Sharp Variations Research Articles

Metabolism Variations in the Bivalve Mollusk <i>Anadara kagoshimensis</i> Tokunaga, 1906 (Bivalvia: Arcidae) under Upwelling Conditions in the Black Sea (Experimental Data)

Studies of the energy metabolism in a bivalve mollusk, the ark clam Anadara kagoshimensis (Tokunaga, 1906), were carried out for the first time under experimental conditions simulating dynamic variations in the seawater characteristics at the stages of development and end of upwelling event in the Black Sea. It was shown that the level of energy metabolism of A. kagoshimensis, while being in the zone of upwelling formation, reduced, on average, by 5% per degree of temperature decrease. During the upwelling relaxation phase (14→26°C), the restoration of the respiration intensity parameters of the clam was slower than expected, with a temperature coefficient Q10 = 1.31. The acidification of the seawater by 1.0 (up to рН 7.2), combined with a temperature decrease (26→20°C), aggravated the negative effect by 25–45%. It has been found that the clam A. kagoshimensis reduces energy expenditure by approximately 60% under upwelling conditions (cold stress and acidification). Consequences of the negative effect of a sharp temperature variation lead to a delay in the metabolism recovery to normal values.

Hematological Features of Codfishes (Gadidae) from the Northwest Pacific

Hematological parameters of the peripheral blood of the walleye pollock Gadus chalcogrammus Pallas, 1814, saffron cod Eleginus gracilis Tilesius, 1810, and Pacific cod Gadus macrocephalus Tilesius, 1810 from the Sea of Okhotsk were studied. An analysis of the leukogram of the studied species revealed a large portion of segmented neutrophils and myelocytes in walleye pollock, which indicates a significant potential of the cellular factor of its innate immunity and a greater activity of corticosteroid hormones. The most active erythropoiesis observed in G. chalcogrammus is probably related to substantial vertical migrations, specific for the species, associated with sharp pressure variations and the necessity to provide the body with oxygen. The high level of leukopoiesis revealed in saffron cod is assumed to be caused by ecological adaptations of the species to inhabit both fresh and sea water.

Refining Heterogeneities near the Core–Mantle Boundary Beneath East Pacific Regions: Enhanced Differential Travel-Time Analysis Using USArray

Recent advancements in seismic data analysis have enhanced our grasp of the seismic heterogeneities near the core–mantle boundary (CMB). Through seismic tomography, persistent lower-mantle structures like the large low shear velocity provinces (LLSVPs) beneath the Pacific and South Africa have been identified. However, variations in the finer-scale features across different models raise questions about their origins. This study utilizes differential travel-time measurements from the USArray, operational across the contiguous United States from 2007 to 2014, to examine the impact of upper-mantle heterogeneities on tomographic models. By averaging the P-wave travel times and calibrating them with diffracted P-waves at the same stations, we mitigate the effects of shallow heterogeneities. The findings confirm that this method accurately maps the seismic anomalies beneath the USArray, consistent with other North American studies. Calibrated Pdiff travel-time data indicate significant anomalies in the mid-Pacific and Bering Sea and lesser anomalies in the northern Pacific, aligning with the global tomographic images. Moreover, the study highlights sharp travel-time variations over short distances, such as those across the northern boundary of the mid-Pacific anomaly, suggesting a chemically heterogeneous Pacific LLSVP.

A many-body quantum model is proposed as the mechanism responsible for accelerating rates of heat uptake by oceans as anthropogenic heat inputs rise

Abstract A recent many-body quantum approach to thermal radiation (Smith GB, et al 2022 J. Phys. Commun. 6, 065004) reveals that the energy capacitance of heated water is about twice its heat capacitance, due to energy stored as local hybrid pairs of photons coupled resonantly to local matter excitations, with pair density weighted by mass density. Energy exchange between photons and localised dipole excitations inside water at steady temperature T, occurs at sites where a hybridisation potential within the Hamiltonian couples local oscillation modes to ‘free’ photon modes. Photon modes in both directions are phase retarded at exit sides of a hybrid site. Optically sharp variations with frequency in the index of refraction n(f) and photon density of states follow. Exit spectral intensities at equilibrium temperature T carry quantum information on the energy density of matter excitations coupled to photons, while occupied hybrid sites are the source of all ‘free’ photons and internal spectral intensities. The matter excitations coupled locally to photons are distinct from those that define specific heat, but in water both arise from molecular oscillations. The energy capacitance CEX(T) of hybrid pairs depends on mass density and is independent of the heat capacitance CHT(T), which sets temperature T. CEX(T) is sensitive to T and doubles as a capacitance of energy and of ‘quantum information’. Expressions for CEX(T) are derived from first principles and applied to water. The density of occupied hybrids is amplified near surfaces by photons reflected off the surface, which create new hybrid pairs, but not extra heat. Energy capacitance CEX(T)+CHT(T) sets dT(t)/dt prior to a new equilibrium state emerging, after input heating rate dQ/dt is switched. Rising atmospheric intensities then raise T, dQ/dt, CEX(T) and CHT(T). The times available to cool overnight are fixed, so that a rising capacitance, adds to energy stored at an accelerating rate.

Probabilistic modeling of multivariate extreme non-Gaussian wind loads and its applications in envelope engineering

Probabilistic modeling for non-Gaussian wind load fields under extreme winds is crucial to the quantitative risk and reliability analysis of envelope structures. Based on the multi-point synchronous wind load data during typhoons, a probabilistic model is proposed to characterize multivariate non-Gaussian wind loads to improve the accuracy of the risk analysis considering data dimension reduction. In the proposed model, the Pareto distribution function is utilized to fit the marginal distribution, and the copula function is employed to construct the dependent structure of wind loads from different locations. In the marginal fitted results, the extreme wind load value in the edge region is about 0.10–0.15 higher than those from inner measurement points at quantile p = 95 %. In addition, the variation gradient from the different variable directions is approximately equal, and a sharp variation occurs at the point (0.10, 0.10) for bivariate joint distributions. Engineering applications given in this article are composed of three parts: calculating regional exceeding probability, estimating wind load vector under a specific regional exceeding probability, and determining the location of joint extreme wind loads using the joint gradient value. Finally, risk analysis of existing roof coverings is carried out, the edge corner region is weaker, and two engineering recommendations are given. For determining the regional design wind load, a comprehensive calculation framework considering the temporal dependence of different locations is established, and the reduction rates are in the range (5 %, 25 %).

Smart detection of subsurface anomalies: Concept, validation and applications

Naturally formed and engineering-induced subsurface anomalies (e.g., cavities and sinkholes) jeopardize infrastructure safety and hinder urban sustainability. Here we report a smart sensing method to detect subsurface anomalies based on the physical characteristics extracted from the effective signals scattered and reflected directly from these anomalies. Potential anomalies at submeter scales can be interpreted based on a sharp variation of anomaly score relative to the background anomaly score, showing the advantage of overcoming subjective uncertainty and biases involved in the traditional geophysical methods. We find that the use of scattered and reflected waves in an intermediate frequency range is well-suited for sensing deep subsurface infrastructure at high resolutions required for civil structures. We also demonstrate that a fast and reliable detection of subsurface anomalies relies solely on the physical characteristics of seismic data in two field cases, promoting geologic hazard forecast and decision-making effectiveness.

Synthesis and luminescent properties of five-six-membered bis(metallacyclic) platinum(II) complexes bearing polypyridine alkynes

A series of five-six-membered bis(metallacyclic) Pt(II) complexes bearing a 2,2′-bipyridine (BPY) or 2,2′:6′,2"-terpyridine (TPY) ethynyl ligand were synthesized and characterized. The structures of N^C*N-coordinated Pt(II) complexes (−)-1 and (−)-5 were confirmed by single crystal X-ray diffraction, displaying a slightly distorted square-planar coordination environment around the Pt(II) centers. Compared to N^N*C-coordinated Pt(II) derivatives ((−)-2, (−)-4 and (−)-6), N^C*N-coordinated complexes ((−)-1, (−)-3 and (−)-5) demonstrate a more significant AIE property with a sharp luminescence variation in response to water content. In addition, due to the existence of the pendent BPY or TPY unit, N^C*N-coordinated Pt(II) complexes show a luminescence response to Zn2+ ions. Cytotoxicity and cell imaging of luminescent five-six-membered bis(metallacyclic) Pt(II) complexes with polypyridine alkynes have been evaluated.

Buckling optimization of Double-Double (DD) laminates with gradual thickness tapering

Double-double (DD) laminates are promising replacements for conventional Quad laminates in aerospace applications because of their inherent design simplicity and, more importantly, the ease of tapering. However, the thickness thinning due to tapering will significantly increase the risk of buckling failure. In this paper, we proposed an implicit global & local model for thickness tapering optimization of DD laminates to maximize buckling resistance under the given weight constraint or weight reduction under buckling constraints. Firstly, a global model is established for buckling load calculation, with material properties calculated from homogenization of local laminates using the classical laminate theory. Then, nodal repeats of a four-plies DD sub-laminate are chosen as design variables to interpolate the tapered thickness profile. Sensitivities of structural responses are calculated semi-analytically to achieve efficient gradient-based optimization. Tapering spacing constraints between adjacent thicknesses are introduced to mitigate the potential delamination due to the stress concentrations caused by sharp thickness variation at the cost of a reduced optimization effect. Finally, typical numerical examples show that DD laminates with optimal gradual thickness tapering can remarkably increase the structural buckling resistance or the weight reduction.

Gelatin-kappa-carrageenan-based edible film incorporated with ethanol extracts from Premna microphylla Turcz leaves for preservation of sailfish fillets

This study proposes to develop edible films (EF) by modification of gelatin/kappa (κ)-carrageenan (KCAR) as a base formulation while incorporating the Premna microphylla Turcz leaf (PMTL) extracts. PMTLs were extracted via distilled water or 95% ethanol (1:20 ratio, w/v) to investigate the content of bioactive substances and evaluate their antioxidant and antimicrobial capacities. The PMTL ethanol extract (PEE) showed satisfactory antimicrobial and antioxidant performance compared to the water extract (PWE). Therefore, different ratios of PEE (0, 5, 10, and 15%) were incorporated into the basic formulation of EF supplemented with the plasticizing agent glycerol (0.5 and 1%) to prolong the shelf-life of sailfish fillets (SF). Incorporating PEE into EF formulations may change the color from transparent to yellow-green, which improves EF's moisture content, solubility, swelling degree, and hydrophilicity. PEE's total phenolic content (TPC) and total flavonoid content (TFC) provided EF with antioxidant capacity, causing EF with predictable mitigation of sharp variation in pH, total plate count, thiobarbituric acid reactive substances (TBARS) value, and histamine content during the storage period of SF (12 days at 4 °C). Altogether, this study indicated that EFs manufactured by PEE would be potential candidates for application in food preservation to improve food safety.

Local spline refinement driven by fault jump estimates for scattered data approximation

We present new fault jump estimates to guide local refinement in surface approximation schemes with adaptive spline constructions. The proposed approach is based on the idea that, since discontinuities in the data should naturally correspond to sharp variations in the reconstructed surface, the location and size of jumps detected in the input point cloud should drive the mesh refinement algorithm. To exploit the possibility of inserting local meshlines in one or the other coordinate direction, as suggested by the jump estimates, we propose a quasi-interpolation (QI) scheme based on locally refined B-splines (LR B-splines). Particular attention is devoted to the construction of the local operator of the LR B-spline QI scheme, which properly adapts the spline approximation according to the nature and density of the scattered data configuration. A selection of numerical examples outlines the performance of the method on synthetic and real datasets characterized by different geographical features.

The division of parental leave: Empirical evidence and policy design

We study several key aspects of the design of parental leave systems. First, we estimate parents’ willingness to pay for parental leave using Danish administrative data on the division of leave from almost 190,000 births combined with sharp variation in economic incentives created by the parental leave benefit system. We find evidence of both strong behavioral responses with significant bunching at kink points and a willingness to pay for a gender-traditional allocation of leave, where fathers take little or no leave. Second, we provide a menu of counterfactual policy simulations showing substantial interaction effects between earmarked leave, replacement rates and the duration of leave benefits. Relevant for the implementation of a recent EU directive, a higher replacement rate significantly increases the behavioral response of fathers to earmarked leave. Finally, we discuss the welfare effects of different policies aimed at increasing the parental leave of fathers.

Lightweight pyramid attention residual network for intelligent fault diagnosis of machine under sharp speed variation

Deep learning based diagnostic methods have obtained great success in intelligent fault diagnosis of machines. However, most of the existing methods are developed for fault diagnosis task under stable working conditions, and cannot handle the data generated under sharp speed variation favorably. Besides, the large model parameters and high computing costs of these methods fail to meet the requirement of small memory and fast-precise prediction in practical applications. To address these challenges, a lightweight pyramid attention residual network (PARNet) is proposed in this paper. First, an efficient pyramid squeeze convolution module is proposed to capture multi-scale information from raw signals. Then, a soft squeeze-and-excitation attention is designed to establish long-range channel dependency, and fuse features of different scales. Based on the above improvements, a pyramid attention residual block is proposed as basic feature learning unit, and a concise CNN-based model PARNet is built using PAR block. Extensive experiments in two case studies are conducted to validate the effectiveness and adaptability of PARNet under different speed variation conditions. The test results demonstrate the superiority of the proposed method for machine fault diagnosis and reliability assessment in terms of recognition accuracy and model parameter complexity, compared with other advanced diagnostic methods.

Online discrimination-correction subnet for background suppression and dynamic template updating in Siamese visual tracking

The offline Siamese tracking methods have recently attracted much attention due to their impressive performance on speed and accuracy. However, they ignore the target and background information during tracking, thus lacking sufficient discrimination ability to handle complex background interference, and cannot robustly adapt to sharp appearance variations in challenging situations, such as scale variation, rotation, occlusion, and background clutter. To address the drawbacks above, we propose an online discrimination-correction subnet, which discriminates and corrects the tracking results obtained by the Siamese tracker through online learning, and further guides the template update. Firstly, a feature refinement module is designed to enhance the discriminative ability of features, which compresses and combines target features based on the importance of feature channels to obtain target-specific features. On this basis, an online discriminator module is proposed to learn the decision boundary between target and background through samples collected online to suppress background interference. In addition, a sample equilibrium strategy is proposed to alleviate the imbalance in the distribution of positive and negative samples during online training. Finally, to handle sharp target appearance variations, a robust template updating strategy is proposed to screen high-quality historical samples to generate dynamic templates. To evaluate the generalization ability and effectiveness of our method, we apply it to four classical Siamese trackers, namely SiamFC, SiamRPN++, SiamCAR, and TransT. Extensive experiments on seven challenging benchmarks demonstrate that our method significantly improves the baseline methods and achieves outstanding performance compared with state-of-the-art trackers.

Artificial excitation and propagation of ultra-low frequency signals in the polar ionosphere

This paper has established a relatively comprehensive model for ultra-low frequency (ULF) current induced by thermal pressure gradients and its propagation. In the ULF current excitation model, we decomposed the current into a constant term unaffected by altitude and a product with a function significantly influenced by altitude. Combining this with the EISCAT background, we determined that for modulation frequencies below 5 Hz, the optimal height for ULF current excitation corresponds to the critical frequency height. We calculated the ionospheric currents at heating altitudes of 332 km for modulation frequencies of 5 Hz; the corresponding maximum currents were 1.03 × 10−10 A·m−2. By incorporating the current into the ULF waves propagation model based on magnetoionic theory, we found that the electromagnetic field energy is mainly concentrated in the horizontal direction, indicating that the energy primarily propagates outward through magnetosonic waves. The dominant components are the electric field component Ey and the magnetic field component Bz, whose maximum values reached 1.1 μV·m−1 and 1.5 pT. Unfortunately, magnetosonic waves cannot propagate downward due to the sharp variation in the real part of the refractive index between 200 and 300 km. However, the shear Alfvén waves component By can propagate downward, and there is still an intensity of approximately 0.1 pT at the bottom of the ionosphere, which is because the refractive index of shear Alfvén waves is most uniform in the parallel magnetic field direction, allowing By to propagate parallel to the magnetic field effectively.

Magnetic relaxation between ferromagnetic and helix spin configurations in holmium films

Multiple noncollinear spin structures and transitions between them initiated by field and temperature have attracted attention due to the extraordinary coexistence of complicated spin phases in Ho. We explore the magnetic relaxation dynamics within thin films undergoing transitions between ferromagnetic (FM) and helix states. When measuring susceptibility in a relatively high frequency range (∼100–1500 Hz) and magnetic viscosity at lower frequency (∼0.01 Hz), we focus on 400 nm thick Ho film. Notably, sharp variations in the real and imaginary components of magnetic susceptibility are discerned during the FM – Helix transition, occurring at temperatures between 15 and 30 K. Hysteresis effects in the magnetic susceptibility components are identified during cyclic variations in the external field, indicating a relatively rapid process with a timescale of approximately 10 ms accompanying the FM – Helix transition. The slow relaxation process is also found to exhibit sensitivity to this transition. Furthermore, the field dependence of magnetic viscosity displays a marked decline at the FM – Helix transition. The research methodologies proposed for the investigation of relaxation processes in materials with multiphase spin structures are deemed universally applicable and offer insights into transitions between spin states in materials manifesting non collinear spin structures.

Spin–wave dynamics in perpendicularly magnetized antidot multilayers

Using all-optical time-resolved magneto-optical Kerr effect measurements we demonstrate an efficient modulation of the spin–wave (SW) dynamics via the bias magnetic field orientation around nanoscale diamond shaped antidots that are arranged on a square lattice within a [Co(0.75 nm)/Pd(0.9 nm)]8 multilayer with perpendicular magnetic anisotropy (PMA). Micromagnetic modeling of the experimental results reveals that the SW modes in the lower frequency regime are related to narrow shell regions around the antidots, where in-plane (IP) domain structures are formed due to the reduced PMA, caused by Ga+ ion irradiation during the focused ion beam milling process of antidot fabrication. The IP direction of the shell magnetization undergoes a striking change with magnetic field orientation, leading to the sharp variation of the edge localized (shell) SW modes. Nevertheless, the coupling between such edge localized and bulk SWs for different orientations of bias field in PMA systems gives rise to interesting Physics and attests to new prospects for developing energy efficient and hybrid-system-based next-generation nanoscale magnonic devices.

Plasmon-mediated dynamics and lasing of nanoemitters enhanced by dispersing nanorings.

We investigate the plasmon-mediated nonlinear dynamics and the optics of a laser emission of random nanoemitters (NEs) embedded in a two-dimensional (2D) lattice of conducting nanorings (NRs) enhanced by plasmon-polariton (PP) excitations. The interaction of quantum NEs with the PP field in the NRs perturbs the dynamics of the electronic populations in NEs, leading to a significant dependence of laser generation (dynamics) on the plasma frequency ωp of PP. This results in a strong coupling of NE field emission with the PP field and sharp variations of the average current in the NR lattice. The phase transition in the system was found when the macroscopic structures of PP fields are excited simultaneously in different regions of the system if ωp (control parameter) reaches critical value ωc. We have established the analytical dependence of the PP current I = I(ωp/ωc) on the plasma frequency, which is in excellent agreement with the results of numerical simulations. This effect may allow the design of new types of PP active devices with the use of conducting NRs in modern nanoelectronics.

Distribution of active ingredients and quality control of Forsythia suspensa with AP-MALDI mass spectrometry imaging.

The fruits of Forsythia suspensa (F. suspensa) have been used as a traditional Chinese medicine for 2000 years. Currently, the quality control of F. suspensa strictly follows the instructions of Chinese Pharmacopeia, which mainly controls the content of forsythoside A, phillyrin, and volatile oil. In this study, air pressure MALDI mass spectrometry imaging (AP-MALDI MSI) was used to evaluate the quality of F. suspensa fruits and the distribution of dozens of active ingredients. The variation of active ingredients was measured for more than 30 batches of samples, regarding harvest time, cultivated environment, shelf-life, and habitat. Fifty-three active ingredients could be detected in F. suspensa fruits with AP-MALDI MSI. Seven active ingredients were upregulated, four ingredients downregulated, and 15 ingredients did not change in ripe fruits. A sharp variation of active ingredients in late September was observed for the Caochuan fruits harvested in 2019, which is closely related to the appearance of the ginger color of the pericarp under the microscope observation. The microscope observation is a reliable way to classify ripe and green fruits instead of outlook. Just considering forsythoside A and phillyrin, it is found that wild fruits are better than cultivated fruits, but cultivated fruits have high contents of other ingredients. The shelf-life of F. suspensa fruits is proposed to be 3 years, considering the 26 ingredients investigated. It was found that Luoning wild fruits are better than those from Caochuan with a new evaluation method. Mass spectrometry imaging is an easy, objective, and effective method to evaluate the quality of F. suspensa fruits.

Buoyancy glitches in pulsating stars revisited

Sharp structural variations induce specific signatures on stellar pulsations that can be studied to infer localised information on the stratification of the star. This information is key to improve our understanding of the physical processes that lead to the structural variations and how to model them. Here we revisit and extend the analysis of the signature of different types of buoyancy glitches in gravity-mode and mixed-mode pulsators presented in earlier works, including glitches with step-like, Gaussian-like, and Dirac-δ-like shapes. In particular, we provide analytical expressions for the perturbations to the periods and show that these can be reliably used in place of the expressions provided for the period spacings, with the advantage that the use of the new expressions does not require modes with consecutive radial orders to be observed. Based on a comparison with two limit cases and on simulated data, we further tested the accuracy of the expression for the Gaussian-like glitch signature whose derivation in an earlier work involved a significant approximation. We find that the least reliable glitch parameter inferred from fitting that expression is the amplitude, which can be up to a factor of two larger than the true amplitude, reaching this limit when the glitch is small. We further discuss the impact on the glitch signature of considering a glitch in the inner and outer half of the g-mode cavity, emphasising the break of symmetry that takes place in the case of mixed-mode pulsators.

Mapping Glacier Structure in Inaccessible Areas From Turning Seismic Sources Into a Dense Seismic Array

AbstractUnderstanding glaciers structural heterogeneity is crucial for assessing their fate. Yet, places where structure changes are strong, such as crevasses fields, are often inaccessible for direct instrumentation. To overcome this limitation, we introduce an innovative technique that transforms seismic sources, here generated by crevasses, into virtual receivers using source‐to‐receiver spatial reciprocity. We demonstrate that phase interference patterns between well‐localized seismic sources can be leveraged to retrieve phase velocity maps using Seismic Michelson Interferometry. The obtained phase velocity exhibits sensitivity to changes in glacier structure, offering insights into the origins of mechanical property changes, with spatial resolution surpassing traditional methods by a factor of five. In particular, we observe sharp variations in phase velocity related to strongly damaged subsurface areas indicating a complex 3‐D medium. Applying this method more systematically and in other contexts will enhance our understanding of the structure of glaciers and other seismogenic environments.