bluuebunny/crossref_metadata_2025 huggingface dataset:
Buoyancy glitches in pulsating stars revisited
Authors: Cunha Margarida S. , Damasceno Yuri C. , Amaral Juliana , Falorca Anselmo , Christensen-Dalsgaard Jørgen , Avelino Pedro P.
Published: April 2024

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.
Quasars as standard candles
Authors: Signorini Matilde , Risaliti Guido , Lusso Elisabeta , Nardini Emanuele , Bargiacchi Giada , Sacchi Andrea , Trefoloni Bartolomeo
Published: April 2024

A characteristic feature of quasars is the observed non-linear relationship between their monochromatic luminosities at rest-frame 2500 Å and 2 keV. This relationship is evident across all redshifts and luminosities and, due to its non-linearity, can be implemented to estimate quasar distances and construct a Hubble Diagram for quasars. Historically, a significant challenge in the cosmological application of this relation has been its high observed dispersion. Recent studies have demonstrated that this dispersion can be reduced by excluding biased objects from the sample. Nevertheless, the dispersion remains considerable (δ ∼ 0.20 dex), especially when compared to the Phillips relation for supernovae Ia. Given the absence of a comprehensive physical model for the relation, it remains unclear how much of the remaining dispersion is tied to the physical mechanism behind the relation itself and how much can be attributed to other factors, not addressed by the sample selection and by the choice of X-ray and UV indicators. Potential contributing factors include (i) the scatter produced by using X-ray photometric results instead of spectroscopic ones, (ii) the intrinsic variability of quasars, and (iii) the inclination of the accretion disc relative to our line of sight. In this study, we thoroughly examine these three factors and quantify their individual contributions to the observed dispersion. Based on our findings, we argue that the characteristic dispersion of the X-ray–UV luminosity relationship (which is attributable to the physical mechanism behind it) is likely below 0.06 dex. This result reinforces the validity of using quasars as standard candles and offers valuable insights for developing physical models of the X-ray/UV relation. Achieving such a low dispersion on large observed data sets is hardly feasible, due to the complexity of removing all the empirical contributions to the scatter. Nevertheless, we argue that high-redshift subsamples can show a significantly lower dispersion than the average subsample. This aspect is particularly significant for cosmological applications, indicating that targeted observations of select high-redshift objects can enhance the cosmological power of quasars in constraining the shape of the Hubble Diagram at high redshift.
Exploring the dependence of chemical traits on metallicity
Authors: Vitali S. , Slumstrup D. , Jofré P. , Casamiquela L. , Korhonen H. , Blanco-Cuaresma S. , Winther M. L. , Aguirre Børsen-Koch V.
Published: April 2024

Context. Given the massive spectroscopic surveys and the Gaia mission, the Milky Way has turned into a unique laboratory to be explored using abundance ratios that show a strong dependence on time. Within this framework, the data provided through asteroseismology serve as a valuable complement. Even so, it has been demonstrated that chemical traits cannot be used as universal relations across the Galaxy.

Aims. To complete this picture, it is important to investigate the dependence on metallicity of the chemical ratios employed for inferring stellar ages. We aim to explore different combinations of neutron-capture, odd-Z, and α elements as a function of age, particularly focusing on their metallicity dependence for a sample of 74 giant field stars.

Methods. Using UVES observations, we derived atmospheric parameters and high-precision line-by-line chemical abundances (< 0.04 dex) for the entire set of spectra, which covers a wide spread in ages (up to 14 Gyr) and metallicities (−0.7 < [Fe/H] < +0.1). Stellar ages are inferred from astereoseismic information.

Results. By fitting chemical-age trends for three different metallicity groups, we estimated their dependence on metallicity. Simultaneously, we identified those exhibiting stronger correlations with time. We found that the stronger chemical-age relations ([Zr/α]) are not necessarily the ratios with the smaller dependence on metallicity ([Ce/α] and [Ce/Eu]).

Conclusions. We confirm the [n-capture/α]-age trends for evolved stars, wherein the most significant correlation is evident in stars with solar metallicity, gradually diminishing in stars with lower iron content. The lack of homogeneity within the metallicity range highlights the intricate nature of our Galaxy’s star formation history and yield production. The dependence on metallicity of the yields involving s-process elements and the influence of radial stellar migration pose challenges to relying solely on chemical abundances for dating stars. These findings contest the feasibility of establishing universally applicable chemical clocks that are valid across the entire Galaxy and across various metallicity ranges.
Structure formation with primordial black holes to alleviate early star formation tension revealed by JWST
Authors: Colazo P. E. , Stasyszyn F. , Padilla N.
Published: April 2024

Context. This Letter explores the potential role of primordial black holes (PBHs) to address cosmological tensions as the presence of more massive than expected galaxies at high redshifts, as indicated by recent James Webb Space Telescope observations.

Aims. Motivated by inflation models that enhance the power at scales beyond the observable range that produce PBHs with Schechter-like mass functions, we aim to explain the excess of high redshift galaxies via a modification of the Λ cold dark matter power spectrum that consists in adding (i) a blue spectral index nb at kpiv = 10/Mpc and (ii) Poisson and isocurvature contributions from massive PBHs that only make up 0.5% of the dark matter.

Methods. We simulated these models using the SWIFT code and find an increased abundance of high redshift galaxies in simulations that include PBHs. We compared these models to estimates from James Webb Space Telescope observations.

Results. Unlike the Λ cold dark matter model, the inclusion of PBHs allowed us to reproduce the observations with reasonable values for the star formation efficiency. Furthermore, the power spectra we adopted potentially produce PBHs that can serve as seeds for supermassive black holes with masses 7.57 × 104 M⊙.
A Small Morphism for which the Fixed Point has an Abelian Critical Exponent Less than 2
Authors: Currie James D. , Rampersad Narad
Published: April 2024

It is known that there are infinite words over finite alphabets with Abelian critical exponent arbitrarily close to 1; however, the construction previously used involves huge alphabets. In this note we give a short cyclic morphism (length 13) over an 8-letter alphabet for which the fixed point has an Abelian critical exponent less than 1.8.
Research on energy-saving lighting control of high-rise building by the PID control algorithm
Authors: Yang Qiong , Yue Zixuan
Published: April 2024

The lighting of high-rise buildings consumes a significant amount of electricity, making it essential to implement energy-saving measures. In this paper, the lighting of high-rise buildings was briefly analyzed, followed by a description of the proportion, integration, and differentiation (PID) control algorithm. To improve the efficiency of lighting control for energy conservation, the fuzzy PID control algorithm was analyzed. The self-tuning of parameters was achieved by utilizing the whale optimization algorithm (WOA) to develop a WOA-fuzzy PID control algorithm. Finally, experimental analysis was carried out. The simulation findings showed that the WOA-fuzzy PID algorithm had the shortest stabilization time (6.77 s), the smallest maximum overshoot (3.12%), and better anti-interference capability compared to the PID and fuzzy PID algorithms. Finally, it was found from practical application that the use of the WOA-optimized algorithm resulted in a 43.7% reduction in monthly electricity consumption. The findings suggest the effectiveness of the WOA-fuzzy PID algorithm in energy-efficient lighting control and its applicability to real-world high-rise buildings.
Kein Fall gleicht dem anderen – Symptomatische Hypermobilität
Authors: Hoch Tanja
Published: April 2024

Die Suche nach dem Grund für scheinbar zusammenhangslose, rezidivierende oder chronische Beschwerden ist für hypermobile Menschen zäh. Suchen sie ärztlichen Rat, erhalten sie oft Fehldiagnosen wie Fibromyalgie oder ein chronisches Fatigue-Syndrom. Im schlimmsten Fall werden sie nicht ernst genommen und landen in der Psychosomatik-Schublade. Ein Artikel, der Physiotherapeut*innen für die Diagnose der symptomatischen Hypermobilität sensibilisiert.
Spielerisches Training – Exergames in der Physiotherapie
Authors: Franke Marie , Averbeck Ines
Published: April 2024

Schmerzen lindern, beweglicher werden, Verletzungen und Krankheiten vorbeugen – Physiotherapie ist wichtig. Doch Patient*innen empfinden die Übungen mitunter als langweilig. Und die Erfolge sind oft erst spät erkennbar. Exergames liefern eine Alternative: Abwechslungsreiche Bewegungsspiele verknüpft mit körperlichen Übungen steigern die Motivation und bieten ein sofortiges Feedback – auch für Ältere.
Physiotherapie – ein weisser Beruf – Rassistische Reproduktionen in der Physiotherapie
Authors: Pook-Sisawo Caroline
Published: April 2024

Internationale Forschungsarbeiten belegen, dass in den USA, Kanada und Großbritannien rassistische Werte und Normen den Beruf der Physiotherapie bestimmen. Nicht-weiße Therapeut*innen haben es dort ungleich schwerer, sich mit ihrem Beruf zu identifizieren. Sie erleben Stereotypisierung, Marginalisierung, Othering und Dehumanisierung. Eine kritische Auseinandersetzung mit dem Thema Rassismus in der deutschen Physiotherapie ist längst überfällig.
Erfassung der Partnerschaftszufriedenheit mit vier Items?
Psychometrische Evaluation der deutschen Version einer Kurzform der Dyadic
Adjustment Scale (DAS-4)
Authors: Lübke Laura , Flemming Eva , Müller Sascha , Brähler Elmar , Fegert Jörg M. , Spitzer Carsten
Published: April 2024

Die Qualität der Paarbeziehung eines Menschen spielt eine zentrale Rolle für das
individuelle Wohlbefinden sowie die seelische und körperliche Gesundheit. Trotz
ihrer großen Bedeutung gibt es nur wenige ultrakurze, d. h.
anwendungsökonomische Selbstbeurteilungsverfahren. Die aus vier Items bestehende
Kurzversion der Dyadic Adjustment Scale (DAS-4) stellt eine Ausnahme dar, die
sich international zunehmender Beliebtheit erfreut. In dieser Studie wurde die
deutsche Version der DAS-4 erstmalig an einer Stichprobe von Personen aus der
Allgemeinbevölkerung, welche sich in einer festen Partnerschaft befinden
(N=1296), im Hinblick auf ihre psychometrischen Eigenschaften überprüft. Neben
befriedigenden teststatistischen Itemkennwerten wies das eindimensionale
konfirmatorische Messmodell eine ausreichende Anpassungsgüte auf und die interne
Konsistenz lag im zufriedenstellenden Bereich (ω=0,80). Es zeigte sich, dass
Messinvarianz für Männer und Frauen basierend auf dem latenten Konstrukt der
DAS-4 angenommen werden kann. Hypothesenkonform fanden sich Assoziationen der
DAS-4 mit dem Geschlecht, der allgemeinen Lebenszufriedenheit, Psychopathologie
und Bindungsstilen, was auf eine angemessene Konstruktvalidität schließen lässt.
Trotz ausstehender Anwendungserfahrungen und psychometrischer Analysen der DAS-4
bei relevanten Zielgruppen wie Probanden und Probandinnen in Paarberatung bzw.
-therapie, kann das mit vier Items sehr anwendungsökonomische Verfahren zur
orientierenden Erfassung der Partnerschaftszufriedenheit empfohlen werden.
Kontroverse um Modic Changes – Ein Update
Authors: Rosenbaum Mathias
Published: April 2024

Über zehn Jahre nachdem Dr. Hanne Albert ihre bahnbrechenden Erkenntnisse veröffentlicht und die „Modic Antibiotic Spine Therapy“ initiiert hat, gilt es nun ein paar Fragen zu stellen. Waren die Erkenntnisse relevant? Hat es die Therapie von Menschen mit Modic 1 Changes grundlegend verändert? Ein Update.
Die Etablierung des Wahlfachs „Öffentliches Gesundheitswesen“ im
Praktischen Jahr für Medizinstudierende der Universitätsmedizin Göttingen –
Ergebnisse aus dem UNITE-Projekt
Authors: Demmer Iris , Espe Lia , Biermann Sina , Hummers Eva , Mayr Eckart , Puls Angelika
Published: April 2024

Hintergrund Internationale und nationale Rahmenwerke und Initiativen
fordern die Stärkung der Ausbildung von Gesundheitsprofessionen im Öffentlichen
Gesundheitsdienst (ÖGD) durch Kooperationen mit Hochschulen. Die Ärztliche
Approbationsordnung (ÄApprO) vom 21.09.2021 sieht für Medizinstudierende in
Deutschland seit dem 1. Mai 2022 eine Integration des ÖGD in die medizinische
Ausbildung im Praktischen Jahr (PJ) vor. Der Projektbericht stellt die
Vorgehensweise und Ergebnisse der Implementierung des PJ-Wahlfaches Öffentliches
Gesundheitswesen (ÖGW) für Medizinstudierende der Universitätsmedizin Göttingen
(UMG) in Kooperation mit dem örtlichen Gesundheitsamt vor.

Methoden In dem zwölfmonatigen Projekt UNITE (07/21-06/22) wurde das
PJ-Wahlfach ÖGW in sieben Schritten etabliert: Analyse der Rahmenbedingungen,
Konzeption des Wahlfaches, Erstellung eines Logbuches, Pilotphase mit fünf
Studierenden in einwöchigen Rotationen, Öffentlichkeitsarbeit für Studierende,
Einführung einer medizindidaktischen Schulung für Mitarbeitende des
Gesundheitsamtes und Umsetzung des Wahlfaches ÖGW mit PJ-Studierenden.

Ergebnisse Ein Kooperationsvertrag für die UMG und das Gesundheitsamt für
Stadt und Landkreis Göttingen regelt die Zusammenarbeit zur Ausbildung
Medizinstudierender im PJ. Die Studierenden absolvieren vierwöchige Rotationen
in die Bereiche Amtsärztlicher Dienst und Bestattungswesen, Kinder- und
Jugendmedizinischer Dienst, Infektionsschutz und Sozialpsychiatrischer Dienst.
Das Logbuch für Studierende enthält Lernziele für die einzelnen Fachdienste zur
Selbsteinschätzung der erlangten Kompetenzen. Die Didaktikschulung wurde mit
hohem Lernerfolg der teilnehmenden Mitarbeitenden umgesetzt. Drei Studierende
haben das PJ-Wahlfach erfolgreich absolviert.

Schlussfolgerungen Die Etablierung des PJ-Wahlfaches ÖGW stärkt die
Verankerung öffentlicher Gesundheitsthemen in der Ausbildung Medizinstudierender
am Standort Göttingen und macht das ÖGW als berufliche Perspektive sichtbarer.
Wesentlich für die erfolgreiche Umsetzung waren der Aufbau einer
kontinuierlichen Kooperation zwischen Universität und Gesundheitsamt, eine
studierendenorientierte Ausrichtung des Lehr- Lernkonzeptes mit einem
standortpassenden Logbuch, ein geschultes multiprofessionelles Team im
Gesundheitsamt und die Evaluation des PJ-Wahlfachs zur Qualitätssicherung und
Weiterentwicklung der PJ-Ausbildung. Das dargelegte Konzept kann andere
Standorten bei der Etablierung des PJs im ÖDG unterstützen und auf spezifische
Vorortbedingungen angepasst werden.
ortho-Halobenzyl Halides as Precursors for the Synthesis of Five- to Nine-Membered Ring Structures Employing Transition Metals as Catalysts
Authors: Aljaar Nayyef , Malakar Chandi C. , Shtaiwi Majed , Ali Basem F. , Al-Refai Mahmoud , Kant Kamal , Bliss Ng Shereinai , Al-Noaimi Mousa , Al-Momani Lo'ay Ahmed
Published: April 2024

This review highlights the multifaceted usefulness of o-halobenzyl halides as pivotal substrates for the construction of five- to nine-membered cyclic structures with the aid of transition metals as catalysts. These privileged entities engage dual active sites, enabling the combination of both intermolecular benzylation and intramolecular arylation strategies that directs the formation of a diverse repository of cyclic structures. The introduction of transition-metal catalysis in cross-coupling transformations sparked a revolution in forging aryl–heteroatom bonds, culminating in the evolution of more potent methodologies for the synthesis of a wide spectrum of valuable compounds. Furthermore, the associated pharmaceutical and biological attributes of these cyclic structures augment their significance in medicinal chemistry research. This review aims to showcase the importance of this synthetic methodology and its far-reaching applications in synthesis.

1 Introduction

2 Synthesis of Five-Membered Rings

3 Synthesis of Six-Membered Rings

4 Synthesis of Seven-Membered Rings

5 Synthesis of Eight- and Nine-Membered Rings

6 Conclusion
A Rare Case of Biliary Atresia with Biliary Ascites on a (Hepatobiliary Iminodiacetic Acid) HIDA Scan
Authors: Loyal Poonamjeet Kaur , Makhdomi Khalid , Gitau Samuel
Published: April 2024

Biliary atresia is one of the most challenging conditions in pediatric surgery even when it is the only finding. Here we present a rare case of biliary atresia complicated with biliary ascites due to ductal perforation identified on a hepatobiliary iminodiacetic acid (HIDA) scan.
Síndrome da dor complexa regional
Authors: Giostri Giana Silveira , Souza Camila Deneka Arantes
Published: April 2024

A Síndrome da Dor Complexa Regional é caracterizada por dor regional desproporcional ao evento desencadeante, sem distribuição para dermátomos, com tendência a cronicidade e disfunção. Esta revisão narrativa propõe a atualização de critérios para o diagnóstico e condução da síndrome explicitando dados da epidemiologia, etiologia, fisiopatologia. Baseamo-nos em revisões sistemáticas, narrativas e diretrizes publicadas nos últimos anos, procurando facilitar a suspeição diagnóstica e proporcionando visão ampla de possibilidades terapêuticas.
Tight Junction Proteins as Therapeutic Targets to Treat Liver Fibrosis and Hepatocellular Carcinoma
Authors: Saviano Antonio , Roehlen Natascha , Baumert Thomas F.
Published: April 2024

In the last decade tight junction proteins exposed at the surface of liver or cancer cells have been uncovered as mediators of liver disease biology: Claudin-1 and Occludin are host factors for hepatitis C virus entry and Claudin-1 has been identified as a driver for liver fibrosis and hepatocellular carcinoma (HCC). Moreover, Claudins have emerged as therapeutic targets for liver disease and HCC. CLDN1 expression is upregulated in liver fibrosis and HCC. Monoclonal antibodies (mAbs) targeting Claudin-1 have completed preclinical proof-of-concept studies for treatment of liver fibrosis and HCC and are currently in clinical development for advanced liver fibrosis. Claudin-6 overexpression is associated with an HCC aggressive phenotype and treatment resistance. Claudin-6 mAbs or chimeric antigen receptor-T cells therapies are currently being clinically investigated for Claudin-6 overexpressing tumors. In conclusion, targeting Claudin proteins offers a novel clinical opportunity for the treatment of patients with advanced liver fibrosis and HCC.
The extimate essence of speculation
Authors: Vranešević Goran
Published: April 2024

The article seeks to delineate the often misunderstood idea of speculation that has conceptually been converted from an epitome of pure thought into an economic category of profitability and self-interest. But to define speculation already means to pose a problem. In Augustine speculation designates the mutual relationship between reflection and the mirrored appearance of God’s gaze. This dictates an unattainable task of catching God’s gaze, which is more inward than my innermost self and which models our thoughts accordingly. Such extimate activity as defined by Lacan is the formal condition for the construction of visibility and is inscribed into contemplation. The article postulates that this fundamental discrepancy was also the foundation upon which Hegel carved a positive determination of thought.
Thermal cycle stability and microstructure of Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals
Authors: Liang Min , Xiong Ruibin , Chen Shuli , Wang Zujian , Su Bin , Su Rongbing , Liu Ying , He Chao
Published: April 2024

The Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) ferroelectric single crystals have been commercially available as important components in medical ultrasound transducers due to their excellent piezoelectric and electromechanical coupling performance. The variation in piezoelectric and dielectric properties of PMN-PT single crystals with ambient temperature is an important application indicator. In this work, the PMN-PT single crystals after direct current poling (DCP) and alternating current poling (ACP) were subjected to the cyclic thermal treatment process. The thermal cycling stability and microstructural changes in PMN-PT single crystals were investigated. The ACP single crystals exhibit a higher dielectric constant ε33T/ε0 (6500–7600) and piezoelectric coefficient d33 (2100–2500 pC N−1) compared to the DCP single crystals (ε33T/ε0 of 4100–5000, d33 of 1200–1300 pC N−1). Under thermal cycling at 60 °C, the DCP and ACP single crystals exhibit good thermal cycling stability after 150 cycles. Microstructural observations show that the domain structure of the DCP single crystals exhibits “staggered domain walls, inhomogeneous domain size, variety of domain structure,” while the relatively homogeneous stripe-like domains were observed in the ACP single crystals. After thermal cycling, new fine striped domains appear in both the DCP and ACP single crystals due to the instability of rotated polarization, but the piezoelectric and dielectric properties are not greatly affected. This work provides an intensive understanding of the effects of thermal cycling on the domain structure, which is useful for applications.
Optimal design of fast adiabatic topological pumping in modulated lattices
Authors: Ding Xianggui , Du Zongliang , Luo Jiachen , Chen Hui , Guan Zhenqun , Guo Xu
Published: April 2024

Utilizing synthetic dimensions generated by spatial or temporal modulation, topological pumping enables the exploration of higher-dimensional topological phenomena through lower-dimensional physical systems. In this Letter, we propose a rational design paradigm of fast adiabatic topological pumping based on 1D and 2D time-modulated discrete elastic lattices. First, the realization of topological pumping is ensured by introducing quantitative indicators to drive a transition of the edge or corner state in the lattice spectrum. Meanwhile, with the help of limiting speed for adiabaticity to calculate the modulation time, a mathematical formulation of designing topological pumping with the fastest modulation speed is presented. By applying the proposed design paradigm, topological edge–bulk–edge and corner–bulk–corner energy transport are achieved with 11.2 and 4.0 times of improvement in modulation speed compared to classical pumping systems in the literature. In addition, applying to 1D and 2D space-modulated systems, the optimized modulation schemes can reduce the number of stacks to 5.3% and 26.8% of the classical systems while ensuring highly concentrated energy transport. This design paradigm is expected to be extended to the rational design of fast topological pumping in other physical fields.
Design of a hemispherical shell shaped natural ventilation temperature observation instrument
Authors: Ma Zilan , Yang Jie , Jiang Lixia , Liu Qingquan , Ding Renhui
Published: April 2024

Atmospheric temperature is fundamental information for various industries, such as production, life, and scientific research. The temperature error induced by the solar rays can reach 1 °C or even higher. A hemispherical shell-shaped atmospheric temperature measuring instrument that can reduce heat pollution and increase air velocity was designed. First, the instrument was optimized using computational fluid dynamics (CFD) software packages. Then, the CFD software packages were employed to quantify the temperature errors of the instrument with varying situations. A neural network model was employed to develop a temperature error correction model that can be targeted for multi-variable changes. This model provides accurate correction data when the influencing factors change continuously. Finally, field experiments were performed. The experimental data analysis indicates that the mean temperature error and the maximum error of the instrument before correction are 0.08 and 0.25 °C, respectively. The root mean square error, the mean absolute error, and the correlation coefficient between measured temperature errors from experiments and corrected temperature errors from the correction model are 0.099, 0.016, and 0.952 °C, respectively. By utilizing a temperature error correction model, the measuring error of the instrument can be minimized to a range between −0.05 and 0.04 °C. Consequently, the instrument is anticipated to enhance temperature measurement accuracy to ∼0.1 °C.
Nonlinear binary indium-tin-oxide terahertz emitters with complete phase and amplitude control
Authors: Feng Xi , Zhang Xueqian , Qiu Haidi , Xu Quan , Zhang Weili , Han Jiaguang
Published: April 2024

Terahertz (THz) waves have demonstrated immense potential for various applications in multiple fields. To enable the development of compact THz applications, it is crucial to integrate THz emission and wavefront manipulation into a single device. This study proposes and experiments with a nonlinear binary THz emitter that utilizes a patterned indium-tin-oxide (ITO) film. By precisely controlling the displacements and area sizes of the composed ITO patches, we are able to fully and independently manipulate the phase and amplitude of the locally emitted THz wave at the +1st-order diffraction, so as to the corresponding wavefront. Our innovative approach provides a promising path toward miniaturized and functioning THz devices and systems.
Collective behaviors of animal groups may stem from visual lateralization—Tending to obtain information through one eye
Authors: Gao Jian , Gu Changgui , Long Yongshang , Zhang Xiyun , Shen Chuansheng , Yang Huijie
Published: April 2024

Animal groups exhibit various captivating movement patterns, which manifest as intricate interactions among group members. Several models have been proposed to elucidate collective behaviors in animal groups. These models achieve a certain degree of efficacy; however, inconsistent experimental findings suggest insufficient accuracy. Experiments have shown that some organisms employ a single information channel and visual lateralization to glean knowledge from other individuals in collective movements. In this study, we consider individuals’ visual lateralization and a single information channel and develop a self-propelled particle model to describe the collective behavior of large groups. The results suggest that homogeneous visual lateralization gives the group a strong sense of cohesiveness, thereby enabling diverse collective behaviors. As the overlapping field grows, the cohesiveness gradually dissipates. Inconsistent visual lateralization among group members can reduce the cohesiveness of the group, and when there is a high degree of heterogeneity in visual lateralization, the group loses their cohesiveness. This study also examines the influence of visual lateralization heterogeneity on specific formations, and the results indicate that the directional migration formation is responsive to such heterogeneity. We propose an information network to portray the transmission of information within groups, which explains the cohesiveness of groups and the sensitivity of the directional migration formation.
Nonlinear spreading behavior across multi-platform social media universe
Authors: Xia Chenkai , Johnson Neil F.
Published: April 2024

Understanding how harmful content (mis/disinformation, hate, etc.) manages to spread among online communities within and across social media platforms represents an urgent societal challenge. We develop a non-linear dynamical model for such viral spreading, which accounts for the fact that online communities dynamically interconnect across multiple social media platforms. Our mean-field theory (Effective Medium Theory) compares well to detailed numerical simulations and provides a specific analytic condition for the onset of outbreaks (i.e., system-wide spreading). Even if the infection rate is significantly lower than the recovery rate, it predicts system-wide spreading if online communities create links between them at high rates and the loss of such links (e.g., due to moderator pressure) is low. Policymakers should, therefore, account for these multi-community dynamics when shaping policies against system-wide spreading.
Theoretical model of femtosecond coherence spectroscopy of vibronic excitons in molecular aggregates
Authors: Rode Alexander J. , Arpin Paul C. , Turner Daniel B.
Published: April 2024

When used as pump pulses in transient absorption spectroscopy measurements, femtosecond laser pulses can produce oscillatory signals known as quantum beats. The quantum beats arise from coherent superpositions of the states of the sample and are best studied in the Fourier domain using Femtosecond Coherence Spectroscopy (FCS), which consists of one-dimensional amplitude and phase plots of a specified oscillation frequency as a function of the detection frequency. Prior works have shown ubiquitous amplitude nodes and π phase shifts in FCS from excited-state vibrational wavepackets in monomer samples. However, the FCS arising from vibronic-exciton states in molecular aggregates have not been studied theoretically. Here, we use a model of vibronic-exciton states in molecular dimers based on displaced harmonic oscillators to simulate FCS for dimers in two important cases. Simulations reveal distinct spectral signatures of excited-state vibronic-exciton coherences in molecular dimers that may be used to distinguish them from monomer vibrational coherences. A salient result is that, for certain relative orientations of the transition dipoles, the key resonance condition between the electronic coupling and the frequency of the vibrational mode may yield strong enhancement of the quantum-beat amplitude and, perhaps, also cause a significant decrease of the oscillation frequency to a value far lower than the vibrational frequency. Future studies using these results will lead to new insights into the excited-state coherences generated in photosynthetic pigment–protein complexes.
Revisiting lattice thermal conductivity of CsCl: The crucial role of quartic anharmonicity
Authors: Wang Xiaoying , Feng Minxuan , Xia Yi , Sun Jun , Ding Xiangdong , Li Baowen , Gao Zhibin
Published: April 2024

Thermal conductivity (κL) plays a critical role in thermal management applications. Usually, crystals with simpler structures exhibit higher κL due to fewer phonon scatterings. However, cesium chloride (CsCl) presents an anomaly, demonstrating an unexpectedly low κL of 1.0 W m−1 K−1 at 300 K, as observed in Professor Iversen's experimental measurement despite its simple structure. This prompts a need for understanding anomalous low κL and matching theory with experimental observations. Our study brings forth several findings for CsCl: (i) relying solely on three-phonon scattering inadequately captures κL. (ii) Anharmonic phonon renormalization significantly contributes to increased κL. (iii) Coherent phonons align temperature-dependent κL closely with the experiment. This work not only enhances understanding of anomalous κL in CsCl but also provides an approach to bridge the gap between experiment and theory in other crystals.
Role of partial stable stratification on fluid flow and heat transfer in rotating thermal convection
Authors: Barman Tirtharaj , Sahoo Swarandeep
Published: April 2024

The liquid iron core of the Earth undergoes vigorous convection driven by thermal and compositional buoyancy. The dynamics of convective fluid motions and heat transfer in such conditions are determined by background rotation, geometrical symmetry, and thermal interactions across the boundaries. In this study, rotating thermal convection in a horizontal fluid layer is considered to understand the fluid flow characteristics in the Earth's outer core focusing on the regions close to the rotational axis. The effects of a partial stable stratification on fluid flow and heat transfer are investigated to ascertain the physical significance of thermal core–mantle interaction on geomagnetic field generation driven by core fluid motion. It is found that even with non-linear evolution, convective instabilities retain the fundamental characteristics of linear onset modes. Mildly supercritical regimes lead to near laminar flows with the transition to turbulent convection occurring for strongly driven convection around 50–100 times enhanced buoyancy. Axial symmetry breaking and preferential damping of small-scale vortical structures are the hallmark of penetrative convection. Rapid rotation sustains small-scale helical flows in stable regions, a necessary ingredient for the sustenance of Earthlike dipolar magnetic fields. Coherent flow structures for strongly turbulent convection are obtained using reduced-order modeling. The overall total heat transfer is suppressed (up to 25%) due to the stable stratification although convective efficiency is enhanced (up to 30%) in the unstable regions favored by rapid rotation. Flow suppression is overcome under strong buoyancy forces, a relevant dynamical regime for deep-seated dynamo action in the Earth's core.
The effect of ligands on the size distribution of copper nanoclusters: Insights from molecular dynamics simulations
Authors: Elishav Oren , Blumer Ofir , Vanderlick T. Kyle , Hirshberg Barak
Published: April 2024

Controlling the size distribution in the nucleation of copper particles is crucial for achieving nanocrystals with desired physical and chemical properties. However, their synthesis involves a complex system of solvents, ligands, and copper precursors with intertwining effects on the size of the nanoclusters. We combine molecular dynamics simulations and density functional theory calculations to provide insights into the nucleation mechanism in the presence of a triphenyl phosphite ligand. We identify the crucial role of the strength of the metal–phosphine interaction in inhibiting the cluster’s growth. We demonstrate computationally several practical routes to fine-tune the interaction strength by modifying the side groups of the additive. Our work provides molecular insights into the complex nucleation process of protected copper nanocrystals, which can assist in controlling their size distribution and, eventually, their morphology.
Temperature-dependent anisotropy variation in quasi-two-dimensional ferromagnetic Cr5Te8
Authors: Wang Aina , Rahman Azizur , Du Zan , Liu Wei , Li Jingxin , Fan Jiyu , Ma Chunlan , Ge Min , Pi Li , Zhang Yuheng , Zhang Lei
Published: April 2024

The quasi-two-dimensional ferromagnet Cr5Te8 is a promising material for spintronic devices due to its near-room-temperature Curie temperature (TC), strong magnetic anisotropy, and easily controllable properties. In this study, the anisotropic magnetization of trigonal (T-) Cr5Te8 single crystals is investigated. Our magnetization study reveals that a ferromagnetic transition occurs when the magnetic field is aligned parallel to the c-axis (H//c), while an antiferromagnetic transition appears for H//ab, with a strong perpendicular anisotropy in the ground state. However, electron spin resonance (ESR) spectroscopy indicates that the direction of the easy-axis changes from the c-axis to the ab-plane at TV∼ 190 K as the temperature increases. Furthermore, angle-dependent ESR spectra demonstrate a characteristic of two-dimensional magnetism in the bulk Cr5Te8 single crystal. It is suggested that the temperature-dependent variation in anisotropy is caused by changes in lattice structure through the tuning of the dominant direct-exchange between the intralayers and the super-exchange within the interlayers. The temperature- and field-dependent microwave responses of T-Cr5Te8 are advantageous for the application of this material as a microwave-based spintronic device.
Negatively charged boron-vacancy defect in hexagonal boron nitride nanoparticles
Authors: Alzahrani Yahya A. , Alkahtani Masfer
Published: April 2024

Fluorescent defects in two-dimensional (2D) hexagonal boron nitride (hBN) crystals have attracted a great potential in quantum information and sensing technologies. In particular, the negatively charged boron vacancy (VB−) center has shown spin-dependent fluorescence in 2D flakes or large hBN crystals, which can be manipulated at room temperature, enhancing the application scope of hBN in quantum technologies. In this work, we demonstrate the generation of this interesting spin defect in small hBN nanoparticles (NPs) with a size range of 10–50 nm. The obtained optical properties of the VB− showed a photostable photoluminescence peaked at 820 nm with a spin-lattice relaxation time (T1) of 17 μs and optically detected magneto resonance (ODMR) contrast of 10%. Achieving long T1 time and high ODMR contrast is crucial for effective quantum sensing using small hBN nanocrystals. The reported spin-optical properties of the generated VB− spin defect in hBN NPs are comparable to those created in bulk/flake hBN crystals. These results open the door for optimizing such spin-dependent defects in small hBN NPs for promising applications, especially in quantum sensing and biology.
Cocatalyst activity mapping for photocatalytic materials revealed by the pattern-illumination time-resolved phase microscopy
Authors: Egawa Yuta , Kawaguchi Kei , Pan Zhenhua , Katayama Kenji
Published: April 2024

Photocatalytic water-splitting represents a promising avenue for clean hydrogen production, necessitating an in-depth understanding of the photocatalytic reaction mechanism. The majority of the photocatalytic materials need cocatalysts to enhance the photo-oxidation or reduction reactions. However, the working mechanism, such as collecting charge carriers or reducing the reaction barrier, is not clear because they disperse inhomogeneously on a surface, and it is difficult to follow the local charge carrier behavior. This study employs the pattern-illumination time-resolved phase microscopy (PI-PM) method to unravel the spatial charge carrier behavior in photocatalytic systems, utilizing time-resolved microscopic image (refractive index change) sequences and their clustering analyses. This approach is robust for studying the change in local charge carrier behavior. We studied two major cocatalyst effects on photocatalysts: TiO2 with/without Pt and hematite with/without CoPi. The PI-PM method, supported by charge type clustering and the effects of scavengers, allowed for the analysis of local activity influenced by cocatalysts. This approach revealed that the introduction of cocatalysts alters the local distribution of charge carrier behavior and significantly impacts their decay rates. In TiO2 systems, the presence of Pt cocatalysts led to a local electron site on the micron scale, extending the lifetime to a few tens of microseconds from a few microseconds. Similarly, in hematite films with CoPi, we observed a notable accumulation of holes at cocatalyst sites, emphasizing the role of cocatalysts in enhancing photocatalytic efficiency. The study's findings highlight the complexity of charge carrier dynamics in photocatalytic processes and the significant influence of cocatalysts.
Tunable bandpass filters using a defective phononic crystal shunted to synthetic negative capacitance for longitudinal waves
Authors: Jo Soo-Ho , Park Moonsu , Kim Minseo , Yang Jeonggyu
Published: April 2024

This study illustrates the successful achievement of tunable defect bands in one-dimensional defective phononic crystals (PnCs) through the incorporation of piezoelectric defects with synthetic negative capacitances (SNCs) for the first time. The efficacy of SNCs in creating tunable bandpass filters across a broad frequency range is thoroughly examined using the proposed analytical and numerical models. A newly developed electroelastically coupled transfer matrix that incorporates SNCs is presented, considering either series or parallel connection between bimorph piezoelectric elements. Defect band and transmittance analyses are conducted using the transfer matrix and S-parameter methods. Two key findings emerge from this investigation. First, when the total equivalent capacitance of the bimorph piezoelectric elements and SNC becomes zero, the defect band representing the point-symmetric defect-mode shape can be customized throughout the entire phononic bandgap. Second, the constant transmittance value, resembling short-circuit conditions, highlights the remarkable ability of SNCs to tune defect bands without energy dissipation, paving the way for fully tunable bandpass filters. To propel this research forward, future investigations could explore expanding the design space with double defects, adopting enhanced modeling techniques to account for lateral and shear effects, developing a control algorithm for the automatic optimization of SNC values in actively tunable bandpass filters, and incorporating artificial intelligence into design methods for piezoelectric defects with electrical connections.
Structural evolution and bonding properties of Nb1–2Gen−/0 (n = 3–7) clusters: Anion photoelectron spectroscopy and theoretical calculations
Authors: Lu Sheng-Jie , Gao Zhao-Ou
Published: April 2024

This study presents a collaborative experimental and theoretical investigation into the structures and electronic properties of niobium-doped germanium clusters. Anion photoelectron spectra for Nb1–2Gen− (n = 3–7) clusters were acquired using 266 nm photon energies, enabling the determination of adiabatic detachment energies and vertical detachment energies. In conjunction with these experimental measurements, density functional theory (DFT) calculations were conducted to validate the experimentally obtained electron detachment energies and elucidate the geometric and electronic structures of each anionic cluster. The agreement between DFT calculations and experimental data establishes a solid foundation for assessing the structural evolution and electronic properties of niobium-doped germanium clusters. It is noted that both neutral and anionic clusters exhibit predominantly similar overall structural characteristics, with the exception of Nb2Ge6− and Nb2Ge6. Furthermore, this investigation emphasizes the exceptional chemical stability of the D3d symmetric chair-shaped structure in Nb2Ge6−, providing insights into its bonding characteristics.
Direct laser patterning of ruthenium below the optical diffraction limit
Authors: Cruciani Lorenzo , Vreugdenhil Marnix , van Vliet Stefan , Abram Ester , van Oosten Dries , Bliem Roland , van Druten Klaasjan , Planken Paul
Published: April 2024

We describe a method that can be used to produce ruthenium/ruthenium oxide patterns starting from a ruthenium thin film. The method is based on highly localized oxidation of a small surface area of a ruthenium film by means of exposure to a pulsed laser under ambient conditions. Laser exposure is followed by dissolution of the un-exposed ruthenium in a NaClO solution, which leaves the conductive, partially oxidized ruthenium area on the substrate. Spatially selective oxidation, material removal, and, by implication, patterning, are, therefore, achieved without the need for a photoresist layer. Varying the exposure laser parameters, such as fluence, focus diameter, and repetition rate, allows us to optimize the process. In particular, it enables us to obtain circular Ru/RuO2 islands with a sub-diffraction-limited diameter of about 500 nm, for laser exposure times as short as 50 ms. The capability to obtain such small islands suggests that heat-diffusion is not a limiting factor to pattern Ru by laser heating on a (sub-)micron scale. In fact, heat diffusion helps in that it limits the area where a sufficiently high temperature is reached and maintained for a sufficiently long time for oxidation to occur. Our method provides an easy way to produce metallic Ru/RuO2 (sub-)micron structures and has possible applications in semiconductor manufacturing.
The determination of WSe2/GaN heterojunction band offsets in the semipolar (11–22) and nonpolar (11–20) planes by x-ray photoelectron spectroscopy
Authors: Wei Wanting , Zhao Guijuan , Lv Xiurui , Wang Xingliang , Liu Guipeng
Published: April 2024

Wurtzite structured GaN has a severe polarization effect in the c (0001) plane, compared to which the polarization effect is small in the semipolar (11–22) plane, and there is no polarization effect in the nonpolar (11–20) plane GaN. To investigate the influence of the polarization effect on the band bending at the heterojunction interface, we fabricated tungsten diselenide (WSe2)/(0001) GaN, WSe2/(11–22) GaN, and WSe2/(11–20) GaN heterojunctions. We measured the heterojunction valence band offsets (VBOs) by x-ray photoelectron spectroscopy. The VBOs of the three WSe2/GaN heterojunctions were measured to be 2.43 ± 0.15, 2.51 ± 0.15, and 2.23 ± 0.15 eV, and the conduction band offsets were calculated to be 1.11 ± 0.15, 1.19 ± 0.15, and 0.91 ± 0.15 eV, showing the type II energy band alignment of the three heterojunctions. The results demonstrate that WSe2/(11–22) GaN-faced heterojunction band bending is the largest. This provides theoretical insights for two-dimensional WSe2 and three-dimensional semipolar (11–22) GaN and nonpolar (11–20) GaN heterojunction device preparation.