Pressure Transmission Research Articles

The Age–Stiffness Relationships of Elastic and Muscular Arteries in a Control Population and in End-Stage Renal Disease Patients

Arterial dysfunction is major risk factor for cardiovascular complications, and arterial stiffness is an independent risk factor in end-stage renal disease patients. As the distance from the heart increases, arterial stiffness (pulse wave velocity) becomes progressively more marked. This generates a centrifugal stiffness gradient, which leads to partial, continuous local wave reflections, which in turn attenuate the transmission of pulsatile pressure into the microcirculation, thus limiting the potentially deleterious outcomes both upstream (on the heart: left-ventricular hypertrophy and coronary perfusion) and downstream (on the renal and cerebral microcirculation: reduced glomerular filtration and impaired cognitive functions). The impact of arterial aging is greater on the aorta and central capacitive arteries, and it is characterized by a loss or reversal of the physiological stiffness gradient between central and peripheral arteries. Recently, however, in contrast to observations on the aorta, several studies have shown less pronounced, absent, or even negative associations between muscular peripheral arteries and age–stiffness relationships, which may be associated with a decrease in or reversal of the stiffness gradient. These findings point to a potential benefit of assessing the muscular peripheral arteries to predict the risk of cardiovascular disease and suggest that reversal of the stiffness gradient may be an independent risk factor for all-cause mortality.

Narrative review: evolution in device technology and advances in surgical techniques on AMS 800 device in the last 50 years.

The current AMS 800 artificial urinary sphincter (AUS) device is designed to simulate the function of the biological urinary sphincter to prevent urinary flow through mucosal coaptation, compression, and pressure transmission. The challenges in designing the AMS 800 device involve not only the mechanical operation of the artificial sphincter device but also producing a device that is effective, safe, and durable for patients in the long term. The following article provides a narrative review regarding the evolution and development of the AMS 800 devices over the years and evaluates the advances in surgical techniques relating to AMS 800 implantation. Available literature pertaining to the AMS 800 device was reviewed from the MEDLINE and EMBASE databases between 1 January 2000 to 31 December 2022. Emphasis is placed on key scientific publications including previous reviews and clinical guidelines relevant to AMS 800 device(s) and surgical techniques. From the engineering point of view, the current AMS 800 device is ingenious and has stood the test of time. The basic design of this modern AUS consists of 3 separate components namely a pressure regulating balloon (PRB), an inflatable cuff, and a control pump. Continued innovations in device design and technology, coupled with refinements in surgical techniques over the past 5 decades have ensured that the AMS 800 device is and remains the standard of care in male stress urinary incontinence. While the long-term AMS 800 efficacy, safety, and durability are well documented, it is not without its limitations and complications. Mechanical and non-mechanical complications can occur especially in high-risk populations (such as in radiated patients) despite strict adherence to surgical principles and manufacturer's guidelines. Continued innovations in device design, technology, and surgical techniques have ensured that the AMS 800 device is an effective and safe treatment for male stress urinary incontinence (SUI). Future directions in the treatment of male SUI likely reside in cellular regenerative therapy and nanotechnology to restore, replace, or simulate the damaged native urinary sphincter.

Digital redesign of hypertension management with practice and patient apps for blood pressure control (PIA study): A cluster-randomised controlled trial in general practices.

Long-term hypertension control prevents heart attacks and other cardiovascular diseases, yet implementation is insufficient worldwide. The redesign of hypertension management by information and communication technology (ICT) improved hypertension control, e.g., by transmission of blood pressure (BP) measurements to a central webspace. However, an easy-to-use secure patient app connected with a practice management centre is lacking. This study evaluates the effectiveness of the newly developed PIA (PC-supported case management of hypertensive patients to implement guideline-based hypertension therapy using a physician-defined and -supervised, patient-specific therapeutic algorithm) intervention with PIA-ICT and eLearning for general practices. The effectiveness of the PIA intervention was evaluated in a cluster-randomised study. Practices were randomly allocated (1:1) to the intervention or the control group (usual care). Group allocation was unmasked for participants and researchers. The primary outcome was the BP control rate (BP<140/90mmHg) after 6-12months. Secondary outcomes included BP changes and satisfaction with PIA-ICT. The trial is registered in the German Clinical Trials Register (DRKS00012680). Starting from December 1, 2019, 64 general practices were recruited over 1 year during the COVID-19 pandemic. Overall, 848 patients were enrolled between April 15, 2020 and March 31, 2021. The study was completed Sept 30, 2021. At baseline, 636 patients (intervention: 331; control: 305) of 50 general practices met the inclusion criteria. The final dataset for analyses comprised 47 practices and 525 patients (intervention 265; control 260). In the adjusted hierarchical model, the PIA intervention increased the BP control rate significantly by 23.1% points (95% CI: 5.4-40.8%): intervention 59.8% (95% CI: 47.4-71.0%) compared to 36.7% (95% CI: 24.9-50.3%) in the control group. Systolic BP decreased by 21.1mmHg in the intervention and 15.5mmHg in the control group. The PIA redesign of care processes improved BP in an outcome-relevant way. Prospectively, it may constitute an important model for hypertension care in Germany. This study is funded by the German Innovation Fund (Grant number: 01NVF17002).

Remote Patient Monitoring for Hypertension: Feasibility and Outcomes of a Clinic-Based Pilot in a Minority Population.

In the US 48% of adults have hypertension, with direct costs in excess of $130 billion per year. Remote patient monitoring (RPM) has been discussed as a useful tool in the treatment of hypertension, but few studies evaluate its cost effectiveness or efficacy in minority, lower socio-economic (SES) populations. Our study aims to evaluate the clinical and financial outcomes of RPM in hypertension management in a primarily minority, low-SES population. In this prospective cohort pilot study, patients with uncontrolled primary hypertension (defined via Joint National Committee 8 guidelines) were randomly selected from a single academically affiliated primary care clinic. Patients were enrolled on a rolling basis for 90 days. Patients were given blood pressure cuffs and transmission hubs and asked to transmit daily blood pressure readings. Patients were called weekly by research assistants and concerns were escalated to the primary care physician. The control group was the remaining 299 uncontrolled hypertensive patients from the same clinic population analyzed via retrospective chart records at the conclusion of the interventional study period. The primary outcome was blood pressure control. Secondary outcomes were relative improvement in systolic pressure and direct costs. A total of 13 patients were enrolled into the RPM intervention; these patients were 54% female, 100% African American, and 77% Medicaid. When assessed via intention-to-treat analysis, patients in the intervention group had non-inferior blood pressure control at 90 days (46% experimental vs 31% control, P = .33) and average change in systolic blood pressure at 90 days (13.5 vs 3.7 mmHg, P = .174) while experiencing a significant reduction in office-based visits at 90 days (1.5 vs 5.9, P < .001) as compared to control. Results on per-protocol analysis also showed non-inferior BP control (63% vs 31%, P = .135). Financially, the program generated margins of $29 per patient at 90 days. Patients in our minority- and Medicaid-predominant cohort achieved noninferior blood pressure control as compared to retrospective control at 90 days and a significant reduction in all-cause clinic visits at 90 days. The program generated little revenue per patient, with main barriers to implementation including patient compliance and payor denial.

Cerebrospinal Fluid Hydrodynamics in Chiari I Malformation and Syringomyelia: Modeling Pathophysiology.

Anatomic MRI, MRI flow studies, and intraoperative ultrasonography demonstrate that the Chiari I malformation obstructs CSF pathways at the foramen magnum and prevents normal CSF movement through the foramen magnum. Impaired CSF displacement across the foramen magnum during the cardiac cycle increases pulsatile hindbrain motion, pressure transmission to the spinal subarachnoid space, and the amplitude of CSF subarachnoid pressure waves driving CSF into the spinal cord. Central canal septations in adults prevent syrinx formation by CSF directly transmitting its pressure wave from the fourth ventricle to the central canal.

Analysis on Prediction Methods for Formation Pore Pressure under Multiple Pressure Formation Mechanisms

There is abnormal fluid pressure widely distributed in Yinggehai-Qiongdongnan Basin, with abnormal zones extending from different depths, and the formation causes of abnormal pressure here are complicated. It is one of the three HTHP offshore regions in the world at present. Hence, drilling in this region is very difficult. It is discovered in drilling practices in recent years that, due to the multiple formation mechanisms of abnormal formation pressure in this region, the conventional pressure prediction model based on under-compaction theory is insufficient to explain the abnormal high pressure suddenly occurring in the middle shallow layer in diapiric structure of Yinggehai-Qiongdongnan Basin, which causes very large deviation of pore pressure prediction before drilling. Based on the basic principle of improved Fillippone method and with the three-dimensional high precision seismic velocity field of geologic modeling inversion, the authors build a three dimensional pore pressure model of target block, extract the pressure slice of horizon and across the target well, analyze the other source pressure transmission possibly caused by formation connectivity, and import them into the mathematical model of pore pressure prediction, so as to attain the purpose of improving the precision of pore pressure prediction. This method has been well applied in pre-drilling pressure prediction for the HTHP block in the South China Sea, reaching a prediction precisi on above 95%.

The Transmission Effect and Influencing Factors of Land Pressure in the Yangtze River Delta Region from 1995–2020

Human societal growth has greatly pressured available land resources. The key to reducing land pressure and fostering regional synergistic development is revealing the transmission effect of land pressure. We used a modified gravity model to construct a spatial correlation network (SCN) of the land pressure in the Yangtze River Delta region (YRDR) for the years 1995, 2000, 2005, 2010, 2015 and 2020. To examine how the land pressure is transmitted throughout the cities in the YRDR, we used a social network analysis to examine the overall network structure, individual network characteristics and spatial clustering characteristics. Finally, the center of gravity-GTWR model that coupled the inter-city interactions and the temporal non-smoothness further revealed the spatiotemporal evolution and the different patterns of the influencing factors. The results revealed that (1) the spatial correlation structure of the land pressure in the YRDR was relatively stable. Nanjing, Shanghai, Suzhou, Hangzhou and Changzhou played a significant role as linkages. (2) The YRDR was beyond the geographical limit for the land pressure transmission effect and each block had a considerable and mostly steady transmission impact. (3) The center of gravity-GTWR model that coupled the inter-city interactions and the temporal non-stationarity was a viable method for analyzing the factors that influence the land pressure. (4) There were significant regional and temporal variations in the factors influencing land pressure. The influencing factors differed in intensity and direction from city to city. Our results can provide a new perspective on relieving land pressure from the perspective of urban agglomerations and help accomplish the sustainable development of regional land resources.

On force generation in electro-fluidic linear actuators with ferrofluid

In ferrofluid actuation systems, forces are generated by actively controlling pressure and flow within the fluid using an applied magnetic field. There are multiple contributing factors in force generation involving complex non-linear couplings between electromagnetic and fluid pressure fields. This brings significant challenges in theory-based design and optimization. In this paper, a theoretical model of pressure transmission between a ferrofluid and solid is derived starting from Maxwell’s stress tensor and accounting for magnetic saturation within the fluid. This model shows that linear actuator designs based on orthogonal mode operation, where the field direction through the fluid is perpendicular to the motion direction, can provide the highest force capacity for a given field strength from the actuator coil. This is verified by theoretical analysis of some basic linear actuator topologies. The results are applied in the design and analysis of a novel piston-type linear actuator with sealed chamber and two internal electrical coils for bidirectional operation. Experimental measurements of both static and dynamic behaviour are shown to validate the described principles. The actuator produces smooth and precise flow-regulated motion, has zero intrinsic stiffness, and exhibits very low friction due to the suspension effect from ferrofluid layers within the actuator.

Multi structural parameter analysis based on the labyrinth valve design with high pressure drop and low noise

Labyrinth channel design is a key for achieving high pressure loss for the labyrinth valve in a thermal power plant. However, the labyrinth channel structures are relatively complex, with many influencing parameters. An unreasonable design generates high noise, adversely affecting personnel and equipment. In this paper, pressure drop is used as a typical parameter for evaluating pressure loss performance, while cavitation, flow velocity, and transmission loss are used as characteristic parameters for assessing noise performance. A comprehensive evaluation criteria of noise performance is constructed. The numerical models with various stage numbers, entrance widths, channel depths, transition part parameters, and expansion coefficients are established, the effects of different structural parameters on the labyrinth channel pressure loss and noise performance are systematically studied to achieve a labyrinth valve design with high pressure loss and low noise. The results show that the influence of different structural parameters on the labyrinth channel pressure loss and noise performance is not the same. The parameter selection of multi-stage, small entrance width, medium channel depth, large transition part parameters, and high expansion coefficient is important way for realizing the design of high pressure loss and low noise labyrinth valve.

Measurement of Excess Pore-Water Pressure in Frozen Soil at Subfreezing Temperatures Close to 0°C

Response of pore-water pressure has crucial effect on the engineering geological performance of permafrost ground. However, there is a dearth of literature on the measurement of pore-water pressure in frozen soils due to challenges with regard to technical and operational method. To validate the generation of pore-water pressure and to reveal its variation property in frozen soils at subfreezing temperatures close to 0°C, a miniature pressure transducer was utilized to conduct a number of confined compression tests. Double-wall structure avoided damage to the transducer during frozen soil sampling. The transducer at sample bottom perceived a pressure fluctuation as varying air pressure imposed on sample surface, proving the connectivity among the pores in frozen soils with a hysteretic effect on pressure transmission. Pore-water pressure experienced a progressive increase followed by a slow dissipation under invariable load and temperature conditions when water drainage was permitted, while a monotonic increase in pressure was observed for an undrained sample. With decreasing temperature, a smaller peak and a more dilatory dissipation were displayed. When the sample was exposed to a stepwise warming process, a similar performance for the pressure was obtained with abrupt rise at the turning point of temperature.

Three-layer model with absorption for conservative estimation of the maximum acoustic transmission coefficient through the human skull for transcranial ultrasound stimulation

Transcranial ultrasound stimulation (TUS) has been shown to be a safe and effective technique for non-invasive superficial and deep brain stimulation. Safe and efficient translation to humans requires estimating the acoustic attenuation of the human skull. Nevertheless, there are no international guidelines for estimating the impact of the skull bone. A tissue independent, arbitrary derating was developed by the U.S. Food and Drug Administration to take into account tissue absorption (0.3 dB/cm-MHz) for diagnostic ultrasound. However, for the case of transcranial ultrasound imaging, the FDA model does not take into account the insertion loss induced by the skull bone, nor the absorption by brain tissue. Therefore, the estimated absorption is overly conservative which could potentially limit TUS applications if the same guidelines were to be adopted. Here we propose a three-layer model including bone absorption to calculate the maximum pressure transmission through the human skull for frequencies ranging between 100 kHz and 1.5 MHz. The calculated pressure transmission decreases with the frequency and the thickness of the bone, with peaks for each thickness corresponding to a multiple of half the wavelength. The 95th percentile maximum transmission was calculated over the accessible surface of 20 human skulls for 12 typical diameters of the ultrasound beam on the skull surface, and varies between 40% and 78%. To facilitate the safe adjustment of the acoustic pressure for short ultrasound pulses, such as transcranial imaging or transcranial ultrasound stimulation, a table summarizes the maximum pressure transmission for each ultrasound beam diameter and each frequency.

Bottom-Gated ZnO TFT Pressure Sensor with 1D Nanorods.

In this study, a bottom-gated ZnO thin film transistor (TFT) pressure sensor with nanorods (NRs) is suggested. The NRs are formed on a planar channel of the TFT by hydrothermal synthesis for the mediators of pressure amplification. The fabricated devices show enhanced sensitivity by 16~20 times better than that of the thin film structure because NRs have a small pressure transmission area and causes more strain in the underlayered piezoelectric channel material. When making a sensor with a three-terminal structure, the leakage current in stand-by mode and optimal conductance state for pressure sensor is expected to be controlled by the gate voltage. A scanning electron microscope (SEM) was used to identify the nanorods grown by hydrothermal synthesis. X-ray diffraction (XRD) was used to compare ZnO crystallinity according to device structure and process conditions. To investigate the effect of NRs, channel mobility is also extracted experimentally and the lateral flow of current density is analyzed with simulation (COMSOL) showing that when the piezopotential due to polarization is formed vertically in the channel, the effective mobility is degraded.

Modified Laponite synthesized with special wettability as a multifunctional additive in oil-based drilling fluids

In this study, Modified Laponite with lyophobic wettability was synthesized as a multi-functional additive to solve instability of emulsions, rheological deterioration, and wellbore instability of oil-based drilling fluid. Properties and its influence on emulsion stability, rheological behavior and plugging property were investigated. The results showed that Modified Laponite was in a shape of sheet layer and had micro-meter length and nano-meter thickness which was in match with the diameter of shale pores. And it was proved to be resistant to approximately 450 °C by thermogravimetric analysis measurement. Mechanism analysis revealed that Modified Laponite could stable the oil-based drilling fluid through four sections. Firstly, Modified Laponite with lyophobic wettability could promote its existence in the interface of brine/mineral oil. Secondly, Modified Laponite could decrease the interfacial tension from 32.8 to 13.5 mN/m to maintain the emulsion particles in a small size for a long time then to ensure the emulsion stability. Thirdly, Modified Laponite could enhance the shear-thinning rheological behavior which could maintain the rheological stability and enhance the sedimentation stability in ultra-deep reservoirs with high temperature and high pressure conditions. Fourthly, Modified Laponite could plug the shale pores effectively by preventing pressure transmission and enhancing shale compressive strength, and decrease the filtration volume of oil-based drilling fluid from 7.4 mL to 2.6 mL after aging at 180 °C for 16 h to stable the wellbore. Therefore, Modified Laponite was a multifunctional additive to stable the emulsion, enhance the rheological stability and strength the wellbore stability, which could ensure the application of oil-based drilling fluid in drilling process of ultra-deep reservoirs.

VC-PPQ: Privacy-Preserving Q-Learning Based Video Caching Optimization in Mobile Edge Networks

Mobile edge caching has great advantages in alleviating video traffic pressure and reducing transmission delay, which is considered as a hopeful solution to improve video resource utilization and achieve faster service response. However, due to insufficient and non-real time acquisition of the status between edge servers and mobile users, it is still difficult for existing solutions to improve the video quality of experience (VQoE) for mobile users. Besides, due to the mobility of users and malicious third-party attacks, users may suffer the risk of personal privacy (e.g. location, trajectory, preference, etc.) leakage when requesting video services that are scattered in different areas. In order to efficiently deal with these problems, this paper proposes a privacy-preserving Q-learning based video caching optimization framework in mobile edge networks (VC-PPQ), including a privacy scheme for user data and a dynamic video caching algorithm. Specifically, in the first task, the local differential privacy model is leveraged to protect the locations and preferences of users. Then, a data aggregation model is provided to make trade-off between aggregation accuracy and privacy protection. In the second task, we further obtain the video popularity in user's area by a computation service model, then formulate a caching objective function combined with transcoding technologies. Afterwards, Q-learning is adopted to obtain the goal of caching optimization, which can achieve low delay and high hit ratio. Finally, extensive simulations prove that our VC-PPQ framework delivers prominent performance advantages in terms of user privacy and caching services, which greatly improves the VQoE of users.

Monochromatic Wave of Fluid Pressure in a Porous Rock.

From the perspective of rock mechanics, transmission of fluid pressure that drives groundwater flow is not instantaneous; instead it is a slow compressional (P) wave in porous rocks saturated with a fluid. In this paper, the approach of monochromatic wave is used to analyze the slow P-wave. Permeability is derived as a function of the frequency of the wave. The permeability appears to be a complex number which asymptotes to Darcy permeability at the low frequency end but tends to vanish at the high frequency end. With Biot theory, the permeability predicts phase velocity and the quality factor of the monochromatic wave. Using Berea sandstone as an illustrative example, the complex-number permeability can yield a lower phase velocity (within frequency of 105 -108 Hz) and a larger attenuation (for frequency above 106 Hz) than Darcy permeability does. This study extends the recent research of the low-frequency waves of fluid pressure to the regime of very high frequency.

Experimental study on characteristics and mechanisms of matrix pressure transmission near the fracture surface during post-fracturing shut-in in tight oil reservoirs

Tight oil reservoirs are usually exploited using the long horizontal well and multi-stage hydraulic fracturing technique. Meanwhile, post-fracturing shut-in has become a popular procedure in improving the performance of tight reservoir wells. However, field data indicate that there are significant differences in well production due to shut-in operation in various blocks. The matrix pressure transmission near the fracture surface plays an essential role. Up to now, the characteristics and mechanisms of pressure transmission are still unclear. In this study, we conducted the pressure transmission experiment and matrix water uptake testing. Besides, X-ray diffraction (XRD), capillary suction time (CST), cast thin section observing, and mercury intrusion testing were performed. A characterization method was established to analyze the characteristics and influential factors of pressure transmission in tight oil reservoirs. The mechanism of pressure transmission and the relationship between pressure balance time and injection depth were discussed. The results show that the pressure transmission efficiency (PTE) reduces spontaneously as the initial water saturation in pores decreases. The clay expands after absorbing water and then the particles are dispersed, which damages the pore structure and reduces the PTE. The PTE decreases with the high content of clay minerals, especially the great proportion of expansive clay minerals. The PTE increases with the growing of the permeability and the capillary radius in some situations. The junction of conglomerate complex and gravel easily break up to form micro-fractures, which improves the PTE significantly. The mechanisms of pressure transmission include injection pressure, capillary force, and chemical osmotic pressure. These mechanisms of pressure transmission will be different at each stage and various situation. The time of pressure transmission increases with the large injection depth. This study helps to reveal the characteristics and mechanisms of matrix pressure transmission near the fracture surface during the post-fracturing shut-in and provides guidance for the optimization of the shut-in schedule.

Permeability recovery by self-healing of class F fly ash-based geopolymers

Alkali activated materials (AAMs), also known as geopolymers, have been proposed as lower carbon footprint alternative cementitious materials to ordinary portland cement (OPC). Geopolymers are formed from an aluminosilicate precursor, such as fly ash, mixed with an alkaline activating solution. These materials may have self-healing behavior, which makes them promising materials for applications where controlling crack widths is critical, such as in well bores or steel-reinforced concrete structures. In this study, the self-healing ability of a Class F fly ash-based geopolymer was investigated using a pressure transmission test (PTT) to measure the initial permeability of the material, the permeability after damage using freeze-thaw cycling to initiate cracks, and the permeability following post-damage curing to encourage self-healing. The geopolymer was found to have low permeability, 0.26 ± 0.09 µD at 28 days, which is comparable to reported values for OPC. The permeability increased after damage, but then decreased again after the self-healing curing period. The results show an inverse correlation between the level of initial damage and the level of permeability restoration upon self-healing. This work indicates that geopolymers can indeed self-heal cracks to reduce damage, suggesting that they are promising barrier materials for well construction and other applications.

Numerical and experimental investigation of the sound transmission delay from a skin vibration to the occluded ear canal

High-level impulse noise can permanently damage the ear and protection is therefore essential. Using hearing protectors to occlude the external ear canal, reduces air conduction but provides only partial attenuation. This is because the pinna converts airborne sound into mechanical vibrations, which propagate through body tissues to the occluded ear canal. To better understand the propagation pathways and mechanisms, which remain unclear, we simulated a preliminary two-dimensional transient model of the external ear in COMSOL Multiphysics. It shed light on how the waves travel through the tissues to reach the occluded ear canal, illustrating phenomena that are usually not visible experimentally. We also conducted an experimental evaluation of the time delay of wave propagation between the external ear tissues and the auditory canal air to confirm the numerical observations. Thus, we measured delays to reach the ear canal during stimulation with a transducer at the back of the concha and at the tragus of 0.37 ms and 0.32 ms respectively. This matched the numerical simulations and corroborated transmission through the skin. The model also highlighted coupling between the skin and the plug leading to pressure transmission in the ear canal. These preliminary results pave the way for the improvement of hearing protection devices by demonstrating the impact of the protection device’s material and coating on the radiative phenomena resulting from the tissue conduction.

ANALYSIS OF BRAKE SYSTEMS IN MOTOR VEHICLES USING PRACTICAL EXAMPLES FROM THE ASPECT OF THEIR DIAGNOSTICS

The part of the braking system that has the task of transmitting the command activated by the driver to thebrakes is called the transmission mechanism. The transmission mechanism itself can be different depending on howit is constructed and conceptually executed. As for the conceptual solution, the question arises as to whether thetransmission method itself must be such that the driver's command is only transmitted to the brakes or the driver'scommand itself is handed over to a separate energy system. The energy system itself can be such that it additionallyhelps the activation of the brakes (servo brake force boosters) or completely takes over the activation of the brakes,with the creation of a certain braking force on the wheels, and these are the so-called mechanisms with full servoaction. Today we have the following transmission mechanisms in use: Mechanical transmission, hydraulic with orwithout servo amplification, hydraulic with full servo action, pneumatic with full servo action, hydro-pneumaticwith servo amplification or with full servo action. The very choice of these systems depends on a large number offactors, but the main one is - how much energy must be delivered to the brakes. Each of these systems is explainedseparately in the paper. A mechanical transmission mechanism is a system that does not have any additional servoamplification, but the command of the driver or the person operating the machine is directly transmitted to thebrakes. Based on this, we can conclude that the application of this transmission mechanism in brake systems is quitelimited. Today, this transmission mechanism is only used as a service brake on some slower trucks and tractors. Thehydraulic transmission mechanism is the system that is most common in brake systems of passenger, light cargo anddelivery vehicles. In the case of vehicles weighing up to 1000 kg, the driver alone is sufficient to develop thenecessary energy for braking, so it is not necessary to additionally support the braking force with servo boosters. Butthat's why smaller trucks and delivery vehicles need additional help from a servo booster to activate the brakingforce. Servo amplifiers have become an integral part of the equipment in passenger vehicles primarily due to thesafety, security and comfort of passengers. In contrast to the mechanical transmission, this system is morecomplicated in terms of performance and its operation is based on the transmission of pressure through the brakefluid from the main brake cylinder to the brake cylinder in the brakes. The pressure created by the brake fluid actson the pistons in the cylinder itself and in this way force is created and the brakes are activated. The main advantageof this system is the very safety and safer braking, because with the hydraulic system it is possible to make adistribution in several independent branches to the cylinders on the brakes, and this is one of the basic satisfactoryrequirements in the ECE regulation that the brakes must also have an auxiliary braking system in case dismissal ofthe principal. The system itself consists of: the pedal, which is activated by pressing the foot on the pedal itself, themain brake cylinder, the distribution system, the working brake cylinders in the brakes and the brake itself.

Nasal Cannula with Long and Narrow Tubing for Non-Invasive Respiratory Support in Preterm Neonates: A Systematic Review and Meta-Analysis.

Background: Cannulas with long and narrow tubing (CLNT) are increasingly being used as an interface for noninvasive respiratory support (NRS) in preterm neonates; however, their efficacy compared to commonly used nasal interfaces such as short binasal prongs (SBP) and nasal masks (NM) has not been widely studied. Material and Methods: Medline, Embase, CENTRAL, Health Technology Assessment Database, and Web of Science were searched for randomized clinical trials (RCTs) and observational studies investigating the efficacy of CLNT compared to SBP or NM in preterm neonates requiring NRS for primary respiratory and post-extubation support. A random-effects meta-analysis was used for data synthesis. Results: Three RCTs and three observational studies were included. Clinical benefit or harm could not be ruled out for the outcome of need for invasive mechanical ventilation (IMV) for CLNT versus SBP or NM [relative risk (RR) 1.37, 95% confidence interval (CI) 0.61–3.04, certainty of evidence (CoE) low]. The results were also inconclusive for the outcome of treatment failure [RR 1.20, 95% CI 0.48–3.01, CoE very low]. Oropharyngeal pressure transmission was possibly lower with CLNT compared to other interfaces [MD −1.84 cm H20, 95% CI −3.12 to −0.56, CoE very low]. Clinical benefit or harm could not be excluded with CLNT compared to SBP or NM for the outcomes of duration of IMV, nasal trauma, receipt of surfactant, air leak, and NRS duration. Conclusion: Very low to low CoE and statistically nonsignificant results for the clinical outcomes precluded us from making any reasonable conclusions; however, the use of CLNT as an NRS interface, compared to SBP or NM, possibly transmits lower oropharyngeal pressures. We suggest adequately powered multicentric RCTs to evaluate the efficacy of CLNT when compared to other interfaces.