bluuebunny/crossref_metadata_2025 huggingface dataset:
A possibly solar metallicity atmosphere escaping from HAT-P-32b revealed by Hα and He absorption
Authors: Yan Dongdong , Guo Jianheng , Seon Kwang-il , López-Puertas Manuel , Czesla Stefan , Lampón Manuel
Published: April 2024

This paper presents a hydrodynamic simulation that couples detailed non-local thermodynamic equilibrium (NLTE) calculations of the helium and hydrogen level populations to model the Hα and He 10830 transmission spectra of the hot Jupiter HAT-P-32b. A Monte Carlo simulation was applied to calculate the number of Lyα resonance scatterings, which is the main process for populating H(2). In the examined parameter space, only models with H/He ≥ 99.5/0.5, (0.5 ~ 3.0) times the fiducial value of FXUV, and spectral index βm = (0.16 ~ 0.3), can explain the Hα and He 10830 lines simultaneously. We found a mass-loss rate of ~(1.0 ~ 3.1) × 1013 g s−1, consistent with previous studies. Moreover, we found that the stellar Lyα flux should be as high as 4 × 105 erg cm−2 s−1, indicating high stellar activity during the observation epoch of the two absorption lines. Despite the fact that the metallicity in the lower atmosphere of HAT-P-32b may be super-solar, our simulations tentatively suggest it is close to solar in the upper atmosphere. Understanding the difference in metallicity between the lower and upper atmospheres is essential for future atmospheric characterisations.
A precise symbolic emulator of the linear matter power spectrum
Authors: Bartlett Deaglan J. , Kammerer Lukas , Kronberger Gabriel , Desmond Harry , Ferreira Pedro G. , Wandelt Benjamin D. , Burlacu Bogdan , Alonso David , Zennaro Matteo
Published: April 2024

Context.Computing the matter power spectrum,P(k), as a function of cosmological parameters can be prohibitively slow in cosmological analyses, hence emulating this calculation is desirable. Previous analytic approximations are insufficiently accurate for modern applications, so black-box, uninterpretable emulators are often used.

Aims.We aim to construct an efficient, differentiable, interpretable, symbolic emulator for the redshift zero linear matter power spectrum which achieves sub-percent level accuracy. We also wish to obtain a simple analytic expression to convertAstoσ8given the other cosmological parameters.

Methods.We utilise an efficient genetic programming based symbolic regression framework to explore the space of potential mathematical expressions which can approximate the power spectrum andσ8. We learn the ratio between an existing low-accuracy fitting function forP(k) and that obtained by solving the Boltzmann equations and thus still incorporate the physics which motivated this earlier approximation.

Results.We obtain an analytic approximation to the linear power spectrum with a root mean squared fractional error of 0.2% betweenk = 9 × 10−3 − 9 h Mpc−1and across a wide range of cosmological parameters, and we provide physical interpretations for various terms in the expression. Our analytic approximation is 950 times faster to evaluate thanCAMBand 36 times faster than the neural network based matter power spectrum emulatorBACCO. We also provide a simple analytic approximation forσ8with a similar accuracy, with a root mean squared fractional error of just 0.1% when evaluated across the same range of cosmologies. This function is easily invertible to obtainAsas a function ofσ8and the other cosmological parameters, if preferred.

Conclusions.It is possible to obtain symbolic approximations to a seemingly complex function at a precision required for current and future cosmological analyses without resorting to deep-learning techniques, thus avoiding their black-box nature and large number of parameters. Our emulator will be usable long after the codes on which numerical approximations are built become outdated.
Chromatically modeling the parsec-scale dusty structure in the center of NGC 1068
Authors: Leftley J. H. , Petrov R. , Moszczynski N. , Vermot P. , Hönig S. F. , Gamez Rosas V. , Isbell J. W. , Jaffe W. , Clénet Y. , Augereau J.-C. , Berio P. , Davies R. I. , Henning T. , Lagarde S. , Lopez B. , Matter A. , Meilland A. , Millour F. , Nesvadba N. , Shimizu T. T. , Sturm E. , Weigelt G.
Published: April 2024

Context. The Very Large Telescope Interferometer (VLTI) has been providing breakthrough images of the dust in the central parsecs of active galactic nuclei (AGNs), which is thought to be a key component of the AGN unification scheme and AGN host galaxy interaction. In single infrared bands, these images can enjoin multiple interpretations, some of which could challenge the unification scheme. This is the case for the archetypal type 2 AGN of NGC 1068, whereby the degeneracy is reduced by multi-band temperature maps that are hindered by an ambiguity in the alignment between different single-band images.

Aims. We aim to solve this problem by creating a chromatic model capable of simultaneously explaining the VLTI GRAVITY+MATISSE 2 μm–13 μm observations of AGNs hosted by NGC 1068.

Methods. We employed a simple disk and wind geometry populated by spherical black-body emitters and dust obscuration to create a versatile multi-wavelength modelling method for chromatic IR interferometric data of dusty objects.

Results. This simple geometry is capable of reproducing the spectro-interferometric data of NGC 1068 from the K through N bands. It explains the complex single band images with obscuration and inclination effects, and it solves the alignment problem between bands. We find that the resulting model disk and wind geometry is consistent with previous studies of comparable and larger scales. For example, compared to molecular gas emission, our model wind position angle (PA) of
2322°
is close to the mas-scale outflowing CO(6–5) PA of ∼33° seen with ALMA. The equivalent 90° offset model disk PA is also consistent with the CO(6–5) disk axis of 112° as well as the mas-scale disk axis from CO(2–1), CO(3–2), and HCO+(4–3) of 115 ± 5°. Furthermore, the resulting model images visually resemble the multiple achromatic image reconstructions of the same data when evaluated at the same wavelengths. We conclude that the IR emitting structure surrounding the AGN within NGC 1068 can indeed be explained by the clumpy disk+wind iteration of the AGN unification scheme. Within the scheme, we find that it is best explained as a type 2 AGN and the obscuring dust chemistry can be explained by a mix of olivine silicates and 16 ± 1% amorphous carbon.
Young stellar objects from the LAMOST and ZTF surveys: Physical properties, classification, and light curve analysis
Authors: Zhang J.-Y. , Zhang Y.-X. , Kang Z.-H. , Li C.-H. , Zhao Y.-H.
Published: April 2024

Context. The study of young stellar objects (YSOs) not only enhances our understanding of star formation and stellar evolution, but also contributes to broader areas of astrophysics, including planetary science, galactic dynamics, and astrochemistry.

Aims. We aimed to comprehensively analyse 657 YSOs and provide their physical parameter measurements using data from Zwicky Transient Facility (ZTF) g- and r-band light curves and the Gaia, WISE, 2MASS, and LAMOST databases. Specifically, we sought to identify periodicity in the light curves and classify the YSOs based on the Q – M variability plane, which enabled us to quantify flux asymmetry and quasi-periodicity.

Methods. To achieve our objectives, we conducted a meticulous examination of the light curves obtained from the ZTF and estimated the physical parameters of the YSOs. These parameters were discerned by integrating stellar model atmosphere grids, photometric data, Gaia DR3 parallaxes, and pre-main-sequence evolutionary tracks. We employed the Q – M variability plane to classify the YSOs and determine the presence of periodic patterns. Additionally, we analysed the distribution of variability slope angles in the colour-magnitude diagram (CMD) to discern patterns associated with extinction-driven and accretion-related variability.

Results. Our analysis revealed significant findings regarding the variability patterns and physical characteristics of the YSOs. Among the 657 objects analysed, 37 exhibited periodic variability and 2 displayed multi-period behaviour. Furthermore, we identified distinct variability patterns, including quasi-periodic symmetry, quasi-periodic dipping, aperiodic dipping, bursting behaviour, stochastic variability, and long-timescale variations. Notably, the distribution of variability slope angles in the CMD varied between dippers and bursters, indicating different underlying variability drivers. Additionally, we observed that YSOs classified as classical T Tauri stars and weak-line T Tauri stars exhibited contrasting light curve characteristics, with Class II YSOs displaying asymmetry and Class III YSOs showing (quasi-)periodic variations. These findings underscore the importance of considering variability patterns when classifying and determining the nature of YSOs.
Allocating the fixed cost as a complementary input in two-stage system: a DEA approach
Authors: Jin Xi , Li Feng , Xie Qiwei , Li Yongjun
Published: April 2024

The existing research on fixed cost allocation (FCA) in two-stage system data envelopment analysis (DEA) models typically regards the fixed cost as an additional input for each decision-making unit (DMU). However, these models overlook the prevalent real-world scenario where fixed costs act as complementary inputs in production processes. This study proposes a general two-stage network DEA model that incorporates the fixed cost as a complementary input to optimize the allocation scheme. First, we construct a functional relationship between the efficiency scores of DMUs and their allocated fixed costs using a modified super-efficiency DEA model, which effectively classifies DMUs and solves infeasible solutions within the variable returns to scale (VRS) framework. Then, we propose a fair and unique allocation model based on fairness and efficiency maximization principles. Specifically, we allocate fixed costs based on the operational scale for inelastic DMUs while equitably increasing the efficiency scores for elastic DMUs. Finally, a numerical example and an empirical study on subsidy allocation among 30 provinces demonstrate the rationality and acceptability of our approach.
Intravitreale Injektionen: Nachhaltigkeit durch Reduktion von Klinikabfall
Authors: Birtel Johannes , Hammer Maximilian , Feltgen Nicolas , Pauleikhoff Laurenz , Ong Ariel Yuhan , Geerling Gerd , Spitzer Martin S. , Charbel Issa Peter
Published: April 2024

Hintergrund Intravitreale Injektionen sind eine der häufigsten augenärztlichen Interventionen, mit geschätzt über 1 Mio. jährlichen Eingriffen in Deutschland. Ziel der Arbeit war eine Quantifizierung des Abfalls und des CO2-Fußabdrucks durch die Verwendung von Einmalinjektionssets sowie eine Evaluierung des möglichen Einsparpotenzials.

Material und Methoden Der Abfall und damit einhergehende CO2-Emissionen von standardmäßig verwendeten Einweginjektionssets wurde an operativen Zentren in Deutschland (n = 6) und Großbritannien (n = 2) untersucht. Intravitreale Injektionen mit minimiertem Materialverbrauch wurden evaluiert.

Ergebnisse Das Durchschnittsgewicht der Injektionssets und der hierdurch verursachte Müll betrug 165 g. Die Injektionssets bestanden durchschnittlich zu 145 g (88%) aus Plastik; 2,1 g (1,3%) aus Metall; 4,3 g (2,6%) aus Papier und 12,9 g (7,8%) aus Gaze/Tupfer. Bei 1 Mio. Injektionen entspricht dies 145,2 t Plastik, 2,1 t Metall, 4,3 t Papier und 12,9 t Gaze/Tupfer. Die Herstellung dieser Injektionssets entspricht extrapoliert einem CO2-Äquivalent von 752,6 t, die Verbrennung des entstehenden Mülls einem CO2-Äquivalent von 301,7 t. Mit einem materialsparenden Vorgehen kann der Injektionsset-assoziierte Abfall um 99% reduziert und Injektionen sicher durchgeführt werden.

Schlussfolgerung Die materiellen Ressourcen und die CO2-Emissionen von intravitrealen Injektionen können durch ressourcensparende Injektionen minimiert werden.
Kindliche Wunden versorgen
Authors: Kolbig Norbert
Published: April 2024

Glücklicherweise benötigen die meisten Wunden bei Kindern keine langwierige, aufwendige Versorgung. Hautverletzungen wie Schnitt-, Schürf- oder Platzwunden entstehen häufig beim kindlichen Spiel und heilen in der Regel komplikationslos ab. Dennoch gibt es auch bei Kindern Wunden, die eine moderne Versorgung mit spezifischen Auflagen benötigen. Zum Thema Wundversorgung wurde in den vergangenen Jahren viel geforscht. Basierend auf diesen Forschungsergebnissen wurden neue, innovative Wundauflagen entwickelt, die eine optimale Versorgung in jeder Wundheilungsphase ermöglichen. Von dieser Entwicklung profitieren auch Kinder, bei denen schwierige Wundverhältnisse vorliegen – wenngleich spezifische Forschung im Hinblick auf Kinder kaum vorhanden ist.
Augenbeteiligung bei ausgewählten rheumatischen Erkrankungen – Klinik im Erwachsenenalter
Authors: Baquet-Walscheid Karoline , Rath Thomas , Heiligenhaus Arnd
Published: April 2024

Okuläre Manifestationen rheumatischer Erkrankungen sind häufig und tragen wesentlich zur Morbidität und Reduktion der Lebensqualität der betroffenen Patienten bei. Die Kenntnis über typische Manifestationsformen ist bedeutsam für den Rheumatologen, um Patienten mit entsprechender Symptomatik frühzeitig ophthalmologisch vorstellen zu können oder auch regelmäßige Screeninguntersuchungen zu veranlassen (z. B. bei Behçet-Syndrom). Umgekehrt ist eine (ggf. auch dringliche) rheumatologische Mitbeurteilung bei bestimmten ophthalmologischen Krankheitsbildern entscheidend, um eine (u. U. letale) systemische assoziierte Erkrankung nicht zu übersehen. Patienten mit rheumatischen bzw. entzündlichen okulären Erkrankungen sollten immer durch den behandelnden Arzt über mögliche Symptome anderweitiger Organmanifestationen aufgeklärt werden, um eine verzögerte Diagnosestellung zu vermeiden. „Klassische“ Assoziationen für Uveitiden sind die (HLA-B27-assoziierten) Spondyloarthritiden und die
akute anteriore Uveitis sowie die retinale Vaskulitis mit oder ohne Panuveitis und das Behçet-Syndrom. Bei Patienten mit rheumatoider Arthritis oder ANCA-assoziierten Vaskulitiden hingegen treten typischerweise Skleritiden (mit oder ohne periphere ulzerative Keratitis) auf, aber auch eine Vielzahl weiterer Befunde ist möglich. Die enge interdisziplinäre Zusammenarbeit insbesondere in der Therapiegestaltung ist entscheidend, um eine gute Prognose für den Patienten zu sichern.
Correlation Between TRAb and Early Onset Hypothyroidism After
131I Treatment for Gravesʼ Disease
Authors: Song Qi , Fang Zhouyu , Wang Shurong , Liu Zhihua , Xiao Wenjin , Zong Haijun , Xie Ying
Published: April 2024

The aim of the study was to explore the clinical features related to early
hypothyroidism and the relationship between the changes of thyrotropin receptor
antibodies (TRAb) and early hypothyroidism in the course of 131I
treatment for Graves’ disease. This study was a retrospective observation,
including 226 patients who received the first 131I treatment. The
general information and laboratory tests were collected before and after
131I treatment, and the laboratory data affecting the difference
in disease outcome were analyzed. According to the changes of antibodies in the
third month, whether the changes of antibodies were involved in the occurrence
of early-onset hypothyroidism was analyzed. Early onset hypothyroidism occurred
in 165 of 226 patients, and the results showed that the incidence of early
hypothyroidism was higher in patients with low baseline TRAb level (p=0.03) and
increased TRAb after treatment (p=0.007). Both baseline TRAb levels (p<0.001)
and the 24-hour iodine uptake rate (p=0.004) are significant factors influencing
the changes in TRAb. The likelihood of a rise in TRAb was higher when the
baseline TRAb was less than 18.55 U/l and the 24-hour iodine uptake level
exceeded 63.61%. Low baseline and elevated post-treatment levels of TRAb were
significantly associated with early-onset hypothyroidism after 131I
treatment. Monitoring this index during RAI treatment is helpful in identifying
early-onset hypothyroidism and mastering the clinical outcome and prognosis of
Graves’ disease.
Diastereoselective Synthesis of NH-Unprotected Spiropyrrolidines via the Huisgen Reaction of Acenaphthoquinone-Derived Azomethine Ylides with β-Nitrostyrenes
Authors: Yavari Issa , Ghafouri Kiyana
Published: April 2024

4′-Nitro-2H-spiro[acenaphthylene-1,2′-pyrrolidine]-2-one derivatives are prepared via [3+2] cycloaddition reactions of azomethine ylides, generated in situ from acenaphthoquinone and primary amines, with β-nitrostyrenes in the presence of (
i
Pr)2NEt in methanol. Evidence for the structures of the products was obtained from single-crystal X-ray analysis. The important feature of this diastereoselective synthesis of NH-unprotected spiropyrrolidines is the formation of four contiguous stereogenic centers, one of which is quaternary, with high selectivity.
The Historical Evolvement of Movement and Exercise Training in Patients with Severe Burns and Their Potential Effects on Grafts, Scars, and Function
Authors: Kleinhapl Julia , Knappskog Kristine , Finnerty Celeste C. , Branski Ludwik , Suman Oscar E.
Published: April 2024

Exercise training for burn patients has become a major part of rehabilitation programs within the last decades. One of the main reasons for prolonged and long-term increased morbidity and mortality in this population is a persistent catabolic state with subsequent loss of lean body mass (LBM). A combination of resistance and aerobic exercises as well as stretching has shown to improve physical function by enhancing cardiopulmonary fitness, LBM, and strength and thus leading to ameliorated long-term outcomes of patients recovering from burns. In this literature review, we show an outline of the implementation of exercise training over the last decades into standardized care for patients with burns.
Learning about Literacy: Speech-Language Pathologists' Pre-Service and In-Service Training Experiences in the United States
Authors: Yi Julia J. , Erickson Karen A.
Published: April 2024

To better understand speech-language pathologists' (SLPs') pre-service and in-service training experiences in literacy and the relationship between their literacy training experiences and current practice, self-efficacy, and beliefs regarding their roles in literacy assessment and treatment, a web-based survey of SLPs was conducted (n = 444). Responses revealed that 60% of respondents completed at least one literacy course in their graduate programs: 55% took courses that embedded content in literacy assessment or treatment, and 23% took courses dedicated to literacy. These results varied based on the decade of graduation. Although 73.5% of respondents felt that their graduate programs trained them well or very well to assess and treat spoken language, only 8.5% felt the same about literacy. Most respondents (80%) reported completing in-service literacy training, and 89% reported wanting more literacy training. Completion of in-service training was positively, significantly related to respondents' current literacy-related clinical practice, self-efficacy, and beliefs regarding their roles; however, pre-service literacy training was not significantly related to any of these. Though in-service training appears to play a role in helping SLPs deliver literacy services, more emphasis on increasing the quantity and quality of pre-service and in-service training in the assessment and treatment of literacy is needed.
The Effect of Citizens’ Perception of Governance on Tax Compliance: A Cross-Country Analysis Study for 32 Sub-Saharan African Countries
Authors: Nichelatti Enrico , Hiilamo Heikki
Published: April 2024

Raising domestic revenue still represents a priority for most Sub-Saharan African countries that continue to face high tax non-compliance. This research investigates whether there is a link between citizens’ perceptions of governance and individual tax compliance in SSA. We employ a logistic regression model by applying five levels of specifications and using round 7 of the Afrobarometer, which contains information on Africans’ views on democracy, governance, economic reform, civil society, and quality of life for 32 countries. The main results suggest that perceptions of governance and attitudes towards tax compliance are positively associated, and their impact differs by country. The study proposes a binary mediation analysis to investigate the direct and indirect effects of governance perception on individual tax compliance, with trust in institutions serving as a mediator. Our findings suggest that a negative perception of governance may influence the trust in institutions and affect willingness to pay taxes.
Scintillation characteristics of the EJ-299-02H scintillator
Authors: Floyd N. , Hassan Md. T. , Tang Z. , Krivoš M. , Blatnik M. , Cude-Woods C. , Clayton S. M. , Holley A. T. , Ito T. M. , Johnson B. A. , Liu C.-Y. , Makela M. , Morris C. L. , Navazo A. S. C. , O’Shaughnessy C. M. , Renner E. L. , Pattie R. W. , Young A. R.
Published: April 2024

A study of the dead layer thickness and quenching factor of a plastic scintillator for use in ultracold neutron (UCN) experiments is described. Alpha spectroscopy was used to determine the thickness of a thin surface dead layer to be 630 ± 110 nm. The relative light outputs from the decay of 241Am and Compton scattering of electrons were used to extract Birks’ law coefficient, yielding a kB value of 0.087 ± 0.003 mm/MeV, consistent with some previous reports for other polystyrene-based scintillators. The results from these measurements are incorporated into the simulation to show that an energy threshold of (∼9 keV) can be achieved for the UCNProBe experiment. This low threshold enables high beta particle detection efficiency and the indirect measurement of UCN. The ability to make the scintillator deuterated, accompanied by its relatively thin dead layer, gives rise to unique applications in a wide range of UCN experiments, where it can be used to trap UCN and detect charged particles in situ.
DEFM: Delay-embedding-based forecast machine for time series forecasting by spatiotemporal information transformation
Authors: Peng Hao , Wang Wei , Chen Pei , Liu Rui
Published: April 2024

Making accurate forecasts for a complex system is a challenge in various practical applications. The major difficulty in solving such a problem concerns nonlinear spatiotemporal dynamics with time-varying characteristics. Takens’ delay embedding theory provides a way to transform high-dimensional spatial information into temporal information. In this work, by combining delay embedding theory and deep learning techniques, we propose a novel framework, delay-embedding-based forecast Machine (DEFM), to predict the future values of a target variable in a self-supervised and multistep-ahead manner based on high-dimensional observations. With a three-module spatiotemporal architecture, the DEFM leverages deep neural networks to effectively extract both the spatially and temporally associated information from the observed time series even with time-varying parameters or additive noise. The DEFM can accurately predict future information by transforming spatiotemporal information to the delay embeddings of a target variable. The efficacy and precision of the DEFM are substantiated through applications in three spatiotemporally chaotic systems: a 90-dimensional (90D) coupled Lorenz system, the Lorenz 96 system, and the Kuramoto–Sivashinsky equation with inhomogeneity. Additionally, the performance of the DEFM is evaluated on six real-world datasets spanning various fields. Comparative experiments with five prediction methods illustrate the superiority and robustness of the DEFM and show the great potential of the DEFM in temporal information mining and forecasting.
On α-z-Rényi divergence in the von Neumann algebra setting
Authors: Kato Shinya
Published: April 2024

We will investigate the α-z-Rényi divergence in the general von Neumann algebra setting based on Haagerup non-commutative Lp-spaces. In particular, we establish almost all its expected properties when 0 < α < 1 and some of them when α > 1. In an Appendix we also give an equality condition for generalized Hölder’s inequality in Haagerup non-commutative Lp-spaces.
Connecting exceptional orthogonal polynomials of different kind
Authors: Quesne C.
Published: April 2024

The known asymptotic relations interconnecting Jacobi, Laguerre, and Hermite classical orthogonal polynomials are generalized to the corresponding exceptional orthogonal polynomials of codimension m. It is proved that Xm-Laguerre exceptional orthogonal polynomials of type I, II, or III can be obtained as limits of Xm-Jacobi exceptional orthogonal polynomials of the same type. Similarly, Xm-Hermite exceptional orthogonal polynomials of type III can be derived from Xm-Jacobi or Xm-Laguerre ones. The quadratic transformations expressing Hermite classical orthogonal polynomials in terms of Laguerre ones is also extended to even X2m-Hermite exceptional orthogonal polynomials.
Characterizing the shear response of polymer-grafted nanoparticles
Authors: Moussavi Arman , Pal Subhadeep , Wu Zhenghao , Keten Sinan
Published: April 2024

Grafting polymer chains to the surface of nanoparticles overcomes the challenge of nanoparticle dispersion within nanocomposites and establishes high-volume fractions that are found to enable enhanced material mechanical properties. This study utilizes coarse-grained molecular dynamics simulations to quantify how the shear modulus of polymer-grafted nanoparticle (PGN) systems in their glassy state depends on parameters such as strain rate, nanoparticle size, grafting density, and chain length. The results are interpreted through further analysis of the dynamics of chain conformations and volume fraction arguments. The volume fraction of nanoparticles is found to be the most influential variable in deciding the shear modulus of PGN systems. A simple rule of mixture is utilized to express the monotonic dependence of shear modulus on the volume fraction of nanoparticles. Due to the reinforcing effect of nanoparticles, shortening the grafted chains results in a higher shear modulus in PGNs, which is not seen in linear systems. These results offer timely insight into calibrating molecular design parameters for achieving the desired mechanical properties in PGNs.
Oxide dissolution and oxygen diffusion scenarios in niobium and implications on the Bean–Livingston barrier in superconducting cavities
Authors: Lechner E. M. , Angle J. W. , Palczewski A. D. , Stevie F. A. , Kelley M. J. , Reece C. E.
Published: April 2024

We generalize a native Nb2O5 dissolution model [G. Ciovati, Appl. Phys. Lett. 89, 022507 (2006)] to sequential overlayer dissolutions, multilayer dissolution, and realistic temperature profiles, which may be applicable to other materials. The model is applied to secondary ion mass spectrometry depth profile measurements for varying temperature profiles and two-step oxide dissolution in Nb and found to agree well. In the context of the Meissner screening response due to impurity profiles on the length scale of the London penetration depth, the shallow diffusion of O impurities results in a substantial decrease in the peak supercurrent density near the surface. In this framework, oxide dissolution and oxygen diffusion can account for a rise in peak supportable magnetic field in SRF cavities with baking time and a suppression after the optimal baking time is reached, in good agreement with peak-field baking temperatures and times as well as recent quench field measurements.
Two-dimensional thin film lithium niobate photonic crystal waveguide for integrated photonic chips
Authors: Lu Jindong , Zhou Siyuan , Wu Yu , Yu Hua
Published: April 2024

The photonic crystal waveguide (PCW) possesses remarkable capabilities in manipulating light beams and light–matter interactions within the subwavelength range. This property renders it a highly promising structure for the miniaturization of optical devices. We delve into the mode characteristics in two-dimensional PCWs on thin film lithium niobate, establish the correlation between the single-mode region in the PCW and its photonic crystal duty cycle, and observe mode hybridization in the waveguide. A lithium niobate PCW with sidewall angles can realize single-mode transmission or mode conversion by adjusting the width of its defective waveguides, and it is theoretically and experimentally verified that a change in the width of the waveguide shifts the operating wavelength. The results of the mode analysis are useful in the design of waveguide structures for photonic crystal-based electro-optical modulators and optical sensors.
Structure and phase transitions in niobium and tantalum derived nanoscale transition metal perovskites, Ba(Ti,MV)O3, M=Nb,Ta
Authors: Lombardi Julien , Yang Long , Farahmand Nasim , Ruffino Anthony , Younes Ali , Spanier Jonathan E. , Billinge Simon J. L. , O’Brien Stephen
Published: April 2024

The prospect of creating ferroelectric or high permittivity nanomaterials provides motivation for investigating complex transition metal oxides of the form Ba(Ti, MV)O3, where M = Nb or Ta. Solid state processing typically produces mixtures of crystalline phases, rarely beyond minimally doped Nb/Ta. Using a modified sol-gel method, we prepared single phase nanocrystals of Ba(Ti, M)O3. Compositional and elemental analysis puts the empirical formulas close to BaTi0.5Nb0.5O3−δ and BaTi0.5Ta0.5O3−δ. For both materials, a reversible temperature dependent phase transition (non-centrosymmetric to symmetric) is observed in the Raman spectrum in the region 533–583 K (260–310 °C); for Ba(Ti, Nb)O3, the onset is at 543 K (270 °C); and for Ba(Ti, Ta)O3, the onset is at 533 K (260 °C), which are comparable with 390–393 K (117–120 °C) for bulk BaTiO3. The crystal structure was resolved by examination of the powder x-ray diffraction and atomic pair distribution function (PDF) analysis of synchrotron total scattering data. It was postulated whether the structure adopted at the nanoscale was single or double perovskite. Double perovskites (A2B′B″O6) are characterized by the type and extent of cation ordering, which gives rise to higher symmetry crystal structures. PDF analysis was used to examine all likely candidate structures and to look for evidence of higher symmetry. The feasible phase space that evolves includes the ordered double perovskite structure Ba2(Ti, MV)O6 (M = Nb, Ta) Fm-3m, a disordered cubic structure, as a suitable high temperature analog, Ba(Ti, MV)O3Pm-3m, and an orthorhombic Ba(Ti, MV)O3Amm2, a room temperature structure that presents an unusually high level of lattice displacement, possibly due to octahedral tilting, and indication of a highly polarized crystal.
Investigation of high field plasma dynamics in a laser-produced plasma expanding into a background gas
Authors: White Z. K. , Xu K. G. , Thakur S. Chakraborty
Published: April 2024

This paper presents an overview of experimental results of a laser-produced plasma expanding into a background gas, immersed within a large range of highly uniform magnetic fields (of up to 3 T), that are transverse to the expanding plasma. We used intensified gated imaging to capture the expansion of the plasma across and along the magnetic field lines to observe the spatiotemporal expansion dynamics for different magnetic field strengths. We observe changes in the perpendicular and parallel dynamics of the laser-produced plasmas expansion at high magnetic field. In addition, our results have also indicated the presence of electron-ion hybrid instabilities at relatively high pressures (100 mTorr) and relatively high magnetic field strengths (2 T), in accordance with theoretical calculations.
Controllable Si micro-structuring by temporally modulated single-shot femtosecond pulse lithography
Authors: Liu Yang , Huang Ji , Ye Yunxia , Liang Misheng , Dai Zijie , Zhang Jingjing , Wang Xuejiao , Tao Yufeng , Pan Changji
Published: April 2024

Micro-structured silicon surface plays a significant role in the electronics industry. Crystalline and amorphous phases of silicon, which have significantly different physical properties, can be transformed into each other using femtosecond laser, and assisted chemical etching enables the easy fabrication of various micro-structures. However, efficient and controllable fabrication of micro-cylinders, micro-rings, and micro-ring grooves on silicon surfaces still remains a challenge. Here, we propose a temporally modulated single-shot femtosecond pulse lithography technology, combining laser-induced silicon modification and chemical etching. In this technology, the occurrence of recrystallization allows for the flexible manipulation of the shape of the modified area, transitioning from circular to annular shapes by adjusting the laser fluence. This corresponds to the formation of micro-cylinders and micro-rings after etching. In the case of temporally shaped pulses, with an increasing pulse delay, the micro-rings formed after etching gradually transform into micro-ring grooves, as the recrystallization area created by the first sub-pulse is reacted by the second sub-pulse. Due to the characteristics of the single shot, the technology, when combined with the flying punch method, can be used for the high-efficiency fabrication of large-area silicon surface micro-structure arrays.
Fixed-time synchronization for two-dimensional coupled reaction–diffusion complex networks: Boundary conditions analysis
Authors: Wang Yishu , Lu Jianquan , Huang Tingwen , Cao Jinde , Zhong Jie
Published: April 2024

This paper examines fixed-time synchronization (FxTS) for two-dimensional coupled reaction–diffusion complex networks (CRDCNs) with impulses and delay. Utilizing the Lyapunov method, a FxTS criterion is established for impulsive delayed CRDCNs. Herein, impulses encompass both synchronizing and desynchronizing variants. Subsequently, by employing a Lyapunov–Krasovskii functional, two FxTS boundary controllers are formulated for CRDCNs with Neumann and mixed boundary condition, respectively. It is observed that vanishing Dirichlet boundary contributes to the synchronization of the CRDCNs. Furthermore, this study calculates the optimal constant for the Poincaré inequality in the square domain, which is instrumental in analyzing FxTS conditions for boundary controllers. Conclusive numerical examples underscore the efficacy of the proposed theoretical findings.
Seeing is believing: Correlating optoelectronic functionality with atomic scale imaging of single semiconductor nanocrystals
Authors: Ossia Yonatan , Levi Adar , Chefetz Nadav , Peleg Amir , Remennik Sergei , Vakahi Atzmon , Banin Uri
Published: April 2024

A unique on-chip method for the direct correlation of optical properties, with atomic-scale chemical–structural characteristics for a single quantum dot (QD), is developed and utilized in various examples. This is based on performing single QD optical characterization on a modified glass substrate, followed by the extraction of the relevant region of interest by focused-ion-beam–scanning electron microscope processing into a lamella for high resolution scanning transmission electron microscopy (STEM) characterization with atomic scale resolution. The direct correlation of the optical response under an electric field with STEM analysis of the same particle allows addressing several single particle phenomena: first, the direct correlation of single QD photoluminescence (PL) polarization and its response to the external field with the QD crystal lattice alignment, so far inferred indirectly; second, the identification of unique yet rare few-QD assemblies, correlated directly with their special spectroscopic optical characteristics, serving as a guide for future designed assemblies; and third, the study on the effect of metal island growth on the PL behavior of hybrid semiconductor–metal nanoparticles, with relevance for their possible functionality in photocatalysis. This work, therefore, establishes the use of the direct on-chip optical–structural correlation method for numerous scenarios and timely questions in the field of QD research.
Prediction challenge: First principles simulation of the ultrafast electron diffraction spectrum of cyclobutanone
Authors: Suchan Jiří , Liang Fangchun , Durden Andrew S. , Levine Benjamin G.
Published: April 2024

Computer simulation has long been an essential partner of ultrafast experiments, allowing the assignment of microscopic mechanistic detail to low-dimensional spectroscopic data. However, the ability of theory to make a priori predictions of ultrafast experimental results is relatively untested. Herein, as a part of a community challenge, we attempt to predict the signal of an upcoming ultrafast photochemical experiment using state-of-the-art theory in the context of preexisting experimental data. Specifically, we employ ab initio Ehrenfest with collapse to a block mixed quantum–classical simulations to describe the real-time evolution of the electrons and nuclei of cyclobutanone following excitation to the 3s Rydberg state. The gas-phase ultrafast electron diffraction (GUED) signal is simulated for direct comparison to an upcoming experiment at the Stanford Linear Accelerator Laboratory. Following initial ring-opening, dissociation via two distinct channels is observed: the C3 dissociation channel, producing cyclopropane and CO, and the C2 channel, producing CH2CO and C2H4. Direct calculations of the GUED signal indicate how the ring-opened intermediate, the C2 products, and the C3 products can be discriminated in the GUED signal. We also report an a priori analysis of anticipated errors in our predictions: without knowledge of the experimental result, which features of the spectrum do we feel confident we have predicted correctly, and which might we have wrong?
Experimental study on flow rate and pressure drop characteristics in T-junction pipes under rolling conditions
Authors: Wang Biaoxin , Su Bo , Zheng Wei , Ke Zhiwu , Lin Mei , Wang Qiuwang
Published: April 2024

Numerous T-junction circular channels are used in the pipeline system of marine dynamic platforms. Unlike terrestrial conditions, the fluid inside the channels experiences additional inertial forces due to rolling motion, leading to complex and variable fluid mixing characteristics within T-junction pipes. The flow and pressure drop characteristics were investigated inside the T-junction pipe under rolling motion conditions, including the average value, the fluctuation value, and the instantaneous value. The working fluid is considered as the de-ionized water. The inlet Reynolds number of the main pipe ranges from 2110 to 25 320, and the flow rate ratio is from 1 to 20. The rolling time and angle are 5–15 s and 0°–15°, respectively. The range of rolling Reynolds number is 0–3520. The results indicate that the influence of the rolling motion on the flow and pressure drop characteristics inside the T-junction pipe depends on the inertial force of the fluid itself. When the inertial force of the fluid itself is large, the influence of the rolling motion on the flow parameters will be weakened. The rolling motion has a greater impact on the branch than on the main pipe. Predictive relationships for flow rates and pressure loss coefficients are established under the stationary and rolling conditions, respectively, with a fitting error of less than 10%. In addition, the boundary that ignores the influence of rolling motion on flow fluctuations and the criteria for identifying fluid backflow are also proposed.
The universal two-fifths law of pier scour
Authors: Dey Subhasish , Ali Sk Zeeshan
Published: April 2024

Understanding scour at bridge piers is crucial for safeguarding public safety, ensuring infrastructure resilience, and planning effective maintenance. Despite over six decades of extensive studies aiming to develop predictive formulas for the equilibrium scour depth at bridge piers, more than 20 000 highway bridges in the United States have been spotted “scour critical.” The traditional reliance on existing empirical formulas has posed a severe challenge for researchers, hindering to achieve a unified relation for the equilibrium scour depth from a fundamental scientific tenet. This perspective article presents a breakthrough—a universal law governing the equilibrium scour depth at a circular pier embedded in a sediment bed, specifically in clear-water scour condition. Derived from a phenomenological model, the universal law reveals that the equilibrium scour depth to pier diameter ratio obeys a consistent two-fifths scaling law with the introduction of a newly coined pier-scour number. This number accounts for all the key parameters involved in a local scour phenomenon, including the approach mean flow velocity, threshold shear velocity for sediment grain motion, approach flow depth, pier diameter, and sediment grain size. Importantly, the scaling law contains an additional term involving the drag coefficient raised to the power of 2/5, addressing the impact of the pier shape on the equilibrium scour depth. The derived universal law undergoes the validation through an extensive dataset of experimental measurements on circular pier scour.
Thin film flow inside a uniformly heated/cooled inclined rotating cylinder
Authors: Kumawat Tara Chand
Published: April 2024

The present study investigates the flow of a thin film inside a uniformly heated/cooled cylinder rotating at various inclinations. The governing equations for mass, momentum, and energy are simplified using lubrication approximation and asymptotic analysis. The resulting spatiotemporal equation for film height evolution incorporates dimensionless parameters representing gravity, viscous drag, surface tension, and thermocapillary stress. Two-dimensional, steady-state solutions are derived, revealing that under the dominance of gravity over viscous drag, a liquid pool forms at the bottom of the horizontally rotating cylinder. This pool transforms into a more uniformly distributed thin film as the cylinder is rotated at slopes. Three-dimensional solutions show a ring structure for horizontally rotating cylinder, whereas it disappears for a cylinder rotating at slopes. Introducing infinitesimal axial perturbations to the steady solutions allows for the examination of their stability. The study finds that the thin film flow becomes unstable for a sloped cylinder. The gravitational force stabilizes (destabilizes) the flow for horizontal (vertical) cylinders. It is reported that thermocapillary stress has a stabilizing effect for a uniformly cooled cylinder. Additionally, the outcomes obtained through linear stability analysis have been corroborated through nonlinear computations.
Deep-learning reconstruction of complex dynamical networks from incomplete data
Authors: Ding Xiao , Kong Ling-Wei , Zhang Hai-Feng , Lai Ying-Cheng
Published: April 2024

Reconstructing complex networks and predicting the dynamics are particularly challenging in real-world applications because the available information and data are incomplete. We develop a unified collaborative deep-learning framework consisting of three modules: network inference, state estimation, and dynamical learning. The complete network structure is first inferred and the states of the unobserved nodes are estimated, based on which the dynamical learning module is activated to determine the dynamical evolution rules. An alternating parameter updating strategy is deployed to improve the inference and prediction accuracy. Our framework outperforms baseline methods for synthetic and empirical networks hosting a variety of dynamical processes. A reciprocity emerges between network inference and dynamical prediction: better inference of network structure improves the accuracy of dynamical prediction, and vice versa. We demonstrate the superior performance of our framework on an influenza dataset consisting of 37 US States and a PM2.5 dataset covering 184 cities in China.
Fluid structure interaction problem for flow past three unequal sized square cylinders at different Reynolds numbers
Authors: Manzoor Raheela , Ul-Islam Shams- , Jalil Maliha , Akhtar Yasmeen , Ahmed Ali , Kalsoom Shazia
Published: April 2024

The flow past three square cylinders of unequal size placed in an inline arrangement is studied using the lattice Boltzmann method at different Reynolds numbers [Re = (u∞ d)/ν] within the range of Re = 120, 150, 160, 175, and 200 for various gap spacings (g = s/d), ranging from 1 to 6. This study focused on the symmetric examination of flow behavior for various gap spacing within the three unequal-sized square cylinders. The main objective of this study was to investigate the effects of Reynolds numbers and gap spacing for flow structure mechanism and vortex shedding suppression in between the gap and down-stream position of all three cylinders. Results are obtained in terms of vorticity contours visualization, drag and lift coefficients, Strouhal number, and physical parameters. In vorticity contour visualization, different flow behaviors are observed, known as flow regimes, and are named according to their characteristics, and they are (i) steady flow regime, (ii) shear layer reattachment flow regime (SLR), (iii) fully developed vortex shedding flow regime, (iv) two-row fully developed vortex shedding flow regime, and (v) fully developed irregular vortex shedding flow regime. The present study also includes a discussion on aerodynamic forces, namely the mean drag coefficient (Cdmean), root mean square of the lift coefficient (Clrms), and Strouhal numbers (St) for three cylinders with sizes d = 20, d1 = 15, and d2 = 10, respectively. The maximum value of Cdmean for the first cylinder (C1) is obtained at (Re, g) = (200, 3) that is, 1.5156, where the existing flow regime is the SLR flow regime, while for C2 and C3, the maximum Cdmean values are examined at critical flow behaviors, where the existing flow regime is a fully developed irregular vortex shedding flow regime. Negative values of Cdmean are also examined for cylinders C2 and C3 at some combinations of (Re, g), attributed to the effect of thrust. Furthermore, it is noticed that the values of Strouhal number are increased with an increment in values of gap spacing. The highest value of the Strouhal number for all three cylinders is observed for C1 at (Re, g) = (120, 5), reaching 0.1556 along with a two-row fully developed flow regime. Furthermore, it is investigated from the present problem that the position of unequal sized square cylinders strongly influenced the flow structure mechanism. The information found and discussed in this study could be effective for structure designing arrangement in the case of three square cylinders of unequal size placed in a horizontal arrangement.
Optimization of a high through-flow design turbine using response surface method
Authors: Sun Yue , Cai Le , Chen Yingjie , Wang Songtao
Published: April 2024

Enhancing the through-flow capability of the turbine facilitates the potential to decrease the external dimension of the engine, leading to a reduction in weight and an increase in the thrust-to-weight ratio. The optimization of blade profile in terms of aerodynamic design is an essential strategy to improve the overall performance of the high through-flow design turbine. This study aims to develop an automated optimization technique, utilizing the response surface method (RSM), to enable reliable prediction and rapid optimization of aerodynamic performance. A parametric modeling method is devised to generate blade profiles with continuous curvature throughout the automated optimization process. The Box–Behnken experimental design, in combination with Reynolds-averaged Navier–Stokes numerical calculation, is employed to construct a second-order polynomial RSM approximation model. The optimization process comprises two levels: improving the through-flow capability and reducing blade profile loss. The optimized profile, Opt1, achieves a substantial 13.19% improvement in through-flow capability at the cost of a 12.27% increase in blade profile loss. Thus, further optimization is performed to minimize blade profile loss based on the Opt1 scheme. Geometric constraints are applied to the most influential parameters affecting through-flow capability to mitigate their impacts. Compared to the Opt1, the final optimized profile, Opt2, achieves a substantial 31.83% decrease in blade profile loss with a negligible sacrifice of 0.23% in through-flow capability.