Search Results (10)

We investigate a combined conservative field, in which classical gravitational and electrostatic sources also exhibit mutual interactions. Hitherto neglected, the coupling between mass and charge may be necessary for constructing a unified conservative force field generated by a single underlying source. We determine the coupling constant of the cross-field components as the geometric mean (G-M) of Newton’s G and Coulomb’s K constants, in both SI units and dimensionless form. Consequently, for two identical objects, the cross-force ($F_{\times }$) is the G-M of the familiar Newton ($F_{\mathrm{g}}$) and Coulomb ($F_{\mathrm{e}}$) forces, so that $F_{\times }=\sqrt{F_{\mathrm{g}}{F}_{\mathrm{e}}}$, where $F_{\mathrm{g}}\ll F_{\times }\ll F_{\mathrm{e}}$. Remarkably, such cross-forces should be measurable in torsion balance experiments involving a suspended neutral mass interacting with a partially ionized gas. Furthermore, we apply our new formulation to estimate the dimensionless amplitude $\parallel {\mathcal{h}}_{\alpha \beta }^{\mathrm{TT}}\parallel$ of gravitational waves that are emitted by inspiraling Reissner–Nordström (RN) black hole binaries, expressed in terms of ratios of the four fundamental lengths of the problem: the distance to the binary D, the binary separation R, the Schwarzschild radius $R_S\propto 2M$ of mass M, and the RN charge (Q) length scale $L_Q\propto 2Q$. In this classical setting with speeds much lower than the speed of light c in vacuum, the surprising appearance of the maximum relativistic tension force $F_{\max }=c^4/\left(4G\right)$ is duly noted. Full article

In recent years, global agriculture has encountered several challenges exacerbated by the effects of changes in climate, such as extreme water shortages for irrigation and heat waves. Water-deficit stress adversely affects the morpho-physiology of numerous crops, including soybean (Glycine max L.), which is considered as promising crop in Bangladesh. Seaweed extract (SWE) has the potential to improve crop yield and alleviate the adverse effects of water-deficit stress. Remote and proximal sensing are also extensively utilized in estimating morpho-physiological traits owing to their cost-efficiency and non-destructive characteristics. The study was carried out to evaluate soybean morpho-physiological traits under the application of water extracts of Gracilaria tenuistipitata var. liui (red seaweed) with two varying irrigation water conditions (100% of total crop water requirement (TCWR) and 70% of TCWR). Principal component analysis (PCA) revealed that among the four treatments, the 70% irrigation + 5% (v/v) SWE and the 100% irrigation treatments overlapped, indicating that the application of SWE effectively mitigated water-deficit stress in soybeans. This result demonstrates that the foliar application of 5% SWE enabled soybeans to achieve morpho-physiological performance comparable to that of fully irrigated plants while reducing irrigation water use by 30%. Based on Pearson’s correlation matrix, a simple linear regression model was used to ascertain the relationship between unmanned aerial vehicle (UAV)-derived vegetation indices and the field-measured physiological characteristics of soybean. The Normalized Difference Red Edge (NDRE) strongly correlated with stomatal conductance (R² = 0.76), photosystem II efficiency (R² = 0.78), maximum fluorescence (R² = 0.64), and apparent transpiration rate (R² = 0.69). The Soil Adjusted Vegetation Index (SAVI) had the highest correlation with leaf relative water content (R² = 0.87), the Blue Normalized Difference Vegetation Index (bNDVI) with steady-state fluorescence (R² = 0.56) and vapor pressure deficit (R² = 0.74), and the Green Normalized Difference Vegetation Index (gNDVI) with chlorophyll content (R² = 0.73). Our results demonstrate how UAV and physiological data can be integrated to improve precision soybean farming and support sustainable soybean production under water-deficit stress. Full article

Background/Objectives: This study aimed to evaluate the results of continuous intracranial pressure (ICP) monitoring in children with macrocephaly or rapidly increasing head circumference (HC) diagnosed as benign external hydrocephalus (BEH). Here, we report the absolute ICP measurements, ICP pulsatility, and slow ICP waves after at least 48 h of continuous monitoring in a cohort of 36 children diagnosed with BEH. Methods: A prospective study of continuous ICP monitoring was performed in 36 consecutive children with macrocephaly (HC above the 97.5th percentile) or rapidly increasing HC (at least crossing two percentile curves), diagnosed with BEH (22 boys and 14 girls with a mean age of 23.6 ± 13.3 months, minimum: 6, maximum 65), using an epidural sensor. For the first four children in the study, hard copies of the ICP values were obtained using an analog recorder. Starting from the fifth patient, the ICP signal was sampled at 200 Hz and stored on a computer using a computer-based data acquisition and analysis system (LabChart v8.1 software). Results: Clinical signs or symptoms were identified in 20 patients (55.6%). Delayed motor or language development was noted in 18 (50%) and 20 (55.6%) patients, respectively. In 13 patients, the enlargement of the subarachnoid spaces was found to be associated with an additional condition. The median of mean ICP values for the entire cohort was 17 mmHg, with a minimum of 6.7 mmHg and a maximum of 29 mmHg. All patients exhibited a percentage of B waves exceeding 20% during the night, with a median value of 47.4% (min: 23.2, max: 75). Three children had nocturnal plateau waves. At night, regular ICP recordings alternated with periods of significant increases in ICP, often exceeding 10 mmHg above baseline values. High-amplitude B waves were noted during these episodes, and the amplitude of the cardiac waveform at the peak of the B waves was consistently greater than 5 mmHg, displaying an abnormal morphology (P2 > P1). A ventriculoperitoneal shunt was implanted in 30 of the 36 patients. Conclusions: Patients with BEH may present significant abnormalities in ICP. Monitoring this variable in certain cases can assist in determining the necessity for surgical treatment. Full article

High-resolution optical multidimensional coherent spectroscopy (MDCS) requires frequency-stable laser sources and high-resolution heterodyne spectra. Fully phase-locked dual-comb spectroscopy (DCS) enables the achievement of high resolution, high accuracy, broad bandwidth, and a rapid multi-heterodyne spectrum, which results in the DCS’s potential to replace the spectrometer and phase detection system in MDCS. We verified the phase measurement capability of the MDCS system based on fully phase-locked fiber DCS by studying phase-sensitive photon echoes and double-quantum processes. The accurate phase and frequency of linear and nonlinear signals were obtained simultaneously using a single detector without subsequent frequency drift correction. Subsequently, the acquisition of longtime quantum beat signals demonstrates the high phase coherence between excitation pulses. Additionally, the two-dimensional coherent spectrum (2DCS) with high signal-to-noise-ratio and 100 MHz resolution was obtained via the MDCS system based on fully phase-locked fiber DCS. These results exhibit that fully phase-locked fiber DCS is an effective method for high-resolution 2DCS measurement, which facilitates further research on cold atoms, higher-order nonlinear spectra, and molecular fingerprint vibrational spectroscopy. Full article

In order to yield more Co(II), 2,6-diaminopyridine (DAP) was polymerized with 4,4-methylene diphenyl diisocyanates (MDI) in the presence of Co(II) to obtain a Co-complexed polyurea (Co-PUr). The obtained Co-PUr was calcined to become Co, N-doped carbon (Co–N–C) as the cathode catalyst of an anion exchange membrane fuel cell (AEMFC). High-resolution transmission electron microscopy (HR-TEM) of Co–N–C indicated many Co-Nx (Co covalent bonding with several nitrogen) units in the Co–N–C matrix. X-ray diffraction patterns showed that carbon and cobalt crystallized in the Co–N–C catalysts. The Raman spectra showed that the carbon matrix of Co–N–C became ordered with increased calcination temperature. The surface area (dominated by micropores) of Co–N–Cs also increased with the calcination temperature. The non-precious Co–N–C demonstrated comparable electrochemical properties (oxygen reduction reaction: ORR) to commercial precious Pt/C, such as high on-set and half-wave voltages, high limited reduction current density, and lower Tafel slope. The number of electrons transferred in the cathode was close to four, indicating complete ORR. The max. power density (P_max) of the single cell with the Co–N–C cathode catalyst demonstrated a high value of 227.7 mWcm⁻². Full article

When ground penetrating radar (GPR) is used for the non-destructive evaluation of concrete bridge decks, the rebar reflection amplitudes should be corrected for rebar depths to account for the geometric spreading and material attenuation of the electromagnetic wave in concrete. Most current depth-correction methods assume a constant EM wave velocity in the entire bridge deck and correct GPR amplitudes based on the two-way travel time (TWTT) instead of the actual rebar depth. In this paper, we proposed a depth-correction algorithm based on the real rebar depths. To compare different depth-correction methods, we used gprMax software to simulate GPR signals in four models with various dielectric constants and conductivity. The comparison shows that the TWTT-based depth-correction method tends to over-correct GPR amplitudes so that underestimates the deterioration level of concrete decks at certain locations. Two depth-based correction methods are proposed that use migrated amplitudes and further normalize the corrected amplitude by rebar depth (attenuation rate). These methods are then applied to GPR data collected on two bridges, and the results were validated by other NDE methods and chloride concentration test. Full article

A four-port dielectric resonator (DR)-based multiple-input multiple-output (MIMO) antenna is presented for sub-6 GHz MIMO communication. The dielectric resonator was fed through aperture feeding to achieve dual-band resonance. The DRA has the operating modes of $T{E}_{01\delta }$ and $T{E}_{10\delta }$at 3.3 GHz and 3.9 GHz, respectively. The engineered antenna has port isolation of higher than 20 dB at the target frequencies without the employment of an extra isolation mechanism. Full-wave high-frequency simulation software was employed for the simulation computation. The antenna has a peak gain of 5.8 dBi and 6.2 dBi, and an efficiency of 88.6% and 90.2% at 3.3 GHz and 3.9 GHz, respectively. The proposed resonator has good MIMO diversity parameters. The optimal envelope correlation coefficient (ECC) is 0.01, channel capacity loss (CCL) is 0.1 bits/sec/Hz, and the total active reflection coefficient (TARC) is −22.46. The DRA elements are aligned orthogonally with adequate displacement for achieving polarization diversity and spatial diversity. The antenna delivers its applications in Sub-6 GHz 5G and WiMAX communications. Full article

One of the most common revetment types in Germany is the mortar-grouted riprap revetment (MGRR), which is constructed by placing riprap on a filter or separation layer and subsequent grouting with mortar. Existing technical standards and guidelines for MGRRs do not consider the interaction between dynamic wave loading and structural response. To date, scientifically sound design approaches verified by model tests are missing. Therefore, the aim of this work is to establish a process-based model for the calculation of the acting bending tensile stresses during wave attack for MGRRs to asses crack formation. To this end, MGRRs were modelled as plates on an elastic foundation (PEF). Hydraulic boundary conditions were determined with full-scale hydraulic model tests. Model parameters of the PEF model were established by investigations into the mechanical parameters of the constituents of MGRRs. The results show that tensile bending stresses are particularly dependent on the pressure difference between the top and bottom edge of the top layer, which varies significantly for MGRRs as their porosity and permeability varies significantly depending on the amount of mortar used for grouting. Enveloping functions for maximum relative tensile bending stress σ_x,max/(ρ_wgH_m0) are given for four configurations of MGRRs that are of great practical relevance. Full article

In the paper, we present a novel approach to the optimum design of wearable antenna arrays intended for off-body links of wireless body area networks. Specifically, we investigate a four-element array that has a switchable radiation pattern able to direct its higher gain towards a signal source and a lower gain towards an interference. The aim is to increase the signal to interference ratio. We apply a genetic algorithm to optimize both the spatial placement and the feed phasing of the elementary on-body antennas. We propose a simplified, computationally efficient model for the simulation of the array radiation pattern. The model is based on full-wave simulations obtained with a simplified cylindrical model of the human body. We also propose, implement, and evaluate four objective functions based on signal to interference ratio, i.e., min-max, nadir point distance maximization, utopia point distance minimization, and full Pareto-like. Our optimized design obtained with this approach exhibits a significant performance improvement in comparison to the initial heuristic design. Full article

InGaN/GaN samples grown on c-plane sapphire substrate with different In concentrations by metal organic chemical vapor deposition are demonstrated. The subsequent capping GaN layer growth opens a possibility for dislocation reduction due to the lateral strain relaxation in growth geometry. We present the further growth optimization and innovative characterization of InGaN layers overgrown on different structures with varying In concentrations. The photoelectrical and optical properties of the InGaN layers with/without capping GaN layer are investigated by time-resolved picosecond transient grating and temperature dependence photoluminescence. We note a 10-fold increase in carrier lifetime in the InGaN layers when the sample structure changed from PIN to single InGaN layer. Full article