System Parameters Research Articles

Predicting a Wide Range of Fractal Dimensions of Salt-Induced Aggregates in Water Using a Random Forest Model.

Salt-induced colloidal aggregates can significantly influence contaminant fate and transport in natural and engineered systems. These aggregates' fractal dimensions (df), ranging from 1.4 to 2.2, depend on various system variables. However, the quantitative relationship between these variables and df of aggregates has not been fully explored, especially in predicting a wide range of df. Here, we developed a random forest model capable of predicting the complete range of aggregate df using just four simple physical and chemical parameters of the aggregating system as inputs. The model accurately predicts the df of aggregates formed by colloids of different sizes, ranging from nano to micro sizes, after being trained and tested on appropriate data sets. Ionic strength (IS) has the most significant influence on the df of aggregates formed by microsized particles followed by the relative hydrodynamic radius of aggregates (Rh/Rp), particle concentration (Cp), and primary particle radius (Rp). For aggregates formed by both nano- and microsized particles, IS still has a strong influence on the df, with the significance of Rp increasing. All four inputs are negatively correlated with predicting the df of aggregates. The predictions align well with the physical interpretations.

Statistical inference with a manifold-constrained RNA velocity model uncovers cell cycle speed modulations.

Across biological systems, cells undergo coordinated changes in gene expression, resulting in transcriptome dynamics that unfold within a low-dimensional manifold. While low-dimensional dynamics can be extracted using RNA velocity, these algorithms can be fragile and rely on heuristics lacking statistical control. Moreover, the estimated vector field is not dynamically consistent with the traversed gene expression manifold. To address these challenges, we introduce a Bayesian model of RNA velocity that couples velocity field and manifold estimation in a reformulated, unified framework, identifying the parameters of an explicit dynamical system. Focusing on the cell cycle, we implement VeloCycle to study gene regulation dynamics on one-dimensional periodic manifolds and validate its ability to infer cell cycle periods using live imaging. We also apply VeloCycle to reveal speed differences in regionally defined progenitors and Perturb-seq gene knockdowns. Overall, VeloCycle expands the single-cell RNA sequencing analysis toolkit with a modular and statistically consistent RNA velocity inference framework.

Kinematical signatures: Distinguishing between warps and radial flows

Increasing evidence shows that warped disks are common, challenging the methods used to model their velocity fields. Molecular line emission of these disks is characterized by a twisted pattern, similar to the signal from radial flows, complicating the study of warped disk kinematics. Previous attempts to model these features have encountered difficulties in distinguishing between the underlying kinematics of different disks. This study aims to advance gas kinematics modeling capabilities by extending the Extracting Disk Dynamics ( eddy ) package to include warped geometries and radial flows. We assess the performance of eddy in recovering input parameters for scenarios involving warps, radial flows, and combinations of the two. Additionally, we provide a basis to break the visual degeneracy between warped disks and radial flow, establishing a criterion to distinguish them. We extended the eddy package to handle warped geometries by including a parametric prescription of a warped disk and a ray-casting algorithm to account for the surface self-obscuration arising from the 3D to 2D projection. The effectiveness of the tool was tested using the radiative transfer code RADMC3D generating synthetic models for disks with radial flows, warped disks, and warped disks with radial flows. We demonstrate the efficacy of our tool in accurately recovering the geometrical parameters of systems, particularly in data with sufficient angular resolution. Importantly, we observe minimal impact from thermal noise levels typical in Atacama Large Millimeter/submillimeter Array (ALMA) observations. Furthermore, our findings reveal that fitting an incorrect model type produces characteristic residual signatures, which serve as kinematic criteria for disk classification. Characterizing gas kinematics requires careful consideration of twisted motions. While our model provides insights into disk geometries, caution is needed when interpreting parameters in regions with complex kinematics or low-resolution data. Future ALMA baseline observations should help clarify warped disk kinematics.

Influenza and non-influenza ARVI in children. A relationship between cytokine profile, parameters of the “lipid peroxidation – antioxidant defense system” as well as clinical and laboratory indicators

Influenza and acute respiratory viral infections (ARVI) impose a substantial damage to the population health in the Russian Federation due to their seasonal circulation and predominantly affect young children. A very few data on the cytokine profile, the nonspecific LPO — AOD system and their relationships with clinical characteristics in such diseases in preschool children are available. The aim of this study was to assess the cytokine profile, LPO — AOD system parameters and their relationship with the clinical and laboratory characteristics of diseases in preschool children with influenza and other ARVI. 86 preschool children (3–6 years old) were examined: with an established diagnosis of influenza (n = 31), non-influenza ARVI (n = 28), apparently healthy children (control group (n = 27). All pediatric samples were analyzed by enzyme-linked immunosorbent assay assessing blood serum concentrations of C-reactive protein and cytokines IL-1β, IL-4, IL-6, IL-8, TNFα, IFNα, IFNγ. Spectrophotometric, fluorometric and enzyme immunoassay methods to assess the state of the “LPO — AOD” system were used. In the group of children with influenza vs other ARVI, a higher incidence of intoxication syndrome was revealed. Cytokine profile in children from both clinical groups compared with control cohort was featured with higher indicators of both pro-inflammatory and anti-inflammatory origin. Children with non-influenza ARVI, had increased magnitude of LPO final products in the nonspecific LPO — AOD system along with lowered concentration of fat-soluble vitamins, general antioxidant activity, GSH level, and SOD activity. In the group with influenza, the level of primary and final lipid peroxidation products was increased, whereas that of for retinol,α-tocopherol, and total antioxidant activity was decreased paralleled with higher GSSG and SOD levels. Numerous correlations were noted in the group of children with ARVI: IL-1β/ketones, IL-6/ketones, IL-8/ketones, TNFα/ketones, IL-4/ketones, IFNg/shortness of breath, IFNα/cough, double bonds/fever, double bonds/AST, SO/intoxication, retinol/fever, GSSG/cough. The influenza group differed in the following relationships: IL-4/ketones, IL-4/fever, IFNα/ketones, CDs/AST. It can be concluded that in preschool children with ARVI and influenza, changes in the cytokine profile are accompanied by increased pro- and anti-inflammatory cytokine levels, increased intensity of lipid peroxidation reactions along with reduced magnitude of antioxidant factors. In the group with ARVI, there was a relationship between the final toxic products of lipid peroxidation — Schiff bases — and the intoxication index, as well as the presence of protective mechanisms in the form of connections between interferons and disease clinical manifestations. The group with influenza was distinguished by the presence of protective relations, which may have a beneficial effect in the context of developing pathological process. The data obtained will help expand the understanding of the pathogenetic mechanisms related to immune reactivity and nonspecific lipid peroxidation reactions in preschool patients and formulate appropriate measures for correction.

Kaf İçi ve Dışına Lidokain Uygulamasının Ekstübasyon Sonrası Görülen Kardiyovasküler ve Solunum Sistemi Yanıtlarına Etkileri

Objective: In our investigation, we aimed to assess the efficacy of employing lidocaine spray application around endotracheal tube cuff (ETTC) prior to intubation, alongside and the use of intracuff lidocaine application following intubation. Our primary objective encompassed an examination of the resultant effects on the cardiovascular and respiratory systems leading up to the extubation phase. Methods: Two hundred patients scheduled for gynecologic operations, with an ASA physical status of I or II and aged between 18 and 65 years, undergoing general anesthesia lasting over one hour, were recruited for the study. Patients were allocated into four groups. Group I involved the inflation of the endotracheal tube cuff with air following intubation. In Group II, 10% lidocaine was sprayed around the ETTC prior to intubation. Group III entailed the inflation of the ETTC with 2% lidocaine after intubation. Lastly, Group IV received both the pre-intubation application of 10% lidocaine spray around the ETTC and the inflation of the cuff with 2% lidocaine following intubation. Cardiovascular parameters in the early post-extubation period and occurrences of postoperative sore throat, cough, and hoarseness up to 48 hours post-operation were documented for analysis. Results: Increases were observed at cardiovasvular system parameters after extubation in all groups continued for 5 or 15 minutes. Postoperative data for sore throat, cough and hoarseness were smilar in all groups. Conclusion: The study revealed that the administration of 10% lidocaine spray around the ETTC, as well as the use of 2% lidocaine within the cuff alone or in combination, did not result in a reduction of cardiovascular system responses during the early post-extubation period. However, these interventions did lead to a decrease in postoperative respiratory system side effects, albeit not providing complete prevention of such occurrences. Keywords: Lidocaine, endotracheal tube cuff, extubation, hemodynamic, pulmonary

Determination of converter parameters for high-voltage electromechanical systems of stationary installations of industrial fans

Purpose. To study the electromagnetic processes in the circuit of the phase rotor of a high-voltage induction motor connected to the network through a step-up converter, to determine the parameters of the converter and their relationship with the voltage gain to ensure the optimal level of energy efficiency of the electromechanical system. Methodology. Methods of theoretical electrical engineering for the construction of a rotor circuit replacement scheme for an induction motor with a step-up converter, methods for solving a system of first-order differential equations, analytical methods. Findings. The expediency of using a converter that combines the rotor circuit of a high-voltage induction motor with the power supply network and provides regulation of the rotor EMF with the recovery of the slip energy of the induction motor rotor to the power supply network has been proved. This will ensure speed control of powerful high-voltage induction motors on the rotor side with an EMF of up to 600 V and significantly reduce the cost of a high-voltage electromechanical system. A methodology for determining the converter gain and the parameters of the rotor circuit of the electromechanical system is proposed, which allows determining the transformation ratio of the matching transformer at the optimal value of the voltage gain. The conditions of trouble-free operation of the inverter at the moment of start-up of the electromechanical system are determined. Achieving these conditions is ensured by determining the delay of the control signal to the power keys of the inverter of a step-up converter. The correlation between the voltage gain and the equivalent resistance of the rotor circuit of the electromechanical system is established. Originality. The ratio of the voltage gain to the equivalent resistance of the rotor circuit of the electromechanical system is established, which will ensure the matching of the rotor EMF with the voltage of the power supply network while maintaining a high level of energy efficiency. Practical value. A methodology for determining the gain and parameters of a step-up converter is proposed, which allows determining the transformation ratio of a matching transformer at the optimal value of the voltage gain. The proposed methodology can be applied to the modelling of complex powerful high-voltage electromechanical systems, especially for stationary installations of industrial fans.

Increasing the efficiency of operation and management of railroad transport infrastructure based on maximum levels of fault tolerance

This paper considers the optimization of parameters for a railroad transport system. The maximum level of technological reliability and the average time spent by trains on the route are used as optimization criteria. The purpose of the study is to establish the optimal parameters for the operational process of railroad transport systems according to the criterion of the maximum level of technological reliability and the minimum time of trains on the route. Methods of technological reliability research have been proposed. Taking into account that the entire technological process is a sequential set of technological elements, a simulation model of the technological process of the transit transport-technological line along a route direction has been built. A population of agents that simulates the operation of railroad sections of the rotation of train locomotives and is a key subsystem of the simulation model has been developed and configured. The simulation model makes it possible to optimize the parameters of multi-section railroad lines. This approach is provided owing to the agent approach. As a result of the experiments, the optimal parameters of the functioning of railroad lines were established when organizing the passage of transit trains. The coefficient of utilization of the locomotive fleet fluctuates within the optimal range (0.55–0.65), which indicates the sufficiency of traction resources in the railroad system. The optimal parameters of the railroad transport system were established experimentally using the example of a train flow of 85 pairs of trains on a two-track route with five sections. The problem of "abandoned trains" has a solution but, to this end, it is necessary to increase the fleet of train locomotives by 150–200 % relative to existing standards. At the same time, even with an unlimited fleet of train locomotives, there is a fairly high probability (up to 30–50 %) of technological failures

Automatic control system for the electric drive of an overhead crane considering elastic connections

Purpose. Investigation of the peculiarities of the automatic control system of an overhead crane electric drive with regard to elastic connections.. Research methods. To achieve this goal, we used the methods of system analysis and modeling with the help of software tools. This made it possible to reflect accurately the processes occurring in the system, as well as to test various operating scenarios and their impact on the overall system efficiency. Results. The study considered the automatic control system of the electric drive and the importance of taking into account elastic connections. The proposed adaptive system uses the RBF neural network. The use of the proposed controller ensures resistance to disturbing influences and allows to level the load oscillations. The adaptability of the system is ensured by changing the parameters (load, speed of movement of mechanisms, stiffness, positioning accuracy, etc.) to meet the operating conditions of the overhead crane. Thanks to this, the system is able to operate efficiently even under variable loads and external influences. Computer modeling of the proposed control system was carried out, which confirmed its effectiveness under various operating conditions. Scientific novelty.This system provides damping of load oscillations and increases the crane positioning accuracy. This is achieved by comparing it with existing control methods according to various criteria. It is proposed to use an algorithm for adapting the parameters of the control system in real time (load, trolley speed, cable length, mechanism stiffness, etc.), which significantly improves (by 5-7% positioning accuracy, by 8-10% stability) the performance of the system. In addition, the study confirmed the ability of the system to adapt to different operating conditions (changed load, variations in travel speed, uneven external disturbances), ensuring the stability and reliability of its operation, which is especially important for ensuring continuous operation of the crane in industrial environments. Practical value. The use of this system can increase the overhead crane productivity by 5-10% compared to traditional control systems. Implementing the system in an industrial environment will significantly improve the efficiency and safety of the crane, as well as reduce maintenance and repair costs. In addition, this system can be used to modernize existing cranes, which will extend their service life and improve their reliability. This opens up new opportunities to improve the efficiency of industrial processes associated with the use of overhead cranes and provides better working conditions for operators.

Enhanced Broadband Tri-Stable Energy Harvesting System by Adapting Potential Energy – Experimental Study

Abstract This paper presents the process optimization of some key parameters, such as the size of the air gap and distance between fixed neodymium magnets to enhance the vibration-based energy harvesting effect in the tri-stable energy harvesting systems and the improved tri-stable energy harvesting system being the proposed solution under weak excitation. In order to do it, firstly the distributed parameters model of the magnetic coupling energy harvesting system, including macro fiber composites of the 8514 P2 with a homogenous material in the piezoelectric fiber layer and nonlinear magnetic force, was determined. The performed numerical analysis of the conventional and the improved tri-stable energy harvesting system indicated that introducing an additional magnet to the tri-stable system leads to the shallowing of the depth of a potential well by decreasing the air gap between magnets and consequently generating higher power output and improving the effectiveness of the proposed improved tri-stable energy harvesting system. Experiments carried out on the laboratory stand allowed us to verify the numerical results as well as determine the optimal parameters of the magnetic coupling system. Due to it, the effectiveness of the proposed system versus the conventional tri-stable energy harvesting system is most enhanced.

Blazar S 0528+134 is possibly the most powerful emitter in the Universe, including in the range of gravitational waves

A new method of determining the parameters of close binary systems of supermassive black holes (SMBHs) and the level of gravitational waves (GWs) on the Earth's surface are proposed. Data are presented from long-term monitoring of possibly the most powerful emitter in the Universe, S 0528+134, at five frequencies in the radio range from 4.8 GHz to 37 GHz, obtained by the RT-22 radio telescope of the Radio Astronomy Laboratory CrAO in Simeiz, the RT-26 radio telescope at Michigan Observatory, and the 40 m radio telescope of the Owens Valley Radio Observatory. The dynamics of powerful flares that have occurred in the object since its discovery in a sky survey in 1970 were considered. The main physical characteristics of binary SMBHs located in the central regions of the system were obtained. These data were used to find the masses of the SMBH companions, the parameters of their orbits, the energy reserve of the system, and the lifetime of the object before the SMBHs' merger. The level of GWs on the Earth's surface was determined and the possibility of their detection by International Pulsar Timing Array (IPTA) GW detectors was considered.

The Construction of Analytical Exact Soliton Waves of Kuralay Equation

Abstract The primary objective of this work is to examine the Kuralay equation, which is a complex integrable coupled system, in order to investigate the integrable motion of induced curves. The soliton solutions derived from the Kuralay equation are thought to be the supremacy study of numerous significant phenomena and extensive applications across a wide range of domains, including optical fibres, nonlinear optics and ferromagnetic materials. The inverse scattering transform is unable to resolve the Cauchy problem for this equation, so the analytical method is used to produce exact travelling wave solutions. The modified auxiliary equation and Sardar sub-equation approaches are used to find solitary wave solutions. As a result, singular, mixed singular, periodic, mixed trigonometric, complex combo, trigonometric, mixed hyperbolic, plane and combined bright–dark soliton solution can be obtained. The derived solutions are graphically displayed in 2-D and 3-D glances to demonstrate how the fitting values of the system parameters can be used to predict the behavioural responses to pulse propagation. This study also provides a rich platform for further investigation.

Orthogonal dispersion modeling of double-stage VIPA spectrometer in SBS system

Brillouin microscopy enables the assessment of the mechanical properties of biological tissues by mapping the Brillouin shift in three-dimensional (3D), all-optical, label-free, non-contact, and subcellular resolution. The virtually imaged phased array (VIPA) etalon is widely utilized for measuring Brillouin spectra owing to its superior light throughput, large angular dispersion, and rapid signal acquisition capabilities. The VIPA-based spectrometer plays a significant role in Brillouin microscopy, but it is highly sensitive to factors such as the tilt angle, beam radius, lens focal length, and so on. Here, we propose an orthogonal dispersion model based on paraxial wave theory. This model is employed to explore the output intensity distribution and dispersion characteristics of a double-stage VIPA spectrometer. To validate the proposed model, we develop a stimulated Brillouin scattering (SBS) system by leveraging the optimal spectrometer parameters to measure the Brillouin frequency shift in pure water. We demonstrate the capabilities of this model in mitigating spectral dispersion and enhancing spectral measurement accuracy by optimizing the spectrometer's system parameters. This work is pivotal for the future deployment of the double-stage VIPA spectrometer in SBS-based microscopy applications.

Nonlinear vibration analysis of multi-support oil-tank system in aero-engine based on asymptotic methods

This article is primarily focused on the complicated nonlinear vibration behavior of an aero-engine lubricating oil-tank system with multiple nonlinear pedestals. First, the rubber damping ring’s nonlinear factors are introduced into a cubic nonlinear dynamic model of lubricating oil-tank system. The nonlinear system parameters are identified by testing a simplified aero-engine lubricating oil-tank structure. Then, the nonlinear dynamic model is solved via asymptotic approach, and results are confirmed using Runge-Kutta numerical analysis approach. The system’s vibration responses and amplitude-frequency curves are also acquired, and influence of system parameters on nonlinearity is analyzed. Finally, an experimental investigation on the simplified oil-tank is performed. The nonlinear vibration characteristics of the rubber damping ring and its vibration reduction mechanism are verified using vibration transmissibility. The experimental results are consistent with numerical results. This paper’s recommended analysis approach has engineering significance for vibration and noise reduction design of aero-engine components.

Assessment of Conical Solar Stills Empowered by N-Replicated Partially Shaded PVT-CPC Collectors: Unveiling Exergo-Enviro-Economic Dynamics, Productivity and Cogeneration Efficiency

Abstract The economic and environmental dimensions play a pivotal role in evaluating solar still systems. The aim of this study is to evaluate the performance, efficiency, and viability of conical solar still integrated with multiple identical photovoltaic-thermal compound parabolic collectors (PVT-CPC) through comprehensive analyses of cogeneration efficiency, exergoeconomic and enviroeconomic factors, and productivity metrics. The results of this study were obtained through MATLAB programming, enabling accurate and detailed computations. The model has been validated at N=0 and N=1, showing strong correlation results: 0.96 and 0.97 for water temperature, 0.99 for yield in both cases, and 0.99 and 0.98 for glass temperature respectively. The system has achieved a total carbon emissions mitigation of 108.29 tCO2 based on energy and 12.44 tCO2 based on exergy while recording an annual yield of 2199.61 kg. The annual cogeneration efficiency, exergo-economic parameter, enviro-economic parameter, and annual productivity are 38.96%, 31.98 kWh/,1570.20 and 244.68% respectively. Furthermore, the obtained results have been compared with prior research and concluded that the exergoeconomic and enviroeconomic parameters for the proposed system are increased by 93.54% than the solar still with water cooled condensing surface and 94.71% than solar still containing partially coated condensing cover with thermoelectric cooling.

Artificial intelligence in medicine: neural networks for analyzing systemic hemodynamics

Artificial neural networks are capable of efficiently processing large data sets, as well as solving the tasks of prediction, classification and data recovery. The article considers each of the above tasks in detail and studies literature sources devoted to the topic under study. Artificial neural networks cope with the tasks with a high degree of accuracy. The methods of application of neural networks for the analysis of systemic haemodynamics are described. Modern neural networks can analyse medical data and are able to work with incomplete data, find hidden patterns in them, and can be adapted to solve a wide range of problems. Our laboratory is developing an artificial neural network capable of classifying indicators describing the state of haemodynamics of subjects and recovering missing or incomplete data. Thus, artificial neural networks can act as an efficient method of analysing systemic hemodynamic parameters.

Static and dynamic power splitting protocol enabled in DF energy harvesting Half-Duplex relaying network: Ergodic capacity analysis

In this research, we propose and examine the DF Energy Harvesting Half-Duplex Relaying Network. For this system model, the DF Energy Harvesting Half-Duplex Relaying Network is analyzed in two cases: Static and Dynamic Power Splitting Protocol. The Ergodic Capacity (EC) is introduced and derived in relation to all the primary system parameters in order to evaluate system performance. The Monte Carlo simulation results demonstrate that the mathematical and simulation are in agreement, thereby confirming the accuracy of the analytical description.

X-ray and optical observations of the millisecond pulsar binary PSR J1431–4715

We present the first X-ray observation of the energetic millisecond pulsar binary PSR J1431−4715, performed with XMM-Newton and complemented with fast optical multi-band photometry acquired with the ULTRACAM instrument at ESO-NTT. It is found as a faint X-ray source without a significant orbital modulation. This contrasts with the majority of systems that instead display substantial X-ray orbital variability. The X-ray spectrum is dominated by non-thermal emission and, due to the lack of orbital modulation, does not favour an origin in an intrabinary shock between the pulsar and companion star wind. While thermal emission from the neutron star polar cap cannot be excluded in the soft X-rays, the dominance of synchrotron emission favours an origin in the pulsar magnetosphere that we describe at both X-ray and gamma-ray energies with a synchro-curvature model. The optical multi-colour light curve folded at the 10.8 h orbital period is double-humped and dominated by ellipsoidal effects, but also affected by irradiation. The ULTRACAM light curves are fit with several models encompassing direct heating and a cold spot, or heat redistribution after irradiation either through convection or convection plus diffusion. Despite the inability to constrain the best irradiation models, the fits provide consistent system parameters, giving an orbital inclination of 59 ± 6° and a distance of 3.1 ± 0.3 kpc. The companion is found to be an F-type star, underfilling its Roche lobe (fRL = 73 ± 4%) with a mass of 0.20 ± 0.04 M⊙, confirming the redback status, but hotter than the majority of redbacks. The stellar dayside and nightside temperatures of 7500 K and 7400 K, respectively, indicate a weak irradiation effect on the companion, likely due to its high intrinsic luminosity. Although the pulsar mass cannot be precisely derived, a heavy (1.8−2.2 M⊙) neutron star is favoured.

Adaptive generation of optical single-sideband signal with dually modulated EML

The optical single sideband (SSB) transmitter based on dual modulation of an electro-absorption modulation laser (D-EML) has attracted considerable attention for its capability of monolithic integration and high output power. A model-based modulation method has been developed recently for generating high-quality optical SSB signals with this D-EML scheme. However, this method requires accurate characterization of the EML’s chirps and pre-compensation for frequency responses of all-optical/electrical components, as well as the path difference between two driving signals. This imposes notable requirements on the transmitter characterization in practical applications. In this paper, we propose an adaptive method to approach the required responses of the pre-compensation filters for this optical SSB transmitter. This method avoids cumbersome device characterization and shows great resilience to the variation of system parameters. By using the proposed adaptive method, we generate a 56 Gb/s optical SSB orthogonal frequency-division multiplexed signal with the sideband suppression power ratio exceeding 21 dB. It is convenient with this method to switch the devices, i.e., directly modulated laser (DML) or electro-absorption modulator (EAM), to be pre-compensated for the optical SSB signal generation. Moreover, this method exhibits good tolerance to the path delay (±15 ps) between DML and EAM, as well as modulation depth. We also successfully transmit this signal over 80 km long standard single-mode fiber.

Spatial pilot reassignment algorithm for channel estimation stage of cell-free multi-ARS communication systems

In this paper, we investigate the user throughputs of a Cell-Free (CF) system with multiple aerial relay stations (ARSs), where each ARS is defined as an unmanned aerial vehicle (UAV)-mounted relay station. The system operates under a decode-and-forward (DF) protocol and facilitates connectivity between a terrestrial base station (TBS) and terrestrial users. ARSs are equipped with multiple antennas and simultaneously serve users that are outfitted with single antennas and distributed in a specific area. Additionally, a small-cell (SC) system based on the CF structure, where each ARS serves one user with the best channel conditions, is also considered. We analyze system communication in two stages, including user-ARS links and ARS-TBS links, and then we derive expressions for the data rate of users and ARSs. Moreover, we propose the spatial pilot reassignment (SPR) algorithm to optimize pilot assignment, enhancing channel estimation over random pilot assignment methods. The user throughput is evaluated by altering several system parameters, including the with/without data power control, the number of users, the number of ARSs, and the time interval allocated for channel estimation. The results show that the SPR algorithm improves throughput by about 10% compared to the random pilot assignment method at a 90%-likely user throughput, which is equal to a cumulative distribution function value of 0.1.

Novel parameters for micra transcatheter pacing system implantation on the right ventricular mid-septum

Abstract Background No procedural parameters for Micra transcatheter pacing system (Micra TPS) implantation on the right ventricular mid-septum have been established though it is encouraged for safety. Purpose We aimed to investigate procedural predictors for Micra TPS implantation on the ventricular mid-septum. Methods This is a single-center, retrospective and observational study. Eighty-two patients who underwent Micra TPS implantation were enrolled. The implantation sites of the ventricular septum were classified into basal, mid and apical-septum in the right anterior oblique 35° image. Predictors for mid-septal implantation were evaluated using univariable and multivariable logistic regression analysis which involved explanatory variables considered clinically important. The explanatory variables included the angle between the axis of a device cup of a delivery catheter and the tangent of the ventricular septum in the left anterior oblique 45° image (defined as angle θ). The diagnostic cut-off value of the significant predictor for mid-septal Micra implantation was assessed using receiver operating characteristic (ROC) curve analysis. Results Micra TPS was implanted on the ventricular mid-septum in 61 patients (74.4%), the apical-septum in 21 patients (25.6%), and the basal-septum in no patients. In univariable logistic regression analysis, each angle θ and α-loop shape appearance of a delivery catheter was significantly associated with mid-septal implantation (Odds ratio [OR], 1.1; 95% confidential interval [CI], 1.02-1.10; P=0.002, and OR, 4.6; 95% CI, 1.63-13.6; P=0.005, respectively). After multivariable adjustment, both angle θ and α-loop shape appearance were independently associated with mid-septal implantation (adjusted OR, 1.1; 95% CI, 1.01-1.09; P=0.010, and adjusted OR, 3.3; 95% CI, 1.01-11.4; P=0.048, respectively). Because no Micra TPS was implanted on the basal-septum, an ROC curve for binary outcome of mid-septal and apical-septal implantation was drawn. The ROC curve showed a cut-off value of angle θ for Micra TPS implantation on the ventricular mid-septum was 22° with high sensitivity and specificity at 80.0% and 70.0% (area under the curve= 0.781). Conclusion The angle θ ≧ 22°and the α-loop shape appearance of a delivery catheter may be useful predictors for Micra TPS implantation on the ventricular mid-septum.