Abstract 13048: A Simple Model to Describe the Relationship Between Compression Force and Depth During CPR

Aim: The relationship between force and depth during manual chest compressions depends on the patient and on the dynamics with which the rescuer applies the force. Force-depth models with many fitting parameters have been proposed making physical interpretation complicated. The aim of this work was to design a simpler force-depth model, accommodating anticipated differences in compression and recoil phases. Materials and Methods: Force and acceleration signals were extracted from out-of-hospital-cardiac arrest (OHCA) defibrillator recordings (TVF&R, OR, USA), equipped with CPR technology. Compression depth and velocity signals were computed from acceleration. We analyzed intervals of 20-s within the 1st min of chest compressions. Our model decomposes the applied force as the sum of an elastic and a damped term, considering different damping coefficients for the compression and recoil phases. Coefficient of elasticity was calculated at the instant of maximum compression depth (null velocity) and damping coefficients at the instants of maximum compression and recoil velocities. The estimated depth signal is shown in the figure. The goodness of the model was assessed through the determination coefficient R 2 . Results: We analyzed 1,074 compressions from 30 OHCA recordings. Median (IQR) compression depth was 4.6 (4.0-5.4) cm; compression rate was 107 (102–113) cpm; coefficient of elasticity was 100.67 (78.95–125.01) N/cm; compression damping coefficient was 2.57 (1.84–3.29) N/(cm/s) and recoil damping coefficient was 3.59 (2.58–4.90) N/(cm/s). Median R 2 was 0.993 (0.984–0.996). Conclusions: This model, derived using fewer parameters, could help with the interpretation of the mechanical properties of the chest during CPR. It may also be useful for the assessment of inter-patient differences with age, sex, and body constitution, as well as of the evolution of elasticity and damping of patient’s chest during the course of resuscitation.

The results of sphincterometry in patients after sorgion treatment of extrasphintery anal fistula

More than 30% of patients with chronic paraproctitis have complex forms. They are most often complicated by external sphincter insufficiency due to deformation of the anal canal and scarring of the sphincters. The main principle of substantiation of surgical treatment of extrasphincteric pararectal fistulas is the individual choice of method in each particular patient. It is based on a comprehensive assessment of such factors as the etiology of the fistula, its distance from the edge of the anus, the relationship of the defect or fistula with the sphincter muscles apparatus, the severity of the scarring process, the functional state of the rectum. Aim. Evaluation of the functional state of the sphincter apparatus of the rectum in patients with extrasphincteric pararectal fistulas in the preoperative, early and late postoperative periods. Materials and methods. To determine the average indicators of anal sphincter function, basal tone and maximal compression force were measured using a sphincterometer "Sphinctometer STM-0164-SM" in 114 healthy individuals (68 men and 46 women) of different ages (16 to 80 years) who objectively had no signs of anal incontinence. In all patients, sphincterometry was preceded by a thorough proctological examination, and proctological pathology was excluded. Therefore, hemorrhoids or anal fissures, which lead to increased basal tone at rest, were excluded so as not to lead to falsified values. Results. Indicators of the maximum compression force in the early postoperative period, ie the compression force of the external anal sphincter, in both groups were significantly lower than preoperative and ranged from 55 to 154 mm Hg, respectively. and from 63 to 137 mm Hg. This can be explained by the presence of a granulating wound in the pararectal tissue, edema and partial injury of the external anal sphincter during surgery. In the late postoperative period, 6-12 months after surgery, the indicators of basal tone in both groups approached the preoperative indicators. In the main group, the study was performed in 22 patients. In these 22 patients, the tone of the internal anal sphincter did not differ significantly from the preoperative and ranged from 20 to 37 mm Hg. In the control group, in all 32 patients, the basal tone of the anal sphincter was significantly lower than before surgery - from 17 to 28 mm Hg. There were no clinical manifestations of incontinence at rest in either main or control groups. In the late postoperative period in both groups a decrease in the maximum compression force of the external anal sphincter was revealed. In the main group the maximum compression force of the external anal sphincter varied from 71 to 186 mm Hg, and in the control group from 77 to 135 mm Hg, respectively. Conclusion. Surgical treatment of patients with extrasphincteric pararectal fistulas significantly reduces the contractile function of the external anal sphincter in the postoperative period, regardless of the choice of surgery.

Designing of Steel CHS Columns Showing Maximum Compression Resistance

The paper deals with a shape optimisation procedure of steel, compressed bars. Circular hollow sections (CHS) of variable cross sections and variable wall thickness are taken into account. The proposed procedure for designing of steel rods exhibiting maximum compression resistance is effective and possible to use in engineering practice. The advantage of the proposed shape of the bar is that it allows to increase the value of its load carrying capacity, i.e. it ensures the transfer of a higher value of compressive force than similar, solid struts of the same mass and length. The extent of the increase in the load capacity relative to the load capacity of the reference solid, cylindrical bar depends on the slenderness of the reference bar and ranges from 60% to 170%. Due to this very beneficial fact, it can be used wherever it is required to maintain a certain stiffness and an increased value of compressive force is desired, as well as in constructions where it is necessary to reduce weight while maintaining the adopted mechanical parameters, e.g. values of load bearing capacity. Final results achieved in the research were presented in the form of the flow chart allowing to design the compressed columns of optimum shape.

RECONSTRUCTION OF TECTONIC STRESSES ON THE SCHMIDT PENINSULA (SAKHALIN)

The article presents data on the stress state of the Schmidt Peninsula of Sakhalin Island, obtained as a result of field tectonophysical studies in 2020. The importance of studying the northern part of Sakhalin is due to the prospects of this region for the minerals search. The performed studies allowed us to establish differences in the geodynamic condition between the western and eastern coasts of the peninsula. In general, the conditions of horizontal shear (shear type of deformation) prevail among the types of stress state in the studied territory. On the east coast, there are many situations of horizontal extension, which are usually confined to the axial parts of anticlinal structures. The west coast is characterized by the stable orientation of the axis of maximum compression in the NW direction and its subhorizontal position. For the east coast, the direction of the reconstructed orientations of maximum compression is characterized by greater variability. According to the data of the reconstruction, the stress-and-strain state pattern of the Schmidt Peninsula has significant differences from the main territory of Sakhalin Island.

Modeling of the roller pressing of fibrous materials

The work is devoted to modeling the regularities of hydraulic pressure distribution and fluid removal from the fibrous material in the contact zone. It was found that the hydraulic pressure in the compression zone increases from zero at the initial point of contact to a maximum at the point of maximum compression of the fibrous material. The patterns of distribution of hydraulic pressure in the recovery zone depend on the length of the section, where the fluid moves from the layer of material to the elastic coatings. It was revealed that the amount of liquid removed at the beginning of the compression zone grows faster, then the growth rate is much lower, and at the end of the compression zone, the removed liquid is stabilized. The patterns of change in the removed fluid in the recovery zone depend on the angle, which determines the position of the point where the fluid changes direction.

Mechanical Effects of Lag Screw Retightening in a Simulated Hindfoot Arthrodesis Model

Background: Nonunion following hindfoot arthrodesis may be caused by failure to maintain compression at the arthrodesis site. The ability of lag screws, commonly used in arthrodesis, to maintain compression in hindfoot bones has not been well characterized. The aim of this work was to quantify the stress relaxation response of hindfoot bone with initial and repeated compression with a lag screw. Methods: Ten sets of 25-mm-diameter bone cylinders were cut from the talus and calcaneus in fresh-thawed cadaveric feet. A load cell was compressed between cylinders with an 8.0-mm partially threaded cannulated lag screw simulating arthrodesis. For 7 sets, screws were tightened by 3 quarter-turns, rested for 3 minutes, retightened 1 quarter-turn, and rested for 30 minutes. Three sets served as controls in which screws were not retightened. Results: Maximum compression after initial screw tightening and retightening averaged 275 and 337 N ( P = .07), respectively. Compression 3 minutes after initial screw tightening and retightening averaged 199 and 278 N ( P = .027), respectively. The compression recorded 3 minutes after screw retightening was an average of 40% higher than that recorded 3 minutes after initial tightening. The average compression 30 minutes after screw retightening was 255 N, a compression loss of 25% from the average maximum compression after retightening. Eighty percent of this compression loss happened in an average of 5.5 minutes. Conclusion: Hindfoot bones exhibit compression loss over time during simulated arthrodesis. Compression maintenance in bone is improved with screw retightening. Further work is needed to understand the mechanism of action and determine optimum time for recompression. Clinical Relevance: Retightening lag screws before wound closure may improve compression at the arthrodesis site and thereby decrease the chance of nonunion. Level of Evidence: N/A, laboratory experiment.

Fast electron transport dynamics and energy deposition in magnetized, imploded cylindrical plasma

Inertial confinement fusion approaches involve the creation of high-energy-density states through compression. High gain scenarios may be enabled by the beneficial heating from fast electrons produced with an intense laser and by energy containment with a high-strength magnetic field. Here, we report experimental measurements from a configuration integrating a magnetized, imploded cylindrical plasma and intense laser-driven electrons as well as multi-stage simulations that show fast electrons transport pathways at different times during the implosion and quantify their energy deposition contribution. The experiment consisted of a CH foam cylinder, inside an external coaxial magnetic field of 5 T, that was imploded using 36 OMEGA laser beams. Two-dimensional (2D) hydrodynamic modelling predicts the CH density reaches 9.0 g cm − 3 , the temperature reaches 920 eV and the external B-field is amplified at maximum compression to 580 T. At pre-determined times during the compression, the intense OMEGA EP laser irradiated one end of the cylinder to accelerate relativistic electrons into the dense imploded plasma providing additional heating. The relativistic electron beam generation was simulated using a 2D particle-in-cell (PIC) code. Finally, three-dimensional hybrid-PIC simulations calculated the electron propagation and energy deposition inside the target and revealed the roles the compressed and self-generated B-fields play in transport. During a time window before the maximum compression time, the self-generated B-field on the compression front confines the injected electrons inside the target, increasing the temperature through Joule heating. For a stronger B-field seed of 20 T, the electrons are predicted to be guided into the compressed target and provide additional collisional heating. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 2)’.

Expanded dataset of mechanical properties and observed phases of multi-principal element alloys

This data article presents a compilation of mechanical properties of 630 multi-principal element alloys (MPEAs). Built upon recently published MPEA databases, this article includes updated records from previous reviews (with minor error corrections) along with new data from articles that were published since 2019. The extracted properties include reported composition, processing method, microstructure, density, hardness, yield strength, ultimate tensile strength (or maximum compression strength), elongation (or maximum compression strain), and Young’s modulus. Additionally, descriptors (e.g. grain size) not included in previous reviews were also extracted for articles that reported them. The database is hosted and continually updated on an open data platform, Citrination. To promote interpretation, some data are graphically presented.