Nearby Bands Research Articles

Superconductivity in Twisted WSe_{2} from Topology-Induced Quantum Fluctuations.

Recently, superconductivity has been observed in twisted WSe_{2} moiré structures (Xia etal., Nature (London) 637, 833 (2025)NATUAS0028-083610.1038/s41586-024-08116-2; Guo etal., Nature (London) 637, 839 (2025)NATUAS0028-083610.1038/s41586-024-08381-1). Its transition temperature is high, reaching a few percent of the Fermi temperature scale. Here, we advance a mechanism for superconductivity based on the notion that electronic topology enables quantum fluctuations in a suitable regime of intermediate correlations. In this regime, the Coulomb interaction requires that an active topological flat band and nearby wider bands are considered together. Compact molecular orbitals arise, which give rise to quantum fluctuations through topology-dictated hybridization with the other molecular orbitals. The hybridization competes with the active flat band's natural tendency toward static electronic ordering, thereby weakening the latter; we link this effect with certain salient observations by experiments. Furthermore, the competition yields a quantum critical regime where quasiparticles are lost. The corresponding quantum critical fluctuations drive superconductivity. Broader implications and new connections among correlated materials platforms are discussed.

Resolving Asymmetric Spectral Bands

AbstractThis paper introduces the basics of asymmetrical spectral band fitting and discusses the resolution of overlapping Gaussian shapes. We study how to fit overlapping bands with asymmetric Gaussian shapes. First, we derive an equation for an Asymmetric Gaussian shape. We then use this equation to derive a resolvability basis for the resolution of two nearby Gaussian bands. The so called Master Equation is then used to fit these two overlapping bands. We identify regions of the fitting space where the Asymmetric Gaussian fit is likely to be Optimal, Sub Optimal and Not Optimal. We then demonstrate the use of the Asymmetric Gaussian to fit four overlapping bands, and show how this is relevant to the olivine spectral complex at 1 m. The limitations of the asymmetric band fitting method and a critical assessment of three commonly used numerical minimization and fitting methods are also provided.

DSSFN: A Dual-Stream Self-Attention Fusion Network for Effective Hyperspectral Image Classification

Hyperspectral images possess a continuous and analogous spectral nature, enabling the classification of distinctive information by analyzing the subtle variations between adjacent spectra. Meanwhile, a hyperspectral dataset includes redundant and noisy information in addition to larger dimensions, which is the primary barrier preventing its use for land cover categorization. Despite the excellent feature extraction capability exhibited by convolutional neural networks, its efficacy is restricted by the constrained receptive field and the inability to acquire long-range features due to the limited size of the convolutional kernels. We construct a dual-stream self-attention fusion network (DSSFN) that combines spectral and spatial information in order to achieve the deep mining of global information via a self-attention mechanism. In addition, dimensionality reduction is required to reduce redundant data and eliminate noisy bands, hence enhancing the performance of hyperspectral classification. A unique band selection algorithm is proposed in this study. This algorithm, which is based on a sliding window grouped normalized matching filter for nearby bands (SWGMF), can minimize the dimensionality of the data while preserving the corresponding spectral information. Comprehensive experiments are carried out on four well-known hyperspectral datasets, where the proposed DSSFN achieves higher classification results in terms of overall accuracy (OA), average accuracy (AA), and kappa than previous approaches. A variety of trials verify the superiority and huge potential of DSSFN.

Optimal Channel Selection algorithm for CRahNs

Optimal Channel Selection algorithm for CRahNs

Electrically small, low‐profile, full‐duplex Huygens dipole filtenna

AbstractAn electrically small, full‐duplex Huygens dipole filtenna (HDF) is realized as a dense array of two HDF elements consisting of Egyptian axe dipole and capacitively‐loaded loop near‐field resonant parasitic (NFRP) elements. The dual‐band HDF elements operate at two very nearby frequency bands and are physically separated by only 0.12 λLB. Benefitting from the HDF element's good out‐of‐band rejection performance characteristics, high isolation levels between the lower‐band (LB) and higher‐band (HB) ports are obtained without any decoupling structure. The measured results, in good agreement with their simulated values, demonstrate that the entire system is electrically small (ka = 0.975) and low‐profile (0.041 λLB). The measured isolation levels at its LB (HB) port is, respectively, over 33.9 (29.2) dB. When the LB (HB) port is excited, its fractional bandwidth, broadside realized gain, front‐to‐back ratio, and overall efficiency values are, respectively, 0.86% (0.77%), 2.1 (2.31) dBi, 8.1 (9.6 ) dB, and 62.1% (62.8%).

Possible Use of MIMO/Massive MIMO Technology to Increase Spectrum Access by Controlling Interservice Interference

Most wireless technology researchers view obtaining access to spectrum as a specialty for others who focus solely in spectrum policy. Thus, the researcher finds out from others what bands are available for their application. In many cases, the question of whether band x can be used for application <tex>$y$</tex> ultimately depends on whether this application in this band will cause interference to other users in either the same band or nearby bands. This type of problem is usually approached by developing power budgets for both the desired transmitter to desired receiver path as well as from the new band user transmitter to incumbent receiver path and checking what the desired-to-undesired-signal ratios are and whether they will result in harmful interference. Generally, the design of equipment for new spectrum uses has not been greatly influenced by the need to protect incumbent spectrum uses. Rather, spectrum regulators often base use decisions on traditional technology and whether such technology might result in interservice interference to incumbent systems.

Accessory laboratory measurements to support quantification of hydrogen isotopes by in-situ LIBS from a robotic arm inside a fusion vessel

Accessory laboratory measurements to support quantification of hydrogen isotopes by in-situ LIBS from a robotic arm inside a fusion vessel

Broadband terahertz transmissive quarter-wave metasurface

Polarization conversion devices are key components in spectroscopy and wireless communications systems. Conventional terahertz waveplates made of natural birefringent materials typically suffer from low efficiency, narrow bandwidth, and substantial thickness. To overcome the limitations associated with conventional waveplates, a terahertz quarter-wave metasurface with enhanced efficiency and wide bandwidth is proposed. The transmissive quarter-wave metasurface is rigorously designed based on an extended semi-analytical approach employing network analysis and genetic algorithm. Simulation results suggest that the design can achieve linear-to-circular polarization conversion with a 3-dB axial ratio relative bandwidth of 53.3%, spanning 205 GHz–354 GHz. The measurement results confirm that the proposed design enables a 3-dB axial ratio from 205 GHz to at least 340 GHz with a total efficiency beyond 70.2%, where the upper frequency bound is limited by the available experimental facility. This quarter-wave metasurface can cover an entire terahertz electronics band and can be scaled to cover other nearby bands under the same convention, which are technologically significant for future portable systems.

Distortion of protein analysis in primary neuronal cultures by serum albumin from culture medium: A methodological approach to improve target protein quantification

Distortion of protein analysis in primary neuronal cultures by serum albumin from culture medium: A methodological approach to improve target protein quantification

Nyílt rendszerű magmás folyamatok: magmakeveredés, kristálycsere és kumulátum-recirkuláció nyomai a Ditrói alkáli masszívumban (Orotva, Románia)

A Tarniţa Komplexum a Keleti-Kárpátokban (Románia) felszínre bukkanó Ditrói alkáli masszívum északi területének jellemző ultramafikus és mafikus kőzetegyüttese. A komplexum Ny-i részén, az Orotva-patak és a Felső-Pietrăriei-patak összefolyásánál található mélységi magmás kőzettestben kialakított mesterséges feltárás egyedülálló betekintést enged az egykori magmatározóban zajlott, több magma között lejátszódott keveredési és elegyedési folya matokba, illetve az új magmabenyomulások során feltépett, korábban kikristályosodott magmás kőzetfragmen tumok bekeveredési folya mataiba. A feltárásban látható befogadó kőzetben (szürke, közép- és durvaszemcsés, irányított szövetű diorit) négy különböző keveredési kőzetzárvány (mafikus kőzetzárvány; földpátszemes kőzetzárvány; porfíros (földpátaggregátumos), mafikus kőzetzárvány és ultramafikus kőzetzárvány) és egy eltérő eredetű felzikus kőzetzárvány típus figyelhető meg. A keveredési kőzetzárványok modális összetételük alapján mezokrata és melanokrata dioritok, valamint piroxénhorn blenditek, a felzikus kőzetzárványok pedig hololeukokrata dioritok. A különböző magmák közötti keveredés (mingling) legfontosabb bélyege az egymással — és a befogadó kőzet ásványainak orientált elhelyezkedésével — párhuzamos, megnyúlt, finomszemcsés, lencse alakú kőzetzárványok meg jele nése. A szögletes felzikus xenolitok és ultramafikus kőzetzárványok korábbi kumulátumok recirkulációját felté telezik, amelyek a benyomuló magmával kerültek a magmatározóba. A keveredési kőzetzárványok mafikus pereme és a közelükben megfigyelhető „slírek” további fontos jellemzői a legalább két magma keveredése során kialakuló szerke ze teknek. A magmaelegyedés gyakori velejárója a kristálycsere (crystal transfer). A vizsgált ásványok számos esetben mutatnak olyan jellegzetes mikroszöveti bélyegeket, amelyek e kristálycsere-folyamathoz köthetők a benyomuló és a befogadó magma, illetve a benyomuló magma és a feltépett kumulátumok között: a különféle zónásságot mutató és különbözőzárványgazdag plagioklászok, az amfibolköpennyel rendelkező piroxének és a plagioklászokban megjelenő tűs apatit kristályok. A jelen tanulmányban bemutatott részletes petrográfiai vizsgálatok rávilágítanak a Ditrói alkáli masszívum magmatározóinak összetett és változatos fejlődéstörténetére, amelyben meghatározó szerepet játszottak a nyílt rendszerű magmás folyamatok.

Dual-Band Circularly Polarized Antenna With Wide Axial Ratio Beamwidths for Upper Hemispherical Coverage

This paper presents a dual-band circularly polarized cross-dipole antenna with wide axial ratio beamwidths for full upper hemispherical coverage for GPS L1 and L2 bands. The antenna has curved radiating arms and a corrugated back cavity to enhance the beamwidth. A wideband hybrid coupler is used to feed the antenna at the two nearby frequency bands. Experimental results show that very wide 3-dB AR beamwidths of over 200° can be obtained, fully covering the upper hemisphere for the two GPS bands.

The all-sky medium energy gamma-ray observatory

The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is an Astrophysics Probe mission concept designed to explore the MeV sky. It has a unique capability to cover with high sensitivity both the Compton and pair conversion regimes from ∼ 200 keV to > 10 GeV . To date the MeV regime was explored with significantly less sensitivity with respect to the nearby energy bands, and promises a rich return similar to what Fermi-LAT achieved in the GeV band. The AMEGO instrument features an anti-coincidence detector, a double-sided Silicon microstrip tracker with analog readout, a segmented CZT calorimeter optimized for the Compton regime, and a segmented CsI calorimeter optimized for the pair regime. This design choice provides substantial performance improvements relative to CGRO-COMPTEL and Fermi-LAT in the overlapping energy bands. In particular, the detector is tailored to the challenging task of imaging Compton events with unprecedented resolution.

Unlicensed Operations in the 600 MHz Guard Bands: Potential Impact of Interference on the Outcome of the Incentive Auction

Unlicensed Operations in the 600 MHz Guard Bands: Potential Impact of Interference on the Outcome of the Incentive Auction

Strongly bound excitons in gapless two-dimensional structures

Common wisdom asserts that bound excitons cannot form in high-dimensional (d>1) metallic structures because of their overwhelming screening and unavoidable resonance with nearby continuous bands. Strikingly, here we illustrate that this prevalent assumption is not quite true. A key ingredient that has been overlooked is that of viable decoherence that thwarts the formation of resonances. As an example of this general mechanism, we focus on an experimentally relevant material and predict bound excitons in twisted bilayer graphene, which is a two-dimensional gapless structure exhibiting metallic screening. The binding energies calculated by first-principles simulations are surprisingly large. The low-energy effective model reveals that these bound states are produced by a unique destructive coherence between two alike subband resonant excitons. In particular, this destructive coherent effect is not sensitive to the screening and dimensionality, and hence may persist as a general mechanism for creating bound excitons in various metallic structures, opening the door for excitonic applications based on metallic structures.

Evaluation of the NIR-SWIR atmospheric correction algorithm for MODIS-Aqua over the Eastern China Seas

The performance of the near-infrared (NIR) and short-wave infrared (SWIR) combined atmospheric correction algorithm (NIR-SWIR) for Moderate Resolution Imaging Spectroradiometer (MODIS)-Aqua over the Eastern China Seas (ECS) was evaluated. The in situ data set for evaluation in this study was collected during 2005 and 2012 through eight cruises in the ECS, wherein 49 in situ observation points were successfully matched with MODIS-Aqua data. The remote-sensing reflectance derived from MODIS-Aqua data using the NIR-SWIR algorithm and the NIR algorithm were compared to the in situ measurements in the matched-up data set, which included ocean bands (412, 443, 488, 531, 547, 667, and 678 nm) and land bands (469, 555, and 645 nm). The results show that the performance of the NIR-SWIR algorithm has been improved in turbid waters, and the effect at the short-wave bands (blue and green bands) is more significant than that at the long-wave bands (red bands). In addition, MODIS-Aqua data at the land bands (469, 555, and 645 nm) show a similar performance to those of nearby ocean bands. However, the lower estimation accuracy is still a remarkable question at bands 412, 645, 667, 678 nm. The results from both the NIR-SWIR and NIR algorithms were applied to the images of MODIS-Aqua in the ECS and they indicate that the extent to which the quality of the derived remote-sensing reflectance using the NIR-SWIR algorithm can be improved shows major differences for different seasons. The minimum area is in summer, and the maximum area in winter. The NIR-SWIR algorithm should be used for the whole of the Bohai Sea in winter.

The impact of the Kasatochi eruption on the Moon's illumination during the August 2008 lunar eclipse

The Moon's changeable aspect during a lunar eclipse is largely attributable to variations in the refracted unscattered sunlight absorbed by the terrestrial atmosphere that occur as the satellite crosses the Earth's shadow. The contribution to the Moon's aspect from sunlight scattered at the Earth's terminator is generally deemed minor. However, our analysis of a published spectrum of the 16 August 2008 lunar eclipse shows that diffuse sunlight is a major component of the measured spectrum at wavelengths shorter than 600 nm. The conclusion is supported by two distinct features, namely the spectrum's tail at short wavelengths and the unequal absorption by an oxygen collisional complex at two nearby bands. Our findings are consistent with the presence of the volcanic cloud reported at high northern latitudes following the 7-8 August 2008 eruption in Alaska of the Kasatochi volcano. The cloud both attenuates the unscattered sunlight and enhances moderately the scattered component, thus modifying the contrast between the two contributions.

A Dual-Band Epsilon-Negative Material Design Using Folded-Wire Structures

A novel design of epsilon-negative (ENG) material which can exhibit negative permittivity at two nearby bands is presented in this paper. With the unit shape as an unsealed rectangle frame, the components of this ENG material are two folded wires with different dimensions. Each folded-wire structure can achieve electric resonance at a certain frequency band by appropriately adjusting its dimensions. Its electromagnetic properties are then retrieved to demonstrate that the dual-band electric resonances can be obtained in our sample. With the aid of numerical simulation, the transmission property of the proposed dual-band epsilon-negative material is further investigated. And the result shows that the stop band for each folded wire (permittivity ε < 0) is easily adjusted by changing the designing parameters, without influence on the other nearby resonance frequency. It provides an advancement of dual-band and low mutual coupling resonances design. It is also promising that our approach will be effective to make this kind of dual-band ENG material applied into the areas of reconfigurable antennas and their arrays.

Analysis of a simplified normalized covariance measure based on binary weighting functions for predicting the intelligibility of noise-suppressed speech

The normalized covariance measure (NCM) has been shown previously to predict reliably the intelligibility of noise-suppressed speech containing non-linear distortions. This study analyzes a simplified NCM measure that requires only a small number of bands (not necessarily contiguous) and uses simple binary (1 or 0) weighting functions. The rationale behind the use of a small number of bands is to account for the fact that the spectral information contained in contiguous or nearby bands is correlated and redundant. The modified NCM measure was evaluated with speech intelligibility scores obtained by normal-hearing listeners in 72 noisy conditions involving noise-suppressed speech corrupted by four different types of maskers (car, babble, train, and street interferences). High correlation (r = 0.8) was obtained with the modified NCM measure even when only one band was used. Further analysis revealed a masker-specific pattern of correlations when only one band was used, and bands with low correlation signified the corresponding envelopes that have been severely distorted by the noise-suppression algorithm and/or the masker. Correlation improved to r = 0.84 when only two disjoint bands (centered at 325 and 1874 Hz) were used. Even further improvements in correlation (r = 0.85) were obtained when three or four lower-frequency (<700 Hz) bands were selected.

Vibrational Spectroscopy and Dynamics of the Hydrazoic and Isothiocyanic Acids in Water and Methanol

Small anions in polar solvents are benchmark systems for fast vibrational energy relaxation (VER) due to the Coulombic effects that promote solute-solvent interactions. In order to investigate the effects of solute charge and solvent isotope effects on vibrational spectra and dynamics, infrared pump-probe studies have been used to determine VER (T(1)) times for the pseudohalide acids, XNCS and XN(3) (X = H, D), in protic solvents, H(2)O, D(2)O, CH(3)OH, and CD(3)OD. These results are compared with the well-studied azide and thiocyanate anions. Solvent isotope effects of the vibrational frequency shifts of azide and for VER rates of both azide and thiocyanate are similar to those for the hydro- and deutero-protonated species in water. VER times are longer for HN(3)/H(2)O, HN(3)/CH(3)OH, and DN(3)/CD(3)OD (T(1) = 2.3, 5.6, and 3.7 ps, respectively) than for the corresponding anions in solution (0.8, 3.0, and 2.1 ps), which is consistent with the idea that ions relax more quickly than neutrals. But the times measured for DN(3)/D(2)O, HNCS/H(2)O, and DNCS/D(2)O (T(1) = 1.2, 1.5, and 4.4 ps, respectively) are shorter than for the corresponding ions (2.3, 2.7, and 22.0 ps). Fast VER for DN(3) in D(2)O is attributed to strong coupling to nearby solvent bands and/or to Fermi resonances that promote intramolecular vibrational relaxation. For the HNCS and DNCS, the faster rates can be understood by recognizing that the charge displacements are similar to those for the anion.

Mg and TiO spectral features at the near-IR: spectrophotometric index definitions and empirical calibrations

Using the near-infrared spectral stellar library of Cenarro et al. (2001a,b), the behaviours of the Mg I line at 8807 angstrom and nearby TiO bands are analyzed in terms of the effective temperature, surface gravity, and metallicity of the library stars. New spectroscopic indices for both spectral features -namely MgI and sTiO- are defined, and their sensitivities to different signal-to-noise ratios, spectral resolutions, flux calibrations, and sky emission line residuals are characterized. The new two indices exhibit interesting properties. In particular, MgI reveals as a good indicator of the Mg abundance, whereas sTiO is a powerful dwarf-to-giant discriminator for cold spectral types. Empirical fitting polynomials that reproduce the strength of the new indices as a function of the stellar atmospheric parameters are computed, and a FORTRAN routine with the fitting functions predictions is made available. A thorough study of several error sources, non-solar [Mg/Fe] ratios, and their influence on the fitting function residuals is also presented. From this analysis, a [Mg/Fe] underabundance of ~ -0.04 is derived for the Galactic open cluster M67.