Sample records for vapour pressure measurements

  1. Measurement and modeling of high-pressure (vapour + liquid) equilibria of (CO{sub 2} + alcohol) binary systems

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, Jorge E.; Bejarano, Arturo [Departamento de Ingenieria Quimica y Ambiental, Universidad Tecnica Federico Santa Maria, Avda. Espana 1680, Valparaiso (Chile); Fuente, Juan C. de la, E-mail: juan.delafuente@usm.c [Departamento de Ingenieria Quimica y Ambiental, Universidad Tecnica Federico Santa Maria, Avda. Espana 1680, Valparaiso (Chile); Centro Regional de Estudios en Alimentos Saludables, Blanco 1623, Valparaiso (Chile)


    An apparatus based on a static-analytic method assembled in this work was utilized to perform high pressure (vapour + liquid) equilibria measurements with uncertainties estimated at <5%. Complementary isothermal (vapour + liquid) equilibria results are reported for the (CO{sub 2} + 1-propanol), (CO{sub 2} + 2-methyl-1-propanol), (CO{sub 2} + 3-methyl-1-butanol), and (CO{sub 2} + 1-pentanol) binary systems at temperatures of (313, 323, and 333) K, and at pressure range of (2 to 12) MPa. For all the (CO{sub 2} + alcohol) systems, it was visually monitored to insure that there was no liquid immiscibility at the temperatures and pressures studied. The experimental results were correlated with the Peng-Robinson equation of state using the quadratic mixing rules of van der Waals with two adjustable parameters. The calculated (vapour + liquid) equilibria compositions were found to be in good agreement with the experimental values with deviations for the mol fractions <0.12 and <0.05 for the liquid and vapour phase, respectively.

  2. Micrometeorological measurements and vapour pressure deficit relations under in-field rainwater harvesting (United States)

    Tesfuhuney, Weldemichael A.; Walker, Sue; Van Rensburg, Leon D.; Steyn, A. Stephan


    In a cropped field, microclimate and thermal stability conditions depend on the canopy structures and the prevailing weather. The main aim of the study therefore was to characterize the vertical profiles of weather variables within and above a maize (Zea mays L.) canopy and to describe the water vapour pressure deficit (VPD) under different atmospheric and soil surface conditions for both wide and narrow runoff strips with the in-field rainwater harvesting (IRWH) system. Micrometeorological measurements of wind, temperature and relative humidity were performed at eight levels, within canopy (1.8 and 2.1 m), and just above the canopy (2.4, 2.7, 3.0, and 3.3 m) up to reference levels (3.9 and 4.5 m) when the maize reached a maximum height of 2.2 m. Under incomplete canopy cover of the IRWH system, two important factors complicated evapotranspiration estimation, namely the local advection and high temperatures of the bare soil between adjacent plant rows. Diurnal variations of water vapour related to turbulence at each locality and its position in the thermal internal boundary layers. Generally, advection was more pronounced in wide runoff strips than narrow strips. On wide runoff strips the wind was more effective in replacing the air between the rows and maintained a higher driving force for evaporation. The maximum VPD over the narrow strips was observed at reference level during a dry day, at about 2.2 kPa in the afternoon, while wet day VPD reached a maximum of 1.8 kPa. The VPD of the wide runoff strips correlated negatively with wind speed, but showed a fairly positive correlation with some scattered values on wet days after rain. Therefore, profile characteristics within and above plant canopies played a key role in determining the VPD and consequently, could help to explain transpiration rates of crops. Hence, VPD relations enhanced the understanding of the heat energy exchange processes under the heterogeneous nature of maize canopy of the IRWH tillage system.

  3. Raspberry Ketone Analogs: Vapour Pressure Measurements and Attractiveness to Queensland Fruit Fly, Bactrocera tryoni (Froggatt (Diptera: Tephritidae.

    Directory of Open Access Journals (Sweden)

    Soo J Park

    Full Text Available The Queensland fruit fly, Bactrocera tryoni (Froggatt (Q-fly, is a major horticultural pest in Eastern Australia. Effective monitoring, male annihilation technique (MAT and mass trapping (MT are all important for control and require strong lures to attract flies to traps or toxicants. Lure strength is thought to be related in part to volatility, but little vapour pressure data are available for most Q-fly lures. Raspberry ketone (4-(4-hydroxyphenyl-2-butanone and analogs that had esters (acetyl, difluoroacetyl, trifluoroacetyl, formyl, propionyl and ethers (methyl ether, trimethylsilyl ether in replacement of the phenolic group, and in one case also had modification of the 2-butanone side chain, were measured for their vapour pressures by differential scanning calorimetry (DSC, and their attractiveness to Q-fly was assessed in small cage environmentally controlled laboratory bioassays. Maximum response of one category of compounds, containing both 2-butanone side chain and ester group was found to be higher than that of the other group of compounds, of which either of 2-butanone or ester functionality was modified. However, linear relationship between vapour pressure and maximum response was not significant. The results of this study indicate that, while volatility may be a factor in lure effectiveness, molecular structure is the dominating factor for the series of molecules investigated.

  4. Raspberry Ketone Analogs: Vapour Pressure Measurements and Attractiveness to Queensland Fruit Fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae). (United States)

    Park, Soo J; Morelli, Renata; Hanssen, Benjamin L; Jamie, Joanne F; Jamie, Ian M; Siderhurst, Matthew S; Taylor, Phillip W


    The Queensland fruit fly, Bactrocera tryoni (Froggatt) (Q-fly), is a major horticultural pest in Eastern Australia. Effective monitoring, male annihilation technique (MAT) and mass trapping (MT) are all important for control and require strong lures to attract flies to traps or toxicants. Lure strength is thought to be related in part to volatility, but little vapour pressure data are available for most Q-fly lures. Raspberry ketone (4-(4-hydroxyphenyl)-2-butanone) and analogs that had esters (acetyl, difluoroacetyl, trifluoroacetyl, formyl, propionyl) and ethers (methyl ether, trimethylsilyl ether) in replacement of the phenolic group, and in one case also had modification of the 2-butanone side chain, were measured for their vapour pressures by differential scanning calorimetry (DSC), and their attractiveness to Q-fly was assessed in small cage environmentally controlled laboratory bioassays. Maximum response of one category of compounds, containing both 2-butanone side chain and ester group was found to be higher than that of the other group of compounds, of which either of 2-butanone or ester functionality was modified. However, linear relationship between vapour pressure and maximum response was not significant. The results of this study indicate that, while volatility may be a factor in lure effectiveness, molecular structure is the dominating factor for the series of molecules investigated.

  5. Raspberry Ketone Analogs: Vapour Pressure Measurements and Attractiveness to Queensland Fruit Fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae)


    Park, Soo J.; Morelli, Renata; Hanssen, Benjamin L.; Jamie, Joanne F.; Jamie, Ian M.; Siderhurst, Matthew S.; Taylor, Phillip W.


    The Queensland fruit fly, Bactrocera tryoni (Froggatt) (Q-fly), is a major horticultural pest in Eastern Australia. Effective monitoring, male annihilation technique (MAT) and mass trapping (MT) are all important for control and require strong lures to attract flies to traps or toxicants. Lure strength is thought to be related in part to volatility, but little vapour pressure data are available for most Q-fly lures. Raspberry ketone (4-(4-hydroxyphenyl)-2-butanone) and analogs that had esters...

  6. Intercomparison on measurement of water vapour permeability

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard

    Three different materials are tested - hard woodfibre board - damp proof course - underlay for roofing The water vapour permeability has been measured according to EN ISO 12572 (2001).......Three different materials are tested - hard woodfibre board - damp proof course - underlay for roofing The water vapour permeability has been measured according to EN ISO 12572 (2001)....

  7. Estimation of vapour pressure and partial pressure of subliming ...

    Indian Academy of Sciences (India)


    temperature curves are calculated at 80, 160 and 1000 mbar for salicylic acid and vanadyl bis-2,4- pentanedionate, a precursor used for chemical vapour deposition of vanadium oxides. Using a modification of the Langmuir equation, the partial pressure of these materials at different total pressures is also determined.

  8. Water vapour loss measurements on human skin.

    NARCIS (Netherlands)

    Valk, Petrus Gerardus Maria van der


    In this thesis, the results of a series of investigations into the barrier function of human skin are presented. In these investigations, the barrier function was assessed by water vapour loss measurements of the skin using a method based on gradient estimation.... Zie: Summary and conclusions

  9. Water vapour measurements during POLINAT 1

    Energy Technology Data Exchange (ETDEWEB)

    Ovarlez, J.; Ovarlez, H. [Centre National de la Recherche Scientifique, 91 - Palaiseau (France). Lab. de Meteorologie Dynamique


    The POLINAT (POLlution from aircraft emissions In the North ATlantic flight corridor)1 experiment has been performed within the framework of the Environment Programme of the Commission of the European Community. It was devoted to the study of the pollution from aircraft in the North Atlantic flight corridor, in order to investigate the impact of pollutants emitted by aircraft on the concentrations of ozone and other trace gases in the upper troposphere and lower stratosphere. For that experiment the water vapour content was measured with a frost-point hygrometer on board of the DLR Falcon research aircraft. This instrument is described, and some selected results are given. (author) 19 refs.

  10. Droplet spectrum at different vapour pressure deficits1

    Directory of Open Access Journals (Sweden)

    Christiam Felipe Silva Maciel

    Full Text Available ABSTRACT An efficient pesticides spraying depends a lot in psychrometric conditions, mainly if it is using fine droplets, once climatic conditions may cause droplets evaporation and consequent financial loss to the farmer. Thus, the aim of this work was to determine the droplet spectrum depending on the vapour pressure deficits. The work was carried out inside of a climate chamber to obtain the vapour pressure deficits (VPDair. The laser particle analyzer, model Spraytech, was used to determine the droplet spectrum, and the experiment was conducted in factorial scheme 5 x 20, consisted of five working pressures (100; 200; 300; 400 and 500 kPa and twenty VPDair (2.3; 3.2; 4.2; 5.6; 7.0; 7.4; 9.5; 11.7; 12.7; 15.8; 16.4; 16.9; 21.2; 22.1; 22.2; 28.1; 29.7; 36.9 39.4 e 51.6 hPa, in completely randomized design with five replications. There is influence of VPDair on droplet spectrum behavior. Increasing the VPDair reduces the percentage of sprayed volume comprised by droplets with diameter between 100 and 200 µm, between 200 and 300 µm, between 300 and 400 µm, between 400 and 500 µm and between 500 and 600 µm. Increasing VPDair increases the VMD, Dv90, SPAN and the percentage of sprayed volume comprised by droplets larger than 600 µm.

  11. Combustion dynamics of low vapour pressure nanofuel droplets (United States)

    Pandey, Khushboo; Chattopadhyay, Kamanio; Basu, Saptarshi


    Multiscale combustion dynamics, shape oscillations, secondary atomization, and precipitate formation have been elucidated for low vapour pressure nanofuel [n-dodecane seeded with alumina nanoparticles (NPs)] droplets. Dilute nanoparticle loading rates (0.1%-1%) have been considered. Contrary to our previous studies of ethanol-water blend (high vapour pressure fuel), pure dodecane droplets do not exhibit internal boiling after ignition. However, variation in surface tension due to temperature causes shape deformations for pure dodecane droplets. In the case of nanofuels, intense heat release from the enveloping flame leads to the formation of micron-size aggregates (of alumina NPS) which serve as nucleation sites promoting heterogeneous boiling. Three boiling regimes (A, B, and C) have been identified with varying bubble dynamics. We have deciphered key mechanisms responsible for the growth, transport, and rupture of the bubbles. Bubble rupture causes ejections of liquid droplets termed as secondary atomization. Ejection of small bubbles (mode 1) resembles the classical vapour bubble collapse mechanism near a flat free surface. However, large bubbles induce severe shape deformations as well as bulk oscillations. Rupture of large bubbles results in high speed liquid jet formation which undergoes Rayleigh-Plateau tip break-up. Both modes contribute towards direct fuel transfer from the droplet surface to flame envelope bypassing diffusion limitations. Combustion lifetime of nanofuel droplets consequently has two stages: stage I (where bubble dynamics are dominant) and stage II (formation of gelatinous mass due to continuous fuel depletion; NP agglomeration). In the present work, variation of flame dynamics and spatio-temporal heat release (HR) have been analysed using high speed OH* chemiluminescence imaging. Fluctuations in droplet shape and flame heat release are found to be well correlated. Droplet flame is bifurcated in two zones (I and II). Flame response is


    Directory of Open Access Journals (Sweden)

    Peter Pikna


    Full Text Available Thin film polycrystalline silicon (poly-Si solar cells were annealed in water vapour at pressures below atmospheric pressure. PN junction of the sample was contacted by measuring probes directly in the pressure chamber filled with steam during passivation. Suns-VOC method and a Lock-in detector were used to monitor an effect of water vapour to VOC of the solar cell during whole passivation process (in-situ. Tested temperature of the sample (55°C – 110°C was constant during the procedure. Open-circuit voltage of a solar cell at these temperatures is lower than at room temperature. Nevertheless, voltage response of the solar cell to the light flash used during Suns-VOC measurements was good observable. Temperature dependences for multicrystalline wafer-based and polycrystalline thin film solar cells were measured and compared. While no significant improvement of thin film poly-Si solar cell parameters by annealing in water vapour at under-atmospheric pressures was observed up to now, in-situ observation proved required sensitivity to changing VOC at elevated temperatures during the process.

  13. Atmospheric pressure vapour phase decomposition: a proof of principle. (United States)

    Cinosi, Amedeo; Andriollo, Nunzio; Tibaldi, Francesca; Monticelli, Damiano


    In the present work we demonstrated that the digestion of difficult matrices (high boiling petrochemical fractions and distillation bottoms) can be achieved by oxidation with nitric acid vapours at atmospheric pressure employing simple laboratory glassware. The application of this procedure as a digestion method prior to Total Reflection X-Ray Fluorescence (TXRF) is presented, although the employment of other detection techniques may be foreseen. The method ensured a fast, less than half an hour, treatment time and detection limits in the range 20-100 μg/kg for As, Bi, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, Zn, whereas higher values were obtained for Ba, Ca, K, P, Rh, Ti and V (0.3-3 mg/kg). The potentialities and limitations of this procedure were discussed: the application to a broad range of matrices may be foreseen. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Measurements of Isotopic Composition of Vapour on the Antarctic Plateau (United States)

    Casado, M.; Landais, A.; Masson-Delmotte, V.; Genthon, C.; Prie, F.; Kerstel, E.; Kassi, S.; Arnaud, L.; Steen-Larsen, H. C.; Vignon, E.


    The oldest ice core records are obtained on the East Antarctic plateau. The composition in stable isotopes of water (δ18O, δD, δ17O) permits to reconstruct the past climatic conditions over the ice sheet and also at the evaporation source. Paleothermometer accuracy relies on good knowledge of processes affecting the isotopic composition of surface snow in Polar Regions. Both simple models such as Rayleigh distillation and global atmospheric models with isotopes provide good prediction of precipitation isotopic composition in East Antarctica but post deposition processes can alter isotopic composition on site, in particular exchanges with local vapour. To quantitatively interpret the isotopic composition of water archived in ice cores, it is thus essential to study the continuum water vapour - precipitation - surface snow - buried snow. While precipitation and snow sampling are routinely performed in Antarctica, climatic conditions in Concordia, very cold (-55°C in average) and very dry (less than 1000ppmv), impose difficult conditions to measure the water vapour isotopic composition. New developments in infrared spectroscopy enable now the measurement of isotopic composition in water vapour traces (down to 20ppmv). Here we present the results of a campaign of measurement of isotopic composition in Concordia in 2014/2015. Two infrared spectrometers have been deployed or the first time on top of the East Antarctic Plateau allowing a continuous vapour measurement for a month. Comparison of the results from infrared spectroscopy with cryogenic trapping validates the relevance of the method to measure isotopic composition in dry conditions. Identification of different behaviour of isotopic composition in the water vapour associated to turbulent or stratified regime indicates a strong impact of meteorological processes in local vapour/snow interaction.

  15. Methods for estimating the vapour pressure of organic chemicals; Application to five pesticides

    NARCIS (Netherlands)

    Leistra, M.


    When studying and modelling the volatilisation of pesticides from crops, their vapour pressure is an essential property. In the critical evaluation of vapour pressures stated by various sources, problems were encountered. Therefore, an inventory was made of readily-usable methods for estimating

  16. Axial mercury vapour pressure distributions in DC operated low pressure mercury argon discharges (United States)

    Gielen, John; de Groot, Simon; van Dijk, Jan; van der Mullen, Joost


    In a steady state DC operated (cylindrical) low pressure mercury argon discharge, an electric field exists in axial direction which results in a non-uniform axial mercury vapour pressure distribution; this phenomenon is termed cataphoresis. In a discharge tube covered with a fluorescent powder this gives in a non-uniform axial light distribution. Towards lighting applications this is a potential disadvantage, which is not present in AC operated fluorescent lamps. The dependence of the axial mercury vapour pressure distribution under DC operation on discharge tube and discharge parameters has been investigated. A model has been developed to predict the axial mercury vapour pressure distribution, in which the balance equations for particle and momentum conservation are solved in combination with a plasma physical model, and experiments have been performed to validate the model. In the present contribution the model and experimental results will be discussed and it will be demonstrated that the applied theoretical approach provides a better description of the axial mercury vapour pressure distribution compared to previous models known from literature.

  17. Low pressure water vapour plasma treatment of surfaces for biomolecules decontamination

    DEFF Research Database (Denmark)

    Fumagalli, F; Kylian, O; Amato, Letizia


    Decontamination treatments of surfaces are performed on bacterial spores, albumin and brain homogenate used as models of biological contaminations in a low-pressure, inductively coupled plasma reactor operated with water-vapour-based gas mixtures. It is shown that removal of contamination can...... vapour plasma process are discussed for practical applications in medical devices decontamination....

  18. Erratum to: Measurement of copper vapour laser-induced ...

    Indian Academy of Sciences (India)

    Erratum to: Measurement of copper vapour laser-induced deformation of dielectric-coated mirror surface by. Michelson interferometer. A WAHID. ∗. , S KUNDU, J S B SINGH, A K SINGH, A KHATTAR,. S K MAURYA, J S DHUMAL and K DASGUPTA. Laser & Plasma Technology Division, Beam Technology Development ...

  19. Signal transduction pathway(s) in guard cells after prolonged exposure to low vapour pressure deficit

    NARCIS (Netherlands)

    Ali Niaei Fard, S.


    Keywords: Abscisic acid, Arabidopsis thaliana, calcium, CYP707As, desiccation, environmental factors, guard cells’ signalling pathway, hydrogen peroxide, natural variation, nitric oxide, photosystem II efficiency, RD29A, relative water content, secondary messengers, stomata, vapour pressure

  20. Low pressure chemical vapour deposition at quasi-high flow

    NARCIS (Netherlands)

    Holleman, J.; Middelhoek, Jan


    A new chemical vapour deposition (CVD) technique is presented. It is especially advantageous for the deposition of compound materials. The technique improves the uniformity and reproducibility of the deposition. The economical use of gaseous reactants is improved by a factor varying between 5 and

  1. Excess properties and vapour pressure of left brace3-diethylaminopropylamine + cyclohexaneright brace

    Energy Technology Data Exchange (ETDEWEB)

    Khimeche, Kamel, E-mail: kamel.khimeche@yahoo.f [Ecole Militaire Polytechnique EMP, BP 17 Bordj-El-Bahri, Alger (Algeria); Dahmani, Abdallah [Laboratoire de thermodynamique et modelisation moleculaire, Faculte de chimie, USTHB, BP 32 El-Alia, 16111 Bab-Ezzouar, Alger (Algeria); Mokbel, Ilham [Laboratoire de chimie analytique I, Universite Claude Bernard (Lyon I), 43, bd du 11 Novembre 1918 69622 Villeurbanne (France)


    The vapour pressures of liquid left brace3-diethylaminopropylamine (3-DEPA) + cyclohexaneright brace were measured by a static method between T = (273.15 and 363.15) K at 10 K intervals. The excess molar volumes V{sup E} at 298.15 K and excess molar enthalpies H{sup E} at 303.15 K were also measured. The molar excess Gibbs free energies G{sup E} were obtained with Barker's method and fitted to the Redlich-Kister equation. The Wilson equation was also used. Deviations between experimental and predicted G{sup E} and H{sup E}, by using DISQUAC model, were evaluated

  2. Translation Effects in Fluorine Doped Tin Oxide Thin Film Properties by Atmospheric Pressure Chemical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    Mohammad Afzaal


    Full Text Available In this work, the impact of translation rates in fluorine doped tin oxide (FTO thin films using atmospheric pressure chemical vapour deposition (APCVD were studied. We demonstrated that by adjusting the translation speeds of the susceptor, the growth rates of the FTO films varied and hence many of the film properties were modified. X-ray powder diffraction showed an increased preferred orientation along the (200 plane at higher translation rates, although with no actual change in the particle sizes. A reduction in dopant level resulted in decreased particle sizes and a much greater degree of (200 preferred orientation. For low dopant concentration levels, atomic force microscope (AFM studies showed a reduction in roughness (and lower optical haze with increased translation rate and decreased growth rates. Electrical measurements concluded that the resistivity, carrier concentration, and mobility of films were dependent on the level of fluorine dopant, the translation rate and hence the growth rates of the deposited films.

  3. The beauty of frost: nano-sulfur assembly via low pressure vapour deposition. (United States)

    Wang, Yu; Chen, Lu; Scudiero, Louis; Zhong, Wei-Hong


    A low pressure vapour deposition (LPVD) technique is proposed as an environmentally friendly, cost-effective and versatile strategy for fabrication of sulfur nanomaterials. By controlling the characteristics of the deposit substrate for the LPVD, various sulfur-based nanomaterials have been obtained through a substrate-induced self-assembly process.

  4. An Investigation of Tertiary Students' Understanding of Evaporation, Condensation and Vapour Pressure. Research Report (United States)

    Gopal, Hemant; Kleinsmidt, Jacques; Case, Jennifer; Musonge, Paul


    Based on a purposive sample of 15 second-year chemical engineering students, this study investigates students' conceptions of evaporation, condensation and vapour pressure. During individual interviews the students were questioned on three tasks that had been designed around these topics. Qualitative analysis of student responses showed a range of…

  5. An Investigation of Tertiary Students' Understanding of Evaporation, Condensation and Vapour Pressure (United States)

    Gopal, Hemant; Kleinsmidt, Jacques; Case, Jennifer; Musonge, Paul


    Based on a purposive sample of 15 second-year chemical engineering students, this study investigates students' conceptions of evaporation, condensation and vapour pressure. During individual interviews the students were questioned on three tasks that had been designed around these topics. Qualitative analysis of student responses showed a range of…

  6. Hydrogen and carbon vapour pressure isotope effects in liquid fluoroform studied by density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Oi, Takao; Mitome, Ryota; Yanase, Satoshi [Sophia Univ., Tokyo (Japan). Faculty of Science and Technology


    H/D and {sup 12}C/{sup 13}C vapour pressure isotope effects (VPIEs) in liquid fluoroform (CHF{sub 3}) were studied at the MPW1PW91/6-31 ++ G(d) level of theory. The CHF{sub 3} monomer and CHF{sub 3} molecules surrounded by other CHF{sub 3} molecules in every direction in CHF{sub 3} clusters were used as model molecules of vapour and liquid CHF{sub 3}. Although experimental results in which the vapour pressure of liquid {sup 12}CHF{sub 3} is higher than that of liquid {sup 12}CDF{sub 3} and the vapour pressure of liquid {sup 13}CHF{sub 3} is higher than that of liquid {sup 12}CHF{sub 3} between 125 and 212 K were qualitatively reproduced, the present calculations overestimated the H/D VPIE and underestimated the {sup 12}C/{sup 13}C VPIE. Temperature-dependent intermolecular interactions between hydrogen and fluorine atoms of neighbouring molecules were required to explain the temperature dependences of both H/D and {sup 12}C/{sup 13}C VPIEs.

  7. Solid state and sub-cooled liquid vapour pressures of substituted dicarboxylic acids using Knudsen Effusion Mass Spectrometry (KEMS and Differential Scanning Calorimetry

    Directory of Open Access Journals (Sweden)

    A. M. Booth


    Full Text Available Solid state vapour pressures of a selection of atmospherically important substituted dicarboxylic acids have been measured using Knudsen Effusion Mass Spectrometry (KEMS over a range of 20 K (298–318 K. Enthalpies of fusion and melting points obtained using Differential Scanning Calorimetry (DSC were used to obtain sub-cooled liquid vapour pressures. They have been compared to estimation methods used on the E-AIM website. These methods are shown to poorly represent – OH groups in combination with COOH groups. Partitioning calculations have been performed to illustrate the impact of the different estimation methods on organic aerosol mass compared to the use of experimental data.

  8. Temperature dependence vapour pressure measurements of Mg(tmhd){sub 2}(tmeda) [tmhd = 2,2,6,6-tetramethyl-3,5-heptanedione, tmeda = N,N,N',N'-tetramethylethylenediamine

    Energy Technology Data Exchange (ETDEWEB)

    Maria, Mathew; Selvakumar, J. [Department of Chemistry, Loyola Institute of Frontier Energy, Loyola College, Chennai 600034 (India); Raghunathan, V.S. [Non Ferrous Material Technology Development Center, Hyderabad 500050 (India); Mathews, Tom [Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Nagaraja, K.S. [Department of Chemistry, Loyola Institute of Frontier Energy, Loyola College, Chennai 600034 (India)], E-mail:


    The reaction between the magnesium {beta}-diketonate complex Mg(tmhd){sub 2}(H{sub 2}O){sub 2} and 1 equiv. of N,N,N',N'-tetramethylethylenediamine (tmeda = Me{sub 2}NCH{sub 2}CH{sub 2}NMe{sub 2}) in hexane at room temperature yielded Mg(tmhd){sub 2}(tmeda). The standard enthalpy of sublimation (83.2 {+-} 2.3 kJ mol{sup -1}) and entropy of sublimation (263 {+-} 6.3 J mol{sup -1} K{sup -1}) of Mg(tmhd){sub 2}(tmeda) were obtained from the temperature dependence vapour pressure, determined by adopting a horizontal dual arm single furnace thermogravimetric analyser as a transpiration apparatus. From the observed melting point depression DTA, the standard enthalpy of fusion (58.3 {+-} 5.2 kJ mol{sup -1}) was evaluated, using the ideal eutectic behaviour of Mg(tmhd){sub 2}(tmeda) as a solvent with bis(2,4-pentanedionato)magnesium(II), Mg(acac){sub 2} as a non-volatile solute.

  9. Stomatal acclimation to vapour pressure deficit doubles transpiration of small tree seedlings with warming

    DEFF Research Database (Denmark)

    Marchin, Renée M.; Broadhead, Alice A.; Bostic, Laura E.


    Future climate change is expected to increase temperature (T) and atmospheric vapour pressure deficit (VPD) in many regions, but the effect of persistent warming on plant stomatal behaviour is highly uncertain. We investigated the effect of experimental warming of 1.9-5.1 °C and increased VPD of ...... with increasing VPD and may necessitate revision of current models based on this assumption....

  10. Explicit modelling of SOA formation from α-pinene photooxidation: sensitivity to vapour pressure estimation

    Directory of Open Access Journals (Sweden)

    R. Valorso


    Full Text Available The sensitivity of the formation of secondary organic aerosol (SOA to the estimated vapour pressures of the condensable oxidation products is explored. A highly detailed reaction scheme was generated for α-pinene photooxidation using the Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A. Vapour pressures (Pvap were estimated with three commonly used structure activity relationships. The values of Pvap were compared for the set of secondary species generated by GECKO-A to describe α-pinene oxidation. Discrepancies in the predicted vapour pressures were found to increase with the number of functional groups borne by the species. For semi-volatile organic compounds (i.e. organic species of interest for SOA formation, differences in the predicted Pvap range between a factor of 5 to 200 on average. The simulated SOA concentrations were compared to SOA observations in the Caltech chamber during three experiments performed under a range of NOx conditions. While the model captures the qualitative features of SOA formation for the chamber experiments, SOA concentrations are systematically overestimated. For the conditions simulated, the modelled SOA speciation appears to be rather insensitive to the Pvap estimation method.

  11. The critical assessment of vapour pressure estimation methods for use in modelling the formation of atmospheric organic aerosol

    Directory of Open Access Journals (Sweden)

    M. H. Barley


    Full Text Available A selection of models for estimating vapour pressures have been tested against experimental data for a set of compounds selected for their particular relevance to the formation of atmospheric aerosol by gas-liquid partitioning. The experimental vapour pressure data (all <100 Pa of 45 multifunctional compounds provide a stringent test of the estimation techniques, with a recent complex group contribution method providing the best overall results. The effect of errors in vapour pressures upon the formation of organic aerosol by gas-liquid partitioning in an atmospherically relevant example is also investigated. The mass of organic aerosol formed under typical atmospheric conditions was found to be very sensitive to the variation in vapour pressure values typically present when comparing estimation methods.

  12. Blood pressure measurement (United States)

    ... reading; Measuring blood pressure; Hypertension - blood pressure measurement; High blood pressure - blood pressure measurement ... High blood pressure has no symptoms so you may not know if you have this problem. High blood pressure ...

  13. Pulsed metastable atom source for low vapour-pressure metals

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Urena, A.; Verdasco Costales, E. (Universidad Complutense de Madrid (Spain). Facultad de Quimica); Saez Rabanos, V. (Universidad Politecnica de Madrid (Spain). Escuela Tecnica Superior de Ingenieros Industriales)


    The basic design and most relevant experimental conditions of a pulsed metastable atomic-beam oven are described. The stainless steel oven is suitable for vaporising metals and salts up to around 1400 K producing intense beams of metastable alkaline-earth atoms when pulsed or continuous wave low voltage discharges are used. Several applications using atomic calcium in its {sup 3}P and {sup 1}D electronic state are reported. The beam characterisation and discharge efficiency have been measured by time-of-flight or laser-induced fluorescence techniques. In addition, a method of changing the metastable n{sup 3}P/n{sup 1}D ratio, by raising the oven temperature, is described which looks very promising for the study of electronic selectivity in reactive collision processes. Finally several spectroscopic applications for atomic and molecular beam determinations are reported. (author).

  14. Controlled nanostructured silver coated surfaces by atmospheric pressure chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Sheel, D.W.; Brook, L.A.; Yates, H.M. [Institute for Materials Research, Salford University, Manchester, M5 4 WT (United Kingdom)


    Thin film silver has been widely reported for its interesting properties. In this paper we describe a route to produce controlled nanostructured silver layers. A combination of Flame Assisted Chemical Vapour Deposition at atmospheric pressure, with low cost and a low toxicity silver precursor, was used to generate coatings of structured silver surfaces on glass. This approach gives a high degree of control of surface structure, density and topography. These layers have potential applications in areas such as catalysis, photo-activity and for biocidal surfaces. Our results indicate very high biocidal activity where the nano-structure is proposed as playing a significant role. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  15. Vapour pressure dependence and thermodynamics of cylindrical metal-organic framework mesoparticles: an ESEM study. (United States)

    Sievers, Torsten K; Genre, Caroline; Bonnefond, Florent; Demars, Thomas; Ravaux, Johann; Meyer, Daniel; Podor, Renaud


    Self-assembly of neodymium nitrate and 2,5-dihydroxyl-1,4-benzoquinone (DHBQ) leads to the formation of a metal organic framework (MOF) of formula [Nd2(DHBQ)3(H2O)6]·18H2O. X-ray diffraction studies show that its crystalline structure is that of a two-dimensional coordination polymer packed in parallel sheets, with organised clusters of water molecules lying between the sheets and bridging them via a dense H-bond network. However, instead of forming faceted crystals, this MOF assembles into unusually shaped cylindrical particles of micrometre size. Scanning electron microscopy revealed that the particles are indeed mesoparticles from aggregated MOF crystalline nano-grains. The mesoparticles are stimuli-responsive and shrink in size upon exposure to reduced water vapour pressure. The shrinkage is isotropic and depends on temperature, which allows measuring the coexistence curve of water inside the particles and in the gas phase. Owing to an elaborated environmental scanning-electron microscopy (ESEM) study, it was possible to determine the association energy of water in the mesoparticles. We found a value of 16 ± 6.5 kJ mol(-1). Since the only water present in the particles is the lattice water in the nano-grains, this association energy is the lattice energy of water in the nano-sized MOF crystals. This value allowed us to draw a model for the building process of these originally shaped cylindrical mesoparticles. This is the first example of determination of a thermodynamic value by ESEM.

  16. Stomatal sensitivity to vapour pressure deficit relates to climate of origin in Eucalyptus species. (United States)

    Bourne, Aimee E; Haigh, Anthony M; Ellsworth, David S


    Selecting plantation species to balance water use and production requires accurate models for predicting how species will tolerate and respond to environmental conditions. Although interspecific variation in water use occurs, species-specific parameters are rarely incorporated into physiologically based models because often the appropriate species parameters are lacking. To determine the physiological control over water use in Eucalyptus, five stands of Eucalyptus species growing in a common garden were measured for sap flux rates and their stomatal response to vapour pressure deficit (D) was assessed. Maximal canopy conductance and whole-canopy stomatal sensitivity to D and reduced water availability were lower in species originating from more arid climates of origin than those from humid climates. Species from humid climates showed a larger decline in maximal sap flux density (JSmax) with reduced water availability, and a lower D at which stomatal closure occurred than species from more arid climates, implying larger sensitivity to water availability and D in these species. We observed significant (P < 0.05) correlations of species climate of origin with mean vessel diameter (R(2) = 0.90), stomatal sensitivity to D (R(2) = 0.83) and the size of the decline in JSmax to restricted water availability (R(2) = 0.94). Thus aridity of climate of origin appears to have a selective role in constraining water-use response among the five Eucalyptus plantation species. These relationships emphasize that within this congeneric group of species, climate aridity constrains water use. These relationships have implications for species choices for tree plantation success against drought-induced losses and the ability to manage Eucalyptus plantations against projected changes in water availability and evaporation in the future. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email:

  17. First retrieval of global water vapour column amounts from SCIAMACHY measurements

    Directory of Open Access Journals (Sweden)

    S. Noël


    Full Text Available Global water vapour column amounts have been derived for the first time from measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY on the European environmental satellite ENVISAT. For this purpose, two different existing retrieval algorithms have been adapted, namely the Air Mass Corrected Differential Absorption Spectroscopy (AMC-DOAS which was originally designed for GOME and the Weighting Function Modified Differential Absorption Spectroscopy (WFM-DOAS which was mainly designed for the retrieval of CH4, CO2 and CO from SCIAMACHY near-infrared spectra. Here, both methods have been applied to SCIAMACHY's nadir measurements in the near-visible spectral region around 700 nm. Taking into account a systematic offset of 10%, the results of these two methods agree within a scatter of about ±0.5 g/cm2 with corresponding SSM/I and ECMWF water vapour data. This deviation includes contributions from the temporal and spatial variability of water vapour. In fact, the mean deviation between the SCIAMACHY and the correlative data sets is much smaller: the SCIAMACHY total water vapour columns are typically about 0.15 g/cm2 lower than the SSM/I values and less than 0.1 g/cm2 lower than corresponding ECMWF data. The SCIAMACHY water vapour results agree well with correlative data not only over ocean but also over land, thus showing the capability of SCIAMACHY to derive water vapour concentrations on the global scale.

  18. Heat transfer resistances in the measurements of cold helium vapour temperature in a subatmospheric process line (United States)

    Adamczyk, A.; Pietrowicz, S.; Fydrych, J.


    The superfluid helium technology, which is essentially used in particle accelerators, requires complex cryogenic systems that include long lines transferring cold helium vapours at a subathmospheric pressure below 50 mbar. Usually in large systems the subatmospheric pressure is generated by a set of warm and cold compressors. In consequence, the heat loads to the line and especially the helium temperature in the inlet to the cold compressors are crucial parameters. In order to measure the helium temperature the temperature sensors are usually fixed to the external surface of the process lines. However, this technique can lead to unwanted measurement errors and affect the temperature measurement dynamics mainly due to low thermal conductivity of the pipe wall material, large pipe diameters and low helium density. Assembling a temperature sensor in a well (cold finger) reaching the centerline of the flowing helium is a technique that can improve the measurement quality and dynamics (response time). The paper presents the numerical simulations of heat transfers occurring in the both measurement techniques and discusses the impacts of the heat transfer resistances on the temperature measurement dynamics.

  19. EVAPORATION: a new vapour pressure estimation methodfor organic molecules including non-additivity and intramolecular interactions

    Directory of Open Access Journals (Sweden)

    S. Compernolle


    Full Text Available We present EVAPORATION (Estimation of VApour Pressure of ORganics, Accounting for Temperature, Intramolecular, and Non-additivity effects, a method to predict (subcooled liquid pure compound vapour pressure p0 of organic molecules that requires only molecular structure as input. The method is applicable to zero-, mono- and polyfunctional molecules. A simple formula to describe log10p0(T is employed, that takes into account both a wide temperature dependence and the non-additivity of functional groups. In order to match the recent data on functionalised diacids an empirical modification to the method was introduced. Contributions due to carbon skeleton, functional groups, and intramolecular interaction between groups are included. Molecules typically originating from oxidation of biogenic molecules are within the scope of this method: aldehydes, ketones, alcohols, ethers, esters, nitrates, acids, peroxides, hydroperoxides, peroxy acyl nitrates and peracids. Therefore the method is especially suited to describe compounds forming secondary organic aerosol (SOA.

  20. Continuous measurements of isotopic composition of water vapour on the East Antarctic Plateau

    Directory of Open Access Journals (Sweden)

    M. Casado


    Full Text Available Water stable isotopes in central Antarctic ice cores are critical to quantify past temperature changes. Accurate temperature reconstructions require one to understand the processes controlling surface snow isotopic composition. Isotopic fractionation processes occurring in the atmosphere and controlling snowfall isotopic composition are well understood theoretically and implemented in atmospheric models. However, post-deposition processes are poorly documented and understood. To quantitatively interpret the isotopic composition of water archived in ice cores, it is thus essential to study the continuum between surface water vapour, precipitation, surface snow and buried snow. Here, we target the isotopic composition of water vapour at Concordia Station, where the oldest EPICA Dome C ice cores have been retrieved. While snowfall and surface snow sampling is routinely performed, accurate measurements of surface water vapour are challenging in such cold and dry conditions. New developments in infrared spectroscopy enable now the measurement of isotopic composition in water vapour traces. Two infrared spectrometers have been deployed at Concordia, allowing continuous, in situ measurements for 1 month in December 2014–January 2015. Comparison of the results from infrared spectroscopy with laboratory measurements of discrete samples trapped using cryogenic sampling validates the relevance of the method to measure isotopic composition in dry conditions. We observe very large diurnal cycles in isotopic composition well correlated with temperature diurnal cycles. Identification of different behaviours of isotopic composition in the water vapour associated with turbulent or stratified regime indicates a strong impact of meteorological processes in local vapour/snow interaction. Even if the vapour isotopic composition seems to be, at least part of the time, at equilibrium with the local snow, the slope of δD against δ18O prevents us from identifying

  1. Al2O3 coatings against high temperature corrosion deposited by metal-organic low pressure chemical vapour deposition

    NARCIS (Netherlands)

    van Corbach, H.D.; Haanappel, V.A.C.; Haanappel, V.A.C.; Fransen, T.; Gellings, P.J.


    Metal-organic chemical vapour deposition of thin amorphous films of Al2O3 on steels was performed at low pressure. Aluminium tri-sec-butoxide (ATSB) was used as a precursor. The effects of the deposition temperature (200–380 °C), the deposition pressure (0.17–1.20 kPa) and the ATSB concentration

  2. Initial evaluation of airborne water vapour measurements by the IAGOS-GHG CRDS system (United States)

    Filges, Annette; Gerbig, Christoph; Smit, Herman G. J.; Krämer, Martina; Spelten, Nicole


    Accurate and reliable airborne measurements of water vapour are still a challenge. Presently, no airborne humidity sensor exists that covers the entire range of water vapour content between the surface and the upper troposphere/lower stratosphere (UT/LS) region with sufficient accuracy and time resolution. Nevertheless , these data are a pre-requisite to study the underlying processes in the chemistry and physics of the atmosphere. The DENCHAR project (Development and Evaluation of Novel Compact Hygrometer for Airborne Research) addresses this deficit by developing and characterizing novel or improved compact airborne hygrometers for different airborne applications within EUFAR (European Facility for Airborne Research). As part of the DENCHAR inter-comparison campaign in Hohn (Germany), 23 May - 1 June 2011, a commercial gas analyzer (G2401-m, Picarro Inc.,US), based on cavity ring-down spectroscopy (CRDS), was installed on a Learjet to measure water vapour, CO2, CH4 and CO. The CRDS components are identical to those chosen for integration aboard commercial airliner within IAGOS (In-service Aircraft for a Global Observing System). Thus the campaign allowed for the initial assessment validation of the long-term IAGOS H2O measurements by CRDS against reference instruments with a long performance record (FISH, the Fast In-situ Stratospheric Hygrometer, and CR2 frostpoint hygrometer, both research centre Juelich). The inlet system, a one meter long 1/8" FEP-tube connected to a Rosemount TAT housing (model 102BX, deiced) installed on a window plate of the aircraft, was designed to eliminate sampling of larger aerosols, ice particles, and water droplets, and provides about 90% of ram-pressure. In combination with a lowered sample flow of 0.1 slpm (corresponding to a 4 second response time), this ensured a fully controlled sample pressure in the cavity of 140 torr throughout an aircraft altitude operating range up to 12.5 km without the need of an upstream sampling pump

  3. Numerical analysis of the interaction between high-pressure resin spray and wood chips in a vapour stream

    Directory of Open Access Journals (Sweden)

    Massimo Milani


    Full Text Available This article investigates the interaction between the resin spray and the wood chips in a vapour stream using a multi-phase multi-component computational fluid dynamics approach. The interaction between the spray and the chips is one of the main issues in the industrial process for manufacturing medium density fibre boards. Thus, the optimization of this process can lead to important benefits, such as the reduction in the emission of formaldehyde-based toxic chemicals, the reduction in energy consumption in the blending process and energy saving in the fibreboard drying process. First step of the study is the numerical analysis of the resin injector in order to extend the experimental measurements carried out with water to the resin spray. The effects of the injector’s geometrical features on the spray formation are highlighted under different injection pressure values and needle displacements. Afterwards, the results obtained in the analysis of the single injector are used for the complete simulation of multi-injector rail where the mixing of the resin spray and wood chips takes place. The influence of the main operating conditions, such as the vapour and the wood chip flow rates, on the resin distribution is addressed in order to optimize the resination process.

  4. Intercomparison of atmospheric water vapour measurements at a Canadian High Arctic site (United States)

    Weaver, Dan; Strong, Kimberly; Schneider, Matthias; Rowe, Penny M.; Sioris, Chris; Walker, Kaley A.; Mariani, Zen; Uttal, Taneil; McElroy, C. Thomas; Vömel, Holger; Spassiani, Alessio; Drummond, James R.


    Water vapour is a critical component of the Earth system. Techniques to acquire and improve measurements of atmospheric water vapour and its isotopes are under active development. This work presents a detailed intercomparison of water vapour total column measurements taken between 2006 and 2014 at a Canadian High Arctic research site (Eureka, Nunavut). Instruments include radiosondes, sun photometers, a microwave radiometer, and emission and solar absorption Fourier transform infrared (FTIR) spectrometers. Close agreement is observed between all combination of datasets, with mean differences ≤ 1.0 kg m-2 and correlation coefficients ≥ 0.98. The one exception in the observed high correlation is the comparison between the microwave radiometer and a radiosonde product, which had a correlation coefficient of 0.92.A variety of biases affecting Eureka instruments are revealed and discussed. A subset of Eureka radiosonde measurements was processed by the Global Climate Observing System (GCOS) Reference Upper Air Network (GRUAN) for this study. Comparisons reveal a small dry bias in the standard radiosonde measurement water vapour total columns of approximately 4 %. A recently produced solar absorption FTIR spectrometer dataset resulting from the MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) retrieval technique is shown to offer accurate measurements of water vapour total columns (e.g. average agreement within -5.2 % of GRUAN and -6.5 % of a co-located emission FTIR spectrometer). However, comparisons show a small wet bias of approximately 6 % at the high-latitude Eureka site. In addition, a new dataset derived from Atmospheric Emitted Radiance Interferometer (AERI) measurements is shown to provide accurate water vapour measurements (e.g. average agreement was within 4 % of GRUAN), which usefully enables measurements to be taken during day and night (especially valuable during polar night).

  5. Measurement of water vapour transport through a porous non-hygroscopic material in a temperature gradient

    DEFF Research Database (Denmark)

    Hansen, Thor; Padfield, Tim; Hansen, Kurt Kielsgaard


    This was an experiment to identify the driving potential for water vapour diffusion through porous materials in a temperature gradient. The specimen of mineral fibre insulation was placed between a space with controlled temperature and relative humidity and a space with a controlled, higher...... temperature, and a measured but not controlled relative humidity (RH). This assembly was allowed to reach equilibrium with no vapour movement between the spaces, as tested by a constant RH on each side and by zero flux of water vapour measured in the cold side chamber. The RH and temperature values were...... be tested experimentally in this way, but it is reasonable to assume that concentration is the driving potential. The close equality of the concentrations makes it unnecessary to invoke temperature difference as a third possible potential for driving diffusion....

  6. Technical note: Water vapour concentration and flux measurements with PTR-MS

    Directory of Open Access Journals (Sweden)

    C. Ammann


    Full Text Available The most direct approach for measuring the exchange of biogenic volatile organic compounds between terrestrial ecosystems and the atmosphere is the eddy covariance technique. It has been applied several times in the last few years using fast response proton-transfer-reaction mass spectrometry (PTR-MS. We present an independent validation of this technique by applying it to measure the water vapour flux in comparison to a common reference system comprising an infra-red gas analyser (IRGA. Water vapour was detected in the PTR-MS at mass 37 (atomic mass units corresponding to the cluster ion H3O+·H2O. During a five-week field campaign at a grassland site, we obtained a non-linear but stable calibration function between the mass 37 signal and the reference water vapour concentration. With a correction of the high-frequency damping loss based on empirical ogive analysis, the eddy covariance water vapour flux obtained with the PTR-MS showed a very good agreement with the flux of the reference system. The application of the empirical ogive method for high-frequency correction led to significantly better results than using a correction based on theoretical spectral transfer functions. This finding is attributed to adsorption effects on the tube walls that are presently not included in the theoretical correction approach. The proposed high-frequency correction method can also be used for other trace gases with different adsorption characteristics.

  7. Measurement of copper vapour laser-induced deformation of ...

    Indian Academy of Sciences (India)


    Feb 14, 2014 ... This deformation causes a change in interference pattern within the reference interferogram from which the ... From simple error propagation considerations for independent measurement of δP and ... where the smallest measurable fringe shift (δP) is the error (d(δP)) in measuring the same, which is taken ...

  8. Leaf expansion of soybean subjected to high and low atmospheric vapour pressure deficits. (United States)

    Devi, M Jyostna; Taliercio, Earl W; Sinclair, Thomas R


    Vapour pressure deficit (VPD) is considered an important environmental factor that might affect leaf expansion and transpiration rate (TR) in plants. Two slow-wilting soybean (Glycine max (L.) Merr.) genotypes PI 416937 and PI 471938 along with commercial cultivar Hutcheson were subjected to low (1.2-1.6 kPa) and high VPD (2.8-3 kPa) environments to study their leaf expansion and TR over five days. Among the three genotypes, PI 416937 had the lowest increase in its TR (34%) at high VPD compared with low VPD and the greatest decrease in leaf area (31%). In contrast, Hutcheson had the highest increase in TR (87%) under high VPD and the lowest decrease in leaf expansion rate (18%). Expansin and extensin genes were isolated in PI 416937 to determine if changes in leaf expansion were associated with changes at the molecular level. The four studied genes were all suppressed after five days in the high VPD environment. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  9. The role of vapour pressure in multibubble sonoluminescence from organic solvents. (United States)

    Troia, A; Ripa, D Madonna


    The action of high intensity cavitation on several liquid halocarbons (C(2)Cl(4) CCl(4), CHCl(3), C(2)H(2)Br(4)) and other organic solvents (acetone, benzene and their mixtures) was investigated by recording multibubble sonoluminescence UV-Vis spectra over the temperature range between 246 and 298 K. The temperature induced variation of some thermophysical properties of the solvents Favours the interpretations of their role in determining the salient characteristics of the recorded spectra. We observed that high volatility does not necessarily quench sonoluminescence emission and that argon flow plays a key role in the appearance of radical emission lines. While for each investigated substance the intensity of C*(2) emission lines was clearly correlated to temperature, a comparative test between different halocarbons did not show a clear correlation with vapour pressure. Following recently reported results which evidenced the formation of dynamically differentiated populations of emitting bubbles in sulphuric acid, we performed MBSL experiments in liquid mixtures of halocarbons and sulphuric acid to investigate the correlation between the production of emitting species and the halocarbon volatility. Copyright © 2011 Elsevier B.V. All rights reserved.

  10. Evaluation of balloon and satellite water vapour measurements in the Southern tropical and subtropical UTLS during the HIBISCUS campaign

    Directory of Open Access Journals (Sweden)

    N. Montoux


    Full Text Available Balloon water vapour in situ and remote measurements in the tropical upper troposphere and lower stratosphere (UTLS obtained during the HIBISCUS campaign around 20° S in Brazil in February–March 2004 using a tunable diode laser (μSDLA, a surface acoustic wave (SAW and a Vis-NIR solar occultation spectrometer (SAOZ on a long duration balloon, have been used for evaluating the performances of satellite borne remote water vapour instruments available at the same latitude and measurement period. In the stratosphere, HALOE displays the best precision (2.5%, followed by SAGE II (7%, MIPAS (10%, SAOZ (20–25% and SCIAMACHY (35%, all of which show approximately constant H2O mixing ratios between 20–25 km. Compared to HALOE of ±10% accuracy between 0.1–100 hPa, SAGE II and SAOZ show insignificant biases, MIPAS is wetter by 10% and SCIAMACHY dryer by 20%. The currently available GOMOS profiles of 25% precision show a positive vertical gradient in error for identified reasons. Compared to these, the water vapour of the Reprobus Chemistry Transport Model, forced at pressures higher than 95 hPa by the ECMWF analyses, is dryer by about 1 ppmv (20%.

    In the lower stratosphere between 16–20 km, most notable features are the steep degradation of MIPAS precision below 18 km, and the appearance of biases between instruments far larger than their quoted total uncertainty. HALOE and SAGE II (after spectral adjustment for reducing the bias with HALOE at northern mid-latitudes both show decreases of water vapour with a minimum at the tropopause not seen by other instruments or the model, possibly attributable to an increasing error in the HALOE altitude registration. Between 16–18 km where the water vapour concentration shows little horizontal variability, and where the μSDLA balloon measurements are not perturbed by outgassing, the average mixing ratios reported by the remote sensing instruments are substantially lower than the 4–5

  11. Conductive zinc oxide thin film coatings by combustion chemical vapour deposition at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Zunke, I., E-mail: [Innovent e.V. Technology Development, Department of Surface Engineering, Prüssingstr. 27B, 07745 Jena (Germany); Heft, A. [Innovent e.V. Technology Development, Department of Surface Engineering, Prüssingstr. 27B, 07745 Jena (Germany); Schäfer, P.; Haidu, F.; Lehmann, D. [Chemnitz University of Technology, Semiconductor Physics, Reichenhainer Str. 70, 09126 Chemnitz (Germany); Grünler, B.; Schimanski, A. [Innovent e.V. Technology Development, Department of Surface Engineering, Prüssingstr. 27B, 07745 Jena (Germany); Zahn, D.R.T. [Chemnitz University of Technology, Semiconductor Physics, Reichenhainer Str. 70, 09126 Chemnitz (Germany)


    We have established a combustion chemical vapour deposition (C-CVD) system for the deposition of zinc oxide (ZnO) at atmospheric pressure. This C-CVD process has the advantage of a short exposure of the substrates to the flame. It is also potentially applicable as an inline coating system. Fundamental studies were performed on undoped ZnO. The specific resistivity of these layers strongly depends on the film thickness and decreases with increasing thickness. As the lowest resistivities, values of about 2.0 · 10{sup −1} Ωcm are achieved. Ultra-violet photoemission spectra show the valence band structure of the deposited ZnO. The work function and valence band edge were determined. UV–vis spectra were taken to investigate the transmission of the coated glass samples. From these spectra the band gap energy was obtained. Raman spectroscopy as well as infrared spectroscopy confirmed the presence of ordered ZnO crystallites. The X-ray diffraction verified this result and illustrates the hexagonal structure. In the mid-infrared range precursor deposits were detected for low substrate temperatures. - Highlights: ► Zinc oxide (ZnO) films are conductive in the range of 2.0 · 10{sup −1} Ωcm. ► X-ray diffraction, Raman and infrared spectroscopy indicate crystalline ZnO films. ► Precursor deposits were proved within the films for low growing temperatures. ► Band gap energy changes are achieved due to different growing temperatures.

  12. A rate equation model of stomatal responses to vapour pressure deficit and drought

    Directory of Open Access Journals (Sweden)

    Shanahan ST


    Full Text Available Abstract Background Stomata respond to vapour pressure deficit (D – when D increases, stomata begin to close. Closure is the result of a decline in guard cell turgor, but the link between D and turgor is poorly understood. We describe a model for stomatal responses to increasing D based upon cellular water relations. The model also incorporates impacts of increasing levels of water stress upon stomatal responses to increasing D. Results The model successfully mimics the three phases of stomatal responses to D and also reproduces the impact of increasing plant water deficit upon stomatal responses to increasing D. As water stress developed, stomata regulated transpiration at ever decreasing values of D. Thus, stomatal sensitivity to D increased with increasing water stress. Predictions from the model concerning the impact of changes in cuticular transpiration upon stomatal responses to increasing D are shown to conform to experimental data. Sensitivity analyses of stomatal responses to various parameters of the model show that leaf thickness, the fraction of leaf volume that is air-space, and the fraction of mesophyll cell wall in contact with air have little impact upon behaviour of the model. In contrast, changes in cuticular conductance and membrane hydraulic conductivity have significant impacts upon model behaviour. Conclusion Cuticular transpiration is an important feature of stomatal responses to D and is the cause of the 3 phase response to D. Feed-forward behaviour of stomata does not explain stomatal responses to D as feedback, involving water loss from guard cells, can explain these responses.

  13. Growth of Au-catalysed Si nanowires by low pressure chemical vapour deposition on Si(100) and amorphous Si surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Santoni, A; Villacorta, F Jimenez; Rufoloni, A; Mancini, A [ENEA C.R. Frascati, v. E. Fermi 45, I-00044 Frascati (Italy)


    Au-mediated Si nanowires (SiNW) have been grown at low temperatures (500-560 {sup 0}C) on crystalline Si(100) and amorphous Si surfaces by means of low pressure chemical vapour deposition from Si{sub 2}H{sub 6} in the 0.05-1.2 mbar range. The influence of the substrates on the nanowire (NW) growth and morphology has been investigated by means of x-ray photoelectron spectroscopy and scanning electron microscopy. No NW growth has been observed on the Au covered amorphous Si surfaces. On both substrates, the NW exhibit inhomogeneous sidewalls and a new morphology showing NW entrenchment which has been explained as a consequence of vapour-liquid-solid growth termination due to Au diffusion on the SiNW sidewalls.

  14. Novel method for water vapour monitoring using wireless communication networks measurements (United States)

    David, N.; Alpert, P.; Messer, H.


    We propose a new technique for monitoring near-surface water vapour, by estimating humidity from data collected through existing wireless communication networks. Water vapour plays a crucial part in a variety of atmospheric processes. As the most influential of greenhouse gases, it absorbs long-wave terrestrial radiation. The water vapour cycle of evaporation and recondensation is a major energy redistributing mechanism transferring heat energy from the Earth's surface to the atmosphere. Additionally, humidity has an important role in weather forecasting as a key variable required for initialization of atmospheric models and hazard warning techniques. However, current methods of monitoring humidity suffer from low spatial resolution, high cost or a lack of precision when measuring near ground levels. Weather conditions and atmospheric phenomena affect the electromagnetic channel, causing attenuations to the radio signals. Thus, wireless communication networks are in effect built-in environmental monitoring facilities. The wireless microwave links, used in these networks, are widely deployed by cellular providers for backhaul communication between base stations, a few tens of meters above ground level. As a result, the proposed method can provide moisture observations at high temporal and spatial resolution. Further, the implementation cost is minimal, since the data used is already collected and saved by the cellular operators. In addition - many of these links are installed in areas where access is difficult such as orographic terrain and complex topography. As such, our method enables measurements in places that have been hard to measure in the past, or have never been measured before. The technique is restricted to weather conditions which include absence of rain, fog or clouds along the propagation path. We present results from real-data measurements taken from microwave links used in a backhaul cellular network that show very good agreement with surface

  15. Gravimetric phenotyping of whole plant transpiration responses to atmospheric vapour pressure deficit identifies genotypic variation in water use efficiency. (United States)

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


    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. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  16. Properties of alumina films by atmospheric pressure metal-organic chemical vapour deposition

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Haanappel, V.A.C.; van Corbach, H.D.; Fransen, T.; Gellings, P.J.


    Thin alumina films were deposited at low temperatures (290–420°C) on stainless steel, type AISI 304. The deposition process was carried out in nitrogen by metal-organic chemical vapour deposition using aluminum tri-sec-butoxide. The film properties including the protection of the underlying

  17. Measurements of the levels of organic solvent vapours by personal air samplers and the levels of urinary metabolites of workers. Part 2. Toluene vapour in a shipbuilding yard (author's transl). (United States)

    Kira, S


    Personal air samplers were applied to shipyard's painters putting on gas masks during the spraying work, and the levels of toluene vapour surrounding the workers were measured. On the other hand, levels of urinary hippuric acid (metabolites of toluene) of the workers were measured, and the levels of toluene vapour inhaled were calculated from the levels of urinary hippuric acid. Then the actual removing-efficiencies of toluene vapours by the use of gas masks were estimated from these two levels (i.e., toluene vapours exposed and inhaled). The values of removing-efficiencies were found to be 65.9-98.1%. The concentrations of hippuric and methylhippuric acids in the urine of workers exposed to toluene and xylene for 3 hours, collected just after the exposure, are valuable indices of these organic solvent vapours inhaled. A minute amount of urinary methylhippuric acid can be determined by means of gas chromatography.


    Grollman, Arthur


    Data for the depression of vapour pressure are presented for the following aqueous solutions: NaCl (0.03 to 0.1 molar), KCl (0.03 to 0.1 molar), urea (0.05 to 0.5 molar), sucrose (0.05 to 0.10 molar), lactic and succinic acids, creatine, CaCl2 (0.05 molar), and mixtures of these substances with one another and with certain other solutions (gelatin, gum acacia, sea water, LiCl, etc.). The relation of the depression of vapour pressure of a mixed solution to that of solutions of the individual constituents was investigated in order to ascertain to what extent such studies may be used for the determination of the degree of hydration, or of the state of water, in solutions. Organic substances (urea, sucrose, etc.) showed anomalous results which were markedly affected and unpredictable in mixed solutions. They are, therefore, unsuited for the study of water binding. In the case of solutions of inorganic substances—LiCl and CaCl2—the principle of the additive nature of colligative properties is also only approximately true—except perhaps in very dilute solutions. The limitations of the colligative method for determining the degree of hydration have been defined in accord with the above findings. Studies of the vapour pressures of mixtures of gelatin or gum acacia with NaCl or KCl demonstrated that hydration in gelatin is relatively small at pH = 7 and undetectable in gum acacia solutions. The view, therefore, that hydrophilic colloids are strongly hydrated has not been substantiated. The passage from the sol to the gel state also was not accompanied in gelatin or in blood by any appreciable change in the degree of hydration of the hydrophilic colloids present in these substances. PMID:19872614

  19. Vapour pressures, aqueous solubility, Henry's law constants and air/water partition coefficients of 1,8-dichlorooctane and 1,8-dibromooctane. (United States)

    Sarraute, Sabine; Mokbel, Ilham; Costa Gomes, Margarida F; Majer, Vladimir; Delepine, Hervé; Jose, Jacques


    New data on the vapour pressures and aqueous solubility of 1,8-dichlorooctane and 1,8-dibromooctane are reported as a function of temperature between 20 degrees C and 80 degrees C and 1 degrees C and 40 degrees C, respectively. For the vapour pressures, a static method was used during the measurements which have an estimated uncertainty between 3% and 5%. The aqueous solubilities were determined using a dynamic saturation column method and the values are accurate to within +/-10%. 1,8-Dichlorooctane is more volatile than 1,8-dibromooctane in the temperature range covered (p(sat) varies from 3 to 250 Pa and from 0.53 to 62 Pa, respectively) and is also approximately three times more soluble in water (mole fraction solubilities at 25 degrees C of 5.95 x 10(-7) and 1.92 x 10(-7), respectively). A combination of the two sets of data allowed the calculation of the Henry's law constants and the air water partition coefficients. A simple group contribution concept was used to rationalize the data obtained.

  20. Strong low-pass filtering effects on water vapour flux measurements with closed-path eddy correlation systems

    DEFF Research Database (Denmark)

    Ibrom, Andreas; Dellwik, Ebba; Flyvbjerg, Henrik K.


    concentration measurements decreases exponentially with increasing relative humidity. After correction for this unintended filtering, the fluxes are consistent with CO2 and H2O fluxes that were measured with an open-path sensor at the same time. The correction of water vapour flux measurements over a Beech......-pass filtering effects. Other than for CO2 is the magnitude of the correction for water vapour flux measurements unsatisfactorily high, i.e. the EC system needs to be technically improved. Our results suggest that such high correction can be avoided by keeping relative humidity in the entire gas transport system...

  1. Accelerated growth of oxide film on aluminium alloys under steam: Part II: Effects of alloy chemistry and steam vapour pressure on corrosion and adhesion performance

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Bordo, Kirill; Jellesen, Morten Stendahl


    The steam treatment of aluminium alloys with varying vapour pressure of steamresulted in the growth of aluminium oxyhydroxide films of thickness range between 450 - 825nm. The surface composition, corrosion resistance, and adhesion of the produced films was characterised by XPS, potentiodynamic...... polarization, acetic acid salt spray, filiform corrosion test, and tape test. The oxide films formed by steam treatment showed good corrosion resistance in NaCl solution by significantly reducing anodic and cathodic activities. The pitting potential of the surface treated with steam was a function...... of the vapour pressure of the steam. The accelerated corrosion and adhesion tests on steam generated oxide films with commercial powder coating verified that the performance of the oxide coating is highly dependent on the vapour pressure of the steam....

  2. Accelerated growth of oxide film on aluminium alloys under steam: Part I: Effects of alloy chemistry and steam vapour pressure on microstructure

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Gudla, Visweswara C.; Jellesen, Morten S.


    Aluminium alloys were treated with steam of varying vapour pressures which resulted in the growth of aluminium oxyhydroxide layers of an average thickness of ~450–825 nm. The microstructure and composition of the generated layers were characterised by GD-OES, FEG-SEM, GI-XRD and TEM. The thicknes...... of alkaline etching pre-treatment influenced the thickness and growth of theoxide. Moreover the steam treatment resulted in the partial oxidation of second phase intermetallic particles present in the aluminium alloy microstructure....... of the oxide layeras well as the compactness increased with steam vapour pressure. The increase in vapour pressure also resulted in a better coverage over the intermetallic particles. Oxide layer showed a layered structure with more compact layer at the Al interface and a nano-scale needle like structure...

  3. Soil moisture responses to vapour pressure deficit in polytunnel-grown tomato under soil moisture triggered irrigation control (United States)

    Goodchild, Martin; Kühn, Karl; Jenkins, Dick


    The aim of this work has been to investigate soil-to-atmosphere water transport in potted tomato plants by measuring and processing high-resolution soil moisture data against the environmental driver of vapour pressure deficit (VPD). Whilst many researchers have successfully employed sap flow sensors to determine water uptake by roots and transport through the canopy, the installation of sap flow sensors is non-trivial. This work presents an alternative method that can be integrated with irrigation controllers and data loggers that employ soil moisture feedback which can allow water uptake to be evaluated against environmental drivers such as VPD between irrigation events. In order to investigate water uptake against VPD, soil moisture measurements were taken with a resolution of 2 decimal places - and soil moisture, air temperature and relative humidity measurements were logged every 2 minutes. Data processing of the soil moisture was performed in an Excel spread sheet where changes in water transport were derived from the rate of change of soil moisture using the Slope function over 5 soil moisture readings. Results are presented from a small scale experiment using a GP2-based irrigation controller and data logger. Soil moisture feedback is provided from a single SM300 soil moisture sensor in order to regulate the soil moisture level and to assess the water flow from potted tomato plants between irrigation events. Soil moisture levels were set to avoid drainage water losses. By determining the rate of change in soil moisture between irrigation events, over a 16 day period whilst the tomato plant was in flower, it has been possible to observe very good correlation between soil water uptake and VPD - illustrating the link between plant physiology and environmental conditions. Further data is presented for a second potted tomato plant where the soil moisture level is switched between the level that avoids drainage losses and a significantly lower level. This data

  4. Evolution of stratospheric ozone and water vapour time series studied with satellite measurements

    Directory of Open Access Journals (Sweden)

    A. Jones


    Full Text Available The long term evolution of stratospheric ozone and water vapour has been investigated by extending satellite time series to April 2008. For ozone, we examine monthly average ozone values from various satellite data sets for nine latitude and altitude bins covering 60° S to 60° N and 20–45 km and covering the time period of 1979–2008. Data are from the Stratospheric Aerosol and Gas Experiment (SAGE I+II, the HALogen Occultation Experiment (HALOE, the Solar BackscatterUltraViolet-2 (SBUV/2 instrument, the Sub-Millimetre Radiometer (SMR, the Optical Spectrograph InfraRed Imager System (OSIRIS, and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartograpY (SCIAMACHY. Monthly ozone anomalies are calculated by utilising a linear regression model, which also models the solar, quasi-biennial oscillation (QBO, and seasonal cycle contributions. Individual instrument ozone anomalies are combined producing an all instrument average. Assuming a turning point of 1997 and that the all instrument average is represented by good instrumental long term stability, the largest statistically significant ozone declines (at two sigma from 1979–1997 are seen at the mid-latitudes between 35 and 45 km, namely −7.2%±0.9%/decade in the Northern Hemisphere and −7.1%±0.9%/in the Southern Hemisphere. Furthermore, for the period 1997 to 2008 we find that the same locations show the largest ozone recovery (+1.4% and +0.8%/decade respectively compared to other global regions, although the estimated trend model errors indicate that the trend estimates are not significantly different from a zero trend at the 2 sigma level. An all instrument average is also constructed from water vapour anomalies during 1991–2008, using the SAGE II, HALOE, SMR, and the Microwave Limb Sounder (Aura/MLS measurements. We report that the decrease in water vapour values after 2001 slows down around 2004–2005 in the lower tropical stratosphere (20–25 km and has even

  5. Thermodynamic properties of critical clusters from measurements of vapour-liquid homogeneous nucleation rates (United States)

    Ford, I. J.


    Two nucleation theorems are proved using small system thermodynamics. The first is well known and has been used before to determine the number of molecules in the critical nucleus controlling the nucleation of droplets from supersaturated vapours. The second appears to be new, and relates the temperature dependence of the nucleation rate to the excess internal energy of the critical cluster. An analysis of measured homogeneous nucleation rates can therefore provide the size, internal energy, free energy, and entropy of the critical cluster, which should provide important guidance for the construction of theoretical models of the process. This is illustrated using water, n-butanol and n-nonane nucleation data. While there is often a close correspondence between the droplet free energy and the form suggested by classical theory, the excess internal energy seems to show a linear dependence on molecular number, rather than the classical 2/3 power behaviour.

  6. Oxidation of X20 in Water Vapour: The Effect of Temperature and Oxygen Partial Pressure

    DEFF Research Database (Denmark)

    Hansson, Anette Nørgaard; Montgomery, Melanie; Somers, Marcel A. J.


    The oxidation behaviour of X20 in various mixtures of water, oxygen and hydrogen was investigated at temperatures between 500 C and 700 C (time: 336 h). The samples were characterised using reflected light microscopy and scanning electron microscopy equipped with energy dispersive spectroscopy....... Double-layered oxides developed during oxidation under all conditions. The morphology of the oxide layers was strongly influenced by temperature, whereas the influence of the oxidising environment appeared to be less pronounced, as long as it contained water vapour. The inner layer consisted of converted...... M23C6 embedded in Fe–Cr spinel after oxidation at 500 and 600 C, while alternating layers of Cr-rich and Cr-poor oxide were observed after oxidation at 700 C. An internal oxidation zone developed during oxidation at 500 and 600 C, with its depth influenced by the oxidising environments. The results...

  7. Structural characterisation of silicon-germanium virtual substrate- based heterostructures grown by low pressure chemical vapour deposition

    CERN Document Server

    Mihai-Dilliway, G D


    Silicon-germanium heterostructures incorporating compositionally graded virtual substrates are important for the fabrication of a variety of advanced electronic devices. Their successful application depends critically on their surface morphology and defect content. The aim of this research project is to characterise the way in which these structural properties are influenced by the growth parameters used in low pressure chemical vapour deposition (LPCVD) at the Southampton University Microelectronics Centre (SUMC). To this end, a comparative study of the surface quality and the distribution and density of misfit strain relaxation induced defects in SiGe virtual substrate-based heterostructures grown under varying conditions, was carried out. The growth parameters varied have been: growth temperature, initial and final Ge content, Ge concentration gradient, type of Ge grading profile (linear and stepwise) in the virtual substrate, and thickness and presence of a device structure in the capping layer of constan...

  8. The epidermal resistance to diffusion of water vapour : an improved measuring method and field results in Indian corn (Zea mays)

    NARCIS (Netherlands)

    Stigter, C.J.


    The resistance of the epidermis of the leaf to diffusion of water vapour can be measured most accurately in the field by closed diffusion porometers. It was possible to overcome the problems related to calibration and to dynamical use of a LiCl humidity sensor in the porometer. The dynamic behaviour

  9. The kinetics of swelling in block copolymer thin films during ``solvo-microwave'' and solvo-thermal annealing: The effect of vapour pressure (United States)

    Mokarian-Tabari, Parvanrh; Collins, Timothy; Cummins, Cian; Delgado Simão, Claudia; Sotomayor, Clivia; Morris, Michael A.


    Long annealing time associated with high chi block copolymers is a major disadvantage for their integration in industrial applications. Microwave-assisted microphase separation appears to offer considerable benefits in reducing annealing times for BCPs. However, despite the promise of this technique, little is known about the mechanism of how microwave irradiation might sponsor the molecular motion that accompanies microphase separation. In our earlier work we carried out an in situ temperature measurement during ``solvo-microwave'' annealing of poly(styrene-b-lactic acid) (PS- b-PLA) in presence of THF and also in the conventional oven. Comparing the results indicated that vapour pressure of THF might have a major role to achieve fast self- assembly (60 seconds) in PS- b-PLA film. Here, we study the kinetics of swelling by monitoring the pressure through in situ pressure experiments during ``solvo-microwave'' and solvo-thermal annealing. The preliminary data suggest that the rate at which the THF pressure increases is the key factor. This suggests that kinetics, i.e., the rate of film swelling and diffusion, affects the order and the coherence length of the pattern. We estimated the defect density in the patterns by our recently developed defect analysis software.

  10. Continuous quality assessment of atmospheric water vapour measurement techniques: FTIR, Cimel, MFRSR, GPS, and Vaisala RS92

    Directory of Open Access Journals (Sweden)

    M. Schneider


    Full Text Available At the Izaña Observatory, water vapour amounts have been measured routinely by different techniques for many years. We intercompare the total precipitable water vapour (PWV amounts measured between 2005 and 2009 by a Fourier Transform Infrared (FTIR spectrometer, a Multifilter Rotating Shadow-band Radiometer (MFRSR, a Cimel sunphotometer, a Global Positioning System (GPS receiver, and daily radiosondes (Vaisala RS92. The long-term characteristics of our study allows a reliable and extensive empirical quality assessment of long-term validity, which is an important prerequisite when applying the data to climate research. We estimate a PWV precision of 1% for the FTIR, about 10% for the MFRSR, Cimel, and GPS (when excluding rather dry conditions, and significantly better than 15% for the RS92 (the detection of different airmasses avoids a better constrained estimation. We show that the MFRSR, Cimel and GPS data quality depends on the atmospheric conditions (humid or dry and that the restriction to clear-sky observations introduces a significant dry bias in the FTIR and Cimel data. In addition, we intercompare the water vapour profiles measured by the FTIR and the Vaisala RS92, which allows the conclusion that both experiments are able to detect lower to upper tropospheric water vapour mixing ratios with a precision of better than 15%.

  11. Properties of alumina films prepared by metal-organic chemical vapour deposition at atmospheric pressure in hte presence of small amounts of water

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Haanappel, V.A.C.; van Corbach, H.D.; Rem, J.B.; Fransen, T.; Gellings, P.J.


    Thin alumina films were deposited on stainless steel, type AISI 304. The deposition process was carried out in nitrogen with low partial pressures of water (0–2.6 × 10−2 kPa (0−0.20 mmHg)) by metal-organic chemical vapour deposition (MOCVD) with aluminium-tri-sec-butoxide (ATSB) as the precursor.

  12. Gas permeation measurement under defined humidity via constant volume/variable pressure method

    KAUST Repository

    Jan Roman, Pauls


    Many industrial gas separations in which membrane processes are feasible entail high water vapour contents, as in CO 2-separation from flue gas in carbon capture and storage (CCS), or in biogas/natural gas processing. Studying the effect of water vapour on gas permeability through polymeric membranes is essential for materials design and optimization of these membrane applications. In particular, for amine-based CO 2 selective facilitated transport membranes, water vapour is necessary for carrier-complex formation (Matsuyama et al., 1996; Deng and Hägg, 2010; Liu et al., 2008; Shishatskiy et al., 2010) [1-4]. But also conventional polymeric membrane materials can vary their permeation behaviour due to water-induced swelling (Potreck, 2009) [5]. Here we describe a simple approach to gas permeability measurement in the presence of water vapour, in the form of a modified constant volume/variable pressure method (pressure increase method). © 2011 Elsevier B.V.

  13. Latent heat flux measurements over complex terrain by airborne water vapour and wind lidars

    National Research Council Canada - National Science Library

    Kiemle, Christoph; Wirth, Martin; Fix, Andreas; Rahm, Stephan; Corsmeier, Ulrich; Di Girolamo, Paolo


    Vertical profiles of the latent heat flux in a convective boundary layer (CBL) are obtained for the first time over complex terrain with airborne water vapour differential absorption lidar and Doppler wind lidar...

  14. Measurements of mesospheric water vapour, aerosols and temperatures with the Spectral Absorption Line Imager (SALI-AT) (United States)

    Shepherd, M. G.; Mullins, M.; Brown, S.; Sargoytchev, S. I.


    Water vapour concentration is one of the most important, yet one of the least known quantities of the mesosphere. Knowledge of water vapour concentration is the key to understanding many mesospheric processes, including the one that is primary focus of our investigation, mesospheric clouds (MC). The processes of formation and occurrence parameters of MC constitute an interesting problem in their own right, but recently evidence has been provided which suggests that they are a critical indicator of atmospheric change. The aim of the SALI-AT experiment is to make simultaneous (although not strictly collocated) measurements of water vapour, aerosols and temperature in the mesosphere and the mesopause region under twilight condition in the presence of mesospheric clouds. The water vapour will be measured in the regime of solar occultation utilizing a water vapour absorption band at 936 nm wavelength employing the SALI (Spectral Absorption Line Imager) instrument concept. A three-channel zenith photometer, AT-3, with wavelengths of 385 nm, 525 nm, and 1040 nm will measure Mie and Rayleigh scattering giving both mesospheric temperature profiles and the particle size distribution. Both instruments are small, low cost and low mass. It is envisioned that the SALI-AT experiment be flown on a small rocket - the Improved Orion/Hotel payload configuration, from the Andoya Rocket range, Norway. Alternatively the instrument can be flown as a "passenger" on larger rocket carrying other experiments. In either case flight costs are relatively low. Some performance simulations are presented showing that the instrument we have designed will be sufficiently sensitive to measure water vapor in concentrations that are expected at the summer mesopause, about 85 km height.

  15. A Rapid Deposition of Fluorine Doped Zinc Oxide Using the Atmospheric Pressure Chemical Vapour Deposition Method (United States)

    Najafi, Navid; Rozati, S. M.


    Fluorine-doped zinc oxide (FZO) (ZnO:F) thin films were manufactured by atmospheric pressure chemical vapor deposition (APCVD) on glass substrates using zinc acetate dihydrate [C4H6O4Zn·2H2O, ZnAc] and ammonium fluoride (NH4F) as the source of fluorine with deposition duration of only 120 s for each sample. The effects of different amounts of fluorine as the dopant on the structural, electrical and optical properties of FZO thin films were investigated. The results show a polycrystalline structure at higher temperatures compared to amorphous structure at lower temperatures. The x-ray diffraction patterns of the polycrystalline films were identified as a hexagonal wurtzite structure of zinc oxide (ZnO) with the (002) preferred orientation. Also, the sheet resistance decreased from 17.8 MΩ/□ to 28.9 KΩ/□ for temperatures 325°C to 450°C, respectively. In order to further decrease the sheet resistance of the undoped ZnO thin films, fluorine was added using NH4F as the precursor, and again a drastic change in sheet resistance of only 17.7 Ω/□ was obtained. Based on the field emission scanning electron microscopy images, the fluorine concentration in CVD source is an important factor affecting the grain size and modifies electrical parameters. Ultraviolet-visible measurements revealed reduction of transparency of the layers with increasing fluorine as the dopant.

  16. A Rapid Deposition of Fluorine Doped Zinc Oxide Using the Atmospheric Pressure Chemical Vapour Deposition Method (United States)

    Najafi, Navid; Rozati, S. M.


    Fluorine-doped zinc oxide (FZO) (ZnO:F) thin films were manufactured by atmospheric pressure chemical vapor deposition (APCVD) on glass substrates using zinc acetate dihydrate [C4H6O4Zn·2H2O, ZnAc] and ammonium fluoride (NH4F) as the source of fluorine with deposition duration of only 120 s for each sample. The effects of different amounts of fluorine as the dopant on the structural, electrical and optical properties of FZO thin films were investigated. The results show a polycrystalline structure at higher temperatures compared to amorphous structure at lower temperatures. The x-ray diffraction patterns of the polycrystalline films were identified as a hexagonal wurtzite structure of zinc oxide (ZnO) with the (002) preferred orientation. Also, the sheet resistance decreased from 17.8 MΩ/□ to 28.9 KΩ/□ for temperatures 325°C to 450°C, respectively. In order to further decrease the sheet resistance of the undoped ZnO thin films, fluorine was added using NH4F as the precursor, and again a drastic change in sheet resistance of only 17.7 Ω/□ was obtained. Based on the field emission scanning electron microscopy images, the fluorine concentration in CVD source is an important factor affecting the grain size and modifies electrical parameters. Ultraviolet-visible measurements revealed reduction of transparency of the layers with increasing fluorine as the dopant.

  17. Technical Note: How accurate can stalagmite formation temperatures be determined using vapour bubble radius measurements in fluid inclusions?

    DEFF Research Database (Denmark)

    Spadin, F.; Marti, Dominik; Hidalgo-Staub, R.


    -induced vapour bubbles inside the inclusions. A reliable method for precisely measuring the radius of vapour bubbles is presented. The method is applied to stalagmite samples for which the formation temperature is known. An assessment of the bubble radius measurement accuracy and how this error influences......Stalagmites are natural archives containing detailed information on continental climate variability of the past. Microthermometric measurements of fluid inclusion homogenisation temperatures allow determination of stalagmite formation temperatures by measuring the radius of stable laser...... the uncertainty in determining the formation temperature is provided. We demonstrate that the nominal homogenisation temperature of a single inclusion can be determined with an accuracy of ±0.25 ◦C, if the volume of the inclusion is larger than 105 µm3 . With this method, we could measure in a proof...

  18. Observation of a physical matrix effect during cold vapour generation measurement of mercury in emissions samples. (United States)

    Brown, Richard J C; Webb, William R; Goddard, Sharon L


    The observation of a physical matrix effect during the cold vapour generation-atomic fluorescence measurement of mercury in emissions samples is reported. The effect is as a result of the different efficiencies of liberation of reduced mercury from solution as the matrix of the solution under test varies. The result of this is that peak area to peak height ratios decease as matrix concentration increases, passing through a minimum, before the ratio then increases as matrix concentration further increases. In the test matrices examined - acidified potassium dichromate and sodium chloride solutions - the possible biases caused by differences between the calibration standard matrix and the test sample matrix were as large as 2.8% (relative) representing peak area to peak height ratios for calibration standards and matrix samples of 45 and 43.75, respectively. For the system considered there is a good correlation between the density of the matrix and point of optimum liberation of dissolved mercury for both matrix types. Several methods employing matrix matching and mathematical correction to overcome the bias are presented and their relative merits discussed; the most promising being the use of peak area, rather than peak height, for quantification. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. A lidar for water vapour measurements in daytime at Lampedusa, Italy

    Directory of Open Access Journals (Sweden)

    F. Marenco


    Full Text Available ENEA is planning to develop a lidar system for measurement of the vertical profi le of water vapour mixing ratio in daytime at a remote site, the Station for Climate Observations located in Lampedusa, Italy. The Raman lidar technique has been retained because of its experimental simplicity with respect to DIAL, and the UV spectral range has been chosen because Raman cross-sections and detector effi ciencies are larger. For a wavelength larger than ~ 300 nm the signal is limited in daytime by sky background, but extinction is acceptable, and the aims of the system can be reached with a strong laser source. The 355 nm wavelength of a frequency-tripled Nd:YAG laser has been retained as this laser source permits to reach a large pulse energy while keeping the system simple to operate. Geometrical form factor calculations need to be performed to evaluate the near-range overlap between the laser beam and the fi eld-of-view of the receiver. Among several options, a dual-receiver system has been retained to account for the several orders of magnitude expected in the backscattered signal intensity: a smaller receiver, with a primary mirror of 200 mm diameter for the 0.2-1 km range, and a larger 500 mm receiver for the 1-3 km range.

  20. Technical Note: Novel method for water vapour monitoring using wireless communication networks measurements

    Directory of Open Access Journals (Sweden)

    N. David


    Full Text Available We propose a new technique that overcomes the obstacles of the existing methods for monitoring near-surface water vapour, by estimating humidity from data collected through existing wireless communication networks.

    Weather conditions and atmospheric phenomena affect the electromagnetic channel, causing attenuations to the radio signals. Thus, wireless communication networks are in effect built-in environmental monitoring facilities. The wireless microwave links, used in these networks, are widely deployed by cellular providers for backhaul communication between base stations, a few tens of meters above ground level. As a result, if all available measurements are used, the proposed method can provide moisture observations with high spatial resolution and potentially high temporal resolution. Further, the implementation cost is minimal, since the data used are already collected and saved by the cellular operators. In addition – many of these links are installed in areas where access is difficult such as orographic terrain and complex topography. As such, our method enables measurements in places that have been hard to measure in the past, or have never been measured before. The technique is restricted to weather conditions which exclude rain, fog or clouds along the propagation path. Strong winds that may cause movement of the link transmitter or receiver (or both may also interfere with the ability to conduct accurate measurements.

    We present results from real-data measurements taken from two microwave links used in a backhaul cellular network that show convincing correlation to surface station humidity measurements. The measurements were taken daily in two sites, one in northern Israel (28 measurements, the other in central Israel (29 measurements. The correlation between the microwave link measurements and the humidity gauges were 0.9 and 0.82 for the north and central sites, respectively. The Root Mean Square Differences

  1. Effect of dispersive long-range corrections to the pressure tensor: The vapour-liquid interfacial properties of the Lennard-Jones system revisited

    Energy Technology Data Exchange (ETDEWEB)

    Martínez-Ruiz, F. J.; Blas, F. J., E-mail: [Departamento de Física Aplicada, Universidad de Huelva, 21071 Huelva (Spain); Centro de Investigación de Física Teórica y Matemática, Universidad de Huelva, 21071 Huelva (Spain); Mendiboure, B. [Laboratoire des Fluides Complexes et leurs Réservoirs, UMR5150, Université de Pau et des Pays de l’Adour, B. P. 1155, Pau Cedex 64014 (France); Moreno-Ventas Bravo, A. I. [Centro de Investigación de Física Teórica y Matemática, Universidad de Huelva, 21071 Huelva (Spain); Departamento de Geología, Facultad de Ciencias Experimentales, Universidad de Huelva, 21071 Huelva (Spain)


    We propose an extension of the improved version of the inhomogeneous long-range corrections of Janeček [J. Phys. Chem. B 110, 6264–6269 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] to account for the intermolecular potential energy of spherical, rigid, and flexible molecular systems, to deal with the contributions to the microscopic components of the pressure tensor due to the dispersive long-range corrections. We have performed Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of spherical Lennard-Jones molecules with different cutoff distances, r{sub c} = 2.5, 3, 4, and 5σ. In addition, we have also considered cutoff distances r{sub c} = 2.5 and 3σ in combination with the inhomogeneous long-range corrections proposed in this work. The normal and tangential microscopic components of the pressure tensor are obtained using the mechanical or virial route in combination with the recipe of Irving and Kirkwood, while the macroscopic components are calculated using the Volume Perturbation thermodynamic route proposed by de Miguel and Jackson [J. Chem. Phys. 125, 164109 (2006)]. The vapour-liquid interfacial tension is evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the Test-Area methodology. In addition to the pressure tensor and the surface tension, we also obtain density profiles, coexistence densities, vapour pressure, critical temperature and density, and interfacial thickness as functions of temperature, paying particular attention to the effect of the cutoff distance and the long-range corrections on these properties. According to our results, the main effect of increasing the cutoff distance (at fixed temperature) is to sharpen the vapour-liquid interface, to decrease the vapour pressure, and to increase the width of the biphasic coexistence region. As a result, the interfacial

  2. Atomic fluorescence emitted from a corona discharge in helium above and below saturated vapour pressure (United States)

    Shiltagh, Nagham M.; Mendoza Luna, Luis G.; Watkins, Mark J.; Thornton, Stuart C.; von Haeften, Klaus


    A new apparatus was constructed to investigate the visible and near infrared fluorescence spectroscopy of electronically excited helium over a wide range of pressures and temperatures, covering both the gaseous and liquid phases. To achieve sufficient throughput, increased sensitivity was established by employing a micro-discharge cell and a high performance lens system that allows for a large collection solid angle. With this set-up, several thousand spectra were recorded. The atomic 3 s 1 S → 2 p 1 P and 3 s 3 S → 2 p 3 P atomic transitions showed line shifts, spectral broadening and intensity changes that were dependent in magnitude on pressure, temperature and thermodynamic phase. While in the gas phase the lines showed little dependency on the discharge cell temperature, the opposite was observed for the liquid phase, suggesting that a significant number of atoms were solvated. Triplet lines were up to a factor of 50 times stronger in intensity than the singlet lines, depending on pressure. When taking the particle density into account, this effect was stronger in the gas phase than in the liquid phase of helium. This was attributed to the recombination of He2 +, He3 + and He4 + with electrons, which is facilitated in the gas phase because of the significantly higher mobility.

  3. On the representativity of water vapour measurements at Boulder for global stratospheric trends (United States)

    Lossow, S.


    Long-term changes of water vapour in the lower stratosphere inevitably affect the surface climate. Thus understanding such changes is of primary importance. The longest continuous data set is based on balloon-borne frost point hygrometer observations at Boulder. Overall this data set shows an increase in water vapour since the 1980s accompanied by large variability on short time scales (Hurst et al., 2011). Recently a merged satellite data set, covering the time period between 1988 and 2010, has been analysed showing a decrease of water vapour in the lower stratosphere (Hegglin et al., 2014). This discrepancy is difficult to reconcile. There might be problems with one data set or even with both. Also the local behaviour at Boulder might not be representative for the zonal mean behaviour, which is represented by the satellite observations. So far this has been assumed and the Boulder changes have even been considered to be globally representative. Here I present investigations of this aspect using both model simulations and observations. References: Hegglin et al. (2014), "Vertical structure of stratospheric water vapour trends derived from merged satellite data", Nature Geoscience, 7, 768 - 776, doi:10.1038/ngeo2236. Hurst et al. (2011), "Stratospheric water vapor trends over Boulder, Colorado: Analysis of the 30 year Boulder record", Journal of Geophysical Research, 116, D02,306, doi:10.1029/2010JD015065.

  4. Water vapour emission in vegetable fuel: absorption cell measurements and detection limits of our CO II Dial system (United States)

    Bellecci, C.; De Leo, L.; Gaudio, P.; Gelfusa, M.; Lo Feudo, T.; Martellucci, S.; Richetta, M.


    Forest fires can be the cause of serious environmental and economic damages. For this reason a considerable effort has been directed toward the forest protection and fire fighting. In the early forest fire detection, Lidar technique present considerable advantages compared to the passive detection methods based on infrared cameras currently in common use, due its higher sensitivity and ability to accurately locate the fire. The combustion phase of the vegetable matter causes a great amount of water vapour emission, thus the water molecule behaviour will be studied to obtain a fire detection system ready and efficient also before the flame propagation. A first evaluation of increment of the water vapour concentration compared to standard one will be estimated by a numerical simulation. These results will be compared with the experimental measurements carried out into a cell with a CO II Dial system, burning different kinds of vegetable fuel. Our results and their comparison will be reported in this paper.

  5. Experimental evaluation of water vapour cross-sensitivity for accurate eddy covariance measurement of CO2 flux using open-path CO2/H2O gas analysers

    Directory of Open Access Journals (Sweden)

    Fumiyoshi Kondo


    Full Text Available Non-dispersive infrared CO2/H2O gas analysers produce erroneous CO2 outputs when CO2 is measured in humid air, unless a correction for water vapour cross-sensitivity is applied. Spectroscopic cross-sensitivities arising from direct absorption interference and from the pressure broadening effect are significant in CO2 flux measurements by the eddy covariance technique using open-path gas analysers over the ocean, as opposed to land-surface measurements, where CO2 fluxes are orders of magnitude larger. In this study, a widely used analyser with manufacturer-determined correction coefficients for both cross-sensitivities was tested by laboratory experiments. Our results showed that the correction coefficient for direct absorption interference was not optimised to calculate CO2 flux accurately, and that the correction coefficient for the pressure broadening caused overestimation of the CO2 mixing ratio flux in the same direction as the water vapour flux. Overestimations of open-path eddy covariance measurements of upward CO2 fluxes in previous ocean observations probably resulted from inaccuracies in both of these correction coefficients. We also found that slight changes in spectroscopic cross-sensitivities due to contamination of the analyser's optical windows by sea salt caused a low bias in CO2 outputs with increasing H2O; however, this contamination effect was not always observed in repeated tests under different contamination conditions. We suggest that previously proposed methods for correcting the effect of optical window contamination is of limited value and that measurement of small CO2 fluxes by the open-path eddy covariance technique over the ocean should be performed after confirming the spectroscopic cross-sensitivity and ensuring that the optical windows are as clean as possible.

  6. Technical Note: Improved total atmospheric water vapour amount determination from near-infrared filter measurements with sun photometers

    Directory of Open Access Journals (Sweden)

    F. Mavromatakis


    Full Text Available In this work we explore the effect of the contribution of the solar spectrum to the recorded signal in wavelengths outside the typical 940-nm filter's bandwidth. We employ gaussian-shaped filters as well as actual filter transmission curves, mainly AERONET data, to study the implications imposed by the non-zero out-of-band contribution to the coefficients used to derive precipitable water from the measured water vapour band transmittance. Published parameterized transmittance functions are applied to the data to determine the filter coefficients. We also introduce an improved, three-parameter, fitting function that can describe the theoretical data accurately, with significantly less residual effects than with the existing functions. The moderate-resolution SMARTS radiative transfer code is used to predict the incident spectrum outside the filter bandpass for different atmospheres, solar geometries and aerosol optical depths. The high-resolution LBLRTM radiative transfer code is used to calculate the water vapour transmittance in the 940-nm band. The absolute level of the out-of-band transmittance has been chosen to range from 10−6 to 10−4, and typical response curves of commercially available silicon photodiodes are included into the calculations.

    It is shown that if the out-of-band transmittance effect is neglected, as is generally the case, then the derived columnar water vapour is mainly underestimated by a few percents. The actual error depends on the specific out-of-band transmittance, optical air mass of observation and water vapour amount. Further investigations will use experimental data from field campaigns to validate these findings.

  7. Microwave measurements of temperature profiles, integrated water vapour, and liquid water path at Thule Air Base, Greenland. (United States)

    Pace, Giandomenico; Di Iorio, Tatiana; di Sarra, Alcide; Iaccarino, Antonio; Meloni, Daniela; Mevi, Gabriele; Muscari, Giovanni; Cacciani, Marco


    A RPG Humidity And Temperature PROfiler (HATPRO-G2 ) radiometer was installed at Thule Air Base (76.5° N, 68.8° W), Greenland, in June 2016 in the framework of the Study of the water VApour in the polar AtmosPhere (SVAAP) project. The Danish Meteorological Institute started measurements of atmospheric properties at Thule Air Base in early '90s. The Thule High Arctic Atmospheric Observatory (THAAO) has grown in size and observing capabilities during the last three decades through the international effort of United States (NCAR and University of Alaska Fairbanks) and Italian (ENEA, INGV, University of Roma and Firenze) institutions ( Within this context, the intensive field campaign of the SVAAP project was aimed at the investigation of the surface radiation budget and took place from 5 to 28 July, 2016. After the summer campaign the HATPRO has continued to operate in order to monitor the annual variability of the temperature profile and integrated water vapour as well as the presence and characteristics of liquid clouds in the Artic environment. The combined use of the HATPRO together with other automatic instruments, such as a new microwave spectrometer (the water Vapour Emission Spectrometer for Polar Atmosphere VESPA-22), upward- and downward-looking pyranometers and pyrgeometers, a zenith-looking pyrometer operating in the 9.6-11.5 µm spectral range, an all sky camera, and a meteorological station, allows to investigate the clouds' physical and optical properties, as well as their impact on the surface radiation budget. This study will present and discuss the first few months of HATPRO observations; the effectiveness of the statistical retrieval used to derive the physical parameters from the HATPRO brightness temperatures will also be investigated through the comparison of the temperature and humidity profiles, and integrated water vapour, with data from radiosondes launched during the summer campaign and in winter time.

  8. Photosynthetic traits of five neotropical rainforest tree species: interactions between light response curves and leaf-to-air vapour pressure deficit

    Directory of Open Access Journals (Sweden)

    Marcelo Schramm Mielke


    Full Text Available Measurements of leaf gas exchange at different photosynthetic photon flux density (PPFD levels were conducted in order to compare the photosynthetic traits of five neotropical rainforest tree species, with a special emphasis on empirical mathematical models to estimate the light response curve parameters incorporating the effects of leaf-to-air vapour pressure deficit (D on the saturated photosynthetic rate (Amax. All empirical mathematical models seemed to provide a good estimation of the light response parameters. Comparisons of the leaf photosynthetic traits between different species needed to select an appropriate model and indicated the microenvironmental conditions when the data were collected. When the vapour pressure deficit inside the chamber was not controlled, the incorporation of linear or exponencial functions that explained the effects of D on leaf gas exchange, was a very good method to enhance the performance of the models.Medições das trocas gasosas foliares em diferentes níveis do densidade de fluxo de fótons fotossintéticamente ativos (PPFD foram realizadas com o objetivo de comparar as características fotossintéticas de cinco espécies arbóreas de florestas úmidas neotropicais, com especial ênfase em modelos matemáticos empíricos para estimativa de parâmetros derivados das curvas de resposta à radiação luminosa e dos efeitos da diferença de pressão de vapor entre a folha e o ar (D na taxa fotossintética em saturação luminosa (Amax. Os modelos analisados proporcionaram boas estimativas para os parâmetros derivados das curvas de resposta à radiação luminosa. Comparações entre as características fotossintéticas de diferentes espécies devem sempre considerar os modelos utilizados, seguidas de indicações pormenorizadas das condições microambientais no momento em que os dados foram coletados. Quando a diferença de pressão de vapor não for controlada artificialmente durante as medições, a

  9. Vapour-liquid equilibrium of nitrogen-oxygen mixtures and air at high pressure (United States)

    Rainwater, J. C.; Jacobsen, R. T.


    The vapor-liquid equilibrium surface of the binary mixture nitrogen-oxygen is correlated over an extended critical region with the Leung-Griffiths model as modified by Rainwater and Moldover (1983). No single comprehensive experimental measurement of the coexistence surface is available. However, several different experiments along isopleths, isotherms, and isobars collectively provide enough data to make possible the development of a reasonable correlation. The model is optimized to modern data and is shown to be consistent with pioneering measurements done before 1930, to within experimental and temperature-scale uncertainties. It is shown that air in the critical region can be accurately modeled as a nitrogen-oxygen binary mixture by including the small argon component with oxygen. Ancillary equations for the saturation properties of air as functions of temperature are also constructed.

  10. A Battery Powered Highly Efficient Exterior Lighting System Using Low Pressure Sodium Vapour Lamp for Use in Non-electrified Areas (United States)

    Ray, Kalyankumar; Golder, Sujit; Mazumdar, Saswati

    Innumerous attempts to solve the problems of exterior lighting in non-electrified areas of India e.g. highways, hilly areas, rural areas of delta regions have been made in the last two decades. A solar powered lighting system with 11 watt or 18 watt Compact Fluorescent Lamps (CFL) have been mounted in street light fixtures at some places but insufficient amount of light do not always serve the required need of the users specially in foggy weather. This paper reports the development of a battery powered lighting system fitted with a 35 Watt Low Pressure Sodium Vapour (SOX) lamp. It is extremely beneficial in remote non-electrified areas for its far higher light output when fitted in street light or flood light fixtures. The battery may be charged from any non-conventional energy source and is connected to the electronic circuit, which operates at high frequency. The light output of this system fitted with a solar photovoltaic array (SPVA) and the corresponding battery power have been measured and the results have been reported in this paper. This high intensity lighting system has a wide application potential in developing countries throughout the world.

  11. Persistent negative temperature response of mesophyll conductance in red raspberry (Rubus idaeus L.) leaves under both high and low vapour pressure deficits: a role for abscisic acid? (United States)

    Qiu, Changpeng; Ethier, Gilbert; Pepin, Steeve; Dubé, Pascal; Desjardins, Yves; Gosselin, André


    The temperature dependence of mesophyll conductance (gm ) was measured in well-watered red raspberry (Rubus idaeus L.) plants acclimated to leaf-to-air vapour pressure deficit (VPDL) daytime differentials of contrasting amplitude, keeping a fixed diurnal leaf temperature (Tleaf ) rise from 20 to 35 °C. Contrary to the great majority of gm temperature responses published to date, we found a pronounced reduction of gm with increasing Tleaf irrespective of leaf chamber O2 level and diurnal VPDL regime. Leaf hydraulic conductance was greatly enhanced during the warmer afternoon periods under both low (0.75 to 1.5 kPa) and high (0.75 to 3.5 kPa) diurnal VPDL regimes, unlike stomatal conductance (gs ), which decreased in the afternoon. Consequently, the leaf water status remained largely isohydric throughout the day, and therefore cannot be evoked to explain the diurnal decrease of gm . However, the concerted diurnal reductions of gm and gs were well correlated with increases in leaf abscisic acid (ABA) content, thus suggesting that ABA can induce a significant depression of gm under favourable leaf water status. Our results challenge the view that the temperature dependence of gm can be explained solely from dynamic leaf anatomical adjustments and/or from the known thermodynamic properties of aqueous solutions and lipid membranes.​. © 2017 John Wiley & Sons Ltd.

  12. Carbon and oxygen isotope ratios in wood constituents of Pinus halepensis as indicators of precipitation, temperature and vapour pressure deficit

    Energy Technology Data Exchange (ETDEWEB)

    Ferrio, J.P.; Voltas, J. [E.T.S.E.A.-Universitat de Lleida (Spain). Dept. de Produccio Vegetal i Ciencia Forestal


    Carbon and oxygen isotope compositions ({delta}{sup 13}C, {delta}{sup 18}O) in tree rings have been shown to bear relevant climatic signals. However, little is known about the interrelationship between both isotopes in wood constituents for species from other than relatively wet climates. We hypothesized that in a species adapted to temporary droughts (e.g. Pinus halepensis Mill.) the signal derived from {delta}{sup 18}O in precipitation would be hidden by the strong variability in leaf transpirative enrichment. To test this assumption, we compared the effect of precipitation, temperature and vapour pressure deficit (VPD) on {delta}{sup 18}O and {delta}{sup 13}C along 23 sites covering the ecological range for this species. We extracted the cores from the south side of four to six adult dominant trees per aspect (north/south) within each site. For each aspect and site, fragments of the period 1975-1999 were pooled and milled to a fine powder. To further test the postulated need for cellulose purification in the assessment of climatic information, we studied these relationships in whole and extracted wood, holocellulose and lignin. In all wood fractions, {delta}{sup 13}C was related to annual precipitation [r=0.58 (P< 0.01) to 0.78 (P< 0.001)] and VPD [r=0.53 (P< 0.01) to 0.57 (P< 0.01)]. In contrast, for {delta}{sup 18}O only holocellulose showed consistent relationships with climatic data, being strongly significant for VPD [r=0.66 (P< 0.001)]. However, it was unrelated to modelled {delta}{sup 18}O in precipitation, confirming that transpirative enrichment (driven by VPD) dampened the source signal in P. halepensis. The relationships between {delta}{sup 13}C and {delta}{sup 18}O were generally poor, regardless of the wood constituent, suggesting that although both variables were somewhat related to transpirative demand, they were relatively independent. This was further confirmed by building stepwise models using both isotopes to predict annual and seasonal

  13. Low vapour pressure deficit reduces the beneficial effect of elevated CO{sub 2} on growth of N{sub 2}-fixing alfalfa plants

    Energy Technology Data Exchange (ETDEWEB)

    Luis, I. De; Irigoyen, J.J.; Sanchez-Diaz, M. [Univ. de Navarra, Dept. de Fisioligia Vegetal, Pamplona (Spain)


    Plant responses to elevated CO{sub 2} can be modified by many environmental factors, but very little attention has been paid to the interaction between CO{sub 2} and changes in vapour pressure deficit (VPD). Thirty-day-old alfalfa plants (Medicago sativa L. cv. Aragon), which were inoculated with Sinorhizobium meliloti 102F78 strain, were grown for 1 month in controlled environment chambers at 25/15 deg C, 14 h photoperiod, and 600 mol m{sup -2} s{sup -1} photosynthetic photon flux (PPF), using a factorial combination of CO{sub 2} concentration (400 mol mol{sup -1} or 700 mol mol{sup -1}) and vapour pressure deficit (0.48 kPa or 1.74 kPa, which corresponded to relative humidities of 85% and 45% at 25 deg C, respectively). Elevated CO{sub 2} strongly stimulated plant growth under high VPD conditions, but this beneficial effect was not observed under low VPD. Under low VPD, elevated CO{sub 2} also did not enhance plant photosynthesis, and plant water stress was greatest for plants grown at elevated CO{sub 2} and low VPD. Moreover, plants grown under elevated CO{sub 2} and low VPD had a lower leaf soluble protein and photosynthetic activity (photosynthetic rate and carboxylation efficiency) than plants grown under elevated CO{sub 2} and high VPD. Elevated CO{sub 2} significantly increased leaf adaxial and abaxial temperatures. Because the effects of elevated CO{sub 2} were dependent on vapour pressure deficit, VPD needs to be controlled in experiments studying the effect of elevated CO{sub 2} as well as considered in the extrapolations of results to a warmer, high-CO{sub 2} world. (au)

  14. Vapour pressures and osmotic coefficients of binary mixtures of 1-ethyl-3-methylimidazolium ethylsulfate and 1-ethyl-3-methylpyridinium ethylsulfate with alcohols at T = 323.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Calvar, Noelia [Laboratory of Separation and Reaction Engineering, Departamento de Engenharia Quimica, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Gonzalez, Begona; Dominguez, Angeles [Departamento de Ingenieria Quimica, Universidad de Vigo, 36200 Vigo (Spain); Macedo, Eugenia A. [Laboratory of Separation and Reaction Engineering, Departamento de Engenharia Quimica, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)], E-mail:


    Osmotic coefficients of binary mixtures containing alcohols (ethanol, 1-propanol, and 2-propanol) and the ionic liquids 1-ethyl-3-methylimidazolium ethylsulfate and 1-ethyl-3-methylpyridinium ethylsulfate were determined at T = 323.15 K. Vapour pressure and activity coefficients of the studied systems were calculated from experimental data. The extended Pitzer model modified by Archer, and the modified NRTL model (MNRTL) were used to correlate the experimental data, obtaining standard deviations lower than 0.012 and 0.031, respectively. The mean molal activity coefficients and the excess Gibbs free energy of the studied binary mixtures were calculated from the parameters obtained with the extended Pitzer model of Archer.

  15. Technical Note: How accurate can stalagmite formation temperatures be determined using vapour bubble radius measurements in fluid inclusions?

    Directory of Open Access Journals (Sweden)

    F. Spadin


    Full Text Available Stalagmites are natural archives containing detailed information on continental climate variability of the past. Microthermometric measurements of fluid inclusion homogenisation temperatures allow determination of stalagmite formation temperatures by measuring the radius of stable laser-induced vapour bubbles inside the inclusions. A reliable method for precisely measuring the radius of vapour bubbles is presented. The method is applied to stalagmite samples for which the formation temperature is known. An assessment of the bubble radius measurement accuracy and how this error influences the uncertainty in determining the formation temperature is provided. We demonstrate that the nominal homogenisation temperature of a single inclusion can be determined with an accuracy of ±0.25 °C, if the volume of the inclusion is larger than 105 μm3. With this method, we could measure in a proof-of-principle investigation that the formation temperature of 10–20 yr old inclusions in a stalagmite taken from the Milandre cave is 9.87 ± 0.80 °C, while the mean annual surface temperature, that in the case of the Milandre cave correlates well with the cave temperature, was 9.6 ± 0.15 °C, calculated from actual measurements at that time, showing a very good agreement. Formation temperatures of inclusions formed during the last 450 yr are found in a temperature range between 8.4 and 9.6 °C, which corresponds to the calculated average surface temperature. Paleotemperatures can thus be determined within ±1.0 °C.

  16. Pressure Measurement Based on Thermocouples (United States)

    Thomsen, K.


    Measuring gas pressures reliably in a harsh radiation environment was confirmed to be tricky during operation of the liquid spallation target of MEGAPIE at the Paul Scherrer Institute (PSI). Severe drift of calibration and the loss of a sensor were experienced. At the same time, the only instrumentation that worked flawlessly in the system were thermocouples. Motivated by this experience, a novel pressure sensor for application in high radiation fields has been developed, which is based on temperature measurement. The new sensor takes advantage of the fact that the thermal conductivity over a mechanical joint exhibits a strong dependence on the contact pressure. In the novel sensor heating is applied at one point and temperatures are measured at different specific locations of the pressure gage; in particular, the temperatures on the two sides of a mechanical contact are monitored. From the observed temperature distribution the gas pressure can be derived. By choosing specific mechanical details in the lay-out, it is possible to tailor the useful measurement range. In addition to yielding pressure values, the new sensor concept admits for obtaining a measure for the accuracy of the result. This is done by continuous self monitoring of the device. The health status and based thereupon the plausibility of the indicated pressure value can be deducted by comparing sensed temperatures to expectation values for any given heating power. Malfunctioning of the pressure gage is reliably detected from the diverse readings of only one device; this can be seen as providing internal redundancy while at the same time immunity to common mode failure. After some analytical and finite element studies to verify the concept in principle, a first prototype of such a novel pressure sensor has been built at PSI. Initial measurement campaigns demonstrated the correct operation of the device as anticipated. Further potential for optimization, like designing a gage for high temperature

  17. Terminal drought-tolerant pearl millet [Pennisetum glaucum (L.) R. Br.] have high leaf ABA and limit transpiration at high vapour pressure deficit. (United States)

    Kholová, Jana; Hash, C T; Kumar, P Lava; Yadav, Rattan S; Kocová, Marie; Vadez, Vincent


    It was previously shown that pearl millet genotypes carrying a terminal drought tolerance quantitative trait locus (QTL) had a lower transpiration rate (Tr; g cm(-2) d(-1)) under well-watered conditions than sensitive lines. Here experiments were carried out to test whether this relates to leaf abscisic acid (ABA) and Tr concentration at high vapour pressure deficit (VPD), and whether that leads to transpiration efficiency (TE) differences. These traits were measured in tolerant/sensitive pearl millet genotypes, including near-isogenic lines introgressed with a terminal drought tolerance QTL (NIL-QTLs). Most genotypic differences were found under well-watered conditions. ABA levels under well-watered conditions were higher in tolerant genotypes, including NIL-QTLs, than in sensitive genotypes, and ABA did not increase under water stress. Well-watered Tr was lower in tolerant than in sensitive genotypes at all VPD levels. Except for one line, Tr slowed down in tolerant lines above a breakpoint at 1.40-1.90 kPa, with the slope decreasing >50%, whereas sensitive lines showed no change in that Tr response across the whole VPD range. It is concluded that two water-saving (avoidance) mechanisms may operate under well-watered conditions in tolerant pearl millet: (i) a low Tr even at low VPD conditions, which may relate to leaf ABA; and (ii) a sensitivity to higher VPD that further restricts Tr, which suggests the involvement of hydraulic signals. Both traits, which did not lead to TE differences, could contribute to absolute water saving seen in part due to dry weight increase differences. This water saved would become critical for grain filling and deserves consideration in the breeding of terminal drought-tolerant lines.

  18. Analysis of global water vapour trends from satellite measurements in the visible spectral range

    Directory of Open Access Journals (Sweden)

    S. Mieruch


    Full Text Available Global water vapour total column amounts have been retrieved from spectral data provided by the Global Ozone Monitoring Experiment (GOME flying on ERS-2, which was launched in April 1995, and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY onboard ENVISAT launched in March 2002. For this purpose the Air Mass Corrected Differential Optical Absorption Spectroscopy (AMC-DOAS approach has been used. The combination of the data from both instruments provides us with a long-term global data set spanning more than 11 years with the potential of extension up to 2020 by GOME-2 data on MetOp.

    Using linear and non-linear methods from time series analysis and standard statistics the trends of H2O columns and their errors have been calculated. In this study, factors affecting the trend such as the length of the time series, the magnitude of the variability of the noise, and the autocorrelation of the noise are investigated. Special emphasis has been placed on the calculation of the statistical significance of the observed trends, which reveal significant local changes from −5% per year to +5% per year. These significant trends are distributed over the whole globe. Increasing trends have been calculated for Greenland, East Europe, Siberia and Oceania, whereas decreasing trends have been observed for the northwest USA, Central America, Amazonia, Central Africa and the Arabian Peninsular.

  19. Accuracy assessment of water vapour measurements from in situ and remote sensing techniques during the DEMEVAP 2011 campaign at OHP

    Directory of Open Access Journals (Sweden)

    O. Bock


    Full Text Available The Development of Methodologies for Water Vapour Measurement (DEMEVAP project aims at assessing and improving humidity sounding techniques and establishing a reference system based on the combination of Raman lidars, ground-based sensors and GPS. Such a system may be used for climate monitoring, radiosonde bias detection and correction, satellite measurement calibration/validation, and mm-level geodetic positioning with Global Navigation Satellite Systems. A field experiment was conducted in September–October 2011 at Observatoire de Haute-Provence (OHP. Two Raman lidars (IGN mobile lidar and OHP NDACC lidar, a stellar spectrometer (SOPHIE, a differential absorption spectrometer (SAOZ, a sun photometer (AERONET, 5 GPS receivers and 4 types of radiosondes (Vaisala RS92, MODEM M2K2-DC and M10, and Meteolabor Snow White participated in the campaign. A total of 26 balloons with multiple radiosondes were flown during 16 clear nights. This paper presents preliminary findings from the analysis of all these data sets. Several classical Raman lidar calibration methods are evaluated which use either Vaisala RS92 measurements, point capacitive humidity measurements, or GPS integrated water vapour (IWV measurements. A novel method proposed by Bosser et al. (2010 is also tested. It consists in calibrating the lidar measurements during the GPS data processing. The methods achieve a repeatability of 4–5%. Changes in the calibration factor of IGN Raman lidar are evidenced which are attributed to frequent optical re-alignments. When modelling and correcting the changes as a linear function of time, the precision of the calibration factors improves to 2–3%. However, the variations in the calibration factor, and hence the absolute accuracy, between methods and types of reference data remain at the level of 7%. The intercomparison of radiosonde measurements shows good agreement between RS92 and Snow White measurements up to 12 km. An overall dry bias is found

  20. Blood Pressure Self-Measurement. (United States)

    Wagner, Stefan


    Blood pressure self-measurement has been used extensively as part of several clinical processes including in the home monitoring setting for mitigating white coat effect and gaining more detailed insights into the blood pressure variability of patients over time. Self-measurement of BP is also being used as part of telemonitoring and telemedicine processes, as well as in the waiting rooms and self-measurement rooms of general practice clinics, specialized hospital department's outpatient clinics, and in other types of care facilitates and institutions.The aim of this review is to provide an overview of where, when, and how blood pressure self-measurement is being used, which official clinical guidelines and procedures are available for its implementation, as well as the opportunities and challenges that are related to its use.

  1. When do Acacia mellifera trees use water? Responses of sap velocity to soil water availability, vapour pressure deficit and global radiation. (United States)

    de Blécourt, Marleen; Thomsen, Simon; Gröngröft, Alexander; Eschenbach, Annette


    Acacia mellifera (multi-stem deciduous tree) is one of the dominant woody species responsible for bush encroachment in southern African savannahs. However, very little is known on water use, transpiration or xylem sap flow of A. mellifera. We analyzed the responses of sap velocity in A. mellifera to soil moisture, vapour pressure deficit and global radiation. This knowledge is necessary to improve hydrological modelling and will as such contribute to our understanding of the impacts of bush encroachment in (semi) arid savannahs on the soil water balance. We monitored sap velocities at two sites that differed in tree density in a semi-arid thornbush savannah in central Namibia (mean annual precipitation = 346 mm). Sap velocities were derived using the Heat Ratio Method. Measurements were done in four periods of 3-4 months between November 2014 and September 2016. The measurement periods covered the transitions between the dry and rainy season and vice versa, and the dry season. In two of these periods we did measurements at all stems of three trees per site (a total of 17-19 stems), while in the other two periods sap velocities were measured on one stem per tree for six to eight trees per site. The study was done in the framework of SASSCAL (Southern African Science Service Centre for Climate Change and Adaptive Land Management) granted by the German Federal Ministry of Education and Research (BMBF). Preliminary results indicate that the day-to-day fluctuations in cumulative daily sap velocity showed a three-phase interaction with soil water tension (minimum soil water tension of four sensors to 1-m depth). Phase I: At soil water tension water tension had little influence on sap velocities, and fluctuations in sapflow seemed to be related to VPD and global radiation. Phase II: At soil water tensions between pF 2.5 and pF 3.2, sap velocities were negatively related to soil water tension. Phase III: At soil water tensions > pF 3.2 no sap flow could be detected.

  2. Fuel reactivity and release of pollutants and alkali vapours in pressurized combustion for combined cycle power generation

    Energy Technology Data Exchange (ETDEWEB)

    Aho, M.; Haemaelaeinen, J.; Paakkinen, K.; Rantanen, J. [VTT Energy, Jyvaeskylae (Finland); Hernberg, R.; Haeyrinen, V.; Joutsenoja, T. [Tampere Univ. of Technology (Finland). Lab. of Plasma Technology


    This project forms a part of the overall Pressurized Power Coal Combustion Project Area (PPFC) which aims at an assessment of the viability and technical merits of pressurized pulverized coal combustion, in an atmosphere of recycled flue gas and oxygen in a coordinated and harmonized programme. The objective of the research at Technical Research Centre of Finland (VTT) and Tampere University of Technology (TUT) is aimed at determining the consequences of solid fuel burning in a mixture of oxygen and recycled flue gases. Combustion conditions of a pressurized entrained flow of pulverized coal and char particles in PEFR are determined with high precision. The effects of experimental parameters on the formation of nitrogen oxides (N{sub 2}O, NO and NO{sub 2}) and gaseous alkali compounds (indicated as NaX(g) and KX(g)) are studied. An effective on-line analysis method for vaporised Na and K compounds was developed. The dependency between particle temperatures and the vaporisation of Na and K was measured with three coals. The results show that alkali removal before gas turbines is always necessary with these coals if combusted in combined cycles. Pressure decreases the formation of NO and has usually no clear effect on the formation of N{sub 2}O. The order of NO/N{sub 2}O ratios correspond to fuel-O/fuel-N ratios. Increase of PO{sub 2} (oxygen concentration) of combustion gas increases the formation of NO{sub 2}. Remarkable concentrations of NO{sub 2} were often measured at high PO{sub 2} at 800-850 deg C. Therefore, NO{sub 2} should be measured from pressurized fluidized bed reactors. Some trends of the formation of NO{sub 2} with coal differ clearly from those with its parent char: N{sub 2}O formation is not strongly temperature dependent with char, and the concentrations of N{sub 2}O formed from char are much lower than those of coal. PO{sub 2} does not effect on the formation of NO from char in the studied range

  3. High-Resolution Vertical Profile Measurements for Carbon Dioxide and Water Vapour Concentrations Within and Above Crop Canopies (United States)

    Ney, Patrizia; Graf, Alexander


    We present a portable elevator-based facility for measuring CO2 , water vapour, temperature and wind-speed profiles between the soil surface and the atmospheric surface layer above crop canopies. The end of a tube connected to a closed-path gas analyzer is continuously moved up and down over the profile range (in our case, approximately 2 m) while concentrations are logged at a frequency of 20 s^{-1} . Using campaign measurements in winter wheat, winter barley and a catch crop mixture (spring 2015 to autumn 2016) during different stages of crop development and different times of the day, we demonstrate a simple approach to correct for time lags, and the resulting profiles of 30-min mean mole fractions of CO2 and H2O over height increments of 0.025 m. The profiles clearly show the effects of soil respiration and photosynthetic carbon assimilation, varying both during the diurnal cycle and during the growing season. Profiles of temperature and wind speed are based on a ventilated finewire thermocouple and a hot-wire anemometer, respectively. Measurements over bare soil and a short plant canopy were analyzed in the framework of Monin-Obukhov similarity theory to check the validity of the measurements and raw-data-processing approach. Derived fluxes of CO2 , latent and sensible heat and momentum show good agreement with eddy-covariance measurements.

  4. The Use of Bending Angle Retrieved By GPS Radio Occultation Technique For The Measurement of The Atmospheric Water Vapour Content (United States)

    Vespe, F.; Benedetto, C.; Pacione, R.

    In the last decade the use of GPS radio occultation technique (GPS RO) has been deeply and widely investigated for retrieving physical and chemical Earth atmospheric parameters. The technique proved to be particularly precise in retrieving temperature profiles with an high vertical resolution (air) in 2 unknown (hydrostatic pressure and temperature). The system cannot be solved for lower troposphere because the water vapour pressu re is not negligible. So we are forced to include some other information such as the humidity computed by the models (ECMWF or NEP) or adding another observable in the system as the zenith troposphere delays estimated by the GPS ground stations. In this work we will investigate the possibility to retrieve humidity using only the bending angles achieved by the GPS RO. In particular, the humidity profiles are extracted differentiating the true bending angle profiles, retrieved by the GPS RO, with the dry ones, obtained by fitting and extrapolating the outer layers bending angles in a dry atmosphere model (exponential or Hopfield). The bending angles will be retrieved by CHAMP and SAC-C GPS RO data. Then the humidity profiles obtained with the proposed technique will be compared and validated with those retrieved with radio-sounding balloons over two sites at different latitudes: Brindisi (Italy) and Singapore (Japan).

  5. Quality assessment of integrated water vapour measurements at the St. Petersburg site, Russia: FTIR vs. MW and GPS techniques (United States)

    Virolainen, Yana A.; Timofeyev, Yury M.; Kostsov, Vladimir S.; Ionov, Dmitry V.; Kalinnikov, Vladislav V.; Makarova, Maria V.; Poberovsky, Anatoly V.; Zaitsev, Nikita A.; Imhasin, Hamud H.; Polyakov, Alexander V.; Schneider, Matthias; Hase, Frank; Barthlott, Sabine; Blumenstock, Thomas


    The cross-comparison of different techniques for atmospheric integrated water vapour (IWV) measurements is the essential part of their quality assessment protocol. We inter-compare the synchronised data sets of IWV values measured by the Bruker 125 HR Fourier-transform infrared spectrometer (FTIR), RPG-HATPRO microwave radiometer (MW), and Novatel ProPak-V3 global navigation satellite system receiver (GPS) at the St. Petersburg site between August 2014 and October 2016. As the result of accurate spatial and temporal matching of different IWV measurements, all three techniques agree well with each other except for small IWV values. We show that GPS and MW data quality depends on the atmospheric conditions; in dry atmosphere (IWV smaller than 6 mm), these techniques are less reliable at the St. Petersburg site than the FTIR method. We evaluate the upper bound of statistical measurement errors for clear-sky conditions as 0.29 ± 0.02 mm (1.6 ± 0.3 %), 0.55 ± 0.02 mm (4.7 ± 0.4 %), and 0.76 ± 0.04 mm (6.3 ± 0.8 %) for FTIR, GPS, and MW methods, respectively. We propose the use of FTIR as a reference method under clear-sky conditions since it is reliable on all scales of IWV variability.

  6. Effects of ozone on stomatal responses to environmental parameters (blue light, red light, CO2 and vapour pressure deficit) in three Populus deltoides × Populus nigra genotypes. (United States)

    Dumont, Jennifer; Spicher, Fabien; Montpied, Pierre; Dizengremel, Pierre; Jolivet, Yves; Le Thiec, Didier


    The effect of ozone (O(3)) on stomatal regulation was studied in three Euramerican poplar genotypes (Populus deltoides × Populus nigra: Carpaccio, Cima and Robusta). The impact of O(3) on stomatal conductance responses to variations in blue light, red light, CO(2) concentration and vapour pressure deficit (VPD) was studied. Upon O(3) exposure, a sluggish response of stomatal movements was observed, characterized by slower reactions to increases in blue light intensity, CO(2) concentration and VPD, and lower amplitude of the response to variations in light intensity. That sluggish response should be taken into account in stomatal conductance models for phytotoxic ozone dose (POD(Y)) calculations. The speed of the response to variations in environmental parameters appears as a determining factor of genotype-related sensitivity. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. The first regular measurements of ozone, carbon monoxide and water vapour in the Pacific UTLS by IAGOS

    Directory of Open Access Journals (Sweden)

    Hannah Clark


    Full Text Available We present the features seen in the first 2 months (July and August 2012 of data collected over the Pacific by IAGOS (In-service Aircraft for a Global Observing System-equipped aircraft. IAGOS is the continuation and development of the well-known MOZAIC (Measurement of Ozone and Water Vapour on Airbus in-service Aircraft project where scientific instruments were carried on commercially operated A340 aircraft to make measurements of chemical species in the atmosphere. Here, we show data from an aircraft operated by China Airlines on routes from Taipei to Vancouver, which provided the first trans-Pacific measurements by an IAGOS-equipped aircraft. We describe the chemical composition of the extratropical upper troposphere/lower stratosphere (Ex-UTLS across the Pacific basin in the Northern Hemisphere. The observed concentrations of ozone span a range from 18 to 500 ppbv indicating sources in the marine boundary layer and lowermost stratosphere, respectively. Concentrations of carbon monoxide (CO greater than 400 ppbv are observed in the Ex-UTLS suggesting that plumes of pollution have been exported from the continent. These low concentrations of ozone and high concentrations of CO were rarely recorded in 8 yr of MOZAIC observations over the Atlantic.

  8. Airborne differential absorption lidar for water vapour measurements in the upper troposphere and lower stratosphere in the spectral region around 940 nm

    Energy Technology Data Exchange (ETDEWEB)

    Poberaj, G.


    Two all-solid-state laser systems were developed and studied in detail to optimise their performance for an airborne water vapour differential absorption lidar (DIAL). Their special features are high average output powers and excellent spectral properties in the 940-nm spectral region relevant for monitoring very low water vapour contents in the upper troposphere and lower stratosphere. One system is an injection-seeded pulsed Ti:sapphire ring laser with a spectral bandwidth of 105 MHz and an average power of 1.1 W. The other system is an injection-seeded optical parametric oscillator (OPO) in a ring configuration. Using KTP as nonlinear crystal, a signal output with a spectral bandwidth of 140 MHz and an average power of 1.2 W was achieved. Both systems, the Ti:sapphire ring laser and the KTP OPO, possess spectral purity values higher than 99%. The pump source for these systems is a frequency doubled diode-pumped Nd:YAG laser operating at a repetition rate of 100 Hz. The KTP OPO system has been used as a transmitter in a new airborne water vapour DIAL instrument. For the first time, measurements of two-dimensional water vapour distributions with a high vertical (500 m) and horizontal (20 km) resolution across several potential vorticity streamers were performed. Very low water vapour mixing ratios (10-50 ppmv) and strong gradients were observed in the tropopause region. The sensitivity of the DIAL instrument in the centre of a stratospheric intrusion ranges from 3% in the near field to 12% in the far field (4 km). The first comparison experiments with in situ measuring instruments show a good agreement. Considerable differences are found between DIAL measurements and data obtained from the ECMWF operational analyses and a mesoscale numerical model. (orig.)

  9. Upper tropospheric water vapour variability over tropical latitudes ...

    Indian Academy of Sciences (India)

    Upper tropospheric water vapour variability over tropical latitudes observed using radiosonde and satellite measurements. Ghouse Basha ... Keywords. Water vapour; radiosonde; satellite measurements. ... National Atmospheric Research Laboratory (NARL), Department of Space, Government of India, Gadanki, PB No. 123 ...

  10. Relative humidity effects on water vapour fluxes measured with closed-path eddy-covariance systems with short sampling lines

    DEFF Research Database (Denmark)

    Fratini, Gerardo; Ibrom, Andreas; Arriga, Nicola


    It has been formerly recognised that increasing relative humidity in the sampling line of closed-path eddy-covariance systems leads to increasing attenuation of water vapour turbulent fluctuations, resulting in strong latent heat flux losses. This occurrence has been analyzed for very long (50 m)...

  11. Reconstruction of brachial artery pressure from noninvasive finger pressure measurements

    NARCIS (Netherlands)

    Bos, W. J.; van Goudoever, J.; van Montfrans, G. A.; van den Meiracker, A. H.; Wesseling, K. H.


    Pulse wave distortions, mainly caused by reflections, and pressure gradients, caused by flow in the resistive vascular tree, may cause differences between finger and brachial artery pressures. These differences may limit the use of finger pressure measurements. We investigated whether brachial

  12. Measuring variations of δ18O and δ2H in atmospheric water vapour using two commercial laser-based spectrometers: an instrument characterisation study

    Directory of Open Access Journals (Sweden)

    S. Pfahl


    Full Text Available Variations of stable water isotopes in water vapour have become measurable at a measurement frequency of about 1 Hz in recent years using novel laser spectroscopic techniques. This enables us to perform continuous measurements for process-based investigations of the atmospheric water cycle at the time scales relevant for synoptic and mesoscale meteorology. An important prerequisite for the interpretation of data from automated field measurements lasting for several weeks or months is a detailed knowledge about instrument properties and the sources of measurement uncertainty. We present here a comprehensive characterisation and comparison study of two commercial laser spectroscopic systems based on cavity ring-down spectroscopy (Picarro and off-axis integrated cavity output spectroscopy (Los Gatos Research. The uncertainty components of the measurements were first assessed in laboratory experiments, focussing on the effects of (i water vapour mixing ratio, (ii measurement stability, (iii uncertainties due to calibration and (iv response times of the isotope measurements due to adsorption-desorption processes on the tubing and measurement cavity walls. Based on the experience from our laboratory experiments, we set up a one-week field campaign for comparing measurements of the ambient isotope signals from the two laser spectroscopic systems. The optimal calibration strategy determined for both instruments was applied as well as the correction functions for water vapour mixing ratio effects. The root mean square difference between the isotope signals from the two instruments during the field deployment was 2.3‰ for δ2H, 0.5‰ for δ18O and 3.1‰ for deuterium excess. These uncertainty estimates from field measurements compare well to those found in the laboratory experiments. The present quality of measurements from laser spectroscopic instruments combined with a calibration system opens new possibilities for investigating the atmospheric

  13. Inherent calibration of a blue LED-CE-DOAS instrument to measure iodine oxide, glyoxal, methyl glyoxal, nitrogen dioxide, water vapour and aerosol extinction in open cavity mode

    Directory of Open Access Journals (Sweden)

    R. Thalman


    Full Text Available The combination of Cavity Enhanced Absorption Spectroscopy (CEAS with broad-band light sources (e.g. Light-Emitting Diodes, LEDs lends itself to the application of cavity enhanced Differential Optical Absorption Spectroscopy (CE-DOAS to perform sensitive and selective point measurements of multiple trace gases and aerosol extinction with a single instrument. In contrast to other broad-band CEAS techniques, CE-DOAS relies only on the measurement of relative intensity changes, i.e. does not require knowledge of the light intensity in the absence of trace gases and aerosols (I0. We have built a prototype LED-CE-DOAS instrument in the blue spectral range (420–490 nm to measure nitrogen dioxide (NO2, glyoxal (CHOCHO, methyl glyoxal (CH3COCHO, iodine oxide (IO, water vapour (H2O and oxygen dimers (O4. We demonstrate the first direct detection of methyl glyoxal, and the first CE-DOAS detection of CHOCHO and IO. The instrument is further inherently calibrated for light extinction from the cavity by observing O4 or H2O (at 477 nm and 443 nm and measuring the pressure, relative humidity and temperature independently. This approach is demonstrated by experiments where laboratory aerosols of known size and refractive index were generated and their extinction measured. The measured extinctions were then compared to the theoretical extinctions calculated using Mie theory (3–7 × 10−7cm−1. Excellent agreement is found from both the O4 and H2O retrievals. This enables the first inherently calibrated CEAS measurement at blue wavelengths in open cavity mode, and eliminates the need for sampling lines to supply air to the cavity, i.e., keep the cavity enclosed and/or aerosol free. Measurements in open cavity mode are demonstrated for CHOCHO, CH3COCHO, NO2, H2O and aerosol extinction. Our prototype

  14. estimation of precipitable water vapour in nigeria using surface ...

    African Journals Online (AJOL)


    affects the climate and weather systems through its effect on the atmospheric temperature and energy transport (Garrison, 1992; Follette et al.,. 2008). A very important measure of the atmospheric water vapour is the precipitable water vapour. (PWV). Precipitable Water Vapour (PWV) is a measure of the total amount of water ...

  15. In situ measurement of CO2 and water vapour isotopic compositions at a forest site using mid-infrared laser absorption spectroscopy. (United States)

    Wada, Ryuichi; Matsumi, Yutaka; Takanashi, Satoru; Nakai, Yuichiro; Nakayama, Tomoki; Ouchi, Mai; Hiyama, Tetsuya; Fujiyoshi, Yasushi; Nakano, Takashi; Kurita, Naoyuki; Muramoto, Kenichiro; Kodama, Naomi


    We conducted continuous, high time-resolution measurements of CO2 and water vapour isotopologues ((16)O(12)C(16)O, (16)O(13)C(16)O and (18)O(12)C(16)O for CO2, and H2(18)O for water vapour) in a red pine forest at the foot of Mt. Fuji for 9 days from the end of July 2010 using in situ absorption laser spectroscopy. The δ(18)O values in water vapour were estimated using the δ(2)H-δ(18)O relationship. At a scale of several days, the temporal variations in δ(18)O-CO2 and δ(18)O-H2O are similar. The orders of the daily Keeling plots are almost identical. A possible reason for the similar behaviour of δ(18)O-CO2 and δ(18)O-H2O is considered to be that the air masses with different water vapour isotopic ratios moved into the forest, and changed the atmosphere of the forest. A significant correlation was observed between δ(18)O-CO2 and δ(13)C-CO2 values at nighttime (r(2)≈0.9) due to mixing between soil (and/or leaf) respiration and tropospheric CO2. The ratios of the discrimination coefficients (Δa/Δ) for oxygen (Δa) and carbon (Δ) isotopes during photosynthesis were estimated in the range of 0.7-1.2 from the daytime correlations between δ(18)O-CO2 and δ(13)C-CO2 values.

  16. Pressures Detector Calibration and Measurement

    CERN Document Server



    This is report of my first and second projects (of 3) in NA61. I did data taking and analysis in order to do calibration of pressure detectors and verified it. I analyzed the data by ROOT software using the C ++ programming language. The first part of my project was determination of calibration factor of pressure sensors. Based on that result, I examined the relation between pressure drop, gas flow rate of in paper filter and its diameter.

  17. Vapour pressures, aqueous solubilities, Henry's law constants, partition coefficients between gas/water (Kgw), n-octanol/water (Kow) and gas/n-octanol (Kgo) of 106 polychlorinated diphenyl ethers (PCDE) (United States)

    Kurz; Ballschmiter


    Modelling the environmental fate of persistent organic pollutants like polychlorinated diphenyl ethers (PCDE) requires the knowledge of a number of fundamental physico-chemical properties of these compounds. We report here the physico-chemical properties of 106 PCDEs, which are over 50% of all possible congeners. Vapour pressures P(OL), water solubilities S(H2O), and n-octanol/water partition coefficients K(OW) were determined with chromatographic methods. With these experimental data the Henry's law constants H, gas/water K(GW) and gas/n-octanol K(GO) partition coefficients were calculated. Vapour pressures and water solubilities and n-octanol/water partition coefficients of the PCDEs are close to those of similar groups of organochlorine compounds like polychlorinated biphenyls (PCBs) and dibenzofurans (PCDFs). A similar environmental fate can be predicted and was partially already been observed.

  18. High Precision Pressure Measurement with a Funnel (United States)

    Lopez-Arias, T.; Gratton, L. M.; Oss, S.


    A simple experimental device for high precision differential pressure measurements is presented. Its working mechanism recalls that of a hydraulic press, where pressure is supplied by insufflating air under a funnel. As an application, we measure air pressure inside a soap bubble. The soap bubble is inflated and connected to a funnel which is…

  19. New Vision Sensor to Measure Gas Pressure

    Directory of Open Access Journals (Sweden)

    Murawski Krzysztof


    Full Text Available The paper presents the construction and operation of a video sensor developed for video-manometer. In the publication the use of video-manometer for measuring gas pressure is presented. A characteristic feature of the device is pressure measurement based on diaphragm deformation and digital image processing. Presented measuring technique eliminates restrictions in the construction of the measuring apparatus arising from non-linear nature of diaphragm deformation. It also allows performing measurements of gas pressure, also of explosive gas, providing galvanic isolation between the factor measured and the measuring device. The paper presents the results of video-manometer calibration and measurements taken during the laboratory tests. It has been shown that the developed video-manometer, that is equipped with a flat silicone diaphragm, allows measuring the gas pressure in the range of 0 – 100 mbar with an error less than 2 %. In the experiments the CO2 pressure was measured.

  20. Vapour pressures, aqueous solubilities, Henry's Law constants, and octanol/water partition coefficients of a series of mixed halogenated dimethyl bipyrroles. (United States)

    Tittlemier, Sheryl A; Braekevelt, Eric; Halldorson, Thor; Reddy, Christopher M; Norstrom, Ross J


    Basic physical-chemical properties of five bromine and chlorine containing mixed halogenated dimethyl bipyrroles (HDBPs) were determined using established methods. Subcooled liquid vapour pressures (P(o)(L,25)), aqueous solubilities (S(w,25)), and octanol/water partition coefficients (K(ow)) were determined using the gas chromatography-retention time, generator column, and slow-stirring methods, respectively. Henry's Law constants (H25) were estimated using experimentally-derived P(o)(L) and S(w,25) data. Values of all four properties were generally similar to those reported for other polyhalogenated aromatic compounds [P(o)(L,25) = (7.55-191) x 10(-6) Pa; S(w,25) = (1.0-1.9) x 10(-5) g/l; log K(ow) = 6.4-6.7; H25 = 0.0020-0.14 Pa m3/mol]. The effect of replacing a chlorine with a bromine atom significantly decreased P(o)(L,25) (log P(o)(L,25) = -0.4197 (# bromine atoms) - 2.643, p<0.01) and H25 (log H25 = -0.508 (# bromine atoms) + 0.394, p<0.02). There were no significant effects of bromine/chlorine substitution on S(w,25) or K(ow). A simple Level I equilibrium partitioning model predicted the environmental behaviour of HDBPs to be similar to a tetrabrominated diphenyl ether. Only slight differences in behaviour amongst HDBP congeners were predicted since substitution of a bromine for a chlorine (Cl/Br substitution) atom had less effect than H/Cl or H/Br substitution on P(o)(L,25), S(w,25), H25, and K(ow).

  1. Effects of drought and changes in vapour pressure deficit on water relations of Populusdeltoides growing in ambient and elevated CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Bobich, E.G.; Barron-Gafford, G.A.; Rascher, K.G. [Columbia Univ., Oracle, AZ (United States). Biosphere 2 Center; Murthy, R. [Columbia Univ., Oracle, AZ (United States). Biosphere 2 Center, Earth and Environmental Sciences, Lamont-Doherty Earth Observatory


    According to the Intergovernmental Panel on Climate Change (IPCC), changes in the earth's climate are expected to become more extreme as carbon dioxide (CO{sub 2}) concentrations increase over the next century. This study examined the means by which growth CO{sub 2} concentration affects anatomy and water relation responses to drought and vapour pressure deficit (VPD). Yearly coppiced, 4-year-old Populus deltoides clones grown in either ambient or elevated CO{sub 2} for 3 years were examined to determine if trees growing in elevated CO{sub 2} during drought would have a lower volume flux density of water (JV), stomatal conductance (gs) and transpiration per leaf area (E), as well as a lower stomatal density and a greater stomatal response to drought and changes in VPD than would trees in ambient CO{sub 2}. The study showed that trees in elevated CO{sub 2} actually had higher JV values, but did not differ from trees in ambient CO{sub 2} in terms of gs or E under saturating light or E scaled from JV. The higher JV in elevated CO{sub 2} was attributed to the greater leaf area in the trees and not from differences in gs. Plants in elevated CO{sub 2} had greater absolute leaf loss during the drought, but the percentage of leaf area lost was similar to that of trees in ambient CO{sub 2}. Under saturating light, gs and E were influenced by changes in VPD after the first 9 days of the experiment, which coincided with a large decrease in water potential. It was concluded that longer-term growth of P. deltoides clone under elevated CO{sub 2} did not improve the effects of drought and high VPD on plant and water relations. 56 refs., 3 tabs., 4 figs.

  2. Blood pressure measurement on the cheek

    Directory of Open Access Journals (Sweden)

    Schneider Sarah


    Full Text Available In a large group of patients, it is impossible to measure blood pressure using an upper arm cuff. An alternative, non-invasive method of blood pressure measurement is required for patients with severe limb deformities or obesity, for amputees, and in the emergency medicine. The device proposed here measures blood pressure in the cheek using a small pressure pad and a pump to occlude the cheek artery – arteria facialis – and assesses blood flow with an infrared light source and a detector. The infrared light signal is analysed to assess the systolic and diastolic blood pressure of the patient. Manual evaluation of the light intensity signal showed a good agreement between cheek blood pressure measurement and a reference measurement using an upper arm cuff.

  3. The Liquid Vapour Interface

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage


    In this short review we are concerned with the density variation across the liquid-vapour interface, i.e. from the bulk density of the liquid to the essentially zero density of the vapour phase. This density variation can in principle be determined from the deviation of the reflectivity from...

  4. Foot Plantar Pressure Measurement System: A Review

    Directory of Open Access Journals (Sweden)

    Yufridin Wahab


    Full Text Available Foot plantar pressure is the pressure field that acts between the foot and the support surface during everyday locomotor activities. Information derived from such pressure measures is important in gait and posture research for diagnosing lower limb problems, footwear design, sport biomechanics, injury prevention and other applications. This paper reviews foot plantar sensors characteristics as reported in the literature in addition to foot plantar pressure measurement systems applied to a variety of research problems. Strengths and limitations of current systems are discussed and a wireless foot plantar pressure system is proposed suitable for measuring high pressure distributions under the foot with high accuracy and reliability. The novel system is based on highly linear pressure sensors with no hysteresis.

  5. Blood pressure measurements taken by patients are similar to home and ambulatory blood pressure measurements

    Directory of Open Access Journals (Sweden)

    Angela M. G. Pierin


    Full Text Available OBJECTIVE: To compare blood pressure measurements taken at home by physicians, nurses, and patients with office blood pressure measurement , ambulatory blood pressure monitoring and home blood pressure measurement. METHODS: A total of 44 patients seen by a home care program were studied. Protocol 1 a blood pressure was measured by the patient, a physician and a nurse during a regular home visit (Home1; b home blood pressure measurement was measured for 4 days (HBPM1; c office blood pressure measurement was measured by a physician, a nurse, and the patient; and by 24-hour ambulatory blood pressure monitoring. Protocol 2 blood pressure was measured by the patient, a physician, and a nurse during a special home visit in the presence of a physician and a nurse only (Home2; and b home blood pressure measurement was taken for the second time (HBPM2. Echocardiography, guided by a two-dimensional echocardiograph, was performed. RESULTS: Protocol 1: a office blood pressure measurement and Home1 were significantly higher than ambulatory blood pressure monitoring, except for systolic and diastolic office blood pressure measurement taken by the patient or a family member, systolic blood pressure taken by a nurse, and diastolic blood pressure taken by a physician. b ambulatory blood pressure monitoring and HBPM1 were similar. Protocol 2: a HBPM2 and Home2 were similar. b Home2 was significantly lower than Home1, except for diastolic blood pressure taken by a nurse or the patient. There were significant relationships between: a diastolic blood pressure measured by the patient and the thickness of the interventricular septum, posterior wall, and left ventricular mass; and b ambulatory and HBPM2 diastolic and systolic blood pressure taken by a physician (home2 and left ventricular mass. Therefore, the data indicate that home blood pressure measurement and ambulatory blood pressure monitoring had good prognostic values relative to "office measurement

  6. An underwater blood pressure measuring device. (United States)

    Sieber, Arne; Kuch, Benjamin; L'abbate, Antonio; Wagner, Matthias; Dario, Paolo; Bedini, Remo


    Measurement of arterial blood pressure is an important vital sign for monitoring the circulation. However, up to now no instrument has been available that enables the measurement of blood pressure underwater. The present paper details a novel, oscillometric, automatic digital blood pressure (BP) measurement device especially designed for this purpose. It consists mainly of analogue and digital electronics in a lexan housing that is rated to a depth of up to 200 metres' sea water, a cuff and a solenoid for inflation of the cuff with air supplied from a scuba tank. An integrated differential pressure sensor, exposed to the same ambient pressure as the cuff, allows accurate BP measurement. Calculation of systolic and diastolic pressures is based on the analysis of pressure oscillations recorded during the deflation. In hyperbaric chamber tests to pressures up to 405 kPa, BP measurements taken with the prototype were comparable to those obtained with established manual and automated methods. Swimming pool tests confirmed the correct functioning of the system underwater. The quality of the recorded pressure oscillations was very good even at 10 metres' fresh water, and allowed determination of diastolic and systolic pressure values. Based on these results we envisage that this device will lead to a better understanding of human cardiovascular physiology in underwater and hyperbaric environments.

  7. Oscillometric blood pressure measurements: differences between measured and calculated mean arterial pressure.

    NARCIS (Netherlands)

    Kiers, H.D.; Hofstra, J.M.; Wetzels, J.F.M.


    Mean arterial pressure (MAP) is often used as an index of overall blood pressure. In recent years, the use of automated oscillometric blood pressure measurement devices is increasing. These devices directly measure and display MAP; however, MAP is often calculated from systolic blood pressure (SBP)

  8. Optical Measurement Of Sound Pressure (United States)

    Trinh, Eugene H.; Gaspar, Mark; Leung, Emily W.


    Noninvasive technique does not disturb field it measures. Sound field deflects laser beam proportionally to its amplitude. Knife edge intercepts undeflected beam, allowing only deflected beam to reach photodetector. Apparatus calibrated by comparing output of photodetector with that of microphone. Optical technique valuable where necessary to measure in remote, inaccessible, or hostile environment or to avoid perturbation of measured region.

  9. Pirani pressure sensor with distributed temperature measurement

    NARCIS (Netherlands)

    de Jong, B.R.; Bula, W.P.; Zalewski, D.R.; van Baar, J.J.J.; Wiegerink, Remco J.


    Surface micro-machined distributed Pirani pressure gauges, with designed heater-to-heat sink distances (gap-heights) of 0.35 μm and 1.10 μm, are successfully fabricated, modeled and characterized. Measurements and model response correspond within 5% of the measured value in a pressure range of 10 to

  10. Rotatory power of sodium vapour oriented by laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bicchi, P. (Siena Univ. (Italy). Ist. di Fisica); Moi, L.; Zambon, B. (Consiglio Nazionale delle Ricerche, Pisa (Italy). Lab. di Fisica Atomica e Moleculare)


    In this paper the rotatory power of sodium vapour is studied when laser light is used as pumping as well as analysis light. The possibility of having an analysis light whose frequency may be varied in a range larger than the interval between the D/sub 1/ and D/sub 2/ atomic lines allows us to get for the first time the complete shape of the rotation curve and to measure a rotation different from zero even for frequencies very far from the resonance ones. The complete orientation in the vapour caused by the laser pumping-light power permits to obtain very high rotation values. In a cell containing Na and 200 Torr of Ne, we measured, at 185/sup 0/C, 10/sup 0//cm of specific rotation. The dependence of the optical activity on the buffer gas pressure and on the frequency of the pumping light is also studied.

  11. Micro packaged MEMS pressure sensor for intracranial pressure measurement (United States)

    Xiong, Liu; Yan, Yao; Jiahao, Ma; Yanhang, Zhang; Qian, Wang; Zhaohua, Zhang; Tianling, Ren


    This paper presents a micro packaged MEMS pressure sensor for intracranial pressure measurement which belongs to BioMEMS. It can be used in lumbar puncture surgery to measure intracranial pressure. Miniaturization is key for lumbar puncture surgery because the sensor must be small enough to allow it be placed in the reagent chamber of the lumbar puncture needle. The size of the sensor is decided by the size of the sensor chip and package. Our sensor chip is based on silicon piezoresistive effect and the size is 400 × 400 μm2. It is much smaller than the reported polymer intracranial pressure sensors such as liquid crystal polymer sensors. In terms of package, the traditional dual in-line package obviously could not match the size need, the minimal size of recently reported MEMS-based intracranial pressure sensors after packaging is 10 × 10 mm2. In this work, we are the first to introduce a quad flat no-lead package as the package form of piezoresistive intracranial pressure sensors, the whole size of the sensor is minimized to only 3 × 3 mm2. Considering the liquid measurement environment, the sensor is gummed and waterproof performance is tested; the sensitivity of the sensor is 0.9 × 10-2 mV/kPa. Project supported by the National Natural Science Foundation of China (Nos. 61025021, 61434001), and the ‘Thousands Talents’ Program for Pioneer Researchers and Its Innovation Team, China.

  12. Convective heat transfer measurements in a vapour-liquid-liquid three-phase direct contact heat exchanger (United States)

    Mahood, Hameed B.; Campbell, A. N.; Baqir, Ali Sh.; Sharif, A. O.; Thorpe, R. B.


    Energy usage is increasing around the world due to the continued development of technology, and population growth. Solar energy is a promising low-grade energy resource that can be harvested and utilised in different applications, such solar heater systems, which are used in both domestic and industrial settings. However, the implementation of an efficient energy conversion system or heat exchanger would enhance such low-grade energy processes. The direct contact heat exchanger could be the right choice due to its ability to efficiently transfer significant amounts of heat, simple design, and low cost. In this work, the heat transfer associated with the direct contact condensation of pentane vapour bubbles in a three-phase direct contact condenser is investigated experimentally. Such a condenser could be used in a cycle with a solar water heater and heat recovery systems. The experiments on the steady state operation of the three-phase direct contact condenser were carried out using a short Perspex tube of 70 cm in total height and an internal diameter of 4 cm. Only a height of 48 cm was active as the direct contact condenser. Pentane vapour, (the dispersed phase) with three different initial temperatures (40° C, 43.5° C and 47.5° C) was directly contacted with water (the continuous phase) at 19° C. The experimental results showed that the total heat transfer rate per unit volume along the direct contact condenser gradually decreased upon moving higher up the condenser. Additionally, the heat transfer rate increases with increasing mass flow rate ratio, but no significant effect on the heat transfer rate of varying the initial temperature of the dispersed phase was seen. Furthermore, both the outlet temperature of the continuous phase and the void fraction were positively correlated with the total heat transfer rate per unit volume, with no considerable effect of the initial temperature difference between the dispersed and continuous phases.

  13. Effects of drought and changes in vapour pressure deficit on water relations of Populus deltoides growing in ambient and elevated CO2. (United States)

    Bobich, Edward G; Barron-Gafford, Greg A; Rascher, Katherine G; Murthy, Ramesh


    The means by which growth CO(2) concentration ([CO(2)]) affects anatomy and water relations responses to drought and vapour pressure deficit (VPD) were studied for yearly coppiced, 4-year-old Populus deltoides clones that were grown in either 400 mumol mol(-1) (ambient) or 800 mumol mol(-1) (elevated) CO(2) for 3 years. It was hypothesized that, during drought, trees growing in elevated [CO(2)] would have a lower volume flux density of water (J(V)), stomatal conductance (g(s)) and transpiration per leaf area (E), as well as a lower stomatal density and a greater stomatal response to drought and changes in VPD than would trees in ambient [CO(2)]. Trees in elevated [CO(2)] actually had higher J(V) values throughout the study, but did not differ from trees in ambient [CO(2)] with respect to g(s) or E under saturating light or E scaled from J(V) (E(scaled)), all of which indicates that the higher J(V) in elevated [CO(2)] resulted from those trees having greater leaf area and not from differences in g(s). Furthermore, although plants in elevated [CO(2)] had greater absolute leaf loss during the drought, the percentage of leaf area lost was similar to that of trees in ambient [CO(2)]. g(s) and E under saturating light were affected by changes in VPD after the first 9 days of the experiment, which coincided with a large decrease in water potential at a soil depth of 0.1 m. Trees in elevated [CO(2)] had a greater stomatal density and a lower wood density than trees in ambient [CO(2)], both traits that may make the trees more susceptible to xylem cavitation in severe drought. Drought and VPD effects for the P. deltoides clone were not ameliorated by long-term growth in elevated [CO(2)] compared with ambient [CO(2)], and plants in elevated [CO(2)] possessed anatomical traits that may result in greater stress associated with long-term drought.

  14. Borehole pressure and temperature measurement system

    Energy Technology Data Exchange (ETDEWEB)

    Perales, K.L.


    This patent describes apparatus for continuously measuring fluctuating pressure and temperature of a downhole fluid in a borehole at a desired depth. It comprises a tube positioned within the borehole; a housing suspended in the borehole at the desired depth from the tube; a pressurized test fluid source at the surface for initially pressuring the flow path in the tube and a portion of the chamber in the housing; a valve for selectively isolating fluid communications between the tube and the pressurized test fluid source; a thermocouple line including two dissimilar metal conductors; a manifold at the surface for sealing the selected fluid within the flow path; a pressure measuring device at the surface and in fluid communication; and a temperature measuring device at the surface for receiving the thermocouple line.

  15. Measurement and Applications of Radiation Pressure (United States)

    Ma, Dakang; Garrett, Joseph; Murray, Joseph; Munday, Jeremy; Munday Lab Team

    Light reflected off a material or absorbed within it exerts radiation pressure through the transfer of momentum. Measuring and utilizing radiation pressure have aroused growing interest in a wide spectrum of research fields. Micromechanical transducers and oscillators are good candidates for measuring radiation pressure, but accompanying photothermal effects often obscure the measurement. In this work, we investigate the accurate measurement of the radiation force on microcantilevers in ambient conditions and ways to separate radiation pressure and photothermal effects. Further, we investigate an optically broadband switchable device based on polymer dispersed liquid crystal which has potential applications in solar sails and maneuvering spacecraft without moving parts. The authors would like to thank NASA Early Career Faculty Award and NASA Smallsat Technology Partnership Award for their funding support.

  16. Attempted eyelid closure affects intraocular pressure measurement. (United States)

    Gandhi, P D; Gürses-Ozden, R; Liebmann, J M; Ritch, R


    To evaluate the effect of attempted eyelid closure on intraocular pressure measurement. Normal subjects underwent intraocular pressure measurement in both eyes using Goldmann applanation tonometry and Tono-pen XL (Mentor, Inc, Norwell, Massachusetts) by the same examiner holding the eyelids open, both with and without the subject simultaneously attempting forced eyelid closure. Subjects were seated during all measurements and waited 5 minutes between measurements with each instrument; the order of measurement was randomized. Thirty eyes of 15 subjects (six men, nine women) were enrolled. Mean age was 30.5 +/- 5.2 years (range, 24 to 40 years). With Goldmann applanation tonometry, intraocular pressure increased in both eyes with attempted eyelid closure by a mean of 1.5 +/- 2.0 mm Hg (P =.0002, paired t test; range, -2 to 8 mm Hg). With the Tono-pen XL, intraocular pressure also increased in both eyes with attempted eyelid closure by a mean of 1.9 +/- 2.7 mm Hg (P =.0002, paired t test; range, -2 to 9 mm Hg). Tono-pen XL mean intraocular pressure values in both eyes (14.4 +/- 2.3 mm Hg) consistently overestimated those of Goldmann applanation tonometry (13.0 +/- 2.2 mm Hg) by a mean of 1.4 +/- 2.3 mm Hg. Attempted forced eyelid closure is a common and statistically significant source of error in routine outpatient measurement of intraocular pressure and could influence clinical management of glaucoma.

  17. Measuring Pressure Drop Under Non Ideal Conditions

    Directory of Open Access Journals (Sweden)

    Austin M


    Full Text Available The method of measurement of the pressure drop (PD of cigarette filter rods and the draw resistance of cigarettes is defined in ISO 6565-2002 (1. This standard defines the calibration and use of a transfer standard to calibrate the measuring instrument and also defines the measurement procedure for cigarette and filter samples. The procedure described in the standard assumes that the measurement conditions are constant and that the sample is in equilibrium with the measurement environment.

  18. Pancreas tumor interstitial pressure catheter measurement (United States)

    Nieskoski, Michael D.; Gunn, Jason; Marra, Kayla; Trembly, B. Stuart; Pogue, Brian W.


    This paper highlights the methodology in measuring interstitial pressure in pancreatic adenocarcinoma tumors. A Millar Mikrotip pressure catheter (SPR-671) was used in this study and a system was built to amplify and filter the output signal for data collection. The Millar pressure catheter was calibrated prior to each experiment in a water column at 37°C, range of 0 to 60 inH2O (112 mmHg), resulting in a calibration factor of 33 mV / 1 inH2O. The interstitial pressures measured in two orthotopically grown pancreatic adenocarcinoma tumor were 57 mmHg and 48 mmHg, respectively. Verteporfin uptake into the pancreatic adenocarcinoma tumor was measured using a probe-based experimental dosimeter.

  19. On output measurements via radiation pressure

    DEFF Research Database (Denmark)

    Leeman, S.; Healey, A.J.; Forsberg, F.


    It is shown, by simple physical argument, that measurements of intensity with a radiation pressure balance should not agree with those based on calorimetric techniques. The conclusion is ultimately a consequence of the circumstance that radiation pressure measurements relate to wave momentum, while...... calorimetric methods relate to wave energy. Measurements with some typical ultrasound fields are performed with a novel type of hydrophone, and these allow an estimate to be made of the magnitude of the discrepancy to be expected between the two types of output measurement in a typical case....

  20. The 1997 El Niño impact on clouds, water vapour, aerosols and reactive trace gases in the troposphere, as measured by the Global Ozone Monitoring Experiment

    Directory of Open Access Journals (Sweden)

    D. Loyola


    Full Text Available The El Niño event of 1997/1998 caused dry conditions over the Indonesian area that were followed by large scale forest and savannah fires over Kalimantan, Sumatra, Java, and parts of Irian Jaya. Biomass burning was most intense between August and October 1997, and large amounts of ozone precursors, such as nitrogen oxides, carbon monoxide and hydrocarbons were emitted into the atmosphere. In this work, we use satellite measurements from the Global Ozone Monitoring Experiment (GOME sensor to study the teleconnections between the El Niño event of 1997 and the Indonesian fires, clouds, water vapour, aerosols and reactive trace gases (nitrogen dioxide, formaldehyde and ozone in the troposphere.

  1. [Contemporary possibilities of intraocular pressure measurement]. (United States)

    Hornová, J; Baxant, A


    Authors introduced current possibilities of measuring intraocular pressure (IOP). A list of available methods of monitoring IOP is published; contact measurement method IOP directly on the cornea, but also over upper lid, methodology of minimal contact and non-contact measurement. Following contact methods are described; former measurements of IOP by impression Schiotz tonometer and the current methodology applanation. So far as the gold standard measurement Goldmann applanation tonometer (GAT) is considered, another methodology with applanation measurements are compared: Pascal dynamic contoured tonometer (DCT ), BioResonator - resonant applanation tonometer (ART ), digital applanation tonometer Tonopen and last hit: continuous measurement of IOP by Sensimed Triggerfish. Orientation and rapid assessment is palpation pressure control over the lid and measuring by tonometer Diaton. Rebound tonometer (RBT) iCare belongs to measurements with minimal contact, no need anesthetic drops and fluorescein, therefore a self - home version of IOP measurements (Icare ONE) is developed. Non-contact measurement of IOP by different pneumotonometers is popular for screening assessment of IOP. Reichert Ocular Response Analyzer (ORA) is a non-contact applanation IOP measurement and reveals additional properties of the cornea. In the discussion of a range methodology is evaluated, the experience of other authors and their own experience is compared. For monitoring of patients is necessary to select the most suitable methodology, measure repeatedly and accurately to allow long-term monitoring of intraocular pressure.

  2. Validation of water vapour profiles (version 13 retrieved by the IMK/IAA scientific retrieval processor based on full resolution spectra measured by MIPAS on board Envisat

    Directory of Open Access Journals (Sweden)

    M. Milz


    Full Text Available Vertical profiles of stratospheric water vapour measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS with the full resolution mode between September 2002 and March 2004 and retrieved with the IMK/IAA scientific retrieval processor were compared to a number of independent measurements in order to estimate the bias and to validate the existing precision estimates of the MIPAS data. The estimated precision for MIPAS is 5 to 10% in the stratosphere, depending on altitude, latitude, and season. The independent instruments were: the Halogen Occultation Experiment (HALOE, the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS, the Improved Limb Atmospheric Spectrometer-II (ILAS-II, the Polar Ozone and Aerosol Measurement (POAM III instrument, the Middle Atmospheric Water Vapour Radiometer (MIAWARA, the Michelson Interferometer for Passive Atmospheric Sounding, balloon-borne version (MIPAS-B, the Airborne Microwave Stratospheric Observing System (AMSOS, the Fluorescent Stratospheric Hygrometer for Balloon (FLASH-B, the NOAA frostpoint hygrometer, and the Fast In Situ Hygrometer (FISH. For the in-situ measurements and the ground based, air- and balloon borne remote sensing instruments, the measurements are restricted to central and northern Europe. The comparisons to satellite-borne instruments are predominantly at mid- to high latitudes on both hemispheres. In the stratosphere there is no clear indication of a bias in MIPAS data, because the independent measurements in some cases are drier and in some cases are moister than the MIPAS measurements. Compared to the infrared measurements of MIPAS, measurements in the ultraviolet and visible have a tendency to be high, whereas microwave measurements have a tendency to be low. The results of χ2-based precision validation are somewhat controversial among the comparison estimates. However, for comparison instruments whose error budget also includes

  3. Determination and modelling of osmotic coefficients and vapour pressures of binary systems 1- and 2-propanol with C{sub n}MimNTf{sub 2} ionic liquids (n = 2, 3, and 4) at T = 323.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Calvar, Noelia [LSRE - Laboratory of Separation and Reaction Engineering, Associate Laboratory, LSRE/LCM, Department of Chemical Engineering, Faculty of Engineering, Rua Dr. Roberto Frias s/n, Porto 4200-465 (Portugal); Gomez, Elena; Dominguez, Angeles [Advanced Separation Processes Group, Department of Chemical Engineering, University of Vigo, 36310 Vigo (Spain); Macedo, Eugenia A., E-mail: [LSRE - Laboratory of Separation and Reaction Engineering, Associate Laboratory, LSRE/LCM, Department of Chemical Engineering, Faculty of Engineering, Rua Dr. Roberto Frias s/n, Porto 4200-465 (Portugal)


    Highlights: > Osmotic coefficients of 1- and 2-propanol with C{sub n}MimNTf{sub 2} (n = 2, 3, and 4) are determined. > Experimental data were correlated with extended Pitzer model of Archer and MNRTL. > Mean molal activity coefficients and excess Gibbs free energies were calculated. > Effect of the anion is studied comparing these results with literature. - Abstract: The osmotic and activity coefficients and vapour pressures of binary mixtures containing 1-propanol, or 2-propanol and imidazolium-based ionic liquids with bis(trifluoromethylsulfonyl)imide as anion (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, C{sub 2}MimNTf{sub 2}, 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide, C{sub 3}MimNTf{sub 2}, and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, C{sub 4}MimNTf{sub 2}) were determined at T = 323.15 K using the vapour pressure osmometry technique. The experimental osmotic coefficients were correlated using the extended Pitzer model modified by Archer and the MNRTL model, obtaining standard deviations lower than 0.033 and 0.064, respectively. The mean molal activity coefficients and the excess Gibbs free energy for the mixtures studied were calculated from the parameters of the extended Pitzer model modified by Archer. Besides the effect of the alkyl-chain of the cation, the effect of the anion can be assessed comparing the experimental results with those previously obtained for imidazolium ionic liquids with sulphate anions.

  4. Working meeting on blood pressure measurement: suggestions for measuring blood pressure to use in populations surveys. (United States)


    As part of the Pan American Hypertension Initiative (PAHI), the Pan American Health Organization and the National Heart, Lung, and Blood Institute of the National Institutes of Health of the United States of America conducted a working meeting to discuss blood pressure (BP) measurement methods used in various hypertension prevalence surveys and clinical trials, with the objective of developing a BP measurement protocol for use in hypertension prevalence surveys in the Americas. No such common protocol has existed in the Americas, so it has been difficult to compare hypertension prevention and intervention strategies. This piece describes a proposed standard method for measuring blood pressure for use in population surveys in the Region of the Americas. The piece covers: considerations for developing a common blood pressure measurement protocol, critical issues in measuring blood pressure in national surveys, minimum procedures for blood pressure measurement during surveillance, and quality assessment of blood pressure.

  5. Validation of HITEMP-2010 for carbon dioxide and water vapour at high temperatures and atmospheric pressures in 450-7600cm-1 spectral range

    DEFF Research Database (Denmark)

    Alberti, Michael; Weber, Roman; Mancini, Marco


    The objective of the work is validation of HITEMP-2010 at atmospheric pressures and temperatures reaching 1770K. To this end, spectral transmissivities at 1cm-1 resolution and excellent signal-to-noise-ratio have been measured for 22 CO2/H2O/N2 mixtures. In this paper we consider the 450cm-1-7600...... absorption lines listed in HITEMP-2010 have not been observed in the measured spectra and/or are wrongly scaled with temperature. The complete (there are no missing bands) spectra spanning the 450-7600cm-1 range are appended as Supplementary Material....

  6. Patient-Specific Oscillometric Blood Pressure Measurement. (United States)

    Liu, Jiankun; Cheng, Hao-Min; Chen, Chen-Huan; Sung, Shih-Hsien; Moslehpour, Mohsen; Hahn, Jin-Oh; Mukkamala, Ramakrishna


    Most automatic cuff blood pressure (BP) measurement devices are based on oscillometry. These devices estimate BP from the envelopes of the cuff pressure oscillations using fixed ratios. The values of the fixed ratios represent population averages, so the devices may only be accurate in subjects with normal BP levels. The objective was to develop and demonstrate the validity of a patient-specific oscillometric BP measurement method. The idea of the developed method was to represent the cuff pressure oscillation envelopes with a physiologic model, and then estimate the patient-specific parameters of the model, which includes BP levels, by optimally fitting it to the envelopes. The method was investigated against gold standard reference BP measurements from 57 patients with widely varying pulse pressures. A portion of the data was used to optimize the patient-specific method and a fixed-ratio method, while the remaining data were used to test these methods and a current office device. The patient-specific method yielded BP root-mean-square-errors ranging from 6.0 to 9.3 mmHg. On an average, these errors were nearly 40% lower than the errors of each existing method. The patient-specific method may improve automatic cuff BP measurement accuracy. A patient-specific oscillometric BP measurement method was proposed and shown to be more accurate than the conventional method and a current device.

  7. Analysis of atmospheric concentrations of quinones and polycyclic aromatic hydrocarbons in vapour and particulate phases (United States)

    Delgado-Saborit, Juana Maria; Alam, Mohammed S.; Godri Pollitt, Krystal J.; Stark, Christopher; Harrison, Roy M.


    Polycyclic aromatic hydrocarbons (PAH) are often measured in studies of atmospheric chemistry or health effects of air pollution, due to their known human carcinogenicity. In recent years, PAH quinone derivatives have also become a focus of interest, primarily because they can contribute to oxidative stress. This work reports concentrations of 17 PAH and 15 quinones measured in air samples collected at a trafficked roadside. Data are presented for four compounds not previously reported in ambient air: 2-methyl-1,4-naphthoquinone, 2,6-di-tert-butyl-1,4-benzoquinone, methyl-1,4-benzoquinone and 2,3-dimethylanthraquinone, and a large vapour phase component is measured, not analysed in most earlier studies. Analyses are reported also for SRM 1649a and 1649b, including many compounds (8 for SRM 1649a and 12 for SRM 1649b) for which concentrations have not previously been reported. This work assesses the vapour/particle phase distribution of PAHs and quinones in relation to their molecular weight, vapour pressure, polarity and Henry's Law constant, finding that both molecular weight and vapour pressure (which are correlated) are good predictors of the partitioning.

  8. Oscillometric blood pressure measurements: A signal analysis (United States)

    Barbé, K.; Van Moer, W.; Lauwers, L.


    In this paper, the oscillometric waveform measured by automatic non-invasive blood pressure meters (NIBP) is analyzed by transforming the data from the time domain to the frequency domain. The signal's spectrum of the oscillometric waveform is in current literature badly understood or explored. The only known link between the oscillometric waveform and the blood pressure is the maximum of the oscillometry's envelope equalling the mean arterial pressure (MAP). This link is established under the assumption that the oscillometry is an AM-signal. Unfortunately, computing the MAP is difficult in practice due to the non-sinusoidal nature of the actual measured signals. In this paper, we construct the best AM-signal approximation of the oscillometry and explore its use to compute the MAP.

  9. Simultaneous retrieval of water vapour, temperature and cirrus clouds properties from measurements of far infrared spectral radiance over the Antarctic Plateau (United States)

    Di Natale, Gianluca; Palchetti, Luca; Bianchini, Giovanni; Del Guasta, Massimo


    The possibility separating the contributions of the atmospheric state and ice clouds by using spectral infrared measurements is a fundamental step to quantifying the cloud effect in climate models. A simultaneous retrieval of cloud and atmospheric parameters from infrared wideband spectra will allow the disentanglement of the spectral interference between these variables. In this paper, we describe the development of a code for the simultaneous retrieval of atmospheric state and ice cloud parameters, and its application to the analysis of the spectral measurements acquired by the Radiation Explorer in the Far Infrared - Prototype for Applications and Development (REFIR-PAD) spectroradiometer, which has been in operation at Concordia Station on the Antarctic Plateau since 2012. The code performs the retrieval with a computational time that is comparable with the instrument acquisition time. Water vapour and temperature profiles and the cloud optical and microphysical properties, such as the generalised effective diameter and the ice water path, are retrieved by exploiting the 230-980 cm-1 spectral band. To simulate atmospheric radiative transfer, the Line-By-Line Radiative Transfer Model (LBLRTM) has been integrated with a specifically developed subroutine based on the δ-Eddington two-stream approximation, whereas the single-scattering properties of cirrus clouds have been derived from a database for hexagonal column habits. In order to detect ice clouds, a backscattering and depolarisation lidar, co-located with REFIR-PAD has been used, allowing us to infer the position and the cloud thickness to be used in the retrieval. A climatology of the vertical profiles of water vapour and temperature has been performed by using the daily radiosounding available at the station at 12:00 UTC. The climatology has been used to build an a priori profile correlation to constrain the fitting procedure. An optimal estimation method with the Levenberg-Marquardt approach has been

  10. Pore Pressure Measurements Inside Rubble Mound Breakwaters

    DEFF Research Database (Denmark)

    Helgason, Einar; Burcharth, H. F.; Grüne, Joachim


    The present paper presents pore pressure measurements from large scale model tests performed at the Large Wave Channel, Hannover, Germany and small scale model test performed at the Hydraulic & Coastal Engineering Laboratory, Aalborg University, Denmark. Information on pore pressure attenuation...... and wave damping in the core and important for the scaling of core materials in small scale hydraulic models. The main objectives are to study and examine the wave damping in the core of rubble mound breakwater models. the acquired test results are compared with results available from the literature...

  11. Noninvasive measurement of central venous pressure (United States)

    Webster, J. G.; Mastenbrook, S. M., Jr.


    A technique for the noninvasive measurement of CVP in man was developed. The method involves monitoring venous velocity at a point in the periphery with a transcutaneous Doppler ultrasonic velocity meter while the patient performs a forced expiratory maneuver. The idea is the CVP is related to the value of pressure measured at the mouth which just stops the flow in the vein. Two improvements were made over the original procedure. First, the site of venous velocity measurement was shifted from a vein at the antecubital fossa (elbow) to the right external jugular vein in the neck. This allows for sensing more readily events occurring in the central veins. Secondly, and perhaps most significantly, a procedure for obtaining a curve of relative mean venous velocity vs mouth pressure was developed.

  12. Can painted glass felt or glass fibre cloth be used as vapour barrier?

    DEFF Research Database (Denmark)

    El-Khattam, Amira; Andersen, Mie Them; Hansen, Kurt Kielsgaard


    with a ventilated attic where the ceiling may be air tight but has no vapour barrier; post-insulation of the attic may cause the need for a vapour barrier. Placing a vapour barrier above the ceiling can be tiresome and it is difficult to ensure tightness. A simpler way is to paint a vapour barrier directly...... on the ceiling e.g. as an ordinary paint. This paper presents the results of an investigation of the water vapour resistance of surface treatments which are commonly used in-door. The water vapour resistance was measured by the cup method. Aerated concrete was investigated with and without various surface...

  13. Variability of water vapour in the Arctic stratosphere (United States)

    Thölix, Laura; Backman, Leif; Kivi, Rigel; Karpechko, Alexey Yu.


    This study evaluates the stratospheric water vapour distribution and variability in the Arctic. A FinROSE chemistry transport model simulation covering the years 1990-2014 is compared to observations (satellite and frost point hygrometer soundings), and the sources of stratospheric water vapour are studied. In the simulations, the Arctic water vapour shows decadal variability with a magnitude of 0.8 ppm. Both observations and the simulations show an increase in the water vapour concentration in the Arctic stratosphere after the year 2006, but around 2012 the concentration started to decrease. Model calculations suggest that this increase in water vapour is mostly explained by transport-related processes, while the photochemically produced water vapour plays a relatively smaller role. The increase in water vapour in the presence of the low winter temperatures in the Arctic stratosphere led to more frequent occurrence of ice polar stratospheric clouds (PSCs) in the Arctic vortex. We perform a case study of ice PSC formation focusing on January 2010 when the polar vortex was unusually cold and allowed large-scale formation of PSCs. At the same time a large-scale persistent dehydration was observed. Ice PSCs and dehydration observed at Sodankylä with accurate water vapour soundings in January and February 2010 during the LAPBIAT (Lapland Atmosphere-Biosphere facility) atmospheric measurement campaign were well reproduced by the model. In particular, both the observed and simulated decrease in water vapour in the dehydration layer was up to 1.5 ppm.

  14. Automatic Blood Pressure Measurements During Exercise (United States)

    Weaver, Charles S.


    Microprocessor circuits and a computer algorithm for automatically measuring blood pressure during ambulatory monitoring and exercise stress testing have been under development at SRI International. A system that records ECG, Korotkov sound, and arm cuff pressure for off-line calculation of blood pressure has been delivered to NASA, and an LSLE physiological monitoring system that performs the algorithm calculations in real-time is being constructed. The algorithm measures the time between the R-wave peaks and the corresponding Korotkov sound on-set (RK-interval). Since the curve of RK-interval versus cuff pressure during deflation is predictable and slowly varying, windows can be set around the curve to eliminate false Korotkov sound detections that result from noise. The slope of this curve, which will generally decrease during exercise, is the inverse of the systolic slope of the brachial artery pulse. In measurements taken during treadmill stress testing, the changes in slopes of subjects with coronary artery disease were markedly different from the changes in slopes of healthy subjects. Measurements of slope and O2 consumption were also made before and after ten days of bed rest during NASA/Ames Research Center bed rest studies. Typically, the maximum rate of O2 consumption during the post-bed rest test is less than the maximum rate during the pre-bed rest test. The post-bed rest slope changes differ from the pre-bed rest slope changes, and the differences are highly correlated with the drop in the maximum rate of O2 consumption. We speculate that the differences between pre- and post-bed rest slopes are due to a drop in heart contractility.

  15. Onsager heat of transport at the n-octane liquid vapour interface: Effects of altering the size of the vapour-gap and of adding helium (United States)

    Phillips, Leon F.


    Values of the Onsager heat of transport Q∗ measured at the n-octane liquid-vapour interface are consistent with the results of molecular dynamics calculations by Simon et al. [J.-M. Simon, S. Kjelstrup, D. Bedeaux, B. Hafskjold, J. Phys. Chem. B 108 (2004) 7186.] The measured value of Q∗ is independent of gas pressure but is affected by variations in the size of the vapour gap over which the temperature gradient is applied. Measurements with added helium indicate that Q∗ is negative for helium at the surface of n-octane, even though the enthalpy of solution is positive. The helium results can be understood on the basis of an existing model.

  16. Vapour galvanizing (Sherardizing) of copper with zinc

    Energy Technology Data Exchange (ETDEWEB)

    Wortelen, Dietbert; Bracht, Hartmut [Westfaelische Wilhelms-Universitaet Muenster (Germany); Natrup, Frank; Graf, Wolfram [Bodycote Waermebehandlung GmbH, Sprockhoevel (Germany)


    Using a vapour galvanizing technique called Sherardizing we investigated the growth kinetics and coefficients of zinc copper phases. For this purpose polished (OFHC)-copper plates and zinc powder have been sealed in quartz ampoules under inert gas atmospheres and annealed at a temperature range between 300 and 410 C. In order to study the coating thickness and the phase composition, cross sections were prepared, which have been analyzed by means of optical microscopy and scanning electron microscopy. We were able to demonstrate that the coating thickness is a function of the parabolic time law and that the formed coatings are composed of two layers referring to the ordered {beta}-CuZn and {gamma}-Cu{sub 5}Zn{sub 8}-phases. To enhance the coating quality, small amounts of ZnCl{sub 2} were added to the zinc powder. It was observed that the coating thickness decreased with increasing ZnCl{sub 2}. Experiments with variable Ar-pressure demonstrated a reduced coating growth with increasing pressures. Further measurements with ZnCl{sub 2} were performed to check whether an electrochemical mechanism is involved in the coating process.

  17. Principles of Blood Pressure Measurement - Current Techniques, Office vs Ambulatory Blood Pressure Measurement. (United States)

    Vischer, Annina S; Burkard, Thilo


    Blood pressure measurement has a long history and a crucial role in clinical medicine. Manual measurement using a mercury sphygmomanometer and a stethoscope remains the Gold Standard. However, this technique is technically demanding and commonly leads to faulty values. Automatic devices have helped to improve and simplify the technical aspects, but a standardised procedure of obtaining comparable measurements remains problematic and may therefore limit their validity in clinical practice. This underlines the importance of less error-prone measurement methods such as ambulatory or home blood pressure measurements and automated office blood pressure measurements. These techniques may help to uncover patients with otherwise unrecognised or overestimated arterial hypertension. Additionally these techniques may yield a better prognostic value.

  18. Water vapour variability and trends in the Arctic stratosphere (United States)

    Thölix, Laura; Kivi, Rigel; Backman, Leif; Karpechko, Alexey


    Water vapour in the upper troposphere-lower stratosphere (UTLS) is a radiatively and chemically important trace gas. Stratospheric water vapour also affects ozone chemistry through odd-hydrogen chemistry and formation of polar stratospheric clouds (PSC). Both transport and chemistry contribute to the extratropical lower stratospheric water vapour distribution and trends. The main sources of stratospheric water vapour are intrusion through the tropical tropopause and production from oxidation of methane. Accurate observations of UTLS water vapour are difficult to obtain due to the strong gradient in the water vapour profile over the tropopause. However, modelling the stratospheric water vapour distribution is challenging and accurate measurements are needed for model validation. Trends in Arctic water vapour will be analysed and explained in terms of contribution from different processes (transport and chemistry), using observations and chemistry transport model (CTM) simulations. Accurate water vapour soundings from Sodankylä will be used to study water vapour within the Arctic polar vortex, including process studies on formation of PSCs and dehydration. Water vapour profiles measured during the LAPBIAT atmospheric sounding campaign in Sodankylä in January 2010 indicated formation of ice clouds and dehydration. Effects on ozone chemistry will also be studied. Global middle atmospheric simulations have been performed with the FinROSE-ctm using ERA-Interim winds and temperatures. The FinROSE-ctm is a global middle atmosphere model that produces the distribution of 30 long-lived species and tracers and 14 short-lived species. The chemistry describes around 110 gas phase reactions, 37 photodissociation processes and the main heterogeneous reactions related to aerosols and polar stratospheric clouds.

  19. Hybrid Optical Unobtrusive Blood Pressure Measurements

    Directory of Open Access Journals (Sweden)

    Guangfei Zhang


    Full Text Available Blood pressure (BP is critical in diagnosing certain cardiovascular diseases such as hypertension. Some previous studies have proved that BP can be estimated by pulse transit time (PTT calculated by a pair of photoplethysmography (PPG signals at two body sites. Currently, contact PPG (cPPG and imaging PPG (iPPG are two feasible ways to obtain PPG signals. In this study, we proposed a hybrid system (called the ICPPG system employing both methods that can be implemented on a wearable device, facilitating the measurement of BP in an inconspicuous way. The feasibility of the ICPPG system was validated on a dataset with 29 subjects. It has been proved that the ICPPG system is able to estimate PTT values. Moreover, the PTT measured by the new system shows a correlation on average with BP variations for most subjects, which could facilitate a new generation of BP measurement using wearable and mobile devices.

  20. Measuring elevated intracranial pressure through noninvasive methods

    DEFF Research Database (Denmark)

    Kristiansson, Helena; Nissborg, Emelie; Bartek, Jiri


    techniques available. Several methods for noninvasive measuring of elevated ICP have been proposed: radiologic methods including computed tomography and magnetic resonance imaging, transcranial Doppler, electroencephalography power spectrum analysis, and the audiological and ophthalmological techniques......Elevated intracranial pressure (ICP) is an important cause of secondary brain injury, and a measurement of ICP is often of crucial value in neurosurgical and neurological patients. The gold standard for ICP monitoring is through an intraventricular catheter, but this invasive technique...... is associated with certain risks. Intraparenchymal ICP monitoring methods are considered to be a safer alternative but can, in certain conditions, be imprecise due to zero drift and still require an invasive procedure. An accurate noninvasive method to measure elevated ICP would therefore be desirable...

  1. Virucidal efficacy of hydrogen peroxide vapour disinfection

    NARCIS (Netherlands)

    Tuladhar, E.; Terpstra, P.; Koopmans, M.; Duizer, E.


    Background: Viral contamination of surfaces is thought to be important in transmission. Chemical disinfection can be an effective means of intervention, but little is known about the virucidal efficacy of hydrogen peroxide vapour (HPV) against enteric and respiratory viruses. Aim: To measure the

  2. Plasma assisted measurements of alkali metal concentrations in pressurized combustion processes

    Energy Technology Data Exchange (ETDEWEB)

    Hernberg, R.; Haeyrinen, V. [Tampere Univ. of Technology (Finland). Dept. of Physics


    The plasma assisted method for continuous measurement of alkali concentrations in product gas flows of pressurized energy processes will be tested and applied at the 1.6 MW PFBC/G facility at Delft University of Technology in the Netherlands. During the reporting period the alkali measuring device has been tested under pressurized conditions at VTT Energy, DMT, Foster-Wheeler Energia and ABB Carbon. Measurements in Delft will be performed during 1996 after installation of the hot gas filter. The original plan for measurements in Delft has been postponed due to schedule delays in Delft. The results are expected to give information about the influence of different process conditions on the generation of alkali vapours, the comparison of different methods for alkali measurement and the specific performance of our system. This will be the first test of the plasma assisted measurement method in a gasification process. The project belongs to the Joule II extension program under contract JOU2-CT93-0431. (author)

  3. Improved water vapour spectroscopy in the 4174–4300 cm−1 region and its impact on SCIAMACHY HDO/H2O measurements

    Directory of Open Access Journals (Sweden)

    R. A. Scheepmaker


    Full Text Available The relative abundance of the heavy water isotopologue HDO provides a deeper insight into the atmospheric hydrological cycle. The SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY allows for global retrievals of the ratio HDO/H2O in the 2.3 micron wavelength range. However, the spectroscopy of water lines in this region remains a large source of uncertainty for these retrievals. We therefore evaluate and improve the water spectroscopy in the range 4174–4300 cm−1 and test if this reduces systematic uncertainties in the SCIAMACHY retrievals of HDO/H2O. We use a laboratory spectrum of water vapour to fit line intensity, air broadening and wavelength shift parameters. The improved spectroscopy is tested on a series of ground-based high resolution FTS spectra as well as on SCIAMACHY retrievals of H2O and the ratio HDO/H2O. We find that the improved spectroscopy leads to lower residuals in the FTS spectra compared to HITRAN 2008 and Jenouvrier et al. (2007 spectroscopy, and the retrievals become more robust against changes in the retrieval window. For both the FTS and SCIAMACHY measurements, the retrieved total H2O columns decrease by 2–4% and we find a negative shift of the HDO/H2O ratio, which for SCIAMACHY is partly compensated by changes in the retrieval setup and calibration software. The updated SCIAMACHY HDO/H2O product shows somewhat steeper latitudinal and temporal gradients and a steeper Rayleigh distillation curve, strengthening previous conclusions that current isotope-enabled general circulation models underestimate the variability in the near-surface HDO/H2O ratio.

  4. Measurements to check vapour recovery systems of public retail stations in Hamburg (Phase 1); Messaktion zur Ueberpruefung von Gasrueckfuehrungssystemen an oeffentlichen Tankstellen in der Freien und Hansestadt Hamburg (Phase 1)

    Energy Technology Data Exchange (ETDEWEB)

    Altmann, B.R. [Deutsche Wissenschaftliche Gesellschaft fuer Erdoel, Erdgas und Kohle e.V., Hamburg (Germany); Golgert, R. [Gesundheits- und Umweltamt, Hamburg (Germany). Bezirksamt Wandsbek; Okelmann, J. [Umweltbehoerde, Hamburg (Germany). Amt fuer Immissionsschutz und Betriebe; Schenck, H.G. [Gesundheits- und Umweltamt, Hamburg (Germany). Bezirksamt Eimsbuettel, Abt. fuer Umweltschutz


    DGMK jointly with the local authorities of health and environment, in close co-operation with the environmental authorities of the city of Hamburg, are thoroughly examining the vapour recovery systems at all public service stations in Hamburg. In phase I 50 sites were examined in August/September 1999 by several measuring methods called liquid-measurement, liquid-check, quick-check (UPA 50/Flo-Tester) and dry-measurement procedure. They delivered proportions and causes of bad performing and defective devices leading to appropriate maintenance. The dry-measurement procedure commonly used with regular checks by itself is not satisfactory to prove overall performance of the vapour recovery equipment. It should always be supplemented by a liquid-check procedure in order to ensure that the assigned vapour pumps work. As the dry-measurement procedure simulates a fuel flow it cannot detect such defects. Complete breakdowns of vapour recovery systems can be localised reliably with the quick check devices UPA 50/Flo-Tester. But due to high error tolerances, quick check devices are not suitable for quantitative measurement of vapour recovery rates on service stations. (orig.) [German] Die DGMK fuehrt unter Beteiligung der Umweltbehoerde Hamburg zusammen mit den Gesundheits- und Umweltaemtern der Bezirke und den Tankstellenbetreibern in einem Gemeinschaftsprojekt detaillierte Untersuchungen der Gasrueckfuehrungssysteme an allen Hamburger Tankstellen durch. Ziel der Untersuchung ist die Ueberpruefung und Verbesserung des technischen Zustandes der Gasrueckfuehrsysteme an allen Hamburger Tankstellen. Darueber hinaus sollen genaue Kenntnisse ueber die Verlaesslichkeit von gaengigen Messverfahren zur Ueberpruefung von Gasrueckfuehrsystemen erworben werden. In der Phase I wurden an 50 Tankstellen Messungen im August/September 1999 unter Anwendung des Nassmessverfahrens, des Trockenmessverfahrens, der Schnelltester (Flo-Tester und UPA 50) sowie der Nasskontrolle zur Ueberpruefung

  5. 21 CFR 890.1600 - Intermittent pressure measurement system. (United States)


    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Intermittent pressure measurement system. 890.1600 Section 890.1600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Intermittent pressure measurement system. (a) Identification. An intermittent pressure measurement system is an...

  6. 21 CFR 870.1130 - Noninvasive blood pressure measurement system. (United States)


    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Noninvasive blood pressure measurement system. 870... SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Diagnostic Devices § 870.1130 Noninvasive blood pressure measurement system. (a) Identification. A noninvasive blood pressure measurement...

  7. Relating external compressing pressure to mean arterial pressure in non-invasive blood pressure measurements. (United States)

    Chin, K Y; Panerai, R B


    Arterial volume clamping uses external compression of an artery to provide continuous non-invasive measurement of arterial blood pressure. It has been assumed that mean arterial pressure (MAP) corresponds to the point where unloading leads to the maximum oscillation of the arterial wall as reflected by photoplethysmogram (PPG), an assumption that has been challenged. Five subjects were recruited for the study (three males, mean age (SD) = 32 (15) years). The PPG waveform was analysed to identify the relationship between the external compressing pressure, PPG pulse amplitude and MAP. Two separate tests were carried out at compression step intervals of 10 mmHg and 2 mmHg, respectively. No significant differences were found between the two tests. The bias between the compressing pressure and the MAP was -4.7 ± 5.63 mmHg (p < 0.001) showing a normal distribution. Further research is needed to identify optimal algorithms for estimation of MAP using PPG associated with arterial compression.

  8. Organic Electroluminescent Sensor for Pressure Measurement

    Directory of Open Access Journals (Sweden)

    Tomohide Niimi


    Full Text Available We have proposed a novel concept of a pressure sensor called electroluminescent pressure sensor (ELPS based on oxygen quenching of electroluminescence. The sensor was fabricated as an organic light-emitting device (OLED with phosphorescent dyes whose phosphorescence can be quenched by oxygenmolecules, and with a polymer electrode which permeates oxygen molecules. The sensor was a single-layer OLED with Platinum (II octaethylporphine (PtOEP doped into poly(vinylcarbazole (PVK as an oxygen sensitive emissive layer and poly(3,4-ethylenedioxythiophene mixed with poly(styrenesulfonate (PEDOT:PSS as an oxygen permeating polymer anode. The pressure sensitivity of the fabricated ELPS sample was equivalent to that of the sensor excited by an illumination light source. Moreover, the pressure sensitivity of the sensor is equivalent to that of conventional pressure-sensitive paint (PSP, which is an optical pressure sensor based on photoluminescence.

  9. High-quality Ge/Si{sub 0.4}Ge{sub 0.6} multiple quantum wells for photonic applications: growth by reduced pressure chemical vapour deposition and structural characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xuechao; Myronov, M; Dobbie, A; Morris, R J H; Leadley, D R, E-mail: [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom)


    Strain-symmetrized Ge/SiGe multiple quantum wells have been grown on a thin (2.1 {mu}m) relaxed Si{sub 0.2}Ge{sub 0.8}/Ge/Si(1 0 0) virtual substrate (VS) by reduced pressure chemical vapour deposition. Such structures are of interest in optoelectronic applications for which the structural integrity of the quantum well layers, after processing, is critical. The layer composition, thickness and interface quality have been studied for wafers both as-grown and after annealing between 550 and 700 deg. C. Transmission electron microscopy indicated precise thickness control of {+-}0.1 nm and sharp abruptness between the Ge QWs and SiGe barrier layers. A smooth surface was observed, with an average rms roughness of 1.5 {+-} 0.1 nm determined by atomic force microscopy. High-resolution x-ray diffraction (HR-XRD) indicated that both the QWs and barriers were fully strained compared with the relaxed VS. The thermal stability of the epilayers was investigated both by ultra low energy secondary ion mass spectroscopy of post-growth annealed layers and by in situ annealing in a high temperature HR-XRD stage. No obvious interdiffusion and strain relaxation was observed provided the annealing temperature was below 600 deg. C, but significant atomic rearrangement was evident for greater thermal budgets, thereby setting an upper processing temperature for this type of structure.

  10. Blood Pressure Measurement: Clinic, Home, Ambulatory, and Beyond (United States)

    Drawz, Paul E.; Abdalla, Mohamed; Rahman, Mahboob


    Blood pressure has traditionally been measured in the clinic setting using the auscultory method and a mercury sphygmomanometer. Technological advances have led to improvements in measuring clinic blood pressure and allowed for measuring blood pressures outside the clinic. This review outlines various methods for evaluating blood pressure and the clinical utility of each type of measurement. Home blood pressures and 24 hour ambulatory blood pressures have improved our ability to evaluate risk for target organ damage and hypertension related morbidity and mortality. Measuring home blood pressures may lead to more active participation in health care by patients and has the potential to improve blood pressure control. Ambulatory blood pressure monitoring enables the measuring nighttime blood pressures and diurnal changes, which may be the most accurate predictors of risk associated with elevated blood pressure. Additionally, reducing nighttime blood pressure is feasible and may be an important component of effective antihypertensive therapy. Finally, estimating central aortic pressures and pulse wave velocity are two of the newer methods for assessing blood pressure and hypertension related target organ damage. PMID:22521624

  11. Non-invasive blood pressure measurement in mice. (United States)

    Feng, Minjie; DiPetrillo, Keith


    Hypertension is a leading cause of heart attack, stroke, and kidney failure and represents a serious medical issue worldwide. The genetic basis of hypertension is well-established, but few causal genes have been identified thus far. Non-invasive blood pressure measurements are a critical component of high-throughput genetic studies to identify genes controlling blood pressure. Whereas this technique is fairly routine for blood pressure measurements in rats, non-invasive blood pressure measurement in mice has proven to be more challenging. This chapter describes an experimental protocol measuring blood pressure in mice using a CODA non-invasive blood pressure monitoring system. This method enables accurate blood pressure phenotyping in mice for linkage or mutagenesis studies, as well as for other experiments requiring high-throughput blood pressure measurement.

  12. Retention curves measured using pressure plate and pressure membrane apparatus

    DEFF Research Database (Denmark)

    Hansen, Morten Hjorslev

    This report presents a proposal for a test method for the measurement of the retention curve, especially in the high moisture content range, and the pore size distribution of building materials. The test method includes the measurement of apparent density, solid density, and open porosity. The re...

  13. Measuring Fluctuating Pressures With Recessed Gauges (United States)

    Parrott, Tony L.; Jones, Michael G.


    Report discusses use of pressure gauges mounted in recesses in interior wall of model scramjet engine. Consists of brief memorandum plus excerpts from NASA Technical Paper 3189, "Unsteady Pressure Loads In A Generic High-Speed Engine Model." Focuses mainly on factors affecting accuracy of gauge readings.

  14. Retention curves measured using pressure plate and pressure membrane apparatus

    DEFF Research Database (Denmark)

    Hansen, Morten Hjorslev

    This report presents a proposal for a test method for the measurement of the retention curve, especially in the high moisture content range, and the pore size distribution of building materials. The test method includes the measurement of apparent density, solid density, and open porosity. The re....... The results of an interlaboratory comparison of the test method are presented and analysed along the guidelines given in ISO 5725-5.......This report presents a proposal for a test method for the measurement of the retention curve, especially in the high moisture content range, and the pore size distribution of building materials. The test method includes the measurement of apparent density, solid density, and open porosity...

  15. [An integrated system of blood pressure measurement with bluetooth communication]. (United States)

    Wang, Wei; Wang, Jing; Sun, Hongyang; Xu, Zuyang; Chai, Xinyu


    The development of the integrated blood pressure system with bluetooth communication function is introduced. Experimental results show that the system can complete blood pressure measurement and data transmission wireless effectively, which can be used in m-Health in future.

  16. Auscultatory versus oscillometric measurement of blood pressure in octogenarians

    DEFF Research Database (Denmark)

    Rosholm, Jens-Ulrik; Pedersen, Sidsel Arnspang; Matzen, Lars


    Auscultatory measurement using a sphygmomanometer has been the predominant method for clinical estimation of blood pressure, but it is now rapidly being replaced by oscillometric measurement.......Auscultatory measurement using a sphygmomanometer has been the predominant method for clinical estimation of blood pressure, but it is now rapidly being replaced by oscillometric measurement....

  17. Measuring Blast-Related Intracranial Pressure Within the Human Head (United States)


    4 Pressure sensors Commercially available sensors from Endevco (models 8515C and 8530C), FISO Technologies (FOP-MIV model) and PCB...monitoring of the ambient overpressure at the target was provided by a pressure probe that contained two Endevco sensors placed frontally and sideon with...pressure sensor measuring the static component of the shock wave in air along the tube; (B) pressure sensor using Endevco sensor to measure static and

  18. Reevaluation of the needle method for measuring interstitial fluid pressure. (United States)

    Brace, R A; Guyton, A C; Taylor, A E


    Inserting a needle into subcutaneous spaces should allow a subatmospheric pressure to be measured if interstitial fluid pressure is truly negative as measured by the capsule and wick techniques. Previous needle measurements of interstitial fluid pressure have produced a positive value, but in most instances fluid has been injected into the tissues prior to recording of pressure. Therefore, we measured subcutaneous needle pressure in anesthetized dogs without fluid injection into the tissues. Approximately 30 min are required for an equilibrium pressure after insertion of the needle. The mean 30-min pressure was 4.6 +/- 0.5 (SE) mmHg (n equals 41). With observable edema, interstitial fluid pressures as measured with the needle were always positive. However, the needle method for continuous recording of pressure lacks rapid sensitivity to changes in tissue fluid pressures. In order to develop a needle method that would follow changes in interstitial fluid pressure, 0.5-1 mul of saline was injected into or withdrawn from the tissue. With this method, pressure plateaued in 10-20 min. This plateau pressure increased with tissue hydration and decreased with dehydration.

  19. One year observation of water vapour isotopic composition at Ivittuut, Southern Greenland (United States)

    Bonne, Jean-Louis; Masson-Delmotte, Valérie; Delmotte, Marc; Cattani, Olivier; Sodemann, Harald; Risi, Camille


    In September 2011, an automatic continuous water vapour isotopic composition monitoring instrument has been installed in the atmospheric station of Ivittuut (61.21° N, 48.17° W), southern Greenland. Precipitation has been regularly sampled on site at event to weekly scales and analysed in our laboratory for isotopic composition. Meteorological parameters (temperature, pressure, relative humidity, wind speed and direction) and atmospheric composition (CO2, CH4, Atmospheric Potential Oxygen) are also continuously monitored at Ivittuut. The meteorological context of our observation period will be assessed by comparison with the local climatology. The water vapour analyser is a Picarro Wavelength Scanned Cavity Ring-Down Spectrometer (WS-CRDS, model L2120i). It is automatically and regularly calibrated on the VSMOW scale using measurements of the isotopic composition of vaporized reference water standards using the Picarro Syringe Delivery Module (SDM). As measurements are sensitive to humidity level, an experimentally estimated calibration response function is used to correct our isotopic measurements. After data treatment, successive isotopic measurements of reference waters have a standard deviation of around 0.35 per mil for δ18O and 2.3 per mil for δD. Our instrumentation protocol and data quality control method will be presented, together with our one year δ18O, δD and d-excess measurements in water vapour and precipitation. The relationship between surface water vapour isotopic composition and precipitation isotopic composition will be investigated based on a distillation model. Specific difficulties linked to our low maintenance remote station will also be discussed. The processes responsible for the synoptic variability of Ivittuut water vapour isotopic composition will be investigated by comparing our observational dataset with (i) atmospheric back-trajectories and (ii) results from an isotopically-enabled atmospheric general circulation model (AGCM

  20. Vapour pressure of components made by the presence of HgS(s,alpha) in an oil/gas reservoir and consequences for the produced gas

    Energy Technology Data Exchange (ETDEWEB)

    Oestvold, T.; Gustavsen, Oe.; Grande, K.; Aas, N.; Olsvik, Mimmi Kjetsaa


    A thermodynamic analysis is presented on how components made from HgS (s,alpha), existing in a oil/gas reservoir, will distribute themselves between gas, water, liquid and solid components as a function of temperature and pressure. The consequence of the formation of mercury containing components on gas injection and on gas quality is discussed. Since equilibrium is established in the model calculation, other gas components in the gas phase and components in condensed phases present will also influence the composition of the gas. Six cases are considered in the calculation: 1) HgS(s,alpha) - Ar(g), 2) HgS(s,alpha) - Ar (g) - water with 10-4 molal NaCl at pH = 7, 3) HgS(s,alpha) - CH{sub 4}(g), 4) HgS(s,alpha) - CH{sub 4} (g) - water with 10-4 molal NaCl at pH = 7 and 5) HgS(s,alpha) - natural gas - water with 10-4 molal NaCl at pH = 7, 6) HgS(s,alpha) - natural gas - water with 10-4 molal NaCl and 5*10-5 molal NO-3- at pH = 7. When HgS(s,alpha) is present in an oil reservoir at 170 deg C and 200 bar, these calculations show that the major components formed are: H{sub 2}(g), H{sub 2}S(g), Hg(l) and Hg(g) together with carbon. Mercury in the gas phase in the cases 1) is 4*10-7 bar and is determined by the evaporation and decomposition HgS(g) in the reservoir. In case 2) P{sub Hg} = 5.7*10-4 bar mainly determined by the formation of sulphate in the water phase. In the cases 3), 4) and 5) these calculations show that the major components formed are: H{sub 2}(g), H{sub 2}S(g), Hg(l) and Hg(g) together with carbon, and the gas phase is dominated by Hg(g) at approx. *10-3 bar. The water phase may contain Hg(CH{sub 3}NH{sub 2}){sub 2}2+ if NO{sub 3}- for some reasons is introduced into the formation water, and the very carcinogenic dimethyl mercury compound, C{sub 2}HgH{sub 6}, can be formed in the gas phase. Both compounds, however, in insignificant low concentration/partial pressure. (Author)

  1. Ionic conductivity measurements of zirconia under pressure using impedance spectroscopy

    CERN Document Server

    Takebe, H; Ohtaka, O; Fukui, H; Yoshiasa, A; Yamanaka, T; Ota, K; Kikegawa, T


    We have set up an electrical conductivity measurement system under high-pressure and high-temperature conditions with a multi-anvil high-pressure apparatus using an AC complex impedance method. With this system, we have successfully measured the electrical conductivity of stabilized ZrO sub 2 (Y sub 2 O sub 3 -ZrO sub 2 solid solution) under pressures up to 5 GPa in the temperature range from 300 to 1200 K. The electrical conductivities obtained under pressure are compatible with those of previous results measured at ambient pressure.

  2. Automated measurement of pressure injury through image processing. (United States)

    Li, Dan; Mathews, Carol


    To develop an image processing algorithm to automatically measure pressure injuries using electronic pressure injury images stored in nursing documentation. Photographing pressure injuries and storing the images in the electronic health record is standard practice in many hospitals. However, the manual measurement of pressure injury is time-consuming, challenging and subject to intra/inter-reader variability with complexities of the pressure injury and the clinical environment. A cross-sectional algorithm development study. A set of 32 pressure injury images were obtained from a western Pennsylvania hospital. First, we transformed the images from an RGB (i.e. red, green and blue) colour space to a YCb Cr colour space to eliminate inferences from varying light conditions and skin colours. Second, a probability map, generated by a skin colour Gaussian model, guided the pressure injury segmentation process using the Support Vector Machine classifier. Third, after segmentation, the reference ruler - included in each of the images - enabled perspective transformation and determination of pressure injury size. Finally, two nurses independently measured those 32 pressure injury images, and intraclass correlation coefficient was calculated. An image processing algorithm was developed to automatically measure the size of pressure injuries. Both inter- and intra-rater analysis achieved good level reliability. Validation of the size measurement of the pressure injury (1) demonstrates that our image processing algorithm is a reliable approach to monitoring pressure injury progress through clinical pressure injury images and (2) offers new insight to pressure injury evaluation and documentation. Once our algorithm is further developed, clinicians can be provided with an objective, reliable and efficient computational tool for segmentation and measurement of pressure injuries. With this, clinicians will be able to more effectively monitor the healing process of pressure injuries

  3. Methods of Blood Pressure Measurement in the ICU (United States)

    Lehman, Li-wei H.; Saeed, Mohammed; Talmor, Daniel; Mark, Roger; Malhotra, Atul


    Objective Minimal clinical research has investigated the significance of different blood pressure monitoring techniques in the ICU and whether systolic vs. mean blood pressures should be targeted in therapeutic protocols and in defining clinical study cohorts. The objectives of this study are to compare real-world invasive arterial blood pressure with noninvasive blood pressure, and to determine if differences between the two techniques have clinical implications. Design We conducted a retrospective study comparing invasive arterial blood pressure and noninvasive blood pressure measurements using a large ICU database. We performed pairwise comparison between concurrent measures of invasive arterial blood pressure and noninvasive blood pressure. We studied the association of systolic and mean invasive arterial blood pressure and noninvasive blood pressure with acute kidney injury, and with ICU mortality. Setting Adult intensive care units at a tertiary care hospital. Patients Adult patients admitted to intensive care units between 2001 and 2007. Interventions None. Measurements and Main Results Pairwise analysis of 27,022 simultaneously measured invasive arterial blood pressure/noninvasive blood pressure pairs indicated that noninvasive blood pressure overestimated systolic invasive arterial blood pressure during hypotension. Analysis of acute kidney injury and ICU mortality involved 1,633 and 4,957 patients, respectively. Our results indicated that hypotensive systolic noninvasive blood pressure readings were associated with a higher acute kidney injury prevalence (p = 0.008) and ICU mortality (p invasive arterial blood pressure in the same range (≤70 mm Hg). Noninvasive blood pressure and invasive arterial blood pressure mean arterial pressures showed better agreement; acute kidney injury prevalence (p = 0.28) and ICU mortality (p = 0.76) associated with hypotensive mean arterial pressure readings (≤60 mm Hg) were independent of measurement technique

  4. Acoustic sensor for remote measuring of pressure

    Directory of Open Access Journals (Sweden)

    Kataev V. F.


    Full Text Available The paper deals with sensors based on delay lines on surface acoustic waves (SAW, having a receiving-emitting and a reflective interdigital transducers (IDT. The dependence of the reflection coefficient of SAW on type and intensity of the load was studied. The authors propose a composite delay line in which the phase of the reflection coefficient depends on the pressure. Pressure leads to a shift of the reflective IDT relative to the transceiver, because they are located on different substrates. The paper also presents functional diagrams of the interrogator.

  5. Indirect Measurement of Left Ventricular EndDiastolic Pressure in ...

    African Journals Online (AJOL)

    Pulmonary artery diastolic and pulmonary capillary wedge mean pressures were measured in 30 patients with congestive cardiomyopathy and in 30 patients with constrictive pericarditis. These measurements were compared with left ventricular end-diastolic pressure (LVEDP) to assess their value as indirect measurements ...


    African Journals Online (AJOL)

    measurement“. non-invasive blood pressure measurement is the norm in routine clinical practice. Non-invasive blood pressure (NIBP) measurement is an easy and reasonably reliable method of clinical evaluation and monitoring of patients. The measurement may be achieved by uuscultatory or oscillometric methods. The.

  7. Compressibility measurements of gases using externally heated pressure vessels. (United States)

    Presnall, D. C.


    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.

  8. Blood pressure and anthropometric measurements in healthy ...

    African Journals Online (AJOL)

    To describe blood pressure and its relationship to weight and height in healthy newly enrolled school entrants in. Jos, Plateau State ... 10.0) mmHg, respectively, and were significantly higher in private school pupils compared with public school pupils (97.1 (SD ..... as young as 5 years of age.12 Gender and race do not have.

  9. Molecular concentrators measure colloid osmotic pressure

    African Journals Online (AJOL)


    Apr 22, 1981 ... the forces involved in capillary filtration on a com- parative basis. Although various formulae have been ... membrane fracture during assembly with resultant pressure leakage and thus underestimation of C.O.P. If ... Water and dissolved molecules of molecular mass less than 10 000 are thus removed and ...

  10. Validation of an Endoscopic Fibre-Optic Pressure Sensor for Noninvasive Measurement of Variceal Pressure (United States)

    Sun, Bin; Kong, De-Run; Li, Su-Wen; Yu, Dong-Feng; Wang, Ging-Jing; Yu, Fang-Fang; Wu, Qiong; Xu, Jian-Ming


    In this study, the authors have developed endoscopic fibre-optic pressure sensor to detect variceal pressure and presented the validation of in vivo and in vitro studies, because the HVPG requires catheterization of hepatic veins, which is invasive and inconvenient. Compared with HVPG, it is better to measure directly the variceal pressure without puncturing the varices in a noninvasive way. PMID:27314010

  11. Anaesthetic machine pipeline inlet pressure gauges do not always measure pipeline pressure. (United States)

    Craig, D B; Longmuir, J


    Some anaesthetic gas machines have pipeline inlet pressure gauges which indicate the higher of either pipeline pressure, or machine circuit pressure (the pressure distal to the pressure reducing valve, and proximal to the flowmeter control valve). Failure by the operator to appreciate this feature may in specific circumstances lead to a delayed appreciation of pipeline malfunction or disconnection. The Canadian Standards Association Z168.3-M1980 Anaesthetic Gas Machine Standard requires pipeline inlet gauges which measure only pipeline (hose) pressure. Existing machines should be modified to accommodate this requirement.

  12. Enhancements in Photon Pressure Measurements Using a Solar Simulator (United States)

    Gray, P. A.; Edwards, D. L.; Carruth, M. R., Jr.; Munafo, Paul (Technical Monitor)


    Initial proof of concept photon momentum measurements were reported at the AIAA Conference in Reno Nevada, January 8-11, 2001. That presentation verified that photon pressure on a simulated solar sail material can be measured under high vacuum conditions using a full spectrum solar simulator and a vacuum compatible force measurement system. Modifications to this test system were implemented to enhance the accuracy of the photon pressure measurement. This paper describes the photon pressure measurement technique and modifications to increase the measurement accuracy using a candidate sail material, aluminized Mylar.

  13. Pressure Change Measurement Leak Testing Errors

    Energy Technology Data Exchange (ETDEWEB)

    Pryor, Jeff M [ORNL; Walker, William C [ORNL


    A pressure change test is a common leak testing method used in construction and Non-Destructive Examination (NDE). The test is known as being a fast, simple, and easy to apply evaluation method. While this method may be fairly quick to conduct and require simple instrumentation, the engineering behind this type of test is more complex than is apparent on the surface. This paper intends to discuss some of the more common errors made during the application of a pressure change test and give the test engineer insight into how to correctly compensate for these factors. The principals discussed here apply to ideal gases such as air or other monoatomic or diatomic gasses; however these same principals can be applied to polyatomic gasses or liquid flow rate with altered formula specific to those types of tests using the same methodology.

  14. Design and Development of a Pressure Transducer for High Hydrostatic Pressure Measurements up to 200 MPa (United States)

    Kumar, Anuj; Yadav, Sanjay; Agarwal, Ravinder


    A number of pressure transducers, based on strain gauge, capacitance/inductance type, frequency resonators, are commercially available and are being used for sensing and producing an electrical output proportional to applied pressure. These sensors have their own advantages and limitations due to operational ease, measurement uncertainty and the costs. Strain gauge type transducers are now well established devices for accurate and precise measurement of pressure within measurement uncertainty up to 0.1 % of full scale. In the present research work, an indigenous strain gauge pressure transducer has been designed, developed, tested and calibrated for pressure measurement up to 200 MPa. The measurement uncertainty estimated using the pressure transducer was found better than 0.1 % of full scale. This transducer was developed using four foil type strain gauges, bonded, two in axial direction while other two in radial direction, to the controlled stress zones of a tubular maraging steel active cylinder working also as diaphragm. The strain gages were then connected to a Wheatstone bridge arrangement to measure stress generated strains. The pressure was applied through matching connector designed in the same tubular transducer active element. The threaded unique design in a single piece through collar, ferule and tubing arrangement provides leak proof pressure connections with external devices without using additional seals. The calibration and performance checking of the pressure transducer was carried out using dead weight type national pressure standard using the internationally accepted calibration procedure.

  15. Interactions of fission product vapours with aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Benson, C.G.; Newland, M.S. [AEA Technology, Winfrith (United Kingdom)


    Reactions between structural and reactor materials aerosols and fission product vapours released during a severe accident in a light water reactor (LWR) will influence the magnitude of the radiological source term ultimately released to the environment. The interaction of cadmium aerosol with iodine vapour at different temperatures has been examined in a programme of experiments designed to characterise the kinetics of the system. Laser induced fluorescence (LIF) is a technique that is particularly amenable to the study of systems involving elemental iodine because of the high intensity of the fluorescence lines. Therefore this technique was used in the experiments to measure the decrease in the concentration of iodine vapour as the reaction with cadmium proceeded. Experiments were conducted over the range of temperatures (20-350{sup o}C), using calibrated iodine vapour and cadmium aerosol generators that gave well-quantified sources. The LIF results provided information on the kinetics of the process, whilst examination of filter samples gave data on the composition and morphology of the aerosol particles that were formed. The results showed that the reaction of cadmium with iodine was relatively fast, giving reaction half-lives of approximately 0.3 s. This suggests that the assumption used by primary circuit codes such as VICTORIA that reaction rates are mass-transfer limited, is justified for the cadmium-iodine reaction. The reaction was first order with respect to both cadmium and iodine, and was assigned as pseudo second order overall. However, there appeared to be a dependence of aerosol surface area on the overall rate constant, making the precise order of the reaction difficult to assign. The relatively high volatility of the cadmium iodide formed in the reaction played an important role in determining the composition of the particles. (author) 23 figs., 7 tabs., 22 refs.

  16. A new method of non-invasive blood pressure measurement (United States)

    Gu, Liangling; Yang, Yongming; Yu, Chengbo; Guo, Qiaohui; Zhu, Gang


    Blood pressure reflects a person's health.It is proposed here that the method of detecting blood pressure may be the key to improving the precision of blood pressure measurements. The oscillometric blood pressure measurement technique is widely used in automatic blood pressure measurement instruments correctly. A method of blood pressure measurement by oscillometric method is first presented. In the oscillometric method, the basic principle of the "feature point" method and the "amplitude characteristic ratios" method is also explained and discussed here. A new method of blood pressure measurement, namely the coefficient difference comparative method, is proposed here,which is based on the feature point method and amplitude characteristic ratios method. The method is proved both effective and reliable through the analysis of many cases and clinical tests. Utilizing Visual C++, software for this new and novel method was developed and passed criterion simulation apparatus test. When applied in hospital situation, its error was +/-5%. It is concluded that the oscillometric blood pressure measurement method can provide better means of blood pressure measurements reference for doctors.

  17. Innovations in plantar pressure and foot temperature measurements in diabetes

    NARCIS (Netherlands)

    Bus, S. A.


    Plantar pressure and temperature measurements in the diabetic foot primarily contribute to identifying abnormal values that increase risk for foot ulceration, and they are becoming increasingly more integrated in clinical practice and daily life of the patient. While plantar pressure measurements

  18. Chalcogenoether complexes of Nb(v) thio- and seleno-halides as single source precursors for low pressure chemical vapour deposition of NbS2 and NbSe2 thin films. (United States)

    Chang, Yao-Pang; Hector, Andrew L; Levason, William; Reid, Gillian


    NbSCl3 was obtained via reaction of NbCl5 with S(SiMe3)2 in anhydrous CH2Cl2, whilst in MeCN solution the same reaction gives [NbSCl3(MeCN)2]. [NbSeCl3(MeCN)2] was obtained similarly from NbCl5 with Se(SiMe3)2. The chalcogenoether complexes, [NbSCl3(ER2)] (E = S: R = Me, nBu; E = Se: R = nBu), were obtained from reaction of NbCl5, ER2 and S(SiMe3)2 in CH2Cl2. The structure of the [Nb2S2Cl6(SMe2)2] reveals a Cl-bridged dimer with the SMe2 ligands disposed syn. The Cl bridges are highly asymmetric, with the long Nb-Cl bond trans Nb[double bond, length as m-dash]S. The complexes, [NbSCl3(L-L)] (L-L = MeSCH2CH2SMe, MeS(CH2)3SMe, iPrSCH2CH2SiPr, MeSe(CH2)3SeMe and nBuS(CH2)3SnBu), were obtained from reaction of L-L with preformed [NbSCl3(MeCN)2]. The structures of the Me-substituted complexes reveal distorted octahedral monomers with the neutral ligands trans to S/Cl. Solution 1H and 77Se{1H} NMR data showed that the neutral ligands are partially dissociated and undergoing fast exchange at ambient temperatures in CH2Cl2 solution, consistent with weak Lewis acidity for NbSCl3. The complexes containing nBu-substituted ligands have been used as single source precursors for low pressure chemical vapour deposition (CVD) of 3R-NbS2 thin films. 2H-NbSe2 thin films were also obtained via low pressure CVD using [NbSe2Cl3(SenBu2)]. The thin films were characterised by grazing incidence and in-plane XRD, pole figure analysis, scanning electron microscopy and energy dispersive X-ray analysis.

  19. Comparison of ambulatory blood pressure measurement with home, office and pharmacy measurements: is arterial blood pressure measured at pharmacy reliable? (United States)

    Mutlu, Sinan; Sari, Oktay; Arslan, Erol; Aydogan, Umit; Doganer, Yusuf C; Koc, Bayram


    Standardizing arterial blood pressure (BP) measurement is difficult because of different performers like doctor or pharmacy employee. We investigated the reliability between different BP measurement methods. The study was conducted in an internal medicine service with 160 patients in Ankara, Turkey. First, the subjects' BP was measured by doctor. Then, 24-hour BP monitoring devices were placed. Participants were then instructed to measure their BPs both at home and in pharmacy. The next day, arterial BP was measured by the doctor for the second time. The prevalence rates of masked and white coat hypertension were 8.8% (n = 14) and 8.1% (n = 13), respectively. There was no statistically significant differences between ambulatory measurement and home, office and pharmacy measurements (P > 0.05). The consistency rate between ambulatory and home measurements was 97.5% (kappa = 0.947, P home measurement. There was a moderate positive correlation between ambulatory and other measurements in both systolic and diastolic values. There was a positive and very strong correlation between ambulatory and home measurements of systolic and diastolic ABP values (respectively; r = 0.926 and r = 0.968) and there was a statistically significant relation between these measurements (P home measurement when compared with ambulatory measurement. But both office and pharmacy measurements had also high sensitivity and specificity. © 2015 John Wiley & Sons, Ltd.

  20. Measurement of earthworm radial pressures during peristaltic motion (United States)

    Ruiz, Siul; Or, Dani


    Earthworm activity and formation of burrowing networks are important for soil structure formation and transport processes. We developed models for earthworm penetration cavity expansion that consider soil hydration and mechanical status. A key parameter is the maxima axial and radial pressure exerted by the earthworm hydroskeleton (presently estimated at 200 kPa). To test a range of pressures exerted by moving earthworms we developed a coaxial chamber consisting of Plexiglas tube fitted with a thin and inflatable silicon tubing that hosts the earthworm. We pressurize the gap between the Plexiglas and flexible tubing using an incompressible liquid linked to a pressure transducer. Earthworm motion and concurrent pressure were recorded by the transducer and a dedicated video camera. The instrument was calibrated using a cardiac catheter resulting in close agreement between the catheter and chamber pressures. Measurements using anecic earthworms passing across the cylinder show mean radial pressures of 70 kPa, consistent with earlier findings of anecic earthworm pressure measurements using different measurement techniques. Analyses are underway to resolve local pressures induced during peristaltic motion. The study delineates mechanical constraints to soil bioturbation by earthworms for different mechanical conditions including compaction. Tests are underway for direct measurement of plant root pressures during growth.

  1. Modern gas-based temperature and pressure measurements

    CERN Document Server

    Pavese, Franco


    This 2nd edition volume of Modern Gas-Based Temperature and Pressure Measurements follows the first publication in 1992. It collects a much larger set of information, reference data, and bibliography in temperature and pressure metrology of gaseous substances, including the physical-chemical issues related to gaseous substances. The book provides solutions to practical applications where gases are used in different thermodynamic conditions. Modern Gas-Based Temperature and Pressure Measurements, 2nd edition is the only comprehensive survey of methods for pressure measurement in gaseous media used in the medium-to-low pressure range closely connected with thermometry. It assembles current information on thermometry and manometry that involve the use of gaseous substances which are likely to be valid methods for the future. As such, it is an important resource for the researcher. This edition is updated through the very latest scientific and technical developments of gas-based temperature and pressure measurem...

  2. Velocity-pressure correlation measurements in complex free shear flows

    Energy Technology Data Exchange (ETDEWEB)

    Naka, Yoshitsugu [Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi Kohoku-ku, Yokohama-city 223-8522 (Japan)], E-mail:; Obi, Shinnosuke [Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi Kohoku-ku, Yokohama-city 223-8522 (Japan)], E-mail:


    Simultaneous measurements of fluctuating velocity and pressure were performed in various turbulent free shear flows including a turbulent mixing layer and the wing-tip vortex trailing from a NACA0012 half-wing. Two different methods for fluctuating static pressure measurement were considered: a direct method using a miniature Pitot tube and an indirect method where static pressure was calculated from total pressure. The pressure obtained by either of these methods was correlated with the velocity measured by an X-type hot-wire probe. The results from these two techniques agreed with each other in the turbulent mixing layer. In the wing-tip vortex case, however, some discrepancies were found, although overall characteristics of the pressure-related statistics were adequately captured by both methods.

  3. Preliminary Photon Pressure Measurements Using a Solar Simulator (United States)

    Gray, Perry A.; Edwards, David L.; Carruth, M. Ralph, Jr.; Carruth, M. Ralph, Jr. (Technical Monitor)


    Initial proof of concept photon momentum measurements reported verifying photon pressure on a simulated sail material can be measured under high vacuum conditions using a full spectrum solar simulator and a vacuum compatible force measurement system. Second order effects such as sample reflectivity, beam uniformity, radiometric flux measurement accuracy, and the optical system have been accounted for in evaluating these measurements.

  4. New technologies for measuring intraocular pressure. (United States)

    Garcia-Feijoo, Julian; Martinez-de-la-Casa, Jose María; Morales-Fernandez, Laura; Saenz Frances, Federico; Santos-Bueso, Enrique; Garcia-Saenz, Sofia; Mendez-Hernandez, Carmen


    The level of intraocular pressure (IOP) is the main known risk factor for the development and progression of glaucomatous optic neuropathy. Despite Goldmann applanation tonometry (GAT) being the gold standard for determining IOP since the last century, its limitations were obvious from the start and include substantial effects of several eye variables such as axial length, curvature, rigidity, and corneal thickness. These limitations have prompted the development of numerous formulas and nomograms designed to compensate for the ocular characteristics effect on GAT, but none of these methods has been entirely satisfactory. Similarly, as a result of efforts to mitigate some of the limitations of conventional tonometry, several new tonometers have appeared on the scene. © 2015 Elsevier B.V. All rights reserved.

  5. Measuring blood pressure in mice using volume pressure recording, a tail-cuff method. (United States)

    Daugherty, Alan; Rateri, Debra; Hong, Lu; Balakrishnan, Anju


    The CODA 8-Channel High Throughput Non-Invasive Blood Pressure system measures the blood pressure in up to 8 mice or rats simultaneously. The CODA tail-cuff system uses Volume Pressure Recording (VPR) to measure the blood pressure by determining the tail blood volume. A specially designed differential pressure transducer and an occlusion tail-cuff measure the total blood volume in the tail without the need to obtain the individual pulse signal. Special attention is afforded to the length of the occlusion cuff in order to derive the most accurate blood pressure readings. VPR can easily obtain readings on dark-skinned rodents, such as C57BL6 mice and is MRI compatible. The CODA system provides you with measurements of six (6) different blood pressure parameters; systolic and diastolic blood pressure, heart rate, mean blood pressure, tail blood flow, and tail blood volume. Measurements can be made on either awake or anesthetized mice or rats. The CODA system includes a controller, laptop computer, software, cuffs, animal holders, infrared warming pads, and an infrared thermometer. There are seven different holder sizes for mice as small as 8 grams to rats as large as 900 grams.

  6. Monitoring Personalized Trait Using Oscillometric Arterial Blood Pressure Measurements

    Directory of Open Access Journals (Sweden)

    Young-Suk Shin


    Full Text Available The blood pressure patterns obtained from a linearly or stepwise deflating cuff exhibit personalized traits, such as fairly uniform peak patterns and regular beat geometry; it can support the diagnosis and monitoring of hypertensive patients with reduced sensitivity to fluctuations in Blood Pressure (BP over time. Monitoring of personalized trait in Oscillometric Arterial Blood Pressure Measurements (OABPM uses the Linear Discriminant Analysis (LDA algorithm. The representation of personalized traits with features from the oscillometric waveforms using LDA algorithm includes four phases. Data collection consists of blood pressure data using auscultatory measurements and pressure oscillations data obtained from the oscillometric method. Preprocessing involves the normalization of various sized oscillometric waveforms to a uniform size. Feature extraction involves the use of features from oscillometric amplitudes, and trait identification involves the use of the LDA algorithm. In this paper, it presents a novel OABPM-based blood pressure monitoring system that can monitor personalized blood pressure pattern. Our approach can reduce sensitivity to fluctuations in blood pressure with the features extracted from the whole area in oscillometric arterial blood pressure measurement. Therefore this technique offers reliable blood pressure patterns. This study provides a cornerstone for the diagnosis and management of hypertension in the foreseeable future.

  7. Auscultatory versus oscillometric measurement of blood pressure in octogenarians. (United States)

    Rosholm, Jens-Ulrik; Arnspang, Sidsel; Matzen, Lars; Jacobsen, Ib A


    Auscultatory measurement using a sphygmomanometer has been the predominant method for clinical estimation of blood pressure, but it is now rapidly being replaced by oscillometric measurement. To compare blood pressure by auscultatory and oscillometric measurements in patients ≥ 80 years. 100 patients had blood pressure measured by auscultation with a sphygmomanometer and by an electronic device using the oscillometric method. For each patient the mean of two blood pressures with each method measured within 15 min were compared. The mean age of participants was 85.8 years; 55.8% were women. The correlation coefficient for systolic blood pressure was 0.88 and for diastolic 0.79. Differences between auscultatory and oscillometric values were less than 10 mmHg in 70.6% of systolic blood pressures and in 83.2% for diastolic. Arrhythmia and hypertension did not influence the results, and there was no correlation between the magnitude of the differences and the level of blood pressure. Agreement between oscillometric and auscultatory measurements of blood pressure in octogenarians was found to be less than required by validation protocols. However, semi-automatic equipment, which is observer-independent, may be used even in the very elderly, particularly if multiple readings are performed.

  8. Blood pressure self-measurement in the obstetric waiting room

    DEFF Research Database (Denmark)

    Wagner, Stefan; Kamper, Christina H.; Toftegaard, Thomas Skjødeberg


    Background: Pregnant diabetic patients are often required to self- measure their blood pressure in the waiting room before consulta- tion. Currently used blood pressure devices do not guarantee valid measurements when used unsupervised. This could lead to misdi- agnosis and treatment error. The aim...... of this study was to investigate current use of blood pressure self-measurement in the waiting room in order to identify challenges that could influence the resulting data quality. Also, we wanted to investigate the potential for addressing these challenges with e-health and telemedicine technology. Subjects...... a reliable blood pressure reading. Results: We found that the patients did not adhere to given instructions when performing blood pressure self-measurement in the waiting room. None of the 81 patients adhered to all six inves- tigated recommendations, while around a quarter adhered to five out of six...

  9. The effect of clothes on blood pressure measurement (United States)

    Ertug, Nurcan; Cakal, Tugba; Ozturk, Seyda Busra; Verim, Muhammet


    Objective: To determine the effect of clothes on blood pressure measurement. Methods: One group pretest-posttest design was used in this study. The study consisted of 162 undergraduate students studying nursing and physiotherapy at a university in Ankara, Turkey. Blood pressure was measured over the sleeve and below a rolled-up sleeve with a mercury-filled column sphygmomanometer. All blood pressure measurements were performed on the right arm during morning hours by the same nurse. Each participant’s height, weight and clothing thickness were measured. Results: The mean age of the participants was 20.71. The median systolic blood pressure values were 110.07 mmHg over the sleeve and 110.37 mmHg below the rolled-up sleeve. There were no statistically significant differences between measurements taken over the sleeve and below a rolled-up sleeve (p=0.222). The median diastolic blood pressure values were 69.56 mmHg over the sleeve and 69.59 mmHg below the rolled-up sleeve. There were no statistically significant differences between measurements taken over the sleeve and below a rolled-up sleeve (p=0.572). Conclusion: It was found that clothes have no statistically significant effect on systolic/diastolic blood pressure measurements. Measuring blood pressure over a sleeve may save time. PMID:28367201

  10. (Vapour + liquid) equilibria of (fluoromethane + tetrafluoromethane) at the temperature 130.46 K


    Fonseca, I. M. A.; Sardinha, G. G.; Lobo, Lélio Q.


    The total vapour pressure of binary liquid mixtures of (fluoromethane+tetrafluoromethane) has been measured at the temperature 130.46 K. Two partially miscible liquid phases were found. The excess molar Gibbs energy was calculated in the region where the two liquids are mutually soluble. For the hypothetical equimolar mixture,GEm01 (x=0.5)=846 Jmol-1.

  11. Monitoring Personalized Trait Using Oscillometric Arterial Blood Pressure Measurements


    Young-Suk Shin


    The blood pressure patterns obtained from a linearly or stepwise deflating cuff exhibit personalized traits, such as fairly uniform peak patterns and regular beat geometry; it can support the diagnosis and monitoring of hypertensive patients with reduced sensitivity to fluctuations in Blood Pressure (BP) over time. Monitoring of personalized trait in Oscillometric Arterial Blood Pressure Measurements (OABPM) uses the Linear Discriminant Analysis (LDA) algorithm. The representation of personal...

  12. Differential intracochlear sound pressure measurements in normal human temporal bones. (United States)

    Nakajima, Hideko Heidi; Dong, Wei; Olson, Elizabeth S; Merchant, Saumil N; Ravicz, Michael E; Rosowski, John J


    We present the first simultaneous sound pressure measurements in scala vestibuli and scala tympani of the cochlea in human cadaveric temporal bones. The technique we employ, which exploits microscale fiberoptic pressure sensors, enables the study of differential sound pressure at the cochlear base. This differential pressure is the input to the cochlear partition, driving cochlear waves and auditory transduction. In our results, the sound pressure in scala vestibuli (P (SV)) was much greater than scala tympani pressure (P (ST)), except for very low and high frequencies where P (ST) significantly affected the input to the cochlea. The differential pressure (P (SV) - P (ST)) is a superior measure of ossicular transduction of sound compared to P (SV) alone: (P (SV)-P (ST)) was reduced by 30 to 50 dB when the ossicular chain was disarticulated, whereas P (SV) was not reduced as much. The middle ear gain P (SV)/P (EC) and the differential pressure normalized to ear canal pressure (P (SV) - P (ST))/P (EC) were generally bandpass in frequency dependence. At frequencies above 1 kHz, the group delay in the middle ear gain is about 83 micros, over twice that of the gerbil. Concurrent measurements of stapes velocity produced estimates of cochlear input impedance, the differential impedance across the partition, and round window impedance. The differential impedance was generally resistive, while the round window impedance was consistent with compliance in conjunction with distributed inertia and damping. Our technique of measuring differential pressure can be used to study inner ear conductive pathologies (e.g., semicircular dehiscence), as well as non-ossicular cochlear stimulation (e.g., round window stimulation and bone conduction)--situations that cannot be completely quantified by measurements of stapes velocity or scala vestibuli pressure by themselves.


    DEFF Research Database (Denmark)

    Hoffmann-Petersen, N; Lauritzen, T; Bech, J N


    of the measurements and subsequent communication by telephone or E-mail. In the control group, patients received usual care. Primary outcome was reduction in daytime ambulatory blood pressure measurements (ABPM) from baseline to 3 months' follow-up. RESULTS: In both groups, daytime ABPM decreased significantly......OBJECTIVE: Telemonitoring of home blood pressure measurements (TBPM) is a new and promising supplement to diagnosis, control and treatment of hypertension. We wanted to compare the outcome of antihypertensive treatment based on TBPM and conventional monitoring of blood pressure. DESIGN AND METHOD....../181), p = 0.34. Blood pressure reduction in the TBPM group varied with the different practices. CONCLUSIONS: No further reduction in ABPM or number of patients reaching blood pressure targets was observed when electronic transmission of TBPM was applied in the treatment of hypertension by GPs. Thus...

  14. A note on measurement of sound pressure with intensity probes

    DEFF Research Database (Denmark)

    Juhl, Peter; Jacobsen, Finn


    be improved under a variety of realistic sound field conditions by applying a different weighting of the two pressure signals from the probe. The improved intensity probe can measure the sound pressure more accurately at high frequencies than an ordinary sound intensity probe or an ordinary sound level meter......The effect of scattering and diffraction on measurement of sound pressure with "two-microphone" sound intensity probes is examined using an axisymmetric boundary element model of the probe. Whereas it has been shown a few years ago that the sound intensity estimated with a two-microphone probe...... is reliable up to 10 kHz when using 0.5 in. microphones in the usual face-to-face arrangement separated by a 12 mm spacer, the sound pressure measured with the same instrument will typically be underestimated at high frequencies. It is shown in this paper that the estimate of the sound pressure can...

  15. Blood pressure measurement in adults: large cuffs for all?


    Croft, P R; Cruickshank, J K


    STUDY OBJECTIVE--The aim of the study was to determine whether a single size of cuff for adult blood pressure measurements is appropriate for general clinical practice. DESIGN--The study was a prospective survey of a sample of adult blood pressure measurements using two cuffs with different bladder sizes (12 X 23 cm and 15 X 33 cm) in a randomised design using a random zero sphygmomanometer. SETTING--Blood pressures were measured in a general practice and in a hospital outpatient clinic. PART...

  16. Salt pressure derived from GMS-B1 measurements

    Energy Technology Data Exchange (ETDEWEB)

    Vonka, V.


    The GMS system is successfully used to measure gaps between the liner tube and the disc in the B1 hole. GMS was designed for evaluation of minimum tube diameter. In this report measured results are used to estimate the tube compression. The compression is recalculated into the salt pressure acting on the liner tube from outside. It is concluded that the GMS measurements are accurately executed. Also the evaluation procedure to eliminate the thermal expansion effect is correctly applied. Through the B1 liner tube compression the salt pressure on the tube is evaluated. Apart from several thermocouples no other measuring instrument has been used. The resulting salt pressure estimate is consequently considered as independent of other HAW salt pressure measurements. (author). 6 refs., 10 figs., 2 tabs.

  17. Pico gauges for minimally invasive intracellular hydrostatic pressure measurements. (United States)

    Knoblauch, Jan; Mullendore, Daniel L; Jensen, Kaare H; Knoblauch, Michael


    Intracellular pressure has a multitude of functions in cells surrounded by a cell wall or similar matrix in all kingdoms of life. The functions include cell growth, nastic movements, and penetration of tissue by parasites. The precise measurement of intracellular pressure in the majority of cells, however, remains difficult or impossible due to their small size and/or sensitivity to manipulation. Here, we report on a method that allows precise measurements in basically any cell type over all ranges of pressure. It is based on the compression of nanoliter and picoliter volumes of oil entrapped in the tip of microcapillaries, which we call pico gauges. The production of pico gauges can be accomplished with standard laboratory equipment, and measurements are comparably easy to conduct. Example pressure measurements are performed on cells that are difficult or impossible to measure with other methods. © 2014 American Society of Plant Biologists. All Rights Reserved.

  18. Pico gauges for minimally invasive intracellular hydrostatic pressure measurements

    DEFF Research Database (Denmark)

    Knoblauch, Jan; Mullendore, Daniel L.; Jensen, Kaare Hartvig


    in the tip of microcapillaries, which we call pico gauges. The production of pico gauges can be accomplished with standard laboratory equipment, and measurements are comparably easy to conduct. Example pressure measurements are performed on cells that are difficult or impossible to measure with other methods.......Intracellular pressure has a multitude of functions in cells surrounded by a cell wall or similar matrix in all kingdoms of life. The functions include cell growth, nastic movements, and penetration of tissue by parasites. The precise measurement of intracellular pressure in the majority of cells......, however, remains difficult or impossible due to their small size and/or sensitivity to manipulation. Here, we report on a method that allows precise measurements in basically any cell type over all ranges of pressure. It is based on the compression of nanoliter and picoliter volumes of oil entrapped...

  19. Perilymphatic pressure measurement in patients with Meniere's disease

    NARCIS (Netherlands)

    Mateijsen, DJM; Rosingh, HJ; Wit, HP; Albers, FWJ

    The MMS-10 Tympanic Displacement Analyser is a new device for measuring perilymphatic pressure in humans. This instrument was used in 70 patients with Meniere's disease (44 affected ears) and a group of 50 young normal hearing subjects. No significant differences in perilymphatic pressure

  20. Definition-consistent measurement of exchange market pressure

    NARCIS (Netherlands)

    Klaassen, F.; Jager, H.


    Currencies can be under severe pressure, but in a managed exchange rate regime that is not fully visible via the change in the exchange rate. The literature has proposed a way to measure such exchange market pressure (EMP) indirectly, by adding interest rate changes and forex interventions to the

  1. Measuring static seated pressure distributions and risk for skin pressure ulceration in ice sledge hockey players. (United States)

    Darrah, Shaun D; Dicianno, Brad E; Berthold, Justin; McCoy, Andrew; Haas, Matthew; Cooper, Rory A


    To determine whether sledge hockey players with physical disability have higher average seated pressures compared to non-disabled controls. Fifteen age-matched controls without physical disability and 15 experimental participants with physical disability were studied using a pressure mapping device to determine risk for skin pressure ulceration and the impact of cushioning and knee angle positioning on seated pressure distributions. Regardless of participant group, cushioning, or knee angle, average seated pressures exceeded clinically acceptable seated pressures. Controls had significantly higher average seated pressures than the disability group when knees were flexed, both with the cushion (p = 0.013) and without (p = 0.015). Knee extension showed significantly lower average pressures in controls, both with the cushion (p hockey players utilize positioning with larger knee flexion angles. Implications for Rehabilitation Ice sledge hockey is a fast growing adaptive sport. Adaptive sports have been associated with several positive improvements in overall health and quality of life, though may be putting players at risk for skin ulceration. Measured static seated pressure in sledges greatly exceeds current clinically accepted clinical guidelines. With modern improvements in wheelchair pressure relief/cushioning there are potential methods for improvement of elevated seated pressure in ice hockey sledges.

  2. Development of a Blood Pressure Measurement Instrument with Active Cuff Pressure Control Schemes

    Directory of Open Access Journals (Sweden)

    Chung-Hsien Kuo


    Full Text Available This paper presents an oscillometric blood pressure (BP measurement approach based on the active control schemes of cuff pressure. Compared with conventional electronic BP instruments, the novelty of the proposed BP measurement approach is to utilize a variable volume chamber which actively and stably alters the cuff pressure during inflating or deflating cycles. The variable volume chamber is operated with a closed-loop pressure control scheme, and it is activated by controlling the piston position of a single-acting cylinder driven by a screw motor. Therefore, the variable volume chamber could significantly eliminate the air turbulence disturbance during the air injection stage when compared to an air pump mechanism. Furthermore, the proposed active BP measurement approach is capable of measuring BP characteristics, including systolic blood pressure (SBP and diastolic blood pressure (DBP, during the inflating cycle. Two modes of air injection measurement (AIM and accurate dual-way measurement (ADM were proposed. According to the healthy subject experiment results, AIM reduced 34.21% and ADM reduced 15.78% of the measurement time when compared to a commercial BP monitor. Furthermore, the ADM performed much consistently (i.e., less standard deviation in the measurements when compared to a commercial BP monitor.

  3. Measurement of partial pressures in vacuum technology and vacuum physics (United States)

    Huber, W. K.


    It is pointed out that the measurement of gaseous pressures of less than 0.0001 torr is based on the ionization of gas atoms and molecules due to collisions with electrons. The particle density is determined in place of the pressure. The ionization cross sections for molecules of various gases are discussed. It is found that the true pressure in a vacuum system cannot be determined with certainty if it is unknown which gas is present. Effects of partial pressure determination on the condition of the vacuum system are discussed together with ion sources, systems of separation, and ion detection.

  4. A technique to measure eyelid pressure using piezoresistive sensors. (United States)

    Shaw, Alyra J; Davis, Brett A; Collins, Michael J; Carney, Leo G


    In this paper, novel procedures were developed using a thin (0.17 mm) tactile piezoresistive pressure sensor mounted on a rigid contact lens to measure upper eyelid pressure. A hydrostatic calibration system was constructed, and the influence of conditioning (prestressing), drift (continued increasing response with a static load), and temperature variations on the response of the sensor were examined. To optimally position the sensor-contact lens combination under the upper eyelid margin, an in vivo measurement apparatus was constructed. Calibration gave a linear relationship between raw sensor output and actual pressure units for loads between 1 and 10 mmHg ( R(2) = 0.96 ). Conditioning the sensor prior to use regulated the measurement response, and sensor output stabilized about 10 s after loading. While sensor output drifts slightly over several hours, it was not significant beyond the measurement time of 1 min used for eyelid pressure. The error associated with calibrating at room temperature but measuring at ocular surface temperature led to a very small overestimation of pressure. Eyelid pressure readings were observed when the upper eyelid was placed on the sensor, and removed during a recording. When the eyelid pressure was increased by pulling the lids tighter against the eye, the readings from the sensor significantly increased.

  5. Intercomparison of TCCON and MUSICA Water Vapour Products (United States)

    Weaver, D.; Strong, K.; Deutscher, N. M.; Schneider, M.; Blumenstock, T.; Robinson, J.; Notholt, J.; Sherlock, V.; Griffith, D. W. T.; Barthlott, S.; García, O. E.; Smale, D.; Palm, M.; Jones, N. B.; Hase, F.; Kivi, R.; Ramos, Y. G.; Yoshimura, K.; Sepúlveda, E.; Gómez-Peláez, Á. J.; Gisi, M.; Kohlhepp, R.; Warneke, T.; Dohe, S.; Wiegele, A.; Christner, E.; Lejeune, B.; Demoulin, P.


    We present an intercomparison between the water vapour products from the Total Carbon Column Observing Network (TCCON) and the MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water (MUSICA), two datasets from ground-based Fourier Transform InfraRed (FTIR) spectrometers with good global representation. Where possible, comparisons to radiosondes are also included. The near-infrared TCCON measurements are optimized to provide precise monitoring of greenhouse gases for carbon cycle studies; however, TCCON's retrievals also produce water vapour products. The mid-infrared MUSICA products result from retrievals optimized to give precise and accurate information about H2O, HDO, and δD. The MUSICA water vapour products have been validated by extensive intercomparisons with H2O and δD in-situ measurements made from ground, radiosonde, and aircraft (Schneider et al. 2012, 2014), as well as by intercomparisons with satellite-based H2O and δD remote sensing measurements (Wiegele et al., 2014). This dataset provides a valuable reference point for other measurements of water vapour. This study is motivated by the limited intercomparisons performed for TCCON water vapour products and limited characterisation of their uncertainties. We compare MUSICA and TCCON products to assess the potential for TCCON measurements to contribute to studies of the water cycle, water vapour's role in climate and use as a tracer for atmospheric dynamics, and to evaluate the performance of climate models. The TCCON and MUSICA products result from measurements taken using the same FTIR instruments, enabling a comparison with constant instrumentation. The retrieval techniques differ, however, in their method and a priori information. We assess the impact of these differences and characterize the comparability of the TCCON and MUSICA datasets.

  6. Automated analysis of blood pressure measurements (Korotkov sound) (United States)

    Golden, D. P.; Hoffler, G. W.; Wolthuis, R. A.


    Automatic system for noninvasive measurements of arterial blood pressure is described. System uses Korotkov sound processor logic ratios to identify Korotkov sounds. Schematic diagram of system is provided to show components and method of operation.

  7. System for measuring multiphase flow using multiple pressure differentials (United States)

    Fincke, James R.


    An improved method and system for measuring a multi-phase flow in a pressure flow meter. An extended throat venturi is used and pressure of the multi-phase flow is measured at three or more positions in the venturi, which define two or more pressure differentials in the flow conduit. The differential pressures are then used to calculate the mass flow of the gas phase, the total mass flow, and the liquid phase. The system for determining the mass flow of the high void fraction fluid flow and the gas flow includes taking into account a pressure drop experienced by the gas phase due to work performed by the gas phase in accelerating the liquid phase.

  8. Pressure-Sensitive Paint Measurement Technique Development for Turbomachinery Application (United States)


    maximum 200 words ) Pressure- sensitive paint measurement on a transonic compressor rotor required the prior development of phase-locked cumulative...reported. 14. SUBJECT TERMS Pressure- Sensitive Paint, Phase-Locked Imaging , Transonic Rotor Measurements, CFD Analysis 15. NUMBER OF PAGES 98 16... image was saved in a .TIFF picture format in the hard drive memory of the PC under directory C:/4MIP/ IMAGES /. The turbine was then shut down and

  9. Blood pressure measurement for hypertension in pregnancy. (United States)

    Dehaeck, Ulrike; Thurston, Jackie; Gibson, Paul; Stephanson, Kirk; Ross, Sue


    Ambulatory BP monitoring (ABPM) has been proposed as a logical approach to overcoming many of the problems associated with clinical BP measurement. The extent of its use in diagnosing hypertension in pregnancy is unknown. The objective of this study was to identify the practices surrounding use of ABPM by practitioners to diagnose hypertension (HTN) and white coat hypertension (WCH) in pregnant women. We mailed questionnaires to all obstetricians and family doctors practising obstetrics who were listed in the online medical directory of the College of Physicians and Surgeons of Alberta. Data were analyzed using SPSS. Completed questionnaires were received from 81 obstetricians and 86 primary care physicians who manage hypertension in pregnancy. The majority of obstetricians (83%) and primary care physicians (79%) indicated that they "almost always" or "often" attempt to differentiate WCH from true HTN in pregnancy. The most popular method identified to differentiate WCH from true HTN in pregnancy was self (intermittent) home BP monitoring (78% of obstetricians and 69% of primary care physicians, P = 0.18). A minority of physicians in each group reported using ABPM to evaluate HTN in pregnancy, with significantly fewer obstetricians using ABPM diagnostically than primary care physicians (12% vs. 26%, P = 0.04). Obstetrical care providers in Alberta are aware that WCH is an issue among pregnant women. While ABPM is chosen in a minority of cases, both obstetricians and primary care physicians appear to have a strong preference to use self BP monitoring for further BP evaluation.

  10. Pressure and Relative Humidity Measurement Devices for Mars 2020 Rover (United States)

    Hieta, M.; Genzer, M.; Nikkanen, T.; Haukka, H.; Harri, A.-M.; Polkko, J.; Rodriguez-Manfredi, J. A.


    One of the scientific payloads onboard the NASA Mars 2020 rover mission is Mars Environmental Dynamic Analyzer (MEDA): a set of environmental sensors for Mars surface weather measurements. Finnish Meteorological Institute (FMI) provides a pressure measurement device (MEDA PS) and a relative humidity measurement device (MEDA HS) for MEDA.

  11. Compression-tracking photoacoustic perfusion and microvascular pressure measurements (United States)

    Choi, Min; Zemp, Roger


    We propose a method to measure blood pressure of small vessels non-invasively and in-vivo: by combining PA imaging with compression US. Using this method, we have shown pressure-lumen area tracking, as well as estimation of the internal vessel pressure, located 2 mm deep in tissue. Additionally, reperfusion can be tracked by measuring the total PA signal within a region of interest (ROI) after compression has been released. The ROI is updated using cross-correlation based displacement tracking1. The change in subcutaneous perfusion rates can be seen when the temperature of the hand of a human subject drops below the normal.

  12. Parametric Reconstruction of Water Vapour Accumulation Modes in the Western and the Eastern Mediterranean Basins (United States)

    Palau, J. L.; Rovira, F.; Millan, M.


    The Mediterranean Sea acts as a source of heat and moisture for the surrounding regions, but not only because it is a closed and warm sea. The Mediterranean Basin is located in the mid-latitudes (i.e., high solar insolation), and it is almost completely surrounded by mountains. Moreover, from a meteorological point of view, the Mediterranean Basin can be regarded as two well-differentiated sub-basins: The Western Mediterranean Basin, where the prevailing synoptic conditions are associated with the Azores High Pressure system; and the Eastern Mediterranean Basin, which is under the influence of the Middle-East monsoon low-pressure system. The combination of all these features enables strong evapotranspiration with lower ventilation conditions (especially on the Western side) than in other geographical areas of the world (e.g., areas under the direct influence of the Atlantic Ocean). As a result, there are different water vapour "accumulation modes” on both sides of the Mediterranean Basin. The determination of the main atmospheric accumulation modes and their seasonal variability on both sides of the Mediterranean Basin is a relevant issue for integrating some of the feedbacks driving climate change, e.g., precipitation regimes, secondary pollutant production, ventilation conditions, etc. This study focuses on the total water vapour accumulation modes found on both sides of the Mediterranean Basin throughout the year. The data used in this study come from the most recent EOS satellite missions. Specifically, this investigation analyses the nine-year time series of water vapour data measured by the MODIS instrument (MODerate Resolution Imaging Spectroradiometer) on board the TERRA (EOS AM-1) satellite. Annual evolution (2000-2008) and seasonality of the total precipitable water column are analysed in both the Western and the Eastern Mediterranean Basins. After carrying out the parametric reconstruction of the water vapour time series, we have obtained their

  13. Use of an Ethanol-Driven Pressure Cell to Measure Hydrostatic Pressure Response of Protein-Stabilized Gold Nanoclusters (United States)


    ARL-TR-7577 ● JAN 2016 US Army Research Laboratory Use of an Ethanol -Driven Pressure Cell to Measure Hydrostatic Pressure...ARL-TR-7577 ● JAN 2016 US Army Research Laboratory Use of an Ethanol -Driven Pressure Cell to Measure Hydrostatic Pressure Response of...DATES COVERED (From - To) May 2014–September 2014 4. TITLE AND SUBTITLE Use of an Ethanol -Driven Pressure Cell to Measure Hydrostatic Pressure

  14. Mixing of multiple metal vapours into an arc plasma in gas tungsten arc welding of stainless steel (United States)

    Park, Hunkwan; Trautmann, Marcus; Tanaka, Keigo; Tanaka, Manabu; Murphy, Anthony B.


    A computational model of the mixing of multiple metal vapours, formed by vaporization of the surface of an alloy workpiece, into the thermal arc plasma in gas tungsten arc welding (GTAW) is presented. The model incorporates the combined diffusion coefficient method extended to allow treatment of three gases, and is applied to treat the transport of both chromium and iron vapour in the helium arc plasma. In contrast to previous models of GTAW, which predict that metal vapours are swept away to the edge of the arc by the plasma flow, it is found that the metal vapours penetrate strongly into the arc plasma, reaching the cathode region. The predicted results are consistent with published measurements of the intensity of atomic line radiation from the metal vapours. The concentration of chromium vapour is predicted to be higher than that of iron vapour due to its larger vaporization rate. An accumulation of chromium vapour is predicted to occur on the cathode at about 1.5 mm from the cathode tip, in agreement with published measurements. The arc temperature is predicted to be strongly reduced due to the strong radiative emission from the metal vapours. The driving forces causing the diffusion of metal vapours into the helium arc are examined, and it is found that diffusion due to the applied electric field (cataphoresis) is dominant. This is explained in terms of large ionization energies and the small mass of helium compared to those of the metal vapours.

  15. Indirect measurement of arterial blood pressure: physiotherapists’ theoretical knowledge

    Directory of Open Access Journals (Sweden)

    Marcelle Morgana Vieira de Assis


    Full Text Available Blood pressure checking and its theoretical knowledge are crucial to obtain reliable data in clinical examination. Although it is considered a simple technique to be learned and applied, it is not fully dealt with at physiotherapy university courses. Therefore, a wide range of mistakes and misinterpretations are likely to threaten treatment quality. This work aims to evaluate the theory background of physiotherapists for blood pressure measurement. From June to October 2002, 55 physiotherapists answered a 20- question multiple-choice questionnaire on general knowledge related to concepts, anatomy and physiology, suitable equipment, indirect measurement, blood pressure values, mistakes and misinterpretation factors related to blood pressure measurement. The results disclose faulty theory concepts in the sample studied, indicating the need of deeper approach to this complex theme during course and ongoing updating of professionals.

  16. Hepatic venous pressure gradients measured by duplex ultrasound

    Energy Technology Data Exchange (ETDEWEB)

    Tasu, J.-P.; Rocher, L.; Peletier, G.; Kuoch, V.; Kulh, E.; Miquel, A.; Buffet, C.; Biery, M


    AIMS: The hepatic venous pressure gradient is a major prognostic factor in portal hypertension but its measurement is complex and requires invasive angiography. This study investigated the relationship between the hepatic venous pressure gradient and a number of Doppler measurements, including the arterial acceleration index. METHOD: We measured the hepatic venous pressure gradient in 50 fasting patients at hepatic venography. Immediately afterwards, a duplex sonographic examination of the liver was performed at which multiple measurements and indices of the venous and arterial hepatic vasculature were made. RESULTS: Hepatic arterial acceleration was correlated directly with the hepatic venous pressure gradient (r = 0.83, P < 0.0001) and with the Child-Pugh score (r = 0.63, P < 0.0001). An acceleration index cut-off value of 1 m.s{sup -2} provided a positive predictive value of 95%, a sensitivity of 65% and a specificity of 95% for detecting patients with severe portal hypertension (hepatic venous pressure gradient > 12 mmHg). A correlation between the hepatic venous pressure gradient and the congestion index of the portal vein velocity (r = 0.45,P = 0.01) and portal vein velocity (r = 0.40,P = 0.044), was also noted. CONCLUSION: Measuring the hepatic arterial acceleration index may help in the non-invasive evaluation of portal hypertension. Tasu, J.-P. et al. (2002)

  17. Diamond growth by microwave plasma enhanced chemical vapour deposition: Optical emission characterisation and effect argon addition (United States)

    Mortet, V.; Hubicka, Z.; Vorlicek, V.; Jurek, K.; Rosa, J.; Vanecek, M.


    Diamond thin films were grown in an ellipsoidal 6 kWatt microwave plasma chemical vapour deposition reactor [1, 2] in a pressure range of 150 to 250 mbar. Effect of total pressure, methane concentration and argon concentration on diamond growth on mechanically seeded silicon substrates and on plasma characteristics were investigated. Optically good thick diamond films were obtained with high growth rate (4.5 m/h) at high-pressure. The argon concentration affects strongly the deposition rate, the surface morphology and the grain size. The microwave plasma was characterized by optical emission spectroscopy (OES) during deposition. Diamond films were characterized by Raman Spectroscopy and Scanning Electron Microscopy (SEM). The temperatures of the excited CH and C2 species, as well as the excitation temperature were determined from the OES measurements. The plasma composition is sensitive to the methane concentration and especially to the argon concentration in the discharge.

  18. Correction of static pressure on a research aircraft in accelerated flight using differential pressure measurements

    Directory of Open Access Journals (Sweden)

    A. R. Rodi


    Full Text Available A method is described that estimates the error in the static pressure measurement on an aircraft from differential pressure measurements on the hemispherical surface of a Rosemount model 858AJ air velocity probe mounted on a boom ahead of the aircraft. The theoretical predictions for how the pressure should vary over the surface of the hemisphere, involving an unknown sensitivity parameter, leads to a set of equations that can be solved for the unknowns – angle of attack, angle of sideslip, dynamic pressure and the error in static pressure – if the sensitivity factor can be determined. The sensitivity factor was determined on the University of Wyoming King Air research aircraft by comparisons with the error measured with a carefully designed sonde towed on connecting tubing behind the aircraft – a trailing cone – and the result was shown to have a precision of about ±10 Pa over a wide range of conditions, including various altitudes, power settings, and gear and flap extensions. Under accelerated flight conditions, geometric altitude data from a combined Global Navigation Satellite System (GNSS and inertial measurement unit (IMU system are used to estimate acceleration effects on the error, and the algorithm is shown to predict corrections to a precision of better than ±20 Pa under those conditions. Some limiting factors affecting the precision of static pressure measurement on a research aircraft are discussed.

  19. Ethanol vapour sensing properties of screen printed WO3 thick films

    Indian Academy of Sciences (India)

    This paper presents ethanol vapour sensing properties of WO3 thick films. In this work, the WO3 thick films were prepared by standard screen-printing method. These films were characterized by X-ray diffraction (XRD) measurements and scanning electron microscopy (SEM). The ethanol vapour sensing properties of these ...

  20. Comparison of ambulatory blood pressure monitoring and office blood pressure measurements in obese children and adolescents. (United States)

    Renda, Rahime


    Obesity in adults has been related to hypertension and abnormal nocturnal dipping of blood pressure, which are associated with poor cardiovascular and renal outcomes. Here, we aimed to resolve the relationship between the degree of obesity, the severity of hypertension and dipping status on ambulatory blood pressure in obese children. A total 72 patients with primary obesity aged 7 to 18 years (mean: 13.48 ± 3.25) were selected. Patients were divided into three groups based on body mass index (BMİ) Z-score. Diagnosis and staging of ambulatory hypertension based on 24-h blood pressure measurements, obtained from ambulatory blood pressure monitoring. Based on our ambulatory blood pressure data, 35 patients (48.6%) had hypertension, 7 (20%) had ambulatory prehypertension, 21 (60%) had hypertension, and 7 patients (20%) had severe ambulatory hypertension. There was a significant relationship between severity of hypertension and the degree of obesity (p < 0.05). Thirty-one patients (88.6%) had isolated nighttime hypertension, and 53 patients (73.6%) were non-dippers. All systolic blood pressure results and loads were similar between groups. Diastolic and mean arterial blood pressure levels during the night, diastolic blood pressure loads, and heart rate during the day were significantly higher in Group 3 (p < 0.05). Nocturnal non-dipping was not associated with severity of obesity. Obesity was associated with severity of hypertension, higher diastolic blood pressure at night, mean arterial pressure at night, diastolic blood pressure loads and heart rate at day. Increase in BMI Z-score does not a significant impact on daytime blood pressure and nocturnal dipping status.

  1. [Measuring pressure distribution on the human tibia in ski boots]. (United States)

    Schaff, P; Hauser, W


    Pressure distribution inside shoes is of great importance for orthopaedic and biomechanical inquiries. Especially in sports, safety and comfort depend essentially on this quantity, which also determines whether a shoe is well suited for a certain discipline. Therefore, the measurement of pressure distribution allows detailed and objective statements about these factors. Using a set of newly developed thin and highly flexible measuring mats and the corresponding electronic equipment, such statements have become possible. First results with this method were obtained in alpine skiing. 8 different types of ski boots (sizes 5 and 8) worn by 14 subjects were tested on different foreward leans and temperatures using 7-point measuring mats (2 cm2/point) fixed between the boot shaft and the front of the lower leg of each leg. Additional measurements on three different types of boots using a 3 x 24-point mat (1 cm2/point) for the lower leg, as well as measurements underneath the foot with a 14-point (2 cm2/point) and a 80-point (1 cm2/point) mat were performed. A complementary determination of the force at the heel element of a ski binding and a registration of muscular activity (EMG) helped in the interpretation of the results. Some field research using telemetry completed our study. Considerable variations between different boots were found in value and location of pressure maxima. Traditional boots show high pressure values over the instep at foreward leans of 35 degrees and a rise of pressure underneath the forefoot while fixing the buckles, whereas minimal pressure over the instep, no compression of the forefoot and a pressure maximum near the upper end of the shaft are observed in rear entry boots. The force at the heel-important for binding release-varies widely between different boots at the same foreward lean. There was no asymmetry between the pressure distributions of right and left. The pressure distributions for different subjects measured in the same boot were

  2. Validating Center of Pressure Balance Measurements Using the MatScan® Pressure Mat. (United States)

    Goetschius, John; Feger, Mark A; Hertel, Jay; Hart, Joseph M


    Measurements of center of pressure (COP) excursions during balance are common practice in clinical and research settings to evaluate adaptations in postural control due to pathological or environmental conditions. Traditionally measured using laboratory force-plates, pressure-mat devices may be a suitable option for clinicians and scientist to measure COP excursions. Compare COP measures and changes during balance between MatScan® pressure-mat and force-plate. Validation study. Laboratory. Thirty healthy, young adults (19 female,11 male, 22.7±3.4 years, 70.3±SD kg, 1.71±0.09 m). COP excursions were simultaneously measured using pressure-mat and force-plate devices. Participants completed 3 eyes-open and 3 eyes-closed single-leg balance trials (10-seconds). Mean of the 3 trials was used to calculate four COP variables, medial-lateral and anterior-posterior excursion, total distance, and area, with eyes-open and eyes-closed. Percent-change and effect sizes were calculated between eyes-open to closed conditions for each variable and for both devices. All COP variables were highly correlated between devices for eyes-open and eyes-closed conditions (all r > .92, P .85, P 2.25) and similar magnitude between devices. COP measures were correlated between devices, but values tended to be smaller using the pressure-mat. The pressure-mat and force-plate detected comparable magnitude changes in COP measurements between eyes-open and eyes-closed. Pressure-mats may provide be a viable option for detecting large magnitude changes in postural control during short duration testing.

  3. The Use of VMD Data/Model to Test Different Thermodynamic Models for Vapour-Liquid Equilibrium

    DEFF Research Database (Denmark)

    Abildskov, Jens; Azquierdo-Gil, M.A.; Jonsson, Gunnar Eigil


    Vacuum membrane distillation (VMD) has been studied as a separation process to remove volatile organic compounds from aqueous streams. A vapour pressure difference across a microporous hydrophobic membrane is the driving force for the mass transport through the membrane pores (this transport takes...... place in vapour phase). The vapour pressure difference is obtained in VMD processes by applying a vacuum on one side of the membrane. The membrane acts as a mere support for the liquid-vapour equilibrium. The evaporation of the liquid stream takes place on the feed side of the membrane......, and the condensation on the permeate side of the membrane. The paper focus on aroma stripping using VMD; factors influencing flux and separation performance using selected model aroma compounds have been studied. Mainly the following parameters have been examined-aroma compounds: activity coefficient/vapour pressure...

  4. Foldable micro coils for a transponder system measuring intraocular pressure

    Energy Technology Data Exchange (ETDEWEB)

    Ullerich, S.; Schnakenberg, U. [Technische Hochschule Aachen (Germany). Inst. of Materials in Electrical Engineering 1; Mokwa, W. [Technische Hochschule Aachen (Germany). Inst. of Materials in Electrical Engineering 1]|[Fraunhofer Inst. of Microelectronic Circuits and Systems, Duisburg (Germany); Boegel, G. vom [Fraunhofer Inst. of Microelectronic Circuits and Systems, Duisburg (Germany)


    A foldable transponder system consisting of a chip and a micro coil for measuring intraocular pressure continuously is presented. The system will be integrated in the haptic of a soft artificial intraocular lens. Calculations of planar micro coils with 6 mm and 10.3 mm in diameter show the limits for planar coils with an outer diameter of 6 mm. For the realisation of the transponder system a 20 {mu}m thick coil with an outer diameter of 10.3 mm, an inner diameter of 7.7 mm, 16 turns and a gap of 20 {mu}m between the windings was selected. Measurements show a good agreement between calculated and measured values. Wireless pressure measurements were carried out showing a linear behaviour of the output signal with respect to the applied pressure. (orig.)

  5. Invasive v. non-invasive blood pressure measurements the ...

    African Journals Online (AJOL)

    A reasonable correlation exists between invasive and noninvasive methods of measuring systemic blood pressure. However, there are frequent individual differences between these methods and these variations have often caused the validity of the non-invasive measurement to be questioned. The hypothesis that certain ...

  6. Wavenumber-frequency Spectra of Pressure Fluctuations Measured via Fast Response Pressure Sensitive Paint (United States)

    Panda, J.; Roozeboom, N. H.; Ross, J. C.


    The recent advancement in fast-response Pressure-Sensitive Paint (PSP) allows time-resolved measurements of unsteady pressure fluctuations from a dense grid of spatial points on a wind tunnel model. This capability allows for direct calculations of the wavenumber-frequency (k-?) spectrum of pressure fluctuations. Such data, useful for the vibro-acoustics analysis of aerospace vehicles, are difficult to obtain otherwise. For the present work, time histories of pressure fluctuations on a flat plate subjected to vortex shedding from a rectangular bluff-body were measured using PSP. The light intensity levels in the photographic images were then converted to instantaneous pressure histories by applying calibration constants, which were calculated from a few dynamic pressure sensors placed at selective points on the plate. Fourier transform of the time-histories from a large number of spatial points provided k-? spectra for pressure fluctuations. The data provides first glimpse into the possibility of creating detailed forcing functions for vibro-acoustics analysis of aerospace vehicles, albeit for a limited frequency range.

  7. High Pressure Burn Rate Measurements on an Ammonium Perchlorate Propellant

    Energy Technology Data Exchange (ETDEWEB)

    Glascoe, E A; Tan, N


    High pressure deflagration rate measurements of a unique ammonium perchlorate (AP) based propellant are required to design the base burn motor for a Raytheon weapon system. The results of these deflagration rate measurements will be key in assessing safety and performance of the system. In particular, the system may experience transient pressures on the order of 100's of MPa (10's kPSI). Previous studies on similar AP based materials demonstrate that low pressure (e.g. P < 10 MPa or 1500 PSI) burn rates can be quite different than the elevated pressure deflagration rate measurements (see References and HPP results discussed herein), hence elevated pressure measurements are necessary in order understand the deflagration behavior under relevant conditions. Previous work on explosives have shown that at 100's of MPa some explosives will transition from a laminar burn mechanism to a convective burn mechanism in a process termed deconsolidative burning. The resulting burn rates that are orders-of-magnitude faster than the laminar burn rates. Materials that transition to the deconsolidative-convective burn mechanism at elevated pressures have been shown to be considerably more violent in confined heating experiments (i.e. cook-off scenarios). The mechanisms of propellant and explosive deflagration are extremely complex and include both chemical, and mechanical processes, hence predicting the behavior and rate of a novel material or formulation is difficult if not impossible. In this work, the AP/HTPB based material, TAL-1503 (B-2049), was burned in a constant volume apparatus in argon up to 300 MPa (ca. 44 kPSI). The burn rate and pressure were measured in-situ and used to calculate a pressure dependent burn rate. In general, the material appears to burn in a laminar fashion at these elevated pressures. The experiment was reproduced multiple times and the burn rate law using the best data is B = (0.6 {+-} 0.1) x P{sup (1.05{+-}0.02)} where B is the burn

  8. Accuracy of measurement of hand compartment pressures: a cadaveric study. (United States)

    Wong, Justin C; Vosbikian, Michael M; Dwyer, Joseph M; Ilyas, Asif M


    To determine the accuracy of digital palpation for clinical assessment of elevated intracompartmental pressure compared with needle manometry in a simulated compartment syndrome of the hand. Three cadaveric hands were configured with interstitial fluid infusion and an arterial line pressure monitor to create and continuously measure intracompartmental pressure in the thenar and hypothenar compartments. Seventeen assessors clinically judged the presence or absence of compartment syndrome based on digital palpation for firmness and then measured pressures with a handheld manometer. An intracompartmental pressure threshold of 30 mm Hg or greater was used to diagnose compartment syndrome. The sensitivity and specificity of digital palpation of the thenar eminence were 49% and 79%, respectively, with a positive predictive value (PPV) of 86% and negative predictive value (NPV) of 37%. Using the handheld manometer, the sensitivity and specificity increased to 97% and 86% with a PPV of 95% and NPV of 92%. The sensitivity and specificity of digital palpation of the hypothenar eminence were 62% and 83%, respectively, with improvement of 100% and 100%, respectively, with a handheld manometer. For the hypothenar compartment, use of a handheld manometer improved the PPV from 92% to 100% and the NPV from 40% to 100% compared with digital palpation. Digital palpation alone was insufficient to detect elevated compartment pressures in hands at risk for compartment syndrome. Handheld invasive pressure measurement was a useful adjunct for detecting elevated interstitial tissue pressures and may aid in diagnosing compartment syndrome. Diagnostic II. Copyright © 2015 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  9. Automatic blood pressure measurement: the oscillometric waveform shape is a potential contributor to differences between oscillometric and auscultatory pressure measurements. (United States)

    Amoore, John N; Lemesre, Yann; Murray, Ian C; Mieke, Stephan; King, Susan T; Smith, Fiona E; Murray, Alan


    To explore the differences between oscillometric and auscultatory measurements. From a simulator evaluation of a non-invasive blood pressure (NIBP) device regenerating 242 oscillometric blood pressure waveforms from 124 subjects, 10 waveforms were selected based on the differences between the NIBP (oscillometric) and auscultatory pressure measurements. Two waveforms were selected for each of five criteria: systolic over and underestimation; diastolic over and underestimation; and close agreement for both systolic and diastolic pressures. The 10 waveforms were presented to seven different devices and the oscillometric-auscultatory pressure differences were compared between devices and with the oscillometric waveform shapes. Consistent patterns of waveform-dependent over and underestimation of systolic and diastolic pressures were shown for all seven devices. The mean and standard deviation, for all devices, of oscillometric-auscultatory pressure differences were: for the systolic overestimated waveforms, 36 +/- 28/-6 +/- 3 and 23 +/- 2/-1 +/- 3 mmHg (systolic/diastolic differences); for systolic underestimated waveforms, -21 +/- 5/-4 +/- 3 and -11 +/- 4/-3 +/- 3 mmHg; for diastolic overestimated waveforms, 3 +/- 4/12 +/- 5 and 17 +/- 6/10 +/- 2 mmHg; for diastolic underestimated waveforms, 1 +/- 4/-22 +/- 4 and -9 +/- 6/-29 +/- 4 mmHg; and for the two waveforms with good agreement, 0 +/- 6/0 +/- 3 and -2 +/- 4/-4 +/- 3 mmHg. Waveforms for which devices showed good oscillometric and auscultatory agreement had smooth envelopes with clearly defined peaks, compared with the broader plateau and complex shapes of those waveforms for which devices over or underestimated pressures. By increasing the understanding of the characteristics and limitations of the oscillometric method and the effects of waveform shape on pressure measurements, simulator evaluation should lead to improvements in NIBP devices.

  10. Nursing student caring behaviors during blood pressure measurement. (United States)

    Becker, Mary Kay; Blazovich, Linda; Schug, Vicki; Schulenberg, Cathy; Daniels, Jessie; Neal, Diana; Pearson, Gloria; Preston, Sara; Ridgeway, Sharon; Simones, Joyce; Swiggum, Paula; Wenkel, Linda; Smith, MaryJo O


    The purpose of this multisite, nonexperimental study was to examine, using a repeated measures design, the effects of a teaching intervention designed to promote caring behaviors as students learn the psychomotor skill of blood pressure measurement. Watson's theory of human caring and a combination of cognitive and connectionist learning theories were used as the organizing construct. Baccalaureate nursing student participants were videotaped and evaluated at two points in time while performing the psychomotor skill of blood pressure measurement on a role-player. Role-players rated the students' caring behaviors using the Role Player Survey of Caring Behaviors During Blood Pressure Measurement instrument. Between these data collection points, students learned about caring behaviors through analysis of a videotaped role-play and required readings. An evaluator randomly selected 10 student videotapes from each of the 6 baccalaureate nursing program study sites and noted the presence or absence of caring behaviors on the Caring Behaviors During Blood Pressure Measurement instrument. Pretest and posttest scores on both subjective and objective research instruments were compared using descriptive statistics and repeated measures analysis of variance (ANOVA). Students demonstrated a significant improvement in objective and subjective caring behaviors between the two performance examinations. The findings support further investigation of teaching interventions to promote the development of caring behaviors during nursing psychomotor skill development.

  11. Making ET AAS Determination Less Dependent on Vapourization ...

    African Journals Online (AJOL)


    bGerman Aerospace Center, PT-SW, 12489 Berlin, Germany. Received 4 December 2012, revised 5 May 2013, accepted 7 May 2013. ABSTRACT. The quantification of the analytes in ET AAS is normally attained by the measurement and integration of transient absorbance. High degree of atomization and constant vapour ...

  12. Upper tropospheric water vapour variability over tropical latitudes ...

    Indian Academy of Sciences (India)

    Upper tropospheric water vapour variability over tropical latitudes observed using radiosonde and satellite measurements. Ghouse Basha1, M Venkat Ratnam1,∗ and B V Krishna Murthy2. 1National Atmospheric Research Laboratory (NARL), Department of Space, Government of India,. Gadanki, PB No. 123, Tirupati 517 ...

  13. Carbon dioxide and water vapour characteristics on the west coast ...

    Indian Academy of Sciences (India)

    Carbon dioxide and water vapour in the atmo- sphere are considered as the green-house gases and responsible for the global warming, hence much attention has been given to its measurement and analysis (Jones et al. 1978; Jones and Smith 1977;. Leuning et al. 1982; Ohtaki and Matsui 1982;. Ohtaki 1985).

  14. Measurement of digital blood pressure after local cooling

    DEFF Research Database (Denmark)

    Nielsen, S L; Lassen, N A


    A double-inlet plastic cuff was designed for local cooling and systolic blood pressure measurement on the middle phalanx of the fingers. With a tourniquet on the proximal phalanx of one finger, cooling for 5 min made the digital artery temperature equal the skin temperature. The difference between...... the systolic pressure in a control finger and in the cooled finger give the reopening pressure in the digital arteries. At 30, 25, 20, 15, and 10 degrees C, respectively the percent decrease of the finger pressure was 0.2 (0.2), 1.5 (2.5), 8.5 (3.7), 11.4 (3.4), and 15.3 (3.1) in normal young women...

  15. Design Considerations of a Fiber Optic Pressure Sensor Protective Housing for Intramuscular Pressure Measurements. (United States)

    Go, Shanette A; Jensen, Elisabeth R; O'Connor, Shawn M; Evertz, Loribeth Q; Morrow, Duane A; Ward, Samuel R; Lieber, Richard L; Kaufman, Kenton R


    Intramuscular pressure (IMP), defined as skeletal muscle interstitial fluid pressure, reflects changes in individual muscle tension and may provide crucial insight into musculoskeletal biomechanics and pathologies. IMP may be measured using fiber-optic fluid pressure sensors, provided the sensor is adequately anchored to and shielded from surrounding muscle tissue. Ineffective anchoring enables sensor motion and inadequate shielding facilitates direct sensor-tissue interaction, which result in measurement artifacts and force-IMP dissociation. The purpose of this study was to compare the effectiveness of polyimide and nitinol protective housing designs to anchor pressure sensors to muscle tissue, prevent IMP measurement artifacts, and optimize the force-IMP correlation. Anchoring capacity was quantified as force required to dislodge sensors from muscle tissue. Force-IMP correlations and non-physiological measurement artifacts were quantified during isometric muscle activations of the rabbit tibialis anterior. Housing structural integrity was assessed after both anchoring and activation testing. Although there was no statistically significant difference in anchoring capacity, nitinol housings demonstrated greater structural integrity and superior force-IMP correlations. Further design improvements are needed to prevent tissue accumulation in the housing recess associated with artificially high IMP measurements. These findings emphasize fundamental protective housing design elements crucial for achieving reliable IMP measurements.

  16. The characteristics of a vapour bubble moving in a non-uniform flow field (United States)

    Hangen, Ni; Jianbo, Huang


    The present paper describes the dynamic process of a vapour bubble moving in a non-uniform flow field. The coupling between the bubble moving as a whole and the deformation of the bubble surface is considered. The effect of the pressure gradient on the bubble movement is analysed. For a given flow field the numerical calculation is carried out until the vapour bubble is split by a micro-jet.

  17. Measuring Surface Pressure on Rotating Compressor Blades Using Pressure Sensitive Paint

    Directory of Open Access Journals (Sweden)

    Markus Pastuhoff


    Full Text Available 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.

  18. Pressure wire used to measure gradient in chronic mesenteric ischemia. (United States)

    Hannawi, Bashar; Lam, Wilson W; Younis, George Antoine


    Chronic mesenteric ischemia is a rare disorder in the United States. Frequently, its symptoms correlate poorly with the angiographically apparent degree of mesenteric artery stenosis. Measuring the pressure gradient with a small-caliber catheter is an established means of determining whether a particular stenosis is flow-limiting, thus guiding the interventional decision when stenoses are of indeterminate angiographic significance. Using a 0.014-in guidewire, however, is potentially more accurate because it eliminates any measurement error attributable to the use of a larger, potentially obstructive catheter. We present a case of chronic mesenteric ischemia in a 70-year-old woman who had abdominal pain with multiple possible causes. We used a 0.014-in pressure wire to calculate pressure gradients and guide our decision to stent tandem lesions in the superior mesenteric artery. After revascularization, the patient's symptoms improved dramatically. To the best of our knowledge, this is the first published case in which a pressure wire was used to measure a pressure gradient in chronic mesenteric ischemia.

  19. A novel approach to office blood pressure measurement: 30-minute office blood pressure vs daytime ambulatory blood pressure

    NARCIS (Netherlands)

    Wel, M.C. van der; Buunk, I.E.; Weel, C. van; Thien, Th.; Bakx, J.C.


    PURPOSE: Current office blood pressure measurement (OBPM) is often not executed according to guidelines and cannot prevent the white-coat effect. Serial, automated, oscillometric OBPM has the potential to overcome both these problems. We therefore developed a 30-minute OBPM method that we compared

  20. Design optimization and fabrication of a novel structural piezoresistive pressure sensor for micro-pressure measurement (United States)

    Li, Chuang; Cordovilla, Francisco; Ocaña, José L.


    This paper presents a novel structural piezoresistive pressure sensor with a four-beams-bossed-membrane (FBBM) structure that consisted of four short beams and a central mass to measure micro-pressure. The proposed structure can alleviate the contradiction between sensitivity and linearity to realize the micro measurement with high accuracy. In this study, the design, fabrication and test of the sensor are involved. By utilizing the finite element analysis (FEA) to analyze the stress distribution of sensitive elements and subsequently deducing the relationships between structural dimensions and mechanical performance, the optimization process makes the sensor achieve a higher sensitivity and a lower pressure nonlinearity. Based on the deduced equations, a series of optimized FBBM structure dimensions are ultimately determined. The designed sensor is fabricated on a silicon wafer by using traditional MEMS bulk-micromachining and anodic bonding technology. Experimental results show that the sensor achieves the sensitivity of 4.65 mV/V/kPa and pressure nonlinearity of 0.25% FSS in the operating range of 0-5 kPa at room temperature, indicating that this novel structure sensor can be applied in measuring the absolute micro pressure lower than 5 kPa.

  1. Effect of respiration on Korotkoff sounds and oscillometric cuff pressure pulses during blood pressure measurement. (United States)

    Zheng, Dingchang; Di Marco, Luigi Yuri; Murray, Alan


    Blood pressure (BP) measurement accuracy depends on consistent changes in Korotkoff sounds (KorS) for manual measurement and oscillometric pulses for automated measurement, yet little is known about the direct effect of respiration on these physiological signals. The aim of this research was to quantitatively assess the modulation effect of respiration on Korotkoff sounds and oscillometric pulses. Systolic and diastolic blood pressures were measured manually from 30 healthy subjects (age 41 ± 12 years). Three static cuff pressure conditions were studied for two respiratory rates. Cuff pressure [with oscillometric pulses (OscP)], ECG, chest motion respiration [respiration signal (Resp), from magnetometer] and Korotkoff sounds (KorS, from digital stethoscope) were recorded twice for 20 s. The physiological data were evenly resampled. Respiratory frequency was calculated from Resp (fR), OscP (fO) and KorS (fK) from peak spectral frequency. There was no statistically significant difference between fR and fO or fK. Respiratory modulation was observed in all subjects. OscP amplitude modulation changed significantly between the two respiratory rates (p oscillometric pulse and Korotkoff sound amplitudes from which BP is measured.

  2. Office blood pressure measurements with oscillometric devices in adolescents: a comparison with home blood pressure. (United States)

    Jardim, Thiago Veiga; Gaziano, Thomas A; Nascente, Flávia Miquetichuc; Carneiro, Carolina de Souza; Morais, Polyana; Roriz, Vanessa; Mendonça, Karla Lorena; Póvoa, Thaís Inácio Rolim; Barroso, Weimar Kunz Sebba; Sousa, Ana Luiza Lima; Jardim, Paulo César Veiga


    Compare multiple in office BP measurements in adolescents using an oscillometric device with out-of-office blood pressure measurements (home blood pressure monitoring - HBPM). Office measurements were performed with validated semi-automatic devices twice (3 minutes interval) in two different moments (1 week apart), with a total of four readings. These BP readings were named R1, R2, R3 and R4 (following the sequence they were performed), FDM (mean of two readings on first day) and SDM (mean of two readings on second day) and SRM (R2-R4 means). The HBPM protocol included two day-time and two evening-time measurements over 6 days. A total of 1024 students between 12 and 17 years were included (mean age 14.68 years; 52.4% females). The mean systolic blood pressure (SBP) values of R2, SDM and SRM were similar to HBPM values. Regarding diastolic blood pressure (DBP) HBPM value was different than R4. High SBP and DBP correlation coefficients with HBPM values were found for R2, SDM and SRM values. The second office BP measurement performed with an oscilometric device in adolescents was comparable to HBPM values, suggesting that two office readings might be suitable to rule out hypertension in this age group.

  3. Experimental viscosity measurements of biodiesels at high pressure

    Directory of Open Access Journals (Sweden)

    Schaschke C.J.


    Full Text Available The viscosity of biodiesels of soybean and rapeseed biodiesels blended with mineral diesel fuel were measured at pressures of up to 200 MPa. Using a falling sinker-type viscometer reproducible viscosity data were obtained based on the time taken for a sinker to descend a fixed distance down an enclosed tube under the influence of gravity. Measurements were taken using pressures which correspond to those of interest in automotive common rail diesel engines, and at temperatures of between 25ºC and 80ºC. In all cases, the viscosity of the biodiesel blends were found to increase exponentially for which the blends were noted as being more viscous than pure mineral fuels. A pressure-freezing effect was not observed for the blends.

  4. Evaluation of pancreatic tissue fluid pressure measurements intraoperatively and by sonographically guided fine-needle puncture

    DEFF Research Database (Denmark)

    Ebbehøj, N; Borly, L; Bülow, J


    pressure measurements by direct puncture of pancreatic tissue and duct. In patients with chronic pancreatitis we found small week-to-week variations in sonographically guided percutaneous pressure measurements and good agreement between preoperative percutaneous pressure measurements and intraoperative...

  5. Can painted glass felt or glass fibre cloth be used as vapour barrier?

    DEFF Research Database (Denmark)

    El-Khattam, Amira; Andersen, Mie Them; Kielsgaard Hansen, Kurt


    it is essential to know how much influence a surface treatment has on the water vapour transport. Traditionally, there has been most focus on paints that affect the permeability as little as possible. However, sometimes water vapour resistance is desirable. Especially, this is relevant in existing buildings...... on the ceiling e.g. as an ordinary paint. This paper presents the results of an investigation of the water vapour resistance of surface treatments which are commonly used in-door. The water vapour resistance was measured by the cup method. Aerated concrete was investigated with and without various surface...... treatments. The surface treatments were glass felt or glass fibre cloth with different types of paints or just paint. The paint types were acrylic paint and silicate paint. The results show that the paint type has high influence on the water vapour resistance while the underlay i.e. glass felt or glass fibre...

  6. Indications for portal pressure measurement in chronic liver disease

    DEFF Research Database (Denmark)

    Hobolth, Lise; Bendtsen, Flemming; Møller, Søren


    Portal hypertension leads to development of serious complications such as esophageal varices, ascites, renal and cardiovascular dysfunction. The importance of the degree of portal hypertension has been substantiated within recent years. Measurement of the portal pressure is simple and safe and th...

  7. When and how should we measure intra-abdominal pressure ...

    African Journals Online (AJOL)

    A sustained increase in intra-abdominal pressure (IAP) may result in abdominal compartment syndrome (ACS). This is a well documented complication in critically ill patients, but there appears to be a reluctance to routinely measure IAP in patients at high risk of developing intra-abdominal hypertension (IAH) and ACS.

  8. Model-free measurement of exchange market pressure

    NARCIS (Netherlands)

    Klaassen, F.J.G.M.; Jager, H.


    If there is exchange market pressure (EMP), monetary authorities can use the interest rate and official interventions to offset this depreciation tendency, or they can let the exchange rate change. We introduce a new approach to derive how these three variables should be combined to measure EMP.

  9. Surface pressure measurements for CFD code validation in hypersonic flow

    Energy Technology Data Exchange (ETDEWEB)

    Oberkampf, W.L.; Aeschliman, D.P.; Henfling, J.F.; Larson, D.E.


    Extensive surface pressure measurements were obtained on a hypersonic vehicle configuration at Mach 8. All of the experimental results were obtained in the Sandia National Laboratories Mach 8 hypersonic wind tunnel for laminar boundary layer conditions. The basic vehicle configuration is a spherically blunted 10{degrees} half-angle cone with a slice parallel with the axis of the vehicle. The bluntness ratio of the geometry is 10% and the slice begins at 70% of the length of the vehicle. Surface pressure measurements were obtained for angles of attack from {minus}10 to + 18{degrees}, for various roll angles, at 96 locations on the body surface. A new and innovative uncertainty analysis was devised to estimate the contributors to surface pressure measurement uncertainty. Quantitative estimates were computed for the uncertainty contributions due to the complete instrumentation system, nonuniformity of flow in the test section of the wind tunnel, and variations in the wind tunnel model. This extensive set of high-quality surface pressure measurements is recommended for use in the calibration and validation of computational fluid dynamics codes for hypersonic flow conditions.

  10. An Ultra Miniature MEMS Capacitor for Arterial Pressure Measurement (United States)

    Monga, A.; Vig, R.


    In biomedical field, there is a need for improving medical technologies to provide accurate diagnosis to patients. The objective is to develop a minimally invasive, implantable, pressure sensing system that continuously monitors physiological changes in real-time. For implementing, three different shapes of MEMS capacitive pressure sensor having same area of diaphragm 0.126 mm² is designed and simulated for blood pressure measurement. The various shapes which are taken are circular, square and rectangular. COMSOL multiphysics tool is used for simulation. For these shapes capacitance and deflection variation of membrane with applied pressure is studied. Result shows a sensitivity of 0.255 aF/kPa, 0.125 aF/kPa and 0.09 aF/kPa for circular, square and rectangular shape, respectively. So, circular MEMS capacitor provides the greater sensitivity than all other shapes and also provides greater deflection of diaphragm due to applied pressure of 40 kPa. Also deflection is more in circular diaphragm capacitive pressure sensor.

  11. Dynamic material strength measurement utilizing magnetically applied pressure-shear

    Directory of Open Access Journals (Sweden)

    Alexander C.S.


    Full Text Available Magnetically applied pressure-shear (MAPS is a recently developed technique used to measure dynamic material strength developed at Sandia National Laboratories utilizing magneto-hydrodynamic (MHD drive pulsed power systems. MHD drive platforms generate high pressures by passing a large current through a pair of parallel plate conductors which, in essence, form a single turn magnet coil. Lorentz forces resulting from the interaction of the self-generated magnetic field and the drive current repel the plates and result in a high pressure ramp wave propagating in the conductors. This is the principle by which the Sandia Z Machine operates for dynamic material testing. MAPS relies on the addition of a second, external magnetic field applied orthogonally to both the drive current and the self-generated magnetic field. The interaction of the drive current and this external field results in a shear wave being induced directly in the conductors. Thus both longitudinal and shear stresses are generated. These stresses are coupled to a sample material of interest where shear strength is probed by determining the maximum transmissible shear stress in the state defined by the longitudinal compression. Both longitudinal and transverse velocities are measured via a specialized velocity interferometer system for any reflector (VISAR. Pressure and shear strength of the sample are calculated directly from the VISAR data. Results of tests on several materials at modest pressures (∼10GPa will be presented and discussed.

  12. Dynamic material strength measurement utilizing magnetically applied pressure-shear (United States)

    Alexander, C. S.


    Magnetically applied pressure-shear (MAPS) is a recently developed technique used to measure dynamic material strength developed at Sandia National Laboratories utilizing magneto-hydrodynamic (MHD) drive pulsed power systems. MHD drive platforms generate high pressures by passing a large current through a pair of parallel plate conductors which, in essence, form a single turn magnet coil. Lorentz forces resulting from the interaction of the self-generated magnetic field and the drive current repel the plates and result in a high pressure ramp wave propagating in the conductors. This is the principle by which the Sandia Z Machine operates for dynamic material testing. MAPS relies on the addition of a second, external magnetic field applied orthogonally to both the drive current and the self-generated magnetic field. The interaction of the drive current and this external field results in a shear wave being induced directly in the conductors. Thus both longitudinal and shear stresses are generated. These stresses are coupled to a sample material of interest where shear strength is probed by determining the maximum transmissible shear stress in the state defined by the longitudinal compression. Both longitudinal and transverse velocities are measured via a specialized velocity interferometer system for any reflector (VISAR). Pressure and shear strength of the sample are calculated directly from the VISAR data. Results of tests on several materials at modest pressures (˜10GPa) will be presented and discussed.

  13. A history of intraocular pressure and its measurement. (United States)

    Stamper, Robert L


    Doctors have not always associated elevated intraocular pressure with the vision loss from glaucoma. Although several individuals appear to have noted firmness of the eye in this condition as far back as the 10th century, elevated intraocular pressure was not routinely assessed until the latter part of the 19th century. von Graefe developed the first instrument for measuring intraocular pressure in 1865. The first reasonably accurate instrument was the Maklakoff applanation tonometer of the late 19th century; it was in widespread use throughout Eastern Europe until relatively recently. Schiötz developed an indentation tonometer that was widely used throughout the world during the first two thirds of the 20th century. Goldmann's applanation tonometer of 1950 began the era of truly accurate intraocular pressure measurement. It is still the most widely used tonometer in the world. Other devices such as the McKay-Marg tonometer (or its offspring the Tono-Pen), the pneumatonometer, and airpuff applanation tonometers are gaining adherents. The dynamic contour tonometer is the first totally new concept in tonometry in over 100 years. It is probably the most accurate of all the tonometers and is relatively independent of corneal biomechanical properties unlike its predecessors. Transpalpebral tonometers are attractive as they do not require topical anesthesia; however, they add the biomechanical properties of the eyelid to the list of potential errors and have not proven very accurate. The future should, hopefully, bring tonometers that can give diurnal or even longer indications of intraocular pressure variation. Although intraocular pressure elevation (or its absence) no longer can be counted on for diagnostic purposes, the role of intraocular pressure in the management of glaucomatous optic neuropathy remains critical.

  14. Invasively Measured Aortic Systolic Blood Pressure and Office Systolic Blood Pressure in Cardiovascular Risk Assessment

    DEFF Research Database (Denmark)

    Laugesen, Esben; Knudsen, Søren T; Hansen, Klavs W


    Aortic systolic blood pressure (BP) represents the hemodynamic cardiac and cerebral burden more directly than office systolic BP. Whether invasively measured aortic systolic BP confers additional prognostic value beyond office BP remains debated. In this study, office systolic BP and invasively...

  15. Effects of Middle Ear Pressure on Otoacoustic Emission Measures. (United States)

    Zhang, Ming


    Otoacoustic emissions (OAEs) are used extensively in hearing evaluations. Changes in middle ear pressure may have an effect on both forward and backward transmission of signals through the middle ear. The effect that such changes have on OAEs may depend on extent of pressure change, stimulus frequency, and stimulus level. This study quantitatively evaluates the effects of these variables on distortion product OAEs (DPOAEs) and cochlear microphonic distortion products (CMDPs) for a wide range of stimuli. Pigmented adult guinea pigs were experimental subjects. An animal surgical model was established to manipulate pressure in the middle ear and CMDP and DPOAE were simultaneously measured. The effects on forward transmission were determined from the CMDP data. It was assumed that the DPOAE measures were affected by changes in both forward and backward transmission. The effects on backward transmission were determined from the DPOAE data after the effect on forward transmission were subtracted out. For all conditions the frequency ratio rm f_2/f_1 was held at 1.2 and the level ratio rm L_1/L_2 was 10 dB. The effects on forward transmission were similar to those for backward transmission in all experimental conditions. Negative pressure had a greater effect than positive pressure. Positive pressures of +10 and +20 cmH_2O affected transmission for low frequency stimuli (f_2 = 1620 and 2680 Hz) but had little effect for high frequency stimuli (f_2 = 6980 and 10250 Hz). Negative pressures of -2.5 to -10 cmH_2O affected transmission across all frequencies tested. The effect at low frequencies is hypothesized to be related to tympanic membrane stiffness. The effect of negative pressure at high frequencies may be related to change in the incudostapedial joint. The slope of growth function decreased with the pressure change for DPOAEs but changed little for CMDPs. The decrease in slope for DPOAEs suggests that the level chosen for analysis can influence the result of the

  16. Stratospheric water vapour as tracer for Vortex filamentation in the Arctic winter 2002/2003

    Directory of Open Access Journals (Sweden)

    M. Müller


    Full Text Available Balloon-borne frost point hygrometers measured three high-resolution profiles of stratospheric water vapour above Ny-Ålesund, Spitsbergen during winter 2002/2003. The profiles obtained on 12 December 2002 and on 17 January 2003 provide an insight into the vertical distribution of water vapour in the core of the polar vortex. The water vapour sounding on 11 February 2003 was obtained within the vortex edge region of the lower stratosphere. Here, a significant reduction of water vapour mixing ratio was observed between 16 and 19 km. The stratospheric temperatures indicate that this dehydration was not caused by the presence of polar stratospheric clouds or earlier PSC particle sedimentation. Ozone observations on this day indicate a large scale movement of the polar vortex and show laminae in the same altitude range as the water vapour profile. The link between the observed water vapour reduction and filaments in the vortex edge region is indicated in the results of the semi-lagrangian advection model MIMOSA, which show that adjacent filaments of polar and mid latitude air can be identified above the Spitsbergen region. A vertical cross-section produced by the MIMOSA model reveals that the water vapour sonde flew through polar air in the lowest part of the stratosphere below 425 K, then passed through filaments of mid latitude air with lower water vapour concentrations, before it finally entered the polar vortex above 450 K. These results indicate that on 11 February 2003 the frost point hygrometer measured different water vapour concentrations as the sonde detected air with different origins. Instead of being linked to dehydration due to PSC particle sedimentation, the local reduction in the stratospheric water vapour profile was in this case caused by dynamical processes in the polar stratosphere.

  17. The Droplets Condensate Centering in the Vapour Channel of Short Low Temperature Heat Pipes at High Heat Loads (United States)

    Seryakov, A. V.; Shakshin, S. L.; Alekseev, A. P.


    The results of experimental studies of the process of condensate microdroplets centering contained in the moving moist vapour in the vapour channel of short heat pipes (HPs) for large thermal loads are presented. A vapour channel formed by capillary-porous insert in the form of the inner Laval-liked nozzle along the entire length of the HP. In the upper cover forming a condensation surface in the HP, on the diametrical line are installed capacitive sensors, forming three capacitors located at different distances from the longitudinal axis of the vapour channel. With increasing heat load and the boil beginning in the evaporator a large amount of moist vapour in the vapour channel of HP occur the pressure pulsation with frequency of 400-500 Hz and amplitude up to 1·104Pa. These pulsations affect the moving of the inertial droplets subsystem of the vapour and due to the heterogeneity of the velocity profile around the particle flow in the vapour channel at the diameter of microdroplets occurs transverse force, called the Saffman force and shear microdroplets to the center of vapour channel. Using installed in the top cover capacitors we can record the radial displacement of the condensable microdroplets.

  18. Piston cylinder cell for high pressure ultrasonic pulse echo measurements

    Energy Technology Data Exchange (ETDEWEB)

    Kepa, M. W., E-mail:; Huxley, A. D. [SUPA, Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom); Ridley, C. J.; Kamenev, K. V. [Centre for Science at Extreme Conditions and School of Engineering, University of Edinburgh, Edinburgh EH9 3FD (United Kingdom)


    Ultrasonic techniques such as pulse echo, vibrating reed, or resonant ultrasound spectroscopy are powerful probes not only for studying elasticity but also for investigating electronic and magnetic properties. Here, we report on the design of a high pressure ultrasonic pulse echo apparatus, based on a piston cylinder cell, with a simplified electronic setup that operates with a single coaxial cable and requires sample lengths of mm only. The design allows simultaneous measurements of ultrasonic velocities and attenuation coefficients up to a pressure of 1.5 GPa. We illustrate the performance of the cell by probing the phase diagram of a single crystal of the ferromagnetic superconductor UGe{sub 2}.

  19. A comparison of methods for detonation pressure measurement (United States)

    Pachman, J.; Künzel, M.; Němec, O.; Majzlík, J.


    Detonation pressure is an important parameter describing the process of detonation. The paper compares three methods for determination of detonation pressure on the same explosive charge design. Pressed RDX/wax pellets with a density of 1.66 g cm^{-3} were used as test samples. The following methods were used: flyer plate method, impedance window method, and detonation electric effect. Photonic Doppler velocimetry was used for particle velocity measurements in the first two cases. The outputs of the three methods are compared to the literature values and to thermochemical calculation predictions.

  20. Low-speed pressure measurements using a luminescent coating system (United States)

    Brown, Owen Clayton

    In this work, the history of the development of the Pressure Sensitive Paint (PSP) technique in both the United States and Russia is first discussed in detail. A review of the various PSP tests conducted to date is given. A thorough discussion of the physics and chemistry of luminescent coatings is provided. The processes of converting intensity signals in digital data values are described; image processing procedures used to remove noise sources and convert intensity data into pressure measurements are reviewed. A general uncertainty analysis of the technique is then conducted. A baseline series of low-speed tests at M NASCAR racing model at various drafting orientations.

  1. Measurement of low shock pressures with piezoresistive carbon gauges. (United States)

    Krehl, P


    A new sensitive technique which permits the detection of small pressures in shock waves down to 5 bars with good time resolution has been developed. It consists of a pulsed double-compensated Wheatstone bridge in conjunction with piezoresistive carbon gauge transducers. It is shown that the advantages of piezoresistive gauges, such as short rise time, small dimensions, and in-material stress measurement, may be utilized for low shock pressure recording even in explosive environments, an area previously dominated by piezoelectric gauges. Comparative data for the two types of sensors are presented for shock tube side-on and head-on collision experiments and underwater explosions. This new development opens the possibility of PRG applications in classical fields of low shock pressure recording such as gas dynamics and underwater explosions.

  2. Water vapour solubility and conductivity study of the proton conductor BaCe(0.9 − x)ZrxY0.1O(3 − δ)

    DEFF Research Database (Denmark)

    Ricote, Sandrine; Bonanos, Nikolaos; Caboche, G:


    in the sample. The direct current conductivity has been measured as a function of oxygen partial pressure, at a water vapour partial pressure of 0.015 atm. The total conductivity has been resolved into a p-type and an ionic component using a fitting procedure appropriate to the assumed defect model....... An estimation of the protonic component was made by assuming a conductivity isotope effect between 1.4 and 1.8. The total conductivity, obtained using impedance spectroscopy has been measured as a function of temperature in the water and heavy water exchanged states. The activation energy has been found to be 0...

  3. Gas and vapour detection using polypyrrole

    NARCIS (Netherlands)

    Leur, R.H.M. van de; Waal, A. van der


    The vapours of organic solvents like toluene, butanon, and ethanol do effect the electrical conductivity of electrochemically synthesised polypyrrole. This property allows the use of polypyrrole in sensors for vapour detection. The conductivity is also a function of temperature and the history of

  4. Modified AC Wheatstone Bridge Network for Accurate Measurement of Pressure Using Strain Gauge Type Pressure Sensor

    Directory of Open Access Journals (Sweden)



    Full Text Available In order to achieve high quality of products at lesser cost, accurate measurement of different process variables is of vital importance in any industry. There are different well-established techniques of measurement and control instrumentations of these variables. In the resistive transducer like strain gauge, the small resistance generally changes linearly with a process variable like pressure but their measurement by usual AC Wheatstone bridge circuit may suffer from errors due to the effect of stray capacitance between bridge nodal points and ground and stray inductance on the strain gauge grid respectively. Though the conventional Wagner-Earth technique may be used to reduced the error but not suitable for continuous measurement. In the present paper, a modified operational amplifier based AC Wheatstone bridge measurement technique has been proposed in which the effect of stray capacitance and inductance is minimized. This bridge performance has been studied experimentally with the strain gauge type pressure transducer. The linear characteristics over a wide range of pressure with good repeatability, linearity and variable sensitivity have been described.

  5. Pressure measurements in a rapidly sheared turbulent wall layer (United States)

    Diwan, Sourabh; Morrison, Jonathan


    The aim of the present work is to improve understanding of the role of pressure fluctuations in the generation of coherent structures in wall-bounded turbulent flows, with particular regard to the rapid and slow source terms. The work is in part motivated by the recent numerical simulations of Sharma et al. (Phy. Fluids, 23, 2011), which showed the importance of pressure fluctuations (and their spatial gradients) in the dynamics of large-scale turbulent motions. Our experimental design consists of first generating a shearless boundary layer in a wind tunnel by passing a grid-generated turbulent flow over a moving floor whose speed is matched to the freestream velocity, and then shearing it rapidly by passing it over a stationary floor further downstream. Close to the leading edge of the stationary floor, the resulting flow is expected to satisfy the approximations of the Rapid Distortion Theory and therefore would be an ideal candidate for studying linear processes in wall turbulence. We carry out pressure measurements on the wall as well as within the flow - the former using surface mounted pressure transducers and the latter using a static pressure probe similar in design to that used by Tsuji et al. (J. Fluid. Mech. 585, 2007). We also present a comparison between the rapidly sheared flow and a more conventional boundary layer subjected to a turbulent free stream. We acknowledge the financial support from EPSRC (Grant No. EP/I037938).

  6. (Vapour + liquid) equilibrium in (N,N-dimethylacetamide + methanol + water) at the temperature 313.15 K[N,N-Dimethylacetamide; Water; Methanol; Amides; Binary mixtures; Ternary mixtures; (Vapour+liquid) equilibrium; Excess Gibbs free energy; Correlation

    Energy Technology Data Exchange (ETDEWEB)

    Zielkiewicz, Jan. E-mail:


    Total vapour pressures, measured at the temperature 313.15 K, are reported for the ternary mixture (N,N-dimethylacetamide + methanol + water), and for binary constituents (N,N-dimethylacetamide + methanol) and (N,N-dimethylacetamide + water). The present results are compared with previously obtained data for binary mixtures (amide + water) and (amide + methanol), where amide=N-methylformamide, N,N-dimethylformamide, N-methyl-acetamide, 2-pyrrolidinone and N-methylpyrrolidinone. Moreover, it was found that excess Gibbs free energy of mixing for binary mixtures varies roughly linearly with the molar volume of amide.

  7. Body mass index and blood pressure measurement during pregnancy.

    LENUS (Irish Health Repository)

    Hogan, Jennifer L


    OBJECTIVE: The accurate measurement of blood pressure requires the use of a large cuff in subjects with a high mid-arm circumference (MAC). This prospective study examined the need for a large cuff during pregnancy and its correlation with maternal obesity. METHODS: Maternal body mass index (BMI), fat mass, and MAC were measured. RESULTS: Of 179 women studied, 15.6% were obese. With a BMI of level 1 obesity, 44% needed a large cuff and with a BMI of level 2 obesity 100% needed a large cuff. CONCLUSION: All women booking for antenatal care should have their MAC measured to avoid the overdiagnosis of pregnancy hypertension.

  8. IR Temperature Measurement in Pressure-Shear Plate Impact (United States)

    Jiao, Tong; Malhotra, Pinkesh; Clifton, Rodney; School of Engineering, Brown University Team


    Pressure-Shear Plate Impact (PSPI) experiments on samples sandwiched between two hard plates have been developed previously for measuring the shearing resistance of materials at high strain rates, large inelastic shear strains, and high pressures. To enhance the value of such experiments in developing constitutive models for the dynamic response of materials, concurrent temperature measurements are being pursued by monitoring the infrared radiation emitted from the sample/rear-plate interface. The emitted radiation is collected by fast HgCdTe detectors through a pair of 90o off-axis parabolic reflectors. ZnSe is used as the rear plate (window) because its transmission band (0.6 μm -16 μm) covers an exceptionally wide range of wavelengths - extending beyond the cutoff wavelength of the IR detector. Moreover, ZnSe remains nominally linear-elastic up to a pressure of 12 GPa - encompassing the pressure range for most PSPI experiments. Because temperatures generated in PSPI experiments are modest, the emissivity of the interface is increased by applying a thin layer of SiC at the sample/window interface. The high shearing resistance of SiC ensures that the allowable range of shear stresses is not limited by the presence of the high-emissivity layer. Pilot experiments will be assessed for their potential and limitations. This work is supported by Air Force Office of Scientific Research.

  9. Falls event detection using triaxial accelerometry and barometric pressure measurement. (United States)

    Bianchi, Federico; Redmond, Stephen J; Narayanan, Michael R; Cerutti, Sergio; Celler, Branko G; Lovell, Nigel H


    A falls detection system, employing a Bluetooth-based wearable device, containing a triaxial accelerometer and a barometric pressure sensor, is described. The aim of this study is to evaluate the use of barometric pressure measurement, as a surrogate measure of altitude, to augment previously reported accelerometry-based falls detection algorithms. The accelerometry and barometric pressure signals obtained from the waist-mounted device are analyzed by a signal processing and classification algorithm to discriminate falls from activities of daily living. This falls detection algorithm has been compared to two existing algorithms which utilize accelerometry signals alone. A set of laboratory-based simulated falls, along with other tasks associated with activities of daily living (16 tests) were performed by 15 healthy volunteers (9 male and 6 female; age: 23.7 +/- 2.9 years; height: 1.74 +/- 0.11 m). The algorithm incorporating pressure information detected falls with the highest sensitivity (97.8%) and the highest specificity (96.7%).

  10. Surface Pressure Measurements of Atmospheric Tides Using Smartphones (United States)

    Price, Colin; Maor, Ron


    Similar to the oceans, the atmosphere also has tides that are measured in variations of atmospheric pressure. However, unlike the gravitational tides in the oceans, the atmospheric tides are caused primarily in the troposphere and stratosphere when the atmosphere is periodically heated by the sun, due to tropospheric absorption by water vapor and stratospheric absorption by ozone. Due to the forcing being always on the day side of the globe, the tides migrate around the globe following the sun (migrating tides) with a dominant periodicity of 12 hours (and less so at 24 hours). In recent years smartphones have been equipped with sensitive, cheap and reliable pressure sensors that can easily detect these atmospheric tides. By 2020 it is expected that there will be more than 6 billion smartphones globally, each measuring continuously atmospheric pressure at 1Hz temporal resolution. In this presentation we will present some control experiments we have performed with smartphones to monitor atmospheric tides, while also using random pressure data from more than 50,000 daily users via the WeatherSignal application. We conclude that smartphones are a useful tool for studying atmospheric tides on local and global scales.

  11. Twenty-four hour intraocular pressure measurements and home tonometry. (United States)

    Meier-Gibbons, Frances; Berlin, Michael S; Töteberg-Harms, Marc


    IOP is the only treatable risk factor contributing to glaucoma and most management and treatment of glaucoma is based on IOP. However, current IOP measurements are limited to office hours and control of glaucoma in many patients would benefit from the ability to monitor IOP diurnally so as not to miss abnormal pressures, which occur outside of office hours Consequently, to improve patient care, the ability to enable accurate and minimally disruptive diurnal IOP monitoring would improve caring for these patients. The studies we selected for this review can be divided into three categories: self-/home-tonometry, continuous invasive intraocular pressure measurements, and continuous noninvasive ocular measurements. The desire to obtain better insight in our patients' true diurnal IOP has led to the development of home-tonometers, in addition to extraocular and intraocular continuous pressure measurement devices. All of the devices have respective advantages and disadvantages, but none to date completely fulfills the goal of providing a true diurnal IOP profile.Video abstract

  12. (Vapour + liquid) equilibrium in (N,N-dimethylacetamide + ethanol + water) at the temperature 313.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Zielkiewicz, Jan [Department of Chemistry, Gdansk University of Technology, Narutowicza Str. 11/12, 80-952 Gdansk (Poland)]. E-mail:


    Total vapour pressures, measured at the temperature 313.15 K, are reported for the ternary mixture (N,N-dimethylacetamide + ethanol + water), and for binary constituent (N,N-dimethylacetamide + ethanol). The present results are also compared with previously obtained data for (amide + ethanol) binary mixtures, where amide = N-methylformamide, N,N-dimethylformamide, N-methylacetamide, 2-pyrrolidinone, and N-methylpyrrolidinone. We found that excess Gibbs free energy of mixing for binary (amide + ethanol) mixtures varies roughly linearly with the molar volume of amide.

  13. High Temperature High Pressure Thermodynamic Measurements for Coal Model Compounds

    Energy Technology Data Exchange (ETDEWEB)

    John C. Chen; Vinayak N. Kabadi


    The overall objective of this project is to develop a better thermodynamic model for predicting properties of high-boiling coal derived liquids, especially the phase equilibria of different fractions at elevated temperatures and pressures. The development of such a model requires data on vapor-liquid equilibria (VLE), enthalpy, and heat capacity which would be experimentally determined for binary systems of coal model compounds and compiled into a database. The data will be used to refine existing models such as UNIQUAC and UNIFAC. The flow VLE apparatus designed and built for a previous project was upgraded and recalibrated for data measurements for thk project. The modifications include better and more accurate sampling technique and addition of a digital recorder to monitor temperature, pressure and liquid level inside the VLE cell. VLE data measurements for system benzene-ethylbenzene have been completed. The vapor and liquid samples were analysed using the Perkin-Elmer Autosystem gas chromatography.

  14. The flexible asymmetric shock tube (FAST) : A Ludwieg tube facility for wave propagation measurements in high-temperature vapours of organic fluids

    NARCIS (Netherlands)

    Mathijssen, T.; Gallo, M.; Casati, E.; Nannan, N.R.; Zamfirescu, C.; Guardone, A.; Colonna, P.


    This paper describes the commissioning of the flexible asymmetric shock tube (FAST), a novel Ludwieg tube-type facility designed and built at Delft University of Technology, together with the results of preliminary experiments. The FAST is conceived to measure the velocity of waves propagating in

  15. Uncertainty of Five-Hole Probe Measurements. [of total flow pressure, static pressure, and flow (United States)

    Reichert, Bruce A.; Wendt, Bruce J.


    A new algorithm for five-hole probe calibration and data reduction using a non-nulling technique was developed, verified, and reported earlier (Wendt and Reichert, 1993). The new algorithm's simplicity permits an analytical treatment of the propagation of uncertainty in five-hole probe measurement. The objectives of the uncertainty analysis are to quantify the uncertainty of five-hole probe results (e.g., total pressure, static pressure, and flow direction) and to determine the dependence of the result uncertainty on the uncertainty of all underlying experimental and calibration measurands. This study outlines a general procedure that other researchers may use to determine five-hole probe result uncertainty and provides guidance for improving the measurement technique.

  16. Optical Measurement Technology for Calibratiing Inner Defects of Pressure Vessel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang Do; Chang, Seog Weon; Jhang, Kyung Young [Hanyang University, Seoul (Korea, Republic of)


    The pressure vessel may have crucial defects in its inner surfaces, which can be more dangerous than those in outer surfaces because the inner defects can hardly be measured or calibrated. Conventional methods for detecting or measuring the inner defects of pressure vessel have been utilizing ultrasonic, X-ray or eddy current. But the conventional NDE(Non-Destructive-Evaluation) methods are applied to limited area or environment because the prove or film must be located close to the objects although the methods are NDE tools. Recently, optical measurement technologies for detecting the inner defects such as cracks, flaws or corrosions are utilized very much. The optical measurement technologies are known as much useful as to have the capabilities of short working time, non-contact and full-field measurement. Among them, shearography is considered to be one of the most available tools, because of its feature of not requiring strict environmental stability, which is essential to other optical tools. In this study, the availability of the optical measurement technology using shearography for detecting and calibrating the inner defects is verified.

  17. Interpretation of Strain Measurements on Nuclear Pressure Vessels

    DEFF Research Database (Denmark)

    Andersen, Svend Ib Smidt; Engbæk, Preben


    Selected results from strain measurements on four nuclear pressure vessels are presented and discussed. The measurements were made in several different regions of the vessels: transition zones in vessel heads, flanges and bottom parts, nozzles, internal vessel structure and flange bolts. The resu......Selected results from strain measurements on four nuclear pressure vessels are presented and discussed. The measurements were made in several different regions of the vessels: transition zones in vessel heads, flanges and bottom parts, nozzles, internal vessel structure and flange bolts....... The results presented are based on data obtained by approximately 700 strain-gauges, and a comprehensive knowledge of the quality obtained by such measurements is established. It is shown that a thorough control procedure before and after the test as well as a detailed knowledge of the behaviour of the signal...... from the individual gauges during the test is necessary. If this is omitted, it can be extremely difficult to distinguish between the real structural behaviour and a malfunctioning of a specific gauge installation. In general, most of the measuring results exhibit a very linear behaviour...

  18. Axial mercury segregation in direct current operated low-pressure argon mercury gas discharges: Part I. Experimental (United States)

    Gielen, John W. A. M.; de Groot, Simon; van der Mullen, Joost J. A. M.


    Due to cataphoresis, axial segregation of mercury will occur when the gas discharge of a fluorescent lamp is operated by means of a direct current. A consequence of this is a non-uniform axial luminance distribution along the lamp. To determine the degree of axial mercury segregation experimentally, axial luminance distributions have been measured which are converted into axial mercury vapour pressure distributions by an appropriate calibration method. The mercury segregation has been investigated for variations in lamp tube radius (3.6-4.8 mm), argon buffer gas pressure (200-600 Pa) and lamp current (100-250 mA) at mercury vapour pressures set at the anode in the range from 0.2 to 9.0 Pa. From the experiments it has been concluded that the mercury vapour pressure gradient at any axial position for a certain lamp tube diameter, argon pressure and lamp current depends on the local mercury vapour pressure. This observation is in contrast to assumptions made in earlier modelling publications in which one mercury vapour pressure gradient is used for all axial positions. By applying a full factorial design, an empirical relation of the mercury segregation is found for any set of parameters inside the investigated parameter ranges.

  19. Cardiovascular Risk in Hypertension in Relation to Achieved Blood Pressure Using Automated Office Blood Pressure Measurement. (United States)

    Myers, Martin G; Kaczorowski, Janusz; Dolovich, Lisa; Tu, Karen; Paterson, J Michael


    The SPRINT (Systolic Blood Pressure Intervention Trial) reported that some older, higher risk patients might benefit from a target systolic blood pressure (BP) of <120 versus <140 mm Hg. However, it is not yet known how the BP target and measurement methods used in SPRINT relate to cardiovascular outcomes in real-world practice. SPRINT used the automated office BP technique, which requires the patient to be resting quietly and alone, with multiple readings being recorded automatically using an electronic oscillometric sphygmomanometer. We studied the relationship between achieved automated office BP at baseline and cardiovascular events in 6183 community-dwelling residents of Ontario aged ≥66 years who were receiving antihypertensive therapy and followed for a mean of 4.6 years. Adjusted hazard ratios (95% confidence intervals) were computed for 10 mm Hg increments in achieved automated office BP at baseline using Cox proportional hazards regression and the BP category with the lowest event rate as the reference category. Based on 904 fatal and nonfatal cardiovascular events, the nadir of cardiovascular events was at the systolic pressure category of 110 to 119 mm Hg, which was lower than the next highest category of 120 to 129 mm Hg (hazard ratio 1.30 [1.01, 1.66]). The hazard ratio for diastolic pressure was relatively unchanged above 60 mm Hg. Pulse pressure exhibited an increase in hazard ratio (1.33 [1.02, 1.72]) at ≥80 mm Hg. These results using automated office BP measurement in a usual treatment setting extend the finding in SPRINT of an optimum target systolic BP of <120 mm Hg to routine clinical practice. © 2016 American Heart Association, Inc.

  20. A noncontact intraocular pressure measurement device using a micro reflected air pressure sensor for the prediagnosis of glaucoma (United States)

    Kim, Kyoung Hwan; Kim, Byeong Hee; Seo, Young Ho


    This study investigates a novel, portable tonometer using a micro reflected air pressure sensor for the prediagnosis of glaucoma. Because glaucoma progresses slowly and is not painful, glaucoma patients require a portable prediagnosis system to periodically measure intraocular pressure at home. Conventionally, intraocular pressure is measured by an air-puff tonometer whereby the cornea is deformed by a short pulse of air pressure and the magnitude of the corneal deformation is measured by optic systems such as a combination of laser- and photodiodes. In this study, a micro reflected air pressure sensor was designed, fabricated, and tested in order to measure the magnitude of corneal deformation without optic systems. In an experimental study, artificial eyes with different internal pressures were fabricated and these pressures were measured by the aforementioned system.

  1. Computerized invasive measurement of time-dependent intraocular pressure

    Directory of Open Access Journals (Sweden)

    T.V.O. Campos


    Full Text Available Several methods have been described to measure intraocular pressure (IOP in clinical and research situations. However, the measurement of time varying IOP with high accuracy, mainly in situations that alter corneal properties, has not been reported until now. The present report describes a computerized system capable of recording the transitory variability of IOP, which is sufficiently sensitive to reliably measure ocular pulse peak-to-peak values. We also describe its characteristics and discuss its applicability to research and clinical studies. The device consists of a pressure transducer, a signal conditioning unit and an analog-to-digital converter coupled to a video acquisition board. A modified Cairns trabeculectomy was performed in 9 Oryctolagus cuniculus rabbits to obtain changes in IOP decay parameters and to evaluate the utility and sensitivity of the recording system. The device was effective for the study of kinetic parameters of IOP, such as decay pattern and ocular pulse waves due to cardiac and respiratory cycle rhythm. In addition, there was a significant increase of IOP versus time curve derivative when pre- and post-trabeculectomy recordings were compared. The present procedure excludes corneal thickness and error related to individual operator ability. Clinical complications due to saline infusion and pressure overload were not observed during biomicroscopic evaluation. Among the disadvantages of the procedure are the requirement of anesthesia and the use in acute recordings rather than chronic protocols. Finally, the method described may provide a reliable alternative for the study of ocular pressure dynamic alterations in man and may facilitate the investigation of the pathogenesis of glaucoma.

  2. How to measure low-pressure steam boiler efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Katrakis, J.T. (Katrakis and Associates, Chicago, IL (United States)); Zawacki, T.S. (Phillips Engineering, St. Joseph, MI (United States))


    Low-pressure central steam systems are the predominant type of space heating system in pre-World War II multifamily housing throughout the northern urban areas of the US. In Chicago alone, over 300,000 low to middle income residences are heated in this manner. Heating costs in these buildings are frequently over 50% higher than for buildings with newer hot water or forced air systems. High costs are a major cause of the precarious financial picture of these older low to moderate income buildings. Efforts to address this problem include research aimed at identifying effective and affordable ways of enhancing the efficiency of the heating systems in these buildings. The boilers are one major area where efficiency improvements are possible. These buildings use intermediate-sized low-pressure steam boilers that are also commonly found in commercial, institutional and small industrial applications for space and process water heating. As a group, their performance is the least well documented among all the heating plant technologies. Ranging in input capacity from 300,000 Btu per hour to 4,000,000 Btu per hour (87.9 kW to 1,172 kW), they are too small to warrant the cost of installing and maintaining standard commercially available steam metering equipment. Yet, they are larger than the heating plants that are subject to the federally-mandated AFUE testing. As part of the research to improve the efficiency of these heating systems, it was necessary to develop simple and affordable methods to measure the seasonal efficiency of low-pressure steam boilers in buildings. As reported in this article two methods were developed to measure the in-situ seasonal efficiency of these boilers: a benchmark method based on ANSI standards for measuring the flue and jacket losses; and a simplified method, the Time-to-Make-Steam (TTMS) method that is easy to apply and appropriate for low-pressure steam boilers.

  3. Prospective blood pressure measurement in renal transplant recipients

    Directory of Open Access Journals (Sweden)

    V G David


    Full Text Available Blood pressure (BP control at home is difficult when managed only with office blood pressure monitoring (OBPM. In this prospective study, the reliability of BP measurements in renal transplant patients with OBPM and home blood pressure monitoring (HBPM was compared with ambulatory blood pressure monitoring (ABPM as the gold standard. Adult patients who had living-related renal transplantation from March 2007 to February 2008 had BP measured by two methods; OBPM and ABPM at pretransplantation, 2 nd , 4 th , 6 th , and 9 th months and all the three methods : OBPM, ABPM, and HBPM at 6 months after transplantation. A total of 49 patients, age 35 ± 11 years, on prednisolone, tacrolimus, and mycophenolate were evaluated. A total of 39 were males (79.6%. Systolic BP (SBP and diastolic BP (DBP measured by OBPM were higher than HBPM when compared with ABPM. When assessed using OBPM and awake ABPM, both SBP and DBP were significantly overestimated by OBPM with mean difference of 3-12 mm Hg by office SBP and 6-8 mm Hg for office DBP. When HBPM was compared with mean ABPM at 6 months both the SBP and DBP were overestimated by and 7 mm Hg respectively. At 6 months post transplantation, when compared with ABPM, OBPM was more specific than HBPM in diagnosing hypertension (98% specificity, Kappa : 0.88 vs. 89% specificity, Kappa : 0.71. HBPM was superior to OBPM in identifying patients achieving goal BP (89% specificity, Kappa : 0.71 vs. 50% specificity Kappa : 0.54. In the absence of a gold standard for comparison the latent class model analysis still showed that ABPM was the best tool for diagnosing hypertension and monitoring patients reaching targeted control. OBPM remains an important tool for the diagnosis and management of hypertension in renal transplant recipients. HBPM and ABPM could be used to achieve BP control.

  4. Quality of blood pressure measurement in community health centres. (United States)

    Sandoya-Olivera, Edgardo; Ferreira-Umpiérrez, Augusto; Machado-González, Federico

    To determine the quality of the blood pressure measurements performed during routine care in community health centres. An observational, cross-sectional study was conducted in 5 private and public health centres in Maldonado, Uruguay, in July-August 2015. The observations were made during the measurements performed by health personnel, using the requirements established by the American Heart Association. An analysis was made on 36 variables that were grouped in categories related to environment, equipment, interrogation, patient, and observer. Statistical analysis was performed using Chi2 test or Fisher test. Statistical significance was considered to be less than 5% (pattitude (82%), and intermediate in the attitudes of the operator (64%), and poor in relation to the interrogation (18%), with the mean of correct variables per measurement being 69%. The main flaws in the procedure were the operator. The measurement of blood pressure is a manoeuvre that healthcare professionals perform thousands of times a year. If the measurement is used for the diagnosis and/or chronic management of arterial hypertension, not systematically applying the established recommendations leads to an inappropriate care of a very significant number of patients. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

  5. Solvation pressure as real pressure: I. Ethanol and starch under negative pressure

    CERN Document Server

    Uden, N W A V; Faux, D A; Tanczos, A C; Howlin, B; Dunstan, D J


    The reality of the solvation pressure generated by the cohesive energy density of liquids is demonstrated by three methods. Firstly, the Raman spectrum of ethanol as a function of cohesive energy density (solvation pressure) in ethanol-water and ethanol-chloroform mixtures is compared with the Raman spectrum of pure ethanol under external hydrostatic pressure and the solvation pressure and hydrostatic pressure are found to be equivalent for some transitions. Secondly, the bond lengths of ethanol are calculated by molecular dynamics modelling for liquid ethanol under pressure and for ethanol vapour. The difference in bond lengths between vapour and liquid are found to be equivalent to the solvation pressure for the C-H sub 3 , C-H sub 2 and O-H bond lengths, with discrepancies for the C-C and C-O bond lengths. Thirdly, the pressure-induced gelation of potato starch is measured in pure water and in mixtures of water and ethanol. The phase transition pressure varies in accordance with the change in solvation pre...

  6. A user's guide to intra-abdominal pressure measurement.

    LENUS (Irish Health Repository)

    Sugrue, Michael


    The intra-abdominal pressure (IAP) measurement is a key to diagnosing and managing critically ill medical and surgical patients. There are an increasing number of techniques that allow us to measure the IAP at the bedside. This paper reviews these techniques. IAP should be measured at end-expiration, with the patient in the supine position and ensuring that there is no abdominal muscle activity. The intravesicular IAP measurement is convenient and considered the gold standard. The level where the mid-axillary line crosses the iliac crest is the recommended zero reference for the transvesicular IAP measurement; moreover, marking this level on the patient increases reproducibility. Protocols for IAP measurement should be developed for each ICU based on the locally available tools and equipment. IAP measurement techniques are safe, reproducible and accurate and do not increase the risk of urinary tract infection. Continuous IAP measurement may offer benefits in specific situations in the future. In conclusion, the IAP measurement is a reliable and essential adjunct to the management of patients at risk of intra-abdominal hypertension.

  7. Extraction of airfoil data using PIV and pressure measurements

    DEFF Research Database (Denmark)

    Yang, Hua; Shen, Wen Zhong; Sørensen, Jens Nørkær


    A newly developed technique for determining the angle of attack (AOA) on a rotating blade is used to extract AOAs and airfoil data from measurements obtained during the MEXICO (Model rotor EXperiments in COntrolled conditions) rotor experiment. Detailed surface pressure and Particle Image...... Velocimetry (PIV) flow fields at different rotor azimuth positions are examined for determining sectional airfoil data. The AOA is derived locally by determining the local circulation on the blade from pressure data and subtracting the induction of the bound circulation from the local velocity. The derived...... airfoil data are compared to 2D data from wind tunnel experiments and XFOIL computations. The comparison suggests that the rotor is subject to severe 3D effects originating from the geometry of the rotor, and explains why the Blade Element Momentum technique with 2D airfoil data over‐predicts the loading...

  8. A batch fabricated capacitive pressure sensor with an integrated Guyton capsule for interstitial fluid pressure measurement (United States)

    Maleki, Teimour; Fogle, Benjamin; Ziaie, Babak


    In this paper, we present the design, fabrication and test of a batch fabricated capacitive pressure sensor with an integrated Guyton capsule for interstitial fluid pressure measurement. The sensor is composed of 12 µm thick single crystalline silicon membrane and a 3 µm gap, hermetically sealed through silicon-glass anodic bonding. A novel batch scale method for creating electrical feed-throughs inside the sealed capacitor chamber is developed. The Guyton capsule consists of an array of 10 µm diameter access holes etched onto a silicon back-plate separated from the silicon sensing membrane by a gap of 5 µm. The presence of the Guyton capsule (i.e. plates with access holes plus the gap separating them from the sensing membrane) allows for the ingress of interstitial fluid inside the 5 µm gap following the implantation, thus, providing an accurate measurement of interstitial fluid pressure. The fabricated sensor is 3 × 2 × 0.42 mm3 in dimensions and has a maximum sensitivity of 10 fF mmHg-1.

  9. An insole pressure measurement system: repeatability of postural data. (United States)

    Bauer, J A; Cauraugh, J H; Tillman, M D


    This study analyzed the ability of an in-shoe plantar pressure measurement system to provide repeatable measurements of postural sway data for both healthy and clinical patients. Each participant's in-shoe pressure data were recorded for three trials during each test session during quiet stance. Healthy individuals (n = 9) participated on three consecutive days while clinical participants (n = 5) were tested on one day. Nine response variables were measured to assess their postural stability. Intrasubject measures were evaluated using the Kerlinger reliability procedure. Values provided directly by the Parotec System for a single day of testing yielded the following average coefficients: r = 0.95 (left), r = 0.97 (right) with mean coefficient values from the three day tests of: r = 0.98 (left), r = 0.98 (right). Variables calculated from raw data on a single day produced mean coefficients of: r = 0.77 (left), r = 0.76 (right) and over three days of: r = 0.65 (left), r = 0.66 (right). The ability to record highly reproducible data of postural sway parameters should assist clinicians to treat patients more confidently for balance deficiencies.

  10. Pathophysiology of glaucoma and continuous measurements of intraocular pressure. (United States)

    Sit, Arthur J; Liu, John H K


    Glaucoma is a leading cause of visual impairment and blindness worldwide. The main risk factor for glaucoma is an elevated intraocular pressure (IOP), which is also the only currently treatable risk factor. Despite its importance, our understanding of IOP is incomplete and our ability to measure IOP is limited. IOP is known to undergo both random fluctuations as well as variations following a circadian pattern. In humans, IOP is highest at night and lower during the daytime, largely due to changes in body position, although other factors appear to contribute. In rabbits, IOP is also highest at night and lower during the day, likely due to circadian variations in sympathetic nervous system activity. Random and circadian IOP variations may be important to glaucoma pathogenesis, independent of the diurnal IOP level. However, due to limitations with current IOP measurement technology, clinical practice typically involves only a few IOP measurements per year. As well, current technology does not allow 24-hour monitoring of pressure without the use of sleep laboratories or hospital admission. Two strategies for automating IOP measurement are temporary (non-invasive) monitoring and permanent (implantable) monitoring. Efforts at developing devices to allow continuous IOP monitoring have occurred for over 40 years without producing a clinical device. Current technological progress would seem to suggest that such devices are possible at this time, and a review of previous attempts provides guidelines for their development.

  11. Agreement between two oscillometric blood pressure technologies and invasively measured arterial pressure in the dog. (United States)

    da Cunha, Anderson F; Ramos, Sara J; Domingues, Michelle; Beaufrère, Hugues; Shelby, Amanda; Stout, Rhett; Acierno, Mark J


    To compare two commonly used oscillometric technologies for obtaining noninvasive blood pressure (NIBP) measurements and to determine if there is a difference in agreement between these systems and invasive blood pressure (IBP) measurements. Prospective, experimental study. Twenty adult laboratory dogs. Each dog was anesthetized and its median caudal artery catheterized for IBP monitoring. An NIBP cuff was placed in the middle third of the antebrachium and attached to either monitor-1 or monitor-2. Four pairs of concurrent NIBP and IBP measurements were recorded with each monitor. Agreement between IBP and NIBP measurements was explored using Bland-Altman analysis, as well as the American College of Veterinary Internal Medicine (ACVIM) and Association for the Advancement of Medical Instrumentation (AAMI) guidelines for the validation of NIBP devices. Both NIBP technologies produced results that met the ACVIM and AAMI guidelines for the validation of NIBP devices. For monitor-1, analyses of agreement showed biases of 0.2 mmHg [95% limits of agreement (LoA) -11.8 to 12.3 mmHg] in systolic arterial pressure (SAP) values, -2.6 mmHg (95% LoA -14.4 to 9.1 mmHg) in diastolic arterial pressure (DAP) values, and -2.5 mmHg (95% LoA -12.7 to 7.3 mmHg) in mean arterial pressure (MAP) values. For monitor-2, analyses of agreement showed biases of 3.4 mmHg (95% LoA -8.7 to 15.5 mmHg) in SAP values, 2.2 mmHg (95% LoA -6.6 to 10.9 mmHg) in DAP values, and 1.6 mmHg (95% LoA -5.9 to 8.9 mmHg) in MAP values. Multi-function monitors can contain components from various manufacturers. Clinicians should consider whether these have been validated in the species to be monitored. Both of the technologies studied here seem appropriate for use in dogs. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

  12. Comparison of three protocols for measuring the maximal respiratory pressures

    Directory of Open Access Journals (Sweden)

    Isabela Maria B. Sclauser Pessoa

    Full Text Available Introduction To avoid the selection of submaximal efforts during the assessment of maximal inspiratory and expiratory pressures (MIP and MEP, some reproducibility criteria have been suggested. Criteria that stand out are those proposed by the American Thoracic Society (ATS and European Respiratory Society (ERS and by the Brazilian Thoracic Association (BTA. However, no studies were found that compared these criteria or assessed the combination of both protocols. Objectives To assess the pressure values selected and the number of maneuvers required to achieve maximum performance using the reproducibility criteria proposed by the ATS/ERS, the BTA and the present study. Materials and method 113 healthy subjects (43.04 ± 16.94 years from both genders were assessed according to the criteria proposed by the ATS/ERS, BTA and the present study. Descriptive statistics were used for analysis, followed by ANOVA for repeated measures and post hoc LSD or by Friedman test and post hoc Wilcoxon, according to the data distribution. Results The criterion proposed by the present study resulted in a significantly higher number of maneuvers (MIP and MEP – median and 25%-75% interquartile range: 5[5-6], 4[3-5] and 3[3-4] for the present study criterion, BTA and ATS/ERS, respectively; p < 0.01 and higher pressure values (MIP – mean and 95% confidence interval: 103[91.43-103.72], 100[97.19-108.83] and 97.6[94.06-105.95]; MEP: median and 25%-75% interquartile range: 124.2[101.4-165.9], 123.3[95.4-153.8] and 118.4[95.5-152.7]; p < 0.05. Conclusion The proposed criterion resulted in the selection of pressure values closer to the individual’s maximal capacity. This new criterion should be considered in future studies concerning MIP and MEP measurements.

  13. Energy expenditure estimation using triaxial accelerometry and barometric pressure measurement. (United States)

    Voleno, Matteo; Redmond, Stephen J; Cerutti, Sergio; Lovell, Nigel H


    Energy expenditure (EE) is a parameter of great relevance in studies involving the assessment of physical activity. However, most reliable techniques for EE estimation are impractical for use in free-living environments, and those which are practically useful often poorly track EE when the subject is working to change their altitude, for example when ascending or descending stairs or slopes. The aim of this study is to evaluate the utility of adding barometric pressure related features, as a surrogate measure for altitude, to existing accelerometry related features to estimate the subject's EE. The EE estimation system described is based on a triaxial accelerometer (triax) and a barometric pressure sensor. The device is wireless, with Bluetooth connectivity for data retrieval, and is mounted at the subject's waist. Using a number of features extracted from the triax and barometric pressure signals, a linear model is trained for EE estimation. This EE estimation model is compared to its counterpart, which solely utilizes accelerometry signals. A protocol (comprising lying, sitting, standing, walking phases) was performed by 13 healthy volunteers (8 male and 5 female; age: 23.8 ± 3.7 years; weight: 70.5 ± 14.9 kg), whose instantaneous oxygen uptake was measured by means of an indirect calorimetry system. The model incorporating barometric pressure information estimated the oxygen uptake with the lowest mean square error of 4.5 ± 1.7 (mlO(2).min(-1).kg(-1))(2), in comparison to 7.1 ± 2.3 (mlO(2).min(-1).kg(-1))(2) using only accelerometry-based features.


    Energy Technology Data Exchange (ETDEWEB)

    Vinayak N. Kabadi


    The flow VLE apparatus designed and built for a previous project was upgraded and recalibrated for data measurements for this project. The modifications include better and more accurate sampling technique, addition of a digital recorder to monitor temperature and pressure inside the VLE cell, and a new technique for remote sensing of the liquid level in the cell. VLE data measurements for three binary systems, tetralin-quinoline, benzene--ethylbenzene and ethylbenzene--quinoline, have been completed. The temperature ranges of data measurements were 325 C to 370 C for the first system, 180 C to 300 C for the second system, and 225 C to 380 C for the third system. The smoothed data were found to be fairly well behaved when subjected to thermodynamic consistency tests. SETARAM C-80 calorimeter was used for incremental enthalpy and heat capacity measurements for benzene--ethylbenzene binary liquid mixtures. Data were measured from 30 C to 285 C for liquid mixtures covering the entire composition range. An apparatus has been designed for simultaneous measurement of excess volume and incremental enthalpy of liquid mixtures at temperatures from 30 C to 300 C. The apparatus has been tested and is ready for data measurements. A flow apparatus for measurement of heat of mixing of liquid mixtures at high temperatures has also been designed, and is currently being tested and calibrated.

  15. A high pressure cell for simultaneous osmotic pressure and x-ray diffraction measurements (United States)

    Gauthé, Béatrice L. L. E.; Heron, Andrew J.; Seddon, John M.; Ces, Oscar; Templer, Richard H.


    In this paper, we report on a novel osmotic cell, developed to simultaneously subject a sample to osmotic stress and measure structural changes by small angle x-ray diffraction. The osmotic cell offers many advantages over more conventional methods of osmotically stressing soft materials to measure their structural response. In particular, a full osmotic analysis can be performed with a single small sample (25 μl). This reduces sample handling and the associated systematic errors, as well as enabling tight control and monitoring of the thermodynamic environment during osmosis, thereby increasing measurement precision. The cell design enables control of osmotic pressure to ±0.04 bar over a pressure range of 1-100 bar, and temperature control to ±0.05 °C. Under these conditions, the lattice spacing in lyotropic structures was resolved to better than ±0.005 Å. Using the osmotic cell, we demonstrate good agreement with previous conventional measurements on the energy of dehydrating the fluid lamellar phase of dioleoylphosphatidylcholine in water.

  16. Increase of Short-Term Heart Rate Variability Induced by Blood Pressure Measurements during Ambulatory Blood Pressure Monitoring


    Attila Frigy; Annamária Magdás; Victor-Dan Moga; Ioana Georgiana Coteț; Miklós Kozlovszky; László Szilágyi


    Objective. The possible effect of blood pressure measurements per se on heart rate variability (HRV) was studied in the setting of concomitant ambulatory blood pressure monitoring (ABPM) and Holter ECG monitoring (HM). Methods. In 25 hypertensive patients (14 women and 11 men, mean age: 58.1 years), 24-hour combined ABPM and HM were performed. For every blood pressure measurement, 2-minute ECG segments (before, during, and after measurement) were analyzed to obtain time domain parameters of H...

  17. Corrigendum to “Relative humidity effects on water vapour fluxes measured with closed-path eddy-covariance systems with short sampling lines” [Agric. Forest Meteorol. 165 (2012) 53–63

    DEFF Research Database (Denmark)

    Fratini, Gerardo; Ibrom, Andreas; Arriga, Nicola


    It has been formerly recognised that increasing relative humidity in the sampling line of closed-path eddy-covariance systems leads to increasing attenuation of water vapour turbulent fluctuations, resulting in strong latent heat flux losses. This occurrence has been analyzed for very long (50 m)...

  18. Non-invasive continuous finger blood pressure measurement during orthostatic stress compared to intra-arterial pressure

    NARCIS (Netherlands)

    Imholz, B. P.; Settels, J. J.; van der Meiracker, A. H.; Wesseling, K. H.; Wieling, W.


    The aim of the study was to evaluate whether invasive blood pressure responses to orthostatic stress can be replaced by non-invasive continuous finger blood pressure responses. DESIGN - Intrabrachial and Finapres blood pressures were simultaneously measured during passive head up tilt and during


    DEFF Research Database (Denmark)

    Henningsen, Poul; Arentoft, Mogens; Lagergren, Jonas


    A load transducer has been developed to measure the contact forces in the deformation zone during rolling. The transducer consists of a strain gauge equipped insert, embedded in the surface of the roll. The length of the insert exceeds the contact length between material and roll. By analyzing...... the output from the transducer, the friction stress and normal pressure in the contact zone can be determined. The new concept differs from existing pin designs by a lower disturbance of lubricant film and material flow and limited penetration of material between transducer and roll. Aluminum, cupper...... and steel strips with a width of 40 mm was rolled with reduction varying from 2.7% to 29%, in a pilot mill. For evaluating the transducer, the measured contact forces are compared with external measurements of roll separating forces and torque. The determined friction coefficients are compared with values...

  20. Step Prediction During Perturbed Standing Using Center Of Pressure Measurements

    Directory of Open Access Journals (Sweden)

    Milos R. Popovic


    Full Text Available The development of a sensor that can measure balance during quiet standing and predict stepping response in the event of perturbation has many clinically relevant applica- tions, including closed-loop control of a neuroprothesis for standing. This study investigated the feasibility of an algorithm that can predict in real-time when an able-bodied individual who is quietly standing will have to make a step to compensate for an external perturbation. Anterior and posterior perturbations were performed on 16 able-bodied subjects using a pul- ley system with a dropped weight. A linear relationship was found between the peak center of pressure (COP velocity and the peak COP displacement caused by the perturbation. This result suggests that one can predict when a person will have to make a step based on COP velocity measurements alone. Another important feature of this finding is that the peak COP velocity occurs considerably before the peak COP displacement. As a result, one can predict if a subject will have to make a step in response to a perturbation sufficiently ahead of the time when the subject is actually forced to make the step. The proposed instability detection algorithm will be implemented in a sensor system using insole sheets in shoes with minitur- ized pressure sensors by which the COPv can be continuously measured. The sensor system will be integrated in a closed-loop feedback system with a neuroprosthesis for standing in the near future.

  1. Continuous intraocular pressure (IOP) measurement during glaucoma drainage device implantation. (United States)

    Gouws, Pieter; Moss, Edward B; Trope, Graham E; Ethier, C Ross


    To measure the effect of the implantation of a glaucoma drainage device on the intraocular pressure (IOP) during the implantation surgery. We implanted telemetry devices into 1 eye each of 3 white New Zealand rabbits. Once the telemetry was found to be working and the rabbits had fully recovered from surgery, we implanted a glaucoma drainage device into the same eye while continually monitoring the IOP with the telemetry devices. During surgery IOP was extremely variable, however, extremely high pressures were recorded in association with suturing and viscoelastic injection. The fact that pressures are significantly raised during some surgical events should make surgeons aware that manipulations need to be kept as short as possible to prevent further potential damage to glaucomatous optic nerves. There is a possibility of dramatically raising the IOP during surgery, specifically in complicated cases requiring prolonged manipulation and/or forcible deepening of the anterior chamber. In such cases, it may be a good idea to time the duration of manipulations to prevent prolonged episodes of elevated IOP.

  2. A Procedure for Measuring Microplastics using Pressurized Fluid Extraction. (United States)

    Fuller, Stephen; Gautam, Anil


    A method based on pressurized fluid extraction (PFE) was developed for measuring microplastics in environmental samples. This method can address some limitations of the current microplastic methods and provide laboratories with a simple analytical method for quantifying common microplastics in a range of environmental samples. The method was initially developed by recovering 101% to 111% of spiked plastics on glass beads and was then applied to a composted municipal waste sample with spike recoveries ranging from 85% to 94%. The results from municipal waste samples and soil samples collected from an industrial area demonstrated that the method is a promising alternative for determining the concentration and identity of microplastics in environmental samples.

  3. Measuring the local pressure amplitude in microchannel acoustophoresis

    DEFF Research Database (Denmark)

    Barnkob, Rune; Augustsson, Per; Laurell, Thomas


    /glass microchannels. The system is actuated by a PZT piezo transducer attached beneath the chip and driven by an applied ac voltage near its eigenfrequency of 2 MHz. For a given frequency a number of particle tracks are recorded by a CCD camera and fitted to a theoretical expression for the acoustophoretic motion......A new method is reported on how to measure the local pressure amplitude and the Q factor of ultrasound resonances in microfluidic chips designed for acoustophoresis of particle suspensions. The method relies on tracking individual polystyrene tracer microbeads in straight water-filled silicon...

  4. Autonomous Chemical Vapour Detection by Micro UAV

    Directory of Open Access Journals (Sweden)

    Kent Rosser


    Full Text Available The ability to remotely detect and map chemical vapour clouds in open air environments is a topic of significant interest to both defence and civilian communities. In this study, we integrate a prototype miniature colorimetric chemical sensor developed for methyl salicylate (MeS, as a model chemical vapour, into a micro unmanned aerial vehicle (UAV, and perform flights through a raised MeS vapour cloud. Our results show that that the system is capable of detecting MeS vapours at low ppm concentration in real-time flight and rapidly sending this information to users by on-board telemetry. Further, the results also indicate that the sensor is capable of distinguishing “clean” air from “dirty”, multiple times per flight, allowing us to look towards autonomous cloud mapping and source localization applications. Further development will focus on a broader range of integrated sensors, increased autonomy of detection and improved engineering of the system.

  5. On water vapour transfer inside frozen packs

    National Research Council Canada - National Science Library

    Heiss, R


    In the case of various foodstuffs, irreversible water- vapour transporations within the frozen packages can bring about a distinct quality drop caused by damage to the surface of the material as a result of drying out (freezer burn...

  6. Continuous cardiac output measurement: arterial pressure analysis versus thermodilution technique during cardiac surgery with cardiopulmonary bypass

    NARCIS (Netherlands)

    Lorsomradee, S.; Lorsomradee, S. R.; Cromheecke, S.; de Hert, S. G.


    This study compared cardiac output measured with an arterial pressure-based cardiac output measurement system and a thermodilution cardiac output measurement system. We studied 36 patients undergoing cardiac surgery with cardiopulmonary bypass. Simultaneous arterial pressure-based and thermodilution

  7. Prospective Comparative Analysis of 4 Different Intraocular Pressure Measurement Techniques and Their Effects on Pressure Readings. (United States)

    Berk, Thomas A; Yang, Patrick T; Chan, Clara C


    To compare intraocular pressure (IOP) measurement using the Goldmann applanation tonometry (GAT) without fluorescein, with fluorescein strips, with fluorescein droplets, and IOP measurement with Tono-Pen Avia (TPA). This was a prospective comparative clinical analysis. It was performed in clinical practice. The study population consisted of 40 volunteer patients, 1 eye per patient. All patients who were 18 years and older having routine ophthalmological examination were eligible to participate. Active corneal abrasions and/or ulcers, previous glaucoma surgery, or prostheses interfering with GAT measurement were excluded. GAT IOP was measured first without fluorescein, then with fluorescein strip, then with fluorescein droplet, and finally with the TPA device. The main outcome measure was central corneal IOP. Mean±SD IOP measurements for GAT without fluorescein, with fluorescein strip, with fluorescein droplet, and for TPA groups were 12.65±3.01, 14.70±2.82, 15.78±2.64, and 16.33±3.08 mm Hg, respectively. Repeated-measures analysis of variance corrected with the Greenhouse-Geisser estimate ([Latin Small Letter Open E]=0.732) showed that measuring technique had a significant effect on IOP measurements (F2.20,85.59=34.66, Pmeasurement ranging from 5.89 mm Hg in the GAT with fluorescein strip versus droplet compared with 11.83 mm Hg in the GAT with fluorescein strip versus TPA comparison. IOP measurement technique significantly impacted the values obtained. The ophthalmologist should ensure consistent measurement technique to minimize variability when following patients.

  8. Strategies to reduce pitfalls in measuring blood pressure

    Directory of Open Access Journals (Sweden)

    Hamidreza Badeli


    Full Text Available Errors in blood pressure (BP measurement are common in the clinical practice. Inaccurate measurements of BP may lead to misdiagnosis and inappropriate treatment of hypertension. The preferred method of BP measurement in the clinical setting is auscultation, using the first and the fifth Korotkoff sounds. However, the use of mercury sphygmomanometer is declining. Automated oscillometric devices are an acceptable alternative method of BP measurements if the proper cuff size is used. Aneroid devices are suitable, but they require frequent calibration. There is increasing evidence that home readings predict cardiovascular events and are particularly useful for monitoring the effects of treatment. At 24 h ambulatory monitoring is also useful for diagnosing white-coat hypertension and resistance hypertension. There is increasing evidence that lack of nocturnal BP dipping during the night may be associated with increased cardiovascular event. This report attempts to address the need for accurate BP measurements in children and adolescents by reducing human and equipment errors and providing clinicians with the accurate measurement of BP, which is essential to classify individuals, to ascertain BP-related CV risks and to guide management.

  9. SI-traceable and dynamic reference gas mixtures for water vapour at polar and high troposphere atmospheric levels (United States)

    Guillevic, Myriam; Pascale, Céline; Mutter, Daniel; Wettstein, Sascha; Niederhauser, Bernhard


    In the framework of METAS' AtmoChem-ECV project, new facilities are currently being developed to generate reference gas mixtures for water vapour at concentrations measured in the high troposphere and polar regions, in the range 1-20 µmol/mol (ppm). The generation method is dynamic (the mixture is produced continuously over time) and SI-traceable (i.e. the amount of substance fraction in mole per mole is traceable to the definition of SI-units). The generation process is composed of three successive steps. The first step is to purify the matrix gas, nitrogen or synthetic air. Second, this matrix gas is spiked with the pure substance using a permeation technique: a permeation device contains a few grams of pure water in liquid form and loses it linearly over time by permeation through a membrane. In a third step, to reach the desired concentration, the first, high concentration mixture exiting the permeation chamber is then diluted with a chosen flow of matrix gas with one or two subsequent dilution steps. All flows are piloted by mass flow controllers. All parts in contact with the gas mixture are passivated using coated surfaces, to reduce adsorption/desorption processes as much as possible. The mixture can eventually be directly used to calibrate an analyser. The standard mixture produced by METAS' dynamic setup was injected into a chilled mirror from MBW Calibration AG, the designated institute for absolute humidity calibration in Switzerland. The used chilled mirror, model 373LX, is able to measure frost point and sample pressure and therefore calculate the water vapour concentration. This intercomparison of the two systems was performed in the range 4-18 ppm water vapour in synthetic air, at two different pressure levels, 1013.25 hPa and 2000 hPa. We present here METAS' dynamic setup, its uncertainty budget and the first results of the intercomparison with MBW's chilled mirror.

  10. Numerical Simulation of Pulsation Flow in the Vapour Channel of Short Low Temperature Heat Pipes at High Heat Loads (United States)

    Seryakov, A. V.; Konkin, A. V.


    The results of the numerical simulation of pulsations in the Laval-liked vapour channel of short low-temperature range heat pipes (HPs) are presented. The numerical results confirmed the experimentally obtained increase of the frequency of pulsations in the vapour channel of short HPs with increasing overheat of the porous evaporator relative to the boiling point of the working fluid. The occurrence of pressure pulsations inside the vapour channel in a short HPs is a complex phenomenon associated with the boiling beginning in the capillary-porous evaporator at high heat loads, and appearance the excess amount of vapour above it, leading to the increase in pressure P to a value at which the boiling point TB of the working fluid becomes higher than the evaporator temperature Tev. Vapour clot spreads through the vapour channel and condense, and then a rarefaction wave return from condenser in the evaporator, the boiling in which is resumed and the next cycle of the pulsations is repeated. Numerical simulation was performed using finite element method implemented in the commercial program ANSYS Multiphisics 14.5 in the two-dimensional setting of axis symmetric moist vapour flow with third kind boundary conditions.

  11. Effect of Liquid/Vapour Maldistribution on the Performance of Plate Heat Exchanger Evaporators

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Kærn, Martin Ryhl; Ommen, Torben Schmidt


    Plate heat exchangers are often applied as evaporators in industrial refrigeration and heat pump systems. In the design and modelling of such heat exchangers the flow and liquid/vapour distribution is often assumed to be ideal. However, maldistribution may occur and will cause each channel...... to behave differently due to the variation of the mass flux and vapour quality. To evaluate the effect of maldistribution on the performance of plate heat exchangers, a numerical model is developed in which the mass, momentum and energy balances are applied individually to each channel, including suitable...... correlations for heat transfer and pressure drop. The flow distribution on both the refrigerant and secondary side is determined based on equal pressure drop while the liquid/vapour distribution is imposed to the model. Results show that maldistribution may cause up to a 25 % reduction of the overall heat...

  12. Quantitative Thermochemical Measurements in High-Pressure Gaseous Combustion (United States)

    Kojima, Jun J.; Fischer, David G.


    We present our strategic experiment and thermochemical analyses on combustion flow using a subframe burst gating (SBG) Raman spectroscopy. This unconventional laser diagnostic technique has promising ability to enhance accuracy of the quantitative scalar measurements in a point-wise single-shot fashion. In the presentation, we briefly describe an experimental methodology that generates transferable calibration standard for the routine implementation of the diagnostics in hydrocarbon flames. The diagnostic technology was applied to simultaneous measurements of temperature and chemical species in a swirl-stabilized turbulent flame with gaseous methane fuel at elevated pressure (17 atm). Statistical analyses of the space-/time-resolved thermochemical data provide insights into the nature of the mixing process and it impact on the subsequent combustion process in the model combustor.

  13. Sound field separation with sound pressure and particle velocity measurements

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Jacobsen, Finn; Leclère, Quentin


    and the velocity in a single layer are proposed. The two methods use an equivalent source formulation with separate transfer matrices for the outgoing and incoming waves, so that the sound from the two sides of the array can be modeled independently. A weighting scheme is proposed to account for the distance......In conventional near-field acoustic holography (NAH) it is not possible to distinguish between sound from the two sides of the array, thus, it is a requirement that all the sources are confined to only one side and radiate into a free field. When this requirement cannot be fulfilled, sound field...... separation techniques make it possible to distinguish between outgoing and incoming waves from the two sides, and thus NAH can be applied. In this paper, a separation method based on the measurement of the particle velocity in two layers and another method based on the measurement of the pressure...

  14. Measurement of lying and standing blood pressure in hospital. (United States)

    O'Riordan, Shelagh; Vasilakis, Naomi; Hussain, Labib; Schoo, Rowena; Whitney, Julie; Windsor, Julie; Horton, Khim; Martin, Finbarr


    Measuring lying and standing blood pressure (BP) is an important clinical observation in older hospital inpatients. This is because a drop in BP on standing, known as orthostatic hypotension (OH) is common in older people and in acute illness and, therefore, in hospital patients. OH increases the risk of a fall in hospital. Simple measures such as changes in medication or rehydration can reduce this drop in BP and reduce the risk of falls. In a recent snapshot audit in England and Wales of 179 acute hospitals and 4,846 patients aged 65 years and over admitted with an acute illness, only 16% had a lying and standing BP recorded within 48 hours. A review of the literature showed that existing advice on how to measure and interpret lying and standing BP was often not appropriate for use on the ward with frail and unwell inpatients. An online survey of 275 clinicians' usual practice highlighted variation and the need for clarity and pragmatism. In the light of the survey findings, a clinical guide has been developed on when to measure lying and standing BP, how to measure it and what is considered a significant result. ©2012 RCN Publishing Company Ltd. All rights reserved. Not to be copied, transmitted or recorded in any way, in whole or part, without prior permission of the publishers.

  15. Measurements of intraperitoneal pressure and the development of a feedback control valve for regulating pressure during flexible transgastric surgery (NOTES). (United States)

    Bergström, Maria; Swain, Paul; Park, Per-Ola


    High intraabdominal pressures during laparoscopy (greater than 15 mm Hg) are dangerous. Pressures developed during translumenal endosurgery when using flexible endoscopes without feed-back regulation are unknown. To measure and control intraabdominal pressures during transgastric endosurgery. In a blinded study, intraabdominal pressures during unregulated transgastric cholecystectomy and tubal ligation were measured by using Veress needles in 5 pigs (group 1). The accessory channel valve of a double-channel gastroscope was modified to allow measurement and control of intraabdominal pressures with a laparoscopic insufflator. This was tested prospectively in another blinded study in 5 pigs (group 2) that underwent identical procedures to those in group 1, with independent Veress needle pressure measurements. This ethically approved study was performed in an experimental surgical operating theater. Transgastric cholecystectomy (n=4) and tubal resection (n=6). Intraabdominal pressure measurements during transgastric endosurgery, with and without feed-back control. The mean (standard deviation) number of pressure measurements per procedure greater than 20 mm Hg was 11+/-1.41 in group 1 and 0+/-0 in group 2 (PFeedback pressure regulation through a modified valve prevented overinflation.

  16. Development of vapour liquid equilibrium calculation methods for chemical engineering design


    Pokki, Juha-Pekka


    This thesis deals with the development of computational methods for vapour liquid equilibrium (VLE) and volumetric properties. The VLE in this thesis can be divided into the low- and medium-pressure VLE with an experimental part and into the high-pressure VLE with a modelling and simulation part. The volumetric properties in this thesis deal with the extension of the model for compressed liquid densities. At low-pressure VLE, the emphasis was on the optimisation of model parameters. Two a...

  17. Context-aware patient guidance during blood pressure self-measurement

    DEFF Research Database (Denmark)

    Sandager, Puk; Lindahl, Camilla; Schlütter, Jacob Mørup


    The importance of accurate measurement of blood pressure in the screening and management of hypertension during pregnancy is well established. Blood pressure levels can be measured manually by healthcare staff or by using a blood pressure self-measurement device, either at home or in the clinic...... the blood pressure self-measurement process. Preliminary results indicate that such active and context-aware guidance leads to more reliable measurements by inhibiting non-adherent patient behavior...

  18. Clinic blood pressure measurements and blood pressure load in the diagnosis of hypertension.


    Lee, D. R.; Sivakumaran, P.; Brown, R.


    We have retrospectively compared the blood pressure load derived from 24 hour ambulatory blood pressure monitoring in patients with all clinic blood pressure readings elevated with those with only some elevated pressures to establish whether clinic readings alone are good predictors of blood pressure status. Fifty-seven patients attending a district general hospital hypertension clinic who were not on anti-hypertensive treatment were selected. Between two and six clinic readings were taken ov...

  19. Comparison of aneroid and oscillometric blood pressure measurements in children. (United States)

    Eliasdottir, Sigridur B; Steinthorsdottir, Sandra D; Indridason, Olafur S; Palsson, Runolfur; Edvardsson, Vidar O


    Limited data exist on the comparison of blood pressure (BP) measurements using aneroid and oscillometric devices. The purpose of the study was to investigate the difference in BP obtained using oscillometric and aneroid BP monitors in 9- to 10-year-old children. A total of 979 children were divided into group O, which underwent two oscillometric BP readings followed by two aneroid readings, and group A, which had BP measured in the reverse order. No significant difference was found between the mean (±standard deviation) of the two systolic BP readings obtained using the oscillometric and aneroid devices (111.5±8.6 vs 111.3±8.1 mm Hg; P=.39), whereas the mean diastolic BP was lower with the oscillometric monitor (61.5±8.0 vs 64.5±6.8 mm Hg; P<.001). A significant downward trend in BP was observed with each consecutive measurement, and agreement between the two monitors was limited. Multiple BP measurements are, therefore, recommended before the diagnosis of elevated BP or hypertension is made with either method. ©2013 Wiley Periodicals, Inc.

  20. Reliable intraocular pressure measurement using automated radio-wave telemetry

    Directory of Open Access Journals (Sweden)

    Paschalis EI


    Full Text Available Eleftherios I Paschalis,* Fabiano Cade,* Samir Melki, Louis R Pasquale, Claes H Dohlman, Joseph B CiolinoMassachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, USA*These authors contributed equally to this workPurpose: To present an autonomous intraocular pressure (IOP measurement technique using a wireless implantable transducer (WIT and a motion sensor.Methods: The WIT optical aid was implanted within the ciliary sulcus of a normotensive rabbit eye after extracapsular clear lens extraction. An autonomous wireless data system (AWDS comprising of a WIT and an external antenna aided by a motion sensor provided continuous IOP readings. The sensitivity of the technique was determined by the ability to detect IOP changes resulting from the administration of latanoprost 0.005% or dorzolamide 2%, while the reliability was determined by the agreement between baseline and vehicle (saline IOP.Results: On average, 12 diurnal and 205 nocturnal IOP measurements were performed with latanoprost, and 26 diurnal and 205 nocturnal measurements with dorzolamide. No difference was found between mean baseline IOP (13.08±2.2 mmHg and mean vehicle IOP (13.27±2.1 mmHg (P=0.45, suggesting good measurement reliability. Both antiglaucoma medications caused significant IOP reduction compared to baseline; latanoprost reduced mean IOP by 10% (1.3±3.54 mmHg; P<0.001, and dorzolamide by 5% (0.62±2.22 mmHg; P<0.001. Use of latanoprost resulted in an overall twofold higher IOP reduction compared to dorzolamide (P<0.001. Repeatability was ±1.8 mmHg, assessed by the variability of consecutive IOP measurements performed in a short period of time (≤1 minute, during which the IOP is not expected to change.Conclusion: IOP measurements in conscious rabbits obtained without the need for human interactions using the AWDS are feasible and provide reproducible results.Keywords: IOP, pressure transducer, wireless, MEMS, implant, intraocular

  1. Vapours of US and EU Market Leader Electronic Cigarette Brands and Liquids Are Cytotoxic for Human Vascular Endothelial Cells. (United States)

    Putzhammer, Raphaela; Doppler, Christian; Jakschitz, Thomas; Heinz, Katharina; Förste, Juliane; Danzl, Katarina; Messner, Barbara; Bernhard, David


    The present study was conducted to provide toxicological data on e-cigarette vapours of different e-cigarette brands and liquids from systems viewed as leaders in the e-cigarette market and to compare e-cigarette vapour toxicity to the toxicity of conventional strong high-nicotine cigarette smoke. Using an adapted version of a previously constructed cigarette smoke constituent sampling device, we collected the hydrophilic fraction of e-cigarette vapour and exposed human umbilical vein endothelial cells (HUVECs) to the mixture of compounds present in the vapour of 4 different single-use e-cigarettes, 6 different liquid vapours produced by the same refillable e-cigarette, and one e-cigarette with an exchangeable liquid cartridge. After incubation of cells with various concentrations and for various periods of time we analysed cell death induction, proliferation rates, the occurrence of intra-cellular reactive oxygen species, cell morphology, and we also measured e-cigarette heating coil temperatures. Overall, conventional cigarette smoke extract showed the most severe impact on endothelial cells. However, some e-cigarette vapour extracts showed high cytotoxicity, inhibition of cell proliferation, and alterations in cell morphology, which were comparable to conventional high-nicotine cigarettes. The vapours generated from different liquids using the same e-cigarette show substantial differences, pointing to the liquids as an important source for toxicity. E-cigarette vapour-mediated induction of oxidative stress was significant in one out of the 11 analysed vapours. There is a high variability in the acute cytotoxicity of e-cigarette vapours depending on the liquid and on the e-cigarettes used. Some products showed toxic effects close to a conventional high-nicotine cigarette. Liquid nicotine, menthol content, and the formation of acute intracellular reactive oxygen species do not seem to be the central elements in e-cigarette vapour toxicity.

  2. Vapours of US and EU Market Leader Electronic Cigarette Brands and Liquids Are Cytotoxic for Human Vascular Endothelial Cells.

    Directory of Open Access Journals (Sweden)

    Raphaela Putzhammer

    Full Text Available The present study was conducted to provide toxicological data on e-cigarette vapours of different e-cigarette brands and liquids from systems viewed as leaders in the e-cigarette market and to compare e-cigarette vapour toxicity to the toxicity of conventional strong high-nicotine cigarette smoke. Using an adapted version of a previously constructed cigarette smoke constituent sampling device, we collected the hydrophilic fraction of e-cigarette vapour and exposed human umbilical vein endothelial cells (HUVECs to the mixture of compounds present in the vapour of 4 different single-use e-cigarettes, 6 different liquid vapours produced by the same refillable e-cigarette, and one e-cigarette with an exchangeable liquid cartridge. After incubation of cells with various concentrations and for various periods of time we analysed cell death induction, proliferation rates, the occurrence of intra-cellular reactive oxygen species, cell morphology, and we also measured e-cigarette heating coil temperatures. Overall, conventional cigarette smoke extract showed the most severe impact on endothelial cells. However, some e-cigarette vapour extracts showed high cytotoxicity, inhibition of cell proliferation, and alterations in cell morphology, which were comparable to conventional high-nicotine cigarettes. The vapours generated from different liquids using the same e-cigarette show substantial differences, pointing to the liquids as an important source for toxicity. E-cigarette vapour-mediated induction of oxidative stress was significant in one out of the 11 analysed vapours. There is a high variability in the acute cytotoxicity of e-cigarette vapours depending on the liquid and on the e-cigarettes used. Some products showed toxic effects close to a conventional high-nicotine cigarette. Liquid nicotine, menthol content, and the formation of acute intracellular reactive oxygen species do not seem to be the central elements in e-cigarette vapour toxicity.

  3. Seeking a blood pressure-independent measure of vascular properties. (United States)

    Steppan, Jochen; Sikka, Gautam; Hori, Daijiro; Nyhan, Daniel; Berkowitz, Dan E; Gottschalk, Allan; Barodka, Viachaslau


    Pulse wave velocity (PWV) and pulse pressure (PP) are blood pressure (BP)-dependent surrogates for vascular stiffness. Considering that there are no clinically useful markers for arterial stiffness that are BP-independent, our objective was to identify novel indices of arterial stiffness and compare them with previously described markers. PWV and PP were measured in young and old male Fisher rats and in young and old male spontaneously hypertensive rats (SHR) over a wide range of BPs. The BP dependence of these and several other indices of vascular stiffness were evaluated. An index incorporating PWV and PP was also constructed. Both PWV and PP increase in a non-linear manner with rising BP for both strains of animals (Fisher and SHRs). Age markedly changes the relationship between PWV or PP and BP. The previously described Ambulatory Arterial Stiffness Index (AASI) was able to differentiate between young and old vasculature, whereas the Cardio-Ankle Vascular Index (CAVI) did not reliably differentiate between the two. The novel Arterial Stiffness Index (ASI) differentiated stiffer from more compliant vasculature. Considering the limitations of the currently available indices of arterial stiffness, we propose a novel index of intrinsic arterial stiffness, the ASI, which is robust over a range of BPs and allows one to distinguish between compliant and stiff vasculature in both Fisher rats and SHRs. Further studies are necessary to validate this index in other settings.

  4. Stress Rupture Life Reliability Measures for Composite Overwrapped Pressure Vessels (United States)

    Murthy, Pappu L. N.; Thesken, John C.; Phoenix, S. Leigh; Grimes-Ledesma, Lorie


    Composite Overwrapped Pressure Vessels (COPVs) are often used for storing pressurant gases onboard spacecraft. Kevlar (DuPont), glass, carbon and other more recent fibers have all been used as overwraps. Due to the fact that overwraps are subjected to sustained loads for an extended period during a mission, stress rupture failure is a major concern. It is therefore important to ascertain the reliability of these vessels by analysis, since the testing of each flight design cannot be completed on a practical time scale. The present paper examines specifically a Weibull statistics based stress rupture model and considers the various uncertainties associated with the model parameters. The paper also examines several reliability estimate measures that would be of use for the purpose of recertification and for qualifying flight worthiness of these vessels. Specifically, deterministic values for a point estimate, mean estimate and 90/95 percent confidence estimates of the reliability are all examined for a typical flight quality vessel under constant stress. The mean and the 90/95 percent confidence estimates are computed using Monte-Carlo simulation techniques by assuming distribution statistics of model parameters based also on simulation and on the available data, especially the sample sizes represented in the data. The data for the stress rupture model are obtained from the Lawrence Livermore National Laboratories (LLNL) stress rupture testing program, carried out for the past 35 years. Deterministic as well as probabilistic sensitivities are examined.


    Energy Technology Data Exchange (ETDEWEB)

    Vinayak N. Kabadi


    The Vapor Liquid Equilibrium measurement setup of this work was first established several years ago. It is a flow type high temperature high pressure apparatus which was designed to operate below 500 C temperature and 2000 psia pressure. Compared with the static method, this method has three major advantages: the first is that large quantity of sample can be obtained from the system without disturbing the equilibrium state which was established before; the second is that the residence time of the sample in the equilibrium cell is greatly reduced, thus decomposition or contamination of the sample can be effectively prevented; the third is that the flow system allows the sample to degas as it heats up since any non condensable gas will exit in the vapor stream, accumulate in the vapor condenser, and not be recirculated. The first few runs were made with Quinoline-Tetralin system, the results were fairly in agreement with the literature data . The former graduate student Amad used the same apparatus acquired the Benzene-Ethylbenzene system VLE data. This work used basically the same setup (several modifications had been made) to get the VLE data of Ethylbenzene-Quinoline system.

  6. Comparison of tanker drivers' occupational exposures before and after the installation of a vapour recovery system. (United States)

    Saarinen, L; Hakkola, M; Kangas, J


    The purpose of this study was to compare tanker drivers' occupational exposure level before and after the installation of vapour recovery facilities at 14 service stations. Road tanker drivers are exposed when handling volatile petrol liquid in bulk in the distribution chain. The drivers' exposure was studied during the unloading operation as the bulk petrol flowed into underground storage tanks, displacing vapours in the tank space and causing emission to the environment and the drivers' work area. The exposures were measured again when the dual point Stage I vapour recovery systems were installed for recycling vapours. Short-term measurements were carried out in the drivers' breathing zones by drawing polluted air through a charcoal tube during unloading. The samples were analysed in the laboratory by gas chromatography for C3-C11 aliphatic hydrocarbons, tert-butyl methyl ether (MTBE), tert-amyl methyl ether (MTAE), benzene, toluene and xylene. The road tanker loads delivered consisted of oxygenated and reformulated petrol (E95 and E98 brands), which contained on average 13% oxygenates. Before the installation of the vapour recovery system, the geometric mean (GM) concentration of aliphatic hydrocarbons was 65 mg m-3 (range 6-645 mg m-3) in the drivers' breathing zones. After the installation at the same service stations, the corresponding exposure level was 8.3 mg m-3 (range tankers without and with vapour recovery were statistically significant (p < 0.05).

  7. Line-shape study of water vapour by tunable diode laser spectrometer in the 822 832 nm wavelength region (United States)

    Ray, A.; Bandyopadhyay, A.; Ray, B.; Biswas, D.; Ghosh, P. N.


    A near-infrared tunable diode laser absorption spectrometer is set up to measure the air-induced broadening coefficients and the line-strength parameters of water-vapour overtone transitions within the (2,1,1)←(0,0,0) band in the 822 832 nm wavelength region. A Hitachi HL8311 E double hetero-junction structure diode laser is used as a probe. The diode laser controller is home-built and stable within ±10 μA and ±10 mK, respectively. The laser-head mount has a simple design and provides easy access whenever changing of the laser head is required. The diode laser emission wavelength is thermally tuned between 50 °C and 12 °C. Thermal tuning of the diode laser emission wavelength is used to reveal the mode structure of the diode laser and to probe the overtone-band transitions of water vapour within its operating wavelength range. Current tuning of the diode laser is used at a fixed laser temperature to study the transitions one at a time. A balanced detector is used to improve the S/N ratio of the spectrum. A phase sensitive detection technique is followed to obtain the first-derivative spectra of the overtone transitions. The first-derivative spectra have been recorded at different air pressures inside the sample cell while the water-vapour pressure is kept fixed. The first-derivative spectrum is numerically integrated to obtain the original line shape. The original line shape is fitted with a Voigt profile by using a nonlinear least-squares fit program to extract the air-broadening coefficient and the line-strength parameter. The data obtained in our work is compared with the results of the HITRAN database.

  8. The Correlation between Systolic Blood Pressure Measured by Return to Flow Versus Systolic Blood Pressure Measured by Arterial Catheter in the Adult Anesthetized Patient. (United States)


    36 The Development of the Blood Pressure Cuff ....... 38 Pulse Detection ...................................39 The Development of the Oscillometric ...48 tq Measurement Tools .................................50 Oscillometric Blood Pressure Monitor...24• 6. Chart Recording of Oscillometric Automatic Blood Pressure Monitor Determination Cycle ................ 51 7. Chart Recording of Sys Stat

  9. In situ viscosity measurements of albite melt under high pressure

    CERN Document Server

    Funakoshi, K I; Terasaki, H


    The viscosities of albite (NaAlSi sub 3 O sub 8) melt under high pressures have been measured using an x-ray radiography falling sphere method with synchrotron radiation. This method has enabled us to determine the precise sinking velocity directly. Recent experiments of albite melt showed the presence of a viscosity minimum around 5 GPa (Poe et al 1997 Science 276 1245, Mori et al 2000 Earth Planet. Sci. Lett. 175 87). We present the results for albite melt up to 5.2 GPa at 1600 and 1700 deg. C. The viscosity minimum is clearly observed to be around 4.5 GPa, and it might be explained not by the change of the compression mechanism in albite melt but by change of the phase itself.

  10. Methods of Blood Pressure Measurement in the ICU*


    Talmor, Daniel; Malhotra, Atul; Lehman, Li-Wei; Saeed, Mohammed; Mark, Roger G


    OBJECTIVE:: Minimal clinical research has investigated the significance of different blood pressure monitoring techniques in the ICU and whether systolic vs. mean blood pressures should be targeted in therapeutic protocols and in defining clinical study cohorts. The objectives of this study are to compare real-world invasive arterial blood pressure with noninvasive blood pressure, and to determine if differences between the two techniques have clinical implications. DESIGN:: We conducted a re...

  11. Airborne hygrometer calibration inter-comparison against a metrological water vapour standard (United States)

    Smorgon, Denis; Boese, Norbert; Ebert, Volker


    of PTB and a validated, two-pressure generator acting as a highly stable and reproducible source of water vapour. The aim of AV2-B was to perform an absolute, metrological comparison of the field instruments/calibration infrastructures to the metrological humidity scale, and to collect essential information about methods and procedures used by the atmospheric community for instrument calibration and validation, in order to investigate e.g. the necessity and possible comparability advantage by a standardized calibration procedure. The work will give an overview over the concept of the AV2-B inter-comparison, the various general measurement and calibration principles, and discuss the outcome and consequences of the comparison effort. The AQUAVIT effort is linked to the EMRP project METEOMET (ENV07) and partially supported by the EMRP and ENV07. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. [1] H. Saathoff, C. Schiller, V. Ebert, D. W. Fahey, R.-S. Gao, O. Möhler, and the aquavit team, The AQUAVIT formal intercomparison of atmospheric water measurement methods, 5th General Assembly of the European Geosciences Union, 13-18 April 2008, Vienna, Austria Keywords: humidity, water vapour, inter-comparison, airborne instruments.

  12. Measurement of the change in the number of ultrafine bubbles through pressurization (United States)

    Tuziuti, T.; Yasui, K.; Kanematsu, Wataru


    The present study deals with, for the first time, a measurement of the number of bubbles of submicron in size before and after pressurization. Measurement of ultrafine bubbles of submicron size was conducted and it was clarified that greater number of submicron sized bubbles existed before the pressurization in comparison with that after the pressurization. The application of high pressure of gas for its dissolution into water and the ambient-pressure reduction has a possibility to increase the number of ultrafine bubbles.

  13. Immunological disorders in men exposed to metallic mercury vapour. A review. (United States)

    Moszczyński, P


    The awareness of the effects of metallic mercury vapour on the human immune system has increased only in the last decade. The regulatory guidelines relating to testing for immunotoxicity of metals are not standardized so far. A full understanding of the relevance of the tests to man is still incomplete. Immunotoxicity investigation of metals in rodents, with subsequent extrapolation to man, forms the basis of human risk assessment. Human contact with mercury vapour is mainly in chloralkali plants and in factories producing controlling and measuring devices. When the immune system acts as a target of xenobiotic insults, the result can be a decreased resistance to infection, cancers, or immune disregulation that can induce the development of allergy, or autoimmunity (Fig. 1). This article reviews literature data and our studies concerning the immunotoxicity of metallic mercury vapour. A number of data shows that mercury exerts a suppressing effect but another data suggest stimulating effects on the human immune system. The results of immunological monitoring of individuals exposed to mercury vapour were either positive or negative as well as borderline and uncertain as to the influence of mercury vapour on human immune system. The positive data had no influence on the resistance of workers to infections and neoplasms. Skin and mucosa hypersensitivity to metallic mercury is rare. No positive report that mercury vapour could be carcinogenic in man has appeared up to now.

  14. Liquid crystalline fiber optic colorimeter for hydrostatic pressure measurement (United States)

    Wolinski, Tomasz R.; Bajdecki, Waldemar K.; Domanski, Andrzej W.; Karpierz, Miroslaw A.; Konopka, Witold; Nasilowski, T.; Sierakowski, Marek W.; Swillo, Marcin; Dabrowski, Roman S.; Nowinowski-Kruszelnicki, Edward; Wasowski, Janusz


    This paper presents results of tests performed on a fiber optic system of liquid crystalline transducer for hydrostatic pressure monitoring based on properties of colorimetry. The system employs pressure-induced deformations occurring in liquid crystalline (LC) cells configured in a homogeneous Frederiks geometry. The sensor is compared of a round LC cell placed inside a specially designed pressure chamber. As a light source we used a typical diode operating at red wavelength and modulated using standard techniques. The pressure transducer was connected to a computer with a specially designed interface built on the bas of advanced ADAM modules. Results indicate that the system offers high response to pressure with reduced temperature sensitivity and, depending on the LC cell used, can be adjusted for monitoring of low hydrostatic pressures up to 6 MPa. These studies have demonstrated the feasibility of fiber optic liquid crystal colorimeter for hydrostatic pressure sensing specially dedicated to pipe- lines, mining instrumentation, and process-control technologies.

  15. Urethral pressure reflectometry. A method for simultaneous measurements of pressure and cross-sectional area in the female urethra

    DEFF Research Database (Denmark)

    Klarskov, Niels


    A novel technique for simultaneous measurements of pressure and cross-sectional area (CA) in the female urethra, denoted Urethral Pressure Reflectometry (UPR), was devised. A very thin and highly flexible polyurethane-bag was placed in the urethra. A pump applied increasing and decreasing pressures...... to the polyurethane-bag and thereby opened and closed the urethra. Sound waves were continually sent into the polyurethane-bag and the cross-sectional area (CA) of the bag (urethra) could be measured from the reflections with Acoustic Reflectometry. The CA of the bag was measured for each mm of the bag and 10 times...

  16. Comparison of automated oscillometric versus auscultatory blood pressure measurement. (United States)

    Landgraf, Johanna; Wishner, Stanley H; Kloner, Robert A


    Most clinical offices rely on automated oscillometric devices to measure blood pressure (BP), but the accuracy of this technique versus auscultatory determination using a mercury manometer is controversial. To assess the accuracy of automated oscillometric readings, BP was measured from the same site and cuff, in 337 consecutive patients seen in a routine cardiology office, using a simultaneous connection to an automated oscillometric and a mercury manometer technique. The mean systolic BP (133 +/- 20 mm Hg) and diastolic BP (72 +/- 11 mm Hg) were significantly greater using the mercury manometer than the automated oscillometric technique (systolic 131 +/- 18 and diastolic 70 +/- 12 mm Hg, p oscillometric and greater mercury manometer) in systolic BP were seen in 22% of all patients. Discrepancies in diastolic BP were seen in 20% of all patients. The mean of the discrepancy between the 2 techniques was 1.95 +/- 5 mm Hg (range 1 to 26) for systolic BP and 1.3 +/- 4 mm Hg (range 1 to 25) for diastolic BP. The discrepancies were greater in patients >65 years. In conclusion, the mercury manometer technique resulted in consistently greater BP values than oscillometric devices. These findings have important clinical implications, including the concept that patients whose BP appears to be under control using the oscillometric technique might not be at their goal BP and might have been undertreated. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  17. Thermal diffusion of water vapour in porous materials: fact or fiction?

    DEFF Research Database (Denmark)

    Janssen, Hans


    The reliable evaluation of moisture transfer in porous materials is essential in many engineering applications, among which building science. One key aspect is a correct description of moisture flow phenomena and their transport potentials. While different issues can be debated in that respect...... its negligible magnitude. It can in conclusion be stated that thermal diffusion is of no importance for building science applications, leaving vapour pressure as the sole significant transport potential for the diffusion of water vapour in porous materials. (C) 2010 Elsevier Ltd. All rights reserved....

  18. Increase of Short-Term Heart Rate Variability Induced by Blood Pressure Measurements during Ambulatory Blood Pressure Monitoring

    Directory of Open Access Journals (Sweden)

    Attila Frigy


    Full Text Available Objective. The possible effect of blood pressure measurements per se on heart rate variability (HRV was studied in the setting of concomitant ambulatory blood pressure monitoring (ABPM and Holter ECG monitoring (HM. Methods. In 25 hypertensive patients (14 women and 11 men, mean age: 58.1 years, 24-hour combined ABPM and HM were performed. For every blood pressure measurement, 2-minute ECG segments (before, during, and after measurement were analyzed to obtain time domain parameters of HRV: SDNN and rMSSD. Mean of normal RR intervals (MNN, SDNN/MNN, and rMSSD/MNN were calculated, too. Parameter variations related to blood pressure measurements were analyzed using one-way ANOVA with multiple comparisons. Results. 2281 measurements (1518 during the day and 763 during the night were included in the analysis. Both SDNN and SDNN/MNN had a constant (the same for 24-hour, daytime, and nighttime values and significant change related to blood pressure measurements: an increase during measurements and a decrease after them (p<0.01 for any variation. Conclusion. In the setting of combined ABPM and HM, the blood pressure measurement itself produces an increase in short-term heart rate variability. Clarifying the physiological basis and the possible clinical value of this phenomenon needs further studies.

  19. Correlation of Blood Pressure Variability as Measured By Clinic, Self-measurement at Home, and Ambulatory Blood Pressure Monitoring. (United States)

    Abellán-Huerta, José; Prieto-Valiente, Luis; Montoro-García, Silvia; Abellán-Alemán, José; Soria-Arcos, Federico


    Blood pressure variability (BPV) has been postulated as a potential predictor of cardiovascular outcomes. No agreement exists as to which measurement method is best for BPV estimation. We attempt to assess the correlation between BPV obtained at the doctor's office, self-measurement at home (SMBP) and ambulatory BP monitoring (ABPM). Eight weekly clinic BP measurements, 2 SMBP series, and 1 24-hour ABPM recording were carried out in a sample of treated hypertensive patients. BPV was calculated using the SD, the "coefficient of variation" and the "average real variability." Determinants of short-, mid-, and long-term BPV (within each measurement method) were also calculated. The different BPV determinants were correlated "intramethod" and "intermethod" by linear regression test. For the 104 patients (66.5 ± 7.7 years, 58.7% males), the ABPM BPV (SD, systolic/diastolic: 14.5 ± 3.1/9.8 ± 2.5 mm Hg) was higher than the SMBP (12.2 ± 9.8/7.4 ± 5.8 mm Hg; P < 0.001) and clinic BPV (10 ± 8.9/5.9 ± 4.9 mm Hg; P = 0.001). The main BPV correlation between methods was weak, with a maximum R2 = 0.17 (P < 0.001) between clinic and SMBP systolic BPV. The "intramethod" correlation of BPV yielded a maximum R2 = 0.21 (P < 0.001) between morning diastolic SMBP intershift/intermeans variability. The "intermethod" correlation of short-, mid-, and long-term BPV determinants was weak (maximum R2 = 0.22, P < 0.001, between clinic intraday variability/SMBP morning intershift variability). The "intramethod" and "intermethod" correlation between BPV determinants was weak or nonexistent, even when comparing determinants reflecting the same type of temporal BPV. Our data suggest that BPV reflects a heterogeneous phenomenon that strongly depends on the estimation method and the time period evaluated.

  20. Water vapour loss threshold and induction of cholinergic urticaria. (United States)

    Tupker, R A; Doeglas, H M


    A patient is described with cholinergic urticaria (CU) in whom the symptoms could be provoked by gustatory stimuli. The aim of this study was to investigate whether there is a threshold of sweating (monitored by skin water vapour loss (SVL) measurements) at which CU can be provoked. Provocations with lemon and sal-ammoniac liquorice induced transient sweating differing both in degree and duration. Only 'doubly salted' liquorice, which caused the most intense sweat response, resulted in urticarial lesions. This findings suggest a threshold dependency for the induction of CU. SVL measurement may be a useful method for the evaluation of sweating tests in CU patients.

  1. Measuring the level of agreement between directly measured blood pressure and pressure readings obtained with a veterinary-specific oscillometric unit in anesthetized dogs. (United States)

    Acierno, Mark J; Fauth, Erika; Mitchell, Mark A; da Cunha, Anderson


    To determine if an oscillometric device optimized for use in dogs produces systolic, diastolic, and mean arterial pressures (MAPs) measurements that are in good agreement with directly obtained pressures Prospective study. University teaching hospital. Twenty-one dogs under general anesthesia for surgical procedures. A 20-Ga catheter was placed into the dorsal pedal artery and systolic, diastolic, and MAPs were directly measured using a validated blood pressure measurement system. Indirect blood pressure measurements were collected using a widely available veterinary oscillometric blood pressure unit. Results obtained by the 2 methods were then compared. Agreement between the directly and indirectly measured pressure demonstrated a bias of 9.9 mm Hg and limits of agreement (LOA) 73.7 to -53.9, a bias of -8.9 mm Hg and LOA 23.3 to -41.2, and a bias of -6.3 mm Hg and LOA 28.2 to -40.8 for systolic, diastolic, and MAP, respectively. There was poor agreement between the direct and indirect measured blood pressure measurement systems. Therefore, use of the oscillometric blood pressure unit evaluated in this study for monitoring patients under anesthesia cannot be recommended at this time. © Veterinary Emergency and Critical Care Society 2013.

  2. Virucidal efficacy of hydrogen peroxide vapour disinfection. (United States)

    Tuladhar, E; Terpstra, P; Koopmans, M; Duizer, E


    Viral contamination of surfaces is thought to be important in transmission. Chemical disinfection can be an effective means of intervention, but little is known about the virucidal efficacy of hydrogen peroxide vapour (HPV) against enteric and respiratory viruses. To measure the virucidal efficacy of HPV against respiratory and enteric viruses on materials representing those found in institutions and homes. Poliovirus, human norovirus genogroup II.4 (GII.4), murine norovirus 1, rotavirus, adenovirus and influenza A (H1N1) virus dried on to stainless steel, framing panel and gauze carriers were exposed to HPV 127 ppm for 1h at room temperature in an isolator. Poliovirus was also exposed to HPV at different locations in a room. The virucidal effect was measured by comparing recoverable viral titres against unexposed controls. Polymerase chain reaction was used to evaluate the effect of HPV on viral genome reduction. HPV disinfection resulted in complete inactivation of all viruses tested, characterized by >4 log(10) reduction in infectious particles for poliovirus, rotavirus, adenovirus and murine norovirus on stainless steel and framing panel carriers, and >2 log(10) reduction for influenza A virus on stainless steel and framing panel carriers, and for all viruses on gauze carriers. Complete inactivation of poliovirus was demonstrated at several locations in the room. Reductions in viral genomes were minimal on framing panel and gauze carriers but significant on stainless steel carriers; human norovirus GII.4 genome was most resistant to HPV treatment. HPV could be an effective virucidal against enteric and respiratory viruses contaminating in-house environments. Copyright © 2011 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  3. Measurement of vacuum pressure with a magneto-optical trap: A pressure-rise method. (United States)

    Moore, Rowan W G; Lee, Lucie A; Findlay, Elizabeth A; Torralbo-Campo, Lara; Bruce, Graham D; Cassettari, Donatella


    The lifetime of an atom trap is often limited by the presence of residual background gases in the vacuum chamber. This leads to the lifetime being inversely proportional to the pressure. Here, we use this dependence to estimate the pressure and to obtain pressure rate-of-rise curves, which are commonly used in vacuum science to evaluate the performance of a system. We observe different rates of pressure increase in response to different levels of outgassing in our system. Therefore, we suggest that this is a sensitive method which will find useful applications in cold atom systems, in particular, where the inclusion of a standard vacuum gauge is impractical.

  4. Grip pressure measurements during activities of daily life (United States)

    Sanford, Joe; Young, Carolyn; Popa, Dan; Bugnariu, Nicoleta; Patterson, Rita


    Research has expanded human-machine communication methods past direct programming and standard hand- held joystick control. Individual force sensors have been used as a simple means of providing environmental information to a robot and research has shown that more advanced sensitive skins can be viable input devices. These touch sensitive surfaces allow for additional modes of interaction between machines in open, undefined environments. These interactions include object detection for navigation and safety but can also be used for recognition of users command gestures by their machine partner. Key to successful implementation of these gestures is the understanding of varied strategies used for communication and interaction and the development of performance limits. Data of dominant hand grip forces was collected using a Tekscan Grip VersaTek Pressure Measurement System during opening of a door. Analysis of data from 10 male and female subjects is presented. The results of qualitative and quantitative analysis of these data show variability in hand configurations between users. Average data over the cohort is reported. These data will be used in future work to provide human metrology constraints and limits for use in simulation and design of new, physical human-robot interaction systems.

  5. Effect of peripheral edema on oscillometric blood pressure measurement. (United States)

    Ghaffari, Shamsi; Malaki, Majid; Rezaeifar, Afshin; Abdollahi Fakhim, Shahin


    Blood pressure (BP) measurement is essential for epidemiological studies and clinical decisions. It seems that tissue characteristics can affect BP results and we try to find edema effect on BP results taken by different methods. BP of 55 children before open heart surgery were measured and compared according to three methods: Arterial as standard and reference, oscillometric and auscultatory methods. Peripheral edema as a tissue characteristic was defined in higher than +2 as marked edema and in equal or lower than +2 as no edema. data was expressed as Mean and 95% of confidence interval (CI 95%). Comparison of two groups was performed by T independent test and of more than two groups by ANOVA test. Mann-Whitney U and paired T-test were used for serially comparisons of changes. P less than 0.05 was considered significant. Fifty five children aged 29.4±3.9 months were divided into two groups: 10 children with peripheral edema beyond +2 and 45 cases without edema. Oscillometric method overestimated systolic BP and the Mean (CI 95%) difference of oscillometric to arterial was 4.8 (8/-1, P=0.02) in edematous and 4.2 (7/1, p=0.004) in non edematous. Oscillometric method underestimated diastolic BP as -9 (-1.8/-16.5, P=0.03) in edematous group and 2.6 (-0.7/+5, P= 0.2) in non edematous compared to arterial method. Oscillometric device standards cannot cover all specific clinical conditions. It underestimates diastolic BP significantly in edematous children, which was 9.2 mmHg in average beyond the acceptable standards.

  6. Anthropometric measures can better predict high blood pressure in adolescents. (United States)

    Papalia, Teresa; Greco, Rosita; Lofaro, Danilo; Mollica, Agata; Roberti, Rita; Bonofiglio, Renzo


    Among children, obesity and overweight may be predictors of cardiovascular (CV) risk. The purpose of this study was to examine whether body mass index (BMI), waist circumference (WC) and waist to height ratio (WHtR) were related to blood pressure (BP) among healthy southern Italian students enrolled in 3 different secondary schools. Weight, height, BP and WC were measured; BMI and WHtR were calculated for 872 Italian students. Based on percentiles of BMI, the subjects were classified as underweight, normal weight, overweight or obese. Systolic BP or diastolic BP >95th percentile were considered as high BP values (according to the 2004 guidelines of the US National Heart, Lung, and Blood Institute). Central obesity was defined as WC >75th percentile or WHtR =0.5. Of the students, 8.7% were obese, 29% with WC >75th percentile and 29.5% with WHtR >0.5, while 4.6% showed high BP. Logistic regression showed a strong correlation between BMI and high BP (odds ratio [OR] = 1.030, p<0.0001), between WC and high BP (OR = 1.029, p<0.0001). Also WHtR (OR = 3.403, p<0.0001) was shown to be a predictor of high BP. In the male group, all of the variables considered showed a good capability to predict high BP, while in the females, only BMI (OR = 1.019, p<0.05) and WHtR (OR = 2.685, p<0.05) were associated with high BP. In this study, we found a different correlation between BMI, WC and BP in the 2 subgroups: males and females. Only WHtR showed a significant ability to predict high BP in both groups. WHtR might represent an easily measurable anthropometric index and a better predictor of CV risk in adolescents.

  7. Prehospital endotracheal intubation; need for routine cuff pressure measurement?

    NARCIS (Netherlands)

    Peters, J.H.; Hoogerwerf, N.


    In endotracheal intubation, a secured airway includes an insufflated cuff distal to the vocal cords. High cuff pressures may lead to major complications occurring after a short period of time. Cuff pressures are not routinely checked after intubation in the prehospital setting, dealing with a

  8. Reliability of blood pressure measurement and cardiovascular risk prediction

    NARCIS (Netherlands)

    van der Hoeven, N.V.


    High blood pressure is one of the leading risk factors for cardiovascular disease, but difficult to reliably assess because there are many factors which can influence blood pressure including stress, exercise or illness. The first part of this thesis focuses on possible ways to improve the

  9. Central venous pulse pressure analysis using an R-synchronized pressure measurement system. (United States)

    Fujita, Yoshihisa; Hayashi, Daisuke; Wada, Shinya; Yoshioka, Naoki; Yasukawa, Takeshi; Pestel, Gunther


    The information derived from central venous catheters is underused. We developed an EKG-R synchronization and averaging system to obtained distinct CVP waveforms and analyzed components of these. Twenty-five paralyzed surgical patients undergoing CVP monitoring under mechanical ventilation were studied. CVP and EKG signals were analyzed employing our system, the mean CVP and CVP at end-diastole during expiration were compared, and CVP waveform components were measured using this system. CVP waveforms were clearly visualized in all patients. They showed the a peak to be 1.8+/- 0.7 mmHg, which was the highest of three peaks, and the x trough to be lower than the y trough (-1.6+/- 0.7 mmHg and -0.9+/- 0.5 mmHg, respectively), with a mean pulse pressure of 3.4 mmHg. The difference between the mean CVP and CVP at end-diastole during expiration was 0.58+/- 0.81 mmHg. The mean CVP can be used as an index of right ventricular preload in patients under mechanical ventilation with regular sinus rhythm. Our newly developed system is useful for clinical monitoring and for education in circulatory physiology.

  10. Pyramidal Traceability Hierarchy for Pressure Measurements and Calibrations at NIS- Egypt

    Directory of Open Access Journals (Sweden)



    Full Text Available Pressure balances are excellent standards for measuring pressure with acceptable uncertainty and they are widely used at the primary pressure laboratories in the world. This study aims to study the propagation of uncertainty from primary standard piston cylinder assembly (PCA up to 500 MPa. The hierarchy of pressure measurements at NIS is based on using large effective area PCA in defining the pressure of 1 MPa. Characterization of primary standard PCA is presented transferring the obtained results to other level pressure standard described. Uncertainty calculation method at each level was studied. Propagation of uncertainty from primary standards through national standards to digital pressure gauges, digital pressure calibrators, pressure sensors and pressure transducers were investigated. Study of the effect of each variable on the uncertainty calculation was discussed.

  11. A comparison of blood pressure measurements in newborns.

    LENUS (Irish Health Repository)

    O'Shea, Joyce


    Blood pressure monitoring is an essential component of neonatal intensive care. We compared invasive and noninvasive (Dinamap, Marquette, and Dash) recordings in newborns and also noninvasive values obtained from upper and lower limbs. Infants\\' blood pressure was recorded every 6 hours for 72 hours using three noninvasive devices and compared with invasive readings taken simultaneously. Twenty-five babies were enrolled in the study, with birth weights of 560 to 4500 g and gestation 24 + 1 to 40 + 5 weeks. Three hundred thirty-two recordings were obtained. Comparison between invasive and noninvasive readings revealed that all three noninvasive monitors overread mean blood pressure. There was no significant difference between the cuff recordings obtained from the upper or lower limbs. All three noninvasive devices overestimated mean blood pressure values compared with invasive monitoring. Clinicians may be falsely reassured by noninvasive monitoring. Mean blood pressure values obtained from the upper and lower limb are similar.

  12. Continuous urethral pressure measurements; measurement techniques; pressure variations; clinical interpretations; and clinical relevance. A Systematic Literature Analysis. (United States)

    Kummeling, Maxime T M; Rosier, Peter F W M; Elzevier, Henk W; Groenendijk, Pieter M


    The clinical relevance of urethral pressure variations (UPV) in the pathophysiology of over active bladder syndrome (OAB) has remained controversial to date. Some studies report an association with OAB and/or detrusor over activity (DO). Recently the International Consultation on Incontinence-Research Society recommended new clinical research to be performed on this subject. We provide a systematic review of the literature to specify this recommendation. Literature search was performed in PubMed, Embase, Web of Science, Cochrane, Central, Cinahl, Academic Science Premier, Science Direct, and Wiley Online using a sensitive search string combination. All authors independently reviewed and scored full text papers and consensus about methodological quality was obtained according to Oxford Level of Evidence (LoE). Four hundred eighty seven abstracts were screened, 25 papers met all predefined inclusion selection criteria. Incidence figures of UPV varied between 2% and 95%. Studies are of poor methodological quality with Oxford LoE scores of 3B and 4. Measurement methods and techniques show a large variety. The above mentioned association of DO/OAB with UPV is however frequently reported. There exists a phenomenon of UPV, apart from DO, which may be a separate entity within OAB syndrome. Large variation in measurement techniques and patient populations hinders fundamental research as well as clinical progress. Clinical relevance of UPV and consequences for treatment therefore are yet to be established. Future prospective research with well-defined patient population and standardised urodynamic measurement techniques is needed. Results of standardized and objective evaluations should be compared to clinical signs and symptoms by validated questionnaires. Neurourol. Urodynam. 36:51-56, 2017. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  13. Developments in vapour cloud explosion blast modeling

    NARCIS (Netherlands)

    Mercx, W.P.M.; Berg, A.C. van den; Hayhurst, C.J.; Robertson, N.J.; Moran, K.C.


    TNT Equivalency methods are widely used for vapour cloud explosion blast modeling. Presently, however, other types of models are available which do not have the fundamental objections TNT Equivalency models have. TNO Multi-Energy method is increasingly accepted as a more reasonable alternative to be

  14. Measurement of Intraocular Pressure by Patients With Glaucoma. (United States)

    Pronin, Savva; Brown, Lyndsay; Megaw, Roly; Tatham, Andrew J


    The ability of patients to measure their own intraocular pressure (IOP) would allow more frequent measurements and better appreciation of peak IOP and IOP fluctuation. To examine whether patients with glaucoma can perform self-tonometry using a rebound tonometer and examine patient acceptability. An observational study in which IOP was assessed using Goldmann applanation tonometry and a rebound tonometer. Consecutive patients were provided with a patient information sheet and those consenting to take part in the study received standardized self-tonometry training and were then instructed to measure their own IOP under observation. This study was conducted at a glaucoma clinic at a university hospital from March 1, 2016, to December 30, 2016, and included both eyes of 100 patients with glaucoma or ocular hypertension. The percentage of patients who could successfully perform self-tonometry. Complete success was defined by a good technique and an IOP reading within 5 mm Hg of that obtained by a clinician using the same device. A 3-item questionnaire was used to examine perceptions of self-tonometry among patients. Among the 100 patients, the mean (SD) age was 67.5 (10.9) years (53% female). A total 73 of 100 patients (73%) met the complete success criteria. An additional 6 patients could use the device but had IOP readings greater than 5 mm Hg different from those obtained by the clinician. On average, IOP by the rebound tonometer was 2.66 mm Hg lower than Goldmann applanation tonometry (95% limits of agreement, -3.48 to 8.80 mm Hg). The IOPs with the rebound tonometer were similar whether obtained by self-tonometry or investigator, with excellent reproducibility with an intraclass correlation coefficient of 0.903 (95% CI, 0.867-0.928). A total of 56 of 79 successful or partially successful patients (71%) felt self-tonometry was easy, with 73 of 79 (92%) reporting self-tonometry to be comfortable, and a similar number happy to perform self-tonometry in the future

  15. Vapour and air bubble collapse analysis in viscous compressible water

    Directory of Open Access Journals (Sweden)

    Gil Bazanini


    Full Text Available Numerical simulations of the collapse of bubbles (or cavities are shown, using the finite difference method, taking into account the compressibility of the liquid, expected to occur in the final stages of the collapse process. Results are compared with experimental and theoretical data for incompressible liquids, to see the influence of the compressibility of the water in the bubble collapse. Pressure fields values are calculated in an area of 800 x 800 mm, for the case of one bubble under the hypothesis of spherical symmetry. Results are shown as radius versus time curves for the collapse (to compare collapse times, and pressure curves in the plane, for pressure fields. Such calculations are new because of their general point of view, since the existing works do not take into account the existence of vapour in the bubble, neither show the pressure fields seen here. It is also expected to see the influence of the compressibility of the water in the collapse time, and in the pressure field, when comparing pressure values.

  16. Effects of the O-ring used for sealing in high-pressure balances on measurements of pressure (United States)

    Woo, S. Y.; Lee, Y. J.; Choi, I. M.; Kim, B. S.; Shin, H. H.


    An oil-operated pressure balance is standard equipment widely used in the field of pressure metrology. Most of the commonly used pressure balances are in a simple piston-cylinder configuration where the piston and the cylinder can deform freely under pressure. This simple piston-cylinder assembly has an O-ring chamber on the cylinder bottom to seal the cylinder. The effects of this O-ring seal on the effective area are not well known. This paper demonstrates by the numerical method using finite element method and the experimental method that, when performing precise measurements of pressure using a pressure balance, the cylinder will be deformed by the oil pressure exerted on the bottom of the cylinder surrounded by the O-ring, causing a non-linearity in the change of effective area, and that, when the piston-cylinder assembly is used in the body with different diameters of O-ring, the effective area, i.e. the pressure, can be significantly changed. The effects of O-ring seals on the effective area of a DH5306 oil-operated pressure balance were investigated using two piston-cylinder assemblies with nominal effective areas of 2 mm2 over the pressure range of 100-300 MPa. Three different sizes of O-ring, 4.8, 8.0 and 11.7 mm in diameter, were used. The maximum change of the effective area can reach 30 ppm at 300 MPa and 18 ppm at 100 MPa due to the change of O-ring. Therefore, for precise pressure measurement, the correct understanding of the O-ring under the cylinder is required along with checking of the size of the O-ring under the cylinder whenever calibrating the piston-cylinder assembly.

  17. Estimation of bladder contractility from intravesical pressure-volume measurements. (United States)

    Fry, Christopher H; Gammie, Andrew; Drake, Marcus John; Abrams, Paul; Kitney, Darryl Graham; Vahabi, Bahareh


    To describe parameters from urodynamic pressure recordings that describe urinary bladder contractility through the use of principles of muscle mechanics. Subtracted detrusor pressure and voided flow were recorded from patients undergoing filling cystometry. The isovolumetric increase of detrusor pressure, P, of a voluntary bladder contraction before voiding was used to generate a plot of (dP/dt)/P versus P. Extrapolation of the plot to the y-axis and the x-axis generated a contractility parameter, vCE (the maximum rate of pressure development) and the maximum isovolumetric pressure, P0 , respectively. Similar curves were obtained in ex vivo pig bladders with different concentrations of the inotropic agent carbachol and shown in a supplement. Values of vCE , but not P0 , diminished with age in female subjects. vCE was most significantly associated with the 20-80% duration of isovolumetric contraction t20-80 ; and a weaker association with maximum flow rate and BCI in women. P0 was not associated with any urodynamic variable in women, but in men was with t20-80 and isovolumetric pressure indices. The rate of isovolumetric subtracted detrusor pressure (t20-80 ) increase shows a very significant association with indices of bladder contractility as derived from a derived force-velocity curve. We propose that t20-80 is a detrusor contractility parameter (DCP). Neurourol. Urodynam. 36:1009-1014, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  18. Performance evaluation of Honeywell silicon piezoresistive pressure transducers for oceanographic and limnological measurements

    Digital Repository Service at National Institute of Oceanography (India)

    VijayKumar, K.; Joseph, A.; Desai, R.G.P.; Prabhudesai, S.; Nagvekar, S.; Damodaran, V.

    and limnological measurements, have been carried out at four differing temperatures (10 degrees, 20 degrees, 30 degrees, and 40 degrees C) to evaluate their suitability for such applications. The full-scale pressure range of these shallow water absolute pressure...

  19. Condensation of water vapour on moss-dominated biological soil ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 123; Issue 2 ... Condensation; water vapour; desert ecosystem; moss; biological soil crust. Abstract. Characteristics of water vapour condensation, including the onset, duration, and amount of water vapour condensation on moss-dominated biological soil crust ...

  20. Skin perfusion pressure on the legs measured as the external pressure required for skin reddening after blanching

    DEFF Research Database (Denmark)

    Holstein, P; Nielsen, P.E.; Lund, P


    The skin perfusion on the calf was measured photo-electrically and by isotope washout technique using external counter pressure by a blood pressure cuff. By the photocell the skin blanching threshold external pressure (BTEP) was recorded on histamine flared red skin. By isotope washout technique......-187) compared to 80.8 mmHg (range 18-158) (P > 0.1). A normal material was obtained from twenty-four subjects measured on the thigh, calf and ankle; the average gradients between the auscultatory brachial mean blood pressure and the BTEP were: thigh 10.7 mmHg (SD 12.7); calf 4.0 mmHg (SD 12.1); ankle 5.1 mm......Hg (SD 8.7). As compared to the intra-arterial blood pressure the BTEP was found to lie close to the mean blood pressure in normal subjects as well as in hypertensive subjects. The present data indicate that the skin perfusion pressure on the legs can be measured by the rapid photo-electric technique...

  1. Thirty-minute compared to standardised office blood pressure measurement in general practice.

    NARCIS (Netherlands)

    Scherpbier-de Haan, N.D.; Wel, M. van der; Schoenmakers, G.; Boudewijns, S.; Peer, P.G.M.; Weel, C. van; Thien, Th.; Bakx, J.C.


    Background Although blood pressure measurement is one of the most frequently performed measurements in clinical practice, there are concerns about its reliability. Serial, automated oscillometric blood pressure measurement has the potential to reduce measurement bias and white-coat effect' Aim To

  2. Adjustable Sample Holder With Pressure Contacts for Photoconductivity Measurement


    Sanjeev Kumar


    A sample holder is designed to hold and apply pressure contacts on the electrodes of the photoconducting material to study the photoresponse transient. The sample holder is assembled on an aluminium base plate. The needle pointed probes are constrained to move under the spring action to provide the pressure contacts. One of the probes is provided with the facility of ± x directional movement to provide contacts on the samples having different spacing between the electrodes. The setup is simpl...

  3. Novel formula to measure mean pulmonary artery pressure

    Directory of Open Access Journals (Sweden)

    Francisco Jose Chacon-Lozsan


    Full Text Available Mean Pulmonary Arterial Pressure (MPAP is an important parameter in evaluation of patients with pulmonary hypertension. The aim of this study is to correlate a new formula using non-invasive blood pressure and Bernoulli’s right ventricle systolic pressure (RVSP with invasive method. To archive the objectives, we enrolled 143 patients with suspected pulmonary hypertension from January 2015 till January 2016; all patients underwent right heart catheter evaluation and simultaneously RVSP by transthoracic echocardiography and non-invasive blood pressure to calculate MPAP by the formula MPAP = Pulse Pressure / (Mean Arterial Pressure/RVSP; and the results were compared using the Pearson’s simple-linear correlation method. We found a significant association between invasive and equation results with a Pearson’s correlation of 0,872 with a confidence interval from 0,795 to 0,921; sensitivity was 1,538% with a 95% confidence of interval (CI from 0,038% to 8,276%, and Specificity was 100% with 95% CI from 94,48% to 100%. Our results suggest that the new formula have a good correlation estimating MPAP compared with invasive right heart catheterization method.

  4. Chemical vapour deposited diamonds for dosimetry of radiotherapeutical beams

    Energy Technology Data Exchange (ETDEWEB)

    Bucciolini, M.; Mazzocchi, S. [Firenze Univ., Firenze (Italy). Dipartimento di Fisiopatologia Clinica; INFN, Firenze (Italy); Borchi, E.; Bruzzi, M.; Pini, S.; Sciortino, S. [Firenze Univ., Firenze (Italy). Dipartimento di Energetica; INFN, Firenze (Italy); Cirrone, G.A.P.; Guttone, G.; Raffaele, L.; Sabini, M.G. [INFN, Catania (Italy). Laboratori Nazionali del Sud


    This paper deals with the application of synthetic diamond detectors to the clinical dosimetry of photon and electron beams. It has been developed in the frame of INFN CANDIDO project and MURST Cofin. Diamonds grown with CVD (Chemical Vapour Deposition) technique have been studied; some of them are commercial samples while others have been locally synthesised. Experiments have been formed using both on-line and off-line approaches. For the off-line measurements, TL (thermoluminescent) and TSC (thermally stimulated current) techniques have been used.

  5. Influence of water vapour and permanent gases on the atmospheric optical depths and transmittance (United States)

    Badescu, V.


    The influence of the atmospheric state on the extinction of direct solar radiation has been studied by using a four layer atmospheric model. Simple analytical formulae are established for the spectral optical depths of permanent gases and water vapour. These formulae use the ground level values of air pressure, temperature and relative huniidity. An additional parameter, related to the vertical distribution of the hunmidity content, is used for a better estimation of the water vapour optical depth. Good agreement between theory and measurements is found. The paper shows the dependence of the atmospheric spectral transmittance on the above mentioned parameters. L'influence de l'état atmosphérique sur l'extinction de la radiation solaire directe a été étudiée à l'aide d'un modèle atmosphérique développé antérieurement par l'auteur. Des formules simples ont été établies pour l'épaisseur optique spectrale des gaz et de la vapeur d'eau. Ces formules utilisent les valeurs de la pression atmosphérique, de la température et de l'humidité relative, mesurées au niveau du sol. Un paramètre supplémentaire, lié à la distribution verticale du contenu d'humidité, est utilisé pour calculer l'épaisseur optique due à la vapeur d'eau. La théorie est en bon accord avec les résultats des mesures. Le travail montre la dépendance de la transmittance atmosphérique spectrale en fonction des paramètres spécifiés ci-dessus.

  6. Synthesis of Tin Nitride Sn x N y Nanowires by Chemical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    Othonos Andreas


    Full Text Available Abstract Tin nitride (Sn x N y nanowires have been grown for the first time by chemical vapour deposition on n-type Si(111 and in particular by nitridation of Sn containing NH4Cl at 450 °C under a steady flow of NH3. The Sn x N y nanowires have an average diameter of 200 nm and lengths ≥5 μm and were grown on Si(111 coated with a few nm’s of Au. Nitridation of Sn alone, under a flow of NH3is not effective and leads to the deposition of Sn droplets on the Au/Si(111 surface which impedes one-dimensional growth over a wide temperature range i.e. 300–800 °C. This was overcome by the addition of ammonium chloride (NH4Cl which undergoes sublimation at 338 °C thereby releasing NH3and HCl which act as dispersants thereby enhancing the vapour pressure of Sn and the one-dimensional growth of Sn x N y nanowires. In addition to the action of dispersion, Sn reacts with HCl giving SnCl2which in turn reacts with NH3leading to the formation of Sn x N y NWs. A first estimate of the band-gap of the Sn x N y nanowires grown on Si(111 was obtained from optical reflection measurements and found to be ≈2.6 eV. Finally, intricate assemblies of nanowires were also obtained at lower growth temperatures.

  7. Vapour-phase crystallisation of silica from SiF4-bearing volcanic gases

    Directory of Open Access Journals (Sweden)

    M. H. G. Jacobs


    Full Text Available Thermodynamic modelling of magmatic gases shows that SiF4 may be an important F-bearing species at the high pressures typical of magma reservoirs. Upon decompression during degassing, SiF4 will react with water vapour to form HF and silica. Common magmatic gases of high-T fumaroles seem to contain too little SiF4 to be a significant source of silica, except if extremely large amounts of gas percolate through a small volume of rock, as is the case in lava domes. Only if fluorine contents of the gases exceed 1 mol% detectable amounts of silica may be formed, but such high fluorine contents have not yet been observed in natural gases. Alternatively, silica may be formed by heating of cool SiF4-rich gases circulating in cooling lava bodies. We suggest that these mechanisms may be responsible for the deposition of crystalline silica, most probably cristobalite, observed in vesicles in lavas from Lewotolo volcano (Eastern Sunda Arc, Indonesia. Silica occurs as vapour-crystallised patches in vesicles, and is sometimes associated with F-phlogopite, which further supports F-rich conditions during deposition. Because of the connection between F-rich conditions and high-K volcanism, we propose that late-stage gaseous transport and deposition of silica may be more widespread in K-rich volcanoes than elsewhere, and long-term exposure to ash from eruptions of such volcanoes could therefore carry an increased risk for respiratory diseases. The dependence of SiF4/HF on temperature reported here differs from the current calibration used for temperature measurements of fumarolic gases by remote sensing techniques, and we suggest an updated calibration.

  8. Correlation between intrasac pressure measurements of a pressure sensor and an angiographic catheter during endovascular repair of abdominal aortic aneurysm

    Directory of Open Access Journals (Sweden)

    Pierre Galvagni Silveira


    Full Text Available PURPOSE: To establish a correlation between intrasac pressure measurements of a pressure sensor and an angiographic catheter placed in the same aneurysm sac before and after its exclusion by an endoprosthesis. METHODS: Patients who underwent endovascular abdominal aortic aneurysm repair and received an EndoSureTM wireless pressure sensor implant between March 19 and December 11, 2004 were enrolled in the study. Simultaneous readings of systolic, diastolic, mean, and pulse pressure within the aneurysm sac were obtained from the catheter and the sensor, both before and after sac exclusion by the endoprosthesis (Readings 1 and 2, respectively. Intrasac pressure measurements were compared using Pearson's correlation and Student's t test. Statistical significance was set at p0.05, mean (p>0.05, and pulse (p0.05 by the sensor. CONCLUSION: The excellent agreement between intrasac pressure readings recorded by the catheter and the sensor justifies use of the latter for detection of post-exclusion abdominal aortic aneurysm pressurization.

  9. Pressure Measurement Techniques for Abdominal Hypertension: Conclusions from an Experimental Model

    Directory of Open Access Journals (Sweden)

    Sascha Santosh Chopra


    Full Text Available Introduction. Intra-abdominal pressure (IAP measurement is an indispensable tool for the diagnosis of abdominal hypertension. Different techniques have been described in the literature and applied in the clinical setting. Methods. A porcine model was created to simulate an abdominal compartment syndrome ranging from baseline IAP to 30 mmHg. Three different measurement techniques were applied, comprising telemetric piezoresistive probes at two different sites (epigastric and pelvic for direct pressure measurement and intragastric and intravesical probes for indirect measurement. Results. The mean difference between the invasive IAP measurements using telemetric pressure probes and the IVP measurements was −0.58 mmHg. The bias between the invasive IAP measurements and the IGP measurements was 3.8 mmHg. Compared to the realistic results of the intraperitoneal and intravesical measurements, the intragastric data showed a strong tendency towards decreased values. The hydrostatic character of the IAP was eliminated at high-pressure levels. Conclusion. We conclude that intragastric pressure measurement is potentially hazardous and might lead to inaccurately low intra-abdominal pressure values. This may result in missed diagnosis of elevated abdominal pressure or even ACS. The intravesical measurements showed the most accurate values during baseline pressure and both high-pressure plateaus.

  10. Characterisation of the normal right ventricular pressure-volume relation by biplane angiography and simultaneous micromanometer pressure measurements.


    Redington, A N; Gray, H. H.; Hodson, M E; Rigby, M L; Oldershaw, P.J.


    The normal right ventricular pressure-volume relation was studied by recording biplane right ventriculograms with simultaneous high fidelity pressure recordings in 10 adults found to have normal coronary arteries and haemodynamic function at diagnostic cardiac catheterisation. Right ventricular volume was measured frame by frame from digitised ventriculograms by a modification of Simpson's rule. The accuracy of this method was tested in a study of 22 human and animal right ventricular casts. ...

  11. Measurement of pleural pressure swings with a fluid-filled esophageal catheter vs pulmonary artery occlusion pressure. (United States)

    Verscheure, S; Massion, P B; Gottfried, S; Goldberg, P; Samy, L; Damas, P; Magder, S


    Pleural pressure measured with esophageal balloon catheters (Peso) can guide ventilator management and help with the interpretation of hemodynamic measurements, but these catheters are not readily available or easy to use. We tested the utility of an inexpensive, fluid-filled esophageal catheter (Peso) by comparing respiratory-induced changes in pulmonary artery occlusion (Ppao), central venous (CVP), and Peso pressures. We studied 30 patients undergoing elective cardiac surgery who had pulmonary artery and esophageal catheters in place. Proper placement was confirmed by chest compression with airway occlusion. Measurements were made during pressure-regulated volume control (VC) and pressure support (PS) ventilation. The fluid-filled esophageal catheter provided a high-quality signal. During VC and PS, change in Ppao (∆Ppao) was greater than ∆Peso (bias = -2 mm Hg) indicating an inspiratory increase in cardiac filling. During VC, ∆CVP bias was 0 indicating no change in right heart filling, but during PS, CVP fell less than Peso indicating an inspiratory increase in filling. Peso measurements detected activation of expiratory muscles, development of non-west zone 3 lung conditions during inspiration, and ventilator-triggered inspiratory efforts. A fluid-filled esophageal catheter provides a high-quality, easily accessible, and inexpensive measure of change in pleural pressure and provided insights into patient-ventilator interactions. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Oscillometric measurement of systolic and diastolic blood pressures validated in a physiologic mathematical model

    Directory of Open Access Journals (Sweden)

    Babbs Charles F


    Full Text Available Abstract Background The oscillometric method of measuring blood pressure with an automated cuff yields valid estimates of mean pressure but questionable estimates of systolic and diastolic pressures. Existing algorithms are sensitive to differences in pulse pressure and artery stiffness. Some are closely guarded trade secrets. Accurate extraction of systolic and diastolic pressures from the envelope of cuff pressure oscillations remains an open problem in biomedical engineering. Methods A new analysis of relevant anatomy, physiology and physics reveals the mechanisms underlying the production of cuff pressure oscillations as well as a way to extract systolic and diastolic pressures from the envelope of oscillations in any individual subject. Stiffness characteristics of the compressed artery segment can be extracted from the envelope shape to create an individualized mathematical model. The model is tested with a matrix of possible systolic and diastolic pressure values, and the minimum least squares difference between observed and predicted envelope functions indicates the best fit choices of systolic and diastolic pressure within the test matrix. Results The model reproduces realistic cuff pressure oscillations. The regression procedure extracts systolic and diastolic pressures accurately in the face of varying pulse pressure and arterial stiffness. The root mean squared error in extracted systolic and diastolic pressures over a range of challenging test scenarios is 0.3 mmHg. Conclusions A new algorithm based on physics and physiology allows accurate extraction of systolic and diastolic pressures from cuff pressure oscillations in a way that can be validated, criticized, and updated in the public domain.

  13. Oscillometric measurement of systolic and diastolic blood pressures validated in a physiologic mathematical model (United States)


    Background The oscillometric method of measuring blood pressure with an automated cuff yields valid estimates of mean pressure but questionable estimates of systolic and diastolic pressures. Existing algorithms are sensitive to differences in pulse pressure and artery stiffness. Some are closely guarded trade secrets. Accurate extraction of systolic and diastolic pressures from the envelope of cuff pressure oscillations remains an open problem in biomedical engineering. Methods A new analysis of relevant anatomy, physiology and physics reveals the mechanisms underlying the production of cuff pressure oscillations as well as a way to extract systolic and diastolic pressures from the envelope of oscillations in any individual subject. Stiffness characteristics of the compressed artery segment can be extracted from the envelope shape to create an individualized mathematical model. The model is tested with a matrix of possible systolic and diastolic pressure values, and the minimum least squares difference between observed and predicted envelope functions indicates the best fit choices of systolic and diastolic pressure within the test matrix. Results The model reproduces realistic cuff pressure oscillations. The regression procedure extracts systolic and diastolic pressures accurately in the face of varying pulse pressure and arterial stiffness. The root mean squared error in extracted systolic and diastolic pressures over a range of challenging test scenarios is 0.3 mmHg. Conclusions A new algorithm based on physics and physiology allows accurate extraction of systolic and diastolic pressures from cuff pressure oscillations in a way that can be validated, criticized, and updated in the public domain. PMID:22913792

  14. Glucose Monitoring System Based on Osmotic Pressure Measurements

    Directory of Open Access Journals (Sweden)

    Alexandra LEAL


    Full Text Available This paper presents the design and development of a prototype sensor unit for implementation in a long-term glucose monitoring system suitable for estimating glucose levels in people suffering from diabetes mellitus. The system utilizes osmotic pressure as the sensing mechanism and consists of a sensor prototype that is integrated together with a pre-amplifier and data acquisition unit for both data recording and processing. The sensor prototype is based on an embedded silicon absolute pressure transducer and a semipermeable nanoporous membrane that is enclosed in the sensor housing. The glucose monitoring system facilitates the integration of a low power microcontroller that is combined with a wireless inductive powered communication link. Experimental verification have proven that the system is capable of tracking osmotic pressure changes using albumin as a model compound, and thereby show a proof of concept for novel long term tracking of blood glucose from remote sensor nodes.

  15. [Mobile Health: IEEE Standard for Wearable Cuffless Blood Pressure Measuring Devices]. (United States)

    Zhou, Xia; Wu, Wenli; Bao, Shudi


    IEEE Std 1708-2014 breaks through the traditional standards of cuff based blood pressure measuring devices and establishes a normative definition of wearable cuffless blood pressure measuring devices and the objective performance evaluation of this kind of devices. This study firstly introduces the background of the new standard. Then, the standard details will be described, and the impact of cuffless blood pressure measuring devices with the new standard on manufacturers and end users will be addressed.

  16. A new estimate technology of non-invasive continuous blood pressure measurement based on electrocardiograph


    Chung-Min Wu; Chueh Yu Chuang; Yeou-Jiunn Chen; Shih-Chung Chen


    Various physiological parameters have been widely used in the prevention and detection of diseases. In particular, the occurrence of cardiovascular diseases can be observed through daily measurement of blood pressure. Currently, the most common blood pressure measurement method records blood pressure on the upper arm. This can lead to the subject feeling uncomfortable and tension in the arm from the stress may lead to measurement errors. An electrocardiogram represents the electrical activity...

  17. Apparatus to measure the vapor pressure of slowly decomposing compounds from 1 Pa to 105 Pa


    Berg, Robert F.


    This article describes an apparatus and method for measuring vapor pressures in the range from 1 Pa to 105 Pa. Its three distinctive elements are : (1) the static pressure measurements were made with only a small temperature difference between the vapor and the condensed phase, (2) the sample was degassed in situ, and (3) the temperature range extended up to 200 °C. The apparatus was designed to measure metal-organic precursors, which often are toxic, pyrophoric, or unstable. Vapor pressures ...


    NARCIS (Netherlands)

    VELDMAN, JBP; RUDDEL, H; ROBBE, HWJ; Mulder, Lambertus; Mulder, Gysbertus

    Two experiments were conducted to explore the usefulness of the Penaz method for non-invasive, continuous finger blood pressure measurements during mental stress testing. In the first study, blood pressure was measured with the Penaz method, in the second it was measured intra-arterially. Two

  19. Interface pressure measurement during surgery: a comparison of four operating table surfaces. (United States)

    Keller, B P J A; van Overbeeke, J; van der Werken, Chr


    To compare the pressure-reducing and pressure-redistributing characteristics of four operating room (OR) table mattresses using interface pressure measurements, in two positions adopted for surgical procedures. Support surfaces were randomly assigned to 80 patients. These were: an overlay pad filled with fibres (the standard OR mattress), a custom-made viscoelastic polyurethane foam mattress, an inflatable mattress with air-filled cells and a fluid mattress. An XSENSOR full-body pressure-mapping pad was used to record interface pressures of 40 patients in the supine position and 40 patients in the lithotomy position. Measurements were analysed for peak pressure, peak pressure index, total contact surface area and the occurrence of a significant increase in interface pressure during the surgical procedure. The highest interface pressures were measured on the standard mattress, in both the supine and lithotomy position. Overall, the fluid mattress showed the best pressure-reducing and pressure-redistributing capacities. As long as no reference values are available for interface pressures under which no pressure-related damage will occur, clinical testing of OR table surfaces is still necessary.

  20. Healing of ulcers on the feet correlated with distal blood pressure measurements in occlusive arterial disease

    DEFF Research Database (Denmark)

    Holstein, P; Lassen, N A


    The frequency of healing in subchronic ulcers in 66 feet in 62 patients with arterial occlusive disease was correlated with the systolic digital blood pressure (SDBP) and the systolic ankle blood pressure (SABP), both measured with a strain gauge, and with the skin perfusion pressure on the heel ...

  1. Measuring Vapor Pressure with an Isoteniscope: A Hands-on Introduction to Thermodynamic Concepts (United States)

    Chen, Wenqian; Haslam, Andrew J.; Macey, Andrew; Shah, Umang V.; Brechtelsbauer, Clemens


    Characterization of the vapor pressure of a volatile liquid or azeotropic mixture, and its fluid phase diagram, can be achieved with an isoteniscope and an industrial grade digital pressure sensor using the experimental method reported in this study. We describe vapor-pressure measurements of acetone and n-hexane and their azeotrope, and how the…

  2. Home blood pressure measurement : reproducibility and relationship with left ventricular mass

    NARCIS (Netherlands)

    Kok, R.H.; Beltman, F.W.; Terpstra, W.F.; Smit, A.J.; May, J.F.; de Graeff, P.A.; Meyboom-de Jong, B.


    OBJECTIVE: To evaluate the reproducibility and relationship with left ventricular mass index of home blood pressure in comparison with ambulatory and office blood pressures. METHODS: We measured home, ambulatory and office blood pressures of 84 previously untreated hypertensive patients, aged 60-74

  3. Aero-acoustic Measurement and Monitoring of Dynamic Pressure Fields Project (United States)

    National Aeronautics and Space Administration — This innovative and practical measurement and monitoring system optimally defines dynamic pressure fields, including sound fields. It is based on passive acoustic...

  4. X-ray reflectivity measurements of liquid/solid interfaces under high hydrostatic pressure conditions. (United States)

    Wirkert, Florian J; Paulus, Michael; Nase, Julia; Möller, Johannes; Kujawski, Simon; Sternemann, Christian; Tolan, Metin


    A high-pressure cell for in situ X-ray reflectivity measurements of liquid/solid interfaces at hydrostatic pressures up to 500 MPa (5 kbar), a pressure regime that is particularly important for the study of protein unfolding, is presented. The original set-up of this hydrostatic high-pressure cell is discussed and its unique properties are demonstrated by the investigation of pressure-induced adsorption of the protein lysozyme onto hydrophobic silicon wafers. The presented results emphasize the enormous potential of X-ray reflectivity studies under high hydrostatic pressure conditions for the in situ investigation of adsorption phenomena in biological systems.

  5. Measurement of Aeroplane Takeoff Speed and Cabin Pressure. (United States)

    Wardle, D. A.


    Describes two experiments in which a pendulum was used to determine acceleration along the runway during the takeoff of a plane and the takeoff speed. Uses a water-filled nanometer to determines the drop in cabin pressure during the flight. (CCM)

  6. Measures of blood pressure and cognition in dialysis patients (United States)

    There are few reports on the relationship of blood pressure with cognitive function in maintenance dialysis patients. The Cognition and Dialysis Study is an ongoing investigation of cognitive function and its risk factors in six Boston area hemodialysis units. In this analysis, we evaluated the rela...

  7. Clinical implications of non-invasive measurement of central aortic blood pressure. (United States)

    Stepień, Mariusz; Banach, Maciej; Jankowski, Piotr; Rysz, Jacek


    Central arterial systolic blood pressure is a very important factor in the pathophysiology of cardiovascular diseases. Central arterial pressure is a better predictor of cardiovascular risk than peripheral brachial blood pressure. Measurement of central blood pressure is useful for a diagnosis of spurious systolic hypertension in young people. Antihypertensive drugs have a different impact on central blood pressure, for example angiotensin converting enzyme inhibitors, antagonists of angiotensin II receptors, calcium channel blockers more effectively lower central blood pressure than betablockers, despite all of those drugs (including beta-blockers) having a similar impact on peripheral pressure. This mechanism may be responsible for the beneficial effect of some antihypertensive drugs on cardiovascular end points observed in clinical trials, despite a low peripheral hypotensive effect. However, further clinical trials are required to provide more evidence for the prognostic and therapeutic implications of the measurement of central blood pressure before adopting its routine application in clinical practice.

  8. An evaluation of pressure and flow measurement in the Molten Salt Test Loop (MSTL) system.

    Energy Technology Data Exchange (ETDEWEB)

    Gill, David Dennis; Kolb, William J.; Briggs, Ronald J.


    The National Solar Thermal Test Facility at Sandia National Laboratories has a unique test capability called the Molten Salt Test Loop (MSTL) system. MSTL allows customers and researchers to test components in flowing, molten nitrate salt at plant-like conditions for pressure, flow, and temperature. An important need in thermal storage systems that utilize molten salts is for accurate flow and pressure measurement at temperatures above 535ÀC. Currently available flow and pressure instrumentation for molten salt is limited to 535ÀC and even at this temperature the pressure measurement appears to have significant variability. It is the design practice in current Concentrating Solar Power plants to measure flow and pressure on the cold side of the process or in dead-legs where the salt can cool, but this practice wont be possible for high temperature salt systems. For this effort, a set of tests was conducted to evaluate the use of the pressure sensors for flow measurement across a device of known flow coefficient Cv. To perform this task, the pressure sensors performance was evaluated and was found to be lacking. The pressure indicators are severely affected by ambient conditions and were indicating pressure changes of nearly 200psi when there was no flow or pressure in the system. Several iterations of performance improvement were undertaken and the pressure changes were reduced to less than 15psi. The results of these pressure improvements were then tested for use as flow measurement. It was found that even with improved pressure sensors, this is not a reliable method of flow measurement. The need for improved flow and pressure measurement at high temperatures remains and will need to be solved before it will be possible to move to high temperature thermal storage systems with molten salts.

  9. Remote sensing of water vapour profiles in the framework of the Total Carbon Column Observing Network (TCCON

    Directory of Open Access Journals (Sweden)

    M. Schneider


    Full Text Available We show that the near infrared solar absorption spectra recorded in the framework of the Total Carbon Column Observing Network (TCCON can be used to derive the vertical distribution of tropospheric water vapour. The resolution of the TCCON spectra of 0.02 cm−1 is sufficient for retrieving lower and middle/upper tropospheric water vapour concentrations with a vertical resolution of about 3 and 8 km, respectively. We document the good quality of the remotely-sensed profiles by comparisons with coincident in-situ Vaisala RS92 radiosonde measurements. Due to the high measurement frequency, the TCCON water vapour profile data offer novel opportunities for estimating the water vapour variability at different timescales and altitudes.

  10. Nanocomposite-Based Microstructured Piezoresistive Pressure Sensors for Low-Pressure Measurement Range

    Directory of Open Access Journals (Sweden)

    Vasileios Mitrakos


    Full Text Available Piezoresistive pressure sensors capable of detecting ranges of low compressive stresses have been successfully fabricated and characterised. The 5.5 × 5 × 1.6 mm3 sensors consist of a planar aluminium top electrode and a microstructured bottom electrode containing a two-by-two array of truncated pyramids with a piezoresistive composite layer sandwiched in-between. The responses of two different piezocomposite materials, a Multiwalled Carbon Nanotube (MWCNT-elastomer composite and a Quantum Tunneling Composite (QTC, have been characterised as a function of applied pressure and effective contact area. The MWCNT piezoresistive composite-based sensor was able to detect pressures as low as 200 kPa. The QTC-based sensor was capable of detecting pressures as low as 50 kPa depending on the contact area of the bottom electrode. Such sensors could find useful applications requiring the detection of small compressive loads such as those encountered in haptic sensing or robotics.

  11. Proposal to Measure Hadron Scattering with a Gaseous High Pressure TPC for Neutrino Oscillation Measurements

    CERN Document Server

    Andreopoulos, C; Bordoni, S; Boyd, S; Brailsford, D; Brice, S; Catanesi, G; Chen-Wishart, Z; Denner, P; Dunne, P; Giganti, C; Gonzalez Diaz, D; Haigh, J; Hamacher-Baumann, P; Hallsjo, S; Hayato, Y; Irastorza, I; Jamieson, B; Kaboth, A; Korzenev, A; Kudenko, Y; Leyton, M; Luk, K-B; Ma, W; Mahn, K; Martini, M; McCauley, N; Mermod, P; Monroe, J; Mosel, U; Nichol, R; Nieves, J; Nonnenmacher, T; Nowak, J; Parker, W; Raaf, J; Rademacker, J; Radermacher, T; Radicioni, E; Roth, S; Saakyan, R; Sanchez, F; Sgalaberna, D; Shitov, Y; Sobczyk, J; Soler, F; Touramanis, C; Valder, S; Walding, J; Ward, M; Wascko, M; Weber, A; Yokoyama, M; Zalewska, A; Ziembicki, M


    We propose to perform new measurements of proton and pion scattering on argon using a prototype High Pressure gas Time Projection Chamber (HPTPC) detector, and by doing so to develop the physics case for, and the technological readiness of, an HPTPC as a neutrino detector for accelerator neutrino oscillation searches. The motivation for this work is to improve knowledge of final state interactions, in order to ultimately achieve 1-2% systematic error on neutrino-nucleus scattering for oscillation measurements at 0.6 GeV and 2.5 GeV neutrino energy, as required for the Charge-Parity (CP) violation sensitivity projections by the Hyper-Kamiokande experiment (Hyper-K) and the Deep Underground Neutrino Experiment (DUNE). The final state interaction uncertainties in neutrino-nucleus interactions dominate cross-section systematic errors, currently 5–10% at these energies, and therefore R&D is needed to explore new approaches to achieve this substantial improvement.

  12. Pressure drop measurement for flow-measuring dummy fuel assemblies in HANARO core

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Heon Il; Chae, Hee Taek; Chung, Heung June [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)


    In order to characterize the flow distribution of HANARO core, flow-rate measuring dummy fuel assemblies (instrumented dummy fuel assemblies) were to be used in the HANARO commissioning. To do this instrumented dummy fuel assemblies were developed and the calibration tests were conducted in the thermal-hydraulic laboratory. Through this experiment the correlations for 6 instrumented dummy fuel assemblies were derived. The measured total pressure drop for the 36-element dummy fuel assembly was 211 kPa, which meets the design requirement, 209 kPa {+-} 5%. The form loss coefficients for the spacers were re-evaluated and the new correlation was obtained. 7 tabs., 13 figs., 2 refs. (Author).

  13. Reliability and applicability of DSTs and bottomhole pressure measurements in Texas Gulf Coast Tertiary formations

    Energy Technology Data Exchange (ETDEWEB)

    Akhter, M.S.; Kreitler, C.W. (Texas Univ., Austin, TX (USA))


    Pressure data gathered from drillstem tests (DSTs) and bottomhole pressure measurements provide critical information toward formation evaluation and can be used for an assessment of prevailing pressure regimes and their influence on the migration potential of formation fluids. Reliability of such pressure data is an issue of major concern in reservoir engineering practice and can be established through an appropriate screening procedure. 17 figs., 10 refs.

  14. Towards a standard for the dynamic measurement of pressure based on laser absorption spectroscopy. (United States)

    Douglass, K O; Olson, D A


    We describe an approach for creating a standard for the dynamic measurement of pressure based on the measurement of fundamental quantum properties of molecular systems. From the linewidth and intensities of ro-vibrational transitions we plan on making an accurate determination of pressure and temperature. The goal is to achieve an absolute uncertainty for time-varying pressure of 5 % with a measurement rate of 100 kHz, which will in the future serve as a method for the traceable calibration of pressure sensors used in transient processes. To illustrate this concept we have used wavelength modulation spectroscopy (WMS), due to inherent advantages over direct absorption spectroscopy, to perform rapid measurements of carbon dioxide in order to determine the pressure. The system records the full lineshape profile of a single ro-vibrational transition of CO2 at a repetition rate of 4 kHz and with a systematic measurement uncertainty of 12 % for the linewidth measurement. A series of pressures were measured at a rate of 400 Hz (10 averages) and from these measurements the linewidth was determined with a relative uncertainty of about 0.5 % on average. The pressures measured using WMS have an average difference of 0.6 % from the absolute pressure measured with a capacitance diaphragm sensor.

  15. Measuring Negative Pore Pressures in Partially Frozen Saturated Soils


    Holten, Johannes Gaspar


    Freezing of soil is an issue which has many implications on modern infrastructure, in which frost heave plays a pivotal role. During freezing the behavior of the soil and the flow of water is altered. In an engineering perspective, it is important to grasp the driving forces behind these behavioral changes. The main contributor to frost heave is the development of a large negative pore pressure in the unfrozen water in partially frozen fine-grained soil, termed cryosuction. The suction leads...

  16. Simplified heat transfer modeling for Vapour Phase Soldering based on filmwise condensation for different horizontal Printed Circuit Boards (United States)

    Géczy, Attila; Illés, Balázs; Péter, Zsolt; Illyefalvi-Vitéz, Zsolt


    The paper presents a method for investigating heat transfer during a specific reflow soldering method, Vapour Phase Soldering (VPS), where a horizontal Printed Circuit Board (PCB) is heated in vapour medium. The paper presents refined descriptions of filmwise condensation which were investigated and adjusted for the VPS process. The results show a proper and fast approximation of measurements. The dependence of the PCB characteristic length is also investigated.

  17. Prediction of clothing thermal insulation and moisture vapour resistance of the clothed body walking in wind. (United States)

    Qian, Xiaoming; Fan, Jintu


    Clothing thermal insulation and moisture vapour resistance are the two most important parameters in thermal environmental engineering, functional clothing design and end use of clothing ensembles. In this study, clothing thermal insulation and moisture vapour resistance of various types of clothing ensembles were measured using the walking-able sweating manikin, Walter, under various environmental conditions and walking speeds. Based on an extensive experimental investigation and an improved understanding of the effects of body activities and environmental conditions, a simple but effective direct regression model has been established, for predicting the clothing thermal insulation and moisture vapour resistance under wind and walking motion, from those when the manikin was standing in still air. The model has been validated by using experimental data reported in the previous literature. It has shown that the new models have advantages and provide very accurate prediction.

  18. Field measurement of local ice pressures on the ARAON in the Beaufort Sea

    Directory of Open Access Journals (Sweden)

    Tak-Kee Lee


    Full Text Available This study conducted four field measurements of local ice pressure during the icebreaking voyage of the icebreaking research vessel “ARAON” in the Chukchi and Beaufort seas from July to August of 2010. For measurements, 14 strain gauges, including 8 strain gauge rosettes, were set on the bow of the port side. Influence coefficients were determined using a finite element model of the instrumented area and they were used to convert the measured strains on the hull structure to local ice pressures. The converted maximum pressure was calculated as 2.12 MPa on an area of 0.28 m2. Pressure-area curves were developed from the surveyed pressure data and the results were compared with previously measured data. The study results are expected to provide an understanding of local ice pressures and thus be useful in the structural design of ice class ships.

  19. Influence on Calculated Blood Pressure of Measurement Posture for the Development of Wearable Vital Sign Sensors

    Directory of Open Access Journals (Sweden)

    Shouhei Koyama


    Full Text Available We studied a wearable blood pressure sensor using a fiber Bragg grating (FBG sensor, which is a highly accurate strain sensor. This sensor is installed at the pulsation point of the human body to measure the pulse wave signal. A calibration curve is built that calculates the blood pressure by multivariate analysis using the pulse wave signal and a reference blood pressure measurement. However, if the measurement height of the FBG sensor is different from the reference measurement height, an error is included in the reference blood pressure. We verified the accuracy of the blood pressure calculation with respect to the measurement height difference and the posture of the subject. As the difference between the measurement height of the FBG sensor and the reference blood pressure measurement increased, the accuracy of the blood pressure calculation decreased. When the measurement height was identical and only posture was changed, good accuracy was achieved. In addition, when calibration curves were built using data measured in multiple postures, the blood pressure of each posture could be calculated from a single calibration curve. This will allow miniaturization of the necessary electronics of the sensor system, which is important for a wearable sensor.

  20. Advanced lifetime PSP imaging system for pressure and temperature field measurement (United States)

    Mitsuo, Kazunori; Asai, Keisuke; Takahashi, Akira; Mizushima, Hiroshi


    The newly designed lifetime imaging system (LIS), which was composed of a multi-gated CCD camera and LED illuminators, has been developed to measure simultaneously pressure and temperature field from luminescent lifetime decay of pressure-sensitive paint (PSP). The new system could reduce the measurement error due to shot noise of a CCD and laser speckle, compared to the previous lifetime imaging system. Optimization of PSP film thickness on white basecoat was also conducted for improving measurement accuracy, and could minimize the measurement error. As a verification test, pressure and temperature images on a simple delta wing were visualized by the newly designed LIS. The quality of the pressure image was considerably improved in comparison with that measured by the previous system. These results indicated that the new LIS was a practical measurement tool to acquire simultaneously pressure and temperature field on an aerodynamic model surface.

  1. Design, Manufacture and Testing of Capacitive Pressure Sensors for Low-Pressure Measurement Ranges

    Directory of Open Access Journals (Sweden)

    Vasileios Mitrakos


    Full Text Available This article presents the design, manufacture and testing of a capacitive pressure sensor with a high, tunable performance to low compressive loads (<10 kPa and a resolution of less than 0.5 kPa. Such a performance is required for the monitoring of treatment efficacy delivered by compression garments to treat or prevent medical conditions such as deep vein thrombosis, leg ulcers, varicose veins or hypertrophic scars. Current commercial sensors used in such medical applications have been found to be either impractical, costly or of insufficient resolution. A microstructured elastomer film of a polydimethylsiloxane (PDMS blend with a tunable Young’s modulus was used as the force-sensing dielectric medium. The resulting 18 mm × 18 mm parallel-plate capacitive pressure sensor was characterised in the range of 0.8 to 6.5 kPa. The microstructuring of the surface morphology of the elastomer film combined with the tuning of the Young’s modulus of the PDMS blend is demonstrated to enhance the sensor performance achieving a 0.25 kPa pressure resolution and a 10 pF capacitive change under 6.5 kPa compressive load. The resulting sensor holds good potential for the targeted medical application.

  2. Temperature-dependent transport mechanisms through PE-CVD coatings: comparison of oxygen and water vapour (United States)

    Kirchheim, D.; Wilski, S.; Jaritz, M.; Mitschker, F.; Gebhard, M.; Brochhagen, M.; Böke, M.; Benedikt, Jan; Awakowicz, P.; Devi, A.; Hopmann, Ch; Dahlmann, R.


    When it comes to thin coatings such as plasma-enhanced chemical vapour deposition or plasma-enhanced atomic layer deposition coatings on substrates of polymeric material, existing models often describe transport through these thin coatings as mainly driven by transport through defects of different sizes. However, temperature-dependent measurements of permeation could not confirm this hypothesis and instead gaseous transport through these thin coatings was found to more likely to occur through the molecular structure. This paper correlates existing transport models with data from oxygen transmission experiments and puts recent investigations for water vapour transmission mechanisms into context for a better understanding of gaseous transport through thin coatings.

  3. Comparison of ultrasonic Doppler flow monitor, oscillometric, and direct arterial blood pressure measurements in ill dogs. (United States)

    Bosiack, Ann P; Mann, F A; Dodam, John R; Wagner-Mann, Colette C; Branson, Keith R


    To compare blood pressure measurements obtained via ultrasonic Doppler flow monitor (DOP) and 2 oscillometric noninvasive blood pressure monitors (CAR and PAS) to invasive blood pressure (IBP) in hospitalized, conscious dogs with a range of blood pressures. Prospective clinical study. University teaching hospital. Eleven client-owned dogs aged between 4 months and 11.5 years (median 6 y), and weighing between 5.8 and 37.5 kg (median 30.2 kg). Blood pressure measurement. Three consecutive measurements of systolic, diastolic, and mean arterial pressure (MAP) were recorded for each of the 3 indirect devices (only systolic for DOP), along with concurrent IBP measurements. The data were categorized into 3 groups: hypotensive (direct MAPor=100 mm Hg), and hypertensive (direct MAP>100 mm Hg). Each indirect method was compared with the corresponding direct arterial pressure using the Bland-Altman method. Within the hypotensive group, each indirect method overestimated the corresponding IBP. Within the normotensive group all indirect systolic measurements and the PAS diastolic measurements underestimated the corresponding IBP. The remaining indirect measurements overestimated the corresponding IBP. Within the hypertensive group, DOP and CAR systolic measurements underestimated the corresponding IBP, and the remaining indirect measurements overestimated the corresponding IBP. In hypertensive dogs oscillometric systolic measurements were more accurate than MAP. In hypotensive dogs MAP measurements were more accurate than systolic measurements. All indirect measurements were most accurate in hypertensive dogs. The noninvasive blood pressure monitors in our study did not meet the validation standards set in human medicine. However, CAR diastolic and MAP measurements within the normotensive group, CAR MAP measurements within the hypertensive group, and PAS diastolic measurements in all groups were close to these standards. All indirect measurements showed greater bias during

  4. The importance of the poikilohydric nature of lichens as natural tracers for delta18O of ambient vapour (United States)

    Hartard, Britta; Cuntz, Matthias; Lakatos, Michael; Máguas, Cristina


    The stable isotope composition of water is routinely used as a tracer to study water exchange processes in vascular plants and ecosystems. To date, no study has focussed on isotope processes in poikilohydric organisms (i.e. lichens and bryophytes), where relative water content equilibrate with the surrounding humidity conditions and that are able to use distinct water sources such as precipitation, dew, fog and also water vapour. Moreover, lichens are ubiquitous organisms, and on a global scale, they are found in nearly all terrestrial ecosystems and also within these ecosystems they inhabit many microhabitats. As poikilohydric. especially green algal lichens are known to photosynthetically reactivate solely upon uptake of atmospheric moisture, even at non-saturated ambient humidity conditions. To understand basic isotope exchange processes on non-vascular plants, thallus water isotopic composition was studied in various green-algal lichens exposed to desiccation. The study indicates that lichens equilibrates with the isotopic composition of surrounding water vapour. We found that the thallus water of lichens exposed to high relative humidity shows fast isotopic equilibration with the surrounding vapour regardless of whether the lichen experiences water loss or vapour uptake. The time until isotopic equilibrium is achieved depends on the initial water status as well as on the lichen's specific morphology. It ranged from 5 to 12h in previously dried lichens to approximately 40h in lichens previously rehydrated with liquid water of distinct isotopic composition. Even though markedly slower, isotopic equilibration between leaf water and ambient vapour may also occur in homoiohydric plants exposed to high relative humidity. At low relative humidity, however, the apparent vapour pressure deficit between the evaporative sites and the ambient air and the increased stomatal diffusion resistance generally causes leaf water enrichment. In contrast, poikilohydric lichens lack

  5. The measurement of digital systolic blood pressure by strain gauge technique

    DEFF Research Database (Denmark)

    Nielsen, P E; Bell, G; Lassen, N A


    The systolic blood pressure on the finger, toe, and ankle has been measured by a strain gauge technique in 10 normal subjects aged 17-31 years and 14 normal subjects aged 43-57 years. The standard deviation in repeated measurements lies between 2 and 6 mm Hg. The finger pressure in the younger gr...

  6. Accuracy of non-invasive blood pressure measurements in obese patients. (United States)

    Arnold, Abigail; McNaughton, Amanda


    This article describes an evidence-based literature review, comparing upper arm and forearm blood pressure measurements using non-invasive devices on obese patients. The focus on blood pressure monitoring was in response to regularly witnessing inappropriately applied blood pressure cuffs on obese patient's upper arms in practice. An inaccurately obtained blood pressure measurement can result in the misdiagnosis and treatment of hypertension. As the prevalence of obesity grows worldwide, healthcare settings need to ensure they have the necessary equipment and trained staff to accurately measure obese patients' blood pressure. The aim of this review was to identify whether a forearm measurement provided a suitable alternative to upper arm measurements. The article discusses the development and execution of a search strategy, as well as the critical appraisal of a selected article. The results of the review demonstrated that forearm blood pressure measurements in obese patients do not replace upper arm blood pressure measurements taken with an appropriate cuff. It is recommended that further research is undertaken in order to identify suitable alternatives for obtaining an accurate non-invasive blood pressure measurement in obese patients.

  7. Validation of the urine column measurement as an estimation of the intra-abdominal pressure.

    NARCIS (Netherlands)

    Steeg, H.J.J. van der; Akkeren, J.P. van; Houterman, S.; Roumen, R.M.H.


    OBJECTIVE: To evaluate the efficacy of the urine column (UC) measurement compared to the intra-vesicular pressure (IVP) measurement as an estimation of intra-abdominal pressure (IAP) in patients with IAP up to 30 mmHg. METHODS: Fifteen patients undergoing a laparoscopic cholecystectomy were studied.

  8. Prediction of walking speed using single stance force or pressure measurements in healthy subjects

    NARCIS (Netherlands)

    Keijsers, N.L.W.; Stolwijk, N.M.; Renzenbrink, G.J.; Duysens, J.


    Walking speed is one of the best measures of overall walking capacity. In plantar pressure measurements, walking speed can be assessed using contact time, but it is only moderately correlated with walking speed. The center of pressure might be of more value to indicate walking speed since walking

  9. The position of the arm during blood pressure measurement in sitting position.

    NARCIS (Netherlands)

    Adiyaman, A.; Verhoeff, R.; Lenders, J.W.M.; Deinum, J.; Thien, Th.


    OBJECTIVE: Determining the influence of the position of the arm on blood pressure measurement in the sitting position. METHODS: Blood pressure of 128 individuals (the majority being treated hypertensive patients) visiting the outpatient clinic was measured simultaneously on both arms with arms in

  10. Arterial pressure measurement: Is the envelope curve of the oscillometric method influenced by arterial stiffness?

    Energy Technology Data Exchange (ETDEWEB)

    Gelido, G [Electronic department, Universidad Tecnologica Nacional FRBA, Bs. As. (Argentina); Angiletta, S [Electronic department, Universidad Tecnologica Nacional FRBA, Bs. As. (Argentina); Pujalte, A [Electronic department, Universidad Tecnologica Nacional FRBA, Bs. As. (Argentina); Quiroga, P [Electronic department, Universidad Favaloro FICEN, Bs. As. (Argentina); Cornes, P [Electronic department, Universidad Favaloro FICEN, Bs. As. (Argentina); Craiem, D [Electronic department, Universidad Favaloro FICEN, Bs. As. (Argentina)


    Measurement of peripheral arterial pressure using the oscillometric method is commonly used by professionals as well as by patients in their homes. This non invasive automatic method is fast, efficient and the required equipment is affordable with a low cost. The measurement method consists of obtaining parameters from a calibrated decreasing curve that is modulated by heart beats witch appear when arterial pressure reaches the cuff pressure. Diastolic, mean and systolic pressures are obtained calculating particular instants from the heart beats envelope curve. In this article we analyze the envelope of this amplified curve to find out if its morphology is related to arterial stiffness in patients. We found, in 33 volunteers, that the envelope waveform width correlates to systolic pressure (r=0.4, p<0.05), to pulse pressure (r=0.6, p<0.05) and to pulse pressure normalized to systolic pressure (r=0.6, p<0.05). We believe that the morphology of the heart beats envelope curve obtained with the oscillometric method for peripheral pressure measurement depends on arterial stiffness and can be used to enhance pressure measurements.

  11. Evaluation of niobium dimethylamino-ethoxide for chemical vapour deposition of niobium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dabirian, Ali [Laboratory for Photonic Materials and Characterization, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 17, 1015 Lausanne (Switzerland); Kuzminykh, Yury, E-mail: [Laboratory for Photonic Materials and Characterization, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 17, 1015 Lausanne (Switzerland); Laboratory for Advanced Materials Processing, Empa, Swiss Federal Laboratories for Materials Science and Technology, Feuerwerkerstrasse 39, 3602 Thun (Switzerland); Wagner, Estelle; Benvenuti, Giacomo [3D-Oxides, 70 Rue G. Eiffel Technoparc, 01630 St Genis Pouilly (France); ABCD Technology, 12 route de Champ-Colin, 1260 Nyon (Switzerland); Rushworth, Simon [Tyndall National Institute, Lee Maltings, Dyke Parade, Cork (Ireland); Hoffmann, Patrik, E-mail: [Laboratory for Photonic Materials and Characterization, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 17, 1015 Lausanne (Switzerland); Laboratory for Advanced Materials Processing, Empa, Swiss Federal Laboratories for Materials Science and Technology, Feuerwerkerstrasse 39, 3602 Thun (Switzerland)


    Chemical vapour deposition (CVD) processes depend on the availability of suitable precursors. Precursors that deliver a stable vapour pressure are favourable in classical CVD processes, as they ensure process reproducibility. In high vacuum CVD (HV-CVD) process vapour pressure stability of the precursor is of particular importance, since no carrier gas assisted transport can be used. The dimeric Nb{sub 2}(OEt){sub 10} does not fulfil this requirement since it partially dissociates upon heating. Dimethylamino functionalization of an ethoxy ligand of Nb(OEt){sub 5} acts as an octahedral field completing entity and leads to Nb(OEt){sub 4}(dmae). We show that Nb(OEt){sub 4}(dmae) evaporates as monomeric molecule and ensures a stable vapour pressure and, consequently, stable flow. A set of HV-CVD experiments were conducted using this precursor by projecting a graded molecular beam of the precursor onto the substrate at deposition temperatures from 320 °C to 650 °C. Film growth rates ranging from 8 nm·h{sup −1} to values larger than 400 nm·h{sup −1} can be obtained in this system illustrating the high level of control available over the film growth process. Classical CVD limiting conditions along with the recently reported adsorption–reaction limited conditions are observed and the chemical composition, and microstructural and optical properties of the films are related to the corresponding growth regime. Nb(OEt){sub 4}(dmae) provides a large process window of deposition temperatures and precursor fluxes over which carbon-free and polycrystalline niobium oxide films with growth rates proportional to precursor flux are obtained. This feature makes Nb(OEt){sub 4}(dmae) an attractive precursor for combinatorial CVD of niobium containing complex oxide films that are finding an increasing interest in photonics and photoelectrochemical water splitting applications. The adsorption–reaction limited conditions provide extremely small growth rates comparable to an

  12. Flexible Piezoelectric-Induced Pressure Sensors for Static Measurements Based on Nanowires/Graphene Heterostructures. (United States)

    Chen, Zefeng; Wang, Zhao; Li, Xinming; Lin, Yuxuan; Luo, Ningqi; Long, Mingzhu; Zhao, Ni; Xu, Jian-Bin


    The piezoelectric effect is widely applied in pressure sensors for the detection of dynamic signals. However, these piezoelectric-induced pressure sensors have challenges in measuring static signals that are based on the transient flow of electrons in an external load as driven by the piezopotential arisen from dynamic stress. Here, we present a pressure sensor with nanowires/graphene heterostructures for static measurements based on the synergistic mechanisms between strain-induced polarization charges in piezoelectric nanowires and the caused change of carrier scattering in graphene. Compared to the conventional piezoelectric nanowire or graphene pressure sensors, this sensor is capable of measuring static pressures with a sensitivity of up to 9.4 × 10 -3 kPa -1 and a fast response time down to 5-7 ms. This demonstration of pressure sensors shows great potential in the applications of electronic skin and wearable devices.

  13. Calibrating airborne measurements of airspeed, pressure and temperature using a Doppler laser air-motion sensor

    Directory of Open Access Journals (Sweden)

    W. A. Cooper


    Full Text Available A new laser air-motion sensor measures the true airspeed with a standard uncertainty of less than 0.1 m s−1 and so reduces uncertainty in the measured component of the relative wind along the longitudinal axis of the aircraft to about the same level. The calculated pressure expected from that airspeed at the inlet of a pitot tube then provides a basis for calibrating the measurements of dynamic and static pressure, reducing standard uncertainty in those measurements to less than 0.3 hPa and the precision applicable to steady flight conditions to about 0.1 hPa. These improved measurements of pressure, combined with high-resolution measurements of geometric altitude from the global positioning system, then indicate (via integrations of the hydrostatic equation during climbs and descents that the offset and uncertainty in temperature measurement for one research aircraft are +0.3 ± 0.3 °C. For airspeed, pressure and temperature, these are significant reductions in uncertainty vs. those obtained from calibrations using standard techniques. Finally, it is shown that although the initial calibration of the measured static and dynamic pressures requires a measured temperature, once calibrated these measured pressures and the measurement of airspeed from the new laser air-motion sensor provide a measurement of temperature that does not depend on any other temperature sensor.

  14. Non-invasive assessment of arterial stiffness using oscillometric blood pressure measurement

    Directory of Open Access Journals (Sweden)

    Komine Hidehiko


    Full Text Available Abstract Background Arterial stiffness is a major contributor to cardiovascular diseases. Because current methods of measuring arterial stiffness are technically demanding, the purpose of this study was to develop a simple method of evaluating arterial stiffness using oscillometric blood pressure measurement. Methods Blood pressure was conventionally measured in the left upper arm of 173 individuals using an inflatable cuff. Using the time series of occlusive cuff pressure and the amplitudes of pulse oscillations, we calculated local slopes of the curve between the decreasing cuff pressure and corresponding arterial volume. Whole pressure-volume curve was derived from numerical integration of the local slopes. The curve was fitted using an equation and we identified a numerical coefficient of the equation as an index of arterial stiffness (Arterial Pressure-volume Index, API. We also measured brachial-ankle (baPWV PWV and carotid-femoral (cfPWV PWV using a vascular testing device and compared the values with API. Furthermore, we assessed carotid arterial compliance using ultrasound images to compare with API. Results The slope of the calculated pressure-volume curve was steeper for compliant (low baPWV or cfPWV than stiff (high baPWV or cfPWV arteries. API was related to baPWV (r = -0.53, P r = -0.49, P r = 0.32, P Conclusions These results suggest that our method can simply and simultaneously evaluate arterial stiffness and blood pressure based on oscillometric measurements of blood pressure.

  15. Non-invasive assessment of arterial stiffness using oscillometric blood pressure measurement (United States)


    Background Arterial stiffness is a major contributor to cardiovascular diseases. Because current methods of measuring arterial stiffness are technically demanding, the purpose of this study was to develop a simple method of evaluating arterial stiffness using oscillometric blood pressure measurement. Methods Blood pressure was conventionally measured in the left upper arm of 173 individuals using an inflatable cuff. Using the time series of occlusive cuff pressure and the amplitudes of pulse oscillations, we calculated local slopes of the curve between the decreasing cuff pressure and corresponding arterial volume. Whole pressure-volume curve was derived from numerical integration of the local slopes. The curve was fitted using an equation and we identified a numerical coefficient of the equation as an index of arterial stiffness (Arterial Pressure-volume Index, API). We also measured brachial-ankle (baPWV) PWV and carotid-femoral (cfPWV) PWV using a vascular testing device and compared the values with API. Furthermore, we assessed carotid arterial compliance using ultrasound images to compare with API. Results The slope of the calculated pressure-volume curve was steeper for compliant (low baPWV or cfPWV) than stiff (high baPWV or cfPWV) arteries. API was related to baPWV (r = -0.53, P blood pressure based on oscillometric measurements of blood pressure. PMID:22325084

  16. Non-invasive assessment of arterial stiffness using oscillometric blood pressure measurement. (United States)

    Komine, Hidehiko; Asai, Yoshiyuki; Yokoi, Takashi; Yoshizawa, Mutsuko


    Arterial stiffness is a major contributor to cardiovascular diseases. Because current methods of measuring arterial stiffness are technically demanding, the purpose of this study was to develop a simple method of evaluating arterial stiffness using oscillometric blood pressure measurement. Blood pressure was conventionally measured in the left upper arm of 173 individuals using an inflatable cuff. Using the time series of occlusive cuff pressure and the amplitudes of pulse oscillations, we calculated local slopes of the curve between the decreasing cuff pressure and corresponding arterial volume. Whole pressure-volume curve was derived from numerical integration of the local slopes. The curve was fitted using an equation and we identified a numerical coefficient of the equation as an index of arterial stiffness (Arterial Pressure-volume Index, API). We also measured brachial-ankle (baPWV) PWV and carotid-femoral (cfPWV) PWV using a vascular testing device and compared the values with API. Furthermore, we assessed carotid arterial compliance using ultrasound images to compare with API. The slope of the calculated pressure-volume curve was steeper for compliant (low baPWV or cfPWV) than stiff (high baPWV or cfPWV) arteries. API was related to baPWV (r = -0.53, P blood pressure based on oscillometric measurements of blood pressure.

  17. Clinical significance of home blood pressure measurements for the prevention and management of high blood pressure. (United States)

    Imai, Yutaka; Hosaka, Miki; Elnagar, Noha; Satoh, Michihiro


    1. Ambulatory blood pressure (ABP) monitoring (M) provides BP information at many points on any particular day during unrestricted routine daily activities, whereas home blood pressure (HBP) monitoring provides a lot of BP information obtained under fixed times and conditions over a long period of time, thus mean values of HBP provide high reproducibility, and thus an overall superiority compared with ABP.  2. HBP is at least equally or better able than ABP to predict hypertensive target organ damage and prognosis of cardiovascular disease.  3. HBPM allows for ongoing disease monitoring by patients, improves adherence to antihypertensive treatment, and can provide health-care providers with timely clinical data and direct and immediate feedback regarding diagnosis and treatment of hypertension.  4. HBPM provides BP information in relation to time; that is, BP in the morning, in the evening and at night during sleep, and it is an essential tool for the diagnosis of white-coat and masked hypertension.  5. HBPM yields minimal alerting affects and no or minimal placebo effect, and can therefore distinguish small, but significant, serial changes in BP. It is thus the most practical method for monitoring BP in the day-to-day management of hypertension. 6. The superiority of HBPM over ABPM and clinic BPM is apparent from almost all practical and clinical research perspectives. © 2013 Wiley Publishing Asia Pty Ltd.

  18. Enhanced performance of a wide-aperture copper vapour laser with ...

    Indian Academy of Sciences (India)


    Nov 27, 2015 ... A wide-aperture copper vapour laser was demonstrated at ∼ 10 kHz rep-rate with hydrogen additive in its buffer gas. Maximum power in excess of ∼ 50 W (at 10 kHz) was achieved by adding 1.96% hydrogen to the neon buffer gas at 20 mbar total gas pressure. This increase in output power was about ...

  19. Theoretical and experimental studies on freezing point depression and vapor pressure deficit as methods to measure osmotic pressure of aqueous polyethylene glycol and bovine serum albumin solutions. (United States)

    Kiyosawa, Keitaro


    For survival in adverse environments where there is drought, high salt concentration or low temperature, some plants seem to be able to synthesize biochemical compounds, including proteins, in response to changes in water activity or osmotic pressure. Measurement of the water activity or osmotic pressure of simple aqueous solutions has been based on freezing point depression or vapor pressure deficit. Measurement of the osmotic pressure of plants under water stress has been mainly based on vapor pressure deficit. However, differences have been noted for osmotic pressure values of aqueous polyethylene glycol (PEG) solutions measured by freezing point depression and vapor pressure deficit. For this paper, the physicochemical basis of freezing point depression and vapor pressure deficit were first examined theoretically and then, the osmotic pressure of aqueous ethylene glycol and of PEG solutions were measured by both freezing point depression and vapor pressure deficit in comparison with other aqueous solutions such as NaCl, KCl, CaCl(2), glucose, sucrose, raffinose, and bovine serum albumin (BSA) solutions. The results showed that: (1) freezing point depression and vapor pressure deficit share theoretically the same physicochemical basis; (2) theoretically, they are proportional to the molal concentration of the aqueous solutions to be measured; (3) in practice, the osmotic pressure levels of aqueous NaCl, KCl, CaCl(2), glucose, sucrose, and raffinose solutions increase in proportion to their molal concentrations and there is little inconsistency between those measured by freezing point depression and vapor pressure deficit; (4) the osmotic pressure levels of aqueous ethylene glycol and PEG solutions measured by freezing point depression differed from the values measured by vapor pressure deficit; (5) the osmotic pressure of aqueous BSA solution measured by freezing point depression differed slightly from that measured by vapor pressure deficit.

  20. Behaviour of carbon dioxide and water vapour flux densities from a disturbed raised peat bog

    NARCIS (Netherlands)

    Nieveen, J.P.; Jacobs, A.F.G.


    Measurements of carbon dioxide and water vapour flux densities were carried out for a disturbed raised peat bog in the north of the Netherlands during an 18 month continuous experiment. Tussock grass (sp. Molinea caerulae) mainly dominated the vegetation of the bog area. The maximum leaf area index

  1. Oil mist and vapour concentrations from drilling fluids: inter- and intra-laboratory comparison of chemical analyses. (United States)

    Galea, Karen S; Searl, Alison; Sánchez-Jiménez, Araceli; Woldbæk, Torill; Halgard, Kristin; Thorud, Syvert; Steinsvåg, Kjersti; Krüger, Kirsti; Maccalman, Laura; Cherrie, John W; van Tongeren, Martie


    There are no recognized analytical methods for measuring oil mist and vapours arising from drilling fluids used in offshore petroleum drilling industry. To inform the future development of improved methods of analysis for oil mist and vapours this study assessed the inter- and intra-laboratory variability in oil mist and vapour analysis. In addition, sample losses during transportation and storage were assessed. Replicate samples for oil mist and vapour were collected using the 37-mm Millipore closed cassette and charcoal tube assembly. Sampling was conducted in a simulated shale shaker room, similar to that found offshore for processing drilling fluids. Samples were analysed at two different laboratories, one in Norway and one in the UK. Oil mist samples were analysed using Fourier transform infrared spectroscopy (FTIR), while oil vapour samples were analysed by gas chromatography (GC). The comparison of replicate samples showed substantial within- and between-laboratory variability in reported oil mist concentrations. The variability in oil vapour results was considerably reduced compared to oil mist, provided that a common method of calibration and quantification was adopted. The study also showed that losses can occur during transportation and storage of samples. There is a need to develop a harmonized method for the quantification of oil mist on filter and oil vapour on charcoal supported by a suitable proficiency testing scheme for laboratories involved in the analysis of occupational hygiene samples for the petroleum industry. The uncertainties in oil mist and vapour measurement have substantial implications in relation to compliance with occupational exposure limits and also in the reliability of any exposure-response information reported in epidemiological studies.


    Energy Technology Data Exchange (ETDEWEB)

    Vinayak N. Kabadi


    It is well known that the fluid phase equilibria can be represented by a number of {gamma}-models , but unfortunately most of them do not function well under high temperature. In this calculation, we mainly investigate the performance of UNIQUAC and NRTL models under high temperature, using temperature dependent parameters rather than using the original formulas. the other feature of this calculation is that we try to relate the excess Gibbs energy G{sup E}and enthalpy of mixing H{sup E}simultaneously. In other words, we will use the high temperature and pressure G{sup E} and H{sup E}data to regress the temperature dependant parameters to find out which model and what kind of temperature dependant parameters should be used.

  3. More accurate systolic blood pressure measurement is required for improved hypertension management: a perspective. (United States)

    Nitzan, Meir; Slotki, Itzchak; Shavit, Linda


    The commonly used techniques for systolic blood pressure (SBP) and diastolic blood pressure (DBP) measurement are the auscultatory Korotkoff-based sphygmomanometry and oscillometry. The former technique is relatively accurate but is limited to a physician's office because its automatic variant is subject to noise artifacts. Consequently, the Korotkoff-based measurement overestimates the blood pressure in some patients due to white coat effect, and because it is a single measurement, it cannot properly represent the variable blood pressure. Automatic oscillometry can be used at home by the patient and is preferred even in clinics. However, the technique's accuracy is low and errors of 10-15 mmHg are common. Recently, we have developed an automatic technique for SBP measurement, based on an arm pressure cuff and a finger photoplethysmographic probe. The technique was found to be significantly more accurate than oscillometry, and comparable to the Korotkoff-based technique, the reference-standard for non-invasive blood pressure measurements. The measurement of SBP is a mainstay for the diagnosis and follow-up of hypertension, which is a major risk factor for several adverse events, mainly cardiovascular. Lowering blood pressure evidently reduces the risk, but excessive lowering can result in hypotension and consequently hypoperfusion to vital organs, since blood pressure is the driving force for blood flow. Erroneous measurement by 10 mmHg can lead to a similar unintended reduction of SBP and may adversely affect patients treated to an SBP of 120-130 mmHg. In particular, in elderly patients, unintended excessive reduction of blood pressure due to inaccurate SBP measurement can result in cerebral hypoperfusion and consequent cognitive decline. By using a more accurate technique for automatic SBP measurement (such as the photoplethysmographic-based technique), the optimal blood pressure target can be achieved with lower risk for hypotension and its adverse events.

  4. Upper tropospheric water vapour variability at high latitudes – Part 1: Influence of the annular modes

    Directory of Open Access Journals (Sweden)

    C. E. Sioris


    Full Text Available Seasonal and monthly zonal medians of water vapour in the upper troposphere and lower stratosphere (UTLS are calculated for both Atmospheric Chemistry Experiment (ACE instruments for the northern and southern high-latitude regions (60–90° N and 60–90° S. Chosen for the purpose of observing high-latitude processes, the ACE orbit provides sampling of both regions in 8 of 12 months of the year, with coverage in all seasons. The ACE water vapour sensors, namely MAESTRO (Measurements of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation and the Fourier Transform Spectrometer (ACE-FTS are currently the only satellite instruments that can probe from the lower stratosphere down to the mid-troposphere to study the vertical profile of the response of UTLS water vapour to the annular modes. The Arctic oscillation (AO, also known as the northern annular mode (NAM, explains 64 % (r = −0.80 of the monthly variability in water vapour at northern high latitudes observed by ACE-MAESTRO between 5 and 7 km using only winter months (January to March, 2004–2013. Using a seasonal time step and all seasons, 45 % of the variability is explained by the AO at 6.5 ± 0.5 km, similar to the 46 % value obtained for southern high latitudes at 7.5 ± 0.5 km explained by the Antarctic oscillation or southern annular mode (SAM. A large negative AO event in March 2013 produced the largest relative water vapour anomaly at 5.5 km (+70 % over the ACE record. A similarly large event in the 2010 boreal winter, which was the largest negative AO event in the record (1950–2015, led to > 50 % increases in water vapour observed by MAESTRO and ACE-FTS at 7.5 km.

  5. Non-destructive estimation of root pressure using sap flow, stem diameter measurements and mechanistic modelling. (United States)

    De Swaef, Tom; Hanssens, Jochen; Cornelis, Annelies; Steppe, Kathy


    Upward water movement in plants via the xylem is generally attributed to the cohesion-tension theory, as a response to transpiration. Under certain environmental conditions, root pressure can also contribute to upward xylem water flow. Although the occurrence of root pressure is widely recognized, ambiguity exists about the exact mechanism behind root pressure, the main influencing factors and the consequences of root pressure. In horticultural crops, such as tomato (Solanum lycopersicum), root pressure is thought to cause cells to burst, and to have an important impact on the marketable yield. Despite the challenges of root pressure research, progress in this area is limited, probably because of difficulties with direct measurement of root pressure, prompting the need for indirect and non-destructive measurement techniques. A new approach to allow non-destructive and non-invasive estimation of root pressure is presented, using continuous measurements of sap flow and stem diameter variation in tomato combined with a mechanistic flow and storage model, based on cohesion-tension principles. Transpiration-driven sap flow rates are typically inversely related to stem diameter changes; however, this inverse relationship was no longer valid under conditions of low transpiration. This decoupling between sap flow rates and stem diameter variations was mathematically related to root pressure. Root pressure can be estimated in a non-destructive, repeatable manner, using only external plant sensors and a mechanistic model.

  6. Multiplex pressure measurement in microsystems using volume displacement of particle suspensions. (United States)

    Chung, Kwanghun; Lee, Hyewon; Lu, Hang


    We demonstrate a simple image-based method to measure pressure in microsystems using volume displacement of fluorescent particle suspensions. These micro pressure-sensors are composed of two layers with a poly(dimethylsiloxane) (PDMS) membrane in between: the flow layer includes a flow channel and the sensor layer contains a detection channel filled with suspensions of fluorescent particles. The pressure increase in the flow channel deflects the membrane, and this membrane deformation can be quantified by measuring the cross-sectional areas at specific focal planes. These simple sensors have the advantage that a broad sensing-range can be achieved by tuning the mechanical property and the geometry of the membrane during design and fabrication, and even simpler by tuning the focal plane or the pressure of a reference chamber while in operation. We also demonstrate here a pressure transduction scheme coupled with the image-based sensing method as a multiplex pressure measurement tool for simultaneously detecting pressures in multiple locations in a microsystem. Overall, the image-based pressure sensing method has high precision when operated in both direct and remote detection modes. Compared to conventional mechanical methods of pressure detection, this technique is inexpensive because it does not require complex off-chip equipment to quantify the pressure-dependent membrane deformation. In addition, the image analysis using the software code developed here is fast, and it generates data that are simple to interpret.

  7. Measurement of blood pressure, ankle blood pressure and calculation of ankle brachial index in general practice

    DEFF Research Database (Denmark)

    Nexøe, Jørgen; Damsbo, Bent; Lund, Jens Otto


    BACKGROUND: Low ankle brachial index (ABI) is a sensitive measure of 'burden' of atherosclerosis, indicating cardiovascular risk of the asymptomatic patient. Conventionally, ABI values......BACKGROUND: Low ankle brachial index (ABI) is a sensitive measure of 'burden' of atherosclerosis, indicating cardiovascular risk of the asymptomatic patient. Conventionally, ABI values...

  8. Respiratory modulation of oscillometric cuff pressure pulses and Korotkoff sounds during clinical blood pressure measurement in healthy adults. (United States)

    Chen, Diliang; Chen, Fei; Murray, Alan; Zheng, Dingchang


    Accurate blood pressure (BP) measurement depends on the reliability of oscillometric cuff pressure pulses (OscP) and Korotkoff sounds (KorS) for automated oscillometric and manual techniques. It has been widely accepted that respiration is one of the main factors affecting BP measurement. However, little is known about how respiration affects the signals from which BP measurement is obtained. The aim was to quantify the modulation effect of respiration on oscillometric pulses and KorS during clinical BP measurement. Systolic and diastolic BPs were measured manually from 40 healthy subjects (from 23 to 65 years old) under normal and regular deep breathing. The following signals were digitally recorded during linear cuff deflation: chest motion from a magnetometer to obtain reference respiration, cuff pressure from an electronic pressure sensor to derive OscP, and KorS from a digital stethoscope. The effects of respiration on both OscP and KorS were determined from changes in their amplitude associated with respiration between systole and diastole. These changes were normalized to the mean signal amplitude of OscP and KorS to derive the respiratory modulation depth. Reference respiration frequency, and the frequencies derived from the amplitude modulation of OscP and KorS were also calculated and compared. Respiratory modulation depth was 14 and 40 % for OscP and KorS respectively under normal breathing condition, with significant increases (both p  0.05) during deep breathing, and for the oscillometric signal during normal breathing (p > 0.05). Our study confirmed and quantified the respiratory modulation effect on the oscillometric pulses and KorS during clinical BP measurement, with increased modulation depth under regular deeper breathing.

  9. PIV-based pressure, force, and torque measurements of a robotic model swimmer (United States)

    Dabiri, John; Lucas, Kelsey; Thornycroft, Patrick; Lauder, George


    We apply a recently developed technique for non-invasive pressure measurement to study the dynamics of anguilliform swimming by a robotic flapping foil. The method is based on spatial integration of time-resolved particle image velocimetry measurements. The pressure gradient computed from the Navier-Stokes equations is integrated along multiple paths in the domain, and the local pressure is determined by the median value of the integration results. In addition, the pressure field is integrated on the surface of the foil to compute the instantaneous forces and torque exerted by the foil on the fluid. Direct force and torque measurements from a load cell are used to confirm the accuracy of the PIV-based measurements. Results for flapping foils of varying flexibility are compared to infer the role of the pressure field in the dynamics and energetic efficiency of locomotion.

  10. A novel non-invasive blood pressure waveform measuring system compared to Millar applanation tonometry. (United States)

    Földi, Sándor; Horváth, Tamás; Zieger, Flóra; Sótonyi, Péter; Cserey, György


    The accurate, non-invasive, measuring of the continuous arterial blood pressure waveform faces some difficulties and an innovative blood pressure measurement technology is urgently needed. However, the arterial blood pressure waveform plays an essential role in health care by providing diagnostic information and base for calculating several heart function parameters. The aim of this study is to introduce a novel non-invasive measuring system that can measure the arterial blood pressure waveform with high accuracy in comparison to an applanation tonometry system. The applied measuring device utilizes a new measurement strategy enabled by the OptoForce 3D force sensor, which is attached to the wrist at the radial artery. To validate the accuracy, 30 simultaneous measurements were taken with a Millar tonometer. For the simultaneously recorded non-invasive signals, the similarity was high (the average correlation was [Formula: see text]). The differences in the systolic and the diastolic blood pressure measured by the two systems are small. The average differences ([Formula: see text]) for simultaneously recorded systolic, diastolic, mean arterial and incisura pressures were: [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], respectively. These results satisfy the AAMI criteria. Based on our results, this new system requires further development and validation against invasive arterial blood pressure monitoring in order to prove its usefulness in patient monitoring, emergency care, and pulse diagnosis.

  11. A series of self-measurements by the patient is a reliable alternative to ambulatory blood pressure measurement

    NARCIS (Netherlands)

    Brueren, M. M.; Schouten, H. J.; de Leeuw, P. W.; van Montfrans, G. A.; van Ree, J. W.


    Several studies have reported overdiagnosis and overtreatment of hypertensive patients, especially in borderline hypertensives. To find a blood pressure measurement procedure that reduces the risk of misclassification to an acceptable level. Comparative, prospective study over seven months of

  12. Treatment of hypertension based on measurement of blood pressure variability: lessons from animal studies. (United States)

    Su, Ding-Feng


    Blood pressure variability, a quantitative index for the spontaneous variation in blood pressure, has been proposed as a risk factor for end-organ damage and to determine the efficacy of hypertension treatment. Animal studies indicate that blood pressure variability is as important as blood pressure level in determining end-organ damage, and that high blood pressure variability is associated with end-organ damage, including myocardial lesions, aortic hypertrophy, vascular remodeling and renal damage. Although the organ damage induced by high blood pressure variability was similar to that induced by hypertension, comparative studies in sinoaortic-denervated and spontaneously hypertensive rats revealed that aortic hypertrophy is a sensitive index of high blood pressure variability, and left ventricular hypertrophy is a sensitive index of high blood pressure level. The possible mechanisms for high blood pressure variability-induced end-organ damage include: direct endothelial lesions, renin-angiotensin system activation, inflammation initiation and cardiomyocyte apoptosis augmentation. Blood pressure variability reduction contributes importantly to the organ-protective effect of some antihypertensive drugs. Although animal studies suggest some advantages in blood pressure variability measurements, clinical trials are necessary before the widespread use of blood pressure variability as a predictor of hypertensive organ damage and a new strategy for the treatment of hypertension.

  13. Proportion and characteristics of patients who measure their blood pressure at home: Nationwide survey in Slovenia

    Directory of Open Access Journals (Sweden)

    Petek-Šter Marija


    Full Text Available Introduction. Home blood pressure monitoring has several advantages over blood pressure monitoring at a physician's office, and has become a useful instrument in the management of hypertension. Objective. To explore the rate and characteristics of patients who measure their blood pressure at home. Methods. A sample of 2,752 patients with diagnosis of essential arterial hypertension was selected from 12596 consecutive office visitors. Data of 2,639 patients was appropriate for analysis. The data concerning home blood pressure measurement and patients' characteristics were obtained from the patients' case histories. Results 1,835 (69.5% out of 2,639 patients measured their blood pressure at home. 1,284 (70.0% of home blood pressure patients had their own blood pressure measurement device. There were some important differences between these two groups: home blood pressure patients were more frequently male, of younger age, better educated, from urban area, mostly non-smokers, more likely to have diabetes mellitus and ischemic heart disease and had higher number of co-morbidities and were on other drugs beside antihypertensive medication. Using the logistic regression analysis we found that the most powerful predictors of home blood pressure monitoring had higher education level than primary school OR=1.80 (95% CI 1.37-2.37, non-smoking OR=2.16 (95% CI 1.40-3.33 and having a physician in urban area OR=1.32 (95% CI 1.02-1.71. Conclusion. Home blood pressure monitoring is popular in Slovenia. Patients who measured blood pressure at home were different from patients who did not. Younger age, higher education, non-smoking, having a physician in urban area and longer duration of hypertension were predictors of home blood pressure monitoring.

  14. Liquid sinusoidal pressure measurement by laser interferometry based on the refractive index of water. (United States)

    Yang, Jun; Fan, Shangchun; Li, Cheng; Guo, Zhanshe; Li, Bo; Shi, Bo


    A new method with laser interferometry is used to enhance the traceability for sinusoidal pressure calibration in water. The laser vibrometer measures the dynamic pressure based on the acousto-optic effect. The relation of the refractive index of water and the optical path length with the pressure's change is built based on the Lorentz-Lorenz equation, and the conversion coefficients are tested by static calibration in situ. A device with a piezoelectric transducer and resonant pressure pipe with water is set up to generate sinusoidal pressure up to 20 kHz. With the conversion coefficients, the reference sinusoidal pressure is measured by the laser interferometer for pressure sensors' dynamic calibration. The experiment results show that under 10 kHz, the measurement results between the laser vibrometer and a piezoelectric sensor are in basic agreement and indicate that this new method and its measurement system are feasible in sinusoidal pressure calibration. Some disturbing components including small amplitude, temperature change, pressure maldistribution, and glass windows' vibration are also analyzed, especially for the dynamic calibrations above 10 kHz.

  15. Home blood pressure in children and adolescents: a comparison with office and ambulatory blood pressure measurements. (United States)

    Salgado, Cláudia Maria; Jardim, Paulo César Brandão Veiga; Viana, Jackeline Karoline Brito; Jardim, Thiago de Souza Veiga; Velasquez, Paola Patrícia Castillo


    To compare BP measurements of children and adolescents using different methods office BP (OBP), ambulatory BP monitoring (ABPM) and home BP measurement (HBPM) and to study their correlations. Individuals were evaluated between 5 and 15 years of age who had been referred because of a previous high BP. OBP was measured with the OMRON-705CP. Three measurements were carried out at 5-min intervals. HBPM were taken using the same device, two measurements at 5-min intervals in the morning and in the evening during 7 days. ABPM was performed using the SpaceLabs 90207 monitors. A total of 109 children and adolescents were evaluated (9.82 ± 2.63 years), 52.3% boys, 56.9% non-white. The office systolic BP (SBP) was lower than in daytime ABPM (p office diastolic BP (DBP) was lower than daytime ABPM (p home readings (SBP r = 0.731 and DBP r = 0.616) than with office's readings (SBP r = 0.653 and DBP r = 0.394). The BP of children and adolescents varies depending on the place and manner of measurement. ABPM presents better correlation with HBPM than with the office measurements. © 2011 The Author(s)/Acta Paediatrica © 2011 Foundation Acta Paediatrica.

  16. The mean machine; accurate non-invasive blood pressure measurement in the critically ill patient. (United States)

    Muecke, Sandy; Bersten, Andrew; Plummer, John


    Accurate indirect prehospital blood pressure measurement in the critically ill patient remains an important challenge to both patient management and prehospital research. Ambulatory blood pressure measuring devices have not been trialled for prehospital use in critically ill patients. Prior to prehospital validation where conditions are suboptimal, we aimed to test under favourable conditions in the Intensive Care Unit, a selection of ambulatory devices that may be suitable for use in the field. Systolic, diastolic and mean pressures of three ambulatory devices were compared to the average of 1 min of independently recorded, high fidelity intra-arterial reference pressures. Eighteen critically ill patients were recruited. Device performance was required to fulfil the Association for the Advancement of Medical Instrumentation (AAMI) protocol. Additionally, agreement between measurement methods was examined using Bland-Altman plots. Two-level linear mixed model analyses were under- taken. For each device, 150 paired measurements (arterial reference and device) were analysed. According to the AAMI protocol, no device measured systolic pressures accurately. One device measured diastolic pressures accurately. Integrated mean pressures were accurately measured by all devices. Overall, SunTech Medical's Oscar 2 performed best with mean pressure error not exceeding 17 mmHg. For this device, Bland-Altman plots showed uniform agreement across a wide range of mean pressures. Two-level linear mixed effects analyses showed that Oscar 2 mean error reduced during vasopressor use by (-) 3.9 mmHg (95% CI -5.9, -1.9; P tension. In the Intensive Care Unit, the performance of one device, the Oscar 2, surpassed the others and fulfilled the AAMI protocol criteria for mean pressure measurement. This device is suitable for prehospital validation.

  17. Dynamic Temperature and Pressure Measurements in the Core of a Propulsion Engine (United States)

    Schuster, Bill; Gordon, Grant; Hultgren, Lennart S.


    Dynamic temperature and pressure measurements were made in the core of a TECH977 propulsion engine as part of a NASA funded investigation into indirect combustion noise. Dynamic temperature measurements were made in the combustor, the inter-turbine duct, and the mixer using ten two-wire thermocouple probes. Internal dynamic pressure measurements were made at the same locations using piezoresistive transducers installed in semi-infinite coils. Measurements were acquired at four steady state operating conditions covering the range of aircraft approach power settings. Fluctuating gas temperature spectra were computed from the thermocouple probe voltage measurements using a compensation procedure that was developed under previous NASA test programs. A database of simultaneously acquired dynamic temperature and dynamic pressure measurements was produced. Spectral and cross-spectral analyses were conducted to explore the characteristics of the temperature and pressure fluctuations inside the engine, with a particular focus on attempting to identify the presence of indirect combustion noise.

  18. Evaluation of oscillometric and Doppler ultrasonic devices for blood pressure measurements in anesthetized and conscious dogs. (United States)

    Vachon, Catherine; Belanger, Marie C; Burns, Patrick M


    Two non-invasive blood pressure (NIBP) devices (oscillometry and Doppler) were compared to invasive blood pressure using a Bland-Altman analysis, in anesthetized and conscious dogs. When considering the systolic arterial pressure only during general anesthesia, both NIBP devices slightly underestimated the systolic arterial blood pressure however the precision and the limits of agreement for the Doppler were of a greater magnitude. This indicates a worse clinical performance by the Doppler. The performance of both NIBP devices deteriorated as measured in conscious animals. In general, for the oscillometric device, determination of invasive diastolic and mean arterial pressures was better than the invasive systolic arterial pressure. Overall, the oscillometric device satisfied more of the criteria set by the American College of Veterinary Internal Medicine consensus statement. Based upon these results, the oscillometric device is more reliable than the Doppler in the determination of blood pressure in healthy medium to large breed dogs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. A pitfall in the measurement of arterial blood pressure in the ischaemic limb during elevation

    DEFF Research Database (Denmark)

    Bülow, J; Jelnes, Rolf


    In order to evaluate if elevation of the ischaemic limb above heart level is an alternative to the conventionally applied method with external counterpressure for estimation of skin perfusion pressure, femoral and popliteal artery pressures were measured directly in eight patients with occlusion...... arterial pressure decreased only by 20% of the value expected from the degree of elevation of the calf above the level of the heart. Thus, it could be calculated that calf vascular resistance increased two- to three-fold on average during elevation. Four patients were reexamined with the venous pressure...... kept at 10 mmHg during elevation. In these patients, the increase in vascular resistance was significantly less compared with the situation in which venous pressure was 0 mmHg during elevation. The arterial pressure still did not decrease. It is concluded that perfusion pressure in the ischaemic lower...

  20. Modelling and interpreting the isotopic composition of water vapour in convective updrafts

    Directory of Open Access Journals (Sweden)

    M. Bolot


    Full Text Available The isotopic compositions of water vapour and its condensates have long been used as tracers of the global hydrological cycle, but may also be useful for understanding processes within individual convective clouds. We review here the representation of processes that alter water isotopic compositions during processing of air in convective updrafts and present a unified model for water vapour isotopic evolution within undiluted deep convective cores, with a special focus on the out-of-equilibrium conditions of mixed-phase zones where metastable liquid water and ice coexist. We use our model to show that a combination of water isotopologue measurements can constrain critical convective parameters, including degree of supersaturation, supercooled water content and glaciation temperature. Important isotopic processes in updrafts include kinetic effects that are a consequence of diffusive growth or decay of cloud particles within a supersaturated or subsaturated environment; isotopic re-equilibration between vapour and supercooled droplets, which buffers isotopic distillation; and differing mechanisms of glaciation (droplet freezing vs. the Wegener–Bergeron–Findeisen process. As all of these processes are related to updraft strength, particle size distribution and the retention of supercooled water, isotopic measurements can serve as a probe of in-cloud conditions of importance to convective processes. We study the sensitivity of the profile of water vapour isotopic composition to differing model assumptions and show how measurements of isotopic composition at cloud base and cloud top alone may be sufficient to retrieve key cloud parameters.

  1. Femoral artery pressure measurement to predict the outcome of arterial surgery in patients with multilevel disease

    DEFF Research Database (Denmark)

    Faris, I; Tønnesen, K H; Agerskov, K


    Direct measurement of the femoral artery pressure before operation has been used to predict the postoperative change in ankle and toe pressure in 102 limbs (83 patients) that underwent aortoiliac surgery for the treatment of atherosclerotic occlusion or stenosis affecting both the aortoiliac...... 25 mm Hg was associated with a high probability that amputation would be required. The chances of an amputation were less than 3% if a toe pressure higher than 40 mm Hg was predicted. If the predicted ankle pressure index was lower than 0.56, there was a 90% chance that intermittent claudication...... would persist. Measurement of the femoral artery pressure allows prediction of the toe and ankle pressure response to surgery to be made with sufficient accuracy to permit a preoperative decision to be made between the need for a single-level or a two-level arterial reconstruction: no patients who had...

  2. A novel three-jet microreactor for localized metal-organic chemical vapour deposition of gallium arsenide : Design and simulation

    NARCIS (Netherlands)

    Konakov, S.A.; Krzhizhanovskaya, V.V.


    We present a novel three-jet microreactor design for localized deposition of gallium arsenide (GaAs) by low-pressure Metal-Organic Chemical Vapour Deposition (MOCVD) for semiconductor devices, microelectronics and solar cells. Our approach is advantageous compared to the standard lithography and

  3. Corrosion resistant coatings (Al@#2@#O@#3@#) produced by metal-organic chemical vapour deposition using ATSB

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Haanappel, V.A.C.; van Corbach, H.D.; Fransen, T.; Gellings, P.J.


    The metal organic chemical vapour deposition (MOCVD) of amorphous alumina films on steel was performed in nitrogen at atmospheric pressure. This MOCVD process is based on the thermal decomposition of aluminium-tri-sec-butoxide (ATSB). The effect of the deposition temperature (within the range


    Directory of Open Access Journals (Sweden)

    V. G. Zhekul


    Full Text Available Purpose. Investigations of the characteristics of pressure waves presuppose the registration of the total profile of the pressure wave at a given point in space. For these purposes, various types of «pressure to the electrical signal» transmitters (sensors are used. Most of the common sensors are unsuitable for measuring the pulse pressure in a closed water volume at high hydrostatic pressures, in particular to study the effect of a powerful high-voltage pulse discharge on increasing the inflow of minerals and drinking water in wells. The purpose of the work was to develop antijamming piezoelectric waveguide sensor for measuring pulse pressure at a close distance from a high-voltage discharge channel in a closed volume of a liquid. Methodology. We have applied the calibration method as used as a secondary standard, the theory of electrical circuits. Results. We have selected the design and the circuit solution of the waveguide pressure sensor. We have developed a waveguide pulse-pressure sensor DTX-1 with a measuring loop. This sensor makes it possible to study the spectral characteristics of pressure waves of high-voltage pulse discharge in closed volumes of liquid at a hydrostatic pressure of up to 20 MPa and a temperature of up to 80 °C. The sensor can be used to study pressure waves with a maximum amplitude value of up to 150 MPa and duration of up to 80 µs. According to the results of the calibration, the sensitivity of the developed sensor DTX-1 with a measuring loop is 0.0346 V/MPa. Originality. We have further developed the theory of designing the waveguide piezoelectric pulse pressure sensors for measuring the pulse pressure at a close distance from a high-voltage discharge channel in a closed fluid volume by controlling the attenuation of the amplitude of the pressure signal. Practical value. We have developed, created, calibrated, used in scientific research waveguide pressure pulse sensors DTX-1. We propose sensors DTX-1 for sale

  5. A new method to measure Bowen ratios using high-resolution vertical dry and wet bulb temperature profiles

    NARCIS (Netherlands)

    Euser, T.; Luxemburg, W.M.J.; Everson, C.S.; Mengistu, M.G.; Clulow, A.D.; Bastiaanssen, W.G.M.


    The Bowen ratio surface energy balance method is a relatively simple method to determine the latent heat flux and the actual land surface evaporation. The Bowen ratio method is based on the measurement of air temperature and vapour pressure gradients. If these measurements are performed at only two

  6. Embedded optical probes for simultaneous pressure and temperature measurement of materials in extreme conditions (United States)

    Sandberg, R. L.; Rodriguez, G.; Gibson, L. L.; Dattelbaum, D. M.; Stevens, G. D.; Grover, M.; Lalone, B. M.; Udd, E.


    We present recent efforts at Los Alamos National Laboratory (LANL) to develop sensors for simultaneous, in situ pressure and temperature measurements under dynamic conditions by using an all-optical fiber-based approach. While similar tests have been done previously in deflagration-to-detonation tests (DDT), where pressure and temperature were measured to 82 kbar and 400°C simultaneously, here we demonstrate the use of embedded fiber grating sensors to obtain high temporal resolution, in situ pressure measurements in inert materials. We present two experimental demonstrations of pressure measurements: (1) under precise shock loading from a gas-gun driven plate impact and (2) under high explosive driven shock in a water filled vessel. The system capitalizes on existing telecom components and fast transient digitizing recording technology. It operates as a relatively inexpensive embedded probe (single-mode 1550 nm fiber-based Bragg grating) that provides a continuous fast pressure record during shock and/or detonation. By applying well-controlled shock wave pressure profiles to these inert materials, we study the dynamic pressure response of embedded fiber Bragg gratings to extract pressure amplitude of the shock wave and compare our results with particle velocity wave profiles measured simultaneously.

  7. Reproduction of pressure field in ultrasonic-measurement-integrated simulation of blood flow. (United States)

    Funamoto, Kenichi; Hayase, Toshiyuki


    Ultrasonic-measurement-integrated (UMI) simulation of blood flow is used to analyze the velocity and pressure fields by applying feedback signals of artificial body forces based on differences of Doppler velocities between ultrasonic measurement and numerical simulation. Previous studies have revealed that UMI simulation accurately reproduces the velocity field of a target blood flow, but that the reproducibility of the pressure field is not necessarily satisfactory. In the present study, the reproduction of the pressure field by UMI simulation was investigated. The effect of feedback on the pressure field was first examined by theoretical analysis, and a pressure compensation method was devised. When the divergence of the feedback force vector was not zero, it influenced the pressure field in the UMI simulation while improving the computational accuracy of the velocity field. Hence, the correct pressure was estimated by adding pressure compensation to remove the deteriorating effect of the feedback. A numerical experiment was conducted dealing with the reproduction of a synthetic three-dimensional steady flow in a thoracic aneurysm to validate results of the theoretical analysis and the proposed pressure compensation method. The ability of the UMI simulation to reproduce the pressure field deteriorated with a large feedback gain. However, by properly compensating the effects of the feedback signals on the pressure, the error in the pressure field was reduced, exhibiting improvement of the computational accuracy. It is thus concluded that the UMI simulation with pressure compensation allows for the reproduction of both velocity and pressure fields of blood flow. Copyright © 2012 John Wiley & Sons, Ltd.

  8. A method for extracting respiratory frequency during blood pressure measurement, from oscillometric cuff pressure pulses and Korotkoff sounds recorded during the measurement. (United States)

    Diliang Chen; Fei Chen; Murray, Alan; Dingchang Zheng


    Respiratory frequency is an important physiological feature commonly used to assess health. However, the current measurements involve dedicated devices which not only increase the medical cost but also make health monitoring inconvenient. Earlier studies have shown that respiratory frequency could be extracted from electrocardiography (ECG) signal, but little was done to assess the possibility of extracting respiratory frequency from oscillometric cuff pressure pulses (OscP) or Korotkoff sounds (KorS), which are normally used for measuring blood pressure and more easily accessible than the ECG signal. This study presented a method to extract respiratory frequency from OscP and KorS during clinical blood pressure measurement. The method was evaluated with clinical data collected from 15 healthy participants, and its measurement accuracy was compared with a reference respiratory rate obtained with a magnetometer. Experimental results showed small non-significant mean absolute bias (0.019 Hz for OscP and 0.024 Hz for KorS) and high correlation (0.7 for both OscP and KorS) between the reference respiratory frequency and respiratory frequency extracted from OscP or KorS, indicating the high reliability of extracting respiratory frequency from OscP and KorS during normal blood pressure measurement.

  9. A practical and reliable method of measuring blood pressure in the neonate by pulse oximetry. (United States)

    Langbaum, M; Eyal, F G


    We investigated the reliability of the plethysmographic waveform of the pulse oximeter to measure systolic blood pressure in sick neonates. Fifty infants admitted to the neonatal intensive care unit, with indwelling arterial catheters placed for their ongoing care, were enrolled. Median gestational age was 31 weeks (range, 24 to 40 weeks), and the mean birth weight was 1711 gm (range, 546 to 3856 gm). Blood pressure was recorded by an oscillometric method as well as from a transducer connected to an arterial catheter. Additionally, pulse oximeter blood pressures were obtained by gradually inflating an appropriately sized blood pressure cuff in increments of 2 to 5 mm Hg, on the same extremity as the oximeter probe, until the waveform just disappeared. The cuff was then rapidly inflated another 20 mm Hg and then gradually deflated in increments of 2 to 5 mm Hg until the waveform reappeared on the oximeter screen display. The pulse oximeter blood pressures were calculated both as the blood pressure noted at disappearance of the pulse oximeter waveform and as the blood pressure noted by the average pulse oximeter blood pressure at the disappearance and reappearance of the waveform. The mean intraarterial systolic blood pressure was 54 mm Hg (range, 36 to 82 mm Hg). Blood pressures obtained by pulse oximetry showed a significantly better correlation with intraarterial measurements in comparison with those obtained by oscillometric instruments. Additionally, the limits of agreement (mean difference +/- 2 SD) between blood pressures obtained by intraarterial measurements and those obtained by pulse oximetry were within a clinically acceptable range as opposed to those obtained by the comparison of intraarterial and oscillometric methods. Measurements of blood pressure in the neonate by means of pulse oximetry waveform analysis are easily obtainable and more accurate than those obtained by the oscillometric method.

  10. Characterizing the dynamic property of the vortex tail in a gas cyclone by wall pressure measurements

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Cuizhi; Sun, Guogang; Dong, Ruiqian; Fu, Shuangcheng [State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing, 102249 (China)


    To explore a determination method for cyclone vortex tail, the wall pressures at different axial and radial positions of a cylinder-on-cone cyclone were measured and analyzed by the Fast Fourier Transform (FFT) and probability density analyses in this paper. The cyclone vortex tail was also visualized by a red ink tracer. The results show that the cyclone wall pressure does not change in the cylindrical section and gradually decreases in the conical section. The magnitudes of wall pressure at different azimuths are almost identical, indicating an axisymmetrical wall pressure radial profile in these parts of the cyclone. Whereas in the lower part of the cone and/or the upper part of dipleg, there is a sudden fall of wall pressure and non-axisymmetrical pressure radial profile. The minimum wall pressure occurs at about 270 azimuth in this region. Underneath in the next part of the dipleg, the wall pressure rapidly rises and returns to axisymmetry. These characteristics indicate that the vortex tail is bended to wall, turns around in this region, and can be used as evidences of the vortex tail. The position determined by the pressure measurement is close to the position of the rotating ring observed in the tracing experiment. It is also found that the frequency of the inner vortex is different from that of the outer vortex. The inner vortex flow fluctuates stronger and faster than its outer partner. At the vortex tail zone, the vortex breaks and the inner vortex fluctuation is involved in the wall pressure signal. Therefore, the position and dynamic property of the vortex tail can be well identified from the wall pressure measurement. The pressure measurement could provide some solid experimental basis for assessing relations of natural vortex length. (author)

  11. Pressure Regulator With Internal Ejector Circulation Pump, Flow and Pressure Measurement Porting, and Fuel Cell System Integration Options (United States)

    Vasquez, Arturo


    An advanced reactant pressure regulator with an internal ejector reactant circulation pump has been developed to support NASA's future fuel cell power systems needs. These needs include reliable and safe operation in variable-gravity environments, and for exploration activities with both manned and un manned vehicles. This product was developed for use in Proton Exchange Membrane Fuel Cell (PEMFC) power plant reactant circulation systems, but the design could also be applied to other fuel cell system types, (e.g., solid-oxide or alkaline) or for other gas pressure regulation and circulation needs. The regulator design includes porting for measurement of flow and pressure at key points in the system, and also includes several fuel cell system integration options. NASA has recognized ejectors as a viable alternative to mechanical pumps for use in spacecraft fuel cell power systems. The ejector motive force is provided by a variable, high-pressure supply gas that travels through the ejector s jet nozzle, whereby the pressure energy of the fluid stream is converted to kinetic energy in the gas jet. The ejector can produce circulation-to-consumption-flow ratios that are relatively high (2-3 times), and this phenomenon can potentially (with proper consideration of the remainder of the fuel cell system s design) be used to provide completely for reactant pre-humidification and product water removal in a fuel cell system. Specifically, a custom pressure regulator has been developed that includes: (1) an ejector reactant circulation pump (with interchangeable jet nozzles and mixer sections, gas-tight sliding and static seals in required locations, and internal fluid porting for pressure-sensing at the regulator's control elements) and (2) internal fluid porting to allow for flow rate and system pressure measurements. The fluid porting also allows for inclusion of purge, relief, and vacuum-breaker check valves on the regulator assembly. In addition, this regulator could also

  12. Standing orthostatic blood pressure measurements cannot be replaced by sitting measurements. (United States)

    Breeuwsma, Anna C; Hartog, Laura C; Kamper, Adriaan M; Groenier, Klaas H; Bilo, Henk Jg; Kleefstra, Nanne; Van Hateren, Kornelis Jj


    As many elderly patients are not able to stand for several minutes, sitting orthostatic blood pressure (BP) measurements are sometimes used as an alternative. We aimed to investigate the difference in BP response and orthostatic hypotension (OH) prevalence between the standard postural change to the sitting and the standing position in a cross-sectional observational study. BP was measured with a continuous BP measurement device during two postural changes, from supine to the sitting and from supine to the standing position. Linear mixed models were used to investigate the differences in changes (Δ) of systolic BP (SBP) and diastolic BP (DBP) between the two postural changes. The prevalence and the positive and negative proportions of agreement of OH were calculated of the two postural changes. One hundred and four patients with a mean age of 69 years were included. ΔSBP was significantly larger in the standing position compared with the sitting between 0 and 44 s. ΔDBP was significantly larger in the sitting position compared with the standing 75-224 s after postural change. The prevalence of OH was 66.3% (95% confidence interval (CI) 57.2, 75.4) in the standing position and 67.3% (95% CI 58.3, 76.3) in the sitting position. The positive proportion of agreement was 74.8% and the negative proportion of agreement was 49.3%. A clear difference was seen in BP response between the two postural changes. Although no significant difference in prevalence of OH was observed, the positive and negative proportion of agreement of the prevalence of OH were poor to moderate, which indicates a different outcome between both postural changes.

  13. Pressure-Decay Measurements Improve Bubble-Point Test (United States)

    Silkey, J. S.; Orton, G. F.


    Technique reduces by factor of about 100 minimum detectable flaw size in bubble-point test. By measuring rate of slow leakage, flaws as small as about 10-4 in. 2 (0.06mm2) are detected. Since technique does not require observation of screen, tests run on screens already installed inside tanks and pipes.

  14. Comparison of current tonometry techniques in measurement of intraocular pressure

    Directory of Open Access Journals (Sweden)

    Behrooz Kouchaki


    Conclusion: Although the mean difference of measured IOP by NCT, DCT, and ORA with GAT was less than 2 mmHg, the limit of agreement was relatively large. CCT and CRF were important influencing factors in the four types of tonometers.

  15. Non-invasive measurement of pressure gradients using ultrasound

    DEFF Research Database (Denmark)

    Olesen, Jacob Bjerring; Traberg, Marie Sand; Pihl, Michael Johannes


    for isotropic fluids to the estimated velocity fields. The velocity fields were measured for a steady flow on a carotid bifurcation phantom (Shelley Medical, Canada) with a 70% constriction on the internal branch. Scanning was performed with a BK8670 linear transducer (BK Medical, Denmark) connected to a BK...

  16. Clinical aviation medicine research : comparison of simultaneous measurements of intra-aortic and auscultatory blood pressures with pressure-flow dynamics during rest and excercise. (United States)


    The study provides correlative information with respect to the comparative accuracy of the traditional 'cuff' clinical method of obtaining blood pressure and the laboratory catheterization procedure which measures actual blood pressure. The informati...

  17. Study and mitigation of calibration error sources in a water vapour Raman lidar (United States)

    David, Leslie; Bock, Olivier; Bosser, Pierre; Thom, Christian; Pelon, Jacques


    The monitoring of water vapour throughout the atmosphere is important for many scientific applications (weather forecasting, climate research, calibration of GNSS altimetry measurements). Measuring water vapour remains a technical challenge because of its high variability in space and time. The major issues are achieving long-term stability (e.g., for climate trends monitoring) and high accuracy (e.g. for calibration/validation applications). LAREG and LOEMI at Institut National de l'Information Géographique et Forestière (IGN) have developed a mobile scanning water vapour Raman lidar in collaboration with LATMOS at CNRS. This system aims at providing high accuracy water vapour measurements throughout the troposphere for calibrating GNSS wet delay signals and thus improving vertical positioning. Current developments aim at improving the calibration method and long term stability of the system to allow the Raman lidar to be used as a reference instrument. The IGN-LATMOS lidar was deployed in the DEMEVAP (Development of Methodologies for Water Vapour Measurement) campaign that took place in 2011 at the Observatoire de Haute Provence. The goals of DEMEVAP were to inter-compare different water vapour sounding techniques (lidars, operational and research radiosondes, GPS,…) and to study various calibration methods for the Raman lidar. A significant decrease of the signals and of the calibration constants of the IGN-LATMOS Raman lidar has been noticed all along the campaign. This led us to study the likely sources of uncertainty and drifts in each part of the instrument: emission, reception and detection. We inventoried several error sources as well as instability sources. The impact of the temperature dependence of the Raman lines on the filter transmission or the fluorescence in the fibre, are examples of the error sources. We investigated each error source and each instability source (uncontrolled laser beam jitter, temporal fluctuations of the photomultiplier

  18. Corneal biomechanical properties and intraocular pressure measurement in Marfan patients. (United States)

    Kara, Necip; Bozkurt, Ercument; Baz, Okkes; Altinkaynak, Hasan; Dundar, Huseyin; Yuksel, Kemal; Yazici, Ahmet Taylan; Demirok, Ahmet; Candan, Sukru


    To compare the biomechanical properties of the cornea and intraocular pressure (IOP) between patients with Marfan syndrome and age-matched controls. Departments of Ophthalmology and Genetics, Bakirkoy Maternity and Children Diseases Hospital, and Beyoglu Eye Education and Research Hospital, Istanbul, Turkey. Cross-sectional study. This study comprised patients with Marfan syndrome (study group) and healthy individuals (control group). The study group was subdivided into patients with ectopia lentis and patients without ectopia lentis. In the right eye of each patient, the corneal hysteresis (CH), corneal resistance factor (CRF), Goldman-correlated IOP, and corneal-compensated IOP were recorded. Overall, the mean CH, CRF, Goldman-correlated IOP, and corneal-compensated IOP were not significantly different between the study group and the control group. The mean CH was 9.9 mm Hg ± 1.2 (SD) in study eyes with ectopia lentis and 11.2 ± 1.5 mm Hg in study eyes without ectopia lentis (P=.016); the mean CRF was 8.2 ± 1.8 mm Hg and 11.3 ± 1.9 mm Hg, respectively (P<.001). The mean Goldman-correlated IOP was 11.7 ± 2.7 mm Hg in study eyes with ectopia lentis and 16.2 ± 4.3 in study eyes without ectopia lentis (P=.003); the mean corneal-compensated IOP was 13.5 ± 4.1 mm Hg and 15.6 ± 3.8 mm Hg, respectively (P=.07). The CH, CRF, and Goldman-correlated IOP were significantly lower in the Marfan syndrome eyes with ectopia lentis than in the Marfan syndrome eyes without ectopia lentis. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  19. Apparatus to measure the vapor pressure of slowly decomposing compounds from 1 Pa to 105 Pa (United States)

    Berg, Robert F.


    This article describes an apparatus and method for measuring vapor pressures in the range from 1 Pa to 105 Pa. Its three distinctive elements are : (1) the static pressure measurements were made with only a small temperature difference between the vapor and the condensed phase, (2) the sample was degassed in situ, and (3) the temperature range extended up to 200 °C. The apparatus was designed to measure metal-organic precursors, which often are toxic, pyrophoric, or unstable. Vapor pressures are presented for naphthalene, ferrocene, diethyl phthalate, and TEMAH (tetrakisethylmethylaminohafnium). Also presented are data for the temperature-dependent decomposition rate of TEMAH. PMID:27274567

  20. Pressure ulcer healing: what is it? What influences it? How is it measured? (United States)

    Xakellis, G C; Frantz, R A


    Defining healing requires a set of measurements that quantify the physical factors that change during healing. Such a list of measures gives a de facto definition of what constitutes pressure ulcer healing and what influences it. This paper attempts to answer a more specific question: Which measurements are strong candidates for inclusion in a tool for monitoring pressure ulcer healing? Three sets of clinical measurements are analyzed--the assessment proposed by the Agency for Health Care Policy and Research Guideline Development Panel for the Treatment of Pressure Ulcers; the recommendations of the Wound Healing Society; and the Pressure Sore Status Tool. The validity of the 11 clinical measures common across these assessment methods is examined using empiric evidence from studies of wound healing.

  1. Pico Gauges for Minimally Invasive Intracellular Hydrostatic Pressure Measurements1[C][W][OPEN (United States)

    Knoblauch, Jan; Mullendore, Daniel L.; Jensen, Kaare H.; Knoblauch, Michael


    Intracellular pressure has a multitude of functions in cells surrounded by a cell wall or similar matrix in all kingdoms of life. The functions include cell growth, nastic movements, and penetration of tissue by parasites. The precise measurement of intracellular pressure in the majority of cells, however, remains difficult or impossible due to their small size and/or sensitivity to manipulation. Here, we report on a method that allows precise measurements in basically any cell type over all ranges of pressure. It is based on the compression of nanoliter and picoliter volumes of oil entrapped in the tip of microcapillaries, which we call pico gauges. The production of pico gauges can be accomplished with standard laboratory equipment, and measurements are comparably easy to conduct. Example pressure measurements are performed on cells that are difficult or impossible to measure with other methods. PMID:25232014

  2. Nurse-measured or ambulatory blood pressure in routine hypertension care

    NARCIS (Netherlands)

    Veerman, D. P.; van Montfrans, G. A.


    Nurses are considered to evoke less white-coat hypertension, and might therefore be able to estimate average blood pressure as well as and more conveniently than ambulatory monitoring. The objective of the present study was to determine the correspondence between blood pressure measured by a doctor

  3. Probe pressure effects on human skin diffuse reflectance and fluorescence spectroscopy measurements (United States)

    Lim, Liang; Nichols, Brandon; Rajaram, Narasimhan; Tunnell, James W.


    Diffuse reflectance and fluorescence spectroscopy are popular research techniques for noninvasive disease diagnostics. Most systems include an optical fiber probe that transmits and collects optical spectra in contact with the suspected lesion. The purpose of this study is to investigate probe pressure effects on human skin spectroscopic measurements. We conduct an in-vivo experiment on human skin tissue to study the short-term (30 s) effects of probe pressure on diffuse reflectance and fluorescence measurements. Short-term light probe pressure (P0 physiological properties extracted from diffuse reflectance and fluorescence measurements, and less than 0 +/- 5% for diagnostically significant physiological properties. Absorption decreases with site-specific variations due to blood being compressed out of the sampled volume. Reduced scattering coefficient variation is site specific. Intrinsic fluorescence shows a large standard error, although no specific pressure-related trend is observed. Differences in tissue structure and morphology contribute to site-specific probe pressure effects. Therefore, the effects of pressure can be minimized when the pressure is small and applied for a short amount of time; however, long-term and large pressures induce significant distortions in measured spectra.

  4. Using Smartphone Pressure Sensors to Measure Vertical Velocities of Elevators, Stairways, and Drones (United States)

    Monteiro, Martín; Martí, Arturo C.


    We measure the vertical velocities of elevators, pedestrians climbing stairs, and drones (flying unmanned aerial vehicles), by means of smartphone pressure sensors. The barometric pressure obtained with the smartphone is related to the altitude of the device via the hydrostatic approximation. From the altitude values, vertical velocities are…

  5. Blood pressure measurement of all five fingers by strain gauge plethysmography

    DEFF Research Database (Denmark)

    Hirai, M; Nielsen, S L; Lassen, N A


    The aim of the present paper was to study the methodological problems involved in measuring systolic blood pressure in all five fingers by the strain gauge technique. In 24 normal subjects, blood pressure at the proximal phalanx of finger I and both at the proximal and the intermediate phalanx of...

  6. The feasibility and reliability of capillary blood pressure measurements in the fingernail fold

    NARCIS (Netherlands)

    de Graaff, Jurgen C.; Ubbink, Dirk Th; Lagarde, Sjoerd M.; Jacobs, Michael J. H. M.


    Capillary blood pressure is an essential parameter in the study of the (patho-)physiology of microvascular perfusion. Currently, capillary pressure measurements in humans are performed using a servo-nulling micropressure system containing an oil-water interface, which suffers some drawbacks. In

  7. Pressure/cross-sectional area probe in the assessment of urethral closure function. Reproducibility of measurement

    DEFF Research Database (Denmark)

    Lose, G; Schroeder, T


    -pressure zone and distally in the urethra. The in vitro study showed that cross sectional areas of 13-79 mm2 were determined with a SD of 1.4 mm2. In vivo measurements revealed that the urethral parameters: elastance, hysteresis, pressure and power of contraction during coughing and squeezing were fairly...

  8. A semi-empirical airfoil stall noise model based on surface pressure measurements

    DEFF Research Database (Denmark)

    Bertagnolio, Franck; Aagaard Madsen, Helge; Fischer, Andreas


    This work is concerned with the experimental study of airfoil stall and the modelling of stall noise. Using pressure taps and high-frequency surface pressure microphones flush-mounted on airfoils measured in wind tunnels and on an operating wind turbine blade, the characteristics of stall are ana...

  9. A computer-controlled system for generation of chemical vapours in in vitro dermal uptake studies. (United States)

    Rauma, Matias; Johanson, Gunnar


    Recent work in our laboratory suggests that dermal absorption and desorption of volatile chemicals may be assessed in vitro by thermogravimetric analysis (TGA), i.e. by passing chemical vapour over a piece of skin while recording the weight increase at constant temperature and humidity. This paper describes a high-precision automated vapour-generating system for use with the TGA equipment. The system consists of computer-controlled magnetic valves and mass flow meters that split and redirect a flow of pure, dry air through different stainless-steel gas wash bottles thermostated to 25.00+/-0.05 degrees C. Each wash bottle is filled with a neat volatile chemical and designed so that the air leaving reaches 100% saturation within seconds, as shown with cyclohexanone. The air leaving the wash bottles are combined and directed via stainless-steel liners to the skin piece in the TGA chamber. The liners are heated to 30 degrees C to prevent condensation of water or chemical. Special computer software was developed to allow automatic runs with different wash bottles (chemicals) and air flows over several days. A number of measurements were made to characterize the stability and reproducibility of the vapour-generating system. We have developed a computer-controlled vapour-generating system for use in measurements of dermal absorption of chemicals by thermal gravimetry. The system has high stability and reproducibility and produces little noise.

  10. Comparison of two species-specific oscillometric blood pressure monitors with direct blood pressure measurement in anesthetized cats. (United States)

    Cerejo, Sofia A; Teixeira-Neto, Francisco J; Garofalo, Natache A; Rodrigues, Jéssica C; Celeita-Rodríguez, Nathalia; Lagos-Carvajal, Angie P


    To compare the performance of 2 species-specific oscillometric blood pressure (OBP) monitors (petMAPclassic and petMAPgraphic ) with direct blood pressure measurement in anesthetized cats. Prospective, experimental study. Veterinary teaching hospital. Eight adult cats (3.2-5.5 kg). During isoflurane anesthesia, OBP cuffs were placed on the thoracic limb and on the base of the tail while invasive blood pressure (IBP) was recorded from a dorsal pedal artery. End-tidal isoflurane concentrations, with or without intravenous dopamine (n = 8), norepinephrine (n = 1), or phenylephrine (n = 1) were adjusted to change invasive mean arterial pressure (MAP) between 40 to 100 mm Hg. Data were analyzed by the Bland-Altman method and 4-quadrant plots. Mean biases and limits of agreement (LOA: ± 1.96 SD) (mm Hg) recorded between the petMAPclassic (thoracic limb) and IBP for systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and MAP were 4.2 ± 28.5, -6.1 ± 13.2, and -1.9 ± 14.6, respectively; mean biases and LOA (mm Hg) recorded with the tail cuff were 7.2 ± 31.3 (SAP), -6.1 ± 11.6 (DAP), and -1.1 ± 11.7 (MAP). Mean biases and LOA (mm Hg) between petMAPgraphic (thoracic limb) and IBP were 7.7 ± 27.0 (SAP), -4.3 ± 11.5 (DAP), 0.2 ± 13.0 (MAP); values recorded with the tail cuff were 10.9 ± 29.6 (SAP), -4.4 ± 11.7 (DAP), and -0.1 ± 12.1 (MAP). Concordance rates after excluding arterial pressure changes ≤ 5 mm Hg was ≥ 93% for both devices. Although both OBP monitors provide unacceptable SAP estimations, MAP values derived from both monitors and DAP measured by the petMAPgraphic result in acceptable agreement with the reference method according to the Association for the Advancement of Medical Instrumentation (mean bias ≤ 5 mm Hg with LOA ≤ ± 16 mm Hg). Both monitors provide acceptable trending ability for SAP, DAP, and MAP. © Veterinary Emergency and Critical Care Society 2017.

  11. Determination of dynamic pressure on infinite piezoelectric hollow cylinder from electric potential difference measurement

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H.M. [Department of Mechanics, School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310027 (China)], E-mail:; Ding, H.J. [Department of Civil Engineering, College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310027 (China)


    An analytical method is developed for evaluating the dynamic pressure acted at the surface of infinite piezoelectric hollow cylinder by measuring the electric potential difference between the internal and external surfaces. By virtue of the separation of variables method and the orthogonal expansion technique, the inverse boundary problem is transformed to a second kind Volterra integral equation about the unknown dynamic pressure. The interpolation method is employed to solve the integral equation and the dynamic pressure is determined. The present method is suitable for the hollow cylinder with arbitrary thickness subjected to arbitrary dynamic pressure. Numerical experiments are also presented.

  12. Second-harmonic-generation measurements on ZnSe under high pressure

    CERN Document Server

    Jin Ming Xing; Mukhtar, E; Ding Da Jun


    Second-harmonic-generation (SHG) measurements on ZnSe at high pressure, up to 7 GPa, have been reported. The zinc-blende-rock-salt transition pressure has been determined at room temperature from the SHG in ZnSe using a femtosecond laser. The pressure required to induce transformation from a zinc-blende to a rock-salt structure decreases from 11.5 to 1.07 GPa in a femtosecond laser field. SHG can be used to monitor structural changes under pressure of some materials with nonlinear optical properties.

  13. Pressure-stability of phospholipid bicelles: Measurement of residual dipolar couplings under extreme conditions

    Energy Technology Data Exchange (ETDEWEB)

    Brunner, E.; Arnold, M.R.; Kremer, W.; Kalbitzer, H.R. [University of Regensburg, Institute of Biophysics and Physical Biochemistry (Germany)


    High-pressure NMR of proteins in solutions currently gains increasing interest. 3D structure determination of proteins under high pressure is, however, so far impossible due to the lack of NOE information. Residual dipolar couplings induced by the addition of magnetically orienting media are known to be capable of replacing NOE information to a very high extent. In the present contribution we study the pressure-wstability of dimyristoylphosphatidylcholine (DMPC)/ dihexanoylphosphatidylcholine (DHPC) bicelles and demonstrate the feasibility of measuring residual dipolar couplings in proteins under high pressure.

  14. Effect of drilling fluid systems and temperature on oil mist and vapour levels generated from shale shaker. (United States)

    Steinsvåg, Kjersti; Galea, Karen S; Krüger, Kirsti; Peikli, Vegard; Sánchez-Jiménez, Araceli; Sætvedt, Esther; Searl, Alison; Cherrie, John W; van Tongeren, Martie


    Workers in the drilling section of the offshore petroleum industry are exposed to air pollutants generated by drilling fluids. Oil mist and oil vapour concentrations have been measured in the drilling fluid processing areas for decades; however, little work has been carried out to investigate exposure determinants such as drilling fluid viscosity and temperature. A study was undertaken to investigate the effect of two different oil-based drilling fluid systems and their temperature on oil mist, oil vapour, and total volatile organic compounds (TVOC) levels in a simulated shale shaker room at a purpose-built test centre. Oil mist and oil vapour concentrations were sampled simultaneously using a sampling arrangement consisting of a Millipore closed cassette loaded with glass fibre and cellulose acetate filters attached to a backup charcoal tube. TVOCs were measured by a PhoCheck photo-ionization detector direct reading instrument. Concentrations of oil mist, oil vapour, and TVOC in the atmosphere surrounding the shale shaker were assessed during three separate test periods. Two oil-based drilling fluids, denoted 'System 2.0' and 'System 3.5', containing base oils with a viscosity of 2.0 and 3.3-3.7 mm(2) s(-1) at 40°C, respectively, were used at temperatures ranging from 40 to 75°C. In general, the System 2.0 yielded low oil mist levels, but high oil vapour concentrations, while the opposite was found for the System 3.5. Statistical significant differences between the drilling fluid systems were found for oil mist (P = 0.025),vapour (P levels. Oil vapour levels at the test facility exceeded the Norwegian oil vapour occupational exposure limit (OEL) of 30 mg m(-3) when the drilling fluid temperature was ≥50°C. The practice of testing compliance of oil vapour exposure from drilling fluids systems containing base oils with viscosity of ≤2.0 mm(2) s(-1) at 40°C against the Norwegian oil vapour OEL is questioned since these base oils are very similar to white

  15. An optical method for measuring exhaust gas pressure from an internal combustion engine at high speed (United States)

    Leach, Felix C. P.; Davy, Martin H.; Siskin, Dmitrij; Pechstedt, Ralf; Richardson, David


    Measurement of exhaust gas pressure at high speed in an engine is important for engine efficiency, computational fluid dynamics analysis, and turbocharger matching. Currently used piezoresistive sensors are bulky, require cooling, and have limited lifetimes. A new sensor system uses an interferometric technique to measure pressure by measuring the size of an optical cavity, which varies with pressure due to movement of a diaphragm. This pressure measurement system has been used in gas turbine engines where the temperatures and pressures have no significant transients but has never been applied to an internal combustion engine before, an environment where both temperature and pressure can change rapidly. This sensor has been compared with a piezoresistive sensor representing the current state-of-the-art at three engine operating points corresponding to both light load and full load. The results show that the new sensor can match the measurements from the piezoresistive sensor except when there are fast temperature swings, so the latter part of the pressure during exhaust blowdown is only tracked with an offset. A modified sensor designed to compensate for these temperature effects is also tested. The new sensor has shown significant potential as a compact, durable sensor, which does not require external cooling.

  16. The effect of clothes on sphygmomanometric blood pressure measurement in hypertensive patients. (United States)

    Pinar, Rukiye; Ataalkin, Sıddıka; Watson, Roger


    To test whether there is any difference between blood pressure readings with patients wearing clothes under the manometer's cuff and not wearing clothes. The few studies published on this subject have shown that blood pressure measurements give similar results whether the patients' arm is covered by clothing or not. However, it has not been clarified whether this is also true in hypertensive patients. Blood pressure was measured on non-sleeved arm, sleeved arm and again on non-sleeved arm in 258 hypertensive patients using a mercury-filled column sphygmomanometer. Three nurses who were experienced and specially trained for the study performed blood pressure measurements. They were unaware of the purpose of the research. Measuring blood pressure with the manometer's cuff over participant's sleeved arm did not differ significantly from non-sleeved arm measurements. Sleeves have no effect on blood pressure results. Blood pressure readings taken over the sleeves will be much more practical and time saving in busy departments like emergency rooms, during disasters like earthquake where decisions have to make in minutes. Additionally, it will be time saving for general health screening surveys. Finally, it may have preferable because of hygiene concerns, patient privacy and religious beliefs. © 2010 Blackwell Publishing Ltd.

  17. Evaluation of skills and knowledge on orthostatic blood pressure measurements in elderly patients.

    NARCIS (Netherlands)

    Vloet, L.C.M.; Smits, R.; Frederiks, C.M.A.; Hoefnagels, W.H.L.; Jansen, R.W.M.M.


    OBJECTIVES: orthostatic hypotension is a common and potentially dangerous condition in elderly patients, often accompanied by dizziness and falls. To diagnose orthostatic hypotension, many physicians rely on blood pressure measurements performed by nurses. DESIGN: observational and descriptive

  18. In-Situ Rolling Element Bearing Temperature and/or Pressure Measurement

    National Research Council Canada - National Science Library

    Nickel, David


    ... attitude-control wheels. Thin-film deposition and patterning processes have been formulated for the production of thin-film resistive sensors for in-situ measurement of pressure and temperature transients in lubricated contacts...

  19. Poor Reliability of Wrist Blood Pressure Self-Measurement at Home: A Population-Based Study. (United States)

    Casiglia, Edoardo; Tikhonoff, Valérie; Albertini, Federica; Palatini, Paolo


    The reliability of blood pressure measurement with wrist devices, which has not previously been assessed under real-life circumstances in general population, is dependent on correct positioning of the wrist device at heart level. We determined whether an error was present when blood pressure was self-measured at the wrist in 721 unselected subjects from the general population. After training, blood pressure was measured in the office and self-measured at home with an upper-arm device (the UA-767 Plus) and a wrist device (the UB-542, not provided with a position sensor). The upper-arm-wrist blood pressure difference detected in the office was used as the reference measurement. The discrepancy between office and home differences was the home measurement error. In the office, systolic blood pressure was 2.5% lower at wrist than at arm (P=0.002), whereas at home, systolic and diastolic blood pressures were higher at wrist than at arm (+5.6% and +5.4%, respectively; Phome measurement error of at least ±5 mm Hg and 455 of at least ±10 mm Hg (bad measurers). In multivariable linear regression, a lower cognitive pattern independently determined both the systolic and the diastolic home measurement error and a longer forearm the systolic error only. This was confirmed by logistic regression having bad measurers as dependent variable. The use of wrist devices for home self-measurement, therefore, leads to frequent detection of falsely elevated blood pressure values likely because of a poor memory and rendition of the instructions, leading to the wrong position of the wrist. © 2016 American Heart Association, Inc.

  20. Leakage of volatile anaesthetics from agent-specific keyed vapourizer filling devices

    Energy Technology Data Exchange (ETDEWEB)

    Davies, J.M.; Strunin, L.; Craig, D.B.


    Agent-specific keyed vapourizer filling devices were designed to ensure that an anaesthetic vapourizer is filled with the correct agent. Since there appear to be no reports of possible loss of volatile agent or operating room pollution resulting from either the design or patterns of use of these devices, measurements were made with three anaesthetic agents and two methods of use. First, two bottles each of methoxyflurane, enflurane and halothane were fitted with a suitable filling device and the weight of agent lost from each bottle over six weeks was measured. Bottle number 1 of each agent remained without agitation between weighings; bottle number 2 was tipped to mimic filling of a vapourizer. Weight loss over the six week period was 2.76 and 3.15 per cent of the halothane, 2.22 and 2.43 per cent of the enflurane, and 0.58 and 0.96 per cent of the methoxyflurane, for bottles number 1 and number 2, respectively. Second, pollution was measured with an infra-red analyser for halothane, using bottles number 1 and number 2, as described above, and a third bottle on which the filling device was replaced by the screw-on cap after each filling of the vapourizer. Vapour loss was undetectable for bottle number 1, between 25 and 30 ppm for bottle number 2, and between 350 and 400 ppm for bottle number 3. Thus, although the design of the filling devices results in loss of the anaesthetic agent, this loss represents potential pollution only when the device is replaced by the screw-on cap between use. Therefore, when using filling devices, these should be left on the bottle of volatile agent between fillings to decrease operating room pollution.