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Sample records for one-way valves reveals

  1. Bronchoscopic treatment of complex persistent air leaks with endobronchial one-way valves.

    PubMed

    Fiorelli, Alfonso; Costanzo, Saveria; Carelli, Emanuele; Di Costanzo, Emilio; Santini, Mario

    2016-04-01

    We reported a case series including 5 patients with persistent air-leaks refractory to standard treatment. All patients were unfit for surgery for the presence of co-morbidities and/or severe respiratory failure due to underlying lung diseases. They were successfully treated with bronchoscopic placement of endobronchial one-way valves. Air-leaks stopped in the first 24 h after the procedure in three patients and 3 and 5 days later, respectively, in the remaining two. No complications were observed and follow-up was uneventful in all patients but one died 25 days after the procedure for systemic sepsis due to peritonis. Patients with important, refractory air leaks having clinical repercussions and unfit for surgery should be early reviewed for bronchoscopic valves treatment.

  2. One-way water permeable valve via water-based superhydrophobic coatings

    NASA Astrophysics Data System (ADS)

    Mates, Joseph E.; Megaridis, Constantine M.

    2013-11-01

    Spray-cast superhydrophobic coatings have shown promise in commercial applications for fluid management due to their intrinsic low-cost, large-area capabilities and substrate independence (Schutzius et al. 2011). A technique of applying a light (< 2 gsm) water-based superhydrophobic coating on inherently hydrophilic cellulosic substrates to generate a preferred directionality for water absorption and transmission is presented. The mechanism described allows water to pass through a thin treated porous substrate in one direction under negligible pressure, but does not allow water to return from the opposite direction unless much greater pressure is applied. This pressure disparity ``window'' effectively creates a one-way fluid valve, with envisioned applications ranging from personal hygiene products, to oil-water separation and filtration. Combining SEM imaging with theoretical robustness factors (Tuteja et al. 2008), the penetration pressures are found to be tunable for application-specific designs by choosing a substrate based on limiting factors of fiber diameter and spacing. The process can also be modified with the addition of functionalized (e.g. antibacterial, conductive) nanoparticle fillers suited for the desired application.

  3. [Placement of one-way endobronchial valves to treat severe pulmonary emphysema in an 84-year-old].

    PubMed

    Carron, Kris O M

    2009-01-01

    An 84-year-old man with end-stage emphysema was hospitalised on two occasions because of an episode of severe COPD exacerbation, each time successfully treated in a classical pharmacological manner. Further analysis of a high-resolution CT chest scan revealed very pronounced destruction of the lung parenchyma in the left lower lobe. Moreover, the degree of destruction in the left lung was of a highly heterogeneous nature and fissure analysis revealed a complete left major fissure. After carefully weighing up the costs against the benefits, two one-way valves of different sizes were implanted in the orifices of the left lower lobe using video bronchoscopy. This intervention had a very satisfactory outcome with positive changes in the lung function parameters, imaging studies and quality of life. The inevitable placement in a nursing home could consequently be postponed and, at follow-up one year later, no exacerbation or pneumonia had developed since the intervention.

  4. The early detection of lung cancer during follow-up of patients undergoing endobronchial one-way valve treatment for emphysema.

    PubMed

    Fiorelli, Alfonso; Costanzo, Saveria; di Costanzo, Emilio; Santini, Mario

    2015-03-01

    We describe the early detection of lung cancer during the follow-up of two emphysematous patients undergoing endobronchial treatment with one-way valves for severe dyspnea. In both cases, the lung function improvement achieved after the valves placement allowed their surgical treatment. In additional to standard follow-up for evaluating the progression of emphysema, such patients should be enrolled in a screening program. It may allow the early detection of lung cancer with the possibility for surgery in accordance with respiratory function of patient.

  5. Combined Bone Marrow-Derived Mesenchymal Stromal Cell Therapy and One-Way Endobronchial Valve Placement in Patients with Pulmonary Emphysema: A Phase I Clinical Trial.

    PubMed

    de Oliveira, Hugo Goulart; Cruz, Fernanda Ferreira; Antunes, Mariana Alves; de Macedo Neto, Amarilio Vieira; Oliveira, Guilherme Augusto; Svartman, Fabio Munhoz; Borgonovo, Tamara; Rebelatto, Carmen Lucia Kuniyoshi; Weiss, Daniel J; Brofman, Paulo Roberto Slud; Morales, Marcelo Marcos; Lapa E Silva, José Roberto; Rocco, Patricia Rieken Macedo

    2017-03-01

    One-way endobronchial valves (EBV) insertion to reduce pulmonary air trapping has been used as therapy for chronic obstructive pulmonary disease (COPD) patients. However, local inflammation may result and can contribute to worsening of clinical status in these patients. We hypothesized that combined EBV insertion and intrabronchial administration of mesenchymal stromal cells (MSCs) would decrease the inflammatory process, thus mitigating EBV complications in severe COPD patients. This initial study sought to investigate the safety of this approach. For this purpose, a phase I, prospective, patient-blinded, randomized, placebo-controlled design was used. Heterogeneous advanced emphysema (Global Initiative for Chronic Lung Disease [GOLD] III or IV) patients randomly received either allogeneic bone marrow-derived MSCs (10(8) cells, EBV+MSC) or 0.9% saline solution (EBV) (n = 5 per group), bronchoscopically, just before insertion of one-way EBVs. Patients were evaluated 1, 7, 30, and 90 days after therapy. All patients completed the study protocol and 90-day follow-up. MSC delivery did not result in acute administration-related toxicity, serious adverse events, or death. No significant between-group differences were observed in overall number of adverse events, frequency of COPD exacerbations, or worsening of disease. Additionally, there were no significant differences in blood tests, lung function, or radiological outcomes. However, quality-of-life indicators were higher in EBV + MSC compared with EBV. EBV + MSC patients presented decreased levels of circulating C-reactive protein at 30 and 90 days, as well as BODE (Body mass index, airway Obstruction, Dyspnea, and Exercise index) and MMRC (Modified Medical Research Council) scores. Thus, combined use of EBV and MSCs appears to be safe in patients with severe COPD, providing a basis for subsequent investigations using MSCs as concomitant therapy. Stem Cells Translational Medicine 2017;6:962-969.

  6. A Biomechanical Study of Hyoid Bone and Laryngeal Movements During Swallowing Comparing the Blom Low Profile Voice Inner Cannula and Passy-Muir One Way Tracheotomy Tube Speaking Valves.

    PubMed

    Srinet, Prateek; Van Daele, Douglas J; Adam, Stewart I; Burrell, Morton I; Aronberg, Ryan; Leder, Steven B

    2015-12-01

    The aim of this prospective, consecutive, cohort study was to investigate the biomechanical effects, if any, of the Blom low profile voice inner cannula and Passy-Muir one-way tracheotomy tube speaking valves on movement of the hyoid bone and larynx during swallowing. Ten adult patients (8 male, 2 female) with an age range of 61-89 years (mean 71 years) participated. Criteria for inclusion were ≥18 years of age, English speaking, and ability to tolerate both changing to a Blom tracheotomy tube and placement of a one-way tracheotomy tube speaking valve with a fully deflated tracheotomy tube cuff. Digitized videofluoroscopic swallow studies were performed at 30 frames/s and with each patient seated upright in the lateral plane. A total of 18 swallows (three each with 5 cc bolus volumes of single contrast barium and puree + barium × 3 conditions) were analyzed for each participant. Variables evaluated included larynx-to-hyoid bone excursion (mm), maximum hyoid bone displacement (mm), and aspiration status under three randomized conditions: 1. Tracheotomy tube open with no inner cannula; 2. Tracheotomy tube with Blom valve; and 3. Tracheotomy tube with Passy-Muir valve. Blinded reliability testing with a Pearson product moment correlation was performed on 20 % of the data. Intra- and inter-rater reliability for combined measurements of larynx-to-hyoid bone excursion and maximum hyoid bone displacement was r = 0.98. Intra- and inter-rater reliability for aspiration status was 100 %. No significant differences (p > 0.05) were found for larynx-to-hyoid bone excursion and maximum hyoid bone displacement during swallowing based upon an open tracheotomy tube, Blom valve, or Passy-Muir valve. Aspiration status was identical for all three randomized conditions. The presence of a one-way tracheotomy tube speaking valve did not significantly alter two important components of normal pharyngeal swallow biomechanics, i.e., hyoid bone and laryngeal movements

  7. Optimization of one-way wave equations.

    USGS Publications Warehouse

    Lee, M.W.; Suh, S.Y.

    1985-01-01

    The theory of wave extrapolation is based on the square-root equation or one-way equation. The full wave equation represents waves which propagate in both directions. On the contrary, the square-root equation represents waves propagating in one direction only. A new optimization method presented here improves the dispersion relation of the one-way wave equation. -from Authors

  8. One-way transformation of information

    DOEpatents

    Cooper, James A.

    1989-01-01

    Method and apparatus are provided for one-way transformation of data according to multiplication and/or exponentiation modulo a prime number. An implementation of the invention permits the one way residue transformation, useful in encryption and similar applications, to be implemented by n-bit computers substantially with no increase in difficulty or complexity over a natural transformation thereby, using a modulus which is a power of two.

  9. Experimental one-way quantum computing.

    PubMed

    Walther, P; Resch, K J; Rudolph, T; Schenck, E; Weinfurter, H; Vedral, V; Aspelmeyer, M; Zeilinger, A

    2005-03-10

    Standard quantum computation is based on sequences of unitary quantum logic gates that process qubits. The one-way quantum computer proposed by Raussendorf and Briegel is entirely different. It has changed our understanding of the requirements for quantum computation and more generally how we think about quantum physics. This new model requires qubits to be initialized in a highly entangled cluster state. From this point, the quantum computation proceeds by a sequence of single-qubit measurements with classical feedforward of their outcomes. Because of the essential role of measurement, a one-way quantum computer is irreversible. In the one-way quantum computer, the order and choices of measurements determine the algorithm computed. We have experimentally realized four-qubit cluster states encoded into the polarization state of four photons. We characterize the quantum state fully by implementing experimental four-qubit quantum state tomography. Using this cluster state, we demonstrate the feasibility of one-way quantum computing through a universal set of one- and two-qubit operations. Finally, our implementation of Grover's search algorithm demonstrates that one-way quantum computation is ideally suited for such tasks.

  10. Logica's one-way VSAT system

    NASA Astrophysics Data System (ADS)

    Barrington-Cook, J. I.

    1991-01-01

    Logica has recently produced the main 'collection and forwarding' element for a comprehensive one-way VSAT system. The system is designed to utilize the extra bandwidth available from direct-to-home broadcasts using the MAC/packet television standard, in order to provide point-to-multipoint data transmission via satellite. The expectation of very large volumes of supply for standard decoders, together with the large amount of bandwidth available, suggest that extremely low cost data transmission may become available. The system is designed to provide the necessary infrastructure to allow this bulk data, low cost approach to be offered for small scale and ad-hoc data transmission.

  11. One-way regular electromagnetic mode immune to backscattering.

    PubMed

    Deng, Xiaohua; Hong, Lujun; Zheng, Xiaodong; Shen, Linfang

    2015-05-10

    In this paper, we present a basic model of robust one-way electromagnetic modes at microwave frequencies, which is formed by a semi-infinite gyromagnetic yttrium-iron-garnet with dielectric cladding terminated by a metal plate. It is shown that this system supports not only one-way surface magnetoplasmons (SMPs) but also a one-way regular mode, which is guided by the mechanism of total internal reflection. Like one-way SMPs, the one-way regular mode can be immune to backscattering, and two types of one-way modes together make up a complete dispersion band for the system.

  12. Quantification of Calcified Particles in Human Valve Tissue Reveals Asymmetry of Calcific Aortic Valve Disease Development

    PubMed Central

    Yabusaki, Katsumi; Hutcheson, Joshua D.; Vyas, Payal; Bertazzo, Sergio; Body, Simon C.; Aikawa, Masanori; Aikawa, Elena

    2016-01-01

    Recent studies indicated that small calcified particles observable by scanning electron microscopy (SEM) may initiate calcification in cardiovascular tissues. We hypothesized that if the calcified particles precede gross calcification observed in calcific aortic valve disease (CAVD), they would exhibit a regional asymmetric distribution associated with CAVD development, which always initiates at the base of aortic valve leaflets adjacent to the aortic outflow in a region known as the fibrosa. Testing this hypothesis required counting the calcified particles in histological sections of aortic valve leaflets. SEM images, however, do not provide high contrast between components within images, making the identification and quantification of particles buried within tissue extracellular matrix difficult. We designed a new unique pattern-matching based technique to allow for flexibility in recognizing particles by creating a gap zone in the detection criteria that decreased the influence of non-particle image clutter in determining whether a particle was identified. We developed this flexible pattern particle-labeling (FpPL) technique using synthetic test images and human carotid artery tissue sections. A conventional image particle counting method (preinstalled in ImageJ) did not properly recognize small calcified particles located in noisy images that include complex extracellular matrix structures and other commonly used pattern-matching methods failed to detect the wide variation in size, shape, and brightness exhibited by the particles. Comparative experiments with the ImageJ particle counting method demonstrated that our method detected significantly more (p < 2 × 10−7) particles than the conventional method with significantly fewer (p < 0.0003) false positives and false negatives (p < 0.0003). We then applied the FpPL technique to CAVD leaflets and showed a significant increase in detected particles in the fibrosa at the base of the leaflets (p

  13. VALVE

    DOEpatents

    Arkelyan, A.M.; Rickard, C.L.

    1962-04-17

    A gate valve for controlling the flow of fluid in separate concentric ducts or channels by means of a single valve is described. In one position, the valve sealing discs engage opposed sets of concentric ducts leading to the concentric pipes defining the flow channels to block flow therethrough. In another position, the discs are withdrawn from engagement with the opposed ducts and at the same time a bridging section is interposed therebetween to define concentric paths coextensive with and connecting the opposed ducts to facilitate flow therebetween. A wedge block arrangement is employed with each sealing disc to enable it to engage the ducts. The wedge block arrangement also facilitates unobstructcd withdrawal of the discs out of the intervening space between the sets of ducts. (AEC)

  14. Valve

    DOEpatents

    Cho, Nakwon

    1980-01-01

    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.

  15. Improved technique for one-way transformation of information

    DOEpatents

    Cooper, J.A.

    1987-05-11

    Method and apparatus are provided for one-way transformation of data according to multiplication and/or exponentiation modulo a prime number. An implementation of the invention permits the one way residue transformation, useful in encryption and similar applications, to be implemented by n-bit computers substantially with no increase in difficulty or complexity over a natural transformation thereby, using a modulus which is a power of two. 9 figs.

  16. Criteria of backscattering in chiral one-way photonic crystals

    NASA Astrophysics Data System (ADS)

    Cheng, Pi-Ju; Chang, Shu-Wei

    2016-03-01

    Optical isolators are important devices in photonic circuits. To reduce the unwanted reflection in a robust manner, several setups have been realized using nonreciprocal schemes. In this study, we show that the propagating modes in a strongly-guided chiral photonic crystal (no breaking of the reciprocity) are not backscattering-immune even though they are indeed insensitive to many types of scatters. Without the protection from the nonreciprocity, the backscattering occurs under certain circumstances. We present a perturbative method to calculate the backscattering of chiral photonic crystals in the presence of chiral/achiral scatters. The model is, essentially, a simplified analogy to the first-order Born approximation. Under reasonable assumptions based on the behaviors of chiral photonic modes, we obtained the expression of reflection coefficients which provides criteria for the prominent backscattering in such chiral structures. Numerical examinations using the finite-element method were also performed and the results agree well with the theoretical prediction. From both our theory and numerical calculations, we find that the amount of backscattering critically depends on the symmetry of scatter cross sections. Strong reflection takes place when the azimuthal Fourier components of scatter cross sections have an order l of 2. Chiral scatters without these Fourier components would not efficiently reflect the chiral photonic modes. In addition, for these chiral propagating modes, disturbances at the most significant parts of field profiles do not necessarily result in the most effective backscattering. The observation also reveals what types of scatters or defects should be avoided in one-way applications of chiral structures in order to minimize the backscattering.

  17. One-way electromagnetic waveguide using multiferroic Fibonacci superlattices

    NASA Astrophysics Data System (ADS)

    Tang, Zhenghua; Lei, Dajun; Huang, Jianquan; Jin, Gui; Qiu, Feng; Yan, Wenyan

    2015-12-01

    The multiferroic Fibonacci superlattices (MFSs) are composed of single-phase multiferroic domains with polarization and magnetization according to the rule of Fibonacci sequence. We propose to construct a one-way electromagnetic waveguide by the MFSs. The forbidden band structures of the MFSs for the forward and backward electromagnetic waves are not completely overlapped, and an obvious translation between them occurs around the fixed point ω bar = 1 with broken time-reversal and space inversion symmetries (TRSIS), which indicates the existence of one-way electromagnetic modes in the MFSs. Transmission spectrum is utilized to present this property and to indicate further one-way electromagnetic modes lying within the polaritonic band gap. The maximum forbidden bandwidth (divided by midgap frequency) of 5.4% for the backward electromagnetic wave (BEW) is found, in which the forward electromagnetic wave (FEW) can pass. The functions of one-way propagation modes and polaritonic band gap integrated into the MFSs can miniaturize the one-way photonic devices. The properties can also be applied to construct compact microwave isolators.

  18. Efficient quantum circuits for one-way quantum computing.

    PubMed

    Tanamoto, Tetsufumi; Liu, Yu-Xi; Hu, Xuedong; Nori, Franco

    2009-03-13

    While Ising-type interactions are ideal for implementing controlled phase flip gates in one-way quantum computing, natural interactions between solid-state qubits are most often described by either the XY or the Heisenberg models. We show an efficient way of generating cluster states directly using either the imaginary SWAP (iSWAP) gate for the XY model, or the sqrt[SWAP] gate for the Heisenberg model. Our approach thus makes one-way quantum computing more feasible for solid-state devices.

  19. One-way quantum computation with circuit quantum electrodynamics

    SciTech Connect

    Wu Chunwang; Han Yang; Chen Pingxing; Li Chengzu; Zhong Xiaojun

    2010-03-15

    In this Brief Report, we propose a potential scheme to implement one-way quantum computation with circuit quantum electrodynamics (QED). Large cluster states of charge qubits can be generated in just one step with a superconducting transmission line resonator (TLR) playing the role of a dispersive coupler. A single-qubit measurement in the arbitrary basis can be implemented using a single electron transistor with the help of one-qubit gates. By examining the main decoherence sources, we show that circuit QED is a promising architecture for one-way quantum computation.

  20. Detail of one way mirror, mail slot, and electrical box ...

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

    Detail of one way mirror, mail slot, and electrical box at sentry post no. 3, top of east stairs near the end of second floor corridor - March Air Force Base, Strategic Air Command, Combat Operations Center, 5220 Riverside Drive, Moreno Valley, Riverside County, CA

  1. One-way quantum computing in the optical frequency comb.

    PubMed

    Menicucci, Nicolas C; Flammia, Steven T; Pfister, Olivier

    2008-09-26

    One-way quantum computing allows any quantum algorithm to be implemented easily using just measurements. The difficult part is creating the universal resource, a cluster state, on which the measurements are made. We propose a scalable method that uses a single, multimode optical parametric oscillator (OPO). The method is very efficient and generates a continuous-variable cluster state, universal for quantum computation, with quantum information encoded in the quadratures of the optical frequency comb of the OPO.

  2. One-way Ponderomotive Barrier in a Uniform Magnetic Field

    SciTech Connect

    I.Y. Dodin; N.J. Fisch

    2005-02-14

    The possibility of an asymmetric ponderomotive barrier in a nonuniform dc magnetic field by high-frequency radiation near the cyclotron resonance for selected plasma species was contemplated in Physics of Plasmas 11 (November 2004) 5046-5064. Here we show that a similar one-way barrier, which reflects particles incident from one side while transmitting those incident from the opposite side, can be produced also in a uniform magnetic field, entirely due to inhomogeneity of high-frequency drive.

  3. On measuring the one-way speed of light

    NASA Astrophysics Data System (ADS)

    Spavieri, G.

    2012-03-01

    The crucial problem of how to synchronize clocks and measure the one-way speed of light was originally discussed by Poincaré and Einstein. After being neglected for many decades, the Poincaré-Einstein problem of synchronization revived in 1977 with the work of Mansouri and Sexl, by which the one-way speed remains undetermined, allowing for unequal values of the speed of light in opposite directions. We review this problem in the framework of relativistic theories that assume clock-retardation and rod-contraction. We show that, for preferred frame theories, convection or "open" currents yield a magnetic field that depends on the velocity v with respect to the preferred frame S o . We also outline an experiment, based on Faraday's law of induction, that can determine the velocity v, identify S o , and test special relativity versus preferred frame theories. This result resolves the Poincaré-Einstein problem and shows that, in principle, the one-way speed c can be measured.

  4. Successive positive contrast in one-way avoidance learning.

    PubMed

    Cándido, Antonio; Maldonado, Antonio; Rodríguez, Alicia; Morales, Alberto

    2002-04-01

    The main finding of these experiments was a positive contrast effect in one-way avoidance learning. Experiment 1 showed that increasing safety time during one-way avoidance training led to improved performance, surpassing that of a control group that had received the high reward (safe time) from the beginning of training. Experiment 2 showed that a similar positive contrast effect occurred when the time spent in the danger compartment before the onset of the warning signal was shortened. These results suggest that time spent in a safe context acts as a reinforcer of the avoidance response; however, its incentive value depends not only on its duration, but also on the length of the time spent in the danger compartment before the onset of the signal. Overall, results also suggest that the avoidance response is a mixture of flight (motivated by fear) and approach (to a safe place) behaviour. The specific weight of the flight or approach component may be a function of the time and the amount of activation of each emotional state (fear or relief) due to opponent homeostatic compensatory processes that occur in the danger and safe compartments during one-way avoidance learning.

  5. One-way visibility using two parallel aerosol clouds.

    PubMed

    Alyones, Sharhabeel; Bruce, Charles W; Granado, Michael; Jelinek, Al V

    2015-01-01

    In this article, we experimentally and theoretically test the range of applicability of a patent that predicts one-way visibility through two successive parallel aerosol clouds, one scattering dominant and the other absorption dominant. A laboratory environment experiment has been designed to determine the ranges of transmissivity and contrast enhancement that might be of interest for military applications. In this study we show that transmissivities in the several percent range and lower are essential for any reasonable contrast enhancement between the two sides of the clouds.

  6. Cutting edge: back to "one-way" germinal centers.

    PubMed

    Meyer-Hermann, Michael E; Maini, Philip K

    2005-03-01

    The present status of germinal center (GC) research is revisited using in silico simulations based on recent lymphocyte motility data in mice. The generally adopted view of several rounds of somatic hypermutations and positive selection is analyzed with special emphasis on the spatial organization of the GC reaction. We claim that the development of dark zones is not necessary for successful GC reactions to develop. We find that a recirculation of positively selected centrocytes to the dark zone is rather unlikely. Instead we propose a scenario that combines a multiple-step mutation and selection concept with a "one-way" GC in the sense of cell migration.

  7. Universal linear Bogoliubov transformations through one-way quantum computation

    SciTech Connect

    Ukai, Ryuji; Yoshikawa, Jun-ichi; Iwata, Noriaki; Furusawa, Akira; Loock, Peter van

    2010-03-15

    We show explicitly how to realize an arbitrary linear unitary Bogoliubov (LUBO) transformation on a multimode quantum state through homodyne-based one-way quantum computation. Any LUBO transformation can be approximated by means of a fixed, finite-sized, sufficiently squeezed Gaussian cluster state that allows for the implementation of beam splitters (in form of three-mode connection gates) and general one-mode LUBO transformations. In particular, we demonstrate that a linear four-mode cluster state is a sufficient resource for an arbitrary one-mode LUBO transformation. Arbitrary-input quantum states including non-Gaussian states could be efficiently attached to the cluster through quantum teleportation.

  8. Acoustic one-way open tunnel by using metasurface

    NASA Astrophysics Data System (ADS)

    Zhu, Yi-Fan; Zou, Xin-Ye; Liang, Bin; Cheng, Jian-Chun

    2015-09-01

    We design and experimentally demonstrate an acoustic tunnel completely open for substances like fluids or other energy fluxes to exchange while allowing sound to pass only in one direction. This significant feature is based on a distinctive mechanism using metasurface pairs to yield asymmetric extraordinary reflections along opposite directions. Theoretical analysis is presented to analytically predict the trajectory of the wave. The experimental results agree well with the numerical results and the theoretical predictions. Our design may pave the way to more versatile acoustic one-way devices with potential applications in many scenarios like duct noise control and ultrasonic therapy.

  9. One-way glass for microwaves using nonreciprocal metamaterials.

    PubMed

    Degiron, A; Smith, D R

    2014-05-01

    We introduce a class of nonreciprocal metamaterials based on composite assemblies of metallic and biased ferrimagnetic elements. We show that such structures act as ultrathin one-way glasses due to the competition between two modes at the surface of the ferrimagnetic elements--a low-loss surface wave that transmits the signal on the other side of the structure and a surface spin-wave resonance that produces strong isolation levels. These findings can be adapted to existing metamaterial geometries, offering a blueprint to achieve unidirectional propagation in a variety of artificial media at radio, microwave, and millimeter wave frequencies.

  10. One-way helical electromagnetic wave propagation supported by magnetized plasma

    PubMed Central

    Yang, Biao; Lawrence, Mark; Gao, Wenlong; Guo, Qinghua; Zhang, Shuang

    2016-01-01

    In this paper we reveal the presence of photonic one-way helical surface states in a simple natural system- magnetized plasma. The application of an external magnetic field to a bulk plasma body not only breaks time-reversal-symmetry but also leads to separation of Equi-Frequency Contour surfaces (EFCs) to form topologically nontrivial gaps in k space. Interestingly, these EFCs support topologically protected surface states. We numerically investigate an interface between magnetized plasma, using a realistic model for parameter dispersion, and vacuum, to confirm the existence of one-way scatter-immune helical surface states. Unlike previous proposals for achieving photonic one-way propagation, our scheme does not require the use of artificial structures and should therefore be simple to implement experimentally. PMID:26883883

  11. One way Doppler extractor. Volume 1: Vernier technique

    NASA Technical Reports Server (NTRS)

    Blasco, R. W.; Klein, S.; Nossen, E. J.; Starner, E. R.; Yanosov, J. A.

    1974-01-01

    A feasibility analysis, trade-offs, and implementation for a One Way Doppler Extraction system are discussed. A Doppler error analysis shows that quantization error is a primary source of Doppler measurement error. Several competing extraction techniques are compared and a Vernier technique is developed which obtains high Doppler resolution with low speed logic. Parameter trade-offs and sensitivities for the Vernier technique are analyzed, leading to a hardware design configuration. A detailed design, operation, and performance evaluation of the resulting breadboard model is presented which verifies the theoretical performance predictions. Performance tests have verified that the breadboard is capable of extracting Doppler, on an S-band signal, to an accuracy of less than 0.02 Hertz for a one second averaging period. This corresponds to a range rate error of no more than 3 millimeters per second.

  12. One way Doppler Extractor. Volume 2: Digital VCO technique

    NASA Technical Reports Server (NTRS)

    Nossen, E. J.; Starner, E. R.

    1974-01-01

    A feasibility analysis and trade-offs for a one-way Doppler extractor using digital VCO techniques is presented. The method of Doppler measurement involves the use of a digital phase lock loop; once this loop is locked to the incoming signal, the precise frequency and hence the Doppler component can be determined directly from the contents of the digital control register. The only serious error source is due to internally generated noise. Techniques are presented for minimizing this error source and achieving an accuracy of 0.01 Hz in a one second averaging period. A number of digitally controlled oscillators were analyzed from a performance and complexity point of view. The most promising technique uses an arithmetic synthesizer as a digital waveform generator.

  13. One-way ANOVA based on interval information

    NASA Astrophysics Data System (ADS)

    Hesamian, Gholamreza

    2016-08-01

    This paper deals with extending the one-way analysis of variance (ANOVA) to the case where the observed data are represented by closed intervals rather than real numbers. In this approach, first a notion of interval random variable is introduced. Especially, a normal distribution with interval parameters is introduced to investigate hypotheses about the equality of interval means or test the homogeneity of interval variances assumption. Moreover, the least significant difference (LSD method) for investigating multiple comparison of interval means is developed when the null hypothesis about the equality of means is rejected. Then, at a given interval significance level, an index is applied to compare the interval test statistic and the related interval critical value as a criterion to accept or reject the null interval hypothesis of interest. Finally, the method of decision-making leads to some degrees to accept or reject the interval hypotheses. An applied example will be used to show the performance of this method.

  14. Acoustic topological insulator and robust one-way sound transport

    NASA Astrophysics Data System (ADS)

    He, Cheng; Ni, Xu; Ge, Hao; Sun, Xiao-Chen; Chen, Yan-Bin; Lu, Ming-Hui; Liu, Xiao-Ping; Chen, Yan-Feng

    2016-12-01

    Topological design of materials enables topological symmetries and facilitates unique backscattering-immune wave transport. In airborne acoustics, however, the intrinsic longitudinal nature of sound polarization makes the use of the conventional spin-orbital interaction mechanism impossible for achieving band inversion. The topological gauge flux is then typically introduced with a moving background in theoretical models. Its practical implementation is a serious challenge, though, due to inherent dynamic instabilities and noise. Here we realize the inversion of acoustic energy bands at a double Dirac cone and provide an experimental demonstration of an acoustic topological insulator. By manipulating the hopping interaction of neighbouring ’atoms’ in this new topological material, we successfully demonstrate the acoustic quantum spin Hall effect, characterized by robust pseudospin-dependent one-way edge sound transport. Our results are promising for the exploration of new routes for experimentally studying topological phenomena and related applications, for example, sound-noise reduction.

  15. Destination Mars: Colonization via Initial One-way Missions

    NASA Astrophysics Data System (ADS)

    Schulze-Makuch, D.; Davies, P.

    Earth is located in a dangerous part of the universe. Threats to life on Earth are manifold and range from asteroid impacts to supernova explosions and from supervolcano eruptions to human-induced disasters. If the survival of the human species is to be ensured for the long term, then life on Earth has to spread to other planetary bodies. Mars is the most Earth-like planet we currently know and is the second closest planet; further it possesses a moderate surface gravity, an atmosphere, abundant water and carbon dioxide, together with a range of essential minerals. Thus, Mars is ideally suited to be a first colonization target. Here we argue that the most practical way that this can be accomplished is via a series of initial one-way human missions.

  16. Epidemic spreading on one-way-coupled networks

    NASA Astrophysics Data System (ADS)

    Wang, Lingna; Sun, Mengfeng; Chen, Shanshan; Fu, Xinchu

    2016-09-01

    Numerous real-world networks (e.g., social, communicational, and biological networks) have been observed to depend on each other, and this results in interconnected networks with different topology structures and dynamics functions. In this paper, we focus on the scenario of epidemic spreading on one-way-coupled networks comprised of two subnetworks, which can manifest the transmission of some zoonotic diseases. By proposing a mathematical model through mean-field approximation approach, we prove the global stability of the disease-free and endemic equilibria of this model. Through the theoretical and numerical analysis, we obtain interesting results: the basic reproduction number R0 of the whole network is the maximum of the basic reproduction numbers of the two subnetworks; R0 is independent of the cross-infection rate and cross contact pattern; R0 increases rapidly with the growth of inner infection rate if the inner contact pattern is scale-free; in order to eradicate zoonotic diseases from human beings, we must simultaneously eradicate them from animals; bird-to-bird infection rate has bigger impact on the human's average infected density than bird-to-human infection rate.

  17. Dynamics of cold atoms crossing a one-way barrier

    NASA Astrophysics Data System (ADS)

    Thorn, Jeremy J.; Schoene, Elizabeth A.; Li, Tao; Steck, Daniel A.

    2009-06-01

    We implemented an optical one-way potential barrier that allows ultracold R87b atoms to transmit through when incident on one side of the barrier but reflect from the other. This asymmetric barrier is a realization of Maxwell’s demon, which can be employed to produce phase-space compression and has implications for cooling atoms and molecules not amenable to standard laser-cooling techniques. The barrier comprises two focused Gaussian laser beams that intersect the focus of a far-off-resonant single-beam optical dipole trap that holds the atoms. The main barrier beam presents a state-dependent potential to incident atoms, while the repumping barrier beam optically pumps atoms to a trapped state. We investigated the robustness of the barrier asymmetry to changes in the barrier-beam separation, the initial atomic potential energy, the intensity of the second beam, and the detuning of the first beam. We performed simulations of the atomic dynamics in the presence of the barrier, showing that the initial three-dimensional momentum distribution plays a significant role, and that light-assisted collisions are likely the dominant loss mechanism. We also carefully examined the relationship to Maxwell’s demon and explicitly accounted for the apparent decrease in entropy for our particular system.

  18. Virulence conversion of Legionella pneumophila: a one-way phenomenon.

    PubMed Central

    Catrenich, C E; Johnson, W

    1988-01-01

    Previous investigations have shown that Legionella pneumophila converts from virulence to avirulence after passage on supplemented Mueller-Hinton (SMH) agar and may convert back to virulence after passage in guinea pigs. However, there is no additional information concerning the apparent interconversion of virulent and avirulent derivatives of L. pneumophila cultures. We investigated the stability of a parental virulent culture and its avirulent derivatives and the growth and viability of these cultures on charcoal-yeast extract (CYE) and SMH agars. Avirulent derivatives of a highly virulent L. pneumophila culture were obtained by passage of the virulent parent culture on SMH agar. The only time a virulent L. pneumophila culture was recoverable from an avirulent culture was when the avirulent culture was derived from a saline suspension of a virulent culture which had been passaged only five times on SMH agar. When an avirulent culture was derived from a virulent culture passaged 25 times on SMH agar or from an isolated colony which grew on a SMH agar plate, we were unable to recover a virulent culture after successive passage through guinea pigs. These results suggest that the conversion process which occurs between virulent and avirulent forms of L. pneumophila is a one-way phenomenon from virulence to avirulence and that stable avirulent derivatives can be isolated. Furthermore, our findings suggest that SMH agar acts as a selective medium for the growth of avirulent L. pneumophila, and growth on SMH agar may be a phenotypic marker for avirulence. Virulent cells, although unable to grow on SMH agar, may remain viable for several passages on SMH agar and propagate when inoculated into guinea pigs. Images PMID:3182073

  19. A new periodogram using one-way analysis of variance for circadian rhythms.

    PubMed

    Shono, M; Shono, H; Ito, Y; Muro, M; Maeda, Y; Sugimori, H

    2000-06-01

    A new periodogram was proposed using one-way analysis of variance (ANOVA), termed ANOVA periodogram, in order to reveal a precise significant periodicity. Thirty 3-day complex computer-simulated time series with known periodicity (24 h) and three 2-h data-missing occurring periodically (23 h, 20 min) were used to compare the ANOVA periodogram with Enright's one. In results, the ANOVA periodogram was superior to Enright's periodogram in the accuracy of assessing the major periodicity.

  20. 21 CFR 868.5870 - Nonrebreathing valve.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...) Identification. A nonrebreathing valve is a one-way valve that directs breathing gas flow to the patient and vents exhaled gases into the atmosphere. (b) Classification. Class II (performance standards)....

  1. One-way light transport controlled by synthetic magnetic fluxes and {\\mathscr{P}}{\\mathscr{T}}-symmetric resonators

    NASA Astrophysics Data System (ADS)

    Jin, L.; Wang, P.; Song, Z.

    2017-01-01

    Controlled directional light propagation using optical nonlinearity has previously been proposed. Here, we propose a one-way optical device with linear elements controlled by synthetic magnetic fluxes. The device consists of two parity–time symmetric side-coupled resonators with balanced gain and loss. The gain and loss break the reflection symmetry and the magnetic fluxes break the transmission symmetry. Through tuning the magnetic fluxes, reflectionless full transmission in one direction and transmissionless full reflection in the opposite direction can be achieved. The device acts as a light-checking valve, preventing wave propagation in one direction. The proposed one-way transporter uses the nonreciprocity induced by non-Hermiticity and magnetic fluxes without applying nonlinearity. We anticipate that our findings will be useful for optical control and manipulation.

  2. Three-dimensional study of a one-way, flexible magnetorheological elastomer-based micro fluid transport system

    NASA Astrophysics Data System (ADS)

    Behrooz, Majid; Gordaninejad, Faramarz

    2016-09-01

    This paper presents a three-dimensional study of a controllable flexible magnetically-activated micropump. The tubular micropump employs magnetically induced deformation of magnetorheological elastomer and one-way flexible conical valves for fluid transport. Three-dimensional magneto-fluid-solid interaction analysis is employed to investigate the performance of the system. The effects of key material, geometric, and magnetic parameters on the effectiveness of the system are examined. It is demonstrated that the proposed system can propel the fluid unidirectionally, and the volume of the transported fluid is significantly affected by some of the design parameters.

  3. One-way invisible cloak using parity-time symmetric transformation optics.

    PubMed

    Zhu, Xuefeng; Feng, Liang; Zhang, Peng; Yin, Xiaobo; Zhang, Xiang

    2013-08-01

    We propose a one-way invisible cloak using transformation optics of parity-time (PT) symmetric optical materials. At the spontaneous PT-symmetry breaking point, light is scattered only for incidence along one direction since the phase-matching condition is unidirectionally satisfied, making the cloak one-way invisible. Moreover, optical scattering from the one-way cloak can be further engineered to realize more interesting effects, for example, creating a unidirectional optical illusion of the concealed object.

  4. Aerodynamic Characteristics of Tracheostomy Speaking Valves.

    ERIC Educational Resources Information Center

    Fornataro-Clerici, Lisa; Zajac, David J.

    1993-01-01

    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.…

  5. 47 CFR 90.490 - One-way paging operations in the private services.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... directly from telephone positions in the public switched telephone network. When land stations are multiple... 47 Telecommunication 5 2012-10-01 2012-10-01 false One-way paging operations in the private... SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Paging Operations § 90.490 One-way...

  6. 47 CFR 90.490 - One-way paging operations in the private services.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... directly from telephone positions in the public switched telephone network. When land stations are multiple... 47 Telecommunication 5 2014-10-01 2014-10-01 false One-way paging operations in the private... SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Paging Operations § 90.490 One-way...

  7. On the Experimental Determination of the One-Way Speed of Light

    ERIC Educational Resources Information Center

    Perez, Israel

    2011-01-01

    In this paper the question of the isotropy of the one-way speed of light is addressed from an experimental perspective. In particular, we analyse two experimental methods commonly used in its determination. The analysis is aimed at clarifying the view that the one-way speed of light cannot be determined by techniques in which physical entities…

  8. Nonlinear behavior analysis of spur gear pairs with a one-way clutch

    NASA Astrophysics Data System (ADS)

    Gill-Jeong, Cheon

    2007-04-01

    Nonlinear behavior analysis of a paired spur gear system with a one-way clutch was used to verify whether a one-way clutch is effective for reducing torsional vibration. The dynamic responses were studied over a wide frequency range by speed sweeping to check the nonlinear behavior using numerical integration. The gear system with a one-way clutch showed typical nonlinear behavior, such as softening nonlinearity and jump phenomena. The oscillating component of the dynamic transmission error was reduced over the entire frequency range compared to a system without a one-way clutch, and double-side contact could be prevented, even with very small backlash. Installing a one-way clutch on both sides of the gear system was more effective at mitigating the negative effects of various parameter changes than installing one only on the input or output side.

  9. One-way membrane trafficking of SOS in receptor-triggered Ras activation

    PubMed Central

    Christensen, Sune M.; Tu, Hsiung-Lin; Jun, Jesse E.; Alvarez, Steven; Triplet, Meredith G.; Iwig, Jeffrey S.; Yadav, Kamlesh K.; Bar-Sagi, Dafna; Roose, Jeroen P.; Groves, Jay T.

    2016-01-01

    SOS is a key activator of the small GTPase Ras. In cells, SOS-Ras signaling is thought to be initiated predominantly by membrane-recruitment of SOS via the adaptor Grb2 and balanced by rapidly reversible Grb2:SOS binding kinetics. However, SOS has multiple protein and lipid interactions that provide linkage to the membrane. In reconstituted membrane experiments, these Grb2-independent interactions are sufficient to retain SOS on the membrane for many minutes, during which a single SOS molecule can processively activate thousands of Ras molecules. These observations raise questions concerning how receptors maintain control of SOS in cells and how membrane-recruited SOS is ultimately released. We addressed these questions in quantitative reconstituted SOS-deficient chicken B cell signaling systems combined with single molecule measurements in supported membranes. These studies reveal an essentially one-way trafficking process in which membrane-recruited SOS remains trapped on the membrane and continuously activates Ras until it is actively removed via endocytosis. PMID:27501536

  10. Evidence of one-way flow bioaccumulation of gold nanoparticles across two trophic levels

    NASA Astrophysics Data System (ADS)

    Larguinho, Miguel; Correia, Daniela; Diniz, Mário S.; Baptista, Pedro V.

    2014-08-01

    This work reports a one-way flow bioaccumulation of gold nanoparticles (AuNPs) in aquatic organisms between two trophic levels. First, Dunaliella salina cells were exposed to citrate-capped AuNPs at different concentrations and during distinct exposure periods to assess internalization and behavior. Afterward, D. salina was incubated with both citrate-capped and functionalized (PEGylated) AuNPs for 24 h and later fed to Mytilus galloprovincialis. Analysis was carried out to assess Au content, histological differences and oxidative stress. These algae were fed to the model organism M. galloprovincialis (Mediterranean mussel) as it is considered of major importance for assessing toxic effects and bioaccumulation of different pollutants in aquatic environments. Elemental Au analysis revealed an uptake of about 76 % of the initial amount of AuNPs (and 36 % for PEGylated AuNPs) in microalgae. Mussel gills and digestive gland showed variable Au content in individuals fed with D. salina previously exposed to AuNPs. No significant morphological alterations were observed in D. salina or mussel digestive glands. Glutathione-s-transferase activity and total antioxidant capacity were assessed as oxidative stress biomarkers showing that AuNPs are not prone to trigger the induction of defenses against oxidative stress.

  11. Heimlich valve and pneumothorax.

    PubMed

    Gogakos, Apostolos; Barbetakis, Nikolaos; Lazaridis, George; Papaiwannou, Antonis; Karavergou, Anastasia; Lampaki, Sofia; Baka, Sofia; Mpoukovinas, Ioannis; Karavasilis, Vasilis; Kioumis, Ioannis; Pitsiou, Georgia; Katsikogiannis, Nikolaos; Tsakiridis, Kosmas; Rapti, Aggeliki; Trakada, Georgia; Zissimopoulos, Athanasios; Tsirgogianni, Katerina; Zarogoulidis, Konstantinos; Zarogoulidis, Paul

    2015-03-01

    The Heimlich valve is a small one-way valve used for chest drainage that empties into a flexible collection device and prevents return of gases or fluids into the pleural space. The Heimlich valve is less than 13 cm (5 inches) long and facilitates patient ambulation. Currently there are several systems in the market. It can be used in many patients instead of a traditional water seal drainage system. The Heimlich chest drainage valve was developed so that the process of draining the pleural cavity could be accomplished in a safe, relatively simple, and efficient manner. This valve system has replaced the cumbersome underwater drainage bottle system. Moreover; the Heimlich valve system connects to chest tubing and allows fluid and air to pass in one direction only. This system functions in any position, and it does not ever need to be clamped, a regulated suction can be attached to it if necessary. The valve drains into a plastic bag that can be held at any level, allowing the patient undergoing chest drainage to be ambulatory simply by carrying the bag. In the current mini review we will present the Heimlich valve system and method of insertion.

  12. Heimlich valve and pneumothorax

    PubMed Central

    Gogakos, Apostolos; Barbetakis, Nikolaos; Lazaridis, George; Papaiwannou, Antonis; Karavergou, Anastasia; Lampaki, Sofia; Baka, Sofia; Mpoukovinas, Ioannis; Karavasilis, Vasilis; Kioumis, Ioannis; Pitsiou, Georgia; Katsikogiannis, Nikolaos; Tsakiridis, Kosmas; Rapti, Aggeliki; Trakada, Georgia; Zissimopoulos, Athanasios; Tsirgogianni, Katerina; Zarogoulidis, Konstantinos

    2015-01-01

    The Heimlich valve is a small one-way valve used for chest drainage that empties into a flexible collection device and prevents return of gases or fluids into the pleural space. The Heimlich valve is less than 13 cm (5 inches) long and facilitates patient ambulation. Currently there are several systems in the market. It can be used in many patients instead of a traditional water seal drainage system. The Heimlich chest drainage valve was developed so that the process of draining the pleural cavity could be accomplished in a safe, relatively simple, and efficient manner. This valve system has replaced the cumbersome underwater drainage bottle system. Moreover; the Heimlich valve system connects to chest tubing and allows fluid and air to pass in one direction only. This system functions in any position, and it does not ever need to be clamped, a regulated suction can be attached to it if necessary. The valve drains into a plastic bag that can be held at any level, allowing the patient undergoing chest drainage to be ambulatory simply by carrying the bag. In the current mini review we will present the Heimlich valve system and method of insertion. PMID:25861609

  13. One-way quantum deficit and quantum coherence in the anisotropic XY chain

    NASA Astrophysics Data System (ADS)

    Ye, Biao-Liang; Li, Bo; Zhao, Li-Jun; Zhang, Hai-Jun; Fei, Shao-Ming

    2017-03-01

    In this study, we investigate pairwise non-classical correlations measured using a one-way quantum deficit as well as quantum coherence in the XY spin-1/2 chain in a transverse magnetic field for both zero and finite temperatures. The analytical and numerical results of our investigations are presented. In the case when the temperature is zero, it is shown that the one-way quantum deficit can characterize quantum phase transitions as well as quantum coherence. We find that these measures have a clear critical point at λ = 1. When λ ≤ 1, the one-way quantum deficit has an analytical expression that coincides with the relative entropy of coherence. We also study an XX model and an Ising chain at the finite temperatures.

  14. Quantum de Finetti Theorem under Fully-One-Way Adaptive Measurements.

    PubMed

    Li, Ke; Smith, Graeme

    2015-04-24

    We prove a version of the quantum de Finetti theorem: permutation-invariant quantum states are well approximated as a probabilistic mixture of multifold product states. The approximation is measured by distinguishability under measurements that are implementable by fully-one-way local operations and classical communication (LOCC). Our result strengthens Brandão and Harrow's de Finetti theorem where a kind of partially-one-way LOCC measurements was used for measuring the approximation, with essentially the same error bound. As main applications, we show (i) a quasipolynomial-time algorithm which detects multipartite entanglement with an amount larger than an arbitrarily small constant (measured with a variant of the relative entropy of entanglement), and (ii) a proof that in quantum Merlin-Arthur proof systems, polynomially many provers are not more powerful than a single prover when the verifier is restricted to one-way LOCC operations.

  15. Quantum de Finetti Theorem under Fully-One-Way Adaptive Measurements

    NASA Astrophysics Data System (ADS)

    Li, Ke; Smith, Graeme

    2015-04-01

    We prove a version of the quantum de Finetti theorem: permutation-invariant quantum states are well approximated as a probabilistic mixture of multifold product states. The approximation is measured by distinguishability under measurements that are implementable by fully-one-way local operations and classical communication (LOCC). Our result strengthens Brandão and Harrow's de Finetti theorem where a kind of partially-one-way LOCC measurements was used for measuring the approximation, with essentially the same error bound. As main applications, we show (i) a quasipolynomial-time algorithm which detects multipartite entanglement with an amount larger than an arbitrarily small constant (measured with a variant of the relative entropy of entanglement), and (ii) a proof that in quantum Merlin-Arthur proof systems, polynomially many provers are not more powerful than a single prover when the verifier is restricted to one-way LOCC operations.

  16. One-way steering of optical fields via dissipation of an atomic reservoir

    NASA Astrophysics Data System (ADS)

    Rao, Shi; Hu, Xiangming; Li, Lingchao; Xu, Jun

    2016-11-01

    Einstein-Podolsky-Rosen (EPR) steering as a form of quantum correlation lies between entanglement and Bell nonlocality and exhibits an inherent asymmetry between two observers. We study EPR steering of two fields, which are generated via four-wave mixing processes and are entangled with each other due to the dissipation of the atomic reservoir. It is shown that the one-way steering happens from one mode to the other for different cavity decay rates and not too small cooperation parameters. Depending on the adiabatic and nonadiabatic conditions, the one-way steering occurs in a different detuning region when the cooperation parameters are relatively small. An increase in the cooperation parameters leads to an increase both in the parameter region and in the degree for the one-way steering. Finally we generalize the present scheme to the cases of the bright and/or collective fields.

  17. Bending self-collimated one-way light by using gyromagnetic photonic crystals

    SciTech Connect

    Li, Qing-Bo; Li, Zhen; Wu, Rui-xin

    2015-12-14

    We theoretically demonstrate that electromagnetic waves can self-collimate and propagate unidirectionally in photonic crystals fabricated using semicylindrical ferrite rods in magnetized states. The parity and time-reversal symmetries of such photonic crystals are broken, resulting in a self-collimated one-way body wave within the photonic crystals. By applying the bias magnetic field in a complex configuration, the self-collimated one-way wave beam can be bent into arbitrary trajectories within the photonic crystal, providing an avenue for controlling wave beams.

  18. Safety valve

    DOEpatents

    Bergman, Ulf C.

    1984-01-01

    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.

  19. Transmission mechanism with parallel transmission systems including one way clutches, one being lockable

    SciTech Connect

    Akashi, T.; Ito, H.; Yamada, S.

    1986-03-18

    A transmission mechanism is described which consists of: an input shaft; an output shaft; a first on-off clutch; a second on-off clutch; a first one way clutch; a second one way clutch; a first gear train having a first reduction gear ratio; a second gear train having a second reduction gear ratio smaller than the first reduction gear ratio; a third gear train having a third reduction gear ratio smaller than the second reduction gear ratio; a fourth gear train having a fourth gear reduction gear ratio smaller than the third reduction gear ratio; a first synchronizer which connects the input shaft and the output shaft; and a second synchronizer which connects the input shaft and the output shaft via a series connection of the second on-off clutch, the second one way clutch, and the second gear train when the second synchronizer is shifted to a first side of a neutral position thereof so as to transmit rotational power from the input shaft to the output shaft in the normal rotational direction and which connects the input shaft and the output shaft via a series connection of the second on-off clutch, the second one way clutch, and the fourth gear train when the second synchronizer is shifted to a second side of the neutral position of the second synchronizer so as to transmit rotational power from the input shaft to the output shaft in the normal rotational direction.

  20. Teaching Principles of One-Way Analysis of Variance Using M&M's Candy

    ERIC Educational Resources Information Center

    Schwartz, Todd A.

    2013-01-01

    I present an active learning classroom exercise illustrating essential principles of one-way analysis of variance (ANOVA) methods. The exercise is easily conducted by the instructor and is instructive (as well as enjoyable) for the students. This is conducive for demonstrating many theoretical and practical issues related to ANOVA and lends itself…

  1. Perceptual shrinkage of a one-way motion path with high-speed motion

    PubMed Central

    Nakajima, Yutaka; Sakaguchi, Yutaka

    2016-01-01

    Back-and-forth motion induces perceptual shrinkage of the motion path, but such shrinkage is hardly perceived for one-way motion. If the shrinkage is caused by temporal averaging of stimulus position around the endpoints, it should also be induced for one-way motion at higher motion speeds. In psychophysical experiments with a high-speed projector, we tested this conjecture for a one-way motion stimulus at various speeds (4–100 deg/s) along a straight path. Results showed that perceptual shrinkage of the motion path was robustly observed in higher-speed motion (faster than 66.7 deg/s). In addition, the amount of the forwards shift at the onset position was larger than that of the backwards shift at the offset position. These results demonstrate that high-speed motion can induce shrinkage, even for a one-way motion path. This can be explained by the view that perceptual position is represented by the integration of the temporal average of instantaneous position and the motion representation. PMID:27464844

  2. [Molecular basis of one-way serological reaction between SINV and XJ-160 virus].

    PubMed

    Wang, Li-hua; Fu, Shi-hong; Yang, Yi-liang; Zhu, Wu-yang; Tang, Qing; Liang, Guo-dong

    2010-05-01

    The purpose of this study is to elucidate the molecular mechanism of one-way serological reaction between XJ-160 virus and SINV by recombinant viruses which exchanged the glycoprotein genes individually or simultaneously. Three recombinant viruses were obtained based on the whole-length infectious cDNA clone of XJ-160 virus. The infectivity and pathogenesis to BHK-21 cells and animals were studied and the gene which controlled this one-way serological reaction phenomenon was searched by MCPENT. The results showed that the E2 glycoprotein was the main factor which influenced the growth rate, plaque morphology and pathogenicity of BHK-21 cells and suckling mice. The results of MCPENT showed that the E2 glycoprotein of SINV played a major role in this one-way serological reaction phenomenon. Our study identified the SINE2 gene was the determined gene for one way serological reaction between XJ-160 virus and SINV, and this research laid the foundation for further analysis of the genomic structure and function of SINV.

  3. More Than One Way to Catch a Fish: Effective Translation of Ocean Science for the Public

    DTIC Science & Technology

    2006-09-01

    translation is one way to make science and technical information more accessible to the public and thereby, improve scientific literacy of many Americans...We present three information translation models that promote scientific and technical literacy . I. INTRODUCTION As more Americans live... literacy ). The organizational structure of the Operations and Education groups (Figure 1) highlights how the two groups interact to provide

  4. A Note on Noncentrality Parameters for Contrast Tests in a One-Way Analysis of Variance

    ERIC Educational Resources Information Center

    Liu, Xiaofeng Steven

    2010-01-01

    The noncentrality parameter for a contrast test in a one-way analysis of variance is based on the dot product of 2 vectors whose geometric meaning in a Euclidian space offers mnemonic hints about its constituents. Additionally, the noncentrality parameters for a set of orthogonal contrasts sum up to the noncentrality parameter for the omnibus…

  5. Quantitative Comparison of Three Standardization Methods Using a One-Way ANOVA for Multiple Mean Comparisons

    ERIC Educational Resources Information Center

    Barrows, Russell D.

    2007-01-01

    A one-way ANOVA experiment is performed to determine whether or not the three standardization methods are statistically different in determining the concentration of the three paraffin analytes. The laboratory exercise asks students to combine the three methods in a single analytical procedure of their own design to determine the concentration of…

  6. 47 CFR 90.490 - One-way paging operations in the private services.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Paging Operations § 90.490 One-way paging... governing the radio service in which a licensee's radio system is authorized, paging operations are... directly from telephone positions in the public switched telephone network. When land stations are...

  7. 47 CFR 90.490 - One-way paging operations in the private services.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Paging Operations § 90.490 One-way paging... governing the radio service in which a licensee's radio system is authorized, paging operations are... directly from telephone positions in the public switched telephone network. When land stations are...

  8. 47 CFR 90.490 - One-way paging operations in the private services.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Paging Operations § 90.490 One-way paging... governing the radio service in which a licensee's radio system is authorized, paging operations are... directly from telephone positions in the public switched telephone network. When land stations are...

  9. Developing English and Spanish Literacy in a One-Way Spanish Immersion Program

    ERIC Educational Resources Information Center

    Hollingsworth, Lindsay Kay

    2013-01-01

    This quantitative, causal-comparative study examined the possible cause and effect relationship between educational programming, specifically one-way Spanish immersion and traditional English-only, and native English-speaking fifth graders' vocabulary and reading comprehension. Archival data was used to examine students' reading achievement as…

  10. A wind-powered one-way bistable medium with parity effects

    NASA Astrophysics Data System (ADS)

    Rosenberger, Tessa; Schattgen, Graham; King-Smith, Matthew; Shrestha, Prakrit; Maxted, Katsuo J.; Lindner, John F.

    2017-02-01

    We describe the design, construction, and dynamics of low-cost mechanical arrays of 3D-printed bistable elements whose shapes interact with wind to couple them one-way. Unlike earlier hydromechanical unidirectional arrays, our aeromechanical one-way arrays are simpler, easier to study, and exhibit a broader range of phenomena. Solitary waves or solitons propagate in one direction at speeds proportional to wind speeds. Periodic boundaries enable solitons to annihilate in pairs in arrays with an even number of elements. Solitons propagate indefinitely in odd arrays that frustrate pairing. Large noise spontaneously creates soliton-antisoliton pairs. Soliton annihilation times increase quadratically with initial separations, as expected for random-walk models of soliton collisions.

  11. A wind-powered one-way bistable medium with parity effects.

    PubMed

    Rosenberger, Tessa; Schattgen, Graham; King-Smith, Matthew; Shrestha, Prakrit; Maxted, Katsuo J; Lindner, John F

    2017-02-01

    We describe the design, construction, and dynamics of low-cost mechanical arrays of 3D-printed bistable elements whose shapes interact with wind to couple them one-way. Unlike earlier hydromechanical unidirectional arrays, our aeromechanical one-way arrays are simpler, easier to study, and exhibit a broader range of phenomena. Solitary waves or solitons propagate in one direction at speeds proportional to wind speeds. Periodic boundaries enable solitons to annihilate in pairs in arrays with an even number of elements. Solitons propagate indefinitely in odd arrays that frustrate pairing. Large noise spontaneously creates soliton-antisoliton pairs. Soliton annihilation times increase quadratically with initial separations, as expected for random-walk models of soliton collisions.

  12. Observation of Genuine One-Way Einstein-Podolsky-Rosen Steering

    NASA Astrophysics Data System (ADS)

    Wollmann, Sabine; Walk, Nathan; Bennet, Adam J.; Wiseman, Howard M.; Pryde, Geoff J.

    2016-04-01

    Within the hierarchy of inseparable quantum correlations, Einstein-Podolsky-Rosen steering is distinguished from both entanglement and Bell nonlocality by its asymmetry—there exist conditions where the steering phenomenon changes from being observable to not observable, simply by exchanging the role of the two measuring parties. While this one-way steering feature has been previously demonstrated for the restricted class of Gaussian measurements, for the general case of positive-operator-valued measures even its theoretical existence has only recently been settled. Here, we prove, and then experimentally observe, the one-way steerability of an experimentally practical class of entangled states in this general setting. As well as its foundational significance, the demonstration of fundamentally asymmetric nonlocality also has practical implications for the distribution of the trust in quantum communication networks.

  13. Experimental realization of Deutsch's algorithm in a one-way quantum computer.

    PubMed

    Tame, M S; Prevedel, R; Paternostro, M; Böhi, P; Kim, M S; Zeilinger, A

    2007-04-06

    We report the first experimental demonstration of an all-optical one-way implementation of Deutsch's quantum algorithm on a four-qubit cluster state. All the possible configurations of a balanced or constant function acting on a two-qubit register are realized within the measurement-based model for quantum computation. The experimental results are in excellent agreement with the theoretical model, therefore demonstrating the successful performance of the algorithm.

  14. A comparison of one-way video and two-way video educational videoteleconferencing

    NASA Astrophysics Data System (ADS)

    Hendrix, Craig L.

    1995-05-01

    The literature reviewed in this study supported the effectiveness of educational videoteleconferencing; however, relatively little research was found comparing the two most interactive types of educational videoteleconferencing systems. An experimental research project was conducted, attempting to determine which educational videoteleconferencing system is more effective. Specifically, this project was designed to answer the following question: Is live two-way video with two-way audio more effective than live one-way video with two-way audio educational videoteleconferencing (EVC)?

  15. Matched Bipartite Digraph Representation of Generalized Dynamical System Formed by One-way Barriers

    NASA Astrophysics Data System (ADS)

    Li, John; Mahoney, John; Mitchell, Kevin; Tom Solomon Collaboration

    2014-03-01

    We studied a dynamical system with stable and unstable manifolds that behave as one-way barriers, instead of separatrices in traditional dynamical system that are two-way barriers. This asymmetry gives rise to a richer dynamical behavior such as the overlapping of basins of attraction. The recently developed Burning Invariant Manifold (BIM) theory took a dynamical system approach to understand front propagation in Advection-Reaction-Diffusion systems, which have BIMs as the one-way barriers. Through numerical simulations under BIM theory, we found that although both unstable and stable BIMs are one-way barriers, unstable BIMs are the ones that we can experimentally observe the fronts converging onto, and the stable BIMs act as the basin boundaries. We further hypothesized a duality relation between the stable and unstable BIMs. Under the duality hypothesis, we developed a mechanism of the behavior of the system by reducing it back to a traditional system based on topology, and we found a simplification of the system by to summarize the topological information into a Matched Bipartite directed graph (MB digraph). This work was supported by the US National Science Foundation under grant PHY-0748828 and NSF Fellowship DGE-0937362.

  16. Measurement of one-way velocity of light and light-year

    NASA Astrophysics Data System (ADS)

    Chen, Shao-Guang

    For space science and astronomy the fundamentality of one-way velocity of light (OWVL) is selfevident. The measurement of OWVL (distance / interval) and the clock synchronization with light-signal transfer make a logical circulation. This means that OWVL could not be directly measured but only come indirectly from astronomical method (Romer's Io eclipse and Bradley's sidereal aberration). Furthermore, the light-year by definitional OWVL and the trigonometry distance with AU are also un-measurable. In this report two methods of clock synchronization to solve this problem were proposed: The arriving-time difference of longitudinal-transverse wave (Ts - Tp) or ordinary-extraordinary light (Te - To) is measured by single clock at one end of a dual-speed transmission-line, the signal transmission-delay (from sending-end time Tx to receiving-end time Tp or To) calculated with wave-speed ratio is: (Tp -Tx) = (Ts -Tp) / ((Vp / Vs) - 1) or: (To -Tx) = (Te - To) / ((Vo / Ve ) - 1), where (Vp / Vs) = (E / k) 1/2 is Yang's / shear elastic-modulus ratio obtained by comparing two strains at same stress, (Vo / Ve) = (ne / no) is extraordinary/ordinary light refractive-index ratio obtained by comparing two deflection-angles. Then, two clocks at transmission-line two ends can be synchronized directly to measure the one-way velocity of light and light-year, which work as one earthquakestation with single clock measures first-shake-time and the distance to epicenter. The readings Na and Nb of two counters Ca and Cb with distance L are transferred into a computer C by two leads with transmission-delay Tac and Tbc respectively. The computer progressing subtraction operation exports steady value: (Nb - Na) = f (Ta - Tb ) + f (Tac - Tbc ), where f is the frequency of light-wave always passing Ca and Cb, Ta and Tb are the count-start time of Ca and Cb respectively. From the transmission-delay possess the spatial translational and rotational invariability, the computer exports steady value

  17. Burning Invariant Manifold Theory and the Bipartite Digraph Representation of Generalized Dynamical System Formed by One-way Barriers

    NASA Astrophysics Data System (ADS)

    Li, John; Mahoney, John; Mitchell, Kevin; Solomon, Tom

    2013-11-01

    The recently developed Burning Invariant Manifold (BIM) theory took a dynamical system approach to understand front propagation in Advection-Reaction-Diffusion systems and successfully predicted both the short-term and asymptotic front behavior by finding the unstable BIMs which act as barriers to front propagation. Unlike separatrices in traditional dynamical system being two-way barriers, the BIMs are one-way barriers. This asymmetry gives rise to a much richer dynamical behavior than traditional dynamical systems. Through numerical simulations, we found that the stable BIMs are the basin boundaries. Based on the properties of BIM theory, we further derived a theory to investigate a dynamical system consists of one-way barriers and the cooperative behavior of these barriers. This theory reveals the global structure of both stable and unstable BIMs by first using a systematic algorithm to convert the flow to a bipartite digraph and then extracting information of the steady states of fronts and corresponding basins of attraction from the digraph. This work was supported by the US National Science Foundation under grant PHY-0748828 and NSF Fellowship DGE-0937362.

  18. One-way acoustic mirror based on anisotropic zero-index media

    SciTech Connect

    Gu, Zhong-ming; Liang, Bin E-mail: jccheng@nju.edu.cn; Yang, Jing; Cheng, Jian-chun E-mail: jccheng@nju.edu.cn; Zou, Xin-ye; Li, Yong; Yang, Jun

    2015-11-23

    We have designed a one-way acoustic mirror comprising anisotropic zero-index media. For acoustic beam incident at a particular angle, the designed structure behaves like a high-efficient mirror that redirects almost all the incident energy into another direction predicted by the Snell's law, while becoming virtually transparent to beams propagating reversely along this output path. Furthermore, the mirror can be tailored to work at arbitrary incident angle by simply adjusting its geometry. Our design, with undirectional reflection functionality and flexible working angle, may offer possibilities in space isolations and have deep implication in various scenarios like ultrasound imaging or noise control.

  19. Seismic Imaging, One-Way Wave Equations, Pseudodifferential Operators, Path Integrals, and all that Jazz

    NASA Astrophysics Data System (ADS)

    Artoun, Ojenie; David-Rus, Diana; Emmett, Matthew; Fishman, Lou; Fital, Sandra; Hogan, Chad; Lim, Jisun; Lushi, Enkeleida; Marinov, Vesselin

    2006-05-01

    In this report we summarize an extension of Fourier analysis for the solution of the wave equation with a non-constant coefficient corresponding to an inhomogeneous medium. The underlying physics of the problem is exploited to link pseudodifferential operators and phase space path integrals to obtain a marching algorithm that incorporates the backward scattering into the evolution of the wave. This allows us to successfully apply single-sweep, one-way marching methods in inherently two-way environments, which was not achieved before through other methods for this problem.

  20. One-way acoustic mirror based on anisotropic zero-index media

    NASA Astrophysics Data System (ADS)

    Gu, Zhong-ming; Liang, Bin; Zou, Xin-ye; Yang, Jing; Li, Yong; Yang, Jun; Cheng, Jian-chun

    2015-11-01

    We have designed a one-way acoustic mirror comprising anisotropic zero-index media. For acoustic beam incident at a particular angle, the designed structure behaves like a high-efficient mirror that redirects almost all the incident energy into another direction predicted by the Snell's law, while becoming virtually transparent to beams propagating reversely along this output path. Furthermore, the mirror can be tailored to work at arbitrary incident angle by simply adjusting its geometry. Our design, with undirectional reflection functionality and flexible working angle, may offer possibilities in space isolations and have deep implication in various scenarios like ultrasound imaging or noise control.

  1. Generating equally weighted test particles from the one-way flux of a drifting Maxwellian

    NASA Astrophysics Data System (ADS)

    Makkonen, T.; Airila, M. I.; Kurki-Suonio, T.

    2015-01-01

    The problem of generating equally weighted test particles from the one way flux of drifting Maxwellian is tackled. This paper extends previous work on the subject by presenting a simple and efficient rejection sampling algorithm together with C++ source files. The properties of the underlying probability distribution function, having the form of a normal distribution times x with positive support, are also disseminated. The method presented in this paper has been successfully used to combine fluid and kinetic models for trace impurity problems in plasma physics.

  2. Observation of broadband unidirectional transmission by fusing the one-way edge states of gyromagnetic photonic crystals.

    PubMed

    Li, Zhen; Wu, Rui-xin; Li, Qing-Bo; Lin, Zhi-fang; Poo, Yin; Liu, Rong-Juan; Li, Zhi-Yuan

    2015-04-20

    We experimentally demonstrate a broadband one-way transmission by merging the operating bands of two types of one-way edge modes that are associated with Bragg scattering and magnetic surface plasmon (MSP) resonance, respectively. By tuning the configuration of gyromagnetic photonic crystals and applied bias magnetic field, the fused bandwidth of unidirectional propagation is up to 2 GHz in microwave frequency range, much larger than either of the individual one-way bandwidth associated with Bragg scattering or MSP resonance. Our scheme for broadband one-way transmission paves the way for the practical applications of one-way transmission.

  3. Multifunctional magneto-metasurface for terahertz one-way transmission and magnetic field sensing.

    PubMed

    Chen, Sai; Fan, Fei; He, Xiaotong; Chen, Meng; Chang, Shengjiang

    2015-11-01

    A magneto-metasurface is demonstrated for one-way transmission of terahertz (THz) waves and magnetic field sensing. Due to the magneto-optical effect and the asymmetric structure of the transmission system, magnetoplasmon mode splitting for forward and backward THz waves and one-way transmission has been observed in this magneto-metasurface. Significantly, the resonance of the magneto-metasurface has been found that can remain at 0.750 THz at a temperature of 218 K, performing as a stable isolator with an isolation of larger than 30 dB within a magnetic field disturbance from 0.23 to 0.35 T. Also, since the resonance of the magneto-metasurface can be tuned by the different external magnetic fields at a temperature that is higher or lower than 218 K, the magneto-metasurface can work as a highly sensitive magnetic field sensor. The sensitivity of this device reaches S=513.05  GHz·T(-1) when T=230  K. This multifunctional magneto-metasurface has broad potential in THz application systems.

  4. Experimental realization of a one-way quantum computer algorithm solving Simon's problem.

    PubMed

    Tame, M S; Bell, B A; Di Franco, C; Wadsworth, W J; Rarity, J G

    2014-11-14

    We report an experimental demonstration of a one-way implementation of a quantum algorithm solving Simon's problem-a black-box period-finding problem that has an exponential gap between the classical and quantum runtime. Using an all-optical setup and modifying the bases of single-qubit measurements on a five-qubit cluster state, key representative functions of the logical two-qubit version's black box can be queried and solved. To the best of our knowledge, this work represents the first experimental realization of the quantum algorithm solving Simon's problem. The experimental results are in excellent agreement with the theoretical model, demonstrating the successful performance of the algorithm. With a view to scaling up to larger numbers of qubits, we analyze the resource requirements for an n-qubit version. This work helps highlight how one-way quantum computing provides a practical route to experimentally investigating the quantum-classical gap in the query complexity model.

  5. One-way absorber for linearly polarized electromagnetic wave utilizing composite metamaterial.

    PubMed

    Zhao, Junming; Sun, Liang; Zhu, Bo; Feng, Yijun

    2015-02-23

    This paper presents the proposal and practical design of a one-way absorber for selective linearly polarized electromagnetic (EM) wave. The EM wave polarization rotation property has been combined with polarization selective absorption utilizing a composite metamaterial slab. The energy of certain linearly polarized EM wave can be absorbed along one particular incident direction, but will be fully transmitted through the opposite direction. For the cross polarized wave, the direction dependent propagation properties are totally reversed. A prototype designed with a total slab thickness of only one-sixth of the operating wavelength is verified through both full-wave simulation and experimental measurement in the microwave regime. It achieves absorption efficiency over 83% along one direction, while transmission efficiency over 83% along the opposite direction for one particular linearly polarized wave. The proposed one-way absorber can be applied in EM devices achieving asymmetric transmission for linearly polarized wave or polarization control. The composite metamaterial that combines different functionalities into one design may provide more potential in metamaterial designs for various applications.

  6. Extending the CLAST sequential rule to one-way ANOVA under group sampling.

    PubMed

    Ximénez, Carmen; Revuelta, Javier

    2007-02-01

    Several studies have demonstrated that the fixed-sample stopping rule (FSR), in which the sample size is determined in advance, is less practical and efficient than are sequential-stopping rules. The composite limited adaptive sequential test (CLAST) is one such sequential-stopping rule. Previous research has shown that CLAST is more efficient in terms of sample size and power than are the FSR and other sequential rules and that it reflects more realistically the practice of experimental psychology researchers. The CLAST rule has been applied only to the t test of mean differences with two matched samples and to the chi-square independence test for twofold contingency tables. The present work extends previous research on the efficiency of CLAST to multiple group statistical tests. Simulation studies were conducted to test the efficiency of the CLAST rule for the one-way ANOVA for fixed effects models. The ANOVA general test and two linear contrasts of multiple comparisons among treatment means are considered. The article also introduces four rules for allocating N observations to J groups under the general null hypothesis and three allocation rules for the linear contrasts. Results show that the CLAST rule is generally more efficient than the FSR in terms of sample size and power for one-way ANOVA tests. However, the allocation rules vary in their optimality and have a differential impact on sample size and power. Thus, selecting an allocation rule depends on the cost of sampling and the intended precision.

  7. Exact Markov chain and approximate diffusion solution for haploid genetic drift with one-way mutation.

    PubMed

    Hössjer, Ola; Tyvand, Peder A; Miloh, Touvia

    2016-02-01

    The classical Kimura solution of the diffusion equation is investigated for a haploid random mating (Wright-Fisher) model, with one-way mutations and initial-value specified by the founder population. The validity of the transient diffusion solution is checked by exact Markov chain computations, using a Jordan decomposition of the transition matrix. The conclusion is that the one-way diffusion model mostly works well, although the rate of convergence depends on the initial allele frequency and the mutation rate. The diffusion approximation is poor for mutation rates so low that the non-fixation boundary is regular. When this happens we perturb the diffusion solution around the non-fixation boundary and obtain a more accurate approximation that takes quasi-fixation of the mutant allele into account. The main application is to quantify how fast a specific genetic variant of the infinite alleles model is lost. We also discuss extensions of the quasi-fixation approach to other models with small mutation rates.

  8. Seasonal Ventilation of the Stratosphere: Robust Diagnostics from One-Way Flux Distributions

    NASA Technical Reports Server (NTRS)

    Orbe, Clara; Holzer, Mark; Polvani, Lorenzo M.; Waugh, Darryn W.; Li, Feng; Oman, Luke D.; Newman, Paul A.

    2014-01-01

    We present an analysis of the seasonally varying ventilation of the stratosphere using one-way flux distributions. Robust transport diagnostics are computed using GEOSCCM subject to fixed present-day climate forcings. From the one-way flux, we determine the mass of the stratosphere that is in transit since entry through the tropical tropopause to its exit back into the troposphere, partitioned according to stratospheric residence time and exit location. The seasonalities of all diagnostics are quantified with respect to the month of year (a) when air enters the stratosphere, (b) when the mass of the stratosphere is partitioned, and (c) when air exits back into the troposphere. We find that the return flux, within 3 months since entry, depends strongly on when entry occurred: (34 +/- 10)% more of the air entering the stratosphere in July leaves poleward of 45 deg N compared to air that enters in January. The month of year when the air mass is partitioned is also found to be important: The stratosphere contains about six times more air of tropical origin during late summer and early fall that will leave poleward of 45 deg within 6 months since entering the stratosphere compared to during late winter to late spring. When the entire mass of the air that entered the stratosphere at the tropics regardless of its residence time is considered, we find that (51 +/- 1)% and (39 +/- 2)% will leave poleward of 10 deg in the Northern Hemisphere (NH) and Southern Hemisphere (SH), respectively.

  9. One-way spatial integration of Navier-Stokes equations: stability of wall-bounded flows

    NASA Astrophysics Data System (ADS)

    Rigas, Georgios; Colonius, Tim; Towne, Aaron; Beyar, Michael

    2016-11-01

    For three-dimensional flows, questions of stability, receptivity, secondary flows, and coherent structures require the solution of large partial-derivative eigenvalue problems. Reduced-order approximations are thus required for engineering prediction since these problems are often computationally intractable or prohibitively expensive. For spatially slowly evolving flows, such as jets and boundary layers, a regularization of the equations of motion sometimes permits a fast spatial marching procedure that results in a huge reduction in computational cost. Recently, a novel one-way spatial marching algorithm has been developed by Towne & Colonius. The new method overcomes the principle flaw observed in Parabolized Stability Equations (PSE), namely the ad hoc regularization that removes upstream propagating modes. The one-way method correctly parabolizes the flow equations based on estimating, in a computationally efficient way, the local spectrum in each cross-stream plane and an efficient spectral filter eliminates modes with upstream group velocity. Results from the application of the method to wall-bounded flows will be presented and compared with predictions from the full linearized compressible Navier-Stokes equations and PSE.

  10. Demonstration of Orbit Determination for the Lunar Reconnaissance Orbiter Using One-Way Laser Ranging Data

    NASA Technical Reports Server (NTRS)

    Bauer, S.; Hussmann, H.; Oberst, J.; Dirkx, D.; Mao, D.; Neumann, G. A.; Mazarico, E.; Torrence, M. H.; McGarry, J. F.; Smith, D. E.; Zuber, M. T.

    2016-01-01

    We used one-way laser ranging data from International Laser Ranging Service (ILRS) ground stations to NASA's Lunar Reconnaissance Orbiter (LRO) for a demonstration of orbit determination. In the one-way setup, the state of LRO and the parameters of the spacecraft and all involved ground station clocks must be estimated simultaneously. This setup introduces many correlated parameters that are resolved by using a priori constraints. More over the observation data coverage and errors accumulating from the dynamical and the clock modeling limit the maximum arc length. The objective of this paper is to investigate the effect of the arc length, the dynamical and modeling accuracy and the observation data coverage on the accuracy of the results. We analyzed multiple arcs using lengths of 2 and 7 days during a one-week period in Science Mission phase 02 (SM02,November2010) and compared the trajectories, the post-fit measurement residuals and the estimated clock parameters. We further incorporated simultaneous passes from multiple stations within the observation data to investigate the expected improvement in positioning. The estimated trajectories were compared to the nominal LRO trajectory and the clock parameters (offset, rate and aging) to the results found in the literature. Arcs estimated with one-way ranging data had differences of 5-30 m compared to the nominal LRO trajectory. While the estimated LRO clock rates agreed closely with the a priori constraints, the aging parameters absorbed clock modeling errors with increasing clock arc length. Because of high correlations between the different ground station clocks and due to limited clock modeling accuracy, their differences only agreed at the order of magnitude with the literature. We found that the incorporation of simultaneous passes requires improved modeling in particular to enable the expected improvement in positioning. We found that gaps in the observation data coverage over 12h (approximately equals 6

  11. Demonstration of orbit determination for the Lunar Reconnaissance Orbiter using one-way laser ranging data

    NASA Astrophysics Data System (ADS)

    Bauer, S.; Hussmann, H.; Oberst, J.; Dirkx, D.; Mao, D.; Neumann, G. A.; Mazarico, E.; Torrence, M. H.; McGarry, J. F.; Smith, D. E.; Zuber, M. T.

    2016-09-01

    We used one-way laser ranging data from International Laser Ranging Service (ILRS) ground stations to NASA's Lunar Reconnaissance Orbiter (LRO) for a demonstration of orbit determination. In the one-way setup, the state of LRO and the parameters of the spacecraft and all involved ground station clocks must be estimated simultaneously. This setup introduces many correlated parameters that are resolved by using a priori constraints. Moreover the observation data coverage and errors accumulating from the dynamical and the clock modeling limit the maximum arc length. The objective of this paper is to investigate the effect of the arc length, the dynamical and modeling accuracy and the observation data coverage on the accuracy of the results. We analyzed multiple arcs using lengths of 2 and 7 days during a one-week period in Science Mission phase 02 (SM02, November 2010) and compared the trajectories, the post-fit measurement residuals and the estimated clock parameters. We further incorporated simultaneous passes from multiple stations within the observation data to investigate the expected improvement in positioning. The estimated trajectories were compared to the nominal LRO trajectory and the clock parameters (offset, rate and aging) to the results found in the literature. Arcs estimated with one-way ranging data had differences of 5-30 m compared to the nominal LRO trajectory. While the estimated LRO clock rates agreed closely with the a priori constraints, the aging parameters absorbed clock modeling errors with increasing clock arc length. Because of high correlations between the different ground station clocks and due to limited clock modeling accuracy, their differences only agreed at the order of magnitude with the literature. We found that the incorporation of simultaneous passes requires improved modeling in particular to enable the expected improvement in positioning. We found that gaps in the observation data coverage over 12 h (≈6 successive LRO orbits

  12. Transport properties of MOPhC/metal one-way waveguide

    SciTech Connect

    Eyderman, Sergey; Kuzmiak, Vladimir

    2011-10-03

    We have demonstrated numerically that the interface between metal and uniformly magnetized 2D photonic crystal(PC) fabricated from a transparent dielectric magneto-optic(MO) material possesses a one-way frequency range where only a forward propagating surface plasmon polariton mode is allowed to propagate. By using a simple theoretical model we have shown that nonreciprocity is introduced by the MO properties of the PC. Transport properties of the structures within this frequency range have been investigated by FDTD method which enables to calculating propagation of EM waves through media with full tensorial MO permittivity. We found that in the presence of a time-dependent external magnetic field interesting features associated with the redistribution of the EM field appear.

  13. Acoustic one-way metasurfaces: Asymmetric Phase Modulation of Sound by Subwavelength Layer

    PubMed Central

    Jiang, Xue; Liang, Bin; Zou, Xin-ye; Yang, Jing; Yin, Lei-lei; Yang, Jun; Cheng, Jian-chun

    2016-01-01

    We theoretically design and numerically demonstrate an acoustic one-way metasurface, which is a planar and acoustically subwavelength layer behaving like a nearly-reflectionless surface with arbitrary wave-steering capability for incident wave impinging on one side, while virtually blocking the reversed wave. The underlying mechanism is based on an asymmetric phase modulation by coupling a phase array and a near-zero-index medium. We exemplify a metastructure-based implementation by combining the hybrid metastuctures and labyrinthine structures. Moreover, the performance of the proposed implementation is demonstrated via three distinct phenomena of anomalous refraction, wave splitting and conversion of propagation wave to surface wave. Our findings may offer more possibilities for sound manipulation and improve the application potential of acoustic artificial devices in situations such as ultrasonic imaging and therapy. PMID:27305973

  14. One-way rotation of a molecule-rotor driven by a shot noise.

    PubMed

    Echeverria, Jorge; Monturet, Serge; Joachim, Christian

    2014-03-07

    The shot noise of a tunneling current passing through a molecule-motor can sustain a one-way rotation when populating the molecular excited states by tunneling inelastic excitations. We demonstrate that a ratchet-like ground state rotation potential energy curve is not necessary for the rotation to occur. A relative shift in energy difference between the maxima of this ground state and the minima of the excited states is the necessary condition to get to a unidirectional rotation. The rotor speed of rotation and its rotation direction are both controlled by this shift, indicating the necessity of a careful design of both the ground and excited states of the next generation of molecule-motors to be able to generate a motive power at the nanoscale.

  15. One-way quantum key distribution: Simple upper bound on the secret key rate

    SciTech Connect

    Moroder, Tobias; Luetkenhaus, Norbert; Curty, Marcos

    2006-11-15

    We present a simple method to obtain an upper bound on the achievable secret key rate in quantum key distribution (QKD) protocols that use only unidirectional classical communication during the public-discussion phase. This method is based on a necessary precondition for one-way secret key distillation; the legitimate users need to prove that there exists no quantum state having a symmetric extension that is compatible with the available measurements results. The main advantage of the obtained upper bound is that it can be formulated as a semidefinite program, which can be efficiently solved. We illustrate our results by analyzing two well-known qubit-based QKD protocols: the four-state protocol and the six-state protocol.

  16. Gencrypt: one-way cryptographic hashes to detect overlapping individuals across samples

    PubMed Central

    Turchin, Michael C.; Hirschhorn, Joel N.

    2012-01-01

    Summary: Meta-analysis across genome-wide association studies is a common approach for discovering genetic associations. However, in some meta-analysis efforts, individual-level data cannot be broadly shared by study investigators due to privacy and Institutional Review Board concerns. In such cases, researchers cannot confirm that each study represents a unique group of people, leading to potentially inflated test statistics and false positives. To resolve this problem, we created a software tool, Gencrypt, which utilizes a security protocol known as one-way cryptographic hashes to allow overlapping participants to be identified without sharing individual-level data. Availability: Gencrypt is freely available under the GNU general public license v3 at http://www.broadinstitute.org/software/gencrypt/ Contact: joelh@broadinstitute.org Supplementary information: Supplementary data are available at Bioinformatics online. PMID:22302573

  17. A one-way shooting algorithm for transition path sampling of asymmetric barriers.

    PubMed

    Brotzakis, Z Faidon; Bolhuis, Peter G

    2016-10-28

    We present a novel transition path sampling shooting algorithm for the efficient sampling of complex (biomolecular) activated processes with asymmetric free energy barriers. The method employs a fictitious potential that biases the shooting point toward the transition state. The method is similar in spirit to the aimless shooting technique by Peters and Trout [J. Chem. Phys. 125, 054108 (2006)], but is targeted for use with the one-way shooting approach, which has been shown to be more effective than two-way shooting algorithms in systems dominated by diffusive dynamics. We illustrate the method on a 2D Langevin toy model, the association of two peptides and the initial step in dissociation of a β-lactoglobulin dimer. In all cases we show a significant increase in efficiency.

  18. Optimal sample size allocation for Welch's test in one-way heteroscedastic ANOVA.

    PubMed

    Shieh, Gwowen; Jan, Show-Li

    2015-06-01

    The determination of an adequate sample size is a vital aspect in the planning stage of research studies. A prudent strategy should incorporate all of the critical factors and cost considerations into sample size calculations. This study concerns the allocation schemes of group sizes for Welch's test in a one-way heteroscedastic ANOVA. Optimal allocation approaches are presented for minimizing the total cost while maintaining adequate power and for maximizing power performance for a fixed cost. The commonly recommended ratio of sample sizes is proportional to the ratio of the population standard deviations or the ratio of the population standard deviations divided by the square root of the ratio of the unit sampling costs. Detailed numerical investigations have shown that these usual allocation methods generally do not give the optimal solution. The suggested procedures are illustrated using an example of the cost-efficiency evaluation in multidisciplinary pain centers.

  19. Acoustic one-way metasurfaces: Asymmetric Phase Modulation of Sound by Subwavelength Layer

    NASA Astrophysics Data System (ADS)

    Jiang, Xue; Liang, Bin; Zou, Xin-Ye; Yang, Jing; Yin, Lei-Lei; Yang, Jun; Cheng, Jian-Chun

    2016-06-01

    We theoretically design and numerically demonstrate an acoustic one-way metasurface, which is a planar and acoustically subwavelength layer behaving like a nearly-reflectionless surface with arbitrary wave-steering capability for incident wave impinging on one side, while virtually blocking the reversed wave. The underlying mechanism is based on an asymmetric phase modulation by coupling a phase array and a near-zero-index medium. We exemplify a metastructure-based implementation by combining the hybrid metastuctures and labyrinthine structures. Moreover, the performance of the proposed implementation is demonstrated via three distinct phenomena of anomalous refraction, wave splitting and conversion of propagation wave to surface wave. Our findings may offer more possibilities for sound manipulation and improve the application potential of acoustic artificial devices in situations such as ultrasonic imaging and therapy.

  20. An experiment to measure the one-way velocity of propagation of electromagnetic radiation

    NASA Technical Reports Server (NTRS)

    Kolen, P.; Torr, D. G.

    1982-01-01

    An experiment involving commercially available instrumentation to measure the velocity of the earth with respect to absolute space is described. The experiment involves the measurement of the one-way propagation velocity of electromagnetic radiation down a high-quality coaxial cable. It is demonstrated that the experiment is both physically meaningful and exceedingly simple in concept and in implementation. It is shown that with currently available commercial equipment one might expect to detect a threshold value for the component of velocity of the earth's motion with respect to absolute space in the equatorial plane of approximately 10 km/s, which greatly exceeds the velocity resolution required to detect the motion of the solar system with respect to the center of the galaxy.

  1. A one-way shooting algorithm for transition path sampling of asymmetric barriers

    NASA Astrophysics Data System (ADS)

    Brotzakis, Z. Faidon; Bolhuis, Peter G.

    2016-10-01

    We present a novel transition path sampling shooting algorithm for the efficient sampling of complex (biomolecular) activated processes with asymmetric free energy barriers. The method employs a fictitious potential that biases the shooting point toward the transition state. The method is similar in spirit to the aimless shooting technique by Peters and Trout [J. Chem. Phys. 125, 054108 (2006)], but is targeted for use with the one-way shooting approach, which has been shown to be more effective than two-way shooting algorithms in systems dominated by diffusive dynamics. We illustrate the method on a 2D Langevin toy model, the association of two peptides and the initial step in dissociation of a β-lactoglobulin dimer. In all cases we show a significant increase in efficiency.

  2. One-way Tamm plasmon polaritons at the interface between magnetophotonic crystals and conducting metal oxides

    NASA Astrophysics Data System (ADS)

    Dong, Hui Yuan; Wang, Jin; Cui, Tie Jun

    2013-01-01

    We demonstrate theoretically the existence of one-way Tamm plasmon polaritons on the interface between magnetophotonic crystals and conducting metal oxides. In contrast to conventional surface plasmon-polaritons (SPPs), Tamm plasmon polaritons (TPPs) occur at frequencies above the bulk plasma frequency of the conducting materials, provided that the dispersion curves of such surface modes lie outside the light cone for the conducting oxides and simultaneously fall into the photonic band gap of the magnetophotonic crystal. The nonreciprocal properties of TPPs are caused by violation of the periodicity and time-reversal symmetry in the structure. Calculations on the field distribution and transmission spectra through the structure are employed to confirm the theoretical results, which could potentially impact on a broad range of SPP-related phenomena in applications.

  3. Analysis of one-way laser ranging data to LRO, time transfer and clock characterization

    NASA Astrophysics Data System (ADS)

    Bauer, S.; Hussmann, H.; Oberst, J.; Dirkx, D.; Mao, D.; Neumann, G. A.; Mazarico, E.; Torrence, M. H.; McGarry, J. F.; Smith, D. E.; Zuber, M. T.

    2017-02-01

    We processed and analyzed one-way laser ranging data from International Laser Ranging Service ground stations to NASA's Lunar Reconnaissance Orbiter (LRO), obtained from June 13, 2009 until September 30, 2014. We pair and analyze the one-way range observables from station laser fire and spacecraft laser arrival times by using nominal LRO orbit models based on the GRAIL gravity field. We apply corrections for instrument range walk, as well as for atmospheric and relativistic effects. In total we derived a tracking data volume of ≈ 3000 hours featuring 64 million Full Rate and 1.5 million Normal Point observations. From a statistical analysis of the dataset we evaluate the experiment and the ground station performance. We observe a laser ranging measurement precision of 12.3 cm in case of the Full Rate data which surpasses the LOLA timestamp precision of 15 cm. The averaging to Normal Point data further reduces the measurement precision to 5.6 cm. We characterized the LRO clock with fits throughout the mission time and estimated the rate to 6.9 × 10-8, the aging to 1.6 × 10-12/day and the change of aging to 2.3 × 10-14 /day2over all mission phases. The fits also provide referencing of onboard time to the TDB time scale at a precision of 166 ns over two and 256 ns over all mission phases, representing ground to space time transfer. Furthermore we measure ground station clock differences from the fits as well as from simultaneous passes which we use for ground to ground time transfer from common view observations. We observed relative offsets ranging from 33 to 560 ns and relative rates ranging from 2 × 10-13 to 6 × 10-12 between the ground station clocks during selected mission phases. We study the results from the different methods and discuss their applicability for time transfer.

  4. Non-reciprocity and topology in optics: one-way road for light via surface magnon polariton.

    PubMed

    Ochiai, Tetsuyuki

    2015-02-01

    We show how non-reciprocity and topology are used to construct an optical one-way waveguide in the Voigt geometry. First, we present a traditional approach of the one-way waveguide of light using surface polaritons under a static magnetic field. Second, we explain a recent discovery of a topological approach using photonic crystals with the magneto-optical coupling. Third, we present a combination of the two approaches, toward a broadband one-way waveguide in the microwave range.

  5. Heart valve surgery - discharge

    MedlinePlus

    ... surgery - minimally invasive Aortic valve surgery - open Bicuspid aortic valve Endocarditis Heart valve surgery Mitral valve prolapse Mitral valve surgery - minimally invasive Mitral valve surgery - open Pulmonary valve stenosis Smoking - tips on how to quit Patient Instructions ...

  6. Analysis of One-Way Laser Ranging Data to LRO, Time Transfer and Clock Characterization

    NASA Technical Reports Server (NTRS)

    Bauer, S.; Hussmann, H.; Oberst, J.; Dirkx, D.; Mao, D.; Neumann, G. A.; Mazarico, E.; Torrence, M. H.; McGarry, J. F.; Smith, D. E.; Zuber, M. T.

    2016-01-01

    We processed and analyzed one-way laser ranging data from International Laser Ranging Service ground stations to NASA's Lunar Reconnaissance Orbiter (LRO), obtained from June 13, 2009 until September 30, 2014. We pair and analyze the one-way range observables from station laser fire and spacecraft laser arrival times by using nominal LRO orbit models based on the GRAIL gravity field. We apply corrections for instrument range walk, as well as for atmospheric and relativistic effects. In total we derived a tracking data volume of approximately 3000 hours featuring 64 million Full Rate and 1.5 million Normal Point observations. From a statistical analysis of the dataset we evaluate the experiment and the ground station performance. We observe a laser ranging measurement precision of 12.3 centimeters in case of the Full Rate data which surpasses the LOLA (Lunar Orbiting Laser Altimeter) timestamp precision of 15 centimeters. The averaging to Normal Point data further reduces the measurement precision to 5.6 centimeters. We characterized the LRO clock with fits throughout the mission time and estimated the rate to 6.9 times10 (sup -8), the aging to 1.6 times 10 (sup -12) per day and the change of aging to 2.3 times 10 (sup -14) per day squared over all mission phases. The fits also provide referencing of onboard time to the TDB (Barycentric Dynamical Time) time scale at a precision of 166 nanoseconds over two and 256 nanoseconds over all mission phases, representing ground to space time transfer. Furthermore we measure ground station clock differences from the fits as well as from simultaneous passes which we use for ground to ground time transfer from common view observations. We observed relative offsets ranging from 33 to 560 nanoseconds and relative rates ranging from 2 times 10 (sup -13) to 6 times 10 (sup -12) between the ground station clocks during selected mission phases. We study the results from the different methods and discuss their applicability for time

  7. Checking Questionable Entry of Personally Identifiable Information Encrypted by One-Way Hash Transformation

    PubMed Central

    Chen, Xianlai; Fann, Yang C; McAuliffe, Matthew; Vismer, David

    2017-01-01

    Background As one of the several effective solutions for personal privacy protection, a global unique identifier (GUID) is linked with hash codes that are generated from combinations of personally identifiable information (PII) by a one-way hash algorithm. On the GUID server, no PII is permitted to be stored, and only GUID and hash codes are allowed. The quality of PII entry is critical to the GUID system. Objective The goal of our study was to explore a method of checking questionable entry of PII in this context without using or sending any portion of PII while registering a subject. Methods According to the principle of GUID system, all possible combination patterns of PII fields were analyzed and used to generate hash codes, which were stored on the GUID server. Based on the matching rules of the GUID system, an error-checking algorithm was developed using set theory to check PII entry errors. We selected 200,000 simulated individuals with randomly-planted errors to evaluate the proposed algorithm. These errors were placed in the required PII fields or optional PII fields. The performance of the proposed algorithm was also tested in the registering system of study subjects. Results There are 127,700 error-planted subjects, of which 114,464 (89.64%) can still be identified as the previous one and remaining 13,236 (10.36%, 13,236/127,700) are discriminated as new subjects. As expected, 100% of nonidentified subjects had errors within the required PII fields. The possibility that a subject is identified is related to the count and the type of incorrect PII field. For all identified subjects, their errors can be found by the proposed algorithm. The scope of questionable PII fields is also associated with the count and the type of the incorrect PII field. The best situation is to precisely find the exact incorrect PII fields, and the worst situation is to shrink the questionable scope only to a set of 13 PII fields. In the application, the proposed algorithm can

  8. One-way approximation for the simulation of weak shock wave propagation in atmospheric flows.

    PubMed

    Gallin, Louis-Jonardan; Rénier, Mathieu; Gaudard, Eric; Farges, Thomas; Marchiano, Régis; Coulouvrat, François

    2014-05-01

    A numerical scheme is developed to simulate the propagation of weak acoustic shock waves in the atmosphere with no absorption. It generalizes the method previously developed for a heterogeneous medium [Dagrau, Rénier, Marchiano, and Coulouvrat, J. Acoust. Soc. Am. 130, 20-32 (2011)] to the case of a moving medium. It is based on an approximate scalar wave equation for potential, rewritten in a moving time frame, and separated into three parts: (i) the linear wave equation in a homogeneous and quiescent medium, (ii) the effects of atmospheric winds and of density and speed of sound heterogeneities, and (iii) nonlinearities. Each effect is then solved separately by an adapted method: angular spectrum for the wave equation, finite differences for the flow and heterogeneity corrections, and analytical method in time domain for nonlinearities. To keep a one-way formulation, only forward propagating waves are kept in the angular spectrum part, while a wide-angle parabolic approximation is performed on the correction terms. The numerical process is validated in the case of guided modal propagation with a shear flow. It is then applied to the case of blast wave propagation within a boundary layer flow over a flat and rigid ground.

  9. Integratable quarter-wave plates enable one-way angular momentum conversion.

    PubMed

    Liang, Yao; Zhang, Fengchun; Gu, Jiahua; Huang, Xu Guang; Liu, Songhao

    2016-04-22

    Nanophotonic waveguides are the building blocks of integrated photonics. To date, while quarter-wave plates (QWPs) are widely used as common components for a wide range of applications in free space, there are almost no reports of Integratable QWPs being able to manipulate the angular momentum (AM) of photons inside nanophotonic waveguides. Here, we demonstrate two kinds of Integratable QWPs respectively based on the concept of abrupt phase change and birefringence effect. The orientation of the equivalent optical axis of an Integratable QWP is designable. Remarkably, a combination of two integratable QWPs with different equivalent optical axes leads to an integrated system that performances one-way AM conversion. Moreover, this system can be used as a point source that can excite different patterns on a metal surface via directional excitation of surface plasmon polaritons (SPP). These results allow for the control of AM of light in nanophotonic waveguides, which are crucial for various applications with limited physical space, such as on-chip bio-sensing and integrated quantum information processing.

  10. Integratable quarter-wave plates enable one-way angular momentum conversion

    PubMed Central

    Liang, Yao; Zhang, Fengchun; Gu, Jiahua; Huang, Xu Guang; Liu, Songhao

    2016-01-01

    Nanophotonic waveguides are the building blocks of integrated photonics. To date, while quarter-wave plates (QWPs) are widely used as common components for a wide range of applications in free space, there are almost no reports of Integratable QWPs being able to manipulate the angular momentum (AM) of photons inside nanophotonic waveguides. Here, we demonstrate two kinds of Integratable QWPs respectively based on the concept of abrupt phase change and birefringence effect. The orientation of the equivalent optical axis of an Integratable QWP is designable. Remarkably, a combination of two integratable QWPs with different equivalent optical axes leads to an integrated system that performances one-way AM conversion. Moreover, this system can be used as a point source that can excite different patterns on a metal surface via directional excitation of surface plasmon polaritons (SPP). These results allow for the control of AM of light in nanophotonic waveguides, which are crucial for various applications with limited physical space, such as on-chip bio-sensing and integrated quantum information processing. PMID:27102332

  11. Effects of hippocampal stimulation on retention and extinction of one way active avoidance response in cats.

    PubMed

    Gralewicz, K; Gralewicz, S

    1984-01-01

    We found previously that hippocampal stimulation (HiSt) at 20 cps, 100 mikroA, applied jointly with a tone (500 Hz) CS in the course of retention test, improved the performance and retarded the extinction of one way active avoidance response (AAR) in cats. During this test failures to perform the AAR were not punished in all but two trials it the beginning of each session. The first experiment of the present studies demonstrated that - (i) the AAR facilitating the effect of HiSt might be prevented by m all electrolytic lesions made around the tips of the stimulating electrodes, (ii) large lesions of the hippocampus exerted little effect on the AAR acquisition, but the response was extinguished faster during the retention test. In the second experiment two response prevention trials (non-reinforced presentations of the CS with no possibility to make the AAR) were run at the beginning of each session after the end of training. In these conditions the HiSt resulted in a faster extinction of the AAR as compared with implanted unstimulated animals. Large lesions of the hippocampus had no effect on the extinction rate. We conclude that the facilitation of retrieval from memory may be responsible for the effects of HiSt on conditioned behavior.

  12. Building of one-way Hadamard gate for squeezed coherent states

    NASA Astrophysics Data System (ADS)

    Podoshvedov, Sergey A.

    2013-01-01

    We present an optical scheme to conditionally generate even or odd squeezed superpositions of coherent states (SSCSs). The optical setup consists of an unbalanced beam splitter whose transmittance tends to unity, and additional balanced beam splitters and photodetectors in auxiliary modes. Squeezed coherent states with different amplitudes are the input states in the optical scheme. The single-qubit operations are probabilistic and employ two- and three-photon subtractions from initial beams as the driving force. Generation of the even or odd SSCSs is observed in a wide diapason of values of used parameters. We consider a possibility to realize a one-way Hadamard gate for the squeezed coherent states when the base states are transformed into superposition states. States approximating the output states of a Hadamard gate with high fidelity can be realized by imposing restrictions on the values of used parameters. Higher-order subtractions from input beams are necessary to generate the SSCSs with larger amplitudes and higher fidelities. The problem is resolved in a Wigner representation to take into account imperfections of the optical devices.

  13. Two-factor authentication system based on optical interference and one-way hash function

    NASA Astrophysics Data System (ADS)

    He, Wenqi; Peng, Xiang; Meng, Xiangfeng; Liu, Xiaoli

    2012-10-01

    We present a two-factor authentication method to verify the personal identification who tries to access an optoelectronic system. This method is based on the optical interference principle and the traditional one-way Hash function (e.g. MD5). The authentication process is straightforward, the phase key and the password-controlled phase lock of one user are loading on two Spatial Light Modulators (SLMs) in advance, by which two coherent beams are modulated and then interference with each other at the output plane leading to an output image. By comparing the output image with all the standard certification images in the database, the system can thus verify the user's identity. However, the system designing process involves an iterative Modified Phase Retrieval Algorithm (MPRA). For an uthorized user, a phase lock is first created based on a "Digital Fingerprint (DF)", which is the result of a Hash function on a preselected user password. The corresponding phase key can then be determined by use of the phase lock and a designated standard certification image. Note that the encode/design process can only be realized by digital means while the authentication process could be achieved digitally or optically. Computer simulations were also given to validate the proposed approach.

  14. Evidence-based practice guidelines--one way to enhance clinical practice.

    PubMed

    Bailes, Barbara K

    2002-06-01

    Abdominoplasty and liposuction guidelines are just two of the guidelines that can be accessed and used to enhance patient care. Guidelines also can be used to increase your knowledge about many other health care topics. The NGC has approved guidelines for managing chronic pain, as well as guidelines on chronic diseases (e.g., diabetes mellitus, hypertension, chronic obstructive pulmonary disease). Many patients have chronic diseases, and you or your family members also may be affected by chronic disorders. These guidelines provide you with a quick overview of evidence-based treatment protocols. These guidelines are not a panacea for evidence-based practice, but using them is one way that perioperative nurses can enhance their clinical skills. Though not everyone has personal Internet access, most health care facilities do or can make access a reality. Other options include medical or public libraries. Then one simply has to access the NGC web site and join other professionals in improving the quality and timeliness of patient care.

  15. Analysis of the characteristics of GRACE dual one-way ranging system

    NASA Astrophysics Data System (ADS)

    Ko, Ung Dai

    The motivation for this research was an improvement of the quality of the Earth's gravity solutions from the GRACE mission data through an instrument-level study. The objective was a better understanding of the characteristics and sources of the high-frequency noise in the range of (0.02 ˜ 0.1 Hz) in the dual one-way ranging (DOWR) and its effect on the gravity solution. For this purpose, the mathematical model of the DOWR observation was derived and the Allan variance was computed to establish an upper bound on the level of frequency instability of the ultra-stable oscillators (USO) to determine their contribution to the high-frequency noise. Because they are dominated by the high-frequency noise, the postfit residuals of the time derivative of the DOWR ranges were also examined to evaluate the contributions of various other factors such as system noise from the microwave signal receiver, external influences, and internal influences. The results indicate that the system noise is the dominant source of the excessive high-frequency noise. As one method of mitigation, a tighter bandwidth filter was applied to the DOWR processing, resulting in modest improvements in gravity solutions.

  16. Check valve

    DOEpatents

    Upton, H.A.; Garcia, P.

    1999-08-24

    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.

  17. Check valve

    DOEpatents

    Upton, Hubert Allen; Garcia, Pablo

    1999-08-24

    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.

  18. Manipulating one-way space wave and its refraction by time-reversal and parity symmetry breaking

    PubMed Central

    Poo, Yin; He, Cheng; Xiao, Chao; Lu, Ming-Hui; Wu, Rui-Xin; Chen, Yan-Feng

    2016-01-01

    One-way transmission and negative refraction are the exotic wave properties founded in photonic crystals which attract a great attention due to their promising applications in photonic devices. How to integrate such two phenomena in one material or device is interesting and valuable. In this work, we theoretically and experimentally demonstrate that one-way electromagnetic space wave can be realized by means of two-dimensional magnetic photonic crystals. Simultaneously breaking the time-reversal and parity symmetries of the magnetic photonic crystals designed, we observe oblique incident space wave propagating one-way in the magnetic photonic crystals with positive or negative refraction occurring at interfaces, which can be manipulated upon the incident angle and operating frequency. Our work may offer a potential platform to realize some exotic photoelectronic and microwave devices such as one-way imaging and one-way cloaking. PMID:27387438

  19. Manipulating one-way space wave and its refraction by time-reversal and parity symmetry breaking.

    PubMed

    Poo, Yin; He, Cheng; Xiao, Chao; Lu, Ming-Hui; Wu, Rui-Xin; Chen, Yan-Feng

    2016-07-08

    One-way transmission and negative refraction are the exotic wave properties founded in photonic crystals which attract a great attention due to their promising applications in photonic devices. How to integrate such two phenomena in one material or device is interesting and valuable. In this work, we theoretically and experimentally demonstrate that one-way electromagnetic space wave can be realized by means of two-dimensional magnetic photonic crystals. Simultaneously breaking the time-reversal and parity symmetries of the magnetic photonic crystals designed, we observe oblique incident space wave propagating one-way in the magnetic photonic crystals with positive or negative refraction occurring at interfaces, which can be manipulated upon the incident angle and operating frequency. Our work may offer a potential platform to realize some exotic photoelectronic and microwave devices such as one-way imaging and one-way cloaking.

  20. Manipulating one-way space wave and its refraction by time-reversal and parity symmetry breaking

    NASA Astrophysics Data System (ADS)

    Poo, Yin; He, Cheng; Xiao, Chao; Lu, Ming-Hui; Wu, Rui-Xin; Chen, Yan-Feng

    2016-07-01

    One-way transmission and negative refraction are the exotic wave properties founded in photonic crystals which attract a great attention due to their promising applications in photonic devices. How to integrate such two phenomena in one material or device is interesting and valuable. In this work, we theoretically and experimentally demonstrate that one-way electromagnetic space wave can be realized by means of two-dimensional magnetic photonic crystals. Simultaneously breaking the time-reversal and parity symmetries of the magnetic photonic crystals designed, we observe oblique incident space wave propagating one-way in the magnetic photonic crystals with positive or negative refraction occurring at interfaces, which can be manipulated upon the incident angle and operating frequency. Our work may offer a potential platform to realize some exotic photoelectronic and microwave devices such as one-way imaging and one-way cloaking.

  1. Valve Disease

    MedlinePlus

    ... valves in the heart: tricuspid, pulmonary, mitral, and aortic. Two types of problems can disrupt blood flow though the valves: regurgitation or stenosis. Regurgitation is also called insufficiency or incompetence. Regurgitation ...

  2. Fast valve

    DOEpatents

    Van Dyke, W.J.

    1992-04-07

    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.

  3. Fast valve

    DOEpatents

    Van Dyke, William J.

    1992-01-01

    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. COBE navigation with one-way return-link Doppler in the post-helium-venting phase

    NASA Astrophysics Data System (ADS)

    Dunham, Joan; Nemesure, M.; Samii, M. V.; Maher, M.; Teles, Jerome; Jackson, J.

    1991-12-01

    The results of a navigation experiment with one way return link Doppler tracking measurements for operational orbit determination of the Cosmic Background Explorer (COBE) spacecraft are presented. The frequency of the tracking signal for the one way measurements was stabilized with an Ultrastable Oscillator (USO), and the signal was relayed by the Tracking and Data Relay Satellite System (TDRSS). The study achieved three objectives: space qualification of TDRSS noncoherent one way return link Doppler tracking; determination of flight performance of the USO coupled to the second generation TDRSS compatible user transponder; and verification of algorithms for navigation using actual one way tracking data. Orbit determination and the inflight USO performance evaluation results are presented.

  5. Depressurization valve

    DOEpatents

    Skoda, G.I.

    1989-03-28

    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.

  6. Selective, Spontaneous One-Way Oil-Transport Fabrics and Their Novel Use for Gauging Liquid Surface Tension.

    PubMed

    Wang, Hongxia; Zhou, Hua; Yang, Weidong; Zhao, Yan; Fang, Jian; Lin, Tong

    2015-10-21

    Thin porous materials that can spontaneously transport oil fluids just in a single direction have great potential for making energy-saving functional membranes. However, there is little data for the preparation and functionalities of this smart material. Here, we report a novel method to prepare one-way oil-transport fabrics and their application in detecting liquid surface tension. This functional fabric was prepared by a two-step coating process to apply flowerlike ZnO nanorods, fluorinated decyl polyhedral oligomeric silsesquioxanes, and hydrolyzed fluorinated alkylsilane on a fabric substrate. Upon one-sided UV irradiation, the coated fabric shows a one-way transport feature that allows oil fluid transport automatically from the unirradiated side to the UV-irradiated surface, but it stops fluid transport in the opposite direction. The fabric still maintains high superhydrophobicity after UV treatment. The one-way fluid transport takes place only for the oil fluids with a specific surface tension value, and the fluid selectivity is dependent on the UV treatment time. Changing the UV irradiation time from 6 to 30 h broadened the one-way transport for fluids with surface tension from around 22.3 mN/m to a range of 22.3-56.7 mN/m. We further proved that this selective one-way oil transport can be used to estimate the surface tension of a liquid simply by observing its transport feature on a series of fabrics with different one-way oil-transport selectivities. To our knowledge, this is the first example to use one-way fluid-transport materials for testing the liquid surface tension. It may open up further theoretical studies and the development of novel fluid sensors.

  7. One-way optical modal transition based on causality in momentum space.

    PubMed

    Yu, Sunkyu; Piao, Xianji; Yoo, KyungWan; Shin, Jonghwa; Park, Namkyoo

    2015-09-21

    The concept of parity-time (PT) symmetry has been used to identify a route toward unidirectional dynamics in optical k-space: imposing asymmetry on the flow of light. Although PT-symmetric potentials have been implemented under the requirement of V(x) = V*(-x), this precondition has only been interpreted within the mathematical framework for the symmetry of Hamiltonians and has not been directly linked to unidirectionality induced by PT symmetry. In this paper, within the context of light-matter interactions, we develop an alternative route toward unidirectionality in k-space by employing the concept of causality. We demonstrate that potentials with real and causal momentum spectra produce unidirectional transitions of optical modes inside the k-continuum, which corresponds to an exceptional point on the degree of PT symmetry. Our analysis reveals a critical link between non-Hermitian problems and spectral theory and also enables multi-dimensional designer manipulation of optical modes, in contrast to the one-dimensional approach that used a Schrödinger-like equation in previous PT-symmetric optics.

  8. More than one way to be happy: a typology of marital happiness.

    PubMed

    Rauer, Amy; Volling, Brenda

    2013-09-01

    This study utilized observational and self-report data from 57 happily married couples to explore assumptions regarding marital happiness. Suggesting that happily married couples are not a homogeneous group, cluster analyses revealed the existence of three types of couples based on their observed behaviors in a problem-solving task: (1) mutually engaged couples (characterized by both spouses' higher negative and positive problem-solving); (2) mutually supportive couples (characterized by both spouses' higher positivity and support); and (3) wife compensation couples (characterized by high wife positivity). Although couples in all three clusters were equally happy with and committed to their marriages, these clusters were differentially associated with spouses' evaluations of their marriage. Spouses in the mutually supportive cluster reported greater intimacy and maintenance and less conflict and ambivalence, although this was more consistently the case in comparison to the wife compensation cluster, as opposed to the mutually engaged cluster. The implications of these typologies are discussed as they pertain to efforts on the part of both practitioners to promote marital happiness and repair marital relations when couples are faced with difficulties.

  9. Problem: Heart Valve Stenosis

    MedlinePlus

    ... valve . Learn about the different types of stenosis: Aortic stenosis Tricuspid stenosis Pulmonary stenosis Mitral stenosis Outlook for ... Disease "Innocent" Heart Murmur Problem: Valve Stenosis - Problem: Aortic Valve Stenosis - Problem: Mitral Valve Stenosis - Problem: Tricuspid Valve Stenosis - ...

  10. Heteroscedastic Tests Statistics for One-Way Analysis of Variance: The Trimmed Means and Hall's Transformation Conjunction

    ERIC Educational Resources Information Center

    Luh, Wei-Ming; Guo, Jiin-Huarng

    2005-01-01

    To deal with nonnormal and heterogeneous data for the one-way fixed effect analysis of variance model, the authors adopted a trimmed means method in conjunction with Hall's invertible transformation into a heteroscedastic test statistic (Alexander-Govern test or Welch test). The results of simulation experiments showed that the proposed technique…

  11. Constant Time Delay: One Way to Provide Positive Behavioral Support for Students with Emotional and Behavioral Disorders

    ERIC Educational Resources Information Center

    Stevens, Kay B.; Lingo, Amy S.

    2005-01-01

    Teachers of students with emotional and behavioral disorders (EBD) understand conceptually, emotionally, and legally the importance of using research-based procedures as well as positive behavioral supports. One way to provide positive behavioral support for students with EBD is constant time delay (CTD). CTD is an instructional delivery procedure…

  12. Adjusting for Unequal Variances when Comparing Means in One-Way and Two-Way Fixed Effects ANOVA Models.

    ERIC Educational Resources Information Center

    Wilcox, Rand R.

    1989-01-01

    Two methods of handling unequal variances in the two-way fixed effects analysis of variance (ANOVA) model are described. One is based on an improved Wilcox (1988) method for the one-way model, and the other is an extension of G. S. James' (1951) second order method. (TJH)

  13. Nonparametric One-Way Multivariate Analysis of Variance: A Computational Approach Based on the Pillai-Bartlett Trace.

    ERIC Educational Resources Information Center

    Zwick, Rebecca

    1985-01-01

    Describes how the test statistic for nonparametric one-way multivariate analysis of variance can be obtained by submitting the data to a packaged computer program. Monte Carlo evidence indicates that the nonparametric approach is advantageous under certain violations of the assumptions of multinormality and homogeneity of covariance matrices.…

  14. Depressurization valve

    DOEpatents

    Skoda, George I.

    1989-01-01

    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

  15. One Way or Another

    NASA Technical Reports Server (NTRS)

    Zazzali, Christian

    2003-01-01

    Even experienced project managers can t anticipate every potential problem. Part of planning ahead should include allowing oneself the flexibility to rethink the plan and improvise if necessary. Unique solutions to problems sometimes create a set of new problems unique in nature as well. In dealing with sudden changes in planning, try to consider what other elements of the project will be affected, but don t second guess yourself into a state of inaction because you can t anticipate every contingency.

  16. Nuclear radiation actuated valve

    DOEpatents

    Christiansen, David W.; Schively, Dixon P.

    1985-01-01

    A nuclear radiation actuated valve for a nuclear reactor. The valve has a valve first part (such as a valve rod with piston) and a valve second part (such as a valve tube surrounding the valve rod, with the valve tube having side slots surrounding the piston). Both valve parts have known nuclear radiation swelling characteristics. The valve's first part is positioned to receive nuclear radiation from the nuclear reactor's fuel region. The valve's second part is positioned so that its nuclear radiation induced swelling is different from that of the valve's first part. The valve's second part also is positioned so that the valve's first and second parts create a valve orifice which changes in size due to the different nuclear radiation caused swelling of the valve's first part compared to the valve's second part. The valve may be used in a nuclear reactor's core coolant system.

  17. High-performance one-way transmission using pyramid-shaped silicon grating-coupled hyperbolic metamaterial

    NASA Astrophysics Data System (ADS)

    Hu, Jigang; Qing, Yeming; Wen, Zhengqian; Wu, Xiaohang; Ren, Rongze; Gao, Weiqing; Li, Dongmei; Gao, Feng

    2016-11-01

    An asymmetric transmission device has been presented to realize high-performance one-way transmission at visible frequencies. This device consists of a pair of non-symmetric pyramid-shaped silicon gratings separated by a metal/dielectric multilayer structure (MDMS). Simulation results demonstrates that, compared with conventional Cr grating, MDMS with pyramid-shaped silicon gratings will greatly enhance the coupling and decoupling between the propagating waves in free space and the high frequency modes in MDMS, rendering an improved oneway transmission performance. The improved one-way transmission performance offered by our design may hold great potential in designing the optical isolator and polarizer for ultra-compact photonic integrated circuit.

  18. Exhaled flow monitoring can detect bronchial flap-valve obstruction in a mechanical lung model.

    PubMed

    Breen, P H; Serina, E R; Barker, S J

    1995-08-01

    Flap-valve obstruction to expiratory flow (V) in a major bronchus can result from inspissated secretions, blood, or foreign body. During inhalation, increasing airway caliber preserves inspired V past the obstruction; during exhalation, decreasing airway diameter causes airflow obstruction and even frank gas trapping. We reasoned that the resultant sequential, biphasic exhalation of the lungs would be best detected by measuring exhaled V versus time. Accordingly, we designed an airway obstruction element in a mechanical lung model to examine flap-valve bronchial obstruction. A mechanical lung simulator was ventilated with a pressure-limited flow generator, where f = 10/min, tidal volume = 850 mL, and respiratory compliance = 40 mL/cm H2O. Airway V (pneumotachometer) and pressure (P) were digitally sampled for 1 min. Then, the circumference of the diaphragm in a respiratory one-way valve was trimmed to generate unidirectional resistance to expiratory V. Measurement sequences were repeated after this flap-valve was interposed in the right "main-stem bronchus." Integration of airway V versus time generated changes in lung volume. During flap-valve obstruction of the right bronchus, the V-time plot revealed preservation of peak expired flow from the normal lung, followed by retarded and decreased flow from the obstructed right lung. Gas trapping of the obstructed lung occurred during conditions of decreased expiratory time and increased expiratory resistance. Airway P could not differentiate between bronchial and tracheal flap-valve obstruction because P decreased abruptly in both conditions. The flow-volume loop displayed less distinctive changes than the flow-time plot, in part because the flow-volume loop was data (flow) plotted against its time integral (volume), with loss of temporal data. In this mechanical lung model, we conclude that bronchial flap-valve obstruction was best detected by the flow-time plot, which could measure the sequential emptying of the

  19. Prosthetic valve endocarditis: an overview.

    PubMed

    Gnann, J W; Dismukes, W E

    1983-12-01

    Infection of an intracardiac prosthesis, the incidence of which is about 2.5% among patients having undergone valve replacement, is a serious complication with considerable morbidity and mortality. Early prosthetic valve endocarditis (PVE), with an onset within 60 days of valve replacement, accounts for approximately one-third of all cases, while the remaining two-thirds, occur more than two months postoperatively (late prosthetic valve endocarditis). Prosthetic valve endocarditis is most commonly caused by Staphylococcus epidermidis, less frequently by viridans streptococci, Staphylococcus aureus, and gram-negative bacilli. The most likely pathogenetic mechanisms in prosthetic valve endocarditis are intraoperative contamination and postoperative infections at extracardiac sites. Prominent clinical features include fever, new or changing heart murmurs, leukocytosis, anemia and hematuria. The etiologic microorganism can be isolated in more than 90% of all cases. Patients with proven prosthetic valve endocarditis should be examined daily to detect signs of congestive heart failure and changes in murmurs; electrocardiographic monitoring is essential for documentation of arrhythmias. With limitations, echocardiography, especially two-dimensional, may help to demonstrate vegetations or valvular dehiscence. Cinefluoroscopy may reveal loosening or dehiscence of the sewing ring or impaired motion of a radio-opaque poppet due to thrombus or vegetation. Cardiac catheterization, not always necessary even when surgical intervention is anticipated, may provide valuable information on the degree of dysfunction, multiple valve involvement, left ventricular function and extent of concomitant coronary artery disease. In patients with mechanical valves, prosthetic valve endocarditis may be associated with a high incidence of valve ring and myocardial abscesses; the reported frequency of valve ring abscesses is lower with porcine heterografts. Infections on mechanical valves

  20. Josephson magnetic rotary valve

    SciTech Connect

    Soloviev, I. I.; Klenov, N. V.; Bakurskiy, S. V.; Bol'ginov, V. V.; Ryazanov, V. V.; Kupriyanov, M. Yu.; Golubov, A. A.

    2014-12-15

    We propose a control element for a Josephson spin valve. It is a complex Josephson device containing ferromagnetic (F) layer in the weak-link area consisting of two regions, representing 0 and π Josephson junctions, respectively. The valve's state is defined by mutual orientations of the F-layer magnetization vector and boundary line between 0 and π sections of the device. We consider possible implementation of the control element by introduction of a thin normal metal layer in a part of the device area. By means of theoretical simulations, we study properties of the valve's structure as well as its operation, revealing such advantages as simplicity of control, high characteristic frequency, and good legibility of the basic states.

  1. Aortic Valve Regurgitation

    MedlinePlus

    ... valve. Also, a narrowing of the aortic valve (aortic stenosis) can be associated with leaking. High blood pressure (hypertension). High blood pressure may stretch the root of the aorta where the aortic valve sits. The valve flaps ( ...

  2. Mitral Valve Disease

    MedlinePlus

    ... Heart Disease Diseases of the arteries, valves, and aorta, as well as cardiac rhythm disturbances Aortic Valve ... are two main types of mitral valve disease: Stenosis – the valve does not open enough to allow ...

  3. Experimental realization of one-way quantum computing with two-photon four-qubit cluster states.

    PubMed

    Chen, Kai; Li, Che-Ming; Zhang, Qiang; Chen, Yu-Ao; Goebel, Alexander; Chen, Shuai; Mair, Alois; Pan, Jian-Wei

    2007-09-21

    We report an experimental realization of one-way quantum computing on a two-photon four-qubit cluster state. This is accomplished by developing a two-photon cluster state source entangled both in polarization and spatial modes. With this special source, we implemented a highly efficient Grover's search algorithm and high-fidelity two-qubit quantum gates. Our experiment demonstrates that such cluster states could serve as an ideal source and a building block for rapid and precise optical quantum computation.

  4. A calcified polymeric valve for valve-in-valve applications.

    PubMed

    Falahatpisheh, Ahmad; Morisawa, Daisuke; Toosky, Taraz T; Kheradvar, Arash

    2017-01-04

    The prevalence of aortic valve stenosis (AS) is increasing in the aging society. More recently, novel treatments and devices for AS, especially transcatheter aortic valve replacement (TAVR) have significantly changed the therapeutic approach to this disease. Research and development related to TAVR require testing these devices in the calcified heart valves that closely mimic a native calcific valve. However, no animal model of AS has yet been available. Alternatively, animals with normal aortic valve that are currently used for TAVR experiments do not closely replicate the aortic valve pathology required for proper testing of these devices. To solve this limitation, for the first time, we developed a novel polymeric valve whose leaflets possess calcium hydroxyapatite inclusions immersed in them. This study reports the characteristics and feasibility of these valves. Two types of the polymeric valve, i.e., moderate and severe calcified AS models were developed and tested by deploying a transcatheter valve in those and measuring the related hemodynamics. The valves were tested in a heart flow simulator, and were studied using echocardiography. Our results showed high echogenicity of the polymeric valve, that was correlated to the severity of the calcification. Aortic valve area of the polymeric valves was measured, and the severity of stenosis was defined according to the clinical guidelines. Accordingly, we showed that these novel polymeric valves closely mimic AS, and can be a desired cost-saving solution for testing the performance of the transcatheter aortic valve systems in vitro.

  5. Wear resistant valve

    NASA Technical Reports Server (NTRS)

    Perkins, Gerald S. (Inventor)

    1980-01-01

    A valve which is resistant to wear caused by particles trapped between the valve seat and the valve member or poppet when the valve closes, including an outlet for directing washing fluid at the valve seat and/or sealing face of the poppet and means for supplying pressured fluid to the outlet at the time when the valve is closing.

  6. Intimal sarcoma of the pulmonary valve.

    PubMed

    Scheidl, Stefan; Taghavi, Shahrokh; Reiter, Ursula; Tröster, Natascha; Kovacs, Gabor; Rienmüller, Rainer; Lang, Susanna; Klepetko, Walter; Olschewski, Horst

    2010-04-01

    Pulmonary artery intimal sarcoma is a rare tumor of the cardiovascular system. Intimal sarcoma of the pulmonary valve itself has not been described. Embolization into pulmonary arteries originating from the pulmonary valve intimal sarcoma can mimic chronic thromboembolic pulmonary hypertension and mislead the diagnosis. We present and discuss a patient initially diagnosed as chronic thromboembolic pulmonary hypertension, treated by pulmonary endarterectomy. After 24 months, a tumor of the pulmonary valve was detected by echocardiography. The patient underwent removal and replacement of the pulmonary valve. Histology revealed pulmonary valve intimal sarcoma.

  7. Resource cost results for one-way entanglement distillation and state merging of compound and arbitrarily varying quantum sources

    SciTech Connect

    Boche, H. Janßen, G.

    2014-08-01

    We consider one-way quantum state merging and entanglement distillation under compound and arbitrarily varying source models. Regarding quantum compound sources, where the source is memoryless, but the source state an unknown member of a certain set of density matrices, we continue investigations begun in the work of Bjelaković et al. [“Universal quantum state merging,” J. Math. Phys. 54, 032204 (2013)] and determine the classical as well as entanglement cost of state merging. We further investigate quantum state merging and entanglement distillation protocols for arbitrarily varying quantum sources (AVQS). In the AVQS model, the source state is assumed to vary in an arbitrary manner for each source output due to environmental fluctuations or adversarial manipulation. We determine the one-way entanglement distillation capacity for AVQS, where we invoke the famous robustification and elimination techniques introduced by Ahlswede. Regarding quantum state merging for AVQS we show by example that the robustification and elimination based approach generally leads to suboptimal entanglement as well as classical communication rates.

  8. 49 CFR 236.383 - Valve locks, valves, and valve magnets.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Valve locks, valves, and valve magnets. 236.383... Inspection and Tests § 236.383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off type shall be tested at least once every three months, and valves and valve magnets shall...

  9. 49 CFR 236.383 - Valve locks, valves, and valve magnets.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Valve locks, valves, and valve magnets. 236.383... Inspection and Tests § 236.383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off type shall be tested at least once every three months, and valves and valve magnets shall...

  10. 49 CFR 236.383 - Valve locks, valves, and valve magnets.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Valve locks, valves, and valve magnets. 236.383... Inspection and Tests § 236.383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off type shall be tested at least once every three months, and valves and valve magnets shall...

  11. 49 CFR 236.383 - Valve locks, valves, and valve magnets.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Valve locks, valves, and valve magnets. 236.383... Inspection and Tests § 236.383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off type shall be tested at least once every three months, and valves and valve magnets shall...

  12. 49 CFR 236.383 - Valve locks, valves, and valve magnets.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Valve locks, valves, and valve magnets. 236.383... Inspection and Tests § 236.383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off type shall be tested at least once every three months, and valves and valve magnets shall...

  13. Piezoelectric valve

    SciTech Connect

    Petrenko, Serhiy Fedorovich

    2013-01-15

    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.

  14. Wave Propagation, Scattering and Imaging Using Dual-domain One-way and One-return Propagators

    NASA Astrophysics Data System (ADS)

    Wu, R.-S.

    - Dual-domain one-way propagators implement wave propagation in heterogeneous media in mixed domains (space-wavenumber domains). One-way propagators neglect wave reverberations between heterogeneities but correctly handle the forward multiple-scattering including focusing/defocusing, diffraction, refraction and interference of waves. The algorithm shuttles between space-domain and wavenumber-domain using FFT, and the operations in the two domains are self-adaptive to the complexity of the media. The method makes the best use of the operations in each domain, resulting in efficient and accurate propagators. Due to recent progress, new versions of dual-domain methods overcame some limitations of the classical dual-domain methods (phase-screen or split-step Fourier methods) and can propagate large-angle waves quite accurately in media with strong velocity contrasts. These methods can deliver superior image quality (high resolution/high fidelity) for complex subsurface structures. One-way and one-return (De Wolf approximation) propagators can be also applied to wave-field modeling and simulations for some geophysical problems. In the article, a historical review and theoretical analysis of the Born, Rytov, and De Wolf approximations are given. A review on classical phase-screen or split-step Fourier methods is also given, followed by a summary and analysis of the new dual-domain propagators. The applications of the new propagators to seismic imaging and modeling are reviewed with several examples. For seismic imaging, the advantages and limitations of the traditional Kirchhoff migration and time-space domain finite-difference migration, when applied to 3-D complicated structures, are first analyzed. Then the special features, and applications of the new dual-domain methods are presented. Three versions of GSP (generalized screen propagators), the hybrid pseudo-screen, the wide-angle Padé-screen, and the higher-order generalized screen propagators are discussed. Recent

  15. Excess flow shutoff valve

    DOEpatents

    Kiffer, Micah S.; Tentarelli, Stephen Clyde

    2016-02-09

    Excess flow shutoff valve comprising a valve body, a valve plug, a partition, and an activation component where the valve plug, the partition, and activation component are disposed within the valve body. A suitable flow restriction is provided to create a pressure difference between the upstream end of the valve plug and the downstream end of the valve plug when fluid flows through the valve body. The pressure difference exceeds a target pressure difference needed to activate the activation component when fluid flow through the valve body is higher than a desired rate, and thereby closes the valve.

  16. Confidence intervals and sample size calculations for the weighted eta-squared effect sizes in one-way heteroscedastic ANOVA.

    PubMed

    Shieh, Gwowen

    2013-03-01

    Effect size reporting and interpreting practices have been extensively recommended in academic journals when primary outcomes of all empirical studies have been analyzed. This article presents an alternative approach to constructing confidence intervals of the weighted eta-squared effect size within the context of one-way heteroscedastic ANOVA models. It is shown that the proposed interval procedure has advantages over an existing method in its theoretical justification, computational simplicity, and numerical performance. For design planning, the corresponding sample size procedures for precise interval estimation of the weighted eta-squared association measure are also delineated. Specifically, the developed formulas compute the necessary sample sizes with respect to the considerations of expected confidence interval width and tolerance probability of interval width within a designated value. Supplementary computer programs are provided to aid the implementation of the suggested techniques in practical applications of ANOVA designs when the assumption of homogeneous variances is not tenable.

  17. Comparing One-way and Two-way Coupled Hydrometeorological Forecasting Systems for Flood Forecasting in the Mediterranean Region

    NASA Astrophysics Data System (ADS)

    Givati, Amir; Gochis, David; Rummler, Thomas; Kunstmann, Harald; Yu, Wei

    2016-04-01

    A pair of hydro-meteorological modeling systems were calibrated and evaluated for the Ayalon basin in central Israel to assess the advantages and limitations of one-way versus two-way coupled modeling systems for flood prediction. The models used included the Hydrological Engineering Center-Hydrological Modeling System (HEC-HMS) model and the Weather Research and Forecasting (WRF) Hydro modeling system. The models were forced by observed, interpolated precipitation from rain-gauges within the basin, and with modeled precipitation from the WRF atmospheric model. Detailed calibration and evaluation was carried out for two major winter storms in January and December 2013. Then both modeling systems were executed and evaluated in an operational mode for the full 2014/2015 rainy season. Outputs from these simulations were compared to observed measurements from hydrometric stations at the Ayalon basin outlet. Various statistical metrics were employed to quantify and analyze the results: correlation, Root Mean Square Error (RMSE) and the Nash-Sutcliffe (NS) efficiency coefficient. Foremost, the results presented in this study highlight the sensitivity of hydrological responses to different sources of precipitation data, and less so, to hydrologic model formulation. With observed precipitation data both calibrated models closely simulated the observed hydrographs. The two-way coupled WRF/WRF-Hydro modeling system produced improved both the precipitation and hydrological simulations as compared to the one-way WRF simulations. Findings from this study suggest that the use of two-way atmospheric-hydrological coupling has the potential to improve precipitation and, therefore, hydrological forecasts for early flood warning applications. However more research needed in order to better understand the land-atmosphere coupling mechanisms driving hydrometeorological processes on a wider variety precipitation and terrestrial hydrologic systems.

  18. Wide-angle elastic wave one-way propagation in heterogeneous media and an elastic wave complex-screen method

    NASA Astrophysics Data System (ADS)

    Wu, Ru-Shan

    1994-01-01

    In this paper a system of equations for wide-angle one-way elastic wave propagation in arbitrarily heterogeneous media is formulated in both the space and wavenumber domains using elastic Rayleigh integrals and local elastic Born scattering theory. The wavenumber domain formulation leads to compact solutions to one-way propagation and scattering problems. It is shown that wide-angle scattering in heterogeneous elastic media cannot be formulated as passage through regular phase-screens, since the interaction between the incident wavefield and the heterogeneities is not local in both the space domain and the wavenumber domain. Our more generally valid formulation is called the 'thin-slap; formulation. After applying the small-angle approximation, the thin slab effect degenerates to that of an elastic complex-screen (or generalized phase-screen). For the complex-screen method the cross-coupling term is neglected because it is higher order small quantity for small-angle scattering. Relative to prior derivations of vector phase-screen method, our method can correctly treat the conversion between P and S waves and the cross-coupling between differently polarized S waves. A comparison with solutions from three-dimensional finite difference and exact solutions using eigenfunctions expansion is made for two special cases. One is for a solid sphere with only P velocity pertubation; the other is with only S velocity perturbation. The Elastic complex-screen method generally agrees well with the three-dimensional finite difference method and the exact solutions. In the limiting case of scalar waves, the derivation in this paper leads to a move generally valid new method, namely, a scaler thin-slab method. When making the small-angle approximation to the interaction term while keeping the propagation term unchanged, the thin-slab method approaches the currently available scalar wide-angle phase screen method.

  19. ELECTROSTRICTION VALVE

    DOEpatents

    Kippenhan, D.O.

    1962-09-25

    An accurately controlled, pulse gas valve is designed capable of delivering output pulses which vary in length from one-tenth millisecond to one second or more, repeated at intervals of a few milliseconds or- more. The pulsed gas valve comprises a column formed of barium titanate discs mounted in stacked relation and electrically connected in parallel, with means for applying voltage across the discs to cause them to expand and effect a mechanical elongation axially of the column. The column is mounted within an enclosure having an inlet port and an outlet port with an internal seat in communication with the outlet port, such that a plug secured to the end of the column will engage the seat of the outlet port to close the outlet port in response to the application of voltage is regulated by a conventional electronic timing circuit connected to the column. (AEC)

  20. Dump valve

    SciTech Connect

    Webber, J.C.

    1981-06-23

    A swab assembly is provided having a dump valve responsive to fluid pressure and drag which will dump the fluid load should either fluid load or drag or the effect of both fluid load and drag become abnormal. Also if the fluid pressure and/or drag become abnormal, the fluid load on the cup will be released and wash away foreign material causing abnormal drag. When the cup is dumped the pulling capabilities of the wireline truck can concentrate on overcoming the drag. The dump valve opens to wide open position and remains open to dump the fluid to assist in washing away solid materials above the cup. A swab assembly also is provided which with normal drag and an overload, may be pulled relatively slowly, but if pulled too rapidly will result in the load on the swab being dumped to protect the swab assembly and the pulling apparatus from damage. 15 claims.

  1. A one-way coupled, Euler-Lagrangian simulation of bubble coalescence in a turbulent pipe flow

    NASA Astrophysics Data System (ADS)

    Mattson, Michael; Mahesh, Krishnan

    2011-11-01

    A bubble coalescence model is developed using an Euler-Lagrangian approach for unstructured grids. The Eulerian carrier fluid is solved using large-eddy simulation (LES) and the Lagrangian particle motion is solved using one-way coupled equations relating the turbulent motion of the carrier fluid to the forces on each discrete bubble. The collision process is deterministic; bubble-bubble collisions are assumed to be binary and are modeled using a hard-sphere approach. A stochastic approach is used to model coalescence, with the probability of coalescence being a function of the bubble-bubble interaction timescale and the time to drain fluid between the colliding bubbles. Coalescence in a bubbly, turbulent pipe flow without buoyancy is simulated with conditions similar to a microgravity experiment by Colin, Fabre and Dukler [Int. J. Multiphase Flow (1991) 17:533-544] and excellent agreement of bubble size distribution is obtained between simulation and experiment. With increasing downstream distance, the number density of bubbles decreases due to coalescence and the average probability of coalescence decreases slightly due to an increase in overall bubble size. Supported by the U.S. Office of Naval Research under ONR Grant N00014-07-1-0420.

  2. One-way domain decomposition method with exact radiation condition and fast GMRES solver for the solution of Maxwell's equations

    NASA Astrophysics Data System (ADS)

    Stupfel, Bruno; Lecouvez, Matthieu

    2016-10-01

    For the solution of the time-harmonic electromagnetic scattering problem by inhomogeneous 3-D objects, a one-way domain decomposition method (DDM) is considered: the computational domain is partitioned into concentric subdomains on the interfaces of which Robin-type transmission conditions (TCs) are prescribed; an integral representation of the electromagnetic fields on the outer boundary constitutes an exact radiation condition. The global system obtained after discretization of the finite element (FE) formulations is solved via a Krylov subspace iterative method (GMRES). It is preconditioned in such a way that, essentially, only the solution of the FE subsystems in each subdomain is required. This is made possible by a computationally cheap H (curl)- H (div) transformation performed on the interfaces that separate the two outermost subdomains. The eigenvalues of the preconditioned matrix of the system are bounded by two, and optimized values of the coefficients involved in the local TCs on the interfaces are determined so as to maximize the minimum eigenvalue. Numerical experiments are presented that illustrate the numerical accuracy of this technique, its fast convergence, and legitimate the choices made for the optimized coefficients.

  3. Investigation of crystal structures of one-way shape memory Nitinol wire actuators for active steerable needle

    NASA Astrophysics Data System (ADS)

    Honarvar, Mohammad; Konh, Bardia; Hutapea, Parsaoran

    2015-04-01

    Due to its outstanding properties of Nitinol, known as shape memory and superelasticity, Nitinol wires have been used as actuators in many medical devices. For the medical applications, it is critical to have a consistent strain response of Nitinol wires. This work focuses on studying the effect of parameters such as biased stress, maximum temperature, and wire diameters that influence the strain response of Nitinol wires. Specifically, Nitinol phase transformations were studied from microstructural point of view. The crystal structures of one-way shape memory Nitinol wires of various diameters under different thermomechanical loading conditions were studied using X-Ray Diffraction (XRD) method. The location and intensity of characteristic peaks were determined prior and after the thermomechanical loading cycles. It was observed that Nitinol wires of diameters less than 0.19 mm exhibit unrecovered strain while heated to the range of 70ºC to 80ºC in a thermal cycle, whereas no unrecovered strains were found in larger wires. The observation was supported by the XRD patterns where the formation of R-phase crystal structure was showed in wire diameters less than 0.19 mm at room temperature.

  4. Rectification and one-way street for the energy current in boundary-driven asymmetric quantum spin chains

    NASA Astrophysics Data System (ADS)

    Pereira, Emmanuel

    2017-03-01

    Motivated by the demand for efficient quantum devices to engineer energy transport, we analyze some inhomogeneous quantum spin systems, including X X Z chains, with magnetization baths at the ends. With a goal of finding general properties, we study the effects of suitable transformations on the boundary-driven Lindblad master equation associated with the dynamics of the systems. For asymmetric models with target polarization at the edges or twisted X Y boundary gradients, we show the properties of the steady state, which establish the features of the energy current irrespective of the system size and the regime of transport. We show the ubiquitous occurrence of energy rectification and, more interestingly, of an unusual phenomenon: in the absence of an external magnetic field, there is a one-way street for the energy current, i.e., the direction of the energy current does not change as we invert the magnetization baths at the boundaries. Given the extensiveness of the procedures, which essentially involve the properties of the Lindblad master equation, our results certainly follow for other interactions and other boundary conditions. Moreover, our results indicate graded spin chains as genuine quantum rectifiers.

  5. Assessing Fan Flutter Stability in the Presence of Inlet Distortion Using One-way and Two-way Coupled Methods

    NASA Technical Reports Server (NTRS)

    Herrick, Gregory P.

    2014-01-01

    Concerns regarding noise, propulsive efficiency, and fuel burn are inspiring aircraft designs wherein the propulsive turbomachines are partially (or fully) embedded within the airframe; such designs present serious concerns with regard to aerodynamic and aeromechanic performance of the compression system in response to inlet distortion. Previously, a preliminary design of a forward-swept high-speed fan exhibited flutter concerns in cleaninlet flows, and the present author then studied this fan further in the presence of off-design distorted in-flows. Continuing this research, a three-dimensional, unsteady, Navier-Stokes computational fluid dynamics code is again applied to analyze and corroborate fan performance with clean inlet flow and now with a simplified, sinusoidal distortion of total pressure at the aerodynamic interface plane. This code, already validated in its application to assess aerodynamic damping of vibrating blades at various flow conditions using a one-way coupled energy-exchange approach, is modified to include a two-way coupled time-marching aeroelastic simulation capability. The two coupling methods are compared in their evaluation of flutter stability in the presence of distorted in-flows.

  6. Assessing Fan Flutter Stability in Presence of Inlet Distortion Using One-Way and Two-Way Coupled Methods

    NASA Technical Reports Server (NTRS)

    Herrick, Gregory P.

    2014-01-01

    Concerns regarding noise, propulsive efficiency, and fuel burn are inspiring aircraft designs wherein the propulsive turbomachines are partially (or fully) embedded within the airframe; such designs present serious concerns with regard to aerodynamic and aeromechanic performance of the compression system in response to inlet distortion. Previously, a preliminary design of a forward-swept high-speed fan exhibited flutter concerns in clean-inlet flows, and the present author then studied this fan further in the presence of off-design distorted in-flows. Continuing this research, a three-dimensional, unsteady, Navier-Stokes computational fluid dynamics code is again applied to analyze and corroborate fan performance with clean inlet flow and now with a simplified, sinusoidal distortion of total pressure at the aerodynamic interface plane. This code, already validated in its application to assess aerodynamic damping of vibrating blades at various flow conditions using a one-way coupled energy-exchange approach, is modified to include a two-way coupled timemarching aeroelastic simulation capability. The two coupling methods are compared in their evaluation of flutter stability in the presence of distorted in-flows.

  7. Challenging the One-Way Paradigm for More Effective Science Communication: A Critical Review of Two Public Campaigns Addressing Contentious Environmental Issues

    ERIC Educational Resources Information Center

    McEntee, Marie; Mortimer, Claire

    2013-01-01

    This article examines two large-scale public communication campaigns to explore the appropriateness and effectiveness of using one-way communication in contentious environmental issues. The findings show while one-way communication can be successfully employed in contentious issues, it is not appropriate for all contexts and may contribute to…

  8. Mitral Valve Prolapse

    MedlinePlus

    ... Personal Stories Support Network: You're Not Alone Heart Valve Disease Symptoms Dr. Robert Bonow describes the symptoms that may alert you to heart valve disease. Valve Disease Resources Patient Guide: Understanding Your Heart ...

  9. Automatic shutoff valve

    NASA Technical Reports Server (NTRS)

    Hawkins, S. F.; Overbey, C. W.

    1980-01-01

    Cellulose-sponge disk absorbs incoming water and expands with enough force to shut valve. When water recedes, valve opens by squeezing sponge dry to its original size. This direct mechanical action is considered more reliable than solenoid valve.

  10. Mitral Valve Prolapse

    MedlinePlus

    Mitral valve prolapse (MVP) occurs when one of your heart's valves doesn't work properly. The flaps of ... Migraine headaches Chest discomfort Most people who have mitral valve prolapse (MVP) don't need treatment because they ...

  11. Two-way against one-way nesting for climate downscaling in Europe and the Mediterranean region using LMDZ4

    NASA Astrophysics Data System (ADS)

    Li, Shan; Li, Laurent; Le Treut, Hervé

    2016-04-01

    In the 21st century, the estimated surface temperature warming projected by General Circulation Models (GCMs) is between 0.3 and 4.8 °C, depending on the scenario considered. GCMs exhibit a good representation of climate on a global scale, but they are not able to reproduce regional climate processes with the same level of accuracy. Society and policymakers need model projections to define climate change adaptation and mitigation policies on a global, regional and local scale. Climate downscaling is mostly conducted with a regional model nested into the outputs of a global model. This one-way nesting approach is generally used in the climate community without feedbacks from Regional Climate Models (RCMs) to GCMs. This lack of interaction between the two models may affect regional modes of variability, in particular those with a boundary conflict. The objective of this study is to evaluate a two-way nesting configuration that makes an interactive coupling between the RCM and the GCM, an approach against the traditional configuration of one-way nesting system. An additional aim of this work is to examine if the two-way nesting system can improve the RCM performance. The atmospheric component of the IPSL integrated climate model (LMDZ) is configured at both regional (LMDZ-regional) and global (LMDZ-global) scales. The two models have the same configuration for the dynamical framework and the physical forcings. The climatology values of sea surface temperature (SST) are prescribed for the two models. The stretched-grid of LMDZ-global is applied to a region defined by Europe, the Mediterranean, North Africa and Western North Atlantic. To ensure a good statistical significance of results, all simulations last at least 80 years. The nesting process of models is performed by a relaxation procedure of a time scale of 90 minutes. In the case of two-way nesting, the exchange between the two models is every two hours. The relaxation procedure induces a boundary conflict

  12. Magnetically operated check valve

    NASA Technical Reports Server (NTRS)

    Morris, Brian G. (Inventor); Bozeman, Richard J., Jr. (Inventor)

    1994-01-01

    A magnetically operated check valve is disclosed. The valve is comprised of 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.

  13. Magnetically operated check valve

    NASA Astrophysics Data System (ADS)

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

    1994-06-01

    A magnetically operated check valve is disclosed. The valve is comprised of 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.

  14. Fast-Acting Valve

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    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.

  15. Is there more than one way to skin a newt? Convergent toxin resistance in snakes is not due to a common genetic mechanism

    PubMed Central

    Feldman, C R; Durso, A M; Hanifin, C T; Pfrender, M E; Ducey, P K; Stokes, A N; Barnett, K E; Brodie III, E D; Brodie Jr, E D

    2016-01-01

    Convergent evolution of tetrodotoxin (TTX) resistance, at both the phenotypic and genetic levels, characterizes coevolutionary arms races between amphibians and their snake predators around the world, and reveals remarkable predictability in the process of adaptation. Here we examine the repeatability of the evolution of TTX resistance in an undescribed predator–prey relationship between TTX-bearing Eastern Newts (Notophthalmus viridescens) and Eastern Hog-nosed Snakes (Heterodon platirhinos). We found that that local newts contain levels of TTX dangerous enough to dissuade most predators, and that Eastern Hog-nosed Snakes within newt range are highly resistant to TTX. In fact, these populations of Eastern Hog-nosed Snakes are so resistant to TTX that the potential for current reciprocal selection might be limited. Unlike all other cases of TTX resistance in vertebrates, H. platirhinos lacks the adaptive amino acid substitutions in the skeletal muscle sodium channel that reduce TTX binding, suggesting that physiological resistance in Eastern Hog-nosed Snakes is conferred by an alternate genetic mechanism. Thus, phenotypic convergence in this case is not due to parallel molecular evolution, indicating that there may be more than one way for this adaptation to arise, even among closely related species. PMID:26374236

  16. Rotary pneumatic valve

    DOEpatents

    Hardee, Harry C.

    1991-01-01

    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.

  17. Liquid rocket valve components

    NASA Technical Reports Server (NTRS)

    1973-01-01

    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.

  18. Remote actuated valve implant

    DOEpatents

    McKnight, Timothy E; Johnson, Anthony; Moise, Jr., Kenneth J; Ericson, Milton Nance; Baba, Justin S; Wilgen, John B; Evans, III, Boyd McCutchen

    2014-02-25

    Valve implant systems positionable within a flow passage, the systems having an inlet, an outlet, and a remotely activatable valve between the inlet and outlet, with the valves being operable to provide intermittent occlusion of the flow path. A remote field is applied to provide thermal or magnetic activation of the valves.

  19. Microfluidic sieve valves

    DOEpatents

    Quake, Stephen R; Marcus, Joshua S; Hansen, Carl L

    2015-01-13

    Sieve valves for use in microfluidic device are provided. The valves are useful for impeding the flow of particles, such as chromatography beads or cells, in a microfluidic channel while allowing liquid solution to pass through the valve. The valves find particular use in making microfluidic chromatography modules.

  20. Early Mission Orbit Determination Error Analysis Results for Low-Earth Orbiting Missions using TDRSS Differenced One-way Doppler Tracking Data

    NASA Technical Reports Server (NTRS)

    Marr, Greg C.

    2003-01-01

    Differencing multiple, simultaneous Tracking and Data Relay Satellite System (TDRSS) one-way Doppler passes can yield metric tracking data usable for orbit determination for (low-cost) spacecraft which do not have TDRSS transponders or local oscillators stable enough to allow the one-way TDRSS Doppler tracking data to be used for early mission orbit determination. Orbit determination error analysis results are provided for low Earth orbiting spacecraft for various early mission tracking scenarios.

  1. Dual stage check valve

    NASA Technical Reports Server (NTRS)

    Whitten, D. E. (Inventor)

    1973-01-01

    A dual stage seat valve head arrangement is described which consists of a primary sealing point located between a fixed orifice seat and a valve poppet, and a secondary sealing point between an orifice poppet and a valve poppet. Upstream of the valve orifice is a flexible, convoluted metal diaphragm attached to the orifice poppet. Downstream of the valve orifice, a finger spring exerts a force against the valve poppet, tending to keep the valve in a closed position. The series arrangement of a double seat and poppet is able to tolerate small particle contamination while minimizing chatter by controlling throttling or metering across the secondary seat, thus preserving the primary sealing surface.

  2. Double valve Implantation

    PubMed Central

    Stassano, Paolo; Mannacio, Vito; Musumeci, Antonino; Golino, Alessandro; Maida, Piero; Ferrigno, Vincenzo; Buonocore, Gaetano; Spampinato, Nicola

    1991-01-01

    From January 1976 through December 1987, 194 patients with a mean age of 43.3 ± 13.7 years (range, 11 to 74 years) underwent double (mitral and aortic) replacement of native valves with 8 types of bioprostheses: Carpentier-Edwards, 127 valves; Hancock, 76 valves; Liotta-Bioimplant, 57 valves; Ionescu-Shiley, 53 valves; Vascor, 27 valves; Carpentier-Edwards Pericardial, 22 valves; Angell-Shiley, 20 valves; and Implamedic, 6 valves. Concomitant cardiac procedures were performed in 25 patients (12.8%). There were 18 operative deaths (9.27%). Our retrospective analysis was restricted to 352 bioprostheses implanted in the 176 patients who survived surgery and were considered at risk for valve tissue failure. The overall cumulative duration of follow-up was 1,174.1 patient-years (range, 1 to 13 years). The durations of follow-up for specific valves were: Carpentier-Edwards, 920.2 valve-years; Hancock, 383.8 valve-years; Liotta-Bioimplant, 310.2 valve-years; Ionescu-Shiley, 357.7 valve-years; Vascor, 131.2 valve-years; Carpentier-Edwards Pericardial, 52.0 valve-years; Angell-Shiley, 167.0 valve-years; and Implamedic, 31.0 valve-years. Thirty patients had thromboembolic accidents, for a linearized incidence of 2.5% per patient-year. At 13 years, the actuarial freedom from thromboembolic accidents was 85.8% ± 10.7%. Nine patients had endocarditis, for a linearized incidence of 0.7% per patient-year. At 13 years, the actuarial freedom from endocarditis was 92.0% ± 1.5%. Twenty-four patients had valve tissue failure, for a cumulative linearized incidence of 1.87% per valve-year. The cumulative actuarial probability of freedom from valve tissue failure was 78.6% ± 3.7% at 10 years and 51.2% ± 10.7% at 13 years. The 24 patients with valve tissue failure all underwent reoperation: 20 of these had double valve replacement, 3 had aortic valve replacement alone, and 1 had mitral valve replacement alone. The mean interval between initial valve implantation and reoperation was

  3. Valve-in-Valve Replacement Using a Sutureless Aortic Valve

    PubMed Central

    Dohmen, Pascal M.; Lehmkuhl, Lukas; Borger, Michael A.; Misfeld, Martin; Mohr, Friedrich W.

    2016-01-01

    Patient: Female, 61 Final Diagnosis: Tissue degeneration Symptoms: Dyspnea Medication: — Clinical Procedure: Redo valve replacement Specialty: Surgery Objective: Rare disease Background: We present a unique case of a 61-year-old female patient with homograft deterioration after redo surgery for prosthetic valve endocarditis with root abscess. Case Report: The first operation was performed for type A dissection with root, arch, and elephant trunk replacement of the thoracic aorta. The present re-redo surgery was performed as valve-in-valve with a sutureless aortic biopros-thesis. The postoperative course was uneventful and the patient was discharged on day 6. Conclusions: The current case report demonstrates that sutureless bioprostheses are an attractive option for surgical valve-in-valve procedures, which can reduce morbidity and mortality. PMID:27694795

  4. Vacuum breaker valve assembly

    DOEpatents

    Thompson, Jeffrey L.; Upton, Hubert Allen

    1999-04-27

    Breaker valve assemblies for a simplified boiling water nuclear reactor are described. The breaker valve assembly, in one form, includes a valve body and a breaker valve. The valve body includes an interior chamber, and an inlet passage extends from the chamber and through an inlet opening to facilitate transporting particles from outside of the valve body to the interior chamber. The breaker valve is positioned in the chamber and is configured to substantially seal the inlet opening. Particularly, the breaker valve includes a disk which is sized to cover the inlet opening. The disk is movably coupled to the valve body and is configured to move substantially concentrically with respect to the valve opening between a first position, where the disk completely covers the inlet opening, and a second position, where the disk does not completely cover the inlet opening.

  5. Bellows sealed plug valve

    DOEpatents

    Dukas, Jr., Stephen J.

    1990-01-01

    A bellows sealed plug valve includes a valve body having an inlet passage and an outlet passage, a valve chamber between the inlet and outlet passages. A valve plug has substantially the same shape as the valve chamber and is rotatably disposed therein. A shaft is movable linearly in response to a signal from a valve actuator. A bellows is sealingly disposed between the valve chamber and the valve actuator and means are located between the bellows and the valve plug for converting linear movement of the shaft connected to the valve actuator to rotational movement of the plug. Various means are disclosed including helical thread mechanism, clevis mechanism and rack and pinion mechanism, all for converting linear motion to rotational motion.

  6. Scissor thrust valve actuator

    DOEpatents

    DeWall, Kevin G.; Watkins, John C; Nitzel, Michael E.

    2006-08-29

    Apparatus for actuating a valve includes a support frame and at least one valve driving linkage arm, one end of which is rotatably connected to a valve stem of the valve and the other end of which is rotatably connected to a screw block. A motor connected to the frame is operatively connected to a motor driven shaft which is in threaded screw driving relationship with the screw block. The motor rotates the motor driven shaft which drives translational movement of the screw block which drives rotatable movement of the valve driving linkage arm which drives translational movement of the valve stem. The valve actuator may further include a sensory control element disposed in operative relationship with the valve stem, the sensory control element being adapted to provide control over the position of the valve stem by at least sensing the travel and/or position of the valve stem.

  7. Heart valve surgery - series (image)

    MedlinePlus

    There are four valves in the heart: aortic valve, mitral valve, tricuspid valve, and pulmonary valve. The valves are designed to control the direction of blood flow through the heart. The opening and closing of the heart valves produce the heart-beat sounds.

  8. Magnetically operated check valve

    NASA Astrophysics Data System (ADS)

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

    1993-03-01

    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.

  9. When a Heart Murmur Signals Valve Disease

    MedlinePlus

    ... Problem: Valve Stenosis - Problem: Aortic Valve Stenosis - Problem: Mitral Valve Stenosis - Problem: Tricuspid Valve Stenosis - Problem: Pulmonary Valve Stenosis Problem: Mitral Valve Prolapse Problem: Heart Valve Regurgitation - Problem: Aortic ...

  10. Arachnoid cyst slit valves: the mechanism for arachnoid cyst enlargement.

    PubMed

    Halani, Sameer H; Safain, Mina G; Heilman, Carl B

    2013-07-01

    Arachnoid cysts are common, accounting for approximately 1% of intracranial mass lesions. Most are congenital, clinically silent, and remain static in size. Occasionally, they increase in size and produce symptoms due to mass effect or obstruction. The mechanism of enlargement of arachnoid cysts is controversial. One-way slit valves are often hypothesized as the mechanism for enlargement. The authors present 4 cases of suprasellar prepontine arachnoid cysts in which a slit valve was identified. The patients presented with hydrocephalus due to enlargement of the cyst. The valve was located in the arachnoid wall of the cyst directly over the basilar artery. The authors believe this slit valve was responsible for the net influx of CSF into the cyst and for its enlargement. They also present 1 case of an arachnoid cyst in the middle cranial fossa that had a small circular opening but lacked a slit valve. This cyst did not enlarge but surgery was required because of rupture and the development of a subdural hygroma. One-way slit valves exist and are a possible mechanism of enlargement of suprasellar prepontine arachnoid cysts. The valve was located directly over the basilar artery in each of these cases. Caudad-to-cephalad CSF flow during the cardiac cycle increased the opening of the valve, whereas cephalad-to-caudad CSF flow during the remainder of the cardiac cycle pushed the slit opening against the basilar artery and decreased the size of the opening. Arachnoid cysts that communicate CSF via circular, nonslit valves are probably more likely to remain stable.

  11. Fast acting check valve

    NASA Technical Reports Server (NTRS)

    Perkins, Gerald S. (Inventor)

    1979-01-01

    A check valve which closes more rapidly to prevent wearing of the valve seat and of the valve member that seals thereagainst, including a solenoid or other actuator that aids the normal spring to quickly close the valve at approximately the time when downpath fluid flow would stop, the actuator then being deenergized. The control circuit that operates the actuator can include a pair of pressure sensors sensing pressure both upstream and downstream from the valve seat. Where the valve is utilized to control flow to or from a piston pump, energization of the actuator can be controlled by sensing when the pump piston reaches its extreme of travel.

  12. Quickly Removable Valve

    NASA Technical Reports Server (NTRS)

    Robbins, John S.

    1988-01-01

    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.

  13. Ball valve extractor

    DOEpatents

    Herndon, Charles; Brown, Roger A.

    2002-01-01

    An apparatus and process for removing a ball valve is provided. The ball valve removal tool provides a handle sliding along the length of a shaft. One end of the shaft is secured within an interior cavity of a ball valve while the opposite end of the shaft defines a stop member. By providing a manual sliding force to the handle, the handle impacts the stop member and transmits the force to the ball valve. The direction of the force is along the shaft of the removal tool and disengages the ball valve from the ball valve housing.

  14. Cosmic background explorer (COBE) navigation with TDRSS one-way return-link Doppler in the post-helium-venting phase

    NASA Technical Reports Server (NTRS)

    Nemesure, M.; Dunham, J.; Maher, M.; Teles, J.; Jackson, J.

    1991-01-01

    A navigation experiment was performed which establishes Ultra-Stable Oscillator (USO) frequency stabilized one way return link Doppler TDRSS tracking data as a feasible option for mission orbit determination support at the Goddard Space Center Flight Dynamics Facility. The study was conducted using both one way and two way Tracking and Data Relay Satellite System (TDRSS) tracking measurements for the Cosmic Background Explorer (COBE) spacecraft. Tracking data for a 4 week period immediately follow the depletion of the helium supply was used. The study showed that, for both definitive orbit solution and short term orbit prediction (up to 4 weeks), orbit determination results based on one way return link Doppler tracking measurements are comparable to orbit determination results based on two way range and two way Doppler tracking measurements.

  15. Cosmic background explorer (COBE) navigation with TDRSS one-way return-link Doppler in the post-helium-venting phase

    NASA Astrophysics Data System (ADS)

    Nemesure, M.; Dunham, J.; Maher, M.; Teles, J.; Jackson, J.

    1991-10-01

    A navigation experiment was performed which establishes Ultra-Stable Oscillator (USO) frequency stabilized one way return link Doppler TDRSS tracking data as a feasible option for mission orbit determination support at the Goddard Space Center Flight Dynamics Facility. The study was conducted using both one way and two way Tracking and Data Relay Satellite System (TDRSS) tracking measurements for the Cosmic Background Explorer (COBE) spacecraft. Tracking data for a 4 week period immediately follow the depletion of the helium supply was used. The study showed that, for both definitive orbit solution and short term orbit prediction (up to 4 weeks), orbit determination results based on one way return link Doppler tracking measurements are comparable to orbit determination results based on two way range and two way Doppler tracking measurements.

  16. Living with Heart Valve Disease

    MedlinePlus

    ... page from the NHLBI on Twitter. Living With Heart Valve Disease Heart valve disease is a lifelong condition. However, ... all of your medicines as prescribed. Pregnancy and Heart Valve Disease Mild or moderate heart valve disease during pregnancy ...

  17. Rare Case of Unileaflet Mitral Valve.

    PubMed

    Shah, Jainil; Jain, Tarun; Shah, Sunay; Mawri, Sagger; Ananthasubramaniam, Karthikeyan

    2016-06-01

    Unileaflet mitral valve is the rarest of the congenital mitral valve anomalies and is usually life threatening in infancy due to severe mitral regurgitation (MR). In most asymptomatic individuals, it is mostly due to hypoplastic posterior mitral leaflet. We present a 22-year-old male with palpitations, who was found to have an echocardiogram revealing an elongated anterior mitral valve leaflet with severely hypoplastic posterior mitral valve leaflet appearing as a unileaflet mitral valve without MR. Our case is one of the 11 reported cases in the literature so far. We hereby review those cases and conclude that these patients are likely to be at risk of developing worsening MR later in their lives.

  18. One-way return-link Doppler navigation with the Tracking and Data Satellite System (TDRSS) - The ultrastable oscillator (USO) experiment on the Cosmic Background Explorer (COBE)

    NASA Astrophysics Data System (ADS)

    Dunham, J. B.; Nemesure, M.; Teles, J.; Brown-Conwell, E. R.; Jackson, J. A.; Reamy, V. L.; Maher, M. J.; Elrod, B. D.

    The principal objectives of the USO experiment on the COBE spacecraft are defined, and results of space qualification studies for the COBE USO experiment are summarized. The principal objectives of the experiment are: (1) to determine flight performance of the USO coupled to the second-generation TDRSS transponder; (2) space qualify TDRSS noncoherent one-way return-link Doppler tracking; and (3) analyze algorithms for one-way navigation with real data. The three objectives of the experiment have been met in the first stage of the experiment analysis.

  19. Valve mechanism having variable valve timing

    SciTech Connect

    Oda, H.; Masuda, S.; Morita, Y.

    1986-04-08

    This patent describes a valve mechanism for an internal combustion engine which consists of a camshaft rotatable about a longitudinal axis and having a cam formed thereon, a swingable member mounted for swinging movement about the longitudinal axis of the camshaft and formed with a tappet receiving hole. A valve tapper is received in the tappet receiving hole for a slidable movement along the tappet receiving hole. The tappet has a cam which engages the surface at one end and a stem engages the surface at the other end. A valve stem is mounted for axial movement and engaged at one end with the stem engaging, surface of the tappet to be actuated thereby. A valve timing control swingably moves the swingable member and the tappet about the camshaft axis in accordance with predetermined engine operating conditions to thereby change valve opening and valve closing timing. The control includes means for holding the swingable member at a first position. The tappet and valve stem are in contact at a first position on the stem engaging surface of the tappet and the direction of the slidable movement of the tappet is aligned with the direction of the axial movement of the valve stem at least under heavy load, high speed engine operation, and for moving the swingable member from the first position to a second position. The tappet and valve stem are in contact at a second position on the stem engaging surface of the tappet at low speed engine operation to effect a change in valve opening and valve closing timing.

  20. Mitral valve disease—morphology and mechanisms

    PubMed Central

    Levine, Robert A.; Hagége, Albert A.; Judge, Daniel P.; Padala, Muralidhar; Dal-Bianco, Jacob P.; Aikawa, Elena; Beaudoin, Jonathan; Bischoff, Joyce; Bouatia-Naji, Nabila; Bruneval, Patrick; Butcher, Jonathan T.; Carpentier, Alain; Chaput, Miguel; Chester, Adrian H.; Clusel, Catherine; Delling, Francesca N.; Dietz, Harry C.; Dina, Christian; Durst, Ronen; Fernandez-Friera, Leticia; Handschumacher, Mark D.; Jensen, Morten O.; Jeunemaitre, Xavier P.; Le Marec, Hervé; Le Tourneau, Thierry; Markwald, Roger R.; Mérot, Jean; Messas, Emmanuel; Milan, David P.; Neri, Tui; Norris, Russell A.; Peal, David; Perrocheau, Maelle; Probst, Vincent; Pucéat, Michael; Rosenthal, Nadia; Solis, Jorge; Schott, Jean-Jacques; Schwammenthal, Ehud; Slaugenhaupt, Susan A.; Song, Jae-Kwan; Yacoub, Magdi H.

    2016-01-01

    Mitral valve disease is a frequent cause of heart failure and death. Emerging evidence indicates that the mitral valve is not a passive structure, but—even in adult life—remains dynamic and accessible for treatment. This concept motivates efforts to reduce the clinical progression of mitral valve disease through early detection and modification of underlying mechanisms. Discoveries of genetic mutations causing mitral valve elongation and prolapse have revealed that growth factor signalling and cell migration pathways are regulated by structural molecules in ways that can be modified to limit progression from developmental defects to valve degeneration with clinical complications. Mitral valve enlargement can determine left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and might be stimulated by potentially modifiable biological valvular–ventricular interactions. Mitral valve plasticity also allows adaptive growth in response to ventricular remodelling. However, adverse cellular and mechanobiological processes create relative leaflet deficiency in the ischaemic setting, leading to mitral regurgitation with increased heart failure and mortality. Our approach, which bridges clinicians and basic scientists, enables the correlation of observed disease with cellular and molecular mechanisms, leading to the discovery of new opportunities for improving the natural history of mitral valve disease. PMID:26483167

  1. Mitral valve disease--morphology and mechanisms.

    PubMed

    Levine, Robert A; Hagége, Albert A; Judge, Daniel P; Padala, Muralidhar; Dal-Bianco, Jacob P; Aikawa, Elena; Beaudoin, Jonathan; Bischoff, Joyce; Bouatia-Naji, Nabila; Bruneval, Patrick; Butcher, Jonathan T; Carpentier, Alain; Chaput, Miguel; Chester, Adrian H; Clusel, Catherine; Delling, Francesca N; Dietz, Harry C; Dina, Christian; Durst, Ronen; Fernandez-Friera, Leticia; Handschumacher, Mark D; Jensen, Morten O; Jeunemaitre, Xavier P; Le Marec, Hervé; Le Tourneau, Thierry; Markwald, Roger R; Mérot, Jean; Messas, Emmanuel; Milan, David P; Neri, Tui; Norris, Russell A; Peal, David; Perrocheau, Maelle; Probst, Vincent; Pucéat, Michael; Rosenthal, Nadia; Solis, Jorge; Schott, Jean-Jacques; Schwammenthal, Ehud; Slaugenhaupt, Susan A; Song, Jae-Kwan; Yacoub, Magdi H

    2015-12-01

    Mitral valve disease is a frequent cause of heart failure and death. Emerging evidence indicates that the mitral valve is not a passive structure, but--even in adult life--remains dynamic and accessible for treatment. This concept motivates efforts to reduce the clinical progression of mitral valve disease through early detection and modification of underlying mechanisms. Discoveries of genetic mutations causing mitral valve elongation and prolapse have revealed that growth factor signalling and cell migration pathways are regulated by structural molecules in ways that can be modified to limit progression from developmental defects to valve degeneration with clinical complications. Mitral valve enlargement can determine left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and might be stimulated by potentially modifiable biological valvular-ventricular interactions. Mitral valve plasticity also allows adaptive growth in response to ventricular remodelling. However, adverse cellular and mechanobiological processes create relative leaflet deficiency in the ischaemic setting, leading to mitral regurgitation with increased heart failure and mortality. Our approach, which bridges clinicians and basic scientists, enables the correlation of observed disease with cellular and molecular mechanisms, leading to the discovery of new opportunities for improving the natural history of mitral valve disease.

  2. Pump isolation valve

    DOEpatents

    Kinney, Calvin L.; Wetherill, Todd M.

    1983-08-02

    The pump isolation valve provides a means by which the pump may be selectively isolated from the remainder of the coolant system while being compatible with the internal hydraulic arrangement of the pump during normal operation of the pump. The valve comprises a valve cylinder disposed around the pump and adjacent to the last pump diffuser with a turning vane attached to the lower end of the valve cylinder in a manner so as to hydraulically match with the discharge diffuser. The valve cylinder is connected to a drive means for sliding the valve cylinder relative to the diffuser support cylinder so as to block flow in either direction through the discharge diffuser when the valve is in the closed position and to aid in the flow of the coolant from the discharge diffuser by means of the turning vane when the valve is in the open position.

  3. Problem: Mitral Valve Regurgitation

    MedlinePlus

    ... Options • Recovery and Healthy Living Goals • Personal Stories Heart Valve Disease Symptoms Dr. Robert Bonow describes the symptoms that may alert you to heart valve disease. Support Network: You're Not Alone Popular Articles ...

  4. Problem: Heart Valve Regurgitation

    MedlinePlus

    ... Options • Recovery and Healthy Living Goals • Personal Stories Heart Valve Disease Symptoms Dr. Robert Bonow describes the symptoms that may alert you to heart valve disease. Support Network: You're Not Alone Popular Articles ...

  5. Aortic Valve Disease

    MedlinePlus

    ... Ventricle Normal Heart Select Disease To Learn More Aortic Stenosis Aortic Insufficiency Aorta The aorta is the main ... the rest of your body. Aortic Valve In aortic stenosis, the aortic valve becomes narrowed and does not ...

  6. Aortic Valve Stenosis

    MedlinePlus

    ... By Mayo Clinic Staff Aortic valve stenosis — or aortic stenosis — occurs when the heart's aortic valve narrows. This ... pressure may prevent or slow the development of aortic stenosis. Ask your doctor if you need to lower ...

  7. Stemless Ball Valve

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    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.

  8. Aerodynamic Shutoff Valve

    NASA Technical Reports Server (NTRS)

    Horstman, Raymond H.

    1992-01-01

    Aerodynamic flow achieved by adding fixed fairings to butterfly valve. When valve fully open, fairings align with butterfly and reduce wake. Butterfly free to turn, so valve can be closed, while fairings remain fixed. Design reduces turbulence in flow of air in internal suction system. Valve aids in development of improved porous-surface boundary-layer control system to reduce aerodynamic drag. Applications primarily aerospace. System adapted to boundary-layer control on high-speed land vehicles.

  9. Valve technology: A compilation

    NASA Technical Reports Server (NTRS)

    1971-01-01

    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.

  10. 47 CFR 90.492 - One way paging operations in the 806-824/851-869 MHz and 896-901/935-940 MHz bands.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false One way paging operations in the 806-824/851-869 MHz and 896-901/935-940 MHz bands. 90.492 Section 90.492 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Paging...

  11. 47 CFR 90.492 - One way paging operations in the 806-824/851-869 MHz and 896-901/935-940 MHz bands.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false One way paging operations in the 806-824/851-869 MHz and 896-901/935-940 MHz bands. 90.492 Section 90.492 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Paging...

  12. 47 CFR 90.492 - One way paging operations in the 806-824/851-869 MHz and 896-901/935-940 MHz bands.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false One way paging operations in the 806-824/851-869 MHz and 896-901/935-940 MHz bands. 90.492 Section 90.492 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Paging...

  13. 47 CFR 90.492 - One way paging operations in the 806-824/851-869 MHz and 896-901/935-940 MHz bands.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false One way paging operations in the 806-824/851-869 MHz and 896-901/935-940 MHz bands. 90.492 Section 90.492 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Paging...

  14. 47 CFR 90.492 - One way paging operations in the 806-824/851-869 MHz and 896-901/935-940 MHz bands.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false One way paging operations in the 806-824/851-869 MHz and 896-901/935-940 MHz bands. 90.492 Section 90.492 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Paging...

  15. 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 ...

  16. Mitral Valve Prolapse

    PubMed Central

    Rosser, Walter W.

    1992-01-01

    The author discusses the pathophysiology of mitral valve prolapse and provides guidelines to identify and treat low-to high-risk mitral valve prolapse. An approach to diagnosing bacterial endocarditis and its prophylaxis are also discussed. The author reviews mitral valve prolapse syndrome and the risk of sudden death.

  17. Double-Poppet Valve

    NASA Technical Reports Server (NTRS)

    Huber, W. C.

    1984-01-01

    New valve design includes two poppet/seat combinations actuated simultaneously. If one fails, other continues to seal against fluid flow. Valve primarily useful for handling dangerous fluids and lighter and more compact than comparable redundant-valve systems used at present.

  18. Liquid rocket valve assemblies

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The design and operating characteristics of valve assemblies used in liquid propellant rocket engines are discussed. The subjects considered are as follows: (1) valve selection parameters, (2) major design aspects, (3) design integration of valve subassemblies, and (4) assembly of components and functional tests. Information is provided on engine, stage, and spacecraft checkout procedures.

  19. Dump valve assembly

    DOEpatents

    Owen, T.J.

    1984-01-01

    A dump valve assembly comprising a body having a bore defined by a tapered wall and a truncated spherical valve member adapted to seat along a spherical surface portion thereof against said tapered wall. Means are provided for pivoting said valve member between a closed position engagable with said tapered wall and an open position disengaged therefrom.

  20. Well safety valve

    SciTech Connect

    Vinzant, M.B.; Hilts, R.L.; Meaders, M.; Speegle, S.C.

    1984-07-24

    A retrievable well safety valve in a cased well system including a tubing string, a dual packer downhole around the tubing sealing with the casing and submersible pump in the tubing string below the packer. The safety valve controls flow of pumped fluids through the tubing to surface and directs gas flow into the casing annulus above the packer. When the safety valve is landed in cooperating tubing nipples above the packer, separated central annular flow passages are formed for pumped fluids and gas respectively. A ball valve in the central flow passage controls pumped fluid flow therethrough and an annular valve coupled to the ball valve controls gas flow from below the packer through the annular flow passage around and by the ball valve. When the ball valve is in the down and open position, the valve ball member engages a lower seat, which maintains the central and annular flow passages separate and prevents comingling flow of fluids and gas. The coupled valves are held open by pressured fluid from surface and are closed automatically on loss of pressure in their control fluid circuits. When the valves close, a circuit of flow passages for recirculating pumped fluids and gas are opened below the ball valve and the pump may continue operation without overload.

  1. Microblower assisted barometric valve

    DOEpatents

    Rossabi, Joseph; Hyde, Warren K.; Riha, Brian D.; Jackson, Dennis G.; Sappington, Frank

    2005-12-06

    A gas exchange apparatus is provided which provides for both passive fluid flow and blower associated fluid flow through a barometric valve. A battery powered blower is provided which allows for operation of the barometric valve during times when the barometric valve would otherwise be closed, and provides for enhanced volume of gas exchange.

  2. Lock For Valve Stem

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.; Guirguis, Kamal S.

    1991-01-01

    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.

  3. Regional structure-function relationships in mouse aortic valve tissue

    PubMed Central

    Krishnamurthy, Varun K.; Guilak, Farshid; Narmoneva, Daria A.; Hinton, Robert B.

    2010-01-01

    Site-specific biomechanical properties of the aortic valve play an important role in native valve function, and alterations in these properties may reflect mechanisms of degeneration and disease. Small animals such as targeted mutagenesis mice provide a powerful approach to model human valve disease pathogenesis; however, physical mechanical testing in small animals is limited by valve tissue size. Aortic valves are comprised of highly organized extracellular matrix compartmentalized in cusp and annulus regions, which have different functions. The objective of this study was to measure regional mechanical properties of mouse aortic valve tissue using a modified micropipette aspiration technique. Aortic valves were isolated from juvenile, adult and aged adult C57BL/6 wild type mice. Tissue tensile stiffness was determined for annulus and cusp regions using a half-space punch model. Stiffness for the annulus region was significantly higher compared to the cusp region at all stages. Further, aged adult valve tissue had decreased stiffness in both the cusp and annulus. Quantitative histochemical analysis revealed a collagen-rich annulus and a proteoglycan-rich cusp at all stages. In aged adult valves, there was proteoglycan infiltration of the annulus hinge, consistent with observed mechanical differences over time. These findings indicate that valve tissue biomechanical properties vary in wild type mice in a region-specific and age-related manner. The micropipette aspiration technique provides a promising approach for studies of valve structure and function in small animal models, such as transgenic mouse models of valve disease. PMID:20863504

  4. Mitral Valve Annuloplasty

    PubMed Central

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

    2012-01-01

    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

  5. How Is Mitral Valve Prolapse Treated?

    MedlinePlus

    ... page from the NHLBI on Twitter. How Is Mitral Valve Prolapse Treated? Most people who have mitral valve ... all hospitals offer this method. Valve Repair and Valve Replacement In mitral valve surgery, the valve is repaired or replaced. ...

  6. Main Oxidizer Valve Design

    NASA Technical Reports Server (NTRS)

    Addona, Brad; Eddleman, David

    2015-01-01

    A developmental Main Oxidizer Valve (MOV) was designed by NASA-MSFC using additive manufacturing processes. The MOV is a pneumatically actuated poppet valve to control the flow of liquid oxygen to an engine's injector. A compression spring is used to return the valve to the closed state when pneumatic pressure is removed from the valve. The valve internal parts are cylindrical in shape, which lends itself to traditional lathe and milling operations. However, the valve body represents a complicated shape and contains the majority of the mass of the valve. Additive manufacturing techniques were used to produce a part that optimized mass and allowed for design features not practical with traditional machining processes.

  7. CAM operated fuel valve

    SciTech Connect

    Kelly, S.T.; Katchka, J.R.

    1991-09-03

    This patent describes improvement in a fuel control valve construction comprising a housing means having an inlet means adapted to be interconnected to a fuel source and a main outlet means adapted to be interconnected to a main burner means, the housing means having a main valve seat for interconnecting the inlet means with the main outlet means, the housing means having a movable main valve member for opening and closing the main valve seat, the housing means having a movable lever operatively associated with the main valve member and having a manually operable actuator means for controlling the operating positions of the lever, the lever having an intermediate cam follower portion and opposed ends disposed on each side of the cam follower portion with one end of the opposed ends being pivotally mounted to the housing means and with the other end of the opposed ends for operating the main valve member, the housing means having biasing means operatively interconnected to the lever to tend to pivot the lever in one direction that opens the main valve member away from its the main valve seat. The improvement comprises; the housing means has a thermostatically controlled means that is operatively associated with the lever and is adapted to engage and hold the lever in a position wherein the main valve member is in a closed condition against its the main valve seat when the thermostatically controlled means is in one operating condition thereof and the actuator means is in the on condition thereof.

  8. Valve selection in aortic valve endocarditis

    PubMed Central

    Zubrytska, Yana

    2016-01-01

    Aortic prosthetic valve endocarditis (PVE) is a potentially life-threatening disease. Mortality and incidence of infective endocarditis have been reduced in the past 30 years. Medical treatment of aortic PVE may be successful in patients who have a prompt response after antibiotic treatment and who do not have prosthetic dysfunction. In advanced stages, antibiotic therapy alone is insufficient to control the disease, and surgical intervention is necessary. Surgical treatment may be lifesaving, but it is still associated with considerable morbidity and mortality. The aim of surgery is to perform a radical excision of all infected and necrotic tissue, reconstruction of the left ventricle outflow tract, and replacement of the aortic valve. There is no unanimous consensus on which is the optimal prosthesis to implant in this context, and several surgical techniques have been suggested. We aim to analyze the efficacy of the surgical treatment and discuss the issue of valve selection in patients with aortic valve endocarditis. PMID:27785132

  9. Guide to prosthetic cardiac valves

    SciTech Connect

    Morse, D.; Steiner, R.M.; Fernandez, J.

    1985-01-01

    This book contains 10 chapters. Some of the chapter titles are: The development of artificial heart valves: Introduction and historical perspective; The radiology of prosthetic heart valves; The evaluation of patients for prosthetic valve implantation; Pathology of cardiac valve replacement; and Bioengineering of mechanical and biological heart valve substitutes.

  10. What Is Heart Valve Disease?

    MedlinePlus

    ... flow properly. Acquired heart valve disease usually involves aortic or mitral valves. Although the valves are normal at first, problems develop over time. Both congenital and acquired heart valve disease can cause stenosis or backflow. Outlook Many people have heart valve ...

  11. A molecular-sized tunnel-porous crystal with a ratchet gear structure and its one-way guest-molecule transportation property

    NASA Astrophysics Data System (ADS)

    Kataoka, Keisuke; Yasumoto, Tetsuaki; Manabe, Yousuke; Sato, Hiroyasu; Yamano, Akihito; Katagiri, Toshimasa

    2013-01-01

    An anisotropic tunnel microporous crystal was prepared. Active transportation of anthracene as a guest molecule in the anisotropic tunnels was observed. The direction of anthracene movement implies that the anisotropic tunnel did not work as a flap-check valve. The direction of the movement was consistent with that caused by a Brownian ratchet.An anisotropic tunnel microporous crystal was prepared. Active transportation of anthracene as a guest molecule in the anisotropic tunnels was observed. The direction of anthracene movement implies that the anisotropic tunnel did not work as a flap-check valve. The direction of the movement was consistent with that caused by a Brownian ratchet. Electronic supplementary information (ESI) available. CCDC reference numbers 837539 and 837540. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c2nr30880k

  12. Cryogenic Cam Butterfly Valve

    NASA Technical Reports Server (NTRS)

    McCormack, Kenneth J. (Inventor)

    2016-01-01

    A cryogenic cam butterfly valve has a body that includes an axially extending fluid conduit formed there through. A disc lug is connected to a back side of a valve disc and has a circular bore that receives and is larger than a cam of a cam shaft. The valve disc is rotatable for a quarter turn within the body about a lug axis that is offset from the shaft axis. Actuating the cam shaft in the closing rotational direction first causes the camming side of the cam of the cam shaft to rotate the disc lug and the valve disc a quarter turn from the open position to the closed position. Further actuating causes the camming side of the cam shaft to translate the valve disc into sealed contact with the valve seat. Opening rotational direction of the cam shaft reverses these motions.

  13. Minimally invasive valve surgery.

    PubMed

    Woo, Y Joseph; Seeburger, Joerg; Mohr, Friedrich W

    2007-01-01

    As alternatives to standard sternotomy, surgeons have developed innovative, minimally invasive approaches to conducting valve surgery. Through very small skin incisions and partial upper sternal division for aortic valve surgery and right minithoracotomy for mitral surgery, surgeons have become adept at performing complex valve procedures. Beyond cosmetic appeal, apparent benefits range from decreased pain and bleeding to improved respiratory function and recovery time. The large retrospective studies and few small prospective randomized studies are herein briefly summarized. The focus is then directed toward describing specific intraoperative technical details in current clinical use, covering anesthetic preparation, incision, mediastinal access, cardiovascular cannulation, valve exposure, and valve reconstruction. Finally, unique situations such as pulmonic valve surgery, reoperations, beating heart surgery, and robotics are discussed.

  14. Intelligent Flow Control Valve

    NASA Technical Reports Server (NTRS)

    Kelley, Anthony R (Inventor)

    2015-01-01

    The present invention is an intelligent flow control valve which may be inserted into the flow coming out of a pipe and activated to provide a method to stop, measure, and meter flow coming from the open or possibly broken pipe. The intelligent flow control valve may be used to stop the flow while repairs are made. Once repairs have been made, the valve may be removed or used as a control valve to meter the amount of flow from inside the pipe. With the addition of instrumentation, the valve may also be used as a variable area flow meter and flow controller programmed based upon flowing conditions. With robotic additions, the valve may be configured to crawl into a desired pipe location, anchor itself, and activate flow control or metering remotely.

  15. JenaValve.

    PubMed

    Treede, Hendrik; Rastan, Ardawan; Ferrari, Markus; Ensminger, Stephan; Figulla, Hans-Reiner; Mohr, Friedrich-Wilhelm

    2012-09-01

    The JenaValve is a next-generation TAVI device which consists of a well-proven porcine root valve mounted on a low-profile nitinol stent. Feeler guided positioning and clip fixation on the diseased leaflets allow for anatomically correct implantation of the device without rapid pacing. Safety and efficacy of transapical aortic valve implantation using the JenaValve were evaluated in a multicentre prospective study that showed good short and midterm results. The valve was CE-mark released in Europe in September 2011. A post-market registry ensures on-going and prospective data collection in "real-world" patients. The transfemoral JenaValve delivery system will be evaluated in a first-in-man study in the near future.

  16. Development of myoelectric control type speaking valve with low flow resistance

    NASA Astrophysics Data System (ADS)

    Ooe, Katsutoshi; Sakurai, Kohei; Mimaki, Shinya

    2015-12-01

    We aimed to develop welfare devices for patients with phonation disorder. One of these devices is the electrical controltype speaking valve system. The conventional speaking valves have one-way valve architecture, they open when the user breathes in, and they close when user breathes out and produce voices. This type is very simple and tough, but some users feel closeness in case of exhalation without phonation. This problem is caused by its mechanism what can not be controlled by user's will. Therefore, we proposed an electrical control-type speaking valve system to resolve this problem. This valve is controlled by neck myoelectric signal of sternohyoid muscle. From our previous report, it was clarified that this valve had better performance about easy-to-breath. Furthermore, we proposed the compact myoelectric control-type speaking valve system. The new-type speaking valve was enough small to attach the human body, and its opening area is larger than that of conventional one. Additionally, we described the improvement of flow channel shape by using of FEM analysis. According to the result of the analysis, it was clarified that the shape-improved speaking valve gets the low flow resistance channel in case of inspiration. In this report, we tried to make the flow resistance lower by the shape of current plates, in case of both inspiration and exhalation. From the result of FEM analysis, our speaking valve could get better flow channel than older one.

  17. Computational analysis of an aortic valve jet

    NASA Astrophysics Data System (ADS)

    Shadden, Shawn C.; Astorino, Matteo; Gerbeau, Jean-Frédéric

    2009-11-01

    In this work we employ a coupled FSI scheme using an immersed boundary method to simulate flow through a realistic deformable, 3D aortic valve model. This data was used to compute Lagrangian coherent structures, which revealed flow separation from the valve leaflets during systole, and correspondingly, the boundary between the jet of ejected fluid and the regions of separated, recirculating flow. Advantages of computing LCS in multi-dimensional FSI models of the aortic valve are twofold. For one, the quality and effectiveness of existing clinical indices used to measure aortic jet size can be tested by taking advantage of the accurate measure of the jet area derived from LCS. Secondly, as an ultimate goal, a reliable computational framework for the assessment of the aortic valve stenosis could be developed.

  18. Aortic or Mitral Valve Replacement With the Biocor and Biocor Supra

    ClinicalTrials.gov

    2016-03-09

    Aortic Valve Insufficiency; Aortic Valve Regurgitation; Aortic Valve Stenosis; Aortic Valve Incompetence; Mitral Valve Insufficiency; Mitral Valve Regurgitation; Mitral Valve Stenosis; Mitral Valve Incompetence

  19. [Modern mitral valve surgery].

    PubMed

    Bothe, W; Beyersdorf, F

    2016-04-01

    At the beginning of the 20th century, Cutler and Levine performed the first successful surgical treatment of a stenotic mitral valve, which was the only treatable heart valve defect at that time. Mitral valve surgery has evolved significantly since then. The introduction of the heart-lung machine in 1954 not only reduced the surgical risk, but also allowed the treatment of different mitral valve pathologies. Nowadays, mitral valve insufficiency has become the most common underlying pathomechanism of mitral valve disease and can be classified into primary and secondary mitral insufficiency. Primary mitral valve insufficiency is mainly caused by alterations of the valve (leaflets and primary order chords) itself, whereas left ventricular dilatation leading to papillary muscle displacement and leaflet tethering via second order chords is the main underlying pathomechanism for secondary mitral valve regurgitation. Valve reconstruction using the "loop technique" plus annuloplasty is the surgical strategy of choice and normalizes life expectancy in patients with primary mitral regurgitation. In patients with secondary mitral regurgitation, implanting an annuloplasty is not superior to valve replacement and results in high rates of valve re-insufficiency (up to 30 % after 3 months) due to ongoing ventricular dilatation. In order to improve repair results in these patients, we add a novel subvalvular technique (ring-noose-string) to the annuloplasty that aims to prevent ongoing ventricular remodeling and re-insufficiency. In modern mitral surgery, a right lateral thoracotomy is the approach of choice with excellent repair and cosmetic results.

  20. Passively actuated valve

    SciTech Connect

    Modro, S. Michael; Ougouag, Abderrafi M.

    2005-09-20

    A passively actuated valve for isolating a high pressure zone from a low pressure zone and discontinuing the isolation when the pressure in the high pressure zone drops below a preset threshold. If the pressure in the high pressure zone drops below the preset threshold, the valve opens and allows flow from the high pressure zone to the low pressure zone. The valve remains open allowing pressure equalization and back-flow should a pressure inversion between the two pressure zone occur.

  1. Transventricular mitral valve operations.

    PubMed

    Joseph Woo, Y; McCormick, Ryan C

    2011-10-01

    We report transventricular mitral valve operations in 2 patients with severe mitral regurgitation and postinfarction left ventricular rupture and pseudoaneurysm. The first patient had direct papillary muscle involvement necessitating replacement of the mitral valve. The second patient had indirect mitral involvement allowing for placement of an atrial mitral annuloplasty ring via the left ventricle. Both patients showed no mitral valve regurgitation after replacement or repair and had uneventful postoperative recoveries. These cases demonstrate a feasible, alternative, transventricular approach to mitral valve replacement and repair.

  2. Compact gate valve

    DOEpatents

    Bobo, Gerald E.

    1977-01-01

    This invention relates to a double-disc gate valve which is compact, comparatively simple to construct, and capable of maintaining high closing pressures on the valve discs with low frictional forces. The valve casing includes axially aligned ports. Mounted in the casing is a sealed chamber which is pivotable transversely of the axis of the ports. The chamber contains the levers for moving the valve discs axially, and an actuator for the levers. When an external drive means pivots the chamber to a position where the discs are between the ports and axially aligned therewith, the actuator for the levers is energized to move the discs into sealing engagement with the ports.

  3. Magnetic Check Valve

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    Poppet in proposed check valve restored to closed condition by magnetic attraction instead of spring force. Oscillations suppressed, with consequent reduction of wear. Stationary magnetic disk mounted just upstream of poppet, also containing magnet. Valve body nonmagnetic. Forward pressure or flow would push poppet away from stationary magnetic disk so fluid flows easily around poppet. Stop in valve body prevents poppet from being swept away. When flow stopped or started to reverse, magnetic attraction draws poppet back to disk. Poppet then engages floating O-ring, thereby closing valve and preventing reverse flow. Floating O-ring facilitates sealing at low loads.

  4. Solid handling valve

    DOEpatents

    Williams, William R.

    1979-01-01

    The present invention is directed to a solids handling valve for use in combination with lock hoppers utilized for conveying pulverized coal to a coal gasifier. The valve comprises a fluid-actuated flow control piston disposed within a housing and provided with a tapered primary seal having a recessed seat on the housing and a radially expandable fluid-actuated secondary seal. The valve seals are highly resistive to corrosion, erosion and abrasion by the solids, liquids, and gases associated with the gasification process so as to minimize valve failure.

  5. Engine valve driving apparatus

    SciTech Connect

    Masuda, S.; Uesugi, T.; Oda, H.

    1989-01-03

    An engine valve driving apparatus for an internal combustion engine having a cam driven engine valve is described. It consists of a camshaft rotatable in synchronism with rotation of a crankshaft of an engine and a movable cam member supported by the camshaft for axial movement and prevented from turning relative to the camshaft. The movable cam member can be axially shifted between an operative position wherein the cam member is cooperative with a member of the engine valve so as to cause an operation of the engine valve and an inoperative position wherein the cam member is out of cooperation with the member.

  6. Modeling the Mitral Valve

    NASA Astrophysics Data System (ADS)

    Kaiser, Alexander

    2016-11-01

    The mitral valve is one of four valves in the human heart. The valve opens to allow oxygenated blood from the lungs to fill the left ventricle, and closes when the ventricle contracts to prevent backflow. The valve is composed of two fibrous leaflets which hang from a ring. These leaflets are supported like a parachute by a system of strings called chordae tendineae. In this talk, I will describe a new computational model of the mitral valve. To generate geometry, general information comes from classical anatomy texts and the author's dissection of porcine hearts. An MRI image of a human heart is used to locate the tips of the papillary muscles, which anchor the chordae tendineae, in relation to the mitral ring. The initial configurations of the valve leaflets and chordae tendineae are found by solving solving an equilibrium elasticity problem. The valve is then simulated in fluid (blood) using the immersed boundary method over multiple heart cycles in a model valve tester. We aim to identify features and mechanisms that influence or control valve function. Support from National Science Foundation, Graduate Research Fellowship Program, Grant DGE 1342536.

  7. What Causes Heart Valve Disease?

    MedlinePlus

    ... page from the NHLBI on Twitter. What Causes Heart Valve Disease? Heart conditions and other disorders, age-related changes, ... valve disease. Other Conditions and Factors Linked to Heart Valve Disease Many other conditions and factors are linked to ...

  8. Options for Heart Valve Replacement

    MedlinePlus

    ... which may include human or animal donor tissue) Ross Procedure — “Borrowing” your healthy valve and moving it ... Considerations for Surgery Medications Valve Repair Valve Replacement - Ross Procedure - Newer Surgery Options - What is TAVR? - Types ...

  9. The effect of nasal speaking valve on the speech under experimental velopharyngeal incompetence condition.

    PubMed

    Suwaki, M; Nanba, K; Ito, E; Kumakura, I; Minagi, S

    2008-05-01

    Velopharyngeal incompetence (VPI) is a contributing factor to speech disorders, frequently accompanying disorders, such as cleft palate, congenital paralysis of the soft palate, and cerebrovascular disease. For the treatment of these types of dysarthria, a Nasal Speaking Valve (NSV), which regulates nasal emission utilizing one-way valve, has been reported to be effective. As the unpleasantness while wearing the NSV was less than that with the conventional Palatal Lift Prosthesis, the NSV could be worn for a longer period of time. As NSV is inserted into the nostrils, this device could easily be provided for edentulous patients. This study aimed to evaluate the effect of NSV on experimentally induced VPI condition. Intelligibility of monosyllabic speech, intelligibility of conversational speech, nasalance score and acoustic analysis were used to evaluate the effect of NSV. Local infiltration anaesthesia was achieved to the area of levator veli palatini muscle and tensor veli palatine muscle of seven adult male subjects. In all subjects, remarkable suppression of the soft palate movement could be observed after the local infiltration anesthesia. Although the utterance supported by NSV under the experimentally induced VPI condition was less natural than the normal utterance, the intelligibility was markedly improved by the device. From the results of this study, the acoustic properties of NSV on the pure VPI condition, which was enabled by the newly established experimental induction, were revealed. This experimental model was also proved to provide a basis for the improvement in the treatment modalities for VPI.

  10. A magnetically driven PDMS micropump with microball valves.

    PubMed

    McDonald, Scott; Pan, Tingrui; Ziaie, Babak

    2004-01-01

    We present a novel robust PDMS membrane micropump with two one-way microball valves for biomedical applications. The actuating membrane is driven by magnetic force of two miniature permanent magnets. The micropump consists of two PDMS layers, one holding the microball valves and actuating chamber and the second holding the top magnet and covering the chamber and microvalves. A simple approach is used to fabricate a high performance microball valve using an embedded Teflon/sup trade mark/ microtube. A small DC motor (6mm in diameter and 15mm in length) with two permanent magnetic discs (NdFeB) mounted on its shaft is used to actuate the membrane-mounted magnet. This configuration yields a large pumping rate with very low power consumption. Maximum pumping rate of 260muL/min was achieved at the input power of 21mW, the highest pumping rate reported in the literature for micropumps at such power consumption.

  11. One-way quantum computing with arbitrarily large time-frequency continuous-variable cluster states from a single optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Alexander, Rafael N.; Wang, Pei; Sridhar, Niranjan; Chen, Moran; Pfister, Olivier; Menicucci, Nicolas C.

    2016-09-01

    One-way quantum computing is experimentally appealing because it requires only local measurements on an entangled resource called a cluster state. Record-size, but nonuniversal, continuous-variable cluster states were recently demonstrated separately in the time and frequency domains. We propose to combine these approaches into a scalable architecture in which a single optical parametric oscillator and simple interferometer entangle up to (3 ×103 frequencies) × (unlimited number of temporal modes) into a computationally universal continuous-variable cluster state. We introduce a generalized measurement protocol to enable improved computational performance on this entanglement resource.

  12. Generation of high-fidelity four-photon cluster state and quantum-domain demonstration of one-way quantum computing.

    PubMed

    Tokunaga, Yuuki; Kuwashiro, Shin; Yamamoto, Takashi; Koashi, Masato; Imoto, Nobuyuki

    2008-05-30

    We experimentally demonstrate a simple scheme for generating a four-photon entangled cluster state with fidelity over 0.860+/-0.015. We show that the fidelity is high enough to guarantee that the produced state is distinguished from Greenberger-Horne-Zeilinger, W, and Dicke types of genuine four-qubit entanglement. We also demonstrate basic operations of one-way quantum computing using the produced state and show that the output state fidelities surpass classical bounds, which indicates that the entanglement in the produced state essentially contributes to the quantum operation.

  13. Late Paravalvular Aortic Regurgitation: Migration of the Valve or Late Recoil?

    PubMed

    Karimi, Ashkan; Pourafshar, Negiin; Park, Ki E; Choi, Calvin Y; Mogali, Kiran; Stinson, Wade W; Manning, Eddie W; Bavry, Anthony A

    2017-01-02

    A 79-year-old man underwent trans-catheter aortic valve replacement for symptomatic severe aortic stenosis with a 26-mm Edwards SAPIEN XT valve. Immediately after valve deployment there was moderate amount of paravalvular leak. Post-dilation was performed with an additional 2 cc of volume, and the paravalvular leak was reduced to trace. Nine months later, trans-thoracic echocardiography revealed moderate to severe paravalvular leak and possible aortic migration of the valve. The patient was brought back for the treatment of the paravalvular leak which was suspected to be due to valve migration. However, fluoroscopy and trans-esophageal echocardiography showed good valve position. Measurement of late valve recoil in the Coplanar view using cine-angiographic analysis software showed that the lower third of the valve had the greatest late recoil (-1.74 mm, 6.55%), which presumably accounted for the progression of the paravalvular leak. Valve-in-valve trans-catheter aortic valve replacement was performed with a 26-mm SAPIEN 3 valve and the paravalvular leak was reduced to trace. This case displays late recoil as a likely mechanism for development of paravalvular leak after SAPIEN XT valve implantation. Our case illustrates that late recoil needs to be systematically evaluated in future studies, especially when trans-catheter aortic valve replacement is being expanded to lower risk and younger patients for whom the longevity and long-term performance of these valves is of critical importance.

  14. Valve mechanisms for at least two simultaneously actuable valves

    SciTech Connect

    Heimburg, F.

    1989-02-21

    This patent describes a valve gear for at least two valves of an internal combustion engine to be operated simultaneously on longitudinal axes, wherein the valve gear comprises a thrust device which is common to all valves and displaceable on an axis by a cam shaft and against which the valves abut by their valve stems to that displacement of the thrust device causes corresponding displacement of the valves, characterized in that the camshaft includes a single cam that is seated on the thrust device eccentrically relative to its axis causing rotation of the thrust device about its axis. When the thrust device is displaced, the thrust device is axially symmetrical, and the valve stems each abut against the thrust device at positions centered on points offset from the longitudinal axes of the valves causing rotation of the valves about their longitudinal axis when the valves are displaced.

  15. Understanding Heart Valve Problems and Causes

    MedlinePlus

    ... affecting the aortic valve, and can lead to aortic stenosis . Mediastinal radiation therapy (radiation to the chest) – Studies ... Disease "Innocent" Heart Murmur Problem: Valve Stenosis - Problem: Aortic Valve Stenosis - Problem: Mitral Valve Stenosis - Problem: Tricuspid Valve Stenosis - ...

  16. How Is Heart Valve Disease Treated?

    MedlinePlus

    ... and replacing it with a man-made or biological valve. Biological valves are made from pig, cow, or human ... the valve. Man-made valves last longer than biological valves and usually don’t have to be ...

  17. Terahertz polarization converter and one-way transmission based on double-layer magneto-plasmonics of magnetized InSb.

    PubMed

    Fan, Fei; Xu, Shi-Tong; Wang, Xiang-Hui; Chang, Sheng-Jiang

    2016-11-14

    In this work, we investigate the nonreciprocal circular dichroism for terahertz (THz) waves in magnetized InSb by the theoretical calculation and numerical simulation, which indicates that longitudinally magnetized InSb can be applied to the circular polarizer and nonreciprocal one-way transmission for the circular polarization THz waves. Furthermore, we propose a double-layer magnetoplasmonics based on the longitudinally magnetized InSb, and find two MO enhancement mechanisms in this device: the magneto surface plasmon resonance on the InSb-metal surface and Fabry-Pérot resonances between two orthogonal metallic gratings. These two resonance mechanisms enlarge the MO polarization rotation and greatly reduce the external magnetic field below 0.1T. The one-way transmission and perfect linear polarization conversion can be realized over 70dB, of which the transmittance can be modulated from 0 to 80% when the weak magnetic field changes from 0 to 0.1T under the low temperature around 200K. This magnetoplasmonic device has broad potential as a THz isolator, modulator, polarization convertor, and filter in the THz application systems.

  18. Improved one-way hash chain and revocation polynomial-based self-healing group key distribution schemes in resource-constrained wireless networks.

    PubMed

    Chen, Huifang; Xie, Lei

    2014-12-18

    Self-healing group key distribution (SGKD) aims to deal with the key distribution problem over an unreliable wireless network. In this paper, we investigate the SGKD issue in resource-constrained wireless networks. We propose two improved SGKD schemes using the one-way hash chain (OHC) and the revocation polynomial (RP), the OHC&RP-SGKD schemes. In the proposed OHC&RP-SGKD schemes, by introducing the unique session identifier and binding the joining time with the capability of recovering previous session keys, the problem of the collusion attack between revoked users and new joined users in existing hash chain-based SGKD schemes is resolved. Moreover, novel methods for utilizing the one-way hash chain and constructing the personal secret, the revocation polynomial and the key updating broadcast packet are presented. Hence, the proposed OHC&RP-SGKD schemes eliminate the limitation of the maximum allowed number of revoked users on the maximum allowed number of sessions, increase the maximum allowed number of revoked/colluding users, and reduce the redundancy in the key updating broadcast packet. Performance analysis and simulation results show that the proposed OHC&RP-SGKD schemes are practical for resource-constrained wireless networks in bad environments, where a strong collusion attack resistance is required and many users could be revoked.

  19. Role of Channel Lysines and the “Push Through a One-Way Valve” Mechanism of the Viral DNA Packaging Motor

    PubMed Central

    Fang, Huaming; Jing, Peng; Haque, Farzin; Guo, Peixuan

    2012-01-01

    Linear double-stranded DNA (dsDNA) viruses package their genomes into preformed protein shells via nanomotors using ATP as an energy source. The central hub of the bacteriophage ϕ29 DNA-packaging motor contains a 3.6-nm channel for dsDNA to enter during packaging and to exit during infection. The negatively charged interior channel wall is decorated with a total of 48 positively charged lysine residues displayed as four 12-lysine rings from the 12 gp10 subunits that enclose the channel. The standard notion derived from many models is that these uniquely arranged, positively charged rings play active roles in DNA translocation through the channel. In this study, we tested this prevailing view by examining the effect of mutating these basic lysines to alanines, and assessing the impact of altering the pH environment. Unexpectedly, mutating these basic lysine residues or changing the pH to 4 or 10, which could alter the charge of lysines, did not measurably impair DNA translocation or affect the one-way traffic property of the channel. The results support our recent findings regarding the dsDNA packaging mechanism known as the “push through a one-way valve”. PMID:22225806

  20. Improved One-Way Hash Chain and Revocation Polynomial-Based Self-Healing Group Key Distribution Schemes in Resource-Constrained Wireless Networks

    PubMed Central

    Chen, Huifang; Xie, Lei

    2014-01-01

    Self-healing group key distribution (SGKD) aims to deal with the key distribution problem over an unreliable wireless network. In this paper, we investigate the SGKD issue in resource-constrained wireless networks. We propose two improved SGKD schemes using the one-way hash chain (OHC) and the revocation polynomial (RP), the OHC&RP-SGKD schemes. In the proposed OHC&RP-SGKD schemes, by introducing the unique session identifier and binding the joining time with the capability of recovering previous session keys, the problem of the collusion attack between revoked users and new joined users in existing hash chain-based SGKD schemes is resolved. Moreover, novel methods for utilizing the one-way hash chain and constructing the personal secret, the revocation polynomial and the key updating broadcast packet are presented. Hence, the proposed OHC&RP-SGKD schemes eliminate the limitation of the maximum allowed number of revoked users on the maximum allowed number of sessions, increase the maximum allowed number of revoked/colluding users, and reduce the redundancy in the key updating broadcast packet. Performance analysis and simulation results show that the proposed OHC&RP-SGKD schemes are practical for resource-constrained wireless networks in bad environments, where a strong collusion attack resistance is required and many users could be revoked. PMID:25529204

  1. Inhibitory role of Notch1 in calcific aortic valve disease.

    PubMed

    Acharya, Asha; Hans, Chetan P; Koenig, Sara N; Nichols, Haley A; Galindo, Cristi L; Garner, Harold R; Merrill, Walter H; Hinton, Robert B; Garg, Vidu

    2011-01-01

    Aortic valve calcification is the most common form of valvular heart disease, but the mechanisms of calcific aortic valve disease (CAVD) are unknown. NOTCH1 mutations are associated with aortic valve malformations and adult-onset calcification in families with inherited disease. The Notch signaling pathway is critical for multiple cell differentiation processes, but its role in the development of CAVD is not well understood. The aim of this study was to investigate the molecular changes that occur with inhibition of Notch signaling in the aortic valve. Notch signaling pathway members are expressed in adult aortic valve cusps, and examination of diseased human aortic valves revealed decreased expression of NOTCH1 in areas of calcium deposition. To identify downstream mediators of Notch1, we examined gene expression changes that occur with chemical inhibition of Notch signaling in rat aortic valve interstitial cells (AVICs). We found significant downregulation of Sox9 along with several cartilage-specific genes that were direct targets of the transcription factor, Sox9. Loss of Sox9 expression has been published to be associated with aortic valve calcification. Utilizing an in vitro porcine aortic valve calcification model system, inhibition of Notch activity resulted in accelerated calcification while stimulation of Notch signaling attenuated the calcific process. Finally, the addition of Sox9 was able to prevent the calcification of porcine AVICs that occurs with Notch inhibition. In conclusion, loss of Notch signaling contributes to aortic valve calcification via a Sox9-dependent mechanism.

  2. PETOOL: MATLAB-based one-way and two-way split-step parabolic equation tool for radiowave propagation over variable terrain

    NASA Astrophysics Data System (ADS)

    Ozgun, Ozlem; Apaydin, Gökhan; Kuzuoglu, Mustafa; Sevgi, Levent

    2011-12-01

    A MATLAB-based one-way and two-way split-step parabolic equation software tool (PETOOL) has been developed with a user-friendly graphical user interface (GUI) for the analysis and visualization of radio-wave propagation over variable terrain and through homogeneous and inhomogeneous atmosphere. The tool has a unique feature over existing one-way parabolic equation (PE)-based codes, because it utilizes the two-way split-step parabolic equation (SSPE) approach with wide-angle propagator, which is a recursive forward-backward algorithm to incorporate both forward and backward waves into the solution in the presence of variable terrain. First, the formulation of the classical one-way SSPE and the relatively-novel two-way SSPE is presented, with particular emphasis on their capabilities and the limitations. Next, the structure and the GUI capabilities of the PETOOL software tool are discussed in detail. The calibration of PETOOL is performed and demonstrated via analytical comparisons and/or representative canonical tests performed against the Geometric Optic (GO) + Uniform Theory of Diffraction (UTD). The tool can be used for research and/or educational purposes to investigate the effects of a variety of user-defined terrain and range-dependent refractivity profiles in electromagnetic wave propagation. Program summaryProgram title: PETOOL (Parabolic Equation Toolbox) Catalogue identifier: AEJS_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJS_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 143 349 No. of bytes in distributed program, including test data, etc.: 23 280 251 Distribution format: tar.gz Programming language: MATLAB (MathWorks Inc.) 2010a. Partial Differential Toolbox and Curve Fitting Toolbox required Computer: PC Operating system: Windows XP and

  3. Temperature-Operated Valve

    NASA Technical Reports Server (NTRS)

    Morrison, Andrew D.

    1994-01-01

    Bimetallic valve stem positions orifice at end of inner pipe orifice so liquid flows to outlet when temperature lies within small range of preset value. If liquid too cold or too hot, orifices misaligned and liquid returned to source. Such as in shower, valve prevents outflow of dangerously hot or uncomfortably cold water.

  4. Mitral valve surgery - open

    MedlinePlus

    ... Saunders; 2012:chap 61. Otto CM, Bonow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ... Editorial team. Related MedlinePlus Health Topics Heart Surgery Heart Valve Diseases Mitral Valve Prolapse Browse the Encyclopedia A.D. ...

  5. Minimally invasive valve surgery.

    PubMed

    Woo, Y Joseph

    2009-08-01

    Traditional cardiac valve replacement surgery is being rapidly supplanted by innovative, minimally invasive approaches toward the repair of these valves. Patients are experiencing benefits ranging from less bleeding and pain to faster recovery and greater satisfaction. These operations are proving to be safe, highly effective, and durable, and their use will likely continue to increase and become even more widely applicable.

  6. Linear motion valve

    NASA Technical Reports Server (NTRS)

    Chandler, J. A. (Inventor)

    1985-01-01

    The linear motion valve is described. The valve spool employs magnetically permeable rings, spaced apart axially, which engage a sealing assembly having magnetically permeable pole pieces in magnetic relationship with a magnet. The gap between the ring and the pole pieces is sealed with a ferrofluid. Depletion of the ferrofluid is minimized.

  7. Valve for abrasive material

    DOEpatents

    Gardner, Harold S.

    1982-01-01

    A ball valve assembly for controlling the flow of abrasive particulates including an enlarged section at the bore inlet and an enlarged section at the bore outlet. A refractory ceramic annular deflector is positioned in each of the enlarged sections, substantially extending the useful life of the valve.

  8. Space Vehicle Valve System

    NASA Technical Reports Server (NTRS)

    Kelley, Anthony R. (Inventor); Lindner, Jeffrey L. (Inventor)

    2014-01-01

    The present invention is a space vehicle valve system which controls the internal pressure of a space vehicle and the flow rate of purged gases at a given internal pressure and aperture site. A plurality of quasi-unique variable dimension peaked valve structures cover the purge apertures on a space vehicle. Interchangeable sheet guards configured to cover valve apertures on the peaked valve structure contain a pressure-activated surface on the inner surface. Sheet guards move outwardly from the peaked valve structure when in structural contact with a purge gas stream flowing through the apertures on the space vehicle. Changing the properties of the sheet guards changes the response of the sheet guards at a given internal pressure, providing control of the flow rate at a given aperture site.

  9. ULTRA HIGH VACUUM VALVE

    DOEpatents

    Fry, W.A.

    1962-05-29

    A valve for high vacuum applications such as the CStellarator where chamber pressures as low as 2 x 10/sup -10/ mm Hg are necessary is designed with a line-of-sight path through the valve for visual inspection of the contents of reactants in such chambers. The valve comprises a turnable resilient metal ball having an aperture therethrough, means for selectively turning the ball to rotate the axis of its line-of-sight path, and soft, deformable opposing orifices that are movable relatively toward said ball to seal with opposite ball surfaces upon said movement of said axis of said line-of-sight path. The valve also includes a bellows seal connected between said orifices and internal actuating means that eliminates the requirement for gasketed turnable valve closing stems. (AEC)

  10. Boston Scientific Lotus valve.

    PubMed

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

    2012-09-01

    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.

  11. Cavitation dynamics of mechanical heart valve prostheses.

    PubMed

    Lee, C S; Chandran, K B; Chen, L D

    1994-10-01

    Nine different mechanical mitral heart valves were chosen in order to study cavitation dynamics in detail in an in vitro flow system simulating a single event of mitral valve closure. The transvalvular pressure (ventricular minus atrial pressure) rise rate averaged during the valve closing period was used as an index of the loading rate. A series of photographs in the vicinity of the inflow surface of the valve were attempted during the bubble appearance period using a stroboscopic visualization technique. The in vitro study revealed three sources of cavitation initiation in the design of the mechanical heart valves tested: stop (seat stop or seating lip), inflow strut, and clearance (gap formed between the occluder and the housing or between the two occluders in the closed position). Among these, the occluder stop design was the most critical to cavitation since all valves having the stop at the edge of the major orifice area showed a higher intensity of cavitation and threshold loading rates below the estimated normal physiological value. The analysis of bubble locations and dynamics led us to propose that the fluid squeezing effect between the occluder and the stop in the housing and the streamline contraction effect along the clearance are factors responsible for cavitation incipience.

  12. Intermittent stuck valve after aortic valve replacement with a mechanical valve

    PubMed Central

    Luo, Wenzong; Wang, Xinxin; Li, Jing; Mu, Yun; Ni, Yiming

    2017-01-01

    Abstract Background: Intermittent stuck valve after mechanical valve replacement surgery is a very rare and severe complication. Case summary: We present 1 case of a 53-year-old woman after aortic valve replacement for severe aortic valve stenosis combined with hypertrophy septum. She was diagnosed with intermittent stuck valve only 1 day after surgery by clinical symptoms, intraoperative transoesophageal echocardiogram, and intraoperative findings. Conclusions: Although indications for concomitant myectomy during aortic valve replacement are not clear, we recommend myectomy to prevent stuck valve after St Jude Medical Regent prosthesis replacement for severe aortic valve stenosis combined with hypertrophy septum. PMID:28248877

  13. Nontraumatic avulsion of aortic valve commissure as a cause of acute aortic valve regurgitation

    PubMed Central

    Chang, Rei-Yeuh; Chen, Chien-Chang; Hsu, Wei-Pang; Hsiao, Pei-Ching; Tsai, Han-Lin; Hsiao, Ping-Gune; Wu, Jiann-Der; Guo, How-Ran

    2016-01-01

    Abstract Background: Avulsion of the aortic valve commissure as a cause of acute aortic valve regurgitation is mostly due to trauma, infective endocarditis, or ascending aortic dissection. Nontraumatic avulsion of the aortic valve commissure is very rare. We reviewed the literature and analyzed potential risk factors of nontraumatic avulsion. Case presentation: An 80-year-old male with hypertension was seen in the emergency department with acute onset dyspnea. Echocardiogram revealed left ventricular hypertrophy with adequate systolic function, prolapse of the noncoronary cusp, and incomplete coaptation of the right coronary and noncoronary cusps with severe aortic valve regurgitation. Surgery revealed an avulsion between the left coronary and noncoronary cusps. Histopathology examination of the aortic valve showed myxoid degeneration, fibrosis, and calcification. Examination of the ascending aorta revealed myxoid degeneration and fragmentation of elastic fibers. Aortic valve replacement was performed, and the patient was alive and well 4 years after surgery. A review of the literature showed that more than three-fourths of the similar cases occurred in males, and about half in patients with hypertension and those 60 years of age or older. Conclusions: In the case of acute aortic regurgitation without a history of trauma, infection, or valvotomy, when 2 prolapsed aortic cusps are observed by echocardiography in the absence of an intimal tear of the ascending aorta, an avulsion of the aortic commissure should be suspected, especially in males with hypertension who are 60 years of age or older. PMID:27749570

  14. More than one way to control hair growth: regulatory mechanisms in enterobacteria that affect fimbriae assembled by the chaperone/usher pathway.

    PubMed

    Clegg, Steven; Wilson, Janet; Johnson, Jeremiah

    2011-05-01

    Many gram-negative enterobacteria produce surface-associated fimbriae that facilitate attachment and adherence to eucaryotic cells and tissues. These organelles are believed to play an important role during infection by enabling bacteria to colonize specific niches within their hosts. One class of these fimbriae is assembled using a periplasmic chaperone and membrane-associated scaffolding protein that has been referred to as an usher because of its function in fimbrial biogenesis. The presence of multiple types of fimbriae assembled by the chaperone/usher pathway can be found both within a single bacterial species and also among different genera. One way of controlling fimbrial assembly in these bacteria is at the genetic level by positively or negatively regulating fimbrial gene expression. This minireview considers the mechanisms that have been described to control fimbrial gene expression and uses specific examples to demonstrate both unique and shared properties of such regulatory mechanisms.

  15. Haemodynamics of giant cerebral aneurysm: A comparison between the rigid-wall, one-way and two-way FSI models

    NASA Astrophysics Data System (ADS)

    Khe, A. K.; Cherevko, A. A.; Chupakhin, A. P.; Bobkova, M. S.; Krivoshapkin, A. L.; Orlov, K. Yu

    2016-06-01

    In this paper a computer simulation of a blood flow in cerebral vessels with a giant saccular aneurysm at the bifurcation of the basilar artery is performed. The modelling is based on patient-specific clinical data (both flow domain geometry and boundary conditions for the inlets and outlets). The hydrodynamic and mechanical parameters are calculated in the frameworks of three models: rigid-wall assumption, one-way FSI approach, and full (two-way) hydroelastic model. A comparison of the numerical solutions shows that mutual fluid- solid interaction can result in qualitative changes in the structure of the fluid flow. Other characteristics of the flow (pressure, stress, strain and displacement) qualitatively agree with each other in different approaches. However, the quantitative comparison shows that accounting for the flow-vessel interaction, in general, decreases the absolute values of these parameters. Solving of the hydroelasticity problem gives a more detailed solution at a cost of highly increased computational time.

  16. The effects of three-dimensional defects on one-way surface plasmon propagation for photonic topological insulators comprised of continuum media

    PubMed Central

    Hassani Gangaraj, S. Ali; Nemilentsau, Andrei; Hanson, George W.

    2016-01-01

    We have investigated one-way surface plasmon-polaritons (SPPs) at the interface of a continuum magnetoplasma material and metal, in the presence of three-dimensional surface defects. Bulk electromagnetic modes of continuum materials have Chern numbers, analogous to those of photonic crystals. This can lead to the appearance of topologically-protected surface modes at material interfaces, propagating at frequencies inside the bandgap of the bulk materials. Previous studies considered two-dimensional structures; here we consider the effect of three-dimensional defects, and show that, although backward propagation/reflection cannot occur, side scattering does take place and has significant effect on the propagation of the surface mode. Several different waveguiding geometries are considered for reducing the effects of side-scattering, and we also consider the effects of metal loss. PMID:27444542

  17. Solar wind interaction with Mars Upper atmosphere: Results from the one-way coupling between the Multi-fluid MHD model and the M-TGCM model

    NASA Astrophysics Data System (ADS)

    Dong, C.; Bougher, S. W.; Ma, Y.; Toth, G.; Nagy, A. F.; Brain, D. A.; Najib, D.

    2012-12-01

    The study of the solar wind interaction with Mars upper atmosphere/ionosphere has triggered great interest in recent years. Among the large number of topics in this research area, the investigation of ion escape rates has become increasingly important due to its potential impact on the long-term evolution of Mars atmosphere (e.g., loss of water) over its history. In the present work, we adopt the 3D Mars neutral atmosphere profiles from the well-regarded Mars Thermospheric Global Circulation Model (M-TGCM) and one-way couple it with the 3D BATS-R-US Mars multi-fluid MHD model that solves separate momentum equations for each ion species. The M-TGCM model takes into account the effects of the solar cycle (solar minimum: F10.7=70 and solar maximum: F10.7=200 with equinox condition: Ls=0), allowing us to investigate the effects of the solar cycle on the Mars upper atmosphere ion escape by using a one-way coupling, i.e., the M-TGCM model outputs are used as inputs for the multi-fluid MHD model. A case for solar maximum with extremely high solar wind parameters is also investigated to estimate how high the escape flux can be for such an extreme case. Moreover, the ion escape flux along a satellite trajectory will be studied. This has the potential to provide predictions of ion escape rates for comparison to future data to be returned by the MAVEN mission (2012-2016). In order to make the code run more efficiently, we adopt a more appropriate grid structure compared to the one used previously. This new grid structure will benefit us to investigate the effects of some dynamic events (such as CME and dust storm) on the ion escape flux.

  18. Tailored One-Way and Two-Way Shape Memory Capabilities of Poly(ɛ-Caprolactone)-Based Systems for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Pandini, Stefano; Riccò, Theonis; Borboni, Alberto; Bodini, Ileana; Vetturi, David; Cambiaghi, Danilo; Toselli, Maurizio; Paderni, Katia; Messori, Massimo; Pilati, Francesco; Chiellini, Federica; Bartoli, Cristina

    2014-07-01

    This paper investigates the shape memory capabilities of semicrystalline networks, focusing the attention on poly(ɛ-caprolactone) (PCL) systems, a class of materials that allows to satisfy important requirements for their applications as biomedical devices, such as the good biocompatibility, the fast recovery of large "temporary" shape configurations, and the easy tailoring of the transformation temperatures. The materials were prepared with various crosslink densities and crosslinking methodologies; in particular, beside a thermal crosslinking based on reactive methacrylic end groups, a novel type of covalently crosslinked semicrystalline systems was prepared by a sol-gel approach from alkoxysilane-terminated PCL precursors, so as to avoid potentially toxic additives typically used for free-radical thermal curing. The materials were subjected to biological tests, to study their ability in sustaining cell adhesion and proliferation, and to thermal characterizations, to evaluate the possibility to tailor their melting and crystallization temperatures. The one-way shape memory (i.e., the possibility to set the material in a given configuration and to recover its pristine shape) and the two-way shape memory response (i.e., the triggered change between two distinguished shapes on the application of an on-off stimulus) were studied by applying optimized thermo-mechanical cyclic histories. The ability to fix the applied shape and to recover the original one on the application of heating (i.e., the one-way effect) was evaluated on tensile bars; further, to investigate a potential application as self-expandable stents, isothermal shape memory experiments were carried out also on tubular specimens, previously folded in a temporary compact configuration. The two-way response was studied through the application of a constant load and of a heating/cooling cycle from above melting to below the crystallization temperature, leading to a reversible elongation/contraction effect

  19. Adaptation of methodology to select structural alternatives of one-way slab in residential building to the guidelines of the European Committee for Standardization (CEN/TC 350)

    SciTech Connect

    Fraile-Garcia, Esteban; Ferreiro-Cabello, Javier; Martinez-Camara, Eduardo; Jimenez-Macias, Emilio

    2015-11-15

    The European Committee for Standardization (CEN) through its Technical Committee CEN/TC-350 is developing a series of standards for assessing the building sustainability, at both product and building levels. The practical application of the selection (decision making) of structural alternatives made by one-way slabs leads to an intermediate level between the product and the building. Thus the present study addresses this problem of decision making, following the CEN guidelines and incorporating relevant aspects of architectural design into residential construction. A life cycle assessment (LCA) is developed in order to obtain valid information for the decision making process (the LCA was developed applying CML methodology although Ecoindicator99 was used in order to facilitate the comparison of the values); this information (the carbon footprint values) is contrasted with other databases and with the information from the Environmental Product Declaration (EPD) of one of the lightening materials (expanded polystyrene), in order to validate the results. Solutions of different column disposition and geometries are evaluated in the three pillars of sustainable construction on residential construction: social, economic and environmental. The quantitative analysis of the variables used in this study enables and facilitates an objective comparison in the design stage by a responsible technician; the application of the proposed methodology reduces the possible solutions to be evaluated by the expert to 12.22% of the options in the case of low values of the column index and to 26.67% for the highest values. - Highlights: • Methodology for selection of structural alternatives in buildings with one-way slabs • Adapted to CEN guidelines (CEN/TC-350) for assessing the building sustainability • LCA is developed in order to obtain valid information for the decision making process. • Results validated comparing carbon footprint, databases and Env. Product Declarations

  20. Space Weather at Mars: 3-D studies using one-way coupling between the Multi-fluid MHD, M-GITM and M-AMPS models

    NASA Astrophysics Data System (ADS)

    Dong, Chuanfei

    This dissertation presents numerical simulation results of the solar wind interaction with the Martian upper atmosphere by using three comprehensive 3-D models: the Mars Global Ionosphere Thermosphere Model (M-GITM), the Mars exosphere Monte Carlo model Adaptive Mesh Particle Simulator (M-AMPS), and the BATS-R-US Mars multi-fluid MHD (MF-MHD) model. The coupled framework has the potential to provide improved predictions for ion escape rates for comparison with future data to be returned by the MAVEN mission (2014-2016) and thereby improve our understanding of present day escape processes. Estimates of ion escape rates over Mars history must start from properly validated models that can be extrapolated into the past. This thesis aims to build a model library for the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, which will thus enhance the science return from the MAVEN mission. In this thesis, we aim to address the following four main scientific questions by adopting the one-way coupled framework developed here: (1) What are the Martian ion escape rates at the current epoch and ancient times? (2) What controls the ion escape processes at the current epoch? How are the ion escape variations connected to the solar cycle, crustal field orientation and seasonal variations? (3) How do the variable 3-D cold neutral thermosphere and hot oxygen corona affect the solar wind-Mars interaction? (4) How does the Martian atmosphere respond to extreme variations (e.g., ICMEs) in the solar wind and its interplanetary environment? These questions are closely related to the primary scientific goals of NASA's MAVEN mission and European Space Agency's Mars Express (MEX) mission. We reasonably answer all these four questions at the end of this thesis by employing the one-way coupled framework and comparing the simulation results with both MEX and MAVEN observational data.

  1. Face-Sealing Butterfly Valve

    NASA Technical Reports Server (NTRS)

    Tervo, John N.

    1992-01-01

    Valve plate made to translate as well as rotate. Valve opened and closed by turning shaft and lever. Interactions among lever, spring, valve plate, and face seal cause plate to undergo combination of translation and rotation so valve plate clears seal during parts of opening and closing motions.

  2. Sliding-gate valve

    DOEpatents

    Usnick, George B.; Ward, Gene T.; Blair, Henry O.; Roberts, James W.; Warner, Terry N.

    1979-01-01

    This invention is a novel valve of the slidable-gate type. The valve is designed especially for long-term use with highly abrasive slurries. The sealing surfaces of the gate are shielded by the valve seats when the valve is fully open or closed, and the gate-to-seat clearance is swept with an inflowing purge gas while the gate is in transit. A preferred form of the valve includes an annular valve body containing an annular seat assembly defining a flow channel. The seat assembly comprises a first seat ring which is slidably and sealably mounted in the body, and a second seat ring which is tightly fitted in the body. These rings cooperatively define an annular gap which, together with passages in the valve body, forms a guideway extending normal to the channel. A plate-type gate is mounted for reciprocation in the guideway between positions where a portion of the plate closes the channel and where a circular aperture in the gate is in register with the channel. The valve casing includes opposed chambers which extend outwardly from the body along the axis of the guideway to accommodate the end portions of the gate. The chambers are sealed from atmosphere; when the gate is in transit, purge gas is admitted to the chambers and flows inwardly through the gate-to-seat-ring, clearance, minimizing buildup of process solids therein. A shaft reciprocated by an external actuator extends into one of the sealed chambers through a shaft seal and is coupled to an end of the gate. Means are provided for adjusting the clearance between the first seat ring and the gate while the valve is in service.

  3. Long life valve design concepts

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

    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.

  4. Quartz ball valve

    NASA Technical Reports Server (NTRS)

    Goetz, C.; Ingle, W. M. (Inventor)

    1980-01-01

    A ball valve particularly suited for use in the handling of highly corrosive fluids is described. It is characterized by a valve housing formed of communicating segments of quartz tubing, a pair of communicating sockets disposed in coaxial alignment with selected segments of tubing for establishing a pair of inlet ports communicating with a common outlet port, a ball formed of quartz material supported for displacement between the sockets and configured to be received alternately thereby, and a valve actuator including a rod attached to the ball for selectively displacing the ball relative to each of the sockets for controlling fluid flow through the inlet ports.

  5. Mesofluidic two stage digital valve

    DOEpatents

    Jansen, John F; Love, Lonnie J; Lind, Randall F; Richardson, Bradley S

    2013-12-31

    A mesofluidic scale digital valve system includes a first mesofluidic scale valve having a valve body including a bore, wherein the valve body is configured to cooperate with a solenoid disposed substantially adjacent to the valve body to translate a poppet carried within the bore. The mesofluidic scale digital valve system also includes a second mesofluidic scale valve disposed substantially perpendicular to the first mesofluidic scale valve. The mesofluidic scale digital valve system further includes a control element in communication with the solenoid, wherein the control element is configured to maintain the solenoid in an energized state for a fixed period of time to provide a desired flow rate through an orifice of the second mesofluidic valve.

  6. Fast valve based on double-layer eddy-current repulsion for disruption mitigation in Experimental Advanced Superconducting Tokamak.

    PubMed

    Zhuang, H D; Zhang, X D

    2015-05-01

    A fast valve based on the double-layer eddy-current repulsion mechanism has been developed on Experimental Advanced Superconducting Tokamak (EAST). In addition to a double-layer eddy-current coil, a preload system was added to improve the security of the valve, whereby the valve opens more quickly and the open-valve time becomes shorter, making it much safer than before. In this contribution, testing platforms, open-valve characteristics, and throughput of the fast valve are discussed. Tests revealed that by choosing appropriate parameters the valve opened within 0.15 ms, and open-valve times were no longer than 2 ms. By adjusting working parameter values, the maximum number of particles injected during this open-valve time was estimated at 7 × 10(22). The fast valve will become a useful tool to further explore disruption mitigation experiments on EAST in 2015.

  7. Mitral Valve Prolapse

    MedlinePlus

    ... Kawasaki Disease Long Q-T Syndrome Marfan Syndrome Metabolic Syndrome Mitral Valve Prolapse Myocardial Bridge Myocarditis Obstructive Sleep Apnea Pericarditis Peripheral Vascular Disease Rheumatic Fever Sick Sinus Syndrome Silent Ischemia Stroke Sudden ...

  8. Pulmonary valve stenosis

    MedlinePlus

    ... valvuloplasty - pulmonary Images Heart valves References Carabello BA. Valvular heart disease. In: Goldman L, Schafer AI, eds. Goldman's Cecil ... Saunders; 2016:chap 69. Otto CM, Bownow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ...

  9. Valve Repair or Replacement

    MedlinePlus

    ... invasive valve surgery can be done using a robot. Robotic surgery does not require a large incision ... the procedure. The Texas Heart Institute has a robot. With robotic surgery, the surgeon has a control ...

  10. Mitral Valve Prolapse.

    ERIC Educational Resources Information Center

    Bergy, Gordon G.

    1980-01-01

    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)

  11. Pulmonary Valve Stenosis

    MedlinePlus

    ... as mild, moderate or severe, depending on a measurement of the blood pressure difference between the right ... balloon, widening the narrowed valve to increase blood flow, and then removes the balloon. The most common ...

  12. Bidirectional piston valve

    DOEpatents

    Fischer, Harry C.

    1977-01-01

    This invention is a reversing valve having an inlet, an outlet, and an inlet-outlet port. The valve is designed to respond to the introduction of relatively high-pressure fluid at its inlet or, alternatively, of lower-pressure fluid at its inlet-outlet port. The valve includes an axially slidable assembly which is spring-biased to a position where it isolates the inlet and connects the inlet-outlet port to the outlet. The admission of high-pressure fluid to the inlet displaces the slidable assembly to a position where the outlet is isolated and the inlet is connected to the inlet-outlet port. The valve is designed to minimize pressure drops and leakage. It is of a reliable and comparatively simple design.

  13. Bicuspid aortic valve

    MedlinePlus

    ... stiff and not open up. This is called aortic stenosis , which causes the heart to pump harder than usual to get blood through the valve. The aorta may become enlarged with this condition. BAV is ...

  14. THERMALLY OPERATED VAPOR VALVE

    DOEpatents

    Dorward, J.G. Jr.

    1959-02-10

    A valve is presented for use in a calutron to supply and control the vapor to be ionized. The invention provides a means readily operable from the exterior of the vacuum tank of the apparatuss without mechanical transmission of forces for the quick and accurate control of the ionizing arc by a corresponding control of gas flow theretos thereby producing an effective way of carefully regulating the operation of the calutron. The invention consists essentially of a tube member extending into the charge bottle of a calutron devices having a poppet type valve closing the lower end of the tube. An electrical heating means is provided in the valve stem to thermally vary the length of the stem to regulate the valve opening to control the flow of material from the charge bottle.

  15. Transcatheter Pulmonary Valve Replacement by Hybrid Approach Using a Novel Polymeric Prosthetic Heart Valve: Proof of Concept in Sheep

    PubMed Central

    Xu, Tong-yi; Zhang, Zhi-gang; Li, Xin; Han, Lin; Xu, Zhi-yun

    2014-01-01

    Background Since 2000, transcatheter pulmonary valve replacement has steadily advanced. However, the available prosthetic valves are restricted to bioprosthesis which have defects like poor durability. Polymeric heart valve is thought as a promising alternative to bioprosthesis. In this study, we introduced a novel polymeric transcatheter pulmonary valve and evaluated its feasibility and safety in sheep by a hybrid approach. Methods We designed a novel polymeric trileaflet transcatheter pulmonary valve with a balloon-expandable stent, and the valve leaflets were made of 0.1-mm expanded polytetrafluoroethylene (ePTFE) coated with phosphorylcholine. We chose glutaraldehyde-treated bovine pericardium valves as control. Pulmonary valve stents were implanted in situ by a hybrid transapical approach in 10 healthy sheep (8 for polymeric valve and 2 for bovine pericardium valve), weighing an average of 22.5±2.0 kg. Angiography and cardiac catheter examination were performed after implantation to assess immediate valvular functionality. After 4-week follow-up, angiography, echocardiography, computed tomography, and cardiac catheter examination were used to assess early valvular function. One randomly selected sheep with polymeric valve was euthanized and the explanted valved stent was analyzed macroscopically and microscopically. Findings Implantation was successful in 9 sheep. Angiography at implantation showed all 9 prosthetic valves demonstrated orthotopic position and normal functionality. All 9 sheep survived at 4-week follow-up. Four-week follow-up revealed no evidence of valve stent dislocation or deformation and normal valvular and cardiac functionality. The cardiac catheter examination showed the peak-peak transvalvular pressure gradient of the polymeric valves was 11.9±5.0 mmHg, while that of two bovine pericardium valves were 11 and 17 mmHg. Gross morphology demonstrated good opening and closure characteristics. No thrombus or calcification was seen

  16. Liquid blocking check valve

    DOEpatents

    Merrill, John T.

    1984-01-01

    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.

  17. Valve for gas centrifuges

    DOEpatents

    Hahs, Charles A.; Burbage, Charles H.

    1984-01-01

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

  18. Bicuspid Aortic Valve

    DTIC Science & Technology

    2006-08-01

    severe aortic stenosis . Figure 1F. Oblique axial cine bright blood imaging through the valve plane of the aorta, demonstrates the aortic valve to...the ascending aorta. This moderate to large jet is consistent with moderate to severe aortic stenosis . No diastolic jet to suggest aortic ...conditions. Functional impairment of the aortic valve—namely aortic stenosis and aortic regurgitation—is the most common complication (in up to 68-85% of

  19. Piston and valve assembly

    SciTech Connect

    Rolder, G. K.

    1985-10-01

    A downhole hydraulically actuated pump assembly of either the free or fixed type lifts formation fluid from the bottom of a borehole to the surface of the ground. The downhole pump has a power piston which actuates a production plunger. A valve means is concentrically arranged within the power piston. A stationary, hollow valve control rod extends through the power piston and through the valve means, with a lower marginal end of the control rod terminating within the production plunger. Power fluid flows through the control rod and to the valve means. As the power piston reciprocates within the engine cylinder, means on the control rod actuates the valve means between two alternant positions so that power fluid is applied to the bottom face of the power piston to thereby cause the power piston to reciprocate upward; and thereafter, the control rod causes the valve means to shift to the other position, whereupon spent power fluid is exhausted from the engine cylinder. The spent power fluid is admixed with production fluid and is conducted to the surface of the ground.

  20. Engine valve train module

    SciTech Connect

    Wirth, R.C.; De Klep, E.L.

    1988-01-26

    In a reciprocating internal combustion engine of the type having an engine block means defining at least one cylinder with a first port and a second port in flow communication therewith, a first valve and a second valve reciprocably located to control flow through the first and second ports, respectively, and normally biased to a port closed position, the improvement is described comprising a valve train module that includes a housing adapted to be secured by machine screws to the engine block means above the first and second valves; an engine driven camshaft having axial spaced apart first and second cam lobes operatively supported for rotation in the housing; a lifter guide bore in the housing located substantially coaxial with the reciprocating axis of the first valve; a direct acting hydraulic lash adjuster operatively supported in the lifter guide bore with one end thereof engaging the first cam lobe and at its opposite end being operatively connected to the first valve. A follower guide bore is in the housing operatively aligned relative to the second cam lobe; a hollow rocker shaft is operatively fixed in the housing in parallel spaced apart relationship to the engine driven camshaft; a rocker arm pivotably supported intermediate its ends by the rocker shaft.

  1. Plans to improve the experimental limit in the comparison of the east-west and west-east one-way light propagation times on the rotating earth

    NASA Technical Reports Server (NTRS)

    Alley, C. O.; Kiess, T. E.; Nelson, R. A.; Sergienko, A. V.; Shih, Y. H.; Wang, B. C.; Yang, F. M.

    1993-01-01

    The preceding paper describes the results so far (interrupted in the Spring of 1989 because of lack of funds) of an experiment comparing the one-way light propagation times on the surface of the rotating Earth. For the 20 Km path length component in the East-West direction the predicted difference between the opposite sense propagation times would be 160 ps, if the approximately 360 Km/s surface speed of the Earth gives effective light speeds of 3 x 10(exp 8) m/s +/- 360 m/s. This could lead to a prediction of the difference between the clock transport and the light pulse synchronization methods described in the preceding paper: delta(T) = 0.5 (160) = 80 ps. The current upper bound of approximately 100 ps for delta(T) is limited by poorly understood systematic errors. The most important seems to be intensity-dependent time delays in the remote light pulse avalanche photo-diode detector. This will be replaced by a continuously operating circular scan streak camera having single photon sensitivity and a time resolution of approximately 5 ps. (This camera has recently been developed by the Xian Institute of Optics and Precision Mechanics in the P.R.C.). Better isolation from shocks and vibration for the Sigma-Tau hydrogen maser during transport will be provided. It is hoped that delta(T) is less than 20 ps can be achieved.

  2. Solar wind interaction with Mars upper atmosphere: Results from the one-way coupling between the multifluid MHD model and the MTGCM model

    NASA Astrophysics Data System (ADS)

    Dong, Chuanfei; Bougher, Stephen W.; Ma, Yingjuan; Toth, Gabor; Nagy, Andrew F.; Najib, Dalal

    2014-04-01

    The 3-D multifluid Block Adaptive Tree Solar-wind Roe Upwind Scheme (BATS-R-US) MHD code (MF-MHD) is coupled with the 3-D Mars Thermospheric general circulation model (MTGCM). The ion escape rate from the Martian upper atmosphere is investigated by using a one-way coupling approach, i.e., the MF-MHD model incorporates the effects of 3-D neutral atmosphere profiles from the MTGCM model. The calculations are carried out for two cases with different solar cycle conditions. The calculated total ion escape flux (the sum of three major ionospheric species, O+, O2+, and CO2+) for solar cycle maximum conditions (6.6×1024 s-1) is about 2.6 times larger than that of solar cycle minimum conditions (2.5×1024 s-1). Our simulation results show good agreement with recent observations of 2-3×1024 s-1 (O+, O2+, and CO2+) measured near solar cycle minimum conditions by Mars Express. An extremely high solar wind condition is also simulated which may mimic the condition of coronal mass ejections or corotating interaction regions passing Mars. Simulation results show that it can lead to a significant value of the escape flux as large as 4.3×1025s-1.

  3. Cooling the two-dimensional short spherocylinder liquid to the tetratic phase: Heterogeneous dynamics with one-way coupling between rotational and translational hopping.

    PubMed

    Su, Yen-Shuo; I, Lin

    2015-07-01

    We numerically demonstrate the transition from the isotropic liquid to the tetratic phase with quasilong-range tetratic alignment order (i.e., with nearly parallel or perpendicular aligned rods), for the cold two-dimensional (2D) short spherocylinder system before crystallization and investigate the thermal assisted heterogeneous rotational and translational micromotions. Comparing with the 2D liquid of isotropic particles, spherocylinders introduce extra rotational degrees of freedom and destroy packing isotropy and the equivalence between rotational and translational motions. It is found that cooling leads to the stronger dynamical heterogeneity with more cooperative hopping and the stronger retardations of rotational hopping than translational hopping. Under topological constraints from nearly parallel and perpendicular rods of the tetratic phase, longitudinal and transverse translational hopping can occur without rotational hopping, but not the reverse. The empty space trailing a neighboring translational hopping patch is needed for triggering the patch rotational hopping with its translational motion into the empty space. It is the origin for the observed increasing separation of hopping time scales and the one-way coupling between rotational and translational hopping. Strips of longitudinally or transversely aligned rods can be ruptured and reconnected with neighboring strips through buckling, kink formation, and patch rotation, under the unbalanced torques or forces from their neighboring rods and thermal kicks.

  4. One-Way Multishape-Memory Effect and Tunable Two-Way Shape Memory Effect of Ionomer Poly(ethylene-co-methacrylic acid).

    PubMed

    Lu, Lu; Li, Guoqiang

    2016-06-15

    Reversible elongation by cooling and contraction by heating, without the need for repeated programming, is well-known as the two-way shape-memory effect (2W-SME). This behavior is contrary to the common physics-contraction when cooling and expansion when heating. Materials with such behavior may find many applications in real life, such as self-sufficient grippers, fastening devices, optical gratings, soft actuators, and sealant. Here, it is shown that ionomer Surlyn 8940, a 50-year old polymer, exhibits both one-way multishape-memory effects and tunable two-way reversible actuation. The required external tensile stress to trigger the tunable 2W-SME is very low when randomly jumping the temperatures within the melting transition window. With a proper one-time programming, "true" 2W-SME (i.e., 2W-SME without the need for an external tensile load) is also achieved. A long training process is not needed to trigger the tunable 2W-SME. Instead, a proper one-time tensile programming is sufficient to trigger repeated and tunable 2W-SME. Because the 2W-SME of the ionomer Surlyn is driven by the thermally reversible network, here crystallization and melting transitions of the semicrystalline poly(ethylene-co-methacrylic acid), it is believed that a class of thermally reversible polymers should also exhibit tunable 2W-SMEs.

  5. Early postpartum mitral valve thrombosis requiring extra corporeal membrane oxygenation before successful valve replacement.

    PubMed

    Halldorsdottir, H; Nordström, J; Brattström, O; Sennström, M M; Sartipy, U; Mattsson, E

    2016-05-01

    Pregnancy is associated with an increased risk of thrombosis in women with mechanical prosthetic heart valves. We present the case of a 29-year-old woman who developed early postpartum mitral valve thrombus after an elective cesarean delivery. The patient had a mechanical mitral valve and was treated with warfarin in the second trimester, which was replaced with high-dose dalteparin during late pregnancy. Elective cesarean delivery was performed under general anesthesia at 37weeks of gestation. The patient was admitted to the intensive care unit for postoperative care and within 30min she developed dyspnea and hypoxia requiring mechanical ventilation. She deteriorated rapidly and developed pulmonary edema, worsening hypoxia and severe acidosis. Urgent extra corporeal membrane oxygenation was initiated. Transesophageal echocardiography revealed a mitral valve thrombus. The patient underwent a successful mitral valve replacement after three days on extra corporeal membrane oxygenation. This case highlights the importance of multidisciplinary care and frequent monitoring of anticoagulation during care of pregnant women with prosthetic heart valves.

  6. Mitral disc-valve variance

    PubMed Central

    Berroya, Renato B.; Escano, Fernando B.

    1972-01-01

    This report deals with a rare complication of disc-valve prosthesis in the mitral area. A significant disc poppet and struts destruction of mitral Beall valve prostheses occurred 20 and 17 months after implantation. The resulting valve incompetence in the first case contributed to the death of the patient. The durability of Teflon prosthetic valves appears to be in question and this type of valve probably will be unacceptable if there is an increasing number of disc-valve variance in the future. Images PMID:5017573

  7. 9. BUTTERFLY VALVE CONTROL DIABLO POWERHOUSE. BUTTERFLY VALVES WERE MANUFACTURED ...

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

    9. BUTTERFLY VALVE CONTROL DIABLO POWERHOUSE. BUTTERFLY VALVES WERE MANUFACTURED BY THE PELTON WATER WHEEL COMPANY IN 1931, 1989. - Skagit Power Development, Diablo Powerhouse, On Skagit River, 6.1 miles upstream from Newhalem, Newhalem, Whatcom County, WA

  8. Implantation of the CoreValve percutaneous aortic valve.

    PubMed

    Lamarche, Yoan; Cartier, Raymond; Denault, André Y; Basmadjian, Arsène; Berry, Colin; Laborde, Jean-Claude; Bonan, Raoul

    2007-01-01

    Surgical aortic valve replacement is the only recommended treatment for significant aortic valve stenosis. Percutaneous aortic valve replacement appears to be a novel option for high-risk patients. We report the implantation of the ReValving system (CoreValve, Paris, France) in a 64-year-old woman who was refused aortic valve replacement surgery for critical aortic stenosis and left ventricular dysfunction because of severe pulmonary fibrosis. After anesthesia, the patient was put on femorofemoral cardiopulmonary bypass, and underwent a balloon valvuloplasty with subsequent retrograde aortic valve replacement by the ReValving system. Transesophageal echocardiographic monitoring of the patient's hemodynamics showed immediate improvements of the valvular area and left ventricular ejection fraction and only traces of paravalvular leaks. The patient was easily weaned from ventilation and resumed activity soon after the surgery. A multidisciplinary approach is presently necessary to offer a reliable and safe procedure.

  9. Perceval Sutureless Valve – are Sutureless Valves Here?

    PubMed Central

    Chandola, Rahul; Teoh, Kevin; Elhenawy, Abdelsalam; Christakis, George

    2015-01-01

    With the advent of transcatheter aortic valve implantation (TAVI) techniques, a renewed interest has developed in sutureless aortic valve concepts in the last decade. The main feature of sutureless aortic valve implantation is the speed of insertion, thus making implantation easier for the surgeon. As a result, cross clamp times and myocardial ischemia may be reduced. The combined procedures (CABG with AVR in particular) can be done with a short cross clamp time. Perceval valve also provides an increased effective orifice area as compared with a stented bioprosthesis. Sutureless implantation of the Perceval valve is not only associated with shorter cross-clamp and cardiopulmonary bypass times but improved clinical outcomes too. This review covers the sutureless aortic valves and their evolution, with elaborate details on Perceval S valve in particular (which is the most widely used sutureless valve around the globe). PMID:25394851

  10. Computer aided detection of endobronchial valves

    NASA Astrophysics Data System (ADS)

    Ochs, Robert A.; Goldin, Jonathan G.; Abtin, Fereidoun; Ghurabi, Raffi; Rao, Ajay; Ahmad, Shama; da Costa, Irene; Brown, Matthew

    2008-03-01

    The ability to automatically detect and monitor implanted devices may serve an important role in patient care and the evaluation of device and treatment efficacy. The purpose of this research was to develop a system for the automated detection of one-way endobronchial valves implanted as part of a clinical trial for less invasive lung volume reduction. Volumetric thin section CT data was obtained for 275 subjects; 95 subjects implanted with 246 devices were used for system development and 180 subjects implanted with 354 devices were reserved for testing. The detection process consisted of pre-processing, pattern-recognition based detection, and a final device selection. Following the pre-processing, a set of classifiers were trained using AdaBoost to discriminate true devices from false positives (such as calcium deposits). The classifiers in the cascade used simple features (the mean or max attenuation) computed near control points relative to a template model of the valve. Visual confirmation of the system output served as the gold standard. FROC analysis was performed for the evaluation; the system could be set so the mean sensitivity was 96.5% with a mean of 0.18 false positives per subject. These generic device modeling and detection techniques may be applicable to other devices and useful for monitoring the placement and function of implanted devices.

  11. Multi-decadal scenario simulation over Korea using a one-way double-nested regional climate model system. Part 2: future climate projection (2021 2050)

    NASA Astrophysics Data System (ADS)

    Im, Eun-Soon; Ahn, Joong-Bae; Kwon, Won-Tae; Giorgi, Filippo

    2008-02-01

    An analysis of simulated future surface climate change over the southern half of Korean Peninsula using a RegCM3-based high-resolution one-way double-nested system is presented. Changes in mean climate as well as the frequency and intensity of extreme climate events are discussed for the 30-year-period of 2021 2050 with respect to the reference period of 1971 2000 based on the IPCC SRES B2 emission scenario. Warming in the range of 1 4°C is found throughout the analysis region and in all seasons. The warming is maximum in the higher latitudes of the South Korean Peninsula and in the cold season. A large reduction in snow depth is projected in response to the increase of winter minimum temperature induced by the greenhouse warming. The change in precipitation shows a distinct seasonal variation and a substantial regional variability. In particular, we find a large increase of wintertime precipitation over Korea, especially in the upslope side of major mountain systems. Summer precipitation increases over the northern part of South Korea and decreases over the southern regions, indicating regional diversity. The precipitation change also shows marked intraseasonal variations throughout the monsoon season. The temperature change shows a positive trend throughout 2021 2050 while the precipitation change is characterized by pronounced interdecadal variations. The PDF of the daily temperature is shifted towards higher values and is somewhat narrower in the scenario run than the reference one. The number of frost days decreases markedly and the number of hot days increases. The regional distribution of heavy precipitation (over 80 mm/day) changes considerably, indicating changes in flood vulnerable regions. The climate change signal shows pronounced fine scale signal over Korea, indicating the need of high-resolution climate simulations

  12. Echocardiographic features of aortic ball valve prosthesis malfunction.

    PubMed

    Weisburst, M R; Singh, A K; Riley, R S

    1982-11-01

    A case of aortic ball valve prosthesis malfunction is described in which the poppet became alternately stuck in the open and closed position. The patient experienced chest pain followed by pulmonary edema and cardiac arrest. Malfunction of prosthetic valve was diagnosed on echocardiogram and cardiopulmonary resuscitation was carried out until a Bjork-Shiley valve could be inserted in place of the faulty prosthesis. At the time of the operation, poppet migration had occurred and the poppet could not be found. Subsequent Bjork-Shiley aortic valve prosthesis dysfunction was suggested by variation in the intensity of the aortic opening sound and in the duration of the systolic ejection period. Fluoroscopy revealed the missing poppet in the left ventricle. Following surgical removal of the poppet, "normal" Bjork-Shiley valve function was restored.

  13. Fast closing valve

    SciTech Connect

    Hanson, C.L.

    1984-01-10

    A valve is provided for protecting the high vacuum of a particle accelerator in the event of air leakage, wherein the valve provides an axially symmetrical passage to avoid disturbance of the partical beam during normal operation, and yet enables very rapid and tight closure of the beam-carrying pipe in the event of air leakage. The valve includes a ball member which can rotate between a first position wherein a bore in the member is aligned with the beam pipe, and a second position out of line with the pipe. A seal member is flexibly sealed to the pipe, and has a seal end which can move tightly against the ball member after the bore has rotated out of line with the pipe, to thereby assure that the seal member does not retard rapid rotation of the ball valve member. The ball valve member can be rapidly rotated by a conductive arm fixed to it and which is rotated by the discharge of a capacitor bank through coils located adjacent to the arm.

  14. Fast closing valve

    DOEpatents

    Hanson, Clark L.

    1984-01-10

    A valve is provided for protecting the high vacuum of a particle accelera in the event of air leakage, wherein the valve provides an axially symmetrical passage to avoid disturbance of the partical beam during normal operation, and yet enables very rapid and tight closure of the beam-carrying pipe in the event of air leakage. The valve includes a ball member (30) which can rotate between a first position wherein a bore (32) in the member is aligned with the beam pipe, and a second position out of line with the pipe. A seal member (38) is flexibly sealed to the pipe, and has a seal end which can move tightly against the ball member after the bore has rotated out of line with the pipe, to thereby assure that the seal member does not retard rapid rotation of the ball valve member. The ball valve member can be rapidly rotated by a conductive arm (40) fixed to it and which is rotated by the discharge of a capacitor bank through coils (44, 45) located adjacent to the arm.

  15. Sutureless aortic valve replacement

    PubMed Central

    Phan, Kevin

    2015-01-01

    The increasing incidence of aortic stenosis and greater co-morbidities and risk profiles of the contemporary patient population has driven the development of minimally invasive aortic valve surgery and percutaneous transcatheter aortic valve implantation (TAVI) techniques to reduce surgical trauma. Recent technological developments have led to an alternative minimally invasive option which avoids the placement and tying of sutures, known as “sutureless” or rapid deployment aortic valves. Potential advantages for sutureless aortic prostheses include reducing cross-clamp and cardiopulmonary bypass (CPB) duration, facilitating minimally invasive surgery and complex cardiac interventions, whilst maintaining satisfactory hemodynamic outcomes and low paravalvular leak rates. However, given its recent developments, the majority of evidence regarding sutureless aortic valve replacement (SU-AVR) is limited to observational studies and there is a paucity of adequately-powered randomized studies. Recently, the International Valvular Surgery Study Group (IVSSG) has formulated to conduct the Sutureless Projects, set to be the largest international collaborative group to investigate this technology. This keynote lecture will overview the use, the potential advantages, the caveats, and current evidence of sutureless and rapid deployment aortic valve replacement (AVR). PMID:25870807

  16. Aortic valve replacement with the De Bakey valve.

    PubMed

    Paton, B C; Pine, M B

    1976-10-01

    De Bakey prostheses were inserted in 29 patients with aortic valve disease between October, 1970, and May, 1972. Ten patients have died, but all but one of the remaining 19 have beel followed for a minimum of 19 months. Evaluation of the results in these subjects indicates that the function of the De Bakey valve compares favorably with that of other aortic valve prostheses.

  17. 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

  18. 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

  19. Myxomatous Mitral Valve with Prolapse and Flail Scallop

    PubMed Central

    Fan, Jerry; Timbrook, Alexa; Said, Sarmad; Babar, Kamran; Teleb, Mohamed; Mukherjee, Debabrata; Abbas, Aamer

    2016-01-01

    Summary Background Myxomatous mitral valve with prolapse are classically seen with abnormal leaflet apposition during contraction of the heart. Hemodynamic disorders can result from eccentric mitral regurgitation usually caused by chordae tendinae rupture or papillary muscle dysfunction. Echocardiography is the gold standard for evaluation of leaflet flail and prolapse due to high sensitivity and specificity. Though most mitral valve prolapse are asymptomatic those that cause severe regurgitation need emergent surgical intervention to prevent disease progression. Case Report We report a 54 year old Hispanic male who presented with progressively worsening dyspnea and palpitations. Initial evaluation was significant for atrial fibrillation on electrocardiogram with subsequent echocardiography revealing myxomatous mitral valve with prolapse. Following surgical repair of the mitral valve, the dyspnea and palpitations resolved. Conclusions Mitral valve prolapse is a common valvular abnormality but the pathogenic cause of myxomatous valves has not been elucidated. Several theories describe multiple superfamilies of proteins to be involved in the process. Proper identification of these severe mitral regurgitation due to these disease valves will help relieve symptomatic mitral valve prolapse patients. PMID:27279924

  20. What Is Mitral Valve Prolapse?

    MedlinePlus

    ... may not close tightly. These flaps normally help seal or open the valve. Much of the time, ... and tricuspid valves close. They form a tight seal that prevents blood from flowing back into the ...

  1. Medications for Heart Valve Symptoms

    MedlinePlus

    ... Peripheral Artery Disease Venous Thromboembolism Aortic Aneurysm More Medications for Heart Valve Symptoms Updated:Sep 21,2016 How do medications help people with valve problems? People who are ...

  2. Locking apparatus for gate valves

    DOEpatents

    Fabyan, Joseph; Williams, Carl W.

    1988-01-01

    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.

  3. Locking apparatus for gate valves

    DOEpatents

    Fabyan, J.; Williams, C.W.

    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 further 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.

  4. Aortic valve surgery - minimally invasive

    MedlinePlus

    ... of the heart is reduced. This is called aortic stenosis. The aortic valve can be replaced using: Minimally ... RN, Wang A. Percutaneous heart valve replacement for aortic stenosis: state of the evidence. Ann Intern Med . 2010; ...

  5. Valve-spring Surge

    NASA Technical Reports Server (NTRS)

    Marti, Willy

    1937-01-01

    Test equipment is described that includes a system of three quartz indicators whereby three different pressures could be synchronized and simultaneously recorded on a single oscillogram. This equipment was used to test the reliction of waves at ends of valve spring, the dynamical stress of the valve spring for a single lift of the valve, and measurement of the curve of the cam tested. Other tests included simultaneous recording of the stress at both ends of the spring, spring oscillation during a single lift as a function of speed, computation of amplitude of oscillation for a single lift by harmonic analysis, effect of cam profile, the setting up of resonance, and forced spring oscillation with damping.

  6. Sliding valve pump

    SciTech Connect

    Rupert, C.L.

    1980-09-09

    A sliding valve pump for oil wells which includes a working barrel having a plurality of apertures located in spaced relationship in the wall thereof and a pair of travelling valves fitted within the working barrel and carried by a plunger rod, the valves also having a plurality of apertures or ports for periodic registration with the ports in the working barrel wall to facilitate pumping of fluid from an oil reservoir or pool to the surface. The pump is designed to pull the oil-gas mixture from the reservoir pool into the lower section of the working barrel on the downward stroke, and to subsequently pump the collected oil through the barrel and tubing upwardly toward the surface on the upward stroke.

  7. Variable Valve Actuation

    SciTech Connect

    Jeffrey Gutterman; A. J. Lasley

    2008-08-31

    Many approaches exist to enable advanced mode, low temperature combustion systems for diesel engines - such as premixed charge compression ignition (PCCI), Homogeneous Charge Compression Ignition (HCCI) or other HCCI-like combustion modes. The fuel properties and the quantity, distribution and temperature profile of air, fuel and residual fraction in the cylinder can have a marked effect on the heat release rate and combustion phasing. Figure 1 shows that a systems approach is required for HCCI-like combustion. While the exact requirements remain unclear (and will vary depending on fuel, engine size and application), some form of substantially variable valve actuation is a likely element in such a system. Variable valve actuation, for both intake and exhaust valve events, is a potent tool for controlling the parameters that are critical to HCCI-like combustion and expanding its operational range. Additionally, VVA can be used to optimize the combustion process as well as exhaust temperatures and impact the after treatment system requirements and its associated cost. Delphi Corporation has major manufacturing and product development and applied R&D expertise in the valve train area. Historical R&D experience includes the development of fully variable electro-hydraulic valve train on research engines as well as several generations of mechanical VVA for gasoline systems. This experience has enabled us to evaluate various implementations and determine the strengths and weaknesses of each. While a fully variable electro-hydraulic valve train system might be the 'ideal' solution technically for maximum flexibility in the timing and control of the valve events, its complexity, associated costs, and high power consumption make its implementation on low cost high volume applications unlikely. Conversely, a simple mechanical system might be a low cost solution but not deliver the flexibility required for HCCI operation. After modeling more than 200 variations of the

  8. Hydrogen gas relief valve

    DOEpatents

    Whittlesey, Curtis C.

    1985-01-01

    An improved battery stack design for an electrochemical system having at least one cell from which a gas is generated and an electrolyte in communication with the cell is described. The improved battery stack design features means for defining a substantially closed compartment for containing the battery cells and at least a portion of the electrolyte for the system, and means in association with the compartment means for selectively venting gas from the interior of the compartment means in response to the level of the electrolyte within the compartment means. The venting means includes a relief valve having a float member which is actuated in response to the level of the electrolyte within the compartment means. This float member is adapted to close the relief valve when the level of the electrolyte is above a predetermined level and open the relief valve when the level of electrolyte is below this predetermined level.

  9. Magnetostrictive valve assembly

    NASA Technical Reports Server (NTRS)

    Richard, James A. (Inventor)

    2008-01-01

    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.

  10. Self-regulating valve

    DOEpatents

    Humphreys, D.A.

    1982-07-20

    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.

  11. Ball valve safety screen

    SciTech Connect

    Bolding, B.H.

    1981-09-01

    A device for preventing unwanted objects from entering the ball assembly of a float collar or float shoe and otherwise damaging or plugging the valve mechanism therein is disclosed. The device comprises a screen constructed of expanded metal and rigidly affixed to the interior of the float collar or float shoe above the ball valve assembly. The screen portion is either mounted to the interior surface of the float collar sleeve by an annular structural member or mounted to a structural band which is partially embedded in the concrete portion of the float collar or casing guide shoe.

  12. Lightweight Valve Closes Duct Quickly

    NASA Technical Reports Server (NTRS)

    Fournier, Walter L.; Burgy, N. Frank

    1991-01-01

    Expanding balloon serves as lightweight emergency valve to close wide duct. Uninflated balloon stored in housing of duct. Pad resting on burst diaphragm protects balloon from hot gases in duct. Once control system triggers valve, balloon inflates rapidly to block duct. Weighs much less than does conventional butterfly, hot-gas, or poppet valve capable of closing duct of equal diameter.

  13. Lipomatous hamartoma of mitral valve.

    PubMed

    Bhat, Seetharama P S; Gowda, Girish S L; Chikkatur, Raghavendra; Nanjappa, Manjunath C

    2016-01-01

    Primary cardiac tumors are very rare, and tumors arising from cardiac valves are extremely rare. We present a case of lipomatous hamartoma of the mitral valve in a young female. This is the 6th case of lipomatous hamartoma of the mitral valve to be reported. We discuss the operative and histopathological findings.

  14. Valve stem and packing assembly

    DOEpatents

    Wordin, John J.

    1991-01-01

    A valve stem and packing assembly is provided in which a rotatable valve stem includes a first tractrix surface for sliding contact with a stem packing and also includes a second tractrix surface for sliding contact with a bonnet. Force is applied by means of a spring, gland flange, and gland on the stem packing so the stem packing seals to the valve stem and bonnet. This configuration serves to create and maintain a reliable seal between the stem packing and the valve stem. The bonnet includes a second complementary tractrix surface for contacting the second sliding tractrix surface, the combination serving as a journal bearing for the entire valve stem and packing assembly. The journal bearing so configured is known as a Schiele's pivot. The Schiele's pivot also serves to maintain proper alignment of the valve stem with respect to the bonnet. Vertical wear between the surfaces of the Schiele's pivot is uniform at all points of contact between the second sliding tractrix surface and the second complementary tractrix surface of a bonnet. The valve stem is connected to a valve plug by means of a slip joint. The valve is opened and closed by rotating the valve stem. The slip joint compensates for wear on the Schiele's pivot and on the valve plug. A ledge is provided on the valve bonnet for the retaining nut to bear against. The ledge prevents overtightening of the retaining nut and the resulting excessive friction between stem and stem packing.

  15. Valve stem and packing assembly

    DOEpatents

    Wordin, J.J.

    1991-09-03

    A valve stem and packing assembly is provided in which a rotatable valve stem includes a first tractrix surface for sliding contact with a stem packing and also includes a second tractrix surface for sliding contact with a bonnet. Force is applied by means of a spring, gland flange, and gland on the stem packing so the stem packing seals to the valve stem and bonnet. This configuration serves to create and maintain a reliable seal between the stem packing and the valve stem. The bonnet includes a second complementary tractrix surface for contacting the second sliding tractrix surface, the combination serving as a journal bearing for the entire valve stem and packing assembly. The journal bearing so configured is known as a Schiele's pivot. The Schiele's pivot also serves to maintain proper alignment of the valve stem with respect to the bonnet. Vertical wear between the surfaces of the Schiele's pivot is uniform at all points of contact between the second sliding tractrix surface and the second complementary tractrix surface of a bonnet. The valve stem is connected to a valve plug by means of a slip joint. The valve is opened and closed by rotating the valve stem. The slip joint compensates for wear on the Schiele's pivot and on the valve plug. A ledge is provided on the valve bonnet for the retaining nut to bear against. The ledge prevents over tightening of the retaining nut and the resulting excessive friction between stem and stem packing. 2 figures.

  16. Prosthetic valve endocarditis: clinical findings and management.

    PubMed

    Horstkotte, D; Körfer, R; Loogen, F; Rosin, H; Bircks, W

    1984-10-01

    Prosthetic valve endocarditis (PVE) was shown in 46 patients out of a group of 2163 carrying prosthetic heart valves. The cumulative rate of early PVE was 1.4% and 1.5% for PVE occurring between the 60th day and 10 years after surgery. In 37% of all cases this was caused by staphylococci, 20% by streptococci, and 13% Gram negative species. Fungi were found in 9% and mixed infections in 21%. The incidence of staphylococci, Gram negative pathogens and fungi was significantly higher in early PVE. In 5 patients, valve involvement consisted in echocardiographically shown vegetations and/or obstructive thromboendocarditis. In 90% of 37 patients who developed paravalvular leakages, there was high intravascular haemolysis uncharacteristic of the type of prosthesis implanted. In 70% fluoroscopy revealed disproportionate tilting of the prosthetic annulus, and in 75% there was a distinct echocardiographic pattern in the closing movement of the valve poppet. The cumulative survival rate after six months was 31% for the conservatively treated, and 66% for the medically plus surgically treated patients. Survival rates at the end of a maximum follow-up of 20 years was 15% with conservative treatment and 51% after primary surgical therapy. The prognosis was worse (P less than 0.01) in patients who, during aortic PVE, developed heart failure refractant to therapy due to haemodynamically significant prosthetic valve dysfunction, to sepsis that persisted for more than 72 h despite antibiotic therapy, to major septic embolism or to acute renal failure. The retrospective prognosis was more favourable for patients with early aortic (P less than 0.02) or mitral (P less than 0.05) valve re-replacement than for patients who had been treated medically only.

  17. Transcatheter Valve-in-Valve: A Cautionary Tale.

    PubMed

    Luc, Jessica G Y; Shanks, Miriam; Tyrrell, Benjamin D; Welsh, Robert C; Butler, Craig R; Meyer, Steven R

    2016-09-01

    Transcatheter aortic valve replacement (TAVR) by valve-in-valve (VIV) implantation is an alternative treatment for high-risk patients with a degenerating aortic bioprosthesis. We present a case of transapical TAVR VIV with a 29-mm Edwards SAPIEN XT (ESV) (Edwards Lifesciences, Irvine, CA) into a 29-mm Medtronic Freestyle stentless bioprosthesis (Medtronic Inc, Minneapolis, MN) in which unanticipated dilatation of the Freestyle bioprosthesis resulted in intraprocedural embolization of the TAVR valve, necessitating urgent conversion to a conventional surgical aortic valve replacement (AVR). Our experience suggests that TAVR VIV with the 29-mm ESV in the setting of a degenerated 29-mm Freestyle stentless bioprosthesis must be undertaken with caution.

  18. Early-onset Streptomyces endocarditis in a prosthetic aortic valve.

    PubMed

    Shehatha, Jaffar S; Taha, Abdulsalam Y

    2017-02-01

    A 66-year-old Australian man underwent elective replacement of a severely stenotic aortic valve with a 22-mm Medtronic-Hall valve. Six weeks later, he was readmitted with worsening dyspnea, fever, and mild anemia. Investigations confirmed pulmonary edema and moderate periprosthetic aortic regurgitation. The pulmonary edema was managed conservatively, and a second 22-mm Medtronic-Hall valve was implanted. Infective endocarditis was suspected in the aortic annulus below the orifice of the right coronary artery. A bacteriological study revealed a rare bacteria of Streptomyces species. The patient received intensive antibiotic therapy over a 6-week period of hospitalization, and the aortic regurgitation disappeared one week postoperatively.

  19. Evaluation of a high response electrohydraulic digital control valve

    NASA Technical Reports Server (NTRS)

    Anderson, R. L.

    1973-01-01

    The application is described of a digital control valve on an electrohydraulic servo actuator. The digital control problem is discussed in general as well as the design and evaluation of a breadboard actuator. The evaluation revealed a number of problems associated with matching the valve to a hydraulic load. The problems were related to lost motion resulting from bulk modulus and leakage. These problems were effectively minimized in the breadboard actuator by maintaining a 1000 psi back pressure on the valve circuit and thereby improving the effective bulk modulus.

  20. Improved Merge Valve

    NASA Technical Reports Server (NTRS)

    George-Falvy, Dez

    1992-01-01

    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.

  1. Aortic valve surgery - open

    MedlinePlus

    ... Saunders; 2012:chap 61. Otton CM, Bowow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ... Editorial team. Related MedlinePlus Health Topics Heart Surgery Heart Valve Diseases Browse the Encyclopedia A.D.A.M., Inc. ...

  2. Valve for cryogenic service

    DOEpatents

    Worwetz, H.A.

    1975-09-02

    This patent relates to a valve for use with a liquefied gas at cryogenic temperatures in which a pair of joined knife edges are bellows controlled to contact an indium alloy seat in an annular slot when flow is to be stopped. The sealing alloy may be renewed by heating in situ. (auth)

  3. Poppet valve tester

    NASA Technical Reports Server (NTRS)

    Tellier, G. F.

    1973-01-01

    Tester investigates fundamental factors affecting cyclic life and sealing performance of valve seats and poppets. Tester provides for varying impact loading of poppet against seat and rate of cycling, and controls amount and type of relative motion between sealing faces of seat and poppet. Relative motion between seat and poppet can be varied in three modes.

  4. Thermostatic Radiator Valve Evaluation

    SciTech Connect

    Dentz, Jordan; Ansanelli, Eric

    2015-01-01

    A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market.

  5. Valve for gas centrifuges

    DOEpatents

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

    1982-03-17

    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.

  6. Transcatheter aortic valve replacement

    MedlinePlus

    ... fully will restrict blood flow. This is called aortic stenosis. If there is also a leak, it is ... TAVR is used for people with severe aortic stenosis who aren't ... valve . In adults, aortic stenosis usually occurs due to calcium ...

  7. TUBE SHEARING VALVE

    DOEpatents

    Wilner, L.B.

    1960-05-24

    Explosive operated valves can be used to join two or more containers in fluid flow relationship, one such container being a sealed reservoir. The valve is most simply disposed by mounting it on the reservoir so thst a tube extends from the interior of the reservoir through the valve body, terminating at the bottom of the bore in a closed end; other containers may be similarly connected or may be open connected, as desired. The piston of the valve has a cutting edge at its lower end which shears off the closed tube ends and a recess above the cutting edge to provide a flow channel. Intermixing of the fluid being transferred with the explosion gases is prevented by a copper ring at the top of the piston which is force fitted into the bore at the beginning of the stroke. Although designed to avoid backing up of the piston at pressures up to 10,000 psi in the transferred fluid, proper operation is independent of piston position, once the tube ends were sheared.

  8. Posttraumatic tricuspid valve injury and severe tricuspid valve regurgitation.

    PubMed

    Gucuk Ipek, Esra

    2013-09-01

    A 66-year-old male was brought to our hospital following a car accident. He had subarachnoid hemorrhage, multiple rib fractures, and left hemopneumothorax. He was referred to the Cardiology Department for elevated troponin levels (42 ng/ml, reference 0-1 ng/ml). The electrocardiogram was free of ischemia, whereas the transthoracic echocardiography revealed dilated right heart chambers, enlarged tricuspid annulus and coaptation failure of the tricuspid valvular leaflets. There was rupture on the subvalvular apparatus of the anterior leaflet of the tricuspid valve with accompanying prolapse, causing severe tricuspid valvular regurgitation. The patient did not present right ventricular failure signs and symptoms; he was referred to surgery after the resolution of associated thoracic and cranial injuries.

  9. Miniature Latching Valve

    NASA Technical Reports Server (NTRS)

    Johnson, A. David; Benson, Glendon M.

    2008-01-01

    A miniature latching valve has been invented to satisfy a need for an electrically controllable on/off pneumatic valve that is lightweight and compact and remains in the most recently commanded open or closed state when power is not supplied. The valve includes a poppet that is moved into or out of contact with a seat to effect closure or opening, respectively, of the flow path. Motion of the poppet is initiated by electrical heating of one of two opposing pairs of nickel/titanium shape-memory alloy (SMA) wires above their transition temperature: heated wires contract to their remembered length, applying tension to pull the poppet toward or away from the seat. A latch consisting mainly of a bistable Belleville washer (a conical spring) made of a hardened stainless steel operates between two stable positions corresponding to the fully closed or fully open state, holding the poppet in one of these positions when power is not applied to either pair of SMA wires. To obtain maximum actuation force and displacement, the SMA wires must be kept in tension. The mounting fixtures at the ends of the wires must support large tensile stresses without creating stress concentrations that would limit the fatigue lives of the wires. An earlier design provided for each wire to be crimped in a conical opening with a conical steel ferrule that was swaged into the opening to produce a large, uniformly distributed holding force. In a subsequent design, the conical ferrule was replaced with a larger crimped cylindrical ferrule depicted in the figure. A major problem in designing the valve was to protect the SMA wires from a bake-out temperature of 300 C. The problem was solved by incorporating the SMA wires into an actuator module that is inserted into a barrel of the valve body and is held in place by miniature clip rings.

  10. Multi-port valve assembly

    DOEpatents

    Guggenheim, S. Frederic

    1986-01-01

    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.

  11. Valve assembly for internal combustion engine

    SciTech Connect

    Wakeman, R.J.; Shea, S.F.

    1989-09-05

    This patent describes an improvement in a valve assembly for an internal combustion engine of the type including a valve having a valve stem, a valve guideway for mounting this valve for reciprocal strokes between opened and seated position, and spring means for biasing the valve into the seated position. The improvement comprising a valve spool of greater cross-sectional diameter as compared to the valve stem, and a valve spool guideway within which the valve spool is movable during the strokes of the valve, an upper surface of the valve spool and a portion of the spool guideway collectively establishing a damper chamber which varies in volume during the valve strokes. a feed passage for introducing oil into the damper chamber, and a bleed passage for discharging oil from the damper chamber. The bleed passages each laterally opening into the valve spool guideway.

  12. Cusp tear in bicuspid aortic valve possibly caused by phentermine.

    PubMed

    Yosefy, Chaim; Berman, Michael; Beeri, Ronen

    2006-01-13

    A 28 year old woman underwent echocardiography following an incidental finding of a diastolic murmur. She has been taking phentermine for weight reduction for 8 months. Trans-esophageal echocardiography revealed a tear of the posterior cusp of the aortic valve causing severe regurgitation. Phentermine is known to cause valvular disease with prolonged use, but aortic valve rupture was not previously reported as a complication of phentermine valvulopathy.

  13. Micro-valve pump light valve display

    DOEpatents

    Lee, Yee-Chun

    1993-01-01

    A flat panel display incorporates a plurality of micro-pump light valves (MLV's) to form pixels for recreating an image. Each MLV consists of a dielectric drop sandwiched between substrates, at least one of which is transparent, a holding electrode for maintaining the drop outside a viewing area, and a switching electrode from accelerating the drop from a location within the holding electrode to a location within the viewing area. The sustrates may further define non-wetting surface areas to create potential energy barriers to assist in controlling movement of the drop. The forces acting on the drop are quadratic in nature to provide a nonlinear response for increased image contrast. A crossed electrode structure can be used to activate the pixels whereby a large flat panel display is formed without active driver components at each pixel.

  14. Micro-valve pump light valve display

    DOEpatents

    Yeechun Lee.

    1993-01-19

    A flat panel display incorporates a plurality of micro-pump light valves (MLV's) to form pixels for recreating an image. Each MLV consists of a dielectric drop sandwiched between substrates, at least one of which is transparent, a holding electrode for maintaining the drop outside a viewing area, and a switching electrode from accelerating the drop from a location within the holding electrode to a location within the viewing area. The sustrates may further define non-wetting surface areas to create potential energy barriers to assist in controlling movement of the drop. The forces acting on the drop are quadratic in nature to provide a nonlinear response for increased image contrast. A crossed electrode structure can be used to activate the pixels whereby a large flat panel display is formed without active driver components at each pixel.

  15. Effect of nasal speaking valve on speech intelligibility under velopharyngeal incompetence: a questionnaire survey.

    PubMed

    Mikamo, S; Kodama, N; Pan, Q; Maeda, N; Minagi, S

    2015-02-01

    Velopharyngeal incompetence is known as a contributing factor to speech disorders. Suwaki et al. reported that nasal speaking valve (NSV) could improve dysarthria by regulating nasal emission utilising one-way valve. However, disease or condition which would be susceptible to treatment by NSV has not been clarified yet. This study aimed to evaluate the effect of NSV by questionnaire survey using ready-made NSV. Subjects were recruited through the internet bulletin, and NSV survey set was sent to the applicant. Sixty-six participants, who agreed to participate in this study, used NSV and mailed back the questionnaire which included self-evaluation and third-party evaluation of speech intelligibility. Statistical analysis revealed that the use of NSV resulted in significant speech intelligibility improvement in both self-evaluation and third-party evaluation (P < 0·01). Regarding the type of underlying disease of dysarthria, significant effect of NSV on self-evaluation of speech intelligibility could be observed in cerebrovascular disease and neurodegenerative disease (P < 0·01) and that on third-party evaluation in neurodegenerative disease (P < 0·01). Eighty-six percent of subjects showed improvement of speech intelligibility by shutting up nostrils by fingers, and the significant effect of NSV on both self-evaluation and third-party evaluation of speech intelligibility was observed (P < 0·001). From the results of this study, it was suggested that NSV would be effective in cerebrovascular disease and neurodegenerative disease, as well as in subjects whose speech intelligibility was improved by closing nostrils.

  16. Aspiration of a speaking valve

    PubMed Central

    Schembri, John; Cortis, Kelvin; Mallia Azzopardi, Charles; Montefort, Stephen

    2013-01-01

    Foreign body aspiration (FBA) is a relatively common and serious condition that can result in a spectrum of presentations ranging from incidental to acutely life-threatening. Described here is a case of aspiration of a tracheo-oesophageal speaking valve through a permanent tracheostomy that went unnoticed for a number of years, and an overview of the technique used for its removal. A 70-year-old ex-heavy smoker with a permanent tracheo-oesophageal fistula presented with a relatively recent history of increasing shortness of breath, sputum purulence and haemoptysis. Further investigation with a CT scan and bronchoscopy revealed the presence of a foreign body within his right lower lobe bronchus which was later removed by advancing a flexible bronchoscope over a rigid one. PMID:23861275

  17. Interlayer quality dependent graphene spin valve

    NASA Astrophysics Data System (ADS)

    Iqbal, Muhammad Zahir; Hussain, Ghulam; Siddique, Salma; Iqbal, Muhammad Waqas; Murtaza, Ghulam; Ramay, Shahid Mahmood

    2017-01-01

    It is possible to utilize the new class of materials for emerging two-dimensional (2D) spintronic applications. Here, the role of defects in the graphene interlayer and its influence on the spin valve signal is reported. The emergence of D peak in Raman spectrum reveals defects in the graphene layer. The linear I-V curve for defective and non-defective graphene samples indicate the ohmic nature of NiFe and graphene contact. A non-uniform magnetoresistive effect with a bump is persistently observed for defective graphene device at various temperatures, while a smooth and symmetric signal is detected for non-defective graphene spin valve. Parallel and antiparallel alignments of magnetization of magnetic materials shows low and high resistance states, respectively. The magnetoresistance (MR) ratio for defective graphene NiFe/graphene/NiFe spin valve is measured to be 0.16% at 300 K which progresses to 0.39% for non-defective graphene device at the same temperature. Similarly at 4.2 K the MR ratios are reported to be 0.41% and 0.78% for defective and non-defective graphene devices, respectively. Our investigation provides an evidence for relatively better response of the spin valve signal with high quality graphene interlayer.

  18. Fast acting multiple element valve

    DOEpatents

    Yang, Jefferson Y. S.; Wada, James M.

    1991-01-01

    A plurality of slide valve elements having plural axial-spaced annular parts and an internal slide are inserted into a bulkhead in a fluid conduit from a downstream side of the bulkhead, locked in place by a bayonet coupling and set screw, and project through the bulkhead into the upstream conduit. Pneumatic lines connecting the slide valve element actuator to pilot valves are brought out the throat of the valve element to the downstream side. Pilot valves are radially spaced around the exterior of the valve to permit the pneumatic lines to be made identical, thereby to minimize adverse timing tolerances in operation due to pressure variations. Ring manifolds surround the valve adjacent respective pilot valve arrangements to further reduce adverse timing tolerances due to pressure variations, the manifolds being directly connected to the respective pilot valves. Position sensors are provided the valve element slides to signal the precise time at which a slide reaches or passes through a particular point in its stroke to initiate a calibrated timing function.

  19. Fast-acting valve and uses thereof

    DOEpatents

    Meyer, J.A.

    1980-05-16

    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.

  20. Fast-acting valve and uses thereof

    DOEpatents

    Meyer, James A.

    1982-01-01

    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.

  1. Rotary multiposition valve

    DOEpatents

    Barclay, John A.; Dyson, Jack E.

    1985-01-01

    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.

  2. Stemless ball valve

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    A stemless ball valve comprising two flanges and a ball with a channel, two axis pins and two travel pins. One end of each axis and travel pin is fixedly attached to the ball, and the other end of each axis pin is lodged into a notch in the first or second flange such that the axis pin is allowed to rotate in the notch. The guide sleeve comprises two channels, and one end of each travel pin is situated within one of the two channels in the guide sleeve. An outer magnetic cartridge causes the inner magnetic cartridge and guide sleeve to rotate, and when the guide sleeve rotates, the travel pins move up and down within the channels in the guide sleeve. The movement of the travel pins within the channels in the guide sleeve causes the ball to rotate, thereby opening and closing the ball valve.

  3. Rotary multiposition valve

    DOEpatents

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

    1984-04-06

    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.

  4. Bioprosthetic mitral valve dysfunction due to native valve preserving procedure.

    PubMed

    Matsuno, Yukihiro; Mori, Yoshio; Umeda, Yukio; Takiya, Hiroshi

    2016-03-01

    Mitral valve replacement with preservation of the mitral leaflets and subvalvular apparatus is considered to maintain left ventricular geometry and function and reduce the risk of myocardial rupture. However, the routine use of this technique may lead to early complications such as left ventricular outflow tract obstruction and even mitral inflow obstruction, requiring reoperation. We describe a rare case of bioprosthetic mitral valve dysfunction caused by a native valve preserving procedure.

  5. Performance Characteristics of an Isothermal Freeze Valve

    SciTech Connect

    Hailey, A.E.

    2001-08-22

    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.

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

    NASA Technical Reports Server (NTRS)

    Drapeau, D. F. (Inventor)

    1984-01-01

    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.

  7. Coronary Ostial Stenosis after Aortic Valve Replacement

    PubMed Central

    Ziakas, Antonios G.; Economou, Fotios I.; Charokopos, Nicholas A.; Pitsis, Antonios A.; Parharidou, Despina G.; Papadopoulos, Thomas I.; Parharidis, Georgios E.

    2010-01-01

    Coronary ostial stenosis is a rare but potentially serious sequela after aortic valve replacement. It occurs in the left main or right coronary artery after 1% to 5% of aortic valve replacement procedures. The clinical symptoms are usually severe and may appear from 1 to 6 months postoperatively. Although the typical treatment is coronary artery bypass grafting, patients have been successfully treated by means of percutaneous coronary intervention. Herein, we present the cases of 2 patients in whom coronary ostial stenosis developed after aortic valve replacement. In the 1st case, a 72-year-old man underwent aortic valve replacement and bypass grafting of the saphenous vein to the left anterior descending coronary artery. Six months later, he experienced a non-ST-segment-elevation myocardial infarction. Coronary angiography revealed a critical stenosis of the right coronary artery ostium. In the 2nd case, a 78-year-old woman underwent aortic valve replacement and grafting of the saphenous vein to an occluded right coronary artery. Four months later, she experienced unstable angina. Coronary angiography showed a critical left main coronary artery ostial stenosis and occlusion of the right coronary artery venous graft. In each patient, we performed percutaneous coronary intervention and deployed a drug-eluting stent. Both patients were asymptomatic on 6-to 12-month follow-up. We attribute the coronary ostial stenosis to the selective ostial administration of cardioplegic solution during surgery. We conclude that retrograde administration of cardioplegic solution through the coronary sinus may reduce the incidence of postoperative coronary ostial stenosis, and that stenting may be an efficient treatment option. PMID:20844624

  8. Primitive Tumour of the Pulmonary Valve: Discussion of the Differential Diagnosis

    PubMed Central

    Ndjekembo-Shango, D.; Vallot, F.; Simonet, O.; De Kock, M.

    2017-01-01

    There is a paucity of information concerning cardiac tumours of the pulmonary valve due to their rarity at this location. We report a case of a 47-year-old patient suffering from haemoptysis, asthenia, and acute kidney injury (AKI). A transthoracic echocardiography (TTE) revealed a mass on the pulmonary valve. Further diagnostic investigation was completed until he exhibited worsening hemodynamic instability. This case emphasizes the lack of information regarding the management of a pulmonary valve tumour. PMID:28299209

  9. Treatment of mechanical aortic valve thrombosis with heparin and eptifibatide.

    PubMed

    Vora, Amit N; Gehrig, Thomas; Bashore, Thomas M; Kiefer, Todd L

    2014-07-01

    A 75-year old woman with a history of coronary disease status post 3-vessel coronary artery bypass grafting (CABG) 8 years ago and a repeat one-vessel CABG 2 years ago in the setting of aortic valve replacement with a #19 mm St. Jude bileaflet mechanical valve for severe aortic stenosis presented with two to three weeks of progressive dyspnea and increasing substernal chest discomfort. Echocardiography revealed a gradient to 31 mmHg across her aortic valve, increased from a baseline of 13 mmHg five months previously. Fluoroscopy revealed thrombosis of her mechanical aortic valve. She was not a candidate for surgery given her multiple comorbidities, and fibrinolysis was contraindicated given a recent subdural hematoma 1 year prior to presentation. She was treated with heparin and eptifibatide and subsequently demonstrated resolution of her aortic valve thrombosis. We report the first described successful use of eptifibatide in addition to unfractionated heparin for the management of subacute valve thrombosis in a patient at high risk for repeat surgery or fibrinolysis.

  10. Sequenced drive for rotary valves

    DOEpatents

    Mittell, Larry C.

    1981-01-01

    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.

  11. Semi-active compressor valve

    DOEpatents

    Brun, Klaus; Gernentz, Ryan S.

    2010-07-27

    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.

  12. Streamline coal slurry letdown valve

    DOEpatents

    Platt, Robert J.; Shadbolt, Edward A.

    1983-01-01

    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.

  13. Streamline coal slurry letdown valve

    DOEpatents

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

    1983-11-08

    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.

  14. Double-disc gate valve

    DOEpatents

    Wheatley, Seth J.

    1979-01-01

    This invention relates to an improvement in a conventional double-disc gate valve having a vertically movable gate assembly including a wedge, spreaders slidably engaged therewtih, a valve disc carried by the spreaders. When the gate assembly is lowered to a selected point in the valve casing, the valve discs are moved transversely outward to close inlet and outlet ports in the casing. The valve includes hold-down means for guiding the disc-and-spreader assemblies as they are moved transversely outward and inward. If such valves are operated at relatively high differential pressures, they sometimes jam during opening. Such jamming has been a problem for many years in gate valves used in gaseous diffusion plants for the separtion of uranium isotopes. The invention is based on the finding that the above-mentioned jamming results when the outlet disc tilts about its horizontal axis in a certain way during opening of the valve. In accordance with the invention, tilting of the outlet disc is maintained at a tolerable value by providing the disc with a rigid downwardly extending member and by providing the casing with a stop for limiting inward arcuate movement of the member to a preselected value during opening of the valve.

  15. Innovative Stemless Valve Eliminates Emissions

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Big Horn Valve Inc. (BHVI), of Sheridan, Wyoming, won a series of SBIR and Small Business Technology Transfer (STTR) contracts with Kennedy Space Center and Marshall Space Flight Center to explore and develop a revolutionary valve technology. BHVI developed a low-mass, high-efficiency, leak-proof cryogenic valve using composites and exotic metals, and had no stem-actuator, few moving parts, with an overall cylindrical shape. The valve has been installed at a methane coal gas field, and future applications are expected to include in-flight refueling of military aircraft, high-volume gas delivery systems, petroleum refining, and in the nuclear industry.

  16. Potential flow in engine valves

    NASA Technical Reports Server (NTRS)

    Eck, Bruno

    1925-01-01

    The extensive applicability of the hydrodynamic theory to the problems of engine construction is clearly shown in the following attempt to determine by exact methods the nature of the flow in valves under variously restricted conditions. Observation shows that two principal kinds of flow occur in simple flat-seated valves. For small valve lifts, the flow is along the horizontal wall and is therefore deflected 90 degrees, but for greater valve lifts the flow separates and forms a free stream, whose angle of deflection naturally increases with increasing lift. Both these kinds of flow can, in fact, be theoretically explained

  17. Latest design of gate valves

    SciTech Connect

    Kurzhofer, U.; Stolte, J.; Weyand, M.

    1996-12-01

    Babcock Sempell, one of the most important valve manufacturers in Europe, has delivered valves for the nuclear power industry since the beginning of the peaceful application of nuclear power in the 1960s. The latest innovation by Babcock Sempell is a gate valve that meets all recent technical requirements of the nuclear power technology. At the moment in the United States, Germany, Sweden, and many other countries, motor-operated gate and globe valves are judged very critically. Besides the absolute control of the so-called {open_quotes}trip failure,{close_quotes} the integrity of all valve parts submitted to operational forces must be maintained. In case of failure of the limit and torque switches, all valve designs have been tested with respect to the quality of guidance of the gate. The guidances (i.e., guides) shall avoid a tilting of the gate during the closing procedure. The gate valve newly designed by Babcock Sempell fulfills all these characteristic criteria. In addition, the valve has cobalt-free seat hardfacing, the suitability of which has been proven by friction tests as well as full-scale blowdown tests at the GAP of Siemens in Karlstein, West Germany. Babcock Sempell was to deliver more than 30 gate valves of this type for 5 Swedish nuclear power stations by autumn 1995. In the presentation, the author will report on the testing performed, qualifications, and sizing criteria which led to the new technical design.

  18. Fluid mechanics of heart valves.

    PubMed

    Yoganathan, Ajit P; He, Zhaoming; Casey Jones, S

    2004-01-01

    Valvular heart disease is a life-threatening disease that afflicts millions of people worldwide and leads to approximately 250,000 valve repairs and/or replacements each year. Malfunction of a native valve impairs its efficient fluid mechanic/hemodynamic performance. Artificial heart valves have been used since 1960 to replace diseased native valves and have saved millions of lives. Unfortunately, despite four decades of use, these devices are less than ideal and lead to many complications. Many of these complications/problems are directly related to the fluid mechanics associated with the various mechanical and bioprosthetic valve designs. This review focuses on the state-of-the-art experimental and computational fluid mechanics of native and prosthetic heart valves in current clinical use. The fluid dynamic performance characteristics of caged-ball, tilting-disc, bileaflet mechanical valves and porcine and pericardial stented and nonstented bioprostheic valves are reviewed. Other issues related to heart valve performance, such as biomaterials, solid mechanics, tissue mechanics, and durability, are not addressed in this review.

  19. Determinants of valve gating in collecting lymphatic vessels from rat mesentery

    PubMed Central

    Rahbar, Elaheh; Gashev, Anatoliy A.; Zawieja, David C.; Moore, James E.

    2011-01-01

    Secondary lymphatic valves are essential for minimizing backflow of lymph and are presumed to gate passively according to the instantaneous trans-valve pressure gradient. We hypothesized that valve gating is also modulated by vessel distention, which could alter leaflet stiffness and coaptation. To test this hypothesis, we devised protocols to measure the small pressure gradients required to open or close lymphatic valves and determine if the gradients varied as a function of vessel diameter. Lymphatic vessels were isolated from rat mesentery, cannulated, and pressurized using a servo-control system. Detection of valve leaflet position simultaneously with diameter and intraluminal pressure changes in two-valve segments revealed the detailed temporal relationships between these parameters during the lymphatic contraction cycle. The timing of valve movements was similar to that of cardiac valves, but only when lymphatic vessel afterload was elevated. The pressure gradients required to open or close a valve were determined in one-valve segments during slow, ramp-wise pressure elevation, either from the input or output side of the valve. Tests were conducted over a wide range of baseline pressures (and thus diameters) in passive vessels as well as in vessels with two levels of imposed tone. Surprisingly, the pressure gradient required for valve closure varied >20-fold (0.1–2.2 cmH2O) as a passive vessel progressively distended. Similarly, the pressure gradient required for valve opening varied sixfold with vessel distention. Finally, our functional evidence supports the concept that lymphatic muscle tone exerts an indirect effect on valve gating. PMID:21460194

  20. Determinants of valve gating in collecting lymphatic vessels from rat mesentery.

    PubMed

    Davis, Michael J; Rahbar, Elaheh; Gashev, Anatoliy A; Zawieja, David C; Moore, James E

    2011-07-01

    Secondary lymphatic valves are essential for minimizing backflow of lymph and are presumed to gate passively according to the instantaneous trans-valve pressure gradient. We hypothesized that valve gating is also modulated by vessel distention, which could alter leaflet stiffness and coaptation. To test this hypothesis, we devised protocols to measure the small pressure gradients required to open or close lymphatic valves and determine if the gradients varied as a function of vessel diameter. Lymphatic vessels were isolated from rat mesentery, cannulated, and pressurized using a servo-control system. Detection of valve leaflet position simultaneously with diameter and intraluminal pressure changes in two-valve segments revealed the detailed temporal relationships between these parameters during the lymphatic contraction cycle. The timing of valve movements was similar to that of cardiac valves, but only when lymphatic vessel afterload was elevated. The pressure gradients required to open or close a valve were determined in one-valve segments during slow, ramp-wise pressure elevation, either from the input or output side of the valve. Tests were conducted over a wide range of baseline pressures (and thus diameters) in passive vessels as well as in vessels with two levels of imposed tone. Surprisingly, the pressure gradient required for valve closure varied >20-fold (0.1-2.2 cmH(2)O) as a passive vessel progressively distended. Similarly, the pressure gradient required for valve opening varied sixfold with vessel distention. Finally, our functional evidence supports the concept that lymphatic muscle tone exerts an indirect effect on valve gating.

  1. Incorporating measured valve properties into a numerical model of a lymphatic vessel

    PubMed Central

    Macaskill, C.; Moore, J.E.

    2015-01-01

    An existing lumped-parameter model of multiple lymphangions (lymphatic vascular segments) in series is adapted for the incorporation of recent physiological measurements of lymphatic vascular properties. The new data show very marked nonlinearity of the passive pressure-diameter relation during distension, relative to comparable blood vessels, and complex valve behaviour. Since lymph is transported as a result of either the active contraction or the passive squeezing of vascular segments situated between two one-way valves, the performance of these valves is of primary importance. The valves display hysteresis (the opening and closing pressure-drop thresholds differ), a bias to staying open (both state changes occur when the trans-valve pressure drop is adverse), and pressure-drop threshold dependence on transmural pressure. These properties, in combination with the strong nonlinearity that valve operation represents, have in turn caused intriguing numerical problems in the model, and we describe numerical stratagems by which we have overcome the problems. The principal problem is also generalised into a relatively simple mathematical example, for which solution detail is provided using two different solvers. PMID:23387996

  2. All metal valve structure for gas systems

    DOEpatents

    Baker, Ray W.; Pawlak, Donald A.; Ramey, Alford J.

    1984-11-13

    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.

  3. Heart Valve Surgery Recovery and Follow Up

    MedlinePlus

    ... Venous Thromboembolism Aortic Aneurysm More Heart Valve Surgery Recovery and Follow Up Updated:Sep 14,2016 What to expect after heart valve surgery The normal recovery time after a heart valve surgery is usually ...

  4. 49 CFR 195.116 - Valves.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) Each valve must be both hydrostatically shell tested and hydrostatically seat tested without leakage to... the position of the valve (open, closed, etc.). (f) Each valve must be marked on the body or...

  5. Tomographic PIV behind a prosthetic heart valve

    NASA Astrophysics Data System (ADS)

    Hasler, D.; Landolt, A.; Obrist, D.

    2016-05-01

    The instantaneous three-dimensional velocity field past a bioprosthetic heart valve was measured using tomographic particle image velocimetry. Two digital cameras were used together with a mirror setup to record PIV images from four different angles. Measurements were conducted in a transparent silicone phantom with a simplified geometry of the aortic root. The refraction indices of the silicone phantom and the working fluid were matched to minimize optical distortion from the flow field to the cameras. The silicone phantom of the aorta was integrated in a flow loop driven by a piston pump. Measurements were conducted for steady and pulsatile flow conditions. Results of the instantaneous, ensemble and phase-averaged flow field are presented. The three-dimensional velocity field reveals a flow topology, which can be related to features of the aortic valve prosthesis.

  6. 241-AN-B valve pit manifold valves and position indication acceptance test procedure

    SciTech Connect

    VANDYKE, D.W.

    1999-08-25

    This document describes the method used to test design criteria for gear actuated ball valves installed in 241-AN-B Valve Pit located at 200E Tank Farms. The purpose of this procedure is to demonstrate the following: Equipment is properly installed, labeled, and documented on As-Built drawings; New Manifold Valves in the 241-AN-B Valve Pit are fully operable using the handwheel of the valve operators; New valve position indicators on the valve operators will show correct valve positions; New valve position switches will function properly; and New valve locking devices function properly.

  7. 241-AN-A valve pit manifold valves and position indication acceptance test procedure

    SciTech Connect

    VANDYKE, D.W.

    1999-08-25

    This document describes the method used to test design criteria for gear actuated ball valves installed in 241-AN-A Valve Pit located at 200E Tank Farms. The purpose of this procedure is to demonstrate the following: Equipment is properly installed, labeled, and documented on As-Built drawings; New Manifold Valves in the 241-AN-A Valve Pit are fully operable using the handwheel of the valve operators; New valve position indicators on the valve operators will show correct valve positions; New valve position switches will function properly; and New valve locking devices function properly.

  8. Rotary selector valve

    SciTech Connect

    Jones, J.A.; Herndon, J.W.

    1991-02-05

    This paper discusses a multi-port valve which internally supports a rotatable trunnion having an elbow passage between a nozzle portion of the trunnion and a lower end outlet that communicates with a test port of the valve body. The outer end of the nozzle has an axially reciprocable hollow seal piston with a seal support ring whose outer face is formed with an endless groove to receive an O-ring. An actuating shaft is coaxially mounted in an upper end of the trunnion and has a lower end with an eccentric pin engaged in a slot of the seal piston to reciprocate the seal piston into and out of sealing registration around a port selected by rotation of the trunnion. External ends of the actuating shaft and trunnion are respectively drivably coupled to a coaxial sprocket wheel and geneva wheel. A housing on top of the valve contains an input rotor fitted with a cam and a drive roller for engaging radial slots of the geneva wheel alternately with cam engagement of the dwell notches of the geneva wheel. Concurrently and in advance of forward rotation of the geneva wheel, a rotor driven seal actuating yoke a free end engages one of a series of radial slots of the sprocket to rotate the sprocket in a retrograde direction to disengage the seal. When the yoke is disengaged, a detent mechanism temporarily locks the geneva and sprocket wheels together for co-rotation in a forward direction as the geneva drive roller again comes into engagement with the geneva wheel. After the nozzle has been advanced one step, further rotation of the input rotor advances an arm independently pivotally mounted on the yoke to compress a spring mechanism to bias the yoke and sprocket to compress the seal on a seat around the next port.

  9. Overhead-valve engine

    SciTech Connect

    Tamba, S.; Miyake, H.; Fukui, N.

    1987-05-05

    An overhead valve engine is described comprising: push rod receiving bores, at least one of the push rod receiving bores being maintained in communication at one end with a crank chamber and at an opposite end with a rocker arm chamber and at least one other push rod receiving bore being maintained in communication with the rocker arm chamber; push rods contained within push rod receiving bores; and a breather chamber in communication with at least one other push rod receiving bore in the vicinity of a camshaft.

  10. Mitral valve surgery - minimally invasive

    MedlinePlus

    ... Saunders; 2012:chap 61. Otto CM, Bonow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ... Editorial team. Related MedlinePlus Health Topics Heart Surgery Heart Valve Diseases Mitral Valve Prolapse Browse the Encyclopedia A.D. ...

  11. Valve-"Health"-Monitoring System

    NASA Technical Reports Server (NTRS)

    Jensen, Scott L.; Drouant, George J.

    2009-01-01

    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.

  12. Valve designed with elastic seat

    NASA Technical Reports Server (NTRS)

    Mac Glashan, W. F., Jr.

    1965-01-01

    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.

  13. Variable gas leak rate valve

    DOEpatents

    Eernisse, Errol P.; Peterson, Gary D.

    1976-01-01

    A variable gas leak rate valve which utilizes a poled piezoelectric element to control opening and closing of the valve. The gas flow may be around a cylindrical rod with a tubular piezoelectric member encircling the rod for seating thereagainst to block passage of gas and for reopening thereof upon application of suitable electrical fields.

  14. Air flow through poppet valves

    NASA Technical Reports Server (NTRS)

    Lewis, G W; Nutting, E M

    1920-01-01

    Report discusses the comparative continuous flow characteristics of single and double poppet valves. The experimental data presented affords a direct comparison of valves, single and in pairs of different sizes, tested in a cylinder designed in accordance with current practice in aviation engines.

  15. Surge-damping vacuum valve

    DOEpatents

    Bullock, Jack C.; Kelly, Benjamin E.

    1980-01-01

    A valve having a mechanism for damping out flow surges in a vacuum system which utilizes a slotted spring-loaded disk positioned adjacent the valve's vacuum port. Under flow surge conditions, the differential pressure forces the disk into sealing engagement with the vacuum port, thereby restricting the flow path to the slots in the disk damping out the flow surge.

  16. FLUID PURIFIER AND SEALING VALVE

    DOEpatents

    Swanton, W.F.

    1962-04-24

    An improved cold trap designed to condense vapors and collect foreign particles in a flowing fluid is described. In the arrangement, a valve is provided to prevent flow reversal in case of pump failure and to act as a sealing valve. Provision is made for reducing the temperature of the fluid being processed, including a pre-cooling stage. (AEC)

  17. Antiphospholipid Syndrome and Libman-Sacks Endocarditis in a Bioprosthetic Mitral Valve.

    PubMed

    Sladek, Eric H; Accola, Kevin D

    2016-02-01

    This report describes one the first cases of antiphospholipid syndrome and Libman-Sacks endocarditis in a bioprosthetic valve. A redo mitral valve replacement was carried out owing to early deterioration of the prior valve. Initially it was considered secondary to rheumatic heart disease; however, pathology analysis and autoimmune workup revealed antiphospholipid syndrome with Libman-Sacks endocarditis. We believe certain populations with mitral valve stenosis may have an underlying antiphospholipid syndrome. As a result, there needs to be a lower threshold for identifying this disease.

  18. Heimlich valve for chest drainage.

    PubMed

    Heimlich, H J

    1983-01-01

    The Heimlich chest drainage valve was developed so that the process of draining the pleural cavity could be accomplished in a safe, relatively simple, and efficient manner. Replacing the cumbersome underwater drainage bottle system, the Heimlich valve connects to chest tubing and allows fluid and air to pass in one direction only. The valve, which functions in any position, need never be clamped, and regulated suction can be attached to it if necessary. The valve drains into a plastic bag that can be held at any level, allowing the patient undergoing chest drainage to be ambulatory simply by carrying the bag. The construction and function of the valve is easily understood by medical and nursing staffs. It is presterilized, stored in a sterile package, and readily utilized on emergency vehicles and in the operating room.

  19. Electro-Mechanical Coaxial Valve

    NASA Technical Reports Server (NTRS)

    Patterson, Paul R (Inventor)

    2004-01-01

    Coaxial valves usually contain only one moving part. It has not been easy, then, to provide for electric motor actuation. Many actuators being proposed involve designs which lead to bulky packages. The key facing those improving coaxial valves is the provision of suitable linear actuation. The valve herein indudes a valve housing with a flow channel there-through. Arranged in the flow channel is a closing body. In alignment with the closing body is a ball screw actuator which includes a ball nut and a cylindrical screw. The ball nut sounds a threaded portion of the cylindrical screw. The cylindrical screw is provided with a passageway there-through through which fluid flows. The cylindrical screw is disposed in the flow channel to become a control tube adapted to move toward and away from the valve seat. To rotate the ball nut an actuating drive is employed driven by a stepper motor.

  20. Titanium aluminide automotive engine valves

    SciTech Connect

    Hartfield-Wuensch, S.E.; Sperling, A.A.; Morrison, R.S.; Dowling, W.E. Jr.; Allison, J.E.

    1995-12-31

    The low density and high elevated temperature strength make titanium aluminide alloys an excellent candidate for automotive exhaust valve applications. Lighter weight valve train components allow either improved performance or reduction of valve spring loads which reduce noise and friction, thereby improving fuel economy. The key to successful application of TiAl alloys for automotive engine valves is not optimization of strength and ductility, but rather the development of a low-cost, high-volume manufacturing method. Different manufacturing approaches will be discussed in this paper, along with their advantages and disadvantages. Currently, casting appears to be the lowest-cost alternative that produces adequate material properties and emphasis is being placed on this manufacturing approach. The results of several successful engine tests will also be discussed, including results on a binary TiAl alloy. However, these engine tests have indicated that TiAl alloy valves will require tip protection and stem coating.

  1. A Parylene MEMS Electrothermal Valve

    PubMed Central

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

    2011-01-01

    The first microelectromechanical-system normally closed electrothermal valve constructed using Parylene C is described, which enables both low power (in milliwatts) and rapid operation (in milliseconds). This low-power valve is well suited for applications in wirelessly controlled implantable drug-delivery systems. The simple design was analyzed using both theory and modeling and then characterized in benchtop experiments. Operation in air (constant current) and water (current ramping) was demonstrated. Valve-opening powers of 22 mW in air and 33 mW in water were obtained. Following integration of the valve with catheters, our valve was applied in a wirelessly operated microbolus infusion pump, and the in vivo functionality for the appropriateness of use of this pump for future brain mapping applications in small animals was demonstrated. PMID:21350679

  2. Atmospheric dump valve engineering analysis

    SciTech Connect

    Mendoza, B.; McNemar, P.

    1990-01-01

    This report documents the activities undertaken after the atmospheric dump valves (ADVs) failed to operate following a Unit 3 reactor trip. The activities consisted of testing valves in all three units, examining Palo Verde Nuclear Generating Station (PVNGS) history with the valves, determining causes for failures, and making recommendations. The PVNGS engineering departments performed an in-depth review of the history, operation, maintenance, and design of ADVs. A preliminary mathematical model of the valves' dynamic behavior was developed by Arizona State University. The corrective actions are designed to eliminate the anomalies noted with the Unit 1 and 3 ADVs. Subsequent monitoring and testing activities following the planned modifications will ensure the ADVs remain operable during modes required by the PVNGS technical specifications. Through this increased monitoring and testing program, the valve modifications will be evaluated to confirm that the required level of reliability has been reached for the ADVs. The specific failures have been evaluated and the causes determined.

  3. Allograft Heart Valves: Current Aspects and Future Applications.

    PubMed

    Lisy, Milan; Kalender, Guenay; Schenke-Layland, Katja; Brockbank, Kelvin G M; Biermann, Anna; Stock, Ulrich Alfred

    2017-02-02

    Human heart valve allografts continue to represent almost perfect substitutes for heart valves. They have optimal hemodynamic characteristics and are highly resistant to infections. The first clinical use of allograft heart valves was as homovitals being transplanted after antibiotic incubation without any preservation. Since 1968, relatively standardized frozen cryopreservation (SFC) has been employed, including storage in vapor-phase liquid nitrogen. Disadvantages, particularly in pediatric patients, are limited availability due to organ scarcity, inability to grow, degeneration, immune response, and long-term failure. However, in contrast to alternative prosthetic or bioprosthetic heart valve replacements, they represent the best pediatric and juvenile replacement options for the pulmonary valve. Application of multiphoton imaging analysis for three-dimensional visualization of elastin and collagen by induction of autofluorescence without chemical fixation, embedding, and staining has revealed partial destruction of elastic and collagenous matrix in SFC valves. As the overall amount of collagen and elastin remains unchanged, the observed destruction is attributed to freezing-induced extracellular matrix damages due to ice crystal formation during SFC. The objective of this review is an assessment of current allograft preservation methods and the potential of novel preservation techniques to avoid ice formation with accompanied better long-term function.

  4. Dynamic Spin Valve

    NASA Astrophysics Data System (ADS)

    Demirtas, Sezen; Koymen, Ali; Salamon, Myron

    2010-03-01

    In this study we investigate a dynamic extension of well known classic spin valves. Ultra thin films were dc sputtered in a UHV chamber and their dynamic responses were measured by ferromagnetic resonance (FMR). Two Co layers, separated by a nonmagnetic Ag layer--thick enough to suppress exchange coupling--were deposited, with one of them coupled to a Gd underlayer, forming a Co(1)/Ag/Co(2)/Gd multilayer. At room temperature both Co(1) and Co(2) FMR's are observed for the external magnetic field in the plane of the film. The field for resonance of Co(2) is reduced significantly relative to Co(1), with the paramagnetic moment of the Gd apparently added to the Co magnetization, and the linewidth is broader. Spin pumping effects are minimal since Co(1) and Co(2) do not resonate at the same field.. The Co(2) FMR disappears at the TC of Gd leaving the linewidth of the Co(1) FMR weakly temperature dependent down to the compensation temperature of the Co(2)/Gd bilayer. Below that point, the two Co layers in this dynamic spin valve device are in antiparallel alignment, leading to strong broadening of the Co(1) FMR with decreasing temperature.

  5. Recirculating valve lash adjuster

    SciTech Connect

    Stoody, R.R.

    1987-02-24

    This patent describes an internal combustion engine with a valve assembly of the type including overhead valves supported by a cylinder head for opening and closing movements in a substantially vertical direction and a rotatable overhead camshaft thereabove lubricated by engine oil pumped by an engine oil pump. A hydraulic lash adjuster with an internal reservoir therein is solely supplied with run-off lubricating oil from the camshaft which oil is pumped into the internal reservoir of the lash adjuster by self-pumping operation of the lash adjuster produced by lateral forces thereon by the rotative operation of the camshaft comprising: a housing of the lash adjuster including an axially extending bore therethrough with a lower wall means of the housing closing the lower end thereof; a first plunger member being closely slidably received in the bore of the housing and having wall means defining a fluid filled power chamber with the lower wall means of the housing; and a second plunger member of the lash adjuster having a portion being loosely slidably received and extending into the bore of the housing for reciprocation therein. Another portion extends upwardly from the housing to operatively receive alternating side-to-side force inputs from operation of the camshaft.

  6. Differences in Aortic Valve and Left Ventricular Parameters Related to the Severity of Myocardial Fibrosis in Patients with Severe Aortic Valve Stenosis

    PubMed Central

    Song, Inyoung; Ko, Sung Min; Yi, Jeong Geun; Chee, Hyun Keun; Kim, Jun Seok

    2017-01-01

    Objective This study investigated the morphological and functional characteristics of the aortic valve and the left ventricular (LV) systolic functional parameters and myocardial mass related to the severity of myocardial fibrosis (MF) in patients with severe aortic valve stenosis (AS). Materials and Methods We retrospectively enrolled 81 patients (48 men; mean age: 59±12 years) with severe AS who underwent transthoracic echocardiography (TTE), cardiac computed tomography (CCT), and cardiovascular magnetic resonance (CMR) within 1 month and subsequent aortic valve surgery. Degree of MF was determined on delayed contrast-enhanced CMR with visual sub-segmental analysis-based quantification and was classified into three groups (no, mild, and severe) for identifying the differences in LV function and characteristics of the aortic valve. One-way ANOVA, Chi-square test or Fisher’s exact test were used to compare variables of the three groups. Univariate multinomial logistic regression analysis was performed to determine the association between the severity of MF and variables on imaging modalities. Results Of 81 patients, 34 (42%) had MF (mild, n = 18; severe, n = 16). Aortic valve calcium volume score on CCT, aortic valve area, LV mass index, LV end-diastolic volume index on CMR, presence of mild aortic regurgitation (AR), transaortic mean pressure gradient, and peak velocity on TTE were significantly different among the three groups and were associated with severity of MF on a univariate multinomial logistic regression analysis. Aortic valve calcium grade was different (p = 0.008) among the three groups but not associated with severity of MF (p = 0.375). Conclusions A multi-imaging approach shows that severe AS with MF is significantly associated with more severe calcific AS, higher LV end-diastolic volume, higher LV mass, and higher prevalence of mild AR. PMID:28129367

  7. Diagnosis and treatment of early bioprosthetic malfunction in the mitral valve position due to thrombus formation.

    PubMed

    Butnaru, Adi; Shaheen, Joseph; Tzivoni, Dan; Tauber, Rachel; Bitran, Daniel; Silberman, Shuli

    2013-11-01

    Bioprosthetic valve thrombosis is uncommon and the diagnosis is often elusive and may be confused with valve degeneration. We report our experience with mitral bioprosthetic valve thrombosis and suggest a therapeutic approach. From 2002 to 2011, 149 consecutive patients who underwent mitral valve replacement with a bioprosthesis at a single center were retrospectively screened for clinical or echocardiographic evidence of valve malfunction. Nine were found to have valve thrombus. All 9 patients had their native valve preserved, representing 24% of those with preserved native valves. Five patients (group 1) presented with symptoms of congestive heart failure at 16.4 ± 12.4 months after surgery. Echocardiogram revealed homogenous echo-dense film on the ventricular surface of the bioprosthesis with elevated transvalvular gradient, resembling early degeneration. The first 2 patients underwent reoperation: valve thrombus was found and confirmed by histologic examination. Based on these, the subsequent 3 patients received anticoagulation treatment with complete thrombus resolution: mean mitral gradient decreased from 23 ± 4 to 6 ± 1 mm Hg and tricuspid regurgitation gradient decreased from 83 ± 20 to 49 ± 5 mm Hg. Four patients (group 2) were asymptomatic, but routine echocardiogram showed a discrete mass on the ventricular aspect of the valve: 1 underwent reoperation to replace the valve and 3 received anticoagulation with complete resolution of the echocardiographic findings. In conclusion, bioprosthetic mitral thrombosis occurs in about 6% of cases. In our experience, onset is early, before anticipated valve degeneration. Clinical awareness followed by an initial trial with anticoagulation is warranted. Surgery should be reserved for those who are not responsive or patients in whom the hemodynamic status does not allow delay. Nonresection of the native valve at the initial operation may play a role in the origin of this entity.

  8. Self-Rupturing Hermetic Valve

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    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

  9. One Way--Frustrating, but Rewarding!

    ERIC Educational Resources Information Center

    Yencer, Dick

    1979-01-01

    Describes the experiences of a vocational agriculture teacher who worked for four years with rice farmers in Indonesia. Suggests reasons why changes in farming practices are hard to bring about in developing nations. (LRA)

  10. Threading One's Way Through the Geographic Region.

    ERIC Educational Resources Information Center

    Thomas, Paul F.

    1982-01-01

    Designed for students in grades 7 through 12, the paper presents illustrative resource materials for teaching concepts related to geographic regions. Emphasis is on giving students an understanding of the interrelationship between regional characteristics and human behavior. The paper introduces students to the following notions: environmental…

  11. Secure Introduction of One-way Functions

    DTIC Science & Technology

    2000-07-01

    steps , c terminates in a memory where l h with probability q. By Theorem 4.2, there is a low command c that terminates in no more than pn steps in a memory where with probability at least q. Furthermore, l h since . And because c is low, it has therefore managed to find h without any high variables as input, just occurrences of f h is all. This brings us to the following Corollary: Corollary 4.3 Any bound on the probability of finding h from f h within polynomial time, for a particular integer size and

  12. Telementoring: One Way to Reach America's Students.

    ERIC Educational Resources Information Center

    Foster, Ann

    1999-01-01

    Hewlett Packard has led the telementoring field with its Telementor Program, begun in 1995. The program creates one-to-one mentor relationships between HP employees and grade 5-12 students. Via e-mail, employees currently motivate 1,500 students to excel in math and science and improve communication and problem-solving skills. (MLH)

  13. One-Way Temperature Compensated Fiber Link

    DTIC Science & Technology

    2011-05-01

    individual compensated links. [1] R. Wynands and S. Weyers, “Atomic Fountain Clocks,” Metrologia , vol. 42, pp. S64-S79, 2005. [2] A. D. Ludlow...3] A. Bauch, et al. ,”Comparison Between Frequency Standards oin Europe and the USA at the 10-15 Uncertainty Level,” Metrologia , vol. 43, pp.109

  14. Nose and lungs: one way, one disease

    PubMed Central

    2012-01-01

    It’s well established that asthma, allergic rhinitis and rhinosinusitis are three closely related disease. In pediatrics, these conditions represent a common issue in daily practice. The scientific community has recently started to simply evaluate them as different manifestations of a common pathogenic phenomenon. This consideration relates to important implications in the clinical management of these diseases, which may affect the daily activity of a pediatrician. The unity of the respiratory tract is confirmed both from a morphological and from a functional point of view. When treating rhinitis, it is often necessary to assess the presence of asthma. Patients with sinusitis should be evaluated for a possible concomitant asthma. Conversely, patients with asthma should always be evaluated for possible nasal disease, especially those suffering from difficult-to-treat asthma, in which an occult sinusitis may be detected. The medications that treat nasal diseases appear to be useful in improving asthma control and in reducing bronchial hyperresponsiveness. It seems therefore important to analyze the link between asthma and sinusitis, both in terms of clinical and pathogenic features, as well the therapeutic approach of those patients presenting with these diseases. PMID:23098057

  15. Staphylococcus caprae native mitral valve infective endocarditis

    PubMed Central

    Poyner, Jennifer; Olson, Ewan; Henriksen, Peter; Koch, Oliver

    2016-01-01

    Introduction: Staphylococcus caprae is a rare cause of infective endocarditis. Here, we report a case involving the native mitral valve in the absence of an implantable cardiac electronic device. Case presentation: A 76-year-old man presented with a 2 week history of confusion and pyrexia. His past medical history included an open reduction and internal fixation of a humeral fracture 17 years previously, which remained non-united despite further revision 4 years later. There was no history of immunocompromise or farm-animal contact. Two sets of blood culture bottles, more than 12 h apart, were positive for S. caprae. Trans-thoracic echocardiography revealed a 1×1.2 cm vegetation on the mitral valve, with moderate mitral regurgitation. Due to ongoing confusion, he had a magnetic resonance imaging brain scan, which showed a subacute small vessel infarct consistent with a thromboembolic source. A humeral SPECT-CT (single-photon emission computerized tomography-computerized tomography) scan showed no clear evidence of acute osteomyelitis. Surgical vegetectomy and mitral-valve repair were considered to reduce the risk of further systemic embolism and progressive valve infection. However, the potential risks of surgery to this patient led to a decision to pursue a cure with antibiotic therapy alone. He remained well 3 months after discharge, with repeat echocardiography demonstrating a reduction in the size of the vegetation (0.9 cm). Conclusion: Management of this infection was challenging due to its rarity and its unclear progression, complicated by the dilemma surrounding surgical intervention in a patient with a complex medical background. PMID:28348787

  16. Transcatheter valve-in-valve implantation for failed mitral prosthesis: the first experience in Japan.

    PubMed

    Tada, Norio; Enta, Yusuke; Sakurai, Mie; Ootomo, Tatsushi; Hata, Masaki

    2017-01-01

    An 82-year-old woman had a history of mitral valve replacement with a 25-mm MOSAIC (Medtronic, USA) for severe mitral regurgitation (MR) 8 years previously. Recently, she developed heart failure due to MR secondary to prosthetic valve failure. She underwent transcatheter valve-in-valve implantation with a 23-mm SAPIEN XT (Edwards Lifesciences, USA) to the prosthetic mitral valve by transapical approach. To our knowledge, this is the first reported case of transcatheter valve implantation for failed mitral prosthetic valve using valve-in-valve technique in Japan.

  17. Minimally invasive aortic valve surgery

    PubMed Central

    Castrovinci, Sebastiano; Emmanuel, Sam; Moscarelli, Marco; Murana, Giacomo; Caccamo, Giuseppa; Bertolino, Emanuela Clara; Nasso, Giuseppe; Speziale, Giuseppe; Fattouch, Khalil

    2016-01-01

    Aortic valve disease is a prevalent disorder that affects approximately 2% of the general adult population. Surgical aortic valve replacement is the gold standard treatment for symptomatic patients. This treatment has demonstrably proven to be both safe and effective. Over the last few decades, in an attempt to reduce surgical trauma, different minimally invasive approaches for aortic valve replacement have been developed and are now being increasingly utilized. A narrative review of the literature was carried out to describe the surgical techniques for minimally invasive aortic valve surgery and report the results from different experienced centers. Minimally invasive aortic valve replacement is associated with low perioperative morbidity, mortality and a low conversion rate to full sternotomy. Long-term survival appears to be at least comparable to that reported for conventional full sternotomy. Minimally invasive aortic valve surgery, either with a partial upper sternotomy or a right anterior minithoracotomy provides early- and long-term benefits. Given these benefits, it may be considered the standard of care for isolated aortic valve disease. PMID:27582764

  18. Cavitation guide for control valves

    SciTech Connect

    Tullis, J.P.

    1993-04-01

    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.

  19. Lock Culvert Valves; Hydraulic Design Considerations

    DTIC Science & Technology

    2011-06-01

    lock culvert valves with particular emphasis on reverse tainter valves. Hydraulic coefficients, used to quantify energy losses at valves and the jet...due to a sudden culvert expansion did increase the energy losses in the flow as the jet was dissipated. This additional head loss and associated...8 Figure 5. Loss coefficient for vertical-lift valve having a 45 degree lip

  20. 14 CFR 125.137 - Oil valves.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller,...

  1. 14 CFR 125.137 - Oil valves.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller,...

  2. 14 CFR 125.137 - Oil valves.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller,...

  3. 14 CFR 125.137 - Oil valves.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller,...

  4. 14 CFR 125.137 - Oil valves.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller,...

  5. Thermostatic Radiator Valve Evaluation

    SciTech Connect

    Dentz, J.; Ansanelli, E.

    2015-01-01

    A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market. In this project, the ARIES team sought to better understand the current usage of TRVs by key market players in steam and hot water heating and to conduct limited experiments on the effectiveness of new and old TRVs as a means of controlling space temperatures and reducing heating fuel consumption. The project included a survey of industry professionals, a field experiment comparing old and new TRVs, and cost-benefit modeling analysis using BEopt™ (Building Energy Optimization software).

  6. Stemless ball valve

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    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.

  7. Elastogenesis at the onset of human cardiac valve development

    PubMed Central

    Votteler, Miriam; Berrio, Daniel A. Carvajal; Horke, Alexander; Sabatier, Laetitia; Reinhardt, Dieter P.; Nsair, Ali; Aikawa, Elena; Schenke-Layland, Katja

    2013-01-01

    Semilunar valve leaflets have a well-described trilaminar histoarchitecture, with a sophisticated elastic fiber network. It was previously proposed that elastin-containing fibers play a subordinate role in early human cardiac valve development; however, this assumption was based on data obtained from mouse models and human second and third trimester tissues. Here, we systematically analyzed tissues from human fetal first (4-12 weeks) and second (13-18 weeks) trimester, adolescent (14-19 years) and adult (50-55 years) hearts to monitor the temporal and spatial distribution of elastic fibers, focusing on semilunar valves. Global expression analyses revealed that the transcription of genes essential for elastic fiber formation starts early within the first trimester. These data were confirmed by quantitative PCR and immunohistochemistry employing antibodies that recognize fibronectin, fibrillin 1, 2 and 3, EMILIN1 and fibulin 4 and 5, which were all expressed at the onset of cardiac cushion formation (~week 4 of development). Tropoelastin/elastin protein expression was first detectable in leaflets of 7-week hearts. We revealed that immature elastic fibers are organized in early human cardiovascular development and that mature elastin-containing fibers first evolve in semilunar valves when blood pressure and heartbeat accelerate. Our findings provide a conceptual framework with the potential to offer novel insights into human cardiac valve development and disease. PMID:23637335

  8. Check valve with poppet damping mechanism

    NASA Technical Reports Server (NTRS)

    Morris, Brian G. (Inventor)

    1993-01-01

    An inline check valve for a flow line is presented where the valve element is guided for inline travel forward and rearward of a valve sealing member and is spring biased to a closed sealing condition. One of the guides for the valve element includes a dashpot bore and plunger member to control the rate of travel of the valve element in either direction as well as provided a guiding function. The dashpot is not anchored to the valve body so that the valve can be functional even if the plunger member becomes jammed in the dashpot.

  9. Check valve with poppet damping mechanism

    NASA Astrophysics Data System (ADS)

    Morris, Brian G.

    1993-08-01

    An inline check valve for a flow line is presented where the valve element is guided for inline travel forward and rearward of a valve sealing member and is spring biased to a closed sealing condition. One of the guides for the valve element includes a dashpot bore and plunger member to control the rate of travel of the valve element in either direction as well as provided a guiding function. The dashpot is not anchored to the valve body so that the valve can be functional even if the plunger member becomes jammed in the dashpot.

  10. Check valve with poppet damping mechanism

    NASA Astrophysics Data System (ADS)

    Morris, Brian G.

    1992-06-01

    An inline check valve for a flow line is presented where the valve element is guided for inline travel forward and rearward of a valve sealing member and is spring biased to a closed sealing condition. One of the guides for the valve element includes a dashpot bore and plunger member to control the rate of travel of the valve element in either direction as well as provided a guiding function. The dashpot is not anchored to the valve body so that the valve can be functional even if the plunger member becomes jammed in the dashpot.

  11. Multi-port valve

    DOEpatents

    Lewin, Keith F.

    1997-04-15

    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.

  12. Multi-port valve

    DOEpatents

    Lewin, K.F.

    1997-04-15

    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.

  13. Ferroelectric Fluid Flow Control Valve

    NASA Technical Reports Server (NTRS)

    Jalink, Antony, Jr. (Inventor); Hellbaum, Richard F. (Inventor); Rohrbach, Wayne W. (Inventor)

    1999-01-01

    An active valve is controlled and driven by external electrical actuation of a ferroelectric actuator to provide for improved passage of the fluid during certain time periods and to provide positive closure of the valve during other time periods. The valve provides improved passage in the direction of flow and positive closure in the direction against the flow. The actuator is a dome shaped internally prestressed ferroelectric actuator having a curvature, said dome shaped actuator having a rim and an apex. and a dome height measured from a plane through said rim said apex that varies with an electric voltage applied between an inside and an outside surface of said dome shaped actuator.

  14. Fluid relief and check valve

    DOEpatents

    Blaedel, K.L.; Lord, S.C.; Murray, I.

    1986-07-17

    A passive fluid pressure relief and check valve allows the relief pressure to be slaved to a reference pressure independently of the exhaust pressure. The pressure relief valve is embodied by a submerged vent line in a sealing fluid, the relief pressure being a function of the submerged depth. A check valve is embodied by a vertical column of fluid (the maximum back pressure being a function of the height of the column of fluid). The pressure is vented into an exhaust system which keeps the exhaust out of the area providing the reference pressure.

  15. FLUID PRESSURE AND CAM OPERATED VACUUM VALVE

    DOEpatents

    Batzer, T.H.

    1963-11-26

    An ultra-high vacuum valve that is bakable, reusable, and capable of being quickly opened and closed is described. A translationally movable valve gate having an annular ridge is adapted to contact an annular soft metal gasket disposed at the valve seat such that the soft metal gasket extends beyond the annular ridge on all sides. The valve gate is closed, by first laterally aligning the valve gate with the valve seat and then bringing the valve gate and valve seat into seating contact by the translational movement of a ramp-like wedging means that engages similar ramp-like stractures at the base of the valve gate to force the valve gate into essentially pressureless contact with the annular soft metal gasket. This gasket is then pressurized from beneath by a fluid thereby effecting a vacuura tight seal between the gasket and the ridge. (AEC)

  16. Energy conservation with automatic flow control valves

    SciTech Connect

    Phillips, D.

    1984-12-01

    Automatic flow control valves are offered in a wide range of sizes starting at 1/2 in. with flow rates of 0.5 gpm and up. They are also provided with materials and end connections to meet virtually any fan-coil system requirement. Among these are copper sweat type valves; ductile iron threaded valves; male/female threaded brass valves; and combination flow control/ball valves with union ends.

  17. Innervation of the atrioventricular and semi-lunar heart valves: a review.

    PubMed

    Borin, Christophe; Vanhercke, Daniel; Weyns, Andre

    2006-08-01

    Heart valves were historically considered passive structures that function through the haemodynamic forces created by the contraction and relaxation of the myocardium. However, research into valvular structures has revealed that heart valves are very complex, specialized structures that contain both smooth muscle cells and nerve fibres. This is particularly true for the atrioventricular valves, which are by far the most well studied to date. The various heart valves have been shown to contract independently during different moments of the heart cycle, suggesting that compensatory adaptation mechanisms exist to mediate the timing and efficacy of heart valve closure. These adaptations occur via different mechanisms, including neural mechanisms that influence the heart valves. Accumulating evidence continues to improve our understanding of the nerve fibres in the heart (adrenergic, cholinergic, etc.). Future studies will no doubt add to this exciting picture. Here, we review the current morphological knowledge of human and animal heart valve innervation, including discussions of the chordae tendineae and the papillary muscles, as well as the differences between the atrioventricular (AV) valves and the semi-lunar (SL) valves.

  18. Implantation of a Tissue-Engineered Tubular Heart Valve in Growing Lambs.

    PubMed

    Reimer, Jay; Syedain, Zeeshan; Haynie, Bee; Lahti, Matthew; Berry, James; Tranquillo, Robert

    2017-02-01

    Current pediatric heart valve replacement options are suboptimal because they are incapable of somatic growth. Thus, children typically have multiple surgeries to replace outgrown valves. In this study, we present the in vivo function and growth potential of our tissue-engineered pediatric tubular valve. The valves were fabricated by sewing two decellularized engineered tissue tubes together in a prescribed pattern using degradable sutures and subsequently implanted into the main pulmonary artery of growing lambs. Valve function was monitored using periodic ultrasounds after implantation throughout the duration of the study. The valves functioned well up to 8 weeks, 4 weeks beyond the suture strength half-life, after which their insufficiency index worsened. Histology from the explanted valves revealed extensive host cell invasion within the engineered root and commencing from the leaflet surfaces. These cells expressed multiple phenotypes, including endothelial, and deposited elastin and collagen IV. Although the tubes fused together along the degradable suture line as designed, the leaflets shortened compared to their original height. This shortening is hypothesized to result from inadequate fusion at the commissures prior to suture degradation. With appropriate commissure reinforcement, this novel heart valve may provide the somatic growth potential desired for a pediatric valve replacement.

  19. Diseases of the Tricuspid Valve

    MedlinePlus

    ... Kawasaki Disease Long Q-T Syndrome Marfan Syndrome Metabolic Syndrome Mitral Valve Prolapse Myocardial Bridge Myocarditis Obstructive Sleep Apnea Pericarditis Peripheral Vascular Disease Rheumatic Fever Sick Sinus Syndrome Silent Ischemia Stroke Sudden ...

  20. What Is Heart Valve Surgery?

    MedlinePlus

    ... valve separates the left ventricle (your heart’s main pumping chamber) and the aorta (the major artery that ... surgery, you‘ll go to an intensive care unit (ICU). •Your family can visit you briefly in ...

  1. Simpler valve for reciprocating engines

    NASA Technical Reports Server (NTRS)

    Akkerman, J. W.

    1978-01-01

    Simpler design eliminating camshafts, cams, and mechanical springs should improve reliability of hydrazine powered reciprocating engines. Valve is expected to improve efficiency, and reduce weight of engines in range up to 50 horsepower.

  2. Mitral Valve Prolapse (For Parents)

    MedlinePlus

    ... Atrial Septal Defect Ventricular Septal Defect Heart and Circulatory System Congenital Heart Defects Getting an EKG (Video) Your Heart & Circulatory System Heart Murmurs Marfan Syndrome Mitral Valve Prolapse EKG ( ...

  3. Bipropellant shut-off valve

    NASA Technical Reports Server (NTRS)

    Smith, J. V.

    1971-01-01

    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.

  4. Nontuberculous Mycobacteria: An Underestimated Cause of Bioprosthetic Valve Infective Endocarditis

    PubMed Central

    Bouchiat, Coralie; Saison, Julien; Boisset, Sandrine; Flandrois, Jean-Pierre; Issartel, Bertrand; Dauwalder, Olivier; Benito, Yvonne; Jarraud, Sophie; Grando, Jacqueline; Boibieux, Andre; Dumitrescu, Oana; Delahaye, François; Farhat, Fadi; Thivolet-Bejui, Françoise; Frieh, Jean-Philippe; Vandenesch, François

    2015-01-01

    Background. Atypical mycobacteria, or nontuberculous mycobacteria (NTM), have been barely reported as infective endocarditis (IE) agents. Methods. From January 2010 to December 2013, cardiac valve samples sent to our laboratory as cases of blood culture-negative suspected IE were analyzed by 16S rDNA polymerase chain reaction (PCR). When positive for NTM, hsp PCR allowed species identification. Demographic, clinical, echocardiographic, histopathological, and Ziehl-Neelsen staining data were then collected. Results. Over the study period, 6 of 370 cardiac valves (belonging to 5 patients in 3 hospitals) were positive for Mycobacterium chelonae (n = 5) and Mycobacterium lentiflavum (n = 1) exclusively on bioprosthetic material. The 5 patients presented to the hospital for heart failure without fever 7.1–18.9 months (median 13.1 months) after biological prosthetic valve implantation. Echocardiography revealed paravalvular regurgitation due to prosthesis dehiscence in all patients. Histopathological examination of the explanted material revealed inflammatory infiltrates in all specimens, 3 of which were associated with giant cells. Gram staining and conventional cultures remained negative, whereas Ziehl-Neelsen staining showed acid-fast bacilli in all patients. Allergic etiology was ruled out by antiporcine immunoglobulin E dosages. These 5 cases occurred exclusively on porcine bioprosthetic material, revealing a statistically significant association between bioprosthetic valves and NTM IE (P < .001). Conclusions. The body of evidence confirmed the diagnosis of prosthetic IE. The statistically significant association between bioprosthetic valves and NTM IE encourages systematic Ziehl-Neelsen staining of explanted bioprosthetic valves in case of early bioprosthesis dysfunction, even without an obvious sign of IE. In addition, we strongly question the cardiac bioprosthesis conditioning process after animal sacrifice. PMID:26213691

  5. Liquid-blocking check valve

    DOEpatents

    Merrill, J.T.

    1982-09-27

    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.

  6. Prosthetic valve endocarditis. A survey.

    PubMed Central

    Ben Ismail, M; Hannachi, N; Abid, F; Kaabar, Z; Rougé, J F

    1987-01-01

    Fifty eight patients (aged 8-59 years, mean 27) treated for prosthetic valve endocarditis from January 1966 to January 1985 were studied retrospectively by review of case notes. There were 12 cases of early and 46 cases of late prosthetic valve endocarditis. These developed in 28 patients with an isolated aortic valve, in 26 with an isolated mitral valve, and in four with both aortic and mitral prosthetic valves. Streptococci were the most commonly isolated microorganisms, followed by staphylococci, Gram negative bacteria, and fungi. A surgical (34 cases) or a necropsy specimen (10 cases) from 44 cases was examined. Eighty two per cent of the patients had congestive heart failure. Twenty four of the 58 patients were medically treated and 17 died (70% mortality). Combined medical and surgical treatment was used in 34 patients; the main indication for surgery was congestive heart failure. Fourteen patients on combined treatment died (40% mortality). Persistent sepsis and prosthetic valve dehiscence were the most common early and late operative complications. The most important influences on outcome were congestive heart failure, the type of micro-organism, the severity and extent of anatomical lesions, the time of onset of prosthetic valve endocarditis, and the type of treatment. This survey indicates that only patients without congestive heart failure or embolic complications and with sensitive micro-organism should be treated medically. In view of the poor prognosis patients with prosthetic valve endocarditis associated with congestive heart failure, persistent sepsis, and repeat arterial emboli should be treated by early surgical intervention. PMID:3620246

  7. Facts and fiction surrounding the discovery of the venous valves.

    PubMed

    Scultetus, A H; Villavicencio, J L; Rich, N M

    2001-02-01

    circulation. Therefore, our investigations revealed that Estienne and Canano discovered the venous valves in the 1530s. Fabricius ab Aquapendente's achievement was their full recognition 64 years later. However, it was not until 1628 that their function was fully understood, with the discovery of the blood circulation by William Harvey.

  8. Perivalvular pannus and valve thrombosis: two concurrent mechanisms of mechanical valve prosthesis dysfunction.

    PubMed

    Arnáiz-García, María Elena; González-Santos, Jose María; Bueno-Codoñer, María E; López-Rodríguez, Javier; Dalmau-Sorlí, María José; Arévalo-Abascal, Adolfo; Arribas-Jiménez, Antonio; Diego-Nieto, Alejandro; Rodríguez-Collado, Javier; Rodríguez-López, Jose María

    2015-02-01

    A 78-year-old woman was admitted to our institution with progressive dyspnea. She had previously been diagnosed with rheumatic heart disease and had undergone cardiac surgery for mechanical mitral valve replacement ten years previously. Transesophageal echocardiography revealed blockage of the mechanical prosthesis and the patient was scheduled for surgery, in which a thrombus was removed from the left atrial appendage. A partial thrombosis of the mechanical prosthesis and circumferential pannus overgrowth were concomitantly detected. Prosthetic heart valve blockage is a rare but life-threatening complication, the main causes of which are thrombosis and pannus formation. The two conditions are different but both are usually misdiagnosed. Two concurrent mechanisms of prosthesis blockage were found in this patient.

  9. Bilateral epididymitis in a child with undiagnosed posterior urethral valves.

    PubMed

    Kwong, Justin; Lorenzo, Armando J; DeMaria, Jorge; Braga, Luis H P

    2013-07-01

    Posterior urethral valves are most commonly detected in the early neonatal period, the diagnosis often antenatally suspected from ultrasound findings. Nevertheless, some cases might go undetected and become manifest later in life with lower urinary tract symptoms. We describe the unusual case of a 5-year-old boy with a 2-month history of bladder distension, urinary dribbling, and epididymitis. Cystourethrography revealed posterior urethral valves with reflux into the seminal vesicles, vas deferens, and epididymis, bilaterally. A review of the published data is provided in the context of this unusual presentation pattern.

  10. Biological and mechanical evaluation of a Bio-Hybrid scaffold for autologous valve tissue engineering.

    PubMed

    Jahnavi, S; Saravanan, U; Arthi, N; Bhuvaneshwar, G S; Kumary, T V; Rajan, S; Verma, R S

    2017-04-01

    Major challenge in heart valve tissue engineering for paediatric patients is the development of an autologous valve with regenerative capacity. Hybrid tissue engineering approach is recently gaining popularity to design scaffolds with desired biological and mechanical properties that can remodel post implantation. In this study, we fabricated aligned nanofibrous Bio-Hybrid scaffold made of decellularized bovine pericardium: polycaprolactone-chitosan with optimized polymer thickness to yield the desired biological and mechanical properties. CD44(+), αSMA(+), Vimentin(+) and CD105(-) human valve interstitial cells were isolated and seeded on these Bio-Hybrid scaffolds. Subsequent biological evaluation revealed interstitial cell proliferation with dense extra cellular matrix deposition that indicated the viability for growth and proliferation of seeded cells on the scaffolds. Uniaxial mechanical tests along axial direction showed that the Bio-Hybrid scaffolds has at least 20 times the strength of the native valves and its stiffness is nearly 3 times more than that of native valves. Biaxial and uniaxial mechanical studies on valve interstitial cells cultured Bio-Hybrid scaffolds revealed that the response along the axial and circumferential direction was different, similar to native valves. Overall, our findings suggest that Bio-Hybrid scaffold is a promising material for future development of regenerative heart valve constructs in children.

  11. Right atrial myxoma arising from the Eustachian valve in a patient with colonic polyposis.

    PubMed

    Bonde, Pramod; Sachithanandan, Anand; Graham, Alastair N J; Richardson, S Geoffery; Gladstone, Dennis J

    2002-07-01

    Right atrial myxoma arising from the Eustachian valve is rare, with only two reported cases; moreover, any association with colonic polyps is uncommon, with only one such case documented. A case is described of a 68-year-old male who presented with chronic anemia; an initial investigation revealed colonic polyps, but anemia persisted after polypectomy. Further investigation revealed a right atrial myxoma arising from the Eustachian valve and prolapsing into the right ventricle through the tricuspid valve. After successful removal of the lesion, hematological indices returned to normal. In cases of persisting anemia, other rare causes such as atrial myxoma should be sought.

  12. Noninvasive valve monitor using alternating electromagnetic field

    DOEpatents

    Eissenberg, David M.; Haynes, Howard D.; Casada, Donald A.

    1993-01-01

    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.

  13. Noninvasive valve monitor using alternating electromagnetic field

    DOEpatents

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

    1993-03-16

    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.

  14. Development of an effective valve packing program

    SciTech Connect

    Hart, K.A.

    1996-12-01

    Current data now shows that graphite valve packing installed within the guidance of a controlled program produces not only reliable stem sealing but predictable running loads. By utilizing recent technological developments in valve performance monitoring for both MOV`s and AOV`s, valve packing performance can be enhanced while reducing maintenance costs. Once known, values are established for acceptable valve packing loads, the measurement of actual valve running loads via the current MOV/AOV diagnostic techniques can provide indication of future valve stem sealing problems, improper valve packing installation or identify the opportunity for valve packing program improvements. At times the full benefit of these advances in material and predictive technology remain under utilized due to simple past misconceptions associated with valve packing. This paper will explore the basis for these misconceptions, provide general insight into the current understanding of valve packing and demonstrate how with this new understanding and current valve diagnostic equipment the key aspects required to develop an effective, quality valve packing program fit together. The cost and operational benefits provided by this approach can be significant impact by the: elimination of periodic valve repacking, reduction of maintenance costs, benefits of leak-free valve operation, justification for reduced Post Maintenance Test Requirements, reduced radiation exposure, improved plant appearance.

  15. Dissection of the atrial wall after mitral valve replacement.

    PubMed Central

    Lukács, L; Kassai, I; Lengyel, M

    1996-01-01

    We describe an unusual sequela of mitral valve replacement in a 50-year-old woman who had undergone a closed mitral commissurotomy in 1975. She was admitted to our hospital because of mitral restenosis in November 1993, at which time her mitral valve was replaced with a mechanical prosthesis. On the 8th postoperative day, the patient developed symptoms of heart failure; transesophageal echocardiography revealed dissection and rupture of the left atrial wall. At prompt reoperation, we found an interlayer dissection and rupture of the atrial wall into the left atrium. We repaired the ruptured atrial wall with a prosthetic patch. The postoperative course was uneventful, and postoperative transesophageal echocardiography showed normal prosthetic valve function and no dissection. Images PMID:8680278

  16. Ischemic mitral valve prolapse

    PubMed Central

    Cristiano, Spadaccio; Nenna, Antonio; Chello, Massimo

    2016-01-01

    Ischemic mitral prolapse (IMP) is a pathologic entity encountered in about one-third among the patients undergoing surgery for ischemic mitral regurgitation (IMR). IMP is generally the result of a papillary muscle injury consequent to myocardial, but the recent literature is progressively unveiling a more complex pathogenesis. The mechanisms underlying its development regards the impairment of one or more components of the mitral apparatus, which comprises the annulus, the chordae tendineae, the papillary muscle and the left ventricular wall. IMP is not only a disorder of valvular function, but also entails coexistent aspects of a geometric disturbance of the mitral valve configuration and of the left ventricular function and dimension and a correct understanding of all these aspects is crucial to guide and tailor the correct therapeutic strategy to be adopted. Localization of prolapse, anatomic features of the prolapsed leaflets and the subvalvular apparatus should be carefully evaluated as also constituting the major determinants defining patient’s outcomes. This review will summarize our current understanding of the pathophysiology and clinical evidence on IMP with a particular focus on the surgical treatment. PMID:28149574

  17. Valve-less microdispenser

    NASA Astrophysics Data System (ADS)

    Tan, Ming Kwang; Xin, Wang; Lee, Weng Kent

    2015-11-01

    We demonstrate the concept of valve-less microdispenser to control of the liquid flow through the nozzle, by incorporating Leidenfrost effect into the nozzle design. When the nozzle is heated above the Leidenfrost point, a thin vapor layer is formed between the heated substrate and the liquid above it. The vapor pressure due to the presence of the vapor layer, together with the effect of surface tension of the liquid, exerted on the liquid-vapor interface, preventing the flow of the liquid through the nozzle. The experimental results shown that nozzles of diameter 400 micrometer and below, the nozzle temperature of 150 degree Celsius is sufficient to prevent the continuous flowing of the liquid, whereas for nozzles of diameter between 400 to 500 micrometer, the nozzle temperature needs to increase to 160 degree Celsius in order to prevent the continuous flowing of the liquid. When nozzle temperature below 160 degree Celsius, intermittent ejection of microdroplets, whose size is a function of nozzle temperature, is observed.

  18. Annular flow diverter valve

    DOEpatents

    Rider, Robert L.

    1980-01-01

    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.

  19. Multi-Element Unstructured Analyses of Complex Valve Systems

    NASA Technical Reports Server (NTRS)

    Sulyma, Peter (Technical Monitor); Ahuja, Vineet; Hosangadi, Ashvin; Shipman, Jeremy

    2004-01-01

    The safe and reliable operation of high pressure test stands for rocket engine and component testing places an increased emphasis on the performance of control valves and flow metering devices. In this paper, we will present a series of high fidelity computational analyses of systems ranging from cryogenic control valves and pressure regulator systems to cavitating venturis that are used to support rocket engine and component testing at NASA Stennis Space Center. A generalized multi-element framework with sub-models for grid adaption, grid movement and multi-phase flow dynamics has been used to carry out the simulations. Such a framework provides the flexibility of resolving the structural and functional complexities that are typically associated with valve-based high pressure feed systems and have been difficult to deal with traditional CFD methods. Our simulations revealed a rich variety of flow phenomena such as secondary flow patterns, hydrodynamic instabilities, fluctuating vapor pockets etc. In the paper, we will discuss performance losses related to cryogenic control valves, and provide insight into the physics of the dominant multi-phase fluid transport phenomena that are responsible for the choking like behavior in cryogenic control elements. Additionally, we will provide detailed analyses of the modal instability that is observed in the operation of the dome pressure regulator valve. Such instabilities are usually not localized and manifest themselves as a system wide phenomena leading to an undesirable chatter at high flow conditions.

  20. Comparative hemodynamics in an aorta with bicuspid and trileaflet valves

    NASA Astrophysics Data System (ADS)

    Gilmanov, Anvar; Sotiropoulos, Fotis

    2016-04-01

    Bicuspid aortic valve (BAV) is a congenital heart defect that has been associated with serious aortopathies, such as aortic stenosis, aortic regurgitation, infective endocarditis, aortic dissection, calcific aortic valve and dilatation of ascending aorta. There are two main hypotheses to explain the increase prevalence of aortopathies in patients with BAV: the genetic and the hemodynamic. In this study, we seek to investigate the possible role of hemodynamic factors as causes of BAV-associated aortopathy. We employ the curvilinear immersed boundary method coupled with an efficient thin-shell finite-element formulation for tissues to carry out fluid-structure interaction simulations of a healthy trileaflet aortic valve (TAV) and a BAV placed in the same anatomic aorta. The computed results reveal major differences between the TAV and BAV flow patterns. These include: the dynamics of the aortic valve vortex ring formation and break up; the large-scale flow patterns in the ascending aorta; the shear stress magnitude, directions, and dynamics on the heart valve surfaces. The computed results are in qualitative agreement with in vivo magnetic resonance imaging data and suggest that the linkages between BAV aortopathy and hemodynamics deserve further investigation.

  1. Asymptomatic Strut Fracture in DeBakey-Surgitool Aortic Valves

    PubMed Central

    Von Der Emde, Jürgen; Eberlein, Ulrich; Breme, Jürgen

    1990-01-01

    From August 1971 through November 1972, we implanted 62 Model 2 DeBakey-Surgitool aortic valve prostheses in 62 patients, 4 of whom later had clinically asymptomatic strut fractures. In 1 case, the patient died suddenly, and autopsy revealed detachment of the ball-cage; in each of the other 3 cases, fractures of 2 struts close to the base of the prosthesis were diagnosed fluoroscopically, and the patients underwent successful reoperation. The interval between implantation and reoperation ranged from 11 months to 16 years, 9 months. In 1 patient, retrospective study of chest radiographs revealed that the fracture had been present for 2½ years. Larger valves (≥ A6) were affected significantly more often than smaller ones. We performed metallurgic analysis of 1 prosthesis: results revealed strut wear from fatigue cracking and secondary abrasion. Strut fracture was also promoted by suspension of the cage at right angles to the prosthetic ring and by use of a pyrolytic carbon ball in a titanium cage (i.e., an occluder harder than its holder). Patients with DeBakey-Surgitool aortic valve prostheses should undergo annual radiologic examinations to enable early detection of strut fractures. Prophylactic valve replacement is not indicated. (Texas Heart Institute Journal 1990;17:223-7) Images PMID:15227175

  2. Spring-Loaded Joule-Thomson Valve

    NASA Technical Reports Server (NTRS)

    Jones, J. A.; Britcliffe, M. J.

    1986-01-01

    Improved design reduces clogging and maintains constant pressure drop as flow rate varies. Spring-Loaded Joule-Thomson Valve pressure drop regulated by spring pushing stainless-steel ball against soft brass seat. Pressure drop remains nearly constant, regardless of helium flow rate and of any gas contaminants frozen on valve seat. Because springloaded J-T valve maintains constant pressure drop, upstream roomtemperature throttle valve adjusts flow rate precisely for any given upstream pressure. In addition, new valve relatively invulnerable to frozen gas contaminants, which clog fixed-orifice J-T valves.

  3. Valve system incorporating single failure protection logic

    DOEpatents

    Ryan, Rodger; Timmerman, Walter J. H.

    1980-01-01

    A valve system incorporating single failure protective logic. The system consists of a valve combination or composite valve which allows actuation or de-actuation of a device such as a hydraulic cylinder or other mechanism, integral with or separate from the valve assembly, by means of three independent input signals combined in a function commonly known as two-out-of-three logic. Using the input signals as independent and redundant actuation/de-actuation signals, a single signal failure, or failure of the corresponding valve or valve set, will neither prevent the desired action, nor cause the undesired action of the mechanism.

  4. Rheumatic Heart Disease and Myxomatous Degeneration: Differences and Similarities of Valve Damage Resulting from Autoimmune Reactions and Matrix Disorganization

    PubMed Central

    Martins, Carlo de Oliveira; Demarchi, Lea; Ferreira, Frederico Moraes; Pomerantzeff, Pablo Maria Alberto; Brandao, Carlos; Sampaio, Roney Orismar; Spina, Guilherme Sobreira; Kalil, Jorge; Cunha-Neto, Edecio

    2017-01-01

    Autoimmune inflammatory reactions leading to rheumatic fever (RF) and rheumatic heart disease (RHD) result from untreated Streptococcus pyogenes throat infections in individuals who exhibit genetic susceptibility. Immune effector mechanisms have been described that lead to heart tissue damage culminating in mitral and aortic valve dysfunctions. In myxomatous valve degeneration (MXD), the mitral valve is also damaged due to non-inflammatory mechanisms. Both diseases are characterized by structural valve disarray and a previous proteomic analysis of them has disclosed a distinct profile of matrix/structural proteins differentially expressed. Given their relevance in organizing valve tissue, we quantitatively evaluated the expression of vimentin, collagen VI, lumican, and vitronectin as well as performed immunohistochemical analysis of their distribution in valve tissue lesions of patients in both diseases. We identified abundant expression of two isoforms of vimentin (45 kDa, 42 kDa) with reduced expression of the full-size protein (54 kDa) in RHD valves. We also found increased vitronectin expression, reduced collagen VI expression and similar lumican expression between RHD and MXD valves. Immunohistochemical analysis indicated disrupted patterns of these proteins in myxomatous degeneration valves and disorganized distribution in rheumatic heart disease valves that correlated with clinical manifestations such as valve regurgitation or stenosis. Confocal microscopy analysis revealed a diverse pattern of distribution of collagen VI and lumican into RHD and MXD valves. Altogether, these results demonstrated distinct patterns of altered valve expression and tissue distribution/organization of structural/matrix proteins that play important pathophysiological roles in both valve diseases. PMID:28121998

  5. Rheumatic Heart Disease and Myxomatous Degeneration: Differences and Similarities of Valve Damage Resulting from Autoimmune Reactions and Matrix Disorganization.

    PubMed

    Martins, Carlo de Oliveira; Demarchi, Lea; Ferreira, Frederico Moraes; Pomerantzeff, Pablo Maria Alberto; Brandao, Carlos; Sampaio, Roney Orismar; Spina, Guilherme Sobreira; Kalil, Jorge; Cunha-Neto, Edecio; Guilherme, Luiza

    2017-01-01

    Autoimmune inflammatory reactions leading to rheumatic fever (RF) and rheumatic heart disease (RHD) result from untreated Streptococcus pyogenes throat infections in individuals who exhibit genetic susceptibility. Immune effector mechanisms have been described that lead to heart tissue damage culminating in mitral and aortic valve dysfunctions. In myxomatous valve degeneration (MXD), the mitral valve is also damaged due to non-inflammatory mechanisms. Both diseases are characterized by structural valve disarray and a previous proteomic analysis of them has disclosed a distinct profile of matrix/structural proteins differentially expressed. Given their relevance in organizing valve tissue, we quantitatively evaluated the expression of vimentin, collagen VI, lumican, and vitronectin as well as performed immunohistochemical analysis of their distribution in valve tissue lesions of patients in both diseases. We identified abundant expression of two isoforms of vimentin (45 kDa, 42 kDa) with reduced expression of the full-size protein (54 kDa) in RHD valves. We also found increased vitronectin expression, reduced collagen VI expression and similar lumican expression between RHD and MXD valves. Immunohistochemical analysis indicated disrupted patterns of these proteins in myxomatous degeneration valves and disorganized distribution in rheumatic heart disease valves that correlated with clinical manifestations such as valve regurgitation or stenosis. Confocal microscopy analysis revealed a diverse pattern of distribution of collagen VI and lumican into RHD and MXD valves. Altogether, these results demonstrated distinct patterns of altered valve expression and tissue distribution/organization of structural/matrix proteins that play important pathophysiological roles in both valve diseases.

  6. Application of Tracking and Data Relay Satellite (TDRS) Differenced One-Way Doppler (DOWD) Tracking Data for Orbit Determination and Station Acquisition Support of User Spacecraft Without TDRS Compatible Transponders

    NASA Technical Reports Server (NTRS)

    Olszewski, A. D., Jr.; Wilcox, T. P.; Beckman, Mark

    1996-01-01

    Many spacecraft are launched today with only an omni-directional (omni) antenna and do not have an onboard Tracking and Data Relay Satellite (TDRS) transponder that is capable of coherently returning a carrier signal through TDRS. Therefore, other means of tracking need to be explored and used to adequately acquire the spacecraft. Differenced One-Way Doppler (DOWD) tracking data are very useful in eliminating the problems associated with the instability of the onboard oscillators when using strictly one-way Doppler data. This paper investigates the TDRS DOWD tracking data received by the Goddard Space Flight Center (GSFC) Flight Dynamics Facility (FDF) during the launch and early orbit phases for the the Interplanetary Physics Laboratory (WIND) and the National Oceanographic and Atmospheric Administration (NOAA)-J missions. In particular FDF personnel performed an investigation of the data residuals and made an assessment of the acquisition capabilities of DOWD-based solutions. Comparisons of DOWD solutions with existing data types were performed and analyzed in this study. The evaluation also includes atmospheric editing of the DOWD data and a study of the feasibility of solving for Doppler biases in an attempt to minimize error. Furthermore, by comparing the results from WIND and NOAA-J, an attempt is made to show the limitations involved in using DOWD data for the two different mission profiles. The techniques discussed in this paper benefit the launches of spacecraft that do not have TDRS transponders on board, particularly those launched into a low Earth orbit. The use of DOWD data is a valuable asset to missions which do not have a stable local oscillator to enable high-quality solutions from the one-way/return-link Doppler tracking data.

  7. 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

  8. klf2a couples mechanotransduction and zebrafish valve morphogenesis through fibronectin synthesis

    PubMed Central

    Steed, Emily; Faggianelli, Nathalie; Roth, Stéphane; Ramspacher, Caroline; Concordet, Jean-Paul; Vermot, Julien

    2016-01-01

    The heartbeat and blood flow signal to endocardial cell progenitors through mechanosensitive proteins that modulate the genetic program controlling heart valve morphogenesis. To date, the mechanism by which mechanical forces coordinate tissue morphogenesis is poorly understood. Here we use high-resolution imaging to uncover the coordinated cell behaviours leading to heart valve formation. We find that heart valves originate from progenitors located in the ventricle and atrium that generate the valve leaflets through a coordinated set of endocardial tissue movements. Gene profiling analyses and live imaging reveal that this reorganization is dependent on extracellular matrix proteins, in particular on the expression of fibronectin1b. We show that blood flow and klf2a, a major endocardial flow-responsive gene, control these cell behaviours and fibronectin1b synthesis. Our results uncover a unique multicellular layering process leading to leaflet formation and demonstrate that endocardial mechanotransduction and valve morphogenesis are coupled via cellular rearrangements mediated by fibronectin synthesis. PMID:27221222

  9. Single-use thermoplastic microfluidic burst valves enabling on-chip reagent storage.

    PubMed

    Rahmanian, Omid D; DeVoe, Don L

    2015-05-01

    A simple and reliable method for fabricating single-use normally closed burst valves in thermoplastic microfluidic devices is presented, using a process flow that is readily integrated into established workflows for the fabrication of thermoplastic microfluidics. An experimental study of valve performance reveals the relationships between valve geometry and burst pressure. The technology is demonstrated in a device employing multiple valves engineered to actuate at different inlet pressures that can be generated using integrated screw pumps. On-chip storage and reconstitution of fluorescein salt sealed within defined reagent chambers are demonstrated. By taking advantage of the low gas and water permeability of cyclic olefin copolymer, the robust burst valves allow on-chip hermetic storage of reagents, making the technology well suited for the development of integrated and disposable assays for use at the point of care.

  10. Experiment and numerical simulation of cavitation performance on a pressure-regulating valve with different openings

    NASA Astrophysics Data System (ADS)

    Qu, W. S.; Tan, L.; Cao, S. L.; Xu, Y.; Huang, J.; Xu, Q. H.

    2015-01-01

    As a kind of widely used device in pipe system for pressure and flow rate regulating, the valve would experience cavitation in the case when a sharp pressure drop occurs, which will induce the energy loss, noise and vibration of pipeline system, and even operational accidents. The experiment on flow resistance coefficient of a DN600 pressure-regulating valve under operation conditions from 0% to 100% openings is conducted. Based on the RNG k-e turbulence model and the Rayleigh-Plesset cavitation equation, a set of computational model is developed to simulate the turbulent flow in the valve under operational conditions from 0% to 100% openings. The computational results of flow resistance coefficient are compared to the experimental data. And the numerical simulation is employed to predict the cavitation performance of the valve at different inlet flow conditions. The transient cavitating flow is calculated to reveal the time evolution of cavitation in the valve.

  11. Analysis of Complex Valve and Feed Systems

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    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.

  12. FLUID MECHANICS OF ARTIFICIAL HEART VALVES

    PubMed Central

    Dasi, Lakshmi P; Simon, Helene A; Sucosky, Philippe; Yoganathan, Ajit P

    2009-01-01

    SUMMARY 1. Artificial heart valves have been in use for over five decades to replace diseased heart valves. Since the first heart valve replacement performed with a caged-ball valve, more than 50 valve designs have been developed, differing principally in valve geometry, number of leaflets and material. To date, all artificial heart valves are plagued with complications associated with haemolysis, coagulation for mechanical heart valves and leaflet tearing for tissue-based valve prosthesis. For mechanical heart valves, these complications are believed to be associated with non-physiological blood flow patterns. 2. In the present review, we provide a bird’s-eye view of fluid mechanics for the major artificial heart valve types and highlight how the engineering approach has shaped this rapidly diversifying area of research. 3. Mechanical heart valve designs have evolved significantly, with the most recent designs providing relatively superior haemodynamics with very low aerodynamic resistance. However, high shearing of blood cells and platelets still pose significant design challenges and patients must undergo life-long anticoagulation therapy. Bioprosthetic or tissue valves do not require anticoagulants due to their distinct similarity to the native valve geometry and haemodynamics, but many of these valves fail structurally within the first 10–15 years of implantation. 4. These shortcomings have directed present and future research in three main directions in attempts to design superior artificial valves: (i) engineering living tissue heart valves; (ii) development of advanced computational tools; and (iii) blood experiments to establish the link between flow and blood damage. PMID:19220329

  13. Differential MicroRNA Expression Profile in Myxomatous Mitral Valve Prolapse and Fibroelastic Deficiency Valves.

    PubMed

    Chen, Yei-Tsung; Wang, Juan; Wee, Abby S Y; Yong, Quek-Wei; Tay, Edgar Lik-Wui; Woo, Chin Cheng; Sorokin, Vitaly; Richards, Arthur Mark; Ling, Lieng-Hsi

    2016-05-18

    Myxomatous mitral valve prolapse (MMVP) and fibroelastic deficiency (FED) are two common variants of degenerative mitral valve disease (DMVD), which is a leading cause of mitral regurgitation worldwide. While pathohistological studies have revealed differences in extracellular matrix content in MMVP and FED, the molecular mechanisms underlying these two disease entities remain to be elucidated. By using surgically removed valvular specimens from MMVP and FED patients that were categorized on the basis of echocardiographic, clinical and operative findings, a cluster of microRNAs that expressed differentially were identified. The expressions of has-miR-500, -3174, -17, -1193, -646, -1273e, -4298, -203, -505, and -939 showed significant differences between MMVP and FED after applying Bonferroni correction (p < 0.002174). The possible involvement of microRNAs in the pathogenesis of DMVD were further suggested by the presences of in silico predicted target sites on a number of genes reported to be involved in extracellular matrix homeostasis and marker genes for cellular composition of mitral valves, including decorin (DCN), aggrecan (ACAN), fibromodulin (FMOD), α actin 2 (ACTA2), extracellular matrix protein 2 (ECM2), desmin (DES), endothelial cell specific molecule 1 (ESM1), and platelet/ endothelial cell adhesion molecule 1 (PECAM1), as well as inverse correlations of selected microRNA and mRNA expression in MMVP and FED groups. Our results provide evidence that distinct molecular mechanisms underlie MMVP and FED. Moreover, the microRNAs identified may be targets for the future development of diagnostic biomarkers and therapeutics.

  14. Differential MicroRNA Expression Profile in Myxomatous Mitral Valve Prolapse and Fibroelastic Deficiency Valves

    PubMed Central

    Chen, Yei-Tsung; Wang, Juan; Wee, Abby S. Y.; Yong, Quek-Wei; Tay, Edgar Lik-Wui; Woo, Chin Cheng; Sorokin, Vitaly; Richards, Arthur Mark; Ling, Lieng-Hsi

    2016-01-01

    Myxomatous mitral valve prolapse (MMVP) and fibroelastic deficiency (FED) are two common variants of degenerative mitral valve disease (DMVD), which is a leading cause of mitral regurgitation worldwide. While pathohistological studies have revealed differences in extracellular matrix content in MMVP and FED, the molecular mechanisms underlying these two disease entities remain to be elucidated. By using surgically removed valvular specimens from MMVP and FED patients that were categorized on the basis of echocardiographic, clinical and operative findings, a cluster of microRNAs that expressed differentially were identified. The expressions of has-miR-500, -3174, -17, -1193, -646, -1273e, -4298, -203, -505, and -939 showed significant differences between MMVP and FED after applying Bonferroni correction (p < 0.002174). The possible involvement of microRNAs in the pathogenesis of DMVD were further suggested by the presences of in silico predicted target sites on a number of genes reported to be involved in extracellular matrix homeostasis and marker genes for cellular composition of mitral valves, including decorin (DCN), aggrecan (ACAN), fibromodulin (FMOD), α actin 2 (ACTA2), extracellular matrix protein 2 (ECM2), desmin (DES), endothelial cell specific molecule 1 (ESM1), and platelet/ endothelial cell adhesion molecule 1 (PECAM1), as well as inverse correlations of selected microRNA and mRNA expression in MMVP and FED groups. Our results provide evidence that distinct molecular mechanisms underlie MMVP and FED. Moreover, the microRNAs identified may be targets for the future development of diagnostic biomarkers and therapeutics. PMID:27213335

  15. Mechanical heart valve cavitation in patients with bileaflet valves.

    PubMed

    Johansen, Peter; Andersen, Tina S; Hasenkam, J Michael; Nygaard, Hans; Paulsen, Peter K

    2014-01-01

    Today, the quality of mechanical heart valves is quite high, and implantation has become a routine clinical procedure with a low operative mortality (< 5%). However, patients still face the risks of blood cell damage, thromboembolic events, and material failure of the prosthetic device. One mechanism found to be a possible contributor to these adverse effects is cavitation. In vitro, cavitation has been directly demonstrated by visualization and indirectly in vivo by registering of high frequency pressure fluctuations (HFPF). Tilting disc valves are thought of having higher cavitation potential than bileaflet valves due to higher closing velocities. However, the thromboembolic potential seems to be the same. Further studies are therefore needed to investigate the cavitation potential of bileaflet valves in vivo. The post processing of HFPF have shown difficulties when applied on bileaflet vavles due to asynchronous closure of the two leaflets. The aim of this study was therefore to isolate the pressure signature from each leaflet closure and perform cavitation analyses on each component. Six patients were included in the study (St. Jude Medical (n=3) and CarboMedics (n=3); all aortic bileaflet mechanical heart valves). HFPFs were recorded intraoperatively through a hydrophone at the aortic root. The pressure signature relating to the first and second leaflet closure was isolated and cavitation parameters were calculated (RMS after 50 kHz highpass filtering and signal energy). Data were averaged over 30 heart cycles. For all patients both the RMS value and signal energy of the second leaflet closure were higher than for the first leaflet closure. This indicates that the second leaflet closure is most prone to cause cavitation. Therefore, quantifying cavitation based on the HFPF related to the second leaflet closure may suggest that the cavitation potential for bileaflet valves in vivo may be higher than previous studies have suggested.

  16. Large Scale Magnetostrictive Valve Actuator

    NASA Technical Reports Server (NTRS)

    Richard, James A.; Holleman, Elizabeth; Eddleman, David

    2008-01-01

    Marshall Space Flight Center's Valves, Actuators and Ducts Design and Development Branch developed a large scale magnetostrictive valve actuator. The potential advantages of this technology are faster, more efficient valve actuators that consume less power and provide precise position control and deliver higher flow rates than conventional solenoid valves. Magnetostrictive materials change dimensions when a magnetic field is applied; this property is referred to as magnetostriction. Magnetostriction is caused by the alignment of the magnetic domains in the material s crystalline structure and the applied magnetic field lines. Typically, the material changes shape by elongating in the axial direction and constricting in the radial direction, resulting in no net change in volume. All hardware and testing is complete. This paper will discuss: the potential applications of the technology; overview of the as built actuator design; discuss problems that were uncovered during the development testing; review test data and evaluate weaknesses of the design; and discuss areas for improvement for future work. This actuator holds promises of a low power, high load, proportionally controlled actuator for valves requiring 440 to 1500 newtons load.

  17. Valve packings conquer fugitive emissions

    SciTech Connect

    1995-11-01

    In the early 1990s, when the US Environmental Protection Agency (EPA; Washington, D.C.) declared its intent to regulate fugitive emissions from valve-stem leakage, much of the chemical process industries (CPI) responded with fear and uncertainty. The biggest fear was that valve packing would not meet the required limits on leak rates and that expensive bellows seals may be required on many applications. The uncertainly was about how much it would cost. Today, for the most part, these concerns have been mitigated. It is estimated that about 80--90% of valves satisfy the emission requirements. The rest need some improvement in their packing systems to meet the regulations. Generally, these valves can be brought within compliance if the packing designers follow a few basic principles: Employ less-pliable outer rings and more-pliable inner rings; and don`t use excessive packing. While interest in valve packing remains high, mechanical seals continue to become more user-friendly. Many of those covered below are designed to run dry, and some can even tolerate high shaft-wobble without damage. Also look for improved flange gaskets and a host of seals to protect bearings. Twenty-one summaries are presented on new products and services.

  18. Titanium in Engine Valve Systems

    NASA Astrophysics Data System (ADS)

    Allison, J. E.; Sherman, A. M.; Bapna, M. R.

    1987-03-01

    Titanium alloys offer a unique combination of high strength-to-weight ratio, good corrosion resistance and favorable high temperature mechanical properties. Still, their relatively high cost has discouraged consideration for widespread use in automotive components. Recent demands for increased fuel economy have led to the consideration of these alloys for use as valve train materials where higher costs might be offset by improvements in performance and fuel economy. Lighter weight valve train components permit the use of lower spring loads, thus reducing friction and increasing fuel economy. Camshaft friction measurements made on a typical small displacement engine indicate that a twoto-four percent increase in fuel economy can be achieved. Valve train components are, however, subject to a severe operating environment, including elevated temperatures, sliding wear and high mechanical loads. This paper discusses the details of alloy and heat treatment selection for optimizing valve performance. When properly manufactured, titanium valves have been shown to withstand very stringent durability testing, indicating the technical feasibility of this approach to fuel economy improvement.

  19. Mitral annular calcification in patients undergoing aortic valve replacement for aortic valve stenosis.

    PubMed

    Takami, Yoshiyuki; Tajima, Kazuyoshi

    2016-02-01

    Limited data exis t on clinical relevance of aortic valve stenosis (AVS) and mitral annular calcification (MAC), although with similar pathophysiologic basis. We sought to reveal the prevalence of MAC and its clinical features in the patients undergoing aortic valve replacement (AVR) for AVS. We reviewed 106 consecutive patients who underwent isolated AVR from 2004 to 2010. Before AVR, CT scans were performed to identify MAC, whose severity was graded on a scale of 0-4, with grade 0 denoting no MAC and grade 4 indicating severe MAC. Echocardiography was performed before AVR and at follow-up over 2 years after AVR. MAC was identified in 56 patients with grade 1 (30 %), 2 (39 %), 3 (18 %), and 4 (13 %), respectively. Patients with MAC presented older age (72 ± 8 versus 66 ± 11 years), higher rate of dialysis-dependent renal failure (43 versus 4 %), and less frequency of bicuspid aortic valve (9 versus 36 %), when compared to those without MAC. No significant differences were seen in short- and mid-term mortality after AVR between the groups. In patients with MAC, progression of neither mitral regurgitation nor stenosis was observed at follow-up of 53 ± 23 months for 102 survivors, although the transmitral flow velocities were higher than in those without MAC. In conclusion, MAC represented 53 % of the patients undergoing isolated AVR for AVS, usually appeared in dialysis-dependent elder patients with tricuspid AVS. MAC does not affect adversely upon the survival, without progression of mitral valve disease, at least within 2 years after AVR.

  20. Half-metallic superconducting triplet spin valve

    NASA Astrophysics Data System (ADS)

    Halterman, Klaus; Alidoust, Mohammad

    2016-08-01

    We theoretically study a finite-size S F1N F2 spin valve, where a normal metal (N ) insert separates a thin standard ferromagnet (F1) and a thick half-metallic ferromagnet (F2). For sufficiently thin superconductor (S ) widths close to the coherence length ξ0, we find that changes to the relative magnetization orientations in the ferromagnets can result in substantial variations in the transition temperature Tc, consistent with experimental results [Singh et al., Phys. Rev. X 5, 021019 (2015), 10.1103/PhysRevX.5.021019]. Our results demonstrate that, in good agreement with the experiment, the variations are largest in the case where F2 is in a half-metallic phase and thus supports only one spin direction. To pinpoint the origins of this strong spin-valve effect, both the equal-spin f1 and opposite-spin f0 triplet correlations are calculated using a self-consistent microscopic technique. We find that when the magnetization in F1 is tilted slightly out of plane, the f1 component can be the dominant triplet component in the superconductor. The coupling between the two ferromagnets is discussed in terms of the underlying spin currents present in the system. We go further and show that the zero-energy peaks of the local density of states probed on the S side of the valve can be another signature of the presence of superconducting triplet correlations. Our findings reveal that for sufficiently thin S layers, the zero-energy peak at the S side can be larger than its counterpart in the F2 side.

  1. A magnetically driven PDMS micropump with ball check-valves

    NASA Astrophysics Data System (ADS)

    Pan, Tingrui; McDonald, Scott J.; Kai, Eleanor M.; Ziaie, Babak

    2005-05-01

    In this paper, we present a low-cost, PDMS-membrane micropump with two one-way ball check-valves for lab-on-a-chip and microfluidic applications. The micropump consists of two functional PDMS layers, one holding the ball check-valves and an actuating chamber, and the other covering the chamber and holding a miniature permanent magnet on top for actuation. An additional PDMS layer is used to cover the top magnet, and thereby encapsulate the entire device. A simple approach was used to assemble a high-performance ball check-valve using a micropipette and heat shrink tubing. The micropump can be driven by an external magnetic force provided by another permanent magnet or an integrated coil. In the first driving scheme, a small dc motor (6 mm in diameter and 15 mm in length) with a neodymium-iron-boron permanent magnet embedded in its shaft was used to actuate the membrane-mounted magnet. This driving method yielded a large pumping rate with very low power consumption. A maximum pumping rate of 774 µL min-1 for deionized water was achieved at the input power of 13 mW, the highest pumping rate reported in the literature for micropumps at such power consumptions. Alternatively, we actuated the micropump with a 10-turn planar coil fabricated on a PC board. This method resulted in a higher pumping rate of 1 mL min-1 for deionized water. Although more integratable and compact, the planar microcoil driving technique has a much higher power consumption.

  2. Pulmonary Valve Replacement With a Trifecta Valve Is Associated With Reduced Transvalvular Gradient

    PubMed Central

    Gulack, Brian C.; Benrashid, Ehsan; Jaquiss, Robert D. B.; Lodge, Andrew J.

    2016-01-01

    Background Outcomes after surgical pulmonary valve replacement (PVR) in patients with congenital cardiac disease are limited by long-term valve deterioration, which may be hastened by turbulent flow. The use of the Trifecta valve (St. Jude Medical, Little Canada, MN) at our institution (Duke University Medical Center, Durham, NC) appears to result in low postimplantation transvalvular gradients. This study was performed to compare the early transvalvular gradient associated with the Trifecta valve with that associated with two other valves commonly used for PVR. Methods We performed a single institution review of patients undergoing PVR with the Perimount valve (Edwards Lifesciences, Irvine, CA), the Biocor valve (St. Jude Medical), or the Trifecta valve between November 1993 and January 2014. Multivariable linear regression modeling was used to determine the adjusted association between valve type and transvalvular gradient as determined by early postoperative echocardiography. Results A total of 186 patients met study criteria; 54 (29%) received a Biocor valve, 87 (47%) received a Perimount valve, and 45 (24%) received a Trifecta valve. There were no baseline differences among the groups, but the peak transvalvular gradient was significantly decreased among patients with the Trifecta valve. After adjustment for age, valve size, patients’ weight, and time to the assessment, as compared with the Trifecta valve, the Biocor valve was associated with a 57% higher peak valve gradient (p < 0.01), whereas the Perimount valve was associated with a 26% higher peak valve gradient (p = 0.04). Conclusions PVR for congenital heart disease with the Trifecta bioprosthetic valve is associated with a reduced early transvalvular gradient. This finding may be associated with reduced valve deterioration over time. PMID:27570156

  3. 5. DIABLO DAM: DETAIL VIEW OF RELIEF VALVES AT ELEVATION ...

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

    5. DIABLO DAM: DETAIL VIEW OF RELIEF VALVES AT ELEVATION 1044. VALVE IN FOREGROUND IS A BUTTERFLY VALVE SIX FEET IN DIAMETER; VALVE TO THE REAR IS A JOHNSON-TYPE NEEDLE VALVE BOTH VALVES WERE MANUFACTURED BY THE PELTON WATER WHEEL COMPANY, 1989. - Skagit Power Development, Diablo Dam, On Skagit River, 6.9 miles upstream from Newhalem, Newhalem, Whatcom County, WA

  4. Coolant-Control Valves For Fluid-Sampling Probes

    NASA Technical Reports Server (NTRS)

    Schultz, Donald F.

    1989-01-01

    Small built-in leaks prevent overheating. Downstream flow-control globe valve replaced with modified gate valve. Modification consists of drilling small hole through valve gate, so valve never turned completely off. This "leaky" valve provides enough flow of coolant to prevent overheating causing probe to fail. Principle also applied to automatic control system by installing small bypass line around control valve.

  5. 46 CFR 56.20-15 - Valves employing resilient material.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Category B, and shall be tested and used as follows: (1) Positive shutoff valves. The closed valve must... Category A or Category B valve. (2) Category A valves. The closed valve must pass less than the greater of...) from functioning as designed. (iii) Valves providing closure for any opening in the shell of the...

  6. Improved technique of transapical aortic valve implantation: "the Berlin addition".

    PubMed

    Pasic, Miralem; Dreysse, Stephan; Drews, Thorsten; Buz, Semih; Unbehaun, Axel; Kukucka, Marian; Mladenow, Alexandar; Hetzer, Roland

    2010-06-01

    Transapical aortic valve implantation carries some degree of uncertainty regarding the definitive valve position. We added angiographic visualization of the aortic root while the prosthetic valve is being slowly deployed. It enables easy correction of the position of the valve so that perfect alignment can be achieved of the relationships between the prosthetic valve, aortic valve annulus, aortic cusps, and the coronary arteries.

  7. How Is Heart Valve Disease Diagnosed?

    MedlinePlus

    ... page from the NHLBI on Twitter. How Is Heart Valve Disease Diagnosed? Your primary care doctor may detect a heart murmur or other signs of heart valve disease. However, a cardiologist usually will diagnose the condition. ...

  8. SLM Produced Hermetically Sealed Isolation Valve

    NASA Technical Reports Server (NTRS)

    Richard, James

    2014-01-01

    Marshall Space Flight Center (MSFC) has developed a valve concept to replace traditional pyrotechnic-driven isolation valves. This paper will describe the valve design and development process. The valve design uses a stem/wedge to support a disk inside the valve. That disk hermetically seals the pressurized fluids. A release mechanism holds the stem/wedge and a large spring in place. When required to open, a solenoid is energized and pulls the release mechanism allowing the spring to pull the stem/wedge away from the disk. Now the disk is unsupported and the pressure ruptures the disk allowing flow to the outlet of the valve. This paper will provide details of this design, describe the development testing, and show the results from the valve level tests performed. Also, a trade study is presented to show the advantages of this design to a conventional pyrotechnic-based valve.

  9. SLM Produced Hermetically Sealed Isolation Valve

    NASA Technical Reports Server (NTRS)

    Richard, James A.

    2014-01-01

    Marshall Space Flight Center (MSFC) has developed a valve concept to replace traditional pyrotechnic driven isolation valves. This paper will describe the valve design and development process. The valve design uses a stem/wedge to support a disk inside the valve. That disk hermetically seals the pressurized fluids. A release mechanism holds the stem/wedge and a large spring in place. When required to open, a solenoid is energized and pulls the release mechanism allowing the spring to pull the stem/wedge away from the disk. Now the disk is unsupported and the pressure ruptures the disk allowing flow to the outlet of the valve. This paper will provide details of this design, describe the development testing, and show the results from the valve level tests performed. Also, a trade study is presented to show the advantages of this design to a conventional pyrotechnic based valve.

  10. Abrasion and resistant discharge valve developed

    NASA Technical Reports Server (NTRS)

    Gottwald, W. L.

    1969-01-01

    Discharge valve capable of withstanding intense radiation and high abrasion was developed for use in a fluidized bed reactor. The valve which employs a replaceable Teflon seal, has only one moving part and is designed for remote assembly and disassembly.

  11. Design criteria monograph for valve assemblies

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Monograph is limited to valve selection factors for trade-off studies, configuration analyses, actuator selection, and integration of components. Material is organized along lines of valve design sequence.

  12. Geometry of aortic heart valves. [prosthetic design

    NASA Technical Reports Server (NTRS)

    Karara, H. M.

    1975-01-01

    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.

  13. Intro to Valve Guide Reconditioning. Automotive Mechanics. Valves. Instructor's Guide [and] Student Guide.

    ERIC Educational Resources Information Center

    Horner, W.

    This instructional package, one in a series of individualized instructional units on tools and techniques for repairing worn valve guides in motor vehicles, provides practical experience for students in working on cylinder heads. Covered in the module are reaming valve guides that are oversized to match a new oversized valve, reaming valve guides…

  14. Aortic valve replacement with the Nicks annulus enlargement procedure 12 years after mitral valve replacement.

    PubMed

    Kazama, S; Kurata, A; Yamashita, Y

    1999-10-01

    An aortic valve replacement was successfully performed employing the Nicks annulus enlargement procedure in a case of aortic valve stenosis with small annulus 12 years after mitral valve replacement. Previous mitral valve replacement does not preclude feasibility of the Nicks procedure.

  15. Propellant isolation shutoff valve program

    NASA Technical Reports Server (NTRS)

    Merritt, F. L.

    1973-01-01

    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.

  16. Bistable diverter valve in microfluidics

    NASA Astrophysics Data System (ADS)

    Tesař, V.; Bandalusena, H. C. H.

    2011-05-01

    Bistable diverter valves are useful for a large number of no-moving-part flow control applications, and there is a considerable interest in using them also in microfluidics, especially for handling small pressure-driven flows. However, with decreasing Reynolds number, the Coanda effect—on which the flow diverting effect depends—becomes less effective. Authors performed a study, involving flow visualisation, PIV experiments, measurements of the flow rates, and numerical flowfield computations, aimed at clarifying behaviour of a typical fluidic valve at low Reynolds numbers. A typical fluidic valve originally developed for high Re operation was demonstrated to be useful, though with progressively limited efficiency, down to surprisingly low Re values as small as Re = 800. Also observed was a previously not reported discontinuation in the otherwise monotonic decrease in performance at Re between 1,500 and 2,000.

  17. Novel Active Combustion Control Valve

    NASA Technical Reports Server (NTRS)

    Caspermeyer, Matt

    2014-01-01

    This project presents an innovative solution for active combustion control. Relative to the state of the art, this concept provides frequency modulation (greater than 1,000 Hz) in combination with high-amplitude modulation (in excess of 30 percent flow) and can be adapted to a large range of fuel injector sizes. Existing valves often have low flow modulation strength. To achieve higher flow modulation requires excessively large valves or too much electrical power to be practical. This active combustion control valve (ACCV) has high-frequency and -amplitude modulation, consumes low electrical power, is closely coupled with the fuel injector for modulation strength, and is practical in size and weight. By mitigating combustion instabilities at higher frequencies than have been previously achieved (approximately 1,000 Hz), this new technology enables gas turbines to run at operating points that produce lower emissions and higher performance.

  18. Non-collinear valve actuator

    NASA Technical Reports Server (NTRS)

    Richard, James A. (Inventor)

    2012-01-01

    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.

  19. Active combustion flow modulation valve

    DOEpatents

    Hensel, John Peter; Black, Nathaniel; Thorton, Jimmy Dean; Vipperman, Jeffrey Stuart; Lambeth, David N; Clark, William W

    2013-09-24

    A flow modulation valve has a slidably translating hollow armature with at least one energizable coil wound around and fixably attached to the hollow armature. The energizable coil or coils are influenced by at least one permanent magnet surrounding the hollow armature and supported by an outer casing. Lorentz forces on the energizable coils which are translated to the hollow armature, increase or decrease the flow area to provide flow throttling action. The extent of hollow armature translation depends on the value of current supplied and the direction of translation depends on the direction of current flow. The compact nature of the flow modulation valve combined with the high forces afforded by the actuator design provide a flow modulation valve which is highly responsive to high-rate input control signals.

  20. Towards Performance Prognostics of a Launch Valve

    DTIC Science & Technology

    2014-10-02

    works are related to this paper’s efforts. Gomes et. al. developed a health monitoring system for a pneumatic valve using a Probability Integral...Transform based technique (Gomes 2010) and Daigle et. al. developed a model-based prognostics approach for pneumatic valves (Daigle 2011). While the...Launch Valve in this work is hydraulically controlled, the methods used for pneumatic valve PHM are quite relevant. Diagle et. al. used a Probability