bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of carbon location in p-type GaN: Synchrotron x-ray absorption spectroscopy and theory
Authors: Huang Huayang , Yan Xiaolan , Yang Xuelin , Yan Wensheng , Qi Zeming , Wu Shan , Shen Zhaohua , Tang Ning , Xu Fujun , Wang Xinqiang , Ge Weikun , Huang Bing , Shen Bo
Published: December 2022

Identifying atomic configurations of impurities in semiconductors is of fundamental interest and practical importance in designing electronic and optoelectronic devices. C impurity acting as one of the most common impurities in GaN, it is believed for a long time that it substitutes at Ga site forming CGa with +1 charge-state in p-type GaN, while it substitutes at N site forming CN with -1 charge-state in n-type GaN. However, by combining x-ray absorption spectroscopy and first-principles simulations, we observed that C is mainly occupying the N site rather than the Ga one in p-GaN. We further reveal that this is due to an H-induced EF-tuning effect. During growth, the existing H can passivate Mg dopants and upshifts the EF to the upper region of bandgap, leading to the CN formation. After the p-type activation by annealing out H, although the EF is pushed back close to the valence band maximum, whereas the extremely large kinetic barrier can prevent the migration of C from the metastable CN site to ground-state CGa site, hence stabilizing the CN configuration. Additionally, the CN with neutral charge-state (CN0) in the p-GaN is further observed. Therefore, the real C-related hole-killer in p-type GaN could be CN rather than the commonly expected CGa. Our work not only offers the unambiguous evidence for the C defect formation in p-GaN but also contributes significantly to an in-depth understanding of the C-related hole-killers and their critical role on electrical and optoelectrical properties of p-GaN and even p-AlGaN.
Spatial observation of highly directional radiation from a compact 3D photonic-crystal antenna in Ku band
Authors: Dong Guoyan , Guo Xiaofan , Yang Qingshan
Published: December 2022

A three-dimensional compact prototype of a photonic crystal directive antenna is constructed for beam steering and directional radiation in the microwave. Experiments demonstrate that the array of dielectric cylinders placed in a U-shape open metal cavity can be profitably exploited to act as a high-efficiency splitting directive antenna in particular modes. Highly directional radiation has been observed at the fundamental electromagnetic resonance of band edge crystal with a maximum gain of 20.73 dBi and an aperture efficiency of 49.77%. The side-lobes on the E-plane (yoz) are almost constrained in −20 dB benefitting from the band edge lattice-induced resonance on the H-plane (xoy), suppressing the effect of aperture diffraction, and retaining high directivity performance in space. The detected half-power beam widths on the E-plane and H-plane are 7.7° and 8.9°, respectively, agreeing well with the simulations. Different from traditional orientation approaches, the photonic crystal antenna delivers performance of high directivity gain with compact structure, facile preparation, low cost, and high efficiency, which make it suitable for spatial information transmission and modulation and offer potential applications in remote sensing and wireless communication.
Analytical solution and flow topology in a lid-driven S-shaped cavity
Authors: Bilgil Halis , Şafak İbrahim , Öztürk Zafer
Published: December 2022

In this study, the Stokes flow problem in an S-shaped double lid-driven cavity filled with fluid was analyzed. Side edges of the cavity were considered as immovable walls. The flow region was divided into two sub-regions, and the streamfunction in each sub-region was considered as an extension of Papkovich–Faddle eigenfunctions. Parameters in the analytical solution were obtained using biorthogonality conditions. The Newton iteration method was used to obtain the eigenvalues of the problem, and integrals were calculated with the Gaussian quadrature method. It was ensured that solutions made separately for the two sub-regions converge on the interface, which is the intersection of these sub-regions. The two parameters controlling the flow structure were determined as the speed ratio of movable lids (S) and the aspect ratio of the cavity (A). The effects of these parameters on flow structures were shown. New eddy formation mechanisms and bifurcations were observed in the cavity by keeping the speed ratio of the lids constant and slowly changing the aspect ratio.
Nuclear magnetic resonance study on the influence of liquid nitrogen cold soaking on the pore structure of different coals
Authors: Liu Shumin , Sun Haitao , Zhang Dongming , Yang Kun , Wang Dengke , Li Xuelong , Long Kun , Li Yaning
Published: December 2022

As an innovative technology for the stimulation of coalbed methane, liquid nitrogen cold soaking can produce more fractures in coal body and effectively increase the permeability of coal seam. The pore structure distribution of coal affects the permeability of coal and determines the flow and occurrence state of coalbed methane and other fluids in coal. This paper carries out a number of nuclear magnetic resonance tests on coal samples with different coal qualities treated by liquid nitrogen cold soaking and studies the influence law of liquid nitrogen soaking on coal pore structures. It is found that the liquid nitrogen makes the T2 spectral peak shifts to the right, and the anthracite changes from interval T2 spectrum to type T2. It indicates that liquid nitrogen cold soaking in the transformation of pore size to large size improves the pore connectivity and leads to more pore structures. With an increase in times of liquid nitrogen cold soaking, the size and number of coal pore structures gradually increase, and the increasing size is on the order of anthracite > bituminous > lignite. There is a positive correlation between the peak area and the times of liquid nitrogen cold soaking. The porosity and permeability of each coal sample increase with the times of liquid nitrogen cold soaking. From the MRI images of coal samples, it can be found that the liquid nitrogen cold soaking makes the microcracks extend and forms a crack network with other cracks, thereby causing macroscopic damage. The research results are helpful to further reveal the microscopic mechanism of liquid nitrogen cold soaking on coal damage.
Overlooked role associated with the active-site density in perovskite nickelates to the anisotropic catalytic activities for water splitting
Authors: Li Haifan , Wang Yuzhao , Zhang Hao , Fang Xuhui , Zhou Xuanchi , Nie Kaiqi , Xu Xiaoguang , Jiang Yong , Chen Nuofu , Chen Jikun
Published: December 2022

The d-band correlated rare-earth nickelate (ReNiO3) is a typical quantum material that exhibits comparable reactivities to the noble metal oxide in oxygen evolution reactions (OER) for water splitting, apart from their well-known correlated electronic functionalities, such as metal to insulator transition. Nevertheless, the potential anisotropy in the catalyst reactivity of OER for ReNiO3 and its underneath mechanisms are yet under debate. Herein, we demonstrate the previously overlooked role associated with the surface atomic density of the Ni active-site that dominant in the anisotropic OER catalytic activities of ReNiO3. Despite its more localized electron configurations as indicated by the near edge x-ray absorption fine structure analysis and correlated transport, the OER catalytic activity was surprisingly observed to be higher for quasi-single crystalline NdNiO3 (001)/LaAlO3 (110), compared to that of NdNiO3(010)/LaAlO3 (001) and NdNiO3(1¯10)/LaAlO3 (111). This is attributed to the highest surface atomic density associated with the Ni active-site within NdNiO3 (001), compared to NdNiO3 (010) and NdNiO3 (1¯10), and this kinetically reduces the overpotential of OER and the charge transfer resistance of NdNiO3 (001). The anisotropic OER activity sheds a light on the crystal orientation in the optimization of the ReNiO3 catalyst for water splitting.
The M-CHooSe pilot: the acceptability and utilisation of the nurse-led, general practice clinic co-located ‘Mater CALD Healthcare Coordinator Service’ for patients from multicultural backgrounds
Authors: Chua David , Sackey Donata , Jones Meryl , Smith Michelle , Ball Lauren , Johnson Tracey
Published: December 2022

Background Patients from culturally and linguistically diverse (CALD) backgrounds often have unmet healthcare coordination needs. We aimed to evaluate the acceptability, utilisation and perceived benefits of the Mater CALD Health Coordinator Service (M-CHooSe), a pilot, nurse-led, general practice co-located, healthcare coordination service for patients from CALD backgrounds. Methods M-CHooSe began in March 2020 at five Brisbane (Queensland) sites. Process and service user data were collected over 12 months at one site. A survey evaluated primary healthcare professionals’ perceived benefits of the service. Another survey of M-CHooSe nurses examined indicators of service complexity. Results In total, 206 individuals accessed M-CHooSe over the 12-month period. Commonly delivered services included health service advocacy, chart reviews and health system navigation, including addressing social determinants. M-CHooSe nurses reported frequently performing tasks such as following up with external health services and performing health and social care system coordination. M-CHooSe benefits reported by primary healthcare professionals included better patient access to external health services and improved patient understanding of their conditions and treatments. Conclusion Patients were accepting of referrals to M-CHooSE. Primary healthcare professionals also reported a variety of benefits to themselves and their patients because of M-CHooSe. M-ChooSe highlights the potential of a healthcare coordination service for multicultural patients to improve healthcare equity, accessibility, and system efficiency. This project demonstrates the potential value of coordination services to increase patient access and uptake of existing health and social care services for modern Australian communities, thus improving the efficiency and effectiveness of our health system. Further investigations, including user experience, opinions and cost analyses, will be required to confirm the promising benefits of embedding M-CHooSe into usual care.
A novel stem-applied herbicide-capsule methodology for control of the invasive cactus Cereus uruguayanus
Authors: Bradburn Leisa , Campbell Shane , Mellor Vincent , Galea Victor
Published: December 2022

Cereus uruguayanus R.Kiesling is a naturalised, non-opuntioid cactus that has formed large and dense infestations at several locations in the northern Australian rangelands. Of the Cactoideae subfamily, it typically grows into a large, spiny, single- or multi-stemmed candelabra-shaped cactus. While not classified as a Weed of National Significance (WONS) in Australia, it is causing increasing concern, with some local governments declaring it under their local laws. Recent research has identified several herbicides that control C. uruguayanus by using a range of techniques, including basal-bark, cut-stump, foliar, and stem injection applications. Of these, stem injection is one of the recommended options where weeds grow among desirable vegetation because the risk of non-target damage is minimised. This study evaluated C. uruguayanus control using a range of encapsulated dry-formulation herbicides from BioHerbicides Australia (BHA Pty Ltd), using their novel stem-implantation system (Injecta®). In May 2018, an experiment was established in central Queensland to compare the efficacy of six encapsulated herbicides (aminopyralid + metsulfuron-methyl, clopyralid, glyphosate, hexazinone, metsulfuron-methyl, triclopyr + picloram) against an untreated control. Glyphosate was the fastest-acting herbicide, followed by aminopyralid + metsulfuron-methyl and metsulfuron-methyl, with triclopyr + picloram much slower to act. Nevertheless, all four herbicides eventually caused high mortality (≥85%). In contrast, clopyralid and hexazinone were ineffective at the applied rates. Future research is recommended to compare the cost effectiveness of this system against other techniques, particularly those used for stem-injection applications.
Infectious and clinical tuberculosis trajectories: Bayesian modeling with case finding implications
Authors: Ryckman Theresa S. , Dowdy David W. , Kendall Emily A.
Published: December 2022

The importance of finding people with undiagnosed tuberculosis (TB) hinges on their future disease trajectories. Assays for systematic screening should be optimized to find those whose TB will contribute most to future transmission or morbidity. In this study, we constructed a mathematical model that tracks the future trajectories of individuals with TB at a cross-sectional timepoint (“baseline”), classifying them by bacterial burden (smear positive/negative) and symptom status (symptomatic/subclinical). We used Bayesian methods to calibrate this model to targets derived from historical survival data and notification, mortality, and prevalence data from five countries. We combined resulting disease trajectories with evidence on infectiousness to estimate each baseline TB state’s contribution to future transmission. For a person with smear-negative subclinical TB at baseline, the expected future duration of disease was short (mean 4.8 [95% uncertainty interval 3.3 to 8.4] mo); nearly all disease courses ended in spontaneous resolution, not treatment. In contrast, people with baseline smear-positive subclinical TB had longer undiagnosed disease durations (15.9 [11.1 to 23.5] mo); nearly all eventually developed symptoms and ended in treatment or death. Despite accounting for only 11 to 19% of prevalent disease, smear-positive subclinical TB accounted for 35 to 51% of future transmission—a greater contribution than symptomatic or smear-negative TB. Subclinical TB with a high bacterial burden accounts for a disproportionate share of future transmission. Priority should be given to developing inexpensive, easy-to-use assays for screening both symptomatic and asymptomatic individuals at scale—akin to rapid antigen tests for other diseases—even if these assays lack the sensitivity to detect paucibacillary disease.
Topological transformability and reprogrammability of multistable mechanical metamaterials
Authors: Xiu Haning , Liu Harry , Poli Andrea , Wan Guangchao , Sun Kai , Arruda Ellen M. , Mao Xiaoming , Chen Zi
Published: December 2022

Concepts from quantum topological states of matter have been extensively utilized in the past decade to create mechanical metamaterials with topologically protected features, such as one-way edge states and topologically polarized elasticity. Maxwell lattices represent a class of topological mechanical metamaterials that exhibit distinct robust mechanical properties at edges/interfaces when they are topologically polarized. Realizing topological phase transitions in these materials would enable on-and-off switching of these edge states, opening opportunities to program mechanical response and wave propagation. However, such transitions are extremely challenging to experimentally control in Maxwell topological metamaterials due to mechanical and geometric constraints. Here we create a Maxwell lattice with bistable units to implement synchronized transitions between topological states and demonstrate dramatically different stiffnesses as the lattice transforms between topological phases both theoretically and experimentally. By combining multistability with topological phase transitions, this metamaterial not only exhibits topologically protected mechanical properties that swiftly and reversibly change, but also offers a rich design space for innovating mechanical computing architectures and reprogrammable neuromorphic metamaterials. Moreover, we design and fabricate a topological Maxwell lattice using multimaterial 3D printing and demonstrate the potential for miniaturization via additive manufacturing. These design principles are applicable to transformable topological metamaterials for a variety of tasks such as switchable energy absorption, impact mitigation, wave tailoring, neuromorphic metamaterials, and controlled morphing systems.
How English-Medium Instruction affects language and learning outcomes of children in the Maldives
Authors: Bosch Jasmijn E. , Tsimpli Ianthi M. , Guasti Maria Teresa
Published: December 2022

Whilst the vast majority of the Maldivian population speak Dhivehi at home, English typically serves as the only
medium of instruction (MoI) starting from primary school. Teachers have expressed their concerns regarding educational quality, as
many children are taught in a language they do not master sufficiently. The present study aimed to investigate the level of second
language (L2) proficiency in relation to reading abilities and mathematical skills in 25 ten- to twelve-year-old children living
in the Maldives. The results showed relatively low performance on all tasks, despite normal nonverbal intelligence. Moreover, we
found a significant relation between English vocabulary knowledge and reading accuracy. Our findings contribute to a growing body
of research suggesting that using an L2 as the only MoI may be detrimental to literacy development and learning outcomes.
Considering the objectives of educational quality, language maintenance of Dhivehi and the pragmatic value assigned to English, we
argue in favour of a bilingual model of education, in which the importance of native language development is emphasized.
ILEE: Algorithms and toolbox for unguided and accurate quantitative analysis of cytoskeletal images
Authors: Li Pai , Zhang Ze , Tong Yiying , Foda Bardees M. , Day Brad
Published: December 2022

The eukaryotic cytoskeleton plays essential roles in cell signaling and trafficking, broadly associated with immunity and diseases in humans and plants. To date, most studies describing cytoskeleton dynamics and function rely on qualitative/quantitative analyses of cytoskeletal images. While state-of-the-art, these approaches face general challenges: the diversity among filaments causes considerable inaccuracy, and the widely adopted image projection leads to bias and information loss. To solve these issues, we developed the Implicit Laplacian of Enhanced Edge (ILEE), an unguided, high-performance approach for 2D/3D-based quantification of cytoskeletal status and organization. Using ILEE, we constructed a Python library to enable automated cytoskeletal image analysis, providing biologically interpretable indices measuring the density, bundling, segmentation, branching, and directionality of the cytoskeleton. Our data demonstrated that ILEE resolves the defects of traditional approaches, enables the detection of novel cytoskeletal features, and yields data with superior accuracy, stability, and robustness. The ILEE toolbox is available for public use through PyPI and Google Colab.
Innate immune signaling drives late cardiac toxicity following DNA-damaging cancer therapies
Authors: Shamseddine Achraf , Patel Suchit H. , Chavez Valery , Moore Zachary R. , Adnan Mutayyaba , Di Bona Melody , Li Jun , Dang Chau T. , Ramanathan Lakshmi V. , Oeffinger Kevin C. , Liu Jennifer E. , Steingart Richard M. , Piersigilli Alessandra , Socci Nicholas D. , Chan Angel T. , Yu Anthony F. , Bakhoum Samuel F. , Schmitt Adam M.
Published: December 2022

Late cardiac toxicity is a potentially lethal complication of cancer therapy, yet the pathogenic mechanism remains largely unknown, and few treatment options exist. Here we report DNA-damaging agents such as radiation and anthracycline chemotherapies inducing delayed cardiac inflammation following therapy due to activation of cGAS- and STING-dependent type I interferon signaling. Genetic ablation of cGAS–STING signaling in mice inhibits DNA damage–induced cardiac inflammation, rescues late cardiac functional decline, and prevents death from cardiac events. Treatment with a STING antagonist suppresses cardiac interferon signaling following DNA-damaging therapies and effectively mitigates cardiac toxicity. These results identify a therapeutically targetable, pathogenic mechanism for one of the most vexing treatment-related toxicities in cancer survivors.
Noether charge formalism for Weyl transverse gravity
Authors: Alonso-Serrano Ana , Garay Luis J , Liška Marek
Published: December 2022

Weyl transverse gravity (WTG) is a gravitational theory that is invariant under transverse diffeomorphisms and Weyl transformations. It is characterised by having the same classical solutions as general relativity while solving some of its issues with the cosmological constant. In this work, we first find the Noether currents and charges corresponding to local symmetries of WTG as well as a prescription for the symplectic form. We then employ these results to derive the first law of black hole mechanics in WTG (both in vacuum and in the presence of a perfect fluid), identifying the total energy, the total angular momentum, and the Wald entropy of black holes. We further obtain the first law and Smarr formula for Schwarzschild-anti-de Sitter and pure de Sitter spacetimes, discussing the contributions of the varying cosmological constant, which naturally appear in WTG. Lastly, we derive the first law of causal diamonds in vacuum.
Building post-Newtonian neutron stars
Authors: Andersson Nils , Gittins Fabian , Yin Shanshan , Panosso Macedo Rodrigo
Published: December 2022

Owed to their compactness, neutron stars involve strong gravity and extreme density physics. Nevertheless, at present, there are a variety of problems where progress (at least conceptually) can be made in the context of weak gravity. Motivated by this we examine how accurately one can model neutron stars using the post-Newtonian (pN) approximation to general relativity. In general, we find there is a significant degree of freedom in how the pN equations of stellar structure can be formulated. We discuss this flexibility in the formulation and provide examples to demonstrate the impact on stellar models. We also consider the (closely related) problem of building neutron stars using isotropic coordinates. In this context, we provide a new strategy for solving the equations (based on a scaling argument) which significantly simplifies the problem.
Current loop and point dipole configurations for magnetic multipoles
Authors: Majic Matt
Published: December 2022

Multipoles are a widely used tool in magnetostatics, but very little is known about the possible current distributions that may generate them. Here we propose constructions for the currents corresponding to the multipole fields. We begin with a small current loop which creates a dipolar field, and then investigate how to construct current configurations for multipoles of all degrees and orders, by using differentiation and considering ideas of symmetry and nesting loops. We also investigate using point dipoles instead of loops. Many equivalent configurations are found, most of which are not presented elsewhere in the literature.
Weighted envelope spectrum based on reselection mechanism and its application in bearing fault diagnosis
Authors: Zhang Yongxiang , Huang Baoyu
Published: December 2022

As a powerful algorithm, fast spectral correlation (Fast-SC) is widely used in bearing fault diagnosis. However, the interference of strong background noise and the existence of multiple fault-related frequency bands make it difficult to diagnose bearing faults using enhanced envelope spectrum and improved envelope spectrum on the basis of Fast-SC. To alleviate the problem, fast kurtogram is imitated to divide the spectral frequency bands; then, the threshold-based diagnostic feature (TDF) of each integration band is calculated to guide the weighting function of the corresponding level; finally, weighted envelope spectrum with the largest TDF is determined as the output; this process is called the reselection mechanism. Simulation and experimental results indicate that the design of weighting function highlights the contribution of the fault-related frequency bands, and the reselection mechanism further improves its performance.
Identification of wind turbine gearbox weak compound fault based on optimal empirical wavelet transform
Authors: Hu Mantang , Wang Guofeng , Ma Kaile
Published: December 2022

A double modulation phenomenon is found in wind turbine gearbox compound fault signals, consisting of a resonance modulation frequency band and an asymmetric modulation frequency band. The modal aliasing and the double modulation phenomena make it difficult to use empirical wavelet transform to obtain the spectral components in the meshing modulation regions. Our main contribution is to establish an optimal empirical wavelet transform (OEWT) framework for weak feature extraction of compound faults, which incorporates the optimal velocity synchronous linear chirplet transform (OVSLCT) and the simulated annealing (SA) algorithm to obtain the optimal parameters of the filter bank. The frequency boundary of the fault component is obtained through OVSLCT rather than the extreme value of the spectrum. A filter transition band width optimization scheme is proposed in which the optimal transition band width of the filter bank in EWT is optimized by the SA algorithm. Compared with the original EWT and variational mode decomposition, OEWT can better obtain the compound fault characteristic frequency and solve the mode aliasing problem.
DeSeg: auto detector-based segmentation for brain metastases
Authors: Yu Hui , Zhang Zhongzhou , Xia Wenjun , Liu Yan , Liu Lunxin , Luo Wuman , Zhou Jiliu , Zhang Yi
Published: December 2022

Delineation of brain metastases (BMs) is a paramount step in stereotactic radiosurgery treatment. Clinical practice has specific expectation on BM auto-delineation that the method is supposed to avoid missing of small lesions and yield accurate contours for large lesions. In this study, we propose a novel coarse-to-fine framework, named detector-based segmentation (DeSeg), to incorporate object-level detection into pixel-wise segmentation so as to meet the clinical demand. DeSeg consists of three components: a center-point-guided single-shot detector to localize the potential lesion regions, a multi-head U-Net segmentation model to refine contours, and a data cascade unit to connect both tasks smoothly. Performance on tiny lesions is measured by the object-based sensitivity and positive predictive value (PPV), while that on large lesions is quantified by dice similarity coefficient (DSC), average symmetric surface distance (ASSD) and 95% Hausdorff distance (HD95). Besides, computational complexity is also considered to study the potential of method in real-time processing. This study retrospectively collected 240 BM patients with Gadolinium injected contrast-enhanced T1-weighted magnetic resonance imaging (T1c-MRI), which were randomly split into training, validating and testing datasets (192, 24 and 24 scans, respectively). The lesions in the testing dataset were further divided into two groups based on the volume size (small S: ≤1.5 cc, N = 88; large L: > 1.5 cc, N = 15). On average, DeSeg yielded a sensitivity of 0.91 and a PPV of 0.77 on S group, and a DSC of 0.86, an ASSD 0f 0.76 mm and a HD95 of 2.31 mm on L group. The results indicated that DeSeg achieved leading sensitivity and PPV for tiny lesions as well as segmentation metrics for large ones. After our clinical validation, DeSeg showed competitive segmentation performance while kept faster processing speed comparing with existing 3D models.
The effect of intermediate layer densification on the critical current of a Bi-2223 superconducting joint
Authors: Takeda Y , Nishijima G , Inoue K , Takano Y , Kitaguchi H
Published: December 2022

The effect of intermediate layer densification on the critical current (I
c) of Bi-2223 superconducting joints was quantitatively studied. First, we evaluated the phase purity, density, and intergrain critical current density (J
c) of Bi-2223 thick film samples simulating the intermediate layer. The samples were uniaxially pressed to increase the film density. After two heat treatments of the pressed film, an increase in J
c was achieved. Second, we fabricated superconducting joints by synthesizing an intermediate layer between two Bi-2223 tapes. Applying a uniform uniaxial pressure on the joint resulted in the formation of a homogeneous structure. This process enables the reproducible fabrication of superconducting joints with high n values. The I
c of the superconducting joint was increased by intermediate pressing (IP) and two heat treatments. However, pressing at high pressures can mechanically damage filaments in the Bi-2223 tapes, leading to a decrease in I
c. Sample characterization showed that the optimum IP pressure range to produce high I
c was 1.5–2 × 108 Pa. We confirmed that pressing densified the intermediate layer of the superconducting joints. Our experimental results and analyses reveal that densification of the intermediate layer increases the I
c of Bi-2223 superconducting joints.
Efficient positron trapping and extraction with a center-hole SiC remoderator
Authors: Michishio Koji , Higaki Hiroyuki , Ishida Akira , Oshima Nagayasu
Published: December 2022

Trapping technologies of positrons, the antimatter counterpart of electrons, are indispensable for various atomic, molecular, and optical experiments and for material analyses that use positron swarms. Efficient trapping of high-intensity positron beams generated by electron linear accelerators (LINACs) will improve the quality and throughput rate of experiments but have yet to be practically realized. In the present work, we demonstrate the efficient trapping and extraction of a LINAC-based positron beam by using a silicon carbide (SiC) remoderator with a center hole. The positron beam was remoderated by 4H-SiC wafers in the back-reflection geometry followed by accumulation in an electromagnetic trap with CF4 cooling gas. A rotating electric field was driven to spatially compress the accumulated positrons, enabling the lossless extraction of the positrons through the SiC hole. A trapping efficiency in the higher 20% range was achieved. The proposed trapping scheme employing a center-hole SiC remoderator is thus a practical technique to accumulate and cool positron beams generated by LINACs.
Enhancing quantum coherence of a fluxonium qubit by employing flux modulation with tunable-complex-amplitude
Authors: Cheng Jia-Ming , Zhang Yong-Chang , Zhou Xiang-Fa , Zhou Zheng-Wei
Published: December 2022

We propose to protect fluxonium qubits that are away from half flux quantum against environmental noises, especially

1

/

f

flux noise, by adopting a modulated flux with tunable-complex-amplitude. Using open-system Floquet theory, we derive a Lindblad equation and extract decoherent rates for pure-dephasing, excitation and relaxation. After examining intrinsic attributes of the flux driven fluxonium qubit, we put forward an analytic manner to locate dynamical sweet spots for fast and weak driving. Continuous families of dynamical sweet spots are found in the parameter plane of relative amplitude factor and relative phase. Around a family of dynamical sweet spots or between two families of dynamical sweet spots, there exist continuous regions with long coherent times that exceed

100
 
μ

s

. Taking advantage of the two noise-insensitive channels: relative amplitude factor and relative phase, a flux driven fluxonium qubit can become immune to flux noises from both the dc and ac flux amplitudes. And the optimal driving amplitudes are no longer isolated at a certain driving frequency, but become continuous. This is in sharp contrast to the usual schemes based on flux modulation with real-amplitude. As a result, there are plenty of manipulating flexibility in our flux driving scheme with tunable-complex-amplitude, which may be useful in logical operations among flux driven fluxonium qubits or other flux qubits.
Controlled quantum teleportation between discrete and continuous physical systems
Authors: El Kirdi M , Slaoui A , Ikken N , Daoud M , Ahl Laamara R
Published: December 2022

Quantum teleportation of an unknown state basing on the interaction between discrete-valued states (DV) and continuous-valued states (CV) presented a particular challenge in quantum technologies. Here we consider the problem of controlled quantum teleportation of an amplitude-matched CV qubit, encoded by a coherent state of a varied phase as a superposition of the vacuum- and single-photon optical states among two distant partners Alice and Bob, with the consent of controller, Charlie. To achieve this task, we use an hybrid tripartite entangled state (interaction between the discrete and continuous variables states) as the quantum resource where the coherent part belongs to Alice, while the single-photon belongs to Bob and Charlie and the CV qubit is at the disposal of Alice. The discrete-continuous interaction is realized on highly transmissive beam-splitter. We have shown that the perfectly of teleportation fidelity depends on the phase difference between the phase of the state to teleport and the phase of the sender’s mode, we found that for a difference which approaches 0 or π, near perfect controlled quantum teleportation can be obtained in terms of the fidelity and independently of the amplitude α and the squeezing parameter ζ. Experimentally, this proposed scheme has been implemented using linear optical components such as beam splitter, phase shifters and photon counters.
Neural network reconstruction of H'(z) and its application in teleparallel gravity
Authors: Mukherjee Purba , Said Jackson Levi , Mifsud Jurgen
Published: December 2022

In this work, we explore the possibility of using artificial neural networks to impose constraints on teleparallel gravity and its f(T) extensions. We use the available Hubble parameter observations from cosmic chronometers and baryon acoustic oscillations from different galaxy surveys. We discuss the procedure for training a network model to reconstruct the Hubble diagram. Further, we describe the procedure to obtain H'(z), the first order derivative of H(z), using artificial neural networks which is a novel approach to this method of reconstruction. These analyses are complemented with further studies on the impact of two priors which we put on H
0 to assess their impact on the analysis, which are the local measurements by the SH0ES team (H
0
R20 = 73.2 ± 1.3 km Mpc-1 s-1) and the updated TRGB calibration from the Carnegie Supernova Project (H
0
TRGB = 69.8 ± 1.9 km Mpc-1 s-1), respectively. Additionally, we investigate the validity of the concordance model, through some cosmological null tests with these reconstructed data sets. Finally, we reconstruct the allowed f(T) functions for different combinations of the observational Hubble data sets. Results show that the ΛCDM model lies comfortably included at the 1σ confidence level for all the examined cases.
A Candid Assessment of Standard Cosmology
Authors: Melia Fulvio
Published: December 2022

Modern cosmology is broadly based on the Cosmological principle, which assumes homogeneity and isotropy as its foundational pillars. Thus, there is not much debate about the metric (i.e., Friedmann-Lemaître-Robertson-Walker; FLRW) one should use to describe the cosmic spacetime. But Einstein’s equations do not unilaterally constrain the constituents in the cosmic fluid, which directly determine the expansion factor appearing in the metric coefficients. As its name suggests, ΛCDM posits that the energy density is dominated by a blend of dark energy (typically a cosmological constant, Λ), cold dark matter (and a “contamination” of baryonic matter) and radiation. Many would assert that we have now reached the age of “precision” cosmology, in which measurements are made merely to refine the excessively large number of free parameters characterizing its empirical underpinnings. But this mantra glosses over a growing body of embarrassingly significant failings, not just “tension” as is sometimes described, as if to somehow imply that a resolution will eventually be found. In this paper, we take a candid look at some of the most glaring conflicts between the standard model, the observations, and several foundational principles in quantum mechanics, general relativity and particle physics. One cannot avoid the conclusion that the standard model needs a complete overhaul in order to survive.
Global SOLPS-ITER and ERO2.0 coupling in a linear device for the study of plasma–wall interaction in helium plasma
Authors: Alberti G. , Tonello E. , Carminati P. , Uccello A. , Bonnin X. , Romazanov J. , Brezinsek S. , Passoni M.
Published: December 2022

Plasma–wall interaction (PWI) is a great challenge in the development of a nuclear fusion power plant. To investigate phenomena like erosion of plasma-facing components, impurity transport and redeposition, one needs reliable numerical tools for the description of both the plasma and the material evolution. The development of such tools is essential to guide the design and interpretation of experiments in present and future fusion devices. This contribution presents the first global simulation of PWI processes in a linear plasma device mimicking the boundary plasma conditions in toroidal ones, including both the description of plasma and impurity transport and of plasma-facing material evolution. This integrated description is obtained by coupling two of the state-of-the-art numerical codes employed to model the plasma boundary and the PWI, namely SOLPS-ITER and ERO2.0. Investigation of helium plasma is also of primary importance due to the role helium will have during ITER pre-fusion power operation, when it is planned to be used as one of the main plasma species, as well as fusion ash in full power operation. The plasma background is simulated by SOLPS-ITER and the set of atomic reactions for helium plasmas is updated, including charge-exchange and radiative heat losses. ERO2.0 is used to assess the surface erosion in the GyM vessel, using different wall materials (e.g. carbon, iron or tungsten) and applying different biasing voltage. Eroded particles are followed within the plasma to assess their redeposition location. The ionization probability of the different materials in the GyM plasma is inferred through the energy distribution of impacting particles and its effects on migration are investigated.
Effect of edge ion temperature on the divertor tungsten sputtering in WEST
Authors: Li Y. , Fedorczak N. , Xu G.S. , Liang Y. , Brezinsek S. , Morales J.
Published: December 2022

The influence of upstream ion temperature in the scrape-off layer (SOL) on the tungsten (W) sputtering in the divertor is studied in the WEST tokamak. For an almost constant power into the SOL, the upstream ion temperature and its ratio over the electron temperature gradually increase with the decrease of electron density in the SOL. This increment is observed to enhance the energy transfer from ions to electrons. This increases the downstream electron temperature and by coupling of electrons and ions, the impact energy of ions causing W sputtering in the divertor. This enhancement mechanism may become crucial to sputtering the W material for high upstream T
i/T
e ratio since the impact energy of ions in the divertor would increase accordingly.
Recent Progress in Quantum Key Distribution Network Deployments and Standards
Authors: Stanley M , Gui Y , Unnikrishnan D , Hall S.R.G , Fatadin I
Published: December 2022

Quantum key distribution (QKD) provides in principle unconditional security of key sharing based on the laws of physics only. In the last decade, several experimental and commercial QKD networks have been built and operated worldwide. Demonstrational applications of QKD in financial institutions, government networks, and critical infrastructures such as the power grid have been initially explored. However, large-scale deployment and full-scale commercialization of QKD networks still faces some technological and standardisation challenges. In this paper, recent developments and in-field deployments of QKD networks are reviewed and advancements in QKD standardisation are also discussed.
A novel ANN adaptive Riemannian-based kernel classification for motor imagery
Authors: Yacine Fodil , Salah Haddab , Amar Kachenoura , Ahmad Karfoul
Published: December 2022

More recently, a number of studies show the interest of the use of the Riemannian geometry in EEG classification. The idea is to exploit the EEG covariance matrices, instead of the raw EEG data, and use the Riemannian geometry to directly classify these matrices. This paper presents a novel Artificial Neural Network approach based on an Adaptive Riemannian Kernel, named ARK-ANN, to classify Electroencephalographic (EEG) motor imaging signals in the context of Brain Computer Interface (BCI). A multilayer perceptron is used to classify the covariance matrices of Motor Imagery (MI) signals employing an adaptive optimization of the testing set. The contribution of a geodesic filter is also assessed for the ANN and the original method which uses an SVM classifier. The results demonstrate that the ARK-ANN performs better than the other methods and the geodesic filter gives slightly better results in the ARK-SVM, considered here as the reference method, in the case of inter-subject classification (accuracy of 87.4% and 86% for ARK-ANN and ARK-SVM, respectively). Regarding the cross-subject classification, the proposed method gives an accuracy of 77.3% and increases the precision by 8.2% in comparison to the SVM based method.
Inferring directional interactions in collective dynamics: a critique to intrinsic mutual information
Authors: De Lellis Pietro , Ruiz Marín Manuel , Porfiri Maurizio
Published: December 2022

Pairwise interactions are critical to collective dynamics of natural and technological systems. Information theory is the gold standard to study these interactions, but recent work has identified pitfalls in the way information flow is appraised through classical metrics—time-delayed mutual information and transfer entropy. These pitfalls have prompted the introduction of intrinsic mutual information to precisely measure information flow. However, little is known regarding the potential use of intrinsic mutual information in the inference of directional influences to diagnose interactions from time-series of individual units. We explore this possibility within a minimalistic, mathematically tractable leader–follower model, for which we document an excess of false inferences of intrinsic mutual information compared to transfer entropy. This unexpected finding is linked to a fundamental limitation of intrinsic mutual information, which suffers from the same sins of time-delayed mutual information: a thin tail of the null distribution that favors the rejection of the null-hypothesis of independence.
Directed random geometric graphs: structural and spectral properties
Authors: Peralta-Martinez Kevin , Méndez-Bermúdez J A
Published: December 2022

In this work we analyze structural and spectral properties of a model of directed random geometric graphs: given n vertices uniformly and independently distributed on the unit square, a directed edge is set between two vertices if their distance is smaller than the connection radius

ℓ

, which is randomly drawn from a Pareto distribution. This Pareto distribution is characterized by the power-law decay α and the lower bound of its support

ℓ
0

; thus the graphs depend on three parameters

G
(
n
,
α
,

ℓ
0

)

. By increasing

ℓ
0

, for fixed

(
n
,
α
)

, the model transits from isolated vertices (

ℓ
0

≈
0

) to complete graphs (

ℓ
0

=

2

). We first propose a phenomenological expression for the average degree

⟨
k
(
G
)
⟩

which works well for α > 3, when k is a self-averaging quantity. Then we numerically demonstrate that

〈

V
x

(
G
)
〉
≈
n
[
1
−
exp
(
−
〈
k
〉
]

, for all α, where

V
x

(
G
)

is the number of nonisolated vertices of G. Finally, we explore the spectral properties of

G
(
n
,
α
,

ℓ
0

)

by the use of adjacency matrices represented by diluted random matrix ensembles; a non-Hermitian and a Hermitian one. We find that

⟨
k
⟩

is a good scaling parameter of spectral and eigenvector properties of G mainly for large α.
Sarnak’s conjecture for a class of rank-one subshifts
Authors: Etedadialiabadi Mahmood , Gao Su
Published: December 2022

Using techniques developed by Kanigowski, Lemańczyk, and Radziwiłł [Fund. Math. 255 (2021), pp. 309–336], we verify Sarnak’s conjecture for two classes of rank-one subshifts with unbounded cutting parameters. The first class of rank-one subshifts we consider is called almost complete congruency classes (accc), the definition of which is motivated by the main result of Foreman, Gao, Hill, Silva, and Weiss [Isr. J. Math., To appear], which implies that when a rank-one subshift carries a unique nonatomic invariant probability measure, it is accc if it is measure-theoretically isomorphic to an odometer. The second class we consider consists of Katok’s map and its generalizations.
Discrimination and Sleep: Differential Effects by Type and Coping Strategy
Authors: Majeno Angelina , Molina Kristine M , Frisard Christine F , Lemon Stephenie C , Rosal Milagros C
Published: December 2022

Background

Discrimination has been posited as a contributor of sleep disparities for Latinxs. The strategy used to cope with discrimination may reduce or exacerbate its effects on sleep. This study examined whether different types of discrimination (everyday and major lifetime discrimination) were associated with sleep indices (quality, disturbances, efficiency) and whether coping strategy used moderated associations.

Method

Data of Latinx adults (N = 602; 51% women, 65% Dominican, Mage = 46.72 years) come from the Latino Health and Well-being Project, a community-based, cross-sectional study of Latinxs in Lawrence, MA. Multiple linear regressions were estimated separately for each sleep outcome.

Results

Everyday discrimination was significantly associated with poorer sleep quality and greater disturbances; major lifetime discrimination was significantly associated with worse sleep across the three sleep indices. Coping strategy moderated associations between discrimination and sleep. Compared with Latinxs who used passive coping, those who used passive–active coping strategies had poorer sleep quality the more they experienced everyday discrimination. Latinxs who used any active coping strategy, compared with passive coping, had greater sleep disturbances the more frequently they experienced major lifetime discrimination.

Conclusions

Findings show that everyday discrimination and major lifetime discrimination are associated with different dimensions of sleep and suggest that coping with discrimination may require the use of different strategies depending on the type of discrimination experienced.