1,145 results on '"Mean pressure"'
Search Results
2. Investigating the Impact of Cumulative Pressure-Induced Stress on Machine Learning Models for Pipe Breaks.
- Author
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Konstantinou, Charalampos, Jara-Arriagada, Carlos, and Stoianov, Ivan
- Subjects
MACHINE learning ,DYNAMIC pressure ,STATIC pressure ,FAILURE mode & effects analysis ,RANDOM forest algorithms ,WATER pressure ,PIPE - Abstract
Significant financial resources are needed for the maintenance and rehabilitation of water supply networks (WSNs) to prevent pipe breaks. The causes and mechanisms for pipe breaks vary between different WSNs. However, it is commonly acknowledged that the operational management and water pressure influence significantly the frequency of pipe breaks. Pipe breaks occur when the water pressure exceeds the tensile strength of a pipe, or due to repetitive pressure cycles that result in fatigue-related failures. Considering these pipe failure modes, a new metric known as cumulative pressure-induced stress has been introduced. This metric takes into account both static and dynamic pressure components that contribute to pipe breaks, including mean pressure and the magnitude and frequency of pressure fluctuations, respectively. The impact of CPIS on pipe breaks has not been extensively investigated. Consequently, this study investigates and evaluates the impact of this metric when incorporated as an explanatory variable in Random Forest (RF) models that analyse the key causes of pipe breaks in two WSNs. Different RF models were developed both with and without incorporating pressure components. Subsequently, the performance of these models and the significance of each input variable were assessed. The results of this study suggest that CPIS is an important variable, especially in cases where pressure-related factors play a significant role in pipe breaks. Consequently, incorporating CPIS has shown a notable improvement in the accuracy of pipe break models. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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- View/download PDF
3. A Historical Journey on the Physiology of Blood Pressure Monitoring
- Author
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Adji, Audrey, O’Rourke, Michael F., Solà, Josep, editor, and Delgado-Gonzalo, Ricard, editor
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- 2019
- Full Text
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4. Prediction of Temperature Difference across Thermoacoustic Stack through Artificial Neural Network Technique.
- Author
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Rahman, Anas A. and Xiaoqing Zhang
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ARTIFICIAL neural networks ,STANDING waves ,SYSTEM identification ,TEMPERATURE - Abstract
This study involved the application of an artificial neural network (ANN) as a new approach for thermoacoustic refrigerators to predict the temperature difference across the stack under some operating conditions. One ANN model for a standing wave thermoacoustic refrigerator had been developed based on the experimental data from other literature. The temperature difference across the stack was chosen as a response to the input parameters, mean pressure, and frequency in the proposed ANN model. A multi-layer feed-forward neural network with a backpropagation algorithm had been proposed for predicting the temperature difference across the stack of the thermoacoustic refrigerator. This proposed ANN model has three layers with configuration 2-12-1, namely, the input layer with two neurons representing the two operating parameters, one hidden layer with an optimal 12 hidden neurons, and the output layer with one neuron representing the temperature difference across the stack, as a response. The high ability of ANN for data prediction was proven in this study by achieving an average prediction error of 0.2% and a regression coefficient (R) of 0.99979 during the testing phase. This research work provides a new approach based on the ANN technique to solve complex thermoacoustic problems with linear or nonlinear nature through either modeling, optimization, or system identification. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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5. Dynamic Loading Assessment at the Fifth Metatarsal in Elite Athletes With a History of Jones Fracture.
- Author
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Hunt, Kenneth J., Goeb, Yannick, and Bartolomei, Jonathan
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RUNNING , *JONES fracture , *METATARSUS , *DESCRIPTIVE statistics , *WALKING , *BIOMECHANICS , *WEIGHT-bearing (Orthopedics) - Abstract
Supplemental Digital Content is Available in the Text. Objective: We hypothesize that athletes who have suffered Jones fractures will apply significantly higher loads at the fifth metatarsal base during athletic activities compared with matched uninjured athletes. Design: Sixteen athletes were recruited to participate. Eight athletes had a history of Jones fracture, and 8 age, gender, and position-matched athletes without a history of foot injury were recruited as controls. Setting: Institutional study at Stanford University. Participants: Sixteen athletes with/without a history of foot injury from Stanford University. Interventions: Athletes performed a standardized series of movements while wearing calibrated, wireless pressure mapping insoles, and then again with their custom corrective insoles. Main Outcome Measures: Peak pressure, mean pressure, maximum force, and force-time integral (ie, impulse) were recorded for each activity. Results: Athletes with a history of Jones fracture showed a significantly increased peak pressure (183 ± 23 vs 138 ± 7 kPA), mean pressure (124 ± 14 vs 95 ± 4 kPA), and maximum force (15 ± 1.2 vs 12 ± 1.2%BW) at the fifth metatarsal base during walking and running compared with uninjured matched controls (all P < 0.05). Conclusions: Athletes with a history of Jones fracture exert significantly increased peak and mean forces at the base of the fifth metatarsal during common athletic activities. Custom orthoses do not seem to offload this region in all cases. Increased loads may contribute to the development of stress injury to the fifth metatarsal during repetitive loading, and ultimately fracture of the bone. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
6. Study of Vortex Breakdown and Pitch up on a Compound Delta Wing
- Author
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SHIVAM and Shashi Bhushan VERMA
- Subjects
Compound Delta ta Wing ,vortex breakdown ,pitch up ,Delta wing ,Mean pressure ,Motor vehicles. Aeronautics. Astronautics ,TL1-4050 - Abstract
This paper discusses the calculation of mean pressure on a compound delta wing configuration and its variance to understand vortex breakdown and pitch up on the setup. The configuration of the compound delta wing being used was 50°-60°. The data was used to find the location of vortex breakdown and pitch up over the compound delta wing. It was done using calibration of different pressure ports on span and chord wise location of the wing. The pressure values were then converted to Coefficient of Pressure (Cp) for proper study and comparison.
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- 2019
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7. Pedobarography: a novel approach to test the efficacy of treatments for lameness; an experience with mavacoxib in dogs with elbow osteoarthritis
- Author
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Sergio López, José M. Vilar, Mónica Rubio, Joaquín J. Sopena, Angelo Santana, Oliver Rodríguez, José A. Rodríguez-Altonaga, and José M. Carrillo
- Subjects
Balance ,Pedobarography ,Dog ,Mean pressure ,Peak pressure ,Paw ,Veterinary medicine ,SF600-1100 - Abstract
Abstract Background Pedobarographic analyses detect pressure redistribution among limbs and within limbs in humans, equids and dogs. The main objective of this study was to assess the usefulness of a set of pedobarographic parameters for the detection of lameness, as well as for its suitability for assessing the effects of therapies against osteoarthritis in dogs. With this purpose, eleven large-breed lame dogs with unilateral osteoarthritis due to elbow dysplasia were evaluated using a pressure platform prior to (D0) and after 3 months (D90) of treatment with mavacoxib, a COX-2 selective NSAID. The obtained parameters were: pressure distribution between lame and sound limbs, as well as paw area, mean pressure, and peak pressure of both lame and sound limbs. Results The results showed statistical differences in all these parameters between lame and sound limbs at D0; however, at D90, differences were significantly decreased as result of the treatment, indicating a substantial functional recovery under the study design conditions. Conclusions The provided data prove the suitability of this novel technique in canine models for the quantitative and objective assessment of lameness, but also for the evaluation of treatments for lameness caused by articular pain.
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- 2019
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8. Numerical Study on the Effect of Mean Pressure and Loop's Radius to the Onset Temperature and Efficiency of Traveling Wave Termoacustic Engine
- Author
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Endang Dian Rokhmawati, Irna Farikhah, Ummi Kaltsum, Harto Nuroso, Aan Burhanudin, Yuris Setyoadi, Muhammad Amiruddin, and Irfan Abd Rahim
- Subjects
Mean Pressure ,Loop's Radius ,Thermoacoustic Engine ,Mechanical engineering and machinery ,TJ1-1570 ,Mechanics of engineering. Applied mechanics ,TA349-359 - Abstract
The thermoacoustic engine can be a device to convert waste heat energy in the engine car become useful energy such as for charging battery in car or Air conditioner of the car. This work can be done by experimentally and numerically. There are some parameters that have an impact on the performance of the engine. They are geometry of the engines, working fluid, and mean pressure. The performance of the engine depends on the efficiency and the heating temperature. In the car, waste heat energy is not high enough. Therefore, we need to utilize the low heating temperature to be converted into useful energy. This study contributes to numerically the effect of mean pressure and loop’s radius of the regenerator on the onset temperature and the efficiency of traveling wave thermoacoustic engines. The application that is used to solve numerical problems is fortran95. There are two codings that are used in fortran95. They are stability limits and efficiency codes. The lowest onset temperature that achieved is 153˚C with efficiency up to 38.1% that can be reached when the mean pressure is 4.0 MPa and the loop's radius is 5 cm. This result indicated that we can use low heating temperatures from waste heat of engine car to turn on electronics equipment inside the car.
- Published
- 2020
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9. Flow around a Circular Cylindrical Shell.
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Khakimov, A. G.
- Subjects
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CYLINDRICAL shells , *AERODYNAMIC load , *BENDING moment , *VELOCITY , *FLUID dynamics - Abstract
The results of the simulation of separationless jet flow around an elastic cylindrical shell under nonlinear boundary conditions are presented. The mean pressure action on the shell is taken into account. The solution is obtained in the form of series in the powers of the aerohydroelasticity parameter. The shapes of the shell cross-section, the pressure distributions over the deformed and undeformed shell, the distribution of the dimensionless bending moment, and the shear and tension forces are presented. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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10. The Effect of 3 Foot Pads on Plantar Pressure of Pes Planus Foot Type.
- Author
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Nordsiden, Lacey, van Lunen, Bonnie L., Walker, Martha L., Cortes, Nelson, Pasquale, Maria, and Onate, James A.
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PLANTAR fasciitis , *METATARSUS , *FOOT diseases , *FOOT manifestations of general diseases , *PHYSICAL education , *TREADMILL exercise , *PRESSURE measurement , *HEALTH outcome assessment , *JONES fracture - Abstract
Context: Many styles of foot pads are commonly applied to reduce immediate pain and pressure under the foot. Objective: To examine the effect of 3 different foot pads on peak plantar pressure (PPP) and mean plantar pressure (MPP) under the first metatarsophalangeal joint (MTPJ) during slow running. Design: A 4 (pad) × 4 (mask) repeated-measures design. Setting: University athletic training clinic and fitness facility. Participants: 20 physically active participants, 12 men (19.7 ± 1.3 y, 181.5 ± 6.3 cm, 83.6 ± 12.3 kg) and 8 women (20.8 ± 1.5 y, 172.7 ± 11.2 cm, 69.9 ± 14.2 kg) with navicular drop greater than or equal to 10 mm, no history of surgery to the lower extremity, and no history of pain or injury to the first MTPJ in the past 6 months. Interventions: PPP and MPP were evaluated under 4 areas of the foot: the rear foot, lateral forefoot, medial forefoot, and first MTPJ. Four pad conditions (no pad, metatarsal dome, U-shaped pad, and donut-shaped pad) were evaluated during slow running. All measurements were taken on a standardized treadmill using the Pedar in-shoe pressure-measurement system. Main Outcome Measures: PPP and MPP in 4 designated foot masks during slow running. Results: The metatarsal dome produced significant decreases in MPP (163.07 ± 49.46) and PPP (228.73 ± 63.41) when compared with no pad (P < .001). The U-shaped pad significantly decreased MPP (168.68 ± 50.26) when compared with no pad (P < .001). The donut-shaped pad increased PPP compared with no pad (P < .001). Conclusions: The metatarsal dome was most effective in reducing both peak and mean plantar pressure. Other factors such as pad comfort, type of activity, and material availability must also be considered. Further research should be conducted on the applicability to other foot types and symptomatic subjects. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
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11. Pressure Variation in Drip Laterals as Affected by Single and Double Inlet Systems and Sub Main Sizes
- Author
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Mohanty, B, Senapati, S C, Sahu, A P, and Panigrahi, B
- Published
- 2016
12. Mathematical modeling of co-current spontaneous imbibition in heterogeneous porous medium.
- Author
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Ghosh, Tufan, Raja Sekhar, G.P., and Deb, Debasis
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POROUS materials , *MATHEMATICAL models , *OIL field flooding , *CARBONATE reservoirs , *PETROLEUM , *NATURAL resources , *NATURAL gas - Abstract
Fractured carbonate reservoirs are principal crude oil and natural gas resources. These reservoirs are composed of matrix block with interconnected network of fractures. Oil or gas recovery from such low porous and low permeable reservoirs is important because a large amount of such hydrocarbon fluids are trapped inside those reservoir formulations. Water-flooding or more specifically spontaneous imbibition is one of the most effective recovery mechanisms to increase the production from fractured reservoirs. However, the performance of water-flooding mainly depends on the wettability of the reservoirs. In co-current imbibition, wetting phase displaces the non-wetting phase in such a way that the non-wetting phase moves in the same direction of the wetting phase. Hence the corresponding mathematical model requires a total flux condition. This study deals with the mathematical modeling of co-current spontaneous imbibition from heterogeneous porous reservoirs. The resulting governing equations are highly non-linear in nature. We solve these equations numerically and show that the co-current imbibition recovery is very much sensitive to the viscosity ratio, porosity variation models and the wettability of the reservoir. The impact of the viscosity ratio on the water saturation gradient and the end point mobility ratio is also analyzed. In addition, the variations in the heterogeneity and wettability of the medium and the corresponding influence on the sweeping efficiency of the co-current imbibition is investigated. • It is seen that a large viscosity ratio leads to less oil recovery. • The order of non-linearity of the heterogeneity shows counter-productive results. • Recovery is more sensitive to viscosity ratio, pore structure, and wettability. • Non-linear relative permeability functions reproduce field case results effectively. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
13. Pedobarography: a novel approach to test the efficacy of treatments for lameness; an experience with mavacoxib in dogs with elbow osteoarthritis.
- Author
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López, Sergio, Rodríguez, Oliver, Vilar, José M., Rubio, Mónica, Sopena, Joaquín J., Carrillo, José M., Santana, Angelo, and Rodríguez-Altonaga, José A.
- Subjects
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TREATMENT of leg abnormalities , *OSTEOARTHRITIS in dogs , *TREATMENT effectiveness , *POSTURAL balance ,ELBOW abnormalities - Abstract
Background: Pedobarographic analyses detect pressure redistribution among limbs and within limbs in humans, equids and dogs. The main objective of this study was to assess the usefulness of a set of pedobarographic parameters for the detection of lameness, as well as for its suitability for assessing the effects of therapies against osteoarthritis in dogs. With this purpose, eleven large-breed lame dogs with unilateral osteoarthritis due to elbow dysplasia were evaluated using a pressure platform prior to (D0) and after 3 months (D90) of treatment with mavacoxib, a COX-2 selective NSAID. The obtained parameters were: pressure distribution between lame and sound limbs, as well as paw area, mean pressure, and peak pressure of both lame and sound limbs. Results: The results showed statistical differences in all these parameters between lame and sound limbs at D0; however, at D90, differences were significantly decreased as result of the treatment, indicating a substantial functional recovery under the study design conditions. Conclusions: The provided data prove the suitability of this novel technique in canine models for the quantitative and objective assessment of lameness, but also for the evaluation of treatments for lameness caused by articular pain. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
14. BMI is a better indicator of cardiac risk factors, as against elevated blood pressure in apparently healthy female adolescents and young adult students: Results from a cross-sectional study in Tripura
- Author
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Surajit Debnath
- Subjects
Adolescent ,young adults ,female ,Tripura ,anthropometric measures ,BMI ,waist circumference ,waist to height ratio ,blood pressure indices ,DBP ,SBP ,pulse pressure ,mean pressure ,rate pressure product ,heart rate ,students ,Public aspects of medicine ,RA1-1270 - Abstract
Background: Anthropometric measures are used as indicators of elevated blood pressure, but reported to have variable sensitivity among populations. This study was undertaken to identify the better indicator of Cardiac-risk factors by statistical comparison of BMI, Waist circumference, and Waist to Height (WtHr) ratio in apparently healthy adolescents and young adult female students of Tripura. Materials and Methods: A cross-sectional study was conducted in a resource limited setup on 210 apparently healthy female adolescents and young adult students in Tripura. Mean (±SD) of all parameters were compared (ANOVA) to recognize significant independent (anthropometric measures) and dependent factors (blood pressure indices and so on). Correlation (r) analysis was used to identify the better (p) indicator of blood pressure indices (dependent variable) and its impact was assessed by Multiple Regression analysis. Results: blood pressure indices are comparatively higher in obese and overweight participants with statistically significant (95.5% confidence) mean differences. Significant correlation with dependent factors is observed with BMI followed by WtHr and Waist Circumference. Impact of anthropometric measures with blood pressure Indices is most significant for BMI (P ≤ 0.020) followed by WtHr (P ≤ 0.500) and waist circumference (P ≤ 0.520). Conclusion: BMI is a superior indicator of blood pressure indices and can identify participants at risk even in apparently healthy adolescent and young adult females.
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- 2016
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15. Head‐to‐head comparison of pressures during full cystometry, with clinical as well as in‐depth signal‐analysis, of air‐filled catheters versus the ICS‐standard water‐filled catheters
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Peter F.W.M. Rosier
- Subjects
Systematic difference ,Post hoc ,medicine.diagnostic_test ,business.industry ,Head to head ,Urology ,Mean pressure ,Cystometry ,Abdominal pressure ,Catheter ,medicine ,Urodynamic testing ,Neurology (clinical) ,Nuclear medicine ,business - Abstract
AIMS To compare in vivo differences of two catheter systems for urodynamics to further discover their measurement properties. METHODS Side-by-side catheterization with two catheters for intravesical and abdominal pressure during full cystometry in 36 prospectively recruited patients with analysis of mean and absolute differences at urodynamic events and post hoc in-depth signal analysis comparing the full pressure traces of both systems. RESULTS The mean pressure differences at urodynamic events between air-filled and water-filled systems are small, however, with a large variation, without a systematic difference. The majority of the intersystem differences are significantly larger than 5 cmH2 O. Further analysis showed that urodynamic event pressure differences of both systems at the start of the test were carried forward throughout the remainder of the test without subsequent or additional tendency to differ. Post hoc whole test signal analysis with pressures equalized from the first sample shows high cross-correlation (>0.981) between the pressure signals per location (rectum and bladder) per test and almost zero-time shift (
- Published
- 2021
16. Prediction of oscillatory heat transfer coefficient for a thermoacoustic heat exchanger through artificial neural network technique.
- Author
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A. Rahman, Anas and Zhang, Xiaoqing
- Subjects
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HEAT transfer coefficient , *THERMOACOUSTICS , *HEAT exchangers , *ARTIFICIAL neural networks , *NATURAL heat convection - Abstract
Heat exchangers under oscillatory flow condition in thermoacoustic devices are quite different with the traditional ones in heat transfer and flow behavior of thermo-viscous fluid. As a result, one cannot directly apply the heat transfer correlations for the steady flow to design thermoacoustic heat exchangers, otherwise, significant deviation will arise. However, some correlations of heat transfer for the oscillatory flow have not been well established yet. This study involves the application of artificial neural network (ANN) as a new approach to predict oscillatory heat transfer coefficient of one thermoacoustic heat exchanger under some operating conditions. One ANN model for the oscillatory heat exchanger used in one standing wave thermoacoustic refrigerator has been developed based on the published experimental data. This proposed ANN model has three layers with the configuration of 2-10-1, namely one input layer with two neurons representing two operating parameters, oscillating frequency and mean pressure, one hidden layer with optimal ten hidden neurons and one output layer with one neuron representing the oscillatory heat transfer coefficient as response. Moreover, a statistical analysis has been provided for studying the influence strength of these two input parameters on the oscillatory heat transfer coefficient. This ANN model had been proven to be desirable in accuracy for predicting oscillatory heat transfer coefficient by comparing ANN model results with both experimental results and calculated results by several other correlations from the published literature at the same operating conditions. This research work provides a new and accurate modeling approach based on ANN technique for the research of thermoacoustic heat exchangers and solving heat transfer problems related with oscillatory flow condition. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
17. Flexural Vibrations of a Plate under Changes in the Mean Pressure on Its Surfaces.
- Author
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Ilgamov, M. A.
- Subjects
- *
FLEXURAL vibrations (Mechanics) , *SURFACE pressure , *PRESSURE measurement , *BENDING strength , *DYNAMIC models , *PROBLEM solving - Abstract
Abstract—The influence of the mean excess pressure on a cylindrical static bend and vibrations of a plate is studied. Increasing and decreasing this pressure lead to a decrease and increase in deflection, respectively. In the first case, the plate shape stabilizes under the action of longitudinal forces, while in the second case, destabilization takes place. The critical value of the mean pressure is determined. The dynamic modes of plate deformation under a sharp increase and decrease in pressure are analyzed. In the first case, vibrations with increased frequency are excited, while in the second case, the excited vibrations have a reduced frequency compared to the natural frequency of the unloaded plate. For deep evacuation, an exponential increase in deflection with time is observed. A method for solving the problem for complex pressure changes has been developed. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
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18. 台阶式溢洪进水流压强特性试验研究.
- Author
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赵相航, 解宏伟, 郭馨, and 贺巨龙
- Abstract
In order to study the flow pressure characteristics of stepped spillway, combined with a reservoir in the Qinghai-Tibet plateau region, it used the physical model test method and studied the mean pressure, fluctuating pressure of stepped spillway on high altitude area. The results show that the mean pressure changing rule is consistent with fluctuating pressure on horizontal surface of stepped spillway. The pressure first falls down gradually from step's nook to step's lobe and then increases gradually. The mean pressure will be negative in the initial steps when the discharge is smaller. It appears negative pressure on steps more than half of vertical surface, fluctuating pressure intensity is larger on the steps apex angle. The mean pressure and fluctuating pressure intensity appear along alternating peaks and troughs, and present wavy development, as well as increase with the increase of discharge and the value changes when the step size is changed. Fluctuating pressure is time-varying stationary random procession stepped spillway. The dominant frequencies of fluctuations mainly concentrate in 0~2 Hz on stepped spillway, belonging to the low-frequency vibration and the probability density is skewness distribution and it will not endanger the safety of drainage buildings. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
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19. The Impact of Mean Arterial Pressure on Functional Outcome Post Trauma-Related Acute Spinal Cord Injury: A Scoping Systematic Review of the Human Literature.
- Author
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Sabit, Behzad, Zeiler, Frederick Adam, and Berrington, Neil
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ARTERIAL physiology , *BLOOD pressure , *INFORMATION storage & retrieval systems , *MEDICAL databases , *MEDICAL information storage & retrieval systems , *LIFE skills , *MEDLINE , *SPINAL cord injuries , *WOUNDS & injuries , *SYSTEMATIC reviews , *LITERATURE reviews - Abstract
Purpose: To perform a scoping systematic review on the literature surrounding mean arterial pressure (MAP) and functional outcomes post traumatic acute spinal cord injury (ASCI). Methods: We performed a systematic review of the literature via searching MEDLINE, BIOSIS, EMBASE, Global Health, SCOPUS, and Cochrane Library from inception to January 2015. We also performed a handsearch of various published meeting proceedings. Through a 2-step review process, employing 2 independent reviewers, we selected articles for the final review based on predefined inclusion/exclusion criteria. Results: Nine studies were included in the final review. Only 2 were prospective studies. All studies documented some degree of objective functional outcome in relation to MAP posttraumatic ASCI. Four studies documented a relation between higher MAP and improved functional outcome. Five studies failed to show any relationship between MAP and functional outcome. Conclusions: Although no definitive conclusions could be reached based on the data collected, this study does give valuable insight into future avenues of research on the topic of hemodynamic management in traumatic ASCI as well as provides guidelines for refinement of future study design. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
20. Prediction of Cooling Load for a Standing Wave Thermoacoustic Refrigerator through Artificial Neural Network Technique.
- Author
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Rahman, Anas A. and Zhang, Xiaoqing
- Abstract
This study involves the application of artificial neural network (ANN) as a new approach to predict cooling load of thermoacoustic refrigerator under some operating conditions. One ANN model for a standing wave thermoacoustic refrigerator had been developed based on the experimental data from other literature. Cooling load was chosen as a response to input parameters, mean pressure and frequency in ANN model. A multi-layer feed-forward network with a back propagation algorithm had been proposed for predicting cooling load of the thermoacoustic refrigerator. This proposed ANN model has three layers with the configuration of 2-10-1, namely, input layer with two neurons representing the two operating parameters, one hidden layer with an optimal 10 hidden neurons, and output layer with one neuron representing the cooling load. The ANN model had been proven to be desirable in accuracy for predicting the cooling load by comparing model results with experimental results in literature work. This research work would provide a new modelling approach based on ANN technique for solving complex thermoacoustic problems with linear or nonlinear nature. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
21. DIFFERENCES IN PLANTAR PRESSURE BETWEEN THE DIABETIC AND HEALTHY SUBJECTS.
- Author
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LIU, Rongtian, HU, Mingyu, GU, Yiming, LIN, Hong, XU, Bo, XU, Jiuping, and ZHOU, Jin
- Subjects
- *
DIABETIC foot , *PEOPLE with diabetes , *PRESSURE , *PRESSURE measurement , *FOOT - Abstract
Since varied thresholds were reported in the literature and in what range of peak pressure is safe was not answered, the aim of this study was to compare the plantar pressure between the diabetic and healthy subjects and then to find the risk threshold of pressure for diabetic patients. 177 volunteers (83 diabetic patients and 94 control ones) were recruited and their plantar pressure were measured by the Emed pressure system. Plantar region was divided into seven regions: big toe, MTH1-5 and MF, under which mean pressure (kPa) was calculated. The results show that major variations existed and mean pressure of the patients was 2.5% lower than that of healthy counterparts; however, the law of differences between the diabetic patients and healthy ones in 3%, 50% and 96% percentile level could not be found. Overall, attention should be paid to changes in feet of diabetic patients, who must receive appropriate treatment when their mean pressure exceeds 100kPa (about 10N/cm2). [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
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22. Aortic Stenosis Progression, Cardiac Damage, and Survival
- Author
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Hector I. Michelena, Amber Boler, Li Tan Yang, Christopher G. Scott, Matthew J. Maurer, Jose R. Medina-Inojosa, Christophe Tribouilloy, Maurice Enriquez-Sarano, and Mackram F. Eleid
- Subjects
Aortic valve ,medicine.medical_specialty ,business.industry ,Incidence (epidemiology) ,Mean pressure ,030204 cardiovascular system & hematology ,medicine.disease ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,Stenosis ,0302 clinical medicine ,medicine.anatomical_structure ,Bicuspid aortic valve ,Interquartile range ,Internal medicine ,Cohort ,cardiovascular system ,Cardiology ,Medicine ,Radiology, Nuclear Medicine and imaging ,Cardiac skeleton ,Cardiology and Cardiovascular Medicine ,business - Abstract
Objectives This study sought to compare aortic stenosis (AS) progression rates, AS-related cardiac damage (AS-CD) indicator incidence and determinants, and survival between patients with tricuspid aortic valve (TAV)-AS and those with bicuspid aortic valve (BAV)-AS. Background Differences in AS progression and AS-CD between patients with BAV and patients with TAV are unknown. Methods We retrospectively studied consecutive patients with baseline peak aortic valve velocity (peakV) ≥2.5 m/s and left ventricular ejection fraction ≥50%. Follow-up echocardiograms (n = 4,818) provided multiparametric AS progression rates and AS-CD. Results The study included 330 BAV (age 54 ± 14 years) and 581 patients with TAV (age 72 ± 11 years). At last echocardiogram (median: 5.9 years; interquartile range: 3.9 to 8.5 years), BAV-AS exhibited similar peakV and mean pressure gradient (MPG) as TAV-AS, but larger calculated aortic valve area due to larger aortic annulus (p Conclusions In this cohort, TAV-AS and BAV-AS progression rates were similar. Rapid progression did not affect survival and was determined by cardiac risk factors for BAV-AS (particularly in patients with BAV
- Published
- 2021
23. A comparison of two designs of postoperative shoe for hallux valgus surgery: A biomechanical study in a cadaveric model
- Author
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Ester Navarro-Cano, Ana Carrera, Francisco Reina, Gustavo Lucar-López, and Kerbi Alejandro Guevara-Noriega
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Male ,musculoskeletal diseases ,medicine.medical_specialty ,Heel ,Mean pressure ,Barefoot ,03 medical and health sciences ,Fixation (surgical) ,0302 clinical medicine ,Cadaver ,otorhinolaryngologic diseases ,medicine ,Humans ,Orthopedics and Sports Medicine ,Postoperative Period ,Hallux Valgus ,Metatarsal Bones ,Aged ,Aged, 80 and over ,030222 orthopedics ,biology ,business.industry ,technology, industry, and agriculture ,030229 sport sciences ,Middle Aged ,biology.organism_classification ,Biomechanical Phenomena ,Shoes ,Surgery ,body regions ,Valgus ,medicine.anatomical_structure ,Orthopedic surgery ,Female ,Cadaveric spasm ,business ,Foot (unit) - Abstract
Hallux Valgus Surgery success depends not only on the operative technique, but also on the care of the foot during the postoperative period. Orthopedic shoes have been developed to decrease the weight load on the first ray, an excess of which might lead to a loss of fixation or pseudoarthrosis. The goal of this study was to determine how the load distribution changed as the forced applied to the foot increased, with and without an orthopedic shoe. Also, we compared to different shoe models.Pressure sensors were placed under the first metatarsal head and the heel of twenty specimens of fresh cadaveric adult feet. Two orthopedic shoes were chosen, a double padded (MS) and a reverse camber shoe (RCS). 10 kg loads were progressively applied, up to 60 kg. We first compared three instances: no shoe, MS and RCS. A secondary analysis comparing barefoot versus shoes was performed. A mean comparison was performed (ANOVA/T-student).The mean pressure of the heed and the first metatarsal showed that there were significant differences between groups (P.005). The secondary analysis (no shoe vs orthopedic shoes) showed that the pressure without shoe was significantly higher than with any orthopedic shoe (P.005). There were no statistically significant differences between models of shoes (P = .402).After a surgical procedure for hallux valgus fixation, postoperative shoes should be indicated to decrease the pressure on the first metatarsal head and heel in order to avoid an overload of the postoperative area.Cadaveric study. Level V.
- Published
- 2021
24. Optimal pressure in obstructive sleep apnea: auto-titrating positive airway pressure versus predictive equations
- Author
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Iman Galal and Haytham S. Diab
- Subjects
medicine.medical_specialty ,Percentile ,Statistical difference ,Mean pressure ,Polysomnography ,predicted pressure ,Diseases of the respiratory system ,Mathematical equations ,polysomnography ,Internal medicine ,Positive airway pressure ,medicine ,positive airway pressure ,obstructive sleep apnea ,General Environmental Science ,Titration Study ,medicine.diagnostic_test ,RC705-779 ,business.industry ,General Engineering ,medicine.disease ,Obstructive sleep apnea ,Cardiology ,General Earth and Planetary Sciences ,business ,auto-titrating positive airway pressure - Abstract
Background The prescription of equation-based predicted pressure (Ppred) using mathematical equations has been proposed as a practical strategy for the determination of effective positive airway pressure (PAP). This study aimed at comparing the differences between therapeutic pressures obtained by auto-titrating positive airway pressure (APAP) and 10 predictive mathematical equations among Egyptian patients with obstructive sleep apnea (OSA). Patients and methods A retrospective cross-sectional study included 25 PAP-naive patients (23 males and two females) with polysomnographically confirmed OSA. The 95th percentile pressure (P95) of an APAP device during an attended successful titration study was selected as the effective reference PAP, against which PPred calculated from ten predictive equations was compared. Results Among the 25 patients included, four patients had mild, eight had moderate, whereas the remaining 13 patients had severe OSA. The mean P95 was higher than all predictive equations. A total of 24 (96%) of the 25 included patients experienced acceptable air leak during APAP titration. P95 correlated significantly and positively with pressures calculated by most of predictive equations except for those of equations 2, 6, and 7. Comparison between P95 and Ppred showed nonsignificant statistical difference for pressure calculated by Series equation, whereas Ppred of other equations were significantly lower than P95. Mean pressure difference between P95 and Ppred was around three in most of the equations with Series equation carrying the least mean pressure difference (0.7 cmH2O). Conclusion P95 is higher than Ppred, yet Series equation was the closest to P95. The utility of predictive equations for determining effective PAP level can serve a beneficial role during titration studies and can be used with caution as a practical alternative for PAP titration.
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- 2021
25. Comparison of CFD-DEM and TFM approaches for the simulation of the small scale challenge problem 1
- Author
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Musango Lungu, Lloyd Mukosha, and John Siame
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Physics ,General Chemical Engineering ,Drop (liquid) ,Bubble ,Mean pressure ,02 engineering and technology ,Mechanics ,021001 nanoscience & nanotechnology ,Physics::Fluid Dynamics ,020401 chemical engineering ,Drag ,Fluidized bed ,Slugging ,Particle velocity ,0204 chemical engineering ,0210 nano-technology ,CFD-DEM - Abstract
The open source code MFIX is used to perform CFD-DEM and TFM simulations based on the small scale challenge problem 1 fluidized bed set up. The basic flow features such as the core-annulus structure and slugging dynamics are well predicted by both modeling approaches. Similarly the first four statistical moments of the particle velocity distributions from HsPIV measurements are equally reproduced qualitatively by the models. The predicted mean pressure drop is independent of the drag correlation used in both modeling frameworks but the CFD-DEM model gives predictions closer to the experimental values. Predicted fluctuating quantities such as rms and granular temperature show sensitivity to the drag model used. The TFM demonstrates greater accuracy over the CFD-DEM in prediction of the particle granular temperature while the opposite is true for the bubble granular temperature. CFD-DEM simulations on average take twice the time required to perform a TFM simulation.
- Published
- 2021
26. IMMEDIATE RESULTS OF PERCUTANEOUS TRANS-MITRAL COMMISSOROTOMY IN JUVENILE MITRAL STENOSIS
- Author
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Fakher e Fayaz, Muhammad Younas, Mubashar Shervani, Ahsan Beg, and Amjad Mahmood
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medicine.medical_specialty ,Medicine (General) ,Percutaneous ,juvenile mitral stenosis ,Rheumatic mitral stenosis ,Mean pressure ,Balloon ,R5-920 ,Mitral valve ,Internal medicine ,medicine ,Juvenile ,cardiovascular diseases ,business.industry ,ptmc ,Retrospective cohort study ,rheumatic heart disease ,medicine.disease ,acute rheumatic fever ,Stenosis ,medicine.anatomical_structure ,Cardiology ,cardiovascular system ,percutaneous trans mitral commissorotomy ,Medicine ,business - Abstract
Objectives: Immediate result of PTMC in juvenile (5-12 years) rheumatic mitral stenosis. Study Design: Observational descriptive and retrospective study. Place and Duration of Study: Institute of Cardiology, Multan from 2009 to Jun 2020. Methodology: This is an observational descriptive and retrospective study carried out at Institute of Cardiology, Multan from 2009 to Jun 2020. Patients with clinical evidence of significant mitral stenosis were undergone transthoracic echocardiography. Mitral stenosis was defined as mitral valve area 8 were also excluded from the study. Variables recorded on a performa were age, weight, left atrial size, mean mitral valve gradient, preprocedure MR. Reduction of mitral valve mean pressure gradients to less than
- Published
- 2020
27. Benefits of robotically-assisted surgery for complex mitral valve repair
- Author
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Naonori Kawamoto, Shin Yajima, Soichiro Kitamura, Takashi Kakuta, Satsuki Fukushima, Junjiro Kobayashi, Naoki Tadokoro, Yusuke Shimahara, and Tomoyuki Fujita
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Adult ,Male ,Pulmonary and Respiratory Medicine ,medicine.medical_specialty ,medicine.medical_treatment ,Mean pressure ,Robotic Surgical Procedures ,Mitral valve ,medicine ,Minimally invasive cardiac surgery ,Humans ,Minimally Invasive Surgical Procedures ,Robotic surgery ,Thoracotomy ,Cardiac Surgical Procedures ,Aged ,Heart Valve Prosthesis Implantation ,Mitral valve repair ,Mitral regurgitation ,Adult Cardiac ,business.industry ,Mitral Valve Insufficiency ,Middle Aged ,Surgery ,Treatment Outcome ,medicine.anatomical_structure ,Concomitant ,Mitral Valve ,Female ,Tricuspid Valve ,Cardiology and Cardiovascular Medicine ,business ,Follow-Up Studies - Abstract
OBJECTIVES To determine whether robotic mitral valve repair can be applied to more complex lesions compared with minimally invasive direct mitral valve repair through a right thoracotomy. METHODS We enrolled 335 patients over a 9-year period; 95% of the robotic surgeries were performed after experience performing direct mitral valve repair. RESULTS The mean age in the robotic versus thoracotomy repair groups was 61 ± 14 vs 55 ± 11 years, respectively (P CONCLUSIONS Robotic surgery can be applied to repair more complex mitral lesions, with excellent early outcomes.
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- 2020
28. Analysis of Correlation between Heart Rate and Pulse Wave Velocity using Cardiovascular Simulator
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Dong-Eun Kim, Min Jang, Min-Woo Lee, Jung-Hoon Lee, and Sang-Hoon Shin
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010302 applied physics ,business.industry ,Mean pressure ,General Physics and Astronomy ,02 engineering and technology ,Stroke volume ,021001 nanoscience & nanotechnology ,01 natural sciences ,Arterial tree ,Correlation ,Pressure waveform ,0103 physical sciences ,Heart rate ,cardiovascular system ,Medicine ,cardiovascular diseases ,0210 nano-technology ,business ,Pulse wave velocity ,Simulation - Abstract
In clinical studies, the effect of heart rate (HR) alone as feedback for maintaining homeostasis cannot be observed. Therefore, in this study, the effect of HR on pulse wave velocity (PWV) was investigated using a simulator without feedback. This was achieved via a one-tube model that simplifies the human arterial system and an arterial tree model similar to the human body, using a cardiovascular simulator. The one-tube model measured the pressure waveform at two measuring points 1.2 m apart, while the arterial tree model measured the pressure waveform in the carotid and femoral arteries. In the one-tube experiment, the effects of HR, mean pressure (MP), and stroke volume (SV) on PWV were independently investigated. PWV was found to increase as HR increased, but was not affected when MP and SV were changed. Further, in the arterial tree model experiment, it was observed that the PWV increased with an increase in HR. The results of this study showed that even in a simulator containing a human arterial model made of silicone material with no human feedback action, changes in HR alone affect the PWV.
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- 2020
29. Left atrial structural and functional remodeling following balloon mitral valvuloplasty
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Ahmed E. Hassan, Mohamed Eid Fawzy, Karim Said, Mohamed Hassan, Wafaa El Aroussy, Amir Anwar Samaan, and Magdi H. Yacoub
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Adult ,Balloon Valvuloplasty ,Male ,medicine.medical_specialty ,Time Factors ,Mitral valvuloplasty ,Mean pressure ,030204 cardiovascular system & hematology ,Balloon ,Severity of Illness Index ,Young Adult ,03 medical and health sciences ,0302 clinical medicine ,Left atrial ,Internal medicine ,Humans ,Mitral Valve Stenosis ,Medicine ,Radiology, Nuclear Medicine and imaging ,In patient ,Prospective Studies ,030212 general & internal medicine ,Body surface area ,business.industry ,Rheumatic Heart Disease ,Atrial Remodeling ,Recovery of Function ,medicine.disease ,Stenosis ,Treatment Outcome ,Echocardiography ,Left Atrial Functions ,Cardiology ,Mitral Valve ,Atrial Function, Left ,Female ,Cardiology and Cardiovascular Medicine ,business - Abstract
Mitral stenosis (MS) is associated with left atrial (LA) functional and morphological changes as a result of chronic increase in LA pressure. Relieving the mitral obstruction via balloon mitral valvuloplasty (BMV) might be associated with LA structural and functional remodeling. To study alterations of LA volume and functions 1 year following successful BMV in patients with isolated rheumatic severe mitral stenosis. Thirty patients (median age 33 years, 22 women) with severe rheumatic MS were included in the study. Using biplane method, trans-thoracic 2D echocardiography was used to estimate LA volume indexed to body surface area (BSA). Maximal, minimal and pre-A left atrial volumes were measured and indexed to BSA. LA volumetric functions were then assessed and the measurements were repeated 6 months and 1 year after successful valvuloplasty. At baseline, median mitral valve area (MVA) was 0.9 (0.6–1.3) cm2 measured by planimetry with a mean pressure gradient of 12.5 (8–24) mmHg. Following BMV, a significant regression of left atrial volume index was noticed at 6 months compared to baseline (51 vs. 60 ml/m2, p = 0.001) with a further decrease at 1 year (48 vs. 51 ml/m2, p = 0.03). At 6 months, volumetric assessment of left atrial functions showed a significant improvement in LA total emptying fraction (42% vs 30%, p = 0.001) as well as in LA passive emptying fraction (26% vs 14%, p = 0.033) and LA active emptying fraction (20% vs. 18%, p = 0.016). All these indices showed further improvement at 1 year [47% (P = 0.02), 29% (p = 0.03) and 31% (p = 0.001) respectively]. In patients with isolated rheumatic MS, mitral valvuloplasty was associated with a significant decline of LA volume accompanied by a significant improvement of its volumetric functions.
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- 2020
30. Influence of Outer Parts of a Strip on the Deformation and Force Parameters of Thin-Sheet Rolling
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R. L. Shatalov and M. A. Kulikov
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Materials science ,0211 other engineering and technologies ,Mean pressure ,02 engineering and technology ,STRIPS ,Deformation (meteorology) ,law.invention ,Physics::Fluid Dynamics ,Brass ,law ,Metallic materials ,Materials Chemistry ,medicine ,Composite material ,021102 mining & metallurgy ,020502 materials ,Metals and Alloys ,Stiffness ,Thin sheet ,Physics::Classical Physics ,Condensed Matter Physics ,0205 materials engineering ,Mechanics of Materials ,visual_art ,visual_art.visual_art_medium ,medicine.symptom - Abstract
We present the results of experimental investigations of the distribution of deformation indicators and rolling forces along the length of brass (L63) strips in a 150 × 235 two-roll mill equipped with a microcontroller system for high-precision measurements of loads acting upon the rolls. The results of the quantitative analyses of changes in the sizes of strips and rolling forces on stationary and nonstationary sections along the strip length are presented. A significant effect of the outer parts of the strip on the rolling force and the pressure of the metal upon the rolls is established. On the basis of the experimental results, we propose an equation for the evaluation of the influence of the outer parts of the strip on the rolling force and pressure. The equation for the mean pressure of the metal upon the rolls is improved with regard for the influence of the outer parts and the stiffness of the strip on the site of deformation in the process of thin-sheet rolling. It is shown that the proposed equations make it possible to increase the accuracy of evaluation of pressure and determination of rolling forces along the length of thin strips.
- Published
- 2020
31. The Impact of Mean Arterial Pressure on Functional Outcome Post-Acute Spinal Cord Injury: A Scoping Systematic Review of Animal Models.
- Author
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Sabit, Behzad, Zeiler, Frederick A., and Berrington, Neil
- Subjects
- *
SPINAL cord injuries , *HYPOTENSION , *HEALTH outcome assessment , *MEDLINE , *ANIMAL models in research - Abstract
The aim of this work was to perform a scoping systematic review on the animal literature surrounding mean arterial blood pressure (MAP) and functional outcomes post-acute spinal cord injury (ASCI). We performed a systematic review of the literature by searching: MEDLINE, BIOSIS, EMBASE, Global Health, SCOPUS, and Cochrane Library from inception to January 2015. We also performed a hand search of various published meeting proceedings. Through a two-step review process, using two independent reviewers, we selected articles for the final review based on pre-defined inclusion/exclusion criteria. Ten studies were included within the final systematic review. A variety of animal models were used within these studies. All included studies had some objective means of documenting functional outcome post-manipulation of the MAP. Four studies could be considered to be 'positive studies,' showing some neurological improvement or beneficial effect to having the blood pressure manipulated. Two studies displayed worse functional outcomes secondary to episodes of hypotension. Four studies failed to demonstrate a relationship between MAP and functional outcome within the animal models. This review concludes that, within the animal literature, there is insufficient evidence to draw a conclusion about the effect of MAP on neurological outcome in animal models of ASCI. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
32. Does Quicker Mean Better? Comparison of Rapid Deployment Versus Conventional Aortic Valve Replacement
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Yi Lu, Jianfang Wang, Zexin Chen, Jia Wei, Fei Li, and Zhejun Cai
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medicine.medical_specialty ,Blood transfusion ,business.industry ,medicine.medical_treatment ,Mean pressure ,Atrial fibrillation ,General Medicine ,030204 cardiovascular system & hematology ,medicine.disease ,Confidence interval ,law.invention ,03 medical and health sciences ,0302 clinical medicine ,Aortic valve replacement ,Randomized controlled trial ,law ,Internal medicine ,Relative risk ,medicine ,Cardiology ,Cardiopulmonary bypass ,030212 general & internal medicine ,Cardiology and Cardiovascular Medicine ,business - Abstract
The aim of this meta-analysis was to compare the clinical outcomes in patients who underwent rapid deployment aortic valve replacement (RDAVR) and conventional bio prosthetic aortic valve replacement (CAVR).We performed a literature search by August 2018. The primary outcomes were hospital and 1-year mortality, and the secondary endpoints included the aortic cross-clamp (ACC), cardiopulmonary bypass (CPB) time, and postoperative and valve-related complications.Two randomized controlled trials and 13 propensity score-matched studies were included. There was no difference between RDAVR and CAVR in hospital mortality (2.5% versus 2.1%; risk ratio (RR) 1.16 [95% confidence interval (CI) 0.80-1.68]) or 1-year mortality (2.9% versus 4.1%; RR 0.69 [95% CI 0.34-1.34]). RDAVR significantly reduced the ACC time ( (mean difference (MD) -24.33 [95% CI -28.35 to -20.32]) and CPB time (MD -21.51 [95% CI -22.83 to -20.20]). The pooled analysis showed that RDAVR doubled the occurrence of permanent pacemaker implantation (8.6% versus 4.3%; RR 2.05 [95% CI 1.62-2.60]). Meanwhile, the blood transfusion amount (MD -1.54 [95% CI -2.22 to -0.86]) and postoperative atrial fibrillation (POAF) occurrence (RR 0.83 [95% CI 0.69-0.99]) was reduced. The difference of paravalvular leakage frequency between RDAVR and CAVR was marginal (RR 1.77 [95% CI 1.00-3.17]; P = 0.05). Furthermore, RDAVR was related to larger valves (MD 0.70 cm [95% CI 0.33-1.07]) and lower mean pressure gradients (MD -1.93 mmHg [95% CI -3.58 to -0.28]).The hospital and 1-year survival rates between RDAVR and CAVR are comparable. RDAVR reduces POAF occurrence and blood transfusion but is associated with a higher occurrence of pacemaker implantation.
- Published
- 2020
33. Heat release effects on the Reynolds stress budgets in turbulent premixed jet flames at low and high Karlovitz numbers
- Author
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Jinyoung Lee, Jonathan F. MacArt, and Michael E. Mueller
- Subjects
Physics ,010304 chemical physics ,Turbulence ,General Chemical Engineering ,Isotropy ,Mean pressure ,Direct numerical simulation ,General Physics and Astronomy ,Energy Engineering and Power Technology ,02 engineering and technology ,General Chemistry ,Mechanics ,Reynolds stress ,Combustion ,01 natural sciences ,Thermal expansion ,Physics::Fluid Dynamics ,Fuel Technology ,020401 chemical engineering ,0103 physical sciences ,Turbulence kinetic energy ,0204 chemical engineering - Abstract
In turbulent premixed flames at low Karlovitz number, combustion heat release can have a significant impact on turbulence. Thermal expansion in flame induces dilatation, and the corresponding pressure–dilatation correlation acts as a primary source of turbulent kinetic energy (TKE). As a consequence, the flame-normal component of the normal Reynolds stresses significantly increases. Additionally, for sheared flames, typical of jet flames, the shear component of the Reynolds stresses exhibits counter-Boussinesq behavior. For flames at low Karlovitz number, where these effects dominate, no models have successfully predicted all Reynolds stress components. To develop more complete turbulence models, heat release effects on the evolution of all Reynolds stress components need to be analyzed. In this work, Reynolds stress budgets are evaluated from Direct Numerical Simulation (DNS) databases of spatially-evolving turbulent premixed planar jet flames at low and high Karlovitz numbers. In the Reynolds stress budgets, the velocity–pressure gradient correlation term is important at both Karlovitz numbers but serves fundamentally different roles in each case. In the budgets for the normal components, the velocity–pressure gradient correlation term is decomposed into a redistribution term and an isotropic term, where the redistribution term acts to redistribute energy between the Reynolds stress components and the isotropic term is the pressure–dilatation source term of turbulent kinetic energy. At high Karlovitz number, the isotropic term is negligible, and the redistribution term acts to isotropize the turbulence as in non-reacting flows. Conversely, at low Karlovitz number, the isotropic term acts as a large source, and the redistribution term preferentially injects energy into the flame-normal component at the expense of other components which acts to make the turbulence less isotropic. In the budget for the shear component, the shear production term dominates the velocity–pressure gradient correlation term at high Karlovitz number, but the opposite is observed at low Karlovitz number. The dominance of the velocity–pressure gradient correlation term at low Karlovitz number is primarily induced by the flame-generated mean pressure gradient and ultimately leads to the counter-Boussinesq behavior of the shear component. The overall analysis indicates that any turbulence model that relies on small-scale isotropy and/or rapid isotropization will fail to capture the heat release effects on turbulence at low Karlovitz number.
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- 2020
34. In vitro comparison of everting vs. non-everting suture techniques for the implantation of a supra-annular biological heart valve
- Author
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Roza Meyer-Saraei, Rüdiger Lange, Andrea Münsterer, Anatol Prinzing, Zachary A Sexton, Michael Scharfschwerdt, and Nazan Puluca
- Subjects
Pulmonary and Respiratory Medicine ,Aortic valve ,business.industry ,medicine.medical_treatment ,Pulsatile flow ,Mean pressure ,Hemodynamics ,030204 cardiovascular system & hematology ,medicine.disease ,ddc ,Closing Volume ,03 medical and health sciences ,0302 clinical medicine ,medicine.anatomical_structure ,030228 respiratory system ,Aortic valve replacement ,Valve replacement ,medicine ,Original Article ,Heart valve ,business ,Nuclear medicine - Abstract
Background The aim of this study was to evaluate the hemodynamic effect of different suturing techniques for aortic valve replacement (AVR) in vitro. Whether or not the applied suturing technique impacts the outflow tract diameter by narrowing the annulus diameter was examined. Methods The commonly applied non-everting pledget forced suture technique (NE, n=13) was compared with an everting pledget forced suture (ET, n=13) for AVR using the 25 mm St. Jude Trifecta aortic valve. Hemodynamic parameters were obtained in a pulsatile flow simulator. A high speed camera captured the visual aspects of the suturing technique. Results Despite some kind of left ventricular outflow narrowing due to protruding pledgets using the NE suture technique, mean pressure gradients of both techniques were nearly similar (NE 5.88±2.7 mmHg, ET 5.23±1.31 mmHg, P=0.44). Closing volume (NE 3.16±0.48 mL; ET 3.51±0.68 mL; P=0.14) and the leakage volume (NE: 8.09±2.53 mL; ET: 8.35±3.65 mL; P=0.83) also showed no differences. Conclusions AVR using either suturing techniques leads to a similar hemodynamic performance in vitro. The impact of the suturing technique may be higher in a smaller annulus. Therefore, further studies using smaller prostheses are necessary.
- Published
- 2020
35. The effect of match fatigue in elite badminton players using plantar pressure measurements and the implications to injury mechanisms
- Author
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Raúl Valldecabres, Ana-Maria de Benito, and Jim Richards
- Subjects
medicine.medical_specialty ,0206 medical engineering ,Mean pressure ,Physical Therapy, Sports Therapy and Rehabilitation ,02 engineering and technology ,03 medical and health sciences ,0302 clinical medicine ,Physical medicine and rehabilitation ,medicine ,Humans ,Injury mechanisms ,Injury risk ,Orthopedics and Sports Medicine ,Foot pressure ,Fatigue ,Foot ,business.industry ,Plantar pressure ,Biomechanics ,Racquet Sports ,C640 ,030229 sport sciences ,020601 biomedical engineering ,Biomechanical Phenomena ,Shoes ,body regions ,Calcaneus ,business ,Foot (unit) - Abstract
The purpose of this study was to investigate the differences in plantar pressure under the lead and trail foot between two lunge tasks to the net in the dominant (LD) and non-dominant (LND) directions, and to explore how fatigue affects the plantar pressure patterns whilst performing movements before and after a competitive match. Peak and mean pressure were measured with the Biofoot-IBV in-shoe system from five repetitions of each task, with sensors positioned under the calcaneus, midfoot and phalanges on the lead and trail foot. Data were collected pre and immediately post-playing an official first national league competition match. The study was conducted with a sample of thirteen first league badminton players. A 2 × 2 repeated ANOVA found significant differences between the two tasks and between pre- and post-match (fatigued state). Players also had different foot pressure distributions for the LD and LND tasks, which indicated a difference in loading strategy. In a fatigued state, the plantar pressure shifted to the medial aspect of the midfoot in the trail limb, indicating a reduction in control and a higher injury risk during non-dominant lunge tasks.
- Published
- 2020
36. The effect of mean pressure on the performance of a single-stage heat-driven thermoacoustic cooler
- Author
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Irna Farikhah
- Subjects
010302 applied physics ,Materials science ,Single stage ,0103 physical sciences ,Architecture ,Mean pressure ,02 engineering and technology ,Mechanics ,021001 nanoscience & nanotechnology ,0210 nano-technology ,01 natural sciences ,General Environmental Science ,Civil and Structural Engineering - Abstract
Waste heat is an environmental issue in the world. There are some technologies that can be used to recovery the waste heat, one of which is thermoacoustic cooler technology. Thermoacoustic technology can be divided into two parts: one is thermoacoustic engine and cooler. To design the cooler system having high efficiency and lower onset heating temperature, the effect of mean pressure is investigated. By increasing mean pressure from 0.5 to 3 MPa, the heating temperature generating acoustic power can be decreased from 831 to 580 K. Moreover, 15% of Thermodynamic upper limit value of the whole cooler system is achieved.
- Published
- 2020
37. Evaluation of Cavitation Occurrence Based on Reliability in Chute Spillways by Using First Order Reliable Method and Monte Carlo Simulation Method from 18 Spillways Laboratory Models, Iran
- Author
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Amin Hasanalipour Shahrabadi and Mehdi Azhdary Moghaddam
- Subjects
Spillway ,Cavitation ,Flow (psychology) ,Monte Carlo method ,Mean pressure ,Environmental science ,Probabilistic design ,First order ,Reliability (statistics) ,Civil and Structural Engineering ,Marine engineering - Abstract
Controlling cavitation occurrence is one of the most important factors in chute spillways designing due to high velocity and the negative pressure of flow. A probabilistic design approach was implemented in the present study to estimate the probability of cavitation occurrence on chute spillways. In addition, the uncertainty presence of the effective parameters in the limit state function related to the cavitation occurrence was highlighted in the present design. The probability of cavitation occurrence was studied based on the reliability of first order reliable method (FORM) and it was controlled by Monte Carlo simulation method. The data was extracted from eighteen spillways laboratory models built by the Iranian Water Research Institute, among which ten were aerated and eight were without aerator. Accordingly, as a result of the performance of these spillways and the cavitation occurrence in the prototype, a graph and its relationship was found for controlling the cavitation occurrence and its failure probability based on the mean velocity and flow mean pressure along the chute spillway. According to the results of this study as a new method for designing based on reliability, it could be controlled the probability of cavitation occurrence.
- Published
- 2020
38. Bench Validation of a Handcrafted Prototype Catheter for Intra-gastric Pressure Monitoring
- Author
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Daniela Burbano, Jose Luis Aldana, Julián Chica Yantén, García A, Camilo Jose Salazar, Alvaro I. Sánchez, and Jorge Humberto Mejía
- Subjects
medicine.medical_specialty ,Catheters ,Abdominal compartment syndrome ,Manometry ,Bench model ,Mean pressure ,03 medical and health sciences ,0302 clinical medicine ,Abdomen ,Pressure ,medicine ,Humans ,In patient ,Monitoring, Physiologic ,business.industry ,Gold standard (test) ,medicine.disease ,Gastric pressure ,Catheter ,030220 oncology & carcinogenesis ,030211 gastroenterology & hepatology ,Surgery ,Radiology ,Intra-Abdominal Hypertension ,business ,Abdominal surgery - Abstract
Abdominal compartment syndrome is a sustained intra-abdominal pressure (IAP) >20 mm Hg associated with new organ dysfunction. In order to prevent its development and related complications, IAP monitoring should be performed in patients with risk factors. Although techniques for its monitoring have been developed, they are of high cost and not always available in low- and lower–middle-income countries. Therefore, we aim to develop and validate in a bench model a handcrafted catheter to be used as an alternative method to measure the intra-gastric pressure (IGP) as a surrogate of the IAP. We used an acrylic water container as a model of the abdomen and four handcrafted catheters made of a 16 Fr Levin tube with a globe finger tied with silk in the distal end, inflated with 1 cm of air. They were placed on the bottom of the container where the water pressure was directly measured as a gold standard. The agreement between the two measures was assessed with the Bland–Altman method. We performed 120 simultaneous measures. The mean pressure difference was 0.218 (95% CI 0.074 to 0.363). The handcrafted prototype catheter and the direct measure were highly correlated. The new catheter is a reliable and reproducible tool for pressure monitoring. However, before it can be used in the clinical setting for IAP monitoring, validation in human models in a real clinical setting needs to be performed.
- Published
- 2020
39. The effects of fatigue on plantar pressure and balance in adolescent volleyball players with and without history of unilateral ankle injury
- Author
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Mehrdad Anbarian and A. Farzami
- Subjects
medicine.medical_specialty ,business.industry ,Plantar pressure ,Significant difference ,Mean pressure ,030209 endocrinology & metabolism ,030229 sport sciences ,medicine.disease_cause ,03 medical and health sciences ,0302 clinical medicine ,Ankle injury ,Jumping ,Physical medicine and rehabilitation ,medicine ,Orthopedics and Sports Medicine ,Foot pressure ,business ,human activities ,Foot (unit) ,Balance (ability) - Abstract
Summary The purpose of this study was to assess plantar pressure and static balance alterations after jumping and landing. According to the importance of devastating impact of improper distribution of plantar forces on the incidence of abnormal movements and stresses in the foot structure of volleyball players, studying the effect of fatigue on plantar pressure and static balance can lead to significant achievements in the evaluation of this organ's performance. In this study, 12 male adolescent volleyball players with a history of unilateral ankle injury and 12 male adolescent volleyball players without a history of unilateral ankle injury was participated. Plantar pressure characteristics and static balance in volleyball players with and without history of unilateral ankle injury was recorded before and after a fatigue from consecutive jumping and landing protocol while standing static on foot pressure. maximum pressure, mean pressure, pressure distribution, surface and romberg open and close eyes balance registered. There was a significant difference between the maximum and the mean plantar pressure and the contact surface of the right foot before and after fatigue and significant difference between the mean pressure and the pressure distribution of the healthy foot and the injured leg in individuals with a history of ankle injury also fatigue cause reduce balance in adolescent volleyball players without history of unilateral ankle injury in open eyes mode and reduce balance in adolescent volleyball players with history of unilateral ankle injury in open and closed eyes. These changes could lead to lower limb injuries.
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- 2020
40. Gene-expression programming for the assessment of surface mean pressure coefficient on building surfaces
- Author
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Awadhesh Kumar, Kanhu Charan Patra, Abinash Mohanta, and Monalisa Mallick
- Subjects
Surface (mathematics) ,Aspect ratio ,Mathematical analysis ,0211 other engineering and technologies ,Mean pressure ,02 engineering and technology ,Building and Construction ,Curvature ,Pressure coefficient ,Angle of incidence (optics) ,021105 building & construction ,021108 energy ,Gene expression programming ,Energy (miscellaneous) ,Wind tunnel ,Mathematics - Abstract
Wind surface mean pressure coefficient (Cp) is an essential parameter for the assessment of wind induced forces that is a must input to all structural designs. An extensive experimentation is carried out to obtain pressure coefficient data over the surfaces of C-shaped building models of varying aspect ratio, corner curvature and angle of incidence in a sub-sonic wind tunnel. The studies also include models without corner curvature. In this study, a technique known as Gene-Expression Programming (GEP) is used to develop a model equation using experimental values of pressure coefficient data collected at the grid points of the frontal surface under varying conditions. And this developed model is used to predict surface mean pressure coefficients (Cp). The predicted values of Cp using the developed model are compared with the corresponding Cp values obtained by Swami and Chandra (S&C) equation and Muehleisen and Patrizi (M&P) equations. The prediction made by the developed GEP model is also validated with the actual building data of Tokyo Polytechnic University (TPU). The results signify the ability of the model to predict the Cp values for practical purposes. The error analysis of the results show that the predicted values of Cp using developed GEP correlation are more close to the experimental values than those obtained by using other two methods.
- Published
- 2020
41. Effect of General Endotracheal Anesthesia and Mechanical Ventilation on the Echocardiographic Measurements in Severe Aortic Stenosis
- Author
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Muralidhar Kanchi, Kumar G. Belani, Rudresh Manjunath, and Pooja Natarajan
- Subjects
Mechanical ventilation ,general endotracheal anesthesia ,business.industry ,medicine.medical_treatment ,Mean pressure ,aortic stenosis ,mechanical ventilation ,medicine.disease ,Stenosis ,Aortic valve area ,Aortic valve replacement ,Anesthesia ,RC666-701 ,medicine ,Breathing ,echocardiography ,Diseases of the circulatory (Cardiovascular) system ,Expiration ,business ,Tidal volume - Abstract
Introduction: We measured the peak pressure gradient (pPG) and mean pressure gradient (mPG) obtained by transesophageal echocardiography (TEE) after induction of anesthesia and compared it with the preoperative pPG and mPG by transthoracic echocardiography (TTE) in adults with aortic stenosis (AS). We also compared the aortic valve area (AVA) measurements as obtained preoperatively by TTE versus those by TEE following induction of general endotracheal anesthesia (GETA) during the inspiratory phase, expiratory phase of the ventilatory cycle and with incremental increases in tidal volume. Materials and Methods: All patients had preoperative TTE within 1 month of surgery and was reviewed 1 day before the surgery. After anesthetic induction, precardiopulmonary bypass (CPB) TEE evaluation was done to measure mPG and pPG across AV, under steady-state conditions. Three different controlled tidal volumes: 8 ml, 10 ml, and 12 ml per kg body weight were utilized during the TEE measurements. Results: A total of 90 adults underwent aortic valve replacement from 2017 to 2018. The preoperative pPG and mPG across the AV by TTE was 96.7 ± 23.27 mmHg and 60.7 ± 18.1 mmHg, respectively. Compared to preoperative TTE, pre-CPB TEE pressure gradient during both phases of ventilation under GETA was significantly lower. The pPG and mPG were higher during inspiration as compared to those in the expiratory cycle during mechanical ventilation under GETA (pPG during inspiration = 66.63 ± 22.15 mmHg; mPG during inspiration = 38.24 ± 13.65 mmHg; pPG during expiration = 52.49 ± 19.10 mmHg; mPG during expiration = 30.76 ± 12.66 mmHg). There were no significant changes in AVA between TTE/TEE and inspiration/expiration. Conclusions: The findings of this study demonstrate that the TEE pre-CPB PGs underestimated the severity of AS; hence, the severity of AS must be interpreted with caution during GETA and mechanical ventilation (MV). In addition, PGs must be done at similar points in the respiratory cycle.
- Published
- 2020
42. Kinetic effect of different ground conditions on the sole of the claws of standing and walking dairy cows
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J. Munzel, Christoph K. W. Mülling, B. Oehme, and S. Grund
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Hoof and Claw ,Claw ,Mean pressure ,Walking ,Standard deviation ,03 medical and health sciences ,Animal science ,Natural rubber ,Floors and Floorcoverings ,Pressure ,Genetics ,Animals ,Curve progression ,Ground reaction force ,030304 developmental biology ,Mathematics ,0303 health sciences ,Mechanical load ,0402 animal and dairy science ,04 agricultural and veterinary sciences ,Housing, Animal ,040201 dairy & animal science ,Pressure sensor ,Dairying ,Kinetics ,visual_art ,visual_art.visual_art_medium ,Cattle ,Female ,Animal Science and Zoology ,Rubber ,Food Science - Abstract
For the first time, we analyzed the direct kinetic effects of concrete and rubber flooring on the soles of live dairy cows' claws while standing and walking. Ten adult dairy cows were equipped with foil-based pressure sensors (HoofSystem, Tekscan Inc., Boston, MA) under their left hind leg using a leather claw shoe. These sensors captured parameters of pressure distribution and vertical ground reaction forces while the cows walked on the 2 tested flooring types. The mean pressure was 15.1 to 21.1% lower on rubber flooring compared with concrete; mean pressure values (± standard deviation) were 36.32 ± 7.77 N/cm2 for static measures and 57.33 ± 11.77 N/cm2 for dynamic measures. We observed an even more obvious relief on rubber flooring in the maximum pressure loads, which were 30.1 to 32.7% lower on rubber flooring compared with concrete; mean pressure values (± standard deviation) were 98.79 ± 14.49 N/cm2 for static measures and 150.45 ± 20.87 N/cm2 for dynamic measures). The force–time curves of the dynamic measures essentially showed biphasic curve progression, with local peaks at 29 and 79% of the stance phase. However, we found considerable differences in curve progression between individuals and between the lateral and medial claws, which may be verified in further investigations with more animals. The study showed a noticeable reduction in mechanical load during standing and walking on rubber flooring compared with concrete.
- Published
- 2019
43. Optimizing Tourniquet Pressure in Upper Extremity Surgery
- Author
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Adam Orengia, Sammy Othman, Michael W Born, Stephen Lopez, and Ashley L Pistorio
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Tourniquet ,business.industry ,Trauma center ,Mean pressure ,Upper extremity surgery ,General Medicine ,Tourniquets ,Upper Extremity ,Pneumatic tourniquet ,Anesthesia ,Cuff ,Pressure ,Occlusion pressure ,Medicine ,Humans ,Prospective Studies ,business ,Tourniquet application - Abstract
Background: Pneumatic tourniquet is an effective tool to achieve hemostatic control of the surgical field in upper extremity (UE) operations. Elevated pressures have been associated with adverse effects despite various methods of pressure determination. We aim to demonstrate the usage of reduced tourniquet pressures and examine factors associated with achieving reduced pressures. Methods: A prospective study was conducted (2016–2018) at a Level 1 Trauma Center and an Outpatient Surgical Center, totaling 226 operations, involving a reduction of cuff pressures over time from a standard baseline of limb occlusion pressure for UE operations. Results: A gradual reduction of pressures was successfully achieved with a mean pressure of 187 mmHg and average time of tourniquet application being 25 minutes. We found chronological surgical number and patient BMI to be significantly associated with tourniquet pressure (p < 0.05). 4.5% of cases resulted in breakthrough bleeding, but did not reliably occur with any pressure thresholds, patient demographics, or operative factors (p > 0.05, for all). Conclusions: Reduced tourniquet pressures can mitigate complications associated with tourniquet use. Our research shows reduced pressures are successful in maintaining field visibility and we encourage an adoption of pressures below 200 mm Hg in most procedures that require a tourniquet.
- Published
- 2021
44. A computational model of contributors to pulmonary hypertensive disease: impacts of whole lung and focal disease distributions
- Author
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Eric A. Hoffman, Merryn H. Tawhai, Kelly Burrowes, Behdad Shaarbaf Ebrahimi, Alys R. Clark, Margaret L. Wilsher, Haribalan Kumar, and David Milne
- Subjects
computational modeling ,Pulmonary and Respiratory Medicine ,medicine.medical_specialty ,vascular remodeling ,Mean pressure ,Disease ,Diseases of the respiratory system ,Internal medicine ,medicine.artery ,pulmonary hypertension ,medicine ,Diseases of the circulatory (Cardiovascular) system ,Original Research Article ,Lung ,RC705-779 ,business.industry ,Blood flow ,medicine.disease ,Pulmonary hypertension ,Hypertensive disease ,medicine.anatomical_structure ,pulmonary circulation ,RC666-701 ,Pulmonary artery ,Etiology ,Cardiology ,business - Abstract
Pulmonary hypertension has multiple etiologies and so can be difficult to diagnose, prognose, and treat. Diagnosis is typically made via invasive hemodynamic measurements in the main pulmonary artery and is based on observed elevation of mean pulmonary artery pressure. This static mean pressure enables diagnosis, but does not easily allow assessment of the severity of pulmonary hypertension, nor the etiology of the disease, which may impact treatment. Assessment of the dynamic properties of pressure and flow data obtained from catheterization potentially allows more meaningful assessment of the strain on the right heart and may help to distinguish between disease phenotypes. However, mechanistic understanding of how the distribution of disease in the lung leading to pulmonary hypertension impacts the dynamics of blood flow in the main pulmonary artery and/or the pulmonary capillaries is lacking. We present a computational model of the pulmonary vasculature, parameterized to characteristic features of pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension to help understand how the two conditions differ in terms of pulmonary vascular response to disease. Our model incorporates key features known to contribute to pulmonary vascular function in health and disease, including anatomical structure and multiple contributions from gravity. The model suggests that dynamic measurements obtained from catheterization potentially distinguish between distal and proximal vasculopathy typical of pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension. However, the model suggests a non-linear relationship between these data and vascular structural changes typical of pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension which may impede analysis of these metrics to distinguish between cohorts.
- Published
- 2021
45. Predictors of Procedural Success in Patients With Degenerated Surgical Valves Undergoing Transcatheter Aortic Valve-in-Valve Implantation
- Author
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Samir R. Kapadia, Shashank Shekhar, Zoran B. Popović, Anas M. Saad, Rishi Puri, Medhat Farwati, Grant W. Reed, Omar M Abdelfattah, Amar Krishnaswamy, James Yun, Abdelrahman Ibrahim Abushouk, and Toshiaki Isogai
- Subjects
valve-in-valve ,medicine.medical_specialty ,Multivariate analysis ,Transcatheter aortic ,business.industry ,Mean pressure ,aortic stenosis ,Regurgitation (circulation) ,Cardiovascular Medicine ,Surgical valves ,Valve in valve ,TAVI ,transcatheter ,Sample size determination ,RC666-701 ,Internal medicine ,Cardiology ,Diseases of the circulatory (Cardiovascular) system ,Medicine ,procedural success ,In patient ,business ,Cardiology and Cardiovascular Medicine ,Original Research - Abstract
Background: Valve-in-Valve transcatheter aortic valve implantation (ViV-TAVI) is a growing alternative for redo-surgery in patients with degenerated surgical valves. To our knowledge, data are lacking on the determinants on ViV-TAVI procedural success in patients with degenerated surgical valves.Methods: All consecutive patients undergoing ViV-TAVI for degenerated surgical valves at the Cleveland Clinic were analyzed. Data were extracted from our patient registry on baseline patient characteristics, echocardiographic parameters, and procedural details. To identify possible predictors of ViV-TAVI procedural success, we employed a multivariate logistic regression model.Results: A total of 186 patients who underwent ViV-TAVI were analyzed, with procedural success (VARC-2 device success and absence of periprocedural MACCE) reported in 165 (88.7%) patients. Patients with successful ViV-TAVI were significantly younger and had more frequent utilization of the transfemoral access than those with failed procedure. Other baseline and procedural characteristics were comparable between both groups. In terms of echocardiographic parameters, the procedural success group had a significantly lower AV peak pressure gradient (62.1 ± 24.7 vs. 74.1 ± 34.6 mmHg; p = 0.04) and lower incidence of moderate-to-severe aortic regurgitation [AR] (30.4 vs. 55%; p = 0.04). However, no significant differences between both groups were noted in terms of AV mean pressure gradient and left ventricular measurements. In multivariate analysis, lower AV peak pressure gradient (OR = 0.97, 95% CI: 0.95–0.99) and absence of moderate-to-severe AR (OR = 0.65, 95% CI: 0.44–0.95) at baseline emerged as independent predictors of ViV-TAVI procedural success.Conclusion: Valve-in-Valve TAVI for degenerated surgical valves is a feasible approach with high success rates, especially in those with lower AV peak pressure gradient and absence of moderate-to-severe AR. Studies with larger sample size and longer follow-up are required to further characterize the predictors of ViV-TAVI success and other clinical outcomes.
- Published
- 2021
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- View/download PDF
46. Discordant moderate aortic stenosis: is it clinically important?
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Benoy N. Shah and Roxy Senior
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Male ,medicine.medical_specialty ,diagnostic imaging ,Mean pressure ,aortic valve stenosis ,Cardiac catheterisation ,Doppler echocardiography ,heart valve diseases ,Severity of Illness Index ,Ventricular Function, Left ,Internal medicine ,medicine ,Humans ,echocardiography ,Registries ,Aged ,medicine.diagnostic_test ,business.industry ,Effective orifice area ,Stroke Volume ,Gold standard (test) ,medicine.disease ,Prognosis ,Stenosis ,Editorial ,Aortic valve stenosis ,Aortic Valve ,Valvular Heart Disease ,Cardiology ,Female ,Hypertrophy, Left Ventricular ,Cardiology and Cardiovascular Medicine ,business - Abstract
Background The criteria to define the grade of aortic stenosis (AS)—aortic valve area (AVA) and mean gradient (MG) or peak jet velocity—do not always coincide into one grade. Although in severe AS, this discrepancy is well characterised, in moderate AS, the phenomenon of discordant grading has not been investigated and its prognostic implications are unknown. Objectives To investigate the occurrence of discordant grading in patients with moderate AS (defined by an AVA between 1.0 cm² and 1.5 cm² but with an MG
- Published
- 2021
47. Experimental investigation of the aerodynamics of a large industrial building with parapet
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Hamzeh Gol-Zaroudi, Matthew Thomas, and Aly Mousaad Aly
- Subjects
business.industry ,Open-jet testing ,Bubble ,Open terrain ,Mean pressure ,Parapet ,TL1-4050 ,General Medicine ,Structural engineering ,Aerodynamics ,Flow pattern ,Wind direction ,Engineering (General). Civil engineering (General) ,Turbulence ,Environmental science ,Low-rise buildings ,TA1-2040 ,Pressure measurement ,business ,Roof ,Motor vehicles. Aeronautics. Astronautics - Abstract
The aerodynamic performance of a roof depends significantly on its shape and size, among other factors. For instance, large roofs of industrial low-rise buildings may behave differently compared to those of residential homes. The main objective of this study is to experimentally investigate how perimeter solid parapets can alter the flow pattern around a low-rise building with a large aspect ratio of width/height of about 7.6, the case of industrial buildings/shopping centers. Solid parapets of varied sizes are added to the roof and tested in an open-jet simulator in a comparative study to understand their impact on roof pressure coefficients. Roof pressures were measured in the laboratory for cases with and without parapets under different wind direction angles (representative of straight-line winds under open terrain conditions). The results show that using a parapet can alter wind pressures on large roofs. Parapets can modify the flow pattern around buildings and change the mean and peak pressures. The mean pressure pattern shows a reduction in the length of the separation bubble due to the parapet. The parapet of 14% of the building’s roof height is the most efficient at reducing mean and peak pressures compared to other parapet heights.
- Published
- 2021
48. Alterations in plantar pressure after a protocol of neuromuscular fatigue in isoinertial machine
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Leonardo Rodriguez Perdomo, Camilo Andres Rincón Yepes, and Miller Esneyder Vargas Santiago
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Complementary and Manual Therapy ,Centro de masa ,Mean pressure ,Physical Therapy, Sports Therapy and Rehabilitation ,Squat ,Center of mass ,Education ,Occupational Therapy ,Medicine ,Isoinertial ,7 Bellas artes::79 - Diversiones. Espectáculos. Cine. Teatro. Danza. Juegos.Deportes [CDU] ,Orthopedics and Sports Medicine ,Pre and post ,Baropodometría ,Orthodontics ,Estabilidad ,business.industry ,Isoinercial ,Neuromuscular fatigue ,Baropodometry ,GV557-1198.995 ,Contact surface ,Superficies de contacto ,business ,Stability ,Sports - Abstract
El objetivo del presente estudio fue establecer las diferencias que se presentan en la huella plantar tras aplicar un protocolo de fatiga neuromuscular. Un total de 10 deportistas varones sanos con una edad aproximada de 21 años fueron evaluados para el componente morfológico, con el equipo Tanita BC585F® (variables: kg de peso, kg de grasa, kg de músculo y kg de hueso). En el protocolo de fatiga se utilizó el equipo isoinercial Squat RSP®. Para la prueba de baropodometría, tanto en el pre-test como en el post-test, se utilizó el equipo EcoWalk. Se tomaron variables de presión R-Type® para ambos pies, como presión media, superficie de contacto, distribución anterior, posterior, lateral derecha y lateral izquierda. No se encontraron diferencias significativas en el pre y post test de la prueba de baropodometría con una p>0.05. Se encontraron correlaciones significativas entre el componente morfológico y la baropodometría con una p The objective of the present study sought to establish the differences presented in the plantar footprint after applying a neuromuscular fatigue protocol. A total of 10 healthy male athletes with an approximate age of 21 years were evaluated for the morphological component, with the Tanita BC585F® equipment (variables: weight Kg, fat KG, muscle Kg and bone Kg). In the fatigue protocol, the isoinertial Squat RSP® equipment was used. For the baropodometry test, both in the pre-test and in the post-test, the EcoWalk equipment was used. R-Type® pressure variables were taken for both feet, such as mean pressure, contact surface, anterior, posterior, right lateral and left lateral distribution. No significant differences were found in the pre and post test of the baropodometry test with a p> 0.05. Significant correlations were found between the morphological component and the baropodometry with a p
- Published
- 2021
49. Loeffler’s group 2 cor triatriatum sinistrum with mobile left atrial thrombus – a case report and literature review
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Wei Zhu, Dongqun Lin, Yuan Zheng, and Xinjie Huang
- Subjects
Adult ,Male ,medicine.medical_specialty ,Mean pressure ,030204 cardiovascular system & hematology ,Cor Triatriatum Sinistrum ,03 medical and health sciences ,0302 clinical medicine ,Left atrial ,Cor Triatriatum ,Internal medicine ,Humans ,Medicine ,Atrial Appendage ,In patient ,Heart Atria ,cardiovascular diseases ,Left atrial thrombus ,Stroke ,Surgical repair ,business.industry ,Thrombosis ,General Medicine ,medicine.disease ,Cor triatriatum sinister ,030228 respiratory system ,Echocardiography ,Pediatrics, Perinatology and Child Health ,cardiovascular system ,Cardiology ,Cardiology and Cardiovascular Medicine ,business - Abstract
We report a case of a 25-year-old man diagnosed with an unusual case of cor triatriatum sinister with a mobile left atrial thrombus. He was hospitalised with aggravating dyspnoea. Transthoracic echocardiography revealed a membrane-like structure traversing the left atrial and a small orifice of about 7.1 mm. The mean pressure gradient was 12.94 mmHg across the orifice of the membrane-like structure and there was a mobile mass in the post-erosuperior chamber. The anomaly was rectified by a surgical resection. Timely diagnosis and surgical repair may prevent stroke in patients with unusual cor triatriatum sinister.
- Published
- 2020
50. BMI is a Better Indicator of Cardiac Risk Factors, as against Elevated Blood Pressure in Apparently Healthy Female Adolescents and Young Adult Students: Results From a Cross-Sectional Study in Tripura.
- Author
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Debnath, Surajit
- Abstract
among populations. This study was undertaken to identify the better indicator of Cardiac-risk factors by statistical comparison of BMI, Waist circumference, and Waist to Height (WtHr) ratio in apparently healthy adolescents and young adult female students of Tripura. Materials and Methods: A cross-sectional study was conducted in a resource limited setup on 210 apparently healthy female adolescents and young adult students in Tripura. Mean (±SD) of all parameters were compared (ANOVA) to recognize significant independent (anthropometric measures) and dependent factors (blood pressure indices and so on). Correlation (r) analysis was used to identify the better (p) indicator of blood pressure indices (dependent variable) and its impact was assessed by Multiple Regression analysis. Results: blood pressure indices are comparatively higher in obese and overweight participants with statistically significant (95.5% confidence) mean differences. Significant correlation with dependent factors is observed with BMI followed by WtHr and Waist Circumference. Impact of anthropometric measures with blood pressure Indices is most significant for BMI (P ≤ 0.020) followed by WtHr (P ≤ 0.500) and waist circumference (P ≤ 0.520). Conclusion: BMI is a superior indicator of blood pressure indices and can identify participants at risk even in apparently healthy adolescent and young adult females. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
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