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1

Turbo-generator control with variable valve actuation  

DOEpatents

An internal combustion engine incorporating a turbo-generator and one or more variably activated exhaust valves. The exhaust valves are adapted to variably release exhaust gases from a combustion cylinder during a combustion cycle to an exhaust system. The turbo-generator is adapted to receive exhaust gases from the exhaust system and rotationally harness energy therefrom to produce electrical power. A controller is adapted to command the exhaust valve to variably open in response to a desired output for the turbo-generator.

Vuk, Carl T. (Denver, IA)

2011-02-22

2

Heart rate variability in soccer players with mitral valve prolapse or benign arrhythmia  

Microsoft Academic Search

Numerous studies have reported increased cardiac vagal activity in well endurance-trained athletes. However, no clear data exist regarding the cardiac autonomic activity in athletes with common cardiovascular findings, such as mild mitral valve prolapse (MVP) and transient benign arrhythmias. Therefore, the purpose of this study was to investigate and compare the cardiac autonomic outflow by heart rate variability (HRV) analysis

N. Koutlianos; E. Kouidi; A. Deligiannis

2004-01-01

3

Pressure variable orifice for hydraulic control valve  

NASA Technical Reports Server (NTRS)

Hydraulic valve absorbs impact energy generated in docking or joining of two large bodies by controlling energy release to avoid jarring shock. The area of exit porting presented to the hydraulic control fluid is directly proportional to the pressure acting on the fluid.

Ammerman, R. L.

1968-01-01

4

Variable percentage exhaust gas recirculation valve  

Microsoft Academic Search

An exhaust gas recirculation (EGR) valve for an internal combustion engine is disclosed in which the rate of flow of exhaust gas from the outlet manifold to the inlet manifold of the engine is controlled as a function of engine load and speed.

1978-01-01

5

Engine having a variable valve actuation system  

DOEpatents

An engine has a cylinder head having a first surface and a second surface spaced from the first surface. A valve is moveably connected to the cylinder head. A rocker arm is connected to the valve, and a rocker shaft having a first location spaced a maximum distance from the cylinder head is connected to the rocker arm. A support member has and an actuator fluid passage network. The actuator fluid passage network defines a volume. The support member is connected to the cylinder head and is positioned such that a majority of the volume of the actuator fluid passage network is between the first location of the rocker shaft and the second surface of the cylinder head.

Hefler, Gregory W. (Chillicothe, IL)

2005-10-12

6

Engine having a variable valve actuation system  

DOEpatents

An engine has a cylinder head having a first surface and a second surface spaced from the first surface. A valve is moveably connected to the cylinder head. A rocker arm is connected to the valve, and a rocker shaft having a first location spaced a maximum distance from the cylinder head is connected to the rocker arm. A support member has and an actuator fluid passage network. The actuator fluid passage network defines a volume. The support member is connected to the cylinder head and is positioned such that a majority of the volume of the actuator fluid passage network is between the first location of the rocker shaft and the second surface of the cylinder head.

Hefler, Gregory W. (Chillicothe, IL)

2004-10-12

7

Advanced Technology Training System on Motor-Operated Valves  

NASA Technical Reports Server (NTRS)

This paper describes how features from the field of Intelligent Tutoring Systems are applied to the Motor-Operated Valve (MOV) Advanced Technology Training System (ATTS). The MOV ATTS is a training system developed at Galaxy Scientific Corporation for the Central Research Institute of Electric Power Industry in Japan and the Electric Power Research Institute in the United States. The MOV ATTS combines traditional computer-based training approaches with system simulation, integrated expert systems, and student and expert modeling. The primary goal of the MOV ATTS is to reduce human errors that occur during MOV overhaul and repair. The MOV ATTS addresses this goal by providing basic operational information of the MOV, simulating MOV operation, providing troubleshooting practice of MOV failures, and tailoring this training to the needs of each individual student. The MOV ATTS integrates multiple expert models (functional and procedural) to provide advice and feedback to students. The integration also provides expert model validation support to developers. Student modeling is supported by two separate student models: one model registers and updates the student's current knowledge of basic MOV information, while another model logs the student's actions and errors during troubleshooting exercises. These two models are used to provide tailored feedback to the student during the MOV course.

Wiederholt, Bradley J.; Widjaja, T. Kiki; Yasutake, Joseph Y.; Isoda, Hachiro

1993-01-01

8

Exhaust gas recirculation control system having variable valve lift correcting speed for exhaust gas recirculation valve  

Microsoft Academic Search

An exhaust gas recirculation control system which is adapted to control the valve opening of the exhaust gas recirculation valve so as to minimize the difference between a detected value of the valve opening of the above value and a command value determined as a function of operating conditions of the engine. The valve opening is corrected at a higher

S. Hasegawa; J. Kimura; T. Koumuta; J. Miyake; T. Nakajima

1984-01-01

9

A novel electromagnetic latching device for variable valve timing in automotive engine  

Microsoft Academic Search

One of the most promising ways to improve fuel economy, reduce CO2 emissions and increase torque output is to achieve variable valve timing (VVT). Some of the devices developed in the past years include mechanical, hydraulic, motor-driven and electromagnetic actuators. Existing most advanced system is an electromagnetic actuator using solenoids to activate engine valves. It, however, needs the current continuously

Jin-Ho Kim; Joung-Hwan Chang; Se-Myung Park; Ki-Il Hwang; Jae-Yong Lee

2010-01-01

10

Investigation of a rotary valving system with variable valve timing for internal combustion engines: Final technical report  

SciTech Connect

The objective of the program was to provide a functional demonstration of the Hansen Rotary Valving System with Variable Valve timing (HRVS/VVT), capable of throttleless inlet charge control, as an alternative to conventional poppet-valves for use in spark ignited internal combustion engines. The goal of this new technology is to secure benefits in fuel economy, broadened torque band, vibration reduction, and overhaul accessibility. Additionally, use of the variable valve timing capability to vary the effective compression ratio is expected to improve multi-fuel tolerance and efficiency. Efforts directed at the design of HRVS components proved to be far more extensive than had been anticipated, ultimately requiring that proof-trial design/development work be performed. Although both time and funds were exhausted before optical or ion-probe types of in-cylinder investigation could be undertaken, a great deal of laboratory data was acquired during the course of the design/development work. This laboratory data is the basis for the information presented in this Final Report.

Cross, P.C.; Hansen, C.N.

1994-11-18

11

Valve  

DOEpatents

A positive acting valve suitable for operation in a corrosive environment is provided. The valve includes a hollow valve body defining an open-ended bore for receiving two, axially aligned, spaced-apart, cylindrical inserts. One insert, designated the seat insert, terminates inside the valve body in an annular face which lies within plane normal to the axis of the two inserts. An elastomeric O-ring seal is disposed in a groove extending about the annular face. The other insert, designated the wedge insert, terminates inside the valve body in at least two surfaces oppositely inclined with respect to each other and with respect to a plane normal to the axis of the two inserts. An elongated reciprocable gate, movable between the two inserts along a path normal to the axis of the two inserts, has a first flat face portion disposed adjacent and parallel to the annular face of the seat insert. The gate has a second face portion opposite to the first face portion provided with at least two oppositely inclined surfaces for mating with respective inclined surfaces of the wedge insert. An opening is provided through the gate which registers with a flow passage through the two inserts when the valve is open. Interaction of the respective inclined surfaces of the gate and wedge insert act to force the first flat face portion of the gate against the O-ring seal in the seat insert at the limits of gate displacement where it reaches its respective fully open and fully closed positions.

Cho, Nakwon (Knoxville, TN)

1980-01-01

12

Internal combustion engine with rotary valve assembly having variable intake valve timing  

DOEpatents

An internal combustion engine has rotary valves associated with movable shutters operable to vary the closing of intake air/fuel port sections to obtain peak volumetric efficiency over the entire range of speed of the engine. The shutters are moved automatically by a control mechanism that is responsive to the RPM of the engine. A foot-operated lever associated with the control mechanism is also used to move the shutters between their open and closed positions.

Hansen, Craig N. (Eden Prairie, MN); Cross, Paul C. (Shorewood, MN)

1995-01-01

13

Effect Analysis of Design Variables on the Disc in a Double-Eccentric Butterfly Valve  

PubMed Central

We have performed a shape optimization of the disc in an industrial double-eccentric butterfly valve using the effect analysis of design variables to enhance the valve performance. For the optimization, we select three performance quantities such as pressure drop, maximum stress, and mass (weight) as the responses and three dimensions regarding the disc shape as the design variables. Subsequently, we compose a layout of orthogonal array (L16) by performing numerical simulations on the flow and structure using a commercial package, ANSYS v13.0, and then make an effect analysis of the design variables on the responses using the design of experiments. Finally, we formulate a multiobjective function consisting of the three responses and then propose an optimal combination of the design variables to maximize the valve performance. Simulation results show that the disc thickness makes the most significant effect on the performance and the optimal design provides better performance than the initial design. PMID:24883380

Kim, Da-Eun; Kim, Kuk-Kyeom; Kim, Jun-Oh

2014-01-01

14

Working Characteristics of Variable Intake Valve in Compressed Air Engine  

PubMed Central

A new camless compressed air engine is proposed, which can make the compressed air energy reasonably distributed. Through analysis of the camless compressed air engine, a mathematical model of the working processes was set up. Using the software MATLAB/Simulink for simulation, the pressure, temperature, and air mass of the cylinder were obtained. In order to verify the accuracy of the mathematical model, the experiments were conducted. Moreover, performance analysis was introduced to design compressed air engine. Results show that, firstly, the simulation results have good consistency with the experimental results. Secondly, under different intake pressures, the highest output power is obtained when the crank speed reaches 500?rpm, which also provides the maximum output torque. Finally, higher energy utilization efficiency can be obtained at the lower speed, intake pressure, and valve duration angle. This research can refer to the design of the camless valve of compressed air engine. PMID:25379536

Yu, Qihui; Shi, Yan; Cai, Maolin

2014-01-01

15

Variable compliance device for a respiratory physiotherapy training simulator  

E-print Network

Variable compliance device for a respiratory physiotherapy training simulator Tobias Büssing for physiotherapists training. A simulator, designed to behave like an infant thorax, for respiratory physiotherapy

Paris-Sud XI, Université de

16

Motion planning for experimental air path control of a variable-valve-timing spark ignition engine  

E-print Network

Motion planning for experimental air path control of a variable-valve-timing spark ignition engine Syste´mes, Mines-ParisTech 60, bd St Michel, 75272 Paris, France a r t i c l e i n f o Article history using a FAR measurement (given by an oxygen sensor situated at the engine exhaust), which

17

Percutaneous balloon dilatation of the mitral valve: an analysis of echocardiographic variables related to outcome and the mechanism of dilatation.  

PubMed Central

Twenty two patients (four men, 18 women, mean age 56 years, range 21 to 88 years) with a history of rheumatic mitral stenosis were studied by cross sectional echocardiography before and after balloon dilatation of the mitral valve. The appearance of the mitral valve on the pre-dilatation echocardiogram was scored for leaflet mobility, leaflet thickening, subvalvar thickening, and calcification. Mitral valve area, left atrial volume, transmitral pressure difference, pulmonary artery pressure, cardiac output, cardiac rhythm, New York Heart Association functional class, age, and sex were also studied. Because there was some increase in valve area in almost all patients the results were classified as optimal or suboptimal (final valve area less than 1.0 cm2, final left atrial pressure greater than 10 mm Hg, or final valve area less than 25% greater than the initial area). The best multiple logistic regression fit was found with the total echocardiographic score alone. A high score (advanced leaflet deformity) was associated with a suboptimal outcome while a low score (a mobile valve with limited thickening) was associated with an optimal outcome. No other haemodynamic or clinical variables emerged as predictors of outcome in this analysis. Examination of pre-dilatation and post-dilatation echocardiograms showed that balloon dilatation reliably resulted in cleavage of the commissural plane and thus an increase in valve area. Images Fig 1 Fig 2 Fig 3 Fig 4 Fig 6 PMID:3190958

Wilkins, G T; Weyman, A E; Abascal, V M; Block, P C; Palacios, I F

1988-01-01

18

Blood Pressure Variability and Stress Management Training for Essential Hypertension  

ERIC Educational Resources Information Center

The purpose of this study was to determine whether stress management training reduces blood pressure (BP) variability in hypertensive patients. Previous literature suggests that cardiovascular risk is not only a function of BP levels, but also of BP variability, and this partially depends on changes induced by the stress of everyday life. The

Garcia-Vera, Maria Paz; Sanz, Jesus; Labrador, Francisco J.

2004-01-01

19

Development of a variable quench pressure relief valve for superconducting magnet system  

NASA Astrophysics Data System (ADS)

A new variable quench pressure relief valve (VQRV) for a superconducting magnet system has been developed at the High Energy Accelerator Research Organization (KEK). The VQRV is designed that the setting of the blowout pressure can be freely controlled and be maintenance-free for long-term operation. A prototype VQRV was tested under a high radiation environment up to 2.5 MGy. The heat load of 1.5 W at 4.2 K and a seat leakage rate of 4.5 10 -7 kg/s at 4.2 K of the VQRV were confirmed. It has enough performances for the cryogenic system operation in the Japan Proton Accelerator Research Complex (J-PARC) neutrino beam line. The design and test results of the VQRV are described in this technical note.

Kimura, N.; Ohhata, H.; Okamura, T.; Makida, Y.; Yoshida, H.

2011-08-01

20

Limit-push training reduces motor variability  

Microsoft Academic Search

Variability in human motor control has been a long observed phenomenon, which has come to be known by some as repetition without repetition. There are several explanations for this. One such explanation asserts that many equally optimal solutions exist for accomplishing the same task that naturally allows choices in how it can be successfully executed. The aim of this study

Ian Sharp; James L. Patton

2011-01-01

21

Combustion Phasing Model for Control of a Gasoline-Ethanol Fueled SI Engine with Variable Valve Timing  

E-print Network

Combustion Phasing Model for Control of a Gasoline-Ethanol Fueled SI Engine with Variable Valve engine efficiency. Fuel-flexible engines permit the increased use of ethanol-gasoline blends. Ethanol points across the engine operating range for four blends of gasoline and ethanol. I. INTRODUCTION Fuel

22

Resistance Training for the Older Adult: Manipulating Training Variables to Enhance Muscle Strength  

Microsoft Academic Search

Resistance training has been shown to reliably and substantially enhance muscle function in older adults and these improvements can be accompanied by improved functional perrformance. Training variables should be manipulated to enhance muscle strength and minimize injury risks in the population.

Daniel A. Galvo; Dennis R. Taaffe

2005-01-01

23

Addressing Cultural Variables in Parent Training Programs with Latino Families  

ERIC Educational Resources Information Center

There has recently been increased attention given to understanding how cultural variables may have an impact on the efficacy of treatments with Latino families seeking psychological services. Within parent training programs, understanding the extent to which culture can affect parenting practices is vital to providing quality care. The focus of

Barker, Chikira H.; Cook, Katrina L.; Borrego, Joaquin, Jr.

2010-01-01

24

Multirate closed-loop system identification of a variable valve timing actuator for an internal combustion engine  

Microsoft Academic Search

This paper applies the multi-rate closed-loop system identification (ID) technique to a continuously variable valve timing (VVT) actuator system. Limited by the sample rate of the crank-based cam position sensor, function of engine speed, the actuator control sample rate is different from that of cam position sensor. Multi-rate system identification is a necessity for this application. On the other hand,

Zhen Ren; Guoming G. Zhu

2010-01-01

25

Heart rate variability is related to training load variables in interval running exercises  

Microsoft Academic Search

Overload principle of training states that training load (TL) must be sufficient to threaten the homeostasis of cells, tissues,\\u000a organs and\\/or body. However, there is no golden standard for TL measurement. The aim of the present study was to investigate\\u000a if post-exercise heart rate variability (HRV) could be used to evaluate TL of interval running exercises with different intensities\\u000a and

Piia Kaikkonen; Esa Hynynen; Theresa Mann; Heikki Rusko; Ari Nummela

26

Hydraulic damper for vehicles with variable orifice piston valving for varying damping force  

SciTech Connect

A hydraulic damping unit is described for controlling the spring action of vehicle suspension springs comprising a cylinder tube having a hydraulic fluid therein, a valved piston having a generally cylindrical body mounted for linear stroking movement in the cylinder tube and hydraulically separating the cylinder tube into first and second chambers, valve means within the body of the piston for controlling the flow of hydraulic fluid between the chambers through the piston, a piston rod connected directly to the body of the piston and extending to the exterior of the damping unit, a rotatable actuator operatively mounted in the piston rod. The valve means consists of an orifice plate fixed within the body of the piston having a plurality of hydraulic fluid flow controlling orifices therethrough, first and second deflectable spring disk means mounted on opposite sides of the orifice plate operatively associated with the orifices providing primary control of the damping force of the unit, fastener means extending through the orifice plate and the first and second disk means within the body of the piston, separate and varying size fluid flow passages extended through the fastener means in parallel with the orifices. The fastener means a head portion within the body of the piston, a selector plate rotatably mounted on the head portion and having a selector opening therein selectively registrable with any of the passages, means operatively connecting the selector plate to the actuator for rotation thereby so that any of the fluid flow passages can be selected for varying the damping action of the unit.

Fannin, W.V.; Buchanan, H.C. Jr.

1987-08-11

27

Analysis and Simulation of Mechanical Trains Driven by Variable Frequency Drive Systems  

E-print Network

Induction motors and Variable Frequency Drives (VFDs) are widely used in industry to drive machinery trains. However, some mechanical trains driven by VFD-motor systems have encountered torsional vibration problems. This vibration can induce large...

Han, Xu

2012-02-14

28

Testing the Impact of Job-Related Variables on a Utility Judgment Training Criterion beyond Background and Affective Reaction Variables  

ERIC Educational Resources Information Center

We tested the incremental impact of a job-related set of variables for explaining a utility judgment training effectiveness variable, that is, course completion skill preparedness, beyond background and course-related variables. Our respondents were two different emergency medical service samples, 415 basics and 742 paramedics, from the 2008 US

Blau, Gary; Gibson, Greg; Bentley, Melissa; Chapman, Susan

2012-01-01

29

Spray characterization of flex-fuel gasoline DI injectors and spray interaction with charge motion in a variable valve actuation engine  

Microsoft Academic Search

The objective of this study is to understand the characteristics of GDI sprays and behavior of in-cylinder charge motion in a GDI engine which is equipped with variable valve actuation. High speed spray visualization in a spray chamber was conducted for a study of spray development. By Schlieren visualization technique, the effect of different conditions including ambient conditions (temperature, pressure)

Atsushi Matsumoto

2012-01-01

30

Spray characterization of flex-fuel gasoline di injectors and spray interaction with charge motion in a variable valve actuation engine  

Microsoft Academic Search

The objective of this study is to understand the characteristics of GDI sprays and behavior of in-cylinder charge motion in a GDI engine which is equipped with variable valve actuation. High speed spray visualization in a spray chamber was conducted for a study of spray development. By Schlieren visualization technique, the effect of different conditions including ambient conditions (temperature, pressure)

Atsushi Matsumoto

2012-01-01

31

Aortic valve replacement: is porcine or bovine valve better?  

PubMed

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was: 'Is porcine or bovine valve better for aortic valve replacement?' Altogether, 562 papers were found using the reported search, of which 15 represented the best evidence to answer the question. All papers represent either level 1 or 2 evidence. The authors, journal, date, country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. This best evidence paper includes 9880 patients from 1974-2006 to compare both valve types. All studies compared either all or some of the following outcomes: complication, durability, mortality, functional status and haemodynamic function. Ten of 15 papers assessed the complication profile due to aortic valve replacement in both valve types. Four papers concluded that bovine valves are superior, whereas only one favoured porcine valves. Five papers showed a similar complication profile between both valves. Six of 15 papers commented on valve durability. Both porcine and bovine valve groups have two papers each to support their superiority in valve durability. Two papers demonstrated similar durability in both valves. There are 11 papers comparing the postoperative mortality. We suggest that there is no difference in mortality profile as eight papers showed that both valves had similar mortality profiles. Two papers supported bovine valve and one paper supported porcine valve in this aspect. There were four papers assessing the postoperative functional status, with three papers suggesting that both valve types had similar clinical improvement postoperatively. Eleven papers compared the haemodynamic function. Nine papers were in favour of bovine valves. Two papers demonstrated similar haemodynamic profiles in both valves. In conclusion, the bovine valve is superior in its complication and haemodynamic profiles. Both bovine and porcine valves have comparable results with regard to the mortality, postoperative functional status and valve durability. Significant variability between the valve manufacturers, study designs, study period and patient population in the above studies impose limitations to the comparison of both valves. PMID:23211215

Yap, Kok Hooi; Murphy, Ralph; Devbhandari, Mohan; Venkateswaran, Rajamiyer

2013-03-01

32

Training of fuzzy inference systems by combining variable structure systems technique and Levenberg-Marquardt algorithm  

Microsoft Academic Search

This paper presents a novel training algorithm for fuzzy inference systems. The algorithm combines the Levenberg-Marquardt algorithm with variable structure systems approach. The combination is performed by expressing the parameter update rule in continuous time and application of sliding control method to the gradient based training procedure. In this paper, a fuzzy inference mechanism that can be trained such that

M. Onder Efe; Okyay Kaynak; Bogdan M. Wilamowski

1999-01-01

33

Safety valve  

DOEpatents

The safety valve contains a resilient gland to be held between a valve seat and a valve member and is secured to the valve member by a sleeve surrounding the end of the valve member adjacent to the valve seat. The sleeve is movable relative to the valve member through a limited axial distance and a gap exists between said valve member and said sleeve.

Bergman, Ulf C. (Malmoe, SE)

1984-01-01

34

Isotope measurements of single ostracod valves and gastropod shells for climate reconstruction: evaluation of within-sample variability and determination of optimum sample size  

Microsoft Academic Search

Sediment cores from Lakes Punta Laguna, Chichancanab, and Petn Itz on the Yucatan Peninsula were used to (1) investigate\\u000a within-horizon stable isotope variability (?18O and ?13C) measured on multiple, single ostracod valves and gastropod shells, (2) determine the optimum number of individuals required\\u000a to infer low-frequency climate changes, and (3) evaluate the potential for using intra-sample ?18O variability in ostracod

Jaime Escobar; Jason H. Curtis; Mark Brenner; David A. Hodell; Jonathan A. Holmes

2010-01-01

35

Effect of long term physical training on heart rate variability  

Microsoft Academic Search

The purpose of this study was to investigate the influence of physical training on the autonomic nervous system in healthy subjects. The authors compared 28 trained athletes and 28 sedentary subjects and divided them into two age groups: 18 to 34 and 35 to 55 years of age. ECG was recorded during 2 minutes while the subjects were breathing periodically

A. E. Aubert; D. Ramaekers; Y. Cuche; R. Lysens; H. Ector; F. Van de Werf

1996-01-01

36

Virtual humans for inter-ethnic variability training in sedation and analgesia.  

PubMed

The objective of this research is to enable realistic Virtual Humans (VH) that support inter-ethnic variability training. Inter-ethnic variability refers to differences in response to medical treatment, such as drug administration, due to ethnicity (e.g., Caucasian, African American, or South Asian). Most current approaches to VHs do not model these differences. Our approach consists of driving VH responses based on a real time pharmacodynamic / pharmacokinetic propofol model that includes inter-ethnic variability. Results of a user study with 22 medical students suggest that utilizing VHs for inter-ethnic variability training is feasible and can increase awareness of inter-ethnic variability. PMID:24732502

Jendrusch, Jason; Lampotang, Samsun; Lizdas, David; Gravenstein, Nikolaus; Ham, Dwayne; Lok, Benjamin; Quarles, John

2014-01-01

37

Percutaneous balloon dilatation of the mitral valve: an analysis of echocardiographic variables related to outcome and the mechanism of dilatation  

Microsoft Academic Search

Twenty two patients (four men, 18 women, mean age 56 years, range 21 to 88 years) with a history of rheumatic mitral stenosis were studied by cross sectional echocardiography before and after balloon dilatation of the mitral valve. The appearance of the mitral valve on the pre-dilatation echocardiogram was scored for leaflet mobility, leaflet thickening, subvalvar thickening, and calcification. Mitral

G T Wilkins; A E Weyman; V M Abascal; P C Block; I F Palacios

1988-01-01

38

Polarized training has greater impact on key endurance variables than threshold, high intensity, or high volume training  

PubMed Central

Endurance athletes integrate four conditioning concepts in their training programs: high-volume training (HVT), threshold-training (THR), high-intensity interval training (HIIT) and a combination of these aforementioned concepts known as polarized training (POL). The purpose of this study was to explore which of these four training concepts provides the greatest response on key components of endurance performance in well-trained endurance athletes. Methods: Forty eight runners, cyclists, triathletes, and cross-country skiers (peak oxygen uptake: (VO2peak): 62.6 7.1 mLmin?1kg?1) were randomly assigned to one of four groups performing over 9 weeks. An incremental test, work economy and a VO2peak tests were performed. Training intensity was heart rate controlled. Results: POL demonstrated the greatest increase in VO2peak (+6.8 mlminkg?1 or 11.7%, P < 0.001), time to exhaustion during the ramp protocol (+17.4%, P < 0.001) and peak velocity/power (+5.1%, P < 0.01). Velocity/power at 4 mmolL?1 increased after POL (+8.1%, P < 0.01) and HIIT (+5.6%, P < 0.05). No differences in pre- to post-changes of work economy were found between the groups. Body mass was reduced by 3.7% (P < 0.001) following HIIT, with no changes in the other groups. With the exception of slight improvements in work economy in THR, both HVT and THR had no further effects on measured variables of endurance performance (P > 0.05). Conclusion: POL resulted in the greatest improvements in most key variables of endurance performance in well-trained endurance athletes. THR or HVT did not lead to further improvements in performance related variables. PMID:24550842

Stoggl, Thomas; Sperlich, Billy

2014-01-01

39

Exercise Training in Athletes with Bicuspid Aortic Valve Does Not Result in Increased Dimensions and Impaired Performance of the Left Ventricle  

PubMed Central

Background. Bicuspid aortic valve (BAV) is one of the most common congenital heart disease (0.9%2%) and is frequently found in the athletes and in the general population. BAV can lead to aortic valve dysfunction and to a progressive aortic dilatation. Trained BAV athletes exhibit a progressive enlargement of the left ventricle (LV) compared to athletes with normal aortic valve morphology. The present study investigates the possible relationship between different aortic valve morphology and LV dimensions. Methods. In the period from 2000 to 2011, we investigated a total of 292 BAV subjects, divided into three different groups (210 athletes, 59 sedentaries, and 23 ex-athletes). A 2D echocardiogram exam to classify BAV morphology and measure the standard LV systo-diastolic parameters was performed. The study was conducted as a 5-year follow-up echocardiographic longitudinal and as cross-sectional study. Results. Typical BAV was more frequent in all three groups (68% athletes, 67% sedentaries, and 63% ex-athletes) than atypical. In BAV athletes, the typical form was found in 51% (107/210) of soccer players, 10% (21/210) of basketball players, 10% track and field athletics (20/210), 8% (17/210) of cyclists, 6% (13/210) swimmers, and 15% (32/210) of rugby players and others sport. Despite a progressive enlargement of the LV (P < 0.001) observed during the follow-up study, no statistical differences of the LV morphology and function were evident among the diverse BAV patterns either in sedentary subjects or in athletes. Conclusion. In a large population of trained BAV athletes, with different prevalence of typical and atypical BAV type, there is a progressive nonstatistically significant enlargement of the LV. In any case, the dimensions of the LV remained within normal range. The metabolic requirements of the diverse sport examined in the present investigations do not seem to produce any negative impact in BAV athletes PMID:24600528

Stefani, Laura; Galanti, Giorgio; Innocenti, Gabriele; Mercuri, Roberto; Maffulli, Nicola

2014-01-01

40

Effects of dynamic resistance training on heart rate variability in healthy older women  

Microsoft Academic Search

\\u000a Twenty healthy women aged between 65 and 74years, trained three times a week, for 16weeks, on a cycle ergometer, to determine\\u000a the effects of dynamic resistance training on heart rate variability (HRV). Subjects were allocated to two training groups,\\u000a high (HI, n=10) and low (LO, n=10) intensity. The HI group performed eight sets of 8revolutions at 80% of the

Roberta Forte; Giuseppe De Vito; Francesco Figura

2003-01-01

41

Quantitative Poincar plot analysis of heart rate variability: effect of endurance training  

Microsoft Academic Search

The aim of the study was to evaluate the effectiveness of the Poincar plot analysis of heart rate variability (HRV) in observing endurance training-induced changes. Four 10-min manoeuvres were performed (supine lying, standing, steady state exercising and subsequent recovery) by eight control subjects before and after a short-term endurance training and by eight subjects trained for at least 3years. HRV

Laurent Mourot; Malika Bouhaddi; Stphane Perrey; Jean-Denis Rouillon; Jacques Regnard

2004-01-01

42

Fault detection of an engine using a neural network trained by the smooth variable structure filter  

Microsoft Academic Search

A multilayered neural network is a multi-input, multi-output (MIMO) nonlinear system in which training can be regarded as a nonlinear parameter estimation problem by estimating the network weights. In this paper, the relatively new smooth variable structure filter (SVSF) is used for the training of a nonlinear multilayered feed forward network. The SVSF is a recursive sliding mode parameter and

Ryan M. Ahmed; Mohammed A. El Sayed; S. Andrew Gadsden; Saeid R. Habibi

2011-01-01

43

Central hemodynamic and heart rate variability parameters in athletes during different training programs  

Microsoft Academic Search

Central hemodynamic and heart rate variability (HRV) parameters were assessed in highly qualified athletes differing in the\\u000a types of their training programs at relative rest. During endurance (the endurance group, n = 27) and strength (the strength group, n = 17) trainings, the total peripheral resistance (TPR) was decreased by 15% (p = 0.003) in the endurance group and by

A. Yu. Maltsev; A. A. Melnikov; A. D. Vikulov; K. S. Gromova

2010-01-01

44

Reliability and variability of day-to-day vault training measures in artistic gymnastics  

Microsoft Academic Search

Inter-day training reliability and variability in artistic gymnastics vaulting was determined using a customised infra-red timing gate and contact mat timing system. Thirteen Australian high performance gymnasts (eight males and five females) aged 1123 years were assessed during two consecutive days of normal training. Each gymnast completed a number of vault repetitions per daily session. Inter-day variability of vault run-up

Elizabeth Bradshaw; Patria Hume; Mark Calton; Brad Aisbett

2010-01-01

45

Anthropometric and training variables related to 10km running performance.  

PubMed Central

Sixty male distance athletes were divided into three equal groups according to their personal best time for the 10km run. The runners were measured anthropometrically and each runner completed a detailed questionnaire on his athletic status, training programme and performance. The runners in this study had similar anthropometric and training profiles to other distance runners of a similar standard. The most able runners were shorter and lighter than those in the other two groups and significantly smaller skinfold values (P less than 0.05). There were no significant differences between the groups for either bone widths or circumferences but the elite and good runners had significantly higher ponderal indices (P less than 0.05) than the average runners, indicating that they are more linear. Elite and good runners were also less endomorphic but more ectomorphic than the average runners. The elite runners trained more often, ran more miles per week and had been running longer (P less than 0.05) than good or average runners. A multiple regression and discriminant function analysis indicated that linearity, total skinfold, the type and frequency of training and the number of years running were the best predictors of running performance and success at the 10km distance. PMID:3814989

Bale, P; Bradbury, D; Colley, E

1986-01-01

46

THE INFLUENCE OF TRAINING ON HEART RATE VARIABILITY IN HEALTHY OLDER ADULTS  

Microsoft Academic Search

The effect of one-year physical training on heart rate variability in older adults was evaluated in 14 healthy men (age > 55 year). Measures of heart rate variability were obtained in both time and frequency domain. Ten- minute ECG recordings were made in supine position and in standing position. A progressive climbing exertion test till exhaustion was performed to estimate

B. Seps; F. Beckers; D. Ramaekers; A. E. Aubert

2001-01-01

47

Increasing Response Variability of Mand Frames with Script Training and Extinction  

ERIC Educational Resources Information Center

Children with autism often demonstrate less variable behavior than their typically developing peers and those with other cognitive disabilities. A possible reason for lack of response variability emitted by children with autism is that they do not have a variety of response forms in their repertoire. Multiple-exemplar training through the use of

Betz, Alison M.; Higbee, Thomas S.; Kelley, Kristen N.; Sellers, Tyra P.; Pollard, Joy S.

2011-01-01

48

Aortic Valve  

MedlinePLUS

... in this category include " xenograft " valves made from animal tissues (most often pig aortic valves), " homograft " or " allograft " valves retrieved from human cadavers, and " pulmonary autograft " valves moved from the patient's pulmonary artery on the right side of the heart to the aortic position ...

49

Plug valve  

DOEpatents

An improved plug valve wherein a novel shape for the valve plug and valve chamber provide mating surfaces for improved wear characteristics. The novel shape of the valve plug is a frustum of a body of revolution of a curved known as a tractrix, a solid shape otherwise known as a peudosphere.

Wordin, John J. (Shelley, ID)

1989-01-01

50

Promoting Response Variability and Stimulus Generalization in Martial Arts Training  

ERIC Educational Resources Information Center

The effects of reinforcement and extinction on response variability and stimulus generalization in the punching and kicking techniques of 2 martial arts students were evaluated across drill and sparring conditions. During both conditions, the students were asked to demonstrate different techniques in response to an instructor's punching attack.

Harding, Jay W.; Wacker, David P.; Berg, Wendy K.; Rick, Gary; Lee, John F.

2004-01-01

51

Supercharged two-cycle engines employing novel single element reciprocating shuttle inlet valve mechanisms and with a variable compression ratio  

NASA Technical Reports Server (NTRS)

This invention relates to novel reciprocating shuttle inlet valves, effective with every type of two-cycle engine, from small high-speed single cylinder model engines, to large low-speed multiple cylinder engines, employing spark or compression ignition. Also permitting the elimination of out-of-phase piston arrangements to control scavenging and supercharging of opposed-piston engines. The reciprocating shuttle inlet valve (32) and its operating mechanism (34) is constructed as a single and simple uncomplicated member, in combination with the lost-motion abutments, (46) and (48), formed in a piston skirt, obviating the need for any complex mechanisms or auxiliary drives, unaffected by heat, friction, wear or inertial forces. The reciprocating shuttle inlet valve retains the simplicity and advantages of two-cycle engines, while permitting an increase in volumetric efficiency and performance, thereby increasing the range of usefulness of two-cycle engines into many areas that are now dominated by the four-cycle engine.

Wiesen, Bernard (Inventor)

2008-01-01

52

Differences in Acceleration Training and Exercise Training on Resting Cardiovascular Variables  

NASA Technical Reports Server (NTRS)

The relative effects of alternating exercise vs. acclamation training an mean blood pressure (BP, Finapres), cardiac output (CO, BoMed) and peripheral resistance (PR, calculated) were evaluated. Six healthy men (33$\\pm$(SD)6 yr. 178$\\pm$4 cm, 86$\\pm$6 kg) underwent exercise training (ET, n=3): supine on a cycle ergometer (40 to 90\\% Vo$_{2}$ max) during exposure to constant+1G$_{z}$ for $\\sim$30 min/day for 14 days on NASA's 1.9m Human Powered Centrifuge (HPC). They also underwent oscillatory (between +1 G$ {z}$and$\\sim$2.5G$_{z}$) acceleration training (AT, n=3) for $\\sim$30 min/day for 14 days on the HPC. After four weeks of ambulatory deconditioning, training protocols were switched. AT increased resting CO by 9.MpmS(SE)3.2\\% (p$less than$0.05) with no effect on BF, and ET decreased BP by 9.2$\\pm$4.6\\% (p$less than$0.08) as well as spectral power of PR by 41$\\pm$9\\% (p$less than$0.05). The major effect of acceleration training was to increase resting cardiac output while that of exercise mining was to decrease resting blood pressure.

Evans, J. M.; Simonson, S. R.; Knapp, C. F.; Stocks, J. M.; Biagini, H. W.; Cowell, S. A.; Bailey, Kn. N.; Vener, J. M.; Evetts, S. N.; Dalton, Bonnie P. (Technical Monitor)

2000-01-01

53

Effect of high intensity intermittent training on heart rate variability in prepubescent children  

Microsoft Academic Search

The purpose of this study was to observe the effect of high intermittent exercise training on childrens heart rate variability\\u000a (HRV). Thirty-eight children (age 9.61.2years) were divided into an intermittent (IT, n=22) and a control group (CON, n=16). At baseline and after a 7-week training period, HRV parameters, peak oxygen consumption $$ (\\\\dot{V}{\\\\text{O}}_{{2{\\\\text{peak}}}} ) $$ and maximal aerobic velocity (MAV)

Franois-Xavier Gamelin; Georges Baquet; Serge Berthoin; Delphine Thevenet; Cedric Nourry; Stphane Nottin; Laurent Bosquet

2009-01-01

54

Check valve  

DOEpatents

A check valve for use in a GDCS of a nuclear reactor and having a motor driven disk including a rotatable armature for rotating the check valve disk over its entire range of motion is described. In one embodiment, the check valve includes a valve body having a coolant flow channel extending therethrough. The coolant flow channel includes an inlet end and an outlet end. A valve body seat is located on an inner surface of the valve body. The check valve further includes a disk assembly, sometimes referred to as the motor driven disc, having a counterweight and a disk shaped valve. The disk valve includes a disk base having a seat for seating with the valve body seat. The disk assembly further includes a first hinge pin member which extends at least partially through the disk assembly and is engaged to the disk. The disk valve is rotatable relative to the first hinge pin member. The check valve also includes a motor having a stator frame with a stator bore therein. An armature is rotatably positioned within the stator bore and the armature is coupled to the disk valve to cause the disk valve to rotate about its full range of motion. 5 figs.

Upton, H.A.; Garcia, P.

1999-08-24

55

Check valve  

DOEpatents

A check valve for use in a GDCS of a nuclear reactor and having a motor driven disk including a rotatable armature for rotating the check valve disk over its entire range of motion is described. In one embodiment, the check valve includes a valve body having a coolant flow channel extending therethrough. The coolant flow channel includes an inlet end and an outlet end. A valve body seat is located on an inner surface of the valve body. The check valve further includes a disk assembly, sometimes referred to as the motor driven disc, having a counterweight and a disk shaped valve. The disk valve includes a disk base having a seat for seating with the valve body seat. The disk assembly further includes a first hinge pin member which extends at least partially through the disk assembly and is engaged to the disk. The disk valve is rotatable relative to the first hinge pin member. The check valve also includes a motor having a stator frame with a stator bore therein. An armature is rotatably positioned within the stator bore and the armature is coupled to the disk valve to cause the disk valve to rotate about its full range of motion.

Upton, Hubert Allen (Morgan Hill, CA); Garcia, Pablo (Stanford, CA)

1999-08-24

56

Effects of different training amplitudes on heart rate and heart rate variability in young rowers.  

PubMed

Vaz, MS, Picano, LM, and Del Vecchio, FB. Effects of different training amplitudes on heart rate and heart rate variability in young rowers. J Strength Cond Res 28(10): 2967-2972, 2014-The aim of this study was to investigate the autonomic nervous system recovery and the psychological response as a result of 3 training amplitudes on heart rate (HR), heart rate variability (HRV), and rate of perceived exertion (RPE) in rowing. Eight young rowers (16.8 1.4 years) performed, in a randomized fashion, 2 sessions of high-intensity interval training, with high and low amplitude and a continuous training (CT) session, with the same exercise duration (10 minutes) and mean intensity (60% of maximal stroke test). The data of HR, HRV, and RPE were collected 5 minutes before, immediately after each session, and 24 hours later. High amplitude promoted higher impact in maximum HR (p ? 0.05) and RPE (p < 0.001) when compared with CT. For the time domain HRV variable, there was a statistically significant difference between moments of rest (pretraining or post 24 hours) and posttraining in all training sessions. Originally, we conclude that training with higher load variation between effort and recovery impacts HRV, HR, and RPE with greater intensity, but the younger rowers were ready for new training sessions 24 hours after either training method. Coaches can use the polarized training method, observing the stimulus nature and time required for recovery, because it may be an adequate strategy for the development of rower's conditioning. PMID:24736775

Vaz, Marcelo S; Picano, Luan M; Del Vecchio, Fabrcio B

2014-10-01

57

Association between heart rate variability and training response in sedentary middle-aged men  

Microsoft Academic Search

The effect of exercise training on heart rate variability (HRV) and improvements in peak oxygen consumption (\\u000a$$\\\\dot V{\\\\text{O}}_{\\\\text{2}} $$\\u000a\\u000apeak) was examined in sedentary middle-aged men. The HRV and absolute and relative\\u000a$$\\\\dot V{\\\\text{O}}_{\\\\text{2}} $$\\u000a\\u000apeak of training (n = 19) and control (n = 15) subjects were assessed before and after a 24-session moderate intensity exercise training programme.

Stephen H. Boutcher; Phyllis Stein

1995-01-01

58

Prediction of space sickness in astronauts from preflight fluid, electrolyte, and cardiovascular variables and Weightless Environmental Training Facility (WETF) training  

NASA Technical Reports Server (NTRS)

Nine preflight variables related to fluid, electrolyte, and cardiovascular status from 64 first-time Shuttle crewmembers were differentially weighted by discrimination analysis to predict the incidence and severity of each crewmember's space sickness as rated by NASA flight surgeons. The nine variables are serum uric acid, red cell count, environmental temperature at the launch site, serum phosphate, urine osmolality, serum thyroxine, sitting systolic blood pressure, calculated blood volume, and serum chloride. Using two methods of cross-validation on the original samples (jackknife and a stratefied random subsample), these variables enable the prediction of space sickness incidence (NONE or SICK) with 80 percent sickness and space severity (NONE, MILD, MODERATE, of SEVERE) with 59 percent success by one method of cross-validation and 67 percent by another method. Addition of a tenth variable, hours spent in the Weightlessness Environment Training Facility (WETF) did not improve the prediction of space sickness incidences but did improve the prediction of space sickness severity to 66 percent success by the first method of cross-validation of original samples and to 71 percent by the second method. Results to date suggest the presence of predisposing physiologic factors to space sickness that implicate fluid shift etiology. The data also suggest that prior exposure to fluid shift during WETF training may produce some circulatory pre-adaption to fluid shifts in weightlessness that results in a reduction of space sickness severity.

Simanonok, K.; Mosely, E.; Charles, J.

1992-01-01

59

Variability in the response of HDL cholesterol to exercise training in the HERITAGE Family Study.  

PubMed

In the HERITAGE Family Study, 675 sedentary, healthy, white and black men and women, aged 17 to 65 years, performed 20 weeks of supervised cycle ergometer exercise at the same relative intensity and weekly volume. As a group, subjects had normal mean baseline lipid levels for North Americans with the exception of below average high density lipoprotein cholesterol (HDL-C) levels. A significant mean increase in plasma HDL-C of 3.6 % was observed; however, there was marked variability in responsiveness to training, ranging from a mean 9.3 % decrease in Quartile 1 of HDL-C response to a mean 18 % increase in Quartile 4 (P < 0.0001 by ANOVA). Parallel changes in HDL(2)-C and HDL(3)-C, apolipoprotein A-I levels, and lipoprotein lipase activity were noted across quartiles. The change in HDL-C across quartiles was inversely related to baseline HDL-C (p < 0.0001) and to changes with training in plasma triglycerides (p = 0.0007). No significant differences in HDL-C response were observed across quartiles by sex, race, age, or increase in VO(2)max with training; however, weak positive associations were observed with age-adjusted education level and with reduction in abdominal fat and increase in VO(2)max at the ventilatory threshold following training. Multivariate regression analysis including baseline variables and training responses only accounted for 15.5 % of the variability in the HDL-C response to training. Thus, marked variability was found in the HDL-C response to the same endurance exercise training stimulus with only a modest amount of the response predictable by identified nongenetic factors. PMID:11774059

Leon, A S; Gaskill, S E; Rice, T; Bergeron, J; Gagnon, J; Rao, D C; Skinner, J S; Wilmore, J H; Bouchard, C

2002-01-01

60

Variable-cam resistance training machines: Do they match the angletorque relationship in humans?  

Microsoft Academic Search

The aim of this study was to determine the extent to which the resistance provided by variable-cam resistance training machines match joint torque capability. Eight variable-cam knee extension machines from six different manufacturers were assessed. Resistive torque for a constant weight\\/load was measured at five knee joint angles. Knee extensor muscle torque capabilitythe angletorque relationshipof 10 healthy young men was

Jonathan Folland; Beth Morris

2008-01-01

61

Moderating variables of music training-induced neuroplasticity: a review and discussion.  

PubMed

A large body of literature now exists to substantiate the long-held idea that musicians' brains differ structurally and functionally from non-musicians' brains. These differences include changes in volume, morphology, density, connectivity, and function across many regions of the brain. In addition to the extensive literature that investigates these differences cross-sectionally by comparing musicians and non-musicians, longitudinal studies have demonstrated the causal influence of music training on the brain across the lifespan. However, there is a large degree of inconsistency in the findings, with discordance between studies, laboratories, and techniques. A review of this literature highlights a number of variables that appear to moderate the relationship between music training and brain structure and function. These include age at commencement of training, sex, absolute pitch (AP), type of training, and instrument of training. These moderating variables may account for previously unexplained discrepancies in the existing literature, and we propose that future studies carefully consider research designs and methodologies that control for these variables. PMID:24058353

Merrett, Dawn L; Peretz, Isabelle; Wilson, Sarah J

2013-01-01

62

Training the max-margin sequence model with the relaxed slack variables.  

PubMed

Sequence models are widely used in many applications such as natural language processing, information extraction and optical character recognition, etc. We propose a new approach to train the max-margin based sequence model by relaxing the slack variables in this paper. With the canonical feature mapping definition, the relaxed problem is solved by training a multiclass Support Vector Machine (SVM). Compared with the state-of-the-art solutions for the sequence learning, the new method has the following advantages: firstly, the sequence training problem is transformed into a multiclassification problem, which is more widely studied and already has quite a few off-the-shelf training packages; secondly, this new approach reduces the complexity of training significantly and achieves comparable prediction performance compared with the existing sequence models; thirdly, when the size of training data is limited, by assigning different slack variables to different microlabel pairs, the new method can use the discriminative information more frugally and produces more reliable model; last but not least, by employing kernels in the intermediate multiclass SVM, nonlinear feature space can be easily explored. Experimental results on the task of named entity recognition, information extraction and handwritten letter recognition with the public datasets illustrate the efficiency and effectiveness of our method. PMID:22717449

Niu, Lingfeng; Wu, Jianmin; Shi, Yong

2012-09-01

63

Effect of Training on Physiological and Biochemical Variables of Soccer Players of Different Age Groups  

PubMed Central

Purpose To find out the effect of training on selected physiological and biochemical variables of Indian soccer players of different age groups. Methods A total of 120 soccer players volunteered for the study, were divided (n = 30) into 4 groups: (i) under 16 years (U16), (ii) under 19 years (U19), (iii) under 23 years (U23), (iv) senior (SR). The training sessions were divided into 2 phases (a) Preparatory Phase (PP, 8 weeks) and (b) Competitive Phase (CP, 4 weeks). The training program consisted of aerobic, anaerobic and skill development, and were completed 4 hrs/day; 5 days/week. Selected physiological and biochemical variables were measured at zero level (baseline data, BD) and at the end of PP and CP. Results A significant increase (P < 0.05) in lean body mass (LBM), VO2max, anaerobic power, grip and back strength, urea, uric acid and high density lipoprotein cholesterol (HDL-C); and a significant decrease (P < 0.05) in body fat, hemoglobin (Hb), total cholesterol (TC), triglyceride (TG) and low density lipoprotein cholesterol (LDL-C) were detected in some groups in PP and CP phases of the training when compare to BD. However, no significant change was found in body mass and maximal heart rate of the players after the training program. Conclusion This study would provide useful information for training and selection of soccer players of different age groups. PMID:22375187

Manna, Indranil; Khanna, Gulshan Lal; Chandra Dhara, Prakash

2010-01-01

64

Cryosolenoid valve  

Microsoft Academic Search

An internally piloted shut-off valve is described for use with cryogenic fluids incorporates a short valve housing with normally closed valve closure means incorporated therein and fluid passages with ports for fluid flow therethrough including an elongated extended stem protruding therefrom on top of which a solenoid operator is received in the stem end opening so as to define a

Pauliukonis

1980-01-01

65

Cultural Background Variables in Dance Talent Development: Findings from the UK Centres for Advanced Training  

ERIC Educational Resources Information Center

This study is a qualitative enquiry into cultural background variables--social support, values, race/ethnicity and economic means--in the process of dance talent development. Seven urban dance students in pre-vocational training, aged 15-19, participated in semi-structured interviews. Interviews were inductively analysed using QSR International

Sanchez, Erin N.; Aujla, Imogen J.; Nordin-Bates, Sanna

2013-01-01

66

Heart rate variability reflects training load and psychophysiological status in young elite gymnasts.  

PubMed

In gymnastics, monitoring of the training load and assessment of the psychophysiological status of elite athletes is important for training planning and to avoid overtraining, consequently reducing the risk of injures. The aim of this study was to examine whether heart rate variability (HRV) is a valuable tool to determine training load and psychophysiological status in young elite gymnasts. Six young male elite gymnasts took part in a 10-week observational study. During this period, beat-to-beat heart rate intervals were measured every training day in weeks 1, 3, 5, 7, and 9. Balance, agility, upper limb maximal strength, lower limb explosive, and elastic power were monitored during weeks 2, 4, 6, 8, and 10. Training load of each training session of all 10 weeks was assessed by session rating of perceived exertion (RPE) and psychophysiological status by Foster's index. Morning supine HRV (HF% and LF%/HF%) correlated with the training load of the previous day (r = 0.232, r = -0.279, p < 0.05 ). Morning supine to sitting HRV difference (mean R wave to R wave interval (RR), mean heart rate, HF%, SD1) correlated with session RPE of the previous day (r = -0.320, r = 0.301, p < 0.01; r = 0.265, r = -0.270, p < 0.05) but not with Foster's index. Training day/reference day HRV difference (mean RR, SD1) showed the best correlations with session RPE of the previous day (r = -0.384, r = -0.332, p < 0.01) and Foster's index (r = -0.227, r = -0.260, p < 0.05). In conclusion, HRV, and in particular training day/reference day mean RR difference or SD1 difference, could be useful in monitoring training load and psychophysiological status in young male elite gymnasts. PMID:23364293

Sartor, Francesco; Vailati, Emanuele; Valsecchi, Viola; Vailati, Fulvio; La Torre, Antonio

2013-10-01

67

Fast valve  

DOEpatents

A fast valve is disclosed that can close on the order of 7 milliseconds. It is closed by the force of a compressed air spring with the moving parts of the valve designed to be of very light weight and the valve gate being of wedge shaped with O-ring sealed faces to provide sealing contact without metal to metal contact. The combination of the O-ring seal and an air cushion create a soft final movement of the valve closure to prevent the fast air acting valve from having a harsh closing. 4 figs.

Van Dyke, W.J.

1992-04-07

68

Reliability and variability of day-to-day vault training measures in artistic gymnastics.  

PubMed

Inter-day training reliability and variability in artistic gymnastics vaulting was determined using a customised infra-red timing gate and contact mat timing system. Thirteen Australian high performance gymnasts (eight males and five females) aged 11-23 years were assessed during two consecutive days of normal training. Each gymnast completed a number of vault repetitions per daily session. Inter-day variability of vault run-up velocities (at -18 to -12 m, -12 to -6 m, -6 to -2 m, and -2 to 0 m from the nearest edge of the beat board), and board contact, pre-flight, and table contact times were determined using mixed modelling statistics to account for random (within-subject variability) and fixed effects (gender, number of subjects, number of trials). The difference in the mean (Mdiff) and Cohen's effect sizes for reliability assessment and intra-class correlation coefficients, and the coefficient of variation percentage (CV%) were calculated for variability assessment. Approach velocity (-18 to -2m, CV = 2.4-7.8%) and board contact time (CV = 3.5%) were less variable measures when accounting for day-to-day performance differences, than pre-flight time (CV = 17.7%) and table contact time (CV = 20.5%). While pre-flight and table contact times are relevant training measures, approach velocity and board contact time are more reliable when quantifying vaulting performance. PMID:20806844

Bradshaw, Elizabeth; Hume, Patria; Calton, Mark; Aisbett, Brad

2010-06-01

69

Heart valve surgery  

MedlinePLUS

Valve replacement; Valve repair; Heart valve prosthesis; Mechanical valves, Prosthetic valves ... place. The main types of new valves are: Mechanical -- made of man-made materials, such as metal ( ...

70

Flow metering valve  

DOEpatents

An apparatus for metering fluids at high pressures of about 20,000 to 60,000 psi is disclosed. The apparatus includes first and second plates which are positioned adjacent each other to form a valve chamber. The plates are made of materials which have substantially equal elastic properties. One plate has a planar surface area, and the other a recessed surface area defined by periphery and central lips. When the two plates are positioned in adjacent contacting relationship, a valve chamber is formed between the planar surface area and the recessed surface area. Fluid is introduced into the chamber and exits therefrom when a deformation occurs at positions where they no longer form a valve seat. This permits the metering of fluids at high pressures and at slow variable rates. Fluid then exits from the chamber until an applied external force becomes large enough to bring the valve seats back into contact.

Blaedel, Kenneth L. (Dublin, CA)

1985-01-01

71

Flow metering valve  

DOEpatents

An apparatus for metering fluids at high pressures of about 20,000 to 60,000 psi is disclosed. The apparatus includes first and second plates which are positioned adjacent each other to form a valve chamber. The plates are made of materials which have substantially equal elastic properties. One plate has a planar surface area, and the other a recessed surface area defined by periphery and central lips. When the two plates are positioned in adjacent contacting relationship, a valve chamber is formed between the planar surface area and the recessed surface area. Fluid is introduced into the chamber and exits therefrom when a deformation occurs at positions where they no longer form a valve seat. This permits the metering of fluids at high pressures and at slow variable rates. Fluid then exits from the chamber until an applied external force becomes large enough to bring the valve seats back into contact.

Blaedel, K.L.

1983-11-03

72

Orthostatic influence on heart rate and blood pressure variability in trained persons with tetraplegia  

Microsoft Academic Search

To examine the orthostatic influence on heart rate and blood pressure variability in persons with tetraplegia playing wheelchair\\u000a basketball, ten trained persons with tetraplegia, ten untrained persons with tetraplegia, and ten able-bodied participated\\u000a in this study. Spectrum analysis of the ECG RR interval and blood-pressure on a beat-by-beat basis during head-up tilt 60\\u000a sitting were performed. The ratio of the

Yasuko Otsuka; Norihiro Shima; Toshio Moritani; Kuniharu Okuda; Kyonosuke Yabe

2008-01-01

73

Influence of gender and types of sports training on QT variables in young elite athletes  

Microsoft Academic Search

Influence of gender and sports training on QT variables such as QT interval and dispersion (QT dispersion: QTD) in young elite athletes were evaluated. Subjects included 104 male and 97 female Japanese elite athletes (mean age 21.6 years). Sports included basketball, fencing, gymnastics, judo, swimming, tennis, track and field and volleyball. Age-matched healthy non-athletes (32 men and 20 women) were

Kazuto Omiya; Hiromitsu Sekizuka; Keisuke Kida; Kengo Suzuki; Yoshihiro J. Akashi; Haruo Ohba; Haruki Musha

2012-01-01

74

Increased heart rate variability and executive performance after aerobic training in the elderly  

Microsoft Academic Search

This study examined the effects of two short physical training programs on various parameters of heart rate variability (HRV)\\u000a and on executive performance in older people. Twenty-four sedentary men and women aged 6578years were randomly assigned\\u000a to an aerobic exercise program or a stretching program three times a week for 12weeks. Resting HRV was measured in time and\\u000a frequency domains

Cdric T. Albinet; Geoffroy Boucard; Cdric A. Bouquet; Michel Audiffren

2010-01-01

75

How musical training affects cognitive development: rhythm, reward and other modulating variables  

PubMed Central

Musical training has recently gained additional interest in education as increasing neuroscientific research demonstrates its positive effects on brain development. Neuroimaging revealed plastic changes in the brains of adult musicians but it is still unclear to what extent they are the product of intensive music training rather than of other factors, such as preexisting biological markers of musicality. In this review, we synthesize a large body of studies demonstrating that benefits of musical training extend beyond the skills it directly aims to train and last well into adulthood. For example, children who undergo musical training have better verbal memory, second language pronunciation accuracy, reading ability and executive functions. Learning to play an instrument as a child may even predict academic performance and IQ in young adulthood. The degree of observed structural and functional adaptation in the brain correlates with intensity and duration of practice. Importantly, the effects on cognitive development depend on the timing of musical initiation due to sensitive periods during development, as well as on several other modulating variables. Notably, we point to motivation, reward and social context of musical education, which are important yet neglected factors affecting the long-term benefits of musical training. Further, we introduce the notion of rhythmic entrainment and suggest that it may represent a mechanism supporting learning and development of executive functions. It also hones temporal processing and orienting of attention in time that may underlie enhancements observed in reading and verbal memory. We conclude that musical training uniquely engenders near and far transfer effects, preparing a foundation for a range of skills, and thus fostering cognitive development. PMID:24672420

Miendlarzewska, Ewa A.; Trost, Wiebke J.

2014-01-01

76

How musical training affects cognitive development: rhythm, reward and other modulating variables.  

PubMed

Musical training has recently gained additional interest in education as increasing neuroscientific research demonstrates its positive effects on brain development. Neuroimaging revealed plastic changes in the brains of adult musicians but it is still unclear to what extent they are the product of intensive music training rather than of other factors, such as preexisting biological markers of musicality. In this review, we synthesize a large body of studies demonstrating that benefits of musical training extend beyond the skills it directly aims to train and last well into adulthood. For example, children who undergo musical training have better verbal memory, second language pronunciation accuracy, reading ability and executive functions. Learning to play an instrument as a child may even predict academic performance and IQ in young adulthood. The degree of observed structural and functional adaptation in the brain correlates with intensity and duration of practice. Importantly, the effects on cognitive development depend on the timing of musical initiation due to sensitive periods during development, as well as on several other modulating variables. Notably, we point to motivation, reward and social context of musical education, which are important yet neglected factors affecting the long-term benefits of musical training. Further, we introduce the notion of rhythmic entrainment and suggest that it may represent a mechanism supporting learning and development of executive functions. It also hones temporal processing and orienting of attention in time that may underlie enhancements observed in reading and verbal memory. We conclude that musical training uniquely engenders near and far transfer effects, preparing a foundation for a range of skills, and thus fostering cognitive development. PMID:24672420

Miendlarzewska, Ewa A; Trost, Wiebke J

2013-01-01

77

Valve Disease  

MedlinePLUS

... Heart valves play key roles in this one-way blood flow, opening and closing with each heartbeat. Pressure changes behind and in front of the valves allow them to open their flap-like "doors" (called cusps or leaflets) at just the right time, then close them tightly to prevent a ...

78

Improved Merge Valve  

NASA Technical Reports Server (NTRS)

Circumferential design combines compactness and efficiency. In remotely controlled valve, flow in tributary duct along circumference of primary duct merged with flow in primary duct. Flow in tributary duct regulated by variable throat nuzzle driven by worm gear. Design leak-proof, and most components easily fabricated on lathe.

George-Falvy, Dez

1992-01-01

79

Depressurization valve  

DOEpatents

A depressurization valve for use in relieving completely the pressure in a simplified boiling water reactor is disclosed. The normally closed and sealed valve is provided with a valve body defining a conduit from an outlet of a manifold from the reactor through a valve seat. A closing valve disk is configured for fitting to the valve seat to normally close the valve. The seat below the disk is provided with a radially extending annulus extending a short distance into the aperture defined by the seat. The disk is correspondingly provided with a longitudinally extending annulus that extends downwardly through the aperture defined by the seat towards the high pressure side of the valve body. A ring shaped membrane is endlessly welded to the seat annulus and to the disk annulus. The membrane is conformed over the confronted surface of the seat and disk in a C-sectioned configuration to seal the depressurization valve against the possibility of weeping. The disk is held to the closed position by an elongate stem extending away from the high pressure side of the valve body. The stem has a flange configured integrally to the stem for bias by two springs. The first spring acts from a portion of the housing overlying the disk on the stem flange adjacent the disk. This spring urges the stem and attached disk away from the seat and thus will cause the valve to open at any pressure. A second spring--preferably of the Belleville variety--acts on a latch plate surrounding and freely moving relative to the end of the stem. This second spring overcomes the bias of the first spring and any pressure acting upon the disk. This Belleville spring maintains through its spring force the valve in the closed position. At the same time, the latch plate with its freedom of movement relative to the stem allows the stem to thermally expand during valve temperature excursion. The latch plate in surrounding the stem is limited in its outward movement by a boss attached to the stem at the end of the stem remote from the disk. The latch plate is held normally closed by three radial latches spaced at 120.degree. around the periphery of the plate.

Skoda, George I. (Santa Clara, CA)

1989-01-01

80

Self-regulating valve  

DOEpatents

A variable, self-regulating valve having a hydraulic loss coefficient proportional to a positive exponential power of the flow rate. The device includes two objects in a flow channel and structure which assures that the distance between the two objects is an increasing function of the flow rate. The range of spacing between the objects is such that the hydraulic resistance of the valve is an increasing function of the distance between the two objects so that the desired hydraulic loss coefficient as a function of flow rate is obtained without variation in the flow area.

Humphreys, D.A.

1982-07-20

81

Effect of endurance exercise training on heart rate variability at rest in healthy young and older men  

Microsoft Academic Search

Heart rate variability (HRV) (SD of the RR interval), an index of parasympathetic tone, was measured at rest and during exercise in 13 healthy older men (age 60 to 82 years) and 11 healthy young men (age 24 to 32 years) before and after 6 months of aerobic exercise training. Before exercise training, the older subjects had a 47% lower

Wayne C. Levy; Manuel D. Cerqueira; George D. Harp; Karl-Arne Johannessen; Itamar B. Abrass; Robert S. Schwartz; John R. Stratton

1998-01-01

82

Bicuspid aortic valve  

Microsoft Academic Search

SummaryTwo competitive soccer players aged 23 and 17 years with known bicuspid aortic valve presented for sportsmedical preparticipation\\u000a screening. Both athletes were well trained and had a maximal oxygen uptake of 61 and 60 ml\\/min\\/kg, respectively. Echocardiography\\u000a of the first athlete revealed an eccentric hypertrophy of the left ventricle (enddiastolic diameter 5859 mm, septal and\\u000a posterior myocardial wall thickness 1213

Jrgen Scharhag; T. Meyer; I. Kindermann; G. Schneider; A. Urhausen; W. Kindermann

2006-01-01

83

49 CFR 236.508 - Interference with application of brakes by means of brake valve.  

Code of Federal Regulations, 2010 CFR

...REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Automatic Train Stop, Train Control and Cab Signal Systems Standards...means of brake valve. The automatic train stop, train control, or cab signal...

2010-10-01

84

Yoga as steadiness training: effects on motor variability in young adults.  

PubMed

Exercise training programs can increase strength and improve submaximal force control, but the effects of yoga as an alternative form of steadiness training are not well described. The purpose was to explore the effect of a popular type of yoga (Bikram) on strength, steadiness, and balance. Young adults performed yoga training (n = 10, 29 +/- 6 years, 24 yoga sessions in 8 weeks) or served as controls (n = 11, 26 +/- 7 years). Yoga sessions consisted of 1.5 hours of supervised, standardized postures. Measures before and after training included maximum voluntary contraction (MVC) force of the elbow flexors (EF) and knee extensors (KE), steadiness of isometric EF and KE contractions, steadiness of concentric (CON) and eccentric (ECC) KE contractions, and timed balance. The standard deviation (SD) and coefficient of variation (CV, SD/mean force) of isometric force and the SD of acceleration during CON and ECC contractions were measured. After yoga training, MVC force increased 14% for KE (479 +/- 175 to 544 +/- 187 N, p < 0.05) and was unchanged for the EF muscles (219 +/- 85 to 230 +/- 72 N, p > 0.05). The CV of force was unchanged for EF (1.68 to 1.73%, p > 0.05) but was reduced in the KE muscles similarly for yoga and control groups (2.04 to 1.55%, p < 0.05). The variability of CON and ECC contractions was unchanged. For the yoga group, improvement in KE steadiness was correlated with pretraining steadiness (r = -0.62 to -0.84, p < 0.05); subjects with the greatest KE force fluctuations before training experienced the greatest reductions with training. Percent change in balance time for individual yoga subjects averaged +228% (19.5 +/- 14 to 34.3 +/- 18 seconds, p < 0.05), with no change in controls. For young adults, a short-term yoga program of this type can improve balance substantially, produce modest improvements in leg strength, and improve leg muscle control for less-steady subjects. PMID:18714217

Hart, Cady E F; Tracy, Brian L

2008-09-01

85

Variability of island-induced ocean vortex trains, in the Kuroshio region southeast of Taiwan Island  

NASA Astrophysics Data System (ADS)

This study examines the horizontal scale and spatial characteristics of island-induced ocean vortex trains (IOVTs) in the Kuroshio region southeast of Taiwan Island using European remote sensing satellite ERS-1 SAR imagery. US Aqua satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data are used to analyze the sea surface temperature (SST) features of the study area. Seasonal composites of SST images show that the IOVTs are current-induced vortexes rather than wind-induced ones. Furthermore, using the HYbrid Coordinate Ocean Model/Navy Coupled Ocean Data Assimilation (HYCOM/NCODA) system that generated current and sea surface height anomaly data, the temporal and spatial variability of the Green Island IOVTs is analyzed. The variability of IOVTs within this region shows a distinct seasonality. This seasonal variability of IOVTs is closely associated with the shoreward shift of Kuroshio mainstream driven by the winter northeasterly monsoon. This scenario is verified by vector empirical orthogonal function analysis focused on the weak IOVT period in 2012. In addition to meandering of the Kuroshio, westward-propagating mesoscale eddies and the arrival of typhoons play an important role in modifying the variability of IOVTs at intraseasonal timescale.

Zheng, Zhe-Wen; Zheng, Quanan

2014-06-01

86

Holocene variability of bottom water hydrography on the Kara Sea shelf (Siberia) depicted in multiple single-valve analyses of stable isotopes in ostracods  

Microsoft Academic Search

Ostracods secrete their valve calcite within a few hours or days, therefore, its isotopic composition records ambient environmental conditions of only a short time span. Hydrographic changes between the calcification of individuals lead to a corresponding range (max.min.) in the isotope values when measuring several (?5) single valves from a specific sediment sample. Analyses of living (stained) ostracods from the

Johannes Simstich; Vladimir Stanovoy; Dorothea Bauch; Helmut Erlenkeuser; Robert F. Spielhagen

2004-01-01

87

Analysis of Complex Valve and Feed Systems  

NASA Technical Reports Server (NTRS)

A numerical framework for analysis of complex valve systems supports testing of propulsive systems by simulating key valve and control system components in the test loop. In particular, it is designed to enhance the analysis capability in terms of identifying system transients and quantifying the valve response to these transients. This system has analysis capability for simulating valve motion in complex systems operating in diverse flow regimes ranging from compressible gases to cryogenic liquids. A key feature is the hybrid, unstructured framework with sub-models for grid movement and phase change including cryogenic cavitations. The multi-element unstructured framework offers improved predictions of valve performance characteristics under steady conditions for structurally complex valves such as pressure regulator valve. Unsteady simulations of valve motion using this computational approach have been carried out for various valves in operation at Stennis Space Center such as the split-body valve and the 10-in. (approx.25.4-cm) LOX (liquid oxygen) valve and the 4-in. (approx.10 cm) Y-pattern valve (liquid nitrogen). Such simulations make use of variable grid topologies, thereby permitting solution accuracy and resolving important flow physics in the seat region of the moving valve. An advantage to this software includes possible reduction in testing costs incurred due to disruptions relating to unexpected flow transients or functioning of valve/flow control systems. Prediction of the flow anomalies leading to system vibrations, flow resonance, and valve stall can help in valve scheduling and significantly reduce the need for activation tests. This framework has been evaluated for its ability to predict performance metrics like flow coefficient for cavitating venturis and valve coefficient curves, and could be a valuable tool in predicting and understanding anomalous behavior of system components at rocket propulsion testing and design sites.

Ahuja, Vineet; Hosangadi, Ashvin; Shipman, Jeremy; Cavallo, Peter; Dash, Sanford

2007-01-01

88

Inter-individual variability in adaptation of the leg muscles following a standardised endurance training programme in young women.  

PubMed

There is considerable inter-individual variability in adaptations to endurance training. We hypothesised that those individuals with a low local leg-muscle peak aerobic capacity (VO2peak) relative to their whole-body maximal aerobic capacity (VO2max) would experience greater muscle training adaptations compared to those with a relatively high VO2peak. 53 untrained young women completed one-leg cycling to measure VO2peak and two-leg cycling to measure VO2max. The one-leg VO2peak was expressed as a ratio of the two-leg VO2max (Ratio(1:2)). Magnetic resonance imaging was used to indicate quadriceps muscle volume. Measurements were taken before and after completion of 6 weeks of supervised endurance training. There was large inter-individual variability in the pre-training Ratio(1:2) and large variability in the magnitude of training adaptations. The pre-training Ratio(1:2) was not related to training-induced changes in VO2max (P = 0.441) but was inversely correlated with changes in one-leg VO2peak and muscle volume (P < 0.05). No relationship was found between the training-induced changes in two-leg VO2max and one-leg VO2peak (r = 0.21; P = 0.129). It is concluded that the local leg-muscle aerobic capacity and Ratio(1:2) vary from person to person and this influences the extent of muscle adaptations following standardised endurance training. These results help to explain why muscle adaptations vary between people and suggest that setting the training stimulus at a fixed percentage of VO2max might not be a good way to standardise the training stimulus to the leg muscles of different people. PMID:20369366

McPhee, Jamie S; Williams, Alun G; Degens, Hans; Jones, David A

2010-08-01

89

Design of a gas force simulator for the MIT Electromechanical Valve Drive project  

E-print Network

The MIT electromechanical Valve Drive (EMVD) is a continuously variable valve actuation device for an automotive internal combustion engine. Current experimentation of the EMVD has been limited to intake valve events. When ...

Otten, James S. (James Stewart)

2006-01-01

90

Simulation of a novel electromechanical engine valve drive to quantify performance gains in fuel consumption  

E-print Network

This thesis describes the modeling and simulation of a novel electromechanical valve drive known as the MIT EMV. This valve drive allows an engine to achieve variable valve timing which has been shown to produce improvements ...

Miller, Justin (Justin Lee)

2011-01-01

91

Piezoelectric valve  

DOEpatents

A motorized valve has a housing having an inlet and an outlet to be connected to a pipeline, a saddle connected with the housing, a turn plug having a rod, the turn plug cooperating with the saddle, and a drive for turning the valve body and formed as a piezoelectric drive, the piezoelectric drive including a piezoelectric generator of radially directed standing acoustic waves, which is connected with the housing and is connectable with a pulse current source, and a rotor operatively connected with the piezoelectric generator and kinematically connected with the rod of the turn plug so as to turn the turn plug when the rotor is actuated by the piezoelectric generator.

Petrenko, Serhiy Fedorovich

2013-01-15

92

Orthostatic influence on heart rate and blood pressure variability in trained persons with tetraplegia.  

PubMed

To examine the orthostatic influence on heart rate and blood pressure variability in persons with tetraplegia playing wheelchair basketball, ten trained persons with tetraplegia, ten untrained persons with tetraplegia, and ten able-bodied participated in this study. Spectrum analysis of the ECG R-R interval and blood-pressure on a beat-by-beat basis during head-up tilt 60 degrees sitting were performed. The ratio of the high frequency to total frequency (HF/TF) in the R-R interval decreased from supine (0.5 +/- 0.2) to sitting (0.3 +/- 0.2), and the low frequency (LF) power in systolic blood pressure increased from 4.7 +/- 9.1 to 15.0 +/- 13.1 mmHg(2) only in the untrained persons with tetraplegia (P < 0.01). The decrease in the HF/TF ratio in the untrained persons with tetraplegia indicates attenuated parasympathetic activity to the orthostatic challenge and the similar increase in LF power indicate that parasympathetic activity was reduced and sympathetic activity increased only in these persons. These results suggest that training enhances cardiovascular stability in tetraplegic subjects. PMID:18542988

Otsuka, Yasuko; Shima, Norihiro; Moritani, Toshio; Okuda, Kuniharu; Yabe, Kyonosuke

2008-09-01

93

Design and Experimental Implementation of an Electromagnetic Engine Valve Drive  

E-print Network

In conventional internal combustion engines, engine valve displacements are fixed relative to crankshaft position. If these valves were actuated as a variable function of crankshaft angle, significant improvements in fuel ...

Parlikar, T.A.

94

Plasma valve  

DOEpatents

A plasma valve includes a confinement channel and primary anode and cathode disposed therein. An ignition cathode is disposed adjacent the primary cathode. Power supplies are joined to the cathodes and anode for rapidly igniting and maintaining a plasma in the channel for preventing leakage of atmospheric pressure through the channel.

Hershcovitch, Ady (Mount Sinai, NY); Sharma, Sushil (Hinsdale, IL); Noonan, John (Naperville, IL); Rotela, Elbio (Clarendon Hills, IL); Khounsary, Ali (Hinsdale, IL)

2003-01-01

95

Miniature piezo electric vacuum inlet valve  

DOEpatents

A miniature piezo electric vacuum inlet valve having a fast pulse rate and is battery operated with variable flow capability is disclosed. The low power (<1.6 watts), high pulse rate (<2 milliseconds), variable flow inlet valve is utilized for mass spectroscopic applications or other applications where pulsed or continuous flow conditions are needed. The inlet valve also has a very minimal dead volume of less than 0.01 std/cc. The valve can utilize, for example, a 12 Vdc input/750 Vdc, 3 mA output power supply compared to conventional piezo electric valves which require preloading of the crystal drive mechanism and 120 Vac, thus the valve of the present invention is smaller by a factor of three. 6 figs.

Keville, R.F.; Dietrich, D.D.

1998-03-24

96

Miniature piezo electric vacuum inlet valve  

DOEpatents

A miniature piezo electric vacuum inlet valve having a fast pulse rate and is battery operated with variable flow capability. The low power (<1.6 watts), high pulse rate (<2 milliseconds), variable flow inlet valve is utilized for mass spectroscopic applications or other applications where pulsed or continuous flow conditions are needed. The inlet valve also has a very minimal dead volume of less than 0.01 std/cc. The valve can utilize, for example, a 12 Vdc input/750 Vdc, 3 mA output power supply compared to conventional piezo electric valves which require preloading of the crystal drive mechanism and 120 Vac, thus the valve of the present invention is smaller by a factor of three.

Keville, Robert F. (Valley Springs, CA); Dietrich, Daniel D. (Livermore, CA)

1998-03-24

97

training  

Microsoft Academic Search

This article highlights new nutritional concerns or practices that may influence the adaptation to training. The discussion is based on the assumption that the adaptation to repeated bouts of training occurs during recovery periods and that if one can train harder, the adaptation will be greater. The goal is to maximize with nutrition the recovery\\/adaptation that occurs in all rest

LAWRENCE L. SPRIET; MARTIN J. GIBALA

98

Effects of Exercise Training on Heart Rate Variability in Chagas Heart Disease  

PubMed Central

Background: Heart rate variability (HRV) is a marker of autonomic dysfunction severity. The effects of physical training on HRV indexes in Chagas heart disease (CHD) are not well established. Objective: To evaluate the changes in HRV indexes in response to physical training in CHD. Methods: Patients with CHD and left ventricular (LV) dysfunction, physically inactive, were randomized either to the intervention (IG, N = 18) or control group (CG, N = 19). The IG participated in a 12-week exercise program consisting of 3 sessions/week. Results: Mean age was 49.5 8 years, 59% males, mean LVEF was 36.3 7.8%. Baseline HRV indexes were similar between groups. From baseline to follow-up, total power (TP): 1653 (IQ 625 - 3418) to 2794 (1617 - 4452) ms, p = 0.02) and very low frequency power: 586 (290 - 1565) to 815 (610 - 1425) ms, p = 0.047) increased in the IG, but not in the CG. The delta (post - pre) HRV indexes were similar: SDNN 11.5 30.0 vs. 3.7 25.1 ms. p = 0.10; rMSSD 2 (6 - 17) vs. 1 (21 - 9) ms. p = 0.43; TP 943 (731 - 3130) vs. 1780 (921 - 2743) Hz. p = 0.46; low frequency power (LFP) 1.0 (150 - 197) vs. 60 (111 - 146) Hz. p = 0.85; except for high frequency power, which tended to increase in the IG: 42 (133 - 92) vs. 79 (61 - 328) Hz. p = 0.08). Conclusion: In the studied population, the variation of HRV indexes was similar between the active and inactive groups. Clinical improvement with physical activity seems to be independent from autonomic dysfunction markers in CHD. PMID:25098373

Nascimento, Bruno Ramos; Lima, Marcia Maria Oliveira; Nunes, Maria do Carmo Pereira; de Alencar, Maria Clara Noman; Costa, Henrique Silveira; Pinto Filho, Marcelo Martins; Cota, Vitor Emanuel Serafim; Rocha, Manoel Otavio da Costa; Ribeiro, Antonio Luiz Pinho

2014-01-01

99

Generation of Picosecond Electron-Bunch Trains with Variable Spacing Using a Multi-Pulse Photocathode Laser  

SciTech Connect

We demonstrate the generation of a train of electron bunches with variable spacing at the Argonne Wakefield Accelerator. The photocathode ultraviolet laser pulse consists of a train of four pulses produced via polarization splitting using two alpha-BBO crystals. The photoemitted electron bunches are then manipulated in a horizontally-bending dogleg with variable longitudinal dispersion. A downstream vertically-deflecting cavity is then used to diagnose the temporal profile of the electron beam. The generation of a train composed of four bunches with tunable spacing is demonstrated. Such a train of bunch could have application to, e.g., the resonant excitation of wakefield in dielectric-lined structures. We have presented preliminary measurements on a simple technique to generate a train of electron bunches with variable separation. In the initial experiment appreciable density modulation down to wavelengths of {approx}1.8 mm (corresponding to a temporal separation of {approx}6 ps) were achieved for a total charge of 0.5 nC. Finding ways to reach smaller separations is being explored with the help of numerical simulations and will be presented elsewhere.

Conde, M.; Gai, W.; /Argonne; Jing, C.; /Euclid TechLabs /Argonne; Konecny, R.; Liu, W.; /Argonne; Mihalcea, D.; /Northern Illinois U.; Piot, P.; /Northern Illinois U. /Fermilab; Power, J.G.; /Argonne; Rihaoui, M.; /Northern Illinois U.; Yusof, Z.; /Argonne

2012-07-08

100

Electronic feedback EGR valve  

Microsoft Academic Search

An improved EGR valve controller is described which consists of: (A) body means defining an exhaust gas recirculation passage having an inlet, an outlet and a valve seat disposed in the passage intermediate the inlet and the outlet; (B) a valve member disposed in the EGR passage, the valve member moveable with respect to the valve seat for controlling flow

A. A. Kenny; R. G. Sokalski; L. E. Egle; D. C. Stahly

1986-01-01

101

Artificial Heart Valve Design  

E-print Network

Artificial Heart Valve Design Your Chance to be a Biomedical Engineer #12;Circulatory System Video #12;What is a Heart Valve? · Heart Valve Video #12;#12;What Does a Heart Valve Do? · Maintain the one direction flow of blood through the heart · Heart valves allow blood to flow through in a forward direction

Provancher, William

102

Application of alpha/theta neurofeedback and heart rate variability training to young contemporary dancers: state anxiety and creativity.  

PubMed

As one in a series on the impact of EEG-neurofeedback in the performing arts, we set out to replicate a previous dance study in which alpha/theta (A/T) neurofeedback and heart rate variability (HRV) biofeedback enhanced performance in competitive ballroom dancers compared with controls. First year contemporary dance conservatoire students were randomised to the same two psychophysiological interventions or a choreology instruction comparison group or a no-training control group. While there was demonstrable neurofeedback learning, there was no impact of the three interventions on dance performance as assessed by four experts. However, HRV training reduced anxiety and the reduction correlated with improved technique and artistry in performance; the anxiety scale items focussed on autonomic functions, especially cardiovascular activity. In line with the putative impact of hypnogogic training on creativity A/T training increased cognitive creativity with the test of unusual uses, but not insight problems. Methodological and theoretical implications are considered. PMID:23684733

Gruzelier, J H; Thompson, T; Redding, E; Brandt, R; Steffert, T

2014-07-01

103

Improvement of Circadian Rhythm of Heart Rate Variability by Eurythmy Therapy Training  

PubMed Central

Background. Impairment of circadian rhythm is associated with various clinical problems. It not only has a negative impact on quality of life but can also be associated with a significantly poorer prognosis. Eurythmy therapy (EYT) is an anthroposophic movement therapy aimed at reducing fatigue symptoms and stress levels. Objective. This analysis of healthy subjects was conducted to examine whether the improvement in fatigue symptoms was accompanied by improvements in the circadian rhythm of heart rate variability (HRV). Design. Twenty-three women performed 10 hours of EYT over six weeks. Electrocardiograms (ECGs) were recorded before and after the EYT trial. HRV was quantified by parameters of the frequency and time domains and the nonlinear parameters of symbolic dynamics. Results. The day-night contrast with predominance of vagal activity at night becomes more pronounced after the EYT training, and with decreased Ultralow and very low frequencies, the HRV shows evidence of calmer sleep. During the night, the complexity of the HRV is significantly increased indicated by nonlinear parameters. Conclusion. The analysis of the circadian patterns of cardiophysiological parameters before and after EYT shows significant improvements in HRV in terms of greater day-night contrast caused by an increase of vagal activity and calmer and more complex HRV patterns during sleep. PMID:23533496

Seifert, Georg; Kanitz, Jenny-Lena; Pretzer, Kim; Henze, Gunter; Witt, Katharina; Reulecke, Sina; Voss, Andreas

2013-01-01

104

The effects of concurrent training on performance variables in previously untrained males  

E-print Network

-3 days/week, 20-40 min, 65- 80% HRR), a resistance training (RT, N=13) group performed a resistance training program (2-3 days/week, 3 sets/8 exercises, 6-10 reps, 75-85% 1RM), and a concurrent training (CT, N=16) group performed both the endurance...

Glowacki, Shawn Philip

2005-02-17

105

High speed exhaust gas recirculation valve  

DOEpatents

In order to minimize pollutants such as Nox, internal combustion engines typically include an exhaust gas recirculation (EGR) valve that can be used to redirect a portion of exhaust gases to an intake conduit, such as an intake manifold, so that the redirected exhaust gases will be recycled. It is desirable to have an EGR valve with fast-acting capabilities, and it is also desirable to have the EGR valve take up as little space as possible. An exhaust gas recirculation valve is provided that includes an exhaust passage tube, a valve element pivotally mounted within the exhaust passage tube, a linear actuator; and a gear train. The gear train includes a rack gear operatively connected to the linear actuator, and at least one rotatable gear meshing with the rack gear and operatively connected to the valve element to cause rotation of the valve element upon actuation of the linear actuator. The apparatus provides a highly compact package having a high-speed valve actuation capability.

Fensom, Rod (Peterborough, GB); Kidder, David J. (Peterborough, GB)

2005-01-18

106

Conical Seat Shut-Off Valve  

NASA Technical Reports Server (NTRS)

A moveable valve for controlling flow of a pressurized working fluid was designed. This valve consists of a hollow, moveable floating piston pressed against a stationary solid seat, and can use the working fluid to seal the valve. This open/closed, novel valve is able to use metal-to-metal seats, without requiring seat sliding action; therefore there are no associated damaging effects. During use, existing standard high-pressure ball valve seats tend to become damaged during rotation of the ball. Additionally, forces acting on the ball and stem create large amounts of friction. The combination of these effects can lead to system failure. In an attempt to reduce damaging effects and seat failures, soft seats in the ball valve have been eliminated; however, the sliding action of the ball across the highly loaded seat still tends to scratch the seat, causing failure. Also, in order to operate, ball valves require the use of large actuators. Positioning the metal-to-metal seats requires more loading, which tends to increase the size of the required actuator, and can also lead to other failures in other areas such as the stem and bearing mechanisms, thus increasing cost and maintenance. This novel non-sliding seat surface valve allows metal-to-metal seats without the damaging effects that can lead to failure, and enables large seating forces without damaging the valve. Additionally, this valve design, even when used with large, high-pressure applications, does not require large conventional valve actuators and the valve stem itself is eliminated. Actuation is achieved with the use of a small, simple solenoid valve. This design also eliminates the need for many seals used with existing ball valve and globe valve designs, which commonly cause failure, too. This, coupled with the elimination of the valve stem and conventional valve actuator, improves valve reliability and seat life. Other mechanical liftoff seats have been designed; however, they have only resulted in increased cost, and incurred other reliability issues. With this novel design, the seat is lifted by simply removing the working fluid pressure that presses it against the seat and no external force is required. By eliminating variables associated with existing ball and globe configurations that can have damaging effects upon a valve, this novel design reduces downtime in rocket engine test schedules and maintenance costs.

Farner, Bruce

2013-01-01

107

Heart Valves Explained  

MedlinePLUS

Heart Valves Explained Updated:Jun 23,2014 Learn More About Heart Valves The heart has four chambers. The upper ... Options . Order a brochure of this information here. Heart Valves Are For Life Watch our friendly and ...

108

Fast-Acting Valve  

NASA Technical Reports Server (NTRS)

A fast-acting valve includes an annular valve seat that defines an annular valve orifice between the edges of the annular valve seat, an annular valve plug sized to cover the valve orifice when the valve is closed, and a valve-plug holder for moving the annular valve plug on and off the annular valve seat. The use of an annular orifice reduces the characteristic distance between the edges of the valve seat. Rather than this distance being equal to the diameter of the orifice, as it is for a conventional circular orifice, the characteristic distance equals the distance between the inner and outer radii (for a circular annulus). The reduced characteristic distance greatly reduces the gap required between the annular valve plug and the annular valve seat for the valve to be fully open, thereby greatly reducing the required stroke and corresponding speed and acceleration of the annular valve plug. The use of a valve-plug holder that is under independent control to move the annular valve plug between its open and closed positions is important for achieving controllable fast operation of the valve.

Wojciechowski, Bogdan V. (Inventor); Pegg, Robert J. (Inventor)

2003-01-01

109

Pulmonary valve stenosis  

MedlinePLUS

... valve pulmonary stenosis; Pulmonary stenosis; Stenosis - pulmonary valve; Balloon valvuloplasty - pulmonary ... water pills) Treat abnormal heartbeats and rhythms Percutaneous balloon pulmonary dilation (valvuloplasty) may be performed when no ...

110

Frequency of Ascending Aorta Replacement: A Description of 105 Patients with Bicuspid Aortic Valve Undergoing Aortic Valve Replacement  

Microsoft Academic Search

Background: It has been well documented that patients with a congenital bicuspid aortic valve suffer from earlier valve dysfunction and abnormalities of the ascending aorta, frequently requiring aortic valve replacement and some requiring replacement of the ascending aorta. There have been a few reports with variable data on the frequency of aortic complications, including dilation, aneurysm and dissection, at the

Elizabeth C. Mitchell

2006-01-01

111

Individual training-load and aerobic-fitness variables in premiership soccer players during the precompetitive season.  

PubMed

The aim of this study was to examine the association between individual measures of internal training load (training impulse [TRIMPi]) and aerobic-fitness and performance variables in premiership male soccer players. Eighteen Premiership soccer players (age 28.4 3.2 years, height 182 5.3 cm, body mass 79.9 5.5 kg) performed treadmill tests for VO(2max) and ventilatory threshold (VT) and speed at blood-lactate concentration of 4 mmolL(-1) (S4) on separate days pre and post 8 weeks of training (preseason). The Yo-Yo Intermittent recovery test (Yo-Yo IR1) performance was assessed pre and post preseason training as well. The TRIMPi was calculated using individual lactate and heart-rate profiles and assessed in each training session (n = 900). The results showed that TRIMPi was large to very-large associated with percentage changes in VO(2max) (r = 0.77, p = 0.002), VT (r = 0.78, p = 0.002), S4 (r = 0.64, p = 0.004), and Yo-Yo IR1 performance (r = 0.69, p = 0.009). Regression analyses showed that a weekly TRIMPi >500 AU was necessary to warrant improvements in aerobic fitness and performance in premiership male soccer players during the precompetitive season. It is concluded that TRIMPi is a valid and viable tool to guide training prescription in male premiership soccer players during the preseason. PMID:22648141

Manzi, Vincenzo; Bovenzi, Antonio; Franco Impellizzeri, Maria; Carminati, Ivan; Castagna, Carlo

2013-03-01

112

VO2 Max in Variable Type Exercise Among Well-Trained Upper Body Athletes.  

ERIC Educational Resources Information Center

The maximal oxygen consumption (VO2 max) of well-trained upper body athletes was compared to that of untrained individuals in four types of exercise: arm cranking, legs only cycling, graded treadmill running, and combined arm cranking and leg cycling. Results of the study showed that well-trained upper body athletes attained a significantly higher

Seals, Douglas R.; Mullin, John P.

1982-01-01

113

Liquid rocket valve components  

NASA Technical Reports Server (NTRS)

A monograph on valves for use with liquid rocket propellant engines is presented. The configurations of the various types of valves are described and illustrated. Design criteria and recommended practices for the various valves are explained. Tables of data are included to show the chief features of valve components in use on operational vehicles.

1973-01-01

114

Rotary pneumatic valve  

DOEpatents

A rotary pneumatic valve which is thrust balanced and the pneumatic pressure developed produces only radial loads on the valve cylinder producing negligible resistance and thus minimal torque on the bearings of the valve. The valve is multiplexed such that at least two complete switching cycles occur for each revolution of the cylinder spindle.

Hardee, Harry C. (Albuquerque, NM)

1991-01-01

115

Correlation of heart rate variability with cardiac functional and metabolic variables in cyclists with training induced left ventricular hypertrophy  

Microsoft Academic Search

OBJECTIVETo examine the correlation between heart rate variability and left ventricular mass in cyclists with an athletes heart.METHODSLeft ventricular mass and diastolic function were determined at rest and myocardial high energy phosphates were quantified at rest and during atropinedobutamine stress in 12 male cyclists and 10 control subjects, using magnetic resonance techniques. Ambulatory 24 hour ECG recordings were obtained, and

B M Pluim; C A Swenne; A H Zwinderman; A C Maan; A van der Laarse; J Doornbos; E E Van der Wall

1999-01-01

116

Valve for fluid control  

DOEpatents

A valve for controlling fluid flows. This valve, which includes both an actuation device and a valve body provides: the ability to incorporate both the actuation device and valve into a unitary structure that can be placed onto a microchip, the ability to generate higher actuation pressures and thus control higher fluid pressures than conventional microvalves, and a device that draws only microwatts of power. An electrokinetic pump that converts electric potential to hydraulic force is used to operate, or actuate, the valve.

Oborny, Michael C. (Albuquerque, NM); Paul, Phillip H. (Livermore, CA); Hencken, Kenneth R. (Pleasanton, CA); Frye-Mason, Gregory C. (Cedar Crest, NM); Manginell, Ronald P. (Albuquerque, NM)

2001-01-01

117

Magnetically operated check valve  

NASA Astrophysics Data System (ADS)

A magnetically operated check valve is disclosed having, in one aspect, a valve body and a movable poppet disposed therein. A magnet attracts the poppet to hold the valve shut until the force of fluid flow through the valve overcomes the magnetic attraction and moves the poppet to an unseated, open position. The poppet and magnet are configured and disposed to trap a magnetically attracted particulate and prevent it from flowing to a valve seating region.

Morris, Brian G.; Bozeman, Richard J., Jr.

1993-03-01

118

[The state of central hemodynamics and variability of hearty rate in sportsmen with various direction of training process].  

PubMed

The state of the central hemodynamic and variability of heart rate (VHR) in high quality sportsmen with various direction of training processes in conditions of relative tranquility was investigated. Was discovered that in sportsmen during the endurance training (group "Endurance", n = 27) and in strength training (group "Strength", n = 17) was noted the decrease in total peripheral blood resistance (TPBR: -15%, p = 0.003 and -16%, p = 0.011 for groups "Endurance" and "Strength" accordingly). However, in group "Strength" the minute blood volume (MBV) was increased (p = 0.012), and temporal and spectral data ofVHR (RMSSD, PNN50, HF)--decreased (p < 0.05) in comparison with control group (n = 56). Part of this differences had to do with increase body mass index (p = 0.005) in the group "Strength". In "Endurance" group the VHR were increased (RMSSD, pNN50, HF, VLF, TP all p < 0.02), the mean arterial pressure was decreased (p < 0.003) without considerable differences in MVB in comparison with the control group. The received data allows to conclude, that in the state of tranquility, the hemodynamic maintenance of the organism of the sportsmen of the "Strength" group takes place on a higher level of MBV and the mechanisms of heart regulation tension. On the other hand, in sportsmen training in endurance, the low level of MBV is taken care of by less tension of the regulation mechanisms of the heart action (higher tonus of vagus). PMID:20196455

Mal'tsev, A Iu; Mel'nikov, A A; Vikulov, A D; Gromova, K S

2010-01-01

119

Muscle Strength and Damage Following Two Modes of Variable Resistance Training  

PubMed Central

Nautilus Machine (NM) and Elastic Resistance (ER) have gained considerable popularity among athletes and recreational lifters seeking to increase muscle strength. However, there is controversy concerning the use of ER for increasing muscle hypertrophy and strength among healthy-trained individuals. The aim of the study was to compare the effect of repeated near maximal contractions by ER/NM on indicators of muscle damage including: maximal strength decrement (MVIC), rate of muscle soreness (DOMS), concentration of plasma creatine kinase (CK) and increased high muscle signal on T2 weighted images using magnetic resonance imaging (MRI). Nine healthy male subjects completed two modalities of exercise (5 sets 10RM ER/NM) in a counterbalance cross-over study design with three weeks wash-out period between experiments. The MVIC was measured and DOMS rated and recorded for 4 consecutive days while blood samples were collected on day 1, 3, 5 and 7. Prior to and forty eight hours after completion of each mode of exercise, subjects underwent MRI scanning. The average of applied forces demonstrated significantly higher value for NM compared with ER (362 34.2 N vs 266.73 44.6 N respectively) throughout the 5 sets of dynamic exercise (all p < 0.05). However, the indicators of muscle damage (T2 relaxation time, DOMS, MVIC and serum CK) exhibited a very similar response across both modes of training. Plasma CK increased significantly following both modes of training with the peak value on Day 3 (p < 0.05). The time course of muscle soreness reached a significant level after both modes of exercise and showed a peak value on the 2nd day (p < 0.05). The T2 relaxation time demonstrated a statistically significant increase following ER and NM compared with the pre-test value (p < 0.05). The similarity of these responses following both the ER and NM exercise training session suggests that both modes of training provide a similar training stress; despite a considerably lower external force generation during ER. The importance of these findings is underlined by the fact that exercise-induced muscle damage has been shown to be the underlying mechanism of further muscle hypertrophy. Key points Exercise induced muscle soreness increased levels of plasma CK, increased MRI T2 signal and prolonged strength loss indicate the moderate to intense nature of the training protocol. The similarity of these responses following both the Elastic Resistance and Nautilus Machine exercise training session suggests that both modes of training provide a similar training stress; despite a considerably lower external force generation during ER. The data in the present study suggest elastic training is a viable mode of resistance exercise that can provide a training stimulus greater than that employed in rehabilitation settings. PMID:24149552

Aboodarda, Saied Jalal; George, John; Mokhtar, Abdul Halim; Thompson, Martin

2011-01-01

120

Quickly Removable Valve  

NASA Technical Reports Server (NTRS)

Unit removed with minimal disturbance. Valve inlet and outlet ports adjacent to each other on same side of valve body. Ports inserted into special manifold on fluid line. Valve body attached to manifold by four bolts or, alternatively, by toggle clamps. Electromechanical actuator moves in direction parallel to fluid line to open and close valve. When necessary to clean valve, removed simply by opening bolts or toggle clamps. No need to move or separate ports of fluid line. Valve useful where disturbance of fluid line detrimental or where fast maintenance essential - in oil and chemical industries, automotive vehicles, aircraft, and powerplants.

Robbins, John S.

1988-01-01

121

Transcatheter aortic valve implantation  

PubMed Central

Transcatheter aortic valve implantation was developed to offer a therapeutic solution to patients with severe symptomatic aortic stenosis who are not candidates for conventional aortic valve replacement. The improvement in transcatheter aortic valve implantation outcomes is still of concern in the areas of stroke, vascular injury, heart block, paravalvular regurgitation and valve durability. Concomitantly, the progress, both technical and in terms of material advances of transcatheter valve systems, as well as in patient selection, renders transcatheter aortic valve implantation an increasingly viable treatment for more and more patients with structural heart disease. PMID:25374670

Oliemy, Ahmed

2014-01-01

122

A novel optimization procedure for training of fuzzy inference systems by combining variable structure systems technique and Levenberg-Marquardt algorithm  

Microsoft Academic Search

This paper presents a novel training algorithm for fuzzy inference systems. The algorithm combines the Levenberg-Marquardt algorithm with variable structure systems approach. The combination is performed by expressing the parameter update rule in continuous time and application of sliding mode control method to the gradient based training procedure. The proposed combination therefore exhibits a degree of robustness to the unmodeled

Mehmet nder Efe; Okyay Kaynak

2001-01-01

123

Pulse Train Generator for Producing Odd or Even Number of Pulses with Variable Pulse Spacing.  

National Technical Information Service (NTIS)

The pulse train generator is for use in computer circuitry. In the basic embodiment there is a plurality of monostable multivibrators and an odd number of pulses are generated for each trigger signal. The structure in a second embodiment is the same in th...

M. F. Williams, A. F. Thornhill

1965-01-01

124

Heart valve surgery - series (image)  

MedlinePLUS

... heart valves are either natural (biologic) or artificial (mechanical). Natural valves are from human donors (cadavers), modified ... artificial valves will require anticoagulation. The advantage of mechanical valves is that they last longer-thus, the ...

125

What Is Heart Valve Surgery?  

MedlinePLUS

... Ask your doctor about the different kinds used. Heart valve surgery is done to replace or repair heart valves ... left atrium from the left ventricle. What Is Heart Valve Surgery? ANSWERS by heart Treatments + Tests If a valve ...

126

Options for Heart Valve Replacement  

MedlinePLUS

... position of the damaged valve aortic valve TAVI/TAVR procedure Transcatheter aortic valve replacement Newer surgery options ... Replacement - Ross Procedure - Newer Surgery Options - What is TAVR? - Types of Replacement Valves Healthy Living Goals Personal ...

127

Exercise performance and cardiovascular health variables in 70-year-old male soccer players compared to endurance-trained, strength-trained and untrained age-matched men.  

PubMed

The aim was to investigate performance variables and indicators of cardiovascular health profile in elderly soccer players (SP, n = 11) compared to endurance-trained (ET, n = 8), strength-trained (ST, n = 7) and untrained (UT, n = 7) age-matched men. The 33 men aged 65-85 years underwent a testing protocol including measurements of cycle performance, maximal oxygen uptake (VO2max) and body composition, and muscle fibre types and capillarisation were determined from m. vastus lateralis biopsy. In SP, time to exhaustion was longer (16.3 2.0 min; P < 0.01) than in UT (+48%) and ST (+41%), but similar to ET (+1%). Fat percentage was lower (P < 0.05) in SP (-6.5% points) than UT but not ET and ST. Heart rate reserve was higher (P < 0.05) in SP (104 16 bpm) than UT (+21 bpm) and ST (+24 bpm), but similar to ET (+2 bpm), whereas VO2max was not significantly different in SP (30.2 4.9 ml O2 min(-1) kg(-1)) compared to UT (+14%) and ST (+9%), but lower (P < 0.05) than ET (-22%). The number of capillaries per fibre was higher (P < 0.05) in SP than UT (53%) and ST (42%) but similar to ET. SP had less type IIx fibres than UT (-12% points). In conclusion, the exercise performance and cardiovascular health profile are markedly better for lifelong trained SP than for age-matched UT controls. Incremental exercise capacity and muscle aerobic capacity of SP are also superior to lifelong ST athletes and comparable to endurance athletes. PMID:24787613

Randers, Morten Bredsgaard; Andersen, Jesper L; Petersen, Jesper; Sundstrup, Emil; Jakobsen, Markus D; Bangsbo, Jens; Saltin, Bengt; Krustrup, Peter

2014-01-01

128

Control of Charge Dilution in Turbocharged Diesel Engines via Exhaust Valve Timing  

E-print Network

to intake manifold. The flow of eEGR is typically regulated by the EGR valve. Well-tuned and highly, such as a venturi system, intake EGR throttle, Variable Geometry Turbocharger (VGT), or exhaust back-pressure valve, Variable Geometry Turbocharger, Exhaust Back-Pressure Valve Internal Exhaust Gas Recirculation (iEGR

Stefanopoulou, Anna

129

Interindividual variability of electromyographic patterns and pedal force profiles in trained cyclists  

Microsoft Academic Search

The aim of this study was to determine whether high inter-individual variability of the electromyographic (EMG) patterns during\\u000a pedaling is accompanied by variability in the pedal force application patterns. Eleven male experienced cyclists were tested\\u000a at two submaximal power outputs (150 and 250W). Pedal force components (effective and total forces) and index of mechanical\\u000a effectiveness were measured continuously using instrumented

Franois Hug; Jean Marc Drouet; Yvan Champoux; Antoine Couturier; Sylvain Dorel

2008-01-01

130

Absent pulmonary valve  

MedlinePLUS

... that bring air to the lungs (bronchi) and cause breathing problems. Other heart defects that can occur with absent pulmonary valve include: Abnormal tricuspid valve Atrial septal defect Double ...

131

Aortic valve surgery - open  

MedlinePLUS

... There are two main types of new valves: Mechanical -- made of man-made materials, such as titanium ... Mechanical heart valves do not fail often. However, blood clots can develop on them. If a blood ...

132

Mitral valve surgery - open  

MedlinePLUS

... place. There are two types of mitral valves: Mechanical -- made of man-made (synthetic) materials, such as ... Mechanical heart valves do not fail often. They last from 12-20 years. However, blood clots develop ...

133

Solenoid valve maintenance and application guide  

SciTech Connect

Solenoid operated valves (SOV) are used widely in the nuclear power industry, both in safety related and balance of plant systems. Due to a number of reported failures and malfunctions, solenoid valves have recently drawn wide attention from regulatory agencies and plant maintenance personnel. This NMAC document is designed to help power plant personnel understand, evaluate, and resolve any potential maintenance problem related to the operation of solenoid valves. It can also be used for training of maintenance personnel and system engineers. The guide provides detailed information about SOV operation, as well as the limitations and design characteristics which should be considered when selecting a valve for application. It also describes various modes of failure and evaluates industry wide failure data. In addition, descriptions of various troubleshooting, maintenance, and repair methods are included.

Holzman, P. (Strategic Technology and Resources, Winchester, MA (United States))

1992-04-01

134

Ball valves solve turbine drain valve problem  

SciTech Connect

Alabama Power's E.C. Gaston generating plant, a 1904-MW facility located 40 miles south of Birmingham, consists of four 250-MW units, one 884-MW unit, and a 20-MW combustion turbine. Over the years the utility has experienced recurring failure of turbine drain valves on Gaston Unit 5. Unit 5 uses a Combustion Engineering supercritical steam generator rated at 6,351,470 lb/hr main steam flow to deliver steam to a General Electric tandem-compound reheat turbine with a rated capacity of 884 MW at 3500 psig and 1000 F. Main steam enters the turbine through four combined stop and control valves mounted independent of the turbine shell. This paper reports that each stop and control valve is equipped with two before-seat drain valves. One of the drain valves is motor-operated to facilitate remote operation: the other is a manual valve. In an effort to improve drain systems and reduce costs, alternatives to the problem-ridden Y-pattern glove valves were investigated. One such alternative was the Mogas severe-service metal-seated ball valve.

McDaniel, P. (Alabama Power Co., Birmingham, AL (United States))

1992-01-01

135

Valve technology: A compilation  

NASA Technical Reports Server (NTRS)

A technical compilation on the types, applications and modifications to certain valves is presented. Data cover the following: (1) valves that feature automatic response to stimuli (thermal, electrical, fluid pressure, etc.), (2) modified valves changed by redesign of components to increase initial design effectiveness or give the item versatility beyond its basic design capability, and (3) special purpose valves with limited application as presented, but lending themselves to other uses with minor changes.

1971-01-01

136

Stemless Ball Valve  

NASA Technical Reports Server (NTRS)

This invention utilizes a new method of opening and closing a ball valve. Instead of rotating the ball with a perpendicular stem (as is the case with standard ball valves), the ball is rotated around a fixed axis by two guide pins. This innovation eliminates the leak point that is present in all standard ball valves due to the penetration of an actuation stem through the valve body. The VOST (Venturi Off-Set-Technology) valve has been developed for commercial applications. The standard version of the valve consists of an off-set venturi flow path through the valve. This path is split at the narrowest portion of the venturi, allowing the section upstream from the venturi to be rotated. As this rotation takes place, the venturi becomes restricted as one face rotates with respect to the other, eventually closing off the flow path. A spring-loaded seal made of resilient material is embedded in the upstream face of the valve, making a leak-proof seal between the faces; thus a valve is formed. The spring-loaded lip seal is the only seal that can provide a class six, or bubble-tight, seal against the opposite face of the valve. Tearing action of the seal by high-velocity gas on this early design required relocation of the seal to the downstream face of the valve. In the stemless embodiment of this valve, inner and outer magnetic cartridges are employed to transfer mechanical torque from the outside of the valve to the inside without the use of a stem. This eliminates the leak path caused by the valve stems in standard valves because the stems penetrate through the bodies of these valves.

Burgess, Robert K.; Yakos, David; Walthall, Bryan

2012-01-01

137

Heart Valve Diseases  

MedlinePLUS

Your heart has four valves. Normally, these valves open to let blood flow through or out of your heart, and then shut to keep it from flowing ... close tightly. It's one of the most common heart valve conditions. Sometimes it causes regurgitation. Stenosis - when ...

138

Pressure regulating valve controller  

Microsoft Academic Search

In an aircraft cabin air conditioning system comprising a pair of air cycle refrigeration systems which provide chilled air to the cabin, airflow through the air cycle refrigeration systems being controllable by a pair of pressure regulating valves, each of the pressure regulating valves being disposed in a corresponding main airflow conduit and operated by a corresponding pneumatic valve actuator,

1988-01-01

139

Lock For Valve Stem  

NASA Technical Reports Server (NTRS)

Simple, cheap device locks valve stem so its setting cannot be changed by unauthorized people. Device covers valve stem; cover locked in place with standard padlock. Valve lock made of PVC pipe and packing band. Shears, drill or punch, and forming rod only tools needed.

Burley, Richard K.; Guirguis, Kamal S.

1991-01-01

140

Dual flapper valve assembly  

SciTech Connect

This patent describes a dual flapper valve assembly for limiting the loss of completion fluid in connection with a well service operation. The valve assembly consists of: tubular support means defining a flow passage; a first flapper valve assembly connected in series flow relation with the support means, the first flapper valve assembly having a valve closure member movable between first and second positions for closing and opening the flow passage; a second flapper valve assembly connected in series flow relation in the support means, the second flapper valve assembly having a valve closure member movable between open and closed passage positions for closing and opening the flow passage; a prop sleeve mounted within the support means, the prop sleeve being movable from an extended position in which it props the closure member of one flapper valve in the open passage position to a retracted position in which the closure member is disengaged and released for movement to the closed passage position, the valve closure member of one of the flapper valve assemblies being engageable by a wash pipe extending through the flow passage to prop the valve closure member in the open passage position, and being movable to the closed passage position upon retraction of the wash pipe out of the flow passage.

Clary, S.R.; Giusti, F. Jr.; Sproul, R.M.

1989-07-11

141

Transcatheter valve-in-valve aortic valve implantation: 16-month follow-up.  

PubMed

Off-pump transcatheter, transapical valve-in-valve aortic valve implantation into a failed surgically implanted aortic valve was successfully performed in an 85-year-old man. He was discharged on postoperative day 5, and remained well at his 16-month follow-up. Echocardiography at 12 months showed normal prosthetic valve function without displacement, recoil, or regurgitation. Transcatheter transapical valve-in-valve aortic valve implantation is feasible and could be a viable approach for selected patients. PMID:19766829

Ye, Jian; Webb, John G; Cheung, Anson; Masson, Jean-Bernard; Carere, Ronald G; Thompson, Christopher R; Munt, Brad; Moss, Robert; Lichtenstein, Samuel V

2009-10-01

142

Nonlinear System Modeling, Optimal Cam Design, and Advanced System Control for an Electromechanical Engine Valve Drive  

E-print Network

A cam-based shear force-actuated electromechanical valve drive system offering variable valve timing in internal combustion engines was previously proposed and demonstrated. To transform this concept into a competitive ...

Qiu, Yihui

143

The Role of Aerobic and Anaerobic Training Programs on CD(34+) Stem Cells and Chosen Physiological Variables.  

PubMed

Exercise is one of the most powerful non-pharmacological strategies, which can affect nearly all cells and organs in the body. Changes in the behavior of adult stem cells have been shown to occur in response to exercise. Exercise may act on regenerative potential of tissues by altering the ability to generate new stem cells and differentiated cells that are able to carry out tissue specific functions. The purpose of this study was to reveal the role of aerobic and anaerobic training programs on CD34+ Stem Cells and chosen physiological variables. Twenty healthy male athletes aged 18-24 years were recruited for this study. Healthy low active males and BMI matched participants (n=10) aged 20-22 years were recruited as controls. Aerobic and anaerobic training programs for 12 weeks were conducted. VO2max pulse observation was carried out using the Astrand Rhyming protocol. RBCs, WBCs, HB and hematocrit were estimated using a coulter counter, lactate by the Accusport apparatus, CD34+ stem cells by flow cytometry. VO2max was increased significantly in case of the aerobic training program compared to anaerobic one (622.2 ml/kg/min vs. 542.1 ml/kg/min). Haemotological values increased significantly in the anaerobic program when compared to the aerobic one, RBCs (5.30.3 and 4.90.2 mln/ul), WBCs (6.60.5 and 6.10.4 thous/ul), HB (15.40.4 and 14.20.5 g/de), Hematocrit (4.61.2 and 4.41.1 %), CD34+ stem cells count increased significantly in case of the anaerobic program compared to the aerobic (251.621.64 and 13014.61) and sedentary one (17224.10). These findings suggest that anaerobic training programs provoke better adaptation to exercise and stem cell counts may differ between trained and sedentary subjects. Circulating immature cells are likely to be involved in angiogenesis and repair process, both mechanisms being associated with strenuous exercise. Knowledge of the physiological effects of training on stem cells might be of potential clinical use. PMID:23486555

Shalaby, Mohammed Nader; Saad, Mohammed; Akar, Samy; Reda, Mubarak Abdelreda Ali; Shalgham, Ahmed

2012-12-01

144

Compact valve actuation mechanism  

NASA Technical Reports Server (NTRS)

A valve actuation device. The device may include a free floating valve bridge movably supported within a cavity in the engine housing. The bridge may be provided with a cavity and an orifice arrangement for pumping gases entrained with lubricating fluid toward the piston stems as the bridge reciprocates back and forth. The device may also include a rocker arm that has a U-shaped cross-sectional shape for receiving at least a portion of the valve bridge, valve stem valve spring and spring retainer therein. The rocker arm may be provided with lubrication passages for directing lubrication to the point wherein it is pivotally affixed to the engine housing.

Brogdon, James William (Inventor); Gill, David Keith (Inventor)

2000-01-01

145

Multiobjective analysis for the design and control of an electromagnetic valve actuator  

Microsoft Academic Search

The electromagnetic valve actuator can deliver much improved fuel efficiency and reduced emissions in spark ignition (SI) engines owing to the potential for variable valve timing when compared with cam-operated, or conventional, variable valve strategies. The possibility exists to reduce pumping losses by throttle-free operation, along with closed-valve engine braking. However, further development is required to make the technology suitable

P Stewart; D Gladwin; P J Fleming

2007-01-01

146

Rotary-To-Axial Motion Converter For Valve  

NASA Technical Reports Server (NTRS)

Nearly frictionless mechanism converts rotary motion into axial motion. Designed for use in electronically variable pressure-regulator valve. Changes rotary motion imparted by motor into translation that opens and closes valve poppet. Cables spaced equidistantly around edge of fixed disk support movable disk. As movable disk rotated, cables twist, lifting it. When rotated in opposite direction, cables untwist, lowering it. Spider disk helps to prevent cables from tangling. Requires no lubrication and insensitive to contamination in fluid flowing through valve.

Reinicke, Robert H.; Mohtar, Rafic

1991-01-01

147

Simulation of a Hydraulic Pump Control Valve  

NASA Technical Reports Server (NTRS)

This paper describes the mode of operation of a control valve assembly that is used with a hydraulic pump. The operating system of the valve is modelled in a simplified form, and an analogy for hydraulic resonance of the pressure sensing system is presented. For the control valve investigated, air entrainment, length and diameter of the resonator neck, and valve mass produced the greatest shift in resonant frequency. Experimental work was conducted on the hydraulic system so that the resonance levels and frequencies could be measured and the accuracy of the theory verified. The results obtained make it possible to evaluate what changes to any of the variables considered would be most effective in driving the second harmonic frequency above the operating range.

Molen, G. Vander; Akers, A.

1987-01-01

148

Bicuspid aortic valve endocarditis complicated by mitral valve aneurysm.  

PubMed

We describe a case of mitral valve aneurysm associated with concomitant aortic valve endocarditis. Aneurysms appear as a localized saccular bulge of the anterior leaflet into the left atrium and thus are often misdiagnosed as mitral valve prolapse, myxomatous mitral valve, or atrial myxoma. The presentation and management of mitral valve aneurysms are the subject of this case report.? PMID:21447085

Ruparelia, Neil; Lawrence, David; Elkington, Andrew

2011-05-01

149

Interval training in elderly men increases both heart rate variability and baroreflex activity  

Microsoft Academic Search

\\u000a Abstract\\u000a \\u000a Aims\\u000a Autonomic nervous system activity decreases continuously with age and appears to be a powerful predictor of disease and death. Attempts are thus made to reactivate autonomic drive with the intent of improving health.\\u000a Methods\\u000a We assessed maximal oxygen consumption (VO2max), auto- nomic nervous system activity by heart rate variability (HRV) analysis and spontaneous cardiac baroreflex activity (SBR) in

Vincent Pichot; Frdric Roche; Christian Denis; Martin Garet; David Duverney; Frdric Costes; Jean-Claude Barthlmy

2005-01-01

150

Respiratory compensation and blood pH regulation during variable intensity exercise in trained versus untrained subjects.  

PubMed

To determine whether endurance-trained cyclists (T; n = 10) have a superior blood-respiratory buffering for metabolic acidosis relative to untrained subjects (UT; n = 10) during variable intensity exercise (VAR). On three occasions, T and UT pedaled for 24 min alternating high- and low-intensities as percentage of their second ventilatory threshold (VT2): VAR(LOW) 87.5-37.5% VT2, VAR(MODERATE) 125-25% VT2, and VAR(HIGH) 162.5-12.5% VT2 to complete the same amount of work. Before and just after each VAR trial, maximal cycling power (P(MAX)) was assessed. For each trial, the respiratory compensation for exercise acidosis (ventilatory equivalent for CO2) and the final blood pH, lactate and bicarbonate concentrations were similar for T and UT subjects. However, after VAR(HIGH), UT reduced P(MAX) (-14 +/- 1%; P < 0.05) while T did not. Our data suggest that endurance training confers adaptations to withstand the low pH provoked by VAR without losing cycling power, although this response is not due to differences in blood-respiratory buffering. PMID:19513741

Del Coso, Juan; Hamouti, Nassim; Aguado-Jimenez, Roberto; Mora-Rodriguez, Ricardo

2009-09-01

151

Variability and information content in auditory cortex spike trains during an interval-discrimination task.  

PubMed

Processing of temporal information is key in auditory processing. In this study, we recorded single-unit activity from rat auditory cortex while they performed an interval-discrimination task. The animals had to decide whether two auditory stimuli were separated by either 150 or 300 ms and nose-poke to the left or to the right accordingly. The spike firing of single neurons in the auditory cortex was then compared in engaged vs. idle brain states. We found that spike firing variability measured with the Fano factor was markedly reduced, not only during stimulation, but also in between stimuli in engaged trials. We next explored if this decrease in variability was associated with an increased information encoding. Our information theory analysis revealed increased information content in auditory responses during engagement compared with idle states, in particular in the responses to task-relevant stimuli. Altogether, we demonstrate that task-engagement significantly modulates coding properties of auditory cortical neurons during an interval-discrimination task. PMID:23945780

Abolafia, Juan M; Martinez-Garcia, M; Deco, G; Sanchez-Vives, M V

2013-11-01

152

Pneumatic Directional Control Valves  

NSDL National Science Digital Library

This learning object examines pneumatic directional control valves in two-way, three-way, and four-way valves. The presentation is interactive, as it allows the user to focus of certain valve types and cater their learning towards those. The site employs flash based animations, and also many other diagrams to address certain points. Overall, this site has nice presentation and allows presents a great deal of information.

Bartelt, Terry L.; Tomlin, Bonnie

2008-11-24

153

Bicuspid aortic valve  

Microsoft Academic Search

Key Words Disease Name Definition\\/diagnostic criteria Etiology Clinical description Diagnostic Methods Epidemiology Genetic Councelling Management References Abstract The usual arrangement of the aortic valve is for it to have three leaflets; these are termed the right and left coronary leaflets and the non-coronary leaflet. Bicuspid aortic valve (BAV) describes a valve with two leaflets. It can be detected using cross-sectional

Chris Bennett; Jonathan Parsons

2005-01-01

154

Pneumatic flow control valve using particle excitation by PZT transducer  

Microsoft Academic Search

This paper reports a flow control valve for pneumatic actuators. This flow control valve has a lightweight and simple structure using particle excitation by PZT transducer, which is driven at resonance mode and it can be used as a variable speed controller for pneumatic actuators. A PZT transducer has been used for controlling flow rate in this study. The flow

Daisuke Hirooka; Koichi Suzumori; Takefumi Kanda

2009-01-01

155

Prosthetic heart valves.  

PubMed

Heart valve replacements improve symptoms and life expectancy but may have potential problems. Biological replacements have limited durability but do not require anticoagulation and are usually used for the relatively elderly. Mechanical valves have a virtually zero primary failure rate but require anticoagulation and are usually used for the relatively younger patient. Transcatheter valves are used for patients in whom conventional surgery is not technically feasible or who have significant comorbidities. This article discusses the management of patients after valve replacement and discusses future developments. PMID:24423099

Chambers, J

2014-10-01

156

Tubing drain valve  

SciTech Connect

A method is described for operating a valve means. The valve means comprises a tubular piston movable within a tubular member suitable for use in a borehole pipe string to open and close a port through the wall of the tubular member. The method comprises: biassing the valve means in its closed position; pressurizing the interior of the piston to a predetermined pressure to overcome the biassing closed force and to actuate the valve means to its open position; biassing the valve means to its open position; and actuating the valve means to its closed position by engaging a first arm of a dog pivotally mounted on the piston with an engaging means insertable through the interior of the tubular piston; moving the piston relative to the tubular member; rotating the dog about its pivot to bring a second arm of the dog into contact with a detent in the tubular member; and applying sufficient force to the first arm to continue rotating the dog about the pivot, while engaging the detent with the second arm of the dog, in order to overcome the biassing open force to actuate the valve means to its closed position. A tubing drain valve suitable for use in a borehole pipe string, comprising: a sub suitable for incorporating within a borehole pipe string; and a port between the interior and the exterior of the sub; and valve means for opening and closing the port.

Soderberg, P.B.

1987-02-24

157

A low power, on demand electrothermal valve for wireless drug delivery applications  

PubMed Central

We present a low power, on demand Parylene MEMS electrothermal valve. A novel ?-shaped thermal resistive element requires low power (~mW) and enables rapid valve opening (~ms). Using both finite element analysis and valve opening experiments, a robust resistive element design for improved valve opening performance in water was obtained. In addition, a thermistor, as an inrush current limiter, was added into the valve circuit to provide variable current ramping. Wireless activation of the valve using RF inductive power transfer was demonstrated. PMID:20024057

Li, Po-Ying; Givrad, Tina K.; Sheybani, Roya; Holschneider, Daniel P.; Maarek, Jean-Michel I.

2014-01-01

158

Use of a Melody Pulmonary Valve in Transcatheter Valve-in-Valve Replacement for Tricuspid Valve Bioprosthesis Degeneration  

PubMed Central

Bioprosthetic heart valves can degenerate and fail over time. Repeat surgery as a means of replacement increases morbidity and mortality rates, and some patients are not candidates for reoperation. A newer treatment, percutaneous transcatheter valve-in-valve implantation, might delay or substitute for invasive procedures. We present the case of a 51-year-old woman, a poor candidate for surgery who had prosthetic tricuspid valve degeneration and stenosis. We successfully performed valve-in-valve placement of a Melody valve, using a procedure originally intended to treat pulmonary valve conduit obstruction or regurgitation. To our knowledge, this is among the first case reports to describe the use of the Melody pulmonary valve in transcatheter valve-in-valve replacement for prosthetic tricuspid stenosis that was otherwise not correctable. Additional data and longer follow-up periods are necessary to gain an understanding of ideal indications and selection of patients for the percutaneous transcatheter treatment of tricuspid valve stenosis. PMID:25425984

Snipelisky, David F.; Shapiro, Brian P.

2014-01-01

159

Aortic valve surgery - minimally invasive  

MedlinePLUS

... or repair; Cardiac valvular surgery; Mini-sternotomy; Robotically-assisted endoscopic aortic valve replacement ... type of valve. Biological -- made of human or animal tissue. These valves last 10 to 20 years, ...

160

Medications for Heart Valve Symptoms  

MedlinePLUS

Medications for Heart Valve Symptoms Updated:May 5,2014 How do medications help people with valve problems? People who are ... with heart valve disease may be prescribed a medication to help relieve symptoms and decrease the risk ...

161

Extremum Seeking Control for Soft Landing of an Electromechanical Valve Actuator  

E-print Network

Extremum Seeking Control for Soft Landing of an Electromechanical Valve Actuator Katherine S is the electromechanical valve actuator, recently receiving attention for enabling variable valve timing in internal. This paper presents an extremum seeking controller designed to reduce the magnitude of these impacts. Based

Stefanopoulou, Anna

162

Mitral replacement: clinical experience with a ball-valve prosthesis. Twenty-five years later.  

PubMed Central

The purpose of this report is to review the results of mitral valve replacement since a first report in the Annals of Surgery in 1961, in order to determine the relative importance of new valve designs versus other surgical variables. The continued use of the silastic ball valve in its 1966 configuration (Model 6120), by providing a comparative data base for other new prosthetic valves, allows this analysis. For a valid comparison with the tilting disc (Bjork-Shiley) and the porcine (Hancock and Carpentier-Edwards) valves, only results with the silastic ball valves implanted during comparable time frames should be used. (Formula: see text) Thus, there are no significant differences in the results obtained with the silastic ball valve in time frames comparable to other contemporary valves introduced in the early 1970s. Improved results, therefore, must be non-prosthetic valve related. Images FIG. 1. FIG. 2. FIG. 3. PMID:4037910

Cobanoglu, A; Grunkemeier, G L; Aru, G M; McKinley, C L; Starr, A

1985-01-01

163

The effect of endurance training on resting heart rate variability in sedentary adult males.  

PubMed

Eleven previously sedentary adult males, serving as the experimental (EXP) group [mean (SE) age 36.6 (1.7) years, body mass 87.2 (4.3) kg, body mass index, BMI, 28.4 (1.5) kgm(-2)] participated in a 16-week supervised exercise program (3 days x week(-1), 30 min day(-1), at approximately equal to 80% of heart rate reserve) to determine the temporal effects of a moderate-to-vigorous-intensity exercise program on heart rate variability (HRV). Five sedentary males [mean (SD) age 36.6 (4.2 )years, body mass 83.8 (6.6) kg, BMI 22.8 (1.7) kg x m(-2)] served as non-exercising controls (CON). HRV was measured every 4 weeks from a resting electrocardiogram obtained while subjects paced their breathing at 10 breaths x min(-1) (0.167 Hz). The time-domain measures of HRV recorded were the proportion of adjacent intervals differing by more than 50 ms (pNN50), the root mean square of successive differences (rMSSD), and the standard deviation of the resting interbeat interval. The frequency-domain measures recorded were high (HF) and low (LF) frequency oscillations, as determined using the fast Fourier transform technique. Aerobic capacity (i.e., peak oxygen uptake) increased by 13.8% in EXP (P < 0.001), but did not change in CON. Resting heart rate did not change in either EXP or CON. In EXP, pNN50 at week 12 (P<0.01), rMSSD at weeks 12 (P < 0.01) and 16 (P = 0.05), and HF power at weeks 12 (P < 0.01) and 16 (P = 0.05) were elevated above baseline. Time- and frequency-domain measures of HRV remained unchanged in CON. It is concluded that a moderate-to-vigorous-intensity exercise program produces increases in time- and frequency-domain measures of HRV within 12 weeks. PMID:11606013

Melanson, E L; Freedson, P S

2001-09-01

164

Non-plugging injection valve  

DOEpatents

A valve for injecting fluid into a conduit carrying a slurry subject to separation to form deposits capable of plugging openings into the conduit. The valve comprises a valve body that is sealed to the conduit about an aperture formed through the wall of the conduit to receive the fluid to be injected and the valve member of the valve includes a punch portion that extends through the injection aperture to the flow passage, when the valve is closed, to provide a clear channel into the conduit, when the valve is opened, through deposits which might have formed on portions of the valve adjacent the conduit.

Carey, Jr., Henry S. (Wilsonville, AL)

1985-01-01

165

Preliminary characterization of active MEMS valves.  

SciTech Connect

Partial characterization of a series of electrostatically actuated active microfluidic valves is to be performed. Tests are performed on a series of 24 valves from two different MEMS sets. Focus is on the physical deformation of the structures under variable pressure loadings, as well as voltage levels. Other issues that inhibit proper performance of the valves are observed, addressed and documented as well. Many microfluidic applications have need for the distribution of gases at finely specified pressures and times. To this end a series of electrostatically actuated active valves have been fabricated. Eight separate silicon die are discussed, each with a series of four active valves present. The devices are designed such that the valve boss is held at a ground, with a voltage applied to lower contacts. Resulting electrostatic forces pull the boss down against a series of stops, intended to create a seal as well as prevent accidental shorting of the device. They have been uniquely packaged atop a stack of material layers, which have inlaid channels for application of fluid flow to the backside of the valve. Electrical contact is supplied from the underlying printed circuit board, attached to external supplies and along traces on the silicon. Pressure is supplied from a reservoir of house compressed air, up to 100 Psig. This is routed through a Norgren R07-200-RGKA pressure regulator, rated to 150 Psig. From there flow passes a manually operated ball valve, and to a flow meter. Two flow meters were utilized; initially an Omega FMA1802 rated at 10 sccm, and followed by a Flocat model for higher flow rates up to 100 sccm. An Omega DPG4000-500 pressure gauge produced pressure measurements. Optical measurements were returned via a WYKO Interferometry probe station. This would allow for determination of physical deformations of the device under a variety of voltage and pressure loads. This knowledge could lead to insight as to the failure mechanisms of the device, yielding improvements for subsequent fabrications.

Barnard, Casey Anderson

2010-08-01

166

Vacuum control valve  

Microsoft Academic Search

A vacuum modulating chamber of a vacuum control valve is communicated with a diaphragm chamber of a EGR valve for controlling an amount of exhaust gas to be recirculated into combustion chambers of an engine, so that a modulated negative pressure is applied thereto. The chamber is provided with a diaphragm deflected responding to the negative pressure in the chamber.

M. Naito; K. Itou; K. Tsuzuki; K. Yano

1984-01-01

167

Influence of Acute Normobaric Hypoxia on Physiological Variables and Lactate Turn Point Determination in Trained Men  

PubMed Central

The goal of this study is to evaluate the response of physiological variables to acute normobaric hypoxia compared to normoxia and its influence on the lactate turn point determination according to the three-phase model of energy supply (Phase I: metabolically balanced at muscular level; Phase II: metabolically balanced at systemic level; Phase III: not metabolically balanced) during maximal incremental exercise. Ten physically active (VO2max 3.9 [0.49] lmin-1), healthy men (mean age [SD]: 25.3 [4.6] yrs.), participated in the study. All participants performed two maximal cycle ergometric exercise tests under normoxic as well as hypoxic conditions (FiO2 = 14%). Blood lactate concentration, heart rate, gas exchange data, and power output at maximum and the first and the second lactate turn point (LTP1, LTP2), the heart rate turn point (HRTP) and the first and the second ventilatory turn point (VETP1, VETP2) were determined. Since in normobaric hypoxia absolute power output (P) was reduced at all reference points (max: 314 / 274 W; LTP2: 218 / 184 W; LTP1: 110 / 96 W), as well as VO2max (max: 3.90 / 3.23 lmin-1; LTP2: 2.90 / 2.43 lmin-1; LTP1: 1.66 / 1.52 lmin-1), percentages of Pmax at LTP1, LTP2, HRTP and VETP1, VETP2 were almost identical for hypoxic as well as normoxic conditions. Heart rate was significantly reduced at Pmax in hypoxia (max: 190 / 185 bpm), but no significant differences were found at submaximal control points. Blood lactate concentration was not different at maximum, and all reference points in both conditions. Respiratory exchange ratio (RER) (max: 1.28 / 1.08; LTP2: 1.13 / 0.98) and ventilatory equivalents for O2 (max: 43.4 / 34.0; LTP2: 32.1 / 25.4) and CO2 (max: 34.1 / 31.6; LTP2: 29.1 / 26.1) were significantly higher at some reference points in hypoxia. Significant correlations were found between LTP1 and VETP1 (r = 0.778; p < 0.01), LTP2 and HRTP (r = 0.828; p < 0.01) and VETP2 (r = 0.948; p < 0.01) for power output for both conditions. We conclude that the lactate turn point determination according to the three-phase-model of energy supply is valid in normobaric, normoxic as well as hypoxic conditions. The turn points for La, HR, and VE were reproducible among both conditions, but shifted left to lower workloads. The lactate turn point determination may therefore be used for the prescription of exercise performance in both environments. Key Points The lactate turn point concept can be used for performance testing in normoxic and hypoxic conditions The better the performance of the athletes the higher is the effect of hypoxia The HRTP and LTP2 are strongly correlated that allows a simple performance testing using heart rate measures only.

Ofner, Michael; Wonisch, Manfred; Frei, Mario; Tschakert, Gerhard; Domej, Wolfgang; Krpfl, Julia M.; Peter, Hofmann

2014-01-01

168

JAMA Patient Page: Heart Valve Infections  

MedlinePLUS

Cross Section of Heart With Valve Replacement Prosthetic Aortic Valve Right Atrium Right Ventricle Tricuspid Valve Left Atrium Mitral Valve Left Ventricle Aorta Vegetations Complications Associated With Heart Valve Infections Emboli Abscess Regurgitation ...

169

Valve disease in pregnancy.  

PubMed

Maternal cardiac disease is a major cause of non-obstetric morbidity and accounts for 10-25% of maternal mortality. Valvular heart disease may result from congenital abnormalities or acquired lesions, some of which may involve more than one valve. Maternal and fetal risks in pregnant patients with valve disease vary according to the type and severity of the valve lesion along with resulting abnormalities of functional capacity, left ventricular function, and pulmonary artery pressure. Certain high-risk conditions are considered contraindications to pregnancy, while others may be successfully managed with observation, medications, and, in refractory cases, surgical intervention. Communication between the patient?s obstetrician, maternal-fetal medicine specialist, obstetrical anesthesiologist, and cardiologist is critical in managing a pregnancy with underlying maternal cardiac disease. The management of the various types of valve diseases in pregnancy will be reviewed here, along with a discussion of related complications including mechanical prosthetic valves and infective endocarditis. PMID:25037517

Pessel, Cara; Bonanno, Clarissa

2014-08-01

170

Boston Scientific Lotus valve.  

PubMed

As a result of recent randomised controlled trials and registry observations, transcatheter aortic valve replacement (TAVR) enjoys growing appeal for the treatment of patients at high or extreme risk from surgical aortic valve replacement. However, the current technologies and techniques have important limitations, including risk of stroke, vascular complications and paravalvular aortic regurgitation, which may in turn influence survival. While careful patient selection and screening may improve outcomes, new valve designs and iterations are required. The Lotus aortic valve replacement system is a new fully repositionable device designed to facilitate more precise delivery and minimise paravalvular regurgitation. The safety and efficacy of the Lotus valve are being studied systematically in the REPRISE clinical trial programme. PMID:22995115

Meredith, Ian T; Hood, Kristin L; Haratani, Nicole; Allocco, Dominic J; Dawkins, Keith D

2012-09-01

171

Challenging transfemoral valve-in-valve implantation in a degenerated stentless bioprosthetic aortic valve.  

PubMed

Bioprosthetic heart valves are often preferred over mechanical valves as they may preclude the need for anticoagulation. Reoperation is the standard treatment for structural failure of bioprosthetic valves; however, it carries significant risk especially in inoperable elderly patients. Valve-in-valve (ViV) transcatheter aortic valve replacement (TAVR) seems to be an effective and promising procedure in patients with degenerated bioprosthetic aortic valves avoiding the risks associated with the use of cardioplegia and redo cardiac surgery. We report an interesting case of a high-risk 74-year-old patient with a degenerated Sorin Freedom Solo stentless valve treated successfully with ViV TAVR. PMID:25091103

Halapas, A; Chrissoheris, M; Spargias, Konstantinos

2014-08-01

172

Transcatheter valve-in-valve implantation for degenerated mitral valve bioprosthesis under 3D echocardiographic guidance.  

PubMed

Transcatheter mitral valve-in-valve replacement is increasingly being performed as operator and center experience in transcatheter valve replacement technology and techniques have accrued. Complications, such as valve embolization and paravalvular regurgitation, still occur and relate to valve deployment. The use of novel imaging techniques, such as 3D echocardiography, allows for better differentiation of cardiac structures and appropriate positioning of the transcatheter valve using well-visualized anatomical landmarks. Here the authors describe in images and video the use of 3D echocardiography for deployment of a mitral valve-in-valve. PMID:25134981

Lerakis, Stamatios; Hayek, Salim S; Thourani, Vinod; Babaliaros, Vasilis

2014-09-01

173

Design and dynamic simulation of a fixed pitch 56 kW wind turbine drive train with a continuously variable transmission  

NASA Technical Reports Server (NTRS)

The dynamic analysis of a horizontal axis fixed pitch wind turbine generator (WTG) rated at 56 kW is discussed. A mechanical Continuously Variable Transmission (CVT) was incorporated in the drive train to provide variable speed operation capability. One goal of the dynamic analysis was to determine if variable speed operation, by means of a mechanical CVT, is capable of capturing the transient power in the WTG/wind environment. Another goal was to determine the extent of power regulation possible with CVT operation.

Gallo, C.; Kasuba, R.; Pintz, A.; Spring, J.

1986-01-01

174

Dual valve plate two-way pressure relief valve  

NASA Astrophysics Data System (ADS)

This patent application discloses a two-way valve which includes dual valve plates to be positioned between first and second chambers having varying pressure therein, to relieve excess pressure in either chamber by permitting fluid flow from one chamber to the other. The valve includes a body portion having disposed therein dual valve plates. In the equilibrium state, the first valve plate is spring biased against the valve body in the direction of the first chamber to seal off any flow through the valve. The second valve plate is separately spring biased against the first valve plate in the direction of the second chamber, sealing off flow between the valve plates. When the pressure of the first chamber is greater than the pressure of the second chamber by a predetermined amount, the first and second valve plates move away from the valve body permitting fluid flow from the first chamber to the second chamber. When the pressure of the second chamber exerted on the second valve plate through apertures in the first valve plate is greater than the pressure of the first chamber by a predetermined amount, the second valve plate moves away from the face of the first valve plate permitting fluid flow from the second chamber to the first chamber.

Angeli, Robert J.

1993-02-01

175

Exercise Training Improves Heart Rate Variability in Older Patients with Heart Failure: A Randomized, Controlled, Single-Blinded Trial  

PubMed Central

Background Reduced heart rate variability (HRV) in older patients with heart failure (HF) is common and indicates poor prognosis. Exercise training (ET) has been shown to improve HRV in younger patients with HF. However the effect of ET on HRV in older patients with HF is not known. Methods and Results Sixty-six participants (36% males), age 695 years, with HF and both preserved ejection fraction (HFPEF) and reduced ejection fraction (HFREF), were randomly assigned to 16 weeks of supervised ET (ET group) versus attention-control (AC group). Two HRV parameters (the standard deviation of all normal RR intervals (SDNN) and the root mean square of successive differences in normal RR intervals (RMSSD)) were measured at baseline and after completion of the study. When compared with the AC group, the ET group had a significantly greater increase in both SDNN (15.46 5.02 ms in ET versus 2.37 2.13 ms in AC, P = 0.016), and RMSSD (17.53 7.83 ms in ET versus 1.69 2.63 ms in AC, P = 0.003). This increase was seen in both genders and HF categories. Conclusion ET improves HRV in older patients with both HFREF and HFPEF. PMID:22536936

Murad, Khalil; Brubaker, Peter H.; Fitzgerald, David M; Morgan, Timothy M; Goff, David C; Soliman, Elsayed Z; Eggebeen, Joel D; Kitzman, Dalane W

2012-01-01

176

Hypergraphs for the analysis of complex mechanisms comprising planetary gear trains and other variable or fixed transmissions  

Microsoft Academic Search

This article presents a methodology for the kinematic analysis of complex gear trains comprised of planetary gear trains. It is based on the utilisation of hypergraphs, which provides a novel view into the analysis of this type of power trains. The hypergraphs are used to aid in the understanding of the inter-relation between the various branches of the mechanism and

J. R. Gom Ayats; U. Diego-Ayala; J. Minguella Canela; F. Fenollosa; J. Vivancos

177

Pressure regulating valve controller  

SciTech Connect

In an aircraft cabin air conditioning system comprising a pair of air cycle refrigeration systems which provide chilled air to the cabin, airflow through the air cycle refrigeration systems being controllable by a pair of pressure regulating valves, each of the pressure regulating valves being disposed in a corresponding main airflow conduit and operated by a corresponding pneumatic valve actuator, the improvement is described by: one of the pneumatic valve actuators associated with one of the pressure regulating valves being operated by a controller comprising: a main servo conduit communicating with one of the main airflow conduits and the pneumatic valve actuator for channeling pneumatic pressure thereto from the main airflow; a first pressure regulator communicating with the main servo conduit for continuously adjusting pneumatic pressure therewithin in response to ram air temperature; a second pressure regulator communicating with the main servo conduit for providing step function adjustment in pneumatic pressure; and means communicating with the main servo conduit for overriding the second pressure regulator to effect partial closing of the one pressure regulating valve despite the deactivation of the air cycle system.

Goodman, R.B.

1988-04-05

178

Risks for Heart Valve Problems  

MedlinePLUS

... a more common problem. As we age, our heart valves can become lined with calcium deposits that cause the valve flaps to thicken and become stiffer. ... increase a persons risk for sudden death or cause rapid development of problems in ... like a bicuspid aortic valve, mitral valve prolapse or a mild form of ...

179

Engineering the Heart: Heart Valves  

NSDL National Science Digital Library

Students learn how healthy human heart valves function and the different diseases that can affect heart valves. They also learn about devices and procedures that biomedical engineers have designed to help people with damaged or diseased heart valves. Students learn about the pros and cons of different materials and how doctors choose which engineered artificial heart valves are appropriate for certain people.

Integrated Teaching And Learning Program

180

Electric exhaust gas recirculation valve  

Microsoft Academic Search

An electrically actuated EGR valve is described for controlling EGR gases in response to electric signals from a computer, the EGR valve comprising: a valve housing having an exhaust gas inlet port for passage of exhaust gases; an exhaust gas outlet port; an exhaust gas passage extending between; poppet valve means for selectively opening and closing exhaust gas passage, the

Akagi

1987-01-01

181

Aortic valve disease.  

PubMed

Aortic valve disease is common and has significant impact on prognosis and quality of life. In this educational review, we cover the pathophysiology, presentation and assessment of aortic stenosis (AS) and aortic regurgitation (AR), including the role of imaging modalities beyond echocardiography. We review current treatment strategies and emphasise the use and indications for transcatheter aortic valve implantation (TAVI) in view of recent data highlighting its emergence as a novel treatment option for patients with AS, who are unsuitable for conventional aortic valve replacement (AVR). We also describe novel surgical approaches for AR and potential future strategies for percutaneous intervention. PMID:24898790

Rayner, J; Coffey, S; Newton, J; Prendergast, B D

2014-10-01

182

The effects of exercise training on maximum aerobic capacity, resting heart rate, blood pressure and anthropometric variables of postmenopausal women with breast cancer  

PubMed Central

BACKGROUND: The aim of this study was to investigate the effects of exercise training on maximum aerobic capacity, resting heart rate (RHR), blood pressure and anthropometric variables of postmenopausal women with breast cancer. METHODS: Twenty nine women with breast cancer who received surgery, chemotherapy and radiotherapy with current hormone therapy were divided into two groups; intervention and control. Subjects in the intervention group performed 15 weeks combination exercise training including walking for 25 to 45 minutes (2 sessions per week) and resistance training for 60 minutes (2 sessions per week that were different from walking days). In pre and post tests, VO2max, RHR, blood pressure, body weight, body mass index (BMI) and waist to hip ratio (WHR) were measured in both groups. Data was analyzed using analysis of covariance (ANCOVA). RESULTS: Significant differences were observed for VO 2max, RHR, body weight, BMI and WHR between intervention and control groups after 15 weeks (p < 0.05). In fact, exercise training had positive effects on the VO 2max, RHR, body weight, BMI and WHR in postmenopausal women with breast cancer. No significant different was found for blood pressure between two groups (p > 0.05). CONCLUSIONS: It can be concluded that exercise training may improve maximum aerobic capacity, RHR and anthropometric variables in postmenopausal women with breast cancer. PMID:21526063

Rahnama, Nader; Nouri, Reza; Rahmaninia, Farhad; Damirchi, Arsalan; Emami, Hamid

2010-01-01

183

Effects of additional repeated sprint training during preseason on performance, heart rate variability, and stress symptoms in futsal players: a randomized controlled trial.  

PubMed

Soares-Caldeira, LF, de Souza, EA, de Freitas, VH, de Moraes, SMF, Leicht, AS, and Nakamura, FY. Effects of additional repeated sprint training during preseason on performance, heart rate variability, and stress symptoms in futsal players: A randomized controlled trial. J Strength Cond Res 28(10): 2815-2826, 2014-The aim of this study was to investigate whether supplementing regular preseason futsal training with weekly sessions of repeated sprints (RS) training would have positive effects on repeated sprint ability (RSA) and field test performance. Thirteen players from a professional futsal team (22.6 6.7 years, 72.8 8.7 kg, 173.2 6.2 cm) were divided randomly into 2 groups (AddT: n = 6 and normal training group: n = 7). Both groups performed a RSA test, Yo-Yo intermittent recovery test level 1 (YoYo IR1), squat (SJ) and countermovement jumps (CMJ), body composition, and heart rate variability (HRV) measures at rest before and after 4 weeks of preseason training. Athletes weekly stress symptoms were recorded by psychometric responses using the Daily Analysis of Life Demands for Athletes questionnaire and subjective ratings of well-being scale, respectively. The daily training load (arbitrary units) was assessed using the session of rating perceived exertion method. After the preseason training, there were no significant changes for body composition, SJ, CMJ, and RSAbest. The YoYo IR1, RSAmean, RSAworst, and RSAdecreament were significantly improved for both groups (p ? 0.05). The HRV parameters improved significantly within both groups (p ? 0.05) except for high frequency (HF, absolute and normalized units, [n.u.]), low frequency (LF) (n.u.), and the LF/HF ratio. A moderate effect size for the AddT group was observed for resting heart rate and several HRV measures. Training load and psychometric responses were similar between both groups. Additional RS training resulted in slightly greater positive changes for vagal-related HRV with similar improvements in performance and training stress during the preseason training in futsal players. PMID:24662230

Soares-Caldeira, Lcio F; de Souza, Eberton A; de Freitas, Victor H; de Moraes, Solange M F; Leicht, Anthony S; Nakamura, Fbio Y

2014-10-01

184

Long life valve design concepts  

NASA Technical Reports Server (NTRS)

Valve concept evaluation, final candidate selection, design, manufacture, and demonstration testing of a pneumatically actuated 10-inch hybrid poppet butterfly shutoff valve are presented. Conclusions and recommendations regarding those valve characteristics and features which would serve to guide in the formulation of future valve procurements are discussed. The pertinent design goals were temperature range of plus 200 to minus 423 F, valve inlet pressure 35 psia, actuation pressure 750 psia, main seal leakage 3 x 0.00001 sccs at 35 psia valve inlet pressure, and a storage and operating life of 10 years. The valve was designed to be compatible with RP-1, propane, LH2, LO2, He, and N2.

Jones, J. R.; Hall, A. H., Jr.

1975-01-01

185

The operation of LPG relief valves  

SciTech Connect

As stipulated by NFPA 58, all LPG storage containers must be equipped with one or more pressure relief devices. These devices are sized to prevent rupture of a normally charged container when exposed to fire. This paper describes in detail the functioning of the spring-loaded relief valve. The author discusses how the venting of LPGs can produce unacceptable risks and how training is a necessary part of controlling such a situation.

Stannard, J.H. Jr

1989-11-01

186

Improve safety with pilot operated relief valves  

SciTech Connect

A weakness inherent in balanced bellows pressure relief valves (PRVs) that can cause premature failure can be avoided by using pilot operated PRVs as an alternative. Now better able to handle adverse service conditions, pilot operated PRVs are suitable for a wide range of gas, liquid and mixed-phase services. Traditionally, however, balanced bellows PRVs have been applied as overpressure protection for three notable reasons: a constant PRV set pressure with the presence of variable, superimposed back pressure (at the PRV outlet prior to its opening); valve stability and adequate capacity when built-up back pressure (at the PRV outlet during its relief cycle) exceeds 10%; and spring and guided parts barriered from the process fluid. With these benefits in mind, balanced bellows PRVs have been generally adapted by many hydrocarbon processing companies that have experienced costly, and often dangerous, premature bellows failures. Corrosion, valve instability and/or bellows flutter are causes of these failures.

Emerson, G. [Anderson, Greenwood and Co., Stafford, TX (United States)

1996-10-01

187

Mitral Valve Prolapse  

MedlinePLUS

... are "floppy" and don't close tightly. Most people who have the condition are born with it. ... dizziness, or anxiety Migraine headaches Chest discomfort Most people who have mitral valve prolapse (MVP) don't ...

188

Mitral Valve Prolapse.  

ERIC Educational Resources Information Center

Mitral valve prolapse is the most common heart disease seen in college and university health services. It underlies most arrhythmia and many chest complaints. Activity and exercise restrictions are usually unnecessary. (Author/CJ)

Bergy, Gordon G.

1980-01-01

189

Mitral Valve Prolapse  

MedlinePLUS

... are connected to wires and a machine that records the electricity coming from your heart. The machine ... you can still be the MVP (most valuable player) even if you have MVP (mitral valve prolapse)! ...

190

Valve-in-valve implantation for aortic annular rupture complicating transcatheter aortic valve replacement (TAVR).  

PubMed

An 83-year-old woman with multiple comorbidities and severe aortic stenosis presented with recurrent pulmonary edema. In light of her high surgical risk, a percutaneous strategy for her aortic stenosis was decided. Transcatheter aortic valve replacement using a balloon-expandable Edwards Sapien XT valve was performed under rapid ventricular pacing. Soon after valve deployment, the patient went into hemodynamic collapse due to annular root rupture with pericardial tamponade, necessitating urgent pericardial decompression. Using a valve-in-valve technique, with the deployment of a second Edward Sapien XT valve inside the first valve, the annular root rupture was successfully sealed leading to hemodynamic recovery. PMID:23913607

Yu, Young; Vallely, Michael; Ng, Martin K C

2013-08-01

191

Electronic feedback EGR valve  

SciTech Connect

An improved EGR valve controller is described which consists of: (A) body means defining an exhaust gas recirculation passage having an inlet, an outlet and a valve seat disposed in the passage intermediate the inlet and the outlet; (B) a valve member disposed in the EGR passage, the valve member moveable with respect to the valve seat for controlling flow through the passage; (C) pressure responsive means defining in cooperation with the body means a vacuum signal chamber; (D) means defining a vacuum connector having a port communicating with the vacuum signal chamber, the connector adapted for connection to a vacuum source; (E) actuator means operatively interconnecting the pressure responsive means and the valve member for effecting movement of the latter in response to pressure changes in the vacuum chamber; (F) means defining an EGR flow limiting orifice in the EGR passage upstream of the valve seat; (G) means defining a pressure tap in the EGR passage intermediate the valve seat and the flow limiting orifice; (H) pressure transducer means having a sensing port and mounted on the body means remote from the EGR passage with the sensing port vertically at a level above the pressure tap when the controller is installed on an engine; (I) conduit means extending externally of the body means and interconnecting the pressure tap and the transducer sensing port the conduit means including a section disposed externally of the body means and operative to thermally isolate the transducer port from the pressure top. The transducer means is operative to emit an electrical signal having certain characteristics indicative of the pressure sensed in the tap.

Kenny, A.A.; Sokalski, R.G.; Egle, L.E.; Stahly, D.C.

1986-01-28

192

Liquid blocking check valve  

DOEpatents

A liquid blocking check valve useful particularly in a pneumatic system utilizing a pressurized liquid fill chamber. The valve includes a floatable ball disposed within a housing defining a chamber. The housing is provided with an inlet aperture disposed in the top of said chamber, and an outlet aperture disposed in the bottom of said chamber in an offset relation to said inlet aperture and in communication with a cutaway side wall section of said housing.

Merrill, John T. (Pleasant Hill, CA)

1984-01-01

193

[Transcatheter aortic valve replacement].  

PubMed

While transcatheter aortic valve replacement( TAVR) has spread rapidly all over the world for highrisk patients with severe aortic stenosis (AS), SAPIEN XT was approved in Japan in October 2013. Since that, approximately 400 TAVR cases were performed in Japan. In our institute, we have performed 164 cases since first case in Japan in 2009 and have achieved satisfactory early results(30-day mortality:1.2%). At the same time, however, simultaneously various TAVR-related complications including a paravalvular leak, stroke, vascular complications, and coronary obstruction were observed. A reduction in the incidence and severity of these complications had led technical improvements in various new devices(2nd generation TAVR device such as the SAPIEN 3, ACURATE, and JenaValve) and in implantation techniques including repositioning/recapturing features, paravalvular sealing technologies, and prevention of coronary obstruction. Furthermore, there is also increasing experience with special indications for TAVR such as pure aortic valve insufficiency or valve-in-valve techniques. Currently, an increasing number of publications of midterm results demonstrate good prosthetic valve function and durability, with good quality of life and low morbidity after TAVR. There are also some randomized trials such as PARTNER 2 or SURTAVI to investigate potential benefits of TAVR for intermediate-risk patients. These improvements in the TAVR devices promises the expansion of TAVR towards the treatment of lower-risk patients in the near future. PMID:25138938

Sawa, Yoshiki

2014-07-01

194

Transcatheter aortic valve implantation.  

PubMed

Transcatheter aortic valve implantation (TAVI) was introduced experimentally in 1989, based on a newly developed heart valve prosthesis - the stentvalve. The valve was invented by a Danish cardiologist named Henning Rud Andersen. The new valve was revolutionary. It was foldable and could be inserted via a catheter through an artery in the groin, without the need for heart lung machine. This allowed for a new valve implantation technique, much less invasive than conventional surgical aortic valve replacement (SAVR). Surgical aortic valve replacement is safe and improves symptoms along with survival. However, up to 1/3 of patients with aortic valve stenosis cannot complete the procedure due to frailty. The catheter technique was hoped to provide a new treatment option for these patients. The first human case was in 2002, but more widespread clinical use did not begin until 2006-2010. Today, in 2011, more than 40,000 valves have been implanted worldwide. Initially, because of the experimental character of the procedure, TAVI was reserved for patients who could not undergo SAVR due to high risk. The results in this group of patients were promising. The procedural safety was acceptable, and the patients experienced significant improvements in their symptoms. Three of the papers in this PhD-thesis are based on the outcome of TAVI at Skejby Hospital, in this high-risk population [I, II and IV]. Along with other international publications, they support TAVI as being superior to standard medical treatment, despite a high risk of prosthetic regurgitation. These results only apply to high-risk patients, who cannot undergo SAVR. The main purpose of this PhD study has been to investigate the quality of TAVI compared to SAVR, in order to define the indications for this new procedure. The article attached [V] describes a prospective clinical randomised controlled trial, between TAVI to SAVR in surgically amenable patients over 75 years of age with isolated aortic valve stenosis. The study was terminated prematurely, as patients undergoing TAVI showed a statistically non-significant trend towards more complications than SAVR patients. Although non-significant the study was closed for ethical reasons. At present, scientific evidence supports TAVI as being superior to standard medical treatment, in patients who cannot undergo SAVR due to high- predicted risk. However, in patients who are surgically amenable, current publications suggest that TAVI using presently available devices is not competitive to SAVR, with regards to procedural safety and outcome. PMID:23290293

Nielsen, Hans Henrik Mller

2012-12-01

195

Cardiac energetics analysis after aortic valve replacement with 16-mm ATS mechanical valve.  

PubMed

The 16-mm ATS mechanical valve is one of the smallest prosthetic valves used for aortic valve replacement (AVR) in patients with a very small aortic annulus, and its clinical outcomes are reportedly satisfactory. Here, we analyzed the left ventricular (LV) performance after AVR with the 16-mm ATS mechanical valve, based on the concept of cardiac energetics analysis. Eleven patients who underwent AVR with the 16-mm ATS mechanical valve were enrolled in this study. All underwent echocardiographic examination at three time points: before AVR, approximately 1month after AVR, and approximately 1year after AVR. LV contractility (end-systolic elastance [Ees]), afterload (effective arterial elastance [Ea]), and efficiency (ventriculoarterial coupling [Ea/Ees] and the stroke work to pressure-volume area ratio [SW/PVA]) were noninvasively measured by echocardiographic data and blood pressure measurement. Ees transiently decreased after AVR and then recovered to the pre-AVR level at the one-year follow-up. Ea significantly decreased in a stepwise manner. Consequently, Ea/Ees and SW/PVA were also significantly improved at the one-year follow-up compared with those before AVR. The midterm LV performance after AVR with the 16-mm ATS mechanical valve was satisfactory. AVR with the 16-mm ATS mechanical valve is validated as an effective treatment for patients with a very small aortic annulus. The cardiac energetics variables, coupling with the conventional hemodynamic variables, can contribute to a better understanding of the patients' clinical conditions, and those may serve as promising indices of the cardiac function. PMID:24859744

Ushijima, Tomoki; Tanoue, Yoshihisa; Uchida, Takayuki; Matsuyama, Sho; Matsumoto, Takashi; Tominaga, Ryuji

2014-09-01

196

Safety check valve  

SciTech Connect

This patent describes a safety check valve, for use with a pumping unit for petroleum fluids, the pumping unit including a polished rod and a stuffing box. It comprises: a valve housing having upper and lower ends and a central bore extending between the upper and lower ends and adapted to have the polished rod pass through the central bore; a ball seating surface associated with the central bore; a non-spring bias ball; a ball housing for the ball and associated with the valve housing; and means for moving the ball from the ball housing into the central bore upon the polished rod not being disposed in the central bore, including a ball receiving cavity associated with the ball housing, the ball hoising having first and second ends, the first end of the ball housing being in communication with the central bore of the valve housing, the second end being closed; the ball receiving cavity having a ball support surface upon which the ball may rest, when the ball is disposed in the ball receiving cavity, the ball support surface sloping downwardly toward the first end of the ball housing, whereby if the polished rod is not disposed within the central bore of the valve housing, the ball moves down the ball support surface, under the force of gravity, from the ball receiving cavity into the central bore and seats on the ball seating surface.

Spears, H.L.

1992-02-11

197

Check valves aging assessment  

SciTech Connect

In support of the NRC Nuclear Plant Aging Research (NPAR) program, the Oak Ridge National Laboratory (ORNL) has carried out an assessment of several check value diagnostic monitoring methods, in particular, those based on measurements of acoustic emission, ultrasonics, and magnetic flux. The evaluations have focussed on the capabilities of each method to provide information useful in determining check valve aging and service wear effects, check valve failures, and undesirable operating modes. This paper describes the benefits and limitations associated with each method and includes recent laboratory and field test data, including data obtained from the vendors who recently participated in a comprehensive series of tests directed by a nuclear industry users group. In addition, as part of the ORNL Advanced Diagnostic Engineering Research and Development Center (ADEC), two novel nonintrusive monitoring methods were developed that provide several unique capabilities. These methods, based on external ac- an dc-magnetic monitoring are also described. None of the examined methods could, by themselves, monitor both the instantaneous position and motion of check valve internals and valve leakage; however, the combination of acoustic emission monitoring with one of the other methods provides the means to determine vital check valve operational information.

Haynes, H.D.

1991-01-01

198

Understanding Heart Valve Problems and Causes  

MedlinePLUS

Understanding Heart Valve Problems and Causes Updated:May 6,2014 Many heart valve problems are first identified by the ... Congenital Heart Defect See all of our brochures Heart Valve Problems and Disease Home About Heart Valves ...

199

Application of diagnostics to determine motor-operated valve operational readiness  

Microsoft Academic Search

ORNL has been carrying out an aging assessment of motor-operated valves (MOVs) with the primary objective of recommending diagnostic methods for detecting and trending aging. As a result of experimental investigations at ORNL, it was discovered that the motor current during a valve stroke was a very useful diagnostic parameter for detecting and trending many MOV drive train load variations.

Eissenberg

1986-01-01

200

Self-compassion training modulates alpha-amylase, heart rate variability, and subjective responses to social evaluative threat in women.  

PubMed

A growing body of research has revealed that social evaluative stressors trigger biological and psychological responses that in chronic forms have been linked to aging and disease. Recent research suggests that self-compassion may protect the self from typical defensive responses to evaluation. We investigated whether brief training in self-compassion moderated biopsychological responses to the Trier Social Stress Test (TSST) in women. Compared to attention (placebo) and no-training control conditions, brief self-compassion training diminished sympathetic (salivary alpha-amylase), cardiac parasympathetic, and subjective anxiety responses, though not HPA-axis (salivary cortisol) responses to the TSST. Self-compassion training also led to greater self-compassion under threat relative to the control groups. In that social stress pervades modern life, self-compassion represents a promising approach to diminishing its potentially negative psychological and biological effects. PMID:24636501

Arch, Joanna J; Brown, Kirk Warren; Dean, Derek J; Landy, Lauren N; Brown, Kimberley D; Laudenslager, Mark L

2014-04-01

201

83. Interior of 42 valve house; the motor and valve ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

83. Interior of 4-2 valve house; the motor and valve mechanism is identical to that in the 4-1 valve house. Photo by Jet Lowe, HAER, 1989. - Puget Sound Power & Light Company, White River Hydroelectric Project, 600 North River Avenue, Dieringer, Pierce County, WA

202

81. View of 41 valve house (right) and 42 valve ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

81. View of 4-1 valve house (right) and 4-2 valve house (left); in the foreground is penstock which extends from Penstock No. 1 to the 4-1 valve house; looking south. Photo by Jet Lowe, HAER, 1989. - Puget Sound Power & Light Company, White River Hydroelectric Project, 600 North River Avenue, Dieringer, Pierce County, WA

203

Vacuum control valve  

SciTech Connect

A vacuum modulating chamber of a vacuum control valve is communicated with a diaphragm chamber of a EGR valve for controlling an amount of exhaust gas to be recirculated into combustion chambers of an engine, so that a modulated negative pressure is applied thereto. The chamber is provided with a diaphragm deflected responding to the negative pressure in the chamber. The vacuum control valve is further provided with a cam member and a spring which urges the diaphragm in one direction so as to change a value at which the pressure in the vacuum modulating chamber is controlled. A push rod is movably held by a cam follower and another spring is provided for urging the push rod in the above direction. The spring force of the other spring is applied to the diaphragm, when a rotational angle of the cam member exceeds a predetermined angle, so that the negative pressure is changed rapidly.

Naito, M.; Itou, K.; Tsuzuki, K.; Yano, K.

1984-04-03

204

Magnetostrictive valve assembly  

NASA Technical Reports Server (NTRS)

A magnetostrictive valve assembly includes a housing that defines a passage with a seat being formed therein. A magnetically-biased and axially-compressed magnetostrictive assembly slidingly fitted in the passage is configured as a hollow and open-ended conduit adapted to support a flow of a fluid therethrough. Current-carrying coil(s) disposed about the passage in the region of the magnetostrictive assembly generate a magnetic field in the passage when current flows through the coil(s). A hollow valve body with side ports is coupled on one end thereof to an axial end of the magnetostrictive assembly. The other end of the valve body is designed to seal with the seat formed in the housing's passage when brought into contact therewith.

Richard, James A. (Inventor)

2008-01-01

205

Living with Mitral Valve Prolapse  

MedlinePLUS

... Tumblr. Share this page from the NHLBI on Twitter. Living With Mitral Valve Prolapse Most people who have mitral valve prolapse (MVP) have no symptoms or related problems, need no treatment, and are able to lead ...

206

Electric exhaust gas recirculation valve  

SciTech Connect

An electrically actuated EGR valve is described for controlling EGR gases in response to electric signals from a computer, the EGR valve comprising: a valve housing having an exhaust gas inlet port for passage of exhaust gases; an exhaust gas outlet port; an exhaust gas passage extending between; poppet valve means for selectively opening and closing exhaust gas passage, the poppet valve means including a valve rod slidably supported for movement in a linear direction in the housing; an electric step motor responsive to electric pulse signals and including output means for directly contacting and moving the valve rod; and a motor casing secured to the valve housing with an insulating element. The step motor is isolated from heat from the exhaust gases and motor casing includes apertures formed where air may be circulated into the motor casing to further thermally isolate the step motor.

Akagi, M.

1987-06-23

207

Locking apparatus for gate valves  

DOEpatents

A locking apparatus for fluid operated valves having a piston connected to the valve actuator which moves in response to applied pressure within a cylinder housing having a cylinder head, a catch block is secured to the piston, and the cylinder head incorporates a catch pin. Pressure applied to the cylinder to open the valve moves the piston adjacent to the cylinder head where the catch pin automatically engages the catch block preventing futher movement of the piston or premature closure of the valve. Application of pressure to the cylinder to close the valve, retracts the catch pin, allowing the valve to close. Included are one or more selector valves, for selecting pressure application to other apparatus depending on the gate valve position, open or closed, protecting such apparatus from damage due to premature closing caused by pressure loss or operational error.

Fabyan, Joseph (Livermore, CA); Williams, Carl W. (Manteca, CA)

1988-01-01

208

Energy Savings Potential of Process Control Valve Replacement  

E-print Network

variable pressure drop element in the process piping system. The hydraulic system characteristics are then modified to suit the desired control conditions by throttling the control valve flow area to increase or decrease the pressure drop across... the valve. This control philosophy is very effective, but is implemented by creating an energy loss in the piping system to balance the unnecessary energy being delivered by the constant speed pump. HYDRAULIC SYSTEM ANALYSIS Figure I shows the flow (Q...

Holzenthal, L. Jr.

209

[Imaging in mitral valve interventions].  

PubMed

Percutaneous cardiac valve interventions have significantly extended the therapeutic options for patients with diseased cardiac valves. Technical miniaturization and major advancements in cardiac imaging techniques are the cornerstones of this successful development. Regarding mitral valve interventions periprocedural echocardiography in particular is of uttermost importance. This review describes the state of the art echocardiographic imaging techniques focusing on the clinically established mitral valve interventions: MitraClip implantation, percutaneous closure of periprosthetic leaks and mitral balloon valvuloplasty. PMID:23838846

Kreidel, F; Alessandrini, H; Frerker, C; Thielsen, T; Schfer, U; Kuck, K H

2013-08-01

210

Precise-Conductance Valve Insert  

NASA Technical Reports Server (NTRS)

Valve modification provides two operating modes fully open and small, precise leak. Copper insert with radially oriented holes allows small, controllable, precise effusion rate when valve closed or nearly unobstructed flow when valve open. Numerous applications in surface physics, vacuum physics, materials science, gas kinetics, thin films, and other areas of research requiring measured flows of gas into or out of system.

Outlaw, R. A.; Hoyt, R. F.

1986-01-01

211

Heart rate recovery and variability following combined aerobic and resistance exercise training in adults with and without Down syndrome.  

PubMed

Persons with Down syndrome (DS) are at high risk for cardiovascular morbidity and mortality, and there is compelling evidence of autonomic dysfunction in these individuals. The main purpose of this study was to determine whether a combined aerobic and resistance exercise intervention produces similar results in cardiac autonomic function between adults with and without DS. Twenty-five participants (13 DS; 12 non-DS), aged 27-50 years, were included. Aerobic training was performed 3 days/week for 30 min at 65-85% of peak oxygen uptake (VO(2peak)). Resistance training was prescribed for 2 days/week and consisted of two rotations in a circuit of 9 exercises at 12-repetition-maximum. There was a significant improvement in the VO(2peak) and muscle strength of participants with and without DS after training. Heart rate recovery improved at 1 min post-exercise, but only in participants with DS. Both groups of participants exhibited a similar increase in normalized high frequency power and of decrease in normalized low frequency power after training. Therefore, 12 weeks of exercise training enhanced the heart rate recovery in adults with DS, but not in those without DS. Contrasting, the intervention elicited similar gains between groups for cardiovagal modulation. PMID:23006505

Mendonca, Goncalo V; Pereira, Fernando D; Fernhall, Bo

2013-01-01

212

Development of a high-performance TiAl exhaust valve  

SciTech Connect

A new high-performance and lightweight TiAl intermetallic compound exhaust valve has been developed. The TiAl valve can improve power output and fuel economy by contributing higher engine speeds and a reduction in valve train friction. It was achieved by developing A Ti-33.5Al-0.5Si-1Nb-0.5Cr (mass %) intermetallic compound, a precision casting method for TiAl that provides a low-cost, high-quality process, and a plasma carburizing technique for assuring good wear resistance on the valve stem end, stem and face.

Maki, Kunio; Ehira, Atsushi; Sayashi, Mamoru; Sasaki, Toru; Noda, Toshiharu; Okabe, Michio; Isobe, Susumu

1996-09-01

213

Valve for gas centrifuges  

DOEpatents

The invention is pneumatically operated valve assembly for simulatenously (1) closing gas-transfer lines connected to a gas centrifuge or the like and (2) establishing a recycle path between two on the lines so closed. The value assembly is especially designed to be compact, fast-acting, reliable, and comparatively inexpensive. It provides large reductions in capital costs for gas-centrifuge cascades.

Hahs, C.A.; Rurbage, C.H.

1982-03-17

214

Heart valve surgery - discharge  

MedlinePLUS

... surgery to repair or replace one of your heart valves. Your surgery may have been done through a large incision ( ... 118:e523-e661. Fullerton DA, Harken AH. Acquired heart disease: ... . 19th ed. Philadelphia, Pa: Saunders Elsevier; 2012:chap ...

215

Mitral Valve Prolapse  

MedlinePLUS

... from flowing back into the atria. For more information, go to the Health Topics How the Heart Works article. This article contains animations that show how your heart pumps blood and how your heart's electrical system works. Mitral Valve Prolapse In MVP, when the ...

216

Model Heart Valves  

NSDL National Science Digital Library

Students use provided materials to design and build prototype artificial heart valves. Their functioning is demonstrated using water to simulate the flow of blood through the heart. Upon completion, teams demonstrate their fully functional prototypes to the rest of the class, along with a pamphlet that describes the device and how it works.

Vu Bioengineering Ret Program

217

Transcatheter aortic valve-in-valve implantation of a CoreValve in a degenerated stenotic Sapien heart valve prosthesis.  

PubMed

Treatment options for re-stenotic aortic valve prosthesis implanted by transcatheter technique have not been evaluated systematically. We describe the case of a 75-year-old dialysis patient who was treated by transcatheter aortic valve implantation 3.5 years ago and now presented with severe stenosis of the percutaneous heart valve. The patient was initially treated with a trans-apical implantation of an Edwards Sapien 26 mm balloon expandable valve. The patient remained asymptomatic for 3 years when he presented with increasing shortness of breath and significant calcification of the valve prosthesis on transesophageal echocardiography. Valve-in-valve percutaneous heart valve implantation using a 26-mm CoreValve prosthesis was performed under local anesthesia. The prosthesis was implanted without prior valvuloplasty. Pacing with a frequency of 140/min was applied during placement of the valve prosthesis. Positioning was done with great care using only fluoroscopic guidance with the aim to have the ventricular strut end of the CoreValve prosthesis 5 mm higher than the ventricular strut end of the Edwards Sapien prosthesis. After placement of the CoreValve prosthesis within the Edwards Sapien valve additional valvuloplasty with rapid pacing was performed in order to further expand the CoreValve prosthesis. The final result was associated with a remaining mean gradient of 5 mm Hg and no aortic regurgitation. In conclusion, implantation of a CoreValve prosthesis for treatment of a restenotic Edwards Sapien prosthesis is feasible and is associated with a good functional result. PMID:22707435

Hoffmann, Rainer; Mllmann, Helge; Lotfi, Shahram

2013-12-01

218

Leishmaniasis Direct Agglutination Test: Using Pictorials as Training Materials to Reduce Inter-Reader Variability and Improve Accuracy  

PubMed Central

Background The Direct Agglutination Test (DAT) has a high diagnostic accuracy and remains, in some geographical areas, part of the diagnostic algorithm for Visceral Leishmaniasis (VL). However, subjective interpretation of results introduces potential for inter-reader variation. We report an assessment of inter-laboratory agreement and propose a pictorial-based approach to standardize reading of the DAT. Methodology In preparation for a comparative evaluation of immunochromatographic diagnostics for VL, a proficiency panel of 15 well-characterized sera, DAT-antigen from a single batch and common protocol was sent to nine laboratories in Latin-America, East-Africa and Asia. Agreement (i.e., equal titre or within 1 titer) with the reading by the reference laboratory was computed. Due to significant inter-laboratory disagreement on-site refresher training was provided to all technicians performing DAT. Photos of training plates were made, and end-titres agreed upon by experienced users of DAT within the Visceral-Leishmaniasis Laboratory-Network (VL-LN). Results Pre-training, concordance in DAT results with reference laboratories was only 50%, although agreement on negative sera was high (94%). After refresher training concordance increased to 84%; agreement on negative controls increased to 98%. Variance in readings significantly decreased after training from 3.3 titres to an average of 1.0 titre (two-sample Wilcoxon rank-sum (Mann-Whitney) test (z?=??3,624 and p?=?0.0003)). Conclusion The most probable explanation for disagreement was subjective endpoint reading. Using pictorials as training materials may be a useful tool to reduce disparity in results and promote more standardized reading of DAT, without compromising diagnostic sensitivity. PMID:23272257

Adams, Emily R.; Jacquet, Diane; Schoone, Gerard; Gidwani, Kamlesh; Boelaert, Marleen; Cunningham, Jane

2012-01-01

219

Multi-port valve assembly  

DOEpatents

A multi-port fluid valve apparatus is used to control the flow of fluids through a plurality of valves and includes a web, which preferably is a stainless steel endless belt. The belt has an aperture therethrough and is progressed, under motor drive and control, so that its aperture is moved from one valve mechanism to another. Each of the valve mechanisms comprises a pair of valve blocks which are held in fluid-tight relationship against the belt. Each valve block consists of a block having a bore through which the fluid flows, a first seal surrounding the bore and a second seal surrounding the first seal, with the distance between the first and second seals being greater than the size of the belt aperture. In order to open a valve, the motor progresses the belt aperture to where it is aligned with the two bores of a pair of valve blocks, such alignment permitting a flow of the fluid through the valve. The valve is closed by movement of the belt aperture and its replacement, within the pair of valve blocks, by a solid portion of the belt.

Guggenheim, S. Frederic (Teaneck, NJ)

1986-01-01

220

Vibrations due to a test train at variable speeds in a deep bored tunnel embedded in London clay  

Microsoft Academic Search

This paper reports on the results of in situ vibration measur ements that have been performed within the frame of the CONVURT project at a site in Regent's Park on t he Bakerloo line of London Under- ground during 35 passages of a test train at a speed between 20 and 50 km\\/h. Vibration measurements have been performed on the

G. Degrande; P. Chatterjee; R. Klein; W. Van de Velde

221

Classroom Management Training, Teaching Experience and Gender: Do These Variables Impact Teachers' Attitudes and Beliefs toward Classroom Management Style?  

ERIC Educational Resources Information Center

This study represents a continuation of research efforts to further refine the Attitudes and Beliefs on Classroom Control (ABCC) Inventory. The purposes of this study were to investigate the: (1) impact of classroom management training on classroom management style; (2) differences in attitudes toward classroom management between novice and

Martin, Nancy K.; Yin, Zenong; Mayall, Hayley

2006-01-01

222

Variables Influencing the Return on Investment in Management Training Programs: A Utility Analysis of 10 Swiss Cases  

ERIC Educational Resources Information Center

In this article, we present the utility analysis approach as an alternative and promising approach to measure the return on investment in managerial training programs. This approach, linking economic value with competencies developed by trainees, enables researchers and decision-makers to compare the return on investment from different programs in

Chochard, Yves; Davoine, Eric

2011-01-01

223

Self Contained Temperature Actuated Control Valves  

E-print Network

control valves and surface temperature control valves (to provide setqp and freeze protection), fluid sensing control valves, air fluid sensing control valves, safety shower val~es (to provide both freeze and scald protection) and condensate freeze... product, discoloration and steam waste. Use of TL valves, ST valves and CTV (condensate temperature valves) can virtually eliminate these associated problems. Table I shows the percentage of steam saved on higher temperature freeze products. Three...

Pirkle, F.

1979-01-01

224

Diversity training for signal transduction: leveraging cell-to-cell variability to dissect cellular signaling, differentiation and death  

PubMed Central

Populations of identical cells are rarely truly identical. Even when in the same state of differentiation, isogenic cells may vary in expression of key signaling regulators, activate signal transduction at different thresholds, and consequently respond heterogeneously to a given stimulus. Here, we review how new experimental and analytical techniques are suited to connect these different levels of variability, quantitatively mapping the effects of cell-to-cell variability on cellular decision-making. In particular, we summarize how this helps classify signaling regulators according to the impact of their variability on biological functions. We further discuss how variability can also be leveraged to shed light on the molecular mechanisms regulating cellular signaling, from the individual cell to the population of cells as a whole. PMID:23747193

Cotari, Jesse W.; Voisinne, Guillaume; Altan-Bonnet, Gregoire

2013-01-01

225

Diversity training for signal transduction: leveraging cell-to-cell variability to dissect cellular signaling, differentiation and death.  

PubMed

Populations of 'identical' cells are rarely truly identical. Even when in the same state of differentiation, isogenic cells may vary in expression of key signaling regulators, activate signal transduction at different thresholds, and consequently respond heterogeneously to a given stimulus. Here, we review how new experimental and analytical techniques are suited to connect these different levels of variability, quantitatively mapping the effects of cell-to-cell variability on cellular decision-making. In particular, we summarize how this helps classify signaling regulators according to the impact of their variability on biological functions. We further discuss how variability can also be leveraged to shed light on the molecular mechanisms regulating cellular signaling, from the individual cell to the population of cells as a whole. PMID:23747193

Cotari, Jesse W; Voisinne, Guillaume; Altan-Bonnet, Grgoire

2013-08-01

226

Transvenous Transcatheter Valve-in-Valve Implantation after Bioprosthetic Tricuspid Valve Failure  

PubMed Central

We describe the case of a 38-year-old man with a history of metastatic testicular cancer who had undergone multiple thoracic surgical procedures, including tricuspid valve replacement with a bioprosthetic valve as a result of tricuspid involvement of his malignancy. He presented at our outpatient cardiology clinic with worsening fatigue, shortness of breath, and peripheral edema, investigation of which revealed severe tricuspid bioprosthesis stenosis with central regurgitation. Because of the patient's medical history, he was considered to be a high-risk surgical candidate. Therefore, transcatheter tricuspid valve-in-valve implantation of a 26-mm Edwards Sapien valve was attempted through a transjugular approach. The procedure restored tricuspid valvar competence and substantially improved the patient's symptoms. We discuss the technical aspects of this case and briefly review the usefulness of the valve-in-valve technique in the tricuspid position. PMID:25425983

Reul, Ross M.; Cannizzaro, Leon; Dougherty, Kathryn G.

2014-01-01

227

Rotary multiposition valve  

SciTech Connect

The disclosure is directed to a rotary multiposition valve for selectively directing the flow of a fluid through a plurality of paths. The valve comprises an inner member and a hollow housing with a row of ducts on its outer surface. The ducts are in fluid communication with the housing. An engaging section of the inner member is received in the housing. A seal divides the engaging section into a hollow inlet segment and a hollow outlet segment. A plurality of inlet apertures are disposed in the inlet segment and a plurality of outlet apertures are disposed in the outlet segment. The inlet apertures are disposed in a longitudinally and radially spaced-apart pattern that can be a helix. The outlet apertures are disposed in a corresponding pattern. As the inner member is rotated, whenever an inlet aperture overlaps one of the ducts, the corresponding outlet aperture overlaps a different duct, thus forming a fluid pathway.

Barclay, John A. (Los Alamos, NM); Dyson, Jack E. (Los Alamos, NM)

1985-01-01

228

Rotary multiposition valve  

SciTech Connect

The disclosure is directed to a rotary multiposition valve for selectively directing the flow of a fluid through a plurality of paths. The valve comprises an inner member and a hollow housing with a row of ducts on its outer surface. The ducts are in fluid communication with the housing. An engaging section of the inner member is received in the housing. A seal divides the engaging section into a hollow inlet segment and a hollow outlet segment. A plurality of inlet apertures are disposed in the inlet sgegment and a plurality of outlet apertures are disposed in the outlet segment. The inlet apertures are disposed in a longitudinally and radially spaced-apart pattern that can be a helix. The outlet apertures are disposed in a corresponding pattern. As the inner member is rotated, whenever an inlet aperture overlaps one of the ducts, the corresponding outlet aperture overlaps a different duct, thus forming a fluid pathway.

Barclay, J.A.; Dyson, J.E.

1984-04-06

229

Rotary multiposition valve  

SciTech Connect

The disclosure is directed to a rotary multiposition valve for selectively directing the flow of a fluid through a plurality of paths. The valve comprises an inner member and a hollow housing with a row of ducts on its outer surface. The ducts are in fluid communication with the housing. An engaging section of the inner member is received in the housing. A seal divides the engaging section into a hollow inlet segment and a hollow outlet segment. A plurality of inlet apertures are disposed in the inlet segment and a plurality of outlet apertures are disposed in the outlet segment. The inlet apertures are disposed in a longitudinally and radially spaced-apart pattern that can be a helix. The outlet apertures are disposed in a corresponding pattern. As the inner member is rotated, whenever an inlet aperture overlaps one of the ducts, the corresponding outlet aperture overlaps a different duct, thus forming a fluid pathway.

Barclay, J. A.; Dyson, J. E.

1985-11-19

230

Gas flow control valve  

SciTech Connect

A compact gas flow control valve is described comprising a valve body having a first, rotor cavity-defining portion and a second cover portion covering the rotor cavity, at least one of the body portions including inlet means communicating with the rotor chamber for receiving gas under pressure for providing the gas to the rotor chamber, at least one of the body portions including outlet means for delivery of the gas by the flow control valve, a rotor within the rotor cavity, the rotor including a flat surface, a flow control plate carried by the rotor, the flow control plate covering and lying against the flat surface of the rotor, the rotor having ports opening through the rotor surface, the ports being of sufficiently large size as not to limit the flow of the gas therethrough. The flow control plate comprises a thin, flat metal disc provided with gas flow control orifices extending therethrough and spaced circumferentially around the disc and in registry with respective ones of the ports, the rotor being of substantially greater thickness than the disc, the gas flow control being of different sizes and passage means for providing communication between the outlet means and at least a selected one of the flow control plate origices, selector means for orienting the rotor to permit flow only through selected flow control plate orifices and a corresponding rotor port for delivery by the outlet means.

Phlipot, J.R.; Pinkston, S.R.; Nurre, H.

1988-02-09

231

Fast-acting valve and uses thereof  

DOEpatents

A very fast acting valve capable of producing a very well-defined plug of gas suitable for filling a theta pinch vacuum vessel is given. The valve requires no springs, instead being stopped mainly by a nonlinear force. Thus, the valve is not subject to bouncing; and the ratio of the size of the valve housing to the size of the valve stem is smaller than it would be if springs were needed to stop the valve stem. Furthermore, the valve can be used for thousands of valve firings with no apparent valve damage.

Meyer, J.A.

1980-05-16

232

Slow opening valve. [valve design for shuttle portable oxygen system  

NASA Technical Reports Server (NTRS)

A valve control is described having a valve body with an actuator stem and a rotating handle connected to the actuator stem by a differential drive mechanism which, during uniform movement of the handle in one direction, initially opens the valve at a relatively slow rate and, thereafter, complete the valve movement at a substantially faster rate. A series of stop rings are received about the body in frictional abutting relationship and serially rotated by the handle to uniformly resist handle movement independently of the extent of handle movement.

Drapeau, D. F. (inventor)

1984-01-01

233

Performance Characteristics of an Isothermal Freeze Valve  

SciTech Connect

This document discusses performance characteristics of an isothermal freeze valve. A freeze valve has been specified for draining the DWPF melter at the end of its lifetime. Two freeze valve designs have been evaluated on the Small Cylindrical Melter-2 (SCM-2). In order to size the DWPF freeze valve, the basic principles governing freeze valve behavior need to be identified and understood.

Hailey, A.E.

2001-08-22

234

Update of transcatheter valve treatment  

PubMed Central

Transcatheter valve implantation or repair has been a very promising approach for the treatment of valvular heart diseases since transcatheter aortic valve implantation (TAVI) was successfully performed in 2002. Great achievements have been made in this field (especially TAVI and transcatheter mitral valve repairMitraClip system) in recent years. Evidence from clinical trials or registry studies has proved that transcatheter valve treatment for valvular heart diseases is safe and effective in surgical high-risk or inoperable patients. As the evidence accumulates, transcatheter valve treatment might be an alterative surgery for younger patients with surgically low or intermediate risk valvular heart diseases in the near future. In this paper, the updates on transcatheter valve treatment are reviewed. PMID:23897785

Liu, Xian-bao; Wang, Jian-an

2013-01-01

235

Biofeedback training of nasal muscles using internal and external surface electromyography of the nose  

Microsoft Academic Search

BackgroundThe purpose of this paper is to describe the outcome of biofeedback training of nasal muscles in cases of nasal valve stenosis and collapse. The present study was performed to investigate the best way of using surface electromyography (sEMG) in biofeedback training of muscles involved in nasal valve function. In the present study, we present the way of biofeedback training

Michael Vaiman; Nathan Shlamkovich; Alex Kessler; Ephraim Eviatar; Samuel Segal

2005-01-01

236

Semi-active compressor valve  

DOEpatents

A method and system for fine-tuning the motion of suction or discharge valves associated with cylinders of a reciprocating gas compressor, such as the large compressors used for natural gas transmission. The valve's primary driving force is conventional, but the valve also uses an electromagnetic coil to sense position of the plate (or other plugging element) and to provide an opposing force prior to impact.

Brun, Klaus (Helotes, TX); Gernentz, Ryan S. (San Antonio, TX)

2010-07-27

237

Streamline coal slurry letdown valve  

DOEpatents

A streamlined coal slurry letdown valve is featured which has a two-piece throat comprised of a seat and seat retainer. The two-piece design allows for easy assembly and disassembly of the valve. A novel cage holds the two-piece throat together during the high pressure letdown. The coal slurry letdown valve has long operating life as a result of its streamlined and erosion-resistance surfaces. 5 figs.

Platt, R.J.; Shadbolt, E.A.

1983-11-08

238

Sequenced drive for rotary valves  

DOEpatents

A sequenced drive for rotary valves which provides the benefits of applying rotary and linear motions to the movable sealing element of the valve. The sequenced drive provides a close approximation of linear motion while engaging or disengaging the movable element with the seat minimizing wear and damage due to scrubbing action. The rotary motion of the drive swings the movable element out of the flowpath thus eliminating obstruction to flow through the valve.

Mittell, Larry C. (Palos Verdes Estates, CA)

1981-01-01

239

Chrysophyte cyst-inferred variability of warm season lake water chemistry and climate in northern Poland: training set and downcore reconstruction  

NASA Astrophysics Data System (ADS)

Transfer Functions based on modern training sets are well established and powerful tools in quantitative paleolimnology and environmental/climate reconstructions. Lake sediments are excellent natural archive to reconstruct long-term climate and environmental fluctuations. In this sense, the project 'Climate of northern Poland during the last 1000 years: Constraining the future with the past' (CLIMPOL) aims to develop quantitative climate reconstruction in northern Poland during the last millennium using lake sediments. The Polish training set consists of Chrysophyte cyst (golden brown algae, class Chrysophyceae) sediment trap and surface sediment samples, and data for 19 environmental variables collected from 50 lakes in northern Poland. Canonical correspondence analyses (CCA) revealed that water electric conductivity, total nitrogen, total phosphorous, turbidity, cation and anion compositions (Ca2+, HCO3-) contributed significantly to explaining chrysophytes distribution in the lakes of the training set. A quantitative transfer function was then developed to estimate Ca2+ (log10 transformed) from modern chrysophyte cysts assemblages using weighted-averaging regression (WA) with classical deshrinking. The bootstrapped regression coefficient (R2boot) was 0.68, with a root-mean square error of prediction (RMSEP) of 0.143 (log10 units). The calibration model was applied to a varved sedimentary sequence (AD 1898-2010) from Lake ?abi?skie, Masurian Lakeland (NE Poland). Cyst-inferred lake water Ca2+ concentrations were significantly correlated with zonal wind speed (ms-1) (R=0.50; padj<0.001; AD 1898-2010; 3-yr filtered). We suggest that these changes in calcite precipitation in Lake ?abi?skie depend on the lake mixing regime, driven by westerly winds. Observational data from this lake show that the Ca2+ variability in the epilimnion depends on the efficiency of Ca2+ scavenging by CaCO3 precipitation in early summer which, in turn, is a function of water column stratification, temperature and the wind regime from late spring to early fall. This study demonstrates that chrysophyte cysts assemblages in Polish lakes respond to hydrochemical factors driven by climate variability.

Hernndez-Almeida, Ivn; Grosjean, Martin; Tylmann, Wojciech; Bonk, Alicja

2014-05-01

240

Internal Acoustics of a Pintle Valve with Supercritical Helium Flow  

NASA Technical Reports Server (NTRS)

Large amplitude flow unsteadiness is a common phenomenon within the high flow rate ducts and valves associated with propulsion systems. Boundary layer noise, shear layers and vortex shedding are a few of the many sources of flow oscillations. The presence of lightly damped acoustic modes can organize and amplify these sources of flow perturbation, causing undesirable loading of internal parts. The present study investigates the self-induced acoustic environment within a pintle valve subject to high Reynolds Number flow of helium gas. Experiments were conducted to measure the internal pressure oscillations of the Ares I Launch Abort System (LAS) Attitude Control Motor (ACM) valve. The AGM consists of a solid propellant gas generator with eight pintle valves attached to the aft end. The pintle valve is designed to deliver variable upstream conditions to an attache( converging diverging nozzle. In order to investigate the full range of operating conditions 28 separate tests were conducted with varying pintle position and upstream pressure. Helium gas was utilized in order to closely mimic the speed of sound of the gas generator exhaust, minimizing required scaling during data analysis. The recordec pressure measurements were interrogated to multiple ends. The development of root mean square (RMS) value! versus Reynolds Number and Pintle position are important to creating bounding unsteady load curves for valve internal parts. Spectral analysis was also performed, helping to identify power spectral densities (PSD) of acoustic natural frequencies and boundary layer noise. An interesting and unexpected result was the identification of an acoustic mode within the valve which does not respond until the valve was over 60% open. Further, the response amplitude around this mode can be as large or larger than those associated with lower frequency modes.

Fishbach, Sean R.; Davis, R. Benjamin

2010-01-01

241

Valve-"Health"-Monitoring System  

NASA Technical Reports Server (NTRS)

A system that includes sensors and data acquisition, wireless data-communication, and data-processing subsystems has been developed as a means of both real-time and historical tracking of information indicative of deterioration in the mechanical integrity and performance of a highgeared ball valve or a linearly actuated valve that operates at a temperature between cryogenic and ambient.

Jensen, Scott L.; Drouant, George J.

2009-01-01

242

Valve designed with elastic seat  

NASA Technical Reports Server (NTRS)

Absolute valve closure is accomplished by a machined valve with an axially annular channel which changes the outlet passage into a thin tubular elastic seat member with a retainer backup ring. The elasticity of the seat provides tight conformity to ball irregularity.

Mac Glashan, W. F., Jr.

1965-01-01

243

Surface treatment for valve seats  

NASA Technical Reports Server (NTRS)

Valve with embedded fine particles of diamond in the metal surface of the valve seat resists galling, corrosion, erosion, and cold welding. Diamond powder has an average particle diameter of 0.01 micron and is used with a standard fine diamond polishing compound.

Macglashan, W. F., Jr.

1970-01-01

244

Mitral Valve Annuloplasty  

PubMed Central

Mitral valve annuloplasty is a common surgical technique used in the repair of a leaking valve by implanting an annuloplasty device. To enhance repair durability, these devices are designed to increase leaflet coaptation, while preserving the native annular shape and motion; however, the precise impact of device implantation on annular deformation, strain, and curvature is unknown. Here we quantify how three frequently used devices significantly impair native annular dynamics. In controlled in vivo experiments, we surgically implanted eleven flexible-incomplete, eleven semi-rigid-complete, and twelve rigid-complete devices around the mitral annuli of 34 sheep, each tagged with 16 equally-spaced tantalum markers. We recorded four-dimensional marker coordinates using biplane videofluoroscopy, first with device and then without, which were used to create mathematical models using piecewise cubic splines. Clinical metrics (characteristic anatomical distances) revealed significant global reduction in annular dynamics upon device implantation. Mechanical metrics (strain and curvature fields) explained this reduction via a local loss of anterior dilation and posterior contraction. Overall, all three devices unfavorably reduced annular dynamics. The flexible-incomplete device, however, preserved native annular dynamics to a larger extent than the complete devices. Heterogeneous strain and curvature profiles suggest the need for heterogeneous support, which may spawn more rational design of annuloplasty devices using design concepts of functionally graded materials. PMID:22037916

Rausch, Manuel K.; Bothe, Wolfgang; Kvitting, John-Peder Escobar; Swanson, Julia C.; Miller, D. Craig; Kuhl, Ellen

2012-01-01

245

The effects of autogenic-feedback training on motion sickness severity and heart rate variability in astronauts  

NASA Technical Reports Server (NTRS)

Space motion sickness (SMS) affects 50 percent of all people during early days of spaceflight. This study describes the results of two Shuttle flight experiments in which autogenic-feedback training (AFT), a physiological conditioning method, was tested as a treatment for this disorder. Of the six who were designated as flight subjects (two women and four men), three were given treatment and three served as controls (i.e., no AFT). Treatment subjects were given 6 hours of preflight AFT. Preflight results showed that AFT produced a significant increase in tolerance to rotating chair motion sickness tests. Further, this increased tolerance was associated with changes in specific physiological responses and reports of reduced malaise. Flight results showed that two of the three control subjects experienced repeated vomiting on the first mission day, while one subject experienced only moderate malaise. Of the three treatment subjects, one experienced mild discomfort, one moderate discomfort, and one severe motion sickness. Only the three control subjects took medication for symptom suppression. Measures of cardiac function reflective of vagal control were shown to be affected especially strongly on the first day of space flight. AFT given for control of heart rate, respiration, and other autonomic activity influenced both the vagal control measures and SMS. These data suggest that AFT may be an effective treatment for space motion sickness; however, this cannot be demonstrated conclusively with the small number of subjects described.

Toscano, William B.; Cowings, Patricia S.

1994-01-01

246

Gasoline-like Fuel Effects on High-load, Boosted HCCI Combustion Employing Negative Valve Overlap Strategy  

SciTech Connect

In recent years a number of studies have demonstrated that boosted operation combined with external EGR is a path forward for expanding the high load limit of homogeneous charge compression ignition (HCCI) operation with the negative valve overlap (NVO) valve strategy. However, the effects of fuel composition with this strategy have not been fully explored. In this study boosted HCCI combustion is investigated in a single-cylinder research engine equipped with direct injection (DI) fueling, cooled external exhaust gas recirculation (EGR), laboratory pressurized intake air, and a fully-variable hydraulic valve actuation (HVA) valve train. Three fuels with significant compositional differences are investigated: regular grade gasoline (RON = 90.2), 30% ethanol-gasoline blend (E30, RON = 100.3), and 24% iso-butanol-gasoline blend (IB24, RON = 96.6). Results include engine loads from 350 to 800 kPa IMEPg for all fuels at three engine speeds 1600, 2000, and 2500 rpm. All operating conditions achieved thermal efficiency (gross indicated efficiency) between 38 and 47%, low NOX emissions ( 0.1 g/kWh), and high combustion efficiency ( 96.5%). Detailed sweeps of intake manifold pressure (atmospheric to 250 kPaa), EGR (0 25% EGR), and injection timing are conducted to identify fuel-specific effects. The major finding of this study is that while significant fuel compositional differences exist, in boosted HCCI operation only minor changes in operational conditions are required to achieve comparable operation for all fuels. In boosted HCCI operation all fuels were able to achieve matched load-speed operation, whereas in conventional SI operation the fuel-specific knock differences resulted in significant differences in the operable load-speed space. Although all fuels were operable in boosted HCCI, the respective air handling requirements are also discussed, including an analysis of the demanded turbocharger efficiency.

Kalaskar, Vickey B [ORNL] [ORNL; Szybist, James P [ORNL] [ORNL; Splitter, Derek A [ORNL] [ORNL

2014-01-01

247

Sex-specific responses to self-paced, high-intensity interval training with variable recovery periods.  

PubMed

This study examined sex-specific responses during self-paced, high-intensity interval training (HIIT). Sixteen (8 men and 8 women) individuals completed a peak oxygen uptake test and 3 treadmill HIIT sessions on separate days. The HIIT sessions consisted of six 4-minute intervals performed at the highest self-selected intensity individuals felt they could maintain. Recovery between intervals was counterbalanced and consisted of 1-, 2-, or 4-minute recovery during each trial. Relative measures of intensity, including percentage of velocity at VO2peak (vVO2peak), %VO2peak, %HRmax, and blood lactate concentration ([La]), were observed during the trials. Perceived readiness was recorded immediately before and ratings of perceived exertion (RPE) were recorded at the end of each interval with session RPE recorded after each trial. Results revealed a significant effect of sex on %vVO2peak (p < 0.01) and %HRmax (p < 0.01). Data show that across trials, men self-select higher %vVO2peak (84.5 vs. 80.7%), whereas women produce higher %HRmax (96.9 vs. 92.1%) and %VO2peak (89.6 vs. 86.1%) with no difference in [La] or perceptual responses. These findings support the notion that women may demonstrate improved recovery during high-intensity exercise, as they will self-select intensities resulting in greater cardiovascular strain. Moreover, results confirm previous findings suggesting that a 2:1 work-to-rest ratio is optimal during HIIT for both men and women. PMID:23838976

Laurent, C Matthew; Vervaecke, Lauren S; Kutz, Matthew R; Green, J Matthew

2014-04-01

248

Long-term exercise training with constant energy intake. 1: Effect on body composition and selected metabolic variables.  

PubMed

The effects of long-term negative energy balance generated by exercise while maintaining a constant energy intake were studied in five healthy young males (25 +/- 3 years; mean +/- s.d.). After 2 weeks of monitoring to determine habitual energy intake, they were subjected to a 100-day experimental period during which they exercised on a cycle ergometer, 6 days a week, twice a day at 55 per cent of VO2 max. The daily energy deficit was 4.2 MJ for a total of 353 MJ for the duration of the treatment. Body weight decreased from 86.7 to 78.7 kg (P less than 0.001). More than 80 per cent of the weight loss was accounted for by the reductions in fat mass. Fat-free mass did not change significantly. The data suggest that subcutaneous fat was lost about evenly from the trunk and from the limbs as estimated from skinfolds. Cardiorespiratory and metabolic responses to submaximal work loads indicate that the low intensity exercise regimen was capable of inducing some of the known adaptations of exercise training such as a decrease in plasma insulin and norepinephrine concentrations during exercise, reductions in heart rate, pulmonary ventilation and blood lactate concentration at a given exercise intensity, and an increase in skeletal muscle oxidative capacity. The energy cost of sitting and standing was not decreased in spite of the loss in body mass. However, the energy cost of submaximal cycling and walking exercises was reduced considerably. These results clearly demonstrate that it is quite possible to lose fat while preserving fat-free mass through regular prolonged exercise of moderate intensity if energy intake is kept constant at baseline level. They also emphasize the importance of the individual differences in response to negative energy balance. PMID:2179147

Bouchard, C; Tremblay, A; Nadeau, A; Dussault, J; Desprs, J P; Theriault, G; Lupien, P J; Serresse, O; Boulay, M R; Fournier, G

1990-01-01

249

Self-Rupturing Hermetic Valve  

NASA Technical Reports Server (NTRS)

For commercial, military, and aerospace applications, low-cost, small, reliable, and lightweight gas and liquid hermetically sealed valves with post initiation on/off capability are highly desirable for pressurized systems. Applications include remote fire suppression, single-use system-pressurization systems, spacecraft propellant systems, and in situ instruments. Current pyrotechnic- activated rupture disk hermetic valves were designed for physically larger systems and are heavy and integrate poorly with portable equipment, aircraft, and small spacecraft and instrument systems. Additionally, current pyrotechnically activated systems impart high g-force shock loads to surrounding components and structures, which increase the risk of damage and can require additional mitigation. The disclosed mechanism addresses the need for producing a hermetically sealed micro-isolation valve for low and high pressure for commercial, aerospace, and spacecraft applications. High-precision electrical discharge machining (EDM) parts allow for the machining of mated parts with gaps less than a thousandth of an inch. These high-precision parts are used to support against pressure and extrusion, a thin hermetically welded diaphragm. This diaphragm ruptures from a pressure differential when the support is removed and/or when the plunger is forced against the diaphragm. With the addition of conventional seals to the plunger and a two-way actuator, a derivative of this design would allow nonhermetic use as an on/off or metering valve after the initial rupturing of the hermetic sealing disk. In addition, in a single-use hermetically sealed isolation valve, the valve can be activated without the use of potential leak-inducing valve body penetrations. One implementation of this technology is a high-pressure, high-flow-rate rupture valve that is self-rupturing, which is advantageous for high-pressure applications such as gas isolation valves. Once initiated, this technology is self-energizing and requires low force compared to current pyrotechnic-based burst disk hermetic valves. This is a novel design for producing a single-use, self-rupturing, hermetically sealed valve for isolation of pressurized gas and/or liquids. This design can also be applied for single-use disposable valves for chemical instruments. A welded foil diaphragm is fully supported by two mated surfaces that are machined to micron accuracies using EDM. To open the valve, one of the surfaces is moved relative to the other to (a) remove the support creating an unsupported diaphragm that ruptures due to over pressure, and/or (b) produce tension in the diaphragm and rupture it.

Tucker, Curtis E., Jr.; Sherrit, Stewart

2011-01-01

250

Cavitation guide for control valves  

SciTech Connect

This guide teaches the basic fundamentals of cavitation to provide the reader with an understanding of what causes cavitation, when it occurs, and the potential problems cavitation can cause to a valve and piping system. The document provides guidelines for understanding how to reduce the cavitation and/or select control valves for a cavitating system. The guide provides a method for predicting the cavitation intensity of control valves, and how the effect of cavitation on a system will vary with valve type, valve function, valve size, operating pressure, duration of operation and details of the piping installation. The guide defines six cavitation limits identifying cavitation intensities ranging from inception to the maximum intensity possible. The intensity of the cavitation at each limit Is described, including a brief discussion of how each level of cavitation influences the valve and system. Examples are included to demonstrate how to apply the method, including making both size and pressure scale effects corrections. Methods of controlling cavitation are discussed providing information on various techniques which can be used to design a new system or modify an existing one so it can operate at a desired level of cavitation.

Tullis, J.P. [Tullis Engineering Consultants, Logan, UT (United States)

1993-04-01

251

Variable Delay Multi-Pulse Train for Fast Chemical Exchange Saturation Transfer and Relayed-Nuclear Overhauser Enhancement MRI  

PubMed Central

Purpose Chemical exchange saturation transfer (CEST) imaging is a new MRI technology allowing the detection of low concentration endogenous cellular proteins and metabolites indirectly through their exchangeable protons. A new technique, variable delay multi-pulse CEST (VDMP-CEST), is proposed to eliminate the need for recording full Z-spectra and performing asymmetry analysis to obtain CEST contrast. Methods The VDMP-CEST scheme involves acquiring images with two (or more) delays between radiofrequency saturation pulses in pulsed CEST, producing a series of CEST images sensitive to the speed of saturation transfer. Subtracting two images or fitting a time series produces CEST and relayed-nuclear Overhauser enhancement CEST maps without effects of direct water saturation and, when using low radiofrequency power, minimal magnetization transfer contrast interference. Results When applied to several model systems (bovine serum albumin, crosslinked bovine serum albumin, l-glutamic acid) and in vivo on healthy rat brain, VDMP-CEST showed sensitivity to slow to intermediate range magnetization transfer processes (rate < 100150 Hz), such as amide proton transfer and relayed nuclear Overhauser enhancement-CEST. Images for these contrasts could be acquired in short scan times by using a single radiofrequency frequency. Conclusions VDMP-CEST provides an approach to detect CEST effect by sensitizing saturation experiments to slower exchange processes without interference of direct water saturation and without need to acquire Z-spectra and perform asymmetry analysis. PMID:23813483

Xu, Jiadi; Yadav, Nirbhay N.; Bar-Shir, Amnon; Jones, Craig K.; Chan, Kannie W. Y.; Zhang, Jiangyang; Walczak, P.; McMahon, Michael T.; van Zijl, Peter C. M.

2013-01-01

252

A reversible molecular valve  

PubMed Central

In everyday life, a macroscopic valve is a device with a movable control element that regulates the flow of gases or liquids by blocking and opening passageways. Construction of such a device on the nanoscale level requires (i) suitably proportioned movable control elements, (ii) a method for operating them on demand, and (iii) appropriately sized passageways. These three conditions can be fulfilled by attaching organic, mechanically interlocked, linear motor molecules that can be operated under chemical, electrical, or optical stimuli to stable inorganic porous frameworks (i.e., by self-assembling organic machinery on top of an inorganic chassis). In this article, we demonstrate a reversibly operating nanovalve that can be turned on and off by redox chemistry. It traps and releases molecules from a maze of nanoscopic passageways in silica by controlling the operation of redox-activated bistable [2]rotaxane molecules tethered to the openings of nanopores leading out of a nanoscale reservoir. PMID:16006520

Nguyen, Thoi D.; Tseng, Hsian-Rong; Celestre, Paul C.; Flood, Amar H.; Liu, Yi; Stoddart, J. Fraser; Zink, Jeffrey I.

2005-01-01

253

Stemless ball valve  

NASA Technical Reports Server (NTRS)

A stemless ball valve comprising: a right flange; left flange; ball with an axis pin and two travel pins; ball seal on either side of the ball; guide sleeve with inner walls comprising two channels; cartridge guide holder; inner magnetic cartridge; and outer magnetic cartridge. The ball is situated inside of the guide sleeve, and a travel pin is located in each of the two channels. The guide sleeve is situated inside of the cartridge guide holder, which is located adjacent to and outside of the inner magnetic cartridge and secured to the inner magnetic cartridge such that when the inner magnetic cartridge rotates, the cartridge guide holder also rotates. The cartridge guide holder is secured to the guide sleeve such that when the cartridge guide holder rotates, the travel pins move within the channels in the inner walls of the guide sleeve, thereby causing the ball to rotate.

Burgess, Kevin (Inventor); Yakos, David (Inventor); Walthall, Bryan (Inventor)

2012-01-01

254

Mechanical aortic valve-on-valve replacement in previous Bentall procedure: an alternate technique.  

PubMed

Acute aortic valve regurgitation due to thrombosed prosthetic valve can present as a surgical emergency. This article reports a successful and unusual management of a young pregnant female patient who presented with acute aortic valve regurgitation due to a thrombosed mechanical aortic valve. As the patient had previous multiple cardiac surgeries, the options were limited for repeat aortic valve or aortic root replacement. The patient had caesarean section followed by implantation of a mechanical valve-on-valve in a previously placed composite valved conduit. This technique may be useful for reoperative valve replacement in the setting of a prior mechanical Bentall patient. PMID:25193228

Manoly, Imthiaz; Krishnan, Monica; Hoschtitzky, J Andreas; Hasan, Ragheb

2014-09-01

255

Multi-port valve  

DOEpatents

A multi-port valve is described for regulating, as a function of ambient air having varying wind velocity and wind direction in an open-field control area, the distribution of a fluid, particularly carbon dioxide (CO{sub 2}) gas, in a fluid distribution system so that the control area remains generally at an elevated fluid concentration or level of said fluid. The multi-port valve generally includes a multi-port housing having a plurality of outlets there through disposed in a first pattern of outlets and at least one second pattern of outlets, and a movable plate having a plurality of apertures extending there through disposed in a first pattern of apertures and at least one second pattern of apertures. The first pattern of apertures being alignable with the first pattern of outlets and the at least one second pattern of apertures being alignable with the second pattern of outlets. The first pattern of apertures has a predetermined orientation with the at least one second pattern of apertures. For an open-field control area subject to ambient wind having a low velocity from any direction, the movable plate is positioned to equally distribute the supply of fluid in a fluid distribution system to the open-field control area. For an open-field control area subject to ambient wind having a high velocity from a given direction, the movable plate is positioned to generally distribute a supply of fluid in a fluid distribution system to that portion of the open-field control area located upwind. 7 figs.

Lewin, K.F.

1997-04-15

256

Multi-port valve  

DOEpatents

A multi-port valve for regulating, as a function of ambient air having varying wind velocity and wind direction in an open-field control area, the distribution of a fluid, particularly carbon dioxide (CO.sub.2) gas, in a fluid distribution system so that the control area remains generally at an elevated fluid concentration or level of said fluid. The multi-port valve generally includes a multi-port housing having a plurality of outlets therethrough disposed in a first pattern of outlets and at least one second pattern of outlets, and a movable plate having a plurality of apertures extending therethrough disposed in a first pattern of apertures and at least one second pattern of apertures. The first pattern of apertures being alignable with the first pattern of outlets and the at least one second pattern of apertures being alignable with the second pattern of outlets. The first pattern of apertures has a predetermined orientation with the at least one second pattern of apertures. For an open-field control area subject to ambient wind having a low velocity from any direction, the movable plate is positioned to equally distribute the supply of fluid in a fluid distribution system to the open-field control area. For an open-field control area subject to ambient wind having a high velocity from a given direction, the movable plate is positioned to generally distribute a supply of fluid in a fluid distribution system to that portion of the open-field control area located upwind.

Lewin, Keith F. (Calverton, NY)

1997-04-15

257

Outcome following isolated tricuspid valve replacement  

Microsoft Academic Search

Objectives: The clinical outcome of isolated tricuspid valve replacement is not well defined because this procedure is usually performed concomitantly with other valve surgery. Methods: We retrospectively studied the short and long-term outcome of 15 consecutive patients (six men and nine women, aged 613 years) undergoing isolated tricuspid valve replacement from 1984 to 1996. The cause of valve dysfunction was

Arduino A Mangoni; Thomas G DiSalvo; Gus J Vlahakes; Carisi A Polanczyk; Michael A Fifer

2001-01-01

258

Subsea valve apparatus having hydrate inhibiting injection  

Microsoft Academic Search

In accordance with an illustrative embodiment of the present invention, a valve placed in a subsea blowout preventer stack during a production test of a well producing gas comprises a valve body containing two valve elements in series and a releasable control unit. A fluid to inhibit the formation of natural-gas hydrates can be injected into the valve body by

J. Franc; P. H. Goldschild

1981-01-01

259

49 CFR 192.145 - Valves.  

Code of Federal Regulations, 2012 CFR

...192.145 Valves. (a) Except for cast iron and plastic valves, each valve...contained in those requirements. (b) Each cast iron and plastic valve must comply with...and/or end flange) components made of cast iron, malleable iron, or ductile...

2012-10-01

260

49 CFR 192.145 - Valves.  

Code of Federal Regulations, 2011 CFR

...192.145 Valves. (a) Except for cast iron and plastic valves, each valve...contained in those requirements. (b) Each cast iron and plastic valve must comply with...and/or end flange) components made of cast iron, malleable iron, or ductile...

2011-10-01

261

Heart Valve Lesson Plan Biomedical Engineering  

E-print Network

Heart Valve Lesson Plan Biomedical Engineering Objective · Introduce students to biomedical Learning Outcomes · Students will understand the role and function of heart valves. · Students will learn does a heart valve work? · Why do we need to replace heart valves? Time Required (Itemized) · Lecture

Provancher, William

262

Saving a Life: Heart Valve Replacement  

NSDL National Science Digital Library

Students use their knowledge about how healthy heart valves function to design, construct and implant prototype replacement mitral valves for hypothetical patients' hearts. Building on what they learned in the associated lesson about artificial heart valves, combined with the testing and scoring of their prototype heart valve designs in this activity, students discover the pros and cons of different types of artificial heart valves based on materials, surgery requirements, and lifespan.

Integrated Teaching And Learning Program

263

EGR valve device of internal combustion engines of automobiles  

Microsoft Academic Search

An EGR valve device is described for internal combustion engines of automobiles, consisting of: a valve body; a valve rod slidably borne on the valve body and having, at one end, a valve member capable of opening and closing an exhaust gas recirculation path and being urged to close the valve; a sector-shaped member rotatably supported on the valve body

H. Makino; A. Sasaki

1987-01-01

264

Bipropellant shut-off valve  

NASA Technical Reports Server (NTRS)

An advanced design of an all metal, fast response, bipropellant, shut-off valve for use on long duration space missions is reported. The valve provides the flow control capability for a 1,000 lb thrust, bipropellant engine using oxygen difluoride and diborane as propellants. The shutoff seal selection is a soft-on-hard metal concept. The soft seal is a spherical shell that seats against a hard conical seat. Beryllium copper and beryllium nickel seals were selected to seal against an electrolyzed Inconel 718 seat. Poppet shaft sealing is achieved by use of hydroformed, Inconel 718 bellows. Two valve assemblies were fabricated and subjected to a series of tests including leak, response time, flow capacity, dry cycles, water cycles, liquid nitrogen cycles, liquid fluorine cycles, and lead-lag operation cycles. These tests demonstrated the ability of the valve to meet design goals.

Smith, J. V.

1971-01-01

265

Mitral valve surgery - minimally invasive  

MedlinePLUS

... rate will be slowed by medicine or a mechanical device. If your surgeon can repair your mitral ... There are two main types of new valves: Mechanical -- made of man-made materials, such as titanium ...

266

Liquid-blocking check valve  

DOEpatents

A liquid blocking check valve useful particularly in a pneumatic system utilizing a pressurized liquid fill chamber. The valve includes a floatable ball disposed within a housing defining a chamber. The housing is provided with an inlet aperture disposed in the top of said chamber, and an outlet aperture disposed in the bottom of said chamber in an offset relation to said inlet aperture and in communication with a cutaway side wall section of said housing.

Merrill, J.T.

1982-09-27

267

TRAINING IN INDUSTRY.  

ERIC Educational Resources Information Center

THIS CHAPTER IN A LARGER WORK ON INDUSTRIAL PSYCHOLOGY DEALS LARGELY WITH THE NEED TO SPECIFY TRAINING OBJECTIVES THROUGH JOB ANALYSIS, USES OF TESTING IN TRAINEE SELECTION, TRAINING VARIABLES AND LEARNING PROCESSES, TRAINING TECHNOLOGY (MAINLY THE CHARACTERISTICS OF PROGRAMED INSTRUCTION), THE EVALUATION OF PROFICIENCY, THE VALUE OF

GLASER, ROBERT

268

Annular flow diverter valve  

DOEpatents

A valve for diverting flow from the center of two concentric tubes to the annulus between the tubes or, operating in the reverse direction, for mixing fluids from concentric tubes into a common tube and for controlling the volume ratio of said flow consists of a toroidal baffle disposed in sliding engagement with the interior of the inner tube downstream of a plurality of ports in the inner tube, a plurality of gates in sliding engagement with the interior of the inner tube attached to the baffle for movement therewith, a servomotor having a bullet-shaped plug on the downstream end thereof, and drive rods connecting the servomotor to the toroidal baffle, the servomotor thereby being adapted to move the baffle into mating engagement with the bullet-shaped plug and simultaneously move the gates away from the ports in the inner tube and to move the baffle away from the bullet-shaped plug and simultaneously move the gates to cover the ports in the inner tube.

Rider, Robert L. (Walkersville, MD)

1980-01-01

269

Noninvasive valve monitor using alternating electromagnetic field  

DOEpatents

One or more electrical coils are carefully located on the outside of a valve body. An alternating current passing through the coil(s) results in an alternating electromagnetic field being transmitted into the valve body and valve internals. The electromagnetic field varies in intensity and polarity in the valve. As the position of a valve internal part is changed, the electromagnetic field throughout the valve body and its internals is altered. A passive receiver coil carefully located on the outside of the valve body detects the intensity of the electromagnetic field at that location as an induced electrical voltage in the coil. With the change in position of the valve internal part, there is a corresponding change in the induced voltage as a result of the alteration in the alternating electromagnetic field at that location. Changes in the voltage provide an indication of the position and motion of valve internals.

Eissenberg, D.M.; Haynes, H.D.; Casada, D.A.

1993-03-16

270

Noninvasive valve monitor using alternating electromagnetic field  

DOEpatents

One or more electrical coils are carefully located on the outside of a valve body. An alternating current passing through the coil(s) results in an alternating electromagnetic field being transmitted into the valve body and valve internals. The electromagnetic field varies in intensity and polarity in the valve. As the position of a valve internal part is changed, the electromagnetic field throughout the valve body and its internals is altered. A passive receiver coil carefully located on the outside of the valve body detects the intensity of the electromagnetic field at that location as an induced electrical voltage in the coil. With the change in position of the valve internal part, there is a corresponding change in the induced voltage as a result of the alteration in the alternating electromagnetic field at that location. Changes in the voltage provide an indication of the position and motion of valve internals.

Eissenberg, David M. (Oak Ridge, TN); Haynes, Howard D. (Knoxville, TN); Casada, Donald A. (Knoxville, TN)

1993-01-01

271

The elusive link between aortic wall histology and echocardiographic anatomy in bicuspid aortic valve: implications for prophylactic surgery  

Microsoft Academic Search

Objective: Prediction of aortic dissection or rupture is extremely difficult in patients with bicuspid aortic valve. We aimed to identify clinical and echocardiographic predictors of histological abnormalities of the aortic wall in patients with bicuspid aortic valve undergoing aortic surgery. Methods: We assessed the histology of the aortic wall and clinical and echocardiographic variables in a cohort of patients with

Ornella Leone; Elena Biagini; Davide Pacini; Silvia Zagnoni; Marinella Ferlito; Maddalena Graziosi; Roberto Di Bartolomeo; Claudio Rapezzi

272

Cross-sectional survey on minimally invasive mitral valve surgery  

PubMed Central

Background Minimally invasive mitral valve surgery (MIMVS) has become a standard technique to perform mitral valve surgery in many cardiac centers. However, there remains a question regarding when MIMVS should not be performed due to an increased surgical risk. Consequently, expert surgeons were surveyed regarding their opinions on patient factors, mitral valve pathology and surgical skills in MIMVS. Methods Surgeons experienced in MIMVS were identified through an electronic search of the literature. A link to an online survey platform was sent to all surgeons, as well as two follow-up reminders. Survey responses were then submitted to a central database and analyzed. Results The survey was completed by 20 surgeons. Overall results were not uniform with regard to contraindications to performing MIMVS. Some respondents do not consider left atrial enlargement (95% of surgeons), complexity of surgery (75%), age (70%), aortic calcification (70%), EuroSCORE (60%), left ventricular ejection fraction (55%), or obesity (50%) to be contraindication to surgery. Ninety percent of respondents believe more than 20 cases are required to gain familiarity with the procedure, while 85% believe at least one MIMVS case needs to be performed per week to maintain proficiency. Eighty percent recommend establishment of multi-institutional databases and standardized surgical mentoring courses, while 75% believe MIMVS should be incorporated into current training programs for trainees. Conclusions These results suggest that MIMVS has been accepted as a treatment option for patients with mitral valve pathologies according the expert panel. Initial training and continuing practice is recommended to maintain proficiency, as well as further research and formalization of training programs. PMID:24349974

Borger, Michael; Byrne, John G.; Chitwood, W. Randolph; Cohn, Lawrence; Galloway, Aubrey; Garbade, Jens; Glauber, Mattia; Greco, Ernesto; Hargrove, Clark W.; Holzhey, David M.; Krakor, Ralf; Loulmet, Didier; Mishra, Yugal; Modi, Paul; Murphy, Douglas; Nifong, L. Wiley; Okamoto, Kazuma; Seeburger, Joerg; Tian, David H.; Vollroth, Marcel; Yan, Tristan D.

2013-01-01

273

Surgical valve repair of isolated pulmonary valve endocarditis  

PubMed Central

Isolated pulmonary valve endocarditis (IPE) is an uncommon clinical entity. We reported 4 cases of IPE without underlying heart diseases that required surgical interventions. Two of the present patients had predisposing factors that included a history of abdominal surgery in Case 1 and intravenous drug abuse in Case 3. All four patients presented with persistent fever together with pulmonary symptoms despite appropriate antibiotic management. Three of the patients underwent elective pulmonary valve repair, but Case 3 underwent an urgent surgical intervention due to uncontrolled septic shock. Pulmonary valve repair was performed using autologous pericardial patch in all 4 patients. All of them had immediate postoperative recovery and satisfactory outcomes in the follow-up. PMID:23243038

Deng, Haibo; Ma, Yufen; Zhai, Haixin; Miao, Qi

2013-01-01

274

46 CFR 160.151-39 - Training of servicing technicians.  

Code of Federal Regulations, 2012 CFR

...certification of servicing technicians must include (1) Training and practice in packing an inflatable liferaft, repairing buoyancy tubes, repairing inflation-system valves, and other inspections and operations described in the approved servicing...

2012-10-01

275

46 CFR 160.151-39 - Training of servicing technicians.  

Code of Federal Regulations, 2011 CFR

...certification of servicing technicians must include (1) Training and practice in packing an inflatable liferaft, repairing buoyancy tubes, repairing inflation-system valves, and other inspections and operations described in the approved servicing...

2011-10-01

276

An electromechanical valve drive incorporating a nonlinear mechanical transformer  

E-print Network

In traditional internal combustion engines, a camshaft acts on the valve stems to open and close the valves. Valve timing is fixed relative to piston position. On the other hand, if a valve is flexibly controlled by a ...

Chang, Woo Sok, 1964-

2003-01-01

277

BORED AND ASSEMBLED GATE VALVES RECEIVING PROTECTIVE COATING IN THE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

BORED AND ASSEMBLED GATE VALVES RECEIVING PROTECTIVE COATING IN THE VALVE PAINT BOOTH OF THE VALVE ASSEMBLY BUILDING. - Stockham Pipe & Fittings Company, Valve Assembly Building, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

278

Light valve based on nonimaging optics with potential application in cold climate greenhouses  

NASA Astrophysics Data System (ADS)

We have evaluated a new concept for a variable light valve and thermal insulation system based on nonimaging optics. The system incorporates compound parabolic concentrators and can readily be switched between an open highly light transmissive state and a closed highly thermally insulating state. This variable light valve makes the transition between high thermal insulation and efficient light transmittance practical and may be useful in plant growth environments to provide both adequate sunlight illumination and thermal insulation as needed. We have measured light transmittance values exceeding 80% for the light valve design and achieved thermal insulation values substantially exceeding those of traditional energy efficient windows. The light valve system presented in this paper represents a potential solution for greenhouse food production in locations where greenhouses are not feasible economically due to high heating cost.

Valerio, Angel A.; Mossman, Michele A.; Whitehead, Lorne A.

2014-09-01

279

Failure and Life Cycle Evaluation of Watering Valves  

PubMed Central

Automated watering systems provide a reliable source of ad libitum water to animal cages. Our facility uses an automated water delivery system to support approximately 95% of the housed population (approximately 14,000 mouse cages). Drinking valve failure rates from 2002 through 2006 never exceeded the manufacturer standard of 0.1% total failure, based on monthly cage census and the number of floods. In 2007, we noted an increase in both flooding and cases of clinical dehydration in our mouse population. Using manufacturer's specifications for a water flow rate of 25 to 50 mL/min, we initiated a wide-scale screening of all valves used. During a 4-mo period, approximately 17,000 valves were assessed, of which 2200 failed according to scoring criteria (12.9% overall; 7.2% low flow; 1.6% no flow; 4.1% leaky). Factors leading to valve failures included residual metal shavings, silicone flash, introduced debris or bedding, and (most common) distortion of the autoclave-rated internal diaphragm and O-ring. Further evaluation revealed that despite normal autoclave conditions of heat, pressure, and steam, an extreme negative vacuum pull caused the valves internal silicone components (diaphragm and O-ring) to become distorted and water-permeable. Normal flow rate often returned after a drying out period, but components then reabsorbed water while on the animal rack or during subsequent autoclave cycles to revert to a variable flow condition. On the basis of our findings, we recalibrated autoclaves and initiated a preventative maintenance program to mitigate the risk of future valve failure. PMID:22330720

Gonzalez, David M; Graciano, Sandy J; Karlstad, John; Leblanc, Mathias; Clark, Tom; Holmes, Scott; Reuter, Jon D

2011-01-01

280

Propellant isolation shutoff valve program  

NASA Technical Reports Server (NTRS)

An analysis and design effort directed to advancing the state-of-the-art of space storable isolation valves for control of flow of the propellants liquid fluorine/hydrazine and Flox/monomethylhydrazine is discussed. Emphasis is on achieving zero liquid leakage and capability of withstanding missions up to 10 years in interplanetary space. Included is a study of all-metal poppet sealing theory, an evaluation of candidate seal configurations, a valve actuator trade-off study and design description of a pneumo-thermally actuated soft metal poppet seal valve. The concepts and analysis leading to the soft seal approach are documented. A theoretical evaluation of seal leakage versus seal loading, related finishes and yield strengths of various materials is provided. Application of a confined soft aluminum seal loaded to 2 to 3 times yield strength is recommended. Use of either an electro-mechanical or pneumatic actuator appears to be feasible for the application.

Merritt, F. L.

1973-01-01

281

Lost-motion valve actuator  

SciTech Connect

A lost-motion valve actuator is described for a bore closure valve employed in a well bore, comprising: operating connector means adapted to move the bore closure valve between open and closed positions through longitudinal movement of the operating connector means. The operating connector means comprises an operating connector and a connector insert defining a recess therebetween; locking dog means comprising at least one locking dog received in the recess and spring biasing means adapted to urge at least one locking dog radially inwardly; and mandrel means slidably received within the operating connector means and including dog slot means associated therewith. The dog slot means comprises an annular slot on the exterior of the mandrel means adapted to lockingly receive at least one inwardly biased locking dog when proximate thereto, whereby longitudinal movement of the mandrel means is transmitted to the operating connector means.

Burris, W.J. III; Ringgenberg, P.D.

1987-04-07

282

Prosthetic Mitral Valve Leaflet Escape  

PubMed Central

Leaflet escape of prosthetic valve is rare but potentially life threatening. It is essential to make timely diagnosis in order to avoid mortality. Transesophageal echocardiography and cinefluoroscopy is usually diagnostic and the location of the missing leaflet can be identified by computed tomography (CT). Emergent surgical correction is mandatory. We report a case of fractured escape of Edward-Duromedics mitral valve 27 years after the surgery. The patient presented with symptoms of acute decompensated heart failure and cardiogenic shock. She was instantly intubated and mechanically ventilated. After prompt evaluation including transthoracic echocardiography and CT, the escape of the leaflet was confirmed. The patient underwent emergent surgery for replacement of the damaged prosthetic valves immediately. Eleven days after the surgery, the dislodged leaflet in iliac artery was removed safely and the patient recovered well. PMID:23837121

Kim, Darae; Hun, Sin Sang; Cho, In-Jeong; Shim, Chi-Young; Ha, Jong-Won; Chung, Namsik; Ju, Hyun Chul; Sohn, Jang Won

2013-01-01

283

Non-collinear valve actuator  

NASA Technical Reports Server (NTRS)

A non-collinear valve actuator includes a primary actuating system and a return spring system with each applying forces to a linkage system in order to regulate the flow of a quarter-turn valve. The primary actuating system and return spring system are positioned non-collinearly, which simply means the primary actuating system and return spring system are not in line with each other. By positioning the primary actuating system and return spring system in this manner, the primary actuating system can undergo a larger stroke while the return spring system experiences significantly less displacement. This allows the length of the return spring to be reduced due to the minimization of displacement thereby reducing the weight of the return spring system. By allowing the primary actuating system to undergo longer strokes, the weight of the primary actuating system may also be reduced. Accordingly, the weight of the non-collinear valve actuator is reduced.

Richard, James A. (Inventor)

2012-01-01

284

Heart Valve Surgery Recovery and Follow Up  

MedlinePLUS

Heart Valve Surgery Recovery and Follow Up Updated:Sep 2,2014 What to expect after heart valve surgery The ... resources from Adam Pick's blog: Traveling Timeline After Heart Surgery 5 Things to Do While Your Heart Mends ( ...

285

Acoustic monitoring of power plant valves  

NASA Astrophysics Data System (ADS)

Advanced surveillance diagnostics were applied to key nuclear power plant valves to improve the availability of the power plant. Two types of valves were monitored: boiling water reactor (BWR) three-stage, pilot-operated safety/relief valves and pressurized water reactor (PWR) feedwater control valves. Excessive leakage across the pilot-disc seat in BWR safety/relief valves can cause the second-stage pressure to reach the critical value that activates the valve, even though the set pressure was not exceeded. Acoustic emission created by the leak noise were monitored and calibrated to indicate incipient activation of the safety/relief valve. Hydrodynamic, vibration, control and process signals frm PWR feedwater control valves were monitored by a mini-computer based surveillance system.

Allen, J. W.; Hartman, W. F.; Robinson, J. C.

1982-06-01

286

Casing shut-in valve system  

SciTech Connect

This patent describes a valve for use within a conduit in a subterranean well. It comprises a valve seat, a valve closure member adapted to rotate reversibly about a hinge point between open and closed positions through an included angle of less than 90 degrees, and means for selectively controlling movement of the valve closure member reversibly between the open and closed positions, the control means comprising means for biasing the valve closure member toward the closed position, the biasing means comprising spring strut assemblies rotatably connected to the valve closure member, with at least one strut assembly being rotatably connected to the valve closure member on each side of the hinge point of the valve closure member.

Dollison, W.W.

1992-09-08

287

Geometry of aortic heart valves. [prosthetic design  

NASA Technical Reports Server (NTRS)

Photogrammetric measurements of the surface topography of the aortic valves obtained from silicon rubber molds of freshly excised human aortic valves are presented. The data are part of an investigation into the design of a new prosthetic valve which will be a central-flow device, like the real valve and unlike previous central-occluding prostheses. Since the maximum stress on the heart valve is induced when the valve is closed and subject to diastolic back-pressure, it was decided to determine the valve geometry during diastole. That is, the molds were formed by pouring the rubber down the excised aortas, causing the valves to close. The molds were made under different pressures (20-120 torr); photogrammetry served as a vehicle for the assessment of the mold topography through the following outputs: digital models, surface profiles, and contour maps.

Karara, H. M.

1975-01-01

288

Mechanics of the mitral valve  

PubMed Central

Alterations in mitral valve mechanics are classical indicators of valvular heart disease, such as mitral valve prolapse, mitral regurgitation, and mitral stenosis. Computational modeling is a powerful technique to quantify these alterations, to explore mitral valve physiology and pathology, and to classify the impact of novel treatment strategies. The selection of the appropriate constitutive model and the choice of its material parameters are paramount to the success of these models. However, the in vivo parameters values for these models are unknown. Here we identify the in vivo material parameters for three common hyperelastic models for mitral valve tissue, an isotropic one and two anisotropic ones, using an inverse finite element approach. We demonstrate that the two anisotropic models provide an excellent fit to the in vivo data, with local displacement errors in the sub-millimeter range. In a complementary sensitivity analysis, we show that the identified parameter values are highly sensitive to prestrain, with some parameters varying up to four orders of magnitude. For the coupled anisotropic model, the stiffness varied from 119,021kPa at 0% prestrain via 36kPa at 30% prestrain to 9kPa at 60% prestrain. These results may, at least in part, explain the discrepancy between previously reported ex vivo and in vivo measurements of mitral leaflet stiffness. We believe that our study provides valuable guidelines for modeling mitral valve mechanics, selecting appropriate constitutive models, and choosing physiologically meaningful parameter values. Future studies will be necessary to experimentally and computationally investigate prestrain, to verify its existence, to quantify its magnitude, and to clarify its role in mitral valve mechanics. PMID:23263365

Rausch, Manuel K.; Famaey, Nele; Shultz, Tyler OBrien; Bothe, Wolfgang; Miller, D. Craig

2013-01-01

289

Lumped parameter modeling and analysis of hybrid magnet engine valve actuator  

Microsoft Academic Search

The hybrid magnet engine valve actuator (HMEVA) composed of two types of magnets (permanent magnet and electromagnet) and\\u000a two balanced springs is a promising tool for implementing innovative engine management strategies for variable valve timing.\\u000a Finite Element Method (FEM), a favored actuator design tool due to its high accuracy, was utilized to analyze the electromagnetic\\u000a actuator, but it consumes a

Duc Thuan Vu; Young Choi; Jinho Kim

2010-01-01

290

Right-sided valve disease.  

PubMed

In this review, we discuss right-sided heart valve disease, namely tricuspid regurgitation (TR), tricuspid stenosis, pulmonary regurgitation, pulmonary stenosis and right-sided endocarditis. These are frequently seen in conjunction with other diseases, making assessment of their significance more difficult, but it has become increasingly clear that moderate or severe right-sided heart valve disease, in particular TR, is associated with worse prognosis. There remain large gaps in our knowledge of medical and interventional treatment, but in this article we outline what is known about the causes, presentation and management of these commonly seen conditions. PMID:25269950

Coffey, S; Rayner, J; Newton, J; Prendergast, B D

2014-10-01

291

Organic Evaporator steam valve failure  

SciTech Connect

DWPF Technical has requested an analysis of the capacity of the organic Evaporator (OE) condenser (OEC) be performed to determine its capability in the case where the OE steam flow control valve fails open. Calculations of the OE boilup and the OEC heat transfer coefficient indicate the OEC will have more than enough capacity to remove the heat at maximum OE boilup. In fact, the Salt Cell Vent Condenser (SCVC) should also have sufficient capacity to handle the maximum OE boilup. Therefore it would require simultaneous loss of OEC and/or SCVC condensing capacity for the steam valve failure to cause high benzene in the Process Vessel Vent System (PVVS).

Jacobs, R. A.

1992-09-29

292

Force balanced EGR valve with position feedback  

SciTech Connect

An EGR valve is described for an engine comprising: means for mounting the valve to an engine; housing means supported by the mounting means; diaphragm-piston assembly supported by the housing means; a plate supported at its outer periphery by the housing means; the flexible diaphragm having an outer portion supported by the plate; and biasing means supported within the housing means for urging the piston means into the housing and for urging the valve closure element upon the valve seat.

Cook, J.E.; Cook, J.E.

1987-05-05

293

Anterior urethral valve associated with posterior urethral valves.  

PubMed

The association of anterior urethral valve (AUV) with posterior urethral valve (PUV) is rare. A 7-month-old infant was presented at a district hospital with episodes of acute pyelonephritis. He was treated medically and a voiding cystourethrogram (VCUG) confirmed bilateral vesico-urethral reflux. The presence of concomitant AUV and PUV was not recognized. He underwent several surgical procedures, which failed. He had reflux recurrence following two antireflux procedures. He had urinary retention after each operation, which was managed by vesicostomy and perineal urethrostomy. At the age of 3.5 years, he was referred to our paediatric urology clinic. Noticing the AUV and PUV in the past VCUG, the valves were fulgurated. Urodynamic study before and 3 months after valve ablation showed a high voiding pressure. VCUG 6 months following ablation showed no reflux, but several uroflowmetric studies showed a staccato and interrupted pattern. Empirical treatment with an alpha-blocker was started. One year after treatment, a repeat VCUG showed no reflux. Uroflowmetry and urodynamic studies returned to normal. The perineal urethrostomy was closed. The child was asymptomatic after 9 months of follow up. PMID:18947585

Kajbafzadeh, A M; Jangouk, P; Ahmadi Yazdi, C

2005-12-01

294

Aerodynamic Characteristics of Tracheostomy Speaking Valves.  

ERIC Educational Resources Information Center

Pressure-flow characteristics were determined for four different one-way valves (Kisner, Montgomery, Olympic, and Passy-Muir) used for speech production in tracheotomy patients. Results indicated significant differences in resistance among the valves, with the resistance of one valve substantially greater than that of the normal upper airways.

Fornataro-Clerici, Lisa; Zajac, David J.

1993-01-01

295

How Is Mitral Valve Prolapse Treated?  

MedlinePLUS

... is less likely than replacement to weaken the heart. Repair also lowers the risk of infection and decreases the need for lifelong use of blood-thinning medicines. If repair isn't an option, the valve can be replaced. Mechanical and biological valves are used as replacement valves. ...

296

CONTROL VALVE TESTING PROCEDURES AND EQUATIONS  

E-print Network

APPENDIX A CONTROL VALVE TESTING PROCEDURES AND EQUATIONS FOR LIQUID FLOWS #12;APPENDIX A CONTROL in this report is per Instrument Society of America S39.2 testing specifications for control valves. The main. At #12;APPENDIX A CONTROL VALVE TESTING PROCEDURES AND EQUATIONS FOR LIQUID FLOWS 3 Cv d = Cv d 1+ 0

Rahmeyer, William J.

297

Dynamic Testing of Check Valves William Rahmeyer  

E-print Network

Dynamic Testing of Check Valves William Rahmeyer Professor of Civil and Environmental Engineering;1 DYNAMIC FLOW TESTING OF CHECK VALVES by William Rahmeyer, Professor of Civil and Environmental Engineering objectives of this paper are: (1) to present a test method by which check valves can be dynamically tested

Rahmeyer, William J.

298

Valve for fuel pin loading system  

DOEpatents

A cyclone valve surrounds a wall opening through which cladding is projected. An axial valve inlet surrounds the cladding. Air is drawn through the inlet by a cyclone stream within the valve. An inflatable seal is included to physically engage a fuel pin subassembly during loading of fuel pellets.

Christiansen, D.W.

1984-01-01

299

Tricuspid valve regurgitation following blunt thoracic trauma.  

PubMed

Valvular lesions following blunt thoracic trauma are uncommon. Tricuspid valve regurgitation occurs very rarely. We report a successful tricuspid valve reconstruction for rupture of the chordae tendineae in a young man nine years after a motor vehicle accident. The value of echocardiography and transesophageal echocardiography for the diagnosis and quantification of this valve lesion is stressed. PMID:1395792

Kleikamp, G; Schnepper, U; Krtke, H; Breymann, T; Krfer, R

1992-10-01

300

Bicuspid aortic valve syndrome: heterogeneous but predictable?  

Microsoft Academic Search

Bicuspid aortic valve (BAV) has long been associated with a spectrum of vascular complications such as ascending aortic dilatation, aortic aneurysms, and catastrophic aortic root dissec- tion. The mechanism responsible for the associated vascular complications in this seemingly benign and common congenital lesion of aortic valve morphology remains controversial. Some argue that flow dynamics from the mis-shapen outflow valve result

Paul W. M. Fedak

2008-01-01

301

Valve for fuel pin loading system  

DOEpatents

A cyclone valve surrounds a wall opening through which cladding is projected. An axial valve inlet surrounds the cladding. Air is drawn through the inlet by a cyclone stream within the valve. An inflatable seal is included to physically engage a fuel pin subassembly during loading of fuel pellets.

Christiansen, David W. (Kennewick, WA)

1985-01-01

302

The use of MAVIS II to integrate the modeling and analysis of explosive valve interactions  

SciTech Connect

The MAVIS II computer program provides for the modeling and analysis of explosive valve interactions. This report describes the individual components of the program and how MAVIS II is used with other available tools to integrate the design and understanding of explosive valves. The rationale and model used for each valve interaction is described. Comparisons of the calculated results with available data have demonstrated the feasibility and accuracy of using MAVIS II for analytical studies of explosive valve interactions. The model used for the explosive or pyrotechnic used as the driving force in explosive valves is the most critical to be understood and modeled. MAVIS II is an advanced version that incorporates a plastic, as well as elastic, modeling of the deformations experienced when plungers are forced into a bore. The inclusion of a plastic model has greatly expanded the use of MAVIS for all categories (opening, closure, or combined) of valves, especially for the closure valves in which the sealing operation requires the plastic deformation of either a plunger or bore over a relatively large area. In order to increase its effectiveness, the use of MAVIS II should be integrated with the results from available experimental hardware. Test hardware such as the Velocity Interferometer System for Any Reflector (VISAR) and Velocity Generator test provide experimental data for accurate comparison of the actual valve functions. Variable Explosive Chamber (VEC) and Constant Explosive Volume (CEV) tests are used to provide the proper explosive equation-of-state for the MAVIS calculations of the explosive driving forces. The rationale and logistics of this integration is demonstrated through an example. A recent valve design is used to demonstrate how MAVIS II can be integrated with experimental tools to provide an understanding of the interactions in this valve.

Ng, R.; Kwon, D.M.

1998-12-31

303

Delayed depolarization of the cog-wheel valve and pulmonary-to-systemic shunting in alligators.  

PubMed

Alligators and other crocodilians have a cog-wheel valve located within the subpulmonary conus, and active closure of this valve during each heart beat can markedly and phasically increase resistance in the pulmonary outflow tract. If this increased resistance causes right ventricular pressure to rise above that in the systemic circuit, right ventricular blood can flow into the left aorta and systemic circulation, an event known as pulmonary-to-systemic shunting. To understand better how this valve is controlled, anaesthetized American alligators (Alligator mississippiensis) were used to examine the relationships between depolarization of the right ventricle, depolarization/contraction of the cog-wheel valve muscle and the resultant right ventricular, pulmonary artery and systemic pressures. Depolarization swept across the right ventricle from the apex towards the base (near where the cog-wheel valve muscle is located) at a velocity of 91+/-23 cm s(-1) (mean +/- S.E.M., N=3). The cog-wheel valve electrocardiogram (ECG) (and thus contraction of the valve) trailed the right ventricular ECG by 248+/-28 ms (N=3), which was equivalent to 6-35 % of a cardiac cycle. This long interval between right ventricular and valve depolarization suggests a nodal delay at the junction between the base of the right ventricle and the cog-wheel valve. The delay before valve closure determined when the abrupt secondary rise in right ventricular pressure occurred during systole and is likely to strongly influence the amount of blood entering the pulmonary artery and thus to directly control the degree of shunting. Left vagal stimulation (10-50 Hz) reduced the conduction delay between the right ventricle and cog-wheel valve by approximately 20 % and reduced the integrated cog-wheel ECG by 10-20 %. Direct application of acetylcholine (1-2 mg) also reduced the integrated cog-wheel ECG by 10-100 %; however, its effect on the conduction delay was highly variable (-40 to +60 %). When the cog-wheel valve muscle was killed by the application of ethanol, the cog-wheel ECG was absent, right ventricular and pulmonary pressures remained low and tracked one another, the secondary rise in right ventricular pressure was abolished and shunting did not occur. This study provides additional, direct evidence that phasic contraction of the cog-wheel valve muscle controls shunting, that nervous and cholinergic stimulation can alter the delay and strength of valve depolarization and that this can affect the propensity to shunt. PMID:12077160

Syme, Douglas A; Gamperl, Kurt; Jones, David R

2002-07-01

304

Microprocessor-Based Valved Controller  

NASA Technical Reports Server (NTRS)

New controller simpler, more precise, and lighter than predecessors. Mass-flow controller compensates for changing supply pressure and temperature such as occurs when gas-supply tank becomes depleted. By periodically updating calculation of mass-flow rate, controller determines correct new position for valve and keeps mass-flow rate nearly constant.

Norman, Arnold M., Jr.

1987-01-01

305

Pressure compensated flow control valve  

Microsoft Academic Search

The invention is an air flow control valve which is capable of maintaining a constant flow at the outlet despite changes in the inlet or outlet pressure. The device consists of a shell assembly with an inlet chamber and outlet chamber separated by a separation plate. The chambers are connected by an orifice. Also located within the inlet chamber is

Minteer; Daniel J

1999-01-01

306

Bicuspid aortic valve is heritable  

Microsoft Academic Search

ObjectivesPrevious studies have established familial clustering of bicuspid aortic valve (BAV), presumably indicating genetic inheritance. Our objective was to statistically test whether the segregation pattern of BAV is consistent with genetic inheritance and to obtain an estimate of the size of the genetic effect (heritability).

Linda Cripe; Gregor Andelfinger; Lisa J. Martin; Kerry Shooner; D. Woodrow Benson

2004-01-01

307

Dual motion valve with single motion input  

NASA Technical Reports Server (NTRS)

A dual motion valve includes two dual motion valve assemblies with a rotary input which allows the benefits of applying both rotary and axial motion to a rotary sealing element with a plurality of ports. The motion of the rotary sealing element during actuation provides axial engagement of the rotary sealing element with a stationary valve plate which also has ports. Fluid passages are created through the valve when the ports of the rotary sealing element are aligned with the ports of the stationary valve plate. Alignment is achieved through rotation of the rotary sealing element with respect to the stationary valve plate. The fluid passages provide direct paths which minimize fluid turbulence created in the fluid as it passes through the valve.

Belew, Robert (inventor)

1987-01-01

308

Dynamic behavior of valves with pneumatic chamber for reciprocating compressors  

SciTech Connect

This paper describes the dynamic behavior of valves with pneumatic chambers for reciprocating compressors. These are known as `damped valves` and are capable of reducing the impact on the valve seat and valve stopper. The characteristics of the dynamic behavior of the damped valves were clarified by calculating newly derived governing equations of valve dynamics. From the calculated results, it becomes apparent that the volume of the pneumatic chambers and the clearance between the pneumatic chamber and the valve have a large influence on the impact speed of the valves. Furthermore, the valves tend to close later for a higher compressor speed to oscillate at a larger amplitude for a lower density of gas such as hydrogen. These tendencies show that the selection of the specification of damped valves is very important. The stiffness of the valve spring and the lift of the valve also affect valve behavior as with valves without pneumatic chambers.

Kato, M.; Kurohashi, M.; Aoshima, M. [Kobe Steel, Ltd., Kobe (Japan)

1993-10-01

309

Transcatheter aortic valve implantation (TAVI): valve design and evolution.  

PubMed

The efficacy of transcatheter aortic valve implantation (TAVI) in high surgical risk and inoperable patients with severe aortic stenosis (AS) is rapidly gaining credibility with an ever-expanding body of supporting evidence. The potential of TAVI to be a treatment option for a significant cohort of patients with aortic stenosis has fuelled a drive for the optimum device and resulted in exponential advances in the technology with a focus on adverse event minimization and procedural simplification. Consequently, a plethora of new transcatheter valve choices are now available for clinical study or in the pipeline. The evaluation of past, current and emerging devices allows for an appreciation of the design considerations involved in this process and an insight to the future direction of the technology. PMID:23972363

Fanning, Jonathon P; Platts, David G; Walters, Darren L; Fraser, John F

2013-10-01

310

Are bicuspid aortic valves a limitation for aortic valve repair?  

Microsoft Academic Search

Objective: To compare the mid-term results after aortic valve (AV) repair in bicuspid AVs with those in tricuspid AVs. Methods: Between 2000 and 2010, 100 patients (mean age 47.2 years) underwent AV repair procedures for insufficient bicuspid AV (n=43) and tricuspid AV (n=57). Aortic regurgitation (AR) more than moderate was present in 31\\/43 and 21\\/57 patients in the bicuspid AV

Catalin C. Badiu; Sabine Bleiziffer; Walter B. Eichinger; Iva Zaimova; Andrea Hutter; Domenico Mazzitelli; Bernhard Voss; Rdiger Lange

2011-01-01

311

Transcatheter Aortic Valve Implantation in a Patient with Previous Mitral Valve Replacement  

PubMed Central

Transcatheter aortic valve implantation (TAVI) has shown favorable outcomes in patients with severe symptomatic aortic valve stenosis who are at high surgical risk or are unsuitable candidates for open heart surgery. However, concerns exist over treating patients who have previously undergone mitral valve surgery due to the potential interference between the mitral prosthetic valve or ring and the TAVI device. In this case report, we present a patient with symptomatic severe aortic stenosis and previous mechanical mitral valve replacement who was successfully treated with TAVI using a CoreValve.

Moon, Sung Woo; Ko, Young-Guk; Hong, Geu-Ru; Lee, Sak; Chang, Byung-Chul; Shim, Jae-Kwang; Kwak, Young-Ran

2014-01-01

312

Transcatheter aortic valve implantation in a patient with previous mitral valve replacement.  

PubMed

Transcatheter aortic valve implantation (TAVI) has shown favorable outcomes in patients with severe symptomatic aortic valve stenosis who are at high surgical risk or are unsuitable candidates for open heart surgery. However, concerns exist over treating patients who have previously undergone mitral valve surgery due to the potential interference between the mitral prosthetic valve or ring and the TAVI device. In this case report, we present a patient with symptomatic severe aortic stenosis and previous mechanical mitral valve replacement who was successfully treated with TAVI using a CoreValve. PMID:25278988

Moon, Sung Woo; Ko, Young-Guk; Hong, Geu-Ru; Lee, Sak; Chang, Byung-Chul; Shim, Jae-Kwang; Kwak, Young-Ran; Hong, Myeong-Ki

2014-09-01

313

Leakage test during mitral valve repair.  

PubMed

Mitral valve repair is the preferred surgical treatment for mitral regurgitation. Cardiac surgeons must increasingly pursue high-quality mitral valve repair, which ensures excellent long-term outcomes. Intraoperative assessment of a competency of the repaired mitral valve before closure of the atrium is an important step in accomplishing successful mitral valve repair. Saline test is the most simple and popular method to evaluate the repaired valve. In addition, an "Ink test" can provide confirmation of the surface of coaptation, which is often insufficient in the assessment of saline test. There are sometimes differences between the findings of the leakage test in an arrested heart and the echocardiographic findings after surgery. Assessment of the mitral valve in an arrested heart may not accurately reflect its function in a contractile heart. Assessment of the valve on the beating heart induced by antegrade or retrograde coronary artery perfusion can provide a more physiological assessment of the repaired valve. Perfusion techniques during beating heart surgery mainly include antegrade coronary artery perfusion without aortic cross-clamping, and retrograde coronary artery perfusion via the coronary sinus with aortic cross-clamping. It is the most important point for the former approach to avoid air embolism with such precaution as CO2 insufflation, left ventricular venting, and transesophageal echocardiography, and for the latter approach to maintain high perfusion flow rate of coronary sinus and adequate venting. Leakage test during mitral valve repair increasingly takes an important role in successful mitral valve reconstruction. PMID:25156036

Watanabe, Taiju; Arai, Hirokuni

2014-11-01

314

Thermostatic Valves Containing Silicone-Oil Actuators  

NASA Technical Reports Server (NTRS)

Flow-splitting and flow-mixing thermally actuated spool valves have been developed for controlling flows of a heat-transfer fluid in a temperature-regulation system aboard the Mars Science Laboratory (MSL) rover. Valves like these could also be useful in terrestrial temperature-regulation systems, including automobile air-conditioning systems and general refrigeration systems. These valves are required to provide smoother actuation over a wider temperature range than the flow-splitting, thermally actuated spool valves used in the Mars Explorer Rover (MER). Also, whereas the MER valves are unstable (tending to oscillate) in certain transition temperature ranges, these valves are required not to oscillate. The MER valves are actuated by thermal expansion of a wax against spring-loaded piston rods (as in common automotive thermostats). The MSL valves contain similar actuators that utilize thermal expansion of a silicone oil, because silicone-oil actuators were found to afford greater and more nearly linear displacements, needed for smoother actuation, over the required wider temperature range. The MSL valves also feature improved spool designs that reflect greater understanding of fluid dynamics, consideration of pressure drops in valves, and a requirement for balancing of pressures in different flow branches.

Bhandari, Pradeep; Birur, Gajanana C.; Bame, David P.; Karlmann, Paul B.; Prina, Mauro; Young, William; Fisher, Richard

2009-01-01

315

Aerosol penetration through respirator exhalation valves.  

PubMed

Exhalation valves are a critical component of industrial respirators. They are designed to permit minimal inward leakage of air contaminants during inhalation and provide low resistance during exhalation. Under normal conditions, penetration of aerosol through exhalation valves is minimal. The exhalation valve is, however, a vulnerable component of a respirator and under actual working conditions may become dirty or damaged to the point of causing significant leakage. Aerosol penetration was measured for normal exhalation valves and valves compromised by paint or fine copper wires on the valve seat. Penetration increased with increasing wire diameter. A wire 250 microns in diameter allowed greater than 1% penetration into the mask cavity. Dirt or paint accumulated on the exhalation valve allowed a similar level of penetration. Work rate had little effect on observed penetration. Penetration decreased significantly with increasing aerosol particle size. The amount of material on the valve or valve seat necessary for significant (greater than 0.5%) inward leakage in a half-mask respirator could be readily observed by careful inspection of the exhalation valve and its seat in good lighting conditions. PMID:2147535

Bellin, P; Hinds, W C

1990-10-01

316

Congenital unicuspid aortic valve stenosis in siblings.  

PubMed

We reported the case of unicuspid aortic valve in sibling, suggesting the familial incidence and genetic relation. A 41-year-old man (elder brother) with 79mmHg of aortic valvular peak pressure gradient (peak PG) underwent aortic valve replacement with mechanical prosthetic valve (ATS 21mm). The intraoperative finding showed the unicuspid aortic valve with one rudimentary commissure. A 37-year-old woman (sister) had been followed by echocardiography as bicuspid aortic valve since 10years old. After 27years, the peak PG had increased to 176mmHg on preoperative echocardiography. The aortic valve replacement was performed. The bioprosthetic valve (MOSAIC 21mm) was implanted supra-annularly because the patient required pregnancy. The intraoperative finding showed the unicuspid aortic valve with two rudimentary commissures and one opening of LCC-RCC commissure. The histopathological study of both patients confirmed as congenitally unicuspid aortic valve. In our best knowledge, this is a first report of unicuspid aortic valve in sibling. PMID:23709159

Kawahara, Yu; Suzuki, Kotarou; Takahara, Shingo; Fukasawa, Manabu

2014-09-01

317

Liquid crystal light valve structures  

NASA Technical Reports Server (NTRS)

An improved photosensor film and liquid crystal light valves embodying said film is provided. The photosensor film and liquid crystal light valve is characterized by a significant lower image retention time while maintaining acceptable photosensitivity. The photosensor film is produced by sputter depositing CdS onto an ITO substrate in an atmosphere of argon/H2S gas while maintaining the substrate at a temperature in the range of about 130 C to about 200 C and while introducing nitrogen gas into the system to the extent of not more than about 1% of plasma mixture. Following sputter deposition of the CdS, the film is annealed in an inert gas at temperatures ranging from about 300 C to about 425 C.

Koda, N. J. (inventor)

1985-01-01

318

Pressure/vacuum relief valve  

SciTech Connect

This patent describes a pressure/vacuum relief valve for a fluid containing vessel. It comprises: an elongated cylinder having a wall and having end walls closing the cylinder ends, one end portion of the cylinder wall having a first port communicating with the fluid in the vessel and the other end portion of the cylinder having a second port communicating with the atmosphere; a piston in the cylinder normally sealed with the inner wall surface thereof between the first and second ports; a piston rod axially projecting from the piston through the respective cylinder end wall; elongated cage means having a closed end and an open end axially connected with the respective cylinder end wall around the respective end portion of the piston rod; and, pressure responsive elongated pin means interposed between the respective end of the piston rod and the closed end of the respective cage for normally maintaining the piston in valve closed position.

Taylor, J.S.

1990-12-18

319

Mechanical Prosthetic Valves and Pregnancy  

PubMed Central

Choosing the best anticoagulant therapy for a pregnant patient with a mechanical prosthetic valve is controversial and the published international guidelines contain no clear-cut consensus on the best approach. This is due to the fact that there is presently no anticoagulant which can reliably decrease thromboembolic events while avoiding damage to the fetus. Current treatments include either continuing oral warfarin or substituting warfarin for subcutaneous unfractionated heparin or low-molecular-weight heparin (LMWH) in the first trimester (612 weeks) or at any point throughout the pregnancy. However, LMWH, while widely-prescribed, requires close monitoring of the blood anti-factor Xa levels. Unfortunately, facilities for such monitoring are not universally available, such as within hospitals in developing countries. This review evaluates the leading international guidelines concerning anticoagulant therapy in pregnant patients with mechanical prosthetic valves as well as proposing a simplified guideline which may be more relevant to hospitals in this region. PMID:25364545

Panduranga, Prashanth; El-Deeb, Mohammed; Jha, Chitra

2014-01-01

320

Organic evaporator steam valve failure  

SciTech Connect

Defense Waste Processing Facility (DWPF) Technical has requested an analysis of the capacity of the Organic Evaporator (OE) condenser (OEC) be performed to determine its capability in the case where the OE steam flow control valve fails open. Calculations of the OE boilup and the OEC heat transfer coefficient indicate the OEC will have more than enough capacity to remove the heat at maximum OE boilup. In fact, the Salt Cell Vent Condenser (SCVC) should also have sufficient capacity to handle the maximum OE boilup. Therefore, it would require simultaneous loss of OEC and/or SCVC condensing capacity for the steam valve failure to cause high benzene in the Process Vessel Vent System (PVVS).

Jacobs, R.A.

1992-09-29

321

Introduction of particle plug valve  

Microsoft Academic Search

In this paper, experiments are carried out for three Geldart-D powders in three conical fluidized beds and the hopperstandpipe system. Based on these experimental data, the hopperstandpipe system, which is used to maintain the large pressure drop without the motion of particles when the flow of particles is cut off, is called particle plug valve (PPV) and the method for

Shan Jing; Qingyuan Hu; Guobin Cai; Jinfu Wang; Yong Jin

2001-01-01

322

Removed shunt valves: reasons for failure and implications for valve design.  

PubMed

Most removed shunt valves are discarded with no investigation into why they had to be replaced or whether they still performed to specification. However, improvements in valve design will only occur if valves that have needed removal are examined and the reasons that they failed are determined. An in-depth study of 43 valves that were removed in this unit over a 15-month period was performed. They were submitted to a four-part study, comprising flow-pressure testing, opening and closing pressure measurement, assessment of the susceptibility to syphoning, and dismantling with internal inspection of the valve components. Overall, 81% of valves failed to meet the manufacturers' specified performance data, even though the peroperative cause of shunt failure was thought to lie outside the valve. Over 80% of valves with metallic parts were found to have accumulated debris internally, and this was thought to have impaired their performance. In contrast, only 25% of non-metallic valves contained debris, a significant difference (0.01 > p > 0.001). All of the valves had a high tendency to overdrainage. Attention is drawn to the high number of malfunctioning valves. It is recommended that a change of valve should be considered in all shunt revisions, and that future valve designs should avoid metal components. PMID:8799534

Brydon, H L; Bayston, R; Hayward, R; Harkness, W

1996-06-01

323

Miniature electrically operated diaphragm valve  

DOEpatents

The present invention provides a miniature electrically operated valve that can stand off significant pressures, that can be inexpensively produced, and that can be made to operate without continuous electrical power. A valve according to the present invention comprises a housing and a beam mounted with the housing. A diaphragm mounted with the housing forms a sealed fluid volume. An electromagnetic energy source, such as an electromagnetic coil, mounts with the housing and when energized urges the beam in one direction. The beam can be urged in the opposing direction by passive means or by reversing the polarity of the electromagnetic energy source or by a second electromagnetic energy source. Two fluid ports mount with the housing. A first fluid port mounts so that, as the beam is urged in one direction or the opposite, the beam urges the diaphragm to move between engaging and substantially sealing the fluid port and disengaging and not substantially sealing the fluid port. A seat can be mounted with the diaphragm to aid in sealing the fluid port. Latching mechanisms such as permanent magnets can be mounted so that the valve remains in the open or closed positions without continuous electrical power input. Fluid can flow through the housing between the two fluid ports when the diaphragm does not seal the first fluid port, but can be prevented from flowing by urging the beam so that the diaphragm seals the first fluid port. Various embodiments accommodate various latching mechanisms, electromagnetic energy sources, number of fluid ports, and diaphragm design considerations.

Adkins, Douglas R. (Albuquerque, NM); Spletzer, Barry L. (Albuquerque, NM); Wong, Chungnin C. (Albuquerque, NM); Frye-Mason, Gregory C. (Cedar Crest, NM); Fischer, Gary J. (Albuquerque, NM); Hesketh, Peter J. (Atlanta, GA)

2001-01-01

324

Vascularization of bioprosthetic valve material  

NASA Astrophysics Data System (ADS)

Cell membrane remnants represent a probable nucleation site for calcium deposition in bioprosthetic heart valves. Calcification is a primary failure mode of both bovine pericardial and porcine aortic heterograft bioprosthesis but the nonuniform pattern of calcium distribution within the tissue remains unexplained. Searching for a likely cellular source, we considered the possibility of a previously overlooked small blood vessel network. Using a videomicroscopy technique, we examined 5 matched pairs of porcine aortic and pulmonary valves and 14 samples from 6 bovine pericardia. Tissue was placed on a Leitz Metallux microscope and transilluminated with a 75 watt mercury lamp. Video images were obtained using a silicon intensified target camera equipped with a 431 nm interference filter to maximize contrast of red cells trapped in a capillary microvasculature. Video images were recorded for analysis on a Silicon Graphics Image Analysis work station equipped with a video frame grabber. For porcine valves, the technique demonstrated a vascular bed in the central spongiosa at cusp bases with vessel sizes from 6-80 micrometers . Bovine pericardium differed with a more uniform distribution of 7-100 micrometers vessels residing centrally. Thus, small blood vessel endothelial cells provide a potential explanation patterns of bioprosthetic calcification.

Boughner, Derek R.; Dunmore-Buyze, Joy; Heenatigala, Dino; Lohmann, Tara; Ellis, Chris G.

1999-04-01

325

Force measuring valve assemblies, systems including such valve assemblies and related methods  

DOEpatents

Methods of evaluating a fluid condition may include stroking a valve member and measuring a force acting on the valve member during the stroke. Methods of evaluating a fluid condition may include measuring a force acting on a valve member in the presence of fluid flow over a period of time and evaluating at least one of the frequency of changes in the measured force over the period of time and the magnitude of the changes in the measured force over the period of time to identify the presence of an anomaly in a fluid flow and, optionally, its estimated location. Methods of evaluating a valve condition may include directing a fluid flow through a valve while stroking a valve member, measuring a force acting on the valve member during the stroke, and comparing the measured force to a reference force. Valve assemblies and related systems are also disclosed.

DeWall, Kevin George (Pocatello, ID); Garcia, Humberto Enrique (Idaho Falls, ID); McKellar, Michael George (Idaho Falls, ID)

2012-04-17

326

Transatrial transcatheter tricuspid valve-in-valve implantation of balloon expandable bioprosthesis.  

PubMed

Transcatheter valve-in-valve implantation into failing mitral and aortic bioprosthetic valves have been reported. This strategy avoids performing high-risk repeat cardiac surgery in elderly patients with multiple comorbidities. Tricuspid valve-in-valve implantation has not been described. We report a case of failing bioprosthetic tricuspid valve in a 48-year-old woman with carcinoid syndrome. We attempted a transatrial transcatheter approach and we successfully deployed a 26-mm Edwards Sapien balloon expandable bioprosthesis (Edwards Lifesciences, Irvine, CA) into a severely stenotic tricuspid bioprosthesis. This case demonstrates the technical feasibility and safety of this approach. Therefore, tricuspid valve-in-valve implantation may be a viable treatment alternative in carefully selected patients. PMID:20971296

Hon, Jimmy Kim Fatt; Cheung, Anson; Ye, Jian; Carere, Ronald G; Munt, Brad; Josan, Kiranbir; Lichtenstein, Samuel V; Webb, John

2010-11-01

327

Bistable (latching) solenoid actuated propellant isolation valve  

NASA Technical Reports Server (NTRS)

The design, fabrication, assembly and test of a development configuration bistable (latching) solenoid actuated propellant isolation valve suitable for the control hydrazine and liquid fluorine to an 800 pound thrust rocket engine is described. The valve features a balanced poppet, utilizing metal bellows, a hard poppet/seat interface and a flexure support system for the internal moving components. This support system eliminates sliding surfaces, thereby rendering the valve free of self generated particles.

Wichmann, H.; Deboi, H. H.

1979-01-01

328

Aortic valve regurgitation and the congenitally bicuspid aortic valve: a clinico-pathological correlation  

Microsoft Academic Search

OBJECTIVE--To investigate the morphology of congenitally bicuspid aortic valves causing pure valve regurgitation. DESIGN--A case series collected over five years. SETTING--An academic hospital. PATIENTS AND METHODS--One hundred and forty eight excised congenitally bicuspid aortic valves. The morphological findings were correlated with sex, age, clinical history, and data on haemodynamic function before operation. Pure valve regurgitation was defined as grade 3-4\\/4

A S Sadee; A E Becker; H A Verheul; B Bouma; G Hoedemaker

1992-01-01

329

Solve valve noise and cavitation problems  

SciTech Connect

A clear understanding of aerodynamic noise theory and cavitation will avoid most major valve problems in process plants and allow the valve engineer to design out potential problems. On the other hand, the plant owner has to recognize that such valves may require a cost premium. However, such a premium will be recovered in a small amount of time because of the savings from reduced downtime and lower maintenance costs. Pressure reducing valves used on gases or high pressure steam valves, such as turbine bypass valves, convert substantial energy into heat and a lower pressure level. Unfortunately, this can only be done by accelerating the gas in one or more orifices and then decelerating it rapidly again through a turbulence mechanism or super-sonic shock cells. This causes a lot of noise and vibration. Valve engineering science has made substantial strides in the past few years, and one is now able to predict cavitation and aerodynamic sound levels before a valve is purchased. Similarly, newer valve sizes incorporate features that reduce noise and cavitation effects. Some other minor problems are resonant plug vibration and flashing. The paper discusses how to predict aerodynamic sound, how close can one estimate the sound level, cavitation, and incorrect installation.

Baumann, H.D. [Fisher Controls International, Inc., St. Louis, MO (United States)

1997-03-01

330

Current Status of Prosthetic Cardiac Valves  

PubMed Central

The majority of patients with acquired valvular heart disease have severe damage to valves which is not amenable to repair but can now be treated by valve replacement with an acceptable mortality and morbidity. The caged ball or disc valve is widely used and is proving clinically satisfactory for cardiac valve replacement. Thromboembolism is the significant complication. With improvement in technique the incidence of infection, detachment and other complications has been reduced. ImagesFigure 1.Figure 2.Figure 4.Figure 5.Figure 6.Figure 7.Figure 8.Figure 9.Figure 10. PMID:6039188

Huse, Wilfred M.; Wareham, Ellsworth E.

1967-01-01

331

In vitro evaluation of right ventricular outflow tract reconstruction with bicuspid valved polytetrafluoroethylene conduit.  

PubMed

Conduits available for right ventricular outflow tract (RVOT) reconstruction eventually become stenotic and/or insufficient due to calcification. In order to reduce the incidence of reoperations we have developed and used a bicuspid valved polytetrafluoroethylene (PTFE) conduit for the RVOT reconstruction. The purpose of this study is to investigate the hemodynamic performance of the new design using a pediatric in vitro right heart mock loop. PTFE conduit has been used for the complete biventricular repair of 20 patients (age 1.76 years) with cyanotic congenital defects. To account for the large variability of conduit sizes, 14, 16, 22, and 24-mm conduit sizes were evaluated using an in vitro flow loop comprised of a pulsatile pump with cardiac output (CO) of 1.2-3.2L/min, bicuspid valved RVOT conduit, pulmonary artery, venous compartments, and the flow visualization setup. We recorded the diastolic valve leakage and pre- and post-conduit pressures in static and pulsatile settings. In vitro valve function and overall hemodynamic performance was evaluated using high-speed cameras and ultrasonic flow probes. Three-dimensional flow fields for different in vivo conduit curvatures and inflow regimes were calculated by computational fluid dynamics (CFD) analysis to further aid the conduit design process. The average pressure drop over the valved conduits was 0.81.7mm Hg for the CO range tested. Typical values for regurgitant fraction, peak-to-peak pressure gradient, and effective office area were 232.1%, 132.4mm Hg, and 1.560.2 cm(2) , respectively. High-speed videos captured the intact valve motion with asymmetrical valve opening during the systole. CFD simulations demonstrated the flow skewness toward the major curvature of the conduit based on the pulmonic curvature. In vitro evaluation of the bicuspid valved PTFE conduit coincides well with acceptable early clinical performance (mild insufficiency), with relatively low pressure drop, and intact valve motion independent from the conduit curvature, orientation or valve location, but at the expense of increased diastolic flow regurgitation. These findings benchmark the baseline performance of the bicuspid valved conduit and will be used for future designs to improve valve competency. PMID:21092044

Dur, Onur; Yoshida, Masahiro; Manor, Philip; Mayfield, Alice; Wearden, Peter D; Morell, Victor O; Pekkan, Kerem

2010-11-01

332

Transcatheter aortic valve implantation in Jehovah's Witness patients with symptomatic severe aortic valve stenosis  

PubMed Central

Transcatheter aortic valve implantation (TAVI) is currently reserved for high or prohibitive surgical-risk patients with aortic valve stenosis. We report on successful TAVI in two Jehovah's witness patients. It offers a simple and effective treatment of severe aortic valve stenosis in high-risk patients who refuse the use of allogeneic blood and blood products. PMID:22753437

Buz, Semih; Pasic, Miralem; Unbehaun, Axel; Hetzer, Roland

2012-01-01

333

Transcatheter aortic valve implantation in Jehovah's Witness patients with symptomatic severe aortic valve stenosis.  

PubMed

Transcatheter aortic valve implantation (TAVI) is currently reserved for high or prohibitive surgical-risk patients with aortic valve stenosis. We report on successful TAVI in two Jehovah's witness patients. It offers a simple and effective treatment of severe aortic valve stenosis in high-risk patients who refuse the use of allogeneic blood and blood products. PMID:22753437

Buz, Semih; Pasic, Miralem; Unbehaun, Axel; Hetzer, Roland

2012-10-01

334

Repositioning of an intraventricular dislocated aortic valve during transcatheter aortic valve implantation.  

PubMed

The case is presented of a 75-year-old man referred for transcatheter aortic valve implantation. During the procedure the prosthetic aortic valve became dislocated into the left ventricle shortly after expansion. The subsequent steps taken to reposition the valve using only materials at hand are described. PMID:25296450

Natour, Ehsan; Douglas, Yvonne L; Jainandunsing, Jayant S; Schurer, Remco A J; van der Werf, Hendrik W; van den Heuvel, Ad F M

2014-05-01

335

21 CFR 870.3925 - Replacement heart valve.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Replacement heart valve. 870.3925 Section 870.3925...Prosthetic Devices 870.3925 Replacement heart valve. (a) Identification. A replacement heart valve is a device intended to perform...

2010-04-01

336

21 CFR 870.3945 - Prosthetic heart valve sizer.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Prosthetic heart valve sizer. 870.3945 Section 870...Prosthetic Devices 870.3945 Prosthetic heart valve sizer. (a) Identification. A prosthetic heart valve sizer is a device used to...

2010-04-01

337

21 CFR 870.3935 - Prosthetic heart valve holder.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Prosthetic heart valve holder. 870.3935 Section 870...Prosthetic Devices 870.3935 Prosthetic heart valve holder. (a) Identification. A prosthetic heart valve holder is a device used to hold...

2010-04-01

338

30. Engine controls and valve gear, looking aft on main ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

30. Engine controls and valve gear, looking aft on main (promenade) deck level. Threaded admission valve lift rods (two at immediate left of chronometer) permit adjustment of valve timing in lower and upper admission valves of cylinder (left rod controls lower valve, right rod upper valve). Valve rods are lifted by jaw-like "wipers" during operation. Exhaust valve lift rods and wipers are located to right of chronometer. Crank at extreme right drives valve wiper shaft when engaged to end of eccentric rod, shown under "Crank Indicator" dial. Pair of handles to immediate left of admission valve rods control condenser water valves; handles to right of exhaust valve rods control feedwater flow to boilers from pumps. Gauges indicate boiler pressure (left) and condenser vacuum (right); "Crank Indicator" on wall aids engineer in keeping engine crank off "dead-center" at stop so that engine may be easily restarted. - Ferry TICONDEROGA, Route 7, Shelburne, Chittenden County, VT

339

All-metal valve structure for gas systems  

DOEpatents

A valve assembly with a resilient metal seat member is disclosed for providing a gas-tight seal in a gas handling system. The valve assembly also includes a valve element for sealing against the valve seat member; and an actuating means for operating the valve element. The valve seat member is a one-piece stainless steel ring having a central valve port and peripheral mounting flange, and an annular corrugation in between. A groove between the first and second ridges serves as a flexure zone during operation of the valve member and thus provides the seating pressure between the inner ridge or valve seat and the valve element. The outer annular ridge has a diameter less than said valve element to limit the seating motion of the valve element, preventing non-elastic deformation of the seat member.

Baker, R.W.; Pawlak, D.A.; Ramey, A.J.

1982-06-10

340

21 CFR 870.3935 - Prosthetic heart valve holder.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Prosthetic heart valve holder. 870.3935 Section 870...Prosthetic Devices 870.3935 Prosthetic heart valve holder. (a) Identification. A prosthetic heart valve holder is a device used to hold...

2013-04-01

341

21 CFR 870.3945 - Prosthetic heart valve sizer.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Prosthetic heart valve sizer. 870.3945 Section 870...Prosthetic Devices 870.3945 Prosthetic heart valve sizer. (a) Identification. A prosthetic heart valve sizer is a device used to...

2012-04-01

342

21 CFR 870.3945 - Prosthetic heart valve sizer.  

...2014-04-01 2014-04-01 false Prosthetic heart valve sizer. 870.3945 Section 870...Prosthetic Devices 870.3945 Prosthetic heart valve sizer. (a) Identification. A prosthetic heart valve sizer is a device used to...

2014-04-01

343

21 CFR 870.3935 - Prosthetic heart valve holder.  

...2014-04-01 2014-04-01 false Prosthetic heart valve holder. 870.3935 Section 870...Prosthetic Devices 870.3935 Prosthetic heart valve holder. (a) Identification. A prosthetic heart valve holder is a device used to hold...

2014-04-01

344

46 CFR 153.980 - Isolation of automatic closing valves.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Isolation of automatic closing valves. 153.980 Section...Procedures 153.980 Isolation of automatic closing valves. The person in charge of cargo transfer may isolate automatic closing valves described in ...

2010-10-01

345

49 CFR 236.837 - Valve, electro-pneumatic.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Valve, electro-pneumatic. 236.837 Section 236.837 Transportation Other...APPLIANCES Definitions 236.837 Valve, electro-pneumatic. A valve electrically operated which, when...

2012-10-01

346

49 CFR 236.837 - Valve, electro-pneumatic.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Valve, electro-pneumatic. 236.837 Section 236.837 Transportation Other...APPLIANCES Definitions 236.837 Valve, electro-pneumatic. A valve electrically operated which, when...

2010-10-01

347

49 CFR 236.837 - Valve, electro-pneumatic.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Valve, electro-pneumatic. 236.837 Section 236.837 Transportation Other...APPLIANCES Definitions 236.837 Valve, electro-pneumatic. A valve electrically operated which, when...

2011-10-01

348

49 CFR 236.837 - Valve, electro-pneumatic.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Valve, electro-pneumatic. 236.837 Section 236.837 Transportation Other...APPLIANCES Definitions 236.837 Valve, electro-pneumatic. A valve electrically operated which, when...

2013-10-01

349

Hydraulic engine valve actuation system including independent feedback control  

SciTech Connect

A hydraulic valve actuation assembly may include a housing, a piston, a supply control valve, a closing control valve, and an opening control valve. The housing may define a first fluid chamber, a second fluid chamber, and a third fluid chamber. The piston may be axially secured to an engine valve and located within the first, second and third fluid chambers. The supply control valve may control a hydraulic fluid supply to the piston. The closing control valve may be located between the supply control valve and the second fluid chamber and may control fluid flow from the second fluid chamber to the supply control valve. The opening control valve may be located between the supply control valve and the second fluid chamber and may control fluid flow from the supply control valve to the second fluid chamber.

Marriott, Craig D

2013-06-04

350

21 CFR 874.3850 - Endolymphatic shunt tube with valve.  

Code of Federal Regulations, 2010 CFR

...Endolymphatic shunt tube with valve. 874.3850 Section...AND THROAT DEVICES Prosthetic Devices 874.3850 Endolymphatic shunt tube with valve. (a) Identification...endolymphatic shunt tube with valve is a device that...

2010-04-01

351

Sliding-Gate Valve for Use with Abrasive Materials.  

National Technical Information Service (NTIS)

The invention is a flow and pressure-sealing valve for use with abrasive solids. The valve embodies special features which provide for long, reliable operating lifetimes in solids-handling service. The valve includes upper and lower transversely slidable ...

W. J. Ayers, C. R. Carter, R. A. Griffith, R. B. Loomis, J. E. Notestein

1982-01-01

352

Isolation of murine valve endothelial cells.  

PubMed

Normal valve structures consist of stratified layers of specialized extracellular matrix (ECM) interspersed with valve interstitial cells (VICs) and surrounded by a monolayer of valve endothelial cells (VECs). VECs play essential roles in establishing the valve structures during embryonic development, and are important for maintaining life-long valve integrity and function. In contrast to a continuous endothelium over the surface of healthy valve leaflets, VEC disruption is commonly observed in malfunctioning valves and is associated with pathological processes that promote valve disease and dysfunction. Despite the clinical relevance, focused studies determining the contribution of VECs to development and disease processes are limited. The isolation of VECs from animal models would allow for cell-specific experimentation. VECs have been isolated from large animal adult models but due to their small population size, fragileness, and lack of specific markers, no reports of VEC isolations in embryos or adult small animal models have been reported. Here we describe a novel method that allows for the direct isolation of VECs from mice at embryonic and adult stages. Utilizing the Tie2-GFP reporter model that labels all endothelial cells with Green Fluorescent Protein (GFP), we have been successful in isolating GFP-positive (and negative) cells from the semilunar and atrioventricular valve regions using fluorescence activated cell sorting (FACS). Isolated GFP-positive VECs are enriched for endothelial markers, including CD31 and von Willebrand Factor (vWF), and retain endothelial cell expression when cultured; while, GFP-negative cells exhibit molecular profiles and cell shapes consistent with VIC phenotypes. The ability to isolate embryonic and adult murine VECs allows for previously unattainable molecular and functional studies to be carried out on a specific valve cell population, which will greatly improve our understanding of valve development and disease mechanisms. PMID:25177896

Miller, Lindsey J; Lincoln, Joy

2014-01-01

353

Cylinder valve packing nut studies  

SciTech Connect

The design, manufacture, and use of cylinder valve packing nuts have been studied to improve their resistance to failure from stress corrosion cracking. Stress frozen photoelastic models have been analyzed to measure the stress concentrations at observed points of failure. The load effects induced by assembly torque and thermal expansion of stem packing were observed by strain gaging nuts. The effects of finishing operations and heat treatment were studied by the strain gage hole boring and X-ray methods. Modifications of manufacturing and operation practices are reducing the frequency of stress corrosion failures.

Blue, S.C. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

1991-12-31

354

Optimization for training neural nets  

Microsoft Academic Search

Various techniques of optimizing criterion functions to train neural-net classifiers are investigated. These techniques include three standard deterministic techniques (variable metric, conjugate gradient, and steepest descent), and a new stochastic technique. It is found that the stochastic technique is preferable on problems with large training sets and that the convergence rates of the variable metric and conjugate gradient techniques are

Etienne Barnard

1992-01-01

355

Bicuspid Aortic Valve Disease and Ascending Aortic Aneurysms: Gaps in Knowledge  

PubMed Central

The bicuspid aortic valve is the most common congenital cardiac anomaly in developed nations. The abnormal bicuspid morphology of the aortic valve results in valvular dysfunction and subsequent hemodynamic derangements. However, the clinical presentation of bicuspid aortic valve disease remains quite heterogeneous with patients presenting from infancy to late adulthood with variable degrees of valvular stenosis and insufficiency and associated abnormalities including aortic coarctation, hypoplastic left heart structures, and ascending aortic dilatation. Emerging evidence suggests that the heterogeneous presentation of bicuspid aortic valve phenotypes may be a more complex matter related to congenital, genetic, and/or connective tissue abnormalities. Optimal management of patients with BAV disease and associated ascending aortic aneurysms often requires a thoughtful approach, carefully assessing various risk factors of the aortic valve and the aorta and discerning individual indications for ongoing surveillance, medical management, and operative intervention. We review current concepts of anatomic classification, pathophysiology, natural history, and clinical management of bicuspid aortic valve disease with associated ascending aortic aneurysms. PMID:23198270

Losenno, Katie L.; Goodman, Robert L.; Chu, Michael W. A.

2012-01-01

356

Control Valve Trajectories for SOFC Hybrid System Startup  

SciTech Connect

Control and management of cathode airflow in a solid oxide fuel cell gas turbine hybrid power system was analyzed using the Hybrid Performance (HyPer) hardware simulation at the National Energy Technology (NETL), U.S. Department of Energy. This work delves into previously unexplored operating practices for HyPer, via simultaneous manipulation of bypass valves and the electric load on the generator. The work is preparatory to the development of a Multi-Input, Multi-Output (MIMO) controller for HyPer. A factorial design of experiments was conducted to acquire data for 81 different combinations of the manipulated variables, which consisted of three air flow control valves and the electric load on the turbine generator. From this data the response surface for the cathode airflow with respect to bypass valve positions was analyzed. Of particular interest is the control of airflow through the cathode during system startup and during large load swings. This paper presents an algorithm for controlling air mass flow through the cathode based on a modification of the steepest ascent method.

Gorrell, Megan; Banta, Larry; Rosen, William; Restrepo, Bernardo; Tucker, David

2012-07-01

357

Disruption of silicone valve housing in a Codman Hakim Precision valve with integrated Siphonguard.  

PubMed

Authors of this report describe 2 patients who had undergone shunt insertion for hydrocephalus and who, at 6 weeks or 9 months after their last revision, presented with symptoms of shunt dysfunction and CSF collections at the valve site. At the ensuing shunt revision in both patients, the silicone housing was fractured and the Siphonguard was disconnected from the Codman Hakim Precision flat-bottom valve. The cause of these failures was not clear since manipulation, bending, and twisting of the valves were not thought to have occurred during implantation. A review of the FDA's Manufacturer and User Facility Device Experience (MAUDE) database revealed 58 cases of silicone housing failure in the Codman Hakim Precision valve with integrated Siphonguard since the year 2000. A single report was found in the databases administered by the Canadian Medical Devices Sentinel Network (CMDSNet). The Codman Hakim Precision valves with integrated Siphonguard are delicate devices that do not withstand the intraoperative handling tolerated by other valves. When these valves are implanted, gentle handling and wide exposures are needed to minimize the risk of valve damage. Valves should be handled according to the manufacturer's instructions. However, in light of this particular pattern of failure, it is recommended that the manufacturer redesign this valve to provide handling tolerance that is characteristic of other valves on the market. The featured cases illustrate the importance of the surgeon's role in postmarket surveillance of medical devices and reporting device failures to the responsible agencies and manufacturers. PMID:24635137

Woerdeman, Peter A; Cochrane, David D

2014-05-01

358

The Melody(R) valve and Ensemble(R) delivery system for transcatheter pulmonary valve replacement  

PubMed Central

The Melody transcatheter pulmonary valve (TPV) is a percutaneous valve system designed for the treatment of obstruction and/or regurgitation of prosthetic conduits placed between the right ventricle and pulmonary arteries in patients with congenital heart disease. In 2000, Melody TPV became the first transcatheter valve implanted in a human; in 2006 it became the first transcatheter valve commercially available anywhere in the world; and in 2010 it was launched as the first commercially available transcatheter valve in the United States. In this review, we present the clinical background against which the Melody valve was developed and implemented, introduce the rationale for and challenges of transcatheter valve technology for this population, outline the history and technical details of its development and use, and summarize currently available data concerning the performance of the device. PMID:23834411

McElhinney, Doff B; Hennesen, Jill T

2013-01-01

359

Hour-glass deformity of the pulmonary valve: a third type of pulmonary valve stenosis.  

PubMed Central

In the 12 years from 1975 to 1987, 55 patients had open pulmonary valve surgery for isolated congenital stenosis of the pulmonary valve. Three types of pulmonary stenosis were seen: (a) dome-shaped pulmonary stenosis (34 patients); (b) dysplastic pulmonary valves with thick cauliflower-like cusps (12 patients), and (c) hour-glass deformity of the pulmonary valve, with "bottle-shaped" sinuses (nine patients). This third type has not been described before. Preoperative identification of the valve structure is important because the choice of treatment (balloon dilatation for some dome-shaped valves and excision for dysplastic and hour-glass valves) depends on the type of stenosis. Images Fig 2 Fig 3 Fig 4 PMID:3415872

Milo, S; Fiegel, A; Shem-Tov, A; Neufeld, H N; Goor, D A

1988-01-01

360

High precision high flow range control valve  

DOEpatents

A fluid control valve is described having a valve housing having first and second valve housing openings for the ingress and egress of fluid through the control valve. Disposed within a void formed by the control valve is a sleeve having at least one sleeve opening to permit the flow of fluid therethrough. A flow restricter travels within the sleeve to progressively block off the sleeve opening and thereby control flow. A fluid passageway is formed between the first valve housing opening and the outer surface of the sleeve. A second fluid passageway is formed between the inside of the sleeve and the second valve housing opening. Neither fluid passageway contains more than one 90 [degree] turn. In the preferred embodiment only one of the two fluid passageways contains a 90[degree] turn. In another embodiment, the control valve housing is bifurcated by a control surface having control surface opening disposed therethrough. A flow restricter is in slidable contact with the control surface to restrict flow of fluid through the control surface openings. 12 figs.

McCray, J.A.

1999-07-13

361

[Anatomic and functional features of venous valves].  

PubMed

The comparison of the venous system in the human organism, and in particular the venous valves of the lower limbs, with studies conducted in animal models helped us to understand better the mechanisms involved in adapting to the upright position and walking. We examined work conducted in several species from the horse to the dog, especially in animals who often take on an upright position such as the chimpanzee and the kangouroo, in search for structures comparable to those in man. Different types of valves can be described in man: flotting valves (bicuspid, pigeon nest valves); reinforced valves (mid-thigh); reinforcing valves (periarticular zone in the knee); finally, "flat" valves which are highly resistant formations but with little anti-back flow action. We also describe valvular structures with muscle cells found in the plantar aspect of the foot and the veins of the quadriceps muscle, these valves may have an active hematopropulsive action (Bassi). These results allowed us to identify certain common points between the structures observed in the posterior legs of certain animals and to propose models for investigating venous diseases. PMID:9480339

Griton, P; Vanet, P; Cloarec, M

1997-05-01

362

Review: Mechanobiology of the Aortic Heart Valve  

Microsoft Academic Search

The aortic heart valve is a complex and sophisticated structure that functions in a mechanically challeng- ing environment. With each cardiac cycle, blood flow exerts shear stresses, bending stress and tensile and compressive forces on the valve tissue. These forces determine a plethora of biological responses, includ- ing gene expression, protein activation and cell phe- notype. Consequently, mechanical forces may

Jonathan T. Butcher; Craig A. Simmons; James N. Warnock

2008-01-01

363

Perioperative antibiotic prophylaxis and prosthetic valve endocarditis  

Microsoft Academic Search

A study of twenty-five cases of prosthetic valve endocarditis suggests that the antibiotics used for perioperative prophylaxis may alter the type and antibiotic sensitivity of organisms which subsequently infect the artificial valves. Based on the results of this study, the authors have been able to modify their prophylactic regime to encompass these organisms and to predict the antibiotics most likely

C. Ward; A. E. Jephcott; C. A. Hardisty

1977-01-01

364

Smart valves open window to process  

Microsoft Academic Search

Technology is driving the development of smart valve-mounted field devices and emerging fieldbus protocols. These devices will be able to perform advanced functions, which are not possible with traditional analog products. The communicating digital valve controller (DVC) will also store in memory detailed maintenance and identification information. Today`s analog field instrumentation provides very little information to the distributed control system

Grumstrup

1995-01-01

365

Minimizing energy losses in control valves  

SciTech Connect

The pulp and paper industry uses massive amounts of energy, but it could reduce its electricity consumption by about 2,000 MW worldwide by simply optimizing the pumping of process liquids. Wasted pumping power can be significantly reduced by sizing pumps and control valves more accurately, and by using new methods of pump and valve selection. Combining the improved control valve's installed flow characteristic with state-of-the-art sizing and simulation programs ensures minimal pressure drop across the control valve without loss of accurate and reliable control in all process conditions. If accurate process condition information is available at the planning stage, even more significant pumping energy savings can be achieved. Moreover, reduced pressure drop across the control valve reduces the likelihood of valve cavitation. This, in turn, reduces the need for noise attenuation, preventing cavitation erosion, and repairing damage. To make the most of the advantages gained by using highly developed control valve sizing and selection programs, closer cooperation between process licensees, process users, and valve manufacturers is also required.

Niemela, I.; Pyotsia, J. (Neles-Jamesbury Oy, Helsinki (Finland))

1994-08-01

366

Research on fluidics, valves, and proportional amplifiers  

NASA Technical Reports Server (NTRS)

Research and development being conducted at the Systems and Controls Laboratory is reviewed. Static characteristics (supply, input, transfer, output, and noise characteristics) of laminar proportional amplifiers were investigated. Other topics discussed include velocity profiles for laminar fluidic jets, speed control systems employing a jet pipe valve, and power amplification with a vortex valve.

1974-01-01

367

Digital hydraulic valving system. [design and development  

NASA Technical Reports Server (NTRS)

The design and development are reported of a digital hydraulic valving system that would accept direct digital inputs. Topics include: summary of contractual accomplishments, design and function description, valve parameters and calculations, conclusions, and recommendations. The electrical control circuit operating procedure is outlined in an appendix.

1973-01-01

368

Control system for exhaust gas recirculating valve  

Microsoft Academic Search

An exhaust gas recirculation control system for an internal combustion engine is disclosed in which a pressure operated exhaust gas recirculation (EGR) valve governs the flow of engine exhaust gas into the engine intake. The EGR valve is supplied with operating pressure from the engine intake manifold via a pressure amplifier. The amplifier has a pressure input which tends to

Caldwell

1976-01-01

369

High speed exhaust gas recirculation valve  

Microsoft Academic Search

In order to minimize pollutants such as Nox, internal combustion engines typically include an exhaust gas recirculation (EGR) valve that can be used to redirect a portion of exhaust gases to an intake conduit, such as an intake manifold, so that the redirected exhaust gases will be recycled. It is desirable to have an EGR valve with fast-acting capabilities, and

Rod Fensom; David J. Kidder

2005-01-01

370

Force balanced EGR valve with position feedback  

Microsoft Academic Search

An EGR valve is described for an engine comprising: means for mounting the valve to an engine; housing means supported by the mounting means; diaphragm-piston assembly supported by the housing means; a plate supported at its outer periphery by the housing means; the flexible diaphragm having an outer portion supported by the plate; and biasing means supported within the housing

J. E. Cook

1987-01-01

371

Obstructive bioprosthetic mitral valve thrombus: Management options?  

PubMed

Bioprosthetic valve thrombosis is an extremely rare event, therefore, long-term anticoagulation can be avoided. There is limited experience in the diagnosis and treatment of such a situation. We present the case of a patient with a porcine mitral bioprosthesis who presented with acute pulmonary edema, likely secondary to obstructive valve thrombosis. A favorable outcome was observed after conservative anticoagulant treatment. PMID:24887839

Alshehri, Halia Z; Ismail, Magdi; Ibrahim, Mohamed F

2014-10-01

372

Inexpensive tamper proof safety relief valve  

NASA Technical Reports Server (NTRS)

Basic relief valve has added safety relief valve capability that relieves overpressure before failure can occur. It may be installed in inaccesible areas with a high degree of reliability, constructed from a variety of materials, and adapted to the user's specific application.

Frankewich, P. A.

1970-01-01

373

14 CFR 29.1025 - Oil valves.  

...Space 1 2014-01-01 2014-01-01 false Oil valves. 29.1025 Section 29.1025 Aeronautics...STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Oil System 29.1025 Oil valves. (a) Each oil shutoff must meet the...

2014-01-01

374

14 CFR 25.1025 - Oil valves.  

...Space 1 2014-01-01 2014-01-01 false Oil valves. 25.1025 Section 25.1025 Aeronautics...STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Oil System 25.1025 Oil valves. (a) Each oil shutoff must meet the...

2014-01-01

375

Unique mitral valve mass: Think beyond vegetation  

PubMed Central

Osteosarcoma is a rare cardiac malignant tumor. This case of cardiac osteosarcoma presented with atrial fibrillation. Initial echocardiogram demonstrated mitral valve echodensity and mitral valve regurgitation. Surgery and histopathological examination identified the tumor as an osteosarcoma. Tumor grade appeared to be prognostically important in cardiac sarcoma, with poor prognosis in high-grade tumors.

Farhoud, Mahmoud; Bakdash, Husam

2014-01-01

376

Status of motor operated valves aging assessment  

Microsoft Academic Search

Motor operated valves (MOVs) have a long history of operational problems in nuclear power plants. Resolution of MOV problems in the past has tended to focus on symptoms rather than root cause. Although there has been more attention focused recently on identifying root causes, problems with valve operational readiness resulting from aging and service wear still persist. In addition, weaknesses

Eissenberg

1989-01-01

377

Knocking from valve hammer in triplex pumps  

SciTech Connect

This paper investigates valve hammer as opposed to water hammer in triplex pumps, both of which produce knocking under certain distinctly different hydraulic operations. The occurrence of water hammer is reviewed and the development of valve hammer is discussed and documented.

Collier, S.L.

1983-01-01

378

Training for Emergencies Need for some uniformity of training across airlines. Concern is especially about  

E-print Network

Training for Emergencies · Need for some uniformity of training across airlines. Concern is especially about variability in amount of training for emergencies. Not enough training in general for emergencies. · What are the criteria for training for success. · Try a "hypertext" approach to simulator

379

Frailty and aortic valve disease.  

PubMed

Frailty is a common occurrence in elderly persons and is present in approximately half of the patients being screened for transcatheter aortic valve replacement (TAVR) therapy. Accurate assessment of the likelihood of benefit from intervention in the older patient with aortic stenosis is critical with both surgical aortic valve replacement and TAVR now available. Whereas risk algorithms are available that are helpful in predicting outcomes in patients undergoing surgical procedures, measures of frailty are not included in the algorithms. When considering intervention in the elderly patient, the addition of frailty assessment to determine the true risk in this population is essential to determine potential benefit. Gait speed as determined by the 5-m walk test is the most commonly used single test objective measurement of frailty in patients undergoing cardiac surgery and is an independent predictor of mortality and major morbidity. Wider application of this and other objective measures of frailty in the population undergoing TAVR is necessary to determine whether it is predictive in this population also. PMID:23260463

Mack, Michael

2013-03-01

380

Transcatheter aortic valve replacement in elderly patients  

PubMed Central

Aortic stenosis is the most common native valve disease, affecting up to 5% of the elderly population. Surgical aortic valve replacement reduces symptoms and improves survival, and is the definitive therapy in patients with symptomatic severe aortic stenosis. However, despite the good results of classic surgery, risk is markedly increased in elderly patients with co-morbidities. Transcatheter aortic valve replacement (TAVR) allows implantation of a prosthetic heart valve within the diseased native aortic valve without the need for open heart surgery and cardiopulmonary bypass, offering a new therapeutic option to elderly patients considered at high surgical risk or with contraindications to surgery. To date, several multicenter registries and a randomized trial have confirmed the safety and efficacy of TAVR in those patients. In this chapter, we review the background and clinical applications of TAVR in elderly patients. PMID:22916051

Siqueira, Dimytri; Abizaid, Alexandre; Arrais, Magaly; Sousa, J. Eduardo

2012-01-01

381

Risk assessment of drain valve failure in the K-West basin south loadout pit  

SciTech Connect

The drain valve located in the bottom of the K-West Basin South Loadout Pit (SLOP) could provide an additional leak path from the K Basins if the drain valve were damaged during construction, installation, or operation of the cask loading system. For the K-West Basin SLOP the immersion pail support structure (IPSS) has already been installed, but the immersion pail has not been installed in the IPSS. The objective of this analysis is to evaluate the risk of damaging the drain valve during the remaining installation activities or operation of the cask loading system. Valve damage, as used in this analysis, does not necessarily imply large amounts of the water will be released quickly from the basin, rather valve damage implies that the valve's integrity has been compromised. The analysis process is a risk-based uncertainty analysis where best engineering judgement is used to represent each variable in the analysis. The uncertainty associated with each variable is represented by a probability distribution. The uncertainty is propagated through the analysis by Monte Carlo convolution techniques. The corresponding results are developed as a probability distribution and the risk is expressed in terms of the corresponding complementary cumulative distribution function (''risk curve''). The total risk is the area under the ''risk curve''. The risk of potentially dropping a cask into or on the IPSS and damaging the drain valve is approximately 1 x 10{sup -4} to 2 x 10{sup -5} per year. The risk of objects falling behind the IPSS and damaging the valve is 3 x 10{sup -2} to 6 x 10{sup -3} per year. Both risks are expressed as drain value failure frequencies. The risk of objects falling behind the IPSS and damaging the valve can be significantly reduced by an impact limiter and/or installing a gating or plate over the area bounded by the back of the IPSS and the wall of the SLOP. With either of these actions there is a 90 percent confidence that the frequency of drain valve failure would be less than 1 x 10{sup -6} per year.

MORGAN, R.G.

1999-06-23

382

Centrifugo-pneumatic valving utilizing dissolvable films.  

PubMed

In this article we introduce a novel technology that utilizes specialized water dissolvable thin films for valving in centrifugal microfluidic systems. In previous work (William Meathrel and Cathy Moritz, IVD Technologies, 2007), dissolvable films (DFs) have been assembled in laminar flow devices to form efficient sacrificial valves where DFs simply open by direct contact with liquid. Here, we build on the original DF valving scheme to leverage sophisticated, merely rotationally actuated vapour barriers and flow control for enabling comprehensive assay integration with low-complexity instrumentation on "lab-on-a-disc" platforms. The advanced sacrificial valving function is achieved by creating an inverted gas-liquid stack upstream of the DF during priming of the system. At low rotational speeds, a pocket of trapped air prevents a surface-tension stabilized liquid plug from wetting the DF membrane. However, high-speed rotation disrupts the metastable gas/liquid interface to wet the DF and thus opens the valve. By judicious choice of the radial position and geometry of the valve, the burst frequency can be tuned over a wide range of rotational speeds nearly 10 times greater than those attained by common capillary burst valves based on hydrophobic constrictions. The broad range of reproducible burst frequencies of the DF valves bears the potential for full integration and automation of comprehensive, multi-step biochemical assay protocols. In this report we demonstrate DF valving, discuss the biocompatibility of using the films, and show a potential sequential valving system including the on-demand release of on-board stored liquid reagents, fast centrifugal sedimentation and vigorous mixing; thus providing a viable basis for use in lab-on-a-disc platforms for point-of-care diagnostics and other life science applications. PMID:22692574

Gorkin, Robert; Nwankire, Charles E; Gaughran, Jennifer; Zhang, Xin; Donohoe, Gerard G; Rook, Martha; O'Kennedy, Richard; Ducre, Jens

2012-08-21

383

The applications of silicon liquid crystal light valves to optical data processing: A review  

NASA Technical Reports Server (NTRS)

The applications of the photo-activated, the CCD-addressed, and the variable-grating mode liquid crystal light valves (LCLVs) to optical data processing are described. These applications include image correlation, level slicing, spectral analysis and correlation, bi-spectral image division, and matrix-matrix multiplication.

Efron, U.; Soffer, B. H.; Caulfield, H. J.

1984-01-01

384

Evaluation of Two-Way Valves for Resting Level Respiratory Testing.  

National Technical Information Service (NTIS)

Ten two-way respiratory valves were compared for the influence of their dead space and resistance to air flow characteristics on the accuracy of measurement of 8 ventilation variables and oxygen consumption in normal male human subjects under resting cond...

R. H. James, W. C. Asburry

1977-01-01

385

A novel high temporal resolution phase contrast MRI technique for measuring mitral valve flows  

NASA Astrophysics Data System (ADS)

Mitral valve flow imaging is inherently difficult due to valve plane motion and high blood flow velocities, which can range from 200 cm/s to 700 cm/s under regurgitant conditions. As such, insufficient temporal resolution has hampered imaging of mitral valve flows using magnetic resonance imaging (MRI). A novel phase contrast MRI technique, phase contrast using phase train imaging (PCPTI), has been developed to address the high temporal resolution needs for imaging mitral valve flows. The PCPTI sequence provides the highest temporal resolution to-date (6 ms) for measuring in-plane and through-plane flow patterns, with each velocity component acquired in a separate breathhold. Tested on healthy human volunteers, comparison to a conventional retrogated PC-FLASH cine sequence showed reasonable agreement. Results from a more rigorous validation using digital particle image velocimetry technique will be presented. The technique will be demonstrated in vitro using a physiological flow phantom and a St. Jude Medical Masters Series prosthetic valve.

Voorhees, Abram; Bohmann, Katja; McGorty, Kelly Anne; Wei, Timothy; Chen, Qun

2005-11-01

386

Three-dimensional printed trileaflet valve conduits using biological hydrogels and human valve interstitial cells.  

PubMed

Tissue engineering has great potential to provide a functional de novo living valve replacement, capable of integration with host tissue and growth. Among various valve conduit fabrication techniques, three-dimensional (3-D) bioprinting enables deposition of cells and hydrogels into 3-D constructs with anatomical geometry and heterogeneous mechanical properties. Successful translation of this approach, however, is constrained by the dearth of printable and biocompatible hydrogel materials. Furthermore, it is not known how human valve cells respond to these printed environments. In this study, 3-D printable formulations of hybrid hydrogels are developed, based on methacrylated hyaluronic acid (Me-HA) and methacrylated gelatin (Me-Gel), and used to bioprint heart valve conduits containing encapsulated human aortic valvular interstitial cells (HAVIC). Increasing Me-Gel concentration resulted in lower stiffness and higher viscosity, facilitated cell spreading, and better maintained HAVIC fibroblastic phenotype. Bioprinting accuracy was dependent upon the relative concentrations of Me-Gel and Me-HA, but when optimized enabled the fabrication of a trileaflet valve shape accurate to the original design. HAVIC encapsulated within bioprinted heart valves maintained high viability, and remodeled the initial matrix by depositing collagen and glyosaminoglycans. These findings represent the first rational design of bioprinted trileaflet valve hydrogels that regulate encapsulated human VIC behavior. The use of anatomically accurate living valve scaffolds through bioprinting may accelerate understanding of physiological valve cell interactions and progress towards de novo living valve replacements. PMID:24334142

Duan, B; Kapetanovic, E; Hockaday, L A; Butcher, J T

2014-05-01

387

Demonstration of Mitral Valve Prolapse with CT for Planning of Mitral Valve Repair.  

PubMed

Mitral valve prolapse (MVP), the most frequent cause of severe nonischemic mitral regurgitation, often warrants surgical or interventional valve repair. The severity of mitral regurgitation positively correlates with the development of heart failure and death. Even in patients who are asymptomatic, severe mitral regurgitation causes higher rates of death, heart failure, and atrial fibrillation. Repair procedures for mitral regurgitation have progressed to include leaflet repair, chordal transfer, ring or band annuloplasty, and new percutaneous procedures. In planning for mitral valve repair, detection and localization of mitral valve abnormalities are important. The causes of mitral regurgitation include degenerative mitral valve (eg, prolapsed leaflet, myxomatous degeneration, and Barlow disease [excessive degenerated tissues with elongated chordae]). Cardiac computed tomography (CT) is helpful for depicting mitral valve abnormalities. It allows complete visualization of cardiac anatomic features, including the coronary arteries, paravalvular structures, and cardiac wall motion. This review addresses the role of cardiac CT in depicting anatomic features of the mitral valve, provides a practical method for localizing the exact site of MVP, and discusses the CT findings of various causes of mitral regurgitation. The first step in reconstructing CT images for MVP is to select the best cardiac phase for depicting the anatomic features of the mitral valve. Additional views of the mitral valve then show the specific mitral valve abnormality. This article provides technical tips for demonstrating MVP with CT, as well as imaging results for various causes of MVP and intraoperative findings. Online supplemental material is available for this article. RSNA, 2014. PMID:25310416

Koo, Hyun Jung; Yang, Dong Hyun; Oh, Sang Young; Kang, Joon-Won; Kim, Dae-Hee; Song, Jae-Kwan; Lee, Jae Won; Chung, Cheol Hyun; Lim, Tae-Hwan

2014-10-01

388

Trend of motorcycle engine valves in Japan  

SciTech Connect

Production of motorcycles in Japan has greatly decreased after peaking in 1981. However, as a result of an increase in local production, mainly in Asian nations, the production of sets, often called Knock Down (KD) sets, has been increasing. These sets are a shipment of parts that are ready for assembly in the importing country. In this area, motorcycle manufacturers are trying to improve performance and decrease noise and pollution. This report will outline the trends in motorcycle engine valves and the changes that have occurred with respect to valve materials, valve design specifications, and valve manufacturing processes, as experienced by Nittan Valve Co., Ltd. over the past 15 years. Motorcycles are used in various ways. They are used for transportation, sport, leisure, and hobby. Therefore, the forms and specifications of their bodies and engines are quite varied. The production of motorcycles in Japan has sharply decreased from an era of peak production in 1981 and in recent years, has remained low at around 3 million motorcycles per year. As a result, each motorcycle manufacturer has been promoting the local production in each country, and the production of KD sets is rapidly increasing today. The motorcycle and parts manufacturers are working on employing new technologies for anti-pollution measures, improving performance, decreasing noise, and better safety measures. With this in mind, the technological trends of Japanese engine valves being manufactured by Nittan Valve Co., Ltd. will be reported.

Kiriyama, M.; Sasakura, T. [Nittan Valve Co., Ltd., Tokyo (Japan)

1997-12-31

389

A thin film nitinol heart valve.  

PubMed

In order to create a less thrombogenic heart valve with improved longevity, a prosthetic heart valve was developed using thin film nitinol (NiTi). A "butterfly" valve was constructed using a single, elliptical piece of thin film NiTi and a scaffold made from Teflon tubing and NiTi wire. Flow tests and pressure readings across the valve were performed in vitro in a pulsatile flow loop. Bio-corrosion experiments were conducted on untreated and passivated thin film nitinol. To determine the material's in vivo biocompatibility, thin film nitinol was implanted in pigs using stents covered with thin film NiTi. Flow rates and pressure tracings across the valve were comparable to those through a commercially available 19 mm Perimount Edwards tissue valve. No signs of corrosion were present on thin film nitinol samples after immersion in Hank's solution for one month. Finally, organ and tissue samples explanted from four pigs at 2, 3, 4, and 6 weeks after thin film NiTi implantation appeared without disease, and the thin film nitinol itself was without thrombus formation. Although long term testing is still necessary, thin film NiTi may be very well suited for use in artificial heart valves. PMID:16438227

Stepan, Lenka L; Levi, Daniel S; Carman, Gregory P

2005-11-01

390

Pressure compensated flow control valve  

DOEpatents

The invention is an air flow control valve which is capable of maintaining a constant flow at the outlet despite changes in the inlet or outlet pressure. The device consists of a shell assembly with an inlet chamber and outlet chamber separated by a separation plate. The chambers are connected by an orifice. Also located within the inlet chamber is a port controller assembly. The port controller assembly consists of a differential pressure plate and port cap affixed thereon. The cap is able to slide in and out of the orifice separating the inlet and outlet chambers. When the pressure differential is sufficient, the differential pressure plate rises or falls to maintain a constant air flow. Movement of the port controller assembly does not require the use of seals, diaphragms, tight tolerances, bushings, bearings, hinges, guides, or lubricants.

Minteer, Daniel J. (West Richland, WA)

1999-01-01

391

A Novel Implantable Glaucoma Valve Using Ferrofluid  

PubMed Central

Purpose To present a novel design of an implantable glaucoma valve based on ferrofluidic nanoparticles and to compare it with a well-established FDA approved valve. Setting Massachusetts Eye & Ear Infirmary, Boston, USA. Methods A glaucoma valve was designed using soft lithography techniques utilizing a water-immiscible magnetic fluid (ferrofluid) as a pressure-sensitive barrier to aqueous flow. Two rare earth micro magnets were used to calibrate the opening and closing pressure. In-vitro flow measurements were performed to characterize the valve and to compare it to Ahmed glaucoma valve. The reliability and predictability of the new valve was verified by pressure/flow measurements over a period of three months and X-ray diffraction (XRD) analysis over a period of eight weeks. In vivo assessment was performed in three rabbits. Results In the in vitro experiments, the opening and closing pressures of the valve were 10 and 7 mmHg, respectively. The measured flow/pressure response was linearly proportional and reproducible over a period of three months (1.8 l/min at 12 mmHg; 4.3 l/min at 16 mmHg; 7.6 l/min at 21 mmHg). X-ray diffraction analysis did not show oxidization of the ferrofluid when exposed to water or air. Preliminary in vivo results suggest that the valve is biocompatible and can control the intraocular pressure in rabbits. Conclusions The proposed valve utilizes ferrofluid as passive, tunable constriction element to provide highly predictable opening and closing pressures while maintaining ocular tone. The ferrofluid maintained its magnetic properties in the aqueous environment and provided linear flow to pressure response. Our in-vitro tests showed reliable and reproducible results over a study period of three months. Preliminary in-vivo results were very promising and currently more thorough investigation of this device is underway. PMID:23840691

Paschalis, Eleftherios I.; Chodosh, James; Sperling, Ralph A.; Salvador-Culla, Borja; Dohlman, Claes

2013-01-01

392

Water hammer caused by closure of turbine safety spherical valves  

NASA Astrophysics Data System (ADS)

This paper investigates water hammer effects caused by closure of spherical valves against the discharge. During the first phase of modernisation of Peru?ica high-head hydropower plant (HPP), Montenegro, safety spherical valves (inlet turbine valves) have been refurbished on the first two Pelton turbine units. The valve closure is controlled by the valve actuator (hydraulic servomotor). Because the torque acting on the valve body is dependent on flow conditions the valve closing time may vary significantly for different flow velocities (passive valve). For the passive valve the torques acting on the valve body should be considered in the valve model. The valve closing time results from numerical simulation. On the contrary, for the active valve the valve closing time is assumed prior to simulation. The spherical valve boundary condition is incorporated into the method of characteristics (MOC) algorithm. The staggered (diamond) grid in applying the MOC is used in this paper. The passive valve boundary condition is described by the water hammer equations, the valve equation that relates discharge to pressure head drop and the dynamic equation of the valve body motion (torque equation). The active valve boundary condition is described by the first two equations, respectively. Standard quasi-steady friction model is used for estimating friction losses in plant's tunnel and penstocks. Numerical results using both the active and the passive spherical valve models are compared with results of measurements. It has been found that the influence of flow conditions on the spherical valve closing time is minor for the cases considered. Computed and measured results agree reasonably well.

Karadi?, U.; Bergant, A.; Vukoslav?evi?, P.

2010-08-01

393

Effects of cryopreservation and/or decellularization on extracellular matrix of porcine valves.  

PubMed

The objective of this study was to evaluate the morphology of decellularized and/or cryopreserved porcine pulmonary valves, to determine a solution capable of completely remove the cells without damaging the extracellular matrix. Porcine pulmonary valves were incubated for 24 hs in sodium deoxicholate 1% or sodium dodecyl sulfate 0.1 and 0.3%, with or without associated cryopreservation. Evaluation was done with optical microscopy (Hematoxilin-Eosin, Acetic Orcein and Gomori) and with morphometric analysis. The effectiveness of the solutions was variable, but the best results were obtained with the sodium dodecyl sulfate solution 0.1%. PMID:22086591

Wollmann, Luciana Cristina Ferretti de Nazareno; Laurindo, Carlos A H; Costa, Francisco Diniz Affonso da; Moreno, Andra Novais

2011-01-01

394

Training attentional control in older adults  

Microsoft Academic Search

Recent research has demonstrated benefits for older adults from training attentional control using a variable priority strategy, but the construct validity of the training task and the degree to which benefits of training transfer to other contexts are unclear. The goal of this study was to characterize baseline performance on the training task in a sample of 105 healthy older

Anna MacKay-Brandt

2011-01-01

395

Flow control valve for exhaust gas recirculation system  

Microsoft Academic Search

A flow control valve is provided for use in an exhaust gas recirculation system of an internal combustion engine, whereby a constant flow of the recirculating gas may be maintained. The valve comprises a first and second valve chamber separated by a flow orifice, with a valve body for opening and closing of the flow orifice. Exhaust gas entering the

K. Goto; R. Mitsui

1975-01-01

396

Method of Manufacturing Carbon Fiber Reinforced Carbon Composite Valves  

NASA Technical Reports Server (NTRS)

A method for forming a carbon composite valve for internal combustion engines is discussed. The process includes the steps of braiding carbon fiber into a rope thereby forming a cylindrically shaped valve stem portion and continuing to braid said fiber while introducing into the braiding carbon fiber rope a carbon matrix plug having an outer surface in a net shape of a valve head thereby forming a valve head portion. The said carbon matrix plug acting as a mandrel over which said carbon fiber rope is braided, said carbon fiber rope and carbon matrix plug forming a valve head portion suitable for mating with a valve seat; cutting said braided carbon valve stem portion at one end to form a valve tip and cutting said braided carbon fiber after said valve head portion to form a valve face and thus provide a composite valve preform; and densifying said preform by embedding the braided carbon in a matrix of carbon to convert said valve stem portion to a valve stem and said valve head portion to a valve head thereby providing said composite valve.

Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor)

1998-01-01

397

Flatness-Based Feedback Control of an Automotive Solenoid Valve  

Microsoft Academic Search

This brief considers the control of solenoid valve actuators used for gas exchange in internal combustion engines. Although solenoid valves offer performance benefits over traditional camshaft-based valve systems, maintaining low impact velocity is a critical performance requirement. Flatness provides a convenient framework for meeting a number of performance specifications on the valve's end motion. The proposed control design incorporates voltage

Soon K. Chung; Charles Robert Koch; Alan F. Lynch

2007-01-01

398

Whitey SCHe Ball Valves Provide Test Port Isolation  

SciTech Connect

These valves are 1/4-inch ball valves fabricated of 316 stainless steel. Packing is TFE (standard). They are used as normally closed isolation valves for test ports in the SCHe System between the gage root valve and the pressure indicator.

MISKA, C.R.

2000-10-19

399

Air flow control valve for a HVAC module  

Microsoft Academic Search

An air flow control valve assembly is described for directing air flow through air chambers within a HVAC module housing, the valve assembly comprising: a valve for selectively directing air flow through the air chambers of the HVAC housing; support means including a first end secured to the valve and defining a first axis, and a second end to be

1993-01-01

400

Shock-operated valve would automatically protect fluid systems  

NASA Technical Reports Server (NTRS)

Glandless valve shuts down high-pressure fluid systems when severe shock from an explosion or earthquake occurs. The valve uses a pendulum to support the valve closure plug in the open position. When jarred, the valve body is moved relative to the pendulum and the plug support is displaced, allowing the plug to seat and be held by spring pressure.

Branum, L. W.; Wells, G. H.

1966-01-01

401

Clinical experience with a new pressure-adjustable shunt valve  

Microsoft Academic Search

Summary The pressure-adjustable valve system Codman Medos allows valve pressure adjustment in 18 steps between 30 and 200 mm H2O. A series of 90 patients, 15 children and 75 adults, who were shunted with this new programmable valve, is reported. Indication for shunt insertion were various types of hydrocephalus in 79 cases, malfunction of a medium pressure membrane valve shunt

A. Reinprecht; T. Czech; W. Dietrich

1995-01-01

402

Autoionization in gas jet from a pulsed supersonic gas valve  

Microsoft Academic Search

Pulsed gas valves are used in spheromak (and related plasma devices) to provide a brief pulse of high pressure gas to facilitate breakdown. These valves eject approximately 1 Torr-liter of gas in approximately 100 mus or less. Success of spheromak experiments depends critically on gas valve rise time, duration, throughput, and reproducibility. Calibration of pulsed gas valves has been difficult

Paul Bellan

2001-01-01

403

'Speaking valve' aspiration in a laryngectomy patient.  

PubMed

Tracheo-oesophageal speech using a one-way speaking valve is a common mode of speech rehabilitation for laryngectomy patients. Aspiration of this device can cause significant airway obstruction and pose anaesthetic and surgical challenges during its retrieval. In this case report, we describe our management of a patient who had had a laryngectomy who aspirated his speaking valve through his stoma. Emergency retrieval of the valve was performed, during which difficulties were encountered, first in obtaining an adequate seal for pre-oxygenation, and second in maintaining adequate oxygen saturation. We discuss some innovative techniques that could be used to address these issues. PMID:20191798

Rao Kadam, V; Lambert, P; Pant, H; O'Reilly, M

2010-01-01

404

Combined pressure regulator and shutoff valve  

NASA Technical Reports Server (NTRS)

A remotely operable pressure regulator and shutoff valve particularly suited for achieving high resolution and flow control, and positive shutoff is described. The valve is characterized by a spring-loaded ball coaxially aligned with a fluid port to be sealed, a spring-loaded pintle extended through the port into engagement with the ball, for controlling the position, a spring-loaded diaphragm for controlling the position of the pintle, and an axially displaceable spring supported by a movable stop which, in turn, is repositioned by a selectively operable stepper motor. Thus, the pressure-response characteristics for the valve can be varied through a selective repositioning of the stop.

Koch, E. F. (inventor)

1974-01-01

405

Valve Cap For An Electric Storage Cell  

DOEpatents

The valve cap for an electric storage cell includes a central annular valve seat (23) and a membrane (5) fixed by its peripheral edge and urged against the seat by a piston (10) bearing thereagainst by means of a spring (12), the rear end of said spring (12) bearing on the endwall (8) of a chamber (20) formed in the cap and containing the piston (10) and the spring. A vent (19) puts the chamber (20) into communication with the atmosphere. A central orifice (26, 28) through the piston (10) and the membrane (5), enables gas from within the cell to escape via the top vent (19) when the valve opens.

Verhoog, Roelof (Bordeaux, FR); Genton, Alain (Merignac, FR)

2000-04-18

406

Three-dimensional echocardiography in valve disease  

PubMed Central

This review covers the role of three-dimensional (3D) echocardiography in the diagnosis of heart valve disease. Several factors have contributed to the evolution of this technique, which is currently a simple and routine method: rapid evolution in probe and computer technologies, demonstration that 3D data sets allowed more complete and accurate evaluation of cardiac structures, emerging clinical experience indicating the strong potential particularly in valve diseases, volume and function of the two ventricle measurements and several other fields. This report will review current and future applications of 3D echocardiography in mitral, aortic and tricuspid valve diseases underlying both qualitative (morphologic) and quantitative advantages of this technique. PMID:21977273

COLOMBO, CHIARA; TAMBORINI, GLORIA; PEPI, MAURO; ALIMENTO, MARINA; FIORENTINI, CESARE

2007-01-01

407

A complicated case of mitral valve disease.  

PubMed Central

A patient with rheumatic mitral stenosis and previous cerebral embolism had a myocardial infarction during cardiac catheterisation. She later developed severe mitral regurgitation one year after open valvotomy and at valve replacement was found to have a papillary tumour of the mitral valve. Unexplained low cardiac output occurred four days after operation. Postmortem examination showed thrombotic occlusion of the xenograft prosthesis, a complication not previously seen with tissue valves. Both of these rare events were suggested by the patient's clinical course and could have been diagnosed with cross sectional echocardiography. Images PMID:3970791

James, S E; McKay, R; Ross, D N

1985-01-01

408

Current trends in aortic valve replacement: development of the rapid deployment EDWARDS INTUITY valve system.  

PubMed

Although conventional aortic valve replacement (AVR) surgery remains the gold standard for patients with aortic stenosis, transcutaneous aortic valve replacement is becoming increasingly common in high-risk patients. The techniques of minimal invasive surgery (MIS) have been well known for many years, but MIS is applied in a disappointingly low percentage of patients undergoing AVR surgery. The EDWARDS INTUITY rapid deployment aortic valve system is designed to facilitate the performance of MIS AVR surgery. In addition, the reduced implantation times may be beneficial in higher risk patients or those requiring concomitant procedures. The system combines established pericardial valve technology with modern stent expertise obtained from the transcutaneous aortic valve replacement experience. Preliminary results from a multicenter trial have shown low rates of morbidity and mortality, and excellent hemodynamic performance. The EDWARDS INTUITY promises to be an exciting device that may further change the landscape of aortic valve intervention. PMID:23895073

Borger, Michael A; Dohmen, Pascal; Misfeld, Martin; Mohr, Friedrich W

2013-07-01

409

Transvenous valve-in-valve replacement preserving the function of a transvalvular defibrillator lead.  

PubMed

Although feasibility and efficacy of percutaneous tricuspid valve-in-valve implantation have been established, a transtricuspid pacing or defibrillator lead might preclude this technique: lead damage can cause lead dysfunction resulting in inappropriate or inefficient pacing or shocks. In these cases, lead removal is thought to be the only option. We describe a patient who presented with rapid clinical deterioration due to tricuspid valve stenosis early after implantation of an internal defibrillator with a transvalvular shock-lead. A transvenous valve-in-valve implantation of the tricuspid valve was performed after protecting the defibrillator-lead with a custom-made covered stent. We describe the technical issues, the clinical outcome, and the evolution of lead function after implantation. 2014 Wiley Periodicals, Inc. PMID:24677782

De Meester, Pieter; Budts, Werner; Gewillig, Marc

2014-12-01

410

Advanced technology for space shuttle auxiliary propellant valves  

NASA Technical Reports Server (NTRS)

Valves for the gaseous hydrogen/gaseous oxygen shuttle auxiliary propulsion system are required to feature low leakage over a wide temperature range coupled with high cycle life, long term compatibility and minimum maintenance. In addition, those valves used as thruster shutoff valves must feature fast response characteristics to achieve small, repeatable minimum impulse bits. These valve technology problems are solved by developing unique valve components such as sealing closures, guidance devices, and actuation means and by demonstrating two prototype valve concepts. One of the prototype valves is cycled over one million cycles without exceeding a leakage rate of 27 scc's per hour at 450 psia helium inlet pressure throughout the cycling program.

Wichmann, H.

1973-01-01

411

Method for reducing valve loops for improving turbine efficiency  

SciTech Connect

A method is described for reducing valve loops in a partial-arc steam turbine comprising the steps of: computing in the controller the amount of steam flow required to establish a power output of the turbine commensurate with the load demand; determining a first intersection point of a first reduced steam flow valve loop formed by gradual closing of a one of the control valves with a corresponding reduced steam flow caused by gradual closing of the division valve; gradually closing the division valve to reduce steam pressure at the control valves until the first intersection point is reached as indicated by monitored steam flow; fully opening the division valve to return steam pressure to its normal value while simultaneously closing the one of the control valves so that steam flow is maintained at the value of the first intersection point; and gradually closing the one of the control valves in correspondence with the first valve loop until it is fully closed.

Silvestri, G.J. Jr.

1989-04-11

412

Percutaneous Transcatheter Aortic Disc Valve Prosthesis Implantation: A Feasibility Study  

SciTech Connect

Purpose: Over the past 30 years there have been experimental efforts at catheter-based management of aortic valve regurgitation with the idea of extending treatment to nonsurgical candidates. A new catheter-based aortic valve design is described.Methods: The new catheter-delivered valve consists of a stent-based valve cage with locking mechanism and a prosthetic flexible tilting valve disc. The valve cage is delivered first followed by deployment and locking of the disc. In acute experiments, valve implantation was done in four dogs.Results: Valve implantation was successful in all four animals. The implanted valve functioned well for the duration of the experiments (up to 3 hr).Conclusion: The study showed the implantation feasibility and short-term function of the tested catheter-based aortic disc valve. Further experimental studies are warranted.

Sochman, Jan [Department of Cardiology, Institute for Clinical and Experimental Medicine, Videnska 1958/9, 140 21 Prague 4 (Czech Republic); Peregrin, Jan H. [Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Videnska 1958/9, 140 21 Prague 4 (Czech Republic); Pavcnik, Dusan; Timmermans, Hans; Roesch, Josef [Dotter Interventional Institute, Oregon Health Sciences University, 3181 S.W. Jackson Park Road, L342, Portland, Oregon, 97201-3098 (United States)

2000-09-15

413

Effects of sports activity in athletes with bicuspid aortic valve and mild aortic regurgitation  

Microsoft Academic Search

ObjectiveIn this study, the impact of regular training on left ventricle morphology in a group of athletes with bicuspid aortic valve (BAV) was evaluated.DesignLongitudinal cohort study. A group of competitive athletes with BAV was followed up with a yearly standard echocardiographic examination for 5 years.SettingSport Medicine Centre, University of Florence, Pre-Participation Protocol StudyParticipantsA group of 88 consecutive athletes diagnosed with

G. Galanti; L. Stefani; L. Toncelli; M. C. R. Vono; R. Mercuri; N. Maffulli

2010-01-01

414

Design and performance characteristic analysis of servo valve-type water hydraulic poppet valve  

Microsoft Academic Search

For water hydraulic system control, the flow or pressure control using high-speed solenoid valve controlled by PWM control\\u000a method could be a good solution for prevention of internal leakage. However, since the PWM control of on-off valves cause\\u000a extensive flow and pressure fluctuation, it is difficult to control the water hydraulic actuators precisely. In this study,\\u000a the servo valve-type water

Sung-Hwan Park

2009-01-01

415

Method and apparatus for monitoring motor operated valve motor output torque and power at valve seating  

DOEpatents

A method and apparatus are provided for monitoring a motor operated valve during the brief period when the valve seats and the torque switch trips to deenergize the valve motor. The method uses voltage measurements on the load side of a deenergizing switch that opens to deenergize the motor to determine, among other things, final motor rotational speed and the decelerating torque at motor deenergization.

Casada, Donald A. (Oak Ridge, TN)

1996-01-01

416

Risk assessment of K Basin twelve-inch and four-inch drain valve failure from a postulated seismic initiating event  

SciTech Connect

The Spent Nuclear Fuel (SNF) Project will transfer metallic SNF from the Hanford 105 K-East and 105 K-West Basins to safe interim storage in the Canister Storage Building in the 200 Area. The initial basis for design, fabrication, installation, and operation of the fuel removal systems was that the basin leak rate which could result from a postulated accident condition would not be excessive relative to reasonable recovery operations. However, an additional potential K Basin water leak path is through the K Basin drain valves. Three twelve-inch drain valves are located in the main basin bays along the north wall. Five four-inch drain valves are located in the north and south loadout pits (NLOP and SLOP), the weasel pit, the technical viewing pit, and the discharge chute pit. The sumps containing the valves are filled with concrete which covers the drain valve body. Visual observations indicate that only the valve's bonnet and stem are exposed above the basin concrete floor for the twelve-inch drain valve and that much less of the valve's bonnet and stem are exposed above the basin concrete floor for the five four-inch drain valves. It was recognized, however, that damage of the drain valve bonnet or stem during a seismic initiating event could provide a potential K Basin water leak path. The objectives of this analysis are to: (1) evaluate the likelihood of damaging the three twelve-inch drain valves located along the north wall of the main basin and the five four-inch drain valves located in the pits from a seismic initiating event, and (2) determine the likelihood of exceeding a specific consequence (initial leak rate) from a damaged valve. The analysis process is a risk-based uncertainty analysis where each variable is modeled using available information and engineering judgement. The uncertainty associated with each variable is represented by a probability distribution (probability density function). Uncertainty exists because of the inherent randomness associated with the distribution of values that a variable may assume, and because of a lack of knowledge concerning a variable. Engineering judgement and technical information are used to develop the variable probability density functions, but the bounds of the probability density function are based on physical limitations. The uncertainty, described by probability distributions, is propagated through the analysis by Monte Carlo convolution techniques. The corresponding results are developed as a probability distribution and expressed in terms of the corresponding complementary cumulative distribution function (''risk curve'').

MORGAN, R.G.

1999-06-23

417

Effect of preoperative oral sildenafil on severe pulmonary artery hypertension in patients undergoing mitral valve replacement  

PubMed Central

Aim: Long standing mitral valve disease is usually associated with severe pulmonary hypertension. Perioperative pulmonary hypertension is a risk factor for right ventricular (RV) failure and a cause for morbidity and mortality in patients undergoing mitral valve replacement. Phosphodiesterase 5 inhibitor-sildenafil citrate is widely used to treat primary pulmonary hypertension. There is a lack of evidence of effects of oral sildenafil on secondary pulmonary hypertension due to mitral valve disease. The study aims to assess the effectiveness of preoperative oral sildenafil on severe pulmonary hypertension and incidence of RV failure in patients undergoing mitral valve replacement surgery. Materials and Methods: A total of 40 patients scheduled for mitral valve replacement with severe pulmonary hypertension (RV systolic pressure (RVSP) ?60 mmHg) on preoperative transthoracic echo were randomly treated with oral sildenafil 25 mg (N = 20) or placebo (N = 20) eight hourly for 24 h before surgery. Hemodynamic variables were measured 20 min after insertion of pulmonary artery catheter (PAC) under anesthesia (T1), 20 min at weaning from cardiopulmonary bypass (CPB) (T2) and after 1,2, and 6 h (T3, T4, T5, respectively) during the postoperative period. Results: Systolic and mean pulmonary artery pressure (MPAP) and pulmonary vascular resistance index (PVRI) were significantly lower (P < 0.0001) in sildenafil group at all times. Ventilation time and postoperative recovery room stay were significantly lower (P < 0.001) in sildenafil group. Conclusion: Sildenafil produces significant pulmonary vasodilatory effect as compared with placebo in mitral valve replacement patients with severe pulmonary hypertension. It also reduces ventilation time and intensive care unit (ICU) stay time as compared with placebo. It is concluded that sildenafil is effective in reducing pulmonary hypertension when administered preoperatively in patients with severe pulmonary hypertension undergoing mitral valve replacement surgery. PMID:24987174

Gandhi, Hemang; Shah, Bipin; Patel, Ramesh; Toshani, Rajesh; Pujara, Jigisha; Kothari, Jignesh; Shastri, Naman

2014-01-01

418

In vitro susceptibility of high virulence microorganisms isolated in heart valve banking.  

PubMed

Storage preparation of human heart valves for implants generally includes incubation in an antimicrobial disinfection solution and cryopreservation. Changes in patterns of microorganisms susceptibility to antibiotics is a variable process of that promote its inefficiency. The aim of this study has been an evaluation of in vitro susceptibility of high virulence microorganisms isolated in our tissue bank for 14 years in order to evaluate the efficiency, and to promote changes for further antibiotics mixtures as well. Data presented in this study show that microorganisms isolates in valve banking display susceptibility patterns similar to those shown in other clinical circumstances, and the most commonly used antibiotics regimes are useful to date. An antibiotic cocktail containing aminoglicoside in addition to ciprofloxacin and vancomycin is an efficient mixture to be used in valve banking. Further studies will be necessary for monitoring patterns changes of in vitro susceptibility of microbiological isolates in tissue banking. PMID:22618487

Villalba, R; Solis, F; Forns, G; Jimenez, A; Eisman, M; Gonzlez, Ana I; Linares, M J; Casal, M; Gmez Villagrn, J L

2012-08-01

419

The safety valve and climate policy  

E-print Network

In discussions of a cap-and-trade system for implementation of Kyoto Protocol-type quantity targets, a "safety valve" was proposed where, by government sales of emissions permits at a fixed price, the marginal cost of the ...

Jacoby, Henry D.; Ellerman, A. Denny.

420

How Is Heart Valve Disease Treated?  

MedlinePLUS

... page from the NHLBI on Twitter. How Is Heart Valve Disease Treated? Currently, no medicines can cure ... Treating, or Relieving the Symptoms of Other Related Heart Conditions To relieve the symptoms of heart conditions ...

421

Glovebox pressure relief and check valve  

SciTech Connect

This device is a combined pressure relief valve and check valve providing overpressure protection and preventing back flow into an inert atmosphere enclosure. The pressure relief is embodied by a submerged vent line in a mercury reservior, the releif pressure being a function of the submerged depth. The pressure relief can be vented into an exhaust system and the relieving pressure is only slightly influenced by the varying pressure in the exhaust system. The check valve is embodied by a ball which floats on the mercury column and contacts a seat whenever vacuum exists within the glovebox enclosure. Alternatively, the check valve is embodied by a vertical column of mercury, the maximum back pressure being a function of the height of the column of mercury.

Blaedel, K.L.

1986-03-17

422

Valve, normally open, titanium: Pyronetics Model 1425  

NASA Technical Reports Server (NTRS)

An operating test series was applied to two explosive actuated, normally open, titanium valves. There were no failures. Tests included: proof pressure and external leakage test, gross leak test, post actuation leakage test, and burst pressure test.

Avalos, E.

1972-01-01

423

Exhaust gas recirculation valve malfunction indicator apparatus  

Microsoft Academic Search

An internal combustion engine is provided with an exhaust gas recirculating (EGR) system containing a vacuum\\/electric switch assembly activated in response to a non-movement type malfunction of the EGR valve to energize a warning light.

1977-01-01

424

High-Performance Valve Promises Safe Relief  

NASA Technical Reports Server (NTRS)

Using an improved valve design developed under an SBIR contract with Stennis Space Center, Marotta Scientific's PRV95 provides stability over the entire operational range, from fully closed to fully open. The valve employs a concept known as upstream control for valve positioning, making it more dependable with excellent repeatability and minimal lag time. The PRV95 design is unique in its ability to maintain a seal near the set point of the relief limit. Typically, relief valves seal tightly up to 90 percent set point and then reseat when pressure is reduced to 85 percent of set point. This new technology maintains seal integrity until 98 percent of set point and will reseat at 95 to 97 percent of set point. This allows the operator to protect a system without exceeding its limits.

2002-01-01

425

Large scale steam valve test: Performance testing of large butterfly valves and full scale high flowrate steam testing  

SciTech Connect

This report presents the results of the design testing of large (36-inch diameter) butterfly valves under high flow conditions. The two butterfly valves were pneumatically operated air-open, air-shut valves (termed valves 1 and 2). These butterfly valves were redesigned to improve their ability to function under high flow conditions. Concern was raised regarding the ability of the butterfly valves to function as required with high flow-induced torque imposed on the valve discs during high steam flow conditions. High flow testing was required to address the flow-induced torque concerns. The valve testing was done using a heavily instrumented piping system. This test program was called the Large Scale Steam Valve Test (LSSVT). The LSSVT program demonstrated that the redesigned valves operated satisfactorily under high flow conditions.

Meadows, J.B.; Robbins, G.E.; Roselius, D.G. [and others

1995-05-01

426

Flow-induced vibration of a steam control valve  

NASA Astrophysics Data System (ADS)

Main steam control valves in power plants are required to operate underwide ranges of valve openings and pressure ratios. In the present paper, experimental and numerical investigations are conducted using rigid and flexible valve head supports to clarify the mechanisms of valve head vibrations that are caused by unsteady flows around the valve. The results obtained using the rigid support without valve head vibration show that the unsteady flow around the valve head causes pressure fluctuations on the valve head surface with random and impulsive wave forms. When using the flexible support, the valve head vibrates near the natural frequency of the valve head support system, and vibrations are excited around the operating conditions where the pressure fluctuation becomes greater when using the rigidly supported valve head. When the valve head vibration increases, the pressure fluctuation becomes periodic with the same frequency as the valve head vibration. The numerical results show that the response of the separated jet lags behind the valve head motion. As a result, the lateral fluid force adds negative damping on the vibration on the valve head.

Yonezawa, Koichi; Ogawa, Ryohei; Ogi, Kanako; Takino, Tomofumi; Tsujimoto, Yoshinobu; Endo, Takahide; Tezuka, Kenichi; Morita, Ryo; Inada, Fumio

2012-11-01

427

Mitral valve lipomatous hamartoma: a rare entity.  

PubMed

Lipomatous hamartoma of cardiac valves is a very rare entity, with only three reported cases in children. We describe the case of a 9-year-old girl with a mass in the mitral valve, which was detected in an echocardiogram performed for heart murmur investigation. At surgery, a white round-shaped tumour was removed and histopathological examination revealed a lipomatous hamartoma. PMID:24044592

Francisco, Andreia; Gouveia, Rosa; Anjos, Rui

2014-10-01

428

Computational Modeling of Aortic Heart Valves  

Microsoft Academic Search

\\u000a Computational modeling is an excellent tool with which to investigate the mechanics of the aortic heart valve. The setting\\u000a of the heart valve presents complex dynamics and mechanical behavior in which solid structures interact with a fluid domain.\\u000a There currently exists no standard approach, a variety of strategies have been used to address the different aspects of modeling\\u000a the heart

Laura R. Croft; Mohammad R. Kaazempur Mofrad

429

Mitral valve repair in heart failure  

Microsoft Academic Search

Mitral regurgitation MR is a frequent complication of end-stage heart failure. Historically, these patients were either managed medically or with mitral valve replacement, both associated with poor outcomes. Mitral valve repair via an 'undersized' annuloplasty repair is safe and effectively corrects MR in heart-failure patients. All of the observed changes contribute to reverse remodeling and restoration of the normal left-ventricular

Iva A. Smolens; Francis D. Pagani; Steven F. BollingU

2000-01-01

430

Native valve Escherichia coli endocarditis following urosepsis  

PubMed Central

Gram-negative organisms are a rare cause of infective endocarditis. Escherichia coli, the most common cause of urinary tract infection and gram-negative septicemia involves endocardium rarely. In this case report, we describe infection of native mitral valve by E. coli following septicemia of urinary tract origin in a diabetic male; subsequently, he required prosthetic tissue valve replacement indicated by persistent sepsis and congestive cardiac failure. PMID:23814428

Rangarajan, D.; Ramakrishnan, S.; Patro, K. C.; Devaraj, S.; Krishnamurthy, V.; Kothari, Y.; Satyaki, N.

2013-01-01

431

Detecting solenoid valve deterioration in in-use electronic diesel fuel injection control systems.  

PubMed

The diesel engine is the main power source for most agricultural vehicles. The control of diesel engine emissions is an important global issue. Fuel injection control systems directly affect fuel efficiency and emissions of diesel engines. Deterioration faults, such as rack deformation, solenoid valve failure, and rack-travel sensor malfunction, are possibly in the fuel injection module of electronic diesel control (EDC) systems. Among these faults, solenoid valve failure is most likely to occur for in-use diesel engines. According to the previous studies, this failure is a result of the wear of the plunger and sleeve, based on a long period of usage, lubricant degradation, or engine overheating. Due to the difficulty in identifying solenoid valve deterioration, this study focuses on developing a sensor identification algorithm that can clearly classify the usability of the solenoid valve, without disassembling the fuel pump of an EDC system for in-use agricultural vehicles. A diagnostic algorithm is proposed, including a feedback controller, a parameter identifier, a linear variable differential transformer (LVDT) sensor, and a neural network classifier. Experimental results show that the proposed algorithm can accurately identify the usability of solenoid valves. PMID:22163597

Tsai, Hsun-Heng; Tseng, Chyuan-Yow

2010-01-01

432

Study on Decellularized Porcine Aortic Valve\\/Poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) Hybrid Heart Valve in Sheep Model  

Microsoft Academic Search

To overcome shortcomings of current heart valve prostheses, novel hybrid valves were fabricated from decellularized porcine aortic valves coated with poly (3-hydroxybutyrate-co-3-hydroxyhexanoate (PHBHHx)). In the mechanical test in vitro, the biomechanical perfor- mance of hybrid valve was investigated. In an in vivo study, hybrid valve conduits were implanted in pulmonary posi- tion in sheep without cardiopulmonary bypass. Uncoated grafts were

Song Wu; Ying-Long Liu; Bin Cui; Xiang-Hua Qu; Guo-Qiang Chen

2007-01-01

433

MEMS Micro-Valve for Space Applications  

NASA Technical Reports Server (NTRS)

We report on the development of a Micro-ElectroMechanical Systems (MEMS) valve that is designed to meet the rigorous performance requirements for a variety of space applications, such as micropropulsion, in-situ chemical analysis of other planets, or micro-fluidics experiments in micro-gravity. These systems often require very small yet reliable silicon valves with extremely low leak rates and long shelf lives. Also, they must survive the perils of space travel, which include unstoppable radiation, monumental shock and vibration forces, as well as extreme variations in temperature. Currently, no commercial MEMS valve meets these requirements. We at JPL are developing a piezoelectric MEMS valve that attempts to address the unique problem of space. We begin with proven configurations that may seem familiar. However, we have implemented some major design innovations that should produce a superior valve. The JPL micro-valve is expected to have an extremely low leak rate, limited susceptibility to particulates, vibration or radiation, as well as a wide operational temperature range.

Chakraborty, I.; Tang, W. C.; Bame, D. P.; Tang, T. K.

1998-01-01

434

Split Venturi, Axially-Rotated Valve  

DOEpatents

The present invention provides an axially-rotated valve which permits increased flow rates and lower pressure drop (characterized by a lower loss coefficient) by using an axial eccentric split venturi with two portions where at least one portion is rotatable with respect to the other portion. The axially-rotated valve typically may be designed to avoid flow separation and/or cavitation at full flow under a variety of conditions. Similarly, the valve is designed, in some embodiments, to produce streamlined flow within the valve. A typical cross section of the eccentric split venturi may be non-axisymmetric such as a semicircular cross section which may assist in both throttling capabilities and in maximum flow capacity using the design of the present invention. Such a design can include applications for freeze resistant axially-rotated valves and may be fully-opened and fully-closed in one-half of a complete rotation. An internal wide radius elbow typically connected to a rotatable portion of the eccentric venturi may assist in directing flow with lower friction losses. A valve actuator may actuate in an axial manner yet be uniquely located outside of the axial flow path to further reduce friction losses. A seal may be used between the two portions that may include a peripheral and diametrical seal in the same plane.

Walrath, David E. (Laramie, WY); Lindberg, William R. (Laramie, WY); Burgess, Robert K. (Sheridan, WY)

2000-08-29

435

Flow Split Venturi, Axially-Rotated Valve  

DOEpatents

The present invention provides an axially-rotated valve which permits increased flow rates and lower pressure drop (characterized by a lower loss coefficient) by using an axial eccentric split venturi with two portions where at least one portion is rotatable with respect to the other portion. The axially-rotated valve typically may be designed to avoid flow separation and/or cavitation at full flow under a variety of conditions. Similarly, the valve is designed, in some embodiments, to produce streamlined flow within the valve. An axially aligned outlet may also increase the flow efficiency. A typical cross section of the eccentric split venturi may be non-axisymmetric such as a semicircular cross section which may assist in both throttling capabilities and in maximum flow capacity using the design of the present invention. Such a design can include applications for freeze resistant axially-rotated valves and may be fully-opened and fully-closed in one-half of a complete rotation. An internal wide radius elbow typically connected to a rotatable portion of the eccentric venturi may assist in directing flow with lower friction losses. A valve actuator may actuate in an axial manner yet be uniquely located outside of the axial flow path to further reduce friction losses. A seal may be used between the two portions that may include a peripheral and diametrical seal in the same plane. A seal separator may increase the useful life of the seal between the fixed and rotatable portions.

Walrath, David E. (Laramie, WY); Lindberg, William R. (Laramie, WY); Burgess, Robert K. (Sheridan, WY); LaBelle, James (Murrieta, CA)

2000-02-22

436

Recent improvements in check valve monitoring methods  

SciTech Connect

In support of the NRC Nuclear Plant Aging Research (NPAR) program, ORNL has carried out an evaluation of three check valve monitoring methods: acoustic emission, ultrasonic inspection, and magnetic flux signature analysis (MFSA). This work has focused on determining the capabilities of each method to provide diagnostic information useful in determining check valve aging and service wear effects (degradation) and undesirable operating modes. In addition, as part of the ORNL Advanced Diagnostic Engineering Research and Development Center (ADEC), two noval nonintrusive monitoring methods were developed (external ac- and dc-magnetic monitoring) that provide several improvements over the other methods. None of the examined methods could, by themselves, monitor the instantaneous position and motion of check valve internals and valve leakage; however, the combination of acoustic emission monitoring with one of the other methods provides the means to determine vital check valve operational information. This paper describes the benefits and limitations associated with each method and includes recent laboratory and field test data to illustrate the capabilities of these methods to detect simulated check valve degradation. 3 refs., 22 figs., 4 tabs.

Haynes, H.D.

1990-01-01

437

A simplified model for mitral valve dynamics.  

PubMed

Located between the left atrium and the left ventricle, the mitral valve controls flow between these two cardiac chambers. Mitral valve dysfunction is a major cause of cardiac dysfunction and its dynamics are little known. A simple non-linear rotational spring model is developed and implemented to capture the dynamics of the mitral valve. A measured pressure difference curve was used as the input into the model, which represents an applied torque to the anatomical valve chords. A range of mechanical model hysteresis states were investigated to find a model that best matches reported animal data of chord movement during a heartbeat. The study is limited by the use of one dataset found in the literature due to the highly invasive nature of getting this data. However, results clearly highlight fundamental physiological issues, such as the damping and chord stiffness changing within one cardiac cycle, that would be directly represented in any mitral valve model and affect behaviour in dysfunction. Very good correlation was achieved between modeled and experimental valve angle with 1-10% absolute error in the best case, indicating good promise for future simulation of cardiac valvular dysfunction, such as mitral regurgitation or stenosis. In particular, the model provides a pathway to capturing these dysfunctions in terms of modeled stiffness or elastance that can be directly related to anatomical, structural defects and dysfunction. PMID:22119761

Moorhead, K T; Paeme, S; Chase, J G; Kolh, P; Pierard, L; Hann, C E; Dauby, P C; Desaive, T

2013-02-01

438

Police Training.  

ERIC Educational Resources Information Center

The third and fourth annual reports on law enforcement training in New Jersey ("Police Training: The Key to Professional Police Service," 1964-65 and 1965-66) review the powers, responsibilities, and duties of the Police Training Commission; law enforcement officers trained (including failures and total enrollments); hours of programed and other

New Jersey State Dept. of Law and Public Safety, Trenton.

439

Rockwell Coal Lock Hopper Valve: METC SOA Test Valve No. A-16. State-of-the-art Lock Hopper Valve Testing and Development Project. Summary test report  

SciTech Connect

The Rockwell Lock Hopper Valve, METC Test Valve No. A-16, has accumulated over 1000 operating cycles in the Valve Static Test Unit and over 8500 operating cycles in the Valve Dynamic Test Unit. Valve performance with a test media of coarse (less than 1/4 inch but 90 percent retained on 16 mesh) limestone, indicates good potential for solids handling lock hopper service. Operating problems were encountered with fine, caking limestone. Some sealing problems, requiring opening and reclosing the valve, and the seat damage observed show that improvements are needed in the seat design and/or seat purge system. The valve's maintainability was demonstrated by removing the body seat and the disk and refacing them. Valve performance after rework was comparable to initial performance.

Gardner, J.R.; Hall, R.C.; Hornbeck, R.G.; Griffith, R.A.; Galvin, W.E.; Gayheart, T.R.; Maxfield, D.A.

1980-07-01

440

Matter Over Mind: A Randomised-Controlled Trial of Single-Session Biofeedback Training on Performance Anxiety and Heart Rate Variability in Musicians  

PubMed Central

Background Musical performance is a skilled activity performed under intense pressure, thus is often a profound source of anxiety. In other contexts, anxiety and its concomitant symptoms of sympathetic nervous system arousal have been successfully ameliorated with HRV biofeedback (HRV BF), a technique involving slow breathing which augments autonomic and emotional regulatory capacity. Objective: This randomised-controlled study explored the impact of a single 30-minute session of HRV BF on anxiety in response to a highly stressful music performance. Methods A total of 46 trained musicians participated in this study and were randomly allocated to a slow breathing with or without biofeedback or no-treatment control group. A 3 Group2 Time mixed experimental design was employed to compare the effect of group before and after intervention on performance anxiety (STAI-S) and frequency domain measures of HRV. Results Slow breathing groups (n?=?30) showed significantly greater improvements in high frequency (HF) and LF/HF ratio measures of HRV relative to control (n?=?15) during 5 minute recordings of performance anticipation following the intervention (effect size: ?2?=?0.122 and ?2?=?0.116, respectively). The addition of biofeedback to a slow breathing protocol did not produce differential results. While intervention groups did not exhibit an overall reduction in self-reported anxiety, participants with high baseline anxiety who received the intervention (n?=?15) displayed greater reductions in self-reported state anxiety relative to those in the control condition (n?=?7) (r?=?0.379). Conclusions These findings indicate that a single session of slow breathing, regardless of biofeedback, is sufficient for controlling physiological arousal in anticipation of psychosocial stress associated with music performance and that slow breathing is particularly helpful for musicians with high levels of anxiety. Future research is needed to further examine the effects of HRV BF as a low-cost, non-pharmacological treatment for music performance anxiety. PMID:23056361

Wells, Ruth; Outhred, Tim; Heathers, James A. J.; Quintana, Daniel S.; Kemp, Andrew H.

2012-01-01

441

Subsea production test valve assembly  

SciTech Connect

In the subsea test assembly securable within a blowout preventer stack above a subterranean well and positionable between upper and lower portions of a tubular conduit in fluid communication with a production zone within the well, the test assembly is described including an upper subassembly carriable with the upper conduit portion, a lower subassembly carriable with the lower conduit portion, and valve means in the lower subassembly manipulatable between opened and closed positions to control fluid flow within the conduit. The improvement comprises: the upper subassembly including an upper housing and first rigid dog means fixedly secured to the upper housing; the lower subassembly including a lower housing and second rigid dog means fixedly secured to the lower housing; the first rigid dog means positionable between a latch position for latching the upper and lower subassemblies and an unlatch position for unlatching the upper and lower subassemblies upon rotational movement of the first dog means with respect to the second dog means; and lock means axially movable relative to the first and second dog means from a lock position for limiting rotational movement of the first dog means with respect to the second dog means to an unlock position for allowing the first dog means to rotate relative to the second dog means and unlatch the upper subassembly from the lower subassembly.

Yates, P.D.

1988-03-22

442

Advanced microbial check valve development  

NASA Technical Reports Server (NTRS)

A flight certified assembly identified as a Microbial Check Valve (MCV) was developed and tested. The MCV is a canister packed with an iodinated anionic exchange resin. The device is used to destroy organisms in a water stream as the water passes through the device. The device is equally effective for fluid flow in either direction and its primary method of organism removal is killing rather than filtering. The MCV was successfully developed for the space shuttle to: disinfect fuel cell water; and prevent back contamination of the stored potable water supply. One version of the device consists of a high residual iodinated resin bed that imparts approximately 2 ppm of iodine to the fuel cell water as it flows to the potable water tanks. A second version of the device consists of a low residual iodinated resin bed. One of these low residual beds is located at each use port in the potable water system for the dual purpose of removing some iodine from the potable water as it is dispensed and also to prevent back contamination of the potable supply.

Colombo, G. V.; Greenley, D. R.

1980-01-01

443

Tricuspidisation of the aortic valve with creation of a crown-like annulus is able to restore a normal valve function in bicuspid aortic valves  

Microsoft Academic Search

Objective: To evaluate the early results of a new method to repair malfunctioning bicuspid aortic valves by creating a tricuspid valve with a crown-like (i.e. anatomic) annulus. Material and methods: Twelve patients (ages from 10 to 27 years) with chronic regurgitation (and flow-dependent stenosis) of a bicuspid aortic valve underwent repair with the principle of creating a tricuspid valve and

Ren Prtre; Alexander Kadner; Hitendu Dave; Dominique Bettex; Michele Genoni

2006-01-01

444

Diffusion bonding resistant valve development for sodium service  

SciTech Connect

Unanticipated functional failures occurred in valves undergoing containment integrity testing for liquid sodium service. The failures resulted from diffusion bonding of the Stellite 6B valve plug to the Type 316 stainless steel (SS) seat. As a result of these failures, a valve development program was undertaken. A modified valve incorporating a Tribaloy 800 plug showed significant improvement in resistance to diffusion bonding but still failed after long term exposure in a closed position. A second modified valve using Tribaloy 800 in both the valve plug and seat successfully resisted diffusion bonding failure. This paper reports the details of the testing and posttest valve examinations. The results of scanning electron microscopy, dispersive x-ray spectrometry, and metallography provide the characteristics of the valve failures. Limitations of the various valve designs are also discussed.

Crandall, D.L.; Low, J.O.; Chung, D.T.; Loop, R.B.

1984-04-16

445

EGR valve device of internal combustion engines of automobiles  

SciTech Connect

An EGR valve device is described for internal combustion engines of automobiles, consisting of: a valve body; a valve rod slidably borne on the valve body and having, at one end, a valve member capable of opening and closing an exhaust gas recirculation path and being urged to close the valve; a sector-shaped member rotatably supported on the valve body and operatively coupled to the valve rod and having a gear portion; and a driving motor secured to the valve body in such a way that its rotary member shaft intersects a plane containing the sector-shaped member at right angles, and having a pinion secured to the rotary member shaft and meshed with the gear portion of the sector-shaped member.

Makino, H.; Sasaki, A.

1987-09-01

446

Analyses Of Transient Events In Complex Valve and Feed Systems  

NASA Technical Reports Server (NTRS)

Valve systems in rocket propulsion systems and testing facilities are constantly subject to dynamic events resulting from the timing of valve motion leading to unsteady fluctuations in pressure and mass flow. Such events can also be accompanied by cavitation, resonance, system vibration leading to catastrophic failure. High-fidelity dynamic computational simulations of valve operation can yield important information of valve response to varying flow conditions. Prediction of transient behavior related to valve motion can serve as guidelines for valve scheduling, which is of crucial importance in engine operation and testing. In this paper, we present simulations of the diverse unsteady phenomena related to valve and feed systems that include valve stall, valve timing studies as well as cavitation instabilities in components utilized in the test loop.

Ahuja, Vineet; Hosangadi, Ashvin; Cavallo, Peter; Daines, Russell

2005-01-01

447

Pathology Of Explanted Cryopreserved Allograft Heart Valves: Comparison With Aortic Valves From Orthotopic Heart Transplants  

Microsoft Academic Search

Objective: We sought to determine the morphology, mechanisms of deterioration, cellular viability, extracellular matrix integrity, and the role of immune responses in the dysfunction of cryopreserved aortic and pulmonic valve allografts. Methods: We studied 33 explanted left-sided ( n= 20) or right-sided (n= 13) cryopreserved human allograft heart valves explanted several hours to 9 years after operation, 14 nonimplanted allografts,

Richard N. Mitchell; Richard A. Jonas; Frederick J. Schoen

1998-01-01

448

Valve-sparing operation for aortic root aneurysm in patients with bicuspid aortic valve  

Microsoft Academic Search

A ortic root aneurysms are not rare in patients with bicuspid aortic valve, but valve-sparing operations to treat them remain challenging. We describe our surgical method of reconstructing only two commissures, which is extremely simple and easy to reproduce without aortic stenosis.

Yoshihiro Suematsu; Tetsuro Morota; Hiroshi Kubota; Mikio Ninomiya; Shinichi Takamoto

2002-01-01

449

Experiences with simulation of reciprocating compressor valve dynamics  

SciTech Connect

Experience with compressor valve modelling has shown that reciprocating compressor performance can sometimes be improved by subtle changes in valve design. Modelling has led to a better understanding of the physical behavior of valves and of the compression process. Three compressor valve studies presented here demonstrate the benefits of valve modelling. Case 1 challenges the commonly held assumption that reducing the lift of a compressor valve will reduce the efficiency of the compressor. The capacity of this compressor is increased by reducing the valve lift. A plot of BHP/MMSCFD versus valve lift shows an inflection point that assists the analyst in optimizing the design. Case 1 also presents a method of calculating the economic effect of improvements in valve performance. Case 2 demonstrates the effect of inadequate flow area through the valve. Pressure in the clearance volume cannot decrease fast enough if flow areas are inadequate; the result is late valve closure, and therefore decreased valve life. Case 3 shows the importance of considering the design of the cylinder casting in addition to that of the valves. Here, insufficient cylinder flow area constricted gas flow. Since these cases were simulated, the analyst had the opportunity to evaluate the proposed solution over the entire range of operating conditions. He was able to select a valve which solved the immediate problem and be confident that it would perform adequately throughout the specified range of conditions.

Howes, B.; Lin, L.; Zacharias, V. [Beta Machinery Analysis Ltd., Calgary, Alberta (Canada)

1996-12-31

450

Nonlinear control of valves in diesel engines using the derivative-free nonlinear Kalman Filter  

NASA Astrophysics Data System (ADS)

The paper studies robust nonlinear control for gas exchange valves in diesel engines, with the use of the Derivative-free nonlinear Kalman Filter. Robust control of gas exchange valves is important for improving the efficiency in the operation of diesel engines. By applying differential flatness theory the initial nonlinear model of the system is transformed in the linear canonical (Brunovsky) form. For the latter model it is possible to design a state feedback controller that enables accurate tracking of the valve's reference set-points. To estimate the nonmeasurable state variables of the model and the unknown external disturbances the Derivative-free nonlinear Kalman Filter is used as a disturbance observer. The Derivative-free nonlinear Kalman Filter consists of the standard Kalman Filter recursion on the linearized equivalent model of the valve and of computation of state and disturbance estimates using the diffeomorphism (relations about state variables transformation) provided by differential flatness theory. Evaluation tests are performed for assessing the performance of the proposed control scheme.

Rigatos, Gerasimos; Siano, Pierluigi; Arsie, Ivan

2014-10-01

451

EV-13 Helium Valve Discharge Coefficient Characterization by Continuous Water Flow Test  

NASA Astrophysics Data System (ADS)

In this project, the students of the Suborbital Center of Excellence characterized the discharge coefficient of a modified NASA scientific Balloon valve using a water channel that was designed and built by the students specifically to test this valve. This coefficient is used in the balloon flight models (SINBAD) to predict the helium discharge rates at various altitudes and appropriate helium vent durations. Previous phases of the project subjected the valve to both highly transient and steady air flows resulting in a relatively small range of possible discharge coeffi- cient values that compared well to previous tests of the EV-13 valve. In this test, water is to be used as the working fluid because there will be fewer variables in the equation. Fewer equation variables translate to an error rate smaller than some of the previous test phases. Additionally, the authors present a detailed error/uncertainty analysis, description of the test setup, experimental procedures, calculations, results from previous phases, and literature searches.

Walker, Seth

452

Spectral estimation and analysis of LDA data in pulsatile flow through heart valves  

NASA Astrophysics Data System (ADS)

The Laser Doppler Anemometry (LDA) measurement technique presents an inherent difficulty when spectral analysis is applied to it. The random nature of the LDA signal prohibits sampling at regular, equi-spaced, time instants. Irregular sampling presents additional variability of the spectral estimator. In order to reduce this variability, spectral analysis of LDA data is performed according to the method of direct Fourier transform of short blocks of data, as suggested by Gaster and Roberts. The LDA data is measured in a flow field distal to prosthetic heart valves with varying degrees of stenosis. The spectral estimates of velocity data sampled during the rapid closure stage of the valve are achieved with excellent frequency resolution. Important and useful information about dominant frequency peaks and preferred modes which exist in the flow, otherwise smeared or concealed in the spectral contents, are then derived from the spectral information. These modes are quantitatively analysed in light of vortex formation and related flow mechanisms. Comparative studies of normal and stenosed valves show that the preferred modes are governed by the valve geometry and dynamic behavior and are correlated to the severity of the stenosis.

Bluestein, D.; Einav, S.

1993-09-01

453

High-performance space shuttle auxiliary propellant valve system  

NASA Technical Reports Server (NTRS)

Several potential valve closures for the space shuttle auxiliary propulsion system (SS/APS) were investigated analytically and experimentally in a modeling program. The most promising of these were analyzed and experimentally evaluated in a full-size functional valve test fixture of novel design. The engineering investigations conducted for both model and scale evaluations of the SS/APS valve closures and functional valve fixture are described. Preliminary designs, laboratory tests, and overall valve test fixture designs are presented, and a final recommended flightweight SS/APS valve design is presented.

Smith, G. M.

1973-01-01

454

How valve hammer causes knocking in triplex pumps  

SciTech Connect

This article investigates valve hammer as opposed to water hammer in triplex pumps, both of which produce knocking under certain distinctly different hydraulic operations. The occurrence of water hammer is reviewed and the development of valve hammer is discussed and documented. This work examines normal valve operation and abnormal operations at higher speeds where valve lag develops and valve hammer occurs. Valve hammer results in high impact at the instant of closure which produces a bang noise and can result in part peening and possible failure.

Collier, S.L.

1983-03-28

455

Variable-Orifice Oxygen-Flow Regulator  

NASA Technical Reports Server (NTRS)

Variable-orifice flow-control valve switchable between fully and partially opened positions. Straight-through flow patch minimizes high-speed impacts of entrained particles, reducing erosion and accidental ignition. Designed for use with oxygen, also used with variety of liquids and gases.

Christianson, Rollin C.

1992-01-01

456

Role of Transcatheter Aortic Valve Implantation (TAVI) Versus Conventional Aortic Valve Replacement in the Treatment of Aortic Valve Disease  

PubMed Central

Conventional aortic valve replacement (AVR) surgery has been in clinical use since 1960. Results, particularly in high-risk populations such as the very elderly and frail, continue to improve in response to the challenges posed by this growing segment of the patient population. Transcatheter aortic valve implantation (TAVI) is a fairly recent development, performed for the first time in 2002. The last decade has seen an exponential growth in the application of this technology in higher-risk populations. Results of recent randomized prospective trials demonstrate both the future promise and current problems of the TAVI approach. Many patients deemed inoperable for AVR have been treated successfully by TAVI. However, elevated procedural and late mortality rates, excessive early and late stroke, and a significant incidence of periprosthetic aortic valve insufficiency and patient-prosthesis mismatch all suggest caution in extending this technology to patients able to undergo conventional AVR with a low risk of early or late complications. PMID:22891120

2012-01-01

457

Liquid rocket pressure regulators, relief valves, check valves, burst disks, and explosive valves. [design techniques and practices  

NASA Technical Reports Server (NTRS)

The development of and operational programs for effective use in design are presented for liquid rocket pressure regulators, relief valves, check valves, burst disks, and explosive valves. A review of the total design problem is presented, and design elements are identified which are involved in successful design. Current technology pertaining to these elements is also described. Design criteria are presented which state what rule or standard must be imposed on each essential design element to assure successful design. These criteria serve as a checklist of rules for a project manager to use in guiding a design or in assessing its adequacy. Recommended practices are included which state how to satisfy each of the criteria.

1973-01-01

458

Pneumatic Valve Operated by Multiplex Pneumatic Transmission  

NASA Astrophysics Data System (ADS)

A pneumatic system has several advantages, which are cheapness, lightweight, and reliability to human and environment. These advantages are adapted to some research areas, such as industrial lines, medical and nursing cares, and rehabilitation tools. However, the pneumatic system needs several devices; compressor, air tube, and control valve. This research aim to downsize pneumatic system. In this paper, a new method of multiplex pneumatic transmission for multi-pneumatic servo system is proposed. The valve for this system consists of two vibrators supported by springs, which was designed with simple and cheap structure. The working principle of the valve is vibrators resonance from multiplex pneumatic transmission and it is possible to work as ON/OFF valves without electric wire. Dynamic simulation was used to confirm the working principle of the resonance driving system. A prototype device confirming the principle was designed and developed based on the simulation. The experiments show that this new control system works very well to control two separated valves through single pneumatic tube.

Nishioka, Yasutaka; Suzumori, Koichi; Kanda, Takefumi; Wakimoto, Shuichi

459

Evaluation of check valve monitoring methods  

SciTech Connect

Check valves are used extensively in nuclear plant safety systems and balance-of-plant (BOP) systems. Their failures have resulted in significant maintenance efforts and, on occasion, have resulted in water hammer, overpressurization of low-pressure systems and damage to flow system components. Consequently, in recent years check valves have received considerable attention by the Nuclear Regulatory Commission (NRC) and the nuclear power industry. Oak Ridge National Laboratory (ORNL) is carrying out a comprehensive two phase aging assessment of check valves in support of the Nuclear Plant Aging Research (NPAR) program. As part of the second phase, ORNL is evaluating several developmental and/or commercially available check valve diagnostic monitoring methods; in particular, those based on measurements of acoustic emission, ultrasonics, and magnetic flux. These three methods were found to provide different (and complementary) diagnostic information. The combination of acoustic emission with either ultrasonic or magnetic flux monitoring yields a monitoring system that succeeds in providing sensitivity to detect all major check valve operating conditions. All three methods are still under development and should improve in many respects as a result of further testing and evaluation. 10 refs., 19 figs., 1 tab.

Haynes, H.D.

1989-01-01

460

Development and Characterization Testing of an Air Pulsation Valve for a Pulse Detonation Engine Supersonic Parametric Inlet Test Section  

NASA Technical Reports Server (NTRS)

In pulse detonation engines, the potential exists for gas pulses from the combustor to travel upstream and adversely affect the inlet performance of the engine. In order to determine the effect of these high frequency pulses on the inlet performance, an air pulsation valve was developed to provide air pulses downstream of a supersonic parametric inlet test section. The purpose of this report is to document the design and characterization tests that were performed on a pulsation valve that was tested at the NASA Glenn Research Center 1x1 Supersonic Wind Tunnel (SWT) test facility. The high air flow pulsation valve design philosophy and analyses performed are discussed and characterization test results are presented. The pulsation valve model was devised based on the concept of using a free spinning ball valve driven from a variable speed electric motor to generate air flow pulses at preset frequencies. In order to deliver the proper flow rate, the flow port was contoured to maximize flow rate and minimize pressure drop. To obtain sharp pressure spikes the valve flow port was designed to be as narrow as possible to minimize port dwell time.

Tornabene, Robert

2005-01-01