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Sample records for cycle-to-cycle pressure variations

  1. Preliminary investigation of cycle-to-cycle variations in a nonair-breathing diesel engine

    SciTech Connect

    Zheng, M.; Reader, G.T.

    1995-03-01

    The effect of nonair mixtures on cycle-to-cycle variations of cylinder pressure characteristics was investigated experimentally with an indirect-injected (IDI) diesel engine. The engine intake temperature and pressure were maintained at normal air-breathing conditions when operated with nonair mixtures. Preliminary results indicate that increases in carbon dioxide concentration can cause significant cyclic variations. Moreover, the extent of such cyclic variations is notably influenced by the oxygen concentration and inert gas constitutents of the working fluids.

  2. Modelling cycle to cycle variations in an SI engine with detailed chemical kinetics

    SciTech Connect

    Etheridge, Jonathan; Mosbach, Sebastian; Kraft, Markus; Wu, Hao; Collings, Nick

    2011-01-15

    This paper presents experimental results and a new computational model that investigate cycle to cycle variations (CCV) in a spark ignition (SI) engine. An established stochastic reactor model (SRM) previously used to examine homogeneous charge compression ignition (HCCI) combustion has been extended by spark initiation, flame propagation and flame termination sub-models in order to simulate combustion in SI engines. The model contains a detailed chemical mechanism but relatively short computation times are achieved. The flame front is assumed to be spherical and centred at the spark location, and a pent roof and piston bowl geometry are accounted for. The model is validated by simulating the pressure profile and emissions from an iso-octane fuelled single cylinder research engine that showed low CCV. The effects of key parameters are investigated. Experimental results that show cycle to cycle fluctuations in a four-cylinder naturally aspirated gasoline fuelled SI engine are presented. The model is then coupled with GT-Power, a one-dimensional engine simulation tool, which is used to simulate the breathing events during a multi-cycle simulation. This allows an investigation of the cyclic fluctuations in peak pressure. The source and magnitude of nitric oxide (NO) emissions produced by different cycles are then investigated. It was found that faster burning cycles result in increased NO emissions compared with cycles that have a slower rate of combustion and that more is produced in the early stages of combustion compared with later in the cycle. The majority of NO was produced via the thermal mechanism just after combustion begins. (author)

  3. Characteristic of blended fuel properties and engine cycle-to-cycle variations with butanol additive

    NASA Astrophysics Data System (ADS)

    Ali, Obed M.; Mamat, Rizalman; Abdullah, Nik R.; Abdullah, Abdul Adam

    2015-05-01

    Biodiesel fuel characteristics are one of the most important parameters that limited their application in diesel engines. Though biodiesel-diesel blended fuel can replace diesel satisfactorily at low blending ratios up to 20%, problems related to fuel property persist at high blending ratio. Hence, in the present study, the feasibility of biodiesel-diesel blended fuel B30 was investigated with respect to its properties and engine cyclic variations with increasing butanol additive. The blended fuel with additive were tested experimentally in a diesel engine and the in-cylinder pressure data were collected and analyzed using the coefficient of variation and wavelet power spectrum to evaluate the engine cyclic variations compared to diesel fuel engine test results. The fuel property test results showed slight improvement in density and acid value with significant reduction in viscosity when increasing butanol additive. Furthermore, the blended fuel pour point was reduced to -6 °C at 8% butanol additive. On the other hand, the energy content slightly affected with increasing butanol additive in the blend. From the wavelet power spectrum, it is observed that the short-period oscillations appear intermittently in pure blended fuel, while the long and intermediate-term periodicities tends to appear with increasing additive ratio. Moreover, the spectral power increased with an increase in the additive ratio indicating that the additive has a noticeable effect on increasing the cycle to cycle variation. The coefficient of variation of indicated mean effective pressure for B30 were found to be the lowest and increases with increasing additive ratios. Both the wavelet analysis and coefficient of variation results reveals that blended fuel B30 has engine cyclic variations comparable to diesel fuel with increasing butanol additive up to 4%.

  4. Cluster-based analysis of cycle-to-cycle variations: application to internal combustion engines

    NASA Astrophysics Data System (ADS)

    Cao, Yujun; Kaiser, Eurika; Borée, Jacques; Noack, Bernd R.; Thomas, Lionel; Guilain, Stéphane

    2014-11-01

    We define and illustrate a cluster-based analysis of cycle-to-cycle variations (CCV). The methodology is applied to engine flow but can clearly be valuable for any periodically driven fluid flow at large Reynolds numbers. High-speed particle image velocimetry data acquired during the compression stroke for 161 consecutive engine cycles are used. Clustering is applied to the velocity fields normalised by their kinetic energy. From a phase-averaged analysis of the statistics of cluster content and inter- cluster transitions, we show that CCV can be associated with different sets of trajectories during the second half of the compression phase. Conditional statistics are computed for flow data of each cluster. In particular, we identify a particular subset associated with a loss of large-scale coherence, a very low kinetic energy of the mean flow and a higher fluctuating kinetic energy. This is interpreted as a good indicator of the breakdown of the large-scale coherent tumbling motion. For this particular subset, the cluster analysis confirms the idea of a gradual destabilisation of the in-cylinder flow during the final phase of the compression. Moreover, inter- cycle statistics show that the flow states near TDC and in the measurement zone are statistically independent for consecutive engine cycles. It is important to point out that this approach is generally applicable to very large sets of data, e.g. generated by PIV or LES, and independent of the considered type of information (velocity, concentration, etc.).

  5. Investigating Cepheid ℓ Carinae's cycle-to-cycle variations via contemporaneous velocimetry and interferometry★

    NASA Astrophysics Data System (ADS)

    Anderson, R. I.; Mérand, A.; Kervella, P.; Breitfelder, J.; LeBouquin, J.-B.; Eyer, L.; Gallenne, A.; Palaversa, L.; Semaan, T.; Saesen, S.; Mowlavi, N.

    2016-02-01

    Baade-Wesselink-type (BW) techniques enable geometric distance measurements of Cepheid variable stars in the Galaxy and the Magellanic clouds. The leading uncertainties involved concern projection factors required to translate observed radial velocities (RVs) to pulsational velocities and recently discovered modulated variability. We carried out an unprecedented observational campaign involving long-baseline interferometry (VLTI/PIONIER) and spectroscopy (Euler/Coralie) to search for modulated variability in the long-period (P ˜ 35.5 d) Cepheid ℓ Carinae. We determine highly precise angular diameters from squared visibilities and investigate possible differences between two consecutive maximal diameters, ΔmaxΘ. We characterize the modulated variability along the line of sight using 360 high-precision RVs. Here we report tentative evidence for modulated angular variability and confirm cycle-to-cycle differences of ℓ Carinae's RV variability. Two successive maxima yield ΔmaxΘ = 13.1 ± 0.7(stat.) μas for uniform disc models and 22.5 ± 1.4(stat.) μas (4 per cent of the total angular variation) for limb-darkened models. By comparing new RVs with 2014 RVs, we show modulation to vary in strength. Barring confirmation, our results suggest the optical continuum (traced by interferometry) to be differently affected by modulation than gas motions (traced by spectroscopy). This implies a previously unknown time dependence of projection factors, which can vary by 5 per cent between consecutive cycles of expansion and contraction. Additional interferometric data are required to confirm modulated angular diameter variations. By understanding the origin of modulated variability and monitoring its long-term behaviour, we aim to improve the accuracy of BW distances and further the understanding of stellar pulsations.

  6. Cycle-to-Cycle Variations in the Diurnal Variation of Galactic Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Thomas, Simon; Owen, Chris; Owens, Matt; Lockwood, Mike

    2016-04-01

    We examine mean profiles of the diurnal variations in galactic cosmic ray flux using a number of neutron monitors at different magnetic latitudes and longitudes. By splitting all of the hourly neutron monitor data by the solar magnetic polarity and analysing the mean normalised neutron monitor count rates between these, we see that the diurnal variation changes phase by 1-2 hours between the two polarity states for the majority of non-polar neutron monitors. The intensity and variability of a heliospheric magnetic field is analysed for every day and found not to be the cause of the phase change. Some polar neutron monitors, however, show different, smaller amplitude variations in phase between polarity cycles. Time series of the time of the maximum in the diurnal variation are presented between 1965 and 2013. Our results agree with previous work by confirming the presence of a 22-year variation in the peak time of the diurnal variation and a 11-year variation in the amplitude, but also show that not all neutron monitors show the same trend. An analysis of the magnetic latitude dependence of the diurnal variation shows that the time-of-day of the peak and trough of this variation gives opposing changes to the amplitude of the 22-year change. We suggest that this could be due to changes in the configeration of the heliospheric magnetic field for consecutive cycles.

  7. Application of High Performance Computing for Simulating Cycle-to-Cycle Variation in Dual-Fuel Combustion Engines

    DOE PAGESBeta

    Jupudi, Ravichandra S.; Finney, Charles E.A.; Primus, Roy; Wijeyakulasuriya, Sameera; Klingbeil, Adam E.; Tamma, Bhaskar; Stoyanov, Miroslav K.

    2016-04-05

    Interest in operational cost reduction is driving engine manufacturers to consider lower-cost fuel substitution in heavy-duty diesel engines. These dual-fuel (DF) engines could be operated either in diesel-only mode or operated with premixed natural gas (NG) ignited by a pilot flame of compression-ignited direct-injected diesel fuel. One promising application is that of large-bore, medium-speed engines such as those used in locomotives. With realistic natural gas substitution levels in the fleet of locomotives currently in service, such fuel substitution could result in billions of dollars of savings annually in the US alone. However, under certain conditions, dual-fuel operation can result inmore » increased cycle-to-cycle variability (CCV) during combustion, resulting in variations in cylinder pressure and work extraction. In certain situations, the CCV of dual-fuel operation can be notably higher than that of diesel-only combustion under similar operating conditions. Excessive CCV can limit the NG substitution rate and operating range of a dual-fuel engine by increasing emissions and reducing engine stability, reliability and fuel efficiency via incomplete natural-gas combustion. Running multiple engine cycles in series to simulate CCV can be quite time consuming. Hence innovative modelling techniques and large computing resources are needed to investigate the factors affecting CCV in dual-fuel engines. This paper discusses the use of the High Performance Computing resource Titan, at the Oak Ridge Leadership Computing Facility at Oak Ridge National Laboratory, to investigate cycle-to-cycle combustion variability of a dual-fuel engine. The CONVERGE CFD software was used to simulate multiple, parallel single cycles of dual-fuel combustion with perturbed operating parameters and boundary conditions. These perturbations are imposed according to a sparse grids sampling of the parameter space. The sampling scheme chosen is similar to a design of experiments method

  8. Proper orthogonal decomposition analysis for cycle-to-cycle variations of engine flow. Effect of a control device in an inlet pipe

    NASA Astrophysics Data System (ADS)

    Vu, Trung-Thanh; Guibert, Philippe

    2012-06-01

    This paper aims to investigate cycle-to-cycle variations of non-reacting flow inside a motored single-cylinder transparent engine in order to judge the insertion amplitude of a control device able to displace linearly inside the inlet pipe. Three positions corresponding to three insertion amplitudes are implemented to modify the main aerodynamic properties from one cycle to the next. Numerous particle image velocimetry (PIV) two-dimensional velocity fields following cycle database are post-treated to discriminate specific contributions of the fluctuating flow. We performed a multiple snapshot proper orthogonal decomposition (POD) in the tumble plane of a pent roof SI engine. The analytical process consists of a triple decomposition for each instantaneous velocity field into three distinctive parts named mean part, coherent part and turbulent part. The 3rd- and 4th-centered statistical moments of the proper orthogonal decomposition (POD)-filtered velocity field as well as the probability density function of the PIV realizations proved that the POD extracts different behaviors of the flow. Especially, the cyclic variability is assumed to be contained essentially in the coherent part. Thus, the cycle-to-cycle variations of the engine flows might be provided from the corresponding POD temporal coefficients. It has been shown that the in-cylinder aerodynamic dispersions can be adapted and monitored by controlling the insertion depth of the control instrument inside the inlet pipe.

  9. Barometric pressure variations

    SciTech Connect

    Crippen, M.D.

    1993-06-01

    This report presents Hanford Site barometric data that can be used to determine the breathing rate of Hanford Site tanks and details the derivation of the data. The barometric pressure data recorded at the Hanford Weather Station were used for this analysis. Data for 1988, 1989, 1990, and 1991 were used.

  10. Discovery of Cycle-to-cycle Modulated Spectral Line Variability and Velocity Gradients in Long-period Cepheids

    NASA Astrophysics Data System (ADS)

    Anderson, Richard I.

    2016-08-01

    This work reports the discovery of cycle-to-cycle modulated spectral line and atmospheric velocity gradient variability in long-period Cepheids based on 925 high-resolution optical spectra of ℓ Carinae (P ˜ 35.5 d) recorded during three heavy duty-cycle monitoring campaigns (in 2014, 2015, and 2016). Spectral line variability is investigated via cross-correlation functions (CCFs) computed using three sets of spectral lines (weak, solar, strong). A metallic line velocity gradient, δvr(t), is computed as the difference between weak and strong-line RVs. CCF shape indicators BIS (asymmetry), FWHM, and depth all exhibit clear phase-dependent variability patterns that differ from one pulsation cycle to the next. Weak-line CCFs exhibit these effects more clearly than strong-line CCFs. BIS exhibits the most peculiar modulated variability and can be used to identify the presence of cycle-to-cycle modulated line profile variations. δvr(t) clearly exhibits cycle-to-cycle differences that correlate very closely with modulated BIS variability, suggesting perturbations of the atmospheric velocity field as the cause for modulated spectral line variability. These perturbations are most significant during contraction and are not in phase with the pulsation, transmitting information between consecutive pulsation cycles. This work shows RV curve modulation to be a consequence of atmospheric velocity gradient perturbations. Possible origins of these perturbations and their impact on Cepheid RV measurements as well as the projection factor used in Baade-Wesselink-type distance determinations are discussed.

  11. Experimental implementation of automatic 'cycle to cycle' control of a chiral simulated moving bed separation.

    PubMed

    Amanullah, Mohammad; Grossmann, Cristian; Mazzotti, Marco; Morari, Manfred; Morbidelli, Massimo

    2007-09-21

    In the absence of a suitable controller, currently simulated moving beds (SMBs) are operated suboptimally to cope with system uncertainties and to guarantee robustness of operation. Recently, we have developed a 'cycle to cycle' optimizing controller that not only makes use of minimal system information, i.e. only the Henry constants and average bed voidage, but also optimizes the process performance and taps the full economic potential of the SMB technology. The experimental implementation of the 'cycle to cycle' optimizing controller had been carried out for achiral separation. For chiral separation however, application of any online controller has not been possible because an appropriate online monitoring system has not been available. This work reports and discusses the first experimental implementation of the 'cycle to cycle' optimizing control for chiral separations. A mixture of guaifenesin enantiomers is separated on Chiralcel OD columns with ethanol as mobile phase in a eight-column four sections laboratory SMB unit. The results show that the controller, although using minimal information about the retention of the two enantiomers, is able to meet product and process specifications, can optimize the process performance, and is capable of rejecting disturbances that may occur during the operation of the SMB plant. PMID:17707852

  12. Quantifying pressure variations from petrographic observations

    NASA Astrophysics Data System (ADS)

    Vrijmoed, Johannes C.; Podladchikov, Yuri Y.

    2015-04-01

    The existence of grain scale pressure variations has been established over the last decennia. Mineral reactions are often accompanied by volume and shape changes in a system where much heterogeneity in material properties exists. This gives rise to internal stresses and pressure variation during metamorphic reactions. The residual pressure in inclusions can be measured by Raman spectroscopy, but is restricted to a narrow range of minerals that (potentially) have a well calibrated Raman shift with pressure. Several alternative methods to quantify pressure variations from petrographic observations are presented. We distinguish equilibrium and non-equilibrium methods. Equilibrium methods are based on a newly developed method to predict phase equilibria and composition under a given pressure gradient. The pressure gradient can be found by iteratively matching predicted phase assemblages and composition with petrographic observations. Non-equilibrium methods involve the estimation of pressure variation in initial stages of reaction in which the system may still be isochoric. It then results in the potential pressure buildup for a given unreacted rock for example in the initial stages of dehydration of serpentinite in subduction settings.

  13. Intradiscal pressure variation under spontaneous ventilation

    NASA Astrophysics Data System (ADS)

    Roriz, Paulo; Ferreira, J.; Potes, J. C.; Oliveira, M. T.; Santos, J. L.; Simões, J. A.; Frazão, O.

    2014-05-01

    The pressure measured in the intervertebral discs is a response to the loads acting on the spine. External loads, such as the reaction forces resulting from locomotion, manual handling and collisions are probably the most relevant in studying spine trauma. However, the physiological functions such as breathing and hearth rate also participate in subtle variations of intradiscal pressure that can be observed only in vivo at resting. Present work is an effort to measure the effect of breathing on intradiscal pressure of an anesthetized sheep.

  14. Neighborhood Disadvantage and Variations in Blood Pressure

    ERIC Educational Resources Information Center

    Cathorall, Michelle L.; Xin, Huaibo; Peachey, Andrew; Bibeau, Daniel L.; Schulz, Mark; Aronson, Robert

    2015-01-01

    Purpose: To examine the extent to which neighborhood disadvantage accounts for variation in blood pressure. Methods: Demographic, biometric, and self-reported data from 19,261 health screenings were used. Addresses of participants were geocoded and located within census block groups (n = 14,510, 75.3%). Three hierarchical linear models were…

  15. Cycle-to-cycle extraction synchronization of the Fermilab Booster for multiple batch injection to the Main Injector

    SciTech Connect

    Zwaska, R.; Kopp, S.; Pellico, W.; /Fermilab

    2005-05-01

    We report on a system to ensure cycle-to-cycle synchronization of beam extraction from the Fermilab Booster accelerator to the Main Injector. Such synchronization is necessary for multiple batch operation of the Main Injector for the Run II upgrade of anti-proton production using slip-stacking in the Main Injector, and for the NuMI (Neutrinos at the Main Injector) neutrino beam. To perform this task a system of fast measurements and feedback controls the longitudinal progress of the Booster beam throughout its acceleration period by manipulation of the transverse position maintained by the LLRF (Low-level Radio Frequency) system.

  16. 49 CFR 195.104 - Variations in pressure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Variations in pressure. 195.104 Section 195.104... PIPELINE Design Requirements § 195.104 Variations in pressure. If, within a pipeline system, two or more components are to be connected at a place where one will operate at a higher pressure than another,...

  17. 49 CFR 195.104 - Variations in pressure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Variations in pressure. 195.104 Section 195.104... PIPELINE Design Requirements § 195.104 Variations in pressure. If, within a pipeline system, two or more components are to be connected at a place where one will operate at a higher pressure than another,...

  18. 49 CFR 195.104 - Variations in pressure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Variations in pressure. 195.104 Section 195.104... PIPELINE Design Requirements § 195.104 Variations in pressure. If, within a pipeline system, two or more components are to be connected at a place where one will operate at a higher pressure than another,...

  19. 49 CFR 195.104 - Variations in pressure.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Variations in pressure. 195.104 Section 195.104... PIPELINE Design Requirements § 195.104 Variations in pressure. If, within a pipeline system, two or more components are to be connected at a place where one will operate at a higher pressure than another,...

  20. Vasodilation increases pulse pressure variation, mimicking hypovolemic status in rabbits

    PubMed Central

    Westphal, Glauco A; Gonçalves, Anderson Roman; Bedin, Antônio; Steglich, Raquel Bissacotti; Silva, Eliezer; Poli-de-Figueiredo, Luiz Francisco

    2010-01-01

    OBJECTIVE To test the hypothesis that pulse pressure respiratory variation (PPV) amplification, observed in hypovolemia, can also be observed during sodium nitroprusside (SNP)-induced vasodilation. INTRODUCTION PPV is largely used for early identification of cardiac responsiveness, especially when hypovolemia is suspected. PPV results from respiratory variation in transpulmonary blood flow and reflects the left ventricular preload variations during respiratory cycles. Any factor that decreases left ventricular preload can be associated with PPV amplification, as seen in hypovolemia. METHODS Ten anesthetized and mechanically ventilated rabbits underwent progressive hypotension by either controlled hemorrhage (Group 1) or intravenous SNP infusion (Group 2). Animals in Group 1 (n = 5) had graded hemorrhage induced at 10% steps until 50% of the total volume was bled. Mean arterial pressure (MAP) steps were registered and assumed as pressure targets to be reached in Group 2. Group 2 (n = 5) was subjected to a progressive SNP infusion to reach similar pressure targets as those defined in Group 1. Heart rate (HR), systolic pressure variation (SPV) and PPV were measured at each MAP step, and the values were compared between the groups. RESULTS SPV and PPV were similar between the experimental models in all steps (p > 0.16). SPV increased earlier in Group 2. CONCLUSION Both pharmacologic vasodilation and graded hemorrhage induced PPV amplification similar to that observed in hypovolemia, reinforcing the idea that amplified arterial pressure variation does not necessarily represent hypovolemic status but rather potential cardiovascular responsiveness to fluid infusion. PMID:20186303

  1. Variation of sodium on Mercury with solar radiation pressure

    NASA Astrophysics Data System (ADS)

    Potter, A. E.; Morgan, T. H.

    1987-09-01

    Sodiums atoms in the atmosphere of Mercury can be accelerated by solar radiation pressure, and several authors have suggested that radiation pressure could sweep sodium off the planet. As a consequence, the sodium abundance might be expected to decrease as the radiation pressure increases. The authors have measured the average sodium abundance over a range of solar radiation pressures and found that the sodium abundance does decrease with increasing radiation pressure. Possible explanations for the observed variation are (1) that radiation pressure sweeps away transient high-velocity sodium atoms generated upon meteoric material impacts, thus reducing the supply rate of sodium, or (2) that the accommodation coefficient of sodium for surface interactions is less than unity, so that radiation pressure can effectively push sodium to the dark side of the planet, where it cannot be detected by scattered sunlight.

  2. Diurnal variation of pulmonary artery pressure in chronic heart failure.

    PubMed Central

    Gibbs, J S; Cunningham, D; Shapiro, L M; Park, A; Poole-Wilson, P A; Fox, K M

    1989-01-01

    Variation in pulmonary artery pressure has important consequences for the interpretation of isolated pressure measurements in patients with chronic heart failure. To investigate the nature of diurnal variation in pulmonary artery pressure in chronic heart failure, eight angina-free men (aged 50-72 years) with treated chronic heart failure caused by ischaemic heart disease underwent continuous ambulatory pulmonary artery pressure recording by a transducer tipped catheter. The mean (1 SD) daytime pulmonary artery pressure was 29.6 (5.0) mm Hg systolic and 13.7 (5.6) mm Hg diastolic. The mean change in pressure from day to night was +5.1 (3.2) mm Hg systolic and +3.8 (1.7) mm Hg diastolic; and the mean change from standing to lying +9.3 (2.3) mm Hg systolic and +6.4 (2.1) mm Hg diastolic. In six of the eight patients there was considerable rise in pulmonary artery pressure at night, but in the two patients with the most severe symptoms there was no nocturnal rise. In patients with chronic heart failure, nocturnal pulmonary artery pressure is not determined by postural change alone. But interpretation of isolated pulmonary artery pressure measurements must take the posture of the patient into account. PMID:2757872

  3. Techniques for estimating blood pressure variation using video images.

    PubMed

    Sugita, Norihiro; Obara, Kazuma; Yoshizawa, Makoto; Abe, Makoto; Tanaka, Akira; Homma, Noriyasu

    2015-08-01

    It is important to know about a sudden blood pressure change that occurs in everyday life and may pose a danger to human health. However, monitoring the blood pressure variation in daily life is difficult because a bulky and expensive sensor is needed to measure the blood pressure continuously. In this study, a new non-contact method is proposed to estimate the blood pressure variation using video images. In this method, the pulse propagation time difference or instantaneous phase difference is calculated between two pulse waves obtained from different parts of a subject's body captured by a video camera. The forehead, left cheek, and right hand are selected as regions to obtain pulse waves. Both the pulse propagation time difference and instantaneous phase difference were calculated from the video images of 20 healthy subjects performing the Valsalva maneuver. These indices are considered to have a negative correlation with the blood pressure variation because they approximate the pulse transit time obtained from a photoplethysmograph. However, the experimental results showed that the correlation coefficients between the blood pressure and the proposed indices were approximately 0.6 for the pulse wave obtained from the right hand. This result is considered to be due to the difference in the transmission depth into the skin between the green and infrared light used as light sources for the video image and conventional photoplethysmogram, respectively. In addition, the difference in the innervation of the face and hand may be related to the results. PMID:26737225

  4. Fuzzy FES controller using cycle-to-cycle control for repetitive movement training in motor rehabilitation. Experimental tests with wireless system.

    PubMed

    Miura, Naoto; Watanabe, Takashi; Sugimoto, Satoru; Seki, Kazunori; Kanai, Hiroshi

    2011-01-01

    A prototype of wireless surface electrical stimulation system combined with the fuzzy FES controller was developed for rehabilitation training with functional electrical stimulation (FES). The developed FES system has three features for rehabilitation training: small-sized electrical stimulator for surface FES, wireless connection between controller and stimulators, and between controller and sensors, and the fuzzy FES controller based on the cycle-to-cycle control for repetitive training. The developed stimulator could generate monophasic or biphasic high voltage stimulus pulse and could output stimulation pulses continuously more than 20 hours with 4 AAA batteries. The developed system was examined with neurologically intact subjects and hemiplegic subjects in knee joint control. The maximum knee joint angle was controlled by regulating burst duration of stimulation pulses by the fuzzy controller. In the results of two experiments of knee extension angle control and knee flexion and extension angle control, the maximum angles reached their targets within small number of cycles and were controlled stably in the stimulation cycles after reaching the target. The fuzzy FES controller based on the cycle-to-cycle control worked effectively to reach the target angle and to compensate difference in muscle properties between subjects. The developed wireless surface FES system would be practical in clinical applications of repetitive execution of similar movements of the limbs for motor rehabilitation with FES. PMID:21767134

  5. Modeling of patient's blood pressure variation during ambulance transportation

    NASA Astrophysics Data System (ADS)

    Sakatani, Kenji; Ono, Takahiko; Kobayasi, Yasuhide; Hikita, Shinichi; Saito, Mitsuyuki

    2007-12-01

    In an emergency transportation by ambulance, a patient is transported in a supine position. In this position, a patient's blood pressure (BP) variation depending on an inertial force which occurs when an ambulance accelerates or decelerates. This BP variation causes a critical damage for a patent with brain disorder. In order to keep a patient stable during transportation, it is required to maintain small BP variation. To analyze the BP variation during transportation, a model of the BP variation has so far been made. But, it can estimate the BP variation only in braking. The purpose of this paper is to make a dynamical model of the BP variation which can simulate it in both braking and accelerating. First, to obtain the data to construct the model, we used a tilting bed to measure a head-to-foot acceleration and BP of fingertip. Based on this data, we build a mathematical model whose input is the head-to-foot acceleration and output is the Mean BP variation. It is a switched model which switches two models depending on the jerk. We add baroreceptor reflex to the model as a offset value.

  6. Ventilator-induced pulse pressure variation in neonates.

    PubMed

    Heskamp, Linda; Lansdorp, Benno; Hopman, Jeroen; Lemson, Joris; de Boode, Willem-Pieter

    2016-02-01

    During positive pressure ventilation, arterial pressure variations, like the pulse pressure variation (PPV), are observed in neonates. However, the frequency of the PPV does not always correspond with the respiratory rate. It is hypothesized that PPV is caused by cardiopulmonary interaction, but that this mismatch is related to the low respiratory rate/heart rate ratio. Therefore, the goal of this study is to investigate the relation between PPV and ventilation in neonates. A prospective observational cross-sectional study was carried out in a third-level neonatal intensive care unit in a university hospital. Neonates on synchronized intermittent mandatory ventilation (SIMV) or high-frequency ventilation (HFV) participated in the study. The arterial blood pressure was continuously monitored in 20 neonates on SIMV and 10 neonates on HFV. In neonates on SIMV the CO2 waveform and neonates on HFV the thorax impedance waveform were continuously monitored and defined as the respiratory signal. Correlation and coherence between the respiratory signal and pulse pressure were determined. The correlation between the respiratory signal and pulse pressure was -0.64 ± 0.18 and 0.55 ± 0.16 and coherence at the respiratory frequency was 0.95 ± 0.11 and 0.76 ± 0.4 for SIMV and HFV, respectively. The arterial pressure variations observed in neonates on SIMV or HFV are related to cardiopulmonary interaction. Despite this relation, it is not likely that PPV will reliably predict fluid responsiveness in neonates due to physiological aliasing. PMID:26908715

  7. Variation of sodium on Mercury with solar radiation pressure

    NASA Technical Reports Server (NTRS)

    Potter, A. E.; Morgan, T. H.

    1987-01-01

    It has been suggested that nonthermal Na atoms with velocities in excess of 2.1 km/sec in the Mercury atmosphere can be accelerated off the planet by solar radiation pressure; Na abundance may accordingly be expected to decrease with increasing radiation pressure. While this is confirmed by the present measurements, high resolution line profile measurements on Na emission indicate that very little, if any, of the Na is nonthermal, while the bulk is at a temperature approaching that of the planetary surface. Attention is given to explanations for the observed variation.

  8. Why the Diurnal Pressure Variation at Curiosity is so Large

    NASA Astrophysics Data System (ADS)

    Richardson, M. I.; Heavens, N. G.; Mischna, M. A.; Newman, C. E.; Wilson, R.; Team, M.

    2013-12-01

    The diurnal range of pressure observed by the Curiosity Rover Environmental Monitoring Station (REMS) is larger than that seen at any prior Martian landing site [Harri et al., JGR 2013]. Shortly after landing, the percentage diurnal variation was roughly 11%. This range compares with general circulation model (GCM) predictions at roughly 2-5 degrees resolution of 6-7%. In the GCM, the range is primarily due to the large scale thermal tides and equatorial Kelvin waves. However, the question of why the observed range was so much larger than the GCM-predicted range was the biggest early puzzle of the REMS observation campaign. A significant clue to the puzzle is provided by the fact that high resolution models (~<10 km resolution) can adequately capture the observed range, but that if these models are averaged over an area equivalent to the GCM grid cell size, they also simultaneously match the GCM-predicted ranges. The augmented range in pressure seen by REMS and also by the mesoscale models is thus a process operating on scales smaller than captured by the GCM. Indeed, the Gale Crater site is unique amongst Mars landing sites in the large degree of topographic relief on scales of ~10km. Using basic physical arguments and mesoscale modeling, we show that the augmented range of daily pressure variation measured by REMS is due to a process of hydrostatic adjustment in response to the daily cycle of air temperature. In the presence of a slope, a change in scale height (which depends only on the air temperature) demands a change in the horizontal gradient of surface pressure. Thus, during the warmer portion of the day, the pressure difference between two fixed points at different elevations along a slope will be smaller than that during the cooler portion. If the lower elevation point is held at fixed pressure, the upper point experiences a daily pressure cycle with higher pressure during the warmer daytime and lower during the cooler night. If instead, the domain

  9. On pressure measurement and seasonal pressure variations during the Phoenix mission

    NASA Astrophysics Data System (ADS)

    Taylor, Peter A.; Kahanpää, Henrik; Weng, Wensong; Akingunola, Ayodeji; Cook, Clive; Daly, Mike; Dickinson, Cameron; Harri, Ari-Matti; Hill, Darren; Hipkin, Victoria; Polkko, Jouni; Whiteway, Jim

    2010-03-01

    In situ surface pressures measured at 2 s intervals during the 150 sol Phoenix mission are presented and seasonal variations discussed. The lightweight Barocap®/Thermocap® pressure sensor system performed moderately well. However, the original data processing routine had problems because the thermal environment of the sensor was subject to more rapid variations than had been expected. Hence, the data processing routine was updated after Phoenix landed. Further evaluation and the development of a correction are needed since the temperature dependences of the Barocap sensor heads have drifted after the calibration of the sensor. The inaccuracy caused by this appears when the temperature of the unit rises above 0°C. This frequently affects data in the afternoons and precludes a full study of diurnal pressure variations at this time. Short-term fluctuations, on time scales of order 20 s are unaffected and are reported in a separate paper in this issue. Seasonal variations are not significantly affected by this problem and show general agreement with previous measurements from Mars. During the 151 sol mission the surface pressure dropped from around 860 Pa to a minimum (daily average) of 724 Pa on sol 140 (Ls 143). This local minimum occurred several sols earlier than expected based on GCM studies and Viking data. Since battery power was lost on sol 151 we are not sure if the timing of the minimum that we saw could have been advanced by a low-pressure meteorological event. On sol 95 (Ls 122), we also saw a relatively low-pressure feature. This was accompanied by a large number of vertical vortex events, characterized by short, localized (in time), low-pressure perturbations.

  10. Intraobserver variation in Doppler ultrasound assessment of pulmonary artery pressure.

    PubMed

    Subhedar, N V; Shaw, N J

    1996-07-01

    Intraobserver variation associated with the non-invasive assessment of pulmonary artery pressure (PAP), using measurement of pulmonary artery Doppler derived systolic time intervals, was investigated. Forty pairs of independent ultrasound examinations of the pulmonary artery were performed by a single observer in 20 preterm infants, median gestation 27 weeks (range 24-31 weeks). Median age at study was 17 days (range 1-47 days). paired measurements of acceleration time (AT), ratio between acceleration time and right ventricular ejection time (AT:RVET), corrected AT, and corrected AT:RVET were compared to assess intraobserver agreement. For the corrected AT:RVET ratio, the mean percentage difference between observations was -0.9% (95% confidence intervals -5.0 to 3.1%). The limits of agreement for the two measurements were -26.3 to 24.5%. The coefficient of repeatability was 25.4%. Variation for other indices was similar. Non-invasive assessment of PAP using Doppler derived systolic time intervals is associated with considerable intraobserver variation. PMID:8795360

  11. Indicator system provides complete data of engine cylinder pressure variation

    NASA Technical Reports Server (NTRS)

    Mc Jones, R. W.; Morgan, N. E.

    1966-01-01

    Varying reference pressure used together with a balanced pressure pickup /a diaphragm switch/ to switch the electric output of the pressure transducer in a reference pressure line obtains precise engine cylinder pressure data from a high speed internal combustion engine.

  12. High Frequency Variations of Arctic Ocean Bottom Pressure and Their Relation to Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Peralta Ferriz, A. C.; Morison, J.; Kwok, R.

    2009-12-01

    The ocean bottom pressure (OBP) was measured at the North Pole from 2005 to 2008, as part of the North Pole Environmental Observatory. OBP shows a spectral peak at a period of about 19 days, which is consistent with modeling results of OBP from the PanArctic Ice-Ocean Model Assimilation System, PIOMAS. The OBP measured in the central Beaufort Sea from 2003 to 2008 as part of the Beaufort Gyre Exploration Project shows the same spectral peak. The variations in Beaufort Sea OBP are well correlated with those at the North Pole. This signal is also detected in the sea level pressure (SLP) records from the NCEP/NCAR re-analysis for the same time as the observations of OBP. Similarly, Morison [1990] found a spectral peak at 19 days in OBP observations across the West Spitsbergen Current, in Fram Strait. Here we explore two questions: What is the source of the 19-day period atmospheric signal and how is this signal transferred to the ocean. Based on satellite altimetry, it has been shown that the inverted barometer effect applies in the Arctic Ocean at daily to weekly time-scales [Kwok, et al., 2006]. Indeed, comparison of OBP from PIOMAS, which assumes a perfect inverted barometer, with observed OBP suggests that departures from the inverted barometer response are small. The fact that the PIOMAS OBP without direct atmosphere pressure loading shows a spectral peak that is similar to observed OBP, suggests that these oscillations are wind (pressure gradient) driven rather than due to direct atmospheric loading. The basin-averaged OBP variations from PIOMAS are well correlated with the atmospheric pressure over Scandinavia. This is consistent with a correlation between southerly winds in Fram Strait and the basin-averaged OBP, with the pressure lagging the wind by 1-2 days. Through examination of atmospheric pressure data and ice-ocean model results, we investigate the hypotheses that the SLP variation is related to the passage of planetary waves across the North Atlantic

  13. Ocean bottom pressure variation associated with path variations of the Kuroshio south of Japan

    NASA Astrophysics Data System (ADS)

    Nagano, Akira; Hasegawa, Takuya; Matsumoto, Hiroyuki; Ariyoshi, Keisuke

    2016-04-01

    The Kuroshio south of Japan takes a stable southward meandering path, called the large meander (LM), on interannual to decadal timescales. During the non-LM period, mesoscale disturbances of the Kuroshio path, called small meanders, occasionally occur in the region southeast of Kyushu and propagate eastward. Some of them develop to the LM, possibly associated with deep eddies. In order to reveal the relationship between the development of path disturbances and bottom current (or hydrostatic pressure), we examined variations of ocean bottom pressure obtained by pressure sensors deployed in the region off Shikoku (capes Ashizuri and Muroto). Bottom pressure on the continental slope is found to increase abruptly lagging a few months behind an elevation of sea surface height (SSH) due to the formation of the LM in July 2014. Geopotential distance from the sea surface to 2000 dbar based on hydrographic data at the Affiliated Surveys of the Kuroshio off Cape Ashizuri (ASUKA) line abruptly increases from early to late July. The reduction of density stratification, i.e., the weakened baroclinicity, causes the temporal delay of the increase of bottom pressure relative to the elevation of SSH associated with the formation of the LM.

  14. Micrometoric Impact Effects: Peak Pressure versus Spectral Variation

    NASA Technical Reports Server (NTRS)

    Jensen, Elizabeth; Lederer, S. M.; Wooden, D. H.; Lindsay, S. S.; Keller, L. P.; Cintala, M. J.; Zolensky, M. E.

    2013-01-01

    At the Experimental Impact Laboratory at NASA Johnson Space Center, we have investigated the surface properties of asteroids caused by collisions in the mid-infrared (2.5 to 16 microns) by impacting forsterite and enstatite across a range of velocities (as predicted by the Nice Model) and at varying temperatures. The crystal structure in these minerals can be deformed by the shock wave from the impact as well as sheared into smaller particle sizes. Our current focus is on the differing effects between 2.3 and 2.6 km/sec, as well as the differences between a cold sample at -20C and a room temperature sample at 25C. We find that the spectral variation and crystal deformation varies non-linearly with the peak shock pressure.

  15. Ice-Shelf Tidal Flexure and Subglacial Pressure Variations

    NASA Technical Reports Server (NTRS)

    Walker, Ryan T.; Parizek, Byron R.; Alley, Richard B.; Anandakrishnan, Sridhar; Riverman, Kiya L.; Christianson, Knut

    2013-01-01

    We develop a model of an ice shelf-ice stream system as a viscoelastic beam partially supported by an elastic foundation. When bed rock near the grounding line acts as a fulcrum, leverage from the ice shelf dropping at low tide can cause significant (approx 1 cm) uplift in the first few kilometers of grounded ice.This uplift and the corresponding depression at high tide lead to basal pressure variations of sufficient magnitude to influence subglacial hydrology.Tidal flexure may thus affect basal lubrication, sediment flow, and till strength, all of which are significant factors in ice-stream dynamics and grounding-line stability. Under certain circumstances, our results suggest the possibility of seawater being drawn into the subglacial water system. The presence of sea water beneath grounded ice would significantly change the radar reflectivity of the grounding zone and complicate the interpretation of grounded versus floating ice based on ice-penetrating radar observations.

  16. Variation of DNA Methylome of Zebrafish Cells under Cold Pressure.

    PubMed

    Han, Bingshe; Li, Wenhao; Chen, Zuozhou; Xu, Qiongqiong; Luo, Juntao; Shi, Yingdi; Li, Xiaoxia; Yan, Xiaonan; Zhang, Junfang

    2016-01-01

    DNA methylation is an essential epigenetic mechanism involved in multiple biological processes. However, the relationship between DNA methylation and cold acclimation remains poorly understood. In this study, Methylated DNA Immunoprecipitation Sequencing (MeDIP-seq) was performed to reveal a genome-wide methylation profile of zebrafish (Danio rerio) embryonic fibroblast cells (ZF4) and its variation under cold pressure. MeDIP-seq assay was conducted with ZF4 cells cultured at appropriate temperature of 28°C and at low temperature of 18°C for 5 (short-term) and 30 (long-term) days, respectively. Our data showed that DNA methylation level of whole genome increased after a short-term cold exposure and decreased after a long-term cold exposure. It is interesting that metabolism of folate pathway is significantly hypomethylated after short-term cold exposure, which is consistent with the increased DNA methylation level. 21% of methylation peaks were significantly altered after cold treatment. About 8% of altered DNA methylation peaks are located in promoter regions, while the majority of them are located in non-coding regions. Methylation of genes involved in multiple cold responsive biological processes were significantly affected, such as anti-oxidant system, apoptosis, development, chromatin modifying and immune system suggesting that those processes are responsive to cold stress through regulation of DNA methylation. Our data indicate the involvement of DNA methylation in cellular response to cold pressure, and put a new insight into the genome-wide epigenetic regulation under cold pressure. PMID:27494266

  17. Variation of DNA Methylome of Zebrafish Cells under Cold Pressure

    PubMed Central

    Xu, Qiongqiong; Luo, Juntao; Shi, Yingdi; Li, Xiaoxia; Yan, Xiaonan; Zhang, Junfang

    2016-01-01

    DNA methylation is an essential epigenetic mechanism involved in multiple biological processes. However, the relationship between DNA methylation and cold acclimation remains poorly understood. In this study, Methylated DNA Immunoprecipitation Sequencing (MeDIP-seq) was performed to reveal a genome-wide methylation profile of zebrafish (Danio rerio) embryonic fibroblast cells (ZF4) and its variation under cold pressure. MeDIP-seq assay was conducted with ZF4 cells cultured at appropriate temperature of 28°C and at low temperature of 18°C for 5 (short-term) and 30 (long-term) days, respectively. Our data showed that DNA methylation level of whole genome increased after a short-term cold exposure and decreased after a long-term cold exposure. It is interesting that metabolism of folate pathway is significantly hypomethylated after short-term cold exposure, which is consistent with the increased DNA methylation level. 21% of methylation peaks were significantly altered after cold treatment. About 8% of altered DNA methylation peaks are located in promoter regions, while the majority of them are located in non-coding regions. Methylation of genes involved in multiple cold responsive biological processes were significantly affected, such as anti-oxidant system, apoptosis, development, chromatin modifying and immune system suggesting that those processes are responsive to cold stress through regulation of DNA methylation. Our data indicate the involvement of DNA methylation in cellular response to cold pressure, and put a new insight into the genome-wide epigenetic regulation under cold pressure. PMID:27494266

  18. Pluto's Insolation History: Latitudinal Variations and Effects on Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Earle, Alissa M.; Binzel, Richard P.

    2014-11-01

    Since previous insolation modeling in the early 1990’s, new atmospheric pressure data, increased computational power, and the upcoming flyby of the Pluto system by NASA’s New Horizons spacecraft have generated new motivation and increased capabilities for the study of Pluto’s complex long-term (million-years) insolation history. The two primary topics of interest in studying Pluto’s insolation history are the variations in insolation patterns when integrated over different intervals and the evolution of diurnal insolation patterns over the last several decades. We find latitudinal dichotomies when comparing average insolation over timescales of days, decades, centuries, and millennia. Depending on the timescales of volatile migration, some consequences of these insolation patterns may be manifested in the surface features revealed by New Horizons. For any single rotation of Pluto there is a latitude that receives more insolation relative to the others. Often this is the sub-subsolar latitude but it can also be an arctic circle latitude when near-polar regions of Pluto experience the "midnight sun". We define the amount of that greatest insolation value over the course of one rotation as the "maximum diurnal insolation" (MDI). We find that MDI is driven to its highest values when Pluto’s obliquity creates a long arctic summer (or “midnight sun”) beginning just after perihelion. Pluto’s atmospheric pressure, as measured through stellar occultation observations during the past three decades, appears to correlate with Pluto's currently occurring midnight sun as quantified by the MDI parameter. If insolation (as parameterized by the MDI value) is the single dominant factor driving Pluto's atmospheric pressure, this “Midnight Sun Model” predicts that Pluto's maximum atmospheric pressure will be reached in 2017 followed by a steady decline. Pluto's maximum diurnal insolation value begins dropping after 2017 due to two factors: Pluto’s sub-solar point

  19. Pulse pressure variation and stroke volume variation under different inhaled concentrations of isoflurane, sevoflurane and desflurane in pigs undergoing hemorrhage

    PubMed Central

    Oshiro, Alexandre Hideaki; Otsuki, Denise Aya; Hamaji, Marcelo Waldir M; Rosa, Kaleizu T; Ida, Keila Kazue; Fantoni, Denise T; Auler, José Otavio Costa

    2015-01-01

    OBJECTIVES: Inhalant anesthesia induces dose-dependent cardiovascular depression, but whether fluid responsiveness is differentially influenced by the inhalant agent and plasma volemia remains unknown. The aim of this study was to compare the effects of isoflurane, sevoflurane and desflurane on pulse pressure variation and stroke volume variation in pigs undergoing hemorrhage. METHODS: Twenty-five pigs were randomly anesthetized with isoflurane, sevoflurane or desflurane. Hemodynamic and echocardiographic data were registered sequentially at minimum alveolar concentrations of 1.00 (M1), 1.25 (M2), and 1.00 (M3). Then, following withdrawal of 30% of the estimated blood volume, these data were registered at a minimum alveolar concentrations of 1.00 (M4) and 1.25 (M5). RESULTS: The minimum alveolar concentration increase from 1.00 to 1.25 (M2) decreased the cardiac index and increased the central venous pressure, but only modest changes in mean arterial pressure, pulse pressure variation and stroke volume variation were observed in all groups from M1 to M2. A significant decrease in mean arterial pressure was only observed with desflurane. Following blood loss (M4), pulse pressure variation, stroke volume variation and central venous pressure increased (p<0.001) and mean arterial pressure decreased in all groups. Under hypovolemia, the cardiac index decreased with the increase of anesthesia depth in a similar manner in all groups. CONCLUSION: The effects of desflurane, sevoflurane and isoflurane on pulse pressure variation and stroke volume variation were not different during normovolemia or hypovolemia. PMID:26735220

  20. Integrating environmental variation, predation pressure, phenotypic plasticity and locomotor performance.

    PubMed

    Fu, Shi-Jian; Cao, Zhen-Dong; Yan, Guan-Jie; Fu, Cheng; Pang, Xu

    2013-10-01

    The Wujiang River, a tributary of the Three Gorges Reservoir, has many dams along its length. These dams alter the river's natural habitat and produce various flow regimes and degrees of predator stress. To test whether the swimming performance and external body shape of pale chub (Zacco platypus) have changed as a result of alterations in the flow regime and predator conditions, we measured the steady (U(crit)) and unsteady (fast-start) swimming performances and morphological characteristics of fish collected from different sites along the Wujiang River. We also calculated the maximum respiratory capacity and cost of transport (COT). We demonstrated significant differences in swimming performance and morphological traits among the sampling sites. Steady swimming performance was positively correlated with water velocity and negatively correlated with the abundance of predators, whereas unsteady swimming performance was negatively correlated with water velocity. The body shape was significantly correlated with both swimming performance and ecological parameters. These findings suggested that selection pressure on swimming performance results in a higher U(crit) and a more streamlined body shape in fast-flow and (or) in habitats with low predator stress and subsequently results in a lower COT. These characteristics were accompanied by a poorer fast-start performance than that of the fish from the slow-flow and (or) high-predator habitats. The divergence in U(crit) may also be due in part to variation in respiratory capacity. PMID:23463244

  1. [Production and law of variation of the pleural cavity intrinsic pressure and the pressure of alveolar wall during respiratory process].

    PubMed

    Zhang, Shenghua; Qin, Renjia

    2012-04-01

    All physiologic textbooks deal with pleural cavity pressure, alveolar wall pressure and pressure inside the lung, but they have not stated these ideas clearly. The present study reveals production and Law of variation of the intrinsic pressure of pleural cavity, the pressure of alveolar wall and the intrinsic pressure in the alveoli. Pleural cavity intrinsic pressure is produced by the pressure from pleura expanding or compressing force of the lungs. When the lungs calmly inhale, the thorax expands, pleural cavity negative pressure increase. When the lungs calmly exhale, thorax reduces, but thorax and lungs are still in the extended state, pleural cavity is still in negative pressure. With thorax reducing, negative pressure decreases. When the lungs are at the forced expiration, the lung pleura and wall pleura extrude pleural cavity, only to produce positive pressure. The pressure of alveolar wall is the algebraic sum of the intrinsic pressure of pleural cavity, the intrinsic pressure of pulmonary tissue and the additional pressure of alveolar wall. We did the calculation of additional pressure on the alveolar wall by using Laplace formula of spherical elastic membrane. The intrinsic pressure of alveoli depends on the moving speed or slowness of expansion or compression of alveolar wall and the size of trachea resistance. PMID:22616171

  2. Pulse pressure variation and stroke volume variation to predict fluid responsiveness in patients undergoing carotid endarterectomy

    PubMed Central

    Kim, Kyung Mi; Choi, Soo Joo; Kim, Myung Hee; Park, Mi Hye; Heo, Burn Young

    2013-01-01

    Background During carotid endarterectomy (CEA), hemodynamic stability and adequate fluid management are crucial to prevent perioperative cerebral stroke, myocardial infarction and hyperperfusion syndrome. Both pulse pressure variation (PPV) and stroke volume variation (SVV), dynamic preload indices derived from the arterial waveform, are increasingly advocated as predictors of fluid responsiveness in mechanically ventilated patients. The aim of this study was to evaluate the accuracy of PPV and SVV for predicting fluid responsiveness in patients undergoing CEA. Methods Twenty seven patients undergoing CEA were enrolled in this study. PPV, SVV and cardiac output (CO) were measured before and after fluid loading of 500 ml of hydroxyethyl starch solution. Fluid responsiveness was defined as an increase in CO ≥ 15%. The ability of PPV and SVV to predict fluid responsiveness was assessed using receiver operating characteristic (ROC) analysis. Results Both PPV and SVV measured before fluid loading are associated with changes in CO caused by fluid expansion. The ROC analysis showed that PPV and SVV predicted response to volume loading (area under the ROC curve = 0.854 and 0.841, respectively, P < 0.05). A PPV ≥ 9.5% identified responders (Rs) with a sensitivity of 71.4% and a specificity of 90.9%, and a SVV ≥ 7.5% identified Rs with a sensitivity of 92.9% and a specificity of 63.6%. Conclusions Both PPV and SVV values before volume loading are associated with increased CO in response to volume expansion. Therefore, PPV and SVV are useful predictors of fluid responsiveness in patients undergoing CEA. PMID:24101958

  3. Observation of pressure variation in the cavitation region of submerged journal bearings

    NASA Technical Reports Server (NTRS)

    Etsion, I.; Ludwig, L. P.

    1980-01-01

    Visual observations and pressure measurements in the cavitation zone of a submerged journal bearing are described. Tests were performed at various shaft speeds and ambient pressure levels. Some photographs of the cavitation region are presented showing strong reverse flow at the downstream end of the region. Pressure profiles are presented showing significant pressure variations inside the cavitation zone, contrary to common assumptions of constant cavitation pressure.

  4. Variation of Azeotropic Composition and Temperature with Pressure

    ERIC Educational Resources Information Center

    Gibbard, H. Frank; Emptage, Michael R.

    1975-01-01

    Describes an undergraduate physical chemistry experiment in which an azeotropic mixture is studied using the vapor pressures of the components as functions of temperature and the azeotropic composition and temperature at one pressure. Discusses in detail the mathematical treatment of obtained thermodynamic data. (MLH)

  5. Variation of Thermal Pressure along the Solid Hugoniot

    NASA Astrophysics Data System (ADS)

    Yu, Hui; Jing, Fuqian

    2005-07-01

    The behavior of thermal pressure PTH for all kinds of solid materials were investigated by using lattice dynamics theory and shock wave theory along the Hugoniot up to 500GPa. The results showed that for metals, ionic crystal and miners, etc., the ratio of the thermal pressure to the total pressure (PTH /PTotal) is approximately keeping in constant in a large pressure range not only for non-porous materials but also for porous materials at certain porosity. This confirms theoretically the existence of material constant parameter β along solid Hugoniot (Gong et al., Shock Compression of Condensed Matter-2003, edited by M. D. Furnish, Y. m. Gupta, and J. W. Forfes, pp.61-64.). Moreover, the volume dependence of the thermal pressure for all kinds of materials was addressed in our paper.

  6. Pressure variation of reentrant transition temperature in liquid crystals.

    PubMed

    Srivastava, A; Sa, D; Singh, S

    2007-02-01

    High pressure experimental studies show that in certain mesogenic materials, the nematic-smectic A (N-Sm A) transition temperature T(AN) exhibits nonlinear pressure dependence. As a consequence, the material shows reentrant phenomena that is a phase sequence nematic -- smectic A -- reentrant nematic appears. The characteristic features of this phenomenon have been addressed here within the framework of Landau-de-Gennes theory, where the coupling between nematic and smectic A order parameters (gamma, lambda(eff)) plays an important role. The cubic coupling gamma is chosen to be negative in order to form Sm A phase whereas the biquadratic coupling lambda(eff) is made large and positive to obtain reentrant behaviour. In the present work, we incorporate the pressure dependence in the theory through gamma and lambda(eff) which justifies the experimental pressure dependence in the reentrant transition temperature [Formula: see text]. The pressure dependence of gamma and lambda(eff) are employed in the calculation of excess specific heat capacity near the reentrant transition. The computed heat capacity shows strong pressure dependence near the reentrant transition which can be confirmed from high pressure measurement. PMID:17342375

  7. [The neuroanatomical and physiological bases of variations in intraocular pressure].

    PubMed

    Chiquet, C; Denis, P

    2004-09-01

    Intraocular pressure displays a distinct circadian rhythm in animals and humans, with an increase at night and a decrease during the daytime. In animals, the IOP rhythm has been reported to be synchronized by environmental light and to persist in constant darkness, demonstrating a circadian component controlled by an endogenous pacemaker. The structures involved in the rhythmic regulation of intraocular pressure include the suprachiasmatic nucleus, which controls the activity of sympathetic and parasympathetic ocular innervation. These effectors are responsible for controlling the production (beta-adrenergic system) and the outflow (alpha1-adrenergic, parasympathetic system, prostaglandin) of aqueous humor. The production of aqueous humor is under adrenergic control (alpha1- and beta-receptors). Many neuropeptides such as vasoactive intestinal peptide, substance P, and the atrial natriuretic peptide are also involved in the regulation of intraocular pressure. A better understanding of the circadian regulation of intraocular pressure is needed for an appropriate treatment of ocular hypertension and glaucoma. PMID:15314570

  8. Transmitted ultrasound pressure variation in micro blood vessel phantoms.

    PubMed

    Qin, Shengping; Kruse, Dustin E; Ferrara, Katherine W

    2008-06-01

    Silica, cellulose and polymethylmethacrylate tubes with inner diameters of ten to a few hundred microns are commonly used as blood vessel phantoms in in vitro studies of microbubble or nanodroplet behavior during insonation. However, a detailed investigation of the ultrasonic fields within these micro-tubes has not yet been performed. This work provides a theoretical analysis of the ultrasonic fields within micro-tubes. Numerical results show that for the same tube material, the interaction between the micro-tube and megaHertz-frequency ultrasound may vary drastically with incident frequency, tube diameter and wall thickness. For 10 MHz ultrasonic insonation of a polymethylmethacrylate (PMMA) tube with an inner diameter of 195 microm and an outer diameter of 260 microm, the peak pressure within the tube can be up to 300% of incident pressure amplitude. However, using 1 MHz ultrasound and a silica tube with an inner diameter of 12 microm and an outer diameter of 50 microm, the peak pressure within the tube is only 12% of the incident pressure amplitude and correspondingly, the spatial-average-time-average intensity within the tube is only 1% of the incident intensity. PMID:18395962

  9. Variation of Fracturing Pressures with Depth Near the Valles Caldera

    SciTech Connect

    Dash, Zora; Murphy, Hugh

    1983-12-15

    Hydraulic Fracturing at the Fenton Hill Hot Dry Rock Geothermal site near the Valles Caldera has yielded fracturing pressures from 14 to 81 MPa (2030 to 11,750 psi) at depths ranging from 0.7 to 4.4 km (2250 to 14,400 ft). This data can be fit to a fracture gradient of 19 MPa/km (0.84 psi/ft), except for an anomalous region between 2.6 to 3.2 km where fracturing pressures are about 20 MPa lower than estiamted using the above gradient. This anomaly coincides with a biotite granodiorite intrusive emplaced into a heterogeneous jointed metamorphic complex comprised of gneisses, schists and metavolcanic rocks. Microseismic events detected with sensitive downhole geophones suggest that shear failure is an important process during hydraulic fracturing of such jointed rock. Consequently the usual relation between minimum earth stress and fracture opening pressure, based upon classic tensile failure, cannot be used apriori; fracture opening pressure is instead a complex function of joint orientation and all three components of principal earth stress.

  10. Transmitted Ultrasound Pressure Variation in Micro Blood Vessel Phantoms

    PubMed Central

    Qin, Shengping; Kruse, Dustin E.; Ferrara, Katherine W.

    2008-01-01

    Silica, cellulose, and polymethylmethacrylate tubes with inner diameters of ten to a few hundred microns are commonly used as blood vessel phantoms in in vitro studies of microbubble or nanodroplet behavior during insonation. However, a detailed investigation of the ultrasonic fields within these micro-tubes has not yet been performed. This technical note provides a theoretical analysis of the ultrasonic fields within micro-tubes. Numerical results show that for the same tube material, the interaction between the micro-tube and megaHertz-frequency ultrasound may vary drastically with incident frequency, tube diameter, and wall thickness. For 10 MHz ultrasonic insonation of a polymethylmethacrylate (PMMA) tube with an inner diameter of 195 μm and an outer diameter of 260 μm, the peak pressure within the tube can be up to 300% of incident pressure amplitude. However, using 1 MHz ultrasound and a silica tube with an inner diameter of 12 μm and an outer diameter of 50 μm, the peak pressure within the tube is only 12% of the incident pressure amplitude, and correspondingly the spatial-average-time-average intensity within the tube is only 1% of the incident intensity. PMID:18395962

  11. Static Pressure Distribution in the Distant Tail Lobe and Compressional Variations Observed by Geotail

    NASA Astrophysics Data System (ADS)

    Matsuoka, A.

    2003-12-01

    In order to study the dynamics of the magnetosphere, it is important to know the temporal variation and spatial distribution of the static pressure. The static pressure in the magnetotail basically depends on the distance from the earth and also on the solar wind condition. We have statistically analyzed the static pressure measured by GEOTAIL in the magnetotail (X < -40 RE) and extracted an empirical equation to express the static pressure in the tail lobe by the solar wind parameters. In the calm magnetosphere, the total pressure in the tail lobe is often smaller than the static pressure in the solar wind (<74%). For more than 90 % of the 30-minutes averaged data, the deviation of the measured pressure from the expected one is found to be within 50 %. On the other hand, substantial deviations of the measured static pressure from the expected one are often caused by the passage of plasmoids. An example of the static pressure variation in the distant magnetotail lobe caused by the passage of a plasmoid is investigated in detail. The traveling speed of the plasmoid is estimated to have been faster than the concurrent magnetosonic speed in the lobe. The magnetic field variation along the maximum variance direction was linearly related to the variation in the field strength, which suggests that a magneto-hydrodynamic compressional mode might have occurred. The propagation direction of the variation is determined from the background field direction and the maximum variance direction of the field. Shortly after the passage of the plasmoid, the relation between the field and velocity variations is consistent with the fast mode. Pressure variation in the fast mode was possibly generated in the trail of the plasmoid to restore equilibrium.

  12. Pressure Variations in Metamorphic Rocks: Implications for the Interpretation of Petrographic Observations

    NASA Astrophysics Data System (ADS)

    Tajčmanová, Lucie

    2014-05-01

    Metamorphic petrologists and structural geologists, using direct measurements, bring the only direct observational constrains for validating geodynamic models. Therefore, petrological and structural geological observations are essential for the quality and reproducibility of geodynamic reconstructions and models. One of the important assumptions for geodynamic reconstructions arises from the pressure and temperature estimates in the petrology analysis. Pressure is commonly converted to depth through the equation for lithostatic pressure and so the original position of the rock sample within the Earth's interior can be constrained. The current assumption that the studied sample corresponds to uniform pressure may not be correct, and if so, it has serious implications. Increasing evidence from analytical data shows that pressure is not constant even on a grain scale, posing new challenges because, if ignored, it leads to an incorrect use of petrology data in constraining geodynamic models. Well known examples of the preservation of coesite and diamond in a host mineral like garnet show that high pressure inclusions are preserved during decompression. Tajčmanová et al. (2014) has shown that grain-scale pressure variations can develop and that these pressure variations allow compositional zoning in minerals preserved over geological time scales. A new unconventional barometric method based on equilibrium under pressure variations has been developed . Such pressure variations are also connected with differences in fluid pressure in open systems and can be thus observed at all scales. Tajčmanová L., Podladchikov Y., Powell R., Moulas E., Vrijmoed J. and Connolly J. (2014). Grain scale pressure variations and chemical equilibrium in high-grade metamorphic rocks.Journal of Metamorphic Geology, doi:10.1111/jmg.12066 This work was supported by ERC starting grant 335577 to Lucie Tajcmanova

  13. A method to account for variation of average compressor inlet pressure during instantaneous distortion analyses

    NASA Technical Reports Server (NTRS)

    Burstadt, P. L.; Wenzel, L. M.

    1976-01-01

    A method is presented to calculate the available surge margin as a function of time and incorporate it into an instantaneous distortion analysis. Results show that inlet pressure variations which cause only a small change at the compressor exit can cause a significant variation in the available surge margin.

  14. 40 CFR 53.56 - Test for effect of variations in ambient pressure.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... to exceed 5 minutes. (5) Flow measurement adaptor (40 CFR part 50, appendix L, figure L-30) or... section 6 of 40 CFR part 50, appendix L (if required). (d) Calibration of test measurement instruments... variations in ambient (barometric) pressure. Tests shall be conducted in a pressure-controlled...

  15. 40 CFR 53.56 - Test for effect of variations in ambient pressure.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... to exceed 5 minutes. (5) Flow measurement adaptor (40 CFR part 50, appendix L, figure L-30) or... section 6 of 40 CFR part 50, appendix L (if required). (d) Calibration of test measurement instruments... variations in ambient (barometric) pressure. Tests shall be conducted in a pressure-controlled...

  16. 40 CFR 53.56 - Test for effect of variations in ambient pressure.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... to exceed 5 minutes. (5) Flow measurement adaptor (40 CFR part 50, appendix L, figure L-30) or... section 6 of 40 CFR part 50, appendix L (if required). (d) Calibration of test measurement instruments... variations in ambient (barometric) pressure. Tests shall be conducted in a pressure-controlled...

  17. Static pressure distribution in the distant tail lobe and compressional variations observed by Geotail

    NASA Astrophysics Data System (ADS)

    Matsuoka, A.

    We have statistically analyzed the static pressure (summation of the ion thermal pressure, electron thermal pressure, and magnetic pressure) measured by GEOTAIL in the tail lobe of the distance beyond 40 Re. In the mid-tail (X > -60 Re) the static pressure decreases with the distance from the earth, reflecting the flaring of the magnetosphere. In the distant tail (X < -60 Re) the static pressure is nearly equal to the static pressure of the solar wind. When the electron temperature in the solar wind is assumed to be 141000 K after Newbury et al. [1998], the total pressure in the distant tail lobe (X < -150 Re)is generally smaller than the static pressure in the solar wind (86%). On the other hand, when we assume lower electron temperature down to 103000K, the ratio between the two pressures becomes the unity. It may be attributed to the error of the electron temperature in the solar wind, the inverse-flaring of the magnetosphere. We extracted an empirical equation to express the static pressure in the lobe by the solar wind parameters. In 87% of the total data set the difference between the measured pressure and the estimated one by the equation is within 20%. On the other hand, substantial deviations of the measured static pressure from the expected one are often caused by the passage of plasmoids. An example of the static pressure variation in the distant magnetotail lobe caused by the passage of a plasmoid is investigated in detail. The traveling speed of the plasmoid is estimated to have been faster than the concurrent magnetosonic speed in the lobe. The magnetic field variation along the maximum variance direction was linearly related to the variation in the field strength, which suggests that a magneto-hydrodynamic compressional mode might have occurred. The propagation direction of the variation is determined from the background field direction and the maximum variance direction of the field. Shortly after the passage of the plasmoid, the relation between

  18. Analysis of Pressure Variations in a Low-Pressure Nickel-Hydrogen Battery– Part 2: Cells with Metal Hydride Storage

    PubMed Central

    Purushothaman, B. K.; Wainright, J. S.

    2012-01-01

    A sub-atmospheric pressure nickel hydrogen (Ni-H2) battery with metal hydride for hydrogen storage is developed for implantable neuroprosthetic devices. Pressure variations during charge and discharge of the cell are analyzed at different states of charge and are found to follow the desorption curve of the pressure composition isotherm (PCI) of the metal hydride. The measured pressure agreed well with the calculated theoretical pressure based on the PCI and is used to predict the state of charge of the battery. Hydrogen equilibration with the metal hydride during charge/discharge cycling is fast when the pressure is in the range from 8 to 13 psia and slower in the range from 6 to 8 psia. The time constant for the slower hydrogen equilibration, 1.37h, is similar to the time constant for oxygen recombination and therefore pressure changes due to different mechanisms are difficult to estimate. The self-discharge rate of the cell with metal hydride is two times lower in comparison to the cell with gaseous hydrogen storage alone and is a result of the lower pressure in the cell when the metal hydride is used. PMID:22711974

  19. Lack of seasonal variation in blood pressure in patients on hemodialysis in a North American center.

    PubMed

    Fine, A

    2000-09-01

    Seasonal variation in blood pressure in patients undergoing hemodialysis in Europe has recently been described. If confirmed, this has important therapeutic, research, and epidemiological implications. All normotensive patients not administered antihypertensive drugs in our unit were studied. Predialysis blood pressures were measured before each dialysis treatment over two 2-month periods, January through February and July through August, in Winnipeg, Canada, a city with one of the most extreme seasonal temperature variations in North America. No difference in blood pressures was found between summer and winter (141 +/- 5/75 +/- 2 versus 140 +/- 4/74 +/- 2 mm Hg; P = not significant). Average daily temperatures were -16 degrees C in winter and 23 degrees C in summer. Interdialytic weight gain was the same in both groups. In conclusion, season has no effect on blood pressure in hemodialysis patients in a North American center. Reported seasonal changes in blood pressure in Europe may be related to nonclimatic factors. PMID:10977788

  20. Pressure variations on a train - Where is the threshold to railway passenger discomfort?

    PubMed

    Schwanitz, Sandra; Wittkowski, Martin; Rolny, Vinzent; Basner, Mathias

    2013-03-01

    The implementation of recent guidelines for tunnel construction in Germany leads to extended air pressure variations inside trains and reduces pressure comfort for railway passengers. A questionnaire survey with 262 passengers revealed that pressure variations are rated less important for riding comfort than climatic and spatial aspects (study 1). A laboratory experiment (study 2) in the pressure chamber at the DLR Institute of Aerospace Medicine with 31 subjects (mean age = 37.7, SD = 12.7; 51.6% male) investigated the effects of systematic pressure variations on discomfort. The pressure changes (pressure increases and decreases) ranged from 1 to 100 mbar and were realized within 1-100 s. We derived thresholds for healthy passengers by means of random effects linear and logistic regression analysis. Logistic dose-response curves revealed amplitude/time combinations leading to a certain percentage of passengers perceiving discomfort (e.g. 50% dissatisfied passengers regarding a pressure increase of approximately 30 mbar within 5 s). The findings may help design engineers to meet passengers' comfort requirements. PMID:22884634

  1. The Genetics of Blood Pressure and Hypertension: the role of rare variation

    PubMed Central

    Doris, Peter A.

    2013-01-01

    Summary The role of heredity in influencing blood pressure and risk of hypertension is well recognized. However, progress in identifying specific genetic variation that contributes to heritability is very limited. This is in spite of completion of the human genome sequence, the development of extraordinary amounts of information about genome sequence variation and the investigation of blood pressure inheritance in linkage analysis, candidate gene studies and, most recently genome-wide association studies. This paper considers the progress of this research and the obstacles that have been encountered. This work has made clear that the genetic architecture of blood pressure regulation in the population is not likely to be shaped by commonly occurring genetic variation in a discrete set of blood pressure-influencing genes. Rather heritability may be accounted for by rare variation that has its biggest impact within pedigrees rather than on the population at large. Rare variants in a wide range of genes are likely to be the focus of high blood pressure genetics for the next several years and the emerging strategies that can be applied to uncover this genetic variation and the problems that must confronted are considered. PMID:21129164

  2. Selective Pressure along a Latitudinal Gradient Affects Subindividual Variation in Plants

    PubMed Central

    Sobral, Mar; Guitián, José; Guitián, Pablo; Larrinaga, Asier R.

    2013-01-01

    Individual plants produce repeated structures such as leaves, flowers or fruits, which, although belonging to the same genotype, are not phenotypically identical. Such subindividual variation reflects the potential of individual genotypes to vary with micro-environmental conditions. Furthermore, variation in organ traits imposes costs to foraging animals such as time, energy and increased predation risk. Therefore, animals that interact with plants may respond to this variation and affect plant fitness. Thus, phenotypic variation within an individual plant could be, in part, an adaptive trait. Here we investigated this idea and we found that subindividual variation of fruit size of Crataegus monogyna, in different populations throughout the latitudinal gradient in Europe, was explained at some extent by the selective pressures exerted by seed-dispersing birds. These findings support the hypothesis that within-individual variation in plants is an adaptive trait selected by interacting animals which may have important implications for plant evolution. PMID:24069297

  3. On the relationship between the Martian pressure changes and the MSL/RAD dose rate variations

    NASA Astrophysics Data System (ADS)

    Guo, Jingnan; Wimmer-Schweingruber, Robert; zeitlin, Cary; Rafkin, Scot; Koehler, Jan; Hassler, Donald; Ehresmann, Bent; Appel, Jan; Boehm, Eckart; Boettcher, Stephan; Brinza, David; Burmeister, Soenke; Lohf, Henning; Martin, Cesar; Posner, Arik; Reitz, Guenther

    2015-04-01

    The Radiation Assessment Detector (RAD) onboard the Mars Science Laboratory's (MSL) rover Curiosity measures the radiation dose rate at the surface of Mars. With these first-ever measurements on the Martian surface, RAD observed the diurnal variations of the total dose rate and neutron count rate due to changes in atmospheric column mass driven by the atmospheric thermal tide tep{rafkin2014}. Variations in the dose rate are shown to be anti-correlated with the changes in atmospheric shielding, while the neutron count rate shows a positive-correlation with the changes of atmospheric pressure. We have analyzed this cyclic variations in the longer term and discovered a second-order effect of this diurnal correlation which indicates a non-linear pressure-dose rate effect. We also employed a PLANETOCOSMIC simulation which shows as well a non-linear correlation between pressure and particles fluxes on the surface of Mars.

  4. Characterization and Prediction of Subsurface Pneumatic PressureVariations at Yucca Mountain, Nevada

    SciTech Connect

    Ahlers, C. Fredrik; Finsterle, Stefan; Bodvarsson, Gudmundur S.

    1998-01-02

    Yucca Mountain, Nevada is being investigated as the proposed site for geologic disposal of high level nuclear waste. A massive data collection effort for characterization of the unsaturated zone is being carried out at the site. The USGS is monitoring the subsurface pressure variations due to barometric pumping in several boreholes. Numerical models are used to simulate the observed subsurface pressure variations. Data inversion is used to characterize the unsaturated system and estimate the pneumatic diffusivity of important geologic features. Blind predictions of subsurface response and subsequent comparison to recorded data have built confidence in the models of Yucca Mountain.

  5. A flamelet model for supersonic non-premixed combustion with pressure variation

    NASA Astrophysics Data System (ADS)

    Zhao, Guo-Yan; Sun, Ming-Bo; Wu, Jin-Shui; Wang, Hong-Bo

    2015-08-01

    A modified flamelet model is proposed for studying supersonic combustion with pressure variation considering that pressure is far from homogenous in a supersonic combustor. In this model, the flamelet database are tabulated at a reference pressure, while quantities at other pressure are obtained using a sixth-order polynomial in pressure. Attributed to merit of the modified model which compute coefficients for the expansion only. And they brought less requirements for memory and table lookup time, expensive cost is avoided. The performance of modified model is much better than the approach of using a flamelet model-based method with tabulation at different pressure values. Two types of hydrogen fueled scramjet combustors were introduced to validate the modified flamelet model. It was observed that the temperature is sensitive to the choice of model in combustion area, which in return will significantly affect the pressure. It was found that the results of modified model were in good agreement with the experimental data compared with the isobaric flamelet model, especially for temperature, whose value is more accurately predicted. It is concluded that the modified flamelet model was more effective for cases with a wide range of pressure variation.

  6. The variation with Reynolds number of pressure distribution over an airfoil section

    NASA Technical Reports Server (NTRS)

    Pinkerton, Robert M

    1938-01-01

    Pressures were simultaneously measured at 54 orifices distributed over the midspan section of a 5 by 30-inch rectangular model of the NACA 4412 airfoil in the variable-density tunnel. These measurements were made at 17 angles of attack from -20 degrees to 30 degrees for eight values of the effective Reynolds number form approximately 100,000 to 8,200,000. Accurate data were thus obtained for studying the variation of pressure distribution with Reynolds number. These results on the NACA 4412 section indicated that the pressure distribution is practically unaffected by changes in Reynolds number except where separation is involved.

  7. DNS of transcritical turbulent boundary layers at supercritical pressures under abrupt variations in thermodynamic properties

    NASA Astrophysics Data System (ADS)

    Kawai, Soshi

    2014-11-01

    In this talk, we first propose a numerical strategy that is robust and high-order accurate for enabling to simulate transcritical flows at supercritical pressures under abrupt variations in thermodynamic properties due to the real fluid effects. The method is based on introducing artificial density diffusion in a physically-consistent manner in order to capture the steep variation of thermodynamic properties in transcritical conditions robustly, while solving a pressure evolution equation to achieve pressure equilibrium at the transcritical interfaces. We then discuss the direct numerical simulation (DNS) of transcritical heated turbulent boundary layers on a zero-pressure-gradient flat plate at supercritical pressures. To the best of my knowledge, the present DNS is the first DNS of zero-pressure-gradient flat-plate transcritical turbulent boundary layer. The turbulent kinetic budget indicates that the compressibility effects (especially, pressure-dilatation correlation) are not negligible at the transcritical conditions even if the flow is subsonic. The unique and interesting interactions between the real fluid effects and wall turbulence, and their turbulence statistics, which have never been seen in the ideal-fluid turbulent boundary layers, are also discussed. This work was supported in part by Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for Young Scientists (A) KAKENHI 26709066 and the JAXA International Top Young Fellowship Program.

  8. A method to account for variation of average compressor inlet pressure during instantaneous distortion analyses

    NASA Technical Reports Server (NTRS)

    Burstadt, P. L.; Wenzel, L. M.

    1976-01-01

    Instantaneous distortion analyses compare a time-varying value of an index (or 'surge margin used up') with a critical level (or 'available surge margin' of the compressor) to determine inlet-engine compatibility. Unless freestream conditions or propulsion system controls are changing, it is generally assumed that the available surge margin of the compressor is accurately determined from the steady-state operating point. Results are presented which show that variations of average compressor inlet pressure may occur without changes in freestream conditions or propulsion system controls. The volume dynamics of the compressor will cause these pressure variations to be attenuated and delayed by the time they reach the exit. This will cause the compressor pressure ratio (and available surge margin) to vary with time. A method is presented to calculate the available surge margin as a function of time and incorporate it into an instantaneous distortion analysis. Results show that inlet pressure variations which cause only a small change at the compressor exit can cause a significant variation in the available surge margin.

  9. 40 CFR 53.56 - Test for effect of variations in ambient pressure.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Test for effect of variations in ambient pressure. 53.56 Section 53.56 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) AMBIENT AIR MONITORING REFERENCE AND EQUIVALENT METHODS Procedures for Testing Physical (Design) and...

  10. Pressure-induced variation of structural, elastic, vibrational, electronic, thermodynamic properties and hardness of Ruthenium Carbides

    NASA Astrophysics Data System (ADS)

    Gopalakrishna Pillai, Harikrishnan; Kulangara Madam, Ajith; Natarajan, Sathish; Chandra, Sharat; Mundachali Cheruvalath, Valsakumar

    2016-07-01

    Three of the five structures obtained from the evolutionary algorithm based structure search of Ruthenium Carbide systems in the stoichiometries RuC, Ru2C and Ru3C are relaxed at different pressures in the range 0-200 GPa and the pressure-induced variation of their structural, elastic, dynamical, electronic and thermodynamic properties as well as hardness is investigated in detail. No structural transition is present for these systems in this pressure range. RuC-Zinc blende is mechanically and dynamically unstable close to 100 GPa. RuC-Rhombohedral and Ru3C-Hexagonal retain mechanical and dynamical stability up to 200 GPa. For all three systems the electronic bands and density of states spread out with pressure and the band gap increases with pressure for the semiconducting RuC-Zinc blende. From the computed IR spectrum of RuC-Zinc blende at 50 GPa it is noted that the IR frequency increases with pressure. Using a semi-empirical model for hardness it is estimated that hardness of all three systems consistently increases with pressure. The hardness of RuC-Zinc blende increases towards the superhard regime up to the limiting pressure of its mechanical stability while that of RuC-Rhombohedral becomes 30 GPa at the pressure of 150 GPa.

  11. Skeletal muscle hemoglobin content measured by near-infrared spectroscopy during oscillatory venous pressure variation

    NASA Astrophysics Data System (ADS)

    Marcu, Laura; Maarek, Jean-Michel I.; Bembi, Atul; Howell, Sandra

    1995-04-01

    Changes in oxidized (HbO), reduced (Hbr), and total hemoglobin (Hbt) contents were monitored by near infrared spectroscopy in human forearm skeletal muscle during oscillatory variations of the effective venous pressure. Laser diode pulses (wavelength, 775, 810, 865, 904; duration, 60 ns) were directed to the muscle by means of an optic fiber bundle and detected with a sensing fiber positioned at 1.5 cm from the emitting bundle. Sinusoidal pressure waves (frequency, 1 and 2 cycles/min; amplitude, 10-15 mm Hg) generated by a piston pump were transmitted to a sphygmomanometer cuff placed on the arm, the mean cuff pressure (Pc) being 20, 40 and 60 mm Hg. Variations of HbO, Hbr and Hbt were computed from the optical signals and processed by Fourier analysis to characterize their amplitude and phase relative to the cuff mean pressure oscillations (Posc). Oscillations of HbO, Hbr, Hbt were observed for all mean cuff pressures, the amplitude of the variations being decreased with increasing Pc. For Pc equals 20 mm Hg, the oscillations of HbO and Hbt were nearly in phase with Posc whereas the oscillation of Hbr were out of phase with HbO and Posc. Increasing Pc resulted in an increase of the phase difference between HbO and Posc, Hbr remaining out of phase with Posc. These trends could be predicted with a lumped model of the forearm vasculature, suggesting that the technique could be used to asses mechanical characteristics of vascular beds.

  12. The magnetospheric response to 8-minute period strong-amplitude upstream pressure variations

    SciTech Connect

    Sibeck, D.G.; Lui, A.T.Y.; McEntire, R.W.; Potemra, T.A.; Takahashi, K. ); Baumjohann, W. ); Elphic, R.C. ); Fairfield, D.H. ); Fennell, J.F. ); Gail, W.B. ); Lanzerotti, L.J.; MacLennan, C.G. ); Lopez, R.E. ); Luehr, H. ); Rosenberg, T.J. )

    1989-03-01

    This paper documents a series of brief, strong ({Delta}p/p=1), dynamic pressure oscillations that occurred in the region upstream of the Earth's bow shock during a period of radial interplanetary magnetic field (IMF). The analyzed set of oscillations, which may be either intrinsic solar wind or bow shock-related phenomena, recur approximately every 8-10 min, and their magnetic field signatures occur nearly simultaneously over great distances transverse to the Earth-Sun line. The pressure oscillations appear to drive tailward-moving magnetopause surface wavelets. In turn, the surface wavelets can be identified as hydromagnetic waves with strong compressional components in the outer magnetosphere and as quasi-periodic variations in electron precipitation and high-latitude ground pulsations. The authors use observations by spacecraft in the outer dayside magnetosphere to predict geosynchronous and subsolar magnetic field strengths, the location of the subsolar magnetopause, the solar wind dynamic pressure, and variations in the energetic magnetospheric ion flux.

  13. Pulse pressure variation does not reflect stroke volume variation in mechanically ventilated rats with lipopolysaccharide-induced pneumonia.

    PubMed

    Cherpanath, Thomas G V; Smeding, Lonneke; Lagrand, Wim K; Hirsch, Alexander; Schultz, Marcus J; Groeneveld, Johan A B

    2014-01-01

    1. The present study examined the relationship between centrally measured stroke volume variation (SVV) and peripherally derived pulse pressure variation (PPV) in the setting of increased total arterial compliance (CA rt ). 2. Ten male Wistar rats were anaesthetized, paralysed and mechanically ventilated before being randomized to receive intrapulmonary lipopolysaccharide (LPS) or no LPS. Pulse pressure (PP) was derived from the left carotid artery, whereas stroke volume (SV) was measured directly in the left ventricle. Values of SVV and PPV were calculated over three breaths. Balloon inflation of a catheter positioned in the inferior vena cava was used, for a maximum of 30 s, to decrease preload while the SVV and PPV measurements were repeated. Values of CA rt were calculated as SV/PP. 3. Intrapulmonary LPS increased CA rt and SV. Values of SVV and PPV increased in both LPS-treated and untreated rats during balloon inflation. There was a correlation between SVV and PPV in untreated rats before (r = 0.55; P = 0.005) and during (r = 0.69; P < 0.001) occlusion of the vena cava. There was no such correlation in LPS-treated rats either before (r = -0.08; P = 0.70) or during (r = 0.36; P = 0.08) vena cava occlusion. 4. In conclusion, under normovolaemic and hypovolaemic conditions, PPV does not reflect SVV during an increase in CA rt following LPS-induced pneumonia in mechanically ventilated rats. Our data caution against their interchangeability in human sepsis. PMID:24372424

  14. Relation between respiratory variations in pulse oximetry plethysmographic waveform amplitude and arterial pulse pressure in ventilated patients

    PubMed Central

    Cannesson, Maxime; Besnard, Cyril; Durand, Pierre G; Bohé, Julien; Jacques, Didier

    2005-01-01

    Introduction Respiratory variation in arterial pulse pressure is a reliable predictor of fluid responsiveness in mechanically ventilated patients with circulatory failure. The main limitation of this method is that it requires an invasive arterial catheter. Both arterial and pulse oximetry plethysmographic waveforms depend on stroke volume. We conducted a prospective study to evaluate the relationship between respiratory variation in arterial pulse pressure and respiratory variation in pulse oximetry plethysmographic (POP) waveform amplitude. Method This prospective clinical investigation was conducted in 22 mechanically ventilated patients. Respiratory variation in arterial pulse pressure and respiratory variation in POP waveform amplitude were recorded simultaneously in a beat-to-beat evaluation, and were compared using a Spearman correlation test and a Bland–Altman analysis. Results There was a strong correlation (r2 = 0.83; P < 0.001) and a good agreement (bias = 0.8 ± 3.5%) between respiratory variation in arterial pulse pressure and respiratory variation in POP waveform amplitude. A respiratory variation in POP waveform amplitude value above 15% allowed discrimination between patients with respiratory variation in arterial pulse pressure above 13% and those with variation of 13% or less (positive predictive value 100%). Conclusion Respiratory variation in arterial pulse pressure above 13% can be accurately predicted by a respiratory variation in POP waveform amplitude above 15%. This index has potential applications in patients who are not instrumented with an intra-arterial catheter. PMID:16277719

  15. Implications of Dynamic Pressure Transducer Mounting Variations on Measurements in Pyrotechnic Test Apparatus

    NASA Technical Reports Server (NTRS)

    Dibbern, Andreas; Crisafulli, Jeffrey; Hagopia, Michael; McDougle, Stephen H.; Saulsberry, Regor L.

    2009-01-01

    Accurate dynamic pressure measurements are often difficult to make within small pyrotechnic devices, and transducer mounting difficulties can cause data anomalies that lead to erroneous conclusions. Delayed initial pressure response followed by data ringing has been observed when using miniaturized pressure transducer mounting adapters required to interface transducers to small test chambers. This delayed pressure response and ringing, combined with a high data acquisition rate, has complicated data analysis. This paper compares the output signal characteristics from different pressure transducer mounting options, where the passage distance from the transducer face to the pyrotechnic chamber is varied in length and diameter. By analyzing the data and understating the associated system dynamics, a more realistic understanding of the actual dynamic pressure variations is achieved. Three pressure transducer mounting configurations (elongated, standard, and face/flush mount) were simultaneously tested using NASA standard initiators in closed volume pressure bombs. This paper also presents results of these pressure transducer mounting configurations as a result of a larger NASA Engineering and Safety Center pyrovalve test project. Results from these tests indicate the improved performance of using face/flush mounted pressure transducers in this application. This type of mounting improved initial pressure measurement response time by approximately 19 s over standard adapter mounting, eliminating most of the lag time; provided a near step-function type initial pressure increase; and greatly reduced data ringing in high data acquisition rate systems. The paper goes on to discuss other issues associated with the firing and instrumentation that are important for the tester to understand.

  16. Variation in predator species abundance can cause variable selection pressure on warning signaling prey

    PubMed Central

    Valkonen, Janne K; Nokelainen, Ossi; Niskanen, Martti; Kilpimaa, Janne; Björklund, Mats; Mappes, Johanna

    2012-01-01

    Predation pressure is expected to drive visual warning signals to evolve toward conspicuousness. However, coloration of defended species varies tremendously and can at certain instances be considered as more camouflaged rather than conspicuous. Recent theoretical studies suggest that the variation in signal conspicuousness can be caused by variation (within or between species) in predators' willingness to attack defended prey or by the broadness of the predators' signal generalization. If some of the predator species are capable of coping with the secondary defenses of their prey, selection can favor reduced prey signal conspicuousness via reduced detectability or recognition. In this study, we combine data collected during three large-scale field experiments to assess whether variation in avian predator species (red kite, black kite, common buzzard, short-toed eagle, and booted eagle) affects the predation pressure on warningly and non-warningly colored artificial snakes. Predation pressure varied among locations and interestingly, if common buzzards were abundant, there were disadvantages to snakes possessing warning signaling. Our results indicate that predator community can have important consequences on the evolution of warning signals. Predators that ignore the warning signal and defense can be the key for the maintenance of variation in warning signal architecture and maintenance of inconspicuous signaling. PMID:22957197

  17. Variation in predator species abundance can cause variable selection pressure on warning signaling prey.

    PubMed

    Valkonen, Janne K; Nokelainen, Ossi; Niskanen, Martti; Kilpimaa, Janne; Björklund, Mats; Mappes, Johanna

    2012-08-01

    Predation pressure is expected to drive visual warning signals to evolve toward conspicuousness. However, coloration of defended species varies tremendously and can at certain instances be considered as more camouflaged rather than conspicuous. Recent theoretical studies suggest that the variation in signal conspicuousness can be caused by variation (within or between species) in predators' willingness to attack defended prey or by the broadness of the predators' signal generalization. If some of the predator species are capable of coping with the secondary defenses of their prey, selection can favor reduced prey signal conspicuousness via reduced detectability or recognition. In this study, we combine data collected during three large-scale field experiments to assess whether variation in avian predator species (red kite, black kite, common buzzard, short-toed eagle, and booted eagle) affects the predation pressure on warningly and non-warningly colored artificial snakes. Predation pressure varied among locations and interestingly, if common buzzards were abundant, there were disadvantages to snakes possessing warning signaling. Our results indicate that predator community can have important consequences on the evolution of warning signals. Predators that ignore the warning signal and defense can be the key for the maintenance of variation in warning signal architecture and maintenance of inconspicuous signaling. PMID:22957197

  18. Geographic variation of melanisation patterns in a hornet species: genetic differences, climatic pressures or aposematic constraints?

    PubMed

    Perrard, Adrien; Arca, Mariangela; Rome, Quentin; Muller, Franck; Tan, Jiangli; Bista, Sanjaya; Nugroho, Hari; Baudoin, Raymond; Baylac, Michel; Silvain, Jean-François; Carpenter, James M; Villemant, Claire

    2014-01-01

    Coloration of stinging insects is often based on contrasted patterns of light and black pigmentations as a warning signal to predators. However, in many social wasp species, geographic variation drastically modifies this signal through melanic polymorphism potentially driven by different selective pressures. To date, surprisingly little is known about the geographic variation of coloration of social wasps in relation to aposematism and melanism and to genetic and developmental constraints. The main objectives of this study are to improve the description of the colour variation within a social wasp species and to determine which factors are driving this variation. Therefore, we explored the evolutionary history of a polymorphic hornet, Vespa velutina Lepeletier, 1836, using mitochondrial and microsatellite markers, and we analysed its melanic variation using a colour space based on a description of body parts coloration. We found two main lineages within the species and confirmed the previous synonymy of V. auraria Smith, 1852, under V. velutina, differing only by the coloration. We also found that the melanic variation of most body parts was positively correlated, with some segments forming potential colour modules. Finally, we showed that the variation of coloration between populations was not related to their molecular, geographic or climatic differences. Our observations suggest that the coloration patterns of hornets and their geographic variations are determined by genes with an influence of developmental constraints. Our results also highlight that Vespa velutina populations have experienced several convergent evolutions of the coloration, more likely influenced by constraints on aposematism and Müllerian mimicry than by abiotic pressures on melanism. PMID:24740142

  19. Geographic Variation of Melanisation Patterns in a Hornet Species: Genetic Differences, Climatic Pressures or Aposematic Constraints?

    PubMed Central

    Perrard, Adrien; Arca, Mariangela; Rome, Quentin; Muller, Franck; Tan, Jiangli; Bista, Sanjaya; Nugroho, Hari; Baudoin, Raymond; Baylac, Michel; Silvain, Jean-François; Carpenter, James M.; Villemant, Claire

    2014-01-01

    Coloration of stinging insects is often based on contrasted patterns of light and black pigmentations as a warning signal to predators. However, in many social wasp species, geographic variation drastically modifies this signal through melanic polymorphism potentially driven by different selective pressures. To date, surprisingly little is known about the geographic variation of coloration of social wasps in relation to aposematism and melanism and to genetic and developmental constraints. The main objectives of this study are to improve the description of the colour variation within a social wasp species and to determine which factors are driving this variation. Therefore, we explored the evolutionary history of a polymorphic hornet, Vespa velutina Lepeletier, 1836, using mitochondrial and microsatellite markers, and we analysed its melanic variation using a colour space based on a description of body parts coloration. We found two main lineages within the species and confirmed the previous synonymy of V. auraria Smith, 1852, under V. velutina, differing only by the coloration. We also found that the melanic variation of most body parts was positively correlated, with some segments forming potential colour modules. Finally, we showed that the variation of coloration between populations was not related to their molecular, geographic or climatic differences. Our observations suggest that the coloration patterns of hornets and their geographic variations are determined by genes with an influence of developmental constraints. Our results also highlight that Vespa velutina populations have experienced several convergent evolutions of the coloration, more likely influenced by constraints on aposematism and Müllerian mimicry than by abiotic pressures on melanism. PMID:24740142

  20. Responses of Venus Ionosphere and Induced Magnetosphere to Solar Wind Pressure Variations

    NASA Astrophysics Data System (ADS)

    Ma, Yingjuan; Toth, Gabor; Nagy, Andrew F.; Russell, Christopher T.

    2016-04-01

    Often regarded as the Earth's 'sister planet', Venus has similar size and mass as Earth. But it is also remarkably different from Earth in many respects. Even though we have some basic knowledge of the solar wind interaction with Venus based on spacecraft observations, little is known about how the interaction and the resulting plasma escape rates vary in response to solar wind variations due to the lack of coordinated observations of both upstream solar wind conditions and simultaneous plasma properties in the Venus ionosphere. Furthermore, recent observations suggest that plasma escape rates are significantly enhanced during stormy space weather in response to solar wind pressure pulses (Edberg et al., 2011). Thus it is important to understand the plasma interaction under varying solar wind conditions. In this study, we use a sophisticated multi-species MHD model that has been recently developed for Venus (Ma et al., 2013) to characterize the responses of the ionosphere and the induced magnetosphere of Venus to a typical variation of the solar wind: dynamic pressure change. We will examine the response of the ionosphere and the induced magnetosphere to both pressure enhancements and decreases. We will quantify the total plasma escape-rate change in response to such variations and to identify the underlying driver for changes in escape rate. We will also quantify the time scale of the Venus ionosphere and induced magnetosphere in responding to the pressure change of the external solar wind driver.

  1. Fourier analysis of electrical impedance variations in urinary bladder during changes of intravesical pressure

    NASA Astrophysics Data System (ADS)

    Sivkov, A. V.; Mudraya, I. S.; Revenko, S. V.; Ibragimov, A. R.; Nesterov, A. V.; Gavrilov, I. Yu; Kirpatovsky, V. I.; Stranadko, M. V.

    2010-04-01

    Original hardware and software system was used to record and analyze the variations of electrical impedance of the urinary bladder in narcotized rats (n=7) at rest, during instillation of physiological saline into the bladder resulted in elevation of intravesical pressure, and during subsequent urination accompanied by intravesical pressure release. Fourier analysis of impedance variations revealed three periodic components with the frequencies of heartbeat, respiration, and the Mayer wave (~0.1 Hz). In resting bladder, the amplitude of Mayer and respiratory spectrum peaks were high, and they increased to a different extent during physiological elevation of intravesical pressure, while a small cardiac peak did not changed significantly and tended to decrease at high intravesical pressure. Urination released intravesical pressure and restored all the peaks to the resting level. It is hypothesized that Mayer and respiratory bioimpedance oscillations of urinary bladder are neural in origin, while the cardiac peak is mainly determined by hydrodynamic arterial pulsations. The novel method can assess vesical circulation and its neural control at various phases of bladder activity.

  2. Resistivity Variation due to CO2 Migration in Different Temperature and Pressure Conditions

    NASA Astrophysics Data System (ADS)

    Nakatsuka, Y.; Onishi, K.; Yamada, Y.; Matsuoka, T.; Xue, Z.

    2007-12-01

    CO2 geological sequestration is one of the effective approaches solving the global warming problem. Captured CO2 is injected to the deep aquifers or depleted oil and gas fields. Injected CO2 migrates thorough the reservoir rock, however, the details behavior of injected CO2 under the ground at super critical phase is not yet fully understood. Migration of injected CO2 will change by the condition of the injected reservoir such as the temperature and pressure. Also density and permeability of the rock may be changed due to temperature or pressure variations. These changes control the migration behavior of injected CO2. In this study, experiments of resistivity measurements were conducted to detect the migration difference of CO2 in different temperature and pressure conditions by using sandstone core samples. Core sample was taken from Berea sandstone and processed to 5cm diameter and 12cm length. For the resistivity measurement, impression electrode was set on the both end and the measurement electrode of ring condition was set on the side of the rock sample. We stetted the core sample in the pressure vessel and recreated the condition of underground reservoir which is high pressure and high temperature. We injected supercritical CO2 in different pressure and temperature for each experiment. Pressure was changed in range of 8 to 11MPa and temperature was changed in range of 35° to 45°. This means that all the experiments were conducted in supercritical phase. From the measured resistivity variation, we verified the migration of CO2 and compared the migration behavior of CO2 in different conditions.

  3. Anxiety coping style and daily blood pressure variation of female nurses.

    PubMed

    Broege; James; Peters

    1997-08-01

    OBJECTIVE: To examine how the style of coping with anxiety influences ambulatory blood pressures measured in work and home environments for 63 women aged 34 +/- 8 years employed as nurses. METHODS: Awake ambulatory blood pressures measured at work (n = 38 readings) and at home (n =7 readings) were compared among nurses who had been classified as belonging to four anxiety-coping-style groups: low anxious repressive (n = 18 work, n = 16 home), high anxious defensive (n = 4 work, n = 4 home) true low anxious (n = 21 work, n = 20 home) and true high anxious (n = 19 work, n = 18 home). The four anxiety-coping-style groups were determined by cross-classifying the women upon the basis of their scores on the Marlowe-Crowne Social Desirability Scale (cutoff at 18) and the Taylor Manifest Anxiety Scale (cutoff at 14). RESULTS: Average systolic blood pressures at work and at home among nurses with a low anxious repressive coping style were significantly lower than were those of nurses with a high anxious defensive coping style (P < 0.05) and a true low anxious coping style ( P < 0.025). Nurses with a low anxious repressive coping style also had lower diastolic blood pressures at work than did those with a high anxious defensive coping style ( P < 0.05) and lower diastolic blood pressures at home than did those with a true anxious coping style ( P < 0.01). Finally, subjects with a high anxious defensive coping style had significantly higher systolic blood pressures at work and at home (P < 0.05) and higher diastolic blood pressures at work than did nurses with a true high anxious coping style. The effects of the style of coping on the variation of work and home blood pressures were independent of several covariates including weight, perceived stress, smoking, alcohol, postural variation, and number of children. The univariate scales of Social Desirability and Anxiety also had no effect on the variability of the blood pressure. CONCLUSION: Among employed women, the extent of

  4. Upstream pressure variations associated with the bow shock and their effects on the magnetosphere

    NASA Technical Reports Server (NTRS)

    Fairfield, D. H.; Baumjohann, W.; Paschmann, G.; Luehr, H.; Sibeck, D. G.

    1990-01-01

    The AMPTE IRM solar wind data are analyzed to determine the relationship between upstream pressure fluctuations and magnetospheric perturbations. It is argued that the upstream pressure variations are not inherent in the solar wind but rather are associated with the bow shock. This conclusion follows from the fact that the upstream field strength and density associated with perturbations are highly correlated with each other, while they tend to be anticorrelated in the undisturbed solar wind, and that the upstream perturbations occur within the foreshock or at its boundary. The results imply a mode of interaction between the solar wind upstream and the magnetosphere whereby density changes produced in the foreshock subsequently convect through the bow shock and impinge on the magnetosphere. Upstream pressure perturbations should create significant effects on the magnetopause and at the foot of nearby field lines that lead to the polar cusp ionosphere.

  5. Cortical representation of tympanic membrane movements due to pressure variation: an fMRI study.

    PubMed

    Job, Agnès; Paucod, Jean-Charles; O'Beirne, Greg A; Delon-Martin, Chantal

    2011-05-01

    Middle ear sensory information has never been localized in the homunculus of the somatosensory cortex (S1). We investigated the somatosensory representation of the middle ear in 15 normal hearing subjects. We applied small air pressure variations to the tympanic membrane while performing a 3T-fMRI study. Unilateral stimulations of the right ear triggered bilateral activations in the caudal part of the postcentral gyrus in Brodmann area 43 (BA 43) and in the auditory associative areas 42 (BA 42) and 22 (BA 22). BA 43 has been found to be involved in activities accompanying oral intake and could be more largely involved in pressure activities in the oropharynx area. The tympanic membrane is indirectly related to the pharynx area through the action of tensor tympani, which is a Eustachian tube muscle. The Eustachian tube muscles have a role in pressure equalization in the middle ear and also have a role in the pharyngeal phase of swallowing. Activation of BA 42 and BA 22 could reflect activations associated with the bilateral acoustic reflex triggered prior to self-vocalization to adjust air pressure in the oropharynx during speech. We propose that BA 43, 42, and 22 are the cortical areas associated with middle ear function. We did not find representation of tympanic membrane movements due to pressure in S1, but its representation in the postcentral gyrus in BA 43 seems to suggest that at least part of this area conveys pure somatosensory information. PMID:21484948

  6. A variational model of disjoining pressure: Liquid film on a nonplanar surface

    SciTech Connect

    Silin, D.; Virnovsky, G.

    2009-06-01

    Variational methods have been successfully used in modelling thin liquid films in numerous theoretical studies of wettability. In this paper, the variational model of the disjoining pressure is extended to the general case of a two-dimensional solid surface. The Helmgoltz free energy functional depends both on the disjoining pressure isotherm and the shape of the solid surface. The augmented Young-Laplace equation (AYLE) is a nonlinear second-order partial differential equation. A number of solutions describing wetting films on spherical grains have been obtained. In the case of cylindrical films, the phase portrait technique describes the entire variety of mathematically feasible solutions. It turns out that a periodic solution, which would describe wave-like wetting films, does not satisfy the Jacobi's condition of the classical calculus of variations. Therefore, such a solution is nonphysical. The roughness of the solid surface significantly affects liquid film stability. AYLE solutions suggest that film rupture is more likely at a location where the pore-wall surface is most exposed into the pore space and the curvature is positive.

  7. Load variation effects on the pressure fluctuations exerted on a Kaplan turbine runner

    NASA Astrophysics Data System (ADS)

    Amiri, K.; Mulu, B.; Raisee, M.; Cervantes, M. J.

    2014-03-01

    Introduction of intermittent electricity production systems like wind power and solar systems to electricity market together with the consumption-based electricity production resulted in numerous start/stops, load variations and off-design operation of water turbines. The hydropower systems suffer from the varying loads exerted on the stationary and rotating parts of the turbines during load variations which they are not designed for. On the other hand, investigations on part load operation of single regulated turbines, i.e., Francis and propeller, proved the formation of rotating vortex rope (RVR) in the draft tube. The RVR induces oscillating flow both in plunging and rotating modes which results in oscillating force with two different frequencies on the runner blades, bearings and other rotating parts of the turbine. The purpose of this study is to investigate the effect of transient operations on the pressure fluctuations on the runner and mechanism of the RVR formation/mitigation. Draft tube and runner blades of the Porjus U9 model, a Kaplan turbine, were equipped with pressure sensors. The model was run in off-cam mode during different load variation conditions to check the runner performance under unsteady condition. The results showed that the transients between the best efficiency point and the high load happens in a smooth way while transitions to/from the part load, where rotating vortex rope (RVR) forms in the draft tube induces high level of fluctuations with two frequencies on the runner; plunging and rotating mode of the RVR.

  8. Dominance of toroidal oscillations in dawn/dusk sectors: A consequence of solar wind pressure variation

    NASA Astrophysics Data System (ADS)

    Sinha, A. K.; Rajaram, R.

    2003-02-01

    The pressure variations in the solar wind produce the oscillations in surface currents at the magnetopause boundary in order to nullify the pressure imbalance. These currents introduce compressional variations in the magnetic field within the magnetosphere. The response of transverse field line oscillations to such changes in the magnetic field has been brought out in perfectly reflecting ionospheric conditions. The analysis clearly shows that the fundamental toroidal modes are dominant in the dawn and the dusk sectors as revealed by the statistical studies of pulsations observed by the satellite AMPTE/CCE (Anderson et al., 1990). It is traditionally believed that such oscillations are mainly driven by Kelvin-Helmholtz (K-H) instability (Anderson et al., 1990). Our analysis shows that the dominance of fundamental toroidal modes in the dawn and dusk sectors can also be explained in terms of response to impressed pressure impulses without invoking K-H instability. The analysis also shows that poloidal modes do not exhibit any longitudinal structures. These results are consistent with the observations (Anderson et al., 1990).

  9. The contribution of pleiotropy to blood pressure and body-mass index variation: the Gubbio Study.

    PubMed Central

    Schork, N. J.; Weder, A. B.; Trevisan, M.; Laurenzi, M.

    1994-01-01

    Blood pressure (BP), body-mass index (BMI), and quantitative phenotypes thought to influence BP (e.g., lithium-sodium countertransport activity) were studied in 2,184 households comprising 5,376 people in Gubbio, Italy. Variance-components models were used to partition the variation of these phenotypes into components characterizing the effects of age-related, measured environmental, additive genetic, pleiotropic, unmeasured shared-household, and individual-specific (or random) factors. The goal of the investigation was to estimate the contribution of pleiotropy to variation in BP and BMI in population-based samples. Although our results suggest that numerous significant bivariate genetic correlations exist between BP and some of the traits investigated, they ultimately lead us to reject a prominent role for any individual bivariate pleiotropic system influencing the natural variation of BP. However, because we found evidence that many traits enter into small-impact pleiotropic relationships with BP, we cannot rule out the possibility that pleiotropic genes, when considered collectively, may contribute to BP variation at the population level. Similar results were obtained when BMI was taken as the primary variable of interest. We argue that the small but significant portion of BP variation explained by individual genes displaying bivariate pleiotropic effects is intuitive, in light of the relatively low heritabilities associated with quantitative cardiovascular phenotypes and the low phenotypic correlations between BP, BMI, and many other physiologically linked measures of cardiovascular function. Our results not only bear directly on both the nature of the multifactorial determinants of BP and the maintenance of BP variation in the population at large, but also emphasize the utility of variance-components models in epidemiologic and population genetics research. We discuss the implications of our results for genetic epidemiologists and medical researchers studying

  10. A controlled variation scheme for convection treatment in pressure-based algorithm

    NASA Technical Reports Server (NTRS)

    Shyy, Wei; Thakur, Siddharth; Tucker, Kevin

    1993-01-01

    Convection effect and source terms are two primary sources of difficulties in computing turbulent reacting flows typically encountered in propulsion devices. The present work intends to elucidate the individual as well as the collective roles of convection and source terms in the fluid flow equations, and to devise appropriate treatments and implementations to improve our current capability of predicting such flows. A controlled variation scheme (CVS) has been under development in the context of a pressure-based algorithm, which has the characteristics of adaptively regulating the amount of numerical diffusivity, relative to central difference scheme, according to the variation in local flow field. Both the basic concepts and a pragmatic assessment will be presented to highlight the status of this work.

  11. Colour variation in cichlid fish: Developmental mechanisms, selective pressures and evolutionary consequences☆

    PubMed Central

    Maan, Martine E.; Sefc, Kristina M.

    2013-01-01

    Cichlid fishes constitute one of the most species-rich families of vertebrates. In addition to complex social behaviour and morphological versatility, they are characterised by extensive diversity in colouration, both within and between species. Here, we review the cellular and molecular mechanisms underlying colour variation in this group and the selective pressures responsible for the observed variation. We specifically address the evidence for the hypothesis that divergence in colouration is associated with the evolution of reproductive isolation between lineages. While we conclude that cichlid colours are excellent models for understanding the role of animal communication in species divergence, we also identify taxonomic and methodological biases in the current research effort. We suggest that the integration of genomic approaches with ecological and behavioural studies, across the entire cichlid family and beyond it, will contribute to the utility of the cichlid model system for understanding the evolution of biological diversity. PMID:23665150

  12. Atmospheric pressure, density, temperature and wind variations between 50 and 200 km

    NASA Technical Reports Server (NTRS)

    Justus, C. G.; Woodrum, A.

    1972-01-01

    Data on atmospheric pressure, density, temperature and winds between 50 and 200 km were collected from sources including Meteorological Rocket Network data, ROBIN falling sphere data, grenade release and pitot tube data, meteor winds, chemical release winds, satellite data, and others. These data were analyzed by a daily difference method and results on the distribution statistics, magnitude, and spatial structure of the irregular atmospheric variations are presented. Time structures of the irregular variations were determined by the analysis of residuals from harmonic analysis of time series data. The observed height variations of irregular winds and densities are found to be in accord with a theoretical relation between these two quantities. The latitude variations (at 50 - 60 km height) show an increasing trend with latitude. A possible explanation of the unusually large irregular wind magnitudes of the White Sands MRN data is given in terms of mountain wave generation by the Sierra Nevada range about 1000 km west of White Sands. An analytical method is developed which, based on an analogy of the irregular motion field with axisymmetric turbulence, allows measured or model correlation or structure functions to be used to evaluate the effective frequency spectra of scalar and vector quantities of a spacecraft moving at any speed and at any trajectory elevation angle.

  13. Stochastic Modelling and Estimation for Cyclic Pressure Variations in Spark Ignition Engines

    NASA Astrophysics Data System (ADS)

    Roberts, J. B.; Peyton Jones, J. C.; Landsborough, K. J.

    2001-03-01

    A new method of fitting linearised, parametric stochastic models of cycle-by-cycle variations of pressure, during the combustion region of a spark ignition petrol engine, is described. The technique is based on stochastically fitting the combustion models to the covariance function of the measured pressure fluctuations, obtained by averaging over the entire ensemble of measured cycles. Comparisons, for two specific combustion models, with corresponding results obtained by deterministic fitting on a cycle-by-cycle basis, show that the new method gives a similar degree of fit, but with much improved computational efficiency. It is also demonstrated that the degree of fit to the data can be further improved by modelling the residual error between the data and the combustion models in terms of Chebyshev polynomials: the parameters in these polynomials may be determined by stochastic fitting. The technique has wider applications in the condition monitoring of rotating machinery.

  14. Variations in nanomechanical properties of back-end Zr-2.5Nb pressure tube material

    NASA Astrophysics Data System (ADS)

    Gallaugher, Matthew; Peykov, Daniel; Brodusch, Nicolas; Chromik, Richard R.; Rodrigue, Lisa; Trudeau, Michel L.; Gauvin, Raynald

    2013-11-01

    The Zr-2.5Nb pressure tube alloy used in Canada Deuterium Uranium (CANDU) nuclear reactors consists of a dual-phase microstructure produced by a multi-step manufacturing process. The metallurgical characteristics of the pressure tubes influence their in-reactor behavior, especially with respect to reactor life-limiting properties such as diametral creep. In order to predict the in-reactor behavior of pressure tubes, a greater understanding of the influence of tube-to-tube variations in metallurgical factors such as texture, grain size, and β-phase percentage would be greatly beneficial. In this paper, a testing method combining high temperature nanoindentation with subsequent electron channeling contrast imaging (ECCI) in the scanning electron microscope (SEM) is presented to compare two back end pressure tube off-cuts. Nanoindentation was used to measure local mechanical properties such as hardness, modulus, and strain rate sensitivity. Post-examination of residual indents with ECCI allowed for the correlation of microstructural characteristics to nanomechanical properties. A difference in hardness was observed between the two tubes in the axial normal plane, which was correlated to differences in β-phase area percentage and/or morphology.

  15. Density variations in the thickened crust as a function of pressure, temperature, and composition

    NASA Astrophysics Data System (ADS)

    Semprich, Julia; Simon, Nina S. C.; Podladchikov, Yuri Yu.

    2010-10-01

    Constraints on density as a function of pressure, temperature, and composition are crucial to understand isostatic movements during geodynamic processes. Here, we provide a systematic series of density diagrams extracted from thermodynamic calculations for a variety of crustal compositions within a wide P- T range. We quantify systematic density changes in collisional settings for relevant compositional variations and attempt to simplify the density-composition relationships. Rock densities depend strongly on pressure, temperature, and composition. Densities at some selected pressure-temperature conditions increase linearly with increasing Al2O3 as well as MgO/FeO contents in pelitic rocks. Al- and Fe-rich pelites yield the highest densities, which is mostly due to the formation of garnet but also depends on other minerals and changes of reactions. The effect of loading on densities is investigated, and we show that for deep burial, a meta-pelite rich in Fe and Mg yields much larger density changes than a dry basalt and that the burial of such a rock with a composition close to typical lower crust may result in significant negative buoyancy. Metamorphism of hydrous lower crust due to pressurization and heating thus leads to densification of thickened lower crust, while heating of dry crust leads to a decrease in density. Hence, water-loaded isostatic subsidence due to metamorphism of water-saturated lower crust is substantial and increases with the thickness and depth of the reacting layer, while dry compositions show much less or only transient densification and subsidence. The density change due to thermal expansion, an extensively used concept in geodynamic models, predicts uplift under the same P- T conditions and is an order of magnitude smaller than the density variation calculated from petrologically consistent diagrams.

  16. Cross-cultural variation in blood pressure: a quantitative analysis of the relationships of blood pressure to cultural characteristics, salt consumption and body weight.

    PubMed

    Waldron, I; Nowotarski, M; Freimer, M; Henry, J P; Post, N; Witten, C

    1982-01-01

    This study has analyzed the relationships of cross-cultural variation in blood pressure to cultural characteristics, salt consumption and body weight. The data used were blood pressures for adults in 84 groups, ratings of cultural characteristics (based on anthropological data and made by raters who had no knowledge of the blood pressure data) and, where available, salt consumption and body mass index (weight/height2). Blood pressures were higher and the slopes of blood pressure with age were greater in groups which had greater involvement in a money economy, more economic competition, more contact with people of different culture or beliefs, and more unfulfilled aspirations for a return to traditional beliefs and values. Blood pressures were also higher in groups for which the predominant family type was a nuclear or father-absent family, as opposed to an extended family. For Negroes, groups who were descended from slaves had higher blood pressures than other groups. The correlations between blood pressures and involvement in a money economy were substantial and significant even after controlling for level of salt consumption and, for men, also after controlling for body mass index. For men there were also significant partial correlations between blood pressure and salt consumption, controlling for type of economy. For women there were significant partial correlations between blood pressure and body mass index, controlling for type of economy. In conclusion, cross-cultural variation in blood pressure appears to be due to multiple factors. One contributory factor appears to be psychosocial stress due to cultural disruption, including the disruption of cooperative relationships and traditional cultural patterns which frequently occurs during economic modernization. In addition, both the protective effects of very low salt consumption in some groups and differences in body weight appear to contribute to cross-cultural variation in blood pressure. PMID:7079796

  17. Noise in pressure transducer readings produced by variations in solar radiation

    USGS Publications Warehouse

    Cain, S. F., III; Davis, G.A.; Loheide, S.P., II; Butler, J.J., Jr.

    2004-01-01

    Variations in solar radiation can produce noise in readings from gauge pressure transducers when the transducer cable is exposed to direct sunlight. This noise is a result of insolation-induced heating and cooling of the air column in the vent tube of the transducer cable. A controlled experiment was performed to assess the impact of variations in solar radiation on transducer readings. This experiment demonstrated that insolation-induced fluctuations in apparent pressure head can be as large as 0.03 m. The magnitude of these fluctuations is dependent on cable color, the diameter of the vent tube, and the length of the transducer cable. The most effective means of minimizing insolation-induced noise is to use integrated transducer-data logger units that fit within a well. Failure to address this source of noise can introduce considerable uncertainty into analyses of hydraulic tests when the head change is relatively small, as is often the case for tests in highly permeable aquifers or for tests using distant observation wells.

  18. Noise in pressure transducer readings produced by variations in solar radiation.

    PubMed

    Cain, Samuel F; Davis, Gregory A; Loheide, Steven P; Butler, James J

    2004-01-01

    Variations in solar radiation can produce noise in readings from gauge pressure transducers when the transducer cable is exposed to direct sunlight. This noise is a result of insolation-induced heating and cooling of the air column in the vent tube of the transducer cable. A controlled experiment was performed to assess the impact of variations in solar radiation on transducer readings. This experiment demonstrated that insolation-induced fluctuations in apparent pressure head can be as large as 0.03 m. The magnitude of these fluctuations is dependent on cable color, the diameter of the vent tube, and the length of the transducer cable. The most effective means of minimizing insolation-induced noise is to use integrated transducer-data logger units that fit within a well. Failure to address this source of noise can introduce considerable uncertainty into analyses of hydraulic tests when the head change is relatively small, as is often the case for tests in highly permeable aquifers or for tests using distant observation wells. PMID:15584307

  19. Polymorphisms in the WNK1 Gene Are Associated with Blood Pressure Variation and Urinary Potassium Excretion

    PubMed Central

    Newhouse, Stephen; Farrall, Martin; Wallace, Chris; Hoti, Mimoza; Burke, Beverley; Howard, Philip; Onipinla, Abiodun; Lee, Kate; Shaw-Hawkins, Sue; Dobson, Richard; Brown, Morris; Samani, Nilesh J.; Dominiczak, Anna F.; Connell, John M.; Lathrop, G. Mark; Kooner, Jaspal; Chambers, John; Elliott, Paul; Clarke, Robert; Collins, Rory; Laan, Maris; Org, Elin; Juhanson, Peeter; Veldre, Gudrun; Viigimaa, Margus; Eyheramendy, Susana; Cappuccio, Francesco P.; Ji, Chen; Iacone, Roberto; Strazzullo, Pasquale; Kumari, Meena; Marmot, Michael; Brunner, Eric; Caulfield, Mark; Munroe, Patricia B.

    2009-01-01

    WNK1 - a serine/threonine kinase involved in electrolyte homeostasis and blood pressure (BP) control - is an excellent candidate gene for essential hypertension (EH). We and others have previously reported association between WNK1 and BP variation. Using tag SNPs (tSNPs) that capture 100% of common WNK1 variation in HapMap, we aimed to replicate our findings with BP and to test for association with phenotypes relating to WNK1 function in the British Genetics of Hypertension (BRIGHT) study case-control resource (1700 hypertensive cases and 1700 normotensive controls). We found multiple variants to be associated with systolic blood pressure, SBP (7/28 tSNPs min-p = 0.0005), diastolic blood pressure, DBP (7/28 tSNPs min-p = 0.002) and 24 hour urinary potassium excretion (10/28 tSNPs min-p = 0.0004). Associations with SBP and urine potassium remained significant after correction for multiple testing (p = 0.02 and p = 0.01 respectively). The major allele (A) of rs765250, located in intron 1, demonstrated the strongest evidence for association with SBP, effect size 3.14 mmHg (95%CI:1.23–4.9), DBP 1.9 mmHg (95%CI:0.7–3.2) and hypertension, odds ratio (OR: 1.3 [95%CI: 1.0–1.7]).We genotyped this variant in six independent populations (n = 14,451) and replicated the association between rs765250 and SBP in a meta-analysis (p = 7×10−3, combined with BRIGHT data-set p = 2×10−4, n = 17,851). The associations of WNK1 with DBP and EH were not confirmed. Haplotype analysis revealed striking associations with hypertension and BP variation (global permutation p<10−7). We identified several common haplotypes to be associated with increased BP and multiple low frequency haplotypes significantly associated with lower BP (>10 mmHg reduction) and risk for hypertension (OR<0.60). Our data indicates that multiple rare and common WNK1 variants contribute to BP variation and hypertension, and provide compelling evidence to initiate further

  20. Non-invasive continuous arterial pressure and pulse pressure variation measured with Nexfin(®) in patients following major upper abdominal surgery: a comparative study.

    PubMed

    de Wilde, R B P; de Wit, F; Geerts, B F; van Vliet, A L; Aarts, L P H J; Vuyk, J; Jansen, J R C

    2016-07-01

    We compared the accuracy and precision of the non-invasive Nexfin(®) device for determining systolic, diastolic, mean arterial pressure and pulse pressure variation, with arterial blood pressure values measured from a radial artery catheter in 19 patients following upper abdominal surgery. Measurements were taken at baseline and following fluid loading. Pooled data results of the arterial blood pressures showed no difference between the two measurement modalities. Bland-Altman analysis of pulse pressure variation showed significant differences between values obtained from the radial artery catheter and Nexfin finger cuff technology (mean (SD) 1.49 (2.09)%, p < 0.001, coefficient of variation 24%, limits of agreement -2.71% to 5.69%). The effect of volume expansion on pulse pressure variation was identical between methods (concordance correlation coefficient 0.848). We consider the Nexfin monitor system to be acceptable for use in patients after major upper abdominal surgery without major cardiovascular compromise or haemodynamic support. PMID:27291598

  1. Mediterranean sea level oscillations as a response to the atmospheric pressure variations, altimetric implications

    NASA Astrophysics Data System (ADS)

    Gomez-Enri, Jesus; Bruno Mejias, Miguel; Villares Duran, Pilar

    2004-02-01

    The real sea level response to atmospheric pressure variations is quantified and compared with the one deduced from the isostatic assumption, which is normally used to correct the effect of the atmospheric pressure oscillations in the ocean, the so-called Inverse Barometer Correction (IBC). We have analysed the first four years of ERS-2 altimetric records in the Mediterranean Sea. We obtained the regression coefficients at each geographical point of the satellite tracks and in the crossover track points, estimating the relation between the surface atmospheric pressure and the sea level anomalies. The geographical distribution of the regression coefficients obtained, demonstrates that there are important local deviations from the hypothetical value (-0.998 cm/bar), being more evident when we reduce the time sampling from 35 days to 10.5 days. We have obtained the variance associated to the inverse barometer correction, and the one obtained by using the individual regression coefficients obtained at each geographical position in both, collinear and crossover method. We observe a variance reduction of approximately 30% in the sea level anomalies series, when barometric corrections are applied, in the case of collinear track method, and around 15% when we use the crossover track method. We have also quantified the difference in the variance reduction of the sea level anomalies when the standard IBC and the atmospheric pressure correction (use of the regression coefficients estimated on each geographical position, instead of the isostatic value: -0.998 cm/mbar) are applied. We also observe a reduction of approximately 2% in the variance when the atmospheric correction is applied, instead of IBC (in both cases, CM and XM).

  2. Observational features of field line resonances excited by solar wind pressure variations on 4 September 1984

    NASA Technical Reports Server (NTRS)

    Warnecke, J.; Luehr, H.; Takahashi, K.

    1990-01-01

    The purpose of the study is to establish the most probable excitation mechanism of the magnetic storm occurred after an inverse sudden impulse on September 4, 1984. Geomagnetic pulsations in the Pc5-frequency range observed at magnetometer stations are evaluated. Attention is focused on two events of the enhanced activity: for the first one, conjugate observations on the ground are assessed and then compared with satellite-based observations on adjacent field lines; for the second event two hours later, data from an extended azimuthal range is employed. It is pointed out that the observations are consistent with the theory of filed-line resonance, and may be interpreted as excitations caused by pressure variations in the solar wind. Both magnetopause-surface waves and cavity resonances are excited; the cavity mode drives toroidal field-line oscillations at locations where its frequency matches the resonance frequency of the field lines.

  3. North Atlantic meridional overturning circulation variations from GRACE ocean bottom pressure anomalies

    NASA Astrophysics Data System (ADS)

    Landerer, Felix W.; Wiese, David N.; Bentel, Katrin; Boening, Carmen; Watkins, Michael M.

    2015-10-01

    Concerns about North Atlantic Meridional Overturning Circulation (NAMOC) changes imply the need for a continuous, large-scale observation capability to detect changes on interannual to decadal time scales. Here we present the first measurements of Lower North Atlantic Deep Water (LNADW) transport changes using only time-variable gravity observations from Gravity Recovery and Climate Experiment (GRACE) satellites from 2003 until now. Improved monthly gravity field retrievals allow the detection of North Atlantic interannual bottom pressure anomalies and LNADW transport estimates that are in good agreement with those from the Rapid Climate Change-Meridional Overturning Circulation and Heatflux Array (RAPID/MOCHA). Concurrent with the observed AMOC transport anomalies from late 2009 through early 2010, GRACE measured ocean bottom pressures changes in the 3000-5000 m deep western North Atlantic on the order of 20 mm-H2O (200 Pa), implying a southward volume transport anomaly in that layer of approximately -5.5 sverdrup. Our results highlight the efficacy of space gravimetry for observing AMOC variations to evaluate latitudinal coherency and long-term variability.

  4. [Baroreflex and blood pressure variations in borderline hypertension of the young adult].

    PubMed

    Chanudet, X; Chau, N P; Hoffman, O; Fassa, Y; Clément, R; Garcin, J M; Larroque, P

    1991-08-01

    Blood pressure (BP) variability depends on external and internal factors. Among these, arterial baroreflex play an important role. The matter of this study is to assess the relationship between these two parameters in borderline hypertension (BL). Twenty six BL male hypertensive were recruited for the study, all gave informed consent. Age: 21 +/- 2 years, height: 177 +/- 8 cm, weight: 77 +/- 14 kg. An ambulatory BP monitoring was performed in each one using a Diasys (Novacor) recorder. Measurements were obtained each 15 minutes for 24 hours. Mean, standard deviation and variation coefficient (VC) of BP and heart rate (HR) were computed for 24 hours, daytime (9a.m.-7 p.m.), nighttime (11 p.m.-7 a.m.). Baroreflex sensitivity (BRS) was determined as the ratio of HR variation on systolic BP variation recorded with a Finapres device from the fourth phase of a Valsalva manoeuvre. Mean systolic and diastolic BP values for 24 hours, daytime and nighttime are: 129 +/- 11/73 +/- 13, 137 +/- 14/76 +/- 15, 114 +/- 11/69 +/- 12 mmHg. VC are: 12 +/- 3/15 +/- 3, 9 +/- 3/13 +/- 3, 10 +/- 3/13 +/- 4%. HR values are: 73 +/- 10, 84 +/- 14, 58 +/- 7 b/min, VC are: 24 +/- 5, 17 +/- 4, 17 +/- 7%. Index for BRS = 1.76 +/- 0.65%. There is no correlation between BRS and systolic BP or HR. BRS is correlated to the inverse of systolic daytime BP VC: r = -0.556, p = 0.003. There is no correlation with other parameters. This study provides evidence for a link between BRS and daytime BP variability in borderline hypertension. PMID:1953260

  5. Hydromechanical Rock Mass Fatigue in Deep-Seated Landslides Accompanying Seasonal Variations in Pore Pressures

    NASA Astrophysics Data System (ADS)

    Preisig, Giona; Eberhardt, Erik; Smithyman, Megan; Preh, Alexander; Bonzanigo, Luca

    2016-06-01

    The episodic movement of deep-seated landslides is often governed by the presence of high pore pressures and reduced effective stresses along active shear surfaces. Pore pressures are subject to cyclic fluctuation under seasonal variations of groundwater recharge, resulting in an intermittent movement characterized by acceleration-deceleration phases. However, it is not always clear why certain acceleration phases reach alarming levels without a clear trigger (i.e., in the absence of an exceptional pore pressure event). This paper presents a conceptual framework linking hydromechanical cycling, progressive failure and fatigue to investigate and explain the episodic behavior of deep-seated landslides using the Campo Vallemaggia landslide in Switzerland as a case study. A combination of monitoring data and advanced numerical modeling is used. The principal processes forcing the slope into a critical disequilibrium state are analyzed as a function of rock mass damage and fatigue. Modeling results suggest that during periods of slope acceleration, the rock slope experiences localized fatigue and gradual weakening through slip along pre-existing natural fractures and yield of critically stressed intact rock bridges. At certain intervals, pockets of critically weakened rock may produce a period of enhanced slope movement in response to a small pore pressure increase similar to those routinely experienced each year. Accordingly, the distribution and connectivity of pre-existing permeable planes of weakness play a central role. These structures are often related to the rock mass's tectonic history or initiate (and dilate) in response to stress changes that disturb the entire slope, such as glacial unloading or seismic loading via large earthquakes. The latter is discussed in detail in a companion paper to this (Gischig et al., Rock Mech Rock Eng, 2015). The results and framework presented further demonstrate that episodic movement and progressive failure of deep

  6. Vertical laryngeal position and oral pressure variations during resonance tube phonation in water and in air. A pilot study.

    PubMed

    Wistbacka, Greta; Sundberg, Johan; Simberg, Susanna

    2016-10-01

    Resonance tube phonation in water (RTPW) is commonly used in voice therapy, particularly in Finland and Sweden. The method is believed to induce a lowering of the vertical laryngeal position (VLP) in phonation as well as variations of the oral pressure, possibly inducing a massage effect. This pilot study presents an attempt to measure VLP and oral pressure in two subjects during RTPW and during phonation with the free tube end in air. VLP is recorded by means of a dual-channel electroglottograph. RTPW was found to lower VLP in the subjects, while it increased during phonation with the tube end in air. RTPW caused an oral pressure modulation with a bubble frequency of 14-22 Hz, depending mainly on the depth of the tube end under the water surface. The results indicate that RTPW lowers the VLP instantly and creates oral pressure variations. PMID:26033381

  7. Possible origins of time variability in Jupiter's outer magnetosphere. I - Variations in solar wind dynamic pressure. II - Variations in solar wind magnetic field

    NASA Technical Reports Server (NTRS)

    Coroniti, F. V.; Kennel, C. F.

    1977-01-01

    Attention is given to the effect of changes in the dynamic pressure of the solar wind on the structure of a centrifugally driven planetary wind from Jupiter. It is suggested that dynamic pressure variations can induce a transition between a super-Alfvenic wind and a sub-Alfvenic wind breeze on Jupiter's dayside. This could possibly account for the observed large-scale changes in the structure of Jupiter's outer magnetosphere. An attempt is then made to conceptually merge planetary wind models of Jupiter's outer magnetosphere with reconnection models of Jupiter's outer magnetosphere.

  8. CO2 Exsolution from CO2 Saturated Water: Core-Scale Experiments and Focus on Impacts of Pressure Variations.

    PubMed

    Xu, Ruina; Li, Rong; Ma, Jin; Jiang, Peixue

    2015-12-15

    For CO2 sequestration and utilization in the shallow reservoirs, reservoir pressure changes are due to the injection rate changing, a leakage event, and brine withdrawal for reservoir pressure balance. The amounts of exsolved CO2 which are influenced by the pressure reduction and the subsequent secondary imbibition process have a significant effect on the stability and capacity of CO2 sequestration and utilization. In this study, exsolution behavior of the CO2 has been studied experimentally using a core flooding system in combination with NMR/MRI equipment. Three series of pressure variation profiles, including depletion followed by imbibitions without or with repressurization and repetitive depletion and repressurization/imbibition cycles, were designed to investigate the exsolution responses for these complex pressure variation profiles. We found that the exsolved CO2 phase preferentially occupies the larger pores and exhibits a uniform spatial distribution. The mobility of CO2 is low during the imbibition process, and the residual trapping ratio is extraordinarily high. During the cyclic pressure variation process, the first cycle has the largest contribution to the amount of exsolved CO2. The low CO2 mobility implies a certain degree of self-sealing during a possible reservoir depletion. PMID:26509211

  9. Effects of genetic variation in H3K79 methylation regulatory genes on clinical blood pressure and blood pressure response to hydrochlorothiazide

    PubMed Central

    2012-01-01

    Background Nearly one-third of the United States adult population suffers from hypertension. Hydrochlorothiazide (HCTZ), one of the most commonly used medications to treat hypertension, has variable efficacy. The renal epithelial sodium channel (ENaC) provides a mechanism for fine-tuning sodium excretion, and is a major regulator of blood pressure homeostasis. DOT1L, MLLT3, SIRT1, and SGK1 encode genes in a pathway that controls methylation of the histone H3 globular domain at lysine 79 (H3K79), thereby modulating expression of the ENaCα subunit. This study aimed to determine the role of variation in these regulatory genes on blood pressure response to HCTZ, and secondarily, untreated blood pressure. Methods We investigated associations between genetic variations in this candidate pathway and HCTZ blood pressure response in two separate hypertensive cohorts (clinicaltrials.gov NCT00246519 and NCT00005520). In a secondary, exploratory analysis, we measured associations between these same genetic variations and untreated blood pressure. Associations were measured by linear regression, with only associations with P ≤ 0.01 in one cohort and replication by P ≤ 0.05 in the other cohort considered significant. Results In one cohort, a polymorphism in DOT1L (rs2269879) was strongly associated with greater systolic (P = 0.0002) and diastolic (P = 0.0016) blood pressure response to hydrochlorothiazide in Caucasians. However, this association was not replicated in the other cohort. When untreated blood pressure levels were analyzed, we found directionally similar associations between a polymorphism in MLLT3 (rs12350051) and greater untreated systolic (P < 0.01 in both cohorts) and diastolic (P < 0.05 in both cohorts) blood pressure levels in both cohorts. However, when further replication was attempted in a third hypertensive cohort and in smaller, normotensive samples, significant associations were not observed. Conclusions Our data suggest polymorphisms in DOT1L, MLLT3

  10. Spectral evaluation of aging effects on blood pressure and heart rate variations in healthy subjects.

    PubMed

    Singh, D; Vinod, K; Saxena, S C; Deepak, K K

    2006-01-01

    The background to heart rate variability (HRV) and blood pressure variability (BPV), and their determinants and physiological correlates, remain obscure. The impact of age must be taken into account if HRV and BPV are used for predictive purposes in clinical settings. Healthy subjects show wide inter-individual variation in their heart rate behaviour and the factors affecting heart rate dynamics are not well known. This paper has undertaken to evaluate heart rate variability (HRV) and baroreflex sensitivity (BRS) in a random sample of subjects without evidence of heart disease, and to estimate the relation of HRV and BPV behaviour to age. The aim of this study was to analyse the effects of ageing on HRV and BPV for simultaneous recordings of electrocardiograph (ECG) and blood pressure (BP) signals at rest in healthy subjects. We studied eight young (21-34 years old) and eight elderly (68-85 years old) rigorously screened subjects from the Fantasia Database to make the reproducibility and comparability of the results more extensive. Time- and frequency-domain analysis of HRV and BPV was performed on 5-minute ectopic-free recordings. BRS on the heart was estimated by frequency-domain analysis of spontaneous variability of systolic blood pressure (SBP) and RR interval. It has been observed that compared to young the elderly subjects have (i) diminished HRV; (ii) a shift in the power spectral density and median frequency to low frequency side for HRV and to higher frequency side for BPV; and (iii) increased low-frequency alpha index and decreased high-frequency alpha index of BRS with overall alpha index augmented. The results convey that normal ageing in the absence of disease is associated with lesser parasympathetic regulation of heart rate. Thus it is concluded that the age is an important factor to be considered for prognosis and diagnosis by HRV and BPV. For reliable clinical applications, more research needs to be done on a broad spectrum of subjects. In

  11. Pressure variation assisted fiber extraction and development of high performance natural fiber composites and nanocomposites

    NASA Astrophysics Data System (ADS)

    Markevicius, Gediminas

    It is believed, that due to the large surface areas provided by the nano scale materials, various composite properties could be enhanced when such particles are incorporated into a polymer matrix. There is also a trend of utilizing natural resources or reusing and recycling materials that are already available for the fabrication of the new composite materials. Cellulose is the most abundant natural polymer on the planet, and therefore it is not surprising to be of interest for composite fabrication. Basic structures of cellulose, comprised of long polysaccharide chains, are the building blocks of cellulose nano fibers. Nano fibers are further bound into micro fibrils and macro fibers. Theoretically pure cellulose nano fibers have tremendous strengths, and therefore are some of the most sought after nano particles. The fiber extraction however is a complex task. The ultrasound, which creates pressure variation in the medium, was employed to extract nano-size cellulose particles from microcrystalline cellulose (MCC). The length and the intensity of the cavitations were evaluated. Electron microscopy studies revealed that cellulose nanoparticles were successfully obtained from the MCC after ultrasound treatment of just 30 minutes. Structure of the fractionated cellulose was also analyzed with the help of X-ray diffraction, and its thermal properties were evaluated with the help of differential scanning calorimetry (DSC). Ultrasound treatment performed on the wheat straw, kenaf, and miscanthus particles altered fiber structure as a result of the cavitation. The micro fibers were generated from these materials after they were subjected to NaOH treatment followed by the ultrasound processing. The potential of larger than nano-sized natural fibers to be used for composite fabrication was also explored. The agricultural byproducts, such as wheat or rice straw, as well as other fast growing crops as miscanthus or kenaf, are comprised of three basic polymers. Just like in

  12. Seasonal Variations of the Earth's Gravitational Field: An Analysis of Atmospheric Pressure, Ocean Tidal, and Surface Water Excitation

    NASA Technical Reports Server (NTRS)

    Dong, D,; Gross, R.S.; Dickey, J.

    1996-01-01

    Monthly mean gravitational field parameters (denoted here as C(sub even)) that represent linear combinations of the primarily even degree zonal spherical harmonic coefficients of the Earth's gravitational field have been recovered using LAGEOS I data and are compared with those derived from gridded global surface pressure data of the National meteorological center (NMC) spanning 1983-1992. The effect of equilibrium ocean tides and surface water variations are also considered. Atmospheric pressure and surface water fluctuations are shown to be the dominant cause of observed annual C(sub even) variations. Closure with observations is seen at the 1sigma level when atmospheric pressure, ocean tide and surface water effects are include. Equilibrium ocean tides are shown to be the main source of excitation at the semiannual period with closure at the 1sigma level seen when both atmospheric pressure and ocean tide effects are included. The inverted barometer (IB) case is shown to give the best agreement with the observation series. The potential of the observed C(sub even) variations for monitoring mass variations in the polar regions of the Earth and the effect of the land-ocean mask in the IB calculation are discussed.

  13. The face of appearance-related social pressure: gender, age and body mass variations in peer and parental pressure during adolescence

    PubMed Central

    2013-01-01

    Background Appearance-related social pressure plays an important role in the development of a negative body image and self-esteem as well as severe mental disorders during adolescence (e.g. eating disorders, depression). Identifying who is particularly affected by social pressure can improve targeted prevention and intervention, but findings have either been lacking or controversial. Thus the aim of this study is to provide a detailed picture of gender, weight, and age-related variations in the perception of appearance-related social pressure by peers and parents. Methods 1112 German students between grades 7 and 9 (mean age: M = 13.38, SD = .81) filled in the Appearance-Related Social Pressure Questionnaire (German: FASD), which considers different sources (peers, parents) as well as various kinds of social pressure (e.g. teasing, modeling, encouragement). Results Girls were more affected by peer pressure, while gender differences in parental pressure seemed negligible. Main effects of grade-level suggested a particular increase in indirect peer pressure (e.g. appearance-related school and class norms) from early to middle adolescence. Boys and girls with higher BMI were particularly affected by peer teasing and exclusion as well as by parental encouragement to control weight and shape. Conclusion The results suggest that preventive efforts targeting body concerns and disordered eating should bring up the topic of appearance pressure in a school-based context and should strengthen those adolescents who are particularly at risk - in our study, girls and adolescents with higher weight status. Early adolescence and school transition appear to be crucial periods for these efforts. Moreover, the comprehensive assessment of appearance-related social pressure appears to be a fruitful way to further explore social risk-factors in the development of a negative body image. PMID:23680225

  14. Grain-scale pressure variations recorded in orthopyroxene from the diamond grade ultra-high pressure Svartberget peridotite body, Western Gneiss Region, Norway

    NASA Astrophysics Data System (ADS)

    Vrijmoed, Johannes C.

    2014-05-01

    The ultra-high pressure (UHP) area in the Western Gneiss Region (WGR) in Norway is recognized as a giant UHP domain that resulted from the collision of Baltica and Laurentia during the Caledonian Orogeny. Recent geochronological data suggest the WGR resided at UHP for several tens of millions of years and slowly exhumed near- isothermally to amphibolite facies conditions. The Svartberget peridotite body is located in the north-westernmost part of the UHP area of the WGR. The rocks record diamond grade peak metamorphism at ~800 ° C in crosscutting pyroxenite veins as evidenced by micro-diamond inclusions in Caledonian metamorphic garnet. The peridotite body preserves primary spinel-garnet-peridotite assemblages stable at much lower pressure (~2.0 GPa at ~800 ° C). Orthopyroxene typically shows bowl-shaped aluminium (Al) zoning and conventional geothermobarometry using core compositions of garnet-opx mineral pairs yields P-T estimates of 5.5 GPa at ~800 ° C. Besides Al increasing toward the rims of orthopyroxene grains, concentrations also increase in cracks and veins crosscutting the mineral. Here, recently developed unconventional geobarometry and Gibbs minimization methods are used to derive the grain-scale pressure variations corresponding to the observed Al-zoning. The methods independently result in pressure variations from core to rim on the order of 2.0 GPa. Interestingly, low-Al cores correspond to low pressures whereas high-Al rims correspond to high pressures, opposite to conventional geothermobarometry results. However, the new estimates are in agreement with the consideration that at high pressure the high density phases become more stable. In a binary orthopyroxene in the MAS-system, the Mg-Tschermak endmember thought to be the dominant Al-species in the mineral has a higher density then the Al-free enstatite endmember. Therefore at higher pressure the Mg-Tschermak endmember in orthopyroxene is favoured over the enstatite endmember. This is similar

  15. Measurement of systolic pressure variation during graded volume loss using simple tools on Datex Ohmeda S/5 monitor.

    PubMed

    Durga, Padmaja; Jonnavittula, Nirmala; Muthuchellappan, Radhakrishnan; Ramachandran, Gopinath

    2009-04-01

    Direct invasive arterial monitoring is performed routinely for all major neurosurgical procedures. Systolic pressure variation (SPV) used, independently or in combination with central venous pressure (CVP) allows optimal fluid management in hypovolemia and hemorrhage. This study aims to quantify SPV during graded hypovolemia using the simple technique described by Gouvea and Gouvea using Datex Ohmeda S/5, and to compare its reliability relative to other hemodynamic indicators of hypovolemia. Twenty anesthetized neurosurgical patients of ASA grade I and II patients were administered furosemide 0.5 mg/kg intravenously to obtain graded volume loss in the form of urine output. Invasive arterial pressure from radial artery and CVP were monitored using Datex OhmedaS/5 (Finland). Invasive arterial pressure label was changed to pulmonary artery label with the scale appropriate for arterial pressure. The trace was frozen in the wedge mode to reduce the sweep speed and the cursor was used to measure SPV and pulse pressure variation (PPV). Heart rate, systolic blood pressure, diastolic blood pressure, CVP at zero end-expiratory pressure, SPV and PPV are measured at baseline, and after a urine output of 200 and 500 mL. There was a significant correlation between volume loss and CVP, SPV, and PPV. The area under the curve of receiver operating characteristic analysis was >0.75 for CVP, SPV, and PPV. SPV of 7.5 mm Hg and a change of SPV by 4.5 mm Hg, a PPV of 4.5 and change in PPV by 2.5 mm Hg were the best cut-off values that corresponded to a volume change of 500 mL. This simple method enabled calculation of SPV without the computerized modules, and detected volume loss comparable to CVP. PMID:19295396

  16. THE RELATIONSHIP BETWEEN CIRCADIAN BLOOD PRESSURE VARIATION AND AGE ANALYSED FROM 7-DAY MONITORING

    PubMed Central

    SIEGELOVÁ, J.; DUŠEK, J.; FIŠER, B.; HOMOLKA, P.; VANK, P.; MAŠEK, M.; HAVELKOVÁ, A.; CORNÉLISSEN, G.; HALBERG, F.

    2009-01-01

    The relationship between age and circadian blood pressure (BP) variation was the aim of the present study. One hundred and eighty-seven subjects (130 males, 57 females), 20-77 years old, were recruited for seven-day BP monitoring. Colin medical instruments (Komaki, Japan) were used for ambulatory BP monitoring (oscillation method, 30-minute interval between measurements). A sinusoidal curve was fitted (minimum square method) and the mean value and amplitude of the curve (double amplitude corresponds to the night-day difference) were evaluated on every day of monitoring. The average 7-day values of the mean (M) and of double amplitude (2A) for systolic BP (SBP), diastolic BP (DBP), and heart rate (HR) were determined in each subject. The mean values of M (±SD) for the whole group were: SBP- 127±8, DBP - 79±6 mmHg, HR - 70±6 bpm; of 2A: SBP - 21±7, DBP - 15±5 mmHg, HR - 15±6 bpm. A linear relationship between M of SBP and age (r=0.341, p< 0.001) and DBP and age (r=0.384, p<0.001) was found (difference between 20 and 77 years: SBP - 16, DBP - 12 mmHg). 2A of SBP and DBP was increasing with age up to 35 years, then the curve remained relatively flat up to 55 years (maximum at 45 years), and then it decreased again (difference between 45 and 77 years: SBP - 13mmHg, DBP - 12 mmHg). Heart rate M and 2A were age-independent. The mean values of SBP and DBP were increasing with age up to 75 years, but the night-day difference of SBP and DBP reached its maximum value at 45 years and then decreased. PMID:19436777

  17. Widespread Sequence Variations in VAMP1 across Vertebrates Suggest a Potential Selective Pressure from Botulinum Neurotoxins

    PubMed Central

    Peng, Lisheng; Adler, Michael; Demogines, Ann; Borrell, Andrew; Liu, Huisheng; Tao, Liang; Tepp, William H.; Zhang, Su-Chun; Johnson, Eric A.; Sawyer, Sara L.; Dong, Min

    2014-01-01

    Botulinum neurotoxins (BoNT/A-G), the most potent toxins known, act by cleaving three SNARE proteins required for synaptic vesicle exocytosis. Previous studies on BoNTs have generally utilized the major SNARE homologues expressed in brain (VAMP2, syntaxin 1, and SNAP-25). However, BoNTs target peripheral motor neurons and cause death by paralyzing respiratory muscles such as the diaphragm. Here we report that VAMP1, but not VAMP2, is the SNARE homologue predominantly expressed in adult rodent diaphragm motor nerve terminals and in differentiated human motor neurons. In contrast to the highly conserved VAMP2, BoNT-resistant variations in VAMP1 are widespread across vertebrates. In particular, we identified a polymorphism at position 48 of VAMP1 in rats, which renders VAMP1 either resistant (I48) or sensitive (M48) to BoNT/D. Taking advantage of this finding, we showed that rat diaphragms with I48 in VAMP1 are insensitive to BoNT/D compared to rat diaphragms with M48 in VAMP1. This unique intra-species comparison establishes VAMP1 as a physiological toxin target in diaphragm motor nerve terminals, and demonstrates that the resistance of VAMP1 to BoNTs can underlie the insensitivity of a species to members of BoNTs. Consistently, human VAMP1 contains I48, which may explain why humans are insensitive to BoNT/D. Finally, we report that residue 48 of VAMP1 varies frequently between M and I across seventeen closely related primate species, suggesting a potential selective pressure from members of BoNTs for resistance in vertebrates. PMID:25010769

  18. Widespread sequence variations in VAMP1 across vertebrates suggest a potential selective pressure from botulinum neurotoxins.

    PubMed

    Peng, Lisheng; Adler, Michael; Demogines, Ann; Borrell, Andrew; Liu, Huisheng; Tao, Liang; Tepp, William H; Zhang, Su-Chun; Johnson, Eric A; Sawyer, Sara L; Dong, Min

    2014-07-01

    Botulinum neurotoxins (BoNT/A-G), the most potent toxins known, act by cleaving three SNARE proteins required for synaptic vesicle exocytosis. Previous studies on BoNTs have generally utilized the major SNARE homologues expressed in brain (VAMP2, syntaxin 1, and SNAP-25). However, BoNTs target peripheral motor neurons and cause death by paralyzing respiratory muscles such as the diaphragm. Here we report that VAMP1, but not VAMP2, is the SNARE homologue predominantly expressed in adult rodent diaphragm motor nerve terminals and in differentiated human motor neurons. In contrast to the highly conserved VAMP2, BoNT-resistant variations in VAMP1 are widespread across vertebrates. In particular, we identified a polymorphism at position 48 of VAMP1 in rats, which renders VAMP1 either resistant (I48) or sensitive (M48) to BoNT/D. Taking advantage of this finding, we showed that rat diaphragms with I48 in VAMP1 are insensitive to BoNT/D compared to rat diaphragms with M48 in VAMP1. This unique intra-species comparison establishes VAMP1 as a physiological toxin target in diaphragm motor nerve terminals, and demonstrates that the resistance of VAMP1 to BoNTs can underlie the insensitivity of a species to members of BoNTs. Consistently, human VAMP1 contains I48, which may explain why humans are insensitive to BoNT/D. Finally, we report that residue 48 of VAMP1 varies frequently between M and I across seventeen closely related primate species, suggesting a potential selective pressure from members of BoNTs for resistance in vertebrates. PMID:25010769

  19. The Co-evolution of Speech and the Lexicon: The Interaction of Functional Pressures, Redundancy, and Category Variation.

    PubMed

    Winter, Bodo; Wedel, Andrew

    2016-04-01

    The sound system of a language must be able to support a perceptual contrast between different words in order to signal communicatively relevant meaning distinctions. In this paper, we use a simple agent-based exemplar model in which the evolution of sound-category systems is understood as a co-evolutionary process, where the range of variation within sound categories is constrained by functional pressure to keep different words perceptually distinct. We show that this model can reproduce several observed effects on the range of sound variation. We argue that phonological systems can be seen as finding a relative optimum of variation: Efficient communication is sustained while at the same time, hidden category variation provides pathways for future evolution. PMID:26988575

  20. Magnetic Flux Transport and Pressure Variations at Magnetotail Plasma Flow Bursts during Geomagnetically Quiet Times

    NASA Astrophysics Data System (ADS)

    Nowada, M.; Fu, S.-Y.; Parks, G. K.; Pu, Z.-Y.; Angelopoulos, V.; Carlson, C. W.; Auster, H.-U.

    2012-04-01

    The fast plasma flows in the geomagnetotail are observed during both geomagnetically active and quiet times. However, it has been unclear about the fundamental difference in the plasma fast flows between at two different geomagnetic conditions, that is, the generation mechanism of, and pictures of the energy transport and balance at the fast plasma flows. Magnetic reconnection in the magnetotail has been believed as one of the most possible mechanisms to generate the fast plasma flows regardless of the geomagnetic conditions. Recently, Nowada et al. [2012], however, demonstrated that the magnetotail magnetic reconnection does not always contribute to the generation of the fast plasma flows at geomagnetically quiet times based on the THEMIS measurements. It is very important to reveal how the energy transport and balance in the magnetotail in association with these plasma fast flows are on obtaining a clue to elucidate an essential difference in the plasma fast flows between during active and quiet geomagnetic conditions. Based on three events of the magnetotail plasma flow bursts, which are transient fast plasma flows with the durations between 1 and 2 minutes, during geomagnetically quiet times, observed by THEMIS, we examined detailed variations of the electric field as a proxy of the flux transport aspect, and associated pressure. The main characteristics of these events are shown as follows; 1) the GSM-X component of the plasma velocity (Vx) was higher than 300 km/s 2) associated parallel (V//) and perpendicular (V⊥) velocities to the local magnetic field line were higher than 200 km/s 3) the flow bursts were observed during which AL and AU indices were lower than 40 nT, and simultaneous Kp index range was between -1 and 1. For almost events, the parallel (E//) and perpendicular (E⊥) components of the electric field to the local magnetic field line were much stronger than the dawn-dusk electric field component (Ey). This result implies that a larger amount

  1. Pressure variation by a magnetohydrodynamic method at the surface of a body placed in a supersonic flow

    NASA Astrophysics Data System (ADS)

    Lapushkina, T. A.; Erofeev, A. V.; Ponyaev, S. A.

    2014-07-01

    This study is aimed at investigating the possibility of pressure variation near the surface of a body placed in a supersonic flow as a model of an aerofoil or the nose of an aircraft by organizing a surface gas discharge in a magnetic field transverse to the flow. The flow parameters and pressure are mainly affected by the ponderomotive Lorentz force acting on the gas in the direction orthogonal to the direction of the organized discharge current and leading to the removal or compression of the gas at the surface of the body and, hence, a variation of pressure. Experimental data on the visualization of the flow and on the pressure at the surface of the body are considered for various configurations of the current and intensities of the gas discharge and magnetic field; it is demonstrated that such configurations of the current and magnetic field near the surface of the body under investigation can be organized in such a way that the pressure at the front part as well as the upper and lower surfaces of the body under investigation can be increased or decreased, thus changing the aerodynamic drag and the aerofoil lift. Such a magnetohydrodynamic control over aerodynamic parameters of the aircraft can be used during takeoff and landing as well as during steady-state flight and also during the entrance into dense atmospheric layers. This will considerably reduce the thermal load on the surface of the body in the flow.

  2. Experimental and analytical investigation on the variation of spray characteristics along radial distance downstream of a pressure swirl atomizer

    NASA Astrophysics Data System (ADS)

    Zhao, Y. H.; Li, W. M.; Chin, J. S.

    1986-06-01

    The variation of spray characteristics (Sauter Mean Diameter and Rosin-Rammler drop-size distribution parameter) downstream of a pressure swirl atomizer along radial distance has been measured by laser light scattering technology. An analytical model has been developed that is capable of predicting the variation of spray characteristics along radial distance. A comparison between the prediction and experimental data shows excellent agreement. It shows that the spray model proposed, although relatively simple, is correct and can be used with some expansion and modification to predict more complicated spray systems.

  3. Investigation of temperature and barometric pressure variation effects on radon concentration in the Sopronbánfalva Geodynamic Observatory, Hungary.

    PubMed

    Mentes, Gyula; Eper-Pápai, Ildikó

    2015-11-01

    Radon concentration variation has been monitored since 2009 in the artificial gallery of the Sopronbánfalva Geodynamic Observatory, Hungary. In the observatory, the radon concentration is extremely high, 100-600 kBq m(-3) in summer and some kBq m(-3) in winter. The relationships between radon concentration, temperature and barometric pressure were separately investigated in the summer and winter months by Fast Fourier Transform, Principal Component Analysis, Multivariable Regression and Partial Least Square analyses in different frequency bands. It was revealed that the long-period radon concentration variation is mainly governed by the temperature (20 kBq m(-1) °C(-1)) both in summer and winter. The regression coefficients between long-period radon concentration and barometric pressure are -1.5 kBq m(-3) hPa(-1) in the summer and 5 kBq m(-3) hPa(-1) in the winter months. In the 0.072-0.48 cpd (cycles per day) frequency band the effect of the temperature is about -1 kBq m(-3) °C(-1) and that of the barometric pressure is -5 kBq m(-3) hPa(-1) in summer and -0.5 kBq m(-3) hPa(-1) in winter. In the high frequency range (>0.48 cpd) all regression coefficients are one order of magnitude smaller than in the range of 0.072-0.48 cpd. Fast Fourier Transform of the radon concentration, temperature and barometric pressure time series revealed S1, K1, P1, S2, K2, M2 tidal constituents in the data and weak O1 components in the radon concentration and barometric pressure series. A detailed tidal analysis, however, showed that the radon tidal components are not directly driven by the gravitational force but rather by solar radiation and barometric tide. Principal Component Analysis of the raw data was performed to investigate the yearly, summer and winter variability of the radon concentration, temperature and barometric pressure. In the summer and winter periods the variability does not change. The higher variability of the radon concentration compared to the variability of

  4. Variation in Lithium Isotopes During Fluid-Shale Interactions at Elevated Pressure and Temperature

    NASA Astrophysics Data System (ADS)

    Phan, T. T.; Paukert, A. N.; Hakala, A.

    2015-12-01

    Naturally-occurring isotopes are useful tracers of fluid mixing in complex natural systems, and have been applied towards evaluating the sources of elevated total dissolved solids in water produced from unconventional oil and gas operations. Prior investigations showed that elevated Li in saline waters co-produced with natural gas during Marcellus Shale development resulted from mixing of hydraulic fracturing fluid (HFF) and Li-rich formation water. However, specific contributions to the Li isotope signature from reactions between the HFF and shale remained unclear. This study focused on HFF-shale reactions that could affect the Li budget and isotope composition in Marcellus Shale produced water in a series of flow through experiments conducted at fixed temperature and pressure (66oC, 20MPa) comparable to formation conditions. Synthetic HFF was prepared by mixing either freshwater or a lab-derived saline water with chemical additives commonly used in hydraulic fracturing. Outcrop cores of Marcellus Shale were artificially fractured either parallel to or perpendicular to bedding prior to loading into the flow-through apparatus, and each experiment was performed with a unique HFF composition continuously pumped through a fresh core (15 cm in length, 3.8 cm in diameter). Initial fluid and cumulative effluents collected after 2 days and 7 days from the start of the experiment were measured for concentrations of cations and anions. Multi-collector ICP-MS was used to measure lithium isotope ratios (δ7Li). Preliminary results show that dissolution of carbonate minerals occurred in both replicate experiments with freshwater-based HFF (pH 2) as shown by a large decrease in Li/Ca from 0.8 (initial fluid) to 0.003 (effluents on day 2 and day 7) with no significant change in Li concentration. This is consistent with low Li in carbonate cement (<2%) and water soluble (<8%) and exchangeable (<2%) fractions of Marcellus Shale. Variation in δ7Li values is within analytical

  5. Sunspot random walk and 22-year variation

    USGS Publications Warehouse

    Love, Jeffrey J.; Rigler, E. Joshua

    2012-01-01

    We examine two stochastic models for consistency with observed long-term secular trends in sunspot number and a faint, but semi-persistent, 22-yr signal: (1) a null hypothesis, a simple one-parameter random-walk model of sunspot-number cycle-to-cycle change, and, (2) an alternative hypothesis, a two-parameter random-walk model with an imposed 22-yr alternating amplitude. The observed secular trend in sunspots, seen from solar cycle 5 to 23, would not be an unlikely result of the accumulation of multiple random-walk steps. Statistical tests show that a 22-yr signal can be resolved in historical sunspot data; that is, the probability is low that it would be realized from random data. On the other hand, the 22-yr signal has a small amplitude compared to random variation, and so it has a relatively small effect on sunspot predictions. Many published predictions for cycle 24 sunspots fall within the dispersion of previous cycle-to-cycle sunspot differences. The probability is low that the Sun will, with the accumulation of random steps over the next few cycles, walk down to a Dalton-like minimum. Our models support published interpretations of sunspot secular variation and 22-yr variation resulting from cycle-to-cycle accumulation of dynamo-generated magnetic energy.

  6. Sunspot random walk and 22-year variation

    NASA Astrophysics Data System (ADS)

    Love, Jeffrey J.; Rigler, E. Joshua

    2012-05-01

    We examine two stochastic models for consistency with observed long-term secular trends in sunspot number and a faint, but semi-persistent, 22-yr signal: (1) a null hypothesis, a simple one-parameter log-normal random-walk model of sunspot-number cycle-to-cycle change, and, (2) an alternative hypothesis, a two-parameter random-walk model with an imposed 22-yr alternating amplitude. The observed secular trend in sunspots, seen from solar cycle 5 to 23, would not be an unlikely result of the accumulation of multiple random-walk steps. Statistical tests show that a 22-yr signal can be resolved in historical sunspot data; that is, the probability is low that it would be realized from random data. On the other hand, the 22-yr signal has a small amplitude compared to random variation, and so it has a relatively small effect on sunspot predictions. Many published predictions for cycle 24 sunspots fall within the dispersion of previous cycle-to-cycle sunspot differences. The probability is low that the Sun will, with the accumulation of random steps over the next few cycles, walk down to a Dalton-like minimum. Our models support published interpretations of sunspot secular variation and 22-yr variation resulting from cycle-to-cycle accumulation of dynamo-generated magnetic energy.

  7. The influence of thermal inertia on Mars' seasonal pressure variation and the effect of the weather component

    NASA Technical Reports Server (NTRS)

    Wood, S. E.; Paige, D. A.

    1993-01-01

    Using a Leighton-Murray type diurnal and seasonal Mars thermal model, we found that it is possible to reproduce the seasonal variation in daily-averaged pressures (approximately 680-890 Pa) measured by Viking Lander 1 (VL1), during years without global dust storms, with a standard deviation of less than 5 Pa. In this simple model, surface CO2, frost condensation, and sublimation rates at each latitude are determined by the net effects of radiation, latent heat, and heat conduction in subsurface soil layers. An inherent assumption of our model is that the seasonal pressure variation is due entirely to the exchange of mass between the atmosphere and polar caps. However, the results of recent Mars GCM modeling have made it clear that there is a significant dynamical contribution to the seasonal pressure variation. This 'weather' component is primarily due to large-scale changes in atmospheric circulation, and its magnitude depends somewhat on the dust content of the atmosphere. The overall form of the theoretical weather component at the location of VL1, as calculated by the AMES GCM, remains the same over the typical range of Mars dust opacities.

  8. Association between stress and blood pressure variation in a Caribbean population.

    PubMed

    Hutchinson, J

    1986-09-01

    Based on the work of Selye (The Stress of Life, New York: McGraw-Hill, 1976) it is hypothesized that stress can produce physiological abnormalities, i.e., elevated blood pressure, and that social variables can be used as indicators or risk factors for disease. It is theorized that deviations from acceptable social patterns or traditional life-styles can produce stressful conditions that are associated with disease and that these situations can be demonstrated by examination of certain social characteristics. This association is examined among the Black Caribs of St. Vincent, West Indies. The social variables included in this analysis are marital status (single, married, widowed, or separated), frequency of church attendance (frequently, sometimes, seldom, or never), years of education, and number of children (for women only). The findings show that single individuals have higher pressures than married subjects and that males who never attend church have higher pressures than men who frequently attend church; a relationship was not demonstrated for females. Among males, as the years of education increased, blood pressure also increased, but for females, increased education was associated with lower pressures. Family size was not associated with systolic or diastolic pressure. The analysis of these selected social variables suggests that these variables influence male systolic and diastolic pressures, but only female diastolic pressure. PMID:3777149

  9. Pressure driven currents near magnetic islands in 3D MHD equilibria: Effects of pressure variation within flux surfaces and of symmetry

    NASA Astrophysics Data System (ADS)

    Reiman, Allan H.

    2016-07-01

    In toroidal, magnetically confined plasmas, the heat and particle transport is strongly anisotropic, with transport along the field lines sufficiently strong relative to cross-field transport that the equilibrium pressure can generally be regarded as constant on the flux surfaces in much of the plasma. The regions near small magnetic islands, and those near the X-lines of larger islands, are exceptions, having a significant variation of the pressure within the flux surfaces. It is shown here that the variation of the equilibrium pressure within the flux surfaces in those regions has significant consequences for the pressure driven currents. It is further shown that the consequences are strongly affected by the symmetry of the magnetic field if the field is invariant under combined reflection in the poloidal and toroidal angles. (This symmetry property is called "stellarator symmetry.") In non-stellarator-symmetric equilibria, the pressure-driven currents have logarithmic singularities at the X-lines. In stellarator-symmetric MHD equilibria, the singular components of the pressure-driven currents vanish. These equilibria are to be contrasted with equilibria having B ṡ∇p =0 , where the singular components of the pressure-driven currents vanish regardless of the symmetry. They are also to be contrasted with 3D MHD equilibrium solutions that are constrained to have simply nested flux surfaces, where the pressure-driven current goes like 1 /x near rational surfaces, where x is the distance from the rational surface, except in the case of quasi-symmetric flux surfaces. For the purpose of calculating the pressure-driven currents near magnetic islands, we work with a closed subset of the MHD equilibrium equations that involves only perpendicular force balance, and is decoupled from parallel force balance. It is not correct to use the parallel component of the conventional MHD force balance equation, B ṡ∇p =0 , near magnetic islands. Small but nonzero values of B

  10. Therapeutic Consequences of Variation in Intraarterial Pressure Measurements After Iliac Angioplasty

    SciTech Connect

    Tetteroo, Eric; Haaring, Cees; Engelen, Andries D. van; Graaf, Yolanda van der; Mali, Willem P.T.M.

    1997-11-15

    Purpose: To assess the accuracy of intraarterial measurement of transstenotic pressure gradients for the detection of hemodynamically suboptimal iliac angioplasty. Methods: In 14 patients, referred for diagnostic angiography, mean pressure gradients in the aorta and iliac artery were obtained twice, using a double-sensor pressure catheter. Additional iliac measurements were performed during pharmacologically induced flow augmentation. Repeatability was assessed by calculation of the mean difference plus standard deviation (MD {+-} SD) and repeatability coefficient (2 x SD). These results were extrapolated to 137 iliac angioplasty procedures with secondary stenting where there was a residual pressure gradient > 10 mmHg. Results: MD {+-} SD for repeated measurements at rest and during flow augmentation were 0 {+-} 2 mmHg and 1 {+-} 3 mmHg, respectively. Repeatability coefficients were 3 and 6 mmHg. Mean pressure gradients after hemodynamically insufficient angioplasty were 8 {+-} 7 mmHg at rest and 17 {+-} 5 mmHg following vasodilatation. Inaccurate pressure recordings may have led to inappropriate stent placement in less than 2.5%, and inappropriate denial of stent placement in less than 5% of the lesions. Conclusion: Variability of intraarterial pressure measurements has little consequence in the detection of hemodynamically significant stenosis after angioplasty.

  11. Effect of ambient pressure variation on closed loop gas system for India based Neutrino Observatory (INO)

    NASA Astrophysics Data System (ADS)

    Satyanarayana, B.; Majumder, G.; Mondal, N. K.; Kalmani, S. D.; Shinde, R. R.; Joshi, A.

    2014-10-01

    Pilot unit of a closed loop gas mixing and distribution system for the INO project was designed and is being operated with 1.8meters × 1.9meters RPCs for about two years. A number of studies on controlling the flow and optimisation of the gas mixture through the RPC stack were carried out during this period. The gas system essentially measures and attempts to maintain absolute pressure inside the RPC gas volume. During typical Mumbai monsoon seasons, the barometric pressure changes rather rapidly, due to which the gas system fails to maintain the set differential pressure between the ambience and the RPC gas volume. As the safety bubblers on the RPC gas input lines are set to work on fixed pressure differentials, the ambient pressure changes lead to either venting out and thus wasting gas through safety bubblers or over pressuring the RPCs gas volume and thus degrading its performance. The above problem also leads to gas mixture contamination through minute leaks in gas gap. The problem stated above was solved by including the ambient barometric pressure as an input parameter in the closed loop. Using this, it is now possible to maintain any set differential pressure between the ambience and RPC gas volumes between 0 to 20mm of water column, thus always ensuring a positive pressure inside the RPC gas volume with respect to the ambience. This has resulted in improved performance of the gas system by maintaining the constant gas flow and reducing the gas toping up frequency. In this paper, we will highlight the design features and improvements of the closed loop gas system. We will present some of the performance studies and considerations for scaling up the system to be used with the engineering module and then followed by Iron Calorimeter detector (ICAL), which is designed to deploy about 30,000 RPCs of 1.8meters × 1.9 meters in area.

  12. Alterations of Blood Flow Through Arteries Following Atherectomy and the Impact on Pressure Variation and Velocity.

    PubMed

    Plourde, Brian D; Vallez, Lauren J; Sun, Biyuan; Nelson-Cheeseman, Brittany B; Abraham, John P; Staniloae, Cezar S

    2016-09-01

    Simulations were made of the pressure and velocity fields throughout an artery before and after removal of plaque using orbital atherectomy plus adjunctive balloon angioplasty or stenting. The calculations were carried out with an unsteady computational fluid dynamic solver that allows the fluid to naturally transition to turbulence. The results of the atherectomy procedure leads to an increased flow through the stenotic zone with a coincident decrease in pressure drop across the stenosis. The measured effect of atherectomy and adjunctive treatment showed decrease the systolic pressure drop by a factor of 2.3. Waveforms obtained from a measurements were input into a numerical simulation of blood flow through geometry obtained from medical imaging. From the numerical simulations, a detailed investigation of the sources of pressure loss was obtained. It is found that the major sources of pressure drop are related to the acceleration of blood through heavily occluded cross sections and the imperfect flow recovery downstream. This finding suggests that targeting only the most occluded parts of a stenosis would benefit the hemodynamics. The calculated change in systolic pressure drop through the lesion was a factor of 2.4, in excellent agreement with the measured improvement. The systolic and cardiac-cycle-average pressure results were compared with measurements made in a multi-patient study treated with orbital atherectomy and adjunctive treatment. The agreements between the measured and calculated systolic pressure drop before and after the treatment were within 3%. This excellent agreement adds further confidence to the results. This research demonstrates the use of orbital atherectomy to facilitate balloon expansion to restore blood flow and how pressure measurements can be utilized to optimize revascularization of occluded peripheral vessels. PMID:27333887

  13. Sediment budget variation at watershed scale due to anthropogenic pressures, and its relationship to coastal erosion

    NASA Astrophysics Data System (ADS)

    Aiello, Antonello; Adamo, Maria; Canora, Filomena

    2014-05-01

    The transfer of sediments from hydrographic basins towards the coast is a significant pathway of material transfer on Earth. In sedimentary environment, the main portion of sediment that enters the coastal areas is derived originally from erosion in the coastal watersheds. Extensive anthropogenic pressures carried out within coastal basins have long shown negative impacts on littoral environments. In fluvial systems, sediments trapped behind dams and in-stream gravel mining cause the reduction in sediment supply to the coast. Along the Jonian littoral of the Basilicata Region (southern Italy), natural coastal processes have been severely disrupted since the second half of the 20th century as a result of riverbed sand and gravel mining and dam construction, when economic advantages were measured in terms of the development of infrastructure, water storage, and hydropower production for the agricultural, industrial and socio-economic development of the area. Particularly, the large numbers of dams and impoundments that have been built in the hydrographic basins have led a signi?cant reduction on river sediment loads. As a result, the Jonian littoral is experiencing a catalysed erosion phenomenon. In order to increase understanding of the morpho-dynamics of the Jonian littoral environment and more fully appreciate the amount of coastal erosion, an evaluation of the sediment budget change due to dam construction within the hydrographic basins of the Basilicata Region needs to be explored. Since quantitative data on decadal trends in river sediment supply before and after dam construction are lacking, as well as updated dam silting values, river basin assessment of the spatial patterns and estimated amount of sediment erosion and deposition are important in evaluating changes in the sediment budget. As coastal areas are being affected by an increasing number of population and socio-economic activities, the amount of sediment deficit at the littoral can permit to

  14. The variation in pressure in the cabin of an airplane in flight

    NASA Technical Reports Server (NTRS)

    Gough, Melvin N

    1931-01-01

    The pressure in the cabin of a Fairchild cabin monoplane wa surveyed in flight, and was found to decrease with increased air speed over the fuselage and to vary with the number and location of openings in the cabin. The maximum depression of 2.2 inches of water (equivalent pressure altitude at sea level of 152 feet) occurred at the high speed of the airplane in level flight with the cabin closed.

  15. Arterial Pressure Variation as a Biomarker of Preload Dependency in Spontaneously Breathing Subjects – A Proof of Principle

    PubMed Central

    Bronzwaer, Anne-Sophie G. T.; Ouweneel, Dagmar M.; Stok, Wim J.; Westerhof, Berend E.; van Lieshout, Johannes J.

    2015-01-01

    Objective Pulse (PPV) and systolic pressure variation (SPV) quantify variations in arterial pressure related to heart-lung interactions and have been introduced as biomarkers of preload dependency to guide fluid treatment in mechanically ventilated patients. However, respiratory intra-thoracic pressure changes during spontaneous breathing are considered too small to affect preload and stroke volume sufficiently for the detection by PPV and/or SPV. This study addressed the effects of paced breathing and/or an external respiratory resistance on PPV and SPV in detecting preload dependency in spontaneously breathing subjects. Methods In 10 healthy subjects, hemodynamic and respiratory parameters were evaluated during progressive central hypovolemia (head-up tilt). Breathing conditions were varied by manipulating breathing frequency and respiratory resistance. Subjects responding with a reduction in stroke volume index ≥15% were classified as having developed preload dependency. The ability for PPV and SPV to predict preload dependency was expressed by the area under the ROC curve (AUC). Results A breathing frequency at 6/min increased the PPV (16±5% vs. 10±3%, p<0.001) and SPV (9±3% vs. 5±2%, p<0.001) which was further enhanced by an expiratory resistance (PPV: 19±3%, p = 0.025 and SPV: 10±2%, p = 0.047). These respiratory modifications, compared to free breathing, enhanced the predictive value of PPV with higher accuracy (AUC: 0.92 vs. 0.46). Conclusion Under conditions of progressive central hypovolemia, the application of an external respiratory resistance at a breathing frequency of 6/min enhanced PPV and SPV and is worth further study for detection of preload dependency from arterial pressure variations in non-ventilated subjects. PMID:26335939

  16. Postural-induced phase shift of respiratory sinus arrhythmia and blood pressure variations: insight from respiratory-phase domain analysis.

    PubMed

    Kotani, Kiyoshi; Takamasu, Kiyoshi; Jimbo, Yasuhiko; Yamamoto, Yoshiharu

    2008-03-01

    The purpose of this study is to evaluate the multiple effects of respiration on cardiovascular variability in different postures, by analyzing respiratory sinus arrhythmia (RSA) and respiratory-related blood pressure (BP) variations for systolic BP (SBP), diastolic BP (DBP), and pulse pressure (PP) in the respiratory-phase domain. The measurements were conducted for 420 s on healthy humans in the sitting and standing positions, while the subjects were continuously monitored for heart rate and BP variability and instantaneous lung volume. The waveforms of RSA and respiratory-related BP variations were extracted as a function of the respiratory phase. In the standing position, the waveforms of the BP variations for SBP, DBP, and PP show their maxima at around the end of expiration (pi rad) and the minima at around the end of inspiration (2 pi rad), while the waveform of RSA is delayed by approximately 0.35 pi rad compared with the BP waveforms. On the other hand, in the sitting position, the phase of the DBP waveform (1.69 pi rad) greatly and significantly (P < 0.01) differs from that in the standing position (1.20 pi rad). Also, the phase of PP is delayed and that of RSA is advanced in the sitting position (P < 0.01). In particular, the phase shift of the DBP waveform is sufficiently large to alter whole hemodynamic fluctuations, affecting the amplitudes of SBP and PP variations. We conclude that the postural change associated with an altered autonomic balance affects not only the amplitude of RSA, but also the phases of RSA and BP variations in a complicated manner, and the respiratory-phase domain analysis used in this study is useful for elucidating the dynamic mechanisms of RSA. PMID:18223194

  17. Use of systolic pressure variation to predict the cardiovascular response to mini-fluid challenge in anaesthetised dogs.

    PubMed

    Rabozzi, R; Franci, P

    2014-11-01

    Systolic pressure variation (SPV), the maximum variation in systolic pressure values following a single positive pressure breath delivered by controlled mechanical ventilation (CMV), is highly correlated with volaemia in dogs. The aim of this study was to determine an SPV value that would indicate when fluid administration would be beneficial in clinical practice. Twenty-six client-owned dogs were anaesthetised, following which CMV with a peak inspiratory pressure (PIP) of 8 cmH2O was applied. After SPV measurement and recording of heart rate (HR) and blood pressure (BP), 3 mL/kg fluid were administered, then HR and BP were recorded again. Dogs exhibiting a 10% decrease in HR and/or an increase in BP were defined as responders, and their SPV pre-bolus was analysed retrospectively. SPV values > 4 mmHg or >4.5% predicted haemodynamic improvement in dogs with normal cardiovascular function, with a sensitivity of 90% and a specificity of 87%. The area under the curve receiver operating characteristic value for SPV was 0.931 mmHg (95% confidence interval, CI, 0.76-0.99 mmHg) and 0.944% (95% CI 0.78-0.99%). It is proposed that SPV values > 4.5% in dogs with a normal cardiovascular function, anaesthetised with isoflurane in oxygen and air, and on CMV (PIP 8 cmH2O), can be used to predict a cardiovascular response (>10% increase in mean arterial BP and/or >10% decrease in heart rate). PMID:25199508

  18. Pressure induced variation of second harmonic efficiency of K3B6O10Cl

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Kong, Lingyao; Zhao, Xiaoyan; Lv, Zhenlong; Li, Tongwei; Ju, Wei Wei; You, Jinghan; Bai, Ying

    2013-09-01

    K3B6O10Cl is a perovskite-like nonlinear optical (NLO) crystal, which exhibits large second harmonic generation (SHG) response. Based on density-functional theory, we investigate the influence of pressure on SHG tensor of K3B6O10Cl. At zero pressure, the non-centrosymmetric distortion of K3B6O10Cl from BO4 tetrahedron results in the similar SHG tensor to β-BaB2O4 (BBO). At 50 GPa, the ClK6 octahedron distortion of K3B6O10Cl becomes the main source of SHG and give similar SHG tensor to LiNbO3. Therefore, pressure induces K3B6O10Cl from a BBO-like NLO material to a LiNbO3-like NLO material.

  19. Variation with Mach Number of Static and Total Pressures Through Various Screens

    NASA Technical Reports Server (NTRS)

    Adler, Alfred A

    1946-01-01

    Tests were conducted in the Langley 24-inch highspeed tunnel to ascertain the static-pressure and total-pressure losses through screens ranging in mesh from 3 to 12 wires per inch and in wire diameter from 0.023 to 0.041 inch. Data were obtained from a Mach number of approximately 0.20 up to the maximum (choking) Mach number obtainable for each screen. The results of this investigation indicate that the pressure losses increase with increasing Mach number until the choking Mach number, which can be computed, is reached. Since choking imposes a restriction on the mass rate of flow and maximum losses are incurred at this condition, great care must be taken in selecting the screen mesh and wire dimmeter for an installation so that the choking Mach number is

  20. Effect of geometric variations on pressure loss for a model bifurcation of the human lung airway.

    PubMed

    Kang, Min-Yeong; Hwang, Jeongeun; Lee, Jin-Won

    2011-04-01

    Characteristics of pressure loss (ΔP) in human lung airways were numerically investigated using a realistic model bifurcation. Flow equations were numerically solved for the steady inspiratory condition with the tube length, the branching angle and flow velocity being varied over a wide range. In general, the ΔP coefficient K showed a power-law dependence on Reynolds number (Re) and length-to-diameter ratio with a different exponent for Re≥100 than for Re<100. The effect of different branching angles on pressure loss was very weak in the smooth-branching airways. PMID:21354574

  1. Within-Tunnel Variations in Pressure Data for Three Transonic Wind Tunnels

    NASA Technical Reports Server (NTRS)

    DeLoach, Richard

    2014-01-01

    This paper compares the results of pressure measurements made on the same test article with the same test matrix in three transonic wind tunnels. A comparison is presented of the unexplained variance associated with polar replicates acquired in each tunnel. The impact of a significance component of systematic (not random) unexplained variance is reviewed, and the results of analyses of variance are presented to assess the degree of significant systematic error in these representative wind tunnel tests. Total uncertainty estimates are reported for 140 samples of pressure data, quantifying the effects of within-polar random errors and between-polar systematic bias errors.

  2. The influence of bandage characteristics and inter-individual application variations on underneath bandage pressures.

    PubMed

    Morlock, MM; Nassutt, R; Bonin, V

    1997-04-01

    INTRODUCTION:: Cohesive bandages are applied to the legs of racehorses and horses with limb injuries for protection (prevention of abrasion) and support (reduction of movement at the fetlock joint). The support capacity of all commercially available bandages has been questioned. Consequently, the protection aspect of bandaging and the negative side effects, which can be caused by bandaging (eg pressure induced ischemia with subsequent necrosis), were emphasized. High pressures underneath bandages were shown to cause reduced blood flow. Pressures underneath certain types of bandages were shown to be higher than under others. It is unclear if these differences were due to differences in material characteristics between the bandage types or caused by differences in application by the trainers. The purpose of this study was to determine (a) if differences between different types of bandages are observed if these are applied similarly and (b) if earlier observed differences in pressures underneath bandages are reproducible when wrapped by different trainers. METHODS AND MATERIAL:: (a) A wrapping machine for the application of bandages to an artificial joint (simulating the human knee joint) was designed and built. The machine allows to wrap bandages with adjustable, constant tension under well defined wrapping angles in order to simulate a wrapping technique similar to the wrapping by trainers. The artificial joint is equipped with two pressure sensors (Parotec, Germany). After bandage application, the artificial joint was placed in a specially designed testing machine and cycled through 200 cycles from 0 degrees to 90 degrees of flexion at a frequency of 0.5 Hz. Pressure data were collected at a frequency of 20 Hz. The force required to unwind the bandage from its core was measured with a material testing machine. Five samples each of four different 4" wide cohesive bandages were tested: 'E': high modulus latex, 'V': low mod. latex, 'C': low mod. latex, 'F': medium mod

  3. Analysis of lower atmosphere pressure field response for short-time cosmic ray variations by Multifield Comparison Measure method

    NASA Astrophysics Data System (ADS)

    Artamonova, I. V.; Volobuev, D. M.; Makarenko, N. G.

    2016-02-01

    Pressure variation in lower atmosphere which take place after intensive solar proton events and Forbush-decreases of galactic cosmic rays (GCRs) are analyzed for the period 1980-2006. There were plotted groups of charts (multifields) for 48 solar proton events with energies of particles Ep > 90 MeV and for 48 Forbush-decreases of GCRs with amplitudes dN/N > 2.5%. These multifields revealed a growth of matrix norm over North Atlantic region and North of European part of Russia during days following the bursts of solar protons and Forbush-decreases of GCRs, respectively. These results confirm hypothesis about relation of regional cyclogenesis processes with short-term variations of solar and galactic cosmic rays.

  4. Variations in 7-day/24-h circadian pattern of ambulatory blood pressure and heart rate of type 2 diabetes patients

    PubMed Central

    Bhardwaj, Shipra; Verma, Narsingh; Anjum, Baby; Bhardwaj, Kshitij

    2014-01-01

    Aims/Introduction Diabetes has profound consequences on the cardiovascular system leading to cardiovascular morbidity and mortality in diabetic patients. Blood pressure (BP) has a characteristic and reproducible circadian pattern, with high values during the day and low values at night. A 7-day timed analysis of BP through ambulatory blood pressure monitoring has been used not only to diagnose day and night dipping patterns of blood pressure, but also to measure day-to-day variability and the circadian hyper-amplitude-tension, a condition in which excessive circadian BP amplitude precedes the chronic established hypertension. Our objective was to assess the 7-day/24-h circadian pattern of BP and heart rate in diabetic patients, as it could be helpful in the diagnosis and prevention of cardiovascular morbidity. Materials and Methods A total of 50 diabetic patients with type 2 diabetes and 50 non-diabetic participants were recruited for the study. General health records were individually maintained, and 7-day/24-h ambulatory blood pressure monitoring using an ambulatory blood pressure monitor was carried out. Results The rhythmic parameters of systolic and diastolic BP, heart rate, double amplitude, acrophase and 3-h fractionated hyperbaric index were found to be significantly high in diabetic patients. A total of 12 participants were diagnosed with circadian hyper-amplitude-tension. These data suggest that diabetic patients have certain variations in the circadian pattern of blood pressure and heart rate, which can result in disturbed vascular events, and thus are at greater risk of cardiovascular morbidity. Conclusion Seven-day/24-h monitoring might be useful as an early predictive tool in assessing future cardiovascular risk, guiding treatment and management of these patients. PMID:25422775

  5. Is gold solubility subject to pressure variations in ascending arc magmas?

    NASA Astrophysics Data System (ADS)

    Jégo, Sébastien; Nakamura, Michihiko; Kimura, Jun-Ichi; Iizuka, Yoshiyuki; Chang, Qing; Zellmer, Georg F.

    2016-09-01

    Magmas play a key role in the genesis of epithermal and porphyry ore deposits, notably by providing the bulk of ore metals to the hydrothermal fluid phase. It has been long shown that the formation of major deposits requires a multi-stage process, including the concentration of metals in silicate melts at depth and their transfer into the exsolved ore fluid in more superficial environments. Both aspects have been intensively studied for most of noble metals in subsurface conditions, whereas the effect of pressure on the concentration (i.e., solubility) of those metals in magmas ascending from the sublithospheric mantle to the shallow arc crust has been quite neglected. Here, we present new experimental data aiming to constrain the processes of gold (Au) dissolution in subduction-linked magmas along a range of depth. We have conducted hydrous melting experiments on two dacitic/adakitic magmas at 0.9 and 1.4 GPa and ∼1000 °C in an end-loaded piston cylinder apparatus, under fO2 conditions close to NNO as measured by solid Co-Pd-O sensors. Experimental charges were carried out in pure Au containers, the latter serving as the source of gold, in presence of variable amounts of H2O and, for half of the charges, with elemental sulfur (S) so as to reach sulfide saturation. Au concentrations in melt quenched to glass were determined by LA-ICPMS. When compared to previous data obtained at lower pressures and variable redox conditions, our results show that in both S-free and sulfide-saturated systems pressure has no direct, detectable effect on melt Au solubility. Nevertheless, pressure has a strong, negative effect on sulfur solubility. Since gold dissolution is closely related to the behavior of sulfur in reducing and moderately oxidizing conditions, pressure has therefore a significant but indirect effect on Au solubility. The present study confirms that Au dissolution is mainly controlled by fO2 in S-free melts and by a complex interplay of fO2 and melt S2

  6. TEMPORAL VARIATIONS OF X-RAY SOLAR FLARE LOOPS: LENGTH, CORPULENCE, POSITION, TEMPERATURE, PLASMA PRESSURE, AND SPECTRA

    SciTech Connect

    Jeffrey, Natasha L. S.; Kontar, Eduard P.

    2013-04-01

    The spatial and spectral properties of three solar flare coronal X-ray loops are studied before, during, and after the peak X-ray emission. Using observations from the Ramaty High Energy Solar Spectroscopic Imager (RHESSI), we deduce the temporal changes in emitting X-ray length, corpulence, volume, position, number density, and thermal pressure. We observe a decrease in the loop length, width, and volume before the X-ray peak, and an increasing number density and thermal pressure. After the X-ray peak, volume increases and loop corpulence grows due to increasing width. The volume variations are more pronounced than the position variations, often known as magnetic field line contraction. We believe this is the first dedicated study examining the temporal evolution of X-ray loop lengths and widths. Collectively, the observations also show for the first time three temporal phases given by peaks in temperature, X-ray emission, and thermal pressure, with the minimum volume coinciding with the X-ray peak. Although the volume of the flaring plasma decreases before the peak in X-ray emission, the relationship between temperature and volume does not support simple compressive heating in a collapsing magnetic trap model. Within a low {beta} plasma, shrinking loop widths perpendicular to the guiding field can be explained by squeezing the magnetic field threading the region. Plasma heating leads to chromospheric evaporation and growing number density. This produces increasing thermal pressure and decreasing loop lengths as electrons interact at shorter distances and we believe after the X-ray peak, the increasing loop corpulence.

  7. Inter- versus Intramolecular Structural Manipulation of a Dichromium(II) Pacman Complex through Pressure Variation.

    PubMed

    Stevens, Charlotte J; Prescimone, Alessandro; Tuna, Floriana; McInnes, Eric J L; Parsons, Simon; Morrison, Carole A; Arnold, Polly L; Love, Jason B

    2016-01-01

    The effect of pressure on the intranuclear M···M separation and intermolecular secondary interactions in the dinuclear chromium Pacman complex [Cr2(L)](C6H6) was evaluated because this compound contains both a short Cr···Cr separation and an exogenously bound molecule of benzene in the solid state. The electronic structure of [Cr2(L)] was determined by electron paramagnetic resonance spectroscopy, SQUID magnetometry, and density functional theory calculations and shows a diamagnetic ground state through antiferromagnetic exchange, with no evidence for a Cr-Cr bond. Analysis of the solid-state structures of [Cr2(L)](C6H6) at pressures varying from ambient to 3.0 GPa shows little deformation in the Cr···Cr separation, i.e., no Cr-Cr bond formation, but instead a significantly increased interaction between the exogenous arene and the chromium iminopyrrolide environment. It is therefore apparent from this analysis that [Cr2(L)] would be best exploited as a rigid chemical synthon, with pressure regulation being used to mediate the approach and secondary interactions of possible substrates. PMID:26683991

  8. Ultra-high temperature stability Joule-Thomson cooler with capability to accomodate pressure variations

    NASA Technical Reports Server (NTRS)

    Bard, Steven (Inventor); Wu, Jiunn-Jeng (Inventor); Trimble, Curtis A. (Inventor)

    1992-01-01

    A Joule-Thomson cryogenic refrigeration system capable of achieving high temperature stabilities in the presence of varying temperature, atmospheric pressure, and heat load is provided. The Joule-Thomson cryogenic refrigeration system includes a demand flow Joule-Thomson expansion valve disposed in a cryostat of the refrigeration system. The expansion valve has an adjustable orifice that controls the flow of compressed gas therethrough and induces cooling and partial liquefaction of the gas. A recuperative heat exchanger is disposed in the cryostat and coupled to the expansion valve. A thermostatically self-regulating mechanism is disposed in the cryostat and coupled to the J-T expansion valve. The thermostatically self-regulating mechanism automatically adjusts the cross sectional area of the adjustable valve orifice in response to environmental temperature changes and changes in power dissipated at a cold head. A temperature sensing and adjusting mechanism is coupled to a cold head for adjusting the temperature of the cold head in response to the change in heat flow in the cold head. The temperature sensing and adjusting mechanism comprises a temperature sensitive diode, a wound wire heater, and an electrical feedback control circuit coupling the diode to the heater. An absolute pressure relief valve is interposed between the output of the cryostat and an exhaust port for maintaining a constant exhaust temperature in the refrigerating system, independent of the changes in atmospheric pressure.

  9. Ultra-high temperature stability Joule-Thomson cooler with capability to accomodate pressure variations

    NASA Astrophysics Data System (ADS)

    Bard, Steven; Wu, Jiunn-Jeng; Trimble, Curtis A.

    1992-06-01

    A Joule-Thomson cryogenic refrigeration system capable of achieving high temperature stabilities in the presence of varying temperature, atmospheric pressure, and heat load is provided. The Joule-Thomson cryogenic refrigeration system includes a demand flow Joule-Thomson expansion valve disposed in a cryostat of the refrigeration system. The expansion valve has an adjustable orifice that controls the flow of compressed gas therethrough and induces cooling and partial liquefaction of the gas. A recuperative heat exchanger is disposed in the cryostat and coupled to the expansion valve. A thermostatically self-regulating mechanism is disposed in the cryostat and coupled to the J-T expansion valve. The thermostatically self-regulating mechanism automatically adjusts the cross sectional area of the adjustable valve orifice in response to environmental temperature changes and changes in power dissipated at a cold head. A temperature sensing and adjusting mechanism is coupled to a cold head for adjusting the temperature of the cold head in response to the change in heat flow in the cold head. The temperature sensing and adjusting mechanism comprises a temperature sensitive diode, a wound wire heater, and an electrical feedback control circuit coupling the diode to the heater. An absolute pressure relief valve is interposed between the output of the cryostat and an exhaust port for maintaining a constant exhaust temperature in the refrigerating system, independent of the changes in atmospheric pressure.

  10. Impact of Wall Shear Stress and Pressure Variation on the Stability of Atherosclerotic Plaque

    NASA Astrophysics Data System (ADS)

    Taviani, V.; Li, Z. Y.; Sutcliffe, M.; Gillard, J.

    Rupture of vulnerable atheromatous plaque in the carotid and coronary arteries often leads to stroke and heart attack respectively. The mechanism of blood flow and plaque rupture in stenotic arteries is still not fully understood. A three dimensional rigid wall model was solved under steady and unsteady conditions assuming a time-varying inlet velocity profile to investigate the relative importance of axial forces and pressure drops in arteries with asymmetric stenosis. Flow-structure interactions were investigated for the same geometry and the results were compared with those retrieved with the corresponding one dimensional models. The Navier-Stokes equations were used as the governing equations for the fluid. The tube wall was assumed linearly elastic, homogeneous isotropic. The analysis showed that wall shear stress is small (less than 3.5%) with respect to pressure drop throughout the cycle even for severe stenosis. On the contrary, the three dimensional behavior of velocity, pressure and wall shear stress is in general very different from that predicted by one dimensional models. This suggests that the primary source of mistakes in one dimensional studies comes from neglecting the three dimensional geometry of the plaque. Neglecting axial forces only involves minor errors.

  11. A quantitative analysis of the effects of activity and time of day on the diurnal variations of blood pressure.

    PubMed

    Clark, L A; Denby, L; Pregibon, D; Harshfield, G A; Pickering, T G; Blank, S; Laragh, J H

    1987-01-01

    The effects of activity and time of day on blood pressure (BP) were analyzed in 461 patients with untreated hypertension who wore a noninvasive portable BP recorder which took readings every 15 minutes for 24 hours. Patients recorded activity and location in a diary. The data were analyzed separately for two groups of patients: the 190 who stayed at home and the 271 who went to work. The effects of 16 different activities on BP were estimated by relating the BP to the associated activity and to the individual's clinic BP. Blood pressure was higher at work than at home, but the increment of BP for individual activities was similar in the two locations. The overall effect of activities on BP variability was computed using a one-way analysis of covariance model. For the patients who went to work this model accounted for 40% of the observed variation (R2) for systolic and 39% for diastolic BP. A similar model using time of day instead of activity accounted for 33% of variability in both systolic and diastolic BP. Combining activity and time of day was little better than activity alone (41% for both). After allowing for the effects of activity on BP, where sleep is one of the activities, there was no significant diurnal variation of BP. We conclude that there is no important circadian rhythm of BP which is independent of activity. PMID:3597670

  12. Geographic variation in host-specificity and parasitoid pressure of an herbivore (geometridae) associated with the tropical genus piper (piperaceae).

    PubMed

    Connahs, Heidi; Rodríguez-Castañeda, Genoveva; Walters, Toni; Walla, Thomas; Dyer, Lee

    2009-01-01

    The extraordinary diversity of tropical herbivores may be linked to hostplant specialization driven in part by variation in pressure from natural enemies. We quantified levels of host-specificity and parasitoid attack for the specialist herbivore, Eois (Geometridae). The goals of this research were to examine: 1) whether Eois are specialized on the genus Piper (Piperaceae) and if hostplant specialization varies geographically; 2) whether Eois are equally vulnerable to parasitoid attack across different geographic regions and by the same parasitoid families; and 3) whether parasitism levels vary with precipitation and elevation. Based on over 15,000 rearings, we found Eois caterpillars feeding exclusively on Piper. However, we did not detect geographic differences in host-specificity; each Eois species fed on an average of two Piper species. Parasitism levels of Eois varied significantly with climate and topography; Eois were most vulnerable to parasitoid attack in moist versus dry and wet forests and at low versus high elevations. The diversity of parasitoid families reared from Eois was greater in Ecuador and Costa Rica than in Panama, where parasitoids were primarily in the family Braconidae. The quantitative evidence for host-specificity provides support for the hypothesis that Eois are specialized on Piper. Our results also reveal that Eois are exposed to a mosaic of potential selective pressures due to variation in parasitoid attack over a large spatial scale. PMID:19613860

  13. Molecular-structure variation of organic materials irradiated with atmospheric pressure plasma

    NASA Astrophysics Data System (ADS)

    Takenaka, K.; Miyazaki, A.; Setsuhara, Y.

    2014-06-01

    The effect of atmospheric pressure He plasma on the molecular structure of polyethylene terephthalate (PET) has been investigated. The plasma composition was analyzed using optical emission spectroscopy. In addition to strong He emission lines, lines due to O and N radicals were also detected. The change in the molecular structure of the PET film surface was investigated using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. It was found that plasma irradiation led to oxidation and degradation of the surface due to chemical and physical effects of the active species. The results demonstrate the feasibility of observing the interaction of plasma with organic material on a local scale.

  14. Pore water pressure variations in Subpermafrost groundwater : Numerical modeling compared with experimental modeling

    NASA Astrophysics Data System (ADS)

    Rivière, Agnès.; Goncalves, Julio; Jost, Anne; Font, Marianne

    2010-05-01

    Development and degradation of permafrost directly affect numerous hydrogeological processes such as thermal regime, exchange between river and groundwater, groundwater flows patterns and groundwater recharge (Michel, 1994). Groundwater in permafrost area is subdivided into two zones: suprapermafrost and subpermafrost which are separated by permafrost. As a result of the volumetric expansion of water upon freezing and assuming ice lenses and frost heave do not form freezing in a saturated aquifer, the progressive formation of permafrost leads to the pressurization of the subpermafrost groundwater (Wang, 2006). Therefore disappearance or aggradation of permafrost modifies the confined or unconfined state of subpermafrost groundwater. Our study focuses on modifications of pore water pressure of subpermafrost groundwater which could appear during thawing and freezing of soil. Numerical simulation allows elucidation of some of these processes. Our numerical model accounts for phase changes for coupled heat transport and variably saturated flow involving cycles of freezing and thawing. The flow model is a combination of a one-dimensional channel flow model which uses Manning-Strickler equation and a two-dimensional vertically groundwater flow model using Richards equation. Numerical simulation of heat transport consisted in a two dimensional model accounting for the effects of latent heat of phase change of water associated with melting/freezing cycles which incorporated the advection-diffusion equation describing heat-transfer in porous media. The change of hydraulic conductivity and thermal conductivity are considered by our numerical model. The model was evaluated by comparing predictions with data from laboratory freezing experiments. Experimental design was undertaken at the Laboratory M2C (Univesité de Caen-Basse Normandie, CNRS, France). The device consisted of a Plexiglas box insulated on all sides except on the top. Precipitation and ambient temperature are

  15. SEASONAL MORTALITY PATTERNS IN NON-HUMAN PRIMATES: IMPLICATIONS FOR VARIATION IN SELECTION PRESSURES ACROSS ENVIRONMENTS

    PubMed Central

    Gogarten, Jan F.; Brown, Leone M.; Chapman, Colin A.; Cords, Marina; Doran-Sheehy, Diane; Fedigan, Linda M.; Grine, Frederick E.; Perry, Susan; Pusey, Anne E.; Sterck, Elisabeth H. M.; Wich, Serge A.; Wright, Patricia C.

    2014-01-01

    Examining seasonal mortality patterns can yield insights into the drivers of mortality and thus potential selection pressures acting on individuals in different environments. We compiled adult and juvenile mortality data from nine wild non-human primate taxa to investigate the role of seasonality in patterns of mortality and address the following questions: Is mortality highly seasonal across species? Does greater environmental seasonality lead to more seasonal mortality patterns? If mortality is seasonal, is it higher during wet seasons or during periods of food scarcity? and Do folivores show less seasonal mortality than frugivores? We found seasonal mortality patterns in five of nine taxa, and mortality was more often tied to wet seasons than food-scarce periods, a relationship that may be driven by disease. Controlling for phylogeny, we found a positive relationship between the degree of environmental seasonality and mortality, with folivores exhibiting more seasonal mortality than frugivores. These results suggest that mortality patterns are influenced both by diet and degree of environmental seasonality. Applied to a wider array of taxa, analyses of seasonal mortality patterns may aid understanding of life-history evolution and selection pressures acting across a broad spectrum of environments and spatial and temporal scales. PMID:23025613

  16. Results of epidemiological studies of blood pressure are biased by continuous variation in arm size related to body mass.

    PubMed

    Ulijaszek, Stanley J; Henneberg, Maciej

    2012-08-01

    In cross-sectional epidemiological studies, blood pressure (BP) is often found to be positively correlated with fatness. Usually sphygmomanometers with only one cuff size for adults are used to measure BP while arm circumference (AC) influences BP readings. We have studied cross-sectional anthropometric and BP data of adult men and women from three populations: Cook Islanders (n = 259), Papua New Guinean: Purari (n = 295), and Ok Tedi (n = 274). These were selected because of their diverse socio-economic, anthropometric, and BP characteristics. Partial correlations and regressions were used to analyze these data. Systolic and diastolic pressures (SBP, DBP) showed dependence on AC, body mass index (BMI), and skinfold thickness. Stature had some effect on SBP and DBP, independent of BMI and AC. When effects of AC and stature were statistically controlled, BMI did not correlate with either SBP or DBP. People of larger body mass have greater AC, and this biases BP readings. Average values of SBP and DBP in groups of underweight, normal, overweight, and obese people predicted by AC (sex, age, and BMI being statistically controlled) closely matched observed SBP and DBP averages in those groups. Out of 24 pairwise comparisons (3 samples from different populations × 4 groups of BMI × 2 pressure readings) of predicted and actual BP, only two produced statistically significant differences while 21 of the differences were 5 mm Hg or less. Correlations between BP and obesity found in epidemiological studies may be severely biased by effects of variation in AC. Sphygmomanometric measurements of BP should be corrected for continuous variation in AC. PMID:23249317

  17. SIRT1 Polymorphisms Associate with Seasonal Weight Variation, Depressive Disorders, and Diastolic Blood Pressure in the General Population

    PubMed Central

    Kovanen, Leena; Donner, Kati; Partonen, Timo

    2015-01-01

    SIRT1 polymorphisms have previously been associated with depressive and anxiety disorders. We aimed at confirming these earlier findings and extending the analyses to seasonal variations in mood and behavior. Three tag single-nucleotide polymorphisms (SNPs) were selected to capture the common variation in the SIRT1 gene. 5910 individuals (with blood sample, diagnostic interview, self-report of on seasonal changes in mood and behavior) were selected from a representative Finnish nationwide population-based sample. Logistic and linear regression models were used to analyze the associations between the SNPs and depressive and anxiety disorders, metabolic syndrome (EGIR criteria) and its components, and health examination measurements, Homeostasis Model Assessments, and diagnoses of type 2 and type 1 diabetes. SIRT1 rs2273773 showed evidence of association with seasonal variation in weight (C-allele, OR = 0.85, 95% CI = 0.76–0.95, p = 0.005). In addition, our study gave further support for the association of SIRT1 gene with depressive disorders (rs3758391) and diastolic blood pressure (rs2273773). PMID:26509718

  18. Identification of the characteristics of motorcycle and scooter tyres in the presence of large variations in inflation pressure

    NASA Astrophysics Data System (ADS)

    Cossalter, V.; Doria, A.; Giolo, E.; Taraborrelli, L.; Massaro, M.

    2014-10-01

    Stability and safety of road vehicles are largely affected by tyre properties. Single-track vehicles are characterised by weakly damped modes of vibration (weave and wobble) and therefore this phenomenon is even more important. This article focuses on the study of both steady-state and transient properties of motorcycle and scooter tyres in the presence of very low and very high inflation pressures. The steady-state properties are defined as lateral forces (side-slip and camber forces) and yaw torques (self-aligning and twisting). The transient properties are described in terms of relaxation length, which represents the distance needed to reach a certain percentage of the steady-state value of the tyre force. Experimental tests are carried out on a specific rotating disk machine. Three sets of tyres are analysed. Steady-state properties are measured by increasing step by step the values of camber and side-slip angles. Transient properties are studied carrying out tests with harmonic side-slip excitation and measuring the phase lag between the excitation (input) and the tyre force (output). Experimental results show important variations in tyre properties with inflation pressure with general trends of all the tested tyres and particular features related to the tyre's geometry. After the analysis and discussion of experimental results, the measured data are fitted by means of a specific version of the Magic Formula. The dependence of the Magic Formula's coefficients on inflation pressure is analysed and interpolation curves are given.

  19. Experimental Study and Analytical Methods for Particle Bed Dryout With Heterogeneous Particles and Pressure Variation

    SciTech Connect

    Miettinen, Jaakko; Sairanen, Risto; Lindholm, Ilona; Holmstrom, Stefan

    2002-07-01

    The interest to study the dryout heat flux in particle beds is related to interest of quantify the debris coolability margins during a hypothetical severe reactor accident. When the molten core has relocated to the containment floor, one accident management concept is based on the cooling of the corium by the water injection on top. Earlier experimental and analytical work has concentrated on homogeneous particle beds at atmospheric pressures. For plant safety assessment in Finland, there is a need to consider heterogeneous particle mixtures, layered particle bed setups and varied pressures. A facility has been constructed at VTT to measure dryout heat flux in a heterogeneous particle bed. The bed dimensions are 0.3 m in diameter and 0.6 m in height, with a mixture of 0.1 to 10 mm particles. The facility has a pressure range from atmospheric to 6 bar (overpressure). The bed is heated by spirals of a resistance band. The preliminary experiments have been carried out, but a more systematic set of data is expected to be available in the spring 2002. To support the experiments analytical models have been developed for qualification of the experimental results. The first comparison is done against various critical heat flux correlations developed in 1980's and 1990's for homogeneous bed conditions. The second comparison is done against 1-D and 0-D models developed by Lipinski. The most detailed analysis of the transient process conditions and dryout predictions are done by using the two-dimensional, drift-flux based thermohydraulic solution for the particle bed immersed into the water. The code is called PILEXP. Already the first validation results against the preliminary tests indicate that the transient process conditions and the mechanisms related to the dryout can be best explained and understood by using a multidimensional, transient code, where all details of the process control can be modeled as well. The heterogeneous bed and stratified bed can not be well

  20. Variation in polydispersity in pump- and pressure-driven micro-droplet generators

    NASA Astrophysics Data System (ADS)

    Zeng, Wen; Jacobi, Ian; Li, Songjing; Stone, Howard A.

    2015-11-01

    The polydispersity of droplets produced in a typical T-junction microfluidic channel under both syringe-pump-driven and pressure-driven flow configurations is measured quantitatively. Both flow systems exhibit high-frequency flow fluctuations that result in an intrinsic polydispersity due to the mechanism of droplet generation. In addition to this intrinsic polydispersity, the syringe-pump-driven device also exhibits low-frequency fluctuations due to mechanical oscillations of the pump, which overwhelm the high-frequency flow fluctuations and produce a signficantly heightened level of polydispersity. The quantitative difference in polydispersity between the two configurations and time-resolved measurements of individual droplet sizes are presented in order to enable the design of better flow control systems for droplet production.

  1. Seasonal Variation in Blood Pressure in 162,135 Patients With Type 1 or Type 2 Diabetes Mellitus.

    PubMed

    Hermann, Julia M; Rosenbauer, Joachim; Dost, Axel; Steigleder-Schweiger, Claudia; Kiess, Wieland; Schöfl, Christof; Holl, Reinhard W

    2016-04-01

    Seasonal variation in blood pressure (BP) has been observed in different populations. However, only few studies have focused on BP seasonality in diabetic patients. This study examined the seasonal patterns in BP in 62,589 patients with type 1 diabetes mellitus (T1DM) and in 99,546 patients with type 2 diabetes mellitus (T2DM) from the German/Austrian Diabetes Follow-up Registry. Adjusted mean BP values revealed seasonal cycles of 12 months, with higher BP in colder months. Using harmonic regression models, the estimated systolic BP difference throughout the year was 2.28/2.48 mm Hg in T1DM/T2DM (both P<.001). Interestingly, seasonal variation in diastolic BP was larger in T1DM than in T2DM (1.24/0.64 mm Hg, P<.001). A sex difference was observed in T1DM only, while age differences occurred in both types of diabetes. Correlations between BP and potentially related factors such as outdoor temperature indicated that reasons underlying BP seasonality are likely to be complex and vary by subgroup. PMID:26663673

  2. Large-scale tectonic features induced by mantle avalanches with phase, temperature, and pressure lateral variations of viscosity

    NASA Astrophysics Data System (ADS)

    Brunei, David; Machetel, Philippe

    1998-03-01

    A more general expression for the mantle vorticity equation is proposed for convection using axisymmetrical spherical geometry. Both the main mantle phase changes and radial and lateral variations of viscosity due to temperature and pressure. Four series of computations have been performed with (1) both the latent heat releases of the 400 km exothermic and the 670 km endothermic phase change and uniform and constant mantle viscosity; (2) the 670 km phase change alone and viscosity jumps of 10 or 30 between upper and lower mantle phases; (3) the 670 km endothermic phase change, a viscosity contrast of 30, and temperature and pressure dependent viscosity law; and (4) both 400 km and 670 km phase changes, a viscosity jump of 30, and a temperature and pressure dependent viscosity. The 400 km exothermic phase change modifies the global structure from partly layered to whole mantle convection. This effect is opposite to the effect obtained by increasing the viscosity jump at 670 km. However, both effects induce unrealistic thermal behavior which will not appear with temperature dependent laws for viscosity. The mantle avalanches which suddenly inject huge quantities of cold material into the lower mantle have effects at the surface and at the core-mantle boundary (CMB). They induced heat flow crises which explain the huge volcanic events, high rates of mid-oceanic ridge accretion, and periods of low-frequency magnetic reversal. The surface heat flow proceeds directly from the upper mantle return flow along with the avalanches. The temperature dependent viscosity tends to decrease the strength of the avalanches. The bottom heat flow and the birth of CMB plumes may be considered as the consequences of cold upper mantle material arrival at the CMB. The lower mantle and the upper mantle transit times depend on the thickness of upper and lower mantles but also on the phase changes and on the viscosity. The CMB and surface perturbations may be simultaneous (to a few tens of

  3. Experimental and analytical investigation of the variation of spray characteristics along a radial distance downstream of a pressure-swirl atomizer

    NASA Technical Reports Server (NTRS)

    Chin, J. S.; Li, W. M.; Wang, X. F.

    1986-01-01

    The variation of spray characteristics along a radial distance downstream of a pressure-swirl atomizer was measured by laser light-scattering technology. An analytical model was developed to predict the variation of spray characteristics along the radial distance. A comparison of the predicted and experimental data showed excellent agreement. Therefore, the spray model proposed, although relatively simple, is correct and can be used, with some expansion and modification of the prepared model, to predict more complicated spray systems.

  4. Automated stroke volume and pulse pressure variations predict fluid responsiveness in mechanically ventilated patients with obstructive jaundice

    PubMed Central

    Zhao, Feng; Wang, Peng; Pei, Shujun; Mi, Weidong; Fu, Qiang

    2015-01-01

    Background and objectives: Stroke volume variation (SVV) and the pulse pressure variation (PPV) have been found to be effective in prediction fluid responsiveness especially in high risk operations. The objective of this study is to validate the ability of SVV obtained by FloTrac/Vigileo system and PPV obtained by IntelliVue MP System to predict fluid responsiveness in patients with obstructive jaundice during mechanical ventilation. Methods: Twentyfive patients with obstructive jaundice (mean serum total bilirubin 175.0 ± 120.8 μmol/L), who accepted volume expansion and were hemodynamically stable after induction of anesthesia, were included in the study. SVV and PPV were recorded simultaneously before and after an intravascular volume expansion. Patients with a stroke volume index (SVI) increase of more than 10% after volume expansion were considered as responders. Results: The agreement (mean bias ± SD) between SVV and PPV was -0.2% ± 1.56%. Before volume expansion, SVV and PPV were significantly higher in responders compared to non-responders (P<0.001, P<0.001). Significant correlation was observed between the baseline value of SVV and PPV and the percent change in SVI after fluid expansion (r=0.654, P<0.001; r=0.592, P=0.002). Area under the receiver operating characteristic curves of SVV (0.955) and PPV (0.875) were comparable (P=0.09). The optimal threshold values in predicting fluid responsiveness were 10% for SVV and 8% for PPV. Conclusion: In conclusion, SVV obtained by FloTrac/Vigileo system and PPV obtained by IntelliVue MP System was able to predict fluid responsiveness in patients with obstructive jaundice. PMID:26884998

  5. Correlation of the ratio of caudal vena cava diameter and aorta diameter with systolic pressure variation in anesthetized dogs.

    PubMed

    Meneghini, Caterina; Rabozzi, Roberto; Franci, Paolo

    2016-02-01

    OBJECTIVE To evaluate the correlation coefficient of the ratio between diameter of the caudal vena cava (CVC) and diameter of the aorta (Ao) in dogs as determined ultrasonographically with systolic pressure variation (SPV). ANIMALS 14 client-owned dogs (9 females and 5 males; mean ± SD age, 73 ± 40 months; mean body weight, 22 ± 7 kg) that underwent anesthesia for repair of skin wounds. PROCEDURES Anesthesia was induced. Controlled mechanical ventilation with a peak inspiratory pressure of 8 cm H2O was immediately started, and SPV was measured. During a brief period of suspension of ventilation, CVC-to-Ao ratio was measured on a transverse right-lateral intercostal ultrasonographic image obtained at the level of the porta hepatis. When the SPV was ≥ 4 mm Hg, at least 1 bolus (3 to 4 mL/kg) of Hartmann solution was administered IV during a 1-minute period. Bolus administration was stopped and the CVC-to-Ao ratio measured when SPV was < 4 mm Hg. Correlation coefficient analysis was performed. RESULTS 28 measurements were obtained. The correlation coefficient was 0.86 (95% confidence interval, 0.72 to 0.93). Mean ± SD SPV and CVC-to-Ao ratio before bolus administration were 7 ± 2 mm Hg and 0.52 ± 0.16, respectively. Mean ± SD SPV and CVC-to-Ao ratio after bolus administration were 2 ± 0.6 mm Hg and 0.91 ± 0.13, respectively. CONCLUSIONS AND CLINICAL RELEVANCE In this study, the CVC-to-Ao ratio was a feasible, noninvasive ultrasonographically determined value that correlated well with SPV. (Am J Vet Res 2016;77:137-143). PMID:27027706

  6. Single-shot temperature- and pressure-sensitive paint measurements on an unsteady helicopter blade

    NASA Astrophysics Data System (ADS)

    Disotell, Kevin J.; Peng, Di; Juliano, Thomas J.; Gregory, James W.; Crafton, Jim W.; Komerath, Narayanan M.

    2014-02-01

    Unsteady pressure-sensitive paint (PSP) measurements were acquired on an articulated model helicopter rotor of 0.26 m diameter in edgewise flow to simulate forward flight conditions. The rotor was operated at advance ratios (free stream velocity normalized by hover tip speed) of 0.15 and 0.30 at a cycle-averaged tip chord Reynolds number of 1.1 × 105, with collective and longitudinal cyclic pitch inputs of 10° and 2.5°, respectively. A single-shot data acquisition technique allowed a camera to record the paint luminescence after a single pulse of high-energy laser excitation, yielding sufficient signal-to-noise ratio to avoid image averaging. Platinum tetra(pentafluorophenyl) porphyrin (PtTFPP) in a porous polymer/ceramic binder served as the PSP. To address errors caused by image blurring and temperature sensitivity, a previously reported motion deblurring algorithm was implemented and the temperature correction was made using temperature-sensitive paint measurements on a second rotor blade. Instantaneous, unsteady surface pressure maps at a rotation rate of 82 Hz captured different aerodynamic responses between the two sides of the rotor disk and were compared to the nominally steady hover case. Cycle-to-cycle variations in tip unsteadiness on the retreating blade were also observed, causing oblique pressure features which may be linked to three-dimensional stall.

  7. Seasonal Variations in the CO Line Profile and the Retrieved Thermal/Pressure Structures in the Atmosphere of Mars

    NASA Astrophysics Data System (ADS)

    Khayat, Alain; Villanueva, G. L.; Mumma, M. J.; Riesen, T. E.; Tokunaga, A. T.

    2013-10-01

    We report retrievals of temperature vertical profiles up to 100 km over Tharsis and Syrtis regions on Mars obtained by inverting the strong rotational (3-2) line of carbon monoxide (CO) at 346 GHz. Observations of CO were made from mid Northern Spring to early Northern Summer on Mars (Ls= 36°-108°, 23 Nov, 2011 - 13 May, 2012) using the Caltech Submillimeter Observatory's (CSO) high-resolution heterodyne receiver (Barney) on top of Mauna Kea, Hawai'i. The temperature profiles were derived using our radiative transfer model that considers the latest spectroscopic constants for CO collisionally broadened by CO2. We observe notable changes of the line profile for different dates, which are directly related to seasonal variations in the thermal/pressure structure of the atmosphere. The seasonal variability of the martian CO line profile, the extracted temperature profiles, and comparisons with modeled profiles from the Mars Climate Database (Lewis et al, 1999) will be presented. We gratefully acknowledge support from the NASA Planetary Astronomy Program , NASA Astrobiology Institute, Planetary Atmospheres programs. This material is based upon work at the Caltech Submillimeter Observatory, which is operated by the California Institute of Technology under cooperative agreement with the National Science Foundation, grant number AST-0838261.

  8. Intraoperative monitoring of stroke volume variation versus central venous pressure in laparoscopic liver surgery: a randomized prospective comparative trial☆

    PubMed Central

    Ratti, Francesca; Cipriani, Federica; Reineke, Raffaella; Catena, Marco; Paganelli, Michele; Comotti, Laura; Beretta, Luigi; Aldrighetti, Luca

    2015-01-01

    Background Central venous pressure (CVP) is used as a marker of cardiac preload to control intraoperative blood loss in open hepatectomies, while its reliability in laparoscopy is less certain. The aim of this randomized prospective trial was to evaluate the outcome of laparoscopic resections performed with stroke volume variation (SVV) or CVP monitoring. Methods All candidates for laparoscopic liver resection were assigned randomly to SVV or to CVP groups. Outcome was evaluated included conversion rate, cause of conversion, intraoperative blood loss, need for transfusions, length of surgery and postoperative results. Results Ninety consecutive patients were enrolled: both SVV and CVP groups included 45 patients each and were comparable in terms of patient and disease characteristics. A reduced rate of conversion was recorded in the SVV compared to the CVP group (6.7% and 17.8% respectively, p = 0.02). Blood loss was lower in the SVV group (150 mL), compared to the CVP group (300 mL, p = 0.04). Morbidity, mortality, length of stay and functional recovery were comparable. On multivariate analysis, lesion location, extent of hepatectomy and type of cardiac preload monitoring were associated significantly to risk of conversion. Conclusion SVV monitoring in laparoscopic liver surgery improves intraoperative outcome, thus enhancing the benefits of the minimally-invasive approach and fast-track protocols. PMID:26902132

  9. Applicability of Pulse Pressure Variation during Unstable Hemodynamic Events in the Intensive Care Unit: A Five-Day Prospective Multicenter Study.

    PubMed

    Delannoy, Bertrand; Wallet, Florent; Maucort-Boulch, Delphine; Page, Mathieu; Kaaki, Mahmoud; Schoeffler, Mathieu; Alexander, Brenton; Desebbe, Olivier

    2016-01-01

    Pulse pressure variation can predict fluid responsiveness in strict applicability conditions. The purpose of this study was to describe the clinical applicability of pulse pressure variation during episodes of patient hemodynamic instability in the intensive care unit. We conducted a five-day, seven-center prospective study that included patients presenting with an unstable hemodynamic event. The six predefined inclusion criteria for pulse pressure variation applicability were as follows: mechanical ventilation, tidal volume >7 mL/kg, sinus rhythm, no spontaneous breath, heart rate/respiratory rate ratio >3.6, absence of right ventricular dysfunction, or severe valvulopathy. Seventy-three patients presented at least one unstable hemodynamic event, with a total of 163 unstable hemodynamic events. The six predefined criteria for the applicability of pulse pressure variation were completely present in only 7% of these. This data indicates that PPV should only be used alongside a strong understanding of the relevant physiology and applicability criteria. Although these exclusion criteria appear to be profound, they likely represent an absolute contraindication of use for only a minority of critical care patients. PMID:27127648

  10. Applicability of Pulse Pressure Variation during Unstable Hemodynamic Events in the Intensive Care Unit: A Five-Day Prospective Multicenter Study

    PubMed Central

    Delannoy, Bertrand; Wallet, Florent; Maucort-Boulch, Delphine; Page, Mathieu; Kaaki, Mahmoud; Schoeffler, Mathieu; Alexander, Brenton; Desebbe, Olivier

    2016-01-01

    Pulse pressure variation can predict fluid responsiveness in strict applicability conditions. The purpose of this study was to describe the clinical applicability of pulse pressure variation during episodes of patient hemodynamic instability in the intensive care unit. We conducted a five-day, seven-center prospective study that included patients presenting with an unstable hemodynamic event. The six predefined inclusion criteria for pulse pressure variation applicability were as follows: mechanical ventilation, tidal volume >7 mL/kg, sinus rhythm, no spontaneous breath, heart rate/respiratory rate ratio >3.6, absence of right ventricular dysfunction, or severe valvulopathy. Seventy-three patients presented at least one unstable hemodynamic event, with a total of 163 unstable hemodynamic events. The six predefined criteria for the applicability of pulse pressure variation were completely present in only 7% of these. This data indicates that PPV should only be used alongside a strong understanding of the relevant physiology and applicability criteria. Although these exclusion criteria appear to be profound, they likely represent an absolute contraindication of use for only a minority of critical care patients. PMID:27127648

  11. Magnitude of long-term non-lithostatic pressure variations in lithospheric processes: insight from thermo-mechanical subduction/collision models

    NASA Astrophysics Data System (ADS)

    Gerya, Taras

    2014-05-01

    On the one hand, the principle of lithostatic pressure is habitually used in metamorphic geology to calculate paleo-depths of metamorphism from mineralogical pressure estimates given by geobarometry. On the other hand, it is obvious that this lithostatic (hydrostatic) pressure principle should only be valid for an ideal case of negligible deviatoric stresses during the long-term development of the entire tectono-metamorphic system - the situation, which newer comes to existence in natural lithospheric processes. The question is therefore not "Do non-lithostatic pressure variations exist?" but " What is the magnitude of long-term non-lithostatic pressure variations in various lithospheric processes, which can be recorded by mineral equilibria of respective metamorphic rocks?". The later question is, in particular, relevant for various types of high-pressure (HP) and ultrahigh-pressure (UHP) rocks, which are often produced in convergent plate boundary settings (e.g., Hacker and Gerya, 2013). This question, can, in particular, be answered with the use of thermo-mechanical models of subduction/collision processes employing realistic P-T-stress-dependent visco-elasto-brittle/plastic rheology of rocks. These models suggest that magnitudes of pressure deviations from lithostatic values can range >50% underpressure to >100% overpressure, mainly in the regions of bending of rheologically strong mantle lithosphere (Burg and Gerya, 2005; Li et al., 2010). In particular, strong undepresures along normal faults forming within outer rise regions of subducting plates can be responsible for downward water suction and deep hydration of oceanic slabs (Faccenda et al., 2009). Weaker HP and UHP rocks of subduction/collision channels are typically subjected to lesser non-lithostatic pressure variations with characteristic magnitudes ranging within 10-20% from the lithostatic values (Burg and Gerya, 2005; Li et al., 2010). The strength of subducted crustal rocks and the degree of

  12. Gravimetric phenotyping of whole plant transpiration responses to atmospheric vapour pressure deficit identifies genotypic variation in water use efficiency.

    PubMed

    Ryan, Annette C; Dodd, Ian C; Rothwell, Shane A; Jones, Ros; Tardieu, Francois; Draye, Xavier; Davies, William J

    2016-10-01

    There is increasing interest in rapidly identifying genotypes with improved water use efficiency, exemplified by the development of whole plant phenotyping platforms that automatically measure plant growth and water use. Transpirational responses to atmospheric vapour pressure deficit (VPD) and whole plant water use efficiency (WUE, defined as the accumulation of above ground biomass per unit of water used) were measured in 100 maize (Zea mays L.) genotypes. Using a glasshouse based phenotyping platform with naturally varying VPD (1.5-3.8kPa), a 2-fold variation in WUE was identified in well-watered plants. Regression analysis of transpiration versus VPD under these conditions, and subsequent whole plant gas exchange at imposed VPDs (0.8-3.4kPa) showed identical responses in specific genotypes. Genotype response of transpiration versus VPD fell into two categories: 1) a linear increase in transpiration rate with VPD with low (high WUE) or high (low WUE) transpiration rate at all VPDs, 2) a non-linear response with a pronounced change point at low VPD (high WUE) or high VPD (low WUE). In the latter group, high WUE genotypes required a significantly lower VPD before transpiration was restricted, and had a significantly lower rate of transpiration in response to VPD after this point, when compared to low WUE genotypes. Change point values were significantly positively correlated with stomatal sensitivity to VPD. A change point in stomatal response to VPD may explain why some genotypes show contradictory WUE rankings according to whether they are measured under glasshouse or field conditions. Furthermore, this novel use of a high throughput phenotyping platform successfully reproduced the gas exchange responses of individuals measured in whole plant chambers, accelerating the identification of plants with high WUE. PMID:27593468

  13. Outcomes associated with stroke volume variation versus central venous pressure guided fluid replacements during major abdominal surgery

    PubMed Central

    Kumar, Lakshmi; Rajan, Sunil; Baalachandran, Ramasubramanian

    2016-01-01

    Background and Aims: There is limited data on the impact of perioperative fluid therapy guided by dynamic preload variables like stroke volume variation (SVV) on outcomes after abdominal surgery. We studied the effect of SVV guided versus central venous pressure (CVP) guided perioperative fluid administration on outcomes after major abdominal surgery. Material and Methods: Sixty patients undergoing major abdominal surgeries were randomized into two equal groups in this prospective single blind randomized study. In the standard care group, the CVP was maintained at 10-12 mmHg while in the intervention group a SVV of 10% was achieved by the administration of fluids. The primary end-points were the length of Intensive Care Unit (ICU) and hospital stay. The secondary end points were intraoperative lactate, intravenous fluid use, requirement for inotropes, postoperative ventilation and return of bowel function. Results: The ICU stay was significantly shorter in the intervention group as compared to the control group (2.9 ± 1.15 vs. 5.4 ± 2.71 days). The length of hospital stay was also shorter in the intervention group, (9.9 ± 2.68 vs. 11.96 ± 5.15 days) though not statistically significant. The use of intraoperative fluids was significantly lower in the intervention group than the control group (7721.5 ± 4138.9 vs. 9216.33 ± 2821.38 ml). Other secondary outcomes were comparable between the two groups. Conclusion: Implementation of fluid replacement guided by a dynamic preload variable (SVV) versus conventional static variables (CVP) is associated with lesser postoperative ICU stay and reduced fluid requirements in major abdominal surgery.

  14. Relationship between Ocean Bottom Pressure Variations and Baroclinic Eddy off Kushiro-Tokachi from 2004 to 2013

    NASA Astrophysics Data System (ADS)

    Hasegawa, Takuya; Nagano, Akira; Matsumoto, Hiroyuki; Ariyoshi, Keisuke

    2016-04-01

    The scope of this study is to explore relationships between ocean bottom pressure (OBP) variations related to ocean plate changes, and oceanic climate changes like El Nino/Southern Oscillation (ENSO). We analyzed OBP data at stations PG1 (41.7040N-144.4375E) and PG2 (42.2365N-144.8454E) obtained from the Long-Term Deep Sea Floor Observatory off Kushiro-Tokachi in the Kuril Trench, gridded daily sea surface height (SSH) data provided by AVISO, and conductivity-temperature-depth (CTD) data at a repeated observation line off Akkeshi (A-line) from 2004 to 2013. In addition, we used Nino-3 index, which is one of the major indices for ENSO and is given by the CPC/NOAA. It is suggested that SSH at PG1 and PG2 similarly vary affected by the Oyashio, the western boundary current of the North Pacific subarctic gyre, and El Nino events in 2006 and 2007 via atmospheric telconnections. OBP time series at PG1 and PG2 are almost in phase in most of the analysis period, but from the early 2006 to the end of 2007, are quit discrepant in amplitude; at that occasion, OBP at PG1 is much higher than that at PG2. Expecting a peculiar hydrographic feature at the occasion, CTD data along the A-line in January 2007 are analyzed. A lenticular eddy was found to exist in a layer between 1500 and 3000 dbar and to deepen substantially isopycnals of approximately 27.7 sigma-theta around a depth of 2000 dbar. Probably due to the baroclinic eddy feature, OBP is kept low at PG2, while high at PG1. The subthermocline water occupying the deep eddy are considered not to be originated in the North Pacific but to be derived from the Southern Ocean.

  15. Variation of Pressure with Depth of Water: Working with High-Tech and Low-Cost Materials

    ERIC Educational Resources Information Center

    Ornek, Funda; Zziwa, Byansi Jude; Taganahan, Teresita D.

    2013-01-01

    When you dive underwater, you feel the pressure on your ears and, as you dive deeper, more pressure is felt. This article presents an activity that teachers might find useful for demonstrating the relationship between water depth and pressure. (Contains 5 figures and 1 table.)

  16. Pressure variation of Rashba spin splitting toward topological transition in the polar semiconductor BiTeI

    NASA Astrophysics Data System (ADS)

    Ideue, T.; Checkelsky, J. G.; Bahramy, M. S.; Murakawa, H.; Kaneko, Y.; Nagaosa, N.; Tokura, Y.

    2014-10-01

    BiTeI is a polar semiconductor with gigantic Rashba spin-split bands in bulk. We have investigated the effect of pressure on the electronic structure of this material via magnetotransport. Periods of Shubunikov-de Haas (SdH) oscillations originating from the spin-split outer Fermi surface and inner Fermi surface show disparate responses to pressure, while the carrier number derived from the Hall effect is unchanged with pressure. The associated parameters which characterize the spin-split band structure are strongly dependent on pressure, reflecting the pressure-induced band deformation. We find the SdH oscillations and transport response are consistent with the theoretically proposed pressure-induced band deformation leading to a topological phase transition. Our analysis suggests the critical pressure for the quantum phase transition near Pc=3.5 GPa.

  17. Long-term spatial and temporal variation of CO2 partial pressure in the Yellow River, China

    NASA Astrophysics Data System (ADS)

    Ran, L.; Lu, X. X.; Richey, J. E.; Sun, H.; Han, J.; Yu, R.; Liao, S.; Yi, Q.

    2015-02-01

    Carbon transport in river systems is an important component of the global carbon cycle. Most rivers of the world act as atmospheric CO2 sources due to high riverine CO2 partial pressure (pCO2). By determining the pCO2 from alkalinity and pH, we investigated its spatial and temporal variation in the Yellow River watershed using historical water chemistry records (1950s-1984) and recent sampling along the mainstem (2011-2012). Except the headwater region where the pCO2 was lower than the atmospheric equilibrium (i.e. 380 μatm), river waters in the remaining watershed were supersaturated with CO2. The average pCO2 for the watershed was estimated at 2810 ± 1985 μatm, which is 7-fold the atmospheric equilibrium. As a result of severe soil erosion and dry climate, waters from the Loess Plateau in the middle reaches had higher pCO2 than that from the upper and lower reaches. From a seasonal perspective, the pCO2 varied from about 200 μatm to > 30 000 μatm with higher pCO2 usually occurring in the dry season and lower pCO2 in the wet season (at 73% of the sampling sites), suggesting the dilution effect of water. While the pCO2 responded exponentially to total suspended solids (TSS) export when the TSS concentration was less than 100 kg m-3, it decreased slightly and remained stable if the TSS concentration exceeded 100 kg m-3. This stable pCO2 is largely due to gully erosion that mobilizes subsoils characterized by low organic carbon for decomposition. In addition, human activities have changed the pCO2 dynamics. Particularly, flow regulation by dams can diversely affect the temporal changes of pCO2, depending on the physiochemical properties of the regulated waters and adopted operation scheme. Given the high pCO2 in the Yellow River waters, large potential for CO2 evasion is expected and warrants further investigation.

  18. Variation of pressure limits of flame propagation with tube diameter for various isooctane-oxygen-nitrogen mixtures

    NASA Technical Reports Server (NTRS)

    Spakowski, Adolph, A; Belles, Frank E

    1952-01-01

    An investigation was made of the change in the pressure limits of flame propagation with tube diameter for various isooctane-oxygen-nitrogen mixtures. Pressure limits were measured in cylindrical glass tubes of four different inside diameters at six different oxygen-nitrogen ratios. Under the experimental conditions, flame propagation was found to be impossible in isooctane-oxygen mixtures with oxygen concentrations less than 11 to 12 percent. Critical tube diameters for flame propagation were calculated and the effect of pressure was determined and compared with the effect of pressure on quenching distance. Critical diameters were related to flame speeds for various isooctane-oxygen-nitrogen mixtures.

  19. Numerical modelling of pore pressure variations due to time varying loads using a hybrid technique: the case of the Itoiz reservoir (Northern Spain)

    NASA Astrophysics Data System (ADS)

    Luzón, Francisco; García-Jerez, Antonio; Santoyo, Miguel A.; Sánchez-Sesma, Francisco J.

    2010-01-01

    In this work, we present a hybrid technique to estimate the pore pressure variations at the neighbourhood of dams due to time varying water loads in their reservoirs. When considering flow boundary conditions, the solution of the equations of the problem can be obtained as the superposition of (1) the part computed from a homogeneous diffusion equation with the Dirichlet boundary condition (this is due to the pore pressure diffusion) and (2) the solution of an initial value problem in an inhomogeneous diffusion equation in which the inhomogeneous term is related with the stress variations due to the water loads (the solution due to the compression in the medium). Here, two different techniques are joined to calculate each one of these partial solutions: the pore pressure diffusion term is obtained by using the Green's function of the problem, whereas the second contribution due to stress time changes is computed with a finite difference method. This hybrid technique has been used to compute the pore pressure variations produced by the initial impounding of the Itoiz reservoir, northern Spain. The possible relation between the reservoir and a close seismic series occurred on 2004 September, 8 months after the beginning of its impounding, is investigated. We pay special attention to the pore pressure changes at the hypocentre location of the main shock (with magnitude Mw = 4.5), and also evaluate the change of the Coulomb Failure Stress (ΔCFS) produced by the water loads in the reservoir over the fault responsible of this main shock, obtaining a maximum change of 0.5 kPa in the best of the cases. Accordingly, it seems that the role of the impounding of the reservoir to the main shock was marginal, and that the main load on the origin of the triggered seismicity could well be related to the regional state of stresses of the Pyrenees range and adjacent zones.

  20. [Effects of surgical treatment on circadian variations of arterial pressure in patients with primary aldosteronism and renovascular hypertension].

    PubMed

    Kosmacheva, E D; Minkin, S E; Chikhladze, N M; Arabidze, G G; At'kov, O Iu

    1990-05-01

    Noninvasive recording of blood pressure (BP) with a portable Del Mar Avionics monitor (USA) revealed its abnormal circadian rhythm in patients with renovascular hypertension or arterial hypertension caused by adrenal aldosteroma. Surgical treatment was shown to result in a significant decrease in blood pressures and normalization of its circadian rhythm in the early postoperative period. PMID:2391803

  1. The influence of pressure-dependent variation of the elastic constants on tunnelling systems in amorphous solids

    NASA Astrophysics Data System (ADS)

    Eggert, Th.; Geilenkeuser, R.; Jäckel, M.

    2000-07-01

    We have measured the dielectric response ε( ω) and the thermal conductivity κ of polystyrene (PS) and of polycarbonate (PC) under high hydrostatic pressure (0.1 MPapressure influence on the minimum temperature of Δ ε‧/ ε‧ and on κ. With the pressure dependence of the density and sound velocity of PC and PS the influence of pressure on the tunnelling constant Ci can be determined. These results show that the product P¯γ l,t2 of the standard tunnelling model (STM) scales with the pressure-dependent elastic constants c11 and c44.

  2. Variations of absolute gravity accompanying earthquake-induced changes in subsurface pore water pressure at the Mizunami Underground Research Institute construction site, central Japan

    NASA Astrophysics Data System (ADS)

    Tanaka, T.; Salden, W.; Martin, A. J.; Saegusa, H.; Asai, Y.; Fujita, Y.; Aoki, H.

    2006-03-01

    The Tono Research Institute of Earthquake Science has been measuring gravity using an FG5 absolute gravimeter located at the Mizunami Geoscience Academy (MGA) in central Japan since January 2004. Measured gravity decreased immediately following the 2004 earthquake off the Kii peninsula (MJMA 7.4) by about 6 μGal. Here, we investigate the empirical relationship between pore water pressure change in a borehole near the MGA and gravity change measured at the MGA. We reveal that (1) gravity change correlates inversely with pore water pressure change at 81 m below the surface at a particular borehole and (2) several different sets of conversion coefficients from pressure head to gravity can be used to explain 60-70% of gravity variations with less than 2 μGal uncertainty. These newly identified relationships may suggest that an absolute gravimeter alone could be used to observe the change of groundwater quantity.

  3. Pressure difference-flow rate variation in a femoral artery branch casting of man for steady flow

    NASA Technical Reports Server (NTRS)

    Cho, Y. I.; Back, L. H.; Crawford, D. W.

    1983-01-01

    In-vitro, steady flow in a casting of the profunda femoris branch of the femoral artery of man was studied by measuring pressure differences in the main lumen and also in the branch over a large Reynolds number range from 200 to 1600. Effects of viscous and inviscid flows in this femoral artery branch were demonstrated quantitatively. The critical ratio of the flow rate in the branch to the upstream main lumen in this casting was found to be 0.4, above which the inviscid flow analysis indicated a pressure rise and below which it yielded a pressure drop in the main lumen across the branch junction. Pressure rises were experimentally found to occur both in the main lumen and in the branch for certain ranges of the aforementioned ratio.

  4. Coupling changes in densities and porosity to fluid pressure variations in reactive porous fluid flow: Local thermodynamic equilibrium

    NASA Astrophysics Data System (ADS)

    Malvoisin, Benjamin; Podladchikov, Yury Yu.; Vrijmoed, Johannes C.

    2015-12-01

    Mineralogical reactions which generate or consume fluids play a key role during fluid flow in porous media. Such reactions are linked to changes in density, porosity, permeability, and fluid pressure which influence fluid flow and rock deformation. To understand such a coupled system, equations were derived from mass conservation and local thermodynamic equilibrium. The presented mass conservative modeling approach describes the relationships among evolving fluid pressure, porosity, fluid and solid density, and devolatilization reactions in multicomponent systems with solid solutions. This first step serves as a framework for future models including aqueous speciation and transport. The complexity of univariant and multivariant reactions is treated by calculating lookup tables from thermodynamic equilibrium calculations. Simplified cases were also investigated to understand previously studied formulations. For nondeforming systems or systems divided into phases of constant density, the equations can be reduced to porosity wave equations with addition of a reactive term taking the volume change of reaction into account. For closed systems, an expression for the volume change of reaction and the associated pressure increase can be obtained. The key equations were solved numerically for the case of devolatilization of three different rock types that may enter a subduction zone. Reactions with positive Clapeyron slope lead to an increase in porosity and permeability with decreasing fluid pressure resulting in sharp fluid pressure gradients around a negative pressure anomaly. The opposite trend is obtained for reactions having a negative Clapeyron slope during which sharp fluid pressure gradients were only generated around a positive pressure anomaly. Coupling of reaction with elastic deformation induces a more efficient fluid flow for reactions with negative Clapeyron slope than for reactions with positive Clapeyron slope.

  5. Interday variation and effect of transportation on indirect blood pressure measurements, plasma endothelin-1 and serum cortisol in Standardbred and Icelandic horses

    PubMed Central

    2012-01-01

    Background Systemic hypertension is a prominent feature in humans with metabolic syndrome (MS) and this is partly caused by an enhanced endothelin-1 (ET-1) mediated vasoconstriction. There are indications that systemic hypertension might be a feature in equine metabolic syndrome (EMS) but if ET-1 is involved in the development of hypertension in horses is not known. Increased levels of cortisol have also been found in humans with MS but there are no reports of this in horses. Before blood pressure, plasma ET-1 and serum cortisol can be evaluated in horses with EMS, it is necessary to investigate the interday variation of these parameters on clinically healthy horses. The aims of the present study were therefore to evaluate the interday variation and influence of transportation on systemic blood pressure, plasma ET-1 and serum cortisol in healthy Standardbred and Icelandic horses, and to detect potential breed differences. Methods Nine horses of each breed were included in the study. Blood pressure was measured and blood samples were collected between 6 and 9 am on two separate days. Eight of the horses (four of each breed) were transported to a new stable were they stayed overnight. The next morning, the sampling procedure was repeated. Results The interday variation was higher for plasma ET-1 (37%) than for indirect pressure measurements (8-21%) and serum cortisol (18%). There were no differences in systemic blood pressure between the two breeds. The Icelandic horses had significantly lower serum cortisol and significantly higher plasma ET-1 concentrations compared to the Standardbred horses. Plasma ET-1 was significantly elevated after transportation, but systemic blood pressure and serum cortisol did not differ from the values obtained in the home environment. Conclusions Indirect blood pressure, plasma ET-1 and serum cortisol are of interest as markers for cardiovascular dysfunction in horses with EMS. The elevated plasma ET-1 concentrations recorded after

  6. Abacus giving the variation of the mean pressure of an aviation engine as a function of its speed of rotation

    NASA Technical Reports Server (NTRS)

    Margoulis, W

    1921-01-01

    Comparing the results of the calculations for computing the mean pressure of an aviation engine for any number of revolutions, with those of experiment, the writer, by numerous examples, shows the perfect agreement between them. This report will show that, by means of a special abacus, an engineer can instantly plot the characteristics of an engine.

  7. Association of genetic variation with systolic and diastolic blood pressure among African Americans: the Candidate Gene Association Resource study

    PubMed Central

    Fox, Ervin R.; Young, J. Hunter; Li, Yali; Dreisbach, Albert W.; Keating, Brendan J.; Musani, Solomon K.; Liu, Kiang; Morrison, Alanna C.; Ganesh, Santhi; Kutlar, Abdullah; Ramachandran, Vasan S.; Polak, Josef F.; Fabsitz, Richard R.; Dries, Daniel L.; Farlow, Deborah N.; Redline, Susan; Adeyemo, Adebowale; Hirschorn, Joel N.; Sun, Yan V.; Wyatt, Sharon B.; Penman, Alan D.; Palmas, Walter; Rotter, Jerome I.; Townsend, Raymond R.; Doumatey, Ayo P.; Tayo, Bamidele O.; Mosley, Thomas H.; Lyon, Helen N.; Kang, Sun J.; Rotimi, Charles N.; Cooper, Richard S.; Franceschini, Nora; Curb, J. David; Martin, Lisa W.; Eaton, Charles B.; Kardia, Sharon L.R.; Taylor, Herman A.; Caulfield, Mark J.; Ehret, Georg B.; Johnson, Toby; Chakravarti, Aravinda; Zhu, Xiaofeng; Levy, Daniel; Munroe, Patricia B.; Rice, Kenneth M.; Bochud, Murielle; Johnson, Andrew D.; Chasman, Daniel I.; Smith, Albert V.; Tobin, Martin D.; Verwoert, Germaine C.; Hwang, Shih-Jen; Pihur, Vasyl; Vollenweider, Peter; O'Reilly, Paul F.; Amin, Najaf; Bragg-Gresham, Jennifer L.; Teumer, Alexander; Glazer, Nicole L.; Launer, Lenore; Zhao, Jing Hua; Aulchenko, Yurii; Heath, Simon; Sõber, Siim; Parsa, Afshin; Luan, Jian'an; Arora, Pankaj; Dehghan, Abbas; Zhang, Feng; Lucas, Gavin; Hicks, Andrew A.; Jackson, Anne U.; Peden, John F.; Tanaka, Toshiko; Wild, Sarah H.; Rudan, Igor; Igl, Wilmar; Milaneschi, Yuri; Parker, Alex N.; Fava, Cristiano; Chambers, John C.; Kumari, Meena; JinGo, Min; van der Harst, Pim; Kao, Wen Hong Linda; Sjögren, Marketa; Vinay, D.G.; Alexander, Myriam; Tabara, Yasuharu; Shaw-Hawkins, Sue; Whincup, Peter H.; Liu, Yongmei; Shi, Gang; Kuusisto, Johanna; Seielstad, Mark; Sim, Xueling; Nguyen, Khanh-Dung Hoang; Lehtimäki, Terho; Matullo, Giuseppe; Wu, Ying; Gaunt, Tom R.; Charlotte Onland-Moret, N.; Cooper, Matthew N.; Platou, Carl G.P.; Org, Elin; Hardy, Rebecca; Dahgam, Santosh; Palmen, Jutta; Vitart, Veronique; Braund, Peter S.; Kuznetsova, Tatiana; Uiterwaal, Cuno S.P.M.; Campbell, Harry; Ludwig, Barbara; Tomaszewski, Maciej; Tzoulaki, Ioanna; Palmer, Nicholette D.; Aspelund, Thor; Garcia, Melissa; Chang, Yen-Pei C.; O'Connell, Jeffrey R.; Steinle, Nanette I.; Grobbee, Diederick E.; Arking, Dan E.; Hernandez, Dena; Najjar, Samer; McArdle, Wendy L.; Hadley, David; Brown, Morris J.; Connell, John M.; Hingorani, Aroon D.; Day, Ian N.M.; Lawlor, Debbie A.; Beilby, John P.; Lawrence, Robert W.; Clarke, Robert; Collins, Rory; Hopewell, Jemma C.; Ongen, Halit; Bis, Joshua C.; Kähönen, Mika; Viikari, Jorma; Adair, Linda S.; Lee, Nanette R.; Chen, Ming-Huei; Olden, Matthias; Pattaro, Cristian; Hoffman Bolton, Judith A.; Köttgen, Anna; Bergmann, Sven; Mooser, Vincent; Chaturvedi, Nish; Frayling, Timothy M.; Islam, Muhammad; Jafar, Tazeen H.; Erdmann, Jeanette; Kulkarni, Smita R.; Bornstein, Stefan R.; Grässler, Jürgen; Groop, Leif; Voight, Benjamin F.; Kettunen, Johannes; Howard, Philip; Taylor, Andrew; Guarrera, Simonetta; Ricceri, Fulvio; Emilsson, Valur; Plump, Andrew; Barroso, Inês; Khaw, Kay-Tee; Weder, Alan B.; Hunt, Steven C.; Bergman, Richard N.; Collins, Francis S.; Bonnycastle, Lori L.; Scott, Laura J.; Stringham, Heather M.; Peltonen, Leena; Perola, Markus; Vartiainen, Erkki; Brand, Stefan-Martin; Staessen, Jan A.; Wang, Thomas J.; Burton, Paul R.; SolerArtigas, Maria; Dong, Yanbin; Snieder, Harold; Wang, Xiaoling; Zhu, Haidong; Lohman, Kurt K.; Rudock, Megan E.; Heckbert, Susan R.; Smith, Nicholas L.; Wiggins, Kerri L.; Shriner, Daniel; Veldre, Gudrun; Viigimaa, Margus; Kinra, Sanjay; Prabhakaran, Dorairajan; Tripathy, Vikal; Langefeld, Carl D.; Rosengren, Annika; Thelle, Dag S.; MariaCorsi, Anna; Singleton, Andrew; Forrester, Terrence; Hilton, Gina; McKenzie, Colin A.; Salako, Tunde; Iwai, Naoharu; Kita, Yoshikuni; Ogihara, Toshio; Ohkubo, Takayoshi; Okamura, Tomonori; Ueshima, Hirotsugu; Umemura, Satoshi; Eyheramendy, Susana; Meitinger, Thomas; Wichmann, H.-Erich; Cho, Yoon Shin; Kim, Hyung-Lae; Lee, Jong-Young; Scott, James; Sehmi, Joban S.; Zhang, Weihua; Hedblad, Bo; Nilsson, Peter; Smith, George Davey; Wong, Andrew; Narisu, Narisu; Stančáková, Alena; Raffel, Leslie J.; Yao, Jie; Kathiresan, Sekar; O'Donnell, Chris; Schwartz, Steven M.; Arfan Ikram, M.; Longstreth, Will T.; Seshadri, Sudha; Shrine, Nick R.G.; Wain, Louise V.; Morken, Mario A.; Swift, Amy J.; Laitinen, Jaana; Prokopenko, Inga; Zitting, Paavo; Cooper, Jackie A.; Humphries, Steve E.; Danesh, John; Rasheed, Asif; Goel, Anuj; Hamsten, Anders; Watkins, Hugh; Bakker, Stephan J.L.; van Gilst, Wiek H.; Janipalli, Charles S.; Radha Mani, K.; Yajnik, Chittaranjan S.; Hofman, Albert; Mattace-Raso, Francesco U.S.; Oostra, Ben A.; Demirkan, Ayse; Isaacs, Aaron; Rivadeneira, Fernando; Lakatta, Edward G.; Orru, Marco; Scuteri, Angelo; Ala-Korpela, Mika; Kangas, Antti J.; Lyytikäinen, Leo-Pekka; Soininen, Pasi; Tukiainen, Taru; Würz, Peter; Twee-Hee Ong, Rick; Dörr, Marcus; Kroemer, Heyo K.; Völker, Uwe; Völzke, Henry; Galan, Pilar; Hercberg, Serge; Lathrop, Mark; Zelenika, Diana; Deloukas, Panos; Mangino, Massimo; Spector, Tim D.; Zhai, Guangju; Meschia, James F.; Nalls, Michael A.; Sharma, Pankaj; Terzic, Janos; Kranthi Kumar, M.J.; Denniff, Matthew; Zukowska-Szczechowska, Ewa; Wagenknecht, Lynne E.; Fowkes, Gerald R.; Charchar, Fadi J.; Schwarz, Peter E.H.; Hayward, Caroline; Guo, Xiuqing; Bots, Michiel L.; Brand, Eva; Samani, Nilesh J.; Polasek, Ozren; Talmud, Philippa J.; Nyberg, Fredrik; Kuh, Diana; Laan, Maris; Hveem, Kristian; Palmer, Lyle J.; van der Schouw, Yvonne T.; Casas, Juan P.; Mohlke, Karen L.; Vineis, Paolo; Raitakari, Olli; Wong, Tien Y.; Shyong Tai, E.; Laakso, Markku; Rao, Dabeeru C.; Harris, Tamara B.; Morris, Richard W.; Dominiczak, Anna F.; Kivimaki, Mika; Marmot, Michael G.; Miki, Tetsuro; Saleheen, Danish; Chandak, Giriraj R.; Coresh, Josef; Navis, Gerjan; Salomaa, Veikko; Han, Bok-Ghee; Kooner, Jaspal S.; Melander, Olle; Ridker, Paul M.; Bandinelli, Stefania; Gyllensten, Ulf B.; Wright, Alan F.; Wilson, James F.; Ferrucci, Luigi; Farrall, Martin; Tuomilehto, Jaakko; Pramstaller, Peter P.; Elosua, Roberto; Soranzo, Nicole; Sijbrands, Eric J.G.; Altshuler, David; Loos, Ruth J.F.; Shuldiner, Alan R.; Gieger, Christian; Meneton, Pierre; Uitterlinden, Andre G.; Wareham, Nicholas J.; Gudnason, Vilmundur; Rettig, Rainer; Uda, Manuela; Strachan, David P.; Witteman, Jacqueline C.M.; Hartikainen, Anna-Liisa; Beckmann, Jacques S.; Boerwinkle, Eric; Boehnke, Michael; Larson, Martin G.; Järvelin, Marjo-Riitta; Psaty, Bruce M.; Abecasis, Gonçalo R.; Elliott, Paul; van Duijn , Cornelia M.; Newton-Cheh, Christopher

    2011-01-01

    The prevalence of hypertension in African Americans (AAs) is higher than in other US groups; yet, few have performed genome-wide association studies (GWASs) in AA. Among people of European descent, GWASs have identified genetic variants at 13 loci that are associated with blood pressure. It is unknown if these variants confer susceptibility in people of African ancestry. Here, we examined genome-wide and candidate gene associations with systolic blood pressure (SBP) and diastolic blood pressure (DBP) using the Candidate Gene Association Resource (CARe) consortium consisting of 8591 AAs. Genotypes included genome-wide single-nucleotide polymorphism (SNP) data utilizing the Affymetrix 6.0 array with imputation to 2.5 million HapMap SNPs and candidate gene SNP data utilizing a 50K cardiovascular gene-centric array (ITMAT-Broad-CARe [IBC] array). For Affymetrix data, the strongest signal for DBP was rs10474346 (P= 3.6 × 10−8) located near GPR98 and ARRDC3. For SBP, the strongest signal was rs2258119 in C21orf91 (P= 4.7 × 10−8). The top IBC association for SBP was rs2012318 (P= 6.4 × 10−6) near SLC25A42 and for DBP was rs2523586 (P= 1.3 × 10−6) near HLA-B. None of the top variants replicated in additional AA (n = 11 882) or European-American (n = 69 899) cohorts. We replicated previously reported European-American blood pressure SNPs in our AA samples (SH2B3, P= 0.009; TBX3-TBX5, P= 0.03; and CSK-ULK3, P= 0.0004). These genetic loci represent the best evidence of genetic influences on SBP and DBP in AAs to date. More broadly, this work supports that notion that blood pressure among AAs is a trait with genetic underpinnings but also with significant complexity. PMID:21378095

  8. Association of genetic variation with systolic and diastolic blood pressure among African Americans: the Candidate Gene Association Resource study.

    PubMed

    Fox, Ervin R; Young, J Hunter; Li, Yali; Dreisbach, Albert W; Keating, Brendan J; Musani, Solomon K; Liu, Kiang; Morrison, Alanna C; Ganesh, Santhi; Kutlar, Abdullah; Ramachandran, Vasan S; Polak, Josef F; Fabsitz, Richard R; Dries, Daniel L; Farlow, Deborah N; Redline, Susan; Adeyemo, Adebowale; Hirschorn, Joel N; Sun, Yan V; Wyatt, Sharon B; Penman, Alan D; Palmas, Walter; Rotter, Jerome I; Townsend, Raymond R; Doumatey, Ayo P; Tayo, Bamidele O; Mosley, Thomas H; Lyon, Helen N; Kang, Sun J; Rotimi, Charles N; Cooper, Richard S; Franceschini, Nora; Curb, J David; Martin, Lisa W; Eaton, Charles B; Kardia, Sharon L R; Taylor, Herman A; Caulfield, Mark J; Ehret, Georg B; Johnson, Toby; Chakravarti, Aravinda; Zhu, Xiaofeng; Levy, Daniel

    2011-06-01

    The prevalence of hypertension in African Americans (AAs) is higher than in other US groups; yet, few have performed genome-wide association studies (GWASs) in AA. Among people of European descent, GWASs have identified genetic variants at 13 loci that are associated with blood pressure. It is unknown if these variants confer susceptibility in people of African ancestry. Here, we examined genome-wide and candidate gene associations with systolic blood pressure (SBP) and diastolic blood pressure (DBP) using the Candidate Gene Association Resource (CARe) consortium consisting of 8591 AAs. Genotypes included genome-wide single-nucleotide polymorphism (SNP) data utilizing the Affymetrix 6.0 array with imputation to 2.5 million HapMap SNPs and candidate gene SNP data utilizing a 50K cardiovascular gene-centric array (ITMAT-Broad-CARe [IBC] array). For Affymetrix data, the strongest signal for DBP was rs10474346 (P= 3.6 × 10(-8)) located near GPR98 and ARRDC3. For SBP, the strongest signal was rs2258119 in C21orf91 (P= 4.7 × 10(-8)). The top IBC association for SBP was rs2012318 (P= 6.4 × 10(-6)) near SLC25A42 and for DBP was rs2523586 (P= 1.3 × 10(-6)) near HLA-B. None of the top variants replicated in additional AA (n = 11 882) or European-American (n = 69 899) cohorts. We replicated previously reported European-American blood pressure SNPs in our AA samples (SH2B3, P= 0.009; TBX3-TBX5, P= 0.03; and CSK-ULK3, P= 0.0004). These genetic loci represent the best evidence of genetic influences on SBP and DBP in AAs to date. More broadly, this work supports that notion that blood pressure among AAs is a trait with genetic underpinnings but also with significant complexity. PMID:21378095

  9. Note: implementation of a cold spot setup for controlled variation of vapor pressures and its application to an InBr containing discharge lamp.

    PubMed

    Briefi, S

    2013-02-01

    In order to allow for a systematic investigation of the plasma properties of discharges containing indium halides, which are proposed as an efficient alternative for mercury based low pressure discharge lamps, a controlled variation of the indium halide density is mandatory. This can be achieved by applying a newly designed setup in which a well-defined cold spot location is implemented and the cold spot temperature can be adjusted between 50 and 350 °C without influencing the gas temperature. The performance of the setup has been proved by comparing the calculated evaporated InBr density (using the vapor pressure curve) with the one measured via white light absorption spectroscopy. PMID:23464268

  10. Seasonal variation in blood pressure and its relationship with outdoor temperature in 10 diverse regions of China: the China Kadoorie Biobank

    PubMed Central

    LEWINGTON, Sarah; LI, LiMing; SHERLIKER, Paul; GUO, Yu; MILLWOOD, Iona; BIAN, Zheng; WHITLOCK, Gary; YANG, Ling; COLLINS, Rory; CHEN, Junshi; WU, Xianping; WANG, Shaojie; HU, Yihe; JIANG, Li; YANG, Liqiu; LACEY, Ben; PETO, Richard; CHEN, Zhengming

    2015-01-01

    Objectives Mean blood pressure varies moderately with outdoor air temperature in many Western populations. Substantial uncertainty exists, however, about the strength of the relationship in other populations, and the relevance to it of age, adiposity, medical treatment, climate and housing conditions. Methods To investigate the relationship of blood pressure with season and outdoor temperature, we analysed cross-sectional data from the China Kadoorie Biobank study of 506 673 adults aged 30-79 recruited from ten diverse urban and rural regions in China. Analyses related mean blood pressure – overall and in various subgroups – to mean local outdoor temperature. Results The mean difference in systolic blood pressure (SBP) between summer (June-August) and winter (December-February) was 10 mmHg overall, and was more extreme, on average, in rural than in urban areas (12 vs. 8 mmHg; p for interaction<0.0001). Above 5°C, SBP was strongly inversely associated with outdoor temperature in all ten areas studied, with 5.7 (SE 0.04) mmHg higher SBP per 10°C lower outdoor temperature. The association was stronger in older people and in those with lower body mass index. At lower temperatures there was no evidence of an association among participants who reported having home central heating. Conclusions Blood pressure was strongly inversely associated with outdoor temperature in Chinese adults across a range of climatic conditions, although access to home central heating appeared to remove much of the association during the winter months. Seasonal variation in blood pressure should be considered in the clinical management of hypertension. PMID:22688260

  11. AFM Nanolithography of Lanthanum Barium Manganese Oxide (LaBaMnO3)Thin Films: The Effect of Oxygen Pressure Variations During Film Growth

    NASA Astrophysics Data System (ADS)

    Stumpf, Christoper; Schaefer, David; Kolagani, Rajeswari; Yong, Grace; Warecki, Zoey

    2014-03-01

    In AFM nanolithography, a bias voltage applied between the tip of an atomic force microscope (AFM) and a sample is used to produce nanoscale modifications of material surfaces. AFM nanolithography has been studied extensively on a variety of materials, but limited studies have been performed on perovskite manganites such as Lanthanum Barium Manganese Oxide (LBMO). Studying such materials is important because of their potential applications for room-temperature nanoscale spintronic devices. Previous research on LBMO by our group has focused on how parameters such as applied tip voltage, temperature, and humidity affect the creation of nanopatterns. This paper reports on the influence of growth pressure of the LBMO films grown by pulsed laser deposition. Films grown on (100) SrTiO3 were studied for growth pressures ranging between 100 mTorr to 400 mTorr. Our studies indicate that the type of nanopatterns induced by AFM and the relaxation dynamics of these patterns are sensitive to the film growth pressure. The growth pressure is mainly known to affect the oxygen concentration and the surface roughness, but possible variations in cationic stoichiometry could also contribute to these results. RK and GY acknowledge support from the National Science Foundation Grant ECCS 1128586.

  12. The response of polymethyl methacrylate (PMMA) subjected to large strains, high strain rates, high pressures, a range in temperatures, and variations in the intermediate principal stress

    NASA Astrophysics Data System (ADS)

    Holmquist, T. J.; Bradley, J.; Dwivedi, A.; Casem, D.

    2016-05-01

    This article presents the response of polymethyl methacrylate (PMMA) subjected to large strains, high strain rates, high pressures, a range in temperatures, and variations in the intermediate principal stress. Laboratory data from the literature, and new test data provided here, are used in the evaluation. The new data include uniaxial stress compression tests (at various strain rates and temperatures) and uniaxial stress tension tests (at low strain rates and ambient temperatures). The compression tests include experiments at ˙ɛ = 13,000 s-1, significantly extending the range of known strain rate data. The observed behavior of PMMA includes the following: it is brittle in compression at high rates, and brittle in tension at all rates; strength is dependent on the pressure, strain, strain rate, temperature, and the intermediate principal stress; the shear modulus increases as the pressure increases; and it is highly compressible. Also presented are novel, high velocity impact tests (using high-speed imaging) that provide insight into the initiation and evolution of damage. Lastly, computational constitutive models for pressure, strength, and failure are presented that provide responses that are in good agreement with the laboratory data. The models are used to compute several ballistic impact events for which experimental data are available.

  13. Antigenic variation in Treponema pallidum: TprK sequence diversity accumulates in response to immune pressure during experimental syphilis1

    PubMed Central

    Giacani, Lorenzo; Molini, Barbara J.; Kim, Eric Y.; Godornes, B. Charmie; Leader, B. Troy; Tantalo, Lauren C.; Centurion-Lara, Arturo; Lukehart, Sheila A.

    2010-01-01

    Pathogens that cause chronic infections often employ antigenic variation to evade the immune response and persist in the host. In Treponema pallidum (T. pallidum), the causative agent of syphilis, the TprK antigen undergoes variation of seven variable regions (V1-V7) by nonreciprocal recombination of silent donor cassettes with the tprK expression site. These V regions are the targets of the host humoral immune response during experimental infection. The present study addresses the causal role of the acquired immune response in the selection of TprK variants in two ways: 1) by investigating TprK variants arising in immunocompetent vs immunosuppressed hosts, and 2) by investigating the effect of prior specific immunization on selection of TprK variants during infection. V region diversity, particularly in V6, accumulates more rapidly in immunocompetent rabbits than in pharmacologically immunosuppressed rabbits (treated with weekly injections of methylprednisolone acetate). In a complementary experiment, rabbits pre-immunized with V6 region synthetic peptides had more rapid accumulation of V6 variant treponemes than control rabbits. These studies demonstrate that the host immune response selects against specific TprK epitopes expressed on T. pallidum, resulting in immune selection of new TprK variants during infection, confirming a role for antigenic variation in syphilis. PMID:20190145

  14. Temporal variation of the arterial pressure in healthy young people and its relation to geomagnetic activity in Mexico

    NASA Astrophysics Data System (ADS)

    Azcárate, T.; Mendoza, B.; Sánchez de la Peña, S.; Martínez, J. L.

    2012-11-01

    We present a study of the temporal behavior of the systolic (SBP) and diastolic (DBP) blood pressure for a sample of 51 normotensive, healthy volunteers, 18 men and 33 women with an average age of 19 years old in Mexico City, Mexico, during April and May, 2008. We divided the data by sex along the circadian rhythm. Three geomagnetic storms occurred during the studied time-span. The strongest one, a moderate storm, is attributed to a coronal hole border that reached the Earth. The ANOVA test applied to the strongest storm showed that even though we are dealing with a moderate geomagnetic storm, there are statistically significant responses of the blood pressure. The superposed epoch analysis during a three-day window around the strongest storm shows that on average the largest changes occurred for the SBP. Moreover, the SBP largest increases occurred two days before and one day after this storm, and women are the most sensitive group as they present larger SBP and DBP average changes than men. Finally, given the small size of the sample, we cannot generalize our results.

  15. Negating the Yearly Eccentricity Magnitude Variation of Super-synchronous Disposal Orbits due to Solar Radiation Pressure

    NASA Astrophysics Data System (ADS)

    Jones, S. L.

    Solar radiation pressure alters satellites' eccentricity by accelerating and decelerating them during each orbit. The accumulated perturbation cancels yearly for geostationary satellites, but meanwhile the perigee radius changes. Disposed satellites must be reorbited higher to compensate, using more fuel. The examined disposal orbit points toward the Sun and uses the satellite's natural eccentricity. This causes the eccentricity vector to only change direction, keeping the perigee radius constant. This thesis verifies this behavior over one year with an analytical derivation and MATLAB simulation, gaining useful insights into its cause. The traditional and proposed disposal orbits are then modeled using NASA's GMAT for more realistic simulations. The proposed orbit's sensitivity to satellite and initialization errors is also examined. Relationships are developed to show these errors' effect on the perigee radius. In conclusion, while this orbit can be used in the short term, margins are necessary to guarantee protection of the geostationary belt.

  16. Modification of a variational objective analysis model for new equations for pressure gradient and vertical velocity in the lower troposphere and for spatial resolution and accuracy of satellite data

    NASA Technical Reports Server (NTRS)

    Achtemeier, G. L.

    1986-01-01

    Since late 1982 NASA has supported research to develop a numerical variational model for the diagnostic assimilation of conventional and space-based meteorological data. In order to analyze the model components, four variational models are defined dividing the problem naturally according to increasing complexity. The first of these variational models (MODEL I), the subject of this report, contains the two nonlinear horizontal momentum equations, the integrated continuity equation, and the hydrostatic equation. This report summarizes the results of research (1) to improve the way the large nonmeteorological parts of the pressure gradient force are partitioned between the two terms of the pressure gradient force terms of the horizontal momentum equations, (2) to generalize the integrated continuity equation to account for variable pressure thickness over elevated terrain, and (3) to introduce horizontal variation in the precision modulus weights for the observations.

  17. A molecular dynamics study of ambient and high pressure phases of silica: structure and enthalpy variation with molar volume.

    PubMed

    Rajappa, Chitra; Sringeri, S Bhuvaneshwari; Subramanian, Yashonath; Gopalakrishnan, J

    2014-06-28

    Extensive molecular dynamics studies of 13 different silica polymorphs are reported in the isothermal-isobaric ensemble with the Parrinello-Rahman variable shape simulation cell. The van Beest-Kramer-van Santen (BKS) potential is shown to predict lattice parameters for most phases within 2%-3% accuracy, as well as the relative stabilities of different polymorphs in agreement with experiment. Enthalpies of high-density polymorphs - CaCl2-type, α-PbO2-type, and pyrite-type - for which no experimental data are available as yet, are predicted here. Further, the calculated enthalpies exhibit two distinct regimes as a function of molar volume-for low and medium-density polymorphs, it is almost independent of volume, while for high-pressure phases a steep dependence is seen. A detailed analysis indicates that the increased short-range contributions to enthalpy in the high-density phases arise not only from an increased coordination number of silicon but also shorter Si-O bond lengths. Our results indicate that amorphous phases of silica exhibit better optimization of short-range interactions than crystalline phases at the same density while the magnitude of Coulombic contributions is lower in the amorphous phase. PMID:24985659

  18. Variation of spatial distribution of excited species in He/Ar/O2 admixtures in an atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Taylor, Sarah; Leiweke, Robert; Ganguly, Biswa

    2012-10-01

    Variation of cathode directed streamer initiated pulsed glow current and spatial distribution of excited species outside the 4 mm capillary of a He/Ar/O2 plasma jet have been measured using a partially optically transmitting conducting cathode. For 18 mm inter-electrode gap, 15 ns rise time unipolar 12.5 kV pulsed applied voltage with 6 kHz repetition rate, the pulsed glow current peaked at 150 mA with 1% Ar added to He flow, compared to 100 mA in pure He, into ambient air at 1.6 SLM. Spatiotemporally and spectrally resolved head-on emission images from He 3^3D->2^3P, Ar 2p1->1s2, O ^5P->^5S, and N2^+ B^2σ->X^2σ transitions were acquired along the discharge propagation axis using a 5 ns gate ICCD camera. A fiber-couple PMT lens viewing normal to the propagation axis collected the same species emission, at 4 and 8 mm from the capillary tip, in order to correlate temporal emission profiles from streamer to glow transition. For each admixture, the ICCD radial emission profile for each excited species peaks on axis with a mean FWHM of ˜1.5 mm, whereas for pure He the intensity distribution of all excited species is annular. Concurrent with the increased discharge conductivity with 1% Ar admixture, the 777 nm O atom emission intensity increased in both streamer and glow phases.

  19. Diurnal Variations in Intraocular Pressure, Central Corneal Thickness, and Macular and Retinal Nerve Fiber Layer Thickness in Diabetics and Normal Individuals

    PubMed Central

    Sharifipour, Farideh; Farrahi, Fereidoun; Moghaddasi, Alireza; Idani, Aida; Yaseri, Mehdi

    2016-01-01

    Purpose: To evaluate diurnal variations in intraocular pressure (IOP), central corneal thickness (CCT), and macular and retinal nerve fiber layer (RNFL) thickness in diabetic patients and normal individuals. Methods: This study included 11 diabetic patients with macular edema and 11 healthy individuals. IOP, CCT, and macular and RNFL thickness were measured every 3 hours on a single day between 9 AM and 6 PM. Diurnal variations in IOP, CCT, total macular volume (TMV), central macular thickness (CMT), average macular thickness (AMT), and RNFL thickness were measured. Results: None of the parameters showed a significant absolute or relative change over the course of the day. However, the following non-significant changes were observed. In the control group, all parameters demonstrated the highest values at 9 AM. The lowest IOP, TMV and AMT occurred at 12 PM; lowest CCT and RNFL at 6 PM; and the lowest CMT at 3 PM. Diabetic subjects had the highest values of RNFL, CMT and TMV at 9 AM, and that for IOP, CCT and AMT at 6 PM. The lowest RNFL and CMT values occurred at 6 PM; lowest IOP at 12 PM; and the lowest CCT, TMV and AMT were observed at 3 PM. In the diabetic group, TMV, CMT, AMT and CCT were significantly higher and RNFL was significantly lower than the control group at all time points (all P- values < 0.05). Conclusion: While there were slight decreases in IOP, RNFL thickness and CMT during the day, these changes were not significant between 9 AM and 6 PM and probably do not affect the interpretation of measurements. PMID:27195084

  20. Changes in pulse pressure variation and plethysmographic variability index caused by hypotension-inducing hemorrhage followed by volume replacement in isoflurane-anesthetized dogs.

    PubMed

    Klein, Adriana V; Teixeira-Neto, Francisco J; Garofalo, Natache A; Lagos-Carvajal, Angie P; Diniz, Miriely S; Becerra-Velásquez, Diana R

    2016-03-01

    OBJECTIVE To compare changes in pulse pressure variation (PPV) and plethysmographic variability index (PVI) induced by hemorrhage followed by volume replacement (VR) in isoflurane-anesthetized dogs. ANIMALS 7 healthy adult dogs. PROCEDURE Each dog was anesthetized with isoflurane and mechanically ventilated. End-tidal isoflurane concentration was adjusted to maintain mean arterial pressure (MAP) at 60 to 70 mm Hg before hemorrhage. Controlled hemorrhage was initiated and continued until the MAP decreased to 40 to 50 mm Hg, then autologous blood removed during hemorrhage was retransfused during VR. Various physiologic variables including PPV and PVI were recorded immediately before (baseline) and after controlled hemorrhage and immediately after VR. RESULTS Mean ± SD PPV and PVI were significantly increased from baseline after hemorrhage (PPV, 20 ± 6%; PVI, 18 ± 4%). After VR, the mean PPV (7 ± 3%) returned to a value similar to baseline, whereas the mean PVI (10 ± 3%) was significantly lower than that at baseline. Cardiac index (CI) and stroke index (SI) were significantly decreased from baseline after hemorrhage (CI, 2.07 ± 0.26 L/min/m(2); SI, 20 ± 3 mL/beat/m(2)) and returned to values similar to baseline after VR (CI, 4.25 ± 0.63 L/min/m(2); SI, 36 ± 6 mL/beat/m(2)). There was a significant positive correlation (r(2) = 0.77) between PPV and PVI after hemorrhage. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that both PPV and PVI may be useful for identification of dogs that respond to VR with increases in SI and CI (ie, dogs in the preload-dependent limb of the Frank-Starling curve). PMID:26919599

  1. Between-Habitat Variation of Benthic Cover, Reef Fish Assemblage and Feeding Pressure on the Benthos at the Only Atoll in South Atlantic: Rocas Atoll, NE Brazil

    PubMed Central

    Longo, G. O.; Morais, R. A.; Martins, C. D. L.; Mendes, T. C.; Aued, A. W.; Cândido, D. V.; de Oliveira, J. C.; Nunes, L. T.; Fontoura, L.; Sissini, M. N.; Teschima, M. M.; Silva, M. B.; Ramlov, F.; Gouvea, L. P.; Ferreira, C. E. L.; Segal, B.; Horta, P. A.; Floeter, S. R.

    2015-01-01

    The Southwestern Atlantic harbors unique and relatively understudied reef systems, including the only atoll in South Atlantic: Rocas atoll. Located 230 km off the NE Brazilian coast, Rocas is formed by coralline red algae and vermetid mollusks, and is potentially one of the most “pristine” areas in Southwestern Atlantic. We provide the first comprehensive and integrative description of the fish and benthic communities inhabiting different shallow reef habitats of Rocas. We studied two contrasting tide pool habitats: open pools, which communicate with the open ocean even during low tides, thus more exposed to wave action; and closed pools, which remain isolated during low tide and are comparatively less exposed. Reef fish assemblages, benthic cover, algal turfs and fish feeding pressure on the benthos remarkably varied between open and closed pools. The planktivore Thalassoma noronhanum was the most abundant fish species in both habitats. In terms of biomass, the lemon shark Negaprion brevirostris and the omnivore Melichtys niger were dominant in open pools, while herbivorous fishes (mainly Acanthurus spp.) prevailed in closed pools. Overall benthic cover was dominated by algal turfs, composed of articulated calcareous algae in open pools and non-calcified algae in closed pools. Feeding pressure was dominated by acanthurids and was 10-fold lower in open pools than in closed pools. Besides different wave exposure conditions, such pattern could also be related to the presence of sharks in open pools, prompting herbivorous fish to feed more in closed pools. This might indirectly affect the structure of reef fish assemblages and benthic communities. The macroalgae Digenea simplex, which is uncommon in closed pools and abundant in the reef flat, was highly preferred in herbivory assays, indicating that herbivory by fishes might be shaping this distribution pattern. The variations in benthic and reef fish communities, and feeding pressure on the benthos between open

  2. Between-Habitat Variation of Benthic Cover, Reef Fish Assemblage and Feeding Pressure on the Benthos at the Only Atoll in South Atlantic: Rocas Atoll, NE Brazil.

    PubMed

    Longo, G O; Morais, R A; Martins, C D L; Mendes, T C; Aued, A W; Cândido, D V; de Oliveira, J C; Nunes, L T; Fontoura, L; Sissini, M N; Teschima, M M; Silva, M B; Ramlov, F; Gouvea, L P; Ferreira, C E L; Segal, B; Horta, P A; Floeter, S R

    2015-01-01

    The Southwestern Atlantic harbors unique and relatively understudied reef systems, including the only atoll in South Atlantic: Rocas atoll. Located 230 km off the NE Brazilian coast, Rocas is formed by coralline red algae and vermetid mollusks, and is potentially one of the most "pristine" areas in Southwestern Atlantic. We provide the first comprehensive and integrative description of the fish and benthic communities inhabiting different shallow reef habitats of Rocas. We studied two contrasting tide pool habitats: open pools, which communicate with the open ocean even during low tides, thus more exposed to wave action; and closed pools, which remain isolated during low tide and are comparatively less exposed. Reef fish assemblages, benthic cover, algal turfs and fish feeding pressure on the benthos remarkably varied between open and closed pools. The planktivore Thalassoma noronhanum was the most abundant fish species in both habitats. In terms of biomass, the lemon shark Negaprion brevirostris and the omnivore Melichtys niger were dominant in open pools, while herbivorous fishes (mainly Acanthurus spp.) prevailed in closed pools. Overall benthic cover was dominated by algal turfs, composed of articulated calcareous algae in open pools and non-calcified algae in closed pools. Feeding pressure was dominated by acanthurids and was 10-fold lower in open pools than in closed pools. Besides different wave exposure conditions, such pattern could also be related to the presence of sharks in open pools, prompting herbivorous fish to feed more in closed pools. This might indirectly affect the structure of reef fish assemblages and benthic communities. The macroalgae Digenea simplex, which is uncommon in closed pools and abundant in the reef flat, was highly preferred in herbivory assays, indicating that herbivory by fishes might be shaping this distribution pattern. The variations in benthic and reef fish communities, and feeding pressure on the benthos between open and

  3. Evaluation of physiological risk factors, oxidant-antioxidant imbalance, proteolytic and genetic variations of matrix metalloproteinase-9 in patients with pressure ulcer

    PubMed Central

    Latifa, Khlifi; Sondess, Sahli; Hajer, Graiet; Manel, Ben-Hadj-Mohamed; Souhir, Khelil; Nadia, Bouzidi; Abir, Jaballah; Salima, Ferchichi; Abdelhedi, Miled

    2016-01-01

    Pressure ulcer (PU) remains a common worldwide problem in all health care settings, it is synonymous with suffering. PU is a complex disease that is dependent on a number of interrelated factors. It involves multiple mechanisms such as physiological risk factors, chronic inflammation, oxidant–antioxidant imbalance and proteolytic attack on extracellular matrix by matrix metalloproteinases (MMP). Therefore, we propose that these wounds lead to molecular variations that can be detected by assessing biomarkers. In this study, we aimed to evaluate the major clinical elements and biological scars in Tunisian patients suffering from PU. Consistently, non-healing wound remains a challenging clinical problem. The complex challenges of the wound environment, involving nutrient deficiencies, bacterial infection, as well as the critical role played by inflammatory cells, should be considered because of their negative impact on wound healing. In addition, an imbalance between pro-oxidants and antioxidant systems seems to be more aggravated in patients with PU compared to healthy subjects. Of interest, this study provides further evidence to support a core role of the biological activity of MMP-9 in the pathogenesis of PU and indicates that the MMP9-1562 C/T (rs 3918242) functional polymorphism is associated with protection against this disease. PMID:27405842

  4. Evaluation of physiological risk factors, oxidant-antioxidant imbalance, proteolytic and genetic variations of matrix metalloproteinase-9 in patients with pressure ulcer.

    PubMed

    Latifa, Khlifi; Sondess, Sahli; Hajer, Graiet; Manel, Ben-Hadj-Mohamed; Souhir, Khelil; Nadia, Bouzidi; Abir, Jaballah; Salima, Ferchichi; Abdelhedi, Miled

    2016-01-01

    Pressure ulcer (PU) remains a common worldwide problem in all health care settings, it is synonymous with suffering. PU is a complex disease that is dependent on a number of interrelated factors. It involves multiple mechanisms such as physiological risk factors, chronic inflammation, oxidant-antioxidant imbalance and proteolytic attack on extracellular matrix by matrix metalloproteinases (MMP). Therefore, we propose that these wounds lead to molecular variations that can be detected by assessing biomarkers. In this study, we aimed to evaluate the major clinical elements and biological scars in Tunisian patients suffering from PU. Consistently, non-healing wound remains a challenging clinical problem. The complex challenges of the wound environment, involving nutrient deficiencies, bacterial infection, as well as the critical role played by inflammatory cells, should be considered because of their negative impact on wound healing. In addition, an imbalance between pro-oxidants and antioxidant systems seems to be more aggravated in patients with PU compared to healthy subjects. Of interest, this study provides further evidence to support a core role of the biological activity of MMP-9 in the pathogenesis of PU and indicates that the MMP9-1562 C/T (rs 3918242) functional polymorphism is associated with protection against this disease. PMID:27405842

  5. Statistical evaluation of the through-thickness copper variation and the K{sub Ic} and K{sub Ia} curves for reactor pressure vessels

    SciTech Connect

    Simonen, F.A.; Khaleel, M.A.

    1995-11-01

    This paper describes a statistical evaluation of the through-thickness copper variation for welds in reactor pressure vessels, and reviews the historical basis for the static and arrest fracture toughness (K{sub Ic} and K{sub Ia}) equations used in the VISA-II code. Copper variability in welds is due to fabrication procedures with copper contents being randomly distributed, variable from one location to another through the thickness of the vessel. The VISA-II procedure of sampling the copper content from a statistical distribution for every 6.35- to 12.7-mm (1/4- to 1/2-in.) layer through the thickness was found to be consistent with the statistical observations. However, the parameters of the VISA-II distribution and statistical limits required further investigation. Copper contents at few locations through the thickness were found to exceed the 0.4% upper limit of the VISA-II code. The data also suggest that the mean copper content varies systematically through the thickness. While, the assumption of normality is not clearly supported by the available data, a statistical evaluation based on all the available data results in mean and standard deviations within the VISA-II code limits.

  6. Pressure dissociation of integration host factor–DNA complexes reveals flexibility-dependent structural variation at the protein–DNA interface

    PubMed Central

    Senear, Donald F.; Tretyachenko-Ladokhina, Vira; Opel, Michael L.; Aeling, Kimberly A.; Wesley Hatfield, G.; Franklin, Laurie M.; Darlington, Reuben C.

    2007-01-01

    E. coli Integration host factor (IHF) condenses the bacterial nucleoid by wrapping DNA. Previously, we showed that DNA flexibility compensates for structural characteristics of the four consensus recognition elements associated with specific binding (Aeling et al., J. Biol. Chem. 281, 39236–39248, 2006). If elements are missing, high-affinity binding occurs only if DNA deformation energy is low. In contrast, if all elements are present, net binding energy is unaffected by deformation energy. We tested two hypotheses for this observation: in complexes containing all elements, (1) stiff DNA sequences are less bent upon binding IHF than flexible ones; or (2) DNA sequences with differing flexibility have interactions with IHF that compensate for unfavorable deformation energy. Time-resolved Förster resonance energy transfer (FRET) shows that global topologies are indistinguishable for three complexes with oligonucleotides of different flexibility. However, pressure perturbation shows that the volume change upon binding is smaller with increasing flexibility. We interpret these results in the context of Record and coworker's model for IHF binding (J. Mol. Biol. 310, 379–401, 2001). We propose that the volume changes reflect differences in hydration that arise from structural variation at IHF–DNA interfaces while the resulting energetic compensation maintains the same net binding energy. PMID:17324943

  7. Silane-initiated nucleation in chemically active plasmas: validation of density functionals, mechanisms, and pressure-dependent variational transition state calculations.

    PubMed

    Bao, Junwei Lucas; Truhlar, Donald G

    2016-04-21

    The growth of anionic silicon hydride clusters is a critically important process in nanodusty plasmas. In the current study, we focus on the formation of homologs of silylene (Sin+1H2n+2(-), n = 3, 4) and silyl (SinH2n+1(-), n = 4, 5) anions via anion-neutral reaction pathways. Species like silyl or silylene anions and their related elementary reactions, which are involved in the formation of silicon hydride clusters, were not used in developing exchange-correlation (xc) density functionals (i.e., they were not included in the training set of semiempirical density functionals); therefore, we explored the accuracy of various widely used xc density functionals based on reaction energies and barrier heights. Among the 21 density functionals we tested, M06-2X has the best performance for a hybrid functional, and MN15-L has the best performance for a local functional. Thermal rate constants of the elementary reactions involved in the reaction mechanism are calculated using M06-2X and multistructural canonical variational transition state theory with the small-curvature tunneling approximation (MS-CVT/SCT). The pressure dependence of unimolecular isomerization reactions is treated with system-specific quantum RRK theory (SS-QRRK) and the Lindemann-Hinshelwood mechanism. PMID:27009479

  8. The comparison of stroke volume variation with central venous pressure in predicting fluid responsiveness in septic patients with acute circulatory failure

    PubMed Central

    Angappan, Santhalakshmi; Parida, Satyen; Vasudevan, Arumugam; Badhe, Ashok Shankar

    2015-01-01

    Purpose: The present study was designed to investigate the efficacy of stroke volume variation (SVV) in predicting fluid responsiveness and compare it to traditional measures of volume status assessment like central venous pressure (CVP). Methods: Forty-five mechanically ventilated patients in sepsis with acute circulatory failure. Patients were not included when they had atrial fibrillation, other severe arrhythmias, permanent pacemaker, or needed mechanical cardiac support. Furthermore, excluded were patients with hypoxemia and a CVP >12. Patients received volume expansion in the form of 500 ml of 6% hydroxyethyl starch. Results: The volume expansion-induced increase in  cardiac index (CI) was >15% in 29 patients (labeled responders) and <15% in 16 patients (labeled nonresponders). Before volume expansion, SVV was higher in responders than in nonresponders. Receiver operating characteristic curves analysis showed that SVV was a more accurate indicator of fluid responsiveness than CVP. Before volume expansion, an SVV value of 13% allowed discrimination between responders and nonresponders with a sensitivity of 78% and a specificity of 89%. Volume expansion-induced changes in CI weakly and positively correlated with SVV before volume expansion. Volume expansion decreased SVV from 18.86 ± 4.35 to 7.57 ± 1.80 and volume expansion-induced changes in SVV moderately correlated with volume expansion-induced changes in CI. Conclusions: When predicting fluid responsiveness in mechanically ventilated patients in septic shock, SVV is more effective than CVP. Nevertheless, the overall correlation of baseline SVV with increases in CI remains poor. Trends in SVV, as reflected by decreases with volume replacement, seem to correlate much better with increases in CI. PMID:26180432

  9. A fluid inclusion study of fluid pressure and salinity variations in the footwall of the rector branch thrust, North Carolina, U.S.A.

    NASA Astrophysics Data System (ADS)

    O'Hara, Kieran; Haak, Amy

    1992-05-01

    Last melting and homogenization temperatures of fluid inclusions from plastically deformed bedding-parallel quartz veins in the footwall of the Rector Branch thrust, North Carolina, were studied as a function of distance from the thrust. Fluid inclusions and microstructures in mylonitic rocks within the thrust zone were also examined. Fluid inclusions in quartz veins which display evidence for intracrystalline plasticity (e.g. subgrain polygonization) occur along subgrain boundaries and have higher homogenization temperatures ( Tn) and a wider range (120-320°C) compared to less deformed samples. Maximum Th values, which approach the temperature of deformation (300 ± 20° C), apparently reflect leakage of inclusions along subgrain boundaries. Minimum Th values (120-160°C), on the other hand, record near lithostatic conditions (2.6 kb) at 300°C. Maximum last melting temperatures ( Tm) increase from -20 to -4°C with decreasing distance to the thrust, corresponding to a decrease in salinity of the fluid from 23 to 3 wt% (NaCl equivalent). The decrease in salinity towards the fault is interpreted as due to infiltration of the fault at depth (to approximately 10 km) by surface derived waters during periods of fault zone dilatancy. Inclusions along healed microcracks in quartz from the fault zone display higher salinity (17-26 wt% NaCl equiv.) and are interpreted to reflect enhanced fluid-rock interaction in the fault zone due to hydration reactions. The fluid pressure and salinity variations are consistent with a combined dilatancy-hydraulic fracturing model for the Rector Branch thrust. Previously documented bulk rock volume losses for this fault zone are inferred to have been produced by the fluxing of the fault zone with undersaturated surface derived fluids.

  10. Anomalous scattering behavior of selected impact parabola features: Magellan cycle-to-cycle comparisons

    NASA Technical Reports Server (NTRS)

    Plaut, Jeffrey J.; Saunders, R. Stephen; Stofan, E. R.; Kirk, R. L.; Schaber, G. G.; Soderblom, L. A.; Ford, P. G.; Pettengill, G. H.; Campbell, D. B.; Stacy, N. J. S.

    1992-01-01

    Magellan observations indicate that many venusian impact craters have associated surfaces, typically lower in backscatter and emissivity than the surroundings, that extend up to hundreds of kilometers to the west of craters, in parabolic planforms. During Magellan's second mapping cycle, a number of these parabolic features were imaged for a second time, under a different viewing geometry. In some cases, the SAR backscatter appearance of portions of the parabolic features was quite different in the two datasets. We present a description and preliminary interpretations of the anomalous appearance of these features as observed during Magellan's first and second mapping cycles.

  11. Computation of time-dependent subsurface pore pressure variations and stresses due to time varying water loads at the Itoiz reservoir (Northern Spain), and their relation with near seismicity

    NASA Astrophysics Data System (ADS)

    Luzón, F.; García-Jerez, A.; Santoyo, M. A.

    2009-04-01

    In this work we study the seismicity produced near the newly constructed Itoiz reservoir in the western Pyrenees (northern Spain). We computed the evolution of the stress changes in the subsoil due to the time water load distribution and relate it with the main seismicity occurred after the beginning of impoundment in 2004. We also computed the pore pressure variations produced around Itoiz dam using a hybrid technique which take into account the time varying water loads in the reservoir. In this methodology, two different techniques are joined to calculate each one of the partial solutions evolved: the pore pressure diffusion term is obtained by using the Green functions of the problem, whereas the second term due to stress time changes is computed with a Finite Difference Method (FDM). We pay special attention to the pore pressure changes at the hypocenter location of the mainshock (with magnitude mb = 4.6) occurred on September 2004, 8 months after the beginning of its impounding. After this, we compute the coseismic and postseismic stress changes produced by the main events of the seismic series and study its influence on the triggering of the aftershocks by means of the Coulomb Failure Stress criterion (ΔCFS). Results show that at the time of occurrence of the main earthquake the pore pressure change was of about 1000 Pa at the hypocenter. However, the pore pressure variation exceeded 1000 Pa at other earlier times and at many different positions near Itoiz dam without the occurrence of earlier earthquakes. Thus, the origin of the September 18, 2004 earthquake (mb = 4.6) can be explained when considering the pore pressure perturbation at a pre-existent fault in the hypocenter location with more aptitude to fail than other sites, together with the assumption of regional pre-existing stress field. At last we found, a large positive influence over most of the aftershocks of the seismic series due to the stress changes produced by the largest events.

  12. Interfacial heat transfer in squeeze casting of magnesium alloy AM60 with variation of applied pressures and casting wall-thicknesses

    NASA Astrophysics Data System (ADS)

    Zhang, Xuezhi; Fang, Li; Sun, Zhizhong; Hu, Henry; Nie, Xueyuan; Tjong, Jimi

    2015-12-01

    The heat transfer coefficient at the casting-die interface is the most important factor on the solidification process. With the 75-ton hydraulic press machine and P20 steel die mold, 5-step castings of magnesium alloy AM60 with different wall-thicknesses (3, 5, 8, 12, 20 mm) were poured under various hydraulic pressures (30, 60, and 90 MPa) using an indirect squeeze casting process. Thermal histories throughout the die wall and the casting surface have been recorded by fine type-K thermocouples. The in-cavity local pressures measured by pressure transducers were explored at the casting-die interfaces of 5 steps. The casting-die interfacial heat transfer coefficients (IHTC) initially reached a maximum peak value followed by a gradually decline to the lower level. Similar characteristics of IHTC peak values can be observed at the applied pressures of 30, 60 and 90 MPa. With the applied pressure of 90 MPa, the peak IHTC values from steps 1 to 5 varied from 5623 to 10,649 W/m2 K. As the applied hydraulic pressure increased, the IHTC peak value of each step was increased accordingly. The wall thickness also affected IHTC peak values significantly. The peak IHTC value and heat flux increased as the step became thicker. The empirical equations relating the IHTCs to the local pressures and the solidification temperature at the casting surface were developed based on the multivariate linear and polynomial regression.

  13. Determination of the variation of the fluorescence line positions of ruby, strontium tetraborate, alexandrite, and samarium-doped yttrium aluminum garnet with pressure and temperature

    NASA Astrophysics Data System (ADS)

    Raju, Selva Vennila; Zaug, Joseph M.; Chen, Bin; Yan, Jinyuan; Knight, Jason W.; Jeanloz, Raymond; Clark, Simon M.

    2011-07-01

    The pressure and temperature dependent fluorescence line-shift of strontium tetraborate has been measured concurrently with x-ray diffraction from the pressure standards sodium chloride or gold. Temperature was found to have a small effect on the fluorescence line-shift under pressure. We found a maximum pressure uncertainty of ±1.8 GPa at 25 GPa (7.2%) and 857 K when making no temperature correction. The fluorescence line-shifts for ruby, Alexandrite, and samarium-doped yttrium aluminum garnet were also determined, using our strontium tetraborate calibration to determine pressure and a thermocouple to measure temperature. Fluorescence measurements were extended up to 800 K for ruby and Alexandrite. Temperature was found to have a small effect on the fluorescence line-shift of samarium-doped yittrium aluminum garnet. We found a maximum uncertainty of ±2.7 GPa at 25 GPa (11.1%) and 857 K when no temperature correction was applied. We determined equations relating to the fluorescence line position from these data, which include a cross derivative term to account for the combined effect of pressure and temperature. We present a method to independently determine pressure and/or temperature from combined fluorescence line-shift measurements of a pair of optical sensors.

  14. Yearly variation of bacterial production in the Arraial do Cabo protection area (Cabo Frio upwelling region): An evidence of anthropogenic pressure

    PubMed Central

    Coelho-Souza, Sérgio A.; Pereira, Gilberto C.; Coutinho, Ricardo; Guimarães, Jean R.D.

    2013-01-01

    Arraial do Cabo is where upwelling occurs more intensively on the Brazilian coast. Although it is a protection area it suffers anthropogenic pressure such as harbor activities and sporadic sewage emissions. Short-time studies showed a high variability of bacterial production (BP) in this region but none of them evaluated BP during long periods in a large spatial scale including stations under different natural (upwelling and cold fronts) and anthropogenic pressures. During 2006, we sampled surface waters 10 times (5 in upwelling and 5 in subsidence periods) in 8 stations and we measured BP, temperature as well as the concentrations of inorganic nutrients, pigments and particulate organic matter (POM). BP was up to 400 times higher when sewage emissions were observed visually and it had a positive correlation with ammonia concentrations. Therefore, in 2007, we did two samples (each during upwelling and subsidence periods) during sewage emissions in five stations under different anthropogenic pressure and we also measured particles abundance by flow cytometry. The 12 samples in the most impacted area confirmed that BP was highest when ammonia was higher than 2 μM, also reporting the highest concentrations of chlorophyll a and suspended particles. However, considering all measured variables, upwelling was the main disturbing factor but the pressure of fronts should not be neglected since it had consequences in the auto-heterotrophic coupling, increasing the concentrations of non fluorescent particles and POM. Stations clustered in function of natural and anthropogenic pressures degrees and both determined the temporal-spatial variability. PMID:24688533

  15. Predicting pressure-dependent unimolecular rate constants using variational transition state theory with multidimensional tunneling combined with system-specific quantum RRK theory: a definitive test for fluoroform dissociation.

    PubMed

    Bao, Junwei Lucas; Zhang, Xin; Truhlar, Donald G

    2016-06-22

    Understanding the falloff in rate constants of gas-phase unimolecular reaction rate constants as the pressure is lowered is a fundamental problem in chemical kinetics, with practical importance for combustion, atmospheric chemistry, and essentially all gas-phase reaction mechanisms. In the present work, we use our recently developed system-specific quantum RRK theory, calibrated by canonical variational transition state theory with small-curvature tunneling, combined with the Lindemann-Hinshelwood mechanism, to model the dissociation reaction of fluoroform (CHF3), which provides a definitive test for falloff modeling. Our predicted pressure-dependent thermal rate constants are in excellent agreement with experimental values over a wide range of pressures and temperatures. The present validation of our methodology, which is able to include variational transition state effects, multidimensional tunneling based on the directly calculated potential energy surface along the tunneling path, and torsional and other vibrational anharmonicity, together with state-of-the-art reaction-path-based direct dynamics calculations, is important because the method is less empirical than models routinely used for generating full mechanisms, while also being simpler in key respects than full master equation treatments and the full reduced falloff curve and modified strong collision methods of Troe. PMID:27273734

  16. SENSITIVITY OF THE HOUSE PRESSURE TEST FOR DUCT LEAKAGE TO VARIATIONS IN THE DISTRIBUTION OF AIR LEAKAGE IN THE HOUSE ENVELOPE

    SciTech Connect

    ANDREWS,J.W.

    1998-12-01

    The house pressure test for air leakage in ducts calculates the signed difference between the supply and return leakage from the response of the air pressure in the house to operation of the system fan. The currently accepted version of this calculation was based on particular assumptions about how the house envelope leakage is distributed between the walls, ceiling, and floor. This report generalizes the equation to account for an arbitrary distribution of envelope leakage. It concludes that the currently accepted equation is usually accurate to within {+-}5%, but in a small proportion of cases the results may diverge by 50% or more.

  17. Sensitivity of the house pressure test for duct leakage to variations in the distribution of air leakage in the house envelope

    SciTech Connect

    Andrews, J.W.

    1998-12-01

    The house pressure test for air leakage in ducts calculates the signed difference between the supply and return leakage from the response of the air pressure in the house to operation of the system fan. The currently accepted version of this calculation was based on particular assumptions about how the house envelope leakage is distributed between the walls, ceiling, and floor. This report generalizes the equation to account for an arbitrary distribution of envelope leakage. It concludes that the currently accepted equation is usually accurate to within {+-}5%, but in a small proportion of cases the results may diverge by 50% or more.

  18. Spatial and Temporal Variations in the Partial Pressure and Emission of CO2 and CH4 in and Amazon Floodplain Lake

    NASA Astrophysics Data System (ADS)

    Forsberg, B. R.; Amaral, J. H.; Barbosa, P.; Kasper, D.; MacIntyre, S.; Cortes, A.; Sarmento, H.; Borges, A. V.; Melack, J. M.; Farjalla, V.

    2015-12-01

    The Amazon floodplain contains a variety of wetland environments which contribute CO2 and CH4 to the regional and global atmospheres. The partial pressure and emission of these greenhouse gases (GHGs) varies: 1) between habitats, 2) seasonally, as the characteristics these habitats changes and 3) diurnally, in response to diurnal stratification. In this study, we investigated the combined influence of these factors on the partial pressure and emission of GHGs in Lago Janauacá, a central Amazon floodplain lake (3o23' S; 60o18' O). All measurements were made between August of 2014 and April of 2015 at two different sites and in three distinct habitats: open water, flooded forest, flooded macrophytes. Concentrations of CO2 and CH4 in air were measured continuously with a cavity enhanced absorption spectrometer, Los Gatos Research´s Ultraportable Greenhouse Gas Analyzer (UGGA). Vertical profiles o pCO2 and pCH4 were measured using the UGGA connected to an electric pump and equilibrator. Diffusive surface emissions were estimated with the UGGA connected to a static floating chamber. To investigate the influence of vertical stratification and mixing on GHG partial pressure and emissions, a meteorological station and submersible sensor chain were deployed at each site. Meteorological sensors included wind speed and direction. The submersible chains included thermistors and oxygen sensors. Depth profiles of partial pressure and diffusive emissions for both CO2 and CH4 varied diurnally, seasonally and between habitats. Both pCO2 and pCH4 were consistently higher in bottom than surface waters with the largest differences occurring at high water when thermal stratification was most stable. Methane emissions and partial pressures were highest at low water while pCO2 and CO2 fluxes were highest during high water periods, with 35% of CO2 fluxes at low water being negative. The highest average surface value of pCO2 (5491 μatm), encountered during rising water, was ~3 times

  19. Magnetic activity of red secondaries: clues from the outburst cycle variations of dwarf novae

    NASA Astrophysics Data System (ADS)

    Chinarova, L. L.

    Photometric variations of 6 dwarf novae stars are studied based on the photographic observations from the Odessa, Moscow and Sonneberg plate collections and published visual monitoring data from the AFOEV database (Schweitzer E.: 1993, Bull. AFOEV, 64, 14). The moments of maxima are determined by using the "running parabola" fit (Andronov I.L., 1990, Kinematika Fizika Nebesn. Tel., v.6,,N 6, 87) with automatically determined filter half-width (Andronov I.L., 1997, As.Ap. Suppl., in press). All investigated stars exhibit significant changes not only from cycle-to-cycle, but from season-to-season as well. Secondary decade-scale cycles of smooth variations (Bianchini A., 1990, AJ 99, 1941) and abrupt switchings (Andronov I.L., Shakun L.I., 1990, ASS 169, 237) were interpreted by a solar-type activity of the red dwarf secondary in a binary system and may argue for existence of two different subgroups of the dwarf novae.

  20. Structural Variations in β-(BDA-TTP)2FeCl4 at Low Temperature and under Pressure: Charge-Ordered State with a Two-Fold Crystal Structure

    NASA Astrophysics Data System (ADS)

    Sasamori, Kota; Takahashi, Kazuyuki; Kodama, Takeshi; Fujita, Wataru; Kikuchi, Koichi; Yamada, Jun-ichi

    2013-05-01

    The pressure-induced organic superconductor β-(BDA-TTP)2FeCl4 [BDA-TTP = 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene], which shows a metal--insulator (MI) transition at TMI = 113 K under ambient pressure, has been found by X-ray study to have a two-fold crystal structure along the c-axis in the insulating state at 10 K. In the donor layer, there are four independent BDA-TTP molecules, which are divided into two charge-poor ones and two charge-rich ones on the basis of the folding dihedral angles around the intramolecular sulfur-to-sulfur axes of two outer dithiane rings in BDA-TTP. The charge separation leads to the formation of two types of dimers: a dimer consisting of two charge-poor donors and a dimer consisting of two charge-rich ones. The tight-binding band calculation revealed a band gap of 5.3 meV in the energy dispersion. The MI transition can be therefore accounted for by the charge separation. In addition, we investigated the crystal and electronic structures of β-(BDA-TTP)2FeCl4 at different pressures up to 21 kbar, and found that the application of pressures causes variations in both the conformation of donor molecule and the donor arrangement, which are responsible for almost uniform interaction in the donor stacking and for an increase in bandwidth (W). As a result, the suppression of MI transition and subsequent occurrence of superconductivity in β-(BDA-TTP)2FeCl4 would be observed with increasing pressure.

  1. Should pulse pressure and day/night variations in blood pressure be seen as independent risk factors requiring correction or simply as markers to be taken into account when evaluating overall vascular risk?

    PubMed

    Bouhanick, B; Chamontin, B

    2007-11-01

    Patients with a blunted fall in nocturnal BP (known as non-dippers) have a high risk of micro- and macrovascular complications, particularly if they have hypertension, but also in normotensive patients with diabetes. A blunted fall in nocturnal BP reflects the high level of CV risk in these patients. ABPM data indicating an altered circadian BP rhythm reverse circadian BP profile should alert the physician to the potential risk of complications and should lead to efforts to treat hypertension effectively, especially at night, and to check for sleep apnoea syndrome, particularly in cases of resistant hypertension, or autonomic neuropathy (postural hypotension), a well known risk factor for cardiovascular (CV) events. Patients should be carefully screened for nephropathy. However, the definitions of "non-dipper" vary widely. Suitable treatments are poorly defined, but angiotensin-converting enzyme inhibitors (ACEi), diuretics, salt restriction and the maintenance of continuous positive airway pressure (CPAP) can be used as non-specific treatments. The efficacy of taking blood pressure-lowering drugs at bedtime rather than in the morning is still debated but deserves attention. In the diabetic population, brachial pulse pressure (PP) is an independent predictor of cardiovascular mortality, but not of all-cause mortality. It is also associated with complications of both type 2 and type 1 diabetes, this effect being stronger for nocturnal than for diurnal PP, and is strongly predictive of coronary heart disease in patients with type 2 diabetes. The stronger association between PP and age in diabetic than in non-diabetic populations suggests that diabetes accelerates vascular ageing. In patients with incipient nephropathy or overt renal failure, PP increases CV risk. However, misinterpretation could be related to confusion between brachial PP and central PP. The therapeutic implications of PP measurement remain poorly documented in diabetes. PMID:17936663

  2. Variations in Battery Life of a Heart—Lung Machine Using Different Pump Speeds, Pressure Loads, Boot Material, Centrifugal Pump Head, Multiple Pump Usage, and Battery Age

    PubMed Central

    Marshall, Cornelius; Hargrove, Martin; O’Donnell, Aonghus; Aherne, Thomas

    2005-01-01

    Abstract: Electrical failure during cardiopulmonary bypass (CPB) has previously been reported to occur in 1 of every 1500 cases. Most heart—lung machine pump consoles are equipped with built-in battery back-up units. Battery run times of these devices are variable and have not been reported. Different conditions of use can extend battery life in the event of electrical failure. This study was designed to examine the run time of a fully charged battery under various conditions of pump speed, pressure loads, pump boot material, multiple pump usage, and battery life. Battery life using a centrifugal pump also was examined. The results of this study show that battery life is affected by pump speed, circuit pressure, boot stiffness, and the number of pumps in service. Centrifugal pumps also show a reduced drain on battery when compared with roller pumps. These elements affect the longevity and performance of the battery. This information could be of value to the individual during power failure as these are variables that can affect the battery life during such a challenging scenario. PMID:16350380

  3. A concept for transition mapping on a 10 deg-cone in the National Transonic Facility using flow-pressure variation

    NASA Technical Reports Server (NTRS)

    Gartenberg, Ehud

    1995-01-01

    A conceptual study was performed to define a technique for mapping the boundary-layer transition on a 10 deg-Cone in the National Transonic Facility (NTF) as a means of determining this cryogenic-tunnel suitability for laminar flow testing. A major challenge was to devise a test matrix using a fixed surface pitot probe, varying the flow pressure to pr oduce the actual Reynolds numbers for boundary-layer transition. This constraint resulted from a lack of a suitable and reliable electrical motor to drive the probe along the cone's surface under cryogenic flow conditions. The initial phase of this research was performed by the author in collaboration with the late Dr. William B. Igoe from the Aerodynamics Division at NASA Langley Research Center. His comments made during the drafting of this document were invaluable and a source of inspiration.

  4. Flow-compensating pressure regulator

    NASA Technical Reports Server (NTRS)

    Baehr, E. F.

    1979-01-01

    Pressure regulator developed for use with cataract-surgery instrument controls intraocular pressure during substantial variations in flow rate of infusion fluid. Device may be applicable to variety of eye-surgery instruments.

  5. Cu mesh's super-hydrophobic and oleophobic properties with variations in gravitational pressure and surface components for oil/water separation applications

    NASA Astrophysics Data System (ADS)

    Guo, Wei; Zhang, Qin; Xiao, Haibo; Xu, Jie; Li, Qintao; Pan, Xiaohui; Huang, Zhiyong

    2014-09-01

    The super-hydrophobic and super-oleophilic properties of various materials have been utilized to separate oil from water. These properties induce both oil penetration and water slide off. This research demonstrates that the mesh with both super-hydrophobic and oleophobic properties, with a water contact angle (WCA) higher than 150° and oil contact angle (OCA) near 140°, can also be used to separate oil from. Oil has a higher probability than water of entering into the interstice of the Cu mesh surface and passing through it due to the capillarity effect, van der Waals attractions and the effects of gravitational pressure. The modified mesh surface can easily adsorb the oil, which then forms a film, due to the very strong adhesion properties of the oil molecules. The oil film then contributes to the water sliding off. These properties can be used to separate oil from water with separation efficiencies reaching 99.3%. Additionally, the separation of an oil/water mixture using sand permeated with oil yielded separation efficiencies exceeding 90%.

  6. Application of thermodynamic modelling to natural mantle xenoliths: examples of density variations and pressure-temperature evolution of the lithospheric mantle

    NASA Astrophysics Data System (ADS)

    Ziberna, L.; Klemme, S.

    2016-02-01

    In this paper, we show how the results of phase equilibria calculations in different mantle compositions can be reconciled with the evidence from natural mantle samples. We present data on the response of bulk rock density to pressure (P), temperature (T) and compositional changes in the lithospheric mantle and obtain constraints on the P-T evolution recorded by mantle xenoliths. To do this, we examine the mantle xenolith suite from the Quaternary alkali basalts of Pali-Aike, Patagonia, using phase equilibria calculation in six representative compositions. The calculations were done subsolidus and in volatile-free conditions. Our results show that the density change related to the spinel peridotite to garnet peridotite transition is not sharp and strongly depends on the bulk composition. In a depleted mantle composition, this transition is not reflected in the density profile, while in a fertile mantle it leads to a relative increase in density with respect to more depleted compositions. In mantle sections characterized by hot geothermal gradients (~70 mW/m2), the spinel-garnet transition may overlap with the lithosphere-asthenosphere boundary. Phase equilibria calculations in peridotitic compositions representative of the Pali-Aike mantle were also used to constrain the origin and evolution of the mantle xenoliths. Our results indicate that the mineral modes and compositions, and the mineral zonation reported for the low-temperature peridotites (spinel and spinel + garnet harzburgites and lherzolites), are linked to a cooling event in the mantle which occurred long before the eruption of the host basalts. In addition, our phase equilibria calculations show that kelyphitic rims around garnets, as those observed in the high-temperature garnet peridotites from Pali-Aike, can be explained simply by decompression and do not require additional metasomatic fluid or melt.

  7. Haplotypes of the WNK1 gene associate with blood pressure variation in a severely hypertensive population from the British Genetics of Hypertension study.

    PubMed

    Newhouse, Stephen J; Wallace, Chris; Dobson, Richard; Mein, Charles; Pembroke, Janine; Farrall, Martin; Clayton, David; Brown, Morris; Samani, Nilesh; Dominiczak, Anna; Connell, John M; Webster, John; Lathrop, G Mark; Caulfield, Mark; Munroe, Patricia B

    2005-07-01

    Mutations in the WNK1 gene cause Gordon's syndrome, a rare Mendelian form of hypertension. We assessed whether common WNK1 variants might also contribute to essential hypertension (EH), a multifactorial disorder affecting > 25% of the adult population worldwide. A panel of 19 single nucleotide polymorphisms (SNPs) spanning the gene was selected from public databases and was genotyped in 100 white European families to determine the pattern of linkage disequilibrium, haplotype structure and tagging SNPs for the WNK1 locus. Eight tagging SNPs were identified with 90% power to predict common WNK1 haplotypes and SNPs. Family-based association tests were used to test for association with EH and severity of hypertension in 712 severely hypertensive families from the MRC British Genetics of Hypertension study resource. No association was found between WNK1 polymorphisms or haplotypes with hypertension; however, one SNP rs1468326, located 3 kb from the WNK1 promoter, was found to be nominally associated with severity of hypertension, with both systolic blood pressure (BP) (Z = +2.24, P = 0.025) and diastolic BP (Z = +1.99, P = 0.046). We also found nominal support for association of one common WNK1 haplotype with increased systolic BP (Z = +1.91, P = 0.053). This is the first study to perform haplotype association analysis of the WNK1 gene with EH. This finding of association between a SNP near the promoter region and the severity of hypertension suggests that increased expression of WNK1 might contribute to BP variability and susceptibility to EH similar to the mechanism of hypertension observed in Gordon's syndrome. PMID:15888480

  8. Blood pressure self-surveillance for health also reflects 1.3-year Richardson solar wind variation: spin-off from chronomics.

    PubMed

    Halberg, Franz; Cornélissen, Germaine; Schack, Barbara; Wendt, Hans W; Minne, Hélène; Sothern, Robert B; Watanabe, Yoshihiko; Katinas, George; Otsuka, Kuniaki; Bakken, Earl E

    2003-10-01

    Self-experimentation concerns not only scientists, but also each individual for the sake of his/her chronobiologic health and science literacy, eventually to be acquired in primary and secondary education. Public education ensures that everybody who knows how to read or write can dispense with the service of a costly scribe. At all ages, public education can teach equally well how to find out whether one's blood pressure (BP) and heart rate (HR) responds to an increase in sodium intake with a rise, with no change or with a decrease in BP. This task and many others could become a matter of informed self-surveillance. Whenever there are inter-individual, sometimes opposite differences in response, government-sponsored trials on groups that do not consider such differences cannot solve what only the individual can do, at first by help from schools. Eventually special institutions may be designed for chronomics, the monitoring, interpretation and archivization of chronomes (time structures; from chronos = time and nomos = rule) of biological variables, also charged with a demographic analyzing and reporting system. Each individual's properly coded record, to guard confidentiality, becomes part of a promptly accessible database for one's own needs and for society's requirements. What individuals and small groups started as chronobiology, what is immediately available on back burners, as a service by an international project on the biosphere and the cosmos (BIOCOS) (corne001@umn.edu) could become a public system of planned surveillance archivization of one's rhythms from womb to tomb. Alterations of a rhythm's amplitude or acrophase or of a deterministic or other chaotic endpoint, such as a correlation dimension and approximate entropy, or of a standard deviation, among a multitude of other endpoints, can signal (in the otherwise neglected normal range) reversible risk elevations. If these elevated risks are detected and prompt the institution of countermeasures, such

  9. Fuzzy blood pressure measurement

    NASA Astrophysics Data System (ADS)

    Cuce, Antonino; Di Guardo, Mario; Sicurella, Gaetano

    1998-10-01

    In this paper, an intelligent system for blood pressure measurement is posed together with a possible implementation using an eight bit fuzzy processor. The system can automatically determine the ideal cuff inflation level eliminating the discomfort and misreading caused by incorrect cuff inflation. Using statistics distribution of the systolic and diastolic blood pressure, in the inflation phase, a fuzzy rule system determine the pressure levels at which checking the presence of heart beat in order to exceed the systolic pressure with the minimum gap. The heart beats, characterized through pressure variations, are recognized by a fuzzy classifier.

  10. Predictive modeling and reducing cyclic variability in autoignition engines

    DOEpatents

    Hellstrom, Erik; Stefanopoulou, Anna; Jiang, Li; Larimore, Jacob

    2016-08-30

    Methods and systems are provided for controlling a vehicle engine to reduce cycle-to-cycle combustion variation. A predictive model is applied to predict cycle-to-cycle combustion behavior of an engine based on observed engine performance variables. Conditions are identified, based on the predicted cycle-to-cycle combustion behavior, that indicate high cycle-to-cycle combustion variation. Corrective measures are then applied to prevent the predicted high cycle-to-cycle combustion variation.

  11. Pressurized liquid filled tendons

    SciTech Connect

    Burns, G.E.

    1987-05-12

    This patent describes an apparatus for detecting a leak in a tension leg platform tendon, comprising: a fluid-tight tensioned tubular tendon, the tendon connected on its upper end to a buoyant offshore structure and on its lower end to an anchor means. The anchor means is connected to the sea floor; means for supplying liquid to the tendon; means for pressurizing the liquid in excess of the maximum hydrostatic pressure exerted by the sea water on the tendon; and means for monitoring pressure, the means monitoring variations in liquid pressure to the tendon.

  12. X-ray Monitoring of eta Carinae: Variations on a Theme

    NASA Technical Reports Server (NTRS)

    Corcoran, M. F.

    2004-01-01

    We present monitoring observations by the Rossi X-ray Timing Explorer of the 2-10 keV X-ray emission from the supermassive star eta Carinae from 1996 through late 2003. These data cover more than one of the stellar variability cycles in temporal detail and include especially detailed monitoring through two X-ray minima. We compare the current X-ray minimum which began on June 29, 2003 to the previous X-ray minimum which began on December 15, 1997, and refine the X-ray period to 2024 days. We examine the variations in the X-ray spectrum with phase and with time, and also refine our understanding of the X-ray peaks which have a quasi-period of 84 days, with significant variation. Cycle-to-cycle differences are seen in the level of X-ray intensity and in the detailed variations of the X-ray flux on the rise to maximum just prior to the X-ray minimum. Despite these differences the similarities between the decline to minimum, the duration of the minimum, and correlated variations of the X-ray flux and other measures throughout the electromagnetic spectrum leave little doubt that that the X-ray variation is strictly periodic and produced by orbital motion as the wind from eta Carinae collides with the wind of an otherwise unseen companion.

  13. Blood pressure

    MedlinePlus Videos and Cool Tools

    Normal blood pressure is important for proper blood flow to the body’s organs and tissues. The force of the blood on the walls of the arteries is called blood pressure. Blood pressure is measured both as the heart ...

  14. Blood pressure

    MedlinePlus Videos and Cool Tools

    Normal blood pressure is important for proper blood flow to the body’s organs and tissues. The force of the blood on the walls of the arteries is called blood pressure. Blood pressure is measured both ...

  15. Atmospheric Pressure During Landing

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This figure shows the variation with time of pressure (dots) measured by the Pathfinder MET instrument during the landing period shown in image PIA00797. The two diamonds indicate the times of bridal cutting and 1st impact. The overall trend in the data is of pressure increasing with time. This is almost certainly due to the lander rolling downhill by roughly 10 m. The spacing of the horizontal dotted lines indicates the pressure change expected from 10 m changes in altitude. Bounces may also be visible in the data.

  16. Shoulder Pain and Cycle to Cycle Kinematic Spatial Variability during Recovery Phase in Manual Wheelchair Users: A Pilot Investigation

    PubMed Central

    Jayaraman, Chandrasekaran; Moon, Yaejin; Rice, Ian M.; Hsiao Wecksler, Elizabeth T.; Beck, Carolyn L.; Sosnoff, Jacob J.

    2014-01-01

    Wheelchair propulsion plays a significant role in the development of shoulder pain in manual wheelchair users (MWU). However wheelchair propulsion metrics related to shoulder pain are not clearly understood. This investigation examined intra-individual kinematic spatial variability during semi-circular wheelchair propulsion as a function of shoulder pain in MWU. Data from 10 experienced adult MWU with spinal cord injury (5 with shoulder pain; 5 without shoulder pain) were analyzed in this study. Participants propelled their own wheelchairs on a dynamometer at 3 distinct speeds (self-selected, 0.7 m/s, 1.1 m/s) for 3 minutes at each speed. Motion capture data of the upper limbs were recorded. Intra-individual kinematic spatial variability of the steady state wrist motion during the recovery phase was determined using principal component analysis (PCA). The kinematic spatial variability was calculated at every 10% intervals (i.e at 11 interval points, from 0% to 100%) along the wrist recovery path. Results Overall, spatial variability was found to be highest at the start and end of the recovery phase and lowest during the middle of the recovery path. Individuals with shoulder pain displayed significantly higher kinematic spatial variability than individuals without shoulder pain at the start (at 10% interval) of the recovery phase (p<.004). Conclusions Analysis of intra-individual kinematic spatial variability during the recovery phase of manual wheelchair propulsion distinguished between those with and without shoulder pain. Variability analysis of wheelchair propulsion may offer a new approach to monitor the development and rehabilitation of shoulder pain. PMID:24614232

  17. Pressure Sores

    MedlinePlus

    ... may form. Pressure sores are also called bedsores, pressure ulcers and decubitus ulcers. Symptoms What are the symptoms ... do to help pressure sores heal: Relieving the pressure that caused the sore Treating the sore itself Improving nutrition and other conditions to help the sore heal ...

  18. Characterization of the flowing afterglows of an N2 O2 reduced-pressure discharge: setting the operating conditions to achieve a dominant late afterglow and correlating the NOβ UV intensity variation with the N and O atom densities

    NASA Astrophysics Data System (ADS)

    Boudam, M. K.; Saoudi, B.; Moisan, M.; Ricard, A.

    2007-03-01

    The flowing afterglow of an N2-O2 discharge in the 0.6-10 Torr range is examined in the perspective of achieving sterilization of medical devices (MDs) under conditions ensuring maximum UV intensity with minimum damage to polymer-based MDs. The early afterglow is shown to be responsible for creating strong erosion damage, requiring that the sterilizer be operated in a dominant late-afterglow mode. These two types of afterglow can be characterized by optical emission spectroscopy: the early afterglow is distinguished by an intense emission from the N_{2}^{+} 1st negative system (band head at 391.4 nm) while the late afterglow yields an overpopulation of the v' = 11 ro-vibrational level of the N2(B) state, indicating a reduced contribution from the early afterglow N2 metastable species. We have studied the influence of operating conditions (pressure, O2 content in the N2-O2 mixture, distance of the discharge from the entrance to the afterglow (sterilizer) chamber) in order to achieve a dominant late afterglow that also ensures maximum and almost uniform UV intensity in the sterilization chamber. As far as operating conditions are concerned, moving the plasma source sufficiently far from the chamber entrance is shown to be a practical means for significantly reducing the density of the characteristic species of the early afterglow. Using the NO titration method, we obtain the (absolute) densities of N and O atoms in the afterglow at the NO injection inlet, a few cm before the chamber entrance: the N atom density goes through a maximum at approximately 0.3-0.5% O2 and then decreases, while the O atom density increases regularly with the O2 percentage. The spatial variation of the N atom (relative) density in the chamber is obtained by recording the emission intensity from the 1st positive system at 580 nm: in the 2-5 Torr range, this density is quite uniform everywhere in the chamber. The (relative) densities of N and O atoms in the discharge are determined by using

  19. Estimation of trapped mass by in-cylinder pressure resonance in HCCI engines

    NASA Astrophysics Data System (ADS)

    Luján, José Manuel; Guardiola, Carlos; Pla, Benjamín; Bares, Pau

    2016-01-01

    High pressure gradients at homogeneous charge compression ignition (HCCI) engines heavily excite the pressure resonance. The pressure resonant frequency depends on speed of sound in the cylinder, and thus on the bulk gas temperature. Present paper profits this relation estimating the trapped mass inside the cylinder. In contrast to other estimation methods in the literature, the presented method is based on the trace of the in-cylinder pressure during the cycle; therefore, it permits a cycle-to-cycle mass estimation, and avoids errors associated with other assumptions, such as heat transfer during compression or initial temperature of the in-cylinder gases. The proposed strategy only needs the pressure signal, a volume estimation and a composition assumption to obtain several trapped mass estimates during one cycle. These estimates can be later combined for providing an error estimate of the measurement, with the assumption of negligible blow-by. The method is demonstrated in two HCCI engines of different size, showing good performance in steady operation and presenting great potential to control transient operation.

  20. Thermodynamic equilibrium at heterogeneous pressure

    NASA Astrophysics Data System (ADS)

    Vrijmoed, Johannes C.; Podladchikov, Yuri Y.

    2014-05-01

    Recent advances in metamorphic petrology point out the importance of grain-scale pressure variations in high-temperature metamorphic rocks. Pressures derived from chemical zonation using unconventional geobarometry based on equal chemical potentials fit mechanically feasible pressure variations. Here a thermodynamic equilibrium method is presented that predicts chemical zoning as a result of pressure variations by Gibbs energy minimization. Equilibrium thermodynamic prediction of the chemical zoning in the case of pressure heterogeneity is done by constraint Gibbs minimization using linear programming techniques. Compositions of phases considered in the calculation are discretized into 'pseudo-compounds' spanning the entire compositional space. Gibbs energies of these discrete compounds are generated for a given range and resolution of pressures for example derived by barometry or from mechanical model predictions. Gibbs energy minimization is subsequently performed considering all compounds of different composition and pressure. In addition to constraining the system composition a certain proportion of the system is constraint at a specified pressure. Input pressure variations need to be discretized and each discrete pressure defines an additional constraint for the minimization. The proportion of the system at each different pressure is equally distributed over the number of input pressures. For example if two input pressures P1 and P2 are specified, two constraints are added: 50 percent of the system is constraint at P1 while the remaining 50 percent is constraint at P2. The method has been tested for a set of 10 input pressures obtained by Tajčmanová et al. (2014) using their unconventional geobarometry method in a plagioclase rim around kyanite. Each input pressure is added as constraint to the minimization (1/10 percent of the system for each discrete pressure). Constraining the system composition to the average composition of the plagioclase rim

  1. Pressure ulcers.

    PubMed

    O'Byrne, Deborah

    2016-04-13

    My nursing experience is in acute care. Acute medical nurses are well placed to assess skin integrity, identify patients at risk of pressure ulcer development, and commence appropriate interventions to prevent or treat pressure ulcers. PMID:27073966

  2. Pressure Sores

    MedlinePlus

    Pressure sores are areas of damaged skin caused by staying in one position for too long. They ... wheelchair, or are unable to change your position. Pressure sores can cause serious infections, some of which ...

  3. Pressure-driven peristaltic flow

    NASA Astrophysics Data System (ADS)

    Mingalev, S. V.; Lyubimov, D. V.; Lyubimova, T. P.

    2013-03-01

    The peristaltic motion of an incompressible fluid in two-dimensional channel is investigated. Instead of fixing the law of wall's coordinate variation, the law of pressure variation on the wall is fixed and the border's coordinate changes to provide the law of pressure variation on the wall. In case of small amplitude of pressure-variation on the wall A, expansion wave propagates along the length of channel and the wave results in the peristaltic transport of fluid. In the case of large A, the channel divides into two parts. The small pulsating part in the end of the tube creates the flow as a human heart, while the other big part loses this function. The solution of problem for the first peristaltic mode is stable, while the solution for the second "heart" mode is unstable and depends heavily on boundary conditions.

  4. Pressure Controller

    NASA Astrophysics Data System (ADS)

    1981-01-01

    EPIC is Electronic Pressure Indicating Controller produced by North American Manufacturing Company. It is a high-sensitivity device for improving combustion efficiency in industrial furnaces that interprets a signal from a pressure transducer on a furnace and regulates furnace pressure accordingly. A controller can provide savings of from five to 25 percent of an industrial user's annual furnace fuel bill.

  5. Barometric pressure

    NASA Technical Reports Server (NTRS)

    Billings, C. E.

    1973-01-01

    The effects of alterations in barometric pressure on human beings are described. Human tolerances for gaseous environments and low and high barometric pressure are discussed, including effects on specific areas, such as the ear, lungs, teeth, and sinuses. Problems due to trapped gas within the body, high dynamic pressures on the body, and blasts are also considered.

  6. The vapor pressures of explosives

    SciTech Connect

    Ewing, Robert G.; Waltman, Melanie J.; Atkinson, David A.; Grate, Jay W.; Hotchkiss, Peter

    2013-01-05

    The vapor pressures of many explosive compounds are extremely low and thus determining accurate values proves difficult. Many researchers, using a variety of methods, have measured and reported the vapor pressures of explosives compounds at single temperatures, or as a function of temperature using vapor pressure equations. There are large variations in reported vapor pressures for many of these compounds, and some errors exist within individual papers. This article provides a review of explosive vapor pressures and describes the methods used to determine them. We have compiled primary vapor pressure relationships traceable to the original citations and include the temperature ranges for which they have been determined. Corrected values are reported as needed and described in the text. In addition, after critically examining the available data, we calculate and tabulate vapor pressures at 25 °C.

  7. High-pressure microfluidics

    NASA Astrophysics Data System (ADS)

    Hjort, K.

    2015-03-01

    When using appropriate materials and microfabrication techniques, with the small dimensions the mechanical stability of microstructured devices allows for processes at high pressures without loss in safety. The largest area of applications has been demonstrated in green chemistry and bioprocesses, where extraction, synthesis and analyses often excel at high densities and high temperatures. This is accessible through high pressures. Capillary chemistry has been used since long but, just like in low-pressure applications, there are several potential advantages in using microfluidic platforms, e.g., planar isothermal set-ups, large local variations in geometries, dense form factors, small dead volumes and precisely positioned microstructures for control of reactions, catalysis, mixing and separation. Other potential applications are in, e.g., microhydraulics, exploration, gas driven vehicles, and high-pressure science. From a review of the state-of-art and frontiers of high pressure microfluidics, the focus will be on different solutions demonstrated for microfluidic handling at high pressures and challenges that remain.

  8. Pressure Measurement

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Pressure Systems, Inc.'s DPT 6400 is a system designed to increase productivity in industrial processes where there is a need for making multiple pressure measurements quickly and with high accuracy. It is applicable in controlling industrial processes in plants that are being upgraded to automated status. In order to automate such plants the pressures at the many loops must be measured, converted to digital information and transmitted to the plant's process control computer. The DPT 6400 serves that function. By employing solid-state pressure sensing transducers whose errors are automatically corrected by a microprocessor, it is capable of highly accurate pressure measurements. Basic DPT 6400 has 64 channels, but the system can be expanded to 256 channels by the addition of "slave" units.

  9. Pressure and temperature variation of the electrical conductivity of poly(propylene glycol) containing LiCF{sub 3}SO{sub 3}. Technical report, 1 June 1998--31 May 1999

    SciTech Connect

    Fontanella, J.J.

    1999-07-01

    Electrical conductivity, dielectric relaxation and DSC studies have been carried out on poly(propylene glycol) (PPG, average molecular weight 1025) and PPG containing LiCF{sub 3}SO{sub 3}. The complex impedance studies were made at frequencies from about 1 mHz to 100 MHz at pressures up to 0.3 GPa (3 kbar) over the temperature range 215--365 K. Both the complex impedance and DSC studies were carried out in vacuum or at atmospheric pressure over a temperature range of about 100--375K. The inadequacy of the widely used Vogel Tammann Filcher (VTF) or Williams Landel Ferry (WLF) equations to describe the vacuum electrical conductivity data is discussed. It is shown that the Bendler-Shlesinger (BENSH) formalism is a better representation of the data, particularly in the region close to the glass transition. The first pressure derivative of the electrical conductivity decreases strongly with temperature giving rise to a large decrease in the apparent activation volume as temperature increases.

  10. [Individual pressure tolerance--a "target" pressure?].

    PubMed

    Bogdănici, C; Vancea, P P

    1999-01-01

    In literature there are many meanings for the limit between normal and pathological intraocular pressure: "normative pressure", "critic pressure", "individual tolerance pressure" and "target pressure". The aim of this paper is to demonstrate that these terms are synonymous. PMID:10756882

  11. Pressure Drop

    NASA Technical Reports Server (NTRS)

    Lawson, Mike

    2010-01-01

    Mike Lawson briefly discussed pressure drop for aerospace applications and presented short stories about adventures experienced while working at NASA and General Dynamics, including exposure to technologies like the Crew and Equipment Translation Aid (CETA) cart and the SWME.

  12. Peer Pressure

    MedlinePlus

    ... and behaviors. This is often positive — it's human nature to listen to and learn from other people ... Responding to peer pressure is part of human nature — but some people are more likely to give ...

  13. Pressure sensor

    SciTech Connect

    Mee, David K.; Ripley, Edward B.; Nienstedt, Zachary C.; Nienstedt, Alex W.; Howell, Jr., Layton N.

    2015-09-29

    Disclosed is a passive, in-situ pressure sensor. The sensor includes a sensing element having a ferromagnetic metal and a tension inducing mechanism coupled to the ferromagnetic metal. The tension inducing mechanism is operable to change a tensile stress upon the ferromagnetic metal based on a change in pressure in the sensing element. Changes in pressure are detected based on changes in the magnetic switching characteristics of the ferromagnetic metal when subjected to an alternating magnetic field caused by the change in the tensile stress. The sensing element is embeddable in a closed system for detecting pressure changes without the need for any penetrations of the system for power or data acquisition by detecting changes in the magnetic switching characteristics of the ferromagnetic metal caused by the tensile stress.

  14. PRESSURE TRANSDUCER

    DOEpatents

    Sander, H.H.

    1959-10-01

    A pressure or mechanical force transducer particularly adaptable to miniature telemetering systems is described. Basically the device consists of a transistor located within a magnetic field adapted to change in response to mechanical force. The conduction characteristics of the transistor in turn vary proportionally with changes in the magnetic flux across the transistor such that the output (either frequency of amplitude) of the transistor circuit is proportional to mechanical force or pressure.

  15. Pressure regulator

    DOEpatents

    Ebeling, Jr., Robert W.; Weaver, Robert B.

    1979-01-01

    The pressure within a pressurized flow reactor operated under harsh environmental conditions is controlled by establishing and maintaining a fluidized bed of uniformly sized granular material of selected density by passing the gas from the reactor upwardly therethrough at a rate sufficient to fluidize the bed and varying the height of the bed by adding granular material thereto or removing granular material therefrom to adjust the backpressure on the flow reactor.

  16. Ambulatory blood pressure monitoring in hypertensive adolescents.

    PubMed

    Fixler, D E; Wallace, J M; Thornton, W E; Dimmitt, P

    1990-04-01

    The purpose of this study was to determine the ability of ambulatory blood pressure monitoring to identify youths with chronic blood pressure elevation. Nineteen adolescent boys were studied, ten had 5-year average systolic or diastolic pressures above the 95th percentile, nine had normal pressure. A Del Mar Avionics Pressurometer III system recorded an average of 121 readings on each subject. The coefficients of variation for pressure were similar for hypertensive and normotensive individuals. During classes, eight of the ten hypertensive youths had elevated pressures in over half of the measurements. Also during these classes eight of ten hypertensive boys had average systolic or diastolic pressure above the 95th percentile, whereas only one of nine normotensive boys had average pressures above this level. We suggest that schooltime ambulatory pressures may be most useful in classifying the blood pressure trend in a youth. PMID:2346634

  17. High Blood Pressure

    MedlinePlus

    ... version High Blood Pressure Overview What is blood pressure? Blood pressure is the amount of force that your ... called your blood pressure. What is high blood pressure? High blood pressure (also called hypertension) occurs when your blood ...

  18. Pressure Inactivation of Bacillus Endospores

    PubMed Central

    Margosch, Dirk; Gänzle, Michael G.; Ehrmann, Matthias A.; Vogel, Rudi F.

    2004-01-01

    The inactivation of bacterial endospores by hydrostatic pressure requires the combined application of heat and pressure. We have determined the resistance of spores of 14 food isolates and 5 laboratory strains of Bacillus subtilis, B. amyloliquefaciens, and B. licheniformis to treatments with pressure and temperature (200 to 800 MPa and 60 to 80°C) in mashed carrots. A large variation in the pressure resistance of spores was observed, and their reduction by treatments with 800 MPa and 70°C for 4 min ranged from more than 6 log units to no reduction. The sporulation conditions further influenced their pressure resistance. The loss of dipicolinic acid (DPA) from spores that varied in their pressure resistance was determined, and spore sublethal injury was assessed by determination of the detection times for individual spores. Treatment of spores with pressure and temperature resulted in DPA-free, phase-bright spores. These spores were sensitive to moderate heat and exhibited strongly increased detection times as judged by the time required for single spores to grow to visible turbidity of the growth medium. The role of DPA in heat and pressure resistance was further substantiated by the use of the DPA-deficient mutant strain B. subtilis CIP 76.26. Taken together, these results indicate that inactivation of spores by combined pressure and temperature processing is achieved by a two-stage mechanism that does not involve germination. At a pressure between 600 and 800 MPa and a temperature greater than 60°C, DPA is released predominantly by a physicochemical rather than a physiological process, and the DPA-free spores are inactivated by moderate heat independent of the pressure level. Relevant target organisms for pressure and temperature treatment of foods are proposed, namely, strains of B. amyloliquefaciens, which form highly pressure-resistant spores. PMID:15574932

  19. Pressure-Letdown Plates for Coal Gasifiers

    NASA Technical Reports Server (NTRS)

    Collins, E. R., Jr.

    1985-01-01

    Variation of pseudoporous plates used with coal gasifiers in pressure letdown stage of processing minimize clogging. Rotating plates containing variable gap annuli continually change flow path to enable erosionless reduction of gas pressure. Particles that otherwise clog porous plugs pass through gaps.

  20. Induced topological pressure for topological dynamical systems

    SciTech Connect

    Xing, Zhitao; Chen, Ercai

    2015-02-15

    In this paper, inspired by the article [J. Jaerisch et al., Stochastics Dyn. 14, 1350016, pp. 1-30 (2014)], we introduce the induced topological pressure for a topological dynamical system. In particular, we prove a variational principle for the induced topological pressure.

  1. Pressure transducer

    DOEpatents

    Anderson, Thomas T.; Roop, Conard J.; Schmidt, Kenneth J.; Gunchin, Elmer R.

    1989-01-01

    A pressure transducer suitable for use in high temperature environments includes two pairs of induction coils, each pair being bifilarly wound together, and each pair of coils connected as opposite arms of a four arm circuit; an electrically conductive target moveably positioned between the coil pairs and connected to a diaphragm such that deflection of the diaphragm causes axial movement of the target and an unbalance in the bridge output.

  2. Pressure transducer

    DOEpatents

    Anderson, T.T.; Roop, C.J.; Schmidt, K.J.; Gunchin, E.R.

    1987-02-13

    A pressure transducer suitable for use in high temperature environments includes two pairs of induction coils, each pair being bifilarly wound together, and each pair of coils connected as opposite arms of a four arm circuit; an electrically conductive target moveably positioned between the coil pairs and connected to a diaphragm such that deflection of the diaphragm causes axial movement of the target and an unbalance in the bridge output. 7 figs.

  3. Solar cycle variations in the solar wind

    NASA Technical Reports Server (NTRS)

    Freeman, John W.; Lopez, Ramon E.

    1986-01-01

    The solar cycle variations of various solar wind parameters are reviewed. It is shown that there is a gradual decrease in the duration of high-speed streams from the declining phase of solar cycle 20 through the ascending phase of cycle 21 and a corresponding decrease in the annual average of the proton speed toward solar maximum. Beta, the ratio of the proton thermal pressure to magnetic pressure, undergoes a significant solar cycle variation, as expected from the variation in the IMF. Individual hourly averages of beta often exceed unity with 20 cases exceeding 10 and one case as high as 25. The Alfven Mach number shows a solar cycle variation similar to beta, lower aboard solar maximum. High-speed streams can be seen clearly in epsilon and the y component of the interplanetary magnetic field.

  4. Blood pressure measurement

    MedlinePlus

    Diastolic blood pressure; Systolic blood pressure; Blood pressure reading; Measuring blood pressure ... or your health care provider will wrap the blood pressure cuff snugly around your upper arm. The ...

  5. Blood pressure measurement

    MedlinePlus

    Diastolic blood pressure; Systolic blood pressure; Blood pressure reading; Measuring blood pressure ... your health care provider will wrap the blood pressure cuff snugly around your upper arm. The lower ...

  6. Blood Pressure Quiz

    MedlinePlus

    ... page please turn Javascript on. Feature: High Blood Pressure Blood Pressure Quiz Past Issues / Fall 2011 Table of Contents ... About High Blood Pressure / Treatment: Types of Blood Pressure Medications / Blood Pressure Quiz Fall 2011 Issue: Volume 6 Number ...

  7. Understanding Blood Pressure Readings

    MedlinePlus

    ... Pressure Tools & Resources Stroke More Understanding Blood Pressure Readings Updated:Aug 17,2016 Blood pressure is typically ... Your doctor should evaluate unusually low blood pressure readings. How is high blood pressure diagnosed? Your healthcare ...

  8. Organic electronics based pressure sensor towards intracranial pressure monitoring

    NASA Astrophysics Data System (ADS)

    Rai, Pratyush; Varadan, Vijay K.

    2010-04-01

    The intra-cranial space, which houses the brain, contains cerebrospinal fluid (CSF) that acts as a fluid suspension medium for the brain. The CSF is always in circulation, is secreted in the cranium and is drained out through ducts called epidural veins. The venous drainage system has inherent resistance to the flow. Pressure is developed inside the cranium, which is similar to a rigid compartment. Normally a pressure of 5-15 mm Hg, in excess of atmospheric pressure, is observed at different locations inside the cranium. Increase in Intra-Cranial Pressure (ICP) can be caused by change in CSF volume caused by cerebral tumors, meningitis, by edema of a head injury or diseases related to cerebral atrophy. Hence, efficient ways of monitoring ICP need to be developed. A sensor system and monitoring scheme has been discussed here. The system architecture consists of a membrane less piezoelectric pressure sensitive element, organic thin film transistor (OTFT) based signal transduction, and signal telemetry. The components were fabricated on flexible substrate and have been assembled using flip-chip packaging technology. Material science and fabrication processes, subjective to the device performance, have been discussed. Capability of the device in detecting pressure variation, within the ICP pressure range, is investigated and applicability of measurement scheme to medical conditions has been argued for. Also, applications of such a sensor-OTFT assembly for logic sensor switching and patient specific-secure monitoring system have been discussed.

  9. An inexpensive pressure transducer for the measurement of low amplitude unsteady pressure signals

    NASA Astrophysics Data System (ADS)

    Johnston, R. T.; Sullivan, J. P.

    1994-04-01

    Electret microphones were evaluated for use in an experiment to investigate the surface pressures of a wing immersed in a propeller slipstream. Calibration of a typical electret microphone over a range of 50 to 6000 hz showed that at each individual frequency there is less than 1.1% error in linearity for low pressures, but some variation of sensitivity occurs over the range of frequencies tested. This variation of sensitivity with frequency can be corrected using standard signal processing techniques.

  10. Teaching Medical Students About Observer Variation

    ERIC Educational Resources Information Center

    Koran, Lorrin M.; And Others

    1978-01-01

    To fully develop their diagnostic skills, medical students must recognize the limited reliability of the observations on which diagnoses are based. Study of 36 second-year students shows multiple sources of observer variation in readings of systolic and diastolic blood pressures. (LBH)

  11. Measurement of static pressure on aircraft

    NASA Technical Reports Server (NTRS)

    Gracey, William

    1958-01-01

    Existing data on the errors involved in the measurement of static pressure by means of static-pressure tubes and fuselage vents are presented. The errors associated with the various design features of static-pressure tubes are discussed for the condition of zero angle of attack and for the case where the tube is inclined to flow. Errors which result from variations in the configuration of static-pressure vents are also presented. Errors due to the position of a static-pressure tube in the flow field of the airplane are given for locations ahead of the fuselage nose, ahead of the wing tip, and ahead of the vertical tail fin. The errors of static-pressure vents on the fuselage of an airplane are also presented. Various methods of calibrating static-pressure installations in flight are briefly discussed.

  12. 49 CFR 195.406 - Maximum operating pressure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Maximum operating pressure. 195.406 Section 195... HAZARDOUS LIQUIDS BY PIPELINE Operation and Maintenance § 195.406 Maximum operating pressure. (a) Except for surge pressures and other variations from normal operations, no operator may operate a pipeline at...

  13. 49 CFR 195.406 - Maximum operating pressure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Maximum operating pressure. 195.406 Section 195... HAZARDOUS LIQUIDS BY PIPELINE Operation and Maintenance § 195.406 Maximum operating pressure. (a) Except for surge pressures and other variations from normal operations, no operator may operate a pipeline at...

  14. 49 CFR 195.406 - Maximum operating pressure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Maximum operating pressure. 195.406 Section 195... HAZARDOUS LIQUIDS BY PIPELINE Operation and Maintenance § 195.406 Maximum operating pressure. (a) Except for surge pressures and other variations from normal operations, no operator may operate a pipeline at...

  15. Increased intracranial pressure

    MedlinePlus

    Increased intracranial pressure is a rise in the pressure inside the skull that can result from or cause brain injury. ... Increased intracranial pressure can be due to a rise in pressure of the cerebrospinal fluid. This is ...

  16. Low Blood Pressure

    MedlinePlus

    ... High Blood Pressure Tools & Resources Stroke More Low Blood Pressure Updated:Aug 30,2016 To know if you ... to learn more about blood pressure . If my blood pressure stays around 85/55, do I have a ...

  17. Laser techniques in high-pressure geophysics

    NASA Technical Reports Server (NTRS)

    Hemley, R. J.; Bell, P. M.; Mao, H. K.

    1987-01-01

    Laser techniques in conjunction with the diamond-anvil cell can be used to study high-pressure properties of materials important to a wide range of problems in earth and planetary science. Spontaneous Raman scattering of crystalline and amorphous solids at high pressure demonstrates that dramatic changes in structure and bonding occur on compression. High-pressure Brillouin scattering is sensitive to the pressure variations of single-crystal elastic moduli and acoustic velocities. Laser heating techniques with the diamond-anvil cell can be used to study phase transitions, including melting, under deep-earth conditions. Finally, laser-induced ruby fluorescence has been essential for the development of techniques for generating the maximum pressures now possible with the diamond-anvil cell, and currently provides a calibrated in situ measure of pressure well above 100 gigapascals.

  18. Total pressure averaging in pulsating flows

    NASA Technical Reports Server (NTRS)

    Krause, L. N.; Dudzinski, T. J.; Johnson, R. C.

    1972-01-01

    A number of total-pressure tubes were tested in a non-steady flow generator in which the fraction of period that pressure is a maximum is approximately 0.8, thereby simulating turbomachine-type flow conditions. Most of the tubes indicated a pressure which was higher than the true average. Organ-pipe resonance which further increased the indicated pressure was encountered within the tubes at discrete frequencies. There was no obvious combination of tube diameter, length, and/or geometry variation used in the tests which resulted in negligible averaging error. A pneumatic-type probe was found to measure true average pressure, and is suggested as a comparison instrument to determine whether nonlinear averaging effects are serious in unknown pulsation profiles. The experiments were performed at a pressure level of 1 bar, for Mach number up to near 1, and frequencies up to 3 kHz.

  19. Jovimagnetic secular variation

    NASA Technical Reports Server (NTRS)

    Connerney, J. E. P.; Acuna, M. H.

    1982-01-01

    Long term variations of a planetary magnetic field are one of the few observables available in the study of planetary interiors and dynamo theory. While variations of the geomagnetic field were accessible to direct measurement for centuries, knowledge of the secular variations of other planetary dynamos is limited. New limits on Jovimagnetic secular variations were found by comparison of a Jovian internal field model obtained from the Voyager 1 magnetic field observations at epoch 1979.2 with the epoch 1974.9 Pioneer 11 O4 model. No significant secular variation of either the magnitude or position of the Jovidipole is found for the years 1974.9 through 1979.2, although a small Earth-like variation cannot be ruled out.

  20. An Investigation of Adaptive Pen Pressure Discretization Method Based on Personal Pen Pressure Use Profile

    NASA Astrophysics Data System (ADS)

    Xin, Yizhong; Ren, Xiangshi

    Continuous pen pressure can be used to operate multi-state widgets such as menus in pen based user interfaces. The number of levels into which the pen pressure space is divided determines the number of states in the multi-state widgets. To increase the optimal number of divisions of the pen pressure space and achieve greater pen pressure usability, we propose a new discretization method which divides the pen pressure space according to a personal pen pressure use profile. We present here four variations of the method: discretization according to personal/aggregation pen pressure use profile with/without visual feedback of uniform level widths and the traditional even discretization method. Two experiments were conducted respectively to investigate pen pressure use profile and to comparatively evaluate the performance of these methods. Results indicate that the subjects performed fastest and with the fewest errors when the pen pressure space was divided according to personal profile with visual feedback of uniform level widths (PU) and performed worst when the pen pressure space was divided evenly. With PU method, the optimal number of divisions of the pen pressure space was 8. Visual feedback of uniform level widths enhanced performance of uneven discretization. The findings of this study have implications for human-oriented pen pressure use in pen pressure based user interface designs.

  1. High-pressure inactivation of dried microorganisms.

    PubMed

    Espinasse, V; Perrier-Cornet, J-M; Marecat, A; Gervais, P

    2008-01-01

    Dried microorganisms are particularly resistant to high hydrostatic pressure effects. In this study, the survival of Saccharomyces cerevisiae was studied under pressure applied in different ways. Original processes and devices were purposely developed in our laboratory for long-term pressurization. Dried and wet yeast powders were submitted to high-pressure treatments (100-150 MPa for 24-144 h at 25 degrees C) through liquid media or inert gas. These powders were also pressurized after being vacuum-packed. In the case of wet yeasts, the pressurization procedure had little influence on the inactivation rate. In this case, inactivations were mainly due to hydrostatic pressure effects. Conversely, in the case of dried yeasts, inactivation was highly dependent on the treatment scheme. No mortality was observed when dried cells were pressurized in a non-aqueous liquid medium, but when nitrogen gas was used as the pressure-transmitting fluid, the inactivation rate was found to be between 1.5 and 2 log for the same pressure level and holding time. Several hypotheses were formulated to explain this phenomenon: the thermal effects induced by the pressure variations, the drying resulting from the gas pressure release and the sorption and desorption of the gas in cells. The highest inactivation rates were obtained with vacuum-packed dried yeasts. In this case, cell death occurred during the pressurization step and was induced by shear forces. Our results show that the mechanisms at the origin of cell death under pressure are strongly dependent on the nature of the pressure-transmitting medium and the hydration of microorganisms. PMID:17573691

  2. Subglottal pressure oscillations accompanying phonation.

    PubMed

    Sundberg, Johan; Scherer, Ronald; Hess, Markus; Müller, Frank; Granqvist, Svante

    2013-07-01

    Acoustic and aerodynamic properties of the voice source and vocal tract have been extensively analyzed during the last half century. Corresponding investigations of the subglottal system are rare but can be assumed to be relevant to voice production. In the present exploratory study, subglottal pressure was recorded in a male adult subject by means of tracheal puncture. Also recorded were the oral airflow and audio signals. Effects of vowel, phonation type, and vocal register shifts on the subglottal pressure waveform were examined. The moment of maximum flow declination rate was synchronous with the main positive peak of the subglottal pressure waveform. The three lowest subglottal resonance frequencies, determined by inverse filtering and long-term average spectra of the subglottal pressure during speech, were found to be about 500, 1220, and 2000Hz, irrespective of supraglottal variations and phonation type. However, the subglottal pressure waveform was affected by the supraglottal formants, whereas the radiated vowel spectra did not show clear influence by the subglottal resonances. The fundamental frequency immediately preceding and immediately following a register break in pitch glides did not show systematic relationships with formants or with the lowest subglottal resonance. PMID:23809566

  3. Sterilization of Fuji pressure-sensitive film.

    PubMed

    Liggins, A B; Hardie, W R; Finlay, J B

    1994-11-01

    Fuji Prescale film is a pressure-sensitive medium which produces a characteristic pink stain on the application of pressure. Up to a saturation level, increases in pressure will produce a denser stain, thereby providing a method of determining pressures within the interface between two articulating surfaces. The relationship between the magnitude of applied pressure and the optical density of the resulting stain is non-linear; this relationship also varies with ambient temperature and humidity, in addition to load rate, and therefore requires a calibration procedure prior to use. The use of Fuji prescale film for recording interface pressures within the joint space in vivo has been widely reported; however, the object of this study was to assess the effects of sterilizing this medium, with a view to future in vivo applications. Samples of Fuji film were sterilized using a standard ethylene oxide (ETO) gas process and their subsequent pressure-recording properties were compared to a control group of samples. The 'optical-density vs pressure' relationship for the sterilized group was significantly different from that of the control group (paired Student's t-test, P < = 0.001); however, both groups provided reliable data across the same pressure-range and both exhibited an excellent degree of repeatability (coefficient of variation < 2.5%). It was concluded that Fuji film will continue to produce pressure-stains following ETO sterilization; however, the calibration of this film will only be valid if it is conducted using film from the sterilized group. PMID:7858782

  4. Variations in Sexual Behavior.

    ERIC Educational Resources Information Center

    Juhasz, Anne McCreary

    1983-01-01

    Questions are raised about the difficulty of defining normal and atypical sexual behavior. Variations from normalcy that students, parents, and educators are most likely to encounter are discussed. The importance of dealing with variations in ways that are best for the individual and the group is emphasized. (PP)

  5. Barocaloric effect and the pressure induced solid state refrigerator

    SciTech Connect

    Oliveira, N. A. de

    2011-03-01

    The current refrigerators are based on the heating and cooling of fluids under external pressure variation. The great inconvenience of this refrigeration technology is the damage caused to the environment by the refrigerant fluids. In this paper, we discuss the magnetic barocaloric effect, i.e., the heating or cooling of magnetic materials under pressure variation and its application in the construction of refrigerators using solid magnetic compounds as refrigerant materials and pressure as the external agent. The discussion presented in this paper points out that such a pressure induced solid state refrigerator can be very interesting because it is not harmful to the environment and can exhibit a good performance.

  6. Dealing with Peer Pressure

    MedlinePlus

    ... Here's Help White House Lunch Recipes Dealing With Peer Pressure KidsHealth > For Kids > Dealing With Peer Pressure ... Let's talk about how to handle it. Defining Peer Pressure Peers influence your life, even if you ...

  7. Intracranial pressure monitoring

    MedlinePlus

    ... head. The monitor senses the pressure inside the skull and sends measurements to a recording device. ... are 3 ways to monitor pressure in the skull (intracranial pressure). INTRAVENTRICULAR CATHETER The intraventricular catheter is ...

  8. Skin (Pressure) Sores

    MedlinePlus

    ... Topic Skin dryness Next Topic Sleep problems Skin (pressure) sores A skin or pressure sore develops when the blood supply to an ... is bedridden or always in a wheelchair puts pressure on the same places much of the time. ...

  9. High blood pressure

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/000468.htm High blood pressure To use the sharing features on ... body. Hypertension is the term used to describe high blood pressure. Blood pressure readings are given as ...

  10. High blood pressure medicines

    MedlinePlus

    Hypertension - medicines ... blood vessel diseases. You may need to take medicines to lower your blood pressure if lifestyle changes ... blood pressure to the target level. WHEN ARE MEDICINES FOR HIGH BLOOD PRESSURE USED Most of the ...

  11. Intracranial pressure monitoring

    MedlinePlus

    ICP monitoring; CSF pressure monitoring ... There are 3 ways to monitor pressure in the skull (intracranial pressure). INTRAVENTRICULAR CATHETER The intraventricular catheter is the most accurate monitoring method. To insert an intraventricular catheter, a ...

  12. High blood pressure - infants

    MedlinePlus

    National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents. The fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescents. Pediatrics . ...

  13. High Blood Pressure (Hypertension)

    MedlinePlus

    ... Print Page Text Size: A A A Listen High Blood Pressure (Hypertension) Nearly 1 in 3 American adults has high ... weight. How Will I Know if I Have High Blood Pressure? High blood pressure is a silent problem — you ...

  14. High Blood Pressure

    MedlinePlus

    ... normal blood pressure 140/90 or higher is high blood pressure Between 120 and 139 for the top number, ... prehypertension. Prehypertension means you may end up with high blood pressure, unless you take steps to prevent it. High ...

  15. Preventing Pressure Sores

    MedlinePlus Videos and Cool Tools

    Experts \\ Preventing Pressure Sores Topics Adult Injuries Spinal Cord Injury 101 Spinal Cord Injury 101 The Basics of Spinal Cord Injury ... The Basics of Spinal Cord Injury Rehabilitation Preventing Pressure Sores Preventing Pressure Sores Transition from Hospital to ...

  16. Development of a dynamic pressure calibration technique

    NASA Technical Reports Server (NTRS)

    Vezzetti, C. F.; Hilten, J. S.; Lederer, P. S.

    1975-01-01

    The report deals with work continuing on the development of a method of producing sinusoidally varying pressures of at least 34 kPa zero-to-peak with amplitude variations within plus or minus 5% up to 2 kHz for the dynamic calibration of pressure transducers. Sinusoidally varying pressures of 34 kPa zero-to-peak were produced between 40 Hz and 750 Hz by vibrating a 10-cm column of a dimethyl siloxane liquid at 36gn zero-to-peak. Damping of the liquid column was accomplished by packing the fixture tube with a number of smaller diameter tubes.

  17. API connection modification to improve pressure integrity

    SciTech Connect

    Chelette, K.D.; Bollfrass, C.A.

    1983-01-01

    The pressure sealing integrity of API Round Thread and Buttress pipe connections is established by variations in the nominal design conditions that result from the specified dimensional tolerances. Several coupling modifications and procedures are presented herein to improve the sealing integrity of API connections. This improved coupling design uses multiple thread tapers to increase internal pressure ratings by insuring the location of the sealing point, insure tensile performance by excluding pressure from the thread region, and developing proper thread interference by controlling the final assembly position.

  18. Causes and significance of variation in mammalian basal metabolism.

    PubMed

    Raichlen, David A; Gordon, Adam D; Muchlinski, Magdalena N; Snodgrass, J Josh

    2010-02-01

    Mammalian basal metabolic rates (BMR) increase with body mass, whichs explains approximately 95% of the variation in BMR. However, at a given mass, there remains a large amount of variation in BMR. While many researchers suggest that the overall scaling of BMR with body mass is due to physiological constraints, variation at a given body mass may provide clues as to how selection acts on BMR. Here, we examine this variation in BMR in a broad sample of mammals and we test the hypothesis that, across mammals, body composition explains differences in BMR at a given body mass. Variation in BMR is strongly correlated with variation in muscle mass, and both of these variables are correlated with latitude and ambient temperature. These results suggest that selection alters BMR in response to thermoregulatory pressures, and that selection uses muscle mass as a means to generate this variation. PMID:19730868

  19. Total-pressure averaging in pulsating flows.

    NASA Technical Reports Server (NTRS)

    Krause, L. N.; Dudzinski, T. J.; Johnson, R. C.

    1972-01-01

    A number of total-pressure tubes were tested in a nonsteady flow generator in which the fraction of period that pressure is a maximum is approximately 0.8, thereby simulating turbomachine-type flow conditions. Most of the tubes indicated a pressure which was higher than the true average. Organ-pipe resonance which further increased the indicated pressure was encountered with the tubes at discrete frequencies. There was no obvious combination of tube diameter, length, and/or geometry variation used in the tests which resulted in negligible averaging error. A pneumatic-type probe was found to measure true average pressure and is suggested as a comparison instrument to determine whether nonlinear averaging effects are serious in unknown pulsation profiles.

  20. Periodic Heat Transfer at Small Pressure Fluctuations

    NASA Technical Reports Server (NTRS)

    Pfriem, H.

    1943-01-01

    The effect of cyclic gas pressure variations on the periodic heat transfer at a flat wall is theoretically analyzed and the differential equation describing the process and its solution for relatively. Small pressure fluctuations developed, thus explaining the periodic heat cycle between gas and wall surface. The processes for pure harmonic pressure and temperature oscillations, respectively, in the gas space are described by means of a constant heat transfer coefficient and the equally constant phase angle between the appearance of the maximum values of the pressure and heat flow most conveniently expressed mathematically in the form of a complex heat transfer coefficient. Any cyclic pressure oscillations, can be reduced by Fourier analysis to harmonic oscillations, which result in specific, mutual relationships of heat-transfer coefficients and phase angles for the different harmonics.

  1. Variable pressure ionization detector for gas chromatography

    DOEpatents

    Buchanan, Michelle V.; Wise, Marcus B.

    1988-01-01

    Method and apparatus for differentiating organic compounds based on their electron affinity. An electron capture detector cell (ECD) is operated at pressures ranging from atmospheric to less than 1 torr. Through variation of the pressure within the ECD cell, the organic compounds are induced to either capture or emit electrons. Differentiation of isomeric compounds can be obtianed when, at a given pressure, one isomer is in the emission mode and the other is in the capture mode. Output of the ECD is recorded by chromatogram. The invention also includes a method for obtaining the zero-crossing pressure of a compound, defined as the pressure at which the competing emission and capture reactions are balanced and which may be correlated to the electron affinity of a compound.

  2. Human variation databases

    PubMed Central

    Küntzer, Jan; Eggle, Daniela; Klostermann, Stefan; Burtscher, Helmut

    2010-01-01

    More than 100 000 human genetic variations have been described in various genes that are associated with a wide variety of diseases. Such data provides invaluable information for both clinical medicine and basic science. A number of locus-specific databases have been developed to exploit this huge amount of data. However, the scope, format and content of these databases differ strongly and as no standard for variation databases has yet been adopted, the way data is presented varies enormously. This review aims to give an overview of current resources for human variation data in public and commercial resources. PMID:20639550

  3. Thunderstorm related variations in stratospheric conductivity measurements

    NASA Technical Reports Server (NTRS)

    Hu, Hua; Holzworth, Robert H.; Li, Ya QI

    1989-01-01

    The vector electric field and polar conductivities were measured by zero-pressure balloon-borne payloads launched from Wallops Island, Virgina during the summers of 1987 and 1988. Data were collected over thunderstorms (or electrified clouds) during 6-hour flights at altitudes near 30 km. The vector electric field measurements were made with the double Langmuir probe high-impedance method, and the direct conductivity measurements were obtained with the relaxation technique. Evidence is presented for conductivity variations over thunderstorms (or electrified clouds). It is found that both positive and negative polar conductivity data do show variations of up to a factor of 2 from ambient values associated with the disturbed periods. Some ideas for possible physical mechanisms which may be responsible for the conductivity variations over thunderstorms are also discussed in this paper.

  4. The Schwinger Variational Method

    NASA Technical Reports Server (NTRS)

    Huo, Winifred M.

    1995-01-01

    Variational methods have proven invaluable in theoretical physics and chemistry, both for bound state problems and for the study of collision phenomena. For collisional problems they can be grouped into two types: those based on the Schroedinger equation and those based on the Lippmann-Schwinger equation. The application of the Schwinger variational (SV) method to e-molecule collisions and photoionization has been reviewed previously. The present chapter discusses the implementation of the SV method as applied to e-molecule collisions.

  5. Generalized quasi variational inequalities

    SciTech Connect

    Noor, M.A.

    1996-12-31

    In this paper, we establish the equivalence between the generalized quasi variational inequalities and the generalized implicit Wiener-Hopf equations using essentially the projection technique. This equivalence is used to suggest and analyze a number of new iterative algorithms for solving generalized quasi variational inequalities and the related complementarity problems. The convergence criteria is also considered. The results proved in this paper represent a significant improvement and refinement of the previously known results.

  6. Normal Pressure Hydrocephalus

    MedlinePlus

    ... Enhancing Diversity Find People About NINDS NINDS Normal Pressure Hydrocephalus Information Page Synonym(s): Hydrocephalus - Normal Pressure Table ... Español Additional resources from MedlinePlus What is Normal Pressure Hydrocephalus? Normal pressure hydrocephalus (NPH) is an abnormal ...

  7. Confusion about Pressure.

    ERIC Educational Resources Information Center

    Kuethe, Dean O.

    1991-01-01

    Listed are errors students make by accepting misconceptions about pressure and precautions teachers might take to avoid fostering those misconceptions. Misconceptions discussed include pressure as a measure of energy per unit volume, fluid flow only from high to low pressure, and the lack of pressures lower than a vacuum. (CW)

  8. High Blood Pressure

    MedlinePlus

    ... version of this page please turn Javascript on. High Blood Pressure What Is High Blood Pressure? High blood pressure is a common disease in ... the heart, kidneys, brain, and eyes. Types of High Blood Pressure There are two main types of high blood ...

  9. High Blood Pressure

    MedlinePlus

    ... page from the NHLBI on Twitter. Description of High Blood Pressure Español High blood pressure is a common disease ... defines high blood pressure severity levels. Stages of High Blood Pressure in Adults Stages Systolic (top number) Diastolic (bottom ...

  10. Chromatic variations suppress suprathreshold brightness variations.

    PubMed

    Kingdom, Frederick A A; Bell, Jason; Gheorghiu, Elena; Malkoc, Gokhan

    2010-01-01

    Most objects in natural scenes are suprathreshold in both color (chromatic) and luminance contrast. How salient is each dimension? We have developed a novel method employing a stimulus similar to that used by B. C. Regan and J. D. Mollon (1997) who studied the relative saliencies of the two chromatic cardinal directions. Our stimuli consist of left- and right-oblique modulations of color and/or luminance defined within a lattice of circles. In the "separated" condition, the two modulations were presented separately as forced-choice pairs, and the task was to indicate which was more salient. In the "combined" condition, the two orthogonal-in-orientation modulations were added, and the task was to indicate the more salient orientation. The ratio of color to luminance contrast at the PSE was calculated for both conditions. Across color directions, 48% more luminance contrast relative to color contrast was required to achieve a PSE in the "combined" compared to the "separated" condition. A second experiment showed that the PSE difference was due to the luminance being masked by the color, rather than due to superior color grouping. We conclude that suprathreshold brightness variations are masked by suprathreshold color variations. PMID:20884478

  11. Variation in Atmospheric Helium Isotopes

    NASA Astrophysics Data System (ADS)

    Mabry, J. C.; Marty, B.; Burnard, P.; Blard, P.

    2010-12-01

    Anthropogenic activity such as oil and gas exploitation releases crustal helium, which has excess 4He compared to atmospheric helium. This may give rise to both spatial and temporal variations in the atmospheric 3He/4He. Helium is present in trace quantities in the air (5 ppm) and has a very low ratio (3He/4Heair = 1.38 x 10-6), consequently high precision measurements of atmospheric He presents a significant analytical challenge. Recent work by Sano et al. [1] has endeavored to experimentally quantify these potential variations in the atmospheric 3He/4He by measuring the helium isotopes from air samples collected around the globe and from samples of ancient trapped atmosphere. Their results indicate an increase in the atmospheric 3He/4He from northern to southern latitudes of the order 2 - 4 ‰, which they attribute to greater use of fossil fuels in the northern hemisphere. However, since most of their data points overlap at the 2-3 ‰ (2σ) level, additional measurements (with increased precision if possible) are needed. We have constructed an automated extraction line dedicated to measuring He in samples of air which can rapidly switch between measuring aliquots of sample with standards. It additionally features an adjustable bellows on the sample aliquot volume that enables us to adjust the size of a sample aliquot to precisely match the standard, eliminating biases arising from nonlinear pressure effects in the mass spectrometer. The measurements are made using a Helix SFT multi-collector mass spectrometer. At present, repeat measurements of 3He/4He from our standard (purified air) have a reproducibility of 2‰ (2σ), while measurements of local (Nancy, France) air samples have a reproducibility of 3He/4He of 3‰ (2σ), which are at a similar level to the uncertainties reported by Sano. Modifications are underway to improve 3He measurements which are the principal source of error. We have collected atmospheric samples from around the globe over a wide

  12. Pressure Dome for High-Pressure Electrolyzer

    NASA Technical Reports Server (NTRS)

    Norman, Timothy; Schmitt, Edwin

    2012-01-01

    A high-strength, low-weight pressure vessel dome was designed specifically to house a high-pressure [2,000 psi (approx. = 13.8 MPa)] electrolyzer. In operation, the dome is filled with an inert gas pressurized to roughly 100 psi (approx. = 690 kPa) above the high, balanced pressure product oxygen and hydrogen gas streams. The inert gas acts to reduce the clamping load on electrolyzer stack tie bolts since the dome pressure acting axially inward helps offset the outward axial forces from the stack gas pressure. Likewise, radial and circumferential stresses on electrolyzer frames are minimized. Because the dome is operated at a higher pressure than the electrolyzer product gas, any external electrolyzer leak prevents oxygen or hydrogen from leaking into the dome. Instead the affected stack gas stream pressure rises detectably, thereby enabling a system shutdown. All electrical and fluid connections to the stack are made inside the pressure dome and require special plumbing and electrical dome interfaces for this to be accomplished. Further benefits of the dome are that it can act as a containment shield in the unlikely event of a catastrophic failure. Studies indicate that, for a given active area (and hence, cell ID), frame outside diameter must become ever larger to support stresses at higher operating pressures. This can lead to a large footprint and increased costs associated with thicker and/or larger diameter end-plates, tie-rods, and the frames themselves. One solution is to employ rings that fit snugly around the frame. This complicates stack assembly and is sometimes difficult to achieve in practice, as its success is strongly dependent on frame and ring tolerances, gas pressure, and operating temperature. A pressure dome permits an otherwise low-pressure stack to operate at higher pressures without growing the electrolyzer hardware. The pressure dome consists of two machined segments. An O-ring is placed in an O-ring groove in the flange of the bottom

  13. Electrical power generation from salinity gradients using pressure retarded osmosis

    SciTech Connect

    Emery, A.F.; Yourstone, W.H.

    1983-08-01

    The use of a pressure retarded osmosis system (PRO) to generate electricity form naturally available or artificially generated salt is described. Variations in overall system efficiency are analyzed in terms of freshwater and brine flow rates, fluid pressure levels, and membrane permeability. It is shown that the PRO system is economically competitive with other alternative energy systems.

  14. Electrical power generation from salinity gradients using pressure retarded osmosis

    NASA Astrophysics Data System (ADS)

    Emery, A. F.; Yourstone, W. H., Jr.

    The use of a pressure retarded osmosis system (PRO) to generate electricity from naturally available or artificially generated salt is described. Variations in overall system efficiency are analyzed in terms of freshwater and brine flow rates, fluid pressure levels, and membrane permeability. It is shown that the PRO system is economically competitive with other alternative energy systems.

  15. Pressure sensitivity of low permeability sandstones

    USGS Publications Warehouse

    Kilmer, N.H.; Morrow, N.R.; Pitman, J.K.

    1987-01-01

    Detailed core analysis has been carried out on 32 tight sandstones with permeabilities ranging over four orders of magnitude (0.0002 to 4.8 mD at 5000 psi confining pressure). Relationships between gas permeability and net confining pressure were measured for cycles of loading and unloading. For some samples, permeabilities were measured both along and across bedding planes. Large variations in stress sensitivity of permeability were observed from one sample to another. The ratio of permeability at a nominal confining pressure of 500 psi to that at 5000 psi was used to define a stress sensitivity ratio. For a given sample, confining pressure vs permeability followed a linear log-log relationship, the slope of which provided an index of pressure sensitivity. This index, as obtained for first unloading data, was used in testing relationships between stress sensitivity and other measured rock properties. Pressure sensitivity tended to increase with increase in carbonate content and depth, and with decrease in porosity, permeability and sodium feldspar. However, scatter in these relationships increased as permeability decreased. Tests for correlations between pressure sensitivity and various linear combinations of variables are reported. Details of pore structure related to diagenetic changes appears to be of much greater significance to pressure sensitivity than mineral composition. ?? 1987.

  16. Variations in genome mass.

    PubMed

    Wachtel, S S; Tiersch, T R

    1993-02-01

    1. Genome size varies considerably among vertebrates, ranging from less than 1 pg to more than 200 pg; the amount of DNA differing among individuals in a population can equal the amount in the entire structural gene complement. 2. Recent technological advances permit evaluation of genome size variation at several levels including sub-chromosomal, chromosomal and cellular. 3. Genome size variation may also be viewed from taxonomic levels, and across evolutionary time frames. 4. As sources of genome size variation are identified and studied, the conundrum of the C-value paradox (lack of correlations among genome size, genomic complexity and phylogenetic status of organisms) may prove to be more apparent than real. 5. For example, the limited and relatively constant genome size of avians may be related to the physiological constraints of flight. PMID:8462275

  17. Essential Variational Poisson Cohomology

    NASA Astrophysics Data System (ADS)

    De Sole, Alberto; Kac, Victor G.

    2012-08-01

    In our recent paper "The variational Poisson cohomology" (2011) we computed the dimension of the variational Poisson cohomology {{{H}^bullet_K({V})}} for any quasiconstant coefficient ℓ × ℓ matrix differential operator K of order N with invertible leading coefficient, provided that {{{V}}} is a normal algebra of differential functions over a linearly closed differential field. In the present paper we show that, for K skewadjoint, the {{{Z}}} -graded Lie superalgebra {{{H}^bullet_K({V})}} is isomorphic to the finite dimensional Lie superalgebra {{widetilde{H}(Nell,S)}} . We also prove that the subalgebra of "essential" variational Poisson cohomology, consisting of classes vanishing on the Casimirs of K, is zero. This vanishing result has applications to the theory of bi-Hamiltonian structures and their deformations. At the end of the paper we consider also the translation invariant case.

  18. Mediterranean sea level variations.

    NASA Astrophysics Data System (ADS)

    Vigo, I.; Sánchez Reales, J. M.; García, D.; Chao, B. F.

    2009-04-01

    In this work we report an updated study of the sea level variations for the Mediterranean sea for the period from October 1992 to January 2008. The study addresses two mayor issues: (i)The analysis of the spatial and temporal variability of sea surface height (SSH) from radar altimetry measurements (from TOPEX/Poseidon (T/P) + Jason-1, etc.). We use EOF analysis to explain most of its interannual variation, and how the different basins interact. (ii) The analysis of dynamics and balance of water mass transport for the whole period. We estimate the steric SSH by combining the steric SSH estimated from temperature and salt profiles simulated by the ECCO model with time-variable gravity (TVG) data (from GRACE) for the Mediterranean Sea. The estimated steric SSH together with the SSH obtained from altimetry allow for a more realistic estimation of the water mass variations in the Mediterranean for the whole period.

  19. Comparison of FBG responses to static and dynamic pressures

    NASA Astrophysics Data System (ADS)

    Shafir, E.; Zilberman, S.; Ravid, A.; Glam, B.; Appelbaum, G.; Fedotov Gefen, A.; Saadi, Y.; Shafir, N.; Berkovic, G.

    2014-05-01

    FBGs respond to external pressures in ways that reflect both the strain-optic effect and the geometrical variations, both induced by the applied pressure. While the response to static isotropic pressure is quite straight forward and intuitive, the response to anisotropic shock waves is much more complex and depends also on the relative orientation between the fiber and the shock propagation direction. We describe and explain experimental results for both cases.

  20. Effective anisotropy gradient in pressure graded [Co/Pd] multilayers

    SciTech Connect

    Kirby, B. J. Maranville, B. B.; Greene, P. K.; Liu, Kai; Davies, J. E.

    2015-02-14

    We have used polarized neutron reflectometry to show that controlled variation of growth pressure during deposition of Co/Pd multilayers can be used to achieve a significant vertical gradient in the effective anisotropy. This gradient is strongly dependent on deposition order (low to high pressure or vice versa), and is accompanied by a corresponding gradient in saturation magnetization. These results demonstrate pressure-grading as an attractively simple technique for tailoring the anisotropy profile of magnetic media.

  1. Experimental study of three exit pressure distortions on turbine performance

    NASA Astrophysics Data System (ADS)

    Gaddis, Stephen W.; Boynton, James L.

    1993-06-01

    A cold flow air test of the Space Shuttle Main Engine (SSME) High Pressure Fuel Turbopump (HPFTP) turbine was conducted with a circumferential pressure distortion at the turbine exit. The effects of three circumferential exit pressure distortions on turbine efficiency and pressure ratio, are presented. Circumferential and radial total pressure, total temperature, static pressure, and flow angle distributions at the turbine exit are also presented. Efficiency and total-to-total pressure ratio are shown to have a circumferential variation as high as 13.7 percent (or points of efficiency) and 7.1 percent, respectively. A slight pressure distortion was measured downstream of the first stage nozzle and the distortion increased across subsequent blade rows to a maximum downstream of the second stage rotor for all three plates. A brief discussion of the test facility, model, instrumentation, and test plan is given for completeness.

  2. High Blood Pressure in Pregnancy

    MedlinePlus

    ... The Health Information Center High Blood Pressure in Pregnancy What Is High Blood Pressure? Blood pressure is ... Are the Effects of High Blood Pressure in Pregnancy? Although many pregnant women with high blood pressure ...

  3. Lipid decorated liquid crystal pressure sensors

    NASA Astrophysics Data System (ADS)

    Lopatkina, Tetiana; Popov, Piotr; Honaker, Lawrence; Jakli, Antal; Mann, Elizabeth; Mann's group Collaboration; Jakli's group Collaboration

    Surfactants usually promote the alignment of liquid crystal (LC) director parallel to the surfactant chains, and thus on average normal to the substrate (homeotropic), whereas water promotes tangential (planar) alignment. A water-LC interface is therefore very sensitive to the presence of surfactants, such as lipids: this is the principle of LC-based chemical and biological sensing introduced by Abbott et al.Using a modified configuration, we found that at higher than 10 micro molar lipid concentration, the uniformly dark texture seen for homeotropic alignment between left-, and right-handed circular polarizers becomes unstable and slowly brightens again. This texture shows extreme sensitivity to external air pressure variations offering its use for sensitive pressure sensors. Our analysis indicates an osmotic pressure induced bending of the suspended films explaining both the birefringence and pressure sensitivity. In the talk we will discuss the experimental details of these effects. This work was financially supported by NSF DMR No. DMR-0907055.

  4. Pressure sensing by flexible, organic, field effect transistors

    NASA Astrophysics Data System (ADS)

    Manunza, I.; Sulis, A.; Bonfiglio, A.

    2006-10-01

    A mechanical sensor based on a pentacene field effect transistor has been fabricated. The pressure dependence of the output current has been investigated by applying a mechanical stimulus by means of a pressurized air flow. Experimental results show a reversible current dependence on pressure. Data analysis suggests that variations of threshold voltage, mobility and contact resistance are responsible for current variations. Thanks to the flexibility of the substrate and the low cost of the technology, this device opens the way for flexible mechanical sensors that can be used in a variety of innovative applications such as e-textiles and robotic interfaces.

  5. Atmospheric Pressure Indicator.

    ERIC Educational Resources Information Center

    Salzsieder, John C.

    1995-01-01

    Discusses observable phenomena related to air pressure. Describes a simple, unobtrusive, semiquantitative device to monitor the changes in air pressure that are associated with altitude, using a soft-drink bottle and a balloon. (JRH)

  6. Pressure surge attenuator

    DOEpatents

    Christie, Alan M.; Snyder, Kurt I.

    1985-01-01

    A pressure surge attenuation system for pipes having a fluted region opposite crushable metal foam. As adapted for nuclear reactor vessels and heads, crushable metal foam is disposed to attenuate pressure surges.

  7. Blood Pressure Medicines

    MedlinePlus

    ... reducing sodium in your diet, you may need medicines. Blood pressure medicines work in different ways to lower blood pressure. ... and widen blood vessels. Often, two or more medicines work better than one. NIH: National Heart, Lung, ...

  8. Low blood pressure

    MedlinePlus

    Hypotension; Blood pressure - low; Postprandial hypotension; Orthostatic hypotension; Neurally mediated hypotension; NMH ... Blood pressure varies from one person to another. A drop as little as 20 mmHg, can cause ...

  9. The Root Pressure Phenomenon

    ERIC Educational Resources Information Center

    Marsh, A. R.

    1972-01-01

    Describes experiments demonstrating that root pressure in plants is probably controlled by a circadian rhythm (biological clock). Root pressure phenomenon plays significant part in water transport in contradiction with prevalent belief. (PS)

  10. Flange weld pressure testing

    NASA Technical Reports Server (NTRS)

    Holden, C. F.

    1977-01-01

    Device allows localized high-pressure proof test. Use of tool eliminates need to block off far end of pipe; only small amount of pressurizing gas is needed; only small area needs to be cleared of personnel for proof test.

  11. Pressure Sensitive Paints

    NASA Technical Reports Server (NTRS)

    Liu, Tianshu; Bencic, T.; Sullivan, J. P.

    1999-01-01

    This article reviews new advances and applications of pressure sensitive paints in aerodynamic testing. Emphasis is placed on important technical aspects of pressure sensitive paint including instrumentation, data processing, and uncertainty analysis.

  12. Low blood pressure

    MedlinePlus

    Hypotension; Blood pressure - low; Postprandial hypotension; Orthostatic hypotension; Neurally mediated hypotension; NMH ... Blood pressure varies from one person to another. A drop as little as 20 mmHg, can cause problems for ...

  13. Blood Pressure Medicines

    MedlinePlus

    High blood pressure, also called hypertension, usually has no symptoms. But it can cause serious problems such as stroke, heart failure, ... failure. If you cannot control your high blood pressure through lifestyle changes such as losing weight and ...

  14. Hypertension (High Blood Pressure)

    MedlinePlus

    ... pressure to live. Without it, blood can't flow through our bodies and carry oxygen to our vital organs. But when blood pressure gets too high — a condition called hypertension — it can lead to ...

  15. Hypertension (High Blood Pressure)

    MedlinePlus

    ... blood pressure with the development of a practical method to measure it. Physicians began to note associations between hypertension and risk of heart failure, stroke, and kidney failure. Although scientists had yet to prove that lowering blood pressure ...

  16. High blood pressure - infants

    MedlinePlus

    Hypertension - infants ... and blood vessels The health of the kidneys High blood pressure in infants may be due to kidney or ... Bronchopulmonary dysplasia Renal artery stenosis In newborn babies, high blood pressure is often caused by a blood clot in ...

  17. Variation and Linguistic Theory.

    ERIC Educational Resources Information Center

    Bailey, Charles-James N.

    This volume presents principles and models for describing language variation, and introduces a time-based, dynamic framework for linguistic description. The book first summarizes some of the problems of grammatical description encountered from Saussure through the present and then outlines possibilities for new descriptions of language which take…

  18. Seasonal Variation in Epidemiology

    ERIC Educational Resources Information Center

    Marrero, Osvaldo

    2013-01-01

    Seasonality analyses are important in medical research. If the incidence of a disease shows a seasonal pattern, then an environmental factor must be considered in its etiology. We discuss a method for the simultaneous analysis of seasonal variation in multiple groups. The nuts and bolts are explained using simple trigonometry, an elementary…

  19. Variational transition state theory

    SciTech Connect

    Truhlar, D.G.

    1993-12-01

    This research program involves the development of variational transition state theory (VTST) and semiclassical tunneling methods for the calculation of gas-phase reaction rates and selected applications. The applications are selected for their fundamental interest and/or their relevance to combustion.

  20. (Genomic variation in maize)

    SciTech Connect

    Rivin, C.J.

    1991-01-01

    These studies have sought to learn how different DNA sequences and sequence arrangements contribute to genome plasticity in maize. We describe quantitative variation among maize inbred lines for tandemly arrayed and dispersed repeated DNA sequences and gene families, and qualitative variation for sequences homologous to the Mutator family of transposons. The potential of these sequences to undergo unequal crossing over, non-allelic (ectopic) recombination and transposition makes them a source of genome instability. We have found examples of rapid genomic change involving these sequences in Fl hybrids, tissue culture cells and regenerated plants. We describe the repetitive portion of the maize genome as composed primarily of sequences that vary markedly in copy number among different genetic stocks. The most highly variable is the 185 bp repeat associated with the heterochromatic chromosome knobs. Even in lines without visible knobs, there is a considerable quantity of tandemly arrayed repeats. We also found a high degree of variability for the tandemly arrayed 5S and ribosomal DNA repeats. While such variation might be expected as the result of unequal cross-over, we were surprised to find considerable variation among lower copy number, dispersed repeats as well. One highly repeated sequence that showed a complex tandem and dispersed arrangement stood out as showing no detectable variability among the maize lines. In striking contrast to the variability seen between the inbred stocks, individuals within a stock were indistinguishable with regard to their repeated sequence multiplicities.

  1. Sociolinguistic Variation and Change.

    ERIC Educational Resources Information Center

    Trudgill, Peter

    This book examines linguistic variation and change. Section 1, "Sociohistorical Linguistics," includes: (1) "British Vernacular Dialects in the Formation of American English: The Case of East Anglian 'Do'"; (2) "'Short o' in East Anglia and New England"; and (3) "Sociohistorical Linguistics and Dialect Survival: A Note on Another Nova Scotian…

  2. Determining Faculty Grading Variation.

    ERIC Educational Resources Information Center

    Demerjian, Marlene D.

    A study was undertaken at the College of the Canyons, in California, to assess the variation of grades given by mathematics instructors teaching intermediate algebra. A sample was drawn from all instructors who taught Math 070 repeatedly from fall 1990 to fall 1994, resulting in the examination of the grades of at least 200 students from classes…

  3. Fluency Variation in Adolescents

    ERIC Educational Resources Information Center

    De Andrade, Claudia Regina Furquim; Martins, Vanessa De Oliveira

    2007-01-01

    The Speech Fluency Profile of fluent adolescent speakers of Brazilian Portuguese, were examined with respect to gender and neurolinguistic variations. Speech samples of 130 male and female adolescents, aged between 12;0 and 17;11 years were gathered. They were analysed according to type of speech disruption; speech rate; and frequency of speech…

  4. Cruise aerodynamics of USB nacelle/wing geometric variations

    NASA Technical Reports Server (NTRS)

    Braden, J. A.; Hancock, J. P.; Burdges, K. P.

    1976-01-01

    Experimental results are presented on aerodynamic effects of geometric variations in upper surface blown nacelle configurations at high speed cruise conditions. Test data include both force and pressure measurements on two and three dimensional models powered by upper surface blowing nacelles of varying geometries. Experimental results are provided on variations in nozzle aspect ratio, nozzle boattail angle, and multiple nacelle installations. The nacelles are ranked according to aerodynamic drag penalties as well as overall installed drag penalties. Sample effects and correlations are shown for data obtained with the pressure model.

  5. Pressure-sensitive optrode

    DOEpatents

    Hirschfeld, T.B.

    1986-07-15

    An apparatus is provided for sensing changes in pressure and for generating optical signals related to said changes in pressure. Light from a fiber optic illuminates a fluorescent composition causing it to fluoresce. The fluorescent composition is caused to fluoresce more relative to the end of the fiber optic in response to changes in pressure so that the intensity of fluorescent emissions collected by the same fiber optic used for illumination varies monotonically with pressure. 10 figs.

  6. Pressure-sensitive optrode

    DOEpatents

    Hirschfeld, Tomas B.

    1986-01-01

    An apparatus is provided for sensing changes in pressure and for generating optical signals related to said changes in pressure. Light from a fiber optic illuminates a fluorescent composition causing it to fluoresce. The fluorescent composition is caused to more relative to the end of the fiber optic in response to changes in pressure so that the intensity of fluorescent emissions collected by the same fiber optic used for illumination varies monotonically with pressure.

  7. Relative microvascular pressure sensing

    NASA Astrophysics Data System (ADS)

    Choi, Min; Zemp, Roger

    2016-03-01

    Microcirculation may be characterized by the vascular pressure as it is influenced by pressure-driven perfusion. Crosssections of blood vessels can be visualized by photoacoustic imaging and compressing on vessels causes deformation. The photoacoustic signals of blood, when compressed to the point of vessel collapse, may or may not vanish depending on the buckling process it undergoes. We form relative pressure images of microvessels by tracking vessel collapse as a function of externally applied pressure using photoacoustic imaging.

  8. Tunable high pressure lasers

    NASA Technical Reports Server (NTRS)

    Hess, R. V.

    1976-01-01

    Atmospheric transmission of high energy CO2 lasers is considerably improved by high pressure operation which, due to pressure broadening, permits tuning the laser lines off atmospheric absorption lines. Pronounced improvement is shown for horizontal transmission at altitudes above several kilometers and for vertical transmission through the entire atmosphere. Applications of tunable high pressure CO2 lasers to energy transmission and to remote sensing are discussed along with initial efforts in tuning high pressure CO2 lasers.

  9. Glottal Adduction and Subglottal Pressure in Singing.

    PubMed

    Herbst, Christian T; Hess, Markus; Müller, Frank; Švec, Jan G; Sundberg, Johan

    2015-07-01

    Previous research suggests that independent variation of vocal loudness and glottal configuration (type and degree of vocal fold adduction) does not occur in untrained speech production. This study investigated whether these factors can be varied independently in trained singing and how subglottal pressure is related to average glottal airflow, voice source properties, and sound level under these conditions. A classically trained baritone produced sustained phonations on the endoscopic vowel [i:] at pitch D4 (approximately 294 Hz), exclusively varying either (a) vocal register; (b) phonation type (from "breathy" to "pressed" via cartilaginous adduction); or (c) vocal loudness, while keeping the others constant. Phonation was documented by simultaneous recording of videokymographic, electroglottographic, airflow and voice source data, and by percutaneous measurement of relative subglottal pressure. Register shifts were clearly marked in the electroglottographic wavegram display. Compared with chest register, falsetto was produced with greater pulse amplitude of the glottal flow, H1-H2, mean airflow, and with lower maximum flow declination rate (MFDR), subglottal pressure, and sound pressure. Shifts of phonation type (breathy/flow/neutral/pressed) induced comparable systematic changes. Increase of vocal loudness resulted in increased subglottal pressure, average flow, sound pressure, MFDR, glottal flow pulse amplitude, and H1-H2. When changing either vocal register or phonation type, subglottal pressure and mean airflow showed an inverse relationship, that is, variation of glottal flow resistance. The direct relation between subglottal pressure and airflow when varying only vocal loudness demonstrated independent control of vocal loudness and glottal configuration. Achieving such independent control of phonatory control parameters would be an important target in vocal pedagogy and in voice therapy. PMID:25944295

  10. Diurnal variations of Titan

    NASA Astrophysics Data System (ADS)

    Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Mueller-Wodarg, I. C. F.; Kasprzak, W. T.; Waite, J. H.

    2009-04-01

    We present our analysis of the diurnal variations of Titan's ionosphere (between 1,000 and 1,400 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from 8 close encounters of the Cassini spacecraft with Titan. Though there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ~700 cm-3 below ~1,300 km. Such a plateau is associated with the combination of distinct diurnal variations of light and heavy ions. Light ions (e.g. CH5+, HCNH+, C2H5+) show strong diurnal variation, with clear bite-outs in their nightside distributions. In contrast, heavy ions (e.g. c-C3H3+, C2H3CNH+, C6H7+) present modest diurnal variation, with significant densities observed on the nightside. We propose that the distinctions between light and heavy ions are associated with their different chemical loss pathways, with the former primarily through "fast" ion-neutral chemistry and the latter through "slow" electron dissociative recombination. The INMS data suggest day-to-night transport as an important source of ions on Titan's nightside, to be distinguished from the conventional scenario of auroral ionization by magnetospheric particles as the only ionizing source on the nightside. This is supported by the strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes. We construct a time-dependent ion chemistry model to investigate the effects of day-to-night transport on the ionospheric structures of Titan. The predicted diurnal variation has similar general characteristics to those observed, with some apparent discrepancies which could be reconciled by imposing fast horizontal thermal winds in Titan's upper atmosphere.

  11. High Blood Pressure (Hypertension)

    MedlinePlus

    ... For Consumers Consumer Information by Audience For Women High Blood Pressure (Hypertension) Share Tweet Linkedin Pin it More sharing options ... En Español Who is at risk? How is high blood pressure treated? Understanding your blood pressure: What do the ...

  12. Inertia diaphragm pressure transducer

    NASA Technical Reports Server (NTRS)

    Seegmiller, H. L. B.

    1971-01-01

    Transducer measures gas pressure profiles in high temperature, short duration, gas flows usually found in devices where pressure pulses may have durations of few microseconds to several milliseconds. Assembly includes fluid delay line, delay chamber, and flow restrictor for equalizing steady state pressure on diaphragm's sides

  13. Brain Pressure Monitoring

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A transducer originally used to measure air pressure in aircraft wind tunnel tests is the basis for a development important in diagnosis and treatment of certain types of brain damage. A totally implantable device, tbe intracranial pressure monitor measures and reports brain pressure by telemetry.

  14. Pressure Relief Devices

    NASA Astrophysics Data System (ADS)

    Manha, William D.

    2010-09-01

    Pressure relief devices are used in pressure systems and on pressure vessels to prevent catastrophic rupture or explosion from excessive pressure. Pressure systems and pressure vessels have manufacturers maximum rated operating pressures or maximum design pressures(MDP) for which there are relatively high safety factors and minimum risk of rupture or explosion. Pressure systems and pressure vessels that have a potential to exceed the MDP by being connected to another higher pressure source, a compressor, or heat to water(boiler) are required to have over-pressure protecting devices. Such devices can be relief valves and/or burst discs to safely relieve potentially excessive pressure and prevent unacceptable ruptures and explosions which result in fail-safe pressure systems and pressure vessels. Common aerospace relief valve and burst disc requirements and standards will be presented. This will include the NASA PSRP Interpretation Letter TA-88-074 Fault Tolerance of Systems Using Specially Certified Burst Disks that dictates burst disc requirements for payloads on Shuttle. Two recent undesirable manned space payloads pressure relief devices and practices will be discussed, as well as why these practices should not be continued. One example for discussion is the use of three burst discs that have been placed in series to comply with safety requirements of three controls to prevent a catastrophic hazard of the over-pressurization and rupture of pressure system and/or vessels. The cavities between the burst discs are evacuated and are the reference pressures for activating the two upstream burst discs. If the upstream burst disc leaks into the reference cavity, the reference pressure increases and it can increase the burst disc activating pressure and potentially result in the burst disc assembly being ineffective for over pressure protection. The three burst discs-in-series assembly was found acceptable because the burst discs are designed for minimum risk(DFMR) of

  15. Fracture analysis of axially cracked pressure tube of pressurized heavy water reactor

    SciTech Connect

    Krishnan, S.; Bhasin, V.; Mahajan, S.C.

    1997-04-01

    Three Dimensional (313) finite element elastic plastic fracture analysis was done for through wall axially cracked thin pressure tubes of 220 MWe Indian Pressurized Heavy Water Reactor. The analysis was done for Zr-2 and Zr-2.5Nb pressure tubes operating at 300{degrees}C and subjected to 9.5 Mpa internal pressure. Critical crack length was determined based on tearing instability concept. The analysis included the effect of crack face pressure due to the leaking fluid from tube. This effect was found to be significant for pressure tubes. The available formulae for calculating J (for axially cracked tubes) do not take into account the effect of crack face pressure. 3D finite element analysis also gives insight into variation of J across the thickness of pressure tube. It was observed that J is highest at the mid-surface of tube. The results have been presented in the form of across the thickness average J value and a peak factor on J. Peak factor on J is ratio of J at mid surface to average J value. Crack opening area for different cracked lengths was calculated from finite element results. The fracture assessment of pressure tubes was also done using Central Electricity Generating Board R-6 method. Ductile tearing was considered.

  16. Combustion pressure sensor arrangement

    SciTech Connect

    Sawamoto, K.; Nagaishi, H.; Takeuchi, K.

    1986-07-29

    A combustion pressure sensor arrangement in an internal combustion engine having a cylinder head, comprising: a plug seating formed in the cylinder head; an annular pressure sensor; an ignition plug screwed into the cylinder head in such a manner that the pressure sensor is clamped between the ignition plug and the plug seating; an ignition plug accommodation hole formed in the cylinder head for accommodating therein the ignition plug; and a guide sleeve joined at one end thereof to the outer periphery of the pressure sensor and fitted in the ignition plug accommodation hole, wherein the one end of the guide sleeve is fitted on the outer periphery of the pressure sensor.

  17. Dynamic Pressure Difference Microphones

    NASA Astrophysics Data System (ADS)

    Werner, E.

    A microphone with a diaphragm that is exposed to the sound field only on one side responds essentially to the sound pressure. This quantity is a scalar, and thus, pressure microphones are essentially omnidirectional (see Chapter 66). However, directional microphones are useful because they make it possible to focus on a source and suppress background noise from other directions. Most directional microphones respond to the gradient of the sound pressure, to combinations of the sound pressure and its gradient, or to combinations of higher order spatial derivatives of the sound pressure.

  18. Toward an internally consistent pressure scale

    PubMed Central

    Fei, Yingwei; Ricolleau, Angele; Frank, Mark; Mibe, Kenji; Shen, Guoyin; Prakapenka, Vitali

    2007-01-01

    Our ability to interpret seismic observations including the seismic discontinuities and the density and velocity profiles in the earth's interior is critically dependent on the accuracy of pressure measurements up to 364 GPa at high temperature. Pressure scales based on the reduced shock-wave equations of state alone may predict pressure variations up to 7% in the megabar pressure range at room temperature and even higher percentage at high temperature, leading to large uncertainties in understanding the nature of the seismic discontinuities and chemical composition of the earth's interior. Here, we report compression data of gold (Au), platinum (Pt), the NaCl-B2 phase, and solid neon (Ne) at 300 K and high temperatures up to megabar pressures. Combined with existing experimental data, the compression data were used to establish internally consistent thermal equations of state of Au, Pt, NaCl-B2, and solid Ne. The internally consistent pressure scales provide a tractable, accurate baseline for comparing high pressure–temperature experimental data with theoretical calculations and the seismic observations, thereby advancing our understanding fundamental high-pressure phenomena and the chemistry and physics of the earth's interior. PMID:17483460

  19. High pressure water jet cutting and stripping

    NASA Technical Reports Server (NTRS)

    Hoppe, David T.; Babai, Majid K.

    1991-01-01

    High pressure water cutting techniques have a wide range of applications to the American space effort. Hydroblasting techniques are commonly used during the refurbishment of the reusable solid rocket motors. The process can be controlled to strip a thermal protective ablator without incurring any damage to the painted surface underneath by using a variation of possible parameters. Hydroblasting is a technique which is easily automated. Automation removes personnel from the hostile environment of the high pressure water. Computer controlled robots can perform the same task in a fraction of the time that would be required by manual operation.

  20. DEVICE FOR CONTROL OF OXYGEN PARTIAL PRESSURE

    DOEpatents

    Bradner, H.; Gordon, H.S.

    1957-12-24

    A device is described that can sense changes in oxygen partial pressure and cause a corresponding mechanical displacement sufficient to actuate meters, valves and similar devices. A piston and cylinder arrangement contains a charge of crystalline metal chelate pellets which have the peculiar property of responding to variations in the oxygen content of the ambient atmosphere by undergoing a change in dimension. A lever system amplifies the relative displacement of the piston in the cylinder, and actuates the controlled valving device. This partial pressure oxygen sensing device is useful in controlled chemical reactions or in respiratory devices such as the oxygen demand meters for high altitude aircraft.

  1. The Thermal Pressure in Low Metallicity Galaxies

    NASA Astrophysics Data System (ADS)

    Wolfire, Mark; McKee, Christopher; Ostriker, Eve C.; Bolatto, Alberto; Jenkins, Edward

    2015-08-01

    The thermal pressure in the diffuse interstellar medium (ISM) is a relatively small fraction of the total ISM pressure yet it is extremely important for the evolution of the ISM phases. A multi-phase medium can exist between a range of thermal pressures Pmin < Pth < Pmax. The phase separation is driven by thermal instability and produces a cold (T ˜ 100 K) neutral atomic gas and a warm (T ˜ 8000 K) neutral atomic gas separated by thermally unstable gas. At thermal pressures greater than Pmax only the cold phase can exist and at thermal pressures less than Pmin only the warm phase can exist. The ISM is also highly turbulent and turbulence can both initiate the thermal phase transition and be produced in a rapid phase transition. Hydrodynamic modeling also points to a strong two-phase distribution (.e.g., Kim et al. 2011; Audit & Hennebelle 2010) with a median thermal pressure in the cold gas very near the expected two-phase pressure. Global, theoretical models including star-formation feedback have been developed for the molecular fraction in galactic disks using, at their core, the paradigm that thermal pressure determines the phase transitions to warm, cold, or multiphase medium (e.g., Krumholz et al. 2009; Ostriker et al. 2010).Here we present a phase diagram for a low metallicity galaxy using the Small Magellanic Clouds as an example. We find that although the heating rates and metallicities can differ by factors of 5 to 10 from the Milky Way, the resulting two-phase pressure and physical conditions of the phases are not very different from Galactic. We also confirm that a widely used fitting function for Pmin presented in Wolfire et al. 2003 provides an accurate prediction for the new results. We demonstrate how the variation in input parameters determine the final pressures and physical conditions.

  2. Variations on the Zilch Cycle

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    Thermo dynamic cycles in introductory physics courses are usually made up from a small number of permutations of isothermal, adiabatic, and constant-pressure and volume quasistatic strokes, with the working fluid usually being an ideal gas. Among them we find the Carnot, Stirling, Otto, Diesel, and Joule-Brayton cycles; in more advanced courses, steam cycles and refrigerators based on real working fluids are often introduced. Any additional cycles made up from the same simple strokes, and any extended analysis of known cycles, are welcome additions to the teaching repertory, as they provide more opportunities for practice and discussion. Our purpose in this note is to extend the analysis of the zilch cycle, introduced in Ref. 1, by presenting its TS diagram and by proposing several variations that do not contain adiabatic strokes, thus allowing a simpler mathematical treatment. As a bonus, we also provide results that make it possible to represent practically any elementary ideal-gas cycle in a TS diagram.

  3. Pressure measuring probe

    NASA Technical Reports Server (NTRS)

    Ashby, George C., Jr. (Inventor)

    1988-01-01

    The invention is a probe for measuring changes in pressure in a high velocity fluid stream over and adjacent to the surface of an object. The probe is formed of an exterior housing having a closed pressure chamber in which a piezoelectric pressure transducer is mounted. An open connector tube having a probe tip passes a portion of the fluid stream into the closed pressure chamber; any change of pressure within, which requires a settling-time to appear in the closed pressure chamber, is inversely proportional to the cross-sectional area of the connector tube. A cooling chamber formed around the pressure chamber is connected to a source of cooling fluid by means of inlet and outlet tubes.

  4. Pressure reducing regulator

    DOEpatents

    Whitehead, John C.; Dilgard, Lemoyne W.

    1995-01-01

    A pressure reducing regulator that controls its downstream or outlet pressure to a fixed fraction of its upstream or inlet pressure. The regulator includes a housing which may be of a titanium alloy, within which is located a seal or gasket at the outlet end which may be made of annealed copper, a rod, and piston, each of which may be made of high density graphite. The regulator is insensitive to temperature by virtue of being without a spring or gas sealed behind a diaphragm, and provides a reference for a system in which it is being used. The rod and piston of the regulator are constructed, for example, to have a 1/20 ratio such that when the downstream pressure is less than 1/20 of the upstream pressure the regulator opens and when the downstream pressure exceeds 1/20 of the upstream pressure the regulator closes.

  5. Pressure reducing regulator

    DOEpatents

    Whitehead, J.C.; Dilgard, L.W.

    1995-10-10

    A pressure reducing regulator that controls its downstream or outlet pressure to a fixed fraction of its upstream or inlet pressure is disclosed. The regulator includes a housing which may be of a titanium alloy, within which is located a seal or gasket at the outlet end which may be made of annealed copper, a rod, and piston, each of which may be made of high density graphite. The regulator is insensitive to temperature by virtue of being without a spring or gas sealed behind a diaphragm, and provides a reference for a system in which it is being used. The rod and piston of the regulator are constructed, for example, to have a 1/20 ratio such that when the downstream pressure is less than 1/20 of the upstream pressure the regulator opens and when the downstream pressure exceeds 1/20 of the upstream pressure the regulator closes. 10 figs.

  6. Miniaturized pressurization system

    DOEpatents

    Whitehead, John C.; Swink, Don G.

    1991-01-01

    The invention uses a fluid stored at a low pressure and provides the fluid at a high pressure. The invention allows the low pressure fluid to flow to a fluid bore of a differential pump and from the pump to a fluid pressure regulator. After flowing through the regulator the fluid is converted to a gas which is directed to a gas bore of the differential pump. By controlling the flow of gas entering and being exhausted from the gas bore, the invention provides pressure to the fluid. By setting the regulator, the high pressure fluid can be set at predetermined values. Because the invention only needs a low pressure fluid, the inventive apparatus has a low mass, and therefore would be useful in rocket propulsion systems.

  7. Pressure (Or No Royal Road)

    ERIC Educational Resources Information Center

    Bradley, J.

    1973-01-01

    Discusses how difficult the various problems of pressure, partial pressure, gas laws, and vapor pressure are for students. Outlines the evolution of the concept of pressure, the gas equation for a perfect gas, partial pressures, saturated vapor pressure, Avogadro's hypothesis, Raoult's law, and the vapor pressure of ideal solutions. (JR)

  8. Pressure locking test results

    SciTech Connect

    DeWall, K.G.; Watkins, J.C.; McKellar, M.G.; Bramwell, D.

    1996-12-01

    The U.S. Nuclear Regulatory Commission (NRC), Office of Nuclear Regulatory Research, is funding the Idaho National Engineering Laboratory (INEL) in performing research to provide technical input for their use in evaluating responses to Generic Letter 95-07, {open_quotes}Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves.{close_quotes} Pressure locking and thermal binding are phenomena that make a closed gate valve difficult to open. This paper discusses only the pressure locking phenomenon in a flexible-wedge gate valve; the authors will publish the results of their thermal binding research at a later date. Pressure locking can occur when operating sequences or temperature changes cause the pressure of the fluid in the bonnet (and, in most valves, between the discs) to be higher than the pressure on the upstream and downstream sides of the disc assembly. This high fluid pressure presses the discs against both seats, making the disc assembly harder to unseat than anticipated by the typical design calculations, which generally consider friction at only one of the two disc/seat interfaces. The high pressure of the bonnet fluid also changes the pressure distribution around the disc in a way that can further contribute to the unseating load. If the combined loads associated with pressure locking are very high, the actuator might not have the capacity to open the valve. The results of the NRC/INEL research discussed in this paper show that the relationship between bonnet pressure and pressure locking stem loads appears linear. The results also show that for this valve, seat leakage affects the bonnet pressurization rate when the valve is subjected to thermally induced pressure locking conditions.

  9. The Schwinger Variational Method

    NASA Technical Reports Server (NTRS)

    Huo, Winifred M.

    1995-01-01

    Variational methods have proven invaluable in theoretical physics and chemistry, both for bound state problems and for the study of collision phenomena. The application of the Schwinger variational (SV) method to e-molecule collisions and molecular photoionization has been reviewed previously. The present chapter discusses the implementation of the SV method as applied to e-molecule collisions. Since this is not a review of cross section data, cross sections are presented only to server as illustrative examples. In the SV method, the correct boundary condition is automatically incorporated through the use of Green's function. Thus SV calculations can employ basis functions with arbitrary boundary conditions. The iterative Schwinger method has been used extensively to study molecular photoionization. For e-molecule collisions, it is used at the static exchange level to study elastic scattering and coupled with the distorted wave approximation to study electronically inelastic scattering.

  10. Variation, Repetition, And Choice

    PubMed Central

    Abreu-Rodrigues, Josele; Lattal, Kennon A; dos Santos, Cristiano V; Matos, Ricardo A

    2005-01-01

    Experiment 1 investigated the controlling properties of variability contingencies on choice between repeated and variable responding. Pigeons were exposed to concurrent-chains schedules with two alternatives. In the REPEAT alternative, reinforcers in the terminal link depended on a single sequence of four responses. In the VARY alternative, a response sequence in the terminal link was reinforced only if it differed from the n previous sequences (lag criterion). The REPEAT contingency generated low, constant levels of sequence variation whereas the VARY contingency produced levels of sequence variation that increased with the lag criterion. Preference for the REPEAT alternative tended to increase directly with the degree of variation required for reinforcement. Experiment 2 examined the potential confounding effects in Experiment 1 of immediacy of reinforcement by yoking the interreinforcer intervals in the REPEAT alternative to those in the VARY alternative. Again, preference for REPEAT was a function of the lag criterion. Choice between varying and repeating behavior is discussed with respect to obtained behavioral variability, probability of reinforcement, delay of reinforcement, and switching within a sequence. PMID:15828592

  11. Cosmic ray biannual variation

    NASA Technical Reports Server (NTRS)

    Attolini, M. R.; Cecchini, S.; Cinicastagnoli, G.; Galli, M.

    1985-01-01

    The study of the cosmic ray (CR) power spectrum has revealed a significant variation with a period around 2 yr that cannot be explained as a high order harmonic of the 11 yr solar cycle. Comparative study of the correlation on different time scales between CR intensity and Rz, aa, high speed streams and polar hole size has put in evidence that a high degree of coherency exists between each couple of variables at 1.58 to 1.64 yr, except between CR and Rz. On the other hand cyclic variation on a short time scale, around 26 months, has been claimed to be present in the neutrino flux. Critical tests of this hypothesis are considered and a preliminary result seems to indicate that the hypothesis of the existence of a 1.6 yr periodicity in the neutrino data during the measurement time interval, has a significance or = 99.9%. The possible origin of this variation as due to a contribution either of CR interactions in the upper atmosphere or to the solar dynamics, are discussed.

  12. Canonical variate regression.

    PubMed

    Luo, Chongliang; Liu, Jin; Dey, Dipak K; Chen, Kun

    2016-07-01

    In many fields, multi-view datasets, measuring multiple distinct but interrelated sets of characteristics on the same set of subjects, together with data on certain outcomes or phenotypes, are routinely collected. The objective in such a problem is often two-fold: both to explore the association structures of multiple sets of measurements and to develop a parsimonious model for predicting the future outcomes. We study a unified canonical variate regression framework to tackle the two problems simultaneously. The proposed criterion integrates multiple canonical correlation analysis with predictive modeling, balancing between the association strength of the canonical variates and their joint predictive power on the outcomes. Moreover, the proposed criterion seeks multiple sets of canonical variates simultaneously to enable the examination of their joint effects on the outcomes, and is able to handle multivariate and non-Gaussian outcomes. An efficient algorithm based on variable splitting and Lagrangian multipliers is proposed. Simulation studies show the superior performance of the proposed approach. We demonstrate the effectiveness of the proposed approach in an [Formula: see text] intercross mice study and an alcohol dependence study. PMID:26861909

  13. Modeling flow in a pressure-sensitive, heterogeneous medium

    SciTech Connect

    Vasco, Donald W.; Minkoff, Susan E.

    2009-06-01

    Using an asymptotic methodology, including an expansion in inverse powers of {radical}{omega}, where {omega} is the frequency, we derive a solution for flow in a medium with pressure dependent properties. The solution is valid for a heterogeneous medium with smoothly varying properties. That is, the scale length of the heterogeneity must be significantly larger then the scale length over which the pressure increases from it initial value to its peak value. The resulting asymptotic expression is similar in form to the solution for pressure in a medium in which the flow properties are not functions of pressure. Both the expression for pseudo-phase, which is related to the 'travel time' of the transient pressure disturbance, and the expression for pressure amplitude contain modifications due to the pressure dependence of the medium. We apply the method to synthetic and observed pressure variations in a deforming medium. In the synthetic test we model one-dimensional propagation in a pressure-dependent medium. Comparisons with both an analytic self-similar solution and the results of a numerical simulation indicate general agreement. Furthermore, we are able to match pressure variations observed during a pulse test at the Coaraze Laboratory site in France.

  14. Climatic changes and variations: a geophysical problem

    SciTech Connect

    Newell, R. E.; Chiu, L. S.

    1980-01-01

    The morphology of, and the physical factors that control, the seasonal changes in global free air temperature and sea surface temperature are discussed. Non-seasonal tropical free air temperature changes are related to preceeding changes in tropical sea surface temperature and to volcanic aerosol while the tropical sea surface temperature itself is related to changes in surface pressure which characterize the Southern Oscillation. Zonal wind variations at low latitudes accompany the latter variations. The main variability in tropospheric temperature at high latitudes is characterized by the Greenland seesaw. The injection of volcanic aerosol by the eruption of Mt. Agung in March 1963 into the stratosphere gives rise to temperature increases of up to 5/sup 0/C in the stratosphere and cooling of 1/sup 0/C in the troposphere. The third major climatic signal in the recent record - the so called Biennial oscillation - is also briefly reviewed.

  15. Characterization of the Variation Potential in Sunflower.

    PubMed Central

    Stankovic, B.; Zawadzki, T.; Davies, E.

    1997-01-01

    A major candidate for intercellular signaling in higher plants is the stimulus-induced systemic change in membrane potential known as variation potential (VP). We investigated the mechanism of occurrence and long-distance propagation of VP in sunflower (Helianthus annuus L.) plants. Here we present evidence of the relationship among injury-induced changes in xylem tension, turgor pressure, and electrical potential. Although locally applied wounding did trigger a change in membrane potential, it evoked even faster changes in tissue deformation, apparently resulting from pressure surges rapidly transmitted through the xylem and experienced throughout the plant. Externally applied pressure mimicked flame wounding by triggering an electrical response resembling VP. Our findings suggest that VP in sunflower is not a propagating change in electrical potential and not the consequence of chemicals transmitted via the xylem, affecting ligand-modulated ion channels. Instead, VP appears to result from the surge in pressure in the xylem causing a change in activity of mechanosensitive, stretch-responsive ion channels or pumps in adjacent, living cells. The ensuing ion flux evokes local plasma membrane depolarization, which is monitored extracellularly as VP. PMID:12223859

  16. Blood Pressure Management Controversies in Neurocritical Care.

    PubMed

    McNett, Molly; Koren, Jay

    2016-03-01

    Blood pressure (BP) management is essential in neurocritical care settings to ensure adequate cerebral perfusion and prevent secondary brain injury. Despite consensus on the importance of BP monitoring, significant practice variations persist regarding optimal methods for monitoring and treatment of BP values among patients with neurologic injuries. This article provides a summary of research investigating various approaches for BP management in neurocritical care. Evidence-based recommendations, areas for future research, and current technological advancements for BP management are discussed. PMID:26873756

  17. Compressibility measurements of gases using externally heated pressure vessels.

    NASA Technical Reports Server (NTRS)

    Presnall, D. C.

    1971-01-01

    Most of the data collected under conditions of high temperature and pressure have been determined using a thick-walled bomb of carefully measured and fixed volume which is externally heated by an electric furnace or a thermostatically controlled bath. There are numerous variations on the basic method depending on the pressure-temperature range of interest, and the particular gas or gas mixture being studied. The construction and calibration of the apparatus is discussed, giving attention to the pressure vessel, the volume of the bomb, the measurement of pressure, the control and measurement of temperature, and the measurement of the amount and composition of gas in the bomb.

  18. Measurement of endolymphatic pressure.

    PubMed

    Mom, T; Pavier, Y; Giraudet, F; Gilain, L; Avan, P

    2015-04-01

    Endolymphatic pressure measurement is of interest both to researchers in the physiology and pathophysiology of hearing and ENT physicians dealing with Menière's disease or similar conditions. It is generally agreed that endolymphatic hydrops is associated with Menière's disease and is accompanied by increased hydrostatic pressure. Endolymphatic pressure, however, cannot be measured precisely without endangering hearing, making the association between hydrops and increased endolymphatic pressure difficult to demonstrate. Several integrated in vivo models have been developed since the 1960s, but only a few allow measurement of endolymphatic hydrostatic pressure. Models associating measurement of hydrostatic pressure and endolymphatic potential and assessment of cochlear function are of value to elucidate the pathophysiology of endolymphatic hydrops. The present article presents the main types of models and discusses their respective interest. PMID:25467202

  19. Blade pressure measurements

    NASA Astrophysics Data System (ADS)

    Chivers, J. W. H.

    Three measurement techniques which enable rotating pressures to be measured during the normal operation of a gas turbine or a component test rig are described. The first technique was developed specifically to provide steady and transient blade surface pressure data to aid both fan flutter research and general fan performance development. This technique involves the insertion of miniature high frequency response pressure transducers into the fan blades of a large civil gas turbine. The other two techniques were developed to measure steady rotating pressures inside and on the surface of engine or rig turbine blades and also rotating pressures in cooling feed systems. These two low frequency response systems are known as the "pressure pineapple' (a name which resulted from the shape of the original prototype) and the rotating scanivalve.

  20. High-pressure behavior of methylammonium lead iodide (MAPbI3) hybrid perovskite

    NASA Astrophysics Data System (ADS)

    Capitani, Francesco; Marini, Carlo; Caramazza, Simone; Postorino, Paolo; Garbarino, Gaston; Hanfland, Michael; Pisanu, Ambra; Quadrelli, Paolo; Malavasi, Lorenzo

    2016-05-01

    In this paper we provide an accurate high-pressure structural and optical study of the MAPbI3 hybrid perovskite. Structural data show the presence of a phase transition toward an orthorhombic structure around 0.3 GPa followed by full amorphization of the system above 3 GPa. After releasing the pressure, the system keeps the high-pressure orthorhombic phase. The occurrence of these structural transitions is further confirmed by pressure induced variations of the photoluminescence signal at high pressure. These variations clearly indicate that the bandgap value and the electronic structure of MAPI change across the phase transition.

  1. Pressure and Arc Voltage Measurement in a 252 kV SF6 Puffer Circuit Breaker

    NASA Astrophysics Data System (ADS)

    Zhong, Jianying; Guo, Yujing; Zhang, Hao

    2016-05-01

    The pressure distribution in an arcing chamber is critically important for the SF6 puffer circuit breaker design. In this paper, the pressure variation of four locations in the nozzle was measured by piezoresistive and fiber optical pressure sensors at two current levels of 10 kA and 50 kA. An arc voltage measurement was also taken. The results demonstrate that using either type of sensor with a connecting tube is able to detect the fast pressure variation in circuit breakers, however the possible distortion and delay to the pressure transient caused by the tube need further study.

  2. Diurnal Curve of the Ocular Perfusion Pressure

    PubMed Central

    Moreira, TCA; Bezerra, BSP; Vianello, MP; Corradi, J; Dorairaj, SK; Prata, TS

    2016-01-01

    ABSTRACT Purpose: To describe the diurnal variation of the ocular perfusion pressure (OPP) in normal, suspects and glaucoma patients. Materials and methods: Seventy-nine subjects were enrolled in a prospective study. The diurnal curve of intraocular pressure (IOP) was performed and blood pressure measurements were obtained. Each participant was grouped into one of the following based upon the clinical evaluation of the optic disk, IOP and standard achromatic perimetry (SAP): 18 eyes were classified as normal (normal SAP, normal optic disk evaluation and IOP < 21 mm Hg in two different measurements), 30 eyes as glaucoma suspect (GS) (normal SAP and mean deviation (MD), C/D ration > 0.5 or asymmetry > 0.2 and/or ocular hypertension), 31 eyes as early glaucoma (MD < -6 dB, glaucomatous optic neuropathy and SAP and MDs on SAP. Standard achromatic perimetry was performed with the Octopus 3.1.1 Dynamic 24-2 program. Intraocular pressure and blood pressure measurements were taken at 6 am, 9 am, 12, 3 and 6 pm. The patients stayed in the seated position for 5 minutes prior to blood pressure measurements. Results: The mean IOP values in all groups did not follow any regular pattern. The peak IOP was found to be greater in suspect [18.70 ± 3.31 (mm Hg ± SD)] and glaucoma (18.77 ± 4.30 mm Hg) patients as compared to normal subjects (16.11 ± 2.27 mm Hg). In studying the diurnal variation of the OPP, we found lower values at 3 pm in normals (34.21 ± 2.07 mm Hg), at 9 am in suspects (54.35 ± 3.32 mm Hg) and at 12 pm in glaucoma patients (34.84 ± 1.44 mm Hg). Conclusion: Each group has a specific OPP variation during the day with the most homogeneous group being the suspect one. It is important to keep studying the IOP and OPP variation for increased comprehension of the pathophysiology of glaucomatous optic neuropathy. How to cite this article: Kanadani FN, Moreira TCA, Bezerra BSP, Vianello MP, Corradi J, Dorairaj SK, Prata TS. Diurnal Curve of the Ocular Perfusion

  3. Liquid jet breakup regimes at supercritical pressures

    DOE PAGESBeta

    Oefelein, Joseph C.; Dahms, Rainer Norbert Uwe

    2015-07-23

    Previously, a theory has been presented that explains how discrete vapor–liquid interfaces become diminished at certain high-pressure conditions in a manner that leads to well known qualitative trends observed from imaging in a variety of experiments. Rather than surface tension forces, transport processes can dominate over relevant ranges of conditions. In this paper, this framework is now generalized to treat a wide range of fuel-oxidizer combinations in a manner consistent with theories of capillary flows and extended corresponding states theory. Different flow conditions and species-specific molecular properties are shown to produce distinct variations of interfacial structures and local free molecularmore » paths. These variations are shown to occur over the operating ranges in a variety of propulsion and power systems. Despite these variations, the generalized analysis reveals that the envelope of flow conditions at which the transition from classical sprays to diffusion-dominated mixing occurs exhibits a characteristic shape for all liquid–gas combinations. As a result, for alkane-oxidizer mixtures, it explains that these conditions shift to higher pressure flow conditions with increasing carbon number and demonstrates that, instead of widely assumed classical spray atomization, diffusion-dominated mixing may occur under relevant high-pressure conditions in many modern devices.« less

  4. Liquid jet breakup regimes at supercritical pressures

    SciTech Connect

    Oefelein, Joseph C.; Dahms, Rainer Norbert Uwe

    2015-07-23

    Previously, a theory has been presented that explains how discrete vapor–liquid interfaces become diminished at certain high-pressure conditions in a manner that leads to well known qualitative trends observed from imaging in a variety of experiments. Rather than surface tension forces, transport processes can dominate over relevant ranges of conditions. In this paper, this framework is now generalized to treat a wide range of fuel-oxidizer combinations in a manner consistent with theories of capillary flows and extended corresponding states theory. Different flow conditions and species-specific molecular properties are shown to produce distinct variations of interfacial structures and local free molecular paths. These variations are shown to occur over the operating ranges in a variety of propulsion and power systems. Despite these variations, the generalized analysis reveals that the envelope of flow conditions at which the transition from classical sprays to diffusion-dominated mixing occurs exhibits a characteristic shape for all liquid–gas combinations. As a result, for alkane-oxidizer mixtures, it explains that these conditions shift to higher pressure flow conditions with increasing carbon number and demonstrates that, instead of widely assumed classical spray atomization, diffusion-dominated mixing may occur under relevant high-pressure conditions in many modern devices.

  5. Macroscopic theory for capillary-pressure hysteresis.

    PubMed

    Athukorallage, Bhagya; Aulisa, Eugenio; Iyer, Ram; Zhang, Larry

    2015-03-01

    In this article, we present a theory of macroscopic contact angle hysteresis by considering the minimization of the Helmholtz free energy of a solid-liquid-gas system over a convex set, subject to a constant volume constraint. The liquid and solid surfaces in contact are assumed to adhere weakly to each other, causing the interfacial energy to be set-valued. A simple calculus of variations argument for the minimization of the Helmholtz energy leads to the Young-Laplace equation for the drop surface in contact with the gas and a variational inequality that yields contact angle hysteresis for advancing/receding flow. We also show that the Young-Laplace equation with a Dirichlet boundary condition together with the variational inequality yields a basic hysteresis operator that describes the relationship between capillary pressure and volume. We validate the theory using results from the experiment for a sessile macroscopic drop. Although the capillary effect is a complex phenomenon even for a droplet as various points along the contact line might be pinned, the capillary pressure and volume of the drop are scalar variables that encapsulate the global quasistatic energy information for the entire droplet. Studying the capillary pressure versus volume relationship greatly simplifies the understanding and modeling of the phenomenon just as scalar magnetic hysteresis graphs greatly aided the modeling of devices with magnetic materials. PMID:25646688

  6. High temperature pressure gauge

    DOEpatents

    Echtler, J. Paul; Scandrol, Roy O.

    1981-01-01

    A high temperature pressure gauge comprising a pressure gauge positioned in fluid communication with one end of a conduit which has a diaphragm mounted in its other end. The conduit is filled with a low melting metal alloy above the diaphragm for a portion of its length with a high temperature fluid being positioned in the remaining length of the conduit and in the pressure gauge.

  7. Pressure cryocooling protein crystals

    DOEpatents

    Kim, Chae Un; Gruner, Sol M.

    2011-10-04

    Preparation of cryocooled protein crystal is provided by use of helium pressurizing and cryocooling to obtain cryocooled protein crystal allowing collection of high resolution data and by heavier noble gas (krypton or xenon) binding followed by helium pressurizing and cryocooling to obtain cryocooled protein crystal for collection of high resolution data and SAD phasing simultaneously. The helium pressurizing is carried out on crystal coated to prevent dehydration or on crystal grown in aqueous solution in a capillary.

  8. 46 CFR 197.462 - Pressure vessels and pressure piping.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Pressure vessels and pressure piping. 197.462 Section... Diving Equipment § 197.462 Pressure vessels and pressure piping. (a) The diving supervisor shall ensure that each pressure vessel, including each volume tank, cylinder and PVHO, and each pressure...

  9. 46 CFR 197.462 - Pressure vessels and pressure piping.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Pressure vessels and pressure piping. 197.462 Section... Diving Equipment § 197.462 Pressure vessels and pressure piping. (a) The diving supervisor shall ensure that each pressure vessel, including each volume tank, cylinder and PVHO, and each pressure...

  10. 46 CFR 197.462 - Pressure vessels and pressure piping.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Pressure vessels and pressure piping. 197.462 Section... Diving Equipment § 197.462 Pressure vessels and pressure piping. (a) The diving supervisor shall ensure that each pressure vessel, including each volume tank, cylinder and PVHO, and each pressure...

  11. Effect of the initial pressure of multicomponent bubble media on the characteristics of detonation waves

    NASA Astrophysics Data System (ADS)

    Sychev, A. I.

    2016-05-01

    The effect of the initial pressure of multicomponent bubble media on the conditions of initiation, the structure, the velocity, and the pressure of detonation waves is experimentally studied. The variation of the initial pressure of a bubble medium is found to be an effective method to control the parameters of bubble detonation waves.

  12. Sapphire tube pressure vessel

    SciTech Connect

    Outwater, J.O.

    2000-05-23

    A pressure vessel is provided for observing corrosive fluids at high temperatures and pressures. A transparent Teflon bag contains the corrosive fluid and provides an inert barrier. The Teflon bag is placed within a sapphire tube, which forms a pressure boundary. The tube is received within a pipe including a viewing window. The combination of the Teflon bag, sapphire tube and pipe provides a strong and inert pressure vessel. In an alternative embodiment, tie rods connect together compression fittings at opposite ends of the sapphire tube.

  13. Pressure-sensitive optrode

    DOEpatents

    Hirschfeld, T.B.

    1985-04-09

    An apparatus and method are disclosed for sensing changes in pressure and for generating optical signals related to changes in pressure. Light from a fiber optic is directed to a movable surface which is coated with a light-responsive material, and which moves relative to the end of the fiber optic in response to changes in pressure. The same fiber optic collects a portion of the reflected or emitted light from the movable surface. Changes in pressure are determined by measuring changes in the amount of light collected. 5 figs.

  14. Pressure-sensitive optrode

    DOEpatents

    Hirschfeld, Tomas B.

    1985-01-01

    Apparatus and method for sensing changes in pressure and for generating optical signals related to changes in pressure. Light from a fiber optic is directed to a movable surface which is coated with a light-responsive material, and which moves relative to the end of the fiber optic in response to changes in pressure. The same fiber optic collects a portion of the reflected or emitted light from the movable surface. Changes in pressure are determined by measuring changes in the amount of light collected.

  15. Pressurized fluidized bed reactor

    DOEpatents

    Isaksson, J.

    1996-03-19

    A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine. 1 fig.

  16. CC Pressure Test

    SciTech Connect

    Dixon, K.; /Fermilab

    1990-07-12

    The inner vessel heads including bypass and beam tubes had just been welded into place and dye penetrant checked. The vacuum heads were not on at this time but the vacuum shell was on covering the piping penetrating into the inner vessel. Signal boxes with all feed through boards, the instrumentation box, and high voltage boxes were all installed with their pump outs capped. All 1/4-inch instrumentation lines were terminated at their respective shutoff valves. All vacuum piping used for pumping down the inner vessel was isolated using o-ring sealed blind flanges. PV215A (VAT Series 12), the 4-inch VRC gate valve isolating the cyropump, and the rupture disk had to be removed and replaced with blind flanges before pressurizing due to their pressure limitations. Stresses in plates used as blind flanges were checked using Code calcualtions. Before the CC test, vacuum style blanks and clamps were hydrostatically pressure tested to 150% of the maximum test pressure, 60 psig. The Code inspector and Research Division Safety had all given their approval to the test pressure and procedure prior to filling the vessel with argon. The test was a major success. Based on the lack of any distinguishable pressure drop indicated on the pressure gages, the vessel appeared to be structurally sound throughout the duration of the test (approx. 3 hrs.). A major leak in the instrumentation tubing was discovered at half of the maximum test pressure and was quickly isolated by crimping and capping with a compression fitting. There were some slight deviations in the actual procedure used. The 44 psig relief valve located just outside the cleanroom had to be capped until the pressure in the vessel indicated 38 psi. This was to allow higher supply pressures and hence, higher flows through the pressurizing line. Also, in order to get pressure readings at the cryostat without exposing any personnel to the potentially dangerous stored energy near the maximum test pressure, a camera was installed

  17. Sapphire tube pressure vessel

    DOEpatents

    Outwater, John O.

    2000-01-01

    A pressure vessel is provided for observing corrosive fluids at high temperatures and pressures. A transparent Teflon bag contains the corrosive fluid and provides an inert barrier. The Teflon bag is placed within a sapphire tube, which forms a pressure boundary. The tube is received within a pipe including a viewing window. The combination of the Teflon bag, sapphire tube and pipe provides a strong and inert pressure vessel. In an alternative embodiment, tie rods connect together compression fittings at opposite ends of the sapphire tube.

  18. Pressurized fluidized bed reactor

    DOEpatents

    Isaksson, Juhani

    1996-01-01

    A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine.

  19. Pressure-sensitive optrode

    DOEpatents

    Hirschfeld, T.B.

    1982-09-30

    Apparatus and method for sensing changes in pressure and for generating optical signals related to changes in pressure. Light from a fiber optic is directed to a movable surface which is coated with a light-responsive material, and which moves relative to the end of the fiber optic in response to changes in pressure. The same fiber optic collects a portion of the reflected or emitted light from the movable surface. Changes in pressure are determined by measuring changes in the amount of light collected.

  20. Blood Pressure Control

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Engineering Development Laboratory developed a system for the cardiovascular study of weightless astronauts. This was designed to aid people with congestive heart failure and diabetes. While in space, astronauts' blood pressure rises, heart rate becomes unstable, and there are sometimes postflight lightheadedness or blackouts. The Baro-Cuff studies the resetting of blood pressure. When a silicone rubber chamber is strapped to the neck, the Baro-Cuff stimulates the carotid arteries by electronically controlled pressure application. Blood pressure controls in patients may be studied.

  1. Blood Pressure vs. Heart Rate

    MedlinePlus

    ... High Blood Pressure Tools & Resources Stroke More Blood Pressure vs. Heart Rate Updated:Aug 30,2016 Blood ... last reviewed on 08/04/2014. High Blood Pressure • Home • About High Blood Pressure (HBP) Introduction What ...

  2. Attachment Fitting for Pressure Vessel

    NASA Technical Reports Server (NTRS)

    Smeltzer, Stanley S., III (Inventor); Carrigan, Robert W. (Inventor)

    2002-01-01

    This invention provides sealed access to the interior of a pressure vessel and consists of a tube. a collar, redundant seals, and a port. The port allows the seals to be pressurized and seated before the pressure vessel becomes pressurized.

  3. Socioeconomic Status Modifies the Seasonal Effect on Blood Pressure

    PubMed Central

    Cois, Annibale; Ehrlich, Rodney

    2015-01-01

    Abstract Seasonal variations in blood pressure have been consistently reported. However, uncertainty remains about the size of the seasonal effect in different regions, and about factors that explain the differences observed across and within populations. Using data from a national panel study, we investigated seasonal variations in blood pressure in the South African adult population, and whether these variations differed across socioeconomic strata. We estimated age-specific seasonal effects on blood pressure using a multilevel structural equation model, with repeated measurements nested within subjects. Effect modification by socioeconomic status was assessed by repeating the analyses in the subpopulations defined by levels of education, household income per capita, and type of housing. In men and women, season had a statistically significant effect on blood pressure, with higher levels in winter and lower levels in summer. For systolic blood pressure, the magnitude of the seasonal effect was 4.25/4.21 mmHg (women/men) and was higher in the older age groups. For diastolic blood pressure, the effect size was 4.00/4.01 mmHg, with no evident age trend. Seasonal effects were higher among subjects in the lowest socioeconomic classes than in the highest, with differences between 2.4 and 7.7 mmHg, depending on gender, whether systolic or diastolic blood pressure, and socioeconomic status indicator. In the South African adult population, blood pressure shows seasonal variation modified by age and socioeconomic status. These variations have epidemiological, clinical, and public health implications, including the prospect of population level intervention to reduce elevated risk of cold weather cardiovascular morbidity. PMID:26334893

  4. Pressure-morphology relationship of a released carpal tunnel.

    PubMed

    Kim, Dong Hee; Marquardt, Tamara L; Gabra, Joseph N; Shen, Zhilei Liu; Evans, Peter J; Seitz, William H; Li, Zong-Ming

    2013-04-01

    We investigated morphological changes of a released carpal tunnel in response to variations of carpal tunnel pressure. Pressure within the carpal tunnel is known to be elevated in patients with carpal tunnel syndrome and dependent on wrist posture. Previously, increased carpal tunnel pressure was shown to affect the morphology of the carpal tunnel with an intact transverse carpal ligament (TCL). However, the pressure-morphology relationship of the carpal tunnel after release of the TCL has not been investigated. Carpal tunnel release (CTR) was performed endoscopically on cadaveric hands and the carpal tunnel pressure was dynamically increased from 10 to 120 mmHg. Simultaneously, carpal tunnel cross-sectional images were captured by an ultrasound system, and pressure measurements were recorded by a pressure transducer. Carpal tunnel pressure significantly affected carpal arch area (p < 0.001), with an increase of >62 mm(2) at 120 mmHg. Carpal arch height, length, and width also significantly changed with carpal tunnel pressure (p < 0.05). As carpal tunnel pressure increased, carpal arch height and length increased, but the carpal arch width decreased. Analyses of the pressure-morphology relationship for a released carpal tunnel revealed a nine times greater compliance than that previously reported for a carpal tunnel with an intact TCL. This change of structural properties as a result of transecting the TCL helps explain the reduction of carpal tunnel pressure and relief of symptoms for patients after CTR surgery. PMID:23184493

  5. Biomechanical modeling to prevent ischial pressure ulcers.

    PubMed

    Luboz, Vincent; Petrizelli, Marion; Bucki, Marek; Diot, Bruno; Vuillerme, Nicolas; Payan, Yohan

    2014-07-18

    With 300,000 paraplegic persons only in France, ischial pressure ulcers represent a major public health issue. They result from the buttocks׳ soft tissues compression by the bony prominences. Unfortunately, the current clinical techniques, with - in the best case - embedded pressure sensor mats, are insufficient to prevent them because most are due to high internal strains which can occur even with low pressures at the skin surface. Therefore, improving prevention requires using a biomechanical model to estimate internal strains from skin surface pressures. However, the buttocks׳ soft tissues׳ stiffness is still unknown. This paper provides a stiffness sensitivity analysis using a finite element model. Different layers with distinct Neo Hookean materials simulate the skin, fat and muscles. With Young moduli in the range [100-500 kPa], [25-35 kPa], and [80-140 kPa] for the skin, fat, and muscles, respectively, maximum internal strains reach realistic 50 to 60% values. The fat and muscle stiffnesses have an important influence on the strain variations, while skin stiffness is less influent. Simulating different sitting postures and changing the muscle thickness also result in a variation in the internal strains. PMID:24873863

  6. Variational Approach to SAW

    NASA Astrophysics Data System (ADS)

    Burlatsky, Sergei F.; Reinhardt, S.; Lach; Ovchinnikov, Yu.

    1996-03-01

    A new variational technique is used to analyze both analytically and numerically the scaling behavior of Self Avoiding Walks. We present a set of lower bounds for the survival provability (the ratio of total number of self avoiding paths to total number of random paths) which is based on Jensen inequality. This set is generated by the hierarchy of different trial hamiltonians which correspond to: unconstrained random walk, mean field approximation, original Flory model and to a new approach which allows to vary independently the scales of fluctuations, corresponding to different path length scales. The D=2, D=3, and Darrow 4, cases are analyzed separately. The results of analytical variational procedure reproduce classical mean field exponents for small scales and Flory - type critical exponents for large scales, and present new estimates for the chemical potential of SAW. Possible generalizations to branching self avoiding paths are discussed. The numerical algorithm which is based on proposed trial hamiltonian might increase the efficiency with which the chemical potential and scaling properties of chain molecules with a finite number of discrete conformations can be computed. This work was supported in part by ONR Grant N00014-94-0647.

  7. Harmonically excited orbital variations

    SciTech Connect

    Morgan, T.

    1985-08-06

    Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs.

  8. Anisotropic Total Variation Filtering

    SciTech Connect

    Grasmair, Markus; Lenzen, Frank

    2010-12-15

    Total variation regularization and anisotropic filtering have been established as standard methods for image denoising because of their ability to detect and keep prominent edges in the data. Both methods, however, introduce artifacts: In the case of anisotropic filtering, the preservation of edges comes at the cost of the creation of additional structures out of noise; total variation regularization, on the other hand, suffers from the stair-casing effect, which leads to gradual contrast changes in homogeneous objects, especially near curved edges and corners. In order to circumvent these drawbacks, we propose to combine the two regularization techniques. To that end we replace the isotropic TV semi-norm by an anisotropic term that mirrors the directional structure of either the noisy original data or the smoothed image. We provide a detailed existence theory for our regularization method by using the concept of relaxation. The numerical examples concluding the paper show that the proposed introduction of an anisotropy to TV regularization indeed leads to improved denoising: the stair-casing effect is reduced while at the same time the creation of artifacts is suppressed.

  9. Variations in brain DNA

    PubMed Central

    Avila, Jesús; Gómez-Ramos, Alberto; Soriano, Eduardo

    2014-01-01

    It is assumed that DNA sequences are conserved in the diverse cell types present in a multicellular organism like the human being. Thus, in order to compare the sequences in the genome of DNA from different individuals, nucleic acid is commonly isolated from a single tissue. In this regard, blood cells are widely used for this purpose because of their availability. Thus blood DNA has been used to study genetic familiar diseases that affect other tissues and organs, such as the liver, heart, and brain. While this approach is valid for the identification of familial diseases in which mutations are present in parental germinal cells and, therefore, in all the cells of a given organism, it is not suitable to identify sporadic diseases in which mutations might occur in specific somatic cells. This review addresses somatic DNA variations in different tissues or cells (mainly in the brain) of single individuals and discusses whether the dogma of DNA invariance between cell types is indeed correct. We will also discuss how single nucleotide somatic variations arise, focusing on the presence of specific DNA mutations in the brain. PMID:25505410

  10. Climatic variation of storms

    NASA Technical Reports Server (NTRS)

    Fujita, Ted

    1993-01-01

    Long-term variation of U.S. tornadoes were studied by obtaining the best possible data during the 75 years, 1916-90. The most difficult task was to estimate the number of early tornadoes in 1916-50 when the reporting efficiency was very bad, resulting in undercounting of the incidents. In generating the best possible data, Fujita's Tornado Tape produced at the University of Chicago, the book Significant Tornadoes, 1880-1989, by Thomas P. Grazulis, and the NSSFC Tornado Tape were combined. First, the annual number of tornadoes were smoothed to obtain the smoothed number of annual tornadoes which was normalized to the standard number of tornadoes defined as the mean number in the recent 30 years 1960-89. The normalization factor was obtained by computing the ration of smoothed and standard number. In the early years, the factor was in excess of 7. Thereafter, the normalized number of annual tornadoes was computed and plotted, finding that the results are very satisfactory. In order to visualize the variation of tornado activities, the tornado activity number (TAN) was initiated and computed. The TAN including all annual tornadoes show certain periodicity. For climatological evaluation, the peak-activity day of each year, such as Superoutbreak day, 3 April 1974, Palm Sunday, 11 April 1965 were eliminated. The TAN, excluding peak-day tornadoes, is of extreme interest.

  11. Pressurized Pepsin Digestion in Proteomics

    PubMed Central

    López-Ferrer, Daniel; Petritis, Konstantinos; Robinson, Errol W.; Hixson, Kim K.; Tian, Zhixin; Lee, Jung Hwa; Lee, Sang-Won; Tolić, Nikola; Weitz, Karl K.; Belov, Mikhail E.; Smith, Richard D.; Paša-Tolić, Ljiljana

    2011-01-01

    Integrated top-down bottom-up proteomics combined with on-line digestion has great potential to improve the characterization of protein isoforms in biological systems and is amendable to high throughput proteomics experiments. Bottom-up proteomics ultimately provides the peptide sequences derived from the tandem MS analyses of peptides after the proteome has been digested. Top-down proteomics conversely entails the MS analyses of intact proteins for more effective characterization of genetic variations and/or post-translational modifications. Herein, we describe recent efforts toward efficient integration of bottom-up and top-down LC-MS-based proteomics strategies. Since most proteomics separations utilize acidic conditions, we exploited the compatibility of pepsin (where the optimal digestion conditions are at low pH) for integration into bottom-up and top-down proteomics work flows. Pressure-enhanced pepsin digestions were successfully performed and characterized with several standard proteins in either an off-line mode using a Barocycler or an on-line mode using a modified high pressure LC system referred to as a fast on-line digestion system (FOLDS). FOLDS was tested using pepsin and a whole microbial proteome, and the results were compared against traditional trypsin digestions on the same platform. Additionally, FOLDS was integrated with a RePlay configuration to demonstrate an ultrarapid integrated bottom-up top-down proteomics strategy using a standard mixture of proteins and a monkey pox virus proteome. PMID:20627868

  12. Dual shell pressure balanced vessel

    DOEpatents

    Fassbender, Alexander G.

    1992-01-01

    A dual-wall pressure balanced vessel for processing high viscosity slurries at high temperatures and pressures having an outer pressure vessel and an inner vessel with an annular space between the vessels pressurized at a pressure slightly less than or equivalent to the pressure within the inner vessel.

  13. Measuring Surface Pressure on Rotating Compressor Blades Using Pressure Sensitive Paint.

    PubMed

    Pastuhoff, Markus; Tillmark, Nils; Alfredsson, P Henrik

    2016-01-01

    Pressure sensitive paint (PSP) was used to measure pressure on the blades of a radial compressor with a 51 mm inlet diameter rotating at speeds up to 50 krpm using the so called lifetime method. A diode laser with a scanning-mirror system was used to illuminate the paint and the luminescent lifetime was registered using a photo multiplier. With the described technique the surface-pressure fields were acquired for eight points in the compressor map, useful for general understanding of the flow field and for CFD validation. The PSP was of so called fast type, which makes it possible to observe pressure variations with frequencies up to several kHz. Through frequency spectrum analysis we were able to detect the pulsating flow frequency when the compressor was driven to surge. PMID:27005623

  14. Measuring Surface Pressure on Rotating Compressor Blades Using Pressure Sensitive Paint

    PubMed Central

    Pastuhoff, Markus; Tillmark, Nils; Alfredsson, P. Henrik

    2016-01-01

    Pressure sensitive paint (PSP) was used to measure pressure on the blades of a radial compressor with a 51 mm inlet diameter rotating at speeds up to 50 krpm using the so called lifetime method. A diode laser with a scanning-mirror system was used to illuminate the paint and the luminescent lifetime was registered using a photo multiplier. With the described technique the surface-pressure fields were acquired for eight points in the compressor map, useful for general understanding of the flow field and for CFD validation. The PSP was of so called fast type, which makes it possible to observe pressure variations with frequencies up to several kHz. Through frequency spectrum analysis we were able to detect the pulsating flow frequency when the compressor was driven to surge. PMID:27005623

  15. Laryngeal pressure receptors.

    PubMed

    Mathew, O P; Sant'Ambrogio, G; Fisher, J T; Sant'Ambrogio, F B

    1984-07-01

    We studied the response characteristics of laryngeal pressure receptors in anesthetized dogs, breathing through a tracheal cannula, by recording single unit action potentials from the peripheral cut end of the internal branch of the superior laryngeal nerve. The larynx, with the rest of the upper airway, was isolated and cannulated separately for the application of distending and collapsing pressures. We identified receptors responding to either negative or positive pressure and a few responding to both. All these receptors showed a marked dynamic sensitivity and had the characteristics of slowly adapting mechanoreceptors. The majority of pressure receptors were active at zero transmural pressure and the gain of their response to pressure was higher at lower values, suggesting a role for these receptors in eupnea. Reflex alterations in breathing pattern and upper airway muscle activity during upper airway pressure changes, previously reported, are presumably mediated by the receptors described here. Moreover, these receptors may play a role in certain pathological states, such as obstructive sleep apnea, in which the upper airway is transiently subjected to large collapsing pressure. PMID:6484319

  16. Pressure vessel flex joint

    NASA Technical Reports Server (NTRS)

    Kahn, Jon B. (Inventor)

    1992-01-01

    An airtight, flexible joint is disclosed for the interfacing of two pressure vessels such as between the Space Station docking tunnel and the Space Shuttle Orbiter bulkhead adapter. The joint provides for flexibility while still retaining a structural link between the two vessels required due to the loading created by the internal/external pressure differential. The joint design provides for limiting the axial load carried across the joint to a specific value, a function returned in the Orbiter/Station tunnel interface. The flex joint comprises a floating structural segment which is permanently attached to one of the pressure vessels through the use of an inflatable seal. The geometric configuration of the joint causes the tension between the vessels created by the internal gas pressure to compress the inflatable seal. The inflation pressure of the seal is kept at a value above the internal/external pressure differential of the vessels in order to maintain a controlled distance between the floating segment and pressure vessel. The inflatable seal consists of either a hollow torus-shaped flexible bladder or two rolling convoluted diaphragm seals which may be reinforced by a system of straps or fabric anchored to the hard structures. The joint acts as a flexible link to allow both angular motion and lateral displacement while it still contains the internal pressure and holds the axial tension between the vessels.

  17. Neonatal Pressure Ulcer Prevention.

    PubMed

    Scheans, Patricia

    2015-01-01

    The incidence of pressure ulcers in acutely ill infants and children ranges up to 27 percent in intensive care units, with a range of 16-19 percent in NICUs. Anatomic, physiologic, and developmental factors place ill and preterm newborns at risk for skin breakdown. Two case studies illustrate these factors, and best practices for pressure ulcer prevention are described. PMID:26803094

  18. High pressure nitriding

    SciTech Connect

    Jung, M.; Hoffmann, F.T.; Mayr, P.; Minarski, P.

    1995-12-31

    The aim of the presented research project is the development of a new high pressure nitriding process, which avoids disadvantages of conventional nitriding processes and allows for new applications. Up to now, a nitriding furnace has been constructed and several investigations have been made in order to characterize the influence of pressure on the nitriding process. In this paper, connections between pressure in the range of 2 to 12 atm and the corresponding nitride layer formation for the steel grades AISI 1045, H11 and a nitriding steel are discussed. Results of the nitride layer formation are presented. For all steel grades, a growth of nitride layers with increasing pressure was obtained. Steels with passive layers, as the warm working steel H11, showed a better nitriding behavior at elevated pressure.

  19. Summing pressure compensation control

    SciTech Connect

    Myers, H.A.

    1988-04-26

    This patent describes a summing pressure compensator control for hydraulic loads with at least one of the hydraulic loads being a variable displacement motor having servo means for controlling the displacement thereof, first hydraulic means responsive to the supply of fluid to the variable displacement motor to provide a first pressure signal, second hydraulic means responsive to the supply of fluid to a second hydraulic load to provide a second pressure signal, summing means for receiving the first and second pressure signals and providing a control signal proportional to the sum of the first and second pressure signals, the control signal being applied to the servo means to increase the displacement of the variable displacement motor.

  20. PRESSURE ACTIVATED SEALANT TECHNOLOGY

    SciTech Connect

    Michael A. Romano

    2004-04-01

    The objective of this project is to develop new, efficient, cost effective methods of internally sealing natural gas pipeline leaks through the application of differential pressure activated sealants. In researching the current state of the art for gas pipeline sealing technologies we concluded that if the project was successful, it appeared that pressure activated sealant technology would provide a cost effective alternative to existing pipeline repair technology. From our analysis of current field data for a 13 year period from 1985 to 1997 we were able to identify 205 leaks that were candidates for pressure activated sealant technology, affirming that pressure activated sealant technology is a viable option to traditional external leak repairs. The data collected included types of defects, areas of defects, pipe sizes and materials, incident and operating pressures, ability of pipeline to be pigged and corrosion states. This data, and subsequent analysis, was utilized as a basis for constructing applicable sealant test modeling.

  1. Blood pressure evaluation using sphygmomanometry assisted by arterial pulse waveform detection by fiber Bragg grating pulse device

    NASA Astrophysics Data System (ADS)

    Sharath, Umesh; Sukreet, Raju; Apoorva, Girish; Asokan, Sundarrajan

    2013-06-01

    We report a blood pressure evaluation methodology by recording the radial arterial pulse waveform in real time using a fiber Bragg grating pulse device (FBGPD). Here, the pressure responses of the arterial pulse in the form of beat-to-beat pulse amplitude and arterial diametrical variations are monitored. Particularly, the unique signatures of pulse pressure variations have been recorded in the arterial pulse waveform, which indicate the systolic and diastolic blood pressure while the patient is subjected to the sphygmomanometric blood pressure examination. The proposed method of blood pressure evaluation using FBGPD has been validated with the auscultatory method of detecting the acoustic pulses (Korotkoff sounds) by an electronic stethoscope.

  2. Blood pressure evaluation using sphygmomanometry assisted by arterial pulse waveform detection by fiber Bragg grating pulse device.

    PubMed

    Sharath, Umesh; Sukreet, Raju; Apoorva, Girish; Asokan, Sundarrajan

    2013-06-01

    We report a blood pressure evaluation methodology by recording the radial arterial pulse waveform in real time using a fiber Bragg grating pulse device (FBGPD). Here, the pressure responses of the arterial pulse in the form of beat-to-beat pulse amplitude and arterial diametrical variations are monitored. Particularly, the unique signatures of pulse pressure variations have been recorded in the arterial pulse waveform, which indicate the systolic and diastolic blood pressure while the patient is subjected to the sphygmomanometric blood pressure examination. The proposed method of blood pressure evaluation using FBGPD has been validated with the auscultatory method of detecting the acoustic pulses (Korotkoff sounds) by an electronic stethoscope. PMID:23804218

  3. An apparatus for studying scintillator properties at high isostatic pressures.

    PubMed

    Gaumé, R M; Lam, S; Gascón, M; Setyawan, W; Curtarolo, S; Feigelson, R S

    2013-01-01

    We describe the design and operation of a unique hydraulic press for the study of scintillator materials under isostatic pressure. This press, capable of developing a pressure of a gigapascal, consists of a large sample chamber pressurized by a two-stage hydraulic amplifier. The optical detection of the scintillation light emitted by the sample is performed, through a large aperture optical port, by a photodetector located outside the pressure vessel. In addition to providing essential pressure-dependent studies on the emission characteristics of radioluminescent materials, this apparatus is being developed to elucidate the mechanisms behind the recently observed dependency of light-yield nonproportionality on electronic band structure. The variation of the light output of a Tl:CsI crystal under 511-keV gamma excitation and hydrostatic pressure is given as an example. PMID:23387697

  4. An apparatus for studying scintillator properties at high isostatic pressures

    NASA Astrophysics Data System (ADS)

    Gaumé, R. M.; Lam, S.; Gascón, M.; Setyawan, W.; Curtarolo, S.; Feigelson, R. S.

    2013-01-01

    We describe the design and operation of a unique hydraulic press for the study of scintillator materials under isostatic pressure. This press, capable of developing a pressure of a gigapascal, consists of a large sample chamber pressurized by a two-stage hydraulic amplifier. The optical detection of the scintillation light emitted by the sample is performed, through a large aperture optical port, by a photodetector located outside the pressure vessel. In addition to providing essential pressure-dependent studies on the emission characteristics of radioluminescent materials, this apparatus is being developed to elucidate the mechanisms behind the recently observed dependency of light-yield nonproportionality on electronic band structure. The variation of the light output of a Tl:CsI crystal under 511-keV gamma excitation and hydrostatic pressure is given as an example.

  5. The effects of fatigue on plantar pressure distribution in walking.

    PubMed

    Bisiaux, M; Moretto, P

    2008-11-01

    The purpose of this study was to assess plantar pressure deviations due to fatigue. Plantar pressure was assessed using a portable system while eleven healthy subjects performed three walking tests, one before, one immediately after and another 30-min after intensive running. Pressure peak, intra-subject coefficient of variation and relative impulse were recorded. Significant decrease in pressure peak and the relative impulse under the heel and the midfoot along with significant increase in pressure peak and relative impulse under the forefoot were observed 30 min after the run. After a 30-min rest, the heel and forefoot loading remained significantly affected compared to the pre-test conditions while variability, step length and frequency remained unchanged. The study demonstrates short- and long-term plantar pressure deviations due to fatigue induced by an intensive 30-min run, while previous studies showed negligible deviation of the ground reaction force. PMID:18586495

  6. Barotrauma with extreme pressures in sport: from scuba to skydiving.

    PubMed

    Lynch, James H; Deaton, Travis G

    2014-01-01

    The human body is well adapted to dealing with small variations in atmospheric pressure. However when our pursuit of sport and recreation takes us to extreme altitudes or ocean depths, the change in surrounding pressure has the potential to cause significant morbidity. Sports with more extreme changes in atmospheric pressure such as skydiving and scuba diving commonly place the athlete at risk for barotrauma injuries, especially in the middle ear and sinuses. Middle ear barotrauma occurs when a pressure differential develops between the middle ear and the pressure outside of the tympanic membrane. Early symptoms include ear pain, dizziness, and muffled hearing. When extreme pressure gradients are not relieved, middle ear effusions and rupture of the tympanic membrane can occur. A similar mechanism and injury pattern occurs in the sinuses as well. With proper training and prevention strategies, athletes in these sports can protect themselves from most barotrauma injuries. PMID:24614424

  7. Total-pressure-tube averaging in pulsating flows.

    NASA Technical Reports Server (NTRS)

    Krause, L. N.

    1973-01-01

    A number of total-pressure tubes were tested in a nonsteady flow generator in which the fraction of period that pressure is a maximum is approximately 0.8, thereby simulating turbomachine-type flow conditions. The tests were performed at a pressure level of 1 bar, for Mach numbers up to near 1, and frequencies up to 3 kHz. Most of the tubes indicated a pressure which was higher than the true average. Organ-pipe resonances which further increased the indicated pressure were encountered within the tubes at discrete frequencies. There was no obvious combination of tube diameter, length, and/or geometry variation used in the tests which resulted in negligible averaging error. A pneumatic-type probe was found to measure true average pressure, and is suggested as a comparison instrument to determine whether nonlinear averaging effects are serious in unknown pulsation profiles.

  8. Microseismicity Induced by Fluid Pressure Drop (Laboratory Study)

    NASA Astrophysics Data System (ADS)

    Turuntaev, Sergey; Zenchenko, Evgeny; Melchaeva, Olga

    2013-04-01

    gradient maximal values. The model of AE relation with the pore pressure gradient was considered based on the following assumptions: AE event occurred when the pore pressure gradient reaches some critical value; the critical value varies and can be described by Weibull distribution. Permeability variation during the fluid pressure drop was estimated by means of fluid pressure data and pore-elastic equation solution for small time intervals (0.01 sec). The study showed possibility to solve both a direct problem of microseismicity variation relation with fluid pressure changes and an inverse problem of defining permeability by registering microseismic activity variation in particular volume of porous medium alongside with pore pressure measurements at some point.

  9. Determination of the partial pressure of thallium in high-pressure lamp arcs: A comparative study

    SciTech Connect

    Karabourniotis, D.; Couris, S.; Damelincourt, J.J.; Aubes, M.

    1986-08-01

    The partial pressure of thallium in high-pressure Hg-TlI discharges with different mercury, thallium, and electron pressures has been measured by using the optically thin line Tl 655 nm and the self-reversed line Tl 535 nm. The partial pressure of the arc axis has been measured from the line Tl 655nm. The effective partial pressure has been measured from the self-reversed line Tl 535 nm on the basis of the multiparameter method, and it has been calculated from the known axis pressure of thallium and the calculation of its radial variation by taking into account the chemical reactions. The experimental results confirm the dispersion character of the blue wing of the line Tl 535 nm. The systematic difference obtained between the measured and calculated effective pressure, particularly at the moment of minimum electron density, may be interpreted by deviations from the local thermodynamic equilibrium (LTE) caused by overpopulation of the upper level of the line Tl 535 nm.

  10. Pressure Measurement Systems

    NASA Technical Reports Server (NTRS)

    1990-01-01

    System 8400 is an advanced system for measurement of gas and liquid pressure, along with a variety of other parameters, including voltage, frequency and digital inputs. System 8400 offers exceptionally high speed data acquisition through parallel processing, and its modular design allows expansion from a relatively inexpensive entry level system by the addition of modular Input Units that can be installed or removed in minutes. Douglas Juanarena was on the team of engineers that developed a new technology known as ESP (electronically scanned pressure). The Langley ESP measurement system was based on miniature integrated circuit pressure-sensing transducers that communicated pressure information to a minicomputer. In 1977, Juanarena formed PSI to exploit the NASA technology. In 1978 he left Langley, obtained a NASA license for the technology, introduced the first commercial product, the 780B pressure measurement system. PSI developed a pressure scanner for automation of industrial processes. Now in its second design generation, the DPT-6400 is capable of making 2,000 measurements a second and has 64 channels by addition of slave units. New system 8400 represents PSI's bid to further exploit the $600 million U.S. industrial pressure measurement market. It is geared to provide a turnkey solution to physical measurement.

  11. Master external pressure charts

    SciTech Connect

    Michalopoulos, E.

    1996-12-01

    This paper presents a method to develop master external pressure charts from which individual external pressure charts for each material specification may be derived. The master external charts can represent a grouping of materials with similar chemical composition, similar stress-strain curves but produced to different strength levels. External pressure charts are used by various Sections of the ASME Boiler and Pressure Vessel and Piping Codes to design various components such as cylinders, sphered, formed heads, tubes, piping, rings and other components, subjected to external pressure or axial compression loads. These charts are pseudo stress-strain curves for groups of materials with similar stress-strain shapes. The traditional approach was originally developed in the 1940`s and is a graphical approach where slopes to the strain curves are drawn graphically from which pseudo-strain levels are calculated. The new method presented in this paper develops mathematical relationships for the material stress-strain curves and the external pressure charts. The method has the ability to calculate stress-strain curves from existing external pressure charts. The relationships are a function of temperature, the modulus of elasticity, yield strength, and two empirical material constants. In this approach, conservative assumptions used to assign materials to lower bound external pressure charts can be removed. This increases the buckling strength capability of many materials in the Code, providing economic benefits while maintaining the margin of safety specified by the Code criteria. The method can also reduce the number of material charts needed in the Code and provides for the capability to extend the existing pressure charts to higher design temperatures. The new method is shown to contain a number of improvements over the traditional approach and is presently under consideration by appropriate ASME Code committees.

  12. Composite Pressure Vessel Variability in Geometry and Filament Winding Model

    NASA Technical Reports Server (NTRS)

    Green, Steven J.; Greene, Nathanael J.

    2012-01-01

    Composite pressure vessels (CPVs) are used in a variety of applications ranging from carbon dioxide canisters for paintball guns to life support and pressurant storage on the International Space Station. With widespread use, it is important to be able to evaluate the effect of variability on structural performance. Data analysis was completed on CPVs to determine the amount of variation that occurs among the same type of CPV, and a filament winding routine was developed to facilitate study of the effect of manufacturing variation on structural response.

  13. Statistical analysis of ionosphere parameters and atmospheric pressure correlations

    NASA Astrophysics Data System (ADS)

    Voloskov, Dmitriy; Bochkarev, Vladimir; Maslennikova, Yulia; Zagidullin, Bulat

    Ionosphere parameters such as Total electron content (TEC) and Doppler frequency shift characterize ionosphere influence on signals propagation, and therefore information about these parameters is important for radio communication tasks. Meteorological effects such as atmospheric pressure variations can influence on ionosphere parameters. This work is dedicated to analysis of correlations between meteorological and ionosphere parameters. NCEP/NCAR reanalysis meteorological maps, Jet Propulsion Laboratory (JPL) global TEC maps and data from Doppler phase goniometric complex “Spectr” were analysed. Data for 2009-2011 were investigated. Coherent oscillations with periods of 29-32 and 4 days were detected in atmospheric pressure and Doppler frequency shift variations.

  14. A Method to Control the Cushion Pressure of Oscillating SES

    NASA Astrophysics Data System (ADS)

    Senba, Hiromitsu; Matsuo, Hideo; Takahashi, Hidehiko; Yoshimoto, Shintarou; Matsuo, Kensuke; Kanazawa, Koji; Hiroe, Tetsuyuki; Fujiwara, Kazuhito

    A method is proposed to control the variation of cushion pressure of SES oscillating vertically. The peripheral nozzle is attached along the periphery and swings changing the discharge angle. The angle varies in accordance with the motion of the craft. A method is proposed to analyze the mechanism of this setup. The result is compared with experiments to show the agreement of the two results. It has been shown both theoretically and experimentally that the variation of the cushion pressure is effectively controlled adjusting the amplitude and the phase of the swinging motion of the nozzle.

  15. Impact of baseline systolic blood pressure on visit-to-visit blood pressure variability: the Kailuan study

    PubMed Central

    Wang, Anxin; Li, Zhifang; Yang, Yuling; Chen, Guojuan; Wang, Chunxue; Wu, Yuntao; Ruan, Chunyu; Liu, Yan; Wang, Yilong; Wu, Shouling

    2016-01-01

    Background To investigate the relationship between baseline systolic blood pressure (SBP) and visit-to-visit blood pressure variability in a general population. Methods This is a prospective longitudinal cohort study on cardiovascular risk factors and cardiovascular or cerebrovascular events. Study participants attended a face-to-face interview every 2 years. Blood pressure variability was defined using the standard deviation and coefficient of variation of all SBP values at baseline and follow-up visits. The coefficient of variation is the ratio of the standard deviation to the mean SBP. We used multivariate linear regression models to test the relationships between SBP and standard deviation, and between SBP and coefficient of variation. Results Approximately 43,360 participants (mean age: 48.2±11.5 years) were selected. In multivariate analysis, after adjustment for potential confounders, baseline SBPs <120 mmHg were inversely related to standard deviation (P<0.001) and coefficient of variation (P<0.001). In contrast, baseline SBPs ≥140 mmHg were significantly positively associated with standard deviation (P<0.001) and coefficient of variation (P<0.001). Baseline SBPs of 120–140 mmHg were associated with the lowest standard deviation and coefficient of variation. The associations between baseline SBP and standard deviation, and between SBP and coefficient of variation during follow-ups showed a U curve. Conclusion Both lower and higher baseline SBPs were associated with increased blood pressure variability. To control blood pressure variability, a good target SBP range for a general population might be 120–139 mmHg. PMID:27536123

  16. Blood pressure variability: a novel and important risk factor.

    PubMed

    Floras, John S

    2013-05-01

    Blood pressure is a continuous, not a static, variable. Individuals exhibiting similar clinic or home blood pressure can differ considerably with respect to their average day and nighttime values, beat-by-beat blood pressure variation during wakefulness and sleep, responses to mental and physical stimuli, and intersession and seasonal variation. There now is evidence that several such representations of blood pressure variability, if augmented, increase cardiovascular risk independent of the average of conventionally acquired blood pressure readings. As well, recent retrospective analyses of published trial data have concluded that antihypertensive drug classes differ in their effects on intersession blood pressure variability and associated risk of stroke. If the goal of the hypertension community is to optimize personalized cardiovascular risk assessment and to attenuate fully such risk, future efforts should be directed at determining which representation of blood pressure variability estimates individual cardiovascular risk best, establishing "normal" and "high- risk" variability distributions, testing the hypothesis that attenuating such variability specifically through drug or device therapy reduces cardiovascular risk more than blood pressure reduction per se, and integrating such data into clinical practice. PMID:23618505

  17. Pressure Ulcer Prevention

    PubMed Central

    2009-01-01

    Executive Summary In April 2008, the Medical Advisory Secretariat began an evidence-based review of the literature concerning pressure ulcers. Please visit the Medical Advisory Secretariat Web site, http://www.health.gov.on.ca/english/providers/program/mas/tech/tech_mn.html to review these titles that are currently available within the Pressure Ulcers series. Pressure ulcer prevention: an evidence based analysis The cost-effectiveness of prevention strategies for pressure ulcers in long-term care homes in Ontario: projections of the Ontario Pressure Ulcer Model (field evaluation) Management of chronic pressure ulcers: an evidence-based analysis (anticipated pubicstion date - mid-2009) Purpose A pressure ulcer, also known as a pressure sore, decubitus ulcer, or bedsore, is defined as a localized injury to the skin/and or underlying tissue occurring most often over a bony prominence and caused by pressure, shear, or friction, alone or in combination. (1) Those at risk for developing pressure ulcers include the elderly and critically ill as well as persons with neurological impairments and those who suffer conditions associated with immobility. Pressure ulcers are graded or staged with a 4-point classification system denoting severity. Stage I represents the beginnings of a pressure ulcer and stage IV, the severest grade, consists of full thickness tissue loss with exposed bone, tendon, and or muscle. (1) In a 2004 survey of Canadian health care settings, Woodbury and Houghton (2) estimated that the prevalence of pressure ulcers at a stage 1 or greater in Ontario ranged between 13.1% and 53% with nonacute health care settings having the highest prevalence rate (Table 1). Executive Summary Table 1: Prevalence of Pressure Ulcers* Setting Canadian Prevalence,% (95% CI) Ontario Prevalence,Range % (n) Acute care 25 (23.8–26.3) 23.9–29.7 (3418) Nonacute care† 30 (29.3–31.4) 30.0–53.3 (1165) Community care 15 (13.4–16.8) 13.2 (91) Mixed health care‡ 22 (20.9

  18. Pressure gradient torque in highly supersonic nonaxisymmetric accretion

    NASA Technical Reports Server (NTRS)

    Ho, Cheng; Taam, Ronald E.; Fryxell, Bruce A.; Matsuda, Takuya; Koide, Hiroshi

    1989-01-01

    The contribution of a pressure gradient torque to the angular momentum transfer rate in highly supersonic nonaxisymmetric accretion flows is considered. This study takes into account the contribution due to the pressure variation in the postaccretion-shock region which is significant for high Mach number accretion. For the case of accretion flow with Mach (infinity) of not less than 5, the overall accretion torque is shown to approach a constant value.

  19. FROG - Fingerprinting Genomic Variation Ontology.

    PubMed

    Abinaya, E; Narang, Pankaj; Bhardwaj, Anshu

    2015-01-01

    Genetic variations play a crucial role in differential phenotypic outcomes. Given the complexity in establishing this correlation and the enormous data available today, it is imperative to design machine-readable, efficient methods to store, label, search and analyze this data. A semantic approach, FROG: "FingeRprinting Ontology of Genomic variations" is implemented to label variation data, based on its location, function and interactions. FROG has six levels to describe the variation annotation, namely, chromosome, DNA, RNA, protein, variations and interactions. Each level is a conceptual aggregation of logically connected attributes each of which comprises of various properties for the variant. For example, in chromosome level, one of the attributes is location of variation and which has two properties, allosomes or autosomes. Another attribute is variation kind which has four properties, namely, indel, deletion, insertion, substitution. Likewise, there are 48 attributes and 278 properties to capture the variation annotation across six levels. Each property is then assigned a bit score which in turn leads to generation of a binary fingerprint based on the combination of these properties (mostly taken from existing variation ontologies). FROG is a novel and unique method designed for the purpose of labeling the entire variation data generated till date for efficient storage, search and analysis. A web-based platform is designed as a test case for users to navigate sample datasets and generate fingerprints. The platform is available at http://ab-openlab.csir.res.in/frog. PMID:26244889

  20. Sounding experiments of high pressure gas discharge

    SciTech Connect

    Biele, Joachim K.

    1998-07-10

    A high pressure discharge experiment (200 MPa, 5{center_dot}10{sup 21} molecules/cm{sup 3}, 3000 K) has been set up to study electrically induced shock waves. The apparatus consists of the combustion chamber (4.2 cm{sup 3}) to produce high pressure gas by burning solid propellant grains to fill the electrical pump chamber (2.5 cm{sup 3}) containing an insulated coaxial electrode. Electrical pump energy up to 7.8 kJ at 10 kV, which is roughly three times of the gas energy in the pump chamber, was delivered by a capacitor bank. From the current-voltage relationship the discharge develops at rapidly decreasing voltage. Pressure at the combustion chamber indicating significant underpressure as well as overpressure peaks is followed by an increase of static pressure level. These data are not yet completely understood. However, Lorentz forces are believed to generate pinching with subsequent pinch heating, resulting in fast pressure variations to be propagated as rarefaction and shock waves, respectively. Utilizing pure axisymmetric electrode initiation rather than often used exploding wire technology in the pump chamber, repeatable experiments were achieved.

  1. Pressure ulcers: Back to the basics

    PubMed Central

    Agrawal, Karoon; Chauhan, Neha

    2012-01-01

    Pressure ulcer in an otherwise sick patient is a matter of concern for the care givers as well as the medical personnel. A lot has been done to understand the disease process. So much so that USA and European countries have established advisory panels in their respective continents. Since the establishment of these organizations, the understanding of the pressure ulcer has improved significantly. The authors feel that the well documented and well publicized definition of pressure ulcer is somewhat lacking in the correct description of the disease process. Hence, a modified definition has been presented. This disease is here to stay. In the process of managing these ulcers the basic pathology needs to be understood well. Pressure ischemia is the main reason behind the occurrence of ulceration. Different extrinsic and intrinsic factors have been described in detail with review of literature. There are a large number of risk factors causing ulceration. The risk assessment scales have eluded the surgical literature and mostly remained in nursing books and websites. These scales have been reproduced for completion of the basics on decubitus ulcer. The classification of the pressure sores has been given in a comparative form to elucidate that most of the classifications are the same except for minor variations. The management of these ulcers is ever evolving but the age old saying of “prevention is better than cure” suits this condition the most. PMID:23162223

  2. The influence of task variation on manifestation of fatigue is ambiguous - a literature review.

    PubMed

    Luger, Tessy; Bosch, Tim; Veeger, Dirkjan; de Looze, Michiel

    2014-01-01

    Task variation has been proposed to reduce shoulder fatigue resulting from repetitive hand-arm tasks. This review analyses the effect of task variation, both 'temporal (i.e. change of work-rest ratio)' and 'activity (i.e. job rotation)' variation, on physiological responses, endurance time (ET) and subjective feelings. Pubmed was searched and complemented with references from selected articles, resulting in 17 articles. Temporal variation had some positive effects on the objective parameters, as blood pressure decreased and ET increased, and on the subjective feelings, as perceived discomfort decreased. The observed findings of activity variation showed both positive and negative effects of increased activity variation, while hardly any effects were found on electromyography manifestations of fatigue. In conclusion, the evidence for positive effects of increasing the level of variation is scarce. The number of studies on variation is limited, while in most studies the findings were not controlled for the amount or intensity of work. PMID:24552472

  3. Internal pressure sensor

    DOEpatents

    Dowalo, James A [Blackfoot, ID

    2010-03-16

    A pressure sensor for sensing changes in pressure in an enclosed vessel may include a first chamber having at least one expandable section therein that allows that first chamber to change in length. A reference member mounted within the first chamber moves as a result of changes in length of the first chamber. A second chamber having an expandable section therein allows the second chamber to change in length in response to changes in pressure in the enclosed vessel. The second chamber is operatively associated with the first chamber so that changes in length of the second chamber result in changes in length of the first chamber. A sensor operatively associated with the reference member detects changes in position of the reference member. Changes in position of the reference member are related to changes in pressure in the enclosed vessel.

  4. Capacitance pressure sensor

    DOEpatents

    Eaton, William P.; Staple, Bevan D.; Smith, James H.

    2000-01-01

    A microelectromechanical (MEM) capacitance pressure sensor integrated with electronic circuitry on a common substrate and a method for forming such a device are disclosed. The MEM capacitance pressure sensor includes a capacitance pressure sensor formed at least partially in a cavity etched below the surface of a silicon substrate and adjacent circuitry (CMOS, BiCMOS, or bipolar circuitry) formed on the substrate. By forming the capacitance pressure sensor in the cavity, the substrate can be planarized (e.g. by chemical-mechanical polishing) so that a standard set of integrated circuit processing steps can be used to form the electronic circuitry (e.g. using an aluminum or aluminum-alloy interconnect metallization).

  5. Pressurized Vessel Slurry Pumping

    SciTech Connect

    Pound, C.R.

    2001-09-17

    This report summarizes testing of an alternate ''pressurized vessel slurry pumping'' apparatus. The principle is similar to rural domestic water systems and ''acid eggs'' used in chemical laboratories in that material is extruded by displacement with compressed air.

  6. Blood pressure check (image)

    MedlinePlus

    ... more often referred to as a blood pressure cuff. The cuff is wrapped around your upper arm and inflated ... flow of blood in your artery. As the cuff is slowly deflated, your doctor uses a stethoscope ...

  7. On Time Performance Pressure

    NASA Technical Reports Server (NTRS)

    Connell, Linda; Wichner, David; Jakey, Abegael

    2013-01-01

    Within many operations, the pressures for on-time performance are high. Each month, on-time statistics are reported to the Department of Transportation and made public. There is a natural tendency for employees under pressure to do their best to meet these objectives. As a result, pressure to get the job done within the allotted time may cause personnel to deviate from procedures and policies. Additionally, inadequate or unavailable resources may drive employees to work around standard processes that are seen as barriers. However, bypassing practices to enable on-time performance may affect more than the statistics. ASRS reports often highlight on-time performance pressures which may result in impact across all workgroups in an attempt to achieve on-time performance. Reporters often provide in-depth insights into their experiences which can be used by industry to identify and focus on the implementation of systemic fixes.

  8. High Blood Pressure

    MedlinePlus

    ... Division of Geriatrics and Clinical Gerontology Division of Neuroscience FAQs Funding Opportunities Intramural Research Program Office of ... to major health problems. Make a point of learning what blood pressure should be. And, remember: High ...

  9. Blood Pressure Checker

    NASA Technical Reports Server (NTRS)

    1979-01-01

    An estimated 30 million people in the United States have high blood pressure, or hypertension. But a great many of them are unaware of it because hypertension, in its initial stages, displays no symptoms. Thus, the simply-operated blood pressure checking devices now widely located in public places are useful health aids. The one pictured above, called -Medimax 30, is a direct spinoff from NASA technology developed to monitor astronauts in space. For manned space flights, NASA wanted a compact, highly-reliable, extremely accurate method of checking astronauts' blood pressure without the need for a physician's interpretive skill. NASA's Johnson Space Center and Technology, Inc., a contractor, developed an electronic sound processor that automatically analyzes blood flow sounds to get both systolic (contracting arteries) and diastolic (expanding arteries) blood pressure measurements. NASA granted a patent license for this technology to Advanced Life Sciences, Inc., New York City, manufacturers of Medimax 30.

  10. Osteomyelitis beneath pressure sores

    SciTech Connect

    Sugarman, B.; Hawes, S.; Musher, D.M.; Klima, M.; Young, E.J.; Pircher, F.

    1983-04-01

    Twenty-eight pressure sores were evaluated prospectively. Osteomyelitis was reported histologically in nine of 28 bones and pressure-related changes were reported in 14 bones. Roentgenograms suggested the presence of osteomyelitis in four instances of histologically proved osteomyelitis. Technetium Tc 99m medronate bone scans were highly sensitive, showing increased uptake in all cases of osteomyelitis; however, increased uptake also occurred commonly in uninfected bones due to pressure-related changes or other noninfectious causes. Cultures of bone biopsy samples usually disclosed anaerobic bacteria, gram-negative bacilli, or both. The diagnosis of osteomyelitis must be considered if a pressure sore does not respond to local therapy. If the technetium Tc 99m medronate uptake is increased in the involved area, or roentgenographic findings are abnormal, the diagnosis can only be made with certainty by histologic examination of bone. Antibacterial treatment should be selected based on the results of bone culture.

  11. Space shuttle: Stability and control effectiveness at high and low angles of attack and effects of variations in engine shround, fin, and drag petal configurations for the Boeing 0.008899-scale pressure-fed ballistic recoverable booster, model 979-160

    NASA Technical Reports Server (NTRS)

    Hanson, R. L.; Obrien, R. G.; Oiye, M. Y.; Vanderleest, S.

    1972-01-01

    Experimental aerodynamic investigations were carried out in the Boeing transonic and supersonic wind tunnels on a 0.008899-scale model of a proposed pressure-fed ballistic recoverable booster (BRB) configuration. The purpose of the test program was to determine the stability and control effectiveness of the basic configuration at high and low angles of attack, and to conduct parametric studies of various engine shroud, fin, and drag petal configurations. Six-component force data and base pressure data were obtained over a Mach number range of 0.35 to 4.0 at angles of attack of -5 to 25 and 55 to 85 at zero degrees sideslip and over a sideslip range of -10 to +10 at angles of attack ranging from -10 to 72.5. Two-component force data were also obtained with a fin balance on selected runs.

  12. Pressure multiplying dispenser

    DOEpatents

    DeFord, Henry S.; Moss, Owen R.

    1986-01-01

    A pressure multiplying dispenser for delivering fluid, preferably as a spray to the atmosphere, from a source of fluid, preferably a spray bottle, is described. The dispenser includes in combination a hollow cylindrical member, a nozzle delivery tube within the cylindrical member and a hollow actuator piston slideable within the cylindrical member which acts to multiply the pressure of a squeeze applied to the spray bottle.

  13. Fluid pressure balanced seal

    NASA Technical Reports Server (NTRS)

    Marsh, H. W. (Inventor)

    1966-01-01

    A seal which increases in effectiveness with increasing pressure is presented. The seal's functional capability throughout both static and dynamic operation makes it particularly useful for sealing ball valve ports. Other features of the seal include the ability to seal two opposed surfaces simultaneously, tolerance of small misalignments, tolerance of wide temperature ranges, ability to maintain positive sealing contact under conditions of internal or external pressurization, and ability to conform to slight irregularities in seal or surface contours.

  14. Radial pressure flange seal

    DOEpatents

    Batzer, T.H.; Call, W.R.

    1989-01-24

    This invention provides an all metal seal for vacuum or pressure vessels or systems. This invention does not use gaskets. The invention uses a flange which fits into a matching groove. Fluid pressure is applied in a chamber in the flange causing at least one of the flange walls to radially press against a side of the groove creating the seal between the flange wall and the groove side. 5 figs.

  15. Radial pressure flange seal

    DOEpatents

    Batzer, Thomas H.; Call, Wayne R.

    1989-01-01

    This invention provides an all metal seal for vacuum or pressure vessels or systems. This invention does not use gaskets. The invention uses a flange which fits into a matching groove. Fluid pressure is applied in a chamber in the flange causing at least one of the flange walls to radially press against a side of the groove creating the seal between the flange wall and the groove side.

  16. Slope instability caused by small variations in hydraulic conductivity

    USGS Publications Warehouse

    Reid, M.E.

    1997-01-01

    Variations in hydraulic conductivity can greatly modify hillslope ground-water flow fields, effective-stress fields, and slope stability. In materials with uniform texture, hydraulic conductivities can vary over one to two orders of magnitude, yet small variations can be difficult to determine. The destabilizing effects caused by small (one order of magnitude or less) hydraulic conductivity variations using ground-water flow modeling, finite-element deformation analysis, and limit-equilibrium analysis are examined here. Low hydraulic conductivity materials that impede downslope ground-water flow can create unstable areas with locally elevated pore-water pressures. The destabilizing effects of small hydraulic heterogeneities can be as great as those induced by typical variations in the frictional strength (approximately 4??-8??) of texturally similar materials. Common "worst-case" assumptions about ground-water flow, such as a completely saturated "hydrostatic" pore-pressure distribution, do not account for locally elevated pore-water pressures and may not provide a conservative slope stability analysis. In site characterization, special attention should be paid to any materials that might impede downslope ground-water flow and create unstable regions.

  17. Effects of Zonal Wind on Stratospheric Ozone Variations over Nigeria

    NASA Astrophysics Data System (ADS)

    Chidinma Okoro, Eucharia,

    2016-07-01

    The effects of zonal wind on stratospheric ozone variation over Nigeria have been studied. The areas covered in this study include; Maiduguri, Ikeja, Port-Harcourt, Calabar, Makurdi, Ilorin, Akure, Yola, Minna, Jos, Kano and Enugu in Nigeria, from 1986 to 2008. Zonal wind was computed from the iso-velocity map employing MATLAB software. The mean monthly variations of AAM and LOD at pressure levels of 20, 30 and 50 mb in the atmosphere depict a trend of maximum amplitude between April and September, and minimum amplitude between December and March. The trend observed in seasonal variation of O3 column data in the low latitude had maximum amount from May through August and minimum values from December through February. The mean monthly maximum O3 concentrations was found to be 284.70 Du (Kano) occurring in May 1989 while, an average monthly minimum O3 concentration was found to be 235.60 Du (Port-Harcourt and Calabar) occurring in January 1998. It has been established in this study that, the variation in atmospheric angular momentum (AAM) caused by variation of the universal time or length of day (LOD) transfer ozone (O3) by means of zonal wind from the upper troposphere to the lower stratosphere in the stations understudy. The strong effect of the pressure levels of the atmosphere on O3 variation could be attributed to its effect on the AAM and LOD. Variation in the LOD is significant in the tropics, suggesting that, the effects of the extra-tropical suction pump (ETSP) action is not the only driver responsible for O3 transportation from the tropics to extra-tropical zones. Consequently, these findings lead to a deduction that weather pattern alteration observed due to these changes could lead to climate change. Keywords: ozone variations; dynamical processes; harmattan wind; ETSP; and climatic variability

  18. Citrullinemia: phenotypic variations.

    PubMed

    Whelan, D T; Brusso, T; Spate, M

    1976-06-01

    An 18-month-old female infant was found to have citrullinemia on routine plasma screening by the Scriver Method at 5 days of age. At 10 days of age, plasma citrulline concentration was 0.704mumol/ml (normal, 0.010 to 0.030mumol/ml) and has remained 60 to 80 times higher than normal. Urine citrulline concentration was markedly elevated. Hyperammonemia occurred at 1 month of age. The serum ammonia concentration was 473mug/100 ml (normal, 50 to 250 mug/100 ml) and rose to 770mug/100 ml at 4 months of age. Dietary protein was restricted to 1.6 gm/kg/day. Without further change in protein intake, the serum ammonia concentration decreased to 280mug/100 ml and, since then, it has returned to normal. The addition of three synthetic L-amino acids was required for a short time during dietary therapy. At 10 months of age, the infant was given a normal diet. At 18 months of age, her physical and mental development is normal. Activity of argininosuccinic acid synthetase measured in skin fibroblasts was 0.0037mumol of radioactive carbon dioxide per milligram of protein per hour. To demonstrate heterozygosity, fasting plasma citrulline concentrations were measured in five members of the family. Comparison of findings in this patient with those reported in the literature suggests phenotypical variation of the disease, probably due to genetic heterogeneity. PMID:934749

  19. Variation of ENSO teleconnections

    NASA Astrophysics Data System (ADS)

    Wittenberg, A. T.

    2012-12-01

    The El Niño/Southern Oscillation (ENSO) drives remote teleconnection patterns that affect weather and climate worldwide. These teleconnections have in turn been used to reconstruct the past variability of ENSO, using sparse observations and ENSO-sensitive proxy records from around the globe. This study examines intrinsic and forced variations of ENSO teleconnections, using simulations from a suite of global coupled GCMs that mimic the observed ENSO teleconnections rather well. Records of various lengths are extracted from a long control run of the GFDL CM2.1 coupled GCM, and anomalies of global surface temperature, rainfall, and 200 hPa heights are regressed onto standard ENSO indices. The resulting teleconnection distributions are characterized in terms of their dependence on record length, season, and ENSO event type, and are then used to assess the detectability of teleconnection changes arising from changes in external forcings or model formulation. The results clarify the uncertainties that arise from calibrating historical and paleoclimate reconstructions to sparse observational records, and shed light on future climate risks tied to ENSO.

  20. What Is High Blood Pressure?

    MedlinePlus

    ... Blood Pressure Tools & Resources Stroke More What is High Blood Pressure? Updated:Aug 26,2016 High blood pressure, also ... content was last reviewed on 08/04/2014. High Blood Pressure • Home • About High Blood Pressure (HBP) Introduction What ...

  1. Pressure sensing using a completely flexible organic transistor.

    PubMed

    Manunza, I; Bonfiglio, A

    2007-06-15

    In this paper, we report on pressure sensors based on completely flexible organic thin film transistors (OTFTs). A flexible and transparent plastic foil (Mylar) is employed both as substrate and gate dielectric. Gold source and drain electrodes are patterned on the upper side of the foil while the gate electrode lies on the opposite side; a vacuum-sublimed pentacene film is used as active layer. The pressure dependence of the output current has been investigated by applying to the gate side of the device a mechanical stimulus by means of a pressurized airflow. Experimental results show a reversible dependence of the current on the pressure. The data analysis suggests that the current variations are due to pressure-induced variations of mobility, threshold voltage and possibly contact resistance. The drain current variation is reproducible, linear and reversible even though it displays a hysteresis. Moreover, the sensor responds very fast to the mechanical stimulus (i.e. within tens-hundreds of milliseconds) but the time required to reach the steady state is much higher (tens-hundreds of seconds). Electrical characteristics with and without applied pressure have been carried out in air without any extra ad hoc read-out circuit or equipment. The reported devices show potential advantages of flexibility of the structure, low cost and versatility of the device structure for sensor technologies. Many innovative and attractive applications as wearable electronics, e-textiles, e-skin for robots can be considered. PMID:17344042

  2. ECN Pressure Test

    SciTech Connect

    Dixon, K.; /Fermilab

    1991-07-18

    This note describes: the rationale for the test pressure of the inner ECN cryostat vessel, the equipment to be used in this test, the test procedure, the status of the vessel prior to the test, the actual test results, and a schematic diagram of the testing set up and the pressure testing permit. The test, performed in the evening of July 17, 1991, was a major success. Based on a neglible pressure drop indicated on the pressure gages (1/4 psi), the vessel appeared to be structurally sound throughout the duration of the test (approx. 1.5 hrs.). No pressure increases were observed on the indicators looking at the beam tube bellows volumes. There was no indication of bubbles form the soap test on the welds and most of the fittings that were checked. There were some slight deviations in the actual procedure used. The UO filter was removed after the vessel had bled down to about 18 psig in order to speed up that aspect of the test. The rationale was that the higher velocity gas had already passed through at the higher pressures and there was no visible traces of the black uo particles. The rate of 4 psi/10 minutes seemed incredibly slow and often that time was reduced to just over half that rate. The testing personnel was allowed to stay in the pit throughout the duration of the test; this was a slight relaxation of the rules.

  3. Fluctuating shells under pressure

    PubMed Central

    Paulose, Jayson; Vliegenthart, Gerard A.; Gompper, Gerhard; Nelson, David R.

    2012-01-01

    Thermal fluctuations strongly modify the large length-scale elastic behavior of cross-linked membranes, giving rise to scale-dependent elastic moduli. Whereas thermal effects in flat membranes are well understood, many natural and artificial microstructures are modeled as thin elastic shells. Shells are distinguished from flat membranes by their nonzero curvature, which provides a size-dependent coupling between the in-plane stretching modes and the out-of-plane undulations. In addition, a shell can support a pressure difference between its interior and its exterior. Little is known about the effect of thermal fluctuations on the elastic properties of shells. Here, we study the statistical mechanics of shape fluctuations in a pressurized spherical shell, using perturbation theory and Monte Carlo computer simulations, explicitly including the effects of curvature and an inward pressure. We predict novel properties of fluctuating thin shells under point indentations and pressure-induced deformations. The contribution due to thermal fluctuations increases with increasing ratio of shell radius to thickness and dominates the response when the product of this ratio and the thermal energy becomes large compared with the bending rigidity of the shell. Thermal effects are enhanced when a large uniform inward pressure acts on the shell and diverge as this pressure approaches the classical buckling transition of the shell. Our results are relevant for the elasticity and osmotic collapse of microcapsules. PMID:23150558

  4. Pressure Core Characterization

    NASA Astrophysics Data System (ADS)

    Santamarina, J. C.

    2014-12-01

    Natural gas hydrates form under high fluid pressure and low temperature, and are found in permafrost, deep lakes or ocean sediments. Hydrate dissociation by depressurization and/or heating is accompanied by a multifold hydrate volume expansion and host sediments with low permeability experience massive destructuration. Proper characterization requires coring, recovery, manipulation and testing under P-T conditions within the stability field. Pressure core technology allows for the reliable characterization of hydrate bearing sediments within the stability field in order to address scientific and engineering needs, including the measurement of parameters used in hydro-thermo-mechanical analyses, and the monitoring of hydrate dissociation under controlled pressure, temperature, effective stress and chemical conditions. Inherent sampling effects remain and need to be addressed in test protocols and data interpretation. Pressure core technology has been deployed to study hydrate bearing sediments at several locations around the world. In addition to pressure core testing, a comprehensive characterization program should include sediment analysis, testing of reconstituted specimens (with and without synthetic hydrate), and in situ testing. Pressure core characterization technology can be used to study other gas-charged formations such as deep sea sediments, coal bed methane and gas shales.

  5. Influence of pressure on pyrolysis of black liquor: 2. Char yields and component release.

    PubMed

    Whitty, Kevin; Kullberg, Mika; Sorvari, Vesa; Backman, Rainer; Hupa, Mikko

    2008-02-01

    This is the second in a series of papers concerning the behavior of black liquor during pyrolysis at elevated pressures. Two industrial black liquors were pyrolyzed under pressurized conditions in two laboratory-scale devices, a pressurized single-particle reactor and a pressurized grid heater. Temperatures ranging between 650 and 1100 degrees C and pressures in the range 1-20 bar were studied. Char yields were calculated and based on analysis of some of the chars the fate of carbon, sodium, potassium and sulfur was determined as a function of pyrolysis pressure. At temperatures below 800 degrees C little variation in char yield was observed at different pressures. At higher temperatures char yield increased with pressure due to slower decomposition of sodium carbonate. For the same reason, sodium release decreased with pressure. Sulfur release, however, increased with pressure primarily because there was less opportunity for its capture in the less-swollen chars. PMID:17349787

  6. Tunneling spectroscopy of Al/AlO{sub x}/Pb subjected to hydrostatic pressure

    SciTech Connect

    Zhu, Jun; Hou, Xing-Yuan; Guan, Tong; Zhang, Qin-Tong; Li, Yong-Qing; Han, Xiu-Feng; Li, Chun-Hong; Ren, Cong; Yang, Zheng-Xin; Zhang, Jin; Shan, Lei; Chen, Gen-Fu

    2015-05-18

    We develop an experimental tool to investigate high-pressure electronic density of state by combining electron tunneling spectroscopy measurements with high-pressure technique. It is demonstrated that tunneling spectroscopy measurement on Al/AlO{sub x}/Pb junction is systematically subjected to hydrostatic pressure up to 2.2 GPa. Under such high pressure, the normal state junction resistance is sensitive to the applied pressure, reflecting the variation of band structure of the barrier material upon pressures. In superconducting state, the pressure dependence of the energy gap Δ{sub 0}, the gap ratio 2Δ{sub 0}/k{sub B}T{sub c}, and the phonon spectral energy is extracted and compared with those obtained in the limited pressure range. Our experimental results show the accessibility and validity of high pressure tunneling spectroscopy, offering wealthy information about high pressure superconductivity.

  7. Diurnal variations in blood flow at optic nerve head and choroid in healthy eyes: diurnal variations in blood flow.

    PubMed

    Iwase, Takeshi; Yamamoto, Kentaro; Ra, Eimei; Murotani, Kenta; Matsui, Shigeyuki; Terasaki, Hiroko

    2015-02-01

    To investigate the diurnal variations of the ocular blood flow in healthy eyes using laser speckle flowgraphy (LSFG), and to determine the relationship of the diurnal variations between the ocular blood flow and other ocular parameters.This prospective cross-sectional study was conducted at Nagoya University Hospital. We studied 13 healthy volunteers whose mean age was 33.5 ± 7.6 years. The mean blur rate (MBR), expressing the relative blood flow, on the optic nerve head (ONH) and choroidal blood flow was determined by LSFG (LSFG-NAVI) every 3 hours from 6:00 to 24:00 hours. The intraocular pressure (IOP), choroidal thickness measured by enhanced depth imaging optical coherence tomography, systolic (SBP) and diastolic (DBP) blood pressure, and heart rate (HR) in the brachial artery were also recorded. We evaluated the diurnal variations of the parameters and compared the MBR to the other parameters using a linear mixed model.The diurnal variations of the MBR on the ONH varied significantly with a trough at 9:00 hours and a peak at 24:00 hours (P < 0.001, linear mixed model). The MBR of choroid also had significant diurnal variations with a trough at 15:00 hours and a peak at 18:00 hours (P = 0.001). The IOP (P < 0.001), choroidal thickness (P < 0.001), SBP (P = 0.005), DBP (P = 0.001), and HR (P < 0.001) also had significant diurnal variations. Although the diurnal variation of the MBR on the ONH was different from the other parameters, that on the choroid was significantly and positively correlated with the DBP (P = 0.002), mean arterial pressure (P = 0.023), and mean ocular perfusion pressure (P = 0.047).We found significant diurnal variations in the ONH and choroidal blood flow. Although the ONH blood flow had its own diurnal variation because of strong autoregulation, the choroidal blood flow was more likely affected by systemic circulatory factors because of poor autoregulation. PMID:25674750

  8. Effect of temperature and pressure on the dynamics of nanoconfined propane

    SciTech Connect

    Gautam, Siddharth Liu, Tingting Welch, Susan; Cole, David; Rother, Gernot; Jalarvo, Niina; Mamontov, Eugene

    2014-04-24

    We report the effect of temperature and pressure on the dynamical properties of propane confined in nanoporous silica aerogel studied using quasielastic neutron scattering (QENS). Our results demonstrate that the effect of a change in the pressure dominates over the effect of temperature variation on the dynamics of propane nano-confined in silica aerogel. At low pressures, most of the propane molecules are strongly bound to the pore walls, only a small fraction is mobile. As the pressure is increased, the fraction of mobile molecules increases. A change in the mechanism of motion, from continuous diffusion at low pressures to jump diffusion at higher pressures has also been observed.

  9. Availability of high-pressure safety injection system in PWRs

    SciTech Connect

    Sun, Y.H.; Fresco, A.; Papazoglou, I.A.

    1983-01-01

    This paper presents an evaluation of the impact of typical variations in configuration of the design of the High Pressure Injection (HPSI) System on system unavailability. The HPSI systems in seventeen nuclear power plants were reviewed for variations in design, systems operation, testing and maintenance policies, and possible sources for common cause failures. The power plants reviewed include PWRs with two, three and four loop Reactor Coolant Systems and cover all three PWR vendors. As a result of this effort, the following five representative configurations (along with some variations) were identified and their unavailability to initiate injection was estimated.

  10. A Resonant Pressure Microsensor Capable of Self-Temperature Compensation

    PubMed Central

    Li, Yinan; Wang, Junbo; Luo, Zhenyu; Chen, Deyong; Chen, Jian

    2015-01-01

    Resonant pressure microsensors are widely used in the fields of aerospace exploration and atmospheric pressure monitoring due to their advantages of quasi-digital output and long-term stability, which, however, requires the use of additional temperature sensors for temperature compensation. This paper presents a resonant pressure microsensor capable of self-temperature compensation without the need for additional temperature sensors. Two doubly-clamped “H” type resonant beams were arranged on the pressure diaphragm, which functions as a differential output in response to pressure changes. Based on calibration of a group of intrinsic resonant frequencies at different pressure and temperature values, the functions with inputs of two resonant frequencies and outputs of temperature and pressure under measurement were obtained and thus the disturbance of temperature variations on resonant frequency shifts was properly addressed. Before compensation, the maximal errors of the measured pressure values were over 1.5% while after compensation, the errors were less than 0.01% of the full pressure scale (temperature range of −40 °C to 70 °C and pressure range of 50 kPa to 110 kPa). PMID:25938197

  11. Seasonal variations in Soudan 2.

    SciTech Connect

    Goodman, M. C.; Soudan 2 Collaboration

    1999-06-23

    Seasonal Variations in an underground detector may be a signature for Dark Matter. The Soudan 2 detector searches for nucleon decay and atmospheric neutrinos. The trigger rate is about 0.5 Hertz. It is dominated by approximately equal numbers of atmospheric muons and low level radioactivityy. The muon rate has a seasonal variation of {+-}2%, which is consistent with a similar effect at MACRO. The MACRO effect has been correlated with temperature in the upper atmosphere. Our trigger rate has a seasonal variation of {+-}15% which we believe is due to radon in the mine, and variations in air flow with outside temperature.

  12. Seasonal variations in Pluto's atmospheric tides

    NASA Astrophysics Data System (ADS)

    French, Richard G.; Toigo, Anthony D.; Gierasch, Peter J.; Hansen, Candice J.; Young, Leslie A.; Sicardy, Bruno; Dias-Oliveira, Alex; Guzewich, Scott D.

    2015-01-01

    Pluto's tenuous atmosphere exhibits remarkable seasonal change as a result of the planet's substantial obliquity and highly eccentric orbit. Over the past two decades, occultations have revealed that the atmospheric pressure on Pluto has increased substantially, perhaps by a factor as large as 2 to 4, as the planet has moved from equinox towards solstice conditions. These data have also shown variations in the strength of the dynamical activity in the atmosphere, as revealed by the varying abundance and amplitude of spikes in the occultation light curves resulting from refractive focussing by atmospheric waves. Toigo et al. (Toigo et al. [2010]. Icarus, 208, 402-411) explored the possibility that these waves are caused by solar-induced sublimation and diurnal deposition from N2 frost patches, driven by weak vertical winds resulting from the rising and sinking gas as it is released from or deposited onto the surface. Here, we extend this model to account explicitly for seasonal variations in average insolation and for the significant damping of vertical wave propagation by kinematic viscosity and thermal diffusivity (Hubbard et al. [2009]. Icarus, 204, 284-289). Damping is extremely effective in suppressing vertical propagation of waves with vertical wavelengths of a few kilometers or less, and the dominant surviving tidal modes have characteristic vertical wavelengths λ ∼ 10-13 km . We estimate the expected strength and regional characteristics of atmospheric tides over the course of Pluto's orbit for a variety of assumed spatial distributions of surface frost and atmospheric surface pressure. We compute the predicted strength of tide-induced wave activity based on the actual frost distribution observed on Pluto from Hubble Space Telescope (HST) observations (Stern et al. [1997]. Astron. J., 113, 827; Buie et al. [2010]. Astron. J., 139, 1128-1143), and compare the results to calculations for volatile transport models of Young (Young [2013]. Astrophys. J., 766

  13. Explorations in Regional Variation: A Variational Pragmatic Perspective

    ERIC Educational Resources Information Center

    Barron, Anne

    2015-01-01

    The present article introduces the Special Issue entitled "A Variational Pragmatic Approach to Regional Variation in Language," a collection of papers which celebrates the work of Klaus P. Schneider (Rheinische Friedrich-Wilhelms-Universität Bonn, Germany) on the occasion of his 60th birthday.

  14. Inexpensive Pressure-Relief Valve

    NASA Technical Reports Server (NTRS)

    Theordore, E. A.

    1985-01-01

    Simple device vents excess low-pressure gas. Inexpensive pressure relief valve built from polyvinylchloride pipe. Valve suitable for low pressure-- 25 to 50 cm of mercury-- and flow rates up to 14 m3/min.

  15. Blood pressure monitors for home

    MedlinePlus

    ... on its own. The screen will show a digital readout of your systolic and diastolic blood pressure. After showing your blood pressure, the cuff will deflate on its own. ... again. A digital blood pressure monitor will not be as accurate ...

  16. Prevention of High Blood Pressure

    MedlinePlus

    ... page from the NHLBI on Twitter. Prevention of High Blood Pressure Healthy lifestyle habits, proper use of medicines, and ... prevent high blood pressure or its complications. Preventing High Blood Pressure Onset Healthy lifestyle habits can help prevent high ...

  17. High Blood Pressure in Pregnancy

    MedlinePlus

    ... health of you and your baby. Treatments for high blood pressure in pregnancy may include close monitoring of the baby, lifestyle ... Some pregnant women with high blood pressure develop preeclampsia. It's a sudden increase in blood pressure after ...

  18. Reotemp Pressure Indicator Local Pressure Indication to Monitor the SCHE Supply Bottle Pressure

    SciTech Connect

    VAN KATWIJK, C.

    1999-07-01

    These 0-3000 psig range pressure indicators are located in the SCHe helium supply lines at the pressure bottles and upstream of the PRV. These accident monitoring local pressure indicators monitor the SCHe supply bottle pressure. There is one pressure indicator for each SCHe supply (4).

  19. Cryogenic High Pressure Sensor Module

    NASA Technical Reports Server (NTRS)

    Chapman, John J. (Inventor); Shams, Qamar A. (Inventor); Powers, William T. (Inventor)

    1999-01-01

    A pressure sensor is provided for cryogenic, high pressure applications. A highly doped silicon piezoresistive pressure sensor is bonded to a silicon substrate in an absolute pressure sensing configuration. The absolute pressure sensor is bonded to an aluminum nitride substrate. Aluminum nitride has appropriate coefficient of thermal expansion for use with highly doped silicon at cryogenic temperatures. A group of sensors, either two sensors on two substrates or four sensors on a single substrate are packaged in a pressure vessel.

  20. Downhole pressure attenuation apparatus

    SciTech Connect

    Ricles, T.D.; Barton, J.A.

    1992-02-18

    This patent describes a process for preventing damage to tool strings and other downhole equipment in a well caused by pressures produced during detonation of one or more downhole explosive devices. It comprises adding to a tool string at least one pressure attenuating apparatus for attenuating the peak pressure wave and quasi-static pressure pulse produced by the explosive devices, the pressure attenuating apparatus including an initially closed relief vent including tubing means supporting a plurality of charge port assemblies each including an explosive filled shaped charge and a prestressed disc, the shaped charges interconnected by a detonating cord, the amount of explosive in each shaped charge being sufficient to rupture its associated disc without damaging surrounding tubular bodies in the well, and a vent chamber defined by the tubing means and providing a liquid free volume, and opening the relief vent substantially contemporaneously with downhole explosive device detonation by detonating the shaped charges to rupture the discs of the charge port assemblies.

  1. Flow compensating pressure regulator

    NASA Technical Reports Server (NTRS)

    Baehr, E. F. (Inventor)

    1978-01-01

    An apparatus for regulating pressure of treatment fluid during ophthalmic procedures is described. Flow sensing and pressure regulating diaphragms are used to modulate a flow control valve. The pressure regulating diaphragm is connected to the flow control valve to urge the valve to an open position due to pressure being applied to the diaphragm by bias means such as a spring. The flow sensing diaphragm is mechanically connected to the flow control valve and urges it to an opened position because of the differential pressure on the diaphragm generated by a flow of incoming treatment fluid through an orifice in the diaphragm. A bypass connection with a variable restriction is connected in parallel relationship to the orifice to provide for adjusting the sensitivity of the flow sensing diaphragm. A multiple lever linkage system is utilized between the center of the second diaphragm and the flow control valve to multiply the force applied to the valve by the other diaphragm and reverse the direction of the force.

  2. Cavitation pressure in water

    NASA Astrophysics Data System (ADS)

    Herbert, Eric; Balibar, Sébastien; Caupin, Frédéric

    2006-10-01

    We investigate the limiting mechanical tension (negative pressure) that liquid water can sustain before cavitation occurs. The temperature dependence of this quantity is of special interest for water, where it can be used as a probe of a postulated anomaly of its equation of state. After a brief review of previous experiments on cavitation, we describe our method which consists in focusing a high amplitude sound wave in the bulk liquid, away from any walls. We obtain highly reproducible results, allowing us to study in detail the statistics of cavitation, and to give an accurate definition of the cavitation threshold. Two independent pressure calibrations are performed. The cavitation pressure is found to increase monotonically from -26MPa at 0°C to -17MPa at 80°C . While these values lie among the most negative pressures reported in water, they are still far away from the cavitation pressure expected theoretically and reached in the experiment by Angell and his group [Zheng , Science 254, 829 (1991)] (around -120MPa at 40°C ). Possible reasons for this discrepancy are considered.

  3. Automated Blood Pressure Measurement

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The Vital-2 unit pictured is a semi-automatic device that permits highly accurate blood pressure measurement, even by untrained personnel. Developed by Meditron Instrument Corporation, Milford, New Hampshire, it is based in part on NASA technology found in a similar system designed for automatic monitoring of astronauts' blood pressure. Vital-2 is an advancement over the familiar arm cuff, dial and bulb apparatus customarily used for blood pressure checks. In that method, the physician squeezes the bulb to inflate the arm cuff, which restricts the flow of blood through the arteries. As he eases the pressure on the arm, he listens, through a stethoscope, to the sounds of resumed blood flow as the arteries expand and contract. Taking dial readings related to sound changes, he gets the systolic (contracting) and diastolic (expanding) blood pressure measurements. The accuracy of the method depends on the physician's skill in interpreting the sounds. Hospitals sometimes employ a more accurate procedure, but it is "invasive," involving insertion of a catheter in the artery.

  4. Passive blast pressure sensor

    DOEpatents

    King, Michael J.; Sanchez, Roberto J.; Moss, William C.

    2013-03-19

    A passive blast pressure sensor for detecting blast overpressures of at least a predetermined minimum threshold pressure. The blast pressure sensor includes a piston-cylinder arrangement with one end of the piston having a detection surface exposed to a blast event monitored medium through one end of the cylinder and the other end of the piston having a striker surface positioned to impact a contact stress sensitive film that is positioned against a strike surface of a rigid body, such as a backing plate. The contact stress sensitive film is of a type which changes color in response to at least a predetermined minimum contact stress which is defined as a product of the predetermined minimum threshold pressure and an amplification factor of the piston. In this manner, a color change in the film arising from impact of the piston accelerated by a blast event provides visual indication that a blast overpressure encountered from the blast event was not less than the predetermined minimum threshold pressure.

  5. Pressure measurement on rotating machinery

    NASA Astrophysics Data System (ADS)

    Pemberton, Addison; Harris, Louis R.

    The objective of this paper is to describe the use of pressure scanners for measuring multiple unknown pressures in rotating machinery. Pressure scanners consist of stepper driven selector valves, which sequentially connect unknown pressures and apply these pressures to a single pressure transducer. This generates analog voltage signals which can be computerized and plotted while a pressure test is in progress. When an electrical selector switch on the same stepper driven shaft is added, thermocouple signals can be brought out of a rotating machine synchronously with pressure data.

  6. Sea level variation

    NASA Technical Reports Server (NTRS)

    Douglas, Bruce C.

    1992-01-01

    Published values for the long-term, global mean sea level rise determined from tide gauge records range from about one to three mm per year. The scatter of the estimates appears to arise largely from the use of data from gauges located at convergent tectonic plate boundaries where changes of land elevation give fictitious sea level trends, and the effects of large interdecadal and longer sea level variations on short (less than 50+ years) or sappy records. In addition, virtually all gauges undergo subsidence or uplift due to isostatic rebound from the last deglaciation at a rate comparable to or greater than the secular rise of sea level. Modeling rebound by the ICE-3G model of Tushingham and Peltier (1990) and avoiding tide gauge records in areas of converging tectonic plates produces a highly consistent set of long sea level records. A global set of 21 such stations in nine oceanic regions with an average record length of 76 years during the period 1880-1980 yields the global sea level rise value 1.8 mm/year +/- 0.1. Greenhouse warming scenarios commonly forecast an additional acceleration of global sea level in the next 5 or 6+ decades in the range 0.1-0.2 mm/yr2. Because of the large power at low frequencies in the sea level spectrum, very long tide gauge records (75 years minimum) have been examined for past apparent sea level acceleration. For the 80-year period 1905-1985, 23 essentially complete tide gauge records in 10 geographic groups are available for analysis. These yielded the apparent global acceleration -0.011 (+/- 0.012) mm/yr2. A larger, less uniform set of 37 records in the same 10 groups with 92 years average length covering the 141 years from 1850-1991 gave 0.001 (+/- 0.008) mm/yr2. Thus there is no evidence for an apparent acceleration in the past 100+ years that is significant either statistically, or in comparison to values associated with global warming. Unfortunately, the large interdecadal fluctuations of sea level severely affect

  7. Robust Understanding of Statistical Variation

    ERIC Educational Resources Information Center

    Peters, Susan A.

    2011-01-01

    This paper presents a framework that captures the complexity of reasoning about variation in ways that are indicative of robust understanding and describes reasoning as a blend of design, data-centric, and modeling perspectives. Robust understanding is indicated by integrated reasoning about variation within each perspective and across…

  8. Classifying Measures of Biological Variation

    PubMed Central

    Gregorius, Hans-Rolf; Gillet, Elizabeth M.

    2015-01-01

    Biological variation is commonly measured at two basic levels: variation within individual communities, and the distribution of variation over communities or within a metacommunity. We develop a classification for the measurement of biological variation on both levels: Within communities into the categories of dispersion and diversity, and within metacommunities into the categories of compositional differentiation and partitioning of variation. There are essentially two approaches to characterizing the distribution of trait variation over communities in that individuals with the same trait state or type tend to occur in the same community (describes differentiation tendencies), and individuals with different types tend to occur in different communities (describes apportionment tendencies). Both approaches can be viewed from the dual perspectives of trait variation distributed over communities (CT perspective) and community membership distributed over trait states (TC perspective). This classification covers most of the relevant descriptors (qualified measures) of biological variation, as is demonstrated with the help of major families of descriptors. Moreover, the classification is shown to open ways to develop new descriptors that meet current needs. Yet the classification also reveals the misclassification of some prominent and widely applied descriptors: Dispersion is often misclassified as diversity, particularly in cases where dispersion descriptor allow for the computation of effective numbers; the descriptor GST of population genetics is commonly misclassified as compositional differentiation and confused with partitioning-oriented differentiation, whereas it actually measures partitioning-oriented apportionment; descriptors of β-diversity are ambiguous about the differentiation effects they are supposed to represent and therefore require conceptual reconsideration. PMID:25807558

  9. Circumferential pressure probe

    NASA Technical Reports Server (NTRS)

    Holmes, Harlan K. (Inventor); Moore, Thomas C. (Inventor); Fantl, Andrew J. (Inventor)

    1989-01-01

    A probe for measuring circumferential pressure inside a body cavity is disclosed. In the preferred embodiment, a urodynamic pressure measurement probe for evaluating human urinary sphincter function is disclosed. Along the length of the probe are disposed a multiplicity of deformable wall sensors which typically comprise support tube sections with flexible side wall areas. These are arranged along the length of the probe in two areas, one just proximal to the tip for the sensing of fluid pressure inside the bladder, and five in the sensing section which is positioned within the urethra at the point at which the urinary sphincter constricts to control the flow of urine. The remainder of the length of the probe comprises multiple rigid support tube sections interspersed with flexible support tube sections in the form of bellows to provide flexibility.

  10. Magnetostrictive Pressure Regulating System

    NASA Technical Reports Server (NTRS)

    Richard, James A. (Inventor); Pickens, Herman L. (Inventor)

    2013-01-01

    A magnetostrictive pressure regulating system includes a magnetostrictive valve that incorporates a magnetostrictive actuator with at least one current-carrying coil disposed thereabout. A pressure force sensor, in fluid communication with the fluid exiting the valve, includes (i) a magnetostrictive material, (ii) a magnetic field generator in proximity to the magnetostrictive material for inducing a magnetic field in and surrounding the magnetostrictive material wherein lines of magnetic flux passing through the magnetostrictive material are defined, and (iii) a sensor positioned adjacent to the magnetostrictive material and in the magnetic field for measuring changes in at least one of flux angle and flux density when the magnetostrictive material experiences an applied force that is aligned with the lines of magnetic flux. The pressure of the fluid exiting the valve causes the applied force. A controller coupled to the sensor and to the current-carrying coil adjusts a current supplied to the current-carrying coil based on the changes so-measured.

  11. PRESSURE SENSING DEVICE

    DOEpatents

    Pope, K.E.

    1959-12-15

    This device is primarily useful as a switch which is selectively operable to actuate in response to either absolute or differential predetermined pressures. The device generally comprises a pressure-tight housing divided by a movable impermeable diaphragm into two chambers, a reference pressure chamber and a bulb chamber containing the switching means and otherwise filled with an incompressible non-conducting fluid. The switch means comprises a normally collapsed bulb having an electrically conductive outer surface and a vent tube leading to the housing exterior. The normally collapsed bulb is disposed such that upon its inflation, respensive to air inflow from the vent, two contacts fixed within the bulb chamber are adapted to be electrically shorted by the conducting outer surface of the bulb.

  12. HIGH PRESSURE GAS REGULATOR

    DOEpatents

    Ramage, R.W.

    1962-05-01

    A gas regulator operating on the piston and feedback principle is described. The device is particularly suitable for the delicate regulation of high pressure, i.e., 10,000 psi and above, gas sources, as well as being perfectly adaptable for use on gas supplies as low as 50 psi. The piston is adjustably connected to a needle valve and the movement of the piston regulates the flow of gas from the needle valve. The gas output is obtained from the needle valve. Output pressure is sampled by a piston feedback means which, in turn, regulates the movement of the main piston. When the output is other than the desired value, the feedback system initiates movement of the main piston to allow the output pressure to be corrected or to remain constant. (AEC)

  13. A Microwave Pressure Sounder

    NASA Technical Reports Server (NTRS)

    Flower, D. A.; Peckham, G. E.

    1978-01-01

    An instrument to measure atmospheric pressure at the earth's surface from an orbiting satellite would be a valuable addition to the expanding inventory of remote sensors. The subject of this report is such an instrument - the Microwave Pressure Sounder (MPS). It is shown that global-ocean coverage is attainable with sufficient accuracy, resolution and observational frequency for meteorological, oceanographic and climate research applications. Surface pressure can be deduced from a measurement of the absorption by an atmospheric column at a frequency in the wing of the oxygen band centered on 60 GHz. An active multifrequency instrument is needed to make this measurement with sufficient accuracy. The selection of optimum operating frequencies is based upon accepted models of surface reflection, oxygen, water vapor and cloud absorption. Numerical simulation using a range of real atmospheres defined by radiosonde observations were used to validate the frequency selection procedure. Analyses are presented of alternative system configurations that define the balance between accuracy and achievable resolution.

  14. Oxygen partial pressure sensor

    DOEpatents

    Dees, D.W.

    1994-09-06

    A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured. 1 fig.

  15. Oxygen partial pressure sensor

    DOEpatents

    Dees, Dennis W.

    1994-01-01

    A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured.

  16. Pressure suppression containment system

    DOEpatents

    Gluntz, Douglas M.; Townsend, Harold E.

    1994-03-15

    A pressure suppression containment system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and a gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel. The wetwell pool includes a plenum for receiving the non-condensable gas carried with steam from the drywell following a loss-of coolant-accident (LOCA). The wetwell plenum is vented to a plenum above the GDCS pool following the LOCA for suppressing pressure rise within the containment vessel. A method of operation includes channeling steam released into the drywell following the LOCA into the wetwell pool for cooling along with the non-condensable gas carried therewith. The GDCS pool is then drained by gravity, and the wetwell plenum is vented into the GDCS plenum for channeling the non-condensable gas thereto.

  17. Pressure suppression containment system

    DOEpatents

    Gluntz, D.M.; Townsend, H.E.

    1994-03-15

    A pressure suppression containment system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and a gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel. The wetwell pool includes a plenum for receiving the non-condensable gas carried with steam from the drywell following a loss-of-coolant-accident (LOCA). The wetwell plenum is vented to a plenum above the GDCS pool following the LOCA for suppressing pressure rise within the containment vessel. A method of operation includes channeling steam released into the drywell following the LOCA into the wetwell pool for cooling along with the non-condensable gas carried therewith. The GDCS pool is then drained by gravity, and the wetwell plenum is vented into the GDCS plenum for channeling the non-condensable gas thereto. 6 figures.

  18. The major influence of the atmosphere on intracranial pressure: an observational study

    NASA Astrophysics Data System (ADS)

    Herbowski, Leszek

    2016-06-01

    The impact of the atmosphere on human physiology has been studied widely within the last years. In practice, intracranial pressure is a pressure difference between intracranial compartments and the surrounding atmosphere. This means that gauge intracranial pressure uses atmospheric pressure as its zero point, and therefore, this method of pressure measurement excludes the effects of barometric pressure's fluctuation. The comparison of these two physical quantities can only take place through their absolute value relationship. The aim of this study is to investigate the direct effect of barometric pressure on the absolute intracranial pressure homeostasis. A prospective observational cross-sectional open study was conducted in Szczecin, Poland. In 28 neurosurgical patients with suspected normal-pressure hydrocephalus, intracranial intraventricular pressure was monitored in a sitting position. A total of 168 intracranial pressure and atmospheric pressure measurements were performed. Absolute atmospheric pressure was recorded directly. All values of intracranial gauge pressure were converted to absolute pressure (the sum of gauge intracranial pressure and local absolute atmospheric pressure). The average absolute mean intracranial pressure in the patients is 1006.6 hPa (95 % CI 1004.5 to 1008.8 hPa, SEM 1.1), and the mean absolute atmospheric pressure is 1007.9 hPa (95 % CI 1006.3 to 1009.6 hPa, SEM 0.8). The observed association between atmospheric and intracranial pressure is strongly significant (Spearman correlation r = 0.87, p < 0.05) and all the measurements are perfectly reliable (Bland-Altman coefficient is 4.8 %). It appears from this study that changes in absolute intracranial pressure are related to seasonal variation. Absolute intracranial pressure is shown to be impacted positively by atmospheric pressure.

  19. Wall pressure exerted by hydrogenation of sodium aluminum hydride.

    SciTech Connect

    Perras, Yon E.; Dedrick, Daniel E.; Zimmerman, Mark D.

    2009-06-01

    Wall pressure exerted by the bulk expansion of a sodium aluminum hydride bed was measured as a function of hydrogen content. A custom apparatus was designed and loaded with sodium alanates at densities of 1.0, 1.1, and 1.16 g/cc. Four complete cycles were performed to identify variations in measured pressure. Results indicated poor correlation between exerted pressure and hydrogen capacity of the sodium alanate beds. Mechanical pressure due to the hydrogenation of sodium alanates does not influence full-scale system designs as it falls within common design factors of safety. Gas pressure gradients within the porous solid were identified and may limit reaction rates, especially for high aspect ratio beds.

  20. Two-phase flows within systems with ambient pressure

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Braun, M. J.; Wheeler, R. L., III; Mullen, R. L.

    1985-01-01

    In systems where the design inlet and outlet pressures are maintained above the thermodynamic critical pressure, it is often assumed that two phase flows within the system cannot occur. Designers rely on this simple rule of thumb to circumvent problems associated with a highly compressible two phase flow occurring within the supercritical pressure system along with the uncertainties in rotordynamics, load capacity, heat transfer, fluid mechanics, and thermophysical property variations. The simple rule of thumb is adequate in many low power designs but is inadequate for high performance turbomachines and linear systems, where two phase regions can exist even though outlet pressure is greater than critical pressure. Rotordynamic-fluid-mechanic restoring forces depend on momentum differences, and those for a two phase zone can differ significantly from those for a single-phase zone. Using the Reynolds equation the angular velocity, eccentricity, geometry, and ambient conditions are varied to determine the point of two phase flow incipience.