Frequency-modulated Field Research Articles

Спектрально-угловые характеристики излучения заряженной частицы в поле частотно-модулированной электромагнитной волны

Based on the solution of the equation of motion of a charge in a frequency-modulated electromagnetic field, a classical theory of radiation of a relativistic charged particle linearly accelerated by a high-intensity chirped laser pulse is constructed. This solution was used to study the spectral-angular characteristics of the emission of a charged particle. According to the calculated formulas for the phase and phase-angular distributions of the intensity and power of the radiation of a particle in a modulated field, graphs of the dependence on the value of the modulation coefficient are plotted. Also obtained is the Fourier transform of the electric field strength of the radiation and the spectral density of the radiation of the particle in the case of linear polarization of the wave.

Mobile Phone Radiation Deflects Brain Energy Homeostasis and Prompts Human Food Ingestion.

Obesity and mobile phone usage have simultaneously spread worldwide. Radio frequency-modulated electromagnetic fields (RF-EMFs) emitted by mobile phones are largely absorbed by the head of the user, influence cerebral glucose metabolism, and modulate neuronal excitability. Body weight adjustment, in turn, is one of the main brain functions as food intake behavior and appetite perception underlie hypothalamic regulation. Against this background, we questioned if mobile phone radiation and food intake may be related. In a single-blind, sham-controlled, randomized crossover comparison, 15 normal-weight young men (23.47 ± 0.68 years) were exposed to 25 min of RF-EMFs emitted by two different mobile phone types vs. sham radiation under fasting conditions. Spontaneous food intake was assessed by an ad libitum standard buffet test and cerebral energy homeostasis was monitored by 31phosphorus-magnetic resonance spectroscopy measurements. Exposure to both mobile phones strikingly increased overall caloric intake by 22–27% compared with the sham condition. Differential analyses of macronutrient ingestion revealed that higher calorie consumption was mainly due to enhanced carbohydrate intake. Measurements of the cerebral energy content, i.e., adenosine triphosphate and phosphocreatine ratios to inorganic phosphate, displayed an increase upon mobile phone radiation. Our results identify RF-EMFs as a potential contributing factor to overeating, which underlies the obesity epidemic. Beyond that, the observed RF-EMFs-induced alterations of the brain energy homeostasis may put our data into a broader context because a balanced brain energy homeostasis is of fundamental importance for all brain functions. Potential disturbances by electromagnetic fields may therefore exert some generalized neurobiological effects, which are not yet foreseeable.

High-sensitivity operation of a single-beam atomic magnetometer for three-axis magnetic field measurement.

We demonstrate a single-beam atomic magnetometer (AM) capable of measuring a three-axis magnetic field with high-sensitivity, achieved by applying a small DC offset field and a high frequency modulation field. To satisfy the miniaturization demand of AMs, an elliptically polarized light detuned by 50 GHz from the resonance transition center is employed. The circularly polarized component is used to polarize the alkali-metal atoms, while the linearly polarized light is used to detect the dynamics of the polarized spin under a magnetic field. Based on theoretical analysis, parameters that significantly affect the performance are optimized, and a sensitivity of 20 fT/Hz1/2 in x-axis, 25 fT/Hz1/2 in y-axis, 30 fT/Hz1/2 in z-axis is achieved with a miniature 4 × 4 × 4 mm 87Rb vapor cell. Moreover, we also verify that the operation principle of AMs can be used to null background magnetic fields in-situ with isotropic compensation resolution of 6.7 pT, which provides an effectively precise method for zeroing ambient magnetic field. The high-sensitivity operating of an elliptically-polarized-laser-based magnetometer provides prospective futures for constructing a compact, low-cost AM, which is particularly applicable for non-invasive bio-magnetic imaging such as array-based magnetoencephalography (MEG) and magnetocardiography (MCG).

Evaluating the effectiveness of combined use of non-thermal atmospheric pressure plasma and frequently-modulated electric field signal in skin wound healing

Background Scientists around the world are interested in applying physical phenomena to various fields of science. The development of entire areas united by one concept (‘plasma medicine’, etc.) stands as a bright example. Present work focuses on only two concepts of interest, which are plasma jet and electric field, as far as results of their combined use in clinical practice and in surgery remain understudied. Objective Experimental evaluation of the effectiveness of physical methods of treatment in skin wound healing. Material and methods The study was carried out on 45 small laboratory animals (rats). They were divided into 5 groups of 9 individuals in each according to method chosen for experimental wound healing. To generate the plasma jet, a portable generator was used, which is the original development of specialists of the Peter the Great St. Petersburg Polytechnic University. Planimetric and histological measurements were analysed. The antibacterial effectiveness of methods under research was investigated using Staphylococcus aureus 209P, cultivated in vitro on 6- and 12-millimeter discs. Discussion The combined use of non-thermal atmospheric pressure plasma and frequency-modulated electric field signal exhibited the ability to accelerate eschar separation by 52.1% (p < 0.05) and stimulate restorative regeneration by 56% (p < 0.05). Combination of physical methods of treatment demonstrated pronounced antibacterial effect. A histological examination on biopsy sample on the 21st day of observation revealed formed (mature) granulations and large number of newly formed vessels. The cellular composition of epidermal basement membrane showed high level of differentiation. Conclusion The data obtained suggest that the use of the proposed methods in clinical practice will improve the treatment process of the patients with wounds of different etiology.

Measurement-Based Validation of Integrated Circuit Transient Electromagnetic Event Sensors

Determining the components or coupling paths responsible for soft failures during transient testing is challenging because the components are hidden within the product and because measuring internal voltages or currents during a transient test may not be practical. Adding cables to make voltage or current measurements may be difficult and may alter the test results. To overcome this problem, in this article, two compact sensors are designed to measure the peak over or undervoltage on a trace or pin during a transient electromagnetic event. One sensor uses an analog-to-digital converter to store the peak voltage digitally and the other sensor uses an external capacitor to store an analog measure of the peak voltage for a period of time. The sensors are designed to wirelessly transmit the peak level to a remote receiver using the frequency-modulated electric and magnetic fields so that no cables or other changes to the system are needed. The proof-of-concept of the sensors was implemented in an integrated circuit using 180 nm technology. The sensor performance is characterized by direct injection and by using them to detect the peak voltage on a universal serial bus (USB) cable during a cable-guided transient event. Both sensors successfully detected and transmitted the peak level of the event.

Electron-positron pair production in frequency modulated laser fields

The momentum spectrum and the number density of created electron-positron pairs in a frequency modulated laser field are investigated using quantum kinetic equation. It is found that the momentum spectrum presents obvious interference pattern. This is an imprint of the frequency modulated field on the momentum spectrum, because the momentum peaks correspond to the pair production process by absorbing different frequency component photons. Moreover, the interference effect can also be understood qualitatively by analyzing turning point structures. The study of the pair number density shows that the number density is very sensitive to modulation parameters and can be enhanced by over two orders of magnitude for certain modulation parameters, which may provide a new way to increase the number of created electron-positron pairs in future experiments.

OPPORTUNITIES FOR THE APPLICATION OF A FREQUENCY MODULATED ELECTRIC FIELD SIGNAL FOR TREATING BURNS AND THE RAS

The paper presents the results of an experimental study on the effect of a variable frequency-modulated electric field on the course of a wound process in a burn wound. The evaluation of the effectiveness of the antimicrobial action of wound healing agents against the background of an alternating frequency-modulated electric field has been carried out. The bacteriostatic effect of some wound healing agents used in combination with electrical physical and antiseptic action has been proven.

Visualization of frequency-modulated electric field based on photonic frequency tracking in asynchronous electro-optic measurement system

We propose a new asynchronous measurement system to visualize the amplitude and phase distribution of a frequency-modulated electromagnetic wave. The system consists of three parts: a nonpolarimetric electro-optic frequency down-conversion part, a phase-noise-canceling part, and a frequency-tracking part. The photonic local oscillator signal generated by electro-optic phase modulation is controlled to track the frequency of the radio frequency (RF) signal to significantly enhance the measurable RF bandwidth. We demonstrate amplitude and phase measurement of a quasi-millimeter-wave frequency-modulated continuous-wave signal (24 GHz ± 80 MHz with a 2.5 ms period) as a proof-of-concept experiment.

Laser cooling of 171Yb+ ions in a frequency-modulated field

We have investigated the laser cooling of ytterbium ions in a radio-frequency trap by a frequency-modulated resonant laser field. It has been shown that the lowest laser cooling temperatures, close to the Doppler limit, can be reached at field modulation parameters μ ⩾ 0.1. At lower μ values, the region of field parameters optimal for cooling shifts to higher intensities and the minimum possible laser cooling temperature increases.

Pseudorandom dynamics of frequency combs in free-running quantum cascade lasers

Recent research has shown that free-running quantum cascade lasers are capable of producing frequency combs in midinfrared and THz regions of the spectrum. Unlike familiar frequency combs originating from mode-locked lasers, these do not require any additional optical elements inside the cavity and have temporal characteristics that are dramatically different from the periodic pulse train of conventional combs. Frequency combs from quantum cascade lasers are characterized by the absence of sharp pulses and strong frequency modulation, periodic with the cavity round trip time but lacking any periodicity within that period. To explicate for this seemingly perplexing behavior, we develop a model of the gain medium using optical Bloch equations that account for hole burning in spectral, spatial, and temporal domains. With this model, we confirm that the most efficient mode of operation of a free-running quantum cascade laser is indeed a pseudorandom frequency-modulated field with nearly constant intensity. We show that the optimum modulation period is commensurate with the gain recovery time of the laser medium and the optimum modulation amplitude is comparable to the gain bandwidth, behavior that has been observed in the experiments.

Transformation of the frequency-modulated continuous-wave field into a train of short pulses by resonant filters

The resonant filtering method transforming frequency modulated radiation field into a train of short pulses is proposed to apply in optical domain. Effective frequency modulation can be achieved by electro-optic modulator or by resonant frequency modulation of the filter with a narrow absorption line. Due to frequency modulation narrow-spectrum CW radiation field is seen by the resonant filter as a comb of equidistant spectral components separated by the modulation frequency. Tuning narrow-bandwidth filter in resonance with $n$-th spectral component of the comb transforms the radiation field into bunches of pulses with $n$ pulses in each bunch. The transformation is explained by the interference of the coherently scattered resonant component of the field with the whole comb. Constructive interference results in formation of pulses, while destructive interference is seen as dark windows between pulses. It is found that the optimal thickness of the resonant filter is several orders of magnitude smaller than the necessary thickness of the dispersive filters used before in optical domain to produce short pulses from the frequency modulated field.

Control of the photoelectron dynamics for the effective conversion of short-pulse, frequency-modulated optical radiation into X-ray radiation

We report a theoretical investigation of high-order harmonic generation (HHG) in the ionisation of atoms by nonlinear frequency-modulated laser pulses of short duration. It is shown that the reduction in the instantaneous value of the laser pulse frequency can lead to a significant increase in the width of the plateau in the HHG spectrum. We have found optimal parameters of frequency modulation at which photons with energies of are efficiently generated at a relatively low laser-pulse intensity. High HHG efficiency at optimal parameters is explained by the peculiarities of atomic ionisation dynamics and acceleration of photoelectrons by a frequency-modulated laser field.

Differential Tumor Prevalence of Geriatric Rats that had been Exposed Prenatally to One of Two Complex, Physiologically- Patterned Magnetic Fields

A total of 165 male and female rats that had been exposed during their entire prenatal development to either one of two complex, patterned magnetic fields or to reference (colony) conditions were monitored for emergence of “spontaneous” body tumours until old age (two years after birth). The two patterns were a frequency modulated (FM) field that has been shown to slow malignant cell but not normal cell growth in culture and a complex-sequenced (CSF) field. It was composed of 8 components with 6 of these components containing 8 subcomponents presented for 200 ms for 10 s every 40 s. Significantly greater proportion (33%) of the old rats that had been exposed prenatally to the complex-sequenced field displayed tumors (primarily mammary adenocarcinoma and fibrocarcinoma varieties). Most of these tumors occurred in rats that had been exposed to 30 to ~600 nT strengths but not less than 30 nT or greater than ~600 nT intensities. In comparison 4% of the rats exposed to the single, repeated frequency-modulated field exhibited tumors. The prevalence for normal background colony room conditions was 2%. These data suggest that exposure during prenatal development to weak intensity magnetic fields whose temporal patterns were designed to be convergent with the timing of base sequencing could increase the probability of the development of cancer during the later stages of life. However the frequency-modulated magnetic field pattern that suppress the growth of human breast cells in culture and elicits strong analgesia in rodents produced no significant increase in emergence of tumors in later life compared to non-treated rats.https://maltcasino.fun/https://pinbahis.fun/https://onwin.direct/https://130betebet.com/https://detectivestripes.com/

Fiber-optic magnetic-field imaging.

We demonstrate a scanning fiber-optic probe for magnetic-field imaging where nitrogen-vacancy (NV) centers are coupled to an optical fiber integrated with a two-wire microwave transmission line. The electron spin of NV centers in a diamond microcrystal attached to the tip of the fiber probe is manipulated by a frequency-modulated microwave field and is initialized by laser radiation transmitted through the optical tract of the fiber probe. The two-dimensional profile of the magnetic field is imaged with a high speed and high sensitivity using the photoluminescence spin-readout return from NV centers, captured and delivered by the same optical fiber.

Velocity selective trapping of atoms in a frequency-modulated laser field

The wavefunction of a moderately cold atom in a stationary near-resonant standing light wave delocalizes very fast due to wave packet splitting. However, we show that frequency modulation of the field may suppress packet splitting for some atoms having specific velocities in a narrow range. These atoms remain localized in a small space for a long time. We propose that in a real experiment with cold atomic gas this effect may decrease the velocity distribution of atoms (the field traps the atoms with such specific velocities while all other atoms leave the field).

Frequency-modulated light scattering in colloidal suspensions

Frequency-modulated light field fluctuations due to moving particles in colloidal suspensions are examined using heterodyne interferometry. The power spectrum is the combined result of a time-of-flight-related frequency distribution due to light scattering and frequency shifts due to the Doppler effect. An approximation model is developed based on diffusion theory and verified experimentally. The potential for application towards comprehensive diagnosis of both particle dynamics and optical properties of the examined media is discussed.

Анализ нестационарных свойств когерентного пленения населённостей в частотно-модулированных полях

Анализ нестационарных свойств когерентного пленения населённостей в частотно-модулированных полях

Frequency modulation spectroscopy of coherent dark resonances of multi-level atoms in a magnetic field

The resonances of coherent population trapping (CPT) excited by a frequency-modulated (FM) field at the Zeeman sublevels during the transition F g = 2 → F e = 1 of the 87Rb D 1-absorption line were studied theoretically. The influence of the nonlinear Zeeman effect on the structure of the observed resonances was considered. The spectra of CPT resonances were calculated for different values of magnetic field induction and compared with the experimental data.

Unconventional geometric phase gate and multiqubit entanglement for hot ions with a frequency-modulated field

We present an alternative scheme for implementing the unconventional geometric two-qubit phase gate and preparing multiqubit entanglement by using a frequency-modulated laser field to simultaneously illuminate all ions. Selecting the index of modulation yields selective mechanisms for coupling and decoupling between the internal and the external states of the ions. By the selective mechanisms, we obtain the unconventional geometric two-qubit phase gate, multiparticle Greenberger—Horne—Zeilinger states and highly entangled cluster states. Our scheme is insensitive to the thermal motion of the ions.

Frequency-modulation spectroscopy of coherent dark resonances in 87Rb atoms

The results of frequency-modulation (FM) spec- troscopy of coherent dark resonances from the Zeeman sub- levels of the transition F = 2 ↔ F = 1o fD1 line in absorp- tion of 87 Rb atoms are presented and discussed in detail. By contrast with the conventional spectroscopy of coherent dark resonances employing two laser beams, relative frequency of which can be varied, these data has been obtained with the help of a single frequency-modulated laser field. Varia- tion of the modulation frequency plays then a similar role as the variation of the relative frequency in conventional spec- troscopy. Experimental data are fit to the theoretical calcu- lations, which are based on the theory of FM spectroscopy of coherent dark resonances recently developed by us. Fea- sibility of using such experimental technique for accurate measurements of magnetic fields is also discussed.