bluuebunny/crossref_metadata_2025 huggingface dataset:
Full interferometric map of the L1157 southern outflow: Formamide (NH2CHO) can form in the gas, after all
Authors: López-Sepulcre A. , Codella C. , Ceccarelli C. , Podio L. , Robuschi J.
Published: November 2024

Context. The formation mechanism of interstellar formamide (NH2CHO), a key prebiotic precursor, is currently a matter of hot debate within the astrochemistry community, with both gas-phase and grain-surface chemical pathways having been proposed as its dominant formation route.

Aims. The aim of the present study is to place firm observational constraints on the formation pathways leading to formamide thanks to new interferometric observations of the molecular outflow driven by the protostellar binary L1157.

Methods. We employed the IRAM NOEMA interferometer to map the entire southern outflow of L1157, which contains three main shocked regions with increasing post-shock age: B0, B1, and B2. This allowed us to measure how the abundance of formamide, that of acetaldehyde (CH3CHO), and the ratio of the two, vary with time in this region. In order to gain a greater understanding of the most likely formation routes of formamide, we ran a grid of astrochemical models and compared these to our observations.

Results. A comparison between observations and astrochemical modelling indicates that there are two possible scenarios: one in which the amount of formamide observed can be explained by gas-phase-only chemistry, and more specifically via the reaction H2CO + NH2 → NH2CHO + H2 , and another in which part of the observed formamide originates from surface chemistry and part from gas-phase chemistry. Surface chemistry alone cannot account for the abundance of formamide that we measure.

Conclusions. While grain-surface chemistry cannot be ruled out, the present study brings definitive proof that gas-phase chemistry does work in L1157-B and acts efficiently in the production of this molecular species.
The effect of data-driving and relaxation models on magnetic flux rope evolution and stability
Authors: Wagner A. , Price D. J. , Bourgeois S. , Daei F. , Pomoell J. , Poedts S. , Kumari A. , Barata T. , Erdélyi R. , Kilpua E. K. J.
Published: November 2024

Context. Understanding the flux rope eruptivity and effects of data driving in modelling solar eruptions is crucial for correctly applying different models and interpreting their results.

Aims. We aim to investigate these by analysing the fully data-driven modelled eruption of the active regions (ARs) 12473 and AR11176, as well as preforming relaxation runs for AR12473 (found to be eruptive) where the driving is switched off systematically at different time steps. We intend to analyse the behaviour and evolution of fundamental quantities that are essential for understanding the eruptivity of magnetic flux ropes (MFRs).

Methods. The data-driven simulations were carried out with the time-dependent magnetofrictional model (TMFM) for AR12473 and AR11176. For the relaxation runs, we employed the magnetofrictional method (MFM) and a zero-beta magnetohydrodynamic (MHD) model to investigate how significant the differences between the two relaxation procedures are when started from the same initial conditions. In total, 22 simulations were studied. To determine the eruptivity of the MFRs, we calculated and analysed characteristic geometric properties such as the cross-section, MFR height, and physical stability parameters such as MFR twist and the decay index. Furthermore, for the eruptive cases, we investigated the effect of sustained driving beyond the point of eruptivity on the MFR properties and evolution.

Results. We find that the fully driven AR12473 MFR is eruptive, while the AR11176 MFR is not. For the relaxation runs, we find that the MFM MFRs are eruptive when the driving is stopped around the flare time or later, while the MHD MFRs show eruptive behaviour even if the driving is switched off one and a half days before the flare occurs. We also find that characteristic MFR properties can vary greatly even for the eruptive cases of different relaxation simulations.

Conclusions. The results suggest that data driving can significantly influence the evolution of the eruption, with differences appearing even when the relaxation time is set to later stages of the simulation when the MFRs have already entered an eruptive phase. Moreover, the relaxation model affects the results significantly, as highlighted by the differences between the MFM and MHD MFRs, showing that eruptivity in MHD does not directly translate to eruptivity in the MFM, despite the same initial conditions. Finally, if the exact critical values of instability parameters are unknown, tracking the evolution of typical MFR properties can be a powerful tool for determining MFR eruptivity.
CO-CAVITY project: Molecular gas and star formation in void galaxies
Authors: Rodríguez M. I. , Lisenfeld U. , Duarte Puertas S. , Espada D. , Domínguez-Gómez J. , Sánchez-Portal M. , Bongiovanni A. , Alcázar-Laynez M. , Argudo-Fernández M. , Bidaran B. , De Daniloff S. B. , Falcón-Barroso J. , Florido E. , García-Benito R. , Jimenez A. , Kreckel K. , Peletier R. F. , Pérez I. , Ruiz-Lara T. , Sánchez-Menguiano L. , Torres-Ríos G. , Villalba-González P. , Verley S. , Zurita A.
Published: November 2024

Context. Cosmic voids, distinguished by their low-density environment, provide a unique opportunity to explore the interplay between the cosmic environment and the processes of galaxy formation and evolution. Nevertheless, few data on the molecular gas have been obtained so far.

Aims. In this paper, we continue the research performed in the CO-CAVITY pilot project to study the molecular gas content and properties in void galaxies in order to search for possible differences compared to galaxies that inhabit denser structures.

Methods. We used the IRAM 30 m telescope to observe the CO(1–0) and CO(2–1) emission of 106 void galaxies selected from the CAVITY survey. Together with data from the literature, we obtained a sample of 200 void galaxies with CO data. We conducted a comprehensive comparison of the specific star formation rate (sSFR = SFR/M⋆), the molecular gas fraction (MH2/M⋆), and the star formation efficiency (SFE = SFR/MH2) between the void galaxies and a comparison sample of galaxies in filaments and walls selected from the xCOLD GASS survey.

Results. We find no statistically significant difference between void galaxies and a comparison sample in the molecular gas fraction as a function of stellar mass for galaxies on the star-forming main sequence (SFMS). However, for void galaxies, the SFE is found to be constant across all stellar mass bins, while there is a decreasing trend with M⋆, for the comparison sample. Finally, we find some indications for a smaller dynamical range in the molecular gas fraction as a function of distance to the SFMS in void galaxies.

Conclusions. Overall, we find that the molecular gas properties of void galaxies are not very different from those of denser environments. The physical origin of the most significant difference that we find – a constant SFE as a function of stellar mass in void galaxies – is unclear and further investigation and higher-resolution data are required to gain further insight.
X-Shooting ULLYSES: Massive stars at low metallicity
Authors: Backs F. , Brands S. A. , de Koter A. , Kaper L. , Vink J. S. , Puls J. , Sundqvist J. , Tramper F. , Sana H. , Bernini-Peron M. , Bestenlehner J. M. , Crowther P. A. , Hawcroft C. , Ignace R. , Kuiper R. , van Loon J. Th. , Mahy L. , Marcolino W. , Najarro F. , Oskinova L. M. , Pauli D. , Ramachandran V. , Sander A. A. C. , Verhamme O.
Published: November 2024

Context. Mass loss through a stellar wind is an important physical process that steers the evolution of massive stars and controls the properties of their end-of-life products, such as the supernova type and the mass of compact remnants. To probe its role in stellar evolution over cosmic time, mass loss needs to be studied as function of metallicity. For mass loss to be accurately quantified, the wind structure needs to be established jointly with the characteristics of small-scale inhomogeneities in the outflow, which are known as wind clumping.

Aims. We aim to improve empirical estimates of mass loss and wind clumping for hot main-sequence massive stars, study the dependence of both properties on the metal content, and compare the theoretical predictions of mass loss as a function of metallicity to our findings.

Methods. Using the model atmosphere code FASTWIND and the genetic algorithm fitting method KIWI-GA, we analyzed the optical and ultraviolet spectra of 13 O-type giant to supergiant stars in the Small Magellanic Cloud galaxy, which has a metallicity of approximately one-fifth of that of the Sun. We quantified the stellar global outflow properties, such as the mass-loss rate and terminal wind velocity, and the wind clumping properties. To probe the role of metallicity, our findings were compared to studies of Galactic and Large Magellanic Cloud samples that were analyzed with similar methods, including the description of clumping.

Results. We find significant variations in the wind clumping properties of the target stars, with clumping starting at flow velocities 0.01–0.23 of the terminal wind velocity and reaching clumping factors fcl = 2–30. In the luminosity (log L/L⊙ = 5.0–6.0) and metallicity (Z/Z⊙ = 0.2–1) range we considered, we find that the scaling of the mass loss M˙ with metallicity Z varies with luminosity. At log L/L⊙ = 5.75, we find M˙ ∝ Zm with m = 1.02 ± 0.30, in agreement with pioneering work in the field within the uncertainties. For lower luminosities, however, we obtain a significantly steeper scaling of m > 2.

Conclusions. The monotonically decreasing m(L) behavior adds a complexity to the functional description of the mass-loss rate of hot massive stars. Although the trend is present in the predictions, it is much weaker than we found here. However, the luminosity range for which m is significantly larger than previously assumed (at log L/L⊙ ≲ 5.4) is still poorly explored, and more studies are needed to thoroughly map the empirical behavior, in particular, at Galactic metallicity.
Language and design evolution of the OpenMC Monte Carlo particle transport code
Authors: Romano Paul , Tramm John , Shriwise Patrick
Published: November 2024

The OpenMC Monte Carlo particle transport code has been continuously developed for 13 years by a large community of contributors. In that time span, the codebase has undergone significant changes that have redefined what OpenMC is and made it an enduring presence in the nuclear science and engineering community. In this paper, we discuss the evolution of programming language use in OpenMC, trends in the overall design of the programming interfaces, and implications for the future of the code.
Treatment of Cancer-Associated Thrombosis: An Update
Authors: Voigtlaender Minna , Rolling Christina , Hart Christina
Published: November 2024

Patients with cancer are at increased risk of venous thromboembolism (VTE). Treatment of VTE remains challenging due to a significant risk of both VTE recurrence and bleeding compared with patients without underlying malignancy. Moreover, patients with cancer often present with several comorbidities such as tumor- or treatment-induced bone marrow failure, renal impairment, and extensive concomitant anticancer or supportive medication, resulting in potential drug–drug interactions. Further challenging circumstances include gastrointestinal (GI) disorders, in the context of a GI intraluminal tumor itself, GI surgery, or systemic therapy-induced GI toxicity. However, treatment options and study data in the management of cancer-associated thrombosis (CAT) have expanded over the last few years. As a result, it is becoming increasingly important to assess the patient's individual risk of bleeding and its comorbidities, and the patient's personal preferences. Prospectively, further therapeutic strategies such as factor XIa inhibitors are under clinical investigation. The aim of our narrative review is to summarize the current literature on therapy options for CAT, including common treatment situations encountered in the management of patients with cancer.
Unplanned 180-day Readmissions and Health Care Utilization after Immediate Breast Reconstruction for Breast Cancer
Authors: Rios-Diaz Arturo J. , Habarth-Morales Theodore E. , Isch Emily L. , Amro Chris , Davis Harrison D. , Broach Robyn B. , Jenkins Matthew , Fischer John P. , Serletti Joseph M.
Published: November 2024

Background To assess the burden of postdischarge health care utilization given by readmissions beyond 30 days following immediate breast reconstruction (IBR) nationwide.

Methods Women with breast cancer who underwent mastectomy and concurrent IBR (autologous and implant-based) were identified within the 2010 to 2019 Nationwide Readmission Database. Cox proportional hazards and generalized linear regression controlling for patient- and hospital-level confounders were used to determine factors associated with 180-day unplanned readmissions and incremental hospital costs, respectively.

Results Within 180 days, 10.7% of 100,942 women were readmitted following IBR. Readmissions tended to be publicly insured (30.8 vs. 21.7%, p < 0.001) and multimorbid (Elixhauser Comorbidity Index > 2 31.6 vs. 19.6%, p < 0.001) compared with nonreadmitted patients. There were no differences in readmission rates among types of IBR (tissue expander 11.2%, implant 10.7%, autologous 10.8%; p > 0.69). Of all readmissions, 40% occurred within 30 days and 21.7% in a different hospital and 40% required a major procedure in the operating room. Infection was the leading cause of readmissions (29.8%). In risk-adjusted analyses, patients with carcinoma in situ, publicly insured, low socioeconomic status, and higher comorbidity burden were associated with increased readmissions (all p < 0.05). Readmissions resulted in additional $8,971.78 (95% confidence interval: $8,537.72–9,405.84, p < 0.001) in hospital costs, which accounted for 15% of the total cost of IBR nationwide.

Conclusion The majority of inpatient health care utilization given by readmissions following mastectomy and IBR occurs beyond the 30-day benchmark. There is evidence of fragmentation of care as a quarter of readmissions occur in a different hospital and over one-third require major procedures. Mitigating postoperative infectious complications could result in the highest reduction of readmissions.
Wilson Disease: Novel Diagnostic and Therapeutic Approaches
Authors: Mariño Zoe , Schilsky Michael L.
Published: November 2024

The Wilson disease (WD) research field is rapidly evolving, and new diagnostic and therapeutical approaches are expected to be change-gamers in the disease for the incoming years, after decades of slow changing options. Non–ceruloplasmin-bound copper assays for circulating bioavailable copper are being tested for use in monitoring therapy and may also help in the diagnosis of new cases of WD. Other diagnostic advances include the use of quantitative detection of ATP7B peptides in dried blood spots, a method that is being tested for use in the newborn screening for WD, and the use of metallothionein immunostaining of liver biopsy specimens to differentiate WD from other liver diseases. Ongoing and future trials of gene therapy and use of methanobactin are expected to restore biliary copper excretion from the liver, thus making a cure for WD a plausible therapeutic objective. With the aim of helping updating physicians, this review summarizes the novel methods for WD diagnosis and future therapies. Advancing understanding of the scientific advances that can be applied to WD will be critical for ensuring that our patients will receive the best current and future care.
The Effect of Ambient Artificial Intelligence Notes on Provider Burnout
Authors: MIsurac Jason , Knake Lindsey A , Blum James M
Published: November 2024

Background: Healthcare provider burnout is a critical issue with significant implications for individual well-being, patient care, and healthcare system efficiency. Addressing burnout is essential for improving both provider well-being and the quality of patient care. Ambient artificial intelligence (AI) offers a novel approach to mitigating burnout by reducing the documentation burden through advanced speech recognition and natural language processing technologies that summarize the patient encounter into a clinical note to be reviewed by clinicians.

Objective: To assess provider burnout and professional fulfilment associated with Ambient AI technology during a pilot study, assessed using the Stanford Professional Fulfillment Index (PFI).

Methods: A pre-post observational study was conducted at University of Iowa Health Care with 38 volunteer physicians and advanced practice providers. Participants used a commercial ambient AI tool, over a 5-week trial in ambulatory environments. The AI tool transcribed patient-clinician conversations and generated preliminary clinical notes for review and entry into the electronic medical record. Burnout and professional fulfillment were assessed using the Stanford PFI at baseline and post-intervention.
Results: Pre-test and post-test surveys were completed by 35/38 participants (92% survey completion rate). Results showed a significant reduction in burnout scores, with the median burnout score improving from 4.16 to 3.16 (p=0.005), with validated Stanford PFI cutoff for overall burnout 3.33. Burnout rates decreased from 69% to 43%. There was a notable improvement in interpersonal disengagement scores (3.6 vs. 2.5, p<0.001), although work exhaustion scores did not significantly change. Professional fulfillment showed a modest, non-significant upward trend (6.1 vs. 6.5, p=0.10).

Conclusions: Ambient AI significantly reduces healthcare provider burnout and may enhance professional fulfillment. By alleviating documentation burdens, ambient AI can improve operational efficiency and provider well-being. These findings suggest that broader implementation of ambient AI could be a strategic intervention to combat burnout in healthcare settings.
The Synthesis and F-18 Labeling of a Cinacalcet Analogue Based on α-(Monofluoromethyl)arylmethylamine Structure
Authors: Liu Jianbo , Lai Yongxing , Qian Jiasheng , He Xingjin , Zhang Xiangsong
Published: November 2024

The fluorine-containing drug Cinacalcet is the only oral calcimimetic agent for the management of hyperparathyroidism in China and targets calcium sensitive receptor (CaSR) in organ tissues. The monofluoromethyl (CH2F) motif, found in many drug molecules and bioactive molecules, is particularly valuable as the CH2F functional group can mimic the methyl (CH3) motif frequently encountered in bioactive molecules. Replacing CH3 group of Cinacalcet with CH2F group will both bring new opportunities for the development of Cinacalcet generic drugs and provide a new option for the F-18 labeling synthesis of Cinacalcet. A Cinacalcet analogue has been successfully synthesized using commercial 2-amino-2-(naphthalen-1-yl)ethan-1-ol and 3-(3-(trifluoromethyl)phenyl)propanal as raw materials in a total yield of 24% in five steps and achieved the F-18 labeling synthesis of this analogue. This strategy is simple and efficient, paving the way for PET imaging of CaSR related diseases and inspiring development of new drugs based on Cinacalcet­.
Management of Ovarian Cysts through Individualized Homoeopathic Medicine: A Case Series
Authors: Rath Padmalaya , Wadhwa Bharti , Saraswat Kruiti , Singh Anamika
Published: November 2024

Ovarian cysts are common gynecological problems encountered by gynecologists in their day-to-day practice. They are benign growths arising from the ovary and occur in the reproductive age group. Conventional system of medicine usually opts for surgical procedures in such cases. Homoeopathic system of medicine is a specialized system that believes in individualization. This article reports five cases of suffering from ovarian cysts, who reported at Dr. D.P. Rastogi Central Research Institute, Noida, Uttar Pradesh, India. All the five cases were treated successfully with individualized homoeopathic medicines. Each patient received individualized homoeopathic medicine selected on the basis of the totality of symptoms using synthesis repertory with the help of RADAR software. Pre and post treatment ultrasongraphy USG reports were kept as evidence. The assessment of causal attribution of homeopathic treatment effect was performed using the Modified Naranjo Criteria for Homeopathy (MONARCH). Marked improvement was observed in all five cases, with complete resolution of the cysts along with symptomatic relief, which was evident by USG reports. The MONARCH scores were +9/13, +7/13, +8/13, +9/13, and +7/13, which indicate a positive causal attribution of homeopathy in relieving the symptoms. This case series suggests a significant role of individualized homeopathic medicines in the resolution of ovarian cysts and associated symptoms. The results obtained from this case series are encouraging.
Deep Learning-Based Pulmonary Nodule Screening: A Narrative Review
Authors: Mahajan Abhishek , Agarwal Ujjwal , Agrawal Rajat , Venkatesh Aditi , Shukla Shreya , Bharadwaj K S. S. , Apparao M L. V. , Pawar Vivek , Poonia Vivek
Published: November 2024

Given its capacity to generate three-dimensional pictures, computed tomography is the most effective means of detecting lung nodules with more excellent resolution of detected nodules. Small lung nodules can easily be overlooked on chest X-rays, making interpretation difficult. Artificial intelligence algorithms have recently demonstrated remarkable progress in medical imaging, especially with deep learning techniques such as convolutional neural networks (CNNs). CNN produces excellent results in natural image recognition and classification using abundant available data and the computational abilities of modern computers. It further reduces false-positive pulmonary nodules in medical image processing. This review article provides a detailed and inclusive review of recent advances, challenges, performance comparisons, and possible future directions for the problem of pulmonary nodule screening using deep learning methods.
Intraoperative Invasive Coronary Angiography after Coronary Artery Bypass Grafting
Authors: Berger Tim , Fagu Albi , Czerny Martin , Hartikainen Tau , Von Zur Mühlen Constantin , Kueri Sami , Eschenhagen Matthias , Kreibich Maximilian , Beyersdorf Friedhelm , Rylski Bartosz
Published: November 2024

Objective The aim of this study was to prospectively evaluate the feasibility and safety of intraoperative invasive coronary angiography (ICA) following coronary artery bypass grafting using a mobile angiography C-arm.

Methods Between August 2020 and December 2021, 18 patients were enrolled for intraoperative ICA following coronary artery bypass grafting. After skin closure, ICA was performed including angiography of all established bypass grafts via a mobile angiography system by an interventional cardiologist. Data on graft patency, stenosis, and kinking were assessed. Grafts were rated on an ordinal scale ranging from very poor (1) to excellent (5). Furthermore, the impact of ICA compared with flow measurement was assessed using the ordinal Likert scale ranging from (I) worse to (V) much better.

Results The ICA was considered better (V) compared with transient flow measurement in 38 (93%) and comparable (III) in 3 (7%) distal anastomoses. ICA impacted clinical or surgical decision-making in three patients (17%). In one patient, dual antiplatelet therapy for 6 months was initiated and rethoracotomy was needed in two (11%) patients with bypass graft revision and additional bypass grafting for graft occlusion. There were no cerebral and distal embolic events or access vessel complications observed and no postoperative acute kidney injury occurred.

Conclusion Intraoperative angiography after coronary bypass grafting is safe. Using a mobile angiographic device, graft patency, and function assessment was superior to transit time flow measurement leading to further consequences in a relevant number of patients. Therefore, it has the potential to reduce postoperative myocardial injury and improve survival.
Clinical, Laboratory, and Molecular Characteristics of Inherited Vitamin K–Dependent Coagulation Factors Deficiency
Authors: Perrone Salvatore , Raso Simona , Napolitano Mariasanta
Published: November 2024

Vitamin K–dependent coagulation factors deficiency (VKCFD) is a rare autosomal recessive genetic disease characterized by impaired levels of multiple coagulation factors (II, VII, IX, and X) and natural anticoagulants (proteins C and S). VKCFD is part of familial multiple coagulation factor deficiencies, reporting overall 50 affected families thus far. Disease manifestations are quite heterogeneous, bleeding symptoms may vary, and even, although generally mild, some patients may succumb to fatal outcomes. VKCFD diagnosis may be delayed because the disease phenotype simulates the most frequently acquired deficiencies of vitamin K. First-line coagulation assays, prothrombin time/international normalized ratio (PT/INR) and activated partial thromboplastin time (aPTT), are both prolonged; mixing test typically normalizes the clotting times; and vitamin K–dependent coagulation factors will be variably decreased. Molecularly, VKCFD is associated with mutations in γ-glutamyl-carboxylase (GGCX) or vitamin K epoxide reductase complex subunit 1 (VKORC1) genes. Vitamin K is involved not only in the biosynthesis of coagulation proteins but also in bone metabolism and cell proliferation. Therapeutic options are based on vitamin K supplementation, coagulation factors (prothrombin complex), and fresh frozen plasma, in case of severe bleeding episodes. Two case studies here illustrate the diagnostic challenges of VKCFD: case 1 depicts a woman with a history of bleeding episodes, diagnosed, only in her third decade of life with inherited homozygous GGCX gene mutation. Case 2 shows a man with an acquired vitamin K deficiency caused by Crohn's disease. Better understanding of GGCX and VKORC1 mutations aids in prognosis and treatment planning, with emerging insights suggesting potential limitations in the effectiveness of vitamin K supplementation in certain mutations.
Laboratory and Molecular Diagnosis of Factor XI Deficiency
Authors: Davidson Simon , Gomez Keith
Published: November 2024

The prevalence of factor XI (FXI) deficiency is 1 per 10 to 20,000 in the general population, much higher than that reported in most texts. The prevalence is higher in Ashkenazi Jews where it is about 1:20. Clinically, FXI deficiency presents as a mild bleeding disorder mostly associated with posttraumatic or postsurgical hemorrhages or unexplained minor bleeding. It is often discovered due to incidental finding of a prolonged activated partial thromboplastin time (aPTT) on routine laboratory screening. FXI deficiency is an autosomal recessive bleeding disorder with many causative F11 gene defects. Diagnosis is based on FXI activity, antigen levels, and molecular diagnostics. As FXI levels do not correlate with bleeding symptoms, identification of pathogenic genetic variants may be a more accurate predictor of bleeding risk and therefore aid in the clinical management of the patient. Two variants in the F11 gene account for most cases found in the Jewish and Arab populations. Patients with FXI deficiency can develop inhibitors to FXI although spontaneously acquired inhibitors are extremely rare. We will discuss laboratory and molecular assays used to diagnose FXI deficiency as well as interferences that can complicate diagnosis including new anticoagulants and acquired FXI inhibitors.
Research on design method of inertial interference self-compensating balance
Authors: Xu Bin , Yu Shien , Liu Long , Zhang Jianzhong
Published: November 2024

This paper proposes a design method for a wind tunnel balance that can compensate for inertial interference, aiming to address the issue of short effective time in pulse wind tunnels. This method also tackles the problem of the force measuring system’s inability to dampen quickly and the coupling of inertia vibration signals with the output signal of the balance, which affects aerodynamic measurement accuracy. The method calculates vibration displacement at specific positions of the balance structure using its acceleration, constructs compensation signals based on the relationship between these displacements and balance outputs, and then superimposes them onto the balance signal for compensation. The effectiveness of this compensation method is evaluated through finite element simulations and wind tunnel tests. The results demonstrate that by compensating for the balance signal, there is a significant reduction in the amplitude of the inertia vibration signal, leading to an enhancement in the repeatability accuracy of the measurement. This compensation method effectively solves under-compensation or over-compensation issues when accelerometers are placed on complex models with various modes, where obtaining accurate compensation signals becomes challenging. It provides a new technical approach to improve aerodynamic measurement accuracy by mitigating inertial interference during pulse wind tunnel testing.
Synthetic measurements of runaway electron synchrotron emission in the SPARC tokamak
Authors: Tinguely R. A. , Rosenthal A. M. , Silva Sa M. , Jean M. , Abramovic I.
Published: November 2024

With plasma currents up to 8.7 MA, the SPARC tokamak runs the risk of forming multi-MA beams of relativistic “runaway” electrons (REs), which could damage plasma facing components if unmitigated. The infrared (IR) and visible imaging and visible spectroscopy systems in SPARC are designed with measurements of synchrotron emission from REs in mind. Synchrotron radiation is emitted by REs along their direction of motion, opposite the plasma current. Matched clockwise and counterclockwise wide views are proposed to detect synchrotron and background radiation, allowing observation of RE synchrotron emission in both plasma current configurations. Due to SPARC’s high toroidal magnetic field strength, 12.2 T on axis, the synchrotron light spectrum is expected to peak in the visible-IR wavelength range. The synthetic diagnostic tool, Synchrotron Orbit-Following Toolkit, is used to model synchrotron images and spectra for three scenarios, with appropriate magnetic equilibria for each: REs generated during plasma current ramp-up, steady-state flat-top (although unlikely, but serving as a reference), and disruptions. Required time resolutions, achievable spatial coverage, and appropriate spectral ranges for various RE energies are assessed.
Broadband nonlinear Bragg diffraction from self-assembled structures in potassium tantalate niobate crystals
Authors: Wen Xing , Zhang Zijian , Wang Yu , Meng Xiangda , Jin Xinyu , Xing Bohan , Ruan Jinyu , Huang Xiaolin , Hu Chengpeng , Tan Peng , Tian Hao
Published: November 2024

Nonlinear optical process is a key technology to realize optical communication. Potassium tantalate niobate (KTa1−xNbxO3, KTN) crystals with large nonlinear optical coefficients are potential functional materials for realizing χ2 nonlinear optical processes. However, to accurately modulate the nonlinear optical signals of KTN crystals, the relationship between their second harmonic generation (SHG) properties and ferroelectric domain structures needs to be further investigated. Here, we report the special SHG processes generated by self-assembled structures in KTN crystals. Multimode quasi-phase matching and broadband nonlinear Bragg diffraction are achieved with the changing of polarizations and wavelengths of the fundamental wave. The physical processes behind the multi-polarization and multi-wavelength SHG properties of the KTN crystals are revealed. Our results about the multi-polarization and multi-wavelength SHG properties of KTN crystals will provide guidance for the design and realization of multimode nonlinear optical processes.
Optimizing laser-induced phase transformations in Sb2S3 thin films: Simulation framework and experiments
Authors: Resl J. , Hingerl K. , Gutierrez Y. , Losurdo M. , Cobet C.
Published: November 2024

We present a novel simulation approach combined with pulsed laser experiments, spectroscopic ellipsometry, and Raman spectroscopy to comprehensively analyze phase transformation dynamics in thin films. The simulations apply to any thin film stack and incorporate critical factors, such as thin film interference, heat transfer, and temperature-dependent optical properties during heating and melting. As a case study, we investigate the picosecond laser-induced amorphization of antimony sulfide (Sb2S3) thin films, a promising alternative to traditional phase-change materials in photonic applications to validate the simulation model. The computational efficiency of our simulations enables not only the investigation of the laser-induced phase transformation but also the optimization of key process parameters and parameter fitting. The simulations identified optimal film thickness and laser fluence parameters that maximize energy efficiency, melting effectiveness, and quenching rate while ensuring high reflectivity contrast between the amorphous and crystalline states. By constructing a wide-ranging, high-resolution parameter map of the laser fluence and film thickness dependence of the melting process, we demonstrate how this model guides the understanding of phase transformation dynamics. Raman spectroscopy confirms the polycrystalline to amorphous transition of Sb2S3 and provides a semiquantitative estimate of the amorphous fraction as a function of laser fluence, which is qualitatively consistent with the simulation predictions of the model. The open-source simulation framework, experimentally validated, provides valuable insights into laser-induced amorphization dynamics in Sb2S3 and related phase-change material thin films, enabling rapid optimization of photonic devices.
On the dual-phase-lag thermal response in the pulsed photoacoustic effect: A theoretical and experimental 1D-approach
Authors: Escamilla-Herrera L. F. , Derramadero-Domínguez J. M. , Medina-Cázares O. M. , Alba-Rosales J. E. , García-Rodríguez F. J. , Gutiérrez-Juárez G.
Published: November 2024

In a recent work, assuming a Beer–Lambert optical absorption and a Gaussian laser time profile, it was shown that the exact solutions for a 1D photoacoustic (PA) boundary-value-problem predict a null pressure for optically strong absorbent materials. In order to overcome this inconsistency, a heuristic correction was introduced by assuming that heat flux travels a characteristic length during the duration of the laser pulse [M. Ruiz-Veloz et al., J. Appl. Phys. 130, 025104 (2021)] τp. In this work, we obtained exact analytical solutions in the frequency domain for a 1D boundary-value-problem for the Dual-Phase-Lag (DPL) heat equation coupled with a 1D PA-boundary-value-problem via the acoustic wave equation. Temperature and pressure solutions were studied by assuming that the sample and its surroundings have a similar characteristic thermal lag response time τT; therefore, the whole system is assumed to have a similar thermal relaxation. A second assumption for τT is that it is considered as a free parameter that can be adjusted to reproduce experimental results. Solutions for temperature and pressure were obtained for a one-layer 1D system. It was found that for τT<τp, the DPL temperature has a similar thermal profile of the Fourier heat equation; however, when τT≥τp, this profile is very different from the Fourier case. Additionally, via a numerical Fourier transform, the wave-like behavior of DPL temperature is explored, and it was found that as τT increases, thermal wave amplitude is increasingly attenuated. Exact solutions for pressure were compared with experimental PA signals, showing a close resemblance between both data sets, particularly in time domain, for an appropriated value of τT; the transference function was also calculated, which allowed us to find the maximum response in frequency for the considered experimental setup.
Spectral density modulation and universal Markovian closure of fermionic environments
Authors: Ferracin Davide , Smirne Andrea , Huelga Susana F. , Plenio Martin B. , Tamascelli Dario
Published: November 2024

The combination of chain-mapping and tensor-network techniques provides a powerful tool for the numerically exact simulation of open quantum systems interacting with structured environments. However, these methods suffer from a quadratic scaling with the physical simulation time, and therefore, they become challenging in the presence of multiple environments. This is particularly true when fermionic environments, well-known to be highly correlated, are considered. In this work, we first illustrate how a thermo-chemical modulation of the spectral density allows replacing the original fermionic environments with equivalent, but simpler, ones. Moreover, we show how this procedure reduces the number of chains needed to model multiple environments. We then provide a derivation of the fermionic Markovian closure construction, consisting of a small collection of damped fermionic modes undergoing a Lindblad-type dynamics and mimicking a continuum of bath modes. We describe, in particular, how the use of the Markovian closure allows for a polynomial reduction of the time complexity of chain-mapping based algorithms when long-time dynamics are needed.
Effect of sweep angle on three-dimensional vortex dynamics over plunging wings
Authors: Cavanagh Alex , Bose Chandan , Ramesh Kiran
Published: November 2024

The effects of sweep angle and reduced frequency on the leading-edge vortex (LEV) structure over flapping swept wings in the Reynolds number (Re) range of O(104) are yet to be completely understood. With increasing interest in designing bio-inspired micro-air-vehicles, understanding LEV dynamics in such scenarios is imperative. This study investigates the effects of three different sweep angles (Λ=0°, 30°, and 60°) on LEV dynamics through high-fidelity improved delayed detached eddy simulation to analyze the underlying flow physics. Plunge ramp kinematics at two different reduced frequencies (k = 0.05 and 0.4) are studied to investigate the unsteady motion effects on LEV characteristics. The leading-edge suction parameter concept is applied to determine LEV initiation, and the results are verified against flow field visualization for swept-wing geometries. The force partitioning method is used to investigate the spanwise lift distribution resulting from the LEV. Distinct peaks in the lift coefficient occur for the high reduced frequency case due to the impulse-like plunging acceleration. This causes the LEV to detach from the leading edge more quickly and convect faster, significantly affecting the lift generated by the wing. As reduced frequency increases, the LEV breakdown mechanism switches from vortex bursting to LEV leg-induced instabilities. These results provide insights into the complex vortex structures surrounding swept wings at Re = 20 000, and the impact both sweep angle and reduced frequency have on the lift contribution of these flow features.
Ultrafast carrier dynamics and transient nonlinear absorption in chalcogenide perovskite BaZrS3
Authors: You Pengxian , Han Yadong , Yu Junhong , Yang Yunfan , Cao Yakun , Zhou Xiangyin , Qiao Liang , Hu Jianbo
Published: November 2024

The unique combination of excellent semiconducting properties in halide perovskites and the high stability and nontoxicity of oxide perovskites has led to a recent surge in interest in chalcogenide perovskite BaZrS3 for optoelectronic applications. However, to realize its potential in future device technologies, a comprehensive understanding of photoexcited carrier dynamics and transient optical response is imperative, yet it remains largely unexplored for BaZrS3. In this work, employing transient absorption spectroscopy, we have revealed that photoexcited carriers in epitaxial BaZrS3 nanofilms exhibit two exponential decay components relating to optical phonon cooling and interband recombinations. Meanwhile, our investigation unveils an intriguing transient nonlinear absorption phenomenon in BaZrS3, characterized by the ultrafast switching of the pump-induced transparency (i.e., the saturable absorption) to the absorption enhancement within a timescale commensurate with the measurement resolution (hundreds of femtosecond). This study provides crucial dynamic insights essential for leveraging chalcogenide perovskites, such as BaZrS3, in the development of advanced optoelectronic devices.
Rapid Mg substitution to Ga-sites and slow defect recovery revealed by depth-resolved photoluminescence in Mg/N-ion-implanted GaN
Authors: Kataoka Keita , Narita Tetsuo , Tomita Kazuyoshi , Yamada Shinji , Kachi Tetsu
Published: November 2024

Toward p-type GaN formation by Mg ion implantation (I/I) applicable to devices, depth-resolved photoluminescence (PL) revealed key behaviors during activation annealing for precise profile control, such as Mg substitution into Ga-sites (MgGa) and recovery of I/I defects. Depth profiles of the MgGa acceptor concentration were measured for Mg-I/I and Mg/N-I/I samples after ultra-high-pressure annealing at 1300 °C for 1–60 min. The cycle of low-damage dry etching and PL measurement was repeated over the I/I depth, and the MgGa concentration was estimated at each depth based on the calibration curve for the PL intensity ratio between acceptor-bound excitons (A0XA) and free excitons (FXA). In the region deeper than the I/I peak of 0.3 μm, almost all of the Mg atoms rapidly substituted into Ga-sites during the short annealing process. By contrast, the Mg substitution ratios in the shallower region were low when the annealing process was short but were improved by the sequential N-I/I. The low substitution ratio can be explained by MgGa bonding with nitrogen vacancy (VN)-related defects, while the implanted N-ions can compensate them. The PL intensity near the mean implantation depth of Mg/N-I/I was gradually improved as the annealing duration was increased to 60 min, indicating a slow reduction of nonradiative recombination centers. Simultaneously, the green luminescence associated with the VN-related defects decreased in intensity with increasing annealing time. Therefore, the main effect of prolonging annealing is the enhancement of slow defect recovery rather than enhancement of the Mg substitution as a fast process.
Insights into strain dependent lattice thermal conductivity of
α
- and
κ
-Ga2O3
Authors: Xiao Xinglin , Yuan Chao
Published: November 2024

α- and κ-Ga2O3 are promising candidates for high-performance devices such as high-power electronics, but the low thermal conductivity (TC) severely hinders its application. Strain inevitably exists in practical Ga2O3-based devices due to the mismatch of lattice structure and thermal expansion brought by heteroepitaxial growth, and it significantly influences the thermal properties of α- and κ-Ga2O3. By employing first-principles calculations and the phonon Boltzmann transport equation, we have studied the TC at the induced strain and optimized strain axis in free states and 16 different strain states. The TC at the induced strain and optimized strain axis generally decreases with increasing strain. Under −4% XZ-axes biaxial compressive strain, the kzz of α-Ga2O3 can increase to ∼1.7 times its original value, while under −2% XY-axes biaxial compressive strain, the kxx of κ-Ga2O3 can increase to 2.8 times its original value. The improvement of thermal transport properties is attributed to the increase in phonon group velocity and relaxation time caused by the phonon hardening and decrease in three-phonon scattering channels, respectively. However, we observed an exception: under +4% X-axis tensile strain, kyy of α-Ga2O3 increased by 1.1 times. Moreover, atomic bond analysis revealed that under XY-direction strain, the ICOHP values for α-Ga2O3 are −3.94 eV (at −4% strain), −3.76 eV (unstrained state), and −3.63 eV (+4% strain). This discovery elucidates the origin of phonon hardening under compressive strain, indicating that strengthened bonds enhance phonon transport. This study provides essential insights into the mechanisms of α- and κ-Ga2O3 TC under different strains.
Scaling transition of turbulent flame speed for thermodiffusively unstable flames
Authors: Troiani Guido , Lapenna Pasquale Eduardo , D'Alessio Francesco , Creta Francesco
Published: November 2024

This work presents an experimental set of Bunsen flames characterized by a moderate Reynolds number and a variable turbulence intensity. Ten lean hydrogen-enriched methane–air mixtures at three turbulence levels are investigated, ranging from methane–air to hydrogen–air mixtures. Such mixtures are selected to have an almost constant laminar flame speed while inducing the onset of thermal-diffusive (TD) instability by gradually increasing the hydrogen content of the blend. The flames' global consumption speed, stretch factor, and flame surface area are investigated and discussed as functions of the effective Lewis number of the mixture. As the interplay between TD instability and turbulence enhances the overall flame propagation, below a transitional Lewis number, flames are observed to be particularly sensitive to external turbulent forcing. This synergistic interaction is discussed in terms of Karlovitz and Lewis numbers. A parameterization of the turbulent flame speed is thus proposed, based on a functional form depending, concurrently, on both Karlovitz and Lewis numbers. The proposed form is shown to fit the experimental results at different turbulence levels and to capture the flame speed enhancement across the transitional Lewis number.
Trimerization-induced zone-folded phonons in 1T′-TaTe2
Authors: Zhang Yong , Zhang Heng , Qiu Tianyu , Zhang Yiying , Zhang Chong , Zhu Tongshuai , Zhong Zhicheng , Fei Fucong , Xi Xiaoxiang , Song Fengqi , Wang Xuefeng
Published: November 2024

The trimerized state is an intriguing structure in the superlattice with three unit cells distorted periodically. Here, we report on two kinds of featured phonon modes induced by the trimerization transition in 1T′-TaTe2. One is the almost temperature-independent zone-folded mode, stemming from the collective excitation due to the superlattice formation and the other is the normal mode with the step-like temperature-dependent intensity and frequency, which is the characteristic of the first-order transition of the trimerization. Furthermore, the trimerization can be totally suppressed when Mo-dopant content is less than 6 at. %. Our work not only unveils the featured phonon modes in trimerized system but also provides a pathway to identify the multimerization transition in solids by Raman spectroscopy.