Novel Tribotester for Cylinder Liner/Piston Ring Contacts of Two Stroke Marine Diesel Engines

DEFF Research Database (Denmark)

Pedersen, Michael Torben; Imran, Tajammal; Klit, Peder

2009-01-01

A good tribological description for the cylinder liner and piston ring materials is always desired in order to achieve an improved combination of the materials. The piston ring package in a two-stroke-diesel engine operates in three lubrication regimes and the materials must be characterized...... in relation to this before a final selection is made. A tribo-test-apparatus is developed to study the tribological performance and to rank the different combinations of cylinder liner and piston ring materials of two stroke marine diesel engines. The test apparatus is based on the block-on-ring principle...

A discussion of the several types of two-stroke-cycle engines

Science.gov (United States)

Venediger, Herbert J

1935-01-01

This report discusses different types of two-stroke engines as well as the three most important design factors: volume of scavenge and charge delivery, scavenging process (scavenging result), and result of charge. Some of the types of engines discussed include: single cylinder with crank-chamber scavenge pump and auxiliary suction piston linked to working connecting rod; and two cylinder engines with a rotary scavenge pump arrangement. Three and four cylinder engines are also discussed in various designs.

Performance optimization of a Two-Stroke supercharged diesel engine for aircraft propulsion

International Nuclear Information System (INIS)

Carlucci, Antonio Paolo; Ficarella, Antonio; Trullo, Gianluca

2016-01-01

Highlights: • A Two-Stroke diesel engine for aircraft propulsion was modeled with a 0D/1D approach. • The results of the 0D/1D model are compared with those resulting from a 3D model. • The effect of several design and thermodynamic parameters have been analyzed. • Guidelines for the optimization of engine performance are provided. - Abstract: In Two-Stroke engines, the cylinder filling efficiency is antithetical to the cylinder scavenging efficiency; moreover, both of them are influenced by geometric and thermodynamic parameters characterizing the design and operation of both the engine and the related supercharging system. Aim of this work is to provide several guidelines about the definition of design and operation parameters for a Two-Stroke two banks Uniflow diesel engine, supercharged with two sequential turbochargers and an aftercooler per bank, with the goal of either increasing the engine brake power at take-off or decreasing the engine fuel consumption in cruise conditions. The engine has been modeled with a 0D/1D modeling approach. Then, the model capability in describing the effect of several parameters on engine performance has been assessed comparing the results of 3D simulations with those of 0D/1D model. The validated 0D/1D model has been used to simulate the engine behavior varying several design and operation engine parameters (exhaust valves opening and closing angles and maximum valve lift, scavenging ports opening angle, distance between bottom edge of the scavenging ports and bottom dead center, area of the single scavenging port and number of ports, engine volumetric compression ratio, low and high pressure compressor pressure ratios, air/fuel ratio) on a wide range of possible values. The parameters most influencing the engine performance are then recognized and their effect on engine thermodynamic behavior is discussed. Finally, the system configurations leading to best engine power at sea level and lowest fuel consumption in cruise

Integrated Analysis of the Scavenging Process in Marine Two-Stroke Diesel Engines

DEFF Research Database (Denmark)

Andersen, Fredrik Herland

Large commercial ships such as container vessels and bulk carriers are propelledby low-speed, uniow scavenged two-stroke diesel engines. An integralin-cylinder process in this type of engine is the scavenging process, where the burned gases from the combustion process are evacuated through...... receiver fora two-stroke diesel engine. Time resolved boundary conditions corresponding to measurements obtained from an operating engine as well as realistic initial conditions are used in the simulations. The CFD model provides a detailed description of the in-cylinder ow from exhaust valve opening (EVO...... in the scavenge and exhaust receivers increase while the scavenge port exposure time, tscav, decrease. Further the scavenging pressure is varied while the engine speed is kept constant. From the perspective of the scavenging process this will resemble a load sweep following a generator curve. The scavenge port...

Two-stroke engine with gaseous and liquid fuel injection

Energy Technology Data Exchange (ETDEWEB)

Laursen, Rene Sejer [MAN Diesel and Turbo SE, Copenhagen (Denmark)

2012-08-15

The need to lower emissions of CO{sub 2}, NO{sub x}, SO{sub x} and particulates as well as rising oil prices have increased engine operators' interest in alternative fuels and fuel flexibility. The low speed two-stroke ME-GI and ME-LGI dual-fuel engines with diesel pilot injection from MAN Diesel and Turbo offer the opportunity of utilising fuels such as LNG, LPG, and methanol in a wide range of liquid to gaseous fuel ratios. (orig.)

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

Energy Technology Data Exchange (ETDEWEB)

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 deterioration 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.

The Tracer Gas Method of Determining the Charging Efficiency of Two-stroke-cycle Diesel Engines

Science.gov (United States)

Schweitzer, P H; Deluca, Frank, Jr

1942-01-01

A convenient method has been developed for determining the scavenging efficiency or the charging efficiency of two-stroke-cycle engines. The method consists of introducing a suitable tracer gas into the inlet air of the running engine and measuring chemically its concentration both in the inlet and exhaust gas. Monomethylamine CH(sub 3)NH(sub 2) was found suitable for the purpose as it burns almost completely during combustion, whereas the "short-circuited" portion does not burn at all and can be determined quantitatively in the exhaust. The method was tested both on four-stroke and on two-stroke engines and is considered accurate within 1 percent.

Experimental and numerical investigation of sprays in two stroke diesel Engines

DEFF Research Database (Denmark)

Dam, Bjarke Skovgård

2007-01-01

. The latter is the subject of this dissertation. The theory and experimental findings on diesel sprays are investigated, including e.g. spray parameters and droplet break up. It is found that no complete theory is yet present and large challenges lie ahead. Generally, there is fairly good consensus on which......The control of the injected spray is important when optimizing performance and reducing emissions from diesel engines. The research community has conducted extensive research especially on smaller four stroke engines, but so far only little has been done on sprays in large two stroke engines...... have different scales and other designs than those used in the literature, so extending results from the literature will require experiments on this particular type of setup. Numerical investigations of diesel sprays are performed using the Eulerian/Lagrangian engine CFD code Kiva. In agreement...

MODELING OF ELECTRONIC GASOLINE INJECTION PROCESSES IN TWO STROKE ENGINE

Directory of Open Access Journals (Sweden)

Hraivoronskyi, Y.

2013-06-01

Full Text Available Basic provision of the processes developed mode, occurring in ignition fuel system with electronically controlled two stroke engine with positive ignition are given. Fuel injection process’ calculation results for the case of placing fuel injector into intake system presented.

TOPSIS Multi-Criteria Decision Modeling Approach for Biolubricant Selection for Two-Stroke Petrol Engines

Directory of Open Access Journals (Sweden)

Masoud Dehghani Soufi

2015-12-01

Full Text Available Exhaust pollutants from two-stroke petrol engines are a problem for the environment. Biolubricants are a new generation of renewable and eco-friendly vegetable-based lubricants, which have attracted a lot of attention in recent years. In this paper, the applicability of the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS method to support the process of building the scoring system for selecting an appropriate two-stroke lubricant has been analyzed. For this purpose, biolubricants (TMP-triesters based on castor oil, palm oil, and waste cooking oil were produced and then utilized in a 200 cc two-stroke gasoline engine to investigate their effects on its performance and exhaust emissions. The results obtained from the use of the entropy technique in the TOPSIS algorithm showed that palm oil-based lubricant took up the greatest distance from the Negative Ideal Solution (NIS and was selected as the most optimal lubricant for these types of engines.

Lightweight two-stroke cycle aircraft diesel engine technology enablement program, volume 2

Science.gov (United States)

Freen, P. D.; Berenyi, S. G.; Brouwers, A. P.; Moynihan, M. E.

1985-01-01

An experimental Single Cylinder Test Engine Program is conducted to confirm the analytically projected performance of a two-stroke cycle diesel engine for aircraft applications. Testing confirms the ability of a proposed 4-cylinder version of such an engine to reach the target power at altitude in a highly turbocharged configuration. The experimental program defines all necessary parameters to permit a design of a multicylinder engine for eventual flight applications.

Design and simulation of a two- or four-stroke free-piston engine generator for range extender applications

International Nuclear Information System (INIS)

Jia, Boru; Smallbone, Andrew; Zuo, Zhengxing; Feng, Huihua; Roskilly, Anthony Paul

2016-01-01

Highlights: • A FPE model operated in two thermodynamic cycles is presented. • The engine performance for both gas exchange cycles are described. • Power distribution with different operation parameters are provided. • Advantages and disadvantages for the two thermodynamic cycles are summarised. - Abstract: Free-piston engines (FPEs) are known to have a greater thermal efficiency (40–50%) than an equivalent and more conventional four-stroke reciprocating engines (30–40%). Modern FPEs are proposed for the generation of electric and hydraulic power, with a potential application in hybrid electric vehicles. The numerous FPE configurations considered to date have almost exclusively operated using a two-stroke thermodynamic cycle to improve the thermal efficiency, however it is well known that the application of two-stoke cycles can be limited by noise and exhaust gas emissions constraints. In this article, a numerical model is used to investigate the techno-feasibility of operating Newcastle University’s FPE prototype using a two- or four-stroke thermodynamic cycle. If operated as a four-stroke cycle, the linear generator must be used as both a motor and a generator resulting in a more irregular piston motion compared to corresponding operating in a two-stroke cycle. In four-stroke cycles, almost half the indicated power is consumed in overcoming the pumping losses of the motoring process. Whilst the heat release process is appears to be closer to a constant volume process when operated on two-stroke engine cycle, the peak cylinder pressure and compression ratio proved lower. In addition, a narrower power range is reported for a four-stroke cycle despite a corresponding higher thermal efficiency.

Side branch absorber for exhaust manifold of two-stroke internal combustion engine

Science.gov (United States)

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.

Reaction of Sulfuric Acid in Lube Oil: Implications for Large Two-Stroke Diesel Engines

DEFF Research Database (Denmark)

Lejre, Kasper Hartvig; Kiil, Søren; Glarborg, Peter

2017-01-01

Slow-steaming operation and an increased pressure in the combustion chamber have contributed to increased sulfuric acid (H2SO4) condensation on the cylinder liners in large two-stroke marine diesel engines, thus causing increased corrosion wear. To cope with this, lube oils are formulated...... of CaCO3 compared to the condensed H2SO4. The observed corrosion wear in large two-stroke marine diesel engines could consequently be attributed to local molar excess of H2SO4 compared to CaCO3 reverse micelles on the cylinder liners....

A 50 cc Two-Stroke DI Compression Ignition Engine Fuelled by DME

DEFF Research Database (Denmark)

Hansen, Kim Rene; Nielsen, Claus Suldrup; Sorenson, Spencer C

2008-01-01

efficiency to even the smallest engines. A 50cc crankcase scavenged two-stroke CI engine was built based on moped parts. The major alterations were a new cylinder head and a 100 bar DI system using a GDItype injector. Power is limited by carbon monoxide emission but smoke-free operation and NOx less than 200...

Simulation Modeling and Optimization of Uniflow Scavenging System Parameters on Opposed-Piston Two-Stroke Engines

Directory of Open Access Journals (Sweden)

Fukang Ma

2018-04-01

Full Text Available Based on the introduction of opposed-piston two-stroke (OP2S gasoline direct injection (GDI engines, the OP2S-GDI engine working principle and scavenging process were analyzed. GT-Power software was employed to model the working process based on the structural style and principle of OP2S-GDI engine. The tracer gas method and OP2S-GDI engine experiment were employed for model validation at full load of 6000 rpm. The OP2S-GDI engine scavenging system parameters were optimized, including intake port height stroke ratio, intake port circumference ratio, exhaust port height stroke ratio, exhaust port circumference ratio, and opposed-piston motion phase difference. At the same time, the effect of the port height stroke ratio and opposed-piston motion phase difference on effective compression ratio and expansion ratio were considered, and the indicated work was employed as the optimization objective. A three-level orthogonal experiment was applied in the calculation process to reduce the calculation work. The influence and correlation coefficient on the scavenging efficiency and delivery ratio were investigated by the orthogonal experiment analysis of intake and exhaust port height stroke ratio and circular utilization. The effect of the scavenging system parameters on delivery ratio, scavenging efficiency and indicated work were calculated to obtain the best parameters. The results show that intake port height stroke ratio is the main factor for the delivery ratio, while exhaust port height stroke ratio is the main factor to engine delivery ratio and scavenging efficiency.

Heat Transfer in Large Two-Stroke Marine Diesel Engines

DEFF Research Database (Denmark)

Jensen, Michael Vincent

Heat transfer between the cylinder gas and the piston surface during combustion in large two-stroke uniflow scavenged marine diesel engines has been investigated in the present work. The piston surface experiences a severe thermal load during combustion due to the close proximity of the combustion...... zone to the surface. At the same time, cooling of the piston crown is relatively complicated. This can cause large thermal stresses in the piston crown and weakening of the material strength, which may be critical as it can lead to formation of cracks. Information about the piston surface heat transfer...... is thus important for the engine manufactures. The piston surface heat transfer was studied in the event of impingement of hot combustion products on the piston during combustion, and an estimate was obtained of the peak heat flux level experienced on the piston surface. The investigation was carried out...

Fire Engine Support and On-scene Time in Prehospital Stroke Care - A Prospective Observational Study.

Science.gov (United States)

Puolakka, Tuukka; Väyrynen, Taneli; Erkkilä, Elja-Pekka; Kuisma, Markku

2016-06-01

Introduction On-scene time (OST) previously has been shown to be a significant component of Emergency Medical Services' (EMS') operational delay in acute stroke. Since stroke patients are managed routinely by two-person ambulance crews, increasing the number of personnel available on the scene is a possible method to improve their performance. Hypothesis Using fire engine crews to support ambulances on the scene in acute stroke is hypothesized to be associated with a shorter OST. All patients transported to hospital as thrombolysis candidates during a one-year study period were registered by the ambulance crews using a case report form that included patient characteristics and operational EMS data. Seventy-seven patients (41 [53%] male; mean age of 68.9 years [SD=15]; mean Glasgow Coma Score [GCS] of 15 points [IQR=14-15]) were eligible for the study. Forty-five cases were managed by ambulance and fire engine crews together and 32 by the ambulance crews alone. The median ambulance response time was seven minutes (IQR=5-10) and the fire engine response time was six minutes (IQR=5-8). The number of EMS personnel on the scene was six (IQR=5-7) and two (IQR=2-2), and the OST was 21 minutes (IQR=18-26) and 24 minutes (IQR=20-32; P =.073) for the groups, respectively. In a following regression analysis, using stroke as the dispatch code was the only variable associated with short (engine crews to support ambulances in acute stroke care was not associated with a shorter on-scene stay when compared to standard management by two-person ambulance crews alone. Using stroke as the dispatch code was the only variable that was associated independently with a short OST. Puolakka T , Väyrynen T , Erkkilä E-P , Kuisma M . Fire engine support and on-scene time in prehospital stroke care - a prospective observational study. Prehosp Disaster Med. 2016;31(3):278-281.

Dynamic and Thermodynamic Examination of a Two-Stroke Internal Combustion Engine

OpenAIRE

İPCİ, Duygu; KARABULUT, Halit

2016-01-01

In this study the combined dynamic and thermodynamic analysis of a two-stroke internal combustion engine was carried out. The variation of the heat, given to the working fluid during the heating process of the thermodynamic cycle, was modeled with the Gaussian function. The dynamic model of the piston driving mechanism was established by means of nine equations, five of them are motion equations and four of them are kinematic relations. Equations are solved by using a numerical method based o...

Charging process analysis of an opposed-piston two-stroke aircraft Diesel engine

Directory of Open Access Journals (Sweden)

Grabowski Łukasz

2017-01-01

Full Text Available This paper presents the research results on a 1D model of an opposed-piston two-stroke aircraft Diesel engine. The research aimed at creating a model of the engine in question to investigate how engine performance is affected by the compressor gear ratio. The power was constant at all the operating points. The research results are presented as graphs of power consumed by the compressor, compressor efficiency and brake specific fuel consumption. The optimal range of compressor gear ratio in terms of engine efficiency was defined from the research results.

Two Stroke Diesel Engines for Large Ship Propulsion

DEFF Research Database (Denmark)

Haider, Sajjad

In low speed large two-stroke marine diesel engines, uniflow scavenging is used to remove the exhaust gases from the cylinder and fill the cylinder with fresh air charge for the next cycle. The swirl enhances the mixing of fuel with air and improves combustion efficiency. The thesis focuses...... downstream. As the port closes, the mixing of smoke particles in the core with surrounding regions is enhanced. The hollow conical smoke pattern disappears and resembles to a jet. Laser Doppler Anemometry measurements are conducted in the swirl generator and at the entrance to the test cylinder. The results...

Testing of Bearing Materials for Large Two-stroke Marine Diesel Engines

DEFF Research Database (Denmark)

Klit, Peder; Persson, Sebastian; Vølund, Anders

2013-01-01

In large two-stroke marine diesel engines bearings are designed with the intention that these need not be replaced during the life of the engine. The design has shown very good service experiences. The design parameters of the main bearings are, among others, based on the average maximum specific...... load which the bearing should operate under. In general, the frictional loss is less than 1% of the nominal power of the engine but is still a target for optimization. Fatigue mechanisms of bearing lining material are not fully understood and the design limits with regards to minimum oil film thickness...

Testing of bearing materials for large two-stroke marine diesel engines

DEFF Research Database (Denmark)

Vølund, Anders; Klit, Peder; Persson, Sebastian

2017-01-01

In large two-stroke marine diesel engines, bearings are designed to last the lifetime of the engine. The design has shown very good service experiences. The design parameters of the main bearings are, among others, based on the average maximum specific load which the bearing should operate under....... In general, the frictional loss is less than 1% of the nominal power of the engine but is still a target for optimization. Fatigue mechanisms of bearing lining material are not fully understood and the design limits with regards to minimum oil film thickness, max oil film pressure and oil film pressure...

Influence of piston displacement on the scavenging and swirling flow in two-stroke diesel engines

DEFF Research Database (Denmark)

Obeidat, Anas; Haider, Sajjad; Ingvorsen, Kristian Mark

We study the effect of piston motion on the in-cylinder swirling flow in a low speed, large two-stroke marine diesel engine. The work involves experimental, and numerical simulation using OpenFOAM platform, Large Eddy Simulation was used with three different models, One equation Eddy, Dynamic One...

Optimizing the Performance of a 50cc Compression Ignition Two-Stroke Engine Operating on Dimethyl Ether

DEFF Research Database (Denmark)

Hansen, Kim Rene; Dolriis, J.D.; Hansson, C.

2011-01-01

The paper describes the optimization of a 50cc crankcase scavenged two-stroke diesel engine operating on dimethyl ether (DME). The optimization is primarily done with respect to engine efficiency. The underlying idea behind the work is that the low weight, low internal friction and low engine...

Design and experimental investigations on six-stroke SI engine using acetylene with water injection.

Science.gov (United States)

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.

Control-oriented modeling of two-stroke diesel engines with exhaust gas recirculation for marine applications

OpenAIRE

Llamas, Xavier; Eriksson, Lars

2018-01-01

Large marine two-stroke diesel engines are widely used as propulsion systems for shipping worldwide and are facing stricter NOx emission limits. Exhaust gas recirculation is introduced to these engines to reduce the produced combustion NOx to the allowed levels. Since the current number of engines built with exhaust gas recirculation is low and engine testing is very expensive, a powerful alternative for developing exhaust gas recirculation controllers for such engines is to use control-orien...

Combustion Heat Release Rate Comparison of Algae Hydroprocessed Renewable Diesel to F-76 in a Two-Stroke Diesel Engine

Science.gov (United States)

2013-06-01

was recorded. Figure 14 shows the gauge on the rocker arm during calibration . Figure 14. Mechanical Injector Rocker Arm Strain Gauge. D. DATA...RELEASE RATE COMPARISON OF ALGAE HYDROPROCESSED RENEWABLE DIESEL TO F-76 IN A TWO-STROKE DIESEL ENGINE by John H. Petersen June 2013 Thesis...RELEASE RATE COMPARISON OF ALGAE HYDROPROCESSED RENEWABLE DIESEL TO F-76 IN A TWO-STROKE DIESEL ENGINE 5. FUNDING NUMBERS 6. AUTHOR(S) John H

Swirling flow in model of large two-stroke diesel engine

DEFF Research Database (Denmark)

Ingvorsen, Kristian Mark; Meyer, Knud Erik; Schnipper, Teis

2012-01-01

A scale model of a simplified cylinder in a uniflow scavenged large two-stroke marine diesel engine is constructed to investigate the scavenging process. Angled ports near the bottom of the cylinder liner are uncovered as the piston reaches the bottom dead center. Fresh air enters through the ports...... forcing the gas in the cylinder to leave through an exhaust valve located in the cylinder head. The scavenging flow is a transient (opening/closing ports) confined port-generated turbulent swirl flow, with complex phenomena such as central recirculation zones, vortex breakdown and vortex precession...

Research on the Common Rail Pressure Overshoot of Opposed-Piston Two-Stroke Diesel Engines

OpenAIRE

Yi Lu; Changlu Zhao; Zhe Zuo; Fujun Zhang; Shuanlu Zhang

2017-01-01

The common rail pressure has a direct influence on the working stability of Opposed-Piston Two-Stroke (OP2S) diesel engines, especially on performance indexes such as power, economy and emissions. Meanwhile, the rail pressure overshoot phenomenon occurs frequently due to the operating characteristics of OP2S diesel engines, which could lead to serious consequences. In order to solve the rail pressure overshoot problem of OP2S diesel engines, a nonlinear concerted algorithm adding a speed stat...

Turbulent swirling flow in a model of a uniflow-scavenged two-stroke engine

DEFF Research Database (Denmark)

Ingvorsen, Kristian Mark; Meyer, Knud Erik; Walther, Jens Honore

2013-01-01

The turbulent and swirling flow of a uniflow-scavenged two-stroke engine cylinder is investigated using a scale model with a static geometry and a transparent cylinder. The swirl is generated by 30 equally spaced ports with angles of 0°, 10°, 20°, and 30°. A detailed characterization of the flow...

Experimental investigation of the influence of internal and external EGR on the combustion characteristics of a controlled auto-ignition two-stroke cycle engine

International Nuclear Information System (INIS)

Andwari, Amin Mahmoudzadeh; Aziz, Azhar Abdul; Said, Mohd Farid Muhamad; Latiff, Zulkarnain Abdul

2014-01-01

Highlights: • Investigate the effect of In-EGR, Ex-EGR and octane number on a CAI 2-stroke engine. • Effect of In-EGR, Ex-EGR and octane number on combustion phasing of the engine. • Effect of In-EGR, Ex-EGR and octane number on cyclic variability of the engine. • Identify the CAI combustion upper and lower boundary for operating regions. - Abstract: A two-stroke cycle engine incorporated with a controlled auto-ignition combustion approach presents a high thermodynamic efficiency, ultra-low exhaust emissions and high power-to-weight ratio features for future demand of prime movers. The start of auto-ignition, control of the auto-ignition and its cyclic variability, are major concerns that should be addressed in the combustion timing control of controlled auto-ignition engines. Several studies have been performed to examine the effect of internal exhaust gas recirculation utilization on auto-ignited two-stroke cycle engines. However, far too little attention has been devoted to study on the influence of external exhaust gas recirculation on the cyclic variation and the combustion characteristics of controlled auto-ignition two-stroke cycle engines. The purpose of this study is to examine the influence of external exhaust gas recirculation in combination with internal exhaust gas recirculation on the combustion characteristics and the cyclic variability of a controlled auto-ignition two-stroke engine using fuel with different octane numbers. In a detailed experimental investigation, the combustion-related and pressure-related parameters of the engine are examined and statistically associated with the coefficient of variation and the standard deviation. The outcomes of the investigation indicates that the most influential controlled auto-ignition combustion phasing parameters can be managed appropriately via regulating the internal and external exhaust gas recirculation and fuel octane number. In general, start of auto-ignition and its cyclic variability are

The matching of characteristics of the turbo-supercharging system and two-stroke transport diesel engine

OpenAIRE

Алёхин, Сергей Алексеевич; Герасименко, Владимир Петрович; Опалев, Василий Анатольевич

2013-01-01

The basic problems of the matching of characteristics of turbo-supercharging units and two-stroke transport diesel engines with various number of cylinders are considered. Influence of the number of impeller tiers and other geometrical parameters on the pressure characteristic of the centrifugal compressor and joint action of the compressor and the piston engine is investigated. Effective measures on the optimum coordination of a mechanical turbo-supercharging with a transport diesel engin...

Scavenging processes in high speed two-stroke engines studied with laser diagnostics

Energy Technology Data Exchange (ETDEWEB)

Ekenberg, M.

1998-12-31

The major problem with the carburetted two-stroke engine is the short-circuiting of fuel that occurs during the scavenging phase. This leads to large emissions of unburned hydrocarbons. The object of this thesis has been to map the flow behaviour in the cylinder during the scavenging phase, and to detect differences between different cylinder designs. The measurement techniques used has been Laser Doppler Velocimetry (LDV), Laser Induced Fluorescence (LIF) and Laser Sheet Droplet Illumination (LSDI). Of these measurement methods, LDV and LSDI has been used inside the cylinder. LIF was used outside the exhaust port. All measurements were performed in engines running at their rated speeds, 9000 rpm for three of the designs and 5800 rpm for one design. All engines were run at full load with combustion. The LDV measurements inside the cylinder show that cylinders with cup handle transfer channels have a flow pattern inside the cylinder that gives less short-circuiting, and hence less emissions of hydrocarbons, than the cylinder with open transfer channels has. The LIF measurements outside the exhaust port show that the HC emissions that are caused by short-circuiting comes earlier in the scavenging phase for the cylinder with open transfer channels than is the case for the cylinders with cup handle transfer channels. The LSDI measurements in the cylinder give the transfer channel flow angle, for the cylinders with cup handle transfer channels. For the cylinder with open transfer channels, the results are not as useful; fuel droplet vaporization close to the exhaust port ruins the results 35 refs, 43 figs

Performance and emission characteristics of LPG powered four stroke SI engine under variable stroke length and compression ratio

International Nuclear Information System (INIS)

Ozcan, Hakan; Yamin, Jehad A.A.

2008-01-01

A computer simulation of a variable stroke length, LPG fuelled, four stroke, single cylinder, water cooled spark ignition engine was done. The engine capacity was varied by varying the stroke length of the engine, which also changed its compression ratio. The simulation model developed was verified with experimental results from the literature for both constant and variable stroke engines. The performance of the engine was simulated at each stroke length/compression ratio combination. The simulation results clearly indicate the advantages and utility of variable stroke engines in fuel economy and power issues. Using the variable stroke technique has significantly improved the engine's performance and emission characteristics within the range studied. The brake torque and power have registered an increase of about 7-54% at low speed and 7-57% at high speed relative to the original engine design and for all stroke lengths and engine speeds studied. The brake specific fuel consumption has registered variations from a reduction of about 6% to an increase of about 3% at low speed and from a reduction of about 6% to an increase of about 8% at high speed relative to the original engine design and for all stroke lengths and engine speeds studied. On the other hand, an increase of pollutants of about 0.65-2% occurred at low speed. Larger stroke lengths resulted in a reduction of the pollutants level of about 1.5% at higher speeds. At lower stroke lengths, on the other hand, an increase of about 2% occurred. Larger stroke lengths resulted in increased exhaust temperature and, hence, make the exhaust valve work under high temperature

Gasoline-related organics in Lake Tahoe before and after prohibition of carbureted two-stroke engines

Science.gov (United States)

Lico, M.S.

2004-01-01

On June 1, 1999, carbureted two-stroke engines were banned on waters within the Lake Tahoe Basin of California and Nevada. The main gasoline components MTBE (methyl tert-butyl ether) and BTEX (benzene, toluene, ethylbenzene, and xylenes) were present at detectable concentrations in all samples taken from Lake Tahoe during 1997-98 prior to the ban. Samples taken from 1999 through 2001 after the ban contained between 10 and 60 percent of the pre-ban concentrations of these compounds, with MTBE exhibiting the most dramatic change (a 90 percent decrease). MTBE and BTEX concentrations in water samples from Lake Tahoe and Lower Echo Lake were related to the amount of boat use at the sampling sites. Polycyclic aromatic hydrocarbon (PAH) compounds are produced by high-temperature pyrolytic reactions. They were sampled using semipermeable membrane sampling devices in Lake Tahoe and nearby Donner Lake, where carbureted two-stroke engines are legal. PAHs were detected in all samples taken from Lake Tahoe and Donner Lake. The number of PAH compounds and their concentrations are related to boat use. The highest concentrations of PAH were detected in samples from two heavily used boating areas, Tahoe Keys Marina and Donner Lake boat ramp. Other sources of PAH, such as atmospheric deposition, wood smoke, tributary streams, and automobile exhaust do not contribute large amounts of PAH to Lake Tahoe. Similar numbers of PAH compounds and concentrations were found in Lake Tahoe before and after the ban of carbureted two-stroke engines. ?? by the North American Lake Management Society 2004.

Heat transfer modeling in exhaust systems of high-performance two-stroke engines

OpenAIRE

Lujan Martinez, José Manuel; Climent Puchades, Héctor; Olmeda González, Pablo Cesar; JIMENEZ MACEDO, VICTOR DANIEL

2014-01-01

Heat transfer from the hot gases to the wall in exhaust systems of high-performance two-stroke engines is underestimated using steady state with fully developed flow empirical correlations. This fact is detected when comparing measured and modeled pressure pulses in different positions in the exhaust system. This can be explained taking into account that classical expressions have been validated for fully developed flows, a situation that is far from the flow behavior in reciprocating interna...

The Influence of Fuel Sulfur on the Operation of Large Two-Stroke Marine Diesel Engines

DEFF Research Database (Denmark)

Cordtz, Rasmus Faurskov

The present work focusses on SO3/H2SO4 formation and sulfuric acid (H2SO4) condensation in a large low speed 2-stroke marine diesel engine. SO3 formation is treated theoretically from a formulated multizone engine model described in this work that includes a detailed and validated sulfur reaction...... mechanism. Model results show that for a large marine engine generally about 3 % - 6 % of the fuel sulfur converts to SO3 while the remainder leaves the engine as SO2 from which the SO3 is formed during the expansion stroke. SO3 formation scales with the cylinder pressure and inversely with the engine speed...... as also demonstrated by a number of SO3 experiments described in this work. The experiments are carried out with a heavy duty medium speed 4 stroke diesel engine operating on heavy fuel oil including ≈ 2 wt. % sulfur. SO3 was measured successfully in the exhaust gas with the PENTOL SO3 analyzer...

STEADY STATE PERFORMANCES ANALYSIS OF MODERN MARINE TWO-STROKE LOW SPEED DIESEL ENGINE USING MLP NEURAL NETWORK MODEL

Directory of Open Access Journals (Sweden)

Ozren Bukovac

2016-01-01

Full Text Available Compared to the other marine engines for ship propulsion, turbocharged two-stroke low speed diesel engines have advantages due to their high efficiency and reliability. Modern low speed ”intelligent” marine diesel engines have a flexibility in its operation due to the variable fuel injection strategy and management of the exhaust valve drive. This paper carried out verified zerodimensional numerical simulations which have been used for MLP (Multilayer Perceptron neural network predictions of marine two-stroke low speed diesel engine steady state performances. The developed MLP neural network was used for marine engine optimized operation control. The paper presents an example of achieving lowest specific fuel consumption and for minimization of the cylinder process highest temperature for reducing NOx emission. Also, the developed neural network was used to achieve optimal exhaust gases heat flow for utilization. The obtained data maps give insight into the optimal working areas of simulated marine diesel engine, depending on the selected start of the fuel injection (SOI and the time of the exhaust valve opening (EVO.

Exhaust Recirculation Control for Reduction of NOx from Large Two-Stroke Diesel Engines

DEFF Research Database (Denmark)

Nielsen, Kræn Vodder

Increased awareness of the detrimental effects on climate, ecosystems and human health have led to numerous restrictions of the emissions from internal combustion engines. Recently the International Maritime Organization has introduced the Tier III standard, which includes a significantly stricter...... the automotive industry, but have only recently been introduced commercially to large two-stroke diesel engines. Recirculation of exhaust gas to the cylinders lowers the oxygen availability and increases the heat capacity during combustion, which in turn leads to less formation of NOx. Experience shows...... of the Tier III standard, while still maintaining maneuverability performance without smoke formation. The design methods acknowledge that engine specific parameter tuning is a scarce resource in the industry and controller complexity is kept to a minimum. An existing dynamic model of the engine and EGR...

Development and validation of a new turbocharger simulation methodology for marine two stroke diesel engine modelling and diagnostic applications

International Nuclear Information System (INIS)

Sakellaridis, Nikolaos F.; Raptotasios, Spyridon I.; Antonopoulos, Antonis K.; Mavropoulos, Georgios C.; Hountalas, Dimitrios T.

2015-01-01

Engine cycle simulation models are increasingly used in diesel engine simulation and diagnostic applications, reducing experimental effort. Turbocharger simulation plays an important role in model's ability to accurately predict engine performance and emissions. The present work describes the development of a complete engine simulation model for marine Diesel engines based on a new methodology for turbocharger modelling utilizing physically based meanline models for compressor and turbine. Simulation accuracy is evaluated against engine bench measurements. The methodology was developed to overcome the problem of limited experimental maps availability for compressor and turbine, often encountered in large marine diesel engine simulation and diagnostic studies. Data from the engine bench are used to calibrate the models, as well as to estimate turbocharger shaft mechanical efficiency. Closed cycle and gas exchange are modelled using an existing multizone thermodynamic model. The proposed methodology is applied on a 2-stroke marine diesel engine and its evaluation is based on the comparison of predictions against measured engine data. It is demonstrated model's ability to predict engine response with load variation regarding both turbocharger performance and closed cycle parameters, as well as NOx emission trends, making it an effective tool for both engine diagnostic and optimization studies. - Highlights: • Marine two stroke diesel engine simulation model. • Turbine and compressor simulation using physical meanline models. • Methodology to derive T/C component efficiency and T/C shaft mechanical efficiency. • Extensive validation of predictions against experimental data.

Development and validation of a 5 stroke engine for range extenders application

International Nuclear Information System (INIS)

Kéromnès, A.; Delaporte, B.; Schmitz, G.; Le Moyne, L.

2014-01-01

Highlights: • We have designed and built an innovative five stroke internal combustion engine. • The design includes an innovative exhaust gas management system, the smart waste gate. • The turbocharged port-injection spark ignition engine has a fuel conversion efficiency of 36%. - Abstract: A 5-stroke turbo-charged port-injection spark-ignition engine has been developed in the present study for use as a range extender or series-hybrid main power source. The development and the design of the engine are based on 0D/1D model and experimental results have been compared with the engine model. The 5-stroke engine is a three-cylinder in which two cylinders perform a four-stroke cycle and alternatively a second expansion of the burnt gases is performed in the third cylinder. The boost pressure delivered by the turbocharger is controlled by a particular innovative system called “smart wastegate”, different from a conventional wastegate, consisting in a variable valve timing of the two exhaust valves of the low pressure cylinder. The engine develops up to 40 kW for a speed range of 3500–4500 rpm. BSFC is 226 g/kW.h which corresponds to a fuel conversion efficiency of 36.1%. This efficiency can be achieved for an engine speed of 4000 rpm and a brake power of 32.5 kW, which are notable scores for an MPI two-valve per cylinder engine. Expected optimum should be below 217 g/kW.h BSFC and over 90 N.m torque. The engine has been tested over a wide range of conditions; model predictions and experimental results are compared and combustion efficiency increase discussed

Highly efficient 6-stroke engine cycle with water injection

Science.gov (United States)

Szybist, James P; Conklin, James C

2012-10-23

A six-stroke engine cycle having improved efficiency. Heat is recovered from the engine combustion gases by using a 6-stroke engine cycle in which combustion gases are partially vented proximate the bottom-dead-center position of the fourth stroke cycle, and water is injected proximate the top-dead-center position of the fourth stroke cycle.

Initial testing of a variable-stroke Stirling engine

Science.gov (United States)

Thieme, L. G.

1985-01-01

In support of the U.S. Department of Energy's Stirling Engine Highway Vehicle Systems Program, NASA Lewis Research Center is evaluating variable-stroke control for Stirling engines. The engine being tested is the Advenco Stirling engine; this engine was manufactured by Philips Research Laboratories of the Netherlands and uses a variable-angle swash-plate drive to achieve variable stroke operation. The engine is described, initial steady-state test data taken at Lewis are presented, a major drive system failure and subsequent modifications are described. Computer simulation results are presented to show potential part-load efficiency gains with variable-stroke control.

A methodology for laser diagnostics in large-bore marine two-stroke diesel engines

International Nuclear Information System (INIS)

Hult, J; Mayer, S

2013-01-01

Large two-stroke diesel engines for marine propulsion offer several challenges to successful implementation of the laser diagnostic techniques applied extensively in smaller automotive engines. For this purpose a fully operational large-bore engine has been modified to allow flexible optical access, through 24 optical ports with clear diameters of 40 mm. By mounting the entire optical set-up directly to the engine, effects of the vigorous vibrations and thermal drifts on alignment can be minimized. Wide-angle observation and illumination, as well as relatively large aperture detection, is made possible through mounting of optical modules and relays inside optical ports. This allows positioning of the last optical element within 10 mm from the cylinder wall. Finally, the implementation on a multi-cylinder engine allows for flexible and independent operation of the optically accessible cylinder for testing purposes. The performance of the integrated optical engine and imaging system developed is demonstrated through laser Mie scattering imaging of fuel jet structures, from which information on liquid penetration and spray angles can be deduced. Double pulse laser-sheet imaging of native in-cylinder structures is also demonstrated, for the purpose of velocimetry. (paper)

Numerical Simulation of Condensation of Sulfuric Acid and Water in a Large Two-stroke Marine Diesel Engine

DEFF Research Database (Denmark)

Walther, Jens Honore; Karvounis, Nikolas; Pang, Kar Mun

2016-01-01

We present results from computational fluid dynamics simulations of the condensation of sulfuric acid (H2SO4) and water (H2O) in a large two-stroke marine diesel engine. The model uses a reduced n-heptane skeletal chemical mechanism coupled with a sulfur subsetto simulate the combustion process...

A comparison between Miller and five-stroke cycles for enabling deeply downsized, highly boosted, spark-ignition engines with ultra expansion

International Nuclear Information System (INIS)

Li, Tie; Wang, Bin; Zheng, Bin

2016-01-01

Highlights: • Deeply downsized, highly boosted SI engine with ultra-expansion cycle is studied. • The Miller and five stroke cycles are compared on BSFC improvements and WOT performance. • The mechanism of fuel conversion efficiency improvement at various loads is discussed. • Performance of the two-stage boosting system for the downsized SI engine is investigated. • A unique strategy using the bypass for the five-stroke engine is proposed. - Abstract: It has been well known that the engine downsizing combined with intake boosting is an effective way to improve the fuel conversion efficiency without penalizing the engine torque performance. However, the potential of engine downsizing is not yet fully explored, and the major hurdles include the knocking combustion and the pre-turbine temperature limit, owing to the aggressive intake boosting. Using the engine cycle simulation, this paper compares the effects of the Miller and five stroke cycles on the performance of the deeply downsized and highly boosted SI engine, taking the engine knock and pre-turbine temperature into consideration. In the simulation, the downsizing is implemented by reducing the combustion cylinder number from four to two, while a two stage boosting system is designed for the deeply downsized engine to ensure the wide-open-throttle (WOT) performance comparable to the original four cylinder engine. The Miller cycle is realized by varying the intake valve timing and lift, while the five stroke cycle is enabled with addition of an extra expansion cylinder between the two combustion cylinders. After calibration and validation of the engine cycle simulation models using the experimental data in the original engine, the performances of the deeply downsized engines with both the Miller and five stroke cycles are numerically studied. For the most frequently operated points on the torque-speed map, at low loads the Miller cycle exhibits superior performance over the five-stroke cycle in terms

A method of controlling a large two-stroke turbocharged internal combustion engine and an engine for use in this method

Energy Technology Data Exchange (ETDEWEB)

Kjemtrup, N; Grone, O S

1994-03-03

A large two-stroke turbocharged internal combusted engine has a reactor for reduction of the NO[sub x]-content in the exhaust gas connected upstream of the turbocharger. At least one sensor measures at least one engine parameter and in a control unit it is determined whether the reactor is heated by the exhaust gas, which heating may cause reduced energy supply to the turbocharger. When this is the case the control unit opens for supply of supplementary air or gas to the engine which may be effected by starting an auxiliary blower and/or by actuating a control means in a bypass conduit so that a large amount of exhaust gas with a corresponding increase in the power is delivered to the turbocharger turbine. (author) figs.

An Investigation of the Composition of the Flow in and out of a Two-Stroke Diesel Engine and Air Consumption Ratio

Directory of Open Access Journals (Sweden)

Mirko Grljušić

2017-06-01

Full Text Available The aim of this research was to investigate the mass, substance and energy flow through two-stroke low speed Diesel engines. For this reason, a zero-dimensional model of the combustion in the engine was developed with a calculated amount and composition of exhaust gases. Due to the large amount of oxygen in the exhaust gases, a ratio of real air consumption and stoichiometric amount of air required for combustion of injected fuel was set. The calculated ratio showed that the engine consumed four times more air than needed for combustion in AFRstoich. In this work, this was called the Air Consumption Factor or Ratio, and has not previously been mentioned in scientific literature. The air consumption ratio is defined as a factor of dry or humid air. To be more comprehensive, a modified diagram of the composition of the flow in and out of a two-stroke fuel injection engine and the cylinder was made.

Effects of Surface Irregularities on Piston Ring-Cylinder Tribo Pair of a Two Stroke Motor Engine in Hydrodynamic Lubrication

Directory of Open Access Journals (Sweden)

A. Zavos

2015-03-01

Full Text Available Tribological parameters such as friction, lubrication and wear influence strongly the engine component's life. In this study, a piston ring-cylinder system simulated taking into account the surface modifications under fully flooded lubrication and normal engine conditions. The hydrodynamic pressure field solved based on the Navier Stokes equations by Fluid Structure Interaction analysis. A real experimental data of piston ring-cylinder was used from a two stroke motor engine 50 cc. The surface irregularities are measured by 3D coordinate measurement machine while the engine has been worked about 4000 hours. The friction force, the hydrodynamic pressure, the oil film and the mechanical stresses were predicted for different engine conditions. Results show that the worn profile ring reduces the friction as well as the mechanical stresses increased. Surface condition of worn top ring was observed after a metallurgical profile analysis.

A computational fluid dynamics analysis on stratified scavenging system of medium capacity two-stroke internal combustion engines

Directory of Open Access Journals (Sweden)

Pitta Srinivasa Rao

2008-01-01

Full Text Available The main objective of the present work is to make a computational study of stratified scavenging system in two-stroke medium capacity engines to reduce or to curb the emissions from the two-stroke engines. The 3-D flows within the cylinder are simulated using computational fluid dynamics and the code Fluent 6. Flow structures in the transfer ports and the exhaust port are predicted without the stratification and with the stratification, and are well predicted. The total pressure and velocity map from computation provided comprehensive information on the scavenging and stratification phenomenon. Analysis is carried out for the transfer ports flow and the extra port in the transfer port along with the exhaust port when the piston is moving from the top dead center to the bottom dead center, as the ports are closed, half open, three forth open, and full port opening. An unstructured cell is adopted for meshing the geometry created in CATIA software. Flow is simulated by solving governing equations namely conservation of mass momentum and energy using SIMPLE algorithm. Turbulence is modeled by high Reynolds number version k-e model. Experimental measurements are made for validating the numerical prediction. Good agreement is observed between predicted result and experimental data; that the stratification had significantly reduced the emissions and fuel economy is achieved.

Effects of Scavenging System Configuration on In-Cylinder Air Flow Organization of an Opposed-Piston Two-Stroke Engine

OpenAIRE

Fukang Ma; Changlu Zhao; Fujun Zhang; Zhenfeng Zhao; Shuanlu Zhang

2015-01-01

In-cylinder air flow is very important from the point of view of mixture formation and combustion. In this direction, intake chamber structure and piston crown shape play a very crucial role for in-cylinder air pattern of opposed-piston two-stroke (OP2S) engines. This study is concerned with the three-dimensional (3D) computational fluid dynamics (CFD) analysis of in-cylinder air motion coupled with the comparison of predicted results with the zero-dimensional (0D) parametric model. Three con...

Direct injection of gaseous LPG in a two-stroke SI engine for improved performance

International Nuclear Information System (INIS)

Pradeep, V.; Bakshi, Shamit; Ramesh, A.

2015-01-01

Improvements in a two-stroke, spark-ignition (2S–SI) engine can be realized by curtailing short-circuiting losses effectively through direct injection of the fuel. Liquefied petroleum gas (LPG) is an alternative transportation fuel that is used in several countries. However, limited information is available on LPG fuelled direct injected engines. Hence, there is a need to study these systems as applied to 2S–SI engines in order to bring out their potential benefits. A manifold injected 2S–SI engine is modified for direct injection of LPG, in gaseous form, from the cylinder head. This engine is evaluated for performance, emission and combustion. Evaluation at various throttle positions and constant speed showed that this system can significantly improve the thermal efficiency and lower the hydrocarbon (HC) emissions. Up to 93% reduction in HC emissions and improved combustion rates are observed compared to the conventional manifold injection system with LPG. CO emissions are higher and peak NO emissions are lower with this system due to the presence of richer in–cylinder trapped mixtures and charge stratification. This system can operate with similar injection timings at different throttle positions which make electronic control simpler. It can work with low injection pressures in the range of 4–5 bars. All these advantages are attractive for commercial viability of this engine. - Highlights: • Energy saving, low pressure, direct gaseous LPG injection in engine. • Significant reduction in HC emissions at all operating conditions. • No significant changes in injection timings for different throttle positions.

Concept of Six Stroke Engine

OpenAIRE

P.Naresh

2015-01-01

One of the most difficult challenges in engine technology today is the urgent need to increase engine thermal efficiency. Higher efficiencies mean less fuel consumption and lower atmospheric emissions per unit of work produced by the engine. In 1862 a Frenchman Alphouse Beau de Rochas gives his theory regarding the ideal cycle of the internal combustion engine. This theory is applied by a German engineer named Nikolaus A. Otto, who firstly built a successful four-stroke SI engine in 1876. The...

Calculation of the operational behaviour of uniflow-scavenged two-stroke ship's diesel engines. Beitrag zur berechnung des betriebsverhaltens gleichstromgespuelter zweitakt-schiffsdieselmotoren

Energy Technology Data Exchange (ETDEWEB)

Heeschen, K

1984-01-01

The object of this dissertation was to calculate the operational behaviour of supercharged uniflow-scavenged two-stroke engines; this includes a description of the scavenging process and its effect on the thermodynamics of the whole cycle. The aim is to optimize the diesel engine's functioning and to allow joint operation with other machines for instance propellers. A calculation model is developed for the 3-zone mixed scavenging which, together with the step-by-step cycle calculation supplies the operational data of this type of diesel-engine. This method also allows to make calculations with simplified scavening models for complete mixture and pure displacement and to make comparisons. The calculation model of the 3-zone mixed scavenging also makes it possible to test engines by varying their design parameters. It was proven that an increasing stroke causes the fuel consumption to drop slighty, due to the improved thermodynamics. By varying the compression ratio it was possible to optimize engines for partial-load operation. (HWJ)

Investigation of Different Piston Ring Curvatures on Lubricant Transport along Cylinder Liner in Large Two-Stroke Marine Diesel Engines

DEFF Research Database (Denmark)

Overgaard, Hannibal Christian; Klit, Peder; Vølund, Anders

2016-01-01

A theoretical investigation of the hydrodynamic lubrication of the top compression piston ring in a large two-stroke marine diesel engine is presented. The groove mounted piston ring is driven by the reciprocal motion of the piston. The ring shape follows a circular geometry and the effect...

Investigation of different piston ring curvatures on lubricant transport along cylinder liner in large two-stroke marine diesel engines

DEFF Research Database (Denmark)

Overgaard, H; Klit, P; Vølund, A

2017-01-01

A theoretical investigation of the hydrodynamic lubrication of the top compression piston ring in a large two-stroke marine diesel engine is presented. The groove mounted piston ring is driven by the reciprocal motion of the piston. The ring shape follows a circular geometry and the effect...

Conversion of a micro, glow-ignition, two-stroke engine from nitromethane-methanol blend fuel to military jet propellant (JP-8)

Science.gov (United States)

Wiegand, Andrew L.

The goal of the thesis "Conversion of a Micro, Glow-Ignition, Two-Stroke Engine from Nitromethane-Methanol Blend Fuel to Military Jet Propellant (JP-8)" was to demonstrate the ability to operate a small engine on JP-8 and was completed in two phases. The first phase included choosing, developing a test stand for, and baseline testing a nitromethane-methanol-fueled engine. The chosen engine was an 11.5 cc, glow-ignition, two-stroke engine designed for remote-controlled helicopters. A micro engine test stand was developed to load and motor the engine. Instrumentation specific to the low flow rates and high speeds of the micro engine was developed and used to document engine behavior. The second phase included converting the engine to operate on JP-8, completing JP-8-fueled steady-state testing, and comparing the performance of the JP-8-fueled engine to the nitromethane-methanol-fueled engine. The conversion was accomplished through a novel crankcase heating method; by heating the crankcase for an extended period of time, a flammable fuel-air mixture was generated in the crankcase scavenged engine, which greatly improved starting times. To aid in starting and steady-state operation, yttrium-zirconia impregnated resin (i.e. ceramic coating) was applied to the combustion surfaces. This also improved the starting times of the JP-8-fueled engine and ultimately allowed for a 34-second starting time. Finally, the steady-state data from both the nitromethane-methanol and JP-8-fueled micro engine were compared. The JP-8-fueled engine showed signs of increased engine friction while having higher indicated fuel conversion efficiency and a higher overall system efficiency. The minimal ability of JP-8 to cool the engine via evaporative effects, however, created the necessity of increased cooling air flow. The conclusion reached was that JP-8-fueled micro engines could be viable in application, but not without additional research being conducted on combustion phenomenon and

Modeling the Distribution of Sulfur Compounds in a Large Two Stroke Diesel Engine

DEFF Research Database (Denmark)

Cordtz, Rasmus Lage; Schramm, Jesper; Andreasen, Anders

2013-01-01

In many years large low speed marine diesel engines have consumed heavy fuel oils with sulfur contents in the order of 2.5 - 4.5wt%. Present legislations require that the fuel sulfur is reduced and in near future the limit will be 0.5wt% globally. During combustion most of the sulfur is oxidized...... conditions and sulfur feed. This work presents a computational model of a large low speed two-stroke diesel engine where a 0D multi-zone approach including a detailed reaction mechanism is employed in order to investigate in cylinder formation of gaseous SO3 where fuel injection rates are determined using...... experimental pressure traces. Similarly to NO the SO3 is very sensitive to the rate that fresh air mixes with hot combustion products. Therefore a simple mixing rate is proposed and calibrated in order to meet experimental results of NO. Generally 3 - 5 % of the injected sulfur is oxidized to SO3...

A study of the performance and properties of diamond like carbon (DLC) coatings deposited by plasma chemical vapor deposition (CVD) for two stroke engine components

Energy Technology Data Exchange (ETDEWEB)

Tither, D. [BEP Grinding Ltd., Manchester (United Kingdom); Ahmed, W.; Sarwar, M.; Penlington, R. [Univ. of Northumbria, Newcastle-upon-Tyne (United Kingdom)

1995-12-31

Chemical vapor deposition (CVD) using microwave and RF plasma is arguably the most successful technique for depositing diamond and diamond like carbon (DLC) films for various engineering applications. However, the difficulties of depositing diamond are nearly as extreme as it`s unique combination of physical, chemical and electrical properties. In this paper, the modified low temperature plasma enhanced CVD system is described. The main focus of this paper will be work related to deposition of DLC on metal matrix composite materials (MMCs) for application in two-stroke engine components and results will be presented from SEM, mechanical testing and composition analysis studies. The authors have demonstrated the feasibility of depositing DLC on MMCs for the first time using a vacuum deposition process.

Validation of a zero-dimensional model for prediction of NOx and engine performance for electronically controlled marine two-stroke diesel engines

International Nuclear Information System (INIS)

Scappin, Fabio; Stefansson, Sigurður H.; Haglind, Fredrik; Andreasen, Anders; Larsen, Ulrik

2012-01-01

The aim of this paper is to derive a methodology suitable for energy system analysis for predicting the performance and NO x emissions of marine low speed diesel engines. The paper describes a zero-dimensional model, evaluating the engine performance by means of an energy balance and a two zone combustion model using ideal gas law equations over a complete crank cycle. The combustion process is divided into intervals, and the product composition and flame temperature are calculated in each interval. The NO x emissions are predicted using the extended Zeldovich mechanism. The model is validated using experimental data from two MAN B and W engines; one case being data subject to engine parameter changes corresponding to simulating an electronically controlled engine; the second case providing data covering almost all model input and output parameters. The first case of validation suggests that the model can predict specific fuel oil consumption and NO x emissions within the 95% confidence intervals given by the experimental measurements. The second validation confirms the capability of the model to match measured engine output parameters based on measured engine input parameters with a maximum 5% deviation. - Highlights: ► A fast realistic model of a marine two-stroke low speed diesel engine was derived. ► The model is fast and accurate enough for future complex energy systems analysis. ► The effects of engine tuning were validated with experimental tests. ► The model was validated while constrained by experimental input and output data.

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

Science.gov (United States)

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...

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

Science.gov (United States)

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.

Construction of a Direct Water-Injected Two-Stroke Engine for Phased Direct Fuel Injection-High Pressure Charging Investigations

Science.gov (United States)

Somsel, James P.

1998-01-01

The development of a water injected Orbital Combustion Process (OCP) engine was conducted to assess the viability of using the powerplant for high altitude NASA aircraft and General Aviation (GA) applications. An OCP direct fuel injected, 1.2 liter, three cylinder, two-stroke engine has been enhanced to independently inject water directly into the combustion chamber. The engine currently demonstrates low brake specific fuel consumption capability and an excellent power to weight ratio. With direct water injection, significant improvements can be made to engine power, to knock limits/ignition advance timing, and to engine NO(x) emissions. The principal aim of the testing was to validate a cyclic model developed by the Systems Analysis Branch at NASA Ames Research Center. The work is a continuation of Ames' investigations into a Phased Direct Fuel Injection Engine with High Pressure Charging (PDFI-ITPC).

Constant speed control of four-stroke micro internal combustion swing engine

Science.gov (United States)

Gao, Dedong; Lei, Yong; Zhu, Honghai; Ni, Jun

2015-09-01

The increasing demands on safety, emission and fuel consumption require more accurate control models of micro internal combustion swing engine (MICSE). The objective of this paper is to investigate the constant speed control models of four-stroke MICSE. The operation principle of the four-stroke MICSE is presented based on the description of MICSE prototype. A two-level Petri net based hybrid model is proposed to model the four-stroke MICSE engine cycle. The Petri net subsystem at the upper level controls and synchronizes the four Petri net subsystems at the lower level. The continuous sub-models, including breathing dynamics of intake manifold, thermodynamics of the chamber and dynamics of the torque generation, are investigated and integrated with the discrete model in MATLAB Simulink. Through the comparison of experimental data and simulated DC voltage output, it is demonstrated that the hybrid model is valid for the four-stroke MICSE system. A nonlinear model is obtained from the cycle average data via the regression method, and it is linearized around a given nominal equilibrium point for the controller design. The feedback controller of the spark timing and valve duration timing is designed with a sequential loop closing design approach. The simulation of the sequential loop closure control design applied to the hybrid model is implemented in MATLAB. The simulation results show that the system is able to reach its desired operating point within 0.2 s, and the designed controller shows good MICSE engine performance with a constant speed. This paper presents the constant speed control models of four-stroke MICSE and carries out the simulation tests, the models and the simulation results can be used for further study on the precision control of four-stroke MICSE.

Particulate matter regulation for two-stroke two wheelers: necessity or haphazard legislation?

NARCIS (Netherlands)

Rijkeboer, R.C.; Bremmers, D.A.C.M.; Samaras, Z.; Ntziachristos, L.

2005-01-01

Although interest in particulate emissions has increased considerably during recent years, the subject of particulate matter (PM) emissions from small two-stroke engines used in road vehicles is still largely unexplored. This paper presents the results of an investigation, which examined the typical

Influence of outlet geometry on the swirling flow in a simplfied model of a large two-stroke marine diesel engine

DEFF Research Database (Denmark)

Haider, Sajjad; Schnipper, Teis; Meyer, Knud Erik

We present Stereoscopic particle image velocimetry measurements of the effect of a dummy-valve on the in-cylinder swirling flow in a simplified scale model of a large two-stroke marine diesel engine cylinder using air at room temperature and pressure as the working fluid and Reynolds number 19500...

A highly efficient six-stroke internal combustion engine cycle with water injection for in-cylinder exhaust heat recovery

International Nuclear Information System (INIS)

Conklin, James C.; Szybist, James P.

2010-01-01

A concept adding two strokes to the Otto or Diesel engine cycle to increase fuel efficiency is presented here. It can be thought of as a four-stroke Otto or Diesel cycle followed by a two-stroke heat recovery steam cycle. A partial exhaust event coupled with water injection adds an additional power stroke. Waste heat from two sources is effectively converted into usable work: engine coolant and exhaust gas. An ideal thermodynamics model of the exhaust gas compression, water injection and expansion was used to investigate this modification. By changing the exhaust valve closing timing during the exhaust stroke, the optimum amount of exhaust can be recompressed, maximizing the net mean effective pressure of the steam expansion stroke (MEP steam ). The valve closing timing for maximum MEP steam is limited by either 1 bar or the dew point temperature of the expansion gas/moisture mixture when the exhaust valve opens. The range of MEP steam calculated for the geometry of a conventional gasoline engine and is from 0.75 to 2.5 bars. Typical combustion mean effective pressures (MEP combustion ) 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.

Effects of valve timing, valve lift and exhaust backpressure on performance and gas exchanging of a two-stroke GDI engine with overhead valves

International Nuclear Information System (INIS)

Dalla Nora, Macklini; Lanzanova, Thompson Diórdinis Metzka; Zhao, Hua

2016-01-01

Highlights: • Two-stroke operation was achieved in a four-valve direct injection gasoline engine. • Shorter valve opening durations improved torque at lower engine speeds. • The longer the valve opening duration, the lower was the air trapping efficiency. • Higher exhaust backpressure and lower valve lift reduced the compressor work. - Abstract: The current demand for fuel efficient and lightweight powertrains, particularly for application in downsized and hybrid electric vehicles, has renewed the interest in two-stroke engines. In this framework, an overhead four-valve spark-ignition gasoline engine was modified to run in the two-stroke cycle. The scavenging process took place during a long valve overlap period around bottom dead centre at each crankshaft revolution. Boosted intake air was externally supplied at a constant pressure and gasoline was directly injected into the cylinder after valve closure. Intake and exhaust valve timings and lifts were independently varied through an electrohydraulic valve train, so their effects on engine performance and gas exchanging were investigated at 800 rpm and 2000 rpm. Different exhaust backpressures were also evaluated by means of exhaust throttling. Air trapping efficiency, charging efficiency and scavenge ratio were calculated based on air and fuel flow rates, and exhaust oxygen concentration at fuel rich conditions. The results indicated that longer intake and exhaust valve opening durations increased the charge purity and hence torque at higher engine speeds. At lower speeds, although, shorter valve opening durations increased air trapping efficiency and reduced the estimated supercharger power consumption due to lower air short-circuiting. A strong correlation was found between torque and charging efficiency, while air trapping efficiency was more associated to exhaust valve opening duration. The application of exhaust backpressure, as well as lower intake/exhaust valve lifts, made it possible to increase

The multilevel four-stroke swap engine and its environment

Science.gov (United States)

Uzdin, Raam; Kosloff, Ronnie

2014-09-01

A multilevel four-stroke engine where the thermalization strokes are generated by unitary collisions with thermal bath particles is analyzed. Our model is solvable even when the engine operates far from thermal equilibrium and in the strong system-bath coupling. Necessary operation conditions for the heat machine to perform as an engine or a refrigerator are derived. We relate the work and efficiency of the device to local and non-local statistical properties of the baths (purity, index of coincidence, etc) and put upper bounds on these quantities. Finally, in the ultra-hot regime, we analytically optimize the work and find a striking similarity to results obtained for efficiency at maximal power of classical engines. The complete swap limit of our results holds for any four-stroke quantum Otto engine that is coupled to the baths for periods that are significantly longer than the thermal relaxation time.

The multilevel four-stroke swap engine and its environment

International Nuclear Information System (INIS)

Uzdin, Raam; Kosloff, Ronnie

2014-01-01

A multilevel four-stroke engine where the thermalization strokes are generated by unitary collisions with thermal bath particles is analyzed. Our model is solvable even when the engine operates far from thermal equilibrium and in the strong system–bath coupling. Necessary operation conditions for the heat machine to perform as an engine or a refrigerator are derived. We relate the work and efficiency of the device to local and non-local statistical properties of the baths (purity, index of coincidence, etc) and put upper bounds on these quantities. Finally, in the ultra-hot regime, we analytically optimize the work and find a striking similarity to results obtained for efficiency at maximal power of classical engines. The complete swap limit of our results holds for any four-stroke quantum Otto engine that is coupled to the baths for periods that are significantly longer than the thermal relaxation time. (paper)

EMISSIONS FROM TWO OUTBOARD ENGINES OPERATING ON REFORMULATED GASOLINE CONTAINING MTBE

Science.gov (United States)

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...

Modelling of Combustion and Pollutant Formation in a Large, Two-Stroke Marine Diesel Engine using Integrated CFD-Skeletal Chemical Mechanism

DEFF Research Database (Denmark)

Pang, Kar Mun; Karvounis, Nikolas; Schramm, Jesper

In this reported work, simulation studies of in-cylinder diesel combustion and pollutant formation processesin a two-stroke, low-speed uniflow-scavenged marine diesel engine are presented. Numerical computation is performed by integrating chemical kinetics into CFD computations. In order...... to minimize the computational runtime, an in-house skeletal n-heptane chemical mechanism is coupled with the CFD model. This surrogate fuel model comprises 89 reactions with 32 species essential to diesel ignition/combustion processes as well as the formation of soot precursors and nitrogen monoxide (NO......). Prior to the marine engine simulation,coupling of the newly developed surrogate fuel model and a revised multi-step soot model [1] is validated on the basis of optical diagnostics measurement obtained at varying ambient pressure levels [2]. It is demonstrated that the variation of ignition delay times...

Determination of geographic variance in stroke prevalence using Internet search engine analytics.

Science.gov (United States)

Walcott, Brian P; Nahed, Brian V; Kahle, Kristopher T; Redjal, Navid; Coumans, Jean-Valery

2011-06-01

Previous methods to determine stroke prevalence, such as nationwide surveys, are labor-intensive endeavors. Recent advances in search engine query analytics have led to a new metric for disease surveillance to evaluate symptomatic phenomenon, such as influenza. The authors hypothesized that the use of search engine query data can determine the prevalence of stroke. The Google Insights for Search database was accessed to analyze anonymized search engine query data. The authors' search strategy utilized common search queries used when attempting either to identify the signs and symptoms of a stroke or to perform stroke education. The search logic was as follows: (stroke signs + stroke symptoms + mini stroke--heat) from January 1, 2005, to December 31, 2010. The relative number of searches performed (the interest level) for this search logic was established for all 50 states and the District of Columbia. A Pearson product-moment correlation coefficient was calculated from the statespecific stroke prevalence data previously reported. Web search engine interest level was available for all 50 states and the District of Columbia over the time period for January 1, 2005-December 31, 2010. The interest level was highest in Alabama and Tennessee (100 and 96, respectively) and lowest in California and Virginia (58 and 53, respectively). The Pearson correlation coefficient (r) was calculated to be 0.47 (p = 0.0005, 2-tailed). Search engine query data analysis allows for the determination of relative stroke prevalence. Further investigation will reveal the reliability of this metric to determine temporal pattern analysis and prevalence in this and other symptomatic diseases.

A new six stroke single cylinder diesel engine referring Rankine cycle

International Nuclear Information System (INIS)

Chen, Hao; Guo, Qi; Yang, Lu; Liu, Shenghua; Xie, Xuliang; Chen, Zhaoyang; Liu, Zengqiang

2015-01-01

Six stroke engine presented by Conklin and Szybist is an effective way to recover energy of exhaust gas by adding a partial exhaust stroke and steam expansion stroke. Characteristics of the engine are analyzed and its disadvantages are pointed out. A new six stroke diesel engine is presented here. It refers rankine cycle inside cylinder. Total exhaust gas is recompressed and at a relatively low back pressure in the fourth stroke water is injected to which maintains liquid phase until the piston moves to the TDC. At c′ 720 °CA (crank angle) the water becomes saturated. An ideal thermodynamics model of exhaust gas compression, water injection and expansion is constructed to investigate this modification. Properties at characteristic points are calculated to determine the increased indicated work. Results show that the work increases with the advance of water injection timing and the quality of water. The cycle is more efficient and the new engine has potential for saving energy. Moreover, it is forecasted that HC and PM emissions may reform with steam in reality and H 2 is produced which will react with NO X . - Highlights: • A new six stroke diesel engine is introduced and a new ideal cycle is constructed. • Increased indicated work of the cycle proves that the cycle is more efficient. • In reality steam may reform with HC and PM and produced H 2 may react with NO X emission. • The engine has the potential for energy saving and emission reducing

PIV Study of the Effect of Piston Motion on the Confined Swirling Flow in the Scavenging Process in 2-Stroke Marine Diesel Engines

DEFF Research Database (Denmark)

Haider, Sajjad; Meyer, Knud Erik; Schramm, Jesper

2010-01-01

The effect of piston motion on the incylinder swirling flow for a low speed, large two-stroke marine diesel engine is studies using the stereoscopic PIV technique. The measuremenrs are conducted at 5 cross sectional planes along the cylinder length and at piston positions covering the air intake...

Large eddy simulations of the influence of piston position on the swirling flow in a model two-stroke diesel engine

DEFF Research Database (Denmark)

Obeidat, Anas Hassan MohD; Schnipper, Teis; Ingvorsen, Kristian Mark

2014-01-01

Purpose – The purpose of this paper is to study the effect of piston position on the in-cylinder swirling flow in a simplified model of a large two-stroke marine diesel engine. Design/methodology/approach – Large eddy simulations with four different models for the turbulent flow are used: a one...... qualitatively with port closure from a Lamb-Oseen vortex profile to a solid body rotation, while the axial velocity changes from a wake-like profile to a jet-like profile. The numerical results are compared with particle image velocimetry measurements, and in general, the authors find a good agreement. Research...

Research on the Common Rail Pressure Overshoot of Opposed-Piston Two-Stroke Diesel Engines

Directory of Open Access Journals (Sweden)

Yi Lu

2017-04-01

Full Text Available The common rail pressure has a direct influence on the working stability of Opposed-Piston Two-Stroke (OP2S diesel engines, especially on performance indexes such as power, economy and emissions. Meanwhile, the rail pressure overshoot phenomenon occurs frequently due to the operating characteristics of OP2S diesel engines, which could lead to serious consequences. In order to solve the rail pressure overshoot problem of OP2S diesel engines, a nonlinear concerted algorithm adding a speed state feedback was investigated. First, the nonlinear Linear Parameter Varying (LPV model was utilized to describe the coupling relationship between the engine speed and the rail pressure. The Linear Quadratic Regulator (LQR optimal control algorithm was applied to design the controller by the feedback of speed and rail pressure. Second, cooperating with the switching characteristics of injectors, the co-simulation of MATLAB/Simulink and GT-Power was utilized to verify the validity of the control algorithm and analyze workspaces for both normal and special sections. Finally, bench test results showed that the accuracy of the rail pressure control was in the range of ±1 MPa, in the condition of sudden 600 r/min speed increases. In addition, the fuel mass was reduced 76.3% compared with the maximum fuel supply quantity and the rail pressure fluctuation was less than 20 MPa. The algorithm could also be appropriate for other types of common rail system thanks to its universality.

Lubricant transport across the piston ring with flat and triangular lubrication injection profiles on the liner in large two-stroke marine diesel engines

DEFF Research Database (Denmark)

Overgaard, H.; Klit, P.; Vølund, A.

2018-01-01

A theoretical investigation of the lubricant transport across the top compression piston ring in a large two-stroke marine diesel engine is presented. A numerical model for solving Reynolds equation between the piston ring and cylinder liner based on the finite difference method in one dimension...

Experimental investigation of the effects of direct water injection parameters on engine performance in a six-stroke engine

International Nuclear Information System (INIS)

Arabaci, Emre; İçingür, Yakup; Solmaz, Hamit; Uyumaz, Ahmet; Yilmaz, Emre

2015-01-01

Highlights: • Exhaust gas temperature and specific fuel consumption decreased with six stroke engine. • Thermal efficiency increased with water injection. • NO emissions decreased with water injection as the temperature decreased at the end of cycle. • Injection timing should be advanced with the increase of engine speed. • HC and CO emissions decrease until 3000 rpm engine speed. - Abstract: In this study, the effects of water injection quantity and injection timing were investigated on engine performance and exhaust emissions in a six-stroke engine. For this purpose, a single cylinder, four-stroke gasoline engine was converted to six-stroke engine modifying a new cam mechanism and adapting the water injection system. The experiments were conducted at stoichometric air/fuel ratio (λ = 1) between 2250 and 3500 rpm engine speed at full load with liquid petroleum gas. Water injection was performed at three different stages as before top dead center, top dead center and after top dead center at constant injection duration and four different injection pressure 25, 50, 75 and 100 bar. The test results showed that exhaust gas temperature and specific fuel consumption decreased by about 7% and 9% respectively. In contrast, fuel consumption and power output increased 2% and 10% respectively with water injection. Thermal efficiency increased by about 8.72% with water injection. CO and HC emissions decreased 21.97% and 18.23% until 3000 rpm respectively. NO emissions decreased with water injection as the temperature decreased at the end of cycle. As a result, it was seen that engine performance improved when suitable injection timing and injected water quantity were selected due to effect of exhaust heat recovery with water injection

ESTIMATION OF GAS EXCHANGE INDICATORS AT 3-D MODELING OF THE WORKING PROCESS OF THE TWO-STROKE PETROL ENGINE

Directory of Open Access Journals (Sweden)

V. Korohodskyi

2017-06-01

Full Text Available With the help of 3-D modeling of the workflow of a two-stroke engine with spark ignition, crank-chamber scavenging and a carburetor feeding system in the modes of external speed characteristic the indices of gas exchange were evaluated. The simulation results are consistent with the experimental data and 3D simulation results in the AVL FIRE and MTFS® software complexes. The model allows performing optimized calculations of multiphase flow in ICE during experimental design work.

Supercharging system behavior for high altitude operation of an aircraft 2-stroke Diesel engine

International Nuclear Information System (INIS)

Carlucci, Antonio Paolo; Ficarella, Antonio; Laforgia, Domenico; Renna, Alessandro

2015-01-01

Highlights: • Different supercharging architectures have been compared for an aircraft 2T engine. • The supercharging architectures are compared to minimize the fuel consumption. • The architecture with the highest conversion efficiency was determined. - Abstract: Different studies on both 2- and 4-stroke engines have shown how the choice of different supercharging architectures can influence engine performance. Among them, architectures coupling one turbocharger with a mechanical compressor or two turbochargers are found to be the most performing in terms of engine output power and efficiency. However, defining the best supercharging architecture for aircraft 2-stroke engines is a quite complex task because the supercharging system as well as the ambient conditions influence the engine performance/efficiency. This is due to the close interaction between supercharging, trapping, scavenging and combustion processes. The aim of the present work is the comparison between different architectures (single turbocharger, double turbocharger, single turbocharger combined with a mechanical compressor, single turbocharger with an electrically-assisted turbocharger, with intercooler or aftercooler) designed to supercharge an aircraft 2-stroke Diesel engine for general aviation and unmanned aerial vehicles characterized by a very high altitude operation and long fuel distance. A 1D model of the engine purposely designed has been used to compare the performance of the different supercharging systems in terms of power, fuel consumption, and their effect on trapping and scavenging efficiency at different altitudes. The analysis shows that the engine target power is reached by a 2 turbochargers architecture; in this way, in fact, the cylinder filling, and consequently the engine performance, are maximized. Moreover, it is shown that the performance of a 2 turbochargers architecture performance can be further improved connecting electrically and not mechanically the low

Improvement of Fatigue Life of Welded Structural Components of a Large Two-Stroke Diesel Engine by Grinding

DEFF Research Database (Denmark)

Agerskov, Henning; Hansen, Anders V.; Bjørnbak-Hansen, Jørgen

2004-01-01

one side only, with no access to the root side. Various investigations on the fatigue life of the structural components of this new design have been carried out. The present investigation concentrates on the improvement in fatigue life which may be obtained by grinding of the weld toes. The tests...... grinding to m=6 for the test series with grinding. In one of the test series, it was observed that in most cases crack initiation moved from the weld toe to the non-ground surface between the ground areas at the weld toes. Tests were made on steel S 275, on centrally and eccentrically loaded test specimens.......The crankshaft housings of large two-stroke diesel engines are welded structures subjected to constant amplitude loading and designed for infinite life at full design load. A new design of the so-called frame box has been introduced in the engine using butt weld joints of thick plates, welded from...

Post-stroke depression among stroke survivors attending two ...

African Journals Online (AJOL)

Background: The burden of stroke worldwide is increasing rapidly. There is paucity of data on post-stroke depression (PSD) among stroke survivors in Uganda, despite the high prevalence of PSD reported elsewhere. Methods: In a cross-sectional study, we assessed adult participants with confirmed first stroke with a ...

Numerical investigation of soot formation and oxidation processes under large two-stroke marine diesel engine-like conditions using integrated CFD-chemical kinetics

DEFF Research Database (Denmark)

Pang, Kar Mun; Karvounis, Nikolas; Walther, Jens Honore

2016-01-01

n-heptane mechanism and a revised multi-step soot model using laser extinction measurements of diesel soot obtained at different ambient pressure levels in an optical accessible, constant volume chamber experiment. It is revealed that ignition delay times and liftoff lengths generated using the new......In this reported work, multi-dimensional computational fluid dynamics studies of diesel combustion and soot formation processes in a constant volume combustion chamber and a marine diesel engine are carried out. The key interest here is firstly to validate the coupling of a newly developed skeletal...... using the revised soot model agrees reasonably well with the measurements in terms of peak values. The numerical model is subsequently applied to investigate the flame development, soot/nitrogen monoxide formation and heat transfer in a two-stroke, low-speed uniflow-scavenged marine diesel engine...

An Investigation on the Influence of Root Defects on the Fatigue Life of the Welded Structure of a Large Two-Stroke Diesel Engine

DEFF Research Database (Denmark)

Hansen, Anders V.; Olesen, John Forbes; Agerskov, Henning

2004-01-01

-models of the welded joints, are described and the results presented. In addition, large-scale test specimens with controlled lack-of-fusion weld root geometry were manufactured and fatigue tested to develop S-N curves and determine threshold stress intensity factor range values. These were established for opening......The crankshaft housings of large two-stroke diesel engines are welded structures subjected to constant amplitude loading and designed for infinite life at full design load. A new design of the so-called frame box has been introduced in the engine using butt welded joints of thick plates, welded...

Simulation investigation of flow field inside the rotary engine : during intake and compression stroke

Energy Technology Data Exchange (ETDEWEB)

Poojitganont, T.; Berg, H.P.; Izweik, H.T. [Brandenburg Univ. of Technology Cottbus, Cottbus (Germany)

2009-07-01

As a result of continuously increasing oil prices, automotive industries are looking for alternative power sources for their automobiles. An excellent solution is the hybrid system. However due to the additional weight of its batteries, this causes the total weight of the car to increase. This higher battery weight can be compensated by reducing the weight of the engine. A rotary engine, such as the Wankel rotary engine, has a more attractive power to weight ratio than the normal reciprocating engine. The rotary engine can be treated and evaluated with respect to performance characteristics as a displacement type, four-stroke internal combustion engine, one-cycle similar to the reciprocating engine. For any combustion engine to reach the maximum power output, the mixture formation inside the engine should be considered. The flow phenomenon inside the engine is a key parameter which involves the mixture formation mechanism. This paper investigated the spray characteristic from the injector and the flow phenomena inside the combustion chamber. Its behaviours were studied using computational fluid dynamics simulation. The simulation setup was described in detail, with reference to meshes; initial condition; and boundary condition. Verification of the calculation was also presented. A comparison of the temperature during compression stroke from the analytical calculation and the adiabetic system simulation were also illustrated. Simulation results showed that the speed of the engine provides a proportional effect on the magnitude of air velocity inside the engine, whereas the circulation region can be expanded by increasing the intake pressure during the intake stroke. 9 refs., 1 tab., 13 figs.

[Two simple questions to diagnose post-stroke depression].

Science.gov (United States)

Nolte, C H; Müller-Nordhorn, J; Jungehülsing, G J; Rossnagel, K; Reich, A; Roll, S; Laumeier, I; Beerfelde, D; Willich, S N; Villringer, A

2006-05-01

Many patients develop a depression after having suffered a stroke. Such a Post-Stroke Depression (PSD) impairs rehabilitation and quality of life. PSD is underdiagnosed in spite of available treatment. Several questionnaires have been created to diagnose a PSD. But questionnaires have been considered cumbersome and time-consuming. The aim of this study was to find out whether two simple, standardised questions will identify those stroke patients, who have developed a PSD. The two case-finding questions and the Beck Depression Inventory (BDI) were sent to patients of the Berlin Acute Stroke Study (BASS) four years after their stroke. Incomplete questionnaires were complemented via mail or telephone. Severity of depression was assessed by means of BDI. Out of 211 patients, 199 responded to the questionnaire (94 %). 193 questionnaires were complete (97 %). Forty-two patients affirmed both case-finding questions (22 %). Compared to patients, who did not affirm both questions, these patients had a higher BDI score (19 +/- 8 vs. 7 +/- 5; p two questions were 89 % and 90 %, respectively. The positive and negative predictive value were 60 % and 98 % respectively. The number of confirmed questions (0, 1, 2) correlated well with the BDI score (r (2) = 0.67, p Two standardized questions can identify patients with PSD for further diagnostic evaluation and therapy. Diagnosis of PSD might be facilitated by using them as screening instrument.

Effect of Cylinder Liner Oil Grooves Shape on Two-Stroke Marine Diesel Engine's Piston Ring Friction Force

Directory of Open Access Journals (Sweden)

Salaheldin A. Mohamad

2015-02-01

Full Text Available The dimensions, area densities, and geometry of macroscale surface textures may affect the performance of hydrodynamic lubrication interface. Reported in this paper are the investigations of the effect of surface textures bottom shapes on the friction forces between piston ring and cylinder liner for two-stroke marine diesel engine, using numerically generated textures and average Reynolds equation. These textures are on the cylinder liner surface in the form of circumferential oil grooves with different aspect ratios and different area densities. The hydrodynamic pressure distribution is also calculated using Reynolds boundary condition. The results revealed that the bottom shape could positively affect the friction between moving surfaces, as it could provide a microwedge or microstep bearing that tends to enhance the lubrication condition between piston ring and cylinder liner.

The FLASSH study: protocol for a randomised controlled trial evaluating falls prevention after stroke and two sub-studies

Directory of Open Access Journals (Sweden)

Mackintosh Shylie F

2009-03-01

Full Text Available Abstract Background Falls are common in stroke survivors returning home after rehabilitation, however there is currently a lack of evidence about preventing falls in this population. This paper describes the study protocol for the FLASSH (FaLls prevention After Stroke Survivors return Home project. Methods and design This randomised controlled trial aims to evaluate the effectiveness of a multi-factorial falls prevention program for stroke survivors who are at high risk of falling when they return home after rehabilitation. Intervention will consist of a home exercise program as well as individualised falls prevention and injury minimisation strategies based on identified risk factors for falls. Additionally, two sub-studies will be implemented in order to explore other key areas related to falls in this population. The first of these is a longitudinal study evaluating the relationship between fear of falling, falls and function over twelve months, and the second evaluates residual impairment in gait stability and obstacle crossing twelve months after discharge from rehabilitation. Discussion The results of the FLASSH project will inform falls prevention practice for stroke survivors. If the falls prevention program is shown to be effective, low cost strategies to prevent falls can be implemented for those at risk around the time of discharge from rehabilitation, thus improving safety and quality of life for stroke survivors. The two sub-studies will contribute to the overall understanding and management of falls risk in stroke survivors. Trial registration This trial is registered with the Australian and New Zealand Clinical Trials Registry (ACTRN012607000398404.

Comparative evaluation of a two stroke compressed natural gas mixer design using simulation and experimental techniques

Energy Technology Data Exchange (ETDEWEB)

Ramasamy, D.; Bakar, R.A.; Rahim, M.F.; Noor, M.M. [Malaysia Pahang Univ., Pahang (Malaysia). Automotive Focus Group

2008-07-01

A study was conducted in which a two-stroke engine was converted for use with bi-fuel, notably compressed natural gas and gasoline. The excessive by-products generated by two-stroke engine combustion can be attributed to the inefficient combustion process. This prototype uniflow-type single-cylinder engine was equipped with a bi-fuel conversion system. A dedicated mixer was also developed to meter the gaseous fuel through the engine intake system. It was designed to meet air and fuel requirement similar to its gasoline counterpart. The mixer was modeled to obtain optimum orifice diameter using three different sizes of 14, 16 and 18 mm respectively. A standard computational fluid dynamics (CFD) software package was used to simulate the flow. A pressure reading was obtained during the prototype test. The drop in pressure across the venturi was shown to be an important parameter as it determined the actual fuel-air ratio in the actual engine. A good agreement of CFD outputs with that of the experimental outputs was recorded. The experimental technique validated the pressure distribution predicted by CFD means on the effects of the three insert rings in the CNG mixer. The simulation exercise can be used to predict the amount of CNG consumed by the engine. It was concluded that the 14 mm throat ring was best suited for the CNG mixer because it provided the best suction. Once the mixer is tested on a real engine, it will clear any doubts as to whether the throat can function at high engine speeds. 5 refs., 3 tabs., 8 figs.

Four-Stroke, Internal Combustion Engine Performance Modeling

Science.gov (United States)

Wagner, Richard C.

In this thesis, two models of four-stroke, internal combustion engines are created and compared. The first model predicts the intake and exhaust processes using isentropic flow equations augmented by discharge coefficients. The second model predicts the intake and exhaust processes using a compressible, time-accurate, Quasi-One-Dimensional (Q1D) approach. Both models employ the same heat release and reduced-order modeling of the cylinder charge. Both include friction and cylinder loss models so that the predicted performance values can be compared to measurements. The results indicate that the isentropic-based model neglects important fluid mechanics and returns inaccurate results. The Q1D flow model, combined with the reduced-order model of the cylinder charge, is able to capture the dominant intake and exhaust fluid mechanics and produces results that compare well with measurement. Fluid friction, convective heat transfer, piston ring and skirt friction and temperature-varying specific heats in the working fluids are all shown to be significant factors in engine performance predictions. Charge blowby is shown to play a lesser role.

Modeling the condensation of sulfuric acid and water on the cylinder liner of a large two-stroke marine diesel engine

DEFF Research Database (Denmark)

Cordtz, Rasmus Faurskov; Mayer, Stefan; Eskildsen, Svend S.

2018-01-01

Corrosive wear of cylinder liners in large two-stroke marine diesel engines that burn heavy fuel oil containing sulfur is coupled to the formation of gaseous sulfur trioxide (SO3) and subsequent combined condensation of sulfuric acid (H2SO4) and water (H2O) vapor. The present work seeks to address...... vapor liquid equilibrium. By assuming homogenous cylinder gas mixtures condensation is modeled using a convective heat and mass transfer analogy combined with realistic liner temperature profiles. Condensation of water is significantly altered by the liner temperature and charge air humidity while...... how fuel sulfur content, charge air humidity and liner temperature variations affects the deposition of water and sulfuric acid at low load operation. A phenomenological engine model is applied to simulate the formation of cylinder/bulk gas combustion products and dew points comply with H2O–H2SO4...

Phase-locked stereoscopic PIV measurements of the turbulent swirling flow in a dynamic model of a uniflow-scavenged two-stroke engine cylinder

DEFF Research Database (Denmark)

Ingvorsen, Kristian Mark; Meyer, Knud Erik; Walther, Jens Honore

2013-01-01

It is desirable to use computational fluid dynamics for the optimization of in-cylinder processes in large two-stroke low-speed uniflowscavenged marine diesel engines. However, the complex nature of the turbulent swirling in-cylinder flow necessitates experimental data for validation of the used...... profiles in general will not be representative for the dynamic conditions. The temporal development of the swirl strength is investigated by computing the angular momentum. The swirl strength shows an exponential decay from scavenge port closing to scavenge port opening corresponding to a reduction of 34%....

Experimental Evaluation of a Method for Turbocharging Four-Stroke, Single Cylinder, Internal Combustion Engines

Science.gov (United States)

Buchman, Michael; Winter, Amos

2015-11-01

Turbocharging an engine increases specific power, improves fuel economy, reduces emissions, and lowers cost compared to a naturally aspirated engine of the same power output. These advantages make turbocharging commonplace for multi-cylinder engines. Single cylinder engineers are not commonly turbocharged due to the phase lag between the exhaust stroke, which powers the turbocharger, and the intake stroke, when air is pumped into the engine. Our proposed method of turbocharging single cylinder engines is to add an ``air capacitor'' to the intake manifold, an additional volume that acts as a buffer to store compressed air between the exhaust and intake strokes, and smooth out the pressure pulses from the turbocharger. This talk presents experimental results from a single cylinder, turbocharged diesel engine fit with various sized air capacitors. Power output from the engine was measured using a dynamometer made from a generator, with the electrical power dissipated with resistive heating elements. We found that intake air density increases with capacitor size as theoretically predicted, ranging from 40 to 60 percent depending on heat transfer. Our experiment was able to produce 29 percent more power compared to using natural aspiration. These results validated that an air capacitor and turbocharger may be a simple, cost effective means of increasing the power density of single cylinder engines.

Quality of Life during the First Two Years Post Stroke : The Restore4Stroke Cohort Study

NARCIS (Netherlands)

van Mierlo, Maria L.; van Heugten, Caroline M.; Post, Marcel W. M.; Hajos, Tibor R. S.; Kappelle, L. Jaap; Visser-Meily, Johanna M. A.

2016-01-01

BACKGROUND: Little information is available about the course of quality of life (QoL) post stroke and how dependency on activities of daily living (ADL) influences this course. The aim of this study was therefore to describe the course of QoL from 2 months up to 2 years post stroke and to study the

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

Science.gov (United States)

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

Effects of Scavenging System Configuration on In-Cylinder Air Flow Organization of an Opposed-Piston Two-Stroke Engine

Directory of Open Access Journals (Sweden)

Fukang Ma

2015-06-01

Full Text Available In-cylinder air flow is very important from the point of view of mixture formation and combustion. In this direction, intake chamber structure and piston crown shape play a very crucial role for in-cylinder air pattern of opposed-piston two-stroke (OP2S engines. This study is concerned with the three-dimensional (3D computational fluid dynamics (CFD analysis of in-cylinder air motion coupled with the comparison of predicted results with the zero-dimensional (0D parametric model. Three configurations viz., a flat piston uniform scavenging chamber, a flat piston non-uniform scavenging chamber and a pit piston non-uniform scavenging chamber have been studied. 0D model analysis of in-cylinder air flow is consistent with 3D CFD simulation. It is concluded that a pit piston non-uniform scavenging chamber is the best design from the point of view of tumble ratio, turbulent kinetic energy and turbulent intensity, which play very important roles in imparting proper air motion. Meanwhile a flat piston uniform scavenging chamber can organize a higher swirl ratio and lower tumble ratio which is important to improve the scavenging process.

A New, Highly Improved Two-Cycle Engine

Science.gov (United States)

Wiesen, Bernard

2008-01-01

The figure presents a cross-sectional view of a supercharged, variable-compression, two-cycle, internal-combustion engine that offers significant advantages over prior such engines. The improvements are embodied in a combination of design changes that contribute synergistically to improvements in performance and economy. Although the combination of design changes and the principles underlying them are complex, one of the main effects of the changes on the overall engine design is reduced (relative to prior two-cycle designs) mechanical complexity, which translates directly to reduced manufacturing cost and increased reliability. Other benefits include increases in the efficiency of both scavenging and supercharging. The improvements retain the simplicity and other advantages of two-cycle engines while affording increases in volumetric efficiency and performance across a wide range of operating conditions that, heretofore have been accessible to four-cycle engines but not to conventionally scavenged two-cycle ones, thereby increasing the range of usefulness of the two-cycle engine into all areas now dominated by the four-cycle engine. The design changes and benefits are too numerous to describe here in detail, but it is possible to summarize the major improvements: Reciprocating Shuttle Inlet Valve The entire reciprocating shuttle inlet valve and its operating gear is constructed as a single member. The shuttle valve is actuated in a lost-motion arrangement in which, at the ends of its stroke, projections on the shuttle valve come to rest against abutments at the ends of grooves in a piston skirt. This shuttle-valve design obviates the customary complex valve mechanism, actuated from an engine crankshaft or camshaft, yet it is effective with every type of two-cycle engine, from small high-speed single cylinder model engines, to large low-speed multiple cylinder engines.

Risk and mortality of traumatic brain injury in stroke patients: two nationwide cohort studies.

Science.gov (United States)

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 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.

Turbulent swirling flow in a dynamic model of a uniflow-scavenged two-stroke engine

Science.gov (United States)

Ingvorsen, K. M.; Meyer, K. E.; Walther, J. H.; Mayer, S.

2014-06-01

It is desirable to use computational fluid dynamics for optimization of the in-cylinder processes in low-speed two-stroke uniflow-scavenged marine diesel engines. However, the complex nature of the turbulent swirling in-cylinder flow necessitates experimental data for validation of the used turbulence models. In the present work, the flow in a dynamic scale model of a uniflow-scavenged cylinder is investigated experimentally. The model has a transparent cylinder and a moving piston driven by a linear motor. The flow is investigated using phase-locked stereoscopic particle image velocimetry (PIV) and time-resolved laser Doppler anemometry (LDA). Radial profiles of the phase-locked mean and rms velocities are computed from the velocity fields recorded with PIV, and the accuracy of the obtained profiles is demonstrated by comparison with reference LDA measurements. Measurements are carried out at five axial positions for 15 different times during the engine cycle and show the temporal and spatial development of the swirling in-cylinder flow. The tangential velocity profiles in the bottom of the cylinder near the end of the scavenge process are characterized by a concentrated swirl resulting in wake-like axial velocity profiles and the occurrence of a vortex breakdown. After scavenge port closing, the axial velocity profiles indicate that large transient swirl-induced structures exist in the cylinder. Comparison with profiles obtained under steady-flow conditions shows that the scavenge flow cannot be assumed to be quasi-steady. The temporal development of the swirl strength is investigated by computing the angular momentum. The swirl strength shows an exponential decay from scavenge port closing to scavenge port opening corresponding to a reduction of 34 %, which is in good agreement with theoretical predictions.

Industrial Education. "Small Engines".

Science.gov (United States)

Parma City School District, OH.

Part of a series of curriculum guides dealing with industrial education in junior high schools, this guide provides the student with information and manipulative experiences on small gasoline engines. Included are sections on shop adjustment, safety, small engines, internal combustion, engine construction, four stroke engines, two stroke engines,…

Thermal balance of a LPG fuelled, four stroke SI engine with water addition

International Nuclear Information System (INIS)

Ozcan, Hakan; Soeylemez, M.S.

2006-01-01

The effect of water injection on a spark ignition engine thermal balance and performance has been experimentally investigated. A four stroke, four cylinder conventional engine was used with LPG (liquid petroleum gas) as fuel. Different water to fuel ratios by mass were used with variable engine speed ranging from 1000 to 4500 rpm. The results showed that as the water injection level to the engine increased, the percentage of useful work increased, while the losses other than unaccounted losses decreased. Additionally, the specific fuel consumption decreases, while the engine thermal efficiency increases. The average increase in the brake thermal efficiency for a 0.5 water to fuel mass ratio is approximately 2.7% over the use of LPG alone for the engine speed range studied

Independently variable phase and stroke control for a double acting Stirling engine

Science.gov (United States)

Berchowitz, David M.

1983-01-01

A phase and stroke control apparatus for the pistons of a Stirling engine includes a ring on the end of each piston rod in which a pair of eccentrics is arranged in series, torque transmitting relationship. The outer eccentric is rotatably mounted in the ring and is rotated by the orbiting ring; the inner eccentric is mounted on an output shaft. The two eccentrics are mounted for rotation together within the ring during normal operation. A device is provided for rotating one eccentric with respect to another to change the effective eccentricity of the pair of eccentrics. A separately controlled phase adjustment is provided to null the phase change introduced by the change in the orientation of the outer eccentric, and also to enable the phase of the pistons to be changed independently of the stroke change.

A CFD parametric study on the performance of a low-temperature-differential γ-type Stirling engine

International Nuclear Information System (INIS)

Chen, Wen-Lih; Yang, Yu-Ching; Salazar, Jose Leon

2015-01-01

Highlights: • A parametric study on a low-temperature-differential Stirling engine has been conducted by using CFD. • The effects of three geometric and two operational parameters on engine performance have been investigated. • It is found that each parameter produces different effects except power piston stroke and power piston radius. • The results are useful for guiding the design of new low-temperature-differential Stirling engines. - Abstract: An in-house CFD code has been applied to a low-temperature-differential (LTD) γ-type Stirling engine to understand the effects posed by several geometrical and operational parameters on engine performance. The results include variations of pressure, temperature, and heat transfer rates within an engine cycle as well as variations of engine’s power and efficiency versus these parameters. It is found that power piston stroke and radius influence engine performance very similarly, and power and efficiency both increase as these two parameters increase. In fact, the effects of the two parameters can be assimilated into those by the parameter of compression ratio. The stroke of displacer is observed to affect strongly on heat input but weakly on power, thus causing the efficiency to decrease as it increases. As expected, both power and efficiency increase as temperature difference between the hot and cold ends increases. Lastly, engine speed is observed to pose strong positive effects on power but exert weak effects on efficiency. This study reveals the effects produced by several important parameters on engine performance, and such information is very useful for the design of new LTD Stirling engines.

Influence of piston position on the scavenging and swirling flow in two-stoke diesel engines

DEFF Research Database (Denmark)

Obeidat, Anas; Haider, Sajjad; Meyer, Knud Erik

2011-01-01

We study the eect of piston position on the in-cylinder swirling flow in a low speed large two-stroke marine diesel engine model. We are using Large Eddy Simulations in OpenFOAM, with three different models for the turbulent flow: a one equation model (OEM), a dynamic one equation model (DOEM...

Methods to improve efficiency of four stroke, spark ignition engines at part load

International Nuclear Information System (INIS)

Kutlar, Osman Akin; Arslan, Hikmet; Calik, Alper Tolga

2005-01-01

The four stroke, spark ignition (SI) engine pressure-volume diagram (p-V) contains two main parts. They are the compression-combustion-expansion (high pressure loop) and the exhaust-intake (low pressure or gas exchange loop) parts. The main reason for efficiency decrease at part load conditions for these types of engines is the flow restriction at the cross sectional area of the intake system by partially closing the throttle valve, which leads to increased pumping losses and to increased low pressure loop area on the p-V diagram. Meanwhile, the poorer combustion quality, i.e. lower combustion speed and cycle to cycle variations, additionally influence these pressure loop areas. In this study, methods for increasing efficiency at part load conditions and their potential for practical use are investigated. The study also includes a review of the vast literature on the solution of this problem. This investigation shows that the potential for increasing the efficiency of SI engines at part load conditions is not yet exhausted. Each method has its own advantages and disadvantages. Among these, the most promising methods to decrease the fuel consumption at part load conditions are stratified charge and variable displacement engines. When used in combination, the other listed methods are more effective than their usage alone

EVALUATION OF POLLUTANT EMISSIONS FROM TWO-STROKE MARINE DIESEL ENGINE FUELED WITH BIODIESEL PRODUCED FROM VARIOUS WASTE OILS AND DIESEL BLENDS

Directory of Open Access Journals (Sweden)

Danilo Nikolić

2016-12-01

Full Text Available Shipping represents a significant source of diesel emissions, which affects global climate, air quality and human health. As a solution to this problem, biodiesel could be used as marine fuel, which could help in reducing the negative impact of shipping on environment and achieve lower carbon intensity in the sector. In Southern Europe, some oily wastes, such as wastes from olive oil production and used frying oils could be utilized for production of the second-generation biodiesel. The present research investigates the influence of the second-generation biodiesel on the characteristics of gaseous emissions of NOx, SO2, and CO from marine diesel engines. The marine diesel engine that was used, installed aboard a ship, was a reversible low-speed two-stroke engine, without any after-treatment devices installed or engine control technology for reducing pollutant emission. Tests were carried out on three regimes of engine speeds, 150 rpm, 180 rpm and 210 rpm under heavy propeller condition, while the ship was berthed in the harbor. The engine was fueled by diesel fuel and blends containing 7% and 20% v/v of three types of second-generation biodiesel made of olive husk oil, waste frying sunflower oil, and waste frying palm oil. A base-catalyzed transesterification was implemented for biodiesel production. According to the results, there are trends of NOx, SO2, and CO emission reduction when using blended fuels. Biodiesel made of olive husk oil showed better gaseous emission performances than biodiesel made from waste frying oils.

Optimal control of the power adiabatic stroke of an optomechanical heat engine.

Science.gov (United States)

Bathaee, M; Bahrampour, A R

2016-08-01

We consider the power adiabatic stroke of the Otto optomechanical heat engine introduced in Phys. Rev. Lett. 112, 150602 (2014)PRLTAO0031-900710.1103/PhysRevLett.112.150602. We derive the maximum extractable work of both optomechanical normal modes in the minimum time while the system experiences quantum friction effects. We show that the total work done by the system in the power adiabatic stroke is optimized by a bang-bang control. The time duration of the power adiabatic stroke is of the order of the inverse of the effective optomechanical-coupling coefficient. The optimal phase-space trajectory of the Otto cycle for both optomechanical normal modes is also obtained.

Experimental Study of Using Emulsified Diesel Fuel on the Performance and Pollutants Emitted from Four Stroke Water Cooled Diesel Engine

Science.gov (United States)

Sakhrieh, A.; Fouad, R. H.; Yamin, J. A.

2009-08-01

A water-cooled, four stroke, four cylinder, direct injection diesel engine was used to study the effect of emulsified diesel fuel on the engine performance and on the main pollutant emissions. Emulsified diesel fuels of 0%, 5%, 10%, 15%, 20%, 25% and 30% water by volume were used. The experiments were conducted in the speed range from 1000 to 3000 rpm. It was found that, in general, using emulsified fuel improves the engine performance and reduces emissions. While the BSFC has a minimum value at 5% water and 2000 rpm, the torque, the BMEP and efficiency are found to have maximum values under these conditions. CO2 was found to increase with engine speed and to decrease with water content. NOx produced from emulsified fuel is significantly less than that produced from pure diesel under the same conditions.

Performance study of a four-stroke spark ignition engine working with both of hydrogen and ethyl alcohol as supplementary fuel

Energy Technology Data Exchange (ETDEWEB)

Al-Baghdadi, M.A.-R.S. [Babylon Univ. (Iraq). Dept. of Mechanical Engineering

2000-10-01

The effect of the amount of hydrogen/ethyl alcohol addition on the performance and pollutant emission of a four-stroke spark ignition engine has been studied. The results of the study show that all engine performance parameters have been improved when operating the gasoline spark ignition engine with dual addition of hydrogen and ethyl alcohol. The important improvements of alcohol addition are to reduce the NO{sub x} emission with increase in the higher useful compression ratio and output power of hydrogen-supplemented engine. The addition of 8 mass% of hydrogen, with 30 vol% of ethyl alcohol into a gasoline engine operating at 9 compression ratio and 1500 rpm causes a 48.5% reduction in CO emission, 31.1% reduction in NO{sub x} emission and 58.5% reduction in specific fuel consumption. Moreover, the engine thermal efficiency and output power increased by 10.1 and 4.72%, respectively. When ethyl alcohol is increased over 30%, it causes unstable engine operation which can be related to the fact that the fuel is not vaporized, and this causes a reduction in both the break power and efficiency. (Author)

Performance study of four stroke S.I. engine using upgraded biogas fuel

Directory of Open Access Journals (Sweden)

Jai Prakash

2016-09-01

Full Text Available In resent year, increased environmental awareness and energy shortages have encouraged researchers to investigate the possibility of using alternate fuels. The purpose of finding the alternate sources is to minimize the consumption of conventional fossil fuels and in turn to reduce the degradation of environmental quality to a great extent. The use of bio-based fuels like biogas produced from biomass and bio-wastes is a valuable energy source which is sustainable that can be manufactured from locally available waste streams thereby solving the local waste problem. Local wastes (organic wastes contain enough energy to contribute significantly to energy supply especially the rural regions of developing countries. Biogas is a clean and environment friendly fuel produced from anaerobic digestion of agro, animal or human wastes. The biogas has about 60 % methane and 40 % carbon dioxide with small traces of H2S. The use of H2S leads to formation of SO2 which combines with the water vapor to form acids and hence corrode the metals. Thus, raw biogas as such cannot be used for powering vehicular I.C engine. In the present work, an attempt has been made to upgrade the quality of raw biogas by removing CO2 and H2S, thus enriching its methane content up to the natural gas level and to study the performance of four stroke S.I engine aspirating upgraded biogas as primary fuel and its emission characteristics.

Numerical analysis of airflow cyclic variation during intake and compression process in a 4-stroke engine

International Nuclear Information System (INIS)

Fadzi, M.A.; Zakaria, S.; Yusoff, M.Z; Yusaf, T.

2004-01-01

A degree of turbulence is one of the main factors that used to optimize the combustion efficiency, the specific fuel consumption and emissions in automotive engines. A 3D numerical study was prepared to evaluate how the complex geometry of a dome-roof and a pent-roof engine influences the flow field. A 4-stroke, 100cc SI motorcycle engine was used as the model. Engines operating at 1000 rpm and fixed atmospheric conditions were simulated using a commercial computational fluid dynamics (CFD) solver Star CD for cold flow simulations for both induction and compression stroke. Post processing stage was used to observe the cyclic airflows. The simulated results were utilized to compare aerodynamic characteristic in term of swirl and tumble motion. Variations of airflow in the cylinder were viewed through different specific geometry of both combustion chambers. Numerical results show that higher swirl was generated in the dome-roof shape. Results from Star CD simulations were translated into numerical data to compare the value of swirl ratio for both pent-roof and dome-roof engine. Remarkable insights are gained into how the chamber geometry can influence homogeneity of gas mixtures and indirectly affect the efficiency of an engine. (author)

U.S. Coast Guard pollution abatement program - Two-stroke cycle outboard engine emissions

Science.gov (United States)

1975-09-01

This report documents the results of emissions tests performed on three old and two new outboard engines. Tests of the emissions were made before and after water contact. Older engines were tested in as-received condition, tuned to factory specificat...

A Comparison of Different Engineering Models for Computation of Lightning Magnetic Field of Negative First Strokes

Directory of Open Access Journals (Sweden)

V. Javor

2012-11-01

Full Text Available A comparison of different engineering models results for a lightning magnetic field of negative first strokes is presented in this paper. A new function for representing double-peaked channel-base current is used for lightning stroke modeling. This function includes the initial and subsidiary peak in a current waveform. For experimentally measured currents, a magnetic field is calculated for the three engineering models: transmission line (TL model, TL model with linear decay (MTLL, and TL model with exponential decay (MTLE.

Validation of a reduced chemical mechanism coupled to CFD model in a 2-stroke HCCI engine

NARCIS (Netherlands)

Izadi Najafabadi, M.; Somers, B.; Nuraini, A.

2015-01-01

Homogeneous Charge Compression Ignition (HCCI) combustion technology has demonstrated a profound potential to decrease both emissions and fuel consumption. In this way, the significance of the 2-stroke HCCI engine has been underestimated as it can provide more power stroke in comparison to a

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

Science.gov (United States)

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.

An investigation of fluid flow during induction stroke of a water analog model of an IC engine using an innovative optical velocimetry concept: LIPA

Science.gov (United States)

Stier, Bernd; Falco, R. E.

1994-01-01

Optical measurements on an axisymmetrical quartz component engine research model were made to evaluate the flow field encountered during induction. The measurement technique is LIPA (Laser Induced Photochemical Anemometry), a non-intrusive velocimetry concept that provides an investigator of fluid flow with a tool to attain planar information about three-dimensional velocity and vorticity vectors in a single measurement step. The goal of this investigation is to further develop this measurement technique and apply it to study the induction stroke of a water analog model of a four-stroke internal combustion engine. The research conducted in the water analog model is a fundamental scientific inquiry into the flow fields that develop in the induction stroke of an engine at idling engine speeds. As this is the first investigation of its kind using LIPA technique, our goal has been to quantify, in a preliminary manner, the flow field features that develop during the intake stroke. In the process a more comprehensive understanding of the flow field features was developed, and tied to the quantification. The study evaluated the flow field of the intake stroke by estimating fields of velocity and vorticity. On the basis of these data, information about fluid dynamics during induction at engine speeds of 10, 20, and 30 RPM (corresponding to 170, 340, and 510 RPM respectively, when air is the flowing medium) for three different valve lifts was obtained. The overall development of the flow field, its energy content (kinetic, fluctuation) for the different settings of the engine parameters, vorticity information, and cyclic variations have been quantified. These have been discussed in terms of mixing performance.

Increasing the volumetric efficiency of Diesel engines by intake pipes

Science.gov (United States)

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.

Investigation of ecological parameters of four-stroke SI engine, with pneumatic fuel injection system

Science.gov (United States)

Marek, W.; Śliwiński, K.

2016-09-01

The publication presents the results of tests to determine the impact of using waste fuels, alcohol, to power the engine, on the ecological parameters of the combustion engine. Alternatively fuelled with a mixture of iso- and n-butanol, indicated with "X" and "END, and gasoline and a mixture of fuel and alcohol. The object of the study was a four-stroke engine with spark ignition designed to work with a generator. Motor power was held by the modified system of pneumatic injection using hot exhaust gases developed by Prof. Stanislaw Jarnuszkiewicz, controlled by modern mechatronic systems. Tests were conducted at a constant speed for the intended use of the engine. The subject of the research was to determine the control parameters such as ignition timing, mixture composition and the degree of exhaust gas recirculation on the ecological parameters of the engine. Tests were carried out using partially quality power control. In summary we present the findings of this phase of the study.

Improvement of performance and reduction of pollutant emission of a four stroke spark ignition engine fueled with hydrogen-gasoline fuel mixture

Energy Technology Data Exchange (ETDEWEB)

Al-Baghdadi, Maher Abdul-Resul Sadiq; Al-Janabi, Haroun Abdul-Kadim Shahad [Babylon Univ., Dept. of Mechanical Engineering, Babylon (Iraq)

2000-07-01

The effect of the amount of hydrogen/ethyl alcohol addition on the performance and pollutant emissions of a four stroke spark ignition engine has been studied. A detailed model to simulate a four stroke cycle of a spark ignition engine fueled with hydrogen-ethyl alcohol-gasoline has been used to study the effect of hydrogen and ethyl alcohol blending on the thermodynamic cycle of the engine. The results of the study show that all engine performance parameters have been improved when operating the gasoline S.I.E. with dual addition of hydrogen and ethyl alcohol. It has been found that 4% of hydrogen and 30% of ethyl alcohol blending causes a 49% reduction in CO emission, a 39% reduction in NO{sub x} emission, a 49% reduction in specific fuel consumption and increases in the thermal efficiency and output power by 5 and 4%, respectively. When ethyl alcohol is increased over 30%, it causes unstable engine operation which can be related to the fact that the fuel is not vaporised, and this causes a reduction in both the brake power and efficiency. (Author)

A unified engineering model of the first stroke in downward negative lightning

Science.gov (United States)

Nag, Amitabh; Rakov, Vladimir A.

2016-03-01

Each stroke in a negative cloud-to-ground lightning flash is composed of downward leader and upward return stroke processes, which are usually modeled individually. The first stroke leader is stepped and starts with preliminary breakdown (PB) which is often viewed as a separate process. We present the first unified engineering model for computing the electric field produced by a sequence of PB, stepped leader, and return stroke processes, serving to transport negative charge to ground. We assume that a negatively charged channel extends downward in a stepped fashion during both the PB and leader stages. Each step involves a current wave that propagates upward along the newly formed channel section. Once the leader attaches to ground, an upward propagating return stroke neutralizes the charge deposited along the channel. Model-predicted electric fields are in reasonably good agreement with simultaneous measurements at both near (hundreds of meters, electrostatic field component is dominant) and far (tens of kilometers, radiation field component is dominant) distances from the lightning channel. Relations between the features of computed electric field waveforms and model input parameters are examined. It appears that peak currents associated with PB pulses are similar to return stroke peak currents, and the observed variation of electric radiation field peaks produced by leader steps at different heights above ground is influenced by the ground corona space charge.

Ischemic stroke in paediatrics - narrative review of the literature and two cases.

Science.gov (United States)

Klucka, Jozef; Stourac, Petr; Stoudek, Roman; Toukalkova, Michaela; Harazim, Hana; Kosinova, Martina; Stouracova, Alena; Mrlian, Andrej; Suk, Petr; Malaska, Jan

2017-03-01

Stroke is a rare condition in childhood with an estimated incidence of between 1.3-13/100.000 patients. Clinical manifestation and risk factors for paediatric stroke are different from those of adults. The uncommon incidence, age-associated difference and plethora of clinical symptoms make the diagnosis of such strokes extremely difficult and often delayed. The history and clinical examination should point to diseases or predisposing factors. Neuroimaging (DWI MR) is the golden standard for diagnosis of paediatric stroke and other investigations can be considered according to the clinical condition. Despite advances in paediatric stroke research and clinical care, questions remain unanswered regarding acute treatment, secondary prevention and rehabilitation. The treatment recommendations are mainly extrapolated from studies on adult populations. In the review authors summarized the clinical characteristics and diagnostic steps for stroke in children/adolescents based on the most recent international guidelines and practical directions for recognising and managing the child/adolescent with stroke in paediatric emergency. In the two case reports, we describe the clinical course in both stroke patients.

Wheels, Cranks, and Cams: An Animated Spreadsheet-Based Mathematical Model of a Four-Stroke Engine.

Science.gov (United States)

Callender, J. T.; Jackson, R.

1998-01-01

Analyzes the mathematics of rotational and translational motion and how one can influence the other in the context of cams and cranks. Describes how the individual components can be brought together to simulate a four-stroke engine and how the engine animates again using the same simple macro. (Author/ASK)

Validation of a zero-dimensional model for prediction of NOx and engine performance for electronically controlled marine two-stroke diesel engines

DEFF Research Database (Denmark)

Scappin, Fabio; Stefansson, Sigurður H.; Haglind, Fredrik

2012-01-01

The aim of this paper is to derive a methodology suitable for energy system analysis for predicting the performance and NOx emissions of marine low speed diesel engines. The paper describes a zero-dimensional model, evaluating the engine performance by means of an energy balance and a two zone...... experimental data from two MAN B&W engines; one case being data subject to engine parameter changes corresponding to simulating an electronically controlled engine; the second case providing data covering almost all model input and output parameters. The first case of validation suggests that the model can...

Liquid sprays and flow studies in the direct-injection diesel engine under motored conditions

Science.gov (United States)

Nguyen, Hung Lee; Carpenter, Mark H.; Ramos, Juan I.; Schock, Harold J.; Stegeman, James D.

1988-01-01

A two dimensional, implicit finite difference method of the control volume variety, a two equation model of turbulence, and a discrete droplet model were used to study the flow field, turbulence levels, fuel penetration, vaporization, and mixing in diesel engine environments. The model was also used to study the effects of engine speed, injection angle, spray cone angle, droplet distribution, and intake swirl angle on the flow field, spray penetration and vaporization, and turbulence in motored two-stroke diesel engines. It is shown that there are optimum conditions for injection, which depend on droplet distribution, swirl, spray cone angle, and injection angle. The optimum conditions result in good spray penetration and vaporization and in good fuel mixing. The calculation presented clearly indicates that internal combustion engine models can be used to assess, at least qualitatively, the effects of injection characteristics and engine operating conditions on the flow field and on the spray penetration and vaporization in diesel engines.

Mathematical modeling of a four-stroke resonant engine for micro and mesoscale applications

Science.gov (United States)

Preetham, B. S.; Anderson, M.; Richards, C.

2014-12-01

In order to mitigate frictional and leakage losses in small scale engines, a compliant engine design is proposed in which the piston in cylinder arrangement is replaced by a flexible cavity. A physics-based nonlinear lumped-parameter model is derived to predict the performance of a prototype engine. The model showed that the engine performance depends on input parameters, such as heat input, heat loss, and load on the engine. A sample simulation for a reference engine with octane fuel/air ratio of 0.043 resulted in an indicated thermal efficiency of 41.2%. For a fixed fuel/air ratio, higher output power is obtained for smaller loads and vice-versa. The heat loss from the engine and the work done on the engine during the intake stroke are found to decrease the indicated thermal efficiency. The ratio of friction work to indicated work in the prototype engine is about 8%, which is smaller in comparison to the traditional reciprocating engines.

Fuel Effects on Emissions From Non-Road Engines

Energy Technology Data Exchange (ETDEWEB)

Murtonen, T.; Nylund, N.

2003-10-15

The objective of this project was to study how fuel quality affects the exhaust emissions from different kinds of non-road engines. The project was divided into two parts: emissions from small gasoline engines and emissions from diesel engines. The measured small engines were a 2-stroke chainsaw engine, and a 4-stroke OHV engine, which could be used in different applications. Measurements were done with three different fuels, with and without catalyst. Also a comparison between biodegradable vs. conventional lubrication oil was done with the 2-stroke engine. Measurements were done according to ISO8178 standard. The results clearly demonstrate that using a good quality fuel (e.g. low sulphur, low aromatics) and a catalyst gives the best outcome in overall emission levels from these small engines. In the second part two different diesel engines were tested with five different fuels. Two of the fuels were biodiesel blends. The engines were chosen to represent old and new engine technology. The old engine (MY 1985) was produced before EU emission regulations were in place, and the new engine fulfilled the current EU Stage 2 emission limits. These measurements were also done according to the ISO8178 standard. With the new engine comparison with and without oxidation catalyst was done using two fuels. The results in general are similar compared to the results from the small gasoline engines: fuel quality has an effect on the emissions and when combining a good quality fuel (e.g. low sulphur, low aromatics) and an oxidation catalyst the emission levels are significantly reduced. Also some unregulated emission measurements were done but those results are not included to this report.

External validity of post-stroke interventional gait rehabilitation studies.

Science.gov (United States)

Kafri, Michal; Dickstein, Ruth

2017-01-01

Gait rehabilitation is a major component of stroke rehabilitation, and is supported by extensive research. The objective of this review was to examine the external validity of intervention studies aimed at improving gait in individuals post-stroke. To that end, two aspects of these studies were assessed: subjects' exclusion criteria and the ecological validity of the intervention, as manifested by the intervention's technological complexity and delivery setting. Additionally, we examined whether the target population as inferred from the titles/abstracts is broader than the population actually represented by the reported samples. We systematically researched PubMed for intervention studies to improve gait post-stroke, working backwards from the beginning of 2014. Exclusion criteria, the technological complexity of the intervention (defined as either elaborate or simple), setting, and description of the target population in the titles/abstracts were recorded. Fifty-two studies were reviewed. The samples were exclusive, with recurrent stroke, co-morbidities, cognitive status, walking level, and residency being major reasons for exclusion. In one half of the studies, the intervention was elaborate. Descriptions of participants in the title/abstract in almost one half of the studies included only the diagnosis (stroke or comparable terms) and its stage (acute, subacute, and chronic). The external validity of a substantial number of intervention studies about rehabilitation of gait post-stroke appears to be limited by exclusivity of the samples as well as by deficiencies in ecological validity of the interventions. These limitations are not accurately reflected in the titles or abstracts of the studies.

A study of the Armstrong Whitworth swing beam engine for automotive application

Science.gov (United States)

1983-01-01

The introduction of ceramics to those parts suffering high thermal loading was successfully demonstrated, and there is no question that the 100 kw (134 hp) naturally aspirated engine of the future will be developed to produce up to 300 kw (402 hp) by the application of turbocharging or its equivalent. However, at the 60 - 80 kw (80 - 107 hp) size needed for the economic automotive engine, scaling down the 300 kw (402 hp) is beset by the laws of scale. The conventional four stroke diesel was not shown to be successful at the small high speed engine size. The opposed piston two stroke engine does not suffer the same laws of scale and engines in the low power range have already been marketed successfully. The half liter/cylinder Armstrong Whitworth Swing Beam Engine is the latest to be designed with the automotive market in mind. Its low noise structure and balanced linkage system coupled with advantages for easy start and potential use of low grade fuels, derived from its variable compression ratio and slow piston motion, qualifies it for the application.

Automotive Engines; Automotive Mechanics I: 9043.03.

Science.gov (United States)

Dade County Public Schools, Miami, FL.

This automotive engines course studies and demonstrates the theory and principles of operation of the automotive four stroke cycle engine. The student will develop an understanding of the systems necessary to make the engine perform as designed, such as cooling, fuel, ignition and lubrication. This is a one or two quinmester credit course of 45…

A study of operating parameters on the linear spark ignition engine

International Nuclear Information System (INIS)

Lim, Ocktaeck; Hung, Nguyen Ba; Oh, Seokyoung; Kim, Gangchul; Song, Hanho; Iida, Norimasa

2015-01-01

Highlights: • An experimental and simulation study of a linear engine is conducted. • The effects of operating parameters on the generating power are investigated. • The air gap length has a significant influence on the generating power. • The generating power of the linear engine is optimized with the value of 111.3 W. • There are no problems for the linear engine after 100 h of durable test. - Abstract: In this paper, we present our experiment and simulation study of a free piston linear engine based on operating conditions and structure of the linear engine for generating electric power. The free piston linear engine includes a two-stroke free piston engine, linear generators, and compressors. In the experimental study, the effects of key parameters such as input caloric value, equivalence ratio, spark timing delay, electrical resistance, and air gap length on the piston dynamics and electric power output are investigated. Propane is used as a fuel in the free piston linear engine, and it is premixed with the air to make a homogeneous charge before go into the cylinder. The air and fuel mass flow rate are varied by a mass flow controller. The experimental results show that the maximum generating power is found with the value of 111 W at the input caloric value of 5.88 kJ/s, spark timing delay of 1.5 ms, equivalence ratio of 1.0, electric resistance of 30 Ω, and air gap length of 1.0 mm. In order to check the durability of the linear engine, a durable test is conducted during 100 h. The experimental results show that there are no problems for the linear engine after about one hundred hours of the durable test. Beside experimental study, a simulation study is conducted to predict operating behavior of the linear engine. In the simulation study, the two-stroke free piston linear engine is modeled and simulated through a combination of three mathematical models including a dynamic model, a linear alternator model and a thermodynamic model. These

Modeling for Friction of Four Stroke Four Cylinder In-Line Petrol Engine

Directory of Open Access Journals (Sweden)

P.C. Mishra

2013-09-01

Full Text Available A four stroke four cylinder in-line petrol engine is modeled to estimate various performance parameters. The solution is based on tribology and dynamics principle. The detailed parameters relating to engine friction and lubrication are computed numerically for the engine firing order 1-3-4-2. The numerical method is based on finite difference method that solves coupled Reynolds Equation and Energy Equation. Output includes the movie thickness, friction force, friction power loss and temperature rise in the ring liner conjunction in all four cylinders. Transient regime of ring liner lubrication isaddressed while the same changes from hydrodynamic to mixed in an engine cycle. Momentary cessation near the top and bottom dead center that causes boundary interaction is analyzed through asperity contact. The non - Newtonian behavior of lubricant film due to pressure and temperature is addresses using viscosity -pressure- temperature inter relationship.

Production of syngas and oil at biomass refinery and their application in low speed two stroke engines for combined cycle electric energy generation

Energy Technology Data Exchange (ETDEWEB)

Pinatti, Daltro Garcia [Universidade do Sul de Santa Catarina (UNISUL), Tubarao, SC (Brazil)], E-mail: pinatti@demar.eel.usp.br; Oliveira, Isaias de; Ferreira, Joao Carlos; Romao, Erica Leonor [RM Materiais Refratarios Ltd., Lorena, SP (Brazil)], Emails: isaias@rm-gpc.com.br, joaocarlos@rm-gpc.com.br, ericaromao@rm-gpc.com.br; Conte, Rosa Ana [University of Sao Paulo (DEMAR/EEL/USP), SP (Brazil). Lorena School of Engineering. Dept. of Materials Engineering], E-mail: rosaconte@demar.eel.usp.br

2009-07-01

Low speed two stroke engines burn fuels of medium quality with high efficiency (47%) and allows a flexible use of oil (> 8% of total power) and syngas (< 92%, low heating value-LHV>11.2MJ/m{sup 3}). Biomass refinery (BR) generates oil from sludge and oleaginous biomass by low temperature conversion and syngas from lignocellulosic biomass treated by diluted acidic prehydrolysis. BR has low investment cost (US$1,500.00/kW) compared with hydroelectric plants (US$2,500.00/kW) and both generate electric energy with sales price below US$75.00/MWh. It allows distributed generation from 30 MW up to 170 MW or centralized power of 1 GW with six motor generator sets. BR matrix, mass and energy balance, fuels compositions, modulations and scope of supply will be presented. Besides electric energy BR can be tailored to supply other products such as ethanol, H{sub 2} for fuel cells, biodiesel, fertilizer recycling, char and simultaneously maximizes the production of animal protein. (author)

Heat Transfer in Two-Stroke Diesel Engines for Large Ship Propulsion

DEFF Research Database (Denmark)

Christiansen, Caspar Ask

Demands on reducing the fuel consumption and harmful emissions from the compression ignition engines (diesel engines) have been continuously increasing in recent years. To comply with this, better modeling tools for the diesel combustion process are desired from the engine developers. A very......%, 30% and 50% load) was performed on a MAN Diesel & Turbo SE test engine, which shows very promising results for further investigations of dynamic temperature and heat flux in large bore engines. Instantaneous heat flux is derived using both an analytical and a numerical model and compared. More...... was investigated by computer simulations using a 3-D numerical finite volume model made in STAR-CD. General trends are observed from the temperature measurements in the limited part load range. These include among others: local increase in mean surface temperature and mean surface heat flux with increasing load...

STROKE IN YOUNG ADULTS: A RETROSPECTIVE STUDY OF 68 CASES

Directory of Open Access Journals (Sweden)

M. H. Harirchian

2006-06-01

Full Text Available Numerous etiologies are responsible for cases of stroke in young adults. This study reviews the causes of two types of stroke (ischemic and intracerebral hemorrhage in young adults aged 15 to 40years, admitted to our center (a tertiary care center from 1997 to 2002. The purpose of this study is to determine the relative frequency of causes of stroke in young adults and compare this with published data in the literature. Using the codes 46.0 to 46.8 of the International Classification of Diseases- 10th Edition (ICD-10, cases were identified from the records of the stroke patients admitted in Imam Khomeini Hospital and the data were collected from their files using a comprehensive questionnaire. Forty-two cases of ischemic stroke (62% and 26 cases of intracerebral hemorrhage (38% were identified. The leading cause of ischemic stroke was cardioembolism (38.1%, followed by atherosclerosis in 5 cases (11.9%. Among cardiac causes infarction was attributable to consequences of rheumatic heart disease in 8 cases. In 3 cases a cessation or decrease in dose of warfarin was followed directly by an ischemic stroke. The most leading cause of intracerebral hemorrhage was hypertension (30.8%. Other causes were anticoagulant therapy, intratumoral hemorrhage, aplastic anemia, leukemia, arteriovenous malformations, and chronic active hepatitis. In conclusion, cardioembolism and hypertension were the most leading causes of ischemic and hemorrhagic stroke in young adults admitted in our hospital.

Stroke-induced immunodepression and dysphagia independently predict stroke-associated pneumonia - The PREDICT study.

Science.gov (United States)

Hoffmann, Sarah; Harms, Hendrik; Ulm, Lena; Nabavi, Darius G; Mackert, Bruno-Marcel; Schmehl, Ingo; Jungehulsing, Gerhard J; Montaner, Joan; Bustamante, Alejandro; Hermans, Marcella; Hamilton, Frank; Göhler, Jos; Malzahn, Uwe; Malsch, Carolin; Heuschmann, Peter U; Meisel, Christian; Meisel, Andreas

2017-12-01

Stroke-associated pneumonia is a frequent complication after stroke associated with poor outcome. Dysphagia is a known risk factor for stroke-associated pneumonia but accumulating evidence suggests that stroke induces an immunodepressive state increasing susceptibility for stroke-associated pneumonia. We aimed to confirm that stroke-induced immunodepression syndrome is associated with stroke-associated pneumonia independently from dysphagia by investigating the predictive properties of monocytic HLA-DR expression as a marker of immunodepression as well as biomarkers for inflammation (interleukin-6) and infection (lipopolysaccharide-binding protein). This was a prospective, multicenter study with 11 study sites in Germany and Spain, including 486 patients with acute ischemic stroke. Daily screening for stroke-associated pneumonia, dysphagia and biomarkers was performed. Frequency of stroke-associated pneumonia was 5.2%. Dysphagia and decreased monocytic HLA-DR were independent predictors for stroke-associated pneumonia in multivariable regression analysis. Proportion of pneumonia ranged between 0.9% in the higher monocytic HLA-DR quartile (≥21,876 mAb/cell) and 8.5% in the lower quartile (≤12,369 mAb/cell). In the presence of dysphagia, proportion of pneumonia increased to 5.9% and 18.8%, respectively. Patients without dysphagia and normal monocytic HLA-DR expression had no stroke-associated pneumonia risk. We demonstrate that dysphagia and stroke-induced immunodepression syndrome are independent risk factors for stroke-associated pneumonia. Screening for immunodepression and dysphagia might be useful for identifying patients at high risk for stroke-associated pneumonia.

The effects of key parameters on the transition from SI combustion to HCCI combustion in a two-stroke free piston linear engine

International Nuclear Information System (INIS)

Hung, Nguyen Ba; Lim, Ocktaeck; Iida, Norimasa

2015-01-01

Highlights: • A free piston engine is modeled and simulated by three mathematical models. • The models include dynamic model, linear alternator model and thermodynamic model. • The SI-HCCI transition is successful if the key parameters are adjusted suitably. • Spring stiffness has a strong influence on reducing peak temperature in HCCI mode. • Adjusting spark timing helps the SI-HCCI transition to be more convenient. - Abstract: An investigation was conducted to examine the effects of key parameters such as intake temperature, equivalence ratio, engine load, intake pressure, spark timing and spring stiffness on the transition from SI combustion to HCCI combustion in a two-stroke free piston linear engine. Operation of the free piston engine was simulated based on the combination of three mathematical models including a dynamic model, a linear alternator model and a thermodynamic model. These mathematical models were combined and solved by a program written in Fortran. To validate the mathematical models, the simulation results were compared with experimental data in the SI mode. For the transition from SI combustion to HCCI combustion, the simulation results show that if the equivalence ratio is decreased, the intake temperature and engine load should be increased to get a successful SI-HCCI transition. However, the simulation results also show that the in-cylinder pressure is decreased, while the peak in-cylinder temperature in HCCI mode is increased significantly if the intake temperature is increased so much. Beside the successful SI-HCCI transition, the increase of intake pressure from P in = 1.1 bar to P in = 1.6 bar is one of solutions to reduce peak in-cylinder temperature in HCCI mode. However, the simulation results also indicate that if the intake pressure is increased so much (P in = 1.6 bar), the engine knocking problem is occurred. Adjusting spring stiffness from k = 2.9 N/mm to k = 14.7 N/mm is also considered one of useful solutions for

Caregiver burden and emotional problems in partners of stroke patients at two months and one year post-stroke : Determinants and prediction

NARCIS (Netherlands)

Kruithof, Willeke J.; Post, Marcel W. M.; van Mierlo, Maria L.; van den Bos, Geertrudis A. M.; de Man-van Ginkel, Janneke M.; Visser-Meily, Johanna M. A.

2016-01-01

Objectives: (a) To determine levels of and factors explaining partners' burden, anxiety and depressive symptoms at two months post-stroke, (b) to predict partners' burden, anxiety and depressive symptoms at one year post-stroke based on patient and partner characteristics available at two months

Two-dimensional analysis of two-phase reacting flow in a firing direct-injection diesel engine

Science.gov (United States)

Nguyen, H. Lee

1989-01-01

The flow field, spray penetration, and combustion in two-stroke diesel engines are described. Fuel injection begins at 345 degrees after top dead center (ATDC) and n-dodecane is used as the liquid fuel. Arrhenius kinetics is used to calculate the reaction rate term in the quasi-global combustion model. When the temperature, fuel, and oxygen mass fraction are within suitable flammability limits, combustion begins spontaneously. No spark is necessary to ignite a localized high temperature region. Compression is sufficient to increase the gaseous phase temperature to a point where spontaneous chemical reactions occur. Results are described for a swirl angle of 22.5 degrees.

A validation study using a modified version of Postural Assessment Scale for Stroke Patients: Postural Stroke Study in Gothenburg (POSTGOT

Directory of Open Access Journals (Sweden)

Danielsson Anna

2011-10-01

Full Text Available Abstract Background A modified version of Postural Assessment Scale for Stroke Patients (PASS was created with some changes in the description of the items and clarifications in the manual (e.g. much help was defined as support from 2 persons. The aim of this validation study was to assess intrarater and interrater reliability using this modified version of PASS, at a stroke unit, for patients in the acute phase after their first event of stroke. Methods In the intrarater reliability study 114 patients and in the interrater reliability study 15 patients were examined twice with the test within one to 24 hours in the first week after stroke. Spearman's rank correlation, Kappa coefficients, Percentage Agreement and the newer rank-invariant methods; Relative Position, Relative Concentration and Relative rank Variance were used for the statistical analysis. Results For the intrarater reliability Spearman's rank correlations were 0.88-0.98 and k were 0.70-0.93 for the individual items. Small, statistically significant, differences were found for two items regarding Relative Position and for one item regarding Relative Concentration. There was no Relative rank Variance for any single item. For the interrater reliability, Spearman's rank correlations were 0.77-0.99 for individual items. For some items there was a possible, even if not proved, reliability problem regarding Relative Position and Relative Concentration. There was no Relative rank Variance for the single items, except for a small Relative rank Variance for one item. Conclusions The high intrarater and interrater reliability shown for the modified Postural Assessment Scale for Stroke Patients, the Swedish version of Postural Assessment Scale for Stroke Patients, with traditional and newer statistical analyses, particularly for assessments performed by the same rater, support the use of the Swedish version of Postural Assessment Scale for Stroke Patients, in the acute stage after stroke both

Knowledge of Stroke Risk Factors among Stroke Survivors in Nigeria

OpenAIRE

Grace Vincent-Onabajo; Taritei Moses

2016-01-01

Background. Knowledge of stroke risk factors is expected to reduce the incidence of stroke?whether first-ever or recurrent. This study examined knowledge of stroke risk factors and its determinants among stroke survivors. Methods. A cross-sectional survey of consenting stroke survivors at two physiotherapy facilities in Nigeria was carried out. Sociodemographic and clinical data were obtained and knowledge of stroke risk factors (defined as the ability to mention at least one correct risk fac...

Stroke Burden in Rwanda: A Multicenter Study of Stroke Management and Outcome.

Science.gov (United States)

Nkusi, Agabe Emmy; Muneza, Severien; Nshuti, Steven; Hakizimana, David; Munyemana, Paulin; Nkeshimana, Menelas; Rudakemwa, Emmanuel; Amendezo, Etienne

2017-10-01

Cerebrovascular accidents or stroke constitute the second leading cause of mortality worldwide. Low- and middle-income countries bear most of the stroke burden worldwide. The main objective of this study is to determine the burden of stroke in Rwanda. This was a prospective observational study in 2 parts: 6 months baseline data collection and outcome assessment sessions at 1 year. A total of 96 patients were enrolled in our series. Stroke constituted 2100 per 100,000 population. Of all patients, 55.2% were male and most (60%) were 55 years and older. Of all patients and/or caretakers, 22% were not aware of their previous health status and 53.5% of hypertensive patients were not on treatment by the time of the event. Median presentation delay was 72 hours for patients with ischemic stroke and 24 hours for patients with hemorrhagic stroke. Most patients had hemorrhagic stroke (65% vs. 35%), and more patients with hemorrhagic stroke presented with loss of consciousness (80% vs. 51%). Many patients (62% ischemic group and 44% hemorrhagic group) presented with severe stroke scores, and this was associated with worst outcome (P = 0.004). At 1 year follow-up, 24.7% had no or mild disability, 14.3% were significantly disabled, and 61% had died. Our results show that stroke is a significant public health concern in Rwanda. Risk factor awareness and control are still low and case fatality of stroke is significantly high. The significant delay in presentation to care and presentation with severe stroke are major contributors for the high mortality and severe disability rates. Copyright © 2017 Elsevier Inc. All rights reserved.

A quasi-experimental study on a community-based stroke prevention programme for clients with minor stroke.

Science.gov (United States)

Sit, Janet W H; Yip, Vera Y B; Ko, Stanley K K; Gun, Amy P C; Lee, Judy S H

2007-02-01

The aim of this study was to determine the effectiveness of a community-based stroke prevention programme in (1) improving knowledge about stroke; (2) improving self-health-monitoring practice; (3) maintaining behavioural changes when adopting a healthy lifestyle for stroke prevention. People with minor stroke (or transient ischaemic attack) tend to under-estimate the long-term impact of this on their health. The challenge for nurses is to prevent subsequent strokes by finding ways to promote and sustain appropriate behaviours. Educational intervention is of paramount importance in equipping those at risk with relevant knowledge and self-care strategies for secondary stroke prevention. This study adopted a quasi-experimental design. One hundred and ninety subjects were recruited, of whom 147 (77 in the intervention group and 70 in the control group) completed the study. Data were obtained at three time points: baseline (T0); one week after (T1) and three months after (T2) the intervention. The intervention programme consisted of eight weekly two-hour sessions, with the aims of improving the participants' awareness of their own health signals and of actively involving them in self-care management of their own health for secondary stroke prevention. Significant positive changes were found among participants of the intervention group in the knowledge on stroke warning signs (P lifestyle modification of dietary habits (reduction in salted food intake, P = 0.004). No significant improvement was found in walking exercise participation in the intervention group, yet a significant decrease was detected among the control group. This study found a three-month-sustained effect of positive changes in knowledge and skill from participants who undertook a nurse-led community-based stroke prevention programme. Effective educational intervention by professional nurses helped clients integrate their learned knowledge into their real-life practice. This empowering, that is, the

Ethnic differences in ischemic stroke subtypes in young-onset stroke: the Stroke Prevention in Young Adults Study.

Science.gov (United States)

Trivedi, Megh M; Ryan, Kathleen A; Cole, John W

2015-10-29

Prior studies indicate that young African-Americans (AA) have a greater frequency of ischemic stroke than similarly aged European-Americans (EA). We hypothesized that differences in stroke subtype frequency mediated through sex and differing risk factor profiles may play a role in ethnicity-specific stroke. Utilizing our biracial young-onset stroke population, we explored these relationships. Fifty nine hospitals in the Baltimore-Washington area participated in a population-based study of young-onset stroke in men (218-AA, 291-EA) and women (219-AA, 222-EA) aged 16-49. Data on age, sex, ethnicity and stroke risk factors (hypertension (HTN) and smoking) were gathered through standardized interview. A pair of vascular neurologists adjudicated each case to determine TOAST subtype. Logistic regression analyses evaluating for differences in stroke risk factors by TOAST subtype were performed. Analyses controlling for age and sex demonstrated that AA were more likely to have a lacunar stroke than EA (OR = 1.61; 95% CI = 1.12-2.32; p = 0.011) when utilizing the other TOAST subtypes as the reference group. This effect was mediated by HTN, which increases the risk of lacunar stroke (OR = 2.03; 95% CI = 1.38-2.98; p = 0.0003) and large artery stroke (OR = 1.70; 95% CI = 1.01-2.88; p = 0.048) when controlling for sex, ethnicity, and age. Cases below age 40 were more likely to have a cardioembolic stroke than those above age 40 (OR = 1.62; 95% CI = 1.15-2.27; p = 0.006), controlling for sex and ethnicity. Lastly, current smokers were more likely to have a large artery stroke than non-smokers (OR = 1.79; 95% CI = 1.08-2.98; p = 0.024). Our population-based data demonstrate ethnic differences in ischemic stroke subtypes. These findings may help clarify mechanisms of stroke in young adults which may in part be driven by ethnic-specific differences in early-onset traditional risk factors, thereby indicating differing emphasis on workup and prevention.

A report of heat stroke in two Nigerian siblings

African Journals Online (AJOL)

2014-05-31

May 31, 2014 ... Two Nigerian siblings aged ... Case Report. Two male siblings, aged 3 (Case 1) and 5‑year‑old (Case 2) ... stroke with the resultant neurological and multi organ dysfunction,[11] ... urine color cleared within 24 h of admission.

Aerodynamic efficiency of flapping flight: analysis of a two-stroke model.

Science.gov (United States)

Wang, Z Jane

2008-01-01

To seek the simplest efficient flapping wing motions and understand their relation to steady flight, a two-stroke model in the quasi-steady limit was analyzed. It was found that a family of two-stroke flapping motions have aerodynamic efficiency close to, but slightly lower than, the optimal steady flight. These two-stroke motions share two common features: the downstroke is a gliding motion and the upstroke has an angle of attack close to the optimal of the steady flight of the same wing. With the reduced number of parameters, the aerodynamic cost function in the parameter space can be visualized. This was examined for wings of different lift and drag characteristics at Reynolds numbers between 10(2) and 10(6). The iso-surfaces of the cost function have a tube-like structure, implying that the solution is insensitive to a specific direction in the parameter space. Related questions in insect flight that motivated this work are discussed.

Supratentorial arterial ischemic stroke following cerebellar tumor resection in two children.

Science.gov (United States)

Catsman-Berrevoets, Coriene E; van Breemen, Melanie; van Veelen, Marie Lise; Appel, Inge M; Lequin, Maarten H

2005-01-01

We describe two children who developed ischemic strokes in the territory of the middle cerebral artery, one 7 days and one 11 days after resection of a cerebellar tumor. In the first child, another infarction occurred in the territory of the contralateral middle cerebral artery 5 days after the first stroke. No specific cause or underlying risk factor other than the surgical procedure was found. The subacute clinical course at stroke onset resembled that of the 'posterior fossa syndrome', suggesting a common underlying mechanism.

Exhaust temperature analysis of four stroke diesel engine by using MWCNT/Water nanofluids as coolant

Science.gov (United States)

Muruganandam, M.; Mukesh Kumar, P. C.

2017-10-01

There has been a continuous improvement in designing of cooling system and in quality of internal combustion engine coolants. The liquid engine coolant used in early days faced many difficulties such as low boiling, freezing points and inherently poor thermal conductivity. Moreover, the conventional coolants have reached their limitations of heat dissipating capacity. New heat transfer fluids have been developed and named as nanofluids to try to replace traditional coolants. Moreover, many works are going on the application of nanofluids to avail the benefits of them. In this experimental investigation, 0.1, 0.3 and 0.5% volume concentrations of multi walled carbon nanotube (MWCNT)/water nanofluids have been prepared by two step method with surfactant and is used as a coolant in four stroke single cylinder diesel engine to assess the exhaust temperature of the engine. The nanofluid prepared is characterized with scanning electron microscope (SEM) to confirm uniform dispersion and stability of nanotube with zeta potential analyzer. Experimental tests are performed by various mass flow rate such as 270 300 330 LPH (litre per hour) of coolant nanofluids and by changing the load in the range of 0 to 2000 W and by keeping the engine speed constant. It is found that the exhaust temperature decreases by 10-20% when compared to water as coolant at the same condition.

Study of the Injection Control Strategies of a Compression Ignition Free Piston Engine Linear Generator in a One-Stroke Starting Process

Directory of Open Access Journals (Sweden)

Huihua Feng

2016-06-01

Full Text Available For a compression ignition (CI free piston engine linear generator (FPLG, injection timing is one of the most important parameters that affect its performance, especially for the one-stroke starting operation mode. In this paper, two injection control strategies are proposed using piston position and velocity signals. It was found experimentally that the injection timing’s influence on the compression ratio, the peak in-cylinder gas pressure and the indicated work (IW is different from that of traditional reciprocating CI engines. The maximum IW of the ignition starting cylinder, say left cylinder (LC and the right cylinder (RC are 132.7 J and 138.1 J, respectively. The thermal-dynamic model for simulating the working processes of the FPLG are built and verified by experimental results. The numerical simulation results show that the running instability and imbalance between LC and RC are the obvious characters when adopting the injection strategy of the velocity feedback. These could be solved by setting different triggering velocity thresholds for the two cylinders. The IW output from the FPLG under this strategy is higher than that of adopting the position feedback strategy, and the maximum IW of the RC could reach 162.3 J. Under this strategy, the prototype is able to achieve better starting conditions and could operate continuously for dozens of cycles.

Hemorrhagic stroke in the Stroke Prevention by Aggressive Reduction in Cholesterol Levels study

DEFF Research Database (Denmark)

Goldstein, L.B.; Amarenco, P.; Szarek, M.

2008-01-01

BACKGROUND: In the Stroke Prevention by Aggressive Reduction in Cholesterol Levels (SPARCL) study, atorvastatin 80 mg/day reduced the risk of stroke in patients with recent stroke or TIA. Post hoc analysis found this overall benefit included an increase in the numbers of treated patients having......: Of 4,731 patients, 67% had ischemic strokes, 31% TIAs, and 2% hemorrhagic strokes as entry events. In addition to atorvastatin treatment (HR 1.68, 95% CI 1.09 to 2.59, p = 0.02), Cox multivariable regression including baseline variables significant in univariable analyses showed that hemorrhagic stroke...... and treatment. Multivariable analyses also found that having Stage 2 (JNC-7) hypertension at the last study visit before a hemorrhagic stroke increased risk (HR 6.19, 95% CI 1.47 to 26.11, p = 0.01), but there was no effect of most recent LDL-cholesterol level in those treated with atorvastatin. CONCLUSIONS...

Bobath or motor relearning programme? A comparison of two different approaches of physiotherapy in stroke rehabilitation: a randomized controlled study.

Science.gov (United States)

Langhammer, B; Stanghelle, J K

2000-08-01

To examine whether two different physiotherapy regimes caused any differences in outcome in rehabilitation after acute stroke. A double-blind study of patients with acute first-ever stroke. Sixty-one patients were consecutively included, block randomized into two groups, and stratified according to gender and hemiplegic site. Group 1 (33 patients) and group 2 (28 patients) had physiotherapy according to Motor Relearning Programme (MRP) and Bobath, respectively. The supplemental treatment did not differ in the two groups. The Motor Assessment Scale (MAS), the Sødring Motor Evaluation Scale (SMES), the Barthel ADL Index and the Nottingham Health Profile (NHP) were used. The following parameters were also registered: length of stay in the hospital, use of assistive devices for mobility, and the patient's accommodation after discharge from the hospital. Patients treated according to MRP stayed fewer days in hospital than those treated according to Bobath (mean 21 days versus 34 days, p = 0.008). Both groups improved in MAS and SMES, but the improvement in motor function was significantly better in the MRP group. The two groups improved in Barthel ADL Index without significant differences between the groups. However, women treated by MRP improved more in ADL than women treated by Bobath. There were no differences between the groups in the life quality test (NHP), use of assistive devices or accommodation after discharge from the hospital. The present study indicates that physiotherapy treatment using the MRP is preferable to that using the Bobath programme in the acute rehabilitation of stroke patients.

A prospective cohort study of stroke characteristics, care, and mortality in a hospital stroke registry in Vietnam

Directory of Open Access Journals (Sweden)

Tirschwell David L

2012-12-01

Full Text Available Abstract Background As low and middle-income countries such as Vietnam experience the health transition from infectious to chronic diseases, the morbidity and mortality from stroke will rise. In line with the recommendation of the Institute of Medicine’s report on “Promoting Cardiovascular Health in the Developing World” to “improve local data”, we sought to investigate patient characteristics and clinical predictors of mortality among stroke inpatients at Da Nang Hospital in Vietnam. Methods A stroke registry was developed and implemented at Da Nang Hospital utilizing the World Health Organization’s Stroke STEPS instrument for data collection. Results 754 patients were hospitalized for stroke from March 2010 through February 2011 and admitted to either the intensive care unit or cardiology ward. Mean age was 65 years, and 39% were female. Nearly 50% of strokes were hemorrhagic. At 28-day follow-up, 51.0% of patients with hemorrhagic stroke died whereas 20.3% of patients with ischemic stroke died. A number of factors were independently associated with 28-day mortality; the two strongest independent predictors were depressed level of consciousness on presentation and hemorrhagic stroke type. While virtually all patients completed a CT during the admission, evidence-based processes of care such as anti-thrombotic therapy and carotid ultrasound for ischemic stroke patients were underutilized. Conclusions This cohort study highlights the high mortality due in part to the large proportion of hemorrhagic strokes in Vietnam. Lack of hypertension awareness and standards of care exacerbated clinical outcomes. Numerous opportunities for simple, inexpensive interventions to improve outcomes or reduce recurrent stroke have been identified.

Chemical characterization of emissions from modern two-stroke mopeds complying with legislative regulation in Europe (EURO-2).

Science.gov (United States)

Adam, T; Farfaletti, A; Montero, L; Martini, G; Manfredi, U; Larsen, B; Santi, G De; Krasenbrink, A; Astorga, C

2010-01-01

In view of a new amendment to the European legislative regulation on emissions from two-stroke mopeds a study was carried out to comprehensively characterize exhaust gases of mopeds complying current EURO-2 emission standards. Three mopeds with different engine types (carburetor, direct injection, and electronic carburetion system ECS) where investigated by applying two different driving cycles, the legislative cycle ECE47 and the worldwide motorcycle test cycle WMTC. Thereby, particulate matter (PM), regulated compounds, carbonyls, volatile hydrocarbons (VOC), and particle-associated polyaromatic hydrocarbons (PAH) were analyzed and ozone formation potentials (OFP) as well as toxicity equivalents (TEQ) determined. The ECE47 emission factors for almost all species and moped types were much higher in the nonregulated, prior cold phase than in the hot phase, which is considered for legislation. Great differences for the mopeds could be observed for NO(x), VOC, and PM, whereas discrepancies between the driving cycles ECE47 and WMTC were smaller. In addition, a positive influence on exhaust composition caused by technical modifications of the ECS engine was determined. Results indicate that regulation of total hydrocarbons (THC) alone might not be sufficient to regulate PM, especially for direct injection engines. Moreover, recommendations for a revised future test protocol are demonstrated and discussed, whereby the cold phase and the hot phase are taken into account.

Thermal balance of a four stroke SI engine operating on hydrogen as a supplementary fuel

International Nuclear Information System (INIS)

Yueksel, F.; Ceviz, M.A.

2003-01-01

This paper investigates the effects of adding constant quantity hydrogen to gasoline-air mixture on SI engine thermal balance and performance. A four stroke, four-cylinder SI engine was used for conducting this study. Thermal balance tests were conducted for engine thermal efficiency, heat loss through the exhaust gases, heat loss to the cooling water and unaccounted losses (i.e. heat lost by lubricating oil, radiation), while performance tests were in respect to the brake power, specific fuel consumption and air ratio. Hydrogen supplementations were used with three different and fixed mass flow rates; 0.129, 0.168 and 0.208 kg h -1 at near three-fourth throttle opening position and variable engine speed ranging from 1000 to 4500 rpm. The results showed that supplementation of hydrogen to gasoline decreases the heat loss to cooling water and unaccounted losses, and the heat loss through the exhaust gas is nearly the same with pure gasoline experiments. Additionally, specific fuel consumption decreases, while the engine thermal efficiency and the air ratio increase. Engine performance parameters such as thermal efficiency and specific fuel consumption improved the level of the ratio of hydrogen mass flow rate to that of gasoline up to 5%

Short- and long-term prognosis for very old stroke patients. The Copenhagen Stroke Study

DEFF Research Database (Denmark)

Kammersgaard, Lars Peter; Jørgensen, H S; Reith, J

2004-01-01

BACKGROUND AND PURPOSE: The very old are expected to become a growing part of the stroke population in the industrialised part of the world. The aims of this study were to evaluate clinical characteristics of patients aged 85 years or more at stroke onset and to investigate very old age as an ind...... and rehabilitation after stroke.......BACKGROUND AND PURPOSE: The very old are expected to become a growing part of the stroke population in the industrialised part of the world. The aims of this study were to evaluate clinical characteristics of patients aged 85 years or more at stroke onset and to investigate very old age...... as an independent predictor of short- and long-term outcome. METHODS: In the community-based Copenhagen Stroke Study we recorded admission clinical characteristics in 1197 consecutive stroke patients. Patients were stratified according to age groups on admission. Follow-up was performed at a mean of 7 years after...

An analytical and experimental study of performance on jatropha biodiesel engine

Directory of Open Access Journals (Sweden)

Ganapathy Thirunavukkarasu

2009-01-01

Full Text Available Biodiesel plays a major role as one of the alternative fuel options in direct injection diesel engines for more than a decade. Though many feed stocks are employed for making biodiesel worldwide, biodiesel derived from domestically available non-edible feed stocks such as Jatropha curcas L. is the most promising alternative engine fuel option especially in developing countries. Since experimental analysis of the engine is pricey as well as more time consuming and laborious, a theoretical thermodynamic model is necessary to analyze the performance characteristics of jatropha biodiesel fueled diesel engine. There were many experimental studies of jatropha biodiesel fueled diesel engine reported in the literature, yet theoretical study of this biodiesel run diesel engine is scarce. This work presents a theoretical thermodynamic study of single cylinder four stroke direct injection diesel engine fueled with biodiesel derived from jatropha oil. The two zone thermodynamic model developed in the present study computes the in-cylinder pressure and temperature histories in addition to various performance parameters. The results of the model are validated with experimental values for a reasonable agreement. The variation of cylinder pressure with crank angle for various models are also compared and presented. The effects of injection timing, relative air fuel ratio and compression ratio on the engine performance characteristics for diesel and jatropha biodiesel fuels are then investigated and presented in the paper.

Analysis of Effect of Inlet Swirl In Four Stroke Single Cylinder Diesel Engine With Different Inlet Valve Geometries Using CFD

Science.gov (United States)

Gobinath, R.; Mathiselvan, G.; Kumarasubramanian, R.

2017-05-01

Flow patterns are essential to ensure that the engine can produce high performance with the presence of swirl and tumble effect inside the engine cylinder. This paper provides the simulation of air is simulated in the software to predict the flow pattern. The flow pattern is simulated by using the steady state pressure based solver. The domain used for the simulations predicated on the particular engine parameters. Mistreatment the CFD problem solver ANSYS FLUENT, the CFD simulation is earned for four totally different geometries of the valve. The geometries consist of Horizontal, Vertical, curve and arc springs. In this simulation, only the intake strokes are simulated. From this results show that the velocity of the air flow is high during the sweeps the intake stroke takes place. This situation is produced more swirls and tumble effect during the compression, hence enhancing the combustion rate in a whole region of the clearance volume of the engine cylinder. This will initiate to the production of tumble and swirl in the engine cylinder.

The Charging Process in a High-speed, Single-cylinder, Four-stroke Engine

Science.gov (United States)

Reynolds, Blake; Schecter, Harry; Taylor, E S

1939-01-01

Experimental measurements and theoretical calculations were made on an aircraft-type, single cylinder engine, in order to determine the physical nature of the inlet process, especially at high piston speeds. The engine was run at speeds from 1,500 to 2,600 r.p.m. (mean piston speeds of 1,370 to 2,380 feet per minute). Measurements were made of the cylinder pressure during the inlet stroke and of the power output and volumetric efficiency. Measurements were also made, with the engine not running, to determine the resistance and mass of air in the inlet valve port at various crank angles. Results of analysis indicate that mass has an appreciable effect, but friction plays the major part in restricting flow. The observed fact that the volumetric efficiency is considerably less than 100 percent is attributed to thermal effects. An estimate was made of the magnitude of these effects in the present case, and their general nature is discussed.

Free-piston engine

Science.gov (United States)

Van Blarigan, Peter

2001-01-01

A combustion system which can utilize high compression ratios, short burn durations, and homogeneous fuel/air mixtures in conjunction with low equivalence ratios. In particular, a free-piston, two-stroke autoignition internal combustion engine including an electrical generator having a linear alternator with a double-ended free piston that oscillates inside a closed cylinder is provided. Fuel and air are introduced in a two-stroke cycle fashion on each end, where the cylinder charge is compressed to the point of autoignition without spark plugs. The piston is driven in an oscillating motion as combustion occurs successively on each end. This leads to rapid combustion at almost constant volume for any fuel/air equivalence ratio mixture at very high compression ratios. The engine is characterized by high thermal efficiency and low NO.sub.x emissions. The engine is particularly suited for generating electrical current in a hybrid automobile.

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

Science.gov (United States)

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.

Systemic risk score evaluation in ischemic stroke patients (SCALA): a prospective cross sectional study in 85 German stroke units.

Science.gov (United States)

Weimar, Christian; Goertler, Michael; Röther, Joachim; Ringelstein, E Bernd; Darius, Harald; Nabavi, Darius Günther; Kim, In-Ha; Theobald, Karlheinz; Diener, Han-Christoph

2007-11-01

Stratification of patients with transient ischemic attack (TIA) or ischemic stroke (IS) by risk of recurrent stroke can contribute to optimized secondary prevention. We therefore aimed to assess cardiovascular risk factor profiles of consecutive patients hospitalized with TIA/IS to stratify the risk of recurrent stroke according to the Essen Stroke Risk Score (ESRS) and of future cardiovascular events according to the ankle brachial index (ABI) as a marker of generalized atherosclerosis In this cross-sectional observational study, 85 neurological stroke units throughout Germany documented cardiovascular risk factor profiles of 10 consecutive TIA/IS patients on standardized questionnaires. Screening for PAD was done with Doppler ultrasonography to calculate the ABI. A total of 852 patients (57% men) with a mean age of 67+/-12.4 years were included of whom 82.9 % had IS. The median National Institutes of Health stroke sum score was 4 (TIA: 1). Arterial hypertension was reported in 71%, diabetes mellitus in 26%, clinical PAD in 10%, and an ABI or = 3 was observed in 58%, which in two previous retrospective analyses corresponded to a recurrent stroke risk of > or = 4%/year. The correlation between the ESRS and the ABI was low (r = 0.21). A high proportion of patients had asymptomatic atherosclerotic disease and a considerable risk of recurrent stroke according to the ABI and ESRS category. The prognostic accuracy as well as the potential benefit of various risk stratification scores in secondary stroke prevention require validation in a larger prospective study.

Risk Factors for Stroke-associated Pneumonia: A Prospective Cohort Study

Directory of Open Access Journals (Sweden)

Alexis Suárez Quesada

2015-12-01

Full Text Available Background: stroke-associated pneumonia prolongs hospital stay and is an important risk factor for morbidity and mortality. Objective: to determine risk factors for stroke-associated pneumonia. Methods: a prospective single-cohort study was conducted involving 390 patients aged 16-93 years who met clinical and neuroimaging criteria for acute stroke treated at the Carlos Manuel de Céspedes Hospital from January 2012 through March 2015. Univariate comparison of qualitative variables was performed by using the Kaplan-Meier method. The Cox regression model was applied for multivariate analysis of risk factors for pneumonia. The area under the ROC curve was used to determine the discriminatory power of the model. Results: two hundred thirteen patients (54.6 % with ischemic stroke and 177 (45.4 % with hemorrhagic stroke were studied. Cases of nosocomial pneumonia after acute stroke accounted for 25.4 %. Subjects who developed pneumonia had lower scores on the Glasgow scale and higher scores on the modified Rankin scale. The following risk factors were identified using the Cox regression model: Glasgow coma score (Exp (B: 0.687; 95 % CI 0.630 to 0.750 and stroke subtype (Exp (B: 1.723; 95 % CI 1.137 to 2.610. The area under the ROC curve was 0.88. Conclusions: the risk factors for the development of nosocomial pneumonia after acute stroke found were the level of consciousness and suffering a hemorrhagic stroke. Other influencing variables are chronic obstructive pulmonary disease and heart disease as a comorbid condition.

Large Eddy Simulations of Two-phase Turbulent Reactive Flows in IC Engines

Science.gov (United States)

Banaeizadeh, Araz; Schock, Harold; Jaberi, Farhad

2008-11-01

The two-phase filtered mass density function (FMDF) subgrid-scale (SGS) model is used for large-eddy simulation (LES) of turbulent spray combustion in internal combustion (IC) engines. The LES/FMDF is implemented via an efficient, hybrid numerical method. In this method, the filtered compressible Navier-Stokes equations in curvilinear coordinate systems are solved with a generalized, high-order, multi-block, compact differencing scheme. The spray and the FMDF are implemented with Lagrangian methods. The reliability and the consistency of the numerical methods are established for different IC engines and the complex interactions among mean and turbulent velocity fields, fuel droplets and combustion are shown to be well captured with the LES/FMDF. In both spark-ignition/direct-injection and diesel engines, the droplet size and velocity distributions are found to be modified by the unsteady, vortical motions generated by the incoming air during the intake stroke. In turn, the droplets are found to change the in-cylinder flow structure. In the spark-ignition engine, flame propagation is similar to the experiment. In the diesel engine, the maximum evaporated fuel concentration is near the cylinder wall where the flame starts, which is again consistent with the experiment.

The Siblings With Ischemic Stroke Study (SWISS Protocol

Directory of Open Access Journals (Sweden)

Hardy John

2002-02-01

Full Text Available Abstract Background Family history and twins studies suggest an inherited component to ischemic stroke risk. Candidate gene association studies have been performed but have limited capacity to identify novel risk factor genes. The Siblings With Ischemic Stroke Study (SWISS aims to conduct a genome-wide scan in sibling pairs concordant or discordant for ischemic stroke to identify novel genetic risk factors through linkage analysis. Methods Screening at multiple clinical centers identifies patients (probands with radiographically confirmed ischemic stroke and a family history of at least 1 living full sibling with stroke. After giving informed consent, without violating privacy among other family members, the proband invites siblings concordant and discordant for stroke to participate. Siblings then contact the study coordinating center. The diagnosis of ischemic stroke in potentially concordant siblings is confirmed by systematic centralized review of medical records. The stroke-free status of potentially discordant siblings is confirmed by validated structured telephone interview. Blood samples for DNA analysis are taken from concordant sibling pairs and, if applicable, from 1 discordant sibling. Epstein-Barr virus-transformed lymphoblastoid cell lines are created, and a scan of the human genome is planned. Discussion Conducting adequately powered genomics studies of stroke in humans is challenging because of the heterogeneity of the stroke phenotype and the difficulty of obtaining DNA samples from clinically well-characterized members of a cohort of stroke pedigrees. The multicentered design of this study is intended to efficiently assemble a cohort of ischemic stroke pedigrees without invoking community consent or using cold-calling of pedigree members.

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

Science.gov (United States)

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

A CLINICAL STUDY OF STROKE IN YOUNG

Directory of Open Access Journals (Sweden)

Kumbha Thulasi Ram

2015-02-01

Full Text Available NTRIDUCTION : Stroke is one of the important causes of morbidity and mortality all over the world. Incidence of stroke steadily increases with age. Experts are concerned of the emerging stroke epidemic in India. Stroke affecting the young has potentially devastating consequence son the individual and his family. Certain risk factors are unique to the young. I t needs more studies for identification and modification of risk factors. The study aims to evaluate clinical features, risk factors, etiology and mortality of stroke in young patients. METHODS : 74 young patients satisfying the inclusion criteria were included in this study. A detailed history was taken from young stroke patients, systemic examination and required investigations were done. Data was collected in standardized proforma and analysed. RESULTS: Stroke in young accounts for 7.95% of stroke cases of all age groups. The mean age of the patients was 34.66 ± 7.48 years. Among 74 patients, 47(63.51% were male and 27(36.49% were female. Seizures, decreased consciousness, speech involvement and motor deficit were observed in 33.78%, 44.59%, 22.97% and 100% of cases respectively. 82.43% patients had ischemic and 17.57% patients had hemorrhagic stroke. Among ischemic stroke, large artery atherosclerosis was 16.21%, tuberculous meningoencephalitis with vasculitis was 16.21%, lacunar stroke was 10.81%, CVT was 10.81% and cardio embolic stroke was 6.76%. Smoking (59.45%, alcoholism (58.10%, hypertension (43.24%, coronary artery disease (8.10%, diabetes mellitus (10.81%, elevated total cholesterol (25.67%, elevated low density lipo proteins (22.97%, elevated triglycerides (27.02% and low HDL (22.97% were important risk factors. Carotid doppler was abnormal in 9.45% of patients. 6.76% patients had mitral stenosis in echocardiogram. Low protein C and protein S were found in 1.35% of patients. Eight (10.81% patients died during the hospital stay. INTERPRETATION AND CONCLUSIONS: The major risk

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

Science.gov (United States)

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...

Resonance vibrations in intake and exhaust pipes of in-line engines III : the inlet process of a four-stroke-cycle engine

Science.gov (United States)

Lutz, O

1940-01-01

Using a previously developed method, the boundary process of four-stroke-cycle engines are set up. The results deviate considerably from those obtained under the assumption that the velocity fluctuation is proportional to the cylinder piston motion. The deviation is less at the position of resonance frequencies. By the method developed, the effect of the resonance vibrations on the volumetric efficiency can be demonstrated.

Post-stroke depression among stroke survivors attending two ...

African Journals Online (AJOL)

African Health Sci

The Patient Health Questionnaire-9 was used to assess for depression ... Stroke is a common neurological problem and one of ... students. Nsambya hospital is a private not for profit, church aided institution, while Mulago is a government.

Simultaneous Study of Intake and In-Cylinder IC Engine Flow Fields to Provide an Insight into Intake Induced Cyclic Variations

International Nuclear Information System (INIS)

Justham, T; Jarvis, S; Clarke, A; Garner, C P; Hargrave, G K; Halliwell, N A

2006-01-01

Simultaneous intake and in-cylinder digital particle image velocimetry (DPIV) experimental data is presented for a motored spark ignition (SI) optical internal combustion (IC) engine. Two individual DPIV systems were employed to study the inter-relationship between the intake and in-cylinder flow fields at an engine speed of 1500 rpm. Results for the intake runner velocity field at the time of maximum intake valve lift are compared to incylinder velocity fields later in the same engine cycle. Relationships between flow structures within the runner and cylinder were seen to be strong during the intake stroke but less significant during compression. Cyclic variations within the intake runner were seen to affect the large scale bulk flow motion. The subsequent decay of the large scale motions into smaller scale turbulent structures during the compression stroke appear to reduce the relationship with the intake flow variations

Simultaneous Study of Intake and In-Cylinder IC Engine Flow Fields to Provide an Insight into Intake Induced Cyclic Variations

Energy Technology Data Exchange (ETDEWEB)

Justham, T; Jarvis, S; Clarke, A; Garner, C P; Hargrave, G K; Halliwell, N A [Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU (United Kingdom)

2006-07-15

Simultaneous intake and in-cylinder digital particle image velocimetry (DPIV) experimental data is presented for a motored spark ignition (SI) optical internal combustion (IC) engine. Two individual DPIV systems were employed to study the inter-relationship between the intake and in-cylinder flow fields at an engine speed of 1500 rpm. Results for the intake runner velocity field at the time of maximum intake valve lift are compared to incylinder velocity fields later in the same engine cycle. Relationships between flow structures within the runner and cylinder were seen to be strong during the intake stroke but less significant during compression. Cyclic variations within the intake runner were seen to affect the large scale bulk flow motion. The subsequent decay of the large scale motions into smaller scale turbulent structures during the compression stroke appear to reduce the relationship with the intake flow variations.

Simultaneous Study of Intake and In-Cylinder IC Engine Flow Fields to Provide an Insight into Intake Induced Cyclic Variations

Science.gov (United States)

Justham, T.; Jarvis, S.; Clarke, A.; Garner, C. P.; Hargrave, G. K.; Halliwell, N. A.

2006-07-01

Simultaneous intake and in-cylinder digital particle image velocimetry (DPIV) experimental data is presented for a motored spark ignition (SI) optical internal combustion (IC) engine. Two individual DPIV systems were employed to study the inter-relationship between the intake and in-cylinder flow fields at an engine speed of 1500 rpm. Results for the intake runner velocity field at the time of maximum intake valve lift are compared to incylinder velocity fields later in the same engine cycle. Relationships between flow structures within the runner and cylinder were seen to be strong during the intake stroke but less significant during compression. Cyclic variations within the intake runner were seen to affect the large scale bulk flow motion. The subsequent decay of the large scale motions into smaller scale turbulent structures during the compression stroke appear to reduce the relationship with the intake flow variations.

A new hybrid pneumatic combustion engine to improve fuel consumption of wind–Diesel power system for non-interconnected areas

International Nuclear Information System (INIS)

Basbous, Tammam; Younes, Rafic; Ilinca, Adrian; Perron, Jean

2012-01-01

Highlights: ► We model thermodynamic ideal cycle of a new hybrid pneumaticcombustion engine. ► We optimize commands of all modes and calculate maps of fuel and air consumption. ► We evaluate fuel economy for Wind–Diesel system function of tank volume and wind penetration. ► We find up to 10% of fuel economy i.e. 80 t/year with 100% wind penetration. ► Fuel economy increases with wind penetration and with volume but has asymptotic value. -- Abstract: This paper presents an evaluation of an optimized Hybrid Pneumatic-Combustion Engine (HPCE) concept that permits reducing fuel consumption for electricity production in non-interconnected remote areas, originally equipped with hybrid Wind–Diesel System (WDS). Up to now, most of the studies on the pneumatic hybridization of Internal Combustion Engines (ICE) have dealt with two-stroke pure pneumatic mode. The few studies that have dealt with hybrid pneumatic-combustion four-stroke mode require adding a supplementary valve to charge compressed air in the combustion chamber. This modification means that a new cylinder head should be fabricated. Moreover, those studies focus on spark ignition engines and are not yet validated for Diesel engines. Present HPCE is capable of making a Diesel engine operate under two-stroke pneumatic motor mode, two-stroke pneumatic pump mode and four-stroke hybrid mode, without needing an additional valve in the combustion chamber. This fact constitutes this study’s strength and innovation. The evaluation of the concept is based on ideal thermodynamic cycle modeling. The optimized valve actuation timings for all modes lead to generic maps that are independent of the engine size. The fuel economy is calculated for a known site during a whole year, function of the air storage volume and the wind power penetration rate.

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

Science.gov (United States)

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

Methodology of a population-based stroke and TIA incidence and outcomes study: the Auckland Regional Community Stroke Study (ARCOS IV) 2011-2012.

Science.gov (United States)

Krishnamurthi, Rita; Jones, Amy; Barber, P Alan; Barker-Collo, Suzanne; McPherson, Kathryn; Bennett, Derrick; Rush, Elaine; Suh, Flora; Starkey, Nicola; Theadom, Alice; Parag, Varsha; Rathnasabapathy, Yogini; Feigin, Valery L

2014-01-01

Stroke is a leading cause of death and disability worldwide. Stroke burden is immense as it leads to premature deaths, leaves survivors with ongoing disabilities, and has a major financial impact on the individual, their families, and the community. Reliable, high-quality evidence is needed on stroke risk factors, incidence, and outcomes to provide information on how best to reduce this burden. Population-based studies are regarded as the 'gold-standard' of measuring disease burden but are not common due to the logistical and financial challenges they present. The Auckland Regional Community Stroke Studies are among a few in the world that have been carried out at a population level and at regular intervals. The aim of the fourth Auckland Regional Community Stroke Studies IV is to examine the current measures of stroke incidence, prevalence, and outcomes as well the trends over four decades. This article describes the methodology of the Auckland Regional Community Stroke Studies IV with stroke and transient ischemic attacks cases registered over a 12-month period from March 1, 2011 to February 29, 2012. The methodology described may be used as a guide in order to design similar population-based stroke incidence and outcome studies in other countries and populations, thus facilitating the collection of most consistent and accurate stroke epidemiological data. © 2013 The Authors. International Journal of Stroke © 2013 World Stroke Organization.

Help seeking behavior and onset-to-alarm time in patients with acute stroke: sub-study of the preventive antibiotics in stroke study.

Science.gov (United States)

Zock, E; Kerkhoff, H; Kleyweg, R P; van Bavel-Ta, T B V; Scott, S; Kruyt, N D; Nederkoorn, P J; van de Beek, D

2016-11-25

Patients with acute stroke often do not seek immediate medical help, which is assumed to be driven by lack of knowledge of stroke symptoms. We explored the process of help seeking behavior in patients with acute stroke, evaluating knowledge about stroke symptoms, socio-demographic and clinical characteristics, and onset-to-alarm time (OAT). In a sub-study of the Preventive Antibiotics in Stroke Study (PASS), 161 acute stroke patients were prospectively included in 3 Dutch hospitals. A semi-structured questionnaire was used to assess knowledge, recognition and interpretation of stroke symptoms. With in-depth interviews, response actions and reasons were explored. OAT was recorded and associations with socio-demographic, clinical parameters were assessed. Knowledge about stroke symptoms does not always result in correct recognition of own stroke symptoms, neither into correct interpretation of the situation and subsequent action. In our study population of 161 patients with acute stroke, median OAT was 30 min (interquartile range [IQR] 10-150 min). Recognition of one-sided weakness and/or sensory loss (p = 0.046) and adequate interpretation of the stroke situation (p = 0.003), stroke at daytime (p = 0.002), severe stroke (p = 0.003), calling the emergency telephone number (p = 0.004), and transport by ambulance (p = 0.040) were associated with shorter OAT. Help seeking behavior after acute stroke is a complex process. A shorter OAT after stroke is associated with correct recognition of one-sided weakness and/or sensory loss, adequate interpretation of the stroke situation by the patient and stroke characteristics and logistics of stroke care, but not by knowledge of stroke symptoms.

Factor V leiden and ischemic stroke risk: the Genetics of Early Onset Stroke (GEOS) study.

Science.gov (United States)

Hamedani, Ali G; Cole, John W; Cheng, Yuching; Sparks, Mary J; O'Connell, Jeffrey R; Stine, Oscar C; Wozniak, Marcella A; Stern, Barney J; Mitchell, Braxton D; Kittner, Steven J

2013-05-01

Factor V Leiden (FVL) has been associated with ischemic stroke in children but not in adults. Although the FVL mutation is associated with increased risk for venous thrombosis, its association with ischemic stroke in young adults remains uncertain. Therefore, we examined the association between FVL and ischemic stroke in participants of the Genetics of Early Onset Stroke (GEOS) study. A population-based case control study identified 354 women and 476 men 15 to 49 years of age with first-ever ischemic stroke and 907 controls. Participant-specific data included vascular risk factors, FVL genotype and, for cases, the ischemic stroke subtype by modified Trial of ORG 10172 in Acute Stroke criteria. Logistic regression was used to calculate odds ratios for the entire population and for subgroups stratified by risk factors and ischemic stroke subtype. The frequency of the FVL mutation was similar between ischemic stroke patients (3.6%; 95% confidence interval [CI] 2.5%-5.1%) and nonstroke controls (3.8%; 95% CI 2.7%-5.2%). This frequency did not change significantly when cases were restricted to patients with stroke of undetermined etiology (4.1%; 95% CI 2.6%-6.4%). Among young adults, we found no evidence for an association between FVL and either all ischemic stroke or the subgroup with stroke of undetermined etiology. Published by Elsevier Inc.

Minocycline treatment in acute stroke: an open-label, evaluator-blinded study.

Science.gov (United States)

Lampl, Y; Boaz, M; Gilad, R; Lorberboym, M; Dabby, R; Rapoport, A; Anca-Hershkowitz, M; Sadeh, M

2007-10-02

Ischemic animal model studies have shown a neuroprotective effect of minocycline. To analyze the effect of minocycline treatment in human acute ischemic stroke. We performed an open-label, evaluator-blinded study. Minocycline at a dosage of 200 mg was administered orally for 5 days. The therapeutic window of time was 6 to 24 hours after onset of stroke. Data from NIH Stroke Scale (NIHSS), modified Rankin Scale (mRS), and Barthel Index (BI) were evaluated. The primary objective was to compare changes from baseline to day 90 in NIHSS in the minocycline group vs placebo. One hundred fifty-two patients were included in the study. Seventy-four patients received minocycline treatment, and 77 received placebo. NIHSS and mRS were significantly lower and BI scores were significantly higher in minocycline-treated patients. This pattern was already apparent on day 7 and day 30 of follow-up. Deaths, myocardial infarctions, recurrent strokes, and hemorrhagic transformations during follow-up did not differ by treatment group. Patients with acute stroke had significantly better outcome with minocycline treatment compared with placebo. The findings suggest a potential benefit of minocycline in acute ischemic stroke.

Engineering scale tests of mechanical disassembly and short stroke shearing systems for FBR fuel assembly

International Nuclear Information System (INIS)

Higuchi, Hidetoshi; Kitagaki, Toru; Koizumi, Kenji; Hirano, Hiroyasu; Takeuchi, Masayuki; Washiya, Tadahiro; Kawabe, Yukinari; Kobayashi, Tsuguyuki

2011-01-01

Japan Atomic Energy Agency (JAEA) and The Japan Atomic Power Company (JAPC) have been developing an advanced head-end process based on mechanical disassembly and short stroke shearing systems as a part of Fast Reactor Cycle Technology Development (FaCT). Fuel pins for a fast reactor are installed within a hexagonal shaped wrapper tube made of stainless steel. In order to reprocess the fast reactor fuel pins, they must be removed from the wrapper tube and transported to the shearing system without failure. In addition, the advanced aqueous reprocessing process, called 'NEXT' (New Extraction System for TRU Recovery) process requires a solution of the spent fuel with relatively high concentration (500g/L). JAEA and JAPC have developed the mechanical disassembly and the short stroke shearing technology which is expected to make fragmented fuel to satisfy these requirements. This paper reports the results of engineering scale tests on the mechanical disassembly and short stroke shearing systems. These tests were carried out with simulated FBR fuel assembly and removed pins. The mechanical cutting method has been developed to avoid fuel pin failure during disassembly operation. The cutting process is divided into two modes, so called 'slit-cut' for cutting the wrapper tube and 'crop-cut' for the end plug region of the fuel pin bundle. In the slit-cut mode, the depth of cutting was automatically controlled based on the calculated wastage of the cutting tool and deformation of the wrapper tube which had been measured before the cutting. This procedure was confirmed to minimize the fuel pin failure which was hard to prevent in the case of laser cutting. The cutting speed was also controlled automatically by the electric current of the cutting motor to lower the load of the cutting tool. The removed fuel pins were transported to the shearing machine, whose fuel shearing magazine width was set to be narrow to realize the suitable configuration for the short stroke shearing

Increased risk of ischemic stroke in cervical cancer patients: a nationwide population-based study

International Nuclear Information System (INIS)

Tsai, Shiang-Jiun; Su, Yu-Chieh; Hung, Shih-Kai; Huang, Yung-Sung; Tung, Chien-Hsueh; Lee, Ching-Chih; Lee, Moon-Sing; Chiou, Wen-Yen; Lin, Hon-Yi; Hsu, Feng-Chun; Tsai, Chih-Hsin

2013-01-01

Increased risk of ischemic stroke has been validated for several cancers, but limited study evaluated this risk in cervical cancer patients. Our study aimed to evaluate the risk of ischemic stroke in cervical cancer patients. The study analyzed data from the 2003 to 2008 National Health Insurance Research Database (NHIRD) provided by the National Health Research Institutes in Taiwan. Totally, 893 cervical cancer patients after radiotherapy and 1786 appendectomy patients were eligible. The Kaplan-Meier method and the Cox proportional hazards model were used to assess the risk of ischemic stroke. The 5-year cumulative risk of ischemic stroke was significantly higher for the cervical cancer group than for the control group (7.8% vs 5.1%; p <0.005). The risk of stroke was higher in younger (age <51 years) than in older (age ≥51 years) cervical cancer patients (HR = 2.73, p = 0.04; HR = 1.37, p = 0.07) and in patients with more than two comorbid risk factors (5 years cumulative stroke rate of two comorbidities: 15% compared to no comorbidities: 4%). These study demonstrated cervical cancer patients had a higher risk of ischemic stroke than the general population, especially in younger patients. Strategies to reduce this risk should be assessed

Study of two-stage turbine characteristic and its influence on turbo-compound engine performance

International Nuclear Information System (INIS)

Zhao, Rongchao; Zhuge, Weilin; Zhang, Yangjun; Yang, Mingyang; Martinez-Botas, Ricardo; Yin, Yong

2015-01-01

Highlights: • An analytical model was built to study the interactions between two turbines in series. • The impacts of HP VGT and LP VGT on turbo-compound engine performance were investigated. • The fuel reductions obtained by HP VGT at 1900 rpm and 1000 rpm are 3.08% and 7.83% respectively. • The optimum value of AR ranged from 2.0 to 2.5 as the turbo-compound engine speed decreases. - Abstract: Turbo-compounding is an effective way to recover waste heat from engine exhaust and reduce fuel consumption for internal combustion engine (ICE). The characteristics of two-stage turbine, including turbocharger turbine and power turbine, have significant effects on the overall performance of turbo-compound engine. This paper investigates the interaction between two turbines in a turbo-compound engine and its impact on the engine performance. Firstly an analytical model is built to investigate the effects of turbine equivalent flow area on the two-stage turbine characteristics, including swallowing capacity and load split. Next both simulation and experimental method are carried out to study the effects of high pressure variable geometry turbine (HP VGT), low pressure variable geometry turbine (LP VGT) and combined VGT on the engine overall performance. The results show that the engine performance is more sensitive to HP VGT compared with LP VGT at all the operation conditions, which is caused by the larger influences of HP VGT on the total expansion ratio and engine air–fuel ratio. Using the HP VGT method, the fuel reductions of the turbo-compound engine at 1900 rpm and 1000 rpm are 3.08% and 7.83% respectively, in comparison with the baseline engine. The corresponding optimum values of AR are 2.0 and 2.5

Acupuncture intervention in ischemic stroke: a randomized controlled prospective study.

Science.gov (United States)

Shen, Peng-Fei; Kong, Li; Ni, Li-Wei; Guo, Hai-Long; Yang, Sha; Zhang, Li-Li; Zhang, Zhi-Long; Guo, Jia-Kui; Xiong, Jie; Zhen, Zhong; Shi, Xue-Min

2012-01-01

Stroke is one of the most common causes of death and few pharmacological therapies show benefits in ischemic stroke. In this study, 290 patients aged 40-75 years old with first onset of acute ischemic stroke (more than 24 hours but within 14 days) were treated with standard treatments, and then were randomly allocated into an intervention group (treated with resuscitating acupuncture) and a control group (treated using sham-acupoints). Primary outcome measures included Barthel Index (BI), relapse and death up to six months. For the 290 patients in both groups, one case in the intervention group died, and two cases in the control group died from the disease (p = 0.558). Six patients of the 144 cases in the intervention group had relapse, whereas 34 of 143 patients had relapse in the control group (p two groups, respectively (p two groups for the National Institute of Health Stroke Scale (NIHSS), not at two weeks (7.03 ± 3.201 vs. 8.13 ± 3.634; p = 0.067), but at four weeks (4.15 ± 2.032 vs. 6.35 ± 3.131, p Stroke Scale (CSS) at four weeks showed more improvement in the intervention group than that in the control group (9.40 ± 4.51 vs. 13.09 ± 5.80, p Stroke Specific Quality of Life Scale (SS-QOL) at six months was higher in the intervention group (166.63 ± 45.70) than the control group (143.60 ± 50.24; p < 0.01). The results of this clinical trial showed a clinically relevant decrease of relapse in patients treated with resuscitating acupuncture intervention by the end of six months, compared with needling at the sham-acupoints. The resuscitating acupuncture intervention could also improve self-care ability and quality of life, evaluated with BI, NIHSS, CSS, Oxford Handicap Scale (OHS), and SS-QOL.

Self-Reported Stroke Risk Stratification: Reasons for Geographic and Racial Differences in Stroke Study.

Science.gov (United States)

Howard, George; McClure, Leslie A; Moy, Claudia S; Howard, Virginia J; Judd, Suzanne E; Yuan, Ya; Long, D Leann; Muntner, Paul; Safford, Monika M; Kleindorfer, Dawn O

2017-07-01

The standard for stroke risk stratification is the Framingham Stroke Risk Function (FSRF), an equation requiring an examination for blood pressure assessment, venipuncture for glucose assessment, and ECG to determine atrial fibrillation and heart disease. We assess a self-reported stroke risk function (SRSRF) to stratify stroke risk in comparison to the FSRF. Participants from the REGARDS study (Reasons for Geographic and Racial Differences in Stroke) were evaluated at baseline and followed for incident stroke. The FSRF was calculated using directly assessed stroke risk factors. The SRSRF was calculated from 13 self-reported questions to exclude those with prevalent stroke and assess stroke risk. Proportional hazards analysis was used to assess incident stroke risk using the FSRF and SRSRF. Over an average 8.2-year follow-up, 939 of 23 983 participants had a stroke. The FSRF and SRSRF produced highly correlated risk scores ( r Spearman =0.852; 95% confidence interval, 0.849-0.856); however, the SRSRF had higher discrimination of stroke risk than the FSRF (c SRSRF =0.7266; 95% confidence interval, 0.7076-0.7457; c FSRF =0.7075; 95% confidence interval, 0.6877-0.7273; P =0.0038). The 10-year stroke risk in the highest decile of predicted risk was 11.1% for the FSRF and 13.4% for the SRSRF. A simple self-reported questionnaire can be used to identify those at high risk for stroke better than the gold standard FSRF. This instrument can be used clinically to easily identify individuals at high risk for stroke and also scientifically to identify a subpopulation enriched for stroke risk. © 2017 American Heart Association, Inc.

A cluster-randomised quality improvement study to improve two inpatient stroke quality indicators.

Science.gov (United States)

Williams, Linda; Daggett, Virginia; Slaven, James E; Yu, Zhangsheng; Sager, Danielle; Myers, Jennifer; Plue, Laurie; Woodward-Hagg, Heather; Damush, Teresa M

2016-04-01

Quality indicator collection and feedback improves stroke care. We sought to determine whether quality improvement training plus indicator feedback was more effective than indicator feedback alone in improving inpatient stroke indicators. We conducted a cluster-randomised quality improvement trial, randomising hospitals to quality improvement training plus indicator feedback versus indicator feedback alone to improve deep vein thrombosis (DVT) prophylaxis and dysphagia screening. Intervention sites received collaborative-based quality improvement training, external facilitation and indicator feedback. Control sites received only indicator feedback. We compared indicators pre-implementation (pre-I) to active implementation (active-I) and post-implementation (post-I) periods. We constructed mixed-effect logistic models of the two indicators with a random intercept for hospital effect, adjusting for patient, time, intervention and hospital variables. Patients at intervention sites (1147 admissions), had similar race, gender and National Institutes of Health Stroke Scale scores to control sites (1017 admissions). DVT prophylaxis improved more in intervention sites during active-I period (ratio of ORs 4.90, pimproved similarly in both groups during active-I, but control sites improved more in post-I period (ratio of ORs 0.67, p=0.04). In logistic models, the intervention was independently positively associated with DVT performance during active-I period, and negatively associated with dysphagia performance post-I period. Quality improvement training was associated with early DVT improvement, but the effect was not sustained over time and was not seen with dysphagia screening. External quality improvement programmes may quickly boost performance but their effect may vary by indicator and may not sustain over time. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Biomarkers of Acute Stroke Etiology (BASE) Study Methodology.

Science.gov (United States)

Jauch, Edward C; Barreto, Andrew D; Broderick, Joseph P; Char, Doug M; Cucchiara, Brett L; Devlin, Thomas G; Haddock, Alison J; Hicks, William J; Hiestand, Brian C; Jickling, Glen C; June, Jeff; Liebeskind, David S; Lowenkopf, Ted J; Miller, Joseph B; O'Neill, John; Schoonover, Tim L; Sharp, Frank R; Peacock, W Frank

2017-05-05

Acute ischemic stroke affects over 800,000 US adults annually, with hundreds of thousands more experiencing a transient ischemic attack. Emergent evaluation, prompt acute treatment, and identification of stroke or TIA (transient ischemic attack) etiology for specific secondary prevention are critical for decreasing further morbidity and mortality of cerebrovascular disease. The Biomarkers of Acute Stroke Etiology (BASE) study is a multicenter observational study to identify serum markers defining the etiology of acute ischemic stroke. Observational trial of patients presenting to the hospital within 24 h of stroke onset. Blood samples are collected at arrival, 24, and 48 h later, and RNA gene expression is utilized to identify stroke etiology marker candidates. The BASE study began January 2014. At the time of writing, there are 22 recruiting sites. Enrollment is ongoing, expected to hit 1000 patients by March 2017. The BASE study could potentially aid in focusing the initial diagnostic evaluation to determine stroke etiology, with more rapidly initiated targeted evaluations and secondary prevention strategies.Clinical Trial Registration Clinicaltrials.gov NCT02014896 https://clinicaltrials.gov/ct2/show/NCT02014896?term=biomarkers+of+acute+stroke+etiology&rank=1.

Estrogen-IGF-1 interactions in neuroprotection: Ischemic Stroke as a case study

Science.gov (United States)

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

Relationship between functional disability and costs one and two years post stroke

Science.gov (United States)

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

Relationship between functional disability and costs one and two years post stroke.

Directory of Open Access Journals (Sweden)

Ingrid Lekander

Full Text Available 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.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.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.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.

Returning to paid employment after stroke: the Psychosocial Outcomes In StrokE (POISE cohort study.

Directory of Open Access Journals (Sweden)

Maree L Hackett

Full Text Available OBJECTIVES: To determine which early modifiable factors are associated with younger stroke survivors' ability to return to paid work in a cohort study with 12-months of follow-up conducted in 20 stroke units in the Stroke Services NSW clinical network. PARTICIPANTS: Were aged >17 and <65 years, recent (within 28 days stroke, able to speak English sufficiently to respond to study questions, and able to provide written informed consent. Participants with language or cognitive impairment were eligible to participate if their proxy provided consent and completed assessments on the participants' behalf. The main outcome measure was return to paid work during the 12 months following stroke. RESULTS: Of 441 consented participants (average age 52 years, 68% male, 83% with ischemic stroke, 218 were in paid full-time and 53 in paid part-time work immediately before their stroke, of whom 202 (75% returned to paid part- or full-time work within 12 months. Being male, female without a prior activity restricting illness, younger, independent in activities of daily living (ADL at 28 days after stroke, and having private health insurance was associated with return to paid work, following adjustment for other illnesses and a history of depression before stroke (C statistic 0·81. Work stress and post stroke depression showed no such independent association. CONCLUSIONS: Given that independence in ADL is the strongest predictor of return to paid work within 12 months of stroke, these data reinforce the importance of reducing stroke-related disability and increasing independence for younger stroke survivors. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry ANZCTRN 12608000459325.

The use of modal derivatives in determining stroke-dependent frequencies of large stroke flexure hinges

NARCIS (Netherlands)

van den Belt, Mieke; Schilder, Jurnan; Valasek, Michael; Sika, Zbynek; Vampola, Tomas

2017-01-01

Nowadays, a lot of use is made of large stroke flexure hinges in precision engineering. However, these large stroke flexure hinges typically lose stiffness in supporting direction during deflection. The lowest natural frequency is a commonly used measure for this property. Therefore, in shape and

Strokes Associated With Pregnancy and Puerperium: A Nationwide Study by the Japan Stroke Society.

Science.gov (United States)

Yoshida, Kazumichi; Takahashi, Jun C; Takenobu, Yohei; Suzuki, Norihiro; Ogawa, Akira; Miyamoto, Susumu

2017-02-01

The incidence and cause of strokes associated with pregnancy and the puerperium are still not fully understood. The aim of this study was to characterize pregnancy-related strokes in Japan using a large-scale survey with current imaging techniques. A retrospective analysis was conducted based on clinical chart reviews in 736 stroke teaching hospitals certified by the Japan Stroke Society between 2012 and 2013, using a web-based questionnaire requesting the detailed clinical course without any personally identifying information. The collection rate of this questionnaire was 70.5%, with 151 pregnancy-associated strokes extracted. Hemorrhagic strokes were observed in 111 cases (73.5%), ischemic strokes in 37 (24.5%), and mixed type in 3 cases (2.0%). The estimated incidence of pregnancy-associated stroke was 10.2 per 100 000 deliveries. Major causes of hemorrhage were aneurysm (19.8%), arteriovenous malformation (17.1%), pregnancy-induced hypertension (11.7%), and HELLP syndrome (hemolysis, elevated liver enzymes, and low platelet count) (8.1%). Preexisting cerebrovascular diseases responsible for hemorrhage were detected in 59 cases (53.1%). Among the ischemic strokes, 28 (75.7%) were arterial and 9 (24.3%) were venous infarctions. The most frequent cause of arterial infarctions was reversible cerebral vasoconstriction syndrome. Hemorrhagic stroke showed much poorer prognosis than ischemic stroke. The incidence of pregnancy-associated stroke in Japan did not seem higher than that in other Asian and Western countries. The proportion of hemorrhagic stroke among Japanese women was much higher than that in white women. Preexisting cerebrovascular diseases and reversible cerebral vasoconstriction syndrome play a key role in hemorrhagic and ischemic stroke, respectively. © 2016 American Heart Association, Inc.

Diesel engines for independent power producers

International Nuclear Information System (INIS)

Berc, Dj.

1999-01-01

During recent years an increasing demand has been experienced in the stationary diesel engine market for 10-70 MW diesel units. For larger units this demand is being met by two-stroke low-speed crosshead uniflow scavenged diesel engines, capable of burning almost any fuel available on the market, both liquid of gaseous. The paper deals with service experience gained from such engines and their fuel capability. Examples of actual installations for IPPs and captive plants, together with an example of a typical feasibility study of such plants, is presented in the Appendix. (author)

Free piston variable-stroke linear-alternator generator

Science.gov (United States)

Haaland, Carsten M.

1998-01-01

A free-piston variable stroke linear-alternator AC power generator for a combustion engine. An alternator mechanism and oscillator system generates AC current. The oscillation system includes two oscillation devices each having a combustion cylinder and a flying turnbuckle. The flying turnbuckle moves in accordance with the oscillation device. The alternator system is a linear alternator coupled between the two oscillation devices by a slotted connecting rod.

A prediction study of a spark ignition supercharged hydrogen engine

International Nuclear Information System (INIS)

Al-Baghdadi, Maher A.R. Sadiq.; Al-Janabi, Haroun A.K. Shahad

2003-01-01

Hydrogen is found to be a suitable alternative fuel for spark ignition engines with certain drawbacks, such as high NO x emission and small power output. However, supercharging may solve such problems. In this study, the effects of equivalence ratio, compression ratio and inlet pressure on the performance and NO x emission of a four stroke supercharged hydrogen engine have been analyzed using a specially developed computer program. The results are verified and compared with experimental data obtained from tests on a Ricardo E6/US engine. A chart specifying the safe operation zone of the hydrogen engine has been produced. The safe operation zone means no pre-ignition, acceptable NO x emission, high engine efficiency and lower specific fuel consumption in comparison with the gasoline engine. The study also shows that supercharging is a more effective method to increase the output of a hydrogen engine rather than increasing the compression ratio of the engine at the knock limited equivalence ratio

A prediction study of a spark ignition supercharged hydrogen engine

Energy Technology Data Exchange (ETDEWEB)

Al-Baghdadi, M.A.R.S.; Al-Janabi, H.A.K.S. [University of Babylon (Iraq). Dept. of Mechanical Engineering

2003-12-01

Hydrogen is found to be a suitable alternative fuel for spark ignition engines with certain drawbacks, such as high NO{sub x} emission and small power output. However, supercharging may solve such problems. In this study, the effects of equivalence ratio, compression ratio and inlet pressure on the performance and NO{sub x} emission of a four stroke supercharged hydrogen engine have been analyzed using a specially developed computer program. The results are verified and compared with experimental data obtained from tests on a Ricardo E6/US engine. A chart specifying the safe operation zone of the hydrogen engine has been produced. The safe operation zone means no pre-ignition, acceptable NO{sub x} emission, high engine efficiency and lower specific fuel consumption in comparison with the gasoline engine. The study also shows that supercharging is a more effective method to increase the output of a hydrogen engine rather than increasing the compression ratio of the engine at the knock limited equivalence ratio. (author)

The Christchurch earthquake stroke incidence study.

Science.gov (United States)

Wu, Teddy Y; Cheung, Jeanette; Cole, David; Fink, John N

2014-03-01

We examined the impact of major earthquakes on acute stroke admissions by a retrospective review of stroke admissions in the 6 weeks following the 4 September 2010 and 22 February 2011 earthquakes. The control period was the corresponding 6 weeks in the previous year. In the 6 weeks following the September 2010 earthquake there were 97 acute stroke admissions, with 79 (81.4%) ischaemic infarctions. This was similar to the 2009 control period which had 104 acute stroke admissions, of whom 80 (76.9%) had ischaemic infarction. In the 6 weeks following the February 2011 earthquake, there were 71 stroke admissions, and 61 (79.2%) were ischaemic infarction. This was less than the 96 strokes (72 [75%] ischaemic infarction) in the corresponding control period. None of the comparisons were statistically significant. There was also no difference in the rate of cardioembolic infarction from atrial fibrillation between the study periods. Patients admitted during the February 2011 earthquake period were less likely to be discharged directly home when compared to the control period (31.2% versus 46.9%, p=0.036). There was no observable trend in the number of weekly stroke admissions between the 2 weeks leading to and 6 weeks following the earthquakes. Our results suggest that severe psychological stress from earthquakes did not influence the subsequent short term risk of acute stroke, but the severity of the earthquake in February 2011 and associated civil structural damages may have influenced the pattern of discharge for stroke patients. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effectiveness of two rehabilitation strategies provided by nurses for stroke patients in Mexico.

Science.gov (United States)

Torres-Arreola, Laura del Pilar; Doubova Dubova, Svetlana Vladislavovna; Hernandez, Sergio F; Torres-Valdez, Laura E; Constantino-Casas, Norma P; Garcia-Contreras, Fernando; Torres-Castro, Sara

2009-11-01

Rehabilitation strategies have been developed to improve functional state in stroke patients. The main objective of this study was to evaluate the effectiveness of the early rehabilitation at hospital and its continuity at home provided by nurses, on the functional recovery of basic and social activities in stroke patients compared with conventional care. A randomised clinical trial was carried out in three general hospitals of the Mexican Institute of Social Security (IMSS) in Mexico City between April 2003-May 2004. Stroke patients. Two rehabilitation strategies provided by nurses for stroke patients were compared: physiotherapy plus caregiver education in rehabilitation (strategy 1, S1) vs. education alone (strategy 2, S2). The main outcome variables were the basic (Barthel index) and social (Frenchay activities index) activities of daily living, of each patient. Age, sex, morbidity, stroke symptoms, complications, neurological damage (Canadian Scale), cognitive state (mini-mental state examination questionnaire) and duration of hospitalisation were defined as the control variables. Patients were evaluated at baseline and months one, three and six thereafter. One hundred and ten patients with ischaemic stroke were enrolled and randomised; 59 were assigned to S1 and 51 to S2. Comparison of the outcome variables showed that patients improved significantly over time, but no differences were observed between groups. We observed no significant difference in strategy performance with regard to the basic and instrumental activities of daily living. Participants who received physiotherapy with additional caregiver education benefit no more than those whose caregivers received education alone. Those countries that do not have integral rehabilitation programmes for stroke patients should understand their importance and budget resources for them. Meanwhile, both caregiver education and nurses trained in specific care and physiotherapy are alternatives that benefit these

Incidence of stroke in women in Auckland, New Zealand. Ethnic trends over two decades: 1981-2003.

Science.gov (United States)

Dyall, Lorna; Carter, Kristie; Bonita, Ruth; Anderson, Craig; Feigin, Valery; Kerse, Ngaire; Brown, Paul

2006-11-17

Although women have a greater lifetime risk of stroke than men, along with other gender differences in stroke, there is lack of reliable data on long-term trends in stroke in women. This paper presents the results of three population-based registers in Auckland (1981-1982, 1991-1992, and 2002-2003) which aimed to determine the trends in the incidence of stroke in New Zealand. This paper reports on the burden of stroke in women across different ethnic groups over the study period from 1981 to 2003. Three studies using similar methodology and overlapping case finding methods have been conducted in New Zealand to estimate trends in the incidence and outcome of stroke. The studies are recognised as meeting the 'ideal' criteria for stroke incidence and identify all first-ever and recurrent strokes in residents (aged greater than and equal to 15 years) the population of Auckland, New Zealand in the 12-month periods from 1981-1982, 1991-1992, and 2002-2003. There were totals of 307,578 strokes among women in 1981, 372,642 in 1991, and 470,727 in 2001, according to each Census representing over 50% of the population at each period (51%-54%). The WHO standard world population was used for direct age standardisation of annual rates (per 100,000 population), reported with 95% confidence intervals (CI). The proportion of women who have experienced a stroke did not change markedly over the study period but there were ethnic differences emerging which were related to population changes within the New Zealand population. Standardised stroke incidence in women was relatively stable across the three study periods (1981-1982), 133 [95% CI 118-151]; (1991-1992), 143 [95% CI 116-241]; and (2002-2003), 124 [95% CI 115-134]). However, a significant decline of 14% (95% CI 2%-29%) in rates of first-ever stroke was found between 1991-1992 and 2002-2003 in women. In contrast to the significant declines in event rates in European women over two decades (Rate ratio 0.84, 95% CI 0

Dynamics of the inlet system of a four-stroke engine

Science.gov (United States)

Boden, R H; Schecter, Harry

1944-01-01

Tests were run on a single-cylinder and a multicylinder four-stroke engine in order to determine the effect of the dynamics of the inlet system upon indicated mean effective pressure. Tests on the single-cylinder engine were made at various speeds, inlet valve timings, and inlet pipe lengths. These tests indicated that the indicated mean effective pressure could be raised considerably at any one speed by the use of a suitably long inlet pipe. Tests at other speeds with this length of pipe showed higher indicated mean effective pressure than with a very short pipe, although not so high as could be obtained with the pipe length adjusted for each speed. A general relation was discovered between optimum time of inlet valve closing and pipe length; namely, that longer pipes require later inlet valve closing in order to be fully effective. Tests were also made on three cylinders connected to a single pipe. With this arrangement, increased volumetric efficiency at low speed was obtainable by using a long pipe, but only with a sacrifice of volumetric efficiency at high speed. Volumetric efficiency at high speed was progressively lower as the pipe length was increased.

Stroke risk perception among participants of a stroke awareness campaign

Science.gov (United States)

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

Telestroke ambulances in prehospital stroke management: concept and pilot feasibility study.

Science.gov (United States)

Liman, Thomas G; Winter, Benjamin; Waldschmidt, Carolin; Zerbe, Norman; Hufnagl, Peter; Audebert, Heinrich J; Endres, Matthias

2012-08-01

Pre- and intrahospital time delays are major concerns in acute stroke care. Telemedicine-equipped ambulances may improve time management and identify patients with stroke eligible for thrombolysis by an early prehospital stroke diagnosis. The aims of this study were (1) to develop a telestroke ambulance prototype; (2) to test the reliability of stroke severity assessment; and (3) to evaluate its feasibility in the prehospital emergency setting. Mobil, real-time audio-video streaming telemedicine devices were implemented into advanced life support ambulances. Feasibility of telestroke ambulances and reliability of the National Institutes of Health Stroke Scale assessment were tested using current wireless cellular communication technology (third generation) in a prehospital stroke scenario. Two stroke actors were trained in simulation of differing right and left middle cerebral artery stroke syndromes. National Institutes of Health Stroke Scale assessment was performed by a hospital-based stroke physician by telemedicine, by an emergency physician guided by telemedicine, and "a posteriori" on the basis of video documentation. In 18 of 30 scenarios, National Institutes of Health Stroke Scale assessment could not be performed due to absence or loss of audio-video signal. In the remaining 12 completed scenarios, interrater agreement of National Institutes of Health Stroke Scale examination between ambulance and hospital and ambulance and "a posteriori" video evaluation was moderate to good with weighted κ values of 0.69 (95% CI, 0.51-0.87) and 0.79 (95% CI, 0.59-0.98), respectively. Prehospital telestroke examination was not at an acceptable level for clinical use, at least on the basis of the used technology. Further technical development is needed before telestroke is applicable for prehospital stroke management during patient transport.

Sex Differences in Stroke Survival: 10-Year Follow-up of the Copenhagen Stroke Study Cohort

DEFF Research Database (Denmark)

Andersen, Morten Nonboe; Andersen, Klaus Kaae; Kammersgaard, Lars Peter

2005-01-01

BACKGROUND: Although diverging, most studies show that sex has no significant influence on stroke survival. METHODS: In a Copenhagen, Denmark, community all patients with stroke during March 1992 to November 1993 were registered on hospital admission. Stroke severity was measured using the Scandi......BACKGROUND: Although diverging, most studies show that sex has no significant influence on stroke survival. METHODS: In a Copenhagen, Denmark, community all patients with stroke during March 1992 to November 1993 were registered on hospital admission. Stroke severity was measured using......-up period. Predictors of death were identified using a Cox proportional hazards model. RESULTS: Of 999 patients, 559 (56%) were women and 440 (44%) were men. Women were older (77.0 v 70.9 years; P ... factors showed no difference between sexes for ischemic heart disease, hypertension, atrial fibrillation, diabetes mellitus, and previous stroke. Men more often were smokers and alcohol consumers. Unadjusted survival in men and women did not differ: 70.3% versus 66.7% (1-year), 40.0% versus 38.9% (5-year...

Sex differences in stroke survival: 10-year follow-up of the Copenhagen stroke study cohort

DEFF Research Database (Denmark)

Andersen, Morten Nonboe; Andersen, Klaus Kaae; Kammersgaard, Lars Peter

2005-01-01

BACKGROUND: Although diverging, most studies show that sex has no significant influence on stroke survival. METHODS: In a Copenhagen, Denmark, community all patients with stroke during March 1992 to November 1993 were registered on hospital admission. Stroke severity was measured using the Scandi......BACKGROUND: Although diverging, most studies show that sex has no significant influence on stroke survival. METHODS: In a Copenhagen, Denmark, community all patients with stroke during March 1992 to November 1993 were registered on hospital admission. Stroke severity was measured using......-up period. Predictors of death were identified using a Cox proportional hazards model. RESULTS: Of 999 patients, 559 (56%) were women and 440 (44%) were men. Women were older (77.0 v 70.9 years; P ... factors showed no difference between sexes for ischemic heart disease, hypertension, atrial fibrillation, diabetes mellitus, and previous stroke. Men more often were smokers and alcohol consumers. Unadjusted survival in men and women did not differ: 70.3% versus 66.7% (1-year), 40.0% versus 38.9% (5-year...

Migraine and risk of stroke and acute coronary syndrome in two case-control studies in the Danish population

DEFF Research Database (Denmark)

Osler, Merete; Wium-Andersen, Ida Kim; Jørgensen, Martin Balslev

2017-01-01

INTRODUCTION: Migraine has consistently been associated with increased risk of ischemic stroke, while the evidence for a relation with other types of stroke or coronary outcomes is limited. We examined the association between migraine and stroke and acute coronary syndrome (ACS) subtypes and the ......INTRODUCTION: Migraine has consistently been associated with increased risk of ischemic stroke, while the evidence for a relation with other types of stroke or coronary outcomes is limited. We examined the association between migraine and stroke and acute coronary syndrome (ACS) subtypes...... medication had increased ORs of all stroke subtypes (ischemic, hemorrhagic stroke and transient ischemic attacks). The diagnosis of migraine was also associated with both angina and myocardial infarction (ST-elevation Myocardial Infarction [STEMI], non-STEMI and unspecified) with the highest OR for angina...

Linear engine development for series hybrid electric vehicles

Science.gov (United States)

Toth-Nagy, Csaba

This dissertation argues that diminishing oil reserves, concern over global climate change, and desire to improve ambient air quality all demand the development of environment-friendly personal transportation. In certain applications, series hybrid electric vehicles offer an attractive solution to reducing fuel consumption and emissions. Furthermore, linear engines are emerging as a powerplant suited to series HEV applications. In this dissertation, a linear engine/alternator was considered as the auxiliary power unit of a range extender series hybrid electric vehicle. A prototype linear engine/alternator was developed, constructed and tested at West Virginia University. The engine was a 2-stroke, 2-cylinder, dual piston, direct injection, diesel engine. Experiment on the engine was performed to study its behavior. The study variables included mass of the translator, amount of fuel injected, injection timing, load, and stroke with operating frequency and mechanical efficiency as the basis of comparison. The linear engine was analyzed in detail and a simple simulation model was constructed to compare the trends of simulation with the experimental data and to expand on the area where the experimental data were lacking. The simulation was based on a simple and analytical model, rather than a detailed and intensely numerical one. The experimental and theoretical data showed similar trends. Increasing translator mass decreased the operating frequency and increased compression ratio. Larger mass and increased compression ratio improved the ability of the engine to sustain operation and the engine was able to idle on less fuel injected into the cylinder. Increasing the stroke length caused the operating frequency to drop. Increasing fueling or decreasing the load resulted in increased operating frequency. This projects the possibility of using the operating frequency as an input for feedback control of the engine. Injection timing was varied to investigate two different

Mathematical Modelling of a Hybrid Micro-Cogeneration Group Based on a Four Stroke Diesel Engine

Directory of Open Access Journals (Sweden)

Apostol Valentin

2014-06-01

Full Text Available The paper presents a part of the work conducted in the first stage of a Research Grant called ”Hybrid micro-cogeneration group of high efficiency equipped with an electronically assisted ORC” acronym GRUCOHYB. The hybrid micro-cogeneration group is equipped with a four stroke Diesel engine having a maximum power of 40 kW. A mathematical model of the internal combustion engine is presented. The mathematical model is developed based on the Laws of Thermodynamics and takes into account the real, irreversible processes. Based on the mathematical model a computation program was developed. The results obtained were compared with those provided by the Diesel engine manufacturer. Results show a very high correlation between the manufacturer’s data and the simulation results for an engine running at 100% load. Future developments could involve using an exergetic analysis to show the ability of the ORC to generate electricity from recovered heat

Diesel Engine Tribology

DEFF Research Database (Denmark)

Christiansen, Christian Kim

Recent years have seen an increase in the wear rate of engine bearings, subsequently followed by bearing failure, for the large two-stroke diesel engines used for ship propulsion. Here, the engine bearings include main, big end and crosshead bearings, with the bearing type used being the journal...... bearing, belonging to the class of ‘hydrodynamic bearings’. This implies that the load carrying capacity is generated by a relative movement of the involved components, i.e. avelocity-driven operation. For the engine application, the velocity stems from the engine RPM. However, to comply with the latest...

Neuroserpin polymorphisms and stroke risk in a biracial population: the stroke prevention in young women study

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Stern Barney J

2007-10-01

Full Text Available Abstract Background Neuroserpin, primarily localized to CNS neurons, inhibits the adverse effects of tissue-type plasminogen activator (tPA on the neurovascular unit and has neuroprotective effects in animal models of ischemic stroke. We sought to evaluate the association of neuroserpin polymorphisms with risk for ischemic stroke among young women. Methods A population-based case-control study of stroke among women aged 15–49 identified 224 cases of first ischemic stroke (47.3% African-American and 211 age-matched control subjects (43.1% African-American. Neuroserpin single nucleotide polymorphisms (SNPs chosen through HapMap were genotyped in the study population and assessed for association with stroke. Results Of the five SNPs analyzed, the A allele (frequency; Caucasian = 0.56, African-American = 0.42 of SNP rs6797312 located in intron 1 was associated with stroke in an age-adjusted dominant model (AA and AT vs. TT among Caucasians (OR = 2.05, p = 0.023 but not African-Americans (OR = 0.71, p = 0.387. Models adjusting for other risk factors strengthened the association. Race-specific haplotype analyses, inclusive of SNP rs6797312, again demonstrated significant associations with stroke among Caucasians only. Conclusion This study provides the first evidence that neuroserpin is associated with early-onset ischemic stroke among Caucasian women.

Understanding nursing practice in stroke units: a Q-methodological study.

OpenAIRE

Clarke, DJ; Holt, J

2014-01-01

Abstract Purpose: Nurses represent the largest professional group working with stroke-survivors, but there is limited evidence regarding nurses' involvement in post-stroke rehabilitation. The purpose of this study was to identify and explore the perspectives of nurses and other multidisciplinary stroke team members on nurses' practice in stroke rehabilitation. Method: Q-methodological study with 63 multidisciplinary stroke unit team members and semi-structured interviews with 27 stroke unit t...

The influence of Compression Ratio to Performance of Four Stroke Engine Use of Arak Bali as a Fuel

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I Dewa Made Krishna Muku

2012-11-01

Full Text Available Arak bali is alternative fuel as ethanol. Ethanol has octane number 108. Octane number which was higher can over come adetonation, and can work at higher compression ratio. This experiment has done to now how the effect of compression ratiovariation to the performance four strokes engine by arak bali fuel. This research was done by changing the compressionratio that is 8,8 : 1, 8,9 : 1, 9 : 1 and 9,3 : 1. The change was done by reducing combustion chamber by scrap the cylinderhead. The result, for the used arak bali fuel to the vehicle is, if engine compression ratio to increase can be influence ofengine performance to be increase and engine fuel consumption to be decrease. For premium is, if engine compression ratioto increase to influence of engine performance to be decrease and engine fuel consumption to be increase.

Young ischemic stroke in Tunisia: a multicentric study.

Science.gov (United States)

Kefi, Asma; Larbi, Thara; Abdallah, Meya; Ouni, Amira El; Bougacha, Neil; Bouslama, Kamel; Hamzaoui, Saloua; M'rad, Skander

2017-04-01

There is wanting data regarding young ischemic stroke in developing countries, especially in Tunisia. The purpose of this study was to investigate risk factors and etiologies of young ischemic stroke in Tunisian and make a comparison with previous reports. A total of 102 young ischemic stroke patients (15-45 years old) were admitted, between January 1996 and August 2007, to 11 departments of internal medicine in different Tunisian hospitals. The risk factors for stroke were documented and assessed. Diagnosis workup consisted of anamnesis, complete physical examination and extensive laboratory, radiologic, immunologic, neurologic and cardiologic examination. Stroke etiologies were classified according the Trial of ORG 10172 in acute stroke treatment. There were 42 men (41.2%) and 60 women (58.89%) with a mean age at onset of 35.7 years. As regards stroke subtype, large-artery atherosclerosis was diagnosed in 6.9% of cases, cardioembolism in 11.8%, small-vessel occlusion in 8.8%, other determined etiology in 37.3% and undetermined etiology in 35.3%. Concerning the traditional risk factors, smoking (31.4%), hypertension and diabetes mellitus (12.7% for each one) and a family history of stroke (10.8%) were the most common. The mean follow-up period was 30.5 months. In our study, traditional risk factors were not-so-uncommon in young adults with ischemic stroke suggesting that prevention can go through controlling these factors. Stroke of other determined etiology was the most common among our patients, so that a broad and detailed diagnostic workup is crucial to puzzle out the etiology for more and better stroke prevention.

Finite Element Analysis of a Four-Cylinder Four Stroke Gasoline Engine Crankshaft

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Parman Setyamartana

2014-07-01

Full Text Available Stress analysis of a crankshaft using traditional method is complicated and needs modification by considering its stress concentration factors. To solve this problem, the crankshaft strength of a four-cylinder four stroke gasoline engine is modeled and analyzed using finite element method (FEM in this paper. For this purpose, the crankshaft is modeled using CATIA software in detail. Then, the model is imported in ANSYS. In the recent software, the model is meshed into a number of finite elements. After defining the boundary and loading conditions, the stresses occur in the crankshaft are analyzed in order to identify critical locations on it.

Suboptimal lipid management before and after ischaemic stroke and TIA-the North Dublin Population Stroke Study.

Science.gov (United States)

Ní Chróinín, Danielle; Ní Chróinín, Chantelle; Akijian, Layan; Callaly, Elizabeth L; Hannon, Niamh; Kelly, Lisa; Marnane, Michael; Merwick, Áine; Sheehan, Órla; Horgan, Gillian; Duggan, Joseph; Kyne, Lorraine; Dolan, Eamon; Murphy, Seán; Williams, David; Kelly, Peter J

2018-01-24

Few population-based studies have assessed lipid adherence to international guidelines for primary and secondary prevention in stroke/transient ischaemic attack (TIA) patients. This study aims to evaluate adherence to lipid-lowering therapy (LLT) guidelines amongst patients with ischaemic stroke/TIA. Using hot and cold pursuit methods from multiple hospital/community sources, all stroke and TIA cases in North Dublin City were prospectively ascertained over a 1-year period. Adherence to National Cholesterol Education Programme (NCEP) III guidelines, before and after index ischaemic stroke/TIA, was assessed. Amongst 616 patients (428 ischaemic stroke, 188 TIA), total cholesterol was measured following the qualifying event in 76.5% (471/616) and low-density lipoprotein (LDL) in 60.1% (370/616). At initial stroke/TIA presentation, 54.1% (200/370) met NCEP III LDL goals. Compliance was associated with prior stroke (odds ratio [OR] 2.19, p = 0.02), diabetes (OR 1.91, p = 0.04), hypertension (OR 1.57, p = 0.03), atrial fibrillation (OR 1.78, p = 0.01), pre-event LLT (OR 2.85, p TIA onset, 32.7% (195/596) was on LLT. Nonetheless, LDL exceeded individual NCEP goal in 29.2% (56/192); 21.6% (53/245) warranting LLT was not on treatment prior to stroke/TIA onset. After index stroke/TIA, 75.9% (422/556) was on LLT; 15.3% (30/196) meeting NCEP III criteria was not prescribed a statin as recommended. By 2 years, actuarial survival was 72.8% and 11.9% (59/497) experienced stroke recurrence. No association was observed between initial post-event target adherence and 2-year outcomes. In this population-based study, LLT recommended by international guidelines was under-used, before and after index stroke/TIA. Strategies to improve adherence are needed.

Experimental study of dual fuel engine performance using variable LPG composition and engine parameters

International Nuclear Information System (INIS)

Elnajjar, Emad; Selim, Mohamed Y.E.; Hamdan, Mohammad O.

2013-01-01

Highlights: • The effect of using variable LPG is studied. • Five fuels with propane to butane % volume ratio are: 100-70-55-25-0. • 100% Propane composition shows the highest noise levels with similar performance. • At 45° BTDC injection timing 55% Propane LPG the only fuel experience knocking. • LPG fuels gave similar engine performance, with differences in levels of noise. - Abstract: The present work investigates experimentally the effect of LPG fuel with different composition and engine parameters on the performance of a dual compression engine. Five different blends of LPG fuels are used with Propane to Butane volume ratio of 100:0, 70:30, 55:45, 25:75, and 0:100. A single cylinder, naturally aspirated, four strokes, indirectly injected, water cooled modified Ricardo E6 engine, is used in this study. The study is carried out by measuring the cylinder pressure, engine load, engine speed, crank angle, and the fuel’s flow rate. The engine performance under variable LPG fuel composition, engine load, pilot fuel injection timing, compression ratio, pilot fuel mass and engine speed, are estimated by comparing the following engine parameters: the cylinder maximum pressure, the indicated mean effective pressure, the maximum rate of pressure rise, and the thermal efficiency. The experimental data indicates that the engine parameters are playing a major role on the engine’s performance. Different LPG fuel composition did not show a major effect on the engine efficiency but directly impacted the levels of generated combustion noise

Usability testing of two e-learning resources: methods to maximize potential for clinician use.

Science.gov (United States)

Menon, Anita; Korner-Bitensky, Nicol; Chignell, Mark; Straus, Sharon

2012-04-01

Rigorous usability testing of e-learn-ing resources is an important prerequisite to their wide-spread use among clinicians. This study demonstrates the application of an evidence-based approach to usability testing of two stroke-related e-learning resources (StrokEngine). 14 stroke rehabilitation clinicians (occupational therapists and physiotherapists) from Ontario, Canada participated in a 1.5 h in-person testing session. Clinicians navigated StrokEngine in search of information to answer questions on stroke assessment/intervention. Their search patterns were observed and clinicians provided verbal/written feedback about StrokEngine. Content analysis was used to generate themes and categorize them under two broad categories: facilitators and barriers to use. Five key facilitators and three key barriers to Strok-Engine use were identified and related to screen format, layout/organization, ease of navigation, quality of content, likelihood of using StrokEngine in the future, and system dysfunctions. All 14 clinicians were very or extremely satisfied with the layout/organization, quality and clinical relevance of the content, stating that they were likely to use StrokEngine in the future. All identified barriers from this study were addressed with website modifications in order to maximize the usability and navigability of StrokEngine. This rigorous methodology for usability testing can be applied during the design process of any e-learning resource.

One-year outcome after first-ever stroke according to stroke subtype, severity, risk factors and pre-stroke treatment. A population-based study from Tartu, Estonia.

Science.gov (United States)

Vibo, R; Kõrv, J; Roose, M

2007-04-01

The aim of the current study was to evaluate the outcome at 1 year following a first-ever stroke based on a population-based registry from 2001 to 2003 in Tartu, Estonia. The outcome of first-ever stroke was assessed in 433 patients by stroke risk factors, demographic data and stroke severity at onset using the Barthel Index (BI) score and the modified Rankin Score (mRS) at seventh day, 6 months and 1 year. Female sex, older age, blood glucose value >10 mmol/l on admission and more severe stroke on admission were the best predictors of dependency 1 year following the first-ever stroke. At 1 year, the percentage of functionally dependent patients was 20% and the survival rate was 56%. The use of antihypertensive/antithrombotic medication prior to stroke did not significantly affect the outcome. The survival rate of stroke patients in Tartu is lower compared with other studied populations. The outcome of stroke was mainly determined by the initial severity of stroke and by elevated blood glucose value on admission. Patients with untreated hypertension had more severe stroke and trend for unfavourable outcome compared with those who were on treatment.

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

Science.gov (United States)

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.

Alternative general-aircraft engines

Science.gov (United States)

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.

Correlation study on cystatin C and ischemic stroke

Directory of Open Access Journals (Sweden)

CHEN Rong-bo

2013-06-01

Full Text Available Objective To investigate the relationship between serum cystatin C (Cys C and patients with acute ischemic stroke. Methods The clinical and laboratory data of 115 patients with acute ischemic stroke and 110 controls were recorded and analyzed. Results The serum Cys C levels of patients in ischemic stroke group [(1.15 ± 0.34 mg/L] were higher than that of the control group [(0.99 ± 0.25 mg/L]. The difference between two groups was significant after correction of age and cardiovascular risk factors (t = ? 3.889, P = 0.000. It was found that age, Cys C, homocysteine (Hcy, type 2 diabetes mellitus [hemoglobin A1c (HbA1c, fructosamine (FRU], smoking, alcohol consumption, hypertension and intima-media thickness (IMT were risk factors for ischemic stroke on univariate Logistic regression analysis. The difference of serum Cys C level between the patients and controls was significant (P = 0.000, but through covariance analysis, after adjusted other risk factors, it was not significant (P = 0.875. Conclusion The serum Cys C levels of patients in ischemic stroke group is higher than the control group. It can be used as an indicator in the acute phase of ischemic stroke. The elevation of serum Cys C is a risk factor for ischemic stroke, but not an independent risk factor.

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

Science.gov (United States)

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

Common variants of ROCKs and the risk of hypertension, and stroke: Two case-control studies and a follow-up study in Chinese Han population.

Science.gov (United States)

Yang, Song; Zhao, Yanping; Tian, Yuanrui; Chen, Yanchun; Zhao, Xianghai; Li, Ying; Zhao, Hailong; Chen, Xiaotian; Zhu, Lijun; Fang, Zhengmei; Yao, YingShui; Hu, Zhibing; Shen, Chong

2018-03-01

The Rho kinases (ROCKs) are recognized as a critical regulator of vascular functions in cardiovascular disorders. It is crucial to illustrate the association of ROCKs genetic variation and hypertension and/or stroke events. Herein we aimed at investigating the association of ROCK1 and ROCK2 with hypertension and stroke in Chinese Han population. Seven tagSNPs at ROCK1 and ROCK2 were genotyped in a community-based case-control study consisting of 2012 hypertension cases and 2210 normotensive controls and 4128 subjects were further followed up. In stroke case-control study, 1471 ischemic stroke (IS) inpatients and 607 hemorrhagic stroke (HS) inpatients were collected, and 2443 age-matched controls were selected from the follow-up population. Risks were estimated as odds ratio (OR) and hazard ratio (HR) by logistic and Cox regression. The community-based case-control study didn't identify any significant tagSNPs associated with hypertension even after adjustment for covariates. The follow-up analysis showed that rs1481280 of ROCK1 significantly associated with incident hypertension (HR=1.130, P=0.048) after adjusting for covariates. rs7589629 and rs978906 of ROCK2 were significantly associated with incident IS (HR=1.373, P=0.004; HR=1.284, P=0.026) respectively. In stroke case-control study, rs288980, rs1481280 and rs7237677 were significantly associated with IS and the adjusted ORs (P values) of additive model were 0.879 (0.010), 0.895 (0.036) and 0.857 (0.002) respectively. Furthermore, rs288980, rs7237677 and rs978906 were significantly associated with HS and the adjusted ORs (P values) of additive model were 0.857 (0.025), 0.848 (0.018) and 0.856 (0.027) respectively. Our findings suggest that ROCK1 and ROCK2 contribute to the genetic susceptibility of hypertension and stroke. Copyright © 2017 Elsevier B.V. All rights reserved.

Quality of stroke care at an Irish Regional General Hospital and Stroke Rehabilitation Unit.

LENUS (Irish Health Repository)

Walsh, T

2012-01-31

BACKGROUND: Robust international data support the effectiveness of stroke unit (SU) care. Despite this, most stroke care in Ireland are provided outside of this setting. Limited data currently exist on the quality of care provided. AIM: The aim of this study is to examine the quality of care for patients with stroke in two care settings-Regional General Hospital (RGH) and Stroke Rehabilitation Unit (SRU). METHODS: A retrospective analysis of the stroke records of consecutive patients admitted to the SRU between May-November 2002 and April-November 2004 was performed applying the UK National Sentinel Audit of Stroke (NSAS) tool. RESULTS: The results of the study reveal that while SRU processes of care was 74% compliant with standards; compliance with stroke service organisational standards was only 15 and 43% in the RGH and SRU, respectively. CONCLUSION: The quality of stroke care in our area is deficient. Comprehensive reorganisation of stroke services is imperative.

Comparison of the Risk Factor Profile, Stroke Subtypes, and Outcomes Between Stroke Patients Aged 65 Years or Younger and Elderly Stroke Patients: A Hospital-based Study

Directory of Open Access Journals (Sweden)

Yi-Min Chen

2013-12-01

Conclusion: We conclude that, apart from risk factors and stroke subtypes, the functional outcomes observed in the two groups differed. Early identification of these differences with good management may help to improve the clinical outcomes in younger stroke patients.

STUDY OF ACUTE ISCHAEMIC STROKE IN ELDERLY

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Mohammed Aslam Shaikh

2017-02-01

Full Text Available BACKGROUND Stroke affects 16.9 million people annually and the greatest burden of stroke is in low- and middle-income countries where 69% of all strokes occur. Stroke risk factors, mortality and outcomes differ in developing countries as compared to the developed world. Stroke incidence increases with increasing age and has an impact on daily living in many areas with increasing life expectancy. Old people constitute the majority of stroke victims. MATERIALS AND METHODS A total of 101 elderly patients of acute ischaemic stroke fulfilling inclusion and exclusion criteria who were admitted to M.S. Ramaiah Hospital between January 2014 and June 2016 were included in the study. Outcome was assessed by National Institute of Health Stroke Scale (NIHSS score at admission, day 5 and at discharge, duration of hospital stay and inpatient mortality. RESULTS The mean age of the patients was 67.70±8.77 years. 67.3% of the patients were males. Hypertension (72.3%, diabetes mellitus (51.5% and dyslipidaemia (48.5% were the most common co-morbid conditions. Mean NIHSS score at the time of admission was 12±5.1, on day 5 was 8.47±4.75 and at the time of discharge was 3.27±3.33. Mean duration of hospital stay was 9.01±6.45 days and mortality was seen in 4 patients (4%. Most common site for infarct was in the middle cerebral artery territory (71.71%. CONCLUSION With continuing rapid increase in life expectancy and improvement in medical care, the proportion of elderly with stroke will rise. Therefore, stroke in the elderly is rapidly becoming a major public health concern.

Stroke Repair via Biomimicry of the Subventricular Zone

Science.gov (United States)

Matta, Rita; Gonzalez, Anjelica L.

2018-03-01

Stroke is among the leading causes of death and disability worldwide, 85% of which are ischemic. Current stroke therapies are limited by a narrow effective therapeutic time and fail to effectively complete the recovery of the damaged area. Magnetic resonance imaging of the subventricular zone (SVZ) following infarct/stroke has allowed visualization of new axonal connections and projections being formed, while new immature neurons migrate from the SVZ to the peri-infarct area. Such studies suggest that the SVZ is a primary source of regenerative cells for the repair and regeneration of stroke-damaged neurons and tissue. Therefore, the development of tissue engineered scaffolds that serve as a bioreplicative SVZ niche would support the survival of multiple cell types that reside in the SVZ. Essential to replication of the human SVZ microenvironment is the establishment of microvasculature that regulates both the healthy and stroke-injured blood brain barrier, which is dysregulated post-stroke. In order to reproduce this niche, understanding how cells interact in this environment is critical, in particular neural stem cells, endothelial cells, pericytes, ependymal cells, and microglia. Remodeling and repair of the matrix-rich SVZ niche by endogenous reparative mechanisms may then support functional recovery when enhanced by an artificial niche that supports the survival and proliferation of migrating vascular and neuronal cells. Critical considerations to mimic this area include an understanding of resident cell types, delivery method, and the use of biocompatible materials. Controlling stem cell survival, differentiation, and migration are key factors to consider when transplanting stem cells. Here, we discuss the role of the SVZ architecture and resident cells in the promotion and enhancement of endogenous repair mechanisms. We elucidate the interplay between the extracellular matrix composition and cell interactions prior to and following stroke. Lastly, we review

Knowledge of stroke among stroke patients and their relatives in Northwest India.

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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.

Poststroke epilepsy in the Copenhagen stroke study: incidence and predictors

DEFF Research Database (Denmark)

Kammersgaard, Lars Peter; Olsen, Tom Skyhøj

2005-01-01

Poststroke epilepsy (PSE) is a feared complication after stroke and is reported in 3% to 5% of stroke survivors. In this study we sought to identify incidence and predictors of PSE in an unselected stroke population with a follow-up period of 7 years. The study was community-based and comprises...... a cohort of 1197 consecutively and prospectively admitted patients with stroke. Patients were followed up for 7 years. We defined PSE as recurrent epileptic seizures with onset after stroke and requiring antiepileptic prophylaxis. PSE was related to clinical factors (age, sex, onset stroke severity, lesion...... size on computed tomography scans, stroke subtype, localization, stroke risk factor profile, and early seizures) in univariate analyses. Independent predictors of PSE were identified through multiple logistic regression analyses. Overall, 38 patients (3.2%) developed PSE. Univariately, PSE...

White matter changes in stroke patients. Relationship with stroke subtype and outcome

DEFF Research Database (Denmark)

Leys, D; Englund, E; Del Ser, T

1999-01-01

or white matter lesions or leukoencephalopathy or leukoaraiosis' and 'stroke or cerebral infarct or cerebral hemorrhage or cerebrovascular disease or transient ischemic attack (TIA)'. WMC, as defined radiologically, are present in up to 44% of patients with stroke or TIA and in 50% of patients...... of death or dependency, recurrent stroke of any type, cerebral bleeding under anticoagulation, myocardial infarction, and poststroke dementia. WMC in stroke patients are often associated with small-vessel disease and lead to a higher risk of death, and poor cardiac and neurological outcome. However......White matter changes (WMC), detected by imaging techniques, are frequent in stroke patients. The aim of the study was to determine how WMC relate to stroke subtypes and to stroke outcome. We made a systematic Medline search for articles appearing with two of the following key words: either 'WMC...

Stroke care: Experiences and clinical research in stroke units in Chennai

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Gobindram Arjundas

2006-01-01

Full Text Available Background: S troke is the second commonest cause of death in India with crude overall prevalence rate of 220 per 100,000. With an increasing aging population at risk, the stroke burden in India can be expected to reach epidemic proportions. Materials and Methods: The first protocol-based prospective studies, funded by private agencies was conducted in Madras Institute of Neurology in 1984-86. The results led to establishment of the first stroke unit in Tamil Nadu state, in the institute. The first all-India hospital-based studies in acute stroke was completed as INDIAN COOPERATIVE ACUTE STROKE STUDIES (ICASS I and ICASS II with WHO STEP ONE by members of the Indian Stroke Association between 2000-2005. This has generated very useful data for our country. Results: Mortality in 1984-86 was 40%. Stroke unit in the institute dropped it to 12%. About 10 years later, ICASS studies showed a further fall of mortality to 8%, which is the current international figure in the west. Morbidity pattern showed about half return to their original activities. But about one third are left totally disabled needing prolonged care, for which fiscal, social and rehab provisions have to be done on a national basis. Conclusions: The progress and success of care of Stroke in the last three decades, from treatment in medical and neurology wards to specialized stroke units is presented. The main risk factors are hypertension, diabetes and ischemic heart disease across the country. Hypertension alone or with the other two diseases was present in 72% of cases. Prevention and treatment of these factors will reduce the stroke burden, mortality and morbidity of strokes. The Stroke-team concept can be extended to the smallest hospitals in our country.

Translating knowledge for action against stroke--using 5-minute videos for stroke survivors and caregivers to improve post-stroke outcomes: study protocol for a randomized controlled trial (Movies4Stroke).

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Kamal, Ayeesha Kamran; Khoja, Adeel; Usmani, Bushra; Muqeet, Abdul; Zaidi, Fabiha; Ahmed, Masood; Shakeel, Saadia; Soomro, Nabila; Gowani, Ambreen; Asad, Nargis; Ahmed, Asma; Sayani, Saleem; Azam, Iqbal; Saleem, Sarah

2016-01-27

Two thirds of the global mortality of stroke is borne by low and middle income countries (LMICs). Pakistan is the world's sixth most populous country with a stroke-vulnerable population and is without a single dedicated chronic care center. In order to provide evidence for a viable solution responsive to this health care gap, and leveraging the existing >70% mobile phone density, we thought it rational to test the effectiveness of a mobile phone-based video intervention of short 5-minute movies to educate and support stroke survivors and their primary caregivers. Movies4Stroke will be a randomized control, outcome assessor blinded, parallel group, single center superiority trial. Participants with an acute stroke, medically stable, with mild to moderate disability and having a stable primary caregiver will be included. After obtaining informed consent the stroke survivor-caregiver dyad will be randomized. Intervention participants will have the movie program software installed in their phone, desktop, or Android device which will allow them to receive, view and repeat 5-minute videos on stroke-related topics at admission, discharge and first and third months after enrollment. The control arm will receive standard of care at an internationally accredited center with defined protocols. The primary outcome measure is medication adherence as ascertained by a locally validated Morisky Medication Adherence Scale and control of major risk factors such as blood pressure, blood sugar and blood cholesterol at 12 months post discharge. Secondary outcome measures are post-stroke complications and mortality, caregiver knowledge and change in functional outcomes after acute stroke at 1, 3, 6, 9 and 12 months. Movies4Stroke is designed to enroll 300 participant dyads after inflating 10% to incorporate attrition and non-compliance and has been powered at 95% to detect a 15% difference between intervention and usual care arm. Analysis will be done by the intention

Numerical studies of the formation and destruction of vortices in a motored four-stroke piston-cylinder configuration

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Schock, H. J.; Sosoka, D. J.; Ramos, J. I.

1983-01-01

A finite-difference procedure which solves the conservation equations of mass, momentum, and energy is used to investigate the effects of the compression ratio, engine speed, bore-to-stroke ratio, and air intake flow angle on the turbulent flow field within an axisymmetric piston-cylinder configuration. It is shown that in a four-stroke piston-cylinder configuration, the intake stroke is characterized by the formation of a piston vortex. The piston vortex is stretched during the intake stroke, and the head vortex has an almost constant diameter. For a 0-deg air intake flow angle, both vortices disappear by the end of the compression stroke; for an air intake flow angle of 45 deg, the flow field within the cylinder shows three elongated vortices which persist into the compression stroke and then break up and merge. It is also shown that larger bore-to-stroke ratios give rise to lower turbulent levels than smaller bore-to-stroke ratios and that the turbulent intensity is almost independent of the rpm.

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

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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

Innovations in major system reconfiguration in England: a study of the effectiveness, acceptability and processes of implementation of two models of stroke care

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Fulop Naomi

2013-01-01

Full Text Available Abstract Background Significant changes in provision of clinical care within the English National Health Service (NHS have been discussed in recent years, with proposals to concentrate specialist services in fewer centres. Stroke is a major public health issue, accounting for over 10% of deaths in England and Wales, and much disability among survivors. Variations have been highlighted in stroke care, with many patients not receiving evidence-based care. To address these concerns, stroke services in London and Greater Manchester were reorganised, although different models were implemented. This study will analyse processes involved in making significant changes to stroke care services over a short time period, and the factors influencing these processes. We will examine whether the changes have delivered improvements in quality of care and patient outcomes; and, in light of this, whether the significant extra financial investment represented good value for money. Methods/design This study brings together quantitative data on ‘what works and at what cost?’ with qualitative data on ‘understanding implementation and sustainability’ to understand major system change in two large conurbations in England. Data on processes of care and their outcomes (e.g. morbidity, mortality, and cost will be analysed to evidence services’ performance before and after reconfiguration. The evaluation draws on theories related to the dissemination and sustainability of innovations and the ‘social matrix’ underlying processes of innovation. We will conduct a series of case studies based on stakeholder interviews and documentary analysis. These will identify drivers for change, how the reconfigurations were governed, developed, and implemented, and how they influenced service quality. Discussion The research faces challenges due to: the different timings of the reconfigurations; the retrospective nature of the evaluation; and the current organisational

Innovations in major system reconfiguration in England: a study of the effectiveness, acceptability and processes of implementation of two models of stroke care.

Science.gov (United States)

Fulop, Naomi; Boaden, Ruth; Hunter, Rachael; McKevitt, Christopher; Morris, Steve; Pursani, Nanik; Ramsay, Angus Ig; Rudd, Anthony G; Tyrrell, Pippa J; DA Wolfe, Charles

2013-01-05

Significant changes in provision of clinical care within the English National Health Service (NHS) have been discussed in recent years, with proposals to concentrate specialist services in fewer centres. Stroke is a major public health issue, accounting for over 10% of deaths in England and Wales, and much disability among survivors. Variations have been highlighted in stroke care, with many patients not receiving evidence-based care. To address these concerns, stroke services in London and Greater Manchester were reorganised, although different models were implemented. This study will analyse processes involved in making significant changes to stroke care services over a short time period, and the factors influencing these processes. We will examine whether the changes have delivered improvements in quality of care and patient outcomes; and, in light of this, whether the significant extra financial investment represented good value for money. This study brings together quantitative data on 'what works and at what cost?' with qualitative data on 'understanding implementation and sustainability' to understand major system change in two large conurbations in England. Data on processes of care and their outcomes (e.g. morbidity, mortality, and cost) will be analysed to evidence services' performance before and after reconfiguration. The evaluation draws on theories related to the dissemination and sustainability of innovations and the 'social matrix' underlying processes of innovation. We will conduct a series of case studies based on stakeholder interviews and documentary analysis. These will identify drivers for change, how the reconfigurations were governed, developed, and implemented, and how they influenced service quality. The research faces challenges due to: the different timings of the reconfigurations; the retrospective nature of the evaluation; and the current organisational turbulence in the English NHS. However, these issues reflect the realities of major

Burden of stroke in Bangladesh.

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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.

Patent Foramen Ovale and Cryptogenic Strokes in the Stroke in Young Fabry Patients Study.

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Huber, Roman; Grittner, Ulrike; Weidemann, Frank; Thijs, Vincent; Tanislav, Christian; Enzinger, Christian; Fazekas, Franz; Wolf, Markus; Hennerici, Michael G; McCabe, Dominick J H; Putaala, Jukaa; Tatlisumak, Turgut; Kessler, Christoph; von Sarnowski, Bettina; Martus, Peter; Kolodny, Edwin; Norrving, Bo; Rolfs, Arndt

2017-01-01

A patent foramen ovale (PFO) is disproportionately prevalent in patients with cryptogenic stroke. Without alternative explanations, it is frequently considered to be causative. A detailed stratification of these patients may improve the identification of incidental PFO. We investigated the PFO prevalence in 3497 transient ischemic attack and ischemic stroke patients aged 18 to 55 years in the prospective multicenter SIFAP1 study (Stroke in Young Fabry Patients 1) using the ASCO classification. Patients without an obvious cause for transient ischemic attack/stroke (ASCO 0) were divided into subgroups with and without vascular risk factors (ASCO 0+ and 0-). In addition, we looked for PFO-related magnetic resonance imaging lesion patterns. PFO was identified in 25% of patients. Twenty percent of patients with a definite or probable cause of transient ischemic attack/stroke (≥1 grade 1 or 2 ASCO criterion; n=1769) had a PFO compared with 29% of cryptogenic stroke patients (ASCO 0 and 3; n=1728; Pstrokes revealed a PFO in 24% of 978 ASCO 3 patients (n.s. versus ASCO 1 and 2) and a higher prevalence of 36% in 750 ASCO 0 cases (Pstroke patients demonstrate a heterogeneous PFO prevalence. Even in case of less conclusive diseases like nonstenotic arteriosclerosis, patients should preferentially be considered to have a non-PFO-mediated stroke. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00414583. © 2016 American Heart Association, Inc.

Self-perceived psychological stress and ischemic stroke: a case-control study

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Blomstrand Christian

2009-10-01

Full Text Available Abstract Background A growing body of evidence suggests that psychological stress contributes to coronary artery disease. However, associations between stress and stroke are less clear. In this study, we investigated the possible association between ischemic stroke and self-perceived psychological stress, as measured by a single-item questionnaire, previously reported to be associated with myocardial infarction. Methods In the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS, 600 consecutive patients with acute ischemic stroke (aged 18 to 69 years and 600 age-matched and sex-matched population controls were recruited. Ischemic stroke subtype was determined according to Trial of Org 10172 in Acute Stroke Treatment (TOAST criteria. Self-perceived psychological stress preceding stroke was assessed retrospectively using a single-item questionnaire. Results Permanent self-perceived psychological stress during the last year or longer was independently associated with overall ischemic stroke (multivariate adjusted odds ratio (OR 3.49, 95% confidence interval (CI 2.06 to 5.93. Analyses by stroke subtype showed that this association was present for large vessel disease (OR 3.91, 95% CI 1.58 to 9.67, small vessel disease (OR 3.20, 95% CI 1.64 to 6.24, and cryptogenic stroke (OR 4.03, 95% CI 2.34 to 6.95, but not for cardioembolic stroke (OR 1.48, 95% CI 0.64 to 3.39. Conclusion In this case-control study, we found an independent association between self-perceived psychological stress and ischemic stroke. A novel finding was that this association differed by ischemic stroke subtype. Our results emphasize the need for further prospective studies addressing the potential role for psychological stress as a risk factor for ischemic stroke. In such studies ischemic stroke subtypes should be taken into consideration.

The organisational context of nursing care in stroke units: a case study approach.

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Burton, Christopher R; Fisher, Andrea; Green, Theresa L

2009-01-01

Internationally the stroke unit is recognised as the evidence-based model for patient management, although clarity about the effective components of stroke units is lacking. Whilst skilled nursing care has been proposed as one component, the theoretical and empirical basis for stroke nursing is limited. We attempted to explore the organisational context of stroke unit nursing, to determine those features that staff perceived to be important in facilitating high quality care. A case study approach was used, that included interviews with nurses and members of the multidisciplinary teams in two Canadian acute stroke units. A total of 20 interviews were completed, transcribed and analysed thematically using the Framework Approach. Trustworthiness was established through the review of themes and their interpretation by members of the stroke units. Nine themes that comprised an organisational context that supported the delivery of high quality nursing care in acute stroke units were identified, and provide a framework for organisational development. The study highlighted the importance of an overarching service model to guide the organisation of care and the development of specialist and advanced nursing roles. Whilst multidisciplinary working appears to be a key component of stroke unit nursing, various organisational challenges to its successful implementation were highlighted. In particular the consequence of differences in the therapeutic approach of nurses and therapy staff needs to be explored in greater depth. Successful teamwork appears to depend on opportunities for the development of relationships between team members as much as the use of formal communication systems and structures. A co-ordinated approach to education and training, clinical leadership, a commitment to research, and opportunities for role and practice development also appear to be key organisational features of stroke unit nursing. Recommendations for the development of stroke nursing

Selected Issues of the Indicating Measurements in a Spark Ignition Engine with an Additional Expansion Process

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Marcin Noga

2017-03-01

Full Text Available The paper presents the results of research on the turbocharged spark ignition engine with additional exhaust expansion in a separate cylinder, which is commonly known as the five-stroke engine. The research engine has been constructed based on the four cylinder engine in which two outer cylinders work as the fired cylinders, while two internally connected inner cylinders constitute the volume of the additional expansion process. The engine represents a powertrain realizing an ultra-expansion cycle. The purpose of the study was to find an effective additional expansion process in the five-stroke engine. Cylinder-pressure indicating measurements were carried out for one of the fired cylinders and the additional expansion cylinder. The study was performed for over 20 different points on the engine operation map. This allowed us to determine a dependence between the pressure indicated in the fired cylinders and in the additional expansion cylinders. A function of the mean pressure indicated in the additional expansion cylinder versus a brake mean effective pressure was also presented. This showed a load threshold from which the work of the cylinders of additional expansion produced benefits for the output of the experimental engine. The issues of mechanical efficiency and effective efficiency of this engine were also discussed.

Life satisfaction and self-efficacy in patients affected by a first stroke living in Kuwait: a two-phase study.

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Omu, Onutobor; Reynolds, Frances

2013-08-01

Life satisfaction and self-efficacy are important aspects of stroke rehabilitation. Previous research focuses on Western stroke survivors, neglecting the stroke experience in the Middle East. This research was conducted in Kuwait and entailed both quantitative and qualitative phases to obtain a more comprehensive, clinically relevant understanding of self-efficacy and life satisfaction during stroke rehabilitation in this culture. The aims were to: 1) investigate the relationships between self-efficacy and life satisfaction in female patients affected by stroke (Phase 1); and 2) explore health professionals' views regarding the importance of self-efficacy and possible strategies for enhancing self-efficacy during rehabilitation, through semi-structured interviews (Phase 2). Significant correlations were found between patients' general self-efficacy, and psychosocial adaptation self-efficacy following stroke. Self-efficacy (both general and psychosocial adaptation) showed significant correlations with life satisfaction post-stroke. Health professionals (more than half of whom were physiotherapists) recognised the importance of self-efficacy within stroke rehabilitation and identified five main ways to increase self-efficacy during stroke rehabilitation. These were to: 1) motivate and encourage patients; 2) provide more education about stroke and rehabilitation; 3) identify change; 4) offer a high-quality environment and therapy; and 5) set goals. In conclusion, psychosocial self-efficacy was identified as having a stronger relationship to life satisfaction compared with general self-efficacy within this sample of Kuwaiti female patients. Health professionals suggested various strategies for enhancing self-efficacy and thereby life satisfaction post-stroke during the rehabilitation process in Kuwait. Despite the collectivist culture of Kuwait, the findings indicate that the patient's own confidence and sense of responsibility for progress may be relevant to

Hip Hop Stroke: Study Protocol for a Randomized Controlled Trial to Address Stroke Literacy.

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Williams, Olajide; Leighton-Herrmann, Ellyn; DeSorbo, Alexandra; Hecht, Mindy; Hedmann, Monique; Huq, Saima; Gerin, William; Chinchilli, Vernon; Ogedegbe, Gbenga; Noble, James

2015-10-01

Stroke is the fifth leading cause of death and the leading cause of serious long-term adult disability in the US. Acute stroke treatments with intravenous thrombolysis and endovascular therapy are proven to reduce disability, however a critical limitation on their effectiveness is the narrow time window for administration, which is 4.5 hours and 6 hours respectively from the onset of symptoms. Our overarching goal is to reduce pre-hospital delays to acute stroke treatments in economically disadvantaged minority communities where the greatest delays exist, using Hip Hop Stroke. Hip Hop Stroke (HHS) is a school-based, child-mediated, culturally-tailored stroke communication multimedia intervention developed using validated models of behavior change and designed to improve stroke literacy (knowledge of stroke symptoms, the urgent need to call 911, and prevention measures) of 4 th , 5 th and 6 th grade students and their parents residing in poor urban communities. Children in the intervention arm will receive the HHS intervention, while those in the attentional control arm will receive standardized nutrition education based on the USDA's MyPyramid program. Children will be trained and motivated to share stroke information with their parents or other adult caregiver. Both children and parents will complete a stroke knowledge assessment at baseline, immediately following the program, and at 3-months post-program. The primary outcome is the effect of the child mediation on parental stroke literacy. Stroke literate children, a captive audience in school systems, may represent a viable channel for spreading stroke information into households of poor urban communities where mass media stroke campaigns have shown the lowest penetration. These children may also call 911 when witnessing a stroke in their homes or communities. The HHS program may highlight the potential role of children in the chain of stroke recovery as a strategy for reducing prehospital delays to acute stroke

Pre-Stroke Weight Loss is Associated with Post-Stroke Mortality among Men in the Honolulu-Asia Aging Study

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Bell, Christina L.; Rantanen, Taina; Chen, Randi; Davis, James; Petrovitch, Helen; Ross, G. Webster; Masaki, Kamal

2013-01-01

Objective To examine baseline pre-stroke weight loss and post-stroke mortality among men. Design Longitudinal study of late-life pre-stroke body mass index (BMI), weight loss and BMI change (midlife to late-life), with up to 8-year incident stroke and mortality follow-up. Setting Honolulu Heart Program/Honolulu-Asia Aging Study. Participants 3,581 Japanese-American men aged 71–93 years and stroke-free at baseline. Main Outcome Measure Post-stroke Mortality: 30-day post-stroke, analyzed with stepwise multivariable logistic regression and long-term post-stroke (up to 8-year), analyzed with stepwise multivariable Cox regression. Results Weight loss (10-pound decrements) was associated with increased 30-day post-stroke mortality (aOR=1.48, 95%CI 1.14–1.92), long-term mortality after incident stroke (all types n=225, aHR=1.25, 95%CI=1.09–1.44) and long-term mortality after incident thromboembolic stroke (n=153, aHR 1.19, 95%CI-1.01–1.40). Men with overweight/obese late-life BMI (≥25kg/m2, compared to normal/underweight BMI) had increased long-term mortality after incident hemorrhagic stroke (n=54, aHR=2.27, 95%CI=1.07–4.82). Neither desirable nor excessive BMI reductions (vs. no change/increased BMI) were associated with post-stroke mortality. In the overall sample (n=3,581), nutrition factors associated with increased long-term mortality included 1) weight loss (10-pound decrements, aHR=1.15, 1.09–1.21); 2) underweight BMI (vs. normal BMI, aHR=1.76, 1.40–2.20); and 3) both desirable and excessive BMI reductions (vs. no change or gain, separate model from weight loss and BMI, aHRs=1.36–1.97, pstroke incidence, pre-stroke weight loss was associated with increased post-stroke (all types and thromboembolic) mortality. Overweight/obese late-life BMI was associated with increased post-hemorrhagic stroke mortality. Desirable and excessive BMI reductions were not associated with post-stroke mortality. Weight loss, underweight late-life BMI and any BMI

Characteristics of Sulfuric Acid Condensation on Cylinder Liners of Large Two-Stroke Marine Engines

DEFF Research Database (Denmark)

Cordtz, Rasmus Lage; Mayer, Stefan; Schramm, Jesper

. Formation of corrosive sulfuric acid in the cylinder gas is modeled with a cali-brated engine model that incorporates a detailed sulfur reaction mechanism. Condensation of sulfuric acid follows the analogy between heat and mass transfer. Average bulk gas acid dew points are calculated by applying two......-phase thermochemistry of the binary H2O-H2SO4 system. Max dew points of typically more than 200 °C are modeled close to max pressure and variations in terms of operating conditions are not large. However small increments of the dew point provided by e.g. the residual gas fraction, operating pressure, sulfur content...

The combined perceptions of people with stroke and their carers regarding rehabilitation needs 1 year after stroke: a mixed methods study

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Ekstam, Lisa; Johansson, Ulla; Guidetti, Susanne; Eriksson, Gunilla; Ytterberg, Charlotte

2015-01-01

Objectives The aim of the study was to explore the associations between the dyad’s (person with stroke and informal caregiver) perception of the person with stroke’s rehabilitation needs and stroke severity, personal factors (gender, age, sense of coherence), the use of rehabilitation services, amount of informal care and caregiver burden. Further, the aim was to explore the personal experience of everyday life changes among persons with stroke and their caregivers and their strategies for handling these 1 year after stroke. Design A mixed methods design was used combining quantitative and qualitative data and analyses. Setting Data were mainly collected in the participants’ homes. Outcome measures Data were collected through established instruments and open-ended interviews. The dyad's perceptions of the person with stroke’s rehabilitation needs were assessed by the persons with stroke and their informal caregivers using a questionnaire based on Ware’s taxonomy. The results were combined and classified into three groups: met, discordant (ie, not in agreement) and unmet rehabilitation needs. To assess sense of coherence (SOC) in persons with stroke, the SOC-scale was used. Caregiver burden was assessed using the Caregiver Burden Scale. Data on the use of rehabilitation services were obtained from the computerised register at the Stockholm County Council. Participants 86 persons with stroke (mean age 73 years, 38% women) and their caregivers (mean age 65 years, 40% women). Results Fifty-two per cent of the dyads perceived that the person with stroke’s need for rehabilitation was met 12 months after stroke. Met rehabilitation needs were associated with less severe stroke, more coping strategies for solving problems in everyday activities and less caregiver burden. Conclusions Rehabilitation interventions need to focus on supporting the dyads’ process of psychological and social adaptation after stroke. Future studies need to explore and evaluate

Kinesthetic taping improves walking function in patients with stroke: a pilot cohort study.

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Boeskov, Birgitte; Carver, Line Tornehøj; von Essen-Leise, Anders; Henriksen, Marius

2014-01-01

Stroke is an important cause of severe disability and impaired motor function. Treatment modalities that improve motor function in patients with stroke are needed. The objective of this study was to investigate the effect of kinesthetic taping of the anterior thigh and knee on maximal walking speed and clinical indices of spasticity in patients with stroke. Thirty-two patients (9 women) receiving rehabilitation after stroke (average, 50 days since stroke) who had impaired walking ability were recruited. Primary outcome was maximal walking speed measured by the 10-meter walk test. Secondary outcomes were number of steps taken during the test and clinical signs of spasticity measured by the Tardieu Scale. Tests were conducted before and immediately after application of kinesthetic tape to the anterior thigh and knee of the paretic lower limb. After application of the tape, the maximal walking speed increased, on average, by 0.08 m/s (95% CI, 0.04 to 0.12; P kinesthetic taping of the anterior thigh and knee provides an immediate improvement in walking function in patients with stroke. Such a positive effect on motor function could be a valuable adjunct in physical therapy and rehabilitation of patients with stroke.

Study protocol to a nationwide prospective cohort study on return to gainful occupation after stroke in Denmark 1996 - 2006

Directory of Open Access Journals (Sweden)

Humle Frank

2010-10-01

Full Text Available Abstract Background Successful return to work is regarded as one of the most important outcome factors for working-age post stroke patients. The present study will estimate the effect of various predictors on the odds of returning to work after stroke. Nearly twenty thousand 20-57 year-old stroke patients in Denmark who were gainfully occupied prior to the stroke will be included in the study. Methods/design Stroke patients will be followed prospectively through national registers. Multi-level logistic regression will be used to model the odds of being gainfully occupied ca. two years after the stroke as a function of the following predictors: Age (20-49 years, 50-57 years gender, occupational class, self-employment (yes; no, onset calendar year (1996, 1997, ..., 2006, diagnosis (subarachnoid haemorrhage; intracerebral haemorrhage; cerebral infarction; stroke, not specified as haemorrhage or infarction and 'type of municipality' (the variable is set to 1 if the person lived in a municipality which had a brain injury rehabilitation centre at the time of the stroke. Otherwise it is set to 0. Municipalities will be treated as the subjects while individual observations within municipalities are treated as correlated repeated measurements. Discussion Since our follow-up is done through registers and all people in the target population are included, the study is free from sampling bias, recall bias and non-response bias. The study is also strengthened by its size. The major weakness of the study is that it does not contain any stroke severity measures. Thus, it cannot accurately predict whether a particular stroke patient will in fact return to work. The study is, however, quite useful from a public health perspective. It can be used to estimate the proportion of patients in a certain group that is expected to return to work, and thereby provide a comparison material, which e.g. municipalities can use to evaluate their success in returning their

Medication coaching program for patients with minor stroke or TIA: A pilot study

OpenAIRE

Sides, Elizabeth G; Zimmer, Louise O; Wilson, Leslie; Pan, Wenqin; Olson, DaiWai M; Peterson, Eric D; Bushnell, Cheryl

2012-01-01

Abstract Background Patients who are hospitalized with a first or recurrent stroke often are discharged with new medications or adjustment to the doses of pre-admission medications, which can be confusing and pose safety issues if misunderstood. The purpose of this pilot study was to assess the feasibility of medication coaching via telephone after discharge in patients with stroke. Methods Two-arm pilot study of a medication coaching program with 30 patients (20 intervention, 10 control). Co...

The Fangshan/Family-based Ischemic Stroke Study In China (FISSIC protocol

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Chen Dafang

2007-09-01

Full Text Available Abstract Background The exact etiology of ischemic stroke remains unclear, because multiple genetic predispositions and environmental risk factors may be involved, and their interactions dictate the complexity. Family-based studies provide unique features in design, while they are currently underrepresented for studies of ischemic stroke in developing countries. The Fangshan/Family-based Ischemic Stroke Study In China (FISSIC program aims to conduct a genetic pedigree study of ischemic stroke in rural communities of China. Methods/Design The pedigrees of ischemic stroke with clear documentation are recruited by using the proband-initiated contact method, based on the stroke registry in hospital and communities. Blood samples and detailed information of pedigrees are collected through the health care network in the rural area, and prospective follow-up of the pedigrees cohort is scheduled. Complementary strategies of both family-based design and matched case-spousal control design are used, and comprehensive statistical methods will be implemented to ascertain potential complex genetic and environmental factors and their interactions as well. Discussion This study is complementary to other genetic pedigree studies of ischemic stroke, such as the Siblings With Ischemic Stroke Study (SWISS, which are established in developed countries. We describe the protocol of this family-based genetic epidemiological study that may be used as a new practical guideline and research paradigm in developing countries and facilitate initiatives of stroke study for international collaborations.

Stroke and nutrition: A review of studies

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Mehdi Foroughi

2013-01-01

Conclusions : Adherence to Mediterranean diet or DASH diet and increasing the consumption of antioxidant, vitamins, potassium, calcium food sources, vegetables, fruits, and whole grains intake can lower the risk of stroke. Healthy diet is effective in reducing risk of stroke, however, more studies need to be carried out in this area.

Association between acute statin therapy, survival, and improved functional outcome after ischemic stroke: the North Dublin Population Stroke Study.

LENUS (Irish Health Repository)

2011-04-01

Statins improve infarct volume and neurological outcome in animal stroke models. We investigated the relationship between statin therapy and ischemic stroke outcome in the North Dublin Population Stroke Study.

Changes in the management of acute ischemic stroke after publication of Japanese Guidelines for the Management of Stroke (2004). A multicenter cooperative study in Toyama prefecture

International Nuclear Information System (INIS)

Takashima, Shutaro; Toyoda, Shigeo; Tanaka, Kortaro

2009-01-01

It is unclear whether the management of stroke has been improved since the Japanese Guidelines for the Management of Stroke (2004) was published. The aim of the present study was to clarify changes in the management for acute ischemic stroke after publication of the Japanese Guidelines. We investigated the management of patients with acute ischemic stroke in nine hospitals belonging to the committee of Toyama Acute Ischemic Stroke Study, before and after publication of the Japanese Guidelines for the Management of Stroke (2004). Two-hundred and ninety-three acute ischemic stroke patients were registered in 2003 and 237 in 2006, respectively. The percentage of lacunar stroke was 39%, 37%, atherothrombotic infarction; 28%, 30%, cardioembolic stroke (CE); 21%, 22%, and others; 12%, 11%, respectively. The ratio of CE patients who were admitted within 3 hours of onset was significantly increased from 34% in 2003 to 57% in 2006. Although 74 patients (31%) with any clinical type were admitted within 3 hours of onset, thrombolytic therapy with tissue plasminogen activator (rt-PA) was administered to only 5 patients (2.1%) in 2006. Diffusion weighted images became available in all hospitals, and were more frequently used for diagnosis of acute ischemic stroke in 92% of patients in 2006 as compared to 59% in 2003. Ischemic lesions were more frequently detected before the start of treatment in 52% of patients in 2006 as compared to 43% in 2003. After the Japanese Guidelines for the Management of Stroke (2004) was published, the treatment of acute ischemic stroke patients appeared to follow this guideline in many patients. Thrombolytic therapy with rt-PA, however, was performed in very few patients. (author)

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

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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.

Comparison of two imaging protocols for acute stroke: unenhanced cranial CT versus a multimodality cranial CT protocol with perfusion imaging

International Nuclear Information System (INIS)

Langer, R. D.; Gorkom, K. Neidl van.; Kaabi, Ho Al.; Torab, F.; Czechowski, J.; Nagi, M.; Ashish, G. M.

2007-01-01

Full text: The aim of the study was to validate a multimodality cranial computed tomography (CCT) protocol for patients with acute stroke in the United Arab Emirates as a basic imaging procedure for a stroke unit. Therefore, a comparative study was conducted between two groups: retrospective, historical group 1 with early unenhanced CCT and prospective group 2 undergoing a multimodality CCT protocol. Follow-up unenhanced CCT >48 h served as gold standard in both groups. Group 1: Early unenhanced CCT of 50 patients were evaluated retrospectively, using Alberta Stroke Program Early CT Score, and compared with the definite infarction on follow-up CCT. Group 2: 50 patients underwent multimodality CCT (unenhanced CCT, perfusion studies: cerebral blood flow, cerebral blood volume, mean transit time and CT angiography) <8 h after clinical onset and follow-up studies. Modified National Institute of Health Stroke Scale was used clinically in both groups. Group 1 showed 38 men, 12 women, clinical onset 2-8 h before CCT and modified National Institute of Health Stroke Scale 0-28. Group 2 included 38 men, 12 women, onset 3-8 h before CCT, modified National Institute of Health Stroke Scale 0-28. Sensitivity was 58.3% in group 1 and 84.2% in group 2. Computed tomography angiography detected nine intracranial occlusions/stenoses. The higher sensitivity of the multimodality CCT protocol justifies its use as a basic diagnostic tool for the set-up of a first-stroke unit in the United Arab Emirates

Post-stroke disposition from a geriatric-rehabilitative stroke care area: an Italian experience

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Marco Masina

2014-02-01

Full Text Available A large number of stroke patients cannot be discharged at home. Studies on post stroke disposition have low validity outside the country in which they are carried out because healthcare systems offer different rehabilitative and long-term facilities. Moreover absolute selection criteria for admission to rehabilitation are not available yet. Few studies on post-stroke disposition from Italian stroke units are available. Authors evaluated data of a 18-month period from a geriatric managed stroke care area where comprehensive multi-professional assessment and discharge planning are routinely carried out. Only patients discharged with diagnosis related to acute stroke were considered. Baseline characteristics, clinical, neurological and functional conditions according to the structured multidimensional assessment were prospectively collected in the stroke unit registry. Univariate and multinomial logistic regression were performed to identify independent variables associated with three discharge settings: home, rehabilitation and skilled long-term ward. Out of 188 patients evaluated, 56.4% were discharged home, 18.6% to rehabilitation and 25.0% to long-term ward. Data showed an efficient disposition to intermediate settings with a shorter length of stay compared to other international studies. Factors associated with post-stroke disposition were age, dysphagia, neurological impairment on admission (NIH-SS≥6, after stroke functional status (mRankin≥3, poor pre-stroke functional level (mRankin≥3 and hemorrhagic stroke. Dysphagia, severe neurological impairment and post-stroke disability were associated with discharge to rehabilitation and long term ward. These two settings differed in age and pre-stroke functional condition. Patients discharged to long-term wards were about 10 years older than those admitted to rehabilitative ward. Only 5% of patients discharged to rehabilitation had a pre-stroke mRankin score ≥3. Disposition to a skilled

Stroke Repair via Biomimicry of the Subventricular Zone

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Rita Matta

2018-03-01

Full Text Available Stroke is among the leading causes of death and disability worldwide, 85% of which are ischemic. Current stroke therapies are limited by a narrow effective therapeutic time and fail to effectively complete the recovery of the damaged area. Magnetic resonance imaging of the subventricular zone (SVZ following infarct/stroke has allowed visualization of new axonal connections and projections being formed, while new immature neurons migrate from the SVZ to the peri-infarct area. Such studies suggest that the SVZ is a primary source of regenerative cells for the repair and regeneration of stroke-damaged neurons and tissue. Therefore, the development of tissue engineered scaffolds that serve as a bioreplicative SVZ niche would support the survival of multiple cell types that reside in the SVZ. Essential to replication of the human SVZ microenvironment is the establishment of microvasculature that regulates both the healthy and stroke-injured blood–brain barrier, which is dysregulated poststroke. In order to reproduce this niche, understanding how cells interact in this environment is critical, in particular neural stem cells, endothelial cells, pericytes, ependymal cells, and microglia. Remodeling and repair of the matrix-rich SVZ niche by endogenous reparative mechanisms may then support functional recovery when enhanced by an artificial niche that supports the survival and proliferation of migrating vascular and neuronal cells. Critical considerations to mimic this area include an understanding of resident cell types, delivery method, and the use of biocompatible materials. Controlling stem cell survival, differentiation, and migration are key factors to consider when transplanting stem cells. Here, we discuss the role of the SVZ architecture and resident cells in the promotion and enhancement of endogenous repair mechanisms. We elucidate the interplay between the extracellular matrix composition and cell interactions prior to and following stroke

Acute post-stroke blood pressure relative to premorbid levels in intracerebral haemorrhage versus major ischaemic stroke: a population-based study

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Fischer, Urs; Cooney, Marie Therese; Bull, Linda M; Silver, Louise E; Chalmers, John; Anderson, Craig S; Mehta, Ziyah; Rothwell, Peter M

2014-01-01

Summary Background It is often assumed that blood pressure increases acutely after major stroke, resulting in so-called post-stroke hypertension. In view of evidence that the risks and benefits of blood pressure-lowering treatment in acute stroke might differ between patients with major ischaemic stroke and those with primary intracerebral haemorrhage, we compared acute-phase and premorbid blood pressure levels in these two disorders. Methods In a population-based study in Oxfordshire, UK, we recruited all patients presenting with stroke between April 1, 2002, and March 31, 2012. We compared all acute-phase post-event blood pressure readings with premorbid readings from 10-year primary care records in all patients with acute major ischaemic stroke (National Institutes of Health Stroke Scale >3) versus those with acute intracerebral haemorrhage. Findings Of 653 consecutive eligible patients, premorbid and acute-phase blood pressure readings were available for 636 (97%) individuals. Premorbid blood pressure (total readings 13 244) had been measured on a median of 17 separate occasions per patient (IQR 8–31). In patients with ischaemic stroke, the first acute-phase systolic blood pressure was much lower than after intracerebral haemorrhage (158·5 mm Hg [SD 30·1] vs 189·8 mm Hg [38·5], pblood pressure after intracerebral haemorrhage was substantially higher than premorbid levels (mean increase of 40·7 mm Hg, pblood pressure also increased steeply in the days and weeks before intracerebral haemorrhage (regression pblood pressure reading after primary intracerebral haemorrhage was more likely than after ischaemic stroke to be the highest ever recorded (OR 3·4, 95% CI 2·3–5·2, pblood pressure within 3 h of onset was 50 mm Hg higher, on average, than the maximum premorbid level whereas that after ischaemic stroke was 5·2 mm Hg lower (pblood pressure is substantially raised compared with usual premorbid levels after intracerebral haemorrhage, whereas acute

Prediabetes is associated with post-stroke cognitive impairment in ischaemic stroke patients.

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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.

Hyponatremia in stroke

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Sheikh Saleem

2014-01-01

Full Text Available Introduction: Hyponatremia is a common electrolyte disorder encountered in patients of neurological disorders which is usually either due to inappropriate secretion of Antidiuretic hormone (SIADH or cerebral salt wasting syndrome (CSWS. We conducted this study in a tertiary care hospital to determine the incidence and etiology of hyponatremia in patients of stroke admitted in the hospital. Materials and Methods: It was a prospective study done over a period of two years that included established cases of stroke diagnosed on the basis of clinical history, examination and neuroimaging. 1000 stoke patients were evaluated for hyponatremia (serum sodium <130 meq/l. The data was analysed using Chi-square test using SPSS (Statistical package for social science software. Results: Out of 1000 patients, 353 patients had hyponatremia. Out of this 353 patients, 238 (67% had SIADH and 115 (33% had CSWS. SIADH was seen in 83 patients who had ischemic stroke and 155 patients of hemorrhagic stroke. CSWS was found in 38 patients with ischemic stroke and 77 patients with hemorrhagic stroke. Statistical analysis revealed that hyponatremia significantly affects the outcome of stroke especially when it is due to CSWS rather than SIADH. Conclusion: Incidence of hyponatremia in our study population was 35%. In patients of hyponatremia 67% were having SIADH and 33% were having CSWS. Overall hyponatremia affected the outcome of stroke especially when caused by CSWS. Therefore close monitoring of serum sodium must be done in all patients who are admitted with stroke and efforts must be made to determine the cause of hyponatremia, in order to properly manage such patients thereby decreasing the mortality rate.

ABO Blood Type and Stroke Risk: The REasons for Geographic and Racial Differences in Stroke (REGARDS) Study

Science.gov (United States)

Zakai, Neil A.; Judd, Suzanne E.; Alexander, Kristine; McClure, Leslie A.; Kissela, Brett M.; Howard, George; Cushman, Mary

2016-01-01

Background ABO blood type is an inherited trait associated with coagulation factor levels and vascular outcomes. Objectives To assess the association of blood type with stroke and whether blood type contributes to racial disparities in stroke in the United States. Patients and Methods The REasons for Geographic and Racial Differences in Stroke (REGARDS) Study recruited 30,239 participants between 2003-07. Using a case-cohort design, blood type was genotyped in 646 participants with stroke and a 1,104 participant cohort random sample. Cox models adjusting for Framingham stroke risk factors assessed the association of blood type with stroke. Results Over 5.8 years of follow-up, blood types A or B versus type O were not associated with stroke. Blood type AB versus O was associated with an increased risk of stroke (adjusted HR 1.83; 95% CI 1.01, 3.30). The association of blood type AB versus O was greater in those without diabetes (adjusted HR 3.33; 95% CI 1.61, 6.88) than those with diabetes (adjusted HR 0.49; 95% CI 0.17, 1.44) (p-interaction = 0.02). Factor VIII levels accounted for 60% (95% CI 11%, 98%) of the association of AB blood type and stroke risk. Conclusion Blood type AB is associated with an increased risk of stroke that is not attenuated by conventional stroke risk factors and factor VIII levels were associated with 60% of the association. While blood type AB is rare in the U.S. population, it is a significant stroke risk factor and may play an important role in stroke risk in these individuals. PMID:24444093

Development and Experimental Investigation of a Two-Stroke Opposed-Piston Free-Piston Engine

OpenAIRE

Schneider, Stephan; Chiodi, Marco; Friedrich, Horst E.; Bargende, Michael

2016-01-01

The proposed paper deals with the development process and initial measurement results of an opposed-piston combustion engine for application in a Free-Piston Linear Generator (FPLG). The FPLG, which is being developed at the German Aerospace Center (DLR), is an innovative internal combustion engine for a fuel based electrical power supply. With its arrangement, the pistons freely oscillate between the compression chamber of the combustion unit and a gas spring with no mechanical coupling like...

Endothelial dysfunction, vascular disease and stroke: the ARTICO study.

Science.gov (United States)

Roquer, J; Segura, T; Serena, J; Castillo, J

2009-01-01

Endothelial dysfunction is a fundamental step in the atherosclerotic disease process. Its presence is a risk factor for the development of clinical events, and may represent a marker of atherothrombotic burden. Also, endothelial dysfunction contributes to enhanced plaque vulnerability, may trigger plaque rupture, and favors thrombus formation. The assessment of endothelial vasomotion is a useful marker of atherosclerotic vascular disease. There are different methods to assess endothelial function: endothelium-dependent vasodilatation brachial flow-mediated dilation, cerebrovascular reactivity to L-arginine, and the determination of some biomarkers such as microalbuminuria, platelet function, and C-reactive protein. Endothelial dysfunction has been observed in stroke patients and has been related to stroke physiopathology, stroke subtypes, clinical severity and outcome. Resting ankle-brachial index (ABI) is also considered an indicator of generalized atherosclerosis, and a low ABI is associated with an increase in stroke incidence in the elderly. Despite all these data, there are no studies analyzing the predictive value of ABI for new cardiovascular events in patients after suffering an acute ischemic stroke. ARTICO is an ongoing prospective, observational, multicenter study being performed in 50 Spanish hospitals. The aim of the ARTICO study is to evaluate the prognostic value of a pathological ABI (ARTICO study will increase the knowledge of patient outcome after ischemic stroke and may help to improve our ability to detect patients at high risk of stroke recurrence or major cardiovascular events. (c) 2009 S. Karger AG, Basel.

Lower Risk of Stroke after Deformity Surgery: Long Term Benefit Demonstrated by a National Cohort Study

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Liang-Chung Huang

2015-10-01

Full Text Available Objectives: This study aimed to investigate the long-term risk of stroke in adult patients with spinal deformity. Specifically, the study addressed the possible protective effect of surgery for spinal deformity against stroke. Methods: Using the National Health Insurance Research Database (NHIRD, a monopolistic national database in Taiwan, this retrospective cohort study analyzed the incidence of stroke in patients with adult spinal deformity (ASD in a 11-year period. A total of 13,503 patients, between 55 and 75 years old, were identified for the diagnosis of ASD. The patients were grouped into two: the surgical group (n = 10,439 who received spinal fusion surgery, and the control group (n = 2124 who received other medical treatment. The incidence rates of all subsequent cerebrovascular accidents, including ischemic and hemorrhagic strokes, were calculated. Hazard ratios for stroke were calculated use a full cohort and a propensity score matched cohort. Adjustments for co-morbidities that may predispose to stroke, including hypertension, diabetes mellitus, arrhythmia and coronary heart disease were conducted. Kaplan-Meier and Cox regression analyses were performed to compare the risk of stroke between the two groups. Results: During the total observation period of 50,450 person-years, the incidence rate of stroke in the surgical group (15.55 per 1000 person-years was significantly lower than that of the control group (20.89 per 1000 person-years, p < 0.001. Stroke was more likely to occur in the control group than in the surgical group (crude hazard ratio 1.34, p < 0.001; adjusted HR 1.28, p < 0.001, by a propensity score matched model. Conclusions: In this national cohort of more than 13,000 ASD patients covering 10 years, stroke was approximately 25% less likely to happen in patients who underwent spinal fusion surgery than those who received medical management. Therefore, spinal fusion surgery may provide a protective effect against stroke

Stroke code improves intravenous thrombolysis administration in acute ischemic stroke.

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Chih-Hao Chen

Full Text Available Timely intravenous (IV thrombolysis for acute ischemic stroke is associated with better clinical outcomes. Acute stroke care implemented with "Stroke Code" (SC may increase IV tissue plasminogen activator (tPA administration. The present study aimed to investigate the impact of SC on thrombolysis.The study period was divided into the "pre-SC era" (January 2006 to July 2010 and "SC era" (August 2010 to July 2013. Demographics, critical times (stroke symptom onset, presentation to the emergency department, neuroimaging, thrombolysis, stroke severity, and clinical outcomes were recorded and compared between the two eras.During the study period, 5957 patients with acute ischemic stroke were admitted; of these, 1301 (21.8% arrived at the emergency department within 3 h of stroke onset and 307 (5.2% received IV-tPA. The number and frequency of IV-tPA treatments for patients with an onset-to-door time of <3 h increased from the pre-SC era (n = 91, 13.9% to the SC era (n = 216, 33.3% (P<0.001. SC also improved the efficiency of IV-tPA administration; the median door-to-needle time decreased (88 to 51 min, P<0.001 and the percentage of door-to-needle times ≤60 min increased (14.3% to 71.3%, P<0.001. The SC era group tended to have more patients with good outcome (modified Rankin Scale ≤2 at discharge (49.5 vs. 39.6%, P = 0.11, with no difference in symptomatic hemorrhage events or in-hospital mortality.The SC protocol increases the percentage of acute ischemic stroke patients receiving IV-tPA and decreases door-to-needle time.

Increased work and social engagement is associated with increased stroke specific quality of life in stroke survivors at 3 months and 12 months post-stroke: a longitudinal study of an Australian stroke cohort.

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Tse, Tamara; Binte Yusoff, Siti Zubaidah; Churilov, Leonid; Ma, Henry; Davis, Stephen; Donnan, Geoffrey Alan; Carey, Leeanne M

2017-09-01

There is a relative lack of longitudinal studies investigating stroke-specific outcomes and quality of life (QOL). This study aimed to identify which factors (level of disability, cognitive functioning, depressive symptoms, physical activity, and work and social engagement) were independently associated with each stroke-specific domain of QOL, adjusting for age and gender, at 3 months and 12 months post-stroke in an Australian cohort. Survivors of ischemic stroke were recruited from 18 sites of the STroke imAging pRevention and Treatment (START) longitudinal cohort study. Survivors were assessed at 3 months (n = 185) and 12 months (n = 170) post-stroke using the Stroke Impact Scale (SIS), modified Rankin Scale (mRS), Montreal Cognitive Assessment (MoCA), Montgomery-Asberg Depression Rating Scale, Rapid Assessment of Physical Activity, and Work and Social Adjustment Scale (WSAS). WSAS was independently associated with the SIS domains of: Physical Composite function; Participation; and Perceived Recovery at 3 months and 12 months and SIS domain of Emotion at 12 months post-stroke. The presence of depressive symptoms was independently associated with the SIS domains of: Memory and Thinking; and Emotion at 3 months. At 12 months post-stroke, mRS was independently associated with SIS domain of Physical Composite function and MoCA with SIS domain of Communication. Engaging in work and social activities is an important factor associated with stroke-specific domains of QOL over time. It is recommended that services focus on improving work and social engagement given their importance related to QOL in the first year of recovery post-stroke. Identifying and treating those with depressive symptoms may enhance QOL in the early months post-stroke. START-PrePARE Australian New Zealand Clinical Trials, www.anzctr.org.au , Registry number: ACTRN12610000987066. EXTEND ClinicalTrial.gov identifier: NCT00887328.

"EMMA Study: a Brazilian community-based cohort study of stroke mortality and morbidity".

Science.gov (United States)

Goulart, Alessandra Carvalho

2016-01-01

Stroke has a high burden of disability and mortality. The aim here was to evaluate epidemiology, risk factors and prognosis for stroke in the EMMA Study (Study of Stroke Mortality and Morbidity). Prospective community-based cohort carried out in Hospital Universitário, University of São Paulo, 2006-2014. Stroke data based on fatal and non-fatal events were assessed, including sociodemographic data, mortality and predictors, which were evaluated by means of logistic regression and survival analyses. Stroke subtype was better defined in the hospital setting than in the local community. In the hospital phase, around 70% were first events and the ischemic subtype. Among cerebrovascular risk factors, the frequency of alcohol intake was higher in hemorrhagic stroke (HS) than in ischemic stroke (IS) cases (35.4% versus 12.3%, P hemorrhagic stroke was greater than for ischemic stroke and reached its maximum 10 days after the event (OR: 3.31; 95% CI: 1.55-7.05). Four-year survival analysis on 665 cases of first stroke (82.6% ischemic and 17.4% hemorrhagic) showed an overall survival rate of 48%. At four years, the highest risks of death were in relation to ischemic stroke and illiteracy (hazard ratio, HR: 1.83; 95% CI: 1.26-2.68) and diabetes (HR: 1.45; 95% CI: 1.07-1.97). Major depression presented worse one-year survival (HR: 4.60; 95% CI: 1.36-15.55). Over the long term, the EMMA database will provide additional information for planning resources destined for the public healthcare system.

Suicide after a stroke: a population study

DEFF Research Database (Denmark)

Teasdale, T W; Engberg, A W

2001-01-01

STUDY OBJECTIVE: To establish whether there are increased rates of suicide after a stroke and the degree to which any increase is related to gender, age at stroke, diagnosis, duration of hospitalisation, and time since stroke. DESIGN: Cross linkage of national registers for hospitalisations...... cases of suicide were identified. MAIN RESULTS: Annual incidence rates, both observed and expected, together with standardised mortality ratios (SMR) were computed based on annual population and suicide statistics, stratified by age and gender. The overall annual incidence rate of suicide in the cohort.......76) for patients under 50 years of age group and were least for patients 80 years or older (1.3; 0.95, 1.79). There was no clear relation to stroke diagnosis. Suicides were negatively related to duration of hospitalisation, being lowest for those hospitalised for more than three months (0.88; 0.65, 1...

How are household economic circumstances affected after a stroke? The Psychosocial Outcomes In StrokE (POISE) Study.

Science.gov (United States)

Essue, Beverley M; Hackett, Maree L; Li, Qiang; Glozier, Nick; Lindley, Richard; Jan, Stephen

2012-11-01

Stroke is associated with severe economic consequences. This is the first study to investigate in younger survivors the household economic burden of stroke. A multicenter, 3-year prospective cohort study was conducted of younger (18-65 years) survivors in Australia. Pre- and poststroke patterns of income and hardship were evaluated and multivariable logistic regression identified the predictors of economic hardship after stroke. Four hundred fourteen participants were followed up over 12 months after stroke. The variables that independently predicted economic hardship after stroke were: female (OR, 2.94; 95% CI, 1.52-5.70), hazardous alcohol consumption (OR, 2.28; 95% CI, 1.00-5.20), manual occupation (OR, 1.88; 95% CI, 1.07-3.30), lack of health insurance (OR, 2.01; 95% CI, 1.12-3.60), and prior hardship (OR, 3.93; 95% CI, 2.12-7.29), whereas concessional status (OR, 0.50; 95% CI, 0.26-0.95) and more social contacts per week (OR, 0.99; 95% CI, 0.98-1.00) reduced hardship likelihood. Higher prestroke income did not buffer hardship after stroke nor did clinical, health service, or disability factors. Policies to reduce inequalities after stroke would be best aimed at socioeconomic targets.

Antipsychotic medications and stroke in schizophrenia: A case-crossover study.

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Wen-Yin Chen

Full Text Available The association between antipsychotic use and the risk of stroke in schizophrenic patients is controversial. We sought to study the association in a nationwide cohort with schizophrenia.Using a retrospective cohort of patients with schizophrenia (N = 31,976 derived from the Taiwan National Health Insurance Research Database, 802 new-onset cases of stroke were identified within 10 years of follow-up (from 2000 through 2010. We designed a case-crossover study using 14-day windows to explore the risk factors of stroke and the association between antipsychotic drugs and the risk of stroke. We analyzed the risks of individual antipsychotics on various subgroups of stroke including ischemic, hemorrhagic, and other strokes, and the risks based on the antipsychotic receptor-binding profile of each drug.Use of any second-generation antipsychotic was associated with an increased risk of stroke (adjusted risk ratio = 1.45, P = .009 within 14 days while the use of any first-generation antipsychotic was not. Intriguingly, the use of any second-generation antipsychotic was associated with ischemic stroke but not hemorrhagic stroke. The antipsychotic receptor-binding profile analysis showed that the antihistamine 1 receptor was significantly associated with ischemic stroke (adjusted risk ratio = 1.72, P = .037, and the sensitivity analysis based on the 7-day window of exposure validated the association (adjusted risk ratio = 1.87, P = .015.Use of second-generation antipsychotic drugs appeared to be associated with an increased risk of ischemic stroke in the patients studied, possibly mediated by high affinity for histamine-1 receptor blockade. Further research regarding the underlying biological mechanism and drug safety is suggested.

Ischemic stroke risk, smoking, and the genetics of inflammation in a biracial population: the stroke prevention in young women study

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Sorkin John D

2008-08-01

Full Text Available Abstract Background Although cigarette smoking is a well-established risk factor for vascular disease, the genetic mechanisms that link cigarette smoking to an increased incidence of stroke are not well understood. Genetic variations within the genes of the inflammatory pathways are thought to partially mediate this risk. Here we evaluate the association of several inflammatory gene single nucleotide polymorphisms (SNPs with ischemic stroke risk among young women, further stratified by current cigarette smoking status. Methods A population-based case-control study of stroke among women aged 15–49 identified 224 cases of first ischemic stroke (47.3% African-American and 211 age-comparable control subjects (43.1% African-American. Several inflammatory candidate gene SNPs chosen through literature review were genotyped in the study population and assessed for association with stroke and interaction with smoking status. Results Of the 8 SNPs (across 6 genes analyzed, only IL6 SNP rs2069832 (allele C, African-American frequency = 92%, Caucasian frequency = 55% was found to be significantly associated with stroke using an additive model, and this was only among African-Americans (age-adjusted: OR = 2.2, 95% CI = 1.0–5.0, p = 0.049; risk factor adjusted: OR = 2.5, 95% CI = 1.0–6.5, p = 0.05. When stratified by smoking status, two SNPs demonstrated statistically significant gene-environment interactions. First, the T allele (frequency = 5% of IL6 SNP rs2069830 was found to be protective among non-smokers (OR = 0.30, 95% CI = 0.11–.082, p = 0.02, but not among smokers (OR = 1.63, 95% CI = 0.48–5.58, p = 0.43; genotype by smoking interaction (p = 0.036. Second, the C allele (frequency = 39% of CD14 SNP rs2569190 was found to increase risk among smokers (OR = 2.05, 95% CI = 1.09–3.86, p = 0.03, but not among non-smokers (OR = 0.93, 95% CI = 0.62–1.39, p = 0.72; genotype by smoking interaction (p = 0.039. Conclusion This study demonstrates

Effects of Specific Fuel Consumption and Exhaust Emissions of Four Stroke Diesel Engine with CuO/Water Nanofluid as Coolant

Directory of Open Access Journals (Sweden)

Senthilraja S.

2017-03-01

Full Text Available This article reports the effects of CuO/water based coolant on specific fuel consumption and exhaust emissions of four stroke single cylinder diesel engine. The CuO nanoparticles of 27 nm were used to prepare the nanofluid-based engine coolant. Three different volume concentrations (i.e 0.05%, 0.1%, and 0.2% of CuO/water nanofluids were prepared by using two-step method. The purpose of this study is to investigate the exhaust emissions (NOx, exhaust gas temperature and specific fuel consumption under different load conditions with CuO/water nanofluid. After a series of experiments, it was observed that the CuO/water nanofluids, even at low volume concentrations, have a significant influence on exhaust emissions. The experimental results revealed that, at full load condition, the specific fuel consumption was reduced by 8.6%, 15.1% and 21.1% for the addition of 0.05%, 0.1% and 0.2% CuO nanoparticles with water, respectively. Also, the emission tests were concluded that 881 ppm, 853 ppm and 833 ppm of NOx emissions were observed at high load with 0.05%, 0.1% and 0.2% volume concentrations of CuO/water nanofluids, respectively.

Comprehensive Small Engine Repair.

Science.gov (United States)

Hires, Bill; And Others

This curriculum guide contains the basic information needed to repair all two- and four-stroke cycle engines. The curriculum covers four areas, each consisting of one or more units of instruction that include performance objectives, suggested activities for teacher and students, information sheets, assignment sheets, job sheets, visual aids,…

Effects of Centralizing Acute Stroke Services on Stroke Care Provision in Two Large Metropolitan Areas in England

Science.gov (United States)

Morris, Stephen; Hoffman, Alex; Hunter, Rachael M.; Boaden, Ruth; McKevitt, Christopher; Perry, Catherine; Pursani, Nanik; Rudd, Anthony G.; Turner, Simon J.; Tyrrell, Pippa J.; Wolfe, Charles D.A.; Fulop, Naomi J.

2015-01-01

Background and Purpose— In 2010, Greater Manchester and London centralized acute stroke care into hyperacute units (Greater Manchester=3, London=8), with additional units providing ongoing specialist stroke care nearer patients’ homes. Greater Manchester patients presenting within 4 hours of symptom onset were eligible for hyperacute unit admission; all London patients were eligible. Research indicates that postcentralization, only London’s stroke mortality fell significantly more than elsewhere in England. This article attempts to explain this difference by analyzing how centralization affects provision of evidence-based clinical interventions. Methods— Controlled before and after analysis was conducted, using national audit data covering Greater Manchester, London, and a noncentralized urban comparator (38 623 adult stroke patients, April 2008 to December 2012). Likelihood of receiving all interventions measured reliably in pre- and postcentralization audits (brain scan; stroke unit admission; receiving antiplatelet; physiotherapist, nutrition, and swallow assessments) was calculated, adjusting for age, sex, stroke-type, consciousness, and whether stroke occurred in-hospital. Results— Postcentralization, likelihood of receiving interventions increased in all areas. London patients were overall significantly more likely to receive interventions, for example, brain scan within 3 hours: Greater Manchester=65.2% (95% confidence interval=64.3–66.2); London=72.1% (71.4–72.8); comparator=55.5% (54.8–56.3). Hyperacute units were significantly more likely to provide interventions, but fewer Greater Manchester patients were admitted to these (Greater Manchester=39%; London=93%). Differences resulted from contrasting hyperacute unit referral criteria and how reliably they were followed. Conclusions— Centralized systems admitting all stroke patients to hyperacute units, as in London, are significantly more likely to provide evidence-based clinical

Development and application of laser techniques for studying fuel dynamics and NO formation in engines

Energy Technology Data Exchange (ETDEWEB)

Andersson, Oeivind

2000-11-01

In this work a number of laser techniques have been applied in new ways for combustion diagnostics in engines. The applications cover small two-stroke engines, ordinary spark ignition (SI) engines, direct-injection spark ignition (DISI) engines, and heavy-duty diesel truck engines. In an investigation of unmodified two-stroke engines running at high engine speed, it has been shown that cycle-resolved laser diagnostics are applicable to real-world engines. The emission of unburned fuel was detected at the exhaust port with successful discrimination against other unburned hydrocarbons. Although a few problems remain to be solved in order to get quantitative concentration data, valuable information can nonetheless be attained using this technique. The technique would benefit from the use of a non-fluorescing lubricant, as that would decrease the background fluorescence. Laser-based techniques also provide a useful tool for studying the fuel dynamics inside the cylinder. In the development of DISI engines it is of particular importance to acquire knowledge about the distribution of fuel around the spark plug. Numerical computer codes are often used as design tools in these applications. Laser techniques are capable of yielding instantaneous multi-point concentration information with high spatial and temporal resolution, making them ideal both for validation of CFD simulations and for testing designs. The feasibility of using laser diagnostics in the development of DISI engines has been shown. Future research should be aimed at simplifying the procedure for quantifying the data, since a fairly simple and reliable technique would be an important asset for the industry. In a more fundamental study, it has been shown that it is possible to simultaneously detect a substance in both liquid and vapour phase. Water was used in the study since it is easily produced in both phases. Liquid drops were detected using spontaneous Raman scattering, whereas the vapour surrounding them

Development and application of laser techniques for studying fuel dynamics and NO formation in engines

Energy Technology Data Exchange (ETDEWEB)

Andersson, Oeivind

2000-11-01

In this work a number of laser techniques have been applied in new ways for combustion diagnostics in engines. The applications cover small two-stroke engines, ordinary spark ignition (SI) engines, direct-injection spark ignition (DISI) engines, and heavy-duty diesel truck engines. In an investigation of unmodified two-stroke engines running at high engine speed, it has been shown that cycle-resolved laser diagnostics are applicable to real-world engines. The emission of unburned fuel was detected at the exhaust port with successful discrimination against other unburned hydrocarbons. Although a few problems remain to be solved in order to get quantitative concentration data, valuable information can nonetheless be attained using this technique. The technique would benefit from the use of a non-fluorescing lubricant, as that would decrease the background fluorescence. Laser-based techniques also provide a useful tool for studying the fuel dynamics inside the cylinder. In the development of DISI engines it is of particular importance to acquire knowledge about the distribution of fuel around the spark plug. Numerical computer codes are often used as design tools in these applications. Laser techniques are capable of yielding instantaneous multi-point concentration information with high spatial and temporal resolution, making them ideal both for validation of CFD simulations and for testing designs. The feasibility of using laser diagnostics in the development of DISI engines has been shown. Future research should be aimed at simplifying the procedure for quantifying the data, since a fairly simple and reliable technique would be an important asset for the industry. In a more fundamental study, it has been shown that it is possible to simultaneously detect a substance in both liquid and vapour phase. Water was used in the study since it is easily produced in both phases. Liquid drops were detected using spontaneous Raman scattering, whereas the vapour surrounding them

The role of genetics in stroke risk factors; the discussion of two rare genetic syndroms associated with stroke and review of the literature

Directory of Open Access Journals (Sweden)

Eda Kılıç Çoban

2015-09-01

Full Text Available Stroke is defined as a focal or at times global neurological impairment of sudden onset, that lasts more than 24 hours or that leads to death. The nonmodifiable risk factors for stroke include age, race, gender and acquired risk factors include smoking, hypertension, diabetes and obesity. Previous studies have shown that these mentioned risk factors might be responsible for approximately 50% of patients presenting stroke. However for the remaining half of the stroke patients no risk factors could be detected and genetics might be responsible for this group. In this manuscript we would like to present 2 cases who were being followed-up with the rare genetic syndromes as Marfan syndrome and Robinow syndrome respectively. These patients presented to our clinic with stroke and no identifiable risk factors other than these genetic syndromes could be detected. By this case-series we would like to further discuss the relationship between genetic syndromes and stroke.

Association between seizures after ischemic stroke and stroke outcome

OpenAIRE

Xu, Tao; Ou, Shu; Liu, Xi; Yu, Xinyuan; Yuan, Jinxian; Huang, Hao; Chen, Yangmei

2016-01-01

Abstract A systematic review and meta-analysis were performed to investigate a potential association between post-ischemic stroke seizures (PISS) and subsequent ischemic stroke (IS) outcome. A systematic search of two electronic databases (Medline and Embase) was conducted to identify studies that explored an association between PISS and IS outcome. The primary and secondary IS outcomes of interest were mortality and disability, respectively, with the latter defined as a score of 3 to 5 on th...

Risk of falling in a stroke unit after acute stroke: The Fall Study of Gothenburg (FallsGOT).

Science.gov (United States)

Persson, Carina U; Kjellberg, Sigvar; Lernfelt, Bodil; Westerlind, Ellen; Cruce, Malin; Hansson, Per-Olof

2018-03-01

This study aimed to investigate incidence of falls and different baseline variables and their association with falling during hospitalization in a stroke unit among patients with acute stroke. Prospective observational study. A stroke unit at a university hospital. A consecutive sample of stroke patients, out of which 504 were included, while 101 declined participation. The patients were assessed a mean of 1.7 days after admission and 3.8 days after stroke onset. The primary end-point was any fall, from admission to the stroke unit to discharge. Factors associated with falling were analysed using univariable and multivariable Cox hazard regression analyses. Independent variables were related to function, activity and participation, as well as personal and environmental factors. In total, 65 patients (13%) fell at least once. Factors statistically significantly associated with falling in the multivariable analysis were male sex (hazard ratio (HR): 1.88, 95% confidence interval (CI): 1.13-3.14, P = 0.015), use of a walking aid (HR: 2.11, 95% CI: 1.24-3.60, P = 0.006) and postural control as assessed with the modified version of the Postural Assessment Scale for Stroke Patients (SwePASS). No association was found with age, cognition or stroke severity, the HR for low SwePASS scores (⩽24) was 9.33 (95% CI: 2.19-39.78, P = 0.003) and for medium SwePASS scores (25-30) was 6.34 (95% CI: 1.46-27.51, P = 0.014), compared with high SwePASS scores (⩾31). Postural control, male sex and use of a walking aid are associated with falling during hospitalization after acute stroke.

Computational fluid dynamics applied to flows in an internal combustion engine

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Griffin, M. D.; Diwakar, R.; Anderson, J. D., Jr.; Jones, E.

1978-01-01

The reported investigation is a continuation of studies conducted by Diwakar et al. (1976) and Griffin et al. (1976), who reported the first computational fluid dynamic results for the two-dimensional flowfield for all four strokes of a reciprocating internal combustion (IC) engine cycle. An analysis of rectangular and cylindrical three-dimensional engine models is performed. The working fluid is assumed to be inviscid air of constant specific heats. Calculations are carried out of a four-stroke IC engine flowfield wherein detailed finite-rate chemical combustion of a gasoline-air mixture is included. The calculations remain basically inviscid, except that in some instances thermal conduction is included to allow a more realistic model of the localized sparking of the mixture. All the results of the investigation are obtained by means of an explicity time-dependent finite-difference technique, using a high-speed digital computer.

Epidemiology of stroke in the elderly in the Nordic countries. Incidence, survival, prevalence and risk factors

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Torgeir Engstad

2012-11-01

Full Text Available Objective: To review what is known at present with respect to incidence, survival, risk factors and prevalence among the elderly stroke patients in the Nordic countries.Method: This article is based mainly on literature identified through search engines (Mc Master Plus, Cochrane Library, Medline and PubMed, restricted to first-ever stroke in Nordic population-based studies and having applied to the standard WHO definition, a prospective study design and no upper age limit.Results: Data from the Nordic countries show an incidence rate of 1250 to 1796/100 000 in the age group 75-84, and 1628 to 2234 in those above 85 years. The incidence rates are higher among men, but women are expected to contribute more to incident cases due to their higher life expectancy. If the age-specific incidence of stroke remains stable, the proportion of stroke patients aged 80 years and older may reach 50% in a few decades. The elderly stroke patients have a higher 30-days case fatality, and a higher risk of dependency. Better treatment of stroke patients has improved the survival over the last two decades. The prevalence is expected to increase due to the decrease in lethality, a slower fall in incidence and a higher proportion of elderly. Cardiovascular risk factors increase with age. Hypertension is a major risk factor for stroke mortality in the elderly. Cardioembolic stroke due to atrial fibrillation is the most common stroke subtype in the elderly. Lifestyle risk factors are less prevalent in the older stroke patients.Conclusion: The growing proportion of elderly stroke patients is a major challenge for future stroke care. The elderly stroke patients have a different risk factor profile compared to younger stroke patients. Treatment should focus on regaining independency. The age-specific epidemiology of stroke needs to be studied further in large studies in order to plan for future health care.

Association of serial biochemical markers with acute ischemic stroke: the National Institute of Neurological Disorders and Stroke recombinant tissue plasminogen activator Stroke Study.

Science.gov (United States)

Jauch, Edward C; Lindsell, Christopher; Broderick, Joseph; Fagan, Susan C; Tilley, Barbara C; Levine, Steven R

2006-10-01

Biochemical markers of acute neuronal injury may aid in the diagnosis and management of acute ischemic stroke. Serum samples from the National Institute for Neurological Disorders and Stroke (NINDS) recombinant tissue plasminogen activator Stroke Study were analyzed for the presence of 4 biochemical markers of neuronal, glial, and endothelial cell injury. These biochemical markers, myelin basic protein (MBP), neuron-specific enolase (NSE), S100beta, and soluble thrombomodulin, were studied for an association with initial stroke severity, infarct volume, and functional outcome. In the original NINDS study, serum samples were drawn from all patients on presentation to the Emergency Department and at approximately 2 and 24 hours after initiation of study therapy. In this analysis, stored serum samples were available for 359 patients; 107 patients had samples for all 3 time points. Serum marker concentrations were measured by ELISA techniques. We examined the relation between serum concentrations of each marker and the degree of baseline neurological deficit, functional outcome, and infarct size on computed tomography at 24 hours and the effect of fibrinolytic therapy. Higher 24-hour peak concentrations of MBP, NSE, and S100beta were associated with higher National Institutes of Health Stroke Scale baseline scores (r=0.186, P<0.0001; r=0.117, P=0.032; and r=0.263, P<0.0001, respectively). Higher peak concentrations of MBP and S100beta (r=0.209, P<0.0001; r=0.239, P<0.0001) were associated with larger computed tomography lesion volumes. Patients with favorable outcomes had smaller changes in MBP and S100beta (P<0.05) concentrations in the first 24 hours. Soluble thrombomodulin was not associated with any severity or outcome measure. This study corroborates previous work demonstrating correlations of MBP, NSE, and S100beta with clinical and radiographic features in acute stroke. Despite significantly better outcomes in the tissue plasminogen activator-treated group, we

Disability pensions in relation to stroke: a population study

DEFF Research Database (Denmark)

Teasdale, T W; Engberg, A W

2002-01-01

the years 1979-1993 inclusive and were of pensionable age during that period. These patients were then screened in registers for death during the period 1979-1993 and for the award of disability pensions between the years 1979-1995. A total of 19476 (27%) patients had received a pension at some level. MAIN......PRIMARY OBJECTIVE: This study aimed to establish prevalence levels of disability pensions among stroke patients within a national population. RESEARCH DESIGN: From a Danish National register of hospitalizations, 72 673 patients were identified who had a discharge diagnosis of stroke between...... OUTCOMES AND RESULTS: Being in possession of a disability pension prior to stroke (n = 8565, 12%), rarely at the highest level, was not associated with elevated risk for stroke, or with elevated stroke mortality. It was, however, associated with a greater mortality subsequent to stroke. Disability pensions...

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

Science.gov (United States)

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.

Joinville stroke biobank: study protocol and first year’s results

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Leslie Ecker Ferreira

Full Text Available ABSTRACT Aiming to contribute to studies that use detailed clinical and genomic information of biobanks, we present the initial results of the first Latin American Stroke Biobank. Methods: Blood samples were collected from patients included in the Joinville Stroke Registry and four Brazilian cities. Demographic socio-economic data, cardiovascular risk factors, Causative Classification System for Ischemic Stroke, Trial of Org 10172 in Acute Stroke Treatment and National Institutes of Health scores, functional stroke status (modified Rankin and brain images were recorded. Additionally, controls from both geographic regions were recruited. High-molecular-weight genomic DNA was obtained from all participants. Results: A total of 2,688 patients and 3,282 controls were included. Among the patients, 76% had ischemic stroke, 12% transient ischemic attacks, 9% hemorrhagic stroke and 3% subarachnoid hemorrhage. Patients with undetermined ischemic stroke were most common according the Trial of Org 10172 in Acute Stroke Treatment (40% and Causative Classification System for Ischemic Stroke (47% criteria. A quarter of the patients were under 55 years of age at the first-ever episode. Conclusions: We established the Joinville Stroke Biobank and discuss its potential for contributing to the understanding of the risk factors leading to stroke.

Effect of heat transfer in cylinder on air quantity of 4-stroke cycle gasoline engine; 4 Stroke gasoline engine no kyunyu shinkiryo ni oyobosu cylinder nai dennetsu no eikyo

Energy Technology Data Exchange (ETDEWEB)

Yoshida, M.; Oguri, Y.; Suzuki, T. [Sophia University, Tokyo (Japan). Faculty of Science and Technology

2000-01-25

Many papers concerning air quantity of 4-stroke cycle gasoline engine have been published. It has been reported in these papers that heat transfer in surface of cylinder and inlet port gives big influence to the air quantity. But it has not been clear which influence of heat transfer in cylinder and inlet port is strong. So the authors derived a function of the air quantity thermodynamically considering heat transfer, and examined which of influence of heat transfer was strong. The results show ; (1) The influence of heat transfer in cylinder is small (about 1%) at full load, and is also small (about 5%) at light load. (2) Heat transfer in cylinder almost increases the air quantity. (3) The influence of heat transfer in inlet port decreases the air quantity with around 30% greatly. (author)

Optimism, well-being, depressive symptoms, and perceived physical health: a study among Stroke survivors.

Science.gov (United States)

Shifren, Kim; Anzaldi, Kristen

2018-01-01

The investigation of the relation of positive personality characteristics to mental and physical health among Stroke survivors has been a neglected area of research. The purpose of this study was to examine the relationship between optimism, well-being, depressive symptoms, and perceived physical health among Stroke survivors. It was hypothesized that Stroke survivors' optimism would explain variance in their physical health above and beyond the variance explained by demographic variables, diagnostic variables, and mental health. One hundred seventy-six Stroke survivors (97 females, 79 males) completed the Revised Life Orientation Test, the Center for Epidemiological Studies Depression Scale, two items on perceived physical health from the 36-item Short Form of the Medical Outcomes study, and the Identity scale of the Illness Perception Questionnaire. Pearson correlations, hierarchical regression analyses, and the PROCESS approach to determining mediators were used to assess hypothesized relations between variables. Stroke survivors' level of optimism explained additional variance in overall health in regression models controlling for demographic and diagnostic variables, and mental health. Analyses revealed that optimism played a partial mediator role between mental health (well-being, depressive symptoms and total score on CES-D) variables and overall health.

Clerget 100 hp heavy-oil engine

Science.gov (United States)

Leglise, Pierre

1931-01-01

A complete technical description of the Clerget heavy-oil engine is presented along with the general characteristics. The general characteristics are: 9 cylinders, bore 120 mm, stroke 130 mm, four-stroke cycle engine, rated power limited to 100 hp at 1800 rpm; weight 228 kg; propeller with direct drive and air cooling. Moving parts, engine block, and lubrication are all presented.

tDCS and Robotics on Upper Limb Stroke Rehabilitation: Effect Modification by Stroke Duration and Type of Stroke.

Science.gov (United States)

Straudi, Sofia; Fregni, Felipe; Martinuzzi, Carlotta; Pavarelli, Claudia; Salvioli, Stefano; Basaglia, Nino

2016-01-01

Objective. The aim of this exploratory pilot study is to test the effects of bilateral tDCS combined with upper extremity robot-assisted therapy (RAT) on stroke survivors. Methods. We enrolled 23 subjects who were allocated to 2 groups: RAT + real tDCS and RAT + sham-tDCS. Each patient underwent 10 sessions (5 sessions/week) over two weeks. Outcome measures were collected before and after treatment: (i) Fugl-Meyer Assessment-Upper Extremity (FMA-UE), (ii) Box and Block Test (BBT), and (iii) Motor Activity Log (MAL). Results. Both groups reported a significant improvement in FMA-UE score after treatment (p robotics on motor function. Patients with chronic and subcortical stroke benefited more from the treatments than patients with acute and cortical stroke, who presented very small changes. Conclusion. The additional use of bilateral tDCS to RAT seems to have a significant beneficial effect depending on the duration and type of stroke. These results should be verified by additional confirmatory studies.

Single-Cylinder Diesel Engine Tests with Unstabilized Water-in-Fuel Emulsions

Science.gov (United States)

1978-08-01

A single-cylinder, four-stroke cycle diesel engine was operated on unstabilized water-in-fuel emulsions. Two prototype devices were used to produce the emulsions on-line with the engine. More than 350 test points were run with baseline diesel fuel an...

"EMMA Study: a Brazilian community-based cohort study of stroke mortality and morbidity"

Directory of Open Access Journals (Sweden)

Alessandra Carvalho Goulart

Full Text Available ABSTRACT CONTEXT AND OBJECTIVE: Stroke has a high burden of disability and mortality. The aim here was to evaluate epidemiology, risk factors and prognosis for stroke in the EMMA Study (Study of Stroke Mortality and Morbidity. DESIGN AND SETTINGS: Prospective community-based cohort carried out in Hospital Universitário, University of São Paulo, 2006-2014. METHODS: Stroke data based on fatal and non-fatal events were assessed, including sociodemographic data, mortality and predictors, which were evaluated by means of logistic regression and survival analyses. RESULTS: Stroke subtype was better defined in the hospital setting than in the local community. In the hospital phase, around 70% were first events and the ischemic subtype. Among cerebrovascular risk factors, the frequency of alcohol intake was higher in hemorrhagic stroke (HS than in ischemic stroke (IS cases (35.4% versus 12.3%, P < 0.001. Low education was associated with higher risk of death, particularly after six months among IS cases (odds ratio, OR, 4.31; 95% confidence interval, CI, 1.34-13.91. The risk of death due to hemorrhagic stroke was greater than for ischemic stroke and reached its maximum 10 days after the event (OR: 3.31; 95% CI: 1.55-7.05. Four-year survival analysis on 665 cases of first stroke (82.6% ischemic and 17.4% hemorrhagic showed an overall survival rate of 48%. At four years, the highest risks of death were in relation to ischemic stroke and illiteracy (hazard ratio, HR: 1.83; 95% CI: 1.26-2.68 and diabetes (HR: 1.45; 95% CI: 1.07-1.97. Major depression presented worse one-year survival (HR: 4.60; 95% CI: 1.36-15.55. CONCLUSION: Over the long term, the EMMA database will provide additional information for planning resources destined for the public healthcare system.

CT perfusion-guided patient selection for endovascular recanalization in acute ischemic stroke: a multicenter study.

Science.gov (United States)

Turk, Aquilla S; Magarick, Jordan Asher; Frei, Don; Fargen, Kyle Michael; Chaudry, Imran; Holmstedt, Christine A; Nicholas, Joyce; Mocco, J; Turner, Raymond D; Huddle, Daniel; Loy, David; Bellon, Richard; Dooley, Gwendolyn; Adams, Robert; Whaley, Michelle; Fanale, Chris; Jauch, Edward

2013-11-01

The treatment of acute ischemic stroke is traditionally centered on time criteria, although recent evidence suggests that physiologic neuroimaging may be useful. In a multicenter study we evaluated the use of CT perfusion, regardless of time from symptom onset, in patients selected for intra-arterial treatment of ischemic stroke. Three medical centers retrospectively assessed stroke patients with a National Institute of Health Stroke Scale of ≥ 8, regardless of time from symptom onset. CT perfusion maps were qualitatively assessed. Patients with defined salvageable penumbra underwent intra-arterial revascularization of their occlusion. Functional outcome using the modified Rankin Score (mRS) was recorded. Two hundred and forty-seven patients were selected to undergo intra-arterial treatment based on CT perfusion imaging. The median time from symptom onset to procedure was 6 h. Patients were divided into two groups for analysis: ≤ 8 h and >8 h from symptom onset to endovascular procedure. We found no difference in functional outcome between the two groups (42.8% and 41.9% achieved 90-day mRS ≤ 2, respectively (p=1.0), and 54.9% vs 55.4% (p=1.0) achieved 90-day mRS ≤ 3, respectively). Overall, 48 patients (19.4%) had hemorrhages, of which 20 (8.0%) were symptomatic, with no difference between the groups (p=1.0). In a multicenter study, we demonstrated similar rates of good functional outcome and intracranial hemorrhage in patients with ischemic stroke when endovascular treatment was performed based on CT perfusion selection rather than time-guided selection. Our findings suggest that physiologic imaging-guided patient selection rather than time for endovascular reperfusion in ischemic stroke may be effective and safe.

Updating on Italian stroke units: the "CCM study".

Science.gov (United States)

Guidetti, D; Spallazzi, M; Toni, D; Rota, E; Morelli, N; Immovilli, P; Baldereschi, M; Polizzi, B M; Ferro, S; Inzitari, D

2013-07-01

The stroke units (SUs) have been demonstrated to be efficient and cost effective for acute stroke care. Nevertheless, the level of stroke unit implementation in Italy does not correspond to expectations yet. This study is a survey, which aims at assessing the current status of in-hospital stroke care in the Italian regions and at updating SUs. The survey was conducted by means of a semi-structured questionnaire, based on 18 stroke care "quality indicators", submitted to all the Italian centres that had taken part in the SITS-MOST study, and to other centres advised by the coordinator of SITS studies and by regional opinion leaders of stroke. SUs were defined as acute wards, with stroke-dedicated beds and dedicated teams that had been formally authorised to administer rt-PA. A statistical analysis was performed by a descriptive statistics and logistic regression model. The study was carried out from November 2009 to September 2010. A total of 168 forms were sent out and 153 replies received. Seven centres, which had not performed any thrombolytic treatment, and 16 which did not fulfil the criteria for the definition of SU were excluded from the study. Most of the centres reported more than 100 stroke patient admissions per year, i.e., 122 (84%) from 100 to 500, 18 (12%) more than 500. The 19% of the centres admitted more than 30% of patients within 3 h from the symptom onset and only 30% admitted more than 30% of patients within 4.5 h. The mean number of thrombolyses performed in the last 6 months was 10 for centres with a doctor on duty 24 h a day, 6 for those that have a doctor on duty from 8 a.m. to 8 p.m. and a doctor on call for night, and 5 for centres with a doctor on call 24 h a day. The territorial distribution of the SUs is remarkably heterogeneous: 87 SUs (67%) are located in the North of Italy, 28 (22%) in the central part of Italy and only 15 (11%) in the South. The last few years have witnessed a rise in both the diffusion of SUs and access to

Cause-Specific Mortality after Stroke: Relation to Age, Sex, Stroke Severity, and Risk Factors in a 10-Year Follow-Up Study

DEFF Research Database (Denmark)

Mogensen, UB; Olsen, TS; Andersen, KK

2013-01-01

We investigated cause-specific mortality in relation to age, sex, stroke severity, and cardiovascular risk factor profile in the Copenhagen Stroke Study cohort with 10 years of follow-up. In a Copenhagen community, all patients admitted to the hospital with stroke during 1992-1993 (n = 988) were.......2% for nonvascular disease. Death after stroke was associated with older age, male sex, greater stroke severity, and diabetes regardless of the cause of death. Previous stroke and hemorrhagic stroke were associated with death by stroke, ischemic heart disease was associated with death by heart/arterial disease...... registered on admission. Evaluation included stroke severity, computed tomography scan, and a cardiovascular risk profile. Cause of death within 10 years according to death certificate information was classified as stroke, heart/arterial disease, or nonvascular disease. Competing-risks analyses were...

Tribological Performance of Different Geometries of Piston Rings in Marine Diesel Engines

DEFF Research Database (Denmark)

Imran, Tajammal; Klit, Peder; Felter, Christian

Friction in the piston ring package (piston, piston rings and liner) is a major source of power consumption in two stroke marine diesel engines. It is well-known that a typical piston ring operates under full separation in the mid-part of the stroke, and in the mixed lubrication regime at the dead...

Renal dysfunction and chronic kidney disease in ischemic stroke and transient ischemic attack: A population-based study.

Science.gov (United States)

Hayden, Derek; McCarthy, Christine; Akijian, Layan; Callaly, Elizabeth; Ní Chróinín, Danielle; Horgan, Gillian; Kyne, Lorraine; Duggan, Joseph; Dolan, Eamon; O' Rourke, Killian; Williams, David; Murphy, Sean; O'Meara, Yvonne; Kelly, Peter J

2017-10-01

Background and purpose The prevalence of chronic kidney disease (estimated glomerular filtration rate (eGFR) chronic kidney disease (CKD)) in ischemic stroke and transient ischemic attack (TIA) is unknown, as estimates have been based on single-point estimates of renal function. Studies investigating the effect of renal dysfunction (eGFR < 60 mL/min per 1.73 m 2 , renal dysfunction) on post-stroke outcomes are limited to hospitalized cohorts and have provided conflicting results. Methods We investigated rates, determinants and outcomes of renal dysfunction in ischemic stroke and TIA in the North Dublin Population Stroke Study. We also investigate the persistence of renal dysfunction in 90-day survivors to determine the prevalence of CKD. Ascertainment included hot and cold pursuit using multiple overlapping sources. Survival analysis was performed using Kaplan-Meier survival curves and Cox proportional hazards modeling. Results In 547 patients (ischemic stroke in 76.4%, TIA in 23.6%), the mean eGFR at presentation was 63.7 mL/min/1.73 m 2 (SD 22.1). Renal dysfunction was observed in 44.6% (244/547). Among 90-day survivors, 31.2% (139/446) met criteria for CKD. After adjusting for age and stroke severity, eGFR < 45 mL/min/1.73 m 2 (hazard ratio 2.53, p = 0.01) independently predicted 28-day fatality but not at two years. Poor post-stroke functional outcome (Modified Rankin Scale 3-5) at two years was more common in those with renal dysfunction (52.5% vs. 20.6%, p < 0.001). After adjusting for age, stroke severity and pre-stroke disability, renal dysfunction (OR 2.17, p = 0.04) predicted poor functional outcome. Conclusion Renal dysfunction and CKD are common in ischemic stroke and TIA. Renal dysfunction is associated with considerable post-stroke morbidity and mortality. Further studies are needed to investigate if modifiable mechanisms underlie these associations.

Chuanxiong preparations for preventing stroke.

Science.gov (United States)

Yang, Xunzhe; Zeng, Xiaoxi; Wu, Taixiang

2010-01-20

Stroke is a major healthcare problem and is one of the leading causes of death and serious long-term disability. Prevention of stroke is considered an important strategy. Chuanxiong is traditionally used in China in the treatment and prevention of stroke. In recent years, Chinese researchers have developed new patented Chuanxiong preparations. To assess the effects and safety of Chuanxiong preparations in preventing stroke in high-risk adults. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2008, Issue 1), MEDLINE (1950 to March 2008), EMBASE (1980 to March 2008), AMED (1985 to March 2008), Chinese Biomedical Database (CBM) (1975 to March 2008), China National Knowledge Infrastructure (CNKI) (1994 to March 2008), and the VIP Database (1989 to March 2008). Trials registers were searched for ongoing studies. No language restrictions were applied. Randomised controlled trials (RCTs) studying the effects of Chuanxiong preparations in preventing stroke were included. Three reviewers independently selected studies for inclusion and two reviewers independently extracted data. Authors of identified RCTs were telephoned to confirm the randomisation procedure. Outcomes assessed included: stroke, composite cardiovascular outcomes, changes in cardiovascular and cerebrovascular haemodynamic indices and adverse events. Peto odds ratio (OR) with 95% confidence intervals (CI) were calculated for dichotomous variables and mean differences for continuous outcomes. Three RCTs (5042 participants) were included. One higher quality study (4415 participants) compared Nao-an capsule with aspirin for primary prevention in high-risk stroke populations. Nao-an capsule appeared to reduce the incidence of stroke compared with aspirin (OR 0.56 95% CI 0.33 to 0.96). One study of low methodological quality indicated that a self-prepared Xifenwan tablet reduced the incidence of stroke in people with transient ischaemia attack (TIA) (OR 0.18, 95% CI 0.04 to 0.78). The

Life satisfaction two-years after stroke onset: the effects of gender, sex occupational status, memory function and quality of life among stroke patients (Newsqol) and their family caregivers (Whoqol-bref) in Luxembourg

OpenAIRE

Baumann, Mich?le; Couffignal, Sophie; Le Bihan, Etienne; Chau, Nearkasen

2012-01-01

Abstract Background Life satisfaction (LS) of cerebrovascular disease survivors and their family caregivers may relate to socioeconomic factors, impaired functions, health-related quality of life (QoL), but their respective influences remain unclear. This study assessed, two years post-stroke onset, the effects of these factors on patients’ LS and family caregivers’ LS in Luxembourg. Methods All stroke patients admitted to all hospitals in Luxembourg were identified by the ‘Inspection Général...

In-hospital stroke: characteristics and outcomes.

LENUS (Irish Health Repository)

Briggs, R

2015-01-01

In-hospital stroke (IS) made up 6.5% of strokes recorded in the Irish National Stroke Register in 2012. International research has demonstrated poorer outcomes post IS compared to out of hospital stroke (OS). We aimed to profile all IS and OS over a 22 month period and compare the two groups by gathering data from the HIPE portal stroke register. The study site is a primary stroke centre. IS represented 11% (50\\/458) of total strokes with over half (27\\/50, 54%) admitted initially with medical complaints. IS patients had a significantly longer length of stay (79.2 +\\/- 87.4 days vs. 21.9 +\\/- 45.9 days, p < 0.01) and higher mortality (13\\/50 vs. 39\\/408, p < 0.01). Patients in the IS group were also less likely to receive stroke unit care (1\\/50 vs. 136\\/408, p < 0.01). This study demonstrates the significant morbidity and mortality associated with IS and highlights the need for efforts to be made to optimize identification and management of acute stroke in this cohort.

Improving post-stroke dysphagia outcomes through a standardized and multidisciplinary protocol: an exploratory cohort study.

Science.gov (United States)

Gandolfi, Marialuisa; Smania, Nicola; Bisoffi, Giulia; Squaquara, Teresa; Zuccher, Paola; Mazzucco, Sara

2014-12-01

Stroke is a major cause of dysphagia. Few studies to date have reported on standardized multidisciplinary protocolized approaches to the management of post-stroke dysphagia. The aim of this retrospective cohort study was to evaluate the impact of a standardized multidisciplinary protocol on clinical outcomes in patients with post-stroke dysphagia. We performed retrospective chart reviews of patients with post-stroke dysphagia admitted to the neurological ward of Verona University Hospital from 2004 to 2008. Outcomes after usual treatment for dysphagia (T- group) were compared versus outcomes after treatment under a standardized diagnostic and rehabilitative multidisciplinary protocol (T+ group). Outcome measures were death, pneumonia on X-ray, need for respiratory support, and proportion of patients on tube feeding at discharge. Of the 378 patients admitted with stroke, 84 had dysphagia and were enrolled in the study. A significantly lower risk of in-hospital death (odds ratio [OR] 0.20 [0.53-0.78]), pneumonia (OR 0.33 [0.10-1.03]), need for respiratory support (OR 0.48 [0.14-1.66]), and tube feeding at discharge (OR 0.30 [0.09-0.91]) was recorded for the T+ group (N = 39) as compared to the T- group (N = 45). The adjusted OR showed no difference between the two groups for in-hospital death and tube feeding at discharge. Use of a standardized multidisciplinary protocolized approach to the management of post-stroke dysphagia may significantly reduce rates of aspiration pneumonia, in-hospital mortality, and tube feeding in dysphagic stroke survivors. Consistent with the study's exploratory purposes, our findings suggest that the multidisciplinary protocol applied in this study offers an effective model of management of post-stroke dysphagia.

Effects of heating energy and heating position on the conversion characteristics of the catalyst of a four-stroke motorcycle engine in cold start conditions

International Nuclear Information System (INIS)

Horng, R.-F.; Chou, H.-M.; Hsu, T.-C.

2004-01-01

The effects of heating energy and heating position on the conversion efficiency of an electrically heated catalyst of a four stroke motorcycle engine under cold start conditions were investigated in this study. In general, during cold start, the operating temperatures of a four stroke motorcycle engine and its catalyst would not be optimized. It was found in this paper that by applying heat to the catalyst however, the reaction of the catalyst could be promoted, which, consequently, improved the conversion efficiency. The experimented parameters were heating energy, heating position, heating temperature and the carbon monoxide (CO) setting level. The heating temperatures included 100, 140 and 180 deg. C, while three different heating powers and six different heating positions were used. The CO levels were set as 1.0%, 1.8% and 2.3%. The best CO conversion efficiency was obtained by applying heating at the inlet of the catalyst. It was revealed that a high heating power induced a high temperature rising rate and, consequently, a high CO conversion efficiency. In terms of energy economy efficiency, however, heating at the mid-section of the catalyst gave the best results and through a relatively low heating power

Neighborhood disadvantage and ischemic stroke: the Cardiovascular Health Study (CHS).

Science.gov (United States)

Brown, Arleen F; Liang, Li-Jung; Vassar, Stefanie D; Stein-Merkin, Sharon; Longstreth, W T; Ovbiagele, Bruce; Yan, Tingjian; Escarce, José J

2011-12-01

Neighborhood characteristics may influence the risk of stroke and contribute to socioeconomic disparities in stroke incidence. The objectives of this study were to examine the relationship between neighborhood socioeconomic status and incident ischemic stroke and examine potential mediators of these associations. We analyzed data from 3834 whites and 785 blacks enrolled in the Cardiovascular Health Study, a multicenter, population-based, longitudinal study of adults ages≥65 years from 4 US counties. The primary outcome was adjudicated incident ischemic stroke. Neighborhood socioeconomic status was measured using a composite of 6 census tract variables. Race-stratified multilevel Cox proportional hazard models were constructed adjusted for sociodemographic, behavioral, and biological risk factors. Among whites, in models adjusted for sociodemographic characteristics, stroke hazard was significantly higher among residents of neighborhoods in the lowest compared with the highest neighborhood socioeconomic status quartile (hazard ratio, 1.32; 95% CI, 1.01-1.72) with greater attenuation of the hazard ratio after adjustment for biological risk factors (hazard ratio, 1.16; 0.88-1.52) than for behavioral risk factors (hazard ratio, 1.30; 0.99-1.70). Among blacks, we found no significant associations between neighborhood socioeconomic status and ischemic stroke. Higher risk of incident ischemic stroke was observed in the most disadvantaged neighborhoods among whites, but not among blacks. The relationship between neighborhood socioeconomic status and stroke among whites appears to be mediated more strongly by biological than behavioral risk factors.

Effect of two 12-minute culturally targeted films on intent to call 911 for stroke.

Science.gov (United States)

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.

Fast Recognition of BCI-Inefficient Users Using Physiological Features from EEG Signals: A Screening Study of Stroke Patients.

Science.gov (United States)

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 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

Science.gov (United States)

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 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

Modeling of Lightning Strokes Using Two-Peaked Channel-Base Currents

Directory of Open Access Journals (Sweden)

V. Javor

2012-01-01

Full Text Available Lightning electromagnetic field is obtained by using “engineering” models of lightning return strokes and new channel-base current functions and the results are presented in this paper. Experimentally measured channel-base currents are approximated not only with functions having two-peaked waveshapes but also with the one-peaked function so as usually used in the literature. These functions are simple to be applied in any “engineering” or electromagnetic model as well. For the three “engineering” models: transmission line model (without the peak current decay, transmission line model with linear decay, and transmission line model with exponential decay with height, the comparison of electric and magnetic field components at different distances from the lightning channel-base is presented in the case of a perfectly conducting ground. Different heights of lightning channels are also considered. These results enable analysis of advantages/shortages of the used return stroke models according to the electromagnetic field features to be achieved, as obtained by measurements.

A study on the influence of corona on currents and electromagnetic fields predicted by a nonlinear lightning return-stroke model

Science.gov (United States)

De Conti, Alberto; Silveira, Fernando H.; Visacro, Silvério

2014-05-01

This paper investigates the influence of corona on currents and electromagnetic fields predicted by a return-stroke model that represents the lightning channel as a nonuniform transmission line with time-varying (nonlinear) resistance. The corona model used in this paper allows the calculation of corona currents as a function of the radial electric field in the vicinity of the channel. A parametric study is presented to investigate the influence of corona parameters, such as the breakdown electric field and the critical electric field for the stable propagation of streamers, on predicted currents and electromagnetic fields. The results show that, regardless of the assumed corona parameters, the incorporation of corona into the nonuniform and nonlinear transmission line model under investigation modifies the model predictions so that they consistently reproduce most of the typical features of experimentally observed lightning electromagnetic fields and return-stroke speed profiles. In particular, it is shown that the proposed model leads to close vertical electric fields presenting waveforms, amplitudes, and decay with distance in good agreement with dart leader electric field changes measured in triggered lightning experiments. A comparison with popular engineering return-stroke models further confirms the model's ability to predict consistent electric field waveforms in the close vicinity of the channel. Some differences observed in the field amplitudes calculated with the different models can be related to the fact that current distortion, while present in the proposed model, is ultimately neglected in the considered engineering return-stroke models.

Clinimetrics & determinants of outcome after stroke

NARCIS (Netherlands)

Schepers, V.P.M.

2006-01-01

This thesis is based on findings of the Functional Prognostication and disability study on stroke, which had two main objectives: (1) to examine which outcome measures are most appropriate, and especially most responsive, for the assessment of functional outcome in stroke patients and (2) to study

Effect of Formal Education on Vascular Cognitive Impairment after Stroke: A Meta-analysis and Study in Young-Stroke Patients.

Science.gov (United States)

Kessels, Roy P C; Eikelboom, Willem Sake; Schaapsmeerders, Pauline; Maaijwee, Noortje A M; Arntz, Renate M; van Dijk, Ewoud J; de Leeuw, Frank-Erik

2017-03-01

The extent of vascular cognitive impairment (VCI) after stroke varies greatly across individuals, even when the same amount of brain damage is present. Education level is a potentially protective factor explaining these differences, but results on its effects on VCI are inconclusive. First, we performed a meta-analysis on formal education and VCI, identifying 21 studies (N=7770). Second, we examined the effect of formal education on VCI in young-stroke patients who were cognitively assessed on average 11.0 (SD=8.2) years post-stroke (the FUTURE study cohort). The total sample consisted of 277 young-stroke patients with a mean age at follow-up 50.9 (SD=10.3). Age and education-adjusted expected scores were computed using 146 matched stroke-free controls. The meta-analysis showed an overall effect size (z') of 0.25 (95% confidence interval [0.18-0.31]), indicating that formal education level had a small to medium effect on VCI. Analyses of the FUTURE data showed that the effect of education on post-stroke executive dysfunction was mediated by age (β age -0.015; peducation patients (χ2(2)=9.8; peducation level was found to be related to post-stroke VCI in previous research, the effects were small. Further analysis in a large stroke cohort showed that these education effects were fully mediated by age, even in relatively young stroke patients. Education level in and of itself does not appear to be a valid indicator of cognitive reserve. Multi-indicator methods may be more valid, but have not been studied in relation to VCI. (JINS, 2017, 23, 223-238).

Trajectories of health-related quality of life after stroke : results from a one-year prospective cohort study

NARCIS (Netherlands)

van Mierlo, Maria; van Heugten, Caroline; Post, Marcel W M; Hoekstra, Trynke; Visser-Meily, Anne

2018-01-01

PURPOSE: To identify trajectories of physical and psychosocial health-related quality of life (HRQoL) from two months to one-year post stroke and to determine the factors that are associated with trajectory membership. METHOD: Multicenter prospective cohort study in which 351 stroke patients were

Depression and young age impact on hip fracture subsequent to stroke: A population-based cohort study.

Science.gov (United States)

Yeh, Hui-Fang; Hsu, Yao-Chun; Clinciu, Daniel L; Tung, Heng-Hsin; Yen, Yung-Chieh; Kuo, Hung-Chang

2018-06-03

The purpose of this study is to identify whether depression and other associated factors in stroke are related to subsequent hip fracture. There are very few studies that focus on depression and demographic impact on subsequent hip fracture after a stroke. This a retrospective cohort study design. The Taiwan Longitudinal Health Insurance Database between 1997 and 2010 was used. Two stroke patient cohorts were analysed: (1) depression within 1 year after newly diagnosed strokes; (2) without depression within 1 year after newly diagnosed strokes. Demographic characteristics, comorbidities, and hip fracture were compared using the Fine and Gray regression model for subdistribution hazard ratios. Patients with depression showed a higher risk of hip fracture (95% CI, 0.99-1.66). Depression was associated with increased risk of hip fracture for patients below 50 years old (95% CI, 1.45-7.34). Comorbidities and gender showed no significant correlation with hip fracture risk in the depressed or nondepressed groups. Poststroke depression was a significant contributor to hip fracture in patients who suffered strokes and had more negative impact on the younger population, regardless of the gender and presence of comorbidities. © 2018 John Wiley & Sons Australia, Ltd.

Recovery of slow-5 oscillations in a longitudinal study of ischemic stroke patients.

Science.gov (United States)

La, C; Nair, V A; Mossahebi, P; Stamm, J; Birn, R; Meyerand, M E; Prabhakaran, V

2016-01-01

Functional networks in resting-state fMRI are identified by characteristics of their intrinsic low-frequency oscillations, more specifically in terms of their synchronicity. With advanced aging and in clinical populations, this synchronicity among functionally linked regions is known to decrease and become disrupted, which may be associated with observed cognitive and behavioral changes. Previous work from our group has revealed that oscillations within the slow-5 frequency range (0.01-0.027 Hz) are particularly susceptible to disruptions in aging and following a stroke. In this study, we characterized longitudinally the changes in the slow-5 oscillations in stroke patients across two different time-points. We followed a group of ischemic stroke patients (n = 20) and another group of healthy older adults (n = 14) over two visits separated by a minimum of three months (average of 9 months). For the stroke patients, one visit occurred in their subacute window (10 days to 6 months after stroke onset), the other took place in their chronic window (> 6 months after stroke). Using a mid-order group ICA method on 10-minutes eyes-closed resting-state fMRI data, we assessed the frequency distributions of a component's representative time-courses for differences in regards to slow-5 spectral power. First, our stroke patients, in their subacute stage, exhibited lower amplitude slow-5 oscillations in comparison to their healthy counterparts. Second, over time in their chronic stage, those same patients showed a recovery of those oscillations, reaching near equivalence to the healthy older adult group. Our results indicate the possibility of an eventual recovery of those initially disrupted network oscillations to a near-normal level, providing potentially a biomarker for stroke recovery of the cortical system. This finding opens new avenues in infra-slow oscillation research and could serve as a useful biomarker in future treatments aimed at recovery.

Recovery of slow-5 oscillations in a longitudinal study of ischemic stroke patients

Directory of Open Access Journals (Sweden)

C. La

2016-01-01

Full Text Available Functional networks in resting-state fMRI are identified by characteristics of their intrinsic low-frequency oscillations, more specifically in terms of their synchronicity. With advanced aging and in clinical populations, this synchronicity among functionally linked regions is known to decrease and become disrupted, which may be associated with observed cognitive and behavioral changes. Previous work from our group has revealed that oscillations within the slow-5 frequency range (0.01–0.027 Hz are particularly susceptible to disruptions in aging and following a stroke. In this study, we characterized longitudinally the changes in the slow-5 oscillations in stroke patients across two different time-points. We followed a group of ischemic stroke patients (n = 20 and another group of healthy older adults (n = 14 over two visits separated by a minimum of three months (average of 9 months. For the stroke patients, one visit occurred in their subacute window (10 days to 6 months after stroke onset, the other took place in their chronic window (>6 months after stroke. Using a mid-order group ICA method on 10-minutes eyes-closed resting-state fMRI data, we assessed the frequency distributions of a component's representative time-courses for differences in regards to slow-5 spectral power. First, our stroke patients, in their subacute stage, exhibited lower amplitude slow-5 oscillations in comparison to their healthy counterparts. Second, over time in their chronic stage, those same patients showed a recovery of those oscillations, reaching near equivalence to the healthy older adult group. Our results indicate the possibility of an eventual recovery of those initially disrupted network oscillations to a near-normal level, providing potentially a biomarker for stroke recovery of the cortical system. This finding opens new avenues in infra-slow oscillation research and could serve as a useful biomarker in future treatments aimed at recovery.

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

Science.gov (United States)

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.

A new and efficient mechanism for spark ignition engines

International Nuclear Information System (INIS)

Shadloo, M.S.; Poultangari, R.; Abdollahzadeh Jamalabadi, M.Y.; Rashidi, M.M.

2015-01-01

Highlights: • A new slider–crank mechanism, with superior performance is presented. • Thermodynamic processes as well as vibration and internal forces have been modeled. • Comparison with the conventional four-stroke spark ignition engines is made. • Advantages and disadvantages of the proposed mechanism are discussed. - Abstract: In this paper a new symmetrical crank and slider mechanism is proposed and a zero dimensional model is utilized to study its combustion performance enhancement in a four-stroke spark ignition (SI) engine. The main features of this new mechanism are superior thermodynamic efficiency, lower internal frictions, and lower pollutants. Comparison is made between its performance and that of the conventional four-stroke SI engines. Presented mechanism is designed to provide better fuel consumption of internal combustion engines. These advantages over standard engine are achieved through synthesis of new mechanism. Numerical calculation have been performed for several cases of different mechanism parameters, compression ratio and engine speed. A comprehensive comparison between their thermodynamic processes as well as vibration and internal forces has been done. Calculated efficiency and power diagrams are plotted and compared with performance of a conventional SI engine. Advantages and disadvantages of the proposed mechanism are discussed in details

Stroke Experiences in Weblogs: A Feasibility Study of Sex Differences

Science.gov (United States)

Koh, Sukjin; Gordon, Andrew S; Wienberg, Christopher; Sood, Sara O; Morley, Stephanie

2014-01-01

Background Research on cerebral stroke symptoms using hospital records has reported that women experience more nontraditional symptoms of stroke (eg, mental status change, pain) than men do. This is an important issue because nontraditional symptoms may delay the decision to get medical assistance and increase the difficulty of correct diagnosis. In the present study, we investigate sex differences in the stroke experience as described in stories on weblogs. Objective The goal of this study was to investigate the feasibility of using the Internet as a source of data for basic research on stroke experiences. Methods Stroke experiences described in blogs were identified by using StoryUpgrade, a program that searches blog posts using a fictional prototype story. In this study, the prototype story was a description of a stroke experience. Retrieved stories coded by the researchers as relevant were used to update the search query and retrieve more stories using relevance feedback. Stories were coded for first- or third-person narrator, traditional and nontraditional patient symptoms, type of stroke, patient sex and age, delay before seeking medical assistance, and delay at hospital and in treatment. Results There were 191 relevant stroke stories of which 174 stories reported symptoms (52.3% female and 47.7% male patients). There were no sex differences for each traditional or nontraditional stroke symptom by chi-square analysis (all Ps>.05). Type of narrator, however, affected report of traditional and nontraditional symptoms. Female first-person narrators (ie, the patient) were more likely to report mental status change (56.3%, 27/48) than male first-person narrators (36.4%, 16/44), a marginally significant effect by logistic regression (P=.056), whereas reports of third-person narrators did not differ for women (27.9%, 12/43) and men (28.2%, 11/39) patients. There were more reports of at least 1 nontraditional symptom in the 92 first-person reports (44.6%, 41/92) than

Stroke experiences in weblogs: a feasibility study of sex differences.

Science.gov (United States)

Koh, Sukjin; Gordon, Andrew S; Wienberg, Christopher; Sood, Sara O; Morley, Stephanie; Burke, Deborah M

2014-03-19

Research on cerebral stroke symptoms using hospital records has reported that women experience more nontraditional symptoms of stroke (eg, mental status change, pain) than men do. This is an important issue because nontraditional symptoms may delay the decision to get medical assistance and increase the difficulty of correct diagnosis. In the present study, we investigate sex differences in the stroke experience as described in stories on weblogs. The goal of this study was to investigate the feasibility of using the Internet as a source of data for basic research on stroke experiences. Stroke experiences described in blogs were identified by using StoryUpgrade, a program that searches blog posts using a fictional prototype story. In this study, the prototype story was a description of a stroke experience. Retrieved stories coded by the researchers as relevant were used to update the search query and retrieve more stories using relevance feedback. Stories were coded for first- or third-person narrator, traditional and nontraditional patient symptoms, type of stroke, patient sex and age, delay before seeking medical assistance, and delay at hospital and in treatment. There were 191 relevant stroke stories of which 174 stories reported symptoms (52.3% female and 47.7% male patients). There were no sex differences for each traditional or nontraditional stroke symptom by chi-square analysis (all Ps>.05). Type of narrator, however, affected report of traditional and nontraditional symptoms. Female first-person narrators (ie, the patient) were more likely to report mental status change (56.3%, 27/48) than male first-person narrators (36.4%, 16/44), a marginally significant effect by logistic regression (P=.056), whereas reports of third-person narrators did not differ for women (27.9%, 12/43) and men (28.2%, 11/39) patients. There were more reports of at least 1 nontraditional symptom in the 92 first-person reports (44.6%, 41/92) than in the 82 third-person reports (25

Satisfaction with palliative care after stroke: a prospective cohort study.

Science.gov (United States)

Blacquiere, Dylan; Bhimji, Khadija; Meggison, Hilary; Sinclair, John; Sharma, Michael

2013-09-01

The determinants of satisfaction for families of acute stroke patients receiving palliative care have not been extensively studied. We surveyed families to determine how they perceived palliative care after stroke. Families of patients palliated after ischemic stroke, intracerebral, or subarachnoid hemorrhage were approached. Four weeks after the patient's death, families were administered the After-Death Bereaved Family Member Interview to determine satisfaction with the care provided. Fifteen families participated. Families were most satisfied with participation in decision making and least satisfied with attention to emotional needs. In stroke-specific domains, families had less satisfaction with artificial feeding, hydration, and communication. Overall satisfaction was high (9.04 out of 10). Families of patients receiving palliative care at our institution showed generally high satisfaction with palliation after stroke; specific domains were identified for improvement. Further study in larger populations is required.

Protocol and methodology of the Stroke in Young Fabry Patients (sifap1) study: a prospective multicenter European study of 5,024 young stroke patients aged 18-55 years.

LENUS (Irish Health Repository)

Rolfs, Arndt

2011-01-01

Stroke in the young has not been thoroughly investigated with most previous studies based on a small number of patients from single centers. Furthermore, recent reports indicate that Fabry disease may be a significant cause for young stroke. The primary aim of our study was to determine the prevalence of Fabry disease in young stroke patients, while the secondary aim was to describe patterns of stroke in young patients.

Risk factors, aetiology and outcome of ischaemic stroke in young adults: the Swiss Young Stroke Study (SYSS).

Science.gov (United States)

Goeggel Simonetti, Barbara; Mono, Marie-Luise; Huynh-Do, Uyen; Michel, Patrik; Odier, Celine; Sztajzel, Roman; Lyrer, Philippe; Engelter, Stefan T; Bonati, Leo; Gensicke, Henrik; Traenka, Christopher; Tettenborn, Barbara; Weder, Bruno; Fischer, Urs; Galimanis, Aekaterini; Jung, Simon; Luedi, Rudolf; De Marchis, Gian Marco; Weck, Anja; Cereda, Carlo W; Baumgartner, Ralf; Bassetti, Claudio L; Mattle, Heinrich P; Nedeltchev, Krassen; Arnold, Marcel

2015-09-01

Ischaemic stroke (IS) in young adults has been increasingly recognized as a serious health condition. Stroke aetiology is different in young adults than in the older population. This study aimed to investigate aetiology and risk factors, and to search for predictors of outcome and recurrence in young IS patients. We conducted a prospective multicentre study of consecutive IS patients aged 16-55 years. Baseline demographic data, risk factors, stroke aetiology including systematic genetic screening for Fabry disease and severity were assessed and related to functional neurological outcome (modified Rankin Scale, mRS), case fatality, employment status, place of residence, and recurrent cerebrovascular events at 3 months. In 624 IS patients (60% men), median age was 46 (IQR 39-51) years and median NIHSS on admission 3 (IQR 1-8). Modifiable vascular risk factors were found in 73%. Stroke aetiology was mostly cardioembolism (32%) and of other defined origin (24%), including cervicocerebral artery dissection (17%). Fabry disease was diagnosed in 2 patients (0.3%). Aetiology remained unknown in 20%. Outcome at 3 months was favourable (mRS 0-1) in 61% and fatal in 2.9%. Stroke severity (p young adults with IS had modifiable vascular risk factors, emphasizing the importance of prevention strategies. Outcome was unfavourable in more than a third of patients and was associated with initial stroke severity and diabetes mellitus. Previous cerebrovascular events predicted recurrent ones.

Effect of acupuncture on insomnia following stroke: study protocol for a randomized controlled trial.

Science.gov (United States)

Cao, Yan; Yin, Xuan; Soto-Aguilar, Francisca; Liu, Yiping; Yin, Ping; Wu, Junyi; Zhu, Bochang; Li, Wentao; Lao, Lixing; Xu, Shifen

2016-11-16

The incidence, mortality, and prevalence of stroke are high in China. Stroke is commonly associated with insomnia; both insomnia and stroke have been effectively treated with acupuncture for a long time. The aim of this proposed trial is to assess the therapeutic effect of acupuncture on insomnia following stroke. This proposed study is a single-center, single-blinded (patient-assessor-blinded), parallel-group randomized controlled trial. We will randomly assign 60 participants with insomnia following stroke into two groups in a 1:1 ratio. The intervention group will undergo traditional acupuncture that achieves the De-qi sensation, and the control group will receive sham acupuncture without needle insertion. The same acupoints (DU20, DU24, EX-HN3, EX-HN22, HT7, and SP6) will be used in both groups. Treatments will be given to all participants three times a week for the subsequent 4 weeks. The primary outcome will be the Pittsburgh Sleep Quality Index. The secondary outcomes will be: the Insomnia Severity Index; sleep efficacy, sleep awakenings, and total sleep time recorded via actigraphy; the National Institutes of Health Stroke Scale; the Stroke-Specific Quality of Life score; the Hospital Anxiety and Depression Scale. The use of estazolam will be permitted and regulated under certain conditions. Outcomes will be assessed at baseline, 2 weeks after treatment commencement, 4 weeks after treatment commencement, and at the 8-week follow-up. This proposed study will contribute to expanding knowledge about acupuncture treatment for insomnia following stroke. This will be a high-quality randomized controlled trial with strict methodology and few design deficits. It will investigate the effectiveness of acupuncture as an alternative treatment for insomnia following stroke. Chinese Clinical Trial Registry identifier: ChiCTR-IIC-16008382 . Registered on 28 April 2016.

mStroke: "Mobile Stroke"-Improving Acute Stroke Care with Smartphone Technology.

Science.gov (United States)

Andrew, Benjamin Y; Stack, Colleen M; Yang, Julian P; Dodds, Jodi A

2017-07-01

This study aimed to evaluate the effect of method and time of system activation on clinical metrics in cases utilizing the Stop Stroke (Pulsara, Inc.) mobile acute stroke care coordination application. A retrospective cohort analysis of stroke codes at 12 medical centers using Stop Stroke from March 2013 to May 2016 was performed. Comparison of metrics (door-to-needle time [DTN] and door-to-CT time [DTC], and rate of DTN ≤ 60 minutes [goal DTN]) was performed between subgroups based on method (emergency medical service [EMS] versus emergency department [ED]) and time of activation. Effects were adjusted for confounders (age, sex, National Institutes of Health Stroke Scale [NIHSS] score) using multiple linear and logistic regression. The final dataset included 2589 cases. Cases activated by EMS were more severe (median NIHSS score 8 versus 4, P technology provides unique insight into acute stroke codes. Activation of mobile electronic stroke coordination in the field appears to promote a more expedited and successful care process. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Analysis and simulation of Wiseman hypocycloid engine

Directory of Open Access Journals (Sweden)

Priyesh Ray

2014-12-01

Full Text Available This research studies an alternative to the slider-crank mechanism for internal combustion engines, which was proposed by the Wiseman Technologies Inc. Their design involved replacing the crankshaft with a hypocycloid gear assembly. The unique hypocycloid gear arrangement allowed the piston and connecting rod to move in a straight line creating a perfect sinusoidal motion, without any side loads. In this work, the Wiseman hypocycloid engine was modeled in a commercial engine simulation software and compared to slider-crank engine of the same size. The engine’s performance was studied, while operating on diesel, ethanol, and gasoline fuel. Furthermore, a scaling analysis on the Wiseman engine prototypes was carried out to understand how the performance of the engine is affected by increasing the output power and cylinder displacement. It was found that the existing 30cc Wiseman engine produced about 7% less power at peak speeds than the slider-crank engine of the same size. These results were concurrent with the dynamometer tests performed in the past. It also produced lower torque and was about 6% less fuel efficient than the slider-crank engine. The four-stroke diesel variant of the same Wiseman engine performed better than the two-stroke gasoline version. The Wiseman engine with a contra piston (that allowed to vary the compression ratio showed poor fuel efficiency but produced higher torque when operating on E85 fuel. It also produced about 1.4% more power than while running on gasoline. While analyzing effects of the engine size on the Wiseman hypocycloid engine prototypes, it was found that the engines performed better in terms of power, torque, fuel efficiency, and cylinder brake mean effective pressure as the displacement increased. The 30 horsepower (HP conceptual Wiseman prototype, while operating on E85, produced the most optimum results in all aspects, and the diesel test for the same engine proved to be the most fuel efficient.

Suicidal ideation and attempts in patients with stroke: a population-based study.

Science.gov (United States)

Chung, Jae Ho; Kim, Jung Bin; Kim, Ji Hyun

2016-10-01

Stroke is known to be associated with an increase in the risk for suicide. However, there are very few population-based studies investigating the risk of suicidal ideation and attempts in patients with stroke. The purpose of this study was to compare the risk of suicidal ideation and attempts between patients with stroke and population without stroke using nationwide survey data. Individual-level data were obtained from 228,735 participants (4560 with stroke and 224,175 without stroke) of the 2013 Korean Community Health Survey. Demographic characteristics, socioeconomic status, physical health status, and mental health status were compared between patients with stroke and population without stroke. Multivariable logistic regression was performed to investigate the independent effects of the stroke on suicidal ideation and attempts. Stroke patients had more depressive mood (12.6 %) than population without stroke (5.7 %, p suicidal ideation (24.4 %) and attempts (1.3 %) than population without stroke (9.8 and 0.4 %, respectively; both p suicidal ideation (OR 1.65, 95 % CI 1.52-1.79) and suicidal attempts (OR 1.64, 95 % CI 1.21-2.22), adjusting for demographics, socioeconomic factors, and physical health and mental health factors. We found that stroke increased the risk for suicidal ideation and attempts, independent of other factors that are known to be associated with suicidality, suggesting that stroke per se may be an independent risk factor for suicidality.

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

Science.gov (United States)

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

Science.gov (United States)

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.

Increased risk of ischemic stroke in young patients with ankylosing spondylitis: a population-based longitudinal follow-up study.

Science.gov (United States)

Lin, Chia-Wei; Huang, Ya-Ping; Chiu, Yueh-Hsia; Ho, Yu-Tsun; Pan, Shin-Liang

2014-01-01

Prospective data on the association between ischemic stroke and ankylosing spondylitis (AS) in the young are sparse. The purpose of this population-based, age- and sex-matched longitudinal follow-up study was to investigate the risk of developing ischemic stroke in young patients with AS. A total of 4562 patients aged 18- to 45-year-old with at least two ambulatory visits in 2001 with a principal diagnosis of AS were enrolled in the AS group. The non-AS group consisted of 22810 age- and sex-matched, randomly sampled subjects without AS. The two-year ischemic stroke-free survival rate for each group were calculated using the Kaplan-Meier method. Cox proportional hazards regression analysis was used to estimate the hazard ratio of ischemic stroke after adjusting for demographic and clinical covariates. During follow-up, 21 patients in the AS group and 53 in the non-AS group developed ischemic stroke. The ischemic stroke-free survival rate over the 2 year follow-up was lower in the AS group than the non-AS group (p = 0.0021). The crude hazard ratio of ischemic stroke for the AS group was 1.98 (95% CI, 1.20-3.29; p = 0.0079) and the adjusted hazard ratio after controlling for demographic and comorbid medical disorders was 1.93 (95% CI, 1.16-3.20; p = 0.0110). Our study showed an increased risk of developing ischemic stroke in young patients with AS.

Continuous Identification of a Four-Stroke SI Engine

DEFF Research Database (Denmark)

Melgaard, Henrik; Hendricks, Elbert; Madsen, Henrik

1990-01-01

Compact engine models often consist of a set of nonlinear differential equations which predict the time development of the mean value of the engine state variables (and perhaps some internal variables): such models are sometimes called mean value engine models. Currently a great deal of attention...... and Maximum Likelihood estimation). These techniques have been applied to a four cylinder SI engine. The results include an identification of the most important parameters and time constants of the engine. These are of interest for the construction of engine simulation models, for control studies...... is focused on constructing such continuous time models and on finding their parameters. This paper shows, that it is possible to identify an engine model from a linearized version of a mean value model for a CFI four-cycle spark ignition (SI) engine. Such an approach is useful because it preserves a physical...

Effect of pre-stroke use of ACE inhibitors on ischemic stroke severity

Directory of Open Access Journals (Sweden)

Caplan Louis

2005-06-01

Full Text Available Abstract Background Recent trials suggest that angiotensin-converting enzyme inhibitors (ACEI are effective in prevention of ischemic stroke, as measured by reduced stroke incidence. We aimed to compare stroke severity between stroke patients who were taking ACEI before their stroke onset and those who were not, to examine the effects of pretreatment with ACEI on ischemic stroke severity. Methods We retrospectively studied 126 consecutive patients presenting within 24 hours of ischemic stroke onset, as confirmed by diffusion-weighted magnetic resonance imaging (DWI. We calculated the NIHSS score at presentation, as the primary measure of clinical stroke severity, and categorized stroke severity as mild (NIHSS [less than or equal to] 7, moderate (NIHSS 8–13 or severe (NIHSS [greater than or equal to] 14. We analyzed demographic data, risk-factor profile, blood pressure (BP and medications on admissions, and determined stroke mechanism according to TOAST criteria. We also measured the volumes of admission diffusion- and perfusion-weighted (DWI /PWI magnetic resonance imaging lesions, as a secondary measure of ischemic tissue volume. We compared these variables among patients on ACEI and those who were not. Results Thirty- three patients (26% were on ACE-inhibitors. The overall median baseline NIHSS score was 5.5 (range 2–21 among ACEI-treated patients vs. 9 (range 1–36 in non-ACEI patients (p = 0.036. Patients on ACEI prior to their stroke had more mild and less severe strokes, and smaller DWI and PWI lesion volumes compared to non-ACEI treated patients. However, none of these differences were significant. Predictably, a higher percentage of patients on ACEI had a history of heart failure (p = 0.03. Age, time-to-imaging or neurological evaluation, risk-factor profile, concomitant therapy with lipid lowering, other antihypertensives or antithrombotic agents, or admission BP were comparable between the two groups. Conclusion Our results

An observational study of implicit motor imagery using laterality recognition of the hand after stroke.

Science.gov (United States)

Amesz, Sarah; Tessari, Alessia; Ottoboni, Giovanni; Marsden, Jon

2016-01-01

To explore the relationship between laterality recognition after stroke and impairments in attention, 3D object rotation and functional ability. Observational cross-sectional study. Acute care teaching hospital. Thirty-two acute and sub-acute people with stroke and 36 healthy, age-matched controls. Laterality recognition, attention and mental rotation of objects. Within the stroke group, the relationship between laterality recognition and functional ability, neglect, hemianopia and dyspraxia were further explored. People with stroke were significantly less accurate (69% vs 80%) and showed delayed reaction times (3.0 vs 1.9 seconds) when determining the laterality of a pictured hand. Deficits either in accuracy or reaction times were seen in 53% of people with stroke. The accuracy of laterality recognition was associated with reduced functional ability (R(2) = 0.21), less accurate mental rotation of objects (R(2) = 0.20) and dyspraxia (p = 0.03). Implicit motor imagery is affected in a significant number of patients after stroke with these deficits related to lesions to the motor networks as well as other deficits seen after stroke. This research provides new insights into how laterality recognition is related to a number of other deficits after stroke, including the mental rotation of 3D objects, attention and dyspraxia. Further research is required to determine if treatment programmes can improve deficits in laterality recognition and impact functional outcomes after stroke.

Organisational change, job strain and increased risk of stroke? A pilot study.

Science.gov (United States)

Medin, Jennie; Ekberg, Kerstin; Nordlund, Anders; Eklund, Jörgen

2008-01-01

The objective of this pilot study was to explore whether organisational change and work-related stress, as measured by the Job Content Questionnaire, were associated with first-ever stroke among working people aged 30-65. In a case-control study a total of 65 consecutive cases, aged 30-65 years of age, with first-ever stroke were recruited from four hospitals in Sweden during 2000-2002. During the same period, 103 random population controls in the same age interval were recruited. Data on job-related stress and traditional medical risk factors were collected by a questionnaire. In the multivariate analyses, organisational change (OR 3.38) increased the likelihood of stroke, while experiencing an active job (OR 0.37) decreased the likelihood of stroke. Regarding risk factors outside work, age (OR 1.11), low physical activity (OR 5.21), low education (OR 2.48) and family history of stroke (OR 2.59) were associated with increased likelihood of stroke. This study suggests an association between organisational change, work-related stress and stroke. The likelihood of stroke was lower for people in active job situations.

Attachment process in rocket-triggered lightning strokes

Science.gov (United States)

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

Small brain lesions and incident stroke and mortality: A cohort study

Science.gov (United States)

Windham, B Gwen; Deere, Bradley; Griswold, Michael E.; Wang, Wanmei; Bezerra, Daniel C; Shibata, Dean; Butler, Kenneth; Knopman, David; Gottesman, Rebecca F; Heiss, Gerardo; Mosley, Thomas H

2015-01-01

Background Although cerebral lesions ≥3mm on imaging are associated with incident stroke, lesions stroke risks associated with subclinical brain lesions by size (stroke; average 14.5 years follow-up. Measurements MRI lesions: none (n=1611), stroke (n=157), overall mortality (n=576), stroke mortality (n=50). Hazard Ratios (HR) estimated with proportional hazards models. Results Compared to no lesions, stroke risk was tripled with lesions Stroke risk doubled with WMH ≥3 (HR=2.14, 95% CI:1.45-3.16). Stroke mortality risk tripled with lesions stroke events (n=147), especially hemorrhagic (n=15); limited numbers of participants with only lesions ≤3mm (n=50) or with both lesions ≤3mm and 3–20mm (n=35). Conclusions Very small cerebrovascular lesions may be associated with increased risks of stroke and mortality; having both < 3 mm and ≥3 mm lesions may represent a particularly striking risk increase. Larger studies are needed to confirm findings and provide more precise estimates. PMID:26148278

Perception of Recurrent Stroke Risk among Black, White and Hispanic Ischemic Stroke and Transient Ischemic Attack Survivors: The SWIFT Study

Science.gov (United States)

Boden-Albala, Bernadette; Carman, Heather; Moran, Megan; Doyle, Margaret; Paik, Myunghee C.

2011-01-01

Objectives Risk modification through behavior change is critical for primary and secondary stroke prevention. Theories of health behavior identify perceived risk as an important component to facilitate behavior change; however, little is known about perceived risk of vascular events among stroke survivors. Methods The SWIFT (Stroke Warning Information and Faster Treatment) study includes a prospective population-based ethnically diverse cohort of ischemic stroke and transient ischemic attack survivors. We investigate the baseline relationship between demographics, health beliefs, and knowledge on risk perception. Regression models examined predictors of inaccurate perception. Results Only 20% accurately estimated risk, 10% of the participants underestimated risk, and 70% of the 817 study participants significantly overestimated their risk for a recurrent stroke. The mean perceived likelihood of recurrent ischemic stroke in the next 10 years was 51 ± 7%. We found no significant differences by race-ethnicity with regard to accurate estimation of risk. Inaccurate estimation of risk was associated with attitudes and beliefs [worry (p risk factors. Conclusion This paper provides a unique perspective on how factors such as belief systems influence risk perception in a diverse population at high stroke risk. There is a need for future research on how risk perception can inform primary and secondary stroke prevention. Copyright © 2011 S. Karger AG, Basel PMID:21894045

Cardiovascular Risk Factors and 5-year Mortality in the Copenhagen Stroke Study

DEFF Research Database (Denmark)

Kammersgaard, Lars Peter; Olsen, Tom Skyhøj

2005-01-01

population. METHODS: We studied 905 ischemic stroke patients from the community-based Copenhagen Stroke Study. Patients had a CT scan and stroke severity was measured by the Scandinavian Stroke Scale on admission. A comprehensive evaluation was performed by a standardized medical examination...... and questionnaire for cardiovascular risk factors, age, and sex. Follow-up was performed 5 years after stroke, and data on mortality were obtained for all, except 6, who had left the country. Five-year mortality was calculated by the Kaplan-Meier procedure and the influence of multiple predictors was analyzed...... by Cox proportional hazards analyses adjusted for age, gender, stroke severity, and risk factor profile. RESULTS: In Kaplan-Meier analyses atrial fibrillation (AF), ischemic heart disease, diabetes, and previous stroke were associated with increased mortality, while smoking and alcohol intake were...

Cardiovascular risk factors and 5-year mortality in the Copenhagen Stroke Study

DEFF Research Database (Denmark)

Kammersgaard, Lars Peter; Olsen, Tom Skyhøj

2005-01-01

population. METHODS: We studied 905 ischemic stroke patients from the community-based Copenhagen Stroke Study. Patients had a CT scan and stroke severity was measured by the Scandinavian Stroke Scale on admission. A comprehensive evaluation was performed by a standardized medical examination...... and questionnaire for cardiovascular risk factors, age, and sex. Follow-up was performed 5 years after stroke, and data on mortality were obtained for all, except 6, who had left the country. Five-year mortality was calculated by the Kaplan-Meier procedure and the influence of multiple predictors was analyzed...... by Cox proportional hazards analyses adjusted for age, gender, stroke severity, and risk factor profile. RESULTS: In Kaplan-Meier analyses atrial fibrillation (AF), ischemic heart disease, diabetes, and previous stroke were associated with increased mortality, while smoking and alcohol intake were...