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Sample records for intradiscal pressure measurements

  1. Intradiscal Pressure Changes during Manual Cervical Distraction: A Cadaveric Study

    Directory of Open Access Journals (Sweden)

    M. R. Gudavalli

    2013-01-01

    Full Text Available The objective of this study was to measure intradiscal pressure (IDP changes in the lower cervical spine during a manual cervical distraction (MCD procedure. Incisions were made anteriorly, and pressure transducers were inserted into each nucleus at lower cervical discs. Four skilled doctors of chiropractic (DCs performed MCD procedure on nine specimens in prone position with contacts at C5 or at C6 vertebrae with the headpiece in different positions. IDP changes, traction forces, and manually applied posterior-to-anterior forces were analyzed using descriptive statistics. IDP decreases were observed during MCD procedure at all lower cervical levels C4-C5, C5-C6, and C6-C7. The mean IDP decreases were as high as 168.7 KPa. Mean traction forces were as high as 119.2 N. Posterior-to-anterior forces applied during manual traction were as high as 82.6 N. Intraclinician reliability for IDP decrease was high for all four DCs. While two DCs had high intraclinician reliability for applied traction force, the other two DCs demonstrated only moderate reliability. IDP decreases were greatest during moving flexion and traction. They were progressevely less pronouced with neutral traction, fixed flexion and traction, and generalized traction.

  2. Biomechanical study on the effect of cervical spine fusion on adjacent-level intradiscal pressure and segmental motion.

    Science.gov (United States)

    Eck, Jason C; Humphreys, S Craig; Lim, Tae-Hong; Jeong, Soon Tack; Kim, Jesse G; Hodges, Scott D; An, Howard S

    2002-11-15

    A biomechanical study was performed using cadaveric cervical spine specimens. To determine the effect of cervical spine fusion on adjacent-level intradiscal pressure. Clinical studies have reported that patients with spinal fusion are at greater risk of pathology and early disc degeneration at adjacent levels. It is hypothesized that eliminating motion at one level leads to hypermobility and increased forces at adjacent levels, thus increasing the rate of disc degeneration. Six cadaveric cervical spine specimens were tested. Specimens were stabilized at T1 and loaded at C3 to 20 degrees of flexion and 15 degrees of extension. Intradiscal pressures and segmental motion at C4-C5 and C6-C7 were recorded first on intact specimens, and then after anterior cervical plating at C5-C6. Changes in intradiscal pressure and segmental motion were calculated and statistically analyzed using a paired Student t test. Intradiscal pressures were significantly increased during flexion at both adjacent levels. The pressure increased by 73.2% at C4-C5 (P = 0.002), and by 45.3% at C6-C7 (P = 0.006). Intradiscal pressures increased at both adjacent levels during extension, but not significantly. During flexion, segmental motion increased at both adjacent levels, with greater increases at C4-C5. During extension, segmental motion increased at both adjacent levels, with greater increases at C6-C7. Clinical studies have reported increased rates of disc degeneration at levels adjacent to fusion. It is believed that eliminating motion through fusion shifts the load to the adjacent levels, causing earlier disc degeneration. This study has shown that significant increases in intradiscal pressure and segmental motion occur at levels adjacent to fusion during normal range of motion. These results may partially explain the mechanism of early disc degeneration at levels adjacent to cervical spine fusion.

  3. Quantitative Discomanometry: Correlation of Intradiscal Pressure Values to Pain Reduction in Patients With Intervertebral Disc Herniation Treated With Percutaneous, Minimally Invasive, Image-Guided Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Filippiadis, Dimitrios K., E-mail: dfilippiadis@yahoo.gr; Mazioti, A., E-mail: argyromazioti@yahoo.gr; Papakonstantinou, O., E-mail: sogofianol@gmail.com; Brountzos, E., E-mail: ebrountz@med.uoa.gr [University General Hospital ' Attikon' , Second Radiology Department (Greece); Gouliamos, A., E-mail: agouliam@med.uoa.gr [University General Hospital ' Areteion' , First Radiology Department (Greece); Kelekis, N., E-mail: kelnik@med.uoa.gr; Kelekis, A., E-mail: akelekis@med.uoa.gr [University General Hospital ' Attikon' , Second Radiology Department (Greece)

    2012-10-15

    Purpose: To illustrate quantitative discomanometry's (QD) diagnostic efficacy and predictive value in discogenic-pain evaluation in a prospective study correlating intradiscal pressure values with pain reduction after percutaneous image-guided technique (i.e., percutaneous decompression, PD). Materials and Methods: During the last 3 years, 36 patients [21 male and 15 female (mean age 36 {+-} 5.8 years)] with intervertebral disc hernia underwent QD before PD. Under absolute sterilization and fluoroscopy, a mixture of contrast medium and normal saline (3:1 ratio) was injected. A discmonitor performed a constant rate injection and recorded pressure and volume values, thus producing the relative pressure-volume curve. PD was then performed. Pain reduction and improved mobility were recorded at 3, 12, and 24 months after PD using clinical evaluation and a numeric visual scale (NVS; 0 to 10 units). Results: Mean pain values of 7.5 {+-} 1.9 (range 4 to 8) NVS units were recorded before PD; these decreased to 2.9 {+-} 2.44 at 3 months, 1.0 {+-} 1.9 at 12 months, and 1.0 {+-} 1.9 NVS units at 24 months after PD. Recorded correlations (pressure, volume, significant pain-reduction values) with bilateral statistical significance included a maximum injected volume of 2.4 ml (p = 0.045), P{sub o} < 14 psi [initial pressure required to inject 0.1 ml of the mixture inside the disc (p = 0.05)], P{sub max} {<=} 65 psi [greatest pressure value on the curve (p = 0.018)], and P{sub max} - P{sub o} {<=} 47 psi (p = 0.038). Patients meeting these pressure or volume cut-off points, either independently or as a total, had significant pain reduction (>4 NVS units) after PD. No complications were noted. Conclusions: QD is an efficient technique that may have predictive value for discogenic pain evaluation. It might serve as a useful tool for patient selection for intervertebral disc therapies.

  4. Intradiscal corticosteroid injections in spondylotic cervical radiculopathy

    Energy Technology Data Exchange (ETDEWEB)

    Fayad, Fouad; Rannou, Francois; Rahmani, Lamia; Lefevre-Colau, Marie-Martine; Nys, Alain; Poiraudeau, Serge; Ledoux, Michel; Revel, Michel [Hopital Cochin (AP-HP) Universite Paris 5, Service de Reeducation et de Readaptation de l' Appareil Locomoteur et des Pathologies du Rachis, Paris (France); Drape, Jean L.; Chevrot, Alain [Hopital Cochin (AP-HP), Department of Radiology B, Paris (France)

    2007-05-15

    The purpose of this study was to evaluate treatment outcomes with intradiscal injection of corticosteroids (IDIC) in cervical spondylotic radiculopathy. Twenty consecutive patients were treated with intradiscal injection of 25 mg of acetate of prednisolone under fluoroscopic control. All patients had previously received a nonsurgical treatment for at least 3 months without success. Outcomes were assessed 1, 3 and 6 months after IDIC. Radicular pain reduction as scored on a visual analogue scale (VAS 100-mm length) was statistically significant at 1 month (19.0{+-}28.0 mm; p=0.008), 3 months (25.2{+-}27.5 mm; p=0.002), and 6 months (24.6{+-}28.4 mm; p=0.001). In all, 40% of treated patients described at least 50% pain improvement 6 months after treatment. Four patients had complete relief of radicular pain. In conclusion, IDIC should be an alternative in the nonsurgical management of cervical spondylotic radiculopathy. (orig.)

  5. Measuring fluid pressure

    International Nuclear Information System (INIS)

    Lee, A.S.

    1978-01-01

    A method and apparatus are described for measuring the pressure of a fluid having characteristics that make it unsuitable for connection directly to a pressure gauge. The method is particularly suitable for the periodic measurement of the pressure of a supply of liquid Na to Na-lubricated bearings of pumps for pumping Na from a reservoir to the bearing via a filter, the reservoir being contained in a closed vessel containing an inert blanket gas, such as Ar, above the Na. (UK)

  6. Intradiscal corticosteroid injections in spondylotic cervical radiculopathy

    International Nuclear Information System (INIS)

    Fayad, Fouad; Rannou, Francois; Rahmani, Lamia; Lefevre-Colau, Marie-Martine; Nys, Alain; Poiraudeau, Serge; Ledoux, Michel; Revel, Michel; Drape, Jean L.; Chevrot, Alain

    2007-01-01

    The purpose of this study was to evaluate treatment outcomes with intradiscal injection of corticosteroids (IDIC) in cervical spondylotic radiculopathy. Twenty consecutive patients were treated with intradiscal injection of 25 mg of acetate of prednisolone under fluoroscopic control. All patients had previously received a nonsurgical treatment for at least 3 months without success. Outcomes were assessed 1, 3 and 6 months after IDIC. Radicular pain reduction as scored on a visual analogue scale (VAS 100-mm length) was statistically significant at 1 month (19.0±28.0 mm; p=0.008), 3 months (25.2±27.5 mm; p=0.002), and 6 months (24.6±28.4 mm; p=0.001). In all, 40% of treated patients described at least 50% pain improvement 6 months after treatment. Four patients had complete relief of radicular pain. In conclusion, IDIC should be an alternative in the nonsurgical management of cervical spondylotic radiculopathy. (orig.)

  7. Fluoroscopic-guided intradiscal oxygen-ozone injection therapy for thoracolumbar intervertebral disc herniations in dogs.

    Science.gov (United States)

    Han, Hyun-Jung; Kim, Joon-Young; Jang, Ha-Young; Lee, Bora; Yoon, Jung-Hee; Jang, Sang-Keun; Choi, Seok Hwa; Jeong, Soon-Wuk

    2007-01-01

    To investigate the effect of oxygen-ozone (O2-O3) injection on thoracolumbar intervertebral disc herniation (IVDH) in dogs. Ten herniated discs of five dogs were treated with percutaneous injection of an O2-O3 gas mixture with O3 concentration of 32 microg/microl intradiscally (1.5-2 microl) under fluoroscopy guidance. Five weeks after treatment, the mean size of herniated discs was measured by computed tomography and showed significant reduction of disc volumes in all animals (8.8%+/-3.82%). The degree of shrinkage was negatively linearly correlated with disc mineralization (correlation coefficient=-0.636) and statistically significant at pdiscs by disc shrinkage.

  8. Nursing care for patients receiving percutaneous lumbar discectomy and intradiscal electrothermal treatment for lumbar disc herniation

    International Nuclear Information System (INIS)

    Mou Ling

    2009-01-01

    Objective: To summarize the nursing experience in caring patients with lumbar intervertebral disc herniation who received percutaneous lumbar discectomy (PLD) together with intradiscal electrothermal treatment (IDET) under DSA guidance. Methods: The perioperative nursing care measures carried out in 126 patients with lumbar intervertebral disc herniation who underwent PLD and IDET were retrospectively analyzed. Results: Successful treatment of PLD and IDET was accomplished in 112 cases. Under comprehensive and scientific nursing care and observation, no serious complications occurred. Conclusion: Scientific and proper nursing care is a strong guarantee for a successful surgery and a better recovery in treating lumbar intervertebral disc herniation with PLD and IDET under DSA guidance. (authors)

  9. Conservative therapy for lumbar intervertebral disc hernia. Intradiscal compressive injection and MRI findings

    International Nuclear Information System (INIS)

    Yoshida, Tohru; Nanba, Hiromichi; Kasai, Tsutomu; Ohta, Susumu

    1996-01-01

    To herniating intervertebral discs, 3-20 ml physiological saline was pressurized and injected. To avoid excessive force, the injection pressure was set at less than 3 kg/cm 2 . Between January 1993 and December 1994, 380 cases were studied (286 men and 94 women with a mean age of 45.5 years). After the compressive injection there were 259 (68.2%) effective cases in which symptoms were relieved and 121 ineffective cases (31.8%). The proportion of effective cases was higher in women than in men and in older than in younger patients. After intradiscal pressurized injection, the effective cases were investigated with MRI and a tendency to relatively early shrinkage of herniated mass was noted. (author)

  10. Conservative therapy for lumbar intervertebral disc hernia. Intradiscal compressive injection and MRI findings

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Tohru; Nanba, Hiromichi; Kasai, Tsutomu; Ohta, Susumu [Yoshida Orthopaedic Hospital, Toyota, Aichi (Japan)

    1996-01-01

    To herniating intervertebral discs, 3-20 ml physiological saline was pressurized and injected. To avoid excessive force, the injection pressure was set at less than 3 kg/cm{sup 2}. Between January 1993 and December 1994, 380 cases were studied (286 men and 94 women with a mean age of 45.5 years). After the compressive injection there were 259 (68.2%) effective cases in which symptoms were relieved and 121 ineffective cases (31.8%). The proportion of effective cases was higher in women than in men and in older than in younger patients. After intradiscal pressurized injection, the effective cases were investigated with MRI and a tendency to relatively early shrinkage of herniated mass was noted. (author).

  11. Pressure measurements in harsh environments

    International Nuclear Information System (INIS)

    Cook, C.W.; Ames, E.S.

    1979-01-01

    A fluid coupled plate (FCP) gage was designed which allows pressure measurements to be made in harsh environments (including debris) using conventional pressure transducers. The pressure transducer is isolated by means of a rigid force plate which is supported by a bellows having one corrugation. This portion of the gage is machined from a single piece of material. The interior of the gage is filled with a phenol fluid which has a low compressibility

  12. [Percutaneous intradiscal oxygen-ozone injection for lumbar disc herniation: no need of perioperative antibiotic prophylaxis].

    Science.gov (United States)

    Wei, Chuan-jun; Li, Yan-hao; Chen, Yong; Wang, Jiang-yun; Zeng, Qing-le; Zhao, Jian-bo; Mei, Que-lin

    2007-03-01

    To evaluate the feasibility of no antibiotic administration to prevent infection during the perioperative period of percutaneous intradiscal ozone-injection for treatment of lumbar disc herniation. Seventy-two patients with lumbar disc herniation but normal body temperature as well as normal results of three routine tests (blood, urine, stool) and C-reactive protein (CRP) level were randomly divided into two groups. The patients in prophylaxis group were given cephalothin V(2.0 g) intravenous 30 min before the operation, and the control group did not use any antibiotics. All the patients were injected with 6-10 ml ozone (40 microg/ml) for medical use into the discs with 21G needles under fluoroscopic guidance, followed by 10 ml ozone into the paravertebral space. Three days later the general examinations and CRP measurement were repeated. No infection was found in these patients, nor were any significant differences noted in the results of the examinations between the two groups after controlling in patients with above-normal white blood cell count, neutrophil percentage and CRP level. Prophylaxis antibiotics is not necessary during the perioperative period of percutaneous intradiscal ozone injection for lumbar disc herniation.

  13. Safety of intradiscal injection and biocompatibility of polyester amide microspheres in a canine model predisposed to intervertebral disc degeneration

    NARCIS (Netherlands)

    Willems, Nicole; Mihov, George; Grinwis, Guy C M; van Dijk, Maarten; Schumann, Detlef; Bos, Clemens; Strijkers, Gustav J; Dhert, Wouter J A; Meij, Björn P; Creemers, Laura B.; Tryfonidou, Marianna A

    Repair of degenerated intervertebral discs (IVD) might be established via intradiscal delivery of biologic therapies. Polyester amide polymers (PEA) were evaluated for in vitro cytotoxicity and in vivo biocompatibility, and thereafter intradiscal application of PEA microspheres (PEAMs) in a canine

  14. Device for measuring bed pressure

    Energy Technology Data Exchange (ETDEWEB)

    Gulin, B.M.; Chubar, V.G.

    1979-03-05

    The invention refers to studies in wells and is designed for piezomeasurements for the processes of undergrond leaching out associated with the movement of fluids of variable density to the productive beds. The purpose of he invention is to increase the accuracy of measurements of bed pressure by reducing the influence of changes of fluid density in the well. The goal is achieved because the device is equipped with a piezometric pipe arranged in the well and filled with liquid whose density is less than the density of the solution, and the transformer of the level is installed in the pipe. The pipe can have a throttle. A drawing and description of the proposed device are presented.

  15. Pressures Detector Calibration and Measurement

    CERN Document Server

    AUTHOR|(CDS)2156315

    2016-01-01

    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.

  16. High Precision Pressure Measurement with a Funnel

    Science.gov (United States)

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

    2008-01-01

    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…

  17. Pore Pressure Measurements Inside Rubble Mound Breakwaters

    DEFF Research Database (Denmark)

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

    2004-01-01

    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...

  18. New Vision Sensor to Measure Gas Pressure

    Directory of Open Access Journals (Sweden)

    Murawski Krzysztof

    2015-06-01

    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.

  19. A microwave pressure sounder. [for remote measurement of atmospheric pressure

    Science.gov (United States)

    Peckham, G. E.; Flower, D. A.

    1981-01-01

    A technique for the remote measurement of atmospheric surface pressure will be described. Such measurements could be made from a satellite in polar orbit and would cover many areas for which conventional meteorological data are not available. An active microwave instrument is used to measure the strength of return echoes from the ocean surface at a number of frequencies near the 60 GHz oxygen absorption band. Factors which affect the accuracy with which surface pressure can be deduced from these measurements will be discussed and an instrument designed to test the method by making measurements from an aircraft will be described.

  20. PIV-based pressure measurement

    International Nuclear Information System (INIS)

    Van Oudheusden, B W

    2013-01-01

    The topic of this article is a review of the approach to extract pressure fields from flow velocity field data, typically obtained with particle image velocimetry (PIV), by combining the experimental data with the governing equations. Although the basic working principles on which this procedure relies have been known for quite some time, the recent expansion of PIV capabilities has greatly increased its practical potential, up to the extent that nowadays a time-resolved volumetric pressure determination has become feasible. This has led to a novel diagnostic methodology for determining the instantaneous flow field pressure in a non-intrusive way, which is rapidly finding acceptance in an increasing variety of application areas. The current review describes the operating principles, illustrating how the flow-governing equations, in particular the equation of momentum, are employed to compute the pressure from the material acceleration of the flow. Accuracy aspects are discussed in relation to the most dominating experimental influences, notably the accuracy of the velocity source data, the temporal and spatial resolution and the method invoked to estimate the material derivative. In view of its nature of an emerging technique, recently published dedicated validation studies will be given specific attention. Different application areas are addressed, including turbulent flows, aeroacoustics, unsteady wing aerodynamics and other aeronautical applications. (topical review)

  1. PIV-based pressure measurement

    NARCIS (Netherlands)

    van Oudheusden, B.W.

    2013-01-01

    The topic of this article is a review of the approach to extract pressure fields from flow velocity field data, typically obtained with particle image velocimetry (PIV), by combining the experimental data with the governing equations. Although the basic working principles on which this procedure

  2. Commentary on differential-pressure measurements at high reference pressures

    International Nuclear Information System (INIS)

    Hasbrouck, R.T.; Noyes, R.P.

    1981-01-01

    Some practical approaches to the difficult problems in calibrating and implementing differential-pressure measurements are discussed. The data presented were gathered several years ago in separate investigations. An attempt is made to compare the results of these investigations to the common mode concept as described by Peter K. Stein in his publication, The Measurement of Differential Quantities - Problems and Approaches. Although one of these investigations involed a 10,000- to 20,000-psi reference-pressure gas measured at an ambient temperature and the other a classic /sup Δ/P flow measurement of cryogenic temperature, the problems encountered were the same

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

    NARCIS (Netherlands)

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

    2008-01-01

    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)

  4. On output measurements via radiation pressure

    DEFF Research Database (Denmark)

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

    1990-01-01

    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...

  5. Various pressure measurement technologies in nuclear engineering

    Energy Technology Data Exchange (ETDEWEB)

    Aritomi, Masanori (Tokyo Inst. of Tech. (Japan). Research Lab. for Nuclear Reactors); Hosoma, Takashi; Kawa, Tsunemichi

    1993-02-01

    Pressure measurement is one of major measurements in various plants as well as temperature and flow rate ones. Recently, a new pressure and differential pressure transducers, which can be applied to high temperature and high pressure conditions and have very high accuracy, were needed and have been developed to enhance safety of nuclear plants and reliability of their components. In the present paper, their new pressure measurement technologies, which have been established through using them in fundamental studies, proof testing and plants, are discussed from view points of their application to other nuclear fields. Furthermore, the measuring principle of the new sensors applied for their measurement technologies and the problems of their utilization are presented. (author).

  6. Various pressure measurement technologies in nuclear engineering

    International Nuclear Information System (INIS)

    Aritomi, Masanori; Hosoma, Takashi; Kawa, Tsunemichi.

    1993-01-01

    Pressure measurement is one of major measurements in various plants as well as temperature and flow rate ones. Recently, a new pressure and differential pressure transducers, which can be applied to high temperature and high pressure conditions and have very high accuracy, were needed and have been developed to enhance safety of nuclear plants and reliability of their components. In the present paper, their new pressure measurement technologies, which have been established through using them in fundamental studies, proof testing and plants, are discussed from view points of their application to other nuclear fields. Furthermore, the measuring principle of the new sensors applied for their measurement technologies and the problems of their utilization are presented. (author)

  7. Critical cerebral perfusion pressure at high intracranial pressure measured by induced cerebrovascular and intracranial pressure reactivity.

    Science.gov (United States)

    Bragin, Denis E; Statom, Gloria L; Yonas, Howard; Dai, Xingping; Nemoto, Edwin M

    2014-12-01

    The lower limit of cerebral blood flow autoregulation is the critical cerebral perfusion pressure at which cerebral blood flow begins to fall. It is important that cerebral perfusion pressure be maintained above this level to ensure adequate cerebral blood flow, especially in patients with high intracranial pressure. However, the critical cerebral perfusion pressure of 50 mm Hg, obtained by decreasing mean arterial pressure, differs from the value of 30 mm Hg, obtained by increasing intracranial pressure, which we previously showed was due to microvascular shunt flow maintenance of a falsely high cerebral blood flow. The present study shows that the critical cerebral perfusion pressure, measured by increasing intracranial pressure to decrease cerebral perfusion pressure, is inaccurate but accurately determined by dopamine-induced dynamic intracranial pressure reactivity and cerebrovascular reactivity. Cerebral perfusion pressure was decreased either by increasing intracranial pressure or decreasing mean arterial pressure and the critical cerebral perfusion pressure by both methods compared. Cortical Doppler flux, intracranial pressure, and mean arterial pressure were monitored throughout the study. At each cerebral perfusion pressure, we measured microvascular RBC flow velocity, blood-brain barrier integrity (transcapillary dye extravasation), and tissue oxygenation (reduced nicotinamide adenine dinucleotide) in the cerebral cortex of rats using in vivo two-photon laser scanning microscopy. University laboratory. Male Sprague-Dawley rats. At each cerebral perfusion pressure, dopamine-induced arterial pressure transients (~10 mm Hg, ~45 s duration) were used to measure induced intracranial pressure reactivity (Δ intracranial pressure/Δ mean arterial pressure) and induced cerebrovascular reactivity (Δ cerebral blood flow/Δ mean arterial pressure). At a normal cerebral perfusion pressure of 70 mm Hg, 10 mm Hg mean arterial pressure pulses had no effect on

  8. [Chemonucleolysis and intradiscal electrothermal therapy: what is the current evidence?].

    Science.gov (United States)

    Felder-Puig, R; Gyimesi, M; Mittermayr, T; Geiger-Gritsch, S

    2009-10-01

    We evaluated the efficacy and safety of chemonucleolysis and intradiscal electrothermal therapy (IDET) on the basis of the data presented in recently published papers with respect to pain relief, function, and complication rates. Detailed searches for English and German articles published between 2003 and 2008 were performed in a number of electronic databases. Further publications were identified by manual search. For summarizing the evidence, we considered only systematic reviews and controlled studies. The internal validity of reviews and studies was judged by two authors independently. Data extraction was performed by one author, and the extracted data was checked for completeness and correctness by a second author. The evidence of the efficacy of chemonucleolysis using chymopapain or collagenase is summarized in two recent, high-quality systematic reviews. We found 5 controlled studies evaluating nucleolysis using an oxygen-ozone mixture (O (2)O (3)-nucleolysis). Some of those studies were of limited methodological quality, but all showed the efficacy of O (2)O (3)-nucleolysis in comparison to microdiscectomy or the use of alternative substances. There is hardly any data regarding O (2)O (3)-nucleolysis complications. Regarding IDET, the authors of the 6 identified systematic reviews come to different conclusions about the efficacy of the procedure. The results of the 3 included controlled IDET studies, of which 2 are of high methodological quality, are also conflicting. The complication rates range from 0 to 15 %. In summary, the evidence of efficacy is presently more compelling for chemonucleolysis than for IDET. This may also be because indications for chemonucleolysis are more firmly established. However, safety aspects should be better evaluated and presented in the literature. Georg Thieme Verlag KG Stuttgart-New York.

  9. Radiofrequency-Induced Intradiscal Nucleoplasty Chronic Low Back Pain Secondary To Lumbar Disc Herniation

    Directory of Open Access Journals (Sweden)

    DW Lee

    2013-07-01

    Full Text Available We set out to assess the efficacy of radiofrequency-induced intradiscal nucleoplasty in reducing pain in symptomatic patients with MRI-defined lumbar disc herniation and their satisfaction with the procedure. We compared the patients’ pain intensity and severity of disability scores before and after undergoing the procedure in a retrospective questionnaire. These patients reported statistically significant reduction of pain intensity and disability level after the procedure. We conclude that radio frequency induced intradiscal nucleoplasty is an acceptable alternative minimally invasive procedure in relieving the symptoms of patients with lumbar disc herniation.

  10. Is intervertebral disc pressure linked to herniation?: An in-vitro study using a porcine model.

    Science.gov (United States)

    Noguchi, Mamiko; Gooyers, Chad E; Karakolis, Thomas; Noguchi, Kimihiro; Callaghan, Jack P

    2016-06-14

    Approximately 40% of low back pain cases have been attributed to internal disc disruption. This disruption mechanism may be linked to intradiscal pressure changes, since mechanical loading directly affects the pressure and the stresses that the inner annulus fibrosus experiences. The objective of this study was to characterize cycle-varying changes in four dependent measures (intradiscal pressure, flexion-extension moments, specimen height loss, and specimen rotation angle) using a cyclic flexion-extension (CFE) loading protocol known to induce internal disc disruption. A novel bore-screw pressure sensor system was used to instrument 14 porcine functional spinal units. The CFE loading protocol consisted of 3600 cycles of flexion-extension range of motion (average 18.30 (SD 3.76) degrees) at 1Hz with 1500N of compressive load. On average, intradiscal pressure and specimen height decreased by 47% and 62%, respectively, and peak moments increased by 102%. From 900 to 2100 cycles, all variables exhibited significant changes between successive time points, except for the specimen posture at maximum pressure, which demonstrated a significant shift towards flexion limit after 2700 cycles. There were no further changes in pressure range after 2100 cycles, whereas peak moments and height loss were significantly different from prior time points throughout the CFE protocol. Twelve of the 14 specimens showed partial herniation; however, injury type was not significantly correlated to any of the dependent measures. Although change in pressure was not predictive of damage type, the increase in pressure range seen during this protocol supports the premise that repetitive combined loading (i.e., radial compression, tension and shear) imposes damage to the inner annulus fibrosus, and its failure mechanism may be linked to fatigue. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. High precision pressure measurement with a funnel

    International Nuclear Information System (INIS)

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

    2008-01-01

    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 placed, upside down, in a container filled with distilled water, placed on a scale. Our method provides a theoretical precision for the pressure measurement of the order of 0.01 Pa. Beyond this, the advantage of this method relies on the simplicity of the materials used and on the opportunity to discuss, at an undergraduate level, basic concepts regarding all those phenomena in which low or very low differential pressures are relevant

  12. Blade Tip Pressure Measurements Using Pressure Sensitive Paint

    Science.gov (United States)

    Wong, Oliver D.; Watkins, Anthony Neal; Goodman, Kyle Z.; Crafton, James; Forlines, Alan; Goss, Larry; Gregory, James W.; Juliano, Thomas J.

    2012-01-01

    This paper discusses the application of pressure sensitive paint using laser-based excitation for measurement of the upper surface pressure distribution on the tips of rotor blades in hover and simulated forward flight. The testing was conducted in the Rotor Test Cell and the 14- by 22-ft Subsonic Tunnel at the NASA Langley Research Center on the General Rotor Model System (GRMS) test stand. The Mach-scaled rotor contained three chordwise rows of dynamic pressure transducers for comparison with PSP measurements. The rotor had an 11 ft 1 in. diameter, 5.45 in. main chord and a swept, tapered tip. Three thrust conditions were examined in hover, C(sub T) = 0.004, 0.006 and 0.008. In forward flight, an additional thrust condition, C(sub T) = 0.010 was also examined. All four thrust conditions in forward flight were conducted at an advance ratio of 0.35.

  13. Thermogravimetric measurements of liquid vapor pressure

    International Nuclear Information System (INIS)

    Rong Yunhong; Gregson, Christopher M.; Parker, Alan

    2012-01-01

    Highlights: ► Rapid determination of vapor pressure by TGA. ► Demonstration of limitations of currently available approaches in literature. ► New model for vapor pressure assessment of small size samples in TGA. ► New model accounts for vapor diffusion and sample geometry and measures vapor pressure normally within 10%. - Abstract: A method was developed using thermo-gravimetric analysis (TGA) to determine the vapor pressure of volatile liquids. This is achieved by measuring the rate of evaporation (mass loss) of a pure liquid contained within a cylindrical pan. The influence of factors like sample geometry and vapor diffusion on evaporation rate are discussed. The measurement can be performed across a wide range of temperature yielding reasonable results up to 10 kPa. This approach may be useful as a rapid and automatable method for measuring the volatility of flavor and fragrance raw materials.

  14. Sciatica: treatment with intradiscal and intraforaminal injections of steroid and oxygen-ozone versus steroid only.

    Science.gov (United States)

    Gallucci, Massimo; Limbucci, Nicola; Zugaro, Luigi; Barile, Antonio; Stavroulis, Emmanouil; Ricci, Alessandro; Galzio, Renato; Masciocchi, Carlo

    2007-03-01

    To prospectively compare the clinical effectiveness of intraforaminal and intradiscal injections of a mixture of a steroid, a local anesthetic, and oxygen-ozone (O(2)-O(3)) (chemodiscolysis) versus intraforaminal and intradiscal injections of a steroid and an anesthetic in the management of radicular pain related to acute lumbar disk herniation. Medical Ethical Committee approval and informed consent were obtained. One hundred fifty-nine patients (86 men, 73 women; age range, 18-71 years) were included and were randomly assigned to two groups. Seventy-seven patients (group A) underwent intradiscal and intraforaminal injections of a steroid and an anesthetic, and 82 patients (group B) underwent the same treatment with the addition of an O(2)-O(3) mixture. Procedures were performed with computed tomographic guidance. An Oswestry Low Back Pain Disability Questionnaire was administered before treatment and at intervals, the last at 6-month follow-up. Patients and clinicians were blinded as to which treatment was performed. Results were compared with the chi(2) test. After 6 months, treatment was successful in 36 (47%) patients in group A and in 61 (74%) patients in group B. The difference was significant (P < .01). Intraforaminal and intradiscal injections of a steroid, an anesthetic, and O(2)-O(3) are more effective at 6 months than injections of only a steroid and an anesthetic in the same sites.

  15. Pressure measurements in magnetic-fusion devices

    Energy Technology Data Exchange (ETDEWEB)

    Dylla, H.F.

    1981-11-01

    Accurate pressure measurements are important in magnetic fusion devices for: (1) plasma diagnostic measurements of particle balance and ion temperature; (2) discharge cleaning optimization; (3) vacuum system performance; and (4) tritium accountability. This paper reviews the application, required accuracy, and suitable instrumentation for these measurements. Demonstrated uses of ionization-type and capacitance-diaphragm gauges for various pressure and gas-flow measurements in tokamaks are presented, with specific reference to the effects of magnetic fields on gauge performance and the problems associated with gauge calibration.

  16. Pressure measurements in magnetic-fusion devices

    International Nuclear Information System (INIS)

    Dylla, H.F.

    1981-11-01

    Accurate pressure measurements are important in magnetic fusion devices for: (1) plasma diagnostic measurements of particle balance and ion temperature; (2) discharge cleaning optimization; (3) vacuum system performance; and (4) tritium accountability. This paper reviews the application, required accuracy, and suitable instrumentation for these measurements. Demonstrated uses of ionization-type and capacitance-diaphragm gauges for various pressure and gas-flow measurements in tokamaks are presented, with specific reference to the effects of magnetic fields on gauge performance and the problems associated with gauge calibration

  17. Strain measurements during pressurized thermal shock experiment

    International Nuclear Information System (INIS)

    Tarso Vida Gomes, P. de; Julio Ricardo Barreto Cruz; Tanius Rodrigues Mansur; Denis Henrique Bianchi Scaldaferri; Miguel Mattar Neto

    2005-01-01

    For the life extension of nuclear power plants, the residual life of most of their components must be evaluated along all their operating time. Concerning the reactor pressure vessel, the pressurized thermal shock (PTS) is a very important event to be considered. For better understanding the effects of this kind of event, tests are made. The approach described here consisted of building a simplified in-scale physical model of the reactor pressure vessel, submitting it to the actual operating temperature and pressure conditions and provoking a thermal shock by means of cold water flow in its external surface. To conduct such test, the Nuclear Technology Development Center (CDTN) has been conducting several studies related to PTS and has also built a laboratory that has made possible the simulation of the PTS loading conditions. Several cracks were produced in the external surface of the reactor pressure vessel model. Strain gages were fixed by means of electrical discharge welding over the cracks regions in both external and internal surfaces. The temperature was monitored in 10 points across the vessel wall. The internal pressure was manually controlled and monitored using a pressure transducer. Two PTS experiments were conducted and this paper presents the strain measurement procedures applied to the reactor pressure vessel model, during the PTS, using strain gages experimental methodology. (authors)

  18. A gas thermometer for vapor pressure measurements

    Science.gov (United States)

    Rusin, A. D.

    2008-08-01

    The pressure of an inert gas over the range 400 1000 K was measured on a tensimetric unit with a quartz membrane pressure gauge of enhanced sensitivity. It was shown that a reactor with a membrane null gauge could be used as a gas thermometer. The experimental confidence pressure and temperature intervals were 0.07 torr and 0.1 K at a significance level of 0.05. A Pt-Pt/10% Rh thermocouple was calibrated; the results were approximated by a polynomial of degree five. The error in temperature calculations was 0.25 K.

  19. Measuring the osmotic pressure of active colloids

    Science.gov (United States)

    Wang, Michael; Soni, Vishal; Magkiriadou, Sofia; Ferrari, Melissa; Youssef, Mina; Driscoll, Michelle; Sacanna, Stefano; Chaikin, Paul; Irvine, William

    We study the behavior of a system of colloidal spinners, consisting of weakly magnetic colloids driven by a rotating magnetic field. First the particles are allowed to sediment to an equilibrium density profile in a gravitational field, from which we measure the equilibrium equation of state. By spinning the particles at various frequencies, we introduce activity into the system through the hydrodynamic interactions between particles. We observe that the activity expands the sedimentation profile to a new steady state, from which we measure the pressure as a function of the density and activity. We compare the effects of activity on the pressure and mean-squared displacement of spinners and tracer particles.

  20. Optical pressure/density measuring means

    Science.gov (United States)

    Veligdan, J.T.

    1995-05-09

    An apparatus and method are disclosed for rapidly and accurately determining the pressure of a fluid medium in either a static or dynamic state. The pressure is determined by making a measurement of the velocity of a light beam that is directed through the fluid medium along a pathway that enables an integrated pressure measurement to be made along the pathway, rather than making such a measurement only at a single point in the medium. A HeNe laser is configured to emit a beam of two frequencies separated by about 2 MHz. One of these beam frequencies is directed through the fluid medium and is reflected back through the medium to a non-linear diode detector. The other beam frequency is passed directly to a diode detector without traversing said medium. The diode detector is operated to determine the frequency shift or beat frequency between the two beam frequencies. Any variation in the frequency of said reflected beam that is caused by a change in its velocity as it is passed through the fluid medium causes a change in the beat frequency. This beat frequency change is then converted to an output signal value corresponding to the pressure of the medium. The measurement instrument apparatus is remotely positioned relative to the medium being measured, thus the apparatus is immune from electro-magnetic interference and can operate in conditions of high radiation, corrosion and extraordinarily high temperature. 4 figs.

  1. Pressure-dependent measurements in superconductors

    Science.gov (United States)

    Suresh, N.; Tallon, J. L.

    2008-07-01

    To evaluate the performance of a home-built miniature non-magnetic piston clamp cell we have carried out extensive low-temperature (1.5 to 10 K) measurements of the critical field, Hc, for the element Pb up to a pressure of P = 1.2 GPa. Surprisingly, such data has not previously been reported above 0.3 GPa. From this data the electronic entropy, specific heat, thermal expansion coefficient and compressibility is calculated as a function of temperature, pressure and magnetic field. The zero-field data is consistent with direct thermodynamic measurements and the P-dependence of Tc and specific heat coefficient, γ(T, P), allows the determination of the P-dependence of the pairing interaction. Using Pb as a manometer we investigated the pressure dependence of oxygen isotope effect on Tc for YBa2Cu4O8.

  2. High Temperature Dynamic Pressure Measurements Using Silicon Carbide Pressure Sensors

    Science.gov (United States)

    Okojie, Robert S.; Meredith, Roger D.; Chang, Clarence T.; Savrun, Ender

    2014-01-01

    Un-cooled, MEMS-based silicon carbide (SiC) static pressure sensors were used for the first time to measure pressure perturbations at temperatures as high as 600 C during laboratory characterization, and subsequently evaluated in a combustor rig operated under various engine conditions to extract the frequencies that are associated with thermoacoustic instabilities. One SiC sensor was placed directly in the flow stream of the combustor rig while a benchmark commercial water-cooled piezoceramic dynamic pressure transducer was co-located axially but kept some distance away from the hot flow stream. In the combustor rig test, the SiC sensor detected thermoacoustic instabilities across a range of engine operating conditions, amplitude magnitude as low as 0.5 psi at 585 C, in good agreement with the benchmark piezoceramic sensor. The SiC sensor experienced low signal to noise ratio at higher temperature, primarily due to the fact that it was a static sensor with low sensitivity.

  3. Comparison of wind pressure measurements on Silsoe ...

    African Journals Online (AJOL)

    Comparison of wind pressure measurements on Silsoe experimental building from full-scale observation, wind-tunnel experiments and various CFD techniques. ... for anisotropic turbulence and curvature related strain effects and the same have been compared with the full-scale and wind-tunnel data for the present study.

  4. Measuring elevated intracranial pressure through noninvasive methods

    DEFF Research Database (Denmark)

    Kristiansson, Helena; Nissborg, Emelie; Bartek, Jiri

    2013-01-01

    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...

  5. Nanoprobe measurements of materials at megabar pressures

    International Nuclear Information System (INIS)

    Wang, L.; Ding, Y.; Yang, W.; Liu, W.; Cai, Z.; Kung, J.; Shu, J.; Hemley, R.J.; Mao, W.L.; Mao, H.

    2010-01-01

    The use of nanoscale x-ray probes overcomes several key limitations in the study of materials up to multimegabar (> 200) pressures, namely, the spatial resolution of measurements of multiple samples, stress gradients, and crystal domains in micron to submicron size samples in diamond-anvil cells. Mixtures of Fe, Pt, and W were studied up to 282 GPa with 250-600 nm size synchrotron x-ray absorption and diffraction probes. The probes readily resolve signals from individual materials, between sample and gasket, and peak pressures, in contrast to the 5-(micro)m-sized x-ray beams that are now becoming routine. The use of nanoscale x-ray beams also enables single-crystal x-ray diffraction studies in nominally polycrystalline samples at ultrahigh pressures, as demonstrated in measurements of (Mg,Fe)SiO 3 postperovskite. These capabilities have potential for driving a push toward higher maximum pressures and further miniaturization of high-pressure devices, in the process advancing studies at extreme conditions.

  6. [Invasive blood pressure measurements. Factual safety].

    Science.gov (United States)

    Nielsen, L H

    1994-08-01

    Intra-arterial blood pressure measurement is often used in patients with unstable haemodynamics. The demand for accuracy in such measurements is high. Usually these demands are fulfilled, but situations can occur where the dynamic characteristics of the system are exceeded. In order to acknowledge this situation, one must be aware of these dynamic characteristics. The significance of the system's resonance frequency and damping is described. A method to control the usability of the system is described.

  7. Equipment for liquid metal pressure measurement

    International Nuclear Information System (INIS)

    Jung, J.

    1977-01-01

    Equipment is proposed for measuring liquid metal pressure in piping or a tank. An auxiliary piping is connected to the piping or tank at the measuring point. The auxiliary piping transports liquid metal to a container by means of an electromagnetic pump. The piping also houses an electromagnetic flow ratemeter connected to an electric comparator. The comparator and the electromagnetic pump are connected to the pump output generator. (Z.M.)

  8. Intradiscal injection of oxygen-ozone gas mixture for the treatment of cervical disc herniations.

    Science.gov (United States)

    Alexandre, A; Corò, L; Azuelos, A; Buric, J; Salgado, H; Murga, M; Marin, F; Giocoli, H

    2005-01-01

    For disc herniations the use of open surgical approaches is reduced since new percutaneous methods allowing shrinkage of the disc and improvement of the radicular function are gaining interest. Studies on the spontaneous disappearance of disc fragments have demonstrated autoimmune responses with a chronic inflammatory reaction. Also radicular pain has been shown to be mostly due to biochemical mechanisms. Researchers in different fields surprisingly noticed that a brief, calculated, oxidative stress by ozone administration may correct a persistent imbalance due to excessive, chronic oxidative injury. Oxygen-ozone gas injection in painful patients has a dramatic effect on clinical symptoms. On these bases the intradiscal injection of oxygen-ozone gas has been conceived. We report the treatment on a series of patients affected by cervical disc pathology, treated by intradiscal injection of oxygen-ozone gas mixture. The effects both on pain and on radicular dysfunction are impressive. The morphological effect of the treatment was also evaluated by pathological examination.

  9. Signal quality measures for unsupervised blood pressure measurement

    International Nuclear Information System (INIS)

    Abdul Sukor, J; Redmond, S J; Lovell, N H; Chan, G S H

    2012-01-01

    Accurate systolic and diastolic pressure estimation, using automated blood pressure measurement, is difficult to achieve when the transduced signals are contaminated with noise or interference, such as movement artifact. This study presents an algorithm for automated signal quality assessment in blood pressure measurement by determining the feasibility of accurately detecting systolic and diastolic pressures when corrupted with various levels of movement artifact. The performance of the proposed algorithm is compared to a manually annotated reference scoring (RS). Based on visual representations and audible playback of Korotkoff sounds, the creation of the RS involved two experts identifying sections of the recorded sounds and annotating sections of noise contamination. The experts determined the systolic and diastolic pressure in 100 recorded Korotkoff sound recordings, using a simultaneous electrocardiograph as a reference signal. The recorded Korotkoff sounds were acquired from 25 healthy subjects (16 men and 9 women) with a total of four measurements per subject. Two of these measurements contained purposely induced noise artifact caused by subject movement. Morphological changes in the cuff pressure signal and the width of the Korotkoff pulse were extracted features which were believed to be correlated with the noise presence in the recorded Korotkoff sounds. Verification of reliable Korotkoff pulses was also performed using extracted features from the oscillometric waveform as recorded from the inflatable cuff. The time between an identified noise section and a verified Korotkoff pulse was the key feature used to determine the validity of possible systolic and diastolic pressures in noise contaminated Korotkoff sounds. The performance of the algorithm was assessed based on the ability to: verify if a signal was contaminated with any noise; the accuracy, sensitivity and specificity of this noise classification, and the systolic and diastolic pressure

  10. Comparison of pleural pressure measuring instruments.

    Science.gov (United States)

    Lee, Hans J; Yarmus, Lonny; Kidd, David; Ortiz, Ricardo; Akulian, Jason; Gilbert, Christopher; Hughes, Andrew; Thompson, Richard E; Arias, Sixto; Feller-Kopman, David

    2014-10-01

    The objective of this study was to compare the accuracy of a handheld digital manometer (DM) and U-tube (UT) manometer with an electronic transducer (ET) manometer during thoracentesis. Thirty-three consecutive patients undergoing thoracentesis were enrolled in the study. Pleural pressure (Ppl) measurements were made using a handheld DM (Compass; Mirador Biomedical), a UT water manometer, and an ET (reference instrument). End-expiratory Ppl was recorded after catheter insertion, after each aspiration of 240 mL, and prior to catheter removal. Volume of fluid removed, symptoms during thoracentesis, pleural elastance, and pleural fluid chemistry were also evaluated. A total of 594 Ppl measurements were made in 30 patients during their thoracenteses. There was a strong linear correlation coefficient between elastance for the DM and ET (r = 0.9582, P < .001). Correlation was poor between the UT and ET (r = 0.0448, P = .84). Among the 15 patients who developed cough, recorded ET pressures ranged from -9 to +9 cm H2O at the time of symptom development, with a mean (SD) of -2.93 (4.89) cm H2O. ET and DM measurements among those patients with cough had a low correlation between these measurements (R2 = 0.104, P = .24). Nine patients developed chest discomfort and had ET pressures that ranged from -26 to +6 cm H2O, with a mean (SD) of -7.89 (9.97) cm H2O. The handheld DM provided a valid and easy-to-use method to measure Ppl during thoracentesis. Future studies are needed to investigate its usefulness in predicting clinically meaningful outcomes.

  11. Polynomial analysis of ambulatory blood pressure measurements

    NARCIS (Netherlands)

    Zwinderman, A. H.; Cleophas, T. A.; Cleophas, T. J.; van der Wall, E. E.

    2001-01-01

    In normotensive subjects blood pressures follow a circadian rhythm. A circadian rhythm in hypertensive patients is less well established, and may be clinically important, particularly with rigorous treatments of daytime blood pressures. Polynomial analysis of ambulatory blood pressure monitoring

  12. On-line pressure measurement using scanning systems

    International Nuclear Information System (INIS)

    Morss, A.G.; Watson, A.P.

    1978-08-01

    Data collection methods can be improved significantly by using pressure scanning systems in conjunction with transducers for the measurement of pressure distribution in fluid flow rigs. However, the response of pressure transducers to the slight random pressure fluctuations that occur in practice can cause some measurement problems, especially for accurate work. The nature of these pressure fluctuations is examined and suitable analysis techniques are recommended. Results obtained using these techniques are presented. It is concluded that by using the correct techniques pressure transducer systems can be used to measure pressure distributions accurately and are sufficiently sensitive to measure very small systematic effects with great precision. (author)

  13. [New device and technique to measure intra-abdominal pressure].

    Science.gov (United States)

    Castañón-González, Jorge Alberto; Satué-Rodríguez, Julián; Carrillo Rosales, Francisco; Polanco-González, Carlos; Miranda-Ruíz, Rogelio; Camacho-Juárez, Sergio

    2013-01-01

    sequential measurement of intra-abdominal pressure is of paramount importance for an early detection and appropriate therapeutic management of intra-abdominal hypertension and abdominal compartment syndrome. to validate a device and technique developed to measure intra-abdominal pressure (an innovation of the Foley urinary catheter named intra-abdominal pressure catheter). three different sets of measurements where done to test the intra-abdominal pressure catheter device: I. 50 measurements were done with the intra-abdominal pressure catheter device and compared against those measurements done using a manometer graded in cm H(2)O; II. Direct measurement of intra-abdominal pressure in five patients during elective laparoscopy vs the intraabdominal pressure catheter device; and III. Measurement of intra-abdominal pressure by the Kron method (Gold standard) vs intra-abdominal pressure catheter device in three patents with intra-abdominal hypertension/abdominal compartment syndrome. Measurements where compared with Pearson correlation test and Bland Altman statistics. I.Intra-abdominal pressure catheter vs graded manometer: r = 0.99, with a mean pressure difference of 0.27 ± 0.23 mmHg, CI (0.039 to 0.092 mmHg). II. Direct measurement of intra-abdominal pressure during laparoscopy vs intra-abdominal pressure catheter device: r = 0.93, with a mean pressure difference of 0.18 ± 0.84 mmHg, CI (-1.46 to 1.83 mmHg) and III. Measurement of intra-abdominal pressure by the Kron Method vs intra-abdominal pressure catheter device: r = 0.81, with a mean pressure difference of -0.41 ± 0.87, CI (-2.12 mmHg to 1.30 mmHg). the intra-abdominal pressure catheter device is a safe and reliable instrument for measuring intra-abdominal pressure.

  14. Development and optimization of a device for diferencial pressure measurement

    International Nuclear Information System (INIS)

    Santarine, G.A.

    1980-01-01

    The measurements of reduced values of diferencial pressure, are studied. Several situations are described where the diferencial pressure accurate measurement is necessary in routine works in the Thermohydraulic Laboratory, as well as, the major pressure measurement devices and their respective range are studied. The development of a device for diferencial pressure measurement followed by the design development of the calibration bench covering the foreseen range, start up tests realization, optimization, calibration, performance analysis and conclusions, is showed. (Author) [pt

  15. Comparative evaluation of oxygen-ozone therapy and combined use of oxygen-ozone therapy with percutaneous intradiscal radiofrequency thermocoagulation for the treatment of lumbar disc herniation.

    Science.gov (United States)

    Gautam, Sujeet; Rastogi, V; Jain, Ankur; Singh, A P

    2011-01-01

    To compare the efficacy of oxygen-ozone therapy and the combined use of oxygen-ozone therapy with percutaneous intradiscal radiofrequency thermocoagulation (PIRFT) for the treatment of contained lumbar disc herniation. Ninety-one adult patients with low back pain secondary to contained lumbar disc herniation were randomly assigned into two groups. Ozone group received intradiscal oxygen-ozone therapy (4 to 7 mL of oxygen ozone mixture); ozone-PIRFT group received a combination of oxygen-ozone therapy with PIRFT (radiofrequency lesioning at 80°C for 360 s). Primary outcome measures included a visual analog scale (VAS) for pain and the Oswestry disability index (ODI). Secondary outcome measures included pain relief, reduction of analgesic consumption, and patient's satisfaction. Clinical assessment of these outcome measures was performed at 2 weeks, 1 month, 3 months, 6 months, and 1 year after the procedure. VAS scores and ODI were significantly decreased by both ozone and ozone-PIRFT when compared with the baseline values at all points of follow-up; however, ozone-PIRFT produced a significant reduction in the VAS scores and ODI when compared to ozone at 2 weeks, 1 month, 3 months, 6 months, and 1 year follow-up. Ozone-PIRFT also resulted in a significant change in all secondary measures at all points of follow-up, as compared with the ozone group. Ozone-PIRFT is more efficacious than ozone alone in reducing pain scores, analgesic consumption, improving functional outcome, and satisfaction of patients with contained lumbar disc herniation. © 2010 World Institute of Pain.

  16. Organic Electroluminescent Sensor for Pressure Measurement

    Directory of Open Access Journals (Sweden)

    Tomohide Niimi

    2012-10-01

    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.

  17. Organic electroluminescent sensor for pressure measurement.

    Science.gov (United States)

    Matsuda, Yu; Ueno, Kaori; Yamaguchi, Hiroki; Egami, Yasuhiro; Niimi, Tomohide

    2012-10-16

    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.

  18. Blood Pressure Measurement: Clinic, Home, Ambulatory, and Beyond

    Science.gov (United States)

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

    2014-01-01

    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

  19. Turbulent pressure fluctuations measured during CHATS

    Science.gov (United States)

    Steven P. Oncley; William J. Massman; Edward G. Patton

    2008-01-01

    Fast-response pressure fluctuations were included in the Canopy Horizontal Array of Turbulence Study (CHATS) at several heights within and just above the canopy in a walnut orchard. Two independent systems were intercompared and then separated. We present an evaluation of turbulence statistics - including the pressure transport term in the turbulence kinetic energy...

  20. 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...

  1. [An integrated system of blood pressure measurement with bluetooth communication].

    Science.gov (United States)

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

    2012-07-01

    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.

  2. Auscultatory versus oscillometric measurement of blood pressure in octogenarians

    DEFF Research Database (Denmark)

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

    2012-01-01

    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....

  3. [Measurement of blood pressure variability and the clinical value].

    Science.gov (United States)

    Kékes, Ede; Kiss, István

    2014-10-19

    Authors have collected and analyzed literature data on blood pressure variability. They present the methods of blood pressure variability measurement, clinical value and relationships with target organ damages and risk of presence of cardiovascular events. They collect data about the prognostic value of blood pressure variability and the effects of different antihypertensive drugs on blood pressure variability. They underline that in addition to reduction of blood pressure to target value, it is essential to influence blood pressure fluctuation and decrease blood pressure variability, because blood pressure fluctuation presents a major threat for the hypertensive subjects. Data from national studies are also presented. They welcome that measurement of blood pressure variability has been included in international guidelines.

  4. 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

    2002-01-01

    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.

  5. Lumbar puncture opening pressure is not a reliable measure of intracranial pressure in children.

    Science.gov (United States)

    Cartwright, Cathy; Igbaseimokumo, Usiakimi

    2015-02-01

    There is very little data correlating lumbar puncture pressures to formal intracranial pressure monitoring despite the widespread use of both procedures. The hypothesis was that lumbar puncture is a single-point measurement and hence it may not be a reliable evaluation of intracranial pressure. The study was therefore carried out to compare lumbar puncture opening pressures with the Camino bolt intracranial pressure monitor in children. Twelve children with a mean age of 8.5 years who had both lumbar puncture and intracranial pressure monitoring were analyzed. The mean lumbar puncture opening pressure was 22.4 mm Hg versus a mean Camino bolt intracranial pressure of 7.8 mm Hg (P intracranial pressure in children. There were no complications from the intracranial pressure monitoring, and the procedure changed the treatment of all 12 children avoiding invasive operative procedures in most of the patients. © The Author(s) 2014.

  6. Automated measurement of pressure injury through image processing.

    Science.gov (United States)

    Li, Dan; Mathews, Carol

    2017-11-01

    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 YC b C r 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

  7. Unsteady pressures on a blunt trailing edge measured with an embedded pressure scanner

    Science.gov (United States)

    Naughton, Jonathan; Nikoueeyan, Pourya; Hind, Michael; Strike, John; Dahland, Matz; Keeter, Steven

    2017-11-01

    Development of direct-mount pressure scanners can decrease the pneumatic tubing length required to connect the measurement ports to the scanner manifold resulting in improved dynamic range for unsteady pressure measurements. In this work, the performance of a direct-mount pressure scanner for time-resolved pressure measurement is demonstrated in a well-established flow; the pressure fluctuations near the base of flat plate is considered. The additive manufactured model is instrumented with a pressure scanner and flush-mounted high-speed pressure transducers. The configuration of the ports on the model allows for side-by-side comparison of the pressures measured via embedded pneumatic tubing routed to a pressure scanner with that measured by high-speed transducers. Prior to testing, the dynamic response of each embedded pressure port is dynamically calibrated via an in-situ calibration technique. Pressure data is then acquired for fixed angle-of-attack and different dynamic pitching conditions. The dynamic range of the measurements acquired via direct-mount scanner will be compared to those acquired by the high speed transducers for both static and dynamic pitching configurations. The uncertainties associated with Weiner deconvolution are also quantified for the measurements.

  8. Miniature uniaxial pressure cells for magnetic measurements

    Czech Academy of Sciences Publication Activity Database

    Kamarád, Jiří; Mihalik, M.; Sechovský, V.; Arnold, Zdeněk

    2008-01-01

    Roč. 28, č. 4 (2008), s. 633-636 ISSN 0895-7959 R&D Projects: GA ČR GA202/06/0178 Institutional research plan: CEZ:AV0Z10100521 Keywords : uniaxial compression * anisotropy * CuBe pressure cell Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.852, year: 2008

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

    African Journals Online (AJOL)

    Treatment of High Blood Pressure (JNC-7),8 with the subjects sitting quietly and the right arm on a table at the level of the heart. An appropriately sized cuff, covering at least two-thirds of the upper arm with the lower border not less than 2.5 cm from the cubital fossa, was applied after restricting clothing had been removed.

  10. Clinical value of blood pressure measurement in the community pharmacy.

    Science.gov (United States)

    Sabater-Hernández, Daniel; Azpilicueta, Inés; Sánchez-Villegas, Pablo; Amariles, Pedro; Baena, María I; Faus, María J

    2010-10-01

    To investigate whether the measurement of blood pressure in the community pharmacy is a valuable method to diagnose hypertension, to assess the need and the effectiveness of anti-hypertensive treatments, or, in general, to make clinical decisions. Information has been extracted from articles published in English and in Spanish, from January 1989 to December 2009, in indexed magazines in MEDLINE and EMBASE. To perform the search, multiple and specified terms related to the community pharmacy setting, to blood pressure measurement and to the comparison and agreement between blood pressure measurement methods were used. Selected articles were those that: (1) compared and/or measured the agreement (concordance) between community pharmacy blood pressure measurements obtained in repeated occasions, or (2) compared and/or measured the agreement between the community pharmacy blood pressure measurement method and other measurement methods used in clinical practice for decision-making purposes: blood pressure measurement by a physician, by a nurse and home or ambulatory blood pressure monitoring. Articles were included and analyzed by two investigators independently, who essentially extracted the main results of the manuscripts, emphasizing the assessment of the blood pressure measurement methods used and the completed statistical analysis. Only three studies comparing the community pharmacy blood pressure measurement method with other methods and one comparing repeated measurements of community pharmacy blood pressure were found. Moreover, these works present significant biases and limitations, both in terms of method and statistical analysis, which make difficult to draw consistent conclusions. Further research of high quality is needed, which results can guide the clinical decision-making based on the community pharmacy blood pressure measurement method.

  11. A method enabling simultaneous pressure and temperature measurement using a single piezoresistive MEMS pressure sensor

    International Nuclear Information System (INIS)

    Frantlović, Miloš; Stanković, Srđan; Jokić, Ivana; Lazić, Žarko; Smiljanić, Milče; Obradov, Marko; Vukelić, Branko; Jakšić, Zoran

    2016-01-01

    In this paper we present a high-performance, simple and low-cost method for simultaneous measurement of pressure and temperature using a single piezoresistive MEMS pressure sensor. The proposed measurement method utilizes the parasitic temperature sensitivity of the sensing element for both pressure measurement correction and temperature measurement. A parametric mathematical model of the sensor was established and its parameters were calculated using the obtained characterization data. Based on the model, a real-time sensor correction for both pressure and temperature measurements was implemented in a target measurement system. The proposed method was verified experimentally on a group of typical industrial-grade piezoresistive sensors. The obtained results indicate that the method enables the pressure measurement performance to exceed that of typical digital industrial pressure transmitters, achieving at the same time the temperature measurement performance comparable to industrial-grade platinum resistance temperature sensors. The presented work is directly applicable in industrial instrumentation, where it can add temperature measurement capability to the existing pressure measurement instruments, requiring little or no additional hardware, and without adverse effects on pressure measurement performance. (paper)

  12. Design and Development of a Pressure Transducer for High Hydrostatic Pressure Measurements up to 200 MPa

    Science.gov (United States)

    Kumar, Anuj; Yadav, Sanjay; Agarwal, Ravinder

    2017-08-01

    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.

  13. Reproducibility of repeated measurements with the Kikuhime pressure sensor under pressure garments in burn scar treatment.

    Science.gov (United States)

    Van den Kerckhove, Eric; Fieuws, Steffen; Massagé, Patrick; Hierner, Robert; Boeckx, Willy; Deleuze, Jean-Paul; Laperre, Jan; Anthonissen, Mieke

    2007-08-01

    This study investigated the reproducibility of repeated measurements with the Kikuhime pressure sensor under two different types of pressure garments used in the treatment and prevention of scars after burns. Also efficiency of garments was assessed in clinical circumstances by assessing pressure loss and residual pressure after 1 month. Intra- and inter-observer reproducibility and repeated measurements with 1-month time lapse were examined on 55 sites in 26 subjects by means of intra-class correlation coefficients and standard error of measurements. Results showed good to excellent ICC and low SEMs in the two conditions. There was a significant difference in pressure after 1 month between elastic tricot and weft knit garments, although evolution of pressure loss after 1 month was similar. Concerning different locations, there was a significant difference in pressure loss after 1 month between gloves and sleeves with the largest pressure loss for sleeves. Considering these results we concluded that the Kikuhime pressure sensor provides valid and reliable information and can be used in comparative clinical trials to evaluate pressure garments used in burn scar treatment. Secondly, elastic tricot garments in our study tended to have higher clinical pressures but both types of garments had similar pressure loss over time.

  14. Flight Investigation of the Effects of Pressure-Belt Tubing Size on Measured Pressure Distributions

    Science.gov (United States)

    Rivers, Natale A.; vanDam, Cornielious P.; Brown, Phillip W.; Rivers, Robert A.

    2001-01-01

    The pressure-belt technique is commonly used to measure pressure distributions on lifting and nonlifting surfaces where flush, through-the-surface measurements are not possible. The belts, made from strips of small-bore, flexible plastic tubing, are surface-mounted by a simple, nondestructive method. Additionally, the belts require minimal installation time, thus making them much less costly to install than flush-mounted pressure ports. Although pressure belts have been used in flight research since the early 1950s, only recently have manufacturers begun to produce thinner, more flexible tubing, and thin, strong adhesive tapes that minimize the installation-induced errors on the measurement of surface pressures. The objective of this investigation was to determine the effects of pressure-belt tubing size on the measurement of pressure distributions. For that purpose, two pressure belts were mounted on the right wing of a single-engine, propeller-driven research airplane. The outboard pressure belt served as a baseline for the measurement and the comparison of effects. Each tube had an outer diameter (OD) of 0.0625 in. The inboard belt was used to evaluate three different tube sizes: 0.0625-, 0.1250-, and 0.1875-in. OD. A computational investigation of tube size on pressure distribution also was conducted using the two-dimensional Multielement Streamtube Euler Solver (MSES) code.

  15. Measurement of earthworm radial pressures during peristaltic motion

    Science.gov (United States)

    Ruiz, Siul; Or, Dani

    2017-04-01

    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.

  16. The optimal scheme of self blood pressure measurement as determined from ambulatory blood pressure recordings

    NARCIS (Netherlands)

    Verberk, Willem J.; Kroon, Abraham A.; Kessels, Alfons G. H.; Lenders, Jacques W. M.; Thien, Theo; van Montfrans, Gert A.; Smit, Andries J.; de Leeuw, Peter W.

    Objective To determine how many self-measurements of blood pressure (BP) should be taken at home in order to obtain a reliable estimate of a patient's BP. Design Participants performed self blood pressure measurement (SBPM) for 7 days (triplicate morning and evening readings). In all of them, office

  17. Linewidth pressure measurement: a new technique for high vacuum characterization.

    Science.gov (United States)

    Jones, Chad A; Dearden, David V

    2015-02-01

    Pressure measurement is often the limiting factor in the accuracy of quantitative ion-molecule experiments. We present a new method for pressure measurement based on analysis of pressure-limited Fourier transform ion cyclotron resonance (FTICR) linewidths for well-characterized collisions of Ar(+) with Ar. The kinetic energy dependence of Ar(+)/Ar collision cross sections is well-described using a single-parameter fitting procedure, which results in pressure measurements in good agreement with those from a cold cathode tube and from measurement of total ion signal following electron impact ionization. The new method avoids problems inherent in ionization-based methods, such as those arising from differences in ionization potential or perturbations to the pressure that occur during electron ionization of the gas to be measured, and should be applicable in the trapping cells of FTICR and Orbitrap mass spectrometers.

  18. Modern gas-based temperature and pressure measurements

    CERN Document Server

    Pavese, Franco

    2013-01-01

    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...

  19. Comparison of three types of tongue pressure measurement devices.

    Science.gov (United States)

    Yoshikawa, Mineka; Yoshida, Mitsuyoshi; Tsuga, Kazuhiro; Akagawa, Yasumasa; Groher, Michael E

    2011-09-01

    A new tongue pressure device consisting of a simple and safe disposable probe and manometer has been developed. This report describes a study that examined the validity of the new device, comparing it to a widely used tongue pressure manometer, the Iowa Oral Performance Instrument (IOPI), and to the stable adhered three air-filled bulbs manometry system. The first test compared maximum tongue pressure measured with the new device and the IOPI (13 male, 9 female, 25.0 years). The second test compared maximum tongue pressure and swallowing tongue pressure measured with the new device and the three-bulb device (13 male, 9 female, 31.0 years). Significant correlations of maximum tongue pressure were found between the new device and the IOPI in the first test (p pressure were found between the new device at the anterior and middle sensors (p pressure between the new device and the three-bulb device were found (p pressure device are closely equivalent to those of the IOPI and three-bulb devices, demonstrating that the new device is capable of accurately measuring the pressure generated by the whole tongue.

  20. Combined NMR moisture, temperature and pressure measurements during heating

    Directory of Open Access Journals (Sweden)

    Pel L.

    2013-09-01

    Full Text Available For model validation, quantitative measurements of the evolution of moisture, temperature, and pressure distributions in time are needed. For this purpose, we have developed an NMR setup to measure the moisture transport in heated building materials. The measured combined moisture content and temperature profiles give a unique insight in the moisture transport and dehydration kinetics inside concrete during fire. These measurements give the first quantitative proof for the build-up of a moisture peak due to the vapor pressure build-up. In this study we have also combined for the first time the measurement of the moisture and temperature profiles with the measurement of the pressure at one position, which show that the pressure build up is directly related to the moisture profiles.

  1. Comparison of ambulatory blood pressure monitoring and office blood pressure measurements in obese children and adolescents.

    Science.gov (United States)

    Renda, Rahime

    2018-04-01

    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 lood 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 lood 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.

  2. Acute prevertebral abscess secondary to intradiscal oxygen-ozone chemonucleolysis for treatment of a cervical disc herniation.

    Science.gov (United States)

    Yang, Chun-Sheng; Zhang, Lin-Jie; Sun, Zhi-Hua; Yang, Li; Shi, Fu-Dong

    2018-01-01

    Objective We herein present a case involving a prevertebral abscess complicated by a spinal epidural abscess (SEA) secondary to intradiscal oxygen-ozone chemonucleolysis for treatment of a cervical disc herniation. Methods A 67-year-old woman with a history of intradiscal oxygen-ozone chemonucleolysis developed numbness and weakness in her right upper and bilateral lower extremities followed by urinary retention. Her symptoms did not respond to intravenous antibiotics alone. Magnetic resonance imaging of the cervical region revealed an extensive SEA anterior to the spinal cord, spinal cord myelopathy due to anterior compression by the lesion, and a prevertebral abscess extending from C2 to T1. She underwent surgical drainage and irrigation. Results The patient was successfully treated with surgical drainage and systemic antibiotic therapy without kyphosis. Streptococcus intermedius was detected within the abscess. All clinical symptoms except for the sensory deficit in the left leg were relieved. Conclusions The safety of intradiscal oxygen-ozone therapy requires further assessment. High-dose intravenous antibiotics should be initiated empirically at the earliest possible stage of prevertebral and epidural abscesses. Surgical drainage may be a rational treatment choice for patients with a prevertebral abscess complicated by an SEA and spinal cord myelopathy.

  3. A Graphene-Based Flexible Pressure Sensor with Applications to Plantar Pressure Measurement and Gait Analysis.

    Science.gov (United States)

    Lou, Cunguang; Wang, Shuo; Liang, Tie; Pang, Chenyao; Huang, Lei; Run, Mingtao; Liu, Xiuling

    2017-09-11

    In the present study, we propose and develop a flexible pressure sensor based on the piezoresistive effect of multilayer graphene films on polyester textile. The pressure response results from the deformation of graphene conductive network structure and the changes in resistance. Here, we show that the graphene pressure sensor can achieve a sensitivity value of 0.012 kPa - 1 , the measurement range can be as high as 800 kPa, and the response time can reach to 50 ms. Subsequently, a stable in-shoe wireless plantar pressure measurement system is developed and dynamic pressure distribution is acquired in real-time. Overall, the graphene textile pressure sensor has the advantage of wide dynamic range, flexibility and comfort, which provides the high possibility for footwear evaluation, clinical gait analysis and pathological foot diagnosis.

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

    DEFF Research Database (Denmark)

    Juhl, Peter; Jacobsen, Finn

    2004-01-01

    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...

  5. TREATMENT OF HYPERTENSION USING TELEMEDICAL HOME BLOOD PRESSURE MEASUREMENTS

    DEFF Research Database (Denmark)

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

    2015-01-01

    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...... 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....../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...

  6. Pico gauges for minimally invasive intracellular hydrostatic pressure measurements

    DEFF Research Database (Denmark)

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

    2014-01-01

    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...

  7. Association between blood pressure, measures of body composition ...

    African Journals Online (AJOL)

    Risk factors for development of cardiovascular disease develop early in life and track into adulthood. This study investigated the relationship between blood pressure (BP) and measures of body composition in adolescents. The study participants were 307 adolescents. Blood pressure (BP) and anthropometric parameters: ...

  8. New Technique of Direct Intra-abdominal Pressure Measurement

    Directory of Open Access Journals (Sweden)

    Elena Risin

    2006-10-01

    Conclusion: Direct measurement of intra-abdominal pressure using 14-Fr PVC round drain is a newly described technique that is simple, fast and credible. Future investigation will be needed to confirm the reliability of this method during postoperative follow-up of intra-abdominal pressures in selected patients.

  9. Definition-consistent measurement of exchange market pressure

    NARCIS (Netherlands)

    Klaassen, F.; Jager, H.

    2011-01-01

    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

  10. Endotracheal tube cuff pressure: need for precise measurement

    Directory of Open Access Journals (Sweden)

    José Reinaldo Cerqueira Braz

    1999-11-01

    Full Text Available CONTEXT: High compliance endotracheal tubes cuffs are used to prevent gas leak and also pulmonary aspiration in mechanically ventilated patients. However, the use of the usual cuff inflation volumes may cause tracheal damage. OBJECTIVE: We tested the hypothesis that endotracheal tube cuff pressures are routinely high (above 40 cmH2O in the Post Anesthesia Care Unit (PACU or Intensive Care Units (ICU. DESIGN: Cross-sectional study. SETTING: Post anesthesia care unit and intensive care unit. PARTICIPANTS: We measured endotracheal tubes cuff pressure in 85 adult patients, as follows: G1 (n = 31 patients from the ICU; G2 (n = 32 patients from the PACU, after anesthesia with nitrous oxide; G3 (n = 22 patients from the PACU, after anesthesia without nitrous oxide. Intracuff pressure was measured using a manometer (Mallinckrodt, USA. Gas was removed as necessary to adjust cuff pressure to 30 cmH2O. MAIN MEASUREMENTS: Endotracheal tube cuff pressure. RESULTS: High cuff pressure (> 40 cmH2O was observed in 90.6% patients of G2, 54.8% of G1 and 45.4% of G3 (P < 0.001. The volume removed from the cuff in G2 was higher than G3 (P < 0.05. CONCLUSION: Endotracheal tubes cuff pressures in ICU and PACU are routinely high and significant higher when nitrous oxide is used. Endotracheal tubes cuff pressure should be routinely measured to minimize tracheal trauma.

  11. Measuring static seated pressure distributions and risk for skin pressure ulceration in ice sledge hockey players.

    Science.gov (United States)

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

    2016-01-01

    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.

  12. Automatic noninvasive measurement of systolic blood pressure using photoplethysmography

    Directory of Open Access Journals (Sweden)

    Glik Zehava

    2009-10-01

    Full Text Available Abstract Background Automatic measurement of arterial blood pressure is important, but the available commercial automatic blood pressure meters, mostly based on oscillometry, are of low accuracy. Methods In this study, we present a cuff-based technique for automatic measurement of systolic blood pressure, based on photoplethysmographic signals measured simultaneously in fingers of both hands. After inflating the pressure cuff to a level above systolic blood pressure in a relatively slow rate, it is slowly deflated. The cuff pressure for which the photoplethysmographic signal reappeared during the deflation of the pressure-cuff was taken as the systolic blood pressure. The algorithm for the detection of the photoplethysmographic signal involves: (1 determination of the time-segments in which the photoplethysmographic signal distal to the cuff is expected to appear, utilizing the photoplethysmographic signal in the free hand, and (2 discrimination between random fluctuations and photoplethysmographic pattern. The detected pulses in the time-segments were identified as photoplethysmographic pulses if they met two criteria, based on the pulse waveform and on the correlation between the signal in each segment and the signal in the two neighboring segments. Results Comparison of the photoplethysmographic-based automatic technique to sphygmomanometry, the reference standard, shows that the standard deviation of their differences was 3.7 mmHg. For subjects with systolic blood pressure above 130 mmHg the standard deviation was even lower, 2.9 mmHg. These values are much lower than the 8 mmHg value imposed by AAMI standard for automatic blood pressure meters. Conclusion The photoplethysmographic-based technique for automatic measurement of systolic blood pressure, and the algorithm which was presented in this study, seems to be accurate.

  13. Automatic noninvasive measurement of systolic blood pressure using photoplethysmography.

    Science.gov (United States)

    Nitzan, Meir; Patron, Amikam; Glik, Zehava; Weiss, Abraham T

    2009-10-26

    Automatic measurement of arterial blood pressure is important, but the available commercial automatic blood pressure meters, mostly based on oscillometry, are of low accuracy. In this study, we present a cuff-based technique for automatic measurement of systolic blood pressure, based on photoplethysmographic signals measured simultaneously in fingers of both hands. After inflating the pressure cuff to a level above systolic blood pressure in a relatively slow rate, it is slowly deflated. The cuff pressure for which the photoplethysmographic signal reappeared during the deflation of the pressure-cuff was taken as the systolic blood pressure. The algorithm for the detection of the photoplethysmographic signal involves: (1) determination of the time-segments in which the photoplethysmographic signal distal to the cuff is expected to appear, utilizing the photoplethysmographic signal in the free hand, and (2) discrimination between random fluctuations and photoplethysmographic pattern. The detected pulses in the time-segments were identified as photoplethysmographic pulses if they met two criteria, based on the pulse waveform and on the correlation between the signal in each segment and the signal in the two neighboring segments. Comparison of the photoplethysmographic-based automatic technique to sphygmomanometry, the reference standard, shows that the standard deviation of their differences was 3.7 mmHg. For subjects with systolic blood pressure above 130 mmHg the standard deviation was even lower, 2.9 mmHg. These values are much lower than the 8 mmHg value imposed by AAMI standard for automatic blood pressure meters. The photoplethysmographic-based technique for automatic measurement of systolic blood pressure, and the algorithm which was presented in this study, seems to be accurate.

  14. Home blood pressure measurement in elderly patients with cognitive impairment: comparison of agreement between relative-measured blood pressure and automated blood pressure measurement.

    Science.gov (United States)

    Plichart, Matthieu; Seux, Marie-Laure; Caillard, Laure; Chaussade, Edouard; Vidal, Jean-Sébastien; Boully, Clémence; Hanon, Olivier

    2013-08-01

    Home blood pressure measurement (HBPM) is recommended by guidelines for hypertension management. However, this method might be difficult to use in elderly individuals with cognitive disorders. Our aim was to assess the agreement and the feasibility of HBPM by a relative as compared with 24-h ambulatory blood pressure monitoring (ABPM) in elderly patients with dementia. Sixty outpatients with dementia aged 75 years and older with office hypertension (≥140/90 mmHg) were subjected successively to HBPM by a trained relative and 24-h ABPM. The order of the two methods was randomized. Current guidelines' thresholds for the diagnosis of hypertension were used. The mean (SD) age of the patients was 80.8 (6.1) years (55% women) and the mean (SD) mini-mental state examination score was 20.1 (6.9). The feasibility of relative-HBPM was very high, with a 97% success rate (defined by ≥12/18 measurements reported). The blood pressure measurements were highly correlated between the two methods (r=0.75 and 0.64 for systolic blood pressure and diastolic blood pressure, respectively; Pmethods for the diagnosis of sustained hypertension and white-coat hypertension was excellent (overall agreement, 92%; κ coefficient, 0.81; 95% CI, 0.61-0.93). Similar results were found for daytime-ABPM. In cognitively impaired elderly patients, HBPM by a relative using an automated device was a good alternative to 24-h ABPM.

  15. Clinical Evaluation and Magnetic Resonance Imaging Assessment of Intradiscal Methylene Blue Injection for the Treatment of Discogenic Low Back Pain.

    Science.gov (United States)

    Zhang, XiaoJun; Hao, Jie; Hu, Zhenming; Yang, HaiTao

    2016-01-01

    Low back pain is a common worldwide health problem and has a significant socioeconomic impact on public health. Internal disc disruption has been considered as the most common cause of low back pain. Various therapies, including interbody fusion, disc replacement, injection therapies, and thermal annular procedures have been utilized for the treatment of discogenic low back pain. Recently, a new method of intradiscal methylene blue injection has been introduced to treat discogenic low back pain, but the clinical outcomes are controversial. To investigate the clinical outcomes and magnetic resonance imaging changes of intradiscal methylene blue injection for the treatment of discogenic low back pain. Observational study. An interventional low back pain management practice in a university hospital. A total of 33 patients were selected to be treated with intradiscal methylene blue injection. The clinical outcomes were evaluated by numeric rating scale and Oswestry Disability Index at pretreatment, one month, 3, 6, and 12 months after treatment. The magnetic resonance imaging changes of involved intervertebral discs were assessed by apparent diffusion coefficient and T2 values at pretreatment, 3, 6, and 12 months after treatment. All of the patients got a follow-up period up to 12 months. The mean numeric rating scale scores at pretreatment, one month, 3, 6, and 12 months after treatment were 6.54, 2.98, 3.23, 3.66, and 4.72, respectively. There was a minimum of 2 points reduction at one month, 3, and 6 months after treatment, but less than 2 points reduction at 12 months. There was at least 50% improvement on the Oswestry Disability Index at one month, 3, and 6 months after treatment, but not at 12 months. The mean apparent diffusion coefficient and T2 value were significantly higher at 6 and12 months after treatment compared to pretreatment, but there was no significant difference between pretreatment and 3 months after treatment. This is an observational study with

  16. 21 CFR 890.1600 - Intermittent pressure measurement system.

    Science.gov (United States)

    2010-04-01

    ... evaluative device intended for medical purposes, such as to measure the actual pressure between the body surface and the supporting media. (b) Classification. Class I (general controls). The device is exempt...

  17. Measurement of the differential pressure of liquid metals

    Science.gov (United States)

    Metz, H.J.

    1975-09-01

    This patent relates to an improved means for measuring the differential pressure between any two points in a process liquid metal coolant loop, wherein the flow of liquid metal in a pipe is opposed by a permanent magnet liquid metal pump until there is almost zero flow shown by a magnetic type flowmeter. The pressure producing the liquid metal flow is inferred from the rate of rotation of the permanent magnet pump. In an alternate embodiment, a differential pressure transducer is coupled to a process pipeline by means of high-temperature bellows or diaphragm seals, and a permanent magnet liquid metal pump in the high-pressure transmission line to the pressure transducer can be utilized either for calibration of the transducer or for determining the process differential pressure as a function of the magnet pump speed. (auth)

  18. Measurement of the differential pressure of liquid metals

    International Nuclear Information System (INIS)

    Metz, H.J.

    1975-01-01

    This patent relates to an improved means for measuring the differential pressure between any two points in a process liquid metal coolant loop, wherein the flow of liquid metal in a pipe is opposed by a permanent magnet liquid metal pump until there is almost zero flow shown by a magnetic type flowmeter. The pressure producing the liquid metal flow is inferred from the rate of rotation of the permanent magnet pump. In an alternate embodiment, a differential pressure transducer is coupled to a process pipeline by means of high-temperature bellows or diaphragm seals, and a permanent magnet liquid metal pump in the high-pressure transmission line to the pressure transducer can be utilized either for calibration of the transducer or for determining the process differential pressure as a function of the magnet pump speed

  19. Indications for portal pressure measurement in chronic liver disease

    DEFF Research Database (Denmark)

    Hobolth, Lise; Bendtsen, Flemming; Møller, Søren

    2012-01-01

    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 the hepatic venous pressure gradient (HVPG) independently predicts survival and development of complications such as ascites, HCC and bleeding from esophageal varices. Moreover, measurements of HVPG can be used to guide pharmacotherapy for primary and secondary prophylaxis for variceal bleeding. Assessment...

  20. Pressure and Relative Humidity Measurement Devices for Mars 2020 Rover

    Science.gov (United States)

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

    2017-09-01

    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.

  1. Blood pressure measurements in the ankle are not equivalent to ...

    African Journals Online (AJOL)

    Background. Blood pressure (BP) is often measured on the ankle in the emergency department (ED), but this has never been shown to be an acceptable alternative to measurements performed on the arm. Objective. To establish whether the differences between arm and ankle non-invasive BP measurements were clinically ...

  2. Use of an Ethanol-Driven Pressure Cell to Measure Hydrostatic Pressure Response of Protein-Stabilized Gold Nanoclusters

    Science.gov (United States)

    2016-01-01

    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

  3. Hepatic venous pressure gradients measured by duplex ultrasound

    International Nuclear Information System (INIS)

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

    2002-01-01

    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 -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)

  4. Validating Center-of-Pressure Balance Measurements Using the MatScan® Pressure Mat.

    Science.gov (United States)

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

    2018-01-24

    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. 30 healthy, young adults (19 female, 11 male, 22.7 ± 3.4 y, 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 s). Mean of the 3 trials was used to calculate 4 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 eyes-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 COP measurements were smaller than those of the force-plate, and the differences between devices appeared to increase as the measurement magnitude increased. Percent change in COP variables was highly correlated between devices (r > .85, P  2.25) and similar in 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 a viable option for detecting large magnitude changes in postural control during short-duration testing.

  5. A human cadaver fascial compartment pressure measurement model.

    Science.gov (United States)

    Messina, Frank C; Cooper, Dylan; Huffman, Gretchen; Bartkus, Edward; Wilbur, Lee

    2013-10-01

    Fresh human cadavers provide an effective model for procedural training. Currently, there are no realistic models to teach fascial compartment pressure measurement. We created a human cadaver fascial compartment pressure measurement model and studied its feasibility with a pre-post design. Three faculty members, following instructions from a common procedure textbook, used a standard handheld intra-compartment pressure monitor (Stryker(®), Kalamazoo, MI) to measure baseline pressures ("unembalmed") in the anterior, lateral, deep posterior, and superficial posterior compartments of the lower legs of a fresh human cadaver. The right femoral artery was then identified by superficial dissection, cannulated distally towards the lower leg, and connected to a standard embalming machine. After a 5-min infusion, the same three faculty members re-measured pressures ("embalmed") of the same compartments on the cannulated right leg. Unembalmed and embalmed readings for each compartment, and baseline readings for each leg, were compared using a two-sided paired t-test. The mean baseline compartment pressures did not differ between the right and left legs. Using the embalming machine, compartment pressure readings increased significantly over baseline for three of four fascial compartments; all in mm Hg (±SD): anterior from 40 (±9) to 143 (±44) (p = 0.08); lateral from 22 (±2.5) to 160 (±4.3) (p measurable fascial compartment pressure measurement model in a fresh human cadaver using a standard embalming machine. Set-up is minimal and the model can be incorporated into teaching curricula. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Optimal Approaches for Measuring Tongue-Pressure Functional Reserve

    Directory of Open Access Journals (Sweden)

    Catriona M. Steele

    2013-01-01

    Full Text Available Tongue-palate pressure is a parameter of considerable interest in the field of dysphagia. Maximum isometric tongue-palate pressures (MIPs decline in healthy aging and in dysphagia. Functional reserve (FR is the difference between MIPs and swallowing pressures. Reduced FR is thought to constitute a risk for developing functional swallowing impairments. We compare different approaches for calculating FR and recommend an optimal approach. Tongue-palate pressure data were collected from 78 healthy adults (4060 during anterior and posterior MIPs, regular (RESS and effortful (ESS saliva swallows, and water swallows (4 repetitions per task. Six different measures of reserve were calculated using maximum anterior MIPs or ESS pressures at the top, and mean or maximum RESS or water swallow pressures at the bottom of the range. Correlations with age and MIPs were explored to confirm suitability for measuring FR. The impact of normalization to maximum MIP range was explored. We conclude that an optimal measure of FR involves the comparison of maximum MIP with mean saliva swallowing pressures. This parameter declines with age, but when normalized to an individual’s MIP range, the relationship is no longer evident. This suggests that FR does not necessarily decline in healthy aging.

  7. MEASUREMENT OF FRICTIONAL PRESSURE DIFFERENTIALS DURING A VENTILATION SURVEY

    International Nuclear Information System (INIS)

    B.S. Prosser, PE; I.M. Loomis, PE, PhD

    2003-01-01

    During the course of a ventilation survey, both airflow quantity and frictional pressure losses are measured and quantified. The measurement of airflow has been extensively studied as the vast majority of ventilation standards/regulations are tied to airflow quantity or velocity. However, during the conduct of a ventilation survey, measurement of airflow only represents half of the necessary parameters required to directly calculate the airway resistance. The measurement of frictional pressure loss is an often misunderstood and misapplied part of the ventilation survey. This paper compares the two basic methods of frictional pressure drop measurements; the barometer and the gauge and tube. Personal experiences with each method will be detailed along with the authors' opinions regarding the applicability and conditions favoring each method

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

    Directory of Open Access Journals (Sweden)

    A. R. Rodi

    2012-11-01

    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.

  9. A technique for measuring absolute toe pressures: evaluation of pressure-sensitive film techniques.

    Science.gov (United States)

    Tuckman, A S; Werner, F W; Fortino, M D; Spadaro, J A

    1992-05-01

    Although a number of pathologies of the forefoot in ballet dancers on pointe have been described, pressures and deforming forces have not been adequately measured. To evaluate the possible use of pressure-sensitive film (PSF) in measuring the pressures on the external soft tissues in such a confined space as the dancer's toe shoe, it was tested and calibrated with 20 cadaver toes. Each cadaver toe was internally stabilized and loaded longitudinally against PSF on a flat surface. The resultant films were analyzed with a video imaging system and the pressures and total forces were determined. Results showed that the linearity of the PSF to pressure had a regression value of 0.98. By using two sensitivity ranges of films, the total force measured by the PSF was found to be within 10% of the known applied force on each toe. The PSF, therefore, may very well be a useful and accurate method of measuring external soft tissue pressures on the forefoot.

  10. MRI measurements of intracranial pressure in the upright posture: The effect of the hydrostatic pressure gradient.

    Science.gov (United States)

    Alperin, Noam; Lee, Sang H; Bagci, Ahmet M

    2015-10-01

    To add the hydrostatic component of the cerebrospinal fluid (CSF) pressure to magnetic resonance imaging (MRI)-derived intracranial pressure (ICP) measurements in the upright posture for derivation of pressure value in a central cranial location often used in invasive ICP measurements. Additional analyses were performed using data previously collected from 10 healthy subjects scanned in supine and sitting positions with a 0.5T vertical gap MRI scanner (GE Medical). Pulsatile blood and CSF flows to and from the brain were quantified using cine phase-contrast. Intracranial compliance and pressure were calculated using a previously described method. The vertical distance between the location of the CSF flow measurement and a central cranial location was measured manually in the mid-sagittal T1 -weighted image obtained in the upright posture. The hydrostatic pressure gradient of a CSF column with similar height was then added to the MR-ICP value. After adjustment for the hydrostatic component, the mean ICP value was reduced by 7.6 mmHg. Mean ICP referenced to the central cranial level was -3.4 ± 1.7 mmHg compared to the unadjusted value of +4.3 ± 1.8 mmHg. In the upright posture, the hydrostatic pressure component needs to be added to the MRI-derived ICP values for compatibility with invasive ICP at a central cranial location. © 2015 Wiley Periodicals, Inc.

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    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...... and Methods: We observed 81 pregnant diabetics’ ability to correctly self-measure in the waiting room during a 4-week observational descriptive study. Specifically, we investigated the level of patient adherence to six recommendations with which patients are in- structed to comply in order to obtain...

  12. Measurement of rock properties at elevated pressures and temperatures

    International Nuclear Information System (INIS)

    Pincus, H.J.; Hoskins, E.R.

    1985-01-01

    The papers in this volume were presented at an ASTM symposium held on 20 June 1983 in conjunction with the 24th Annual Rock Mechanics Symposium at Texas A and M University, College Station, TX. The purpose of these papers is to present recent developments in the measurement of rock properties at elevated pressures and temperatures, and to examine and interpret the data produced by such measurement. The need for measuring rock properties at elevated pressures and temperatures has become increasingly important in recent years. Location and design of nuclear waste repositories, development of geothermal energy sites, and design and construction of deep excavations for civil, military, and mining engineering require significantly improved capabilities for measuring rock properties under conditions substantially different from those prevailing in most laboratory and in situ work. The development of high-pressure, high-temperature capabilities is also significant for the analysis of tectonic processes

  13. 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 ...

  14. Wavenumber-frequency Spectra of Pressure Fluctuations Measured via Fast Response Pressure Sensitive Paint

    Science.gov (United States)

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

    2016-01-01

    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.

  15. A Manganin Thin Film Ultra-High Pressure Sensor for Microscale Detonation Pressure Measurement

    Directory of Open Access Journals (Sweden)

    Guodong Zhang

    2018-03-01

    Full Text Available With the development of energetic materials (EMs and microelectromechanical systems (MEMS initiating explosive devices, the measurement of detonation pressure generated by EMs in the microscale has become a pressing need. This paper develops a manganin thin film ultra-high pressure sensor based on MEMS technology for measuring the output pressure from micro-detonator. A reliable coefficient is proposed for designing the sensor’s sensitive element better. The sensor employs sandwich structure: the substrate uses a 0.5 mm thick alumina ceramic, the manganin sensitive element with a size of 0.2 mm × 0.1 mm × 2 μm and copper electrodes of 2 μm thick are sputtered sequentially on the substrate, and a 25 μm thick insulating layer of polyimide is wrapped on the sensitive element. The static test shows that the piezoresistive coefficient of manganin thin film is 0.0125 GPa−1. The dynamic experiment indicates that the detonation pressure of micro-detonator is 12.66 GPa, and the response time of the sensor is 37 ns. In a word, the sensor developed in this study is suitable for measuring ultra-high pressure in microscale and has a shorter response time than that of foil-like manganin gauges. Simultaneously, this study could be beneficial to research on ultra-high-pressure sensors with smaller size.

  16. A Manganin Thin Film Ultra-High Pressure Sensor for Microscale Detonation Pressure Measurement.

    Science.gov (United States)

    Zhang, Guodong; Zhao, Yulong; Zhao, Yun; Wang, Xinchen; Wei, Xueyong; Ren, Wei; Li, Hui; Zhao, You

    2018-03-01

    With the development of energetic materials (EMs) and microelectromechanical systems (MEMS) initiating explosive devices, the measurement of detonation pressure generated by EMs in the microscale has become a pressing need. This paper develops a manganin thin film ultra-high pressure sensor based on MEMS technology for measuring the output pressure from micro-detonator. A reliable coefficient is proposed for designing the sensor's sensitive element better. The sensor employs sandwich structure: the substrate uses a 0.5 mm thick alumina ceramic, the manganin sensitive element with a size of 0.2 mm × 0.1 mm × 2 μm and copper electrodes of 2 μm thick are sputtered sequentially on the substrate, and a 25 μm thick insulating layer of polyimide is wrapped on the sensitive element. The static test shows that the piezoresistive coefficient of manganin thin film is 0.0125 GPa -1 . The dynamic experiment indicates that the detonation pressure of micro-detonator is 12.66 GPa, and the response time of the sensor is 37 ns. In a word, the sensor developed in this study is suitable for measuring ultra-high pressure in microscale and has a shorter response time than that of foil-like manganin gauges. Simultaneously, this study could be beneficial to research on ultra-high-pressure sensors with smaller size.

  17. Noninvasive blood pressure measurement scheme based on optical fiber sensor

    Science.gov (United States)

    Liu, Xianxuan; Yuan, Xueguang; Zhang, Yangan

    2016-10-01

    Optical fiber sensing has many advantages, such as volume small, light quality, low loss, strong in anti-jamming. Since the invention of the optical fiber sensing technology in 1977, optical fiber sensing technology has been applied in the military, national defense, aerospace, industrial, medical and other fields in recent years, and made a great contribution to parameter measurement in the environment under the limited condition .With the rapid development of computer, network system, the intelligent optical fiber sensing technology, the sensor technology, the combination of computer and communication technology , the detection, diagnosis and analysis can be automatically and efficiently completed. In this work, we proposed a noninvasive blood pressure detection and analysis scheme which uses optical fiber sensor. Optical fiber sensing system mainly includes the light source, optical fiber, optical detector, optical modulator, the signal processing module and so on. wavelength optical signals were led into the optical fiber sensor and the signals reflected by the human body surface were detected. By comparing actual testing data with the data got by traditional way to measure the blood pressure we can establish models for predicting the blood pressure and achieve noninvasive blood pressure measurement by using spectrum analysis technology. Blood pressure measurement method based on optical fiber sensing system is faster and more convenient than traditional way, and it can get accurate analysis results in a shorter period of time than before, so it can efficiently reduce the time cost and manpower cost.

  18. Extremely-high vacuum pressure measurement by laser ionization

    International Nuclear Information System (INIS)

    Kokubun, Kiyohide

    1991-01-01

    Laser ionization method has the very high sensitivity for detecting atoms and molecules. Hurst et al. successfully detected a single Cs atom by means of resonance ionization spectroscopy developed by them. Noting this high sensitivity, the authors have attempted to apply the laser ionization method to measure gas pressure, particularly in the range down to extremely high vacuum. At present, hot cathode ionization gauges are used for measuring gas pressure down to ultrahigh vacuum, however, those have a number of disadvantages. The pressure measurement using lasers does not have such disadvantages. The pressure measurement utilizing the laser ionization method is based on the principle that when laser beam is focused through a lens, the amount of atom or molecule ions generated in the focused space region is proportional to gas pressure. In this paper, the experimental results are presented on the nonresonant multiphoton ionization characteristics of various kinds of gases, the ion detection system with high sensitivity and an extremely high vacuum system prepared for the laser ionization experiment. (K.I.)

  19. A Computer Controlled Precision High Pressure Measuring System

    Science.gov (United States)

    Sadana, S.; Yadav, S.; Jha, N.; Gupta, V. K.; Agarwal, R.; Bandyopadhyay, A. K.; Saxena, T. K.

    2011-01-01

    A microcontroller (AT89C51) based electronics has been designed and developed for high precision calibrator based on Digiquartz pressure transducer (DQPT) for the measurement of high hydrostatic pressure up to 275 MPa. The input signal from DQPT is converted into a square wave form and multiplied through frequency multiplier circuit over 10 times to input frequency. This input frequency is multiplied by a factor of ten using phased lock loop. Octal buffer is used to store the calculated frequency, which in turn is fed to microcontroller AT89C51 interfaced with a liquid crystal display for the display of frequency as well as corresponding pressure in user friendly units. The electronics developed is interfaced with a computer using RS232 for automatic data acquisition, computation and storage. The data is acquired by programming in Visual Basic 6.0. This system is interfaced with the PC to make it a computer controlled system. The system is capable of measuring the frequency up to 4 MHz with a resolution of 0.01 Hz and the pressure up to 275 MPa with a resolution of 0.001 MPa within measurement uncertainty of 0.025%. The details on the hardware of the pressure measuring system, associated electronics, software and calibration are discussed in this paper.

  20. Dynamic pressure measurement of cartridge operated vole captive bolt devices.

    Science.gov (United States)

    Frank, M; Philipp, K P; Franke, E; Frank, N; Bockholdt, B; Grossjohann, R; Ekkernkamp, A

    2009-01-10

    Vole captive bolt devices are powder actuated spring guns that are used as a pest control mean. After having triggered the explosion of the blank cartridge by touching a metal ring around the muzzle, the vole is killed by the massive propulsion of the gas jet. Improper use and recklessness while handling these devices may cause severe injuries with the hand of the operator at particular risk. Currently, there are no experimental investigations on the ballistic background of these devices. An experimental test set-up was designed for measurement of the firing pressure and the dynamic force of the gas jet of a vole captive bolt device. Therefore, a vole captive bolt device was prepared with a pressure take-off channel and a piezoelectric transducer for measurement of the firing pressure. For measurement of the dynamic impact force of the gas jet an annular quartz force sensor was installed on a test bench. Each three simultaneous measurements of the cartridges' firing pressure and the dynamic force of the blast wave were taken at various distances between muzzle and load washer. The maximum gas pressure in the explosion chamber was up to 1100 bar. The shot development over time showed a typical gas pressure curve. Flow velocity of the gas jet was up to 2000 m/s. The maximum impact force of the gas jet at the target showed a strong inverse ratio to the muzzle's distance and was up to 11,500 N for the contact shot distance. Energy density of the gas jet for the close contact shot was far beyond the energy density required for skin penetration. The unique design features (short tube between cartridge mouth and muzzle and narrow diameter of the muzzle) of these gadgets are responsible for the high firing pressure, velocity and force of the gas jet. These findings explain the trauma mechanics of the extensive tissue damage observed in accidental shots of these devices.

  1. An electronic manometer for blood-pressure measurement.

    Science.gov (United States)

    Burke, M J

    1999-01-01

    This article reports the development of an electronic manometer for use in the measurement of blood pressure. It is intended to act as a replacement gauge for the mercury and aneroid manometers used in conventional sphygmomanometers. It measures pressure in the range 0-300 mm Hg (0-40 kPa) with a resolution of 1 mm Hg (0.13 kPa) and an accuracy of +/- 1 mm Hg (+/- 0.13 kPa) which is displayed on a liquid crystal display. It operates from a 9 V PP3 battery over a temperature range of 10-50 degrees C.

  2. 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.

    2011-01-01

    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

  3. Design optimization and fabrication of a novel structural piezoresistive pressure sensor for micro-pressure measurement

    Science.gov (United States)

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

    2018-01-01

    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.

  4. Experimental viscosity measurements of biodiesels at high pressure

    Directory of Open Access Journals (Sweden)

    Schaschke C.J.

    2016-01-01

    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.

  5. Acoustics and Surface Pressure Measurements from Tandem Cylinder Configurations

    Science.gov (United States)

    Hutcheson, Florence V.; Brooks, Thomas F.; Lockard, David P.; Choudhari, Meelan M.; Stead, Daniel J.

    2014-01-01

    Acoustic and unsteady surface pressure measurements from two cylinders in tandem configurations were acquired to study the effect of spacing, surface trip and freestream velocity on the radiated noise. The Reynolds number ranged from 1.15x10(exp 5) to 2.17x10(exp 5), and the cylinder spacing varied between 1.435 and 3.7 cylinder diameters. The acoustic and surface pressure spectral characteristics associated with the different flow regimes produced by the cylinders' wake interference were identified. The dependence of the Strouhal number, peak Sound Pressure Level and spanwise coherence on cylinder spacing and flow velocity was examined. Directivity measurements were performed to determine how well the dipole assumption for the radiation of vortex shedding noise holds for the largest and smallest cylinder spacing tested.

  6. Transient pressure measurements at part load operating condition of ...

    Indian Academy of Sciences (India)

    Rahul Goyal

    hydraulic energy or demand of market. The turbine expe- riences unstable flow conditions during .... gate the pressure loading inside the turbine at a similar load. No measurements have been reported in the .... speed factor (nED) and discharge factor (qED) are 0.18 and. 0.15, respectively. The operating point selected for ...

  7. Combination of phlebography and sanguinous measurement of venous blood pressure

    International Nuclear Information System (INIS)

    Weber, J.

    1988-01-01

    Phlebographic visualisation offers the highest spatial resolution of all imaging methods both in respect of veins of the leg and pelvis and of the abdomen. Phlebography offers optimal conditions for assessing morphological changes at the veins and in their direct neighbourhood. No quantitative information is available via phlebography if haemodynamics are disturbed; qualitative information is yielded merely to a restricted extent (by assessing flow velocity and collaterals). Direct sanguinous measurement of venous blood pressure is particularly suitable for the quantitative and qualitative assessment of disturbed haemodynamic conditions; in this respect it stands out among the function tests based on the employment of apparatures. If it is combined with phlebography, it is possible not only to optimise the diagnostic yield in the hands of one investigator, but also to reduce the invasiveness of both methods to one single puncture, since the puncture needle is at the same time also an instrument to measure the pressure. The article points out the possibilities and limitations of combining a) ascending phlebography of the leg and pelvis with peripheral venous pressure measurement (phlebodynamometry) and b) visualisation of the veins of the pelvis and vena cava inferior with central sanguinous venous pressure measurement (CP). Indicatious and technical execution are described. (orig.) [de

  8. Measuring the local pressure amplitude in microchannel acoustophoresis

    DEFF Research Database (Denmark)

    Barnkob, Rune; Augustsson, Per; Laurell, Thomas

    2010-01-01

    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/gla...

  9. 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.

  10. A study of dynamic foot pressure measurement in diabetic patients

    Directory of Open Access Journals (Sweden)

    Milka D Madhale

    2017-01-01

    Full Text Available Introduction: Diabetic foot ulcer is a major source of morbidity and a leading cause of hospitalization. It is estimated that approximately 20% of hospital admissions among patients with diabetes mellitus are due to diabetic foot ulcer. It can lead to infection, gangrene, amputation, and even death if appropriate care is not provided. Overall, the lower limb amputation in diabetic patients is 15 times higher than in non-diabetics. In the majority of cases, the cause for the foot ulcer is the altered architecture of the foot due to neuropathy resulting in abnormal pressure points on the soles. Purpose: The aim of this study is to develop low cost, lightweight foot pressure scanner and check its reliability and validity which can help to prevent foot ulceration. Design/Methodology/Approach: In the present study, a low cost, lightweight foot pressure scanner is developed, and dynamic plantar pressures in a group of 110 Indian patients with diabetes with or without neuropathy and foot ulcers are measured. Practical Implications: If these pressure points can be detected, ulcers can be prevented by providing offloading footwear. Originality/Value: Differences are found in dynamic foot pressures in different study groups, namely, diabetic patients, patients with diabetic peripheral neuropathy, patients with foot ulcers, and nondiabetics. The differences are significant (P < 0.01, which showed the validity of the tool. Reliability and consistency of the tool was checked by test–retest method. Paper Type: Original Research work. Conclusion: Based on the results of the present study, it is concluded that the scanner is successfully developed and it can measure foot pressures. It is a novel device to proactively monitor foot health in diabetics in an effort to prevent and reduce diabetic foot complications.

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

    DEFF Research Database (Denmark)

    Laugesen, Esben; Knudsen, Søren Tang; Hansen, Klavs Würgler

    2016-01-01

    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 m...

  12. A lidar system for measuring atmospheric pressure and temperature profiles

    Science.gov (United States)

    Schwemmer, Geary K.; Dombrowski, Mark; Korb, C. Laurence; Milrod, Jeffry; Walden, Harvey

    1987-01-01

    The design and operation of a differential absorption lidar system capable of remotely measuring the vertical structure of tropospheric pressure and temperature are described. The measurements are based on the absorption by atmospheric oxygen of the spectrally narrowband output of two pulsed alexandrite lasers. Detailed laser output spectral characteristics, which are critical to successful lidar measurements, are presented. Spectral linewidths of 0.026 and 0.018 per cm for the lasers were measured with over 99.99 percent of the energy contained in three longitudinal modes.

  13. Static Pressure Measurements of a Low Power Arcjet

    Science.gov (United States)

    1991-12-01

    AFIT/GA/ENY/91D-6 AD-A243 898 DTICS EL E CT E JAN 0 3 1992 j STATIC PRESSURE MEASUREMENTS OF A LOW POWER ARCJET THESIS Kevin P. Talley, Captain...SUBTITLE 5. FUNDING NUMBERS STATIC PRESSURE MEASUREMVENTS OF A LOW POWER ARCJET 6. AUTHOR(S) Kevin P. Talley, Captain, USAF 7. PERFORMING ORGANIZATION...deliver 30 kW were on the drawing board and power available on commercial communications satellites had become large enough that low power arcjet thrusters

  14. A comparison of methods for detonation pressure measurement

    Science.gov (United States)

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

    2018-03-01

    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.

  15. Low back pain and sciatica: treatment with intradiscal-intraforaminal O(2)-O (3) injection. Our experience.

    Science.gov (United States)

    Muto, M; Ambrosanio, G; Guarnieri, G; Capobianco, E; Piccolo, G; Annunziata, G; Rotondo, A

    2008-08-01

    This paper describes discolysis by intradiscal, periganglionic and periradicular oxygen-ozone (O(2)-O(3)) injection, a minimally invasive percutaneous technique for the treatment of lumbar disk herniation. From June 2000 to December 2006, we performed O(2)-O(3) chemonucleolysis procedures in 2,900 patients affected by lumbar disk herniation. Patients were selected on the basis of clinical, psychological, neurological and neuroradiological criteria. Exclusion criteria were extruded hernia and/or free disc fragments, hyperalgesic-paralysing sciatica and progressive neurological impairment of the affected limb. All percutaneous treatments were performed under computed tomography (CT) guidance. All patients were evaluated after 1 month, and those showing only partial success were scheduled for a second treatment session. Results were evaluated with the modified MacNab classification, the visual analogue scale and the Oswestry Disability Index at 6 and 12 months. Success rates were 75%-80% for soft disc herniation, 70% for multiple-disc herniations and 55% for failed back surgery syndrome. None of the patients suffered early or late neurological or infectious complications. According to our data, minimally invasive percutaneous treatment by intradiscal, periradicular or periganglionic O(2)-O(3) infiltration is a valuable and competitive technique that provides excellent results at low cost and without complications.

  16. Intraoperative Sac Pressure Measurement During Endovascular Abdominal Aortic Aneurysm Repair

    International Nuclear Information System (INIS)

    Ishibashi, Hiroyuki; Ishiguchi, Tsuneo; Ohta, Takashi; Sugimoto, Ikuo; Iwata, Hirohide; Yamada, Tetsuya; Tadakoshi, Masao; Hida, Noriyuki; Orimoto, Yuki; Kamei, Seiji

    2010-01-01

    PurposeIntraoperative sac pressure was measured during endovascular abdominal aortic aneurysm repair (EVAR) to evaluate the clinical significance of sac pressure measurement.MethodsA microcatheter was placed in an aneurysm sac from the contralateral femoral artery, and sac pressure was measured during EVAR procedures in 47 patients. Aortic blood pressure was measured as a control by a catheter from the left brachial artery.ResultsThe systolic sac pressure index (SPI) was 0.87 ± 0.10 after main-body deployment, 0.63 ± 0.12 after leg deployment (P < 0.01), and 0.56 ± 0.12 after completion of the procedure (P < 0.01). Pulse pressure was 55 ± 21 mmHg, 23 ± 15 mmHg (P < 0.01), and 16 ± 12 mmHg (P < 0.01), respectively. SPI showed no significant differences between the Zenith and Excluder stent grafts (0.56 ± 0.13 vs. 0.54 ± 0.10, NS). Type I endoleak was found in seven patients (15%), and the SPI decreased from 0.62 ± 0.10 to 0.55 ± 0.10 (P = 0.10) after fixing procedures. Type II endoleak was found in 12 patients (26%) by completion angiography. The SPI showed no difference between type II endoleak positive and negative (0.58 ± 0.12 vs. 0.55 ± 0.12, NS). There were no significant differences between the final SPI of abdominal aortic aneurysms in which the diameter decreased in the follow-up and that of abdominal aortic aneurysms in which the diameter did not change (0.53 ± 0.12 vs. 0.57 ± 0.12, NS).ConclusionsSac pressure measurement was useful for instant hemodynamic evaluation of the EVAR procedure, especially in type I endoleaks. However, on the basis of this small study, the SPI cannot be used to reliably predict sac growth or regression.

  17. Refinement of Telemetry for Measuring Blood Pressure in Conscious Rats

    Science.gov (United States)

    Braga, Valdir A; Prabhakar, Nanduri R

    2009-01-01

    Although considered the ‘gold standard’ for measuring blood pressure in laboratory animals, telemetry would benefit from refinement. In the present study, we tested the hypothesis that the small telemetric device used for blood pressure recording in mice would work for rats as well and would serve as an alternative for those studies where abdominal cavity space is quite limited (such as in young animals and pregnant females). Here we report that the use of a smaller and lighter telemetric device implanted in the abdominal aorta of rats led to acquisition of stable and high-quality blood pressure and heart rate data, similar to those obtained by using a larger telemetric device developed for rats. The use of smaller transmitters represents an alternative telemetry technique, especially for those cases in which space in the abdominal cavity is particularly limited such as during pregnancy. PMID:19476715

  18. Treatment of the lumbar disc herniation with intradiscal and intraforaminal injection of oxygen-ozone.

    Science.gov (United States)

    Zhang, Yafeng; Ma, Yong; Jiang, Jianwei; Ding, Tao; Wang, Jianwei

    2013-01-01

    Oxygen-ozone therapy is a minimally invasive treatment for lumbar disk herniation that exploits the biochemical properties of a gas mixture of oxygen and ozone. The purpose of our study was to prospectively evaluate the clinical effectiveness of oxygen-ozone therapy and compared the therapeutic outcome of injection of oxygen-ozone combined steroid with injection of ozone alone at different follow-up period. From Aug 2005 to Mar 2009, 172 consecutive adult patients (92 men, 80 women; age range: 23-59 years) with low back pain and radicular pain were included in this study and were randomly assigned to two groups. 90 patients (group A) underwent intradiscal and intraforaminal injection of oxygen-ozone and 82 patients (group B) received the same treatment with additional injection of 1ml of compound betamethasone. Visual analogue scale (VAS) and the Japanese Orthopedic Association's evaluation system for lower back pain syndrome (JOA score) were administered before treatment and at 3 weeks, 6 and 12-month follow-up period to evaluate the clinical results. Satisfactory clinical outcomes were obtained in both groups. The reduction of VAS score from baseline to the end of the study was 7.68 to 2.17 and 7.49 to 2.23 in group A and group B respectively, and there were remarkable improvements of mean JOA score and recovery rate in every follow-up time in both groups. Furthermore, in 3 weeks follow-up the JOA recovery rate of group B is higher than that of group A, which there was significant different, but there were no significant differences between two groups in 6 and 12 months. In our study, oxygen-ozone nucleolysis provides excellent pain relief in most herniated disc patients who failed to respond to conservative therapy. And there was no significant statistical difference between treatment of injection of oxygen-ozone combined with steroid and ozone only in the 6 and 12 months follow-up. Therefore, O2-O3 seems to play a role in pain relief, and we suggest the

  19. Percutaneous treatment of herniated lumbar disc by intradiscal oxygen-ozone injection.

    Science.gov (United States)

    Muto, M; Avella, F

    1998-12-20

    We report our experience of treating lumbar herniated disc by intradiscal injection of an oxygen-ozone mixture. Ozone (03, MW = 48) is a triatomic molecule, having antiviral, disinfectant and antiseptic properties. Several mechanisms of action have been proposed to explain the efficacy of the treatment: 1) analgesic action; 2) anti-inflammatory action; 3) oxidant action on the proteoglycan in the nucleus pulposus. We treated 93 patients (50 women, 43 men) aged from 24 to 45 yrs (average age 38 yrs) from June 1996 to April 1998. All patients presented sciatica and/or low back pain, lasting two or more months; patients had in the mean time received both medical and physical therapy with mild or no benefit. Diagnostic tests in all patients included plain film x-ray, CT and/or MR at the level of the lumbar spine disclasing a herniated or protruded disc with nerve root or thecal sac compression. We divided patients to be treated in to two groups: the first one group included 35 patients already selected for surgery who presented herniated or protruded disc with radicular pain with associated neurological deficit (hypoesthesia and partial loss of reflex). Those patients had already had medical and physical therapy for two or more months and agreed to try the percutaneous treatment before surgery. CT or MR in this group demonstrated the presence of intraforaminal, extra or sub-ligamentary and sequestrated herniated disc. The second group included 58 patients with radicular pain but without neurological deficit; patients in this group had received medical and/or physical therapy for two or more months and CT showed the presence of a small subligamentary herniated or protruded disc. We considered the results according to the modified MacNab method. In the first group we had "failure" in all patients; in seven cases the symptoms improved for one month, but recurred later on. In the second group 45 patients had "success" showing complete clinical recovery within five to six

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

    Directory of Open Access Journals (Sweden)

    Subrata CHATTOPADHYAY

    2012-01-01

    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.

  1. A Prospective, Randomized, Multicenter, Open-label Clinical Trial Comparing Intradiscal Biacuplasty to Conventional Medical Management for Discogenic Lumbar Back Pain.

    Science.gov (United States)

    Desai, Mehul J; Kapural, Leonardo; Petersohn, Jeffrey D; Vallejo, Ricardo; Menzies, Robert; Creamer, Michael; Gofeld, Michael

    2016-07-01

    This study was a prospective, randomized, crossover, multicenter trial for the evaluation of comparative effectiveness of intradiscal biacuplasty (IDB) versus conventional medical management (CMM) in the treatment of lumbar discogenic pain. The objective was to demonstrate the superiority of IDB over CMM in the treatment of discogenic pain with respect to the primary outcome measure. Current therapeutic options for the treatment of chronic low back pain of discogenic origin are limited. CMM is often unsatisfactory with regard to the treatment of discogenic pain. IDB offers a minimally invasive treatment that has been demonstrated to be superior to placebo in the past. A total of 63 subjects with lumbar discogenic pain diagnosed via provocation discography were randomized to IDB + CMM (n = 29) or CMM-alone (n = 34). At 6 months, patients in the CMM-alone group were eligible for crossover if desired. The primary outcome measure was the change in visual analog scale (VAS) from baseline to 6 months. Secondary outcome measures included treatment "responders," defined as the proportion of subjects with a 2-point or 30% decrease in VAS scores. Other secondary measures included changes from baseline to 6 months in (1) short form (SF) 36-physical functioning, (2) Oswestry Disability Index, (3) Beck Depression Inventory, (4) Patient Global Impression of Change, (5) EQ-5D VAS, and (6) back pain-related medication usage. In the IDB cohort, the mean VAS score reduction exceeded that in the CMM cohort (-2.4 vs. -0.56; P = 0.02), and the proportion of treatment responders was substantially greater (50% vs. 18%). Differences in secondary measures favored IDB. No differences in opioid utilization were noted between groups. Superior performance of IDB with respect to all study outcomes suggests that it is a more effective treatment for discogenic pain than CMM-alone. 2.

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

    LENUS (Irish Health Repository)

    Hogan, Jennifer L

    2012-02-01

    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.

  3. Propagation of Radiosonde Pressure Sensor Errors to Ozonesonde Measurements

    Science.gov (United States)

    Stauffer, R. M.; Morris, G.A.; Thompson, A. M.; Joseph, E.; Coetzee, G. J. R.; Nalli, N. R.

    2014-01-01

    Several previous studies highlight pressure (or equivalently, pressure altitude) discrepancies between the radiosonde pressure sensor and that derived from a GPS flown with the radiosonde. The offsets vary during the ascent both in absolute and percent pressure differences. To investigate this problem further, a total of 731 radiosonde-ozonesonde launches from the Southern Hemisphere subtropics to Northern mid-latitudes are considered, with launches between 2005 - 2013 from both longer-term and campaign-based intensive stations. Five series of radiosondes from two manufacturers (International Met Systems: iMet, iMet-P, iMet-S, and Vaisala: RS80-15N and RS92-SGP) are analyzed to determine the magnitude of the pressure offset. Additionally, electrochemical concentration cell (ECC) ozonesondes from three manufacturers (Science Pump Corporation; SPC and ENSCI-Droplet Measurement Technologies; DMT) are analyzed to quantify the effects these offsets have on the calculation of ECC ozone (O3) mixing ratio profiles (O3MR) from the ozonesonde-measured partial pressure. Approximately half of all offsets are 0.6 hPa in the free troposphere, with nearly a third 1.0 hPa at 26 km, where the 1.0 hPa error represents 5 persent of the total atmospheric pressure. Pressure offsets have negligible effects on O3MR below 20 km (96 percent of launches lie within 5 percent O3MR error at 20 km). Ozone mixing ratio errors above 10 hPa (30 km), can approach greater than 10 percent ( 25 percent of launches that reach 30 km exceed this threshold). These errors cause disagreement between the integrated ozonesonde-only column O3 from the GPS and radiosonde pressure profile by an average of +6.5 DU. Comparisons of total column O3 between the GPS and radiosonde pressure profiles yield average differences of +1.1 DU when the O3 is integrated to burst with addition of the McPeters and Labow (2012) above-burst O3 column climatology. Total column differences are reduced to an average of -0.5 DU when

  4. Measurement of rabbit intraocular pressure with the Tono-Pen.

    Science.gov (United States)

    Mermoud, A; Baerveldt, G; Minckler, D S; Lee, M B; Rao, N A

    1995-01-01

    A Tono-Pen-1 (TP-1) and a Tono-Pen-2 (TP-2) were calibrated against direct manometry in the eyes of living rabbits to determine the accuracy of the Tono-Pen. Eighteen normal eyes of 10 rabbits were cannulated and connected to a pressure transducer with a chart recorder. Intraocular pressure (IOP) was increased from 5 to 40 mm Hg in 5-mm-Hg increments and from 40 to 80 mm Hg in 10-mm-Hg increments. After each incremental increase, IOP was measured first with a TP-1 and then with a TP-2. Plotting the mean Tono-Pen readings for each eye against the transducer pressure produced the following two regression line formulas: y = -0.613+0.790x (r2 = 0.97) for TP-1, and y = -1.45+0.824x (r2 = 0.97) for TP-2. Neither regression line was statistically different; p = 0.2 for the two slopes, and p = 0.24 for the y-axis intersection. The TP-1 and TP-2 can be used to rapidly and accurately measure the IOP in normal rabbit eyes. Tono-Pen readings do, however, significantly underestimate pressures in the range of 5-80 mm Hg. A table with 95% confidence intervals for corrected IOP readings obtained with the TP-1 or -2 is provided.

  5. Surface Pressure Measurements of Atmospheric Tides Using Smartphones

    Science.gov (United States)

    Price, Colin; Maor, Ron

    2017-04-01

    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.

  6. How important is the recommended slow cuff pressure deflation rate for blood pressure measurement?

    Science.gov (United States)

    Zheng, Dingchang; Amoore, John N; Mieke, Stephan; Murray, Alan

    2011-10-01

    Cuff pressure deflation rate influences blood pressure (BP) measurement. However, there is little quantitative clinical evidence on its effect. Oscillometric pulses recorded from 75 subjects at the recommended deflation rate of 2-3 mmHg per second were analyzed. Some pulses were removed to realize six faster rates (2-7 times faster than the original). Systolic, diastolic, and mean arterial blood pressures (SBP, DBP, MAP) were determined from the original and six reconstructed oscillometric waveforms. Manual measurement was based on the appearance of oscillometric pulse peaks, and automatic measurement on two model envelopes (linear and polynomial) fitted to the sequence of oscillometric pulse amplitudes. The effects of deflation rate on BP determination and within-subject BP variability were analyzed. For SBP and DBP determined from the manual measurement, different deflation rates resulted in significant changes (both p deflation rate effect (all p > 0.3). Faster deflation increased the within-subject BP variability (all p deflation rate, and for the automatic model-based techniques, the deflation rate had little effect.

  7. Interpretation of Strain Measurements on Nuclear Pressure Vessels

    DEFF Research Database (Denmark)

    Andersen, Svend Ib Smidt; Engbæk, Preben

    1980-01-01

    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...

  8. 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

    1980-01-01

    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......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...

  9. Single intradiscal injection of the interleukin-6 receptor antibody tocilizumab provides short-term relief of discogenic low back pain; prospective comparative cohort study.

    Science.gov (United States)

    Sainoh, Takeshi; Orita, Sumihisa; Miyagi, Masayuki; Inoue, Gen; Yamauchi, Kazuyo; Suzuki, Miyako; Sakuma, Yoshihiro; Kubota, Go; Oikawa, Yasuhiro; Inage, Kazuhide; Sato, Jun; Nakata, Yukio; Aoki, Yasuchika; Takahashi, Kazuhisa; Ohtori, Seiji

    2016-01-01

    Inflammatory cytokines, such as interleukin-6 and tumor necrosis factor-α, are gaining attention as important etiologic factors associated with discogenic low back pain. We conducted a prospective cohort study to evaluate the efficacy and safety of intradiscal injection of the interleukin-6 receptor antibody tocilizumab in patients with discogenic low back pain. Thirty-two consecutive patients were intradiscally injected with 2 mL of 0.5% bupivacaine (control group). Another 31 consecutive patients were intradiscally injected with 40 mg tocilizumab and 1-2 mL of 0.5% bupivacaine (tocilizumab group) at the same time. Prior to treatment, the vertebral origin of low back pain was confirmed in all patients based on pain provocation during discography and pain relief with 1 mL of 1% xylocaine. Numeric rating scale and Oswestry disability index scores were used to evaluate pain level before and after treatment between the 2 groups. The association between pain relief with tocilizumab and intervertebral disc degeneration grade was also determined. At the end of the study (8 weeks after treatment), 30 patients in each group were evaluable. In the tocilizumab group, numeric rating scale and Oswestry disability index scores improved significantly at 2 and 4 weeks after treatment, respectively. Intervertebral disc degeneration was not associated with improvement of numeric rating scale score in the tocilizumab group. Local infection (i.e., discitis) was observed in 1 patient in the tocilizumab group. The results demonstrate the clinical relevance of interleukin-6 in discogenic low back pain. Intradiscal tocilizumab injection was shown to exert a short-term analgesic effect in patients with discogenic low back pain. Further research is required to determine the long-term effects of intradiscal tocilizumab therapy in patients with discogenic low back pain. Copyright © 2015 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.

  10. Cardiovascular Risk in Hypertension in Relation to Achieved Blood Pressure Using Automated Office Blood Pressure Measurement.

    Science.gov (United States)

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

    2016-10-01

    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.

  11. NORMAL PRESSURE AND FRICTION STRESS MEASUREMENT IN ROLLING PROCESSES

    DEFF Research Database (Denmark)

    Henningsen, Poul; Arentoft, Mogens; Lagergren, Jonas

    2005-01-01

    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...

  12. Photoluminescence excitation measurements using pressure-tuned laser diodes

    Science.gov (United States)

    Bercha, Artem; Ivonyak, Yurii; Medryk, Radosław; Trzeciakowski, Witold A.; Dybała, Filip; Piechal, Bernard

    2015-06-01

    Pressure-tuned laser diodes in external cavity were used as tunable sources for photoluminescence excitation (PLE) spectroscopy. The method was demonstrated in the 720 nm-1070 nm spectral range using a few commercial laser diodes. The samples for PLE measurements were quantum-well structures grown on GaAs and on InP. The method is superior to standard PLE measurements using titanium sapphire laser because it can be extended to any spectral range where anti-reflection coated laser diodes are available.

  13. Photoluminescence excitation measurements using pressure-tuned laser diodes

    International Nuclear Information System (INIS)

    Bercha, Artem; Ivonyak, Yurii; Mędryk, Radosław; Trzeciakowski, Witold A.; Dybała, Filip; Piechal, Bernard

    2015-01-01

    Pressure-tuned laser diodes in external cavity were used as tunable sources for photoluminescence excitation (PLE) spectroscopy. The method was demonstrated in the 720 nm-1070 nm spectral range using a few commercial laser diodes. The samples for PLE measurements were quantum-well structures grown on GaAs and on InP. The method is superior to standard PLE measurements using titanium sapphire laser because it can be extended to any spectral range where anti-reflection coated laser diodes are available

  14. Measurement of digital blood pressure after local cooling

    DEFF Research Database (Denmark)

    Nielsen, S L; Lassen, N A

    1977-01-01

    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....... In patients with primary or secondary Raynaud's phenomenon, the arterial tone showed an abrupt increase that most often led to complete closure of the digital arteries. The pathological response was expressed as an increased threshold temperature or a well-defined closing temperature that showed only small...

  15. Measurement of digital blood pressure after local cooling

    DEFF Research Database (Denmark)

    Nielsen, S L; Lassen, N A

    1977-01-01

    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......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....... In patients with primary or secondary Raynaud's phenomenon, the arterial tone showed an abrupt increase that most often led to complete closure of the digital arteries. The pathological response was expressed as an increased threshold temperature or a well-defined closing temperature that showed only small...

  16. Prospective blood pressure measurement in renal transplant recipients.

    Science.gov (United States)

    David, V G; Yadav, B; Jeyaseelan, L; Deborah, M N; Jacob, S; Alexander, S; Varughese, S; John, G T

    2014-05-01

    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.

  17. Prospective blood pressure measurement in renal transplant recipients

    Directory of Open Access Journals (Sweden)

    V G David

    2014-01-01

    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.

  18. TREATMENT OF HYPERTENSION USING TELEMEDICAL HOME BLOOD PRESSURE MEASUREMENTS

    DEFF Research Database (Denmark)

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

    2015-01-01

    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....... The decrease in daytime ABPM in the intervention group was systolic/diastolic, -8  ± 12/-4 ± 7 mmHg. This did not differ significantly from the control group's -8 ± 13/-4 ± 8 mmHg. An equal number of participants obtained normal daytime ABPM, in the intervention group 17% (31/175) versus control 21% (37....../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...

  19. Intrauterine Telemetry to Measure Mouse Contractile Pressure In Vivo

    Science.gov (United States)

    Rada, Cara C.; Pierce, Stephanie L.; Grotegut, Chad A.; England, Sarah K.

    2015-01-01

    A complex integration of molecular and electrical signals is needed to transform a quiescent uterus into a contractile organ at the end of pregnancy. Despite the discovery of key regulators of uterine contractility, this process is still not fully understood. Transgenic mice provide an ideal model in which to study parturition. Previously, the only method to study uterine contractility in the mouse was ex vivo isometric tension recordings, which are suboptimal for several reasons. The uterus must be removed from its physiological environment, a limited time course of investigation is possible, and the mice must be sacrificed. The recent development of radiometric telemetry has allowed for longitudinal, real-time measurements of in vivo intrauterine pressure in mice. Here, the implantation of an intrauterine telemeter to measure pressure changes in the mouse uterus from mid-pregnancy until delivery is described. By comparing differences in pressures between wild type and transgenic mice, the physiological impact of a gene of interest can be elucidated. This technique should expedite the development of therapeutics used to treat myometrial disorders during pregnancy, including preterm labor. PMID:25867820

  20. Measurement of the pressure pulse from a detonating explosive

    International Nuclear Information System (INIS)

    Bourne, N K; Milne, A M; Biers, R A

    2005-01-01

    A series of experiments has been carried out to determine the pressure pulse exiting from a polymethylmethacrylate (PMMA) plate, of varying thickness, subject to the shock pulse exerted by a detonating charge of fixed mass. This calibration will define a new donor explosive and inert gap material for use in one of the qualification tests for energetic materials, the large scale gap test. The peak pressure was recorded on the central axis of the attenuator using calibrated piezoresistive manganin gauges as a function of the quantity of PMMA applied to the output of the donor charge. The stress history within the PMMA was measured as a function of run distance and the peak pressure plotted against thickness as a calibration. The shock front was known to have curvature and a measurement of this was attempted. The behaviour of the transmitted shock at small gap thicknesses was shown to be anomalous since the front was partially in a reactive and partially within an inert medium

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

    LENUS (Irish Health Repository)

    Sugrue, Michael

    2015-01-01

    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.

  2. Low-speed pressure measurements using a luminescent coating system

    Science.gov (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 Fowler flap, the deck of a Navy amphibious helicopter landing ship model, and a NASCAR racing model at various drafting orientations.

  3. Measurement of local void fraction at elevated temperature and pressure

    International Nuclear Information System (INIS)

    Duncan, D.; Trabold, T.A.

    1993-03-01

    Significant advances have recently been made in analytical and computational methods for the prediction of local thermal-hydraulic conditions in gas/liquid two-phase flows. There is, however, a need for extensive experimental data, for the dual purposes of constitutive relation development and code qualification. There is especially true of systems involving complicated geometries and/or extreme flow conditions for which little, if any, applicable information exists in the open literature. For the tests described in the present paper, a novel electrical probe has been applied to measure the void fraction in atmospheric pressure air/water flows, and steam/water mixtures at high temperature and pressure. The data acquired in the latter experiments are compared with the results of a one-dimensional two-fluid computational analysis

  4. A batch fabricated capacitive pressure sensor with an integrated Guyton capsule for interstitial fluid pressure measurement

    Science.gov (United States)

    Maleki, Teimour; Fogle, Benjamin; Ziaie, Babak

    2011-05-01

    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.

  5. 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.

  6. 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

    1980-01-01

    the skin blood flow cessation external pressure (FCEP) was recorded using intra-dermal [131I-]-antipyrine mixed with histamine in estimating the skin blood flow. The external pressure was measured with an airfilled plastic cushion connected to a mercury manometer. Over a wide range of pressures as obtained...

  7. 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.

    1990-01-01

    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

  8. [Measurements of surface ocean carbon dioxide partial pressure during WOCE

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    This paper discusses the research progress of the second year of research under Measurement of Surface Ocean Carbon Dioxide Partial Pressure During WOCE'' and proposes to continue measurements of underway pCO[sub 2]. During most of the first year of this grant, our efforts to measure pCO[sub 2] on WOCE WHP legs were frustrated by ship problems. The R/V Knorr, which was originally scheduled to carry out the first work on WHP lines P19 and P16 in the southeastem Pacific during the 1990-91 austral summer, was delayed in the shipyard during her mid-life refit for more than a year. In the interim, the smaller R/V Thomas Washington, was pressed into service to carry out lower-latitude portions of WHP lines P16 and P17 during mid-1991 (TUNES Expedition). We installed and operated our underway chromatographic system on this expedition, even though space and manpower on this smaller vessel were limited and no one from our group would be aboard any of the 3 WHP expedition legs. The results for carbon dioxide and nitrous oxide are shown. A map of the cruise track is shown for each leg, marked with cumulative distance. Following each track is a figure showing the carbon dioxide and nitrous oxide results as a function of distance along this track. The results are plotted as dry-gas mole fractions (in ppm and ppb, respectively) in air and in gas equilibrated with surface seawater at a total pressure equal to the barometric pressure. The air data are plotted as a 10-point running mean, and appear as a roughly horizontal line. The seawater data are plotted as individual points, using a 5-point Gaussian smoother. Equal values Of xCO[sub 2] in air and surface seawater indicate air-sea equilibrium.

  9. Measuring and understanding total dissolved gas pressure in groundwater

    Science.gov (United States)

    Ryan, C.; Roy, J. W.; Randell, J.; Castellon, L.

    2009-05-01

    Since dissolved gases are important to a number of aspects of groundwater (e.g. age dating, active or passive bioremediation, greenhouse gas fluxes, understanding biogeochemical processes involving gases, assessing potential impacts of coal bed methane activities), accurate concentration measurements, and understanding of their subsurface behaviour are important. Researchers have recently begun using total dissolved gas pressure (TGP) sensor measurements, more commonly applied for surface water monitoring, in concert with gas composition analyses to estimate more accurate groundwater gas concentrations in wells. We have used hydraulic packers to isolate the well screens where TDP is being measured, and pump tests to indicate that in-well degassing may reduce TDG below background groundwater levels. Thus, in gas-charged groundwater zones, TGPs can be considerably underestimated in the absence of pumping or screen isolation. We have also observed transient decreased TGPs during pumping that are thought to result from ebullition induced when the water table or water level in the well is lowered below a critical hydrostatic pressure.

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

    Directory of Open Access Journals (Sweden)

    Milos R. Popovic

    2007-04-01

    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.

  11. Out-of-office blood pressure: from measurement to control

    Directory of Open Access Journals (Sweden)

    Baguet JP

    2012-05-01

    Full Text Available Jean-Philippe Baguet1,21Department of Cardiology, University Hospital, 2Bioclinic Radiopharmaceutics Laboratory, INSERM U1039, Joseph Fourier University, Grenoble, FranceAbstract: Hypertension is an important risk factor for the development of cardiovascular disease, and is a major cause of morbidity and mortality worldwide. Traditionally, hypertension diagnosis and treatment and clinical evaluations of antihypertensive efficacy have been based on office blood pressure (BP measurements; however, there is increasing evidence that office measures may provide inadequate or misleading estimates of a patient’s true BP status and level of cardiovascular risk. The introduction, and endorsement by treatment guidelines, of 24-hour ambulatory BP monitoring and self (or home BP monitoring has facilitated more reliable and reproducible estimations of true BP, including the identification of white-coat and masked hypertension, and evaluation of BP variability. In addition, ambulatory BP monitoring enables accurate assessment of treatment effectiveness over 24 hours and both ambulatory and self BP monitoring may lead to better tailoring of therapy according to BP profile and concomitant disease. This review describes the clinical benefits and limitations of out-of-office assessments and their applications for effective management of hypertension and attainment of BP control.Keywords: ambulatory, ABPM, SBPM, blood pressure measurement, hypertension

  12. Prospective Comparative Analysis of 4 Different Intraocular Pressure Measurement Techniques and Their Effects on Pressure Readings.

    Science.gov (United States)

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

    2016-10-01

    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, P<0.001). The pairwise post hoc testing showed statistically significant mean differences (P≤0.001) between all techniques except when GAT with fluorescein droplet was compared with TPA (P=0.222). The Bland-Altman analyses showed 95% limits of agreement maximum potential discrepancies in measurement 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.

  13. Simulations of piezoelectric pressure sensor for radial artery pulse measurement

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Abhay B. [Department of Electronic Science, University of Pune, Pune 411 007 (India); Kalange, Ashok E. [Department of Electronic Science, University of Pune, Pune 411 007 (India); Tuljaram Chaturchand College, Baramati 413 102 (India); Bodas, Dhananjay, E-mail: dhananjay.bodas@gmail.co [Center for Nanobio Sciences, Agharkar Research Institute, Pune 411 004 (India); Gangal, S.A. [Department of Electronic Science, University of Pune, Pune 411 007 (India)

    2010-04-15

    A radial artery pulse is used to diagnose human body constitution (Prakruti) in Ayurveda. A system consisting of piezoelectric sensor (22 mm x 12 mm), data acquisition card and LabView software was used to record the pulse data. The pulse obtained from the sensor was noisy, even though signal processing was done. Moreover due to large sized senor accurate measurements were not possible. Hence, a need was felt to develop a sensor of the size of the order of finger tip with a resonant frequency of the order of 1 Hz. A micromachined pressure sensor based on piezoelectric sensing mechanism was designed and simulated using CoventorWare. Simulations were carried out by varying dimensions of the sensor to optimize the resonant frequency, stresses and voltage generated as a function of applied pressure. All simulations were done with pressure ranging of 1-30 kPa, which is the range used by Ayurvedic practitioners for diagnosis. Preliminary work on fabrication of such a sensor was carried out successfully.

  14. Fast pressure measurements for the TMX-U fusion experiment

    International Nuclear Information System (INIS)

    Hunt, A.L.; Coffield, F.E.; Pickles, W.L.

    1982-01-01

    The pressure on the boundary of the Lawrence Livermore National Laboratory's (LLNL) tandem mirror (TMX-U) plasma experiment is difficult to trace for several reasons: (1) the TMX-U boundary is in the high vacuum range (10 -5 to 10 -6 Pa) and requires an ionization gauge; (2) the boundary includes high-energy neutral particles and radiation, so the gauge must be optically baffled from the plasma; (3) the gauge must be shielded from the magnetic flux density of 0.03 T; (4) maximum conductance to the gauge must be preserved so that the time response remains about 1 ms; (5) a fast electrical circuit is required to measure the small ion-current changes at a rate consistent with the geometrical and experimental time constant of 1 ms. We have developed solutions to these limitations, including fast ionization gauge (FIG) circuitry for the remote gauge operation and the CAMAC system for recording the pressure-time history in the TMX-U computer data base. We also give some examples of actual fast pressure histories during plasma operation

  15. Modeling of an implantable device for remote arterial pressure measurement

    Science.gov (United States)

    Miguel, J. A.; Lechuga, Y.; Mozuelos, R.; Martinez, M.

    2013-05-01

    Cardiovascular diseases are the leading causes of illness and death in Europe, having a major impact on healthcare costs. An intelligent stent (e-stent), capable of obtaining and transmitting measurements of physiological parameters, can be a useful tool for real-time monitorization of arterial blockage without patient hospitalization. In this paper, a behavioral model of a pressure sensing-based e-stent is proposed and simulated under several restenosis conditions. Special attention has been given to the need of an accurate fault model, obtained from realistic finite-element simulations, to ensure long-term reliability; particularly for those faults whose behavior cannot be described by usual analytical models.

  16. Non-destructive residual pressure self-measurement method for the sensing chip of optical Fabry-Perot pressure sensor.

    Science.gov (United States)

    Wang, Xue; Wang, Shuang; Jiang, Junfeng; Liu, Kun; Zhang, Xuezhi; Xiao, Mengnan; Xiao, Hai; Liu, Tiegen

    2017-12-11

    We introduce a simple residual pressure self-measurement method for the Fabry-Perot (F-P) cavity of optical MEMS pressure sensor. No extra installation is required and the structure of the sensor is unchanged. In the method, the relationship between residual pressure and external pressure under the same diaphragm deflection condition at different temperatures is analyzed by using the deflection formula of the circular plate with clamped edges and the ideal gas law. Based on this, the residual pressure under the flat condition can be obtained by pressure scanning process and calculation process. We carried out the experiment to compare the residual pressures of two batches MEMS sensors fabricated by two kinds of bonding process. The measurement result indicates that our approach is reliable enough for the measurement.

  17. Measurement component technology. Volume 1: Cryogenic pressure measurement technology, high pressure flange seals, hydrogen embrittlement of pressure transducer material, close coupled versus remote transducer installation and temperature compensation of pressure transducers

    Science.gov (United States)

    Hayakawa, K. K.; Udell, D. R.; Iwata, M. M.; Lytle, C. F.; Chrisco, R. M.; Greenough, C. S.; Walling, J. A.

    1972-01-01

    The results are presented of an investigation into the availability and performance capability of measurement components in the area of cryogenic temperature, pressure, flow and liquid detection components and high temperature strain gages. In addition, technical subjects allied to the components were researched and discussed. These selected areas of investigation were: (1) high pressure flange seals, (2) hydrogen embrittlement of pressure transducer diaphragms, (3) The effects of close-coupled versus remote transducer installation on pressure measurement, (4) temperature transducer configuration effects on measurements, and (5) techniques in temperature compensation of strain gage pressure transducers. The purpose of the program was to investigate the latest design and application techniques in measurement component technology and to document this information along with recommendations for upgrading measurement component designs for future S-2 derivative applications. Recommendations are provided for upgrading existing state-of-the-art in component design, where required, to satisfy performance requirements of S-2 derivative vehicles.

  18. Measurements and modeling of VLLE at elevated pressures

    DEFF Research Database (Denmark)

    Laursen, Torben

    and pure component calibration. Samples from the different liquid phases in the high-pressure cell is taken using a moveable needle. The systems investigated have been a combination of the components: CO2, N2, di-methyl ether (DME), water, methanol, ethanol and 1-propanol. 41 isotherms have been measured...... has traditionally been considered very time consuming. This work aims at developing and operating an equipment which allows routine measurements of both VLE and VLLE, in the temperature range of 25-45°C and pressure range of 1-100 bar. This has been done by taking advantage of on-line sampling...... and of these 18 were VLLE systems and 32 have not previously been published. Some of the experimental results have been modelled using an equation of state, SRK combined with the MHV1 mixing rule for the a-parameter and the NRTL model for the Gibbs excess energy. The Mathias-Copeman model was used...

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    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...... 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...

  20. Quantitative Thermochemical Measurements in High-Pressure Gaseous Combustion

    Science.gov (United States)

    Kojima, Jun J.; Fischer, David G.

    2012-01-01

    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.

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

    Science.gov (United States)

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

    2007-07-01

    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.

  2. 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

    1990-01-01

    pressure measurements via direct puncture. Furthermore, no significant difference was seen between pancreatic duct and tissue fluid pressure. The technical evaluation was performed by repeated pressure measurements in human pancreatic autopsy specimens and living rats in a pressure chamber at various...

  3. Gaseous Multiplication factor measurements on low pressure ethylene

    International Nuclear Information System (INIS)

    Hevia Vives, Alberto

    2008-01-01

    The present investigation consists of a study of a Proportional Counter considered as a fundamental part of an Absolute Neutron Dosimeter developed for the Chilean Nuclear Energy Commission. The proportional counter consists of a Polyethylene Cathode of approximately 5 cm in diameter and an Anode consisting of a central wire of 5 μm in diameter. The proportional counter is biased at 650 V. The gas pressure ranges from 12 to 36 Torr of pure Ethylene. The work comes up as a need to obtain gas gain curves (Gas Multiplication Factors) for the proportional counter operated in the conditions as mentioned. This is a consequence of the scarcity of the existing information referred to Ethylene for the range of bias and gas pressure required in this case. Likewise, the research involved in this study contributed with useful information for the institution involved in the design and construction of the neutron dosimeter, as well as for the scientific community through the publication of this work. The results were obtained by using the above-mentioned Neutron Dosimeter but instead of using recoil protons by fast neutrons, the measurements were completed by directly using a 241 Am alpha particle source installed inside the dosimeter. The analysis of results as well as a detailed study of the pulse shapes provided by the proportional counter was performed by using the well-known MathCAD software. This software contains a text interface that includes symbolic and numeric calculations. Results of the research show that for the high Reduced Electric Fields ( Sa > 1500 Volts/cmTorr) used throughout the present work, Townsend law is still valid. This law states that the Multiplication Factors may be considered as dependent on the Reduced Electric Field instead of depending on the bias and gas pressure separately

  4. Reliable intraocular pressure measurement using automated radio-wave telemetry

    Directory of Open Access Journals (Sweden)

    Paschalis EI

    2014-01-01

    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

  5. Pressure drop measurements in LMFBR wire wrapped blanket assemblies

    International Nuclear Information System (INIS)

    Chiu, C.; Hawley, J.; Rohsenow, W.M.; Todreas, N.E.

    1977-07-01

    In this experiment, measurements of subchannel static pressure for an interior and edge subchannel were taken at two elevations in two wire-wrapped 61-pin bundles. One of the bundles has geometric characteristics of P/D = 1.067 and H/D = 8.0 (4 inch lead length and 0.501 inch rod diameter) and the other bundle has geometric characteristics of P/D = 1.067 and H/D = 4.0 (2 inch lead length and 0.501 inch rod diameter). The bundle average friction factors as well as the local subchannel friction factors for both interior and edge subchannels were determined from the experimental static pressure data. The average subchannel flow rates for both edge and interior subchannels were determined in a separate experiment. Results show that two correlations suggested by Rehme and Novendstern for the bundle average friction factor cannot predict the data within the range of experimental error. The bundle average friction factors for both bundles under test were underestimated by Rehme's correlation and overestimated by Novendstern's correlation. The results of the local subchannel friction factors indicate the effect of the wire lead length is more pronounced in the interior subchannel friction factor than in the edge subchannel friction factor. As the wire wrap lead length decreases, both interior and edge subchannel friction factors increase

  6. Stress Rupture Life Reliability Measures for Composite Overwrapped Pressure Vessels

    Science.gov (United States)

    Murthy, Pappu L. N.; Thesken, John C.; Phoenix, S. Leigh; Grimes-Ledesma, Lorie

    2007-01-01

    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.

  7. In situ viscosity measurements of albite melt under high pressure

    CERN Document Server

    Funakoshi, K I; Terasaki, H

    2002-01-01

    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.

  8. Extraction of airfoil data using PIV and pressure measurements

    DEFF Research Database (Denmark)

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

    2011-01-01

    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...... 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...... is a reliable tool to extract airfoil data from experimental data. Copyright © 2010 John Wiley & Sons, Ltd....

  9. Experimental measurements of static pressure and pressure drop in a duct enclosing a seven wire-wrapped rod bundle

    International Nuclear Information System (INIS)

    Graca, M.C.; Ballve, H.; Fernandez y Fernandez, E.; Carajilescov, P.

    1981-01-01

    The friction factor and the static pressure distributions, in the axial and transversal directions, in the wall of the hexagonal duct, enclosing a seven wire-wrapped rod bundle, were experimentally measured, using an air opened loop. The Reynolds numbers are the range 10 3 - 5x10 4 . The friction factors are compared to existing correlations. The static pressure distributions show that the static pressure is not hydrostatic in the cross section of the flow. (Author) [pt

  10. Blood pressure measurement in epidemiological investigations in teenagers

    International Nuclear Information System (INIS)

    Coppieters, Yves; Parent, Florence; Berghmans, Luc; Godin, Isabelle; Leveque, Alain

    2001-01-01

    Background: The use of sphygmomanometers may lead to problems in investigations on health of young people. The purpose of this paper is to present the validation of the blood pressure (BP) collected during the survey 'Youth Heart Health' in Hainaut by using second sample of young people in Hainaut for which BP was measured by a manual taking of tension and by an electronic device. Methods: Validation was done with a control sample of 343 young with five successive BP measures: twice with the mercury sphygmomanometer and three with DXL. We compared the manual and the electronic measures in order to study the correlation between the two methods. The control sample was used in order to compare the BP measurements with the results of the survey on the health of young people in Hainaut. Results: The differences between manual systolic BP and Dinamap measures are significant (differences in averages 3.6 mmHg; d.s. 7.8; 95% CI: 2.8-4.4 mmHg; p < 0.001) and the regression coefficient is -0.015. Diastolic BP is significantly higher with the manual method than with Dinamap (differences in means: 8.2 mmHg; d.s. 7.0; 95% CI: 7.4-8.9 mmHg; p < 0.001) and the coefficient of regression is 0.096. We observe a difference in BP between the general survey and the control group (10.3 mmHg for systolic manual control and of 10.9 mmHg for systolic electronic control; 3.3 mmHg for diastolic manual control and of 11.5 mmHg for diastolic electronic control). Conclusions: The values of BP of the 'Youth Heart Health' are significantly higher. These observations indicate the difficulties in the choice of the tool for measurements of BP in epidemiological investigations in the teenagers. In order to decrease skews of observations in the measurement of BP, it is recommended to use a valid electronic instrument. Dinamap XL is an instrument of choice in such studies of young people. Environmental and organisational factors may also explain the observed difference, which means that survey

  11. Urethral pressure reflectometry. A method for simultaneous measurements of pressure and cross-sectional area in the female urethra

    DEFF Research Database (Denmark)

    Klarskov, Niels

    2012-01-01

    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...

  12. CT-guided vertebroplasty in osteoprotic vertebral fractures: incidence of secondary fractures and impact of intradiscal cement leakages during follow-up

    Energy Technology Data Exchange (ETDEWEB)

    Pitton, M.B.; Herber, S.; Bletz, C.; Morgen, N.; Koch, U.; Dueber, C. [University Hospital of Mainz, Johannes Gutenberg University of Mainz, Department of Diagnostic and Interventional Radiology, Mainz (Germany); Drees, P.; Boehm, B. [University Hospital of Mainz, Johannes Gutenberg University of Mainz, Department of Orthopedia, Mainz (Germany); Eckardt, A. [Rheinfelden Hospital, Department of Orthopedic and Trauma Surgery, Rheinfelden (Germany)

    2008-01-15

    The purpose of this study was to analyse the number and types of secondary fractures, and to investigate the impact of intradiscal cement leaks for adjacent vertebral fractures. Patients with osteoporotic vertebral fractures were treated with vertebroplasty. Results were documented and prospectively followed by means of computed tomography (CT) and magnetic resonance imaging. The frequency and the types of cement leakages were analysed from multiplanar CT images and secondary fractures were characterised as follows: (1) adjacent fracture in the immediate vicinity of an augmented vertebra; (2) sandwich fracture, fracture of an untreated vertebra between two vertebrae that had been previously augmented, and (3) distant fractures not in the vicinity of augmented vertebrae. A total of 385 osteoporotic vertebral fractures were treated in 191 patients (61 men, 130 women, age 70.7 {+-} 9.7 years). The overall rate of cement leaks was 55.6%, including all leaks detectable by CT. Intradiscal leaks through the upper, the lower, and both endplates occurred in 18.2%, 6.8%, and 2.6%, respectively. In 39 patients (20.4%), a total of 72 secondary fractures occurred: 30 adjacent fractures in 23 patients (12.0%) with a time to fracture of 2 months [median; 1.0/4.0 months, first/third quartile (Q1/Q3)]; 11 secondary sandwich fractures in 11 patients (5.8%) after 1.5 months (median; 0.25/7.5 months, Q1/Q3); and 31 distant fractures in 20 patients (10.5%) after 5 months (median; 2.0/8.0 months, Q1/Q3). Ten of 30 adjacent fractures occurred in the presence of pre-existing intradiscal cement leaks and 20 where there was no leakage. Six of 11 sandwich fractures occurred in the presence of intradiscal leaks (five leaks in both adjacent disc spaces, one leak in the lower disc space) and five where there was no leakage. The rate of secondary adjacent and non-adjacent fractures is quite similar and there is no specific impact of intradiscal leakages on the occurrence of adjacent secondary

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    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......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...

  14. CARS Diagnostics of High Pressure Combustion - 2. Measurements of NO, H2O and High Pressure Flames

    Science.gov (United States)

    1985-12-01

    R85-956328-F CARS DIAGNOSTICS OF r HIGH PRESSURE COMBUSTION -I MEASUREMENTS OF NO, H 0 AND HIGH PRESSURE FLAMES Final Report J.H. Stufflebeam DTIC I7...High Pressure Flames Final Report ~ 5%~ J. H. Stufflebeam J. A. Shirley December 1985 𔃿** U. S. Army Research Office Contract: DAAG29-83-C-OOO1...ClaIiation, CARS Diagnostics of High Pressure Combustion II 12. PERSONAL AUTHOR(S) Stufflebeam , 7. H., ShirleyJA 113a. TYPE OF REPORT 13b. TIME COVERED

  15. Measurement of residual stresses in alloy 600 pressurizer penetrations

    International Nuclear Information System (INIS)

    Hall, J.F.; Molkenthin, J.P.; Prevey, P.S.; Pathania, R.S.

    1994-01-01

    Alloy 600 penetrations in several pressurized water reactors have experienced primary water stress corrosion cracking near the partial penetration J-welds between the Alloy 600 and the cladding on the inside diameter of the components. The microstructure and tensile properties indicated that the Alloy 600 was susceptible to primary water stress corrosion cracking (PWSCC) providing that a high tensile stress (applied + residual) was present. The residual stress distributions at the inside diameter surface and at different depths below the surface were measured in Alloy 600 nozzle and heater sleeve mockups. Surface residual stresses on the nozzle mockup ranged from -350 to +830 MPa. For the heater sleeve mockup, the surface residual stresses ranged from -330 to +525 MPa. In the areas of high tensile residual stress, for the most part, the residual stresses decreased with increasing depth below the surface. For the nozzle and heater sleeve mockups, the percent cold-world and yield strength as a function of depth were determined. (authors). 12 figs., 4 refs

  16. Treatment of herniated lumbar disc by intradiscal and intraforaminal oxygen-ozone (O2-O3) injection.

    Science.gov (United States)

    Muto, M; Andreula, C; Leonardi, M

    2004-06-01

    We report our experience between May 1996 and May 2003 with 2200 patients affected by low back pain or sciatica due to herniated disk treated by intradiscal and intraforaminal oxygen-ozone injection. The patients received medical and physical therapy before treatment for at least 2 months; the patients with conus-cauda syndrome and hyperalgesic sciatica were excluded. We never performed discography before the treatment that was performed under CT guidance or fluoroscopy. CT provided monitoring of gas distribution in the disk and epidural space. No side effects were recorded at short and long-term follow-up. Clinical results were evaluated with the modified McNab method showing an 80% success rate and 20% failure rate in 1750 patients followed up to 6 months while the success rate dropped down at 75% and failure increased at 25% in 1400 followed up to 18 months. CT showed reduction in the size of the herniated disk in only 63% of the followed patients (420 patients). The failure has been mostly related to: calcified herniated disk; spinal canal stenosis; recurrent herniated disk with epidural fibrosis; small descending herniated disk at the level of the lateral recess. Copyright 2004 Masson, Paris

  17. Intradiscal Glucocorticoid Injection for Patients With Chronic Low Back Pain Associated With Active Discopathy: A Randomized Trial.

    Science.gov (United States)

    Nguyen, Christelle; Boutron, Isabelle; Baron, Gabriel; Sanchez, Katherine; Palazzo, Clémence; Benchimol, Raphaël; Paris, Guillaume; James-Belin, Étienne; Lefèvre-Colau, Marie-Martine; Beaudreuil, Johann; Laredo, Jean-Denis; Béra-Louville, Anne; Cotten, Anne; Drapé, Jean-Luc; Feydy, Antoine; Ravaud, Philippe; Rannou, François; Poiraudeau, Serge

    2017-04-18

    Active discopathy is associated with a specific phenotype of chronic low back pain (LBP). Local inflammation has a role in active discopathy-associated symptoms. To assess the efficacy of a single glucocorticoid intradiscal injection (GC IDI) in patients with chronic LBP with active discopathy. Prospective, parallel-group, double-blind, randomized, controlled study. (ClinicalTrials.gov: NCT00804531). 3 tertiary care centers in France. 135 patients with chronic LBP with active discopathy on magnetic resonance imaging (MRI). A single GC IDI (25 mg prednisolone acetate) during discography (n = 67) or discography alone (n = 68). The primary outcome was the percentage of patients with LBP intensity less than 40 on an 11-point numerical rating scale (0 [no pain] to 100 [maximum pain] in 10-point increments) in the previous 48 hours at 1 month after the intervention. The main secondary outcomes were LBP intensity and persistent active discopathy on MRI at 12 months and spine-specific limitations in activities, health-related quality of life, anxiety and depression, employment status, and use of analgesics and nonsteroidal anti-inflammatory drugs at 1 and 12 months. All randomly assigned patients were included in the primary efficacy analysis. At 1 month after the intervention, the percentage of responders (LBP intensity discopathy, a single GC IDI reduces LBP at 1 month but not at 12 months. French Ministry of Health.

  18. An instrument to measure differential pore pressures in deep ocean sediments: Pop-Up-Pore-Pressure-Instrument (PUPPI)

    International Nuclear Information System (INIS)

    Schultheiss, P.J.; McPhail, S.D.; Packwood, A.R.; Hart, B.

    1985-01-01

    A Pop-Up-Pore-Pressure-Instrument (PUPPI) has been developed to measure differential pore pressures in sediments. The differential pressure is the pressure above or below normal hydrostatic pressure at the depth of the measurement. It is designed to operate in water depths up to 6000 metres for periods of weeks or months, if required, and measures differential pore pressures at depths of up to 3 metres into the sediments with a resolution of 0.05 kPa. It is a free-fall device with a lance which penetrates the sediments. This lance and the ballast weight is disposed when the PUPPI is acoustically released from the sea floor. When combined with permeability and porosity values of deep-sea sediments the pore pressure measurements made using the PUPPI suggest advection velocities as low as 8.8 mm/yr. The mechanical, electrical and acoustic systems are described together with data obtained from both shallow and deep water trials. (author)

  19. Non-invasive measurement of pressure gradients using ultrasound

    DEFF Research Database (Denmark)

    Olesen, Jacob Bjerring; Traberg, Marie Sand; Pihl, Michael Johannes

    2013-01-01

    A non-invasive method for estimating 2-D pressure gradients from ultrasound vector velocity data is presented. The method relies on in-plane vector velocity fields acquired using the Transverse Oscillation method. The pressure gradients are estimated by applying the Navier-Stokes equations...

  20. Reliability of blood pressure measurement and cardiovascular risk prediction

    NARCIS (Netherlands)

    van der Hoeven, N.V.

    2016-01-01

    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

  1. Measuring gait pattern in elderly individuals by using a plantar pressure measurement device.

    Science.gov (United States)

    Nakajima, Kanako; Anzai, Emi; Iwakami, Yumi; Ino, Shuichi; Yamashita, Kazuhiko; Ohta, Yuji

    2014-01-01

    Hip fracture in the elderly is a serious problem, and solutions to prevent falls are needed. This study focused on elucidating data critical to fall prevention by evaluating ambulatory function, and we achieved this by developing a plantar pressure measurement device to determine gait function. Our device enables measurement of gait function in the unrestrained state by transmitting wireless data. In this study, we applied the device to field experiments involving 98 subjects (39 healthy individuals, 44 elderly non-fallers, and 15 elderly fallers). Gait features were determined by measuring the pressure values and foot contact patterns used as gait function parameters in previous studies. In particular, decreased peak pressure values were noted at heel strike and toe off during walking in elderly fallers compared with elderly non-fallers. In addition, compared with healthy subjects, elderly fallers also showed extension of the double support phase, and differences in individual gait pattern features were observed between the groups. Experiments confirmed that our device can be used to obtain the gait features of a diverse group of elderly individuals. Moreover, our device enables objective and quantitative evaluation of gait function and thus may be useful for evaluating gait function in the elderly.

  2. Central venous pulse pressure analysis using an R-synchronized pressure measurement system.

    Science.gov (United States)

    Fujita, Yoshihisa; Hayashi, Daisuke; Wada, Shinya; Yoshioka, Naoki; Yasukawa, Takeshi; Pestel, Gunther

    2006-12-01

    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.

  3. A comparison of blood pressure measurements in newborns.

    LENUS (Irish Health Repository)

    O'Shea, Joyce

    2012-02-01

    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.

  4. Development of a commercial Transducer for Measuring Pressure and Friction on the Model Die Surface

    DEFF Research Database (Denmark)

    Andersen, Claus Bo; Ravn, Bjarne Gottlieb; Wanheim, Tarras

    2001-01-01

    deflection in the tool causes incorrect shape of the final component. The dinemsions of the die-cavity have to be corrected taking into account die deflection due to the high internal pressure. The modelling material technique is suitable for measuring internal pressure, but so far only a transducer...... to measure normal pressure has been available....

  5. Level of Mercury Manometer With Respect to Heart: Does it Affect Blood Pressure Measurement?

    Science.gov (United States)

    Kapoor, Raj; Roy, V K; Manna, S; Bhattacharjee, M

    2015-01-01

    Measurement of blood pressure is an integral part of clinical examination. Over the years various types of instruments have been used to measure blood pressure but till date the mercury sphygmomanometer is regarded as the gold standard. However, there is a myth prevalent among health professionals regarding the level of the manometer in relation to heart at the time of measuring of blood pressure. Many professionals insist that it has to be placed at the level of the heart. We argue that the limb from which pressure is measured must be at the heart level rather than the manometer. We conducted a study in which we measured the blood pressure in adults by placing the manometer at three different levels with respect to the heart. The values of blood pressure obtained at all levels were similar and did not show any statistically significant difference. We therefore conclude that the level of sphygmomanometer per se does not affect blood pressure measurement.

  6. A novel high pressure, high temperature vessel used to conduct long-term stability measurements of silicon MEMS pressure transducers

    Science.gov (United States)

    Wisniewiski, David

    2014-03-01

    The need to quantify and to improve long-term stability of pressure transducers is a persistent requirement from the aerospace sector. Specifically, the incorporation of real-time pressure monitoring in aircraft landing gear, as exemplified in Tire Pressure Monitoring Systems (TPMS), has placed greater demand on the pressure transducer for improved performance and increased reliability which is manifested in low lifecycle cost and minimal maintenance downtime through fuel savings and increased life of the tire. Piezoresistive (PR) silicon MEMS pressure transducers are the primary choice as a transduction method for this measurement owing to their ability to be designed for the harsh environment seen in aircraft landing gear. However, these pressure transducers are only as valuable as the long-term stability they possess to ensure reliable, real-time monitoring over tens of years. The "heart" of the pressure transducer is the silicon MEMS element, and it is at this basic level where the long-term stability is established and needs to be quantified. A novel High Pressure, High Temperature (HPHT) vessel has been designed and constructed to facilitate this critical measurement of the silicon MEMS element directly through a process of mechanically "floating" the silicon MEMS element while being subjected to the extreme environments of pressure and temperature, simultaneously. Furthermore, the HPHT vessel is scalable to permit up to fifty specimens to be tested at one time to provide a statistically significant data population on which to draw reasonable conclusions on long-term stability. With the knowledge gained on the silicon MEMS element, higher level assembly to the pressure transducer envelope package can also be quantified as to the build-effects contribution to long-term stability in the same HPHT vessel due to its accommodating size. Accordingly, a HPHT vessel offering multiple levels of configurability and robustness in data measurement is presented, along

  7. Highway-railway at-grade crossing structures : trackbed and surface pressure measurements and assessments.

    Science.gov (United States)

    2009-05-01

    Techniques are described for installing instrumentation within highway/railway crossings - to measure vertical pressures under moving highway and railway loadings - using earth pressure cells. Also, techniques are described for installing instrumenta...

  8. Does the position or contact pressure of the stethoscope make any difference to clinical blood pressure measurements: an observational study.

    Science.gov (United States)

    Pan, Fan; Zheng, Dingchang; He, Peiyu; Murray, Alan

    2014-12-01

    This study aimed to investigate the effect of stethoscope position and contact pressure on auscultatory blood pressure (BP) measurement. Thirty healthy subjects were studied. Two identical stethoscopes (one under the cuff, the other outside the cuff) were used to simultaneously and digitally record 2 channels of Korotkoff sounds during linear cuff pressure deflation. For each subject, 3 measurements with different contact pressures (0, 50, and 100 mm Hg) on the stethoscope outside the cuff were each recorded at 3 repeat sessions. The Korotkoff sounds were replayed twice on separate days to each of 2 experienced listeners to determine systolic and diastolic BPs (SBP and DBP). Variance analysis was performed to study the measurement repeatability and the effect of stethoscope position and contact pressure on BPs. There was no significant BP difference between the 3 repeat sessions, between the 2 determinations from each listener, between the 2 listeners and between the 3 stethoscope contact pressures (all P > 0.06). There was no significant SBP difference between the 2 stethoscope positions at the 2 lower stethoscope pressures (P = 0.23 and 0.45), but there was a small (0.4 mm Hg, clinically unimportant) significant difference (P = 0.005) at the highest stethoscope pressure. The key result was that, DBP from the stethoscope under the cuff was significantly lower than that from outside the cuff by 2.8 mm Hg (P pressure, this study could suggest that the stethoscope position under the cuff, and closer to the arterial occlusion, might yield measurements closer to the actual invasive DBP.

  9. High pressure cells for magnetic measurements - destruction and functional tests

    Czech Academy of Sciences Publication Activity Database

    Kamarád, Jiří; Machátová, Zuzana; Arnold, Zdeněk

    2004-01-01

    Roč. 75, č. 11 (2004), s. 5022-5025 ISSN 0034-6748 R&D Projects: GA ČR GA202/02/0739; GA AV ČR IAA1010315 Institutional research plan: CEZ:AV0Z1010914 Keywords : pressure cells * pressure transmitting media * CuBe * MP35N Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.226, year: 2004

  10. Pressure Measurement Techniques for Abdominal Hypertension: Conclusions from an Experimental Model.

    Science.gov (United States)

    Chopra, Sascha Santosh; Wolf, Stefan; Rohde, Veit; Freimann, Florian Baptist

    2015-01-01

    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.

  11. Pilot study: Assessing repeatability of the EcoWalk platform resistive pressure sensors to measure plantar pressure during barefoot standing

    International Nuclear Information System (INIS)

    Zequera, Martha; Perdomo, Oscar; Wilches, Carlos; Vizcaya, Pedro

    2013-01-01

    Plantar pressure provides useful information to assess the feet's condition. These systems have emerged as popular tools in clinical environment. These systems present errors and no compensation information is presented by the manufacturer, leading to uncertainty in the measurements. Ten healthy subjects, 5 females and 5 males, were recruited. Lateral load distribution, antero-posterior load distribution, average pressure, contact area, and force were recorded. The aims of this study were to assess repeatability of the EcoWalk system and identify the range of pressure values observed in the normal foot. The coefficient of repeatability was less than 4% for all parameters considered.

  12. Urethral pressure reflectometry. A method for simultaneous measurements of pressure and cross-sectional area in the female urethra

    DEFF Research Database (Denmark)

    Klarskov, Niels

    2012-01-01

    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...... the hysteresis were decreased in stress urinary incontinent (SUI) women compared to continent women. Thus the parameters seem to be relevant regarding SUI. UPR examination was performed before and after urethral bulking and from these examinations a mechanism of action of the bulking procedure was proposed...

  13. Pilot study: Assessing repeatability of the EcoWalk platform resistive pressure sensors to measure plantar pressure during barefoot standing

    Science.gov (United States)

    Zequera, Martha; Perdomo, Oscar; Wilches, Carlos; Vizcaya, Pedro

    2013-06-01

    Plantar pressure provides useful information to assess the feet's condition. These systems have emerged as popular tools in clinical environment. These systems present errors and no compensation information is presented by the manufacturer, leading to uncertainty in the measurements. Ten healthy subjects, 5 females and 5 males, were recruited. Lateral load distribution, antero-posterior load distribution, average pressure, contact area, and force were recorded. The aims of this study were to assess repeatability of the EcoWalk system and identify the range of pressure values observed in the normal foot. The coefficient of repeatability was less than 4% for all parameters considered.

  14. Ultra-sensitive graphene sensor for measuring high vacuum pressure.

    Science.gov (United States)

    Il Ahn, Sung; Ra Jung, Ju; Young Choi, So; Hwa Son, Min; Jin Hong, Yu; Park, Jung-Chul

    2017-10-03

    We demonstrate here that several different graphene nanoribbon (GNR) samples can be separated from the GNR mixture synthesized by conventional methods. The sheet resistance of the purified GNR gradually decreased with decreasing pressure at 30 °C, whereas it increased at 100 °C. A hypothesis based on van der Waals attractive interactions between GNR sheets was introduced to explain this finding. This hypothesis verified by the shifted main peaks in vacuum X-ray diffraction spectra: 0.022 nm and 0.041 nm shifts were observed for reduced graphene oxide (RGO) and GNR, respectively. Theoretical calculations indicated that, for RGO, the shifted distance was similar to the calculated distance. The response of the GNR sensor to pressure changes occurred rapidly (in seconds). The normalized response time of each sample indicated that sensor using GNR reduced the tailing of the response time by shortening the diffusion path of gas molecules. The sensitivity of the GNR sensor was three times that of RGO in the given pressure range. Moreover, the sensitivity of GNR was much larger than those of the most popularly studied pressure sensors using Piezoresistivity, and the sensor could detect vacuum pressures of 8 × 10 -7  Torr.

  15. Oscillometric measurement of systolic and diastolic blood pressures validated in a physiologic mathematical model.

    Science.gov (United States)

    Babbs, Charles F

    2012-08-22

    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. 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. 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. 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.

  16. Oscillometric measurement of systolic and diastolic blood pressures validated in a physiologic mathematical model

    Directory of Open Access Journals (Sweden)

    Babbs Charles F

    2012-08-01

    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.

  17. Glucose Monitoring System Based on Osmotic Pressure Measurements

    Directory of Open Access Journals (Sweden)

    Alexandra LEAL

    2011-02-01

    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.

  18. Studies of Protein Solution Properties Using Osmotic Pressure Measurements

    Science.gov (United States)

    Agena, S.; Bogle, David; Pusey, Marc; Agena, S.

    1998-01-01

    Examination of the protein crystallization process involves investigation of the liquid and solid state and a protein's properties in these states. Liquid state studies such as protein self association in solution by light scattering methods or other methods have been used to examine a protein Is properties and therefore its crystallization process and conditions. Likewise can osmotic pressure data be used to examine protein properties and various published osmotic pressure studies were examined by us to correlate osmotic pressure to protein solution properties. The solution behavior of serum albumin, alpha - chymotrypsin, beta - lactoglobulin and ovalbumin was examined over a range of temperatures, pH values and different salt types and concentrations. Using virial expansion and a local composition model the non ideal solution behavior in form of the activity coefficients (thermodynamic) was described for the systems. This protein activity coefficient data was related to a protein's solubility behavior and this process and the results will be presented.

  19. Risk evaluation on the basis of pressure rate measured by automatic pressure tracking adiabatic calorimeter.

    Science.gov (United States)

    Iwata, Yusaku; Koseki, Hiroshi

    2008-11-15

    An automatic pressure tracking adiabatic calorimeter (APTAC) had been employed to obtain the thermokinetic and the vapor pressure data during runaway reactions. The APTAC is an adiabatic calorimeter with a large-scale sample mass and low thermal inertia, and is an extremely useful tool for assessing thermal hazards of reactive chemicals. The data obtained by the APTAC are important information for the design of the safe industrial process. The thermodynamics parameters and the gas production were discussed on the basis of the experimental data of various concentrations and weights of di-tert-butyl peroxide (DTBP)/toluene solution for the purpose of investigating the properties of the APTAC data. The thermal decomposition of DTBP was studied on the basis of the temperature data and the pressure data obtained by the APTAC. The activation energy and the frequency factor of DTBP are nearly constant and the same as the literature values in the concentrations between 20 and 60 wt.%. The pressure rise due to gas production is important data for designing the relief vent of a reactor. The time history of the gas production was investigated with various weights and concentrations. The total gas production index, which had the vapor pressure correction, was 1.0 in the decomposition of DTBP.

  20. Risk evaluation on the basis of pressure rate measured by automatic pressure tracking adiabatic calorimeter

    International Nuclear Information System (INIS)

    Iwata, Yusaku; Koseki, Hiroshi

    2008-01-01

    An automatic pressure tracking adiabatic calorimeter (APTAC) had been employed to obtain the thermokinetic and the vapor pressure data during runaway reactions. The APTAC is an adiabatic calorimeter with a large-scale sample mass and low thermal inertia, and is an extremely useful tool for assessing thermal hazards of reactive chemicals. The data obtained by the APTAC are important information for the design of the safe industrial process. The thermodynamics parameters and the gas production were discussed on the basis of the experimental data of various concentrations and weights of di-tert-butyl peroxide (DTBP)/toluene solution for the purpose of investigating the properties of the APTAC data. The thermal decomposition of DTBP was studied on the basis of the temperature data and the pressure data obtained by the APTAC. The activation energy and the frequency factor of DTBP are nearly constant and the same as the literature values in the concentrations between 20 and 60 wt.%. The pressure rise due to gas production is important data for designing the relief vent of a reactor. The time history of the gas production was investigated with various weights and concentrations. The total gas production index, which had the vapor pressure correction, was 1.0 in the decomposition of DTBP

  1. Unsteady Surface Pressure Measurements on a Pitching Airfoil

    Science.gov (United States)

    1985-03-12

    through 8 Dynamics 7512B amplifiers. The pitching motions of the airfoil were generated by 6°jN\\! 920O/_ a PDP 11/03 computer controlling a Control...acquisition system. The pressure data were used to calculate pressure 2 coefficients which were in turn integrated to compute lift coefficients. Both...Airfoils," AIAA J., Vol. 13, No. 1, 17. Gormont, R.E., "A Mathenatical Model pp 71-79, Jan 1975. of Unsteady Aerodynamics and Radial 4. McAlister, K.W

  2. [Mobile Health: IEEE Standard for Wearable Cuffless Blood Pressure Measuring Devices].

    Science.gov (United States)

    Zhou, Xia; Wu, Wenli; Bao, Shudi

    2015-07-01

    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.

  3. Study on storage and measurement system of shock-wave pressure

    International Nuclear Information System (INIS)

    Fan Zehui; Tian Zhong; Tang Jian; Yang Jian; Wei Xiangwen; Wang Lihua

    1998-12-01

    The principle, systematic structure of the storage and measurement system of shock-wave pressure and the calibration and application measurement of the system are introduced. The measured results show that the measuring system can be used as a substitute of the traditional pressure measurement system and used for storage and measurement of pressure wave shape of the shock-wave resulted from explosion. It has the following advantages: free of lead-wire, resistant against bad conditions, anti-interference, high reliability, easy calibration and simple measurement procedure, easy to carry, direct communication with micro-computer

  4. Measuring Vapor Pressure with an Isoteniscope: A Hands-on Introduction to Thermodynamic Concepts

    Science.gov (United States)

    Chen, Wenqian; Haslam, Andrew J.; Macey, Andrew; Shah, Umang V.; Brechtelsbauer, Clemens

    2016-01-01

    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…

  5. High Resolution Cluster Pressure Profile Measurements with MUSTANG and Bolocam

    Science.gov (United States)

    Romero, Charles; Mason, Brian S.; Sayers, Jack; Young, Alexander; Dicker, Simon; Mroczkowski, Tony; Reese, Erik D.; Sarazin, Craig L.; Czakon, Nicole G.; Devlin, Mark J.; Korngut, Phillip

    2015-01-01

    Accurate high-resolution intracluster medium (ICM) pressure profiles will help further constrain cosmological parameters as well as baryonic physics in the cores of clusters of galaxies. MUSTANG, a 90 GHz bolometer array on the Green Bank Telescope (GBT) is among the highest resolution (9' FWHM) instruments at 90 GHz, and is among the best instruments to observe the ICM given its sensitivity. We present results from a sub-sample of the Cluster Lensing And Supernova with Hubble (CLASH) clusters of galaxies observed with both MUSTANG and Bolocam. Bolocam, a 150 GHz bolometer array on the CSO with 58' FWHM, and MUSTANG data probe different, and highly complementary, angular (size) scales. We jointly fit spherical electron pressure profiles to the two datasets and find that the addition of the high resolution MUSTANG data can considerably improve constraints on the pressure profiles. A major asset of our fitting algorithm is the ability to uniquely fit for contaminants such as point sources, and thus allowing us to determine the signal from the underlying ICM. We compare our best fit profiles to X-ray determined pressure profiles (provided by ACCEPT), where we find good agreement. Finally we investigate the implications of our results and describe ongoing work to extend this analysis to the full set of CLASH clusters viewable by the GBT, and to obtain even better results with the MUSTANG-1.5 camera

  6. Transient pressure measurements at part load operating condition of ...

    Indian Academy of Sciences (India)

    Hydraulic turbines are operating at part load conditions depending on availability of hydraulic energy or to meet the grid requirements. The turbine experiences ... The present paper focuses on the investigation of a high head model Francis turbine operating at 50% load.Pressure ... University of Technology, Lulea ., Sweden ...

  7. Measures of blood pressure and cognition in dialysis patients

    Science.gov (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...

  8. Simultaneously Measured Interarm Blood Pressure Difference and Stroke: An Individual Participants Data Meta-Analysis.

    Science.gov (United States)

    Tomiyama, Hirofumi; Ohkuma, Toshiaki; Ninomiya, Toshiharu; Mastumoto, Chisa; Kario, Kazuomi; Hoshide, Satoshi; Kita, Yoshikuni; Inoguchi, Toyoshi; Maeda, Yasutaka; Kohara, Katsuhiko; Tabara, Yasuharu; Nakamura, Motoyuki; Ohkubo, Takayoshi; Watada, Hirotaka; Munakata, Masanori; Ohishi, Mitsuru; Ito, Norihisa; Nakamura, Michinari; Shoji, Tetsuo; Vlachopoulos, Charalambos; Yamashina, Akira

    2018-04-09

    We conducted individual participant data meta-analysis to examine the validity of interarm blood pressure difference in simultaneous measurement as a marker to identify subjects with ankle-brachial pressure index blood pressure difference >5 mm Hg as being associated with a significant odds ratio for the presence of ankle-brachial pressure index blood pressure difference >15 mm Hg was associated with a significant Cox stratified adjusted hazard ratio for subsequent stroke (hazard ratio, 2.42; 95% confidence interval, 1.27-4.60; P blood pressure differences, measured simultaneously in both arms, may be associated with vascular damage in the systemic arterial tree. These differences may be useful for identifying subjects with an ankle-brachial pressure index of blood pressure in both arms at the first visit. © 2018 American Heart Association, Inc.

  9. Real-time measurement of needle forces and acute pressure changes during intravitreal injections.

    Science.gov (United States)

    Christensen, Logan; Cerda, Ashlee; Olson, Jeffrey L

    2017-11-01

    The purpose of this study was to use a physiological pressure transducer to measure real-time, continuous pressure changes in an ex vivo study model of porcine eyes to record the amount of force needed for scleral penetration and to measure acute intraocular pressure rise during intravitreal injections. A pressure transducer was inserted into the anterior chamber of 30 fresh porcine eyes, and intraocular pressure was measured 2 s prior to intravitreal injection until 2 s after. A force transducer plate was used to insert various gauge needles into the vitreous cavity and the amount of force in Newtons (N) required for scleral penetration was recorded. For scleral perforation, 32- and 30-gauge needles required 0.44 N and 0.45 N, significantly less than larger gauge needles (P time continuous recordings of pressure reveal that an instantaneous intraocular pressure spike occurs during intravitreal injection and appears to be separate from the intraocular pressure spike that occurs during needle insertion. This pressure spike is transient and has not been captured by previous methods of intraocular pressure measurement, which rely on single time point measurements. The clinical significance of this brief intraocular pressure spike is unclear and warrants further investigation. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

  10. Measurement of vapor pressure of organophosphorous compounds by gas chromatography

    International Nuclear Information System (INIS)

    Panneerselvam, K.; Brahmmananda Rao, C.V.S.; Antony, M.P.

    2016-01-01

    Dialkylalkyl phosphonates have been developed as an alternative solvent to TBP at our laboratory for separation of actinides. Several dialkylalkylphosphonates have been synthesized and the vapor pressure of all of them was determined using Gas Chromatography (GC) technique. In this technique, individual dialkylalkylphosphonates have been separated from a mixture using GC. Gas chromatography has been utilized as a successful technique in determining vapor pressure of homologous series and structurally similar compounds. GC retention time (t a ) is inversely proportional to the vapor pressure of the solute in solution of the stationary phase. This technique strongly depends on the linear correlation observed between 1n(p/p 0 ) of a reference compound and a target sample under investigation, where p is the vapor pressure for reference compound, p 0 = 101.325 kPa, and 1n(t 0 /t a ) where t 0 = 1 minute and t a = difference in retention times of the target compound and a nonretained compound, CH 2 Cl 2 , added. The retention time of reference (trialkyl phosphate) and target (dibutylalkyl phosphonates) compounds along with CH 2 Cl 2 has been obtained by gas chromatograph using a 4 m 10 % XE-60 packed column under isothermal conditions. Helium was used as carrier gas. As expected, the vapor pressure of reference as well as target compounds decreases with increasing molecular weight of organophosphorous compounds. The merits of this technique are its speed, accuracy and tiny volume of sample. Requirement of high purity sample in contrast to the conventional technique is also done away with this technique. (author)

  11. 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)

    1996-06-01

    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).

  12. 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

    2017-01-01

    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.

  13. Agreement between direct and indirect blood pressure measurements obtained from anesthetized Hispaniolan Amazon parrots.

    Science.gov (United States)

    Acierno, Mark J; da Cunha, Anderson; Smith, Julie; Tully, Thomas N; Guzman, David Sanchez-Migallon; Serra, Verna; Mitchell, Mark A

    2008-11-15

    To determine the level of agreement between direct and indirect blood pressure measurements obtained from healthy Hispaniolan Amazon parrots (Amazona ventralis) anesthetized with isoflurane. Validation study. 16 healthy adult Hispaniolan Amazon parrots. Parrots were anesthetized, and a 26-gauge, 19-mm catheter was placed percutaneously in the superficial ulnar artery for direct measurement of systolic, mean, and diastolic arterial pressures. Indirect blood pressure measurements were obtained with a Doppler ultrasonic flow detector and an oscillometric unit. The Bland-Altman method was used to compare direct and indirect blood pressure values. There was substantial disagreement between direct systolic arterial blood pressure and indirect blood pressure measurements obtained with the Doppler detector from the wing (bias, 24 mm Hg; limits of agreement, -37 to 85 mm Hg) and from the leg (bias, 14 mm Hg; limits of agreement, -14 to 42 mm Hg). Attempts to obtain indirect blood pressure measurements with the oscillometric unit were unsuccessful. Results suggested that there was substantial disagreement between indirect blood pressure measurements obtained with a Doppler ultrasonic flow detector in anesthetized Hispaniolan Amazon parrots and directly measured systolic arterial blood pressure.

  14. Field measurement of local ice pressures on the ARAON in the Beaufort Sea

    Directory of Open Access Journals (Sweden)

    Lee Tak-Kee

    2014-12-01

    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.

  15. Field measurement of local ice pressures on the ARAON in the Beaufort Sea

    Science.gov (United States)

    Lee, Tak-Kee; Lee, Jong-Hyun; Kim, Heungsub; Rim, Chae Whan

    2014-12-01

    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.

  16. Unsteady diffuser vane pressure and impeller wake measurements in a centrifugal pump

    Science.gov (United States)

    Arndt, N.; Acosta, A. J.; Brennen, C. E.; Caughey, T. K.

    1987-01-01

    Unsteady surface pressure measurements on a vaned diffuser of a centrifugal pump, and wake measurements of the flow exiting a centrifugal impeller into a vaneless diffuser are presented. Frequency spectra and ensemble averages are given for the unsteady measurements. Two different impellers were used, the pump impeller of the HPOTP (High Pressure Oxygen Turbopump) of the SSME (Space Shuttle Main Engine) and a two-dimensional impeller. The magnitude of the unsteady total pressure measured in the stationary frame at the impeller exit was found to be of the same order of magnitude as the total pressure rise across the pump. The magnitude of the unsteady diffuser vane pressures was observed to be significantly different on suction and pressure side of the vane, attaining its largest value on the suction side the leading edge while decreasing along the vane.

  17. Influence on Calculated Blood Pressure of Measurement Posture for the Development of Wearable Vital Sign Sensors

    Directory of Open Access Journals (Sweden)

    Shouhei Koyama

    2017-01-01

    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.

  18. Arterial blood pressure measurement and pulse wave analysis—their role in enhancing cardiovascular assessment

    International Nuclear Information System (INIS)

    Avolio, Alberto P; Butlin, Mark; Walsh, Andrew

    2010-01-01

    The most common method of clinical measurement of arterial blood pressure is by means of the cuff sphygmomanometer. This instrument has provided fundamental quantitative information on arterial pressure in individual subjects and in populations and facilitated estimation of cardiovascular risk related to levels of blood pressure obtained from the brachial cuff. Although the measurement is taken in a peripheral limb, the values are generally assumed to reflect the pressure throughout the arterial tree in large conduit arteries. Since the arterial pressure pulse becomes modified as it travels away from the heart towards the periphery, this is generally true for mean and diastolic pressure, but not for systolic pressure, and so pulse pressure. The relationship between central and peripheral pulse pressure depends on propagation characteristics of arteries. Hence, while the sphygmomanometer gives values of two single points on the pressure wave (systolic and diastolic pressure), there is additional information that can be obtained from the time-varying pulse waveform that enables an improved quantification of the systolic load on the heart and other central organs. This topical review will assess techniques of pressure measurement that relate to the use of the cuff sphygmomanometer and to the non-invasive registration and analysis of the peripheral and central arterial pressure waveform. Improved assessment of cardiovascular function in relation to treatment and management of high blood pressure will result from future developments in the indirect measurement of arterial blood pressure that involve the conventional cuff sphygmomanometer with the addition of information derived from the peripheral arterial pulse. (topical review)

  19. Measuring Global Surface Pressures on a Circulation Control Concept Using Pressure Sensitive Paint

    Science.gov (United States)

    Watkins, Anthony N.; Lipford, William E.; Leighty, Bradley D.; Goodman, Kyle Z.; Goad, William K.

    2012-01-01

    This report will present the results obtained from the Pressure Sensitive Paint (PSP) technique on a circulation control concept model. This test was conducted at the National Transonic Facility (NTF) at the NASA Langley Research Center. PSP was collected on the upper wing surface while the facility was operating in cryogenic mode at 227 K (-50 oF). The test envelope for the PSP portion included Mach numbers from 0.7 to 0.8 with angle of attack varying between 0 and 8 degrees and a total pressure of approximately 168 kPa (24.4 psi), resulting in a chord Reynolds number of approximately 15 million. While the PSP results did exhibit high levels of noise in certain conditions (where the oxygen content of the flow was very small), some conditions provided good correlation between the PSP and pressure taps, showing the ability of the PSP technique. This work also served as a risk reduction opportunity for future testing in cryogenic conditions at the NTF.

  20. The measurement of digital systolic blood pressure by strain gauge technique

    DEFF Research Database (Denmark)

    Nielsen, P E; Bell, G; Lassen, N A

    1972-01-01

    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...

  1. 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.

    2006-01-01

    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

  2. Accuracy of non-invasive blood pressure measurements in obese patients.

    Science.gov (United States)

    Arnold, Abigail; McNaughton, Amanda

    2018-01-11

    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.

  3. Measuring the collateral network pressure to minimize paraplegia risk in thoracoabdominal aneurysm resection.

    Science.gov (United States)

    Etz, Christian D; Zoli, Stefano; Bischoff, Moritz S; Bodian, Carol; Di Luozzo, Gabriele; Griepp, Randall B

    2010-12-01

    To minimize paraplegia during thoracoabdominal aortic aneurysm repair, the concept of the collateral network was developed. That is, spinal cord perfusion is provided by an interconnecting complex of vessels in the intraspinal, paraspinous, and epidural space and in the paravertebral muscles, including intercostal and lumbar segmental as well as subclavian and hypogastric arteries. Collateral network pressure was measured with a catheter in the distal end of a ligated segmental artery in pigs and human beings. In the pig, collateral network pressure was 75% of the simultaneous mean aortic pressure. With complete segmental arterial ligation, it fell to 27% of baseline, recovering to 40% at 24 hours and 90% at 120 hours. Spinal cord injury occurred in approximately 50% of animals. When all segmental arteries were taken in 2 stages a week apart, collateral network pressure fell only to 50% to 70% of baseline, and spinal cord injury was rare. In human beings, baseline collateral network pressure also was 75% of mean aortic pressure, fell in proportion to the number of segmental arteries ligated, and began recovery within 24 hours. Collateral network pressure was lower with nonpulsatile distal bypass than with pulsatile perfusion. After subtraction of a measure of spinal cord outflow pressure (cerebrospinal fluid pressure or central venous pressure), collateral network pressure provides a clinically useful estimate of spinal cord perfusion pressure. Copyright © 2010. Published by Mosby, Inc.

  4. Capacitive micromachined ultrasonic transducer for ultra-low pressure measurement: Theoretical study

    Science.gov (United States)

    Li, Zhikang; Zhao, Libo; Jiang, Zhuangde; Akhbari, Sina; Ding, Jianjun; Zhao, Yihe; Zhao, Yulong; Lin, Liwei

    2015-12-01

    Ultra-low pressure measurement is necessary in many areas, such as high-vacuum environment monitoring, process control and biomedical applications. This paper presents a novel approach for ultra-low pressure measurement where capacitive micromachined ultrasonic transducers (CMUTs) are used as the sensing elements. The working principle is based on the resonant frequency shift of the membrane under the applied pressure. The membranes of the biased CMUTs can produce a larger resonant frequency shift than the diaphragms with no DC bias in the state-of-the-art resonant pressure sensors, which contributes to pressure sensitivity improvement. The theoretical analysis and finite element method (FEM) simulation were employed to study the relationship between the resonant frequency and the pressure. The results demonstrated excellent capability of the CMUTs for ultra-low pressure measurement. It is shown that the resonant frequency of the CMUT varies linearly with the applied pressure. A sensitivity of more than 6.33 ppm/Pa (68 kHz/kPa) was obtained within a pressure range of 0 to 100 Pa when the CMUTs were biased at a DC voltage of 90% of the collapse voltage. It was also demonstrated that the pressure sensitivity can be adjusted by the DC bias voltage. In addition, the effects of air damping and ambient temperature on the resonant frequency were also studied. The effect of air damping is negligible for the pressures below 1000 Pa. To eliminate the temperature effect on the resonant frequency, a temperature compensating method was proposed.

  5. A viscosity measurement during the high pressure phase transition in triolein

    International Nuclear Information System (INIS)

    Siegoczynski, R M; Rostocki, A J; Kielczynski, P; Szalewski, M

    2008-01-01

    The high-pressure properties of triolein, a subject of extensive research at the Faculty of Physics of Warsaw University of Technology (WUT) have been enhanced by the results of viscosity measurement within the pressure range up to 0.8 GPa. For the measurement the authors have adopted a new ultrasonic method based on Bleustein-Gulyaev waves, successfully developed earlier for the low pressures in the Section of Acoustoelectronics of the Institute of Fundamental Technological Research. The measurements have shown: 1. Exponential rise of viscosity with pressure up to 0.5 GPa. 2. Extraordinary increment of viscosity at constant pressure during phase transition. 3. Further exponential rise of viscosity with pressure of the high-pressure phase of triolein. 4. The pressure exponents of the viscosity of both phases were different (the high-pressure phase had much smaller exponent). 5. The decomposition of the high pressure phase due to the slow decompression have shown very large hysteresis of viscosity on pressure dependence

  6. The measurement for level of marine high-temperature and high-pressure vessels

    International Nuclear Information System (INIS)

    Lin Jie.

    1986-01-01

    The various error factors in measurement for level of marine high-temperature and high-pressure vessels are anslysed. The measuring method of error self compensation and its simplification for land use are shown

  7. Arterial pressure measurement: Is the envelope curve of the oscillometric method influenced by arterial stiffness?

    International Nuclear Information System (INIS)

    Gelido, G; Angiletta, S; Pujalte, A; Quiroga, P; Cornes, P; Craiem, D

    2007-01-01

    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

  8. Intraocular pressure measurement with the Tono-Pen through soft contact lenses.

    Science.gov (United States)

    Panek, W C; Boothe, W A; Lee, D A; Zemplenyi, E; Pettit, T H

    1990-01-15

    We evaluated a miniaturized digital and electronic tonometer, the Tono-Pen, for accuracy of intraocular pressure measurement in the presence of a contact lens. In the manometric study, the Tono-Pen was used to measure a known intraocular pressure, ranging from 10 mm Hg to 60 mm Hg in a cadaver eye over soft contact lenses with different powers and a plano-T bandage lens. There was significant bias in pressure measurement over all contact lenses except for the plano-T, which had no bias at any level. In the clinical study, the intraocular pressures of 40 eyes in 20 normal patients were measured with and without a plano-T contact lens in place. Analysis of variance showed no significant interactive effect between the right and left eyes, with or without the lens. There was no significant difference in the Tono-Pen measurement of intraocular pressure over a plano-T contact lens compared with no lens.

  9. Handcrafted cuff manometers do not accurately measure endotracheal tube cuff pressure.

    Science.gov (United States)

    Annoni, Raquel; de Almeida Junior, Antonio Evanir

    2015-01-01

    To test the agreement between two handcrafted devices and a cuff-specific manometer. The agreement between two handcrafted devices adapted to measure tracheal tube cuff pressure and a cuff-specific manometer was tested on 79 subjects. The cuff pressure was measured with a commercial manometer and with two handcrafted devices (HD) assembled with aneroid sphygmomanometers (HD1 and HD2). The data were compared using Wilcoxon and Spearman tests, the intraclass correlation coefficient (ICC) and limit-of-agreement analysis. Cuff pressures assessed with handcrafted devices were significantly different from commercial device measurements (pressures were higher when measured with HD1 and lower with HD2). The ICCs between the commercial device and HD1 and HD2 were excellent (ICC = 0.8 p manometers do not provide accurate cuff pressure measurements when compared to a cuff-specific device and should not be used to replace the commercial cuff manometers in mechanically ventilated patients.

  10. Calibrating airborne measurements of airspeed, pressure and temperature using a Doppler laser air-motion sensor

    Directory of Open Access Journals (Sweden)

    W. A. Cooper

    2014-09-01

    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.

  11. Differential Intracochlear Sound Pressure Measurements in Human Temporal Bones with an Off-the-Shelf Sensor

    Directory of Open Access Journals (Sweden)

    Martin Grossöhmichen

    2016-01-01

    Full Text Available The standard method to determine the output level of acoustic and mechanical stimulation to the inner ear is measurement of vibration response of the stapes in human cadaveric temporal bones (TBs by laser Doppler vibrometry. However, this method is reliable only if the intact ossicular chain is stimulated. For other stimulation modes an alternative method is needed. The differential intracochlear sound pressure between scala vestibuli (SV and scala tympani (ST is assumed to correlate with excitation. Using a custom-made pressure sensor it has been successfully measured and used to determine the output level of acoustic and mechanical stimulation. To make this method generally accessible, an off-the-shelf pressure sensor (Samba Preclin 420 LP, Samba Sensors was tested here for intracochlear sound pressure measurements. During acoustic stimulation, intracochlear sound pressures were simultaneously measurable in SV and ST between 0.1 and 8 kHz with sufficient signal-to-noise ratios with this sensor. The pressure differences were comparable to results obtained with custom-made sensors. Our results demonstrated that the pressure sensor Samba Preclin 420 LP is usable for measurements of intracochlear sound pressures in SV and ST and for the determination of differential intracochlear sound pressures.

  12. Differential Intracochlear Sound Pressure Measurements in Human Temporal Bones with an Off-the-Shelf Sensor

    Science.gov (United States)

    Salcher, Rolf; Püschel, Klaus; Lenarz, Thomas; Maier, Hannes

    2016-01-01

    The standard method to determine the output level of acoustic and mechanical stimulation to the inner ear is measurement of vibration response of the stapes in human cadaveric temporal bones (TBs) by laser Doppler vibrometry. However, this method is reliable only if the intact ossicular chain is stimulated. For other stimulation modes an alternative method is needed. The differential intracochlear sound pressure between scala vestibuli (SV) and scala tympani (ST) is assumed to correlate with excitation. Using a custom-made pressure sensor it has been successfully measured and used to determine the output level of acoustic and mechanical stimulation. To make this method generally accessible, an off-the-shelf pressure sensor (Samba Preclin 420 LP, Samba Sensors) was tested here for intracochlear sound pressure measurements. During acoustic stimulation, intracochlear sound pressures were simultaneously measurable in SV and ST between 0.1 and 8 kHz with sufficient signal-to-noise ratios with this sensor. The pressure differences were comparable to results obtained with custom-made sensors. Our results demonstrated that the pressure sensor Samba Preclin 420 LP is usable for measurements of intracochlear sound pressures in SV and ST and for the determination of differential intracochlear sound pressures. PMID:27610377

  13. Smartphone-based Continuous Blood Pressure Measurement Using Pulse Transit Time.

    Science.gov (United States)

    Gholamhosseini, Hamid; Meintjes, Andries; Baig, Mirza; Linden, Maria

    2016-01-01

    The increasing availability of low cost and easy to use personalized medical monitoring devices has opened the door for new and innovative methods of health monitoring to emerge. Cuff-less and continuous methods of measuring blood pressure are particularly attractive as blood pressure is one of the most important measurements of long term cardiovascular health. Current methods of noninvasive blood pressure measurement are based on inflation and deflation of a cuff with some effects on arteries where blood pressure is being measured. This inflation can also cause patient discomfort and alter the measurement results. In this work, a mobile application was developed to collate the PhotoPlethysmoGramm (PPG) waveform provided by a pulse oximeter and the electrocardiogram (ECG) for calculating the pulse transit time. This information is then indirectly related to the user's systolic blood pressure. The developed application successfully connects to the PPG and ECG monitoring devices using Bluetooth wireless connection and stores the data onto an online server. The pulse transit time is estimated in real time and the user's systolic blood pressure can be estimated after the system has been calibrated. The synchronization between the two devices was found to pose a challenge to this method of continuous blood pressure monitoring. However, the implemented continuous blood pressure monitoring system effectively serves as a proof of concept. This combined with the massive benefits that an accurate and robust continuous blood pressure monitoring system would provide indicates that it is certainly worthwhile to further develop this system.

  14. 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.

    Science.gov (United States)

    Kiyosawa, Keitaro

    2003-05-01

    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.

  15. When and how should we measure intra- abdominal pressure?

    African Journals Online (AJOL)

    2008-11-11

    Nov 11, 2008 ... IAH is graded from I to IV according to severity, with grade IV being an IAP. ≥25 mmHg. ACS is defined as an IAP >20 mmHg associated with acute organ ... proactive detection by measuring IAP is not common .... Table I. Procedure for measurement of IAP via a urinary catheter using a water manometer.

  16. The number of visits and blood pressure measurements influence the prevalence of high blood pressure in adolescents.

    Science.gov (United States)

    de Oliveira, Luciano Machado Ferreira Tenório; da Silva, Alison Oliveira; Diniz, Paula Rejane Beserra; Farah, Breno Quintella; Pirauá, André Luiz Torres; de Lima Neto, Antônio José; Feitosa, Wallacy Milton do Nascimento; Tassitano, Rafael Miranda; Ritti-Dias, Raphael M

    2017-06-01

    The aim of this study was to analyze the influence of the number of visits and the number of blood pressure (BP) measurements on the prevalence of high blood pressure (HBP) in adolescents. A cross-sectional epidemiologic study with 481 adolescents (14-19 years old) selected using a random cluster sampling strategy. We measured the BP three times in a first visit. Adolescents with HBP performed subsequent visits. The final calculation of BP followed four strategies: the 1st measure, mean of 1st and 2nd measurements, mean of all three measurements, and averaging the 2nd and 3rd measurements. The prevalence of HBP in the first and second visits was 6.4% and 1.9%, and the prevalence of hypertension (after three visits) was 1.7%. The prevalence of HBP varied from 8.6%-18.6% for boys and 4.6%-9.2% for girls, using the average 2nd and 3rd measurements and the 1st measurement, respectively. In all strategies, HBP and hypertension were more prevalent in boys and students attending the nocturnal shift. The number of visits and number of measurements affect the prevalence of HBP and hypertension in adolescents. Thus, clinicians and researchers should consider these aspects when assessing BP in adolescents aged 14-19 years old. Copyright © 2017 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.

  17. Prediction of Pneumonia in Acute Stroke Patients Using Tongue Pressure Measurements.

    Science.gov (United States)

    Nakamori, Masahiro; Hosomi, Naohisa; Ishikawa, Kenichi; Imamura, Eiji; Shishido, Takeo; Ohshita, Tomohiko; Yoshikawa, Mineka; Tsuga, Kazuhiro; Wakabayashi, Shinichi; Maruyama, Hirofumi; Matsumoto, Masayasu

    2016-01-01

    Swallowing dysfunction caused by stroke is a risk factor for aspiration pneumonia. Tongue pressure measurement is a simple and noninvasive method for evaluating swallowing dysfunction. We have hypothesized that low tongue pressure may be able to predict pneumonia occurrence in acute stroke patients. Tongue pressure was measured using balloon-type equipment in 220 acute stroke patients. The modified Mann Assessment of Swallowing Ability (MASA) score was evaluated independently on the same day. Tongue pressure was measured every week thereafter. An improvement in tongue pressure was observed within the first 2 weeks. Receiver operating curve analysis was performed to determine the ability of tongue pressure to predict modified MASA score tongue pressure was 21.6 kPa (χ2 = 45.82, ptongue pressure was significantly lower in patients with pneumonia than in those without pneumonia. Using a Cox proportional hazard model for pneumonia onset with a cutoff tongue pressure value of 21.6 kPa and adjustment for age, sex, and National Institutes of Health Stroke Scale score at admission, the tongue pressure had additional predictive power for pneumonia onset (hazard ratio, 7.95; 95% confidence interval, 2.09 to 52.11; p = 0.0013). In the group with low tongue pressure, 27 of 95 patients showed improvement of tongue pressure within 2 weeks. Pneumonia occurred frequently in patients without improvement of tongue pressure, but not in patients with improvement (31/68 and 2/27, pTongue pressure is a sensitive indicator for predicting pneumonia occurrence in acute stroke patients.

  18. A family of fiber-optic based pressure sensors for intracochlear measurements

    Science.gov (United States)

    Olson, Elizabeth S.; Nakajima, Hideko H.

    2015-02-01

    Fiber-optic pressure sensors have been developed for measurements of intracochlear pressure. The present family of transducers includes an 81 μm diameter sensor employing a SLED light source and single-mode optic fiber, and LED/multi-mode sensors with 126 and 202 μm diameter. The 126 μm diameter pressure sensor also has been constructed with an electrode adhered to its side, for coincident pressure and voltage measurements. These sensors have been used for quantifying cochlear mechanical impedances, informing our understanding of conductive hearing loss and its remediation, and probing the operation of the cochlear amplifier.

  19. Strain measurement in and analysis for hydraulic test of CPR1000 reactor pressure vessel

    International Nuclear Information System (INIS)

    Zhou Dan; Zhuang Dongzhen

    2013-01-01

    The strain measurement in hydraulic test of CPR1000 reactor pressure vessel performed in Dongfang Heavy Machinery Co., Ltd. is introduced. The detail test scheme and method was introduced and the measurement results of strain and stress was given. Meanwhile the finite element analysis was performed for the pressure vessel, which was generally matched with the measurement results. The reliability of strain measurement was verified and the high strength margin of vessel was shown, which would give a good reference value for the follow-up hydraulic tests and strength analysis of reactor pressure vessel. (authors)

  20. Non-destructive estimation of root pressure using sap flow, stem diameter measurements and mechanistic modelling.

    Science.gov (United States)

    De Swaef, Tom; Hanssens, Jochen; Cornelis, Annelies; Steppe, Kathy

    2013-02-01

    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.

  1. 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

    2012-01-01

    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...

  2. 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

    2009-01-01

    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.

  3. Deployment of a Pressure Sensitive Paint System for Measuring Global Surface Pressures on Rotorcraft Blades in Simulated Forward Flight

    Science.gov (United States)

    Watkins, A. Neal; Leighty, Bradley; Lipford, William E.; Wong, Oliver D.; Goodman, Kyle Z.; Crafton, Jim; Forlines, Alan; Goss, Larry P.; Gregory, James W.; Juliano, Thomas J.

    2012-01-01

    This paper will present details of a Pressure Sensitive Paint (PSP) system for measuring global surface pressures on the tips of rotorcraft blades in simulated forward flight at the 14- x 22-Foot Subsonic Tunnel at the NASA Langley Research Center. The system was designed to use a pulsed laser as an excitation source and PSP data was collected using the lifetime-based approach. With the higher intensity of the laser, this allowed PSP images to be acquired during a single laser pulse, resulting in the collection of crisp images that can be used to determine blade pressure at a specific instant in time. This is extremely important in rotorcraft applications as the blades experience dramatically different flow fields depending on their position in the rotor disk. Testing of the system was performed using the U.S. Army General Rotor Model System equipped with four identical blades. Two of the blades were instrumented with pressure transducers to allow for comparison of the results obtained from the PSP. Preliminary results show that the PSP agrees both qualitatively and quantitatively with both the expected results as well as with the pressure taps. Several areas of improvement have been indentified and are currently being developed.

  4. Indirect measurement of near-surface velocity and pressure fields based on measurement of moving free surface profiles

    International Nuclear Information System (INIS)

    Sibamoto, Yasuteru; Nakamura, Hideo

    2005-01-01

    A non-intrusive technique for measurement of the velocity and pressure fields adjacent to a moving fluid surface is developed. The technique is based on the measurement of fluid surface profile. The velocity and pressure fields are derived with use of the boundary element method (BEM) by seeking for an incompressible flow field that satisfies the kinematic boundary condition imposed by the time-dependent fluid surface profile. The proposed technique is tested by deriving the velocity and pressure fields inversely from the fluid surface profiles obtained by a forward BEM calculation of fluid surface response to externally-imposed pressure. The inverse calculation results show good agreement with the imposed pressure distribution in the forward calculation. (author)

  5. Correlation and spectral measurements of fluctuating pressures and velocities in annular turbulent flow. [PWR; BWR

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, R.J.; Jones, B.G.; Roy, R.P.

    1980-02-01

    An experimental study of the fluctuating velocity field, the fluctuating static wall pressure and the in-stream fluctuating static pressure in an annular turbulent air flow system with a radius ratio of 4.314 has been conducted. The study included direct measurements of the mean velocity profile, turbulent velocity field; fluctuating static wall pressure and in-stream fluctuating static pressure from which the statistical values of the turbulent intensity levels, power spectral densities of the turbulent quantities, the cross-correlation between the fluctuating static wall pressure and the fluctuating static pressure in the core region of the flow and the cross-correlation between the fluctuating static wall pressure and the fluctuating velocity field in the core region of the flow were obtained.

  6. PIEZOELECTRIC WAVEGUIDE SENSOR FOR MEASURING PULSE PRESSURE IN CLOSED LIQUID VOLUMES AT HIGH VOLTAGE ELECTRIC DISCHARGE

    Directory of Open Access Journals (Sweden)

    V. G. Zhekul

    2017-10-01

    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

  7. Dynamic response of liquid-filled catheter systems for measurement of blood pressure: precision of measurements and reliability of the Pressure Recording Analytical Method with different disposable systems.

    Science.gov (United States)

    Romagnoli, Stefano; Romano, Salvatore Mario; Bevilacqua, Sergio; Lazzeri, Chiara; Gensini, Gian Franco; Pratesi, Carlo; Quattrone, Diego; Dini, Daniele; De Gaudio, Angelo Raffaele

    2011-08-01

    We aimed to compare the effects of a blood pressure transducer system specifically manufactured to limit underdamping artifacts with those of a standard system on hemodynamic parameter estimation and accuracy. Forty-three consecutive patients undergoing vascular surgery at the University of Florence, Italy, were included. Arterial blood pressure signal was simultaneously registered with 2 MostCare monitors, connected to the artery either by a standard transducer or a specific transducer manufactured to avoid underdamping artifacts (Resonance Over-Shoot Eliminator [R.O.S.E.]; Becton Dickinson, Becton Drive, NJ). Patients were divided into 2 groups: absence (C group) or presence (R group) of underdamping/resonance artifacts of blood pressure signal. Systolic blood pressure, cardiac index, maximal pressure/time ratio (dP/dt(MAX)), and cardiac cycle efficiency were recorded every 30 seconds for 30 minutes. A total of 2675 measurements were performed with 34.9% incidence of underdamping/resonance artifacts. All hemodynamic parameters showed clinically acceptable differences in the C group; in contrast, the results differed greatly in the R group between standard and R.O.S.E. transducer (systolic blood pressure bias, 16.7 mm Hg; cardiac index bias, 0.24 L min(-1) m(-2); dP/dt(MAX) bias, 0.92 mm Hg/ms; cardiac cycle efficiency bias, 0.018 units). Underdamping/resonance artifacts frequently affect blood pressure measurement in operating rooms and intensive care units and cause severe overestimation of systolic blood pressure and incorrect estimation of hemodynamic parameters when the pulse contour method is used. Copyright © 2011 Elsevier Inc. All rights reserved.

  8. Reproduction of pressure field in ultrasonic-measurement-integrated simulation of blood flow.

    Science.gov (United States)

    Funamoto, Kenichi; Hayase, Toshiyuki

    2013-07-01

    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.

  9. Pressure Regulator With Internal Ejector Circulation Pump, Flow and Pressure Measurement Porting, and Fuel Cell System Integration Options

    Science.gov (United States)

    Vasquez, Arturo

    2011-01-01

    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

  10. Effect of instantaneous rotational speed on the analysis of measured diesel engine cylinder pressure data

    International Nuclear Information System (INIS)

    Antonopoulos, Antonis K.; Hountalas, Dimitrios T.

    2012-01-01

    Highlights: ► The effect of in-cycle speed fluctuation on cylinder pressure measurement is investigated. ► A phasing error is introduced when sampling cylinder pressure at constant time intervals. ► The phasing error increases with the increase of engine load and decrease of engine speed. ► Measurement using constant sampling rate affects estimation of HRR, ignition angle etc. - Abstract: Diesel engine cylinder pressure measurements are widely used in field and lab applications to support among other control, monitoring and diagnostic applications. There are two methods to measure cylinder pressure, the use of a crank angle encoder, which guarantees pressure samples at fixed crank angles, and the use of constant time sampling rate. The last is frequently used due to its simplicity or because of practical restrictions. However, in order to perform thermodynamic calculations it is necessary to attribute a crank angle value to each measured pressure value. But if the in-cycle rotational speed fluctuates and this is neglected, an error will result in the values derived from the processing of the measured cylinder pressure. For this reason in the present work an experimental investigation is conducted on a single cylinder diesel test engine to identify the aforementioned problem. During the tests cylinder pressure and instantaneous speed were recorded using an accurate crank angle reference. These where then used to simulate the measurement of cylinder pressure digitized using a fixed time step. The comparison of the two cylinder pressure traces and the thermodynamic parameters derived from them, reveals the introduction of an error which depends on engine load and speed.

  11. Development and application of the condom catheter method for non-invasive measurement of bladder pressure

    Directory of Open Access Journals (Sweden)

    R van Mastrigt

    2009-01-01

    Full Text Available Objectives: A non-invasive method to measure the bladder pressure in males using a condom catheter has been developed. The measurement technique, its validation and limitations, a diagnostic nomogram to non-invasively diagnose bladder outlet obstruction (BOO, and results of large-scale application are discussed. Methods: Modified incontinence condoms are attached to the penis. During voiding the flow of urine is mechanically interrupted. The subsequent maximum pressure in the condom reflects the isovolumetric bladder pressure. The method was validated in a group of 46 patients with lower urinary tract symptoms who were simultaneously studied invasively and non-invasively. Subsequently it was applied in a non-invasive epidemiological study in 1020 healthy males. Results: The reproducibility of the measured isovolumetric bladder pressure is comparable to that of conventional pressure-flow parameters. The measured pressure can be used to diagnose bladder outlet obstruction with a diagnostic accuracy (Area Under receiver operator characteristic curve of 0.98, which compares most favorably with the area under the curve of 0.79 of Q max in the same population. During condom catheter measurements, both the involuntary interruption of voiding and the forced diuresis increase post-void residual volume. This increase does not affect the accuracy of the pressure measurements. Conclusions: We conclude that in males bladder pressure can successfully be measured non-invasively using the condom catheter method. By combining the measured volumetric bladder pressure with a separately measured free flow rate, BOO can non-invasively and accurately be diagnosed.

  12. Avaliação prospectiva dos resultados a longo prazo da terapia intradiscal percutânea lombar por radiofrequência Evaluación prospectiva de resultados a largo plazo de la terapia intradiscal percutánea lumbar con radiofrecuencia Prospective evaluation of long-term results of percutaneous lumbar intradiscal radiofrequency therapy

    Directory of Open Access Journals (Sweden)

    Daniel Ferreira Ghedini

    2011-01-01

    Full Text Available OBJETIVO: Avaliar os resultados do tratamento da lombalgia crônica discogênica com a técnica IDET (Intradiscal Electrothermal Therapy em um acompanhamento maior que dois anos de pós-operatório (PO. MÉTODOS: Estudo prospectivo, avaliando 23 pacientes consecutivos com diagnóstico de lombalgia crônica discogênica tratados com IDET entre fevereiro de 2003 e fevereiro de 2006. A dor foi considerada discogênica em caso de discografia positiva ou imagem compatível com a ressonância magnética, segundo os critérios de Horton e Daftari. Os parâmetros clínicos (EVA e Oswestry foram avaliados no pré-operatório, no retorno com 6, 12, 18, 24 e mais de 48 meses de pós-operatório. RESULTADOS: A média de idade dos pacientes foi de 42,09 (variação de 26 a 51 anos. A média do período do acompanhamento foi de 32,55 meses (variação de 6 a 68 meses. A média do índice de dor (EVA foi de 7,07 ± 1,90, reduzindo-se para 2,47 ±1,876 em 6 meses, 2,69 ±1,82 em 12 meses, 3,63 ±1,75 em 18 meses e 5,73 ±2,12 em 24 meses. A média do índice Oswestry foi de 39,26 ± 11,96 no pré-operatório, reduzindo-se para 19,44±15,72 em 6 meses, 19,8 8 ±15,45 em 12 meses, 26,62 ±13,84 em 18 meses e 31,87 ±14,94 em 24 meses. Os resultados não se mantiveram no acompanhamento de 48 meses. CONCLUSÃO: O IDET mostrou resultados satisfatórios como alternativa paliativa no controle da dor e da incapacidade funcional num período de 24 meses. Os bons resultados deterioraram-se com 48 meses e houve uma tendência de retorno à sintomatologia inicial.OBJETIVO: Evaluar los resultados del tratamiento del lumbago crónico del disco usando la técnica IDET (electrotermocoagulación intradiscal en un seguimiento mayor que dos años de pos operatorio. MÉTODO: Estudio prospectivo, evaluando 23 pacientes, consecutivamente, con diagnóstico de lumbago crónico del disco tratados con IDET desde febrero de 2003 hasta febrero de 2006. El disco fue considerado como siendo

  13. Shock-compression measurements at pressures greater than 1 TPa

    International Nuclear Information System (INIS)

    Ragan, C.E.

    1981-01-01

    Precise Hugoniot data were obtained for samples of aluminum, quartz, iron, molybdenum, and low-density molybdenum (rho 0 = 8.29 g-cm -3 ) using the impedance-matching technique. An underground nuclear explosion drove a nearly planar, 5-TPa shock into a molybdenum standard. Shock velocities were measured with 1.5% to 2.5% accuracies

  14. Measurement error in pressure-decay leak testing

    International Nuclear Information System (INIS)

    Robinson, J.N.

    1979-04-01

    The effect of measurement error in presssure-decay leak testing is considered, and examples are presented to demonstrate how it can be properly accomodated in analyzing data from such tests. Suggestions for more effective specification and conduct of leak tests are presented

  15. Clinical aviation medicine research : comparison of simultaneous measurements of intra-aortic and auscultatory blood pressures with pressure-flow dynamics during rest and excercise.

    Science.gov (United States)

    1966-10-01

    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...

  16. Comparing Pore-scale and Macro-scale Capillary Pressure Measurements Using a Two- dimensional Micromodel

    Science.gov (United States)

    Brown, K. I.; Porter, M. L.; Wildenschild, D.

    2007-12-01

    Capillary pressure plays a critical role in multiphase flow and transport in porous media. At the pore scale, capillary pressure is defined by Laplace's law which states that capillary pressure is a function of surface tension, contact angle and curvature. This study focuses on imaging and estimating pore scale properties that determine capillary pressure. Drainage and imbibition experiments for a NAPL-water system are conducted in a two-dimensional micro-scale porous medium. High resolution images of the phase distributions and associated interfaces within the pores are collected during the experiments. Images are taken at a rate of approximately 50 frames per second with a resolution between 1-10 ìm per pixel. In addition, the pressure in each phase is measured with a transducer outside the porous medium, and pressure-saturation curves are plotted from the data. We will attempt to use Laplace's Law to estimate the average pressure inside the porous medium based on measured curvatures. The two pressure values (measured outside the system versus calculated via Laplace's Law) will be compared. The images will allow for investigation of pore scale properties during dynamic flow conditions, as well as static conditions, and importantly, allow for comparison among the two situations. Specifically, relaxation of menisci interfaces and resulting changes in interface curvature, and thus capillary pressure, will be correlated to variations in system properties such as fluid-fluid viscosities and flow rates.

  17. High temperature and high pressure gas cell for quantitative spectroscopic measurements

    DEFF Research Database (Denmark)

    Christiansen, Caspar; Stolberg-Rohr, Thomine; Fateev, Alexander

    2016-01-01

    A high temperature and high pressure gas cell (HTPGC) has been manufactured for quantitative spectroscopic measurements in the pressure range 1-200 bar and temperature range 300-1300 K. In the present work the cell was employed at up to 100 bar and 1000 K, and measured absorption coefficients...... of a CO2-N2 mixture at 100 bar and 1000 K are revealed for the first time, exceeding the high temperature and pressure combinations previously reported. This paper discusses the design considerations involved in the construction of the cell and presents validation measurements compared against simulated...

  18. Pico Gauges for Minimally Invasive Intracellular Hydrostatic Pressure Measurements1[C][W][OPEN

    Science.gov (United States)

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

    2014-01-01

    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

  19. Measurement of hepatic venous pressure gradient revisited: Catheter wedge vs balloon wedge techniques

    Directory of Open Access Journals (Sweden)

    S Timothy Chelliah

    2011-01-01

    Full Text Available Aims: To evaluate the accuracy of measurement of hepatic venous pressure gradient by catheter wedge as compared to balloon wedge (the gold standard. Materials and Methods: Forty-five patients having a clinical diagnosis of intrahepatic portal hypertension were subjected to the two different types of pressure measurements (catheter wedge and balloon wedge during transjugular liver biopsy under fluoroscopic guidance. Statistical Analysis: Spearman′s rank correlation coefficient, Bland-Altman plot for agreement, and single measure intraclass correlation were used for analysis of data. Results: There was a close correlation between the results obtained by both the techniques, with highly significant concordance (P < 0.0001. Hepatic venous pressure gradients as measured by the catheter wedge technique were either equal to or less than those obtained by the balloon wedge technique. Conclusions: The difference in hepatic venous pressure gradients measured by the two techniques is insignificant.

  20. Measurements of Heat Transfer, Flow, and Pressures in a Simulated Turbine Blade Internal Cooling Passage

    Science.gov (United States)

    Russell, Louis M.; Thurman, Douglas R.; Poinsatte, Philip E.; Hippensteele, Steven A.

    1998-01-01

    An experimental study was made to obtain quantitative information on heat transfer, flow, and pressure distribution in a branched duct test section that had several significant features of an internal cooling passage of a turbine blade. The objective of this study was to generate a set of experimental data that could be used for validation of computer codes that would be used to model internal cooling. Surface heat transfer coefficients and entrance flow conditions were measured at nominal entrance Reynolds numbers of 45,000, 335,000, and 726,000. Heat transfer data were obtained by using a steady-state technique in which an Inconel heater sheet is attached to the surface and coated with liquid crystals. Visual and quantitative flow-field data from particle image velocimetry measurements for a plane at midchannel height for a Reynolds number of 45,000 were also obtained. The flow was seeded with polystyrene particles and illuminated by a laser light sheet. Pressure distribution measurements were made both on the surface with discrete holes and in the flow field with a total pressure probe. The flow-field measurements yielded flow-field velocities at selected locations. A relatively new method, pressure sensitive paint, was also used to measure surface pressure distribution. The pressure paint data obtained at Reynolds numbers of 335,000 and 726,000 compared well with the more standard method of measuring pressures by using discrete holes.

  1. Highly sensitive contact pressure measurements using FBG patch in endotracheal tube cuff

    Science.gov (United States)

    Correia, R.; Blackman, O. R.; Hernandez, F. U.; Korposh, S.; Morgan, S. P.; Hayes-Gill, B. R.; James, S. W.; Evans, D.; Norris, A.

    2016-05-01

    A method for measuring the contact pressure between an endotracheal tube cuff and the trachea was designed and developed by using a fibre Bragg grating (FBG) based optical fibre sensor. The FBG sensor is encased in an epoxy based UV-cured cuboid patch and transduces the transversely loaded pressure into an axial strain that induces wavelength shift of the Bragg reflection. The polymer patch was created by using a PTFE based mould and increases tensile strength and sensitivity of the bare fibre FBG to pressure to 2.10×10-2 nm/kPa. The characteristics of the FBG patch allow for continuous measurement of contact pressure. The measurement of contact pressure was demonstrated by the use of a 3D printed model of a human trachea. The influence of temperature on the measurements is reduced significantly by the use of a second FBG sensor patch that is not in contact with the trachea. Intracuff pressure measurements performed using a commercial manometer agreed well with the FBG contact pressure measurements.

  2. Blood pressure measurement of all five fingers by strain gauge plethysmography

    DEFF Research Database (Denmark)

    Hirai, M; Nielsen, S L; Lassen, N A

    1976-01-01

    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...

  3. Including Pressure Measurements in Supervision of Energy Efficiency of Wastewater Pump Systems

    DEFF Research Database (Denmark)

    Larsen, Torben; Arensman, Mareike; Nerup-Jensen, Ole

    2016-01-01

    energy). This article presents a method for a continuous supervision of the performance of both the pump and the pipeline in order to maintain the initial specific energy consumption as close as possible to the original value from when the system was commissioned. The method is based on pressure...... measurements only. The flow is determined indirectly from pressure fluctuations during pump run-up....

  4. 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.

    2002-01-01

    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

  5. Nurse-measured or ambulatory blood pressure in routine hypertension care

    NARCIS (Netherlands)

    Veerman, D. P.; van Montfrans, G. A.

    1993-01-01

    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

  6. Pressure/cross-sectional area probe in the assessment of urethral closure function. Reproducibility of measurement

    DEFF Research Database (Denmark)

    Lose, G; Schroeder, T

    1990-01-01

    -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...

  7. High- and low-pressure pneumotachometers measure respiration rates accurately in adverse environments

    Science.gov (United States)

    Fagot, R. J.; Mc Donald, R. T.; Roman, J. A.

    1968-01-01

    Respiration-rate transducers in the form of pneumotachometers measure respiration rates of pilots operating high performance research aircraft. In each low pressure or high pressure oxygen system a sensor is placed in series with the pilots oxygen supply line to detect gas flow accompanying respiration.

  8. A new method to normalize plantar pressure measurements for foot size and foot progression angle.

    NARCIS (Netherlands)

    Keijsers, N.L.; Stolwijk, N.M.; Nienhuis, B.; Duysens, J.E.J.

    2009-01-01

    Plantar pressure measurement provides important information about the structure and function of the foot and is a helpful tool to evaluate patients with foot complaints. In general, average and maximum plantar pressure of 6-11 areas under the foot are used to compare groups of subjects. However,

  9. 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

    1982-01-01

    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 and ...

  10. Using Smartphone Pressure Sensors to Measure Vertical Velocities of Elevators, Stairways, and Drones

    Science.gov (United States)

    Monteiro, Martín; Martí, Arturo C.

    2017-01-01

    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…

  11. [Measurement of external pressure of peroneal nerve tract coming in contact with lithotomy leg holders using pressure distribution measurement system BIG-MAT®].

    Science.gov (United States)

    Mizuno, Ju; Namba, Chikara; Takahashi, Toru

    2014-10-01

    We investigated external pressure on peroneal nerve tract coming in contact with two kinds of leg holders using pressure distribution measurement system BIG- MAT® (Nitta Corp., Osaka) in the lithotomy position Peak contact (active) pressure at the left fibular head region coming in contact with knee-crutch-type leg holder M® (Takara Belmont Corp., Osaka), which supports the left popliteal fossa, was 78.0 ± 26.4 mmHg. On the other hand, peak contact pressure at the left lateral lower leg region coming in contact with boot-support-type leg holder Bel Flex® (Takara Belmont Corp., Osaka), which supports the left lower leg and foot was 26.3±7.9 mmHg. These results suggest that use of knee-crutch-type leg holder is more likely to induce common peroneal nerve palsy at the fibular head region, but use of boot-support-type leg holder dose not easily induce superficial peroneal nerve palsy at the lateral lower leg region, because capillary blood pressure is known to be 32 mmHg. Safer holders for positioning will be developed to prevent nerve palsy based on the analysis of chronological change in external pressure using BIG-MAT® system during anesthesia.

  12. Relevance to Home Blood Pressure Monitoring Protocol of Blood Pressure Measurements Taken Before First- Morning Micturition and in the Afternoon

    Directory of Open Access Journals (Sweden)

    Antonio Eduardo Monteiro de Almeida

    2014-10-01

    Full Text Available Background: The importance of measuring blood pressure before morning micturition and in the afternoon, while working, is yet to be established in relation to the accuracy of home blood pressure monitoring (HBPM. Objective: To compare two HBPM protocols, considering 24-hour ambulatory blood pressure monitoring (wakefulness ABPM as gold-standard and measurements taken before morning micturition (BM and in the afternoon (AM, for the best diagnosis of systemic arterial hypertension (SAH, and their association with prognostic markers. Methods: After undergoing 24-hour wakefulness ABPM, 158 participants (84 women were randomized for 3- or 5-day HBPM. Two variations of the 3-day protocol were considered: with measurements taken before morning micturition and in the afternoon (BM+AM; and with post-morning-micturition and evening measurements (PM+EM. All patients underwent echocardiography (for left ventricular hypertrophy - LVH and urinary albumin measurement (for microalbuminuria - MAU. Result: Kappa statistic for the diagnosis of SAH between wakefulness-ABPM and standard 3-day HBPM, 3-day HBPM (BM+AM and (PM+EM, and 5-day HBPM were 0.660, 0.638, 0.348 and 0.387, respectively. The values of sensitivity of (BM+AM versus (PM+EM were 82.6% × 71%, respectively, and of specificity, 84.8% × 74%, respectively. The positive and negative predictive values were 69.1% × 40% and 92.2% × 91.2%, respectively. The comparisons of intraclass correlations for the diagnosis of LVH and MAU between (BM+AM and (PM+EM were 0.782 × 0.474 and 0.511 × 0.276, respectively. Conclusions: The 3 day-HBPM protocol including measurements taken before morning micturition and during work in the afternoon showed the best agreement with SAH diagnosis and the best association with prognostic markers.

  13. Second-harmonic-generation measurements on ZnSe under high pressure

    CERN Document Server

    Jin Ming Xing; Mukhtar, E; Ding Da Jun

    2002-01-01

    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.

  14. Correlation of Insulin Resistance with Anthropometric Measures and Blood Pressure in Adolescents

    Science.gov (United States)

    de Morais, Polyana Resende Silva; Sousa, Ana Luiza Lima; Jardim, Thiago de Souza Veiga; Nascente, Flávia Miquetichuc Nogueira; Mendonça, Karla Lorena; Povoa, Thaís Inácio Rolim; Carneiro, Carolina de Souza; Ferreira, Vanessa Roriz; de Souza, Weimar Kunz Sebba Barroso; Jardim, Paulo César Brandão Veiga

    2016-01-01

    Background Blood pressure is directly related to body mass index, and individuals with increased waist circumference have higher risk of developing hypertension, insulin resistance, and other metabolic changes, since adolescence. Objective to evaluate the correlation of blood pressure with insulin resistance, waist circumference and body mass index in adolescents. Methods Cross-section study on a representative sample of adolescent students. One group of adolescents with altered blood pressure detected by casual blood pressure and/or home blood pressure monitoring (blood pressure > 90th percentile) and one group of normotensive adolescents were studied. Body mass index, waist circumference were measured, and fasting glucose and plasma insulin levels were determined, using the HOMA-IR index to identify insulin resistance. Results A total of 162 adolescents (35 with normal blood pressure and 127 with altered blood pressure) were studied; 61% (n = 99) of them were boys and the mean age was 14.9 ± 1.62 years. Thirty-eight (23.5%) adolescents had altered HOMA-IR. The group with altered blood pressure had higher values of waist circumference, body mass index and HOMA-IR (pHOMA-IR than boys (pHOMA-IR in the group with altered blood pressure (ρ = 0.394; p HOMA-IR in both groups (ρ = 0.345; p HOMA-IR was as predictor of altered blood pressure (odds ratio - OR = 2.0; p = 0.001). Conclusion There was a significant association of insulin resistance with blood pressure and the impact of insulin resistance on blood pressure since childhood. The correlation and association between markers of cardiovascular diseases was more pronounced in adolescents with altered blood pressure, suggesting that primary prevention strategies for cardiovascular risk factors should be early implemented in childhood and adolescence. PMID:27007222

  15. An optical method for measuring exhaust gas pressure from an internal combustion engine at high speed

    Science.gov (United States)

    Leach, Felix C. P.; Davy, Martin H.; Siskin, Dmitrij; Pechstedt, Ralf; Richardson, David

    2017-12-01

    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. Effect of body temperature on peripheral venous pressure measurements and its agreement with central venous pressure in neurosurgical patients.

    Science.gov (United States)

    Sahin, Altan; Salman, M Alper; Salman, A Ebru; Aypar, Ulka

    2005-04-01

    Previous studies suggest a correlation of central venous pressure (CVP) with peripheral venous pressure (PVP) in different clinical settings. The effect of body temperature on PVP and its agreement with CVP in patients under general anesthesia are investigated in this study. Fifteen American Society of Anesthesiologists I-II patients undergoing elective craniotomy were included in the study. CVP, PVP, and core (Tc) and peripheral (Tp) temperatures were monitored throughout the study. A total of 950 simultaneous measurements of CVP, PVP, Tc, and Tp from 15 subjects were recorded at 5-minute intervals. The measurements were divided into low- and high-Tc and -Tp groups by medians as cutoff points. Bland-Altman assessment for agreement was used for CVP and PVP in all groups. PVP measurements were within range of +/-2 mm Hg of CVP values in 94% of the measurements. Considering all measurements, mean bias was 0.064 mm Hg (95% confidence interval -0.018-0.146). Corrected bias for repeated measurements was 0.173 +/- 3.567 mm Hg (mean +/- SD(corrected)). All of the measurements were within mean +/- 2 SD of bias, which means that PVP and CVP are interchangeable in our setting. As all the measurements were within 1 SD of bias when Tc was > or = 35.8 degrees C, even a better agreement of PVP and CVP was evident. The effect of peripheral hypothermia was not as prominent as core hypothermia. PVP measurement may be a noninvasive alternative for estimating CVP. Body temperature affects the agreement of CVP and PVP, which deteriorates at lower temperatures.

  17. In-Situ Rolling Element Bearing Temperature and/or Pressure Measurement

    National Research Council Canada - National Science Library

    Nickel, David

    1999-01-01

    ... 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...

  18. The Pathway-Flow Relative Permeability of CO2: Measurement by Lowered Pressure Drops

    Science.gov (United States)

    Zhang, Yi; Nishizawa, Osamu; Park, Hyuck; Kiyama, Tamotsu; Lei, Xinglin; Xue, Ziqiu

    2017-10-01

    We introduce a simple method to measure the relative permeability of supercritical CO2 in low-permeability rocks. The method is built on the assumption of the stability of formed CO2 percolation pathway under lowered pressure drops. Initially, a continuous CO2 flow pathway is created under a relatively high-pressure drop. Then, several subsequent steps of lowered pressure drops are performed while monitoring the associated flow rates. When the pressure drop is lower than a threshold value, the created flow pathway is assumed to be adequately stable and does not vary significantly during successive flows, with the average saturation and flow rate achieving a quasi steady state. The relative permeability of CO2 is then calculated from the relationship between the pressure drop and flow rate at several lowered pressure drops according to the extended form of Darcy's law. We demonstrate this method using both numerical modeling and an experimental test using X-ray CT imaging. The results indicate the validity of the assumption for the stability of flow pathway under lowered pressure drops. A linear relationship between the lowered pressure drops and the corresponding CO2 flow rate is found. Furthermore, the measurement results suggest that the relative permeability of CO2 can still be high in low-permeability rocks if the CO2 saturation is higher than the threshold value required to build a flow pathway. The proposed method is important for measuring the pathway-flow relative permeability of nonwetting fluids in low-permeability rocks.

  19. A reference data set for validating vapor pressure measurement techniques: homologous series of polyethylene glycols

    Science.gov (United States)

    Krieger, Ulrich K.; Siegrist, Franziska; Marcolli, Claudia; Emanuelsson, Eva U.; Gøbel, Freya M.; Bilde, Merete; Marsh, Aleksandra; Reid, Jonathan P.; Huisman, Andrew J.; Riipinen, Ilona; Hyttinen, Noora; Myllys, Nanna; Kurtén, Theo; Bannan, Thomas; Percival, Carl J.; Topping, David

    2018-01-01

    To predict atmospheric partitioning of organic compounds between gas and aerosol particle phase based on explicit models for gas phase chemistry, saturation vapor pressures of the compounds need to be estimated. Estimation methods based on functional group contributions require training sets of compounds with well-established saturation vapor pressures. However, vapor pressures of semivolatile and low-volatility organic molecules at atmospheric temperatures reported in the literature often differ by several orders of magnitude between measurement techniques. These discrepancies exceed the stated uncertainty of each technique which is generally reported to be smaller than a factor of 2. At present, there is no general reference technique for measuring saturation vapor pressures of atmospherically relevant compounds with low vapor pressures at atmospheric temperatures. To address this problem, we measured vapor pressures with different techniques over a wide temperature range for intercomparison and to establish a reliable training set. We determined saturation vapor pressures for the homologous series of polyethylene glycols (H - (O - CH2 - CH2)n - OH) for n = 3 to n = 8 ranging in vapor pressure at 298 K from 10-7 to 5×10-2 Pa and compare them with quantum chemistry calculations. Such a homologous series provides a reference set that covers several orders of magnitude in saturation vapor pressure, allowing a critical assessment of the lower limits of detection of vapor pressures for the different techniques as well as permitting the identification of potential sources of systematic error. Also, internal consistency within the series allows outlying data to be rejected more easily. Most of the measured vapor pressures agreed within the stated uncertainty range. Deviations mostly occurred for vapor pressure values approaching the lower detection limit of a technique. The good agreement between the measurement techniques (some of which are sensitive to the mass

  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

    1980-01-01

    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...... of healing correlated significantly with the three distal blood pressure parameters investigated, the closest correlation being with the SDBP measured at the final examination, i.e. just after healing of the ulcer or just before an inevitable major amputation. Of the 22 cases with SDBP below 20 mmHg only two...... and peripheral neuropathy were frequent in the diabetic group. The data show that the systolic digital blood pressure is a particularly valuable prognostic parameter....

  1. Validity of a wrist digital monitor for blood pressure measurement in comparison to a mercury sphygmomanometer.

    Science.gov (United States)

    Menezes, Ana M B; Dumith, Samuel C; Noal, Ricardo B; Nunes, Ana Paula; Mendonça, Fernanda I; Araújo, Cora L P; Duval, Marta A; Caruso, Paulo E; Hallal, Pedro C

    2010-03-01

    Valid measurements of blood pressure, both at clinical and community settings, are essential for monitoring this variable at the population level. To evaluate the validity of a wrist digital monitor for measuring blood pressure among adolescents in comparison to a mercury sphygmomanometer. A validation study was carried out in the city of Pelotas, Southern Brazil. Blood pressure was measured twice using two different sphygmomanometers; an OMRON wrist digital and a desktop BD mercury one. Half of the sample was measured first with the digital manometer and subsequently with the mercury one, whereas the remaining half was evaluated in the opposite order. Agreement between both measures was evaluated using the Bland and Altman method. 120 adolescents aged 14 to 15 years were included (50% of each sex). Mean systolic blood pressure among boys was 113.7 mmHg (SD 14.2) when using the mercury manometer and 115.5 mmHg (SD 15.2) when using the digital one. Equivalent values for diastolic blood pressure were 61.5 mmHg (SD 9.9) and 69.6 mmHg (10.2), respectively. Among girls, the mean systolic blood pressure was 104.7 mmHg (SD 10.1) when using the mercury manometer and 102.4 mmHg (SD 11.9) when using the digital device. Values for diastolic blood pressure were 60.0 mmHg (SD 10.4) and 65.7 mmHg (SD 7.7), respectively. The digital device showed a high level of agreement with the mercury manometer when measuring systolic blood pressure. The level of agreement was lower for diastolic blood pressure. The use of correction equations may be an alternative for studies using this wrist digital monitor in adolescent patients.

  2. Simultaneous Infrared And Pressure Measurements Of Crossflow Instability Modes For HIFiRE 5 (POSTPRINT)

    Science.gov (United States)

    2017-07-01

    Since the shell has a high emissivity and low thermal conductivity, it is also well-suited for infrared (IR) thermography . The use of IR thermography was...AFRL-RQ-WP-TP-2017-0099 SIMULTANEOUS INFRARED AND PRESSURE MEASUREMENTS OF CROSSFLOW INSTABILITY MODES FOR HIFiRE-5 (POSTPRINT) Matthew...Postprint 01 April 2015 – 01 January 2016 4. TITLE AND SUBTITLE SIMULTANEOUS INFRARED AND PRESSURE MEASUREMENTS OF CROSSFLOW INSTABILITY MODES FOR

  3. Thermodynamic properties of the liquid Hg-Tl alloys determined from vapour pressure measurements

    Directory of Open Access Journals (Sweden)

    Gierlotka W.

    2002-01-01

    Full Text Available The partial vapour pressure of mercury over liquid Hg-Tl liquid solutions were determined in the temperature range from 450 to 700 K by direct vapour pressure measurements carried out with the quartz gauge. From the measured ln pHg vs. T relationships activities of mercury were determined. Using Redlich-Kister formulas logarithms of the activity coefficients were described with the following equations: From which all thermodynamic functions in the solutions can be derived.

  4. Measuring and predicting head space pressure during retorting of thermally processed foods.

    Science.gov (United States)

    Ghai, Gaurav; Teixeira, Arthur A; Welt, Bruce A; Goodrich-Schneider, Renee; Yang, Weihua; Almonacid, Sergio

    2011-04-01

    Traditional metal cans and glass jars have been the mainstay in thermally processed canned foods for more than a century, but are now sharing shelf space with increasingly popular flexible pouches and semi-rigid trays. These flexible packages lack the strength of metal cans and glass jars, and need greater control of external retort pressure during processing. Increasing internal package pressure without counter pressure causes volumetric expansion, putting excessive strain on package seals that may lead to serious container deformation and compromised seal integrity. The primary objective of this study was to measure internal pressure build-up within a rigid air-tight container (module) filled with various model food systems undergoing a retort process in which internal product temperature and pressure, along with external retort temperature and pressure, were measured and recorded at the same time. The pressure build-up in the module was compared with the external retort pressure to determine the pressure differential that would cause package distortion in the case of a flexible package system. The secondary objective was to develop mathematical models to predict these pressure profiles in response to known internal temperature and initial and boundary conditions for the case of the very simplest of model food systems (pure water and aqueous saline and sucrose solutions), followed by food systems of increasing compositional complexity (green beans in water and sweet peas in water). Results showed that error between measured and predicted pressures ranged from 2% to 4% for water, saline, and green beans, and 7% to 13% for sucrose solution and sweet peas.   Flexible packages have limited strength, and need more accurate and closer control of retort pressure during processing. The package becomes more flexible as it heats and might expand with increasing internal pressure that may cause serious deformation or rupture if not properly controlled and

  5. Capacitive micromachined ultrasonic transducer for ultra-low pressure measurement: Theoretical study

    Directory of Open Access Journals (Sweden)

    Zhikang Li

    2015-12-01

    Full Text Available Ultra-low pressure measurement is necessary in many areas, such as high-vacuum environment monitoring, process control and biomedical applications. This paper presents a novel approach for ultra-low pressure measurement where capacitive micromachined ultrasonic transducers (CMUTs are used as the sensing elements. The working principle is based on the resonant frequency shift of the membrane under the applied pressure. The membranes of the biased CMUTs can produce a larger resonant frequency shift than the diaphragms with no DC bias in the state-of-the-art resonant pressure sensors, which contributes to pressure sensitivity improvement. The theoretical analysis and finite element method (FEM simulation were employed to study the relationship between the resonant frequency and the pressure. The results demonstrated excellent capability of the CMUTs for ultra-low pressure measurement. It is shown that the resonant frequency of the CMUT varies linearly with the applied pressure. A sensitivity of more than 6.33 ppm/Pa (68 kHz/kPa was obtained within a pressure range of 0 to 100 Pa when the CMUTs were biased at a DC voltage of 90% of the collapse voltage. It was also demonstrated that the pressure sensitivity can be adjusted by the DC bias voltage. In addition, the effects of air damping and ambient temperature on the resonant frequency were also studied. The effect of air damping is negligible for the pressures below 1000 Pa. To eliminate the temperature effect on the resonant frequency, a temperature compensating method was proposed.

  6. Value, Impact, and the Transcendent Library: Progress and Pressures in Performance Measurement and Evaluation

    Science.gov (United States)

    Town, J. Stephen

    2011-01-01

    Libraries are under pressure to prove their worth and may not have achieved this fully successfully. There is a resultant growing requirement for value and impact measurement in academic and research libraries. This essay reviews the natural history of library performance measurement and suggests that proof of worth will be measured by the…

  7. Tutorial and Guidelines on Measurement of Sound Pressure Level in Voice and Speech

    Science.gov (United States)

    Švec, Jan G.; Granqvist, Svante

    2018-01-01

    Purpose: Sound pressure level (SPL) measurement of voice and speech is often considered a trivial matter, but the measured levels are often reported incorrectly or incompletely, making them difficult to compare among various studies. This article aims at explaining the fundamental principles behind these measurements and providing guidelines to…

  8. Reliability of intraocular pressure measurement with the Goldmann applanation tonometer in epidemiological studies

    NARCIS (Netherlands)

    I. Dielemans (Ida); J.R. Vingerling (Hans); A. Hofman (Albert); D.E. Grobbee (Diederick); P.T.V.M. de Jong (Paulus)

    1994-01-01

    textabstractThe reproducibility of intraocular pressure (IOP) measurement with the Goldmann applanation tonometer was investigated as part of a population-based epidemiological study. Sixty-two subjects were examined in a first measurement session. The IOP was measured three times consecutively in

  9. In vitro measurement of ambient pressure changes using a realistic clinical setup

    DEFF Research Database (Denmark)

    Andersen, Klaus Scheldrup; Jensen, Jørgen Arendt

    2008-01-01

    In vitro measurement of ambient pressure changes using a realistic clinical setup Klaus Scheldrup Andersen and Jørgen Arendt Jensen Motivation and objective: Many attempts to find a non-invasive procedure to measure the local blood pressure have been made. In the last decade independent experiments...... cosine tapered pulse with a center frequency of 4 MHz and an acoustic pressure of 485 kPa was used for excitation. 64 elements were used in receive and the RF data was filtered and beamformed before further processing. To compensate for variations in bubble response and to make the estimates more robust...

  10. Laser Induced Fluorescence Measurements in a Hall Thruster Plume as a Function of Background Pressure

    Science.gov (United States)

    Spektor, R.; Tighe, W. G.; Kamhawi, H.

    2016-01-01

    A set of Laser Induced Fluorescence (LIF) measurements in the near-field region of the NASA- 173M Hall thruster plume is presented at four background pressure conditions varying from 9.4 x 10(exp -6) torr to 3.3 x 10(exp -5) torr. The xenon ion velocity distribution function was measured simultaneously along the axial and radial directions. An ultimate exhaust velocity of 19.6+/-0.25 km/s achieved at a distance of 20 mm was measured, and that value was not sensitive to pressure. On the other hand, the ion axial velocity at the thruster exit was strongly influenced by pressure, indicating that the accelerating electric field moved inward with increased pressure. The shift in electric field corresponded to an increase in measured thrust. Pressure had a minor effect on the radial component of ion velocity, mainly affecting ions exiting close to the channel inner wall. At that radial location the radial component of ion velocity was approximately 1000 m/s greater at the lowest pressure than at the highest pressure. A reduction of the inner magnet coil current by 0.6 A resulted in a lower axial ion velocity at the channel exit while the radial component of ion velocity at the channel inner wall location increased by 1300 m/s, and at the channel outer wall location the radial ion velocity remained unaffected. The ultimate exhaust velocity was not significantly affected by the inner magnet current.

  11. Dynamic calibration of piezoelectric transducers for ballistic high-pressure measurement

    Directory of Open Access Journals (Sweden)

    Elkarous Lamine

    2016-01-01

    Full Text Available The development of a dynamic calibration standard for high-amplitude pressure piezoelectric transducers implies the implementation of a system which can provide reference pressure values with known characteristics and uncertainty. The reference pressure must be issued by a sensor, as a part of a measuring chain, with a guaranteed traceability to an international standard. However, this operation has not been completely addressed yet until today and is still calling further investigations. In this paper, we introduce an experimental study carried out in order to contribute to current efforts for the establishment of a reference dynamic calibration method. A suitable practical calibration method based on the calculation of the reference pressure by measurement of the displacement of the piston in contact with an oil-filled cylindrical chamber is presented. This measurement was achieved thanks to a high speed camera and an accelerometer. Both measurements are then compared. In the first way, pressure was generated by impacting the piston with a free falling weight and, in the second way, with strikers of known weights and accelerated to the impact velocities with an air gun. The aim of the experimental setup is to work out a system which may generate known hydraulic pressure pulses with high-accuracy and known uncertainty. Moreover, physical models were also introduced to consolidate the experimental study. The change of striker’s velocities and masses allows tuning the reference pressure pulses with different shapes and, therefore, permits to sweep a wide range of magnitudes and frequencies.

  12. Airborne and ground based lidar measurements of the atmospheric pressure profile

    Science.gov (United States)

    Korb, C. Laurence; Schwemmer, Geary K.; Dombrowski, Mark; Weng, Chi Y.

    1989-01-01

    The first high accuracy remote measurements of the atmospheric pressure profile have been made. The measurements were made with a differential absorption lidar system that utilizes tunable alexandrite lasers. The absorption in the trough between two lines in the oxygen A-band near 760 nm was used for probing the atmosphere. Measurements of the two-dimensional structure of the pressure field were made in the troposphere from an aircraft looking down. Also, measurements of the one-dimensional structure were made from the ground looking up. Typical pressure accuracies for the aircraft measurements were 1.5-2 mbar with a 30-m vertical resolution and a 100-shot average (20 s), which corresponds to a 2-km horizontal resolution. Typical accuracies for the upward viewing ground based measurements were 2.0 mbar for a 30-m resolution and a 100-shot average.

  13. Diagnostic accuracy of intraocular pressure measurement for the detection of raised intracranial pressure: meta-analysis: a systematic review.

    Science.gov (United States)

    Yavin, Daniel; Luu, Judy; James, Matthew T; Roberts, Derek J; Sutherland, Garnette R; Jette, Nathalie; Wiebe, Samuel

    2014-09-01

    Because clinical examination and imaging may be unreliable indicators of intracranial hypertension, intraocular pressure (IOP) measurement has been proposed as a noninvasive method of diagnosis. The authors conducted a systematic review and meta-analysis to determine the correlation between IOP and intracranial pressure (ICP) and the diagnostic accuracy of IOP measurement for detection of intracranial hypertension. The authors searched bibliographic databases (Ovid MEDLINE, Ovid EMBASE, and the Cochrane Central Register of Controlled Trials) from 1950 to March 2013, references of included studies, and conference abstracts for studies comparing IOP and invasive ICP measurement. Two independent reviewers screened abstracts, reviewed full-text articles, and extracted data. Correlation coefficients, sensitivity, specificity, and positive and negative likelihood ratios were calculated using DerSimonian and Laird methods and bivariate random effects models. The I(2) statistic was used as a measure of heterogeneity. Among 355 identified citations, 12 studies that enrolled 546 patients were included in the meta-analysis. The pooled correlation coefficient between IOP and ICP was 0.44 (95% CI 0.26-0.63, I(2) = 97.7%, p intracranial hypertension were 81% (95% CI 26%-98%, I(2) = 95.2%, p intracranial hypertension. Given the significant heterogeneity between included studies, further investigation is required prior to the adoption of IOP in the evaluation of intracranial hypertension into routine practice.

  14. Measurements of blood pressure with various techniques in daily practice: uncertainty in diagnosing office hypertension with short-term in-hospital registration of blood pressure

    NARCIS (Netherlands)

    Braun, H. J.; Rabouw, H.; Werner, H.; van Montfrans, G. A.; de Stigter, C.; Zwinderman, A. H.

    1999-01-01

    To predict blood pressure outside the clinic from a short-term in-hospital registration for patients referred for ambulatory blood pressure monitoring (ABPM) with special attention to office hypertension. A series of measurements of blood pressure was performed by the same technician for 187

  15. Relationship between intracranial pressure and phase contrast cine MRI derived measures of intracranial pulsations in idiopathic normal pressure hydrocephalus.

    Science.gov (United States)

    Jaeger, Matthias; Khoo, Angela K; Conforti, David A; Cuganesan, Ramesh

    2016-11-01

    Phase contrast cine MRI with determination of pulsatile aqueductal cerebrospinal fluid (CSF) stroke volume and flow velocity has been suggested to assess intracranial pulsations in idiopathic normal pressure hydrocephalus (iNPH). We aimed to compare this non-invasive measure of pulsations to intracranial pressure (ICP) pulse wave amplitude from continuous ICP monitoring. We hypothesised that a significant correlation between these two markers of intracranial pulsations exists. Fifteen patients with suspected iNPH had continuous computerised ICP monitoring with calculation of mean ICP pulse wave amplitude (MWA) from time-domain analysis. MRI measured CSF aqueductal stroke volume and peak flow velocity. Mean MWA was 5.4mmHg (range 2.3-12.4mmHg). Mean CSF stroke volume and peak flow velocity were 65μl (range 3-195μl) and 9.31cm/s (range 1.68-15.0cm/s), respectively. No significant correlation between the invasive and non-invasive measures of pulsations existed (Spearman r=-0.30 and r=-0.27, respectively; p>0.05). We observed marked intra-individual fluctuation of MWA during continuous ICP monitoring of an average of 6.0mmHg (range 2.8-12.2mmHg). The results suggest a complex interplay between measures of pulsations derived from snapshot MRI measurements and continuous computerised ICP measurements, as no significant relationship existed in our data. Further study is needed to better understand the temporal profile of CSF MRI flow studies, as substantial variation in MWA over the course of several hours of ICP monitoring is common, suggesting that these physiologic fluctuations might obscure MRI snapshot measures of intracranial pulsations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. 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

    1980-01-01

    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...... (SPPH) as measured with a photocell. Thirty-two patients (35 feet with ulcerations) had diabetes mellitus. The treatment was conservative. In 42 feet the ulcers healed after an average period of 5.8 months; in 24 feet major amputation became necessary after an average of 4.3 months. The frequency...... of healing correlated significantly with the three distal blood pressure parameters investigated, the closest correlation being with the SDBP measured at the final examination, i.e. just after healing of the ulcer or just before an inevitable major amputation. Of the 22 cases with SDBP below 20 mmHg only two...

  17. Development of the CARS method for measurement of pressure and temperature gradients in centrifuges

    International Nuclear Information System (INIS)

    Zeltmann, A.H.; Valentini, J.J.

    1983-12-01

    These experiments evaluated the feasibility of applying the CARS technique to the measurement of UF 6 concentrations and pressure gradients in a gas centrifuge. The resultant CARS signals were properly related to system parameters as suggested by theory. The results have been used to guide design of an apparatus for making CARS measurements in a UF 6 gas centrifuge. Ease of measurement is expected for pressures as low as 0.1 torr. Temperature gradients can be measured by this technique with changes in the data acquisition method. 16 references, 8 figures, 2 tables

  18. Laser-Machined Microcavities for Simultaneous Measurement of High-Temperature and High-Pressure

    Directory of Open Access Journals (Sweden)

    Zengling Ran

    2014-08-01

    Full Text Available Laser-machined microcavities for simultaneous measurement of high-temperature and high-pressure are demonstrated. These two cascaded microcavities are an air cavity and a composite cavity including a section of fiber and an air cavity. They are both placed into a pressure chamber inside a furnace to perform simultaneous pressure and high-temperature tests. The thermal and pressure coefficients of the short air cavity are ~0.0779 nm/°C and ~1.14 nm/MPa, respectively. The thermal and pressure coefficients of the composite cavity are ~32.3 nm/°C and ~24.4 nm/MPa, respectively. The sensor could be used to separate temperature and pressure due to their different thermal and pressure coefficients. The excellent feature of such a sensor head is that it can withstand high temperatures of up to 400 °C and achieve precise measurement of high-pressure under high temperature conditions.

  19. Absolute measurement of the Hugoniot and sound velocity of liquid copper at multimegabar pressures

    Science.gov (United States)

    McCoy, Chad A.; Knudson, Marcus D.; Root, Seth

    2017-11-01

    Measurement of the Hugoniot and sound velocity provides information on the bulk modulus and Grüneisen parameter of a material at extreme conditions. The capability to launch multilayered (copper/aluminum) flyer plates at velocities in excess of 20 km/s with the Sandia Z accelerator has enabled high-precision sound-velocity measurements at previously inaccessible pressures. For these experiments, the sound velocity of the copper flyer must be accurately known in the multi-Mbar regime. Here we describe the development of copper as an absolutely calibrated sound-velocity standard for high-precision measurements at pressures in excess of 400 GPa. Using multilayered flyer plates, we performed absolute measurements of the Hugoniot and sound velocity of copper for pressures from 500 to 1200 GPa. These measurements enabled the determination of the Grüneisen parameter for dense liquid copper, clearly showing a density dependence above the melt transition. Combined with earlier data at lower pressures, these results constrain the sound velocity as a function of pressure, enabling the use of copper as a Hugoniot and sound-velocity standard for pressures up to 1200 GPa.

  20. Intradiscal O2O3: Rationale, Injection Technique, Short- and Long-term Outcomes for the Treatment of Low Back Pain Due to Disc Herniation.

    Science.gov (United States)

    Giurazza, Francesco; Guarnieri, Gianluigi; Murphy, Kieran J; Muto, Mario

    2017-05-01

    The management of low back pain should always start with a conservative approach; however, when it fails, intervention is required and at that moment the most appropriate choice remains unclear. Before invasive surgery, minimally invasive techniques can be adopted. In European trials and in a trans-Canadian clinical trial 03 ozone has been used successfully. In total over 50,000 patients have been treated safely. Ozone is a gas normally present in the atmosphere with potent oxidizing power; it has been used for percutaneous intradiscal injection combined with oxygen (O 2 O 3 ) at very low concentrations for 15 years in Europe. The main indication is back pain with or without radicular pain but without motor deficits, which is refractory to 4-6 weeks of conservative therapies. Its mechanism of action on the disc is mechanical (volume reduction by subtle dehydration of the nucleus pulposis) and antinflammatory. The intradiscal ozone injection is performed with a thin needle (18-22 gauge) image guided by computed tomography or angiofluoroscopy and is usually complimented by periganglionic injection of corticosteroids and anesthetics. This combination gives immediate pain relief and allows time for the ozone to act. It is a cost-effective procedure that presents a very low complication rate (0.1%). The radicular pain is resolved before the back pain does, as is seen with microdiscectomy. Peer-reviewed publications of large randomized trials, case series, and meta analysis from large samples of patients have demonstrated the procedure to be safe and effective in the short and the long terms, with benefits recognized up to 10 years after treatment. We aim to review the principles of action of O 2 O 3 and report the injection techniques, complications, and short- and long-term outcomes. Copyright © 2017 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.

  1. Adjusting adiposity and body weight measurements for height alters the relationship with blood pressure in children

    Science.gov (United States)

    Willig, Amanda L.; Casazza, Krista; Dulin-Keita, Akilah; Franklin, Frank A.; Amaya, Michelle; Fernandez, Jose R.

    2010-01-01

    BACKGROUND Adiposity measures are associated with increased pediatric blood pressure. However, this correlation can be confounded by the relationship of both variables to height. We evaluated whether adiposity and anthropometric measures were associated with pediatric blood pressure before and after adjusting each value for height. METHODS Participants included 281 African-American, European-American, and Hispanic-American children aged 7–12 years. Blood pressure percentiles were calculated according to pediatric guidelines using the average of four measurements. Total fat mass was determined using dual-energy x-ray absorptiometry. Socioeconomic status was calculated with the Hollingshead index. Adiposity measures were indexed for height using log-log regression analysis. Partial correlations identified measures associated with blood pressure. Linear regression was used to test the association of those measures with absolute blood pressure, while logistic regression was used to evaluate the odds for hypertension. RESULTS More African-Americans (16.3%) presented with potential hypertension than European-American (5.1%) or Hispanic-American (2.7%) children. After adjusting for covariates, fat mass, body mass index, and waist circumference were positively significantly associated with absolute blood pressure and hypertension in African-American and European-American children (P < 0.05). When these measures were height-indexed, only waist remained significantly positively associated with hypertension risk in these two groups. No measures were significantly associated with blood pressure among Hispanic-American children. CONCLUSIONS In this multiethnic pediatric population, waist circumference was the strongest significant adiposity predictor of hypertension risk among African-American and European-American children. Additional research is needed to determine which environmental and genetic factors contribute to pediatric hypertension, particularly among Hispanic

  2. A method to measure paddle and detector pressures and footprints in mammography

    International Nuclear Information System (INIS)

    Hogg, Peter; Szczepura, Katy; Darlington, Alison; Maxwell, Anthony

    2013-01-01

    Purpose: Compression is necessary in mammography to improve image quality and reduce radiation burden. Maximizing the amount of breast in contact with the image receptor (IR) is important. To achieve this, for the craniocaudal projection, there is no consensus within the literature regarding how the IR should be positioned relative to the inframammary fold (IMF). No information exists within the literature to describe how pressure balancing between IR and paddle, and IR breast footprint, might be optimized. This paper describes a novel method for measuring the respective pressures applied to the breast from the IR and the paddle and a method to simultaneously measure the breast footprints on the IR and the paddle. Methods: Using a deformable breast phantom and electronic pressure-sensitive mat, area and pressure readings were gathered from two mammography machines and four paddles at 60, 80, and 100 N with the IR positioned at −2, −1, 0, +1, and +2 cm relative to the IMF (60 combinations in total). Results: Paddle and IR footprints were calculated along with a uniformity index (UI). For all four paddle/machine/pressure combinations the greatest IR footprint was achieved at IMF +2 cm. The UI indicates that the best pressure/footprint balance is achieved at IMF +1 cm. Conclusions: The authors’ method appears to be suited to measuring breast footprints and pressures on IR and paddle and a human female study is planned.

  3. Assessment on shock pressure acquisition from underwater explosion using uncertainty of measurement

    Directory of Open Access Journals (Sweden)

    Seok-Jun Moon

    2017-11-01

    Full Text Available This study aims to verify experimentally the specifications of the data acquisition system required for the precise measurement of signals in an underwater explosion (UNDEX experiment. The three data acquisition systems with different specifications are applied to compare their precision relatively on maximum shock pressures from UNDEX. In addition, a method of assessing the acquired signals is suggested by introducing the concept of measurement uncertainty. The underwater explosion experiments are repeated five times under same conditions, and assessment is conducted on maximum quantities acquired from underwater pressure sensors. It is confirmed that the concept of measurement uncertainty is very useful method in accrediting the measurement results of UNDEX experiments. Keywords: Naval ship, Underwater explosion (UNDEX experiment, Shock pressure, Data acquisition system, Uncertainty of measurement

  4. Simultaneous measurement of arterial and left ventricular pressure in conscious freely moving rats by telemetry.

    Science.gov (United States)

    Segreti, Jason A; Polakowski, James S; Blomme, Eric A; King, Andrew J

    2016-01-01

    Comprehensive cardiovascular assessment in conscious rodents by utilizing telemetry has been limited by the restriction of current devices to one pressure channel. The purpose of this study was to test and validate a dual pressure transmitter that allows the simultaneous measurement of arterial pressure (AP) and left ventricular pressure (LVP) in conscious freely moving rats. Six rats were surgically implanted with dual pressure transmitters. Baseline hemodynamics and circadian rhythm were observed to return within 7days. AP, heart rate (HR), LVP and indices of left ventricular contractility were stable and demonstrated a prominent circadian rhythm over a two-week period of uninterrupted recordings. Administration of the vasodilator nifedipine produced the anticipated dose-dependent decrease in AP which was accompanied by a baroreflex mediated increase in HR and cardiac contractility. The negative inotrope verapamil produced the expected dose-dependent decreases in AP and cardiac contractility. Finally, a terminal validation of the dual pressure transmitter was performed under anesthesia by measuring AP and LVP simultaneously via telemetry and from a fluid filled arterial catheter and an intraventricular Millar catheter, respectively. A range of pressures and cardiac contractility were studied by administering sequential intravenous infusions of the positive inotrope dobutamine followed by verapamil. Linear regression analysis revealed a high level of agreement between pressures measured by the dual pressure transmitter and the exteriorized catheters. Histopathologic analysis of the heart revealed mild peri-catheter fibrosis. In conclusion, the simultaneous measurement of AP and LVP offers the potential for more detailed cardiovascular assessment in conscious rats. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. MEASUREMENTS OF PRESSURE DISTRIBUTIONS ON A ROTOR BLADE USING PSP TECHNIQUES

    Directory of Open Access Journals (Sweden)

    Kidong Kim

    2011-12-01

    Full Text Available Surface pressure distributions on a rotating blade were measured by using pressure sensitive paint (PSP to understand aerodynamic characteristics of a rotor blade. The present study was conducted to investigate the PSP techniques for measuring the pressure distributions on a rotor blade. In order to perform the experiment, the PSP was required to response very fast due to rapid pressure fluctuations on a rotor blade. High energy excitation light source was also needed to acquire proper intensity images in a short excitation time. The techniques were based on a lifetime method. Qualitative pressure distributions on an upper surface of small scale rotor in hovering condition were measured as a preliminary experiment prior to forward flight conditions in the KARI low speed wind tunnel laboratory. From measured pressure distributions, striking pressure gradient was observed on an upper surface of rotor blade and the resulting pressure showed expected gradient depending on different collective pitch angles. ABSTRAK : Pengagihan tekanan permukaan ke atas berbilah putar disukat menggunakan cat sensitive tekanan (pressure sensitive paint (PSP untuk memahami sifat-sifat aerodinamik suatu berbilah putar. Kajian telah dijalankan untuk menyelidik teknik-teknik PSP dengan mengukur agihan tekanan ke atas suatu berbilah putar. Agar eksperimen dapat dijalankan dengan baik, PSP harus bertindak cepat kerana tekanan naik turun dengan pantas ke atas berbilah putar. Sumber cahaya ujaan tenaga tinggi diperlukan untuk mendapatkan imej keamatan wajar dalam jangka masa ujaan yang pendek. Teknik-teknik tersebut terhasil daripada kajian semasa hayat. Agihan tekanan kualitatif ke permukaan atas berskala kecil pemutar dalam keadaan mengapung diukur sebagai permulaan eksperimen, sebelum penerbangan kehadapan dalam makmal terowong angin laju rendah KARI. Daripada agihan tekanan yang disukat, kecerunan tekanan yang ketara diperolehi daripada permerhatian terhadap permukaan

  6. Measurements of peripherical static pressure and pressure drop in a rod bundle with helical wire wrap spacers

    International Nuclear Information System (INIS)

    Ballve, H.; Graca, M.C.; Fernandez y Fernandez, E.; Carajilescov, P.

    1981-07-01

    The fuel element of a LMFBR nuclear reactor consists of a wire wrapped rod bundle with triangular array with the coolant flowing parallel to the rods. Using this type of element with seven rods conected to an air open loop. The hydrodinamics behavior of the flow for p/d = 1.20 and l/d = 15.0, was simulated. Several measurements were performed in order to obtain the static pressure distribution at the walls of the hexagonal duct, for Reynolds number from 4.4x10 3 to 48.49x10 3 and for different axial and transverse positions, in a wire wrap lead. The axial pressure drop was obtained and determined the friction factor dependence with the Reynolds number. From the obtained results, it was observed the non-dependency of the non-dimensionalized axial and transverse local static pressure distribution at the wall of the hexagonal duct, with the Reynolds number. The obtained friction factor is compared to the results of previous works. (Author) [pt

  7. In the aftermath of SPRINT: further comparison of unattended automated office blood pressure measurement and 24-hour blood pressure monitoring.

    Science.gov (United States)

    Seidlerová, Jitka; Gelžinský, Julius; Mateřánková, Markéta; Ceral, Jiří; König, Petr; Filipovský, Jan

    2018-03-22

    Several papers reported that unattended automated office blood pressure (uAutoOBP) is closely related to daytime ambulatory blood pressure monitoring (ABPM). In the present study, we aim to study uAutoOBP and its relation to 24-hour ABPM and ABPM variability. Stable treated hypertensive subjects were examined in two Czech academic hypertension centres. uAutoOBP was measured with the BP Tru device; attended BP three times with auscultatory method (AuscOBP) by the physician. ABPM was performed within one week from the clinical visit. Data on 98 subjects aged 67.7 ± 9.3 years with 24-hour ABPM 120.3 ± 10.6/72.7 ± 7.9 mm Hg are reported. uAutoOBP was lower than 24-hour (by -5.2 ± 11.3/-0.5 ± 6.9 mm Hg) and daytime (by -6.7 ± 12.82.4 ± 8.0 mm Hg) ABPM and the individual variability of the difference was very large (up to 30 mm Hg). The correlation coefficients between ABPM and uAutoOBP were similar compared to AuscOBP (p ≥ .17). Variability of uAutoOBP, but not AuscOBP, readings during one clinical visit was related to short-term blood pressure variability of ABPM. The difference between AuscOBP and uAutoOBP was larger in patients with white-coat effect compared to other blood pressure control groups (25.1 ± 7.0 vs. 2.2 ± 10.3 mm Hg; p = .0036). Our study shows that uAutoOBP is not good predictor of ambulatory blood pressure monitoring, not even of the daytime values. It might, however, indicate short-term blood pressure variability and, when compared with AuscOBP, also detect patients with white-coat effect.

  8. Review on recent research progress on laser power measurement based on light pressure

    Science.gov (United States)

    Lai, WenChang; Zhou, Pu

    2018-03-01

    Accurate measuring the laser power is one of the most important issue to evaluate the performance of high power laser. For the time being, most of the demonstrated technique could be attributed to direct measuring route. Indirect measuring laser power based on light pressure, which has been under intensive investigation, has the advantages such as fast response, real-time measuring and high accuracy, compared with direct measuring route. In this paper, we will review several non-traditional methods based on light pressure to precisely measure the laser power proposed recently. The system setup, measuring principle and scaling methods would be introduced and analyzed in detail. We also compare the benefit and the drawback of these methods and analyze the uncertainties of the measurements.

  9. Effect of ultrasonic cavitation on measurement of sound pressure using hydrophone

    Science.gov (United States)

    Thanh Nguyen, Tam; Asakura, Yoshiyuki; Okada, Nagaya; Koda, Shinobu; Yasuda, Keiji

    2017-07-01

    Effect of ultrasonic cavitation on sound pressure at the fundamental, second harmonic, and first ultraharmonic frequencies was investigated from low to high ultrasonic intensities. The driving frequencies were 22, 304, and 488 kHz. Sound pressure was measured using a needle-type hydrophone and ultrasonic cavitation was estimated from the broadband integrated pressure (BIP). With increasing square root of electric power applied to a transducer, the sound pressure at the fundamental frequency linearly increased initially, dropped at approximately the electric power of cavitation inception, and afterward increased again. The sound pressure at the second harmonic frequency was detected just below the electric power of cavitation inception. The first ultraharmonic component appeared at around the electric power of cavitation inception at 304 and 488 kHz. However, at 22 kHz, the first ultraharmonic component appeared at a higher electric power than that of cavitation inception.

  10. Prognostic significance of distal blood pressure measurements in patients with severe ischaemia

    DEFF Research Database (Denmark)

    Paaske, William; Tønnesen, K H

    1980-01-01

    The clinical course was followed and the ankle and toe blood pressures were measured with the strain gauge technique on 5 occasions during 2 years in 43 patients with pain at rest and/or ischaemic ulceration due to severe ischaemia of the legs on the basis of occlusive arterial disease. Although...... arteriosclerosis of the legs in non-diabetic patients is generally considered a benign disease from the standpoint of limb survival, the critical level of TPI (systolic toe blood pressure/systolic arm blood pressure) was found to be 0.07 as a TPI below this value was associated with an overall 82% risk...... of amputation. With TPI above 0.07, the chance of successful conservative therapy was about 40%. Diabetics with severe ischaemia must be regarded as a high risk group in respect of amputation (64%) and lethality (64%). A variance analysis was made on the pressure data: In patients with low pressure peripheral...

  11. Synchronous Surface Pressure and Velocity Measurements of standard model in hypersonic flow

    Directory of Open Access Journals (Sweden)

    Zhijun Sun

    2018-01-01

    Full Text Available Experiments in the Hypersonic Wind tunnel of NUAA(NHW present synchronous measurements of bow shockwave and surface pressure of a standard blunt rotary model (AGARD HB-2, which was carried out in order to measure the Mach-5-flow above a blunt body by PIV (Particle Image Velocimetry as well as unsteady pressure around the rotary body. Titanium dioxide (Al2O3 Nano particles were seeded into the flow by a tailor-made container. With meticulous care designed optical path, the laser was guided into the vacuum experimental section. The transient pressure was obtained around model by using fast-responding pressure-sensitive paint (PSPsprayed on the model. All the experimental facilities were controlled by Series Pulse Generator to ensure that the data was time related. The PIV measurements of velocities in front of the detached bow shock agreed very well with the calculated value, with less than 3% difference compared to Pitot-pressure recordings. The velocity gradient contour described in accord with the detached bow shock that showed on schlieren. The PSP results presented good agreement with the reference data from previous studies. Our work involving studies of synchronous shock-wave and pressure measurements proved to be encouraging.

  12. DAC Measurement of High-Pressure Yield Strength of Vanadium using In-Situ Thickness Determination

    Energy Technology Data Exchange (ETDEWEB)

    Klepeis, J P; Cynn, H; Evans, W J; Rudd, R E; Yang, L H; Liermann, H P; Yang, W

    2009-07-16

    The pressure-dependence of the quasi-static yield strength of vanadium in polycrystalline foils and powders has been measured up to 80 GPa at room temperature using an implementation of a non-hydrostatic diamond anvil cell technique [C. Meade and R. Jeanloz, J. Geophys. Res. 93, 3261 (1988)]. A new feature of this work is the use of an in-situ determination of the sample thickness. Following an initial increase in the strength with pressure, a decrease in the strength of vanadium was observed beginning at 40-50 GPa. We have measured the yield strength of vanadium up to 80 GPa under nonhydrostatic conditions. In this study, we used x-ray diffraction and absorption techniques to make in-situ measurements of the pressure gradient and the sample thickness. These measurements were used to evaluate the pressure-dependence of the material strength. We observed a decease in the yield strength of vanadium over the pressure range of 40-50 GPa. We propose that this change in the yieldstrength pressure-dependence is an indicator of the phase transition from bcc to rhombohedral.

  13. A Newly Designed Fiber-Optic Based Earth Pressure Transducer with Adjustable Measurement Range

    Directory of Open Access Journals (Sweden)

    Hou-Zhen Wei

    2018-03-01

    Full Text Available A novel fiber-optic based earth pressure sensor (FPS with an adjustable measurement range and high sensitivity is developed to measure earth pressures for civil infrastructures. The new FPS combines a cantilever beam with fiber Bragg grating (FBG sensors and a flexible membrane. Compared with a traditional pressure transducer with a dual diaphragm design, the proposed FPS has a larger measurement range and shows high accuracy. The working principles, parameter design, fabrication methods, and laboratory calibration tests are explained in this paper. A theoretical solution is derived to obtain the relationship between the applied pressure and strain of the FBG sensors. In addition, a finite element model is established to analyze the mechanical behavior of the membrane and the cantilever beam and thereby obtain optimal parameters. The cantilever beam is 40 mm long, 15 mm wide, and 1 mm thick. The whole FPS has a diameter of 100 mm and a thickness of 30 mm. The sensitivity of the FPS is 0.104 kPa/με. In addition, automatic temperature compensation can be achieved. The FPS’s sensitivity, physical properties, and response to applied pressure are extensively examined through modeling and experiments. The results show that the proposed FPS has numerous potential applications in soil pressure measurement.

  14. Measurements of endotracheal tube cuff contact pressure using fibre Bragg gratings

    Science.gov (United States)

    Hernandez, F. U.; Correia, R.; Korposh, S.; Morgan, S. P.; Hayes-Gill, B. R.; James, S. W.; Evans, D.; Norris, A.

    2015-09-01

    An optical fibre Bragg grating (FBG) was used to measure local strain (due to contact pressure) at the interface of a cuffed endotracheal tube (ETT) tested in a tracheal model. The tracheal model consisted of a corrugated tube. Two FBG sensors written in a single optical fibre were attached to the outside wall of the cuff of the ETT. Intracuff endotracheal pressure was measured using a digital manometer, while the contact pressure between the model trachea and the ETT was measured using Flexiforce sensors. Changes in the Bragg wavelengths in response to the inflation of the cuff of the ETT, and concomitant pressure increase, were observed to be dependent on the location of the FBGs at the corrugations, i.e., the annular peaks and troughs of the corrugated tube. The performance of both contact pressure sensors FBG and Flexiforce suggests that FBG technology is better suited to this application as it allows the measurement of contact pressures on non-uniform surfaces such as in the tracheal model.

  15. The calibration of a cylindrical pressure probe for recirculating flow measurements

    International Nuclear Information System (INIS)

    Lawn, C.J.

    1975-06-01

    The use of the pressure distribution around a cylinder in cross-flow to indicate the magnitude and direction of the velocity vector is discussed in the context of making measurements in highly turbulent recirculating flows. The intended application is the measurement of the flow between the ribs on the large-scale model of the AGR fuel-pin surface. Results from a number of calibration experiments in boundary layers are used to provide a correlation for the positions at which local static pressure is measured on the cylinder surface. After appropriate corrections, the dynamic pressure is deduced from the pressure at the stagnation point. Corrections are also necessary in deducing the direction of flow from the bisector of the static pressure positions, when the cylinder is in a shear flow or near a wall, and these too are evaluated from the results of the calibration experiments. Measurements in two recirculating flows are then presented as an illustration both of the validity and limitations of the technique. In the first case, comparison is made with the measurements of a pulsed-wire anemometer behind a surface-mounted cube and, in the second, the continuity is used to provide an overall check on measurements behind a transverse plate. It is concluded that useful results can be obtained in many turbulent flow situations. (author)

  16. [Practices and effects of different measures for blood pressure control in hypertension patients in Beijing, 2014].

    Science.gov (United States)

    Li, H; Dong, Z; Ma, A J; Dong, J; Fang, K; Xie, C; Qi, K; Xie, J; Zhou, Y; Zhao, Y

    2016-09-10

    Objective: To understand the practices and effects of different measures for blood pressure control in hypertension patients. Methods: Patients who have known hypertension from the subjects of "2014 Beijing adult (aged 18-79 years) chronic diseases and risk factors survey" were selected. The choices of different hypertension control measures, the relationship between the measures and demographic characteristics of hypertension patients, and the effects of different control measures were analyzed. Results: A total of 2 229 known hypertension patients were included, the analysis was conducted through a questionnaire survey. Those who answered "never taking any measures" , "taking medication according to doctor's instructions" and "taking medication when blood pressure rose" accounted for 7.0%, 79.8% and 8.3%, respectively. Those who had "diet control" , "physical exercises" and "blood pressure monitoring" accounted for 22.4%, 23.7% and 22.1%, respectively. In terms of "taking medicine according to doctor's instructions" , women (84.3%), those aged ≥60 years (87.6%), those living in urban area (81.5%), those living alone (83.8%), and Beijing local residents (82.3%) had higher compliance rates. As for "diet control" , women (24.4%), those aged ≥60 years (25.8%) and those with educational level of college or above (29.5%) had better practices. In terms of "physical exercise" , those aged ≥60 years (27.9%), those living in urban area (25.3%), those with educational level of college or above (32.5%) had better practice. Women (24.2%) and those aged ≥60 years (28.4%) had higher "blood pressure monitoring" rate. More men (9.7%), those aged 18-44 years (14.7%), those with educational level of high school (9.3%), the unmarried (18.2%), and non-Beijing local residents (14.7%) answered "never taking any measure" , and in terms of "taking medication when blood pressure rose" , non-Beijing local residents (12.8%) had higher rate. In the field survey, more patients who

  17. Single-phase pressure-drop measurements over low void reactivity fuel

    International Nuclear Information System (INIS)

    Senaratne, U.P.M.; Leung, L.K.H.; Doria, F.J.; Lau, J.H.

    2006-01-01

    An experiment has been performed to obtain pressure-drop measurements over Low Reactivity Fuel (LVRF) bundles in Refrigerant-134a flow. Production LVRF bundles inserted into the test station with either an uncrept or a 5.1% crept flow channel. For comparison purposes, several production Bruce 37-element bundles were also included in the test string. Overall, the single-phase pressure drop of the LVRF bundle is slightly higher than that Bruce 37-element bundle. Pressure-drop measurements were used to derive bundle and loss coefficients for hydraulic calculations in safety analyses. Applying these loss coefficients, an assessment showed that the overall pressure drop over a string of 12 LVRF bundles (after conversion) remains less than that over a string of 13 Bruce 37-element fuel bundles (before conversion) at the Bruce Nuclear Generating Station. (author)

  18. [The research in a foot pressure measuring system based on LabVIEW].

    Science.gov (United States)

    Li, Wei; Qiu, Hong; Xu, Jiang; He, Jiping

    2011-01-01

    This paper presents a system of foot pressure measuring system based on LabVIEW. The designs of hardware and software system are figured out. LabVIEW is used to design the application interface for displaying plantar pressure. The system can realize the plantar pressure data acquisition, data storage, waveform display, and waveform playback. It was also shown that the testing results of the system were in line with the changing trend of normal gait, which conformed to human system engineering theory. It leads to the demonstration of system reliability. The system gives vivid and visual results, and provides a new method of how to measure foot-pressure and some references for the design of Insole System.

  19. Improvement of the accuracy of vapor pressure measurements by quartz membrane manometers

    Science.gov (United States)

    Rusin, A. D.

    2008-06-01

    The sensitivity of and instrumental errors in high-temperature vapor pressure measurements by two quartz crescent-shaped manometers of enhanced sensitivity were determined; the thermal drift of their zero pints was studied. The contributions of instrumental errors and thermal drift to the total sample variance of pressure were found. The main source of the total error in pressure was shown to be zero point thermal drift and errors in the determination of the position of the membrane pin. Compared with the usual design of these membrane manometers, sensitivity was higher 14.7 and 21.3 times, and measurement errors were lower 5.4 and 19 times, respectively. The two manometers studied gave pressure errors of 0.13 and 0.32 torr, respectively, at a 0.95 confidence probability.

  20. Spectral measurement of atmospheric pressure plasma by means of digital camera

    International Nuclear Information System (INIS)

    Ge Yuanjing; Zhang Guangqiu; Liu Yimin; Zhao Zhifa

    2002-01-01

    A digital camera measuring system has been used successfully to measure the space fluctuation behaviors of Induced Dielectric Barrier Discharge (IDBD) plasma at atmospheric pressure. The experimental results showed that: (1) The uniformity of electron temperature in space depends on discharge condition and structure of web electrode. For a certain web electrode the higher the discharge voltage is, the more uniform distribution of electron temperature in space will be. For a certain discharge the finer and denser the holes on web electrode are, the more uniform distribution of electron temperature in space will be. (2) Digital camera is an available equipment to measure some behaviors of the plasma working at atmospheric pressure

  1. Reliable blood pressure self-measurement in the obstetric waiting room

    DEFF Research Database (Denmark)

    Wagner, Stefan; Kamper, C. H.; Rasmussen, Niels H

    2014-01-01

    Background: Patients often fail to adhere to clinical recommendations when using current blood pressure self-measurement (BPSM) methods and equipment. As existing BPSM equipment is not able to detect non-adherent behavior, this could result in misdiagnosis and treatment error. To overcome...... patients scheduled for self-measuring their blood pressure (BP) in the waiting room at an obstetrics department's outpatient clinic to perform an additional BPSM using ValidAid. We then compared the automatically measured and classified values from ValidAid with our manual observations. Results: We found...

  2. Use of Repeated Blood Pressure and Cholesterol Measurements to Improve Cardiovascular Disease Risk Prediction

    DEFF Research Database (Denmark)

    Paige, Ellie; Barrett, Jessica; Pennells, Lisa

    2017-01-01

    The added value of incorporating information from repeated blood pressure and cholesterol measurements to predict cardiovascular disease (CVD) risk has not been rigorously assessed. We used data on 191,445 adults from the Emerging Risk Factors Collaboration (38 cohorts from 17 countries with data...... encompassing 1962-2014) with more than 1 million measurements of systolic blood pressure, total cholesterol, and high-density lipoprotein cholesterol. Over a median 12 years of follow-up, 21,170 CVD events occurred. Risk prediction models using cumulative mean values of repeated measurements and summary...... improvements were 0.0369 (95% CI: 0.0303, 0.0436) for the cumulative-means model and 0.0177 (95% CI: 0.0110, 0.0243) for the longitudinal model. In conclusion, incorporating repeated measurements of blood pressure and cholesterol into CVD risk prediction models slightly improves risk prediction....

  3. Non-invasive Measurement of Pressure Gradients in Pulsatile Flow using Ultrasound

    DEFF Research Database (Denmark)

    Olesen, Jacob Bjerring; Traberg, Marie Sand; Pihl, Michael Johannes

    2013-01-01

    This paper demonstrates how pressure gradients in a pulsatile flow environment can be measured non-invasively using ultrasound. The proposed method relies on vector velocity fields acquired from ultrasound data. 2-D flow data are acquired at 18-23 frames/sec using the Transverse Oscillation...... approach. Pressure gradients are calculated from the measured velocity fields using the Navier-Stokes equation. Velocity fields are measured during constant and pulsating flow on a carotid bifurcation phantom and on a common carotid artery in-vivo. Scanning is performed with a 5 MHz BK8670 linear...... transducer using a BK Medical 2202 UltraView Pro Focus scanner. The calculated pressure gradients are validated through a finite element simulation of the constant flow model. The geometry of the flow simulation model is reproduced using MRI data, thereby providing identical flow domains in measurement...

  4. Direct measurement of gas solubilities in polymers with a high-pressure microbalance

    DEFF Research Database (Denmark)

    von Solms, Nicolas; Nielsen, Johannes Kristoffer; Hassager, Ole

    2004-01-01

    Solubility and diffusion data are presented for methane and carbon dioxide gases in high-density polyethylene. The polymer was cut from extruded piping intended for use in offshore oil and gas applications. The measurements were carried out with a high-pressure microbalance. The properties were...... determined from 25 to 50degreesC and from 50 to 150 bar for methane and from 20 to 40 bar for carbon dioxide. In general, a good agreement was obtained with similar measurements reported in the literature. The solubility followed Henry's law (linear) dependence with pressure, except at high pressures...... for methane, for which negative deviations from Henry's law behavior were observed. The diffusion coefficients for each of the gases in the polymer were also measured with the balance, although the uncertainty was greater than for the solubility measurements. (C) 2003 Wiley Periodicals, Inc. J Appl Polyrn Sci...

  5. Diagnostic accuracy of laser Doppler flowmetry versus strain gauge plethysmography for segmental pressure measurement.

    Science.gov (United States)

    Høyer, Christian; Sandermann, Jes; Paludan, Jens Peder D; Pavar, Susanne; Petersen, Lars J

    2013-12-01

    To assess the diagnostic accuracy of laser Doppler flowmetry (LDF) with mercury-in-silastic strain gauge plethysmography (SGP) as a reference test for measuring the toe and ankle pressures in patients with known or suspected peripheral arterial disease (PAD). This was a prospective, randomized, blinded diagnostic accuracy study. Toe and ankle pressures were measured using both methods in 200 consecutive patients, who were recruited at our vascular laboratory over a period of 30 working days. Classification of PAD and critical limb ischemia (CLI) was made in accordance with TASC-II criteria. The LDF method demonstrated 5.8 mm Hg higher mean toe pressures than the SGP method for the right limb and 7.0 mm Hg for the left limb (both P pressures (both P > .129). The limits of agreement for the differences (SGP - LDF) were -31.7 to 20.2 mm Hg for right toe pressures, -28.0 to 14.0 mm Hg for left toe pressures, -25.5 to 22.8 mm Hg for right ankle pressures, and -26.9 to 24.6 mm Hg for left ankle pressures. A correlation analysis of the absolute pressures using the two methods showed an intraclass correlation coefficient of 0.902 (95% confidence interval [CI], 0.835-0.938) for right toe pressures, 0.919 (95% CI, 0.782-0.960) for the left toe pressures, 0.953 (95% CI, 0.937-0.965) for right ankle pressures, and 0.952 (95% CI, 0.936-0.964) for left ankle pressures. Cohen's Kappa showed an agreement in the diagnostic classification of κ = 0.775 (95% CI, 0.631-0.919) for PAD and κ = 0.780 (95% CI, 0.624-0.936) for CLI. LDF showed a good correlation with SGP over a wide range of toe and ankle pressures, as well as substantial agreement for the diagnostic classification of PAD including CLI. Copyright © 2013 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.

  6. Diabetic foot ulcer incidence in relation to plantar pressure magnitude and measurement location.

    Science.gov (United States)

    Ledoux, William R; Shofer, Jane B; Cowley, Matthew S; Ahroni, Jessie H; Cohen, Victoria; Boyko, Edward J

    2013-01-01

    We prospectively examined the relationship between site-specific peak plantar pressure (PPP) and ulcer risk. Researchers have previously reported associations between diabetic foot ulcer and elevated plantar foot pressure, but the effect of location-specific pressures has not been studied. Diabetic subjects (n=591) were enrolled from a single VA hospital. Five measurements of in-shoe plantar pressure were collected using F-Scan. Pressures were measured at 8 areas: heel, lateral midfoot, medial midfoot, first metatarsal, second through fourth metatarsal, fifth metatarsal, hallux, and other toes. The relationship between incident plantar foot ulcer and PPP or pressure-time integral (PTI) was assessed using Cox regression. During follow-up (2.4years), 47 subjects developed plantar ulcers (10 heel, 12 metatarsal, 19 hallux, 6 other). Overall mean PPP was higher for ulcer subjects (219 vs. 194kPa), but the relationship differed by site (the metatarsals with ulcers had higher pressure, while the opposite was true for the hallux and heel). A statistical analysis was not performed on the means, but hazard ratios from a Cox survival analysis were nonsignificant for PPP across all sites and when adjusted for location. However, when the metatarsals were considered separately, higher baseline PPP was significantly associated with greater ulcer risk; at other sites, this relationship was nonsignificant. Hazard ratios for all PTI data were nonsignificant. Location must be considered when assessing the relationship between PPP and plantar ulceration. © 2013.

  7. Soot particle size measurements in ethylene diffusion flames at elevated pressures

    KAUST Repository

    Steinmetz, Scott

    2016-05-07

    Soot particle size is investigated in laminar nitrogen-diluted ethylene coflow diffusion flames at 4, 8, 12 and 16 atm. Line of sight attenuation and scattering are used to measure two-dimensional soot volume fraction and particle size fields for the first time at elevated pressures. Soot volume fraction dependence on pressure is consistent with the observations of similar studies, scaling approximately with the square of pressure. Scattering intensity is analyzed through Rayleigh and Rayleigh-Debye-Gans polydisperse fractal aggregate theories to provide two estimates of particle size. An increase in overall particle sizes with pressure is found, consistent with similar one-dimensional studies. Particle diameters in the annulus of the flame increase faster with pressure than those on centerline. Contrary to previous studies, the dependence of particle size on pressure was found to taper off between 8 and 12 atm, with little observed growth beyond 12 atm. The measurements provide additional data for one of the International Sooting Flame (ISF) workshop\\'s target pressurized flames.

  8. Development and application of the condom catheter method for non-invasive measurement of bladder pressure

    NARCIS (Netherlands)

    R. van Mastrigt (Ron); J.J.M. Pel (Johan); J.W.N.C. Huang Foen Chung (John); P.A. de Zeeuw (Sandra)

    2009-01-01

    textabstractObjectives: A non-invasive method to measure the bladder pressure in males using a condom catheter has been developed. The measurement technique, its validation and limitations, a diagnostic nomogram to non-invasively diagnose bladder outlet obstruction (BOO), and results of large-scale

  9. A pitfall in the measurement of arterial blood pressure in the ischaemic limb during elevation

    DEFF Research Database (Denmark)

    Bülow, J; Jelnes, Rolf

    1987-01-01

    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 ...... extremity cannot be determined non-invasively by elevation of the extremity, probably due to collapse of segments of the vascular bed increasing the vascular resistance considerably....

  10. [SIMULTANEOUS MEASUREMENT OF INTRAVENTRICULAR AND PARENCHYMAL INTRACRANIAL PRESSURE IN PATIENTS WITH SEVERE TRAUMA BRAIN INJURY].

    Science.gov (United States)

    Oshorov, A V; Popugaev, K A; Savin, I A; Potapov, A A

    2016-01-01

    "Standard" assessment of ICP by measuring liquor ventricular pressure recently questioned. THE OBJECTIVE OF THE STUDY: Compare the values of ventricular and parenchymal ICP against the closure of open liquor drainage and during active CSF drainage. Examined 7 patients with TBI and intracranial hypertension syndrome, GCS 5.6 ± 1.2 points, 4.2 ± age 33 years. Compared parenchymal and ventricular ICP in three time periods: 1--during closure of ventricular drainage, 2--during of the open drains and drainage at the level of 14-15 mmHg, 3--during the period of active drainage. When comparing two methods of measurement used Bland-Altman method. 1. During time period of the closed drainage correlation coefficient was r = 0.83, p intracranial pressure is reduced. 3. During the active CSF drainage correlation between the two methods of measuring intracranial pressure can be completely lost. Under these conditions, CSF pressure is not correctly reflect the ICP 4. For an accurate and continuous measurement of intracranial pressure on the background of the active CSF drainage should be carried out simultaneous parenchymal ICP measurement.

  11. System for Rapid, Precise Modulation of Intraocular Pressure, toward Minimally-Invasive In Vivo Measurement of Intracranial Pressure.

    Directory of Open Access Journals (Sweden)

    Max A Stockslager

    Full Text Available Pathologic changes in intracranial pressure (ICP are commonly observed in a variety of medical conditions, including traumatic brain injury, stroke, brain tumors, and glaucoma. However, current ICP measurement techniques are invasive, requiring a lumbar puncture or surgical insertion of a cannula into the cerebrospinal fluid (CSF-filled ventricles of the brain. A potential alternative approach to ICP measurement leverages the unique anatomy of the central retinal vein, which is exposed to both intraocular pressure (IOP and ICP as it travels inside the eye and through the optic nerve; manipulating IOP while observing changes in the natural pulsations of the central retinal vein could potentially provide an accurate, indirect measure of ICP. As a step toward implementing this technique, we describe the design, fabrication, and characterization of a system that is capable of manipulating IOP in vivo with <0.1 mmHg resolution and settling times less than 2 seconds. In vitro tests were carried out to characterize system performance. Then, as a proof of concept, we used the system to manipulate IOP in tree shrews (Tupaia belangeri while video of the retinal vessels was recorded and the caliber of a selected vein was quantified. Modulating IOP using our system elicited a rapid change in the appearance of the retinal vein of interest: IOP was lowered from 10 to 3 mmHg, and retinal vein caliber sharply increased as IOP decreased from 7 to 5 mmHg. Another important feature of this technology is its capability to measure ocular compliance and outflow facility in vivo, as demonstrated in tree shrews. Collectively, these proof-of-concept demonstrations support the utility of this system to manipulate IOP for a variety of useful applications in ocular biomechanics, and provide a framework for further study of the mechanisms of retinal venous pulsation.

  12. Effect of patient positioning on toe pressure measurement using noninvasive vascular testing.

    Science.gov (United States)

    Sansosti, Laura E; Berger, Michael D; Gerrity, Michael A; Kelly, Patrick; Meyr, Andrew J

    2015-09-01

    Interpretation of digital pressure in the assessment of healing potential for diabetic foot disease has become common because of the potential for false elevation with the ankle-brachial index. However, the specific testing protocol for segmental Doppler examinations and photoplethysmography require patients to be in the supine position, with the lower limbs at heart level, in order to minimise the effect of hydrostatic pressure. This may be difficult in many patients with lower extremity pathology, particularly those who are nonambulatory, with painful wounds, or with orthopnea. In these situations, the noninvasive vascular test may be performed with the patient in a more comfortable position, which may include sitting in a wheelchair with the leg in a dependent position. The objective of this investigation was to evaluate the effect of patient positioning on measurement of the digital pressure. Hallux pressures were measured in 20 healthy volunteers in 3 variable positions of limb dependency. The mean±standard deviation of digital pressure for subjects while lying supine with the limb at heart level was 103.5±26.0 mmHg (the recommended position for performance of the test), while sitting upright with the limb level on the table was 130.6±27.9 mmHg (+26.2%, pposition was 169.8±30.8 mmHg (+64.1%, ppositioning has a significant effect on measurement of digital pressure.

  13. In situ gas analysis for high pressure applications using property measurements

    Science.gov (United States)

    Moeller, J.; Span, R.; Fieback, T.

    2013-10-01

    As the production, distribution, and storage of renewable energy based fuels usually are performed under high pressures and as there is a lack of in situ high pressure gas analysis instruments on the market, the aim of this work was to develop a method for in situ high pressure gas analysis of biogas and hydrogen containing gas mixtures. The analysis is based on in situ measurements of optical, thermo physical, and electromagnetic properties in gas mixtures with newly developed high pressure sensors. This article depicts the calculation of compositions from the measured properties, which is carried out iteratively by using highly accurate equations of state for gas mixtures. The validation of the method consisted of the generation and measurement of several mixtures, of which three are presented herein: a first mixture of 64.9 mol. % methane, 17.1 mol. % carbon dioxide, 9 mol. % helium, and 9 mol. % ethane at 323 K and 423 K in a pressure range from 2.5 MPa to 17 MPa; a second mixture of 93.0 mol. % methane, 4.0 mol. % propane, 2.0 mol. % carbon dioxide, and 1.0 mol. % nitrogen at 303 K, 313 K, and 323 K in a pressure range from 1.2 MPa to 3 MPa; and a third mixture of 64.9 mol. % methane, 30.1 mol. % carbon dioxide, and 5.0 mol. % nitrogen at 303 K, 313 K, and 323 K in a pressure range from 2.5 MPa to 4 MPa. The analysis of the tested gas mixtures showed that with measured density, velocity of sound, and relative permittivity the composition can be determined with deviations below 1.9 mol. %, in most cases even below 1 mol. %. Comparing the calculated compositions with the generated gas mixture, the deviations were in the range of the combined uncertainty of measurement and property models.

  14. [Measurement of tube cuff pressure levels in intensive care unit: considerations on the benefits of training].

    Science.gov (United States)

    Juliano, Silvia Renata Rezek; Juliano, Maria Cecília Rezek; Cividanes, Jose Paulo; Houly, João Geraldo Simões; Gebara, Otavio Celso Eluf; Cividanes, Gil Vicente L; Catão, Elaine C

    2007-09-01

    The tube cuff pressure directly transmitted on the tracheal wall in an irregular form can cause injuries and lead to bronchoaspiration. The aim of this study was to demonstrate that the implementation of routine tube cuff pressure measurements result in a reliable control to maintain the measurements within the parameters considered safe, thus preventing the described complications. A total of 3,195 tube cuff measurements were obtained from 1,194 male and female patients admitted at the Intensive Care Unit (ICU) and Coronary Unit (CU), who were undergoing mechanical ventilation with endotracheal prosthesis and tracheotomy cannula, during the morning and afternoon periods. From March to August 2005 the follow-up of the measurements obtained by the physical therapy professionals was carried out and it was observed that the measurements were irregular, on average, in 80% of the cases. Thus, a training program was established, which was focused on the Nursing Teams of the ICU and CU, consisting in providing directions for the adequate procedures performed at the bedside (in loco training). The training procedures were carried out at two different periods (morning and afternoon) in order to include the whole team. It is suggested that it is necessary to monitor tube cuff pressure through the implementation of routine measurements in the morning, afternoon and evening periods as a prophylactic measure, in order to prevent the possible complications of tracheal prosthesis balloon pressure.

  15. Wave Shape and Impact Pressure Measurements at a Rock Coast Cliff

    Science.gov (United States)

    Varley, S. J.; Rosser, N. J.; Brain, M.; Vann Jones, E. C.

    2016-02-01

    Rock coast research focuses largely on wave behaviour across beaches and shore platforms but rarely considers direct wave interaction with cliffs. Hydraulic action is one of the most important drivers of erosion along rock coasts. The magnitude of wave impact pressure has been shown by numerical and laboratory studies to be related to the wave shape. In deep water, a structure is only subjected to the hydrostatic pressure due to the oscillating clapotis. Dynamic pressures, related to the wave celerity, are exerted in shallower water when the wave is breaking at the point of impact; very high magnitude, short duration shock pressures are theorised to occur when the approaching wavefront is vertical. As such, wave shape may directly influence the potential of the impact to weaken rock and cause erosion. Measurements of impact pressure at coastal cliffs are limited, and the occurrence and influence of this phenomenon is currently poorly constrained. To address this, we have undertaken a field monitoring study on the magnitude and vertical distribution of wave impact pressures at the rocky, macro-tidal coastline of Staithes, North Yorkshire, UK. A series of piezo-resistive pressure transducers and a camera were installed at the base of the cliff during low tide. Transducers were deployed vertically up the cliff face and aligned shore-normal to capture the variation in static and dynamic pressure with height during a full spring tidal cycle. Five minute bursts of 5 kHz pressure readings and 4 Hz wave imaging were sampled every 30 minutes for six hours during high tide. Pressure measurements were then compensated for temperature and combined with wave imaging to produce a pressure time series and qualitative wave shape category for each wave impact. Results indicate the presence of a non-linear relationship between pressure impact magnitude, the occurrence of shock pressures, wave shape and tidal stage, and suggest that breaker type on impact (and controls thereof) may

  16. A new transducer for local load measurements of friction and roll pressure in cold flat rolling

    DEFF Research Database (Denmark)

    Lagergren, J.; Wanheim, Tarras; Precz, W.

    2006-01-01

    selected from a steady state with no disturbance from the material flow. The transducer was able to simultaneously measure both the normal pressure and the friction stress. An estimation of the coefficient of friction was accordingly performed. The new transducer works very well, it was seen to be robust......The only way to establish the true rolling pressure and the true friction condition in cold rolling is to conduct measurements in the roll bite. A new transducer design is therefore proposed, in order to overcome problems in previous measurements in the past 70 years. The new idea is to increase...... and able to avoid signal disturbance. The pressure and friction stress distribution results was as expected by the authors and showed good reproducibility, together with a proven agreement between recorded and simulated signals....

  17. High-pressure plastic scintillation detector for measuring radiogenic gases in flow systems

    CERN Document Server

    Schell, W R; Yoon, S R; Tobin, M J

    1999-01-01

    Radioactive gases are emitted into the atmosphere from nuclear electric power and nuclear fuel reprocessing plants, from hospitals discarding xenon used in diagnostic medicine, as well as from nuclear weapons tests. A high-pressure plastic scintillation detector was constructed to measure atmospheric levels of such radioactive gases by detecting the beta and internal conversion (IC) electron decays. Operational tests and calibrations were made that permit integration of the flow detectors into a portable Gas Analysis, Separation and Purification system (GASP). The equipment developed can be used for measuring fission gases released from nuclear reactor sources and/or as part of monitoring equipment for enforcing the Comprehensive Test Ban Treaty. The detector is being used routinely for in-line gas separation efficiency measurements, at the elevated operational pressures used for the high-pressure swing analysis system (2070 kPa) and at flow rates of 5-15 l/min . This paper presents the design features, opera...

  18. The corrosion rate measurement of Inconel 690 on high temperature and pressure by using CMS100

    International Nuclear Information System (INIS)

    Sriyono; Satmoko, Ari; Febrianto; Hidayati, N R; Arifal; Sumarno, Ady; Handoyo, Ismu; Prasetjo, Joko

    1999-01-01

    The corrosion rate measurement of Inconel 690 on high temperature and pressure had been done. By using an Autoclave, and temperature can be simulated. For reducing the pressure on Autoclave so its can be measure by Corrosion Measurement System 100(CMS100), the electrodes placement had designed and fabrication on the cover of Autoclave. The electrodes of CMS100 are reference electrode, working electrodes and counter electrodes. The electrodes placement are made and and designed on two packages, these are Salt bridge and Counter-specimen placement. From the result of testing these both of placement are able to 90 bar (pressure) and 280 C (temperature) operation rate measurement was done on temperature variation from 150 0C, 190 0C, 200 0C, 210 0C, 220 0C and 230 0C, and the solution is 0.1 ppm chloride. The pressure experiment is the pressure, which occurred in Autoclave. From the Tafel analysis, even through very little The corrosion current increased from 150 C to 230 C it is 2,54x10-10 a/cm2 to 1,62x10-9 A/cm2, but the the corrosion rate is still zero

  19. Measuring method and device for thickness of pad welded joint of reactor pressure vessel

    International Nuclear Information System (INIS)

    Ara, Katsuyuki; Nakajima, Nobuya; Ebine, Noriya.

    1995-01-01

    A magnetic yoke having an optional magnetic path length and a magnetic path cross section is disposed in close contact with or adjacent to the surface of the pad welded joint of a reactor pressure vessel, to form a magnetic path by the magnetic yoke and the reactor pressure vessel. Then, the magnetic path yoke is magnetized to measure a distribution of a magnetic field generated on the surface of the pad welded joint or its vicinity to which the magnetic yoke is adapted to be in close contact or come close. Since the geometrical dimensions and the magnetic performances of a material of the magnetic yoke and the pressure vessel are previously determined and, the measured magnetic distribution changes only by the thickness of the pad welded joint, the thickness of the pad welded joint of the pressure vessel can be determined. Accordingly, the measuring method of the present invention can measure the thickness of the pad welded joint of the pressure vessel at a desired practical accuracy and at a resolution power of, for example, 0.1mm relative to the thickness of the seat welded joint of 5 to 10mm. (N.H.)

  20. Using smartphone pressure sensors to measure vertical velocities of elevators, stairways, and drones

    Science.gov (United States)

    Monteiro, Martín; Martí, Arturo C.

    2017-01-01

    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 derived. The approximation considered is valid in the first hundred meters of the inner layers of the atmosphere. In addition to pressure, acceleration values were also recorded using the built-in accelerometer. Numerical integration was performed, obtaining both vertical velocity and altitude. We show that data obtained using the pressure sensor is significantly less noisy than that obtained using the accelerometer. Error accumulation is also evident in the numerical integration of the acceleration values. In the proposed experiments, the pressure sensor also outperforms GPS, because this sensor does not receive satellite signals indoors and, in general, the operating frequency is considerably lower than that of the pressure sensor. In the cases in which it is possible, comparison with reference values taken from the architectural plans of buildings validates the results obtained using the pressure sensor. This proposal is ideally performed as an external or outreach activity with students to gain insight about fundamental questions in mechanics, fluids, and thermodynamics.

  1. Validation of a new micro-manometer pressure sensor for cardiovascular measurements in mice.

    Science.gov (United States)

    Trevino, Rodolfo J; Jones, Douglas L; Escobedo, Daniel; Porterfield, John; Larson, Erik; Chisholm, Gary B; Barton, Amanda; Feldman, Marc D

    2010-01-01

    Abstract The Scisense (London, ON, Canada) micro-manometer pressure sensor is currently being used by investigators to evaluate cardiovascular physiology in mice, but has not been validated to date. The purpose of the current study is to compare the 1.2 F Scisense pressure sensor to the current gold standard produced by Millar Instruments (Houston, TX) (1.4 F). In vitro comparisons were preformed including temperature drift, frequency response analysis up to 250 Hz, and damping coefficient and natural frequency determined via a pop test. The authors also performed in vivo comparisons including pressure drift, dose-response studies to IV isoproterenol, maximum adrenergic stimulation with IV dobutamine, and simultaneous placement of both micro-manometer pressure sensors in the same intact murine hearts. The authors conclude that both sensors are equivalent, and that the Scisense pressure sensor represents an alternative to the current gold standard, the Millar micro-manometer pressure sensor for in vivo pressure measurements in the mouse.

  2. Measurement of response time and detection of degradation in pressure sensor/sensing-line systems

    International Nuclear Information System (INIS)

    Buchanan, M.E.; Miller, L.F.; Kerlin, T.W.; Ragan, G.; March-Leuba, J.; Thie, J.A.

    1985-01-01

    A team evaluated several methods for remote measurement of the response time and detection of degradation (blockage or air in lines) of pressure sensor/sensing line systems typical of nuclear power plants. A method was developed for obtaining the response time of force-balance pressure transmitters by briefly interrupting the power supply to the transmitter. The data thus generated are then analyzed in conjunction with a model to predict transmitter response to an actual pressure perturbation. The research team also evaluated a pressure perturbation method for determining the asymptotic delay time of a pressure-sensing line and found that this method yields accurate results for essentially unblocked sensing lines. However, these pressure perturbation tests are not recommended for use in nuclear power plants because they are difficult to implement on-line. A third method for remote measurement applied noise analysis method that yielded accurate estimates of asymptotic delay times for blockage or air in sensing lines. Even though noise analysis methods worked well in the laboratory, it is recommended that further evaluation be performed in operating nuclear plants. (orig.)

  3. Measurement of response time and detection of degradation in pressure sensor/sensing line systems

    International Nuclear Information System (INIS)

    Buchanan, M.E.; Miller, L.F.; Thie, J.A.; Kerlin, T.W.; Ragan, G.E.; March-Leuba, J.

    1985-09-01

    A team evaluated several methods for remote measurement of the response time and detection of degradation (blockage or air in lines) of pressure sensor/sensing line systems typical of nuclear power plants. A method was developed for obtaining the response time of force-balance pressure transmitters by briefly interrupting the power supply to the transmitter. The data thus generated are then analyzed in conjunction with a model to predict transmitter response to an actual pressure perturbation. The research team also evaluated a pressure perturbation method for determining the asymptotic delay time of a pressure-sensing line and found that this method yields accurate results for essentially unblocked sensing lines. However, these pressure perturbation tests are not recommended for use in nuclear power plants because they are difficult to implement on-line. A third method for remote measurement applied noise analysis methods that yielded accurate estimates of asymptotic delay times for blockage or air in sensing lines. Even though noise analysis methods worked well in the laboratory, it is recommended that further evaluation be performed in operating nuclear plants

  4. Comparison of pressure reconstruction approaches based on measured and simulated velocity fields

    Directory of Open Access Journals (Sweden)

    Manthey Samuel

    2017-09-01

    Full Text Available The pressure drop over a pathological vessel section can be used as an important diagnostic indicator. However, it cannot be measured non-invasively. Multiple approaches for pressure reconstruction based on velocity information are available. Regarding in-vivo data introducing uncertainty these approaches may not be robust and therefore validation is required. Within this study, three independent methods to calculate pressure losses from velocity fields were implemented and compared: A three dimensional and a one dimensional method based on the Pressure Poisson Equation (PPE as well as an approach based on the work-energy equation for incompressible fluids (WERP. In order to evaluate the different approaches, phantoms from pure Computational Fluid Dynamics (CFD simulations and in-vivo PC-MRI measurements were used. The comparison of all three methods reveals a good agreement with respect to the CFD pressure solutions for simple geometries. However, for more complex geometries all approaches lose accuracy. Hence, this study demonstrates the need for a careful selection of an appropriate pressure reconstruction algorithm.

  5. Pressure measurements of TO-phonon anharmonicity in isotopic ZnS

    Energy Technology Data Exchange (ETDEWEB)

    Tallman, R.E.; Weinstein, B.A. [SUNY at Buffalo, Department of Physics, Buffalo, NY 14260 (United States); Ritter, T.M. [Dept. of Chemistry and Physics, UNC Pembroke, NC 28372 (United States); Cantarero, A. [Dept. of Physics and Institute of Materials Science, University of Valencia (Spain); Serrano, J.; Lauck, R.; Cardona, M. [Max-Planck-Institut fuer Festkoerperforschung, 70569 Stuttgart (Germany)

    2004-03-01

    We have measured the dependence on pressure of the line-widths of the TO and LO Raman phonons of {beta}-ZnS. In order to enhance the phenomena observed, and to eliminate possible effects of isotopic disorder, we have measured a nearly isotopically pure crystal, {sup 68}Zn{sup 32}S. The strongly structured pressure effects observed are interpreted on the basis of anharmonic decay and the corresponding two-phonon density of states. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Adapting optical technologies for low pressure measurements in the marine industry (1-10 bar)

    Science.gov (United States)

    Sanmartin, D. Rodriguez; Lawal, A.; Awcock, G.; Busbridge, S.; Cooper, P.; Spenceley, J.

    2013-05-01

    Optical sensing is a very attractive technology option to design transducers for applications, such as the measurement of liquid level in oil fuel tanks, which require intrinsic safety and electromagnetic compatibility. PSM Instrumentation Ltd., an UK firm specialised in instrumentation for liquid level measurement for the marine industry and the University of Brighton are currently collaborating in a 2 year research programme funded by the UK government scheme Knowledge Transfer Partnerships. This paper evaluates how optical technologies could be used in pressure transducers, and their potential benefits, such as intrinsic safety compliance and low cost cabling, for low pressure applications such as fuel tank gauging for applications in the marine industry.

  7. Pressure Measurement in Supersonic Air Flow by Differential Absorptive Laser-Induced Thermal Acoustics

    Science.gov (United States)

    Hart, Roger C.; Herring, Gregory C.; Balla, Robert J.

    2007-01-01

    Nonintrusive, off-body flow barometry in Mach-2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorption measurement of the ultrasonic sound produced by the LITA pump process. Simultaneously, stream-wise velocity and static gas temperature of the same spatially-resolved sample volume were measured with this nonresonant time-averaged LITA technique. Mach number, temperature and pressure have 0.2%, 0.4%, and 4% rms agreement, respectively, in comparison with known free-stream conditions.

  8. In-situ measurement of response time of RTDs and pressure transmitters in nuclear power plants

    International Nuclear Information System (INIS)

    Hashemian, H.M.; Riner, J.L.

    1993-01-01

    Response time measurements are performed once every fuel cycle on most safety-related temperature and pressure sensors in a majority of nuclear power plants in the US. This paper provides a review of the methods that are used for these measurements. The methods are referred to as the Loop Current Step Response (LCSR) test, which is used for response time testing of temperature sensors, and noise analysis and power interrupt (PI) tests, which are used for response time testing of pressure, level, and flow transmitters

  9. A photostable bi-luminophore pressure-sensitive paint measurement system developed with mesoporous silica nanoparticles.

    Science.gov (United States)

    Mochizuki, Dai; Tamura, Shinichi; Yasutake, Hiroaki; Kataoka, Tomoharu; Mitsuo, Kazunori; Wada, Yuji

    2013-04-01

    The accurate and high-resolution measurement of surface pressure is achieved by a pressure/ temperature-sensitive composite paint (bi-PSP), whereas the pressure-sensitive dye photodegraded the temperature sensitive dye in close arrangement of both dyes. In the present study, an attempt was made to synthesize a homogeneous bi-PSP membrane without light-induced degradation of the dye using mesoporous silica. Mesoporous silica as a molecular sieve was the separation of pressure- and temperature-sensitive dyes. Both achievement of control of photodegradation in temperature-sensitive paints with molecule-screening capacity and macroscopically uniform placement of insoluble pigments in the respective solvent, was accomplished using the mesoporous silica nanoparticles in a compound PSP.

  10. [Effect of decreased ocular perfusion pressure on iris blood flow measured by laser Doppler flowmetry].

    Science.gov (United States)

    Chamot, S R; Movaffaghy, A; Petrig, B L; Riva, C E

    1999-05-01

    To determine whether iris blood flow (IBF) is regulated in response to an acute decrease in mean ocular perfusion pressure (PPm = MOAP-IOP, MOAP = mean ophthalmic arterial pressure) induced by increasing the intraocular pressure (IOP). Iris blood flow was measured using a slit lamp incorporating a laser Doppler flowmetry (LDF) module. The study was conducted on 12 normal volunteers (14 to 59 years old). IOP was raised using a scleral suction cup. In Exp. #1, the suction pressure was successively raised in steps of 50 to 100 mm Hg, each lasting about 10 sec, until IOP reached the MOAP level. In Exp. #2, the suction was raised to 200 mm Hg in 4 successive steps of 2 min duration. In Exp. #1, no significant change of IBF was observed for small decreases of PPm ( 23%).

  11. Pressure measurements in the AGS Booster ultra-high vacuum system

    International Nuclear Information System (INIS)

    Gabusi, J.; Geller, J.; Hseuh, H.C.; Mapes, M.; Stattel, P.

    1992-01-01

    An average pressure of mid 10 -11 Torr has been achieved and maintained in the AGS Booster ring vacuum system during its first year of operation. This ultra-high vacuum system is monitored through remote controlled Bayard-Alpert Gauges (BAGs). The characteristics of the pressure measurements with BAGs over the long cable lengths (up to 200 m) and under various accelerator operating conditions will be described. Two types of noise in the pressure readouts have been identified; the electromagnetic interference (EMI) associated with the acceleration cycles of the Booster and the environment noise associated with the temperature of the collector cables. The magnitude of the noise pickup depends on the routing of the collector cables and reaches the equivalent pressure of low 10 -9 Torr

  12. Cuffed endotracheal tubes in infants and children: should we routinely measure the cuff pressure?

    Science.gov (United States)

    Tobias, Joseph D; Schwartz, Lawrence; Rice, Julie; Jatana, Kris; Kang, D Richard

    2012-01-01

    Over the past 5 years, there has been a change in the clinical practice of pediatric anesthesiology with a transition to the use of cuffed instead of uncuffed endotracheal tubes in infants and children. However, there are few studies evaluating the current practices of inflation of these cuffs and the intracuff pressures. There was no change dictated in clinical practice for these patients. During the first 30 min of the case, the pressure in the cuff was measured using a hand held manometer. Additional data collected included the patient's demographic data (age, weight, and gender), the size of the ETT, whether nitrous oxide was in use, whether the patient was breathing spontaneously or undergoing positive pressure ventilation, and the type of anesthesia provider (resident, fellow, CRNA or SRNA). The cohort for the study included 200 patients ranging in age from 1 month to 17 years and in weight from 3.5 to 99.1 kg. The average cuff pressure was 23 ± 22 cmH(2)O in the total cohort of 200 patients. The cuff pressure was ≥ 30 cmH(2)O in 47 of the 200 patients (23.5%). The average cuff pressure was significantly higher in patients who were 8 years of age or greater compared to younger patients. Additionally, there were significantly more patients with a cuff pressure ≥ 30 cmH(2)O in the ≥ 8 year old age group. Although no difference in the mean cuff pressure was noted when comparing staff anesthesia providers (pediatric anesthesiologist or CRNA) versus trainees (SRNA, anesthesiology resident, medical student or pediatric anesthesiology fellow), the incidence of significantly excessive cuff pressures (≥ 60 cmH(2)O) was higher in the trainee group versus the faculty group (12 of 99 versus 2 of 101, ppressure greater than the generally recommended upper limit of 30 cmH(2)O. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  13. Direct measurement of osmotic pressure of glycosaminoglycan solutions by membrane osmometry at room temperature.

    Science.gov (United States)

    Chahine, Nadeen O; Chen, Faye H; Hung, Clark T; Ateshian, Gerard A

    2005-09-01

    Articular cartilage is a hydrated soft tissue composed of negatively charged proteoglycans fixed within a collagen matrix. This charge gradient causes the tissue to imbibe water and swell, creating a net osmotic pressure that enhances the tissue's ability to bear load. In this study we designed and utilized an apparatus for directly measuring the osmotic pressure of chondroitin sulfate, the primary glycosaminoglycan found in articular cartilage, in solution with varying bathing ionic strength (0.015 M, 0.15 M, 0.5 M, 1 M, and 2 M NaCl) at room temperature. The osmotic pressure (pi) was found to increase nonlinearly with increasing chondroitin sulfate concentration and decreasing NaCl ionic bath environment. Above 1 M NaCl, pi changes negligibly with further increases in salt concentration, suggesting that Donnan osmotic pressure is negligible above this threshold, and the resulting pressure is attributed to configurational entropy. Results of the current study were also used to estimate the contribution of osmotic pressure to the stiffness of cartilage based on theoretical and experimental considerations. Our findings indicate that the osmotic pressure resulting from configurational entropy is much smaller in cartilage (based on an earlier study on bovine articular cartilage) than in free solution. The rate of change of osmotic pressure with compressive strain is found to contribute approximately one-third of the compressive modulus (H(A)(eff)) of cartilage (Pi approximately H(A)(eff)/3), with the balance contributed by the intrinsic structural modulus of the solid matrix (i.e., H(A) approximately 2H(A)(eff)/3). A strong dependence of this intrinsic modulus on salt concentration was found; therefore, it appears that proteoglycans contribute structurally to the magnitude of H(A), in a manner independent of osmotic pressure.

  14. A Cuffless Blood Pressure Measurement Based on the Impedance Plethysmography Technique

    Directory of Open Access Journals (Sweden)

    Shing-Hong Liu

    2017-05-01

    Full Text Available In the last decade, cuffless blood pressure measurement technology has been widely studied because it could be applied to a wearable apparatus. Electrocardiography (ECG, photo-plethysmography (PPG, and phonocardiography are always used to detect the pulse transit time (PTT because the changed tendencies of the PTT and blood pressure have a negative relationship. In this study, the PPG signal was replaced by the impedance plethysmography (IPG signal and was used to detect the PTT. The placement and direction of the electrode array for the IPG measurement were discussed. Then, we designed an IPG ring that could measure an accurate IPG signal. Twenty healthy subjects participated in this study. The changes in blood pressure after exercise were evaluated through the changes of the PTT. The results showed that the change of the systolic pressure had a better relationship with the change of the PTTIPG than that of the PTTPPG (r = 0.700 vs. r = 0.450. Moreover, the IPG ring with spot electrodes would be more suitable to develop with the wearable cuffless blood pressure monitor than the PPG sensor.

  15. Noninvasive measurement of rat intraocular pressure with the Tono-Pen.

    Science.gov (United States)

    Moore, C G; Milne, S T; Morrison, J C

    1993-02-01

    The purpose of this study was to evaluate the Tono-Pen 2 tonometer for measuring intraocular pressure (IOP) in the living rat eye. One eye from each of 20 adult, anesthetized brown Norway rats (group 1) was cannulated and simultaneously connected to a syringe and a pressure transducer with a chart recorder. We increased IOP from 15 to 45 mmHg in 5-mmHg increments and obtained 15 consecutive readings (ignoring instrument-generated averages) at each pressure increment with a Tono-Pen 2 tonometer. To test the tonopen's ability to measure unknown IOP, transducer pressures were varied randomly in 20 additional animals (group 2), and tonopen readings were obtained in masked fashion. Plotting the mean tonopen readings for each animal against transducer IOP produced a regression formula of y = 4.54 + 0.79x (r = 0.98). Mean group 2 tonopen values plotted against transducer IOP yielded a regression formula of y = 4.75 + 0.78x (r = 0.94). A method comparison analysis showed that the tonopen significantly overestimates pressures at low IOP ( or = 30 mmHg). Using two-way analysis of variance, it was determined that the group 2 data did not differ significantly from the group 1 data (P > or = 0.76). Because of this consistency, we generated a correction factor with 95% prediction intervals for Tono-Pen readings. The Tono-Pen 2 can be used reliably to measure IOP in the normal rat eye.

  16. Interfacial tension measurement between CO2 and brines under high temperature and elevated pressure conditions

    Science.gov (United States)

    Li, X.; Boek, E. S.; Maitland, G. C.; Trusler, J. P. M.

    2012-04-01

    We have investigated the dependence of interfacial tension of (CO2 + brine) on temperature, pressure and salinity (including both salt type and molality) over the range of conditions applicable to CO2 storage in saline aquifers. The study covered a wide range of measurements of the interfacial tensions between carbon dioxide and (NaCl + KCl)(aq), CaCl2(aq), MgCl2(aq), Na2SO4(aq), KHCO3(aq), NaHCO3(aq) and two laboratory constructed brines with molality ranging from (0.3 to 5.0) mol·kg-1. The measurements were made at temperatures between (298 and 448) K at various pressures up to 50 MPa, using the pendant drop method in a high-pressure view cell filled with water-saturated CO2. The drop to be imaged was created by injecting brine from a high-pressure syringe pump into a capillary sealed through the top of the cell. The expanded uncertainties of the experimental state variables at 95 % confidence are +0.05 K in temperature and +70 kPa in pressure. For the interfacial tension, the overall expanded relative uncertainty at 95 % confidence was +1.6%. The experimental results show that interfacial tension for all the systems increases linearly with molality, indicating that relatively few measurements and simple interpolation procedures are adequate for describing this property accurately over wide ranges of conditions.

  17. Abstract of report on advances in measuring, regulation, and automatic control of operations in high pressure plants

    Energy Technology Data Exchange (ETDEWEB)

    1942-10-17

    The topics of this report are temperature measurements, pressure and differential-pressure measurements, and liquid level measurement. The section on temperature measurements discusses increasing accuracy of measurements by counter-connecting a constant tension (potential) or using resistance thermometers, increasing speed of measurements, and automatic temperature control. The pressure measurements section discusses an increase in time of use by using a spring manometer and an increase in accuracy by using a piston manometer. The differential-pressure measurements section discusses a piston differential manometer that permitted measurement of the pressure drop in all high pressure stalls daily from point to point so that irregularities caused by clogging of preheater tubes or closing of heat exchangers could be corrected by proper measures. The Oppau liquid level measurement and the Leuna liquid level measurement are mentioned but no discussion or any information is given. The increase in accuracy of pressure and temperature measurement meant that pressures could be measured within a fraction of an atmosphere and temperatures could be measured within about half of a degree C (actually measured as fractions of a tenth-millivolt by thermocouple elements). Additional developments included the use of photoelectric temperature measurement methods and the use of automatic devices for checking in regular rotation all of the thermocouple elements for indications of excessive temperature rise.

  18. Pulse Oximeter Derived Blood Pressure Measurement in Patients With a Continuous Flow Left Ventricular Assist Device.

    Science.gov (United States)

    Hellman, Yaron; Malik, Adnan S; Lane, Kathleen A; Shen, Changyu; Wang, I-Wen; Wozniak, Thomas C; Hashmi, Zubair A; Munson, Sarah D; Pickrell, Jeanette; Caccamo, Marco A; Gradus-Pizlo, Irmina; Hadi, Azam

    2017-05-01

    Currently, blood pressure (BP) measurement is obtained noninvasively in patients with continuous flow left ventricular assist device (LVAD) by placing a Doppler probe over the brachial or radial artery with inflation and deflation of a manual BP cuff. We hypothesized that replacing the Doppler probe with a finger-based pulse oximeter can yield BP measurements similar to the Doppler derived mean arterial pressure (MAP). We conducted a prospective study consisting of patients with contemporary continuous flow LVADs. In a small pilot phase I inpatient study, we compared direct arterial line measurements with an automated blood pressure (ABP) cuff, Doppler and pulse oximeter derived MAP. Our main phase II study included LVAD outpatients with a comparison between Doppler, ABP, and pulse oximeter derived MAP. A total of five phase I and 36 phase II patients were recruited during February-June 2014. In phase I, the average MAP measured by pulse oximeter was closer to arterial line MAP rather than Doppler (P = 0.06) or ABP (P < 0.01). In phase II, pulse oximeter MAP (96.6 mm Hg) was significantly closer to Doppler MAP (96.5 mm Hg) when compared to ABP (82.1 mm Hg) (P = 0.0001). Pulse oximeter derived blood pressure measurement may be as reliable as Doppler in patients with continuous flow LVADs. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  19. Pressure drop and arterial compliance - Two arterial parameters in one measurement.

    Science.gov (United States)

    Rotman, Oren M; Zaretsky, Uri; Shitzer, Avraham; Einav, Shmuel

    2017-01-04

    Coronary artery pressure-drop and distensibility (compliance) are two major, seemingly unrelated, parameters in the cardiovascular clinical setting, which are indicative of coronary arteries patency and atherosclerosis severity. While pressure drop is related to flow, and therefore serves as a functional indicator of a stenosis severity, the arterial distensibility is indicative of the arterial stiffness, and hence the arterial wall composition. In the present study, we hypothesized that local pressure drops are dependent on the arterial distensibility, and hence can provide information on both indices. The clinical significance is that a single measurement of pressure drop could potentially provide both functional and bio-mechanical metrics of lesions, and thus assist in real-time decision making prior to stenting. The goal of the current study was to set the basis for understanding this relationship, and define the accuracy and sensitivity required from the pressure measurement system. The investigation was performed using numerical fluid-structure interaction (FSI) simulations, validated experimentally using our high accuracy differential pressure measurement system. Simplified silicone mock coronary arteries with zero to intermediate size stenoses were used, and various combinations of arterial distensibility, diameter, and flow rate were simulated. Results of hyperemic flow cases were also compared to fractional flow reserve (FFR). The results indicate the potential clinical superiority of a high accuracy pressure drop-based parameter over FFR, by: (i) being more lesion-specific, (ii) the possibility to circumvent the FFR dependency on pharmacologically-induced hyperemia, and, (iii) by providing both functional and biomechanical lesion-specific information. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Human gallbladder pressure and volume: validation of a new direct method for measurements of gallbladder pressure in patients with acute cholecystitis

    DEFF Research Database (Denmark)

    Borly, L; Højgaard, L; Grønvall, S

    1996-01-01

    Increased gallbladder (GB) pressure is probably a part of the pathogenesis of acute cholecystitis, and measurements of GB pressure might therefore be of interest. The aim of this study was to validate a microtip pressure transducer for intraluminal GB pressure measurements. In vitro precision...... and accuracy was within 0.2 mmHg, (SD) and 0.6 +/- 0.1 mmHg (mean +/- SD), respectively. Pressure rise rate was 24.8 +/- 5.5 mmHg s-1. Zero drift was in the range 0.3 +/- 0.4 to 0.8 +/- 0.9 mmHg (mean +/- SD). GB pressure was investigated in 16 patients with acute cholecystitis treated with percutaneous...

  1. LB03.04: SPHYGMOMANOMETER CUFF CONSTRUCTION AND MATERIALS AFFECT TRANSMISSION OF PRESSURE FROM CUFF TO ARTERIAL WALL. FINITE ELEMENT ANALYSIS OF HUMAN PRESSURE MEASUREMENTS AND DICOM DATA.

    Science.gov (United States)

    Lewis, P; Naqvi, S; Mandal, P; Potluri, P

    2015-06-01

    Sphygmomanometer cuff pressure during deflation is assumed to equal systolic arterial pressure at the point of resumption of flow. Previous studies demonstrated that pressure decreases with increasing depth of soft tissues whilst visco-elastic characteristics of the arm tissue cause spatial and temporal variation in pressure magnitude. These generally used non-anatomical axisymmetrical arm simulations without incorporating arterial pressure variation. We used data from a volunteer's Magnetic Resonance (MR) arm scan and investigated the effect of variations in cuff materials and construction on the simulated transmission of pressure from under the cuff to the arterial wall under sinusoidal flow conditions. Pressure was measured under 8 different cuffs using Oxford Pressure Monitor Sensors placed at 90 degrees around the mid upper arm of a healthy male. Each cuff was inflated 3 times to 155 mmHg and then deflated to zero with 90 seconds between inflations. Young's modulus, flexural rigidity and thickness of each cuff was measured.Using DICOM data from the MR scan of the arm, a 3D model was derived using ScanIP and imported into Abaqus for Finite Element Analysis (FEA). Published mechanical properties of arm tissues and geometric non-linearity were assumed. The measured sub-cuff pressures were applied to the simulated arm and pressure was calculated around the brachial arterial wall. which was loaded with a sinusoidal pressure of 125/85 mmHg. FEA estimates of pressure around the brachial artery cuffs varied by up to 27 mmHg SBP and 17 mmHg DBP with different cuffs. Pressures within the cuffs varied up to 27 mmHg. Pressure transmission from the cuff to the arterial surface achieved a 95% transmission ratio with one rubber-bladdered cuff but varied between 76 and 88% for the others. Non-uniform pressure distribution around the arterial wall was strongly related to cuff fabric elastic modulus. Identical size cuffs with a separate rubber bladder produced peri

  2. An Investigation of Pulse Transit Time as a Non-Invasive Blood Pressure Measurement Method

    International Nuclear Information System (INIS)

    McCarthy, B M; O'Flynn, B; Mathewson, A

    2011-01-01

    The objective of this paper is to examine the Pulse Transit Method (PTT) as a non-invasive means to track Blood Pressure over a short period of time. PTT was measured as the time it takes for an ECG R-wave to propagate to the finger, where it is detected by a photoplethysmograph sensor. The PTT method is ideal for continuous 24-hour Blood Pressure Measurement (BPM) since it is both cuff-less and non-invasive and therefore comfortable and unobtrusive for the patient. Other techniques, such as the oscillometric method, have shown to be accurate and reliable but require a cuff for operation, making them unsuitable for long term monitoring. Although a relatively new technique, the PTT method has shown to be able to accurately track blood pressure changes over short periods of time, after which re-calibration is necessary. The purpose of this study is to determine the accuracy of the method.

  3. Pressurizer level measurement inside PWR nuclear plant using resistance type heat sensors

    International Nuclear Information System (INIS)

    El Moussaoui, Ahmed.

    1982-06-01

    The accident that occured in 1979 to the PWR type nuclear reactor, Three-Mile Island 2, has drawn attention to the maladjustement of the differentiel pressure level detector installed in nuclear plants on the market. A system is presented here for measuring the level in pressurizers based on measurements of the heat resistance of the boundary layer existing between the heated sensor and the fluid mass in the vessel. The sensor consists of a 3 cm diameter cylindrical insulator support around which a 0.1 mm diameter platinum filament is wound. This filament simultaneously fulfills heating and transducer functions. To verify the feasibility of the resistant type heat sensor a test system, which provides water and steam under pressure was realised. Static and dynamic tests have shown that the principle of the resistant heat sensor is viable and can be used to obtain level informations [fr

  4. Proving diamonds under ultra-high pressure with sound velocity measurements

    Science.gov (United States)

    Shigemori, Keisuke; Shimizu, Katsuya; Asakura, Yasuhiro; Sakaiya, Tatsuhiro; Kondo, Tadashi; Hironaka, Yoichiro; Irifune, Tetsuo; Sumiya, Hitoshi; Kadono, Toshihiko; Azechi, Hiroshi

    2014-10-01

    Diamond under terapascal (TPa) regime is of great interest on its phase transition to a post diamond phase. Many experimental works have been done on the diamond at the TPa regime by measuring the shock parameters (shock velocity, particle velocity). We measured sound velocities of shock-compressed diamond under several pressures by means of x-ray backlighting technique. Experiments were done on GEKKO-HIPER laser irradiation facility at Institute of Laser Engineering, Osaka University. We obtained sound velocities at a pressure of 0.4 - 2.0 TPa by changing the laser intensity. The experimental sound velocity suggests that a clear discontinuity at around 0.7 TPa where the melting of the diamond starts. The sound velocity drops then slightly increases with increasing pressure. The slope of the sound velocity over 1 TPa is lower than that under 0.7 TPa, indicating the melting of the diamond.

  5. Analysis of body imbalance in various writing sitting postures using sitting pressure measurement.

    Science.gov (United States)

    Lee, Dong-Eun; Seo, Sang-Min; Woo, Hee-Soon; Won, Sung-Yun

    2018-02-01

    [Purpose] This study set out to substantiate the importance of the right sitting posture by measuring the sitting pressure. It also described the influence of an imbalanced sitting posture on the body. [Subjects and Methods] The subjects included 30 healthy adults. A pressure mapping system was used to measure the sitting pressure in the right, one side prone, chin propped, and slumped sitting positions. [Results] The WDI (X AP ) showed a statistically significant difference between the 3 incorrect postures (one side prone, chin propped, and slumped sitting) and the right sitting posture. With regard to the WDI (X LR ), there was a statistically significant difference between the right sitting posture and the one side prone sitting posture only. [Conclusion] One side prone sitting was found to affect the body balance most adversely. This imbalanced posture may have an indirect effect on chronic diseases. The results prove that it is important to assume a proper posture to maintain body balance.

  6. An Investigation of Pulse Transit Time as a Non-Invasive Blood Pressure Measurement Method

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, B M; O' Flynn, B; Mathewson, A, E-mail: brian.mccarthy@tyndall.ie [Tyndall National Institute, UCC, Lee Maltings, Prospect Row, Cork (Ireland)

    2011-08-17

    The objective of this paper is to examine the Pulse Transit Method (PTT) as a non-invasive means to track Blood Pressure over a short period of time. PTT was measured as the time it takes for an ECG R-wave to propagate to the finger, where it is detected by a photoplethysmograph sensor. The PTT method is ideal for continuous 24-hour Blood Pressure Measurement (BPM) since it is both cuff-less and non-invasive and therefore comfortable and unobtrusive for the patient. Other techniques, such as the oscillometric method, have shown to be accurate and reliable but require a cuff for operation, making them unsuitable for long term monitoring. Although a relatively new technique, the PTT method has shown to be able to accurately track blood pressure changes over short periods of time, after which re-calibration is necessary. The purpose of this study is to determine the accuracy of the method.

  7. Measurement and correlation of vapour pressures of pyridine and thiophene with [EMIM][SCN] ionic liquid

    International Nuclear Information System (INIS)

    Khelassi-Sefaoui, Asma; Mutelet, Fabrice; Mokbel, Ilham; Jose, Jacques; Negadi, Latifa

    2014-01-01

    Highlights: • VLE of (pyridine + [EMIM][SCN]), or (thiophene + [EMIM][SCN]) binary mixtures were measured. • The investigated temperatures are 273 K to 363 K. • The PC-SAFT equation of state has been used to correlate the vapour pressures of the binary systems. - Abstract: In this work (vapour + liquid) equilibrium (VLE) measurements were performed on binary systems of the ionic liquid 1-ethyl-3-methylimidazolium thiocynate [EMIM][SCN] with thiophene or pyridine at pressures close to the atmospheric pressure using a static device at temperatures between 273 K and 363 K. Experimental data were correlated by the PC-SAFT EoS. The binary interaction parameters k ij were optimised on experimental VLE data. The results obtained for the two binary mixtures studied in this paper indicate that the PC-SAFT EoS can be used to represent systems containing ionic liquids

  8. Pressure measurement of the synchrotron light source PF-AR by cold cathode gauges

    CERN Document Server

    Tanimoto, Y; Hori, Y

    2003-01-01

    Synchrotron light source PF-AR was improved to realize higher performance in 2001. This improvement involved the renewal of the entire vacuum system to attain lower vacuum pressure for required beam lifetime. Thermal cathode ionization gauges, the most suitable gauges for the pressure measurement in the new system, were unacceptable because of both possible radiation damage to the controllers and the restriction of the budget. Cold cathode gauges (CCGs) were then chosen for the new system, while they usually have instability in the pressure range of 10 sup - sup 7 Pa and lower. For the solution of this problem, we adopted the improved cold cathode gauges that hold the Penning discharge even at 10 sup - sup 8 Pa and acquired calibration data with a pre-calibrated B-A gauge. We have originally designed CCG controllers using the calibration data, which enabled the reliable measurement in 10 sup - sup 8 Pa range. (author)

  9. Evaluation of Pressure Pain Threshold as a Measure of Perceived Stress and High Job Strain

    DEFF Research Database (Denmark)

    Hven, Lisbeth; Frost, Poul; Bonde, Jens Peter Ellekilde

    2017-01-01

    OBJECTIVE: To investigate whether pressure pain threshold (PPT), determined by pressure algometry, can be used as an objective measure of perceived stress and job strain. METHODS: We used cross-sectional base line data collected during 1994 to 1995 within the Project on Research and Intervention...... in Monotonous work (PRIM), which included 3123 employees from a variety of Danish companies. Questionnaire data included 18 items on stress symptoms, 23 items from the Karasek scale on job strain, and information on discomfort in specified anatomical regions was also collected. Clinical examinations included...... pressure pain algometry measurements of PPT on the trapezius and supraspinatus muscles and the tibia. Associations of stress symptoms and job strain with PPT of each site was analyzed for men and women separately with adjustment for age body mass index, and discomfort in the anatomical region closest...

  10. Drop break-up and pressure measurements in a microfluidic device

    Science.gov (United States)

    Protiere, Suzie; Stone, Howard A.; Weitz, David A.

    2008-11-01

    We study experimentally the flow of an emulsion passing through one or a few constrictions placed in a microfluidic channel. Using a high-speed differential manometer placed in the same device (M. Abkarian et al. PNAS 200:16407104 (2006)) we have measured the dynamic pressure as a drop breaks up when it meets one or several constrictions. We can then study how a global measurement of the pressure drop indicates the sequence of phenomena occurring in the channel (breakup, trapped and squeezed drops etc.). In a separate set of experiments with a microfluidic model of a two-dimensional porous medium through which drops flow we can observe the various phenomena and thus correlate the pressure fluctuations to single events at the pore scale.

  11. Pressure transducer used for measuring close-in shock waves of nuclear explosions in the atmosphere

    International Nuclear Information System (INIS)

    Lin, J.; Zhou, Z.

    1985-01-01

    This paper introduces a variable reluctance pressure transducer. It has been successfully used for the measurement of close-in shock waves of nuclear explosions in the atmosphere. This transducer's highest pressure range is 100kg/cm 2 and its response rise time for all ranges is lms. It uses a specially made oil-filled pressure which allows the transducer to be able to realize underground installation. In this way, it can endure the intense nuclear radiation of nuclear explosions without losing its fast speed response characteristics. This transducer has undergone a series of environmental tests and dynamic standardizations. Therefore, it was used to measure the complete waveform of shock wave overpressure in areas near the fire ball of nuclear explosions. This paper lists the test data of a group of nuclear explosion tests

  12. Repeated Blood Pressure Measurements in Childhood in Prediction of Hypertension in Adulthood.

    Science.gov (United States)

    Oikonen, Mervi; Nuotio, Joel; Magnussen, Costan G; Viikari, Jorma S A; Taittonen, Leena; Laitinen, Tomi; Hutri-Kähönen, Nina; Jokinen, Eero; Jula, Antti; Cheung, Michael; Sabin, Matthew A; Daniels, Stephen R; Raitakari, Olli T; Juonala, Markus

    2016-01-01

    Hypertension may be predicted from childhood risk factors. Repeated observations of abnormal blood pressure in childhood may enhance prediction of hypertension and subclinical atherosclerosis in adulthood compared with a single observation. Participants (1927, 54% women) from the Cardiovascular Risk in Young Finns Study had systolic and diastolic blood pressure measurements performed when aged 3 to 24 years. Childhood/youth abnormal blood pressure was defined as above 90th or 95th percentile. After a 21- to 31-year follow-up, at the age of 30 to 45 years, hypertension (>140/90 mm Hg or antihypertensive medication) prevalence was found to be 19%. Carotid intima-media thickness was examined, and high-risk intima-media was defined as intima-media thickness >90th percentile or carotid plaques. Prediction of adulthood hypertension and high-risk intima-media was compared between one observation of abnormal blood pressure in childhood/youth and multiple observations by improved Pearson correlation coefficients and area under the receiver operating curve. When compared with a single measurement, 2 childhood/youth observations improved the correlation for adult systolic (r=0.44 versus 0.35, Phypertension in adulthood (0.63 for 2 versus 0.60 for 1 observation, P=0.003). When compared with 2 measurements, third observation did not provide any significant improvement for correlation or prediction (P always >0.05). A higher number of childhood/youth observations of abnormal blood pressure did not enhance prediction of adult high-risk intima-media thickness. Compared with a single measurement, the prediction of adult hypertension was enhanced by 2 observations of abnormal blood pressure in childhood/youth. © 2015 American Heart Association, Inc.

  13. Cardiovascular pressure measurement in safety assessment studies: technology requirements and potential errors.

    Science.gov (United States)

    Sarazan, R Dustan

    2014-01-01

    In the early days of in vivo nonclinical pressure measurement, most laboratories were required to have considerable technical/engineering expertise to configure and maintain pressure transducers, amplifiers, tape recorders, chart recorders, etc. Graduate students and postdoctoral fellows typically had some training in the requirements and limitations of the technology they used and were closely engaged in the collection and evaluation of data from their own experiments. More recently, pressure sensing telemetry and data acquisition/analysis systems are provided by vendors as turnkey systems, often resulting in a situation where users are less familiar with the technicalities of their operation. Also, investigators are now more likely to be absent and rely on technical staff for the collection of raw in vivo pressure data from their experiments than in the past. Depending on the goals of an experiment, an investigator may require the measurement of a variety of different pressure parameters, over varying periods of time. A basic understanding of the requirements and limitations that can affect the accuracy and precision of these parameters is important to ensure that the results and conclusions from an experiment are reliable. Factors to consider include the possibility of hydrostatic pressure effects from blood inside the vasculature of the animal, depending on the location of the sensor, as well as from fluid inside a fluid-filled catheter system; long-term stability (lack of drift) of a sensor over time, which can affect the interpretation of absolute pressure changes over a prolonged experiment; frequency response of the sensor and associated electronics; and the phase shift that occurs depending on location of the sensor in the vasculature or because of a fluid-filled catheter system. Each of these factors is discussed, and the particular requirements of frequency response as applied to the measurement of cardiac left ventricular pressure are emphasized. When

  14. Atmospheric Airborne Pressure Measurements Using the Oxygen A Band for the ASCENDS Mission

    Science.gov (United States)

    Riris, Haris; Rodriguez, Mike; Stephen, Mark; Hasselbrack, William; Allan, Graham; Mao, Jiamping,; Kawa, Stephan R.; Weaver, Clark J.

    2011-01-01

    We report on airborne atmospheric pressure measurements using new fiber-based laser technology and the oxygen A-band at 765 nm. Remote measurements of atmospheric temperature and pressure are required for a number of NASA Earth science missions and specifically for the Active Sensing of CO2 Emissions Over Nights, Days, and Seasons (ASCENDS) mission. Accurate measurements of tropospheric CO2 on a global scale are very important in order to better understand its sources and sinks and to improve predictions on any future climate change. The ultimate goal of a CO2 remote sensing mission, such as ASCENDS, is to derive the CO2 concentration in the atmosphere in terms of mole fraction in unit of parts-per-million (ppmv) with regard to dry air. Therefore, both CO2 and the dry air number of molecules in the atmosphere are needed in deriving this quantity. O2 is a stable molecule and uniformly mixed in the atmosphere. Measuring the O2 absorption in the atmosphere can thus be used to infer the dry air number of molecules and then used to calculate CO2 concentration. With the knowledge of atmospheric water vapor, we can then estimate the total surface pressure needed for CO2 retrievals. Our work, funded by the ESTO IIP program, uses fiber optic technology and non-linear optics to generate 765 nm laser radiation coincident with the Oxygen A-band. Our pulsed, time gated technique uses several on- and off-line wavelengths tuned to the O2 absorption line. The choice of wavelengths allows us to measure the pressure by using two adjacent O2 absorptions in the Oxygen A-band. Our retrieval algorithm fits the O2 lineshapes and derives the pressure. Our measurements compare favorably with a local weather monitor mounted outside our laboratory and a local weather station.

  15. Study of a pressure measurement method using laser ionization for extremely-high vacuum

    International Nuclear Information System (INIS)

    Kokubun, Kiyohide

    1991-01-01

    A method of measuring pressures in the range of extremely-high vacuum (XHV) using the laser ionization has been studied. For this purpose, nonresonant multiphoton ionization of various kinds of gases has been studied, and highly-sensitive ion-detection systems and an extremely-high vacuum equipment were fabricated. These results are presented in detail. Two ion-detection systems were fabricated and tested: the one is based on the pulse-counting method, and the other utilizes the image-processing technique. The former is superior in detecting a few ions or less. The latter was processing technique. The former is superior in detecting a few ions or less. The latter was verified to able to count accurately the number of ions in the range of a few to several hundreds. To obtain the information on residual gases and test our pressure measurement system, an extremely-high vacuum system was fabricated in our own fashion, attained a pressure lower than 1 x 10 -10 Pa, measured with an extractor gauge. The outgassing rate of this vacuum vessel was measured to be 7.8 x 10 -11 Pa·m 3 /s·m 2 . The surface structures and the surface compositions of the raw material, the machined material, and the machined-and-outgased material were studied by SEM and AES. Besides, the pumping characteristics and the residual gases of the XHV system were investigated in detail at each pumping stage. On the course of these studies, the method of pressure measurement using the laser-ionization has been verified to be very effective for measuring pressures in XHV. (J.P.N.)

  16. A Direct inverse model to determine permeability fields from pressure and flow rate measurements

    NARCIS (Netherlands)

    Brouwer, G.K.; Fokker, P.A.; Wilschut, F.; Zijl, W.

    2008-01-01

    The determination of the permeability field from pressure and flow rate measurements in wells is a key problem in reservoir engineering. This paper presents a Double Constraint method for inverse modeling that is an example of direct inverse modeling. The method is used with a standard

  17. ['Authority-based' versus 'evidence-based' blood pressure measurements in pregnancy].

    Science.gov (United States)

    Merkus, J M

    1999-01-23

    Recent evidence suggests that the fifth Korotkoff sound (K5) is a much more reliable point of measurement to determine diastolic blood pressure in pregnant women than the fourth one (K4). The guidelines for obstetricians and midwives should be corrected without delay to reflect this new knowledge. In non-pregnant people K5 already is the point of reference.

  18. Rheological Properties of Extreme Pressure Greases Measured Using a Process Control Rheometer

    DEFF Research Database (Denmark)

    Glasscock, Julie; Smith, Robin S.

    2012-01-01

    A new process control rheometer (PCR) designed for use in industrial process flows has been used to measure the rheological properties of three extreme-pressure greases. The rheometer is a robust yet sensitive instrument designed to operate in an industrial processing environment in either in...

  19. Non-invasive blood pressure measurement in ferrets (Mustela putorius furo) using high definition oscillometry

    NARCIS (Netherlands)

    van Zeeland, Y. R.A.; Wilde, A.; Bosman, I.H.; Uilenreef, J. J.; Egner, B.I.; Schoemaker, N. J.

    2017-01-01

    This study was conducted to validate the use of high definition oscillometry (HDO) for non-invasive blood pressure (NIBP) measurements in ferrets and to establish reference ranges for NIBP in minimally sedated, healthy, young adult ferrets (170 mmHg) conditions. Although HDO correlated well with

  20. From pioneering to implementing automated blood pressure measurement in clinical practice: Thomas Pickering's legacy

    DEFF Research Database (Denmark)

    Stolarz-Skrzypek, Katarzyna; Thijs, Lutgarde; Wizner, Barbara

    2010-01-01

    Thomas G. Pickering spent most of his scientific career in carrying out research on clinical hypertension and blood pressure (BP) measurement. In our review of Pickering's seminal work, we first focused on white-coat hypertension and masked hypertension, two terms that he had introduced. Next, we...

  1. A sound field separation technique based on measurements with pressure-velocity probes

    DEFF Research Database (Denmark)

    Zhang, Yong-Bin; Chen, Xin-Zhao; Jacobsen, Finn

    2009-01-01

    It has recently been shown that statistically optimized near field acoustic holography based on measurement with an array of pressure-velocity transducers makes it possible to distinguish between sources on the two sides of the array and thus suppress the influence of a disturbing source [F...

  2. Genetic influence on blood pressure measured in the office, under laboratory stress and during real life

    NARCIS (Netherlands)

    Wang, Xiaoling; Ding, Xiuhua; Su, Shaoyong; Harshfield, Gregory; Treiber, Frank; Snieder, Harold

    To determine to what extent the genetic influences on blood pressure (BP) measured in the office, under psychologically stressful conditions in the laboratory and during real life are different from each other. Office BP, BP during a video game challenge and a social stressor interview, and 24-h

  3. The measurement of intracranial pressure and brain displacement due to short-duration dynamic overpressure loading

    Science.gov (United States)

    Iwaskiw, A. S.; Ott, K. A.; Armiger, R. S.; Wickwire, A. C.; Alphonse, V. D.; Voo, L. M.; Carneal, C. M.; Merkle, A. C.

    2018-01-01

    The experimental measurement of biomechanical responses that correlate with blast-induced traumatic brain injury (bTBI) has proven challenging. These data are critical for both the development and validation of computational and physical head models, which are used to quantify the biomechanical response to blast as well as to assess fidelity of injury mitigation strategies, such as personal protective equipment. Therefore, foundational postmortem human surrogate (PMHS) experimental data capturing the biomechanical response are necessary for human model development. Prior studies have measured short-duration pressure transmission to the brain (Kinetic phase), but have failed to reproduce and measure the longer-duration inertial loading that can occur (Kinematic phase). Four fully instrumented PMHS were subjected to short-duration dynamic overpressure in front-facing and rear-facing orientations, where intracranial pressure (ICP), global head kinematics, and brain motion (as measured by high-speed X-ray) with respect to the skull were recorded. Peak ICP results generally increased with increased dose, and a mirrored pressure response was seen when comparing the polarity of frontal bone versus occipital bone ICP sensors. The head kinematics were delayed when compared to the pressure response and showed higher peak angles for front-facing tests as compared to rear-facing. Brain displacements were approximately 2-6 mm, and magnitudes did not change appreciably between front- and rear-facing tests. These data will be used to inform and validate models used to assess bTBI.

  4. A new method for measuring the response time of the high pressure ionization chamber

    International Nuclear Information System (INIS)

    Wang, Zhentao; Shen, Yixiong; An, Jigang

    2012-01-01

    Time response is an important performance characteristic for gas-pressurized ionization chambers. To study the time response, it is especially crucial to measure the ion drift time in high pressure ionization chambers. In this paper, a new approach is proposed to study the ion drift time in high pressure ionization chambers. It is carried out with a short-pulsed X-ray source and a high-speed digitizer. The ion drift time in the chamber is then determined from the digitized data. By measuring the ion drift time of a 15 atm xenon testing chamber, the method has been proven to be effective in the time response studies of ionization chambers. - Highlights: ► A method for measuring response time of high pressure ionization chamber is proposed. ► A pulsed X-ray producer and a digital oscilloscope are used in the method. ► The response time of a 15 atm Xenon testing ionization chamber has been measured. ► The method has been proved to be simple, feasible and effective.

  5. Fabrication and characterization of low pressure micro-resistojets with integrated heater and temperature measurement

    NARCIS (Netherlands)

    Cordeiro Guerrieri, D. C.; de Athayde Costa e Silva, Marsil A. C.; van Zeijl, H.W.; Cervone, A.; Gill, E.K.A.

    2017-01-01

    Three low pressure micro-resistojets (LPM) with integrated heater and temperature measurement were designed, manufactured and characterized at Delft university of technology. The devices were manufactured using silicon-based micro electro mechanical systems (MEMS) technology including a heater

  6. Capabilities for measuring physical and chemical properties of rocks at high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Durham, W.B. (comp.)

    1990-01-01

    The Experimental Geophysics Group of the Earth Sciences Department at Lawrence Livermore National Laboratory (LLNL) has experimental equipment that measures a variety of physical properties and phase equilibria and kinetics on rocks and minerals at extreme pressures (to 500 GPa) and temperatures (from 10 to 2800 K). These experimental capabilities are described in this report in terms of published results, photographs, and schematic diagrams.

  7. Pressure pain sensitivity: A new method of stress measurement in patients with ischemic heart disease

    DEFF Research Database (Denmark)

    Bergmann, Natasha; Ballegaard, Søren; Holmager, Pernille

    2013-01-01

    to induce hyperalgesia.The aim of the present study was to evaluate hyperalgesia by pressure pain sensitivity (PPS) in patients with IHD, and compare PPS to questionnaires measuring depressive symptoms, reduced psychological wellbeing, and QOL as markers of stress. Design. A cross-sectional study of 361...

  8. Reliability of in-Shoe Plantar Pressure Measurements in Rheumatoid Arthritis Patients

    Science.gov (United States)

    Vidmar, Gaj; Novak, Primoz

    2009-01-01

    Plantar pressures measurement is a frequently used method in rehabilitation and related research. Metric characteristics of the F-Scan system have been assessed from different standpoints and in different patients, but not its reliability in rheumatoid arthritis patients. Therefore, our objective was to assess reliability of the F-Scan plantar…

  9. Ambulatory heart rate is underestimated when measured by an Ambulatory Blood Pressure device

    NARCIS (Netherlands)

    Vrijkotte, T.G.M.; de Geus, E.J.C.

    1999-01-01

    Objective: To test the validity of ambulatory heart rate (HR) assessment with a cuff ambulatory blood pressure (ABP) monitor. Design: Cross-instrument comparison of HR measured intermittently by a cuff ABP monitor (SpaceLabs, Redmond, Washington, USA), with HR derived from continuous

  10. Ambulatory heart rate is underestimated when measured by an ambulatory blood pressure device

    NARCIS (Netherlands)

    Vrijkotte, T.G.M.; de Geus, E.J.C.

    2001-01-01

    Objective: To test the validity of ambulatory heart rate (HR) assessment with a cuff ambulatory blood pressure (ABP) monitor. Design: Cross-instrument comparison of HR measured intermittently by a cuff ABP monitor (SpaceLabs, Redmond, Washington, USA), with HR derived from continuous

  11. Ambulatory heart rate is underestimated when measured by an ambulatory blood pressure device

    NARCIS (Netherlands)

    Vrijkotte, T. G.; de Geus, E. J.

    2001-01-01

    To test the validity of ambulatory heart rate (HR) assessment with a cuff ambulatory blood pressure (ABP) monitor. Cross-instrument comparison of HR measured intermittently by a cuff ABP monitor (SpaceLabs, Redmond, Washington, USA), with HR derived from continuous electrocardiogram (ECG) recordings

  12. Impact of tire loading and tire pressure on measured 3D contact stresses

    CSIR Research Space (South Africa)

    Hernandez, JA

    2013-06-01

    Full Text Available ) (26.6, 35.5, 44.4, 62.1, and 79.9 kN) and four tire inflation pressures (s0) (552, 690, 758, and 862 kPa). The equipment used for measuring the 3D-contact stresses is described along with the testing procedure and the methodology followed during data...

  13. Use of Repeated Blood Pressure and Cholesterol Measurements to Improve Cardiovascular Disease Risk Prediction

    NARCIS (Netherlands)

    Paige, Ellie; Barrett, Jessica; Pennells, Lisa; Sweeting, Michael; Willeit, Peter; Angelantonio, Di Emanuele; Gudnason, Vilmundur; Nordestgaard, Børge G.; Psaty, Bruce M.; Goldbourt, Uri; Best, Lyle G.; Assmann, Gerd; Salonen, Jukka T.; Nietert, Paul J.; Verschuren, W.M.M.; Brunner, Eric J.; Kronmal, Richard A.; Salomaa, Veikko; Bakker, Stephan L.J.; Dagenais, Gilles R.; Sato, Shinichi; Jansson, Jan Håkan; Willeit, Johann; Onat, Altan; La Cámara, De Agustin Gómez; Roussel, Ronan; Völzke, Henry; Dankner, Rachel; Tipping, Robert W.; Meade, Tom W.; Donfrancesco, Chiara; Kuller, Lewis H.; Peters, Annette; Gallacher, John; Kromhout, Daan; Iso, Hiroyasu; Knuiman, Matthew W.; Casiglia, Edoardo; Kavousi, Maryam; Palmieri, Luigi; Sundström, Johan; Davis, Barry R.; Njølstad, Inger; Couper, David; Danesh, John; Thompson, Simon G.; Wood, Angela M.

    2017-01-01

    The added value of incorporating information from repeated blood pressure and cholesterol measurements to predict cardiovascular disease (CVD) risk has not been rigorously assessed. We used data on 191,445 adults from the Emerging Risk Factors Collaboration (38 cohorts from 17 countries with data

  14. Use of Repeated Blood Pressure and Cholesterol Measurements to Improve Cardiovascular Disease Risk Prediction

    DEFF Research Database (Denmark)

    Paige, Ellie; Barrett, Jessica; Pennells, Lisa

    2017-01-01

    The added value of incorporating information from repeated blood pressure and cholesterol measurements to predict cardiovascular disease (CVD) risk has not been rigorously assessed. We used data on 191,445 adults from the Emerging Risk Factors Collaboration (38 cohorts from 17 countries with data...

  15. Comparing Measures of General and Abdominal Adiposity as Predictors of Blood Pressure in College Students

    Science.gov (United States)

    Abshire, Demetrius A.; Mudd-Martin, Gia; Moser, Debra K.; Lennie, Terry A.

    2018-01-01

    Objective: To compare anthropometric measures of body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR), and sagittal abdominal diameter (SAD) as predictors of blood pressure in college students. Participants: Students (N = 116) were recruited from November 2012 to May 2014 at an urban university and rural community…

  16. In-Situ Pressure Measurements During the Detached Growth of Germanium

    Science.gov (United States)

    Volz, M. P.; Palosz, W.; Szofran, F. R.

    2003-01-01

    Crystal growth by the vertical Bridgman method in which there is little or no contact between the wall and the crystal has been termed detached solidification. Detachment has been observed frequently in previous microgravity experiments, and has been reported under some terrestrial conditions as well. It is expected that detachment can be conditioned by establishing an appropriate pressure difference below and above the melt. To test this hypothesis, an experimental technique has been developed to measure this pressure difference during the growth of germanium by the vertical Bridgman method. The apparatus allows for both monitoring the pressures and actively controlling them during growth. For a given melt height, there is a maximum pressure difference attainable before gas bubbles up through the melt. This maximum pressure increases with increasing melt height. As the melt height approaches zero, the maximum pressure difference, about 20 mbar in these experiments, is determined by the surface tension and gap width of the meniscus at the bottom of the melt.

  17. Hydrogen equilibrium pressure measurements in the Li-N-H system by static manometric method

    International Nuclear Information System (INIS)

    Ananda, N.S.; Jat, R.A.; Sawant, S.G.; Parida, S.C.; Singh, Z.; Venugopal, V.

    2010-01-01

    Light weight hydrogen storage materials are very promising in terms of their high gravimetric hydrogen storage capacity and low cost. One such reported system is the Li-N-H system with a theoretical hydrogen capacity of 11.5 wt% according to the following equilibrium reactions; (1) Li 3 N+H 2 → Li 2 NH + LiH and (2) Li 2 NH+H 2 → LiNH 2 + LiH. The enthalpy of reaction (1) is -165 kJ/mole of H 2 whereas that of reaction (2) is -45 kJ/mole of H 2 . Hence, the second reaction is of utmost importance for low temperature release of hydrogen with a capacity of 6.5 wt%. The equilibrium hydrogen pressures of the above two reactions have been reported by pressure-composition isotherm studies at a pressure range of 3-15 atm., in which the mid-point of the sloping plateau of P-C isotherm is considered as the equilibrium pressure. This method may not yield the true equilibrium pressure. Hence, in this study, we have carried out measurements of equilibrium pressure using a static manometric method where we have considered reaction (2) only

  18. Ares I Scale Model Acoustic Tests Instrumentation for Acoustic and Pressure Measurements

    Science.gov (United States)

    Vargas, Magda B.; Counter, Douglas D.

    2011-01-01

    The Ares I Scale Model Acoustic Test (ASMAT) was a development test performed at the Marshall Space Flight Center (MSFC) East Test Area (ETA) Test Stand 116. The test article included a 5% scale Ares I vehicle model and tower mounted on the Mobile Launcher. Acoustic and pressure data were measured by approximately 200 instruments located throughout the test article. There were four primary ASMAT instrument suites: ignition overpressure (IOP), lift-off acoustics (LOA), ground acoustics (GA), and spatial correlation (SC). Each instrumentation suite incorporated different sensor models which were selected based upon measurement requirements. These requirements included the type of measurement, exposure to the environment, instrumentation check-outs and data acquisition. The sensors were attached to the test article using different mounts and brackets dependent upon the location of the sensor. This presentation addresses the observed effect of the sensors and mounts on the acoustic and pressure measurements.

  19. Ares I Scale Model Acoustic Test Instrumentation for Acoustic and Pressure Measurements

    Science.gov (United States)

    Vargas, Magda B.; Counter, Douglas

    2011-01-01

    Ares I Scale Model Acoustic Test (ASMAT) is a 5% scale model test of the Ares I vehicle, launch pad and support structures conducted at MSFC to verify acoustic and ignition environments and evaluate water suppression systems Test design considerations 5% measurements must be scaled to full scale requiring high frequency measurements Users had different frequencies of interest Acoustics: 200 - 2,000 Hz full scale equals 4,000 - 40,000 Hz model scale Ignition Transient: 0 - 100 Hz full scale equals 0 - 2,000 Hz model scale Environment exposure Weather exposure: heat, humidity, thunderstorms, rain, cold and snow Test environments: Plume impingement heat and pressure, and water deluge impingement Several types of sensors were used to measure the environments Different instrument mounts were used according to the location and exposure to the environment This presentation addresses the observed effects of the selected sensors and mount design on the acoustic and pressure measurements

  20. Measurement of electron density in the atmospheric pressure helium plasma jet by using a dielectric probe

    International Nuclear Information System (INIS)

    Qi Bing; Zhou Qiujiao; Pan Lizhu; Zhang Mengdie; Huang Jianjun

    2014-01-01

    The electron densities in the atmospheric pressure helium plasma were calculated by means of electron drift velocity and the jet velocity respectively. The electron velocity and jet velocity can be calculated by means of helium plasma jet current measured by a dielectric probe and plasma discharge current signal measured by voltage probes. The results show that the estimated electron densities of the helium plasma jet calculated from electron drift velocity and the jet velocity are in the order of 10 11 cm -3 and they increase with applied voltage. There is a little fluctuation in the value of the electron density along the jet axis of the plasma. This result is the same as the measured electron density in atmospheric pressure helium non-thermal plasma jet by using a Rogowski coil and a Langmuir probe. This is in one order lower than the electron density measured by microwave antenna. (authors)

  1. A new transducer for local load measurements of friction and roll pressure in cold flat rolling

    DEFF Research Database (Denmark)

    Lagergren, J.; Wanheim, Tarras; Precz, W.

    2006-01-01

    The only way to establish the true rolling pressure and the true friction condition in cold rolling is to conduct measurements in the roll bite. A new transducer design is therefore proposed, in order to overcome problems in previous measurements in the past 70 years. The new idea is to increase...... the contact surface of the transducer, to be larger than the arc of contact. This is in contrast to the smaller and smaller contact pin design that has been prevailing. The measurements were conducted during cold dry rolling of both copper strips and stainless steel strips in a pilot mill. The recordings were...... selected from a steady state with no disturbance from the material flow. The transducer was able to simultaneously measure both the normal pressure and the friction stress. An estimation of the coefficient of friction was accordingly performed. The new transducer works very well, it was seen to be robust...

  2. Blood pressure measurement of all five fingers by strain gauge plethysmography

    DEFF Research Database (Denmark)

    Hirai, M; Nielsen, S L; Lassen, N A

    1976-01-01

    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 the other fingers was measured using a 24-mm-wide cuff. Blood pressure at the proximal phalanx was higher than that at the intermediate phalanx in all fingers except finger V. The difference of blood pressure values corresponded well with circumference of the finger. In 15 normal subjects, blood pressure...... of the mean values was larter with the 27-mm-wide cuff than with the 24-mm-wide cuff, the 24-mm-wide cuff was considered to be most suitable for clinical use in fingers I, II, III, and IV. By using the 20-mm-wide cuff in finger V and the 24-mm-wide cuff in the other fingers, normal value of finger blood...

  3. The quantitative evaluation of intracranial pressure by optic nerve sheath diameter/eye diameter CT measurement.

    Science.gov (United States)

    Bekerman, Inessa; Sigal, Tal; Kimiagar, Itzhak; Ben Ely, Anna; Vaiman, Michael

    2016-12-01

    The changes of the optic nerve sheath diameter (ONSD) have been used to assess changes of the intracranial pressure for 20 years. The aim of this research was to further quantify the technique of measuring the ONSD for this purpose. Retrospective study of computed tomographic (CT) data of 1766 adult patients with intracranial hypotension (n=134) or hypertension (n=1632) were analyzed. The eyeball transverse diameter (ETD) and ONSD were obtained bilaterally, and the ONSD/ETD ratio was calculated. The ratio was used to calculate the normal ONSD for patients and to estimate the intracranial pressure of the patients before and after the onset of the pathology. Correlation analysis was performed with invasively measured intracranial pressure, the presence or absence of papilledema, sex, and age. In hypotension cases, the ONSD by CT was 3.4±0.7 mm (P=.03 against normative 4.4±0.8 mm). In cases with hypertension, the diameter was 6.9±1.3 (P=.02, with a cutoff value ˃5.5 mm). The ONSD/ETD ratio was 0.29±0.04 against 0.19±0.02 in healthy adults (P=.01). The ONSD and the ONSD/ETD ratio can indicate low intracranial pressure, but quantification is impossible at intracranial pressure less than 13 mm Hg. In elevated intracranial pressure, the ONSD and the ratio provide readings that correspond to readings in millimeters of mercury. The ONSD method, reinforced with additional calculations, may help to indicate a raised intracranial pressure, evaluate its severity quantitatively, and establish quantitative goals for treatment of intracranial hypertension, but the limitations of the method are to be taken into account. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Non-invasive blood pressure measurement in ferrets (Mustela putorius furo) using high definition oscillometry

    OpenAIRE

    van Zeeland, Y. R.A.; Wilde, A.; Bosman, I.H.; Uilenreef, J. J.; Egner, B.I.; Schoemaker, N. J.

    2017-01-01

    This study was conducted to validate the use of high definition oscillometry (HDO) for non-invasive blood pressure (NIBP) measurements in ferrets and to establish reference ranges for NIBP in minimally sedated, healthy, young adult ferrets (170 mmHg) conditions. Although HDO correlated well with DABP (r > 0.90), it showed significant proportional bias, whereby HDO generally underestimated DABP with hyper- and normotensive conditions, and overestimated DABP with hypotensive conditions. Measure...

  5. Validating and Calibrating the Nintendo Wii Balance Board to Derive Reliable Center of Pressure Measures

    OpenAIRE

    Leach, Julia; Mancini, Martina; Peterka, Robert; Hayes, Tamara; Horak, Fay

    2014-01-01

    The Nintendo Wii balance board (WBB) has generated significant interest in its application as a postural control measurement device in both the clinical and (basic, clinical, and rehabilitation) research domains. Although the WBB has been proposed as an alternative to the “gold standard” laboratory-grade force plate, additional research is necessary before the WBB can be considered a valid and reliable center of pressure (CoP) measurement device. In this study, we used the WBB and a laborator...

  6. Calculation of the internal pressure of fuel rod from measurements of krypton-85 at its plenum

    International Nuclear Information System (INIS)

    Arana, I.; Doncel, N.; Casado, C.

    2012-01-01

    ENUSA carried out numerous campaigns of measurement internal pressure of fuel rod irradiated. All of them have been performed of form destructively in a hot cell laboratory which implies a time high to obtain results and a high economic cost to obtain a single data by rod, representative of the end of the irradiation. The objective of the project is to develop a non-destructive measurement and a methodology for reliable calculation that eliminates these problems.

  7. Electric field measurements at near-atmospheric pressure by coherent Raman scattering of laser beams

    International Nuclear Information System (INIS)

    Ito, Tsuyohito; Kobayashi, Kazunobu; Hamaguchi, Satoshi; Mueller, Sarah; Czarnetzki, Uwe

    2010-01-01

    Electric field measurements at near-atmospheric pressure environments based on electric-field induced Raman scattering are applied to repetitively pulsed nanosecond discharges. The results have revealed that the peak electric field near the centre of the gap is almost independent of the applied voltage. Minimum sustainable voltage measurements suggests that, at each discharge pulse, charged particles that remain from the previous pulse serve as discharge seeds and play an important role for generation of uniform glow-like discharges.

  8. Reliability and responsiveness of algometry for measuring pressure pain threshold in patients with knee osteoarthritis

    OpenAIRE

    Mutlu, Ebru Kaya; Ozdincler, Arzu Razak

    2015-01-01

    [Purpose] This study aimed to establish the intrarater reliability and responsiveness of a clinically available algometer in patients with knee osteoarthritis as well as to determine the minimum-detectable-change and standard error of measurement of testing to facilitate clinical interpretation of temporal changes. [Subjects] Seventy-three patients with knee osteoarthritis were included. [Methods] Pressure pain threshold measured by algometry was evaluated 3 times at 2-min intervals over 2 cl...

  9. Electronic energy gap of molecular hydrogen from electrical conductivity measurements at high shock pressures

    Science.gov (United States)

    Nellis, W. J.; Mitchell, A. C.; Mccandless, P. C.; Erskine, D. J.; Weir, S. T.

    1992-01-01

    Electrical conductivities were measured for liquid D2 and H2 shock compressed to pressures of 10-20 GPa (100-200 kbar), molar volumes near 8 cu cm/mol, and calculated temperatures of 2900-4600 K. The semiconducting energy gap derived from the conductivities is 12 eV, in good agreement with recent quasi-particle calculations and with oscillator frequencies measured in diamond-anvil cells.

  10. Note: Molecular diffusivity in a small pore zeolite measured by a variable pressure (piezometric) uptake method.

    Science.gov (United States)

    Wang, Fei; Kobayashi, Yasukazu; Muhammad, Usman; Wang, Dezheng; Wang, Yao

    2016-03-01

    The use of numerical analysis to solve the diffusion equation in the uptake method allowed the measurement of molecular diffusivity in a zeolite with a variable pressure around it. The diffusivity was obtained from the data in the measurement of the adsorption isotherm, which means that the diffusivity measurement now needs neither a special instrument nor procedure. The diffusivities of all the gases are readily available from the measurement of their adsorption isotherms and these data include how the diffusivity changes versus adsorbed concentration. The modeling introduced can also be used for a zeolite with a surface barrier.

  11. Gravity reduction with three-dimensional atmospheric pressure data for precise ground gravity measurements

    Science.gov (United States)

    Neumeyer, Juergen; Hagedoorn, Jan; Leitloff, Jens; Schmidt, Torsten

    2004-10-01

    The redistribution of air masses induces gravity variations (atmospheric pressure effect) up to about 20 μgal. These variations are disturbing signals in gravity records and they must be removed very carefully for detecting weak gravity signals. In the past, different methods have been developed for modelling of the atmospheric pressure effect. These methods use local or two-dimensional (2D) surface atmospheric pressure data and a standard height-dependent air density distribution. The atmospheric pressure effect is consisting of the elastic deformation and attraction term. The deformation term can be well modelled with 2D surface atmospheric pressure data, for instance with the Green's function method. For modelling of the attraction term, three-dimensional (3D) data are required. Results with 2D data are insufficient. From European Centre for Medium-Range Weather Forecasts (ECMWF) 3D atmospheric pressure data are now available. The ECMWF data used here are characterised by a spacing of Δ ϕ and Δ λ = 0.5°, 60 pressure levels up to a height of 60 km and an interval of 6 h. These data are used for modelling of the atmospheric attraction term. Two attraction models have been developed based on the point mass attraction of air segments and the gravity potential of the air masses. The modelling shows a surface pressure-independent part of gravity variations induced by mass redistribution of the atmosphere in the order of some μgal. This part can only be determined by using 3D atmospheric pressure data. It has been calculated for the Vienna Superconducting Gravimeter site. From this follows that the gravity reduction can be improved by applying the 3D atmospheric attraction model for analysing long-periodic tidal waves including the polar tide. The same improvement is expected for reduction of long-term absolute gravity measurements or comparison of gravity measurements at different seasonal times. By using 3D atmospheric pressure data, the gravity correction can

  12. Doppler ultrasound compared with strain gauge for measurement of systolic ankle blood pressure.

    Science.gov (United States)

    Joensen, J B; Juul, S; Abrahamsen, J; Henneberg, E W; Lindholt, Jes S

    2008-01-01

    This study assesses measurement variation in the measurement of ankle systolic blood pressure (ABP) when measured with Doppler ultrasound and with the strain gauge method. Ninety-seven patients were included. ABP was measured with Doppler ultrasound and with the strain gauge method. The methods were compared graphically by scatterplots and analyzed by paired t test, analysis of variance, and Pitman's paired variance ratio test. ABP was measured by strain gauge in all extremities, whereas no Doppler signal was obtainable in 7 limbs (4%). There was no systematic difference in measurements between the means of the two measurements. However, a substantial difference of more than 25 mm Hg was found in 15% of limbs and more than 20 mm Hg in 20%. In the majority of patients, measurements of ABP by Doppler ultrasound and the strain gauge method give similar results, but for a minority the discrepancy is substantial.

  13. Shock tunnel measurements of surface pressures in shock induced separated flow field using MEMS sensor array

    International Nuclear Information System (INIS)

    Sriram, R; Jagadeesh, G; Ram, S N; Hegde, G M; Nayak, M M

    2015-01-01

    Characterized not just by high Mach numbers, but also high flow total enthalpies—often accompanied by dissociation and ionization of flowing gas itself—the experimental simulation of hypersonic flows requires impulse facilities like shock tunnels. However, shock tunnel simulation imposes challenges and restrictions on the flow diagnostics, not just because of the possible extreme flow conditions, but also the short run times—typically around 1 ms. The development, calibration and application of fast response MEMS sensors for surface pressure measurements in IISc hypersonic shock tunnel HST-2, with a typical test time of 600 μs, for the complex flow field of strong (impinging) shock boundary layer interaction with separation close to the leading edge, is delineated in this paper. For Mach numbers 5.96 (total enthalpy 1.3 MJ kg −1 ) and 8.67 (total enthalpy 1.6 MJ kg −1 ), surface pressures ranging from around 200 Pa to 50 000 Pa, in various regions of the flow field, are measured using the MEMS sensors. The measurements are found to compare well with the measurements using commercial sensors. It was possible to resolve important regions of the flow field involving significant spatial gradients of pressure, with a resolution of 5 data points within 12 mm in each MEMS array, which cannot be achieved with the other commercial sensors. In particular, MEMS sensors enabled the measurement of separation pressure (at Mach 8.67) near the leading edge and the sharply varying pressure in the reattachment zone. (paper)

  14. Can we trust intraocular pressure measurements in eyes with intracameral air?

    Science.gov (United States)

    Jóhannesson, Gauti; Lindén, Christina; Eklund, Anders; Behndig, Anders; Hallberg, Per

    2014-10-01

    To evaluate the effect of intracameral air on intraocular pressure (IOP) measurements using Goldmann applanation tonometry (GAT) and applanation resonance tonometry (ART) in an in-vitro porcine eye model. IOP was measured on thirteen freshly enucleated eyes at three reference pressures: 20, 30, and 40 mmHg. Six measurements/method were performed in a standardized order with GAT and ART respectively. Air was injected intracamerally in the same manner as during Descemet's stripping endothelial keratoplasty (DSEK) and Descemet's membrane endothelial keratoplasty (DMEK), and the measurements were repeated. Measured IOP increased significantly for both tonometry methods after air injection: 0.7 ± 2.1 mmHg for GAT and 10.6 ± 4.9 mmHg for ART. This difference was significant at each reference pressure for ART but not for GAT. Although slightly affected, this study suggests that we can trust GAT IOP-measurements in eyes with intracameral air, such as after DSEK/DMEK operations. Ultrasound-based methods such as ART should not be used.

  15. Reliability and responsiveness of algometry for measuring pressure pain threshold in patients with knee osteoarthritis.

    Science.gov (United States)

    Mutlu, Ebru Kaya; Ozdincler, Arzu Razak

    2015-06-01

    [Purpose] This study aimed to establish the intrarater reliability and responsiveness of a clinically available algometer in patients with knee osteoarthritis as well as to determine the minimum-detectable-change and standard error of measurement of testing to facilitate clinical interpretation of temporal changes. [Subjects] Seventy-three patients with knee osteoarthritis were included. [Methods] Pressure pain threshold measured by algometry was evaluated 3 times at 2-min intervals over 2 clinically relevant sites-mediolateral to the medial femoral tubercle (distal) and lateral to the medial malleolus (local)-on the same day. Intrarater reliability was estimated by intraclass correlation coefficients. The minimum-detectable-change and standard error of measurement were calculated. As a measure of responsiveness, the effect size was calculated for the results at baseline and after treatment. [Results] The intrarater reliability was almost perfect (intraclass correlation coefficient = 0.93-0.97). The standard error of measurement and minimum-detectable-change were 0.70-0.66 and 1.62-1.53, respectively. The pressure pain threshold over the distal site was inadequately responsive in knee osteoarthritis, but the local site was responsive. The effect size was 0.70. [Conclusion] Algometry is reliable and responsive to assess measures of pressure pain threshold for evaluating pain patients with knee osteoarthritis.

  16. Cuffed endotracheal tubes in infants and children: a technique to continuously measure the intracuff pressure.

    Science.gov (United States)

    Gopalakrishnan, Senthil; Barry, N'Diris; Rice, Julie; Tobias, Joseph D

    2013-07-01

    Various devices have been used to measure the intracuff pressure (CP) of an endotracheal tube at the time of inflation; however, no device has found widespread acceptance for the continuous monitoring of CP. We devised a simple method to continuously measure the CP using an invasive pressure monitoring setup (IPMS), which is used routinely in the operating room to monitor arterial or central venous pressures. The accuracy of the device was compared to those obtained from a commercially available and clinically used manometer (MM). Size 4.0, 5.0 and 6.0 mm ID cETTs were placed into one of 3 sizes of polyvinylchloride (PVC) tubes. The cuff of the cETT was inflated after inserting the cETT into the PVC pipes. After inflation, the CP was simultaneously checked using the MM and the IPMS. A total of 100 simultaneous (IPMS and MM) readings were obtained from each of the 3 sizes of cETT with the intracuff pressure randomly varying between 10 and 40 cmH₂O. Statistical analysis included a Bland-Altman comparison to determine the bias, mean, and 95% levels of agreement (LOA), and a linear regression analysis. Linear regression analysis demonstrated an R(2) value of 0.988, 0.9899, and 0.9879 when comparing the pressure from the IPMS and MM from the 4.0, 5.0 and 6.0 mm cETT, respectively. A standard IPMS can be used to continuously monitor intracuff pressure with the use of a cETT. Although various techniques can be used safely to avoid hyperinflation of the cuff, they provide only an instantaneous measure of the CP. The current technique allows for continuous monitoring of CP during prolonged cases or in other clinical scenarios when such monitoring is required. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  17. Prevalence of high blood pressure measured in the Brazilian population, National Health Survey, 2013.

    Science.gov (United States)

    Malta, Deborah Carvalho; Santos, Nadir Baltazar Dos; Perillo, Rosângela Durso; Szwarcwald, Célia Landmann

    2016-04-01

    High blood pressure (hypertension) is the most frequent cause of morbidity and a major risk factor for cardiovascular complications. The aim here was to describe the prevalence of blood pressure greater than or equal to 140/90 mmHg in the adult Brazilian population and federal states, along with self-reported information about previous medical diagnoses of hypertension, use of medication and medical care for hypertension control. Cross-sectional study analyzing information from the National Health Survey of 2013, relating to Brazil and its federal states. The sample size was estimated as 81,254 households and information was collected from 64,348 households. The survey consisted of interviews, physical and laboratory measurements. Systolic blood pressure was considered to be high when it was ≥ 140 mmHg and diastolic blood pressure, ≥ 90 mmHg. It was found that 22.8% of the population has blood pressure measurements ≥ 140/90 mmHg. The proportion was higher among men than among women: 25.8% versus 20.0%. The frequency increased with age, reaching 47.1% in individuals over 75 years and was highest in the southeast and south. 43.2% reported previous medical diagnoses of hypertension and, of these, 81.4% reported using medication for hypertension and 69.6%, going to the doctor within the past year for pressure monitoring, thus showing regular medical follow-up. These results are important for supporting measures for preventing and treating hypertension in Brazil, with the aim of achieving the World Health Organization's goal of reducing hypertension by 25% over the next decade.

  18. Pressure sound level measurements at an educational environment in Goiania, Goias, Brazil

    International Nuclear Information System (INIS)

    Costa, Jhonatha J.L.; Nascimento, Eriberto O. do; Oliveira, Lucas N. de; Caldas, Linda V. E.

    2017-01-01

    In this work, twenty five points located on the ground floor of the Federal Institute of Education, Science and Technology of Goias - IFG - Campus Goiania, were analyzed in morning periods of two Saturdays. The pressure sound levels were measured at internal and external environments during routine activities seeking to perform an environmental monitoring at this institution. The initial hypothesis was that an amusement park (Mutirama Park) was responsible for originating noise pollution in the institution, but the results showed, within the campus environment, sound pressure levels in accordance with the Municipal legislation of Goiania for all points. (author)

  19. A simple, reliable, and no-destructive method for the measurement of vacuum pressure

    OpenAIRE

    Yuan, Jinpeng; Ji, Zhonghua; Zhao, Yanting; Chang, Xuefang; Xiao, Liantuan; Jia, Suotang

    2013-01-01

    We present a simple, reliable, and no-destructive method for the measurement of vacuum pressure in a magneto-optical trap. The vacuum pressure is verified to be proportional to collision rate constant between cold atoms and background gas with a coefficient k, which can be calculated by simple ideal gas law. The rate constant for loss due to collisions with all background gases can be derived from the total collision loss rate by a series of loading curve of cold atoms under different trappin...

  20. Simple, reliable, and nondestructive method for the measurement of vacuum pressure without specialized equipment.

    Science.gov (United States)

    Yuan, Jin-Peng; Ji, Zhong-Hua; Zhao, Yan-Ting; Chang, Xue-Fang; Xiao, Lian-Tuan; Jia, Suo-Tang

    2013-09-01

    We present a simple, reliable, and nondestructive method for the measurement of vacuum pressure in a magneto-optical trap. The vacuum pressure is verified to be proportional to the collision rate constant between cold atoms and the background gas with a coefficient k, which can be calculated by means of the simple ideal gas law. The rate constant for loss due to collisions with all background gases can be derived from the total collision loss rate by a series of loading curves of cold atoms under different trapping laser intensities. The presented method is also applicable for other cold atomic systems and meets the miniaturization requirement of commercial applications.

  1. Optical measurements on hydrogen at ultrahigh static pressures. Summary report for NRIP W233

    International Nuclear Information System (INIS)

    Mills, R.L.; Liebenberg, D.H.

    1979-02-01

    The results of a two-year New Research Initiatives Program (NRIP) aimed at developing apparatus and techniques for studying hydrogen and other gases under ultrahigh static pressure in diamond--anvil cells are summarized. The following goals were achieved: A facility was established in which precision optical measurements can be made; special diamond cells for use at low temperatures were built; procedures were devised for loading cells with gases at high density; preliminary visual, x-ray, and spectral studies on various gases at pressures up to 50 kbar were conducted; and having demonstrated the feasibility of NRIP, other sponsorship on a continuing basis was obtained

  2. Instrumenting a pressure suppression experiment for a Mark I boiling water reactor: another measurements engineering challenge

    International Nuclear Information System (INIS)

    Shay, W.M.; Brough, W.G.; Miller, T.B.

    1978-01-01

    A 1 / 5 -scale test facility of a pressure-suppression system from a Mark I boiling water reactor was instrumented with seven types of transducers to obtain high-accuracy, dynamic loading data during a hypothetical loss-of-coolant accident. A total of 27 air tests have been completed with an average of 175 transducers recorded for each test. An end-to-end calibration of the total measurement system was run to establish accuracy of the data. The instrumentation verified the analysis of the dynamic loading of the pressure-suppression system

  3. Differences in blood pressure by measurement technique in neurocritically ill patients: A technological assessment.

    Science.gov (United States)

    Lele, Abhijit V; Wilson, Daren; Chalise, Prabhakar; Nazzaro, Jules; Krishnamoorthy, Vijay; Vavilala, Monica S

    2018-01-01

    Blood pressure data may vary by measurement technique. We performed a technological assessment of differences in blood pressure measurement between non-invasive blood pressure (NIBP) and invasive arterial blood pressure (ABP) in neurocritically ill patients. After IRB approval, a prospective observational study was performed to study differences in systolic blood pressure (SBP), mean arterial pressure (MAP), and cerebral perfusion pressure (CPP) values measured by NIBP arm, ABP at level of the phlebostatic axis (ABP heart) and ABP at level of the external auditory meatus (ABP brain) at 30 and 45-degree head of bed elevation (HOB) using repeated measure analysis of covariance and correlation coefficients. Overall, 168 patients were studied with median age of 57 ± 15 years, were mostly female (57%), with body mass index ≤30 (66%). Twenty-three percent (n = 39) had indwelling intracranial pressure monitors, and 19.7% (n = 33) received vasoactive agents. ABP heart overestimated ABP brain for SBP (11.5 ± 2.7 mmHg, p < .001), MAP (mean difference 13.3 ± 0.5 mmHg, p < .001) and CPP (13.4 ± 3.2 mmHg, p < .001). ABP heart overestimated NIBP arm for SBP (8 ± 1.5 mmHg, p < .001), MAP (mean difference 8.6 ± 0.8 mmHg, p < .001), and CPP (mean difference 9.8 ± 3.2 mmHg, p < .001). Regardless of HOB elevation, ABP heart overestimates MAP compared to ABP brain and NIBP arm. Using ABP heart data overestimates CPP and may be responsible for not achieving SBP, MAP or CPP targets aimed at the brain. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Identification of heart disease-prone personality using oscillometric blood pressure measurements.

    Science.gov (United States)

    Jung, Seungah; Shin, Youngsuk

    2015-01-01

    By using the conventional method of measuring two-points (systolic and diastolic) blood pressure, it is difficult to differentiate a heart disease-prone personality from normals. Recently, an oscillometric method that reflects the personalized trait of blood pressure was developed by one author. By using this new measurement technique, this study intended to test the possibility of differentiating a heart disease-prone personality (type A or type D) from normal people. TPA scale in MMPI-2 and DS14 were used for screening type A and D. Oscillometric waveforms created by the cuff pressure were segmented into window blocks based on a single beat at a minimum, allowing this method to extract maximal top and bottom amplitudes in each window block. Then, a spectrogram using a short-time Fourier transform was applied to discriminate between character types in extracted blood pressure patterns with linear discriminant analysis. Compared to a normal personality, type A and type D personalities displayed a lower frequency response on STFT with maximum negative amplitudes than normals. In particular, the type D personality showed a lower frequency response than the type A personality. These results could provide a new qualitative method for measuring different biological indices between type A or D personalities and normals.

  5. Electrochemical cell and electrode designs for high-temperature/high-pressure kinetic measurements

    International Nuclear Information System (INIS)

    Nagy, Z.; Yonco, R.M.

    1987-05-01

    Many corrosion processes of interest to the nuclear power industry occur in high-temperature/high-pressure aqueous systems. The investigation of the kinetics of the appropriate electrode reactions is a serious experimental challenge, partially because of the high temperatures and pressures and partially because many of these reactions are very rapid, requiring fast relaxation measurements. An electrochemical measuring system is described which is suitable for measurements of the kinetics of fast electrode reactions at temperatures extending to at least 300 0 C and pressures to at least 10 MPa (100 atmospheres). The system includes solution preparation and handling equipment, the electrochemical cell, and several electrode designs. One of the new designs is a coaxial working electrode-counter electrode assembly; this electrode can be used with very fast-rising pulses, and it provides a well defined, repeatedly-polishable working surface. Low-impedance reference electrodes are also described, based on electrode concepts responding to the pH or the redox potential of the test solution. Additionally, a novel, long-life primary reference electrode design is reported, based on a modification of the external, pressure-balanced Ag/AgCl reference electrode

  6. Wall pressure measurements of flooding in vertical countercurrent annular air–water flow

    Energy Technology Data Exchange (ETDEWEB)

    Choutapalli, I., Vierow, K.

    2010-01-01

    An experimental study of flooding in countercurrent air-water annular flow in a large diameter vertical tube using wall pressure measurements is described in this paper. Axial pressure profiles along the length of the test section were measured up to and after flooding using fast response pressure transducers for three representative liquid flow rates representing a wide range of liquid Reynolds numbers (ReL = 4Γ/μ; Γ is the liquid mass flow rate per unit perimeter; μ is the dynamic viscosity) from 3341 to 19,048. The results show that flooding in large diameter tubes cannot be initiated near the air outlet and is only initiated near the air inlet. Fourier analysis of the wall pressure measurements shows that up to the point of flooding, there is no dominant wave frequency but rather a band of frequencies encompassing both the low frequency and the broad band that are responsible for flooding. The data indicates that flooding in large diameter vertical tubes may be caused by the constructive superposition of a plurality of waves rather than the action of a single large-amplitude wave.

  7. Measurements of Sound Velocity of Diamond at the Pressure Around the Melt

    Science.gov (United States)

    Shigemori, K.; Shimizu, K.; Asakura, Y.; Hayashi, D.; Nakamoto, Y.; Kagayama, T.; Sakaiya, T.; Kondo, T.; Sumiya, H.; Irifune, T.; Kurosawa, K.; Sugita, S.; Kadono, T.; Hironaka, Y.

    2011-10-01

    We have measured the sound velocity of the diamond foils at around the melting pressures (500 - 1500 GPa). Experiments were done on GEKKO-XII glass laser system with HIPER irradiation facility. Single crystal diamond foils (Ia) of 30 ~40 μm thickness were irradiated at intensities of 0.2 - 1.5 × 1014 W/cm2. We measured the sound velocity by side-on x-ray backlighting technique. Trajectories of foil surfaces were observed by x-ray streak camera. We also measured the shock velocity by two VISARs (velocity interferometer system for any reflector), and shocked temperature by an SOP (streaked optical pyrometer) in order to determine the pressure and the temperature at around the melting. Experimental data were compared with the previous theoretical studies and the percolation theory.

  8. Solubility Measurements and Modeling of Zinc, Lead and Iron Sulfides at High Temperatures and High Pressures

    DEFF Research Database (Denmark)

    Carolina Figueroa Murcia, Diana; Fosbøl, Philip Loldrup; Thomsen, Kaj

    Solubility measurements of sulfides in aqueous solutions are necessary to understand the behaviour of these scaling minerals in geothermal and oil reservoirs. The low solubility levels of Zinc Sulfide (ZnS), Lead Sulfide (PbS) and Iron Sulfide (FeS) make the solubility measurements a challenging...... task. Consequently existing data are rare and scattered. The aim of this work is to develop a reliable experimental procedure and to measure solubility of sulfides at high temperature and pressures. Additionally the experimental data are used for estimation of the solid-liquid equilibrium using...... the Extended UNIQUAC model. The experimental determination of the solubility of ZnS, PbS and FeS is carried out at temperatures up to 200°C and pressures up to 60 bars. The minerals in their pure form are added to ultra-pure water previously degassed with nitrogen. The aqueous solution is prepared in a reduced...

  9. Cuff-less blood pressure measurement using pulse arrival time and a Kalman filter

    International Nuclear Information System (INIS)

    Zhang, Qiang; Chen, Xianxiang; Fang, Zhen; Xue, Yongjiao; Xia, Shanhong; Zhan, Qingyuan; Yang, Ting

    2017-01-01

    The present study designs an algorithm to increase the accuracy of continuous blood pressure (BP) estimation. Pulse arrival time (PAT) has been widely used for continuous BP estimation. However, because of motion artifact and physiological activities, PAT-based methods are often troubled with low BP estimation accuracy. This paper used a signal quality modified Kalman filter to track blood pressure changes. A Kalman filter guarantees that BP estimation value is optimal in the sense of minimizing the mean square error. We propose a joint signal quality indice to adjust the measurement noise covariance, pushing the Kalman filter to weigh more heavily on measurements from cleaner data. Twenty 2 h physiological data segments selected from the MIMIC II database were used to evaluate the performance. Compared with straightforward use of the PAT-based linear regression model, the proposed model achieved higher measurement accuracy. Due to low computation complexity, the proposed algorithm can be easily transplanted into wearable sensor devices. (paper)

  10. Cuff-less blood pressure measurement using pulse arrival time and a Kalman filter

    Science.gov (United States)

    Zhang, Qiang; Chen, Xianxiang; Fang, Zhen; Xue, Yongjiao; Zhan, Qingyuan; Yang, Ting; Xia, Shanhong

    2017-02-01

    The present study designs an algorithm to increase the accuracy of continuous blood pressure (BP) estimation. Pulse arrival time (PAT) has been widely used for continuous BP estimation. However, because of motion artifact and physiological activities, PAT-based methods are often troubled with low BP estimation accuracy. This paper used a signal quality modified Kalman filter to track blood pressure changes. A Kalman filter guarantees that BP estimation value is optimal in the sense of minimizing the mean square error. We propose a joint signal quality indice to adjust the measurement noise covariance, pushing the Kalman filter to weigh more heavily on measurements from cleaner data. Twenty 2 h physiological data segments selected from the MIMIC II database were used to evaluate the performance. Compared with straightforward use of the PAT-based linear regression model, the proposed model achieved higher measurement accuracy. Due to low computation complexity, the proposed algorithm can be easily transplanted into wearable sensor devices.

  11. Resonant tube for measurement of sound absorption in gases at low frequency/pressure ratios

    Science.gov (United States)

    Zuckerwar, A. J.; Griffin, W. A.

    1980-01-01

    The paper describes a resonant tube for measuring sound absorption in gases, with specific emphasis on the vibrational relaxation peak of N2, over a range of frequency/pressure ratios from 0.1 to 2500 Hz/atm. The experimental background losses measured in argon agree with the theoretical wall losses except at few isolated frequencies. Rigid cavity terminations, external excitation, and a differential technique of background evaluation were used to minimize spurious contributions to the background losses. Room temperature measurements of sound absorption in binary mixtures of N2-CO2 in which both components are excitable resulted in the maximum frequency/pressure ratio in Hz/atm of 0.063 + 123m for the N2 vibrational relaxation peak, where m is mole percent of added CO2; the maximum ratio for the CO2 peak was 34,500 268m where m is mole percent of added N2.

  12. DRUGAS: implantable telemetric system for measuring the portal venous pressure: assembly aspects

    Directory of Open Access Journals (Sweden)

    Fischer Roland

    2017-09-01

    Full Text Available Developing an implantable, telemetric pressure measuring system for venous applications makes a high degree of miniaturization necessary. Thus the influence on the measurement environment is minimized and the risk of thrombosis at small flow blood velocities is decreased. But these systems are limited in terms of accuracy and resolution. The asked system requirements could only be reached by optimising the assembly and encapsulation techniques. To achieve the high degree of miniaturization numerical simulations were performed on the shape and size of the implant and led to the development of a specific metal housing consisting of two main components. A small measuring chamber will be placed into the portal vein and is rigidly fixed to a flat circular part that contains the pressure sensor chip and a transponder board and will be located outside on top of the vein. The main focus of the assembly process was based on a stress-free design and mounting of the components.

  13. Investigation of surface porosity measurements and compaction pressure as means to ensure consistent contact angle determinations

    DEFF Research Database (Denmark)

    Holm, René; Borkenfelt, Simon; Allesø, Morten

    2016-01-01

    for a compound is determined by its contact angle to a liquid, which in the present study was measured using the sessile drop method applied to a disc compact of the compound. Precise determination of the contact angle is important should it be used to either rank compounds or selected excipients to e.......g. increase the wetting from a solid dosage form. Since surface roughness of the compact has been suggested to influence the measurement this study investigated if the surface quality, in terms of surface porosity, had an influence on the measured contact angle. A correlation to surface porosity was observed......, however for six out of seven compounds similar results were obtained by applying a standard pressure (866MPa) to the discs in their preparation. The data presented in the present work therefore suggest that a constant high pressure should be sufficient for most compounds when determining the contact angle...

  14. Measurement of the local void fraction at high pressures in a heating channel

    International Nuclear Information System (INIS)

    Martin, R.

    1969-01-01

    Void fraction measurements were made in two phase flow boiling systems at high pressures in a uniformly heated, rectangular channel with a high aspect ratio. The local void fraction values were calculated from measurements of the absorption of a thin collimated X-ray beam (2 mm x 0.05 mm). The mean void fraction in a horizontal section results from integration of the local values across the section. At a fixed measuring station the quality and- void fraction were varied by changing the heat flux, flow rate and pressure systematically. Two channels were used differing in length and thickness (150.8 cm x 5.3 cm x 0.2 cm and the significant features of this study are: -1) The void fraction measurements are among the first obtained at such high pressure (80 to 140 kg/cm 2 ); -2) In the experimental region under consideration the measurements are systematic and numerous enough to allow accurate interpolations: mass velocity from 50 to 220 g/cm 2 .s, heat flux from 40 to 170 W/cm 2 and calculated steam quality from -0.2 to 0.2; -3) Many tests were performed under local boiling conditions with the mean temperature of the fluid below the saturation temperature; and -4) These results were compared to the predictions of certain models presented in the literature and simple empirical formulae were developed to fit the experimental results. (author) [fr

  15. “Multi-temperature” method for high-pressure sorption measurements on moist shales

    Energy Technology Data Exchange (ETDEWEB)

    Gasparik, Matus; Ghanizadeh, Amin; Gensterblum, Yves; Krooss, Bernhard M. [Energy and Mineral Resources Group (EMR), Institute of Geology and Geochemistry of Petroleum and Coal, Lochnerstr. 4-20, RWTH Aachen University, 52056 Aachen (Germany)

    2013-08-15

    A simple and effective experimental approach has been developed and tested to study the temperature dependence of high-pressure methane sorption in moist organic-rich shales. This method, denoted as “multi-temperature” (short “multi-T”) method, enables measuring multiple isotherms at varying temperatures in a single run. The measurement of individual sorption isotherms at different temperatures takes place in a closed system ensuring that the moisture content remains constant. The multi-T method was successfully tested for methane sorption on an organic-rich shale sample. Excess sorption isotherms for methane were measured at pressures of up to 25 MPa and at temperatures of 318.1 K, 338.1 K, and 348.1 K on dry and moisture-equilibrated samples. The measured isotherms were parameterized with a 3-parameter Langmuir-based excess sorption function, from which thermodynamic sorption parameters (enthalpy and entropy of adsorption) were obtained. Using these, we show that by taking explicitly into account water vapor as molecular species in the gas phase with temperature-dependent water vapor pressure during the experiment, more meaningful results are obtained with respect to thermodynamical considerations. The proposed method can be applied to any adsorbent system (coals, shales, industrial adsorbents) and any supercritical gas (e.g., CH{sub 4}, CO{sub 2}) and is particularly suitable for sorption measurements using the manometric (volumetric) method.

  16. Reproducibility indices applied to cervical pressure pain threshold measurements in healthy subjects.

    Science.gov (United States)

    Prushansky, Tamara; Dvir, Zeevi; Defrin-Assa, Ruth

    2004-01-01

    To apply various statistical indices for reproducibility analysis of pressure pain threshold measurements and to derive a preferred pressure pain threshold measurement protocol based on these indices. The pressure pain threshold of 3 pairs of right and left homologous cervical region sites were measured in 20 healthy subjects (10 women, 10 men) using a hand-held pressure algometer. Measurements took place on 2 occasions (test 1 and test 2) separated by a mean interval of 1 week. On each testing session, the site-related pressure pain thresholds were measured 3 times each according to 2 different protocols. Protocol A consisted of a repetitive order, namely 3 consecutive measurements at each site before proceeding to the next, whereas protocol B consisted of an alternate order in which 3 consecutive rounds of all individually tested sites took place. For test 1, protocol A was followed by protocol B with an hour interval. For test 2, the reverse order took place. The findings revealed no significant differences between the two protocols and indicated a significant rise (P test 1 to test 2 in both protocols. Absolute values (mean +/-SD) derived from the entire sample of pressure pain threshold sites ranged from 140 +/- 60 to 198.7 +/- 95 kPa (1.60 +/- 0.6 to 1.99 +/- 0.95 kg/cm, respectively). No significant gender or side differences were noted. Pearson r as well as the intraclass correlation coefficient revealed good to excellent reproducibility for both protocols and for all sites measured: r = 0.79-0.94 and intraclass correlation coefficient(3,3) = 0.85-0.96, respectively. To define site-specific cutoff values indicating change at the 95% confidence level, 1.96*SEM was calculated, and its values ranged from 31.6 to 58.2 kPa, which correspond to 16.8% to 32.8% of the absolute mean values. In addition, the limits of agreement, which depict the individual test-retest differences relative to their mean, indicated a heteroscedastic trend. The two protocols yielded

  17. Electrical resistance measurement in lithium under high pressure and low temperature

    CERN Document Server

    Shimizu, K; Amaya, K

    2002-01-01

    Lithium is known as a 'simple metal' and the lightest alkaline metal in the periodic table. At ambient pressure lithium forms a body-centred-cubic structure and the conduction electrons are considered to be almost free from interaction with the atomic core. However, Neaton and Ashcroft (Neaton J B and Ashcroft N W 1999 Nature 400 141) predicted that dense lithium at around 100 GPa will be found to transform to a low-symmetry phase and show a semi-metallic behaviour, in their calculation. Recently Hanfland et al (Hanfland M, Syassen K, Christensen N E and Novikov D L 2000 Nature 408 174) reported the experimental behaviour of the existence of new high-pressure phase of lithium above 40 GPa which tends towards symmetry-breaking transitions. Here we report electrical resistance measurements on lithium performed at pressures up to 35 GPa at the temperature of 80 K.

  18. Electrical resistance measurement in lithium under high pressure and low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, K [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Ishikawa, H [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Amaya, K [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan)

    2002-11-11

    Lithium is known as a 'simple metal' and the lightest alkaline metal in the periodic table. At ambient pressure lithium forms a body-centred-cubic structure and the conduction electrons are considered to be almost free from interaction with the atomic core. However, Neaton and Ashcroft (Neaton J B and Ashcroft N W 1999 Nature 400 141) predicted that dense lithium at around 100 GPa will be found to transform to a low-symmetry phase and show a semi-metallic behaviour, in their calculation. Recently Hanfland et al (Hanfland M, Syassen K, Christensen N E and Novikov D L 2000 Nature 408 174) reported the experimental behaviour of the existence of new high-pressure phase of lithium above 40 GPa which tends towards symmetry-breaking transitions. Here we report electrical resistance measurements on lithium performed at pressures up to 35 GPa at the temperature of 80 K.

  19. Measurement of negative ion mobilities in O2 and O3 mixtures at atmospheric pressure

    International Nuclear Information System (INIS)

    Itoh, H.; Norimoto, K.; Hayashi, T.

    1998-01-01

    Mobility measurements of negative molecular oxygen ions in pure oxygen and in an oxygen-ozone mixture are reported. A cascaded gap consisting of an ion drift gap and an ion detection gap was used in the experiment. The ion detection gap was formed by a positive point and a grounded plane electrode was operated at atmospheric pressure. The zero field mobility of negative molecular oxygen ions was determined to be 2.07+-0.02 cm 2 /V.s. A somewhat higher value of oxygen mobility was found at higher electric field/pressure ratios; this is presumed to be due to negative ozone ions. When changing the electric field/pressure ratio the mobility of negative oxygen ions in oxygen-ozone mixtures becomes smaller than that in pure oxygen; this is probably due to the cumulative effect of other particles produced by silent discharges. (J.U.)

  20. Time-resolved wave profile measurements in copper to Megabar pressures

    Energy Technology Data Exchange (ETDEWEB)

    Chhabildas, L C; Asay, J R

    1981-01-01

    Many time-resolved techniques have been developed which have greatly aided in the understanding of dynamic material behavior such as the high pressure-dynamic strength of materials. In the paper, time-resolved measurements of copper (at shock-induced high pressures and temperatures) are used to illustrate the capability of using such techniques to investigate high pressure strength. Continuous shock loading and release wave profiles have been made in copper to 93 GPa using velocity interferometric techniques. Fine structure in the release wave profiles from the shocked state indicates an increase in shear strength of copper to 1.5 GPa at 93 GPa from its ambient value of 0.08 GPa.

  1. Predation pressure in Ugandan cotton fields measured by a sentinel prey method

    DEFF Research Database (Denmark)

    Howe, Andrew Gordon; Nachman, Gösta; Lövei, Gábor L.

    2015-01-01

    Pest suppression by natural enemies is an important ecosystem service, which is a valuable resource to poor smallholders in developing countries. Diverse natural enemy assemblages of arthropod predators and parasitoids are documented in various regions in Africa, but our knowledge of their impact...... on herbivores in agroecosystems remains limited. We conducted experiments in cotton, Gossypium hirsutum L. (Malvaceae), under typical local agronomic practices in Uganda to assess levels of predation pressure ascribed to natural enemies. We measured predation rates on artificial caterpillars made of plasticine...... glued to cotton plants. Predation pressure on cotton fields varied between 1.96 and 4.1% per day, but was not significantly influenced by cotton treatments (insecticide/no insecticide, monocropping/intercropping with Phaseolus spp.). Predation pressure in non-crop habitats adjacent to cotton fields...

  2. [Improved care of foot ulcer using foot pressure measurement and foot care method sheet].

    Science.gov (United States)

    Tinen, Takaaki; Iha, Hiroyuki; Miyagi, Chiaki; Yusa, Masaru; Taira, Hitomi; Matsumoto, Kinuko

    2008-09-01

    At this sanatorium, the number of foot bottom ulcer patients was 13 and the tenure of the foot bottom ulcer was average 11 years. According to the treatment that was not unified, we thought about the cause of the prolongation. Therefore, we made evaluation and care method sheet ("foot care sheet") of the ulcer for the unification. We used the foot pressure measurement system (F-scan) to 4 patients for the pressure dispersion of the ulcer. We devised the protection law of the ulcer, and an ulcer did not require pressure more than 5 kilos/cm2. We recorded the size of the ulcer, weight of the liquid from ulcer, a photograph to care sheet once a week. I performed ulcer protection law and management with the foot care sheet to 4 patients for average 4 months. As a result, the ulcers of 3 patients out of 4 patients became small.

  3. Occlusion cuff for routine measurement of digital blood pressure and blood flow

    DEFF Research Database (Denmark)

    Lassen, N A; Krähenbühl, B; Hirai, M

    1977-01-01

    A miniaturized blood pressure cuff made of plastic material and applicable to fingers and toes is described. The cuff was compared to rubber cuffs and to bladder-free cuffs. It was found to be more reliable than the former type and much easier to use than the latter type. It is recommended for us...... in conjunction with a mercury-in-Silastic strain gauge for routine measurement of digital blood pressure and blood flow in patients with arterial disease.......A miniaturized blood pressure cuff made of plastic material and applicable to fingers and toes is described. The cuff was compared to rubber cuffs and to bladder-free cuffs. It was found to be more reliable than the former type and much easier to use than the latter type. It is recommended for use...

  4. Measurement and modeling of high-pressure (vapour + liquid) equilibria of (CO2 + alcohol) binary systems

    International Nuclear Information System (INIS)

    Gutierrez, Jorge E.; Bejarano, Arturo; Fuente, Juan C. de la

    2010-01-01

    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 2 + 1-propanol), (CO 2 + 2-methyl-1-propanol), (CO 2 + 3-methyl-1-butanol), and (CO 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 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.

  5. Direct measurement of pressures involved in vocal exercises using semi-occluded vocal tracts.

    Science.gov (United States)

    Robieux, Camille; Galant, Camille; Lagier, Aude; Legou, Thierry; Giovanni, Antoine

    2015-10-01

    The aim of this study was to rank vocal exercises using semi-occluded vocal tracts (SOVT) as a function of their effect on subglottal pressure (SGP) and on transglottal pressure (TGP). Direct measurements were performed in two healthy females. The correct realization of vocal exercises was controlled by maintaining a constant airflow at the phonation onset. TGP varied from 1.8 to 5.9 hPa among SOVT, in the same range as phonation threshold pressure values. SGP varied among subjects from 19.4 for 2-mm straw to 3.2 hPa for closed vowel. SOVT could be ranked in voice rehabilitation from the greatest to the smallest effects on SGP as following: 1) 2-mm straw; 2) 5-mm straw and fricative /v/; 3) 8-mm straw and nasals /m/ and /n/; 4) vowel /i/.

  6. Estimation of the viscosities of silicate liquids at high pressure from measurements of oxygen diffusivity

    Science.gov (United States)

    Rubie, D. C.; Ross, C. R., II; Carroll, M. R.; Elphick, S. C.

    1992-01-01

    The dynamics and evolution of a magma ocean depend significantly on the structure and physical properties of silicate liquids at high pressure. Viscosity is particularly important because of its effect on the dynamics of convection and crystal setting. Traditionally, the viscosities of silicate liquids have been measured at high pressure by falling sphere viscometry but, due to some limitations of this technique, few measurements have been made at pressures exceeding 2.5 GPa. An alternative approach, which has previously been proven up to 2 GPa, is to use high pressure measurements of oxygen self-diffusivity (D) to estimate viscosity (eta) from the Eyring relationship eta = kT/D lambda (where k is the Boltzmann constant, T is absolute temperature, and lambda is the diffusive jump distance). We have performed preliminary experiments on Na2Si4O9 liquid in order to explore the feasibility of this method up to pressures in excess of 10 GPa. Diffusion couples were prepared from glass starting materials with one half of the sample enriched in O-18 and the other half containing the natural abundance (0.2 wt percent). Diffusion experiments were performed at 1600 to 1800 C at pressures in the range of 2.5 to 10 GPa for times up to 6 minutes using a 1200 ton multianvil apparatus. Oxygen diffusivities were derived from the resulting O-18 concentration profiles, which were analyzed using an ion microprobe. At 1800 C, oxygen diffusivities increase continuously from 1 x 10(exp -10) m(exp -2) s(exp -1) at 2.5 Gpa to 5 x 10(exp -10) m(exp -2) s(exp -1) at 10 GPa. From the Eyring relationship, the viscosity of Na2SiO9 liquid is predicted to decrease by approx. 0.7 log units over this pressure range at 1800 C. These trends, which can be related to changes in the structure of the liquid at high pressure, are in agreement with results of molecular dynamics calculations. These results suggest that it should be possible to estimate the viscosities of silicate liquids up to at least 15

  7. The Effect of Electrokinetic Controlled Wettability on Externally Measured Pressures for a Micro-Fluidic Channel

    Science.gov (United States)

    Zhou, X.; Nolte, D. D.; Pyrak-Nolte, L. J.

    2017-12-01

    The hysteretic relationship between capillary pressure (Pc) on saturation (S) has been shown to be a projection of a higher-dimensional surface that depends on interfacial area per volume (IAV) as the additional state variable. Most studies that validate the capillary-pressure-saturation-IAV relationship are performed on 2D micro-models or cores where scanning is performed in pressure and not in saturation. We have developed an EWOD technique (electro-wetting on dielectric) to internally manipulate fluid saturation to determine the effect on externally measured pressures. Applying electric fields to electrolytic fluids changes the contact angle among the fluids and the solid. For a parallel-plate electro-wetting set-up, the pressure difference is given by gsl (cosq'EW - cosqEW )/d', where d' is the aperture, qEQ and q'EW are the contact angles before and after the application of voltage, V, and gsl is the interfacial tension between the solid and liquid phases. This pressure difference enables direct control over internal fluid distributions. The contact angle reverts to the original value when V = 0. A sealed micro-model with Electro-Wetting on Dielectric (EWOD) electrodes was fabricated using a PDMS wedge-shaped channel with an entrance width of 1 mm and an exit width of 2 mm. The channel length was 2 mm, and had a depth of 0.9 mm. The PDMS channel was attached to an aluminum plate that served as the ground electrode. An ITO slide coated with PDMS formed the high voltage electrode and was used to seal the micro-model. X-ray Micro-CT scans showed that the contact angle between electrodes changes from from 110˚ (non-wetting) to 70˚ (wetting) for an applied voltage of 318 V AC. By applying voltage to the wedge-shaped micromodel, with the inlet and the outlet opened to the atmosphere, the externally measured capillary pressure remained constant even though the fluid-air interface moved and the saturation increased. For a closed system, the externally measured

  8. Multiparameter Flowfield Measurements in High-Pressure, Cryogenic Environments Using Femtosecond Lasers

    Science.gov (United States)

    Burns, Ross A.; Danehy, Paul M.; Peters, Christopher J.

    2016-01-01

    Femtosecond laser electronic excitation tagging (FLEET) and Rayleigh scattering (RS) from a femtosecond laser are demonstrated in the NASA Langley 0.3-m Transonic Cryogenic Tunnel (TCT). The measured signals from these techniques are examined for their thermodynamic dependencies in pure nitrogen. The FLEET signal intensity and signal lifetimes are found to scale primarily with the gas density, as does the RS signal. Several models are developed, which capture these physical behaviors. Notably, the FLEET and Rayleigh scattering intensities scale linearly with the flow density, while the FLEET signal decay rates are a more complex function of the thermodynamic state of the gas. The measurement of various flow properties are demonstrated using these techniques. While density was directly measured from the signal intensities and FLEET signal lifetime, temperature and pressure were measured using the simultaneous FLEET velocity measurements while assuming the flow had a constant total enthalpy. Measurements of density, temperature, and pressure from the FLEET signal are made with accuracies as high as 5.3 percent, 0.62 percent, and 6.2 percent, respectively, while precisions were approximately 10 percent, 0.26 percent, and 11 percent for these same quantities. Similar measurements of density from Rayleigh scattering showed an overall accuracy of 3.5 percent and a precision of 10.2 percent over a limited temperature range (T greater than 195 K). These measurements suggest a high degree of utility at using the femtosecond-laser based diagnostics for making multiparameter measurements in high-pressure, cryogenic environments such as large-scale TCT facilities.

  9. In cadavers, directly measured mucosal pressures are similar for the Unique and the Soft Seal laryngeal mask airway devices

    NARCIS (Netherlands)

    Keller, Christian; Brimacombe, Joseph; Moriggl, Bernhard; Lirk, Philipp; von Goedecke, Achim

    2004-01-01

    We compare the Soft Seal and Unique single-use, plastic laryngeal mask airway devices with respect to intracuff pressure, directly measured mucosal pressure and in vitro elastance. Ten fresh male cadavers were studied. Microchip pressure sensors were attached to the following locations: A) the

  10. An umbilical data-acquisition system for measuring pressures between the foot and shoe.

    Science.gov (United States)

    Zhu, H S; Maalej, N; Webster, J G; Tompkins, W J; Bach-y-Rita, P; Wertsch, J J

    1990-09-01

    We have developed an umbilical data-acquisition system for measuring pressures between the foot and shoe during walking. It consists of pressure sensors in the insoles of shoes, amplifier circuits, umbilical cables, an analog-to-digital converter, and a graphics display card in an IBM PC for real-time data collection and display. The applied pressure on a sensor decreases its resistance, which causes the output voltage of the amplifier circuit to increase. We attach seven sensors to the surface of each insole of a pair of extra-depth shoes and calibrate all the sensors in the insole before and after each test using a load cell as a reference. The IBM PC samples the outputs from the sensor and the load cell and stores a piecewise linear lookup table for use in compensation for the nonlinearity of the sensor. On the PC's graphics display, two programs provide displays of foot pressures as real-time bar graphs or as analog pressure versus time curves.

  11. Blood pressure measurement in children: which method? which is the gold standard.

    Science.gov (United States)

    Vidal, Enrico; Murer, Luisa; Matteucci, Maria Chiara

    2013-01-01

    The burden of hypertension has become increasingly prevalent in children. Hypertension that begins in childhood can carry on into adulthood, therefore early detection, accurate diagnosis and effective therapy of high blood pressure may improve long-term outcomes of children and adolescents. As far as pediatric hypertension is concerned, doubts still persist about the right instruments, modalities and standards of reference that should be used in routine practice. Due to the dynamic process of growth and development, many physiological parameters undergo intensive change with age. Therefore, in children, the definition of hypertension can not rely on a single blood pressure level but should be based on age- and height-specific percentiles. In this review, we introduce the nephrologist to the correct definition of high blood pressure in children. Moreover, we specifically address the main characteristics of different modalities for blood pressure measurement in children, focusing on practical aspects. The latest international guidelines and appropriate standards of reference for office, ambulatory and home blood pressure data collection are presented. As clinicians are being faced with a greater number of children with hypertension, they should be aware of these peculiarities.

  12. Detection of atmospheric pressure loading using very long baseline interferometry measurements

    Science.gov (United States)

    Vandam, T. M.; Herring, T. A.

    1994-01-01

    Loading of the Earth by the temporal redistribution of global atmospheric mass is likely to displace the positions of geodetic monuments by tens of millimeters both vertically and horizontally. Estimates of these displacements are determined by convolving National Meteorological Center (NMC) global values of atmospheric surface pressure with Farrell's elastic Green's functions. An analysis of the distances between radio telescopes determined by very long baseline interferometry (VLBI) between 1984 and 1992 reveals that in many of the cases studied there is a significant contribution to baseline length change due to atmospheric pressure loading. Our analysis covers intersite distances of between 1000 and 10,000 km and is restricted to those baselines measured more than 100 times. Accounting for the load effects (after first removing a best fit slope) reduces the weighted root-mean-square (WRMS) scatter of the baseline length residuals on 11 of the 22 baselines investigated. The slight degradation observed in the WRMS scatter on the remaining baselines is largely consistent with the expected statistical fluctuations when a small correction is applied to a data set having a much larger random noise. The results from all baselines are consistent with approximately 60% of the computed pressure contribution being present in the VLBI length determinations. Site dependent coefficients determined by fitting local pressure to the theoretical radial displacement are found to reproduce the deformation caused by the regional pressure to within 25% for most inland sites. The coefficients are less reliable at near coastal and island stations.

  13. Airborne Lidar Measurements of Atmospheric Pressure Made Using the Oxygen A-Band

    Science.gov (United States)

    Riris, Haris; Rodriquez, Michael; Allan, Graham R.; Hasselbrack, William E.; Stephen, Mark A.; Abshire, James B.

    2011-01-01

    We report on airborne measurements of atmospheric pressure using a fiber-laser based lidar operating in the oxygen A-band near 765 nm and the integrated path differential absorption measurement technique. Our lidar uses fiber optic technology and non-linear optics to generate tunable laser radiation at 765 nm, which overlaps an absorption line pair in the Oxygen A-band. We use a pulsed time resolved technique, which rapidly steps the laser wavelength across the absorption line pair, a 20 cm telescope and photon counting detector to measure Oxygen concentrations.

  14. Near-field acoustic holography with sound pressure and particle velocity measurements

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren

    of the particle velocity has notable potential in NAH, and furthermore, combined measurement of sound pressure and particle velocity opens a new range of possibilities that are examined in this study. On this basis, sound field separation methods have been studied, and a new measurement principle based on double...... layer measurements of the particle velocity has been proposed. Also, the relation between near-field and far-field radiation from sound sources has been examined using the concept of the supersonic intensity. The calculation of this quantity has been extended to other holographic methods, and studied...

  15. Fuel rod-to-support contact pressure and stress measurement for CHASNUPP-1(PWR) fuel

    International Nuclear Information System (INIS)

    Waseem; Elahi, N.; Siddiqui, A.; Murtaza, G.

    2011-01-01

    Research highlights: → A detailed finite element model of spacer grid cell with fuel rod-to-support has been developed to determine the contact pressure between the supports of the grid and fuel rod cladding. → The spring hold-down force is calculated using the contact pressure obtained from the FE model. → Experiment has also been conducted in the same environment for the measurement of this force. → The spring hold-down force values obtained from both studies confirm the validation of this analysis. → The stress obtained through this analysis is less than the yield strength of spacer grid material, thus fulfils the structural integrity criteria of grid. - Abstract: This analysis has been made in an attempt to measure the contact pressure of the PWR fuel assembly spacer grid spring and to verify its structural integrity at room temperature in air. A detailed finite element (FE) model of spacer grid cell with fuel rod-to-support has been developed to determine the contact pressure between the supports of the grid and fuel rod cladding. The FE model of a fuel rod-to-support system is produced with shell and contact elements. The spring hold-down force is calculated using the contact pressure obtained from the FE model. Experiment has also been conducted in the same environment for the measurement of this force. The spring hold-down force values obtained from both studies are compared, which show good agreement, and in turn confirm the validation of this analysis. The Stress obtained through this analysis is less than the yield strength of spacer grid material (Inconel-718), thus fulfils the structural integrity criteria of grid.

  16. Reproducibility of proximal and distal transcutaneous oxygen pressure measurements during exercise in stage 2 arterial claudication.

    Science.gov (United States)

    Bouyé, P; Picquet, J; Jaquinandi, V; Enon, B; Leftheriotis, G; Saumet, J-L; Abraham, P

    2004-06-01

    Although transcutaneous oxygen pressure measurements (tcpO2) are largely used in the investigation of vascular patients, its reproducibility is still debated. Indeed an unpredictable gradient exists between arterial and transcutaneous oxygen pressure. We hypothesised that indices taking into account changes over time and independent of absolute starting values would be more reproducible than other indices. comparative test-retest procedure (1 to 13 days between tests). institutional practice, ambulatory care. 15 subjects with stage 2 claudication. tcpO2 recordings at rest and at exercise during the 2 treadmill tests. calculation of the Delta-from-rest of oxygen pressure index (limb tcpO2 changes minus chest tcpO2 changes), of the resting - or minimal values attained during exercise - of absolute tcpO2 and of the regional perfusion index (regional perfusion index: ration of limb to chest). Both absolute tcpO2 and regional perfusion index at rest showed low reproducibility. During exercise the best reproducibility was attained through Delta-from-rest of oxygen pressure index calculation. Equations from the linear regression analysis (test 2 versus test 1) were 0.88 x -4.2 (r(2)=0.82) at the buttock level and 0.82 x -3.8 (r(2)=0.80) at the calf level. TcpO2 measurement on the calf or buttock during exercise, is a reproducible measurement in patients with vascular claudication, specifically when corrected for exercise-induced systemic pO2 changes trough Delta-from-rest of oxygen pressure calculation.

  17. Reference intervals for intraocular pressure measured by rebound tonometry in ten raptor species and factors affecting the intraocular pressure.

    Science.gov (United States)

    Reuter, Anne; Müller, Kerstin; Arndt, Gisela; Eule, Johanna Corinna

    2011-09-01

    Intraocular pressure (IOP) was measured with the TonoVet rebound tonometer in 10 raptor species, and possible factors affecting IOP were investigated. A complete ophthalmic examination was performed, and IOP was assessed in 2 positions, upright and dorsal recumbency, in 237 birds belonging to the families Accipitridae, Falconidae, Strigidae, and Tytonidae. Mean IOP values of healthy eyes were calculated for each species, and differences between families, species, age, sex, left and right eye, as well as the 2 body positions were evaluated. Physiologic fluctuations of IOP were assessed by measuring IOP serially for 5 days at the same time of day in 15 birds of 3 species. Results showed IOP values varied by family and species, with the following mean IOP values (mm Hg +/- SD) determined: white-tailed sea eagle (Haliaeetus albicilla), 26.9 +/- 5.8; red kite (Milvus milvus), 13.0 +/- 5.5; northern goshawk (Accipiter gentilis), 18.3 +/- 3.8; Eurasian sparrowhawk (Accipiter nisus), 15.5 +/- 2.5; common buzzard (Buteo buteo), 26.9 +/- 7.0; common kestrel (Falco tinnunculus), 9.8 +/- 2.5; peregrine falcon, (Falco peregrinus), 12.7 +/- 5.8; tawny owl (Strix aluco), 9.4 +/- 4.1; long-eared owl (Asio otus), 7.8 +/- 3.2; and barn owl (Tyto alba), 10.8 +/- 3.8. No significant differences were found between sexes or between left and right eyes. In goshawks, common buzzards, and common kestrels, mean IOP was significantly lower in juvenile birds than it was in adult birds. Mean IOP differed significantly by body position in tawny owls (P = .01) and common buzzards (P = .04). By measuring IOP over several days, mean physiologic variations of +/- 2 mm Hg were detected. Differences in IOP between species and age groups should be considered when interpreting tonometric results. Physiologic fluctuations of IOP may occur and should not be misinterpreted. These results show that rebound tonometry is a useful diagnostic tool in measuring IOP in birds of prey because it provides rapid

  18. Measurement and interpretation of threshold stress intensity factors for steels in high-pressure hydrogen gas.

    Energy Technology Data Exchange (ETDEWEB)

    Dadfarnia, Mohsen (University of Illinois at Urbana-Champaign, Urbana, IL); Nibur, Kevin A.; San Marchi, Christopher W.; Sofronis, Petros (University of Illinois at Urbana-Champaign, Urbana, IL); Somerday, Brian P.; Foulk, James W., III; Hayden, Gary A. (CP Industries, McKeesport, PA)

    2010-07-01

    Threshold stress intensity factors were measured in high-pressure hydrogen gas for a variety of low alloy ferritic steels using both constant crack opening displacement and rising crack opening displacement procedures. The sustained load cracking procedures are generally consistent with those in ASME Article KD-10 of Section VIII Division 3 of the Boiler and Pressure Vessel Code, which was recently published to guide design of high-pressure hydrogen vessels. Three definitions of threshold were established for the two test methods: K{sub THi}* is the maximum applied stress intensity factor for which no crack extension was observed under constant displacement; K{sub THa} is the stress intensity factor at the arrest position for a crack that extended under constant displacement; and K{sub JH} is the stress intensity factor at the onset of crack extension under rising displacement. The apparent crack initiation threshold under constant displacement, K{sub THi}*, and the crack arrest threshold, K{sub THa}, were both found to be non-conservative due to the hydrogen exposure and crack-tip deformation histories associated with typical procedures for sustained-load cracking tests under constant displacement. In contrast, K{sub JH}, which is measured under concurrent rising displacement and hydrogen gas exposure, provides a more conservative hydrogen-assisted fracture threshold that is relevant to structural components in which sub-critical crack extension is driven by internal hydrogen gas pressure.

  19. Laser-based measurements of OH in high pressure CH4/air flames

    Science.gov (United States)

    Battles, B. E.; Hanson, R. K.

    1991-01-01

    Narrow-linewidth laser absorption measurements are reported from which mole fraction and temperature of OH are determined in high-pressure (1-10 atm), lean CH4/air flames. These measurements were made in a new high pressure combustion facility which incorporates a traversable flat flame burner, providing spatially and temporally uniform combustion gases at pressures up to 10 am. A commercially avialable CW ring dye laser was used with an intracavity doubling crystal to provide near-UV single mode output at approximately 306 nm. The UV beam was rapidly scanned over 120 GHz (0.1 sec scan duration) to resolve the absorption lineshape of the A-X (0,0) R1(7)/R1(11) doublet of the OH radical. From the doublet's absorption lineshape, the temperature was determined; and from peak absorption, Beer's Law was employed to find the mole fraction of OH. These data were obtained as a function of height above the flame at various pressures.

  20. Agreement of high definition oscillometry with direct arterial blood pressure measurement at different blood pressure ranges in horses under general anaesthesia.

    Science.gov (United States)

    Tünsmeyer, Julia; Hopster, Klaus; Feige, Karsten; Kästner, Sabine Br

    2015-05-01

    To determine the agreement of high definition oscillometry (HDO) with direct arterial blood pressure measurements in normotensive, hypotensive and hypertensive horses during general anaesthesia. Experimental study. Seven healthy warmblood horses, aged 3-11 years, weighing 470-565 kg. Measurements from a HDO device with the cuff placed around the base of the tail were compared with pressures measured invasively from the facial artery. High blood pressures were induced by intravenous (IV) administration of dobutamine (5 μg kg(-1) minute(-1)) over ten minutes followed by norepinephrine (0.1 mg kg(-1) IV) and low pressures by increasing the inspired fraction of isoflurane and administration of nitroglycerine (0.05 mg kg(-1) IV). For analysis three pressure levels were determined: high (MAP>110 mmHg), normal (60 mmHgstandard deviation for SAP, MAP and DAP were 0.1 ± 19.4 mmHg, 0.5 ± 14.0, 4.7 ± 15.6, respectively. At high pressure levels bias and SD were 26.1 ± 37.3 (SAP), 4.2 ± 19.4 (MAP), 1.5 ± 16.8 (DAP) and at low pressures -20.0 ± 20.9 (SAP), -11.4 ± 19.6 (MAP), -4.7 ± 20.1 (DAP), with HDO measurements at a MAP <50 mmHg often failing. Good agreement with invasive arterial blood pressures was obtained with HDO at normotensive levels in horses. At high and low pressure ranges HDO was unreliable. Therefore, if haemodynamic instability is expected, invasive measurement remains preferable. © 2014 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.

  1. An accurate measurement of the Rosemount 1152 differential pressure cell response time

    International Nuclear Information System (INIS)

    Hinds, H.W.; Gao, Y.; Tonner, P.D.

    1997-01-01

    The primary heat-transport (PHT) system of a CANDU reactor includes four quadrants of reactor coolant channels, each fed from its own inlet header through a large number of inlet feeders. As part of the safety shutdown system 1 (SDS1) and Reactor Regulating System (RRS) of CANDU reactors, differential-pressure (DP) cells are used to monitor the reactor coolant flows in each quadrant and to register changes with a prescribed response time. This paper describes an accurate in-situ measurement of the response time of two Rosemount 1152 DPA22PB DP cells, one from SDS1 and one from an RRS fully instrumented channel. The response time measurement was done using high-frequency pressure-measurement devises temporarily installed on the high- and low-pressure sides of the DP cells. The results suggest that the actual time constant of the Rosemount DP cell is much faster than indicated in the specification which is based on the traditional instrument-air-step-response measurement method. Furthermore, the actual time constant is much faster than that assumed in the safety analysis report. An examination of the instrument-air-step-response method indicates that is produces conservative estimates of time constants, especially for small time constants. If further work confirms this finding it suggests that the actual time constant may be increased considerably without exceeding the time constant assumed in the safety analysis. (author)

  2. Viscosity measurements of water at high temperatures and pressures using dynamic light scattering.

    Science.gov (United States)

    Deguchi, Shigeru; Ghosh, Swapan K; Alargova, Rossitza G; Tsujii, Kaoru

    2006-09-21

    The application of dynamic light scattering to measure viscosity of water at high temperatures and pressures is demonstrated. Viscosity was obtained from the translational diffusion coefficient of probe particles dispersed in the medium by the Einstein-Stokes relationship. Measurements were carried out with polystyrene latex, colloidal silica, and colloidal gold. Under a constant pressure of 25 MPa, good agreement was found between the measured and calculated viscosities up to 275 degrees C with the polystyrene latex, 200 degrees C with the colloidal silica, and 297 degrees C with the colloidal gold. It was found that failure of the measurements at high temperatures is ascribed to change in either the dispersion stability or chemical stability of the probe particles. The present results indicate that the technique could also be used for other supercritical fluids having high critical temperature and pressure, such as methanol (T(c) = 239.4 degrees C, P(c) = 8.1 MPa) and ethanol (T(c) = 243.1 degrees C, P(c) = 6.4 MPa).

  3. Diagnostic accuracy of manual office blood pressure measurement in ambulatory hypertensive patients in Korea.

    Science.gov (United States)

    Kim, Sehun; Park, Jin Joo; Lee, Seung-Ah; Cho, Youngjin; Yoon, Yeonyee E; Oh, Il-Young; Yoon, Chang-Hwan; Suh, Jung-Won; Cho, Young-Seok; Youn, Tae-Jin; Cho, Goo-Yeong; Chae, In-Ho; Lee, Hae-Young; Shin, Jinho; Park, Sungha; Choi, Dong-Ju

    2018-01-01

    Currently, office blood pressure (OBP) is the most widely used method of measuring blood pressure (BP) in daily clinical practice. However, data on the diagnostic accuracy of OBP in reference to ambulatory blood pressure (ABP) are scarce in Korea. In retrospective and prospective cohorts, manual OBP and ABP measurements were compared among ambulatory hypertensive patients. Hypertension was defined as systolic OBP ≥ 140 mmHg and/or diastolic OBP ≥ 90 mmHg, and systolic ABP ≥ 130 mmHg and/or diastolic ABP ≥ 80 mmHg. In the retrospective cohort (n = 903), the mean OBP1 (before ABP measurement) was higher than ABP in both systolic (138 ± 17 mmHg vs. 123 ± 13 mmHg, p higher false negative results (masked or under-treated hypertension) than did female patients (26.1% vs. 17.8%, p = 0.003), whereas female patients had a higher false positive rate (white-coat or over-treated hypertension) than did male patients (28.7% vs. 15.2%, p accuracy of manual OBP is low in reference to ABP. Men and women have different patterns of discordance. These findings indicate that management of hypertensive patients with manual OBP measurements may be suboptimal and encourages the use of ABP in ambulatory hypertensive patients.

  4. Intraocular pressure measurement in cynomolgus monkeys. Tono-Pen versus manometry.

    Science.gov (United States)

    Peterson, J A; Kiland, J A; Croft, M A; Kaufman, P L

    1996-05-01

    In living cynomolgus monkey eyes, the authors compared manometrically set and measured intraocular pressure (IOP) with simultaneous IOP readings obtained with the Tono-Pen (TP), a handheld applanation tonometer based on the Mackay-Marg principle. In three pentobarbital-anesthetized cynomolgus monkeys, IOP was set and measured manometrically after anterior chamber cannulation through the peripheral cornea with a 26-gauge needle connected to a vertically adjustable reservoir and a pressure transducer. Intraocular pressure was raised in approximately 5 mm Hg steps from 5 mm Hg to 60 mm Hg and then lowered in 5 mm Hg steps to 5 mm Hg, with TP measurements taken at each increment and decrement in open and stopcock modes. Linear regression analysis of TP on manometric readings for grouped data from all six eyes, with each data point representing the average of all the TP readings from one eye at each manometric pressure setting, showed a slope 0.692 +/- 0.016 and 0.683 +/- 0.023 (both significantly different from 1; P < 0.001), intercept 1.21 +/- 0.60 and 1.64 +/- 0.82 mm Hg (both significantly different from 0.0, P < 0.05), and correlation coefficient 0.981 and 0.96 in open stopcock and closed stopcock mode, respectively. There were no striking differences when the data were analyzed for individual eyes or animals, for open versus closed stopcock manometry, or for increasing versus decreasing manometric IOP. The TP provides reproducible measurements of IOP in cynomolgus monkeys, with measurement accuracy dependent on the generation of an appropriate calibration curve.

  5. Formaldehyde preparation methods for pressure and temperature dependent laser-induced fluorescence measurements

    Science.gov (United States)

    Burkert, A.; Müller, D.; Rieger, S.; Schmidl, G.; Triebel, W.; Paa, W.

    2015-12-01

    Formaldehyde is an excellent tracer for the early phase of ignition of hydrocarbon fuels and can be used, e.g., for characterization of single droplet ignition. However, due to its fast thermal decomposition at elevated temperatures and pressures, the determination of concentration fields from laser-induced fluorescence (LIF) measurements is difficult. In this paper, we address LIF measurements of this important combustion intermediate using a calibration cell. Here, formaldehyde is created from evaporation of paraformaldehyde. We discuss three setups for preparation of formaldehyde/air mixtures with respect to their usability for well-defined heating of formaldehyde/air mixtures. The "basic setup" uses a resist heater around the measurement cell for investigation of formaldehyde near vacuum conditions or formaldehyde/air samples after sequential admixing of air. The second setup, described for the first time in detail here, takes advantage of a constant flow formaldehyde/air regime which uses preheated air to reduce the necessary time for gas heating. We used the constant flow system to measure new pressure dependent LIF excitation spectra in the 343 nm spectral region (414 absorption band of formaldehyde). The third setup, based on a novel concept for fast gas heating via excitation of SF6 (chemically inert gas) using a TEA (transverse excitation at atmospheric pressure) CO2 laser, allows to further minimize both gas heating time and thermal decomposition. Here, an admixture of CO2 is served for real time temperature measurement based on Raman scattering. The applicability of the fast laser heating system has been demonstrated with gas mixtures of SF6 + air, SF6 + N2, as well as SF6 + N2 + CO2 at 1 bar total pressure.

  6. Venous cuff pressures from 30 mmHg to diastolic pressure are recommended to measure arterial inflow by plethysmography.

    NARCIS (Netherlands)

    Groothuis, J.T.; Vliet, L. van; Kooijman, H.M.; Hopman, M.T.E.

    2003-01-01

    Venous occlusion strain gauge plethysmography (VOP) is based on the assumption that the veins are occluded and arterial inflow is undisturbed by the venous cuff pressure. Literature is not clear concerning the pressure that should be used. The purpose of this study was to determine the optimal

  7. Pressure and Humidity Measurements at the MSL Landing Site Supported by Modeling of the Atmospheric Conditions

    Science.gov (United States)

    Harri, A.; Savijarvi, H. I.; Schmidt, W.; Genzer, M.; Paton, M.; Kauhanen, J.; Atlaskin, E.; Polkko, J.; Kahanpaa, H.; Kemppinen, O.; Haukka, H.

    2012-12-01

    The Mars Science Laboratory (MSL) called Curiosity Rover landed safely on the Martian surface at the Gale crater on 6th August 2012. Among the MSL scientific objectives are investigations of the Martian environment that will be addressed by the Rover Environmental Monitoring Station (REMS) instrument. It will investigate habitability conditions at the Martian surface by performing a versatile set of environmental measurements including accurate observations of pressure and humidity of the Martian atmosphere. This paper describes the instrumental implementation of the MSL pressure and humidity measurement devices and briefly analyzes the atmospheric conditions at the Gale crater by modeling efforts using an atmospheric modeling tools. MSL humidity and pressure devices are based on proprietary technology of Vaisala, Inc. Humidity observations make use of Vaisala Humicap® relative humidity sensor heads and Vaisala Barocap® sensor heads are used for pressure observations. Vaisala Thermocap® temperature sensors heads are mounted in a close proximity of Humicap® and Barocap® sensor heads to enable accurate temperature measurements needed for interpretation of Humicap® and Barocap® readings. The sensor heads are capacitive. The pressure and humidity devices are lightweight and are based on a low-power transducer controlled by a dedicated ASIC. The transducer is designed to measure small capacitances in order of a few pF with resolution in order of 0.1fF (femtoFarad). The transducer design has a good spaceflight heritage, as it has been used in several previous missions, for example Mars mission Phoenix as well as the Cassini Huygens mission. The humidity device has overall dimensions of 40 x 25 x 55 mm. It weighs18 g, and consumes 15 mW of power. It includes 3 Humicap® sensor heads and 1 Thermocap®. The transducer electronics and the sensor heads are placed on a single multi-layer PCB protected by a metallic Faraday cage. The Humidity device has measurement range

  8. Reliability and minimal detectable change in foot pressure measurements in typically developing children.

    Science.gov (United States)

    Niiler, Timothy; Church, Chris; Lennon, Nancy; Henley, John; George, Ameeka; Taylor, Daveda; Montes, Angelica; Miller, Freeman

    2016-12-01

    In pedobarography, clinically meaningful comparison of measurements within or between subjects is limited by data variability and measurement error. This study aims to determine the components of the minimal detectable change (MDC) in impulse across all foot regions and the reliability of these measures. A convenience sample of foot pressures from 108 visits by normal, healthy subjects aged 2-17 years was studied. Each subject had three pedobarograph measurements taken per foot, with six subjects returning for a second visit for assessment of day-to-day variability. Using a five-region mask, segmental impulses were determined, and from these we obtained the coronal plane pressure index (CPPI). Inter-rater, intra-rater, and day-to-day data were analyzed using intraclass correlation coefficients (ICC) to quantify reliability. Variability of the data was analyzed to quantify the MDC. Inter- and intra-rater reliability was high for all measurements while variability was low, indicating small direct measurement error. Generally, the largest contributing factor to the MDC was day-to-day variability. Step-to-step variability was more dependent on foot segment than age although minor age-related changes were noted. Finally, the high relative variability in the CPPI and the medial mid foot impulse resulted in very high MDCs for these measures. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. MEASUREMENT OF ENDOTRACHEAL TUBE CUFF PRESSURE IN MECHANICALLYVENTILATED PATIENTS ON ARRIVAL TO INTENSIVE CARE UNIT - A CROSS-SECTIONAL STUDY

    Directory of Open Access Journals (Sweden)

    Arun Kumar Ajjappa

    2017-04-01

    Full Text Available BACKGROUND The monitoring of Endotracheal Tube (ETT cuff pressure in intubated patients on arrival to intensive care unit is very essential. The cuff pressure must be within an optimal range of 20-30cm H2O ensuring ventilation with no complications related to cuff overinflation and underinflation. This can be measured with a cuff pressure manometer. The aim of the study is to measure the endotracheal tube cuff pressure in patients on arrival to intensive care unit and to identify prevalence of endotracheal cuff underinflation and overinflation. MATERIALS AND METHODS A cross-sectional study was done on mechanically-ventilated patients who were intubated in casualty (emergency department on arrival to intensive care unit in S.S. Institute of Medical Sciences and Research Centre, Davangere. About 50 critically-ill patients intubated with a high volume, low pressure endotracheal tube were included in the study. An analogue manometer was used to measure the endotracheal tube cuff pressure. It was compared with the recommended level. The settings of mechanical ventilation, endotracheal tube size and peak airway pressure were recorded. RESULTS It was found that the mean cuff pressure was 64.10 cm of H2O with a standard deviation of 32.049. Of the measured cuff pressures, only 2% had pressures within an optimal range (20-30cm of H2O. 88% had cuff pressures more than 30cm of H2O. The mean peak airway pressure found to be 20.50cm of H2O with a Standard Deviation (SD of 5.064. CONCLUSION This study is done to emphasise the importance of cuff pressure measurement in all mechanically-ventilated patients as cuff pressure is found to be high in most of the patients admitted to intensive care unit. Complications of overinflation and underinflation can only be prevented if the acceptable cuff pressures are achieved.

  10. COMPARISON OF HIGH-DEFINITION OSCILLOMETRIC AND DIRECT ARTERIAL BLOOD PRESSURE MEASUREMENT IN ANESTHETIZED CHEETAHS (ACINONYX JUBATUS).

    Science.gov (United States)

    Sant Cassia, Emma V; Boswood, Adrian; Tordiffe, Adrian S W

    2015-09-01

    Blood pressure measurement reveals important insights into the health of conscious and anesthetized individuals. This is of particular interest in cheetahs (Acinonyx jubatus), which in captivity are known to suffer from chronic diseases that may be associated with hypertension and which often require immobilization for transport or veterinary treatment. Invasive testing methods are considered the gold standard but are not practical in many settings. Consequently, it is important to evaluate the use of noninvasive methods in this species. Measurements for systolic, diastolic, and mean arterial pressure obtained using high-definition oscillometry (HDO) at the coccygeal artery were compared to simultaneous direct measurements obtained via catheterization of the femoral or dorsal pedal artery in eight anesthetized captive cheetahs during nine anesthetic events. Overall, HDO and direct measurements agreed most closely for mean arterial pressure, and the poorest agreement was observed for systolic pressure. There was a tendency for low diastolic pressures to be underestimated and for high diastolic pressures to be overestimated. Across all three parameters, HDO measurements from the tail overestimated directly measured pressures in the femoral artery and underestimated those in the dorsal pedal artery. HDO agreed most closely with directly measured dorsal pedal pressures. Mean arterial pressure showed the greatest precision (standard deviation of 10.2 mm Hg) and lowest bias (-1.2 mm Hg), with 75.9% of readings within 10 mm Hg of the direct dorsal pedal pressure. Agreement with systolic pressure was hindered by a high bias (-10.4 mm Hg), but if a correction factor of +10 mm Hg was applied to all systolic measurements, agreement was improved and 65.7% of readings were within 10 mm Hg of the direct pressure. When compared to criteria defined by the American College of Veterinary Internal Medicine for validation of blood pressure devices, results were favorable, but a

  11. Measurement and analysis for optical radiation of glow discharge plasma at atmospheric pressure

    Science.gov (United States)

    Ren, Qinglei; Lin, Qi

    2006-02-01

    The optical radiation measurement and analysis to the glow discharge plasma at atmospheric pressure have been done in the paper. The low temperature plasma due to atmospheric pressure glow discharge (APGD) in air has been produced on the planar surface of designed electrode plate. The optical radiation spectra of the plasma produced in two kinds of electrode plats with different power values loaded have been measured and sampled with the minitype grating spectrograph system. The acquired spectra data are processed averagely and analyzed. The results of analysis indicate that the optical characteristic of the APGD plasma is related to the loaded power and layout of the electrode plate. This shows that it is feasible to describe the characteristic parameters of APGD plasma qualitatively and control the strength of the APGD plasma quantitatively by the obtained relationship, which provides a convenient approach for utilizing APGD plasma effectively and also establishes some foundation to investigate APGD plasma further.

  12. Measurements of Ion and Neutral Fluctuation Changes with Pressure in a Large-Scale Helicon Plasma

    Science.gov (United States)

    Dwyer, R. H.; Fisher, D. M.; Kelly, R. F.; Hatch, M. W.; Gilmore, M.

    2017-10-01

    Neutral particle dynamics may play an important role both in laboratory plasmas and in the edge of magnetic fusion devices. However, studies of neutral dynamics in these plasmas have been limited to date. Here we report on a basic study of ion and neutral fluctuations as a function of background neutral gas pressure. These experiments have been conducted in helicon discharges in the HelCat (Helicon-Cathode) dual-source plasma device at the University of New Mexico. The goal is to measure changes in ion and neutral density fluctuations with pressure and to gain an improved understanding of plasma-neutral interactions. Langmuir probe, Ar-I LIF, and high-speed imaging measurements of the fluctuations will be presented. Supported by U.S. National Science Foundation Award 1500423 and The University of New Mexico School of Engineering.

  13. Soft-Matter Resistive Sensor for Measuring Shear and Pressure Stresses

    Science.gov (United States)

    Tepayotl-Ramirez, Daniel; Roberts, Peter; Majidi, Carmel

    2013-03-01

    Building on emerging paradigms in soft-matter electronics, we introduce liquid-phase electronic sensors that simultaneously measures elastic pressure and shear deformation. The sensors are com- posed of a sheet of elastomer that is embedded with fluidic channels containing eutectic Gallium- Indium (EGaIn), a metal alloy that is liquid at room temperature. Applying pressure or shear traction to the surface of the surrounding elastomer causes the elastomer to elastically deform and changes the geometry and electrical properties of the embedded liquid-phase circuit elements. We introduce analytic models that predict the electrical response of the sensor to prescribed surface tractions. These models are validated with both Finite Element Analysis (FEA) and experimental measurements.

  14. Non-invasive blood pressure measurement in ferrets (Mustela putorius furo) using high definition oscillometry.

    Science.gov (United States)

    van Zeeland, Y R A; Wilde, A; Bosman, I H; Uilenreef, J J; Egner, B; Schoemaker, N J

    2017-10-01

    This study was conducted to validate the use of high definition oscillometry (HDO) for non-invasive blood pressure (NIBP) measurements in ferrets and to establish reference ranges for NIBP in minimally sedated, healthy, young adult ferrets (170mmHg) conditions. Although HDO correlated well with DABP (r>0.90), it showed significant proportional bias, whereby HDO generally underestimated DABP with hyper- and normotensive conditions, and overestimated DABP with hypotensive conditions. Measurements obtained from the hind limb showed higher bias than those obtained from the tail or forelimb (Pyoung adult ferrets were established at 95-155mmHg (systolic), 69-109mmHg (mean) and 51-87mmHg (diastolic) arterial pressures. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Density measurements under pressure for the binary system (ethanol plus methylcyclohexane)

    DEFF Research Database (Denmark)

    Zeberg-Mikkelsen, Claus Kjær; Lugo, L.; Fernandez, J.

    2005-01-01

    and influence of temperature, pressure and composition on the excess molar volume, the isothermal compressibility, and the isobaric thermal expansion, revealing that a volume expansion occurs for this binary system. The results have been interpreted as due to changes in the intermolecular distances or free......The density of the asymmetrical binary system composed of ethanol and methylcyclohexane has been measured under pressure using a vibrating tube densimeter. The measurements have been performed for eight different compositions as well as the pure compounds at eight temperatures in the range 283.15 K......-volume, disruption of the order molecular structure and the breaking of hydrogen bonds within the self-associating alcohol. (c) 2005 Elsevier Ltd. All rights reserved....

  16. Successive measurements of streaming potential and electroosmotic pressure with the same core-holder

    Science.gov (United States)

    Yin, Chenggang; Hu, Hengshan; Yu, Chunhao; Wang, Jun

    2018-05-01

    Successive measurements of the streaming potential and electroosmotic pressure of each core sample are important for understanding the mechanisms of electrokinetic effects. In previous studies, one plug of the core-holder needs to be replaced in these two experiments, which causes the change of the fluid parameters and the boundary conditions in the core. We design a new core-holder to permit successive experiments without plug replacement, which ensures the consistency of the measurement environment. A two-direction harmonic pressure-driving source is accordingly designed. Using this new equipment, electrokinetic experiments conducted ten core samples at 0.4 mol/L NaCl solution. The results show good agreement between the electrokinetically deduced permeability and premeasured gas permeability. For high salinity saturated samples, the permeability can be inverted from electroosmotic effect instead of the streaming potential.

  17. Using internal jugular pulsations as a manometer for right atrial pressure measurements.

    Science.gov (United States)

    Constant, J

    2000-01-01

    External jugulars are not reliable as an indication of right atrial pressure because of their passage through two right angles and also because they are often not visible. The top level of internal jugular pulsations which are transmitted to the skin of the neck serves as a pulsation manometer. A standard chest angle of 45 degrees and a standard zero at the sternal angle can be used together with a centimeter ruler to give a useful measurement of jugular venous pressure. The use of a carpenter level (spirit level) and a round-bottomed tongue blade measured off in centimeters will allow accurate follow-up. An increase in tone-volume can be detected by the abdominal compression test or abdominojugular test (also known by the outdated terminology of hepatojugular reflux). Copyright 2000 S. Karger AG, Basel

  18. Fast diffuse correlation spectroscopy (DCS) for non-invasive measurement of intracranial pressure (ICP) (Conference Presentation)

    Science.gov (United States)

    Farzam, Parisa; Sutin, Jason; Wu, Kuan-Cheng; Zimmermann, Bernhard B.; Tamborini, Davide; Dubb, Jay; Boas, David A.; Franceschini, Maria Angela

    2017-02-01

    Intracranial pressure (ICP) monitoring has a key role in the management of neurosurgical and neurological injuries. Currently, the standard clinical monitoring of ICP requires an invasive transducer into the parenchymal tissue or the brain ventricle, with possibility of complications such as hemorrhage and infection. A non-invasive method for measuring ICP, would be highly preferable, as it would allow clinicians to promptly monitor ICP during transport and allow for monitoring in a larger number of patients. We have introduced diffuse correlation spectroscopy (DCS) as a non-invasive ICP monitor by fast measurement of pulsatile cerebral blood flow (CBF). The method is similar to Transcranial Doppler ultrasound (TCD), which derives ICP from the amplitude of the pulsatile cerebral blood flow velocity, with respect to the amplitude of the pulsatile arterial blood pressure. We believe DCS measurement is superior indicator of ICP than TCD estimation because DCS directly measures blood flow, not blood flow velocity, and the small cortical vessels measured by DCS are more susceptible to transmural pressure changes than the large vessels. For fast DCS measurements to recover pulsatile CBF we have developed a custom high-power long-coherent laser and a strategy for delivering it to the tissue within ANSI standards. We have also developed a custom FPGA-based correlator board, which facilitates DCS data acquisitions at 50-100 Hz. We have tested the feasibility of measuring pulsatile CBF and deriving ICP in two challenging scenarios: humans and rats. SNR is low in human adults due to large optode distances. It is similarly low in rats because the fast heart rate in this setting requires a high repetition rate.

  19. Between-day reliability of centre of pressure measures for balance assessment in hemiplegic stroke patients.

    OpenAIRE

    Gasq , David; Labrunée , Marc; Amarantini , David; Dupui , Philippe; Montoya , Richard; Marque , Philippe

    2014-01-01

    International audience; BACKGROUND: Stroke patients have impaired postural balance that increases the risk of falls and impairs their mobility. Assessment of postural balance is commonly carried out by recording centre of pressure (CoP) displacements, but the lack of data concerning reliability of these measures compromises their interpretation. The purpose of this study was to investigate the between-day reliability of six CoP-based variables, in order to provide i) reliability data for moni...

  20. Advanced Liquid-Free, Piezoresistive, SOI-Based Pressure Sensors for Measurements in Harsh Environments

    Directory of Open Access Journals (Sweden)

    Ha-Duong Ngo

    2015-08-01

    Full Text Available In this paper we present and discuss two innovative liquid-free SOI sensors for pressure measurements in harsh environments. The sensors are capable of measuring pressures at high temperatures. In both concepts media separation is realized using a steel membrane. The two concepts represent two different strategies for packaging of devices for use in harsh environments and at high temperatures. The first one is a “one-sensor-one-packaging_technology” concept. The second one uses a standard flip-chip bonding technique. The first sensor is a “floating-concept”, capable of measuring pressures at temperatures up to 400 °C (constant load with an accuracy of 0.25% Full Scale Output (FSO. A push rod (mounted onto the steel membrane transfers the applied pressure directly to the center-boss membrane of the SOI-chip, which is placed on a ceramic carrier. The chip membrane is realized by Deep Reactive Ion Etching (DRIE or Bosch Process. A novel propertied chip housing employing a sliding sensor chip that is fixed during packaging by mechanical preloading via the push rod is used, thereby avoiding chip movement, and ensuring optimal push rod load transmission. The second sensor can be used up to 350 °C. The SOI chips consists of a beam with an integrated centre-boss with was realized using KOH structuring and DRIE. The SOI chip is not “floating” but bonded by using flip-chip technology. The fabricated SOI sensor chip has a bridge resistance of 3250 Ω. The realized sensor chip has a sensitivity of 18 mV/µm measured using a bridge current of 1 mA.