bluuebunny/crossref_metadata_2025 huggingface dataset:
Angular dependence of spin-flop transition in triangular lattice antiferromagnet Cu2(OH)3Br
Authors: Xiao T T , Ouyang Z W , Liu X C , Cao J J , Wang Z X , Tong W
Published: April 2022

We report angular dependence of spin-flop transition in triangular lattice antiferromagnet Cu2(OH)3Br by angle-dependent magnetization and ESR measurements. The results show that the antiferromagnetic easy magnetization axis is the diagonal direction (θ = 45°) of the ac
* plane, i.e., the orientation of Cu1 spins based on the magnetic structure (2020 Phys. Rev. Lett.
125 037204), whereas the spin-flop axis is the b axis. A phenomenological model is proposed to describe the angle-dependent spin-flop transitions. Based on this model, Cu1 spins are sensitive to external magnetic field, while Cu2 spins are robust against to the field, showing partial decoupling. The model is expected to be used in other uniaxial antiferromagnets with a more general easy axis and complex spin-flop transitions.
Radiobiological damage by space radiation: extension of the BIANCA model to heavy ions up to iron, and pilot application to cosmic ray exposure
Authors: Ramos Ricardo L , Embriaco Alessia , Carante Mario P , Ferrari Alfredo , Sala Paola , Vercesi Valerio , Ballarini Francesca
Published: April 2022

Space research seems to be object of a renewed interest, also considering that human missions to the Moon, and possibly Mars, are being planned. Among the risks affecting such missions, astronauts’ exposure to space radiation is a major concern. In this work, the question of the evaluation of biological damage by Galactic Cosmic Rays (GCR) was addressed by a biophysical model called BIophysical ANalysis of Cell death and chromosome Aberrations (BIANCA), which simulates the induction of cell death and chromosome aberrations by different ions. While previously BIANCA has been validated for calculating cell death along hadrontherapy beams up to oxygen, herein the approach was extended up to Fe ions. Specifically, experimental survival curves available in literature for V79 cells irradiated by Si-, Ne-, Ar- and Fe-ions were reproduced, and a reference radiobiological database describing V79 cell survival as a function of ion type (1 ⩽ Z ⩽ 26), energy and dose was constructed. Analogous databases were generated for Chinese hamster ovary hamster cells and human skin fibroblasts, finding good agreement between simulations and data. Concerning chromosome aberrations, which are regarded as radiation risk biomarkers, dicentric data in human lymphocytes irradiated by heavy ions up to iron were reproduced, and a radiobiological database allowing calculation of lymphocyte dicentric yields as a function of dose, ion type (1 ⩽ Z ⩽ 26) and energy was constructed. Following interface between BIANCA and the FLUKA Monte Carlo transport code, a feasibility study was performed to calculate the relative biological effectiveness (RBE) of different GCR spectrum components, for both dicentrics and cell death. Fe-ions, although representing only 10% of the total absorbed dose, were found to be responsible for about 35%–40% of the RBE-weighted dose. Interestingly, the RBE for dicentrics was higher than that for cell survival. More generally, this work shows that BIANCA can calculate RBE values for cell death and lymphocyte dicentrics not only for ion therapy, but also for space radiation.
Multi-nanocavities and multi-defects synergetic enhancement for the electromagnetic absorption of the rGO-NG film
Authors: Yu Yue , Zhao Yifang , Dai Yongqiang , Su Yu , Liao Bing , Pang Hao
Published: April 2022

Dielectric loss is an important way to eliminate electromagnetic pollution. In order to achieve high dielectric loss, a graphene film reduced graphene oxide-N doped graphene (rGO-NG) was constructed from graphene oxide-Ni@polydopamine (GO-Ni@PDA) via the in situ synthesis of hollow graphene spheres between graphene sheets. This in situ was achieved by means of electrostatic self-assembly and metal-catalyzed crystallization. Owing to the synergetic effect of multi-nanocavities and multi-defects, the prepared rGO-NG film shows an average shielding effectiveness (SE) of 50.0 dB in the range of 8.2–12.4 GHz with a thickness of 12.2 μm, and the SE reflection is only 7.3 dB on average. It also exhibits an average dielectric loss tangent (tan δ) of 23.1, which is 26 and 105 times higher than those of rGO and rGO-Ni, respectively. This work provides a simple but effective route to develop high performance graphene-based materials for application as an electromagnetic interference shielding film in today’s electronic devices.
A comparative investigation of the optical properties of polar and semipolar GaN epi-films grown by metalorganic chemical vapor deposition
Authors: Lu Haixia , Wang Lianshan , Liu Yao , Zhang Shuping , Yang Yanlian , Saravade Vishal , Feng Zhe Chuan , Klein Benjamin , Ferguson Ian T , Wan Lingyu , Sun Wenhong
Published: April 2022

We report on the structural and optical properties of polar gallium nitride on c-plane sapphire substrates and semi-polar (11–22) GaN films on m-plane sapphire substrates by metalorganic chemical vapor deposition. Polar GaN on c-plane sapphire and semi-polar GaN on m-plane sapphire both show good crystal quality, luminescence, absorption, and Raman characteristics. GaN on c-place sapphire shows a high crystal quality as compared to GaN on m-plane sapphire. Surface roughness of polar GaN is lesser than semi-polar GaN. The biaxial structural stress in GaN switches from compressive to tensile as the temperature is increased. This stress-switch temperature is higher in GaN/c-plane than GaN/m-plane. GaN in polar and semi-polar orientation shows ultraviolet emissions but yellow-emissions are only observed in GaN/c-plane sapphire. Raman spectroscopy-related oscillations show systematic variations with temperature in both GaN configurations (polar and semi-polar). This work provides a framework of characterizations for GaN with different crystal polarities. It contributes towards identifying suitable crystal growth mechanisms based on the application and requirements for doping (In, Al, etc), crystal quality, emission, absorption, and photonic oscillations.
Performance of Fe–Ga alloy rotational vibration energy harvester with centrifugal softening
Authors: Liu Huifang , Dong Weiwei , Sun Xingwei , Wang Shuqing , Li Wencheng
Published: April 2022

With the development of vibration energy harvesting, sensor nodes for wireless monitoring are being increasingly powered by harvesting vibrations in rotating environments such as car tires and fan blades. Considering the diverse installation positions of vibration energy harvesters on rotating carriers, the centrifugal forces of the cantilever beams exhibit remarkable differences during rotation. Crucial factors for the performance of vibration energy harvesting include the deformation of the harvester cantilever beam, which is affected by the centrifugal force, and the influence of the pre-magnetization field on the Villari effect of specific alloys. We propose a rotational vibration energy harvester based on an Fe–Ga alloy and establish a mathematical model for magnetostrictive vibration energy harvesting by leveraging centrifugal softening. In addition, we perform a systematic theoretical analysis of the factors influencing the harvester performance considering centrifugal softening, rotation radius, and arrangement of the pre-magnetization field. The theoretical findings are verified on a prototype, and the system characteristics are investigated experimentally. The maximum output voltage reaches 3.36 V, and the energy harvesting efficiency reaches 22.86% when the harvester undergoes rotation at 330 r min−1. Moreover, the harvester is applied in a low-power temperature sensor for real-time temperature monitoring, indicating the validity and applicability of the proposed rotational vibration energy harvester. The results demonstrate that an appropriate use of the centrifugal softening and the pre-magnetization field can enhance the energy harvesting efficiency of a harvester operating at a low rotational frequency.
Superconducting microwave resonators with non-centrosymmetric nonlinearity
Authors: Khabipov M , Gaydamachenko V , Kissling C , Dolata R , Zorin A B
Published: April 2022

We investigated both theoretically and experimentally open-ended coplanar waveguide resonators with rf SQUIDs embedded in the central conductor at different positions. These rf SQUIDs can be tuned by an external magnetic field and thus may exhibit the non-centrosymmetric nonlinearity ofχ(2)type with suppressed Kerr nonlinearity. We demonstrated that this nonlinearity allows for efficient mixing ofλ/2andλmodes in the cavity and thus enables various parametric effects with three wave mixing. These effects are the second harmonic generation, the halftone generation, the parametric amplification in both degenerate and non-degenerate regimes and deamplification in degenerate regime.
Unconventional steady states and topological phases in an open two-level non-Hermitian system
Authors: Xu Jian , Guo Youneng
Published: April 2022

Decoherence and non-Hermiticity are two different effects of the open quantum systems. Both of them have triggered many interesting phenomena. In this paper, we theoretically study an open two-level non-Hermitian system coupling to a dissipative environment by solving the vectorized Lindblad equation. This scheme provides us a powerful framework to address widespread open systems with gain, loss and dissipation. Our results show that there exist a new class of exceptional points and steady states due to the interplay between non-Hermiticity and decoherence. Furthermore, we also demonstrate a new-type topological properties of eigenstates with zero real-part of eigenvalues (Re[λ] = 0) which are corresponding to Fermi arcs. It is revealed that the phases of eigenstates located in Fermi arcs regime have a topological phase |π/2| which is totally unaffected by the dissipative environment. Our results provide a promising approach for further uncovering and understanding the intriguing properties of non-Hermitian open systems.
Wave mode computing method using the step-split Padé parabolic equation
Authors: Xu Chuan-Xiu , Zheng Guang-Ying
Published: April 2022

Models based on a parabolic equation (PE) can accurately predict sound propagation problems in range-dependent ocean waveguides. Consequently, this method has developed rapidly in recent years. Compared with normal mode theory, PE focuses on numerical calculation, which is difficult to use in the mode domain analysis of sound propagation, such as the calculation of mode phase velocity and group velocity. To broaden the capability of PE models in analyzing the underwater sound field, a wave mode calculation method based on PE is proposed in this study. Step-split Padé PE recursive matrix equations are combined to obtain a propagation matrix. Then, the eigenvalue decomposition technique is applied to the matrix to extract sound mode eigenvalues and eigenfunctions. Numerical experiments on some typical waveguides are performed to test the accuracy and flexibility of the new method. Discussions on different orders of Padé approximant demonstrate angle limitations in PE and the missing root problem is also discussed to prove the advantage of the new method. The PE mode method can be expanded in the future to solve smooth wave modes in ocean waveguides, including fluctuating boundaries and sound speed profiles.
Probing subcycle spectral structures and dynamics of high-order harmonic generation in crystals
Authors: Lin Long , Jia Tong-Gang , Wang Zhi-Bin , Li Peng-Cheng
Published: April 2022

Subcycle spectral structures and dynamics of high-order harmonic generation (HHG) processes of atoms and molecules driven by intense laser fields on the attosecond time scale have been originally studied theoretically and experimentally. However, the time scale of HHG dynamics in crystals is in the order of sub-femtosecond, and the carrier dynamics of HHG in crystals driven by subcycle laser pulses are largely unexplored. Here we perform a theoretical study of subcycle structures, spectra, and dynamics of HHG of crystals in mid-infrared laser fields subject to excitation by a subcycle laser pulse with a time delay. The HHG spectra as a function of time delay between two laser fields are calculated by using a single-band model for the intra-band carrier dynamics in crystal momentum space and by solving the time-dependent Schrödinger equation in velocity gauge for the treatment of multi-band crystal systems. The results exhibit a complex time-delay-dependent oscillatory pattern, and the enhancement and suppression of the HHG related to subcycle pulse are observed at the given time delay in either single-band or multi-band crystal systems. To understand oscillation structures with respect to the dependence for the subcycle laser fields, the time-frequency characteristics of the HHG as well as the probability density distribution of the radiation are analyzed in detail.
New designed helical resonator to improve measurement accuracy of magic radio frequency
Authors: Guo Tian , Liu Peiliang , Lee Chaohong
Published: April 2022

Based upon the new designed helical resonator, the resonant radio frequency (RF) for trapping ions can be consecutively adjusted in a large range (about 12 MHz to 29 MHz) with high Q-factors (above 300). We analyze the helical resonator with a lumped element circuit model and find that the theoretical results fit well with the experimental data. With our resonator system, the resonant frequency near magic RF frequency (where the scalar Stark shift and the second-order Doppler shift due to excess micromotion cancel each other) can be continuously changed at kHz level. For 88Sr+ ion, compared to earlier results, the measurement accuracy of magic RF frequency can be improved by an order of magnitude upon rough calculation, and therefore the net micromotion frequency shifts can be further reduced. Also, the differential static scalar polarizability Δα
0 of clock transition can be experimentally measured more accurately.
Lateral characteristics improvements of DBR laser diode with tapered Bragg grating
Authors: Wang Qi-Qi , Xu Li , Fan Jie , Wang Hai-Zhu , Ma Xiao-Hui
Published: April 2022

Broad area semiconductor laser (BAL) has poor lateral beam quality due to lateral mode competition, which limits its application as a high-power optical source. In this work, the distributed Bragg reflector laser diode with tapered grating (TDBR-LD) is studied. By changing the lateral width, the tapered grating increases the loss of high-order lateral modes, thus improving the lateral characteristics of the laser diode. The measuring results show that the TDBR-LD can achieve a single-lobe output under 0.9 A. In contrast to the straight distributed Bragg reflector laser diode (SDBR-LD), the lateral far field divergence of TDBR-LD is measured to be 5.23° at 1 A, representing a 17% decline. The linewidth of TDBR-LD is 0.4 nm at 0.2 A, which is reduced by nearly 43% in comparison with that of SDBR-LD. Meanwhile, both of the devices have a maximum output power value of approximate 470 mW.
Development of data correction for the 1M Large Pixel Detector at the EuXFEL
Authors: Wheater R.M. , Hart M.D. , Veale M.C. , Wilson M.D. , Doblas-Jiménez D. , Turcato M. , Milne C. , Yousef H. , Khakhulin D.
Published: April 2022

We present the development of a gain correction process for the Large Pixel Detector (LPD) developed by the Science and Technology Facilities Council (STFC) for the Femtosecond X-Ray Experiment (FXE) instrument based at the European X-ray Free Electron Laser (EuXFEL). LPD operates at 4.5 MHz as necessitated by EuXFEL's pulse timing structure and has a large dynamic range capturing a maximum of 105 photons/pixel @ 12 keV. Experiments at FXE require highly accurate measurements of relative changes in X-ray scattering intensity on the MHz timescale making a correction bringing LPD pixel outputs in line against a common axis essential to understanding experimental results. To facilitate the operational needs of LPD at FXE more than 1.5 billion correction coefficients are required, with corrections generated on a per pixel, per memory cell and per gain stage basis. By comparing output LPD signals to an independent reference diode a linear gain correction has been developed and applied to LPD data. Improvements in image quality have been quantified using the standard deviation in the measured intensity per pixel for a given radius from the beam centre. Improvements to detector uniformity of up to 30.0% are demonstrated in the medium gain stage and 15.9% in the high gain stage. This paper presents an in-depth view of the gain correction development process and further results.
SiC and Ion collectors as diagnostics of laser-generated plasma at intensity
of 1010W/cm2
Authors: Torrisi L. , Torrisi A.
Published: April 2022

Characterization of non-equilibrium plasma by 1010 W/cm2 IR pulsed laser irradiating metallic targets in a vacuum, has been performed employing a Faraday cup as an ion collector (IC) and a SiC interdigitated detector, connected in time-of-flight (TOF) configuration.

Both detectors reveal the emitted fast UV and the slower plasma ions. The measure of energy of ions and photons has been evaluated using the TOF spectra and thin absorbers.

The fast semiconductor response and its high detection efficiency give a good benchmark measurement of radiations at low energy
emitted by plasma generated by ns laser pulses. Thanks to the IC detector response it is possible to evaluate the ion current emitted from the plasma. The simultaneous use of the two detectors allows to monitor and evaluate different plasma parameters, such as the time emission, the temperature, the maximum particle energy and charge state, and others.
Multi-Hamiltonian structure of the epidemics model accounting for vaccinations and a suitable test for the accuracy of its numerical solvers
Authors: Haas F , Kröger M , Schlickeiser R
Published: April 2022

We derive a generalized Hamiltonian formalism for a modified susceptible–infectious–recovered/removed (SIR) epidemic model taking into account the population V of vaccinated persons. The resulting SIRV model is shown to admit three possible functionally independent Hamiltonians and hence three associated Poisson structures. The reduced case of vanishing vaccinated sector shows a complete correspondence with the known Poisson structures of the SIR model. The SIRV model is shown to be expressible as an almost Nambu system, except for a scale factor function breaking the divergenceless property. In the autonomous case with time-independent stationary ratios k and b, the SIRV model is shown to be a maximally super-integrable system. For this case we test the accuracy of numerical schemes that are suited to solve the stiff set of SIRV differential equations.
A critical review on mechanically alloyed high entropy alloys: processing challenges and properties
Authors: Kumar Akshay , Singh Alok , Suhane Amit
Published: April 2022

High entropy alloys are an innovative class of materials for a wide range of industrial applications due to their competitive properties such as improved mechanical properties, superior wear resistance characteristics, and excellent corrosion behavior, which are widely desired for a variety of applications considering several attributes such as economical, eco-friendly and safety. Thus, the quest for high-performance materials with exceptional properties is an unfading research topic for researchers, academia, and metallurgical scientists. HEA presents a novel alloy design idea focused on multi principal elements, a huge compositional space, and more opportunities to develop diverse alloys with exceptional properties. As universally acknowledged, the immense potential in compositions, microstructures, and properties has sparked a great interest in this field. Researchers primarily focused on equimolar HEAs, but the precedent eventually shifted to non-equimolar alloys. As the investigation over HEAs progressed, four core effects were identified as the most important aspects in enabling the distinct characteristics. Mechanical alloying (MA), followed by the sintering approach, has piqued the interest of all researchers focusing on HEA development. As a result, the main intent of this study is to examine mechanically alloyed HEAs critically for mechanical properties, tribological behavior, corrosion behavior, and functional properties. Furthermore, the predominant challenges and their conceivable prospects are also deliberated that offer novelty to this review article.
The mechanism study of low-pressure air plasma cleaning on large-aperture optical surface unraveled by experiment and reactive molecular dynamics simulation
Authors: LI Yuhai , BAI Qingshun , GUAN Yuheng , LIU Hao , ZHANG Peng , BATELIBIEKE Buerlike , SHEN Rongqi , LU Lihua , YUAN Xiaodong , MIAO Xinxiang , HAN Wei , YAO Caizhen
Published: April 2022

Low-pressure air plasma cleaning is an effective method for removing organic contaminants on large-aperture optical components in situ in the inertial confinement fusion facility. Chemical reactions play a significant role in plasma cleaning, which is a complex process involving abundant bond cleavage and species generation. In this work, experiments and reactive molecular dynamics simulations were carried out to unravel the reaction mechanism between the benchmark organic contaminants of dibutyl phthalate and air plasma. The optical emission spectroscopy was used to study the overall evolution behaviors of excited molecular species and radical signals from air plasma as a reference to simulations. Detailed reaction pathways were revealed and characterized, and specific intermediate radicals and products were analyzed during experiments and simulation. The reactive species in the air plasma, such as O, HO2 and O3 radicals, played a crucial role in cleaving organic molecular structures. Together, our findings provide an atomic-level understanding of complex reaction processes of low-pressure air plasma cleaning mechanisms and are essential for its application in industrial plasma cleaning.
Improving quantum state detection with adaptive sequential observations
Authors: Geller Shawn , Cole Daniel C , Glancy Scott , Knill Emanuel
Published: April 2022

For many quantum systems intended for information processing, one detects the logical state of a qubit by integrating a continuously observed quantity over time. For example, ion and atom qubits are typically measured by driving a cycling transition and counting the number of photons observed from the resulting fluorescence. Instead of recording only the total observed count in a fixed time interval, one can observe the photon arrival times and get a state detection advantage by using the temporal structure in a model such as a hidden Markov model. We study what further advantage may be achieved by applying pulses to adaptively transform the state during the observation. We give a three-state example where adaptively chosen transformations yield a clear advantage, and we compare performances on an ion example, where we see improvements in some regimes. We provide a software package that can be used for exploration of temporally resolved strategies with and without adaptively chosen transformations.
Metamorphosis: The American Journal of Hygiene Becomes the American Journal of Epidemiology
Authors: Nathanson Neal
Published: April 2022

In this brief Commentary, Neal Nathanson recounts his memories of the metamorphosis of the American Journal of Hygiene into the American Journal of Epidemiology, and his subsequent service as the Editor-in-Chief from 1964 to 1979.
scCODE: an R package for data-specific differentially expressed gene detection on single-cell RNA-sequencing data
Authors: Zou Jiawei , Deng Fulan , Wang Miaochen , Zhang Zhen , Liu Zheqi , Zhang Xiaobin , Hua Rong , Chen Ke , Zou Xin , Hao Jie
Published: April 2022

Differential expression (DE) gene detection in single-cell ribonucleic acid (RNA)-sequencing (scRNA-seq) data is a key step to understand the biological question investigated. Filtering genes is suggested to improve the performance of DE methods, but the influence of filtering genes has not been demonstrated. Furthermore, the optimal methods for different scRNA-seq datasets are divergent, and different datasets should benefit from data-specific DE gene detection strategies. However, existing tools did not take gene filtering into consideration. There is a lack of metrics for evaluating the optimal method on experimental datasets. Based on two new metrics, we propose single-cell Consensus Optimization of Differentially Expressed gene detection, an R package to automatically optimize DE gene detection for each experimental scRNA-seq dataset.
Revisiting benchmark study for response to methodological critiques of ‘Evaluation of phenotype-driven gene prioritization methods for Mendelian diseases’
Authors: Yuan Xiao , Zhang Peng
Published: April 2022

Evaluation of phenotype-driven gene prioritization approaches for Mendelian diseases could facilitate the software development and method selection for the workflow configuration and clinical practice. In our original article, the performance of 10 well-recognized causal-gene prioritization methods was benchmarked using 305 cases from the deciphering developmental disorders (DDD) project and 209 in-house cases via a relatively unbiased methodology. The evaluation results showed that LIRICAL and AMELIE were two of the best methods in our benchmark experiments, and the possible integrative approach of these two methods may enhance the diagnostic efficiency. However, some methodological critiques were raised by the authors of Exomiser and PhenIX, so we revisited our benchmarking studies to answer their comments in this letter.
Relative Vaccine Effectiveness of a Severe Acute Respiratory Syndrome Coronavirus 2 Messenger RNA Vaccine Booster Dose Against the Omicron Variant
Authors: Butt Adeel A , Talisa Victor B , Shaikh Obaid S , Omer Saad B , Mayr Florian B
Published: April 2022

Background

The current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines may be less effective against the Omicron variant than against earlier variants. With recent resurgence of SARS-CoV-2 cases, the role of booster doses of the vaccine needs to be highlighted.

Methods

Using a retrospective cohort study design emulating a target trial, we determined the relative vaccine effectiveness (RVE) of a homologous booster dose of a SARS-CoV-2 messenger RNA (mRNA) vaccine compared with the primary vaccine series alone in preventing infection, hospitalization, and intensive care unit admission, and death in the Department of Veterans Affairs healthcare system in the United States. Among infection-free survivors who received 2 doses of a mRNA vaccine before 30 April 2021, we identified those who received a booster between 22 September and 25 December 2021 and matched them 1:1 with individuals who did not receive a booster.

Results

Among 2 384 272 previously uninfected persons with 2 doses of an mRNA vaccine by 30 April 2021, we identified 462 950 booster recipients between 22 September and 25 December 2021, who were matched 1:1 with non–booster recipients. The RVE (95% confidence interval) was 19% (17%–22%) for confirmed infection, 52% (46%–57%) for hospitalization, and 83% (65%–92%) for intensive care unit admission or death. Recipients of the mRNA-1273 vaccine had a lower cumulative incidence of infections and hospitalizations than recipients of the BNT162b2 vaccine (log-rank P <.001 for both comparisons).

Conclusions

While the RVE of SARS-CoV-2 mRNA booster vaccine dose in preventing infection against the Omicron variant is low, it is substantial in preventing hospitalization and high in preventing the most severe/critical disease.
A wealth tax on corporations’ stock
Authors: Saez Emmanuel , Zucman Gabriel
Published: April 2022

We propose to institute a new tax on corporations’ stock shares for all publicly listed companies and large private companies headquartered in G20 countries. Each of these companies would have to pay 0.2% of the value of its stock in taxes each year. As the G20 stock market capitalization is around 100% of world GDP, the tax would raise approximately 0.2% of world GDP in revenue. Because stock ownership is highly concentrated among the rich, this tax would be progressive. The tax could be paid in kind by corporations (by issuing new stock) so that the tax does not raise liquidity issue nor affect business operations. In today’s globalized and fast-moving world, companies can become enormously valuable once they establish market power, even before they start making large profits (e.g., Amazon and Tesla). This tax would make them start paying taxes sooner than standard income taxes.
Mortality in COVID-19 among women on hormone replacement therapy: a retrospective cohort study
Authors: Dambha-Miller Hajira , Hinton William , Wilcox Christopher R , Joy Mark , Feher Michael , de Lusignan Simon
Published: April 2022

Background

Limited recent observational data have suggested that there may be a protective effect of oestrogen on the severity of COVID-19 disease. Our aim was to investigate the association between hormone replacement therapy (HRT) or combined oral contraceptive pill (COCP) use and the likelihood of death in women with COVID-19.

Methods

We undertook a retrospective cohort study using routinely collected computerized medical records from the Oxford-Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC) primary care database. We identified a cohort of 1,863,478 women over 18 years of age from 465 general practices in England. Mixed-effects logistic regression models were used to quantify the association between HRT or COCP use and all-cause mortality among women diagnosed with confirmed or suspected COVID-19 in unadjusted and adjusted models.

Results

There were 5,451 COVID-19 cases within the cohort. HRT was associated with a reduction in all-cause mortality in COVID-19 (adjusted OR 0.22, 95% CI 0.05 to 0.94). There were no reported events for all-cause mortality in women prescribed COCPs. This prevented further examination of the impact of COCP.

Conclusions

We found that HRT prescription within 6 months of a recorded diagnosis of COVID-19 infection was associated with a reduction in all-cause mortality. Further work is needed in larger cohorts to examine the association of COCP in COVID-19, and to further investigate the hypothesis that oestrogens may contribute a protective effect against COVID-19 severity.
Engineering the polyphenolic biosynthetic pathway stimulates metabolic and molecular changes during fruit ripening in “Bronze” tomato
Authors: Scarano Aurelia , Gerardi Carmela , Sommella Eduardo , Campiglia Pietro , Chieppa Marcello , Butelli Eugenio , Santino Angelo
Published: April 2022

The metabolic engineered Bronze tomato line is characterized by the constitutive over-expression of the VvStSy gene encoding a structural protein responsible for the stilbenoids biosynthesis and the fruit-specific over-expression of AmDel/Rosea1 and AtMYB12 genes encoding transcription factors that activate the polyphenol biosynthetic pathway. This tomato line is known for the increased levels of polyphenols in ripe fruits and for beneficial health promoting antioxidant and anti-inflammatory effects. In this study we analyzed the transcriptional and metabolic profiling in mature green, breaker, orange and ripe fruits compared to the normal tomato counterparts during ripening, to unravel the effect of regulatory and structural transgenes on metabolic fluxes of primary and secondary metabolisms. Our results showed that the shikimate synthase (SK) gene was up-regulated in the Bronze fruit, and the transcriptional activation is consistent with the metabolic changes observed throughout fruit ripening. These results paralleled with a reduced level of simple sugars and malate, highlighting the consumption of primary metabolites to favor secondary metabolites production and accumulation. Finally, carotenoids quantification revealed a change in the lycopene/β-carotene ratio in the Bronze fruit as a consequence of significant lower level of the first and higher levels of the latter. The high polyphenols and β-carotene content displayed by the Bronze fruit at the later stages of fruit ripening renders this line an interesting model to study the additive or synergic effects of these phyto-chemicals in the prevention of human pathologies.
Identification of WRKY transcription factors involved in regulating the biosynthesis of the anti-cancer drug camptothecin in Ophiorrhiza pumila
Authors: Wang Can , Hao Xiaolong , Wang Yao , Maoz Itay , Zhou Wei , Zhou Zhigang , Kai Guoyin
Published: April 2022

Camptothecin is a chemotherapeutic drug widely used to treat various cancers. Ophiorrhiza pumila is an ideal plant model for the study of camptothecin production, with various advantages for studying camptothecin biosynthesis and regulation. The DNA-binding WRKY transcription factors have a key regulatory role in secondary metabolite biosynthesis in plants. However, little is currently known about their involvement in camptothecin biosynthesis in O. pumila. We identified 46 OpWRKY genes unevenly distributed on the 11 chromosomes of O. pumila. Phylogenetic and multiple sequence alignment analyses divided the OpWRKY proteins into three subfamilies. Based on spatial expression and co-expression, we targeted the candidate gene OpWRKY6. Overexpression of OpWRKY6 significantly reduced the accumulation of camptothecin compared with the control. Conversely, camptothecin accumulation increased in OpWRKY6 knockout lines. Further biochemical assays showed that OpWRKY6 negatively regulates camptothecin biosynthesis from both the iridoid and shikimate pathways by directly downregulating the gene expression of OpGES, Op10HGO, Op7DLH, and OpTDC. Our data provide direct evidence for the involvement of WRKYs in the regulation of camptothecin biosynthesis and offer valuable information for enriching the production of camptothecin in plant systems.
Bladder lymphoepithelioma-like carcinoma: a case report
Authors: Rahoui Moez , Ouanes Yassine , Chaker Kays , Dali Kheireddine Mrad , Bibi Mokhtar , Sellami Ahmed , Rhouma Sami Ben , Nouira Yassine
Published: April 2022

Bladder lymphoepithelioma-like carcinoma is a rare entity. It represents a particular variant of urothelial carcinoma characterized by an important infiltrating power. Therapeutic management of this cancer is not codified. Surgery associated with chemotherapy seems to be the best therapeutic option. Few cases of this tumor have been reported in the literature. We report a case of bladder lymphoepithelioma-like carcinoma in a 52-year-old patient who presented with gross hematuria and discusses difficulties of diagnostic and treatment.
Delayed brain metastasis after 17-years from papillary thyroid cancer without local recurrence: case report and literature review
Authors: Knight James , Kingham Matthew , Price Sally-Ann , Bodi Istvan , Lavrador Jose Pedro
Published: April 2022

Papillary thyroid carcinoma (PTC) is the most common malignancy originating from the thyroid, with a good overall prognosis. However, distant metastasis of such lesions is very rare, with the brain being an incredibly uncommon site for secondary spread. The authors report a case of PTC brain metastasis 17-years after successful treatment of the primary malignancy, with no local or locoregional recurrence. Initial diagnostic uncertainty necessitated the involvement of a multidisciplinary team, and eventually the patient underwent image-guided gross surgical resection with intraoperative neuromonitoring (IOMN).
Evaluation of Prescribing Patterns Following Surgical Procedures in Opioid Naïve Patients at a Veterans Affairs Teaching Hospital
Authors: Chitwood Caleb , Haug Karlie L , Wenthur Cody , Gillis Carly , Maloney James D , Johnson Diane
Published: April 2022

Objectives

To evaluate facility postoperative opioid prescribing patterns in comparison to published guidelines and adherence to opioid safety mandates.

Methods

This quality analysis was performed between November 2019 and March 2020. Patients were identified to have been opioid naïve prior to receiving a new opioid prescription postoperatively during the study period. Patient charts were reviewed, and patients were contacted to collect desired data. Statistical analysis was performed to evaluate distributions of morphine equivalent daily dose and opioid day supply prescribed across study subpopulations.

Results

Ninety-four of 100 prescriptions evaluated were determined to be within quantity or duration recommendations of the selected guideline. Statistical analysis found no significantly different distributions between the duration and quantity of opioid prescribed at discharge and patient-specific risk factors. Forty-eight patients did not use the entire quantity of the initial opioid prescription dispensed. Of those patients, 26 still had opioids within the home. Opioid risk review documentation was completed in 19 of 65 patients indicated for documentation.

Conclusion

Most opioid prescriptions provided within the study period aligned with recommendations from author-selected guidelines. However, a review of risk prior to opioid prescribing frequently was not performed. The number of patients utilizing less than 50% of prescribed opioids, and few refills indicate that reductions in opioids prescribed would improve safety for both patients and the surrounding community without increasing the risk for the under-treatment of postoperative pain. Improved prescribing habits and patient safety will be targeted through provider education regarding risk review documentation in opioid naïve patients.
Reliable event detection for Taylor methods in astrodynamics
Authors: Biscani Francesco , Izzo Dario
Published: April 2022

We present a novel approach for the detection of events in systems of ordinary differential equations. The new method combines the unique features of Taylor integrators with state-of-the-art polynomial root finding techniques to yield a novel algorithm, ensuring strong event detection guarantees at a modest computational overhead. Detailed tests and benchmarks focused on problems in astrodynamics and celestial mechanics (such as collisional N-body systems, spacecraft dynamics around irregular bodies accounting for eclipses, computation of Poincaré sections, etc.) show how our approach is superior in both performance and detection accuracy to strategies commonly employed in modern numerical integration works. The new algorithm is available in our open source Taylor integration package heyoka.
The cosmic-ray staircase: the outcome of the cosmic-ray acoustic instability
Authors: Tsung Tsun Hin Navin , Oh S Peng , Jiang Yan-Fei
Published: April 2022

Recently, cosmic rays (CRs) have emerged as a leading candidate for driving galactic winds. Small-scale processes can dramatically affect global wind properties. We run two-moment simulations of CR streaming to study how sound waves are driven unstable by phase-shifted CR forces and CR heating. We verify linear theory growth rates. As the sound waves grow non-linear, they steepen into a quasi-periodic series of propagating shocks; the density jumps at shocks create CR bottlenecks. The depth of a propagating bottleneck depends on both the density jump and its velocity; ΔPc is smaller for rapidly moving bottlenecks. A series of bottlenecks creates a CR staircase structure, which can be understood from a convex hull construction. The system reaches a steady state between growth of new perturbations, and stair mergers. CRs are decoupled at plateaus, but exert intense forces and heating at stair jumps. The absence of CR heating at plateaus leads to cooling, strong gas pressure gradients and further shocks. If bottlenecks are stationary, they can drastically modify global flows; if their propagation times are comparable to dynamical times, their effects on global momentum and energy transfer are modest. The CR acoustic instability is likely relevant in thermal interfaces between cold and hot gas, as well as galactic winds. Similar to increased opacity in radiative flows, the build-up of CR pressure due to bottlenecks can significantly increase mass outflow rates, by up to an order of magnitude. It seeds unusual forms of thermal instability, and the shocks could have distinct observational signatures, on ∼kpc scales.
Can a binary neutron star merger in the vicinity of a supermassive black hole enable a detection of a post-merger gravitational wave signal?
Authors: Vijaykumar Aditya , Kapadia Shasvath J , Ajith Parameswaran
Published: April 2022

The post-merger gravitational-wave (GW) signal of a binary neutron star (BNS) merger is expected to contain valuable information that could shed light on the equation of state (EOS) of NSs, the properties of the matter produced during the merger, as well as the nature of any potential intermediate merger product such as hypermassive or supramassive NSs. However, the post-merger lies in the high frequency regime (≳1000 Hz) where current LIGO-Virgo detectors are insensitive. While proposed detectors such as NEMO, Cosmic Explorer and Einstein Telescope could potentially detect the post-merger for BNSs within $\mathcal {O}(10~\mathrm{Mpc})$, such events are likely to be rare. In this work, we speculate on the possibility of detecting the post-merger from BNSs coalescing in the vicinity of supermassive black holes (SMBHs). The redshift produced by the gravitational field of the SMBH, as well as the BNS’s proper motion around the SMBH, could effectively ‘stretch’ the post-merger signal into the band of the detectors. We demonstrate, using a phenomenological model, that such BNS coalescences would enable constraints on the peak of the post-merger signal that would otherwise have not been possible, provided the degree of redshifting due to the SMBH can be independently acquired. Further, using numerical simulations of binary neutron stars, we show how such mergers would improve EOS model selection using the post-merger signal. We discuss the mechanisms that might deliver such events and the limitations of this work.
Centrifugal breakout reconnection as the electron acceleration mechanism powering the radio magnetospheres of early-type stars
Authors: Owocki S P , Shultz M E , ud-Doula A , Chandra P , Das B , Leto P
Published: April 2022

Magnetic B-stars often exhibit circularly polarized radio emission thought to arise from gyrosynchrotron emission by energetic electrons trapped in the circumstellar magnetosphere. Recent empirical analyses show that the onset and strength of the observed radio emission scale with both the magnetic field strength and the stellar rotation rate. This challenges the existing paradigm that the energetic electrons are accelerated in the current sheet between opposite-polarity field lines in the outer regions of magnetized stellar winds, which includes no role for stellar rotation. Building on recent success in explaining a similar rotation-field dependence of H α line emission in terms of a model in which magnetospheric density is regulated by centrifugal breakout (CBO), we examine here the potential role of the associated CBO-driven magnetic reconnection in accelerating the electrons that emit the observed gyrosynchrotron radio. We show in particular that the theoretical scalings for energy production by CBO reconnection match well the empirical trends for observed radio luminosity, with a suitably small, nearly constant conversion efficiency ϵ ≈ 10−8. We summarize the distinct advantages of our CBO scalings over previous associations with an electromotive force, and discuss the potential implications of CBO processes for X-rays and other observed characteristics of rotating magnetic B-stars with centrifugal magnetospheres.
Review of nutritional approaches to fibromyalgia
Authors: Kadayifci Fatma Z , Bradley Madelyn J , Onat Ahmet M , Shi Hai Ning , Zheng Shasha
Published: April 2022

Context

A multidisciplinary approach has been suggested to be the optimal form of treatment of fibromyalgia (FM). A research focus on nutritional therapy has developed in recent years, and this approach has been more frequently integrated into the recovery plan of patients with FM.

Objectives

The interaction between the nutritional status and health of patients with FM is highlighted in this review, and possible dietary approaches to ameliorating the disease’s effects are discussed.

Data sources

FM research studies containing a nutrition or diet focus with a publication date between 2000 and 2021 were scanned broadly through a computerized search of the MEDLINE, PubMed, and Web of Science databases.

Study selection

Studies that included the following criteria were eligible for inclusion: (1) original research and case studies that evaluated obesity and nutritional approaches as a therapeutic intervention for FM, and (2) patients older than 18 years who were diagnosed withFM according to the 1990 American College of Rheumatology criteria.

Data Extraction

Interventions included nutritional supplementation, nutrient- and obesity-related blood analyses, prescribed diets, body mass index or obesity and quality-of-life assessments, weight reduction, food-additive elimination, and evaluation of food perception and food sensitivity.

Results

After the literature search, 36 studies (N = 5142 individuals) were identified as relevant, and their full texts were assessed for inclusion in the review. Conditions such as obesity, food allergies, nutritional deficiencies, and food additives were revealed to be risk factors that correlated with complications of FM. Several studies showed beneficial effects for patients with FM of high-antioxidant, high-fiber foods such as fruits and vegetables, low processed foods, high-quality proteins, and healthy fats.

Conclusion

There is no specific diet therapy for the treatment of FM. However, overall, studies indicated that weight control, modified high-antioxidant diets, and nutritional supplementation are beneficial in alleviating symptoms in patients with FM.