with minimum size, weight, and power

NASA Astrophysics Data System (ADS)

Breiter, R.; Ihle, T.; Wendler, J.; Rühlich, I.; Ziegler, J.

2013-06-01

Situational awareness and precise targeting at day, night and severe weather conditions are key elements for mission success in asymmetric warfare. To support these capabilities for the dismounted soldier, AIM has developed a family of stand-alone thermal weapon sights based on high performance cooled IR-modules which are used e.g. in the infantryman of the future program of the German army (IdZ). The design driver for these sights is a long ID range <1500m for the NATO standard target to cover the operational range of a platoon with the engagement range of .50 cal rifles, 40mm AGLs or for reconnaissance tasks. The most recent sight WBZG has just entered into serial production for the IdZ enhanced system of the German army with additional capabilities like a wireless data link to the soldier backbone computer. Minimum size, weight and power (SWaP) are most critical requirements for the dismounted soldiers' equipment and sometimes push a decision towards uncooled equipment with marginal performance referring to the outstanding challenges in current asymmetric warfare, e.g. the capability to distinguish between combatants and non-combatants in adequate ranges. To provide the uncompromised e/o performance with SWaP parameters close to uncooled, AIM has developed a new thermal weapon sight based on high operating temperature (HOT) MCT MWIR FPAs together with a new low power single piston stirling cooler. In basic operation the sight is used as a clip-on in front of the rifle scope. An additional eyepiece for stand-alone targeting with e.g. AGLs or a biocular version for relaxed surveillance will be available. The paper will present details of the technologies applied for such long range cooled sights with size, weight and power close to uncooled.

Uncooled spectrometer for x-ray astrophysics

NASA Astrophysics Data System (ADS)

Urban, Martin; Nentvich, Ondrej; Stehlikova, Veronika; Sieger, Ladislav

2017-05-01

In the field of X-ray detection for Astrophysics there are mainly two objectives; first is to create 2D images as a result of sensing radiation by detectors consisting of a pixels matrix and the second is a spectral analysis of the incident radiation. For spectral analysis, the basis is usually the principle of diffraction. This paper describes the new design of X-ray spectrometer based on Timepix detector with optics positioned in front of it. The advantage of this setup is the ability to get the image and spectrum from the same devices. With other modifications is possible to shift detection threshold into areas of soft X-ray radiation.

The two-stroke poppet valve engine. Part 1: Intake and exhaust ports flow experimental assessments

NASA Astrophysics Data System (ADS)

Kamili Zahidi, M.; Razali Hanipah, M.; Ramasamy, D.; Noor, M. M.; Kadirgama, K.; Rahman, M. M.

2017-10-01

A two-stroke poppet valve engine is developed to overcome the common problems in conventional two-stroke engine designs. However, replacing piston control port with poppet valve will resulted different flow behaviour. This paper is looking at experimental assessment on a two-stroke poppet valve engine configuration to investigate the port flow performance. The aims are to evaluate the intake and exhaust coefficient of discharge and assess the twostroke capability of the cylinder head. The results has shown comparable coefficient of discharge values as production engine for the intake while the exhaust has higher values which is favourable for the two-stroke cycle operation.

Community Based Participatory Research: A New approach to engaging community members to rapidly call 911 for Stroke

PubMed Central

Skolarus, Lesli E.; Zimmerman, Marc A.; Murphy, Jillian; Brown, Devin L.; Kerber, Kevin A.; Bailey, Sarah; Fowlkes, Sophronia; Morgenstern, Lewis B.

2014-01-01

Background and Purpose Acute stroke treatments are underutilized primarily due to delayed hospital arrival. Using a community based participatory research approach, we explored stroke self-efficacy, knowledge and perceptions of stroke among a predominately African American population in Flint, Michigan. Methods In March 2010, a survey was administered to youth and adults after religious services at three churches and one church health day. The survey consisted of vignettes (12 stroke, 4 non-stroke) to assess knowledge of stroke warning signs and behavioral intent to call 911. The survey also assessed stroke self-efficacy, personal knowledge of someone who had had a stroke, personal history of stroke and barriers to calling 911. Linear regression models explored the association of stroke self-efficacy with behavioral intent to call 911 among adults. Results Two hundred forty two adults and 90 youth completed the survey. Ninety two percent of adults and 90% of youth respondents were African American. Responding to 12 stroke vignettes, adults would call 911 in 72% (sd=0.26) of the vignettes while youth would call 911 in 54% (sd=0.29) (p<0.001). Adults correctly identified stroke in 51% (sd=0.32) of the stroke vignettes and youth in 46% (sd=0.28) of the stroke vignettes (p=0.28). Stroke self-efficacy predicted behavioral intent to call 911 (p=0.046). Conclusion In addition to knowledge of stroke warning signs, behavioral interventions to increase both stroke self-efficacy and behavioral intent may be useful for helping people make appropriate 911 calls for stroke. A community based participatory research approach may be effective in reducing stroke disparities. PMID:21617148

Community-based participatory research: a new approach to engaging community members to rapidly call 911 for stroke.

PubMed

Skolarus, Lesli E; Zimmerman, Marc A; Murphy, Jillian; Brown, Devin L; Kerber, Kevin A; Bailey, Sarah; Fowlkes, Sophronia; Morgenstern, Lewis B

2011-07-01

Acute stroke treatments are underutilized primarily because of delayed hospital arrival. Using a community-based participatory research approach, we explored stroke self-efficacy, knowledge, and perceptions of stroke among a predominately African American population in Flint, Michigan. In March 2010, a survey was administered to youth and adults after religious services at 3 churches and during 1 church health day. The survey consisted of vignettes (12 stroke, 4 nonstroke) to assess knowledge of stroke warning signs and behavioral intent to call 911. The survey also assessed stroke self-efficacy, personal knowledge of someone who had experienced a stroke, personal history of stroke, and barriers to calling 911. Linear regression models explored the association of stroke self-efficacy with behavioral intent to call 911 among adults. Two hundred forty-two adults and 90 youths completed the survey. Ninety-two percent of adults and 90% of youth respondents were African American. Responding to 12 stroke vignettes, adults would call 911 in 72% (SD, 0.26) of the vignettes, whereas youths would call 911 in 54% of vignettes (SD, 0.29; P<0.001). Adults correctly identified stroke in 51% (SD, 0.32) of the stroke vignettes and youth correctly identified stroke in 46% (SD, 0.28) of the stroke vignettes (P=0.28). Stroke self-efficacy predicted behavioral intent to call 911 (P=0.046). In addition to knowledge of stroke warning signs, behavioral interventions to increase both stroke self-efficacy and behavioral intent may be useful for helping people make appropriate 911 calls for stroke. A community-based participatory research approach may be effective in reducing stroke disparities.

The Possible Relationship Between Patent Foramen Ovale and Decompression Sickness:.

DTIC Science & Technology

1999-01-01

a potential conduit for blood clot (resulting in a stroke), or venous gas bubbles during decompression, (resulting in type II neurologic...Despite the high prevalence of PFO in the general population, and the relatively common occurrence of venous gas bubbles in diving and altitude exposures...being present in up to a third of the population. The potential for right- to-left shunting of venous gas emboli (VGE) which are known to occur in even

Test-Retest Reproducibility of Two Short-Form Balance Measures Used in Individuals with Stroke

ERIC Educational Resources Information Center

Liaw, Lih-Jiun; Hsieh, Ching-Lin; Hsu, Miao-Ju; Chen, Hui-Mei; Lin, Jau-Hong; Lo, Sing-Kai

2012-01-01

The aim of this study is to determine the test-retest reproducibility of the seven-item Short-Form Berg Balance Scale (SFBBS) and the five-item Short-Form Postural Assessment Scale for Stroke Patients (SFPASS) in individuals with chronic stroke. Fifty-two chronic stroke patients from two rehabilitation departments were included in the study. Both…

Progress of the Swedish-Australian research collaboration on uncooled smart IR sensors

NASA Astrophysics Data System (ADS)

Liddiard, Kevin C.; Ringh, Ulf; Jansson, Christer; Reinhold, Olaf

1998-10-01

Progress is reported on the development of uncooled microbolometer IR focal plane detector arrays (IRFPDA) under a research collaboration between the Swedish Defence Research Establishment (FOA), and the Defence Science and Technology Organization (DSTO), Australia. The paper describes current focal plane detector arrays designed by Electro-optic Sensor Design (EOSD) for readout circuits developed by FOA. The readouts are fabricated in 0.8 micrometer CMOS, and have a novel signal conditioning and 16 bit parallel ADC design. The arrays are post-processed at DSTO on wafers supplied by FOA. During the past year array processing has been carried out at a new microengineering facility at DSTO, Salisbury, South Australia. A number of small format 16 X 16 arrays have been delivered to FOA for evaluation, and imaging has been demonstrated with these arrays. A 320 X 240 readout with 320 parallel 16 bit ADCs has been developed and IRFPDAs for this readout have been fabricated and are currently being evaluated.

Nonimaging applications for microbolometer arrays

NASA Astrophysics Data System (ADS)

Picard, Francis; Jerominek, Hubert; Pope, Timothy D.; Zhang, Rose; Ngo, Linh P.; Tremblay, Bruno; Tasker, Nick; Grenier, Carol; Bilodeau, Ghislain; Cayer, Felix; Lehoux, Mario; Alain, Christine; Larouche, Carl; Savard, Simon

2001-10-01

In an effort to leverage uncooled microbolometer technology, testing of bolometer performance in various nonimaging applications has been performed. One of these applications makes use of an uncooled microbolometer array as the sensing element for a laser beam analyzer. Results of the characterization of cw CO2 laser beams with this analyzer are given. A comparison with the results obtained with a commercial laser beam analyzer is made. Various advantages specific to microbolometer arrays for this application are identified. A second application makes use of microbolometers for absolute temperature measurements. The experimental method and results are described. The technique's limitations and possible implementations are discussed. Finally, the third application evaluated is related to the rapidly expanding field of biometry. It consists of using a modified microbolometer array for fingerprint sensing. The basic approach allowing the use of microbolometers for such an application is discussed. The results of a proof-of-principle experiment are described. Globally, the described work illustrates the fact that microbolometer array fabrication technology can be exploited for many important applications other than IR imaging.

Performance and Results from a Space Borne, Uncooled Microbolometer Array Spectral Radiometric Imager

NASA Technical Reports Server (NTRS)

Spinhirne, James M; Scott, V. Stan; Lancaster, Redgie S.; Manizade, Kathrine; Palm, Steven P.

2000-01-01

The Infrared Spectral Imaging Radiometer experiment was flown on a space shuttle mission as a shuttle hitchhiker experiment in August of 1997. The goals of the experiment were to test uncooled array detectors for infrared spectral imaging from space and to apply for the first time retrieval from space of brightness temperatures of cloud, land and sea along with direct laser measurements of cloud top height. The instrument operates in 3 narrow and one broad spectral band, all between 7 and 13 microns in either stare or time-delay and integration mode. The nominal spatial resolution was 1/4 kilometer. Using onboard calibrations along with periodic views of deep space, radiometric calibration of imagery was carried out and performance analyzed. The noise equivalent temperature difference and absolute accuracy reported here varied with operating mode, spectral band and scene temperature but were within requirements. This paper provides a description of the instrument, its operating modes, the method of brightness temperature retrieval, the method of spectral registration and results from the flight.

Pyroelectric Materials for Uncooled Infrared Detectors: Processing, Properties, and Applications

NASA Technical Reports Server (NTRS)

Aggarwal, M. D.; Batra, A. K.; Guggilla, P.; Edwards, M. E.; Penn, B. G.; Currie, J. R., Jr.

2010-01-01

Uncooled pyroelectric detectors find applications in diverse and wide areas such as industrial production; automotive; aerospace applications for satellite-borne ozone sensors assembled with an infrared spectrometer; health care; space exploration; imaging systems for ships, cars, and aircraft; and military and security surveillance systems. These detectors are the prime candidates for NASA s thermal infrared detector requirements. In this Technical Memorandum, the physical phenomena underlying the operation and advantages of pyroelectric infrared detectors is introduced. A list and applications of important ferroelectrics is given, which is a subclass of pyroelectrics. The basic concepts of processing of important pyroelectrics in various forms are described: single crystal growth, ceramic processing, polymer-composites preparation, and thin- and thick-film fabrications. The present status of materials and their characteristics and detectors figures-of-merit are presented in detail. In the end, the unique techniques demonstrated for improving/enhancing the performance of pyroelectric detectors are illustrated. Emphasis is placed on recent advances and emerging technologies such as thin-film array devices and novel single crystal sensors.

Performance of CO2 enrich CNG in direct injection engine

NASA Astrophysics Data System (ADS)

Firmansyah, W. B.; Ayandotun, E. Z.; Zainal, A.; Aziz, A. R. A.; Heika, M. R.

2015-12-01

This paper investigates the potential of utilizing the undeveloped natural gas fields in Malaysia with high carbon dioxide (CO2) content ranging from 28% to 87%. For this experiment, various CO2 proportions by volume were added to pure natural gas as a way of simulating raw natural gas compositions in these fields. The experimental tests were carried out using a 4-stroke single cylinder spark ignition (SI) direct injection (DI) compressed natural gas (CNG) engine. The tests were carried out at 180° and 300° before top dead centre (BTDC) injection timing at 3000 rpm, to establish the effects on the engine performance. The results show that CO2 is suppressing the combustion of CNG while on the other hand CNG combustion is causing CO2 dissociation shown by decreasing CO2 emission with the increase in CO2 content. Results for 180° BTDC injection timing shows higher performance compared to 300° BTDC because of two possible reasons, higher volumetric efficiency and higher stratification level. The results also showed the possibility of increasing the CO2 content by injection strategy.

Intensive virtual reality-based training for upper limb motor function in chronic stroke: a feasibility study using a single case experimental design and fMRI.

PubMed

Schuster-Amft, Corina; Henneke, Andrea; Hartog-Keisker, Birgit; Holper, Lisa; Siekierka, Ewa; Chevrier, Edith; Pyk, Pawel; Kollias, Spyros; Kiper, Daniel; Eng, Kynan

2015-01-01

To evaluate feasibility and neurophysiological changes after virtual reality (VR)-based training of upper limb (UL) movements. Single-case A-B-A-design with two male stroke patients (P1:67 y and 50 y, 3.5 and 3 y after onset) with UL motor impairments, 45-min therapy sessions 5×/week over 4 weeks. Patients facing screen, used bimanual data gloves to control virtual arms. Three applications trained bimanual reaching, grasping, hand opening. Assessments during 2-week baseline, weekly during intervention, at 3-month follow-up (FU): Goal Attainment Scale (GAS), Chedoke Arm and Hand Activity Inventory (CAHAI), Chedoke-McMaster Stroke Assessment (CMSA), Extended Barthel Index (EBI), Motor Activity Log (MAL). Functional magnetic resonance imaging scans (FMRI) before, immediately after treatment and at FU. P1 executed 5478 grasps (paretic arm). Improvements in CAHAI (+4) were maintained at FU. GAS changed to +1 post-test and +2 at FU. P2 executed 9835 grasps (paretic arm). CAHAI improvements (+13) were maintained at FU. GAS scores changed to -1 post-test and +1 at FU. MAL scores changed from 3.7 at pre-test to 5.5 post-test and 3.3 at FU. The VR-based intervention was feasible, safe, and intense. Adjustable application settings maintained training challenge and patient motivation. ADL-relevant UL functional improvements persisted at FU and were related to changed cortical activation patterns. Implications for Rehabilitation YouGrabber trains uni- and bimanual upper motor function. Its application is feasible, safe, and intense. The control of the virtual arms can be done in three main ways: (a) normal (b) virtual mirror therapy, or (c) virtual following. The mirroring feature provides an illusion of affected limb movements during the period when the affected upper limb (UL) is resting. The YouGrabber training led to ADL-relevant UL functional improvements that were still assessable 12 weeks after intervention finalization and were related to changed cortical activation patterns.

Inhalation gases or gaseous mediators as neuroprotectants for cerebral ischaemia.

PubMed

Sutherland, Brad A; Harrison, Joanne C; Nair, Shiva M; Sammut, Ivan A

2013-01-01

Ischaemic stroke is one of the leading causes of morbidity and mortality worldwide. While recombinant tissue plasminogen activator can be administered to produce thrombolysis and restore blood flow to the ischaemic brain, therapeutic benefit is only achieved in a fraction of the subset of patients eligible for fibrinolytic intervention. Neuroprotective therapies attempting to restrict the extent of brain injury following cerebral ischaemia have not been successfully translated into the clinic despite overwhelming pre-clinical evidence of neuroprotection. Therefore, an adequate treatment for the majority of acute ischaemic stroke patients remains elusive. In the stroke literature, the use of therapeutic gases has received relatively little attention. Gases such as hyperbaric and normobaric oxygen, xenon, hydrogen, helium and argon all possess biological effects that have shown to be neuroprotective in pre-clinical models of ischaemic stroke. There are significant advantages to using gases including their relative abundance, low cost and feasibility for administration, all of which make them ideal candidates for a translational therapy for stroke. In addition, modulating cellular gaseous mediators including nitric oxide, carbon monoxide, and hydrogen sulphide may be an attractive option for ischaemic stroke therapy. Inhalation of these gaseous mediators can also produce neuroprotection, but this strategy remains to be confirmed as a viable therapy for ischaemic stroke. This review highlights the neuroprotective potential of therapeutic gas therapy and modulation of gaseous mediators for ischaemic stroke. The therapeutic advantages of gaseous therapy offer new promising directions in breaking the translational barrier for ischaemic stroke.

TURBINE COOLING FLOW AND THE RESULTING DECREASE IN TURBINE EFFICIENCY

NASA Technical Reports Server (NTRS)

Gauntner, J. W.

1994-01-01

This algorithm has been developed for calculating both the quantity of compressor bleed flow required to cool a turbine and the resulting decrease in efficiency due to cooling air injected into the gas stream. Because of the trend toward higher turbine inlet temperatures, it is important to accurately predict the required cooling flow. This program is intended for use with axial flow, air-breathing jet propulsion engines with a variety of airfoil cooling configurations. The algorithm results have compared extremely well with figures given by major engine manufacturers for given bulk metal temperatures and cooling configurations. The program calculates the required cooling flow and corresponding decrease in stage efficiency for each row of airfoils throughout the turbine. These values are combined with the thermodynamic efficiency of the uncooled turbine to predict the total bleed airflow required and the altered turbine efficiency. There are ten airfoil cooling configurations and the algorithm allows a different option for each row of cooled airfoils. Materials technology is incorporated and requires the date of the first year of service for the turbine stator vane and rotor blade. The user must specify pressure, temperatures, and gas flows into the turbine. This program is written in FORTRAN IV for batch execution and has been implemented on an IBM 3080 series computer with a central memory requirement of approximately 61K of 8 bit bytes. This program was developed in 1980.

Effect of exhaust gas recirculation on emissions from a flame-tube combustor using Liquid Jet A fuel

NASA Technical Reports Server (NTRS)

Marek, C. J.; Tacina, R. R.

1976-01-01

The effects of uncooled exhaust gas recirculation as an inert diluent on emissions of oxides of nitrogen (NO + NO2) and on combustion efficiency were investigated. Ratios of recirculated combustion products to inlet airflow were varied from 10 to 80 percent by using an inlet air ejector nozzle. Liquid Jet A fuel was used. The flame-tube combustor was 10.2 cm in diameter. It was operated with and without a flameholder present. The combustor pressure was maintained constant at 0.5 MPa. The equivalence ratio was varied from 0.3 to 1.0. The inlet air temperature was varied from 590 to 800 K, and the reference velocity from 10 to 30 m/sec. Increasing the percent recirculation from 10 to 25 had the following effects: (1) the peak NOx emission was decreased by 37 percent, from 8 to 5 g NO2/kg fuel, at an inlet air temperature of 590 K and a reference velocity of 15 m/sec; (2) the combustion efficiency was increased, particularly at the higher equivalence ratios; and (3) for a high combustion efficiency of greater than 99.5 percent, the range of operation of the combustor was nearly doubled in terms of equivalence ratio. Increasing the recirculation from 25 to 50 percent did not change the emissions significantly.

Atherosclerosis and Stroke

MedlinePlus

... Stroke and atherosclerosis There are two types of ischemic stroke caused by blood clots, narrowing of blood vessels ... 2 What Is an Arteriovenous Malformation (AVM)? 3 Ischemic Strokes (Clots) 4 Hemorrhagic Strokes (Bleeds) 5 What You ...

The "Know Stroke" Campaign

MedlinePlus

... brain. There are two forms of stroke: an ischemic stroke occurs when a blood vessel supplying the brain ... Why is there a need to act fast? —Ischemic strokes, the most common type of stroke, can be ...

Stroke Self-efficacy Questionnaire: a Rasch-refined measure of confidence post stroke.

PubMed

Riazi, Afsane; Aspden, Trefor; Jones, Fiona

2014-05-01

Measuring self-efficacy during rehabilitation provides an important insight into understanding recovery post stroke. A Rasch analysis of the Stroke Self-efficacy Questionnaire (SSEQ) was undertaken to establish its use as a clinically meaningful and scientifically rigorous measure. One hundred and eighteen stroke patients completed the SSEQ with the help of an interviewer. Participants were recruited from local acute stroke units and community stroke rehabilitation teams. Data were analysed with confirmatory factor analysis conducted using AMOS and Rasch analysis conducted using RUMM2030 software. Confirmatory factor analysis and Rasch analyses demonstrated the presence of two separate scales that measure stroke survivors' self-efficacy with: i) self-management and ii) functional activities. Guided by Rasch analyses, the response categories of these two scales were collapsed from an 11-point to a 4-point scale. Modified scales met the expectations of the Rasch model. Items satisfied the Rasch requirements (overall and individual item fit, local response independence, differential item functioning, unidimensionality). Furthermore, the two subscales showed evidence of good construct validity. The new SSEQ has good psychometric properties and is a clinically useful assessment of self-efficacy after stroke. The scale measures stroke survivors' self-efficacy with self-management and activities as two unidimensional constructs. It is recommended for use in clinical and research interventions, and in evaluating stroke self-management interventions.

Generalized algebraic scene-based nonuniformity correction algorithm.

PubMed

Ratliff, Bradley M; Hayat, Majeed M; Tyo, J Scott

2005-02-01

A generalization of a recently developed algebraic scene-based nonuniformity correction algorithm for focal plane array (FPA) sensors is presented. The new technique uses pairs of image frames exhibiting arbitrary one- or two-dimensional translational motion to compute compensator quantities that are then used to remove nonuniformity in the bias of the FPA response. Unlike its predecessor, the generalization does not require the use of either a blackbody calibration target or a shutter. The algorithm has a low computational overhead, lending itself to real-time hardware implementation. The high-quality correction ability of this technique is demonstrated through application to real IR data from both cooled and uncooled infrared FPAs. A theoretical and experimental error analysis is performed to study the accuracy of the bias compensator estimates in the presence of two main sources of error.

A Compact, Multi-view Net Flux Radiometer for Future Uranus and Neptune Probes

NASA Technical Reports Server (NTRS)

Aslam, S.; Amato, M.; Atkinson, D. H.; Hewagama, T.; Jennings, D. E.; Nixon, C. A.; Mousis, O.

2017-01-01

A Net Flux Radiometer (NFR) is presented that can be included in an atmospheric structure instrument suite for future probe missions to the icy giants Uranus and Neptune. The baseline design has two spectral channels i.e., a solar channel (0.4-to-3.5 m) and a thermal channel (4-to-300 m). The NFR is capable of viewing five distinct viewing angles during the descent. Non-imaging Winston cones with band-pass filters are used for each spectral channel and to define a 5 angular acceptance. Uncooled thermopile detectors are used in each spectral channel and are read out using a custom radiation hard application specific integrated circuit (ASIC). The baseline design can easily be changed to increase the number of detector channels from two to seven.

Ischemic Stroke

MedlinePlus

A stroke is a medical emergency. There are two types - ischemic and hemorrhagic. Ischemic stroke is the most common type. It is usually ... are at risk for having a more serious stroke. Symptoms of stroke are Sudden numbness or weakness ...

A new theory of cryptogenic stroke and its relationship to patent foramen ovale; or, the puzzle of the missing extra risk.

PubMed

Eggers, Arnold E

2006-01-01

Cryptogenic stroke (or stroke of undetermined cause) is a common cause of stroke and is statistically associated with patent foramen ovale (PFO). The largest study of cryptogenic stroke is the Homma study, which is a sub-study of the WARSS trial; it produced the following data: cryptogenic stroke patients with and without PFO, when treated with either aspirin or warfarin, all had identical recurrence rates. This is puzzling because it seems as though there ought to have been some extra risk in one of the two groups under one of the two treatments. How could everything come out the same? A review of the epidemiology of cryptogenic stroke shows that, compared to patients with stroke of determined cause, cryptogenic stroke patients are a little younger and have lower doses of the usual risk factors (hypertension and diabetes mellitus) but more PFO. Cryptogenic strokes appear to be embolic strokes from an unknown source. A previously published article setting forth a hypothetical theory of stress-induced stroke was used to analyze these data. It is suggested that stress can induce episodic systemic platelet activation and hypercoagulability, which causes transient thrombus formation and subsequent embolization on both the arterial and venous sides of the circulation; the latter requires a PFO to cause a stroke (paradoxical embolism). The sum of these two mechanisms explains cryptogenic stroke. The PFO subset of cryptogenic stroke includes patients with both early and late stage disease who have an aggregate risk approximately equal to that of patients without PFO. Cryptogenic stroke is part of the disease of stress-induced cerebrovascular disease. Aspirin and warfarin have already been shown to be equally effective in secondary prevention of ischemic stroke.

Selection of NIR H2O absorption transitions for in-cylinder measurement of temperature in IC engines

NASA Astrophysics Data System (ADS)

Zhou, Xin; Liu, Xiang; Jeffries, Jay B.; Hanson, Ronald K.

2005-12-01

The water vapour spectrum in the 1.25-1.65 µm region is systematically analysed to find the best absorption transitions for sensitive measurement of in-cylinder gas temperature over short paths in an internal combustion engine. The strategy to select the optimum wavelength regions and absorption line combinations is developed for the time-varying pressures and temperatures expected during the compression portion of an engine cycle. We have identified 14 transitions of water vapour in this spectral region as promising for this application. From these transitions, 16 potential line pairs were considered for a wavelength-modulated absorption sensor for in-cylinder gas temperature during the compression stroke. Expected performance is modelled for the intake portion of two engine cycles that produce extreme temperature and pressure variations during compression.

Polarimetric Imaging System for Automatic Target Detection and Recognition

DTIC Science & Technology

2000-03-01

technique shown in Figure 4(b) can also be used to integrate polarizer arrays with other types of imaging sensors, such as LWIR cameras and uncooled...vertical stripe pattern in this φ image is caused by nonuniformities in the particular polarizer array used. 2. CIRCULAR POLARIZATION IMAGING USING

Athermal laser design.

PubMed

Bovington, Jock; Srinivasan, Sudharsanan; Bowers, John E

2014-08-11

This paper discusses circuit based and waveguide based athermalization schemes and provides some design examples of athermalized lasers utilizing fully integrated athermal components as an alternative to power hungry thermo-electric controllers (TECs), off-chip wavelength lockers or monitors with lookup tables for tunable lasers. This class of solutions is important for uncooled transmitters on silicon.

Hot ion plasma production in HIP-1 using water-cooled hollow cathodes

NASA Technical Reports Server (NTRS)

Reinmann, J. J.; Lauver, M. R.; Patch, R. W.; Layman, R. W.; Snyder, A.

1975-01-01

A steady-state ExB plasma was formed by applying a strong radially inward dc electric field near the mirror throats. Most of the results were for hydrogen, but deuterium and helium plasmas were also studied. Three water-cooled hollow cathodes were operated in the hot-ion plasma mode with the following results: (1) thermally emitting cathodes were not required to achieve the hot-ion mode; (2) steady-state operation (several minutes) was attained; (3) input powers greater than 40 kW were achieved; (4) cathode outside diameters were increased from 1.2 cm (uncooled) to 4.4 cm (water-cooled); (5) steady-state hydrogen plasma with ion temperatures from 185 to 770 eV and electron temperatures from 5 to 21 eV were produced. Scaling relations were empirically obtained for discharge current, ion temperature, electron temperature, and relative ion density as a function of hydrogen gas feed rate, magnetic field, and cathode voltage. Neutrons were produced from deuterium plasma, but it was not established whether thay came from the plasma volume or from the electrode surfaces.

Prediction of post-stroke dementia using NINDS-CSN 5-minute neuropsychology protocol in acute stroke.

PubMed

Lim, Jae-Sung; Oh, Mi Sun; Lee, Ju-Hun; Jung, San; Kim, Chulho; Jang, Min Uk; Lee, Sang-Hwa; Kim, Yeo Jin; Kim, Yerim; Park, Jaeseol; Kang, Yeonwook; Yu, Kyung-Ho; Lee, Byung-Chul

2017-05-01

The National Institute of Neurological Disease and Stroke-Canadian Stroke Network (NINDS-CSN) 5-minute neuropsychology protocol consists of only verbal tasks, and is proposed as a brief screening method for vascular cognitive impairment. We evaluated its feasibility within two weeks after stroke and ability to predict the development of post-stroke dementia (PSD) at 3 months after stroke. We prospectively enrolled subjects with ischemic stroke within seven days of symptom onset who were consecutively admitted to 12 university hospitals. Neuropsychological assessments using the NINDS-CSN 5-minute and 60-minute neuropsychology protocols were administered within two weeks and at 3 months after stroke onset, respectively. PSD was diagnosed with reference to the American Heart Association/American Stroke Association statement, requiring deficits in at least two cognitive domains. Of 620 patients, 512 (82.6%) were feasible for the NINDS-CSN 5-minute protocol within two weeks after stroke. The incidence of PSD was 16.2% in 308 subjects who had completed follow-up at 3 months after stroke onset. The total score of the NINDS-CSN 5-minute protocol differed significantly between those with and without PSD (4.0 ± 2.7, 7.4 ± 2.7, respectively; p < 0.01). A cut-off value of 6/7 showed reasonable discriminative power (sensitivity 0.82, specificity 0.67, AUC 0.74). The NINDS-CSN 5-minute protocol score was a significant predictor for PSD (adjusted odds ratio 6.32, 95% CI 2.65-15.05). The NINDS-CSN 5-minute protocol is feasible to evaluate cognitive functions in patients with acute ischemic stroke. It might be a useful screening method for early identification of high-risk groups for PSD.

Physiotherapy after Stroke in Ireland: A Qualitative Insight into the Patients' and Physiotherapists' Experience

ERIC Educational Resources Information Center

Galvin, Rose; Cusack, Tara; Stokes, Emma

2009-01-01

The study aimed to examine the experience of inpatient physiotherapy intervention delivered after stroke in Ireland from two different perspectives: that of the person with stroke and that of the physiotherapist. A qualitative study was conducted involving semistructured interviews with 10 people with stroke and two focus groups with 10 senior…

Assimilation of Web-Based Urgent Stroke Evaluation: A Qualitative Study of Two Networks

PubMed Central

Mathiassen, Lars; Switzer, Jeffrey A; Adams, Robert J

2014-01-01

Background Stroke is a leading cause of death and serious, long-term disability across the world. Urgent stroke care treatment is time-sensitive and requires a stroke-trained neurologist for clinical diagnosis. Rural areas, where neurologists and stroke specialists are lacking, have a high incidence of stroke-related death and disability. By virtually connecting emergency department physicians in rural hospitals to regional medical centers for consultations, specialized Web-based stroke evaluation systems (telestroke) have helped address the challenge of urgent stroke care in underserved communities. However, many rural hospitals that have deployed telestroke have not fully assimilated this technology. Objective The objective of this study was to explore potential sources of variations in the utilization of a Web-based telestroke system for urgent stroke evaluation and propose a telestroke assimilation model to improve stroke care performance. Methods An exploratory, qualitative case study of two telestroke networks, each comprising an academic stroke center (hub) and connected rural hospitals (spokes), was conducted. Data were collected from 50 semistructured interviews with 40 stakeholders, telestroke usage logs from 32 spokes, site visits, published papers, and reports. Results The two networks used identical technology (called Remote Evaluation of Acute isCHemic stroke, REACH) and were of similar size and complexity, but showed large variations in telestroke assimilation across spokes. Several observed hub- and spoke-related characteristics can explain these variations. The hub-related characteristics included telestroke institutionalization into stroke care, resources for the telestroke program, ongoing support for stroke readiness of spokes, telestroke performance monitoring, and continuous telestroke process improvement. The spoke-related characteristics included managerial telestroke championship, stroke center certification, dedicated telestroke coordinator, stroke committee of key stakeholders, local neurological expertise, and continuous telestroke process improvement. Conclusions Rural hospitals can improve their stroke readiness with use of telestroke systems. However, they need to integrate the technology into their stroke delivery processes. A telestroke assimilation model may improve stroke care performance. PMID:25601232

Uncooled Terahertz real-time imaging 2D arrays developed at LETI: present status and perspectives

NASA Astrophysics Data System (ADS)

Simoens, François; Meilhan, Jérôme; Dussopt, Laurent; Nicolas, Jean-Alain; Monnier, Nicolas; Sicard, Gilles; Siligaris, Alexandre; Hiberty, Bruno

2017-05-01

As for other imaging sensor markets, whatever is the technology, the commercial spread of terahertz (THz) cameras has to fulfil simultaneously the criteria of high sensitivity and low cost and SWAP (size, weight and power). Monolithic silicon-based 2D sensors integrated in uncooled THz real-time cameras are good candidates to meet these requirements. Over the past decade, LETI has been studying and developing such arrays with two complimentary technological approaches, i.e. antenna-coupled silicon bolometers and CMOS Field Effect Transistors (FET), both being compatible to standard silicon microelectronics processes. LETI has leveraged its know-how in thermal infrared bolometer sensors in developing a proprietary architecture for THz sensing. High technological maturity has been achieved as illustrated by the demonstration of fast scanning of large field of view and the recent birth of a commercial camera. In the FET-based THz field, recent works have been focused on innovative CMOS read-out-integrated circuit designs. The studied architectures take advantage of the large pixel pitch to enhance the flexibility and the sensitivity: an embedded in-pixel configurable signal processing chain dramatically reduces the noise. Video sequences at 100 frames per second using our 31x31 pixels 2D Focal Plane Arrays (FPA) have been achieved. The authors describe the present status of these developments and perspectives of performance evolutions are discussed. Several experimental imaging tests are also presented in order to illustrate the capabilities of these arrays to address industrial applications such as non-destructive testing (NDT), security or quality control of food.

Passive cavity surface-emitting lasers: option of temperature-insensitive lasing wavelength for uncooled dense wavelength division multiplexing systems

NASA Astrophysics Data System (ADS)

Shchukin, V. A.; Ledentsov, N. N.; Slight, T.; Meredith, W.; Gordeev, N. Y.; Nadtochy, A. M.; Payusov, A. S.; Maximov, M. V.; Blokhin, S. A.; Blokhin, A. A.; Zadiranov, Yu. M.; Maleev, N. A.; Ustinov, V. M.; Choquette, K. D.

2016-03-01

A concept of passive cavity surface-emitting laser is proposed aimed to control the temperature shift of the lasing wavelength. The device contains an all-semiconductor bottom distributed Bragg reflector (DBR), in which the active medium is placed, a dielectric resonant cavity and a dielectric top DBR, wherein at least one of the dielectric materials has a negative temperature coefficient of the refractive index, dn/dT < 0. This is shown to be the case for commonly used dielectric systems SiO2/TiO2 and SiO2/Ta2O5. Two SiO2/TiO2 resonant structures having a cavity either of SiO2 or TiO2 were deposited on a substrate, their optical power reflectance spectra were measured at various temperatures, and refractive index temperature coefficients were extracted, dn/dT = 0.0021 K-1 for SiO2 and dn/dT = -0.0092 K-1 for TiO2. Using such dielectric materials allows designing passive cavity surface-emitting lasers having on purpose either positive, or zero, or negative temperature shift of the lasing wavelength dλ/dT. A design for temperature-insensitive lasing wavelength (dλ/dT = 0) is proposed. Employing devices with temperature-insensitive lasing wavelength in wavelength division multiplexing systems may allow significant reducing of the spectral separation between transmission channels and an increase in number of channels for a defined spectral interval enabling low cost energy efficient uncooled devices.

40 CFR 90.107 - Application for certification.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., manufacturers of two-stroke lawnmower engines must submit with their application for a certificate of conformity: (i) For model year 1997, information establishing the highest number of two-stroke lawnmower engines... production and projected production for the current year. (2) In model year 1997, two-stroke lawnmower engine...

40 CFR 90.107 - Application for certification.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., manufacturers of two-stroke lawnmower engines must submit with their application for a certificate of conformity: (i) For model year 1997, information establishing the highest number of two-stroke lawnmower engines... production and projected production for the current year. (2) In model year 1997, two-stroke lawnmower engine...

40 CFR 90.107 - Application for certification.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., manufacturers of two-stroke lawnmower engines must submit with their application for a certificate of conformity: (i) For model year 1997, information establishing the highest number of two-stroke lawnmower engines... production and projected production for the current year. (2) In model year 1997, two-stroke lawnmower engine...

40 CFR 90.107 - Application for certification.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., manufacturers of two-stroke lawnmower engines must submit with their application for a certificate of conformity: (i) For model year 1997, information establishing the highest number of two-stroke lawnmower engines... production and projected production for the current year. (2) In model year 1997, two-stroke lawnmower engine...

Effects of comprehensive education protocol in decreasing pre-hospital stroke delay among Chinese urban community population.

PubMed

Chen, Shengyun; Sun, Haixin; Zhao, Xingquan; Fu, Paul; Yan, Wang; Yilong, Wang; Hongyan, Jia; Yan, Zhang; Wenzhi, Wang

2013-06-01

Studies have shown that awareness of early stroke symptoms and the use of ambulances are two important factors in decreasing pre-hospital stroke delay. The purpose of this study is to evaluate a comprehensive educational stroke protocol in improving stroke response times. Two urban communities in Beijing (population ≍50 000), matched in economic status and geography, were enrolled in this study. A comprehensive educational protocol, which included public lectures and distribution of instructive material for the community and its medical staff, was implemented from August 2008 to December 2010. Surveillance of new onset stroke in both communities was carried out during the same period. Pre-hospital delay time and percentage of patients using emergency medical services (EMS) were compared between the two communities. After comprehensive educational protocol, we found that: (i) pre-hospital delay (time from stroke symptom onset to hospital arrival) decreased from 180 to 79 minutes, (ii) the proportion of patients arriving within three hours of stroke onset increased from 55·8% to 80·4%, (iii) pre-hospital delay of stroke patients with symptoms of paralysis, numbness, and speech impediments was decreased, and (iv) the proportion of stroke patients calling for EMS increased from 50·4% to 60·7%. The comprehensive educational stroke protocol was significantly effective in decreasing pre-hospital stroke delay.

Design of a Wideband Radio Telescope

NASA Technical Reports Server (NTRS)

Imbriale, William A.; Weinreb, Sander; Mani, Handi

2007-01-01

A wideband Radio Telescope is being designed for use in the Goldstone Apple Valley Radio Telescope program. It uses an existing 34-meter antenna retrofitted with a tertiary offset mirror placed at the apex of the main reflector. It can be rotated to use two feeds that cover the 1.2 to 14 GHz band. The feed for 4.0 to 14.0 GHz is a cryogenically cooled commercially available open boundary quadridge horn from ETS-Lindgren. Coverage from 1.2 to 4.0 GHz is provided by an un-cooled scaled version of the same feed. The performance is greater than 40% over most of the band and greater than 55%from 6 to 13.5 GHz.

U.S. market for infrared thermography equipment

NASA Astrophysics Data System (ADS)

Fulop, Gabor F.

1995-03-01

The market for infrared thermography is undergoing dramatic changes. Focal plane array technologies previously dominated by the military are being opened up to the commercial sector, new uncooled technologies are advancing rapidly and entirely new applications are emerging. Maxtech International has carried out its second in-depth analysis of these markets within two years. In 1994, the U.S. market for commercial (and dual-use) infrared thermography equipment reached 100 million and is expected to grow to 250 million by 1999. As part of the analysis, a survey of over 3,900 users of infrared thermography equipment has been completed. Included are segmentation by end-user industry and expected spending projections in various market segments.

What to Know – and Do! – About Stroke | NIH MedlinePlus the Magazine

MedlinePlus

... function. There are two forms of stroke: an ischemic stroke occurs when a blood vessel supplying the brain ... Why is there a need to act fast?— Ischemic strokes, the most common type of stroke, can be ...

The propagation speed of a positive lightning return stroke

NASA Technical Reports Server (NTRS)

Idone, Vincent P.; Orville, Richard E.; Mach, Douglas M.; Rust, W. David

1987-01-01

The first direct determination of the propagation speed of a lightning return stroke lowering positive charge to ground has been made. This stroke was the third of eight otherwise negative strokes in a triggered lightning flash initiated at the Kennedy Space Center, FL. Two independent optical systems, one photographic and the other photoelectric, yielded common recordings for the third and fourth strokes; the respective two-dimensional return stroke propagation speeds were 1.0 vs 0.93 x 10 to the 8th m/s for the positive (third) stroke and 1.0 vs 1.0 x 10 to the 8th m/s for the fourth stroke. Using fast electric-field data, the positive stroke peak current was estimated to be 21 kA. Photoelectric data only yielded propagation speeds of 1.4, 1.6, 1.2, 1.3, 1.0 and 0.90 x 10 to the 8th m/s for the first, second and fifth through eighth return strokes, respectively.

A systematic review of perceived barriers and motivators to physical activity after stroke.

PubMed

Nicholson, Sarah; Sniehotta, Falko F; van Wijck, Frederike; Greig, Carolyn A; Johnston, Marie; McMurdo, Marion E T; Dennis, Martin; Mead, Gillian E

2013-07-01

Physical fitness is impaired after stroke, may contribute to disability, yet is amenable to improvement through regular physical activity. To facilitate uptake and maintenance of physical activity, it is essential to understand stroke survivors' perceived barriers and motivators. Therefore, we undertook a systematic review of perceived barriers and motivators to physical activity after stroke. Electronic searches of EMBASE, Medline, CINAHL, and PsychInfo were performed. We included peer-reviewed journal articles, in English, between 1 January 1966 and 30 August 2010 reporting stroke survivors' perceived barriers and motivators to physical activity. Searches identified 73,807 citations of which 57 full articles were retrieved. Six articles were included, providing data on 174 stroke survivors (range 10 to 83 per article). Two reported barriers and motivators, two reported only motivators, and two reported only barriers. Five were qualitative articles and one was quantitative. The most commonly reported barriers were lack of motivation, environmental factors (e.g. transport), health concerns, and stroke impairments. The most commonly reported motivators were social support and the need to be able to perform daily tasks. This review has furthered our understanding of the perceived barriers and motivators to physical activity after a stroke. This review will enable the development of tailored interventions to target barriers, while building upon perceived motivators to increase and maintain stroke survivors' physical activity. © 2012 The Authors. International Journal of Stroke © 2012 World Stroke Organization.

Low temperature fabrication of VO x thin films for uncooled IR detectors by direct current reactive magnetron sputtering method

NASA Astrophysics Data System (ADS)

Dai, Jun; Wang, Xingzhi; He, Shaowei; Huang, Ying; Yi, Xinjian

2008-03-01

Vanadium oxide films have been fabricated on Si3N4-film-coated silicon substrates by direct current reactive magnetron sputtering method. Conditions of deposition are optimized making use of parameters such as sputtering time, dc power, oxygen partial pressure and substrate temperature. X-ray diffraction indicates that the film is a mixture of VO2, V2O3, and V3O5. Four-probe measurement shows that the VOx thin film owns high temperature coefficient of resistance (TCR ∼-2.05%/°C) and suitable square resistance 18.40 kΩ/□ (measured at 25 °C), indicating it is a well candidate material for uncooled IR detectors. In addition, IR absorption in the wavelength of 2-16 μm has been characterized. It is worth noting that the films are sputtered at a relatively low temperature of 210 °C in a controlled Ar/O2 atmosphere. Compared to traditional craft, this method needs no post-anneal at high temperature (400-500 °C).

A compact lightweight Earth horizon sensor using an uncooled infrared bolometer

NASA Astrophysics Data System (ADS)

Marchese, Linda E.; Thomas, Paul; Pope, Timothy D.; Asselin, Daniel; Jerominek, Hubert

2007-06-01

A compact, lightweight Earth horizon sensor has been designed based on uncooled infrared microbolometer array technology developed at INO. The design has been optimized for use on small satellites in Low Earth Orbits. The sensor may be used either as an attitude sensor or as an atmospheric limb detector. Various configurations may be implemented for both spinning and 3-axis stabilized satellites. The core of the sensor is the microbolometer focal plane array equipped with 256 x 1 VO x thermistor pixels with a pitch of 52 μm. The optics consists of a single Zinc Selenide lens with a focal length of 39.7 mm. The system's F-number is 3.8 and the detector limited Noise Equivalent Temperature Difference is estimated to be 0.75 K at 300 K for the 14 - 16 μm wavelength range. A single-sensor configuration will have a mass of less than 300g, a volume of 125 cm 3 and a power consumption of 600 mW, making it well-suited for small satellite missions.

Characterization of fluid physics effects on cardiovascular response to microgravity (G-572)

NASA Technical Reports Server (NTRS)

Pantalos, George M.; Bennett, Thomas E.; Sharp, M. Keith; Woodruff, Stewart; Oleary, Sean; Gillars, Kevin; Lemon, Mark; Sojka, Jan

1995-01-01

The investigation of cardiovascular adaptation to space flight has seen substantial advancement in the last several years. In-flight echocardiographic measurements of astronaut cardiac function on the Space Shuttle have documented an initial increase, followed by a progressive reduction in both left ventricular volume index and stroke volume with a compensatory increase in heart rate to maintain cardiac output. To date, the reduced cardiac size and stroke volume have been presumed to be the consequence of the reduction in circulating fluid volume within a few days after orbital insertion. However, no specific mechanism for the reduced stroke volume has been identified. The following investigation proposes the use of a hydraulic model of the cardiovascular system to examine the possibility that the observed reduction in stroke volume may, in part, be related to fluid physics effects on heart function. The automated model is being prepared to fly as a Get Away Special (GAS) payload within the next year.

Aerodynamic performance of high turning core turbine vanes in a two dimensional cascade

NASA Technical Reports Server (NTRS)

Schwab, J. R.

1982-01-01

Experimental and theoretical aerodynamic performance data are presented for four uncooled high turning core turbine vanes with exit angles of 74.9, 75.0, 77.5, and 79.6 degrees in a two dimensional cascade. Data for a more conservative 67.0 degree vane are included for comparison. Correction of the experimental aftermix kinetic energy losses to a common 0.100 centimeter trailing edge thickness yields a linear trend of increased loss from 0.020 to 0.025 as the vane exit angle increases from 67.0 to 79.6 degrees. The theoretical losses show a similar trend. The experimental and theoretical vane surface velocity distributions generally agree within approximately five percent, although the suction surface theoretical velocities are generally higher than the experimental velocities as the vane exit angle increases.

Photoelectric return-stroke velocity and peak current estimates in natural and triggered lightning

NASA Technical Reports Server (NTRS)

Mach, Douglas M.; Rust, W. David

1989-01-01

Two-dimensional photoelectric return stroke velocities from 130 strokes are presented, including 86 negative natural, 41 negative triggered, one positive triggered, and two positive natural return strokes. For strokes starting near the ground and exceeding 500 m in length, the average velocity is 1.3 + or - 0.3 X 10 to the 8th m/s for natural return strokes and 1.2 + or - 0.3 X 10 to the 8th m/s for triggered return strokes. For strokes with lengths less than 500 m, the average velocities are slightly higher. Using the transmission line model (TLM), the shortest segment one-dimensional return stroke velocity, and either the maximum or plateau electric field, it is shown that natural strokes have a peak current distribution that is lognormal with a median value of 16 kA (maximum E) or 12 kA (plateau E). Triggered lightning has a medium peak current value of 21 kA (maximum E) or 15 kA (plateau E). Correlations are found between TLM peak currents and velocities for triggered and natural subsequent return strokes, but not between TLM peak currents and natural first return stroke velocities.

Hemorrhagic Stroke

MedlinePlus

A stroke is a medical emergency. There are two types - ischemic and hemorrhagic. Hemorrhagic stroke is the less common type. It happens when ... an artery wall that breaks open. Symptoms of stroke are Sudden numbness or weakness of the face, ...

Stroke Connection Magazine

MedlinePlus

... for the decision-making process required when it’s time to leave the hospital. What to Expect in Stroke Rehab Following a stroke, about two-thirds of survivors receive some type rehabilitation. In this second of our two-art series, we want to alleviate some of the mystery, ...

Using the Two-Stroke Engine to Develop Technological Literacy

ERIC Educational Resources Information Center

Preble, Brian C.

2018-01-01

The two-stroke engine is an engineering marvel that has been incorporated into many aspects of modern-day life. While many seek to eliminate the two-stroke, others seek to revive this simple and effective power plant, aiming to make it more environmentally friendly and fuel-efficient. If successful, improvements could be far-reaching and…

Swap intensified WDR CMOS module for I2/LWIR fusion

NASA Astrophysics Data System (ADS)

Ni, Yang; Noguier, Vincent

2015-05-01

The combination of high resolution visible-near-infrared low light sensor and moderate resolution uncooled thermal sensor provides an efficient way for multi-task night vision. Tremendous progress has been made on uncooled thermal sensors (a-Si, VOx, etc.). It's possible to make a miniature uncooled thermal camera module in a tiny 1cm3 cube with <1W power consumption. For silicon based solid-state low light CCD/CMOS sensors have observed also a constant progress in terms of readout noise, dark current, resolution and frame rate. In contrast to thermal sensing which is intrinsic day&night operational, the silicon based solid-state sensors are not yet capable to do the night vision performance required by defense and critical surveillance applications. Readout noise, dark current are 2 major obstacles. The low dynamic range at high sensitivity mode of silicon sensors is also an important limiting factor, which leads to recognition failure due to local or global saturations & blooming. In this context, the image intensifier based solution is still attractive for the following reasons: 1) high gain and ultra-low dark current; 2) wide dynamic range and 3) ultra-low power consumption. With high electron gain and ultra low dark current of image intensifier, the only requirement on the silicon image pickup device are resolution, dynamic range and power consumption. In this paper, we present a SWAP intensified Wide Dynamic Range CMOS module for night vision applications, especially for I2/LWIR fusion. This module is based on a dedicated CMOS image sensor using solar-cell mode photodiode logarithmic pixel design which covers a huge dynamic range (> 140dB) without saturation and blooming. The ultra-wide dynamic range image from this new generation logarithmic sensor can be used directly without any image processing and provide an instant light accommodation. The complete module is slightly bigger than a simple ANVIS format I2 tube with <500mW power consumption.

ACUTE BEHAVORIAL EFFECTS FROM EXPOSURE TO TWO-STROKE ENGINE EXHAUST

EPA Science Inventory

Benefits of changing from two-stroke to four-stroke engines (and other remedial requirements) can be evaluated (monetized) from the standpoint of acute behavioral effects of human exposure to exhaust from these engines. The monetization process depends upon estimates of the magn...

Cardiopulmonary exercise testing early after stroke using feedback-controlled robotics-assisted treadmill exercise: test-retest reliability and repeatability.

PubMed

Stoller, Oliver; de Bruin, Eling D; Schindelholz, Matthias; Schuster-Amft, Corina; de Bie, Rob A; Hunt, Kenneth J

2014-10-11

Exercise capacity is seriously reduced after stroke. While cardiopulmonary assessment and intervention strategies have been validated for the mildly and moderately impaired populations post-stroke, there is a lack of effective concepts for stroke survivors suffering from severe motor limitations. This study investigated the test-retest reliability and repeatability of cardiopulmonary exercise testing (CPET) using feedback-controlled robotics-assisted treadmill exercise (FC-RATE) in severely motor impaired individuals early after stroke. 20 subjects (age 44-84 years, <6 month post-stroke) with severe motor limitations (Functional Ambulatory Classification 0-2) were selected for consecutive constant load testing (CLT) and incremental exercise testing (IET) within a powered exoskeleton, synchronised with a treadmill and a body weight support system. A manual human-in-the-loop feedback system was used to guide individual work rate levels. Outcome variables focussed on standard cardiopulmonary performance parameters. Relative and absolute test-retest reliability were assessed by intraclass correlation coefficients (ICC), standard error of the measurement (SEM), and minimal detectable change (MDC). Mean difference, limits of agreement, and coefficient of variation (CoV) were estimated to assess repeatability. Peak performance parameters during IET yielded good to excellent relative reliability: absolute peak oxygen uptake (ICC =0.82), relative peak oxygen uptake (ICC =0.72), peak work rate (ICC =0.91), peak heart rate (ICC =0.80), absolute gas exchange threshold (ICC =0.91), relative gas exchange threshold (ICC =0.88), oxygen cost of work (ICC =0.87), oxygen pulse at peak oxygen uptake (ICC =0.92), ventilation rate versus carbon dioxide output slope (ICC =0.78). For these variables, SEM was 4-13%, MDC 12-36%, and CoV 0.10-0.36. CLT revealed high mean differences and insufficient test-retest reliability for all variables studied. This study presents first evidence on reliability and repeatability for CPET in severely motor impaired individuals early after stroke using a feedback-controlled robotics-assisted treadmill. The results demonstrate good to excellent test-retest reliability and appropriate repeatability for the most important peak cardiopulmonary performance parameters. These findings have important implications for the design and implementation of cardiovascular exercise interventions in severely impaired populations. Future research needs to develop advanced control strategies to enable the true limit of functional exercise capacity to be reached and to further assess test-retest reliability and repeatability in larger samples.

The two-stroke poppet valve engine. Part 2: Numerical investigations of intake and exhaust flow behaviour

NASA Astrophysics Data System (ADS)

Kamili Zahidi, M.; Razali Hanipah, M.

2017-10-01

A two-stroke poppet valve engine is developed to overcome the common problems in conventional two-stroke engine designs. However, replacing piston control port with poppet valve will resulted different flow behaviour. This paper presents the model and simulation result of three-dimensional (3D) port flow investigation of a two-stroke poppet valve engine. The objective of the investigation is to conduct a numerical investigation on port flow performance of two-stroke poppet valve engine and compare the results obtained from the experimental investigation. The model is to be used for the future numerical study of the engine. The volume flow rate results have been compared with the results obtained experimentally as presented in first part of this paper. The model has shown good agreement in terms of the flow rate at initial and final valve lifts but reduced by about 50% during half-lift region.

Lightning-channel morphology by return-stroke radiation field waveforms

NASA Technical Reports Server (NTRS)

Willett, J. C.; Le Vine, D. M.; Idone, V. P.

1995-01-01

Simultaneous video and wideband electric field recordings of 32 cloud-to-ground lightning flashes in Florida were analyzed to show the formation of new channels to ground can be detected by examination of the return-stroke radiation fields alone. The return-stroke E and dE/dt waveforms were subjectively classified according to their fine structure. Then the video images were examined field by field to identify each waveform with a visible channel to ground. Fifty-five correlated waveforms and channel images were obtained. Of these, all 34 first-stroke waveforms (multiple jagged E peaks, noisy dE/dt), 8 of which were not radiated by the chronologically first stroke in the flash, came from new channels to ground (not previously seen on video). All 18 subsequent-stroke waveforms (smoothly rounded E and quiet dE/dt after initial peak) were radiated by old channels (illuminated by a previous stroke). Two double-ground waveforms (two distinct first-return-stroke pulses separated by tens of microseconds or less) coincided with video fields showing two new channels. One `anomalous-stroke' waveform (beginning like a first stroke and ending like a subsequent) was produced by a new channel segment to ground branching off an old channel. This waveform classification depends on the presence or absence of high-frequency fine structure. Fourier analysis shows that first-stroke waveforms contain about 18 dB more spectral power in the frequency interval from 500 kHz to at least 7 MHz than subsequent-stroke waveforms for at least 13 microseconds after the main peak.

A Typology to Explain Changing Social Networks Post Stroke.

PubMed

Northcott, Sarah; Hirani, Shashivadan P; Hilari, Katerina

2018-05-08

Social network typologies have been used to classify the general population but have not previously been applied to the stroke population. This study investigated whether social network types remain stable following a stroke, and if not, why some people shift network type. We used a mixed methods design. Participants were recruited from two acute stroke units. They completed the Stroke Social Network Scale (SSNS) two weeks and six months post stroke and in-depth interviews 8-15 months following the stroke. Qualitative data was analysed using Framework Analysis; k-means cluster analysis was applied to the six-month data set. Eighty-seven participants were recruited, 71 were followed up at six months, and 29 completed in-depth interviews. It was possible to classify all 29 participants into one of the following network types both prestroke and post stroke: diverse; friends-based; family-based; restricted-supported; restricted-unsupported. The main shift that took place post stroke was participants moving out of a diverse network into a family-based one. The friends-based network type was relatively stable. Two network types became more populated post stroke: restricted-unsupported and family-based. Triangulatory evidence was provided by k-means cluster analysis, which produced a cluster solution (for n = 71) with comparable characteristics to the network types derived from qualitative analysis. Following a stroke, a person's social network is vulnerable to change. Explanatory factors for shifting network type included the physical and also psychological impact of having a stroke, as well as the tendency to lose contact with friends rather than family.

Relationship between QT Interval Dispersion in acute stroke and stroke prognosis: A Systematic Review

PubMed Central

Lederman, Yitzchok S.; Balucani, Clotilde; Lazar, Jason; Steinberg, Leah; Gugger, James; Levine, Steven R.

2014-01-01

Background QT dispersion (QTd) has been proposed as an indirect ECG measure of heterogeneity of ventricular repolarization. The predictive value of QTd in acute stroke remains controversial. We aimed to clarify the relationship between QTd and acute stroke and stroke prognosis. Methods A systematic review of the literature was performed using pre-specified medical subjects heading (MeSH) terms, Boolean logic and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Eligible studies (a) included ischemic or hemorrhagic stroke and (b) provided QTd measurements. Results Two independent reviewers identified 553 publications. Sixteen articles were included in the final analysis. There were a total of 888 stroke patients: 59% ischemic and 41% hemorrhagic. There was considerable heterogeneity in study design, stroke subtypes, ECG assessment-time, control groups and comparison groups. Nine studies reported a significant association between acute stroke and baseline QTd. Two studies reported that QTd increases are specifically related to hemorrhagic strokes, involvement of the insular cortex, right-side lesions, larger strokes, and increases in 3, 4-dihydroxyphenylethylene glycol in hemorrhagic stroke. Three studies reported QTd to be an independent predictor of stroke mortality. One study each reported increases in QTd in stroke patients who developed ventricular arrhythmias and cardiorespiratory compromise. Conclusions There are few well-designed studies and considerable variability in study design in addressing the significance of QTd in acute stroke. Available data suggest that stroke is likely to be associated with increased QTd. While some evidence suggests a possible prognostic role of QTd in stroke, larger and well-designed studies need to confirm these findings. PMID:25282188

Flex-Fuel Two-Stroke Snowmobile: Development of a Flex-Fuel, Two-Stroke, Direct-Injection Snowmobile for Use in the Clean Snowmobile Challenge and National Parks

DOT National Transportation Integrated Search

2009-09-01

The University of Idaho's entry into the 2009 SAE Clean Snowmobile Challenge (CSC) was a semi-direct-injection (SDI) two-stroke powered REV-XP snowmobile modified to use flex fuel. The flex fuel engine produces stock engine power on any blend of etha...

[Association Between SNP rs6007897 of CELSR1 and Acute Ischemic Stroke in Western China Han Population: a Case-control Study].

PubMed

Qin, Feng-qin; Yu, Li-hua; Hu, Wen-ting; Guo, Jian; Chen, Ning; Guo, Jiang; Fang, Jing-huan; He, Li

2015-07-01

To investigate the relationship between single nucleotide polymorphism (SNP) rs6007897 of CELSR1 and acute ischemic stroke in Western China Han population. All subjects (759 acute ischemic stroke patients and 786 controls) were genotyped using ligation detection reaction (LDR). We analyzed the differences between SNP rs6007897 genotypes and allele frequencies between two groups. Two genotypes (AA, AG) of rs6007897 were found in both stroke and control group. There was no statistically significance between two groups about genotype and allele frequency. After adjusting for risk factors, we found there was no significant association between rs6007897 and ischemic stroke CP = 0.797, odds ratio (OR) = 0.886, 95% confidence interval (CI) = 0.352-2.227). SNP rs6007897 of CELSR1 was not significantly associated with ischemic stroke in Western China Han population.

Small Engine Repair. Two-Stroke and Four-Stroke Cycle.

ERIC Educational Resources Information Center

Hires, Bill; And Others

This curriculum guide is intended to assist persons teaching a course in repairing two- and four-stroke cycle small engines. Addressed in the individual units of instruction are the following topics: safety, tools, fasteners, and measurement techniques; basic small engine theory (engine identification and inspection, basic engine principles and…

Fast Uncooled Low Density FPA of VPD PbSe for Applications in Hyperspectral Imagery

DTIC Science & Technology

2009-10-01

Marañosa (ITM-CIDA). Area de Optronica y Acustica Unidad de Sensores y Micro-Nano Tecnologia Arturo Soria, 289 E-28033 Madrid, Spain ABSTRACT...ADDRESS(ES) Instituto Tecnologico de la Marañosa (ITM-CIDA). Area de Optronica y Acustica Unidad de Sensores y Micro-Nano Tecnologia Arturo Soria, 289

Passive athermalization of doublets in 8-13 micron waveband

NASA Astrophysics Data System (ADS)

Schuster, Norbert

2014-10-01

Passive athermalization of lenses has become a key-technology for automotive and other outdoor applications using modern uncooled 25, 17 and 12 micron pixel pitch bolometer arrays. Typical pixel counts for thermal imaging are 384x288 (qVGA), 640x480 (VGA), and 1024x768 (XGA). Two lens arrangements (called Doublets) represent a cost effective way to satisfy resolution requirements of these detectors with F-numbers 1.4 or faster. Thermal drift of index of refraction and the geometrical changes (in lenses and housing) versus temperature defocus the initial image plane from the detector plane. The passive athermalization restricts this drop of spatial resolution in a wide temperature range (typically -40°C…+80°C) to an acceptable value without any additional external refocus. In particular, lenses with long focal lengths and high apertures claim athermalization. A careful choice of lens and housing materials and a sophistical dimensioning lead to three different principles of passivation: The Passive Mechanical Athermalization (PMA) shifts the complete lens cell, the Passive Optical and Mechanical Athermalization (POMA) shifts only one lens inside the housing, the Passive Optical Athermalization (POA) works without any mechanism. All three principles will be demonstrated for a typical narrow-field lens (HFOV about 12°) with high aperture (aperture based F-number 1.3) for the actual uncooled reference detector (17micron VGA). Six design examples using different combinations of lens materials show the impact on spatial lens resolution, on overall length, and on weight. First order relations are discussed. They give some hints for optimization solutions. Pros and cons of different passive athermalization principles are evaluated in regards of housing design, availability of materials and costing. Examples with a convergent GASIR®1-lens in front distinguish by best resolution, short overall length, and lowest weight.

Deposition stress effects on thermal barrier coating burner rig life

NASA Technical Reports Server (NTRS)

Watson, J. W.; Levine, S. R.

1984-01-01

A study of the effect of plasma spray processing parameters on the life of a two layer thermal barrier coating was conducted. The ceramic layer was plasma sprayed at plasma arc currents of 900 and 600 amps onto uncooled tubes, cooled tubes, and solid bars of Waspalloy in a lathe with 1 or 8 passes of the plasma gun. These processing changes affected the residual stress state of the coating. When the specimens were tested in a Mach 0.3 cyclic burner rig at 1130 deg C, a wide range of coating lives resulted. Processing factors which reduced the residual stress state in the coating, such as reduced plasma temperature and increased heat dissipation, significantly increased coating life.

Deposition stress effects on the life of thermal barrier coatings on burner rigs

NASA Technical Reports Server (NTRS)

Watson, J. W.; Levine, S. R.

1984-01-01

A study of the effect of plasma spray processing parameters on the life of a two layer thermal barrier coating was conducted. The ceramic layer was plasma sprayed at plasma arc currents of 900 and 600 amps onto uncooled tubes, cooled tubes, and solid bars of Waspalloy in a lathe with 1 or 8 passes of the plasma gun. These processing changes affected the residual stress state of the coating. When the specimens were tested in a Mach 0.3 cyclic burner rig at 1130 deg C, a wide range of coating lives resulted. Processing factors which reduced the residual stress state in the coating, such as reduced plasma temperature and increased heat dissipation, significantly increased coating life.

On the characteristics of centrifugal-reciprocating machines. [cryogenic coolers

NASA Technical Reports Server (NTRS)

Higa, W. H.

1980-01-01

A method of compressing helium gas for cryogenic coolers is presented which uses centrifugal force to reduce the forces on the connecting rod and crankshaft in the usual reciprocating compressor. This is achieved by rotating the piston-cylinder assembly at a speed sufficient for the centrifugal force on the piston to overcome the compressional force due to the working fluid. The rotating assembly is dynamically braked in order to recharge the working space with fluid. The intake stroke consists of decelerating the rotating piston-cylinder assembly and the exhaust stroke consists of accelerating the assembly.

[Stroke in paediatric patients with sickle-cell anaemia].

PubMed

Díaz-Díaz, Judit; Camacho-Salas, Ana; Núñez-Enamorado, Noemí; Carro-Rodríguez, Miguel A; Sánchez-Galán, Victoria; Martínez de Aragón, Ana; Simón-De Las Heras, Rogelio

2014-08-16

Sickle-cell anaemia is the severe homozygotic form of drepanocytosis, a genetic disorder that often occurs among black people and which is characterised by the production of haemoglobin S, chronic hemolytic anaemia and tissue ischaemia due to alterations in blood flow. A quarter of the patients presented neurological manifestations; 8-10% of children will have a stroke. AIM. To analyse the cases of stroke in children with sickle-cell anaemia in our centre. We conducted a retrospective descriptive study of children with sickle-cell anaemia and stroke. Five patients (two Dominicans and three Guineans) with sickle-cell anaemia and stroke; one patient suffered two episodes of stroke. The mean age was 27 months. Five of the episodes were ischaemic infarctions. Stroke was the initial form of presentation of drepanocytosis on three occasions. Two of the strokes occurred within a context of pneumococcal meningitis. Four of the patients had previously reported fever. The initial clinical picture was hemiparesis in four cases. Mean haemoglobin on diagnosing the stroke was 6.5 g/dL. Transcranial ultrasound imaging revealed alterations in three patients and, in all the patients, magnetic resonance imaging revealed lesions, which were bilateral in half the cases. Following the stroke, a hypertransfusion regimen protocol was established and only one patient presented a new stroke. This same patient went on to develop moya-moya disease and was submitted to an indirect revascularisation; the patient progressed well, without presenting any new ischaemic events. Drepanocytosis is a disease that is emerging in our setting as a result of immigration. It should be suspected in cases of paediatric strokes associated to anaemia, above all in black children under the age of five who were not submitted to neonatal screening.

Electron Microscopic Recording of the Power and Recovery Strokes of Individual Myosin Heads Coupled with ATP Hydrolysis: Facts and Implications.

PubMed

Sugi, Haruo; Chaen, Shigeru; Akimoto, Tsuyoshi

2018-05-04

The most straightforward way to get information on the performance of individual myosin heads producing muscle contraction may be to record their movement, coupled with ATP hydrolysis, electron-microscopically using the gas environmental chamber (EC). The EC enables us to visualize and record ATP-induced myosin head movement in hydrated skeletal muscle myosin filaments. When actin filaments are absent, myosin heads fluctuate around a definite neutral position, so that their time-averaged mean position remains unchanged. On application of ATP, myosin heads are found to move away from, but not towards, the bare region, indicating that myosin heads perform a recovery stroke (average amplitude, 6 nm). After exhaustion of ATP, myosin heads return to their neutral position. In the actin⁻myosin filament mixture, myosin heads form rigor actin myosin linkages, and on application of ATP, they perform a power stroke by stretching adjacent elastic structures because of a limited amount of applied ATP ≤ 10 µM. The average amplitude of the power stroke is 3.3 nm and 2.5 nm at the distal and the proximal regions of the myosin head catalytic domain (CAD), respectively. The power stroke amplitude increases appreciably at low ionic strength, which is known to enhance Ca 2+ -activated force in muscle. In both the power and recovery strokes, myosin heads return to their neutral position after exhaustion of ATP.

Two decades of nation-wide community-based stroke support - The Singapore National Stroke Association.

PubMed

Venketasubramanian, Narayanaswamy; Yin, Ann; Lee, Lay B; De Silva, Deidre A

2017-04-01

The Singapore National Stroke Association, registered in 1996, offers support and information to stroke survivors and caregivers, and aims to raise public stroke awareness. In the last 20 years, we have developed programs to equip stroke survivors and caregivers with knowledge, life skills, comfort, and opportunities for socialization and reintegration. We have on-going public education and advocacy initiatives. Obtaining funding, member recruitment, volunteer retention, and leadership renewal are on-going challenges. Singapore National Stroke Association will continue to strive for the betterment of stroke survivors, their caregivers, and the public.

Early seizures predict the development of epilepsy in children and adolescents with stroke.

PubMed

Breitweg, Ina; Stülpnagel, Celina von; Pieper, Tom; Lidzba, Karen; Holthausen, Hans; Staudt, Martin; Kluger, Gerhard

2017-05-01

To identify risk factors for the development of epilepsy after pediatric stroke. Retrospective analysis of hospital charts of 93 children and adolescents with post-neonatal non-traumatic stroke and a minimum follow-up of two years. Seizures during the first 48 h after onset of stroke symptoms were defined as "early seizures"; when two or more seizures occurred after this period, the patient was classified as "epileptic". Early seizures, young age at stroke and MRI evidence of cortical involvement were observed more frequently in the children who developed epilepsy. These factors were, however, significantly interrelated; a stepwise multiple regression analysis in 46/93 patients with complete datasets identified only the occurrence of early seizures as a significant risk factor: 15/19 (79%) children with early seizures developed epilepsy, as opposed to only 7/53 (13%) without early seizures. Children with stroke who show seizures during the first 48 h after onset of stroke symptoms have a high risk to develop post-stroke epilepsy, whereas in children without early seizures, post-stroke epilepsy is rare. Copyright © 2016. Published by Elsevier Ltd.

Telestroke in Northern Alberta: a two year experience with remote hospitals.

PubMed

Khan, Khurshid; Shuaib, Ashfaq; Whittaker, Tammy; Saqqur, Maher; Jeerakathil, Thomas; Butcher, Ken; Crumley, Patrick

2010-11-01

Thrombolysis in acute ischemic stroke is usually performed in comprehensive stroke centres. Lack of stroke expertise in remote small hospitals may preclude thrombolysis. Telemedicine allows such management opportunities in distant hospitals. We report our experience in managing acute stroke over a two-year time period with telestroke. The University of Alberta Hospital acted as the 'hub' and seven remote hospitals as 'spoke'. The neurologist at the 'hub' provided stroke expertise to the local physician using either a two-way video link or telephone. Cranial CT scans were transmitted to 'hub'. Education sessions were held before the initiation of the program. Of 210 patients 44 (21%) received thrombolysis at the 'spoke' sites. In 34/44 (77%) two-way video link was available while in 10/44 (23%) telephone was used. Five (11.4%) patients experienced intracranial hemorrhage after thrombolysis, 2 (4.5%) were symptomatic. Favorable (mRS=0-1) outcome at three months was 16/40 (40%) and mortality was 9/40 (22.5%). Four patients were lost to follow-up. There was no significant three months outcome difference between two-way video link and telephone consultation (P = 0.689). Over two years the number of acute stroke transfers decreased from 144 to 15 at one of the 'spoke' sites, a 92.5% decline. It is possible to successfully treat patients with acute ischemic stroke at remote sites through videoconferencing or telephone consultation. Telestroke can also lead to a significant reduction in the number of patients requiring transfer to a tertiary care centre.

Stand-off CWA imaging system: second sight MS

NASA Astrophysics Data System (ADS)

Bernascolle, Philippe F.; Elichabe, Audrey; Fervel, Franck; Haumonté, Jean-Baptiste

2012-06-01

In recent years, several manufactures of IR imaging devices have launched commercial models applicable to a wide range of chemical species. These cameras are rugged and sufficiently sensitive to detect low concentrations of toxic and combustible gases. Bertin Technologies, specialized in the design and supply of innovating systems for industry, defense and health, has developed a stand-off gas imaging system using a multi-spectral infrared imaging technology. With this system, the gas cloud size, localization and evolution can be displayed in real time. This technology was developed several years ago in partnership with the CEB, a French MoD CBRN organization. The goal was to meet the need for early warning caused by a chemical threat. With a night & day efficiency of up to 5 km, this process is able to detect Chemical Warfare Agents (CWA), critical Toxic Industrial Compounds (TIC) and also flammable gases. The system has been adapted to detect industrial spillage, using off-the-shelf uncooled infrared cameras, allowing 24/7 surveillance without costly frequent maintenance. The changes brought to the system are in compliance with Military Specifications (MS) and primarily focus on the signal processing improving the classification of the detected products and on the simplification of the Human Machine Interface (HMI). Second Sight MS is the only mass produced, passive stand-off CWA imaging system with a wide angle (up to 60°) already used by several regular armies around the world. This paper examines this IR gas imager performance when exposed to several CWA, TIC and simulant compounds. First, we will describe the Second Sight MS system. The theory of gas detection, visualization and classification functions has already been described elsewhere, so we will just summarize it here. We will then present the main topic of this paper which is the results of the tests done in laboratory on live agents and in open field on simulant. The sensitivity threshold of the camera measured in laboratory, on some CWA (G, H agents...) and TIC (ammonia, sulfur dioxide...) will be given. The result of the detection and visualization of a gas cloud in open field testing for some simulants (DMMP, SF6) at a far distance will be also shown.

Differences in stroke and ischemic heart disease mortality by occupation and industry among Japanese working-aged men.

PubMed

Wada, Koji; Eguchi, Hisashi; Prieto-Merino, David

2016-12-01

Occupation- and industry-based risks for stroke and ischemic heart disease may vary among Japanese working-aged men. We examined the differences in mortality rates between stroke and ischemic heart disease by occupation and industry among employed Japanese men aged 25-59 years. In 2010, we obtained occupation- and industry-specific vital statistics data from the Japanese Ministry of Health, Labour, and Welfare dataset. We analyzed data for Japanese men who were aged 25-59 years in 2010, grouped in 5-year age intervals. We estimated the mortality rates of stroke and ischemic heart disease in each age group for occupation and industry categories as defined in the national census. We did not have detailed individual-level variables. We used the number of employees in 2010 as the denominator and the number of events as the numerator, assuming a Poisson distribution. We conducted separate regression models to estimate the incident relative risk for stroke and ischemic heart disease for each category compared with the reference categories "sales" (occupation) and "wholesale and retail" (industry). When compared with the reference groups, we found that occupations and industries with a relatively higher risk of stroke and ischemic heart disease were: service, administrative and managerial, agriculture and fisheries, construction and mining, electricity and gas, transport, and professional and engineering. This suggests there are occupation- and industry-based mortality risk differences of stroke and ischemic heart disease for Japanese working-aged men. These differences in risk might be explained to factors associated with specific occupations or industries, such as lifestyles or work styles, which should be explored in further research. The mortality risk differences of stroke and ischemic heart disease shown in the present study may reflect an excessive risk of Karoshi (death from overwork).

Preburner of Staged Combustion Rocket Engine

NASA Technical Reports Server (NTRS)

Yost, M. C.

1978-01-01

A regeneratively cooled LOX/hydrogen staged combustion assembly system with a 400:1 expansion area ratio nozzle utilizing an 89,000 Newton (20,000 pound) thrust regeneratively cooled thrust chamber and 175:1 tubular nozzle was analyzed, assembled, and tested. The components for this assembly include two spark/torch oxygen-hydrogen igniters, two servo-controlled LOX valves, a preburner injector, a preburner combustor, a main propellant injector, a regeneratively cooled combustion chamber, a regeneratively cooled tubular nozzle with an expansion area ratio of 175:1, an uncooled heavy-wall steel nozzle with an expansion area ratio of 400:1, and interconnecting ducting. The analytical effort was performed to optimize the thermal and structural characteristics of each of the new components and the ducting, and to reverify the capabilities of the previously fabricated components. The testing effort provided a demonstration of the preburner/combustor chamber operation, chamber combustion efficiency and stability, and chamber and nozzle heat transfer.

Evaluation of water cooled supersonic temperature and pressure probes for application to 1366 K flows

NASA Technical Reports Server (NTRS)

Lagen, Nicholas; Seiner, John M.

1990-01-01

Water cooled supersonic probes are developed to investigate total pressure, static pressure, and total temperature in high-temperature jet plumes and thereby determine the mean flow properties. Two probe concepts, designed for operation at up to 1366 K in a Mach 2 flow, are tested on a water cooled nozzle. The two probe designs - the unsymmetric four-tube cooling configuration and the symmetric annular cooling design - take measurements at 755, 1089, and 1366 K of the three parameters. The cooled total and static pressure readings are found to agree with previous test results with uncooled configurations. The total-temperature probe, however, is affected by the introduction of water coolant, and effect which is explained by the increased heat transfer across the thermocouple-bead surface. Further investigation of the effect of coolant on the temperature probe is proposed to mitigate the effect and calculate more accurate temperatures in jet plumes.

A robotic test of proprioception within the hemiparetic arm post-stroke.

PubMed

Simo, Lucia; Botzer, Lior; Ghez, Claude; Scheidt, Robert A

2014-04-30

Proprioception plays important roles in planning and control of limb posture and movement. The impact of proprioceptive deficits on motor function post-stroke has been difficult to elucidate due to limitations in current tests of arm proprioception. Common clinical tests only provide ordinal assessment of proprioceptive integrity (eg. intact, impaired or absent). We introduce a standardized, quantitative method for evaluating proprioception within the arm on a continuous, ratio scale. We demonstrate the approach, which is based on signal detection theory of sensory psychophysics, in two tasks used to characterize motor function after stroke. Hemiparetic stroke survivors and neurologically intact participants attempted to detect displacement- or force-perturbations robotically applied to their arm in a two-interval, two-alternative forced-choice test. A logistic psychometric function parameterized detection of limb perturbations. The shape of this function is determined by two parameters: one corresponds to a signal detection threshold and the other to variability of responses about that threshold. These two parameters define a space in which proprioceptive sensation post-stroke can be compared to that of neurologically-intact people. We used an auditory tone discrimination task to control for potential comprehension, attention and memory deficits. All but one stroke survivor demonstrated competence in performing two-alternative discrimination in the auditory training test. For the remaining stroke survivors, those with clinically identified proprioceptive deficits in the hemiparetic arm or hand had higher detection thresholds and exhibited greater response variability than individuals without proprioceptive deficits. We then identified a normative parameter space determined by the threshold and response variability data collected from neurologically intact participants. By plotting displacement detection performance within this normative space, stroke survivors with and without intact proprioception could be discriminated on a continuous scale that was sensitive to small performance variations, e.g. practice effects across days. The proposed method uses robotic perturbations similar to those used in ongoing studies of motor function post-stroke. The approach is sensitive to small changes in the proprioceptive detection of hand motions. We expect this new robotic assessment will empower future studies to characterize how proprioceptive deficits compromise limb posture and movement control in stroke survivors.

Comparative effectiveness of home blood pressure telemonitoring (HBPTM) plus nurse case management versus HBPTM alone among Black and Hispanic stroke survivors: study protocol for a randomized controlled trial.

PubMed

Spruill, Tanya M; Williams, Olajide; Teresi, Jeanne A; Lehrer, Susan; Pezzin, Liliana; Waddy, Salina P; Lazar, Ronald M; Williams, Stephen K; Jean-Louis, Girardin; Ravenell, Joseph; Penesetti, Sunil; Favate, Albert; Flores, Judith; Henry, Katherine A; Kleiman, Anne; Levine, Steven R; Sinert, Richard; Smith, Teresa Y; Stern, Michelle; Valsamis, Helen; Ogedegbe, Gbenga

2015-03-15

Black and Hispanic stroke survivors experience higher rates of recurrent stroke than whites. This disparity is partly explained by disproportionately higher rates of uncontrolled hypertension in these populations. Home blood pressure telemonitoring (HBPTM) and nurse case management (NCM) have proven efficacy in addressing the multilevel barriers to blood pressure (BP) control and reducing BP. However, the effectiveness of these interventions has not been evaluated in stroke patients. This study is designed to evaluate the comparative effectiveness, cost-effectiveness and sustainability of these two telehealth interventions in reducing BP and recurrent stroke among high-risk Black and Hispanic stroke survivors with uncontrolled hypertension. A total of 450 Black and Hispanic patients with recent nondisabling stroke and uncontrolled hypertension are randomly assigned to one of two 12-month interventions: 1) HBPTM with wireless feedback to primary care providers or 2) HBPTM plus individualized, culturally-tailored, telephone-based NCM. Patients are recruited from stroke centers and primary care practices within the Health and Hospital Corporations (HHC) Network in New York City. Study visits occur at baseline, 6, 12 and 24 months. The primary outcomes are within-patient change in systolic BP at 12 months, and the rate of stroke recurrence at 24 months. The secondary outcome is the comparative cost-effectiveness of the interventions at 12 and 24 months; and exploratory outcomes include changes in stroke risk factors, health behaviors and treatment intensification. Recruitment for the stroke telemonitoring hypertension trial is currently ongoing. The combination of two established and effective interventions along with the utilization of health information technology supports the sustainability of the HBPTM + NCM intervention and feasibility of its widespread implementation. Results of this trial will provide strong empirical evidence to inform clinical guidelines for management of stroke in minority stroke survivors with uncontrolled hypertension. If effective among Black and Hispanic stroke survivors, these interventions have the potential to substantially mitigate racial and ethnic disparities in stroke recurrence. ClinicalTrials.gov NCT02011685 . Registered 10 December 2013.

The thick left ventricular wall of the giraffe heart normalises wall tension, but limits stroke volume and cardiac output.

PubMed

Smerup, Morten; Damkjær, Mads; Brøndum, Emil; Baandrup, Ulrik T; Kristiansen, Steen Buus; Nygaard, Hans; Funder, Jonas; Aalkjær, Christian; Sauer, Cathrine; Buchanan, Rasmus; Bertelsen, Mads Frost; Østergaard, Kristine; Grøndahl, Carsten; Candy, Geoffrey; Hasenkam, J Michael; Secher, Niels H; Bie, Peter; Wang, Tobias

2016-02-01

Giraffes--the tallest extant animals on Earth--are renowned for their high central arterial blood pressure, which is necessary to secure brain perfusion. Arterial pressure may exceed 300 mmHg and has historically been attributed to an exceptionally large heart. Recently, this has been refuted by several studies demonstrating that the mass of giraffe heart is similar to that of other mammals when expressed relative to body mass. It thus remains unexplained how the normal-sized giraffe heart generates such massive arterial pressures. We hypothesized that giraffe hearts have a small intraventricular cavity and a relatively thick ventricular wall, allowing for generation of high arterial pressures at normal left ventricular wall tension. In nine anaesthetized giraffes (495±38 kg), we determined in vivo ventricular dimensions using echocardiography along with intraventricular and aortic pressures to calculate left ventricular wall stress. Cardiac output was also determined by inert gas rebreathing to provide an additional and independent estimate of stroke volume. Echocardiography and inert gas-rebreathing yielded similar cardiac outputs of 16.1±2.5 and 16.4±1.4 l min(-1), respectively. End-diastolic and end-systolic volumes were 521±61 ml and 228±42 ml, respectively, yielding an ejection fraction of 56±4% and a stroke volume of 0.59 ml kg(-1). Left ventricular circumferential wall stress was 7.83±1.76 kPa. We conclude that, relative to body mass, a small left ventricular cavity and a low stroke volume characterizes the giraffe heart. The adaptations result in typical mammalian left ventricular wall tensions, but produce a lowered cardiac output. © 2016. Published by The Company of Biologists Ltd.

Oxide-dispersion-strengthened turbine blades, volume 1

NASA Technical Reports Server (NTRS)

Millan, P. P., Jr.; Mays, J. C.

1986-01-01

The objective of Project 4 was to develop a high-temperature, uncooled gas turbine blade using MA6000 alloy. The program objectives were achieved. Production scale up of the MA6000 alloy was achieved with a fair degree of tolerance to nonoptimum processing. The blade manufacturing process was also optimized. The mechanical, environmental, and physical property evaluations of MA6000 were conducted. The ultimate tensile strength, to about 704 C (130 F), is higher than DS MAR-M 247 but with a corresponding lower tensile elongation. Also, above 982 C (180 F) MA6000 tensile strength does not decrease as rapidly as MAR-M 247 because the ODS mechanism still remains active. Based on oxidation resistance and diffusional stability considerations, NiCrAlY coatings are recommended. CoCrAly coating should be applied on top of a thin NiCrAlY coating. Vibration tests, whirlpit tests, and a high-rotor-rig test were conducted to ensure successful completion of the engine test of the MA6000 TFE731 high pressure turbine blades. The results of these tests were acceptable. In production quantities, the cost of the Project 4 MA6000 blade is estimated to be about twice that of a cast DS MAR-M 247 blade.

G301: The Flying Falcon geological remote sensing experiment

NASA Technical Reports Server (NTRS)

Vincent, Robert K.; Birnbach, Curtis; Mengel, Arthur H.

1995-01-01

Get-Away Special (GAS) G-301, named the Flying Falcon and scheduled for launch on the STS-77 Space Shuttle in April, 1996, is being prepared to perform an experiment designed by the Department of Geology, Bowling Green State University (BGSU). The experiment will employ a new type of infrared imager designed and built by a consortium of Teltron Technologies Inc., Hudson Research Inc., and BGSU that is an uncooled, quantrum ferro-electric, infrared return beam vidicon (IRBV) camera capable of detecting thermal infrared radiation throughout the 2.0-50.0 micron wavelength region, and to which an integral, unable Fabry-Perot filter and a telescopic lens have been added. The primary objectives in the experiment include the mapping of methane plumes from solid waste landfills and wetlands in the midwestern U.S., the mapping of methane plumes offshore in the Gulf of Mexico and in the Middle East, brief monitoring for precursors of volcanoes or earthquakes in the South China sea and the East Pacific Rise (about 300 km west of Easter Island), and the mapping of silica content in exposed outcrops and residual soils of the southwestern U.S. and Middle East.

Oxide-dispersion-strengthened turbine blades. Volume 2

NASA Technical Reports Server (NTRS)

Millan, P. P., Jr.; Mays, J. C.; Humbert, D. R.

1987-01-01

The overall objective of Project 4 was to develop and test a high-temperature, uncooled gas turbine blade using MA6000 alloy. Production scale up of the MA6000 alloy was achieved with a fair degree of tolerance to non-optimum processing. The blade manufacturing process was also optimized. The mechanical, environmental, and physical property evaluations of MA6000 were conducted. The ultimate tensile strength, to about 704 C (1300 F), is higher than DS MAR-M 247 but with a corresponding lower tensile elongation. Also, above 982 C (1800 F) MA6000 tensile strength does not decrease as rapidly as MAR-M 247 because the ODS mechanism still remains active. Based on oxidation resistance and diffusional stability considerations, NiCrAlY coatings are recommended. CoCrAlY coating should be applied on top of a thin NiCrAlY coating if hot corrosion is expected. Vibration, whirlpit, and high-rotor-rig tests were conducted to ensure successful completion of the engine test of the MA6000 TFE731 high pressure turbine blades. Test results were acceptable. In production quantities, the cost of the Project 4 MA6000 blade is estimated to be twice that of a cast DS MAR-M 247 blade.

Burners and combustion apparatus for carbon nanomaterial production

DOEpatents

Alford, J. Michael; Diener, Michael D; Nabity, James; Karpuk, Michael

2013-02-05

The invention provides improved burners, combustion apparatus, and methods for carbon nanomaterial production. The burners of the invention provide sooting flames of fuel and oxidizing gases. The condensable products of combustion produced by the burners of this invention produce carbon nanomaterials including without limitation, soot, fullerenic soot, and fullerenes. The burners of the invention do not require premixing of the fuel and oxidizing gases and are suitable for use with low vapor pressure fuels such as those containing substantial amounts of polyaromatic hydrocarbons. The burners of the invention can operate with a hot (e.g., uncooled) burner surface and require little, if any, cooling or other forms of heat sinking. The burners of the invention comprise one or more refractory elements forming the outlet of the burner at which a flame can be established. The burners of the invention provide for improved flame stability, can be employed with a wider range of fuel/oxidizer (e.g., air) ratios and a wider range of gas velocities, and are generally more efficient than burners using water-cooled metal burner plates. The burners of the invention can also be operated to reduce the formation of undesirable soot deposits on the burner and on surfaces downstream of the burner.

Burners and combustion apparatus for carbon nanomaterial production

DOEpatents

Alford, J. Michael; Diener, Michael D.; Nabity, James; Karpuk, Michael

2007-10-09

The invention provides improved burners, combustion apparatus, and methods for carbon nanomaterial production. The burners of the invention provide sooting flames of fuel and oxidizing gases. The condensable products of combustion produced by the burners of this invention produce carbon nanomaterials including without limitation, soot, fullerenic soot, and fullerenes. The burners of the invention do not require premixing of the fuel and oxidizing gases and are suitable for use with low vapor pressure fuels such as those containing substantial amounts of polyaromatic hydrocarbons. The burners of the invention can operate with a hot (e.g., uncooled) burner surface and require little, if any, cooling or other forms of heat sinking. The burners of the invention comprise one or more refractory elements forming the outlet of the burner at which a flame can be established. The burners of the invention provide for improved flame stability, can be employed with a wider range of fuel/oxidizer (e.g., air) ratios and a wider range of gas velocities, and are generally more efficient than burners using water-cooled metal burner plates. The burners of the invention can also be operated to reduce the formation of undesirable soot deposits on the burner and on surfaces downstream of the burner.

Economic burden of informal care attributable to stroke among those aged 65 years or older in China.

PubMed

Joo, Heesoo; Liang, Di

2017-02-01

Stroke is a leading cause of disability in China, frequently resulting in the need for informal care. No information, however, is available on costs of informal care associated with stroke, required to understand the true cost of stroke in China. Using the 2011 China Health and Retirement Longitudinal Study, we identified 4447 respondents aged ≥65 years suitable for analyses, including 184 stroke survivors. We estimated the economic burden of informal care associated with stroke using a two-part model. The monthly number of hours of informal caregiving associated with stroke was 29.2 h/stroke survivor, and the average annual cost of informal care associated with stroke was 10,612 RMB per stroke survivor. The findings stress the necessity of proper interventions to prevent stroke and will be useful for estimating the economic burden of stroke.

Burden of stroke in Bangladesh.

PubMed

Islam, Md Nazmul; Moniruzzaman, Mohammed; Khalil, Md Ibrahim; Basri, Rehana; Alam, Mohammad Khursheed; Loo, Keat Wei; Gan, Siew Hua

2013-04-01

Stroke is the third leading cause of death in Bangladesh. The World Health Organization ranks Bangladesh's mortality rate due to stroke as number 84 in the world. The reported prevalence of stroke in Bangladesh is 0.3%, although no data on stroke incidence have been recorded. Hospital-based studies conducted in past decades have indicated that hypertension is the main cause of ischaemic and haemorrhagic stroke in Bangladesh. The high number of disability-adjusted life-years lost due to stroke (485 per 10,000 people) show that stroke severely impacts Bangladesh's economy. Although two non-governmental organizations, BRAC and the Centre for the Rehabilitation of the Paralysed, are actively involved in primary stroke prevention strategies, the Bangladeshi government needs to emphasize healthcare development to cope with the increasing population density and to reduce stroke occurrence. © 2012 The Authors. International Journal of Stroke © 2012 World Stroke Organization.

Unmanned Aerial Vehicles Roadmap 2000-2025

DTIC Science & Technology

2001-04-01

Develop and mature enabling materials technologies such as gamma titanium aluminides , refractory intermetallic alloys, ceramic matrix composites, higher...percent (see Figure 4.1.2-1). For UAV use, these goals may partially be met by deleting turbine blade containment rings and redundant controls, as well...and Barium Strontium Titanium (BST) used in uncooled LWIR detectors, and fabrication techniques of thin pixels will enable improved thermal

ManTech Affordability for Defense Weapon Systems

DTIC Science & Technology

2009-11-01

the Virginia Class Submarine Development of Friction Stir Welding for Navy Expeditionary Fighting Vehicle (EFV) Hull Components Procurement...Tile 2007 – Translational Friction Stir Welding 2006 – Engine Rotor Life Extension 2006 – Uncooled Focal Plane Array Producibility 2005 – Large...DDG 1000 with Hybrid Laser Arc Welding The Problem: T-Beam stiffeners, used extensively for decks, bulkheads, and other ship structures, are being

Characterization of Perovskite Films Grown by a Novel Low-Temperature Process for Uncooled IR Detector Applications

DTIC Science & Technology

2008-12-01

hydrolysis and polycondensation of molecular precursors in vitro to form SiO2, anatase-TiO2, and - Ga2O3 under very mild conditions, whereas...forming high temperature crystalline polymorphs of TiO2 and Ga2O3 lies in kinetically controlled, slow catalytic hydrolysis and growth. In an

Spectroscopic Imaging with an Uncooled Microbolometer Infrared Camera and Step-Scan FTIR

DTIC Science & Technology

2006-12-01

NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public released; distribution is unlimited SPECTROSCOPIC...Form Approved OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 hour per response, including the...STATEMENT Approved for public release; distribution is unlimited 12b. DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words) The purpose of this

Enhanced LWIR NUC using an uncooled microbolometer camera

NASA Astrophysics Data System (ADS)

LaVeigne, Joe; Franks, Greg; Sparkman, Kevin; Prewarski, Marcus; Nehring, Brian

2011-06-01

Performing a good non-uniformity correction is a key part of achieving optimal performance from an infrared scene projector, and the best NUC is performed in the band of interest for the sensor being tested. While cooled, large format MWIR cameras are readily available and have been successfully used to perform NUC, similar cooled, large format LWIR cameras are not as common and are prohibitively expensive. Large format uncooled cameras are far more available and affordable, but present a range of challenges in practical use for performing NUC on an IRSP. Some of these challenges were discussed in a previous paper. In this discussion, we report results from a continuing development program to use a microbolometer camera to perform LWIR NUC on an IRSP. Camera instability and temporal response and thermal resolution were the main problems, and have been solved by the implementation of several compensation strategies as well as hardware used to stabilize the camera. In addition, other processes have been developed to allow iterative improvement as well as supporting changes of the post-NUC lookup table without requiring re-collection of the pre-NUC data with the new LUT in use.

The development of a μ-biomimetic uncooled IR-Sensor inspired by the infrared receptors of Melanophila acuminata.

PubMed

Siebke, Georg; Holik, Peter; Schmitz, Sam; Tätzner, Simon; Thiesler, Jan; Steltenkamp, Siegfried

2015-03-30

The beetle Melanophila acuminata uses a specialized organ to detect infrared radiation. The organ consists of about 100 individual sensilla. The main component of the sensillum is a pressure chamber. Upon absorption of radiation, the pressure increases, and the tip of a dendrite is deformed. A unique feature of the organ is a compensation mechanism that prevents large pressures. The beetle uses this organ to detect forest fires and to navigate inside burning woods. However, the sensitivity is part of a long-lasting discussion, providing thresholds between [Formula: see text] and [Formula: see text]. To end the decade-long discussion and to provide a novel type of infrared sensor, we are developing an uncooled μ-biomimetic infrared (IR) sensor inspired by Melanophila acuminata using MEMS technology. Here, we present the development of a μ-capacitor that is used to detect pressure changes and the characterization of the compensation mechanism. We describe the microtechnological fabrication process for air-filled capacitors with a ratio of diameter-to-electrode distance of 1000 and a technique to fill the sensor bubble-free with water. Finally, we estimate the sensitivity of the beetle using a theoretical model of the sensillum.

320 x 240 uncooled IRFPA with pixel wise thin film vacuum packaging

NASA Astrophysics Data System (ADS)

Yon, J.-J.; Dumont, G.; Rabaud, W.; Becker, S.; Carle, L.; Goudon, V.; Vialle, C.; Hamelin, A.; Arnaud, A.

2012-10-01

Silicon based vacuum packaging is a key enabling technology for achieving affordable uncooled Infrared Focal Plane Arrays (IRFPA) as required by the promising mass market for very low cost IR applications, such as automotive driving assistance, energy loss monitoring in buildings, motion sensors… Among the various approaches studied worldwide, the CEA, LETI is developing a unique technology where each bolometer pixel is sealed under vacuum at the wafer level, using an IR transparent thin film deposition. This technology referred to as PLP (Pixel Level Packaging), leads to an array of hermetic micro-caps each containing a single microbolometer. Since the successful demonstration that the PLP technology, when applied on a single microbolometer pixel, can provide the required vacuum < 10-3 mbar, the authors have pushed forward the development of the technology on fully operational QVGA readout circuits CMOS base wafers (320 x 240 pixels). In this outlook, the article reports on the electro optical performance obtained from this preliminary PLP based QVGA demonstrator. Apart from the response, noise and NETD distributions, the paper also puts emphasis on additional key features such as thermal time constant, image quality, and ageing properties.

Long wave infrared (8 to 14 microns) hyperspectral imager based on an uncooled thermal camera and the traditional CI block interferometer (SI-LWIR-UC)

NASA Astrophysics Data System (ADS)

Cabib, Dario; Lavi, Moshe; Gil, Amir; Milman, Uri

2011-06-01

Since the early '90's CI has been involved in the development of FTIR hyperspectral imagers based on a Sagnac or similar type of interferometer. CI also pioneered the commercialization of such hyperspectral imagers in those years. After having developed a visible version based on a CCD in the early '90's (taken on by a spin-off company for biomedical applications) and a 3 to 5 micron infrared version based on a cooled InSb camera in 2008, it is now developing an LWIR version based on an uncooled camera for the 8 to 14 microns range. In this paper we will present design features and expected performance of the system. The instrument is designed to be rugged for field use, yield a relatively high spectral resolution of 8 cm-1, an IFOV of 0.5 mrad., a 640x480 pixel spectral cube in less than a minute and a noise equivalent spectral radiance of 40 nW/cm2/sr/cm-1 at 10μ. The actually measured performance will be presented in a future paper.

Metal silicide/poly-Si Schottky diodes for uncooled microbolometers.

PubMed

Chizh, Kirill V; Chapnin, Valery A; Kalinushkin, Victor P; Resnik, Vladimir Y; Storozhevykh, Mikhail S; Yuryev, Vladimir A

2013-04-17

: Nickel silicide Schottky diodes formed on polycrystalline Si 〈P〉 films are proposed as temperature sensors of monolithic uncooled microbolometer infrared focal plane arrays. The structure and composition of nickel silicide/polycrystalline silicon films synthesized in a low-temperature process are examined by means of transmission electron microscopy. The Ni silicide is identified as a multi-phase compound composed of 20% to 40% of Ni3Si, 30% to 60% of Ni2Si, and 10% to 30% of NiSi with probable minor content of NiSi2 at the silicide/poly-Si interface. Rectification ratios of the Schottky diodes vary from about 100 to about 20 for the temperature increasing from 22â"ƒ to 70â"ƒ; they exceed 1,000 at 80 K. A barrier of around 0.95 eV is found to control the photovoltage spectra at room temperature. A set of barriers is observed in photo-electromotive force spectra at 80 K and attributed to the Ni silicide/poly-Si interface. Absolute values of temperature coefficients of voltage and current are found to vary from 0.3%â"ƒ to 0.6%/â"ƒ for forward bias and around 2.5%/â"ƒ for reverse bias of the diodes.

Stroke survivors in Nigeria: A door-to-door prevalence survey from the Niger Delta region.

PubMed

Ezejimofor, Martinsixtus C; Uthman, Olalekan A; Maduka, Omosivie; Ezeabasili, Aloysius C; Onwuchekwa, Arthur C; Ezejimofor, Benedeth C; Asuquo, Eme; Chen, Yen-Fu; Stranges, Saverio; Kandala, Ngianga-Bakwin

2017-01-15

The burden of stroke has been projected to increase in low-and middle-income countries due to the ongoing epidemiological transition. However, community-based stroke prevalence studies are sparse in sub-Saharan Africa particularly in Nigeria. This study aimed to provide a comparative estimate of the prevalence of stroke survivors in the rural Niger Delta region. A three-phased door-to-door survey was conducted using WHO modified instruments. In the first-phase, 2028 adults (≥18years) participants randomly selected from two rural communities were screened by trained health research assistants for probable stroke. In the second phase, suspected cases were screened with stroke-specific tool. Positive cases were made to undergo complete neurological evaluation by two study neurologist in phase-three. Stroke diagnosis was based on clinical evaluation using WHO criteria. Overall, 27 (8 first-ever and 19 recurrent cases) stroke survivors with crude prevalence of 13.31/1000 (95% CI, 8.32-18.31) and a non-significant difference in prevalence between the two study communities were found, (P=0.393I). In addition, age-adjusted prevalence of stroke survivors was 14.6/1000 person, about 7-folds higher than previous estimates outside the Niger Delta region. The prevalence increases significantly with advancing in age, P<0·001. Among others, hypertension (92.59%) was the commonest risk factor and comorbidity found. Improved stroke surveillance and care, as well as better management of the underlying risk factors, primarily undetected or uncontrolled high blood pressure, remains a public health priority. Copyright © 2016 Elsevier B.V. All rights reserved.

Stroke

MedlinePlus

... emergency. Strokes happen when blood flow to your brain stops. Within minutes, brain cells begin to die. There are two kinds ... blocks or plugs a blood vessel in the brain. The other kind, called hemorrhagic stroke, is caused ...

Post-epilepsy stroke: A review.

PubMed

Jin, Jing; Chen, Rong; Xiao, Zheng

2016-01-01

Stroke and epilepsy are two of the most common neurological disorders and share a complicated relationship. It is well established that stroke is one of the most important causes of epilepsy, particularly new-onset epilepsy among the elderly. However, post-epilepsy stroke has been overlooked. In recent years, it has been demonstrated that epilepsy patients have increased risk and mortality from stroke when compared with the general population. Additionally, it was proposed that post-epilepsy stroke might be associated with antiepileptic drugs (AEDs), epileptic seizures and the lifestyle of epileptic patients. Here, we comprehensively review the epidemiology, causes and interventions for post-epilepsy stroke.

Therapeutic role of music listening in stroke rehabilitation.

PubMed

Forsblom, Anita; Laitinen, Sari; Särkämö, Teppo; Tervaniemi, Mari

2009-07-01

We performed two parallel interview studies of stroke patients (n= 20) and professional nurses (n= 5) to gain more insight into the therapeutic role of music listening in stroke rehabilitation. Results suggest that music listening can be used to relax, improve mood, and provide both physical and mental activation during the early stages of recovery from stroke. Thus, music listening could provide a useful clinical tool in stroke rehabilitation.

Vinpocetine for acute ischaemic stroke.

PubMed

Bereczki, D; Fekete, I

2008-01-23

Vasoactive and neuroprotective drugs such as vinpocetine are used to treat stroke in some countries. To assess the effect of vinpocetine in acute ischaemic stroke. We searched the Cochrane Stroke Group Trials Register (last searched February 2007), MEDLINE (1966 to February 2007) and Scopus (1960 to February 2007). We also searched the Internet Stroke Center Stroke Trials Registry, Google Scholar, the science-specific search engine Scirus and Wanfang Data, the leading information provider in China. We contacted researchers in the field and four pharmaceutical companies that manufacture vinpocetine. Searches were complete to February 2007. Unconfounded randomised trials of vinpocetine compared with placebo, or any other reference treatment, in people with acute ischaemic stroke. We included trials if treatment started no later than 14 days after stroke onset. Two review authors independently applied the inclusion criteria. One review author extracted the data, which was then checked by the second review author. We assessed trial quality. The primary outcome measure was death or dependency. We included two trials, involving a total of 70 participants. Data for 63 participants were reported in the two trials combined. The rate of death or dependency did not differ between the treatment and placebo groups at one and three months. The 95% confidence intervals for the outcome measures were wide and included the possibility of both significant benefit and significant harm. No adverse effects were reported. There is not enough evidence to evaluate the effect of vinpocetine on survival or dependency in patients with acute ischaemic stroke.

The Big Five personality factors and psychological well-being following stroke: a systematic review.

PubMed

Dwan, Toni; Ownsworth, Tamara

2017-12-22

To identify and appraise studies investigating the relationship between the Big Five personality factors and psychological well-being following stroke and evidence for personality change. Systematic searches of six databases (PsychINFO, CINAHL, Ovid Medline, Cochrane, PubMed, and Web of Science) were conducted from inception to June 2017. Studies involving adult stroke samples that employed a validated measure of at least one of the Big Five personality factors were included. Two reviewers independently assessed the eligibility and methodological quality of studies. Eleven studies were identified that assessed associations between personality and psychological well-being after stroke (nine studies) or post-stroke personality change (two studies). A consistent finding was that higher neuroticism was significantly related to poorer psychological well-being. The evidence for the other Big Five factors was mixed. In terms of personality change, two cross-sectional studies reported high rates of elevated neuroticism (38-48%) and low extraversion (33-40%) relative to normative data. Different questionnaires and approaches to measuring personality (i.e., self vs. informant ratings, premorbid personality vs. current personality) complicated comparisons between studies. People high on neuroticism are at increased risk of poor psychological well-being after stroke. Prospective longitudinal studies are needed to address the limited research on post-stroke personality change. Implications for rehabilitation High neuroticism is associated with poorer psychological well-being after stroke. Assessing personality characteristics early after stroke may help to identify those at risk of poor psychological outcomes.

A conceptual study of the potential for automotive-derived and free-piston Stirling engines in 30- to 400-kilowatt stationary power applications

NASA Technical Reports Server (NTRS)

Vatsky, A.; Chen, H. S.; Dineen, J.

1982-01-01

The technical feasibility of applying automotive-derived kinematic and free-piston Stirling engine concepts for stationary applications was explored. Automotive-derived engines offer cost advantages by providing a mature and developd engine technology base with downrating and parts commonality options for specific applications. Two engine sizes (30 and 400 kW), two Stirling engine configurations (kinematic and free-piston), and two output systems (crankshaft and hydraulic pump) were studied. The study includes the influences of using either hydrogen or helium as the working gas. The first kinematic configuration selects an existing Stirling engine design from an automotive application and adapts it to stationary requirements. A 50,000-hour life requirement was established by downrating the engine to 40 kW and reducing auxiliary loads. Efficiency improvements were gained by selective material and geometric variations and peak brake efficiency of 36.8 percent using helium gas was achieved. The second design was a four-cylinder, 400 kW engine, utilizing a new output drive system known as the z-crank, which provides lower friction losses and variable stroke power control. Three different material and working gas combinations were considered. Brake efficiency levels varied from 40.5 percent to 45.6 percent. A 37.5 kW single-cycle, free-piston hydraulic output design was generated by scaling one cylinder of the original automotive engine and mating it to a counterbalanced reciprocal hydraulic pump. Metallic diaphragms were utilized to transmit power.

A conceptual study of the potential for automotive-derived and free-piston Stirling engines in 30- to 400-kilowatt stationary power applications

NASA Astrophysics Data System (ADS)

Vatsky, A.; Chen, H. S.; Dineen, J.

1982-05-01

The technical feasibility of applying automotive-derived kinematic and free-piston Stirling engine concepts for stationary applications was explored. Automotive-derived engines offer cost advantages by providing a mature and developd engine technology base with downrating and parts commonality options for specific applications. Two engine sizes (30 and 400 kW), two Stirling engine configurations (kinematic and free-piston), and two output systems (crankshaft and hydraulic pump) were studied. The study includes the influences of using either hydrogen or helium as the working gas. The first kinematic configuration selects an existing Stirling engine design from an automotive application and adapts it to stationary requirements. A 50,000-hour life requirement was established by downrating the engine to 40 kW and reducing auxiliary loads. Efficiency improvements were gained by selective material and geometric variations and peak brake efficiency of 36.8 percent using helium gas was achieved. The second design was a four-cylinder, 400 kW engine, utilizing a new output drive system known as the z-crank, which provides lower friction losses and variable stroke power control. Three different material and working gas combinations were considered. Brake efficiency levels varied from 40.5 percent to 45.6 percent. A 37.5 kW single-cycle, free-piston hydraulic output design was generated by scaling one cylinder of the original automotive engine and mating it to a counterbalanced reciprocal hydraulic pump. Metallic diaphragms were utilized to transmit power.

Retrospective audit of the acute management of stroke in two district general hospitals in the uk.

PubMed

Faluyi, O O; Omodara, J A; Tay, K H; Muhiddin, K

2008-06-01

There is some evidence to suggest that the standard of acute medical care provided to patients with cerebrovascular disease is a major determinant of the eventual outcome. Consequently, the Royal College of Physicians (RCP) of London issues periodic guidelines to assist healthcare providers in the management of patients presenting with stroke. An audit of the acute management of stroke in two hospitals belonging to the same health care trust in the UK. Retrospective review of 98 randomly selected case-notes of patients managed for cerebrovascular disease in two acute hospitals in the UK between April and June 2004. The pertinent guidelines of RCP (London) are highlighted while audit targets were set at 70%. 84% of patients presenting with cerebrovascular disease had a stroke rather than a TIA, anterior circulation strokes were commonest. All patients with stroke were admitted while those with TIAs were discharged on the same day but most patients with TIA were not followed up by Stroke specialists. Most CT-imaging of the head was done after 24 hours delaying the commencement of anti-platelets for patients with ischaemic stroke or neurosurgical referral for haemorrhagic stroke. Furthermore, there was a low rate of referral for carotid ultrasound in patients with anterior circulation strokes. Anti-platelets and statins were commenced for most patients with ischaemic stroke while diabetes was well controlled in most of them. However, ACE-inhibitors and diuretics such as indapamide were under-utilized for secondary prevention in such patients. Warfarin anti-coagulation was underutilized in patients with ischaemic stroke who had underlying chronic atrial fibrillation. While there was significant multi-disciplinary team input, dysphagia and physiotherapy assessments were delayed. Similarly, occupational therapy input and psychological assesment were omitted from the care of most patients. Hospital service provision for the management of cerebrovascular disease needs to provide appropriate specialist follow up for patients with TIA, prompt radiological imaging and multi-disciplinary team input for patients with stroke. Furthermore, physicians need to utilize appropriate antihypertensives and anti-coagulation more frequently in the secondary prevention of stroke.

RETROSPECTIVE AUDIT OF THE ACUTE MANAGEMENT OF STROKE IN TWO DISTRICT GENERAL HOSPITALS IN THE UK.

PubMed Central

Faluyi, O.O.; Omodara, J.A.; Tay, K.H.; Muhiddin, K.

2008-01-01

Background: There is some evidence to suggest that the standard of acute medical care provided to patients with cerebrovascular disease is a major determinant of the eventual outcome. Consequently, the Royal College of Physicians (RCP) of London issues periodic guidelines to assist healthcare providers in the management of patients presenting with stroke. Objective: An audit of the acute management of stroke in two hospitals belonging to the same health care trust in the UK. Method: Retrospective review of 98 randomly selected case-notes of patients managed for cerebrovascular disease in two acute hospitals in the UK between April and June 2004. The pertinent guidelines of RCP (London) are highlighted while audit targets were set at 70%. Results: 84% of patients presenting with cerebrovascular disease had a stroke rather than a TIA, anterior circulation strokes were commonest. All patients with stroke were admitted while those with TIAs were discharged on the same day but most patients with TIA were not followed up by Stroke specialists. Most CT-imaging of the head was done after 24 hours delaying the commencement of anti-platelets for patients with ischaemic stroke or neurosurgical referral for haemorrhagic stroke. Furthermore, there was a low rate of referral for carotid ultrasound in patients with anterior circulation strokes. Anti-platelets and statins were commenced for most patients with ischaemic stroke while diabetes was well controlled in most of them. However, ACE-inhibitors and diuretics such as indapamide were under-utilized for secondary prevention in such patients. Warfarin anti-coagulation was underutilized in patients with ischaemic stroke who had underlying chronic atrial fibrillation. While there was significant multi-disciplinary team input, dysphagia and physiotherapy assessments were delayed. Similarly, occupational therapy input and psychological assesment were omitted from the care of most patients. Conclusion: Hospital service provision for the management of cerebrovascular disease needs to provide appropriate specialist follow up for patients with TIA, prompt radiological imaging and multi-disciplinary team input for patients with stroke. Furthermore, physicians need to utilize appropriate antihypertensives and anti-coagulation more frequently in the secondary prevention of stroke. PMID:25161444

Changes in Depressive Symptoms and Subsequent Risk of Stroke in the Cardiovascular Health Study

PubMed Central

Gilsanz, Paola; Kubzansky, Laura D.; Tchetgen Tchetgen, Eric J.; Wang, Qianyi; Kawachi, Ichiro; Patton, Kristen K.; Fitzpatrick, Annette L.; Kop, Willem J.; Longstreth, W.T.; Glymour, M. Maria

2016-01-01

Background and Purpose Depression is associated with stroke, but the effects of changes in depressive symptoms on stroke risk are not well understood. This study examined whether depressive symptom changes across two successive annual assessments were associated with incident stroke the following year. Methods We used visit data from 4,319 participants of the Cardiovascular Health Study who were stroke-free at baseline to examine whether changes in depressive symptoms classified across two consecutive annual assessments predicted incident first stroke during the subsequent year. Depressive symptoms were assessed using the 10-item Center for Epidemiologic Studies Depression scale (CES-D; high vs. low at ≥10). Survival models were inverse probability weighted to adjust for demographics, health behaviors, medical conditions, past depressive symptoms, censoring, and survival. Results During follow-up, 334 strokes occurred. Relative to stable low scores of depressive symptoms, improved depression symptoms were associated with almost no excess risk of stroke (aHR=1.02; 95% CI: 0.66–1.58). New-onset symptoms were non-significantly associated with elevated stroke risk (aHR=1.44; 95% CI: 0.97–2.14) while persistently high depressive symptoms were associated with elevated adjusted hazard of all-cause stroke (aHR=1.65; 95% CI: 1.06–2.56). No evidence for effect modification by race, age, or sex was found. Conclusions Persistently high symptoms of depression predicted elevated hazard of stroke. Participants with improved depressive symptoms had no elevation in stroke risk. Such findings suggest that strategies to reduce depressive symptoms may ameliorate stroke risk. PMID:27924053

The effect of spectral filters on visual search in stroke patients.

PubMed

Beasley, Ian G; Davies, Leon N

2013-01-01

Visual search impairment can occur following stroke. The utility of optimal spectral filters on visual search in stroke patients has not been considered to date. The present study measured the effect of optimal spectral filters on visual search response time and accuracy, using a task requiring serial processing. A stroke and control cohort undertook the task three times: (i) using an optimally selected spectral filter; (ii) the subjects were randomly assigned to two groups with group 1 using an optimal filter for two weeks, whereas group 2 used a grey filter for two weeks; (iii) the groups were crossed over with group 1 using a grey filter for a further two weeks and group 2 given an optimal filter, before undertaking the task for the final time. Initial use of an optimal spectral filter improved visual search response time but not error scores in the stroke cohort. Prolonged use of neither an optimal nor a grey filter improved response time or reduced error scores. In fact, response times increased with the filter, regardless of its type, for stroke and control subjects; this outcome may be due to contrast reduction or a reflection of task design, given that significant practice effects were noted.

Uncooled infrared photon detection concepts and devices

NASA Astrophysics Data System (ADS)

Piyankarage, Viraj Vishwakantha Jayaweera

This work describes infrared (IR) photon detector techniques based on novel semiconductor device concepts and detector designs. The aim of the investigation was to examine alternative IR detection concepts with a view to resolve some of the issues of existing IR detectors such as operating temperature and response range. Systems were fabricated to demonstrate the following IR detection concepts and determine detector parameters: (i) Near-infrared (NIR) detection based on dye-sensitization of nanostructured semiconductors, (ii) Displacement currents in semiconductor quantum dots (QDs) embedded dielectric media, (iii) Split-off band transitions in GaAs/AlGaAs heterojunction interfacial workfunction internal photoemission (HEIWIP) detectors. A far-infrared detector based on GaSb homojunction interfacial workfunction internal photoemission (HIWIP) structure is also discussed. Device concepts, detector structures, and experimental results discussed in the text are summarized below. Dye-sensitized (DS) detector structures consisting of n-TiO 2/Dye/p-CuSCN heterostructures with several IR-sensitive dyes showed response peaks at 808, 812, 858, 866, 876, and 1056 nm at room temperature. The peak specific-detectivity (D*) was 9.5x1010 cm Hz-1/2 W-1 at 812 nm at room temperature. Radiation induced carrier generation alters the electronic polarizability of QDs provided the quenching of excitation is suppressed by separation of the QDs. A device constructed to illustrate this concept by embedding PbS QDs in paraffin wax showed a peak D* of 3x108 cm Hz 1/2 W-1 at ˜540 nm at ambient temperature. A typical HEIWIP/HIWIP detector structures consist of single (or multiple) period(s) of doped emitter(s) and undoped barrier(s) which are sandwiched between two highly doped contact layers. A p-GaAs/AlGaAs HEIWIP structure showed enhanced absorption in NIR range due to heavy/light-hole band to split-off band transitions and leading to the development of GaAs based uncooled sensors for IR detection in the 2--5 microm wavelength range with a peak D* of 6.8x105 cm Hz1/2 W-1. A HIWIP detector based on p-GaSb/GaSb showed a free carrier response threshold wavelength at 97 microm (˜3 THz) with a peak D* of 5.7x1011 cm Hz1/2 W-1 at 36 microm and 4.9 K. In this detector, a bolometric type response in the 97--200 microm (3--1.5 THz) range was also observed. INDEX WORDS: Infrared detectors, Photon detection, NIR detectors, THz detectors, Uncooled detectors, Dye-sensitized, IR dye, Quantum dot, Split-off band, GaSb, GaAs, AlGaAs, TiO2, CuSCN, PbS, Homojunction, Heterojunction, Workfunction, Photoemission, Displacement currents, 1/f noise.

Stroke subtyping for genetic association studies? A comparison of the CCS and TOAST classifications.

PubMed

Lanfranconi, Silvia; Markus, Hugh S

2013-12-01

A reliable and reproducible classification system of stroke subtype is essential for epidemiological and genetic studies. The Causative Classification of Stroke system is an evidence-based computerized algorithm with excellent inter-rater reliability. It has been suggested that, compared to the Trial of ORG 10172 in Acute Stroke Treatment classification, it increases the proportion of cases with defined subtype that may increase power in genetic association studies. We compared Trial of ORG 10172 in Acute Stroke Treatment and Causative Classification of Stroke system classifications in a large cohort of well-phenotyped stroke patients. Six hundred ninety consecutively recruited patients with first-ever ischemic stroke were classified, using review of clinical data and original imaging, according to the Trial of ORG 10172 in Acute Stroke Treatment and Causative Classification of Stroke system classifications. There was excellent agreement subtype assigned by between Trial of ORG 10172 in Acute Stroke Treatment and Causative Classification of Stroke system (kappa = 0·85). The agreement was excellent for the major individual subtypes: large artery atherosclerosis kappa = 0·888, small-artery occlusion kappa = 0·869, cardiac embolism kappa = 0·89, and undetermined category kappa = 0·884. There was only moderate agreement (kappa = 0·41) for the subjects with at least two competing underlying mechanism. Thirty-five (5·8%) patients classified as undetermined by Trial of ORG 10172 in Acute Stroke Treatment were assigned to a definite subtype by Causative Classification of Stroke system. Thirty-two subjects assigned to a definite subtype by Trial of ORG 10172 in Acute Stroke Treatment were classified as undetermined by Causative Classification of Stroke system. There is excellent agreement between classification using Trial of ORG 10172 in Acute Stroke Treatment and Causative Classification of Stroke systems but no evidence that Causative Classification of Stroke system reduced the proportion of patients classified to undetermined subtypes. The excellent inter-rater reproducibility and web-based semiautomated nature make Causative Classification of Stroke system suitable for multicenter studies, but the benefit of reclassifying cases already classified using the Trial of ORG 10172 in Acute Stroke Treatment system on existing databases is likely to be small. © 2012 The Authors. International Journal of Stroke © 2012 World Stroke Organization.

Stroke awareness among inpatient nursing staff at an academic medical center

PubMed Central

Adelman, Eric E.; Meurer, William J.; Nance, Dorinda K.; Kocan, Mary Jo; Maddox, Kate E.; Morgenstern, Lewis B.; Skolarus, Lesli E.

2015-01-01

Background and Purpose Since 10% of strokes occur in hospitalized patients, we sought to evaluate stroke knowledge and predictors of stroke knowledge among inpatient and emergency department nursing staff. Methods Nursing staff completed an on-line stroke survey. The survey queried outcome expectations (the importance of rapid stroke identification), self-efficacy in recognizing stroke, and stroke knowledge (name three stroke warning signs/symptoms). Adequate stroke knowledge was defined as the ability to name two or more stroke warning signs. Logistic regression was used to identify the association between stroke symptom knowledge and staff characteristics (education, clinical experience, and nursing unit), stroke self-efficacy, and outcome expectations. Results A total of 875 respondents (84% response rate) completed the survey and most of the respondents were nurses. More than 85% of respondents correctly reported 2 or more stroke warning signs or symptoms. Greater self-efficacy in identifying stroke symptoms (OR 1.13, 95% CI 1.01–1.27) and higher ratings for the importance of rapid identification of stroke symptoms (OR 1.23, 95% CI 1.002–1.51) were associated with stroke knowledge. Clinical experience, educational experience, nursing unit, and personal knowledge of a stroke patient were not associated with stroke knowledge. Conclusions Stroke outcome expectations and self-efficacy are associated with stroke knowledge and should be included in nursing education about stroke. PMID:24135928

Analysis of spontaneous oscillations for a three-state power-stroke model.

PubMed

Washio, Takumi; Hisada, Toshiaki; Shintani, Seine A; Higuchi, Hideo

2017-02-01

Our study considers the mechanism of the spontaneous oscillations of molecular motors that are driven by the power stroke principle by applying linear stability analysis around the stationary solution. By representing the coupling equation of microscopic molecular motor dynamics and mesoscopic sarcomeric dynamics by a rank-1 updated matrix system, we derived the analytical representations of the eigenmodes of the Jacobian matrix that cause the oscillation. Based on these analytical representations, we successfully derived the essential conditions for the oscillation in terms of the rate constants of the power stroke and the reversal stroke transitions of the molecular motor. Unlike the two-state model, in which the dependence of the detachment rates on the motor coordinates or the applied forces on the motors plays a key role for the oscillation, our three-state power stroke model demonstrates that the dependence of the rate constants of the power and reversal strokes on the strains in the elastic elements in the motor molecules plays a key role, where these rate constants are rationally determined from the free energy available for the power stroke, the stiffness of the elastic element in the molecular motor, and the working stroke size. By applying the experimentally confirmed values to the free energy, the stiffness, and the working stroke size, our numerical model reproduces well the experimentally observed oscillatory behavior. Furthermore, our analysis shows that two eigenmodes with real positive eigenvalues characterize the oscillatory behavior, where the eigenmode with the larger eigenvalue indicates the transient of the system of the quick sarcomeric lengthening induced by the collective reversal strokes, and the smaller eigenvalue correlates with the speed of sarcomeric shortening, which is much slower than lengthening. Applying the perturbation analyses with primal physical parameters, we find that these two real eigenvalues occur on two branches derived from a merge point of a pair of complex-conjugate eigenvalues generated by Hopf bifurcation.

Climate and health relevant emissions from in-use Indian three-wheelers fueled by natural gas and gasoline.

PubMed

Reynolds, Conor C O; Grieshop, Andrew P; Kandlikar, Milind

2011-03-15

Auto-rickshaws in India use different fuels and engine technologies, with varying emissions and implications for air quality and climate change. Chassis dynamometer emission testing was conducted on 30 in-use auto-rickshaws to quantify the impact of switching from gasoline to compressed natural gas (CNG) in spark-ignition engines. Thirteen test vehicles had two-stroke CNG engines (CNG-2S) and 17 had four-stroke CNG engines (CNG-4S), of which 11 were dual-fuel and operable on a back-up gasoline (petrol) system (PET-4S). Fuel-based emission factors were determined for gaseous pollutants (CO(2), CH(4), NO(X), THC, and CO) and fine particulate matter (PM(2.5)). Intervehicle variability was high, and for most pollutants there was no significant difference (95% confidence level) between "old" (1998-2001) and "new" (2007-2009) age-groups within a given fuel-technology class. Mean fuel-based PM(2.5) emission factor (mean (95% confidence interval)) for CNG-2S (14.2 g kg(-1) (6.2-26.7)) was almost 30 times higher than for CNG-4S (0.5 g kg(-1) (0.3-0.9)) and 12 times higher than for PET-4S (1.2 g kg(-1) (0.8-1.7)). Global warming commitment associated with emissions from CNG-2S was more than twice that from CNG-4S or PET-4S, due mostly to CH(4) emissions. Comprehensive measurements and data should drive policy interventions rather than assumptions about the impacts of clean fuels.

Validity of the growth model of the 'computerized visual perception assessment tool for Chinese characters structures'.

PubMed

Wu, Huey-Min; Li, Cheng-Hsaun; Kuo, Bor-Chen; Yang, Yu-Mao; Lin, Chin-Kai; Wan, Wei-Hsiang

2017-08-01

Morphological awareness is the foundation for the important developmental skills involved with vocabulary, as well as understanding the meaning of words, orthographic knowledge, reading, and writing. Visual perception of space and radicals in two-dimensional positions of Chinese characters' morphology is very important in identifying Chinese characters. The important predictive variables of special and visual perception in Chinese characters identification were investigated in the growth model in this research. The assessment tool is the "Computerized Visual Perception Assessment Tool for Chinese Characters Structures" developed by this study. There are two constructs, basic stroke and character structure. In the basic stroke, there are three subtests of one, two, and more than three strokes. In the character structure, there are three subtests of single-component character, horizontal-compound character, and vertical-compound character. This study used purposive sampling. In the first year, 551 children 4-6 years old participated in the study and were monitored for one year. In the second year, 388 children remained in the study and the successful follow-up rate was 70.4%. This study used a two-wave cross-lagged panel design to validate the growth model of the basic stroke and the character structure. There was significant correlation of the basic stroke and the character structure at different time points. The abilities in the basic stroke and in the character structure steadily developed over time for preschool children. Children's knowledge of the basic stroke effectively predicted their knowledge of the basic stroke and the character structure. Copyright © 2017 Elsevier Ltd. All rights reserved.

Technology for low-cost PIR security sensors

NASA Astrophysics Data System (ADS)

Liddiard, Kevin C.

2008-03-01

Current passive infrared (PIR) security sensors employing pyroelectric detectors are simple, cheap and reliable, but have several deficiencies. These sensors, developed two decades ago, are essentially short-range moving-target hotspot detectors. They cannot detect slow temperature changes, and thus are unable to respond to radiation stimuli indicating potential danger such as overheating electrical appliances and developing fires. They have a poor optical resolution and limited ability to recognize detected targets. Modern uncooled thermal infrared technology has vastly superior performance but as yet is too costly to challenge the PIR security sensor market. In this paper microbolometer technology will be discussed which can provide enhanced performance at acceptable cost. In addition to security sensing the technology has numerous applications in the military, industrial and domestic markets where target range is short and low cost is paramount.

Athletics, minor trauma, and pediatric arterial ischemic stroke.

PubMed

Sepelyak, Kathryn; Gailloud, Philippe; Jordan, Lori C

2010-05-01

Pediatric arterial ischemic stroke may occur as the result of trivial head or neck trauma sustained during a sports activity. We describe three cases of sports-related stroke in previously healthy school-age children and discuss acute and long-term stroke care. Possible mechanisms of sports-related stroke are addressed, as is evaluation for cause of stroke in children. In one of the reported cases, the child was found to have a vertebral artery dissection as the cause of his stroke, but no definitive cause of stroke was identified in the other two cases despite extensive evaluation. The advisability and timing of returning to athletic activities after stroke is also discussed. Many children with sports-related stroke are initially seen by a sports trainer, a pediatrician, or an ER physician. Thus, it is particularly important that these professionals are aware of the possibility of ischemic stroke occurring after even mild athletic injury. Childhood stroke may result from injuries sustained during athletic activities and should be considered when a child has acute focal neurologic signs.

The Role of Hydrogen Bonds Of The Azeotropic Hydrous Ethanol Fuel Composition To The Exhaust Emissions

NASA Astrophysics Data System (ADS)

Made Suarta, I.; Nyoman Gede Baliarta, I.; Sopan Rahtika, I. P. G.; Wijaya Sunu, Putu

2018-01-01

In this study observed the role of hydrogen bonding to the composition of exhaust emissions which is produced hydrous ethanol fuel (95.5% v). Testing is done by using single cylinder four stroke motor engine. The composition of exhaust gas emissions is tested using exhaust gas analyzer on lean and stoichiometry mixer. The exhaust emissions produced by anhydrous ethanol were also tested. The composition of emissions produced by that two fuels is compared. The results showed CO emissions levels produced by hydrous ethanol are slightly higher than anhydrous ethanol in stoichiometric mixtures. But the composition of CO hydrous ethanol emissions is lower in the lean mix. If lean the mixer the different in the composition of emissions is increasing. On hydrous ethanol emission CO2 content little bit lower on the stoichiometric mixer and higher on the lean mixture. Exhaust emissions of ethanol fuel also produce O2. O2 hydrous ethanol emissions is higher than anhydrous ethanol fuel.

Heat transfer to throat tubes in a square-chambered rocket engine at the NASA Lewis Research Center

NASA Technical Reports Server (NTRS)

Nesbitt, James A.; Brindley, William J.

1989-01-01

A gaseous H2/O2 rocket engine was constructed at the NASA-Lewis to provide a high heat flux source representative of the heat flux to the blades in the high pressure fuel turbopump (HPFTP) during startup of the space shuttle main engines. The high heat flux source was required to evaluate the durability of thermal barrier coatings being investigated for use on these blades. The heat transfer, and specifically, the heat flux to tubes located at the throat of the test rocket engine was evaluated and compared to the heat flux to the blades in the HPFTP during engine startup. Gas temperatures, pressures and heat transfer coefficients in the test rocket engine were measured. Near surface metal temperatures below thin thermal barrier coatings were also measured at various angular orientations around the throat tube to indicate the angular dependence of the heat transfer coefficients. A finite difference model for a throat tube was developed and a thermal analysis was performed using the measured gas temperatures and the derived heat transfer coefficients to predict metal temperatures in the tube. Near surface metal temperatures of an uncoated throat tube were measured at the stagnation point and showed good agreement with temperatures predicted by the thermal model. The maximum heat flux to the throat tube was calculated and compared to that predicted for the leading edge of an HPFTP blade. It is shown that the heat flux to an uncooled throat tube is slightly greater than the heat flux to an HPFTP blade during engine startup.

Compact high-speed MWIR spectrometer applied to monitor CO2 exhaust dynamics from a turbojet engine

NASA Astrophysics Data System (ADS)

Linares-Herrero, R.; Vergara, G.; Gutiérrez Álvarez, R.; Fernández Montojo, C.; Gómez, L. J.; Villamayor, V.; Baldasano Ramírez, A.; Montojo, M. T.; Archilla, V.; Jiménez, A.; Mercader, D.; González, A.; Entero, A.

2013-05-01

Dfgfdg Due to international environmental regulations, aircraft turbojet manufacturers are required to analyze the gases exhausted during engine operation (CO, CO2, NOx, particles, unburned hydrocarbons (aka UHC), among others).Standard procedures, which involve sampling the gases from the exhaust plume and the analysis of the emissions, are usually complex and expensive, making a real need for techniques that allow a more frequent and reliable emissions measurements, and a desire to move from the traditional gas sampling-based methods to real time and non-intrusive gas exhaust analysis, usually spectroscopic. It is expected that the development of more precise and faster optical methods will provide better solutions in terms of performance/cost ratio. In this work the analysis of high-speed infrared emission spectroscopy measurements of plume exhaust are presented. The data was collected during the test trials of commercial engines carried out at Turbojet Testing Center-INTA. The results demonstrate the reliability of the technique for studying and monitoring the dynamics of the exhausted CO2 by the observation of the infrared emission of hot gases. A compact (no moving parts), high-speed, uncooled MWIR spectrometer was used for the data collection. This device is capable to register more than 5000 spectra per second in the infrared band ranging between 3.0 and 4.6 microns. Each spectrum is comprised by 128 spectral subbands with aband width of 60 nm. The spectrometer operated in a passive stand-off mode and the results from the measurements provided information of both the dynamics and the concentration of the CO2 during engine operation.

Attachment process in rocket-triggered lightning strokes

NASA Astrophysics Data System (ADS)

Wang, D.; Rakov, V. A.; Uman, M. A.; Takagi, N.; Watanabe, T.; Crawford, D. E.; Rambo, K. J.; Schnetzer, G. H.; Fisher, R. J.; Kawasaki, Z.-I.

1999-01-01

In order to study the lightning attachment process, we have obtained highly resolved (about 100 ns time resolution and about 3.6 m spatial resolution) optical images, electric field measurements, and channel-base current recordings for two dart leader/return-stroke sequences in two lightning flashes triggered using the rocket-and-wire technique at Camp Blanding, Florida. One of these two sequences exhibited an optically discernible upward-propagating discharge that occurred in response to the approaching downward-moving dart leader and connected to this descending leader. This observation provides the first direct evidence of the occurrence of upward connecting discharges in triggered lightning strokes, these strokes being similar to subsequent strokes in natural lightning. The observed upward connecting discharge had a light intensity one order of magnitude lower than its associated downward dart leader, a length of 7-11 m, and a duration of several hundred nanoseconds. The speed of the upward connecting discharge was estimated to be about 2 × 107 m/s, which is comparable to that of the downward dart leader. In both dart leader/return-stroke sequences studied, the return stroke was inferred to start at the point of junction between the downward dart leader and the upward connecting discharge and to propagate in both upward and downward directions. This latter inference provides indirect evidence of the occurrence of upward connecting discharges in both dart leader/return-stroke sequences even though one of these sequences did not have a discernible optical image of such a discharge. The length of the upward connecting discharges (observed in one case and inferred from the height of the return-stroke starting point in the other case) is greater for the event that is characterized by the larger leader electric field change and the higher return-stroke peak current. For the two dart leader/return-stroke sequences studied, the upward connecting discharge lengths are estimated to be 7-11 m and 4-7 m, with the corresponding return-stroke peak currents being 21 kA and 12 kA, and the corresponding leader electric field changes 30 m from the rocket launcher being 56 kV/m and 43 kV/m. Additionally, we note that the downward dart leader light pulse generally exhibits little variation in its 10-90% risetime and peak value over some tens of meters above the return-stroke starting point, while the following return-stroke light pulse shows an appreciable increase in risetime and a decrease in peak value while traversing the same section of the lightning channel. Our findings regarding (1) the initially bidirectional development of return-stroke process and (2) the relatively strong attenuation of the upward moving return-stroke light (and by inference current) pulse over the first some tens of meters of the channel may have important implications for return-stroke modeling.

ManTech Implementing a Strategy to Deliver Weapon Systems Affordability

DTIC Science & Technology

2010-11-01

Tile 2007 – Translational Friction Stir Welding 2006 – Uncooled Focal Plane Array Producibility 2006 – Engine Rotor Life Extension 2005...compelling ideas will continue to help drive our Department’s innovative engine and ensure our Nation maintains its competitive edge on the...Sheets Composite Vertical Stabilizer Apache AH-64 NAVY The Challenge: Butt welding exterior ship panels produces a weld protrusion that exceeds the

Variations on the Zilch Cycle

ERIC Educational Resources Information Center

Binder, P.-M.; Tanoue, C. K. S.

2013-01-01

Thermo dynamic cycles in introductory physics courses are usually made up from a small number of permutations of isothermal, adiabatic, and constant-pressure and volume quasistatic strokes, with the working fluid usually being an ideal gas. Among them we find the Carnot, Stirling, Otto, Diesel, and Joule-Brayton cycles; in more advanced courses,…

Development of an advanced uncooled 10-Gb DFB laser for volume manufacture

NASA Astrophysics Data System (ADS)

Burns, Gordon; Charles, Paul M.

2003-03-01

Optical communication systems operating at 10Gbit/s such as 10Gigabit Ethernet are becoming more and more important in Local Area Networks (LAN) and Metropolitan Area Networks (MAN). This market requires optical transceivers of low cost, size and power consumption. This drives a need for uncooled DFB lasers directly modulated at 10Gbit/s. This paper describes the development of a state of the art uncooled high speed DFB laser which is capable of being manufactured in high volume at the low cost demanded by the GbE market. A DFB laser was designed by developing technological building blocks within the 'conventional" InGaAsP materials system, using existing well proven manufacturing processes modules wherever possible, limiting the design risk to a few key areas where innovation was required. The temperature and speed performance of the InGaAsP SMQW active layer system was carefully optimized and then coupled with a low parasitic lateral confinement system. Using concurrent engineering, new processes were demonstrated to have acceptable process capability within a manufacturing fabrication environment, proving their ability to support high volume manufacturing requirements. The DFB laser fabricated was shown to operate at 100C chip temperature with an open eye at 10Gbit/s operation (with an extinction ratio >5dB). Up to 90C operation this DFB shows threshold current as low as 29mA, optical power as high as 13mW and it meets the 10Gb scaled Ethernet mask with extinction ratio >6dB. It was found that the high temperature dynamic behavior of these lasers could not be fully predicted from static test data. A production test strategy was therefore followed where equipment was designed to fully test devices/subassemblies at 100C and up to 20Gbit/s at key points in the product build. This facilitated the rapid optimisation of product yields upon manufacturing ramp up and minimization of product costs. This state of the art laser is now transferred into volume manufacture.

Tailored approaches to stroke health education (TASHE): study protocol for a randomized controlled trial.

PubMed

Ravenell, Joseph; Leighton-Herrmann, Ellyn; Abel-Bey, Amparo; DeSorbo, Alexandra; Teresi, Jeanne; Valdez, Lenfis; Gordillo, Madeleine; Gerin, William; Hecht, Michael; Ramirez, Mildred; Noble, James; Cohn, Elizabeth; Jean-Louis, Giardin; Spruill, Tanya; Waddy, Salina; Ogedegbe, Gbenga; Williams, Olajide

2015-04-19

Stroke is a leading cause of adult disability and mortality. Intravenous thrombolysis can minimize disability when patients present to the emergency department for treatment within the 3 - 4½ h of symptom onset. Blacks and Hispanics are more likely to die and suffer disability from stroke than whites, due in part to delayed hospital arrival and ineligibility for intravenous thrombolysis for acute stroke. Low stroke literacy (poor knowledge of stroke symptoms and when to call 911) among Blacks and Hispanics compared to whites may contribute to disparities in acute stroke treatment and outcomes. Improving stroke literacy may be a critical step along the pathway to reducing stroke disparities. The aim of the current study is to test a novel intervention to increase stroke literacy in minority populations in New York City. In a two-arm cluster randomized trial, we will evaluate the effectiveness of two culturally tailored stroke education films - one in English and one in Spanish - on changing behavioral intent to call 911 for suspected stroke, compared to usual care. These films will target knowledge of stroke symptoms, the range of severity of symptoms and the therapeutic benefit of calling 911, as well as address barriers to timely presentation to the hospital. Given the success of previous church-based programs targeting behavior change in minority populations, this trial will be conducted with 250 congregants across 14 churches (125 intervention; 125 control). Our proposed outcomes are (1) recognition of stroke symptoms and (2) behavioral intent to call 911 for suspected stroke, measured using the Stroke Action Test at the 6-month and 1-year follow-up. This is the first randomized trial of a church-placed narrative intervention to improve stroke outcomes in urban Black and Hispanic populations. A film intervention has the potential to make a significant public health impact, as film is a highly scalable and disseminable medium. Since there is at least one church in almost every neighborhood in the USA, churches have the ability and reach to play an important role in the dissemination and translation of stroke prevention programs in minority communities. NCT01909271 ; July 22, 2013.

Exploring the experiences of rehabilitated stroke survivors and stakeholders with regard to returning to work in South- West Nigeria.

PubMed

Soeker, Mogammad Shaheed; Olaoye, Olumide Ayoola

2017-01-01

Stroke has been identified as a global cause of neurological disability with a resultant burden shared not only by the survivor but also by society. The resumption of an individual's role as a worker after having a stroke, is an important rehabilitation goal. South-West Nigeria has experienced a high incidence and prevalence of stroke, leaving a quarter of survivors with severe disabilities and difficulties in community integration after rehabilitation. The study was aimed at exploring and describing the experiences of rehabilitated stroke survivors and perceptions of stakeholders about stroke survivors returning to work in South-West Nigeria. A qualitative research design was used to explore these experiences and perceptions from 19 participants, comprising nine stroke survivors, two key informants, who were rehabilitation specialists, and eight caregivers of the respective stroke survivors. The researcher made use of focus groups with the caregivers and semi-structured interviews with the stroke survivors and rehabilitation specialists. The data from the study were analysed using thematic analysis. Three themes emerged: Themes one and two described the barriers experienced by the stroke survivors on returning to work. Theme three described the factors that facilitated the resumption of the worker role. The study findings clearly depicted the many barriers experienced by stroke survivors and how these negatively impact their worker roles. Limited facilitatory factors exist to assist stroke survivors in regard to adapting to their worker roles. Promoting participation of stroke survivors in work emanating from government policies was deemed to be a necessary recommendation for the study. These policies were seen to be achievable if rehabilitation resources were improved.

Twelve-month experience of acute stroke thrombolysis in Christchurch, New Zealand: emergency department screening and acute stroke service treatment.

PubMed

Fink, John

2005-05-06

To determine the safety and efficiency of an acute stroke thrombolysis service in a New Zealand public hospital setting. A 12-month audit of patients referred to the Christchurch Hospital Stroke Thrombolysis Service (STS) between 1 April 2002 and 31 March 2003 was undertaken. Sixty-one patients were referred to the STS during the study period, of whom 16 were treated with tissue plasminogen activator (t-PA). For treated patients, the median time from stroke onset to hospital presentation was 60 minutes, 'door-to-CT' time was 60 minutes, and the 'door-to-needle' time was 99 minutes. Minor protocol violations were recorded in two patients, but did not influence outcome. No patient was treated after 3 hours of stroke onset. Intracerebral haemorrhage occurred in two patients: one patient was significantly improved compared with pre-treatment status; a minor temporary deterioration occurred in the other patient. Eight of 16 patients had improved by 4 or more points on the NIH Stroke Scale Score at 24 hours. Acute stroke thrombolysis can be delivered safely and in accordance with internationally accepted guidelines using the Christchurch Hospital STS model of emergency department screening and acute stroke service treatment. Further improvements in performance of the STS remain possible.

Stroke survivors with severe mental illness: Are they at-risk for increased non-psychiatric hospitalizations?

PubMed

Lilly, Flavius Robert; Culpepper, Joel; Stuart, Mary; Steinwachs, Donald

2017-01-01

This study examined outcomes for two groups of stroke survivors treated in Veteran Health Administration (VHA) hospitals, those with a severe mental illness (SMI) and those without prior psychiatric diagnoses, to examine risk of non-psychiatric medical hospitalizations over five years after initial stroke. This retrospective cohort study included 523 veterans who survived an initial stroke hospitalization in a VHA medical center during fiscal year 2003. The survivors were followed using administrative data documenting inpatient stroke treatment, patient demographics, disease comorbidities, and VHA hospital admissions. Multivariate Poisson regression was used to examine the relationship between patients with and without SMI diagnosis preceding the stroke and their experience with non-psychiatric medical hospitalizations after the stroke. The study included 100 patients with SMI and 423 without SMI. Unadjusted means for pre-stroke non-psychiatric hospitalizations were higher (p = 0.0004) among SMI patients (1.47 ± 0.51) compared to those without SMI (1.00 ± 1.33), a difference which persisted through the first year post-stroke (SMI: 2.33 ± 2.46; No SMI: 1.74 ± 1.86; p = 0.0004). Number of non-psychiatric hospitalizations were not significantly different between the two groups after adjustment for patient sociodemographic, comorbidity, length of stay and inpatient stroke treatment characteristics. Antithrombotic medications significantly lowered risk (OR = 0.61; 95% CI: 0.49-0.73) for stroke-related readmission within 30 days of discharge. No significant differences in medical hospitalizations were present after adjusting for comorbid and sociodemographic characteristics between SMI and non-SMI stroke patients in the five-year follow-up. However, unadjusted results continue to draw attention to disparities, with SMI patients experiencing more non-psychiatric hospitalizations both prior to and up to one year after their initial stroke. Additionally, stroke survivors discharged on antithrombotic medications were at lower risk of re-admission within 30 days suggesting the VHA should continue to focus on effective stroke management irrespective of SMI.

Apipuncture treatment for central post-stroke pain.

PubMed

Yun, Sang Pil; Sun, Bong Chul

2010-02-01

The objective of this study was to assess the effectiveness of apipuncture treatment for central post-stroke pain. Two (2) female subjects with central post-stroke pain were treated with apipuncture. Both patients experienced a reduction in the intensity of pain after receiving apipuncture treatment without adverse effects. Apipuncture is an effective and safe intervention to treat central post-stroke pain.

A Comparative Analysis of Swimming Styles in Competitive Swimming

NASA Astrophysics Data System (ADS)

von Loebbecke, Alfred; Mittal, Rajat; Gupta, Varun; Mark, Russell

2007-11-01

High-fidelity numerical simulations are being used to conduct a critical evaluation of swimming strokes in competitive swimming. We combine computational fluid dynamics (CFD), laser body scans, animation software, and video footage to develop accurate models of Olympic level swimmers and use these to examine contrasting styles of the dolphin kick as well as the arm strokes in back and front crawl stroke. In the dolphin kick, the focus is on examining the effects of Strouhal number, kick amplitude, frequency, and technique on thrust production. In the back stroke, we examine the performance of the so called ``flat stroke'' versus the ``deep catch,'' The most important aspect that separates the two major types of back stroke is the alignment or angle of attack of the palm during the stroke. In one style of front crawl arm stroke, there is greater elbow joint flexion, shoulder abduction and sculling whereas the other style consists of a straight arm pull dominated by simple shoulder flexion. Underlying the use of these two styles is the larger and more fundamental issue of the role of lift versus drag in thrust production and we use the current simulations to examine this issue in detail.

Pirandello's analogy: a source for a better understanding of the social impact of stroke.

PubMed

van Haaren, M A C; Lawrence, M; Goossens, P H; van den Bossche, B; Wermer, M J H; Kaptein, A A

2012-01-01

Suffering a stroke has major implications for the patient. To understand human suffering, one should understand society. Pirandello described society as a higher entity than the individual, thereby justifying human adaptability to society. We explore a qualitative finding that suggests that social trends may influence how stroke patients prioritize aspects of their rehabilitation. We compare a contemporary patient's experience of stroke recovery with that of a fictional character from the works of Luigi Pirandello. Both patients had two main residual symptoms: hemiparesis and aphasia. The rehabilitation priorities of the two patients differed, and appeared to reflect the contemporaneous demands of society. Mobility was prioritized in 1910; communication was prioritized in 2010. However, essential aspects of 'being a stroke patient' remained unchanged; both patients retained a sense of self and both coped emotionally by being hopeful. We conclude that stroke patients respond to society's contemporaneous demands and expectations. Currently, society demands participation in a large social environment and this is reflected in stroke patients' priorities. This analogy could enable medical professionals to better understand the social impact of stroke, and consequently offer appropriate interventions to improve rehabilitation outcomes for individual patients. Copyright © 2012 S. Karger AG, Basel.

Crank case scavenging of two-stroke-cycle engines

NASA Technical Reports Server (NTRS)

List, Hans

1929-01-01

This report presents the results of tests on two-stroke-cycle Diesel engines to determine the efficiency of the crank case scavenging pump. It was determined that efficiencies were between 95 and 100%.

Recent Development of the Two-Stroke Engine. II - Design Features. 2; Design Features

NASA Technical Reports Server (NTRS)

Zeman, J.

1945-01-01

Completing the first paper dealing with charging methods and arrangements, the present paper discusses the design forms of two-stroke engines. Features which largely influence piston running are: (a) The shape and surface condition of the sliding parts. (b) The cylinder and piston materials. (c) Heat conditions in the piston, and lubrication. There is little essential difference between four-stroke and two-stroke engines with ordinary pistons. In large engines, for example, are always found separately cast or welded frames in which the stresses are taken up by tie rods. Twin piston and timing piston engines often differ from this design. Examples can be found in many engines of German or foreign make. Their methods of operation will be dealt with in the third part of the present paper, which also includes the bibliography. The development of two-stroke engine design is, of course, mainly concerned with such features as are inherently difficult to master; that is, the piston barrel and the design of the gudgeon pin bearing. Designers of four-stroke engines now-a-days experience approximately the same difficulties, since heat stresses have increased to the point of influencing conditions in the piston barrel. Features which notably affect this are: (a) The material. (b) Prevailing heat conditions.

International Survey on the Management of Wake-Up Stroke.

PubMed

de Castro-Afonso, Luís Henrique; Nakiri, Guilherme Seizem; Pontes-Neto, Octávio Marques; dos Santos, Antônio Carlos; Abud, Daniel Giansante

2016-01-01

Patients who wake up having experienced a stroke while asleep represent around 20% of acute stroke admissions. According to international guidelines for the management of acute stroke, patients presenting with wake-up stroke are not currently eligible to receive revascularization treatments. In this study, we aimed to assess the opinions of stroke experts about the management of patients with wake-up stroke by using an international multicenter electronic survey. This study consisted of 8 questions on wake-up stroke treatment. Two hundred invitations to participate in the survey were sent by e-mail. Fifty-nine participants started the survey, 4 dropped out before completing it, and 55 completed the full questionnaire. We had 55 participants from 22 countries. In this study, most stroke experts recommended a recanalization treatment for wake-up stroke. However, there was considerable disagreement among experts regarding the best brain imaging method and the best recanalization treatment. The results of ongoing randomized trials on wake-up stroke are urgently needed.

Evolution of on-road vehicle exhaust emissions in Delhi

NASA Astrophysics Data System (ADS)

Goel, Rahul; Guttikunda, Sarath K.

2015-03-01

For a 40-year horizon (1990-2030), on-road vehicle exhaust emissions were evaluated, retrospectively and prospectively, for the largest urban agglomeration in India - the Greater Delhi region with a combined population of 22 million in 2011 (Delhi along with Ghaziabad, Noida, Greater Noida, Faridabad and Gurgaon). Emissions of particulate matter, sulfur dioxide, carbon monoxide and volatile organic compounds (VOCs) reached their peak during late 1990s through early 2000s after which they reduced significantly through year 2012. On the other hand, nitrogen oxides (NOx) and carbon dioxide show an increasing trend. The most reduction in emissions between 1998 and 2012 occurred as a result of implementation of four sets of vehicular emission standards, removal of lead, reduction of sulfur content, mandatory retirement of older commercial vehicles, and conversion of diesel and petrol run public transport vehicles to compressed natural gas. In addition, changes in the vehicular technology have also contributed to controlling emissions especially in case of auto-rickshaws and motorized two-wheelers, which changed from two-stroke to four-stroke. The rising trend of NOx along with the presence of VOCs indicates increasing tendency to form ground-level ozone and as a result, smog in the region. We predict that the current regime of vehicle technology, fuel standards, and high growth rate of private vehicles, is likely to nullify all the past emission reductions by the end of 2020s.

The principal motions involved in the coupling mechanism of the recovery stroke of the myosin motor.

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

Mesentean, Sidonia; Koppole, Sampath; Smith, Jeremy C

2007-03-01

Muscle contraction is driven by a cycle of conformational changes in the myosin II head. After myosin binds ATP and releases from the actin fibril, myosin prepares for the next power stroke by rotating back the converter domain that carries the lever arm by 60{sup o}. This recovery stroke is coupled to the activation of myosin ATPase by a mechanism that is essential for an efficient motor cycle. The mechanics of this coupling have been proposed to occur via two distinct and successive motions of the two helices that hold the converter domain: in a first phase a seesaw motionmore » of the relay helix, followed by a piston-like motion of the SH1 helix in a second phase. To test this model, we have determined the principal motions of these structural elements during equilibrium molecular dynamics simulations of the crystallographic end states of the recovery-stroke by using principal component analysis. This reveals that the only principal motions of these two helices that make a large-amplitude contribution towards the conformational change of the recovery stroke are indeed the predicted seesaw and piston motions. Moreover, the results demonstrate that the seesaw motion of the relay helix dominates in the dynamics of the pre-recovery stroke structure, but not in the dynamics of the post-recovery stroke structure, and vice versa for the piston motion of the SH1 helix. This is consistent with the order of the proposed two-phase model for the coupling mechanism of the recovery stroke. Molecular movies of these principal motions are available at http://www.iwr.uni-heidelberg.de/groups/biocomp/fischer.« less

Mechanism of transient force augmentation varying with two distinct timescales for interacting vortex rings

NASA Astrophysics Data System (ADS)

Fu, Zhidong; Qin, Suyang; Liu, Hong

2014-01-01

The dynamics of dual vortex ring flows is studied experimentally and numerically in a model system that consists of a piston-cylinder apparatus. The flows are generated by double identical strokes which have the velocity profile characterized by the sinusoidal function of half the period. By calculating the total wake impulse in two strokes in the experiments, it is found that the average propulsive force increases by 50% in the second stroke for the sufficiently small stroke length, compared with the first stroke. In the numerical simulations, two types of transient force augmentation are revealed, there being the transient force augmentation for the small stroke lengths and the absolute transient force augmentation for the large stroke lengths. The relative transient force augmentation increases to 78% for L/D = 1, while the absolute transient force augmentation for L/D = 4 is twice as much as that for L/D = 1. Further investigation demonstrates that the force augmentation is attributed to the interaction between vortex rings, which induces transport of vortex impulse and more evident fluid entrainment. The critical situation of vortex ring separation is defined and indicated, with vortex spacing falling in a narrow gap when the stroke lengths vary. A new model is proposed concerning the limiting process of impulse, further suggesting that apart from vortex formation timescale, vortex spacing should be interpreted as an independent timescale to reflect the dynamics of vortex interaction.

Xenon is an inhibitor of tissue-plasminogen activator: adverse and beneficial effects in a rat model of thromboembolic stroke

PubMed Central

David, Hélène N; Haelewyn, Benoît; Risso, Jean-Jacques; Colloc'h, Nathalie; Abraini, Jacques H

2010-01-01

Preclinical evidence in rodents has proven that xenon may be a very promising neuroprotective agent for treating acute ischemic stroke. This has led to the general thinking that clinical trials with xenon could be initiated in acute stroke patients in a next future. However, an unappreciated physicochemical property of xenon has been that this gas also binds to the active site of a series of serine proteases. Because the active site of serine proteases is structurally conserved, we have hypothesized and investigated whether xenon may alter the catalytic efficiency of tissue-type plasminogen activator (tPA), a serine protease that is the only approved therapy for acute ischemic stroke today. Here, using molecular modeling and in vitro and in vivo studies, we show (1) xenon is a tPA inhibitor; (2) intraischemic xenon dose dependently inhibits tPA-induced thrombolysis and subsequent reduction of ischemic brain damage; (3) postischemic xenon virtually suppresses ischemic brain damage and tPA-induced brain hemorrhages and disruption of the blood–brain barrier. Taken together, these data indicate (1) xenon should not be administered before or together with tPA therapy; (2) xenon could be a golden standard for treating acute ischemic stroke if given after tPA-induced reperfusion, with both unique neuroprotective and antiproteolytic (anti-hemorrhaging) properties. PMID:20087367

Sensitivity and Specificity of an Adult Stroke Screening Tool in Childhood Ischemic Stroke.

PubMed

Neville, Kerri; Lo, Warren

2016-05-01

There are frequent delays in the diagnosis of acute pediatric ischemic stroke. A screening tool that could increase the suspicion of acute ischemic stroke could aid early recognition and might improve initial care. An earlier study reported that children with acute ischemic stroke have signs that can be recognized with two adult stroke scales. We tested the hypothesis that an adult stroke scale could distinguish children with acute ischemic stroke from children with acute focal neurological deficits not due to stroke. We retrospectively applied an adult stroke scale to the recorded examinations of 53 children with acute symptomatic acute ischemic stroke and 53 age-matched control subjects who presented with focal neurological deficits. We examined the sensitivity and specificity of the stroke scale and the occurrence of acute seizures as predictors of stroke status. The total stroke scale did not differentiate children with acute ischemic stroke from those who had acute deficits from nonstroke causes; however, the presence of arm weakness was significantly associated with stroke cases. Acute seizures were significantly associated with stroke cases. An adult stroke scale is not sensitive or specific to distinguish children with acute ischemic stroke from those with nonstroke focal neurological deficits. The development of a pediatric acute ischemic stroke screening tool should include arm weakness and perhaps acute seizures as core elements. Such a scale must account for the limitations of language in young or intellectually disabled children. Copyright © 2016 Elsevier Inc. All rights reserved.

EMISSIONS FROM TWO OUTBOARD ENGINES OPERATING ON REFORMULATED GASOLINE CONTAINING MTBE

EPA Science Inventory

Air and water pollutant emissions were measured from two 9.9 HP outboard engines: a two-stroke Evinrude and its four-stroke Honda counterpart. In addition to the measurement of regulated air pollutants, speciated organic pollutants and particulate matter emissions were determi...

Rural Organization of Australian Stroke Teams: Emergency Department project.

PubMed

Wright, A; McGrail, M; Disler, P

2008-08-01

Many junior doctors have poor stroke assessment skills. Although major efforts have gone in to changing the attitudes of clinicians to stroke through the development of guidelines and implementation strategies, the most important step may be to make sure that medical schools include appropriate teaching of this important topic in their curricula. The Rural Organization of Australian Stroke Teams Emergency Department (ROASTED) project sought to determine the effectiveness of a practical intervention to improve the assessment and education of stroke knowledge among our junior emergency department doctors. We used a prospective before and after study of two separate cohorts (intervention vs no intervention) to assess the stroke knowledge of our junior emergency department doctors and to test the effectiveness of an educational intervention. The project took place at five sites in rural Victoria in November 2006. Both cohorts undertook the same two validated quizzes 1 month apart. At the intervention sites two 1-h tutorials were conducted between the quizzes and participants were encouraged to use a web-based educational tool. Pre-project stroke knowledge was shown to be poor at all of the participating sites. At the sites where no intervention took place no improvement in knowledge was shown (z = 0.83, P = 0.41, two-sided Mann-Whitney U-test). The median score for quiz 1 was 8.1 (41%, interquartile range (IQR) 6.5-9.4) and for quiz 2, 7.2 (36%, IQR 5.1-9.3). At the intervention sites, participants significantly improved their stroke knowledge between quiz 1 and quiz 2 (z = 4.75, P < 0.001). The median score for quiz 1 in this cohort was 8.3 (42%, IQR 6.5-10.0) and for quiz 2, 12.8 (64%, IQR 12.0-14.8). This project showed that junior doctors have an inadequate knowledge of stroke and that among our junior emergency department doctors there is a need for the ROASTED intervention and other innovative educational measures.

Hydrogen Gas Inhalation Treatment in Acute Cerebral Infarction: A Randomized Controlled Clinical Study on Safety and Neuroprotection.

PubMed

Ono, Hirohisa; Nishijima, Yoji; Ohta, Shigeo; Sakamoto, Masaki; Kinone, Kazunori; Horikosi, Tohru; Tamaki, Mituyuki; Takeshita, Hirosi; Futatuki, Tomoko; Ohishi, Wataru; Ishiguro, Taichi; Okamoto, Saori; Ishii, Shou; Takanami, Hiroko

2017-11-01

Molecular hydrogen (H 2 ) acts as a therapeutic antioxidant. Inhalation of H 2 gas (1-4%) was effective for the improvement of cerebral infarction in multiple animal experiments. Thus, for actual applications, a randomized controlled clinical study is desired to evaluate the effects of inhalation of H 2 gas. Here, we evaluate the H 2 treatment on acute cerebral infarction. Through this randomized controlled clinical study, we assessed the safety and effectiveness of H 2 treatment in patients with cerebral infarction in an acute stage with mild- to moderate-severity National Institute of Health Stroke Scale (NIHSS) scores (NIHSS = 2-6). We enrolled 50 patients (25 each in the H 2 group and the control group) with a therapeutic time window of 6 to 24 hours. The H 2 group inhaled 3% H 2 gas (1 hour twice a day), and the control group received conventional intravenous medications for the initial 7 days. The evaluations included daily vital signs, NIHSS scores, physical therapy indices, weekly blood chemistry, and brain magnetic resonance imaging (MRI) scans over the 2-week study period. The H 2 group showed no significant adverse effects with improvements in oxygen saturation. The following significant effects were found: the relative signal intensity of MRI, which indicated the severity of the infarction site, NIHSS scores for clinically quantifying stroke severity, and physical therapy evaluation, as judged by the Barthel Index. H 2 treatment was safe and effective in patients with acute cerebral infarction. These results suggested a potential for widespread and general application of H 2 gas. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Meeting stroke survivors' perceived needs: a qualitative study of a community-based exercise and education scheme.

PubMed

Reed, Mary; Harrington, Rachel; Duggan, Aine; Wood, Victorine A

2010-01-01

A qualitative study using a phenomenological approach, to explore stroke survivors' needs and their perceptions of whether a community stroke scheme met these needs. Semi-structured in-depth interviews of 12 stroke survivors, purposively selected from participants attending a new community stroke scheme. Interpretative phenomenological analysis of interviews by two researchers independently. Participants attending the community stroke scheme sought to reconstruct their lives in the aftermath of their stroke. To enable this they needed internal resources of confidence and sense of purpose to 'create their social self', and external resources of 'responsive services' and an 'informal support network', to provide direction and encouragement. Participants felt the community stroke scheme met some of these needs through exercise, goal setting and peer group interaction, which included social support and knowledge acquisition. Stroke survivors need a variety of internal and external resources so that they can rebuild their lives positively post stroke. A stroke-specific community scheme, based on exercise, life-centred goal setting, peer support and knowledge acquisition, is an external resource that can help with meeting some of the stroke survivor's needs.

Factors associated with hospital arrival time after the onset of stroke symptoms: A cross-sectional study at two teaching hospitals in Harare, Zimbabwe.

PubMed

Seremwe, Farayi; Kaseke, Farayi; Chikwanha, Theodora M; Chikwasha, Vasco

2017-06-01

Late presentation to hospital after onset of stroke affects management and outcomes of the patients. This study aimed to determine the factors associated with time taken to present to hospital after the onset of acute stroke symptoms. A descriptive cross sectional study was conducted at two teaching hospitals in Zimbabwe. Participants included patients admitted with stroke and their relatives. A self-administered questionnaire was used to collect information on history of stroke occurrence and time taken to present to hospital. Data was analysed for means, frequencies, percentages and Odds ratios. Less than half (33%) of the participants were able to recognize symptoms of stroke. Not having money to pay for hospital bills was a predictor of late hospital presentation (OR =6.64; 95% CI, (2.05-21.53); p=0.002). The other factors, though not statistically significant included not perceiving stroke as a serious illness (OR = 2.43; 95% CI (0.78-5.51); p=0.083) and unavailability of transport (OR=2.33; 95% CI (0.71-7.56); p=0.161). Predictors for early presentation included receiving knowledge about stroke from the community (OR=0.46; 95% CI (0.15-1.39); p=0.170); seeking help at the hospital (OR=0.50; 95% CI (0.18-1.37); p=0.177) and having a stroke while at the workplace (OR =0.46; 95% CI (0.08-2.72); p=0.389). Regarding stroke as an emergency that does not require prerequisite payment for services at hospitals and improved community awareness on stroke may improve time taken to present to hospital after the onset of stroke symptoms.

Agreement between routine electronic hospital discharge and Scottish Stroke Care Audit (SSCA) data in identifying stroke in the Scottish population.

PubMed

Turner, Melanie; Barber, Mark; Dodds, Hazel; Dennis, Martin; Langhorne, Peter; Macleod, Mary-Joan

2015-12-30

In Scotland all non-obstetric, non-psychiatric acute inpatient and day case stays are recorded by an administrative hospital discharge database, the Scottish Morbidity Record (SMR01). The Scottish Stroke Care Audit (SSCA) collects data from all hospitals managing acute stroke in Scotland to support and improve quality of stroke care. The aim was to assess whether there were discrepancies between these data sources for admissions from 2010 to 2011. Records were matched when admission dates from the two data sources were within two days of each other and if an International Classification of Diseases (ICD) code of I61, I63, I64, or G45 was in the primary or secondary diagnosis field on SMR01. We also carried out a linkage analysis followed by a case-note review within one hospital in Scotland. There were a total of 22 416 entries on SSCA and 22 200 entries on SMR01. The concordance between SSCA and SMR01 was 16 823. SSCA contained 5593 strokes that were not present in SMR01, whereas SMR01 contained 185 strokes that were not present in SSCA. In the case-note review the concordance was 531, with SSCA containing 157 strokes that were not present in SMR01 and SMR01 containing 32 strokes that were not present in SSCA. When identifying strokes, hospital administrative discharge databases should be used with caution. Our results demonstrate that SSCA most accurately represents the number of strokes occurring in Scotland. This resource is useful for determining the provision of adequate patient care, stroke services and resources, and as a tool for research.

Ischemic stroke in patients with cancer: is it different from usual strokes?

PubMed

Lee, Eun-Jae; Nah, Hyun-Wook; Kwon, Joo-Young; Kang, Dong-Wha; Kwon, Sun U; Kim, Jong S

2014-06-01

It remains unclear whether the characteristics of ischemic stroke in patients with cancer (ISC) differ from usual ischemic strokes (non-ISC). Although a small number of studies have been conducted to characterize ISC, the status of cancer has rarely been considered seriously. We aimed to investigate the features of ISC according to the status of cancer, and compare their characteristics with those of non-ISC. We assessed and classified 204 ISC patients into two groups: 104 with active (ISC-active) and 100 with inactive (ISC-inactive) cancer. For each ISC patient, two age- and gender-matched ischemic stroke patients without history of cancer were selected as non-ISC control subjects. We compared the clinical/laboratory data, stroke mechanisms, and diffusion weighted imaging (DWI) lesion patterns between ISC-active and non-ISC patients, and between ISC-inactive and non-ISC patients. ISC-active patients demonstrated higher C-reactive protein (CRP) and D-dimer, more frequent cryptogenic stroke and patterns of multiple DWI lesions (in bilateral anterior or in anterior and posterior circulations), and less prevalent conventional risk factors than non-ISC patients, while ISC-inactive patients revealed no such marked differences. Among ISC-active patients, both elevated CRP and D-dimer levels were associated with cryptogenic mechanism and multiple lesion patterns. Furthermore, ISC-active patients with cryptogenic strokes tended to have multiple lesion patterns and metastasis. ISC-active, but not ISC-inactive, is distinct in terms of risk factors, stroke mechanisms, and lesion patterns. Chronic inflammation and an activated coagulation system may contribute to the pathogenic mechanism of strokes, the extent of each depending on the activity and severity of cancer. © 2013 The Authors. International Journal of Stroke © 2013 World Stroke Organization.

49 CFR 571.131 - Standard No. 131; School bus pedestrian safety devices.

Code of Federal Regulations, 2014 CFR

2014-10-01

... least 150 mm (5.9 inches) in height. The letters shall have a stroke width of at least 20 mm (0.79... contained within each letter, the net stroke width (stroke width minus the width of the lamp(s)) of each....2.1. All lamps shall be positioned in one of the two following ways: (1) centered within the stroke...

49 CFR 571.131 - Standard No. 131; School bus pedestrian safety devices.

Code of Federal Regulations, 2012 CFR

2012-10-01

... least 150 mm (5.9 inches) in height. The letters shall have a stroke width of at least 20 mm (0.79... contained within each letter, the net stroke width (stroke width minus the width of the lamp(s)) of each....2.1. All lamps shall be positioned in one of the two following ways: (1) centered within the stroke...

49 CFR 571.131 - Standard No. 131; School bus pedestrian safety devices.

Code of Federal Regulations, 2013 CFR

2013-10-01

... least 150 mm (5.9 inches) in height. The letters shall have a stroke width of at least 20 mm (0.79... contained within each letter, the net stroke width (stroke width minus the width of the lamp(s)) of each....2.1. All lamps shall be positioned in one of the two following ways: (1) centered within the stroke...

49 CFR 571.131 - Standard No. 131; School bus pedestrian safety devices.

Code of Federal Regulations, 2011 CFR

2011-10-01

... least 150 mm (5.9 inches) in height. The letters shall have a stroke width of at least 20 mm (0.79... contained within each letter, the net stroke width (stroke width minus the width of the lamp(s)) of each....2.1. All lamps shall be positioned in one of the two following ways: (1) centered within the stroke...

76 FR 10907 - Agency Forms Undergoing Paperwork Reduction Act Review

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-28

... Project Division of Heart Disease and Stroke Prevention Management Information System--Revision--National... Prevention (CDC). Background and Brief Description CDC's Division of Heart Disease and Stroke Prevention... two programs: The National Heart Disease and Stroke Prevention Program (NHDSPP), and the Well...

Lack of association between two key SNPs on chromosome 12p13 and ischemic stroke in Chinese Uyghur population.

PubMed

Tong, Yeqing; Zhan, Faxian; Han, Jinjun; Zhang, Yanwei; Yin, Xiaoxu; Geng, Yijie; Hou, Shuangyi; Ye, Jianjun; Guan, Xuhua; Han, Shenhong; Wang, Yunxia; Mason, Katherine A; Lu, Zuxun; Liu, Jiafa; Cheng, Jinquan

2012-12-15

Recent genome-wide association studies (GWAS) have identified two key SNPs (rs11833579 and rs12425791) on chromosome 12p13 that were significantly associated with stroke in Caucasians. However, the validity of the association has remained controversial. We performed genetic association analyses in a very unique population which has 60% European ancestry and 40% East Asian ancestry. No significant association between these two SNPs and ischemic stroke was detected in this Chinese Uyghur population. Copyright © 2012 Elsevier B.V. All rights reserved.

Demand charge reduction with digester gas

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

Not Available

1985-02-01

This paper examines a rather sophisticated treatment system in the city of Whitewater, Wisconsin. The power generated is used to trim utility peak power loads and demand charges. Power is derived from four Waukesha VHP 3600G engine generator sets with provisions for a fifth as growth requires. The engine is a Waukesha F3521GU spark ignited, six-cylinder gas engine with 9.375 in. x 8.50 bore and stroke driving a Kato 350 kW generator rated at 480/277 volts and 1200 rpm. Normal operation is to reduce the peak demand.

Increasing the volumetric efficiency of Diesel engines by intake pipes

NASA Technical Reports Server (NTRS)

List, Hans

1933-01-01

Development of a method for calculating the volumetric efficiency of piston engines with intake pipes. Application of this method to the scavenging pumps of two-stroke-cycle engines with crankcase scavenging and to four-stroke-cycle engines. The utility of the method is demonstrated by volumetric-efficiency tests of the two-stroke-cycle engines with crankcase scavenging. Its practical application to the calculation of intake pipes is illustrated by example.

The Performance of Chrome-Coated Copper as Metallic Catalytic Converter to Reduce Exhaust Gas Emissions from Spark-Ignition Engine

NASA Astrophysics Data System (ADS)

Warju; Harto, S. P.; Soenarto

2018-01-01

One of the automotive technologies to reduce exhaust gas emissions from the spark-ignition engine (SIE) is by using a catalytic converter. The aims of this research are firstly to conduct a metallic catalytic converter, secondly to find out to what extend chrome-coated copper plate (Cu+Cr) as a catalyst is efficient. To measure the concentration of carbon monoxide (CO) and hydrocarbon (HC) on the frame there are two conditions required. First is when the standard condition, and second is when Cu+Cr metallic catalytic converter is applied using exhaust gas analyzer. Exhaust gas emissions from SIE are measured by using SNI 19-7118.1-2005. The testing of CO and HC emissions were conducted with variable speed to find the trend of exhaust gas emissions from idle speed to high speed. This experiment results in the fact that the use of Cu+Cr metallic catalytic converter can reduce the production of CO and HC of a four-stroke gasoline engine. The reduction of CO and HC emission are 95,35% and 79,28%. Using active metal catalyst in form of metallic catalytic converter, it is gained an optimum effective surface of a catalyst which finally is able to decrease the amount of CO and HC emission significantly in every spinning happened in the engine. Finally, this technology can be applied to the spark ignition engine both car and motorcycle to support blue sky program in Indonesia.

Allied health clinicians using translational research in action to develop a reliable stroke audit tool.

PubMed

Abery, Philip; Kuys, Suzanne; Lynch, Mary; Low Choy, Nancy

2018-05-23

To design and establish reliability of a local stroke audit tool by engaging allied health clinicians within a privately funded hospital. Design: Two-stage study involving a modified Delphi process to inform stroke audit tool development and inter-tester reliability. Allied health clinicians. A modified Delphi process to select stroke guideline recommendations for inclusion in the audit tool. Reliability study: 1 allied health representative from each discipline audited 10 clinical records with sequential admissions to acute and rehabilitation services. Recommendations were admitted to the audit tool when 70% agreement was reached, with 50% set as the reserve agreement. Inter-tester reliability was determined using intra-class correlation coefficients (ICCs) across 10 clinical records. Twenty-two participants (92% female, 50% physiotherapists, 17% occupational therapists) completed the modified Delphi process. Across 6 voting rounds, 8 recommendations reached 70% agreement and 2 reached 50% agreement. Two recommendations (nutrition/hydration; goal setting) were added to ensure representation for all disciplines. Substantial consistency across raters was established for the audit tool applied in acute stroke (ICC .71; range .48 to .90) and rehabilitation (ICC.78; range .60 to .93) services. Allied health clinicians within a privately funded hospital generally agreed in an audit process to develop a reliable stroke audit tool. Allied health clinicians agreed on stroke guideline recommendations to inform a stroke audit tool. The stroke audit tool demonstrated substantial consistency supporting future use for service development. This process, which engages local clinicians, could be adopted by other facilities to design reliable audit tools to identify local service gaps to inform changes to clinical practice. © 2018 John Wiley & Sons, Ltd.

Comparison of cardiovascular risk factors and survival in patients with ischemic or hemorrhagic stroke.

PubMed

Henriksson, Karin M; Farahmand, Bahman; Åsberg, Signild; Edvardsson, Nils; Terént, Andreas

2012-06-01

Differences in risk factor profiles between patients with ischemic and hemorrhagic stroke may have an impact on subsequent mortality. To explore cardiovascular disease risk factors, including the CHADS(2) score, with survival after ischemic or hemorrhagic stroke. Between 2001 and 2005, 87 111 (83%) ischemic stroke, 12 497 (12%) hemorrhagic stroke, and 5435 (5%) patients with unspecified stroke were identified in the Swedish Stroke Register. Data on gender, age, and cardiovascular disease risk factors were linked to the Swedish Hospital Discharge and Cause of Death Registers. Adjusted odds and hazard ratios and 95% confidence interval were calculated using logistic and Cox proportional hazard regression models. Hemorrhagic stroke patients were younger than ischemic stroke patients. All cardiovascular disease risk factors studied, alone or combined in the CHADS(2) score, were associated with higher odds ratios for ischemic stroke vs. hemorrhagic stroke. Higher CHADS(2) scores and all studied risk factors except hypertension were associated with higher odds ratio for death by ischemic stroke than hemorrhagic stroke. Ischemic stroke was associated with lower early mortality (within 30 days) vs. hemorrhagic stroke (hazard ratio = 0·28, confidence interval 0·27 to 0·29). Patients with hemorrhagic stroke had a higher risk of dying within the first 30 days after stroke, but the risk of death was similar in the two groups after one-month. Hypertension was the only cardiovascular disease risk factor associated with an increased mortality rate for hemorrhagic stroke as compared to ischemic stroke. © 2011 The Authors. International Journal of Stroke © 2011 World Stroke Organization.

Negotiating role management through everyday activities: narratives in action of two stroke survivors and their spouses.

PubMed

Satink, Ton; Josephsson, Staffan; Zajec, Jana; Cup, Edith H C; de Swart, Bert J M; Nijhuis-van der Sanden, Maria W G

2016-12-01

To manage social roles is a challenging part of self-management post-stroke. This study explored how stroke survivors act as role managers with their spouses in the context of everyday activities. Two stroke survivors with a first time stroke living at home with a spouse were included. Data were generated through participant observations at their own environment at 3, 6, 9, 15 and 21 months post-discharge. The narrative analysis focused on the actions of participants. Daily activities can be understood as an arena where role management and a meaningful live is negotiated and co-constructed with others. Everyday activities gave stroke survivors and their spouses insight into stroke survivors' capacities in daily situations. This was sometimes empowering, and other times conflicting when a spouse had negative perceptions of the abilities of the stroke survivors. The findings add to the current understanding of self-management and role management with regard to how these are situated in everyday activities. Daily activities can help both spouses to reflect and understand about self-management, role management and comanagement in daily life. Moreover, observing stroke survivors in everyday situations provides professionals with concrete pictures of stroke survivors' performance and self-management in interaction with their spouses. Implications for Rehabilitation Self-management is a dynamic process in which individuals actively manage a chronic condition and finally live a meaningful life with a long-term chronic condition; self-management can be divided into medical, role, and emotional management; comanagement is when individuals activate resources and use the capacities of other persons to manage a situation together. Self-management is situated in everyday activities. Everyday activities give stroke survivors ánd their partners impressions about stroke survivors' self-management abilities post-stroke in an everyday context. Everyday activities give stroke survivors ánd their partners an arena where role management and a meaningful life are negotiated and coconstructed through doing. Observing stroke survivors in everyday situations provides professionals a concreter picture of stroke survivors' self-management and comanagement with their partners than can be obtained from an informal interview.

Comparison of the Chinese ischemic stroke subclassification and Trial of Org 10172 in acute stroke treatment systems in minor stroke.

PubMed

Tan, Sha; Zhang, Lei; Chen, Xiaoyu; Wang, Yanqiang; Lin, Yinyao; Cai, Wei; Shan, Yilong; Qiu, Wei; Hu, Xueqiang; Lu, Zhengqi

2016-09-06

The underlying causes of minor stroke are difficult to assess. Here, we evaluate the reliability of the Chinese Ischemic Stroke Subclassification (CISS) system in patients with minor stroke, and compare it to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) system. A total of 320 patients with minor stroke were retrospectively registered and categorized into different subgroups of the CISS and TOAST by two neurologists. Inter- and intra-rater agreement with the two systems were assessed with kappa statistics. The percentage of undetermined etiology (UE) cases in the CISS system was 77.3 % less than that in the TOAST system, which was statistically significant (P < 0.001). The percentage of large artery atherosclerosis (LAA) in the CISS system was 79.7 % more than that in the TOAST system, which was also statistically significant (P < 0.001). The kappa values for inter-examiner agreement were 0.898 (P = 0.031) and 0.732 (P = 0.022) for the CISS and TOAST systems, respectively. The intra-observer reliability indexes were moderate (0.569 for neurologist A, and 0.487 for neurologist B). The CISS and TOAST systems are both reliable in classifying patients with minor stroke. CISS classified more patients into known etiologic categories without sacrificing reliability.

Uncooled Split-off Quantum Infrared Sensors for 3-5 Micron Imaging Applications

DTIC Science & Technology

2012-12-20

nonuniformity and needs to be optimized. Figure 5 (a) shows plots of Figure 3: (a) The responsivity and (b) detectivity variation with emitter...devices with larger mesa sizes than that with smaller sizes. The current nonuniformity originally results from the electric potential gradient in the...respectively. x = 0 represents the device center. The nonuniformity becomes remarkable when the temperature is increased. 5 2.3 Design of resonant

Laser-heated rocket thruster

NASA Technical Reports Server (NTRS)

Shoji, J. M.

1977-01-01

A space vehicle application using 5,000-kw input laser power was conceptually evaluated. A detailed design evaluation of a 10-kw experimental thruster including plasma size, chamber size, cooling, and performance analyses, was performed for 50 psia chamber pressure and using hydrogen as a propellant. The 10-kw hardware fabricated included a water cooled chamber, an uncooled copper chamber, an injector, igniters, and a thrust stand. A 10-kw optical train was designed.

Defense Industrial Base Assessment: U.S. Imaging and Sensors Industry

DTIC Science & Technology

2006-10-01

uncooled devices, but provide much higher resolution. The semiconductor material used in the detector is typically mercury cadmium telluride (HgCdTe...The material principally used in the arrays was mercury cadmium telluride (HgCdTe). Generation 2 detectors significantly improved the signal-to...Silicide (PtSi), Gallium Arsenide (GaAs), Aluminum Gallium Arsenide (AlGaAs), Mercury Cadmium Telluride (HgCdTe), Indium Gallium Arsenide (InGaAs

Next decade in infrared detectors

NASA Astrophysics Data System (ADS)

Rogalski, A.

2017-10-01

Fundamental and technological issues associated with the development and exploitation of the most advanced infrared technologies is discussed. In these classes of detectors both photon and thermal detectors are considered. Special attention is directed to HgCdTe ternary alloys, type II superlattices (T2SLs), barrier detectors, quantum wells, extrinsic detectors, and uncooled thermal bolometers. The sophisticated physics associated with the antimonide-based bandgap engineering will give a new impact and interest in development of infrared detector structures. Important advantage of T2SLs is the high quality, high uniformity and stable nature of the material. In general, III-V semiconductors are more robust than their II-VI counterparts due to stronger, less ionic chemical bonding. As a result, III-V-based FPAs excel in operability, spatial uniformity, temporal stability, scalability, producibility, and affordability - the so-called "ibility" advantages. In well established uncooled imaging, microbolometer arrays are clearly the most used technology. The microbolometer detectors are now produced in larger volumes than all other IR array technologies together. Present state-of-the-art microbolometers are based on polycrystalline or amorphous materials, typically vanadium oxide (VOx) or amorphous silicon (a-Si), with only modest temperature sensitivity and noise properties. Basic efforts today are mainly focused on pixel reduction and performance enhancement.

Metal silicide/poly-Si Schottky diodes for uncooled microbolometers

PubMed Central

2013-01-01

Nickel silicide Schottky diodes formed on polycrystalline Si 〈P〉 films are proposed as temperature sensors of monolithic uncooled microbolometer infrared focal plane arrays. The structure and composition of nickel silicide/polycrystalline silicon films synthesized in a low-temperature process are examined by means of transmission electron microscopy. The Ni silicide is identified as a multi-phase compound composed of 20% to 40% of Ni3Si, 30% to 60% of Ni2Si, and 10% to 30% of NiSi with probable minor content of NiSi2 at the silicide/poly-Si interface. Rectification ratios of the Schottky diodes vary from about 100 to about 20 for the temperature increasing from 22℃ to 70℃; they exceed 1,000 at 80 K. A barrier of around 0.95 eV is found to control the photovoltage spectra at room temperature. A set of barriers is observed in photo-electromotive force spectra at 80 K and attributed to the Ni silicide/poly-Si interface. Absolute values of temperature coefficients of voltage and current are found to vary from 0.3%℃ to 0.6%/℃ for forward bias and around 2.5%/℃ for reverse bias of the diodes. PMID:23594606

Radiative Properties of Thin Films of Common Dielectric Materials in the IR Spectral Range of 1.5-14.2 μm: Application to Infrared Imaging

NASA Astrophysics Data System (ADS)

Bañobre, Asahel; Marthi, Sita Rajyalaxmi; Ravindra, N. M.

2018-05-01

To measure, map and control temperature, imaging of materials in a thermal furnace routinely utilizes non-contact sensors, such as pyrometers. These pyrometers require a pre-knowledge of the radiative properties of materials in the desired infrared range of wavelengths. In this study, radiative properties of some commonly used thin films of dielectric materials are investigated within the infrared (IR) spectral range of 1.5-14.2 μm. Radiative properties of aluminum oxide (Al2O3), silicon dioxide (SiO2), aluminum nitride (AlN) and silicon nitride (Si3N4) have been simulated and compared, utilizing a matrix method of representing the optical properties. The simulated results of the radiative properties show that Si3N4 is an excellent choice for the infrared radiation absorbing layer that is currently used in infrared uncooled detectors (microbolometers) because of its optical, mechanical and electrical properties. A case study of the radiative properties of an infrared uncooled microbolometer (Honeywell structure) is presented and discussed in the infrared spectral range of 8-14 μm. The results obtained serve as useful information for the design and fabrication of infrared imaging systems and components such as coatings, detectors, filters, lenses and waveguides.

Optical response of laser-doped silicon carbide for an uncooled midwave infrared detector.

PubMed

Lim, Geunsik; Manzur, Tariq; Kar, Aravinda

2011-06-10

An uncooled mid-wave infrared (MWIR) detector is developed by doping an n-type 4H-SiC with Ga using a laser doping technique. 4H-SiC is one of the polytypes of crystalline silicon carbide and a wide bandgap semiconductor. The dopant creates an energy level of 0.30  eV, which was confirmed by optical spectroscopy of the doped sample. This energy level corresponds to the MWIR wavelength of 4.21  μm. The detection mechanism is based on the photoexcitation of electrons by the photons of this wavelength absorbed in the semiconductor. This process modifies the electron density, which changes the refractive index, and, therefore, the reflectance of the semiconductor is also changed. The change in the reflectance, which is the optical response of the detector, can be measured remotely with a laser beam, such as a He-Ne laser. This capability of measuring the detector response remotely makes it a wireless detector. The variation of refractive index was calculated as a function of absorbed irradiance based on the reflectance data for the as-received and doped samples. A distinct change was observed for the refractive index of the doped sample, indicating that the detector is suitable for applications at the 4.21  μm wavelength.

Uncooled Thermal Camera Calibration and Optimization of the Photogrammetry Process for UAV Applications in Agriculture

PubMed Central

Ballesteros, Rocío

2017-01-01

The acquisition, processing, and interpretation of thermal images from unmanned aerial vehicles (UAVs) is becoming a useful source of information for agronomic applications because of the higher temporal and spatial resolution of these products compared with those obtained from satellites. However, due to the low load capacity of the UAV they need to mount light, uncooled thermal cameras, where the microbolometer is not stabilized to a constant temperature. This makes the camera precision low for many applications. Additionally, the low contrast of the thermal images makes the photogrammetry process inaccurate, which result in large errors in the generation of orthoimages. In this research, we propose the use of new calibration algorithms, based on neural networks, which consider the sensor temperature and the digital response of the microbolometer as input data. In addition, we evaluate the use of the Wallis filter for improving the quality of the photogrammetry process using structure from motion software. With the proposed calibration algorithm, the measurement accuracy increased from 3.55 °C with the original camera configuration to 1.37 °C. The implementation of the Wallis filter increases the number of tie-point from 58,000 to 110,000 and decreases the total positing error from 7.1 m to 1.3 m. PMID:28946606

Uncooled Thermal Camera Calibration and Optimization of the Photogrammetry Process for UAV Applications in Agriculture.

PubMed

Ribeiro-Gomes, Krishna; Hernández-López, David; Ortega, José F; Ballesteros, Rocío; Poblete, Tomás; Moreno, Miguel A

2017-09-23

The acquisition, processing, and interpretation of thermal images from unmanned aerial vehicles (UAVs) is becoming a useful source of information for agronomic applications because of the higher temporal and spatial resolution of these products compared with those obtained from satellites. However, due to the low load capacity of the UAV they need to mount light, uncooled thermal cameras, where the microbolometer is not stabilized to a constant temperature. This makes the camera precision low for many applications. Additionally, the low contrast of the thermal images makes the photogrammetry process inaccurate, which result in large errors in the generation of orthoimages. In this research, we propose the use of new calibration algorithms, based on neural networks, which consider the sensor temperature and the digital response of the microbolometer as input data. In addition, we evaluate the use of the Wallis filter for improving the quality of the photogrammetry process using structure from motion software. With the proposed calibration algorithm, the measurement accuracy increased from 3.55 °C with the original camera configuration to 1.37 °C. The implementation of the Wallis filter increases the number of tie-point from 58,000 to 110,000 and decreases the total positing error from 7.1 m to 1.3 m.

Worldwide stroke incidence and early case fatality reported in 56 population-based studies: a systematic review.

PubMed

Feigin, Valery L; Lawes, Carlene M M; Bennett, Derrick A; Barker-Collo, Suzanne L; Parag, Varsha

2009-04-01

This systematic review of population-based studies of the incidence and early (21 days to 1 month) case fatality of stroke is based on studies published from 1970 to 2008. Stroke incidence (incident strokes only) and case fatality from 21 days to 1 month post-stroke were analysed by four decades of study, two country income groups (high-income countries and low to middle income countries, in accordance with the World Bank's country classification) and, when possible, by stroke pathological type: ischaemic stroke, primary intracerebral haemorrhage, and subarachnoid haemorrhage. This Review shows a divergent, statistically significant trend in stroke incidence rates over the past four decades, with a 42% decrease in stroke incidence in high-income countries and a greater than 100% increase in stroke incidence in low to middle income countries. In 2000-08, the overall stroke incidence rates in low to middle income countries have, for the first time, exceeded the level of stroke incidence seen in high-income countries, by 20%. The time to decide whether or not stroke is an issue that should be on the governmental agenda in low to middle income countries has now passed. Now is the time for action.

Relational Processing Following Stroke

ERIC Educational Resources Information Center

Andrews, Glenda; Halford, Graeme S.; Shum, David; Maujean, Annick; Chappell, Mark; Birney, Damian

2013-01-01

The research examined relational processing following stroke. Stroke patients (14 with frontal, 30 with non-frontal lesions) and 41 matched controls completed four relational processing tasks: sentence comprehension, Latin square matrix completion, modified Dimensional Change Card Sorting, and n-back. Each task included items at two or three…

Grip type and task goal modify reach-to-grasp performance in post-stroke hemiparesis

PubMed Central

Schaefer, Sydney Y.; DeJong, Stacey L.; Cherry, Kendra M.; Lang, Catherine E.

2011-01-01

This study investigated whether grip type and/or task goal influenced reaching and grasping performance in post-stroke hemiparesis. Sixteen adults with post-stroke hemiparesis and twelve healthy adults reached to and grasped a cylindrical object using one of two grip types (3-finger or palmar) to achieve one of two task goals (hold or lift). Performance of the stroke group was characteristic of hemiparetic limb movement during reach-to-grasp, with more curved handpaths and slower velocities compared to the control group. These effects were present regardless of grip type or task goal. Other measures of reaching (reach time and reach velocity at object contact) and grasping (peak thumb-index finger aperture during the reach and peak grip force during the grasp) were differentially affected by grip type, task goal, or both, despite the presence of hemiparesis, providing new evidence that changes in motor patterns after stroke may occur to compensate for stroke-related motor impairment. PMID:22357103

The Activation of the Mirror Neuron System during Action Observation and Action Execution with Mirror Visual Feedback in Stroke: A Systematic Review

PubMed Central

Zhang, Jack J. Q.; Welage, Nandana

2018-01-01

Objective To evaluate the concurrent and training effects of action observation (AO) and action execution with mirror visual feedback (MVF) on the activation of the mirror neuron system (MNS) and its relationship with the activation of the motor cortex in stroke individuals. Methods A literature search using CINAHL, PubMed, PsycINFO, Medline, Web of Science, and SCOPUS to find relevant studies was performed. Results A total of 19 articles were included. Two functional magnetic resonance imaging (fMRI) studies reported that MVF could activate the ipsilesional primary motor cortex as well as the MNS in stroke individuals, whereas two other fMRI studies found that the MNS was not activated by MVF in stroke individuals. Two clinical trials reported that long-term action execution with MVF induced a shift of activation toward the ipsilesional hemisphere. Five fMRI studies showed that AO activated the MNS, of which, three found the activation of movement-related areas. Five electroencephalography (EEG) studies demonstrated that AO or MVF enhanced mu suppression over the sensorimotor cortex. Conclusions MVF may contribute to stroke recovery by revising the interhemispheric imbalance caused by stroke due to the activation of the MNS. AO may also promote motor relearning in stroke individuals by activating the MNS and motor cortex. PMID:29853839

Exhaust emissions of low level blend alcohol fuels from two-stroke and four-stroke marine engines

NASA Astrophysics Data System (ADS)

Sevik, James M., Jr.

The U.S. Renewable Fuel Standard mandates that by 2022, 36 billion gallons of renewable fuels must be produced on a yearly basis. Ethanol production is capped at 15 billion gallons, meaning 21 billion gallons must come from different alternative fuel sources. A viable alternative to reach the remainder of this mandate is iso-butanol. Unlike ethanol, iso-butanol does not phase separate when mixed with water, meaning it can be transported using traditional pipeline methods. Iso-butanol also has a lower oxygen content by mass, meaning it can displace more petroleum while maintaining the same oxygen concentration in the fuel blend. This research focused on studying the effects of low level alcohol fuels on marine engine emissions to assess the possibility of using iso-butanol as a replacement for ethanol. Three marine engines were used in this study, representing a wide range of what is currently in service in the United States. Two four-stroke engine and one two-stroke engine powered boats were tested in the tributaries of the Chesapeake Bay, near Annapolis, Maryland over the course of two rounds of weeklong testing in May and September. The engines were tested using a standard test cycle and emissions were sampled using constant volume sampling techniques. Specific emissions for two-stroke and four-stroke engines were compared to the baseline indolene tests. Because of the nature of the field testing, limited engine parameters were recorded. Therefore, the engine parameters analyzed aside from emissions were the operating relative air-to-fuel ratio and engine speed. Emissions trends from the baseline test to each alcohol fuel for the four-stroke engines were consistent, when analyzing a single round of testing. The same trends were not consistent when comparing separate rounds because of uncontrolled weather conditions and because the four-stroke engines operate without fuel control feedback during full load conditions. Emissions trends from the baseline test to each alcohol fuel for the two-stroke engine were consistent for all rounds of testing. This is due to the fact the engine operates open-loop, and does not provide fueling compensation when fuel composition changes. Changes in emissions with respect to the baseline for iso-butanol were consistent with changes for ethanol. It was determined iso-butanol would make a viable replacement for ethanol.

Impact of the injection dose of exhaust gases, on work parameters of combustion engine

NASA Astrophysics Data System (ADS)

Marek, W.; Śliwiński, K.

2016-09-01

This article is another one from the series in which were presented research results indicated the possible areas of application of the pneumatic injection using hot combustion gases proposed by Professor Jarnuszkiewicz. This publication present the results of the control system of exhaust gas recirculation. The main aim of this research was to determine the effect of exhaust gas recirculation to the operating parameters of the internal combustion engine on the basis of laboratory measurements. All measurements were performed at a constant engine speed. These conditions correspond to the operation of the motor operating an electrical generator. The study was conducted on the four-stroke two-cylinder engine with spark ignition. The study were specifically tested on the air injection system and therefore the selection of the rotational speed was not bound, as in conventional versions of operating parameters of the electrical machine. During the measurement there were applied criterion which used power control corresponding to the requirements of load power, at minimal values of engine speed. Recirculation value determined by the following recurrent position control valve of the injection doses inflator gas for pneumatic injection system. They were studied and recorded, the impact of dose of gases recirculation to the operating and ecological engine parameters such as power, torque, specific fuel consumption, efficiency, air fuel ratio, exhaust gas temperature and nitrogen oxides and hydrocarbons.

Cardiorespiratory responses to orthostasis and the effects of propranolol

NASA Technical Reports Server (NTRS)

Loeppky, J. A.

1975-01-01

Cardiac output and gas exchange were determined serially using the single-breath method of Kim et al. before, during, and after orthostasis on six subjects after beta-adrenergic blockage and in duplicate controls. In the latter, heart rate increased and pulse pressure dropped immediately on tilting to 60 deg and remained stable while cardiac output and stroke volume declined gradually over 21 min upright. On propranolol, heart rate was 10 bpm lower supine and 20 bpm less at 60 deg but cardiac output was only slightly lower before and following tilt-up. However, after 15 min upright, stroke volume and cardiac output recovered on propranolol exceeding the controls after 21 min without change in heart rate. Returning to supine, heart rate dropped in all tests with a transitory increase in stroke volume, cardiac output and arteriovenous O2 difference. At the same time, apparent O2 uptake increased temporarily, reflecting the return of pooled venous blood to the lungs. Orthostatic tolerance did not appear to be affected by beta-adrenergic blockade.

[Descriptive study of cerebrovascular accidents in Douala, Cameroon].

PubMed

Chiasseu, Mbeumi M T; Mbahe, S

2011-10-01

A cerebrovascular accident or stroke is a sudden-onset cerebral deficit of vascular origin lasting more than 24 hours. These events represent the second leading cause of death in the world and take a particularly heavy toll in third world countries. The purpose of this study was to describe cerebrovascular lesions (type, location, size) as well as patient age and gender in Cameroon. Brain CT-scan and MRI findings from 50 stroke patients admitted to two health centers in Douala were reviewed. Data showed that 74% of patients were over 50 years of age, the 51-60 year group being the most affected. Patients were male in 64% of cases. Ischemic stroke accounted for 60% of cases versus 40% for hemorrhagic stroke. The most affected sites were the sylvian territory site in ischemic stroke and the temporal lobe in hemorrhagic stroke, acconting for 43.3% and 35% of cases respectively. The median size of ischemic and hemorrhagic lesions were 2.81 cm3, and 26.98 cm3 respectively. Hemorrhagic stroke and lacunar infarcts were more common in this sample. Discrepancies between results at the two hospitals may be due to the use of different imaging techniques. Indeed, MRI is known to be more sensitive than CT-scan for acute detection of stroke lesions.

Models for electromagnetic coupling of lightning onto multiconductor cables in underground cavities

NASA Astrophysics Data System (ADS)

Higgins, Matthew Benjamin

This dissertation documents the measurements, analytical modeling, and numerical modeling of electromagnetic transfer functions to quantify the ability of cloud-to-ground lightning strokes (including horizontal arc-channel components) to couple electromagnetic energy onto multiconductor cables in an underground cavity. Measurements were performed at the Sago coal mine located near Buckhannon, WV. These transfer functions, coupled with mathematical representations of lightning strokes, are then used to predict electric fields within the mine and induced voltages on a cable that was left abandoned in the sealed area of the Sago mine. If voltages reached high enough levels, electrical arcing could have occurred from the abandoned cable. Electrical arcing is known to be an effective ignition source for explosive gas mixtures. Two coupling mechanisms were measured: direct and indirect drive. Direct coupling results from the injection or induction of lightning current onto metallic conductors such as the conveyors, rails, trolley communications cable, and AC power shields that connect from the outside of the mine to locations deep within the mine. Indirect coupling results from electromagnetic field propagation through the earth as a result of a cloud-to-ground lightning stroke or a long, low-altitude horizontal current channel from a cloud-to-ground stroke. Unlike direct coupling, indirect coupling does not require metallic conductors in a continuous path from the surface to areas internal to the mine. Results from the indirect coupling measurements and analysis are of great concern. The field measurements, modeling, and analysis indicate that significant energy can be coupled directly into the sealed area of the mine. Due to the relatively low frequency content of lightning (< 100 kHz), electromagnetic energy can readily propagate through hundreds of feet of earth. Indirect transfer function measurements compare extremely well with analytical and computational models developed for the Sago site which take into account measured soil properties.

Evaluation of scavenging in two-stroke-cycle engines

NASA Technical Reports Server (NTRS)

Venediger, Herbert J

1934-01-01

The viewpoints are discussed, according to which the scavenging of two-stroke-cycle engines can be evaluated, and the relations between scavenging pressure and the quantity of the scavenging medium required, as also between the scavenging pressure and the revolution speed, are developed. It is further shown that the power increase is limited by the scavenging process, so that further researches are desirable for qualitative improvement. These results lead to several conclusions regarding the propulsion of motor vehicles by the two-stroke-cycle engines. Lastly, attention is called to the fundamental defect of the two-dimensional treatment of the scavenging process and to the consequent distinction between the two-dimensional and three-dimensional scavenging-type efficiency.

Recent Development of the Two-Stroke Engine. 2 - Design Features

DTIC Science & Technology

1945-05-01

NATIONALADVISORYCOMMI~EE FOR AERONAUTICS. TECHNICAL MEMORANDUM No, 1082 R~CENT DEVELOPMENT OX’ THE TWO–STROKE ENGTNE II - DES IGN l’llATURliS By J...MEMORANDUM . ... . ,., . ,.!. .,, .,- ... —--— — FOR AERONAUTICS ‘ NO. 1082 , > ,. RECENT DEVELOPMENT OF THE TWO-STROKE ENGINE II - DESIGN FEATURES* ,“” By...lUOTE: Reprint of R.T.P.3 Translation No. 2382; issued by the Ministry of Aircraft Production, London, England. II: ._: 2 NACA TM NO. 1082 (=“) The

[The prevalence and status of pre-hospital treatments of risk factors among patients with stroke in China].

PubMed

Tang, Meilian; Sun, Jiayi; Wang, Wei; Liu, Jing; Chao, Baohua; Liu, Jun; Cao, Lei; Qi, Yue; Wang, Ying; Zhao, Dong

2015-12-01

To analyze the distribution and treatment of risk factors in hospitalized stroke patients before stroke onset. This was a multi-center cross-sectional study. Patients with acute stroke were collected from 41 hospitals in 25 provinces in China from January to May in 2011. A total of 20 570 stoke patients (13 062 men, 7 508 women) aged (63.0 ± 12.9) years were enrolled and analyzed in this study. Among them, 15 329 were first-onset stroke, and 17 052 were ischemic stroke. (1) Of all the subjects, 75.5% were with hypertension, 53.5% with elevated LDL-C, 37.3% with diabetes, and 6.5% with atrial fibrillation. 75.2% of them had two or more above risk factors and 43.0% had three or more risk factors. (2) According to the current definition, 53.3% of the first-onset stroke patients were classified as at high risk and 25.9% were classified as at low risk. Noticeably, 42.1% of the patients below 65 years old were at low risk by the same definition. (3) The awareness rate of hypertension was 70.3% in the first-onset stroke patients. However, only 20.1% of the patients reached the target of blood pressure control in the treatment. Although the awareness rate of hypertension and diabetes among recurrent stroke patients were relatively high, the treatment and control rates of these risk factors were still low. Compared with the other two risk factors, the awareness, treatment and control rates of elevated LDL-C were much lower. Majority of the stroke patients are complicated with multiple risk factors before stroke onset, suggesting a great needs for improving the primary and secondary prevention of stroke in China. In addition, the definition for risk classification of stroke may need to be modified for subjects under 65 years old.

Problematising risk in stroke rehabilitation.

PubMed

Egan, Mary Y; Kessler, Dorothy; Ceci, Christine; Laliberté-Rudman, Debbie; McGrath, Colleen; Sikora, Lindsey; Gardner, Paula

2016-11-01

Following stroke, re-engagement in personally valued activities requires some experience of risk. Risk, therefore, must be seen as having positive as well as negative aspects in rehabilitation. Our aim was to identify the dominant understanding of risk in stroke rehabilitation and the assumptions underpinning these understandings, determine how these understandings affect research and practise, and if necessary, propose alternate ways to conceptualise risk in research and practise. Alvesson and Sandberg's method of problematisation was used. We began with a historical overview of stroke rehabilitation, and proceeded through five steps undertaken in an iterative fashion: literature search and selection; data extraction; syntheses across texts; identification of assumptions informing the literature and; generation of alternatives. Discussion of risk in stroke rehabilitation is largely implicit. However, two prominent conceptualisations of risk underpin both knowledge development and clinical practise: the risk to the individual stroke survivor of remaining dependent in activities of daily living and the risk that the health care system will be overwhelmed by the costs of providing stroke rehabilitation. Conceptualisation of risk in stroke rehabilitation, while implicit, drives both research and practise in ways that reinforce a focus on impairment and a generic, decontextualised approach to rehabilitation. Implications for rehabilitation Much of stroke rehabilitation practise and research seems to centre implicitly on two risks: risk to the patient of remaining dependent in ADL and risk to the health care system of bankruptcy due to the provision of stroke rehabilitation. The implicit focus on ADL dependence limits the ability of clinicians and researchers to address other goals supportive of a good life following stroke. The implicit focus on financial risk to the health care system may limit access to rehabilitation for people who have experienced either milder or more severe stroke. Viewing individuals affected by stroke as possessing a range of independence and diverse personally valued activities that exist within a network of relations offers wider possibilities for action in rehabilitation.

Night vision in Thales Angenieux: custom solutions for hand-held devices

NASA Astrophysics Data System (ADS)

Rollin, Joel; Teszner, Jean Louis

2005-01-01

Thales Anenieux has been manufacturing for two decades flexible light intensifier goggles that have been popular over numerous countries: thanks to the advent of uncooled microbolometer arrays, further outlooks are settled. Army Forces can have now at their command a multi-purpose and cost effective set of devices that answer most of the battlefield mission profiles. Thales Angenieux move from light intensifier goggles to low cost infared imagers and this smooth change is sketched out: our erlier experience on compact and user-friendly L.I equipment, especially in the field of the opto-mechanical design, has helped us to push forward the best compromises. Our product line policy is displayed: really, we have made a point of addressing many potential customers demands by singling out a modular approach. Further developments are now going on.

Perinatal ischemic stroke: a five-year retrospective study in a level-III maternity

PubMed Central

Machado, Virgínia; Pimentel, Sónia; Pinto, Filomena; Nona, José

2015-01-01

Objective To study the incidence, clinical presentation, risk factors, imaging diagnosis, and clinical outcome of perinatal stroke. Methods Data was retrospectively collected from full-term newborns admitted to the neonatal unit of a level III maternity in Lisbon with cerebral stroke, from January 2007 to December 2011. Results There were 11 cases of stroke: nine were arterial ischemic stroke and two were cerebral venous sinus thrombosis. We estimated an incidence of arterial ischemic stroke of 1.6/5,000 births and of cerebral venous sinus thrombosis of 7.2/100,000 births. There were two cases of recurrent stroke. Eight patients presented with symptoms while the remaining three were asymptomatic and incidentally diagnosed. The most frequently registered symptoms (8/11) were seizures; in that, generalized clonic (3/8) and focal clonic (5/8). Strokes were more commonly left-sided (9/11), and the most affected artery was the left middle cerebral artery (8/11). Transfontanelle ultrasound was positive in most of the patients (10/11), and stroke was confirmed by cerebral magnetic resonance in all patients. Electroencephalographic recordings were carried out in five patients and were abnormal in three (focal abnormalities n=2, burst-suppression pattern n=1). Eight patients had previously identified risk factors for neonatal stroke which included obstetric and neonatal causes. Ten patients were followed up at outpatients setting; four patients developed motor deficits and one presented with epilepsy. Conclusions Although a modest and heterogeneous sample, this study emphasizes the need for a high level of suspicion when it comes to neonatal stroke, primarily in the presence of risk factors. The prevalence of neurological sequelae in our series supports the need of long-term follow-up and early intervention strategies. PMID:25993071

Recovering from a stroke: a longitudinal, qualitative study of older Norwegian women.

PubMed

Eilertsen, Grethe; Kirkevold, Marit; Bjørk, Ida Torunn

2010-07-01

To illuminate older women's experiences and the characteristics of the recovery process following a stroke. Patients with stroke face serious challenges related to bodily changes, existential aspects and daily life after stroke. Few qualitative longitudinal studies have examined the recovery process from the perspective of the patient. Knowledge about older women's experiences in coping with life after a stroke is limited. Prospective, longitudinal, case-study design. Six women aged 68-83 suffering from first-time stroke were recruited from two stroke units. Each participant was interviewed in-depth 12-14 times during the first two years post stroke. The interviews addressed how they experienced their body, their self-understanding, daily life and how this had changed over time. Most interviews took place in the participants' homes. Gadamer's philosophical hermeneutics informed the analyses. Post stroke recovery was slow and complex and evolved through four distinct phases. In the first phase (0-2 months post stroke), the participants' main concerns were their bodily changes; in the second phase (2-6 months), activities of daily life; in the third phase (6-12 months), self-understanding and in the fourth phase (12-24 months), going on with life. The transition between phases was gradual. Recovery from stroke evolves over time through four distinct phases, which differ depending on significant experiences and associated meanings. Psychological and social resources are equally critical in the women's process of recovery. The four phases of rehabilitation suggest at what points various concerns require increased therapeutic attention. Psychological and social resources must be vitalised at an early phase similar to bodily resources. This knowledge may assist professionals in offering adequate help throughout the recovery process even beyond the established rehabilitation period. © 2010 Blackwell Publishing Ltd.

Two-color detector: Mercury-cadmium-telluride as a terahertz and infrared detector

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

Sizov, F.; Zabudsky, V.; Petryakov, V.

2015-02-23

In this paper, issues associated with the development of infrared (IR) and terahertz (THz) radiation detectors based on HgCdTe are discussed. Two-color un-cooled and cooled to 78 K narrow-gap mercury-cadmium-telluride semiconductor thin layers with antennas were considered both as sub-THz (sub-THz) direct detection bolometers and 3–10 μm IR photoconductors. The noise equivalent power (NEP) for one of the detectors studied at ν ≈ 140 GHz reaches NEP{sub 300 K} ≈ 4.5 × 10{sup −10} W/Hz{sup 1/2} and NEP{sub 78 K} ≈ 5 × 10{sup −9} W/Hz{sup 1/2}. The same detector used as an IR photoconductor showed the responsivity at temperatures T = 78 K and 300 K with signal-to-noisemore » ratio S/N ≈ 750 and 50, respectively, under illumination by using IR monochromator and globar as a thermal source.« less

Predictors of long-term survival among first-ever ischemic and hemorrhagic stroke in a Brazilian stroke cohort.

PubMed

Goulart, Alessandra C; Fernandes, Tiotrefis G; Santos, Itamar S; Alencar, Airlane P; Bensenor, Isabela M; Lotufo, Paulo A

2013-05-24

Few studies have examined both ischemic and hemorrhagic stroke to identify prognostic factors associated to long-term stroke survival. We investigated long-term survival and predictors that could adversely influence ischemic and hemorrhagic first-ever stroke prognosis. We prospectively ascertained 665 consecutive first-ever ischemic and hemorrhagic stroke cases from "The Study of Stroke Mortality and Morbidity" (The EMMA Study) in a community hospital in São Paulo, Brazil. We evaluated cardiovascular risk factors and sociodemographic characteristics (age, gender, race and educational level). We found a lower survival rate among hemorrhagic cases compared to ischemic stroke cases at the end of 4 years of follow-up (52% vs. 44%, p = 0.04). The risk of death was two times higher among people with ischemic stroke without formal education. Also, we found consistently higher risk of death for diabetics with ischemic stroke (HR = 1.45; 95% CI = 1.07-1.97) compared to no diabetics. As expected, age equally influenced on the high risk of poor survival, regardless of stroke subtype. For ischemic stroke, the lack of formal education and diabetes were significant independent predictors of poor long-term survival.

Return stroke velocities and currents using a solid state silicon detector system

NASA Technical Reports Server (NTRS)

Mach, Douglas M.; Rust, W. David

1988-01-01

A small, portable device has been developed to measure return stroke velocities. With the device, velocities from 135 strokes that consist of 92 natural return strokes and 43 triggered return strokes have been analyzed. The average return stroke velocity for longer channels, greater than 500 meters, is 1.2 + or - 0.3 x 10 to the 8th m/s for both natural and triggered return strokes. For shorter channel lengths, less than 500 m, natural lightning has a statistically higher average return stroke velocity of 1.9 + or - 0.7 x 10 to the 8th m/s than triggered lightning with an average return stroke velocity of 1.4 + or - 0.4 x 10 to the 8th m/s. Using the transmission line model of the return stroke, natural lightning has a peak current distribution that is log-normal with a median value of 19 kA. Return stroke velocities and currents were determined for two distant single stroke natural positive cloud-to-ground flashes. The velocities were 1.0 and 1.7 x 10 to the 8th ms/s while the estimated peak current for each positive flash was over 125 kA.

Goal-directed fluid optimization based on stroke volume variation and cardiac index during one-lung ventilation in patients undergoing thoracoscopy lobectomy operations: a pilot study.

PubMed

Zhang, Jian; Chen, Chao Qin; Lei, Xiu Zhen; Feng, Zhi Ying; Zhu, Sheng Mei

2013-07-01

This pilot study was designed to utilize stroke volume variation and cardiac index to ensure fluid optimization during one-lung ventilation in patients undergoing thoracoscopic lobectomies. Eighty patients undergoing thoracoscopic lobectomy were randomized into either a goal-directed therapy group or a control group. In the goal-directed therapy group, the stroke volume variation was controlled at 10%±1%, and the cardiac index was controlled at a minimum of 2.5 L.min-1.m-2. In the control group, the MAP was maintained at between 65 mm Hg and 90 mm Hg, heart rate was maintained at between 60 BPM and 100 BPM, and urinary output was greater than 0.5 mL/kg-1/h-1. The hemodynamic variables, arterial blood gas analyses, total administered fluid volume and side effects were recorded. The PaO2/FiO2-ratio before the end of one-lung ventilation in the goal-directed therapy group was significantly higher than that of the control group, but there were no differences between the goal-directed therapy group and the control group for the PaO2/FiO2-ratio or other arterial blood gas analysis indices prior to anesthesia. The extubation time was significantly earlier in the goal-directed therapy group, but there was no difference in the length of hospital stay. Patients in the control group had greater urine volumes, and they were given greater colloid and overall fluid volumes. Nausea and vomiting were significantly reduced in the goal-directed therapy group. The results of this study demonstrated that an optimization protocol, based on stroke volume variation and cardiac index obtained with a FloTrac/Vigileo device, increased the PaO2/FiO2-ratio and reduced the overall fluid volume, intubation time and postoperative complications (nausea and vomiting) in thoracic surgery patients requiring one-lung ventilation.

Characterization of fluid physics effects on cardiovascular response to microgravity (G-572)

NASA Technical Reports Server (NTRS)

Pantalos, George M.; Sharp, M. Keith; Woodruff, Stewart J.; Lorange, Richard D.; Bennett, Thomas E.; Sojka, Jan J.; Lemon, Mark W.

1993-01-01

The recognition and understanding of cardiovascular adaptation to spaceflight has experienced substantial advancement in the last several years. In-flight echocardiographic measurements of astronaut cardiac function on the Space Shuttle have documented a 15 percent reduction in both left ventricular volume index and stroke volume with a compensatory increase in heart rate to maintain cardiac output. To date, the reduced cardiac size and stroke volume have been presumed to be the consequence of the reduction in circulating fluid volume following diuresis and other physiological processes to reduce blood volume within a few days after orbital insertion. However, no specific mechanism for the reduced stroke volume has been elucidated. The following investigation proposes the use of a hydraulic model of the cardiovascular system to examine the possibility that the observed reduction in stroke volume may, in part, be related to fluid physics effects on heart function. The automated model is being prepared to fly as a GAS payload. The experimental apparatus consists of a pneumatically actuated, elliptical artificial ventricle connected to a closed-loop, hydraulic circuit with compliance and resistance elements to create physiologic pressure and flow conditions. The ventricle is instrumented with high-fidelity, acceleration-insensitive, catheter-tip pressure transducers (Millar Instruments) in the apex and base to determine the instantaneous ventricular pressures and (delta)P(sub LV) across the left ventricle (LVP(sub apex)-LVP(sub base). The ventricle is also instrumented with a flow probe and pressure transducers immediately upstream of the inflow valve and downstream of the outflow valve. The experiment will be microprocessor controlled with analog signals stored on the FM data tape recorder. By varying the circulating fluid volume, ventricular function can be determined for varying preload pressures with fixed afterload pressure. Pilot experiments on board the NASA KC-135 aircraft have demonstrated proof-of-concept and provided early support for the proposed hypothesis. A review of the pilot experiments and developmental progress on the GAS version of this experiment will be presented.

Effects of aspirin plus extended-release dipyridamole versus clopidogrel and telmisartan on disability and cognitive function after recurrent stroke in patients with ischaemic stroke in the Prevention Regimen for Effectively Avoiding Second Strokes (PRoFESS) trial: a double-blind, active and placebo-controlled study.

PubMed

Diener, Hans-Christoph; Sacco, Ralph L; Yusuf, Salim; Cotton, Daniel; Ounpuu, Stephanie; Lawton, William A; Palesch, Yuko; Martin, Reneé H; Albers, Gregory W; Bath, Philip; Bornstein, Natan; Chan, Bernard P L; Chen, Sien-Tsong; Cunha, Luis; Dahlöf, Björn; De Keyser, Jacques; Donnan, Geoffrey A; Estol, Conrado; Gorelick, Philip; Gu, Vivian; Hermansson, Karin; Hilbrich, Lutz; Kaste, Markku; Lu, Chuanzhen; Machnig, Thomas; Pais, Prem; Roberts, Robin; Skvortsova, Veronika; Teal, Philip; Toni, Danilo; VanderMaelen, Cam; Voigt, Thor; Weber, Michael; Yoon, Byung-Woo

2008-10-01

The treatment of ischaemic stroke with neuroprotective drugs has been unsuccessful, and whether these compounds can be used to reduce disability after recurrent stroke is unknown. The putative neuroprotective effects of antiplatelet compounds and the angiotensin II receptor antagonist telmisartan were investigated in the Prevention Regimen for Effectively Avoiding Second Strokes (PRoFESS) trial. Patients who had had an ischaemic stroke were randomly assigned in a two by two factorial design to receive either 25 mg aspirin (ASA) and 200 mg extended-release dipyridamole (ER-DP) twice a day or 75 mg clopidogrel once a day, and either 80 mg telmisartan or placebo once per day. The predefined endpoints for this substudy were disability after a recurrent stroke, assessed with the modified Rankin scale (mRS) and Barthel index at 3 months, and cognitive function, assessed with the mini-mental state examination (MMSE) score at 4 weeks after randomisation and at the penultimate visit. Analysis was by intention to treat. The study was registered with ClinicalTrials.gov, number NCT00153062. 20,332 patients (mean age 66 years) were randomised and followed-up for a median of 2.4 years. Recurrent strokes occurred in 916 (9%) patients randomly assigned to ASA with ER-DP and 898 (9%) patients randomly assigned to clopidogrel; 880 (9%) patients randomly assigned to telmisartan and 934 (9%) patients given placebo had recurrent strokes. mRS scores were not statistically different in patients with recurrent stroke who were treated with ASA and ER-DP versus clopidogrel (p=0.38), or with telmisartan versus placebo (p=0.61). There was no significant difference in the proportion of patients with recurrent stroke with a good outcome, as measured with the Barthel index, across all treatment groups. Additionally, there was no significant difference in the median MMSE scores, the percentage of patients with an MMSE score of 24 points or less, the percentage of patients with a drop in MMSE score of 3 points or more between 1 month and the penultimate visit, and the number of patients with dementia among the treatment groups. There were no significant differences in the proportion of patients with cognitive impairment or dementia among the treatment groups. Disability due to recurrent stroke and cognitive decline in patients with ischaemic stroke were not different between the two antiplatelet regimens and were not affected by the preventive use of telmisartan.

Assessing the Cognitive Regulation of Emotion in Depressed Stroke Patients

ERIC Educational Resources Information Center

Turner, Margaret A.; Andrewes, David G.

2010-01-01

This study evaluated the psychometric properties of a simple scale for measuring positive interpersonal attitudes of depressed stroke patients, with regard to their cognitive limitations. Two versions of the Attitudes Towards Relationships Scale were developed and administered to depressed stroke (n = 48) and control rheumatic/orthopaedic (n = 45)…

Cervical Epidural Abscess Mimicking as Stroke - Report of Two Cases

PubMed Central

Velpula, Jagan Mohana Reddy; Gakhar, Harinder; Sigamoney, Kohilavani; Bommireddy, Rajendra

2014-01-01

Background: Stroke is a common provisional diagnosis in patients presenting to the emergency department (ED) with unilateral neurological deficit. Cervical epidural abscess (CEA) may also present clinically with a unilateral neurological deficit. Objects: To highlight the inherent problems with diagnosing cervical epidural abscess and possible consequences of delay in diagnosis. Case Report: We would like to highlight two cases provisionally diagnosed as stroke. Both cases turned out to be cervical epidural abscesses. The delay in diagnosis and treatment led to suboptimal outcome in both cases. Summary: Cases with suspected stroke who deteriorate while under treatment or whose diagnosis is doubtful should have MRI whole spine in order to avoid potential complications. PMID:24551026

Insight of Human Stroke from blood flow and blood pressure

NASA Astrophysics Data System (ADS)

Chen, Zhi; Ivanov, Plamen Ch.; Hu, Kun; Stanley, H. Eugene

2003-03-01

Stroke is is one of the leading cause of death and disability in the world. It is well believed that stroke is caused by the disturbance of cerebrovascular autoregulation. We investigate the blood flow on the left and right middle cerebral artery and beat-to-beat blood pressure simultaneously measured from the finger, for both subjects with stroke and healthy subjects. Synchronization technique is used to distinguish the difference between these two groups.

Sexual dimorphism in ischemic stroke: lessons from the laboratory

PubMed Central

Manwani, Bharti; McCullough, Louise D

2011-01-01

Ischemic stroke is emerging as a major health problem for elderly women. Women have lower stroke incidence than men until an advanced age, when the epidemiology of ischemic stroke shifts and incidence rises dramatically in women. Experimental models of rodent stroke have replicated this clinical epidemiology, with exacerbated injury in older compared with young female rodents Many of the detrimental effects of aging on ischemic stroke outcome in females can be replicated by ovariectomy, suggesting that hormones such as estrogen play a neuroprotective role. However, emerging data suggest that the molecular mechanisms leading to ischemic cell death differ in the two sexes, and these effects may be independent of circulating hormone levels. This article highlights recent clinical and experimental literature on sex differences in stroke outcomes and mechanisms. PMID:21612353

[Stroke and Cancer: Are Cryptogenic Strokes a Paraneoplastic Syndrome?].

PubMed

Eschle, Daniel

2015-07-22

Cancer is an independent risk factor for ischemic stroke, and stroke can precede tumour diagnosis by many months. A paraneoplastic hypercoagulability has been implicated. Overall, cancer is a rare cause, but should be suspected in cases of cryptogenic stroke. In patients with cryptogenic stroke, two criteria – ischemic lesions in multiple vascular territories and D-dimer values >2,15 µg/ml – predict cancer with 100% specificity according to one relevant study. An adenocarcinoma at an advanced stage is identified in many cases, the risk of stroke-recurrence is high. There is a lack of evidence-based recommendations regarding secondary prevention in these cases. In analogy to the guidelines for venous thromboembolism in cancer patients, low molecular weight heparins might be more efficient compared to other anti-clotting agents.

Cognitive rehabilitation for memory deficits following stroke.

PubMed

Majid, M J; Lincoln, N B; Weyman, N

2000-01-01

Memory problems occur following stroke. Cognitive rehabilitation programmes are provided to retrain memory function or to teach patients strategies to cope despite memory impairment. To determine the effects of cognitive rehabilitation for memory problems following stroke. We searched the Cochrane Stroke Group Trials Register, Medline, EMBASE, CINHAL and CLIN PSYCH databases and reference lists from relevant articles. Date of most recent searches: December 1998. Controlled trials of memory retraining in stroke. Studies with mixed aetiology groups were excluded unless they had more than 75% of stroke patients or separate data were available for the stroke patients. Two reviewers extracted trial data and assessed trial quality. Reviewers contacted investigators for further details of trials. One trial was identified with 12 participants. This showed memory strategy training had no significant effect on memory impairment or subjective memory complaints. There is insufficient evidence to support or refute the effectiveness of cognitive rehabilitation for memory problems after stroke.

Wavelength- or Polarization-Selective Thermal Infrared Detectors for Multi-Color or Polarimetric Imaging Using Plasmonics and Metamaterials

PubMed Central

Ogawa, Shinpei; Kimata, Masafumi

2017-01-01

Wavelength- or polarization-selective thermal infrared (IR) detectors are promising for various novel applications such as fire detection, gas analysis, multi-color imaging, multi-channel detectors, recognition of artificial objects in a natural environment, and facial recognition. However, these functions require additional filters or polarizers, which leads to high cost and technical difficulties related to integration of many different pixels in an array format. Plasmonic metamaterial absorbers (PMAs) can impart wavelength or polarization selectivity to conventional thermal IR detectors simply by controlling the surface geometry of the absorbers to produce surface plasmon resonances at designed wavelengths or polarizations. This enables integration of many different pixels in an array format without any filters or polarizers. We review our recent advances in wavelength- and polarization-selective thermal IR sensors using PMAs for multi-color or polarimetric imaging. The absorption mechanism defined by the surface structures is discussed for three types of PMAs—periodic crystals, metal-insulator-metal and mushroom-type PMAs—to demonstrate appropriate applications. Our wavelength- or polarization-selective uncooled IR sensors using various PMAs and multi-color image sensors are then described. Finally, high-performance mushroom-type PMAs are investigated. These advanced functional thermal IR detectors with wavelength or polarization selectivity will provide great benefits for a wide range of applications. PMID:28772855

Wavelength- or Polarization-Selective Thermal Infrared Detectors for Multi-Color or Polarimetric Imaging Using Plasmonics and Metamaterials.

PubMed

Ogawa, Shinpei; Kimata, Masafumi

2017-05-04

Wavelength- or polarization-selective thermal infrared (IR) detectors are promising for various novel applications such as fire detection, gas analysis, multi-color imaging, multi-channel detectors, recognition of artificial objects in a natural environment, and facial recognition. However, these functions require additional filters or polarizers, which leads to high cost and technical difficulties related to integration of many different pixels in an array format. Plasmonic metamaterial absorbers (PMAs) can impart wavelength or polarization selectivity to conventional thermal IR detectors simply by controlling the surface geometry of the absorbers to produce surface plasmon resonances at designed wavelengths or polarizations. This enables integration of many different pixels in an array format without any filters or polarizers. We review our recent advances in wavelength- and polarization-selective thermal IR sensors using PMAs for multi-color or polarimetric imaging. The absorption mechanism defined by the surface structures is discussed for three types of PMAs-periodic crystals, metal-insulator-metal and mushroom-type PMAs-to demonstrate appropriate applications. Our wavelength- or polarization-selective uncooled IR sensors using various PMAs and multi-color image sensors are then described. Finally, high-performance mushroom-type PMAs are investigated. These advanced functional thermal IR detectors with wavelength or polarization selectivity will provide great benefits for a wide range of applications.

Effects of wake and shock passing on the heat transfer to a film cooled transonic turbine blade

NASA Astrophysics Data System (ADS)

Rigby, M. J.

An attempt is made to further the understanding of film cooling process in an engine environment. The environment in a gas turbine is unsteady. A source of unsteadiness, the cutting of nozzle guide vane (NGV) wakes and shock waves by the rotor, was modeled experimentally. The influence of the unsteady wakes and shock waves on the heat transfer to a film cooled rotor blade was studied for five film cooling configurations using a rotating bar apparatus in front of a 2-D cascade. Heat transfer measurements were made using thin film gauges placed at the mid-span of the test blade. Schlieren photography was used to study the behavior of the coolant film and the movement of the unsteady shock waves and wakes. The effect of simulated NGV wake passing observed on the uncooled airfoil is to promote an intermittent transition of the suction surface. The effect of the wake on the turbulent pressure surface is small. With injection on the suction surface, the film acts as a boundary layer trip which offsets the rise in heat transfer due to the wake. The simulated NGV trailing edge shock wave had a dramatic effect on the suction surface heat transfer.

Overview of diagnostic performance and results for the first operation phase in Wendelstein 7-X (invited).

PubMed

Krychowiak, M; Adnan, A; Alonso, A; Andreeva, T; Baldzuhn, J; Barbui, T; Beurskens, M; Biel, W; Biedermann, C; Blackwell, B D; Bosch, H S; Bozhenkov, S; Brakel, R; Bräuer, T; Brotas de Carvalho, B; Burhenn, R; Buttenschön, B; Cappa, A; Cseh, G; Czarnecka, A; Dinklage, A; Drews, P; Dzikowicka, A; Effenberg, F; Endler, M; Erckmann, V; Estrada, T; Ford, O; Fornal, T; Frerichs, H; Fuchert, G; Geiger, J; Grulke, O; Harris, J H; Hartfuß, H J; Hartmann, D; Hathiramani, D; Hirsch, M; Höfel, U; Jabłoński, S; Jakubowski, M W; Kaczmarczyk, J; Klinger, T; Klose, S; Knauer, J; Kocsis, G; König, R; Kornejew, P; Krämer-Flecken, A; Krawczyk, N; Kremeyer, T; Książek, I; Kubkowska, M; Langenberg, A; Laqua, H P; Laux, M; Lazerson, S; Liang, Y; Liu, S C; Lorenz, A; Marchuk, A O; Marsen, S; Moncada, V; Naujoks, D; Neilson, H; Neubauer, O; Neuner, U; Niemann, H; Oosterbeek, J W; Otte, M; Pablant, N; Pasch, E; Sunn Pedersen, T; Pisano, F; Rahbarnia, K; Ryć, L; Schmitz, O; Schmuck, S; Schneider, W; Schröder, T; Schuhmacher, H; Schweer, B; Standley, B; Stange, T; Stephey, L; Svensson, J; Szabolics, T; Szepesi, T; Thomsen, H; Travere, J-M; Trimino Mora, H; Tsuchiya, H; Weir, G M; Wenzel, U; Werner, A; Wiegel, B; Windisch, T; Wolf, R; Wurden, G A; Zhang, D; Zimbal, A; Zoletnik, S

2016-11-01

Wendelstein 7-X, a superconducting optimized stellarator built in Greifswald/Germany, started its first plasmas with the last closed flux surface (LCFS) defined by 5 uncooled graphite limiters in December 2015. At the end of the 10 weeks long experimental campaign (OP1.1) more than 20 independent diagnostic systems were in operation, allowing detailed studies of many interesting plasma phenomena. For example, fast neutral gas manometers supported by video cameras (including one fast-frame camera with frame rates of tens of kHz) as well as visible cameras with different interference filters, with field of views covering all ten half-modules of the stellarator, discovered a MARFE-like radiation zone on the inboard side of machine module 4. This structure is presumably triggered by an inadvertent plasma-wall interaction in module 4 resulting in a high impurity influx that terminates some discharges by radiation cooling. The main plasma parameters achieved in OP1.1 exceeded predicted values in discharges of a length reaching 6 s. Although OP1.1 is characterized by short pulses, many of the diagnostics are already designed for quasi-steady state operation of 30 min discharges heated at 10 MW of ECRH. An overview of diagnostic performance for OP1.1 is given, including some highlights from the physics campaigns.

Oxide-dispersion-strengthened turbine blades, volume 1. [MA6000 alloy

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

Millan, P.P. Jr.; Mays, J.C.

1986-10-01

The objective of Project 4 was to develop a high-temperature, uncooled gas turbine blade using MA6000 alloy. The program objectives were achieved. Production scale up of the MA6000 alloy was achieved with a fair degree of tolerance to nonoptimum processing. The blade manufacturing process was also optimized. The mechanical, environmental, and physical property evaluations of MA6000 were conducted. The ultimate tensile strength, to about 704 C (130 F), is higher than DS MAR-M 247 but with a corresponding lower tensile elongation. Also, above 982 C (180 F) MA6000 tensile strength does not decrease as rapidly as MAR-M 247 because themore » ODS mechanism still remains active. Based on oxidation resistance and diffusional stability considerations, NiCrAlY coatings are recommended. CoCrAly coating should be applied on top of a thin NiCrAlY coating. Vibration tests, whirlpit tests, and a high-rotor-rig test were conducted to ensure successful completion of the engine test of the MA6000 TFE731 high pressure turbine blades. The results of these tests were acceptable. In production quantities, the cost of the Project 4 MA6000 blade is estimated to be about twice that of a cast DS MAR-M 247 blade.« less

Stroke doctors: Who are we? A World Stroke Organization survey.

PubMed

Meretoja, Atte; Acciarresi, Monica; Akinyemi, Rufus O; Campbell, Bruce; Dowlatshahi, Dar; English, Coralie; Henninger, Nils; Poppe, Alexandre; Putaala, Jukka; Saini, Monica; Sato, Shoichiro; Wu, Bo; Brainin, Michael; Norrving, Bo; Davis, Stephen

2017-10-01

Background Specialist training provides skilled workforce for service delivery. Stroke medicine has evolved rapidly in the past years. No prior information exists on background or training of stroke doctors globally. Aims To describe the specialties that represent stroke doctors, their training requirements, and the scientific organizations ensuring continuous medical education. Methods The World Stroke Organization conducted an expert survey between June and November 2014 using e-mailed questionnaires. All Organization for Economic Co-operation and Development countries with >1 million population and other countries with >50 million population were included ( n = 49, total 5.6 billion inhabitants, 85% of global strokes). Two stroke experts from each selected country were surveyed, discrepancies resolved, and further information on identified stroke-specific curricula sought. Results We received responses from 48 (98%) countries. Of ischemic stroke patients, 64% were reportedly treated by neurologists, ranging from 5% in Ireland to 95% in the Netherlands. Per thousand annual strokes there were average six neurologists, ranging from 0.3 in Ethiopia to 33 in Israel. Of intracerebral hemorrhage patients, 29% were reportedly treated by neurosurgeons, ranging from 5% in Sweden to 79% in Japan, with three neurosurgeons per thousand strokes, ranging from 0.1 in Ethiopia to 24 in South Korea. Most countries had a stroke society (86%) while only 10 (21%) had a degree or subspecialty for stroke medicine. Conclusions Stroke doctor numbers, background specialties, and opportunities to specialize in stroke vary across the globe. Most countries have a scientific society to pursue advancement of stroke medicine, but few have stroke curricula.

Child-Mediated Stroke Communication: findings from Hip Hop Stroke.

PubMed

Williams, Olajide; DeSorbo, Alexandra; Noble, James; Gerin, William

2012-01-01

Low thrombolysis rates for acute ischemic stroke are linked to delays in seeking immediate treatment due to low public stroke awareness. We aimed to assess whether "Child-Mediated Stroke Communication" could improve stroke literacy of parents of children enrolled in a school-based stroke literacy program called Hip Hop Stroke. Parents of children aged 9 to 12 years from 2 public schools in Harlem, New York City, were recruited to participate in stroke literacy questionnaires before and after their child's participation in Hip Hop Stroke, a novel Child-Mediated Stroke Communication intervention delivered in school auditoriums. Parental recall of stroke information communicated through their child was assessed 1-week after the intervention. Fifth and sixth grade students (n=182) were enrolled into Hip Hop Stroke. One hundred two parents were approached in person to participate; 75 opted to participate and 71 completed both the pretest and post-test (74% response rate and 95% retention rate). Parental stroke literacy improved after the program; before the program, 3 parents of 75 (3.9%) were able to identify the 5 cardinal stroke symptoms, distracting symptom (chest pains), and had an urgent action plan (calling 911) compared with 21 of 71 parents (29.6%) postintervention (P<0.001). The FAST mnemonic was known by 2 (2.7%) of participants before the program versus 29 (41%) after program completion (P<0.001). Knowledge of stroke signs and symptoms remains low among residents of this high-risk population. The use of Child-Mediated Stroke Communication suggests that school children aged 9 to 12 years may be effective conduits of critical stroke knowledge to their parents.

Systolic blood pressure, arterial rigidity, and risk of stroke. The Framingham study.

PubMed

Kannel, W B; Wolf, P A; McGee, D L; Dawber, T R; McNamara, P; Castelli, W P

1981-03-27

Based on prospective data from the Framingham study relating systolic pressure, diastolic pressure, age, and pulse-wave configuration to future stroke incidence, it would appear that isolated systolic hypertension predisposes to stroke independent of arterial rigidity. The prevalence of isolated systolic hypertension increased with age and with the degree of blunting of the dicrotic notch in the pulse wave. Subjects with isolated systolic hypertension experienced two to four times as many strokes as did normotensive persons. While diastolic pressure is related to stroke incidence, in the subject with systolic hypertension, the diastolic component adds little to risk assessment and in men, in this subgroup, appears unrelated to stroke incidence.

Characteristics of spinal cord stroke in clinical neurology.

PubMed

Romi, Fredrik; Naess, Halvor

2011-01-01

Spinal cord stroke accounts for about 0.3% of all strokes in our department. Thirty-two patients (15 males, 17 females; mean age 63.3 years) treated in the period 1995-2010 were included. Patients underwent thorough investigation including the use of different stroke scales (National Institute of Health Stroke Scale, Barthel Index and modified Rankin Scale). Twenty-eight patients had infarctions, 3 had hemorrhages, and 1 had arterio-venous fistula. Twenty-eight spinal cord strokes were spontaneous, 2 were secondary to aorta aneurysms, and 2 post surgery. Biphasic ictus was seen in 17% of all spontaneous infarctions. Younger age, male gender, hypertension, diabetes mellitus, and higher blood glucose on admission regardless of diabetes mellitus, were risk factors associated with more severe spinal cord stroke. Treatment and prevention of these risk factors should be essential in spinal cord stroke. We recommend a clinical classification into upper (cervical) and lower (thoracic or medullary conus) spinal cord strokes. Patients with upper strokes in this study had more severe strokes initially, but they had a better prognosis. Therefore it is important to identify this patient group.Acute sensory spinal cord deficit symptoms, common initial symptoms in biphasic spinal cord strokes, should be considered as possible spinal cord stroke, especially when preceded by radiating pain between the shoulders. Copyright © 2011 S. Karger AG, Basel.

Society of Vascular and Interventional Neurology (SVIN) Stroke Interventional Laboratory Consensus (SILC) Criteria: A 7M Management Approach to Developing a Stroke Interventional Laboratory in the Era of Stroke Thrombectomy for Large Vessel Occlusions

PubMed Central

Shams, Tanzila; Zaidat, Osama; Yavagal, Dileep; Xavier, Andrew; Jovin, Tudor; Janardhan, Vallabh

2016-01-01

Brain attack care is rapidly evolving with cutting-edge stroke interventions similar to the growth of heart attack care with cardiac interventions in the last two decades. As the field of stroke intervention is growing exponentially globally, there is clearly an unmet need to standardize stroke interventional laboratories for safe, effective, and timely stroke care. Towards this goal, the Society of Vascular and Interventional Neurology (SVIN) Writing Committee has developed the Stroke Interventional Laboratory Consensus (SILC) criteria using a 7M management approach for the development and standardization of each stroke interventional laboratory within stroke centers. The SILC criteria include: (1) manpower: personnel including roles of medical and administrative directors, attending physicians, fellows, physician extenders, and all the key stakeholders in the stroke chain of survival; (2) machines: resources needed in terms of physical facilities, and angiography equipment; (3) materials: medical device inventory, medications, and angiography supplies; (4) methods: standardized protocols for stroke workflow optimization; (5) metrics (volume): existing credentialing criteria for facilities and stroke interventionalists; (6) metrics (quality): benchmarks for quality assurance; (7) metrics (safety): radiation and procedural safety practices. PMID:27610118

Outboard Motor Maximizes Power and Dependability

NASA Technical Reports Server (NTRS)

2008-01-01

Developed by Jonathan Lee, a structural materials engineer at Marshall Space Flight Center, and PoShou Chen, a scientist with Huntsville, Alabama-based Morgan Research Corporation, MSFC-398 is a high-strength aluminum alloy able to operate at high temperatures. MSFC-398 was licensed for marine applications by Bombardier Recreational Products Inc., and is now found in the complete line of Evinrude E-TEC outboard motors, a line of two-stroke motors that maintain the power and dependability of a two-stroke with the refinement of a four-stroke.

The effect of music-movement therapy on physical and psychological states of stroke patients.

PubMed

Jun, Eun-Mi; Roh, Young Hwa; Kim, Mi Ja

2013-01-01

This study evaluated the effects of combined music-movement therapy on physical and psychological functioning of hospitalised stroke patients. Few studies have focused on music-movement therapy's effects on physical and psychological functioning of stroke patients. A quasi-experimental design with pre- and post-tests was used. A convenience sample was used: patients hospitalised for stroke and within two weeks of the onset of stroke were randomised to either an experimental group (received music-movement therapy in their wheelchairs for 60 minutes three times per week for 8 weeks) or control group (received only routine treatment). The effect of music-movement therapy was assessed in terms of physical outcomes (range of motion, muscle strength and activities of daily living) and psychological outcomes (mood states, depression), measured in both groups pre- and post-test. The experimental group had significantly increased shoulder flexion and elbow joint flexion in physical function and improved mood state in psychological function, compared with the control group. Early rehabilitation of hospitalised stroke patients within two weeks of the onset of stroke was effective by using music-movement therapy. It improved their mood state and increased shoulder flexion and elbow joint flexion. The findings of this study suggest that rehabilitation for stroke patients should begin as early as possible, even during their hospitalisation. Nursing practice should incorporate the concept of combining music and movements to improve stroke patients' physical and psychological states starting from the acute phase. © 2012 Blackwell Publishing Ltd.

A comparison of stroke rehabilitation; data from two national cohorts.

PubMed

Bērziņa, G; Vētra, A; Sunnerhagen, K S

2016-10-01

Inpatient rehabilitation is a commonly used complex intervention to improve a person's independence after stroke. Evaluation and comparison of the effects of routine clinical practice could provide a contribution towards optimization of stroke care. The aim of this study is to describe results of inpatient rehabilitation as a complex intervention for persons after stroke and explore possible differences between two countries. Data from 1055 Latvian and 1748 Swedish adult patients after stroke receiving inpatient rehabilitation, during 2011-2013, were used for this retrospective cohort study. Qualitative description of systems, as well as information on basic medical and sociodemographic information, and organizational aspects were reported. Change in the Functional Independence Measure during rehabilitation was investigated. In six domains of the instrument, the shifts for three levels of dependence were analysed using ordinal regression analysis. The components of stroke care seem to be similar in Latvia and Sweden. However, the median time since stroke onset until the start of rehabilitation was 13 weeks in Latvia and 2 weeks in Sweden. The median length of rehabilitation was 12 and 49 days, respectively. The level of dependency at start, time since stroke onset and length of the period had an impact on the results of the rehabilitation. Although components of the rehabilitation are reported as being the same, characteristics and the outcome of the inpatient rehabilitation are different. Therefore, comparison of stroke rehabilitation between countries requires caution. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Moving with music for stroke rehabilitation: a sonification feasibility study.

PubMed

Scholz, Daniel S; Rhode, Sönke; Großbach, Michael; Rollnik, Jens; Altenmüller, Eckart

2015-03-01

Gross-motor impairments are common after stroke, but efficacious and motivating therapies for these impairments are scarce. We present a novel musical sonification therapy especially designed to retrain gross-motor functions. Four stroke patients were included in a clinical pre-post feasibility study and were trained with our sonification training. Patients' upper-extremity functions and their psychological states were assessed before and after training. The four patients were subdivided into two groups, with both groups receiving 9 days of musical sonification therapy (music group, MG) or a sham sonification training (control group, CG). The only difference between these training protocols was that, in the CG, no sound was played back. During the training the patients initially explored the acoustic effects of their arm movements, and at the end of the training the patients played simple melodies by moving their arms. The two patients in the MG improved in nearly all motor function tests after the training. They also reported in the stroke impact scale, which assesses well-being, memory, thinking, and social participation, to be less impaired by the stroke. The two patients in the CG did benefit less from the movement training. Taken together, musical sonification may be a promising therapy for impairments after stroke. © 2015 New York Academy of Sciences.

Retrieval Practice Fails to Insulate Episodic Memories against Interference after Stroke.

PubMed

Pastötter, Bernhard; Eberle, Hanna; Aue, Ingo; Bäuml, Karl-Heinz T

2017-01-01

Recent work in cognitive psychology showed that retrieval practice of previously studied information can insulate this information against retroactive interference from subsequently studied other information in healthy individuals. The present study examined whether this beneficial effect of interference reduction is also present in patients with stroke. Twenty-two patients with stroke, 4.6 months post injury on average, and 22 healthy controls participated in the experiment. In each of two experimental sessions, participants first studied a list of items (list 1) and then underwent a practice phase in which the list 1 items were either restudied or retrieval practiced. Participants then either studied a second list of items (list 2) or fulfilled an unrelated distractor task. Recall of the two lists' items was assessed in a final criterion test. Results showed that, in healthy controls, additional study of list 2 items impaired final recall of list 1 items in the restudy condition but not in the retrieval practice condition. In contrast, in patients with stroke, list 2 learning impaired final list 1 recall in both conditions. The results indicate that retrieval practice insulated the tested information against retroactive interference in healthy controls, but failed to do so in patients with stroke. Possible implications of the findings for the understanding of long-term memory impairment after stroke are discussed.

Multicylinder Diesel Engine Tests with Unstabilized Water-in-Fuel Emulsions

DOT National Transportation Integrated Search

1981-06-01

Two diesel engines representative of the four-stroke cycle and two-stroke cycle main propulsion units installed in U.S. Coast Guard WPB class cutters were operated in a test environment in an attempt to demonstrate significant fuel savings associated...

Uncooled Infrared Imaging Face Recognition Using Kernel-Based Feature Vector Selection

DTIC Science & Technology

2006-09-01

j ij i jCI j G G p s t id g id p P t p P P ≥ = = ∀ ∈ (4.10) A visualization of that trade-off relationship is depicted in Figure 4.2...X_train_proj a value a_f a_g end t_hat(:,step)=(pp1(:,1))/sqrt(.2*sum(s2)) end 131 clear A1 A2 Num_replic dim1

NACA Conference on Turbojet Engines for Supersonic Propulsion. A Compilation of Technical Material Presented

DTIC Science & Technology

1953-10-01

turbojet Pngine with a turbine cooled by compressor air involves several design pruilems that do not e~ist in an uncooled turbo - jet engine . Careful...facilitate testing the sheet-metal blades in the turbojet engine , bases were formed by removing the solid airfoil portion from the standard turbine blade ...OF TURBINE BLADES by J. C. Freche 6. APPLICATION AND OPERATION OF AIR-COOLED TURBINES IN TURBOJET ENGINES

Materials Research of Perovskite Thin Films for Uncooled Infrared (IR) Detectors

DTIC Science & Technology

2011-07-01

Today April 2010, 5 (2), 99–105. 4. Livingston, F. E.; Helvajian , H . Laser Processing Architecture for Improved Material Processing. in Laser...crystalline final perovskite (BaTiO3) in only 3 h , representing a significantly increased throughput compared to previous results using vapor...Plane Arrays; ARL-TR-5389; U.S. Army Research Laboratory: Adelphi, MD, November 2010. 5. Wemple, S. H . Phys. Rev. B 1970, 2, 2679. 6. Xu, J

Monolithic Silicon Microbolometer Materials for Uncooled Infrared Detectors

DTIC Science & Technology

2015-05-21

covered by an active sensing material, and G is the thermal conductance of the supporting legs. Another important figure of merit is the noise...have a low thermal conductance to maximize thermal isolation from the environment. The legs also have a thin film of metal which serve as...fabricated array, glass substrates (≈ 2 mm thick) were used due to their low thermal conductivity and therefore a lower ability to transport heat away

Motor Recovery After Subcortical Stroke Depends on Modulation of Extant Motor Networks.

PubMed

Sharma, Nikhil; Baron, Jean-Claude

2015-01-01

Stroke is the leading cause of long-term disability. Functional imaging studies report widespread changes in movement-related cortical networks after stroke. Whether these are a result of stroke-specific cognitive processes or reflect modulation of existing movement-related networks is unknown. Understanding this distinction is critical in establishing more effective restorative therapies after stroke. Using multivariate analysis (tensor-independent component analysis - TICA), we map the neural networks involved during motor imagery (MI) and executed movement (EM) in subcortical stroke patients and age-matched controls. Twenty subcortical stroke patients and 17 age-matched controls were recruited. They were screened for their ability to carry out MI (Chaotic MI Assessment). The fMRI task was a right-hand finger-thumb opposition sequence (auditory-paced 1 Hz; 2, 3, 4, 5, 2…). Two separate runs were acquired (MI and rest and EM and rest; block design). There was no distinction between groups or tasks until the last stage of analysis, which allowed TICA to identify independent components (ICs) that were common or distinct to each group or task with no prior assumptions. TICA defined 28 ICs. ICs representing artifacts were excluded. ICs were only included if the subject scores were significant (for either EM or MI). Seven ICs remained that involved the primary and secondary motor networks. All ICs were shared between the stroke and age-matched controls. Five ICs were common to both tasks and three were exclusive to EM. Two ICs were related to motor recovery and one with time since stroke onset, but all were shared with age-matched controls. No IC was exclusive to stroke patients. We report that the cortical networks in stroke patients that relate to recovery of motor function represent modulation of existing cortical networks present in age-matched controls. The absence of cortical networks specific to stroke patients suggests that motor adaptation and other potential confounders (e.g., effort and additional muscle use) are not responsible for the changes in the cortical networks reported after stroke. This highlights that recovery of motor function after subcortical stroke involves preexisting cortical networks that could help identify more effective restorative therapies.

A comparison of risk factors and severity of ischemic stroke in female and male genders in North-West Iran: A cross-sectional study

PubMed Central

Talebi, Mahnaz; Ghertasi, Mohammad; Taheraghdam, Aliakbar; Andalib, Sasan; Sharifipour, Ehsan

2014-01-01

Background: Gender difference has been reported in stroke risk factors and disease history. The aim of this study was to compare risk factors and the severity of ischemic stroke based upon modified Rankin Scale (mRS) and hospital mortality between two genders. Methods: In a cross-sectional study, 341 patients (44% males and 56% females with a mean age of 68.94 ± 12.74 years) with ischemic stroke, who were hospitalized in the neurology wards of two referral university hospital of North-West Iran (Imam Reza and Razi Hospitals), from the beginning to the end of 2011 were selected and assessed. Gender difference in terms of demographic findings, vascular risk factors, 7th day mRS, and hospital mortality (during admission) were evaluated. Results: In 2.6% of cases, mRS was found to be less than 2 (favorable) and in 97.4% of cases; mRS was 2-5 (with disability). No significant difference in ischemic stroke severity based on mRS was observed between two genders. There was a significant difference in the rate of hypertension (females = 72.3%, males = 59.3%, P = 0.010), diabetes (females = 28.8%, males = 18.7%, P = 0.030), smoking (females = 6.3%, males = 35.3%, P < 0.001). No significant difference was seen in other risk factors between two genders. There was no significant difference in the mortality rate, which constituted 8.9% and 4.7% in females and males respectively (P = 0.140). Conclusion: The evidence from the present study suggests that despite the existence of some difference between risk-factors in two genders, there was no difference in terms of ischemic stroke severity and mortality rate between two genders. PMID:25632333

A comparison of risk factors and severity of ischemic stroke in female and male genders in North-West Iran: A cross-sectional study.

PubMed

Talebi, Mahnaz; Ghertasi, Mohammad; Taheraghdam, Aliakbar; Andalib, Sasan; Sharifipour, Ehsan

2014-10-06

Gender difference has been reported in stroke risk factors and disease history. The aim of this study was to compare risk factors and the severity of ischemic stroke based upon modified Rankin Scale (mRS) and hospital mortality between two genders. In a cross-sectional study, 341 patients (44% males and 56% females with a mean age of 68.94 ± 12.74 years) with ischemic stroke, who were hospitalized in the neurology wards of two referral university hospital of North-West Iran (Imam Reza and Razi Hospitals), from the beginning to the end of 2011 were selected and assessed. Gender difference in terms of demographic findings, vascular risk factors, 7(th) day mRS, and hospital mortality (during admission) were evaluated. In 2.6% of cases, mRS was found to be less than 2 (favorable) and in 97.4% of cases; mRS was 2-5 (with disability). No significant difference in ischemic stroke severity based on mRS was observed between two genders. There was a significant difference in the rate of hypertension (females = 72.3%, males = 59.3%, P = 0.010), diabetes (females = 28.8%, males = 18.7%, P = 0.030), smoking (females = 6.3%, males = 35.3%, P < 0.001). No significant difference was seen in other risk factors between two genders. There was no significant difference in the mortality rate, which constituted 8.9% and 4.7% in females and males respectively (P = 0.140). The evidence from the present study suggests that despite the existence of some difference between risk-factors in two genders, there was no difference in terms of ischemic stroke severity and mortality rate between two genders.

Concordance and discordance between measured and perceived balance and the effect on gait speed and falls following stroke

PubMed Central

Liphart, Jodi; Gallichio, Joann; Tilson, Julie K; Pei, Qinglin; Wu, Samuel S; Duncan, Pamela W

2016-01-01

Objective To ascertain the existence of discordance between perceived and measured balance in persons with stroke and to examine the impact on walking speed and falls. Design A secondary analysis of a phase three, multicentered randomized controlled trial examining walking recovery following stroke. Subjects A total of 352 participants from the Locomotor Experience Applied Post-Stroke (LEAPS) trial. Methods Participants were categorized into four groups: two concordant and two discordant groups in relation to measured and perceived balance. Number and percentage of individuals with concordance and discordance were evaluated at two and 12 months. Walking speed and fall incidence between groups were examined. Main measures Perceived balance was measured by the Activity-specific Balance Confidence scale, measured balance was determined by the Berg Balance Scale and gait speed was measured by the 10-meter walk test. Results Discordance was present for 35.8% of participants at two months post-stroke with no statistically significant change in proportion at 12 months. Discordant participants with high perceived balance and low measured balance walked 0.09 m/s faster at two months than participants with concordant low perceived and measured balance (p < 0.05). Discordant participants with low perceived balance and high measured balance walked 0.15 m/s slower than those that were concordant with high perceived and measured balance (p ⩽ 0.0001) at 12 months. Concordant participants with high perceived and measured balance walked fastest and had fewer falls. Conclusions Discordance existed between perceived and measured balance in one-third of individuals at two and 12 months post-stroke. Perceived balance impacted gait speed but not fall incidence. PMID:25810426

Early versus delayed rehabilitation treatment in hemiplegic patients with ischemic stroke: proprioceptive or cognitive approach?

PubMed

Morreale, Manuela; Marchione, Pasquale; Pili, Antonio; Lauta, Antonella; Castiglia, Stefano F; Spallone, Aldo; Pierelli, Francesco; Giacomini, Patrizia

2016-02-01

Early/intensive mobilization may improve functional recovery after stroke but it is not clear which kind of "mobilization" is more effective. Proprioceptive neuromuscular facilitation (PNF) and cognitive therapeutic exercise (CTE) are widespread applied in post-stroke rehabilitation but their efficacy and safety have not been systematically investigated. To compare PNF and CTE methods in a two different time setting (early versus standard approach) in order to evaluate different role of time and techniques in functional recovery after acute ischemic stroke. We designed a prospectical multicenter blinded interventional study of early versus standard approach with two different methods by means of both PNF and CTE. A discrete stroke-dedicated area for out-of-thrombolysis patients, connected with two different comprehensive stroke centres in two different catchment areas. Three hundred and forty consecutive stroke patient with first ever sub-cortical ischemic stroke in the mean cerebral artery (MCA) territory and contralateral hemiplegia admitted within 6 and 24 hours from symptoms onset. All patients were randomly assigned by means of a computer generated randomization sequence in blocks of 4 to one to the 4 interventional groups: early versus delayed rehabilitation programs with Kabat's schemes or Perfetti's technique. Patients in both delayed group underwent to a standard protocol in the acute phase. disability at 3-12 months. Disability measures: modified Rankin Score and Barthel Index. Safety outcome: immobility-related adverse events. Six-Minute Walking Test, Motricity Index, Mini-Mental State Examination, Beck Depression Inventory. Disability was not different between groups at 3 months but Barthel Index significantly changed between early versus delayed groups at 12 months (P=0.01). Six-Minute Walking Test (P=0.01) and Motricity Index in both upper (P=0.01) and lower limbs (P=0.001) increased in early versus delayed groups regardless rehabilitation schedule. A time-dependent effect of rehabilitation on post stroke motor recovery was observed, particularly in lower limb improvement. According to our results, rehabilitation technique seems not to affect long term motor recovery. These results show a significant effect of time but not of technique that may impact the decision making in the acute phase of care.

Reliability of center of pressure measures within and between sessions in individuals post-stroke and healthy controls.

PubMed

Gray, Vicki L; Ivanova, Tanya D; Garland, S Jayne

2014-01-01

Knowing the reliability of the center of pressure (COP) is important for interpreting balance deficits post-stroke, especially when the balance deficits can necessitate the use of short duration trials. The novel aspect of this reliability study was to examine the center of pressure measures using two adjacent force platforms between and within sessions in stroke and controls. After stroke, it is important to understand the contribution of the paretic and non-paretic leg to the motor control of standing balance. Because there is a considerable body of knowledge on COP reliability on a single platform, we chose to examine reliability using two adjacent platforms which has not been examined previously in stroke. Twenty participants post-stroke and 22 controls performed an arm raise, load drop and quiet stance balance task while standing on two adjacent force platforms, on two separate days. Intraclass correlations coefficient (ICC2,1) and percentage standard error of measurement (SEM%) were calculated for COP velocity, ellipse area, anterior-posterior (AP) displacement, and medial-lateral (ML) displacement. Between sessions, COP velocity was the most reliable with high ICCs and low SEM% across groups and tasks and ellipse area was less reliable with low ICCs across groups and tasks. COP measures were less reliable during the arm raise than load drop post-stroke. Within session reliability was high for COP velocity and ML displacement requiring no more than six trials across tasks. The COP velocity was the most reliable measure with high ICCs between sessions and the high reliability was achieved with fewer trials in both groups in a single session. Copyright © 2014 Elsevier B.V. All rights reserved.

[Acute treatment and secondary prophylaxis of ischemic stroke : An excellent example for personalized medicine].

PubMed

Wachter, R; Gröschel, K

2018-03-01

About a quarter of a million people in Germany suffer a stroke every year. Stroke is the most dreaded cardiovascular disease, even before myocardial infarction and heart failure. In the last two to three years, significant progress has been made in acute treatment, secondary prophylaxis in patients with patent foramen ovale, and the interdisciplinary evaluation of atrial fibrillation as the cause of the stroke. These new findings allow for more precise treatment.

A task-specific interactive game-based virtual reality rehabilitation system for patients with stroke: a usability test and two clinical experiments.

PubMed

Shin, Joon-Ho; Ryu, Hokyoung; Jang, Seong Ho

2014-03-06

Virtual reality (VR) is not commonly used in clinical rehabilitation, and commercial VR gaming systems may have mixed effects in patients with stroke. Therefore, we developed RehabMaster™, a task-specific interactive game-based VR system for post-stroke rehabilitation of the upper extremities, and assessed its usability and clinical efficacy. A participatory design and usability tests were carried out for development of RehabMaster with representative user groups. Two clinical trials were then performed. The first was an observational study in which seven patients with chronic stroke received 30 minutes of RehabMaster intervention per day for two weeks. The second was a randomised controlled trial of 16 patients with acute or subacute stroke who received 10 sessions of conventional occupational therapy only (OT-only group) or conventional occupational therapy plus 20 minutes of RehabMaster intervention (RehabMaster + OT group). The Fugl-Meyer Assessment score (FMA), modified Barthel Index (MBI), adverse effects, and drop-out rate were recorded. The requirements of a VR system for stroke rehabilitation were established and incorporated into RehabMaster. The reported advantages from the usability tests were improved attention, the immersive flow experience, and individualised intervention. The first clinical trial showed that the RehabMaster intervention improved the FMA (P = .03) and MBI (P = .04) across evaluation times. The second trial revealed that the addition of RehabMaster intervention tended to enhance the improvement in the FMA (P = .07) but did not affect the improvement in the MBI. One patient with chronic stroke left the trial, and no adverse effects were reported. The RehabMaster is a feasible and safe VR system for enhancing upper extremity function in patients with stroke.

A task-specific interactive game-based virtual reality rehabilitation system for patients with stroke: a usability test and two clinical experiments

PubMed Central

2014-01-01

Background Virtual reality (VR) is not commonly used in clinical rehabilitation, and commercial VR gaming systems may have mixed effects in patients with stroke. Therefore, we developed RehabMaster™, a task-specific interactive game-based VR system for post-stroke rehabilitation of the upper extremities, and assessed its usability and clinical efficacy. Methods A participatory design and usability tests were carried out for development of RehabMaster with representative user groups. Two clinical trials were then performed. The first was an observational study in which seven patients with chronic stroke received 30 minutes of RehabMaster intervention per day for two weeks. The second was a randomised controlled trial of 16 patients with acute or subacute stroke who received 10 sessions of conventional occupational therapy only (OT-only group) or conventional occupational therapy plus 20 minutes of RehabMaster intervention (RehabMaster + OT group). The Fugl-Meyer Assessment score (FMA), modified Barthel Index (MBI), adverse effects, and drop-out rate were recorded. Results The requirements of a VR system for stroke rehabilitation were established and incorporated into RehabMaster. The reported advantages from the usability tests were improved attention, the immersive flow experience, and individualised intervention. The first clinical trial showed that the RehabMaster intervention improved the FMA (P = .03) and MBI (P = .04) across evaluation times. The second trial revealed that the addition of RehabMaster intervention tended to enhance the improvement in the FMA (P = .07) but did not affect the improvement in the MBI. One patient with chronic stroke left the trial, and no adverse effects were reported. Conclusions The RehabMaster is a feasible and safe VR system for enhancing upper extremity function in patients with stroke. PMID:24597650

Performance of e-ASPECTS software in comparison to that of stroke physicians on assessing CT scans of acute ischemic stroke patients.

PubMed

Herweh, Christian; Ringleb, Peter A; Rauch, Geraldine; Gerry, Steven; Behrens, Lars; Möhlenbruch, Markus; Gottorf, Rebecca; Richter, Daniel; Schieber, Simon; Nagel, Simon

2016-06-01

The Alberta Stroke Program Early CT score (ASPECTS) is an established 10-point quantitative topographic computed tomography scan score to assess early ischemic changes. We compared the performance of the e-ASPECTS software with those of stroke physicians at different professional levels. The baseline computed tomography scans of acute stroke patients, in whom computed tomography and diffusion-weighted imaging scans were obtained less than two hours apart, were retrospectively scored by e-ASPECTS as well as by three stroke experts and three neurology trainees blinded to any clinical information. The ground truth was defined as the ASPECTS on diffusion-weighted imaging scored by another two non-blinded independent experts on consensus basis. Sensitivity and specificity in an ASPECTS region-based and an ASPECTS score-based analysis as well as receiver-operating characteristic curves, Bland-Altman plots with mean score error, and Matthews correlation coefficients were calculated. Comparisons were made between the human scorers and e-ASPECTS with diffusion-weighted imaging being the ground truth. Two methods for clustered data were used to estimate sensitivity and specificity in the region-based analysis. In total, 34 patients were included and 680 (34 × 20) ASPECTS regions were scored. Mean time from onset to computed tomography was 172 ± 135 min and mean time difference between computed tomographyand magnetic resonance imaging was 41 ± 31 min. The region-based sensitivity (46.46% [CI: 30.8;62.1]) of e-ASPECTS was better than three trainees and one expert (p ≤ 0.01) and not statistically different from another two experts. Specificity (94.15% [CI: 91.7;96.6]) was lower than one expert and one trainee (p < 0.01) and not statistically different to the other four physicians. e-ASPECTS had the best Matthews correlation coefficient of 0.44 (experts: 0.38 ± 0.08 and trainees: 0.19 ± 0.05) and the lowest mean score error of 0.56 (experts: 1.44 ± 1.79 and trainees: 1.97 ± 2.12). e-ASPECTS showed a similar performance to that of stroke experts in the assessment of brain computed tomographys of acute ischemic stroke patients with the Alberta Stroke Program Early CT score method. © 2016 World Stroke Organization.

Infrared negative luminescent devices and higher operating temperature detectors

NASA Astrophysics Data System (ADS)

Nash, G. R.; Gordon, N. T.; Hall, D. J.; Ashby, M. K.; Little, J. C.; Masterton, G.; Hails, J. E.; Giess, J.; Haworth, L.; Emeny, M. T.; Ashley, T.

2004-01-01

Infrared LEDs and negative luminescent devices, where less light is emitted than in equilibrium, have been attracting an increasing amount of interest recently. They have a variety of applications, including as a ‘source’ of IR radiation for gas sensing; radiation shielding for, and non-uniformity correction of, high sensitivity staring infrared detectors; and dynamic infrared scene projection. Similarly, infrared (IR) detectors are used in arrays for thermal imaging and, discretely, in applications such as gas sensing. Multi-layer heterostructure epitaxy enables the growth of both types of device using designs in which the electronic processes can be precisely controlled and techniques such as carrier exclusion and extraction can be implemented. This enables detectors to be made which offer good performance at higher than normal operating temperatures, and efficient negative luminescent devices to be made which simulate a range of effective temperatures whilst operating uncooled. In both cases, however, additional performance benefits can be achieved by integrating optical concentrators around the diodes to reduce the volume of semiconductor material, and so minimise the thermally activated generation-recombination processes which compete with radiative mechanisms. The integrated concentrators are in the form of Winston cones, which can be formed using an iterative dry etch process involving methane/hydrogen and oxygen. We present results on negative luminescence in the mid- and long-IR wavebands, from devices made from indium antimonide and mercury cadmium telluride, where the aim is sizes greater than 1 cm×1 cm. We also discuss progress on, and the potential for, operating temperature and/or sensitivity improvement of detectors, where very high-performance imaging is anticipated from systems which require no mechanical cooling.

Infrared negative luminescent devices and higher operating temperature detectors

NASA Astrophysics Data System (ADS)

Nash, Geoff R.; Gordon, Neil T.; Hall, David J.; Little, J. Chris; Masterton, G.; Hails, J. E.; Giess, J.; Haworth, L.; Emeny, Martin T.; Ashley, Tim

2004-02-01

Infrared LEDs and negative luminescent devices, where less light is emitted than in equilibrium, have been attracting an increasing amount of interest recently. They have a variety of applications, including as a ‘source" of IR radiation for gas sensing; radiation shielding for and non-uniformity correction of high sensitivity starring infrared detectors; and dynamic infrared scene projection. Similarly, IR detectors are used in arrays for thermal imaging and, discretely, in applications such as gas sensing. Multi-layer heterostructure epitaxy enables the growth of both types of device using designs in which the electronic processes can be precisely controlled and techniques such as carrier exclusion and extraction can be implemented. This enables detectors to be made which offer good performance at higher than normal operating temperatures, and efficient negative luminescent devices to be made which simulate a range of effective temperatures whilst operating uncooled. In both cases, however, additional performance benefits can be achieved by integrating optical concentrators around the diodes to reduce the volume of semiconductor material, and so minimise the thermally activated generation-recombination processes which compete with radiative mechanisms. The integrated concentrators are in the form of Winston cones, which can be formed using an iterative dry etch process involving methane/hydrogen and oxygen. We will present results on negative luminescence in the mid and long IR wavebands, from devices made from indium antimonide and mercury cadmium telluride, where the aim is sizes greater than 1cm x 1cm. We will also discuss progress on, and the potential for, operating temperature and/or sensitivity improvement of detectors, where very higher performance imaging is anticipated from systems which require no mechanical cooling.

Infrared Negative Luminescent Devices and Higher Operating Temperature Detectors

NASA Astrophysics Data System (ADS)

Ashley, Tim

2003-03-01

Infrared LEDs and negative luminescent devices, where less light is emitted than in equilibrium, have been attracting an increasing amount of interest recently. They have a variety of applications, including as a source' of IR radiation for gas sensing; radiation shielding for and non-uniformity correction of high sensitivity starring infrared detectors; and dynamic infrared scene projection. Similarly, IR detectors are used in arrays for thermal imaging and, discretely, in applications such as gas sensing. Multi-layer heterostructure epitaxy enables the growth of both types of device using designs in which the electronic processes can be precisely controlled and techniques such as carrier exclusion and extraction can be implemented. This enables detectors to be made which offer good performance at higher than normal operating temperatures, and efficient negative luminescent devices to be made which simulate a range of effective temperatures whilst operating uncooled. In both cases, however, additional performance benefits can be achieved by integrating optical concentrators around the diodes to reduce the volume of semiconductor material, and so minimise the thermally activated generation-recombination processes which compete with radiative mechanisms. The integrated concentrators are in the form of Winston cones, which can be formed using an iterative dry etch process involving methane/hydrogen and oxygen. We will present results on negative luminescence in the mid and long IR wavebands, from devices made from indium antimonide and mercury cadmium telluride, where the aim is sizes greater than 1cm x 1cm. We will also discuss progress on, and the potential for, operating temperature and/or sensitivity improvement of detectors, where very high performance imaging is anticipated from systems which require no mechanical cooling.

Developing a Cantonese Version of Birmingham Cognitive Screen for Stroke Survivors in Hong Kong

ERIC Educational Resources Information Center

Kong, Anthony Pak-Hin; Chan, John; Lau, Johnny King-L.; Bickerton, Wai-Ling; Weekes, Brendan; Humphreys, Glyn

2018-01-01

The "Birmingham Cognitive Screen" (BCoS) is a neuropsychological battery designed to assess impairment to a variety of cognitive domains including language in patients with brain injuries. Twenty-two stroke participants and 16 gender-, age-, and education-matched controls were recruited in Hong Kong. The stroke participants were…

[Perioperative stroke following transurethral resection of prostate: high index of suspicion and stabilization of physiological parameters can save lives].

PubMed

Nag, Deb Sanjay; Chatterjee, Abhishek; Samaddar, Devi Prasad; Agarwal, Ajay

2017-01-09

We report a case of a 72 year old hypertensive male who developed severe hypertension followed by neurological deterioration in the immediate postoperative period after transurethral resection of prostate. While arterial blood gas and laboratory tests excluded transurethral resection of prostate syndrome or any other metabolic cause, reduction of blood pressure failed to ameliorate the symptoms. A cranial CT done 4hours after the onset of neurological symptoms revealed bilateral gangliocapsular and right thalamic infarcts. Oral aspirin was advised to prevent early recurrent stroke. Supportive treatment and mechanical ventilation ensured physiological stability and the patient recovered completely over the next few days without any residual neurological deficit. Copyright © 2016. Publicado por Elsevier Editora Ltda.

Stroke risk perception among participants of a stroke awareness campaign

PubMed Central

Kraywinkel, Klaus; Heidrich, Jan; Heuschmann, Peter U; Wagner, Markus; Berger, Klaus

2007-01-01

Background Subjective risk factor perception is an important component of the motivation to change unhealthy life styles. While prior studies assessed cardiovascular risk factor knowledge, little is known about determinants of the individual perception of stroke risk. Methods Survey by mailed questionnaire among 1483 participants of a prior public stroke campaign in Germany. Participants had been informed about their individual stroke risk based on the Framingham stroke risk score. Stroke risk factor knowledge, perception of lifetime stroke risk and risk factor status were included in the questionnaire, and the determinants of good risk factor knowledge and high stroke risk perception were identified using logistic regression models. Results Overall stroke risk factor knowledge was good with 67–96% of the participants recognizing established risk factors. The two exceptions were diabetes (recognized by 49%) and myocardial infarction (57%). Knowledge of a specific factor was superior among those affected by it. 13% of all participants considered themselves of having a high stroke risk, 55% indicated a moderate risk. All major risk factors contributed significantly to the perception of being at high stroke risk, but the effects of age, sex and education were non-significant. Poor self-rated health was additionally associated with high individual stroke risk perception. Conclusion Stroke risk factor knowledge was high in this study. The self perception of an increased stroke risk was associated with established risk factors as well as low perception of general health. PMID:17371603

CHARACTERIZATION OF EMISSIONS FROM HAND-HELD TWO-STROKE ENGINES

EPA Science Inventory

Despite their extremely high organic and particulate matter emission rates, two-stroke engines remain among the least studied of engine types. Such studies are rare because they are costly to perform. Results reported in this paper were obtained using a facility that shares e...

Direct Quantification of Methane Emissions Across the Supply Chain: Identification of Mitigation Targets

NASA Astrophysics Data System (ADS)

Darzi, M.; Johnson, D.; Heltzel, R.; Clark, N.

2017-12-01

Researchers at West Virginia University's Center for Alternative Fuels, Engines, and Emissions have recently participated in a variety of studies targeted at direction quantification of methane emissions from across the natural gas supply chain. These studies included assessing methane emissions from heavy-duty vehicles and their fuel stations, active unconventional well sites - during both development and production, natural gas compression and storage facilities, natural gas engines - both large and small, two- and four-stroke, and low-throughput equipment associated with coal bed methane wells. Engine emissions were sampled using conventional instruments such as Fourier transform infrared spectrometers and heated flame ionization detection analyzers. However, to accurately quantify a wide range of other sources beyond the tailpipe (both leaks and losses), a full flow sampling system was developed, which included an integrated cavity-enhanced absorption spectrometer. Through these direct quantification efforts and analysis major sources of methane emissions were identified. Technological solutions and best practices exist or could be developed to reduce methane emissions by focusing on the "lowest-hanging fruit." For example, engine crankcases from across the supply chain should employ vent mitigation systems to reduce methane and other emissions. An overview of the direct quantification system and various campaign measurements results will be presented along with the identification of other targets for additional mitigation.

Functional status of acute stroke patients in University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia.

PubMed

Rameezan, B A R; Zaliha, O

2005-12-01

Stroke is a leading cause of death and disability in most developed countries and developing nations. Majority of the stroke survivors are left with significant physical and cognitive impairments. In addition to the improved acute stroke care, they often benefit from rehabilitation in improving their function. This was the first study done to document function for post stroke patients in Malaysia. It was prospective study conducted to document functional status of acute stroke patients upon admission, discharge and at 3 months post stroke. Assessment of functional status for these patients are based on their activities of daily living and ambulation i.e. self-care, sphincter control, mobility, locomotion, communication and social cognition. It is also aimed to describe their demographic and clinical characteristics. Correlation of functional status at 3 months post stroke with the initial severity of stroke was also explored. A total of fifty-one patients with acute stroke in University Malaya Medical Centre (UMMC) were recruited. The patient's age ranged from 38 to 83 years with a mean of 60.2 years. Thirty-six patients (71%) were first stroke sufferers and fifteen patients (29%) had recurrent stroke. At discharge from acute stay, 13% of patients were able to ambulate with aids and 87% needed assistance for ambulation in varying degrees. Eighty-two percent of patients showed improvement in overall function (both motor and cognition) at 3 months post stroke. Sixty percent of patients were independent in ambulation and 40% required assistance. Significant correlation was seen between the initial severity of stroke and functional status at 3 months post stroke. Functional status of patients with stroke has improved at 3 months post stroke. A comprehensive rehabilitation medicine programme should be incorporated into management of stroke patients to expedite functional recovery and improve patient's independence.

Feedback-controlled robotics-assisted treadmill exercise to assess and influence aerobic capacity early after stroke: a proof-of-concept study.

PubMed

Stoller, Oliver; Schindelholz, Matthias; Bichsel, Lukas; Schuster, Corina; de Bie, Rob A; de Bruin, Eling D; Hunt, Kenneth J

2014-07-01

The majority of post-stroke individuals suffer from low exercise capacity as a secondary reaction to immobility. The aim of this study was to prove the concept of feedback-controlled robotics-assisted treadmill exercise (RATE) to assess aerobic capacity and guide cardiovascular exercise in severely impaired individuals early after stroke. Subjects underwent constant load and incremental exercise testing using a human-in-the-loop feedback system within a robotics-assisted exoskeleton (Lokomat, Hocoma AG, CH). Inclusion criteria were: stroke onset ≤8 weeks, stable medical condition, non-ambulatory status, moderate motor control of the lower limbs and appropriate cognitive function. Outcome measures included oxygen uptake kinetics, peak oxygen uptake (VO2peak), gas exchange threshold (GET), peak heart rate (HRpeak), peak work rate (Ppeak) and accuracy of reaching target work rate (P-RMSE). Three subjects (18-42 d post-stroke) were included. Oxygen uptake kinetics during constant load ranged from 42.0 to 60.2 s. Incremental exercise testing showed: VO2peak range 19.7-28.8 ml/min/kg, GET range 11.6-12.7 ml/min/kg, and HRpeak range 115-161 bpm. Ppeak range was 55.2-110.9 W and P-RMSE range was 3.8-7.5 W. The concept of feedback-controlled RATE for assessment of aerobic capacity and guidance of cardiovascular exercise is feasible. Further research is warranted to validate the method on a larger scale. Aerobic capacity is seriously reduced in post-stroke individuals as a secondary reaction to immobility. Robotics-assisted walking devices may have substantial clinical relevance regarding assessment and improvement of aerobic capacity early after stroke. Feedback-controlled robotics-assisted treadmill exercise represents a new concept for cardiovascular assessment and intervention protocols for severely impaired individuals.

Aspirin and extended-release dipyridamole versus clopidogrel for recurrent stroke.

PubMed

Sacco, Ralph L; Diener, Hans-Christoph; Yusuf, Salim; Cotton, Daniel; Ounpuu, Stephanie; Lawton, William A; Palesch, Yuko; Martin, Reneé H; Albers, Gregory W; Bath, Philip; Bornstein, Natan; Chan, Bernard P L; Chen, Sien-Tsong; Cunha, Luis; Dahlöf, Björn; De Keyser, Jacques; Donnan, Geoffrey A; Estol, Conrado; Gorelick, Philip; Gu, Vivian; Hermansson, Karin; Hilbrich, Lutz; Kaste, Markku; Lu, Chuanzhen; Machnig, Thomas; Pais, Prem; Roberts, Robin; Skvortsova, Veronika; Teal, Philip; Toni, Danilo; Vandermaelen, Cam; Voigt, Thor; Weber, Michael; Yoon, Byung-Woo

2008-09-18

Recurrent stroke is a frequent, disabling event after ischemic stroke. This study compared the efficacy and safety of two antiplatelet regimens--aspirin plus extended-release dipyridamole (ASA-ERDP) versus clopidogrel. In this double-blind, 2-by-2 factorial trial, we randomly assigned patients to receive 25 mg of aspirin plus 200 mg of extended-release dipyridamole twice daily or to receive 75 mg of clopidogrel daily. The primary outcome was first recurrence of stroke. The secondary outcome was a composite of stroke, myocardial infarction, or death from vascular causes. Sequential statistical testing of noninferiority (margin of 1.075), followed by superiority testing, was planned. A total of 20,332 patients were followed for a mean of 2.5 years. Recurrent stroke occurred in 916 patients (9.0%) receiving ASA-ERDP and in 898 patients (8.8%) receiving clopidogrel (hazard ratio, 1.01; 95% confidence interval [CI], 0.92 to 1.11). The secondary outcome occurred in 1333 patients (13.1%) in each group (hazard ratio for ASA-ERDP, 0.99; 95% CI, 0.92 to 1.07). There were more major hemorrhagic events among ASA-ERDP recipients (419 [4.1%]) than among clopidogrel recipients (365 [3.6%]) (hazard ratio, 1.15; 95% CI, 1.00 to 1.32), including intracranial hemorrhage (hazard ratio, 1.42; 95% CI, 1.11 to 1.83). The net risk of recurrent stroke or major hemorrhagic event was similar in the two groups (1194 ASA-ERDP recipients [11.7%], vs. 1156 clopidogrel recipients [11.4%]; hazard ratio, 1.03; 95% CI, 0.95 to 1.11). The trial did not meet the predefined criteria for noninferiority but showed similar rates of recurrent stroke with ASA-ERDP and with clopidogrel. There is no evidence that either of the two treatments was superior to the other in the prevention of recurrent stroke. (ClinicalTrials.gov number, NCT00153062.) 2008 Massachusetts Medical Society

Screening methods for post-stroke visual impairment: a systematic review.

PubMed

Hanna, Kerry Louise; Hepworth, Lauren Rachel; Rowe, Fiona

2017-12-01

To provide a systematic overview of the various tools available to screen for post-stroke visual impairment. A review of the literature was conducted including randomised controlled trials, controlled trials, cohort studies, observational studies, systematic reviews and retrospective medical note reviews. All languages were included and translation was obtained. Participants included adults ≥18 years old diagnosed with a visual impairment as a direct cause of a stroke. We searched a broad range of scholarly online resources and hand-searched articles registers of published, unpublished and on-going trials. Search terms included a variety of MESH terms and alternatives in relation to stroke and visual conditions. Study selection was performed by two authors independently. The quality of the evidence and risk of bias were assessed using the STROBE, GRACE and PRISMA statements. A total of 25 articles (n = 2924) were included in this review. Articles appraised reported on tools screening solely for visual impairments or for general post-stroke disabilities inclusive of vision. The majority of identified tools screen for visual perception including visual neglect (VN), with few screening for visual acuity (VA), visual field (VF) loss or ocular motility (OM) defects. Six articles reported on nine screening tools which combined visual screening assessment alongside screening for general stroke disabilities. Of these, three included screening for VA; three screened for VF loss; three screened for OM defects and all screened for VN. Two tools screened for all visual impairments. A further 19 articles were found which reported on individual vision screening tests in stroke populations; two for VF loss; 11 for VN and six for other visual perceptual defects. Most tools cannot accurately account for those with aphasia or communicative deficits, which are common problems following a stroke. There is currently no standardised visual screening tool which can accurately assess all potential post-stroke visual impairments. The current tools screen for only a number of potential stroke-related impairments, which means many visual defects may be missed. The sensitivity of those which screen for all impairments is significantly lowered when patients are unable to report their visual symptoms. Future research is required to develop a tool capable of assessing stroke patients which encompasses all potential visual deficits and can also be easily performed by both the patients and administered by health care professionals in order to ensure all stroke survivors with visual impairment are accurately identified and managed. Implications for Rehabilitation Over 65% of stroke survivors will suffer from a visual impairment, whereas 45% of stroke units do not assess vision. Visual impairment significantly reduces the quality of life, such as being unable to return to work, driving and depression. This review outlines the available screening methods to accurately identify stroke survivors with visual impairments. Identifying visual impairment after stroke can aid general rehabilitation and thus, improve the quality of life for these patients.

Sony PlayStation EyeToy elicits higher levels of movement than the Nintendo Wii: implications for stroke rehabilitation.

PubMed

Neil, A; Ens, S; Pelletier, R; Jarus, T; Rand, D

2013-02-01

Virtual reality (VR) is an emerging trend in stroke rehabilitation. VR gaming consoles in stroke intervention have been shown to increase motivation and enjoyment during exercise. The amount and intensity of movements elicited using these consoles are unknown. The aims of this study were: (1) to quantify the amount and intensity of movement elicited from both hands of two groups of individuals ([chronic stroke and without a disability [healthy]); (2) to determine the effect of console (Wii/EyeToy) and group (stroke/healthy) on the amount and intensity of upper extremity movement; (3) to determine the effect of console (Wii/EyeToy) and group (stroke/healthy) on the usability and VR experience. A cross-sectional design was taken. Outpatient rehabilitation setting and healthy participant's homes. Participants included ten adults with stroke and ten adults without a disability. Participants experienced two games from each console. Amount and intensity of movement was measured using accelerometers on both wrists, while the virtual experience and usability was determined with questionnaires. No significant differences were found between the consoles usability and experience. EyeToy elicited significantly greater activity count than Wii among the healthy participants (P=0.028) and significantly greater movement intensity in both the stroke (P=0.005) and healthy (P=0.005) groups. Both consoles rated high for usability, enjoyment and satisfaction highlighting their suitability for a range of individuals in stroke rehabilitation. EyeToy provides increased movement and movement intensity. Both consoles are suitable for use in stroke rehabilitation however this information can be helpful to clinicians while selecting a gaming console according to the type and intensity of movements that he/she aims to encourage during therapy.

Increased risk of brain cancer incidence in stroke patients: a clinical case series, population-based and longitudinal follow-up study.

PubMed

Chen, Chih-Wei; Cheng, Tain-Junn; Ho, Chung-Han; Wang, Jhi-Joung; Weng, Shih-Feng; Hou, Ya-Chin; Cheng, Hung-Chi; Chio, Chung-Ching; Shan, Yan-Shen; Chang, Wen-Tsan

2017-12-12

Stroke and brain cancer are two distinct diseases. However, the relationship between both diseases has rarely been examined. This study investigated the longitudinal risk for developing brain cancer in stroke patients. To study this, we first reviewed the malignant gliomas previously with or without stroke using brain magnetic resonance imaging (MRI) images and the past histories. Two ischemic stroke patients before the malignant glioma were identified and belonged to the glioblastoma mutiforme (GBM). Particularly, both GBM specimens displayed strong hypoxia-inducible factor 1α (HIF-1α) expression in immunohistochemical (IHC) staining. To elucidate the significance of this relationship, we then used a nationwide population-based cohort in Taiwan to investigate the risk for the incidence of brain cancer in patients previously with or without stroke. The incidence of all tumors in the stroke group was lower than that in the control group with an adjusted hazard ratio (HR) of 0.79 (95% confidence interval [CI]: 0.74-0.84) in both gender and age older than 60 years. But the stroke patients had higher risk of developing only brain cancer with an adjusted HR of 3.09 (95% CI: 1.80-5.30), and otherwise had lower risk of developing head and neck, digestive, respiratory, bone and skin, as well as other tumors, all with p<0.05. After stratification by gender and age, the female and aged 40-60 year old stroke patients had higher risk of developing brain cancer with an adjusted HR of 7.41 (95% CI: 3.30-16.64) and 16.34 (95% CI: 4.45-62.13), respectively, both with p<0.05. Patients with stroke, in particular female and age 40-60 years old, have an increased risk for developing brain cancer.

Prestroke Proteomic Changes in Cerebral Microvessels in Stroke-Prone, Transgenic[hCETP]-Hyperlipidemic, Dahl Salt-Sensitive Hypertensive Rats

PubMed Central

Bergerat, Agnes; Decano, Julius; Wu, Chang-Jiun; Choi, Hyungwon; Nesvizhskii, Alexey I; Moran, Ann Marie; Ruiz-Opazo, Nelson; Steffen, Martin; Herrera, Victoria LM

2011-01-01

Stroke is the third leading cause of death in the United States with high rates of morbidity among survivors. The search to fill the unequivocal need for new therapeutic approaches would benefit from unbiased proteomic analyses of animal models of spontaneous stroke in the prestroke stage. Since brain microvessels play key roles in neurovascular coupling, we investigated prestroke microvascular proteome changes. Proteomic analysis of cerebral cortical microvessels (cMVs) was done by tandem mass spectrometry comparing two prestroke time points. Metaprotein-pathway analyses of proteomic spectral count data were done to identify risk factor–induced changes, followed by QSPEC-analyses of individual protein changes associated with increased stroke susceptibility. We report 26 cMV proteome profiles from male and female stroke-prone and non–stroke-prone rats at 2 months and 4.5 months of age prior to overt stroke events. We identified 1,934 proteins by two or more peptides. Metaprotein pathway analysis detected age-associated changes in energy metabolism and cell-to-microenvironment interactions, as well as sex-specific changes in energy metabolism and endothelial leukocyte transmigration pathways. Stroke susceptibility was associated independently with multiple protein changes associated with ischemia, angiogenesis or involved in blood brain barrier (BBB) integrity. Immunohistochemical analysis confirmed aquaporin-4 and laminin-α1 induction in cMVs, representative of proteomic changes with >65 Bayes factor (BF), associated with stroke susceptibility. Altogether, proteomic analysis demonstrates significant molecular changes in ischemic cerebral microvasculature in the prestroke stage, which could contribute to the observed model phenotype of microhemorrhages and postischemic hemorrhagic transformation. These pathways comprise putative targets for translational research of much needed novel diagnostic and therapeutic approaches for stroke. PMID:21519634

Change in stroke incidence from a population-based intervention trial in three urban communities in China.

PubMed

Wang, Wen-Zhi; Jiang, Bin; Wu, Sheng-Ping; Hong, Zhen; Yang, Qi-Dong; Sander, J W; Du, Xiao-Li; Bao, Qiu-Jiu

2007-01-01

Stroke has been the main cause of death in most urban residents in China since the 1990s. A community-based intervention trial carried out in China aimed to reduce the incidence and mortality of stroke. In 1991, two well-matched communities each with approximately 50,000 people were selected as intervention or control communities in the urban areas of Beijing, Shanghai and Changsha. Regular health education and health promotion activities were carried out between 1991 and 2000 in the intervention communities but no special action was taken in the control communities. Both fatal and nonfatal stroke cases were meticulously registered during the study in the two communities to assess the effect of long-term intervention. The trend in stroke incidence and the effect of intervention on stroke incidence were analyzed using a Poisson regression model adjusted for age, sex, year and city. Between 1991 and 2000, 2,273 first-ever stroke cases were registered in the intervention communities and 3,015 in the control communities. Geographic variation and changes in the incidence of stroke and its subtypes were found among these 3 cities. Through 10 years of intervention, incidence risks of all, ischemic and hemorrhagic strokes decreased by 11.4% (relative risk 0.8959; 95% confidence interval, CI, 0.8483-0.9460; p < 0.0001), 13.2% (relative risk 0.8676; 95% CI 0.8054-0.9345; p = 0.0002) and 7.2% (relative risk 0.9283; 95% CI 0.8517-1.0117; p = 0.0899), respectively, in the intervention compared with control communities. Accordingly, comprehensive community-based intervention measures could effectively reduce the incidence of stroke in the population. Copyright (c) 2007 S. Karger AG, Basel.

The neural substrates of impaired finger tapping regularity after stroke.

PubMed

Calautti, Cinzia; Jones, P Simon; Guincestre, Jean-Yves; Naccarato, Marcello; Sharma, Nikhil; Day, Diana J; Carpenter, T Adrian; Warburton, Elizabeth A; Baron, Jean-Claude

2010-03-01

Not only finger tapping speed, but also tapping regularity can be impaired after stroke, contributing to reduced dexterity. The neural substrates of impaired tapping regularity after stroke are unknown. Previous work suggests damage to the dorsal premotor cortex (PMd) and prefrontal cortex (PFCx) affects externally-cued hand movement. We tested the hypothesis that these two areas are involved in impaired post-stroke tapping regularity. In 19 right-handed patients (15 men/4 women; age 45-80 years; purely subcortical in 16) partially to fully recovered from hemiparetic stroke, tri-axial accelerometric quantitative assessment of tapping regularity and BOLD fMRI were obtained during fixed-rate auditory-cued index-thumb tapping, in a single session 10-230 days after stroke. A strong random-effect correlation between tapping regularity index and fMRI signal was found in contralesional PMd such that the worse the regularity the stronger the activation. A significant correlation in the opposite direction was also present within contralesional PFCx. Both correlations were maintained if maximal index tapping speed, degree of paresis and time since stroke were added as potential confounds. Thus, the contralesional PMd and PFCx appear to be involved in the impaired ability of stroke patients to fingertap in pace with external cues. The findings for PMd are consistent with repetitive TMS investigations in stroke suggesting a role for this area in affected-hand movement timing. The inverse relationship with tapping regularity observed for the PFCx and the PMd suggests these two anatomically-connected areas negatively co-operate. These findings have implications for understanding the disruption and reorganization of the motor systems after stroke. Copyright (c) 2009 Elsevier Inc. All rights reserved.

Rowing Crew Coordination Dynamics at Increasing Stroke Rates

PubMed Central

2015-01-01

In rowing, perfect synchronisation is important for optimal performance of a crew. Remarkably, a recent study on ergometers demonstrated that antiphase crew coordination might be mechanically more efficient by reducing the power lost to within-cycle velocity fluctuations of the boat. However, coupled oscillator dynamics predict the stability of the coordination to decrease with increasing stroke rate, which in case of antiphase may eventually yield breakdowns to in-phase. Therefore, this study examined the effects of increasing stroke rate on in- and antiphase crew coordination in rowing dyads. Eleven experienced dyads rowed on two mechanically coupled ergometers on slides, which allowed the ergometer system to move back and forth as one ‘boat’. The dyads performed a ramp trial in both in- and antiphase pattern, in which stroke rates gradually increased from 30 strokes per minute (spm) to as fast as possible in steps of 2 spm. Kinematics of rowers, handles and ergometers were captured. Two dyads showed a breakdown of antiphase into in-phase coordination at the first stroke rate of the ramp trial. The other nine dyads reached between 34–42 spm in antiphase but achieved higher rates in in-phase. As expected, the coordinative accuracy in antiphase was worse than in in-phase crew coordination, while, somewhat surprisingly, the coordinative variability did not differ between the patterns. Whereas crew coordination did not substantially deteriorate with increasing stroke rate, stroke rate did affect the velocity fluctuations of the ergometers: fluctuations were clearly larger in the in-phase pattern than in the antiphase pattern, and this difference significantly increased with stroke rate. Together, these results suggest that although antiphase rowing is less stable (i.e., less resistant to perturbation), potential on-water benefits of antiphase over in-phase rowing may actually increase with stroke rate. PMID:26185987

Two-stroke S.I. engine competitive to four-stroke engine in terms of the exhaust emission

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

Pavletic, R.; Trenc, F.

1994-09-01

A model engine with disintegrated working cycle was built. Its operation is not autonomous; compression of the working air is performed separately outside the engine by the compressed-air line supply. Pre-compressed charge together with the injected fuel is introduced in the combustion chamber. The model engine makes possible to determine indicated performance characteristics and its emission capability. Effective measured engine characteristics are of course not comparable with those obtained by a practical engine. The model presented is a two-stroke cycle engine. Exhaust emission picture of the presented engine is comparable with the emission of a modern four-stroke engine. 2 refs.,more » 13 figs., 2 tabs.« less

Key performance indicators for stroke from the Ministry of Health of Brazil: benchmarking and indicator parameters.

PubMed

Lange, Marcos C; Braga, Gabriel Pereira; Nóvak, Edison M; Harger, Rodrigo; Felippe, Maria Justina Dalla Bernardina; Canever, Mariana; Dall'Asta, Isabella; Rauen, Jordana; Bazan, Rodrigo; Zetola, Viviane

2017-06-01

All 16 KPIs were analyzed, including the percentage of patients admitted to the stroke unit, venous thromboembolism prophylaxis in the first 48 hours after admission, pneumonia and hospital mortality due to stroke, and hospital discharge on antithrombotic therapy in patients without cardioembolic mechanism. Both centers admitted over 80% of the patients in their stroke unit. The incidence of venous thromboembolism prophylaxis was > 85%, that of in-hospital pneumonia was < 13%, the hospital mortality for stroke was < 15%, and the hospital discharge on antithrombotic therapy was > 70%. Our results suggest using the parameters of all of the 16 KPIs required by the Ministry of Health of Brazil, and the present results for the two stroke units for future benchmarking.

Performance Factors Related to the Different Tennis Backhand Groundstrokes: A Review

PubMed Central

Genevois, Cyril; Reid, Machar; Rogowski, Isabelle; Crespo, Miguel

2015-01-01

The backhand is one of the two basic groundstrokes in tennis and can be played both with one or two hands, with topspin or backspin. Despite its variety of derivatives, the scientific literature describing the backhand groundstroke production has not been reviewed as extensively as with the serve and the forehand. The purpose of this article is to review the research describing the mechanics of one and two-handed backhands, with a critical focus on its application to clinicians and coaches. One hundred and thirty four articles satisfied a key word search (tennis, backhand) in relevant databases and manual search, with only 61 of those articles considered directly relevant to our review. The consensus of this research supports major differences between both the one- and two-handed strokes, chiefly about their respective contributions of trunk rotation and the role of the non-dominant upper extremity. Two-handed backhand strokes rely more on trunk rotation for the generation of racquet velocity, while the one-handed backhands utilize segmental rotations of the upper limb to develop comparable racquet speeds. There remains considerable scope for future research to examine expertise, age and/or gender-related kinematic differences to strengthen the practitioner’s understanding of the key mechanical considerations that may shape the development of proficient backhand strokes. Key points One-and two-handed backhands require different motor coordination Two-handed backhand strokes rely more on trunk rotation for racquet velocity generation, whereas one-handed backhand strokes rely more on segmental rotations of the upper limb Players using a two-handed backhand should learn early a slice one-handed backhand because of the different co-ordination pattern involved Equipment scaling is a great tool for coaches to learn early proper one-handed backhand strokes Future research related to the interaction between backhand technique, gender and skill level is needed PMID:25729308

Shielding of substations against direct lightning strokes by shield wires

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

Chowdhuri, P.

1994-01-01

A new analysis for shielding outdoor substations against direct lightning strokes by shield wires is proposed. The basic assumption of this proposed method is that any lightning stroke which penetrates the shields will cause damage. The second assumption is that a certain level of risk of failure must be accepted, such as one or two failures per 100 years. The proposed method, using electrogeometric model, was applied to design shield wires for two outdoor substations: (1) 161-kV/69-kV station, and (2) 500-kV/161-kV station. The results of the proposed method were also compared with the shielding data of two other substations.

Nursing care for stroke patients: A survey of current practice in 11 European countries.

PubMed

Tulek, Zeliha; Poulsen, Ingrid; Gillis, Katrin; Jönsson, Ann-Cathrin

2018-02-01

To conduct a survey of the clinical nursing practice in European countries in accordance with the European Stroke Strategies 2006 and to examine to what extent the European Stroke Strategies have been implemented in stroke care nursing in Europe. Stroke is a leading cause of death and disability globally. Optimal organisation of interdisciplinary stroke care is expected to ameliorate outcome after stroke. Consequently, universal access to stroke care based on evidence-based guidelines is a priority. This study is a descriptive cross-sectional survey. A questionnaire comprising 61 questions based on the European Stroke Strategies and scientific evidence in nursing practice was distributed to representatives of the European Association of Neuroscience Nurses, who sent the questionnaire to nurses active in stroke care. The questionnaire covered the following areas of stroke care: organisation of stroke services, management of acute stroke and prevention including basic care and nursing, and secondary prevention. Ninety-two nurses in stroke care in 11 European countries participated in the survey. Within the first 48 hr after stroke onset, 95% monitor patients regularly, 94% start mobilisation after 24 hr when patients are stable, and 89% assess patients' ability to swallow. Change of position for immobile patients is followed by 73%, and postvoid residual urine volume is measured by 85%. Some aspects needed improvement, for example, staff education (70%), education for patients/families/carers (55%) and individual care plans in secondary prevention (62%). The participating European countries comply well with the European Stroke Strategies guidelines, particularly in the acute stroke care, but not all stroke units have reached optimal development in all aspects of stroke care nursing. Our study may provide clinical administrators and nurses in stroke care with information that may contribute to improved compliance with the European Stroke Strategies and evidence-based guidelines. © 2017 John Wiley & Sons Ltd.

Determining Polarities Of Distant Lightning Strokes

NASA Technical Reports Server (NTRS)

Blakeslee, Richard J.; Brook, Marx

1990-01-01

Method for determining polarities of lightning strokes more than 400 km away. Two features of signal from each stroke correlated. New method based on fact each stroke observed thus far for which polarity determined unambiguously, initial polarity of tail same as polarity of initial deflection before initial-deflection signal altered by propagation effects. Receiving station equipped with electric-field-change antenna coupled to charge amplifier having time constant of order of 1 to 10 seconds. Output of amplifier fed to signal-processing circuitry, which determines initial polarity of tail.

Correlated peak relative light intensity and peak current in triggered lightning subsequent return strokes

NASA Technical Reports Server (NTRS)

Idone, V. P.; Orville, R. E.

1985-01-01

The correlation between peak relative light intensity L(R) and stroke peak current I(R) is examined for 39 subsequent return strokes in two triggered lightning flashes. One flash contained 19 strokes and the other 20 strokes for which direct measurements were available of the return stroke peak current at ground. Peak currents ranged from 1.6 to 21 kA. The measurements of peak relative light intensity were obtained from photographic streak recordings using calibrated film and microsecond resolution. Correlations, significant at better than the 0.1 percent level, were found for several functional relationships. Although a relation between L(R) and I(R) is evident in these data, none of the analytical relations considered is clearly favored. The correlation between L(R) and the maximum rate of current rise is also examined, but less correlation than between L(R) and I(R) is found. In addition, the peak relative intensity near ground is evaluated for 22 dart leaders, and a mean ratio of peak dart leader to peak return stroke relative light intensity was found to be 0.1 with a range of 0.02-0.23. Using two different methods, the peak current near ground in these dart leaders is estimated to range from 0.1 to 6 kA.

Flexor and extensor muscle tone evaluated using the quantitative pendulum test in stroke and parkinsonian patients.

PubMed

Huang, Han-Wei; Ju, Ming-Shaung; Lin, Chou-Ching K

2016-05-01

The aim of this study was to evaluate the flexor and extensor muscle tone of the upper limbs in patients with spasticity or rigidity and to investigate the difference in hypertonia between spasticity and rigidity. The two experimental groups consisted of stroke patients and parkinsonian patients. The control group consisted of age and sex-matched normal subjects. Quantitative upper limb pendulum tests starting from both flexed and extended joint positions were conducted. System identification with a simple linear model was performed and model parameters were derived. The differences between the three groups and two starting positions were investigated by these model parameters and tested by two-way analysis of variance. In total, 57 subjects were recruited, including 22 controls, 14 stroke patients and 21 parkinsonian patients. While stiffness coefficient showed no difference among groups, the number of swings, relaxation index and damping coefficient showed changes suggesting significant hypertonia in the two patient groups. There was no difference between these two patient groups. The test starting from the extended position constantly manifested higher muscle tone in all three groups. In conclusion, the hypertonia of parkinsonian and stroke patients could not be differentiated by the modified pendulum test; the elbow extensors showed a higher muscle tone in both control and patient groups; and hypertonia of both parkinsonian and stroke patients is velocity dependent. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evaluation of the Finis Swimsense® and the Garmin Swim™ activity monitors for swimming performance and stroke kinematics analysis

PubMed Central

Mooney, Robert; Corley, Gavin; Godfrey, Alan; Osborough, Conor; ÓLaighin, Gearóid

2017-01-01

Aims The study aims were to evaluate the validity of two commercially available swimming activity monitors for quantifying temporal and kinematic swimming variables. Methods Ten national level swimmers (5 male, 5 female; 15.3±1.3years; 164.8±12.9cm; 62.4±11.1kg; 425±66 FINA points) completed a set protocol comprising 1,500m of swimming involving all four competitive swimming strokes. Swimmers wore the Finis Swimsense and the Garmin Swim activity monitors throughout. The devices automatically identified stroke type, swim distance, lap time, stroke count, stroke rate, stroke length and average speed. Video recordings were also obtained and used as a criterion measure to evaluate performance. Results A significant positive correlation was found between the monitors and video for the identification of each of the four swim strokes (Garmin: X2 (3) = 31.292, p<0.05; Finis:X2 (3) = 33.004, p<0.05). No significant differences were found for swim distance measurements. Swimming laps performed in the middle of a swimming interval showed no significant difference from the criterion (Garmin: bias -0.065, 95% confidence intervals -3.828–6.920; Finis bias -0.02, 95% confidence intervals -3.095–3.142). However laps performed at the beginning and end of an interval were not as accurately timed. Additionally, a statistical difference was found for stroke count measurements in all but two occasions (p<0.05). These differences affect the accuracy of stroke rate, stroke length and average speed scores reported by the monitors, as all of these are derived from lap times and stroke counts. Conclusions Both monitors were found to operate with a relatively similar performance level and appear suited for recreational use. However, issues with feature detection accuracy may be related to individual variances in stroke technique. It is reasonable to expect that this level of error would increase when the devices are used by recreational swimmers rather than elite swimmers. Further development to improve accuracy of feature detection algorithms, specifically for lap time and stroke count, would also increase their suitability within competitive settings. PMID:28178301

Intravenous Thrombolysis for Stroke and Presumed Stroke in Human Immunodeficiency Virus-Infected Adults: A Retrospective, Multicenter US Study.

PubMed

AbdelRazek, Mahmoud A; Gutierrez, Jose; Mampre, David; Cervantes-Arslanian, Anna; Ormseth, Cora; Haussen, Diogo; Thakur, Kiran T; Lyons, Jennifer L; Smith, Bryan R; O'Connor, Owen; Willey, Joshua Z; Mateen, Farrah J

2018-01-01

Human immunodeficiency virus (HIV) infection has been shown to increase both ischemic and hemorrhagic stroke risks, but there are limited data on the safety and outcomes of intravenous thrombolysis with tPA (tissue-type plasminogen activator) for acute ischemic stroke in HIV-infected patients. A retrospective chart review of intravenous tPA-treated HIV patients who presented with acute stroke symptoms was performed in 7 large inner-city US academic centers (various search years between 2000 and 2017). We collected data on HIV, National Institutes of Health Stroke Scale score, ischemic stroke risk factors, opportunistic infections, intravenous drug abuse, neuroimaging findings, and modified Rankin Scale score at last follow-up. We identified 33 HIV-infected patients treated with intravenous tPA (mean age, 51 years; 24 men), 10 of whom were stroke mimics. Sixteen of 33 (48%) patients had an HIV viral load less than the limit of detection while 10 of 33 (30%) had a CD4 count <200/mm 3 . The median National Institutes of Health Stroke Scale score at presentation was 9, and mean time from symptom onset to tPA was 144 minutes (median, 159). The median modified Rankin Scale score for the 33-patient cohort was 1 and for the 23-patient actual stroke cohort was 2, measured at a median of 90 days poststroke symptom onset. Two patients had nonfatal hemorrhagic transformation (6%; 95% confidence interval, 1%-20%), both in the actual stroke group. Two patients had varicella zoster virus vasculitis of the central nervous system, 1 had meningovascular syphilis, and 7 other patients were actively using intravenous drugs (3 cocaine, 1 heroin, and 3 unspecified), none of whom had hemorrhagic transformation. Most HIV-infected patients treated with intravenous tPA for presumed and actual acute ischemic stroke had no complications, and we observed no fatalities. Stroke mimics were common, and thrombolysis seems safe in this group. We found no data to suggest an increased risk of intravenous tPA-related complications because of concomitant opportunistic infections or intravenous drug abuse. © 2017 American Heart Association, Inc.

Evaluation of the Finis Swimsense® and the Garmin Swim™ activity monitors for swimming performance and stroke kinematics analysis.

PubMed

Mooney, Robert; Quinlan, Leo R; Corley, Gavin; Godfrey, Alan; Osborough, Conor; ÓLaighin, Gearóid

2017-01-01

The study aims were to evaluate the validity of two commercially available swimming activity monitors for quantifying temporal and kinematic swimming variables. Ten national level swimmers (5 male, 5 female; 15.3±1.3years; 164.8±12.9cm; 62.4±11.1kg; 425±66 FINA points) completed a set protocol comprising 1,500m of swimming involving all four competitive swimming strokes. Swimmers wore the Finis Swimsense and the Garmin Swim activity monitors throughout. The devices automatically identified stroke type, swim distance, lap time, stroke count, stroke rate, stroke length and average speed. Video recordings were also obtained and used as a criterion measure to evaluate performance. A significant positive correlation was found between the monitors and video for the identification of each of the four swim strokes (Garmin: X2 (3) = 31.292, p<0.05; Finis:X2 (3) = 33.004, p<0.05). No significant differences were found for swim distance measurements. Swimming laps performed in the middle of a swimming interval showed no significant difference from the criterion (Garmin: bias -0.065, 95% confidence intervals -3.828-6.920; Finis bias -0.02, 95% confidence intervals -3.095-3.142). However laps performed at the beginning and end of an interval were not as accurately timed. Additionally, a statistical difference was found for stroke count measurements in all but two occasions (p<0.05). These differences affect the accuracy of stroke rate, stroke length and average speed scores reported by the monitors, as all of these are derived from lap times and stroke counts. Both monitors were found to operate with a relatively similar performance level and appear suited for recreational use. However, issues with feature detection accuracy may be related to individual variances in stroke technique. It is reasonable to expect that this level of error would increase when the devices are used by recreational swimmers rather than elite swimmers. Further development to improve accuracy of feature detection algorithms, specifically for lap time and stroke count, would also increase their suitability within competitive settings.

Atrial Septal Aneurysm and Patent Foramen Ovale as Risk Factors for Cryptogenic Stroke in Patients Less Than 55 Years of Age: A Study using Transesophageal Echocardiography

NASA Technical Reports Server (NTRS)

Cabanes, L.; Mas, J. L.; Cohen, A.; Amarenco, P.; Cabanes, P. A.; Oubary, P.; Chedru, F.; Guerin, F.; Bousser, M. G.; deRecondo, J.

1993-01-01

Background and Purpose: An association between atrial septal aneurysm and embolic events has been suggested. Atrial septal aneurysm has been shown to be associated with patent foramen ovale and,.in some reports, with mitral valve prolapse. These two latter cardiac disorder; have been identified as potential risk factors for ischemic stroke. The aim of this prospective study was to assess the role of atrial septal aneurysm as an independent risk factor for stroke, especially for cryptogenic stroke. Methods: We studied the prevalence of atrial septal aneurysm, patent foramen ovale, and mitral valve prolapse in 100 consecutive patients <55 years of age with ischemic stroke who underwent extensive etiological investigations. We compared these results with those in a control group of 50 consecutive patients. The diagnosis of atrial septal aneurysm and patent foramen ovale relied on transesophageal echocardiography with a contrast study and that of mitral valve prolapse, on two-dimensional transthoracic echocardiography. Results: Stepwise logistic regression analysis showed that atrial septal aneurysm (odds ratio, 4.3; 95% confidence interval, 1.3 to 14.6; P=.01) and patent foramen ovale (odds ratio, 3.9; 95% confidence interval, 1.5 to 10; P=.003) but not mitral valve prolapse were significantly associated with the diagnosis of cryptogenic stroke. The stroke odds of a patient with both atrial septal aneurysm and patent foramen ovale were 33.3 times (95% confidence interval, 4.1 to 270) the stroke odds of a patient with neither of these cardiac disorders. For a patient with atrial septal aneurysm of >lo-mm excursion, the stroke odds were approximately 8 times the stroke odds of a patient with atrial septal aneurysm of <10 mm. Conclusions: This study shows that atrial septal aneurysm and patent foramen ovale are both significantly associated with cryptogenic stroke and that their association has a marked synergistic effect. Atrial septal aneurysms of >lo-mm excursion are associated with a higher risk of stroke. (Stroke. 1993;24:1865-1873.) KEY WORDS aneurysm echocardiography foramen ovale, patent mitral valve prolapse o young adults

Effects of aspirin plus extended-release dipyridamole versus clopidogrel and telmisartan on disability and cognitive function after recurrent stroke in patients with ischaemic stroke in the Prevention Regimen for Effectively Avoiding Second Strokes (PRoFESS) trial: a double-blind, active and placebo-controlled study

PubMed Central

Diener, Hans-Christoph; Sacco, Ralph L; Yusuf, Salim; Cotton, Daniel; Ôunpuu, Stephanie; Lawton, William A; Palesch, Yuko; Martin, Reneé H; Albers, Gregory W; Bath, Philip; Bornstein, Natan; Chan, Bernard P L; Chen, Sien-Tsong; Cunha, Luis; Dahlöf, Björn; Keyser, Jacques De; Donnan, Geoffrey A; Estol, Conrado; Gorelick, Philip; Gu, Vivian; Hermansson, Karin; Hilbrich, Lutz; Kaste, Markku; Lu, Chuanzhen; Machnig, Thomas; Pais, Prem; Roberts, Robin; Skvortsova, Veronika; Teal, Philip; Toni, Danilo; VanderMaelen, Cam; Voigt, Thor; Weber, Michael; Yoon, Byung-Woo

2009-01-01

Summary Background The treatment of ischaemic stroke with neuroprotective drugs has been unsuccessful, and whether these compounds can be used to reduce disability after recurrent stroke is unknown. The putative neuroprotective effects of antiplatelet compounds and the angiotensin II receptor antagonist telmisartan were investigated in the Prevention Regimen for Effectively Avoiding Second Strokes (PRoFESS) trial. Methods Patients who had had an ischaemic stroke were randomly assigned in a two by two factorial design to receive either 25 mg aspirin (ASA) and 200 mg extended-release dipyridamole (ER-DP) twice a day or 75 mg clopidogrel once a day, and either 80 mg telmisartan or placebo once per day. The predefined endpoints for this substudy were disability after a recurrent stroke, assessed with the modified Rankin scale (mRS) and Barthel index at 3 months, and cognitive function, assessed with the mini-mental state examination (MMSE) score at 4 weeks after randomisation and at the penultimate visit. Analysis was by intention to treat. The study was registered with ClinicalTrials.gov, number NTC00153062. Findings 20 332 patients (mean age 66 years) were randomised and followed-up for a median of 2·4 years. Recurrent strokes occurred in 916 (9%) patients randomly assigned to ASA with ER-DP and 898 (9%) patients randomly assigned to clopidogrel; 880 (9%) patients randomly assigned to telmisartan and 934 (9%) patients given placebo had recurrent strokes. mRS scores were not statistically different in patients with recurrent stroke who were treated with ASA and ER-DP versus clopidogrel (p=0·38), or with telmisartan versus placebo (p=0·61). There was no significant difference in the proportion of patients with recurrent stroke with a good outcome, as measured with the Barthel index, across all treatment groups. Additionally, there was no significant difference in the median MMSE scores, the percentage of patients with an MMSE score of 24 points or less, the percentage of patients with a drop in MMSE score of 3 points or more between 1 month and the penultimate visit, and the number of patients with dementia among the treatment groups. There were no significant differences in the proportion of patients with cognitive impairment or dementia among the treatment groups. Interpretation Disability due to recurrent stroke and cognitive decline in patients with ischaemic stroke were not different between the two antiplatelet regimens and were not affected by the preventive use of telmisartan. Funding Boehringer Ingelheim; Bayer-Schering Pharma (in selected countries); GlaxoSmithKline (in selected countries). PMID:18757238

Post-stroke disability and its predictors among Nigerian stroke survivors.

PubMed

Oyewole, Olufemi O; Ogunlana, Michael O; Oritogun, Kolawole S; Gbiri, Caleb A

2016-10-01

Despite stroke is a major cause of disability, the predictors of the disability among stroke survivors has not been sufficiently delineated. To assess post-stroke disability and determine its predictors among Nigerian stroke survivors. This study involved 121 consecutive stroke survivors with at least 3 months of stroke from two tertiary health institutions in South-Western Nigeria. The World Health Organization Disability Assessment Schedule was used to assess their disability. Socio-demographic and clinical variables were obtained through interview and from their hospital records respectively. Poisson regression was used to examine the predictors. Moderate disability level (44.1 ± 20.5) was observed among the participants. Prevalence of post-stroke disability was high in nine items with scores ranged between 62.0% and 90.1%. There was moderate prevalence of post-stroke disability in 3 items (44.6%-52.1%). When adjusted for sex, prevalence of post-stroke disability followed the same pattern. Being a male and having the affectation of dominant right limbs had 1.08 and 1.46 more likelihood of having disability while being gainfully employed after stroke had 0.81 less likelihood of having disability. Every additional unit of diastolic blood pressure and stroke duration were associated with estimated 0.4% and 0.2% less disability while every one year increased in age was associated with 0.5% increase in disability. Disability in stroke survivors is determined by having right dominant limb affected, increase in blood pressure, longer stroke duration, increase in age and being a male. However, disability in stroke survivors decreases with the stroke survivors engaging in productive lifestyle. Copyright © 2016 Elsevier Inc. All rights reserved.

Risk and mortality of traumatic brain injury in stroke patients: two nationwide cohort studies.

PubMed

Chou, Yi-Chun; Yeh, Chun-Chieh; Hu, Chaur-Jong; Meng, Nai-Hsin; Chiu, Wen-Ta; Chou, Wan-Hsin; Chen, Ta-Liang; Liao, Chien-Chang

2014-01-01

Patients with stroke had higher incidence of falls and hip fractures. However, the risk of traumatic brain injury (TBI) and post-TBI mortality in patients with stroke was not well defined. Our study is to investigate the risk of TBI and post-TBI mortality in patients with stroke. Using reimbursement claims from Taiwan's National Health Insurance Research Database, we conducted a retrospective cohort study of 7622 patients with stroke and 30 488 participants without stroke aged 20 years and older as reference group. Data were collected on newly developed TBI after stroke with 5 to 8 years' follow-up during 2000 to 2008. Another nested cohort study including 7034 hospitalized patients with TBI was also conducted to analyze the contribution of stroke to post-TBI in-hospital mortality. Compared with the nonstroke cohort, the adjusted hazard ratio of TBI risk among patients with stroke was 2.80 (95% confidence interval = 2.58-3.04) during the follow-up period. Patients with stroke had higher mortality after TBI than those without stroke (10.2% vs 3.2%, P < .0001) with an adjusted relative risk (RR) of 1.46 (95% confidence interval = 1.15-1.84). Recurrent stroke (RR = 1.60), hemorrhagic stroke (RR = 1.68), high medical expenditure for stroke (RR = 1.80), epilepsy (RR = 1.79), neurosurgery (RR = 1.94), and hip fracture (RR = 2.11) were all associated with significantly higher post-TBI mortality among patients with stroke. Patients with stroke have an increased risk of TBI and in-hospital mortality after TBI. Various characteristics of stroke severity were all associated with higher post-TBI mortality. Special attention is needed to prevent TBI among these populations.

Sex Differences in Stroke Severity, Symptoms, and Deficits After First-Ever Ischemic Stroke

PubMed Central

Barrett, Kevin M.; Brott, Thomas G.; Brown, Robert D.; Frankel, Michael R.; Worrall, Bradford B.; Silliman, Scott L.; Case, L. Douglas; Rich, Stephen S.; Meschia, James F.

2007-01-01

Objective The purpose of the study was to assess whether there were sex differences in stroke severity, infarct characteristics, symptoms, or the symptoms-deficit relationship at the time of acute stroke presentation. Methods In a prospective study of 505 patients with first-ever ischemic stroke (the Ischemic Stroke Genetics Study), stroke subtype was centrally adjudicated and infarcts were characterized by imaging. Deficits were assessed by National Institutes of Health Stroke Scale and stroke symptoms were assessed using a structured interview. Kappa statistics were generated to assess agreement between the National Institutes of Health Stroke Scale and the structured interview, and a χ2 test was used to assess agreement between the National Institutes of Health Stroke Scale and the structured interview by sex. Results Two hundred seventy-six patients (55%) were men and 229 (45%) were women. Ages ranged from 19 to 94 years (median, 65 years). The mean (±SD) National Institutes of Health Stroke Scale score of 3.8 (±4.5) for men and 4.3 (±5.2) for women was similar (P=.15). No sex difference was observed for the symptoms of numbness, visual deficits, or language. Weakness occurred in a greater proportion of women (69%) than men (59%) (P=.03). Stroke subtype did not differ significantly between sexes (P=.79). Infarct size and location were similar for each sex. The association between symptoms and neurologic deficits did not differ by sex. Conclusions We found no sex difference in stroke severity, stroke subtype, or infarct size and location in patients with incident ischemic stroke. A greater proportion of women presented with weakness; however, similar proportions of men and women presented with other traditional stroke symptoms. PMID:17689390

Optimal Scoring Methods of Hand-Strength Tests in Patients with Stroke

ERIC Educational Resources Information Center

Huang, Sheau-Ling; Hsieh, Ching-Lin; Lin, Jau-Hong; Chen, Hui-Mei

2011-01-01

The purpose of this study was to determine the optimal scoring methods for measuring strength of the more-affected hand in patients with stroke by examining the effect of reducing measurement errors. Three hand-strength tests of grip, palmar pinch, and lateral pinch were administered at two sessions in 56 patients with stroke. Five scoring methods…

Two-dimensional velocity, optical risetime, and peak current estimates for natural positive lightning return strokes

NASA Technical Reports Server (NTRS)

Mach, Douglas M.; Rust, W. D.

1993-01-01

Velocities, optical risetimes, and transmission line model peak currents for seven natural positive return strokes are reported. The average 2D positive return stroke velocity for channel segments of less than 500 m in length starting near the base of the channel is 0.8 +/- 0.3 x 10 exp 8 m/s, which is slower than the present corresponding average velocity for natural negative first return strokes of 1.7 +/- 0.7 x 10 exp 8/s. It is inferred that positive stroke peak currents in the literature, which assume the same velocity as negative strokes, are low by a factor of 2. The average 2D positive return stroke velocity for channel segments of greater than 500 m starting near the base of the channel is 0.9 +/- 0.4 x 10 exp 8 m/s. The corresponding average velocity for the present natural negative first strokes is 1.2 +/- 0.6 x 10 exp 8 m/s. No significant velocity change with height is found for positive return strokes.

Transient ischameic attack/stroke electronic decision support: a 14-month safety audit.

PubMed

Lavin, Timothy L; Ranta, Annemarei

2014-02-01

To assess the safety of a Transient Ischameic Attack (TIA)/Stroke Electronic Decision Support (EDS) tool in the primary care setting intended to aid general practitioners in the timely management of transient ischemic attacks (TIAs). A 14-month safety audit reviewing all patients managed with the help of the TIA/Stroke EDS tool. Major morbidity and mortality were assessed by screening patients for subsequent hospital admissions and investigating potential links to EDS use. Seventy-nine patients were managed with the aid of the TIA/Stroke EDS. EDS use resulted in 8 appropriate immediate hospital admissions because of patients being at high risk of stroke. Three patients had delayed admission, but care was fully guideline based and patients had no adverse outcome. Eleven admissions were unrelated to EDS use. Two deaths occurred; these did not result from inappropriate EDS advice. Results suggest that TIA/Stroke EDS use is not associated with major morbidity or mortality. Larger studies are needed to draw more definite conclusions regarding the utility of this TIA/Stroke EDS in preventing strokes. Copyright © 2014 National Stroke Association. All rights reserved.

Pulmonary tissue volume, cardiac output, and diffusing capacity in sustained microgravity

NASA Technical Reports Server (NTRS)

Verbanck, S.; Larsson, H.; Linnarsson, D.; Prisk, G. K.; West, J. B.; Paiva, M.

1997-01-01

In microgravity (microG) humans have marked changes in body fluids, with a combination of an overall fluid loss and a redistribution of fluids in the cranial direction. We investigated whether interstitial pulmonary edema develops as a result of a headward fluid shift or whether pulmonary tissue fluid volume is reduced as a result of the overall loss of body fluid. We measured pulmonary tissue volume (Vti), capillary blood flow, and diffusing capacity in four subjects before, during, and after 10 days of exposure to microG during spaceflight. Measurements were made by rebreathing a gas mixture containing small amounts of acetylene, carbon monoxide, and argon. Measurements made early in flight in two subjects showed no change in Vti despite large increases in stroke volume (40%) and diffusing capacity (13%) consistent with increased pulmonary capillary blood volume. Late in-flight measurements in four subjects showed a 25% reduction in Vti compared with preflight controls (P < 0.001). There was a concomittant reduction in stroke volume, to the extent that it was no longer significantly different from preflight control. Diffusing capacity remained elevated (11%; P < 0.05) late in flight. These findings suggest that, despite increased pulmonary perfusion and pulmonary capillary blood volume, interstitial pulmonary edema does not result from exposure to microG.

Single nucleotide polymorphisms associated with coronary heart disease predict incident ischemic stroke in the atherosclerosis risk in communities study.

PubMed

Morrison, Alanna C; Bare, Lance A; Luke, May M; Pankow, James S; Mosley, Thomas H; Devlin, James J; Willerson, James T; Boerwinkle, Eric

2008-01-01

Ischemic stroke and coronary heart disease (CHD) may share genetic factors contributing to a common etiology. This study investigates whether 51 single nucleotide polymorphisms (SNPs) associated with CHD in multiple antecedent studies are associated with incident ischemic stroke in the Atherosclerosis Risk in Communities (ARIC) study. From the multiethnic ARIC cohort of 14,215 individuals, 495 validated ischemic strokes were identified. Cox proportional hazards models, adjusted for age and gender, identified three SNPs in Whites and two SNPs in Blacks associated with incident stroke (p

University of Idaho's low-speed flex fuel direct-injected 797cc two-stroke rear drive snowmobile.

DOT National Transportation Integrated Search

2012-06-01

The University of Idahos entry into the 2012 SAE Clean Snowmobile Challenge uses a Ski-Doo XP chassis with a low-speed 797 cc direct-injection two-stroke powered snowmobile modified for flex fuel use on blended ethanol fuel. A battery-less direct ...

Development of an Ethanol Blend Two-Stroke Direct-Injection Snowmobile for Use in the Clean Snowmobile Challenge and National Parks

DOT National Transportation Integrated Search

2010-09-01

The University of Idaho's entry into the 2010 SAE Clean Snowmobile Challenge (CSC) was a direct-injection (DI) two-stroke powered snowmobile modified to use blended ethanol fuel. The modulated and battery-less direct-injection system used to decrease...

Two-stroke-cycle engines for airplanes

NASA Technical Reports Server (NTRS)

Jalbert, J

1926-01-01

Now that the two-stroke-cycle engine has begun to make its appearance in automobiles, it is important to know what services we have a right to expect of it in aeronautics, what conditions must be met by engines of this type for use on airplanes and what has been accomplished.

Methods for LWIR Radiometric Calibration and Characterization

NASA Technical Reports Server (NTRS)

Ryan, Robert; Pagnutti, Mary; Zanoni, Vicki; Harrington, Gary; Howell, Dane; Stewart, Randy

2002-01-01

The utility of a thermal remote sensing system increases with it's ability to retrieve surface temperature or radiance accurately. The radiometer measures the water surface radiant temperature. Combining these measurements with atmospheric pressure, temperature, and water vapor profiles, a top-of-the-atmosphere tradiance estimate can be caluclated with a radiativer transfer code to compare to trhe sensor's output. A novel approach has been developed using an uncooled infrared camera mounted on a boom, to quantify buoy effects.

Real-Time Terahertz Imaging Using a Quantum Cascade Laser and Uncooled Microbolometer Focal Plane Array

DTIC Science & Technology

2008-06-01

reverse magnetron ” design (in which the polarity of the magnetron elements are reversed—such that the cathode constitutes the outer ring; the anode ...included as inset frames within Fig. 20. The dual nature of this figure (reporting both voltage and intensity vs. bias current) is useful in that it...tuned micro- magnetrons [60]-[61]. Conventional magnetrons (such as those used to generate microwaves) have physical dimensions which are excessively

Does touch massage facilitate recovery after stroke? A study protocol of a randomized controlled trial.

PubMed

Lämås, Kristina; Häger, Charlotte; Lindgren, Lenita; Wester, Per; Brulin, Christine

2016-02-04

Despite high quality stroke care, decreased sensorimotor function, anxiety and pain often remain one year after stroke which can lead to impaired health and dependence, as well as higher healthcare costs. Touch massage (TM) has been proven to decrease anxiety and pain, and improve quality of health in other conditions of reduced health, where reduced anxiety seems to be the most pronounced benefit. Thus there are reasons to believe that TM may also reduce anxiety and pain, and improve quality of life after stroke. Further, several studies indicate that somatosensory stimulation can increase sensorimotor function, and it seems feasible to believe that TM could increase independence after stroke. In this study we will evaluate effects of TM after stroke compared to sham treatment. This is a prospective randomized open-labelled control trial with blinded evaluation (PROBE-design). Fifty patients with stroke admitted to stroke units will be randomized (1:1) to either a TM intervention or a non-active transcutaneous electrical nerve stimulation (non-TENS) control group. Ten sessions of 30 min treatments (TM or control) will be administered during two weeks. Assessment of status according to the International Classification of Functioning, Disability and Health (ICF), including body function, activity, and participation. Assessment of body function will include anxiety, pain, and stress response (heart rate variability and salivary cortisol), where anxiety is the primary outcome. Activity will be assessed by means of sensorimotor function and disability, and participation by means of health-related quality of life. Assessments will be made at baseline, after one week of treatment, after two weeks of treatment, and finally a follow-up after two months. The trial has been approved by the Regional Ethical Review Board. TM seems to decrease anxiety and pain, increase health-related quality of life, and improve sensorimotor functions after stroke, but the field is largely unexplored. Considering the documented pleasant effects of massage in general, absence of reported adverse effects, and potential effects in relation to stroke, it is essential to evaluate effects of TM during the sub-acute phase after stroke. The results of this project will hopefully provide important knowledge for evidence-based care. ClinicalTrials.gov: NTC01883947.

Child-Mediated Stroke Communication: Findings from Hip Hop Stroke

PubMed Central

Williams, Olajide; DeSorbo, Alexandra; Noble, James; Gerin, William

2011-01-01

Background and Purpose Low thrombolysis rates for acute ischemic stroke is linked to delays in seeking immediate treatment due to low public stroke awareness. We aimed to assess whether “Child-Mediated Stroke Communication” (CMSC) could improve stroke literacy parents of children enrolled in a school-based stroke literacy program called Hip Hop Stroke (HHS). Methods Parents of children aged 9 to 12 years from two public schools in Harlem, NYC, were recruited to participate in stroke literacy questionnaires before and after their child’s participation in HHS, a novel CMSC intervention delivered in school auditoriums. Parental recall of stroke information communicated through their child was assessed 1-week following the intervention. Results Fifth and Sixth grade students (n =182) were enrolled into HHS. 102 parents were approached in person to participate; 75 opted to participate and 71 completed both pretest and post-test (74% response rate and 95% retention rate). Parental stroke literacy improved after the program: before the program, 3 parents of 75 (3.9%) were able to identify the five cardinal stroke symptoms, distracting symptom (chest pains), and had an urgent action plan (calling 911), compared to 21 of 71 parents (29.6%) post-intervention (p<0.001). The FAST mnemonic was known by 2 (2.7%) of participants before the program vs. 29 (41%) after program completion (p<0.001). Conclusions Knowledge of stroke signs and symptoms remains low among residents of this high-risk population. The use of Child-Mediated Stroke Communication suggests that schoolchildren aged 9-12 may be effective conduits of critical stroke knowledge to their Parents. PMID:22033995

Etiologic Ischemic Stroke Phenotypes in the NINDS Stroke Genetics Network

PubMed Central

Ay, Hakan; Arsava, Ethem Murat; Andsberg, Gunnar; Benner, Thomas; Brown, Robert D.; Chapman, Sherita N.; Cole, John W.; Delavaran, Hossein; Dichgans, Martin; Engström, Gunnar; Giralt-Steinhauer, Eva; Grewal, Raji P.; Gwinn, Katrina; Jern, Christina; Jimenez-Conde, Jordi; Jood, Katarina; Katsnelson, Michael; Kissela, Brett; Kittner, Steven J.; Kleindorfer, Dawn O.; Labovitz, Daniel L.; Lanfranconi, Silvia; Lee, Jin-Moo; Lehm, Manuel; Lemmens, Robin; Levi, Chris; Li, Linxin; Lindgren, Arne; Markus, Hugh S.; McArdle, Patrick F.; Melander, Olle; Norrving, Bo; Peddareddygari, Leema Reddy; Pedersén, Annie; Pera, Joanna; Rannikmäe, Kristiina; Rexrode, Kathryn M.; Rhodes, David; Rich, Stephen S.; Roquer, Jaume; Rosand, Jonathan; Rothwell, Peter M.; Rundek, Tatjana; Sacco, Ralph L.; Schmidt, Reinhold; Schürks, Markus; Seiler, Stephan; Sharma, Pankaj; Slowik, Agnieszka; Sudlow, Cathie; Thijs, Vincent; Woodfield, Rebecca; Worrall, Bradford B.; Meschia, James F.

2014-01-01

Background and Purpose NINDS Stroke Genetics Network (SiGN) is an international consortium of ischemic stroke studies that aims to generate high quality phenotype data to identify the genetic basis of etiologic stroke subtypes. This analysis characterizes the etiopathogenetic basis of ischemic stroke and reliability of stroke classification in the consortium. Methods Fifty-two trained and certified adjudicators determined both phenotypic (abnormal test findings categorized in major etiologic groups without weighting towards the most likely cause) and causative ischemic stroke subtypes in 16,954 subjects with imaging-confirmed ischemic stroke from 12 US studies and 11 studies from 8 European countries using the web-based Causative Classification of Stroke System. Classification reliability was assessed with blinded re-adjudication of 1509 randomly selected cases. Results The distribution of etiologic categories varied by study, age, sex, and race (p<0.001 for each). Overall, only 40% to 54% of cases with a given major ischemic stroke etiology (phenotypic subtype) were classified into the same final causative category with high confidence. There was good agreement for both causative (kappa 0.72, 95%CI:0.69-0.75) and phenotypic classifications (kappa 0.73, 95%CI:0.70-0.75). Conclusions This study demonstrates that etiologic subtypes can be determined with good reliability in studies that include investigators with different expertise and background, institutions with different stroke evaluation protocols and geographic location, and patient populations with different epidemiological characteristics. The discordance between phenotypic and causative stroke subtypes highlights the fact that the presence of an abnormality in a stroke patient does not necessarily mean that it is the cause of stroke. PMID:25378430

Relationship between functional disability and costs one and two years post stroke

PubMed Central

Lekander, Ingrid; Willers, Carl; von Euler, Mia; Lilja, Mikael; Sunnerhagen, Katharina S.; Pessah-Rasmussen, Hélène; Borgström, Fredrik

2017-01-01

Background and purpose Stroke affects mortality, functional ability, quality of life and incurs costs. The primary objective of this study was to estimate the costs of stroke care in Sweden by level of disability and stroke type (ischemic (IS) or hemorrhagic stroke (ICH)). Method Resource use during first and second year following a stroke was estimated based on a research database containing linked data from several registries. Costs were estimated for the acute and post-acute management of stroke, including direct (health care consumption and municipal services) and indirect (productivity losses) costs. Resources and costs were estimated per stroke type and functional disability categorised by Modified Rankin Scale (mRS). Results The results indicated that the average costs per patient following a stroke were 350,000SEK/€37,000–480,000SEK/€50,000, dependent on stroke type and whether it was the first or second year post stroke. Large variations were identified between different subgroups of functional disability and stroke type, ranging from annual costs of 100,000SEK/€10,000–1,100,000SEK/€120,000 per patient, with higher costs for patients with ICH compared to IS and increasing costs with more severe functional disability. Conclusion Functional outcome is a major determinant on costs of stroke care. The stroke type associated with worse outcome (ICH) was also consistently associated to higher costs. Measures to improve function are not only important to individual patients and their family but may also decrease the societal burden of stroke. PMID:28384164

Challenges in building interpersonal care in organized hospital stroke units: The perspectives of stroke survivors, family caregivers and the multidisciplinary team.

PubMed

Ryan, Tony; Harrison, Madeleine; Gardiner, Clare; Jones, Amanda

2017-10-01

To explore the organized stroke unit experience from the multiple perspectives of stroke survivor, family carer and the multi-disciplinary team. Organized stroke unit care reduces morbidity, mortality and institutionalization and is promoted globally as the most effective form of acute and postacute provision. Little research has focused on how care is experienced in this setting from the perspectives of those who receive and provide care. This study used a qualitative approach, employing Framework Analysis. This methodology allows for a flexible approach to data collection and a comprehensive and systematic method of analysis. Semi-structured interviews were undertaken during 2011 and 2012 with former stroke unit stroke survivors, family carers and senior stroke physicians. In addition, eight focus groups were conducted with members of the multi-disciplinary team. One hundred and twenty-five participants were recruited. Three key themes were identified across all data sets. First, two important processes are described: responses to the impact of stroke and seeking information and stroke-specific knowledge. These are underpinned by a third theme: the challenge in building relationships in organized stroke unit care. Stroke unit care provides satisfaction for stroke survivors, particularly in relation to highly specialized medical and nursing care and therapy. It is proposed that moves towards organized stroke unit care, particularly with the emphasis on reduction of length of stay and a focus on hyper-acute models, have implications for interpersonal care practices and the sharing of stroke-specific knowledge. © 2017 John Wiley & Sons Ltd.

Image processing system design for microcantilever-based optical readout infrared arrays

NASA Astrophysics Data System (ADS)

Tong, Qiang; Dong, Liquan; Zhao, Yuejin; Gong, Cheng; Liu, Xiaohua; Yu, Xiaomei; Yang, Lei; Liu, Weiyu

2012-12-01

Compared with the traditional infrared imaging technology, the new type of optical-readout uncooled infrared imaging technology based on MEMS has many advantages, such as low cost, small size, producing simple. In addition, the theory proves that the technology's high thermal detection sensitivity. So it has a very broad application prospects in the field of high performance infrared detection. The paper mainly focuses on an image capturing and processing system in the new type of optical-readout uncooled infrared imaging technology based on MEMS. The image capturing and processing system consists of software and hardware. We build our image processing core hardware platform based on TI's high performance DSP chip which is the TMS320DM642, and then design our image capturing board based on the MT9P031. MT9P031 is Micron's company high frame rate, low power consumption CMOS chip. Last we use Intel's company network transceiver devices-LXT971A to design the network output board. The software system is built on the real-time operating system DSP/BIOS. We design our video capture driver program based on TI's class-mini driver and network output program based on the NDK kit for image capturing and processing and transmitting. The experiment shows that the system has the advantages of high capturing resolution and fast processing speed. The speed of the network transmission is up to 100Mbps.

Mushroom plasmonic metamaterial infrared absorbers

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

Ogawa, Shinpei, E-mail: Ogawa.Shimpei@eb.MitsubishiElectric.co.jp; Fujisawa, Daisuke; Hata, Hisatoshi

2015-01-26

There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved bymore » isotropic XeF{sub 2} etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.« less

Optimization of narrow width effect on titanium thermistor in uncooled antenna-coupled terahertz microbolometer

NASA Astrophysics Data System (ADS)

Banerjee, Amit; Satoh, Hiroaki; Elamaran, Durgadevi; Sharma, Yash; Hiromoto, Norihisa; Inokawa, Hiroshi

2018-04-01

Uncooled antenna-coupled terahertz microbolometer arrays are fabricated with a meander-type Ti thermistor, and design widths (DW) = 0.1 and 0.2 µm, considering the design requirement to miniaturize detectors. Each unit device with DW = 0.1 µm of the thermistor has about 4.7 time higher electrical responsivity (132 V/W) than that with DW = 0.2 µm (28.2 V/W) at 10 µA bias current. For DW = 0.2 µm, the calculated noise equivalent power (NEP) was 2.29 × 10‑9 W/\\sqrt{\\text{Hz}} , whereas the minimum NEP of 4.43 × 10‑10 W/\\sqrt{\\text{Hz}} was obtained for DW = 0.1 µm devices, both at 10 µA bias current. The bulk value of temperature coefficient of resistance (TCR) of the Ti thermistor is markedly compromised in low dimensional devices, still in terms of responsivity and NEP, unit devices with Ti thermistor with the lower DW shows better performance. This is because the narrow width effect is minimized owing to higher resistivity for DW = 0.1 than that for DW = 0.2 µm. In this current report, we highlights the optimization of the narrow width effect on TCR of metal interconnects in nanometer dimensions, which to the best of our knowledge is not available at present.

Fast Recognition of BCI-Inefficient Users Using Physiological Features from EEG Signals: A Screening Study of Stroke Patients.

PubMed

Shu, Xiaokang; Chen, Shugeng; Yao, Lin; Sheng, Xinjun; Zhang, Dingguo; Jiang, Ning; Jia, Jie; Zhu, Xiangyang

2018-01-01

Motor imagery (MI) based brain-computer interface (BCI) has been developed as an alternative therapy for stroke rehabilitation. However, experimental evidence demonstrates that a significant portion (10-50%) of subjects are BCI-inefficient users (accuracy less than 70%). Thus, predicting BCI performance prior to clinical BCI usage would facilitate the selection of suitable end-users and improve the efficiency of stroke rehabilitation. In the current study, we proposed two physiological variables, i.e., laterality index (LI) and cortical activation strength (CAS), to predict MI-BCI performance. Twenty-four stroke patients and 10 healthy subjects were recruited for this study. Each subject was required to perform two blocks of left- and right-hand MI tasks. Linear regression analyses were performed between the BCI accuracies and two physiological predictors. Here, the predictors were calculated from the electroencephalography (EEG) signals during paretic hand MI tasks (5 trials; approximately 1 min). LI values exhibited a statistically significant correlation with two-class BCI (left vs. right) performance (r = -0.732, p < 0.001), and CAS values exhibited a statistically significant correlation with brain-switch BCI (task vs. idle) performance ( r = 0.641, p < 0.001). Furthermore, the BCI-inefficient users were successfully recognized with a sensitivity of 88.2% and a specificity of 85.7% in the two-class BCI. The brain-switch BCI achieved a sensitivity of 100.0% and a specificity of 87.5% in the discrimination of BCI-inefficient users. These results demonstrated that the proposed BCI predictors were promising to promote the BCI usage in stroke rehabilitation and contribute to a better understanding of the BCI-inefficiency phenomenon in stroke patients.

Fast Recognition of BCI-Inefficient Users Using Physiological Features from EEG Signals: A Screening Study of Stroke Patients

PubMed Central

Shu, Xiaokang; Chen, Shugeng; Yao, Lin; Sheng, Xinjun; Zhang, Dingguo; Jiang, Ning; Jia, Jie; Zhu, Xiangyang

2018-01-01

Motor imagery (MI) based brain-computer interface (BCI) has been developed as an alternative therapy for stroke rehabilitation. However, experimental evidence demonstrates that a significant portion (10–50%) of subjects are BCI-inefficient users (accuracy less than 70%). Thus, predicting BCI performance prior to clinical BCI usage would facilitate the selection of suitable end-users and improve the efficiency of stroke rehabilitation. In the current study, we proposed two physiological variables, i.e., laterality index (LI) and cortical activation strength (CAS), to predict MI-BCI performance. Twenty-four stroke patients and 10 healthy subjects were recruited for this study. Each subject was required to perform two blocks of left- and right-hand MI tasks. Linear regression analyses were performed between the BCI accuracies and two physiological predictors. Here, the predictors were calculated from the electroencephalography (EEG) signals during paretic hand MI tasks (5 trials; approximately 1 min). LI values exhibited a statistically significant correlation with two-class BCI (left vs. right) performance (r = −0.732, p < 0.001), and CAS values exhibited a statistically significant correlation with brain-switch BCI (task vs. idle) performance (r = 0.641, p < 0.001). Furthermore, the BCI-inefficient users were successfully recognized with a sensitivity of 88.2% and a specificity of 85.7% in the two-class BCI. The brain-switch BCI achieved a sensitivity of 100.0% and a specificity of 87.5% in the discrimination of BCI-inefficient users. These results demonstrated that the proposed BCI predictors were promising to promote the BCI usage in stroke rehabilitation and contribute to a better understanding of the BCI-inefficiency phenomenon in stroke patients. PMID:29515363

Research of Adhesion Bonds Between Gas-Thermal Coating and Pre-Modified Base

NASA Astrophysics Data System (ADS)

Kovalevskaya, Z.; Zaitsev, K.; Klimenov, V.

2016-08-01

Nature of adhesive bonds between gas-thermal nickel alloy coating and carbon steel base was examined using laser profilometry, optical metallography, transmission and scanning electron microscopy. The steel surface was plastically pre-deformed by an ultrasonic tool. Proved that ultrasound pre-treatment modifies the steel surface. Increase of dislocation density and formation of sub micro-structure are base elements of surface modification. While using high-speed gas-flame, plasma and detonation modes of coatings, surface activation occurs and durable adhesion is formed. Ultrasonic pre-treatment of base material is effective when sprayed particles and base material interact through physical-chemical bond formation. Before applying high-speed gas flame and plasma sprayed coatings, authors recommend ultrasonic pretreatment, which creates periodic wavy topography with a stroke of 250 microns on the steel surface. Before applying detonation sprayed coatings, authors recommend ultrasound pretreatment that create modified surface with a uniform micro-topography.

Quantitative measurements of in-cylinder gas composition in a controlled auto-ignition combustion engine

NASA Astrophysics Data System (ADS)

Zhao, H.; Zhang, S.

2008-01-01

One of the most effective means to achieve controlled auto-ignition (CAI) combustion in a gasoline engine is by the residual gas trapping method. The amount of residual gas and mixture composition have significant effects on the subsequent combustion process and engine emissions. In order to obtain quantitative measurements of in-cylinder residual gas concentration and air/fuel ratio, a spontaneous Raman scattering (SRS) system has been developed recently. The optimized optical SRS setups are presented and discussed. The temperature effect on the SRS measurement is considered and a method has been developed to correct for the overestimated values due to the temperature effect. Simultaneous measurements of O2, H2O, CO2 and fuel were obtained throughout the intake, compression, combustion and expansion strokes. It shows that the SRS can provide valuable data on this process in a CAI combustion engine.

Prediabetes is associated with post-stroke cognitive impairment in ischaemic stroke patients.

PubMed

Wang, Qiongzhang; Zhao, Kai; Cai, Yan; Tu, Xinjie; Liu, Yuntao; He, Jincai

2018-05-15

Diabetes mellitus is associated with post-stroke cognitive impairment. To the best of our knowledge, no study has explored the relationship between prediabetes and post-stroke cognitive impairment. The purpose of this study is to explore the association between prediabetes and cognitive impairment in ischaemic stroke patients at 1 month. Two hundred one acute ischaemic stroke patients were consecutively recruited within the first 24 h after admission and were followed up for 1 month. Patients were divided into a diabetes mellitus group, prediabetes group and non-diabetes mellitus group by fasting glucose levels, 2-h postprandial blood glucose levels and glycosylated haemoglobin levels at admission. Cognitive function was evaluated by the Mini-Mental State Examination at 1 month after stroke. The prediabetes group had a higher risk of post-stroke cognitive impairment than the non-diabetes group (35.7% vs. 18.1%, χ 2  = 4.252, P = .039). In logistical analyses, prediabetes was associated with post-stroke cognitive impairment after adjusting for potential confounding factors (odds ratio 3.062, 95% confidence interval 1.130-8.299, P = .028). Our findings show that prediabetes is associated with post-stroke cognitive impairment and may predict its development at 1 month post-stroke. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of two 12-minute culturally targeted films on intent to call 911 for stroke

PubMed Central

Williams, Olajide; DeSorbo, Alexandra; Eimicke, Joseph; Abel-Bey, Amparo; Valdez, Lenfis; Noble, James; Gordillo, Madeleine; Ravenell, Joseph; Ramirez, Mildred; Teresi, Jeanne A.; Jean-Louis, Girardin; Ogedegbe, Gbenga

2016-01-01

Objective: We assessed the behavioral effect of two 12-minute culturally targeted stroke films on immediately calling 911 for suspected stroke among black and Hispanic participants using a quasi-experimental pretest-posttest design. Methods: We enrolled 102 adult churchgoers (60 black and 42 Hispanic) into a single viewing of one of the 2 stroke films—a Gospel musical (English) or Telenovela (Spanish). We measured intent to immediately call 911 using the validated 28-item Stroke Action Test in English and Spanish, along with related variables, before and immediately after the intervention. Data were analyzed using repeated-measures analysis of variance. Results: An increase in intent to call 911 was seen immediately following the single viewing. Higher self-efficacy for calling 911 was associated with intent to call 911 among Hispanic but not black participants. A composite measure of barriers to calling 911 was not associated with intent to call 911 in either group. A significant association was found between higher stroke symptom knowledge and intent to call 911 at baseline, but not immediately following the intervention. No sex associations were found; however, being older was associated with greater intent to call 911. The majority of participants would strongly recommend the films to others. One participant appropriately called 911 for a real-life stroke event. Conclusions: Narrative communication in the form of tailored short films may improve intent to call 911 for stroke among the black and Hispanic population. PMID:27164682

Effect of two 12-minute culturally targeted films on intent to call 911 for stroke.

PubMed

Williams, Olajide; Leighton-Herrmann, Ellyn; DeSorbo, Alexandra; Eimicke, Joseph; Abel-Bey, Amparo; Valdez, Lenfis; Noble, James; Gordillo, Madeleine; Ravenell, Joseph; Ramirez, Mildred; Teresi, Jeanne A; Jean-Louis, Girardin; Ogedegbe, Gbenga

2016-05-24

We assessed the behavioral effect of two 12-minute culturally targeted stroke films on immediately calling 911 for suspected stroke among black and Hispanic participants using a quasi-experimental pretest-posttest design. We enrolled 102 adult churchgoers (60 black and 42 Hispanic) into a single viewing of one of the 2 stroke films-a Gospel musical (English) or Telenovela (Spanish). We measured intent to immediately call 911 using the validated 28-item Stroke Action Test in English and Spanish, along with related variables, before and immediately after the intervention. Data were analyzed using repeated-measures analysis of variance. An increase in intent to call 911 was seen immediately following the single viewing. Higher self-efficacy for calling 911 was associated with intent to call 911 among Hispanic but not black participants. A composite measure of barriers to calling 911 was not associated with intent to call 911 in either group. A significant association was found between higher stroke symptom knowledge and intent to call 911 at baseline, but not immediately following the intervention. No sex associations were found; however, being older was associated with greater intent to call 911. The majority of participants would strongly recommend the films to others. One participant appropriately called 911 for a real-life stroke event. Narrative communication in the form of tailored short films may improve intent to call 911 for stroke among the black and Hispanic population. © 2016 American Academy of Neurology.

Effect of stress hyperglycemia and intensive rehabilitation therapy in non-diabetic hemorrhagic stroke: Korean Stroke Cohort for Functioning and Rehabilitation.

PubMed

Yoon, J A; Kim, D Y; Sohn, M K; Lee, J; Lee, S-G; Lee, Y-S; Han, E Y; Joo, M C; Oh, G-J; Han, J; Lee, S W; Park, M; Chang, W H; Shin, Y-I; Kim, Y-H

2016-11-01

We investigated the effect of stress hyperglycemia on the functional outcomes of non-diabetic hemorrhagic stroke. In addition, we investigated the usefulness of intensive rehabilitation for improving functional outcomes in patients with stress hyperglycemia. Non-diabetic hemorrhagic stroke patients were recruited and divided into two groups: intracerebral hemorrhage (ICH) (n = 165) and subarachnoid hemorrhage (SAH) (n = 156). Each group was divided into non-diabetics with or without stress hyperglycemia. Functional assessments were performed at 7 days and 3, 6 and 12 months after stroke onset. The non-diabetic with stress hyperglycemia groups were again divided into two groups who either received or did not receive intensive rehabilitation treatment. Serial functional outcome was compared between groups. For the ICH group, patients with stress hyperglycemia had worse modified Rankin Scale, National Institutes of Health Stroke Scale, Functional Ambulatory Category and Korean Mini-Mental State Examination scores than patients without stress hyperglycemia. For the SAH group, patients with stress hyperglycemia had worse scores on all functional assessments than patients without stress hyperglycemia at all time-points. After intensive rehabilitation treatment of patients with stress hyperglycemia, the ICH group had better scores on Functional Ambulatory Category and the SAH group had better scores on all functional assessments than patients without intensive rehabilitation treatment. Stress hyperglycemia affects the long-term prognosis of non-diabetic hemorrhagic stroke patients. Among stress hyperglycemia patients, intensive rehabilitation can enhance functional improvement after stroke. © 2016 EAN.

A systematic review of the effectiveness of secondary prevention lifestyle interventions designed to change lifestyle behaviour following stroke.

PubMed

Lawrence, Maggie; Kerr, Susan; McVey, Ms Caroline; Godwin, Jon

Background Each year, approximately 15 million people worldwide have a stroke; of these, five million die and another five million are chronically disabled. Stroke recurs in approximately 25% of patients during the first five years post-stroke; recurrence may result in death, increased disability or institutionalisation. Modifiable risk factors for recurrent stroke have been identified, and may be addressed by means of behavioural health promotion interventions.Objectives This systematic review sought to establish the effectiveness of secondary prevention behavioural interventions, which address one or more modifiable lifestyle risk factors for recurrent stroke i.e. tobacco use, unhealthy diet, physical inactivity and excessive alcohol consumption. Types of participants The review included studies that had recruited adults (aged ≥18 years) who had had a stroke, minor stroke or transient ischaemic attack.Types of intervention The review considered studies that evaluated behavioural lifestyle interventions, designed to address the prevention of recurrent stroke.Types of outcomes Primary outcomes were concerned with lifestyle behaviour change i.e. tobacco use, diet, physical activity and alcohol consumption, and with change in physiological measures e.g. blood pressure, total cholesterol, and Body Mass Index. Secondary outcome measures included psychological outcomes, learning outcomes and incidence of stroke recurrence.Types of studies Experimental and non-experimental quantitative studies were considered.Search strategy In August 2009, we searched All EMB Reviews, AMED, ASSIA, British Nursing Index and Archive, CINAHL, Conference Proceedings Citation Index - Science, ProQuest dissertation and theses, EMBASE, MEDLINE, PsycINFO, and bibliographies of retrieved papers.Methodological quality and data extraction Two review authors independently assessed methodological quality using standardised critical appraisal instruments from the Joanna Briggs Institute Meta Analysis of Statistics Assessment and Review Instrument, and extracted data using a review-specific data extraction form.Data analysis Where possible, results from the review papers were pooled in statistical meta-analysis using bespoke software based on the system used by the Early Breast Cancer Trialists Collaborative Group. Where statistical pooling was not possible, findings are presented in narrative form.Results Three studies, two RCTs and one quasi-experimental study, involving 581 participants (baseline) were included in the review. Two models of service delivery were reported: shared care and nurse-led. Interventions were delivered to groups or in one-to-one consultations.Meta-analyses of the pooled lifestyle data favoured the interventions (2p=0.02; Note: here and throughout, 2p represents the two-tailed probability). In terms of physiological outcomes, the pooled data favoured the interventions (2p=0.05), particularly those aiming to reduce blood pressure and cholesterol levels. The pooled secondary outcomes, including perceived health status and stroke knowledge favoured the interventions (2p<0.00001), however, the test for heterogeneity was also highly significant.Conclusions Stroke secondary prevention lifestyle interventions are effective in terms of affecting positive change in relation to lifestyle behaviours, physiological and secondary outcomes. However, there was insufficient evidence to determine the effect of intervention on incidence of stroke recurrence.Implications for practice Clinicians should implement stroke secondary prevention interventions which address lifestyle behaviours, physiological factors, psychological outcomes and stroke knowledge.Implications for research Further large-scale, well-designed trials are needed to determine the factors that impact on the effectiveness of secondary prevention interventions.

Post-stroke bacteriuria among stroke patients attending a physiotherapy clinic in Ghana: a cross-sectional study

PubMed Central

Donkor, Eric S; Akumwena, Amos; Amoo, Philip K; Owolabi, Mayowa O; Aspelund, Thor; Gudnason, Vilmundur

2016-01-01

Background Infections are known to be a major complication of stroke patients. In this study, we evaluated the risk of community-acquired bacteriuria among stroke patients, the associated factors, and the causative organisms. Methods This was a cross-sectional study involving 70 stroke patients and 83 age- and sex-matched, apparently healthy controls. Urine specimens were collected from all the study subjects and were analyzed by standard microbiological methods. Demographic and clinical information was also collected from the study subjects. For stroke patients, the information collected also included stroke parameters, such as stroke duration, frequency, and subtype. Results Bacteriuria was significantly higher among stroke patients (24.3%, n=17) than among the control group (7.2%, n=6), with a relative risk of 3.36 (confidence interval [CI], 1.40–8.01, P=0.006). Among the control group, all six bacteriuria cases were asymptomatic, whereas the 17 stroke bacteriuria cases comprised 15 cases of asymptomatic bacteriuria and two cases of symptomatic bacteriuria. Female sex (OR, 3.40; CI, 1.12–10.30; P=0.03) and presence of stroke (OR, 0.24; CI, 0.08–0.70; P=0.009) were significantly associated with bacteriuria. The etiology of bacteriuria was similar in both study groups, and coagulase-negative Staphylococcus spp. were the most predominant organisms isolated from both stroke patients (12.9%) and the control group (2.4%). Conclusion Stroke patients in the study region have a significantly higher risk of community-acquired bacteriuria, which in most cases is asymptomatic. Community-acquired bacteriuria in stroke patients appears to have little or no relationship with clinical parameters of stroke such as stroke subtype, duration and frequency. PMID:27051289

Exploratory study on the methodology of fast imaging of unilateral stroke lesions by electrical impedance asymmetry in human heads.

PubMed

Ma, Jieshi; Xu, Canhua; Dai, Meng; You, Fusheng; Shi, Xuetao; Dong, Xiuzhen; Fu, Feng

2014-01-01

Stroke has a high mortality and disability rate and should be rapidly diagnosed to improve prognosis. Diagnosing stroke is not a problem for hospitals with CT, MRI, and other imaging devices but is difficult for community hospitals without these devices. Based on the mechanism that the electrical impedance of the two hemispheres of a normal human head is basically symmetrical and a stroke can alter this symmetry, a fast electrical impedance imaging method called symmetrical electrical impedance tomography (SEIT) is proposed. In this technique, electrical impedance tomography (EIT) data measured from the undamaged craniocerebral hemisphere (CCH) is regarded as reference data for the remaining EIT data measured from the other CCH for difference imaging to identify the differences in resistivity distribution between the two CCHs. The results of SEIT imaging based on simulation data from the 2D human head finite element model and that from the physical phantom of human head verified this method in detection of unilateral stroke.

Exploratory Study on the Methodology of Fast Imaging of Unilateral Stroke Lesions by Electrical Impedance Asymmetry in Human Heads

PubMed Central

Xu, Canhua; Dai, Meng; You, Fusheng; Shi, Xuetao

2014-01-01

Stroke has a high mortality and disability rate and should be rapidly diagnosed to improve prognosis. Diagnosing stroke is not a problem for hospitals with CT, MRI, and other imaging devices but is difficult for community hospitals without these devices. Based on the mechanism that the electrical impedance of the two hemispheres of a normal human head is basically symmetrical and a stroke can alter this symmetry, a fast electrical impedance imaging method called symmetrical electrical impedance tomography (SEIT) is proposed. In this technique, electrical impedance tomography (EIT) data measured from the undamaged craniocerebral hemisphere (CCH) is regarded as reference data for the remaining EIT data measured from the other CCH for difference imaging to identify the differences in resistivity distribution between the two CCHs. The results of SEIT imaging based on simulation data from the 2D human head finite element model and that from the physical phantom of human head verified this method in detection of unilateral stroke. PMID:25006594

Estrogen-IGF-1 interactions in neuroprotection: Ischemic Stroke as a case study

PubMed Central

Sohrabji, Farida

2014-01-01

The steroid hormone 17b-estradiol and the peptide hormone insulin-like growth factor (IGF)-1 independently exert neuroprotective actions in neurologic diseases such as stroke. Only a few studies have directly addressed the interaction between the two hormone systems, however, there is a large literature that indicates potentially greater interactions between the 17b-estradiol and IGF-1 systems. The present review focuses on key issues related to this interaction including IGF-1 and sex differences and common activation of second messenger systems. Using ischemic stroke as a case study, this review also focuses on independent and cooperative actions of estrogen and IGF-1 on neuroprotection, blood brain barrier integrity, angiogenesis, inflammation and post-stroke epilepsy. Finally, the review also focuses on the astrocyte, a key mediator of post stroke repair, as a local source of 17b-estradiol and IGF-1. This review thus highlights areas where significant new research is needed to clarify the interactions between these two neuroprotectants. PMID:24882635

The principal motions involved in the coupling mechanism of the recovery stroke of the myosin motor

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

Mesentean, Sidonia; Koppole, Sampath; Smith, Jeremy C

2006-12-01

Muscle contraction is driven by a cycle of conformational changes in the myosin II head. After myosin binds ATP and releases from the actin fibril, myosin prepares for the next power stroke by rotating back the converter domain that carries the lever arm by {approx}60 degrees. This recovery stroke is coupled to the activation of myosin's ATPase by a mechanism that is essential for an efficient motor cycle. The mechanics of this coupling have been proposed to occur via two distinct and successive motions of the two helices that hold the converter domain: in a first phase a see-saw motionmore » of the relay helix, followed by a piston/seesaw motion of the SH1 helix in a second phase. To test this model, we have determined the principal motions of these structural elements during equilibrium molecular dynamics simulations of the crystallographic end states of the recovery stroke by using Principal Component Analysis. This reveals that the only principal motions of these two helices that make a large amplitude contribution towards the conformational change of the recovery stroke are indeed the predicted seesaw and piston motions.« less

What's new in stroke? The top 10 studies of 2009-2011: part II.

PubMed

Hart, Robert G; Oczkowski, Wiesław J

2011-06-01

Five studies published between 2009 and 2011 are reviewed that importantly inform stroke prevention for patients with atrial fibrillation (AF) or with cervical carotid artery stenosis. Two large, phase III randomized trials tested novel oral anticoagulants for stroke prevention in patients with AF: the direct thrombin inhibitor dabigatran 150 mg twice daily was superior to adjusted-dose warfarin (RE-LY trial) and the direct factor Xa inhibitor apixaban was far superior to aspirin in patients deemed unsuitable for warfarin (AVERROES trial). For both novel anticoagulants, major bleeding rates were similar to the comparator treatment. Clopidogrel plus aspirin was more efficacious than aspirin alone for prevention of stroke in patients with AF deemed unsuitable for warfarin, but major bleeding was significantly increased with dual antiplatelet therapy (ACTIVE A trial). Two large randomized trials (CREST, ICSS) provide the best available data on the short-term risks of carotid artery stenting vs. endarterectomy. In both trials, periprocedural stroke was more frequent with stenting than with endarterectomy, but the increased risk was largely confined to patients >70 years old. For younger patients, periprocedural risks were comparable with stenting or endarterectomy, but long-term outcomes are required to assess the relative merits of the two procedures.

Early stages of the recovery stroke in myosin II studied by molecular dynamics simulations

PubMed Central

Baumketner, Andrij; Nesmelov, Yuri

2011-01-01

The recovery stroke is a key step in the functional cycle of muscle motor protein myosin, during which pre-recovery conformation of the protein is changed into the active post-recovery conformation, ready to exersice force. We study the microscopic details of this transition using molecular dynamics simulations of atomistic models in implicit and explicit solvent. In more than 2 μs of aggregate simulation time, we uncover evidence that the recovery stroke is a two-step process consisting of two stages separated by a time delay. In our simulations, we directly observe the first stage at which switch II loop closes in the presence of adenosine triphosphate at the nucleotide binding site. The resulting configuration of the nucleotide binding site is identical to that detected experimentally. Distribution of inter-residue distances measured in the force generating region of myosin is in good agreement with the experimental data. The second stage of the recovery stroke structural transition, rotation of the converter domain, was not observed in our simulations. Apparently it occurs on a longer time scale. We suggest that the two parts of the recovery stroke need to be studied using separate computational models. PMID:21922589

Self-latching eccentric cam for dual stroke compressor or pump

DOEpatents

Sisk, Francis J.

1985-01-01

For a dual capacity refrigerant compressor of the type which has an eccentric cam rotatable on a crankpin between two opposite positions which changes the total eccentricity of the crankpin and cam so as to obtain two different stroke lengths, the rotation of the cam on the crankpin being effected by a reversal of motor operation, the cam moves through an angle of about 270.degree. around the crankpin so that a centrifugal force torque tending to hold the cam in place is available at least in the reduced stroke length position of the cam, and by providing lightening cavities and eccentric weightings, the center of mass 74 of the cam can be shifted to obtain the centrifugal torque in the proper direction at both the maximum and reduced stroke positions.

Self-latching eccentric cam for dual stroke compressor or pump

DOEpatents

Sisk, F.J.

1985-01-22

For a dual capacity refrigerant compressor of the type which has an eccentric cam rotatable on a crankpin between two opposite positions which changes the total eccentricity of the crankpin and cam so as to obtain two different stroke lengths, the rotation of the cam on the crankpin being effected by a reversal of motor operation, the cam moves through an angle of about 270[degree] around the crankpin so that a centrifugal force torque tending to hold the cam in place is available at least in the reduced stroke length position of the cam, and by providing lightening cavities and eccentric weightings, the center of mass of the cam can be shifted to obtain the centrifugal torque in the proper direction at both the maximum and reduced stroke positions. 7 figs.

Enhanced electrohydrodynamic force generation in a two-stroke cycle dielectric-barrier-discharge plasma actuator

NASA Astrophysics Data System (ADS)

Sato, Shintaro; Takahashi, Masayuki; Ohnishi, Naofumi

2017-05-01

An approach for electrohydrodynamic (EHD) force production is proposed with a focus on a charge cycle on a dielectric surface. The cycle, consisting of positive-charging and neutralizing strokes, is completely different from the conventional methodology, which involves a negative-charging stroke, in that the dielectric surface charge is constantly positive. The two-stroke charge cycle is realized by applying a DC voltage combined with repetitive pulses. Simulation results indicate that the negative pulse eliminates the surface charge accumulated during constant voltage phase, resulting in repetitive EHD force generation. The time-averaged EHD force increases almost linearly with increasing repetitive pulse frequency and becomes one order of magnitude larger than that driven by the sinusoidal voltage, which has the same peak-to-peak voltage.

Knowledge of stroke among stroke patients and their relatives in Northwest India.

PubMed

Pandian, Jeyaraj Durai; Kalra, Guneet; Jaison, Ashish; Deepak, Sukhbinder Singh; Shamsher, Shivali; Singh, Yashpal; Abraham, George

2006-06-01

The knowledge of warning symptoms and risk factors for stroke has not been studied among patients with stroke in developing countries. We aimed to assess the knowledge of stroke among patients with stroke and their relatives. Prospective tertiary referral hospital-based study in Northwest India. Trained nurses and medical interns interviewed patients with stroke and transient ischemic attack and their relatives about their knowledge of stroke symptoms and risk factors. Univariable and multivariable logistic regression were used. Of the 147 subjects interviewed, 102 (69%) were patients and 45 (31%) were relatives. There were 99 (67%) men and 48 (33%) women and the mean age was 59.7+/-14.1 years. Sixty-two percent of respondents recognized paralysis of one side as a warning symptom and 54% recognized hypertension as a risk factor for stroke. In the multivariable logistic regression analysis, higher education was associated with the knowledge of correct organ involvement in stroke (OR 2.6, CI 1.1- 6.1, P =0.02), whereas younger age (OR 2.7, CI 1.1-7.0, P =0.04) and higher education (OR 4.1, CI 1.5-10.9, P =0.005) correlated with a better knowledge regarding warning symptoms of stroke. In this study cohort, in general, there is lack of awareness of major warning symptoms, risk factors, organ involvement and self-recognition of stroke. However younger age and education status were associated with better knowledge. There is an urgent need for awareness programs about stroke in this study cohort.

The Use of Motion Tracking Technologies in Serious Games to Enhance Rehabilitation in Stroke Patients

ERIC Educational Resources Information Center

Burton, Andrew M.; Liu, Hao; Battersby, Steven; Brown, David; Sherkat, Nasser; Standen, Penny; Walker, Marion

2011-01-01

Stroke is the main cause of long term disability worldwide. Of those surviving, more than half will fail to regain functional usage of their impaired upper limb. Typically stroke upper limb rehabilitation exercises consist of repeated movements, which when tracked can form the basis of inputs to games. This paper discusses two systems utilizing…

Associations and Dissociations of Transitive and Intransitive Gestures in Left and Right Hemisphere Stroke Patients

ERIC Educational Resources Information Center

Stamenova, Vessela; Roy, Eric A.; Black, Sandra E.

2010-01-01

The study investigated performance on pantomime and imitation of transitive and intransitive gestures in 80 stroke patients, 42 with left (LHD) and 38 with right (RHD) hemisphere damage. Patients were also categorized in two groups based on the time that has elapsed between their stroke and the apraxia assessment: acute-subacute (n = 42) and…

Inter-rater reliability of the Sødring Motor Evaluation of Stroke patients (SMES).

PubMed

Halsaa, K E; Sødring, K M; Bjelland, E; Finsrud, K; Bautz-Holter, E

1999-12-01

The Sødring Motor Evaluation of Stroke patients is an instrument for physiotherapists to evaluate motor function and activities in stroke patients. The rating reflects quality as well as quantity of the patient's unassisted performance within three domains: leg, arm and gross function. The inter-rater reliability of the method was studied in a sample of 30 patients admitted to a stroke rehabilitation unit. Three therapists were involved in the study; two therapists assessed the same patient on two consecutive days in a balanced design. Cohen's weighted kappa and McNemar's test of symmetry were used as measures of item reliability, and the intraclass correlation coefficient was used to express the reliability of the sumscores. For 24 out of 32 items the weighted kappa statistic was excellent (0.75-0.98), while 7 items had a kappa statistic within the range 0.53-0.74 (fair to good). The reliability of one item was poor (0.13). The intraclass correlation coefficient for the three sumscores was 0.97, 0.91 and 0.97. We conclude that the Sødring Motor Evaluation of Stroke patients is a reliable measure of motor function in stroke patients undergoing rehabilitation.

Patient knowledge on stroke risk factors, symptoms and treatment options.

PubMed

Faiz, Kashif Waqar; Sundseth, Antje; Thommessen, Bente; Rønning, Ole Morten

2018-01-01

Public campaigns focus primarily on stroke symptom and risk factor knowledge, but patients who correctly recognize stroke symptoms do not necessarily know the reason for urgent hospitalization. The aim of this study was to explore knowledge on stroke risk factors, symptoms and treatment options among acute stroke and transient ischemic attack patients. This prospective study included patients admitted to the stroke unit at the Department of Neurology, Akershus University Hospital, Norway. Patients with previous cerebrovascular disease, patients receiving thrombolytic treatment and patients who were not able to answer the questions in the questionnaire were excluded. Patients were asked two closed-ended questions: "Do you believe that stroke is a serious disorder?" and "Do you believe that time is of importance for stroke treatment?". In addition, patients were asked three open-ended questions where they were asked to list as many stroke risk factors, stroke symptoms and stroke treatment options as they could. A total of 173 patients were included, of whom 158 (91.3%) confirmed that they regarded stroke as a serious disorder and 148 patients (85.5%) considered time being of importance. In all, 102 patients (59.0%) could not name any treatment option. Forty-one patients (23.7%) named one or more adequate treatment options, and they were younger ( p <0.001) and had higher educational level ( p <0.001), but had a nonsignificant shorter prehospital delay time ( p =0.292). The level of stroke treatment knowledge in stroke patients seems to be poor. Public campaigns should probably also focus on information on treatment options, which may contribute to reduce prehospital delay and onset-to-treatment-time.

Factors associated with community reintegration in the first year after stroke: a qualitative meta-synthesis.

PubMed

Walsh, Mary E; Galvin, Rose; Loughnane, Cliona; Macey, Chris; Horgan, N Frances

2015-01-01

Although acute stroke care has improved survival, many individuals report dissatisfaction with community reintegration after stroke. The aim of this qualitative meta-synthesis was to examine the barriers and facilitators of community reintegration in the first year after stroke from the perspective of people with stroke. A systematic literature search was conducted. Papers that used qualitative methods to explore the experiences of individuals with stroke around community reintegration in the first year after stroke were included. Two reviewers independently assessed the methodological quality of papers. Themes, concepts and interpretations were extracted from each study, compared and meta-synthesised. From the 18 included qualitative studies four themes related to community reintegration in the first year after stroke were identified: (i) the primary effects of stroke, (ii) personal factors, (iii) social factors and (iv) relationships with professionals. This review suggests that an individual's perseverance, adaptability and ability to overcome emotional challenges can facilitate reintegration into the community despite persisting effects of their stroke. Appropriate support from family, friends, the broader community and healthcare professionals is important. Therapeutic activities should relate to meaningful activities and should be tailored to the individual stroke survivor. Stroke survivors feel that rehabilitation in familiar environments and therapeutic activities that reflect real-life could help their community re-integration. In addition to the physical sequelae of stroke, emotional consequences of stroke should be addressed during rehabilitation. Healthcare professionals can provide clear and locally relevant advice to facilitate aspects of community reintegration, including the return to driving and work.

A leader-return-stroke consistent macroscopic model for calculations of return stroke current and its optical and electromagnetic emissions

NASA Astrophysics Data System (ADS)

Cai, Shuyao; Chen, Mingli; Du, Yaping; Qin, Zilong

2017-08-01

A downward lightning flash usually starts with a downward leader and an upward connecting leader followed by an upward return stroke. It is the preceding leader that governs the following return stroke property. Besides, the return stroke property evolves with height and time. These two aspects, however, are not well addressed in most existing return stroke models. In this paper, we present a leader-return stroke consistent model based on the time domain electric field integral equation, which is a growth and modification of Kumar's macroscopic model. The model is further extended to simulate the optical and electromagnetic emissions of a return stroke by introducing a set of equations relating the return stroke current and conductance to the optical and electromagnetic emissions. With a presumed leader initiation potential, the model can then simulate the temporal and spatial evolution of the current, charge transfer, channel size, and conductance of the return stroke, furthermore the optical and electromagnetic emissions. The model is tested with different leader initiation potentials ranging from -10 to -140 MV, resulting in different return stroke current peaks ranging from 2.6 to 209 kA with different return stroke speed peaks ranging from 0.2 to 0.8 speed of light and different optical power peaks ranging from 4.76 to 248 MW/m. The larger of the leader initiation potential, the larger of the return stroke current and speed. Both the return stroke current and speed attenuate exponentially as it propagates upward. All these results are qualitatively consistent with those reported in the literature.

The Alberta Stroke Prevention in TIAs and mild strokes (ASPIRE) intervention: rationale and design for evaluating the implementation of a province-wide TIA triaging system.

PubMed

Jeerakathil, Thomas; Shuaib, Ashfaq; Majumdar, Sumit R; Demchuk, Andrew M; Butcher, Kenneth S; Watson, Tim J; Dean, Naeem; Gordon, Deb; Edmond, Cathy; Coutts, Shelagh B

2014-10-01

Stroke risk after transient ischaemic attack is high and, it is a challenge worldwide to provide urgent assessment and preventive services to entire populations. To determine whether a province-wide transient ischaemic attack Triaging algorithm and transient ischaemic attack hotline (the Alberta Stroke Prevention in transient ischaemic attacks and mild strokes intervention) can reduce the rate of stroke recurrence following transient ischaemic attack across the population of Alberta, Canada (population 3·7 million, 90-day rate of post-stroke transient ischaemic attack currently 9·5%). It also seeks to improve upon current transient ischaemic attack triaging rules by incorporating time from symptom onset as a predictive variable. The transient ischaemic attack algorithm and hotline were developed with a broad consensus of clinicians, patients, policy-makers, and researchers and based on local adaptation of the work of others and research and insights developed within the province. Because neither patient-level nor region-level randomization was possible, we conducted a quasi-experimental design examining changes in the post-transient ischaemic attack rate of stroke recurrence before and after the 15-month implementation period using an interrupted time-series regression analysis. The design controls for changes in case-mix, co-interventions, and secular trends. A prospective transient ischaemic attack cohort will also be concurrently created with telephone follow-up at seven-days and 90 days as well as passive follow-up over the longer term using linkages to provincial healthcare administrative databases. The primary outcome measure is the change in recurrence rate of stroke following transient ischaemic attack at seven-days and 90 days, comparing a period of two-years before vs. two-years after the intervention is implemented. All cases of recurrent stroke will be validated. Secondary outcomes include functional status, hospitalizations, morbidity, and mortality. We are undertaking a rigorous evaluation of a population-based approach to improving quality of transient ischaemic attack care. Whether positive or negative, our work should provide important insights for all potential stakeholders. © 2012 The Authors. International Journal of Stroke © 2012 World Stroke Organization.

Blood-pressure targets in patients with recent lacunar stroke: the SPS3 randomised trial.

PubMed

Benavente, O R; Coffey, C S; Conwit, R; Hart, R G; McClure, L A; Pearce, L A; Pergola, P E; Szychowski, J M

2013-08-10

Lowering of blood pressure prevents stroke but optimum target levels to prevent recurrent stroke are unknown. We investigated the effects of different blood-pressure targets on the rate of recurrent stroke in patients with recent lacunar stroke. In this randomised open-label trial, eligible patients lived in North America, Latin America, and Spain and had recent, MRI-defined symptomatic lacunar infarctions. Patients were recruited between March, 2003, and April, 2011, and randomly assigned, according to a two-by-two multifactorial design, to a systolic-blood-pressure target of 130-149 mm Hg or less than 130 mm Hg. The primary endpoint was reduction in all stroke (including ischaemic strokes and intracranial haemorrhages). Analysis was done by intention to treat. This study is registered with ClinicalTrials.gov, number NCT 00059306. 3020 enrolled patients, 1519 in the higher-target group and 1501 in the lower-target group, were followed up for a mean of 3·7 (SD 2·0) years. Mean age was 63 (SD 11) years. After 1 year, mean systolic blood pressure was 138 mm Hg (95% CI 137-139) in the higher-target group and 127 mm Hg (95% CI 126-128) in the lower-target group. Non-significant rate reductions were seen for all stroke (hazard ratio 0·81, 95% CI 0·64-1·03, p=0·08), disabling or fatal stroke (0·81, 0·53-1·23, p=0·32), and the composite outcome of myocardial infarction or vascular death (0·84, 0·68-1·04, p=0·32) with the lower target. The rate of intracerebral haemorrhage was reduced significantly (0·37, 0·15-0·95, p=0·03). Treatment-related serious adverse events were infrequent. Although the reduction in stroke was not significant, our results support that in patients with recent lacunar stroke, the use of a systolic-blood-pressure target of less than 130 mm Hg is likely to be beneficial. National Institutes of Health-National Institute of Neurological Disorders and Stroke (NIH-NINDS). Copyright © 2013 Elsevier Ltd. All rights reserved.

Embolic Strokes of Undetermined Source in the Athens Stroke Registry: An Outcome Analysis.

PubMed

Ntaios, George; Papavasileiou, Vasileios; Milionis, Haralampos; Makaritsis, Konstantinos; Vemmou, Anastasia; Koroboki, Eleni; Manios, Efstathios; Spengos, Konstantinos; Michel, Patrik; Vemmos, Konstantinos

2015-08-01

Information about outcomes in Embolic Stroke of Undetermined Source (ESUS) patients is unavailable. This study provides a detailed analysis of outcomes of a large ESUS population. Data set was derived from the Athens Stroke Registry. ESUS was defined according to the Cryptogenic Stroke/ESUS International Working Group criteria. End points were mortality, stroke recurrence, functional outcome, and a composite cardiovascular end point comprising recurrent stroke, myocardial infarction, aortic aneurysm rupture, systemic embolism, or sudden cardiac death. We performed Kaplan-Meier analyses to estimate cumulative probabilities of outcomes by stroke type and Cox-regression to investigate whether stroke type was outcome predictor. 2731 patients were followed-up for a mean of 30.5±24.1months. There were 73 (26.5%) deaths, 60 (21.8%) recurrences, and 78 (28.4%) composite cardiovascular end points in the 275 ESUS patients. The cumulative probability of survival in ESUS was 65.6% (95% confidence intervals [CI], 58.9%-72.2%), significantly higher compared with cardioembolic stroke (38.8%, 95% CI, 34.9%-42.7%). The cumulative probability of stroke recurrence in ESUS was 29.0% (95% CI, 22.3%-35.7%), similar to cardioembolic strokes (26.8%, 95% CI, 22.1%-31.5%), but significantly higher compared with all types of noncardioembolic stroke. One hundred seventy-two (62.5%) ESUS patients had favorable functional outcome compared with 280 (32.2%) in cardioembolic and 303 (60.9%) in large-artery atherosclerotic. ESUS patients had similar risk of composite cardiovascular end point as all other stroke types, with the exception of lacunar strokes, which had significantly lower risk (adjusted hazard ratio, 0.70 [95% CI, 0.52-0.94]). Long-term mortality risk in ESUS is lower compared with cardioembolic strokes, despite similar rates of recurrence and composite cardiovascular end point. Recurrent stroke risk is higher in ESUS than in noncardioembolic strokes. © 2015 American Heart Association, Inc.

40 CFR 205.155 - Motorcycle class and manufacturer abbreviation.

Code of Federal Regulations, 2014 CFR

2014-07-01

... separate combinations of the following parameters: (1) Engine type: (i) Gasoline—two stroke. (ii) Gasoline—four stroke. (iii) Gasoline—rotary. (iv) Other. (2) Engine displacement. (3) Engine configuration: (i...

40 CFR 205.155 - Motorcycle class and manufacturer abbreviation.

Code of Federal Regulations, 2012 CFR

2012-07-01

... separate combinations of the following parameters: (1) Engine type: (i) Gasoline—two stroke. (ii) Gasoline—four stroke. (iii) Gasoline—rotary. (iv) Other. (2) Engine displacement. (3) Engine configuration: (i...

40 CFR 205.155 - Motorcycle class and manufacturer abbreviation.

Code of Federal Regulations, 2013 CFR

2013-07-01

... separate combinations of the following parameters: (1) Engine type: (i) Gasoline—two stroke. (ii) Gasoline—four stroke. (iii) Gasoline—rotary. (iv) Other. (2) Engine displacement. (3) Engine configuration: (i...

40 CFR 205.155 - Motorcycle class and manufacturer abbreviation.

Code of Federal Regulations, 2010 CFR

2010-07-01

... separate combinations of the following parameters: (1) Engine type: (i) Gasoline—two stroke. (ii) Gasoline—four stroke. (iii) Gasoline—rotary. (iv) Other. (2) Engine displacement. (3) Engine configuration: (i...

40 CFR 205.155 - Motorcycle class and manufacturer abbreviation.

Code of Federal Regulations, 2011 CFR

2011-07-01

... separate combinations of the following parameters: (1) Engine type: (i) Gasoline—two stroke. (ii) Gasoline—four stroke. (iii) Gasoline—rotary. (iv) Other. (2) Engine displacement. (3) Engine configuration: (i...

Side branch absorber for exhaust manifold of two-stroke internal combustion engine

DOEpatents

Harris, Ralph E [San Antonio, TX; Broerman, III, Eugene L.; Bourn, Gary D [Laramie, WY

2011-01-11

A method of improving scavenging operation of a two-stroke internal combustion engine. The exhaust pressure of the engine is analyzed to determine if there is a pulsation frequency. Acoustic modeling is used to design an absorber. An appropriately designed side branch absorber may be attached to the exhaust manifold.

Fluent Aphasia in Telugu: A Case Comparison Study of Semantic Dementia and Stroke Aphasia

ERIC Educational Resources Information Center

Alladi, Suvarna; Mridula, Rukmini; Mekala, Shailaja; Rupela, Vani; Kaul, Subhash

2010-01-01

This study presents two cases with fluent aphasia in Telugu with semantic dementia and post-stroke fluent aphasia. Comparable scores were obtained on the conventional neuropsychological and language tests that were administered on the two cases. Both cases demonstrated fluent, grammatical and well-articulated speech with little content, impaired…

A critical velocity of squeezing a droplet through a circular constriction: implications on ischemic stroke

NASA Astrophysics Data System (ADS)

Zhang, Zhifeng; Drapaca, Corina

2016-11-01

Ischemic stroke accounts for about 87 percent of all stroke cases. In these cases, models of squeezing a droplet through a smaller constriction channel can help better understand the pathology and capillary restoring after a Stroke. In the present research, we analytical expressed the minimum impulse of squeezing a droplet through a circular channel as well as its critical velocity. By comparison with a previously defined critical velocity, we find the difference between these two. Applications of this research in the understanding of ischemic stroke are also discussed. Zhifeng Zhang thanks the support of Robert A. Sebrosky Graduate Fellowship in Engineering Science and Mechanics, the Pennsylvania State University.

Cupping for stroke rehabilitation: a systematic review.

PubMed

Lee, Myeong Soo; Choi, Tae-Young; Shin, Byung-Cheul; Han, Chang-ho; Ernst, Edzard

2010-07-15

Cupping is often used for stroke rehabilitation in Asian countries. Currently, no systematic review of this topic is available. The aim of this systematic review is to summarize and critically evaluate the evidence for and against the effectiveness of cupping for stroke rehabilitation. Thirteen databases were searched from their inception through March of 2010 without language restrictions. Prospective clinical trials were included if cupping was tested as the sole treatment or as an adjunct to other conventional treatments for stroke rehabilitation. We found 43 potentially relevant articles, of which 5 studies including 3 randomized clinical trials (RCTs) and 2 uncontrolled observational studies (UOSs) met our inclusion criteria. Cupping was compared with acupuncture, electro-acupuncture and warm needling. Some superior effects of cupping were found in two of the RCTs when compared to acupuncture in hemiplegic shoulder pain and high upper-limb myodynamia after stroke. The other RCT failed to show favorable effects of cupping when compared to acupuncture and warm needling in patients with hemiplegic hand edema. The two UOSs reported favorable effects of cupping on aphasia and intractable hiccup after stroke. There are not enough trials to provide evidence for the effectiveness of cupping for stroke rehabilitation because most of the included trials compared the effects with unproven evidence and were not informative. Future RCTs seem warranted but must overcome the methodological shortcomings of the existing evidence. Copyright 2010 Elsevier B.V. All rights reserved.

Intravenous thrombolysis guided by a telemedicine consultation system for acute ischaemic stroke patients in China: the protocol of a multicentre historically controlled study

PubMed Central

Yuan, Ziwen; Wang, Bo; Li, Feijiang; Wang, Jing; Zhi, Jin; Luo, Erping; Liu, Zhirong; Zhao, Gang

2015-01-01

Introduction The rate of intravenous thrombolysis with tissue-type plasminogen activator or urokinase for stroke patients is extremely low in China. It has been demonstrated that a telestroke service may help to increase the rate of intravenous thrombolysis and improve stroke care quality in local hospitals. The aim of this study, also called the Acute Stroke Advancing Program, is to evaluate the effectiveness and safety of decision-making concerning intravenous thrombolysis via a telemedicine consultation system for acute ischaemic stroke patients in China. Methods and analysis This is a multicentre historically controlled study with a planned enrolment of 300 participants in each of two groups. The telestroke network consists of one hub hospital and 14 spoke hospitals in underserved regions of China. The usual stroke care quality in the spoke hospitals without guidance from the hub hospital will be used as the historical control. The telemedicine consultation system is an interactive, two-way, wireless, audiovisual system accessed on portable devices. The primary outcome is the percentage of patients treated with intravenous thrombolysis within 4.5 h of stroke onset. Ethics and dissemination The project has been approved by the Institutional Review Board of Xijing Hospital. The results will be published in scientific journals and presented to local government and relevant institutes. Trial registration number NCT02088346 (12 March 2014). PMID:25979867

UPDATE ON THE GLOBAL BURDEN OF ISCHAEMIC AND HAEMORRHAGIC STROKE IN 1990–2013: THE GBD 2013 STUDY

PubMed Central

Feigin, Valery L.; Krishnamurthi, Rita; Parmar, Priya; Norrving, Bo; Mensah, George A.; Bennett, Derrick A.; Barker-Collo, Suzanne; Moran, Andrew; Sacco, Ralph L.; Truelsen, Thomas; Davis, Stephen; Pandian, Jeyaraj Durai; Naghavi, Mohsen; Forouzanfar, Mohammad H.; Nguyen, Grant; Johnson, Catherine O.; Vos, Theo; Meretoja, Atte; Murray, Christopher; Roth, Gregory A.; Thrift, Amanda; Banerjee, Amitava; Kengne, Andre Pascal; Misganaw, Awoke; Kissela, Brett M.; Wolfe, Charles; Yu, Chuanhua; Anderson, Craig; Kim, Daniel; Rojas-Rueda, David; Tanne, David; Tirschwell, David Lawrence; Nand, Devina; Kazi, Dhruv S.; Pourmalek, Farshad; Catalá-López, Ferrán; Abd-Allah, Foad; Gankpé, Fortuné; deVeber, Gabrielle; Donnan, Geoffrey; Hankey, Graeme J.; Christensen, Hanne K.; Campos-Nonato, Ismael; Shiue, Ivy; Fernandes, Jefferson G.; Jonas, Jost B.; Sheth, Kevin; Kim, Yunjin; Dokova, Klara; Stroumpoulis, Konstantinos; Sposato, Luciano A.; Bahit, Maria Cecilia; Geleijnse, Johanna M.; Mackay, Mark T.; Mehndiratta, Man Mohan; Endres, Matthias; Giroud, Maurice; Brainin, Michael; Kravchenko, Michael; Piradov, Michael; Soljak, Michael; Liu, Ming; Connor, Myles; Venketasubramanian, Narayanaswamy; Bornstein, Natan; Shamalov, Nikolay; Roy, Nobhojit; Cabral, Norberto; Beauchamp, Norman J.; Lavados, Pablo M.; Jeemon, Panniyammakal; Lotufo, Paulo A.; Chowdhury, Rajiv; Sahathevan, Ramesh; Hamadeh, Randah R.; Malekzadeh, Reza; Gillium, Richard; Westerman, Ronny; Akinyemi, Rufus Olusola; Salman, Rustam Al-Shahi; Dharmaratne, Samath D.; Basu, Sanjay; Abera, Semaw Ferede; Kosen, Soewarta; Sampson, Uchechukwu K. A.; Caso, Valeria; Vlassov, Vasiliy; Melaku, Yohannes Adama; Kokubo, Yoshiohiro; Shinohara, Yukito; Varakin, Yuri; Wang, Wenzhi

2015-01-01

Background Global stroke epidemiology is changing rapidly. Although age-standardised rates of stroke mortality have decreased worldwide in the past two decades, the absolute numbers of people who have a stroke every year, live with the consequences of stroke, and die from their stroke are increasing. Regular updates on the current level of stroke burden are important for advancing our knowledge on stroke epidemiology and facilitate organization and planning of evidence-based stroke care. Objectives To estimate incidence, prevalence, mortality, disability-adjusted life-years (DALYs) and years lived with disability (YLDs), and their trends for ischaemic stroke (IS) and haemorrhagic stroke (HS) for 188 countries from 1990–2013. Methodology Stroke incidence, prevalence, mortality, DALYs and YLDs were estimated using all available data on mortality and stroke incidence, prevalence and excess mortality. Statistical models and country-level covariate data were employed and all rates were age-standardised to a global population. All estimated were produced with 95% uncertainty intervals (UI). Results In 2013, there were globally almost 25.7 million stroke survivors (71% with IS), 6.5 million deaths from stroke (51% died from IS), 113 million DALYs due to stroke (58% due to IS), and 10.3 million new strokes (67% IS). Over the 1990–2013 period, there was a significant increase in the absolute number of DALYs due to IS, and of deaths from IS and HS, survivors and incident events for both IS and HS. The preponderance of the burden of stroke continued to reside in developing countries, comprising 75.2% of deaths from stroke and 81.0% of stroke-related DALYs. Globally, the proportional contribution of stroke-related DALYs and deaths due to stroke compared to all diseases increased from 1990 (3.54% [95% UI 3.11–4.00%] and 9.66% [95% UI 8.47–10.70%]) to 2013 (4.62% [95% UI 4.01–5.30%] and 11.75% [95% UI 10.45–13.31%], respectively), but there was a diverging trend in developed and developing countries with a significant increase in DALYs and deaths in developing countries, and no measurable change in the proportional contribution of DALYs and deaths from stroke in developed countries. Conclusion Global stroke burden continues to increase globally. More efficient stroke prevention and management strategies are urgently needed to halt and eventually reverse the stroke pandemic, while universal access to organized stroke services should be a priority. PMID:26505981

Impact of living and socioeconomic characteristics on cardiovascular risk in ischemic stroke patients.

PubMed

Amarenco, Pierre; Abboud, Halim; Labreuche, Julien; Arauz, Antonio; Bryer, Alan; Lavados, Pablo M; Massaro, Ayrton; Munoz Collazos, Mario; Steg, Philippe Gabriel; Yamout, Bassem I; Vicaut, Eric

2014-12-01

We aimed to stratify the risk of vascular event recurrence in patients with cerebral infarction according to living and socioeconomic characteristics and geographic region. The Outcomes in Patients with TIA and Cerebrovascular Disease (OPTIC) study is an international prospective study of patients aged 45 years or older who required secondary prevention of stroke [following either an acute transient ischemic attack, minor ischemic strokes, or recent (less than six-months previous), stable, first-ever, nondisabling ischemic stroke]. A total 3635 patients from 245 centers in 17 countries in four regions (Latin America, Middle East, North Africa, South Africa) were enrolled between 2007 and 2008. The outcome measure was the two-year rate of a composite of major vascular events (vascular death, myocardial infarction and stroke). During the two-year follow-up period, 516 patients experienced at least one major cardiovascular event, resulting in an event rate of 15·6% (95% confidence interval 14·4-16·9%). Event rates varied across geographical region (P < 0·001), ranging from 13·0% in Latin America to 20·7% in North Africa. Unemployment status, living in a rural area, not living in fully serviced accommodation (i.e., house or apartment with its own electricity, toilet and water supply), no health insurance coverage, and low educational level (less than two-years of schooling) were predictors of major vascular events. Major vascular event rates steeply increased with the number of low-quality living/socioeconomic conditions (from 13·4% to 47·9%, adjusted P value for trend <0·001). Vascular risk in stroke patients in low- and middle-income countries varies not only with the number of arterial beds involved but also with socioeconomic variables. © 2014 World Stroke Organization.

Implementation of evidence-based stroke care: enablers, barriers, and the role of facilitators

PubMed Central

Purvis, Tara; Moss, Karen; Denisenko, Sonia; Bladin, Chris; Cadilhac, Dominique A

2014-01-01

A stroke care strategy was developed in 2007 to improve stroke services in Victoria, Australia. Eight stroke network facilitators (SNFs) were appointed in selected hospitals to enable the establishment of stroke units, develop thrombolysis services, and implement protocols. We aimed to explain the main issues being faced by clinicians in providing evidence-based stroke care, and to determine if the appointment of an SNF was perceived as an acceptable strategy to improve stroke care. Face-to-face semistructured interviews were used in a qualitative research design. Interview transcripts were verified by respondents prior to coding. Two researchers conducted thematic analysis of major themes and subthemes. Overall, 84 hospital staff participated in 33 interviews during 2008. The common factors found to impact on stroke care included staff and equipment availability, location of care, inconsistent use of clinical pathways, and professional beliefs. Other barriers included limited access to specialist clinicians and workload demands. The establishment of dedicated stroke units was considered essential to improve the quality of care. The SNF role was valued for identifying gaps in care and providing capacity to change clinical processes. This is the first large, qualitative multicenter study to describe issues associated with delivering high-quality stroke care and the potential benefits of SNFs to facilitate these improvements. PMID:25246799

If Time Is Brain Where Is the Improvement in Prehospital Time after Stroke?

PubMed Central

Pulvers, Jeremy N.; Watson, John D. G.

2017-01-01

Despite the availability of thrombolytic and endovascular therapy for acute ischemic stroke, many patients are ineligible due to delayed hospital arrival. The identification of factors related to either early or delayed hospital arrival may reveal potential targets of intervention to reduce prehospital delay and improve access to time-critical thrombolysis and clot retrieval therapy. Here, we have reviewed studies reporting on factors associated with either early or delayed hospital arrival after stroke, together with an analysis of stroke onset to hospital arrival times. Much effort in the stroke treatment community has been devoted to reducing door-to-needle times with encouraging improvements. However, this review has revealed that the median onset-to-door times and the percentage of stroke patients arriving before the logistically critical 3 h have shown little improvement in the past two decades. Major factors affecting prehospital time were related to emergency medical pathways, stroke symptomatology, patient and bystander behavior, patient health characteristics, and stroke treatment awareness. Interventions addressing these factors may prove effective in reducing prehospital delay, allowing prompt diagnosis, which in turn may increase the rates and/or efficacy of acute treatments such as thrombolysis and clot retrieval therapy and thereby improve stroke outcomes. PMID:29209269

Design and experimental investigations on six-stroke SI engine using acetylene with water injection.

PubMed

Gupta, Keshav; Suthar, Kishanlal; Jain, Sheetal Kumar; Agarwal, Ghanshyam Das; Nayyar, Ashish

2018-06-02

In the present study, a four-stroke cycle gasoline engine is redesigned and converted into a six-stroke cycle engine and experimental study has been conducted using gasoline and acetylene as fuel with water injection at the end of the recompression stroke. Acetylene has been used as an alternative fuel along with gasoline and performance of the six-stroke spark ignition (SI) engine with these two fuels has been studied separately and compared. Brake power and thermal efficiency are found to be 5.18 and 1.55% higher with acetylene as compared to gasoline in the six-stroke engine. However, thermal efficiency is found to be 45% higher with acetylene in the six-stroke engine as compared to four-stroke SI engine. The CO and HC emissions were found to be reduced by 13.33 and 0.67% respectively with acetylene as compared to gasoline due to better combustion of acetylene. The NO x emission was reduced by 5.65% with acetylene due to lower peak temperature by water injection. The experimental results showed better engine performance and emissions with acetylene as fuel in the six-stroke engine.

Participation in leisure activities after stroke: A survey of community-residing stroke survivors in Nigeria.

PubMed

Vincent-Onabajo, Grace; Blasu, Cephas

2016-01-01

Leisure provides pleasure and relaxation, and has health benefits even after a stressful and life-changing event such as a stroke. This study examined leisure participation among a sample of community-residing stroke survivors in Nigeria. Fifty-five stroke survivors undergoing rehabilitation were consecutively recruited from two government hospitals in Northern Nigeria. Data on pre- and post-stroke participation, and socio-demographic (age, sex, marital, employment, and educational status) and clinical (level of disability, post-stroke duration, stroke type and side of hemiplegia/hemiparesis) attributes of the stroke survivors were obtained. Leisure participation was assessed in four domains of recreational, social, cognitive, and productive/creative activities. Associations between leisure participation and the socio-demographic and clinical variables were examined using bivariate analysis. Mean (SD) age of the stroke survivors was 53.55 (14.39) years. Prevalence of leisure participation was 89.1%. Participation in specific leisure domains however varied thus: social (83.6%), cognitive (60%), recreational (41.8%), productive/creative activities (30.9%). Significant associations were observed between participation in cognitive, productive/creative, and recreational leisure activities, and specific socio-demographic and clinical attributes. Leisure participation was high in a general sense but marginal in recreational and productive/creative activities. The observed socio-demographic and clinical associations with post-stroke leisure participation may assist in providing effective leisure rehabilitation strategies.

Evaluation of neurogenic dysphagia in Iraqi patients with acute stroke.

PubMed

Hasan, Zeki N; Al-Shimmery, Ehsan K; Taha, Mufeed A

2010-04-01

To clinically assess neurogenic dysphagia, and to correlate its presence with demographic features, different stroke risk factors, anatomical arterial territorial stroke types, and pathological stroke types. Seventy-two stroke inpatients were studied between July 2007 and February 2008, at the Departments of Medicine and Neurology at Al-Yarmouk Teaching Hospital, Baghdad, and Rizgary Teaching Hospital, Erbil, Iraq. All patients were assessed using the Mann Assessment of Swallowing Ability score (MASA), Modified Rankin Scale, and the Stroke Risk Scorecard. All patients were reassessed after one month. There were 40 males and 32 females. Sixty-eight patients had ischemic stroke, and 4 had primary intracerebral hemorrhage (ICH). According to the MASA score, 55% of anterior circulation stroke (ACS) cases were associated with dysphasia, and 91% of lateral medullary syndrome cases were associated with dysphagia. Fifty-six percent of ACS dysphagic cases improved within the first month. Forty percent of dysphagic patients died in the one month follow up period, and in most, death was caused by aspiration pneumonia. We observed no significant differences regarding demographic features of dysphagia. Dysphagia can be an indicator of the severity of stroke causing higher mortality and morbidity in affected patients. It was not related to the stroke risk factors and the type of stroke. It is essential from a prognostic point of view to assess swallowing, and to treat its complications early.

Brunnstrom Recovery Stage and Motricity Index for the Evaluation of Upper Extremity in Stroke: Analysis for Correlation and Responsiveness

ERIC Educational Resources Information Center

Safaz, Ismail; Ylmaz, Bilge; Yasar, Evren; Alaca, Rdvan

2009-01-01

The aim of this study was to find out first whether Brunnstrom recovery stage (BRS) and motricity index (MI) were correlated with each other and second to observe whether the two assessment tools were sensitive to changes regarding the rehabilitation outcome. Forty-six stroke patients who were admitted to the Stroke Rehabilitation Unit at our…

Uncooled infrared photon detector and multicolor infrared detection using microoptomechanical sensors

DOEpatents

Datskos, Panagiotis G.; Rajic, Solobodan; Datskou, Irene C.

1999-01-01

Systems and methods for infrared detection are described. An optomechanical photon detector includes a semiconductor material and is based on measurement of a photoinduced lattice strain. A multicolor infrared sensor includes a stack of frequency specific optomechanical detectors. The stack can include one, or more, of the optomechanical photon detectors that function based on the measurement of photoinduced lattice strain. The systems and methods provide advantages in that rapid, sensitive multicolor infrared imaging can be performed without the need for a cooling subsystem.

Efficacy of Liquid, Air, and Phase Change Material Torso Cooling During Light Exercise While Wearing NBC Clothing

DTIC Science & Technology

1998-03-01

and Thermal Comfort 6 Blood Sampling 6 Statistical Analyses 6 RESULTS 7 Indices of Hydration Status 7 Liquid-Cooling and PCM Cooling Vests...of Uncooled Sites 12 Vapour Pressure 12 Ratings of Thermal Comfort and Perceived Exertion 18 Indices of Heat Tolerance 18 DISCUSSION 20...ill Figures 8A and B Changes in ratings of thermal comfort of the torso and whole body during light exercise at 40°C and 30% relative humidity while