bluuebunny/crossref_metadata_2025 huggingface dataset:
MEGS: Morphological Evaluation of Galactic Structure
Authors: Çakir U. , Buck T.
Published: October 2024

Context. Understanding the morphology of galaxies is a critical aspect of astrophysics research, providing insight into the formation, evolution, and physical properties of these vast cosmic structures. Various observational and computational methods have been developed to quantify galaxy morphology, and with the advent of large galaxy simulations, the need for automated and effective classification methods has become increasingly important.

Aims. This paper investigates the use of principal component analysis (PCA) as an interpretable dimensionality reduction algorithm for galaxy morphology using the IllustrisTNG cosmological simulation dataset with the aim of developing a generative model for galaxies.

Methods. We first generate a dataset of 2D images and 3D cubes of galaxies from the IllustrisTNG simulation, focusing on the mass, metallicity, and stellar age distribution of each galaxy. PCA is then applied to this data, transforming it into a lower-dimensional image space, where closeness of data points corresponds to morphological similarity.

Results. We find that PCA can effectively capture the key morphological features of galaxies, with a significant proportion of the variance in the data being explained by a small number of components. With our method we achieve a dimensionality reduction by a factor of ~200 for 2D images and ~3650 for 3D cubes at a reconstruction accuracy below 5%.

Conclusions. Our results illustrate the potential of PCA in compressing large cosmological simulations into an interpretable generative model for galaxies that can easily be used in various downstreaming tasks such as galaxy classification and analysis.
Stable case BB/BC mass transfer to form GW190425-like massive binary neutron star mergers
Authors: Qin Ying , Zhu Jin-Ping , Meynet Georges , Zhang Bing , Wang Fa-Yin , Shu Xin-Wen , Song Han-Feng , Wang Yuan-Zhu , Yuan Liang , Wang Zhen-Han-Tao , Hu Rui-Chong , Wu Dong-Hong , Yi Shuang-Xi , Tang Qing-Wen , Wei Jun-Jie , Wu Xue-Feng , Liang En-Wei
Published: October 2024

Context. On April 25, 2019, the LIGO-Virgo Collaboration discovered a gravitational-wave (GW) signal from a binary neutron star (BNS) merger, that is, GW190425. Due to the inferred large total mass, the origin of GW190425 remains unclear.

Aims. Assuming GW190425 originated from the standard isolated binary evolution channel, its immediate progenitor is considered to be a close binary system, consisting of a He-rich star and a NS just after the common envelope phase. We aim to study the formation of GW190425 in a solar-like environment by using the detailed binary evolution code MESA.

Methods. We perform detailed stellar structure and binary evolution calculations that take into account mass loss, internal differential rotation, and tidal interactions between a He-rich star and a NS companion. We explore the parameter space of the initial binary properties, including initial NS and He-rich masses and initial orbital period.

Results. We find that the immediate post-common-envelope progenitor system, consisting of a primary ∼2.0 M⊙ (∼1.7 M⊙) NS and a secondary He-rich star with an initial mass of ∼3.0 − 5.5 M⊙ (∼5.5 − 6.0 M⊙) in a close binary with an initial period of ∼0.08 − 0.5 days (∼0.08 − 0.4 days), that experiences stable Case BB/BC mass transfer (MT) during binary evolution, can reproduce the formation of GW190425-like BNS events. Our studies reveal that the secondary He-rich star of the GW190425’s progenitor before its core collapse can be efficiently spun up through tidal interaction, finally remaining as a NS with rotational energy even reaching ∼1052 erg, which is always much higher than the neutrino-driven energy of the supernova (SN) explosion. If the newborn secondary NS is a magnetar, we expect that GW190425 can be the remnant of a magnetar-driven SN, namely a magnetar-driven ultra-stripped SN, a superluminous SN, or a broad-line Type Ic SN.

Conclusions. Our results show that GW190425 could be formed through the isolated binary evolution, which involves a stable Case BB/BC MT just after the common envelope phase. On top of that, we show the He-rich star can be tidally spun up, potentially forming a spinning magnetized NS (magnetar) during the second SN explosion.
eDIG-CHANGES
Authors: Lu Li-Yuan , Li Jiang-Tao , Vargas Carlos J. , Fang Taotao , Benjamin Robert A. , Bregman Joel N. , Dettmar Ralf-Jürgen , English Jayanne , Heald George H. , Jiang Yan , Daniel Wang Q. , Yang Yang
Published: October 2024

Context. The kinematic information of the extraplanar diffuse ionized gas (eDIG) around galaxies provides clues to the origin of the gas.

Aims. The eDIG-CHANGES project studies the physical and kinematic properties of the eDIG around the CHANG-ES sample of nearby edge-on disk galaxies.

Methods. We use a novel multi-slit narrow-band spectroscopy technique to obtain the spatial distribution of the spectral properties of the ionized gas around NGC 891, which is often regarded as an analogue of the Milky Way. We developed specific data reduction procedures for the multi-slit narrow-band spectroscopy data taken with the MDM 2.4 m telescope. The data presented in this paper cover the Hα and [N II]λλ6548, 6583 Å emission lines.

Results. The eDIG traced by the Hα and [N II] lines shows an obvious asymmetric morphology, being brighter in the northeastern part of the galactic disk and extending a few kiloparsecs above and below the disk. Global variations in the [N II]/Hα line ratio suggest additional heating mechanisms for the eDIG at large heights beyond photoionization. We also construct position-velocity (PV) diagrams of the eDIG based on our optical multi-slit spectroscopy data and compare them to similar PV diagrams constructed with the H I data. The dynamics of the two gas phases are generally consistent with each other. Modelling the rotation curves at different heights from the galactic mid-plane suggests a vertical negative gradient in turnover radius and maximum rotation velocity, with magnitudes of approximately 3 kpc kpc−1 and 22 − 25 km s−1 kpc−1, respectively.

Conclusions. Our measured vertical gradients of the rotation curve parameters suggest significant differential rotation of the ionized gas in the halo, often referred to as the lagging eDIG. Systematic study of the lagging eDIG, using the multi-slit narrow-band spectroscopy technique developed in our eDIG-CHANGES project, will help us to better understand the dynamics of the ionized gas in the halo.
A multi-instrument study of UV bursts and associated surges in AR 12957
Authors: Nelson C. J. , Calchetti D. , Gandorfer A. , Hirzberger J. , Sinjan J. , Solanki S. K. , Berghmans D. , Strecker H. , Blanco J.
Published: October 2024

Context. The relationship between UV bursts and solar surges is complex, with these events sometimes being observed together and sometimes being observed independently. Why this sporadic association exists is unknown; however, it likely relates to the physical conditions at the site of the energy release that drives these events.

Aims. Here, we aim to better understand the relationship between UV bursts and solar surges through a multi-instrument analysis of several associated events that occurred around the trailing sunspot in AR 12957.

Methods. We used data from Solar Orbiter, the Solar Dynamics Observatory (SDO), and the Interface Region Imaging Spectrograph (IRIS) to achieve our aims. These data were sampled on 3 March 2022 between 09:30:30 UT and 11:00:00 UT, during which time a coordinated observing campaign associated with the Slow Solar Wind Connection Solar Orbiter Observing Plan (SOOP) took place.

Results. Numerous small-scale negative polarity magnetic magnetic features (MMFs) were observed to move quickly (potentially up to 3.3 km s−1) away from a sunspot until they collided with a more stable positive polarity plage region around 7 Mm away. Several UV bursts were identified in IRIS slit-jaw imager (SJI) 1400 Å data co-spatial to where these opposite polarity fields interacted, with spatial scales (< 2 Mm) and lifetimes (< 20 minutes) larger than typical values for such events. Two surges were also observed to occur at these locations, with one being short (5 Mm) and hot (bright in the IRIS SJI images), whilst the other was a cooler (dark in coronal imaging channels), longer surge that appeared to fill an active region loop.

Conclusions. Magnetic reconnection between the negative polarity MMFs around the sunspot and the positive polarity plage region appears to be the driver of these events. Both the speed of the MMFs and the locally open magnetic topology of the plage region could possibly have been important for forming the surges.
Diagnostic des systèmes de production de pommier face aux changements climatiques : cas de M’semrir, Haut Atlas, Maroc
Authors: Lozzi Assia , Chakroun Rim , Hakimi Fatiha , Maatala Nassreddine , Bounadi Imane , Lahrech Taha , Bekkar Younes , Bouaziz Ahmed
Published: October 2024

Les systèmes de production pomicole dans les zones montagneuses du Haut Atlas, au Maroc, sont confrontés à des contraintes techniques et environnementales, exacerbées par les effets croissants du changement climatique. Cette étude vise à diagnostiquer les systèmes de production de pommier dans la commune de M’semrir, tout en analysant l’impact des variations climatiques locales, afin d’identifier des stratégies d’amélioration pour renforcer la durabilité et la résilience des exploitations. Les conditions climatiques arides à semi-arides donnent un rôle crucial à l’irrigation et à la gestion des ressources en eau. Trois catégories d’exploitations ont été distinguées : moyennes, petites, et micro-exploitations. Au sein de chacun de ces groupes, deux niveaux de performance ont été dégagés, principalement basés sur les rendements, la productivité de l’eau, et la productivité de l’azote. Les principaux défis rencontrés dans la majorité de ces exploitations sont des rendements modestes, une faible productivité de l’eau et une faible productivité partielle de l’engrais azoté, ce qui souligne la nécessité de stratégies d’optimisation pour améliorer l’efficacité des intrants. Une gestion plus efficace de l’irrigation, orientée vers des méthodes économes en eau, pourrait jouer un rôle clé dans la résilience des exploitations. Enfin, des stratégies proactives pour anticiper et atténuer les effets de la sécheresse apparaissent essentielles pour assurer la durabilité de ces systèmes agricoles dans un contexte climatique de plus en plus contraignant.
Frequency-resolved measurement of two-color air plasma terahertz emission
Authors: Hase Eiji , Degert Jérôme , Freysz Eric , Yasui Takeshi , Abraham Emmanuel
Published: October 2024

We investigated the far-field terahertz beam profile generated from an air plasma induced by two-color femtosecond laser pulses. Under our experimental conditions (filament length shorter than the dephasing length between the two-color pulses), using electro-optic sampling in both ZnTe (0.2–2.2 THz) and GaP (0.4–6.8 THz) crystals, and ultra-broadband ABCD technique (1–17.5 THz), we determined that the THz beam exhibits a unimodal beam pattern below 4 THz and a conical one above 6 THz. This experimental finding is consistent with theoretical studies based on the unidirectional pulse propagation equation, which predict the transition of THz emission from a flat-top profile to a conical one due to the destructive interference of THz waves emitted from the plasma filament. Our results also underscore the importance of accounting for experimental artifacts, such as photo-excited losses in silicon resulting in on-axis THz absorption along with the influence of drilled mirrors, in characterizing the complex spatial and frequency-dependent behavior of two-color plasma-induced terahertz emission.
Effect of 12 mm PIT tags on the survival, growth, and ecologically significant behaviours of juvenile critically endangered endemic Zingel asper
Authors: Závorka Libor , Aymes Jean-Christophe , Guiheneuf Alyssa , Mercier Olivier , Huger François , Bejean Mickaël , Glise Stéphane , Huchet Emmanuel , Tomanova Sylvie
Published: October 2024

Understanding the movement ecology and habitat use of freshwater fish is crucial for their conservation, with telemetry being an essential tool. Current tagging methods are restricted by the minimum body size of fish, as tags should not exceed 2% of the fish's body mass. This limitation hinders the study of juvenile small-bodied endangered species, as the reduced fitness of tagged individuals can negatively impact their populations. This study examines the feasibility of using 12-mm PIT tags on juvenile and subadult individuals (63–90 mm fork length) of the critically endangered Rhône streber, Zingel asper. Results indicate that tagging does not significantly affect survival, growth or behavioural traits, despite the tag weight being between 2.2% and 5.4% of the fish's weight. Tag retention was 100%, with 90% of individuals having the PIT tag fully encapsulated in the body cavity wall after 55 days. The only possible negative effect observed was a tendency, albeit statistically non-significant, for slower escape velocity in the smallest tagged individuals. These findings reduce the known minimum body size limit for 12-mm PIT tags for this species. However, the smallest individuals may be more sensitive to tagging, warranting careful consideration to avoid potential negative impacts on wild populations.
Evaluating dental implant stability using three devices Osstell®, Periotest®, and AnyCheck®: a clinical study
Authors: Dhahi Alamin Y. , Bede Salwan Y.
Published: October 2024

Introduction: Implant stability is usually measured with resonance frequency analysis (RFA) and damping capacity assessment (DCA). This study aimed to measure primary and secondary stabilities using 3 devices that are based on these methods, namely; RFA (Osstell®) and DCA (Periotest® and AnyCheck®) to assess the correlations of the measurements obtained by these devices and the correlations between implant stability and insertion torque. Material and Methods: This observational prospective study included 35 dental implants. The implant stability was measured using the 3 devices. Mann–Whitney U test and unpaired t-test assessed the relationship between implant stability and insertion torque, while the Spearman and Pearson correlations measured the correlation between readings collected via the 3 devices for the primary and secondary stabilities. Results: For the primary stability, there was a strong positive correlation between Osstell® and AnyCheck® and moderate negative correlations between Periotest® and both Osstell® and AnyCheck®. While for the secondary stability, strong correlations with similar patterns were observed among the 3 devices. The stability measurements showed significant relationships with the insertion torque. Conclusions: The 3 devices are reliable in measuring implant stability; also, high insertion torque can lead to improved implant stabilities (primary and secondary).
Key-area cyberspace mimic defense against data-oriented attacks
Authors: Chen Ping , Wei Jin , Yu Zhuyang , Chen Jiwei
Published: October 2024

As modern systems widely deploy protective measures for control data in memory, such as Control-Flow Integrity (CFI), attackers’ ability to manipulate control data is greatly restricted. Consequently, attackers are turning to opportunities to manipulate non-control data in memory (known as Data-Oriented Attacks, or DOAs), which have been proven to pose significant security threats to memory. However, existing techniques to mitigate DOAs often introduce significant overhead due to the indiscriminate protection of a large range of data objects. To address this challenge, this paper adopts a Cyberspace Mimic Defense (CMD) strategy, a generic framework for addressing endogenous security vulnerabilities, to prevent attackers from executing DOAs using known or unknown security flaws. Specifically, we introduce a formalized expression algorithm that assesses whether DOA attackers can construct inputs to exploit vulnerability points. Building on this, we devise a key-area CMD strategy that modifies the coded pathway from input to the vulnerability point, thereby effectively thwarting the activation of the vulnerability. Finally, our experiments on real-world applications and simulation demonstrate that the key-area CMD strategy can effectively prevent DOAs by selectively diversifying parts of the program code.
Naturheilverfahren und Komplementärmedizin: alles im Goldrahmen?
Authors: Stange Rainer
Published: October 2024

Die Komplementärmedizin sowie Naturheilverfahren sind bei Patienten in Deutschland stark nachgefragt. Auch gibt es eine große Zahl an Ärzten und medizinisch Tätigen, die diese Leistungen anbieten. Dennoch mangelt es in vielen Bereichen an Anerkennung der Komplementärmedizin von Seiten öffentlicher Einrichtungen und Institutionen wie der gesetzlichen Krankenversicherung. Rechtliche Rahmenbedingungen sowie gute qualifizierende Weiterbildungsangebote sind wichtige Faktoren, um die Rolle der Komplementärmedizin zu stärken.
A Pilot Study Using Continuous Glucose Monitoring among Patients with a Low 1-Hour Glucose Challenge Test Result versus Controls to Detect Maternal Hypoglycemia
Authors: Ding Jia Jennifer , Milley Lauren , Son Moeun
Published: October 2024

Objective A low 1-hour glucose challenge test (GCT) result (<10th percentile for population) has been associated with neonatal morbidity, including small-for-gestational-age birth weight, and it is hypothesized that underlying maternal hypoglycemia may contribute to this neonatal morbidity. We sought to assess whether eligible patients would undergo continuous glucose monitoring to allow comparison of maternal hypoglycemia between those with a low GCT result versus controls.

Study Design This exploratory study enrolled patients who completed a GCT between 24 and 30 weeks' gestation from June to September 2022. English- or Spanish-speaking participants aged ≥18 years wore a blinded continuous glucose monitor (CGM) for 10 days. There were 10 participants each in the low GCT (<82 mg/dL) and normal GCT group. Proportions were calculated to determine recruitment rates and describe the low versus normal glycemic groups across clinical and sociodemographic characteristics. Maternal hypoglycemia, defined using various proposed thresholds, was analyzed as continuous data (time duration) with Student's t-tests and categorical data (number of episodes) with chi-square tests and bivariate analyses were performed comparing participants with a low versus normal GCT. Primary outcome measures were recruitment, enrollment, and adherence rates, and overall glycemic values for each group.

Results Of 64 eligible patients, 58 (91%) were approached, and of them, 20 (35%) were enrolled. All 20 participants had CGM data to review with 100% adherence. Average glucose values were similar between participants in the low GCT and normal GCT groups (111.7 ± 18.0 vs. 111.6 ± 11.7 mg/dL, p = 0.99), and participants with a low GCT value did not demonstrate more hypoglycemia than those with a normal GCT value across five proposed thresholds on CGM analysis.

Conclusion In this pilot study, participants wore blinded CGMs to collect glycemic data, and those with a low GCT result did not experience more hypoglycemia than those with a normal GCT on CGM analysis.

Key Points
Interventional Management of Visceral Artery Aneurysms: Simple to Complex
Authors: Poyyamoli Santhosh , Cherian Mathew , Mehta Pankaj
Published: October 2024

Visceral artery aneurysms (VAAs) are uncommon but potentially life-threatening vascular disorders that can involve the celiac, superior, and inferior mesenteric arteries or their branches. They are often asymptomatic but can present with vague abdominal pain, secondary effects, or signs of hemorrhage. The most common site of involvement is the splenic artery, followed by the hepatic artery, the celiac axis, and mesenteric arterial branches. VAAs can be classified into two types: true aneurysms (TAs) and pseudoaneurysms (PSAs). Imaging, particularly multidetector computed tomography angiography, is the cornerstone in diagnosing VAAs. Treatment decisions are based on the risk of rupture and clinical deterioration in a patient with a VAA. The endovascular approach remains the mainstay in the treatment of VAAs. As a general guideline, PSAs, even when asymptomatic, should always be treated. TAs are treated based on their size and location. Deconstructive and reconstructive strategies are the standard treatment options for any VAA, and assessing the vascular anatomy and collateral circulation is paramount for treatment decisions.
NATO after the invasion of Ukraine: how the shock changed alliance cohesion
Authors: Hardt Heidi
Published: October 2024

Following Russia’s invasion of Ukraine in 2022, experts predicted a NATO revival. The record on alliance cohesion, however, is mixed. Allies achieved consensus on some issues but not others. While some Alliance politics scholars and NATO experts assert that cohesion improved, new scholarship is needed to explain the nature of and changes in cohesion across NATO’s many issue areas. Leveraging organizational change scholarship, I argue that the extent to which an exogenous shock—here, the invasion of Ukraine—aligns with NATO’s mission can explain differences in cohesion on issue areas across three realms. To test the argument, I employ discourse analysis of high-level NATO documents, leader statements, relevant quotes from allied and NATO officials and public opinion polls (2010–2024). Findings reveal the importance of an alliance’s mission for the reconfiguration of cohesion after shock, and the study offers an alternative means for explaining the ebbs and flow of alliance cohesion.
Modified stochastic diffusion particle-tracking model (MSDPTM) incorporating energy cascade theory and eddy intermittency for suspended sediment transport in open channel flow
Authors: Lin Shi-Wei , Mohan Shiv , Tsai Christina W.
Published: October 2024

This study presents a modified stochastic diffusion particle tracking model (MSDPTM) that incorporates energy cascade theory to more accurately simulate suspended sediment transport. The impact of turbulent eddies on sediment particles is an intermittent process, which is also considered in this study. The study examines the time correlation between eddies using eddy turnover time and finds that closer-scale eddies exhibit higher correlations than those farther apart. The statistical properties of particle movement, such as the ensemble mean and variance of particle trajectories, have been calculated and compared with the stochastic diffusion particle tracking model (SDPTM) results. Notably, MSDPTM with intermittency demonstrates a significantly larger ensemble mean of particle trajectories in the streamwise direction than other particle tracking models. The proposed model is validated through comparison with available data, showing its enhanced performance. The results of the simulation indicate that MSDPTM outperforms SDPTM, especially when the intermittency effect of eddies is considered.
Investigating ocean circulation dynamics through data assimilation: A mathematical study using the Stommel box model with rapid oscillatory forcings
Authors: Smith Nathaniel , Shiney-Ajay Anvaya , Fleurantin Emmanuel , Pasmans Ivo
Published: October 2024

We investigate ocean circulation changes through the lens of data assimilation using a reduced-order model. Our primary interest lies in the Stommel box model, which reveals itself to be one of the most practicable models that has the ability of reproducing the meridional overturning circulation. The Stommel box model has at most two regimes: TH (temperature driven circulation with sinking near the north pole) and SA (salinity driven with sinking near the equator). Currently, the meridional overturning is in the TH regime. Using box-averaged Met Office EN4 ocean temperature and salinity data, our goal is to provide a probability that a future regime change occurs and establish how this probability depends on the uncertainties in initial conditions, parameters, and forcings. We will achieve this using data assimilation tools and DAPPER within the Stommel box model with fast oscillatory regimes.
Unveiling the oxidation stability of 2D gallium-intercalated monolayer epitaxial graphene through correlative microscopy
Authors: El-Sherif Hesham , Pourbahari Bita , Turker Furkan , Briggs Natalie , Robinson Joshua , Bassim Nabil
Published: October 2024

The oxidation- and air-stability of 2D gallium-intercalated monolayer epitaxial graphene was determined using correlative microscopy. Site-specific studies including AFM, scanning electron microscope, cross section STEM-HAADF, and EELS revealed that the oxygen signal detected by XPS and AES analyses originated from oxidized surface carbon contaminants without the presence of oxygen at the 2D gallium layers. In addition, the air-stability of the 2D gallium was correlated with the presence of intact epitaxial graphene. The absence of graphene leads to oxidation of the 2D gallium in air, consequently losing the crystallinity of the epitaxial gallium layer. This study invokes the importance of correlative microscopy to better understand defects in 2D metals that have been recently recognized through the confinement heteroepitaxy. In addition, this study highlights the advantage of using high spatial resolution STEM techniques in comparison with XPS that has relatively lower resolution.
Elucidating temperature-dependent local structure change and optical properties in GeTe phase-change material
Authors: Mishra Amiya Kumar , Pandey Shivendra Kumar
Published: October 2024

Phase-change memory emerges as a top contender for non-volatile data storage applications. We report here a systematic change in local structure and crystallization kinetics of binary GeTe thin films using temperature-dependent resistivity measurements, which offers single-stage crystallization at around 187 °C, corroborated with x-ray diffraction. Furthermore, the change in chemical bonding upon crystallization is determined through x-ray photoelectron spectroscopy core level spectra, which reveals the existence of Ge and Te components that align with the GeTe crystal structure. Also, an investigation was carried out employing a UV–Vis–NIR spectrophotometer to explore the evolution of optical bandgaps (Eg), Tauc parameter (B) representing the local disorder, and Urbach energy (Eu) of the GeTe material, as it undergoes the transition from a disordered amorphous state to a crystalline state. As crystallization progresses, a consistent shift of Eg from 0.92 to 0.70 eV corresponds to as-deposited amorphous at room temperature and crystalline at 250 °C, respectively. In addition, the reduction in Eu (from 199.87 to 141.27 meV) and a sudden increase of B around crystallization temperature is observed upon increasing temperature, indicating direct observation of enhanced medium-range order and distortion in short-range order, respectively, in GeTe thin films, revealing improved structural and optical properties. These enhancements make the GeTe material ideal for data storage applications of phase-change memory for next-generation computing technology.
Dynamics and energy harvesting of a flow-induced snapping sheet with nonuniform stiffness distribution
Authors: Wang Zhaokun , Cui Jingyu , Zhao Fuwang , Mumtaz Qadri M. N. , Zhou Yuanye , Tang Hui
Published: October 2024

Energy harvesting through periodic snap-through of a buckled sheet has recently gained considerable attention because of its potential applications in energy harvesting in low incoming flow. Although the snapping dynamics of uniform buckled sheets has been extensively studied, the present work focuses on the energy harvesting and dynamics of a nonuniform snapping sheet with both of its ends clamped in a channel flow. The analysis reveals that the sheet undergoes periodic snap-through oscillations, with its rear half consistently serving as the main contributor to effective energy harvesting, and the potential energy contributing significantly more than the kinetic energy. Varying the stiffness difference ΔEI* shows that increasing the stiffness of the rear part and decreasing that of the fore part shifts the deformation wave toward upstream and enhances the snapping amplitude of the fore part, optimizing energy extraction. At a length compression ratio ΔL* = 0.3, the maximum potential energy is observed for ΔEI* = 1, and the total energy peaks at ΔEI* = 2. The study also identifies an optimal ΔL* = 0.4 that maximizes both total and potential energies, and triples the potential energy in comparison with ΔL* = 0.1. However, the enhancement of nonuniformity disappears at ΔL* > 0.3 for the total energy and ΔL* > 0.2 for the potential energy. These findings provide insights to aid optimization of the design and performance of snapping sheet energy harvesters.
Identifying Arnold’s tongue for digital oscillators through event-based control in phase-locked loops
Authors: Ameli Sara
Published: October 2024

Digital phase-locked loops (PLLs) are essential feedback circuits for synchronizing signals in digital communication systems. While amplitude and phase vary continuously in analog oscillators, the amplitude remains constant in digital oscillators with dynamical variations manifesting exclusively through changes in the timing of signal transitions. In this work, we introduce a novel analytically solvable event-based model for phase-locking in digital PLLs that leverages the discrete nature of digital signals. By employing a sampled control strategy, we demonstrate one-to-one and higher ratios of frequency locking under positive and negative feedback. By discretizing the continuous control signal, we drive a discrete iterative map, which we then use to derive analytical expressions for bifurcation curves, analogous to Arnold’s tongue in analog oscillators. This mathematical framework provides an analytical approach for the analysis of synchronization and phase-locking in digital oscillators. Furthermore, the event-based control presented in this work for digital oscillators paves the way for energy-efficient circuit design and optimized control strategies for future digital communication systems.
Gyrokinetic linear simulation of feedback instability in dipole magnetosphere
Authors: Nishimura Seiya , Numata Ryusuke
Published: October 2024

We perform a novel linear simulation of the feedback instability by applying a gyrokinetic model to the magnetosphere, where the geomagnetic field is modeled by a dipole magnetic field. In order to avoid huge numerical calculation costs, the effect of the fluctuating mirror force is neglected. It is found that kinetic effects, such as the finite Larmor radius effect and the electron Landau damping, strongly stabilize the feedback instability and form a peak in the perpendicular wave number spectrum of the growth rate. During the linear growth, it is observed that electron free energy has a much larger value than the electromagnetic field perturbation energy. Since such large electron free energy may lead to electron heating and acceleration, it is important to understand its generation mechanism. Analyses based on the energy conservation reveal that the coupling of the non-uniformity of the equilibrium fields along the geomagnetic field and the fluctuating electron distribution gives rise to thermodynamic power generating the electron free energy. A fine velocity space structure around an average Alfvén velocity of the fluctuating electron distribution mainly contributes to drive the thermodynamic power.
Unraveling the dynamics of firing patterns for neurons with impairment of sodium channels
Authors: Zhang Yuancheng , Yang Dahai , Fan Dingkun , Wang Hengtong , Chen Yan , Chen Yong
Published: October 2024

Various factors such as mechanical trauma, chemical trauma, local ischemia, and inflammation can impair voltage-gated sodium channels (Nav) in neurons. These impairments lead to a distinctive leftward shift in the activation and inactivation curves of voltage-gated sodium channels. The resulting sodium channel impairments in neurons are known to affect firing patterns, which play a significant role in neuronal activities within the nervous system. However, the underlying dynamic mechanism for the emergence of these firing patterns remains unclear. In this study, we systematically investigated the effects of sodium channel dysfunction on individual neuronal dynamics and firing patterns. By employing codimension-1 bifurcation analysis, we revealed the underlying dynamical mechanism responsible for the generation of different firing patterns. Additionally, through codimension-2 bifurcation analysis, we theoretically determined the distribution of firing patterns on different parameter planes. Our results indicate that the firing patterns of impaired neurons are regulated by multiple parameters, with firing pattern transitions caused by the degree of sodium channel impairment being more diverse than those caused by the ratio of impaired sodium channel and current. Furthermore, we observed that the firing pattern of tonic firing is more likely to be the norm in impaired sodium channel neurons, providing valuable insights into the signaling of impaired neurons. Overall, our findings highlight the intricate relationships among sodium channel impairments, neuronal dynamics, and firing patterns, shedding light on the impact of disruptions in ion concentration gradients on neuronal function.
Assessing thermal resistance in fusion bond layers of 3D heterogeneous electronics packaging
Authors: Zandavi S. Hadi , Schmidt Aaron , Brun Xavier
Published: October 2024

We investigated thermal management challenges in semiconductor devices that use fusion bonding, with a focus on measuring the thermal resistance of the bonded interface. Starting with two fusion-bonded silicon wafers, we thinned the top wafer to below 100 μm and used frequency domain thermoreflectance to measure the effective thermal boundary resistance of the fusion bond. We established the measurement uncertainty with a multilayer thermal diffusion model, considering the effects of the top Si layer thickness and laser spot size. The thermal boundary resistance was measured to be 0.2 and 0.5  m2K/MW for two types of bonded wafers, with total SiO2 film thicknesses of 200 and 470 nm at the fusion bond layer, respectively. We also created defects at the interface and imaged these defects with the thermal phase response at specific frequencies chosen according to a thermal model. The method described can be applied to other types of wafer-to-wafer or die-to-die bonding including direct, polymeric, and metallic bonds.
A compact solid-state high repetition rate trigger based on a spiral generator
Authors: Sun Jingjing , Yu Ruixin , Yang Shuang , Zhang Hanwen , Sun Yijie , Li Diangeng , Ren Xiaojing , Gao Jingming , Yang Hanwu
Published: October 2024

The trigger generator made with a spiral generator (SG) has the advantages of light weight, compact structure, and low cost and has promising applications in the pulsed power field. This paper introduces a compact solid-state high-voltage pulse trigger system based on an improved SG, which has improved repetition rate and lowered the demands for semiconductor switches’ maximum current and current rise rate when compared with previous studies. The improvement is achieved by winding outward an additional layer of the passive layer and low-voltage metal strip, which realizes a significant reduction of the peak current and current rise rate of the discharge switch. The final dimension of the trigger is 25 × 10 × 10 cm3, excluding the power supply. An experiment carried out in single shot mode shows that the peak value of the output pulse can reach 50 kV with a leading edge of 57 ns. Repetitive experiments were carried out up to 1 kHz, with the peak voltage of the output pulse being 30.5 kV, the leading edge being 48 ns, and the jitter being 0.84 ns. Finally, the generator is used to trigger a gas switch, and it works stably and reliably.
Spectral broadening and vibronic dynamics of the S2 state of canthaxanthin in the orange carotenoid protein
Authors: Yang Kunwei , Mohan T. M. Nila , Rose Justin B. , Leslie Chase H. , Sutter Markus , Kerfeld Cheryl A. , Beck Warren F.
Published: October 2024

We have performed a series of broadband multidimensional electronic spectroscopy experiments to probe the electronic and vibrational dynamics of the canthaxanthin chromophore of the Orange Carotenoid Protein (OCP) from Synechocystis sp. PCC 6803 in its photoactivated red state, OCPR. Cross-peaks observed below the diagonal of the two-dimensional electronic spectrum indicate that absorption transitions prepare the bright S2 state of the ketocarotenoid canthaxanthin near to a sequence of conical intersections, allowing passage to the dark S1 state via the Sx intermediate in <50 fs. Rapid damping of excited-state coherent wavepacket motions suggests that the branching coordinates of the conical intersections include out-of-plane deformation and C=C stretching coordinates of the π-conjugated isoprenoid backbone. The unusual proximity of the Franck–Condon S2 state structure to the conical intersections with Sx and S1 suggests that the protein surroundings of canthaxanthin prepare it to function as an excitation energy trap in the OCPR–phycobilisome complex. Numerical simulations using the multimode Brownian oscillator model demonstrate that the ground-state absorption spectrum of OCPR overlaps with the fluorescence emission spectrum of allophycocyanin due to spectral broadening derived especially from the intramolecular motions of the canthaxanthin chromophore in its binding site.
Excitation of high-quality quasi-BIC toroidal mode in a lattice perturbed terahertz metasurface
Authors: Bhowmik Bhairov Kumar , Rohith K M , Duhan Pardeep , Kumar Gagan
Published: October 2024

The bound state in continuum (BIC) is a phenomenon that describes the existence of nonradiative modes (dark modes) embedded in the continuum frequency range. However, an ideal BIC cannot be detected experimentally. The BIC can be transformed into a quasi-BIC by establishing a leaky channel to the radiation continuum. In this study, instead of the conventional asymmetric split ring resonator structure, a sharp quasi-BIC mode is excited in a symmetric split ring resonator (SRR) metasurface by the perturbation of the lattice constant of the unit cell via changing the interspacing distance between two adjacent SRRs. The quality factor of the quasi-BIC mode can be tuned by varying the interspacing of two SRRs, while the resonance frequency of the quasi-BIC mode remains stable. An eigenmode analysis confirms the presence of the quasi-BIC mode, while the ab initio Fano theory and a coupled oscillator model elucidate the radiative and nonradiative coupling mechanisms. The influence of geometric perturbations on the quasi-BIC mode is quantitatively assessed through the extracted fitting parameters, providing insights into the transition from the dark mode (ideal BIC) to the quasi-BIC mode. The terahertz time domain spectroscopy measurement demonstrates a signature of the quasi-BIC resonance mode as a result of the band folding in the first Brillouin zone induced by the doubling of the lattice constant.
Critical radius deviated from Leidenfrost state of droplets on liquid layer
Authors: Chen Chen , Shi Wan-Yuan , Feng Lin
Published: October 2024

The levitation of Leidenfrost droplets on liquid pool is fascinating, but its final stage is lack of understanding. Here, we found that a droplet levitated on liquid layer eventually deviated from Leidenfrost state once its radius was lower than a critical radius due to evaporation. The critical radius of ethanol droplet deviated from Leidenfrost state on silicone oils with a thickness ranging from 2.0 to 15.0 mm was determined by experiment. The influences of the initial radius of droplet, viscosity, and thickness of liquid layer on critical radius were analyzed. In addition, the critical radius decreases with increase in superheat for ΔT lower than 25.0 °C, whereas it does not significantly vary after ΔT exceeding 25.0 °C. The bottom temperature Tb of droplet does not approach to saturation temperature even under a high superheat. The experiment found that Marangoni convection existed inside droplet. Based on a theoretical model considering Marangoni convection, the reason for droplet deviated from Leidenfrost state was explained. These findings are helpful for understanding the final state of Leidenfrost droplet on liquid layer and would provide a potential practical application such as extinction of oil pool fires with liquids.
Magnon confinement in a nanomagnonic waveguide by a magnetic Moiré superlattice
Authors: Chen Jilei , Madami Marco , Gubbiotti Gianluca , Yu Haiming
Published: October 2024

The study of moiré superlattices has revealed intriguing phenomena in electronic systems, including unconventional superconductivity and ferromagnetism observed in magic-angle bilayer graphene. This approach has recently been adapted to the field of magnonics. In this Letter, we investigate the confinement of spin waves in a nanomagnonic waveguide integrated on top of a magnetic moiré superlattice. Our numerical analysis reveals a magnonic flatband at the center of the Brillouin zone, created by a 3.5° twist in the moiré superlattice. The flatband, characterized by a high magnon density of states and a zero group velocity, allows for the confinement of magnons within the AB stacking region. The flatband results from the mode anticrossing of several different magnon bands, covering a wavevector range of nearly 40 rad/μm and a 166 nm wide spatial distribution of the magnon trapping in the waveguide. Our results pave the way for nanomagnonic devices and circuits based on spin-wave trapping in magnon waveguides.
Differentially heterogeneous hydration environment of the familial mutants of α-synuclein
Authors: Aggarwal Leena , Karmakar Sayan , Biswas Parbati
Published: October 2024

The behavior of hydration water around familial Parkinson’s disease linked mutants of α-synuclein may be linked to the early-onset of Parkinson’s disease. For the first time, this study compares the local structure and dynamics of hydration water around different segments of some of the natural mutants of α-synuclein, i.e., E46K, G51D, A30P, and A53E, with that of the wild-type protein through explicit water MD simulations. The results show that the C-terminal segments of the fast aggregating mutants such as E46K and A30P are less exposed to water, while those of the slow aggregating ones such as A53E and G51D are more exposed to water relative to that of the wild-type protein. In addition, the water molecules are found to be more ordered around the C-terminal segment of the A53E and G51D mutants as compared to the wild-type protein. This is due to an increase in the overall charge of α-syn upon A53E and G51D mutations. The translational and rotational motions of water molecules in the hydration shell of the C-terminal segment of A53E and G51D mutants are found to be faster relative to that of the wild-type protein. This study validates the differential hydration environment around the C-terminal segment for the causative and protective mutants of α-synuclein.
An improved implicit direct-forcing immersed boundary method (DF-IBM) around arbitrarily moving rigid structures
Authors: Farah E. , Ouahsine A. , Verdin P. G.
Published: October 2024

An improved implicit direct-forcing immersed boundary method (DF-IBM) is presented for simulating incompressible flows around complex rigid structures undergoing arbitrary motion. The current approach harnesses the pressure implicit with splitting of operators algorithm to handle the fluid–solid system's dual constraints in a segregated manner. As a result, the divergence-free condition is preserved throughout the Eulerian domain, and the no-slip velocity boundary condition is exactly enforced on the immersed boundary. A new pressure Poisson equation (PPE) is derived, incorporating the boundary force where the no-slip condition is already met, enabling the use of fast iterative PPE solvers without modifications. The improvement involves integrating Lagrangian weight methods having better reciprocity over the IBM-related linear operators with the implicit formulation. An additional force initialization scheme is introduced to further boost the algorithm's performance. The method's accuracy, efficiency, and capability are verified through various stationary and moving immersed boundary cases. The results are validated against experimental and numerical data from the literature. The proposed improvements seamlessly integrate into existing incompressible fluid solvers with minimal adjustments to the original system equations, highlighting their ease of implementation.
Investigating the advantages of internal impact in high-performance lightweight ultra-low-frequency rotational energy harvesters
Authors: Wang Xiying , Fang Shitong , Lai Zhihui , Zhou Shengxi , Liao Wei-Hsin
Published: October 2024

Piezoelectric energy harvesters are promising for collecting energy from ultra-low-frequency rotational machines due to their small-scale and lightweight characteristics. However, the power output for the reported rotational piezoelectric energy harvesters can hardly reach the milliwatt level, limiting their applications in sensor systems with high power consumption. To overcome this challenge, this Letter proposes an approach of using the internal impact mechanism to achieve high-performance lightweight ultra-low-frequency rotational energy harvesters. The internal impact is achieved by utilizing the velocity difference between a sliding mass and a tube on a piezoelectric beam. Through mathematical modeling and experimental validation, it is demonstrated that the velocity difference exists at ultra-low-rotational frequencies without a defined frequency lower limit, thus increasing the vibration amplitude of beam and enhancing the power output. The results show that the impact system achieves up to 136 times increase in power output compared to the non-impact system. With a maximum power output of 2.97 mW and a power density of 169.19 μW/g, the proposed energy harvester significantly outperforms the previously reported lightweight ultra-low-frequency rotational energy harvesters and shows great potential in self-powered sensing and monitoring of ultra-low-frequency rotational machines.
Role of voltage-controlled magnetic anisotropy in the recent development of magnonics and spintronics
Authors: Rana Bivas
Published: October 2024

With significant recent progress in the thin film deposition and nanofabrication technology, a number of physical phenomena occur at the interfaces of magnetic thin films, and their heterostructures have been discovered. Consequently, the electric field-induced modulation of those interfacial properties mediated through spin–orbit coupling promises to develop magnetic material based smarter, faster, miniaturized, energy efficient spintronic devices. Among them, the electric field-induced modification of interfacial magnetic anisotropy, popularly termed as voltage-controlled magnetic anisotropy (VCMA), has attracted special attention because of its salient features. This article is devoted to reviewing the recent development of magnonics, which deals with collective precessional motion of ordered magnetic spins, i.e., spin waves (SWs), and skyrmions with chiral spin textures, with VCMA, including the perspectives of this research field. Starting with a broad introduction, the key features of VCMA and its advantages over other electric field-induced methods are highlighted. These are followed by describing the state-of-the-art of VCMA, and various other direct and indirect electric field-induced methods for magnetization reversal; controlling skyrmion dynamics; excitation, manipulation, and channeling of SWs; and tailoring magnonic bands. The critical challenges, their possible solutions, and future perspectives of this field are thoroughly discussed throughout the article.