Polar Model Research Articles

The Weakening of the Stratospheric Polar Vortex and the Subsequent Surface Impacts as Consequences to Arctic Sea Ice Loss

Abstract This study investigates the stratospheric response to Arctic sea ice loss and subsequent near-surface impacts by analyzing 200-member coupled experiments using the Whole Atmosphere Community Climate Model version 6 (WACCM6) with preindustrial, present-day, and future sea ice conditions specified following the protocol of the Polar Amplification Model Intercomparison Project. The stratospheric polar vortex weakens significantly in response to the prescribed sea ice loss, with a larger response to greater ice loss (i.e., future minus preindustrial) than to smaller ice loss (i.e., future minus present-day). Following the weakening of the stratospheric circulation in early boreal winter, the coupled stratosphere–troposphere response to ice loss strengthens in late winter and early spring, projecting onto a negative North Atlantic Oscillation–like pattern in the lower troposphere. To investigate whether the stratospheric response to sea ice loss and subsequent surface impacts depend on the background oceanic state, ensemble members are initialized by a combination of varying phases of Atlantic multidecadal variability (AMV) and interdecadal Pacific variability (IPV). Different AMV and IPV states combined, indeed, can modulate the stratosphere–troposphere responses to sea ice loss, particularly in the North Atlantic sector. Similar experiments with another climate model show that, although strong sea ice forcing also leads to tighter stratosphere–troposphere coupling than weak sea ice forcing, the timing of the response differs from that in WACCM6. Our findings suggest that Arctic sea ice loss can affect the stratospheric circulation and subsequent tropospheric variability on seasonal time scales, but modulation by the background oceanic state and model dependence need to be taken into account. Significance Statement This study uses new-generation climate models to better understand the impacts of Arctic sea ice loss on the surface climate in the midlatitudes, including North America, Europe, and Siberia. We focus on the stratosphere–troposphere pathway, which involves the weakening of stratospheric winds and its downward coupling into the troposphere. Our results show that Arctic sea ice loss can affect the surface climate in the midlatitudes via the stratosphere–troposphere pathway, and highlight the modulations from background mean oceanic states as well as model dependence.

PPG-based Continuous BP Waveform Estimation Using Polarized Attention-guided Conditional Adversarial Learning Model.

The blood pressure (BP) waveform is a vital source of physiological and pathological information concerning the cardiovascular system. This study proposes a novel attention-guided conditional generative adversarial network (cGAN), named PPG2BP-cGAN, to estimate BP waveforms based on photoplethysmography (PPG) signals. The proposed model comprises a generator and a discriminator. Specifically, the UNet3+-based generator integrates a full-scale skip connection structure with a modified polarized self-attention module based on a spatial-temporal attention mechanism. Additionally, its discriminator comprises PatchGAN, which augments the discriminative power of the generated BP waveform by increasing the perceptual field through fully convolutional layers. We demonstrate the superior BP waveform prediction performance of our proposed method compared to state-of-the-art (SOTA) techniques on two independent datasets. Our approach first pre-trained on a dataset containing 683 subjects and then tested on a public dataset. Experimental results from the Multi-parameter Intelligent Monitoring in Intensive Care dataset show that the proposed method achieves a root mean square error of 3.54, mean absolute error of 2.86, and Pearson coefficient of 0.99 for BP waveform estimation. Furthermore, the estimation errors (mean error ± standard deviation error) for systolic BP and diastolic BP are 0.72 ± 4.34 mmHg and 0.41 ± 2.48 mmHg, respectively, meeting the American Association for the Advancement of Medical Instrumentation standard. Our approach exhibits significant superiority over SOTA techniques on independent datasets, thus highlighting its potential for future applications in continuous cuffless BP waveform measurement.

A new particle filter algorithm filtering motion artifact noise for clean electrocardiogram signals in wearable health monitoring system.

With the evolution of wearable systems, more and more people tend to wear wearable devices for health monitoring during sports. However, a large amount of motion artifact noise is introduced at this time, which is difficult to filter out due to its stochasticity. The amplitude and characteristics of motion artifact noise vary with changes in motion intensity. In order to filter out the motion artifact noise, the paperproposes a new particle algorithm, which can detect the intensity of the motion artifact for adaptive filtering, especiallysuitable for wearable health monitoring systems. In this algorithm, variational mode decomposition was first introduced to analyze the noisy electrocardiogram (ECG) signal in order to find the clean components. Then, the Laguerre estimation technique was applied to obtain an accurate ECG polar model. Taking this model as the state equation, a particle filter algorithm was defined to filter out the motion artifact noise. In the particle filter algorithm, we defined a parameter γ whose values were obtained from the six-axis data of motion sensor MPU6050 in our wearable device. This parameter γ could reflect the current noise levels and adaptively update the particle weights. Finally, some exercise experiments proved that the parameter γ could map the motion artifacts in real time and also demonstrated the superiority of the algorithm in terms of signal-to-noise ratio improvement and error reduction compared to other algorithms. The new particle filter algorithm proposed in this paper combines the six-axis data (three-axis accelerometer and three-axis gyroscope) with the ECG signal to effectively eliminate a large amount of motion artifact noise, thus solving the problem of excess noise from wearable devices when people are exercising, allowing them to accurately obtain real-time ECG health information.

Prolonged evolution of syn-collisional progressive deformation of the Trans-North China Orogen: Structural and geochronological evidence from the Xiaoqinling region, central China

Significant understanding of the Trans-North China Orogen (TNCO) has been achieved through previous studies. However, the lack of structural analyses, especially for its southern part, has restricted our understanding of the structural evolution of the TNCO. In this contribution, we present new structural and geochronological data from the Taihua Complex of the Xiaoqinling region to reconstruct the collision-induced deformation history and provide constraints on the structural evolution of the TNCO. Paleoproterozoic collision-induced structures in the Xiaoqinling region are characterized by the development of penetrative, ductile deformation fabrics, localized ductile shear zones, and syn-shearing folds, notably sheath folds. The evolution of the folds and syn-tectonic migmatites records the occurrence of non-coaxial progressive shear deformation within ductile shear zones. Vorticity analysis confirms simple-shear-dominated general-shear deformation within the shear zones, with an increase in a pure shear component during the later stages. The integrated results, encompassing the geometry, kinematics, finite strain, and geochronology of these shear zones and folds, reveal the presence of the regional-scale, collision-induced sheath folds that were associated with low-angle thrust shear zones with WNW-directed kinematics. Deformation temperatures of 500–650 °C indicate that the ductile shear zones and simultaneous sheath folds formed during the exhumation process of the TNCO. New zircon U–Pb ages constrain the timing of the metamorphism and ductile deformation to between 1951 and 1840 Ma. Integration of this and previous dating results reveals a history of prolonged collision for the TNCO, lasting from as early as ∼ 1.97 Ga and continuing until as late as ∼ 1.84 Ga, with the earlier period of 1.97–1.88 Ga representing the continental subduction stage and the later period of 1.88–1.84 Ga corresponding to the subsequent exhumation stage. The protracted orogenic evolution for the TNCO supports the notion that large-scale collisional orogenesis can occur over such long durations (over 100 Mya). These structural and geochronological data support the orogenic model of SE-directed subduction polarity.

PSPICA Force Field Extended for Proteins and Peptides.

Many coarse-grained (CG) molecular dynamics (MD) studies have been performed to investigate biological processes involving proteins and lipids. CG force fields (FFs) in these MD studies often use implicit or nonpolar water models to reduce computational costs. CG-MD using water models cannot properly describe electrostatic screening effects owing to the hydration of ionic segments and thus cannot appropriately describe molecular events involving water channels and pores through lipid membranes. To overcome this issue, we developed a protein model in the pSPICA FF, in which a polar CG water model showing the proper dielectric response was adopted. The developed CG model greatly improved the transfer free energy profiles of charged side chain analogues across the lipid membrane. Application studies on melittin-induced membrane pores and mechanosensitive channels in lipid membranes demonstrated that CG-MDs using the pSPICA FF correctly reproduced the structure and stability of the pores and channels. Furthermore, the adsorption behavior of the highly charged nona-arginine peptides on lipid membranes changed with salt concentration, indicating the pSPICA FF is also useful for simulating protein adsorption on membrane surfaces.

Ethnophilosophical Understanding on the Existence of Ukraine: Methodological Principles

The article discusses the methodological foundations of Ukrainian studies, which take on significant existential importance for Ukraine in the conditions of the Russian-Ukrainian war. It posits that each nation formulates its own methodology of nation-defensive type, crucial for preserving its identity and distinctiveness. In these circumstances, Ukrainian axiology embodies the triad of native land, native language, and native tradition, attaining a sacred significance. Within the context of hybrid information warfare, mechanisms for creating global terminology, carrying a worldwide ideological load, are uncovered. However, under the guise of «universal» values, they subtly impose themselves on the entire world. Ivan Franko already pointed to such information strategies at the beginning of the 20th century, emphasizing the importance of trusting national thinkers to navigate global traps. The domestic definitions of ethnicity and ethnoculture, ethnoreligion and ethnophilosophy are provided, the fundamental principles of the national-existential methodology are clarified. Using examples of polar social models and archetypal worldview-antagonistic algorithms based on the age-old dichotomy of «world» and «home», it is demonstrated that global and imperial methodologies are unsuitable for ethnological studies. The essence of the «foreign» and the «native» becomes explicitly understood through such algorithms. The methodological foundation for scientific research in the field of Ukrainian studies is proposed to be founded upon ethnophilosophy (the founder of which is considered to be Volodymyr Shayan) as the most appropriate philosophy of the nation-defense type.

Evaluating the Corrosivity of Relevant Environments That Can Form on the Surface of Spent Nuclear Fuel Canisters

Austenitic stainless steels (SS), utilized extensively in coastal environments due to their enhanced corrosion resistance, are susceptible to localized corrosion and stress corrosion cracking (SCC) when exposed to chloride environments and sufficient stresses. One potential scenario under which SCC may pose a concern is the storage and eventual transport of spent nuclear fuel (SNF) in SS canisters. The SS canisters are stored in many locations across the United States and may be subjected to corrosion from brines formed by deliquescence of salt aerosols of varying compositions. Recently, the compositions of salts collected from the surface of SNF interim storage canisters at four different storage sites have been evaluated; these represent both coastal and inland sites, and widely differing compositions. The observed salt chemistries vary from laboratory salts commonly used in corrosion testing (i.e., NaCl, MgCl2, and artificial seawater). Herein, we evaluate the relative corrosivity of the brines through polarization scans, exposure tests, and modeling efforts. The results of this study are discussed in terms of potential canister degradation and improved methods to determine the corrosivity of field-relevant environments. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525. This document is SAND2023-02443C.

Analysis of influence factors of target polarization characteristics

The target polarization characteristics reflect the important information about the medium material, surface texture, and structural characteristics of the target itself. In this paper, 9 kinds of samples with different materials, roughness, and surface texture direction are selected to measure the polarization characteristics in an outdoor environment, and the influencing factors of the target polarization characteristics are analyzed, where the influence of the surface texture direction on the spatial distribution of the target polarization characteristics is emphatically analyzed. The results show that the target polarization characteristics are affected by many factors such as material, roughness, surface texture direction, and detection position, and the greater the angle between the surface texture direction and the principal plane, the more concentrated the target polarization characteristics are in and around the principal plane, which could provide a theoretical basis for comprehensively mastering the target polarization characteristics, improving the ability of target polarization detection and recognition, and enhancing the confidence of the target polarization modeling and simulation.

Beneficial effects of the precritical nonlinearities on the lateral buckling of extremely flexible beams

The lateral buckling of extremely flexible beams, uniformly or non-uniformly bent in a principal inertia plane, is studied. An exact polar continuum model of an internally constrained 1D straight beam, immersed in the 3D space, is formulated. The model is linearized in the out-of-plane displacement only, so that it is able to capture: (i) the exact planar non-trivial fundamental path, and (ii) the exact critical point along it, at which the beam experiences out-of-plane flexural–torsional buckling. It is proven that the precritical deflections increase the critical load with respect to that evaluated by the classic theory, in which a trivial fundamental path is assumed, thus playing a beneficial role. Moreover, when the beam is extremely flexible, bifurcation disappears, similar to what discussed in literature for axially soft compressed beams, although via a different mechanism of the eigenvalues.

Evaluation of Performance of Polar WRF Model in Simulating Precipitation over Qinghai-Tibet Plateau

Evaluation of Performance of Polar WRF Model in Simulating Precipitation over Qinghai-Tibet Plateau

Multidimensional clustering based fault diagnosis method for wind turbine transmission chain

Abstract With the rapid development of wind power generation, ensuring the reliability and fault diagnosis of wind turbine transmission chains has become a focal point. Traditional clustering methods that address the fault diagnosis problem in wind turbine transmission chains suffer from low fault discrimination and accuracy, as they rely on a single indicator. This paper proposes a two-dimensional clustering model that utilizes multiple indicators to address the issue of distinguishing similar faults within the wind turbine transmission chain from various perspectives and dimensions. The proposed approach involves collecting vibration signals from the transmission chain of wind turbines using sensors and using the root mean square and kurtosis of the fault signal as clustering features. A multidimensional polar coordinate clustering model is established, with the signal kurtosis representing the polar angle and the root mean square representing the polar radius. The clustering of fault signals within wind turbine transmission chains is achieved by optimizing the clustering boundaries by establishing a clustering boundary optimization equation. The results of the developed clustering model are evaluated using external and internal evaluation methods. Experimental results demonstrate that this method exhibits high accuracy and low computational complexity in diagnosing faults within wind turbine transmission chains. In comparison with other clustering methods, the proposed method outperforms them according to the experimental results. Hence, this study presents a novel approach for health monitoring and fault diagnosis of the transmission chain of wind turbines, which has significant implications for improving the reliability of wind turbine operation and reducing maintenance costs.

A graph neural network-based machine learning model for sentiment polarity and behavior identification of COVID patients

A graph neural network-based machine learning model for sentiment polarity and behavior identification of COVID patients

A continuous leakage real-time localization method based on space phase image of elastic wave field with improved CNN

To satisfy the requirement of real-time monitoring and locating of the leakage in large pressure vessels, a method of leakage source location based on improved convolutional neural network (CNN) is proposed in this paper. In this method, the polar coordinate model of elastic wave propagation excited by continues leakage is established, and the improved CNN is constructed according to its spatial field distribution, and the training set of the network is obtained by finite element simulation. The experimental results show that this method can be applied to locate the leak at any time after it occurs, and only a single sensor array is used. In the experiment of 1 m2 stiffened test plate, the absolute distance error was less than 0.1 m and the absolute angle error was less than 0.1 rad in 90.2 % of all samples.

Prelude to molecularization: The double gradient model of Sulo Toivonen and Lauri Saxén

The present molecular investigations of Organizer phenomena show a remarkable connection to the earlier classical embryological studies that used transplantation as a method for making mechanistic models of induction. One of the most prominent of these connections is the dual gradient model for anterior-posterior and dorsal-ventral polarity. This paper will discuss some of the history of how transplantation experiments provided data that could be interpreted in terms of two gradients of biologically active materials. It will highlight how the attempts to discover the elusive Induktionsstoffen gave rise to the double gradient model of Sulo Toivonen and Lauri Saxén in the 1950s and 1960s. This paper will also document how this research into the identity of these molecules gave rise to the developmental genetics that eventually would find the molecules responsible for primary embryonic induction.

Dose-dependent effect on skin permeation of polar and non-polar compounds

The study of the relationship between the amount of drug applied to the skin and fraction of drug absorbed can improve our understanding of finite-dose percutaneous absorption in the development of topical products and risk assessment of hazardous chemical exposure. It has been previously shown that an increase in the dose applied to the skin leads to a decrease in the fraction of drug permeated the skin (dose-dependent effect). The objective of this research was to examine the dose-dependent effect using permeants of varying physiochemical properties. The dose-dependent effect was studied using human epidermal membrane under finite dose conditions in Franz diffusion cell with model permeants at doses ranging from 0.1 to 200 μg. The dose-dependent effect was evident with model permeants caffeine, corticosterone, dexamethasone, and estradiol, consistent with the relationship of decreasing fraction of dose permeated the skin at increasing the applied dose. However, no significant dose-dependent effect was observed for the polar model permeants urea, mannitol, tetraethyl ammonium, and ethylene glycol, suggesting different transport mechanisms for these permeants. It was also found that, at relatively high doses, estradiol, dexamethasone, and corticosterone could increase the permeation of polar and lipophilic permeants, which could counter the dose-dependent effect under the conditions studied.

Understanding interfacial conductance in non-stoichimetric Ca x Ta y O3−δ /SrTiO3

In search of novel conducting oxide heterointerfaces, we previously uncovered an distinctive quasi two-dimensional electron gas (q-2DEG) type behaviour in non-stoichimetric CaxTayO3-δ/SrTiO3 heterostructure. However, the underlying mechanism remained enigmatic. In this study, we delve into the intricate interplay of growth conditions, stoichiometry, and transport properties of these heterostructures. Using (Ca0.5TaO3)2 Target and the pulsed laser deposition technique, we grow the epitaxial thin films while systematically varying growth parameters, inculding laser energy density, oxygen pressures, and post-deposition annealing. Structural analysis unveiled a notable presence of oxygen vacancies in the as-grown films, while annealed samples exhibited an oxygen surplus. Building upon these findings, our comprehensive charge transport measurements revealed that while oxygen vacancies do contribute to conductivity, the polar catastrophe model takes precedence as the primary source of interfacial conductance in these heterostructures. This study provides valueable insights into the behavior of these innovative heterostructures, paving the way for future advancements in the field.

Solar Wind‐Magnetosphere Coupling During High‐Intensity Long‐Duration Continuous AE Activity (HILDCAA)

AbstractHigh‐Intensity Long‐Duration Continuous AE Activity (HILDCAA) intervals are driven by High Speed solar wind Streams (HSSs) during which the rapidly‐varying interplanetary magnetic field (IMF) produces high but intermittent dayside reconnection rates. This results in several days of large, quasi‐periodic enhancements in the auroral electrojet (AE) index. There has been debate over whether the enhancements in AE are produced by substorms or whether HILDCAAs represent a distinct class of magnetospheric dynamics. We investigate 16 HILDCAA events using the expanding/contracting polar cap model as a framework to understand the magnetospheric dynamics occurring during HSSs. Each HILDCAA onset shows variations in open magnetic flux, dayside and nightside reconnection rates, the cross‐polar cap potential, and AL that are characteristic of substorms. The enhancements in AE are produced by activity in the pre‐midnight sector, which is the typical substorm onset region. The periodicities present in the intermittent IMF determine the exact nature of the activity, producing a range of behaviors from a sequence of isolated substorms, through substorms which merge into one‐another, to almost continuous geomagnetic activity. The magnitude of magnetic fluctuations, dB/dt, in the pre‐midnight sector during HSSs is sufficient to produce a significant risk of Geomagnetically Induced Currents.

THEORETICAL INVESTIGATION OF 2,6-DIFLUORO-4-NITROANILINE WITH SEMI-EMPIRICAL LEVELS OF THEORY

Abstract. In this work quantum chemical approach was applied in order to investigate the electronic structure and certain properties of 2,6-difluoro-4-nitroaniline with a series of semi-empirical methods using the GAMESS software. Protic and aprotic Polarized Continuum solvent models were used to study the influence of the media to the electronic structure and geometry of the molecule. It has been found that calculations using solvent models make possibility to obtain more accurate results than for vacuum. The comparison of calculated results with the available XRD crystallographic data shows that all obtained values are within acceptable deviations.

Three-dimensional magnetic field imaging of protoplanetary disks using Zeeman broadening and linear polarization observations

Context. Magnetic fields are predicted to have a crucial impact on the structure, evolution, and chemistry of protoplanetary disks. However, a direct detection of the magnetic field toward these objects has yet to be achieved. Aims. In order to characterize the magnetic fields of protoplanetary disks, we investigate the impact of the Zeeman effect on the (polarized) radiative transfer of emission from paramagnetic molecules excited in protoplanetary disks. Methods. While the effects of the Zeeman effect are commonly studied in the circular polarization of spectral lines, we also performed a comprehensive modeling of the Zeeman-induced broadening of spectral lines and their linear polarization. We developed simplified radiative transfer models adapted to protoplanetary disks, which we compare to full three-dimensional polarized radiative transfer simulations. Results. We find that the radiative transfer of circular polarization is heavily affected by the expected polarity change of the magnetic field between opposite sides of the disk. In contrast, Zeeman broadening and linear polarization are relatively unaffected by this sign change due to their quadratic dependence on the magnetic field. We can match our simplified radiative transfer models to full polarization modeling with high fidelity, which in turn allows us to prescribe straightforward methods to extract magnetic field information from Zeeman broadening and linear polarization observations. Conclusions. We find that Zeeman broadening and linear polarization observations are highly advantageous methods to characterize protoplanetary disk magnetic fields as they are both sensitive probes of the magnetic field and are marginally affected by any sign change of the disk magnetic field. Applying our results to existing circular polarization observations of protoplanetary disk specral lines suggests that the current upper limits on the toroidal magnetic field strengths have to be raised.

The Effect of Arctic Sea‐Ice Loss on Extratropical Cyclones

AbstractTaking advantage of the Polar Amplification Model Intercomparison Project simulations and using a Lagrangian objective feature tracking algorithm, we determine the response of extratropical cyclones to sea‐ice loss and consequent weakening of the equator‐to‐pole near‐surface temperature gradient. The wintertime storm tracks are found to shift equatorward in the North Atlantic and over Europe, and eastward in the North Pacific. In both regions, cyclones become weaker and slower, particularly on the poleward flank of the storm tracks. On average, there are fewer individual cyclones in the extratropics each winter, they last longer, are weaker, and travel more slowly. These changes are greatest over the Arctic, but still statistically significant in midlatitudes despite being small compared to internal variability. Inter‐model spread in cyclone responses are not strongly correlated with that in Arctic warming or Arctic amplification. Little change in summertime cyclones is found.