Search

Track tests of ballistic aircraft in flight conditions are used to confirm their viability. A problem with track tests is vibration of the shoes in nonsteady slip along the rails. The monorail track at the Safronov State Government Testing Center for Aviation Systems has gaps between the track beams to allow for their expansion and contraction at different times of the year. In the acceleration of a test vehicle using the thrust of solid fuel rocket engines, parametric vibration appears. Its source is the dynamic interaction between the contact surface of the shoes and the upper surface of the monorail at the junction between sections. The dynamic vibrational stability of the moving test vehicle is studied in high-speed monorail tests. [ABSTRACT FROM AUTHOR]

We have successfully measured the sleep electroencephalogram (EEG) of 12 family cats during an afternoon nap using a completely noninvasive methodology originally developed and validated for family dogs. Extracting both macrostructural and spectral sleep variables from the acquired data, we: (1) provided a descriptive analysis of sleep structure in cats and the power spectral density (PSD) distribution considering 3 sleep stages—drowsiness, non-rapid eye movement (NREM), and rapid eye movement (REM) sleep; and (2) compared the results to those obtained in family dogs measured under the same conditions and using the same methodology. Importantly, our description of sleep structure and PSD distribution in cats proved to be comparable to those of earlier invasive studies, highlighting that appropriate noninvasive methodologies may provide a viable alternative to those that are invasive in some cases. While no macrostructural differences were found between the sleep of cats and dogs, and the characteristic PSDs were mostly similar across sleep stages within the 2 species, the high-frequency resolution comparison of PSD distributions revealed differences between the 2 species in all sleep stages (concerning the delta, theta, alpha, sigma, and beta bands in drowsiness and NREM sleep; and the delta, alpha, and sigma bands in REM sleep). Potential factors underlying these differences are discussed, including differences in circadian rhythms, sleep homeostatic regulation, experienced stress, or even differential attitudes toward owners—highlighting important links between sleep characteristics and often more complex neural and behavioral features. [ABSTRACT FROM AUTHOR]

Background: Migraine is a common debilitating disorder characterized by attacks of mostly unilateral, moderate to severe, throbbingheadaches. The diagnosis of migraine is made according to the third edition of the International Classification of Headache Disorders developed by the International Headache Society. There are several types of migraine, the most common of which are migraine without aura and migraine with aura. Objectives: This study aims to find the correlations between quantitative EEG changes and cognition in migraine patients. Patients and Methods: The study included 20 migraine patients,10 during pain attack (ictal phase) and 10 during pain-free period (inter-ictal), in addition to18 healthy controls.Montreal cognitive assessment and 20 minutes scalp EEG were done. After that, four seconds epochs were taken from the EEG record to find the powerspectral density (PSD) for each of the waves in the range of[detlaδ(0.5-4)Hz, theta θ(4-8)Hz, alpha α (8-12)Hz,and beta β (12-30)Hz]. The study was conducted in Al-Shaheed Ghazi Al-Hariri Hospital in Baghdad from October 1, 2022, to May 1, 2023. Results: Quantitative EEG analysis revealed that there is a significant decrease in theta and beta waves in descending pattern from control to inter-ictal and then to ictal migraine patientswhile alpha wave increased in ascending pattern from control to inter-ictal to ictal migraine patients. In cognition, there was a significant difference between controls and migraine patients in recall memory, language, and abstraction domains. Conclusions: Quantitative EEG findings suggest that alpha waves correlate negatively with cognition, while both theta and beta waves correlate positively with cognitive level. Received: June,, 2022 Accepted: Oct. 2023 Published: Jan.2024

Healing of various ailments using herbal medicines is gaining much interest. Plants classified as grasses, specifically Cynodon dactylon, are an appreciated group of monocots used in many herbal remedies. In this work, C. dactylon, is grown naturally and also under market available LED Luminaires with different lighting conditions. Until 2010, most of the plants are grown under conventional lamps that are not spectrally tunable. Cynodon dactylon, the grass is grown under two different light spectrum, two light levels and three photoperiods (9hours, 12 hours, 15 hours) to extend our experiential knowledge. The biomass accumulation was the highest when grown under a lower RB ratio-12-hour- $163\mu $ mol/s, and phenolic content was the highest at 92.8 mg/g wt Gallic Acid Equivalents under combined light source at 15-hour photoperiod. A spectrally tunable LED light source with an optimal quantity of LEDs saves cost, space and energy. Considering the light parameters from the light sources used for growing C. dactylon, Levenberg–Marquardt (LM) algorithm is implemented to select an optimal LED quantity that composes the light source. The algorithm simulates the given target spectrum with minimum fitness error. The method applied to model LEDs, its validation against the practical LED spectrum, spectrum matching and computation of Luminous flux, Photosynthetic Photon Flux and efficacy are also presented. Many spectrums are simulated to validate the performance of the algorithm. A solution of optimal LEDs for three Photosynthetic Photon Flux (PPF) levels with LEDs is derived, and it is observed that the number of LEDs increased with PPF.

Introduction Power spectral analysis is the most common method of quantitative electroencephalogram (qEEG) techniques and enables investigation of the microstructure of insomnia. Previous spectral analysis studies on insomnia have shown inconsistent results due to their heterogeneity and small sample sizes. Objectives We compared the difference of electroencephalogram (EEG) spectral power during sleep among participants without insomnia, insomniacs with no hypnotic use, hypnotic users with no insomnia complaints, and hypnotic users with insomnia complaints. Methods We used the Sleep Heart Health Study data, which is large sample size and has good quality control. The fast Fourier transformation was used to calculate the EEG power spectrum for total sleep duration within contiguous 30-second epochs of sleep. For 1,985 participants, EEG spectral power was compared among the groups while adjusting for potential confounding factors that could affect sleep EEG. Results The power spectra during total sleep differed significantly among the groups in all frequency bands (p corr < 0.001). We found that quantitative EEG spectral power in the beta and sigma bands of total sleep differed (p corr < 0.001) between participants without insomnia and hypnotic users with insomnia complaints after controlling for potential confounders. The higher beta and sigma power were found in the hypnotic users with insomnia complaints than in the non-insomnia participants. Conclusions This study suggests differences in the microstructures of polysomnography-derived sleep EEG between the insomnia groups. Disclosure No significant relationships.

Introduction. Today, many research endeavors are devoted to the miniaturization of microwave sources. One of the promising approaches is the use of magnetic nanostructures (spintronics elements), providing a wide range of frequency tuning and low power consumption. The main disadvantage of spintronics generators (spintransfer nanoscillators ‒ STNO) is a low output power of generated oscillations (tens of nanowatts and less). A possible solution is to sum up the power of many STNOs in a mutual synchronization mode.Aim. The investigation of noise properties of two connected STNOs with identical and non-identical parameters in a phase synchronization mode.Materials and methods. A model was developed of two STNOs interconnected by spin waves taking into account thermal noises. Spectral power densities of the amplitude and phase noise were obtained by the method of effective linearization.Results. Dependencies were obtained in a general form for attenuation coefficients of the amplitude and phase fluctuations of noise sources for each STNO. Three cases of synchronization were considered: completely identical STNOs, two identical STNOs but with different oscillation frequencies, and two non-identical STNOs, differing in an allowance of self-excitation by frequencies and amplitudes of the oscillations. It was possible to obtain a gain in the amplitude and phase noise for two identical STNOs. In this case, an increase in the allowance of self-excitation led to a decrease in the level of phase and amplitude noise.Conclusion. This analysis of the attenuation coefficients for non-identical STNOs demonstrates the possibility of improving the noise properties of each of the generators. In this case, the best noise value is obtained for an STNO with greater stability in a stand-alone mode.

A method has been developed for identifying the occurrence of incipient defects in the new ship machinery units that have not previously passed vibrodiagnostic testing, in the absence of statistical data on changes in the vibroacoustic parameters and diagnostic features under the action of characteristic malfunctions. A method for identifying faulty units with incipient defects under the action of unknown malfunctions has been implemented. An algorithm has been developed for constructing the boundaries of reference domains by integrating conditional multidimensional probability densities of feature spaces, which characterize the distribution of incipient defects for the operational state of the machinery. A rule is proposed for identifying the occurrence of incipient defects in individual machinery units in the case of multidimensional features passing beyond the boundaries of the reference domains. A rule is proposed for identifying the occurrence of incipient defects in the machinery units constructed based on a nonparametric goodness-of-fit criterion for assessing the coincidence of conditional distribution functions of multidimensional features characterizing these defects. Experimental verification of the developed method was carried out during in situ vibroacoustic tests of ship machinery. [ABSTRACT FROM AUTHOR]

Experimental model has been developed to study optoacoustic signal from model blood cells presented by polystyrene microspheres with nanoparticles. It was found out that nanoparticles due to their strong absorption of light significantly affect the coefficient of cellular optical absorption, while the thermophysical parameters, namely the coefficient of thermal expansion, compressibility and isobaric specific heat of cells remain unchanged, since nanoparticles occupy a small intracellular volume compared to the cell volume. Optoacoustic signals were obtained using model solutions at various concentrations of cells and nanoparticles using 1064 nm laser. The results of experimental measurements using LIMO 100–532/1064-U system based on Nd:YAG showed that the amplitude of the optoacoustic signal increased without increasing the temperature in the laser area.

Malaria causes a serious health problem in the tropical and subtropical regions of the globe. In many cases, the consequences of this disease are fatal. Therefore, a simple, fast, accurate and affordable diagnostic system for the early detection of this disease is necessary for the timely administration of antimalarial drugs.The malarial parasite, during its intra-erythrocyte development, processes a significant amount of hemoglobin, which in this case turns into a hem form called hemozoin. Hemozoin and hemoglobin have different molar extinction coefficients at certain optical wavelengths, hence, light absorption and an optoacoustic signal (OAS) from the infected cell will be different from that of a healthy cell. The paper describes the developed theoretical model intended for studying the influence of intra-erythrocyte malarial parasite development on optoacoustic signals. The OAS were calculated based on the models of healthy and infected blood modeled on the basis of a 3D model.The simulated OAS were analyzed in the temporal and frequency domains to obtain signs of infection at various stages. The calculated OAS spectra have different amplitude levels, which indicates that the optoacoustic method can be useful for differentiating various intraerythrocyte stages of the malarial parasite. The carried out modeling and the results obtained allow us to continue working on the creation of an optoacoustic flow cytometer.

Electrochemical noise of a commercial Li-ion battery was measured during the charging process. Statistical analysis was applied to show that measured noise possesses normal distribution without any peaks or transients. Skewness and kurtosis values were calculated to quantitatively describe distribution diagrams. Power spectral density frequency dependencies were calculated as well. They demonstrated the linear frequency dependence with the slope value close to –1.2 during the whole charge process and even during some overcharge. Electrochemical noise behavior under different charge currents was investigated for the first time. It was shown that the power spectral density level is proportional to the square of the charge current. [ABSTRACT FROM AUTHOR]

The electrochemical noise of a solid polymer air–hydrogen fuel cell was measured at different loads. Some of the common approaches to data treatment of electrochemical noise were tested. The dependences of the standard deviation and second and third central moments on the constant load current were calculated. The distribution diagrams were constructed. The spectral power density was calculated by Fourier transform using the wavelet transform and also through the standard deviations in the given frequency band. The data calculated by different methods were in good agreement. [ABSTRACT FROM AUTHOR]

The electrochemical noise of rechargeable lithium iron(II) phosphate (LiFePO4) battery was measured for the first time during discharge using a constant value resistor. A continuous data registration technique was applied to collect the noise measurement data. The standard deviation values were calculated for different state of charge values. Power spectral density frequency dependencies were obtained as well. The results showed that the standard deviation and spectrum slope absolute values increased at the end of the discharge process and may be used as indicators of over-discharge. Electrochemical impedance spectra were collected for the various discharge values and their properties were shown to correlate with the noise evolution during the discharge process. [ABSTRACT FROM AUTHOR]

The electrochemical noise of a primary lithium battery was measured at an open circuit by two experimental approaches: with a filtering capacitor and with the same battery to eliminate open circuit voltage of the system under test. Both methodologies give the same results if they are applied correctly but they can sometimes cause experimental problems. Two experiments were carried out with battery discharge at resistive load. It was shown that it is very difficult to provide the conditions for properly operation of the two battery method to avoid saturation of measurement device when the amplifier uses high gain values. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Hyperemesis gravidarum (HG) is a disease characterized by excessive vomiting and nausea during pregnancy. It differs from normal pregnancy where simple nausea and vomiting are seen frequently with unknown cause. The place and role of the brain in HG is unknown. METHODS: Thirty-three healthy pregnant women and 30 patients diagnosed with HG admitted to Selçuk University Faculty of Medicine, Obstetrics and Gynecology Department were included and electroencephalograph (EEG) signals of all patients obtained at Neurology Department were examined. These signals were evaluated with high math and examined with developed engineering methods. The sampling frequency of the EEG was 200 Hz. Data were obtained in the frequency-power axis using 0.1 Hz frequency resolution, Hamming windowing, and 0.5 overlap ratio with signals on the time axis on all channels. All sub-bands have formed with unearthed power spectral density as delta, theta, alpha, and beta and after being created was calculated spectral densities. RESULTS: As a result, while showing significant changes as delta band for Fp1F3, theta band for C3P3, F3C3, Fp1F3, P3O1, T5O1, for other channels and subbands has not seen any significant changes with regard to average power spectral density. DISCUSSION AND CONCLUSION: HG and normal pregnancies, when examined in terms of power spectral density, abnormalities were observed in the EEG signals in the left hemisphere frontal area of the delta band, fronto-centro-parietal, and parietal-occipital areas of the theta band. In light of the literature, neither cerebral abnormalities in HG could be displayed nor the place of abnormality could be shown. However, this study is the first to clearly show abnormalities of theta-delta band activity and differences of locations in the left cerebral hemisphere.

Copyright of Science-Based Technologies is the property of National Aviation University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Electrochemical noise of a Li/MnO2 primary lithium battery was measured and analyzed during discharge process for the first time. The amplitude of the noise is shown to increase during battery discharge. The power spectral density frequency dependences of the noise are calculated for various stages of the battery discharge. The amplitudes of power spectral densities of the current noise nearly linear depend on the discharge voltage for frequencies below 1 Hz. The slope of the spectral power density frequency dependence of voltage noise changes from − 1 to − 2 during the battery discharge. It was found that the magnitude and slope of the power spectral density frequency dependence of the noise can be considered as a discharge criterion for a primary lithium battery. [ABSTRACT FROM AUTHOR]

Recent empirical work suggests that the dynamics of brain function, as measured by brain signal variability, differs between younger and older adults. We extended this work by examining how the relationship between brain signal variability and age is altered in the context of expertise. We recorded electroencephalography from Scrabble experts and controls during a visual word recognition task. To measure variability, we used multiscale entropy, which emphasizes the way brain signals behave over a range of timescales and can differentiate the variability of a complex system (the brain) from a purely random system. We replicated previously identified shifts from long-range interactions among neural populations to more local processing in late adulthood. In addition, we demonstrated an age-related increase in midrange neural interactions for experts, suggesting greater maintenance of network integration into late adulthood. Our results indicate that expertise-related differences in the context of age and brain dynamics occur across different timescales and that these differences are linked to task performance. [ABSTRACT FROM AUTHOR]

Abstract—: A family of seismometers has been developed with capacitive transducers that convert the relative displacement between the inertial mass and the base of the instrument into an electric signal. These high-sensitivity seismometers have a unified electronic circuit; they can be rather easily manufactured, installed, and calibrated, which makes mass production of these instruments look promising. To assess the possibility of using these seismometers as substitutes for imported counterparts, a comparative analysis was carried out to study the performance of a portable short-period SM-3E broadband digital seismometer and imported seismometers of the same type. Seismic recordings of these instruments were statistically analyzed in the time and frequency domains. [ABSTRACT FROM AUTHOR]

The electrochemical noise of a polymer membrane hydrogen-air fuel cell operating at different load currents was measured in serial experiments. Spectral power densities of the noise are shown to be divided into three regions. At frequencies greater than 3-10 Hz, the spectrum dependence has a constant slope of − 2 in the bilogarithmic coordinates. At frequencies 0.3-5 Hz, there is a horizontal plateau in which length is determined by the value of a load. At frequencies less than 0.3 Hz, the dependence of spectral power density has a slope of − 2. Medium-frequency plateau and high-frequency slope of spectral power densities of the noise were approximated by model RC circuits. The values of Faradic resistance and double-layer capacitance connected in parallel were obtained from the electrochemical impedance data. At load voltages higher 0.5 V, the height of the plateau was shown to be proportional to the 2.68 power of the load current value. [ABSTRACT FROM AUTHOR]

The spatial resolutions of numerical atmospheric and oceanic circulation models have steadily increased over the past decades. Horizontal grid spacing down to the order of 1 km is now often used to resolve cloud systems in the atmosphere and sub-mesoscale circulation systems in the ocean. These fine resolution models encompass a wide range of temporal and spatial scales, across which dynamical and statistical properties vary. In particular, dynamic flow systems at small scales can be spatially localized and temporarily intermittent. Difficulties of current data assimilation algorithms for such fine resolution models are numerically and theoretically examined. An analysis shows that the background error correlation length scale is larger than 75 km for streamfunctions and is larger than 25 km for water vapor mixing ratios, even for a 2-km resolution model. A theoretical analysis suggests that such correlation length scales prevent the currently used data assimilation schemes from constraining spatial scales smaller than 150 km for streamfunctions and 50 km for water vapor mixing ratios. These results highlight the need to fundamentally modify currently used data assimilation algorithms for assimilating high-resolution observations into the aforementioned fine resolution models. Within the framework of four-dimensional variational data assimilation, a multiscale methodology based on scale decomposition is suggested and challenges are discussed. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A family of seismometers has been developed with capacitive transducers that convert the relative displacement between the inertial mass and the base of the device into an electric signal. The seismometers have high sensitivity and a unified electronic circuit, and they can be rather easily manufactured, installed, and calibrated. Mass production of these instruments looks promising. To assess the possibility of using these seismometers as substitutes for imported counterparts, a comparative analysis was carried out to study the performance of an SM-3E broadband sensor with a capacitive transducer and imported STS-2 and CMG-6T seismometers. Seismic recordings of these three instruments mounted on the same pedestal were statically analyzed in the time and frequency domains. [ABSTRACT FROM AUTHOR]

Objective: Hyperemesis gravidarum (HG) is a disease characterized by excessive vomiting and nausea during pregnancy. It differs from normal pregnancy where simple nausea and vomiting are seen frequently with unknown cause. The place and role of the brain in HG is unknown. Materials and Methods: Thirty-three healthy pregnant women and 30 patients diagnosed with HG admitted to Selçuk University Faculty of Medicine, Obstetrics and Gynecology Department were included and electroencephalograph (EEG) signals of all patients obtained at Neurology Department were examined. These signals were evaluated with high math and examined with developed engineering methods. The sampling frequency of the EEG was 200 Hz. Data were obtained in the frequency-power axis using 0.1 Hz frequency resolution, Hamming windowing, and 0.5 overlap ratio with signals on the time axis on all channels. All sub-bands have formed with unearthed power spectral density as delta, theta, alpha, and beta and after being created was calculated spectral densities. Results: As a result, while showing significant changes as delta band for Fp1F3, theta band for C3P3, F3C3, Fp1F3, P3O1, T5O1, for other channels and sub-bands has not seen any significant changes with regard to average power spectral density. Conclusion: HG and normal pregnancies, when examined in terms of power spectral density, abnormalities were observed in the EEG signals in the left hemisphere frontal area of the delta band, fronto-centro-parietal, and parietal-occipital areas of the theta band. In light of the literature, neither cerebral abnormalities in HG could be displayed nor the place of abnormality could be shown. However, this study is the first to clearly show abnormalities of theta-delta band activity and differences of locations in the left cerebral hemisphere. [ABSTRACT FROM AUTHOR]

Introduction: Our aim in this study was to investigate spectral power density (PSD) in first-episode mania and subsequent remission period and to evaluate their difference. Methods: Sixty-nine consecutive cases referring to our hospital within the previous 1 year, who were evaluated as bipolar disorder manic episode according to The Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) at the first episode and had the informed consent form signed by first degree relatives, were included in this study. Exclusion criteria included having previous depressive episode, using drugs which could influence electroencephalographic activity before electroencephalography (EEG), and having previous neurological disease, particularly epilepsy, head trauma, and/or loss of consciousness. EEG records were obtained using a digital device in 1 6 channels; 23 surface electrodes were placed according to the International 10-20 system. Spectral power density (dbµV/Hz) of EEG signal provided information on the power carried out by EEG waves in defined frequency range per unit frequency in the present study. Results: A peak power value detected on the right with FP2P4 and on the left with F7T3 electrodes were found to be higher in the manic episode than in the remission period (p=0.01 8 and 0.025). In the remission period, in cases with psychotic symptoms during the manic period, F4C4 peak power value was found to be lower than that in cases with no psychotic findings during the manic period (p=0.027). There was no relation was found between YMRS scores and peak power scores. Conclusion: Electrophysiological corollary of mood episode is present from the onset of the disease, and it differs between the manic and remission periods of bipolar disorder. In the remission period, peak power values of PSD distinguish cases with psychotic findings from cases without psychotic findings when they were manic. [ABSTRACT FROM AUTHOR]

Cosic discovered that spectral analyses of a protein sequence after each constituent amino acid had been transformed into an appropriate pseudopotential predicted a resonant energy between interacting molecules. Several experimental studies have verified the predicted peak wavelength of photons within the visible or near-visible light band for specific molecules. Here, this concept has been applied to a classic signaling pathway, JAK–STAT, traditionally composed of nine sequential protein interactions. The weighted linear average of the spectral power density (SPD) profiles of each of the eight “precursor” proteins displayed remarkable congruence with the SPD profile of the terminal molecule (CASP-9) in the pathway. These results suggest that classic and complex signaling pathways in cells can also be expressed as combinations of resonance energies. [ABSTRACT FROM AUTHOR]