Transverse Scale Research Articles

A new species of Macropodus (Teleotsei: Osphronemidae) from Fujian Province, southern China

A new Macropodus species was collected from the river basins of southeastern China. The new species Macropodus minnanensis, from Fujian Province, China can be well distinguished from congeners by the following combination of features: (1) dorsal fin with 13 spines and 7 soft rays; (2) anal fin with 20 spines and modally 10 soft rays; (3) vertical insertion of dorsal fin origin at second to third soft rays of anal fin; (4) longitudinal scale rows in midline modally 28; (5) transverse scale rows 14; (6) vertebrae 27 and (7) specific coloration: body with posteriorly black margin on scale pockets; eye greyish; a large opecular, deep black ocellus spot in male. The brief discussions of its related species are also provided.

A new brackish goby of Drombus (Teleostei: Gobiidae) from Taiwan with short comments on related gobiid species

The brackish environments of Taiwan were relatively unexplored and therefore houses many cryptic fish species, some of which were still unknown to science till this day. After our repeated estuarine surveys and collections, it was encountered an undescribed species of genus Drombus, that can be clearly separated from its congeners by the following unique combinations of characters: (a) dorsal fin elements VI-I, 10; anal fin elements I, 9; pectoral fin elements modally 17; (b) longitudinal scale rows 32–34; transverse scale rows modally 13; predorsal scale rows 9–10; and (c) specific coloration: body brownish with dark red spots scattered; first dorsal fin dusky with a black blotch. The brief morphological comparisons of the new species with its congeners is also provided herein.

Meristic and morphometrics of tinfoil barb (Barbonymus schwanefeldii) in the Lau Belawan River, Pancur Batu, North Sumatera Province

Abstract Lau Belawan River has several unique fish species, including tinfoil barb (Barbonymuus schwanefeldii). Tinfoil barb is one of the consumption fisheries resources with a fairly high price. The fishing trend along the Lau Belawan River carried out by fishermen also pays little attention to the sustainability of fish population resources. This study aims to determine the morphometrics and meristic of tinfoil barb (Barbonymus schwanefeldii) in Lau Belawan River, Pancur Batu, North Sumatera. This research was conducted from November 2023 to January 2024 for 3 months. Fish were caught using electrofishing units with a voltage of 24 volts. Analysis of morphometric characteristics of tinfoil barb in the Lau Belawan River there is a cluster of 1 type of fish that has the same characteristics consisting of k27, k52, k26, station II consists of k8, k46, k2, k1 and station III consists of k79, k110, k112. Number of Linnea literal scales range of 32-36, 32, 32-38, the transverse body scales range 16-18, 14-16,12-16, frontal scales of the dorsal fin range 15-16, 15,12-16, scales around the caudal trunk 16, number of dorsal fins DIII.8, pelvic fins VI.8, pectoral fins PI.8-10, PI.8, PI.6-12, anal fins AIII.6, and caudal fins 32 and 25-34.

Transverse clues on the kiloparsec-scale structure of the circumgalactic medium as traced by C IV absorption

The kiloparsec-scale kinematics and density structure of the circumgalactic medium (CGM) is still poorly constrained observationally, which poses a problem for understanding the role of the baryon cycle in galaxy evolution. Here we present VLT/MUSE integral-field spectroscopy (R ≈ 1800) of four giant gravitational arcs exhibiting W0 ≳ 0.2 Å C IV absorption at eight intervening redshifts, zabs ≈ 2.0–2.5. We detected C IV absorption in a total of 222 adjacent and seeing-uncorrelated sight lines whose spectra sample beams of (“de-lensed”) linear size ≈1 kpc. Our data show that (1) absorption velocities cluster at all probed transverse scales, Δr⊥ ≈ 0–15 kpc, depending on system; (2) the (transverse) velocity dispersion never exceeds the mean (line-of-sight) absorption spread; and (3) the (transverse) velocity autocorrelation function does not resolve kinematic patterns at the above spatial scales, but its velocity projection, ξarc(Δv), exhibits a similar shape to the known two-point correlation function toward quasars, ξQSO(Δv). An empirical kinematic model suggests that these results are a natural consequence of wide-beam observations of an unresolved clumpy medium. Our model recovers both the underlying velocity dispersion of the clumps (70–170 km s−1) and the mean number of clumps per unit area (2–13 kpc−2). The latter constrains the projected mean inter-clump distance to within ≈0.3–0.8 kpc, which we argue is a measure of clump size for a near-unity covering fraction. The model is also able to predict ξarc(Δv) from ξQSO(Δv), suggesting that the strong systems that shape ξarc(Δv) and the line-of-sight velocity components that define ξQSO(Δv) trace the same kinematic population. Consequently, the clumps must possess an internal density structure that generates both weak and strong components. We discuss how our interpretation is consistent with previous observations using background galaxies and multiple quasars as well as its implications for the connection between the small-scale kinematic structure of the CGM and galactic-scale accretion and feedback processes.

Image reconstruction with the use of fresnel holograms: relationship between the longitudinal and transverse scales of images

Image reconstruction with the use of fresnel holograms: relationship between the longitudinal and transverse scales of images

Perturbative color correlations in double parton scattering

In this paper, we study the contribution of color correlations to Double Parton Scattering (DPS). We show that there is a specific class of Feynman diagrams related to so-called [Formula: see text] processes when the contribution of these color correlations is not Sudakov suppressed with the transverse scales. The effective absence of Sudakov suppression gives hope that although they are small relative to color singlet correlations, they eventually can be observed.

Isolating perturbative QCD splittings in heavy-ion collisions

We define a new strategy to scan jet substructure in heavy-ion collisions. The scope is multifold: (i) test the dominance of vacuum jet dynamics at early times, (ii) capture the transition from coherent to incoherent jet energy loss, and (iii) study elastic scatterings in the medium, which are either hard and perturbative or soft and responsible for jet thermalization. To achieve that, we analyze the angular distribution of the hardest splitting, θhard, above a transverse momentum scale, ktmin, in high-pt jets. Sufficiently high values of ktmin target the regime in which the observable is uniquely determined by vacuumlike splittings and energy loss, leaving the jet substructure unmodified compared to proton-proton collisions. Decreasing ktmin enhances the sensitivity to the relation between energy loss and the intrajet structure and, in particular, to observe signatures of color decoherence at small angles. At wider angles it also becomes sensitive to hard elastic scatterings with the medium and, therefore, the perturbative regime of medium response. Choosing ktmin≈0 leads to order one effects of nonperturbative origin such as hadronization and, potentially, soft scatterings responsible for jet thermalization. We perform a comprehensive analysis of this observable with three state-of-the-art jet-quenching Monte Carlo event generators. Our study paves the way for defining jet observables in heavy-ion collisions dominated by perturbative QCD and thus calculable from first principles. Published by the American Physical Society 2024

Effects of turbulence integral length scales on aerodynamic characteristics and displacement responses of a square prism

This paper investigates the influence of the inflow turbulence integral length scales on the aerodynamic forces on a surface-mounted finite-length square prism and its displacement responses by computational fluid dynamics simulations. Four turbulent inflow conditions with the same mean wind speed and turbulence intensity but different longitudinal and transverse turbulence integral length scales are generated for the simulations. First, the wind pressures and forces on a rigid square prism model and the shear layer characteristics are simulated by large eddy simulations. The simulation results show that the mean characteristics of the wind pressures and shear layers are not sensitive to the turbulence integral length scales. However, the root mean square (RMS) wind pressures on side faces and RMS across-wind forces are increased with the longitudinal turbulence integral length scale, and the mechanism is analyzed by the proper orthogonal decomposition. Second, the displacement responses at the mean wind speed of vortex-induced resonance are computed based on an aeroelastic square prism model by fluid–solid interaction simulations. The RMS displacements of the model are observed to be more sensitive to the transverse turbulence integral length scale rather than the longitudinal turbulence integral length scale. Finally, the influence of the turbulence integral length scales on the Reynolds stresses around the square prism is presented and discussed.

Reconstruction of images using Fresnel holograms: the relationship between the longitudinal and transverse scales of images

The article is devoted to the study of changes in the relationship between the transverse and longitudinal scales of images. The possibility of changing the classical quadratic relationship between the longitudinal and transverse scales of images is considered, while when using traditional imaging methods in classical optics this is impossible due to the homogeneity and isotropy of space. An analysis of image scale transformations for optical schemes of Fresnel holography using spatially incoherent radiation has been carried out. It is shown that recording a Fresnel hologram allows one to change the ratio between the transverse and longitudinal scales of the reconstructed image within a fairly wide range. The results are relevant for use in those areas of science and technology that require the creation of images that reflect real-world objects as accurately as possible without distortion, for example, in the field of medical imaging.

Milliarcsecond localization of the hyperactive repeating FRB 20220912A

ABSTRACT We present very long-baseline interferometry (VLBI) observations of the hyperactive repeating FRB 20220912A using the European VLBI Network (EVN) outside of regular observing sessions (EVN-Lite). We detected 150 bursts from FRB 20220912A over two observing epochs in 2022 October. Combining the burst data allows us to localize FRB 20220912A to a precision of a few milliarcseconds, corresponding to a transverse scale of less than 10 pc at the distance of the source. This precise localization shows that FRB 20220912A lies closer to the centre of its host galaxy than previously found, although still significantly offset from the host galaxy’s nucleus. On arcsecond scales, FRB 20220912A is coincident with a persistent continuum radio source known from archival observations; however, we find no compact persistent emission on milliarcsecond scales. The 5σ upper limit on the presence of such a compact persistent radio source is 120 μJy, corresponding to a luminosity limit of (D/362.4 Mpc)$^2\, 1.8\times 10^{28}$erg s−1 Hz−1. The persistent radio emission is thus likely to be from star formation in the host galaxy. This is in contrast to some other active FRBs, such as FRB 20121102A and FRB 20190520B.

Multi Satellite Observation of a Foreshock Bubble Causing an Extreme Magnetopause Expansion

AbstractThe interaction of a solar wind discontinuity with the backstreaming particles of the Earth’s ion foreshock can generate hot, tenuous plasma transients such as foreshock bubbles (FB) and hot flow anomalies (HFA). These transients are known to have strong effects on the magnetosphere, distorting the magnetopause (MP), either locally during HFAs or globally during FBs. However, previous studies on the global impact of FBs have not been able to determine whether the response stems directly from the transverse scale size of the phenomenon or its fast motion over the magnetosphere. Here we present the observation of an FB and its impact on the magnetosphere from different spacecraft scattered over the dayside magnetosphere. We are able to constrain the size of the transverse scale of an FB from direct observations to be about 10 RE. We go on to discuss how the magnetosphere responds to this transient, which seems to have a similar scale across the dayside.

Bridging the gap: A new species of arboreal Abronia (Squamata: Anguidae) from the Northern Highlands of Chiapas, Mexico.

The mountain forests of Middle America are renowned for their endemic biodiversity, and arboreal alligator lizards (genus Abronia) are high-profile vertebrates endemic to this region. In this work, we describe a new species of arboreal Abronia that is known only from the type locality in the Northern Highlands of Chiapas, Mexico. The new species is diagnosed from all other members of the genus Abronia by the following combination of characters: lack of protuberant or spine-like supra-auricular scales, lack of protuberant or casque-like posterolateral head scales, dorsum of head pale yellow with distinct dark markings, 35-39 transverse dorsal scale rows, lateralmost row of ventral scales enlarged relative to adjacent medial row, and dorsum brown with darker crossbands that are sometimes reduced to rows of spots. We provisionally include the new species in the subgenus Lissabronia based on genomic and morphological evidence, but our results also suggest a close relationship to the subgenus Abaculabronia. The new species is geographically separated from the nearest Lissabronia and Abaculabronia species by the lowland Central Depression of Chiapas. Ongoing habitat loss and other factors imperil the new species, leading us to propose its listing under multiple threatened species frameworks. Because the Northern Highlands have poor coverage of protected areas, we briefly comment on the potential of this new species for stimulating conservation in the region.

Probing magneto-ionic microstructure towards the Vela pulsar using a prototype SKA-Low station

Abstract The Vela pulsar (J0835 $-$ 4510) is known to exhibit variations in Faraday rotation and dispersion on multi-decade timescales due to the changing sightline through the surrounding Vela supernova remnant and the Gum Nebula. Until now, variations in Faraday rotation towards Vela have not been studied on timescales less than around a decade. We present the results of a high-cadence observing campaign carried out with the Aperture Array Verification System 2 (AAVS2), a prototype SKA-Low station, which received a significant bandwidth upgrade in 2022. We collected observations of the Vela pulsar and PSR J0630 $-$ 2834 (a nearby pulsar located outside the Gum Nebula), spanning $\sim$ 1 and $\sim$ 0.3 yr, respectively, and searched for linear trends in the rotation measure (RM) as a function of time. We do not detect any significant trends on this timescale ( $\sim$ months) for either pulsar, but the constraints could be greatly improved with more accurate ionospheric models. For the Vela pulsar, the combination of our data and historical data from the published literature have enabled us to model long-term correlated trends in RM and dispersion measure (DM) over the past two decades. We detect a change in DM of $\sim$ 0.3 $\mathrm{cm}^{-3}\,\mathrm{pc}$ which corresponds to a change in electron density of $\sim$ $10^5\,\mathrm{cm}^{-3}$ on a transverse length scale of $\sim$ 1–2 au. The apparent magnetic field strength in the time-varying region changes from $240^{+30}_{-20}\,\mu\mathrm{G}$ to $-6.2^{+0.7}_{-0.9}\,\mu\mathrm{G}$ over the time span of the dataset. As well as providing an important validation of polarimetry, this work highlights the pulsar monitoring capabilities of SKA-Low stations, and the niche science opportunities they offer for high-precision polarimetry and probing the microstructure of the magneto-ionic interstellar medium.

Two new species of freshwater goby (Teleostei, Gobiidae) from the Upper Youshui River, Chongqing, China.

Two previously unknown species of Rhinogobius have been discovered in the streams of the Upper Youshui River, within the Yuan River Basin, Xiushan County, Chongqing, China. These new species are named as Rhinogobiussudoccidentalis and Rhinogobiuslithopolychroma. Phylogenetic analysis based on mitochondrial genomes revealed that R.sudoccidentalis is genetically closest to R.reticulatus, while R.lithopolychroma shares the greatest genetic similarity with R.leavelli. Morphological distinctions allow for the clear differentiation of these species. Rhinogobiussudoccidentalis sp. nov. is characterized by having VI-VII rays in the first dorsal fin and I, 8-9 rays in the second dorsal fin. The longitudinal scale series typically consists of 22-24 scales, while the transverse scale series comprises 7-8 scales. Notably, the predorsal scale series is absent and the total vertebrae count is 12+17=29. Rhinogobiuslithopolychroma sp. nov. can be distinguished from other species by the presence of 13-15 rays on the pectoral fin. Its longitudinal scale series ranges from 30 to 33 scales, with no scales in the predorsal area. The total vertebral count is 30, with 12 precaudal and 18 caudal vertebrae. The head and body of this species are light gray with irregular orange markings on the cheeks and opercle. Through morphological and molecular analyses, it has been confirmed that R.lithopolychroma and R.sudoccidentalis represent novel species within the Rhinogobius genus.

Role of chirped factor on the focusing and imaging properties of the autofocusing beam

The focusing and imaging properties of the beam have attracted considerable attention recently. In this work, we generated an autofocusing beam termed a chirped autofocusing beam (CAFB) by using the phase of multiple chirped two-dimensional Airy beams, which has autofocusing and imaging properties. Through simulation analysis and experimental verification, it was found that the CAFB is endowed with multiple degrees of freedom to control the focusing properties of the CAFB. Specially, in the range of negative and weak chirp, the focal length of the CAFB increases with decreasing chirped factor. Moreover, the imaging property of the CAFB can be controlled by a chirp factor, the transverse displacement of the CAFB, and the transverse scale factor of the CAFB. The larger the transverse displacement and transverse scale factor of the beam, the better the image quality. Due to these properties, the CAFB may broaden the potential applications in optical microscopy imaging.

Comprehensive analysis of the influence of magnetic field gradients on single-beam SERF atomic magnetometer

Magnetic field gradients interfere with the coherence of the atomic ensemble and degrade the performance of the spin-exchange relaxation-free (SERF) atomic magnetometer. In this paper, the influence of magnetic field gradients is incorporated into the response model of single-beam atomic magnetometer, and the theoretical models of transverse relaxation rate, spin polarization and scale factor are established. Based on this model, we find that magnetic field gradients in different directions can cause varying degrees of degradation in the performance parameters of the magnetometer. The magnetic linewidths under different light power and magnetic field gradients are measured using the designed dedicated magnetic field gradients coils, and the spin polarization and magnetic field gradients relaxation rate are obtained through fitting. An unevenness and deviation of the curve are also observed in the experiments, indicating the presence of the magnetic field gradient of approximately 2 nT/cm in the magnetic shields. Furthermore, in a magnetic field gradient environment of 20 nT/cm, the mean of the long-term sensitivity decreased by 3.5 times and the standard deviation increased by 11 times. It shows that the magnetic field gradients will not only affect the signal-to-noise ratio, but also make the magnetometer more vulnerable to external interference when working. The sensitivity and stability of magnetometer will be greatly reduced. The research in this article provides a theoretical and experimental basis for eliminating the influence of magnetic field gradients and improving the accuracy of magnetic field measurements.

Robust cosmological inference from non-linear scales with k-th nearest neighbour statistics

ABSTRACT We present the methodology for deriving accurate and reliable cosmological constraints from non-linear scales ($\lt 50\, h^{-1}$ Mpc) with k-th nearest neighbour (kNN) statistics. We detail our methods for choosing robust minimum scale cuts and validating galaxy–halo connection models. Using cross-validation, we identify the galaxy–halo model that ensures both good fits and unbiased predictions across diverse summary statistics. We demonstrate that we can model kNNs effectively down to transverse scales of $r_{\rm p}\sim 3\, h^{-1}$ Mpc and achieve precise and unbiased constraints on the matter density and clustering amplitude, leading to a 2 per cent constraint on σ8. Our simulation-based model pipeline is resilient to varied model systematics, spanning simulation codes, halo finding, and cosmology priors. We demonstrate the effectiveness of this approach through an application to the Beyond-2p mock challenge. We propose further explorations to test more complex galaxy–halo connection models and tackle potential observational systematics.

Radiofrequency ice dielectric measurements at Summit Station, Greenland

Abstract We recently reported on the radio-frequency attenuation length of cold polar ice at Summit Station, Greenland, based on bi-static radar measurements of radio-frequency bedrock echo strengths taken during the summer of 2021. Those data also allow studies of (a) the relative contributions of coherent (such as discrete internal conducting layers with sub-centimeter transverse scale) vs incoherent (e.g. bulk volumetric) scattering, (b) the magnitude of internal layer reflection coefficients, (c) limits on signal propagation velocity asymmetries (‘birefringence’) and (d) limits on signal dispersion in-ice over a bandwidth of ~100 MHz. We find that (1) attenuation lengths approach 1 km in our band, (2) after averaging 10 000 echo triggers, reflected signals observable over the thermal floor (to depths of ~1500 m) are consistent with being entirely coherent, (3) internal layer reflectivities are ≈–60 $\to$ –70 dB, (4) birefringent effects for vertically propagating signals are smaller by an order of magnitude relative to South Pole and (5) within our experimental limits, glacial ice is non-dispersive over the frequency band relevant for neutrino detection experiments.

Excellent ultraviolet optical limiting properties of Se nanosheets

Selenium (Se) is located in the fourth period of the periodic table in group VIA (element 34). In this experiment, three different solvents (isopropyl alcohol, N-methyl-2-pyrrolidone, and ethanol) were used to prepare the two-dimensional Se nanosheets, which were manufactured by the liquid phase exfoliation method with a thickness of 3.35–4.64 nm and a transverse scale of several hundred nanometers. The nonlinear absorption properties at 355, 532, and 1064 nm were studied using the open aperture Z-scan technique. Final results showed that Se nanosheets exhibited optical limiting (OL) effect in all three wavebands and three solvents, and had large two-photon absorption coefficients, especially in ultraviolet (UV) waveband. Which proved that Se nanosheets had great potential application as excellent OL materials in UV waveband. Our research broadens the path for the semiconductor field of Se, inspires the application of Se in nonlinear optics field.

RGBT tracking based on prior least absolute shrinkage and selection operator and quality aware fusion of deep and handcrafted features

Object tracking has always been one of the most challenging topics in machine vision. In recent years, trackers have used RGB-T datasets to overcome the limitations of single-modality data. This paper introduces a Prior Least Absolute Shrinkage and Selection Operator (PLASSO)-based cost function optimized by the Alternating Direction Method of Multipliers (ADMM) for a Discriminative Correlation Filter (DCF)-based tracker. Detailed closed-form solutions for these optimization problems are also given in this paper. The proposed PLASSO-based approach adaptively determines the scale, parameters, and features of the PLASSO-ADSPF tracker. PLASSO- ADSPF first finds the response map in the Fourier domain for the input images and then uses an efficient adaptive function to fuse the results. Based on the response maps, the proposed tracker adaptively and consciously extracts features (handcraft and Deep Features (DF)) to improve the speed of the tracking algorithm. PLASSO-ADSPF extracts DF from the convolution layer output of a modified pre-trained deep network via SoftMax Tsallis Entropy (TsEn) as a proposed cost function in the last layer. Also, a graph is proposed to determine longitudinal and transverse scales independently and accurately. Moreover, a new bounding box regression is proposed based on PLASSO and Cholesky factorization to refine the target box. Extensive experiments have been performed for the PLASSO-ADSPF tracker on five popular datasets. The results show the superiority of the proposed approach compared to the state-of-the-art trackers. Our code is available at PLASSO-ADSPF-tracker.