A New Efficient Technique for Solving Modified Chua's Circuit Model with a New Fractional Operator

Chua's circuit is an electronic circuit that exhibits nonlinear dynamics. In this paper, a new model for Chua's circuit is obtained by transforming the classical model of Chua's circuit into novel forms of various fractional derivatives. The new obtained system is then named fractional Chua's circuit model. The modified system is then analyzed by the optimal perturbation iteration method. Illustrations are given to show the applicability of the algorithms, and effective graphics are sketched for comparison purposes of the newly introduced fractional operatorsThe authors are grateful to the Spanish Government for Grant RTI2018-094336-B-I00 (MCIU/AEI/FEDER, UE) and to the Basque Government for Grant IT1207-1

The effects of vardenafil and pentoxifylline administration in an animal model of ischemic colitis

OBJECTIVES: Vardenafil enhances dilatation of vascular smooth muscle and inhibits platelet aggregation. The purpose of this study was to evaluate the clinical effects of vardenafil and pentoxifylline administration in an experimental model of ischemic colitis. METHODS: Forty female Wistar albino rats weighing 250-300 g were randomized into five experimental groups (each with n = 8) as follows:1) a sham group subjected to a sham surgical procedure and administered only tap water; 2) a control group subjected to a standardized surgical procedure to induce ischemic colitis and administered only tap water; 3) and 4) treatment groups subjected to surgical induction of ischemic colitis followed by the postoperative administration of 5 mg/kg or 10 mg/kg vardenafil, respectively; and 5) a treatment group subjected to surgical induction of ischemic colitis followed by postoperative administration of pentoxifylline at 50 mg/kg/day per day as a single dose for a 3-day period. All animals were sacrificed at 72 h post-surgery and subjected to relaparotomy. We scored the macroscopically visible damage, measured the ischemic area and scored histopathology to determine the severity of ischemia. Tissue malondialdehyde levels were also quantified. RESULTS: The mean Gomella ischemic areas were 63.3 mm2 in the control group; 3.4 and 9.6 mm2 in the vardenafil 5 and vardenafil 10 groups, respectively; and 3.4 mm2 in the pentoxifylline group (p = 0.0001). The mean malondialdehyde values were 63.7 nmol/g in the control group; 25.3 and 25.6 nmol/g in the vardenafil 5 and vardenafil 10 groups, respectively; and 22.8 nmol/g in the pentoxifylline group (p = 0.0001). CONCLUSION: Our findings indicate that vardenafil and pentoxifylline are effective treatment options in an animal model of ischemic colitis. The positive clinical effects produced by these drugs are likely due to their influence on the hemodynamics associated with vascular smooth muscle and platelet functions

Fitness Medicine

Although fitness and health have similar properties, they are, in reality, two very different concepts. While health refers to the absence of diseases, fitness refers to the degree of body functioning and the ability of the body to handle physical demands. The more efficient the body functions, the higher the level of fitness. The higher the level of fitness, the greater the chance of the body being free of diseases and maintaining a healthy state

The Effect of Volleyball Training on the Physical Fitness of High School Students

AbstractThe aim of this study is to determine the effect of regularly applied volleyball training on the physical fitness values of High School students. A total of 62 students from three different high schools participated in the study. The students who participated in the study were divided into two different groups; one group consisted of those who did not join in any sporting activities except for the physical education classes at school while the other group consisted of those who played in the school volleyball team in addition to the physical education classes at school. Eight tests were used derived from the EUROFIT test: flamingo, plate tapping, sit and reach, standing broad jump, handgrip, sit-ups, bent arm hang and 10 x 5m shuttle-run tests to determine the physical fitness of the students. The data obtained were interpreted using the SPSS 14.0 packet program

A Novel Floating/Grounded Meminductor Emulator

Meminductor is a nonlinear two-terminal element with storage energy and memory ability. To date, meminductor element is not available commercially as memristor and memcapacitor are. Therefore, it is of great significance to implement a meminductor emulator for breadboard experiment. In this paper, a flux-controlled floating/grounded meminductor emulator without a memristor is presented. It is built with commercially available off-the-shelf electronic devices. It consists of single operational transconductance amplifier (OTA), single multiplier, two second-generation current conveyors (CCIIs), single current-feedback operational amplifier (CFOA) and single operational amplifier. Using OTA device introduces an additional control parameter besides frequency and amplitude values of applied voltage to control the area of pinched hysteresis loop of meminductor. Mathematical model of proposed emulator circuit is given to describe the behavior of meminductor circuit. The breadboard experiment is performed using CA3080, AD844, AD633J and LM741 for OTA, CCII-CFOA, multiplier and operational amplifier, respectively. Simulation and experimental test results are given to verify the theoretical analyses. Frequency-dependent pinched hysteresis loop is maintained up to 5 kHz. The presented meminductor emulator tends to work as ordinary inductor for higher frequencies

On The Realization of Memristor Based RC High Pass Filter

In 1971, Prof. Leon Chua proposed and described memristor which defines the relationship between flux and charge. Stanley Williams and his group realized a practical device that fulfills the memristor properties. In this paper, a memristor based high pass filter is presented. A comparative analysis between resistor and memristor based high pass filters is performed. The cut off frequency dependency of the high pass filter with memristor configuration is investigated. SPICE simulation results which are obtained using a memristor SPICE model with nonlinear dopant drift are included to verify theoretical analyses. The effect of change in the input frequency and initial condition of the length of doped region on the cut off frequency of the given high pass filter is investigated. The memory effect of memristor is represented by simulation results

NEW MEMRISTOR EMULATOR CIRCUIT USING OTAs AND CCIIs

In this paper, a new memristor emulator circuit is proposed. It is realized by operational transconductance amplifiers (OTAs) and second generation current conveyors (CCIIs). A mathematical model to describe the behavior of presented circuit is derived. Memristance value of the emulator circuit is adjustable by means of a simple change of transconductance parameter (g(m)) of operational transconductance amplifier in the emulator circuit, amplitude and frequency value of applied voltage across terminals of memristor emulator. Frequency dependent pinched hysteresis loop in the current versus voltage plane holds up to 5 kHz. The breadboard experiment of proposed emulator circuit is built by using CA3080 and AD844 ICs for transconductance amplifier and second generation current conveyor respectively. The results of SPICE simulation and experimental test are given to verify the theoretical analyses. The presented emulator circuit can be used in real world memristor circuit applications such as chaotic systems, programmable analog circuits

Electronically tunable memristor emulator circuit

In this paper, memristor emulator circuit which is built with off the shelf electronic devices is presented. It consists of three operational transconductance amplifiers (OTA) and four second generation current conveyors (CCII). Using OTA offers an extra control parameter, operational transconductance parameter (g(m)), in addition to frequency (f) and amplitude value of voltage across emulator (v (m) ). Since g(m) is proportional to current flowing through the bias terminal of OTA, it is possible to change the memristance variation via a simple change of amplitude value. Since g(m) parameter is adjustable via an external dc voltage/current source, the memristance of presented emulator circuit is electronically tuneable. Mathematical model is derived to characterize the behaviour of the emulator circuit. Frequency analysis is performed to determine how to maintain the pinched hysteresis loop at high frequencies. The presented emulator circuit is simulated with SPICE simulation program. The breadboard experiment of emulator circuit is built using CA3080 and AD844 ICs for OTA and CCII devices respectively. Frequency dependent pinched hysteresis loop in the current versus voltage plane holds up to 10 kHz. Mathematical model and theoretical analyses show a good agreement with SPICE simulation and experimental test results

FIRST-ORDER MEMRISTOR-CAPACITOR FILTER CIRCUITS EMPLOYING HP MEMRISTOR

The memristor has drawn the worldwide attention since it has been discovered at HP laboratory on 1 May 2008. Since then many researchers are taking efforts to find its applications in various areas. In this paper, we study the filter characteristics of first-order low pass and high pass filters employing memristor with a capacitor. The paper provides a comparative analysis between low pass and high pass filter circuits that utilizing ordinary resistor or memristor with a capacitor. The theoretical analyzes are verified with SPICE simulation results using a memristor SPICE model with nonlinear dopant drift and MATLAB environment. The effect of change of the input frequency and initial resistance value of memristor on the cut-off frequencies of the presented low pass and high pass filters are investigated. The memory effect of memristor is represented by simulation results

Comparison of Estimated and Real COVID-19 Cases and Deaths for 45 Days

The Coronavirus Disease 2019 (COVID-19) is caused by the new type of coronavirus, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), emerged in China at the end of 2019, and spread all over the world in a very short time. The World Health Organization (WHO) declared COVID-19 a global pandemic due to its rapid spread and lack of effective vaccination, immunization and treatment. In this study, we aimed to make a retrospective evaluation of forty-five days of COVID-19 cases and deaths simulated by the modified mathematical model which was previously established and published by us. 30 days and 45 days of COVID-19 cases and deaths which were estimated by our modified mathematical model were compared to the real cases and deaths in Turkey since 15.03.2020. The COVID-19 cases increased to a significant level on 20.03.2020 in Turkey. The modified mathematical modeling results’ estimation accuracy remained above 90% until 13.04.2020. This rate was 78.40% on 28.04.2020. The modified mathematical modeling estimation for the COVID-19 deaths started on 20.03.2020 because the number of deaths were then significant enough for estimation with the modified mathematical model. The estimation accuracy for the number of deaths was 100% with a value of 37 on 23 March 2020, and after that, it had always remained above 90% until 13.04.2020. Finally, it was 66.08% on 28.04 2020. The estimation accuracies of the modified mathematical model about the COVID-19 cases in Turkey for 30 days and 45 days were above 90% and 78% respectively. The estimation accuracies of the modified mathematical model about the COVID-19 deaths in Turkey for the 30-day and 45-day periods were above 90% and 66%, respectively. This result suggests that the modified mathematical model is available for estimating the course of disease outbreaks and pandemics. The model should be developed through future studies, which will improve its estimation accuracy