External Electromagnetic Signal Research Articles

Elimination of CM Noise from SMPS Circuit using EMI Filter

The electronic devices are exposed to external electromagnetic signals that produce an unwanted signal called noise in the circuit, which causes electromagnetic interference [EMI] problems. It occurs in two modes: radiated mode and conducted mode. In the radiation mode, the shielding technique is used for radiation mode, in conduction mode filtering technique is used. The design of an EMI filter depends upon the type of noise generated by the Switched Mode Power supply circuit [SMPS]. The SMPS circuit used in this paper is a DC-DC power converter, the Boost converter is a step-up converter and Buck converter is step down converter are considered as equipment for generation of noise, the Line Impedance Stabilization Network [LISN]is used for generating the common output impedance to the power converters, the EMI filters are designed to eliminate noise generated by the circuits. There noise generated by this power converters is Common Mode [CM] noise and Differential Mode [DM] noise. The separation of noise from the equipment is done by using a noise separator. In this paper, CM noise generated by these power converters is eliminated by designing an EMI filter called an inductor filter and a PI filter. The comparison between the LC inductor filter and the PI filter for the boost and buck converters is observed. The PI filter has better performance characteristics when compared to the inductor filter for both SMPS circuits as per the Comité International Special des Perturbations Radioélectriques [CISPR] standards. This standard gives the conducted emission range for different electronic devices.

Electromagnetism, Blood Flow and Coagulation

There is a lot of uncertainty in the theory of hemodynamics. The amount of work need to displace the blood in the systemic circulation, exceeds the work done by the left ventricle. With this, blood recovers increased flow resistance between the heartbeats with the Womersley number alterations in the rhythm of the accompanying electrocardiogram (ECG). Viscoelastic transformation is heavily expressed in coagulation. There must be a relationship between the ECG and blood transient flow resistance. The influence of the electromagnetic field on blood coagulation was studied. Venous blood was affected by the oscillated electromagnetic field (500 - 5000 Hz), with the square wave input signal in 25 healthy individuals (15 males, 10 females in the age 18 - 57 years). Electromagnetic irradiation (EMI) time of the sample 3 - 10 min. Hypocoagulation in normal blood samples was revealed (decreased quantity of Platelets up to 10 - 23 × 109/L, Prothrombin index up to 9% - 10%, Fibrinogen concentration up to 0.20 - 0.21 g/L) and thrombolysis after the blood stasis. Ac electric field from the myocardial depolarization initiates electroacoustic phenomena. An emerging repulsing electromagnetic force acts on the red blood cells (RBC) and in addition to the pulse pressure from the heart, promotes blood motion and viscoelastic changes. The alterations of the blood inertial and elasticity, in addition to hemodynamics, are facilitated by the magnetic features of the hemoglobin. The external electromagnetic signal can manage the blood coagulation process, including thrombolysis.

Pulsed electromagnetic fields preserve bone architecture and mechanical properties and stimulate porous implant osseointegration by promoting bone anabolism in type 1 diabetic rabbits.

Type 1 diabetes mellitus (T1DM) is associated with deteriorated bone architecture and impaired osseous healing potential; nonetheless, effective methods for resisting T1DM-associated osteopenia/osteoporosis and promoting bone defect/fracture healing are still lacking. PEMF, as a safe and noninvasive method, have proven to be effective for promoting osteogenesis, whereas the potential effects of PEMF on T1DM osteopathy remain poorly understood. We herein investigated the effects of PEMF stimulation on bone architecture, mechanical properties, bone turnover, and its potential molecular mechanisms in alloxan-treated diabetic rabbits. We also developed novel nontoxic Ti2448 pTi implants with closer elastic modulus with natural bone and investigated the impacts of PEMF on pTi osseointegration for T1DM bone-defect repair. The deteriorations of cancellous and cortical bone architecture and tissue-level mechanical strength were attenuated by 8-week PEMF stimulation. PEMF also promoted osseointegration and stimulated more adequate bone ingrowths into the pore spaces of pTi in T1DM long-bone defects. Moreover, T1DM-associated reduction of bone formation was significantly attenuated by PEMF, whereas PEMF exerted no impacts on bone resorption. We also found PEMF-induced activation of osteoblastogenesis-related Wnt/β-catenin signaling in T1DM skeletons, but PEMF did not alter osteoclastogenesis-associated RANKL/RANK signaling gene expression. We reveal that PEMF improved bone architecture, mechanical properties, and pTi osseointegration by promoting bone anabolism through a canonical Wnt/β-catenin signaling-associated mechanism. This study enriches our basic knowledge for understanding skeletal sensitivity in response to external electromagnetic signals, and also opens new treatment alternatives for T1DM-associated osteopenia/osteoporosis and osseous defects in an easy and highly efficient manner.

The Automatic Gain Control of the Digital Reconnaissance Receiver

On the basis of a brief introduction of how the automatic gain control (AGC) of the digital reconnaissance receiver works,this article proposed a digital AGC design method based on the digital processor parts, which provide a guarantee for the digital reconnaissance receiver to work in the complex external electromagnetic signal environment. The engineering implementation of AGC is introduced with specific projects. Both simulation and engineering practice verify the feasibility of this program.

Peculiarities of Operation of a Relativistic Backward-Wave Oscillator Driven by an External Electromagnetic Signal

We study operation of a relativistic backward-wave oscillator driven by an external electromagnetic signal. Such operation regimes as hard excitation of self-oscillations and amplification of the external signal are implemented experimentally. The conditions for possible synchronization of the relativistic backward-wave oscillator by an external signal is discussed. The possibility of accelerating the onset of oscillations by the action of an external signal is confirmed experimentally. The conditions of realization of the amplification regime and the main effects, which limit the amplification coefficient, are determined. The obtained results can be used to optimize the parameters of generators and amplifiers based on relativistic backward-wave oscillators.

Systems Information Therapy and the central role of the brain in allostasis

This work arose from the necessity to up date and clarify some basic concepts in contemporary medical practice such as those of health, disease, therapy and prevention. According to this perspective the work starts with a general epistemological review and goes on with an epistemological revision of biology and medicine. The concept of adaptation and the central role of the brain is then analysed and stated as the base to next consideration and deepening from a biophysical perspective. Physio-pathology of adaptation is assumed as a key concept in the definition and in the understanding of health and disease. A huge amount of endogenous and external stimuli has to be processed and response to them may lead to increase, stability or decrease of coherence in agreement with Frohlich's pioneering ideas. In this framework, the concept of stress, allostasis and allostatic load are outlined. Allostasis is defined as the capability of keeping stability through dynamic changes. A particular attention is paid to the emerging paradigms in biology and medicine especially those of system biology and system medicine trying to integrate the concept of complexity and hierarchical organization of the information flow in living organisms and in humans. In this framework biophysical signalling could play a significant role in modulating endogenous dynamics and in mediating external interactions. Additionally biophysical mechanisms could be involved in biological systems inner communication and could be responsible for the maintenance of systems inner coherence. The integration of the biophysical paradigm into contemporary medical practice is leading from one side to a better understanding of many pathways in physiopathology and from the other side to some new effective clinical applications. System Information Therapy is, for instance, is rising as a suitable and coherent tool in the application of thise concept being able to restore the self regulation and self regeneration capabilities both at the local and at the system level operating with endogenous and external electromagnetic signals in the range of the extremely low frequency electromagnetic signals. Some practical applications are described such as the clinical detection and treatment of fluctuating asymmetry by Vega Select 719. Fluctuating asymmetry, as well known, is related to the presence of an allostatic load and its disappearance after a biophysical treatment is a good clinical evidence of restoring of allostasis mediated by the brain at systemic level presumably through a biophysical repatterning in which we assume a key role should be played by membranes, cytoskeleton and especially by microtubules.

Prolonged Rhythm Monitoring for the Detection of Occult Paroxysmal Atrial Fibrillation in Ischemic Stroke of Unknown Cause

Atrial fibrillation (AF), commonly encountered in patients with ischemic stroke and transient ischemic attack (TIA), confers a 5-fold increased risk of ischemic stroke.1,2 AF-related strokes are associated with an ≈50% increased risk of disability and 60% increased risk of death at 3 months compared with strokes of other etiologies.3 Paroxysmal AF (PAF), a self-terminating recurrent form of cardiac arrhythmia that comprises between 25% and 62% of AF cases, may present as a brief single episode of arrhythmia or as clusters of abnormal rhythm of variable duration, sometimes evolving into a more persistent or permanent form.4 The self-terminating nature of PAF may lead to its underdiagnosis and consequent use of less effective treatment strategies (aspirin instead of oral anticoagulation) in poststroke patients. To address the underdiagnosis of PAF in patients with ischemic stroke and TIAs, several treatment guidelines have singled out the identification of PAF as an important goal after a stroke/TIA.5–8 The diagnosis of PAF, however, poses a challenge. Several features of AF (such as its brief duration, episodic frequency, and asymptomatic presentations) make its detection difficult and elusive to bedside screening measures, such as pulse monitoring and routine ECGs. To date, several studies have explored the use of prolonged noninvasive and invasive cardiac monitoring devices to identify AF but with variable success. After detection of AF, a cardioembolic mechanism is often inferred and anticoagulation occasionally prescribed for secondary stroke prevention. The routine use of cardiac monitoring to identify patients with PAF who will benefit from anticoagulation has been reported to be cost-effective.9 In this review, we provide an overview of the different methods of cardiac monitoring, summarize studies that investigated the incidence of PAF after stroke, and highlight gaps in our understanding of the pathogenic and prognostic significance of AF …

Electromagnetic brain mapping

There has been tremendous advances in our ability to produce images of human brain function. Applications of functional brain imaging extend from improving our understanding of the basic mechanisms of cognitive processes to better characterization of pathologies that impair normal function. Magnetoencephalography (MEG) and electroencephalography (EEG) (MEG/EEG) localize neural electrical activity using noninvasive measurements of external electromagnetic signals. Among the available functional imaging techniques, MEG and EEG uniquely have temporal resolutions below 100 ms. This temporal precision allows us to explore the timing of basic neural processes at the level of cell assemblies. MEG/EEG source localization draws on a wide range of signal processing techniques including digital filtering, three-dimensional image analysis, array signal processing, image modeling and reconstruction, and, blind source separation and phase synchrony estimation. We describe the underlying models currently used in MEG/EEG source estimation and describe the various signal processing steps required to compute these sources. In particular we describe methods for computing the forward fields for known source distributions and parametric and imaging-based approaches to the inverse problem.

Mode selection by application of an external signal in an overmoded gyrotron oscillator.

Mode control is achieved for the first time in a highly overmoded, pulsed rf oscillator by injection of an external electromagnetic signal (priming). The drive signal power, frequency, and time of application determine the degree of mode control. The regime of parameter space over which a primed gyrotron operates in a single stable mode is increased by \ensuremath{\sim}40%. A coupled mode theory is used to model the drive power dependency of the priming effect. Priming may allow gyrotrons to operate at increased efficiency as well as stabilize other overmoded coherent radiation sources.

The automatic rate adjustment pacemaker. The possibilities of rate hysteresis.

Since the first use of pacemakers there have been attempts to regulate the fixed, or basic rate of implanted pulse generators. Earlier models employed the use of magnets or percutaneous needles to change the pacemaker rate after implantation. A recent development is the programmable pacemaker, which utilizes external electromagnetic signals to alter the basic rate. A series of engineering advances have resulted in automatic pacemaker rate changes, as first embodied in the hysteresis pacemaker. Notable modifications of the basic hysteresis concept include gradual pacemaker rate changes, and variable hysteresis or rate changes dependent on electrophysiologic events. Many of these technical advances are unknown to physicians, but are disclosed in patents. In general, negative hysteresis favors emergence of underlying non-pacer rhythms, whereas positive hysteresis suppresses underlying rhythms of any type. The automatic rate adjustment pacemaker represents an attempt to derive the advantages of negative hysteresis while eliminating the disadvantages of abrupt rate changes. The unit automatically searches for a sinus rhythm slower than the basic pacing rate, by periodically gradually slowing its rate to a lower level.