Newly discovered Late Triassic Baqing eclogite in central Tibet indicates an anticlockwise West-East Qiangtang collision.

PubMed

Zhang, Yu-Xiu; Jin, Xin; Zhang, Kai-Jun; Sun, Wei-Dong; Liu, Jian-Ming; Zhou, Xiao-Yao; Yan, Li-Long

2018-01-17

The Triassic eclogite-bearing central Qiangtang metamorphic belt (CQMB) in the northern Tibetan Plateau has been debated whether it is a metamorphic core complex underthrust from the Jinsha Paleo-Tethys or an in-situ Shuanghu suture. The CQMB is thus a key issue to elucidate the crustal architecture of the northern Tibetan Plateau, the tectonics of the eastern Tethys, and the petrogenesis of Cenozoic high-K magmatism. We here report the newly discovered Baqing eclogite along the eastern extension of the CQMB near the Baqing town, central Tibet. These eclogites are characterized by the garnet + omphacite + rutile + phengite + quartz assemblages. Primary eclogite-facies metamorphic pressure-temperature estimates yield consistent minimum pressure of 25 ± 1 kbar at 730 ± 60 °C. U-Pb dating on zircons that contain inclusions (garnet + omphacite + rutile + phengite) gave eclogite-facies metamorphic ages of 223 Ma. The geochemical continental crustal signature and the presence of Paleozoic cores in the zircons indicate that the Baqing eclogite formed by continental subduction and marks an eastward-younging anticlockwise West-East Qiangtang collision along the Shuanghu suture from the Middle to Late Triassic.

Studies on droplet evaporation and combustion in high pressures

NASA Technical Reports Server (NTRS)

Sato, J.

1993-01-01

High pressure droplet evaporation and combustion have been studied up to 15 MPa under normal and microgravity fields. From the evaporation studies, it has been found that in the supercritical environments, the droplet evaporation rate and lifetime take a maximum and a minimum at an ambient pressure over the critical pressure. Its maximum and minimum points move toward the lower ambient pressures if the ambient temperature is increased. It has been found from the combustion studies that the burning life time takes a minimum at an ambient pressure being equal to the critical pressure. It is attributable to both the pressure dependency of the diffusion rate and the droplet evaporation characteristics described above.

Noninductively Driven Tokamak Plasmas at Near-Unity Toroidal Beta

DOE PAGES

Schlossberg, David J.; Bodner, Grant M.; Bongard, Michael W.; ...

2017-07-01

Access to and characterization of sustained, toroidally confined plasmas with a very high plasma-to-magnetic pressure ratio (β t), low internal inductance, high elongation, and nonsolenoidal current drive is a central goal of present tokamak plasma research. Stable access to this desirable parameter space is demonstrated in plasmas with ultralow aspect ratio and high elongation. Local helicity injection provides nonsolenoidal sustainment, low internal inductance, and ion heating. Equilibrium analyses indicate β t up to ~100% with a minimum |B| well spanning up to ~50% of the plasma volume.

Noninductively Driven Tokamak Plasmas at Near-Unity Toroidal Beta.

PubMed

Schlossberg, D J; Bodner, G M; Bongard, M W; Burke, M G; Fonck, R J; Perry, J M; Reusch, J A

2017-07-21

Access to and characterization of sustained, toroidally confined plasmas with a very high plasma-to-magnetic pressure ratio (β_{t}), low internal inductance, high elongation, and nonsolenoidal current drive is a central goal of present tokamak plasma research. Stable access to this desirable parameter space is demonstrated in plasmas with ultralow aspect ratio and high elongation. Local helicity injection provides nonsolenoidal sustainment, low internal inductance, and ion heating. Equilibrium analyses indicate β_{t} up to ∼100% with a minimum |B| well spanning up to ∼50% of the plasma volume.

Curved butterfly bileaflet prosthetic cardiac valve

DOEpatents

McQueen, David M.; Peskin, Charles S.

1991-06-25

An annular valve body having a central passageway for the flow of blood therethrough with two curved leaflets each of which is pivotally supported on an accentric positioned axis in the central passageway for moving between a closed position and an open position. The leaflets are curved in a plane normal to the eccentric axis and positioned with the convex side of the leaflets facing each other when the leaflets are in the open position. Various parameters such as the curvature of the leaflets, the location of the eccentric axis, and the maximum opening angle of the leaflets are optimized according to the following performance criteria: maximize the minimum peak velocity through the valve, maximize the net stroke volume, and minimize the mean forward pressure difference, thereby reducing thrombosis and improving the hemodynamic performance.

Using U-Th-Pb petrochronology to determine rates of ductile thrusting: Time windows into the Main Central Thrust, Sikkim Himalaya

NASA Astrophysics Data System (ADS)

Mottram, Catherine M.; Parrish, Randall R.; Regis, Daniele; Warren, Clare J.; Argles, Tom W.; Harris, Nigel B. W.; Roberts, Nick M. W.

2015-07-01

Quantitative constraints on the rates of tectonic processes underpin our understanding of the mechanisms that form mountains. In the Sikkim Himalaya, late structural doming has revealed time-transgressive evidence of metamorphism and thrusting that permit calculation of the minimum rate of movement on a major ductile fault zone, the Main Central Thrust (MCT), by a novel methodology. U-Th-Pb monazite ages, compositions, and metamorphic pressure-temperature determinations from rocks directly beneath the MCT reveal that samples from 50 km along the transport direction of the thrust experienced similar prograde, peak, and retrograde metamorphic conditions at different times. In the southern, frontal edge of the thrust zone, the rocks were buried to conditions of 550°C and 0.8 GPa between 21 and 18 Ma along the prograde path. Peak metamorphic conditions of 650°C and 0.8-1.0 GPa were subsequently reached as this footwall material was underplated to the hanging wall at 17-14 Ma. This same process occurred at analogous metamorphic conditions between 18-16 Ma and 14.5-13 Ma in the midsection of the thrust zone and between 13 Ma and 12 Ma in the northern, rear edge of the thrust zone. Northward younging muscovite 40Ar/39Ar ages are consistently 4 Ma younger than the youngest monazite ages for equivalent samples. By combining the geochronological data with the >50 km minimum distance separating samples along the transport axis, a minimum average thrusting rate of 10 ± 3 mm yr-1 can be calculated. This provides a minimum constraint on the amount of Miocene India-Asia convergence that was accommodated along the MCT.

Magnetic Resonance Imaging of Optic Nerve Traction During Adduction in Primary Open-Angle Glaucoma With Normal Intraocular Pressure

PubMed Central

Demer, Joseph L.; Clark, Robert A.; Suh, Soh Youn; Giaconi, JoAnn A.; Nouri-Mahdavi, Kouros; Law, Simon K.; Bonelli, Laura; Coleman, Anne L.; Caprioli, Joseph

2017-01-01

Purpose We used magnetic resonance imaging (MRI) to ascertain effects of optic nerve (ON) traction in adduction, a phenomenon proposed as neuropathic in primary open-angle glaucoma (POAG). Methods Seventeen patients with POAG and maximal IOP ≤ 20 mm Hg, and 31 controls underwent MRI in central gaze and 20° to 30° abduction and adduction. Optic nerve and sheath area centroids permitted computation of midorbital lengths versus minimum paths. Results Average mean deviation (±SEM) was −8.2 ± 1.2 dB in the 15 patients with POAG having interpretable perimetry. In central gaze, ON path length in POAG was significantly more redundant (104.5 ± 0.4% of geometric minimum) than in controls (102.9 ± 0.4%, P = 2.96 × 10−4). In both groups the ON became significantly straighter in adduction (28.6 ± 0.8° in POAG, 26.8 ± 1.1° in controls) than central gaze and abduction. In adduction, the ON in POAG straightened to 102.0% ± 0.2% of minimum path length versus 104.5% ± 0.4% in central gaze (P = 5.7 × 10−7), compared with controls who straightened to 101.6% ± 0.1% from 102.9% ± 0.3% in central gaze (P = 8.7 × 10−6); and globes retracted 0.73 ± 0.09 mm in POAG, but only 0.07 ± 0.08 mm in controls (P = 8.8 × 10−7). Both effects were confirmed in age-matched controls, and remained significant after correction for significant effects of age and axial globe length (P = 0.005). Conclusions Although tethering and elongation of ON and sheath are normal in adduction, adduction is associated with abnormally great globe retraction in POAG without elevated IOP. Traction in adduction may cause mechanical overloading of the ON head and peripapillary sclera, thus contributing to or resulting from the optic neuropathy of glaucoma independent of IOP. PMID:28829843

Passive blast pressure sensor

DOEpatents

King, Michael J.; Sanchez, Roberto J.; Moss, William C.

2013-03-19

A passive blast pressure sensor for detecting blast overpressures of at least a predetermined minimum threshold pressure. The blast pressure sensor includes a piston-cylinder arrangement with one end of the piston having a detection surface exposed to a blast event monitored medium through one end of the cylinder and the other end of the piston having a striker surface positioned to impact a contact stress sensitive film that is positioned against a strike surface of a rigid body, such as a backing plate. The contact stress sensitive film is of a type which changes color in response to at least a predetermined minimum contact stress which is defined as a product of the predetermined minimum threshold pressure and an amplification factor of the piston. In this manner, a color change in the film arising from impact of the piston accelerated by a blast event provides visual indication that a blast overpressure encountered from the blast event was not less than the predetermined minimum threshold pressure.

Heat waves and jet stream relations - nature of dry and wet shifts around the 2.8 kyr BP event in Central Europe

NASA Astrophysics Data System (ADS)

Slowinski, M. M.; Persoiu, A.; Slowinska, S.; Marcisz, K.; Ionita, M.; Lamentowicz, M.

2017-12-01

Solar insolation was the main driver of N Hemisphere storm tracks changes, with significant impacts on European climate variability during the Holocene. Consequently, the Homeric solar minimum, which occurred between 2,750 and 2,550 cal BP, was characterized by cooling and increase in wind strength and humidity in W Europe. In contrast, environmental reconstructions from Central and E Europe show that the climatic changes during this period were often more complex, with increased hydrological instability and a shift towards drier conditions. These contrasting conditions could be explained by the blocking in a stationary position of a high-pressure system above Central and E Europe as a result of the behavior of the jet stream. In order to understand how these changes in the behavior of the jet stream were acting in the past, we have analyzed a modern analogue to better understand the climatic map of Europe during the Homeric minimum of the 9th century BC. Thus, in summer 2015, a northward extending meander of the jet stream led to dry and hot conditions in C Europe, blocking the transport of Atlantic-sourced moisture eastwards and leading to increased precipitation in W Europe. Contrary, in 2013, the position of the high-pressure cells associated with the meandering of the jet-stream was located over W Russia and E Europe (both affected by heat waves resulting from meridional advection of dry/hot air), leading to more Rossby waves breaking over C Europe and delivering record amounts of precipitation. To test whether a similar mechanism could act on longer times scales, we have analyzed two high-resolution palaeoclimate datasets from E Europe (Rąbień peatbog, Poland and Scăriloara Ice Cave, Romania), located in areas with both N Atlantic and Mediterranean climatic influences. At the time of the Homeric Solar Minimum, warm climatic conditions dominated in SE Europe, with advection of warm and dry air from the Mediterranean. W Europe was rather wet around that time and these contrasting conditions could have been the result of blocking conditions over C Europe, induced by a solar-influenced strongly meandering jet-stream. Our recent monitoring observation and paleoclimate data support studies that presents link between arctic polar vortex, jet streams, sea-ice formation in the Arctic and climate variability in Europe.

Firefighter's compressed air breathing system pressure vessel development program

NASA Technical Reports Server (NTRS)

Beck, E. J.

1974-01-01

The research to design, fabricate, test, and deliver a pressure vessel for the main component in an improved high-performance firefighter's breathing system is reported. The principal physical and performance characteristics of the vessel which were required are: (1) maximum weight of 9.0 lb; (2) maximum operating pressure of 4500 psig (charge pressure of 4000 psig); (3) minimum contained volume of 280 in. 3; (4) proof pressure of 6750 psig; (5) minimum burst pressure of 9000 psig following operational and service life; and (6) a minimum service life of 15 years. The vessel developed to fulfill the requirements described was completely sucessful, i.e., every category of performence was satisfied. The average weight of the vessel was found to be about 8.3 lb, well below the 9.0 lb specification requirement.

The surface climatology of the Ross Ice Shelf Antarctica.

PubMed

Costanza, Carol A; Lazzara, Matthew A; Keller, Linda M; Cassano, John J

2016-12-01

The University of Wisconsin-Madison Antarctic Automatic Weather Station (AWS) project has been making meteorological surface observations on the Ross Ice Shelf (RIS) for approximately 30 years. This network offers the most continuous set of routine measurements of surface meteorological variables in this region. The Ross Island area is excluded from this study. The surface climate of the RIS is described using the AWS measurements. Temperature, pressure, and wind data are analysed on daily, monthly, seasonal, and annual time periods for 13 AWS across the RIS. The AWS are separated into three representative regions - central, coastal, and the area along the Transantarctic Mountains - in order to describe specific characteristics of sections of the RIS. The climatology describes general characteristics of the region and significant changes over time. The central AWS experiences the coldest mean temperature, and the lowest resultant wind speed. These AWSs also experience the coldest potential temperatures with a minimum of 209.3 K at Gill AWS. The AWS along the Transantarctic Mountains experiences the warmest mean temperature, the highest mean sea-level pressure, and the highest mean resultant wind speed. Finally, the coastal AWS experiences the lowest mean pressure. Climate indices (MEI, SAM, and SAO) are compared to temperature and pressure data of four of the AWS with the longest observation periods, and significant correlation is found for most AWS in sea-level pressure and temperature. This climatology study highlights characteristics that influence the climate of the RIS, and the challenges of maintaining a long-term Antarctic AWS network. Results from this effort are essential for the broader Antarctic meteorology community for future research.

Dynamics of particles in central Encke ringlet

NASA Astrophysics Data System (ADS)

Sun, K.-L.; Spahn, F.; Schmidt, J.

2012-09-01

The Encke gap is a 320 km wide division in the Saturn A ring centered at 133,581 km. There are at least 3 ringlets in Encke gap, and the central one shares the orbit with Pan [1]. Observations suggest that these ringlets are mainly composed of micronsized particles [2]. The lifetime of these particles are restricted, mechanisms must be at work to replenish these ringlets. The kinetic balance of dust production, dynamical evolution, and loss of dust has been investigated in [3]. In this work, we focus on the particle dynamics in the Encke gap. Our results show that in the central Encke ringlet: (1) The solar radiation pressure provides a minimum particle radius of 7μm; (2) The plasma drag force pushes particle outward in a rate of ˜ 1km/yr; (3) Particles are in a 'modified' horseshoe orbit which is the result of horseshoe orbit plus plasma drag, this orbit prevent particles to reach large co-rotational longitudes of Pan.

Minimum Period of Rotation of Millisecond Pulsars and Pulsar Matter Equations of State

NASA Astrophysics Data System (ADS)

Mikheev, Sergey; Tsvetkov, Victor

2018-02-01

Based on the findings of our previous studies of fast-rotating Newtonian polytropes, we found the relation between the minimum pulsar rotation period, the value of pulsar central density, and the polytropic index. From this relation we come to the conclusion that the value of minimum central density of a pulsar with a peak period is 2.5088 • 1014 g/cm3.

49 CFR 178.44 - Specification 3HT seamless steel cylinders for aircraft use.

Code of Federal Regulations, 2011 CFR

2011-10-01

... with a water capacity (nominal) of not over 150 pounds and a service pressure of at least 900 psig. (b...., should be held to a minimum consistent with good high stress pressure vessel manufacturing practices. If... wall thickness must be such that the wall stress at the minimum specified test pressure may not exceed...

46 CFR 162.028-3 - Requirements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... which are subjected to pressure, exclusive of the hose, shall be at least five times the maximum working... which will withstand a minimum bursting pressure of 6,000 p.s.i., and a discharge hose or tube which will withstand a minimum bursting pressure of 5,000 p.s.i. The hose shall be constructed with either a...

46 CFR 162.028-3 - Requirements.

Code of Federal Regulations, 2014 CFR

2014-10-01

... which are subjected to pressure, exclusive of the hose, shall be at least five times the maximum working... which will withstand a minimum bursting pressure of 6,000 p.s.i., and a discharge hose or tube which will withstand a minimum bursting pressure of 5,000 p.s.i. The hose shall be constructed with either a...

46 CFR 162.028-3 - Requirements.

Code of Federal Regulations, 2013 CFR

2013-10-01

... which are subjected to pressure, exclusive of the hose, shall be at least five times the maximum working... which will withstand a minimum bursting pressure of 6,000 p.s.i., and a discharge hose or tube which will withstand a minimum bursting pressure of 5,000 p.s.i. The hose shall be constructed with either a...

Impact of parameterization of physical processes on simulation of track and intensity of tropical cyclone Nargis (2008) with WRF-NMM model.

PubMed

Pattanayak, Sujata; Mohanty, U C; Osuri, Krishna K

2012-01-01

The present study is carried out to investigate the performance of different cumulus convection, planetary boundary layer, land surface processes, and microphysics parameterization schemes in the simulation of a very severe cyclonic storm (VSCS) Nargis (2008), developed in the central Bay of Bengal on 27 April 2008. For this purpose, the nonhydrostatic mesoscale model (NMM) dynamic core of weather research and forecasting (WRF) system is used. Model-simulated track positions and intensity in terms of minimum central mean sea level pressure (MSLP), maximum surface wind (10 m), and precipitation are verified with observations as provided by the India Meteorological Department (IMD) and Tropical Rainfall Measurement Mission (TRMM). The estimated optimum combination is reinvestigated with six different initial conditions of the same case to have better conclusion on the performance of WRF-NMM. A few more diagnostic fields like vertical velocity, vorticity, and heat fluxes are also evaluated. The results indicate that cumulus convection play an important role in the movement of the cyclone, and PBL has a crucial role in the intensification of the storm. The combination of Simplified Arakawa Schubert (SAS) convection, Yonsei University (YSU) PBL, NMM land surface, and Ferrier microphysics parameterization schemes in WRF-NMM give better track and intensity forecast with minimum vector displacement error.

Developing a pressure ulcer risk factor minimum data set and risk assessment framework.

PubMed

Coleman, Susanne; Nelson, E Andrea; Keen, Justin; Wilson, Lyn; McGinnis, Elizabeth; Dealey, Carol; Stubbs, Nikki; Muir, Delia; Farrin, Amanda; Dowding, Dawn; Schols, Jos M G A; Cuddigan, Janet; Berlowitz, Dan; Jude, Edward; Vowden, Peter; Bader, Dan L; Gefen, Amit; Oomens, Cees W J; Schoonhoven, Lisette; Nixon, Jane

2014-10-01

To agree a draft pressure ulcer risk factor Minimum Data Set to underpin the development of a new evidenced-based Risk Assessment Framework. A recent systematic review identified the need for a pressure ulcer risk factor Minimum Data Set and development and validation of an evidenced-based pressure ulcer Risk Assessment Framework. This was undertaken through the Pressure UlceR Programme Of reSEarch (RP-PG-0407-10056), funded by the National Institute for Health Research and incorporates five phases. This article reports phase two, a consensus study. Consensus study. A modified nominal group technique based on the Research and Development/University of California at Los Angeles appropriateness method. This incorporated an expert group, review of the evidence and the views of a Patient and Public Involvement service user group. Data were collected December 2010-December 2011. The risk factors and assessment items of the Minimum Data Set (including immobility, pressure ulcer and skin status, perfusion, diabetes, skin moisture, sensory perception and nutrition) were agreed. In addition, a draft Risk Assessment Framework incorporating all Minimum Data Set items was developed, comprising a two stage assessment process (screening and detailed full assessment) and decision pathways. The draft Risk Assessment Framework will undergo further design and pre-testing with clinical nurses to assess and improve its usability. It will then be evaluated in clinical practice to assess its validity and reliability. The Minimum Data Set could be used in future for large scale risk factor studies informing refinement of the Risk Assessment Framework. © 2014 The Authors. Journal of Advanced Nursing Published by John Wiley & Sons Ltd.

The pharmacological effects of intramuscular administration of alfaxalone combined with medetomidine and butorphanol in dogs.

PubMed

Tamura, Jun; Hatakeyama, Naohiro; Ishizuka, Tomohito; Itami, Takaharu; Fukui, Sho; Miyoshi, Kenjiro; Sano, Tadashi; Pasloske, Kirby; Yamashita, Kazuto

2016-07-01

The pharmacological effects of intramuscular (IM) administration of alfaxalone combined with medetomidine and butorphanol were evaluated in 6 healthy beagle dogs. Each dog received three treatments with a minimum 10-day interval between treatments. The dogs received an IM injection of alfaxalone 2.5 mg/kg (ALFX), medetomidine 2.5 µg/kg and butorphanol 0.25 mg/kg (MB), or their combination (MBA) 1 hr after the recovery from their instrumentation. Endotracheal intubation was attempted, and dogs were allowed to breath room air. Neuro-depressive effects (behavior changes and subjective scores) and cardiorespiratory parameters (rectal temperature, heart rate, respiratory rate, direct blood pressure, central venous pressure and blood gases) were evaluated before and at 2 to 120 min after IM treatment. Each dog became lateral recumbency, except for two dogs administered the MB treatment. The duration was longer in the MBA treatment compared with the ALFX treatment (100 ± 48 min vs 46 ± 13 min). Maintenance of the endotracheal tube lasted for 60 ± 24 min in five dogs administered the MBA treatment and for 20 min in one dog administered the ALFX treatment. Cardiorespiratory variables were maintained within clinically acceptable ranges, although decreases in heart and respiratory rates, and increases in central venous pressure occurred after the MBA and MB treatments. The MBA treatment provided an anesthetic effect that permitted endotracheal intubation without severe cardiorespiratory depression in healthy dogs.

Airfoil profiles for minimum pressure drag at supersonic velocities -- general analysis with application to linearized supersonic flow

NASA Technical Reports Server (NTRS)

Chapman, Dean R

1952-01-01

A theoretical investigation is made of the airfoil profile for minimum pressure drag at zero lift in supersonic flow. In the first part of the report a general method is developed for calculating the profile having the least pressure drag for a given auxiliary condition, such as a given structural requirement or a given thickness ratio. The various structural requirements considered include bending strength, bending stiffness, torsional strength, and torsional stiffness. No assumption is made regarding the trailing-edge thickness; the optimum value is determined in the calculations as a function of the base pressure. To illustrate the general method, the optimum airfoil, defined as the airfoil having minimum pressure drag for a given auxiliary condition, is calculated in a second part of the report using the equations of linearized supersonic flow.

The surface climatology of the Ross Ice Shelf Antarctica

PubMed Central

Lazzara, Matthew A.; Keller, Linda M.; Cassano, John J.

2016-01-01

ABSTRACT The University of Wisconsin‐Madison Antarctic Automatic Weather Station (AWS) project has been making meteorological surface observations on the Ross Ice Shelf (RIS) for approximately 30 years. This network offers the most continuous set of routine measurements of surface meteorological variables in this region. The Ross Island area is excluded from this study. The surface climate of the RIS is described using the AWS measurements. Temperature, pressure, and wind data are analysed on daily, monthly, seasonal, and annual time periods for 13 AWS across the RIS. The AWS are separated into three representative regions – central, coastal, and the area along the Transantarctic Mountains – in order to describe specific characteristics of sections of the RIS. The climatology describes general characteristics of the region and significant changes over time. The central AWS experiences the coldest mean temperature, and the lowest resultant wind speed. These AWSs also experience the coldest potential temperatures with a minimum of 209.3 K at Gill AWS. The AWS along the Transantarctic Mountains experiences the warmest mean temperature, the highest mean sea‐level pressure, and the highest mean resultant wind speed. Finally, the coastal AWS experiences the lowest mean pressure. Climate indices (MEI, SAM, and SAO) are compared to temperature and pressure data of four of the AWS with the longest observation periods, and significant correlation is found for most AWS in sea‐level pressure and temperature. This climatology study highlights characteristics that influence the climate of the RIS, and the challenges of maintaining a long‐term Antarctic AWS network. Results from this effort are essential for the broader Antarctic meteorology community for future research. PMID:28008213

Cosmic Ray Hits in the Central Nervous System at Solar Maximum

NASA Technical Reports Server (NTRS)

Curtis, S. B.; Vazquez, M. E.; Wilson, J. W.; Kim, M.-H. Y.

1997-01-01

It has been suggested that a manned mission to Mars be launched at solar maximum rather than at solar minimum to minimize the radiation exposure to galactic cosmic rays. It is true that the number of hits from highly ionizing particles to critical regions in the brain will be less at solar maximum, and it is of some interest to estimate how much less. We present here calculations for several sites within the brain from iron ions (z = 26) and from particles with charge, z, greater than or equal to 15. The same shielding configurations and sites in the brain used in an earlier paper for solar minimum are employed so that direct comparison of results between the two solar activity conditions can be made. A simple pressure-vessel wall and an equipment room onboard a spacecraft are chosen as shielding examples. In the equipment room, typical results for the thalamus (100 mm2 area) are that the probability of any given cell nucleus being hit decreases from 10 percent at solar minimum to 6 percent at solar maximum for particles with z greater than or equal to 15 and from 2.3 percent to 1.3 percent for iron ions. We conclude that this modest decrease in hit frequency (less than a factor of two) is not a compelling reason to avoid solar minimum for a manned mission to Mars.

All APAPs Are Not Equivalent for the Treatment of Sleep Disordered Breathing: A Bench Evaluation of Eleven Commercially Available Devices.

PubMed

Zhu, Kaixian; Roisman, Gabriel; Aouf, Sami; Escourrou, Pierre

2015-07-15

This study challenged on a bench-test the efficacy of auto-titrating positive airway pressure (APAP) devices for obstructive sleep disordered breathing treatment and evaluated the accuracy of the device reports. Our bench consisted of an active lung simulator and a Starling resistor. Eleven commercially available APAP devices were evaluated on their reactions to single-type SDB sequences (obstructive apnea and hypopnea, central apnea, and snoring), and to a long general breathing scenario (5.75 h) simulating various SDB during four sleep cycles and to a short scenario (95 min) simulating one sleep cycle. In the single-type sequence of 30-minute repetitive obstructive apneas, only 5 devices normalized the airflow (> 70% of baseline breathing amplitude). Similarly, normalized breathing was recorded with 8 devices only for a 20-min obstructive hypopnea sequence. Five devices increased the pressure in response to snoring. Only 4 devices maintained a constant minimum pressure when subjected to repeated central apneas with an open upper airway. In the long general breathing scenario, the pressure responses and the treatment efficacy differed among devices: only 5 devices obtained a residual obstructive AHI < 5/h. During the short general breathing scenario, only 2 devices reached the same treatment efficacy (p < 0.001), and 3 devices underestimated the AHI by > 10% (p < 0.001). The long scenario led to more consistent device reports. Large differences between APAP devices in the treatment efficacy and the accuracy of report were evidenced in the current study. © 2015 American Academy of Sleep Medicine.

Central blood pressure and chronic kidney disease

PubMed Central

Ohno, Yoichi; Kanno, Yoshihiko; Takenaka, Tsuneo

2016-01-01

In this review, we focused on the relationship between central blood pressure and chronic kidney diseases (CKD). Wave reflection is a major mechanism that determines central blood pressure in patients with CKD. Recent medical technology advances have enabled non-invasive central blood pressure measurements. Clinical trials have demonstrated that compared with brachial blood pressure, central blood pressure is a stronger risk factor for cardiovascular (CV) and renal diseases. CKD is characterized by a diminished renal autoregulatory ability, an augmented direct transmission of systemic blood pressure to glomeruli, and an increase in proteinuria. Any elevation in central blood pressure accelerates CKD progression. In the kidney, interstitial inflammation induces oxidative stress to handle proteinuria. Oxidative stress facilitates atherogenesis, increases arterial stiffness and central blood pressure, and worsens the CV prognosis in patients with CKD. A vicious cycle exists between CKD and central blood pressure. To stop this cycle, vasodilator antihypertensive drugs and statins can reduce central blood pressure and oxidative stress. Even in early-stage CKD, mineral and bone disorders (MBD) may develop. MBD promotes oxidative stress, arteriosclerosis, and elevated central blood pressure in patients with CKD. Early intervention or prevention seems necessary to maintain vascular health in patients with CKD. PMID:26788468

Droplet squeezing through a narrow constriction: Minimum impulse and critical velocity

NASA Astrophysics Data System (ADS)

Zhang, Zhifeng; Drapaca, Corina; Chen, Xiaolin; Xu, Jie

2017-07-01

Models of a droplet passing through narrow constrictions have wide applications in science and engineering. In this paper, we report our findings on the minimum impulse (momentum change) of pushing a droplet through a narrow circular constriction. The existence of this minimum impulse is mathematically derived and numerically verified. The minimum impulse happens at a critical velocity when the time-averaged Young-Laplace pressure balances the total minor pressure loss in the constriction. Finally, numerical simulations are conducted to verify these concepts. These results could be relevant to problems of energy optimization and studies of chemical and biomedical systems.

Sediment sound velocities from Sonobuoys: Sunda Trench and forearc basins, Nicobar and Central Bengal Fans, and Andaman Sea Basins

NASA Astrophysics Data System (ADS)

Bachman, Richard T.; Hamilton, Edwin L.; Curray, Joseph R.

1983-11-01

Supplement is available with entire article on microfiche. Order from American Geophysical Union, 2000 Florida Avenue, N.W., Washington, DC 20009. Document B83-007; $2.50. Payment must accompany order. Measurements of mean sound velocities in the first, largely unlithified layers in the seafloor were made using the sonobuoy technique in several areas in the northern Indian Ocean. Older measurements were added to new measurements, and regressions for mean and instantaneous velocity versus one-way travel time of sound are presented for the central Bengal Fan, the central Andaman Sea Basin, the Nicobar Fan, and the Sunda Trench. New data and regression equations are presented for the Mergui-north Sumatra Basin and for four forearc basins between Sumatra and Java and the Sunda Trench. Minimum velocity gradients were found in those areas where sedimentation rates were high, and sediments have accumulated in thick sections which have not had time to fully consolidate (porosity in the top of the sediment section has not been fully reduced under overburden pressure). These minimum velocity gradients (just under the seafloor) were found in the four forearc basins where they ranged from 0.34 s-1 to 0.84 s-1 with an average of 0.58 s-1. The near-surface velocity gradient in the Sunda Trench was 1.33 s-1, but was higher in the adjacent, fossil Nicobar Fan (1.62 s-1). In the surface of the Bengal Fan the velocity gradient was low in the upper fan (0.86 s-1), high in the central fan (1.94 s-1), and again lower in the southern fan (1.18 s-1), which may support sedimentation models calling for bypassing of the central fan and higher rates of accumulation on the southern fan.

42 CFR 84.82 - Gas pressure gages; minimum requirements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Gas pressure gages; minimum requirements. 84.82 Section 84.82 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Self...

42 CFR 84.82 - Gas pressure gages; minimum requirements.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false Gas pressure gages; minimum requirements. 84.82 Section 84.82 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Self...

42 CFR 84.82 - Gas pressure gages; minimum requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Gas pressure gages; minimum requirements. 84.82 Section 84.82 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Self...

42 CFR 84.82 - Gas pressure gages; minimum requirements.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false Gas pressure gages; minimum requirements. 84.82 Section 84.82 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Self...

42 CFR 84.82 - Gas pressure gages; minimum requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Gas pressure gages; minimum requirements. 84.82 Section 84.82 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Self...

Cold Episodes, Their Precursors and Teleconnections in the Central Peruvian Andes (1958-2009)

NASA Astrophysics Data System (ADS)

Sulca, J. C.; Vuille, M. F.; Trasmonte, G.; Silva, Y.; Takahashi, K.

2014-12-01

The Mantaro valley (MV) is located in the central Peruvian Andes. Occasionally, cold episodes are observed during the austral summer (January-March), which strongly damage crops. However, little is known about the causes and impacts of such cold episodes in the MV. The main goal of this study is thus to characterize cold episodes in the MV and assess their large-scale circulation and teleconnections over South America (SA) during austral summer. To identify cold events in the MV daily minimum temperature for the period 1958-2009 from Huayao station, located within the MV was used. We defined a cold episode as the period when daily minimum temperature drops below the 10-percentile for at least one day. Several gridded reanalysis and satellite products were used to characterize the large-scale circulation, cloud cover and rainfall over SA associated with these events for same period. Cold episodes in the MV are associated with positive OLR anomalies, which extend over much of the central Andes, indicating reduced convective cloud cover during these extremes, but also affirm the large-scale nature of these events. At the same time, northeastern Brazil (NEB) registers negative OLR anomalies, strong convective activity and enhanced cloud cover because displacement of the South Atlantic Convergence Zone (SACZ) toward the northeast of its climatologic position. Further, it is associated with a weakening of the Bolivian High - Nordeste Low (BH-NL) system at upper levels, but also influenced by a low-level migratory high-pressure center develops at 30°S, 50°W; propagating from mid- to low latitudes as part of an extratropical Rossby wave train. In conclusion, cold episodes in the MV appear to be caused by radiative cooling associated with reduced cloudiness, rather than cold air advection. The reduced cloud cover in turn results from a robust large-scale pattern of westerly wind anomalies over central Peruvian Andes, inhibiting moisture influx, convective activity and hence cloud formation. At the same time NEB registers strong convective activity and enhanced cloud cover. This dipole is caused by a weakening of BH-NL system at upper levels, which is associated with a low-level migratory high-pressure center, propagating from mid- to low latitudes as part of an extratropical Rossby wave train.

The Role of Central Blood Pressure Monitoring in the Management of Hypertension.

PubMed

Ochoa, Adrian; Patarroyo-Aponte, Gabriel; Rahman, Mahboob

2018-04-19

Central blood pressure is a novel predictor of cardiovascular risk that can be measured in the clinical setting using currently available technology. This paper will review current available methods of central blood pressure monitoring as well as its impact in cardiac and renal disease. Both aortic and carotid systolic blood pressure are independently associated with cardiovascular mortality and serious cardiac events. Furthermore, studies show that systolic aortic blood pressure has been shown to be superior predictor of cardiovascular as compared to brachial blood pressure. Inhibitors of the renin angiotensin axis may have a beneficial effect on central blood pressure; however, long term studies evaluating the impact of lowering central blood pressure on clinical outcomes are lacking. Central blood pressure is a good predictor of cardiovascular risk. As more studies emerge demonstrating the value of central blood pressure as a therapeutic target, it is possible that targeting central blood pressure may become an important part of the armamentarium to lower cardiovascular risk.

Central and peripheral blood pressures in relation to plasma advanced glycation end products in a Chinese population.

PubMed

Huang, Q-F; Sheng, C-S; Kang, Y-Y; Zhang, L; Wang, S; Li, F-K; Cheng, Y-B; Guo, Q-H; Li, Y; Wang, J-G

2016-07-01

We investigated the association of plasma AGE (advanced glycation end product) concentration with central and peripheral blood pressures and central-to-brachial blood pressure amplification in a Chinese population. The study subjects were from a newly established residential area in the suburb of Shanghai. Using the SphygmoCor system, we recorded radial arterial waveforms and derived aortic waveforms by a generalized transfer function and central systolic and pulse pressure by calibration for brachial blood pressure measured with an oscillometric device. The central-to-brachial pressure amplification was expressed as the central-to-brachial systolic blood pressure difference and pulse pressure difference and ratio. Plasma AGE concentration was measured by the enzyme-linked immunosorbent assay method and logarithmically transformed for statistical analysis. The 1051 participants (age, 55.1±13.1 years) included 663 women. After adjustment for sex, age and other confounding factors, plasma AGE concentration was associated with central but not peripheral blood pressures and with some of the pressure amplification indexes. Indeed, each 10-fold increase in plasma AGE concentration was associated with 2.94 mm Hg (P=0.04) higher central systolic blood pressure and 2.39% lower central-to-brachial pulse pressure ratio (P=0.03). In further subgroup analyses, the association was more prominent in the presence of hypercholesterolemia (+8.11 mm Hg, P=0.008) for central systolic blood pressure and in the presence of overweight and obesity (-4.89%, P=0.009), diabetes and prediabetes (-6.26%, P=0.10) or current smoking (-6.68%, P=0.045) for central-to-brachial pulse pressure ratio. In conclusion, plasma AGE concentration is independently associated with central systolic blood pressure and pulse pressure amplification, especially in the presence of several modifiable cardiovascular risk factors.

Generalization of low pressure, gas-liquid, metastable sound speed to high pressures

NASA Technical Reports Server (NTRS)

Bursik, J. W.; Hall, R. M.

1981-01-01

A theory is developed for isentropic metastable sound propagation in high pressure gas-liquid mixtures. Without simplification, it also correctly predicts the minimum speed for low pressure air-water measurements where other authors are forced to postulate isothermal propagation. This is accomplished by a mixture heat capacity ratio which automatically adjusts from its single phase values to approximately the isothermal value of unity needed for the minimum speed. Computations are made for the pure components parahydrogen and nitrogen, with emphasis on the latter. With simplifying assumptions, the theory reduces to a well known approximate formula limited to low pressure.

42 CFR 84.86 - Component parts exposed to oxygen pressures; minimum requirements.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false Component parts exposed to oxygen pressures; minimum requirements. 84.86 Section 84.86 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY...

42 CFR 84.86 - Component parts exposed to oxygen pressures; minimum requirements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Component parts exposed to oxygen pressures; minimum requirements. 84.86 Section 84.86 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY...

42 CFR 84.86 - Component parts exposed to oxygen pressures; minimum requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Component parts exposed to oxygen pressures; minimum requirements. 84.86 Section 84.86 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY...

42 CFR 84.86 - Component parts exposed to oxygen pressures; minimum requirements.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false Component parts exposed to oxygen pressures; minimum requirements. 84.86 Section 84.86 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY...

42 CFR 84.86 - Component parts exposed to oxygen pressures; minimum requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Component parts exposed to oxygen pressures; minimum requirements. 84.86 Section 84.86 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY...

Interrelationships between intranarial pressure and biosonar clicks in the bottlenose dolphin (Tursiops truncatus)

NASA Astrophysics Data System (ADS)

Elsberry, Wesley R.; Cranford, Ted W.; Ridgway, Sam H.; Carder, Donald A.; Vanbonn, William G.; Blackwood, Diane J.; Carr, Jennifer A.; Evans, William E.

2002-05-01

Three Atlantic bottlenose dolphins (Tursiops truncatus) were given a target recognition biosonar task. During their performance of the task, both acoustic data in the far field and pressure within the bony nasal passages were digitally recorded (Elsberry et al., 1999). Analysis of over 15000 biosonar clicks provided new insights into odontocete biosonar sound production and is consistent with acoustic and pressure data taken from white whales (Delphinapterus leucas) during biosonar (Ridgway and Carder, 1988). Our work provides the first evidence for a minimum intranarial pressure during biosonar click production for any odontocete (11.8+/-0.5 kPascals over basal pressure). All three subjects exhibited nearly the same minimum tranarial pressure difference during biosonar click production. Clicks produced at or near this minimum intranarial pressure exhibited a wide range of acoustic power values. The acoustic power of a biosonar click was not highly correlated with intranarial pressure (R2=0.116). The radiated acoustic energy in biosonar clicks ranged from 1 to 1370 microJoules. Estimates of mechanical work during pressurization events were produced using a piston/cylinder model and intranarial volume data from prepared specimens and computed tomography scans. Mechanical work during pressurization events ranged from 2.74 to 23.0 Joules, with an average of 10.3 Joules.

Relation between inflammables and ignition sources in aircraft environments

NASA Technical Reports Server (NTRS)

Scull, Wilfred E

1951-01-01

A literature survey was conducted to determine the relation between aircraft ignition sources and inflammables. Available literature applicable to the problem of aircraft fire hazards is analyzed and discussed. Data pertaining to the effect of many variables on ignition temperatures, minimum ignition pressures, minimum spark-ignition energies of inflammables, quenching distances of electrode configurations, and size of openings through which flame will not propagate are presented and discussed. Ignition temperatures and limits of inflammability of gasoline in air in different test environments, and the minimum ignition pressures and minimum size of opening for flame propagation in gasoline-air mixtures are included; inerting of gasoline-air mixtures is discussed.

Impact of Parameterization of Physical Processes on Simulation of Track and Intensity of Tropical Cyclone Nargis (2008) with WRF-NMM Model

PubMed Central

Pattanayak, Sujata; Mohanty, U. C.; Osuri, Krishna K.

2012-01-01

The present study is carried out to investigate the performance of different cumulus convection, planetary boundary layer, land surface processes, and microphysics parameterization schemes in the simulation of a very severe cyclonic storm (VSCS) Nargis (2008), developed in the central Bay of Bengal on 27 April 2008. For this purpose, the nonhydrostatic mesoscale model (NMM) dynamic core of weather research and forecasting (WRF) system is used. Model-simulated track positions and intensity in terms of minimum central mean sea level pressure (MSLP), maximum surface wind (10 m), and precipitation are verified with observations as provided by the India Meteorological Department (IMD) and Tropical Rainfall Measurement Mission (TRMM). The estimated optimum combination is reinvestigated with six different initial conditions of the same case to have better conclusion on the performance of WRF-NMM. A few more diagnostic fields like vertical velocity, vorticity, and heat fluxes are also evaluated. The results indicate that cumulus convection play an important role in the movement of the cyclone, and PBL has a crucial role in the intensification of the storm. The combination of Simplified Arakawa Schubert (SAS) convection, Yonsei University (YSU) PBL, NMM land surface, and Ferrier microphysics parameterization schemes in WRF-NMM give better track and intensity forecast with minimum vector displacement error. PMID:22701366

Sedimentation across the central California oxygen minimum zone: an alternative coastal upwelling sequence.

USGS Publications Warehouse

Vercoutere, T.L.; Mullins, H.T.; McDougall, K.; Thompson, J.B.

1987-01-01

Distribution, abundance, and diversity of terrigenous, authigenous, and biogenous material provide evidence of the effect of bottom currents and oxygen minimum zone (OMZ) on continental slope sedimentation offshore central California. Three major OMZ facies are identified, along the upper and lower edges of OMZ and one at its core.-from Authors

Vocal warm-up increases phonation threshold pressure in soprano singers at high pitch.

PubMed

Motel, Tamara; Fisher, Kimberly V; Leydon, Ciara

2003-06-01

Vocal warm-up is thought to optimize singing performance. We compared effects of short-term, submaximal, vocal warm-up exercise with those of vocal rest on the soprano voice (n = 10, ages 19-21 years). Dependent variables were the minimum subglottic air pressure required for vocal fold oscillation to occur (phonation threshold pressure, Pth), and the maximum and minimum phonation fundamental frequency. Warm-up increased Pth for high pitch phonation (p = 0.033), but not for comfortable (p = 0.297) or low (p = 0.087) pitch phonation. No significant difference in the maximum phonation frequency (p = 0.193) or minimum frequency (p = 0.222) was observed. An elevated Pth at controlled high pitch, but an unchanging maximum and minimum frequency production suggests that short-term vocal exercise may increase the viscosity of the vocal fold and thus serve to stabilize the high voice.

Relationship Between 24-Hour Ambulatory Central Systolic Blood Pressure and Left Ventricular Mass: A Prospective Multicenter Study.

PubMed

Weber, Thomas; Wassertheurer, Siegfried; Schmidt-Trucksäss, Arno; Rodilla, Enrique; Ablasser, Cornelia; Jankowski, Piotr; Lorenza Muiesan, Maria; Giannattasio, Cristina; Mang, Claudia; Wilkinson, Ian; Kellermair, Jörg; Hametner, Bernhard; Pascual, Jose Maria; Zweiker, Robert; Czarnecka, Danuta; Paini, Anna; Salvetti, Massimo; Maloberti, Alessandro; McEniery, Carmel

2017-12-01

We investigated the relationship between left ventricular mass and brachial office as well as brachial and central ambulatory systolic blood pressure in 7 European centers. Central systolic pressure was measured with a validated oscillometric device, using a transfer function, and mean/diastolic pressure calibration. M-mode images were obtained by echocardiography, and left ventricular mass was determined by one single reader blinded to blood pressure. We studied 289 participants (137 women) free from antihypertensive drugs (mean age: 50.8 years). Mean office blood pressure was 145/88 mm Hg and mean brachial and central ambulatory systolic pressures were 127 and 128 mm Hg, respectively. Mean left ventricular mass was 93.3 kg/m 2 , and 25.6% had left ventricular hypertrophy. The correlation coefficient between left ventricular mass and brachial office, brachial ambulatory, and central ambulatory systolic pressure was 0.29, 0.41, and 0.47, respectively ( P =0.003 for comparison between brachial office and central ambulatory systolic pressure and 0.32 for comparison between brachial and central ambulatory systolic pressure). The results were consistent for men and women, and young and old participants. The areas under the curve for prediction of left ventricular hypertrophy were 0.618, 0.635, and 0.666 for brachial office, brachial, and central ambulatory systolic pressure, respectively ( P =0.03 for comparison between brachial and central ambulatory systolic pressure). In younger participants, central ambulatory systolic pressure was superior to both other measurements. Central ambulatory systolic pressure, measured with an oscillometric cuff, shows a strong trend toward a closer association with left ventricular mass and hypertrophy than brachial office/ambulatory systolic pressure. URL: https://www.clinicaltrials.gov. Unique identifier: NCT01278732. © 2017 American Heart Association, Inc.

Heterogeneous mineral assemblages in martian meteorite Tissint as a result of a recent small impact event on Mars

NASA Astrophysics Data System (ADS)

Walton, E. L.; Sharp, T. G.; Hu, J.; Filiberto, J.

2014-09-01

The microtexture and mineralogy of shock melts in the Tissint martian meteorite were investigated using scanning electron microscopy, Raman spectroscopy, transmission electron microscopy and synchrotron micro X-ray diffraction to understand shock conditions and duration. Distinct mineral assemblages occur within and adjacent to the shock melts as a function of the thickness and hence cooling history. The matrix of thin veins and pockets of shock melt consists of clinopyroxene + ringwoodite ± stishovite embedded in glass with minor Fe-sulfide. The margins of host rock olivine in contact with the melt, as well as entrained olivine fragments, are now amorphosed silicate perovskite + magnesiowüstite or clinopyroxene + magnesiowüstite. The pressure stabilities of these mineral assemblages are ∼15 GPa and >19 GPa, respectively. The ∼200-μm-wide margin of a thicker, mm-size (up to 1.4 mm) shock melt vein contains clinopyroxene + olivine, with central regions comprising glass + vesicles + Fe-sulfide spheres. Fragments of host rock within the melt are polycrystalline olivine (after olivine) and tissintite + glass (after plagioclase). From these mineral assemblages the crystallization pressure at the vein edge was as high as 14 GPa. The interior crystallized at ambient pressure. The shock melts in Tissint quench-crystallized during and after release from the peak shock pressure; crystallization pressures and those determined from olivine dissociation therefore represent the minimum shock loading. Shock deformation in host rock minerals and complete transformation of plagioclase to maskelynite suggest the peak shock pressure experienced by Tissint ⩾ 29-30 GPa. These pressure estimates support our assessment that the peak shock pressure in Tissint was significantly higher than the minimum 19 GPa required to transform olivine to silicate perovskite plus magnesiowüstite. Small volumes of shock melt (<100 μm) quench rapidly (0.01 s), whereas thermal equilibration will occur within 1.2 s in larger volumes of melt (1 mm2). The apparent variation in shock pressure recorded by variable mineral assemblages within and around shock melts in Tissint is consistent with a shock pulse on the order of 10-20 ms combined with a longer duration of post-shock cooling and complex thermal history. This implies that the impact on Mars that shocked and ejected Tissint at ∼1 Ma was not exceptionally large.

49 CFR 178.58 - Specification 4DA welded steel cylinders for aircraft use.

Code of Federal Regulations, 2010 CFR

2010-10-01

... stress in pounds psi; P = test pressure prescribed for water jacket test, i.e., at least 2 times service... seamless hemispheres) or a circumferentially welded cylinder (two seamless drawn shells) with a water... the wall stress at the minimum specified test pressure may not exceed 67 percent of the minimum...

49 CFR 195.306 - Test medium.

Code of Federal Regulations, 2010 CFR

2010-10-01

... which produces a hoop stress of 50 percent of specified minimum yield strength; (3) The test section is... pressure is equal to or greater than a pressure that produces a hoop stress of 50 percent of specified minimum yield strength; (3) The maximum hoop stress during the test does not exceed 80 percent of...

49 CFR 195.306 - Test medium.

Code of Federal Regulations, 2012 CFR

2012-10-01

... which produces a hoop stress of 50 percent of specified minimum yield strength; (3) The test section is... pressure is equal to or greater than a pressure that produces a hoop stress of 50 percent of specified minimum yield strength; (3) The maximum hoop stress during the test does not exceed 80 percent of...

49 CFR 179.300-6 - Thickness of plates.

Code of Federal Regulations, 2010 CFR

2010-10-01

....037 Where: d = inside diameter in inches; E = 1.0 welded joint efficiency; P = minimum required bursting pressure in psig; S = minimum tensile strength of plate material in p.s.i. as prescribed in § 179... −d 2) where: d = inside diameter in inches; D = outside diameter in inches; p = tank test pressure in...

Convex central configurations for the n-body problem

NASA Astrophysics Data System (ADS)

Xia, Zhihong

We give a simple proof of a classical result of MacMillan and Bartky (Trans. Amer. Math. Soc. 34 (1932) 838) which states that, for any four positive masses and any assigned order, there is a convex planar central configuration. Moreover, we show that the central configurations we find correspond to local minima of the potential function with fixed moment of inertia. This allows us to show that there are at least six local minimum central configurations for the planar four-body problem. We also show that for any assigned order of five masses, there is at least one convex spatial central configuration of local minimum type. Our method also applies to some other cases.

Evidence for a central mode of action for etoricoxib (COX-2 inhibitor) in patients with painful knee osteoarthritis.

PubMed

Arendt-Nielsen, Lars; Egsgaard, Line Lindhardt; Petersen, Kristian Kjær

2016-08-01

The COX-2 inhibitor etoricoxib modulates the peripheral and central nociceptive mechanisms in animals. This interaction has not been studied in patients with pain. This randomized, double-blind, placebo-controlled, 2-way crossover, 4-week treatment study investigated the pain mechanisms modulated by etoricoxib in patients with painful knee osteoarthritis. Patients were randomized to group A (60 mg/d etoricoxib followed by placebo) or B (placebo followed by 60 mg/d etoricoxib). The quantitative, mechanistic pain biomarkers were pressure pain thresholds, temporal summation (TS), and conditioning pain modulation. Clinical readouts were Brief Pain Inventory, WOMAC, painDETECT questionnaire (PD-Q), and time and pain intensity during walking and stair climbing. Etoricoxib as compared with placebo significantly modulated the pressure pain thresholds (P = 0.012, localized sensitization) at the knee and leg (control site) (P = 0.025, spreading sensitization) and TS assessed from the knee (P = 0.038) and leg (P = 0.045). Conditioning pain modulation was not modulated. The Brief Pain Inventory (pain scores), PD-Q, WOMAC, and walking and stair climbing tests were all significantly improved by etoricoxib. Based on a minimum of 30% or 50% pain alleviation (day 0-day 28), responders and nonresponders were defined. The nonresponders showed a significant association between increased facilitation of TS and increased pain alleviation. None of the other parameters predicted the degree of pain alleviation. Generally, a responder to etoricoxib has the most facilitated TS. In conclusion, etoricoxib (1) modulated central pain modulatory mechanisms and (2) improved pain and function in painful osteoarthritis. Stronger facilitation of TS may indicate a better response to etoricoxib, supporting the central mode-of-action of the drug.

Use of linkage mapping and centrality analysis across habitat gradients to conserve connectivity of gray wolf populations in western North America.

PubMed

Carroll, Carlos; McRae, Brad H; Brookes, Allen

2012-02-01

Centrality metrics evaluate paths between all possible pairwise combinations of sites on a landscape to rank the contribution of each site to facilitating ecological flows across the network of sites. Computational advances now allow application of centrality metrics to landscapes represented as continuous gradients of habitat quality. This avoids the binary classification of landscapes into patch and matrix required by patch-based graph analyses of connectivity. It also avoids the focus on delineating paths between individual pairs of core areas characteristic of most corridor- or linkage-mapping methods of connectivity analysis. Conservation of regional habitat connectivity has the potential to facilitate recovery of the gray wolf (Canis lupus), a species currently recolonizing portions of its historic range in the western United States. We applied 3 contrasting linkage-mapping methods (shortest path, current flow, and minimum-cost-maximum-flow) to spatial data representing wolf habitat to analyze connectivity between wolf populations in central Idaho and Yellowstone National Park (Wyoming). We then applied 3 analogous betweenness centrality metrics to analyze connectivity of wolf habitat throughout the northwestern United States and southwestern Canada to determine where it might be possible to facilitate range expansion and interpopulation dispersal. We developed software to facilitate application of centrality metrics. Shortest-path betweenness centrality identified a minimal network of linkages analogous to those identified by least-cost-path corridor mapping. Current flow and minimum-cost-maximum-flow betweenness centrality identified diffuse networks that included alternative linkages, which will allow greater flexibility in planning. Minimum-cost-maximum-flow betweenness centrality, by integrating both land cost and habitat capacity, allows connectivity to be considered within planning processes that seek to maximize species protection at minimum cost. Centrality analysis is relevant to conservation and landscape genetics at a range of spatial extents, but it may be most broadly applicable within single- and multispecies planning efforts to conserve regional habitat connectivity. ©2011 Society for Conservation Biology.

All APAPs Are Not Equivalent for the Treatment of Sleep Disordered Breathing: A Bench Evaluation of Eleven Commercially Available Devices

PubMed Central

Zhu, Kaixian; Roisman, Gabriel; Aouf, Sami; Escourrou, Pierre

2015-01-01

Study Objectives: This study challenged on a bench-test the efficacy of auto-titrating positive airway pressure (APAP) devices for obstructive sleep disordered breathing treatment and evaluated the accuracy of the device reports. Methods: Our bench consisted of an active lung simulator and a Starling resistor. Eleven commercially available APAP devices were evaluated on their reactions to single-type SDB sequences (obstructive apnea and hypopnea, central apnea, and snoring), and to a long general breathing scenario (5.75 h) simulating various SDB during four sleep cycles and to a short scenario (95 min) simulating one sleep cycle. Results: In the single-type sequence of 30-minute repetitive obstructive apneas, only 5 devices normalized the airflow (> 70% of baseline breathing amplitude). Similarly, normalized breathing was recorded with 8 devices only for a 20-min obstructive hypopnea sequence. Five devices increased the pressure in response to snoring. Only 4 devices maintained a constant minimum pressure when subjected to repeated central apneas with an open upper airway. In the long general breathing scenario, the pressure responses and the treatment efficacy differed among devices: only 5 devices obtained a residual obstructive AHI < 5/h. During the short general breathing scenario, only 2 devices reached the same treatment efficacy (p < 0.001), and 3 devices underestimated the AHI by > 10% (p < 0.001). The long scenario led to more consistent device reports. Conclusion: Large differences between APAP devices in the treatment efficacy and the accuracy of report were evidenced in the current study. Citation: Zhu K, Roisman G, Aouf S, Escourrou P. All APAPs are not equivalent for the treatment of sleep disordered breathing: a bench evaluation of eleven commercially available devices. J Clin Sleep Med 2015;11(7):725–734. PMID:25766708

49 CFR 178.58 - Specification 4DA welded steel cylinders for aircraft use.

Code of Federal Regulations, 2011 CFR

2011-10-01

... stress in pounds psi; P = test pressure prescribed for water jacket test, i.e., at least 2 times service... hemispheres) or a circumferentially welded cylinder (two seamless drawn shells) with a water capacity not over... the wall stress at the minimum specified test pressure may not exceed 67 percent of the minimum...

Relation Between Inflammables and Ignition Sources in Aircraft Environments

NASA Technical Reports Server (NTRS)

Scull, Wilfred E

1950-01-01

A literature survey was conducted to determine the relation between aircraft ignition sources and inflammables. Available literature applicable to the problem of aircraft fire hazards is analyzed and, discussed herein. Data pertaining to the effect of many variables on ignition temperatures, minimum ignition pressures, and minimum spark-ignition energies of inflammables, quenching distances of electrode configurations, and size of openings incapable of flame propagation are presented and discussed. The ignition temperatures and the limits of inflammability of gasoline in air in different test environments, and the minimum ignition pressure and the minimum size of openings for flame propagation of gasoline - air mixtures are included. Inerting of gasoline - air mixtures is discussed.

Multi-bottle, no compressor, mean pressure control system for a Stirling engine

DOEpatents

Corey, John A.

1990-01-01

The invention relates to an apparatus for mean pressure control of a Stirling engine without the need for a compressor. The invention includes a multi-tank system in which there is at least one high pressure level tank and one low pressure level tank wherein gas flows through a maximum pressure and supply line from the engine to the high pressure tank when a first valve is opened until the maximum pressure of the engine drops below that of the high pressure tank opening an inlet regulator to permit gas flow from the engine to the low pressure tank. When gas flows toward the engine it flows through the minimum pressure supply line 2 when a second valve is opened from the low pressure tank until the tank reaches the engine's minimum pressure level at which time the outlet regulator opens permitting gas to be supplied from the high pressure tank to the engine. Check valves between the two tanks prevent any backflow of gas from occurring.

Cost of and soil loss on "minimum-standard" forest truck roads constructed in the central Appalachians

Treesearch

J. N. Kochenderfer; G. W. Wendel; H. Clay Smith

1984-01-01

A "minimum-standard" forest truck road that provides efficient and environmentally acceptable access for several forest activities is described. Cost data are presented for eight of these roads constructed in the central Appalachians. The average cost per mile excluding gravel was $8,119. The range was $5,048 to $14,424. Soil loss was measured from several...

Effects of bisoprolol and cilazapril on the central retinal artery blood flow in patients with essential hypertension—preliminary results

PubMed Central

2010-01-01

Background A growing body of evidence suggests that effective blood pressure reduction may inhibit the progression of microvascular damage in patients with essential arterial hypertension. However, the potential influence of anti-hypertensive drugs on ocular circulation has not been studied sufficiently. Purpose The aim of our study was to evaluate the effects of anti-hypertensive therapy on blood flow in the central retinal artery in patients with systemic arterial hypertension. Material and methods Twenty patients with essential arterial hypertension, aged 32–46 years, were examined with Doppler ultrasonography (10 MHz ultrasound probe). Blood flow velocities, pulsatility, and vascular resistance were determined before and 3 hours after systemic application of either bisoprolol 5 mg or cilazapril 2.5 mg. Results Administered bisoprolol significantly decreased maximum (9.8 ± 0.5 cm/s versus 8.5 ± 0.6 cm/s; P < 0.05) and minimum (2.75 ± 0.19 cm/s versus 1.75 ± 0.27 cm/s; P < 0.02) velocity, increased the Pourcellot's index (0.71 to 0.79; P < 0.05) in central retinal artery. There were no statistically significant changes in central retinal artery blood flow after administration of cilazapril. Conclusion Systemic application of beta-blockers may unfavourably disturb the ocular blood flow. PMID:20858158

Relationship of central and peripheral blood pressure to left ventricular mass in hypertensive patients.

PubMed

Pérez-Lahiguera, Francisco J; Rodilla, Enrique; Costa, Jose A; Gonzalez, Carmen; Martín, Joaquin; Pascual, Jose M

2012-12-01

The purpose of the present study was to assess the relationship of central and peripheral blood pressure to left ventricular mass. Cross-sectional study that included 392 never treated hypertensive individuals. Measurement of office, 24-h ambulatory, and central blood pressure (obtained using applanation tonometry) and determination of left ventricular mass by echocardiography were performed in all patients. In a multiple regression analysis, with adjustment for age, gender and metabolic syndrome, 24-h blood pressure was more closely related to ventricular mass than the respective office and central blood pressures. Systolic blood pressures always exhibited a higher correlation than diastolic blood pressures in all 3 determinations. The correlation between left ventricular mass index and 24-h systolic blood pressure was higher than that of office (P<.002) or central systolic blood pressures (P<.002). Changes in 24-h systolic blood pressure caused the greatest variations in left ventricular mass index (P<.001). In our population of untreated middle-aged hypertensive patients, left ventricular mass index is more closely related to 24-h ambulatory blood pressure than to office or central blood pressure. Central blood pressure does not enable us to better identify patients with left ventricular hypertrophy. Copyright © 2012 Sociedad Española de Cardiología. Published by Elsevier Espana. All rights reserved.

30 CFR 18.98 - Enclosures, joints, and fastenings; pressure testing.

Code of Federal Regulations, 2013 CFR

2013-07-01

... consistent with unyielding components during a pressure-time history as derived from a series of oscillograms...; pressure testing. (a) Cast or welded enclosures shall be designed to withstand a minimum internal pressure...

30 CFR 18.98 - Enclosures, joints, and fastenings; pressure testing.

Code of Federal Regulations, 2012 CFR

2012-07-01

... consistent with unyielding components during a pressure-time history as derived from a series of oscillograms...; pressure testing. (a) Cast or welded enclosures shall be designed to withstand a minimum internal pressure...

30 CFR 18.98 - Enclosures, joints, and fastenings; pressure testing.

Code of Federal Regulations, 2014 CFR

2014-07-01

... consistent with unyielding components during a pressure-time history as derived from a series of oscillograms...; pressure testing. (a) Cast or welded enclosures shall be designed to withstand a minimum internal pressure...

30 CFR 18.98 - Enclosures, joints, and fastenings; pressure testing.

Code of Federal Regulations, 2010 CFR

2010-07-01

... consistent with unyielding components during a pressure-time history as derived from a series of oscillograms...; pressure testing. (a) Cast or welded enclosures shall be designed to withstand a minimum internal pressure...

30 CFR 18.98 - Enclosures, joints, and fastenings; pressure testing.

Code of Federal Regulations, 2011 CFR

2011-07-01

... consistent with unyielding components during a pressure-time history as derived from a series of oscillograms...; pressure testing. (a) Cast or welded enclosures shall be designed to withstand a minimum internal pressure...

49 CFR 178.50 - Specification 4B welded or brazed steel cylinders.

Code of Federal Regulations, 2011 CFR

2011-10-01

...)] / (D2 − d2) Where: S = wall stress in psi; P = minimum test pressure prescribed for water jacket test or... seams that are forged lap-welded or brazed and with water capacity (nominal) not over 1,000 pounds and a... calculated wall stress at minimum test pressure (paragraph (i)(4) of this section) may not exceed the...

49 CFR 178.50 - Specification 4B welded or brazed steel cylinders.

Code of Federal Regulations, 2010 CFR

2010-10-01

...)] / (D2 − d2) Where: S = wall stress in psi; P = minimum test pressure prescribed for water jacket test or... longitudinal seams that are forged lap-welded or brazed and with water capacity (nominal) not over 1,000 pounds... calculated wall stress at minimum test pressure (paragraph (i)(4) of this section) may not exceed the...

Response of stream benthic macroinvertebrates to current water management in Alpine catchments massively developed for hydropower.

PubMed

Quadroni, Silvia; Crosa, Giuseppe; Gentili, Gaetano; Espa, Paolo

2017-12-31

The present work focuses on evaluating the ecological effects of hydropower-induced streamflow alteration within four catchments in the central Italian Alps. Downstream from the water diversions, minimum flows are released as an environmental protection measure, ranging approximately from 5 to 10% of the mean annual natural flow estimated at the intake section. Benthic macroinvertebrates as well as daily averaged streamflow were monitored for five years at twenty regulated stream reaches, and possible relationships between benthos-based stream quality metrics and environmental variables were investigated. Despite the non-negligible inter-site differences in basic streamflow metrics, benthic macroinvertebrate communities were generally dominated by few highly resilient taxa. The highest level of diversity was detected at sites where upstream minimum flow exceedance is higher and further anthropogenic pressures (other than hydropower) are lower. However, according to the current Italian normative index, the ecological quality was good/high on average at all of the investigated reaches, thus complying the Water Framework Directive standards. Copyright © 2017 Elsevier B.V. All rights reserved.

Methods and apparatus for moving and separating materials exhibiting different physical properties

DOEpatents

Peterson, Stephen C.; Brimhall, Owen D.; McLaughlin, Thomas J.; Baker, Charles D.; Sparks, Sam L.

1991-01-01

Methods and apparatus for controlling the movement of materials having different physical properties when one of the materials is a fluid. The invention does not rely on flocculation, sedimentation, centrifugation, the buoyancy of the materials, or any other gravity dependent characteristic, in order to achieve its desired results. The methods of the present invention provide that a first acoustic wave is propagated through a vessel containing the materials. A second acoustic wave, at a frequency different than the first acoustic wave, is also propagated through the vessel so that the two acoustic waves are superimposed upon each other. The superimposition of the two waves creates a beat frequency wave. The beat frequency wave comprises pressure gradients dividing regions of maximum and minimum pressure. The pressure gradients and the regions of maximum and minimum pressure move through space and time at a group velocity. The moving pressure gradients and regions of maximum and minimum pressure act upon the materials so as to move one of the materials towards a predetermined location in the vessel. The present invention provides that the materials may be controllably moved toward a location, aggregated at a particular location, or physically separated from each other.

Methods and apparatus for moving and separating materials exhibiting different physical properties

DOEpatents

Peterson, Stephen C.; Brimhall, Owen D.; McLaughlin, Thomas J.; Baker, Charles D.; Sparks, Sam L.

1988-01-01

Methods and apparatus for controlling the movement of materials having different physical properties when one of the materials is a fluid. The invention does not rely on flocculation, sedimentation, centrifugation, the buoyancy of the materials, or any other gravity dependent characteristic, in order to achieve its desired results. The methods of the present invention provide that a first acoustic wave is progpagated through a vessel containing the materials. A second acoustic wave, at a frequency different than the first acoustic wave, is also propagated through the vessel so that the two acoustic waves are superimposed upon each other. The superimposition of the two waves creates a beat frequency wave. The beat frequency wave comprises pressure gradients dividing regions of maximum and minimum pressure. The pressure gradients and the regions of maximum and minimum pressure move through space and time at a group velocity. The moving pressure gradients and regions of maximum and minimum pressure act upon the marterials so as to move one of the materials towards a predetermined location in the vessel. The present invention provides that the materials may be controllably moved toward a location, aggreated at a particular location, or physically separated from each other.

30 CFR 250.616 - Blowout prevention equipment.

Code of Federal Regulations, 2014 CFR

2014-07-01

... pressure rating of the BOP system and system components shall exceed the expected surface pressure to which they may be subjected. If the expected surface pressure exceeds the rated working pressure of the... pressure limitations that will be applied during each mode of pressure control. (b) The minimum BOP system...

30 CFR 250.616 - Blowout prevention equipment.

Code of Federal Regulations, 2013 CFR

2013-07-01

... pressure rating of the BOP system and system components shall exceed the expected surface pressure to which they may be subjected. If the expected surface pressure exceeds the rated working pressure of the... pressure limitations that will be applied during each mode of pressure control. (b) The minimum BOP system...

30 CFR 250.615 - Blowout prevention equipment.

Code of Federal Regulations, 2012 CFR

2012-07-01

... pressure rating of the BOP system and system components shall exceed the expected surface pressure to which they may be subjected. If the expected surface pressure exceeds the rated working pressure of the... pressure limitations that will be applied during each mode of pressure control. (b) The minimum BOP system...

Investigation of alternative layouts for the supercritical carbon dioxide Brayton cycle for a sodium-cooled fast reactor.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moisseytsev, A.; Sienicki, J. J.

2009-07-01

Analyses of supercritical carbon dioxide (S-CO{sub 2}) Brayton cycle performance have largely settled on the recompression supercritical cycle (or Feher cycle) incorporating a flow split between the main compressor downstream of heat rejection, a recompressing compressor providing direct compression without heat rejection, and high and low temperature recuperators to raise the effectiveness of recuperation and the cycle efficiency. Alternative cycle layouts have been previously examined by Angelino (Politecnico, Milan), by MIT (Dostal, Hejzlar, and Driscoll), and possibly others but not for sodium-cooled fast reactors (SFRs) operating at relatively low core outlet temperature. Thus, the present authors could not be suremore » that the recompression cycle is an optimal arrangement for application to the SFR. To ensure that an advantageous alternative layout has not been overlooked, several alternative cycle layouts have been investigated for a S-CO{sub 2} Brayton cycle coupled to the Advanced Burner Test Reactor (ABTR) SFR preconceptual design having a 510 C core outlet temperature and a 470 C turbine inlet temperature to determine if they provide any benefit in cycle performance (e.g., enhanced cycle efficiency). No such benefits were identified, consistent with the previous examinations, such that attention was devoted to optimizing the recompression supercritical cycle. The effects of optimizing the cycle minimum temperature and pressure are investigated including minimum temperatures and/or pressures below the critical values. It is found that improvements in the cycle efficiency of 1% or greater relative to previous analyses which arbitrarily fixed the minimum temperature and pressure can be realized through an optimal choice of the combination of the minimum cycle temperature and pressure (e.g., for a fixed minimum temperature there is an optimal minimum pressure). However, this leads to a requirement for a larger cooler for heat rejection which may impact the tradeoff between efficiency and capital cost. In addition, for minimum temperatures below the critical temperature, a lower heat sink temperature is required the availability of which is dependent upon the climate at the specific plant site.« less

Combined high-power ultrasound and high-pressure homogenization nanoemulsification: The effect of energy density, oil content and emulsifier type and content.

PubMed

Calligaris, Sonia; Plazzotta, Stella; Valoppi, Fabio; Anese, Monica

2018-05-01

Combinations of ultrasound (US) and high-pressure homogenization (HPH) at low-medium energy densities were studied as alternative processes to individual US and HPH to produce Tween 80 and whey protein stabilized nanoemulsions, while reducing the energy input. To this aim, preliminary trials were performed to compare emulsification efficacy of single and combined HPH and US treatments delivering low-medium energy densities. Results highlighted the efficacy of US-HPH combined process in reducing the energy required to produce nanoemulsions stabilized with both Tween 80 and whey protein isolate. Subsequently, the effect of emulsifier content (1-3% w/w), oil amount (10-20% w/w) and energy density (47-175 MJ/m 3 ) on emulsion mean particle diameter was evaluated by means of a central composite design. Particles of 140-190 nm were obtained by delivering 175 MJ/m 3 energy density at emulsions containing 3% (w/w) Tween 80 and 10% (w/w) oil. In the case of whey protein isolate stabilized emulsions, a reduced emulsifier amount (1% w/w) and intermediate energy density (120 MJ/m 3 ) allowed a minimum droplet size around 220-250 nm to be achieved. Results showed that, in both cases, at least 50% of the energy density should be delivered by HPH to obtain the minimum particle diameter. Copyright © 2018 Elsevier Ltd. All rights reserved.

Impacts of sodium-glucose co-transporter type 2 inhibitors on central blood pressure.

PubMed

Takenaka, Tsuneo; Ohno, Yoichi; Suzuki, Hiromichi

2018-03-01

To assess the effects of sodium-glucose co-transporter type 2 inhibitors on central blood pressure, an important determinant of cardiovascular events. Canagliflozin, Empagliflozin or Luseogliflozin was given for 102 type 2 diabetic patients with hypertension and nephropathy. Central blood pressure was evaluated by radial tonometry. Clinical parameters were followed for 6 months. Three differing sodium-glucose co-transporter type 2 inhibitors similarly reduced brachial and central blood pressures, casual blood sugar, haemoglobin A1c, estimated glomerular filtration rate and albuminuria without significant changes in pulse rate and lipid profiles. Central systolic blood pressure was associated with the decreases in albuminuria by sodium-glucose co-transporter type 2 inhibitors. Comparable influences of various sodium-glucose co-transporter type 2 inhibitors on central blood pressure suggest class effects.

Intraocular pressure reduction and regulation system

NASA Technical Reports Server (NTRS)

Baehr, E. F.; Burnett, J. E.; Felder, S. F.; Mcgannon, W. J.

1979-01-01

An intraocular pressure reduction and regulation system is described and data are presented covering performance in: (1) reducing intraocular pressure to a preselected value, (2) maintaining a set minimum intraocular pressure, and (3) reducing the dynamic increases in intraocular pressure resulting from external loads applied to the eye.

FAST TRACK COMMUNICATION: Metal vapour causes a central minimum in arc temperature in gas-metal arc welding through increased radiative emission

NASA Astrophysics Data System (ADS)

Schnick, M.; Füssel, U.; Hertel, M.; Spille-Kohoff, A.; Murphy, A. B.

2010-01-01

A computational model of the argon arc plasma in gas-metal arc welding (GMAW) that includes the influence of metal vapour from the electrode is presented. The occurrence of a central minimum in the radial distributions of temperature and current density is demonstrated. This is in agreement with some recent measurements of arc temperatures in GMAW, but contradicts other measurements and also the predictions of previous models, which do not take metal vapour into account. It is shown that the central minimum is a consequence of the strong radiative emission from the metal vapour. Other effects of the metal vapour, such as the flux of relatively cold vapour from the electrode and the increased electrical conductivity, are found to be less significant. The different effects of metal vapour in gas-tungsten arc welding and GMAW are explained.

Influence of nitromethane concentration on ignition energy and explosion parameters in gaseous nitromethane/air mixtures.

PubMed

Zhang, Qi; Li, Wei; Lin, Da-Chao; He, Ning; Duan, Yun

2011-01-30

The aim of this paper is to provide new experimental data of the minimum ignition energy (MIE) of gaseous nitromethane/air mixtures to discuss the explosion pressure and the flame temperature as a function of nitromethane concentration. Observations on the influence of nitromethane concentration on combustion pressure and temperature through the pressure and temperature measure system show that peak temperature (the peak of combustion temperature wave) is always behind peak pressure (the peak of the combustion pressure wave) in arrival time, the peak combustion pressure of nitromethane increases in the range of its volume fraction 10-40% as the concentration of nitromethane increases, and it slightly decreases in the range of 40-50%. The maximum peak pressure is equal to 0.94 MPa and the minimum peak pressure 0.58 MPa. Somewhat similar to the peak pressure, the peak combustion temperature increases with the volume fraction of nitromethane in the range of 10-40%, and slightly decreases in 40-50%. The maximum peak temperature is 1340 °C and the minimum 860 °C. The combustion temperature rise rate increases with the concentration of nitromethane in 10-30%, while decreases in 30-50% and its maximum value of combustion temperature rise rate in 10-50% is 4200 °C/s at the volume fraction of 30%. Influence of the concentration of nitromethane on the combustion pressure rise rate is relatively complicated, and the maximum value of rise rate of combustion pressure wave in 10-50% is 11 MPa/s at the concentration 20%. Copyright © 2010 Elsevier B.V. All rights reserved.

"Deflategate": Time, Temperature, and Moisture Effects on Football Pressure

NASA Astrophysics Data System (ADS)

Blumenthal, Jack; Beljak, Lauren; Macatangay, Dahlia-Marie; Helmuth-Malone, Lilly; McWilliams, Catharina; Raptis, Sofia

2016-09-01

In a recent paper in TPT, DiLisi and Rarick used the National Football League "Deflategate" controversy to introduce to physics students the physics of a bouncing ball. In this paper, we measure and analyze the environmental effects of time, ambient temperature, and moisture on the internal pressure of an NFL football. We focus on the rate of pressure recovery that occurs when a cold football (either wet or dry) is returned to the warm locker room environment where the pressure was initially measured. Both studies stem from the so-called NFL "Deflategate" controversy in which footballs that initially met a minimum internal pressure requirement were rechecked at halftime of the AFC Championship game, and in some cases were reported to have fallen below the minimum pressure requirement. The question is whether the pressure changes were due to environmental exposure or rather to some air being released from the balls, or both.

Comparison of right atrial pressure and central venous pressures measured at various anatomical locations in children.

PubMed

Lin, Ming-Chih; Fu, Yun-Ching; Jan, Sheng-Ling; Chen, Ying-Tsung; Chi, Ching-Shiang

2005-01-01

To compare the right atrial pressure to the central venous pressures measured at different points in spontaneously breathing children and try to find a formula to estimate right atrial pressure by central venous pressure measurement. Fifty-one children, aged 5 +/- 4.7 years, who underwent right heart catheterization were studied. All patients were sedated and breathed naturally. The mean pressure was the electronic mean of nine heart beats calculated by Philips BC4000 digital angiographic system. Mean pressure of the right atrium was compared to those measured at the high superior vena cava (SVC), low SVC, high inferior vena cava (IVC) (T10-11), middle IVC (L1-2), low IVC (L3-4), and iliac vein (L5-S1). Mean pressures of central veins were significantly higher than that of the right atrium (all p<0.01). Adjusted central venous pressures of SVC-0.5, high IVC-1.5, middle IVC-2, low IVC-2.5, and iliac vein-3 (mmHg) had a good agreement with the right atrial pressure. Central venous pressures are significantly higher than the right atrial pressure in spontaneously breathing children. Adjusted pressures of SVC-0.5, high IVC-1.5, middle IVC-2, low IVC-2.5, and iliac vein-3 (mmHg) can accurately reflect the right atrial pressure.

40 CFR Table 3 to Subpart Ec of... - Operating Parameters To Be Monitored and Minimum Measurement and Recording Frequencies

Code of Federal Regulations, 2011 CFR

2011-07-01

... scrubber followed by fabric filter Wet scrubber Dry scrubber followed by fabric filter and wet scrubber... flow rate Hourly 1×hour ✔ ✔ Minimum pressure drop across the wet scrubber or minimum horsepower or amperage to wet scrubber Continuous 1×minute ✔ ✔ Minimum scrubber liquor flow rate Continuous 1×minute...

Variability in alignment of central venous pressure transducer to physiologic reference point in the intensive care unit-A descriptive and correlational study.

PubMed

Sjödin, Carl; Sondergaard, Soren; Johansson, Lotta

2018-06-01

The phlebostatic axis is the most commonly used anatomical external reference point for central venous pressure measurements. Deviation in the central venous pressure transducer alignment from the phlebostatic axis causes inadequate pressure readings, which may affect treatment decisions for critically ill patients in intensive care units. The primary aim of the study was to assess the variability in central venous pressure transducer levelling in the intensive care unit. We also assessed whether patient characteristics impacted on central venous pressure transducer alignment deviation. A sample of 61 critical care nurses was recruited and asked to place a transducer at the appropriate level for central venous pressure measurement. The measurements were performed in the intensive care unit on critically ill patients in supine and Fowler's positions. The variability among the participants using eyeball levelling and a laser levelling device was calculated in both sessions and adjusted for patient characteristics. A significant variation was found among critical care nurses in the horizontal levelling of the pressure transducer placement when measuring central venous pressure in the intensive care unit. Using a laser levelling device did not reduce the deviation from the phlebostatic axis. Patient characteristics had little impact on the deviation in the measurements. The anatomical external landmark for the phlebostatic axis varied between critical care nurses, as the variation in the central venous pressure transducer placement was not reduced with a laser levelling device. Standardisation of a zero-level for vascular pressures should be considered to reduce the variability in vascular pressure readings in the intensive care unit to improve patient treatment decisions. Further studies are needed to evaluate critical care nurses' knowledge and use of central venous pressure monitoring and whether assistive tools and/or routines can improve the accuracy in vascular pressure measurements in intensive care units. Copyright © 2018 Australian College of Critical Care Nurses Ltd. Published by Elsevier Ltd. All rights reserved.

Effects of tidal current phase at the junction of two straits

USGS Publications Warehouse

Warner, J.; Schoellhamer, D.; Burau, J.; Schladow, G.

2002-01-01

Estuaries typically have a monotonic increase in salinity from freshwater at the head of the estuary to ocean water at the mouth, creating a consistent direction for the longitudinal baroclinic pressure gradient. However, Mare Island Strait in San Francisco Bay has a local salinity minimum created by the phasing of the currents at the junction of Mare Island and Carquinez Straits. The salinity minimum creates converging baroclinic pressure gradients in Mare Island Strait. Equipment was deployed at four stations in the straits for 6 months from September 1997 to March 1998 to measure tidal variability of velocity, conductivity, temperature, depth, and suspended sediment concentration. Analysis of the measured time series shows that on a tidal time scale in Mare Island Strait, the landward and seaward baroclinic pressure gradients in the local salinity minimum interact with the barotropic gradient, creating regions of enhanced shear in the water column during the flood and reduced shear during the ebb. On a tidally averaged time scale, baroclinic pressure gradients converge on the tidally averaged salinity minimum and drive a converging near-bed and diverging surface current circulation pattern, forming a "baroclinic convergence zone" in Mare Island Strait. Historically large sedimentation rates in this area are attributed to the convergence zone. 

A Transmission Electron Microscope Study of Experimentally Shocked Pregraphitic Carbon

NASA Technical Reports Server (NTRS)

Rietmeijer, Frans J. M.

1995-01-01

A transmission electron microscope study of experimental shock metamorphism in natural pre-graphitic carbon simulates the response of the most common natural carbons to increased shock pressure. The d-spacings of this carbon are insensitive to the shock pressure and have no apparent diagnostic value, but progressive comminution occurs in response to increased shock pressure up to 59.6 GPa. The function, P = 869.1 x (size(sub minimum )(exp -0.83), describes the relationship between the minimum root-mean-square subgrain size (nm) and shock pressure (GPa). While a subgrain texture of natural pregraphitic carbons carries little information when pre-shock textures are unknown, this texture may go unnoticed as a shock metamorphic feature.

Pathophysiology and Toxicokinetic Studies of Blue-Green Algae Intoxication in the Swine Model

DTIC Science & Technology

1991-06-26

perfusion, renal perfusion, and mean arterial and central venous pressures were decreased, and portal pressure increased. Liver iron and hemoglobin indicated...the lethal dose, aortic mean pressure and central venous pressure decreased significantly, while portal venous pressure significantly increased. The...8217" recorded on a poiygraphY and logged on a hemodynamic analyzer.𔄁 Mean aortic, central venous , and portal venous pressures were determined predosing

46 CFR 154.408 - Cargo tank external pressure load.

Code of Federal Regulations, 2010 CFR

2010-10-01

... minimum internal pressure (maximum vacuum), and the maximum external pressure to which any portion of the... 46 Shipping 5 2010-10-01 2010-10-01 false Cargo tank external pressure load. 154.408 Section 154... Equipment Cargo Containment Systems § 154.408 Cargo tank external pressure load. For the calculation...

[Central pulse pressure but not brachial blood pressure is the predominant factor affecting aortic arterial stiffness].

PubMed

Xiao, Wen-Kai; Ye, Ping; Bai, Yong-Yi; Luo, Lei-Ming; Wu, Hong-Mei; Gao, Peng

2015-01-01

To investigate the differences in central hemodynamic indices between hypertensive and normotensive subjects and identify the blood pressure index that the most strongly correlate with arterial stiffness and vascular damage markers. A cohort of 820 hypertensive patients and 820 normotensive individuals matched for age and gender were enrolled in this study. We measured carotid-femoral and carotid-radial pulse wave velocity (PWV), aortic augmentation index (AIx) and central blood pressures using pulse wave analysis and applanation tonometry. Plasma homocysteine (HCY), high-sensitivity C-reactive protein (hsCRP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) were also tested in these subjects. In both hypertensive and normotensive subjects, the central systolic blood pressure (SBP) and pulse pressure (PP) were significantly lower than brachial SBP and PP; this PP amplification was significantly lower in the normotensives (9.85∓6.55 mmHg) than in the hypertensives (12.64∓6.69 mmHg), but the amplification ratios were comparable between the two groups. Blood pressure and age were closely related with aortic arterial stiffness. Compared with normotensive subjects, hypertensive subjects had higher carotid-femoral PWV and AIx, and showed significantly lowered PP amplification ratio with age. Central PP was more strongly related to arterial stiffness and vascular damage markers than the other pressure indices. Multivariate analyses revealed that carotid-femoral PWV and aortic AIx were strongly influenced by central PP but not by the mean blood pressure or brachial PP. The central PP is a more direct indicator of central arterial stiffness and a better marker of vascular aging than other blood pressure variables. These findings support the use of central blood pressure as a treatment target in future trials.

Automatic procedure for stable tetragonal or hexagonal structures: application to tetragonal Y and Cd

NASA Astrophysics Data System (ADS)

Marcus, P. M.; Jona, F.

2005-05-01

A simple effective procedure (MNP) for finding equilibrium tetragonal and hexagonal states under pressure is described and applied. The MNP procedure finds a path to minima of the Gibbs free energy G at T=0 K (G=E+pV, E=energy per atom, p=pressure, V=volume per atom) for tetragonal and hexagonal structures by using the approximate expansion of G in linear and quadratic strains at an arbitrary initial structure to find a change in the strains which moves toward a minimum of G. Iteration automatically proceeds to a minimum within preset convergence criteria on the calculation of the minimum. Comparison is made with experimental results for the ground states of seven metallic elements in hexagonal close-packed (hcp), face- and body-centered cubic structures, and with a previous procedure for finding minima based on tracing G along the epitaxial Bain path (EBP) to a minimum; the MNP is more easily generalized than the EBP procedure to lower symmetry and more atoms in the unit cell. Comparison is also made with a molecular-dynamics program for crystal equilibrium structures under pressure and with CRYSTAL, a program for crystal equilibrium structures at zero pressure. Application of MNP to the elements Y and Cd, which have hcp ground states at zero pressure, finds minima of E at face-centered cubic (fcc) structure for both Y and Cd. Evaluation of all the elastic constants shows that fcc Y is stable, hence a metastable phase, but fcc Cd is unstable.

49 CFR 179.220-6 - Thickness of plates.

Code of Federal Regulations, 2010 CFR

2010-10-01

... heads; P = Minimum required bursting pressure in psig; S = Minimum tensile strength of plate material in p.s.i. as prescribed in AAR Specifications for Tank Cars, appendix M, Table M1; t = Minimum... seamless heads; L = Main inside radius to which head is dished, measured on concave side in inches; P...

Transfer function-derived central pressure and cardiovascular disease events: the Framingham Heart Study.

PubMed

Mitchell, Gary F; Hwang, Shih-Jen; Larson, Martin G; Hamburg, Naomi M; Benjamin, Emelia J; Vasan, Ramachandran S; Levy, Daniel; Vita, Joseph A

2016-08-01

Relations between central pulse pressure (PP) or pressure amplification and major cardiovascular disease (CVD) events are controversial. Estimates of central aortic pressure derived using radial artery tonometry and a generalized transfer function may better predict CVD risk beyond the predictive value of brachial SBP. Augmentation index, central SBP, central PP, and central-to-peripheral PP amplification were evaluated using radial artery tonometry and a generalized transfer function as implemented in the SphygmoCor device (AtCor Medical, Itasca, Illinois, USA). We used proportional hazards models to examine relations between central hemodynamics and first-onset major CVD events in 2183 participants (mean age 62 years, 58% women) in the Framingham Heart Study. During median follow-up of 7.8 (limits 0.2-8.9) years, 149 participants (6.8%) had an incident event. Augmentation index (P = 0.6), central aortic systolic pressure (P = 0.20), central aortic PP (P = 0.24), and PP amplification (P = 0.15) were not related to CVD events in multivariable models that adjusted for age, sex, brachial cuff systolic pressure, use of antihypertensive therapy, total and high-density lipoprotein cholesterol concentrations, smoking, and presence of diabetes. In a model that included standard risk factors, model fit was improved (P = 0.03) when brachial systolic pressure was added after central, whereas model fit was not improved (P = 0.30) when central systolic pressure was added after brachial. After considering standard risk factors, including brachial cuff SBP, augmentation index, central PP and PP amplification derived using radial artery tonometry, and a generalized transfer function were not predictive of CVD risk.

Influence of central venous pressure upon sinus node responses to arterial baroreflex stimulation in man

NASA Technical Reports Server (NTRS)

Mark, A. L.; Takeshita, A.; Eckberg, D. L.; Abboud, F. M.

1978-01-01

Measurements were made of sinus node responses to arterial baroreceptor stimulation with phenylephrine injection or neck suction, before and during changes of central venous pressure provoked by lower body negative pressure or leg and lower truck elevation. Variations of central venous pressure between 1.1 and 9.0 mm Hg did not influence arterial baroreflex mediated bradycardia. Baroreflex sinus node responses were augmented by intravenous propranolol, but the level of responses after propranolol was comparable during the control state, lower body negative pressure, and leg and trunk elevation. Sinus node responses to very brief baroreceptor stimuli applied during the transitions of central venous pressure also were comparable in the three states. The authors conclude that physiological variations of central venous pressure do not influence sinus node responses to arterial baroreceptor stimulation in man.

Impacts of coronary artery eccentricity on macro-recirculation and pressure drops using computational fluid dynamics

NASA Astrophysics Data System (ADS)

Poon, Eric; Thondapu, Vikas; Barlis, Peter; Ooi, Andrew

2017-11-01

Coronary artery disease remains a major cause of mortality in developed countries, and is most often due to a localized flow-limiting stenosis, or narrowing, of coronary arteries. Patients often undergo invasive procedures such as X-ray angiography and fractional flow reserve to diagnose flow-limiting lesions. Even though such diagnostic techniques are well-developed, the effects of diseased coronary segments on local flow are still poorly understood. Therefore, this study investigated the effect of irregular geometries of diseased coronary segments on the macro-recirculation and local pressure minimum regions. We employed an idealized coronary artery model with a diameter of stenosis of 75%. By systematically adjusting the eccentricity and the asymmetry of the coronary stenosis, we uncovered an increase in macro-recirculation size. Most importantly, the presence of this macro-recirculation signifies a local pressure minimum (identified by λ2 vortex identification method). This local pressure minimum has a profound effect on the pressure drops in both longitudinal and planar directions, which has implications for diagnosis and treatment of coronary artery disease. Supported by Australian Research Council LP150100233 and National Computational Infrastructure m45.

Pressure Testing of a Minimum Gauge PRSEUS Panel

NASA Technical Reports Server (NTRS)

Lovejoy, Andrew J.; Rouse, Marshall; Linton, Kim A.; Li, Victor P.

2011-01-01

Advanced aircraft configurations that have been developed to increase fuel efficiency require advanced, novel structural concepts capable of handling the unique load conditions that arise. One such concept is the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) developed by the Boeing Company. The PRSEUS concept is being investigated by NASA s Environmentally Responsible Aviation (ERA) Program for use in a hybrid-wing body (HWB) aircraft. This paper summarizes the analysis and test of a PRSEUS panel subjected to internal pressure, the first such pressure test for this structural concept. The pressure panel used minimum gauge skin, with stringer and frame configurations consistent with previous PRSEUS tests. Analysis indicated that for the minimum gauge skin panel, the stringer locations exhibit fairly linear response, but the skin bays between the stringers exhibit nonlinear response. Excellent agreement was seen between nonlinear analysis and test results in the critical portion at the center of the panel. The pristine panel was capable of withstanding the required 18.4 psi pressure load condition without exhibiting any damage. The impacted panel was capable of withstanding a pressure load in excess of 28 psi before initial failure occurred at the center stringer, and the panel was capable of sustaining increased pressure load after the initial failure. This successful PRSEUS panel pressure panel test was a critical step in the building block approach for enabling the use of this advanced structural concept on future aircraft, such as the HWB.

External jugular venous pressure as an alternative to conventional central venous pressure in right lobe donor hepatectomies.

PubMed

Abdullah, Mohamed Hussein; Soliman, Hossam El Deen; Morad, Wessam Saber

2011-12-01

Many centers have adopted central vein cannulation both for central venous pressure monitoring and fluid administration for right hepatectomy in living-liver donors. However, use of central venous catheters is associated with adverse events that are hazardous to patients and expensive to treat. This study sought to examine the use of external jugular venous pressure as an alternative to conventional central venous pressure in right lobe donor hepatectomies Forty ASA grade I adult living liver-donors without a known history of significant cardiac or pulmonary diseases were enrolled in this prospective observational study. Paired measurement of venous pressures (external jugular venous pressure and internal jugular venous pressure) were taken at the following times: after induction of anesthesia, 30 minutes after skin incision, during right lobe mobilization (every 15 minutes), during hepatic transaction (every 15 minutes), after right lobe resection (every 15 minutes), and after abdominal closure. Paired measurements were equal in 47.5%, 53.5%, 61.5%, 46.3%, and 52.5% for after induction, after skin incision, right lobe mobilization, right lobe transection, after resection, and before abdominal closure periods. However, all measurements were within acceptable limits of bias measurements (± 2 mm Hg). Central venous pressure catheter placement can be avoided and replaced by a less-invasive method such as external jugular venous pressure (which gave an acceptable estimate of central venous pressure in all phases of right lobe resection) in living-donor liver transplant and allowed equivalent monitor even during fluid restriction phases.

A variable pressure method for characterizing nanoparticle surface charge using pore sensors.

PubMed

Vogel, Robert; Anderson, Will; Eldridge, James; Glossop, Ben; Willmott, Geoff

2012-04-03

A novel method using resistive pulse sensors for electrokinetic surface charge measurements of nanoparticles is presented. This method involves recording the particle blockade rate while the pressure applied across a pore sensor is varied. This applied pressure acts in a direction which opposes transport due to the combination of electro-osmosis, electrophoresis, and inherent pressure. The blockade rate reaches a minimum when the velocity of nanoparticles in the vicinity of the pore approaches zero, and the forces on typical nanoparticles are in equilibrium. The pressure applied at this minimum rate can be used to calculate the zeta potential of the nanoparticles. The efficacy of this variable pressure method was demonstrated for a range of carboxylated 200 nm polystyrene nanoparticles with different surface charge densities. Results were of the same order as phase analysis light scattering (PALS) measurements. Unlike PALS results, the sequence of increasing zeta potential for different particle types agreed with conductometric titration.

Corneal Thickness Profile and Associations in Chinese Children Aged 7 to 15 Years Old.

PubMed

Ma, Yingyan; Zhu, Xiaofeng; He, Xiangui; Lu, Lina; Zhu, Jianfeng; Zou, Haidong

2016-01-01

Corneal thickness (CT) maps of the central (2-mm diameter), para-central (2 to 5-mm diameter), peripheral (5 to 6-mm diameter), and minimum (5-mm diameter) cornea were measured in normal Chinese school children aged 7 to 15 years old using Fourier-domain optical coherence tomography. Multiple regression analyses were performed to explore the effect of associated factors [age, gender, refraction, axial length and corneal curvature radius (CCR)] on CT and the relationship between central corneal thickness (CCT) and intraocular pressure (IOP). A total of 1228 eyes from 614 children were analyzed. The average CCT was 532.96 ± 28.33 μm for right eyes and 532.70 ±28.45 μm for left eyes. With a 10 μm increase in CCT, the IOP was elevated by 0.37 mm Hg, as measured by noncontact tonometry. The CT increased gradually from the center to the periphery. The superior and superior nasal regions had the thickest CTs, while the thinnest points were primarily located in the inferior temporal cornea. The CCT was associated with CCR (p = 0.008) but not with gender (p = 0.075), age (p = 0.286), axial length (p = 0.405), or refraction (p = 0.985). In the para-central region and the peripheral cornea, increased CT was associated with younger age, male gender, and a flatter cornea.

A Contrastive Study of Determiner Usage in EST Research Articles

ERIC Educational Resources Information Center

Master, Peter

1993-01-01

The determiners in English include three categories: predeterminers, central determiners, and postdeterminers. The focus of the present study is the central determiners because they comprise the largest group and because a minimum of one central determiner is required in the generation of any noun phrase. Furthermore, the central determiners have…

Central arterial pressure assessment with intensity POF sensor

NASA Astrophysics Data System (ADS)

Leitão, Cátia; Gonçalves, Steve; Antunes, Paulo; Bastos, José M.; Pinto, João. L.; André, Paulo

2015-09-01

The central pressure monitoring is considered a new key factor in hypertension assessment and cardiovascular prevention. In this work, it is presented the central arterial systolic pressure assessment with an intensity based POF sensor. The device was tested in four subjects, and stable pulse waves were obtained, allowing the calculation of the central pressure for all the subjects. The results shown that the sensor performs reliably, being a simple and low-cost solution to the intended application.

49 CFR 195.300 - Scope.

Code of Federal Regulations, 2012 CFR

2012-10-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Pressure Testing § 195.300 Scope. This subpart prescribes minimum requirements for the pressure...

49 CFR 195.300 - Scope.

Code of Federal Regulations, 2013 CFR

2013-10-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Pressure Testing § 195.300 Scope. This subpart prescribes minimum requirements for the pressure...

49 CFR 195.300 - Scope.

Code of Federal Regulations, 2011 CFR

2011-10-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Pressure Testing § 195.300 Scope. This subpart prescribes minimum requirements for the pressure...

49 CFR 195.300 - Scope.

Code of Federal Regulations, 2010 CFR

2010-10-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Pressure Testing § 195.300 Scope. This subpart prescribes minimum requirements for the pressure...

49 CFR 195.300 - Scope.

Code of Federal Regulations, 2014 CFR

2014-10-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Pressure Testing § 195.300 Scope. This subpart prescribes minimum requirements for the pressure...

49 CFR 178.45 - Specification 3T seamless steel cylinder.

Code of Federal Regulations, 2011 CFR

2011-10-01

..., and service pressure. A DOT 3T cylinder is a seamless steel cylinder with a minimum water capacity of...) Wall thickness. The minimum wall thickness must be such that the wall stress at the minimum specified... the physical tests required in paragraphs (j) and (k) of this section. A wall stress of more than 90...

Impact of calibration on estimates of central blood pressures.

PubMed

Soender, T K; Van Bortel, L M; Møller, J E; Lambrechtsen, J; Hangaard, J; Egstrup, K

2012-12-01

Using the Sphygmocor device it is recommended that the radial pressure wave is calibrated for brachial systolic blood pressure (SBP) and diastolic blood pressure (DBP). However it has been suggested that brachial-to-radial pressure amplification causes underestimation of central blood pressures (BPs) using this calibration. In the present study we examined if different calibrations had an impact on estimates of central BPs and on the clinical interpretation of our results. On the basis of ambulatory BP measurements, patients were categorized into patients with controlled, uncontrolled or resistant hypertension. We first calibrated the radial pressure wave as recommended and afterwards recalibrated the same pressure wave using brachial DBP and calculated mean arterial pressure. Recalibration of the pressure wave generated significantly higher estimates of central SBP (P=0.0003 and P<0.0001 at baseline and P=0.0001 and P=0.0002 after 6 months). Using recommended calibration we found a significant change in central SBP in both treatment groups (P=0.05 and P=0.01), however, after recalibrating significance was lost in patients with resistant hypertension (P=0.15). We conclude that calibration with DBP and mean arterial pressure produces higher estimates of central BPs than recommended calibration. The present study also shows that this difference between the two calibration methods can produce more than a systematic error and has an impact on interpretation of clinical results.

Stability of DIII-D high-performance, negative central shear discharges

DOE PAGES

Hanson, Jeremy M.; Berkery, John W.; Bialek, James M.; ...

2017-03-20

Tokamak plasma experiments on the DIII-D device demonstrate high-performance, negative central shear (NCS) equilibria with enhanced stability when the minimum safety factor q min exceeds 2, qualitatively confirming theoretical predictions of favorable stability in the NCS regime. The discharges exhibit good confinement with an L-mode enhancement factor H 89 = 2.5, and are ultimately limited by the ideal-wall external kink stability boundary as predicted by ideal MHD theory, as long as tearing mode (TM) locking events, resistive wall modes (RWMs), and internal kink modes are properly avoided or controlled. Although the discharges exhibit rotating TMs, locking events are avoided asmore » long as a threshold minimum safety factor value q min > 2 is maintained. Fast timescale magnetic feedback control ameliorates RWM activity, expanding the stable operating space and allowing access to β N values approaching the ideal-wall limit. Quickly growing and rotating instabilities consistent with internal kink mode dynamics are encountered when the ideal-wall limit is reached. The RWM events largely occur between the no- and ideal-wall pressure limits predicted by ideal MHD. However, evaluating kinetic contributions to the RWM dispersion relation results in a prediction of passive stability in this regime due to high plasma rotation. In addition, the ideal MHD stability analysis predicts that the ideal-wall limit can be further increased to β N > 4 by broadening the current profile. Furthermore, this path toward improved stability has the potential advantage of being compatible with the bootstrap-dominated equilibria envisioned for advanced tokamak (AT) fusion reactors.« less

Stability of DIII-D high-performance, negative central shear discharges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanson, Jeremy M.; Berkery, John W.; Bialek, James M.

Tokamak plasma experiments on the DIII-D device demonstrate high-performance, negative central shear (NCS) equilibria with enhanced stability when the minimum safety factor q min exceeds 2, qualitatively confirming theoretical predictions of favorable stability in the NCS regime. The discharges exhibit good confinement with an L-mode enhancement factor H 89 = 2.5, and are ultimately limited by the ideal-wall external kink stability boundary as predicted by ideal MHD theory, as long as tearing mode (TM) locking events, resistive wall modes (RWMs), and internal kink modes are properly avoided or controlled. Although the discharges exhibit rotating TMs, locking events are avoided asmore » long as a threshold minimum safety factor value q min > 2 is maintained. Fast timescale magnetic feedback control ameliorates RWM activity, expanding the stable operating space and allowing access to β N values approaching the ideal-wall limit. Quickly growing and rotating instabilities consistent with internal kink mode dynamics are encountered when the ideal-wall limit is reached. The RWM events largely occur between the no- and ideal-wall pressure limits predicted by ideal MHD. However, evaluating kinetic contributions to the RWM dispersion relation results in a prediction of passive stability in this regime due to high plasma rotation. In addition, the ideal MHD stability analysis predicts that the ideal-wall limit can be further increased to β N > 4 by broadening the current profile. Furthermore, this path toward improved stability has the potential advantage of being compatible with the bootstrap-dominated equilibria envisioned for advanced tokamak (AT) fusion reactors.« less

Experiments on 1,000 km/s flyer acceleration and collisions

NASA Astrophysics Data System (ADS)

Karasik, Max; Weaver, J. L.; Aglitskiy, Y.; Kehne, D. M.; Zalesak, S. T.; Velikovich, A. L.; Oh, J.; Serlin, V.; Obenschain, S. P.

2012-10-01

We will present results from follow-on experiments to the record-high velocities achieved using the ultra-uniform deep-uv drive of the Nike KrF laser [Karasik et al, Phys. Plasmas 17, 056317 (2010)], in which highly accelerated planar foils of deuterated polystyrene were made to collide with a witness foil to produce ˜1 Gbar shock pressures and result in heating of matter to thermonuclear temperatures. Such velocities may indicate a path to lower minimum energy required for central ignition. Still higher velocities and higher target densities are required for impact fast ignition. New results give velocity of >1,100 km/s achieved through improvements in pulseshaping. Variation of second foil parameters results in significant change in fusion neutron production on impact. In-flight target density is inferred from target heating upon collision via DD neutron time-of-flight ion temperature measurement. Availability of pressures generated by collisions of such highly accelerated flyers may provide an experimental platform for study of matter at extreme conditions. Work is supported by US DOE (NNSA).

Gender-specific association of the plasminogen activator inhibitor-1 4G/5G polymorphism with central arterial blood pressure.

PubMed

Björck, Hanna M; Eriksson, Per; Alehagen, Urban; De Basso, Rachel; Ljungberg, Liza U; Persson, Karin; Dahlström, Ulf; Länne, Toste

2011-07-01

The functional plasminogen activator inhibitor-1 (PAI-1) 4G/5G polymorphism has previously been associated with hypertension. In recent years, central blood pressure, rather than brachial has been argued a better measure of cardiovascular damage and clinical outcome. The aim of this study was to investigate the possible influence of the 4G/5G polymorphism on central arterial blood pressure in a cohort of elderly individuals. We studied 410 individuals, 216 men and 194 women, aged 70-88. Central pressures and pulse waveforms were calculated from the radial artery pressure waveform by the use of the SphygmoCor system and a generalized transfer function. Brachial pressure was recorded using oscillometric technique (Dinamap, Critikon, Tampa, FL). PAI-1 antigen was determined in plasma. The results showed that central pressures were higher in women carrying the PAI-1 4G/4G genotype compared to female carriers of the 5G/5G genotype, (P = 0.025, P = 0.002, and P = 0.002 for central systolic-, diastolic-, and mean arterial pressure, respectively). The association remained after adjustment for potentially confounding factors related to hypertension. No association of the PAI-1 genotype with blood pressure was found in men. Multiple regression analysis revealed an association between PAI-1 genotype and plasma PAI-1 levels (P = 0.048). Our findings show a gender-specific association of the PAI-1 4G/5G polymorphism with central arterial blood pressure. The genotype effect was independent of other risk factors related to hypertension, suggesting that impaired fibrinolytic potential may play an important role in the development of central hypertension in women.

The association of remotely-sensed outdoor temperature with blood pressure levels in REGARDS: a cross-sectional study of a large, national cohort of African-American and white participants

PubMed Central

2011-01-01

Background Evidence is mounting regarding the clinically significant effect of temperature on blood pressure. Methods In this cross-sectional study the authors obtained minimum and maximum temperatures and their respective previous week variances at the geographic locations of the self-reported residences of 26,018 participants from a national cohort of blacks and whites, aged 45+. Linear regression of data from 20,623 participants was used in final multivariable models to determine if these temperature measures were associated with levels of systolic or diastolic blood pressure, and whether these relations were modified by stroke-risk region, race, education, income, sex hypertensive medication status, or age. Results After adjustment for confounders, same-day maximum temperatures 20°F lower had significant associations with 1.4 mmHg (95% CI: 1.0, 1.9) higher systolic and 0.5 mmHg (95% CI: 0.3, 0.8) higher diastolic blood pressures. Same-day minimum temperatures 20°F lower had a significant association with 0.7 mmHg (95% CI: 0.3, 1.0) higher systolic blood pressures but no significant association with diastolic blood pressure differences. Maximum and minimum previous-week temperature variabilities showed significant but weak relationships with blood pressures. Parameter estimates showed effect modification of negligible magnitude. Conclusions This study found significant associations between outdoor temperature and blood pressure levels, which remained after adjustment for various confounders including season. This relationship showed negligible effect modification. PMID:21247466

US Army Institute of Surgical Research Annual Research Progress Report for Fiscal Year 1987.

DTIC Science & Technology

1987-10-01

oases, respiratory rate, chest roentgenograms), cardiovascular (blood pressure, central venous pressure, cardiac output), and renal (urine output, urine...Monitoring includes the precordial and/or esophageal stethoscope, peripheral pulse, blood pressure, central venous pressure, Swan-Ganz catheter... central venous , peripheral venous , and Swan-Ganz (7F, American Edward Laboratories, Irvine CA) catheters and an esophageal balloon were inserted. After a 2

The association between brain-derived neurotrophic factor and central pulse pressure after an oral glucose tolerance test.

PubMed

Lee, I-Te; Chen, Chen-Huan; Wang, Jun-Sing; Fu, Chia-Po; Lee, Wen-Jane; Liang, Kae-Woei; Lin, Shih-Yi; Sheu, Wayne Huey-Herng

2018-01-01

Arterial stiffening blunts postprandial vasodilatation. We hypothesized that brain-derived neurotrophic factor (BDNF) may modulate postprandial central pulse pressure, a surrogate marker for arterial stiffening. A total of 82 non-diabetic subjects received a 75-g oral glucose tolerance test (OGTT) after overnight fasting. Serum BDNF concentrations were determined at 0, 30, and 120min to calculate the area under the curve (AUC). Brachial and central blood pressures were measured using a noninvasive central blood pressure monitor before blood withdrawals at 0 and 120min. With the median AUC of BDNF of 45(ng/ml)∗h as the cutoff value, the central pulse pressure after glucose intake was significantly higher in the subjects with a low BDNF than in those with a high BDNF (63±16 vs. 53±11mmHg, P=0.003), while the brachial pulse pressure was not significantly different between the 2 groups (P=0.099). In a multivariate linear regression model, a lower AUC of BDNF was an independent predictor of a higher central pulse pressure after oral glucose intake (linear regression coefficient-0.202, 95% confidence interval-0.340 to -0.065, P=0.004). After oral glucose challenge, a lower serum BDNF response is significantly associated with a higher central pulse pressure. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of beta-1-blocker, nebivolol, on central aortic pressure and arterial stiffness in patients with essential hypertension.

PubMed

Soanker, Radhika; Naidu, M U R; Raju, Sree Bhushan; Prasad, A Krishna; Rao, T Ramesh Kumar

2012-05-01

Blood pressure (BP) reduction is the major determinant of benefit provided by antihypertensive treatment. Although different drugs reduce peripheral BP to some extent, there may be a significant difference in their effect on central BP reduction. It has been shown that beta-blockers are efficient in reducing peripheral, but not central BP. This study was done to assess the effect of beta-1-blocker, nebivolol, in patients with essential hypertension on central aortic pressures and arterial stiffness. In this single arm, open-labeled study, 13 patients were given nebivolol, 5 mg orally once daily for 15 days. Primary outcome was change in central aortic pressure, and other measures of efficacy included changes in brachial BP, augmentation index (AIx%), AIx%@75 HR, augmentation pressure (AP), heart rate (HR), and carotid femoral pulse wave velocity (PWVcf). Nebivolol 5 mg significantly reduced central aortic pressures [systolic BP, 131.5-111.6 mmHg; diastolic BP, 96.3-81.7 mmHg; Mean Arterial Pressure (MAP), 111.3-94.0 mmHg (all P<0.0001), and Pulse Pressure (PP), 35.2-29.7 mmHg (P<0.01)]. AIx%@75 HR reduced from 29 to 21.6 (P<0.001) and PWVcf reduced from 8.6 to 7.2 m/s (P<0.001). One subject was lost to followup. Nebivolol 5 mg demonstrated antihypertensive efficacy in patients with essential hypertension by reducing not only peripheral brachial pressures, but also significantly reducing central aortic pressures, augmentation index, and carotid femoral pulse wave velocity, which is the marker of arterial stiffness.

Maternal Blood Pressure During Pregnancy and Early Childhood Blood Pressures in the Offspring

PubMed Central

Lim, Wai-Yee; Lee, Yung-Seng; Yap, Fabian Kok-Peng; Aris, Izzudin Mohd; Ngee, Lek; Meaney, Michael; Gluckman, Peter D.; Godfrey, Keith M.; Kwek, Kenneth; Chong, Yap-Seng; Saw, Seang-Mei; Pan, An

2015-01-01

Abstract Although epidemiological studies suggest that offspring of women with preeclampsia are at increased risk to higher blood pressures and cardiovascular disease, little is known about the nature of blood pressures between the mother and her offspring. As blood pressures comprise of both pulsatile (systolic blood pressure [SBP] and pulse pressure [PP]) and stable (diastolic blood pressure [DBP]) components, and they differ between central and peripheral sites, we sought to examine maternal peripheral and central blood pressure components in relation to offspring early childhood blood pressures. A prospective birth cohort of 567 Chinese, Malay, and Indian mother–offspring with complete blood pressure information were studied. Maternal brachial artery SBP, DBP, and PP were measured at 26 to 28 weeks gestation; and central SBP and PP were estimated from radial artery waveforms. Offspring brachial artery SBP, DBP, and PP were measured at 3 years of age. Associations between continuous variables of maternal blood pressures (peripheral SBP, DBP, PP, central SBP, and PP) and offspring blood pressures (peripheral SBP, DBP, and PP) were examined using multiple linear regression with adjustment for maternal characteristics (age, education level, parity, smoking status, alcohol consumption and physical activity during pregnancy, and pre-pregnancy BMI) and offspring characteristics (sex, ethnicity, BMI, and height at 3 years of age). In the multivariate models, offspring peripheral SBP increased by 0.08 (95% confidence interval 0.00–0.17, P = 0.06) mmHg with every 1-mmHg increase in maternal central SBP, and offspring peripheral PP increased by 0.10 (0.01–0.18, P = 0.03) mmHg for every 1-mmHg increase in maternal central PP. The relations of maternal-offspring peripheral blood pressures (SBP, DBP, and PP) were positive but not statistically significant, and the corresponding values were 0.05 (−0.03 to 0.13; P = 0.21), 0.03 (−0.04 to 0.10; P = 0.35), and 0.05 (−0.02 to 0.13; P = 0.14), respectively. Maternal central pulsatile blood pressure components (SBP and PP) during pregnancy are associated with higher blood pressures in the offspring. This positive correlation is already evident at 3-years old. Studies are needed to further evaluate the effects of maternal central pulsatile blood pressure components during pregnancy and long-term cardiovascular health in the offspring. PMID:26559279

49 CFR 192.627 - Tapping pipelines under pressure.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false Tapping pipelines under pressure. 192.627 Section... NATURAL AND OTHER GAS BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Operations § 192.627 Tapping pipelines under pressure. Each tap made on a pipeline under pressure must be performed by a crew qualified to make...

The pressure recovery ratio: The invasive index of LV relaxation during filling. Model-based prediction with in-vivo validation.

PubMed

Zhang, Wei; Shmuylovich, Leonid; Kovacs, Sandor J

2009-01-01

Using a simple harmonic oscillator model (PDF formalism), every early filling E-wave can be uniquely described by a set of parameters, (x(0), c, and k). Parameter c in the PDF formalism is a damping or relaxation parameter that measures the energy loss during the filling process. Based on Bernoulli's equation and kinematic modeling, we derived a causal correlation between the relaxation parameter c in the PDF formalism and a feature of the pressure contour during filling - the pressure recovery ratio defined by the left ventricular pressure difference between diastasis and minimum pressure, normalized to the pressure difference between a fiducial pressure and minimum pressure [PRR = (P(Diastasis)-P(Min))/(P(Fiducial)-P(Min))]. We analyzed multiple heart beats from one human subject to validate the correlation. Further validation among more patients is warranted. PRR is the invasive causal analogue of the noninvasive E-wave relaxation parameter c. PRR has the potential to be calculated using automated methodology in the catheterization lab in real time.

Cosmic Ray Hits in the Central Nervous System at Solar Maximum

NASA Technical Reports Server (NTRS)

Curtis, S. B.; Vazquez, M. E.; Wilson, J. W.; Atwell, W.; Kin, M.-H. Y.

2000-01-01

It has been suggested that a manned mission to Mars be launched at solar maximum rather than at solar minimum to minimize the radiation exposure to galactic cosmic rays. It is true that the number of hits from highly ionizing particles to critical regions in the brain will be less at solar maximum, and it is of interest to estimate how much less. We present here calculations for several sites within the brain from iron ions (z = 26) and from particles with charge, z, greater than or equal to 15. The same shielding configurations and sites in the brain used in an earlier paper for solar minimum are employed so that direct comparison of results between the two solar activity conditions can be made. A simple pressure-vessel wall and an equipment room onboard a spacecraft are chosen as shielding examples. In the equipment room, typical results for the thalamus are that the probability of any particles with z greater than or equal to 15 and from 2.3 percent to 1.3 percent for iron ions. The extra shielding provided in the equipment room makes little difference in these numbers. We conclude that this decrease in hit frequency (less than a factor of two) does not provide a compelling reason to avoid solar minimum for a manned mission to Mars. This conclusion could be revised, however, if a very small number of hits is found to cause critical malfunction within the brain.

On pressure measurement and seasonal pressure variations during the Phoenix mission

NASA Astrophysics Data System (ADS)

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

2010-03-01

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

49 CFR 173.337 - Nitric oxide.

Code of Federal Regulations, 2010 CFR

2010-10-01

... charged to a pressure of not more than 5,170 kPa (750 psi) at 21 °C (70 °F). Transportation of nitric... with a minimum test pressure of 200 bar. The maximum working pressure of the cylinder must not exceed 50 bar. The pressure in the cylinder at 65 °C (149 °F) may not exceed the test pressure. The use of...

49 CFR 173.337 - Nitric oxide.

Code of Federal Regulations, 2014 CFR

2014-10-01

... charged to a pressure of not more than 5,170 kPa (750 psi) at 21 °C (70 °F). Transportation of nitric... with a minimum test pressure of 200 bar. The maximum working pressure of the cylinder must not exceed 50 bar. The pressure in the cylinder at 65 °C (149 °F) may not exceed the test pressure. The use of...

49 CFR 173.337 - Nitric oxide.

Code of Federal Regulations, 2011 CFR

2011-10-01

... charged to a pressure of not more than 5,170 kPa (750 psi) at 21 °C (70 °F). Transportation of nitric... with a minimum test pressure of 200 bar. The maximum working pressure of the cylinder must not exceed 50 bar. The pressure in the cylinder at 65 °C (149 °F) may not exceed the test pressure. The use of...

49 CFR 173.337 - Nitric oxide.

Code of Federal Regulations, 2012 CFR

2012-10-01

... charged to a pressure of not more than 5,170 kPa (750 psi) at 21 °C (70 °F). Transportation of nitric... with a minimum test pressure of 200 bar. The maximum working pressure of the cylinder must not exceed 50 bar. The pressure in the cylinder at 65 °C (149 °F) may not exceed the test pressure. The use of...

49 CFR 173.337 - Nitric oxide.

Code of Federal Regulations, 2013 CFR

2013-10-01

... charged to a pressure of not more than 5,170 kPa (750 psi) at 21 °C (70 °F). Transportation of nitric... with a minimum test pressure of 200 bar. The maximum working pressure of the cylinder must not exceed 50 bar. The pressure in the cylinder at 65 °C (149 °F) may not exceed the test pressure. The use of...

46 CFR 62.25-20 - Instrumentation, alarms, and centralized stations.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Instrumentation, alarms, and centralized stations. 62.25... Instrumentation, alarms, and centralized stations. (a) General. Minimum instrumentation and alarms required for specific types of automated vital systems are listed in Table 62.35-50. (b) Instrumentation Location. (1...

46 CFR 62.25-20 - Instrumentation, alarms, and centralized stations.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Instrumentation, alarms, and centralized stations. 62.25... Instrumentation, alarms, and centralized stations. (a) General. Minimum instrumentation and alarms required for specific types of automated vital systems are listed in Table 62.35-50. (b) Instrumentation Location. (1...

46 CFR 62.25-20 - Instrumentation, alarms, and centralized stations.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Instrumentation, alarms, and centralized stations. 62.25... Instrumentation, alarms, and centralized stations. (a) General. Minimum instrumentation and alarms required for specific types of automated vital systems are listed in Table 62.35-50. (b) Instrumentation Location. (1...

46 CFR 62.25-20 - Instrumentation, alarms, and centralized stations.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 2 2013-10-01 2013-10-01 false Instrumentation, alarms, and centralized stations. 62.25... Instrumentation, alarms, and centralized stations. (a) General. Minimum instrumentation and alarms required for specific types of automated vital systems are listed in Table 62.35-50. (b) Instrumentation Location. (1...

Modeling Seasonal Influenza Transmission and Its Association with Climate Factors in Thailand Using Time-Series and ARIMAX Analyses.

PubMed

Chadsuthi, Sudarat; Iamsirithaworn, Sopon; Triampo, Wannapong; Modchang, Charin

2015-01-01

Influenza is a worldwide respiratory infectious disease that easily spreads from one person to another. Previous research has found that the influenza transmission process is often associated with climate variables. In this study, we used autocorrelation and partial autocorrelation plots to determine the appropriate autoregressive integrated moving average (ARIMA) model for influenza transmission in the central and southern regions of Thailand. The relationships between reported influenza cases and the climate data, such as the amount of rainfall, average temperature, average maximum relative humidity, average minimum relative humidity, and average relative humidity, were evaluated using cross-correlation function. Based on the available data of suspected influenza cases and climate variables, the most appropriate ARIMA(X) model for each region was obtained. We found that the average temperature correlated with influenza cases in both central and southern regions, but average minimum relative humidity played an important role only in the southern region. The ARIMAX model that includes the average temperature with a 4-month lag and the minimum relative humidity with a 2-month lag is the appropriate model for the central region, whereas including the minimum relative humidity with a 4-month lag results in the best model for the southern region.

Fuel control for gas turbine with continuous pilot flame

DOEpatents

Swick, Robert M.

1983-01-01

An improved fuel control for a gas turbine engine having a continuous pilot flame and a fuel distribution system including a pump drawing fuel from a source and supplying a line to the main fuel nozzle of the engine, the improvement being a control loop between the pump outlet and the pump inlet to bypass fuel, an electronically controlled throttle valve to restrict flow in the control loop when main nozzle demand exists and to permit substantially unrestricted flow without main nozzle demand, a minimum flow valve in the control loop downstream of the throttle valve to maintain a minimum pressure in the loop ahead of the flow valve, a branch tube from the pilot flame nozzle to the control loop between the throttle valve and the minimum flow valve, an orifice in the branch tube, and a feedback tube from the branch tube downstream of the orifice to the minimum flow valve, the minimum flow valve being operative to maintain a substantially constant pressure differential across the orifice to maintain constant fuel flow to the pilot flame nozzle.

49 CFR 192.359 - Customer meter installations: Operating pressure.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false Customer meter installations: Operating pressure... SAFETY TRANSPORTATION OF NATURAL AND OTHER GAS BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Customer Meters, Service Regulators, and Service Lines § 192.359 Customer meter installations: Operating pressure...

30 CFR 1206.151 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... any production month, a contract must satisfy this definition for that month, as well as when the... lease production to a central accumulation and/or treatment point on the lease, unit or communitized... the lessee's production and to market that production. Minimum royalty means that minimum amount of...

30 CFR 1206.151 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... interests regarding that contract. To be considered arm's length for any production month, a contract must.... Gathering means the movement of lease production to a central accumulation and/or treatment point on the... the lessee's production and to market that production. Minimum royalty means that minimum amount of...

30 CFR 1206.151 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... interests regarding that contract. To be considered arm's length for any production month, a contract must.... Gathering means the movement of lease production to a central accumulation and/or treatment point on the... the lessee's production and to market that production. Minimum royalty means that minimum amount of...

30 CFR 206.151 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... interests regarding that contract. To be considered arm's length for any production month, a contract must.... Gathering means the movement of lease production to a central accumulation and/or treatment point on the... the lessee's production and to market that production. Minimum royalty means that minimum amount of...

Retrieving air humidity, global solar radiation, and reference evapotranspiration from daily temperatures: development and validation of new methods for Mexico. Part I: humidity

NASA Astrophysics Data System (ADS)

Lobit, P.; López Pérez, L.; Lhomme, J. P.; Gómez Tagle, A.

2017-07-01

This study evaluates the dew point method (Allen et al. 1998) to estimate atmospheric vapor pressure from minimum temperature, and proposes an improved model to estimate it from maximum and minimum temperature. Both methods were evaluated on 786 weather stations in Mexico. The dew point method induced positive bias in dry areas but also negative bias in coastal areas, and its average root mean square error for all evaluated stations was 0.38 kPa. The improved model assumed a bi-linear relation between estimated vapor pressure deficit (difference between saturated vapor pressure at minimum and average temperature) and measured vapor pressure deficit. The parameters of these relations were estimated from historical annual median values of relative humidity. This model removed bias and allowed for a root mean square error of 0.31 kPa. When no historical measurements of relative humidity were available, empirical relations were proposed to estimate it from latitude and altitude, with only a slight degradation on the model accuracy (RMSE = 0.33 kPa, bias = -0.07 kPa). The applicability of the method to other environments is discussed.

A study to evaluate STS heads-up ascent trajectory performance employing a minimum-Hamiltonian optimization strategy

NASA Technical Reports Server (NTRS)

Sinha, Sujit

1988-01-01

A study was conducted to evaluate the performance implications of a heads-up ascent flight design for the Space Transportation System, as compared to the current heads-down flight mode. The procedure involved the use of the Minimum Hamiltonian Ascent Shuttle Trajectory Evaluation Program, which is a three-degree-of-freedom moment balance simulation of shuttle ascent. A minimum-Hamiltonian optimization strategy was employed to maximize injection weight as a function of maximum dynamic pressure constraint and Solid Rocket Motor burnrate. Performance Reference Mission Four trajectory groundrules were used for consistency. The major conclusions are that for heads-up ascent and a mission nominal design maximum dynamic pressure value of 680 psf, the optimum solid motor burnrate is 0.394 ips, which produces a performance enhancement of 4293 lbm relative to the baseline heads-down ascent, with 0.368 ips burnrate solid motors and a 680 psf dynamic pressure constraint. However, no performance advantage exists for heads-up flight if the current Solid Rocket Motor target burnrate of 0.368 ips is used. The advantage of heads-up ascent flight employing the current burnrate is that Space Shuttle Main Engine throttling for dynamic pressure control is not necessary.

In situ stress and pore pressure in the Kumano Forearc Basin, offshore SW Honshu from downhole measurements during riser drilling

NASA Astrophysics Data System (ADS)

Saffer, D. M.; Flemings, P. B.; Boutt, D.; Doan, M.-L.; Ito, T.; McNeill, L.; Byrne, T.; Conin, M.; Lin, W.; Kano, Y.; Araki, E.; Eguchi, N.; Toczko, S.

2013-05-01

situ stress and pore pressure are key parameters governing rock deformation, yet direct measurements of these quantities are rare. During Integrated Ocean Drilling Program (IODP) Expedition #319, we drilled through a forearc basin at the Nankai subduction zone and into the underlying accretionary prism. We used the Modular Formation Dynamics Tester tool (MDT) for the first time in IODP to measure in situ minimum stress, pore pressure, and permeability at 11 depths between 729.9 and 1533.9 mbsf. Leak-off testing at 708.6 mbsf conducted as part of drilling operations provided a second measurement of minimum stress. The MDT campaign included nine single-probe (SP) tests to measure permeability and in situ pore pressure and two dual-packer (DP) tests to measure minimum principal stress. Permeabilities defined from the SP tests range from 6.53 × 10-17 to 4.23 × 10-14 m2. Pore fluid pressures are near hydrostatic throughout the section despite rapid sedimentation. This is consistent with the measured hydraulic diffusivity of the sediments and suggests that the forearc basin should not trap overpressures within the upper plate of the subduction zone. Minimum principal stresses are consistently lower than the vertical stress. We estimate the maximum horizontal stress from wellbore failures at the leak-off test and shallow MDT DP test depths. The results indicate a normal or strike-slip stress regime, consistent with the observation of abundant active normal faults in the seaward-most part of the basin, and a general decrease in fault activity in the vicinity of Site C0009.

Central blood pressure in children and adolescents: non-invasive development and testing of novel transfer functions.

PubMed

Cai, T Y; Qasem, A; Ayer, J G; Butlin, M; O'Meagher, S; Melki, C; Marks, G B; Avolio, A; Celermajer, D S; Skilton, M R

2017-12-01

Central blood pressure can be estimated from peripheral pulses in adults using generalised transfer functions (TF). We sought to create and test age-specific non-invasively developed TFs in children, with comparison to a pre-existing adult TF. We studied healthy children from two sites at two time points, 8 and 14 years of age, split by site into development and validation groups. Radial and carotid pressure waveforms were obtained by applanation tonometry. Central systolic pressure was derived from carotid waveforms calibrated to brachial mean and diastolic pressures. Age-specific TFs created in the development groups (n=50) were tested in the validation groups aged 8 (n=137) and 14 years (n=85). At 8 years of age, the age-specific TF estimated 82, 99 and 100% of central systolic pressure values within 5, 10 and 15 mm Hg of their measured values, respectively. This TF overestimated central systolic pressure by 2.2 (s.d. 3.7) mm Hg, compared to being underestimated by 5.6 (s.d. 3.9) mm Hg with the adult TF. At 14 years of age, the age-specific TF estimated 60, 87 and 95% of values within 5, 10 and 15 mm Hg of their measured values, respectively. This TF underestimated central systolic pressure by 0.5 (s.d. 6.7) mm Hg, while the adult TF underestimated it by 6.8 (s.d. 6.0) mm Hg. In conclusion, age-specific TFs more accurately predict central systolic pressure measured at the carotid artery in children than an existing adult TF.

Validation of the pulse decomposition analysis algorithm using central arterial blood pressure

PubMed Central

2014-01-01

Background There is a significant need for continuous noninvasive blood pressure (cNIBP) monitoring, especially for anesthetized surgery and ICU recovery. cNIBP systems could lower costs and expand the use of continuous blood pressure monitoring, lowering risk and improving outcomes. The test system examined here is the CareTaker® and a pulse contour analysis algorithm, Pulse Decomposition Analysis (PDA). PDA’s premise is that the peripheral arterial pressure pulse is a superposition of five individual component pressure pulses that are due to the left ventricular ejection and reflections and re-reflections from only two reflection sites within the central arteries. The hypothesis examined here is that the model’s principal parameters P2P1 and T13 can be correlated with, respectively, systolic and pulse pressures. Methods Central arterial blood pressures of patients (38 m/25 f, mean age: 62.7 y, SD: 11.5 y, mean height: 172.3 cm, SD: 9.7 cm, mean weight: 86.8 kg, SD: 20.1 kg) undergoing cardiac catheterization were monitored using central line catheters while the PDA parameters were extracted from the arterial pulse signal obtained non-invasively using CareTaker system. Results Qualitative validation of the model was achieved with the direct observation of the five component pressure pulses in the central arteries using central line catheters. Statistically significant correlations between P2P1 and systole and T13 and pulse pressure were established (systole: R square: 0.92 (p < 0.0001), diastole: R square: 0.78 (p < 0.0001). Bland-Altman comparisons between blood pressures obtained through the conversion of PDA parameters to blood pressures of non-invasively obtained pulse signatures with catheter-obtained blood pressures fell within the trend guidelines of the Association for the Advancement of Medical Instrumentation SP-10 standard (standard deviation: 8 mmHg(systole: 5.87 mmHg, diastole: 5.69 mmHg)). Conclusions The results indicate that arterial blood pressure can be accurately measured and tracked noninvasively and continuously using the CareTaker system and the PDA algorithm. The results further support the physical model that all of the features of the pressure pulse envelope, whether in the central arteries or in the arterial periphery, can be explained by the interaction of the left ventricular ejection pressure pulse with two centrally located reflection sites. PMID:25005686

Arterial Pulse Pressure and Its Association With Reduced Stroke Volume During Progressive Central Hypovolemia

DTIC Science & Technology

2006-09-01

NM, Joyner MJ. Influence of increased central venous pressure on baroreflex control of sympathetic activity in humans. Am J Physiol Heart Circ Physiol...Arterial Pulse Pressure and Its Association With Reduced Stroke Volume During Progressive Central Hypovolemia Victor A. Convertino, PhD, William H...reduction of SV and change in MSNA during graded central hypovolemia in humans. Methods: After a 12-minute baseline data collection period, 13 men were

The Toxicity of Inhaled Sulphur Mustard

DTIC Science & Technology

2012-03-01

Pulse oximetry Mean arterial pressure Central venous pressure Blood Chemistry (arterial and venous ) pH pO2 pCO2 Sodium Potassium Calcium...Cardiovascular Parameters − CFI – Cardiac Function Index − CO – Cardiac Output − CvO2 – Mixed Venous Oxygenation − CVP – Central Venous Pressure...Data are expressed as mean ± SEM. Changes in central venous pressure following exposure to HD: HD controls () and HD + NAC (). Data are

Reliability of oscillometric central hemodynamic responses to an orthostatic challenge.

PubMed

Stoner, Lee; Bonner, Chantel; Credeur, Daniel; Lambrick, Danielle; Faulkner, James; Wadsworth, Daniel; Williams, Michelle A

2015-08-01

Monitoring central hemodynamic responses to an orthostatic challenge may provide important insight into autonomic nervous system function. Oscillometric pulse wave analysis devices have recently emerged, presenting clinically viable options for investigating central hemodynamic properties. The purpose of the current study was to determine whether oscillometric pulse wave analysis can be used to reliably (between-day) assess central blood pressure and central pressure augmentation (augmentation index) responses to a 5 min orthostatic challenge (modified tilt-table). Twenty healthy adults (26.4 y (SD 5.2), 55% F, 24.7 kg/m(2) (SD 3.8)) were tested on 3 different mornings in the fasted state, separated by a maximum of 7 days. Central hemodynamic variables were assessed on the left arm using an oscillometric device. Repeated measures analysis of variance indicated a significant main effect of the modified tilt-table for all central hemodynamic variables (P < 0.001). In response to the tilt, central diastolic pressure increased by 4.5 mmHg (CI: 2.6, 6.4), central systolic blood pressure increased by 2.3 (CI: 4.4, 0.16) mmHg, and augmentation index decreased by an absolute - 5.3%, (CI: -2.7, -7.9%). The intra-class correlation coefficient values for central diastolic pressure (0.83-0.86), central systolic blood pressure (0.80-0.87) and AIx (0.79-0.82) were above the 0.75 criterion in both the supine and tilted positions, indicating excellent between-day reliability. Central hemodynamic responses to an orthostatic challenge can be assessed with acceptable between-day reliability using oscillometric pulse wave analysis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Measurement of Capillary Radius and Contact Angle within Porous Media.

PubMed

Ravi, Saitej; Dharmarajan, Ramanathan; Moghaddam, Saeed

2015-12-01

The pore radius (i.e., capillary radius) and contact angle determine the capillary pressure generated in a porous medium. The most common method to determine these two parameters is through measurement of the capillary pressure generated by a reference liquid (i.e., a liquid with near-zero contact angle) and a test liquid. The rate of rise technique, commonly used to determine the capillary pressure, results in significant uncertainties. In this study, we utilize a recently developed technique for independently measuring the capillary pressure and permeability to determine the equivalent minimum capillary radii and contact angle of water within micropillar wick structures. In this method, the experimentally measured dryout threshold of a wick structure at different wicking lengths is fit to Darcy's law to extract the maximum capillary pressure generated by the test liquid. The equivalent minimum capillary radii of different wick geometries are determined by measuring the maximum capillary pressures generated using n-hexane as the working fluid. It is found that the equivalent minimum capillary radius is dependent on the diameter of pillars and the spacing between pillars. The equivalent capillary radii of micropillar wicks determined using the new method are found to be up to 7 times greater than the current geometry-based first-order estimates. The contact angle subtended by water at the walls of the micropillars is determined by measuring the capillary pressure generated by water within the arrays and the measured capillary radii for the different geometries. This mean contact angle of water is determined to be 54.7°.

Influence of geomagnetic activity and atmospheric pressure on human arterial pressure during the solar cycle 24

NASA Astrophysics Data System (ADS)

Azcárate, T.; Mendoza, B.; Levi, J. R.

2016-11-01

We performed a study of the systolic (SBP) and diastolic (DBP) arterial blood pressure behavior under natural variables such as the atmospheric pressure (AtmP) and the horizontal geomagnetic field component (H). We worked with a sample of 304 healthy normotense volunteers, 152 men and 152 women, with ages between 18 and 84 years in Mexico City during the period 2008-2014, corresponding to the minimum, ascending and maximum phases of the solar cycle 24. The data was divided by gender, age and day/night cycle. We studied the time series using three methods: Correlations, bivariate and superposed epochs (within a window of three days around the day of occurrence of a geomagnetic storm) analysis, between the SBP and DBP and the natural variables (AtmP and H). The correlation analysis indicated correlation between the SBP and DBP and AtmP and H, being the largest during the night. Furthermore, the correlation and bivariate analysis showed that the largest correlations are between the SBP and DBP and the AtmP. The superposed epoch analysis found that the largest number of significant SBP and DBP changes occurred for women. Finally, the blood pressure changes are larger during the solar minimum and ascending solar cycle phases than during the solar maximum; the storms of the minimum were more intense than those of the maximum and this could be the reason of behavior of the blood pressure changes along the solar cycle.

Quantification of peripheral and central blood pressure variability using a time-frequency method.

PubMed

Kouchaki, Z; Butlin, M; Qasem, A; Avolio, A P

2016-08-01

Systolic blood pressure variability (BPV) is associated with cardiovascular events. As the beat-to-beat variation of blood pressure is due to interaction of several cardiovascular control systems operating with different response times, assessment of BPV by spectral analysis using the continuous measurement of arterial pressure in the finger is used to differentiate the contribution of these systems in regulating blood pressure. However, as baroreceptors are centrally located, this study considered applying a continuous aortic pressure signal estimated noninvasively from finger pressure for assessment of systolic BPV by a time-frequency method using Short Time Fourier Transform (STFT). The average ratio of low frequency and high frequency power band (LF PB /HF PB ) was computed by time-frequency decomposition of peripheral systolic pressure (pSBP) and derived central aortic systolic blood pressure (cSBP) in 30 healthy subjects (25-62 years) as a marker of balance between cardiovascular control systems contributing in low and high frequency blood pressure variability. The results showed that the BPV assessed from finger pressure (pBPV) overestimated the BPV values compared to that assessed from central aortic pressure (cBPV) for identical cardiac cycles (P<;0.001), with the overestimation being greater at higher power.

Best Clinical Practices for the Sleep Center Adjustment of Noninvasive Positive Pressure Ventilation (NPPV) in Stable Chronic Alveolar Hypoventilation Syndromes

PubMed Central

2010-01-01

Summary: Noninvasive positive pressure ventilation (NPPV) devices are used during sleep to treat patients with diurnal chronic alveolar hypoventilation (CAH). Bilevel positive airway pressure (BPAP) using a mask interface is the most commonly used method to provide ventilatory support in these patients. BPAP devices deliver separately adjustable inspiratory positive airway pressure (IPAP) and expiratory positive airway pressure (EPAP). The IPAP and EPAP levels are adjusted to maintain upper airway patency, and the pressure support (PS = IPAP-EPAP) augments ventilation. NPPV devices can be used in the spontaneous mode (the patient cycles the device from EPAP to IPAP), the spontaneous timed (ST) mode (a backup rate is available to deliver IPAP for the set inspiratory time if the patient does not trigger an IPAP/EPAP cycle within a set time window), and the timed (T) mode (inspiratory time and respiratory rate are fixed). During NPPV titration with polysomnography (PSG), the pressure settings, backup rate, and inspiratory time (if applicable) are adjusted to maintain upper airway patency and support ventilation. However, there are no widely available guidelines for the titration of NPPV in the sleep center. A NPPV Titration Task Force of the American Academy of Sleep Medicine reviewed the available literature and developed recommendations based on consensus and published evidence when available. The major recommendations derived by this consensus process are as follows: General Recommendations:The indications, goals of treatment, and side effects of NPPV treatment should be discussed in detail with the patient prior to the NPPV titration study.Careful mask fitting and a period of acclimatization to low pressure prior to the titration should be included as part of the NPPV protocol.NPPV titration with PSG is the recommended method to determine an effective level of nocturnal ventilatory support in patients with CAH. In circumstances in which NPPV treatment is initiated and adjusted empirically in the outpatient setting based on clinical judgment, a PSG should be utilized if possible to confirm that the final NPPV settings are effective or to make adjustments as necessary.NPPV treatment goals should be individualized but typically include prevention of worsening of hypoventilation during sleep, improvement in sleep quality, relief of nocturnal dyspnea, and providing respiratory muscle rest.When OSA coexists with CAH, pressure settings for treatment of OSA may be determined during attended NPPV titration PSG following AASM Clinical Guidelines for the Manual Titration of Positive Airway Pressure in Patients with Obstructive Sleep Apnea.Attended NPPV titration with PSG is the recommended method to identify optimal treatment pressure settings for patients with the obesity hypoventilation syndrome (OHS), CAH due to restrictive chest wall disease (RTCD), and acquired or central CAH syndromes in whom NPPV treatment is indicated.Attended NPPV titration with PSG allows definitive identification of an adequate level of ventilatory support for patients with neuromuscular disease (NMD) in whom NPPV treatment is planned. Recommendations for NPPV Titration Equipment:The NPPV device used for titration should have the capability of operating in the spontaneous, spontaneous timed, and timed mode.The airflow, tidal volume, leak, and delivered pressure signals from the NPPV device should be monitored and recorded if possible. The airflow signal should be used to detect apnea and hypopnea, while the tidal volume signal and respiratory rate are used to assess ventilation.Transcutaneous or end-tidal PCO2 may be used to adjust NPPV settings if adequately calibrated and ideally validated with arterial blood gas testing.An adequate assortment of masks (nasal, oral, and oronasal) in both adult and pediatric sizes (if children are being titrated), a source of supplemental oxygen, and heated humidification should be available. Recommendations for Limits of IPAP, EPAP, and PS Settings:The recommended minimum starting IPAP and EPAP should be 8 cm H2O and 4 cm H2O, respectively.The recommended maximum IPAP should be 30 cm H2O for patients ≥ 12 years and 20 cm H2O for patients < 12 years.The recommended minimum and maximum levels of PS are 4 cm H2O and 20 cm H2O, respectively.The minimum and maximum incremental changes in PS should be 1 and 2 cm H2O, respectively. Recommendations for Adjustment of IPAP, EPAP, and PS:IPAP and/or EPAP should be increased as described in AASM Clinical Guidelines for the Manual Titration of Positive Airway Pressure in Patients with Obstructive Sleep Apnea until the following obstructive respiratory events are eliminated (no specific order): apneas, hypopneas, respiratory effort-related arousals, and snoring.The pressure support (PS) should be increased every 5 minutes if the tidal volume is low (< 6 to 8 mL/kg)The PS should be increased if the arterial PCO2 remains 10 mm Hg or more above the PCO2 goal at the current settings for 10 minutes or more. An acceptable goal for PCO2 is a value less than or equal to the awake PCO2.The PS may be increased if respiratory muscle rest has not been achieved by NPPV treatment at the current settings for 10 minutes of more.The PS may be increased if the SpO2 remains below 90% for 5 minutes or more and tidal volume is low (< 6 to 8 mL/kg). Recommendations for Use and Adjustment of the Backup Rate/Respiratory Rate:A backup rate (i.e., ST mode) should be used in all patients with central hypoventilation, those with a significant number of central apneas or an inappropriately low respiratory rate, and those who unreliably trigger IPAP/EPAP cycles due to muscle weakness.The ST mode may be used if adequate ventilation or adequate respiratory muscle rest is not achieved with the maximum (or maximum tolerated) PS in the spontaneous mode.The starting backup rate should be equal to or slightly less than the spontaneous sleeping respiratory rate (minimum of 10 bpm).The backup rate should be increased in 1 to 2 bpm increments every 10 minutes if the desired goal of the backup rate has not been attained.The IPAP time (inspiratory time) should be set based on the respiratory rate to provide an inspiratory time (IPAP time) between 30% and 40% of the cycle time (60/respiratory rate in breaths per minute).If the spontaneous timed mode is not successful at meeting titration goals then the timed mode can be tried. Recommendations Concerning Supplemental Oxygen:Supplemental oxygen may be added in patients with an awake SpO2 < 88% or when the PS and respiratory rate have been optimized but the SpO2 remains < 90% for 5 minutes or more.The minimum starting supplemental oxygen rate should be 1 L/minute and increased in increments of 1 L/minute about every 5 minutes until an adequate SpO2 is attained (> 90%). Recommendations to Improve Patient Comfort and Patient-NPPV Device Synchrony:If the patient awakens and complains that the IPAP and/or EPAP is too high, pressure should be lowered to a level comfortable enough to allow return to sleep.NPPV device parameters (when available) such as pressure relief, rise time, maximum and minimum IPAP durations should be adjusted for patient comfort and to optimize synchrony between the patient and the NPPV device.During the NPPV titration mask refit, adjustment, or change in mask type should be performed whenever any significant unintentional leak is observed or the patient complains of mask discomfort. If mouth leak is present and is causing significant symptoms (e.g., arousals) use of an oronasal mask or chin strap may be tried. Heated humidification should be added if the patient complains of dryness or significant nasal congestion. Recommendations for Follow-Up:Close follow-up after initiation of NPPV by appropriately trained health care providers is indicated to establish effective utilization patterns, remediate side effects, and assess measures of ventilation and oxygenation to determine if adjustment to NPPV is indicated. Citation: Berry RB; Chediak A; Brown LK; Finder J; Gozal D; Iber C; Kushida CA; Morgenthaler T; Rowley JA; Davidson-Ward SL. Best clinical practices for the sleep center adjustment of noninvasive positive pressure ventilation (NPPV) in stable chronic alveolar hypoventilation syndromes. J Clin Sleep Med 2010;6(5):497-509. PMID:20957853

Estimating Fluctuating Pressures From Distorted Measurements

NASA Technical Reports Server (NTRS)

Whitmore, Stephen A.; Leondes, Cornelius T.

1994-01-01

Two algorithms extract estimates of time-dependent input (upstream) pressures from outputs of pressure sensors located at downstream ends of pneumatic tubes. Effect deconvolutions that account for distoring effects of tube upon pressure signal. Distortion of pressure measurements by pneumatic tubes also discussed in "Distortion of Pressure Signals in Pneumatic Tubes," (ARC-12868). Varying input pressure estimated from measured time-varying output pressure by one of two deconvolution algorithms that take account of measurement noise. Algorithms based on minimum-covariance (Kalman filtering) theory.

49 CFR 232.103 - General requirements for all train brake systems.

Code of Federal Regulations, 2013 CFR

2013-10-01

... the air compressor governor starting or loading pressure. (l) Except as otherwise provided in this... brake pipe air pressure: Road Service 90 Switch Service 60 (2) Minimum differential between brake pipe and main reservoir air pressures, with brake valve in running position 15 (3) Safety valve for...

49 CFR 232.103 - General requirements for all train brake systems.

Code of Federal Regulations, 2012 CFR

2012-10-01

... the air compressor governor starting or loading pressure. (l) Except as otherwise provided in this... brake pipe air pressure: Road Service 90 Switch Service 60 (2) Minimum differential between brake pipe and main reservoir air pressures, with brake valve in running position 15 (3) Safety valve for...

[Ophthalmodynamometry in the diagnostics of Grave's ophthalmopathy].

PubMed

Harder, B; Jonas, J B

2007-11-01

Since endocrine orbitopathy is characterised by exophthalmos and increased orbital tissue pressure which may lead to a compression of and damage to the optic nerve, it was the purpose of this study to evaluate whether the increased orbital tissue pressure in endocrine orbitopathy is associated with an elevated central retinal vein pressure as estimated by ophthalmodynamometry, and whether the central retinal vein pressure changes in the course of the disease. The prospective clinical study included 7 patients (13 eyes) with endocrine orbitopathy. They were screened for the prevalence of a spontaneous pulsation of the central retinal vein. In case of a missing spontaneous pulse, the collapse pressure of the central retinal vein was estimated by a modified ophthalmodynamometry using a corneal contact lens associated ophthalmodynamometric device. A group of 122 patients (156 eyes) without orbital or retinal diseases served as control group. The frequency of a spontaneous pulse of the central retinal vein was significantly lower in the study group (1/13 or 8%) than in the control group (121/156 or 78% p<0.001; odds ratio: 41.5). The central retinal vein collapse pressure as determined by ophthalmodynamometry was significantly higher in the study group (22.7+/-19.5 arbitrary units) than in the control group (4.7+/-12.8 arbitrary units) (p=0.002). For one patient with 7 examinations during a follow-up of 16 months, the central retinal vein pressure increased from 17 arbitrary units to 56 units, and decreased to 14 to 19 arbitrary units after initiation of a systemic therapy and regression of the exophthalmos. Three years later a spontaneous pulsation of the central retinal vein was detectable. Ophthalmodynamometry may be a useful examination for the indirect assessment of the orbital tissue pressure in patients with endocrine orbitopathy.

The Toxicity of Inhaled Sulphur Mustard

DTIC Science & Technology

2012-10-01

Index − CO – Cardiac Output − CvO2 – Mixed Venous Oxygenation − CVP – Central Venous Pressure − DO2 – Oxygen Delivery − dpMax – Maximum...in central venous pressure following exposure to HD: HD controls () and HD + NAC (). Data are expressed as mean ± SEM. UK UNCLASSIFIED Page 64 of...Respiratory rate (RR) Heart rate (HR) Expired CO2 Pulse oximetry Mean arterial pressure Central venous pressure Blood Chemistry (arterial and

Dynamic fracture toughness of ASME SA508 Class 2a ASME SA533 grade A Class 2 base and heat affected zone material and applicable weld metals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Logsdon, W.A.; Begley, J.A.; Gottshall, C.L.

1978-03-01

The ASME Boiler and Pressure Vessel Code, Section III, Article G-2000, requires that dynamic fracture toughness data be developed for materials with specified minimum yield strengths greater than 50 ksi to provide verification and utilization of the ASME specified minimum reference toughness K/sub IR/ curve. In order to qualify ASME SA508 Class 2a and ASME SA533 Grade A Class 2 pressure vessel steels (minimum yield strengths equal 65 kip/in./sup 2/ and 70 kip/in./sup 2/, respectively) per this requirement, dynamic fracture toughness tests were performed on these materials. All dynamic fracture toughness values of SA508 Class 2a base and HAZ material,more » SA533 Grade A Class 2 base and HAZ material, and applicable weld metals exceeded the ASME specified minimum reference toughness K/sub IR/ curve.« less

Are long-term psychiatric patients causing more crisis consultations outside office hours in mental health care?

PubMed

Dekker, J; Theunissen, J; Van, R; Kikkert, M; van der Post, L; Zoeteman, J; Peen, J

2013-09-01

As well as an improvement in community services, the de-institutionalization of patients receiving long-term psychiatric care can lead to marginally staffed mental health services, more homelessness, rising admission rates and more people in prison cells. It is assumed that an imbalance between community and hospital care for chronic patients puts pressure on crisis services. In this study, the central question is whether patients receiving long-term psychiatric care in Amsterdam do indeed put pressure on the city's emergency mental health services. We compare the pressure exerted by this group with the pressure resulting from the use of these services by all registered patients. Data were taken from the client registration systems of three mental health organizations in Amsterdam in the period from 2000 to 2004. Inclusion criteria for long-term psychiatric patients were age above 19 years and uninterrupted receipt of mental health care for a minimum of two successive years. Annually, 6%-8% of all non-long-term patients experienced a crisis outside office hours in the period under investigation; this was 4%-6% for long-term patients. The non-long-term patients accounted for 83% of crisis contacts outside office hours over the entire study period, with long-term patients accounting for 17%. The assumption that crises are more prevalent in long-term patients in the community seems to be an example of stigmatization rather than an observation based on fact.

Simulation of hydrodynamics, temperature, and dissolved oxygen in Table Rock Lake, Missouri, 1996-1997

USGS Publications Warehouse

Green, W. Reed; Galloway, Joel M.; Richards, Joseph M.; Wesolowski, Edwin A.

2003-01-01

Outflow from Table Rock Lake and other White River reservoirs support a cold-water trout fishery of substantial economic yield in south-central Missouri and north-central Arkansas. The Missouri Department of Conservation has requested an increase in existing minimum flows through the Table Rock Lake Dam from the U.S. Army Corps of Engineers to increase the quality of fishable waters downstream in Lake Taneycomo. Information is needed to assess the effect of increased minimum flows on temperature and dissolved- oxygen concentrations of reservoir water and the outflow. A two-dimensional, laterally averaged, hydrodynamic, temperature, and dissolved-oxygen model, CE-QUAL-W2, was developed and calibrated for Table Rock Lake, located in Missouri, north of the Arkansas-Missouri State line. The model simulates water-surface elevation, heat transport, and dissolved-oxygen dynamics. The model was developed to assess the effects of proposed increases in minimum flow from about 4.4 cubic meters per second (the existing minimum flow) to 11.3 cubic meters per second (the increased minimum flow). Simulations included assessing the effect of (1) increased minimum flows and (2) increased minimum flows with increased water-surface elevations in Table Rock Lake, on outflow temperatures and dissolved-oxygen concentrations. In both minimum flow scenarios, water temperature appeared to stay the same or increase slightly (less than 0.37 ?C) and dissolved oxygen appeared to decrease slightly (less than 0.78 mg/L) in the outflow during the thermal stratification season. However, differences between the minimum flow scenarios for water temperature and dissolved- oxygen concentration and the calibrated model were similar to the differences between measured and simulated water-column profile values.

The Diurnal Profile of Central Hemodynamics in a General Uruguayan Population.

PubMed

Boggia, José; Luzardo, Leonella; Lujambio, Inés; Sottolano, Mariana; Robaina, Sebastián; Thijs, Lutgarde; Olascoaga, Alicia; Noboa, Oscar; Struijker-Boudier, Harry A; Safar, Michel E; Staessen, Jan A

2016-06-01

No previous population study assessed the diurnal profile of central arterial properties. In 167 participants (mean age, 56.1 years; 63.5% women), randomly recruited in Montevideo, Uruguay, we used the oscillometric Mobil-O-Graph 24-h PWA monitor to measure peripheral and central systolic (SBP), diastolic (DBP), and pulse (PP) pressures and central hemodynamics standardized to a heart rate of 75 bpm, including aortic pulse wave velocity, systolic augmentation (first/second peak × 100), and pressure amplification (peripheral PP/central PP). Over 24 hours, day and night, peripheral minus central differences in SBP/DBP and in PP averaged 12.2/-1.1, 14.0/-0.7, and 9.7/0.2mm Hg and 12.6, 14.7, and 9.5mm Hg, respectively (P < 0.001 except for nighttime DBP (P = 0.38)). The central-to-peripheral ratios of SBP, DBP, and PP were 0.89, 1.00, and 0.70 unadjusted, but after accounting for anthropometric characteristics decreased to 0.74, 0.97, and 0.63, respectively, with strong influence of height for SBP and DBP and of sex for PP. From day (10-20h) to nighttime (0-6h), peripheral (-10.4/-10.5 mm Hg) and central (-6.0/-11.3mm Hg) SBP/DBP, pulse wave velocity (-0.7 m/s) and pressure amplification (-0.05) decreased (P < 0.001), whereas central PP (+5.3mm Hg) and systolic augmentation (+2.3%) increased (P < 0.001). The diurnal rhythm of central pressure runs in parallel with that of peripheral pressure, but the nocturnal fall in SBP is smaller centrally than peripherally. pulse wave velocity, systolic augmentation, and pressure amplification loop through the day with high pulse wave velocity and pressure amplification but low systolic augmentation in the evening and opposite trends in the morning. © American Journal of Hypertension, Ltd 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Relations of Central Hemodynamics and Aortic Stiffness with Left Ventricular Structure and Function: The Framingham Heart Study.

PubMed

Kaess, Bernhard M; Rong, Jian; Larson, Martin G; Hamburg, Naomi M; Vita, Joseph A; Cheng, Susan; Aragam, Jayashree; Levy, Daniel; Benjamin, Emelia J; Vasan, Ramachandran S; Mitchell, Gary F

2016-03-25

The differing relations of steady and pulsatile components of central hemodynamics and aortic stiffness with cardiac dimensions and function have not been fully elucidated. Central hemodynamics and carotid-femoral pulse wave velocity (CFPWV, a measure of aortic stiffness) were measured by arterial tonometry in 5799 participants of the Framingham Heart Study (mean age 51 years, 54% women) and related to echocardiographic left ventricular (LV) dimensions and systolic and diastolic function using multivariable-adjusted partial Pearson correlations. Mean arterial pressure (MAP, steady component of central blood pressure) was associated positively with LV wall thickness (r=0.168; P<0.0001) but showed only a weak direct association with LV diastolic dimension (r=0.035, P=0.006). Central pulse pressure (pulsatile component of central blood pressure) showed a direct correlation with both LV diastolic dimension and LV wall thickness (r=0.08 and 0.044, both P<0.0001 in multivariable models that included MAP). CFPWV was not associated with LV structure (all P≥0.27) in MAP-adjusted models). Both MAP and CFPWV were associated inversely with LV diastolic function (E'; r=-0.140 and -0.153, respectively; both P<0.0001), and these associations persisted after additional adjustment for LV mass and central pulse pressure (r=-0.142 and -0.108, both P<0.0001). MAP and CFPWV were not associated with LV fractional shortening (P≥0.10), whereas central pulse pressure was positively related (r=0.064, P<0.0001). Pulsatile and steady components of central pressure are conjointly yet variably related to LV structure. CFPWV is related to LV diastolic function but not to systolic function. Additional studies are warranted to confirm these observations. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

42 CFR 84.201 - Head harnesses; minimum requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... of pressure over the entire area in contact with the face. (2) Facepieces for single-use vinyl... adequate tension during use and an even distribution of pressure over the entire area in contact with the...

30 CFR 250.1003 - Installation, testing, and repair requirements for DOI pipelines.

Code of Federal Regulations, 2010 CFR

2010-07-01

.... (a)(1) Pipelines greater than 8-5/8 inches in diameter and installed in water depths of less than 200... shall be pressure tested with water at a stabilized pressure of at least 1.25 times the MAOP for at... pressure tested with water or processed natural gas at a minimum stabilized pressure of at least 1.25 times...

Effects of antihypertensive drugs on central blood pressure in humans: a preliminary observation.

PubMed

Agnoletti, Davide; Zhang, Yi; Borghi, Claudio; Blacher, Jacques; Safar, Michel E

2013-08-01

Central blood pressure (BP) is considered a better predictor of cardiovascular events than brachial BP. Modifications of central, beyond brachial BP, can be assessed by pressure amplification, a potential new cardiovascular risk factor. Comparison between drugs' effect on central hemodynamics has been poorly studied. Our aim was to assess the hemodynamic effect of a 12-week treatment with amlodipine 5mg, or candesartan 8mg, or indapamide sustained-release 1.5mg, in comparison with placebo. We analyzed 145 out-patients with essential hypertension in primary prevention enrolled in the Natrilix SR Versus Candesartan and Amlodipine in the Reduction of Systolic Blood Pressure in Hypertensive Patients (X-CELLENT) study, a multicenter, randomized, double-blinded, placebo-controlled trial. Arterial stiffness, central BP, pressure amplification, and wave reflection were measured by applanation tonometry. Baseline characteristics of patients were homogeneous between groups. After treatment, we found that active drugs produced similar reduction of both central and peripheral BPs, with no significant interdrug differences (all P < 0.05; excluded peripheral pulse pressure, compared with placebo). Second, amlodipine (1.9% ± 15.3%), candesartan (3.0% ± 14.6%) and indapamide (4.1% ± 14.4%) all increased pulse pressure amplification, but only indapamide was statistically different from placebo (P = 0.02). Finally, no significant changes were observed on pulse wave velocity, heart rate, and augmentation index. The 3 antihypertensive drugs similarly reduced peripheral and central BP, as compared with placebo, but a significant increase in pulse pressure amplification was obtained only with indapamide, independently of arterial stiffness modifications. 3283161 by BIOPHARMA.

Burn Treatment: Annual Research Progress Report.

DTIC Science & Technology

1975-06-30

in addition to direct or indirect measurements of blood pressure. Central venous pressures are measured relatively frequently and, on occasion, a... Central venous pressure assessment. 5. EKG. 46 I 6. Sponge weighing. 7. Measurement of urine output during surgery. B. RESPIRATION 1. Counting of...start a central venous line prior to adminis- tration of vasopressors. The patient became progressively more hypo- tensive and bradycardiac, which

Stability of DIII-D high-performance, negative central shear discharges

NASA Astrophysics Data System (ADS)

Hanson, J. M.; Berkery, J. W.; Bialek, J.; Clement, M.; Ferron, J. R.; Garofalo, A. M.; Holcomb, C. T.; La Haye, R. J.; Lanctot, M. J.; Luce, T. C.; Navratil, G. A.; Olofsson, K. E. J.; Strait, E. J.; Turco, F.; Turnbull, A. D.

2017-05-01

Tokamak plasma experiments on the DIII-D device (Luxon et al 2005 Fusion Sci. Tech. 48 807) demonstrate high-performance, negative central shear (NCS) equilibria with enhanced stability when the minimum safety factor {{q}\\text{min}} exceeds 2, qualitatively confirming theoretical predictions of favorable stability in the NCS regime. The discharges exhibit good confinement with an L-mode enhancement factor H 89  =  2.5, and are ultimately limited by the ideal-wall external kink stability boundary as predicted by ideal MHD theory, as long as tearing mode (TM) locking events, resistive wall modes (RWMs), and internal kink modes are properly avoided or controlled. Although the discharges exhibit rotating TMs, locking events are avoided as long as a threshold minimum safety factor value {{q}\\text{min}}>2 is maintained. Fast timescale magnetic feedback control ameliorates RWM activity, expanding the stable operating space and allowing access to {β\\text{N}} values approaching the ideal-wall limit. Quickly growing and rotating instabilities consistent with internal kink mode dynamics are encountered when the ideal-wall limit is reached. The RWM events largely occur between the no- and ideal-wall pressure limits predicted by ideal MHD. However, evaluating kinetic contributions to the RWM dispersion relation results in a prediction of passive stability in this regime due to high plasma rotation. In addition, the ideal MHD stability analysis predicts that the ideal-wall limit can be further increased to {β\\text{N}}>4 by broadening the current profile. This path toward improved stability has the potential advantage of being compatible with the bootstrap-dominated equilibria envisioned for advanced tokamak (AT) fusion reactors.

Resting Sympathetic Baroreflex Sensitivity in Subjects with Low and High Tolerance to Central Hypovolemia Induced by Lower Body Negative Pressure

DTIC Science & Technology

2014-06-01

high tolerance to central hypovolemia induced by lower body negative pressure Carmen Hinojosa-Laborde1*, Kathy L. Ryan1, Caroline A. Rickards2 and...patients with high tolerance. Using lower body negative pressure (LBNP) as an experimental model to induce central hypovolemia, we have shown that...hypovolemia is associated with mainte- nance of adequate perfusion pressure (i.e., arterial blood pres- sure) to vital organs. Therefore, we hypothesize that

A Study to Determine the Evolution of Advances in Medical Technology Expected in the Next 25 Years and Possible Impacts on Coast Guard Operations and Support Programs.

DTIC Science & Technology

1980-05-01

abnormalities in pressure tracings of the systemic, the central venous or pulmonary arterial circulation. At some sites (especially the Latter-Day Saints...accurate measurement of central venous pressure has been by direct venous cannulation. However, a group of Swiss doctors has extended the principle of... venous stop flow pressure to develop a noninvasive method of measuring central venous pressure. The method consists of venous auscultation at the thoracic

Twenty-Four-Hour Central Pulse Pressure for Cardiovascular Events Prediction in a Low-Cardiovascular-Risk Population: Results From the Bordeaux Cohort.

PubMed

Cremer, Antoine; Boulestreau, Romain; Gaillard, Prune; Lainé, Marion; Papaioannou, Georgios; Gosse, Philippe

2018-02-23

Central blood pressure (BP) is a promising marker to identify subjects with higher cardiovascular risk than expected by traditional risk factors. Significant results have been obtained in populations with high cardiovascular risk, but little is known about low-cardiovascular-risk patients, although the differences between central and peripheral BP (amplification) are usually greater in this population. The study aim was to evaluate central BP over 24 hours for cardiovascular event prediction in hypertensive subjects with low cardiovascular risk. Peripheral and central BPs were recorded during clinical visits and over 24 hours in hypertensive patients with low cardiovascular risk (Systematic Coronary Risk Evaluation ≤5%). Our primary end point is the occurrence of a cardiovascular event during follow-up. To assess the potential interest in central pulse pressure over 24 hours, we performed Cox proportional hazard models analysis and comparison of area under the curves using the contrast test for peripheral and central BP. A cohort of 703 hypertensive subjects from Bordeaux were included. After the first 24 hours of BP measurement, the subjects were then followed up for an average of 112.5±70 months. We recorded 65 cardiovascular events during follow-up. Amplification was found to be significantly associated with cardiovascular events when added to peripheral 24-hour pulse pressure ( P =0.0259). The area under the curve of 24-hour central pulse pressure is significantly more important than area under the curve of office BP ( P =0.0296), and there is a trend of superiority with the area under the curve of peripheral 24-hour pulse pressure. Central pulse pressure over 24 hours improves the prediction of cardiovascular events for hypertensive patients with low cardiovascular risk compared to peripheral pulse pressure. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

INDEPENDENT SIGNALS FROM THE INFLUENCE OF INTERNAL MAGNETIC LAYERS ON THE FREQUENCIES OF SOLAR p-MODES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foullon, C.; Nakariakov, V. M.

2010-05-01

The discovery that p-mode frequencies of low degree do not follow changes of solar surface activity during the recent solar minimum offers the possibility of a new diagnostic signature of the responsible pressure perturbation in the wave guiding medium, potentially rich of information regarding the structure of the Sun and the cause of the unusually long solar minimum. Magnetic fields, as well as temperature changes, introduce equilibrium pressure deviations that modify the resonant frequencies of p-mode oscillations. Assuming the perturbation to be caused by a horizontal layer of magnetic field located in a plane-stratified model of the Sun, we compilemore » analytical frequency shifts and process them to allow direct comparison with observations. The effect of magnetism itself on the central p-mode frequencies can be neglected in comparison with the thermal effect of a perturbative layer buried in the solar interior. A parametric study shows that a layer as thin as 2100 km at subsurface depths is able to reproduce reported mean anomalous frequency shifts (not correlated with the surface activity), while a layer of size around 4200 km increasing by a small amount at depths near 0.08 R {sub sun} can explain individual low-degree shifts. It is also possible to obtain the mean shifts via the upward motion through depths near 0.03 R {sub sun} of a rising perturbative layer of thickness around 7000 km. Hence, the anomalous frequency shifts are best explained by thermal effects in the upper regions of the convection zone. The effects of latitudinal distribution are not treated here.« less

Multimodal pressure-flow method to assess dynamics of cerebral autoregulation in stroke and hypertension.

PubMed

Novak, Vera; Yang, Albert C C; Lepicovsky, Lukas; Goldberger, Ary L; Lipsitz, Lewis A; Peng, Chung-Kang

2004-10-25

This study evaluated the effects of stroke on regulation of cerebral blood flow in response to fluctuations in systemic blood pressure (BP). The autoregulatory dynamics are difficult to assess because of the nonstationarity and nonlinearity of the component signals. We studied 15 normotensive, 20 hypertensive and 15 minor stroke subjects (48.0 +/- 1.3 years). BP and blood flow velocities (BFV) from middle cerebral arteries (MCA) were measured during the Valsalva maneuver (VM) using transcranial Doppler ultrasound. A new technique, multimodal pressure-flow analysis (MMPF), was implemented to analyze these short, nonstationary signals. MMPF analysis decomposes complex BP and BFV signals into multiple empirical modes, representing their instantaneous frequency-amplitude modulation. The empirical mode corresponding to the VM BP profile was used to construct the continuous phase diagram and to identify the minimum and maximum values from the residual BP (BPR) and BFV (BFVR) signals. The BP-BFV phase shift was calculated as the difference between the phase corresponding to the BPR and BFVR minimum (maximum) values. BP-BFV phase shifts were significantly different between groups. In the normotensive group, the BFVR minimum and maximum preceded the BPR minimum and maximum, respectively, leading to large positive values of BP-BFV shifts. In the stroke and hypertensive groups, the resulting BP-BFV phase shift was significantly smaller compared to the normotensive group. A standard autoregulation index did not differentiate the groups. The MMPF method enables evaluation of autoregulatory dynamics based on instantaneous BP-BFV phase analysis. Regulation of BP-BFV dynamics is altered with hypertension and after stroke, rendering blood flow dependent on blood pressure.

Power Doppler of the urethra in continent or incontinent, pre- and postmenopausal women.

PubMed

Jármy-Di Bella, Z I; Girão, M J; Sartori, M F; Di Bella Júnior, V; Lederman, H M; Baracat, E C; Lima, G R

2000-06-01

Urethral pressure should exceed bladder pressure, both at rest and on stress, for urinary continence to occur. A decrease in urethral pressure is a major factor explaining the pathogenesis of urinary incontinence. A number of elements, such as smooth and striated periurethral muscles, and connective, vascular and elastic tissues, contribute to urethral pressure. The periurethral vessels are influenced by hormonal changes during the menstrual cycle, during pregnancy and postmenopause. We studied the periurethral vessels in 97 women, 57 of whom were incontinent and 40 continent, using power color Doppler velocimetry. The number of periurethral vessels, systolic peak, minimum diastolic values, pulsatility and resistance indexes, as well as systolic-diastolic ratio, were assessed. Statistically significant differences were found between incontinent women in the premenopausal period and those in the postmenopausal period, regarding the number of periurethral vessels, systolic peak, minimum diastolic values, pulsatility and resistance indexes.

Intercooler cooling-air weight flow and pressure drop for minimum drag loss

NASA Technical Reports Server (NTRS)

Reuter, J George; Valerino, Michael F

1944-01-01

An analysis has been made of the drag losses in airplane flight of cross-flow plate and tubular intercoolers to determine the cooling-air weight flow and pressure drop that give a minimum drag loss for any given cooling effectiveness and, thus, a maximum power-plant net gain due to charge-air cooling. The drag losses considered in this analysis are those due to (1) the extra drag imposed on the airplane by the weight of the intercooler, its duct, and its supports and (2) the drag sustained by the cooling air in flowing through the intercooler and its duct. The investigation covers a range of conditions of altitude, airspeed, lift-drag ratio, supercharger-pressure ratio, and supercharger adiabatic efficiency. The optimum values of cooling air pressure drop and weight flow ratio are tabulated. Curves are presented to illustrate the results of the analysis.

76 FR 9449 - National Emission Standards for Hazardous Air Pollutants: Gold Mine Ore Processing and Production...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-17

... chemistry, scrubber pressure drop, and scrubber inlet gas temperature hourly. The final rule does not... pressure) and inlet gas temperature to be based on the minimum flow rate (or line pressure) or maximum inlet gas temperature established during the initial performance test. It also includes two additional...

Oxygen Concentration Flammability Threshold Tests for the Constellation Program

NASA Technical Reports Server (NTRS)

Williams, James H.

2007-01-01

CEV atmosphere will likely change because craft will be used as LEO spacecraft, lunar spacecraft, orbital spacecraft. Possible O2 % increase and overall pressure decrease pressure vessel certs on spacecraft. Want 34% minimum threshold. Higher, better when atmosphere changes. WSTF suggests testing all materials/components to find flammability threshold, pressure and atmosphere.

Aerodynamics of a Transitioning Turbine Stator Over a Range of Reynolds Numbers

NASA Technical Reports Server (NTRS)

Boyle, R. J.; Lucci, B. L.; Verhoff, V. G.; Camperchioli, W. P.; La, H.

1998-01-01

Midspan aerodynamic measurements for a three vane-four passage linear turbine vane cascade are given. The vane axial chord was 4.45 cm. Surface pressures and loss coefficients were measured at exit Mach numbers of 0.3, 0.7, and 0.9. Reynolds number was varied by a factor of six at the two highest Mach numbers, and by a factor of ten at the lowest Mach number. Measurements were made with and without a turbulence grid. Inlet turbulence intensities were less than I% and greater than IO%. Length scales were also measured. Pressurized air fed the test section, and exited to a low pressure exhaust system. Maximum inlet pressure was two atmospheres. The minimum inlet pressure for an exit Mach number of 0.9 was one-third of an atmosphere, and at a Mach number of 0.3, the minimum pressure was half this value. The purpose of the test was to provide data for verification of turbine vane aerodynamic analyses, especially at low Reynolds numbers. Predictions obtained using a Navier-Stokes analysis with an algebraic turbulence model are also given.

Central Corneal Thickness and its Relationship to Intra-Ocular and Epidmiological Determinants.

PubMed

Tayyab, Ali; Masrur, Amena; Afzal, Farooq; Iqbal, Fyza; Naseem, Kamran

2016-06-01

To measure central corneal thickness in Pakistani population and determine its relationship to intra-ocular pressure, age, gender and ethnicity. Cross-sectional observation study. Pakistan Institute of Medical Sciences, Islamabad, Pakistan, between December 2013 and February 2015. The right eyes of 1000 cases (496 males and 504 females) were recruited for this study. Inclusion criteria were Pashtun or Punjabi ethnicity, intra-ocular pressure < 22 mmHg, gonioscopically open angles, cup-disk-ratio < 0.5, and age matched normal visual fields. Cases with prior ocular surgery, contact lens use, corneal pathologies, myopia or hypermetropia > ±3.0 diopters, astigmatism of > ±1.0 diopters were excluded. Central corneal thickness was measured using a TopCon non-contact specular microscope. Intra-ocular pressure was measured using Goldmann applanation tonometer. Frequency distribution, test of significance, and regression analysis was carried out using Statistical Package for Social Sciences version 20.0. Mean age was 47.31 ±11.78 years. Ethnic composition was 51.6% (n=516) Pashtun and 48.4% (n=484) Punjabi. The mean central corneal thickness was 503.96 (±12.47) µm, while the mean intra-ocular pressure was 15.61 (±2.68) mmHg. Regression analysis showed a significant association between central corneal thickness and intra-ocular pressure (p=0.00) and age (p=0.00). A±100 µchange in central corneal thickness was associated with change in IOPof ±3.30 mmHg, whereas central corneal thickness decreased by 0.12 µm per year. No significant association could be established between central corneal thickness and ethnicity (p=0.19). Central corneal thickness of the studied races was comparable to non-Caucasians which affects intra-ocular pressure measurements, and decreases with increasing age. No relationship was observed between central corneal thickness and ethnicity or gender.

Physiologic Pressure and Flow Changes During Parabolic Flight (Pilot Study)

NASA Technical Reports Server (NTRS)

Pantalos, George; Sharp, M. Keith; Mathias, John R.; Hargens, Alan R.; Watenpaugh, Donald E.; Buckey, Jay C.

1999-01-01

The objective of this study was to obtain measurement of cutaneous tissue perfusion central and peripheral venous pressure, and esophageal and abdominal pressure in human test subjects during parabolic flight. Hemodynamic data recorded during SLS-I and SLS-2 missions have resulted in the paradoxical finding of increased cardiac stroke volume in the presence of a decreased central venous pressure (CVP) following entry in weightlessness. The investigators have proposed that in the absence of gravity, acceleration-induced peripheral vascular compression is relieved, increasing peripheral vascular capacity and flow while reducing central and peripheral venous pressure, This pilot study seeks to measure blood pressure and flow in human test subjects during parabolic flight for different postures.

Correlations of catalytic combustor performance parameters

NASA Technical Reports Server (NTRS)

Bulzan, D. L.

1978-01-01

Correlations for combustion efficiency percentage drop and the minimum required adiabatic reaction temperature necessary to meet emissions goals of 13.6 g CO/kg fuel and 1.64 g HC/kg fuel are presented. Combustion efficiency was found to be a function of the cell density, cell circumference, reactor length, reference velocity, and adiabatic reaction temperature. The percentage pressure drop at an adiabatic reaction temperature of 1450 K was found to be proportional to the reference velocity to the 1.5 power and to the reactor length. It is inversely proportional to the pressure, cell hydraulic diameter, and fractional open area. The minimum required adiabatic reaction temperature was found to increase with reference velocity and decrease with cell circumference, cell density and reactor length. A catalyst factor was introduced into the correlations to account for differences between catalysts. Combustion efficiency, the percentage pressure drop, and the minimum required adiabatic reaction temperature were found to be a function of the catalyst factor. The data was from a 12 cm-diameter test rig with noble metal reactors using propane fuel at an inlet temperature of 800 K.

Hemodynamic Correlates of Abnormal Aortic Root Dimension in an Adult Population: The Strong Heart Study.

PubMed

de Simone, Giovanni; Roman, Mary J; De Marco, Marina; Bella, Jonathan N; Izzo, Raffaele; Lee, Elisa T; Devereux, Richard B

2015-09-28

We evaluated the relationship of aortic root dimension (ARD) with flow output and both peripheral and central blood pressure, using multivariable equations predicting ideal sex-specific ARD at a given age and body height. We measured echocardiographic diastolic ARD at the sinuses of Valsalva in 3160 adults (aged 42±16 years, 61% women) from the fourth examination of the Strong Heart Study who were free of prevalent coronary heart disease, and we compared measured data with the theoretical predicted value to calculate a z score. Central blood pressure was estimated by applanation tonometry of the radial artery in 2319 participants. ARD z scores were divided into tertiles representing small, normal, and large ARD. Participants with large ARD exhibited greater prevalence of central obesity and higher levels of inflammatory markers and lipids (0.05

Alternating versus synchronous ventilation of left and right lungs in piglets.

PubMed

Versprille, A; Hrachovina, V; Jansen, J R

1995-12-01

We tested whether alternating ventilation (AV) of each lung (i.e. with a phase difference of half a ventilatory cycle) would decrease central venous pressure and so increase cardiac output when compared with simultaneous ventilation (SV) of both lungs. If, during AV, the inflated lung expands partly via compression of the opposite lung, mean lung volume will be smaller during AV than SV. As a consequence, mean intrathoracic pressure (as cited in the literature), and therefore, central venous pressure will be smaller. The experiments were performed in seven anaesthetized and paralyzed piglets using a double-piston ventilator. Minute ventilation was the same during AV and SV. Starting at SV, we alternated three times between AV and SV for periods of 10 min. During AV, central venous pressure was decreased by 0.7 mmHg and cardiac output was increased by 10 +/- 4.4% (mean, +/-SD) compared with SV. AV also resulted in increased arterial pressure. During one-sided inflation with closed outlet of the opposite lung, a pressure rise occurred in the opposite lung, indicating compression. The higher cardiac output during AV than SV can be explained by the fact that central venous pressure is lower during AV. This lower central venous pressure is very probably due to the lower mean intrathoracic pressure caused by compression of the opposite lung during unilateral inflation.

42 CFR 84.152 - Breathing tube test; minimum requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

...: (i) Be employed on Type C supplied-air respirators of the demand and pressure-demand class; and (ii... SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Supplied-Air Respirators § 84.152 Breathing tube test; minimum requirements. (a)(1) Type A and Type B supplied-air...

24 CFR 200.926e - Supplemental information for use with the CABO One and Two Family Dwelling Code.

Code of Federal Regulations, 2014 CFR

2014-04-01

... shall be in accordance with section 7 of ASCE 7-88. (c) Wind pressures. The minimum Design Wind Pressures (net pressures) set forth below apply to areas designated as experiencing basic wind speeds up to and including 80 mph, as shown in ASCE 7-88, Figure 1, Basic Wind Speed Map. These pressures also...

24 CFR 200.926e - Supplemental information for use with the CABO One and Two Family Dwelling Code.

Code of Federal Regulations, 2013 CFR

2013-04-01

... shall be in accordance with section 7 of ASCE 7-88. (c) Wind pressures. The minimum Design Wind Pressures (net pressures) set forth below apply to areas designated as experiencing basic wind speeds up to and including 80 mph, as shown in ASCE 7-88, Figure 1, Basic Wind Speed Map. These pressures also...

24 CFR 200.926e - Supplemental information for use with the CABO One and Two Family Dwelling Code.

Code of Federal Regulations, 2012 CFR

2012-04-01

... shall be in accordance with section 7 of ASCE 7-88. (c) Wind pressures. The minimum Design Wind Pressures (net pressures) set forth below apply to areas designated as experiencing basic wind speeds up to and including 80 mph, as shown in ASCE 7-88, Figure 1, Basic Wind Speed Map. These pressures also...

24 CFR 200.926e - Supplemental information for use with the CABO One and Two Family Dwelling Code.

Code of Federal Regulations, 2010 CFR

2010-04-01

... shall be in accordance with section 7 of ASCE 7-88. (c) Wind pressures. The minimum Design Wind Pressures (net pressures) set forth below apply to areas designated as experiencing basic wind speeds up to and including 80 mph, as shown in ASCE 7-88, Figure 1, Basic Wind Speed Map. These pressures also...

24 CFR 200.926e - Supplemental information for use with the CABO One and Two Family Dwelling Code.

Code of Federal Regulations, 2011 CFR

2011-04-01

... shall be in accordance with section 7 of ASCE 7-88. (c) Wind pressures. The minimum Design Wind Pressures (net pressures) set forth below apply to areas designated as experiencing basic wind speeds up to and including 80 mph, as shown in ASCE 7-88, Figure 1, Basic Wind Speed Map. These pressures also...

Observations of shallow water marine ambient sound: the low frequency underwater soundscape of the central Oregon coast.

PubMed

Haxel, Joseph H; Dziak, Robert P; Matsumoto, Haru

2013-05-01

A year-long experiment (March 2010 to April 2011) measuring ambient sound at a shallow water site (50 m) on the central OR coast near the Port of Newport provides important baseline information for comparisons with future measurements associated with resource development along the inner continental shelf of the Pacific Northwest. Ambient levels in frequencies affected by surf-generated noise (f < 100 Hz) characterize the site as a high-energy end member within the spectrum of shallow water coastal areas influenced by breaking waves. Dominant sound sources include locally generated ship noise (66% of total hours contain local ship noise), breaking surf, wind induced wave breaking and baleen whale vocalizations. Additionally, an increase in spectral levels for frequencies ranging from 35 to 100 Hz is attributed to noise radiated from distant commercial ship commerce. One-second root mean square (rms) sound pressure level (SPLrms) estimates calculated across the 10-840 Hz frequency band for the entire year long deployment show minimum, mean, and maximum values of 84 dB, 101 dB, and 152 dB re 1 μPa.

High methane natural gas/air explosion characteristics in confined vessel.

PubMed

Tang, Chenglong; Zhang, Shuang; Si, Zhanbo; Huang, Zuohua; Zhang, Kongming; Jin, Zebing

2014-08-15

The explosion characteristics of high methane fraction natural gas were investigated in a constant volume combustion vessel at different initial conditions. Results show that with the increase of initial pressure, the peak explosion pressure, the maximum rate of pressure rise increase due to a higher amount (mass) of flammable mixture, which delivers an increased amount of heat. The increased total flame duration and flame development time result as a consequence of the higher amount of flammable mixture. With the increase of the initial temperature, the peak explosion pressures decrease, but the pressure increase during combustion is accelerated, which indicates a faster flame speed and heat release rate. The maximum value of the explosion pressure, the maximum rate of pressure rise, the minimum total combustion duration and the minimum flame development time is observed when the equivalence ratio of the mixture is 1.1. Additionally, for higher methane fraction natural gas, the explosion pressure and the maximum rate of pressure rise are slightly decreased, while the combustion duration is postponed. The combustion phasing is empirically correlated with the experimental parameters with good fitting performance. Furthermore, the addition of dilute gas significantly reduces the explosion pressure, the maximum rate of pressure rise and postpones the flame development and this flame retarding effect of carbon dioxide is stronger than that of nitrogen. Copyright © 2014 Elsevier B.V. All rights reserved.

40 CFR 65.84 - Operating requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

...-tight means that the pressure in a truck or railcar tank will not drop more than 750 pascals (0.11 pound per square inch) within 5 minutes after it is pressurized to a minimum of 4,500 pascals (0.65 pound...

Source mechanism analysis of central Aceh earthquake July 2, 2013 Mw 6.2 using moment tensor inversion with BMKG waveform data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prasetyo, Retno Agung, E-mail: prasetyo.agung@bmkg.go.id; Heryandoko, Nova; Afnimar

The source mechanism of earthquake on July 2, 2013 was investigated by using moment tensor inversion. The result also compared by the field observation. Five waveform data of BMKG’s seismic network used to estimate the mechanism of earthquake, namely ; KCSI, MLSI, LASI, TPTI and SNSI. Main shock data taken during 200 seconds and filtered by using Butterworth band pass method from 0.03 to 0.05 Hz of frequency. Moment tensor inversion method is applied based on the point source assumption. Furthermore, the Green function calculated using the extended reflectivity method which modified by Kohketsu. The inversion result showed a strike-slipmore » faulting, where the nodal plane strike/dip/rake (124/80.6/152.8) and minimum variance value 0.3285 at a depth of 6 km (centroid). It categorized as a shallow earthquake. Field observation indicated that the building orientated to the east. It can be related to the southwest of dip direction which has 152 degrees of slip. As conclusion, the Pressure (P) and Tension (T) axis described dominant compression is happen from the south which is caused by pressure of the Indo-Australian plate.« less

BOREAS AES READAC Surface Meteorological Data

NASA Technical Reports Server (NTRS)

Atkinson, G. Barrie; Funk, Barry; Hall, Forrest G. (Editor); Knapp, David E. (Editor)

2000-01-01

Canadian AES personnel collected and processed data related to surface atmospheric meteorological conditions over the BOREAS region. This data set contains 15-minute meteorological data from one READAC meteorology station in Hudson Bay, Saskatchewan. Parameters include day, time, type of report, sky condition, visibility, mean sea level pressure, temperature, dewpoint, wind, altimeter, opacity, minimum and maximum visibility, station pressure, minimum and maximum air temperature, a wind group, precipitation, and precipitation in the last hour. The data were collected non-continuously from 24-May-1994 to 20-Sep-1994. The data are provided in tabular ASCII files, and are classified as AFM-Staff data.

Phase behavior of metastable liquid silicon at negative pressure: Ab initio molecular dynamics

NASA Astrophysics Data System (ADS)

Zhao, G.; Yu, Y. J.; Yan, J. L.; Ding, M. C.; Zhao, X. G.; Wang, H. Y.

2016-04-01

Extensive first-principle molecular dynamics simulations are performed to study the phase behavior of metastable liquid Si at negative pressure. Our results show that the high-density liquid (HDL) and HDL-vapor spinodals indeed form a continuous reentrant curve and the liquid-liquid critical point seems to just coincide with its minimum. The line of density maxima also has a strong tendency to pass through this minimum. The phase behaviour of metastable liquid Si therefore tends to be a critical-point-free scenario rather than a second-critical-point one based on SW potential.

Effect of geometry on hydrodynamic film thickness

NASA Technical Reports Server (NTRS)

Brewe, D. E.; Hamrock, B. J.; Taylor, C. M.

1978-01-01

The influence of geometry on the isothermal hydrodynamic film separating two rigid solids was investigated. Pressure-viscosity effects were not considered. The minimum film thickness is derived for fully flooded conjunctions by using the Reynolds conditions. It was found that the minimum film thickness had the same speed, viscosity, and load dependence as Kapitza's classical solution. However, the incorporation of Reynolds boundary conditions resulted in an additional geometry effect. Solutions using the parabolic film approximation are compared with those using the exact expression for the film in the analysis. Contour plots are shown that indicate in detail the pressure developed between the solids.

Effect of geometry on hydrodynamic film thickness

NASA Technical Reports Server (NTRS)

Brewe, D. E.; Hamrock, B. J.; Taylor, C. M.

1978-01-01

The influence of geometry on the isothermal hydrodynamic film separating two rigid solids was investigated. Pressure-viscosity effects were not considered. The minimum film thickness is derived for fully flooded conjunctions by using the Reynolds boundary conditions. It was found that the minimum film thickness had the same speed, viscosity, and load dependence as Kapitza's classical solution. However, the incorporation of Reynolds boundary conditions resulted in an additional geometry effect. Solutions using the parabolic film approximation are compared with those using the exact expression for the film in the analysis. Contour plots are shown that indicate in detail the pressure developed between the solids.

The small-x gluon distribution in centrality biased pA and pp collisions

NASA Astrophysics Data System (ADS)

Dumitru, Adrian; Kapilevich, Gary; Skokov, Vladimir

2018-06-01

The nuclear modification factor RpA (pT) provides information on the small-x gluon distribution of a nucleus at hadron colliders. Several experiments have recently measured the nuclear modification factor not only in minimum bias but also for central pA collisions. In this paper we analyze the bias on the configurations of soft gluon fields introduced by a centrality selection via the number of hard particles. Such bias can be viewed as reweighting of configurations of small-x gluons. We find that the biased nuclear modification factor QpA (pT) for central collisions is above RpA (pT) for minimum bias events, and that it may redevelop a "Cronin peak" even at small x. The magnitude of the peak is predicted to increase approximately like 1 /A⊥ ν, ν ∼ 0.6 ± 0.1, if one is able to select more compact configurations of the projectile proton where its gluons occupy a smaller transverse area A⊥. We predict an enhanced Qpp (pT) - 1 ∼ 1 /(pT2) ν and a Cronin peak even for central pp collisions.

Cooling apparatus with a resilient heat conducting member

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chainer, Timothy J.; Parida, Pritish R.; Schultz, Mark D.

2016-06-14

A cooling structure including a thermally conducting central element having a channel formed therein, the channel being configured for flow of cooling fluid there through, a first pressure plate, and a first thermally conductive resilient member disposed between the thermally conducting central element and the first pressure plate, wherein the first pressure plate, the first thermally conductive resilient member, and the thermally conducting central element form a first heat transfer path.

A novel cell weighing method based on the minimum immobilization pressure for biological applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Qili; Institute of Robotics and Automatic Information System, Nankai University, Tianjin 300071; Shirinzadeh, Bijan

2015-07-28

A novel weighing method for cells with spherical and other regular shapes is proposed in this paper. In this method, the relationship between the cell mass and the minimum aspiration pressure to immobilize the cell (referred to as minimum immobilization pressure) is derived for the first time according to static theory. Based on this relationship, a robotic cell weighing process is established using a traditional micro-injection system. Experimental results on porcine oocytes demonstrate that the proposed method is able to weigh cells at an average speed of 16.3 s/cell and with a success rate of more than 90%. The derived cellmore » mass and density are in accordance with those reported in other published results. The experimental results also demonstrated that this method is able to detect less than 1% variation of the porcine oocyte mass quantitatively. It can be conducted by a pair of traditional micropipettes and a commercial pneumatic micro-injection system, and is expected to perform robotic operation on batch cells. At present, the minimum resolution of the proposed method for measuring the cell mass can be 1.25 × 10{sup −15 }kg. Above advantages make it very appropriate for quantifying the amount of the materials injected into or moved out of the cells in the biological applications, such as nuclear enucleations and embryo microinjections.« less

Seawater osmium isotope evidence for a middle Miocene flood basalt event in ferromanganese crust records

USGS Publications Warehouse

Klemm, V.; Frank, M.; Levasseur, S.; Halliday, A.N.; Hein, J.R.

2008-01-01

Three ferromanganese crusts from the northeast, northwest and central Atlantic were re-dated using osmium (Os) isotope stratigraphy and yield ages from middle Miocene to the present. The three Os isotope records do not show evidence for growth hiatuses. The reconstructed Os isotope-based growth rates for the sections older than 10??Ma are higher than those determined previously by the combined beryllium isotope (10Be/9Be) and cobalt (Co) constant-flux methods, which results in a decrease in the maximum age of each crust. This re-dating does not lead to significant changes to the interpretation of previously determined radiogenic isotope neodymium, lead (Nd, Pb) time series because the variability of these isotopes was very small in the records of the three crusts prior to 10??Ma. The Os isotope record of the central Atlantic crust shows a pronounced minimum during the middle Miocene between 15 and 12??Ma, similar to a minimum previously observed in two ferromanganese crusts from the central Pacific. For the other two Atlantic crusts, the Os isotope records and their calibration to the global seawater curve for the middle Miocene are either more uncertain or too short and thus do not allow for a reliable identification of an isotopic minimum. Similar to pronounced minima reported previously for the Cretaceous/Tertiary and Eocene/Oligocene boundaries, possible interpretations for the newly identified middle Miocene Os isotope minimum include changes in weathering intensity and/or a meteorite impact coinciding with the formation of the No??rdlinger Ries Crater. It is suggested that the eruption and weathering of the Columbia River flood basalts provided a significant amount of the unradiogenic Os required to produce the middle Miocene minimum. ?? 2008 Elsevier B.V.

Local amplification of storm surge by Super Typhoon Haiyan in Leyte Gulf.

PubMed

Mori, Nobuhito; Kato, Masaya; Kim, Sooyoul; Mase, Hajime; Shibutani, Yoko; Takemi, Tetsuya; Tsuboki, Kazuhisa; Yasuda, Tomohiro

2014-07-28

Typhoon Haiyan, which struck the Philippines in November 2013, was an extremely intense tropical cyclone that had a catastrophic impact. The minimum central pressure of Typhoon Haiyan was 895 hPa, making it the strongest typhoon to make landfall on a major island in the western North Pacific Ocean. The characteristics of Typhoon Haiyan and its related storm surge are estimated by numerical experiments using numerical weather prediction models and a storm surge model. Based on the analysis of best hindcast results, the storm surge level was 5-6 m and local amplification of water surface elevation due to seiche was found to be significant inside Leyte Gulf. The numerical experiments show the coherent structure of the storm surge profile due to the specific bathymetry of Leyte Gulf and the Philippines Trench as a major contributor to the disaster in Tacloban. The numerical results also indicated the sensitivity of storm surge forecast.

Optimal glottal configuration for ease of phonation.

PubMed

Lucero, J C

1998-06-01

Recent experimental studies have shown the existence of optimal values of the glottal width and convergence angle, at which the phonation threshold pressure is minimum. These results indicate the existence of an optimal glottal configuration for ease of phonation, not predicted by the previous theory. In this paper, the origin of the optimal configuration is investigated using a low dimensional mathematical model of the vocal fold. Two phenomena of glottal aerodynamics are examined: pressure losses due to air viscosity, and air flow separation from a divergent glottis. The optimal glottal configuration seems to be a consequence of the combined effect of both factors. The results agree with the experimental data, showing that the phonation threshold pressure is minimum when the vocal folds are slightly separated in a near rectangular glottis.

Design of MSR primary circuit with minimum pressure losses

NASA Astrophysics Data System (ADS)

Noga, Tomáš; Žitek, Pavel; Valenta, Václav

This article describes a design of a MSR primary circuit with minimum pressure losses. It includes a brief description of this type of a reactor and its integral layout, properties, purpose, etc. The objective of this paper is to define problems of pressure losses calculation and to design a proper device for a primary circuit of MSR reactor, including its basic dimensions. Thanks to this, it can become an initial project for a construction of a real piece of work. This is the main contribution of the carried out study. Of course, this article is not a detailed solution, but it points out facts and problems, which future designers may have to face. The further step of our work will be a reconstruction of the current experiment for a two-stage flowing.

46 CFR 38.05-2 - Design and construction of cargo tanks-general-TB/ALL.

Code of Federal Regulations, 2010 CFR

2010-10-01

... a pressure equal to the setting of the relief valve. (b) The service temperature is the minimum...=Service temperature. t w=Boiling temperature of gas at normal working pressure of tank but not higher than +32 °F. t b=Boiling temperature of gas at atmospheric pressure. (c) Heat transmission studies, where...

46 CFR 38.05-2 - Design and construction of cargo tanks-general-TB/ALL.

Code of Federal Regulations, 2011 CFR

2011-10-01

... a pressure equal to the setting of the relief valve. (b) The service temperature is the minimum...=Service temperature. t w=Boiling temperature of gas at normal working pressure of tank but not higher than +32 °F. t b=Boiling temperature of gas at atmospheric pressure. (c) Heat transmission studies, where...

49 CFR 178.56 - Specification 4AA480 welded steel cylinders.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) Type, size, and service pressure. A DOT 4AA480 cylinder is a welded steel cylinder having a water capacity (nominal) not over 1,000 pounds water capacity and a service pressure of 480 psig. Closures welded... that the calculated wall stress at the minimum test pressure (in paragraph (i) of this section) may not...

49 CFR 178.68 - Specification 4E welded aluminum cylinders.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) Where: S = wall stress in psi; P = minimum test pressure prescribed for water jacket test; D = outside... and service pressure. A DOT 4E cylinder is a welded aluminum cylinder with a water capacity (nominal... stress at twice service pressure may not exceed the lesser value of either of the following: (i) 20,000...

77 FR 19069 - Airworthiness Directives; Goodrich Evacuation Systems Approved Under Technical Standard Order...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-30

... seal and allowed the pressure in certain slides/ rafts to fall below the minimum raft mode pressure for the unit. We are issuing this AD to prevent loss of pressure in the escape slides/rafts after an emergency evacuation, which could result in inadequate buoyancy to support the raft's passenger capacity...

Impaired Central Pulsatile Hemodynamics in Children and Adolescents With Marfan Syndrome.

PubMed

Grillo, Andrea; Salvi, Paolo; Marelli, Susan; Gao, Lan; Salvi, Lucia; Faini, Andrea; Trifirò, Giuliana; Carretta, Renzo; Pini, Alessandro; Parati, Gianfranco

2017-11-07

Marfan syndrome is characterized by aortic root dilation, beginning in childhood. Data about aortic pulsatile hemodynamics and stiffness in pediatric age are currently lacking. In 51 young patients with Marfan syndrome (12.0±3.3 years), carotid tonometry was performed for the measurement of central pulse pressure, pulse pressure amplification, and aortic stiffness (carotid-femoral pulse wave velocity). Patients underwent an echocardiogram at baseline and at 1 year follow-up and a genetic evaluation. Pathogenetic fibrillin-1 mutations were classified between "dominant negative" and "haploinsufficient." The hemodynamic parameters of patients were compared with those of 80 sex, age, blood pressure, and heart-rate matched controls. Central pulse pressure was significantly higher (38.3±12.3 versus 33.6±7.8 mm Hg; P =0.009), and pulse pressure amplification was significantly reduced in Marfan than controls (17.9±15.3% versus 32.3±17.4%; P <0.0001). Pulse wave velocity was not significantly different between Marfan and controls (4.98±1.00 versus 4.75±0.67 m/s). In the Marfan group, central pulse pressure and pulse pressure amplification were independently associated with aortic diameter at the sinuses of Valsalva (respectively, β=0.371, P =0.010; β=-0.271, P =0.026). No significant difference in hemodynamic parameters was found according to fibrillin-1 genotype. Patients who increased aortic Z-scores at 1-year follow-up presented a higher central pulse pressure than the remaining (42.7±14.2 versus 32.3±5.9 mm Hg; P =0.004). Central pulse pressure and pulse pressure amplification were impaired in pediatric Marfan syndrome, and associated with aortic root diameters, whereas aortic pulse wave velocity was similar to that of a general pediatric population. An increased central pulse pressure was present among patients whose aortic dilatation worsened at 1-year follow-up. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

14 CFR 23.1443 - Minimum mass flow of supplemental oxygen.

Code of Federal Regulations, 2011 CFR

2011-01-01

... displaced by water vapor pressure when the breathed air becomes saturated with water vapor at 37 °C). (2) STPD means Standard, Temperature, and Pressure, Dry (which is, 0 °C at 760 mm. Hg with no water vapor...

14 CFR 23.1443 - Minimum mass flow of supplemental oxygen.

Code of Federal Regulations, 2013 CFR

2013-01-01

... displaced by water vapor pressure when the breathed air becomes saturated with water vapor at 37 °C). (2) STPD means Standard, Temperature, and Pressure, Dry (which is 0 °C at 760mm Hg with no water vapor...

14 CFR 23.1443 - Minimum mass flow of supplemental oxygen.

Code of Federal Regulations, 2014 CFR

2014-01-01

... displaced by water vapor pressure when the breathed air becomes saturated with water vapor at 37 °C). (2) STPD means Standard, Temperature, and Pressure, Dry (which is 0 °C at 760mm Hg with no water vapor...

The effect of pressure on the hydration structure around hydrophobic solute: A molecular dynamics simulation study

NASA Astrophysics Data System (ADS)

Sarma, Rahul; Paul, Sandip

2012-03-01

Molecular dynamics simulations are performed to study the effects of pressure on the hydrophobic interactions between neopentane molecules immersed in water. Simulations are carried out for five different pressure values ranging from 1 atm to 8000 atm. From potential of mean force calculations, we find that with enhancement of pressure, there is decrease in the well depth of contact minimum (CM) and the relative stability of solvent separated minimum over CM increases. Lower clustering of neopentane at high pressure is also observed in association constant and cluster-structure analysis. Selected site-site radial distribution functions suggest efficient packing of water molecules around neopentane molecules at elevated pressure. The orientational profile calculations of water molecules show that the orientation of water molecules in the vicinity of solute molecule is anisotropic and this distribution becomes flatter as we move away from the solute. Increasing pressure slightly changes the water distribution. Our hydrogen bond properties and dynamics calculations reveal pressure-induced formation of more and more number of water molecules with five and four hydrogen bond at the expense of breaking of two and three hydrogen bonded water molecules. We also find lowering of water-water continuous hydrogen bond lifetime on application of pressure. Implication of these results for relative dispersion of hydrophobic molecules at high pressure are discussed.

Tritium as an indicator of ground-water age in Central Wisconsin

USGS Publications Warehouse

Bradbury, Kenneth R.

1991-01-01

In regions where ground water is generally younger than about 30 years, developing the tritium input history of an area for comparison with the current tritium content of ground water allows quantitative estimates of minimum ground-water age. The tritium input history for central Wisconsin has been constructed using precipitation tritium measured at Madison, Wisconsin and elsewhere. Weighted tritium inputs to ground water reached a peak of over 2,000 TU in 1964, and have declined since that time to about 20-30 TU at present. In the Buena Vista basin in central Wisconsin, most ground-water samples contained elevated levels of tritium, and estimated minimum ground-water ages in the basin ranged from less than one year to over 33 years. Ground water in mapped recharge areas was generally younger than ground water in discharge areas, and estimated ground-water ages were consistent with flow system interpretations based on other data. Estimated minimum ground-water ages increased with depth in areas of downward ground-water movement. However, water recharging through thick moraine sediments was older than water in other recharge areas, reflecting slower infiltration through the sandy till of the moraine.

NASA Requirements for Ground-Based Pressure Vessels and Pressurized Systems (PVS). Revision C

NASA Technical Reports Server (NTRS)

Greulich, Owen Rudolf

2017-01-01

The purpose of this document is to ensure the structural integrity of PVS through implementation of a minimum set of requirements for ground-based PVS in accordance with this document, NASA Policy Directive (NPD) 8710.5, NASA Safety Policy for Pressure Vessels and Pressurized Systems, NASA Procedural Requirements (NPR) 8715.3, NASA General Safety Program Requirements, applicable Federal Regulations, and national consensus codes and standards (NCS).

Dome of magnetic order inside the nematic phase of sulfur-substituted FeSe under pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiang, Li; Kaluarachchi, Udhara; Bohmer, Anna

2017-07-18

The pressure dependence of the structural, magnetic, and superconducting transitions and of the superconducting upper critical field were studied in sulfur-substituted Fe ( Se 1 - x S x ) . We performed resistance measurements on single crystals with three substitution levels ( x = 0.043 , 0.096, 0.12) under hydrostatic pressures up to 1.8 GPa and in magnetic fields up to 9 T and were compared to data on pure FeSe. Our results illustrate the effects of chemical and physical pressure on Fe ( Se 1 - x S x ). Furthermore, on increasing sulfur content, magnetic order inmore » the low-pressure range is strongly suppressed to a small domelike region in the phase diagrams. But, T s is much less suppressed by sulfur substitution, and T c of Fe ( Se 1 - x S x ) exhibits similar nonmonotonic pressure dependence with a local maximum and a local minimum present in the low-pressure range for all x . The local maximum in T c coincides with the emergence of the magnetic order above T c . At this pressure the slope of the upper critical field decreases abruptly, which may indicate a Fermi-surface reconstruction. The minimum of T c correlates with a broad maximum of the upper critical field slope normalized by T c .« less

Nonfunctioning adrenal incidentaloma affecting central blood pressure and arterial stiffness parameters.

PubMed

Akkan, Tolga; Altay, Mustafa; Ünsal, Yasemin; Dağdeviren, Murat; Beyan, Esin

2017-12-01

Recently, cardiovascular risk is thought to be increased in patients with nonfunctioning adrenal incidentaloma (NFAI). There are no sufficient studies in the literature to evaluate this situation in NFAI patients without cardiovascular risk. The objective of this study is to compare peripheral and central blood pressure and arterial stiffness between patients with NFAI and healthy volunteers (of a similar age, gender and body mass index as the NFAI group) who have no traditional cardiovascular risk factors and autonomous cortisol secretion, with pulse wave analysis (PWA). In this cross-sectional study, we evaluated 35 NFAI patients who have no traditional cardiovascular risk factors and 35 healthy volunteers. PWA was performed in the participants of similar gender, age and body mass index, with a Mobil-O-Graph PWA/ABPM (I.E.M. GmBH, Stolberg, Germany) device. Radiological and biochemical data were obtained retrospectively in the NFAI group. In our study, systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), central SBP, central DBP, peripheral vascular resistance, augmentation pressure (AP), heart rate-corrected augmentation index (Aix@75) and pulse wave velocity (PWV) values were significantly higher in the NFAI group compared to the control group. In addition, peripheral and central blood pressure and arterial stiffness parameters were correlated with age and duration of NFAI diagnosis of more than 1 year. NFAIs are known as cardiometabolically innocent, but in our study, both peripheral and central blood pressure values and arterial stiffness parameters were negatively affected in patients diagnosed with NFAI who have no traditional cardiovascular risk factors. These patients are at risk of cardiovascular diseases.

40 CFR 86.1232-96 - Vehicle preconditioning.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Emission Test Procedures for New Gasoline-Fueled, Natural Gas-Fueled, Liquefied Petroleum Gas-Fueled and... liquefied petroleum gas-fueled vehicles. Prior draining of the fuel tanks is not called for if the fuel in... be filled to a minimum of 75% of service pressure for natural gas-fueled vehicles or a minimum of 75...

Factors determining the level and changes in intra-articular pressure in the knee joint of the dog.

PubMed Central

Nade, S; Newbold, P J

1983-01-01

Intra-articular pressure levels were determined for joint positions throughout the normal physiological range of movement of dogs' knee joints. Change in joint position resulted in change in intra-articular pressure. It was demonstrated that intra-articular pressure is highest with the joint in the fully flexed position. Minimum pressure was recorded at a position between 80 degrees and 120 degrees. Minimum pressures were usually subatmospheric. The rate of change of joint position affected intra-articular pressure. The relationship of intra-articular pressure and joint position before and after full flexion demonstrated a hysteresis effect; the pressures were lower than for the same joint position before flexion. Maintenance of the joint in the fully flexed position for increasing periods of time between repeated movement cycles resulted in a similar reduction, of constant magnitude, in pressure between joint positions before and after each period of flexion. However, there was also a progressive decrease in pressure for all joint angles over the total number of movement cycles. There is a contribution to intra-articular pressure of joint capsular compliance and fluid movement into and out of the joint (both of which are time-dependent). The recording of intra-articular pressure in conscious, upright dogs revealed similar pressure levels to those measured in anaesthetized supine dogs. The major determinants of intra-articular pressure in normal dog knee joints include joint size, synovial fluid volume, position of joint, peri-articular tissue and joint anatomy, membrane permeability, capsular compliance, and movement of fluid into and out of the joint. Images Fig. 1 PMID:6875957

Approximation for the Rayleigh Resolution of a Circular Aperture

ERIC Educational Resources Information Center

Mungan, Carl E.

2009-01-01

Rayleigh's criterion states that a pair of point sources are barely resolved by an optical instrument when the central maximum of the diffraction pattern due to one source coincides with the first minimum of the pattern of the other source. As derived in standard introductory physics textbooks, the first minimum for a rectangular slit of width "a"…

Comparison of the Complior Analyse device with Sphygmocor and Complior SP for pulse wave velocity and central pressure assessment.

PubMed

Stea, Francesco; Bozec, Erwan; Millasseau, Sandrine; Khettab, Hakim; Boutouyrie, Pierre; Laurent, Stéphane

2014-04-01

The Complior device (Alam Medical, France) was used in epidemiological studies which established pulse wave velocity (PWV) as a cardiovascular risk marker. Central pressure is related, but complementary to PWV and also associated to cardiovascular outcomes. The new Complior Analyse measures both PWV and central blood pressure during the same acquisition. The aim of this study was to compare PWV values from Complior Analyse with the previous Complior SP (PWVcs) and with Sphygmocor (PWVscr; AtCor, Australia), and to compare central systolic pressure from Complior Analyse and Sphygmocor. Peripheral and central pressures and PWV were measured with the three devices in 112 patients. PWV measurements from Complior Analyse were analysed using two foot-detection algorithms (PWVca_it and PWVca_cs). Both radial (ao-SBPscr) and carotid (car-SBPscr) approaches from Sphygmocor were compared to carotid Complior Analyse measurements (car-SBPca). The same distance and same calibrating pressures were used for all devices. PWVca_it was strongly correlated to PWVscr (R(2) = 0.93, P < 0.001) with a difference of 0.0 ± 0.7  m/s. PWVca_cs was also correlated to PWVcs (R(2) = 0.90, P < 0.001) with a difference of 0.1 ± 0.7  m/s. Central systolic pressures were strongly correlated. The difference between car-SBPca and ao-SBPscr was 3.1 ± 4.2  mmHg (P < 0.001), statistically equivalent to the difference between car-SBPscr and ao-SBPscr (3.9 ± 5.8  mmHg, P < 0.001), whilst the difference between car-SBPca and car-SBPscr was negligible (-0.7 ± 5.6  mmHg, P = NS). The new Complior Analyse device provides equivalent results for PWV and central pressure values to the Sphygmocor and Complior SP. It reaches Association for the Advancement of Medical Instrumentation standard for central blood pressure and grades as excellent for PWV on the Artery Society criteria. It can be interchanged with existing devices.

Multimodal pressure-flow method to assess dynamics of cerebral autoregulation in stroke and hypertension

PubMed Central

Novak, Vera; Yang, Albert CC; Lepicovsky, Lukas; Goldberger, Ary L; Lipsitz, Lewis A; Peng, Chung-Kang

2004-01-01

Background This study evaluated the effects of stroke on regulation of cerebral blood flow in response to fluctuations in systemic blood pressure (BP). The autoregulatory dynamics are difficult to assess because of the nonstationarity and nonlinearity of the component signals. Methods We studied 15 normotensive, 20 hypertensive and 15 minor stroke subjects (48.0 ± 1.3 years). BP and blood flow velocities (BFV) from middle cerebral arteries (MCA) were measured during the Valsalva maneuver (VM) using transcranial Doppler ultrasound. Results A new technique, multimodal pressure-flow analysis (MMPF), was implemented to analyze these short, nonstationary signals. MMPF analysis decomposes complex BP and BFV signals into multiple empirical modes, representing their instantaneous frequency-amplitude modulation. The empirical mode corresponding to the VM BP profile was used to construct the continuous phase diagram and to identify the minimum and maximum values from the residual BP (BPR) and BFV (BFVR) signals. The BP-BFV phase shift was calculated as the difference between the phase corresponding to the BPR and BFVR minimum (maximum) values. BP-BFV phase shifts were significantly different between groups. In the normotensive group, the BFVR minimum and maximum preceded the BPR minimum and maximum, respectively, leading to large positive values of BP-BFV shifts. Conclusion In the stroke and hypertensive groups, the resulting BP-BFV phase shift was significantly smaller compared to the normotensive group. A standard autoregulation index did not differentiate the groups. The MMPF method enables evaluation of autoregulatory dynamics based on instantaneous BP-BFV phase analysis. Regulation of BP-BFV dynamics is altered with hypertension and after stroke, rendering blood flow dependent on blood pressure. PMID:15504235

Melt inclusion constraints on petrogenesis of the 2014-2015 Holuhraun eruption, Iceland

NASA Astrophysics Data System (ADS)

Hartley, Margaret E.; Bali, Enikö; Maclennan, John; Neave, David A.; Halldórsson, Sæmundur A.

2018-02-01

The 2014-2015 Holuhraun eruption, on the Bárðarbunga volcanic system in central Iceland, was one of the best-monitored basaltic fissure eruptions that has ever occurred, and presents a unique opportunity to link petrological and geochemical data with geophysical observations during a major rifting episode. We present major and trace element analyses of melt inclusions and matrix glasses from a suite of ten samples collected over the course of the Holuhraun eruption. The diversity of trace element ratios such as La/Yb in Holuhraun melt inclusions reveals that the magma evolved via concurrent mixing and crystallization of diverse primary melts in the mid-crust. Using olivine-plagioclase-augite-melt (OPAM) barometry, we calculate that the Holuhraun carrier melt equilibrated at 2.1 ± 0.7 kbar (7.5 ± 2.5 km), which is in agreement with the depths of earthquakes (6 ± 1 km) between Bárðarbunga central volcano and the eruption site in the days preceding eruption onset. Using the same approach, melt inclusions equilibrated at pressures between 0.5 and 8.0 kbar, with the most probable pressure being 3.2 kbar. Diffusion chronometry reveals minimum residence timescales of 1-12 days for melt inclusion-bearing macrocrysts in the Holuhraun carrier melt. By combining timescales of diffusive dehydration of melt inclusions with the calculated pressure of H2O saturation for the Holuhraun magma, we calculate indicative magma ascent rates of 0.12-0.29 m s-1. Our petrological and geochemical data are consistent with lateral magma transport from Bárðarbunga volcano to the eruption site in a shallow- to mid-crustal dyke, as has been suggested on the basis of seismic and geodetic datasets. This result is a significant step forward in reconciling petrological and geophysical interpretations of magma transport during volcano-tectonic episodes, and provides a critical framework for the interpretation of premonitory seismic and geodetic data in volcanically active regions.

Relationships between urinary electrolytes excretion and central hemodynamics, and arterial stiffness in hypertensive patients.

PubMed

Han, Weizhong; Han, Xiao; Sun, Ningling; Chen, Yunchao; Jiang, Shiliang; Li, Min

2017-08-01

High sodium intake plays an important role in the onset and exacerbation of hypertension. However, the relationships between urinary electrolytes excretion and central hemodynamics and between urinary electrolyte excretion and arterial stiffness are still the subject of debate. This study sought to clarify the associations of salt intake with central aortic pressure and arterial stiffness indicators. A total of 431 untreated hypertensive individuals were recruited into the study. Twenty-four-hour urinary samples were collected to measure the excretion of urinary electrolytes. Central hemodynamics parameters and brachial-ankle pulse wave velocity (baPWV) were measured. We evaluated the independent relationship between urinary sodium or potassium excretion and the abovementioned indices. The mean 24-h urinary sodium of all subjects was 166.6±70.0 mmol/24 h. With increases in urinary sodium excretion, central blood pressure and baPWV values markedly increased. Multiple regression analysis showed that urinary sodium was independently associated with increases in central systolic blood pressure, central diastolic blood pressure, the augmentation index, and baPWV. Significant correlations were identified between high dietary sodium and central hemodynamics and between high dietary sodium and arterial elasticity. Prospective interventional studies in hypertensive patients may be required to determine the effect of salt intake on central hemodynamics.

Double-cross hydrostatic pressure sample injection for chip CE: variable sample plug volume and minimum number of electrodes.

PubMed

Luo, Yong; Wu, Dapeng; Zeng, Shaojiang; Gai, Hongwei; Long, Zhicheng; Shen, Zheng; Dai, Zhongpeng; Qin, Jianhua; Lin, Bingcheng

2006-09-01

A novel sample injection method for chip CE was presented. This injection method uses hydrostatic pressure, generated by emptying the sample waste reservoir, for sample loading and electrokinetic force for dispensing. The injection was performed on a double-cross microchip. One cross, created by the sample and separation channels, is used for formation of a sample plug. Another cross, formed by the sample and controlling channels, is used for plug control. By varying the electric field in the controlling channel, the sample plug volume can be linearly adjusted. Hydrostatic pressure takes advantage of its ease of generation on a microfluidic chip, without any electrode or external pressure pump, thus allowing a sample injection with a minimum number of electrodes. The potential of this injection method was demonstrated by a four-separation-channel chip CE system. In this system, parallel sample separation can be achieved with only two electrodes, which is otherwise impossible with conventional injection methods. Hydrostatic pressure maintains the sample composition during the sample loading, allowing the injection to be free of injection bias.

Preliminary Data on the Effects of Inlet Pressure Distortions on the J57-P-1 Turbojet Engine

NASA Technical Reports Server (NTRS)

Wallner, Lewis E.; Lubick, Robert J.; Einstein, Thomas H.

1954-01-01

An investigation to determine the steady-state and surge characteristics of the J57-P-1 two-spool turbojet engine with various inlet air-flow distortions was conducted in the altitude wind tunnel at the NACA Lewis laboratory. Along with a uniform inlet total-pressure distribution, one circumferential and three radial pressure distortions were investigated. Data were obtained over a complete range of compressor speeds both with and without intercompressor air bleed at a flight Mach number of 0.8 and at altitudes of 35,000 and 50,000 feet. Total-pressure distortions of the magnitudes investigated had very little effect on the steady-state operating line for either the outer or inner compressor. The small radial distortions investigated also had engine over that obtained with the uniform inlet pressure distribution. The circumferential distortion, however, raised the minimum speed at which the engine could operate without encountering surge when the intercompressor bleeds were closed. This increase in minimum speed resulted in a substantial reduction in the operable speed range accompanied by a reduction in the altitude operating limit.

30 CFR 250.1003 - Installation, testing, and repair requirements for DOI pipelines.

Code of Federal Regulations, 2011 CFR

2011-07-01

... installed in water depths of less than 200 feet shall be buried to a depth of at least 3 feet unless they... damage potential exists. (b)(1) Pipelines shall be pressure tested with water at a stabilized pressure of... repair, the pipeline shall be pressure tested with water or processed natural gas at a minimum stabilized...

External Catalyst Breakup Phenomena

DTIC Science & Technology

1976-06-01

catalyst particle can cause high internal pressures which result in particle destruction. Analytical results suggest rhat erosion effects from solid...mechanisms. * Pressure Forces. High G loadings and bed pressure drops should be avoided. Bed pre-loads should be kept at a minimum value. Thruster...5.2.7.1 Failure Theories ............................ 243 5.2.7.2 Maximum Tension Stress Criterion ............ 244 5.2.7.3 Distortion Energy Approach

30 CFR 250.523 - How long do I keep records of casing pressure and diagnostic tests?

Code of Federal Regulations, 2011 CFR

2011-07-01

... and diagnostic tests? 250.523 Section 250.523 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT... long do I keep records of casing pressure and diagnostic tests? Records of casing pressure and diagnostic tests must be kept at the field office nearest the well for a minimum of 2 years. The last casing...

14 CFR 23.1443 - Minimum mass flow of supplemental oxygen.

Code of Federal Regulations, 2012 CFR

2012-01-01

..., minus 47 mm. Hg, which is the tracheal pressure displaced by water vapor pressure when the breathed air becomes saturated with water vapor at 37 °C). (2) STPD means Standard, Temperature, and Pressure, Dry (which is, 0 °C at 760 mm. Hg with no water vapor). [Doc. No. 26344, 58 FR 18978, Apr. 9, 1993] § 23.1443...

Laser ignition of liquid petroleum gas at elevated pressures

NASA Astrophysics Data System (ADS)

Loktionov, E.; Pasechnikov, N.; Telekh, V.

2017-11-01

Recent development of laser spark plugs for internal combustion engines have shown lack of data on laser ignition of fuel mixtures at multi-bar pressures needed for laser pulse energy and focusing optimisation. Methane and hydrogen based mixtures are comparatively well investigated, but propane and butane based ones (LPG), which are widely used in vehicles, are still almost unstudied. Optical breakdown thresholds in gases decrease with pressure increase up to ca. 100 bar, but breakdown is not a sufficient condition for combustion ignition. So minimum ignition energy (MIE) becomes more important for combustion core onset, and its dependency on mixture composition and pressure has several important features. For example, unlike breakdown threshold, is poorly dependent on laser pulse length, at least in pico- and to microsecond range. We have defined experimentally the dependencies of minimum picosecond laser pulse energies (MIE related value) needed for ignition of LPG based mixtures of 1.0 to 1.6 equivalence ratios and pressure of 1.0 to 3.5 bar. In addition to expected values decrease, low-energy flammability range broadening has been found at pressure increase. Laser ignition of LPG in Wankel rotary engine is reported for the first time.

Association between central obesity and circadian parameters of blood pressure from the korean ambulatory blood pressure monitoring registry: Kor-ABP registry.

PubMed

Kang, In Sook; Pyun, Wook Bum; Shin, Jinho; Kim, Ju Han; Kim, Soon Gil; Shin, Gil Ja

2013-10-01

Central obesity has been reported as a risk for atherosclerosis and metabolic syndrome. The influence of central obesity on diurnal blood pressure (BP) has not been established. In this study, we investigated the influence of central obesity on the circadian parameters of BP by 24 hr ambulatory BP monitoring. Total 1,290 subjects were enrolled from the Korean Ambulatory BP registry. Central obesity was defined as having a waist circumference≥90 cm in males and ≥85 cm in females. The central-obese group had higher daytime systolic BP (SBP), nighttime SBP and diastolic BP (DBP) than the non-obese group (all, P<0.001). There were no differences in nocturnal dipping (ND) patterns between the groups. Female participants showed a higher BP mean difference (MD) than male participants with concerns of central obesity (daytime SBP MD 5.28 vs 4.27, nighttime SBP MD 6.48 vs 2.72) and wider pulse pressure (PP). Central obesity within the elderly (≥65 yr) also showed a higher BP MD than within the younger group (daytime SBP MD 8.23 vs 3.87, daytime DBP 4.10 vs 1.59). In conclusion, central obesity has no influence on nocturnal dipping patterns. However, higher SBP and wider PP are associated with central obesity, which is accentuated in women.

Note: measurement of extreme-short current pulse duration of runaway electron beam in atmospheric pressure air.

PubMed

Tarasenko, V F; Rybka, D V; Burachenko, A G; Lomaev, M I; Balzovsky, E V

2012-08-01

This note reports the time-amplitude characteristic of the supershort avalanche electron beam with up to 20 ps time resolution. For the first time it is shown that the electron beam downstream of small-diameter diaphragms in atmospheric pressure air has a complex structure which depends on the interelectrode gap width and cathode design. With a spherical cathode and collimator the minimum duration at half maximum of the supershort avalanche electron beam current pulse was shown to be ~25 ps. The minimum duration at half maximum of one peak in the pulses with two peaks can reach ~25 ps too.

Magnetic energy dissipation in force-free jets

NASA Technical Reports Server (NTRS)

Choudhuri, Arnab Rai; Konigl, Arieh

1986-01-01

It is shown that a magnetic pressure-dominated, supersonic jet which expands or contracts in response to variations in the confining external pressure can dissipate magnetic energy through field-line reconnection as it relaxes to a minimum-energy configuration. In order for a continuous dissipation to occur, the effective reconnection time must be a fraction of the expansion time. The dissipation rate for the axisymmetric minimum-energy field configuration is analytically derived. The results indicate that the field relaxation process could be a viable mechanism for powering the synchrotron emission in extragalactic jets if the reconnection time is substantially shorter than the nominal resistive tearing time in the jet.

Torrejon AB, Madrid, Spain. revised uniform summary of surface weather observations (RUSSWO). parts a-f. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1978-10-03

This report is a six-part statistical summary of surface weather observations for Torrejon AB, Madrid Spain. It contains the following parts: (A) Weather Conditions; Atmospheric Phenomena; (B) Precipitation, Snowfall and Snow Depth (daily amounts and extreme values); (C) Surface winds; (D) Ceiling Versus Visibility; Sky Cover; (E) Psychrometric Summaries (daily maximum and minimum temperatures, extreme maximum and minimum temperatures, psychrometric summary of wet-bulb temperature depression versus dry-bulb temperature, means and standard deviations of dry-bulb, wet-bulb and dew-point temperatures and relative humidity); and (F) Pressure Summary (means, standard, deviations, and observation counts of station pressure and sea-level pressure). Data in thismore » report are presented in tabular form, in most cases in percentage frequency of occurrence or cumulative percentage frequency of occurrence tables.« less

Habitual intake of fruit juice predicts central blood pressure.

PubMed

Pase, Matthew P; Grima, Natalie; Cockerell, Robyn; Pipingas, Andrew

2015-01-01

Despite a common perception that fruit juice is healthy, fruit juice contains high amounts of naturally occurring sugar without the fibre content of the whole fruit. Frequent fruit juice consumption may therefore contribute to excessive sugar consumption typical of the Western society. Although excess sugar intake is associated with high blood pressure (BP), the association between habitual fruit juice consumption and BP is unclear. The present study investigated the association of fruit juice consumption with brachial and central (aortic) BP in 160 community dwelling adults. Habitual fruit juice consumption was measured using a 12 month dietary recall questionnaire. On the same day, brachial BP was measured and central (aortic) BP was estimated through radial artery applanation. Frequency of fruit juice consumption was classified as rare, occasional or daily. Those who consumed fruit juice daily, versus rarely or occasionally, had significantly higher central systolic BP (F (2, 134) = 6.09, p <0.01), central pulse pressure (F (2, 134) = 4.16, p <0.05), central augmentation pressure (F (2, 134) = 5.98, p <0.01) and central augmentation index (F (2, 134) = 3.29, p <0.05) as well as lower pulse pressure amplification (F (2, 134) = 4.36, p <0.05). There were no differences in brachial BP. Central systolic BP was 3-4 mmHg higher for those who consumed fruit juice daily rather than rarely or occasionally. In conclusion, more frequent fruit juice consumption was associated with higher central BPs. Copyright © 2014 Elsevier Ltd. All rights reserved.

Vortex servovalve for fluidic or electrical input

NASA Technical Reports Server (NTRS)

Honda, T. S.

1972-01-01

Proportional-pressure control servovalve consisting of fluid amplifier bellows-driven jet-pipe and two vortex valves operating in push-pull, with a pair of bellows for pressure feedback is tolerant to comtaminant particles and meets minimum standby flow requirements for applications such as rocket thruster nozzles.

Effects of Sacubitril/Valsartan Versus Olmesartan on Central Hemodynamics in the Elderly With Systolic Hypertension: The PARAMETER Study.

PubMed

Williams, Bryan; Cockcroft, John R; Kario, Kazuomi; Zappe, Dion H; Brunel, Patrick C; Wang, Qian; Guo, Weinong

2017-03-01

Effective treatment of systolic hypertension in elderly patients remains a major therapeutic challenge. A multicenter, double-blind, randomized controlled trial with sacubitril/valsartan (LCZ696), a first-in-class angiotensin receptor neprilysin inhibitor, was conducted to determine its effects versus olmesartan (angiotensin receptor blocker) on central aortic pressures, in elderly patients (aged ≥60 years) with systolic hypertension and pulse pressure >60 mm Hg, indicative of arterial stiffness. Patients (n=454; mean age, 67.7 years; mean seated systolic blood pressure, 158.6 mm Hg; mean seated pulse pressure, 69.7 mm Hg) were randomized to receive once-daily sacubitril/valsartan 200 mg or olmesartan 20 mg, force titrated to double the initial doses after 4 weeks, before primary assessment at 12 weeks. The study extended double-blind treatment for 12 to 52 weeks, during which amlodipine (2.5-5 mg) and subsequently hydrochlorothiazide (6.25-25 mg) were added-on for patients not achieving blood pressure target (<140/90). At week 12, sacubitril/valsartan reduced central aortic systolic pressure (primary assessment) greater than olmesartan by -3.7 mm Hg ( P =0.010), further corroborated by secondary assessments at week 12 (central aortic pulse pressure, -2.4 mm Hg, P <0.012; mean 24-hour ambulatory brachial systolic blood pressure and central aortic systolic pressure, -4.1 mm Hg and -3.6 mm Hg, respectively, both P <0.001). Differences in 24-hour ambulatory pressures were pronounced during sleep. After 52 weeks, blood pressure parameters were similar between treatments ( P <0.002); however, more patients required add-on antihypertensive therapy with olmesartan (47%) versus sacubitril/valsartan (32%; P <0.002). Both treatments were equally well tolerated. The PARAMETER study (Prospective Comparison of Angiotensin Receptor Neprilysin Inhibitor With Angiotensin Receptor Blocker Measuring Arterial Stiffness in the Elderly), for the first time, demonstrated superiority of sacubitril/valsartan versus olmesartan in reducing clinic and ambulatory central aortic and brachial pressures in elderly patients with systolic hypertension and stiff arteries. © 2017 American Heart Association, Inc.

An analysis of data related to the minimum temperatures for valid testing in cryogenic wind tunnels using nitrogen as the test gas

NASA Technical Reports Server (NTRS)

Hall, R. M.

1976-01-01

The minimum operating temperature which avoids adverse low temperature effects, such as condensation, has been determined at a free stream Mach number of 0.85 for flow over a 0.137 meter airfoil mounted at zero incidence in the Langley 1/3 meter transonic cryogenic tunnel. The onset of low temperature effects is established by comparing the pressure coefficient measured at a given orifice for a particular temperature with those measured at temperatures sufficiently above where low temperature effects might be expected to occur. The pressure distributions over the airfoil are presented in tabular form. In addition, the comparisons of the pressure coefficient as a function of total temperature are presented graphically for chord locations of 0, 25, 50, and 75 percent. Over the 1.2 to 4.5 atmosphere total pressure range investigated, low temperature effects are not detected until total temperatures are 2 K, or more, below free stream saturation temperatures.

49 CFR 178.47 - Specification 4DS welded stainless steel cylinders for aircraft use.

Code of Federal Regulations, 2011 CFR

2011-10-01

... the formula: S = PD / 4tE Where: S = Wall stress in psi; P = Test pressure prescribed for water jacket... stainless steel sphere (two seamless hemispheres) or circumferentially welded cylinder both with a water... thickness. The minimum wall thickness must be such that the wall stress at the minimum specified test...

Elastohydrodynamic lubrication of elliptical contacts

NASA Technical Reports Server (NTRS)

Hamrock, B. J.

1981-01-01

The determination of the minimum film thickness within contact is considered for both fully flooded and starved conditions. A fully flooded conjunction is one in which the film thickness is not significantly changed when the amount of lubricant is increased. The fully flooded results presented show the influence of contact geometry on minimum film thickness as expressed by the ellipticity parameter and the dimensionless speed, load, and materials parameters. These results are applied to materials of high elastic modulus (hard EHL), such as metal, and to materials of low elastic modulus(soft EHL), such as rubber. In addition to the film thickness equations that are developed, contour plots of pressure and film thickness are given which show the essential features of elastohydrodynamically lubricated conjunctions. The crescent shaped region of minimum film thickness, with its side lobes in which the separation between the solids is a minimum, clearly emerges in the numerical solutions. In addition to the 3 presented for the fully flooded results, 15 more cases are used for hard EHL contacts and 18 cases are used for soft EHL contacts in a theoretical study of the influence of lubricant starvation on film thickness and pressure. From the starved results for both hard and soft EHL contacts, a simple and important dimensionless inlet boundary distance is specified. This inlet boundary distance defines whether a fully flooded or a starved condition exists in the contact. Contour plots of pressure and film thickness in and around the contact are shown for conditions.

Computational fluid dynamics endpoints to characterize obstructive sleep apnea syndrome in children

PubMed Central

Luo, Haiyan; Persak, Steven C.; Sin, Sanghun; McDonough, Joseph M.; Isasi, Carmen R.; Arens, Raanan

2013-01-01

Computational fluid dynamics (CFD) analysis may quantify the severity of anatomical airway restriction in obstructive sleep apnea syndrome (OSAS) better than anatomical measurements alone. However, optimal CFD model endpoints to characterize or assess OSAS have not been determined. To model upper airway fluid dynamics using CFD and investigate the strength of correlation between various CFD endpoints, anatomical endpoints, and OSAS severity, in obese children with OSAS and controls. CFD models derived from magnetic resonance images were solved at subject-specific peak tidal inspiratory flow; pressure at the choanae was set by nasal resistance. Model endpoints included airway wall minimum pressure (Pmin), flow resistance in the pharynx (Rpharynx), and pressure drop from choanae to a minimum cross section where tonsils and adenoids constrict the pharynx (dPTAmax). Significance of endpoints was analyzed using paired comparisons (t-test or Wilcoxon signed rank test) and Spearman correlation. Fifteen subject pairs were analyzed. Rpharynx and dPTAmax were higher in OSAS than control and most significantly correlated to obstructive apnea-hypopnea index (oAHI), r = 0.48 and r = 0.49, respectively (P < 0.01). Airway minimum cross-sectional correlation to oAHI was weaker (r = −0.39); Pmin was not significantly correlated. CFD model endpoints based on pressure drops in the pharynx were more closely associated with the presence and severity of OSAS than pressures including nasal resistance, or anatomical endpoints. This study supports the usefulness of CFD to characterize anatomical restriction of the pharynx and as an additional tool to evaluate subjects with OSAS. PMID:24265282

Rail vs truck transport of biomass.

PubMed

Mahmudi, Hamed; Flynn, Peter C

2006-01-01

This study analyzes the economics of transshipping biomass from truck to train in a North American setting. Transshipment will only be economic when the cost per unit distance of a second transportation mode is less than the original mode. There is an optimum number of transshipment terminals which is related to biomass yield. Transshipment incurs incremental fixed costs, and hence there is a minimum shipping distance for rail transport above which lower costs/km offset the incremental fixed costs. For transport by dedicated unit train with an optimum number of terminals, the minimum economic rail shipping distance for straw is 170 km, and for boreal forest harvest residue wood chips is 145 km. The minimum economic shipping distance for straw exceeds the biomass draw distance for economically sized centrally located power plants, and hence the prospects for rail transport are limited to cases in which traffic congestion from truck transport would otherwise preclude project development. Ideally, wood chip transport costs would be lowered by rail transshipment for an economically sized centrally located power plant, but in a specific case in Alberta, Canada, the layout of existing rail lines precludes a centrally located plant supplied by rail, whereas a more versatile road system enables it by truck. Hence for wood chips as well as straw the economic incentive for rail transport to centrally located processing plants is limited. Rail transshipment may still be preferred in cases in which road congestion precludes truck delivery, for example as result of community objections.

The small-x gluon distribution in centrality biased pA and pp collisions

DOE PAGES

Dumitru, Adrian; Kapilevich, Gary; Skokov, Vladimir

2018-04-04

Here, the nuclear modification factor R pA(p T) provides information on the small- x gluon distribution of a nucleus at hadron colliders. Several experiments have recently measured the nuclear modification factor not only in minimum bias but also for central pA collisions. In this paper we analyze the bias on the configurations of soft gluon fields introduced by a centrality selection via the number of hard particles. Such bias can be viewed as reweighting of configurations of small- x gluons. We find that the biased nuclear modification factor Q pA(p T) for central collisions is above R pA(p T) formore » minimum bias events, and that it may redevelop a “Cronin peak” even at small x . The magnitude of the peak is predicted to increase approximately like 1/A ⊥ ν, ν~0.6±0.1 , if one is able to select more compact configurations of the projectile proton where its gluons occupy a smaller transverse area A ⊥. We predict an enhanced Q pp(p T)–1~1/(p T 2) ν and a Cronin peak even for central pp collisions.« less

The small-x gluon distribution in centrality biased pA and pp collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dumitru, Adrian; Kapilevich, Gary; Skokov, Vladimir

Here, the nuclear modification factor R pA(p T) provides information on the small- x gluon distribution of a nucleus at hadron colliders. Several experiments have recently measured the nuclear modification factor not only in minimum bias but also for central pA collisions. In this paper we analyze the bias on the configurations of soft gluon fields introduced by a centrality selection via the number of hard particles. Such bias can be viewed as reweighting of configurations of small- x gluons. We find that the biased nuclear modification factor Q pA(p T) for central collisions is above R pA(p T) formore » minimum bias events, and that it may redevelop a “Cronin peak” even at small x . The magnitude of the peak is predicted to increase approximately like 1/A ⊥ ν, ν~0.6±0.1 , if one is able to select more compact configurations of the projectile proton where its gluons occupy a smaller transverse area A ⊥. We predict an enhanced Q pp(p T)–1~1/(p T 2) ν and a Cronin peak even for central pp collisions.« less

Measurement of central venous pressure and determination of hormones in blood serum during weightlessness

NASA Technical Reports Server (NTRS)

Kirsch, K.

1981-01-01

A Spacelab experiment is described which proposes to obtain data on the degree of engorgement of the cephalad circulation during weightlessness by recording central venous pressure. Of practical importance is the question of how close the astronauts are to pulmonary edema and whether the pressure falls toward normal during the time of the mission. Another experiment to investigate deviations from normal fluid and mineral metabolism, possibly initiated by the central engorgement of the low pressure system, is discussed. Hormones responsible for the control of water and mineral balance (vasopressin, catecholamines, renin, aldosterone, corticosteroids, and prostaglandin E1) will be analyzed from blood samples.

Methodology and technology for peripheral and central blood pressure and blood pressure variability measurement: current status and future directions - Position statement of the European Society of Hypertension Working Group on blood pressure monitoring and cardiovascular variability.

PubMed

Stergiou, George S; Parati, Gianfranco; Vlachopoulos, Charalambos; Achimastos, Apostolos; Andreadis, Emanouel; Asmar, Roland; Avolio, Alberto; Benetos, Athanase; Bilo, Grzegorz; Boubouchairopoulou, Nadia; Boutouyrie, Pierre; Castiglioni, Paolo; de la Sierra, Alejandro; Dolan, Eamon; Head, Geoffrey; Imai, Yutaka; Kario, Kazuomi; Kollias, Anastasios; Kotsis, Vasilis; Manios, Efstathios; McManus, Richard; Mengden, Thomas; Mihailidou, Anastasia; Myers, Martin; Niiranen, Teemu; Ochoa, Juan Eugenio; Ohkubo, Takayoshi; Omboni, Stefano; Padfield, Paul; Palatini, Paolo; Papaioannou, Theodore; Protogerou, Athanasios; Redon, Josep; Verdecchia, Paolo; Wang, Jiguang; Zanchetti, Alberto; Mancia, Giuseppe; O'Brien, Eoin

2016-09-01

Office blood pressure measurement has been the basis for hypertension evaluation for almost a century. However, the evaluation of blood pressure out of the office using ambulatory or self-home monitoring is now strongly recommended for the accurate diagnosis in many, if not all, cases with suspected hypertension. Moreover, there is evidence that the variability of blood pressure might offer prognostic information that is independent of the average blood pressure level. Recently, advancement in technology has provided noninvasive evaluation of central (aortic) blood pressure, which might have attributes that are additive to the conventional brachial blood pressure measurement. This position statement, developed by international experts, deals with key research and practical issues in regard to peripheral blood pressure measurement (office, home, and ambulatory), blood pressure variability, and central blood pressure measurement. The objective is to present current achievements, identify gaps in knowledge and issues concerning clinical application, and present relevant research questions and directions to investigators and manufacturers for future research and development (primary goal).

Central hemodynamics and arterial stiffness in idiopathic and multiple system atrophy.

PubMed

Franzen, Klaas; Fliegen, Sabine; Koester, Jelena; Martin, Rafael Campos; Deuschl, Günther; Reppel, Michael; Mortensen, Kai; Schneider, Susanne A

2017-02-01

Blood pressure is commonly abnormal in parkinsonian disorders, but central hemodynamics and arterial stiffness, well-established predictors of total cardiovascular risk, have rarely been studied in these disorders. 32 patients [27 with idiopathic Parkinson's disease (iPD); 5 with multiple system atrophy (MSA)] and 15 controls matched for cardiac risk factors underwent 24 h-ambulatory blood pressure recordings using an I.E.M. device (Mobil-O-Graph™), measuring peripheral pressure and calculating central pressures and arterial stiffness. Mean augmentation indices corrected for heart rate (AIx@75) were significantly lower and pulse wave velocities were significantly elevated in patients compared to controls. Central systolic blood pressure, cardiac output and daytime total vascular resistance were significantly elevated in patients. Mean nocturnal systolic peripheral blood pressure and nocturnal heart rates were also significantly higher; 56.3% of patients had nocturnal hypertension (80% of the MSA group); 85.2% showed non-dipping. This supports previous findings of reduced vulnerability to systemic atherosclerosis and end-organ damage in treated PD. Yet, hemodynamic abnormalities were common and often remained asymptomatic.

Locating and sealing air leaks in multiroomed buildings

NASA Technical Reports Server (NTRS)

Britton, J. M.

1968-01-01

Industrial, nontoxic smoke bombs are used in multiroomed buildings to locate and fill discovered leak areas with polyurethane foam. All obvious air escape routes are sealed and the room is then pressurized to a minimum of 0.1 inch water above the pressure of adjoining rooms.

Pressure fluctuation generated by the interaction of blade and tongue

NASA Astrophysics Data System (ADS)

Zheng, Lulu; Dou, Hua-Shu; Chen, Xiaoping; Zhu, Zuchao; Cui, Baoling

2018-02-01

Pressure fluctuation around the tongue has large effect on the stable operation of a centrifugal pump. In this paper, the Reynolds averaged Navier-Stokes equations (RANS) and the RNG k-epsilon turbulence model is employed to simulate the flow in a pump. The flow field in the centrifugal pump is computed for a range of flow rate. The simulation results have been compared with the experimental data and good agreement has been achieved. In order to study the interaction of the tongue with the impeller, fifteen monitor probes are evenly distributed circumferentially at three radii around the tongue. Pressure distribution is investigated at various blade positions while the blade approaches to and leaves the tongue region. Results show that pressure signal fluctuates largely around the tongue, and it is more intense near the tongue surface. At design condition, standard deviation of pressure fluctuation is the minimum. At large flow rate, the increased low pressure region at the blade trailing edge results in the increases of pressure fluctuation amplitude and pressure spectra at the monitor probes. Minimum pressure is obtained when the blade is facing to the tongue. It is found that the amplitude of pressure fluctuation strongly depends on the blade positions at large flow rate, and pressure fluctuation is caused by the relative movement between blades and tongue. At small flow rate, the rule of pressure fluctuation is mainly depending on the structure of vortex flow at blade passage exit besides the influence from the relative position between the blade and the tongue.

Automatic safety rod for reactors. [LMFBR

DOEpatents

Germer, J.H.

1982-03-23

An automatic safety rod for a nuclear reactor containing neutron absorbing material and designed to be inserted into a reactor core after a loss-of-flow. Actuation is based upon either a sudden decrease in core pressure drop or the pressure drop decreases below a predetermined minimum value. The automatic control rod includes a pressure regulating device whereby a controlled decrease in operating pressure due to reduced coolant flow does not cause the rod to drop into the core.

Automatic safety rod for reactors

DOEpatents

Germer, John H.

1988-01-01

An automatic safety rod for a nuclear reactor containing neutron absorbing material and designed to be inserted into a reactor core after a loss-of-core flow. Actuation is based upon either a sudden decrease in core pressure drop or the pressure drop decreases below a predetermined minimum value. The automatic control rod includes a pressure regulating device whereby a controlled decrease in operating pressure due to reduced coolant flow does not cause the rod to drop into the core.

Numerical Modelling of Extended Leak-Off Test with a Pre-Existing Fracture

NASA Astrophysics Data System (ADS)

Lavrov, A.; Larsen, I.; Bauer, A.

2016-04-01

Extended leak-off test (XLOT) is one of the few techniques available for stress measurements in oil and gas wells. Interpretation of the test is often difficult since the results depend on a multitude of factors, including the presence of natural or drilling-induced fractures in the near-well area. Coupled numerical modelling of XLOT has been performed to investigate the pressure behaviour during the flowback phase as well as the effect of a pre-existing fracture on the test results in a low-permeability formation. Essential features of XLOT known from field measurements are captured by the model, including the saw-tooth shape of the pressure vs injected volume curve, and the change of slope in the pressure vs time curve during flowback used by operators as an indicator of the bottomhole pressure reaching the minimum in situ stress. Simulations with a pre-existing fracture running from the borehole wall in the radial direction have revealed that the results of XLOT are quite sensitive to the orientation of the pre-existing fracture. In particular, the fracture initiation pressure and the formation breakdown pressure increase steadily with decreasing angle between the fracture and the minimum in situ stress. Our findings seem to invalidate the use of the fracture initiation pressure and the formation breakdown pressure for stress measurements or rock strength evaluation purposes.

40 CFR 63.9921 - What are the installation, operation and maintenance requirements for my monitors?

Code of Federal Regulations, 2010 CFR

2010-07-01

... operating limits in § 63.9890(b) for pressure drop and scrubber water flow rate, you must install, operate...) For the pressure drop CPMS, you must: (i) Locate the pressure sensor(s) in or as close to a position... sensitivity of 0.5 inch of water or a transducer with a minimum measurement sensitivity of 1 percent of the...

42 CFR 84.149 - Type C supplied-air respirator, demand and pressure demand class; minimum requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... per square inch) with from 6 to 76 m. (15 to 250 feet) of air-supply hose. (c) The specified air... pounds per square inch gage). (d)(1) Where the pressure in the air-supply system exceeds 863 kN/m.2 (125 pounds per square inch gage), the respirator shall be equipped with a pressure-release mechanism that...

42 CFR 84.149 - Type C supplied-air respirator, demand and pressure demand class; minimum requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... per square inch) with from 6 to 76 m. (15 to 250 feet) of air-supply hose. (c) The specified air... pounds per square inch gage). (d)(1) Where the pressure in the air-supply system exceeds 863 kN/m.2 (125 pounds per square inch gage), the respirator shall be equipped with a pressure-release mechanism that...

42 CFR 84.149 - Type C supplied-air respirator, demand and pressure demand class; minimum requirements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... per square inch) with from 6 to 76 m. (15 to 250 feet) of air-supply hose. (c) The specified air... pounds per square inch gage). (d)(1) Where the pressure in the air-supply system exceeds 863 kN/m.2 (125 pounds per square inch gage), the respirator shall be equipped with a pressure-release mechanism that...

42 CFR 84.149 - Type C supplied-air respirator, demand and pressure demand class; minimum requirements.

Code of Federal Regulations, 2013 CFR

2013-10-01

... per square inch) with from 6 to 76 m. (15 to 250 feet) of air-supply hose. (c) The specified air... pounds per square inch gage). (d)(1) Where the pressure in the air-supply system exceeds 863 kN/m.2 (125 pounds per square inch gage), the respirator shall be equipped with a pressure-release mechanism that...

42 CFR 84.149 - Type C supplied-air respirator, demand and pressure demand class; minimum requirements.

Code of Federal Regulations, 2014 CFR

2014-10-01

... per square inch) with from 6 to 76 m. (15 to 250 feet) of air-supply hose. (c) The specified air... pounds per square inch gage). (d)(1) Where the pressure in the air-supply system exceeds 863 kN/m.2 (125 pounds per square inch gage), the respirator shall be equipped with a pressure-release mechanism that...

49 CFR 232.217 - Train brake tests conducted using yard air.

Code of Federal Regulations, 2013 CFR

2013-10-01

... reduction of brake pipe air pressure at the same, or slower, rate as an engineer's brake valve. (b) The yard... (f). (2) At a minimum, yard air pressure shall be 60 psi at the end of the consist or block of cars... device. (3) If the air pressure of the yard test device is less than 80 psi, then a brake pipe leakage or...

49 CFR 232.217 - Train brake tests conducted using yard air.

Code of Federal Regulations, 2014 CFR

2014-10-01

... reduction of brake pipe air pressure at the same, or slower, rate as an engineer's brake valve. (b) The yard... (f). (2) At a minimum, yard air pressure shall be 60 psi at the end of the consist or block of cars... device. (3) If the air pressure of the yard test device is less than 80 psi, then a brake pipe leakage or...

49 CFR 232.217 - Train brake tests conducted using yard air.

Code of Federal Regulations, 2012 CFR

2012-10-01

... reduction of brake pipe air pressure at the same, or slower, rate as an engineer's brake valve. (b) The yard... (f). (2) At a minimum, yard air pressure shall be 60 psi at the end of the consist or block of cars... device. (3) If the air pressure of the yard test device is less than 80 psi, then a brake pipe leakage or...

49 CFR 232.217 - Train brake tests conducted using yard air.

Code of Federal Regulations, 2011 CFR

2011-10-01

... reduction of brake pipe air pressure at the same, or slower, rate as an engineer's brake valve. (b) The yard... (f). (2) At a minimum, yard air pressure shall be 60 psi at the end of the consist or block of cars... device. (3) If the air pressure of the yard test device is less than 80 psi, then a brake pipe leakage or...

Adiposity and Blood Pressure in 110 000 Mexican Adults

PubMed Central

Gnatiuc, Louisa; Halsey, Jim; Herrington, William G.; López-Cervantes, Malaquías; Lewington, Sarah; Collins, Rory; Tapia-Conyer, Roberto; Peto, Richard; Kuri-Morales, Pablo

2017-01-01

Previous studies have reached differing conclusions about the importance of general versus central markers of adiposity to blood pressure, leading to suggestions that population-specific adiposity thresholds may be needed. We examined the relevance of adiposity to blood pressure among 111 911 men and women who, when recruited into the Mexico City Prospective Study, were aged 35 to 89 years, had no chronic disease, and were not taking antihypertensives. Linear regression was used to estimate the effects on systolic and diastolic blood pressure of 2 markers of general adiposity (body mass index and height-adjusted weight) and 4 markers of central adiposity (waist circumference, hip circumference, waist:hip ratio, and waist:height ratio), adjusted for relevant confounders. Mean (SD) adiposity levels were: body mass index (28.7±4.5 kg/m2), height-adjusted weight (70.2±11.2 kg), waist circumference (93.3±10.6 cm), hip circumference (104.0±9.0 cm), waist:hip ratio (0.90±0.06), and waist:height ratio (0.60±0.07). Associations with blood pressure were linear with no threshold levels below which lower general or central adiposity was not associated with lower blood pressure. On average, each 1 SD higher measured adiposity marker was associated with a 3 mm Hg higher systolic blood pressure and 2 mm Hg higher diastolic blood pressure (SEs <0.1 mm Hg), but for the waist:hip ratio, associations were only approximately half as strong. General adiposity associations were independent of central adiposity, but central adiposity associations were substantially reduced by adjustment for general adiposity. Findings were similar for men and women. In Mexican adults, often overweight or obese, markers of general adiposity were stronger independent predictors of blood pressure than measured markers of central adiposity, with no threshold effects. PMID:28223471

Physical understanding of the tropical cyclone wind-pressure relationship.

PubMed

Chavas, Daniel R; Reed, Kevin A; Knaff, John A

2017-11-08

The relationship between the two common measures of tropical cyclone intensity, the central pressure deficit and the peak near-surface wind speed, is a long-standing problem in tropical meteorology that has been approximated empirically yet lacks physical understanding. Here we provide theoretical grounding for this relationship. We first demonstrate that the central pressure deficit is highly predictable from the low-level wind field via gradient wind balance. We then show that this relationship reduces to a dependence on two velocity scales: the maximum azimuthal-mean azimuthal wind speed and half the product of the Coriolis parameter and outer storm size. This simple theory is found to hold across a hierarchy of models spanning reduced-complexity and Earth-like global simulations and observations. Thus, the central pressure deficit is an intensity measure that combines maximum wind speed, storm size, and background rotation rate. This work has significant implications for both fundamental understanding and risk analysis, including why the central pressure better explains historical economic damages than does maximum wind speed.

Impulsive noise suppression in color images based on the geodesic digital paths

NASA Astrophysics Data System (ADS)

Smolka, Bogdan; Cyganek, Boguslaw

2015-02-01

In the paper a novel filtering design based on the concept of exploration of the pixel neighborhood by digital paths is presented. The paths start from the boundary of a filtering window and reach its center. The cost of transitions between adjacent pixels is defined in the hybrid spatial-color space. Then, an optimal path of minimum total cost, leading from pixels of the window's boundary to its center is determined. The cost of an optimal path serves as a degree of similarity of the central pixel to the samples from the local processing window. If a pixel is an outlier, then all the paths starting from the window's boundary will have high costs and the minimum one will also be high. The filter output is calculated as a weighted mean of the central pixel and an estimate constructed using the information on the minimum cost assigned to each image pixel. So, first the costs of optimal paths are used to build a smoothed image and in the second step the minimum cost of the central pixel is utilized for construction of the weights of a soft-switching scheme. The experiments performed on a set of standard color images, revealed that the efficiency of the proposed algorithm is superior to the state-of-the-art filtering techniques in terms of the objective restoration quality measures, especially for high noise contamination ratios. The proposed filter, due to its low computational complexity, can be applied for real time image denoising and also for the enhancement of video streams.

Different Relevance of Peripheral, Central or Nighttime Blood Pressure Measurements in the Prediction of Chronic Kidney Disease Progression in Patients with Mild or No-Proteinuria.

PubMed

Kuczera, Piotr; Kwiecień, Katarzyna; Adamczak, Marcin; Bączkowska, Teresa; Gozdowska, Jolanta; Madziarska, Katarzyna; Augustyniak-Bartosik, Hanna; Klinger, Marian; Durlik, Magdalena; Ritz, Eberhard; Wiecek, Andrzej

2018-05-10

Arterial hypertension is one of the leading factors aggravating the course of chronic kidney disease (CKD). It seems that the novel parameters used in the assessment of the blood pressure (BP) load (i.e. central blood pressure, nighttime blood pressure) may be more precise in predicting the cardiovascular risk and the progression of CKD in comparison with the traditional peripheral blood pressure measurements in the office conditions. The aim of the study was to assess the impact of the central, or nighttime blood pressure on the progression of CKD in patients with mild or no-proteinuria (autosomal, dominant polycystic kidney disease or IgA nephropathy). In each of the enrolled 46 patients with CKD stage 3 or 4, serum creatinine concentration was assessed, eGFR (MDRD) was calculated, also central blood pressure and pulse wave velocity (PWV) was assessed and the 24-hour ambulatory blood pressure monitoring (ABPM) was conducted at the beginning of the study and then repeated after one-year observation period. During the observation period mean eGFR decreased from 44.1 (33.2-50.6) mL/min to 36.7 (29.7-46.3) mL/min. No significant differences were observed in the peripheral blood pressure or central blood pressure parameters. After one-year observation period the values of diastolic blood pressure dipping during the night significantly decreased from 16 (13-19) mmHg to 12 (10-15) mmHg; p< 0.05. The values of systolic dipping during the night or the mean BP values recorded in ABPM did not change significantly. Additionally, no significant differences in the PWV values were found. In the multivariate regression model the change of serum creatinine concentration was explained by the initial diastolic dipping values. 1. In patients with CKD stages 3 or 4 and mild or no- proteinuria, peripheral and central blood pressure did not change significantly during a one-year observation period despite the significant decline of eGFR and seems not to participate in the CKD progression. 2. Reduced magnitude of the diastolic dipping, which reflects the increase of diastolic blood pressure load during the nighttime, may play an important role in the pathogenesis of deterioration of kidney function in these patients. © 2018 The Author(s). Published by S. Karger AG, Basel.

Melt density and the average composition of basalt

NASA Technical Reports Server (NTRS)

Stolper, E.; Walker, D.

1980-01-01

Densities of residual liquids produced by low pressure fractionation of olivine-rich melts pass through a minimum when pyroxene and plagioclase joint the crystallization sequence. The observation that erupted basalt compositions cluster around the degree of fractionation from picritic liquids corresponding to the density minimum in the liquid line of descent may thus suggest that the earth's crust imposes a density fiber on the liquids that pass through it, favoring the eruption of the light liquids at the density minimum over the eruption of denser more fractionated and less fractionated liquids.

Anisotropic patterns of liver cancer prevalence in Guangxi in Southwest China: is local climate a contributing factor?

PubMed

Deng, Wei; Long, Long; Tang, Xian-Yan; Huang, Tian-Ren; Li, Ji-Lin; Rong, Min-Hua; Li, Ke-Zhi; Liu, Hai-Zhou

2015-01-01

Geographic information system (GIS) technology has useful applications for epidemiology, enabling the detection of spatial patterns of disease dispersion and locating geographic areas at increased risk. In this study, we applied GIS technology to characterize the spatial pattern of mortality due to liver cancer in the autonomous region of Guangxi Zhuang in southwest China. A database with liver cancer mortality data for 1971-1973, 1990-1992, and 2004-2005, including geographic locations and climate conditions, was constructed, and the appropriate associations were investigated. It was found that the regions with the highest mortality rates were central Guangxi with Guigang City at the center, and southwest Guangxi centered in Fusui County. Regions with the lowest mortality rates were eastern Guangxi with Pingnan County at the center, and northern Guangxi centered in Sanjiang and Rongshui counties. Regarding climate conditions, in the 1990s the mortality rate of liver cancer positively correlated with average temperature and average minimum temperature, and negatively correlated with average precipitation. In 2004 through 2005, mortality due to liver cancer positively correlated with the average minimum temperature. Regions of high mortality had lower average humidity and higher average barometric pressure than did regions of low mortality. Our results provide information to benefit development of a regional liver cancer prevention program in Guangxi, and provide important information and a reference for exploring causes of liver cancer.

49 CFR 192.3 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... header or manifold. SMYS means specified minimum yield strength is: (1) For steel pipe manufactured in... the waters from the mean high water mark of the coast of the Gulf of Mexico and its inlets open to the... water. High-pressure distribution system means a distribution system in which the gas pressure in the...

49 CFR 192.3 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... header or manifold. SMYS means specified minimum yield strength is: (1) For steel pipe manufactured in... the waters from the mean high water mark of the coast of the Gulf of Mexico and its inlets open to the... water. High-pressure distribution system means a distribution system in which the gas pressure in the...

49 CFR 192.3 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... header or manifold. SMYS means specified minimum yield strength is: (1) For steel pipe manufactured in... the waters from the mean high water mark of the coast of the Gulf of Mexico and its inlets open to the... water. High-pressure distribution system means a distribution system in which the gas pressure in the...

49 CFR 192.3 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... header or manifold. SMYS means specified minimum yield strength is: (1) For steel pipe manufactured in... the waters from the mean high water mark of the coast of the Gulf of Mexico and its inlets open to the... water. High-pressure distribution system means a distribution system in which the gas pressure in the...

49 CFR 192.3 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... header or manifold. SMYS means specified minimum yield strength is: (1) For steel pipe manufactured in... the waters from the mean high water mark of the coast of the Gulf of Mexico and its inlets open to the... water. High-pressure distribution system means a distribution system in which the gas pressure in the...

49 CFR 195.306 - Test medium.

Code of Federal Regulations, 2011 CFR

2011-10-01

... this section, water must be used as the test medium. (b) Except for offshore pipelines, liquid... which produces a hoop stress of 50 percent of specified minimum yield strength; (3) The test section is... pressure is equal to or greater than a pressure that produces a hoop stress of 50 percent of specified...

46 CFR 153.370 - Minimum relief valve setting for ambient temperature cargo tanks.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 5 2014-10-01 2014-10-01 false Minimum relief valve setting for ambient temperature... temperature cargo tanks. The relief valve setting for a containment system that carries a cargo at ambient temperature must at least equal the cargo's vapor pressure at 46 °C (approx. 115 °F). [CGD 81-078, 50 FR 21173...

46 CFR 153.370 - Minimum relief valve setting for ambient temperature cargo tanks.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 5 2013-10-01 2013-10-01 false Minimum relief valve setting for ambient temperature... temperature cargo tanks. The relief valve setting for a containment system that carries a cargo at ambient temperature must at least equal the cargo's vapor pressure at 46 °C (approx. 115 °F). [CGD 81-078, 50 FR 21173...

46 CFR 153.370 - Minimum relief valve setting for ambient temperature cargo tanks.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 5 2012-10-01 2012-10-01 false Minimum relief valve setting for ambient temperature... temperature cargo tanks. The relief valve setting for a containment system that carries a cargo at ambient temperature must at least equal the cargo's vapor pressure at 46 °C (approx. 115 °F). [CGD 81-078, 50 FR 21173...

46 CFR 153.370 - Minimum relief valve setting for ambient temperature cargo tanks.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Minimum relief valve setting for ambient temperature... temperature cargo tanks. The relief valve setting for a containment system that carries a cargo at ambient temperature must at least equal the cargo's vapor pressure at 46 °C (approx. 115 °F). [CGD 81-078, 50 FR 21173...

46 CFR 153.370 - Minimum relief valve setting for ambient temperature cargo tanks.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 5 2011-10-01 2011-10-01 false Minimum relief valve setting for ambient temperature... temperature cargo tanks. The relief valve setting for a containment system that carries a cargo at ambient temperature must at least equal the cargo's vapor pressure at 46 °C (approx. 115 °F). [CGD 81-078, 50 FR 21173...

40 CFR Table 3 to Subpart Hhh of... - Operating Parameters To Be Monitored and Minimum Measurement and Recording Frequencies

Code of Federal Regulations, 2011 CFR

2011-07-01

... rural HMIWI HMIWI a with dry scrubber followed by fabric filter HMIWI a with wet scrubber HMIWI a with dry scrubber followed by fabric filter and wet scrubber Maximum operating parameters: Maximum charge... mercury (Hg) sorbent flow rate Hourly Once per hour ✔ ✔ Minimum pressure drop across the wet scrubber or...

Assessment of corneal epithelial thickness in dry eye patients.

PubMed

Cui, Xinhan; Hong, Jiaxu; Wang, Fei; Deng, Sophie X; Yang, Yujing; Zhu, Xiaoyu; Wu, Dan; Zhao, Yujin; Xu, Jianjiang

2014-12-01

To investigate the features of corneal epithelial thickness topography with Fourier-domain optical coherence tomography (OCT) in dry eye patients. In this cross-sectional study, 100 symptomatic dry eye patients and 35 normal subjects were enrolled. All participants answered the ocular surface disease index questionnaire and were subjected to OCT, corneal fluorescein staining, tear breakup time, Schirmer 1 test without anesthetic (S1t), and meibomian morphology. Several epithelium statistics for each eye, including central, superior, inferior, minimum, maximum, minimum - maximum, and map standard deviation, were averaged. Correlations of epithelial thickness with the symptoms of dry eye were calculated. The mean (±SD) central, superior, and inferior corneal epithelial thickness was 53.57 (±3.31) μm, 52.00 (±3.39) μm, and 53.03 (±3.67) μm in normal eyes and 52.71 (±2.83) μm, 50.58 (±3.44) μm, and 52.53 (±3.36) μm in dry eyes, respectively. The superior corneal epithelium was thinner in dry eye patients compared with normal subjects (p = 0.037), whereas central and inferior epithelium were not statistically different. In the dry eye group, patients with higher severity grades had thinner superior (p = 0.017) and minimum (p < 0.001) epithelial thickness, more wide range (p = 0.032), and greater deviation (p = 0.003). The average central epithelial thickness had no correlation with tear breakup time, S1t, or the severity of meibomian glands, whereas average superior epithelial thickness positively correlated with S1t (r = 0.238, p = 0.017). Fourier-domain OCT demonstrated that the thickness map of the dry eye corneal epithelium was thinner than normal eyes in the superior region. In more severe dry eye disease patients, the superior and minimum epithelium was much thinner, with a greater range of map standard deviation.

Generating a Simulated Fluid Flow Over an Aircraft Surface Using Anisotropic Diffusion

NASA Technical Reports Server (NTRS)

Rodriguez, David L. (Inventor); Sturdza, Peter (Inventor)

2013-01-01

A fluid-flow simulation over a computer-generated aircraft surface is generated using a diffusion technique. The surface is comprised of a surface mesh of polygons. A boundary-layer fluid property is obtained for a subset of the polygons of the surface mesh. A pressure-gradient vector is determined for a selected polygon, the selected polygon belonging to the surface mesh but not one of the subset of polygons. A maximum and minimum diffusion rate is determined along directions determined using a pressure gradient vector corresponding to the selected polygon. A diffusion-path vector is defined between a point in the selected polygon and a neighboring point in a neighboring polygon. An updated fluid property is determined for the selected polygon using a variable diffusion rate, the variable diffusion rate based on the minimum diffusion rate, maximum diffusion rate, and angular difference between the diffusion-path vector and the pressure-gradient vector.

Variation of the pressure limits of flame propagation with tube diameter for propane-air mixtures

NASA Technical Reports Server (NTRS)

Belles, Frank E; Simon, Dorothy M

1951-01-01

An investigation was made of the variation of the pressure limits of flame propagation with tube diameter for quiescent propane with tube diameter for quiescent propane-air mixtures. Pressure limits were measured in glass tubes of six different inside diameters, with a precise apparatus. Critical diameters for flame propagation were calculated and the effect of pressure was determined. The critical diameters depended on the pressure to the -0.97 power for stoichiometric mixtures. The pressure dependence decreased with decreasing propane concentration. Critical diameters were related to quenching distance, flame speeds, and minimum ignition energy.

Which Measurement of Blood Pressure Is More Associated With Albuminuria in Patients With Type 2 Diabetes: Central Blood Pressure or Peripheral Blood Pressure?

PubMed

Kitagawa, Noriyuki; Okada, Hiroshi; Tanaka, Muhei; Hashimoto, Yoshitaka; Kimura, Toshihiro; Nakano, Koji; Yamazaki, Masahiro; Hasegawa, Goji; Nakamura, Naoto; Fukui, Michiaki

2016-08-01

The aim of this study was to investigate whether central systolic blood pressure (SBP) was associated with albuminuria, defined as urinary albumin excretion (UAE) ≥30 mg/g creatinine, and, if so, whether the relationship of central SBP with albuminuria was stronger than that of peripheral SBP in patients with type 2 diabetes. The authors performed a cross-sectional study in 294 outpatients with type 2 diabetes. The relationship between peripheral SBP or central SBP and UAE using regression analysis was evaluated, and the odds ratios of peripheral SBP or central SBP were calculated to identify albuminuria using logistic regression model. Moreover, the area under the receiver operating characteristic curve (AUC) of central SBP was compared with that of peripheral SBP to identify albuminuria. Multiple regression analysis demonstrated that peripheral SBP (β=0.255, P<.0001) or central SBP (r=0.227, P<.0001) was associated with UAE. Multiple logistic regression analysis demonstrated that peripheral SBP (odds ratio, 1.029; 95% confidence interval, 1.016-1.043) or central SBP (odds ratio, 1.022; 95% confidence interval, 1.011-1.034) was associated with an increased odds of albuminuria. In addition, AUC of peripheral SBP was significantly greater than that of central SBP to identify albuminuria (P=0.035). Peripheral SBP is superior to central SBP in identifying albuminuria, although both peripheral and central SBP are associated with UAE in patients with type 2 diabetes. © 2016 Wiley Periodicals, Inc.

Decreased cardiopulmonary baroreflex sensitivity in Chagas' heart disease.

PubMed

Consolim-Colombo, F M; Filho, J A; Lopes, H F; Sobrinho, C R; Otto, M E; Riccio, G M; Mady, C; Krieger, E M

2000-12-01

No study has been performed on reflexes originating from receptors in the heart that might be involved in the pathological lesions of Chagas' heart disease. Our study was undertaken to analyze the role of cardiopulmonary reflex on cardiovascular control in Chagas' disease. We studied 14 patients with Chagas' disease without heart failure and 12 healthy matched volunteers. Central venous pressure, arterial blood pressure, heart rate, forearm blood flow, and forearm vascular resistance were recorded during deactivation of cardiopulmonary receptors. By reducing central venous pressure by applying -10 and -15 mm Hg of negative pressure to the lower body, we observed (a) a similar decrease of central venous pressure in both groups; (b) a marked increase in forearm vascular resistance in the control group but a blunted increase in the Chagas' group; and (c) no significant changes in blood pressure and heart rate. To analyze cardiopulmonary and arterial receptors, we applied -40 mm Hg of lower-body negative pressure. As a consequence, (a) central venous pressure decreased similarly in both groups; (b) blood pressure was maintained in the control group, whereas in patients with Chagas' disease, a decrease in systolic and mean arterial pressure occurred; (c) heart rate increased in both groups; and (d) forearm vascular resistance increased significantly and similarly in both groups. Unloading of receptors with low levels of lower-body negative pressure did not increase forearm vascular resistance in patients with Chagas' disease, which suggests that the reflex mediated by cardiopulmonary receptors is impaired in patients with Chagas' disease without heart failure. Overall control of circulation appears to be compromised because patients did not maintain blood pressure under high levels of lower-body negative pressure.

Structure of a swirling jet with vortex breakdown and combustion

NASA Astrophysics Data System (ADS)

Sharaborin, D. K.; Dulin, V. M.; Markovich, D. M.

2018-03-01

An experimental investigation is performed in order to compare the time-averaged spatial structure of low- and high-swirl turbulent premixed lean flames by using the particle image velocimetry and spontaneous Raman scattering techniques. Distributions of the time-average velocity, density and concentration of the main components of the gas mixture are measured for turbulent premixed swirling propane/air flames at atmospheric pressure for the equivalence ratio Φ = 0.7 and Reynolds number Re = 5000 for low- and high-swirl reacting jets. For the low-swirl jet (S = 0.41), the local minimum of the axial mean velocity is observed within the jet center. The positive value of the mean axial velocity indicates the absence of a permanent recirculation zone, and no clear vortex breakdown could be determined from the average velocity field. For the high-swirl jet (S = 1.0), a pronounced vortex breakdown took place with a bubble-type central recirculation zone. In both cases, the flames are stabilized in the inner mixing layer of the jet around the central wake, containing hot combustion products. O2 and CO2 concentrations in the wake of the low-swirl jet are found to be approximately two times smaller and greater than those in the recirculation zone of the high-swirl jet, respectively.

Directly measured cabin pressure conditions during Boeing 747-400 commercial aircraft flights.

PubMed

Kelly, Paul T; Seccombe, Leigh M; Rogers, Peter G; Peters, Matthew J

2007-07-01

In the low pressure environment of commercial aircraft, hypoxaemia may be common and accentuated in patients with lung or heart disease. Regulations specify a cabin pressure not lower than 750 hPa but it is not known whether this standard is met. This knowledge is important in determining the hazards of commercial flight for patients and the validity of current flight simulation tests. Using a wrist-watch recording altimeter, cabin pressure was recorded at 60 s intervals on 45 flights in Boeing 747-400 aircraft with three airlines. A log was kept of aircraft altitude using the in-flight display. Change in cabin pressure during flight, relationship between aircraft altitude and cabin pressure and proportion of flight time with cabin pressure approaching the minimum specified by regulation were determined. Flight duration averaged 10 h. Average cabin pressure during flight was 846 hPa. There was a linear fall in cabin pressure as the aircraft cruising altitude increased. At 10,300 m (34,000 ft) cabin pressure was 843 hPa and changed 8 hPa for every 300 m (1000 ft) change in aircraft altitude (r(2) = 0.993; P < 0.001). Lowest cabin pressure was 792 hPa at 12 200 m (40,000 ft) but during only 2% of flight time was cabin pressure less than 800 hPa. Cabin pressure is determined only by the engineering of the aircraft and its altitude and in the present study was always higher than required by regulation. Current fitness-to-fly evaluations simulate cabin conditions that passengers will not experience on these aircraft. There may be increased risks to patients should new or older aircraft operate nearer to the present minimum standard.

Relation between Pressure Balance Structures and Polar Plumes from Ulysses High Latitude Observations

NASA Technical Reports Server (NTRS)

Yamauchi, Yohei; Suess, Steven T.; Sakurai, Takashi

2002-01-01

Ulysses observations have shown that pressure balance structures (PBSs) are a common feature in high-latitude, fast solar wind near solar minimum. Previous studies of Ulysses/SWOOPS plasma data suggest these PBSs may be remnants of coronal polar plumes. Here we find support for this suggestion in an analysis of PBS magnetic structure. We used Ulysses magnetometer data and applied a minimum variance analysis to magnetic discontinuities in PBSs. We found that PBSs preferentially contain tangential discontinuities, as opposed to rotational discontinuities and to non-PBS regions in the solar wind. This suggests that PBSs contain structures like current sheets or plasmoids that may be associated with network activity at the base of plumes.

Relation Between Pressure Balance Structures and Polar Plumes from Ulysses High Latitude Observations

NASA Technical Reports Server (NTRS)

Yamauchi, Y.; Suess, Steven T.; Sakurai, T.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

Ulysses observations have shown that pressure balance structures (PBSs) are a common feature in high-latitude, fast solar wind near solar minimum. Previous studies of Ulysses/SWOOPS plasma data suggest these PBSs may be remnants of coronal polar plumes. Here we find support for this suggestion in an analysis of PBS magnetic structure. We used Ulysses magnetometer data and applied a minimum variance analysis to discontinuities. We found that PBSs preferentially contain tangential discontinuities, as opposed to rotational discontinuities and to non-PBS regions in the solar wind. This suggests that PBSs contain structures like current sheets or plasmoids that may be associated with network activity at the base of plumes.

Optimal Design and Operation of Permanent Irrigation Systems

NASA Astrophysics Data System (ADS)

Oron, Gideon; Walker, Wynn R.

1981-01-01

Solid-set pressurized irrigation system design and operation are studied with optimization techniques to determine the minimum cost distribution system. The principle of the analysis is to divide the irrigation system into subunits in such a manner that the trade-offs among energy, piping, and equipment costs are selected at the minimum cost point. The optimization procedure involves a nonlinear, mixed integer approach capable of achieving a variety of optimal solutions leading to significant conclusions with regard to the design and operation of the system. Factors investigated include field geometry, the effect of the pressure head, consumptive use rates, a smaller flow rate in the pipe system, and outlet (sprinkler or emitter) discharge.

Low-Pressure Capability of NASA Glenn's 10- by 10-Foot Supersonic Wind Tunnel Expanded

NASA Technical Reports Server (NTRS)

Roeder, James W.

2004-01-01

Extremely low dynamic pressure Q conditions are desired for space-related research including the testing of parachute designs and other decelerator concepts for future vehicles landing on Mars. Therefore, the low-pressure operating capability of the Abe Silverstein 10- by 10-foot Supersonic Wind Tunnel (10 10 SWT) at NASA Glenn Research Center was recently increased. Successful checkout tests performed in the fall of 2002 showed significantly reduced minimum operating pressures in the wind tunnel.

Household air pollution and measures of blood pressure, arterial stiffness and central haemodynamics.

PubMed

Baumgartner, Jill; Carter, Ellison; Schauer, James J; Ezzati, Majid; Daskalopoulou, Stella S; Valois, Marie-France; Shan, Ming; Yang, Xudong

2018-02-09

We evaluated the exposure-response associations between personal exposure to air pollution from biomass stoves and multiple vascular and haemodynamic parameters in rural Chinese women. We analysed the baseline information from a longitudinal study in southwestern China. Women's brachial and central blood pressure and pulse pressure, carotid-femoral pulse wave velocity and augmentation index, and their 48-hour personal exposures to fine particulate matter (PM 2.5 ) and black carbon were measured in summer and winter. We evaluated the associations between exposure to air pollution and haemodynamic parameters using mixed-effects regression models adjusted for known cardiovascular risk factors. Women's (n=205, ages 27-86 years) exposures to PM 2.5 and black carbon ranged from 14 µg/m 3 to 1405 µg/m 3 and 0.1-121.8 µg/m 3 , respectively. Among women aged ≥50 years, increased PM 2.5 exposure was associated with higher systolic (brachial: 3.5 mm Hg (P=0.05); central: 4.4 mm Hg (P=0.005)) and diastolic blood pressure (central: 1.3 mm Hg (P=0.10)), higher pulse pressure (peripheral: 2.5 mm Hg (P=0.05); central: 2.9 mm Hg (P=0.008)) and lower peripheral-central pulse pressure amplification (-0.007 (P=0.04)). Among younger women, the associations were inconsistent in the direction of effect and not statistically significant. Increased PM 2.5 exposure was associated with no difference in pulse wave velocity and modestly higher augmentation index though the CI included zero (1.1%; 95% CI -0.2% to 2.4%). Similar associations were found for black carbon exposure. Exposure to household air pollution was associated with higher blood pressure and central haemodynamics in older Chinese women, with no associations observed with pulse wave velocity. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Sustained reduction in blood pressure from electrical activation of the baroreflex is mediated via the central pathway of unmyelinated baroreceptors.

PubMed

Turner, Michael J; Kawada, Toru; Shimizu, Shuji; Sugimachi, Masaru

2014-06-13

This study aims to identify the contribution of myelinated (A-fiber) and unmyelinated (C-fiber) baroreceptor central pathways to the baroreflex control of sympathetic nerve activity and arterial pressure. Two binary white noise stimulation protocols were used to electrically stimulate the aortic depressor nerve and activate reflex responses from either A-fiber (3 V, 20-100 Hz) or C-fiber (20 V, 0-10 Hz) baroreceptor in anesthetized Sprague-Dawley rats (n=10). Transfer function analysis was performed between stimulation and sympathetic nerve activity (central arc), sympathetic nerve activity and arterial pressure (peripheral arc), and stimulation and arterial pressure (Stim-AP arc). The central arc transfer function from nerve stimulation to splanchnic sympathetic nerve activity displayed derivative characteristics for both stimulation protocols. However, the modeled steady-state gain (0.28 ± 0.04 vs. 4.01 ± 0.2%·Hz(-1), P<0.001) and coherence at 0.01 Hz (0.44 ± 0.05 vs. 0.81 ± 0.03, P<0.05) were significantly lower for A-fiber stimulation compared with C-fiber stimulation. The slope of the dynamic gain was higher for A-fiber stimulation (14.82 ± 1.02 vs. 7.21 ± 0.79 dB·decade(-1), P<0.001). The steady-state gain of the Stim-AP arc was also significantly lower for A-fiber stimulation compared with C-fiber stimulation (0.23 ± 0.05 vs. 3.05 ± 0.31 mmHg·Hz(-1), P<0.001). These data indicate that the A-fiber central pathway contributes to high frequency arterial pressure regulation and the C-fiber central pathway provides more sustained changes in sympathetic nerve activity and arterial pressure. A sustained reduction in arterial pressure from electrical stimulation of arterial baroreceptor afferents is likely mediated through the C-fiber central pathway. Copyright © 2014 Elsevier Inc. All rights reserved.

Analysis of starvation effects on hydrodynamic lubrication in nonconforming contacts

NASA Technical Reports Server (NTRS)

Brewe, D. E.; Hamrock, B. J.

1981-01-01

The effects of lubricant starvation on minimum film thickness, under conditions of a hydrodynamic point contact, are determined by numerical methods where: (1) starvation is effected by varying the fluid inlet level; (2) the Reynolds boundary conditions are applied at the cavitation boundary; and (3) zero pressure is stipulated at the meniscus or inlet boundary. Seventy-four cases were used to numerically determine a minimum-film-thickness equation, as a function of the ratio of dimensionless load to dimensionless speed for varying degrees of starvation. A film reduction factor was in turn determined as a function of the fluid inlet level, and a starved, fully-flooded boundary was defined along with an expression determining the onset of starvation. It is found that as the degree of starvation increases, the minimum film thickness decreases gradually until the fluid inlet becomes critical. The changes in the inlet pressure buildup due to changing the available lubricant supply are presented in the form of three-dimensional isometric plots.

Axisymmetric inlet minimum weight design method

NASA Technical Reports Server (NTRS)

Nadell, Shari-Beth

1995-01-01

An analytical method for determining the minimum weight design of an axisymmetric supersonic inlet has been developed. The goal of this method development project was to improve the ability to predict the weight of high-speed inlets in conceptual and preliminary design. The initial model was developed using information that was available from inlet conceptual design tools (e.g., the inlet internal and external geometries and pressure distributions). Stiffened shell construction was assumed. Mass properties were computed by analyzing a parametric cubic curve representation of the inlet geometry. Design loads and stresses were developed at analysis stations along the length of the inlet. The equivalent minimum structural thicknesses for both shell and frame structures required to support the maximum loads produced by various load conditions were then determined. Preliminary results indicated that inlet hammershock pressures produced the critical design load condition for a significant portion of the inlet. By improving the accuracy of inlet weight predictions, the method will improve the fidelity of propulsion and vehicle design studies and increase the accuracy of weight versus cost studies.

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

PubMed

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.

PHENIX results on open heavy flavor production

NASA Astrophysics Data System (ADS)

Hachiya, Takashi

2018-02-01

PHENIX measures the open heavy flavor productions in p + p, Cu+Au, and Au+Au collisions at = 200 and 510 GeV using the silicon tracking detectors for mid- and forward rapidities. In Au+Au collisions, the nuclear modification of single electrons from bottom and charm hadron decays are measured for minimum bias and most central collisions. It is found that bottoms are less suppressed than charms in pT=3-5 GeV/c and charms in most central collisions are more suppressed than that in minimum bias collisions. In p + p and Cu+Au collisions, J/ψ from B meson decays are measured at forward and backward rapidities. The nuclear modification of B mesons in Cu+Au collisions is consistent with unity.

The effect of ignition location on explosion venting of hydrogen-air mixtures

NASA Astrophysics Data System (ADS)

Cao, Y.; Guo, J.; Hu, K.; Xie, L.; Li, B.

2017-07-01

The effect of ignition location and vent burst pressure on the internal pressure-time history and external flame propagation was investigated for vented explosions of hydrogen-air mixtures in a small cylindrical vessel. A high-speed camera was used to record videos of the external flame while pressure transducers were used to record pressure-time histories. It was found that central ignition always leads to the maximum internal peak overpressure, and front ignition resulted in the lowest value of internal peak overpressure. The internal peak overpressures are increased corresponding to the increase in the vent burst pressure in the cases of central and rear ignition. Because of the effect of acoustic oscillations, the phenomenon of oscillations is observed in the internal pressure profile for the case of front ignition. The pressure oscillations for the cases of rear and central ignition are triggered by external explosions. The behavior of flames outside the chamber is significantly associated with the internal pressure of the chamber so that the velocity of the jet flame is closely related to the internal overpressure peak.

Pressure ulcer and patient characteristics--A point prevalence study in a tertiary hospital of India based on the European Pressure Ulcer Advisory Panel minimum data set.

PubMed

Mehta, Chitra; George, Joby V; Mehta, Yatin; Wangmo, Namgyal

2015-08-01

Pressure ulcers is a frequent problem in hospitalized patients. Several prevalence studies have been conducted across the globe. Little information is available regarding prevalence of pressure ulcers in India. The aim was to identify the prevalence of pressure ulcers in one of the tertiary hospital in northern India and the factors associated with its development. A cross sectional point prevalence study. European Pressure Ulcer Advisory Panel (EPUAP) data collection form. Ethics approval was obtained prior to start of the study. Total of 358 patients were enrolled in the study. All patients above 18 years of age admitted in intensive care units and wards were included in the study. Patients admitted in emergency, day care, coronary care unit were excluded because of their short duration of hospital stay (varies from 24 to 72 h usually). All patients admitted before midnight on the predetermined day were included. The Braden scale was used to identify the risk of developing pressure ulcers. European Pressure ulcer advisory panel (EPUAP) minimum data set was used to collect prevalence data. The overall prevalence rate was 7.8%.The sacrum and heel were more commonly affected. Grade III pressure ulcers were the most common (42.8%). The pressure ulcer prevalence rate in our hospital was lower than that published in international studies. Severe forms of pressure ulcers were commonly encountered This data provides background information that may help us in developing protocols for applying effective practices for prevention of pressure ulcers. Copyright © 2015 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

Improving the Traceability of Meteorological Measurements at Automatic Weather Stations in Thailand

NASA Astrophysics Data System (ADS)

Keawprasert, T.; Sinhaneti, T.; Phuuntharo, P.; Phanakulwijit, S.; Nimsamer, A.

2017-08-01

A joint project between the National Institute of Metrology Thailand (NIMT) and the Thai Meteorology Department (TMD) was established for improving the traceability of meteorology measurements at automatic weather stations (AWSs) in Thailand. The project aimed to improve traceability of air temperature, relative humidity and atmospheric pressure by implementing on-site calibration facilities and developing of new calibration procedures. First, new portable calibration facilities for air temperature, humidity and pressure were set up as working standard of the TMD. A portable humidity calibrator was applied as a uniform and stable source for calibration of thermo-hygrometers. A dew-point hygrometer was employed as reference hygrometer and a platinum resistance thermometer (PRT) traceable to NIMT was used as reference thermometer. The uniformity and stability in both temperature and relative humidity were characterized at NIMT. A transportable pressure calibrator was used for calibration of air pressure sensor. The estimate overall uncertainty of the calibration setup is 0.2 K for air temperature, 1.0 % for relative humidity and 0.2 hPa for atmospheric pressure, respectively. Second, on-site calibration procedures were developed and four AWSs in the central part and the northern of Thailand were chosen as pilot stations for on-site calibration using the new calibration setups and developed calibration procedures. At each station, the calibration was done at the minimum temperature, average temperature and maximum temperature of the year, for air temperature, 20 %, 55 % and 90 % for relative humidity at the average air temperature of that station and at a one-year statistics pressure range for atmospheric pressure at ambient temperature. Additional in-field uncertainty contributions such as the temperature dependence on relative humidity measurement were evaluated and included in the overall uncertainty budget. Preliminary calibration results showed that using a separate PRT probe at these AWSs would be recommended for improving the accuracy of air temperature measurement. In case of relative humidity measurement, the data logger software is needed to be upgraded for achieving higher accuracy of less than 3 %. For atmospheric pressure measurement, a higher accuracy barometer traceable to NIMT could be used to reduce the calibration uncertainty to below 0.2 hPa.

The antigravity suit in neurosurgery. Cardiovascular responses in seated neurosurgical patients.

PubMed

Brodrick, P M; Ingram, G S

1988-09-01

The haemodynamic responses associated with inflation of the antigravity suit (G suit, aviation type) to 8.0 kPa were studied in a series of 40 patients who underwent neurosurgical operations in the sitting position. The study showed statistically significant increases in systolic arterial pressure (p less than 0.005) and mean central venous pressure (p less than 0.001) with inflation of the suit. The systolic arterial and mean central venous pressures remained significantly elevated immediately before deflation of the suit at the end of the operation (p less than 0.001 and p less than 0.005 respectively). The addition of 0.8-1.0 kPa positive end expiratory pressure during suit inflation was also investigated. A further increase in central venous pressure occurred but this did not achieve statistical significance.

40 CFR Table 3 to Subpart Ddddd of... - Operating Limits for Boilers and Process Heaters With Mercury Emission Limits and Boilers and...

Code of Federal Regulations, 2010 CFR

2010-07-01

... minimum pressure drop and liquid flow-rate at or above the operating levels established during the... leak detection system alarm does not sound more than 5 percent of the operating time during a 6-month... control Maintain the minimum sorbent or carbon injection rate at or above the operating levels established...

40 CFR Table 3 to Subpart Ddddd of... - Operating Limits for Boilers and Process Heaters With Mercury Emission Limits and Boilers and...

Code of Federal Regulations, 2011 CFR

2011-07-01

... minimum pressure drop and liquid flow-rate at or above the operating levels established during the... leak detection system alarm does not sound more than 5 percent of the operating time during a 6-month... control Maintain the minimum sorbent or carbon injection rate at or above the operating levels established...

An Analysis of Minimum Service Standards (MSS) in Basic Education: A Case Study at Magelang Municipality, Central Java, Indonesia

ERIC Educational Resources Information Center

Haryati, Sri

2014-01-01

The study aims at analyzing the achievement of Minimum Service Standards (MSS) in Basic Education through a case study at Magelang Municipality. The findings shall be used as a starting point to predict the needs to meet MMS by 2015 and to provide strategies for achievement. Both primary and secondary data were used in the study investigating the…

Numerical design and optimization of hydraulic resistance and wall shear stress inside pressure-driven microfluidic networks.

PubMed

Damiri, Hazem Salim; Bardaweel, Hamzeh Khalid

2015-11-07

Microfluidic networks represent the milestone of microfluidic devices. Recent advancements in microfluidic technologies mandate complex designs where both hydraulic resistance and pressure drop across the microfluidic network are minimized, while wall shear stress is precisely mapped throughout the network. In this work, a combination of theoretical and modeling techniques is used to construct a microfluidic network that operates under minimum hydraulic resistance and minimum pressure drop while constraining wall shear stress throughout the network. The results show that in order to minimize the hydraulic resistance and pressure drop throughout the network while maintaining constant wall shear stress throughout the network, geometric and shape conditions related to the compactness and aspect ratio of the parent and daughter branches must be followed. Also, results suggest that while a "local" minimum hydraulic resistance can be achieved for a geometry with an arbitrary aspect ratio, a "global" minimum hydraulic resistance occurs only when the aspect ratio of that geometry is set to unity. Thus, it is concluded that square and equilateral triangular cross-sectional area microfluidic networks have the least resistance compared to all rectangular and isosceles triangular cross-sectional microfluidic networks, respectively. Precise control over wall shear stress through the bifurcations of the microfluidic network is demonstrated in this work. Three multi-generation microfluidic network designs are considered. In these three designs, wall shear stress in the microfluidic network is successfully kept constant, increased in the daughter-branch direction, or decreased in the daughter-branch direction, respectively. For the multi-generation microfluidic network with constant wall shear stress, the design guidelines presented in this work result in identical profiles of wall shear stresses not only within a single generation but also through all the generations of the microfluidic network under investigation. The results obtained in this work are consistent with previously reported data and suitable for a wide range of lab-on-chip applications.

33 CFR Appendix A to Part 154 - Guidelines for Detonation Flame Arresters

Code of Federal Regulations, 2010 CFR

2010-07-01

... (CG-522). 1. Scope 1.1This standard provides the minimum requirements for design, construction.../Circ. 373/Rev. 1—Revised Standards for the Design, Testing and Locating of Devices to Prevent the... maximum design pressure drop for that maximum flow rate. 6.1.10Maximum operating pressure. 7. Materials 7...

Flight Demonstration of a Shock Location Sensor Using Constant Voltage Hot-Film Anemometry

NASA Technical Reports Server (NTRS)

Moes, Timothy R.; Sarma, Garimella R.; Mangalam, Siva M.

1997-01-01

Flight tests have demonstrated the effectiveness of an array of hot-film sensors using constant voltage anemometry to determine shock position on a wing or aircraft surface at transonic speeds. Flights were conducted at the NASA Dryden Flight Research Center using the F-15B aircraft and Flight Test Fixture (FTF). A modified NACA 0021 airfoil was attached to the side of the FTF, and its upper surface was instrumented to correlate shock position with pressure and hot-film sensors. In the vicinity of the shock-induced pressure rise, test results consistently showed the presence of a minimum voltage in the hot-film anemometer outputs. Comparing these results with previous investigations indicate that hot-film anemometry can identify the location of the shock-induced boundary layer separation. The flow separation occurred slightly forward of the shock- induced pressure rise for a laminar boundary layer and slightly aft of the start of the pressure rise when the boundary layer was tripped near the airfoil leading edge. Both minimum mean output and phase reversal analyses were used to identify the shock location.

Performance Charts for a Turbojet System

NASA Technical Reports Server (NTRS)

Karp, Irving M.

1947-01-01

Convenient charts are presented for computing the thrust, fuel consumption, and other performance values of a turbojet system. These charts take into account the effects of ram pressure, compressor pressure ratio, ratio of combustion-chamber-outlet temperature to atmospheric temperature, compressor efficiency, turbine efficiency, combustion efficiency, discharge-nozzle coefficient, losses in total pressure in the inlet to the jet-propulsion unit and in the combustion chamber, and variation in specific heats with temperature. The principal performance charts show clearly the effects of the primary variables and correction charts provide the effects of the secondary variables. The performance of illustrative cases of turbojet systems is given. It is shown that maximum thrust per unit mass rate of air flow occurs at a lower compressor pressure ratio than minimum specific fuel consumption. The thrust per unit mass rate of air flow increases as the combustion-chamber discharge temperature increases. For minimum specific fuel consumption, however, an optimum combustion-chamber discharge temperature exists, which in some cases may be less than the limiting temperature imposed by the strength temperature characteristics of present materials.

Characteristics of Precipitation Features and Annual Rainfall during the TRMM Era in the Central Andes

NASA Technical Reports Server (NTRS)

Mohr, Karen I.; Slayback, Daniel; Yager, Karina

2014-01-01

The central Andes extends from 7 deg to 21 deg S, with its eastern boundary defined by elevation (1000m and greater) and its western boundary by the coastline. The authors used a combination of surface observations, reanalysis, and the University of Utah Tropical Rainfall Measuring Mission (TRMM) precipitation features (PF) database to understand the characteristics of convective systems and associated rainfall in the central Andes during the TRMM era, 1998-2012. Compared to other dry (West Africa), mountainous (Himalayas), and dynamically linked (Amazon) regions in the tropics, the central Andes PF population was distinct from these other regions, with small and weak PFs dominating its cumulative distribution functions and annual rainfall totals. No more than 10% of PFs in the central Andes met any of the thresholds used to identify and define deep convection (minimum IR cloud-top temperatures, minimum 85-GHz brightness temperature, maximum height of the 40-dBZ echo). For most of the PFs, available moisture was limited (less than 35mm) and instability low (less than 500 J kg(exp -1)). The central Andes represents a largely stable, dry to arid environment, limiting system development and organization. Hence, primarily short-duration events (less than 60 min) characterized by shallow convection and light to light-moderate rainfall rates (0.5-4.0 mm h(exp -1)) were found.

Doppler indexes of left ventricular systolic and diastolic flow and central pulse pressure in relation to renal resistive index.

PubMed

Kuznetsova, Tatiana; Cauwenberghs, Nicholas; Knez, Judita; Thijs, Lutgarde; Liu, Yan-Ping; Gu, Yu-Mei; Staessen, Jan A

2015-04-01

The cardio-renal interaction occurs via hemodynamic and humoral factors. Noninvasive assessment of renal hemodynamics is currently possible by assessment of renal resistive index (RRI) derived from intrarenal Doppler arterial waveforms as ((peak systolic velocity - end-diastolic velocity)/peak systolic velocity). Limited information is available regarding the relationship between RRI and cardiac hemodynamics. We investigated these associations in randomly recruited subjects from a general population. In 171 participants (48.5% women; mean age, 52.2 years), using pulsed wave Doppler, we measured RRI (mean, 0.60) and left ventricular outflow tract (LVOT) and transmitral (E and A) blood flow peak velocities and its velocity time integrals (VTI). Using carotid applanation tonometry, we measured central pulse pressure and arterial stiffness indexes such as augmentation pressure and carotid-femoral pulse wave velocity. In stepwise regression analysis, RRI independently and significantly increased with female sex, age, body weight, brachial pulse pressure, and use of β-blockers, whereas it decreased with body height and mean arterial pressure. In multivariable-adjusted models with central pulse pressure and arterial stiffness indexes as the explanatory variables, we observed a significant and positive correlation of RRI only with central pulse pressure (P < 0.0001). Among the Doppler indexes of left ventricular blood flow, RRI was significantly and positively associated with LVOT and E peak velocities (P ≤ 0.012) and VTIs (P ≤ 0.010). We demonstrated that in unselected subjects RRI was significantly associated with central pulse pressure and left ventricular systolic and diastolic Doppler blood flow indexes. Our findings imply that in addition to the anthropometric characteristics, cardiac hemodynamic factors influence the intrarenal arterial Doppler waveform patterns. © American Journal of Hypertension, Ltd 2014. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Water cooled static pressure probe

NASA Technical Reports Server (NTRS)

Lagen, Nicholas T. (Inventor); Eves, John W. (Inventor); Reece, Garland D. (Inventor); Geissinger, Steve L. (Inventor)

1991-01-01

An improved static pressure probe containing a water cooling mechanism is disclosed. This probe has a hollow interior containing a central coolant tube and multiple individual pressure measurement tubes connected to holes placed on the exterior. Coolant from the central tube symmetrically immerses the interior of the probe, allowing it to sustain high temperature (in the region of 2500 F) supersonic jet flow indefinitely, while still recording accurate pressure data. The coolant exits the probe body by way of a reservoir attached to the aft of the probe. The pressure measurement tubes are joined to a single, larger manifold in the reservoir. This manifold is attached to a pressure transducer that records the average static pressure.

Circulatory failure during severe hyperthermia in dog.

PubMed

Miki, K; Morimoto, T; Nose, H; Itoh, T; Yamada, S

1983-01-01

The effect of acute hyperthermia on circulatory function was studied in 6 mongrel dogs. At a core temperature of about 40 degrees C, central venous pressure and stroke volume were maintained at almost normal level. Cardiac output significantly increased (26 ml/(kg . min)) while systemic vascular resistance significantly decreased (1.2 mmHg . sec/ml). In addition, significant decrease in vascular compliance by 40% was observed. When body temperature was raised further (severe hyperthermia), an abrupt fall of arterial pressure was observed at the rectal temperature of about 41-42 degrees C. Concomitant decreases in central venous pressure (3 mmHg), stroke volume (2.1 ml/beat) and cardiac output (29 ml/(kg . min)) were observed while heart rate increased (48 beats/min). These results suggest that the decrease in cardiac output during severe hyperthermia is due to the fall of central venous pressure, and the fall was attributed to the increase in unstressed vascular volume of systemic circulation due to the heat-induced cutaneous vasodilation. The observed decrease in systemic vascular compliance is considered to have a significant role in the maintenance of central venous pressure under hyperthermia.

Capillary toroid cavity detector for high pressure NMR

DOEpatents

Gerald, II, Rex E.; Chen, Michael J.; Klingler, Robert J.; Rathke, Jerome W.; ter Horst, Marc

2007-09-11

A Toroid Cavity Detector (TCD) is provided for implementing nuclear magnetic resonance (NMR) studies of chemical reactions under conditions of high pressures and temperatures. A toroid cavity contains an elongated central conductor extending within the toroid cavity. The toroid cavity and central conductor generate an RF magnetic field for NMR analysis. A flow-through capillary sample container is located within the toroid cavity adjacent to the central conductor to subject a sample material flowing through the capillary to a static magnetic field and to enable NMR spectra to be recorded of the material in the capillary under a temperature and high pressure environment.

Closed-Loop Control of Fluid Therapy for Treatment of Hypovolemia

DTIC Science & Technology

2008-04-01

index) (Table 2). Invasive bladder catheterization and blood sampling add the use of urinary output, lactate, central venous oxygen saturation, he...for guiding burn resuscitation Time delay, renal failure, and drugs complicate interpretation Central venous oxygenation ScvO2 Global perfusion index... Central venous pressure (CVP) Sensitive to volume change Pre-injury baseline values vary Arterial pressure by transducer Real-time continuous

Spatial interaction between tissue pressure and skeletal muscle perfusion during contraction.

PubMed

van Donkelaar, C C; Huyghe, J M; Vankan, W J; Drost, M R

2001-05-01

The vascular waterfall theory attributes decreased muscle perfusion during contraction to increased intramuscular pressure (P(IM)) and concomitant increase in venous resistance. Although P(IM) is distributed during contractions, this theory does not account for heterogeneity. This study hypothesises that pressure heterogeneity could affect the interaction between P(IM) rise and perfusion. Regional tissue perfusion during submaximum (100kPa) tetanic contraction is studied, using a finite element model of perfused contracting skeletal muscle. Capillary flow in muscles with one proximal artery and vein (SIM(1)) and with an additional distal artery and vein (SIM(2)) is compared. Blood flow and pressures at rest and P(IM) during contraction ( approximately 25kPa maximally) are similar between simulations, but capillary flow and venous pressure differ. In SIM(2), venous pressure and capillary flow correspond to P(IM) distribution, whereas capillary flow in SIM(1) is less than 10% of flow in SIM(2), in the muscle half without draining vein. This difference is caused by a high central P(IM), followed by central venous pressure rise, in agreement with the waterfall theory. The high central pressure (SIM(1)), obstructs outflow from the distal veins. Distal venous pressure rises until central blood pressure is reached, although local P(IM) is low. Adding a distal vein (SIM(2)) restores the perfusion. It is concluded that regional effects contribute to the interaction between P(IM) and perfusion during contraction. Unlike stated by the vascular waterfall theory, venous pressure may locally exceed P(IM). Although this can be explained by the principles of this theory, the theory does not include this phenomenon as such.

CPAP Devices for Emergency Prehospital Use: A Bench Study.

PubMed

Brusasco, Claudia; Corradi, Francesco; De Ferrari, Alessandra; Ball, Lorenzo; Kacmarek, Robert M; Pelosi, Paolo

2015-12-01

CPAP is frequently used in prehospital and emergency settings. An air-flow output minimum of 60 L/min and a constant positive pressure are 2 important features for a successful CPAP device. Unlike hospital CPAP devices, which require electricity, CPAP devices for ambulance use need only an oxygen source to function. The aim of the study was to evaluate and compare on a bench model the performance of 3 orofacial mask devices (Ventumask, EasyVent, and Boussignac CPAP system) and 2 helmets (Ventukit and EVE Coulisse) used to apply CPAP in the prehospital setting. A static test evaluated air-flow output, positive pressure applied, and FIO2 delivered by each device. A dynamic test assessed airway pressure stability during simulated ventilation. Efficiency of devices was compared based on oxygen flow needed to generate a minimum air flow of 60 L/min at each CPAP setting. The EasyVent and EVE Coulisse devices delivered significantly higher mean air-flow outputs compared with the Ventumask and Ventukit under all CPAP conditions tested. The Boussignac CPAP system never reached an air-flow output of 60 L/min. The EasyVent had significantly lower pressure excursion than the Ventumask at all CPAP levels, and the EVE Coulisse had lower pressure excursion than the Ventukit at 5, 15, and 20 cm H2O, whereas at 10 cm H2O, no significant difference was observed between the 2 devices. Estimated oxygen consumption was lower for the EasyVent and EVE Coulisse compared with the Ventumask and Ventukit. Air-flow output, pressure applied, FIO2 delivered, device oxygen consumption, and ability to maintain air flow at 60 L/min differed significantly among the CPAP devices tested. Only the EasyVent and EVE Coulisse achieved the required minimum level of air-flow output needed to ensure an effective therapy under all CPAP conditions. Copyright © 2015 by Daedalus Enterprises.

[Summary of Research on Relationship Between Core Convective Structure and Intensity Change in Tropical Cyclones

NASA Technical Reports Server (NTRS)

2005-01-01

The downshear reformation of Tropical Storm Gabrielle (2001) was investigated using radar reflectivity and lightning data that were nearly continuous in time, as well as frequent aircraft reconnaissance flights. Initially the storm was a marginal tropical storm in an environment with strong 850-200 hPa vertical wind shear of 12-13 meters per second and an approaching upper tropospheric trough. Both the observed outflow and an adiabatic balance model calculation showed that the radial-vertical circulation increased with time as the trough approached. Convection was highly asymmetric, with almost all radar return located in one quadrant left of downshear in the storm. Reconnaissance data show that an intense mesovortex formed downshear of the original center. This vortex was located just south of, rather than within, a strong downshear left lightning outbreak, consistent with tilting of the horizontal vorticity associated with the vertical wind shear. The downshear mesovortex contained a 972 hPa minimum central pressure, 20 hPa lower than minimum pressure in the original vortex just three hours earlier. The mesovortex became the new center of the storm, but weakened somewhat prior to landfall. It is argued that dry air carried around the storm from the region of upshear subsidence, as well as the direct effects of the shear, prevented the reformed vortex from continuing to intensify. Despite the subsequent weakening of the reformed center, it reached land with greater intensity than the original center. It is argued that this intensification process was set into motion by the vertical wind shear in the presence of an environment with upward motion forced by the upper tropospheric trough. In addition, the new center formed much closer to the coast and made landfall much earlier than predicted. Such vertical shear-induced intensity and track fluctuations are important to understand, especially in storms approaching the coast. The structures of the highly sheared tropical storm Chantal During CAMEX-4 is also discussed.

Local amplification of storm surge by Super Typhoon Haiyan in Leyte Gulf

PubMed Central

Mori, Nobuhito; Kato, Masaya; Kim, Sooyoul; Mase, Hajime; Shibutani, Yoko; Takemi, Tetsuya; Tsuboki, Kazuhisa; Yasuda, Tomohiro

2014-01-01

Typhoon Haiyan, which struck the Philippines in November 2013, was an extremely intense tropical cyclone that had a catastrophic impact. The minimum central pressure of Typhoon Haiyan was 895 hPa, making it the strongest typhoon to make landfall on a major island in the western North Pacific Ocean. The characteristics of Typhoon Haiyan and its related storm surge are estimated by numerical experiments using numerical weather prediction models and a storm surge model. Based on the analysis of best hindcast results, the storm surge level was 5–6 m and local amplification of water surface elevation due to seiche was found to be significant inside Leyte Gulf. The numerical experiments show the coherent structure of the storm surge profile due to the specific bathymetry of Leyte Gulf and the Philippines Trench as a major contributor to the disaster in Tacloban. The numerical results also indicated the sensitivity of storm surge forecast. PMID:25821268

Challenges with Deploying and Integrating Environmental Control and Life Support Functions in a Lunar Architecture with High Degrees of Mobility

NASA Technical Reports Server (NTRS)

Bagdigian, Robert M.

2009-01-01

Visions of lunar outposts often depict a collection of fixed elements such as pressurized habitats, in and around which human inhabitants spend the large majority of their surface stay time. In such an outpost, an efficient deployment of environmental control and life support equipment can be achieved by centralizing certain functions within one or a minimum number of habitable elements and relying on the exchange of gases and liquids between elements via atmosphere ventilation and plumbed interfaces. However, a rigidly fixed outpost can constrain the degree to which the total lunar landscape can be explored. The capability to enable widespread access across the landscape makes a lunar architecture with a high degree of surface mobility attractive. Such mobility presents unique challenges to the efficient deployment of environmental control and life support functions in multiple elements that may for long periods of time be operated independently. This paper describes some of those anticipated challenges.

Bifurcated helical core equilibrium states in tokamaks

NASA Astrophysics Data System (ADS)

Cooper, W. A.; Chapman, I. T.; Schmitz, O.; Turnbull, A. D.; Tobias, B. J.; Lazarus, E. A.; Turco, F.; Lanctot, M. J.; Evans, T. E.; Graves, J. P.; Brunetti, D.; Pfefferlé, D.; Reimerdes, H.; Sauter, O.; Halpern, F. D.; Tran, T. M.; Coda, S.; Duval, B. P.; Labit, B.; Pochelon, A.; Turnyanskiy, M. R.; Lao, L.; Luce, T. C.; Buttery, R.; Ferron, J. R.; Hollmann, E. M.; Petty, C. C.; van Zeeland, M.; Fenstermacher, M. E.; Hanson, J. M.; Lütjens, H.

2013-07-01

Tokamaks with weak to moderate reversed central shear in which the minimum inverse rotational transform (safety factor) qmin is in the neighbourhood of unity can trigger bifurcated magnetohydrodynamic equilibrium states, one of which is similar to a saturated ideal internal kink mode. Peaked prescribed pressure profiles reproduce the ‘snake’ structures observed in many tokamaks which has led to a novel explanation of the snake as a bifurcated equilibrium state. Snake equilibrium structures are computed in simulations of the tokamak à configuration variable (TCV), DIII-D and mega amp spherical torus (MAST) tokamaks. The internal helical deformations only weakly modulate the plasma-vacuum interface which is more sensitive to ripple and resonant magnetic perturbations. On the other hand, the external perturbations do not alter the helical core deformation in a significant manner. The confinement of fast particles in MAST simulations deteriorate with the amplitude of the helical core distortion. These three-dimensional bifurcated solutions constitute a paradigm shift that motivates the applications of tools developed for stellarator research in tokamak physics investigations.

Superconducting energy storage magnet

NASA Technical Reports Server (NTRS)

Boom, Roger W. (Inventor); Eyssa, Yehia M. (Inventor); Abdelsalam, Mostafa K. (Inventor); Huang, Xianrui (Inventor)

1993-01-01

A superconducting magnet is formed having composite conductors arrayed in coils having turns which lie on a surface defining substantially a frustum of a cone. The conical angle with respect to the central axis is preferably selected such that the magnetic pressure on the coil at the widest portion of the cone is substantially zero. The magnet structure is adapted for use as an energy storage magnet mounted in an earthen trench or tunnel where the strength the surrounding soil is lower at the top of the trench or tunnel than at the bottom. The composite conductor may be formed having a ripple shape to minimize stresses during charge up and discharge and has a shape for each ripple selected such that the conductor undergoes a minimum amount of bending during the charge and discharge cycle. By minimizing bending, the working of the normal conductor in the composite conductor is minimized, thereby reducing the increase in resistance of the normal conductor that occurs over time as the conductor undergoes bending during numerous charge and discharge cycles.

Heparin or 0.9% sodium chloride to maintain central venous catheter patency: a randomized trial.

PubMed

Schallom, Marilyn E; Prentice, Donna; Sona, Carrie; Micek, Scott T; Skrupky, Lee P

2012-06-01

To compare heparin (3 mL, 10 units/mL) and 0.9% sodium chloride (NaCl, 10 mL) flush solutions with respect to central venous catheter lumen patency. Single-center, randomized, open label trial. Medical intensive care unit and Surgical/Burn/Trauma intensive care unit at Barnes-Jewish Hospital, St. Louis, MO. Three hundred forty-one patients with multilumen central venous catheters. Patients with at least one lumen with a minimum of two flushes were included in the analysis. Patients were randomly assigned within 12 hrs of central venous catheter insertion to receive either heparin or 0.9% sodium chloride flush. The primary outcome was lumen nonpatency. Secondary outcomes included the rates of loss of blood return, inability to infuse or flush through the lumen (flush failure), heparin-induced thrombocytopenia, and catheter-related blood stream infection. Assessment for patency was performed every 8 hrs in lumens without continuous infusions for the duration of catheter placement or discharge from intensive care unit. Three hundred twenty-six central venous catheters were studied yielding 709 lumens for analysis. The nonpatency rate was 3.8% in the heparin group (n = 314) and 6.3% in the 0.9% sodium chloride group (n = 395) (relative risk 1.66, 95% confidence interval 0.86-3.22, p = .136). The Kaplan-Meier analysis for time to first patency loss was not significantly different (log rank = 0.093) between groups. The rates of loss of blood return and flush failure were similar between the heparin and 0.9% sodium chloride groups. Pressure-injectable central venous catheters had significantly greater rates of nonpatency (10.6% vs. 4.3%, p = .001) and loss of blood return (37.0% vs. 18.8%, p <.001) compared to nonpressure-injectable catheters. The frequencies of heparin-induced thrombocytopenia and catheter-related blood stream infection were similar between groups. 0.9% sodium chloride and heparin flushing solutions have similar rates of lumen nonpatency. Given potential safety concerns with the use of heparin, 0.9% sodium chloride may be the preferred flushing solution for short-term use central venous catheter maintenance.

Performance of transonic fan stage with weight flow per unit annulus area of 178 kilograms per second per square meter (6.5(lb/sec)/(sq ft))

NASA Technical Reports Server (NTRS)

Moore, R. D.; Urasek, D. C.; Kovich, G.

1973-01-01

The overall and blade-element performances are presented over the stable flow operating range from 50 to 100 percent of design speed. Stage peak efficiency of 0.834 was obtained at a weight flow of 26.4 kg/sec (58.3 lb/sec) and a pressure ratio of 1.581. The stall margin for the stage was 7.5 percent based on weight flow and pressure ratio at stall and peak efficiency conditions. The rotor minimum losses were approximately equal to design except in the blade vibration damper region. Stator minimum losses were less than design except in the tip and damper regions.

Effects of smoking on arterial distensibility, central aortic pressures and left ventricular mass.

PubMed

Markus, Marcello Ricardo Paulista; Stritzke, Jan; Baumeister, Sebastian Edgar; Siewert, Ulrike; Baulmann, Johannes; Hannemann, Anke; Schipf, Sabine; Meisinger, Christa; Dörr, Marcus; Felix, Stephan Burkhart; Keil, Ulrich; Völzke, Henry; Hense, Hans-Werner; Schunkert, Heribert

2013-10-03

The effects of smoking on central aortic pressures and the age-related increase in left ventricular mass (LVM) are largely unknown. We studied the relationship between smoking, arterial distensibility, central aortic pressures and left ventricular mass in two population-based studies. Data was obtained from two German population-based studies (KORA and SHIP, participants' ages 25-84 years). We identified 114 normotensive current smokers and 185 normotensive all-time non-smokers in KORA as well as 400 and 588 such individuals in SHIP. Echocardiographic LVM was obtained at baseline (T0) and follow-up after ten years (T1) in KORA and at follow-up (T1) in SHIP. Additionally, pulse-wave analysis-based central aortic pressure and augmentation index (AIx) were measured at T1 in KORA. Cross-sectional analysis, using KORA T0 and SHIP T1, revealed in both studies a higher covariate-adjusted LVM and left ventricular mass index (LVMI) in smokers as compared with non-smokers. Moreover, in the KORA T1 examination, the smokers demonstrated a more pronounced increase, relative to baseline, of LVM (+13.5%) and LVMI (+13.4%) compared to non-smokers (+8.59% and +8.65%; p=0.036 and 0.042, respectively). Additionally, at KORA T1 smokers had a higher central systolic blood pressure and higher AIx than non-smokers (p=0.012 and p=0.001, respectively). The difference in central aortic pressure due to enhanced and more prolonged wave reflection may explain our finding of a further pronounced increase in left ventricular wall thickness and mass over time in smokers. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Increased blood pressures in veterans with post traumatic stress disorder.

PubMed

Moazen-Zadeh, Ehsan; Khoshdel, Alireza; Avakh, Farhad; Rahmani, Arash

2016-08-01

Objective Veterans of war affected by posttraumatic stress disorder (PTSD) are at increased risk for cardiovascular diseases. We aimed to compare brachial and central blood pressures between veterans with PTSD and controls. Method In this case-control study on veterans of Iran-Iraq war, 50 veterans with PTSD and 50 veterans as controls were selected from an outpatient clinic and matched for age ±3 years. Exclusion criteria were malignancies, severe anatomical defects such as amputated extremities, history of PTSD before serving in war, comorbid psychiatric disorders other than anxiety or depressive disorders. Detailed history was taken concerning medical and social aspects. Beck Depression Inventory was used for depressive symptoms. Brachial blood pressures were measured using both auscultatory and oscillometric devices. Measures of central hemodynamics were estimated accordingly. Data on lipid profile were collected either through medical records or newly required lab tests. Results Brachial systolic, diastolic, and pulse pressures as well as estimated central systolic and diastolic pressures were significantly higher in the PTSD group. Beck Depression Inventory scores, frequency of diabetes mellitus, and hypertension were significantly higher in the PTSD group. PTSD status was an independent predictor of both brachial and central systolic and diastolic pressures. Conclusions We demonstrated increased measures of blood pressure in veterans with PTSD independent of depression and other risk factors. Further research is warranted to confirm our results.

A unique concept for automatically controlling the braking action of wheeled vehicles during minimum distance stops

NASA Technical Reports Server (NTRS)

Barthlome, D. E.

1975-01-01

Test results of a unique automatic brake control system are outlined and a comparison is made of its mode of operation to that of an existing skid control system. The purpose of the test system is to provide automatic control of braking action such that hydraulic brake pressure is maintained at a near constant, optimum value during minimum distance stops.

The Effect of Minimum Wages on the Labor Force Participation Rates of Teenagers.

ERIC Educational Resources Information Center

Wessels, Walter J.

In light of pressure on Congress to raise the minimum wage from $5.15 to $6.15 per hour, a study looked at the effects such a raise would have on more than 10 million workers, many of them teenagers. The study used quarterly data on the labor force participation rates of teenagers from 1978 through 1999 and other studies to assess the effects of…

Minimum separation distances for natural gas pipeline and boilers in the 300 area, Hanford Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daling, P.M.; Graham, T.M.

1997-08-01

The U.S. Department of Energy (DOE) is proposing actions to reduce energy expenditures and improve energy system reliability at the 300 Area of the Hanford Site. These actions include replacing the centralized heating system with heating units for individual buildings or groups of buildings, constructing a new natural gas distribution system to provide a fuel source for many of these units, and constructing a central control building to operate and maintain the system. The individual heating units will include steam boilers that are to be housed in individual annex buildings located at some distance away from nearby 300 Area nuclearmore » facilities. This analysis develops the basis for siting the package boilers and natural gas distribution systems to be used to supply steam to 300 Area nuclear facilities. The effects of four potential fire and explosion scenarios involving the boiler and natural gas pipeline were quantified to determine minimum separation distances that would reduce the risks to nearby nuclear facilities. The resulting minimum separation distances are shown in Table ES.1.« less

Pars plana Ahmed valve and vitrectomy in patients with glaucoma associated with posterior segment disease.

PubMed

Wallsh, Josh O; Gallemore, Ron P; Taban, Mehran; Hu, Charles; Sharareh, Behnam

2013-01-01

To assess the safety and efficacy of a modified technique for pars plana placement of the Ahmed valve in combination with pars plana vitrectomy in the treatment of glaucoma associated with posterior segment disease. Thirty-nine eyes with glaucoma associated with posterior segment disease underwent pars plana vitrectomy combined with Ahmed valve placement. All valves were placed in the pars plana using a modified technique, without the pars plana clip, and using a scleral patch graft. The 24 eyes diagnosed with neovascular glaucoma had an improvement in intraocular pressure from 37.6 mmHg to 13.8 mmHg and best-corrected visual acuity from 2.13 logarithm of minimum angle of resolution to 1.40 logarithm of minimum angle of resolution. Fifteen eyes diagnosed with steroid-induced glaucoma had an improvement in intraocular pressure from 27.9 mmHg to 14.1 mmHg and best-corrected visual acuity from 1.38 logarithm of minimum angle of resolution to 1.13 logarithm of minimum angle of resolution. Complications included four cases of cystic bleb formation and one case of choroidal detachment and explantation for hypotony. Ahmed valve placement through the pars plana during vitrectomy is an effective option for managing complex cases of glaucoma without the use of the pars plana clip.

Pressure-enhanced ortho-para conversion in solid hydrogen up to 58 GPa.

PubMed

Eggert, J H; Karmon, E; Hemley, R J; Mao, A; Goncharov, A F

1999-10-26

We measured the ortho-para conversion rate in solid hydrogen by using Raman scattering in a diamond-anvil cell, extending previous measurements by a factor of 60 in pressure. We confirm previous experiments that suggested a decrease in the conversion rate above about 0.5 GPa. We observe a distinct minimum at 3 GPa followed by a drastic increase in the conversion rate to our maximum pressure of 58 GPa. This pressure enhancement of conversion is not predicted by previous theoretical treatments and must be due to a new conversion pathway.

Simplified configuration for the combustor of an oil burner using a low pressure, high flow air-atomizing nozzle

DOEpatents

Butcher, Thomas A.; Celebi, Yusuf; Fisher, Leonard

2000-09-15

The invention relates to clean burning of fuel oil with air. More specifically, to a fuel burning combustion head using a low-pressure, high air flow atomizing nozzle so that there will be a complete combustion of oil resulting in a minimum emission of pollutants. The improved fuel burner uses a low pressure air atomizing nozzle that does not result in the use of additional compressors or the introduction of pressurized gases downstream, nor does it require a complex design. Inventors:

Evaluation of the monitor cursor-line method for measuring pulmonary artery and central venous pressures.

PubMed

Pasion, Editha; Good, Levell; Tizon, Jisebelle; Krieger, Staci; O'Kier, Catherine; Taylor, Nicole; Johnson, Jennifer; Horton, Carrie M; Peterson, Mary

2010-11-01

To determine if the monitor cursor-line feature on bedside monitors is accurate for measuring central venous and pulmonary artery pressures in cardiac surgery patients. Central venous and pulmonary artery pressures were measured via 3 methods (end-expiratory graphic recording, monitor cursor-line display, and monitor digital display) in a convenience sample of postoperative cardiac surgery patients. Pressures were measured twice during both mechanical ventilation and spontaneous breathing. Analysis of variance was used to determine differences between measurement methods and the percentage of monitor pressures that differed by 4 mm Hg or more from the measurement obtained from the graphic recording. Significance level was set at P less than .05. Twenty-five patients were studied during mechanical ventilation (50 measurements) and 21 patients during spontaneous breathing (42 measurements). Measurements obtained via the 3 methods did not differ significantly for either type of pressure (P > .05). Graphically recorded pressures and measurements obtained via the monitor cursor-line or digital display methods differed by 4 mm Hg or more in 4% and 6% of measurements, respectively, during mechanical ventilation and 4% and 11%, respectively, during spontaneous breathing. The monitor cursor-line method for measuring central venous and pulmonary artery pressures may be a reasonable alternative to the end-expiratory graphic recording method in hemodynamically stable, postoperative cardiac surgery patients. Use of the digital display on the bedside monitor may result in larger discrepancies from the graphically recorded pressures than when the cursor-line method is used, particularly in spontaneously breathing patients.

30 CFR 250.522 - When do I have to repeat casing diagnostic testing?

Code of Federal Regulations, 2010 CFR

2010-07-01

..., previously on gas lift, has been shut-in or returned to flowing status without gas lift for more than 180... active gas lift are exempt from diagnostic testing. (c) your casing pressure request becomes invalid... percent of its minimum internal yield pressure (MIYP), except for production casings on active gas lift...

30 CFR 250.523 - How long do I keep records of casing pressure and diagnostic tests?

Code of Federal Regulations, 2010 CFR

2010-07-01

... field office nearest the well for a minimum of 2 years. The last casing diagnostic test for each casing... and diagnostic tests? 250.523 Section 250.523 Mineral Resources MINERALS MANAGEMENT SERVICE... Gas Well-Completion Operations Casing Pressure Management § 250.523 How long do I keep records of...

46 CFR 154.560 - Cargo hose: Prototype test.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Cargo hose: Prototype test. 154.560 Section 154.560... Hose § 154.560 Cargo hose: Prototype test. (a) Each cargo hose must be of a type that passes a prototype test at a pressure of at least five times its maximum working pressure at or below the minimum...

40 CFR Table 3 to Subpart Dddd of... - Model Rule-Operating Limits for Wet Scrubbers

Code of Federal Regulations, 2010 CFR

2010-07-01

... Scrubbers 3 Table 3 to Subpart DDDD of Part 60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY...—Model Rule—Operating Limits for Wet Scrubbers For these operating parameters You must establish these... intermittent units) a Pressure drop across the wet scrubber or amperage to wet scrubber Minimum pressure drop...

40 CFR Table 3 to Subpart Dddd of... - Model Rule-Operating Limits for Wet Scrubbers

Code of Federal Regulations, 2011 CFR

2011-07-01

... Scrubbers 3 Table 3 to Subpart DDDD of Part 60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY...—Model Rule—Operating Limits for Wet Scrubbers For these operating parameters You must establish these... intermittent units) a Pressure drop across the wet scrubber or amperage to wet scrubber Minimum pressure drop...

Inspiratory Resistance as a Potential Treatment for Orthostatic Intolerance and Hemorrhagic Shock

DTIC Science & Technology

2005-04-01

central blood volume by forcing the thoracic muscles to develop increased negative pressure , thus drawing venous blood from extrathoracic cavi- ties...cardiac baroreflex sensitivity associated with re- ductions of central blood volume during lower body negative pressure (LBNP) are reversed with...9:621–26. 8. Chapleau MW, Abboud FM. Contrasting effects of static and pulsatile pressure on carotid baroreceptor activity in dogs. Circ Res 1987; 61

Association of physical examination with pulmonary artery catheter parameters in acute lung injury.

PubMed

Grissom, Colin K; Morris, Alan H; Lanken, Paul N; Ancukiewicz, Marek; Orme, James F; Schoenfeld, David A; Thompson, B Taylor

2009-10-01

To correlate physical examination findings, central venous pressure, fluid output, and central venous oxygen saturation with pulmonary artery catheter parameters. Retrospective study. Data from the multicenter Fluid and Catheter Treatment Trial of the National Institutes of Health Acute Respiratory Distress Syndrome Network. Five hundred thirteen patients with acute lung injury randomized to treatment with a pulmonary artery catheter. Correlation of physical examination findings (capillary refill time >2 secs, knee mottling, or cool extremities), central venous pressure, fluid output, and central venous oxygen saturation with parameters from a pulmonary artery catheter. We determined association of baseline physical examination findings and on-study parameters of central venous pressure and central venous oxygen saturation with cardiac index <2.5 L/min/m2 and mixed venous oxygen saturation <60%. We determined correlation of baseline central venous oxygen saturation and mixed venous oxygen saturation and predictive value of a low central venous oxygen saturation for a low mixed venous oxygen saturation. Prevalence of cardiac index <2.5 and mixed venous oxygen saturation <60% was 8.1% and 15.5%, respectively. Baseline presence of all three physical examination findings had low sensitivity (12% and 8%), high specificity (98% and 99%), low positive predictive value (40% and 56%), but high negative predictive value (93% and 86%) for cardiac index <2.5 and mixed venous oxygen saturation <60%, respectively. Central venous oxygen saturation <70% predicted a mixed venous oxygen saturation <60% with a sensitivity 84%,specificity 70%, positive predictive value 31%, and negative predictive value of 96%. Low cardiac index correlated with cool extremities, high central venous pressure, and low 24-hr fluid output; and low mixed venous oxygen saturation correlated with knee mottling and high central venous pressure, but these correlations were not found to be clinically useful. In this subset of patients with acute lung injury, there is a high prior probability that cardiac index and mixed venous oxygen saturation are normal and physical examination findings of ineffective circulation are not useful for predicting low cardiac index or mixed venous oxygen saturation. Central venous oxygen saturation <70% does not accurately predict mixed venous oxygen saturation <60%, but a central venous oxygen saturation >or=70% may be useful to exclude mixed venous oxygen saturation <60%.

Blood pressure and the contractility of a human leg muscle.

PubMed

Luu, Billy L; Fitzpatrick, Richard C

2013-11-01

These studies investigate the relationships between perfusion pressure, force output and pressor responses for the contracting human tibialis anterior muscle. Eight healthy adults were studied. Changing the height of tibialis anterior relative to the heart was used to control local perfusion pressure. Electrically stimulated tetanic force output was highly sensitive to physiological variations in perfusion pressure showing a proportionate change in force output of 6.5% per 10 mmHg. This perfusion-dependent change in contractility begins within seconds and is reversible with a 53 s time constant, demonstrating a steady-state equilibrium between contractility and perfusion pressure. These stimulated contractions did not produce significant cardiovascular responses, indicating that the muscle pressor response does not play a major role in cardiovascular regulation at these workloads. Voluntary contractions at forces that would require constant motor drive if perfusion pressure had remained constant generated a central pressor response when perfusion pressure was lowered. This is consistent with a larger cortical drive being required to compensate for the lost contractility with lower perfusion pressure. The relationship between contractility and perfusion for this large postural muscle was not different from that of a small hand muscle (adductor pollicis) and it responded similarly to passive peripheral and active central changes in arterial pressure, but extended over a wider operating range of pressures. If we consider that, in a goal-oriented motor task, muscle contractility determines central motor output and the central pressor response, these results indicate that muscle would fatigue twice as fast without a pressor response. From its extent, timing and reversibility we propose a testable hypothesis that this change in contractility arises through contraction- and perfusion-dependent changes in interstitial K(+) concentration.

Blood pressure and the contractility of a human leg muscle

PubMed Central

Luu, Billy L; Fitzpatrick, Richard C

2013-01-01

These studies investigate the relationships between perfusion pressure, force output and pressor responses for the contracting human tibialis anterior muscle. Eight healthy adults were studied. Changing the height of tibialis anterior relative to the heart was used to control local perfusion pressure. Electrically stimulated tetanic force output was highly sensitive to physiological variations in perfusion pressure showing a proportionate change in force output of 6.5% per 10 mmHg. This perfusion-dependent change in contractility begins within seconds and is reversible with a 53 s time constant, demonstrating a steady-state equilibrium between contractility and perfusion pressure. These stimulated contractions did not produce significant cardiovascular responses, indicating that the muscle pressor response does not play a major role in cardiovascular regulation at these workloads. Voluntary contractions at forces that would require constant motor drive if perfusion pressure had remained constant generated a central pressor response when perfusion pressure was lowered. This is consistent with a larger cortical drive being required to compensate for the lost contractility with lower perfusion pressure. The relationship between contractility and perfusion for this large postural muscle was not different from that of a small hand muscle (adductor pollicis) and it responded similarly to passive peripheral and active central changes in arterial pressure, but extended over a wider operating range of pressures. If we consider that, in a goal-oriented motor task, muscle contractility determines central motor output and the central pressor response, these results indicate that muscle would fatigue twice as fast without a pressor response. From its extent, timing and reversibility we propose a testable hypothesis that this change in contractility arises through contraction- and perfusion-dependent changes in interstitial K+ concentration. PMID:24018946

Low central venous pressure versus acute normovolemic hemodilution versus conventional fluid management for reducing blood loss in radical retropubic prostatectomy: a randomized controlled trial.

PubMed

Habib, Ashraf S; Moul, Judd W; Polascik, Thomas J; Robertson, Cary N; Roche, Anthony M; White, William D; Hill, Stephen E; Nosnick, Israel; Gan, Tong J

2014-05-01

To compare acute normovolemic hemodilution versus low central venous pressure strategy versus conventional fluid management in reducing intraoperative estimated blood loss, hematocrit drop and need for blood transfusion in patients undergoing radical retropubic prostatectomy under general anesthesia. Patients undergoing radical retropubic prostatectomy under general anesthesia were randomized to conventional fluid management, acute normovolemic hemodilution or low central venous pressure (≤5 mmHg). Treatment effects on estimated blood loss and hematocrit change were tested in multivariable regression models accounting for surgeon, prostate size, and all two-way interactions. Ninety-two patients completed the study. Estimated blood loss (mean ± SD) was significantly lower with low central venous pressure (706 ± 362 ml) compared to acute normovolemic hemodilution (1103 ± 635 ml) and conventional (1051 ± 714 ml) groups (p = 0.0134). There was no difference between the groups in need for blood transfusion, or hematocrit drop from preoperative values. The multivariate model predicting estimated blood loss showed a significant effect of treatment (p = 0.0028) and prostate size (p = 0.0323), accounting for surgeon (p = 0.0013). In the model predicting hematocrit change, accounting for surgeon difference (p = 0.0037), the treatment effect depended on prostate size (p = 0.0007) with the slope of low central venous pressure differing from the other two groups. Hematocrit was predicted to drop more with increased prostate size in acute normovolemic hemodilution and conventional groups but not with low central venous pressure. Limitations include the inability to blind providers to group assignment, possible variability between providers in estimation of blood loss, and the relatively small sample size that was not powered to detect differences between the groups in need for blood transfusion. Maintaining low central venous pressure reduced estimated blood loss compared to conventional fluid management and acute normovolemic hemodilution in patients undergoing radical retropubic prostatectomy but there was no difference in allogeneic blood transfusion between the groups.

40 CFR Appendix III to Part 86 - Constant Volume Sampler Flow Calibration

Code of Federal Regulations, 2014 CFR

2014-07-01

... ETI °F ±.1°F. Pressure depression upstream of LFE EPI “H20 ±.1“H20. Pressure drop across the LFE matrix EDP “H20 ±.005“H20. Air temperature at CVS pump inlet PTI °F ±.5°F. Pressure depression at CVS... condition in an increment of pump inlet depression (about 4″ H2O) that will yield a minimum of six data...

40 CFR Appendix III to Part 86 - Constant Volume Sampler Flow Calibration

Code of Federal Regulations, 2010 CFR

2010-07-01

... ETI °F ±.1 °F. Pressure depression upstream of LFE EPI “H20 ±.1“H20. Pressure drop across the LFE matrix EDP “H20 ±.005“H20. Air temperature at CVS pump inlet PTI °F ±.5 °F. Pressure depression at CVS... condition in an increment of pump inlet depression (about 4″ H2O) that will yield a minimum of six data...

40 CFR Appendix III to Part 86 - Constant Volume Sampler Flow Calibration

Code of Federal Regulations, 2013 CFR

2013-07-01

... ETI °F ±.1 °F. Pressure depression upstream of LFE EPI “H20 ±.1“H20. Pressure drop across the LFE matrix EDP “H20 ±.005“H20. Air temperature at CVS pump inlet PTI °F ±.5 °F. Pressure depression at CVS... condition in an increment of pump inlet depression (about 4″ H2O) that will yield a minimum of six data...

40 CFR Appendix III to Part 86 - Constant Volume Sampler Flow Calibration

Code of Federal Regulations, 2011 CFR

2011-07-01

... ETI °F ±.1 °F. Pressure depression upstream of LFE EPI “H20 ±.1“H20. Pressure drop across the LFE matrix EDP “H20 ±.005“H20. Air temperature at CVS pump inlet PTI °F ±.5 °F. Pressure depression at CVS... condition in an increment of pump inlet depression (about 4″ H2O) that will yield a minimum of six data...

40 CFR Appendix III to Part 86 - Constant Volume Sampler Flow Calibration

Code of Federal Regulations, 2012 CFR

2012-07-01

... ETI °F ±.1 °F. Pressure depression upstream of LFE EPI “H20 ±.1“H20. Pressure drop across the LFE matrix EDP “H20 ±.005“H20. Air temperature at CVS pump inlet PTI °F ±.5 °F. Pressure depression at CVS... condition in an increment of pump inlet depression (about 4″ H2O) that will yield a minimum of six data...

Transient Pressure Measurements in the Vaneless Space of a Francis Turbine during Load Acceptances from Minimum Load

NASA Astrophysics Data System (ADS)

Goyal, R.; Gandhi, B. K.; Cervantes, M. J.

2018-06-01

Increased penetration of solar and the wind impels the designers of the hydroelectric power generation unit to provide more flexibility in operation for the stability of the grid. The power generating unit includes turbine which needs to sustain sudden change in its operating conditions. Thus, the hydraulic turbine experiences more transients per day which result in chronic problems such as fatigue to the runner, instrument malfunctioning, vibrations, wear and tear etc. This paper describes experiments performed on a high model (1.5:1) Francis turbine for load acceptances from the minimum load. The experiments presented in the paper are the part of Francis-99 workshop which aims to determine the performance of numerical models in simulations of model Francis turbine under steady and transient operating conditions. The aim of the paper is to present the transient pressure variation in the vaneless space of a Francis turbine where high-frequency pulsations are normally expected. For this, two pressure sensors, VL1 and VL2, are mounted at the vaneless space, one near the beginning of the spiral casing and the other before the end of the spiral casing. Both are used to capture the unsteady pressure field developed in the space between guide vanes and runner inlet. The time-resolved pressure signals are analyzed and presented during the transient to observe the pressure variation and dominant frequencies of pulsations.

White matter hyperintensities in migraine: Clinical significance and central pulsatile hemodynamic correlates.

PubMed

Cheng, Chun-Yu; Cheng, Hao-Min; Chen, Shih-Pin; Chung, Chih-Ping; Lin, Yung-Yang; Hu, Han-Hwa; Chen, Chen-Huan; Wang, Shuu-Jiun

2018-06-01

Background The role of central pulsatile hemodynamics in the pathogenesis of white matter hyperintensities in migraine patients has not been clarified. Methods Sixty patients with migraine (20-50 years old; women, 68%) without overt vascular risk factors and 30 demographically-matched healthy controls were recruited prospectively. Cerebral white matter hyperintensities volume was determined by T1-weighted magnetic resonance imaging with CUBE-fluid-attenuated-inversion-recovery sequences. Central systolic blood pressure, carotid-femoral pulse wave velocity, and carotid augmentation index were measured by applanation tonometry. Carotid pulsatility index was derived from Doppler ultrasound carotid artery flow analysis. Results Compared to the controls, the migraine patients had higher white matter hyperintensities frequency (odds ratio, 2.75; p = 0.04) and greater mean white matter hyperintensities volume (0.174 vs. 0.049, cm 3 , p = 0.04). Multivariable regression analysis showed that white matter hyperintensities volume in migraine patients was positively associated with central systolic blood pressure ( p = 0.04) and carotid-femoral pulse wave velocity ( p < 0.001), but negatively associated with carotid pulsatility index ( p = 0.04) after controlling for potential confounding factors. The interaction effects observed indicated that the influence of carotid-femoral pulse wave velocity ( p = 0.004) and central systolic blood pressure ( p = 0.03) on white matter hyperintensities formation was greater for the lower-carotid pulsatility index subgroup of migraine patients. White matter hyperintensities volume in migraine patients increased with decreasing carotid pulsatility index and with increasing central systolic blood pressure or carotid-femoral pulse wave velocity. Conclusions White matter hyperintensities are more common in patients with migraine than in healthy controls. Increased aortic stiffness or central systolic blood pressure in the presence of low intracranial artery resistance may predispose patients with migraine to white matter hyperintensities formation.

Influence of low and high pressure baroreceptors on plasma renin activity in humans

NASA Technical Reports Server (NTRS)

Mark, A. L.; Abboud, F. M.; Fitz, A. E.

1977-01-01

The effects of low and high pressure baroreceptors on plasma renin activity (immunoassay) were evaluated using graded lower body suction (LBS) in six healthy men. LBS at -10 and -20 mmHg for 10 min decreased central venous pressure without changing arterial pressure and thereby presumably reduced low but not high pressure baroreceptor inhibition of renin release. LBS at these levels produced forearm vasoconstriction, but did not increase renin. LBS at -40 mmHG decreased central venous and arterial pulse pressure and thus reduced both low and high pressure baroreceptor inhibition. LBS at this level produced forearm vasoconstriction and tachycardia and increased renin. In summary, reduction in low pressure baroreceptor inhibition in humans did not increase renin in the presence of physiological tonic inhibition from high pressure baroreceptors. Increases in renin did not occur until there was combined reduction of high and low pressure baroreceptor inhibition on plasma renin activity.

Advanced space engine preliminary design

NASA Technical Reports Server (NTRS)

Cuffe, J. P. B.; Bradie, R. E.

1973-01-01

A preliminary design was completed for an O2/H2, 89 kN (20,000 lb) thrust staged combustion rocket engine that has a single-bell nozzle with an overall expansion ratio of 400:1. The engine has a best estimate vacuum specific impulse of 4623.8 N-s/kg (471.5 sec) at full thrust and mixture ratio = 6.0. The engine employs gear-driven, low pressure pumps to provide low NPSH capability while individual turbine-driven, high-speed main pumps provide the system pressures required for high-chamber pressure operation. The engine design dry weight for the fixed-nozzle configuration is 206.9 kg (456.3 lb). Engine overall length is 234 cm (92.1 in.). The extendible nozzle version has a stowed length of 141.5 cm (55.7 in.). Critical technology items in the development of the engine were defined. Development program plans and their costs for development, production, operation, and flight support of the ASE were established for minimum cost and minimum time programs.

Lunar mass spectrometer test program

NASA Technical Reports Server (NTRS)

Torney, F. L.; Dobrott, J. R.

1972-01-01

The procedures are described along with results obtained in a test program conducted to demonstrate the performance of a candidate lunar mass spectrometer. The instrument was designed to sample and measure gases believed to exist in the lunar atmosphere at the surface. The subject instrument consists of a cold cathode ion source, a small quadrupole mass analyzer and an off axis electron multiplier ion counting detector. The major program emphasis was placed on demonstrating instrument resolution, sensitivity and S/N ratio over the mass range 0-150 amu and over a partial pressure range from 10 to the minus 9th power to 10 to the minus 13th power torr. Ultrahigh vacuum tests were conducted and the minimum detectable partial pressure for neon, argon, krypton and xenon was successfully determined for the spectrometer using isotopes of these gases. With the exception of neon, the minimum detectable partial pressure is approximately 4 x 10 to the minus 14th power torr for the above gases.

Groundwater-level trends in the U.S. glacial aquifer system, 1964-2013

USGS Publications Warehouse

Hodgkins, Glenn A.; Dudley, Robert W.; Nielsen, Martha G.; Renard, Benjamin; Qi, Sharon L.

2017-01-01

The glacial aquifer system in the United States is a major source of water supply but previous work on historical groundwater trends across the system is lacking. Trends in annual minimum, mean, and maximum groundwater levels for 205 monitoring wells were analyzed across three regions of the system (East, Central, West Central) for four time periods: 1964-2013, 1974-2013, 1984-2013, and 1994-2013. Trends were computed separately for wells in the glacial aquifer system with low potential for human influence on groundwater levels and ones with high potential influence from activities such as groundwater pumping. Generally there were more wells with significantly increasing groundwater levels (levels closer to ground surface) than wells with significantly decreasing levels. The highest numbers of significant increases for all four time periods were with annual minimum and/or mean levels. There were many more wells with significant increases from 1964 to 2013 than from more recent periods, consistent with low precipitation in the 1960s. Overall there were low numbers of wells with significantly decreasing trends regardless of time period considered; the highest number of these were generally for annual minimum groundwater levels at wells with likely human influence. There were substantial differences in the number of wells with significant groundwater-level trends over time, depending on whether the historical time series are assumed to be independent, have short-term persistence, or have long-term persistence. Mean annual groundwater levels have significant lag-one-year autocorrelation at 26.0% of wells in the East region, 65.4% of wells in the Central region, and 100% of wells in the West Central region. Annual precipitation across the glacial aquifer system, on the other hand, has significant autocorrelation at only 5.5% of stations, about the percentage expected due to chance.

Vaporization chemistry of hypo-stoichiometric (U,Pu)O 2

NASA Astrophysics Data System (ADS)

Viswanathan, R.; Krishnaiah, M. V.

2001-04-01

Calculations were performed on hypo-stoichiometric uranium plutonium di-oxide to examine its vaporization behavior as a function of O/ M ( M= U+ Pu) ratio and plutonium content. The phase U (1- y) Pu yO z was treated as an ideal solid solution of (1- y)UO 2+ yPuO (2- x) such that x=(2- z)/ y. Oxygen potentials for different desired values of y, z, and temperature were used as the primary input to calculate the corresponding partial pressures of various O-, U-, and Pu-bearing gaseous species. Relevant thermodynamic data for the solid phases UO 2 and PuO (2- x) , and the gaseous species were taken from the literature. Total vapor pressure varies with O/M and goes through a minimum. This minimum does not indicate a congruently vaporizing composition. Vaporization behavior of this system can at best be quasi-congruent. Two quasi-congruently vaporizing compositions (QCVCs) exist, representing the equalities (O/M) vapor=(O/M) mixed-oxide and (U/Pu) vapor=(U/Pu) mixed-oxide, respectively. The (O/M) corresponding to QCVC1 is lower than that corresponding to QCVC2, but very close to the value where vapor pressure minimum occurs. The O/M values of both QCVCs increase with decrease in plutonium content. The vaporization chemistry of this system, on continuous vaporization under dynamic condition, is discussed.

Non-invasive Positive Pressure Ventilation during Sleep at 3800m: relationship to Acute Mountain Sickness and sleeping oxyhemoglobin saturation

PubMed Central

Johnson, PL; Popa, DA; Prisk, GK; Sullivan, CE; Edwards, N

2014-01-01

Background and objectives Ascent to high altitude results in hypobaric hypoxia and some individuals will develop Acute Mountain Sickness, which has been shown to be associated with low oxyhemoglobin saturation during sleep. Previous research has shown that positive end-expiratory pressure by use of expiratory valves in a face mask while awake, results in a reduction in AMS symptoms and higher oxyhemoglobin saturation. We aimed to test whether pressure ventilation during sleep would prevent AMS by keeping oxyhaemoglobin higher during sleep. Methods We compared sleeping oxyhemoglobin saturation and the incidence and severity of Acute Mountain Sickness in seven subjects sleeping for two consecutive nights at 3800m above sea level using either non-invasive positive pressure ventilation that delivered positive inspiratory and expiratory airway pressure via a face mask, or sleeping without assisted ventilation. The presence and severity of Acute Mountain Sickness was assessed by administration of the Lake Louise questionnaire. Results We found significant increases in the mean and minimum sleeping oxyhemoglobin saturation and decreases in AMS symptoms in subjects who used positive pressure ventilation during sleep. Mean and minimum sleeping SaO2 was lower in subjects who developed AMS after the night spent without positive pressure ventilation. Conclusion The use of positive pressure ventilation during sleep at 3800m significantly increased the sleeping oxygen saturation; we suggest that the marked reduction in symptoms of AMS is due to this higher sleeping SaO2. We agree with the findings from previous studies that the development of AMS is associated with a lower sleeping oxygen saturation. PMID:20051046

A Possible Cause of the Diminished Solar Wind During the Solar Cycle 23 - 24 Minimum

NASA Astrophysics Data System (ADS)

Liou, Kan; Wu, Chin-Chun

2016-12-01

Interplanetary magnetic field and solar wind plasma density observed at 1 AU during Solar Cycle 23 - 24 (SC-23/24) minimum were significantly smaller than those during its previous solar cycle (SC-22/23) minimum. Because the Earth's orbit is embedded in the slow wind during solar minimum, changes in the geometry and/or content of the slow wind region (SWR) can have a direct influence on the solar wind parameters near the Earth. In this study, we analyze solar wind plasma and magnetic field data of hourly values acquired by Ulysses. It is found that the solar wind, when averaging over the first (1995.6 - 1995.8) and third (2006.9 - 2008.2) Ulysses' perihelion ({˜} 1.4 AU) crossings, was about the same speed, but significantly less dense ({˜} 34 %) and cooler ({˜} 20 %), and the total magnetic field was {˜} 30 % weaker during the third compared to the first crossing. It is also found that the SWR was {˜} 50 % wider in the third ({˜} 68.5^deg; in heliographic latitude) than in the first ({˜} 44.8°) solar orbit. The observed latitudinal increase in the SWR is sufficient to explain the excessive decline in the near-Earth solar wind density during the recent solar minimum without speculating that the total solar output may have been decreasing. The observed SWR inflation is also consistent with a cooler solar wind in the SC-23/24 than in the SC-22/23 minimum. Furthermore, the ratio of the high-to-low latitude photospheric magnetic field (or equatorward magnetic pressure force), as observed by the Mountain Wilson Observatory, is smaller during the third than the first Ulysses' perihelion orbit. These findings suggest that the smaller equatorward magnetic pressure at the Sun may have led to the latitudinally-wider SRW observed by Ulysses in SC-23/24 minimum.

Twenty-four-hour central blood pressure is not better associated with hypertensive target organ damage than 24-h peripheral blood pressure.

PubMed

de la Sierra, Alejandro; Pareja, Julia; Fernández-Llama, Patricia; Armario, Pedro; Yun, Sergi; Acosta, Eva; Calero, Francesca; Vázquez, Susana; Blanch, Pedro; Sierra, Cristina; Oliveras, Anna

2017-10-01

Central blood pressure (BP) is increasingly considered as a better estimator of hypertension associated risks. We aimed to evaluate the association of 24-h central BP, in comparison with 24-h peripheral BP, with the presence of target organ damage (TOD). Cross-sectional study of 208 hypertensive patients, aged 57 ± 12 years, 34% women. Office (mean of 4 measurements) and 24-h central and peripheral BP were measured by the oscillometric Mobil-O-Graph device. TOD was assessed at cardiac (left ventricular hypertrophy by echocardiography), renal (reduction of glomerular filtration rate and/or microalbuminuria), and arterial (increased aortic pulse wave velocity) levels. A total of 107 patients (51.4%) had TOD (77, 35% patients left ventricular hypertrophy; 54, 25.9% renal abnormalities; and 40, 19.2% arterial stiffness). All SBP and pulse BP estimates (office, 24-h, daytime, and night-time) were associated with the presence of TOD, after adjustment for age, sex, and antihypertensive treatment, with higher odds ratios for ambulatory-derived values. Odds ratios for central and peripheral BP were similar for all office, 24-h, daytime, and night-time BP. After simultaneous adjustment, peripheral, but not central, 24-h and night-time SBP and pulse pressures were associated with the presence of TOD. TOD in hypertension is associated with BP elevation, independently of the type of measurement (office or ambulatory, central or peripheral). Central BP, even monitored during 24 h, is not better associated with TOD than peripheral BP. These results do not support a routine measurement of 24-h central BP.

An explanation for the tiny value of the cosmological constant and the low vacuum energy density

NASA Astrophysics Data System (ADS)

Nassif, Cláudio

2015-09-01

The paper aims to provide an explanation for the tiny value of the cosmological constant and the low vacuum energy density to represent the dark energy. To accomplish this, we will search for a fundamental principle of symmetry in space-time by means of the elimination of the classical idea of rest, by including an invariant minimum limit of speed in the subatomic world. Such a minimum speed, unattainable by particles, represents a preferred reference frame associated with a background field that breaks down the Lorentz symmetry. The metric of the flat space-time shall include the presence of a uniform vacuum energy density, which leads to a negative pressure at cosmological length scales. Thus, the equation of state for the cosmological constant [ p(pressure) (energy density)] naturally emerges from such a space-time with an energy barrier of a minimum speed. The tiny values of the cosmological constant and the vacuum energy density will be successfully obtained, being in agreement with the observational results of Perlmutter, Schmidt and Riess.

Determining the minimum in situ stress from hydraulic fracturing through perforations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warpinski, N.R.

Hydraulic fracture stress measurements have been performed through perforations at depths from 1310 to 2470 m at the US Department of Energy's Multiwell Experiment site. The results of over sixty stress tests conducted through perforations have shown that small-volume hydraulic fractures generally provide an accurate, reproducible measurement of the minimum in situ stress. However, unusual behavior can occur in some tests and techniques to evaluate the behavior are suggested. Unclear instantaneous shut-in pressures, which are found on occasional tests, are difficult to evaluate, but the problem appears to be a complex stress state; reprocessing the data using log-log or othermore » functions does not necessarily provide the correct stress value. The possible error in such tests should be assessed from the original pressure-time data and not the reprocessing techniques. Stress results show that the stress distribution is dependent on lithology at this site; mudstones, shales and other nonreservoir rocks generally have a near-lithostatic stress, while sandstones have a considerably lower minimum stress value. 30 refs., 18 figs., 4 tabs.« less

The influence of central command on baroreflex resetting during exercise

NASA Technical Reports Server (NTRS)

Raven, Peter B.; Fadel, Paul J.; Smith, Scott A.

2002-01-01

The arterial baroreflex functions as a negative feedback system regulating blood pressure around an established operating point. Paradoxically, a parallel increase in heart rate and blood pressure manifests during exercise. Experimental evidence suggests these events are caused, in part, by a rapid resetting of the baroreflex by central command.

Feedback Regulation of Intracellular Hydrostatic Pressure in Surface Cells of the Lens

PubMed Central

Gao, Junyuan; Sun, Xiurong; White, Thomas W.; Delamere, Nicholas A.; Mathias, Richard T.

2015-01-01

In wild-type lenses from various species, an intracellular hydrostatic pressure gradient goes from ∼340 mmHg in central fiber cells to 0 mmHg in surface cells. This gradient drives a center-to-surface flow of intracellular fluid. In lenses in which gap-junction coupling is increased, the central pressure is lower, whereas if gap-junction coupling is reduced, the central pressure is higher but surface pressure is always zero. Recently, we found that surface cell pressure was elevated in PTEN null lenses. This suggested disruption of a feedback control system that normally maintained zero surface cell pressure. Our purpose in this study was to investigate and characterize this feedback control system. We measured intracellular hydrostatic pressures in mouse lenses using a microelectrode/manometer-based system. We found that all feedback went through transport by the Na/K ATPase, which adjusted surface cell osmolarity such that pressure was maintained at zero. We traced the regulation of Na/K ATPase activity back to either TRPV4, which sensed positive pressure and stimulated activity, or TRPV1, which sensed negative pressure and inhibited activity. The inhibitory effect of TRPV1 on Na/K pumps was shown to signal through activation of the PI3K/AKT axis. The stimulatory effect of TRPV4 was shown in previous studies to go through a different signal transduction path. Thus, there is a local two-legged feedback control system for pressure in lens surface cells. The surface pressure provides a pedestal on which the pressure gradient sits, so surface pressure determines the absolute value of pressure at each radial location. We speculate that the absolute value of intracellular pressure may set the radial gradient in the refractive index, which is essential for visual acuity. PMID:26536260

Peripheral vascular effects on auscultatory blood pressure measurement.

PubMed

Rabbany, S Y; Drzewiecki, G M; Noordergraaf, A

1993-01-01

Experiments were conducted to examine the accuracy of the conventional auscultatory method of blood pressure measurement. The influence of the physiologic state of the vascular system in the forearm distal to the site of Korotkoff sound recording and its impact on the precision of the measured blood pressure is discussed. The peripheral resistance in the arm distal to the cuff was changed noninvasively by heating and cooling effects and by induction of reactive hyperemia. All interventions were preceded by an investigation of their effect on central blood pressure to distinguish local effects from changes in central blood pressure. These interventions were sufficiently moderate to make their effect on central blood pressure, recorded in the other arm, statistically insignificant (i.e., changes in systolic [p < 0.3] and diastolic [p < 0.02]). Nevertheless, such alterations were found to modify the amplitude of the Korotkoff sound, which can manifest itself as an apparent change in arterial blood pressure that is readily discerned by the human ear. The increase in diastolic pressure for the cooling experiments was statistically significant (p < 0.001). Moreover, both measured systolic (p < 0.004) and diastolic (p < 0.001) pressure decreases during the reactive hyperemia experiments were statistically significant. The findings demonstrate that alteration in vascular state generates perplexing changes in blood pressure, hence confirming experimental observations by earlier investigators as well as predictions by our model studies.

Relationships between 24-h blood pressure variability and 24-h central arterial pressure, pulse wave velocity and augmentation index in hypertensive patients.

PubMed

Omboni, Stefano; Posokhov, Igor N; Rogoza, Anatoly N

2017-04-01

Twenty-four-h blood pressure variability (BPV) predicts cardiovascular complications in hypertension, but its association with pulse wave indices (central arterial pressure, pulse wave velocity (PWV) and augmentation index (AIx)) is poorly understood. In the present study, we assessed the degree of the effect of 24-h BPV on 24-h pulse wave indices. Brachial blood pressure was measured non-invasively over the 24 h with an electronic, oscillometric, automated device (BPLab) in 661 uncomplicated treated or untreated hypertensive patients. Digitalized oscillometric waveforms were analyzed with a validated algorithm to obtain pulse wave indices. Twenty-four-h BPV was calculated as the unweighted (SDu) or weighted s.d. (SDw) of the mean blood pressure or as the average real variability (ARV). Twenty-four-h systolic BPV showed a direct and significant relationship with the central arterial systolic pressure (r=0.28 SDu, r=0.40 SDw, r=0.34 ARV), PWV (r=0.10 SDu, r=0.21 SDw, r=0.19 ARV) and AIx (r=0.17 SDu, r=0.27 SDw, r=0.23 ARV). After adjustment for age, sex, body mass index, antihypertensive treatment and 24-h systolic blood pressure, the relationship lost some power but was still significant for all measures, except for the AIx. Pulse wave indices were higher in patients with high BPV than in those with low BPV: after adjustment, these differences were abolished for the AIx. The diastolic BPV showed a weak association with the pulse wave indices. In conclusion, in hypertensive patients, 24-h systolic BPV is moderately and independently associated with 24-h central arterial pressure and stiffness.

Energy Corner: Heat Reclamation Rescues Wasted Heat.

ERIC Educational Resources Information Center

Daugherty, Thomas

1982-01-01

Heat reclamation systems added to pre-existing central heating systems provide maximum savings at minimum cost. The benefits of a particular appliance marketed under the brand name "Energizer" are discussed. (Author/MLF)

40 CFR 89.422 - Dilute sampling procedures-CVS calibration.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Pressure depression at CVS pump inlet PPI kPa ±.055 kPa Pressure head at CVS pump outlet PPO kPa ±.055 kPa... restricted condition in an increment of pump inlet depression that will yield a minimum of six data points... depression, (kPa). (iii) The correlation function at each test point is then calculated from the calibration...

40 CFR 89.422 - Dilute sampling procedures-CVS calibration.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Pressure depression at CVS pump inlet PPI kPa ±.055 kPa Pressure head at CVS pump outlet PPO kPa ±.055 kPa... restricted condition in an increment of pump inlet depression that will yield a minimum of six data points... depression, (kPa). (iii) The correlation function at each test point is then calculated from the calibration...

40 CFR 90.424 - Dilute sampling procedures-CVS calibration.

Code of Federal Regulations, 2012 CFR

2012-07-01

.... Air temperature at CVS pump inlet PTI °C ±1.11 °C. Pressure depression at CVS pump inlet PPI kPa ±0... pump inlet depression that will yield a minimum of six data points for the total calibration. Allow the...: PB = barometric pressure, kPa PPI = Pump inlet depression, kPa. (iii) The correlation function at...

40 CFR 90.424 - Dilute sampling procedures-CVS calibration.

Code of Federal Regulations, 2014 CFR

2014-07-01

.... Air temperature at CVS pump inlet PTI °C ±1.11 °C. Pressure depression at CVS pump inlet PPI kPa ±0... pump inlet depression that will yield a minimum of six data points for the total calibration. Allow the...: PB = barometric pressure, kPa PPI = Pump inlet depression, kPa. (iii) The correlation function at...

40 CFR 90.424 - Dilute sampling procedures-CVS calibration.

Code of Federal Regulations, 2010 CFR

2010-07-01

.... Air temperature at CVS pump inlet PTI °C ±1.11 °C. Pressure depression at CVS pump inlet PPI kPa ±0... pump inlet depression that will yield a minimum of six data points for the total calibration. Allow the...: PB = barometric pressure, kPa PPI = Pump inlet depression, kPa. (iii) The correlation function at...

40 CFR 90.424 - Dilute sampling procedures-CVS calibration.

Code of Federal Regulations, 2013 CFR

2013-07-01

.... Air temperature at CVS pump inlet PTI °C ±1.11 °C. Pressure depression at CVS pump inlet PPI kPa ±0... pump inlet depression that will yield a minimum of six data points for the total calibration. Allow the...: PB = barometric pressure, kPa PPI = Pump inlet depression, kPa. (iii) The correlation function at...

40 CFR 90.424 - Dilute sampling procedures-CVS calibration.

Code of Federal Regulations, 2011 CFR

2011-07-01

.... Air temperature at CVS pump inlet PTI °C ±1.11 °C. Pressure depression at CVS pump inlet PPI kPa ±0... pump inlet depression that will yield a minimum of six data points for the total calibration. Allow the...: PB = barometric pressure, kPa PPI = Pump inlet depression, kPa. (iii) The correlation function at...

40 CFR 89.422 - Dilute sampling procedures-CVS calibration.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Pressure depression at CVS pump inlet PPI kPa ±.055 kPa Pressure head at CVS pump outlet PPO kPa ±.055 kPa... restricted condition in an increment of pump inlet depression that will yield a minimum of six data points... depression, (kPa). (iii) The correlation function at each test point is then calculated from the calibration...

40 CFR 89.422 - Dilute sampling procedures-CVS calibration.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Pressure depression at CVS pump inlet PPI kPa ±.055 kPa Pressure head at CVS pump outlet PPO kPa ±.055 kPa... restricted condition in an increment of pump inlet depression that will yield a minimum of six data points... depression, (kPa). (iii) The correlation function at each test point is then calculated from the calibration...

40 CFR 89.422 - Dilute sampling procedures-CVS calibration.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Pressure depression at CVS pump inlet PPI kPa ±.055 kPa Pressure head at CVS pump outlet PPO kPa ±.055 kPa... restricted condition in an increment of pump inlet depression that will yield a minimum of six data points... depression, (kPa). (iii) The correlation function at each test point is then calculated from the calibration...

49 CFR 178.65 - Specification 39 non-reusable (non-refillable) cylinders.

Code of Federal Regulations, 2011 CFR

2011-10-01

.... Maximum water capacity may not exceed: (i) 55 pounds (1,526 cubic inches) for a service pressure of 500 p... minimum wall thickness must be such that the wall stress at test pressure does not exceed the yield...: (1) Calculation of the stress for cylinders must be made by the following formula: S = [P(1.3D2 + 0...

49 CFR 178.39 - Specification 3BN seamless nickel cylinders.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) Type, size and service pressure. A DOT 3BN cylinder is a seamless nickel cylinder with a water capacity (nominal) not over 125 pounds water capacity (nominal) and a service pressure at least 150 to not over 500...) Wall thickness. The wall stress may not exceed 15,000 psi. A minimum wall thickness of 0.100 inch is...

49 CFR 178.39 - Specification 3BN seamless nickel cylinders.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) Type, size and service pressure. A DOT 3BN cylinder is a seamless nickel cylinder with a water capacity (nominal) not over 125 pounds water capacity (nominal) and a service pressure at least 150 to not over 500...) Wall thickness. The wall stress may not exceed 15,000 psi. A minimum wall thickness of 0.100 inch is...

40 CFR Table 3 to Subpart Ffff of... - Model Rule-Operating Limits for Incinerators and Wet Scrubbers

Code of Federal Regulations, 2010 CFR

2010-07-01

... Incinerators and Wet Scrubbers 3 Table 3 to Subpart FFFF of Part 60 Protection of Environment ENVIRONMENTAL...—Model Rule—Operating Limits for Incinerators and Wet Scrubbers As stated in § 60.3023, you must comply... units. a 2. Pressure drop across the wet scrubber or amperage to wet scrubber Minimum pressure drop or...

40 CFR Table 3 to Subpart Ffff of... - Model Rule-Operating Limits for Incinerators and Wet Scrubbers

Code of Federal Regulations, 2011 CFR

2011-07-01

... Incinerators and Wet Scrubbers 3 Table 3 to Subpart FFFF of Part 60 Protection of Environment ENVIRONMENTAL...—Model Rule—Operating Limits for Incinerators and Wet Scrubbers As stated in § 60.3023, you must comply... units. a 2. Pressure drop across the wet scrubber or amperage to wet scrubber Minimum pressure drop or...

40 CFR 86.119-90 - CVS calibration.

Code of Federal Regulations, 2014 CFR

2014-07-01

...) Pressure depression upstream of LFE EPI in. H2O (kPa) ±0.05 in. H20 (±0.012 kPa) Pressure drop across the...) ±0.5 °F (±0.3 °C) Pressure depression at CVS pump inlet PPI in. fluid (kPa) ±0.05 in. fluid (±0.022 k... depression (about 4 in. H2O (1.0 kPa) that will yield a minimum of six data points for the total calibration...

40 CFR 86.119-90 - CVS calibration.

Code of Federal Regulations, 2012 CFR

2012-07-01

...) Pressure depression upstream of LFE EPI in. H2O (kPa) ±0.05 in. H20 (±0.012 kPa) Pressure drop across the...) ±0.5 °F (±0.3 °C) Pressure depression at CVS pump inlet PPI in. fluid (kPa) ±0.05 in. fluid (±0.022 k... depression (about 4 in. H2O (1.0 kPa) that will yield a minimum of six data points for the total calibration...

40 CFR 86.119-90 - CVS calibration.

Code of Federal Regulations, 2011 CFR

2011-07-01

...) Pressure depression upstream of LFE EPI in. H2O (kPa) ±0.05 in. H20 (±0.012 kPa) Pressure drop across the...) ±0.5 °F (±0.3 °C) Pressure depression at CVS pump inlet PPI in. fluid (kPa) ±0.05 in. fluid (±0.022 k... depression (about 4 in. H2O (1.0 kPa) that will yield a minimum of six data points for the total calibration...

40 CFR 86.119-90 - CVS calibration.

Code of Federal Regulations, 2013 CFR

2013-07-01

...) Pressure depression upstream of LFE EPI in. H2O (kPa) ±0.05 in. H20 (±0.012 kPa) Pressure drop across the...) ±0.5 °F (±0.3 °C) Pressure depression at CVS pump inlet PPI in. fluid (kPa) ±0.05 in. fluid (±0.022 k... depression (about 4 in. H2O (1.0 kPa) that will yield a minimum of six data points for the total calibration...

40 CFR 86.119-90 - CVS calibration.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) Pressure depression upstream of LFE EPI in. H2O (kPa) ±0.05 in. H20 (±0.012 kPa) Pressure drop across the...) ±0.5 °F (±0.3 °C) Pressure depression at CVS pump inlet PPI in. fluid (kPa) ±0.05 in. fluid (±0.022 k... depression (about 4 in. H2O (1.0 kPa) that will yield a minimum of six data points for the total calibration...

Numerical Modeling of Surface and Volumetric Cooling using Optimal T- and Y-shaped Flow Channels

NASA Astrophysics Data System (ADS)

Kosaraju, Srinivas

2017-11-01

The layout of T- and V-shaped flow channel networks on a surface can be optimized for minimum pressure drop and pumping power. The results of the optimization are in the form of geometric parameters such as length and diameter ratios of the stem and branch sections. While these flow channels are optimized for minimum pressure drop, they can also be used for surface and volumetric cooling applications such as heat exchangers, air conditioning and electronics cooling. In this paper, an effort has been made to study the heat transfer characteristics of multiple T- and Y-shaped flow channel configurations using numerical simulations. All configurations are subjected to same input parameters and heat generation constraints. Comparisons are made with similar results published in literature.

Non-invasive positive pressure ventilation during sleep at 3800 m: Relationship to acute mountain sickness and sleeping oxyhaemoglobin saturation.

PubMed

Johnson, Pamela L; Popa, Daniel A; Prisk, G Kim; Edwards, Natalie; Sullivan, Colin E

2010-02-01

Overnight oxyhaemoglobin desaturation is related to AMS. AMS can be debilitating and may require descent. Positive pressure ventilation during sleep at high altitude may prevent AMS and therefore be useful in people travelling to high altitude, who are known to suffer from AMS. Ascent to high altitude results in hypobaric hypoxia and some individuals will develop acute mountain sickness (AMS), which has been shown to be associated with low oxyhaemoglobin saturation during sleep. Previous research has shown that positive end-expiratory pressure by use of expiratory valves in a face mask while awake results in a reduction in AMS symptoms and higher oxyhaemoglobin saturation. We aimed to determine whether positive pressure ventilation would prevent AMS by increasing oxygenation during sleep. We compared sleeping oxyhaemoglobin saturation and the incidence and severity of AMS in seven subjects sleeping for two consecutive nights at 3800 m above sea level using either non-invasive positive pressure ventilation that delivered positive inspiratory and expiratory airway pressure via a face mask, or sleeping without assisted ventilation. The presence and severity of AMS were assessed by administration of the Lake Louise questionnaire. We found significant increases in the mean and minimum sleeping oxyhaemoglobin saturation and decreases in AMS symptoms in subjects who used positive pressure ventilation during sleep. Mean and minimum sleeping SaO2 was lower in subjects who developed AMS after the night spent without positive pressure ventilation. The use of positive pressure ventilation during sleep at 3800 m significantly increased the sleeping oxygen saturation; we suggest that the marked reduction in symptoms of AMS is due to this higher sleeping SaO2. We agree with the findings from previous studies that the development of AMS is associated with a lower sleeping oxygen saturation.

Nonmonotonic pressure evolution of the upper critical field in superconducting FeSe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaluarachchi, Udhara S.; Taufour, Valentin; Böhmer, Anna E.

2016-02-01

The pressure dependence of the upper critical field, H c2,c, of single crystalline FeSe was studied using measurements of the interplane resistivity, ρ c, in magnetic fields parallel to tetragonal c axis. H c2,c(T) curves obtained under hydrostatic pressures up to 1.56 GPa, the range over which the superconducting transition temperature, T c, of FeSe exhibits a nonmonotonic dependence with local maximum at p 1 ≈ 0.8 GPa and local minimum at p 2 ≈ 1.2 GPa. The slope of the upper critical field at T c,(dH c2,c/dT)T c, also exhibits a nonmonotonic pressure dependence with distinct changes at pmore » 1 and p 2. For p < p 1 the slope can be described within a multiband orbital model. For both p 1 < p < p 2 and p > p 2 the slope is in good semiquantitative agreement with a single band, orbital Helfand-Werthamer theory with Fermi velocities determined from Shubnikov–de Haas measurements. Lastly, this finding indicates that Fermi surface changes are responsible for the local minimum of T c(p) at p 2 ≈ 1.2 GPa.« less

Laryngeal Aerodynamics in Healthy Older Adults and Adults With Parkinson's Disease.

PubMed

Matheron, Deborah; Stathopoulos, Elaine T; Huber, Jessica E; Sussman, Joan E

2017-03-01

The present study compared laryngeal aerodynamic function of healthy older adults (HOA) to adults with Parkinson's disease (PD) while speaking at a comfortable and increased vocal intensity. Laryngeal aerodynamic measures (subglottal pressure, peak-to-peak flow, minimum flow, and open quotient [OQ]) were compared between HOAs and individuals with PD who had a diagnosis of hypophonia. Increased vocal intensity was elicited via monaurally presented multitalker background noise. At a comfortable speaking intensity, HOAs and individuals with PD produced comparable vocal intensity, rates of vocal fold closure, and minimum flow. HOAs used smaller OQs, higher subglottal pressure, and lower peak-to-peak flow than individuals with PD. Both groups increased speaking intensity when speaking in noise to the same degree. However, HOAs produced increased intensity with greater driving pressure, faster vocal fold closure rates, and smaller OQs than individuals with PD. Monaural background noise elicited equivalent vocal intensity increases in HOAs and individuals with PD. Although both groups used laryngeal mechanisms as expected to increase sound pressure level, they used these mechanisms to different degrees. The HOAs appeared to have better control of the laryngeal mechanism to make changes to their vocal intensity.

Pressure-Dependent Detection of Carbon Monoxide Employing Wavelength Modulation Spectroscopy Using a Herriott-Type Cell.

PubMed

Li, Chuanliang; Wu, Yingfa; Qiu, Xuanbing; Wei, Jilin; Deng, Lunhua

2017-05-01

Wavelength modulation spectroscopy (WMS) combined with a multipass absorption cell has been used to measure a weak absorption line of carbon monoxide (CO) at 1.578 µm. A 0.95m Herriott-type cell provides an effective absorption path length of 55.1 m. The WMS signals from the first and second harmonic output of a lock-in amplifier (WMS-1 f and 2 f, respectively) agree with the Beer-Lambert law, especially at low concentrations. After boxcar averaging, the minimum detection limit achieved is 4.3 ppm for a measurement time of 0.125 s. The corresponding normalized detection limit is 84 ppm m Hz -1/2 . If the integrated time is increased to 88 s, the minimum detectable limit of CO can reach to 0.29 ppm based on an Allan variation analysis. The pressure-dependent relationship is validated after accounting for the pressure factor in data processing. Finally, a linear correlation between the WMS-2 f amplitudes and gas concentrations is obtained at concentration ratios less than 15.5%, and the accuracy is better than 92% at total pressure less than 62.7 Torr.

Psycho-Physiological Responses by Listening to Some Sounds from Our Daily Life

NASA Astrophysics Data System (ADS)

Sakamoto, H.; Hayashi, F.; Tsujikawa, M.; Sugiura, S.

1997-08-01

This study was made to clarify the relationship between mode of identification, mode of emotion and physiological response to noise. Twenty-six subjects, young females, listened to six different daily sounds for 150 s through head phones. The level of sound was 60-61LAcq. The pulse wave and blood pressure were observed, and pulse wave interval, wave height and maximum and minimum blood pressures were measured. Measurements were taken twice once 30 s before listening and again during the final 30 s of listening. The ratio of the latter value to the former value was used as the index for the evaluation of change. Immediately after the listening session, identification of the sound source and emotional response were surveyed via a questionnaire and the sounds were judged as related to comfort or discomfort. In the case of incorrect identification, physiological functions were not seen to change significantly. However, in the case of correct identification, maximum and minimum blood pressures were significantly increased form the pre-listening values. The physiological functions of the discomfort group did not change significantly. In the comfort group, wave height was decreased and blood pressure was significantly elevated.

Physical Training, Hemodynamic Parameters and Arterial Stiffness: Friends or Foes of the Hypertensive Patient?

PubMed

Iurciuc, Stela; Avram, Claudiu; Turi, Vladiana; Militaru, Anda; Avram, Adina; Cimpean, Anca Maria; Iurciuc, Mircea

2016-01-01

To evaluate the impact of physical training on central hemodynamic parameters and elasticity of large arteries in hypertensive patients. A total of 129 hypertensive patients were divided into two groups: group A followed lifestyle changes and physical training; and group B acted as a control group; seven parameters were recorded: Pulse wave velocity (PWVao), systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP), central aortic systolic blood pressure (SBPao), aortic diastolic blood pressure (DBPao), and central aortic pulse pressure (PPao). The difference between values at 4 months and baseline (Δ) were as follows: ΔPWVao was -1.02 m/s (p<0.001) versus 0.17 m/s (p=0.035), ΔSBPao was -9.6 mmHg (p=0.009) versus 1.6 mmHg (p=0.064), and ΔPPao was -6.8 mmHg (p<0.001) versus 3.2 mmHg, (p=0.029) in group A versus B, respectively. Exercise training improves SBP, PP, SBPao, PPao and may delay arterial ageing. Copyright © 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Optimization of fixed-range trajectories for supersonic transport aircraft

NASA Astrophysics Data System (ADS)

Windhorst, Robert Dennis

1999-11-01

This thesis develops near-optimal guidance laws that generate minimum fuel, time, or direct operating cost fixed-range trajectories for supersonic transport aircraft. The approach uses singular perturbation techniques to time-scale de-couple the equations of motion into three sets of dynamics, two of which are analyzed in the main body of this thesis and one of which is analyzed in the Appendix. The two-point-boundary-value-problems obtained by application of the maximum principle to the dynamic systems are solved using the method of matched asymptotic expansions. Finally, the two solutions are combined using the matching principle and an additive composition rule to form a uniformly valid approximation of the full fixed-range trajectory. The approach is used on two different time-scale formulations. The first holds weight constant, and the second allows weight and range dynamics to propagate on the same time-scale. Solutions for the first formulation are only carried out to zero order in the small parameter, while solutions for the second formulation are carried out to first order. Calculations for a HSCT design were made to illustrate the method. Results show that the minimum fuel trajectory consists of three segments: a minimum fuel energy-climb, a cruise-climb, and a minimum drag glide. The minimum time trajectory also has three segments: a maximum dynamic pressure ascent, a constant altitude cruise, and a maximum dynamic pressure glide. The minimum direct operating cost trajectory is an optimal combination of the two. For realistic costs of fuel and flight time, the minimum direct operating cost trajectory is very similar to the minimum fuel trajectory. Moreover, the HSCT has three local optimum cruise speeds, with the globally optimum cruise point at the highest allowable speed, if range is sufficiently long. The final range of the trajectory determines which locally optimal speed is best. Ranges of 500 to 6,000 nautical miles, subsonic and supersonic mixed flight, and varying fuel efficiency cases are analyzed. Finally, the payload-range curve of the HSCT design is determined.

Enhanced pressure in the central retinal vein decreases the perfusion pressure in the prelaminar region of the optic nerve head.

PubMed

Stodtmeister, Richard; Ventzke, Sylvana; Spoerl, Eberhard; Boehm, Andreas G; Terai, Naim; Haustein, Michael; Pillunat, Lutz E

2013-07-12

The pressure in the central retinal vein (CRVP) has been shown to be higher in glaucoma patients than in controls. Until now, these measurements have been performed in arbitrary units or in units of ophthalmodynamometric force. In our study, a contact lens dynamometer, calibrated in mm Hg, was used to calculate the retinal perfusion pressure. A total of 27 patients with primary open angle glaucoma (POAG) and 27 healthy control subjects were included in the study. The IOP measurement included Goldmann applanation tonometry, whereas the pressure enhancement measurement consisted of contact lens dynamometry. results: the pressures are given in mm hg, and are expressed as the mean ± SD for the control subjects versus the POAG patients: IOP 14.4 ± 2.7 vs. 15.4 ± 2.9, systolic blood pressure 141 ± 20.1 vs. 153 ± 16.5 (P = 0.013), central retinal vein threshold pressure (CRVTP) 11.9 ± 3.8 vs. 16.8 ± 5.0, CRVP 15.0 ± 2.7 vs. 17.9 ± 4.2, and retinal perfusion pressure (PPret) standard 84 ± 12.2 vs. 94 ± 9.1 and new 83 ± 12.2 vs. 91 ± 9.6. The differences in PPret between using the new versus the standard method are 0.55 ± 1.33 vs. -2.5 ± 3.89 (P = 0.041 and P = 0.002, respectively). The PPret was at least 5.0 mm Hg lower in 5 of the 27 POAG patients when the new calculation method was used. The perfusion pressure in the retina and prelaminar region of the optic nerve head (ONH) may be lower than expected because the CRVP may be higher. The pressure measurement in the central retinal vein may be a step toward a better understanding of ONH pathophysiology.

A Prospective International Multicentre Cohort Study of Intraoperative Heart Rate and Systolic Blood Pressure and Myocardial Injury After Noncardiac Surgery: Results of the VISION Study

PubMed Central

Abbott, Tom E. F.; Pearse, Rupert M.; Archbold, R. Andrew; Ahmad, Tahania; Niebrzegowska, Edyta; Wragg, Andrew; Rodseth, Reitze N.; Devereaux, Philip J.

2018-01-01

BACKGROUND: The association between intraoperative cardiovascular changes and perioperative myocardial injury has chiefly focused on hypotension during noncardiac surgery. However, the relative influence of blood pressure and heart rate (HR) remains unclear. We investigated both individual and codependent relationships among intraoperative HR, systolic blood pressure (SBP), and myocardial injury after noncardiac surgery (MINS). METHODS: Secondary analysis of the Vascular Events in Noncardiac Surgery Cohort Evaluation (VISION) study, a prospective international cohort study of noncardiac surgical patients. Multivariable logistic regression analysis tested for associations between intraoperative HR and/or SBP and MINS, defined by an elevated serum troponin T adjudicated as due to an ischemic etiology, within 30 days after surgery. Predefined thresholds for intraoperative HR and SBP were: maximum HR >100 beats or minimum HR <55 beats per minute (bpm); maximum SBP >160 mm Hg or minimum SBP <100 mm Hg. Secondary outcomes were myocardial infarction and mortality within 30 days after surgery. RESULTS: After excluding missing data, 1197 of 15,109 patients (7.9%) sustained MINS, 454 of 16,031 (2.8%) sustained myocardial infarction, and 315 of 16,061 patients (2.0%) died within 30 days after surgery. Maximum intraoperative HR >100 bpm was associated with MINS (odds ratio [OR], 1.27 [1.07–1.50]; P < .01), myocardial infarction (OR, 1.34 [1.05–1.70]; P = .02), and mortality (OR, 2.65 [2.06–3.41]; P < .01). Minimum SBP <100 mm Hg was associated with MINS (OR, 1.21 [1.05–1.39]; P = .01) and mortality (OR, 1.81 [1.39–2.37]; P < .01), but not myocardial infarction (OR, 1.21 [0.98–1.49]; P = .07). Maximum SBP >160 mm Hg was associated with MINS (OR, 1.16 [1.01–1.34]; P = .04) and myocardial infarction (OR, 1.34 [1.09–1.64]; P = .01) but, paradoxically, reduced mortality (OR, 0.76 [0.58–0.99]; P = .04). Minimum HR <55 bpm was associated with reduced MINS (OR, 0.70 [0.59–0.82]; P < .01), myocardial infarction (OR, 0.75 [0.58–0.97]; P = .03), and mortality (OR, 0.58 [0.41–0.81]; P < .01). Minimum SBP <100 mm Hg with maximum HR >100 bpm was more strongly associated with MINS (OR, 1.42 [1.15–1.76]; P < .01) compared with minimum SBP <100 mm Hg alone (OR, 1.20 [1.03–1.40]; P = .02). CONCLUSIONS: Intraoperative tachycardia and hypotension are associated with MINS. Further interventional research targeting HR/blood pressure is needed to define the optimum strategy to reduce MINS. PMID:29077608

Bilateral widespread mechanical pain sensitivity in carpal tunnel syndrome: evidence of central processing in unilateral neuropathy.

PubMed

Fernández-de-las-Peñas, César; de la Llave-Rincón, Ana Isabel; Fernández-Carnero, Josué; Cuadrado, María Luz; Arendt-Nielsen, Lars; Pareja, Juan A

2009-06-01

The aim of this study was to investigate whether bilateral widespread pressure hypersensitivity exists in patients with unilateral carpal tunnel syndrome. A total of 20 females with carpal tunnel syndrome (aged 22-60 years), and 20 healthy matched females (aged 21-60 years old) were recruited. Pressure pain thresholds were assessed bilaterally over median, ulnar, and radial nerve trunks, the C5-C6 zygapophyseal joint, the carpal tunnel and the tibialis anterior muscle in a blinded design. The results showed that pressure pain threshold levels were significantly decreased bilaterally over the median, ulnar, and radial nerve trunks, the carpal tunnel, the C5-C6 zygapophyseal joint, and the tibialis anterior muscle in patients with unilateral carpal tunnel syndrome as compared to healthy controls (all, P < 0.001). Pressure pain threshold was negatively correlated to both hand pain intensity and duration of symptoms (all, P < 0.001). Our findings revealed bilateral widespread pressure hypersensitivity in subjects with carpal tunnel syndrome, which suggest that widespread central sensitization is involved in patients with unilateral carpal tunnel syndrome. The generalized decrease in pressure pain thresholds associated with pain intensity and duration of symptoms supports a role of the peripheral drive to initiate and maintain central sensitization. Nevertheless, both central and peripheral sensitization mechanisms are probably involved at the same time in carpal tunnel syndrome.

Pressure-enhanced ortho-para conversion in solid hydrogen up to 58 GPa

PubMed Central

Eggert, Jon H.; Karmon, Eran; Hemley, Russell J.; Mao, Ho-kwang; Goncharov, Alexander F.

1999-01-01

We measured the ortho-para conversion rate in solid hydrogen by using Raman scattering in a diamond-anvil cell, extending previous measurements by a factor of 60 in pressure. We confirm previous experiments that suggested a decrease in the conversion rate above about 0.5 GPa. We observe a distinct minimum at 3 GPa followed by a drastic increase in the conversion rate to our maximum pressure of 58 GPa. This pressure enhancement of conversion is not predicted by previous theoretical treatments and must be due to a new conversion pathway. PMID:10535910

Forensic Science

ERIC Educational Resources Information Center

Cobb, P. G. W.

1973-01-01

Summarizes the type of work carried out by forensic chemists and the minimum qualification needed for appointment. Indicates that there are eight Home Office regional forensic science laboratories in addition to the Central Research Establishment at Aldermaston. (CC)

Comparison of Central Corneal Thickness Between Fourier-Domain OCT, Very High-Frequency Digital Ultrasound, and Scheimpflug Imaging Systems.

PubMed

Yap, Timothy E; Archer, Timothy J; Gobbe, Marine; Reinstein, Dan Z

2016-02-01

To compare corneal thickness measurements between three imaging systems. In this retrospective study of 81 virgin and 58 post-laser refractive surgery corneas, central and minimum corneal thickness were measured using optical coherence tomography (OCT), very high-frequency digital ultrasound (VHF digital ultrasound), and a Scheimpflug imaging system. Agreement between methods was analyzed using mean differences (bias) (OCT - VHF digital ultrasound, OCT - Scheimpflug, VHF digital ultrasound - Scheimpflug) and Bland-Altman analysis with 95% limits of agreement (LoA). Virgin cornea mean central corneal thickness was 508.3 ± 33.2 µm (range: 434 to 588 µm) for OCT, 512.7 ± 32.2 µm (range: 440 to 587 µm) for VHF digital ultrasound, and 530.2 ± 32.6 µm (range: 463 to 612 µm) for Scheimpflug imaging. OCT and VHF digital ultrasound showed the closest agreement with a bias of -4.37 µm, 95% LoA ±12.6 µm. Least agreement was between OCT and Scheimpflug imaging with a bias of -21.9 µm, 95% LoA ±20.7 µm. Bias between VHF digital ultrasound and Scheimpflug imaging was -17.5 µm, 95% LoA ±19.0 µm. In post-laser refractive surgery corneas, mean central corneal thickness was 417.9 ± 47.1 µm (range: 342 to 557 µm) for OCT, 426.3 ± 47.1 µm (range: 363 to 563 µm) for VHF digital ultrasound, and 437.0 ± 48.5 µm (range: 359 to 571 µm) for Scheimpflug imaging. Closest agreement was between OCT and VHF digital ultrasound with a bias of -8.45 µm, 95% LoA ±13.2 µm. Least agreement was between OCT and Scheimpflug imaging with a bias of -19.2 µm, 95% LoA ±19.2 µm. Bias between VHF digital ultrasound and Scheimpflug imaging was -10.7 µm, 95% LoA ±20.0 µm. No relationship was observed between difference in central corneal thickness measurements and mean central corneal thickness. Results were similar for minimum corneal thickness. Central and minimum corneal thickness was measured thinnest by OCT and thickest by Scheimpflug imaging in both groups. A clinically significant bias existed between Scheimpflug imaging and the other two modalities. Copyright 2016, SLACK Incorporated.

Glottal volume velocity waveform characteristics in subjects with and without vocal training, related to gender, sound intensity, fundamental frequency, and age.

PubMed

Sulter, A M; Wit, H P

1996-11-01

Glottal volume velocity waveform characteristics of 224 subjects, categorized in four groups according to gender and vocal training, were determined, and their relations to sound-pressure level, fundamental frequency, intra-oral pressure, and age were analyzed. Subjects phonated at three intensity conditions. The glottal volume velocity waveforms were obtained by inverse filtering the oral flow. Glottal volume velocity waveforms were parameterized with flow-based (minimum flow, ac flow, average flow, maximum flow declination rate) and time-based parameters (closed quotient, closing quotient, speed quotient), as well as with derived parameters (vocal efficiency and glottal resistance). Higher sound-pressure levels, intra-oral pressures, and flow-parameter values (ac flow, maximum flow declination rate) were observed, when compared with previous investigations. These higher values might be the result of the specific phonation tasks (stressed /ae/ vowel in a word and a sentence) or filtering processes. Few statistically significant (p < 0.01) differences in parameters were found between untrained and trained subjects [the maximum flow declination rate and the closing quotient were higher in trained women (p < 0.001), and the speed quotient was higher in trained men (p < 0.005)]. Several statistically significant parameter differences were found between men and women [minimum flow, ac flow, average flow, maximum flow declination rate, closing quotient, glottal resistance (p < 0.001), and closed quotient (p < 0.005)]. Significant effects of intensity condition were observed on ac flow, maximum flow declination rate, closing quotient, and vocal efficiency in women (p < 0.005), and on minimum flow, ac flow, average flow, maximum flow declination rate, closed quotient, and vocal efficiency in men (p < 0.01).

14 CFR 29.1323 - Airspeed indicating system.

Code of Federal Regulations, 2010 CFR

2010-01-01

... minimum practicable instrument calibration error when the corresponding pitot and static pressures are... pitot tube or an equivalent means of preventing malfunction due to icing. [Doc. No. 5084, 29 FR 16150...

Impact of statin therapy on central aortic pressures and hemodynamics: principal results of the Conduit Artery Function Evaluation-Lipid-Lowering Arm (CAFE-LLA) Study.

PubMed

Williams, Bryan; Lacy, Peter S; Cruickshank, J Kennedy; Collier, David; Hughes, Alun D; Stanton, Alice; Thom, Simon; Thurston, Herbert

2009-01-06

Statins reduce the risk of cardiovascular events in people with hypertension. This benefit could arise from a beneficial effect of statins on central aortic pressures and hemodynamics. The Conduit Artery Function Evaluation-Lipid-Lowering Arm (CAFE-LLA) study, an Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT) substudy, investigated this hypothesis in a prospective placebo-controlled study of treated patients with hypertension. CAFE-LLA recruited 891 patients randomized to atorvastatin 10 mg/d or placebo from 5 centers in the United Kingdom and Ireland. Radial artery applanation tonometry and pulse-wave analysis were used to derive central aortic pressures and hemodynamic indices at repeated visits over 3.5 years of follow-up. Atorvastatin lowered low-density lipoprotein cholesterol by 32.4 mg/dL (95% confidence interval [CI], 28.6 to 36.3) and total cholesterol by 35.1 mg/dL (95% confidence interval, 30.9 to 39.4) relative to placebo. Time-averaged brachial blood pressure was similar in CAFE-LLA patients randomized to atorvastatin or placebo (change in brachial systolic blood pressure, -0.1 mm Hg [95% CI, -1.8 to 1.6], P=0.9; change in brachial pulse pressure, -0.02 mm Hg [95% CI, -1.6 to 1.6], P=0.9). Atorvastatin did not influence central aortic pressures (change in aortic systolic blood pressure, -0.5 mm Hg [95% CI, -2.3 to 1.2], P=0.5; change in aortic pulse pressure, -0.4 mm Hg [95% CI, -1.9 to 1.0], P=0.6) and had no influence on augmentation index (change in augmentation index, -0.4%; 95% CI, -1.7 to 0.8; P=0.5) or heart rate (change in heart rate, 0.25 bpm; 95% CI, -1.3 to 1.8; P=0.7) compared with placebo. The effect of statin or placebo therapy was not modified by the blood pressure-lowering treatment strategy in the factorial design. Statin therapy sufficient to significantly reduce cardiovascular events in treated hypertensive patients in ASCOT did not influence central aortic blood pressure or hemodynamics in a large representative cohort of ASCOT patients in CAFE-LLA.

US Army Institute of Surgical Research Annual Research Progress Report FY 1982.

DTIC Science & Technology

1982-10-01

arterial blood gases, respiratory rate, daily chest roentgenograms), cardiovascular (blood pressure, central venous pressure, cardiac output measured...confirmed by the finding that central venous plasma histamine rose from 3.79 + 0.86 to 77.58 + 27.28 and 74.22 + 32.79 ng/ml at one and two minutes postburn...wounds at 2 - 4 weeks after injury. Central venous indwelling catheters were placed via the right jugular vein on the day prior to use as previously

The association of nonalcoholic fatty liver disease with central and peripheral blood pressure in adolescence: findings from a cross-sectional study

PubMed Central

Patel, Sumaiya; Lawlor, Debbie A.; Ferreira, Diana L.S.; Hughes, Alun D.; Chaturvedi, Nish; Callaway, Mark; Day, Chris; Sattar, Naveed; Fraser, Abigail

2015-01-01

Objectives: We aimed to determine the association of nonalcoholic fatty liver disease (NAFLD) with central and peripheral blood pressure (BP), in a general adolescent population and to examine whether associations are independent of adiposity. Methods: Using cross-sectional data from a subsample (N = 1904) of a UK birth cohort, we assessed markers of NAFLD including ultrasound scan (USS) determined fatty liver, shear velocity (marker of liver fibrosis), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyltransferase (GGT) at a mean age of 17.8 years. These were related to BP [central and peripheral SBP and DBP and mean arterial pressure (MAP)]. Results: Fatty liver was positively associated with central and peripheral SBP, DBP and MAP in models adjusting for age, sex, social class, puberty and alcohol intake. These positive associations were attenuated to the null when fat mass was included. For example, in confounder-adjusted models, not including fat mass, mean central SBP was 3.74 mmHg [95% confidence interval (CI) 1.12 to 6.36] higher in adolescents with USS fatty liver than in those without; with additional adjustment for fat mass, the association attenuated to the null value (−0.37 mmHg; 95% CI –3.09 to 2.36). Similar patterns were found for associations of ALT and GGT with central and peripheral BP. There was no consistent evidence of associations of shear velocity or AST with BP measurements. Fatty liver was not consistently associated with central pulse pressure (PP), peripheral PP and Aix@75. Conclusion: NAFLD is not associated with higher central or peripheral BP in adolescents once confounding by adiposity is taken into account. PMID:25426570

Baseline aortic pulse wave velocity is associated with central and peripheral pressor responses during the cold pressor test in healthy subjects.

PubMed

Borner, Anastasiya; Murray, Kyle; Trotter, Claire; Pearson, James

2017-07-01

Cold environmental temperatures increase sympathetic nerve activity and blood pressure, and increase the risk of acute cardiovascular events in aged individuals. The acute risk of cardiovascular events increases with aortic pulse wave velocity as well as elevated central and peripheral pulse pressures. The aim of this study was to examine the independent influence of aortic pulse wave velocity upon central and peripheral pressor responses to sympathetic activation via the cold pressor test (CPT). Twenty-two healthy subjects (age: 18-73 years) completed a CPT with the left hand immersed in 2-4°C water for 3 min. During the CPT, central (from: 36 ± 7 to: 51 ± 12 mmHg) and peripheral pulse pressure increased (from: 54 ± 7 to: 66 ± 11; both P  <   0.05). In all subjects the increase in central pulse pressure during the CPT was independently associated with baseline aortic pulse wave velocity ( r 2  = 0.221, P  =   0.027) but not age ( P  >   0.05). In a subset of subjects with higher arterial stiffness, the increase in peripheral pulse pressure during the CPT was independently associated with baseline aortic pulse wave velocity ( r 2  = 0.415, P  =   0.032) but not age ( P  >   0.05). These data indicate that central and peripheral pulse pressure responses during sympathetic activation are positively and independently associated with aortic pulse wave velocity through a wide age range. Decreasing aortic pulse wave velocity in aged individuals with elevated arterial stiffness may help reduce the incidence of acute cardiovascular events upon exposure to cold environmental temperatures. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

High-pressure destruction kinetics of Clostridium sporogenes spores in ground beef at elevated temperatures.

PubMed

Zhu, Songming; Naim, Fadia; Marcotte, Michèle; Ramaswamy, Hosahalli; Shao, Yanwen

2008-08-15

High pressure (HP) is an alternative technique for thermal sterilization of foods with minimum quality loss. HP destruction kinetics of bacterial spores is essential to establishing sterilization process, but knowledge in this field is still very limited. In this study, destruction kinetics was investigated using Clostridium sporogenes PA 3679 (ATCC7955) spores in extra-lean ground beef (5 g each sealed in a sterile plastic bag). Duplicated samples were subjected to HP treatments at 700, 800 and 900 MPa in a HP system equipped with a Polyoxymethylene insulator to maintain constant temperatures at 80, 90 and 100 degrees C during pressure-holding time. The kinetic parameters of the spores (D- and Z-values) were evaluated at these pressures and temperatures. For the pressure from 700 to 900 MPa, D-values ranged from 15.8 to 7.0 and 1.5 to 0.63 min at 80 and 100 degrees C, respectively. The pressure resistance of Z(T)(P) value was 520-563 MPa at 80-100 degrees C. The temperature resistance of Z(P)(T) value was 19.1-19.7 degrees C at 700-900 MPa, much higher than that at atmospheric condition (12.4 degrees C). A regression model was generated which can be used to predict D-value or the death time of a minimum process under given pressure and temperature conditions. HP treatment with elevated temperatures can destroy bacterial spores with a shorter time or lower temperature than conventional thermal processing. This study provides useful information for the achievement of a safe HP sterilization process.

Assessment of central haemomodynamics from a brachial cuff in a community setting

PubMed Central

2012-01-01

Background Large artery stiffening and wave reflections are independent predictors of adverse events. To date, their assessment has been limited to specialised techniques and settings. A new, more practical method allowing assessment of central blood pressure from waveforms recorded using a conventional automated oscillometric monitor has recently been validated in laboratory settings. However, the feasibility of this method in a community based setting has not been assessed. Methods One-off peripheral and central haemodynamic (systolic and diastolic blood pressure (BP) and pulse pressure) and wave reflection parameters (augmentation pressure (AP) and index, AIx) were obtained from 1,903 volunteers in an Austrian community setting using a transfer-function like method (ARCSolver algorithm) and from waveforms recorded with a regular oscillometric cuff. We assessed these parameters for known differences and associations according to gender and age deciles from <30 years to >80 years in the whole population and a subset with a systolic BP < 140 mmHg. Results We obtained 1,793 measures of peripheral and central BP, PP and augmentation parameters. Age and gender associations with central haemodynamic and augmentation parameters reflected those previously established from reference standard non-invasive techniques under specialised settings. Findings were the same for patients with a systolic BP below 140 mmHg (i.e. normotensive). Lower values for AIx in the current study are possibly due to differences in sampling rates, detection frequency and/or averaging procedures and to lower numbers of volunteers in younger age groups. Conclusion A novel transfer-function like algorithm, using brachial cuff-based waveform recordings, provides robust and feasible estimates of central systolic pressure and augmentation in community-based settings. PMID:22734820

Hypertension in the US Black population: risk factors, complications, and potential impact of central aortic pressure on effective treatment.

PubMed

Ferdinand, Keith C; Townsend, Raymond R

2012-04-01

The identification of specific factors that contribute to hypertension development and progression among blacks in the US is the focus of much ongoing research. The purpose of this paper is to review these factors and discuss how they present unique opportunities for improving the management of hypertension in this difficult-to-treat population. We searched the published literature for articles discussing the risk factors for hypertension and cardiovascular disease in blacks; the target-organ damage and cardiovascular complications associated with hypertension in this difficult-to-treat population; and the role of central blood pressure in predicting cardiovascular events. The prevalence of hypertension is higher in blacks than in other race/ethnic groups, with environmental and genetic risk factors likely playing an important role. The cardiovascular and renal consequences of hypertension (eg, left ventricular hypertrophy and renal failure) are also greater in blacks relative to their white counterparts. Preliminary data suggest that central blood pressure may be higher in blacks than in whites and has the potential for greater prognostic capability relative to peripheral blood pressure. There is an urgent need to successfully control hypertension in the black population. Although data are limited in blacks, evidence suggests that central blood pressure warrants more continued assessment in future clinical studies.

Optimization of micromachined membrane switches

NASA Astrophysics Data System (ADS)

Hiltmann, Kai; Lang, Walter

1997-09-01

We have determined the minimum dimensions for micromachined membrane switches in several experiments, both regarding the strength of the membranes themselves and the elongations required for safe switching performance. Based on these data, pressure switches for voltages of 10 - 100 V were made as single and multiple elements and tested. Test results, with scatter of pressure threshold data in the ten per cent range, prove very encouraging for further development.

75 FR 57830 - Office of Hazardous Materials Safety; Notice of Applications for Modification of Special Permit

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-22

...) the minimum Corporation), burst pressure to 86.18 Haryana. bar (1250PSIG); change paragraph 7.(2)(l) hydrostatic test pressure 34.74 bar to (500 PSIG) instead of 34.74 bar (500); and add a new drawing. 12629-M... lieu of hydrostatic testing. 12706-M RAGASCO Raufoss.... 49 CFR 173.34; To modify the special 173.201...

Directed spray mast

DOEpatents

Nance, Thomas A.; Siddall, Alvin A.; Cheng, William Y.; Counts, Kevin T.

2005-05-10

Disclosed is an elongated, tubular, compact high pressure sprayer apparatus for insertion into an access port of vessels having contaminated interior areas that require cleaning by high pressure water spray. The invention includes a spray nozzle and a camera adjacent thereto with means for rotating and raising and lowering the nozzle so that areas identified through the camera may be cleaned with a minimum production of waste water to be removed.

42 CFR 84.201 - Head harnesses; minimum requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... of pressure over the entire area in contact with the face. (2) Facepieces for single-use vinyl... face. (b) Mouthpieces shall be equipped where applicable, with an adjustable and replaceable harness...

Experimental and numeric investigation of Impella pumps as cavopulmonary assistance for a failing Fontan.

PubMed

Haggerty, Christopher M; Fynn-Thompson, Francis; McElhinney, Doff B; Valente, Anne Marie; Saikrishnan, Neelakantan; Del Nido, Pedro J; Yoganathan, Ajit P

2012-09-01

This study sought to evaluate the performance of microaxial ventricular assist devices for the purposes of supporting failing Fontan physiology by decreasing central venous pressure. Three Abiomed Impella pumps (Abiomed, Inc, Danvers, Mass) were evaluated in a mock circulatory system of the Fontan circuit. The local response of pressures and flows to pump function was assessed as a function of pump speed and pulmonary vascular resistance at a high baseline central venous pressure. For one device, subsequent modeling studies were conducted using a lumped parameter model of the single ventricle circuit. The left ventricular devices (Impella 2.5, 5.0) were shown to be suboptimal as single device solutions for cavopulmonary support. The small area of these devices relative to vessel diameter led to significant flow recirculation without an obstructive separator in place. Furthermore, downstream pressure augmentation adversely affected the pressure in the superior vena cava. The use of 2 devices would be mandatory for successful support. The right-sided device (Impella RP), whose outflow was positioned in the left pulmonary artery, demonstrated decreased flow recirculation and did not impede superior caval venous flow. Although static pressure is still required to drive flow through the opposite lung, numeric modeling demonstrated the potential for modest but significant improvements in lowering the central venous pressure (2-8 mm Hg). Left-sided microaxial pumps are not well suited for cavopulmonary support because of severe flow recirculation and the need for multiple devices. The right-ventricular Impella device provides improved performance by directing flow into the pulmonary artery, resulting in modest decreases in central venous pressure. Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Arterial Wave Reflection and Aortic Valve Calcification in an Elderly Community-Based Cohort

PubMed Central

Sera, Fusako; Russo, Cesare; Iwata, Shinichi; Jin, Zhezhen; Rundek, Tatjana; Elkind, Mitchell S.V.; Homma, Shunichi; Sacco, Ralph L.; Di Tullio, Marco R.

2015-01-01

Background Aortic valve calcification (AVC) without stenosis is common in the elderly, is associated with cardiovascular morbidity and mortality, and may progress to aortic valve stenosis. Arterial stiffness and pulse wave reflection are important components of proximal aortic hemodynamics, but their relationship with AVC is not established. Methods To investigate the relationship of arterial wave reflection and stiffness with AVC, pulse wave analysis and AVC evaluation by echocardiography were performed in 867 participants from the Cardiovascular Abnormalities and Brain Lesions (CABL) study. Participants were divided into 4 categories based on the severity and extent of AVC: 1) none or mild focal AVC; 2) mild diffuse AVC; 3) moderate-severe focal AVC; and 4) moderate-severe diffuse AVC. Central blood pressures and pulse pressure, total arterial compliance, augmentation index, and time to wave reflection were assessed using applanation tonometry. Results Indicators of arterial stiffness and wave reflection were significantly associated with AVC severity, except for central systolic and diastolic pressures and time to reflection. After adjustment for pertinent covariates (age, sex, race/ethnicity, and eGFR), only augmentation pressure (P = .02) and augmentation index (P = .002) were associated with the severity of AVC. Multivariable logistic regression analysis revealed that augmentation pressure (odds ratio per mmHg = 1.14; 95% confidence interval, 1.02–1.27; P = .02) and augmentation index (odds ratio per percentage point = 1.07; 95% confidence interval, 1.01–1.13; P = .02) were associated with an increase risk of moderate-severe diffuse AVC, even when central blood pressure value was included in the same model. Conclusions Arterial wave reflection is associated with AVC severity, independent of blood pressure values. Increased contribution of wave reflection to central blood pressure could be involved in the process leading to AVC. PMID:25600036

The Speed of Axial Propagation of a Cylindrical Bubble Through a Cylindrical Vortex

NASA Technical Reports Server (NTRS)

Shariff, Karim; Mansour, Nagi N. (Technical Monitor)

2002-01-01

Inspired by the rapid elongation of air columns injected into vortices by dolphins, we present an exact inviscid solution for the axial speed (assumed steady) of propagation of the tip of a semi-infinite cylindrical bubble along the axis of a cylindrical vortex. The bubble is assumed to be held at constant pressure by being connected to a reservoir, the lungs of the dolphin, say. For a given bubble pressure, there is a modest critical rotation rate above which steadily propagating bubbles exist. For a bubble at ambient pressure, the propagation speed of the bubble (relative to axial velocity within the vortex) varies between 0.5 and 0.6 of the maximum rotational speed of the vortex. Surprisingly, the bubble tip can propagate (almost as rapidly) even when the pressure minimum in the vortex core is greater than the bubble pressure; in this case, solutions exhibit a dimple on the nose of the bubble. A situation important for incipient vortex cavitation, and one which dolphins also demonstrate, is elongation of a free bubble, i.e., one whose internal pressure may vary. Under the assumption that the acceleration term is small (checked a posteriori), the steady solution is applied at each instant during the elongation. Three types of behavior are then possible depending on physical parameters and initial conditions: (A) Unabated elongation with slowly increasing bubble pressure, and nearly constant volume. Volume begins to decrease in the late stages. (B1) Elongation with decreasing bubble pressure. A limit point of the steady solution is encountered at a finite bubble length. (B2) Unabated elongation with decreasing bubble pressure and indefinite creation of volume. This is made possible by the existence of propagating solutions at bubble pressures below the minimum vortex pressure. As the bubble stretches, its radius initially decreases but then becomes constant; this is also observed in experiments on incipient vortex cavitation.

Age and sex-specific associations of anthropometric measures of adiposity with blood pressure and hypertension in India: a cross-sectional study.

PubMed

Taing, Kevin Y; Farkouh, Michael E; Moineddin, Rahim; Tu, Jack V; Jha, Prabhat

2016-12-01

A determinant of blood pressure is adiposity; however, there are uncertainties surrounding whether general or central adiposity is the more important determinant of blood pressure. Further, inconsistent results exist for the relationships of anthropometric measures with blood pressure and hypertension, and whether these relationships differ substantially by age and sex is unclear. We aimed to elucidate the associations of anthropometric measures of general and central adiposity with blood pressure and hypertension, and determine the effect of age and sex on these relationships. We used cross-sectional data from the Centre for Global Health Research health check-up survey conducted during 2006-2007 of the general population in India (n = 7 601; age 18-59 years). We examined the associations of anthropometric measures (body mass index, waist circumference, hip circumference, waist-hip ratio, waist-height ratio) with blood pressure components (systolic pressure, diastolic pressure, pulse pressure, mean arterial pressure, mid-blood pressure) and hypertension within four (18-29 years, 30-39 years, 40-49 years, 50-59 years) age groups, by sex. We adjusted all analyses for education and location, with further adjustments, variously, for either a measure of central (waist circumference) or general (body mass index) adiposity. On average, every 5 kg/m 2 greater body mass index or 10 cm wider waist circumference was associated with a 5 and 4 mmHg higher systolic blood pressure, respectively. When considered separately, each anthropometric measure was strongly and positively associated with most blood pressure components in all age groups, and for both sexes. However, with few exceptions, when considered jointly (body mass index adjusted for waist circumference), the associations of body mass index with blood pressure components and hypertension were greatly diminished for both sexes, and particularly in the ≥30 years age groups. By contrast, further adjustment of waist circumference for body mass index did not materially alter the associations of waist circumference with blood pressure components and hypertension. Our findings indicate that central adiposity, as assessed with anthropometric measures, may be a more important determinant of blood pressure and hypertension than general adiposity for adults in India.

Xylem resistance to embolism: presenting a simple diagnostic test for the open vessel artefact.

PubMed

Torres-Ruiz, José M; Cochard, Hervé; Choat, Brendan; Jansen, Steven; López, Rosana; Tomášková, Ivana; Padilla-Díaz, Carmen M; Badel, Eric; Burlett, Regis; King, Andrew; Lenoir, Nicolas; Martin-StPaul, Nicolas K; Delzon, Sylvain

2017-07-01

Xylem vulnerability to embolism represents an essential trait for the evaluation of the impact of hydraulics in plant function and ecology. The standard centrifuge technique is widely used for the construction of vulnerability curves, although its accuracy when applied to species with long vessels remains under debate. We developed a simple diagnostic test to determine whether the open-vessel artefact influences centrifuge estimates of embolism resistance. Xylem samples from three species with differing vessel lengths were exposed to less negative xylem pressures via centrifugation than the minimum pressure the sample had previously experienced. Additional calibration was obtained from non-invasive measurement of embolism on intact olive plants by X-ray microtomography. Results showed artefactual decreases in hydraulic conductance (k) for samples with open vessels when exposed to a less negative xylem pressure than the minimum pressure they had previously experienced. X-Ray microtomography indicated that most of the embolism formation in olive occurs at xylem pressures below -4.0 MPa, reaching 50% loss of hydraulic conductivity at -5.3 MPa. The artefactual reductions in k induced by centrifugation underestimate embolism resistance data of species with long vessels. A simple test is suggested to avoid this open vessel artefact and to ensure the reliability of this technique in future studies. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Using Fully Coupled Hydro-Geomechanical Numerical Test Bed to Study Reservoir Stimulation with Low Hydraulic Pressure

DOE Data Explorer

Fu, Pengcheng; Johnson, Scott M.; Carrigan, Charles R.

2012-01-31

This paper documents our effort to use a fully coupled hydro-geomechanical numerical test bed to study using low hydraulic pressure to stimulate geothermal reservoirs with existing fracture network. In this low pressure stimulation strategy, fluid pressure is lower than the minimum in situ compressive stress, so the fractures are not completely open but permeability improvement can be achieved through shear dilation. We found that in this low pressure regime, the coupling between the fluid phase and the rock solid phase becomes very simple, and the numerical model can achieve a low computational cost. Using this modified model, we study the behavior of a single fracture and a random fracture network.

Acoustic and aerodynamic testing of a scale model variable pitch fan

NASA Technical Reports Server (NTRS)

Jutras, R. R.; Kazin, S. B.

1974-01-01

A fully reversible pitch scale model fan with variable pitch rotor blades was tested to determine its aerodynamic and acoustic characteristics. The single-stage fan has a design tip speed of 1160 ft/sec (353.568 m/sec) at a bypass pressure ratio of 1.5. Three operating lines were investigated. Test results show that the blade pitch for minimum noise also resulted in the highest efficiency for all three operating lines at all thrust levels. The minimum perceived noise on a 200-ft (60.96 m) sideline was obtained with the nominal nozzle. At 44% of takeoff thrust, the PNL reduction between blade pitch and minimum noise blade pitch is 1.8 PNdB for the nominal nozzle and decreases with increasing thrust. The small nozzle (6% undersized) has the highest efficiency at all part thrust conditions for the minimum noise blade pitch setting; although, the noise is about 1.0 PNdB higher for the small nozzle at the minimum noise blade pitch position.

Cork is used to make tooling patterns and molds

NASA Technical Reports Server (NTRS)

Hoffman, F. J.

1965-01-01

Sheet and waste cork are cemented together to provide a tooling pattern or mold. The cork form withstands moderately high temperatures under vacuum or pressure with minimum expansion, shrinkage, or distortion.

Heat-transfer thermal switch

NASA Technical Reports Server (NTRS)

Friedell, M. V.; Anderson, A. J.

1974-01-01

Thermal switch maintains temperature of planetary lander, within definite range, by transferring heat. Switch produces relatively large stroke and force, uses minimum electrical power, is lightweight, is vapor pressure actuated, and withstands sterilization temperatures without damage.

Influence of a high-intensity interval training session on peripheral and central blood pressure at rest and during stress testing in healthy individuals.

PubMed

Ketelhut, Sascha; Milatz, Florian; Heise, Walter; Ketelhut, Reinhard G

2016-09-01

Regular physical activity is known to reduce arterial pressure (BP). In a previous investigation, we could prove that even a single bout of moderate-intensity continuous exercise (MICE) causes a prolonged reduction in BP. Whether high-intensity interval training (HIIT) has a favourable influence on BP, and therefore may be followed subjects and methods by a prolonged BP reduction, should be examined on the basis of blood pressure response after exercise and during a subsequent stress test. In 39 healthy men (aged 34 ± 8 years, BMI 24 ± 2), peripheral and central BP were measured noninvasively at rest and at the end of a 2-min cold pressor test (CPT) using a Mobil-O-Graph (24 PWA monitor, IEM). Following HIIT (6 x 1 min at 98% of the previously determined maximum wattage, 4-min rest between intervals) BP was measured again throughout 60 min of rest and thereafter during a CPT. The results were compared with those obtained before HIIT. Similar to MICE, peripheral and central BPs were significantly (p < 0.05) lower 45 min after HIIT. When analysing peripheral BP during a CPT before and after exercise, significantly lower systolic (p < 0.001) and diastolic (p = 0.008) pressures were established after HIIT. This was true for systolic (p = 0.002) and diastolic (p = 0.006) central BP as well. Although there were no more significant differences between pressures at rest before and 60 min after exercise, the increase in peripheral systolic pressure due to CPT was significantly slower after HIIT (p = 0.019) when compared with BP during CPT before exercise. This was true for central systolic BP as well (p = 0.017). HIIT leads to a BP reduction, which can still be detected up to 45 min after completion of the training. Even 60 min after exercise, pressures during a CPT showed a reduced augmentation, indicating an attenuated hemodynamic response to stress testing after HIIT.

Increased aortic wave reflection contributes to higher systolic blood pressure in adolescents born preterm.

PubMed

Kowalski, Remi R; Beare, Richard; Mynard, Jonathan P; Cheong, Jeanie L Y; Doyle, Lex W; Smolich, Joseph J; Cheung, Michael M H

2018-03-29

To evaluate the wave reflection characteristics in the aortic arch and common carotid artery of ex-preterm adolescents and assess their relationship to central blood pressure in a cohort followed prospectively since birth. Central blood pressures, pulse wave velocity, augmentation index, microvascular reactive hyperemia, arterial distensibility, compliance and stiffness index, and also aortic and carotid wave intensity were measured in 18-year-olds born extremely preterm at below 28 weeks' gestation (n = 76) and term-born controls (n = 42). Compared with controls, ex-preterm adolescents had higher central systolic (111 ± 11 vs. 105 ± 10 mmHg; P < 0.001) and diastolic blood pressures (73 ± 7 vs. 67 ± 7 mmHg; P < 0.001). Although conventional measures of arterial function and biomechanics such as pulse wave velocity and augmentation index were no different between groups, wave intensity analysis revealed elevated backward compression wave area (-0.39 ± 0.21 vs. -0.29 ± 0.17 W/m/s × 10; P = 0.03), backward compression wave pressure change (9.0 ± 3.5 vs. 6.6 ± 2.5 mmHg; P = 0.001) and reflection index (0.44 ± 0.15 vs. 0.32 ± 0.08; P < 0.001) in the aorta of ex-preterm adolescents compared with controls. These changes were less pronounced in the carotid artery. On multivariable analysis, forward and backward compression wave areas were the only biomechanical variables associated with central systolic pressure. Ex-preterm adolescents demonstrate elevated wave reflection indices in the aortic arch, which correlate with central systolic pressure. Wave intensity analysis may provide a sensitive novel marker of evolving vascular dysfunction in ex-preterm survivors.

[Central blood pressure and vascular damage].

PubMed

Pérez-Lahiguera, Francisco; Rodilla, Enrique; Costa, José Antonio; Pascual, José María

2015-07-20

The aim of this study was to assess the relationship between central blood pressure and vascular damage. This cross-sectional study involved 393 never treated hypertensive patients (166 women). Clinical blood pressure (BP), 24h blood pressure (BP24h) and central blood pressure (CBP) were measured. Vascular organ damage (VOD) was assessed by calculating the albumin/creatinine ratio (ACR), wave pulse pressure velocity and echocardiographic left ventricular mass index (LVMI). Patients with VOD had higher values of BP, BP24h, and CBP than patients without ACR. When comparing several systolic BP, systolic BP24h had a higher linear correlation with CBP (Z Steiger test: 2.26; P=.02) and LVMI (Z Steiger test: 3.23; P=.01) than PAC. In a multiple regression analysis corrected by age, sex and metabolic syndrome, all pressures were related with VOD but systolic BP24h showed the highest correlation. In a logistic regression analysis, having the highest tercile of systolic BP24h was the stronger predictor of VOD (multivariate odds ratio: 3.4; CI 95%: 2.5-5.5, P=.001). CBP does not have more correlation with VOD than other measurements of peripheral BP. Systolic BP24h is the BP measurement that best predicts VOD. Copyright © 2014 Elsevier España, S.L.U. All rights reserved.

Estimation of proliferative potentiality of central neurocytoma: correlational analysis of minimum ADC and maximum SUV with MIB-1 labeling index.

PubMed

Sakamoto, Ryo; Okada, Tomohisa; Kanagaki, Mitsunori; Yamamoto, Akira; Fushimi, Yasutaka; Kakigi, Takahide; Arakawa, Yoshiki; Takahashi, Jun C; Mikami, Yoshiki; Togashi, Kaori

2015-01-01

Central neurocytoma was initially believed to be benign tumor type, although atypical cases with more aggressive behavior have been reported. Preoperative estimation for proliferating activity of central neurocytoma is one of the most important considerations for determining tumor management. To investigate predictive values of image characteristics and quantitative measurements of minimum apparent diffusion coefficient (ADCmin) and maximum standardized uptake value (SUVmax) for proliferative activity of central neurocytoma measured by MIB-1 labeling index (LI). Twelve cases of central neurocytoma including one recurrence from January 2001 to December 2011 were included. Preoperative scans were conducted in 11, nine, and five patients for computed tomography (CT), diffusion-weighted imaging (DWI), and fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET), respectively, and ADCmin and SUVmax of the tumors were measured. Image characteristics were investigated using CT, T2-weighted (T2W) imaging and contrast-enhanced T1-weighted (T1W) imaging, and their differences were examined using the Fisher's exact test between cases with MIB-1 LI below and above 2%, which is recognized as typical and atypical central neurocytoma, respectively. Correlational analysis was conducted for ADCmin and SUVmax with MIB-1 LI. A P value <0.05 was considered significant. Morphological appearances had large variety, and there was no significant correlation with MIB-1 LI except a tendency that strong enhancement was observed in central neurocytomas with higher MIB-1 LI (P = 0.061). High linearity with MIB-1 LI was observed in ADCmin and SUVmax (r = -0.91 and 0.74, respectively), but only ADCmin was statistically significant (P = 0.0006). Central neurocytoma had a wide variety of image appearance, and assessment of proliferative potential was considered difficult only by morphological aspects. ADCmin was recognized as a potential marker for differentiation of atypical central neurocytomas from the typical ones. © The Foundation Acta Radiologica 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Aircraft engine with inter-turbine engine frame supported counter rotating low pressure turbine rotors

NASA Technical Reports Server (NTRS)

Seda, Jorge F. (Inventor); Dunbar, Lawrence W. (Inventor); Gliebe, Philip R. (Inventor); Szucs, Peter N. (Inventor); Brauer, John C. (Inventor); Johnson, James E. (Inventor); Moniz, Thomas (Inventor); Steinmetz, Gregory T. (Inventor)

2003-01-01

An aircraft gas turbine engine assembly includes an inter-turbine frame axially located between high and low pressure turbines. Low pressure turbine has counter rotating low pressure inner and outer rotors with low pressure inner and outer shafts which are at least in part rotatably disposed co-axially within a high pressure rotor. Inter-turbine frame includes radially spaced apart radially outer first and inner second structural rings disposed co-axially about a centerline and connected by a plurality of circumferentially spaced apart struts. Forward and aft sump members having forward and aft central bores are fixedly joined to axially spaced apart forward and aft portions of the inter-turbine frame. Low pressure inner and outer rotors are rotatably supported by a second turbine frame bearing mounted in aft central bore of aft sump member. A mount for connecting the engine to an aircraft is located on first structural ring.

Proteomic Characterization of Central Pacific Oxygen Minimum Zone Microbial Communities

NASA Astrophysics Data System (ADS)

Saunders, J. K.; McIlvin, M. M.; Moran, D.; Held, N.; Futrelle, J.; Webb, E.; Santoro, A.; Dupont, C.; Saito, M.

2018-05-01

Microbial proteomic profiles are excellent for surveying vast expanses of pelagic ecosystems for links between microbial communities and the biogeochemical cycles they mediate. Data from the ProteOMZ expedition supports the utility of this method.

Pressure induced change in the electronic state of Ta 4 Pd 3 Te 16

DOE PAGES

Jo, Na Hyun; Xiang, Li; Kaluarachchi, Udhara S.; ...

2017-04-24

Here, we present measurements of superconducting transition temperature, resistivity, magnetoresistivity, and temperature dependence of the upper critical field of Ta 4 Pd 3 Te 16 under pressures up to 16.4 kbar. All measured properties have an anomaly at ~ 2 $-$ 4 kbar pressure range; in particular there is a maximum in T c and upper critical field, H c2 ( 0 ), and minimum in low temperature, normal state resistivity. Qualitatively, the data can be explained considering the density of state at the Fermi level as a dominant parameter.

Simulation of the outdoor energy efficiency of an autonomous solar kit based on meteorological data for a site in Central Europa

NASA Astrophysics Data System (ADS)

Bouzaki, Mohammed Moustafa; Chadel, Meriem; Benyoucef, Boumediene; Petit, Pierre; Aillerie, Michel

2016-07-01

This contribution analyzes the energy provided by a solar kit dedicated to autonomous usage and installed in Central Europa (Longitude 6.10°; Latitude 49.21° and Altitude 160 m) by using the simulation software PVSYST. We focused the analysis on the effect of temperature and solar irradiation on the I-V characteristic of a commercial PV panel. We also consider in this study the influence of charging and discharging the battery on the generator efficiency. Meteorological data are integrated into the simulation software. As expected, the solar kit provides an energy varying all along the year with a minimum in December. In the proposed approach, we consider this minimum as the lowest acceptable energy level to satisfy the use. Thus for the other months, a lost in the available renewable energy exists if no storage system is associated.

When an Increase in Central Systolic Pressure Overrides the Benefits of Heart Rate Lowering.

PubMed

Messerli, Franz H; Rimoldi, Stefano F; Bangalore, Sripal; Bavishi, Chirag; Laurent, Stephane

2016-08-16

An elevated resting heart rate has been unequivocally linked to adverse cardiovascular events. Conversely, a physiologically low heart rate may confer longevity benefits. Moreover, pharmacological heart rate lowering reduces cardiovascular outcomes in patients with heart failure, with the magnitude of the reduction associated with survival benefit. In contrast, pharmacological heart rate lowering paradoxically increases cardiovascular events in hypertension, possibly because it elicits a ventricular-vascular mismatch, leading to increased central systolic blood pressure (BP). By the same hemodynamic mechanism, pharmacological heart rate lowering also engenders an increase in central (aortic) BP in coronary heart disease and, as a consequence, fails to decrease myocardial oxygen consumption. Whether in heart failure, hypertension, or coronary heart disease, or even athletes, heart rate lowering consistently increases central systolic pressure. The increase in central systolic BP is prone to abolish the potential benefits of heart rate lowering interventions, possibly accounting for failure to reduce outcomes in patients with hypertension and coronary artery disease. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Left ventricular pressure and volume data acquisition and analysis using LabVIEW.

PubMed

Cassidy, S C; Teitel, D F

1997-03-01

To automate analysis of left ventricular pressure-volume data, we used LabVIEW to create applications that digitize and display data recorded from conductance and manometric catheters. Applications separate data into cardiac cycles, calculate parallel conductance, and calculate indices of left ventricular function, including end-systolic elastance, preload-recruitable stroke work, stroke volume, ejection fraction, stroke work, maximum and minimum derivative of ventricular pressure, heart rate, indices of relaxation, peak filling rate, and ventricular chamber stiffness. Pressure-volume loops can be graphically displayed. These analyses are exported to a text-file. These applications have simplified and automated the process of evaluating ventricular function.

Design Factors for Applying Cryogen Storage and Delivery Technology to Solar Thermal Propulsion

NASA Technical Reports Server (NTRS)

Millis, Marc G.

1996-01-01

Thermodynamic Vent System (TVS) and Multilayer Insulation (MLI) technology, originally developed for long term storage of cryogen propellants in microgravity, is ideally suited for propellant storage and delivery systems for solar thermal propulsion. With this technology the heat-induced pressure rise in the tank provides the propellant delivery pressure without the need for an auxiliary pressurant system, and propellant delivery is used to remove the excess heat to control tank pressure. The factors to consider in designing such a balanced system, are presented. An example of a minimum system design is presented along with examples of laboratory-tested hardware.

Comparison of laboratory and ambulatory measures of central blood pressure and pulse wave reflection: hitting the target or missing the mark?

PubMed

Burns, Matthew J; Seed, Jeremy D; Incognito, Anthony V; Doherty, Connor J; Notay, Karambir; Millar, Philip J

2018-04-01

Prior studies demonstrating clinical significance of noninvasive estimates of central blood pressure (BP) and pulse wave reflection have relied primarily on discrete resting measures. The aim of this study was to compare central BP and pulse wave reflection measures sampled during a single resting laboratory visit against those obtained under ambulatory conditions. The secondary aim was to investigate the reproducibility of ambulatory central BP and pulse wave reflection measurements. Forty healthy participants (21 males; 24 ± 3 years) completed three measurements of brachial artery pulse wave analysis (Oscar 2 with SphygmoCor Inside) in the laboratory followed by 24 hours of ambulatory monitoring. Seventeen participants repeated the 24-hour ambulatory monitoring visit after at least 1 week. Ambulatory measures were divided into daytime (9 AM-9 PM), nighttime (1 AM-6 AM), and 24-hour periods. Compared with laboratory measurements, central systolic BP, augmentation pressure, and augmentation index (with and without heart rate normalization) were higher (all P < .01) during daytime and 24-hour periods but lower during the nighttime period (all P < .001). The drop in nighttime brachial systolic BP was larger than central systolic pressure (Δ -20 ± 6 vs. -15 ± 6 mm Hg; P < .0001). Repeat ambulatory measurements of central BP and pulse wave reflection displayed good-to-excellent intraclass correlation coefficients (r = 0.58-0.86; all P < .01), although measures of pulse wave reflection had higher coefficients of variation (14%-41%). The results highlight absolute differences in central BP and pulse wave reflection between discrete laboratory and ambulatory conditions. The use of ambulatory measures of central BP and pulse wave reflection warrant further investigation for clinical prognostic value. Copyright © 2018 American Heart Association. Published by Elsevier Inc. All rights reserved.

Effects of nifedipine and captopril on vascular capacitance of ganglion-blocked anesthetized dogs.

PubMed

Ogilvie, R I; Zborowska-Sluis, D

1990-03-01

The hemodynamic effects of nifedipine and captopril at doses producing similar reductions in arterial pressure were studied in pentobarbital-anesthetized ventilated dogs after splenectomy during ganglion blockade with hexamethonium. Mean circulatory filling pressure (Pmcf) was determined during transient circulatory arrest induced by acetylcholine at baseline circulating blood volumes and after increases of 5 and 10 mL/kg. Central blood volumes (pulmonary artery to aortic root) were determined from transit times, and separately determined cardiac outputs (right atrium to pulmonary artery) were estimated by thermodilution. Nifedipine (n = 5) increased Pmcf at all circulating blood volumes and reduced total vascular capacitance without a change in total vascular compliance. Central blood volume, right atrial pressure, and cardiac output were increased with induced increases in circulating blood volume. In contrast, captopril (n = 5) did not alter total vascular capacitance, central blood volume, right atrial pressure, or cardiac output at baseline or with increased circulating volume. Thus, at doses producing similar reductions in arterial pressure, nifedipine but not captopril increased venous return and cardiac output in ganglion-blocked dogs.

[Minimum Standards for the Spatial Accessibility of Primary Care: A Systematic Review].

PubMed

Voigtländer, S; Deiters, T

2015-12-01

Regional disparities of access to primary care are substantial in Germany, especially in terms of spatial accessibility. However, there is no legally or generally binding minimum standard for the spatial accessibility effort that is still acceptable. Our objective is to analyse existing minimum standards, the methods used as well as their empirical basis. A systematic literature review was undertaken of publications regarding minimum standards for the spatial accessibility of primary care based on a title word and keyword search using PubMed, SSCI/Web of Science, EMBASE and Cochrane Library. 8 minimum standards from the USA, Germany and Austria could be identified. All of them specify the acceptable spatial accessibility effort in terms of travel time; almost half include also distance(s). The travel time maximum, which is acceptable, is 30 min and it tends to be lower in urban areas. Primary care is, according to the identified minimum standards, part of the local area (Nahbereich) of so-called central places (Zentrale Orte) providing basic goods and services. The consideration of means of transport, e. g. public transport, is heterogeneous. The standards are based on empirical studies, consultation with service providers, practical experiences, and regional planning/central place theory as well as on legal or political regulations. The identified minimum standards provide important insights into the effort that is still acceptable regarding spatial accessibility, i. e. travel time, distance and means of transport. It seems reasonable to complement the current planning system for outpatient care, which is based on provider-to-population ratios, by a gravity-model method to identify places as well as populations with insufficient spatial accessibility. Due to a lack of a common minimum standard we propose - subject to further discussion - to begin with a threshold based on the spatial accessibility limit of the local area, i. e. 30 min to the next primary care provider for at least 90% of the regional population. The exceeding of the threshold would necessitate a discussion of a health care deficit and in line with this a potential need for intervention, e. g. in terms of alternative forms of health care provision. © Georg Thieme Verlag KG Stuttgart · New York.

Venous return curves obtained from graded series of valsalva maneuvers

NASA Technical Reports Server (NTRS)

Mastenbrook, S. M., Jr.

1974-01-01

The effects were studied of a graded series of valsalva-like maneuvers on the venous return, which was measured transcutaneously in the jugular vein of an anesthetized dog, with the animal serving as its own control. At each of five different levels of central venous pressure, the airway pressure which just stopped venous return during each series of maneuvers was determined. It was found that this end-point airway pressure is not a good estimator of the animal's resting central venous pressure prior to the simulated valsalva maneuver. It was further found that the measured change in right atrial pressure during a valsalva maneuver is less than the change in airway pressure during the same maneuver, instead of being equal, as had been expected. Relative venous return curves were constructed from the data obtained during the graded series of valsalva maneuvers.

Testosterone Conversion Blockade Increases Breathing Stability in Healthy Men during NREM Sleep

PubMed Central

Chowdhuri, Susmita; Bascom, Amy; Mohan, David; Diamond, Michael P.; Badr, M. Safwan

2013-01-01

Study Objectives: Gender differences in the prevalence of sleep apnea/hypopnea syndrome may be mediated via male sex hormones. Our objective was to determine the exact pathway for a testosterone-mediated increased propensity for central sleep apnea via blockade of the 5α-reductase pathway of testosterone conversion by finasteride. Design: Randomization to oral finasteride vs. sham, single-center study. Setting: Sleep research laboratory. Participants: Fourteen healthy young males without sleep apnea Intervention: Hypocapnia was induced via brief nasal noninvasive positive pressure ventilation during stable NREM sleep. Cessation of mechanical ventilation resulted in hypocapnic central apnea or hypopnea. Measurements and Results: The apnea threshold (AT) was defined as the end-tidal CO2 (PETCO2) that demarcated the central apnea closest to the eupneic PETCO2. The CO2 reserve was defined as the difference in PETCO2 between eupnea and AT. The apneic threshold and CO2 reserve were measured at baseline and repeated after at a minimum of 1 month. Administration of finasteride resulted in decreased serum dihydrotestosterone. In the finasteride group, the eupneic ventilatory parameters were unchanged; however, the AT was decreased (38.9 ± 0.6 mm Hg vs.37.7 ± 0.9 mm Hg, P = 0.02) and the CO2 reserve was increased (-2.5 ± 0.3 mm Hg vs. -3.8 ± 0.5 mm Hg, P = 0.003) at follow-up, with a significantly lower hypocapnic ventilatory response, thus indicating increased breathing stability during sleep. No significant changes were noted in the sham group on follow-up study. Conclusions: Inhibition of testosterone action via the 5α-reductase pathway may be effective in alleviating breathing instability during sleep, presenting an opportunity for novel therapy for central sleep apnea in selected populations. Citation: Chowdhuri S; Bascom A; Mohan D; Diamond MP; Badr MS. Testosterone conversion blockade increases breathing stability in healthy men during NREM sleep. SLEEP 2013;36(12):1793-1798. PMID:24293753

Central arterial characteristics of gout patients with chronic kidney diseases.

PubMed

Celik, Gulperi; Yilmaz, Sema; Kebapcilar, Levent; Gundogdu, Ali

2017-05-01

The aim of this study was to investigate the relationship between central blood pressure, arterial stiffness parameters and renal function parameters in gout patients with chronic kidney disease (CKD) and without CKD. The study enrolled 48 gout patients and 32 control subjects. Central blood pressure, arterial stiffness parameters and renal function parameters in gout patients were investigated. The vascular measurements were performed with an arteriograph. Of the gout patients, 40.1% had CKD. The 24-h pulse pressure (PP) (P < 0.001), central systolic blood pressure (SBP) (P < 0.001), central diastolic blood pressure (DBP) (P < 0.001), cardiac output (CO) (P < 0.001) and peripheral resistance (P = 0.004) were significantly higher in the all patients with gout compared to healthy control subjects. Moreover, when the gout patients with and without CKD were compared, the gout patients with CKD had higher 24-h PP (P = 0.009), 24-h augmentation index standardized to a heart rate of 75 beats per min (AIx@75) (P < 0.023), daytime PP (P = 0.001), daytime AIx@75 (P = 0.027), and nighttime PP (P = 0.035) than the gout patients without CKD. In our study, gout patients with CKD had worse and more emphasized evidence of arterial stiffness than gout patients without CKD. Further investigations with large sample sizes are needed to evaluate the effect of CKD on the arterial stiffness of gout patients. © 2015 Asia Pacific League of Associations for Rheumatology and Wiley Publishing Asia Pty Ltd.

49 CFR 192.555 - Uprating to a pressure that will produce a hoop stress of 30 percent or more of SMYS in steel...

Code of Federal Regulations, 2010 CFR

2010-10-01

... stress of 30 percent or more of SMYS in steel pipelines. 192.555 Section 192.555 Transportation Other...: MINIMUM FEDERAL SAFETY STANDARDS Uprating § 192.555 Uprating to a pressure that will produce a hoop stress... produce a hoop stress of 30 percent or more of SMYS and that is above the established maximum allowable...

Feasibility Study of Cyclic Pressure Testing Thick-Walled Cylinders

DTIC Science & Technology

1975-01-01

Watervliet, and also • for tests on Navy barrela, is the hydrostatic pressure cycling test. This test employs a cloae-fitting, high -strength steel...mandrel to keep water volume at a minimum. High preaaure pumps then cycle the water up to the desired teat pres- • sure, thirty to fifty thousand...be accomplished using s high energy metalworking process - electrohydraulice. m • Electrohydraulica is a metalworking process which employs the

49 CFR 192.555 - Uprating to a pressure that will produce a hoop stress of 30 percent or more of SMYS in steel...

Code of Federal Regulations, 2011 CFR

2011-10-01

... stress of 30 percent or more of SMYS in steel pipelines. 192.555 Section 192.555 Transportation Other...: MINIMUM FEDERAL SAFETY STANDARDS Uprating § 192.555 Uprating to a pressure that will produce a hoop stress... produce a hoop stress of 30 percent or more of SMYS and that is above the established maximum allowable...

Ballistic protons in incoherent exclusive vector meson production as a measure of rare parton fluctuations at an electron-ion collider

DOE PAGES

Lappi, T.; Venugopalan, R.; Mantysaari, H.

2015-02-25

We argue that the proton multiplicities measured in Roman pot detectors at an electron ion collider can be used to determine centrality classes in incoherent diffractive scattering. Incoherent diffraction probes the fluctuations in the interaction strengths of multi-parton Fock states in the nuclear wavefunctions. In particular, the saturation scale that characterizes this multi-parton dynamics is significantly larger in central events relative to minimum bias events. As an application, we examine the centrality dependence of incoherent diffractive vector meson production. We identify an observable which is simultaneously very sensitive to centrality triggered parton fluctuations and insensitive to details of the model.

Application of Semiparametric Spline Regression Model in Analyzing Factors that In uence Population Density in Central Java

NASA Astrophysics Data System (ADS)

Sumantari, Y. D.; Slamet, I.; Sugiyanto

2017-06-01

Semiparametric regression is a statistical analysis method that consists of parametric and nonparametric regression. There are various approach techniques in nonparametric regression. One of the approach techniques is spline. Central Java is one of the most densely populated province in Indonesia. Population density in this province can be modeled by semiparametric regression because it consists of parametric and nonparametric component. Therefore, the purpose of this paper is to determine the factors that in uence population density in Central Java using the semiparametric spline regression model. The result shows that the factors which in uence population density in Central Java is Family Planning (FP) active participants and district minimum wage.

Thermodynamic properties by Equation of state of liquid sodium under pressure

NASA Astrophysics Data System (ADS)

Li, Huaming; Sun, Yongli; Zhang, Xiaoxiao; Li, Mo

Isothermal bulk modulus, molar volume and speed of sound of molten sodium are calculated through an equation of state of a power law form within good precision as compared with the experimental data. The calculated internal energy data show the minimum along the isothermal lines as the previous result but with slightly larger values. The calculated values of isobaric heat capacity show the unexpected minimum in the isothermal compression. The temperature and pressure derivative of various thermodynamic quantities in liquid Sodium are derived. It is discussed about the contribution from entropy to the temperature and pressure derivative of isothermal bulk modulus. The expressions for acoustical parameter and nonlinearity parameter are obtained based on thermodynamic relations from the equation of state. Both parameters for liquid Sodium are calculated under high pressure along the isothermal lines by using the available thermodynamic data and numeric derivations. By comparison with the results from experimental measurements and quasi-thermodynamic theory, the calculated values are found to be very close at melting point at ambient condition. Furthermore, several other thermodynamic quantities are also presented. Scientific Research Starting Foundation from Taiyuan university of Technology, Shanxi Provincial government (``100-talents program''), China Scholarship Council and National Natural Science Foundation of China (NSFC) under Grant No. 11204200.

Charts and Tables for Estimating the Stability of the Compressible Laminar Boundary Layer with Heat Transfer and Arbitrary Pressure Gradient

NASA Technical Reports Server (NTRS)

Tetervin, Neal

1959-01-01

The minimum critical Reynolds numbers for the similar solutions of the compressible laminar boundary layer computed by Cohen and Reshotko and also for the Falkner and Skan solutions as recomputed by Smith have been calculated by Lin's rapid approximate method for two-dimensional disturbances. These results enable the stability of the compressible laminar boundary layer with heat transfer and pressure gradient to be easily estimated after the behavior of the boundary layer has been computed by the approximate method of Cohen and Reshotko. The previously reported unusual result (NACA Technical Note 4037) that a highly cooled stagnation point flow is more unstable than a highly cooled flat-plate flow is again encountered. Moreover, this result is found to be part of the more general result that a favorable pressure gradient is destabilizing for very cool walls when the Mach number is less than that for complete stability. The minimum critical Reynolds numbers for these wall temperature ratios are, however, all larger than any value of the laminar-boundary-layer Reynolds number likely to be encountered. For Mach numbers greater than those for which complete stability occurs a favorable pressure gradient is stabilizing, even for very cool walls.

Investigation of positive shaft seals

NASA Technical Reports Server (NTRS)

Pfouts, J. O.

1970-01-01

Welded metal bellows secondary seals prevent secondary seal leakage with a minimum number of potential leak paths. High performance seal is obtained by controlling the potentially unstable seal-face movements induced by mechanical vibrations and fluid pressure pulsations.

Effects of Positive Airway Pressure on Patients with Obstructive Sleep Apnea during Acute Ascent to Altitude

PubMed Central

Nishida, Katsufumi; Cloward, Tom V.; Weaver, Lindell K.; Brown, Samuel M.; Bell, James E.; Grissom, Colin K.

2015-01-01

Rationale: In acute ascent to altitude, untreated obstructive sleep apnea (OSA) is often replaced with central sleep apnea (CSA). In patients with obstructive sleep apnea who travel to altitude, it is unknown whether their home positive airway pressure (PAP) settings are sufficient to treat their obstructive sleep apnea, or altitude-associated central sleep apnea. Methods: Ten participants with positive airway pressure–treated obstructive sleep apnea, who reside at 1,320 m altitude, underwent polysomnography on their home positive airway pressure settings at 1,320 m and at a simulated altitude of 2,750 m in a hypobaric chamber. Six of the participants were subsequently studied without positive airway pressure at 2,750 m. Measurements and Main Results: At 1,320 m, all participants’ sleep apnea was controlled with positive airway pressure on home settings; at 2,750, no participants’ sleep apnea was controlled. At higher altitude, the apnea–hypopnea index was higher (11 vs. 2 events/h; P < 0.01), mostly due to hypopneas (10.5 vs. 2 events/h; P < 0.01). Mean oxygen saturations were lower (88 vs. 93%; P < 0.01) and total sleep time was diminished (349 vs. 393 min; P = 0.03). Four of six participants without positive airway pressure at 2,750 m required supplemental oxygen to prevent sustained oxygen saturation (as determined by pulse oximetry) less than 80%. Positive airway pressure also was associated with reduced central sleep apnea (0 vs. 1; P = 0.03), improved sleep time (358 vs. 292 min; P = 0.06), and improved sleep efficiency (78 vs. 63%; P = 0.04). Conclusions: Acute altitude exposure in patients with obstructive sleep apnea treated with positive airway pressure is associated with hypoxemia, decreased sleep time, and increased frequency of hypopneas compared with baseline altitude. Application of positive airway pressure at altitude is associated with decreased central sleep apnea and increased sleep efficiency. PMID:25884271

The human, primate and rabbit ultraviolet action spectra

NASA Technical Reports Server (NTRS)

Pitts, D. G.; Gibbons, W. D.

1972-01-01

A 5000 watt xenon-mercury high pressure lamp was used to produce a continuous ultraviolet spectrum. Human and animal exposures were made to establish the photokeratitis threshold and abiotic action spectrum. The lower limit of the abiotic action spectrum was 220 nm while the upper limit was 310 nm. The radiant exposure threshold at 270 nm was 0.005 watts/sq cm for the rabbit, 0.004 watts/sq cm for the primate, and 0.004 watts/ sq cm for the human. The rabbit curve was bi-peaked with minimums at 220 nm, 240 nm and 270 nm. The primate curve was tri-peaked with minimums at 220 nm, 240 nm and 270 nm. The human data showed a rather shallow curve with a minimum at 270 nm. Formulas and calculations are given to predict minimum exposure times for ocular damage to man in outer space, to establish valid safety criteria, and to establish protective design criteria.

Extreme pointer years in tree-ring records of Central Spain as evidence of climatic events and the eruption of the Huaynaputina Volcano (Peru, 1600 AD)

NASA Astrophysics Data System (ADS)

Génova, M.

2012-04-01

The study of pointer years of numerous tree-ring chronologies of the central Iberian Peninsula (Sierra de Guadarrama) could provide complementary information about climate variability over the last 405 yr. In total, 64 pointer years have been identified: 30 negative (representing minimum growths) and 34 positive (representing maximum growths), the most significant of these being 1601, 1963 and 1996 for the negative ones, and 1734 and 1737 for the positive ones. Given that summer precipitation was found to be the most limiting factor for the growth of Pinus in the Sierra de Guadarrama in the second half of the 20th century, it is also an explanatory factor in almost 50% of the extreme growths. Furthermore, these pointer years and intervals are not evenly distributed throughout time. Both in the first half of the 17th and in the second half of 20th, they were more frequent and more extreme and these periods are the most notable for the frequency of negative pointer years in Central Spain. The interval 1600-1602 is of special significance, being one of the most unfavourable for tree growth in the centre of Spain, with 1601 representing the minimum index in the regional chronology. We infer that this special minimum annual increase was the effect of the eruption of Huaynaputina, which occurred in Peru at the beginning of 1600 AD. This is the first time that the effects of this eruption in the tree-ring records of Southern Europe have been demonstrated.

K(892)* resonance production in Au+Au and p+p collisions at {radical}s{sub NN} = 200 GeV at RHIC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adams, J.; Aggarwal, M.M.; Ahammed, Z.

2004-12-09

The short-lived K(892)* resonance provides an efficient tool to probe properties of the hot and dense medium produced in relativistic heavy-ion collisions. We report measurements of K* in {radical}s{sub NN} = 200 GeV Au+Au and p+p collisions reconstructed via its hadronic decay channels K(892)*{sup 0} {yields} K{pi} and K(892)*{sup +-} {yields} K{sub S}{sup 0}{pi}{sup +-} using the STAR detector at RHIC. The K*{sup 0} mass has been studied as function of p{sub T} in minimum bias p + p and central Au+Au collisions. The K* p{sub T} spectra for minimum bias p + p interactions and for Au+Au collisions inmore » different centralities are presented. The K*/K ratios for all centralities in Au+Au collisions are found to be significantly lower than the ratio in minimum bias p + p collisions, indicating the importance of hadronic interactions between chemical and kinetic freeze-outs. The nuclear modification factor of K* at intermediate p{sub T} is similar to that of K{sub S}{sup 0}, but different from {Lambda}. This establishes a baryon-meson effect over a mass effect in the particle production at intermediate p{sub T} (2 < p{sub T} {le} 4 GeV/c). A significant non-zero K*{sup 0} elliptic flow (v{sub 2}) is observed in Au+Au collisions and compared to the K{sub S}{sup 0} and {Lambda} v{sub 2}.« less

Geo-mechanical modeling and selection of suitable layer for hydraulic fracturing operation in an oil reservoir (south west of Iran)

NASA Astrophysics Data System (ADS)

Darvish, Hoda; Nouri-Taleghani, Morteza; Shokrollahi, Amin; Tatar, Afshin

2015-11-01

According to the growth of demands to oil resources, increasing the rate of oil production seems necessary. However, oil production declines with time as a result of pressure drop in reservoir as well as sealing of microscopic cracks and pores in the reservoir rock. Hydraulic fracturing is one of the common methods with high performance, which is widely applied to oil and gas reservoirs. In this study, wells in three sections of east, center, and west sides of a field are compared regarding the suitable layer for hydraulic fracturing operation. Firstly, elastic modulus were obtained in both dynamic and static conditions, then uniaxial compressive strength (UCS), type of shear and tensile failures, the most accurate model of failure in wells, safe and stable mud window, the best zone and layers, and finally reference pressures are determined as nominates for hydraulic fracturing. Types of shear failure in minimum, and maximum range of model and in tensile model were determined to be "Shear failure wide breakout (SWBO)", "Shear narrow breakout (SNBO)", and "Tensile vertical failure (TVER)", respectively. The range of safe mud window (SMW) in the studied wells was almost in the same range as it was in every three spots of the field. This range was determined between 5200-8800psi and 5800-10100psi for Ilam and Sarvak zones, respectively. Initial fracture pressure ranges for selected layers were determined 11,759-14,722, 11,910-14,164, and 11,848-14,953psi for the eastern, central, and western wells. Thus, western wells have the best situation for Hydraulic fracturing operation. Finally, it was concluded that the operation is more economic in Sarvak zone and western wells.

Intraocular pressure and cerebral oxygenation during prolonged headward acceleration.

PubMed

Eiken, Ola; Keramidas, Michail E; Taylor, Nigel A S; Grönkvist, Mikael

2017-01-01

Supra-tolerance head-to-foot directed gravitoinertial load (+Gz) typically induces a sequence of symptoms/signs, including loss of: peripheral vision-central vision-consciousness. The risk of unconsciousness is greater when anti-G-garment failure occurs after prolonged rather than brief exposures, presumably because, in the former condition, mental signs are not consistently preceded by impaired vision. The aims were to investigate if prolonged exposure to moderately elevated +Gz reduces intraocular pressure (IOP; i.e., improves provisions for retinal perfusion), or the cerebral anoxia reserve. Subjects were exposed to 4-min +Gz plateaux either at 2 and 3 G (n = 10), or at 4 and 5 G (n = 12). Measurements included eye-level mean arterial pressure (MAP), oxygenation of the cerebral frontal cortex, and at 2 and 3 G, IOP. IOP was similar at 1 (14.1 ± 1.6 mmHg), 2 (14.0 ± 1.6 mmHg), and 3 G (14.0 ± 1.6 mmHg). During the G exposures, MAP exhibited an initial prompt drop followed by a partial recovery, end-exposure values being reduced by ≤30 mmHg. Cerebral oxygenation showed a similar initial drop, but without recovery, and was followed by either a plateau or a further slight decrement to a minimum of about -14 μM. Gz loading did not affect IOP. That cerebral oxygenation remained suppressed throughout these G exposures, despite a concomitant partial recovery of MAP, suggests that the increased risk of unconsciousness upon G-garment failure after prolonged +Gz exposure is due to reduced cerebral anoxia reserve.

The timing of metamorphism in the Odenwald-Spessart basement, Mid-German Crystalline Zone

NASA Astrophysics Data System (ADS)

Will, T. M.; Schulz, B.; Schmädicke, E.

2017-07-01

New in situ electron microprobe monazite and white mica 40Ar/39Ar step heating ages support the proposition that the Odenwald-Spessart basement, Mid-German Crystalline Zone, consists of at least two distinct crustal terranes that experienced different geological histories prior to their juxtaposition. The monazite ages constrain tectonothermal events at 430 ± 43 Ma, 349 ± 14 Ma, 331 ± 16 Ma and 317 ± 12 Ma/316 ± 4 Ma, and the 40Ar/39Ar analyses provide white mica ages of 322 ± 3 Ma and 324 ± 3 Ma. Granulite-facies metamorphism occurred in the western Odenwald at c. 430 and 349 Ma, and amphibolite-facies metamorphism affected the eastern Odenwald and the central Spessart basements between c. 324 and 316 Ma. We interpret these data to indicate that the Otzberg-Michelbach Fault Zone, which separates the eastern Odenwald-Spessart basement from the Western Odenwald basement, is part of the Rheic Suture, which marks the position of a major Variscan plate boundary separating Gondwana- and Avalonia-derived crustal terranes. The age of the Carboniferous granulite-facies event in the western Odenwald overlaps with the minimum age of eclogite-facies metamorphism in the adjacent eastern Odenwald. The granulite- and eclogite-facies rocks experienced contrasting pressure-temperature paths but occur in close spatial proximity, being separated by the Rheic Suture. As high-pressure and high-temperature metamorphisms are of similar age, we interpret the Odenwald-Spessart basement as a paired metamorphic belt and propose that the adjacent high-pressure and high-temperature rocks were metamorphosed in the same subduction zone system. Juxtaposition of these rocks occurred during the final stages of the Variscan orogeny along the Rheic Suture.

Electrocardiographic left ventricular hypertrophy criteria and ambulatory blood pressure monitoring parameters in adults.

PubMed

Gómez-Marcos, Manuel A; Recio-Rodríguez, Jose I; Patino-Alonso, María C; Agudo-Conde, Cristina; Fernandez-Alonso, Carmen; Martinez Vizcaino, Vicente; Cantera, Carlos Martin; Guenaga-Saenz, Nahia; González-Viejo, Natividad; García-Ortiz, Luis

2014-03-01

To examine the relationship between ambulatory blood pressure monitoring parameters (ABPM) and electrocardiographic criteria for left-ventricular hypertrophy (LVH) in adults. This study analyzed 1,544 subjects from the EVIDENT study (mean age = 55 ± 14 years; 61% women). A standard electrocardiograph (ECG) and 10 criteria were used to detect LVH. Office and ABPM were performed, and we analyzed 24-hour systolic blood pressure (SBP) and diastolic blood pressure (DBP), percentage of time awake with SBP ≥135 mm Hg, percentage of time asleep with SBP ≥120 mm Hg, and central aortic blood pressure. LVH according to some electrocardiographic criteria was found in 11.30% of the patients (16.60% of men and 7.70% of women). The patients with LVH were older; had higher values for office, 24-hour and, central aortic blood pressure; were more likely to be men; and had a higher prevalence of obesity, diabetes, and antihypertensive or lipid-lowering drug use. In the logistic regression analysis, the association between the parameters of ABPM and LVH, after adjusting for age, sex, body mass index, and heart rate, remained statistically significant. Twenty-four hour blood pressure, the percentage of time with elevated awake and asleep SBPs, and the central systolic blood pressure are related to the presence of LVH as determined by ECG in adults. These results indicate the potential importance of the monitoring and control of different 24-hour parameters of blood pressure in addition to the standard clinic blood pressure with respect to the development of LVH. ClinicalTrials.gov identifier NCT01325064.

National health insurance reconsidered: dilemmas and opportunities.

PubMed

Battistella, R M; Weil, T P

1989-01-01

Changing social and economic constraints are precipitating a reformulation of the role of government in the provision of social welfare services. The authors conclude that government intervention in the health sector is bound to expand rather than contract because centralization is the key to reconciling otherwise divergent political demands for spending controls and greater equality of access to quality care for the increasing number of uninsured or underinsured persons. In the past eight years, the federal government has unleashed competitive market principles that have had negative side effects on the nation's health services. Payers, providers, and consumers will likely seek to protect themselves by forming coalitions, as happened recently in Massachusetts where the law now requires employers to provide minimum health insurance benefits to their employees. Escalating pressures to correct the damages from short-term piecemeal solutions to problems of health finance and delivery will provide the chief dynamic for universal health insurance in the United States. New economic, social, and political realities suggest, however, an eclectic strategy for attaining this goal that bears little resemblance to the conventional wisdom that guided health policy throughout the postwar period.

ER-2 Doppler Radar (EDOP) Investigations of the Eyewall of Hurricane Bonnie CAMEX-3

NASA Technical Reports Server (NTRS)

Heymsfield, G. M.; Halverson, J.; Simpson, J.; Tian, L.; Bui, P.; Einaudi, Franco (Technical Monitor)

2000-01-01

A persistent, mesoscale region of intense eyewall convection contained within Hurricane Bonnie on 23 August 1998 is examined from multiple observations synthesized from the NASA ER-2 and DC-8 aircraft. The intense convection occurred late in the day as Bonnie was attaining its minimum central pressure and during a stage when the inner core featured a markedly asymmetric structure. The main purpose of this paper is to describe the internal structure of a convective burst and its relationship to the warm core using a synthesis of high-resolution satellite, aircraft radar, and in situ data. An exceptionally vigorous eyewall tower penetrating to nearly 18 km is described. A second intense eyewall tower, adjacent to the eye, is shown to be associated with a mesoscale subsiding current of air that extends horizontally nearly 20 km into the eye interior. The subsidence occupies a substantial depth within the eye and appears to be a much larger scale feature than the convectively-induced, symmetric overturning which commonly occurs on the upper-level flanks of convective towers in other tropical environments.

Clinical Outcomes of Intravitreal Preservative-Free Triamcinolone Preparation (Triesence®) for Cystoid Macular Oedema and Inflammation in Patients with Uveitis.

PubMed

Steeples, Laura R; Anand, Nitin; Moraji, Jiten; Jones, Nicholas P

2017-03-20

To assess the outcomes of intravitreal benzyl alcohol-free triamcinolone acetonide suspension in uveitis-related macular oedema. Single-center retrospective cohort study of 66 injections to 44 eyes of 40 patients. Uveitis diagnosis, systemic and local therapy, intraocular pressure (IOP), central retinal thickness (CRT), number of injections, time to re-injection and side-effects were noted during 6-months minimum follow-up. Sixty eight percent of eyes received a single injection. 18% required 2 injections, and 13% received ≥3 injections with mean time to second and third injections of 25.5 and 52.7 weeks, respectively. 90% of injections were unilateral. Mean CRT reduced, and by 12-weeks visual acuity improvement >0.3logMar was achieved in 46%. Cataract progression (47%) and IOP>21 mmHg (45%) were the commonest adverse events. Preservative-free triamcinolone is an additional option for uveitis-related macular oedema, particularly in unilateral cases, with favorable CRT and visual outcomes. Repeat injections may be necessary, and the period of efficacy varies between eyes.

Associations between glycaemic deterioration and aortic stiffness and central blood pressure: the ADDITION-PRO Study.

PubMed

Johansen, Nanna B; Rasmussen, Signe S; Wiinberg, Niels; Vistisen, Dorte; Jørgensen, Marit E; Pedersen, Erling B; Lauritzen, Torsten; Sandbæk, Annelli; Witte, Daniel R

2017-09-01

In the context of screening for diabetes, we examined levels of central haemodynamics among individuals with different levels of diabetes risk and analysed the impact of glycated haemoglobin A (HbA1c) and HbA1c changes on central haemodynamics. A Danish population-based stepwise screening programme for diabetes including a diabetes risk score (DRS) questionnaire and glucose measurements identified seven groups of individuals at increasing levels of diabetes risk. After 7.8 years of follow-up, 2048 individuals underwent aortic stiffness assessment by carotid-femoral pulse wave velocity (aPWV) and assessment of central blood pressure (BP). We compared differences in central haemodynamics at follow-up between the diabetes risk groups and analysed the impact of HbA1c at screening and HbA1c change on central haemodynamics at follow-up adjusting for relevant confounders. At screening, median age was 59.0 years, and median HbA1c was 5.7%. At follow-up, median aPWV was 8.0 m/s, and median central SBP was 123.5 mmHg. Among individuals with high DRS, aPWV, central SBP and DBP, and pulse pressure were higher in individuals with impaired glucose tolerance than normal glucose tolerance. Per 1%-point higher HbA1c at screening, aPWV was 0.23 m/s (95% confidence interval: 0.00; 0.46) higher, and central DBP was 1.35 mmHg (95% confidence interval: 0.19; 2.51) lower, whereas HbA1c change was not associated with any of the central haemodynamics. Dysglycaemia is associated with future aortic stiffness. However, glycaemic deterioration over 7.8 years does not affect aortic stiffness or central BP independently of other cardiometabolic risk factors.

The Effect of Size and Species on Lens Intracellular Hydrostatic Pressure

PubMed Central

Gao, Junyuan; Sun, Xiurong; Moore, Leon C.; Brink, Peter R.; White, Thomas W.; Mathias, Richard T.

2013-01-01

Purpose. Previous experiments showed that mouse lenses have an intracellular hydrostatic pressure that varied from 335 mm Hg in central fibers to 0 mm Hg in surface cells. Model calculations predicted that in larger lenses, all else equal, pressure should increase as the lens radius squared. To test this prediction, lenses of different radii from different species were studied. Methods. All studies were done in intact lenses. Intracellular hydrostatic pressures were measured with a microelectrode-manometer–based system. Membrane conductances were measured by frequency domain impedance analysis. Intracellular Na+ concentrations were measured by injecting the Na+-sensitive dye sodium-binding benzofuran isophthalate. Results. Intracellular hydrostatic pressures were measured in lenses from mice, rats, rabbits, and dogs with radii (cm) 0.11, 0.22, 0.49, and 0.57, respectively. In each species, pressure varied from 335 ± 6 mm Hg in central fiber cells to 0 mm Hg in surface cells. Further characterization of transport in lenses from mice and rats showed that the density of fiber cell gap junction channels was approximately the same, intracellular Na+ concentrations varied from 17 mM in central fiber cells to 7 mM in surface cells, and intracellular voltages varied from −45 mV in central fiber cells to −60 mV in surface cells. Fiber cell membrane conductance was a factor of 2.7 times larger in mouse than in rat lenses. Conclusions. Intracellular hydrostatic pressure is an important physiological parameter that is regulated in lenses from these different species. The most likely mechanism of regulation is to reduce the density of open Na+-leak channels in fiber cells of larger lenses. PMID:23211824

Simulation Analysis of Computer-Controlled pressurization for Mixture Ratio Control

NASA Technical Reports Server (NTRS)

Alexander, Leslie A.; Bishop-Behel, Karen; Benfield, Michael P. J.; Kelley, Anthony; Woodcock, Gordon R.

2005-01-01

A procedural code (C++) simulation was developed to investigate potentials for mixture ratio control of pressure-fed spacecraft rocket propulsion systems by measuring propellant flows, tank liquid quantities, or both, and using feedback from these measurements to adjust propellant tank pressures to set the correct operating mixture ratio for minimum propellant residuals. The pressurization system eliminated mechanical regulators in favor of a computer-controlled, servo- driven throttling valve. We found that a quasi-steady state simulation (pressure and flow transients in the pressurization systems resulting from changes in flow control valve position are ignored) is adequate for this purpose. Monte-Carlo methods are used to obtain simulated statistics on propellant depletion. Mixture ratio control algorithms based on proportional-integral-differential (PID) controller methods were developed. These algorithms actually set target tank pressures; the tank pressures are controlled by another PID controller. Simulation indicates this approach can provide reductions in residual propellants.

40Ar-39Ar laser dating of ductile shear zones from central Corsica (France): Evidence of Alpine (middle to late Eocene) syn-burial shearing in Variscan granitoids

NASA Astrophysics Data System (ADS)

Di Vincenzo, Gianfranco; Grande, Antonietta; Prosser, Giacomo; Cavazza, William; DeCelles, Peter G.

2016-10-01

The island of Corsica (France) plays a central role in any reconstruction of Western Mediterranean geodynamics and paleogeography but several key aspects of its geological evolution are still uncertain. The most debated topics include the interpretation of the Corsican orogen as the result of an east- or west-directed subduction, and the actual involvement of the Variscan basement of Corsica in the Alpine orogenic cycle. This study integrates 40Ar-39Ar laserprobe, mesostructural, microtextural, and microchemical analyses and places relevant constraints on the style, P-T conditions, and timing of Alpine-age, pervasive ductile shear zones which affected the Variscan basement complex of central Corsica, a few kilometers to the west of the present-day front of the Alpine nappes. Shear zones strike NNE-SSW, dip at a high angle, and are characterized by a dominant sinistral strike-slip component. Two of the three investigated shear zones contain two texturally and chemically resolvable generations of white mica, recording a prograde (burial) evolution: (1) deformed celadonite-poor relicts are finely overgrown by (2) a celadonite-rich white mica aligned along the main foliation. White mica from a third sample of another shear zone, characterized by a significantly lower porphyroclast/matrix ratio, exhibits a nearly uniform high-celadonite content, compositionally matching the texturally younger phengite from the nearby shear zones. Mineral-textural analysis, electron microprobe data, and pseudosection modeling constrain P-T conditions attained during shearing at 300 °C and minimum pressures of 0.6 GPa. In-situ 40Ar-39Ar analyses of coexisting low- and high-celadonite white micas from both shear zones yielded a relatively wide range of ages, 45-36 Ma. Laser step-heating experiments gave sigmoidal-shaped age profiles, with step ages in line with in-situ spot dates. By contrast, the apparently chemically homogenous high-celadonite white mica yielded concordant in-situ ages at 34 Ma, but a hump-shaped age spectrum, with maximum ages of 35 Ma and intermediate- to high-temperature steps as young as 33-32 Ma. Results indicate that the studied samples consist of an earlier celadonite-poor white mica with a minimum age of 46 Ma, overgrown by a synshear high-celadonite white mica, developed at greater depth between 37 and 35 Ma; faint late increments in shearing occurred at ≤ 33-32 Ma, when white mica incipiently re-equilibrated during exhumation. Results suggest that ductile shearing with a dominant strike-slip component pervasively deformed the Corsican basement complex during the emplacement and progressive thickening of the Alpine orogenic wedge and broaden the extent of the domain affected by the Alpine tectonometamorphic events. Integration of petrological modeling and geochronological data shows that the Variscan basement of central Corsica, close to the Alpine nappes, was buried during the late Eocene by ≥ 18 km of Alpine orogenic wedge and foreland deposits. Our results, combined with previously published apatite fission-track data, imply an overburden removal ≥ 15 km from the late Eocene (Priabonian) to the early Miocene (Aquitanian), pointing to a minimum average exhumation rate of 1.3-1.5 mm/a.

Introduction of a National Minimum Wage Reduced Depressive Symptoms in Low-Wage Workers: A Quasi-Natural Experiment in the UK.

PubMed

Reeves, Aaron; McKee, Martin; Mackenbach, Johan; Whitehead, Margaret; Stuckler, David

2017-05-01

Does increasing incomes improve health? In 1999, the UK government implemented minimum wage legislation, increasing hourly wages to at least £3.60. This policy experiment created intervention and control groups that can be used to assess the effects of increasing wages on health. Longitudinal data were taken from the British Household Panel Survey. We compared the health effects of higher wages on recipients of the minimum wage with otherwise similar persons who were likely unaffected because (1) their wages were between 100 and 110% of the eligibility threshold or (2) their firms did not increase wages to meet the threshold. We assessed the probability of mental ill health using the 12-item General Health Questionnaire. We also assessed changes in smoking, blood pressure, as well as hearing ability (control condition). The intervention group, whose wages rose above the minimum wage, experienced lower probability of mental ill health compared with both control group 1 and control group 2. This improvement represents 0.37 of a standard deviation, comparable with the effect of antidepressants (0.39 of a standard deviation) on depressive symptoms. The intervention group experienced no change in blood pressure, hearing ability, or smoking. Increasing wages significantly improves mental health by reducing financial strain in low-wage workers. © 2016 The Authors. Health Economics published by John Wiley & Sons Ltd. © 2016 The Authors. Health Economics published by John Wiley & Sons Ltd.

LL and E awarded E and D contract area in eastern Algeria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1992-12-07

This paper reports that a Louisiana Land and Exploration Co. unit has been awarded on exploration and production contract in Algeria by state oil company Enterprise Nationale Sonatrach. LL and E Algeria Ltd.'s contract covers two blocks in the central Ghadames oil basin of eastern Algeria. LL and E said the contract, yet to be submitted for government approval, calls for a minimum investment of $33 million during a 5 year work program that includes seismic acquisition and drilling a minimum of three wildcats.

Ignitability test method and apparatus

NASA Technical Reports Server (NTRS)

Bement, Laurence J. (Inventor); Bailey, James W. (Inventor); Schimmel, Morry L. (Inventor)

1989-01-01

An apparatus for testing ignitability of an initiator includes a body with a central cavity, initiator holder for holding the initiator over the central cavity of the body, an ignition material holder disposed in the central cavity of the body and a cavity facing the initiator holder which receives a measured quantity of ignition material to be ignited by the initiator and a chamber in communication with the cavity of the ignition material holder and the central cavity of the body. A measuring system for analyzing pressure characteristics is generated by ignition material by the initiator. The measuring system includes at least one transducer coupled to an oscillograph for recording pressure traces generated by ignition.

Ignitability test method and apparatus

NASA Technical Reports Server (NTRS)

Bement, Laurence J. (Inventor); Bailey, James W. (Inventor); Schimmel, Morry L. (Inventor)

1991-01-01

An apparatus for testing ignitability of an initiator includes a body having a central cavity, an initiator holder for holding the initiator over the central cavity of the body, an ignition material holder disposed in the central cavity of the body and having a cavity facing the initiator holder which receives a measured quantity of ignition material to be ignited by the initiator. It contains a chamber in communication with the cavity of the ignition material and the central cavity of the body, and a measuring system for analyzing pressure characteristics generated by ignition of the ignition material by the initiator. The measuring system includes at least one transducer coupled with an oscillograph for recording pressure traces generated by ignition.

Composition Dependence of the Hydrostatic Pressure Coefficients of the Bandgap of ZnSe(1-x)Te(x) Alloys

NASA Technical Reports Server (NTRS)

Wu, J.; Yu, K. M.; Walukiewicz, W.; Shan, W.; Ager, J. W., III; Haller, E. E.; Miotkowski, I.; Ramdas, A. K.; Su, Ching-Hua

2003-01-01

Optical absorption experiments have been performed using diamond anvil cells to measure the hydrostatic pressure dependence of the fundamental bandgap of ZnSe(sub 1-xTe(sub x) alloys over the entire composition range. The first and second-order pressure coefficients are obtained as a function of composition. Starting from the ZnSe side, the magnitude of both coefficients increases slowly until x approx. 0.7, where the ambient-pressure bandgap reaches a minimum. For larger values of x the coefficients rapidly approach the values of ZnTe. The large deviations of the pressure coefficients from the linear interpolation between ZnSe and ZnTe are explained in terms of the band anticrossing model.

A universal theory for gas breakdown from microscale to the classical Paschen law

NASA Astrophysics Data System (ADS)

Loveless, Amanda M.; Garner, Allen L.

2017-11-01

While well established for larger gaps, Paschen's law (PL) fails to accurately predict breakdown for microscale gaps, where field emission becomes important. This deviation from PL is characterized by the absence of a minimum breakdown voltage as a function of the product of pressure and gap distance, which has been demonstrated analytically for microscale and smaller gaps with no secondary emission at atmospheric pressure [A. M. Loveless and A. L. Garner, IEEE Trans. Plasma Sci. 45, 574-583 (2017)]. We extend these previous results by deriving analytic expressions that incorporate the nonzero secondary emission coefficient, γS E, that are valid for gap distances larger than those at which quantum effects become important (˜100 nm) while remaining below those at which streamers arise. We demonstrate the validity of this model by benchmarking to particle-in-cell simulations with γSE = 0 and comparing numerical results to an experiment with argon, while additionally predicting a minimum voltage that was masked by fixing the gap pressure in previous analyses. Incorporating γSE demonstrates the smooth transition from field emission dominated breakdown to the classical PL once the combination of electric field, pressure, and gap distance satisfies the conventional criterion for the Townsend avalanche; however, such a condition generally requires supra-atmospheric pressures for breakdown at the microscale. Therefore, this study provides a single universal breakdown theory for any gas at any pressure dominated by field emission or Townsend avalanche to guide engineers in avoiding breakdown when designing microscale and larger devices, or inducing breakdown for generating microplasmas.

Ignition Delay of Combustible Materials in Normoxic Equivalent Environments

NASA Technical Reports Server (NTRS)

McAllister, Sara; Fernandez-Pello, Carlos; Ruff, Gary; Urban, David

2009-01-01

Material flammability is an important factor in determining the pressure and composition (fraction of oxygen and nitrogen) of the atmosphere in the habitable volume of exploration vehicles and habitats. The method chosen in this work to quantify the flammability of a material is by its ease of ignition. The ignition delay time was defined as the time it takes a combustible material to ignite after it has been exposed to an external heat flux. Previous work in the Forced Ignition and Spread Test (FIST) apparatus has shown that the ignition delay in the currently proposed space exploration atmosphere (approximately 58.6 kPa and32% oxygen concentration) is reduced by 27% compared to the standard atmosphere used in the Space Shuttle and Space Station. In order to determine whether there is a safer environment in terms of material flammability, a series of piloted ignition delay tests using polymethylmethacrylate (PMMA) was conducted in the FIST apparatus to extend the work over a range of possible exploration atmospheres. The exploration atmospheres considered were the normoxic equivalents, i.e. reduced pressure conditions with a constant partial pressure of oxygen. The ignition delay time was seen to decrease as the pressure was reduced along the normoxic curve. The minimum ignition delay observed in the normoxic equivalent environments was nearly 30% lower than in standard atmospheric conditions. The ignition delay in the proposed exploration atmosphere is only slightly larger than this minimum. Interms of material flammability, normoxic environments with a higher pressure relative to the proposed pressure would be desired.

Infusion of noradrenaline through the proximal line of a migrated central venous catheter.

PubMed

Freer, M; Noble, S

2012-08-01

A 41-year-old, obese, patient was admitted to Accident and Emergency with a history of leg cellulitis. A central line was inserted. Documented aspiration of blood from all lines, central venous pressure trace obtained and correct position noted on the chest X-ray (CXR). The patient became increasingly septic despite antibiotic therapy. He was subsequently commenced on a noradrenaline infusion; however, the blood pressure was unresponsive. On admission to the intensive care unit (ICU), it was noted he had an area of white skin over the right clavicle. The infusions were stopped and a CXR confirmed proximal migration of the line. The central line was re-sited and his noradrenaline recommenced with an improvement in his blood pressure. Acute renal failure developed which required haemofiltration for 24 hours. The condition improved and the patient was discharged from ICU. It took several weeks for his renal function to return to normal, but he was discharged home with no permanent damage.

46 CFR 38.10-10 - Cargo piping-TB/ALL.

Code of Federal Regulations, 2012 CFR

2012-10-01

... pressure shall be seamless drawn steel or electric resistance welded steel. Pipe used in refrigerated tank systems shall be of a material which is suitable for the minimum service temperature to which it may be...

46 CFR 38.10-10 - Cargo piping-TB/ALL.

Code of Federal Regulations, 2014 CFR

2014-10-01

... pressure shall be seamless drawn steel or electric resistance welded steel. Pipe used in refrigerated tank systems shall be of a material which is suitable for the minimum service temperature to which it may be...

46 CFR 38.10-10 - Cargo piping-TB/ALL.

Code of Federal Regulations, 2011 CFR

2011-10-01

... pressure shall be seamless drawn steel or electric resistance welded steel. Pipe used in refrigerated tank systems shall be of a material which is suitable for the minimum service temperature to which it may be...

46 CFR 38.10-10 - Cargo piping-TB/ALL.

Code of Federal Regulations, 2013 CFR

2013-10-01

... pressure shall be seamless drawn steel or electric resistance welded steel. Pipe used in refrigerated tank systems shall be of a material which is suitable for the minimum service temperature to which it may be...

Laparoscopic umbilical hernia repair in a cirrhotic patient with a peritoneovenous shunt.

PubMed

Umemura, Akira; Suto, Takayuki; Sasaki, Akira; Fujita, Tomohiro; Endo, Fumitaka; Wakabayashi, Go

2015-05-01

A 62-year-old Japanese woman who had developed massive cirrhotic ascites was referred to our hospital for a peritoneovenous shunt implant. However, CT examination revealed an umbilical hernia that had not been observed before the peritoneovenous shunt was implanted. We decided to perform laparoscopic umbilical hernia repair to keep carbon dioxide from flowing backward into the central circulatory system. We first clamped the catheter and set the upper limit of the pneumoperitoneum pressure to 6 mmHg. The central venous pressure was also measured simultaneously. Mesh was then applied over the hernia and fixed by the double-crown technique. Finally, 1000-mL physiological saline was infused into the abdominal cavity while the pneumoperitoneum was slowly released. In this case, we safely performed laparoscopic umbilical hernia repair while making some alterations, specifically catheter clamping, reducing pneumoperitoneum pressure, monitoring central venous pressure, and infusing physiological saline. © 2014 Japan Society for Endoscopic Surgery, Asia Endosurgery Task Force and Wiley Publishing Asia Pty Ltd.

Geometry and starvation effects in hydrodynamic lubrication

NASA Technical Reports Server (NTRS)

Brewe, D.; Hamrock, B. J.

1982-01-01

Numerical methods were used to detemine the effects of lubricant starvation on the minimum film thickness under conditions of a hydrodynamic point contact. Starvation was effected by varying the fluid inlet level. The Reynolds boundary conditions were applied at the cavitation boundary and zero pressure was stipulated at the meniscus or inlet boundary. A minimum film thickness equation as a function of both the ratio of dimensionless load to dimensionless speed and inlet supply level was determined. By comparing the film generated under the starved inlet condition with the film generated from the fully flooded inlet, an expression for the film reduction factor was obtained. Based on this factor a starvation threshold was defined as well as a critically starved inlet. The changes in the inlet pressure buildup due to changing the available lubricant supply are presented in the form of three dimensional isometric plots and also in the form of contour plots.

Torsional shear flow of granular materials: shear localization and minimum energy principle

NASA Astrophysics Data System (ADS)

Artoni, Riccardo; Richard, Patrick

2018-01-01

The rheological properties of granular matter submitted to torsional shear are investigated numerically by means of discrete element method. The shear cell is made of a cylinder filled by grains which are sheared by a bumpy bottom and submitted to a vertical pressure which is applied at the top. Regimes differing by their strain localization features are observed. They originate from the competition between dissipation at the sidewalls and dissipation in the bulk of the system. The effects of the (i) the applied pressure, (ii) sidewall friction, and (iii) angular velocity are investigated. A model, based on the purely local μ (I)-rheology and a minimum energy principle is able to capture the effect of the two former quantities but unable to account the effect of the latter. Although, an ad hoc modification of the model allows to reproduce all the numerical results, our results point out the need for an alternative rheology.

Determination of parameters used to prevent ignition of stored materials and to protect against explosions in food industries.

PubMed

Ramírez, Alvaro; García-Torrent, Javier; Aguado, Pedro J

2009-08-30

There are always risks associated with silos when the stored material has been characterized as prone to self-ignition or explosion. Further research focused on the characterization of agricultural materials stored in silos is needed due to the lack of data found in the literature. The aim of this study was to determine the ignitability and explosive parameters of several agricultural products commonly stored in silos in order to assess the risk of ignition and dust explosion. Minimum Ignition Temperature, with dust forming a cloud and deposited in a layer, Lower Explosive Limit, Minimum Ignition Energy, Maximum Explosion Pressure and Maximum Explosion Pressure Rise were determined for seven agricultural materials: icing sugar, maize, wheat and barley grain dust, alfalfa, bread-making wheat and soybean dust. Following characterization, these were found to be prone to producing self-ignition when stored in silos under certain conditions.

Analysis of starvation effects on hydrodynamic lubrication in nonconforming contacts

NASA Technical Reports Server (NTRS)

Brewe, D. E.; Hamrock, B. J.

1981-01-01

Numerical methods were used to determine the effects of lubricant starvation on the minimum film thickness under conditions of a hydrodynamic point contact. Starvation was effected by varying the fluid inlet level. The Reynolds boundary conditions were applied at the cavitation boundary and zero pressure was stipulated at the meniscus or inlet boundary. A minimum-fill-thickness equation as a function of both the ratio of dimensionless load to dimensionless speed and inlet supply level was determined. By comparing the film generated under the starved inlet condition with the film generated from the fully flooded inlet, an expression for the film reduction factor was obtained. Based on this factor a starvation threshold was defined as well as a critically starved inlet. The changes in the inlet pressure buildup due to changing the available lubricant supply are presented in the form of three dimensional isometric plots and also in the form of contour plots.

Geometry and starvation effects in hydrodynamic lubrication

NASA Technical Reports Server (NTRS)

Brewe, D. E.; Hamrock, B. J.

1982-01-01

Numerical methods were used to determine the effects of lubricant starvation on the minimum film thickness under conditions of a hydrodynamic point contact. Starvation was effected by varying the fluid inlet level. The Reynolds boundary conditions were applied at the cavitation boundary and zero pressure was stipulated at the meniscus or inlet boundary. A minimum-film-thickness equation as a function of both the ratio of dimensionless load to dimensionless speed and inlet supply level was determined. By comparing the film generated under the starved inlet condition with the film generated from the fully flooded inlet, an expression for the film reduction factor was obtained. Based on this factor a starvation threshold was defined as well as a critically starved inlet. The changes in the inlet pressure buildup due to changing the available lubricant supply are presented in the form of three dimensional isometric plots and also in the form of contour plots.

Numerical investigation on the expansion of supercritical carbon dioxide jet

NASA Astrophysics Data System (ADS)

Lv, Q.; Long, X. P.; Kang, Y.; Xiao, L. Z.; Wu, W.

2013-12-01

Supercritical carbon dioxide (SC-CO2) fluid is characterized by low rock breaking threshold pressure and high rock breaking rate. Meanwhile, SC-CO2 fluid has relatively low viscosity near to gas and high density near to liquid. So, it has great advantages in drilling and rock breaking over water. In this paper, numerical study of SC-CO2 flowing through a nozzle is presented. The purpose of this simulation is to ascertain why the SC-CO2 jet flow has better ability in drilling and rock breaking than the water jet flow. The simulation model was controlled by the RANS equations together with the continuity equation as well as the energy equation. The realizable k-epsilon turbulence model was adopted to govern the turbulent characteristics. Pressure boundary conditions were applied to the inlet and outlet boundary. The properties of carbon dioxide and water were described by UDF. It is found that: (1) under the same boundary conditions, the decay of dimensionless central axial velocity and dynamic pressure of water is quicker than that of the SC-CO2, and the core length of SC-CO2 jet is about 4.5 times of the nozzle diameter, which is 1 times longer than that of the water; (2) With the increase of inlet pressure or the decrease of outlet pressure, the dimensionless central axial velocity and dynamic pressure attenuation of water keeps the same, while the decay of central axial velocity of SC-CO2 turns gentle; (3) the change of central axial temperature of SC-CO2 is more complex than that of the water.

B-Type Natriuretic Peptide Reactivity to Mental Stress and Exercise: Role of Obesity and Hemodynamics

DTIC Science & Technology

2009-08-25

both of which increase SV and CO (Figure 16). Specifically, circulating catecholamines decrease venous compliance and increase central venous pressure...t Inotropy t Central Venous Pressure , t Preload / t SV&CO 104 References 1. The Criteria Committee of the New York Heart Association...Science Degrees -Public Health Masters Degrees -Military Medical History -Public Health -Tropical Medicine & Hygiene Graduate Education Office

Theoretical detection threshold of the proton-acoustic range verification technique.

PubMed

Ahmad, Moiz; Xiang, Liangzhong; Yousefi, Siavash; Xing, Lei

2015-10-01

Range verification in proton therapy using the proton-acoustic signal induced in the Bragg peak was investigated for typical clinical scenarios. The signal generation and detection processes were simulated in order to determine the signal-to-noise limits. An analytical model was used to calculate the dose distribution and local pressure rise (per proton) for beams of different energy (100 and 160 MeV) and spot widths (1, 5, and 10 mm) in a water phantom. In this method, the acoustic waves propagating from the Bragg peak were generated by the general 3D pressure wave equation implemented using a finite element method. Various beam pulse widths (0.1-10 μs) were simulated by convolving the acoustic waves with Gaussian kernels. A realistic PZT ultrasound transducer (5 cm diameter) was simulated with a Butterworth bandpass filter with consideration of random noise based on a model of thermal noise in the transducer. The signal-to-noise ratio on a per-proton basis was calculated, determining the minimum number of protons required to generate a detectable pulse. The maximum spatial resolution of the proton-acoustic imaging modality was also estimated from the signal spectrum. The calculated noise in the transducer was 12-28 mPa, depending on the transducer central frequency (70-380 kHz). The minimum number of protons detectable by the technique was on the order of 3-30 × 10(6) per pulse, with 30-800 mGy dose per pulse at the Bragg peak. Wider pulses produced signal with lower acoustic frequencies, with 10 μs pulses producing signals with frequency less than 100 kHz. The proton-acoustic process was simulated using a realistic model and the minimal detection limit was established for proton-acoustic range validation. These limits correspond to a best case scenario with a single large detector with no losses and detector thermal noise as the sensitivity limiting factor. Our study indicated practical proton-acoustic range verification may be feasible with approximately 5 × 10(6) protons/pulse and beam current.

Theoretical detection threshold of the proton-acoustic range verification technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmad, Moiz; Yousefi, Siavash; Xing, Lei, E-mail: lei@stanford.edu

2015-10-15

Purpose: Range verification in proton therapy using the proton-acoustic signal induced in the Bragg peak was investigated for typical clinical scenarios. The signal generation and detection processes were simulated in order to determine the signal-to-noise limits. Methods: An analytical model was used to calculate the dose distribution and local pressure rise (per proton) for beams of different energy (100 and 160 MeV) and spot widths (1, 5, and 10 mm) in a water phantom. In this method, the acoustic waves propagating from the Bragg peak were generated by the general 3D pressure wave equation implemented using a finite element method.more » Various beam pulse widths (0.1–10 μs) were simulated by convolving the acoustic waves with Gaussian kernels. A realistic PZT ultrasound transducer (5 cm diameter) was simulated with a Butterworth bandpass filter with consideration of random noise based on a model of thermal noise in the transducer. The signal-to-noise ratio on a per-proton basis was calculated, determining the minimum number of protons required to generate a detectable pulse. The maximum spatial resolution of the proton-acoustic imaging modality was also estimated from the signal spectrum. Results: The calculated noise in the transducer was 12–28 mPa, depending on the transducer central frequency (70–380 kHz). The minimum number of protons detectable by the technique was on the order of 3–30 × 10{sup 6} per pulse, with 30–800 mGy dose per pulse at the Bragg peak. Wider pulses produced signal with lower acoustic frequencies, with 10 μs pulses producing signals with frequency less than 100 kHz. Conclusions: The proton-acoustic process was simulated using a realistic model and the minimal detection limit was established for proton-acoustic range validation. These limits correspond to a best case scenario with a single large detector with no losses and detector thermal noise as the sensitivity limiting factor. Our study indicated practical proton-acoustic range verification may be feasible with approximately 5 × 10{sup 6} protons/pulse and beam current.« less