Journal articles on the topic 'Pressure arch'
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Shoukas, A. A., M. J. Brunner, A. S. Greene, and C. L. MacAnespie. "Aortic arch reflex control of total systemic vascular capacity." American Journal of Physiology-Heart and Circulatory Physiology 253, no. 3 (September 1, 1987): H598—H603. http://dx.doi.org/10.1152/ajpheart.1987.253.3.h598.
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The ability of the aortic arch baroreceptors to change vascular capacity was measured and, in the same animal, compared with carotid sinus reflex changes in capacity. Seven dogs were anesthetized with pentobarbital sodium and perfused with constant flow. Changes in external reservoir volume reflected reciprocal changes in total systemic vascular capacity and changes in arterial pressure parallel changes in total peripheral resistance. The aortic arch and carotid sinus baroreceptor areas were isolated, and the pressures were controlled separately. With carotid sinus pressure held constant at 125 mmHg, aortic arch pressure was increased and decreased between 225 and 50 mmHg, and the changes in reservoir volume and systemic arterial pressure were measured. Results from increasing and decreasing aortic arch or carotid sinus pressure were not significantly different and were averaged. The mean change in reservoir volume was 1.9 +/- 0.2 ml/kg and the change in mean arterial pressure was 18.7 +/- 3.7 mmHg. The changes in reservoir volume and arterial pressure caused by the aortic arch reflex were not influenced by the level of carotid sinus pressure. Carotid sinus pressure changes between 200 and 50 mmHg at a constant aortic arch pressure caused reservoir volume and arterial pressure to change by 7.2 +/- 0.9 ml/kg and 45.1 +/- 4.1 mmHg, respectively. The level of aortic arch pressure did not modify these responses.
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Wang, S. R., X. G. Wu, Y. H. Zhao, P. Hagan, and C. Cao. "Evolution Characteristics of Composite Pressure-Arch in Thin Bedrock of Overlying Strata During Shallow Coal Mining." International Journal of Applied Mechanics 11, no. 03 (April 2019): 1950030. http://dx.doi.org/10.1142/s1758825119500303.
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Under the shallow coal mining condition and based on the cracking and movement rules of the roof in different mining stages, the mechanical models of symmetrical pressure-arch, stepped pressure-arch, rotating-squeezed pressure-arch in the mining field were established. Then, the instability criterion of each pressure-arch structure was derived. Through the similarity material experiment and numerical simulation, the evolution characteristics of the composite pressure-arches in the near- and far-field were revealed. Results show that the stepped pressure-arch in broken blocks of the basic roof was formed when the horizontal principal stress was greater than the in-situ stress. The broken blocks’ sliding could induce roof cutting off and strong weighting load. The structural characteristics of the overlying strata were determined by the thickness of the bedrock. The upper broken rocks formed a symmetrical pressure-arch in the near- and a far-field pressure-arch formed in the mining field. The median periodic broken rocks formed the rotating-squeezed pressure-arch, bearing the load of the loose layers and protecting the mining panel. After all bedrocks breaking, the latter arch foot of the far-field pressure-arch was transferred to the compacted caving zone. This study can provide a theoretical reference for the similar mining engineering.
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Zhao, Yanhai, Shuren Wang, Paul Hagan, Lianwei Ren, and Zhengsheng Zou. "Pressure-Arching Characteristics in Roof Blocks during Shallow Coal Mining." Advances in Civil Engineering 2018 (September 16, 2018): 1–12. http://dx.doi.org/10.1155/2018/6817059.
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To reveal the performance of the stepped subsidence and the strong roof weighting during shallow coal mining, taking the fully mechanized mining face with large mining height in the Shendong mining area in China as the engineering background, theoretical analysis and numerical simulation were used to analyze the pressure-arching effect of the hanging roof blocks. Three typical pressure-arch models of the roof structure were proposed, such as the symmetrical pressure-arch of two key blocks, the step pressure-arch of multiple key blocks, and the rotative pressure-arch of multiple key blocks. Results indicate that the horizontal stress displays a nonlinear distribution at the abutments of the symmetrical pressure-arch, and there is a linear distribution of horizontal stress with a higher peak value at the midspan of the pressure-arch. The high horizontal stress at the arch abutment is necessary to form the rotative pressure-arch of multiple key blocks. The horizontal stress is relatively less at the arch abutment of the step pressure-arch structure. The main key block is easier to slide in this structure as the boundary horizontal stresses display the nonlinear distribution. The results are of instructive significance for roof weighting forecast and strata control during shallow horizontal mining for a thick coal seam.
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Li, Da Peng, Chuan An Cui, Cheng Hui Duan, and Jian Kui Zhao. "Theoretical Analysis on Pressure Arch Boundary around Circular Tunnel." Applied Mechanics and Materials 256-259 (December 2012): 1191–94. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.1191.
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Pressure arch is a phenomenon of rock mass stress restructuring to display itself bearing capacity, one of the important aspects is determination of the pressure arch boundary, and now the main method to determine the pressure arch boundary is numerical analysis. In order to determine the pressure arch boundary theoretically, a circular tunnel is taken as analyzing model, and the secondary stress condition around the rock mass is analyzed, also the equations of horizontal stress and vertical stress are deduced, and then the variation regulation of horizontal stress and vertical stress are discussed. On this basis, 3 kinds of pressure arch boundary determination methods are researched, and the boundaries of each method are found out, finally, the differences of the methods are compared. The results show that every determination method of pressure arch boundary has its own rationality, and they can provide reference for engineering and new arch boundary determination method.
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SHIMIZU, Shingo, Chikara NAGAI, Eiichi GENDA, and Goro OBINATA. "Comparison of Plantar Pressure and Center of Pressure of the Normal Arch and Row Arch." Journal of Japan Society of Sports Industry 23, no. 2 (2013): 2_177–2_182. http://dx.doi.org/10.5997/sposun.23.2_177.
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Joubert-Huebner, E., A. Gerdes, and H.-H. Sievers. "An in vitro evaluation of a new cannula tip design compared with two clinically established cannula-tip designs regarding aortic arch vessel perfusion characteristics." Perfusion 15, no. 1 (January 2000): 69–76. http://dx.doi.org/10.1177/026765910001500110.
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We investigated in vitro aortic arch vessel perfusion characteristics of single and multiple jet-stream cannulae and a new dispersion stream tip aortic cannula. Pressures and flows of all arch vessels were measured while directing cannulae jets at the different arch vessels using 6 l/min pump flow. The highest increase in pressure above the set systemic level of 80 mmHg and increase in flow above the set normal flow distribution in the arch vessels occurred in the jet-streamed arch vessels with the single stream cannula. The values were as follows: 29 mmHg and 118 ml/min for the innominate artery, 28 mmHg and 42 ml/min for the left common carotid artery, and 25 mmHg and 54 ml/min for the left subclavian artery. The dispersion stream cannula showed increases in pressure and flow, followed by the multiple stream cannula. Aortic cannula tips and the orientation of jets are potential sources of imbalances of arch vessel perfusion with possible clinical implications regarding perfusion of arch vessels during extracorporeal circulation.
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Wang, Shuren, Xiaogang Wu, Yanhai Zhao, and Paul Hagan. "Mechanical Performances of Pressure Arch in Thick Bedrock during Shallow Coal Mining." Geofluids 2018 (October 1, 2018): 1–13. http://dx.doi.org/10.1155/2018/2419659.
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Due to the periodicity of mine pressure, it can easily lead to a wide-range damage of the overburden rock under shallow coal mining conditions, and the falling of the overburden rock is usually a serious threat to the mining safety. Based on the monitoring data of mine pressure in a typical shallow coal mine in northern China, the mechanical model of the surrounding rock in the mining field was built and the identification indicators of the pressure arch after coal mining was defined. Then, the arching mechanism, the stress distribution characteristics in different positions, and the bearing capacity of the pressure arch were analysed, and the evolution characteristics of the pressure arch under shallow horizontal coal mining were verified by numerical simulation and physical experiment. Results show that there is a core-bearing zone in the pressure arch, and the width of the core zone determines the bearing capacity of the pressure arch. The evolution of the pressure arch affects the formation and development of the caving arch of the loose zone in the mining field. The conclusions obtained in the study are of important theoretical value to direct the similar engineering practice.
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Pivirotto, Mia, Michael F. Swartz, Megan B. McGreevy, Nader Atallah-Yunes, Jill M. Cholette, Steven E. Lipshultz, and George M. Alfieris. "Factors Associated With an Abnormal Blood Pressure Response During Exercise After Coarctation Repair." World Journal for Pediatric and Congenital Heart Surgery 13, no. 1 (December 17, 2021): 53–59. http://dx.doi.org/10.1177/21501351211060351.
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Background Although resting blood pressures following aortic arch repair or the extended end-to-end anastomosis (EEA) repair for coarctation can be physiologic, factors associated with an abnormal blood pressure response after exercise are unknown. We measured blood pressure gradients following exercise in children who had undergone previous repair in accordance with a surgical selection algorithm and sought to identify factors associated with an abnormal blood pressure response. Methods In accordance with our practice's surgical algorithm for repair of coarctation, infants were stratified to aortic arch repair when the distal transverse arch-to-left carotid artery ratio (DTA:LCA) ≤ 1.0, or when a brachiocephalic trunk or intra-cardiac lesion requiring repair was present. A thoracotomy and EEA were otherwise used. A follow-up exercise stress test (EST) measured the arm:leg blood pressure gradient after exercise, and a gradient ≥ 20 mm Hg was defined as an abnormal blood pressure response. Results Thirty-seven infants who had previously undergone coarctation repair (aortic arch repair-19, EEA-18) completed an EST at 12.3 ± 2.2 years of age. Thirteen (35%) children (aortic arch repair-5, EEA-8; p = .3) exhibited an abnormal blood pressure response. Factors associated with an abnormal blood pressure response included: smaller DTA:LCA ratios prior to repair (1.0 ± .2 vs. 1.2 ± .3; p = .04) and greater body weight at the time of EST (57.5 ± 19.1 vs. 40.9 ± 15.6 kg; p = .03). Conclusion An abnormal blood pressure response following exercise is associated with smaller DTA:LCA ratios at the time of repair and increased weight during follow-up suggesting that patients with these factors warrant close observation.
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Tian, Chao, Yong Gang Li, and Zhi Xiong Zhang. "Arch with Various Wall Movements in Active Earth Pressure Abstract." Advanced Materials Research 1089 (January 2015): 286–91. http://dx.doi.org/10.4028/www.scientific.net/amr.1089.286.
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For the retaining wall in translation, in this paper the writers present the minor principal stresses trajectory which named minor principal stress arches. By discussing the results of the various arch curves in arching effect with different displacements of retaining wall which include the arch curves in ultimate model of soil and the arch curves in none limit state of soil. It gets the soil arch curve change rule under different state of the displacements, different friction angles and different height: the arch curve turn gentle when the displacements increase.
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Yaremenko, Olena. "Сalculation methodology and determination of efforts in vault." Bulletin of Kharkov National Automobile and Highway University 2, no. 92 (May 10, 2021): 85. http://dx.doi.org/10.30977/bul.2219-5548.2021.92.2.85.
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Abstract. Problem. In this article we offer the meth-odology of calculation, based on the idea of dismem-berment of vault on the separate archs of single width. It is recommended for the estimation of efforts in the designed and damaged vaults. Also offered a methods of calculation effort in serried vaults. As spatial inflexibility of cross vault below than inflexi-bility of serried vault, then it is necessary to execute the calculation of the cheek arch abstracted from the tray of cross vault also. If the outline of tray is exe-cuted on a circular curve, then it is possible to take methodology of calculation of archs with the outline of axis a curve as catenoid. Goal. The proposed methodology for calculating closed and cross vaults is also based on the idea of dividing the arch into separate arches of unit width. The results of studies of efforts and rational forms of arches of V.A. Kiselev [1]. Methodology. Calculation based on the idea of dismemberment of vault on the separate archs of single width. Recommended for the estimation of efforts in the designed and damaged vaults. A method over of calculation of dome is brought for determina-tion of effort in serried vaults. Results. At the choice of outline of axis of arch it is necessary aspires to that an axis, on possibility, coincided with the curve of pressure. Such outline of axis is rational, as there are only central forces of N in an arch. Flexion mo-ments M and transversal forces of Q are equal to the zero. The coincidence of axis of arch with the curve of pressure can be got for the three-hinged arch. For the statically undetermined arch of complete coinci-dence of axis with the curve of pressure attaining is impossible, so that the origin of flexion moments at any her outline is inevitable. Originality. The tech-nique based on the separation of flat elements from the spatial structure does not show the reserves of strength of the structure. Experience of long-term operation of vaulted structures designed or verified by calculation using similar methods [2], [9] shows caution and reliability. Practical value. The tech-nique is also suitable for assessing the strength of damaged vaults with collapsed corners or walms.
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Otman, S., O. Basgöze, and Y. Gökce-Kutsal. "Energy cost of walking with flat feet." Prosthetics and Orthotics International 12, no. 2 (August 1988): 73–76. http://dx.doi.org/10.3109/03093648809078203.
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A comparative study has been conducted to assess the effects of arch support on oxygen consumption in 20 subjects with flat feet who were generally complaining about fatigue, and also to explore whether their feeling of weariness was objective or not. The resting, walking and final recovery heart rates, blood pressures, and walking oxygen consumption values of the patients with flat feet were measured and calculated and compared to a control group using treadmill and oxygen consumption devices. In stage one the patients did not wear any arch support. Then suitable arch supports were prepared for each patient and in stage two they wore these arch supports. The results did not show any significant difference between the resting heart rates, blood pressure and oxygen consumptions. However, differences in walking heart rate, systolic blood pressure, final recovery heart rate, oxygen consumption, and energy cost values were found to be significant between stage one and two of the test in the patient group. The difference in walking diastolic blood pressure values without and with arch support were found to be insignificant. It may therefore be deduced that oxygen consumption during walking is decreased when a suitable arch support is applied to patients with flat feet.
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Farzadi, Maede, Zahra Safaeepour, Mohammad E. Mousavi, and Hassan Saeedi. "Effect of medial arch support foot orthosis on plantar pressure distribution in females with mild-to-moderate hallux valgus after one month of follow-up." Prosthetics and Orthotics International 39, no. 2 (February 10, 2014): 134–39. http://dx.doi.org/10.1177/0309364613518229.
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Background:Higher plantar pressures at the medial forefoot are reported in hallux valgus. Foot orthoses with medial arch support are considered as an intervention in this pathology. However, little is known about the effect of foot orthoses on plantar pressure distribution in hallux valgus.Objectives:To investigate the effect of a foot orthosis with medial arch support on pressure distribution in females with mild-to-moderate hallux valgus.Study design:Quasi-experimental.Methods:Sixteen female volunteers with mild-to-moderate hallux valgus participated in this study and used a medial arch support foot orthosis for 4 weeks. Plantar pressure for each participant was assessed using the Pedar-X®in-shoe system in four conditions including shoe-only and foot orthosis before and after the intervention.Results:The use of the foot orthosis for 1 month led to a decrease in peak pressure and maximum force under the hallux, first metatarsal, and metatarsals 3–5 ( p < 0.05). In the medial midfoot region, peak pressure, maximum force, and contact area were significantly higher with the foot orthosis than shoe-only before and after the intervention ( p = 0.00).Conclusion:A foot orthosis with medial arch support could reduce pressure beneath the hallux and the first metatarsal head by transferring the load to the other regions. It would appear that this type of foot orthosis can be an effective method of intervention in this pathology.Clinical relevanceFindings of this study will improve the clinical knowledge about the effect of the medial arch support foot orthosis used on plantar pressure distribution in hallux valgus pathology.
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Zhang, Yang, Ai Qing Wu, and Zhi Hong Dong. "Simulation of Kinematic Movement for Invert Arch Floor of Plunge Pool with Numerical Manifold Method." Advanced Materials Research 295-297 (July 2011): 2511–14. http://dx.doi.org/10.4028/www.scientific.net/amr.295-297.2511.
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The invert arch floor of large plunge pool is composed of some discrete arch blocks divided by construction joints. The joint is only 1 mm wide. Under the uplift pressure, the mechanical behavior belongs to highly nonlinear problem, which is difficult to simulate by finite element method. Based on NMM (numerical manifold method), the kinematic motion process of the invert arch floor is simulated under the different uplift pressure. Calculation results show that: as the uplift pressure increasing, each arch block gradually rises, rotates, contacts with adjacent blocks and the expansion joint width between adjacent blocks reduces. When uplift pressure reaches 85Kpa, the mutation of expansion joint width emerges and the invert arch floor finishes self-lock process which indicating the invert arch floor start playing statically indeterminate role to keep stable. The bearing capacity of the floor is determined by concrete compressive strength and anchoring strength of two arch abutments.
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Du, Xiao Li, Hong Wei Song, and Jie Chen. "Laws of Formation and Evolution of Pressure Arch in Coal Mining Adjoining Rock." Advanced Materials Research 243-249 (May 2011): 2596–600. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.2596.
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Based on numerical simulation of computing Software ANSYS, the curve of arching coefficient variation of pressure arch due to actual mining was analyzed aiming to a special mining face, the law of stress transfer and change in surrounding rock was discussed, and the evolving features and characteristics of pressure arch was obtained. The analysis and discussion show the following facts: Arch body will become thicker and stress in the arch body increases with working face’s driving distance increasing; the morphology of pressure arch transits from ellipsoid with long axis in the vertical direction to ellipsoid with long axis in the horizontal direction along the trend of working face; along the tendency of working face, the morphology of pressure arch is a ellipsoid with long axis in the vertical direction.
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Zhang, Yun, and Bei Li. "The Filler Application of Light Weight Aggregate Concrete in Double-Curved Arch Bridge Reinforcement." Applied Mechanics and Materials 166-169 (May 2012): 1626–29. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.1626.
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The basic principle of arch bridge design is high level concord of 5 points between arch axial line and the pressure line. Taking lightweight aggregate concrete as arch crown filler, the casting area is divided into arch spandrel area and arch crown area. Through adjusting filler weight density, the arch axial line and pressure line can be adjusted to decrease the difference between them. The force condition of main arch bridge gets improved. The method can reinforce double-curved arch bridge together with increasing section method. It is seen that the property of arch ring masonry material got a full play. Bridge durability and comfort degree improved significantly.
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Wu, Ting-Ting, Shin-Liang Lo, Hui Chen, Jeng-Sheng Yang, and Hsien-Te Peng. "Arch-Support Insoles Benefit the Archery Performance and Stability of Compound Archers." International Journal of Environmental Research and Public Health 19, no. 14 (July 10, 2022): 8424. http://dx.doi.org/10.3390/ijerph19148424.
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The purpose of this study was to analyze the effects of the use of arch-support insoles on the archery performance and center of plantar pressure (CoP) excursion in compound archers. Fifteen highly skilled compound archers were the subjects. A pressure plate was used to measure the CoP excursion and percentage distribution of plantar pressure. The parameters were compared between archers wearing flat and arch-support insoles using a paired-sample t-test. The results demonstrated that the shooting score in archers wearing the arch-support insole was significantly greater than in those wearing the flat insoles. The CoP excursion of the left foot, right foot, and both feet in archers wearing the arch-support insole were significantly smaller than in those wearing the flat insole. The distributed percentage of the plantar pressure showed that the arch-support insole significantly reduced the plantar pressure in the left posterior zone by 3.54% compared with the flat insole, and increased the plantar pressure in the right anterior zone by 2.54%. The principal conclusion was that compound archers wearing arch-support insoles during the arrow-release process can reduce the CoP excursion of the foot and increase their shooting score. The plantar pressure was distributed evenly in arch-support insoles.
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Wang, Yingchao, Hongwen Jing, Qiang Zhang, Ning Luo, and Xin Yin. "Prediction of Collapse Scope of Deep-Buried Tunnels Using Pressure Arch Theory." Mathematical Problems in Engineering 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/2628174.
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Tunnel collapse remains a serious problem in practice. Effective prediction methods on tunnel collapse are necessary for tunnel engineering. In this study, systematic study on the pressure arch was presented to predict tunnel collapse. Multiple factors under different conditions were considered. First, the pressure arch was described as a certain scope in comparison with the lowest pressure arch line. Then, a deep-buried circular tunnel was selected as the investigated object. Its collapse scope was analyzed using the lowest pressure arch line. Meanwhile, the main influence from the ground stress field was considered. Different modes of ground stress fields were investigated in detail. The results indicate that the collapse scope varies with different ground stress fields. Determination on the collapse scope is strongly affected by the judgment standard of the pressure arch. Furthermore, a selected case was analyzed with the pressure arch. The area and the height of tunnel collapse were calculated with multiple factors, including ground stress field, judgment standard, and lateral pressure coefficient. Finally, selected results were compared with relevant previous researches, and reasonable results were obtained. The present results are helpful for further understanding of the tunnel collapse and could provide suitable guidance for tunnel projects.
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Kanatli, Ulunay, Haluk Yetkin, and Nadir Yalcin. "The Relationship between Accessory Navicular and Medial Longitudinal Arch: Evaluation with a Plantar Pressure Distribution Measurement System." Foot & Ankle International 24, no. 6 (June 2003): 486–89. http://dx.doi.org/10.1177/107110070302400606.
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This study included 92 patients with an accessory navicular (AN) noted on an anteroposterior roentgenography. This group was selected from 860 patients admitted to the authors' gait analysis laboratory. The medial longitudinal arch was evaluated by using an “arch index” calculated from the pressure picture obtained from a pressure distribution measurement system. The average arch index was 0.15 and there was no significant correlation between AN types and arch index. The study concluded that the presence and type of AN are not correlated with the height of the medial longitudinal arch of the foot and that AN is not associated with pes planus.
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Ezzeldin, Islam, and Hany El Naggar. "Earth pressure distribution around flexible arch pipes." Engineering Structures 237 (June 2021): 112226. http://dx.doi.org/10.1016/j.engstruct.2021.112226.
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Burroughs, P., T. G. Hughes, S. Hee, and M. C. R. Davies. "Passive pressure development in masonry arch bridges." Proceedings of the Institution of Civil Engineers - Structures and Buildings 152, no. 4 (November 2002): 331–39. http://dx.doi.org/10.1680/stbu.2002.152.4.331.
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Prokhorov, I. Yu. "Arch effect in high isostatic pressure compacts." Journal of the European Ceramic Society 19, no. 15 (November 1999): 2619–23. http://dx.doi.org/10.1016/s0955-2219(99)00056-4.
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Warmerdam, E. G., G. J. Krings, T. A. Meijs, A. C. Franken, B. W. Driesen, G. T. Sieswerda, F. J. Meijboom, P. A. F. Doevendans, M. M. C. Molenschot, and M. Voskuil. "Safety and efficacy of stenting for aortic arch hypoplasia in patients with coarctation of the aorta." Netherlands Heart Journal 28, no. 3 (November 29, 2019): 145–52. http://dx.doi.org/10.1007/s12471-019-01353-5.
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Abstract Background Despite a successful repair procedure for coarctation of the aorta (CoA), up to two-thirds of patients remain hypertensive. CoA is often seen in combination with abnormal aortic arch anatomy and morphology. This might be a substrate for persistent hypertension. Therefore, we performed endovascular aortic arch stent placement in patients with CoA and concomitant aortic arch hypoplasia or gothic arch morphology. The goal of this retrospective analysis was to investigate the safety and efficacy of aortic arch stenting. Methods A retrospective analysis was performed in patients who underwent stenting of the aortic arch at the University Medical Center Utrecht. Measurements collected included office blood pressure, use of antihypertensive medication, invasive peak-to-peak systolic pressure over the arch, and aortic diameters on three-dimensional angiography. Data on follow-up were obtained at the date of most recent outpatient visit. Results Twelve patients underwent stenting of the aortic arch. Mean follow-up duration was 14 ± 11 months. Mean peak-to-peak gradient across the arch decreased from 39 ± 13 mm Hg to 7 ± 8 mm Hg directly after stenting (p < 0.001). There were no major procedural complications. Mean systolic blood pressure decreased from 145 ± 16 mm Hg at baseline to 128 ± 9 mm Hg at latest follow-up (p = 0.014). Conclusion This retrospective study shows that stenting of the aortic arch is successful when carried out in a state-of-the-art manner. A direct optimal angiographic and haemodynamic result was shown. No major complications occurred during or after the procedure. At short- to medium-term follow-up a decrease in mean systolic blood pressure was observed.
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Takada, Jun-ichi, Takashi Ono, Shigeki Takahashi, Ei-ichi Honda, and Tohru Kurabayashi. "Changes in Horizontal Jaw Position and Intraoral Pressure." Angle Orthodontist 78, no. 2 (March 1, 2008): 254–61. http://dx.doi.org/10.2319/021207-69.1.
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Abstract Objective: To determine the effect of an imbalance in buccolingual pressure that may be involved in molar dental compensation in the mandible and asymmetry of the dental arch in subjects with facial asymmetry. Materials and Methods: We performed simultaneous measurement of the buccolingual pressure on the mandibular right first molar when subjects without facial asymmetry experimentally shifted the mandible laterally. Buccolingual pressures in the rest position (RP), right-shifted position (RS), and left-shifted position (LS) were compared. Moreover, T1-weighted magnetic resonance images were obtained in RP, RS, and LS. Results: Tongue pressure tended to decrease in the order LS > RP > RS, while cheek pressure tended to increase in the order LS < RP < RS. The tongue/cheek pressure ratio tended to decrease in the order LS > RP > RS. There were significant positive (in RS) and negative (in LS) correlations between displacement of the tongue and tongue pressure. Conclusions: This imbalance in buccolingual pressures in the laterally-shifted mandibular position may partly explain molar dental compensation in the mandible and asymmetry of the dental arch in subjects with facial asymmetry.
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Zheng, Tao, Zhiyong Yu, Jin Wang, and Guodong Lu. "A New Automatic Foot Arch Index Measurement Method Based on a Flexible Membrane Pressure Sensor." Sensors 20, no. 10 (May 20, 2020): 2892. http://dx.doi.org/10.3390/s20102892.
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The foot arch index is an important index to evaluate the health of human feet and the biomechanics line, aiming at addressing the shortcomings of the low efficiency and slow speed of manual foot arch index measurement; in this work, an automatic foot arch index measurement method based on a flexible membrane pressure sensor was proposed. The distribution of plantar pressure data was obtained from the flexible membrane pressure sensor and converted into a digital image. The 8-neighborhood correlation pixel method was proposed to remove the interference of isolated noise points. In order to remove the toes’ data without affecting the foot sole data, the row element association algorithm was proposed. The front and back endpoints of the foot were automatically located to obtain the foot length, and the foot arch index was also automatically obtained based on the foot arch pressure area. Whether it was a high arch foot, flat foot or normal foot, the method proposed in this paper could accurately and quickly distinguish them. The prototype was developed, and its feasibility and validity were verified by a series of tests.
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Goffar, Stephen L., Rett J. Reber, Bryan C. Christiansen, Robert B. Miller, Jacob A. Naylor, Brittany M. Rodriguez, Michael J. Walker, and Deydre S. Teyhen. "Changes in Dynamic Plantar Pressure During Loaded Gait." Physical Therapy 93, no. 9 (September 1, 2013): 1175–84. http://dx.doi.org/10.2522/ptj.20120103.
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Background Lower extremity overuse injuries are detrimental to military readiness. Extremes of arch height and heavy loads carried by military personnel are associated with increased risk for overuse injury. Little is known regarding the impact of load carriage on plantar pressure distributions during gait. Objective The objective of this study was to determine how load carriage affects plantar pressure distributions during gait in individuals with varying arch types. Design A cross-sectional, repeated-measures design was used for the study. Methods The study was performed at a research laboratory at Fort Sam Houston, Texas. Service members who were healthy and weighing ≥70 kg were enrolled in the study. The participants (97 men, 18 women; mean age=31.3 years, SD=5.6; mean weight=86.0 kg, SD=11.0) were categorized as having high-, normal-, or low-arched feet on the basis of published cutoff values for the arch height index. Plantar pressure measurements were obtained with the use of an in-shoe pressure measurement system while participants wore combat boots and walked on a treadmill under 3 loaded conditions (uniform, 20-kg load, and 40-kg load). Maximal force (MaxF) and force-time integral (FTI) were assessed with the use of a 9-sector mask to represent regions of the foot. A 3 × 3 repeated-measures analysis of variance was used for analysis across the levels of load and arch type. Results A significant interaction existed between arch type and load for MaxF and FTI in the medial midfoot, with greater force in low-arched feet. In the medial forefoot, MaxF and FTI were greatest in high-arched feet across all load conditions. In the great toe region, low-arched and normally arched feet had greater MaxF and FTI. The relative distribution of FTI increased proportionately in all regions of the foot regardless of arch type for all load conditions. Limitations The influence of fatigue, greater loads, and different walking speeds was not assessed. Conclusions Regardless of arch type, increases in load did not alter the relative distribution of force over the plantar foot during gait. Participants with high-arched feet had greater force in the medial forefoot region, whereas those with normally arched or low-arched feet had greater force in the great toe region, regardless of load. These differences in force distribution may demonstrate different strategies to generate a rigid lever during toe-off.
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Li, Xin Zhe, Geng Feng Wang, Xin Liang Li, and Zhong Rong Zhu. "Numerical Analysis of Initial Support and Secondary Lining Contact Pressure of Phyllite Tunnel." Advanced Materials Research 884-885 (January 2014): 675–78. http://dx.doi.org/10.4028/www.scientific.net/amr.884-885.675.
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Taking Jin Chuan phyllite tunnel as the research object, and based on numerical simulation of surrounding rock graded III, IV and V, the paper studied the stress characteristics of initial support and four other representative locations such as two arch vault, arch spandrel, arch haunch, and arch foot during and after the process of construction. The paper focuses on the stress characteristics of secondary lining in different locations after stability and the change of stress in different locations of initial lining before and after the secondary lining construction.
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Shadwick, R. E., and J. M. Gosline. "Arterial mechanics in the fin whale suggest a unique hemodynamic design." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 267, no. 3 (September 1, 1994): R805—R818. http://dx.doi.org/10.1152/ajpregu.1994.267.3.r805.
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An analysis of the dimensions of the aortic tree and the mechanical properties of arterial wall tissues in the fin whale (Balaenoptera physalus) is presented. The aortic arch is greatly expanded, having an internal radius at an estimated mean blood pressure (13 kPa) that is 2.5 times greater than that of the descending thoracic aorta. At this pressure, the elastic modulus of the arch wall (0.4 MPa) is 30 times less than that of the descending aorta (12 MPa). Consequently, even though some capacitance is provided anteriorly by the relatively compliant innominate and carotid arteries, > 90% of the arterial capacitance resides in the arch. The characteristic pressure wave velocity (C0) and impedance (Z0) were calculated from vessel dimensions and elasticity. A predicted 20-fold increase in Z0 between the arch and thoracic aorta should provide a major reflecting site, effectively uncoupling the arch from the remainder of the arterial tree. The dimensions of the arch relative to the likely pressure wavelengths within it suggest that it acts like a compliant windkessel that greatly reduces the pulsatility of the inflow to the descending aorta, which itself likely acts as a rigid, tapered manifold. It is suggested that the presence of both a highly compliant arch and a relatively rigid descending aorta is an adaptation for diving.
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Rodrigues, Juliana Rocha, Wesley Albuquerque Craveiro, Thiago Vilela Lemos, Fábio Alessandro Galvão Passos, Osmair Gomes De Macedo, and João Paulo Chieregato Matheus. "Influence of application of the inelastic taping in plantar pressure of runners pronators." Manual Therapy, Posturology & Rehabilitation Journal 12 (March 30, 2014): 160. http://dx.doi.org/10.17784/mtprehabjournal.2014.12.160.
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Background: The excessive motion of subtalar pronation of the foot, can cause stress and burden in tissues of the region, giving origin to aches and microtrauma. In clinical practice, excessive movement has been limited to the use of techniques of bandages applied to the plantar arch. Objective: Was to analyze the influence of rigid bandage in plantar pressure distribution corridors pronators. Method: This is a randomized clinical trial, blinded, with twenty runners pronators (33±7 y, 71±7 kg, 174±6 cm). Technique was applied bandage (rigid - BR) to support the plantar arch, described as antipronation. Plantar pressure data were collected using the F -scan system in three tests run at 9 km/h being: no bandages, rigid taping. We considered seven areas of pressure for data analysis, performed by means of ANOVA for repeated measures followed by paired t test. Results: BR resulted in significant reductions (p<0.05) in contact pressures and peak pressure rearfoot. Conclusion: Thus, we conclude that BR provided decrease in contact pressures and peak pressure foot, being significant on the hindfoot than in the midfoot.
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Cen, Xuanzhen, Datao Xu, Julien S. Baker, and Yaodong Gu. "Effect of additional body weight on arch index and dynamic plantar pressure distribution during walking and gait termination." PeerJ 8 (April 21, 2020): e8998. http://dx.doi.org/10.7717/peerj.8998.
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The medial longitudinal arch is considered as an essential feature which distinguishes humans from other primates. The longitudinal arch plays a supporting and buffering role in human daily physical activities. However, bad movement patterns could lead to deformation of arch morphology, resulting in foot injuries. The authors aimed to investigate any alterations in static and dynamic arch index following different weight bearings. A further aim was to analyze any changes in plantar pressure distribution characteristics on gait during walking and stopping, Twelve males were required to complete foot morphology scans and three types of gait tests with 0%, 10%, 20% and 30% of additional body weight. The dynamic gait tests included walking, planned and unplanned gait termination. Foot morphology details and plantar pressure data were collected from subjects using the Easy-Foot-Scan and Footscan pressure platform. No significant differences were observed in static arch index when adding low levels of additional body weight (10%). There were no significant changes observed in dynamic arch index when loads were added in the range of 20% to 30%, except in unplanned gait termination. Significant maximal pressure increases were observed in the rearfoot during walking and in both the forefoot and rearfoot during planned gait termination. In addition, significant maximum pressure increases were shown in the lateral forefoot and midfoot during unplanned gait termination when weight was increased. Findings from the study indicated that excessive weight bearing could lead to a collapse of the arch structure and, therefore, increases in plantar loading. This may result in foot injuries, especially during unplanned gait termination.
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Cai, Zhou Chun, Chuan Li, Yuan Yu Guan, Wu Fen Chen, Li Jun Guo, Fu Yun Chen, Zhen Gang Zhao, and Tao Xie. "FBG Earth Pressure Sensors Applied in Surrounding Rock Pressure of Tunnel." Applied Mechanics and Materials 351-352 (August 2013): 1173–78. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.1173.
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During the period of tunnel excavation, shoring, forming and long-term operation, stress changes of tunnel surrounding rock are complex, the real-time monitoring of surrounding rock pressure is the key factor in ensuring long-term stability in tunnel. Fiber Bragg grating earth pressure sensors apply in surrounding rock pressure of tunnel which can change the pressure of the surrounding rock into fiber Bragg grating wavelength shift. According to the feature of pressure and temperature in Tian Xin Tunnel, 40 earth pressure sensors are embedded in 20 representative sections and one earth pressure sensor is embedded in each arch shoulder. In addition, one temperature compensation sensor is embedded in each arch crown. During the 235 monitoring days, the biggest daily change of surrounding rock pressure reaches 800 KPa. In 3 months of the sensor installation, the average monthly variation is within 50 KPa. The long-term measurement results indicate that the changes of surrounding rock pressure are different in different locations. When the surrounding rock is close to the excavated and blasted surface the surrounding rock pressure changes largely.
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Lin, Hai, Renshu Yang, Yongliang Li, and Shizheng Fang. "Stability of Coal Pillar and Roof Movement Characteristics in Roadway Backfill Mining." Advances in Civil Engineering 2021 (March 22, 2021): 1–13. http://dx.doi.org/10.1155/2021/5588923.
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In order to explore the stability of coal pillar and the characteristics of roof movement during the process of roadway backfill mining (RBM), the 301 backfilling test working face of Ordos Chahasu coal mine is taken as the background. Based on the expansive pressure arch theory, the evolution process of the stope expansive pressure arch in RBM is studied; by establishing a mechanical model for the stability of coal pillars, the interactions between the height, width, and the maximum number of branches are obtained. When the width and height of the branch are both 5 m, the optimal number of the branches is obtained. Then, by establishing a mechanical model for the subsidence of the immediate roof, the process of the immediate roof subsidence is divided into three stages, namely, the formation stage of the local pressure arch, the merge stage of the pressure arch, and the expansion stage of the pressure arch. In addition, using the numerical method, the alternate bearing process of coal pillars and filling bodies and the change of the maximum supporting stress are studied, and the evolution of the pressure arch bearing structure above the stope and the staged subsidence characteristics of the roof are analyzed. The on-site test showed that the coal pillar has a good stability during the mining process. The maximum stress of the coal pillar is 16.5 MPa, and the maximum stress of the filling body is 9 MPa. The maximum settlement of the immediate roof is 102 mm, indicating that the roof control effect is good. This research will play an important role on engineering practice.
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Hammes, Mary, Andres Moya-Rodriguez, Cameron Bernstein, Sandeep Nathan, Rakesh Navuluri, and Anindita Basu. "Computational modeling of the cephalic arch predicts hemodynamic profiles in patients with brachiocephalic fistula access receiving hemodialysis." PLOS ONE 16, no. 7 (July 14, 2021): e0254016. http://dx.doi.org/10.1371/journal.pone.0254016.
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Background The most common configuration for arteriovenous fistula is brachiocephalic which often develop cephalic arch stenosis leading to the need for numerous procedures to maintain access patency. The hemodynamics that contributes to the development of cephalic arch stenosis is incompletely understood given the inability to accurately determine shear stress in the cephalic arch. In the current investigation our aim was to determine pressure, velocity and wall shear stress profiles in the cephalic arch in 3D using computational modeling as tools to understand stenosis. Methods Five subjects with brachiocephalic fistula access had protocol labs, Doppler, venogram and intravascular ultrasound imaging performed at 3 and 12 months. 3D reconstructions of the cephalic arch were generated by combining intravascular ultrasounds and venograms. Standard finite element analysis software was used to simulate time dependent blood flow in the cephalic arch with velocity, pressure and wall shear stress profiles generated. Results Our models generated from imaging and flow measurements at 3 and 12 months offer snapshots of the patient’s cephalic arch at a precise time point, although the remodeling of the vessel downstream of an arteriovenous fistula in patients undergoing regular dialysis is a dynamic process that persists over long periods of time (~ 5 years). The velocity and pressure increase at the cephalic bend cause abnormal hemodynamics most prominent along the inner wall of the terminal cephalic arch. The topology of the cephalic arch is highly variable between subjects and predictive of pathologic stenosis at later time points. Conclusions Low flow velocity and wall pressure along the inner wall of the bend may provide possible nidus of endothelial activation that leads to stenosis and thrombosis. In addition, 3D modelling of the arch can indicate areas of stenosis that may be missed by venograms alone. Computational modeling reconstructed from 3D radiologic imaging and Doppler flow provides important insights into the hemodynamics of blood flow in arteriovenous fistula. This technique could be used in future studies to determine optimal flow to prevent endothelial damage for patients with arteriovenous fistula access.
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Veselev, Yury A., and Mikhail S. Karabutov. "The results of computer analysis of the wind load acting on the set of rolled profiles." Structural Mechanics of Engineering Constructions and Buildings 15, no. 3 (December 15, 2019): 193–200. http://dx.doi.org/10.22363/1815-5235-2019-15-3-193-200.
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The aim of the research is to numerically determine the effect of wind loads on the roof of the rolled profiles of the MIC-120 system. Methods. There were made some calculations in this article of wind load, acting on rolled metal thin-sheet profiles arch and a comparison of computer modeling and buildings requirement such as Building Rules “Loads and Actions” results. The research was carried out by means of modeling of a virtual wind tunnel with the placement to it a metal thin-sheet profiles arch in consideration of different wind actions such as acting on the arch’s butt end (along a generatrix), as well as athwart on the arch and angularly on it with the arch’s width change from 12 to 24 m. The arch modeling as well as the virtual wind tunnel modeling was based on the COSMOSFloWorks software package by means of the method, stated in the previous publications [2; 11]. The theoretical and methodological basis of the research is the Navier - Stokes equation and the equation of the condition of the fluid medium’s components. Results. The results are, first of all, the calculation of the wind pressure on the arch depending on the trajectory, wind speed in different regions and directions of wind flow, secondly, the comparison of the wind pressure, getting with the help of computer modeling with Building Rules 20.13330.2011 “Loads and Actions” and, finally, matching of results of wind pressure for a plain and ribbed arch with equal geometrical parameters, getting by computer modeling. In compliance with the generated calculations there was drawn a conclusion, that the standard pressure according on Building Rules does not change from arch span, but results of the computer modeling show us a change of the wind pressure from the arch’s span.
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Li, Chunliu, Hao Liu, Shuangjun Xu, Jingtao Li, and Chenhua Zhou. "Load Distribution Characteristics of Surrounding Rock for Double-arch Tunnel Considering Pressure-arch Effect." Journal of Engineering Science and Technology Review 13, no. 2 (April 2020): 99–106. http://dx.doi.org/10.25103/jestr.132.14.
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Xie, Wei. "Application of Finite Element Method for Reinforced Concrete Ribbed Arch Aqueduct Structure Analysis." Applied Mechanics and Materials 101-102 (September 2011): 447–50. http://dx.doi.org/10.4028/www.scientific.net/amm.101-102.447.
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Reinforced concrete ribbed arch aqueduct’s bent is arranged symmetrically on the main arch, load which is transferred from bent to main arch is more homogenous. It can improve force conditions of main arch, and aqueduct is arranged on the bent. That also has the function of longitudinal beam. This paper adopts finite element method to carry out force analysis for Guanping reinforced concrete ribbed arch aqueduct, considering aqueduct weight, water pressure and earthquake effect, etc. researching stress and deformation distribution law of reinforced concrete ribbed arch aqueduct.
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Xiong, Shuping, Ravindra S. Goonetilleke, Channa P. Witana, Thilina W. Weerasinghe, and Emily Yim Lee Au. "Foot Arch Characterization." Journal of the American Podiatric Medical Association 100, no. 1 (January 1, 2010): 14–24. http://dx.doi.org/10.7547/1000014.
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Background: The medial longitudinal arch of the foot is important because it helps protect the foot from injury. Researchers have developed many measures to quantify the characteristics of the arch, and there is ongoing debate about the suitability of these different metrics. This article compares the various measures related to the foot arch, including a new metric, the midfoot dorsal angle, and then investigates the differences in the dimensional measures among various foot types. Methods: The right feet of 48 healthy individuals (24 men and 24 women) were measured, and various metrics, including the arch height index, the navicular height to arch length ratio, the arch index, the footprint index, the subjective ranking, the modified arch index, the malleolar valgus index, and the midfoot dorsal angle, were determined. Results: Correlation analyses showed that the arch index obtained from the inked footprint has a moderate to high correlation (Pearson correlation coefficients >0.50) with all measured foot-type metrics except for the malleolar valgus index. There were no differences in participant age, stature, weight, body mass index, foot length, foot width, and midfoot height among high, normal, and low foot arches. However, the high-arched group had significantly shorter arch lengths but larger navicular heights and higher midfoot dorsal angles compared with the low-arched group. There were differences in force distributions and peak pressures as well. The rearfoot had more loading and greater peak pressure whereas the midfoot had less load in the high-arched group compared with the low-arched group. Conclusions: The midfoot dorsal angle may be an appropriate metric for characterizing the foot arch because it is quick and easy to measure, without the tedious procedures associated with area calculations and dimension measurements. (J Am Podiatr Med Assoc 100(1): 14–24, 2010)
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Pauk, Jolanta, Mikhail Ihnatouski, and Bijan Najafi. "Assessing Plantar Pressure Distribution in Children with Flatfoot Arch." Journal of the American Podiatric Medical Association 104, no. 6 (November 1, 2014): 622–32. http://dx.doi.org/10.7547/8750-7315-104.6.622.
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Background Flatfoot, or pes planus, is one of the most common foot posture problems in children that may lead to lower-extremity pain owing to a potential increase in plantar pressure. First, we compared plantar pressure distribution between children with and without flatfoot. Second, we examined the reliability and accuracy of a simple metric for characterization of foot posture: the Clarke angle. Third, we proposed a mathematical model to predict plantar pressure magnitude under the medial arch using body mass and the Clarke angle. Methods Sixty children with flatfoot and 33 aged-matched controls were recruited. Measurements included in-shoe plantar pressure distribution, ground reaction force, Clarke angle, and radiography assessment. The measured Clarke angle was compared with radiographic measurements, and its test-retest reliability was determined. A mathematical model was fitted to predict plantar pressure distribution under the medial arch using easy-to-measure variables (body mass and the Clarke angle). Results A high correlation was observed between the Clarke angle and radiography measurements (r > 0.9; P < 10−6). Excellent between- and within-day test-retest reliability for Clarke angle measurement (intraclass correlation coefficient, >0.9) was observed. Results also suggest that pressure magnitude under the medial arch can be estimated using the Clarke angle and body mass (R2 = 0.95; error, <0.04 N/cm2 [2%]). Conclusions This study suggests that the Clarke angle is a practical, reliable, and sensitive metric for quantification of medial arch height in children and could be recommended for research and clinical applications. It can also be used to estimate plantar pressure under the medial arch, which, in turn, may assist in the timely intervention and prognosis of prospective problems associated with flatfoot posture.
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McPoil, Thomas G., and Mark W. Cornwall. "Use of Plantar Contact Area to Predict Medial Longitudinal Arch Height During Walking." Journal of the American Podiatric Medical Association 96, no. 6 (November 1, 2006): 489–94. http://dx.doi.org/10.7547/0960489.
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A study was conducted to determine whether plantar surface contact area measures calculated from footprints collected during walking can be used to predict the height of the medial longitudinal arch. Thirty healthy women participated in the study. Arch height was determined by the distance from the navicular tuberosity to the floor and by the “bony” arch index. Dynamic plantar surface contact area was recorded using a pressure platform as the subjects walked across a 12-m walkway. The arch index and the total plantar surface contact area were determined from the pressure sensor data. The results indicated that plantar surface contact area could be used to estimate only approximately 27% of the height of the medial longitudinal arch as determined by navicular tuberosity height and the bony arch index. These findings demonstrate the inability of the clinician to predict the vertical height of the medial longitudinal arch on the basis of the amount of foot plantar surface area in contact with the ground during walking. (J Am Podiatr Med Assoc 96(6): 489-494, 2006)
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Munch, P. A., and A. M. Brown. "Role of vessel wall in acute resetting of aortic baroreceptors." American Journal of Physiology-Heart and Circulatory Physiology 248, no. 6 (June 1, 1985): H843—H852. http://dx.doi.org/10.1152/ajpheart.1985.248.6.h843.
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Previously we found that baroreceptor (BR) pressure-frequency (PF) curves rapidly (5 min) reset to changes in mean arterial pressure (MAP) exclusive of sympathetic efferents or circulating hormones. Since BRs are mechanically coupled to vessel wall structures, resetting may be due to changes in the wall. This was examined using an in vitro rat aortic arch-aortic nerve preparation and a photoelectric device to measure arch diameter. Pressure-diameter (PD) curves were constructed at selected MAPs following the resetting protocol used previously [Am. J. Physiol. 244 (Heart Circ. Physiol. 13): H672-H680, 1983]. Overall there was no consistent relationship between the PD curves and MAP, which was in sharp contrast to BR PF resetting. To determine if smooth muscle tone could affect aortic or BR function, the arch was constricted or relaxed with norepinephrine (NE) or sodium nitroprusside (NP), respectively. BR PF and aortic PD curves were constructed before and after drug treatment. NE reduced and NP increased discharge at given pressures. Diameter-frequency (DF) plots were not altered by either drug. PD and PF curves at constant MAP were stable after the initial responses to NP relaxation were completed. Subsequent MAP elevations in NP reset BRs to higher pressures, whereas PD curves shifted to lower pressures. Hence, DF plots shifted to higher diameters. These results show that neither smooth muscle activity nor mechanical changes in the whole wall can account for BR rapid resetting. The process probably occurs in the receptors.
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Liu, Shu Zhi. "Simplified Calculation Method of Optimal Centre Line of the Arch." Advanced Materials Research 446-449 (January 2012): 611–14. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.611.
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Studied the arch structure under vertical loads reasonable arch axis problem, regardless of the arch on the role of distributed load or concentrated load, the structure can be simplified into line arch, ignoring axial deformation of bars, the moments at the joints must be equal to zero, the ratio of rise to span for the parameters, derived function of the coordinates of each node to determine the arch of the pressure line, and also determine the horizontal thrusts of the arch. The method is simple and practical, especially for the preliminary design stage, for the arch axis provides the basis for further optimization.
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Munch, P. A., and J. C. Longhurst. "Contrasting effects of vasopressin and angiotensin II on rabbit aortic baroreceptors." American Journal of Physiology-Heart and Circulatory Physiology 260, no. 3 (March 1, 1991): H811—H820. http://dx.doi.org/10.1152/ajpheart.1991.260.3.h811.
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Arginine vasopressin (AVP) reportedly enhances, whereas angiotensin II (ANG II) attenuates, baroreflex control of the circulation. Here we examine whether these responses can be attributed, in part, to local actions on myelinated baroreceptor (BR) afferents, either directly or via changes in vascular tone. An in vitro rabbit aortic arch/aortic nerve preparation was used to study regularly discharging presumably myelinated BRs under controlled static and pulsatile pressures. At constant suprathreshold pressures, AVP (10(-13) M to 10(-6) M) had no effect on arch diameter or BR frequency, whereas equimolar concentrations of ANG II evoked dose-dependent vasoconstriction and associated BR inhibition. Differences were not caused by limited diffusion to BR endings lying outside the media, since similar results were obtained with either luminal or adventitial applications. AVP also had no effect on diameter or discharge in arches preconstricted with norepinephrine, whereas acetylcholine (ACh) relaxed the arch and thereby increased BR activity. These results eliminate possible AVP-induced endothelium-dependent vasodilation or potentiation of adrenergic vasoconstriction that would not be evident in isolated arches lacking tone. Finally, AVP did not sensitize BRs to changes in pressure, since ramp-evoked pressure-discharge curves remained constant and pulsatile discharge in response to sine-wave pressure inputs was unaltered. ANG II, however, shifted pressure-discharge curves to higher pressures and, with pulsatile inputs at constant mean pressure, reduced peak and average discharge firing rates. In conclusion, AVP has no apparent peripheral effect on aortic myelinated BRs in rabbits that could contribute to amplification of the baroreflex when AVP levels are elevated. In contrast, ANG II can inhibit BR firing as a consequence of local vasoconstriction, which may contribute to attenuation of the reflex when ANG II levels are elevated.
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Mochizuki, Yasuaki, Katsuyuki Hoshina, Kunihiro Shigematsu, Tetsuro Miyata, and Toshiaki Watanabe. "Distal bypass to a critically ischemic foot increases the skin perfusion pressure at the opposite site of the distal anastomosis." Vascular 24, no. 4 (July 10, 2016): 361–67. http://dx.doi.org/10.1177/1708538115597605.
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Introduction The purpose of the study was to reveal the effect of blood flow supply to the foot by analyzing the skin perfusion pressure values and the pedal arch connection after bypass surgery. Patients and methods We selected 48 operated limbs whose skin perfusion pressure was measured pre- and post-operatively on the opposite site of distal anastomosis. We also assigned the ischemic limbs to three groups according to the patency of the pedal arch: good, intermediate, and poor. Results The mean value of skin perfusion pressure increased significantly from 27.0 ± 14.9 to 52.8 ± 16.0 ( p < 0.001) post-operatively. Skin perfusion pressure improved in most of the limbs post-operatively and decreased or unchanged in only four limbs, all of which showed improved tissue loss. Three amputated limbs were due to infection, and all showed an increase in skin perfusion pressure. Conclusion It was difficult to correlate limb prognosis to skin perfusion pressure and the pedal arch connection.
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Kim, Daekyoo, Cara L. Lewis, and Simone V. Gill. "Effects of obesity and foot arch height on gait mechanics: A cross-sectional study." PLOS ONE 16, no. 11 (November 29, 2021): e0260398. http://dx.doi.org/10.1371/journal.pone.0260398.
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Foot arch structure contributes to lower-limb joint mechanics and gait in adults with obesity. However, it is not well-known if excessive weight and arch height together affect gait mechanics compared to the effects of excessive weight and arch height alone. The purpose of this study was to determine the influences of arch height and obesity on gait mechanics in adults. In this study, 1) dynamic plantar pressure, 2) spatiotemporal gait parameters, 3) foot progression angle, and 4) ankle and knee joint angles and moments were collected in adults with normal weight with normal arch heights (n = 11), normal weight with lower arch heights (n = 10), obesity with normal arch heights (n = 8), and obesity with lower arch heights (n = 18) as they walked at their preferred speed and at a pedestrian standard walking speed, 1.25 m/s. Digital foot pressure data were used to compute a measure of arch height, the Chippaux-Smirak Index (CSI). Our results revealed that BMI and arch height were each associated with particular measures of ankle and knee joint mechanics during walking in healthy young adults: (i) a higher BMI with greater peak internal ankle plantar-flexion moment and (ii) a lower arch height with greater peak internal ankle eversion and abduction moments and peak internal knee abduction moment (i.e., external knee adduction moment). Our results have implications for understanding the role of arch height in reducing musculoskeletal injury risks, improving gait, and increasing physical activity for people living with obesity.
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Gill, Simone V., Cara L. Lewis, and Jeremy M. DeSilva. "Arch Height Mediation of Obesity-Related Walking in Adults: Contributors to Physical Activity Limitations." Physiology Journal 2014 (December 16, 2014): 1–8. http://dx.doi.org/10.1155/2014/821482.
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Walking and foot arch structure have risk-increasing effects that contribute to decreased physical activity in adults with overweight and obese body mass index (BMI) scores. However, it is unknown whether both excessive weight and arch height influence walking compared to the effects of excessive weight or arch height alone. The purpose of this study was to investigate if arch height mediates obesity-related walking characteristics among adults with different BMI classifications. Spatiotemporal walking kinematics and dynamic plantar pressure were collected as adults with normal (n=30), overweight (n=34), and obese (n=25) BMI scores walked at their preferred speed. Digital footprints created with plantar pressure data were used to calculate a measure of arch height, the Chippaux-Smirak Index (CSI). The results showed that obese adults had lower arches than normal weight adults (P<0.05). Arch height was related to velocity, double limb support time, stance time, step length, and foot rotation (all Ps < 0.05). Overweight participants with lower arches had lower velocities and higher double limb support times (all Ps < 0.05). The results have implications for aiding an increase in physical activity for overweight adults via intervening in adults’ arch height.
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Kim, Daekyoo, and Daekyoo Kim. "Foot arch height affects the effect of BMI on gait and lower-limb joint kinematics." IJASS(International Journal of Applied Sports Sciences) 32, no. 2 (December 31, 2020): 95–104. http://dx.doi.org/10.24985/ijass.2020.32.2.95.
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Foot arch structure contributes to walking in adults with obesity. However, little is known about the relationship between arch height and walking in these populations. The purpose of this study was to investigate if arch height affects gait characteristics among adults classified into three groups by body mass index (BMI). In this study, dynamic plantar pressure, spatiotemporal gait parameters, and lower-limb joint kinematics were collected from adults with normal weight (n=21), moderate obesity (n=18), and severe obesity (n=8) during walking at their preferred speed. Digital foot pressure data were used to compute a measure of arch height, the Chippaux-Smirak Index (CSI). Our results revealed that adults with higher BMI scores had lower arches than adults with lower BMI scores (p<0.01). Arch height was related to step width, double-limb support time, knee joint extension angle, and knee joint abduction angle (ps<0.01). Our results have implications for improving gait stability and increasing physical activity for obese populations via intervening in arch height.
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Laín, Santiago, and Andres D. Caballero. "Simulation of unsteady blood flow dynamics in the thoracic aorta." Ingeniería e Investigación 37, no. 3 (September 1, 2017): 92–101. http://dx.doi.org/10.15446/ing.investig.v37n3.59761.
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In this work, blood flow dynamics was analyzed in a realistic thoracic aorta (TA) model under unsteady-state conditions via velocity contours, secondary flow, pressure and wall shear stress (WSS) distributions. Our results demonstrated that the primary flow velocity is skewed towards the inner wall of the ascending aorta; but this skewness shifts towards the posterior wall in the aortic arch and then towards the anterior-outer wall in the descending aorta. Within the three arch branches, the flow velocity is skewed to the distal walls with flow reversal along the proximal walls. Strong secondary flow motion is observed in the TA, especially at the inlet of the arch branches. WSS is highly dynamic, but was found to be the lowest along the proximal walls of the arch branches. Finally, pressure was found to be low along the inner aortic wall and in the proximal walls of the arch branches, and high around the three stagnation regions distal to the arch branches and along the outer wall of the ascending aorta.
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Wisotzkey, Bethany L., Christoph P. Hornik, Amanda S. Green, and Piers C. A. Barker. "Comparison of invasive and non-invasive pressure gradients in aortic arch obstruction." Cardiology in the Young 25, no. 7 (January 20, 2015): 1348–57. http://dx.doi.org/10.1017/s1047951114002522.
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AbstractBackgroundAortic arch obstruction can be evaluated by catheter peak-to-peak gradient or by Doppler peak instantaneous pressure gradient. Previous studies have shown moderate correlation in discrete coarctation, but few have assessed correlation in patients with more complex aortic reconstruction.MethodsWe carried out retrospective comparison of cardiac catheterisations and pre- and post-catheterisation echocardiograms in 60 patients with native/recurrent coarctation or aortic reconstruction. Aortic arch obstruction was defined as peak-to-peak gradient ⩾25 mmHg in patients with native/recurrent coarctation and ⩾10 mmHg in aortic reconstruction.ResultsDiastolic continuation of flow was not associated with aortic arch obstruction in either group. Doppler peak instantaneous pressure gradient, with and without the expanded Bernoulli equation, weakly correlated with peak-to-peak gradient even in patients with a normal cardiac index (r=0.36, p=0.016, and r=0.49, p=0.001, respectively). Receiver operating characteristic curve analysis identified an area under the curve of 0.61 for patients with all types of obstruction, with a cut-off point of 45 mmHg correctly classifying 64% of patients with arch obstruction (sensitivity 39%, specificity 89%). In patients with aortic arch reconstruction who had a cardiac index ⩾3 L/min/m2, a cut-off point of 23 mmHg correctly classified 69% of patients (71% sensitivity, 50% specificity) with an area under the curve of 0.82.ConclusionThe non-invasive assessment of aortic obstruction remains challenging. The greatest correlation of Doppler indices was noted in patients with aortic reconstruction and a normal cardiac index.
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Wang, Yu, Yaan Hu, Jinde Gu, Yu Peng, and Yang Xue. "Impact pressure distribution of inverted arch plunge pool for large discharge." Water Supply 20, no. 1 (November 1, 2019): 209–18. http://dx.doi.org/10.2166/ws.2019.157.
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Abstract In view of high water head and large discharge in the release structures of hydraulic projects, the inverted arch plunge pool has been put forward due to higher overload capability and stability. Impact pressure on the bottom is a serious concern in design safety precautions, however, the quantitative impact pressure distribution in the inverted arch plunge pool is not yet elucidated. In this study, a novel approach is presented to estimate the impact pressure of an inverted arch plunge pool. Impact pressure characteristics are experimentally investigated under different hydraulic conditions. The results detailed the effect of relative discharge coefficient and the deflection angle relative to the vertical central axis of the plunge pool bottom. The predicting formulas of impact pressure distribution are derived within small relative errors, and the proposed approaches have good applicability in three case studies. The achievements of this investigation are used to define issuance parameters relevant for engineering practice.
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Imhauser, Carl W., Nicholas A. Abidi, David Z. Frankel, Kenneth Gavin, and Sorin Siegler. "Biomechanical Evaluation of the Efficacy of External Stabilizers in the Conservative Treatment of Acquired Flatfoot Deformity." Foot & Ankle International 23, no. 8 (August 2002): 727–37. http://dx.doi.org/10.1177/107110070202300809.
Full textAbstract:
This study quantified and compared the efficacy of in-shoe orthoses and ankle braces in stabilizing the hindfoot and medial longitudinal arch in a cadaveric model of acquired flexible flatfoot deformity. This was addressed by combining measurement of hindfoot and arch kinematics with plantar pressure distribution, produced in response to axial loads simulating quiet standing. Experiments were conducted on six fresh-frozen cadaveric lower limbs. Three conditions were tested: intact-unbraced; flatfoot-unbraced; and flatfoot-braced. Flatfoot deformity was created by sectioning the main support structures of the medial longitudinal arch. Six different braces were tested including two in-shoe orthoses, three ankle braces and one molded ankle-foot orthosis. Our model of flexible flatfoot deformity caused the calcaneus to evert, the talus to plantarflex and the height of the talus and medial cuneiform to decrease. Flexible flatfoot deformity caused a pattern of medial shift in plantar pressure distribution, but minimal change in the location of the center of pressure. Furthermore, in-shoe orthoses stabilized both the hindfoot and the medial longitudinal arch, while ankle braces did not. Semi-rigid foot and ankle orthoses acted to stabilize the medial longitudinal arch. Based on these results, it was concluded that treatment of flatfoot deformity should at least include use of in-shoe orthoses to partially restore the arch and stabilize the hindfoot.
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Molloy, Joseph M., Douglas S. Christie, Deydre S. Teyhen, Nancy S. Yeykal, Bradley S. Tragord, Matthew S. Neal, Eric S. Nelson, and Thomas McPoil. "Effect of Running Shoe Type on the Distribution and Magnitude of Plantar Pressures in Individuals with Low- or High-Arched Feet." Journal of the American Podiatric Medical Association 99, no. 4 (July 1, 2009): 330–38. http://dx.doi.org/10.7547/0980330.
Full textAbstract:
Background: Research addressing the effect of running shoe type on the low- or high-arched foot during gait is limited. We sought 1) to analyze mean plantar pressure and mean contact area differences between low- and high-arched feet across three test conditions, 2) to determine which regions of the foot (rearfoot, midfoot, and forefoot) contributed to potential differences in mean plantar pressure and mean contact area, and 3) to determine the association between the static arch height index and the dynamic modified arch index. Methods: Plantar pressure distributions for 75 participants (40 low arched and 35 high arched) were analyzed across three conditions (nonshod, motion control running shoes, and cushioning running shoes) during treadmill walking. Results: In the motion control and cushioning shoe conditions, mean plantar contact area increased in the midfoot (28% for low arched and 68% for high arched), whereas mean plantar pressure decreased by approximately 30% relative to the nonshod condition. There was moderate to good negative correlation between the arch height index and the modified arch index. Conclusions: Cushioning and motion control running shoes tend to increase midfoot mean plantar contact area while decreasing mean plantar pressure across the low- or high-arched foot. (J Am Podiatr Med Assoc 99(4): 330–338, 2009)