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In this study, a lumped parameter model which includes systemic circulation, cerebral blood vessels, systemic arteriolar resistance control, heart rate control, cerebral autoregulation mechanisms and cerebral CO2 reactivity was developed to simulate healthy and heart failure conditions. In the healthy cardiovascular system model, the results were obtained with all control mechanisms connected to the model. Whilst heart failure cases were simulated, all control mechanisms were removed from the model. Then, cerebral autoregulation and cerebral CO2 reactivity mechanisms were connected to the model. Lastly, systemic arteriolar resistance and heart rate control mechanisms were connected to the model. Also, Monte Carlo Analysis was performed to determine the range of parameters controlled for simulations of healthy and heart failure conditions. The results showed that blood flow rate in cerebral circulation can be simulated more accurately by modeling interaction among autoregulatory mechanisms rather than studying separately. [ABSTRACT FROM AUTHOR]

In this study, a computational model was proposed to assess the interaction among systemic arteriolar resistance control, heart rate control, ventricular elastance control, venous compliance control, respiratory control, cerebral autoregulation mechanisms, and cerebral CO2 reactivity for both healthy and heart failure conditions. The aim of the study is to develop a computational model to evaluate cerebral blood flow rate during exercise for both healthy and systolic heart failure conditions. The simulations were performed at rest and during exercise. Furthermore, Monte Carlo analysis was used to estimate the range of the controlled parameters for each condition. The mean arterial pressure increased progressively with respect to workload during exercise in both healthy and heart failure conditions. Total cerebral blood flow rate was found 730 mL/min at rest in the healthy cardiovascular system model. As for the simulation during exercise, the increments in cerebral blood flow rate were 11% at 25 W workload, 20% at 50 W workload, and 24% at 75 W workload. The left ventricular ejection fraction decreased from 54 to 26% in the cardiovascular model simulating heart failure. Also, total cerebral blood flow rate decreased to 604 mL/min at rest in the cardiovascular system model simulating heart failure. The increments in cerebral blood flow rate in the simulation during exercise were 14% at 25 W workload, 24% at 50 W workload, and 30% at 75 W workload in the case of heart failure. The proposed numerical model simulates cerebral blood flow rate within physiological range during exercise and heart failure. [ABSTRACT FROM AUTHOR]

With respect to the ever‐increasing performance needs in communication technologies, the need for accurate and computational efficient design optimization methods for high‐end microwave designs are also increased. Many studies had been proposed for the last decades for creating numerical modeling methods for having high accurate, stable, and computation efficient solutions suitable to be used in the design optimization process. Ensemble learning is a technique that the models are strategically created and combined to solve a specific computer intelligence challenge and primarily employed to boost the efficiency of a model or to lower the risk of a weak learner collection. Herein, XGBoosting‐based ensemble learning had been used for having surrogate models for three different microwave designs. In the first and second study cases, two microwave designs from the literature are taken into consideration for testing the performance of the proposed model with existing methods. Furthermore, a novel antenna design had been studied as a third study case with sparse training samples, to test the performance of the proposed modeling technique. As a result, the proposed method had achieved a remarkable performance for all the mentioned study cases both based on its own performance measures and its comparison with the counterpart algorithms. [ABSTRACT FROM AUTHOR]

In this work, a high-performance voltage and current output instrumentation amplifier circuit is proposed. The proposed circuit also has voltage-mode (VM) and transadmittance-mode (TAM) outputs at a time. It employs a single current backward transconductance amplifier (CBTA) and a grounded resistor. It has the advantage of having low input and high output impedances which makes it easy for cascadability. The presented circuit has electronically tunable property due to the bias current of the CBTA. The validity of the proposed circuit is demonstrated by PSPICE simulations using a 0.18 μ m CMOS process with ± 0. 9 V supply voltage. Simulation results show that the proposed circuit has a high common mode rejection ratio (CMRR), wide bandwidth, low offset and high gain properties. [ABSTRACT FROM AUTHOR]

In this paper, a new floating analog memristance simulator circuit based on dual-output operational transconductance amplifiers (DO-OTA) and passive elements is proposed. Theoretical derivations are presented which describe the circuit characteristics. DO-OTA active elements in the proposed circuit are realized with CMOS transistors, and PSPICE simulations are performed. Also workability of the circuit is tested experimentally by using commercially available integrated circuits. Theoretical derivations are validated with PSPICE simulation and experimental results. All results show that proposed simulator circuit provides frequency-dependent pinched hysteresis loop and nonvolatility feature. Exciting frequency, minimum and maximum memristance values and memristance range can be adjustable electronically with bias currents by changing the transconductances of DO-OTAs. Simulator circuit has a frequency range of 1 Hz-180 kHz. [ABSTRACT FROM AUTHOR]

Abstract A new voltage-mode (VM) proportional integral derivative (PID) controller employing only a single active component named Current Feedback Operational Amplifier (CFOA), two resistors and two grounded capacitors is proposed. The proposed PID controller employs a canonical number of only grounded capacitors without requiring any critical passive component matching conditions and cancellation constraints. It has high input and low output impedances; thus, it can be easily cascaded with other VM structures. It can be easily constructed by a single commercially available active element. Frequency-dependent non-ideal gain and parasitic impedance effects on the performance of the proposed PID controller are investigated. The performance of the proposed PID controller circuit is demonstrated by using PSPICE circuit simulation program and an experiment. Also, 0.18 μm CMOS TSMC technology parameters with ±2 V supply voltages are used. Total power dissipation of the proposed PID controller is 1.64 mW. [ABSTRACT FROM AUTHOR]

In this article, a new active building component with electronically tunable transresistive block, voltage difference transresistance amplifier, and its floating frequency dependent negative resistor simulator circuit application is presented. The simulator circuit is shown to operate using single active building block with two grounded passive components, to be electronically tunable over its value which is controlled by an independent current source, not to require any conditions of component matching and to have good sensitivity performance with respect to tracking errors. To examine functionality of the design, a CRD band-pass filter example is given. Numerous simulation program with integrated circuit emphasis (SPICE) simulations are performed and depicted through the article to verify validity of the study. Taiwan semiconductor manufacturing company (TSMC) 0.18 µm complementary metal oxide semiconductor technology parameters are used through simulations. [ABSTRACT FROM AUTHOR]

In this study, both current and transimpedance mode instrumentation amplification operations are met through a new active building block proposal, namely Current DifferencingTransresistance Amplifier block, CDTRA. In order to regard CDTRA as an instrumentation amplifier (IA), two grounded passive resistors are needed. Passive resistors together with electronically tunable transresistance parameter of active block, r m , set versatility over gain tunability for instrumentation amplifier. Proposed active block is current input, current/voltage output design. It has low impedance input, high impedance for current output, and low impedance for voltage output respectively. Since this particular IA is based on CDTRA, then it inherits these electrical characteristics fully. Numerous SPICE simulations are performed through the paper to verify validity of the study. TSMC 0.18 µm CMOS technology parameters are utilized through simulations. Experimental work is performed for the proposed IA circuit. [ABSTRACT FROM AUTHOR]

In this paper, new analog memristor emulator circuits based on current backward transconductance amplifier (CBTA) and passive elements are proposed. They emulate both types of memristor (incremental and decremental) just by interchanging the CBTA output terminals. It uses only one CBTA, two resistors, one capacitor and one multiplier emulating grounded memristor. They consist of less CMOS transistors and have wider output ranges compared to other designed emulator circuits. The CMOS implementation of the CBTA using 0.18 μm level-7 TSMC CMOS technology parameters is also proposed. It uses 23 CMOS transistors operating with the ±0.9 V DC supply voltage. Theoretical derivations and related results are validated using SPICE simulations. [ABSTRACT FROM AUTHOR]

The aim of this paper is proposing an alternative method to Gorski-Popiel Technique in realization of synthetic transformers. A new synthetic floating transformer (FT) circuit is also given. The proposed synthetic transformer circuit uses two current backward transconductance amplifiers (CBTAs), three resistors, and two grounded capacitors. The primary self-inductance, the secondary self-inductance, and the mutual inductance can be independently controlled and can be tuned electronically by changing the biasing current of the employed CBTAs. It has a good sensitivity performance with respect to tracking errors. A band-pass filter is also realized to test the performance of the proposed synthetic transformer circuit. The validity of the proposed synthetic transformer circuit is demonstrated by PSPICE simulations and experimental results. [ABSTRACT FROM AUTHOR]

[Display omitted] • Simple and low-cost system with high immunity against issues of standard optical transmission (vapor, fog). • Operation without significant path loss of the energy on very short distances for minimization of interferences with other services. • Bandwidth fitting low-frequency and biomedical applications (from sub-Hz to hundreds of Hz or slowly varying DC voltages). • Complete implementation of active parts in a form of Application Specific Integrated Circuit for low power consumption and. • Typical application example in monitoring of environmental features (temperature measurement). Infra-red (IR) and visible light (VL) based systems developed for transmission of information about physical quantities (e.g. humidity, temperature) out from closed areas, cannot be effectively employed in case of specific conditions in a targeted environment (because of fog or vapor for example). In this work, we introduce a concept of wireless short-range transmitter and receiver to sense physical quantities, for instance temperature, with slow variation. The proposed concept is able to transmit analog-based information from isolated environments (e.g. aquariums or environments for plant growing) with high immunity against vapor and fog that limits standard optical (laser, IR band) methods of communication. In this work, a new concept of short range radiofrequency (RF) communication device consisting of transmitting and receiving parts build from active devices fabricated in 0.35 μm I3T25 3.3 V CMOS process and ferrite antennas is selected. RF part uses medium-wave propagation within 10 mm distance at frequency 700 kHz. Such an approach offers minimal path loss of the radiated energy of a signal and low-gain amplification required for restoration of similar levels as available at the transmitting side. The processing of base-band signals of simple (sine wave) and complex (electrocardiogram) character was verified experimentally through the system. Application example of temperature monitoring in a closed environment, based on a temperature sensor (thermistor), verifies operationability in temperature range from 10 °C up to 50 °C. Compared to state-of-the-art solution, the presented concept has several advantages, for instance: less complexity; using of simpler type of modulation and demodulation; lower power consumption and significantly reduced issues caused by an environment with special transmission conditions (e.g. fog and vapor). The obtained results are in good agreement with expectations. Among others, the presented system brings beneficial performances for similar applications targeting on monitoring of low-frequency or slowly varying signals. [ABSTRACT FROM AUTHOR]

Diffuse optical tomography (DOT) is an optical imaging technique using near-infrared spectroscopy (NIRS). Because the NIR light is highly scattered in biological tissue, the photon density drops rapidly with increasing depth. This makes the measurement accuracy of DOT in deep tissue significantly lower than in superficial tissue. Classical Regularized Least Square (RLS) based regularization methods with different penalty term (l1-norm, l2-norm, LASSO, Ridge, and Elastic Net etc.) come up short in finding the inclusions when the inclusion number is increased or one of the inclusion located on the upper surface and the other one located on the deeper surface of the tissue. This is the depth problem encountered in DOT. In this paper, a new least square based regularization method is proposed. Within the scope of the proposed method, both the weight matrix and penalty terms are modified in order to solve this problem. In this process, firstly, the A matrix is changed using the diagonal value of A A T based on DCA (Depth Compensation Algorithm). Then, a new penalty term using modified A matrix is added. It has been observed that when the noise level increases, proposed method give higher accuracy and more robust according to other RLS Method on synthetic data. Experimental results on synthetic data show that the new method improves inversion accuracy, reduces errors, and the lowers inversion instability compared to the state-of-the-art methods. [ABSTRACT FROM AUTHOR]

In this study, a novel lead and lag type compensator circuit is proposed using a single active component, namely, the current feedback operational amplifier (CFOA). The proposed circuit has only one CFOA, two grounded resistors and two grounded capacitors. The input impedance of the proposed compensator is designed to be high whereas the output impedance is low. In terms of input and output impedance values, the proposed topology is suitable for a cascade connection with the voltage-mode structure not requiring buffer circuits, both at the input and output of the circuit. Moreover, the proposed circuit offers the advantage of controlling the poles and zeros orthogonally. The non-ideal effects depending on the active component are also presented in the paper. The commercially available AD844 integrated circuit component was used as the CFOA component in the proposed lead and lag compensator circuit and circuit simulations were performed using PSpice. Moreover, the electrical performance of the circuit was demonstrated by experimental studies. The achieved theoretical, simulation and experimental results are given with a comparison. Finally, a closed-loop control system application was given using the proposed compensator circuit and the operation of the circuit was demonstrated with PSpice simulations. [ABSTRACT FROM AUTHOR]

In this work, a CBTA-based universal mutator circuit is proposed for the realization of memcapacitor and meminductor elements. Proposed mutator circuit contains only one CBTA element, one memristor and one capacitor. It is suitable to transform a grounded memristor to a floating memcapacitor or meminductor. SPICE simulation by using a CBTA designed with 0.18 μm level-7 TSMC CMOS transistors was performed to show the accuracy of the proposed circuit and as a result, frequency dependent hysteresis loops are obtained. [ABSTRACT FROM AUTHOR]

In this study, patient monitoring system which enables instant recording the data from biomedical sensor (ECG, heart rate, temperature, movement, etc.) is developed. The main structures of the proposed system consist of biomedical sensors, ATmega microcontroller and IEEE 802.11 Wi-Fi module. The signals, obtained from the biomedical sensors, converted to digital data and transferred to the server by the Wi-Fi module. In this way, the biomedical data's are delivered to the medical staffs that are connected to the system with mobile and desktop devices. Moreover, in case of emergency the system could alert the relevant departments with embedded systems and server software. [ABSTRACT FROM AUTHOR]

Objective: Myelin is essential for a healthy nervous system. Myelin formed by oligodendrocytes, accelerates impulse propagation and supports neuronal survival. Demyelination leads to neurodegeneration. In multiple sclerosis (MS) immune attack results in demyelination. Our goal is to dissect interactions among oligodendrocytes, neurons, and immune cells to improve our understanding of myelination and the demyelinating diseases. We aim to discover new targets for remyelination therapies. Methods: We are building tools for analyzing protein-protein and cell-to-cell interactions. To identify genes involved in myelination and MS, we developed a bioinformatics-based strategy, interactome analysis, which combines proteome and gene expression methodologies. Identified genes are evaluated in peripheral blood of MS patients and in mouse models. To accelerate drug discovery, 23 machine learning-based methodologies were assessed for myelin identification in fluorescent microscopy images. Results: Interactome analysis identified hundreds of proteinprotein interactions between pairs of oligodendrocytes, neurons, macrophages, microglia, and T cells. Most significant interactions are further analyzed in vivo and in vitro. Our customizedconvolutional neural network and Boosted Tree methods segmented myelin at over 98% accuracy. Identified myelin can be quantified and visualized in 3D. Conclusion: The interactome analysis yielded novel genes that are likely to be linked to MS. Machine learning-based methodologies are very effective in accelerating myelin quantification and thus, drug screens against demyelinating diseases such as MS. Overall, our innovative analysis strategies employing computer assistance produced novel avenues of exploration for myelination and demyelinating diseases. This study was supported TUBITAK (218S495,316S026), Istanbul Medipol University (BAP2018/06), and Turkish Academy of Sciences (GEBIP). [ABSTRACT FROM AUTHOR]