Adjacent Frequency Research Articles

Expanded Generalized Needlet Internal Linear Combination (eGNILC) Framework for the 21 cm Foreground Removal

Abstract The Generalized Needlet Internal Linear Combination (GNILC) method is a nonparametric component separation algorithm to remove the foreground contamination of the 21 cm intensity mapping data. In this work, we perform the discrete cosine transform along the frequency axis in the expanded GNILC framework (denoted eGNILC), which helps reduce the power loss in low multipoles, and further demonstrates its performance. We also calculate the eGNILC bias to modify the criterion for determining the degrees of freedom (dof) of the foreground, and embed the robust principal component analysis in mixing matrix computation to obtain a blind component separation method. We find that the eGNILC bias is related to the averaged domain size and the dof of the foreground but not the underlying 21 cm signal. In the case of no beam effect, the eGNILC bias is negligible for simple power-law foregrounds outside the Galactic plane. We also examine the eGNILC performance in the SKA Phase-I in mid-frequency (SKA-MID) and Baryon Acoustic Oscillations from Integrated Neutral Gas Observations (BINGO) simulations. We show that if the adjacent frequency channels are not highly correlated, eGNILC can recover the underlying 21 cm signal with good accuracy. With the varying Airy-disk beam applied to both SKA-MID and BINGO, the power spectra of 21 cm can be effectively recovered at the multipoles ℓ ∈ [20, 250] and [20, 300], respectively. With no instrumental noise, the SKA-MID exhibits ≲20% power loss, and BINGO exhibits ~10% power loss. The varying Airy-disk beam only causes significant errors at large multipoles.

3D-printed OAM beam generator with an enhanced out-of-band gain filtering characteristic

In this paper, a 3D-printed orbital angular momentum (OAM) beam generator is proposed with integrated gain-filtering characteristics. The proposed design is composed of an integrated all-resonator 1-to-8 filtering power divider, eight-phase delay lines with twisted waveguides, and an eight-horn circular array. Unlike conventional fabrication methods, the proposed OAM generator is monolithically fabricated using selective laser melting (SLM) 3D-printing technology. Experimental results demonstrate that the proposed design achieves OAM beams with mode number l =+1 and a mode purity of around 80%. Additionally, it exhibits a gain-filtering response with out-of-band suppression levels exceeding 30 dB in the main beam directions. The air-filled all-metal structure allows the OAM beam generator to achieve a maximum total efficiency of over 80%. The proposed OAM generator with gain filtering response not only enhances channel capacity but also helps to avoid adjacent frequency interference, demonstrating great potential in millimeter-wave (mm-Wave) wireless systems.

Development and validation of a two-dimensional pseudorandom balance perturbation test.

Pseudorandom balance perturbations use unpredictable disturbances of the support surface to quantify reactive postural control. The ability to quantify postural responses to a continuous multidirectional perturbation in two orthogonal dimensions of sway (e.g., AP and ML) has yet to be investigated. We developed a balance perturbation paradigm that used two spectrally independent sum of sinusoids signals (SoS1, SoS2), one for each orthogonal dimension of tilt (roll and pitch), to deliver a two-dimensional (2D) balance perturbation. In a group of 10 healthy adults we measured postural sway during 2D perturbations, as well as for each of the two individual 1D perturbation components. We found that during 2D perturbations, spectral peaks in the sway response were larger at the perturbed frequencies when compared to (1) the adjacent non-perturbed frequencies and (2) the frequencies contained within the orthogonal, spectrally independent perturbation signal. We also found that for each of the two spectra (SoS1, SoS2), the magnitude and timing of the sway response relative to the platform disturbance was similar when measured during 1D and 2D conditions. These data support that our novel 2D SoS perturbation test was able to evoke ML and AP postural responses that were (1) specific to the roll and pitch perturbations, respectively, and (2) similar to the responses provoked by individual 1D perturbations.

A filtering polarization conversion electromagnetic surface for simultaneous RCS reduction and transmission

A novel bifunctional single-sheet electromagnetic surface is proposed in this paper. To alleviate the mutual coupling of the two functions, an equivalent series circuit for linear-to-linear polarization conversion and an equivalent parallel circuit for filtering property are cascaded. Thanks to the combination of different equivalent circuits and the displacement of the resonating parts of two functions, the proposed electromagnetic surface demonstrates filtering and polarization conversion properties in adjacent frequency bands. When the unit cell is periodically arranged to constitute a finite metasurface, more than 6 dB RCS reduction is obtained from 7.7 GHz to 22.8 GHz. The physical mechanism reveals that the low RCS property of the metasurface is in virtue of both scattering field cancellation and transmission. The simple structure, relatively small cell size and good performance of the metasurface suggest it may be a promising candidate as antenna radome. Moreover, the proposed integration method of different functions in one surface makes the design of multifunctional electromagnetic surface easier and faster.

(Digital Presentation) Internal Friction, Mechanical Spectroscopy of SiO2, Radiation Functionalized Nanocomposites of Multiwalled Carbon Nanotubes and Polyamide, Polyethylene, Polyvinylchloride

Introduction A method for determining the integral density of structural defects nD in SiO2+Si disk – wafer plates was developed, which is the basis of metal – dielectric – semiconductor (MDS) structures in the manufacture of large integrated circuits (LIC) for production technology to express the post-operational control of the perfection of the structure of multilayer epitaxial structures and the growth reliability of decent p-n junctions in the production of semiconductor devices [1-3]. Amplitude-dependent IF measurement (ADIF) can be used as a highly sensitive method to monitor the nanoplastic deformation eND of SiO2+Si wafer plates [4-6]. Experimental procedure The study of the influence of structural defects on the damping of vibrations of SiO2+Si wafer plates with diameter D ≈ 100 mm and thicknesses of hSiO2 ≈ 600 nm allows the estimation of the degree of perfection of the crystalline structure. Ultrasonic (US) pulse-phase method using USMV-LETI, modernized USMV-KNU and computerized “KERN-4” devices with frequencies f┴ ≈ 0.7 MHz and f║ ≈ 1 MHz and were used [7-10]. Results and discussion The temperature dependence of IF Q-1(T) in SiO2+Si wafer plates p-type, doped with B, KDB-7.5(100) with diameter D ≈ 100∙10-3 m, SiO2 layer thickness hSiO2 ≈ 100 nm, and Si layer thickness hSi ≈ 460∙103 nm are shown. IF Q-1 , mechanical spectroscopy of radiation functionalized nanocompositesof MCNT polyamide (NH(CH2)5CO)n, polyethylene (C2H4)n, and polyvinylchloride (C2H3Cl)n are presented. The influence of ultrasound (US) deformation εUS studied on IF Q-1 and dynamic elastic modulus E = r V║ 2 , dynamic shear modulus G = r V ^ 2 of MCNT nanocomposites. Conclusions The study of SiO2+Si wafer-plate vibrations at adjacent harmonic frequencies f0 and f2 made it possible to develop a technique for determining the structural defect density nD and the broken layer depth hBL .Internal friction Q-1 , dynamical shear modulus G, dynamical elastic modulus Е, Poisson coefficient μ are dependent from SiO2+Si wafer-plate anisotropy.The increase of the nanocomposite crystallinity degree at growth of multiwalled carbon nanotubes concentration filling with the nanotubes of matrix results in the decline of content of organized phase.As the result of mechanical study the presence of the strong effect between polyamide, polyvinylchloride, polyethylene and multiwalled carbon nanotubes was confirmed. The presence of the strong interaction for nanocomposite between polyamide-6 (NH(CH2)5CO)n and multiwalled carbon nanotubes was confirmed by mechanical studies.

Optimization and imputation of acoustic absorption sequence prediction for transversely isotropic porous materials: A MultiScaleCNN-Transformer-PSO model approach

To address the limitations of traditional methods in real-time prediction and adaptive optimization of sound absorption coefficients for transversely isotropic porous materials. This study introduces a method combining a Multi-Scale Convolutional Neural Network (MultiScaleCNN) and a Transformer model to improve real-time prediction and optimization of sound absorption coefficients in transversely isotropic porous materials. Using a validated transfer matrix method based on the Biot model and acoustic analysis via COMSOL 6.2, a database of sound absorption curves was created. MultiScaleCNN extracts multi-scale features, which the Transformer model uses for sequence-to-sequence modeling with a self-attention mechanism, effectively managing complex dependencies. The model achieves high accuracy in full-mask prediction, closely aligning with actual values. Additionally, Particle Swarm Optimization (PSO) optimizes sound absorption coefficients in the 1000–2000 Hz range, meeting the fitness function’s criteria. For partial-mask imputation, the model uses adjacent frequency data and features to enhance accuracy. Results show that the MultiScaleCNN-Transformer-PSO model offers a robust, data-driven approach for predicting and optimizing sound absorption coefficients, advancing the field.

Implementing Superresolution of Nonstationary Tides with Wavelets: An Introduction to CWT_Multi

Abstract Tides are often nonstationary due to nonastronomical influences. Investigating variable tidal properties implies a trade-off between separating adjacent frequencies (using long analysis windows) and resolving their time variations (short analysis windows). Previous continuous wavelet transform (CWT) tidal methods resolved tidal species. Here, we present CWT_Multi, a MATLAB code that 1) uses CWT linearity (via the “response coefficient method”) to implement superresolution, i.e., resolving tidal constituents beyond the Rayleigh criterion; 2) provides a Munk–Hasselmann constituent selection criterion appropriate for superresolution; and 3) introduces an objective, time-variable form of inference (“dynamic inference”) based on time-varying data properties. CWT_Multi resolves tidal species on time scales of days, and multiple constituents per species with fortnightly filters. It outputs astronomical phase lags and admittances, analyzes multiple records, and provides power spectra of the signal(s), residual(s), and reconstruction(s); confidence limits; and signal-to-noise ratios. Artificial data and water levels from the Lower Columbia River Estuary (LCRE) and San Francisco Bay Delta (SFBD) are used to test CWT_Multi and compare it to harmonic analysis programs NS_Tide and UTide. CWT_Multi provides superior reconstruction, detiding, dynamic analysis utility, and time resolution of constituents (but with broader confidence limits). Dynamic inference resolves closely spaced constituents (like K1, S1, and P1) on fortnightly time scales, quantifying impacts of diel power peaking (with a 24-h period, like S1) on water levels in the LCRE. CWT_Multi also helps quantify the impacts of high flows and a salt barrier closing on tidal properties in the SFBD. On the other hand, CWT_Multi does not excel at prediction, and results depend on analysis details, as for any method applied to nonstationary data. Significance Statement Ocean tides, especially in coastal and estuarine systems, are often nonstationary, in the sense that the mean and standard deviation of tidal properties vary over time, usually in response to some nontidal process. We introduce here a MATLAB code, CWT_Multi, that uses wavelet transforms to resolve both tidal species and constituents on time scales from a few days to months. Our code accommodates multiple scalar time series and has typical tidal analysis features like constituent selection and inference, plus two forms of uncertainty analyses. It is flexible, allowing the user to adapt analysis properties to diverse datasets. CWT_Multi is applicable to many problems involving time-variable tides, including sea level rise, compound flooding, sediment transport, and wetland habitat analyses. Application to vector data is a straightforward extension, but further development of our uncertainty analysis is merited. Because nonstationary tidal analysis is rapidly advancing, we also define the features of a “well-formed” analysis code.

A novel optimal resonance band selection method for wheelset-bearing fault diagnosis based on tunable-Q wavelet transform

The detection of faults in the wheelset-bearing system is crucial for guaranteeing the safety of train operations. The core is to extract the optimal resonance band (ORB) and repetitive transient impact signals from the collected axle box acceleration signals. Accordingly, a novel automatic fault detection method called the bidirectional iterative merging multi-Q tunable-Q wavelet transform (BIMMQTQWT) is proposed to address the issue that existing methods are vulnerable to background noise and irrelevant components. First, a series of band-pass filters with almost constant bandwidth are constructed by the improved multi-Q tunable-Q wavelet transform (IMQTQWT) derived from the fault characteristics. Second, the fault information contained in each sub-band coefficient is preliminarily estimated using the correlative envelope comprehensive indicator (CECI). Third, the ORBs are automatically selected using the maximum CECI based on a strategy called bidirectionally merging adjacent frequency bands (BIMFBs). Finally, Envelope demodulation based on the ORB is executed followed by identifying bearing faults. The effectiveness in detecting multiple wheelset-bearing faults of the proposed method is validated through simulation and bench experiment signals. And the superior performance of the proposed method is exhibited compared with the existing average infogram and resonance sparse decomposition.

Cross-cultural adaptation and psychometric validation of the Chichewa (Malawi) PedsQL™ 4.0 Generic Core Scales child self-report and PedsQL™ 4.0 GCS teen self-report

BackgroundThe PedsQL™ 4.0 Generic Core Scales (GSC) have been translated into over 60 languages, but use in the sub-Saharan African region is limited. This study aimed to cross-culturally adapt and validate the PedsQL™ 4.0 GCS child self-report and teen self-report versions into the Chichewa language for Malawi.MethodsThe English (USA) versions were adapted (translation, back translation and cognitive interviews to evaluate conceptual equivalence) into Chichewa. We recruited 289 children (8–17 years) in Blantyre, Malawi. Classical psychometrics at the item level (missing data, endorsement frequencies, item redundancy) and scale level (internal consistency, convergent, discriminant and known groups validity) was used to evaluate the new Chichewa versions.ResultsSix items were found to need cultural adaptation for Malawi. There were problems with missing data (< 5%) and adjacent endorsement frequency (< 10%) among younger children. Internal consistency reliability was acceptable (Cronbach α > 0.7). Convergent validity was generally strong (correlations > 0.4). Discriminant validity (p > 0.05) was evident with respect to gender and age, but not for school grade (p < 0.05). Effect sizes indicating known groups validity were in the expected direction but of variable magnitude.ConclusionWe have successfully adapted the PedsQL™ 4.0 GCS child self-report and teen self-report into Chichewa for use in Malawi. Many aspects of the psychometric evaluation were promising, though some elements were more mixed and we have not yet been able to evaluate test-retest reliability or responsiveness. We suggest that the PedsQL™4.0 GCS child and teen self-reports should be used with caution among children and adolescents in Malawi.

Wake flow behind a transversely rotating sphere confined in a pipe at low Reynolds numbers

Direct numerical simulations are performed to investigate the flow past a transversely rotating sphere confined in a pipe. Three sphere diameters of d=0.2D, 0.5D, and 0.8D (D is the pipe diameter) and sphere Reynolds numbers (based on the sphere cross-sectional mean velocity and d) of Res=250–500 are considered. The simulation results highlight the combined effects of the blockage ratio (BR=d/D) and the nondimensionalized rotation rate Ω in the range of 0.2–1.2 on the wake flow. For each BR, with increasing Res and Ω, the wake flow undergoes a transition of the flow pattern from steady symmetry and unsteady symmetry to unsteady asymmetry. For BR=0.2, the variation in flow behaviors with Ω is similar to those reported in the previous studies on a transversely rotating sphere subjected to a uniform flow. With increasing BR from 0.2 to 0.5, the unsteady asymmetric wake flow is characterized by distorted near-wake vortex rings and a series of staggered inward rolled-up vortex arcs on the double streamwise vortex threads, which results in a low-frequency modulation of the unsteady wake flow. These rolled-up vortex arcs are connected with downstream quasi-streamwise vortices and form hairpin-like vortices. Dynamic Mode Decomposition (DMD) analysis shows that the distorted near-wake vortex rings are associated with the antisymmetric DMD mode at the adjacent frequency around the symmetric primary DMD mode. With BR=0.8, there is a drastic increase in the sphere's force coefficients. A more complex wake flow behavior is found due to a strong interaction between the wake flow and the near-pipe-wall flow. At Ω=1.2, dominant asymmetric flow structures are characterized by impingement of the vortex filaments. The low-frequency modulation of these wake structures is also analyzed using the DMD analysis.

Time/frequency domain analysis of detonation wave propagation mechanism in a linear rotating detonation combustor

Controlling the rotating detonation combustor (RDC) is crucial for enhancing propulsion system safety, efficiency, and overall performance. Swift and precise identification of the operational mode of RDC is of great significance for refining the propulsion dynamics of detonation-based technologies. In this study, two-dimensional numerical simulations are performed to investigate time-domain characteristics and frequency-domain characteristics of various operational modes of the RDC, hydrogen–air mixtures are used as fuel, and fast Fourier transformation (FFT) is applied to the analysis of frequency-domain. The alteration of the RDC operational mode is achieved through adjustments to the chemical equivalent ratio (ER) of the fuel, spanning from 0.52 to 3.50. Our findings reveal four distinct operational modes within this equivalent ratio range: ignition failure (ER ≤ 0.52 and ER ≥ 3.50), collision failure (ER = 0.85, 1.60 and 1.65), single wave (0.53 ≤ ER ≤ 0.80 and 1.70 ≤ ER ≤ 3.40) and multiple wave mode (0.90 ≤ ER ≤ 1.50). For the ignition failure mode, the detonation waves in RDC decouple from the flame and fail after ignition. In the collision failure mode, the inability of detonation waves to propagate sustainably within the RDC is evident. Frequency-domain analysis underscores the significance of a characteristic low-frequency (0.3 kHz) in distinguishing this mode from others. For single wave mode, it represents the steady and continuous propagation of a detonation wave in the RDC. Frequency-domain analysis reveals characteristic frequencies approximately equal to integer multiples of the propagation frequency (fD), where fD ∼ 10fD serves as the primary characteristic frequencies. The multiple wave mode can be categorized into two subtypes: the forward and reverse single detonation waves appear alternately or the forward and reverse single detonation waves finally co-direction double detonation waves. In the former subtype, characteristic frequencies are integer multiples of the fD, but the amplitude distribution is different with single wave mode. In contrast, primary characteristic frequencies of the latter subtype are fD ∼ 4fD, accompanied by two adjacent characteristic frequencies near each integer multiples of fD. These findings promise advancements in the controllability of RDC and lay the foundations for the development of RDC control systems.

Modal Parameter Recursive Estimation of Concrete Arch Dams under Seismic Loading Using an Adaptive Recursive Subspace Method.

Modal parameter estimation is crucial in vibration-based damage detection and deserves increased attention and investigation. Concrete arch dams are prone to damage during severe seismic events, leading to alterations in their structural dynamic characteristics and modal parameters, which exhibit specific time-varying properties. This highlights the significance of investigating the evolution of their modal parameters and ensuring their accurate identification. To effectively accomplish the recursive estimation of modal parameters for arch dams, an adaptive recursive subspace (ARS) method with variable forgetting factors was proposed in this study. In the ARS method, the variable forgetting factors were adaptively updated by assessing the change rate of the spatial Euclidean distance of adjacent modal frequency identification values. A numerical simulation of a concrete arch dam under seismic loading was conducted by using ABAQUS software, in which a concrete damaged plasticity (CDP) model was used to simulate the dam body's constitutive relation, allowing for the assessment of damage development under seismic loading. Utilizing the dynamic responses obtained from the numerical simulation, the ARS method was implemented for the modal parameter recursive estimation of the arch dam. The identification results revealed a decreasing trend in the frequencies of the four initial modes of the arch dam: from an undamaged state characterized by frequencies of 0.910, 1.166, 1.871, and 2.161 Hz to values of 0.895, 1.134, 1.842, and 2.134 Hz, respectively. Concurrently, increases in the damping ratios of these modes were observed, transitioning from 4.44%, 4.28%, 5.42%, and 5.56% to 4.98%, 4.91%, 6.61%, and 6.85%%, respectively. The correlation of the identification results with damage progression validated the effectiveness of the ARS method. This study's outcomes have substantial theoretical and practical importance, facilitating the immediate comprehension of the dynamic characteristics and operational states of concrete arch dam structures.

A phase 1 clinical trial of DB-020 intratympanic injections administered prior to high-dose cisplatin chemotherapy to reduce ototoxicity.

6100 Background: Hearing loss (HL) as a result of cisplatin (CP) chemotherapy is common. DB-020 is a formulation of sodium thiosulfate for intratympanic (IT) injection being developed to reduce CP ototoxicity. This phase 1 study was designed to evaluate safety and tolerability of repeated IT injections of DB-020 and compare CP-induced hearing changes with DB-020 vs placebo. Methods: Patients scheduled for at least three cycles of CP and cumulative exposure of ≥280 mg/m2 were randomized to blinded, bilateral, IT injection with DB-020 (12% or 25%) in one ear and placebo in the other ear, once every 3 or 4 weeks, ≤3 hours before receiving CP. Patients naïve to CP with moderate or severe HL at baseline were excluded. Ototoxicity was defined by American Speech-Language-Hearing criteria: ≥20 dB threshold increase at any one test frequency, or ≥10 dB threshold increase in any two adjacent frequencies, or loss of response at three consecutive frequencies where responses were previously obtained. Severe ototoxicity was defined as ≥20 dB threshold increase in any two adjacent frequencies. Pre-specified analyses evaluated safety, ototoxicity (with McNemar’s test using the last observation carried forward), and average threshold shifts (from air conduction audiometry, analyzed with a mixed model with repeated measures). This is the final analysis of the data set following the interim analysis presented in 2023. Results: Twenty-two patients were randomized with a mean age of 55 years (86% male; 100% white). Pre-DB-020 treatment, mean cumulative CP dose was 255 mg/m2, and 95% had head and neck cancers; 5% had lung cancer. Twenty patients had both baseline and follow-up audiometry, and 18/20 had baseline audiograms within 5 dB of the median threshold for age-matched controls. Free CP systemic levels (overall mean cumulative CP dose was 254.7 mg/m2) were similar to reference values. Acute or temporary ear pain (18/22 patients, 82%), and tinnitus (11/22 patients, 50%) were common. Ear pain was more common in DB-020 treated ears, and tinnitus in placebo treated ears. No persistent tympanic perforations, no serious adverse events in the ear and labyrinth disorders category, and no deaths were reported. Ototoxicity was significantly more common and severe in placebo treated ears. Conclusions: In this initial clinical trial experience, there was no significant safety signal, and DB-020 IT injections showed a meaningful reduction in CP-induced ototoxicity. Clinical trial information: NCT04262336 . [Table: see text]

Broadband multiresonance metasurface antenna based on characteristic mode analysis

ABSTRACT A multiresonance metasurface antenna for C-band application is proposed in this paper. A broadband metasurface with consistent radiation performance is designed using characteristic mode analysis (CMA). The metasurface is formed by 4 × 4 square patches, and circular slots of different radius are etched on the center and edge patches. To achieve consistent radiation, the size of circular slots on the corner patches is increased. The metasurface is excited by slot antenna, and multiple adjacent resonant frequencies are generated by combining two modes of the metasurface and resonant mode of slot antenna. The measured results show that the −10 dB impedance bandwidth of the antenna is 4.22–8.38 GHz (66%), and the peak gain is 8.2 dBi.

Inverse design of dual-bandpass metasurface filters empowered by the multi-objective genetic algorithm

Multi-band metasurface filters are becoming increasingly pivotal in high-capacity communication technologies. Traditional methods for designing metasurface structures, to date, have relied on empirical approaches to obtain target electromagnetic responses, thereby suffering from low efficiency. Here, we demonstrate an advanced approach for the inverse design of a multi-band metasurface filter, which consists of a multi-objective genetic algorithm (MOGA) in tandem with equivalent circuit model (ECM) analysis. This integration converts specific frequency response requirements into ECM parameter constraints, significantly streamlining the metasurface design and optimization process and offering superior solutions. Using this inverse design method, we theoretically propose a dual-bandpass metasurface filter which can exhibit transmission passbands in any two adjacent frequency ranges among the X-, Ku-, and K-bands. Further, numerical simulations validate the performances of the proposed device, which show great agreement with MOGA-based predictions. Our results pave the way to the effective inverse design of multi-passband metasurface filters which are useful in many applications, such as microwave filters, radar and satellite communication systems, and radio frequency identification devices.

A seismic thin‐layer detection factor calculated by integrated S transform with non‐negative matrix factorization

AbstractTime–frequency analysis is one of the effective methods for seismic thin‐layer detection. Conventional time–frequency analysis technology for seismic thin‐layer detection is interfered by the energy of adjacent frequency signals, and there is information redundancy in the frequency‐domain analysis. Therefore, an S transform with improved window factor, which is based on the constrained non‐negative matrix factorization, is constructed to realize seismic thin‐layer detection. First, the seismic data is processed by the S transform of the improved window factor, and then we can obtain the frequency‐domain information with strong time–frequency focus by changing the adjustment factor and attenuation factor in the window function. Furthermore, the key frequency of the seismic data spectrum, which can also be called the key frequency characteristic factor, can be calculated by the non‐negative matrix factorization algorithm. Fortunately, the overthrust model shows a good correspondence between the key frequency characteristic factor and the thin‐layer interface. The field data example shows that this approach provides a new approach for thin‐layer detection.

Effect of Piracetam and Iron Treatment on Heart Rate Variability in Patients With Breath-Holding Spell

BackgroundBreath-holding spells are a benign condition primarily seen in 3% to 5% of healthy children aged between six months and five years. Although no specific treatment is recommended due to its benign nature, iron and piracetam are used in severe or recurrent cases. We planned to compare the heart rate variability (HRV) before and after treatment with 24-hour Holter monitoring in patients receiving iron and piracetam treatment and investigate the treatment's effectiveness. MethodsTwenty-five patients who applied to the outpatient clinic between 2013 and 2015 due to breath-holding spells were included in the study. The patients who received piracetam and iron therapy and underwent 24-hour rhythm Holter monitoring were evaluated retrospectively. ResultsFourteen (56%) of these patients were evaluated as having cyanotic-type and 11 (44%) patients were assessed as having pale-type breath-holding spells. A significant difference was found only between hourly peak heart rate and total power in the group receiving iron treatment. Significant differences were also found among the minimum heart rate, mean heart rate, the standard deviation of RR intervals, the mean square root of the sum of the squares of their difference between adjacent RR intervals, spectpow, and low frequency before and after the treatment in the patients who started piracetam treatment (P < 0.05). ConclusionsOur study is critical as it is the first to investigate the effects of treatment options on various HRV in patients with breath-holding spells. There were statistically significant changes in HRV parameters in patients receiving piracetam, and the number of attacks decreased significantly. Piracetam treatment contributes positively to the breath-holding spell with regard to efficacy and HRV, therefore it can be used to treat breath-holding spells.

Idiopathic sudden sensorineural hearing loss: A trial of modified Stennert’s infusion therapy

Introduction and Aim: Sudden sensorineural hearing loss presents as rapid onset hearing deterioration of more than 30dB within 72 hours at the minimum of three adjacent frequencies. The aim of this research was to determine the effect of Modified Stennert’s Protocol in addressing idiopathic sudden sensorineural hearing loss. Materials and Methods: Retrospective pilot study was done. 14 patients were started on Modified Stennert’s protocol within 72 hours of onset of symptoms and were observed. Our modification included using hydrocortisone instead of prednisolone. Results: All patients presenting with sudden sensorineural hearing loss showed significant improvement in hearing by the end of two weeks and at the end of 3 months. Conclusion: With such obscured pathophysiology, treatment of modified versions of usage of hydrocortisone instead of prednisolone along with dextran and pentoxyfylline has shown prime augmentation towards the patients resulting in near normal hearing.

Efficient prediction of individual head-related transfer functions based on 3D meshes

Individual head-related transfer functions (HRTFs) are critical for binaural spatial audio rendering. In contrast to anthropometric parameters and pinnae images, 3D meshes allow for a more direct and comprehensive representation of the anthropometric structure, which provides highly effective inputs for modeling individualized HRTFs. This paper presents a neural network-based method for predicting individualized HRTFs in full space based on 3D meshes. Unlike many previous methods that estimate HRTF spectra at sampling grids or frequencies separately, the proposed model predicts the HRTF spectra of each vertical plane by considering the spectral correlation and continuity across adjacent sampling grids and frequencies. Evaluation results indicate that the proposed method enhances the prominence of peaks and notches in the obtained HRTF spectra and improves the speed and accuracy of HRTF individualization. The log spectral distortion of the proposed method is lower than that of state-of-the-art methods using anthropometric parameters and pinnae images. Further evaluation confirms that the proposed method requires significantly fewer points in 3D meshes when compared to numerical simulation methods. The evaluation based on localization models demonstrates that the HRTFs predicted by the proposed method are perceptually similar to the measured HRTFs.

GNSS interference monitoring and detection based on the Swedish CORS network SWEPOS

Abstract The presence of Global Navigation Satellite System (GNSS) interference poses a significant risk to both GNSS and the infrastructures that depend on them. This article describes how an existing GNSS infrastructure, the Swedish Continuously Operating Reference Stations network SWEPOS with more than 500 stations, can be leveraged to control the quality of GNSS signals and to be able to detect interferences in GNSS and adjacent frequency bands. This study introduces a SWEPOS-based automatic system that effectively detects GNSS interference by examining the signal-to-noise ratio (SNR) of Global Positioning System, Globalnaya Navigatsionnaya Sputnikovaya Sistema, Galileo, and BeiDou frequency bands. By comparing the SNR of tracked satellites against historical data, the system detects radio frequency interference (RFI) by statistically characterizing the SNR of simultaneously tracked satellites. Furthermore, based on the SNR characteristics across satellites, the system distinguishes between RFI and non-RFI sources. The effectiveness of the detection system is demonstrated through both simulated signal interference waves and real-world interference events.