Circuit Modification Research Articles

Inhibition gates supralinear Ca2+ signaling in Purkinje cell dendrites during practiced movements.

Motor learning involves neural circuit modifications in the cerebellar cortex, likely through re-weighting of parallel fiber inputs onto Purkinje cells (PCs). Climbing fibers instruct these synaptic modifications when they excite PCs in conjunction with parallel fiber activity, a pairing that enhances climbing fiber-evoked Ca2+ signaling in PC dendrites. In vivo, climbing fibers spike continuously, including during movements when parallel fibers are simultaneously conveying sensorimotor information to PCs. Whether parallel fiber activity enhances climbing fiber Ca2+ signaling during motor behaviors is unknown. In mice, we found that inhibitory molecular layer interneurons (MLIs), activated by parallel fibers during practiced movements, suppressed parallel fiber enhancement of climbing fiber Ca2+ signaling in PCs. Similar results were obtained in acute slices for brief parallel fiber stimuli. Interestingly, more prolonged parallel fiber excitation revealed latent supralinear Ca2+ signaling. Therefore, the balance of parallel fiber and MLI input onto PCs regulates concomitant climbing fiber Ca2+ signaling.

SAP102 regulates synaptic AMPAR function through a CNIH-2-dependent mechanism.

The postsynaptic density (PSD)-95-like, disk-large (DLG) membrane-associated guanylate kinase (PSD/DLG-MAGUK) family of proteins scaffold α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) complexes to the postsynaptic compartment and are postulated to orchestrate activity-dependent modulation of synaptic AMPAR functions. SAP102 is a key member of this family, present from early development, before PSD-95 and PSD-93, and throughout life. Here we investigate the role of SAP102 in synaptic transmission using a cell-restricted molecular replacement strategy, where SAP102 is expressed against the background of acute knockdown of endogenous PSD-95. We show that SAP102 rescues the decrease of AMPAR-mediated evoked excitatory postsynaptic currents (AMPAR eEPSCs) and AMPAR miniature EPSC (AMPAR mEPSC) frequency caused by acute knockdown of PSD-95. Further analysis of the mini events revealed that PSD-95-to-SAP102 replacement but not direct manipulation of PSD-95 increases the AMPAR mEPSC decay time. SAP102-mediated rescue of AMPAR eEPSCs requires AMPAR auxiliary subunit cornichon-2, whereas cornichon-2 knockdown did not affect PSD-95-mediated regulation of AMPAR eEPSC. Combining these observations, our data elucidate that PSD-95 and SAP102 differentially influence basic synaptic properties and synaptic current kinetics potentially via different AMPAR auxiliary subunits. NEW & NOTEWORTHY Synaptic scaffold proteins postsynaptic density (PSD)-95-like, disk-large (DLG) membrane-associated guanylate kinase (PSD-MAGUKs) regulate synaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) function. However, the functional diversity among different PSD-MAGUKs remains to be categorized. We show that distinct from PSD-95, SAP102 increase the AMPAR synaptic current decay time, and the effect of SAP102 on synaptic AMPAR function requires the AMPAR auxiliary subunit cornichon-2. Our data suggest that PSD-MAGUKs target and modulate different AMPAR complexes to exert specific experience-dependent modification of the excitatory circuit.

(Invited) Technology Breakthrough by Ferroelectric HfO2 for Low Power Logic and Memory Applications

In today’s highly information-oriented society, more and more electronic devices are needed for high-end servers in cloud and sensor node devices in edge. Because of the power constraint, highly energy-efficient computing is required, which new transistor and memory technologies enable [1]. As a general guideline for energy-efficient computing, higher Ion/Ioff at lower supply voltage is obtained by using steep subthreshold slope (SS) transistor, and normally-off operation is performed without much overhead by using non-volatile memory. Those logic and memory technologies must be developed at low cost. Recent discovery of ferroelectric (FE) HfO2 [2] will realize low-cost and energy-efficient logic and memory devices. In this paper, the recent status of negative capacitance FET (NCFET), non-volatile SRAM (NV-SRAM), and FE tunnel junction memory (FTJ), all of which are based on FE-HfO2, will be overviewed. NCFET is the transistor which has ferroelectric gate insulator and uses negative capacitance to amplify surface potential. It has been regarded as one of the most promising steep SS transistors because of (1) high Ion/Ioff ratio with high Ion, (2) CMOS process compatibility, and (3) minimum circuit modification, with the use of FE-HfO2 at low cost. Device design guideline revealed that NCFET can operate at as low as 0.2V supply voltage [3]. Moreover, NCFET gate stack material can fit to advanced CMOS process with replacement gate FinFET [4] and Nanowire [5]. In recent years, there were encouraging experimental demonstrations of steep SS in long and short channel devices. Operation speed of NCFET may be limited by the dynamics of atomic displacement and domain dynamics [3,6], which is one of the central topics. NC effect is regarded as an additive performance booster and expected to synthesize with novel channel material and other steep SS transistors such as TFET [7]. IoT sensor node devices are expected to operate in an intermittent mode. The active rate of a transistor is much lower than clock frequency in IoT device. In order to suppress standby leakage power, especially in SRAM, it is important to bring the transistors in sleep mode as much as possible [1]. Normally-off computing is the idea that stores the current state data in NV memory and restore the data after wake-up without much latency and power overhead. NV-SRAM has been revisited by using FE-HfO2 which realizes good scalability as well as cost effective process [8]. NV-SRAM has been recently designed, fabricated by integrating FE-HfO2 capacitor in back-end process, and characterized. Store, power-off, and recall operation are successfully demonstrated. New AI algorithms such as deep learning have made big impacts in business, however, it requires enormous amount of computing power. In order to use such algorithm in edge devices, energy efficiency should be greatly improved and hardware implementation of such algorithm will be highly required. Recently, artificial neural network (ANN) has been realized by using synaptic device such as resistive change RAM (ReRAM) as nonvolatile analog memory. FE memory is also the alternative for synaptic device. FTJ is an emerging memory cell which utilizes polarization switching to change on-sate and off-state tunneling electroresistance (TER) . FTJ has been recently demonstrated by using FE-HfO2 with as high TER as >30 and multi-level cell operation [9]. Linearity and reliability should be further examined for ANN applications.

Fluorescent Guide RNAs Facilitate Development of Layered Pol II-Driven CRISPR Circuits.

Efficient clustered regularly interspaced short palindromic repeat (CRISPR) guide RNA (gRNA) expression from RNA Polymerase II (Pol II) promoters will aid in construction of complex CRISPR-based synthetic gene networks. Yet, we require tools to properly visualize gRNA directly to quantitatively study the corresponding network behavior. To address this need, we employed a fluorescent gRNA (fgRNA) to visualize synthetic CRISPR network dynamics without affecting gRNA functionality. We show that studying gRNA dynamics directly enables circuit modification and improvement of network function in Pol II-driven CRISPR circuits. This approach generates information necessary for optimizing the overall function of these networks and provides insight into the hurdles remaining in Pol II-regulated gRNA expression.

Note: Space qualified solid state photon counting detector with reduced detection delay temperature drift.

The solid state photon counting detector is one of the key components of a measurement chain for laser time transfer ground to space. The photon counting approach significantly reduces systematic errors of the time transfer. The requirements put on the detection precision and the stability of laser time transfer are increasing and reaching sub-picosecond levels now. The temperature variations in the space environment limit the long term detection delay stability of detectors. Therefore, we have modified the existing space qualified solid state photon counter control circuit which compensates to a high degree the temperature variations of detection delay. We have optimized the detection delay change with operating temperature and reached the lowest temperature coefficient as low as 20 fs/K in a temperature range of +22 to +46 °C. The timing resolution and photon detection probability remained unchanged at the values of 40 ps FWHM and 30%, respectively. Thanks to the low temperature drift of the detector, the limiting precision of the laser time transfer chain characterized by time deviation is lower than 40 fs for 2000 s averaging time. These detection delay stability parameters are, to our knowledge, the best ever reported for any photon counting detector. This modification of the detector control circuit did not affect the space qualification of the device, which is expected to be used in future laser time transfer space missions.

Circuit modification and research of operation modes of high-frequency pulsed resonant converter of the X-ray tube power supply

Despite obvious drawbacks of the resonant converter, such as complicated calculation, increased size and weight of the device, deviations of the circuit parameters from product to product, the resonant converter shows significant advantages in comparison with other. The task was to design the generator, which is built on a resonant topology.

Strategies for Prevention and Management of Bleeding Following Pediatric Cardiac Surgery on Cardiopulmonary Bypass: A Scoping Review.

We aimed to systematically describe, via a scoping review, the literature reporting strategies for prevention and management of mediastinal bleeding post pediatric cardiopulmonary bypass surgery. MEDLINE, EMBASE, PubMed, and Cochrane CENTRAL Register. Two authors independently screened publications from 1980 to 2016 reporting the effect of therapeutic interventions on bleeding-related postoperative outcomes, including mediastinal drain loss, transfusion, chest re-exploration rate, and coagulation variables. Inclusions: less than 18 years, cardiac surgery on cardiopulmonary bypass. Data from eligible studies were extracted using a standard data collection sheet. Overall, 299 of 7,434 screened articles were included, with observational studies being almost twice as common (n = 187, 63%) than controlled trials (n = 112, 38%). The most frequently evaluated interventions were antifibrinolytic drugs (75 studies, 25%), blood products (59 studies, 20%), point-of-care testing (47 studies, 16%), and cardiopulmonary bypass circuit modifications (46 studies, 15%). The publication rate for controlled trials remained constant over time (4-6/yr); however, trials were small (median participants, 51; interquartile range, 57) and overwhelmingly single center (98%). Controlled trials originated from 22 countries, with the United States, India, and Germany accounting for 50%. The commonest outcomes were mediastinal blood loss and transfusion requirements; however, these were defined inconsistently (blood loss being reported over nine different time periods). The majority of trials were aimed at bleeding prevention (98%) rather than treatment (10%), nine studies assessed both. Overall, this review demonstrates small trial sizes, low level of evidence, and marked heterogeneity of reported endpoints in the included studies. The need for more, higher quality studies reporting clinically relevant, comparable outcomes is highlighted. Emerging fields such as the use of coagulation factor concentrates, goal-directed guidelines, and anti-inflammatory therapies appear to be of particular interest. This scoping review can potentially guide future trial design and form the basis for therapy-specific systematic reviews.

A Modified Series-Capacitor High Conversion Ratio DC–DC Converter Eliminating Start-Up Voltage Stress Problem

In this letter, a modified series-capacitor (SC) high conversion ratio (HCR) dc–dc converter is proposed. The proposed converter inherits most of the advantages of the existing SC HCR dc–dc converter and can eliminate the problem of high switch-voltage stress of the existing converter encountered during start-up using a simple circuit modification. Although an extra capacitor is required in the proposed converter, total series capacitance of the proposed converter is the same as that of the conventional SC converter. In addition, input capacitance of the proposed converter can be reduced by less than half of that of the SC buck converter. A 1-kW prototype converter is built and tested to verify the performance of the proposed converter.

CRRT in critically Ill children: Clinical profile from a tertiary care hospital in South India

Background : Continuous renal replacement therapy (CRRT) is a valuable tool in a pediatric intensive care unit (PICU), however the literature available from developing countries is scarce. Methods : Retrospective analysis of children who underwent CRRT during the past 1 year (June 2016 to May 2017). 24 sessions of CRRT was performed in 22 patients using Prismaflex® Baxter. Serum levels of urea, creatinine, and liver function tests were done in all patients. Activated clotting time (ACT) was monitored in all patients every 1 hourly till target ACT was achieved (180 – 220 seconds), thereafter every 4 hourly if the ACT continues in the target range. Unfractionated heparin was used for anticoagulation. Blood priming was done in patients with hematocrit less than 30% or in infants weighing less than 10 kg. Hemodialysis catheter (8.5Fr) was used in all patients, placed in the right internal jugular vein (IJV) under ultrasound guidance. Transthoracic echocardiography was used in all patients to confirm the position of the catheter tip within the right atrium. Central venous access in the femoral vein and arterial blood pressure monitoring was done in all patients as per unit protocol. Primary outcome measure was death during the procedure. Data collected were part of PRBC transfusion in pediatric ICU study and fluid balance study at JIPMER. Results : The median age of patients was 2 years (1 to 6 IQR). Mean bodyweight was 13.4 kg, 6.6 SD. Continuous venovenous hemofiltration (CVVH) was done in 5 patients (22.7%) and 17 patients (67.3%) were started on continuous venovenous hemodiafiltration (CVVHDF). Mortality during the procedure among the patients who underwent CRRT was 50% (n=11). Mean PRISM III score was 14. Out of 22 patients, 15 patients (68.7%) were on vasoactive medications at the time of initiation of CRRT. Median fluid overload (FO%) was 0.62 (0.45 to 1.62 IQR). Average time to start CRRT since PICU admission was 55 hours. The common indications were acute kidney injury with fluid overload (n=9), acute liver failure with hyperammonemia (n=3), organic acidemia with severe high anion gap acidosis (n=1), unknown poisoning with high anion gap acidosis (n=2), pigment nephropathy following wasp sting (n=1) and electrocution (n=1). CRRT along with venovenous extra corporeal membrane oxygenation (vv ECMO) (n=1) was done in a case of hemophagolymphohistiocytosis syndrome with ARDS. Effluent dose 35ml/kg/hour in all patients except in 2 cases of acute liver failure where the effluent dose was increased up to 42ml/kg/hour due to persistent hyperammonemia. CRRT with plasma exchange using P2 plasma filter was done with CRRT circuit modification in 2 cases of thrombocytopenia associated multiorgan failure (TAMOF). Mean duration of CRRT was (55 hours, SD 23.8). Maximum circuit life with systemic heparin as anticoagulant was 92 hours. Filter clotting and new circuit requirement was encountered in 6 patients (27.7%). Conclusion : CRRT can be used safely in critically ill children. The circuit life can be prolonged with serial ACT monitoring and titration of anticoagulation.

Novel CMOS Dual-X Current Conveyor Transconductance Amplifier Realization with Current-Mode Multifunction Filter and Quadrature Oscillator

This paper presents a novel active element, namely dual-X current conveyor transconductance amplifier. The CMOS implementation, parasitic model and characteristic performance parameters of the proposed dual-X current conveyor transconductance amplifier have been explored. The proposed active element has the advantages of good operational bandwidth, good dynamic range and low power consumption. Additionally, current-mode multifunction filter and quadrature oscillator are proposed to examine the applicability of the newly proposed active element. The proposed current-mode multifunction filter provides the responses, low-pass, high-pass and band-pass simultaneously without any circuit modification. The proposed quadrature oscillator circuit simultaneously generates three current outputs and three voltage outputs. The non-ideal analyses of both current-mode multifunction filter and quadrature oscillator are also included. Moreover, the active and passive sensitivities of both current-mode multifunction filter and quadrature oscillator are calculated which are found to be less than unity in magnitude. HSPICE simulation results are depicted to confirm the theoretical analyses. Moreover, practicality of novel dual-X current conveyor transconductance amplifier is examined through the experimental results of the proposed quadrature oscillator.

Modofication of the Sarcheshmeh copper complex flotation circuit in response to a reduction in feed grade

The new copper processing plant of the Sarcheshmeh copper complex consists of two parallel circuits. After a primary crushing, the ore is sent to a SAG mill, and the product is further ground in a ball mill. The overflow of the hydrocyclones is fed to a flotation circuit that contains 8 rougher tank cells (RCS130), 3 cleaner cells (RCS50), 5 scavenger cells (RCS50), and a flotation column (as recleaner). The circuit was initially designed to process a feed containing 0.8% Cu but due to a change in the ore type, the feed grade decreased to 0.6% Cu. This resulted in a reduction in the final concentrate grade and the recovery from 28% and 85.5% to 24% and 84.4%, respectively. Based on the original design, the copper and silica recovery in the cleaner cells should be 69% and 55%, respectively, but these values increased to 85% and 75% due to a higher retention time. The rather high silica recovery was found to be the main source of the lower final concentrate grade. In order to reduce the retention time of particles in the cleaner cell from 13.7 to 6.9 min, the rougher concentrates of two parallel circuits were fed to only one cleaner-scavenger and regrind circuit. This modification increased the cleaner and final concentrate grade from 15.1% and 24.5% to 17% and 26%, respectively. The overall outcome of the circuit modification was evaluated to be a 10% reduction in the energy consumption without any loss in the overall copper recovery.

Circuit simulation assisting Physical Fault Isolation for effective root cause analysis

In this study, the PFI (Physical Fault Isolation) was assisted with the analog circuit simulation to provide insight into the device performance under the failed condition and the failure mechanisms. This approach allows us to choose and apply the right PFI technique to find the failure root cause in a very time effective manner and propose the failure mode hypothesis. Accordingly, as an alternative to the conventional circuit modification approaches a backside PLS (Photoelectric Laser Stimulation) based technique was applied to the suspicious analog block. In this technique, a laser with the wavelength in the NIR (Near Infrared) range stimulates the analog circuit block at the transistor level and changes the device electrical state from fail to pass. Consequently, we could evaluate the circuit behaviour at failed condition and verify the failure. In this manner, the competent combination of PFI and analog circuit simulation successfully leads us to the corrective action to improve the circuit design and overcome the inevitable fabrication process variation.

Dynamic Performance Improvement of Diode–capacitor-Based High Step-up DC–DC Converter Through Right-Half-Plane Zero Elimination

Diode–capacitor-based dc–dc converters provide a simple and low cost solution for high step-up voltage regulation in solar and fuel cell generation. Transient modeling analysis reveals their worse influence of nonlinear and nonminimum-phase system characteristic due to right-half-plane (RHP) zero, especially in high voltage gain application. However, the process of energy transfer for diode–capacitor-based dc–dc converter is different from basic dc–dc converter. Based on the unique feature, this paper proposes an improved main circuit structure with parallel connection of resistive–capacitive damping network across the intermediate capacitor to achieve good dynamic performance. By optimal parameter design according to Routh–Hurtwitz criterion, all the RHP zeros in the transfer function of control-to-output voltage are eliminated completely. Then, by the case of diode–capacitor-based boost converter, the adaptive PI controller is designed to deal with nonlinear characteristic of voltage gain. It gets good dynamic performance under wide range output voltage. All the theoretical findings and design approaches are verified by simulation and experiment results. The existing diode–capacitor-based high step-up dc–dc converters with slight main circuit modification are more promising in renewable energy application.

Magnetic circuit modifications in resonant vibration harvesters

Abstract The paper discusses the conclusions obtained from a research centered on a vibration-powered milli- or micro generator (MG) operating as a harvester to yield the maximum amount of energy transferred by the vibration of an independent system. The investigation expands on the results proposed within papers that theoretically define the properties characterizing the basic configurations of a generator based on applied Faraday’s law of induction. We compared two basic principles of circuit closing in a magnetic circuit that, fully or partially, utilizes a ferromagnetic material, and a large number of generator design solutions were examined and tested. In the given context, the article brings a compact survey of the rules facilitating energy transformation and the designing of harvesters.

A short survey on nonlinear models of QPSK Costas loop

The Costas loop is a modification of the phase-locked loop circuit, which demodulates data and recovers carrier from the input signal. The Costas loop is essentially a nonlinear control system and its nonlinear analysis is a challenging task. Thus, simplified mathematical models and their numerical simulation are widely used for its analysis. At the same time for phase-locked loop circuits there are known various examples where the results of such simplified analysis are differ substantially from the real behavior of the circuit. In this survey the corresponding problems are demonstrated and discussed for the QPSK Costas loop.

COMEDI: Combinatorial Election of Diagnostic Vectors From Detection Test Sets for Logic Circuits

Although the modern automatic test pattern generation (ATPG) tools can efficiently produce near-optimal test sets with high fault-coverage for a circuit-under-test, a diagnostic test set (DTS), which is needed for fault localization, is much more challenging to construct. The DTS is used to analyze the responses of failing chips during manufacturing test for the purpose of identifying the root cause of observed errors. In this paper, a novel technique for selecting a powerful DTS for stuck-at faults from a pool of ATPG detection vectors is proposed. Unlike existing methods, this technique does not use any diagnostic test generation, circuit modification, or miter-based approach. It constructs a combinatorial cover of the pool to determine a test set with high diagnostic coverage (DC). Two variants of the covering algorithm are proposed based on this technique. The experimental results on several combinational and scan-based benchmark circuits demonstrate the effectiveness of our method in terms of the size of the DTS, DC, and CPU time.

CREATION OF ENERGY SAVING PROGRAM FOR POWER SUPPLY SYSTEMS

The article discusses a new approach to the formation of energy–saving program for the power supply system, which aims to realize the maximum amount of reserve electric power saving system. The combination of all technical and circuit modifications at each site and system level power that creates the energy–efficient systems, and is an initial list of energy saving measures will be included into the program. The general list of energy–saving measures on the results of the program to optimize the structure and parameters of the system in terms of the minimum electric power losses in it is formed. For the power supply system on the basis of a regulatory evaluation of the effectiveness of energy saving measures it is proposed the criteria selection of cost–effective measures to reduce energy losses in the system: the saved energy cost should not exceed the current tariff for electricity consumption from the grid

Enhancement of pumping efficiency of a CuBr laser by means of modification of the discharge circuit

Enhancement of pumping efficiency of a CuBr laser by means of modification of the discharge circuit

Modification of feeding circuits in the evolution of social behavior.

Adaptive trade-offs between foraging and social behavior intuitively explain many aspects of individual decision-making. Given the intimate connection between social behavior and feeding/foraging at the behavioral level, we propose that social behaviors are linked to foraging on a mechanistic level, and that modifications of feeding circuits are crucial in the evolution of complex social behaviors. In this Review, we first highlight the overlap between mechanisms underlying foraging and parental care and then expand this argument to consider the manipulation of feeding-related pathways in the evolution of other complex social behaviors. We include examples from diverse taxa to highlight that the independent evolution of complex social behaviors is a variation on the theme of feeding circuit modification.

Compact High-Efficiency Li-Ion Fast-Charger

This contribution presents improvements of the flyback converter topology to be used in a 600 Watt compact, light-weight and high-efficiency Li-Ion battery charger. The improved flyback converter, utilizing modern components (e.g. SiC semiconductors) and circuit modifications, is used in place of the standard forward converter with great results. Total efficiency of the charger of over 93 % is possible. The charger is controlled by an MCU which takes information from an external BMS. Low standby consumption (<0.5 W) is assured.