bluuebunny/crossref_metadata_2025 huggingface dataset:
Ground Interaction Models for Increased Autonomy of Planetary Exploration Systems
Authors: Dettmann Alexander , Langosz Malte , Eisenmenger Jonas , Otto Marc , Kasperski Sebastian , Wirkus Malte , Lessa Nayari Marie
Published: March 2024

Future planetary exploration robots need to improve their autonomy to increase mission safety and efficiency. The presented concept achieves this by introducing the learning and usage of ground interaction models, which allow a more precise modelling of the robot’s mobility on different terrains. The idea is that a precise prediction of the expected performance will, on the one hand, allow an early detection of changed conditions and, on the other hand, enable a system to appropriately react on it. By classifying the traversed terrain, a robot gains the possibility to replan its path or to change its locomotion behavior to eventually optimize mission success. The paper provides details, on how the ground interaction models are trained, how the required data is collected, and how they are embedded into a physical simulator to use them online on the system.
Design and testing of mechanical gripping tools for On Orbit assembling
Authors: Mulsow Niklas Alexander , Dabrowski Adam , Mallwitz Martin , Maisch Leonard
Published: March 2024

On-orbit servicing, assembly and manufacturing (OSAM) opens a new frontier for robotic systems. A gripping tool for such applications must meet several requirements of space mechanics, such as safety, precision and reliability, while functioning in space conditions. This paper presents a development cycle of such tools designed for the assembly of a small satellite antenna on the International Space Station. Two different grippers, driven by a common drive unit, are presented, conforming to a Multi-Purpose-Tool (MPT) for orbital robotic systems and meeting the requirements of a defined OSAM mission. Both design drivers and concepts and specific component selection are described. Proposed mechanical solutions for safe gripping of objects including space tribology aspects are covered. To adapted to operations not foreseen, the grippers and the drive unit can be reconfigured. The tool architecture presented promotes modularity, scalability, reusability and convertibility of designs, thus facilitating rapid integration in similar missions. A test campaign for critical requirements will be in place to ensure reliable performance of the tools for use in the space environment.
Use of thermal data to estimate satellite rotation rate in the UPMSat-2
Authors: Porras-Hermoso A. , Piqueras J. , Cubas J. , Roibás-Millán E. , Alonso A. , Valante H.
Published: March 2024

Attitude determination is a fundamental task of the Attitude Determination and Control Subsystem (ADCS). It involves determining the spacecraft’s orientation with respect to a reference system and calculating its angular velocity, which is essential for understanding where the payload is pointing and the spacecraft’s stability. The determination of the attitude is obtained using sensors such as Sun sensors, Nadir sensors, or Star trackers. Regarding the spacecraft angular velocity, gyroscopes or MEMs can be used to measure the angular velocity of the satellite, but in their absence the velocity can be derived from the attitude data of the other sensors. However, this method requires a sampling rate to be twice the frequency of the movement, otherwise the angular velocity cannot be calculated with traditional methods. To address this issue, this study proposes a thermal analysis of the external temperatures of a rotating satellite to obtain its rotation rate. This method is especially useful for satellites with low or limited data sample rates. The proposed methodology is used in the UPMSat-2 case to demonstrate the functionality of its experimental ADCS.
Assessing the Risk of Uncontrolled Space Debris Re-entry: A Case for Airspace Management and Flight Safety
Authors: Stefanescu I B , Constantinescu C E , Pleter O T
Published: March 2024

We explore the risks associated with uncontrolled space debris re-entry and the implications for airspace management and flight safety. With the increasing number of satellites and other objects being launched into space the potential for uncontrolled re-entry events poses a unique challenge for airspace management and public safety. While there have been no recorded instances of aircraft damage or human injury due to re-entering space debris, the increasing frequency of such events necessitates a comprehensive understanding of the associated risks and appropriate mitigation strategies. We briefly examine the current methods for tracking and predicting space debris re-entry, concentrating on the decision-making process for airspace closures, and the risk assessment for ground airborne safety. Our analysis aims to contribute to the ongoing dialogue on space debris management and to inform future policy and operational decisions in the context of civil aviation and public safety.
Study on schottky barrier of Cu/Graphene/4H-SiC interface based on first principles
Authors: Wang Congcong , Wu Siyu , Jiang Zhenyu , Huang Yingjie
Published: March 2024

High stability 4H-SiC ohmic contact is currently a key technical challenge that silicon carbide devices urgently need to overcome. In the paper, the interfacial structures, atomic interactions and Schottky barrier height (SBH) of Cu/Graphene/4H-SiC were studied using the first-principles method. According to research, the SBH for Cu/G/4H-SiC is lower than the SBH for Cu/4H-SiC. The reasons for this phenomenon mainly include the following: 1. The graphene C atoms saturate the dangling bonds on the 4H-SiC surface and the influence of the metal-induced-gap-states (MIGS) at the interface is decreased. 2. A new phase is formed by inserting graphene between the Cu and 4H-SiC have low work functions. 3. An interfacial-electric-dipole layer (IEDL) formed at the interface of 4H-SiC and graphene may also reduce the SBH. These results make them to be promising candidates for future radiation resistant electronics.
Synthesis of g-C3N4/HC composite and its visible light catalytic performance
Authors: Liu Jinshan , Zhu Yuwei , Ren Yulan , Li Heruo , Gao Shuang , Wu Jianfei
Published: March 2024

Thermal polymerization prepared g-C3N4/HC composite with good visible light catalytic ability using corn stover and urea as raw materials. The structure of the g-C3N4/HC composite was characterized by XRD, and it was determined that the composite was composed of g-C3N4 and HC. The morphology of the g-C3N4/HC composite was characterized by SEM. g-C3N4 is dispersed in sheet form on HC tubes with a regular porous structure. The degradation efficiency of RhB by g-C3N4/HC reached 99.14% after 70 min irradiation by a 70 W metal halide lamp. The cyclic degradation experiments proved that g-C3N4/HC has good reusability. Compared with g-C3N4, the visible light absorption capacity of g-C3N4/HC is enhanced, and the electron-hole recombination rate is also reduced, which results in the higher photocatalytic capacity of g-C3N4/HC. The free radical trapping experiments confirmed that the hole free radical and the hydroxyl free radical are the primary active substances in the photodegradation reaction.
Anti-icing application of superhydrophobic coating on glass insulator
Authors: Fan Lei , He Jinhang , Li Bo , Xia Mingyong , Liu Jian , Zhu Tao , Zhao Yingying , Hua Xujiang , Yuan Yuan
Published: March 2024

Insulators, as important components in transmission lines, are prone to disturb the safe running of the power system by the ice accumulation on surfaces. Traditional anti-icing coatings are difficult to practically apply to insulators. Here, superhydrophobic (SHP) coatings were fabricated on the glass insulator surface by spraying. We studied microstructure, wettability, water droplet bouncing behavior, and anti-glaze icing properties of SHP coating. The results demonstrated that SHP coatings had micro-nano rough structures. The excellent superhydrophobicity (contact angle of 165.2° and sliding angle of 3.7°) was achieved. The water droplet was easily adhered to the surface of the glass insulators. At the same time, individual water droplets could bounce away from the surface after impacting the SHP coating. In the glaze environment, water droplets sprayed onto the SHP coating merged with each other and slid off the surface. These significantly reduce the likelihood of freezing. Furthermore, the SHP coating could dramatically delay the glaze icing and decrease the icing area. The icing weight and icicle length were smaller than glass insulators. The SHP coatings prepared in this work display great potential for the anti-icing of glass insulators.
The effect of dispersion degree of calcium carbonate particles in polyvinyl chloride matrix on the mechanical properties of composites
Authors: Luo Shijun , Pan Sining , Chang Hongbin , Zhou Xiaolin
Published: March 2024

By establishing representative volume units of polyvinyl chloride (PVC) matrix composites filled with calcium carbonate (CaCO3) particles with different agglomeration degrees, finite element simulation analysis is conducted to predict the degree of improvement of the mechanical properties of the CaCO3/PVC composites by the dispersion degree of calcium carbonate particles. When the agglomeration coefficient is 0.4, the stress concentration phenomenon of the CaCO3/PVC composites is the weakest, and the stress distribution of the entire CaCO3/PVC composites is relatively uniform. At the same time, the reinforcement effect of the CaCO3/PVC composites’s stiffness is also the best, increasing by 13.8%.
Effect of crosslinking agent types on the tensile properties of polyisoprene rubber
Authors: Zuo Junjie , Wei Zhigang , Zhang Zelin
Published: March 2024

The impacts of crosslinking bond types on the equilibrium kinetics and uniaxial tensile properties of polyisoprene rubber were investigated by using molecular dynamics (MD) simulations. We analyze the changes in mean square displacement, glass transition temperature, and end-to-end vector autocorrelation function of different crosslinked systems during the equilibrium process. It was found that the mobility of polysulfide crosslinked systems was more limited compared with that of monosulfide and disulfide bonds. In addition, during uniaxial stretching, the polysulfide-bonded crosslinked system could exhibit better tensile strength, and the stress response was significantly improved. The above research results help to understand the mechanical properties and deformation mechanism of crosslinked polyisoprene rubber and provide certain reference values for improving the performance of related materials.
Preparation and application research of transition metal phosphides
Authors: Li Deming , Fang Xing , Zhang Bo , Chen Songlin , Yuan Guojun
Published: March 2024

Due to the serious environmental pollution in the world, the shortcut to harmonious development is to improve traditional disposable energy and identify new energy sources that can be utilized. The current problem that human society must solve is to discover and use efficient and inexhaustible new energy sources, among which electrolytic water technology is an effective way to develop clean energy. In recent years, researchers have focused on producing hydrogen by electrolyzed water, but the intermediate hydrogen evolution reaction and the oxygen evolution reaction are relatively slow kinetic processes, and they cannot give the factory a large range of electrolytic water hydrogen production work and push down the commercialization process, so improving the rate of electrolytic water process must be an efficient catalyst. Transition metal phosphide is one of the non-precious metal catalysts in the electrochemical hydrogen evolution reaction and oxygen evolution reaction. Transition metal phosphide can promote rapid change of chemical reaction rate, and it has the characteristics of being cheap and easy to operate so it has a great prospect in the electrolysis of water. In this experiment, the oxygen evolution performance was optimized based on the crystal surface regulation of cobalt-doped transition metal nickel phosphide. The optimal reduction time and a small overpotential (60 mV) were obtained by using sodium borohydride to reduce the sample.
Structural safety of compressed air energy storage sealing materials
Authors: Liu Jing , Di Shengjie , Lu Xi , Ji Yang
Published: March 2024

The structural safety of sealing materials is one of the important technical problems of compressed air energy storage. FLAC3D is used to analyze and compare various combination schemes using steel lining and flexible material as sealing materials and evaluate the safety of each scheme, which provides a reference for the design of high-pressure gas storage. The contact surface between the concrete and the steel lining is set up to enhance the relative sliding between them, which is conducive to the coordination of steel plate deformation and the reduction of steel plate stress. The stress of steel plate can be significantly reduced by placing some flexible materials in steel plate and lining concrete, and the lower the modulus of flexible materials is, the better the stress of steel plate structure is.
Effect of ultrasonic surface rolling on the friction and wear properties of 8620H carburized steel at elevated temperatures
Authors: Zhong Hao , Qu Shengguan , Long Wang , Deng Rixin , Zhou Wenxue
Published: March 2024

The surface strengthening treatment of 8620H carburized steel was carried out by ultrasonic surface rolling (USR) process, and the samples with and without the treatment were subjected to friction and wear experiments at 25°C, 100°C, and 150°C. The experimental results showed that the samples with USR treatment had higher surface hardness, lower surface roughness, deeper hardened layer depth, and higher surface residual compressive stress than the samples without USR treatment. Meanwhile, the wear degree of the samples deteriorated as the temperature increased, but the anti-wear performance of the samples with USR treatment increased by 52.9%, 29.8%, and 14.9% compared with the samples without USR treatment at 25°C, 100°C, and 150°C, respectively, indicating that the USR treatment still had a better strengthening effect at high temperatures.
Vector ducted propeller aerodynamic modeling and verification testing
Authors: Tang Peng , Zhao Chuangxin , Mao Sen , Tian Jiajie , Liang Shizhe
Published: March 2024

The tail-sitter aircraft has the advantages of both high-speed cruise and capability of the take-off and land vertically, high-performance control laws usually rely on the accurate flight mechanics model, while its flight aerodynamic modeling is a complex problem. This paper analytically develops an aerodynamic model of its propelling system based on first principles, including three components of a propeller, a vector duct, and eight slipstream vanes. This model can give the propeller’s induced velocity, power, thrust, and moment, also considers the augmented effect of ducted, and the lift and drag forces of vanes. Moreover, a propelling system test bed is built to measure the forces and moments along the body frame, which is composed of the tail-sitter prototype, power, communication link, upper system, and servo drive device. In addition, experimental results show the effectiveness of the model in estimating the thrust and torque with different angles of control vanes, the measured thrust is consistent with the calculated values, and the steering performance of each vane is further examined. The moments exerted on the two axes are linear with the vanes angles, and the symmetry is also well, which is convenient for flight controller design for this type of tail-sitter aircraft.
Research on hydrogen induced cracking (HIC) performance of vessel steels
Authors: Fan Yanqiu , Ma Changwen , Li Shaopo , Ding Wenhua , Liu Yang , Li Zhanjun , Chu Rensheng
Published: March 2024

Hydrogen-induced cracking performance is quite important for vessel steels. But for this type of medium carbon steel, studies on the effect of the dislocation density and distribution condition of carbides on hydrogen-induced cracking performance were insufficient. In this study, the tested steel was treated with three different heat-treatment processes: scanning electron microscopy (SEM), hydrogen-induced cracking tests (HIC), and transmission electron microscope (TEM), which were used to reveal the mechanism of affecting hydrogen-induced cracking performance. The results showed that microstructure, dislocation density, and distribution condition of carbides were the significant key to the hydrogen-induced cracking performance of tested steels. As the tempering temperature grew from 450°C to 650°C, the density of dislocation gradually went down from 9.71/1010 cm-1 to 2.97/1010 cm-1. And the shape of carbides transformed from bar into fine particles, and the area fraction increased from 37% to 44%. More uniformly distributed carbides can enhance hydrogen-induced cracking resistance because it can promote trapped hydrogen atoms uniformly distribute, reduce the local hydrogen pressure and prohibit crack initiation and propagation. In other words, a tempering temperature above 550°C would be beneficial for the hydrogen-induced cracking performance of vessel steels.
Research on the high-speed impact of projectiles on reinforced concrete equivalent targets
Authors: Qi Hongli , Wang Xinying , Qin Yi , Wen Qiye
Published: March 2024

Due to the prolonged production cycle of reinforced concrete target plates and the need for a series of preparations and tests before use, it is essential to study the equivalent relationship between reinforced concrete target plates and steel target plates. Numerical simulations of the process of projectiles vertically penetrating reinforced concrete target plates were conducted using LS-DYNA software. Models for both reinforced concrete and steel targets were established, and the equivalent thickness conversion relationship between the two was obtained. Simulation results indicated an inverse proportional relationship between projectile residual kinetic energy and target thickness. Curve fitting using Origin software was performed to obtain the conversion relationship between the thicknesses of reinforced concrete target plates and steel targets. The simulation results were validated, showing an error in concrete target plate thickness conversion of less than 10%. The research results provide theoretical support and data references for the equivalent study of reinforced concrete target plates and steel target plates.
First-principles study on interfacial reaction of SiCO/LTaO for all-solid-state lithium-ion batteries
Authors: Xu Changgui , Chen Zhirong , Liao Ningbo
Published: March 2024

Silicon oxycarbide is an excellent anode material for all solid batteries, characterized by excellent stability and some oxidation resistance. The structure of the SiCO/LTaO system has been investigated using first principles. We have investigated the electron density, DOS, and energy band structure at the SiCO/LiTaO interface. The calculations note that this particular configuration is expected to be applied to such as lithium-ion batteries and supercapacitors. This work will provide some theoretical support for the difficult problem of lowering impedance in the preparation of all-solid-state lithium-ion batteries.
Photoluminescence properties of Sr3Y2(BO3)4: Eu3+ phosphor codoped with Gd3+ and La3+ under ultraviolet excitation
Authors: Jia Linyan , Cong Zichun , Zhang Liping
Published: March 2024

Sr3Y2 (BO3)4: Eu3+ phosphor codoped with Gd3+ and La3+ was generated using the solid state method, and XRD and fluorescence spectrum researched the structure and luminescence properties. The strongest excitation peak of Sr3Y2 (BO3)4:Eu3+ is in the near ultraviolet region of 394 nm, which comes from the 7F0 → 5L6 transition of Eu3+. With the stimulation of 394 nm ultraviolet-light, the strongest emission of Sr3Y2 (BO3)4:Eu3+ phosphor is a red light with a wavelength of 618 nm. It is produced by the transition of 5D0 → 7F2 of Eu3+. The optimum preparation temperature is 1000°C, and the doping amount of Eu3+ is 5% (mol). The doping of Gd3+ and La3+ greatly enhanced the luminescent intensity of Sr3Y2 (BO3)4:Eu3+ phosphor, and the doping of 20% (mol) was suitable.
Medium-range order structure analysis of metallic glasses based on reverse Monte Carlo modeling
Authors: Liu Yuan , Luo Jingrun , Huang Xin , Li Jiaxing
Published: March 2024

The elucidation of amorphous alloy characteristics presents a formidable challenge due to the absence of crystalline arrangements and enigmatic imperfections. This study aimed to tackle this challenge through a comprehensive investigation utilizing synchrotron X-ray diffraction (XRD), extended X-ray absorption fine structure spectroscopy (EXAFS), ab initio molecular dynamics (AIMD) simulations, and reverse Monte Carlo (RMC) modeling. The primary objective was to delve into the medium range order (MRO) structure of metallic glasses (MGs) containing CuXZr100-X, wherein X represents values of 50, 56, 60, and 64. The results obtained from this research demonstrate that an increase in the Cu atom concentration within Cu-Zr MGs leads to the formation of complete icosahedral clusters and high-coordination polyhedral connections, thereby bolstering the stability and heterogeneity of local structures. Examination of the stiff full icosahedral bones shows that defects exist in the network connections on the MRO, resulting in a lack of connectivity in the positive icosahedron. Conversely, the density of defects decreases with an increase in Cu content. The observation suggests that the observed low MRO defects in Cu64Zr36 MGs may be accountable for their excellent glass-forming ability and kinetic stability.
Continuous carbon fiber 3D printing partitioning method based on stress distribution
Authors: Qiu Wen , Zhang Fan , Tan Yuegang , Zhang Jun , Tu Yiwen
Published: March 2024

3D printing of continuous carbon fiber composites presents a need for the directivity of fiber distribution. For parts with actual working conditions, the stress distribution of the same part under the same stress condition is different, but the existing partitioning algorithm mainly fills the path of the subregion according to the shape of the part, and does not combine the working condition of the part. To solve this problem, a partitioning algorithm based on stress contour density is proposed. Based on the results of finite element analysis, the stress contour of the parts is obtained, and the stress concentration area is partitioned by calculating the stress contour density. The stress concentration area is filled with a more suitable path to improve the performance of the parts.
Estimation of the residue capacity of lithium iron phosphate battery based on the internal resistance obtained from charging voltage drop
Authors: Yin Jingyun , Yu Jingmei , Zhang Wenfeng , Zhou Qinhe , Huang Canjun
Published: March 2024

This study takes the 80 Ah lithium iron phosphate (LFP) prismatic battery that is from the vehicle and is in the middle or end of life as the research target, and the voltage-drop resistance (VDR), which is calculated through the voltage drop at the charging end, is used to for residue capacity estimation. The relationship between the VDR and the residue capacity of the battery is systematically studied, including factors such as charging cut-off voltage, charging current, charging end time, and charging current change mechanism. The results show that the residue capacity is a quadratic function relationship with the charging cut-off voltage and VDR. The VDR is affected by the charging cut-off voltage, charging cut-off current, and charging end time. There is no significant difference in the influence of VDR obtained by the charging modes of step charging and constant current charging. By testing the VDR under different charging conditions and different resting times, and standardizing the VDR, the residue capacity estimation error of 97% of the vehicle’s batteries is within ±5%, which meets the application requirements for residue capacity estimation.
Study on the Influence of Hydrogen Blended Transportation on the Safety of Existing X70 Steel in Gas Distribution Pipeline Network
Authors: Guo Baoling , Zhang Yanqi
Published: March 2024

Coal to gas is one of the natural gas sources utilized in Beijing, with a hydrogen blend concentration range from 1% to 3% and reaching up to 5% in specific cases. In order to evaluate the safety of transporting hydrogen blended natural gas with X70 pipeline steel in distribution pipelines, this study first conducted the slow strain rate tensile tests under a total pressure of 4 MPa in hydrogen environment. The results show that X70 steel exhibits highly sensitive to a hydrogen blending ratio of 5%. Subsequently, four types of hydrogen compatibility tests were conducted in the above sensitive hydrogen partial pressure include the impact toughness test, fracture toughness test, fatigue crack growth test, and fastening disk pressure test. The findings demonstrated that hydrogen blended natural gas has virtual no effect on the impact and fracture toughness, with only 10% reduction in fatigue crack growth threshold. Finally, based on fatigue life analysis by fracture mechanics evaluation, it can be concluded that the existing natural gas pipe of X70 steel is capable to operate safely over 40 years under a total pressure of 4 MPa with a hydrogen blend concentration of 5%.
Study on the thermodynamic and economic performance of power generation cycle with small temperature difference
Authors: Hao Ning , Liu Chuanliang , Wang Dexuan , Li Zhenya , Bian Wenjie
Published: March 2024

The low thermal efficiency and low economic benefits of power generation systems under small temperature difference conditions have always hindered their practical operation. In order to explore effective ways to achieve performance optimization of thermodynamic cycle electrical power generating systems under small temperature difference conditions, this study constructs a static analysis model of an organic Rankine cycle with small temperature difference, selects six different commonly used refrigerants, and investigates the influence of key parameters on the thermodynamic and economic performance of the system using difference working fluids. The outcomes indicate that key parameters such as evaporation temperature and condensation temperature play a critical role in the thermodynamic and economic performance of the power generation system. For the working fluids, R227ea provides the highest net power output, while ammonia (R717) is the best performer in regard to system thermal efficiency and economic performance.
Study on synthesis and properties of polyacrylate wax inhibitor
Authors: Gao Xiang , Zhang Yuandan , Li Zhe , Wang Xinmin , Du Yingna
Published: March 2024

Synthesis and properties of polyacrylate ester paraffin inhibitior based on polyacrylate ester start from dodecanol, tetradecanol, hexadecanol, octadecanol respectively were introduced in this paper. Hexadecyl polyacrylic showed the most potent paraffin inhibition, and then the optimum reaction condition of it was ascertained. The percentage inhibition of hexadecyl polyacrylic, synthesized under the optimized conditions, reached to 79.3%. Then crosslinked polyacrylate ester paraffin inhibitiors were synthesized and screened by static wax precipitation experiment, and find the percentage inhibition of crosslinked hexadecyl polyacrylic reached to 88.4%.
Performance profiling and design choices of an RDMA implementation using FPGA devices
Authors: Vasile M. , Iancu V. , Martoiu S. , Stoicea G. , Boukadida N. , Hobincu R.
Published: March 2024

RDMA communication is an efficient choice for many applications, such as data acquisition systems, data center networking and any other networking application, where high bandwidth and low latency are necessary. RDMA can be implemented using a large array of options, which need to be tailored to the needed use case, in order to get optimal results. Aspects such as the effects of using multiple simultaneous connections, using various transport functions such as RDMA Write and RDMA Send and communication models such as sending individual bursts or continuous streams of data will be investigated for implementing RDMA on FPGA devices.
Uniform accuracy of implicit-explicit Runge-Kutta (IMEX-RK) schemes for hyperbolic systems with relaxation
Authors: Hu Jingwei , Shu Ruiwen
Published: March 2024

Implicit-explicit Runge-Kutta (IMEX-RK) schemes are popular methods to treat multiscale equations that contain a stiff part and a non-stiff part, where the stiff part is characterized by a small parameter

ε
\varepsilon

. In this work, we prove rigorously the uniform stability and uniform accuracy of a class of IMEX-RK schemes for a linear hyperbolic system with stiff relaxation. The result we obtain is optimal in the sense that it holds regardless of the value of

ε
\varepsilon

and the order of accuracy is the same as the design order of the original scheme, i.e., there is no order reduction.
Changing interim monitoring in response to internal clinical trial data
Authors: Proschan Michael A , Nason Martha , Ortega-Villa Ana M , Wang Jing
Published: March 2024

Designing clinical trials for emerging infectious diseases such as COVID-19 is challenging because information needed for proper planning may be lacking. Pre-specified adaptive designs can be attractive options, but what happens if a trial with no such design needs to be modified? For example, unexpectedly high efficacy (approximately 95%) in two COVID-19 vaccine trials might cause investigators in other COVID-19 vaccine trials to increase the number of interim analyses to allow earlier stopping for efficacy. If such a decision is based solely on external data, there are no issues, but what if internal trial data by arm are also examined? Fortunately, the conditional error principle of Müller and Schäfer (2004) can be used to ensure no inflation of the type 1 error rate, even if no interim analyses were planned. We study the properties, including limitations, of this method. We provide a shiny app to evaluate changes in timing of interim analyses in response to outcome data by arm in clinical trials.
Use of proton pump inhibitors is associated with increased risk of out-of-hospital cardiac arrest in the general population: a nested case-control study
Authors: Eroglu Talip E , Coronel Ruben , Gislason Gunnar H
Published: March 2024

Aims

Proton pump inhibitors (PPIs) impair cardiac repolarization, prolong the QT interval, and may potentially be pro-arrhythmic. However, the risk of out-of-hospital cardiac arrest (OHCA) is scarcely investigated. We studied whether past or current PPI use is associated with OHCA in the general population.

Methods and results

We conducted a nationwide nested case-control study with OHCA-cases of presumed cardiac causes and age/sex/OHCA-date-matched non-OHCA-controls from the general population. Exposure to PPI was categorized into three mutually exclusive groups of current-, past-, and non-use. Conditional logistic regression analyses with adjustments for risk factors of OHCA were used to calculate the odds ratio (OR) of OHCA comparing PPI use with non-users. We identified 46 578 OHCA cases and 232 890 matched non-OHCA controls (mean: 71 years, 68.8% men). PPI was used by 8769 OHCA-cases and 21 898 non-OHCA controls, and current use of PPI was associated with increased odds of OHCA compared with non-users [OR: 1.32 (95% CI: 1.28–1.37)], while past use conferred no increase in the odds of OHCA [OR: 1.01 (95% CI: 0.98–1.04)]. This increased odds of OHCA occurred in both sexes. Finally, the ORs remained elevated when we repeated the analyses in individuals without registered ischaemic heart disease [OR: 1.36 (95% CI: 1.31–1.41)], without heart failure [OR: 1.33 (95% CI: 1.29–1.38)], or without any cardiovascular comorbidities [OR: 1.84 (95% CI: 1.70–2.00)]. Also, the OR remained elevated when H2-antagonists served as the reference group [OR: 1.28 (95% CI: 1.11–1.47)].

Conclusion

PPI use is associated with an increased risk of OHCA in the general population. Considering the widespread use of PPIs, this study raises concerns and the need for awareness to balance the benefit and risk of treatment.
The Discourse of ‘The People’s War’ in Britain and the USA during World War II
Authors: Dettman Sean , Toye Richard
Published: March 2024

David Edgerton has argued that the term ‘people’s war’ was not much in use during World War II and that where it did occur it was used in ‘a critical and oppositional, rather than an official-celebratory’ sense. We show that Edgerton’s conclusions are an artefact of his limited source-base and narrow reading of the evidence. The phrase ‘people’s war’ was in fact used in Ministry of Information propaganda and cropped up widely in the press, leading contemporaries to comment on its overfamiliarity. But we do not merely seek to restore previous interpretations. We show the longer history of ‘people’s war’ terminology in both Britain and America. We further demonstrate how Britain’s US sympathisers, such as the CBS journalist Edward R. Murrow, used this language to argue that British class barriers were breaking down, thus making the country worthy of American support. British policymakers consciously encouraged this, and there were consequences for US domestic politics too. The concept of the ‘people’s war’, then, was a contemporary Anglo-American co-production. It was not, as Edgerton wrongly suggests, an invention of the historians of the 1960s and after.
Clinician perspectives on integrating neuro-oncology and palliative care for patients with high-grade glioma
Authors: Crooms Rita C , Nnemnbeng Jeannys F , Taylor Jennie W , Goldstein Nathan E , Gorbenko Ksenia , Vickrey Barbara G
Published: March 2024

Background

Patients with high-grade glioma have high palliative care needs, yet few receive palliative care consultation. This study aims to explore themes on (1) benefits of primary (delivered by neuro-oncologists) and specialty palliative care (SPC) and (2) barriers to SPC referral, according to a diverse sample of clinicians.

Methods

From September 2021 to May 2023, 10 palliative physicians and 10 neuro-oncologists were recruited via purposive sampling for diversity in geographic setting, seniority, and practice structure. Semistructured, 45-minute interviews were audio-recorded, professionally transcribed, and coded by 2 investigators. A qualitative, phenomenological approach to thematic analysis was used.

Results

Regarding primary palliative care, (1) neuro-oncologists have primary ownership of cancer-directed treatment and palliative management and (2) the neuro-oncology clinic is glioma patients’ medical home. Regarding SPC, (1) palliative specialists’ approach is beneficial even without disease-specific expertise; (2) palliative specialists have time to comprehensively address palliative needs; and (3) earlier SPC enhances its benefits. For referral barriers, (1) appointment burden can be mitigated with telehealth, home-based, and embedded palliative care; (2) heightened stigma associating SPC with hospice in a population with high death anxiety can be mitigated with earlier referral to promote rapport-building; and (3) lack of neuro-oncologic expertise among palliative specialists can be mitigated by emphasizing their role in managing nonneurologic symptoms, coping support, and anticipatory guidance.

Conclusions

These themes emphasize the central role of neuro-oncologists in addressing palliative care needs in glioma, without obviating the need for or benefits of SPC. Tailored models may be needed to optimize the balance of primary and specialty palliative care in glioma.
The relationship between aggregate uncertainty and firm-level uncertainty
Authors: Easaw Joshy , Grimme Christian
Published: March 2024

Many firm-level studies use aggregate uncertainty to proxy for firm-level uncertainty. Providing support for this strategy, we analyse the extent to which firm-level uncertainty is affected by aggregate uncertainty. Firm-level uncertainty is constructed from a large and monthly panel dataset of manufacturing firms. We find that aggregate uncertainty is associated positively and robustly with firm-level uncertainty. This correlation holds across different types of domestic and international measures of aggregate uncertainty. However, the extent of the correlations is heterogeneous and depends on certain firm characteristics and the state of the business cycle. For example, the widely used economic policy uncertainty index matters to all firms’ uncertainty only in recessionary periods, while it is relevant over the entire business cycle only to large firms’ uncertainty.
Pharmacotherapeutic Considerations in the Treatment of Nontuberculous Mycobacterial Infections: A Primer for Clinicians
Authors: Cimino Christo , Rivera Christina G , Pearson Jeffrey C , Colton Benjamin , Slain Douglas , Mahoney Monica V
Published: March 2024

Nontuberculous mycobacteria (NTM) can cause a variety of infections, including serious pulmonary disease. Treatment encompasses polypharmacy, with a targeted regimen of 2–5 active medications, depending on site of infection, species, and clinical characteristics. Medications may include oral, intravenous, and inhalational routes. Medication acquisition can be challenging for numerous reasons, including investigational status, limited distribution models, and insurance prior authorization. Additionally, monitoring and managing adverse reactions and drug interactions is a unique skill set. While NTM is primarily medically managed, clinicians may not be familiar with the intricacies of medication selection, procurement, and monitoring. This review offers insights into the pharmacotherapeutic considerations of this highly complex disease state, including regimen design, medication acquisition, safety monitoring, relevant drug–drug interactions, and adverse drug reactions.
Campylobacter Infections With and Without Bacteremia: A Comparative Retrospective Population-Based Study
Authors: Sunnerhagen Torgny , Grenthe Rasmus , Kampmann Christian , Karlsson Söbirk Sara , Bläckberg Anna
Published: March 2024

Background

Bacteremia with species in the genus Campylobacter is rare, and knowledge of the disease course in comparison with Campylobacter enteritis is limited.

Methods

This is a retrospective population-based study. Episodes of Campylobacter bacteremia and Campylobacter enteritis with a concurrent negative blood culture result that occurred between 2015 and 2022 in southern Sweden were identified through the laboratory database. Medical records were reviewed, and clinical features between patients with bacteremic Campylobacter infections were compared with patients with Campylobacter spp found in feces.

Results

The study included 29 bacteremic infections with Campylobacter and 119 cases of Campylobacter spp found in feces. Patients with Campylobacter bacteremia were significantly older than those with enteritis (72 years [IQR, 58–62] vs 58 years [IQR, 33–67], P < .0001). Eleven patients with bacteremia developed sepsis within 48 hours from blood culturing, and no patient died within 30 days from hospital admission.

Conclusions

Campylobacter bacteremia is rare and occurs mainly in the elderly with comorbidities. In comparison with Campylobacter infections limited to the gastrointestinal tract, patients with bacteremic Campylobacter infections are older and seem more prone to develop sepsis. Classical gastroenteritis symptoms in bacteremic cases with Campylobacter may be absent.
Monthly Sulfadoxine-Pyrimethamine During Pregnancy Prevents Febrile Respiratory Illnesses: A Secondary Analysis of a Malaria Chemoprevention Trial in Uganda
Authors: Lee Jordan John , Kakuru Abel , Jacobson Karen B , Kamya Moses R , Kajubi Richard , Ranjit Anju , Gaw Stephanie L , Parsonnet Julie , Benjamin-Chung Jade , Dorsey Grant , Jagannathan Prasanna , Roh Michelle E
Published: March 2024

Background

Trials evaluating antimalarials for intermittent preventive treatment in pregnancy (IPTp) have shown that dihydroartemisinin-piperaquine (DP) is a more efficacious antimalarial than sulfadoxine-pyrimethamine (SP); however, SP is associated with higher birthweight, suggesting that SP demonstrates “nonmalarial” effects. Chemoprevention of nonmalarial febrile illnesses (NMFIs) was explored as a possible mechanism.

Methods

In this secondary analysis, we leveraged data from 654 pregnant Ugandan women without HIV infection who participated in a randomized controlled trial comparing monthly IPTp-SP with IPTp-DP. Women were enrolled between 12 and 20 gestational weeks and followed through delivery. NMFIs were measured by active and passive surveillance and defined by the absence of malaria parasitemia. We quantified associations among IPTp regimens, incident NMFIs, antibiotic prescriptions, and birthweight.

Results

Mean “birthweight for gestational age” Z scores were 0.189 points (95% CI, .045–.333) higher in women randomized to IPTp-SP vs IPTp-DP. Women randomized to IPTp-SP had fewer incident NMFIs (incidence rate ratio, 0.74; 95% CI, .58–.95), mainly respiratory NMFIs (incidence rate ratio, 0.69; 95% CI, .48–1.00), vs IPTp-DP. Counterintuitively, respiratory NMFI incidence was positively correlated with birthweight in multigravidae. In total 75% of respiratory NMFIs were treated with antibiotics. Although overall antibiotic prescriptions were similar between arms, for each antibiotic prescribed, “birthweight for gestational age” Z scores increased by 0.038 points (95% CI, .001–.074).

Conclusions

Monthly IPTp-SP was associated with reduced respiratory NMFI incidence, revealing a potential nonmalarial mechanism of SP and supporting current World Health Organization recommendations for IPTp-SP, even in areas with high-grade SP resistance. While maternal respiratory NMFIs are known risk factors of lower birthweight, most women in our study were presumptively treated with antibiotics, masking the potential benefit of SP on birthweight mediated through preventing respiratory NMFIs.
Long-Term Cochlear Implant Sound Processor Usage in Children with Single-Sided Deafness
Authors: Garcia-Matte Raimundo J. , O'Neil Luke M. , Chase Carl , Leeming Pia , Clack Rachel , Rodrigues Steve , Kuthubutheen Jafri
Published: March 2024

Objective

To assess cochlear implant (CI) sound processor usage over time in children with single-sided deafness (SSD) and identify factors influencing device use.

Study Design

Retrospective, chart review study.

Setting

Pediatric tertiary referral center.

Patients

Children with SSD who received CI between 2014 and 2020.

Outcome Measure

Primary outcome was average daily CI sound processor usage over follow-up.

Results

Fifteen children with SSD who underwent CI surgery were categorized based on age of diagnosis and surgery timing. Over an average of 4.3-year follow-up, patients averaged 4.6 hours/day of CI usage. Declining usage trends were noted over time, with the first 2 years postactivation showing higher rates. No significant usage differences emerged based on age, surgery timing, or hearing loss etiology.

Conclusions

Long-term usage decline necessitates further research into barriers and enablers for continued CI use in pediatric SSD cases.
Middle Ear Tophi: A Case Series of Two Unusual Lesions and a Report of Facial Weakness and Review of the Literature
Authors: Akella Deepthi S. , Ghezavati Alireza , Siddiqui Huma A. , Erbele Isaac D.
Published: March 2024

Objective

Tophaceous lesions of the middle ear from calcium pyrophosphate deposition disease (CPPD, or pseudogout) and gout are infrequently reported. Recognizing its characteristic findings will allow clinicians to accurately narrow the differential diagnosis of bony-appearing middle ear lesions and improve management.

Patients

Two consecutive cases of tophaceous middle ear lesions presenting to a tertiary care center between January 2021 and December 2021. Neither with previous rheumatologic history.

Interventions

Surgical excision of tophaceous middle ear lesions.

Main Outcome Measure

Improvements in facial weakness and conductive hearing loss.

Results

The first case was a 66-year-old gentleman with progressive conductive loss, ipsilateral progressive facial weakness over years, and an opaque, irregular-appearing tympanic membrane anterior to the malleus found to have CPPD on surgical pathology, with immediate postoperative improvement of facial function. The second was a 75-year-old gentleman with progressive conductive loss and similar appearing tympanic membrane as case 1, previously diagnosed with tympanosclerosis, found to have gout on surgical pathology. In both cases, the CT showed a heterogenous, bony-appearing lesion in the middle ear, and both tophaceous lesions were a of gritty, chalky consistency intraoperatively.

Conclusion

Tophaceous lesions of the middle ear are rare but have similar findings. Notably, the tympanic membrane can appear opaque and irregular, and the CT demonstrates a radiopaque, heterogeneous appearance. Facial weakness is an unusual finding. Specimens of suspected tophi must be sent to pathology without formalin for accurate diagnosis.
A Novel Hypobaric Perfusion Method to Remove Microthrombi in Kidney Grafts with Prolonged Circulatory Arrest: A Pilot Study on a Porcine Model
Authors: Kinoshita Yoshitaka , Iwai Satomi , Torai Shinji , Kurauchi Kanta , Yokoo Takashi , Kume Haruki , Tolba Rene , Kobayashi Eiji
Published: March 2024

Background.

Intragraft microthrombi prevent complete organ perfusion, thereby compromising the viability maintained by preservation solutions or machine perfusion. Herein, we developed and evaluated a hypobaric perfusion method for flushing microthrombi from kidney grafts with prolonged circulatory arrest in a porcine model.

Methods.

Porcine renal grafts with 1-h warm ischemia were flushed with heparin-containing perfusate in a normobaric environment (control group) or a hypobaric environment of −20 to −30 mm Hg (hypobaric perfusion group) for 10 min using a gravity drip from a 1-m height. Perfusion parameters, histological findings in ex vivo blood perfusion experiments (2 control and 4 hypobaric perfusion kidneys), and safety in allogeneic porcine transplantation experiments (1 donor to 2 recipients) were evaluated.

Results.

The −20 mm Hg hypobaric perfusion group exhibited greater maximal flow than the control group (20.4 versus 6.9 mL/min; P = 0.028). Histological evaluation following 3 h of static cold storage and 10 min ex vivo porcine whole-blood perfusion revealed statistically significant reductions in congestion and edema (1.5 versus 3, and 0.5 versus 4 on a 5-point scale, from 0 to 4; P = 0.014 and 0.006, respectively) in the medulla along with improved ischemia–reperfusion injury scores (4.0 versus 4.7 on a 6-point scale, from 0 to 5; P = 0.004) in the −20 mm Hg hypobaric perfusion group. Kidney grafts perfused under −30 mm Hg hypobaric environment followed by 3 h of static cold storage could be used for porcine allogeneic transplantation without any macroscopic damage to the graft, effect on intraoperative handling, or perioperative adverse events. Thus, the hypobaric perfusion method was considered safe.

Conclusions.

Perfusion in a hypobaric environment may prevent graft congestion, edema, and further reperfusion injury by flushing out erythrocytes occluding the medullary capillaries, improving marginal renal graft quality, and reducing the number of discarded grafts.