scholarly journals The evolution of pelvic canal shape and rotational birth in humans

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Ekaterina Stansfield ◽  
Barbara Fischer ◽  
Nicole D. S. Grunstra ◽  
Maria Villa Pouca ◽  
Philipp Mitteroecker
Keyword(s):  
Pelvic Floor ◽  
Complex Shape ◽  
Upright Posture ◽  
Birth Canal ◽  
Abdominal Organs ◽  
Pelvic Inlet ◽  
Deformation Stress ◽  
The Stability ◽  
Floor Stability ◽  
Oval Shape

Abstract Background The human foetus typically needs to rotate when passing through the tight birth canal because of the complex shape of the pelvis. In most women, the upper part, or inlet, of the birth canal has a round or mediolaterally oval shape, which is considered ideal for parturition, but it is unknown why the lower part of the birth canal has a pronounced anteroposteriorly oval shape. Results Here, we show that the shape of the lower birth canal affects the ability of the pelvic floor to resist the pressure exerted by the abdominal organs and the foetus. Based on a series of finite element analyses, we found that the highest deformation, stress, and strain occur in pelvic floors with a circular or mediolaterally oval shape, whereas an anteroposterior elongation increases pelvic floor stability. Conclusions This suggests that the anteroposterior oval outlet shape is an evolutionary adaptation for pelvic floor support. For the pelvic inlet, by contrast, it has long been assumed that the mediolateral dimension is constrained by the efficiency of upright locomotion. But we argue that the mediolateral elongation has evolved because of the limits on the anteroposterior diameter imposed by upright posture. We show that an anteroposteriorly deeper inlet would require greater pelvic tilt and lumbar lordosis, which compromises spine health and the stability of upright posture. These different requirements of the pelvic inlet and outlet likely have led to the complex shape of the pelvic canal and to the evolution of rotational birth characteristic of humans.

scholarly journals The evolution of pelvic canal shape and rotational birth in humans

2021 ◽  
Author(s):  
Ekaterina Stansfield ◽  
Barbara Fischer ◽  
Philipp Mitteroecker
Keyword(s):  
Pelvic Floor ◽  
Complex Shape ◽  
Birth Canal ◽  
Abdominal Organs ◽  
Pelvic Inlet ◽  
Deformation Stress ◽  
The Stability ◽  
Floor Stability ◽  
Pelvic Floor Support ◽  
Oval Shape

Abstract The human foetus needs to rotate when passing through the tight birth canal because of the complex shape of the pelvis. In most women the upper part, or inlet, of the birth canal has a round or mediolaterally oval shape, which is considered ideal for parturition, but it is unknown why the lower part, or outlet, of the birth canal has a pronounced anteroposteriorly oval shape. Here we show that the shape of the lower birth canal affects the ability of the pelvic floor to resist pressure exerted by the abdominal organs and the foetus. Based on a series of finite element analyses, we found that the highest deformation, stress and strain occur in pelvic floors with a circular or mediolaterally oval shape, whereas an anteroposterior elongation increases pelvic floor stability. This suggests that the anteroposterior oval outlet shape is an evolutionary adaptation for pelvic floor support. For the pelvic inlet, by contrast, it has long been assumed that the mediolateral dimension is constrained by the efficiency of upright locomotion. But we argue that upright stance limits the anteroposterior dimension of the inlet. A deeper inlet requires greater pelvic tilt and lumbar lordosis, which compromises spine health and the stability of upright posture. These different requirements on the pelvic inlet and outlet have led to the complex shape of the human pelvic canal and to the evolution of rotational birth.

scholarly journals HUBUNGAN PARITAS DENGAN DERAJAT LASERASI JALAN LAHIR DI POLINDES JETIS LOR KECAMATAN NAWANGAN KABUPATEN PACITAN

2019 ◽  
Vol 6 (1) ◽  
pp. 48-53
Author(s):  
Etika Desi Yogi
Keyword(s):  
Correlation Analysis ◽  
Pelvic Floor ◽  
Vaginal Wall ◽  
Labor Process ◽  
Birth Process ◽  
Birth Canal ◽  
Calculation Results ◽  
Independent Variable ◽  
Relationship Of ◽  
The Relationship

For women, the perineum is very important stretching and lubricating the perineum during labor can weaken the pelvic floor muscles in the vaginal wall, trauma to the perineum also causes discomfort and pain during sexual intercourse and an estimated 85% of maternal mothers experience birth canal lacerations (Kettle and Tohil 2008). One of the fears that are often felt by pregnant women, especially third timers, is fear of being torn and afraid of sewing. Especially for mothers who have experienced it, this can make their own trauma when facing the birth process later (USU, 2006). The purpose of this study was to determine the relationship of parity to the degree of laceration of the birth pathway in Jetis Lor Polindes, Nawangan District, Pacitan Regency. The design or design in this study is correlation analysis, with the "retrospective" approach. This study analyzed the relationship of parity with the degree of laceration of the birth path in Jetis Lor Polindes, Nawangan District, Pacitan Regency. In this study, the population was all mothers giving birth at Jetis Lor Polindes, Nawangan District, Pacitan Regency. The samples in this study were all mothers giving birth at Jetis Lor Polindes, Nawangan District, Pacitan Regency. In this study by looking at the last 1 year data. In this study the independent variable is parity. In this study the dependent variable is the degree of laceration of the birth canal. Based on the calculation results of SPSS 11.5 for Windows, it was found that there was no relationship between parity and laceration degrees in the Jetis Lor Polindes, Nawangan Subdistrict, Pacitan Regency, from the results of probability (sig. 2-tailed) 0.22 <0.05.The researcher hopes that the mother will seek information and increase knowledge about the labor process, so that with good knowledge will reduce lacerations on the birth canal

scholarly journals Two-stage magnetic-elasto-pulse stamping of thin sheet parts

2021 ◽  
Vol 2131 (4) ◽  
pp. 042057
Author(s):  
S Nescoromniy ◽  
E Strizhakov ◽  
D Minko
Keyword(s):  
Static Loading ◽  
Complex Shape ◽  
Static Load ◽  
Thin Sheet ◽  
Relative Deformation ◽  
Capacitive Storage ◽  
Elastic Punch ◽  
The Stability ◽  
Processing Zone ◽  
Forging Force

Abstract The article substantiates the use of preliminary static loading and subsequent forging force when stamping thin sheet parts of complex shape with an elastic punch. The static load provides a relative deformation of the order of 20– 30% in the processing zone, which guarantees the stability of the position of the workpiece during subsequent pulsed loading. This technique is very important in the manufacture of asymmetric parts with a thickness of 0.01 – 0.3 mm. As a result, the accuracy of the products obtained corresponds to the 7th grade.The article provides a schematic diagram and a description of the proposed design of a double-action press, and analyzes the cyclogram of the device.It is recommended to carry out a static load with an electric drive, a pulsed one with a magnetic hammer, which is connected to a generator of impulse currents with a capacitive storage with an energy capacity of up to 40 kJ with a natural discharge frequency of the current of 20 kHz.

Microphotometric Characterization of Fluid Segment Populations Generated in Different Simple Microfluidic Networks

2006 ◽  
Author(s):  
J. M. Ko¨hler ◽  
P. A. Groß
Keyword(s):  
Flow Rate ◽  
Free Fluid ◽  
Flow Conditions ◽  
Carrier Liquid ◽  
Fluid Network ◽  
On Line ◽  
Deformation Stress ◽  
The Stability ◽  
Rate Ratios

The stability of fluid segments is limited by deformation stress and by coalescence events. Both factors are typical for the passage of fluid segments through micro fluidic networks. Therefore, the coalescence behaviour of micro fluid segments in simple net work structures in dependence of flow rate ratios was investigated and characterized by the composition of obtained segment populations. Series of segments of different size and distance were generated either in a double T- or in a triple T-arrangement. PTFE elements were used for the micro fluid network. Nearly pulsation-free fluid actuation was realized by syringe pumps. The flow conditions in the input streams of carrier liquid and injected solutions remained constant during the experiments. Segment sequences become divers by different injection, stacking and coalescence events. The resulting segment sequences were characterized by on-line micro photometry. The populations of obtained micro fluid segments during each experiment were characterized by the distribution of segment size and segment distance or segment periode, respectively. Simulations support the assumption, that the character of segment populations is mainly determined by the flow rate ratios and by the coalescence sensitivity beside the topology of the fluidic network.

scholarly journals Task-specific differences in respiration-related activation of deep and superficial pelvic floor muscles

2019 ◽  
Vol 126 (5) ◽  
pp. 1343-1351 ◽  
Author(s):  
Rafeef Aljuraifani ◽  
Ryan E. Stafford ◽  
Leanne M. Hall ◽  
Wolbert van den Hoorn ◽  
Paul W. Hodges
Keyword(s):  
Pelvic Floor ◽  
Deep Layer ◽  
Pelvic Floor Dysfunction ◽  
Muscle Layer ◽  
Superficial Layer ◽  
Pelvic Floor Muscles ◽  
Abdominal Pressure ◽  
Quiet Breathing ◽  
Abdominal Organs ◽  
Deep Layers

The female pelvic floor muscles (PFM) are arranged in distinct superficial and deep layers that function to support the pelvic/abdominal organs and maintain continence, but with some potential differences in function. Although general recordings of PFM activity show amplitude modulation in conjunction with fluctuation in intra-abdominal pressure such as that associated with respiration, it is unclear whether the activities of the two PFM layers modulate in a similar manner. This study aimed to investigate the activation of the deep and superficial PFM during a range of respiratory tasks in different postures. Twelve women without pelvic floor dysfunction participated. A custom-built surface electromyography (EMG) electrode was used to record the activation of the superficial and deep PFM during quiet breathing, breathing with increased dead space, coughing, and maximal and submaximal inspiratory and expiratory efforts. As breathing demand increased, the deep PFM layer EMG had greater coherence with respiratory airflow at the frequency of respiration than the superficial PFM ( P = 0.038). During cough, the superficial PFM activated earlier than the deep PFM in the sitting position ( P = 0.043). In contrast, during maximal and submaximal inspiratory and expiratory efforts, the superficial PFM EMG was greater than that for the deep PFM ( P = 0.011). These data show that both layers of PFM are activated during both inspiration and expiration, but with a bias to greater activation in expiratory tasks/phases. Activation of the deep and superficial PFM layers differed in most of the respiratory tasks, but there was no consistent bias to one muscle layer.NEW & NOTEWORTHY Although pelvic floor muscles are generally considered as a single entity, deep and superficial layers have different anatomies and biomechanics. Here we show task-specific differences in recruitment between layers during respiratory tasks in women. The deep layer was more tightly modulated with respiration than the superficial layer, but activation of the superficial layer was greater during maximal/submaximal occluded respiratory efforts and earlier during cough. These data highlight tightly coordinated recruitment of discrete pelvic floor muscles for respiration.

scholarly journals Stable Balance Adjustment Structure of the Quadruped Robot Based on the Bionic Lateral Swing Posture

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Jian-Hua Qin ◽  
Jie Luo ◽  
Kai-Chi Chuang ◽  
Tian-Syung Lan ◽  
Lie-Ping Zhang ◽  
...  
Keyword(s):  
Static Stability ◽  
Quadruped Robot ◽  
Experimental Simulation ◽  
Upright Posture ◽  
Design And Optimization ◽  
Generalized Coordinates ◽  
The Stability ◽  
Leg Kinematics ◽  
Peak Value ◽  
Robot Body

Aiming at the problem that the stability of the quadruped robot is decreased as its leg momentum is too high, a stable balance adjustment structure of the quadruped robot based on the bionic lateral swing posture is proposed. First, the leg structure of the quadruped robot is improved and designed by using the mechanism of the lateral swing posture of the leg of the hoof animal. Then, the D-H method is used to construct the corresponding leg kinematics model and determine the generalized coordinates of the leg joints in the lateral swing posture. The torque expression of the quadruped robot when it is tilted is established. Based on the differential equation of momentum of the hip joint and its static stability analysis, the static stability conditions in the upright posture and the bionic lateral swing posture are given. Finally, the experimental simulation and comparative analysis of the upright posture and the lateral swing posture of the quadruped robot are proposed by using the Adams virtual prototype technology. The simulation results show that as the angle of lateral swing increases, the peak value of the positive flip torque of the quadruped robot body increases accordingly, while the degree of tilt decreases accordingly, which shows that the bionic lateral swing posture of the quadruped robot has higher static stability than the traditional upright posture. This research provides a technical reference for the design and optimization of the offline continuous gait of the robot and the improvement of stability.

A Study on Stability of Expressway Tunnel Surrounding Rock Containing Weak Intercalated Rock

2010 ◽  
Vol 168-170 ◽  
pp. 2543-2547
Author(s):  
Da Kun Shi ◽  
Yang Song Zhang
Keyword(s):  
Rock Mass ◽  
Plastic Zone ◽  
Surrounding Rock ◽  
Constitutive Law ◽  
Numerical Tests ◽  
Stability Of Surrounding Rock ◽  
Strain Type ◽  
Deformation Stress ◽  
Plain Strain ◽  
The Stability

Weak intercalated rock plays an important role in the stability of engineering rock mass. It controls the mechanism of deformation and breakage of rocks. Systematic numerical tests have been carried out to study the stability of surrounding rock mass with different distributions of weak intercalated rock has been analyzed by the FEM software ABAQUS. All of the numerical modelings are plain-strain type with elasto-plastic constitutive law and Drucker-Prager failure criterion. Some quantificational results about the influence of weak intercalated rock are summarized, especially the influence on the deformation, stress of surrounding rocks and plastic zone. Because of weak intercalated rock, the stress of surrounding rock appears the character of discontinuity. In addition, the distribution of plastic zone is also affected. When weak intercalated rocks exist in vault, spandrel and bottom, the situation of surrounding rock is comparatively unfavorable. These results have a certain role in guiding significance to the site selection and layout, the majorization of supporting system and the construction of tunnel of the same kind.

Comparative Analysis of Hard Anodized Layer on Aluminium Alloy

2014 ◽  
Vol 782 ◽  
pp. 615-618
Author(s):  
Lenka Klakurková ◽  
Eduard Hégr ◽  
Ladislav Čelko ◽  
Tomáš Podrábský ◽  
Martin Juliš ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Comparative Analysis ◽  
Aluminium Alloy ◽  
Complex Shape ◽  
Water Solution ◽  
Vacuum Pump ◽  
Demineralized Water ◽  
The Stability ◽  
Acid Water Solution ◽  
Scanning Electron

Hard anodized layers were produced by two different manufacturers on the same type of aluminium alloy on a vacuum pump part of complex shape. The sulphuric acid/water solution was used to produce alumina layers, which were subsequently sealed in demineralized water. A comparative analysis based on metallographic methodology, with the aim to control the stability of alumina formation process and to identify its defects, was performed by means of light and scanning electron microscopy, surface profilometry and microhardness measurements. To determine the thickness of alumina layers, the image analysis was also used.

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