bluuebunny/crossref_metadata_2025 huggingface dataset:
How to Approach the Difficult Perineum in Crohn's Disease
Authors: Rinebold Emily , Huang Alex L. , Hahn Sue J.
Published: May 2024

Crohn's disease (CD) is a chronic, inflammatory bowel disease with a wide range of presentations, including perianal disease. Presentation is variable, ranging from skin tags to complex fistulas, strictures, and nonhealing wounds. Symptoms of perianal CD can be devastating and may impact quality of life. Optimal management requires coordinated medical and surgical therapy. When possible, conservative treatment of perianal disease should be attempted. However, surgical treatment is often required, and some patients may ultimately require total proctocolectomy with permanent diversion due to the severity of disease. Even with close attention and treatment, disease can be recurrent, and complications of treatment are sometimes worse than the initial presentation. Novel treatments, including use of mesenchymal stem cells and autologous fat grafting, hold some promise, but are not yet widely available. Thorough knowledge of treatment options, careful patient selection, coordination between medical and surgical providers, and setting realistic expectations are important in the successful treatment of difficult perineal CD.
Neuromonitoring in a Case with Midbrain Cavernoma Operated in Sitting Position: Unveiling the Complexities
Authors: Rebello Joslita , Thakore Bhoomika
Published: May 2024

The sitting position is often utilized for mid-brain cavernoma excision due to its several surgical advantages. Intraoperative neuromonitoring aids dynamic functional assessment of neural structures in real-time. In this case report, we discuss the anesthetic management of a patient scheduled for midbrain cavernoma excision in a sitting position. Evoked potential monitoring was performed as the tumor was in proximity to cortico-spinal tracts. We used a combination of inhalational and intravenous anesthetics for the maintenance of anesthesia. Intraoperatively significant events included two episodes of venous air embolism, and loss of motor evoked potentials during the resection of the tumor. These complications were promptly recognized and managed. In the early postoperative period, the patient had motor power 3/5 in flexors of the right upper limb, which improved to normal by Day 5. Thus, good communication among anesthesiologists, neurologists, and surgeons helped identify altered evoked potential signals early, aiding the modification of dissection accordingly.
Management, Utilization, and Outcomes of Preterm Labor in an Integrated Health Care System
Authors: Getahun Darios , Sacks David A. , Shi Jiaxiao , Xie Fagen , Khadka Nehaa , Chiu Vicki Y. , Mensah Nana A. , Avila Chantal C. , Yeh Meiyu , Kawatkar Aniket A. , Ruma Michael S. , Joyce Derek , Fassett Michael J.
Published: May 2024

Objective Fetal fibronectin (fFN) testing and transvaginal ultrasound (TVUS) are diagnostic tools used to predict impending spontaneous preterm birth (sPTB) among women presenting with preterm labor (PTL). We evaluated the association between fFN testing or TVUS cervical length (CL) measurement in predicting sPTB, respiratory distress syndrome (RDS), neonatal intensive care unit (NICU) admission, and sPTB-related costs.

Study Design We conducted a retrospective cohort study using data from the Kaiser Permanente Southern California electronic health system (January 1, 2009–December 31, 2020) using diagnostic and procedure codes, along with a natural language processing algorithm to identify pregnancies with PTL evaluations. PTL evaluation was defined as having fFN and/or TVUS assessment. Outcomes were ascertained using diagnostic, procedural, and diagnosis-related group codes. Multivariable logistic regression assessed the association between fFN and/or TVUS results and perinatal outcomes.

Results Compared with those without PTL evaluations, those with positive fFN tests had higher adjusted odds ratio (adj.OR) for sPTB (2.95, 95% confidence interval [CI]: 2.64, 3.29), RDS (2.34, 95% CI: 2.03, 2.69), and NICU admission (2.24, 95% CI: 2.01, 2.50). In contrast, those who tested negative had lower odds for sPTB (adj.OR: 0.75, 95% CI: 0.70, 0.79), RDS (adj.OR: 0.67, 95% CI: 0.61, 0.73), and NICU admission (adj.OR: 0.74, 95% CI: 0.70, 0.79). Among those with positive fFN results, the odds of sPTB was inversely associated with CL. Health care costs for mothers and neonates were lowest for those with fFN testing only.

Conclusion This study demonstrates that positive fFN results were associated with an increased odds of sPTB, RDS, and NICU admission and the association with sPTB was inversely proportional to CL. Additionally, negative fFN results were associated with decreased odds of sPTB, RDS, and NICU admissions. fFN testing may predict these and other sPTB-related adverse outcomes hence its utility should be explored further. Moreover, fFN testing has some cost savings over TVUS.

Key Points
Is the Risk of Intrahepatic Cholestasis Increased with Supplemental Progesterone?
Authors: Rohn Matthew C.H. , Vignali Lindsey , Reeder Isabel , Khosravian Kiana , Petersen Scott
Published: May 2024

Objective This study aimed to evaluate the relationship between supplemental progesterone use during pregnancy and the development of intrahepatic cholestasis of pregnancy (ICP).

Study Design A retrospective, matched case–control study was conducted among a population of women who delivered at George Washington University Hospital (GW) between 2012 and 2022. Women diagnosed with ICP (cases) were identified using International Statistical Classification of Diseases (ICD) codes, and data were collected via chart abstraction. Descriptive data included patient demographics, pregnancy characteristics, and medical history. Laboratory values related to ICP were collected. Cases were matched on a 1:3 ratio by maternal age, body mass index, and gravidarum to women who delivered at GW during the same month and did not carry a diagnosis of ICP (controls). A univariate logistic regression model was created to assess the use of supplemental progesterone between groups, adjusting for the use of assisted reproductive technology in the current pregnancy, and a history of liver disease.

Results One hundred and twenty women who delivered during the study period were confirmed to have a diagnosis of ICP. Cases were matched with 360 controls and measures compared between the two groups. Cases were significantly more likely to have a history of liver disease (5.9 vs. 1.7%, p = 0.0021), multiple gestation (10.0 vs. 3.3%, p < 0.0001), a history of ICP in a previous pregnancy (10.0 vs. 0%, p < 0.0001), and to have delivered at an earlier gestational age (mean 37.1 vs. 38.6 weeks, p < 0.0001) as compared with controls. No differences were seen in the odds of supplemental progesterone use in both unadjusted and adjusted models (OR = 1.14, 95% CI: 0.30–4.34; adjusted Odds Ratio [aOR] = 0.98 [0.24–3.94]).

Conclusion Contrary to recent evidence, no association was seen with the use of supplemental progesterone. It is possible that the associated risk with supplemental progesterone is dependent on medication formulation or route of administration.

Key Points
Therapeutic Hypothermia for Neonatal Hypoxic–Ischemic Encephalopathy: Reducing Variability in Practice through a Collaborative Telemedicine Initiative
Authors: Leandro Danieli M.K. , Variane Gabriel F.T. , Dahlen Alex , Pietrobom Rafaela F.R. , de Castro Jessica A.R.R. , Rodrigues Daniela P. , Magalhães Mauricio , Mimica Marcelo J. , Van Meurs Krisa P. , Chock Valerie Y.
Published: May 2024

Objective This study aimed to assess the viability of implementing a tele-educational training program in neurocritical care for newborns diagnosed with hypoxic–ischemic encephalopathy (HIE) and treated with therapeutic hypothermia (TH), with the goal of reducing practice variation.

Study Design Prospective study including newborns with HIE treated with TH from 12 neonatal intensive care units in Brazil conducted from February 2021 to February 2022. An educational intervention consisting of 12 biweekly, 1-hour, live videoconferences was implemented during a 6-month period in all centers. Half of the centers had the assistance of a remote neuromonitoring team. The primary outcome was the rate of deviations from TH protocol, and it was evaluated during a 3-month period before and after the intervention. Logistic regression via generalized estimating equations was performed to compare the primary and secondary outcomes. Protocol deviations were defined as practices not in compliance with the TH protocol provided. A subanalysis evaluated the differences in protocol deviations and clinical variables between centers with and without neuromonitoring.

Results Sixty-six (39.5%) newborns with HIE were treated with TH during the preintervention period, 69 (41.3%) during the intervention period and 32 (19.1%) after intervention. There was not a significant reduction in protocol deviations between the pre- and postintervention periods (37.8 vs. 25%, p = 0.23); however, a decrease in the rates of missing Sarnat examinations within 6 hours after birth was seen between the preintervention (n = 5, 7.6%) and postintervention (n = 2, 6.3%) periods (adjusted odds ratio [aOR]: 0.36 [0.25–0.52], p < 0.001). Centers with remote neuromonitoring support had significantly lower rates of seizures (27.6 vs. 57.5%; aOR: 0.26 [0.12–0.55], p < 0.001) and significant less seizure medication (27.6 vs. 68.7%; aOR: 0.17 [0.07–0.4], p < 0.001).

Conclusion This study shows that implementing a tele-educational program in neonatal neurocritical care is feasible and may decrease variability in the delivery of care to patients with HIE treated with TH.

Key Points
The blocking and transmission effects of lower level system in patent transaction - evidence from Chinese colleges and universities
Authors: Junrong Zhang
Published: May 2024

Conflicts and contradictions within the legal system may affect the effectiveness of law enforcement, but scholars have not conducted sufficient empirical research on the mechanism. Based on three periods of mixed cross-sectional data in 2015 and 2019 when the reform of patent transaction system in colleges and universities, which represents a quasi-natural experiment, has been carried out, this study adopted a difference-in-difference (DID) model to empirically analyze the efficiency of patent transactions. It was found that if the lower level system was not removed or revised in time when the higher level law had been revised, it would have a blocking effect on the implementation of the higher level law and thus make patent transaction less efficient. Furthermore, when the lower level system was revised accordingly, it would have a transmission effect on the implementation of the higher level law, which could promote its implementation. This basic conclusion remains valid after a series of robustness tests and can provide useful lessons for the systemic revision and organizing of laws, as well as the reform of the economic and social systems.
New tools for treating chronic wounds
Authors: Shapiro Maura
Published: May 2024

Advances in electrical stimulation, cell and drug delivery systems, and 3D printing hold potential for chronic wound treatment.
Development and application of a three-dimensional pseudo-Voigt function for muon spin relaxation analysis of weakly magnetic materials
Authors: Umar M. D. , Hariyanto H. L. , Absor M. A. U.
Published: May 2024

We present a three-dimensional pseudo-Voigt function to analyze muon spin relaxation (μSR) in weakly magnetic materials. Our approach approximates the Voigt function by superimposing Gaussian and Lorentzian functions using a one-dimensional method proposed by Di Rocco and Cruzado [Acta Phys. Pol., A 122, 666 (2012)]. We derive the peak of the Voigt function analytically and express the Half Width at Half Maximum (HWHM) of the Voigt function as a function of the HWHMs of the Gaussian and Lorentzian functions. We compare the pseudo-Voigt function to the exact Voigt function and find a maximum normalized discrepancy of ∼20% at the tail of the distribution function, depending on the ratio of Lorentzian to Gaussian HWHMs and internal magnetic field. We apply the derived three-dimensional pseudo-Voigt function to calculate μSR functions for zero- and longitudinal-field experiments and use them to fit μSR time spectra of La2−xSrxCuO4 with 2.4% Sr, employing a strong collision model with the static-based pseudo-Voigt muon spin relaxation function as the initial condition. Our results show that the Gaussian- and Lorentzian-fitted parameters and fluctuation rate are in good agreement with results from the exact Voigt function for a temperature range of 30–200 K, with the deviation of Gaussian and Lorentzian width parameters reaching ∼0.15 G below 30 K.
A broadband pulse amplifier for Joule heating experiments in diamond anvil cells
Authors: Geballe Zachary M. , Lai Joseph , Walter Michael J.
Published: May 2024

Decades of measurements of the thermophysical properties of hot metals show that pulsed Joule heating is an effective method to heat solid and liquid metals that are chemically reactive or difficult to contain. To extend such measurements to hundreds of GPa pressure, pulsed heating methods have recently been integrated with diamond anvil cells. The recent design used a low-side switch and active electrical sensing equipment that was prone to damage and measurement error. Here, we report the design and characterization of new electronics that use a high-side switch and robust, passive electrical sensing equipment. The new pulse amplifier can heat ∼5 to 50 μm diameter metal wires to thousands of kelvin at tens to hundreds of GPa using diamond anvil cells. Pulse durations and peak currents can each be varied over three orders of magnitude, from 5 µs to 10 ms and from 0.2 to 200 A. The pulse amplifier is integrated with a current probe. Two voltage probes attached to the body of a diamond anvil cell are used to measure voltage in a four-point probe geometry. The accuracy of four-point probe resistance measurements for a dummy sample with 0.1 Ω resistance is typically better than 5% at all times from 2 µs to 10 ms after the beginning of the pulse.
Predict the prevalence and incidence of Parkinson’s disease using fractal interpolation-LSTM model
Authors: Dai Zhong , Liu Shutang , Liu Changan
Published: May 2024

The investigation of the prediction of disease population is a noticeable exploration topic in the field of sciences. As a type of neurological disease, the incidence and prevalence of Parkinson’s disease are still difficult to accurately study. In this paper, a method is proposed to forecast the number of incident cases (NumIn), incidence rate (InRa), the number of prevalent cases (NumPr), and prevalence rate (PrRa) of Parkinson’s disease in ten countries selected. Using past data on the incidence rate, the number of prevalent cases, and the prevalence rate from 1990 to 2019, three types of fractal interpolations with different fractal dimensions are constructed for reconstructing the past data, where the vertical scaling factors are determined by the method proposed in this article. Then, the Long Short-Term Memory (LSTM) model is employed to forecast the values of NumIn, InRa, NumPr, and PrRa with Parkinson’s disease in 2020. Meanwhile, the autoregressive integrated moving average model is used to predict the values compared with the LSTM model. The evaluation metrics employed for error calculation include the root mean square error and the coefficient of determination (R2). According to the proposed optimal criteria, the best predicted results are the average of three types of prediction values based on the LSTM model by analyzing and comparing eight predicted results.
On Derkachov–Manashov R-matrices for the principal series of unitary representations
Authors: Neretin Yury A.
Published: May 2024

In 2001–2013 Derkachov and Manashov with coauthors obtained simple and natural expressions of R-matrices for the principal series of representations of the groups SL(2,C), SL(2,R), SL(n,C), SO(1, n). The Yang–Baxter identities for these intertwining operators are kinds of multivariate hypergeometric transformations. Derivations of the identities are based on calculations “of physical level of rigor” with divergent integrals. Our purpose is a formal mathematical justification of these results.
Spatiotemporal patterns corresponding to phase synchronization and generalized synchronization states of thermoacoustic instability
Authors: Pawar Samadhan A. , Raghunath Midhun P. , K. Valappil Reeja , Krishnan Abin , Manoj Krishna , Sujith R. I.
Published: May 2024

Thermoacoustic instability in turbulent combustion systems emerges from the complex interplay among the flame, flow, and acoustic subsystems. While the onset of thermoacoustic instability exhibits a global order, the characteristics of local interactions between subsystems responsible for this order are not well understood. Here, we utilize the framework of synchronization to elucidate the spatiotemporal interactions among heat release rate fluctuations in the flame, velocity fluctuations in the flow, and acoustic pressure fluctuations in a turbulent combustor, across the bluff-body stabilized flame. We examine two forms of thermoacoustic instability, characterized by phase synchronization and generalized synchronization of the acoustic pressure and global heat release rate oscillations. Despite the presence of global synchrony, we uncover a coexistence of frequency synchrony and desynchrony in the local interaction of these oscillations within the reaction field. In regions of frequency-locked oscillations, various phase-locking patterns occur, including phase synchrony and partial phase synchrony. We observe that the local formation of small pockets of phase synchrony and strong amplitude correlation between these oscillations is sufficient to trigger the state of global phase synchronization. As the global dynamics approach generalized synchronization, these local regions of synchrony expand in the reaction field. Additionally, through coupled analysis of acoustic pressure and local flow velocity fluctuations, we infer that the spatial region of flow–acoustic synchrony plays a significant role in governing thermoacoustic instabilities. Our findings imply that, in turbulent combustors, an intrinsic local balance between order, partial order, and disorder within the coupled subsystems sustains the global order during thermoacoustic instability.
Status of h-BN quasi-bulk crystals and high efficiency neutron detectors
Authors: Alemoush Z. , Tingsuwatit A. , Maity A. , Li J. , Lin J. Y. , Jiang H. X.
Published: May 2024

III-nitrides have fomented a revolution in the lighting industry and are poised to make a huge impact in the field of power electronics. In the III-nitride family, the crystal growth and use of hexagonal BN (h-BN) as an ultrawide bandgap (UWBG) semiconductor are much less developed. Bulk crystals of h-BN produced by the high-temperature/high-pressure and the metal flux solution methods possess very high crystalline and optical qualities but are impractical to serve as substrates or for device implementation as their sizes are typically in millimeters. The development of crystal growth technologies for producing thick epitaxial films (or quasi-bulk or semi-bulk crystals) in large wafer sizes with high crystalline quality is a prerequisite for utilizing h-BN as an UWBG electronic material. Compared to traditional III-nitrides, BN has another unique application as solid-state neutron detectors, which however, also require the development of quasi-bulk crystals to provide high detection efficiencies because the theoretical efficiency (ηi) relates to the detector thickness (d) by ηi=1−e−dλ, where λ denotes the thermal neutron absorption length which is 47 μm (237 μm) for 10B-enriched (natural) h-BN. We provide an overview and recent progress toward the development of h-BN quasi-bulk crystals via hydride vapor phase epitaxy (HVPE) growth and the attainment of thermal neutron detectors based on 100 μm thick 10B-enriched h-BN with a record efficiency of 60%. The thermal neutron detection efficiency was shown to enhance at elevated temperatures. Benchmarking the crystalline and optical qualities of h-BN quasi-bulk crystals with the state-of-the-art mm-sized bulk crystal flakes and 0.5 μm thick epitaxial films identified that reducing the density of native defects such as vacancies remains the most critical task for h-BN quasi-bulk crystal growth by HVPE.
A neural network-based algorithm for the reconstruction and filtering of single particle trajectory in magnetic particle tracking
Authors: Prashanth Mohit , Du Pan , Wang Jian-xun , Wu Huixuan
Published: May 2024

Magnetic particle tracking (MPT) is a recently developed non-invasive measurement technique that has gained popularity for studying dense particulate or granular flows. This method involves tracking the trajectory of a magnetically labeled particle, the field of which is modeled as a dipole. The nature of this method allows it to be used in opaque environments, which can be highly beneficial for the measurement of dense particle dynamics. However, since the magnetic field of the particle used is weak, the signal-to-noise ratio is usually low. The noise from the measuring devices contaminates the reconstruction of the magnetic tracer’s trajectory. A filter is then needed to reduce the noise in the final trajectory results. In this work, we present a neural network-based framework for MPT trajectory reconstruction and filtering, which yields accurate results and operates at very high speed. The reconstruction derived from this framework is compared to the state-of-the-art extended Kalman filter-based reconstruction.
Computational analysis of the anode-directed streamers propagation in atmospheric pressure C4F7N/N2 mixtures
Authors: Levko Dmitry , Thiruppathiraj Sudharshanaraj , Raja Laxminarayan L.
Published: May 2024

In recent years, interest in synthetic C4F7N as a gas insulator has been growing due to its unique insulation properties and low global warming potential. In spite of this, very few studies are devoted to the analysis of the electric breakdown of C4F7N and its mixtures with other dilutants such as CO2 and N2. In the present paper, we use a two-dimensional fluid model to analyze the electrical breakdown of the atmospheric pressure C4F7N/N2 mixture. We establish the influence of the C4F7N fraction in the mixture and the cathode voltage rise rate on the breakdown voltage. We find that the ratio between the electron attachment frequency and the voltage rise rate defines the streamer parameters. Namely, if the time scale of electron attachment to C4F7N is much faster than the voltage rise rate, the plasma electronegativity of the streamer body and of its head is extremely high, and it is difficult to define exactly the streamer head location. In the opposite case of the fast rise rates, the conventional streamers with sharp heads were obtained.
High-Q silicon microring resonator with ultrathin sub-wavelength thicknesses for sensitive gas sensing
Authors: Guo Rongxiang , He Qi , Zhang Zunyue , Xu Yingqi , Zhang Shujiao , Lang Qiyue , Xiao Shuqi , Han Peize , Wang Jiaqi , Ding Tianben , Liu Tiegen , Tsang Hon Ki , Goda Keisuke , Cheng Zhenzhou
Published: May 2024

Microring resonators, due to their ability to enable robust strong light–matter interactions within their structures, have garnered substantial interest for their utility in sensing applications, particularly in the realm of gas detection. However, there is an inherent trade-off between a microring resonator's quality factor and confinement factor in the air, making it difficult to balance them. Here, we demonstrate a novel solution with a suspended nanomembrane silicon (SNS) microring resonator. This resonator has ultrathin sub-wavelength thicknesses (0.02–0.03λ), which breaks the trade-off, offering not only a high intrinsic quality factor of 6 × 105 but also an extraordinarily large confinement factor of ∼80% in the air at mid-infrared wavelengths. As a proof-of-concept demonstration, we applied the SNS microring resonator for CO2 gas sensing, exhibiting a sensitivity over 10 times higher than conventional silicon resonators and a large dynamic sensing range spanning from 0% to 100% with a high resolution of better than 4% and chemical specificity. By virtue of its excellent properties, the SNS microring resonator has the potential to open new possibilities for the development of unprecedented nanophotonic integrated circuits, with a broad range of applications in on-chip sensing scenarios.
Fluid simulations of resistive drift-wave turbulence with diamagnetic flow in ZPED experiments
Authors: Zhao H. J. , Mao Y. , Wang Z. Y. , Xiao W. W. , Xiao Y.
Published: May 2024

We derive a diamagnetic resistive fluid model (DRF) and develop an associated two-dimensional fluid simulation code (DRF-2D) to explore the dynamics of resistive drift modes within the plasmas of the Zheda Plasma Experiment Device (ZPED). The validation of the linear dispersion relation for the DRF-2D code revealed a harmonious agreement between analytical theory and linear numerical simulations. Leveraging plasma parameters obtained from the ZPED experiments, we conducted a comprehensive series of nonlinear simulations using the DRF-2D code. Our simulations successfully replicate the nonlinear trends in turbulent fluctuations and transport observed in the ZPED experiments, particularly demonstrating a remarkably accurate alignment of the turning point in the magnetic field. Notably, the DRF model sheds light on the observed frequency sign reversal from the electron diamagnetic direction to the ion diamagnetic direction in the ZPED experiments. This is demonstrated through well-matched turning points in the confining magnetic field between the nonlinear simulations and ZPED experiments. The fidelity of our model in capturing these phenomena underscores its efficacy in providing valuable insights and predictive capabilities for the intricate dynamics observed in the ZPED plasmas.
Effects of valence changes of iodine on perovskite (CH3NH3PbI3) Raman
Authors: Bai Rui , Xu Mei-Feng , Wang Su , Kuang Liao-Sha , Wang Chao-Nan , Jin Yong-Long , Xu Tian
Published: May 2024

In recent years, organic–inorganic hybrid perovskite materials have garnered extensive attention from scholars. Given its high absorption coefficient, carrier mobility, and diffusion length, it is widely studied for applications in various optoelectronic devices, such as solar cells, photodetectors, field-effect transistors, and light emitting diodes. Among them, the interfacial charge transfer process is a key factor influencing the performance of devices using perovskite materials. The charge transfer (CT) at the interface is typically detected via Raman spectroscopy. There are three types of related CT processes, namely, the interfacial ground state charge transfer, the photoinduced charge transfer resonance, and the electronic excitation resonance within the molecule itself. Among these factors, electronic excitation resonance manifests as an exciton resonance within the perovskite structure, providing energy for nearby charge transfer, thereby promoting charge transfer and enhancing Raman signals. Therefore, enhancing exciton resonance within the perovskite structure plays a crucial role in optoelectronic devices. This paper aimed to study the mechanism of oxygen plasma passivation of interstitial iodine defects and its enhancement effect on the Raman of perovskite substrates. Typically, interstitial iodine defects induce electron–hole recombination. In the process of oxygen plasma treatment, interstitial iodine is converted into pentavalent iodine, which can effectively fill related defects, inhibit electron–hole recombination, and prolong exciton lifetime, thereby promoting charge transfer and enhancing Raman intensity.
Computational study of a helium-propellant microwave electrothermal thruster
Authors: Lee Juyeon , Raja Laxminarayan L.
Published: May 2024

The microwave electrothermal thruster (MET) utilizes wave-exited microdischarges to heat gas flows, enhancing the specific impulse of the thruster. Our computational study investigates a 17.5 GHz helium-propellant MET, employing a two-dimensional, axisymmetric fluid model of plasma coupled with electromagnetic wave and gas flows. The discharges operate in the glow regime, remaining weakly ionized, and in thermal non-equilibrium. The plasma densities reach approximately 1020m−3, and the gas temperature is around 2000 K. Even a slight off-resonant frequency operation results in a significantly lower plasma density and gas temperature. Gas heating, primarily driven by electromagnetic Joule heating, plays a critical role in influencing the overall discharge behavior. The measured peak thrust and specific impulse are 8.24 mN and 292 s, respectively, at a mass flow rate of 3.2 mg/s with 30 W of power. Compared to a cold gas thruster, there is a significant increase in the specific impulse by a factor of approximately 1.7. The enhanced performance trades off with propulsive efficiency, which decreases by a factor of 1.5 from the peak 65% at 10 W. This is due to higher energy losses to cavity walls from heat conduction with increased power. These findings underscore the critical balance between the input power and mass flow rate to improve the MET performance, highlighting the importance of power management to maximize thrust and efficiency. Furthermore, the predicted thrust and specific impulse agree well with experimental values for nominally similar MET thruster studies in the literature.
Micro-macro consistency in multiscale modeling: Score-based model assisted sampling of fast/slow dynamical systems
Authors: Crabtree E. R. , Bello-Rivas J. M. , Kevrekidis I. G.
Published: May 2024

A valuable step in the modeling of multiscale dynamical systems in fields such as computational chemistry, biology, and materials science is the representative sampling of the phase space over long time scales of interest; this task is not, however, without challenges. For example, the long term behavior of a system with many degrees of freedom often cannot be efficiently computationally explored by direct dynamical simulation; such systems can often become trapped in local free energy minima. In the study of physics-based multi-time-scale dynamical systems, techniques have been developed for enhancing sampling in order to accelerate exploration beyond free energy barriers. On the other hand, in the field of machine learning (ML), a generic goal of generative models is to sample from a target density, after training on empirical samples from this density. Score-based generative models (SGMs) have demonstrated state-of-the-art capabilities in generating plausible data from target training distributions. Conditional implementations of such generative models have been shown to exhibit significant parallels with long-established—and physics-based—solutions to enhanced sampling. These physics-based methods can then be enhanced through coupling with the ML generative models, complementing the strengths and mitigating the weaknesses of each technique. In this work, we show that SGMs can be used in such a coupling framework to improve sampling in multiscale dynamical systems.
Demonstration of low-mode shape control in indirect-drive double shell implosions at the NIF
Authors: Mohamed Z. L. , Loomis E. N. , Robey H. F. , Goodarzi S. , Palaniyappan S. , Sacks R. , Sauppe J. P. , Sagert I. , Keiter P. A. , Schmidt D. W. , Donovan P. , Christiansen N. , Stark D. J. , Meyerhofer D. D. , Merritt E. C. , Montgomery D. S. , Xu H.
Published: May 2024

Double shell inertial confinement fusion is a concept for achieving robust thermonuclear burn that uses dense metal shells to compress deuterium-tritium (DT) fuel to fusion conditions. Double shell implosions are typically indirectly driven and involve a target that consists of a low-Z ablator, a foam layer, and a high-Z pusher surrounding the DT fuel. The goal of the campaign is to achieve a volumetric burn as radiation losses from the DT fuel are trapped by the opaque high-Z shell. The overall performance of double shell implosions relies on the efficient collisional transfer of kinetic energy between layers. The efficiency of this transfer (and therefore the overall performance of a given implosion) is degraded by the presence of low-mode asymmetries. P2 asymmetries are often observed in spatially resolved 2D radiographs of nominal double shell implosions. This work discusses three such experiments: one with an oblate P2 asymmetry, one with a prolate P2 asymmetry, and one with an approximate spherical symmetry. After performing a shape analysis of the oblate and prolate implosions to quantify asymmetries, these experimental results were compared with the results of hydrodynamic simulations for the two experiments. Differences between the experiment and simulation were then used to design an approximately spherical implosion by altering the incident laser cone fraction. Radiographs from the experiment that implemented the modified cone fraction show evidence of an implosion that is approximately spherical until bang time. This design is intended to serve as a point design for future studies that will seek to optimize various aspects of the double shell target.
Universal bounds for spreading on networks
Authors: Fibich Gadi , Levin Tomer
Published: May 2024

Spreading (diffusion) of innovations is a stochastic process on social networks. When the key driving mechanism is the peer effect (word of mouth), the rate at which the aggregate adoption level increases with time depends strongly on the network structure. In many applications, however, the network structure is unknown. To estimate the aggregate adoption level as a function of time for such innovations, we show that the minimal and maximal adoption levels are attained on a homogeneous two-node network and on a homogeneous infinite complete network, respectively. Solving the Bass model on these two networks yields explicit lower and upper bounds for the expected adoption level on any network. These bounds are tight, and they also hold for the individual adoption probabilities of nodes. The gap between the lower and upper bounds increases monotonically with the ratio of the rates of internal and external influences.
How does crosstalk influence the jitter of a clock signal?
Authors: Liao Shuang , Wang Houjun , Tong Yuchen , Chen Cheng , Tan Feng , Guo Lianping
Published: May 2024

The stability and accuracy of the clock signal are crucial for the proper operation of various electronic devices and systems, as they directly impact system performance. In high-speed electronic systems, the clock signal is susceptible to interference by crosstalk. Therefore, evaluating the performance of the clock signal under crosstalk disturbance is important. Jitter, commonly used as an indicator to assess the degree of this interference, plays a significant role in this evaluation. In this paper, a method is proposed for assessing crosstalk-induced jitter (CIJ) based on scattering parameters. To verify the effectiveness of the method, CIJ was measured for clock signals with frequencies of 25, 100, and 156.25 MHz. In addition, the experimental results are well in agreement with the theoretical model. Thus, the potential application of this method is to assess the performance of circuits or electronic systems.
Magnetization precession after non-collinear dual optical excitation
Authors: Parchenko Sergii , Pecchio Davide , Mondal Ritwik , Oppeneer Peter M. , Scherz Andreas
Published: May 2024

We investigate the impact of non-collinear dual optical excitation on magnetization precession in a permalloy thin film using two ultrashort laser pulses. By analyzing the magnetization dynamics using time-resolved magneto-optical methods, we find that excitation with two ultrashort optical pulses introduces a long-lasting modification of the electron system, as indicated by a sizable decrease in the precession frequency and a significant increase (approximately 25%) in the decay time. Our results reveal that the observed effect strongly depends on the respective polarizations of the two excitation pulses and the time delay between the two optical pulses. Our findings indicate the occurrence of a nonlinear opto-spin effect during photoexcitation with two interfering optical pulses, which can potentially be observed in various materials and at different photon wavelengths.
Improving the homogeneity of Halbach arrays by optimizing magnet combinations using a genetic algorithm
Authors: Bogaychuk A. , Ivshin E.
Published: May 2024

The purpose of this study was to test the effectiveness of using a genetic algorithm to find the optimal combination of permutations of permanent magnets in a Halbach magnet array in order to achieve the best magnetic field homogeneity in this work area. The test took place on a simple Halbach magnet array of 32 cubic permanent magnets. The magnetization of these magnets was preliminary assessed. Our calculations demonstrate that it is possible to achieve homogeneity of the magnetic field within the working area comparable to that of ideal identical magnetic blocks. Therefore, our study shows that combinatorics can be used to optimize homogeneity without selecting magnetic blocks, which can significantly reduce the cost of manufacturing the final structure.
Single-metalens-assisted polarization imaging and edge detection for target recognition
Authors: Fan Yandong , Jin Chunqi , Yang Jiayu , Zhu Fei , Li Wei
Published: May 2024

Simultaneous capture of various light information, including polarization and edge information of the objects, has consistently been a fundamental concern within the field of target recognition. However, these tasks are typically accompanied by bulky optical components and active illumination methods, which significantly restricts their use in compact and lightweight applications. Here, we demonstrate a metalens-assisted imaging system that can simultaneously achieve polarization imaging and optoelectronic edge detection in a single shot with low consumption. The dielectric metalens is designed to achieve polarization imaging by dispersing the input polarized light into two orthogonal components, resulting in optoelectronic isotropic edge detection of two-dimensional images after digital post-processing. Compared with the algorithmic methods using a convolution kernel, the proposed system has a much lower computational complexity. The work presented in this study demonstrates the potential applications in machine vision and paves the way for the development of compact target recognition and real-time image processing systems.
On the validity of the state space correspondence strategy based on k-nearest neighbor cross-predictability in assessing directionality in stochastic systems: Application to cardiorespiratory coupling estimation
Authors: Porta Alberto , de Abreu Raphael Martins , Bari Vlasta , Gelpi Francesca , De Maria Beatrice , Catai Aparecida Maria , Cairo Beatrice
Published: May 2024

We tested the validity of the state space correspondence (SSC) strategy based on k-nearest neighbor cross-predictability (KNNCP) to assess the directionality of coupling in stochastic nonlinear bivariate autoregressive (NBAR) processes. The approach was applied to assess closed-loop cardiorespiratory interactions between heart period (HP) variability and respiration (R) during a controlled respiration (CR) protocol in 19 healthy humans (aged from 27 to 35 yrs, 11 females) and during active standing (STAND) in 25 athletes (aged from 20 to 40 yrs, all men) and 25 non-athletes (aged from 20 to 40 yrs, all men). Over simulated NBAR processes, we found that (i) the SSC approach can detect the correct causal relationship as the direction leads to better KNNCP from the past of the driver to the future state of the target and (ii) simulations suggest that the ability of the method is preserved in any condition of complexity of the interacting series. Over CR and STAND protocols, we found that (a) slowing the breathing rate increases the strength of the causal relationship in both temporal directions in a balanced modality; (b) STAND is more powerful in modulating the coupling strength on the pathway from HP to R; (c) regardless of protocol and experimental condition, the strength of the link from HP to R is stronger than that from R to HP; (d) significant causal relationships in both temporal directions are found regardless of the level of complexity of HP variability and R. The SSC strategy is useful to disentangle closed-loop cardiorespiratory interactions.
Effects of drive pulse shape on graded metal pushered single shell capsule implosions on the National Ignition Facility
Authors: Dewald E. L. , MacLaren S. A. , Ho D. D.-M. , Martinez D. A. , Pino J. E. , Tipton R. E. , Young C. V. , Horwood C. , Divol L. , Rubery M. S. , Moore A. , Vazsonyi A. R. , Mellos G. , Montgomery W. , Smalyuk V. A. , Graziani F. , Monzon E. , Prisbrey S. T. , Whitley H. D. , Xu H. , Huang H. , Kong C. , Ratledge M. , Volegov P. , Freeman M. S. , Wilde C. , Meaney K.
Published: May 2024

Graded metal pushered single shells (PSS) are a viable alternative to low-Z capsules (Z is the atomic number) for indirect drive inertial confinement fusion implosions due to enhanced core tamping and radiation trapping, but they can be compromised by the pusher mixing with the fuel. We compare 2-shock and 3-shock laser pulses for Be/Cr PSS capsules filled with deuterium–tritium gas fuel at 6 mg/cc density. 1D radiation-hydrodynamic simulations predict higher core compression and, hence, ∼2× higher fusion yield for the 3-shock drive than for 2-shock. Nevertheless, we observe similar core ion temperatures and fusion yields for both drives. The implosion burn duration is 25% shorter and the core volume is ∼2.5× smaller for the 3-shock drive than for 2-shock, consistent with a higher compression. 1D LASNEX mix simulations using a buoyancy-drag model matching the measured yields also agree with the observed core sizes and burn durations and suggest ∼40% and ∼70% yield degradations for 2-shock and 3-shock drives due to hydrodynamic instabilities and atomic mix at the pusher–fuel interface. At the same time, 2D HYDRA simulations show that mid-mode (2–250) instability degradations are negligible for the 2-shock implosion (9%) and significant (45%) for 3-shock. Subtracting these from the 1D mix simulations, we infer similar degradations from high-mode instabilities and atomic mix for both drives. Due to its robustness to mid-mode instabilities, future pusher–gas mix studies will use the 2-shock drive.
Non-amphoteric N-type doping with Sn of GaAs(631) layers grown by molecular beam epitaxy
Authors: Mora Herrera M. F. , Espinosa-Vega L. I. , Cortes-Mestizo I. E. , Olvera-Enriquez J. P. , Belio-Manzano A. , Cuellar-Camacho J. L. , Gorbatchev A. Yu. , Del Rio-De Santiago A. , Yee-Rendón C. M. , Méndez-García V. H.
Published: May 2024

The Sn-doping effects on the electrical conduction and optical properties of GaAs(631)A epilayers grown by molecular beam epitaxy were investigated. We found that the conduction type conversion, frequently observed in the doping of layers grown on high-index substrates, is avoided when tin-doping is implemented. The maximum free-carrier concentration (n) obtained in GaAs(631):Sn was 2 × 1019 cm−3, an order of magnitude higher than previously reported for GaAs(631):Si, and within the same order of magnitude for the growth of GaAs(100):Si. The electron mobility was suitable for many optoelectronic applications. Raman spectroscopy showed low lattice disorder in (631) oriented samples, compared with singular (100) samples. The photoluminescence characterization of the samples revealed the blueshift of the optical transitions close to E0 associated with the Moss–Burstein effect for Sn doping. Photoreflectance spectroscopy was used to study the doping properties at the critical points E1 and E1 + Δ1, where the major affectation with n was perceived in the broadening parameter Γ.
Collective dynamics and shot-noise-induced switching in a two-population neural network
Authors: Kirillov S. Yu. , Smelov P. S. , Klinshov V. V.
Published: May 2024

Neural mass models are a powerful tool for modeling of neural populations. Such models are often used as building blocks for the simulation of large-scale neural networks and the whole brain. Here, we carry out systematic bifurcation analysis of a neural mass model for the basic motif of various neural circuits, a system of two populations, an excitatory, and an inhibitory ones. We describe the scenarios for the emergence of complex collective behavior, including chaotic oscillations and multistability. We also compare the dynamics of the neural mass model and the exact microscopic system and show that their agreement may be far from perfect. The discrepancy can be interpreted as the action of the so-called shot noise originating from finite-size effects. This shot noise can lead to the blurring of the neural mass dynamics or even turn its attractors into metastable states between which the system switches recurrently.
Dynamic exploration of laser linewidth compression in resonant feedback external-cavity laser
Authors: Zhang Chaoze , Huang Ligang , Guan Tianyu , Mao Yuqin , Li Jiali , Gao Lei , Huang Wei , Shi Leilei , Yin Guolu , Zhu Tao
Published: May 2024

An external-cavity laser with resonant optical feedback is a common and mature method to achieve narrow linewidth lasers. Since the proposal of optical feedback in 1964, a series of studies on resonant optical feedback have been reported. Although longer feedback length leads to narrower linewidth, it also introduces coupling of environmental noise and causes instability in the laser cavity, which is detrimental to high-speed tuning of the laser wavelength. With such a challenge, current research on resonant optical feedback primarily focuses on the static results of laser linewidth compression. In order to obtain narrow linewidth high-speed tuned external-cavity lasers, further research on the laser dynamics is required to obtain dynamic tuning of narrow linewidth external-cavity lasers. In this work, we construct an external-cavity laser based on resonant optical feedback, and utilize a coherent detection method to measure the dynamic process of laser linewidth compression and wavelength tuning. Based on resonant optical feedback from the external cavity, the linewidth of the main-cavity laser can be compressed from near 100 kHz to the 100 Hz level, with the frequency noise compressed from the order of 104 to the 102 Hz2/Hz level. Since the wavelength switching process includes frequency shift process, linewidth compression process, and frequency stabilization process, etc., we first conduct a research on laser linewidth compression dynamics. In the results of linewidth compression dynamics, we discover that using a shorter fiber ring results in shorter linewidth compression time, which is advantageous for laser dynamic tuning. We subsequently carry out the laser wavelength switching process with a main-cavity switching time in milliseconds. In the wavelength switching process, while undergoing the frequency shift process of fast tuning transient laser frequency, the laser first undergoes the linewidth broadening process, then enters the main-cavity laser frequency stabilization process and undergoes the linewidth compression process at the same time. The experimental results show that the 100 m feedback fiber ring will not significantly increase the external-cavity laser wavelength switching time under the condition that linewidth compression is faster than main-cavity laser switching, while a longer fiber ring will introduce a strong noise. Our work experimentally demonstrates that shorter feedback ring lengths lead to faster compression, which provides valuable insights for the development of high-speed and high-precision tunable narrow linewidth external-cavity lasers.