Area and Pressure Profiles for Collapsible-Tube Oscillations of Three Types

(1) Background: Cardiovascular autonomic dysfunction is a non-motor feature in Parkinson’s disease with negative impact on functionality and life expectancy, prompting early detection and proper management. We aimed to describe the blood pressure patterns reported in patients with Parkinson’s disease, as measured by 24-h ambulatory blood pressure monitoring. (2) Methods: We conducted a systematic search on the PubMed database. Studies enrolling patients with Parkinson’s disease undergoing 24-h ambulatory blood pressure monitoring were included. Data regarding study population, Parkinson’s disease course, vasoactive drugs, blood pressure profiles, and measurements were recorded. (3) Results: The search identified 172 studies. Forty studies eventually fulfilled the inclusion criteria, with 3090 patients enrolled. Abnormal blood pressure profiles were commonly encountered: high blood pressure in 38.13% of patients (938/2460), orthostatic hypotension in 38.68% (941/2433), supine hypertension in 27.76% (445/1603) and nocturnal hypertension in 38.91% (737/1894). Dipping status was also altered often, 40.46% of patients (477/1179) being reverse dippers and 35.67% (310/869) reduced dippers. All these patterns were correlated with negative clinical and imaging outcomes. (4) Conclusion: Patients with Parkinson’s disease have significantly altered blood pressure patterns that carry a negative prognosis. Ambulatory blood pressure monitoring should be validated as a biomarker of PD-associated cardiovascular dysautonomia and a tool for assisting therapeutic interventions.

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Study of Correctly Expanded Sonic Jet with Air Tabs

International Journal of Turbo and Jet Engines ◽

10.1515/tjj-2020-0005 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Arun Prasad R ◽

Thanigaiarasu S ◽

Sembaruthi M ◽

Rathakrishnan E

Keyword(s):

Numerical Study ◽

Cross Sectional ◽

Potential Core ◽

Convergent Nozzle ◽

Jet Mixing ◽

Pressure Profiles ◽

Constant Diameter ◽

Sonic Jet ◽

Sectional Shape ◽

Length Reduction

AbstractThe present numerical study is to understand the effect of air tabs located at the exit of a convergent nozzle on the spreading and mixing characteristics of correctly expanded sonic primary jet. Air tabs used in this study are two secondary jets issuing from constant diameter tubes located diametrically opposite at the periphery of the primary nozzle exit, normal to the primary jet. Two air tabs of Mach numbers 1.0 to 1.4, in steps of 0.1 are considered in this study. The mixing modification caused by air tabs are analysed by considering the mixing of uncontrolled (free) primary jet as a reference. Substantial enhancement in jet mixing is achieved with Mach 1.4 air tabs, which results in 80 % potential core length reduction. The total pressure profiles taken on the plane (YZ) normal to the primary jet axis, at various locations along the primary jet centreline revealed the modification of the jet cross sectional shape by air tabs. The stream-wise vortices and bifurcation of the primary jet caused by air tabs are found to be the mechanism behind the enhanced jet mixing.

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Blood Pressure Profiles and Cognitive Function from Adulthood to Old Age: Chasing a Golden Middle Way?

Journal of Clinical Medicine ◽

10.3390/jcm10153243 ◽

2021 ◽

Vol 10 (15) ◽

pp. 3243

Author(s):

Rita Del Pinto ◽

Davide Grassi ◽

Raffaella Bocale ◽

Francesco Carubbi ◽

Claudio Ferri ◽

...

Keyword(s):

Cognitive Impairment ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Demographic Shift ◽

Antihypertensive Medications ◽

Microvascular Damage ◽

Middle Way ◽

Alzheimer Type Dementia ◽

Age Related ◽

Pressure Profiles

With the demographic shift toward advanced ages, it is imperative to understand the biological mechanisms behind common, disabling age-related diseases such as cognitive impairment in its mild form to overt dementia. Hypertension, a major cardiovascular risk factor, is epidemiologically linked to vascular and Alzheimer-type dementia, with possible mechanisms being atherosclerotic macro- and microvascular damage leading to neuronal cell death, as well as proinflammatory events responsible for neurodegeneration. Nevertheless, there is currently a knowledge gap as to which population to target, what the diagnostics test, and how to manage early pathogenic events in order to prevent such a dramatic and disabling condition. While clinical trials data support the benefit of active BP control with antihypertensive medications on the risk of future cognitive impairment, hypotension appears to be related to accelerated cognitive decline in both the fit and the cognitively frail elderly. Dedicated, technologically advanced studies assessing the relation of BP with dementia are needed to clarify the pathophysiological mechanisms in the association before a tailored preventive, diagnostic, and therapeutic approach to one of the most widespread modern medical challenges becomes a reality.

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Investigation of a Tip Clearance Cascade in a Water Analogy Rig

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.3239883 ◽

1986 ◽

Vol 108 (1) ◽

pp. 38-46 ◽

Cited By ~ 11

Author(s):

J. A. H. Graham

Keyword(s):

Turbine Blades ◽

Flow Region ◽

Tip Clearance ◽

Turbine Engines ◽

Gas Turbine Engines ◽

Tip Clearance Flow ◽

Pressure Profiles ◽

Clearance Flow ◽

Hot Film ◽

Model Features

The tip clearance flow region of high-pressure axial turbine blades for small gas turbine engines has been investigated in a water flow cascade. The blade model features variable clearance and variable endwall speeds. The cascade is scaled for Reynolds number and sized to give velocities suitable for visualization. Pressure profiles were measured on one blade, and correlated with the visualization. Unloading is found to be a major feature of the pressure field at both tip and midspan, and is intimately connected with scraping effects and the behavior of the clearance vortex. Some initial hot-film velocity measurements are also presented.

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THE IMPACT OF OBESITY ON AMBULATORY BLOOD PRESSURE PROFILES IN HYPERTENSIVE SUBJECTS IS AGE DEPENDENT: PP.3.104

Journal of Hypertension ◽

10.1097/01.hjh.0000378428.73242.f3 ◽

2010 ◽

Vol 28 ◽

pp. e79

Author(s):

S Hoshide ◽

Y Yano ◽

M Shimizu ◽

T Kabutoya ◽

Y Matsui ◽

...

Keyword(s):

Blood Pressure ◽

Ambulatory Blood Pressure ◽

Pressure Profiles ◽

Age Dependent ◽

The Impact

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Validating Numerical CFD Simulations With Experimental Data for Turbulence Phenomena in Axial Flow Gas Turbine Diffusers

Volume 7: Turbomachinery, Parts A and B ◽

10.1115/gt2009-59086 ◽

2009 ◽

Author(s):

Farrokh Zarifi-Rad ◽

Hamid Vajihollahi ◽

James O’Brien

Keyword(s):

Experimental Data ◽

Gas Turbine ◽

Turbine Blades ◽

Axial Flow ◽

Experimental Results ◽

Scale Model ◽

Data Set ◽

Pressure Profiles ◽

Scale Models ◽

Inlet Conditions

Scale models give engineers an excellent understanding of the aerodynamic behavior behind their design; nevertheless, scale models are time consuming and expensive. Therefore computer simulations such as Computational Fluid Dynamics (CFD) are an excellent alternative to scale models. One must ask the question, how close are the CFD results to the actual fluid behavior of the scale model? In order to answer this question the engineering team investigated the performance of a large industrial Gas Turbine (GT) exhaust diffuser scale model with performance predicted by commercially available CFD software. The experimental results were obtained from a 1:12 scale model of a GT exhaust diffuser with a fixed row of blades to simulate the swirl generated by the last row of turbine blades five blade configurations. This work is to validate the effect of the turbulent inlet conditions on an axial diffuser, both on the experimental front and on the numerical analysis approach. The object of this work is to bring forward a better understanding of velocity and static pressure profiles along the gas turbine diffusers and to provide an accurate experimental data set to validate the CFD prediction. For the CFD aspect, ANSYS CFX software was chosen as the solver. Two different types of mesh (hexagonal and tetrahedral) will be compared to the experimental results. It is understood that hexagonal (HEX) meshes are more time consuming and more computationally demanding, they are less prone to mesh sensitivity and have the tendancy to converge at a faster rate than the tetrahedral (TET) mesh. It was found that the HEX mesh was able to generate more consistent results and had less error than TET mesh.

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Propagation of radiosonde pressure sensor errors to ozonesonde measurements

Atmospheric Measurement Techniques ◽

10.5194/amt-7-65-2014 ◽

2014 ◽

Vol 7 (1) ◽

pp. 65-79 ◽

Cited By ~ 21

Author(s):

R. M. Stauffer ◽

G. A. Morris ◽

A. M. Thompson ◽

E. Joseph ◽

G. J. R. Coetzee ◽

...

Keyword(s):

Pressure Sensor ◽

Atmospheric Pressure ◽

Pressure Profile ◽

Mixing Ratio ◽

Concentration Cell ◽

Pressure Profiles ◽

Dependent Variables ◽

Sensor Errors ◽

Subsequent Addition ◽

Total Column

Abstract. Several previous studies highlight pressure (or equivalently, pressure altitude) discrepancies between the radiosonde pressure sensor and that derived from a GPS flown with the radiosonde. The offsets vary during the ascent both in absolute and percent pressure differences. To investigate this problem further, a total of 731 radiosonde/ozonesonde launches from the Southern Hemisphere subtropics to northern mid-latitudes are considered, with launches between 2005 and 2013 from both longer term and campaign-based intensive stations. Five series of radiosondes from two manufacturers (International Met Systems: iMet, iMet-P, iMet-S, and Vaisala: RS80-15N and RS92-SGP) are analyzed to determine the magnitude of the pressure offset. Additionally, electrochemical concentration cell (ECC) ozonesondes from three manufacturers (Science Pump Corporation; SPC and ENSCI/Droplet Measurement Technologies; DMT) are analyzed to quantify the effects these offsets have on the calculation of ECC ozone (O3) mixing ratio profiles (O3MR) from the ozonesonde-measured partial pressure. Approximately half of all offsets are > ±0.6 hPa in the free troposphere, with nearly a third > ±1.0 hPa at 26 km, where the 1.0 hPa error represents ~ 5% of the total atmospheric pressure. Pressure offsets have negligible effects on O3MR below 20 km (96% of launches lie within ±5% O3MR error at 20 km). Ozone mixing ratio errors above 10 hPa (~ 30 km), can approach greater than ±10% (> 25% of launches that reach 30 km exceed this threshold). These errors cause disagreement between the integrated ozonesonde-only column O3 from the GPS and radiosonde pressure profile by an average of +6.5 DU. Comparisons of total column O3 between the GPS and radiosonde pressure profiles yield average differences of +1.1 DU when the O3 is integrated to burst with addition of the McPeters and Labow (2012) above-burst O3 column climatology. Total column differences are reduced to an average of −0.5 DU when the O3 profile is integrated to 10 hPa with subsequent addition of the O3 climatology above 10 hPa. The RS92 radiosondes are superior in performance compared to other radiosondes, with average 26 km errors of −0.12 hPa or +0.61% O3MR error. iMet-P radiosondes had average 26 km errors of −1.95 hPa or +8.75 % O3MR error. Based on our analysis, we suggest that ozonesondes always be coupled with a GPS-enabled radiosonde and that pressure-dependent variables, such as O3MR, be recalculated/reprocessed using the GPS-measured altitude, especially when 26 km pressure offsets exceed ±1.0 hPa/±5%.

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