bluuebunny/crossref_metadata_2025 huggingface dataset:
Continuum kinetic investigation of the impact of bias potentials in the current saturation regime on sheath formation
Authors: Skolar C. R. , Bradshaw K. , Juno J. , Srinivasan B.
Published: January 2023

In this work, we examine sheath formation in the presence of bias potentials in the current saturation regime for pulsed power fusion experiments. It is important to understand how the particle and heat fluxes at the wall may impact the wall material and affect electrode degradation. Simulations are performed using the 1X-1V Boltzmann–Poisson system for a proton–electron plasma in the presence of bias potentials ranging from 0 to 10 kV. The results indicate that the sheath near the anode remains generally the same as that of a classical sheath without the presence of a bias potential. However, the sheath near the cathode becomes more prominent with a larger potential drop, a significant decrease in the electron density, and larger sheath lengths. The spatially constant current density increases to a saturation value with the increasing bias potential. For high bias potentials, the material choice needs to consider that the anode faces significantly larger particle and heat fluxes compared to the cathode. In general, the results trend with theory with differences attributed to the simplified assumptions in the theory and the kinetic effects considered in the simulations. Due to the significant computational cost of a well resolved 1X-2V simulation, only one such simulation is performed for the 5 kV case showing higher current.
Large magnetic-field-induced strains in sintered chromium tellurides
Authors: Kubota Yuki , Okamoto Yoshihiko , Kanematsu Tomoya , Yajima Takeshi , Hirai Daigorou , Takenaka Koshi
Published: January 2023

Sintered samples of Cr3Te4 and Cr2Te3 are found to show large strains accompanied by large volume changes under a magnetic field. In Cr3Te4, volume increases of ΔV/V = 500–1170 ppm by applying a magnetic field of 9 T are observed over the entire temperature range below 350 K. At room temperature, the ΔV/V value exceeds 1000 ppm, which is considerably larger than the maximum values reported for Cr-based magnets, thus far, and is comparable to the room-temperature value of forced-volume magnetostriction in invar alloys. Cr2Te3 shows a large ΔV/V of 680 ppm when applying a magnetic field of 9 T at 200 K. Both samples display particularly large volume increases around the Curie temperature, where they also show negative thermal expansion due to the microstructural effects, suggesting that the cooperation between anisotropic lattice deformation associated with the magnetic ordering and microstructural effects is essential for the manifestation of the large magnetic-field-induced volume changes.
All-optically generating and monitoring interlayer expansion of layered GaSe via in situ second harmonic generation
Authors: Li Yuanyuan , Zhang Lu , Wang Tianjie , Xie Jiaxin , Wang Min , Qi Zeming , Cui Qiannan , Chang Jianhua
Published: January 2023

Interlayer-distance engineering can provide a degree of freedom to tailor the intrinsic physical properties of 2D layered semiconductors and van der Waals heterostructures. In this Letter, we report an all-optical technique to simultaneously generate and monitor interlayer expansions of multilayer GaSe lattice via optical second harmonic generation (SHG). Heat induced by the absorption of fundamental laser can trigger interlayer expansion, while intensity change of SHG caused by mediated superposition of SHG field in expanded layers can monitor the level of interlayer expansion. Our results open an avenue to all-optically engineer interlayer distance of 2D layered semiconductors.
A perspective on the manipulation of orbital angular momentum states in nonlinear optics
Authors: Chen Sixin , Ma Taxue , Yu Qian , Chen Pengcheng , Yang Xinzhe , Wu Xuewei , Sang Hai , Hu Xiaopeng , Zhu Shining , Xiao Min , Zhang Yong
Published: January 2023

Orbital angular momentum (OAM) of light has been widely investigated in optical manipulation, optical communications, optical storage, and precision measurement. In recent years, the studies of OAM are expanded to nonlinear and quantum optics, paving a way to high-quality nonlinear imaging, high-capacity quantum communication, and many other promising applications. In this Perspective, we first summarize the fundamental research on OAM in nonlinear optics. Then, we introduce its recent applications in nonlinear imaging (including nonlinear spiral imaging and OAM-multiplexing nonlinear holography) and high-dimensional quantum entanglement. In particular, we highlight the manipulations of OAM through various functional nonlinear photonic crystals. Finally, we discuss the further developments of OAM-based nonlinear and quantum techniques in the near future.
On the dynamics of buoyant jets in a linearly stratified ambient
Authors: Mirajkar Harish N. , Mukherjee Partho , Balasubramanian Sridhar
Published: January 2023

We report mean flow and turbulence characteristics of a buoyant jet evolving in a linearly stratified ambient with stratification strength N=0.4 s−1. The velocity and density fields are captured experimentally using simultaneous particle image velocimetry and planar laser-induced fluorescence technique. We report our findings by strategically choosing four axial locations such that it covers different flow regimes; namely, momentum-dominated region, buoyancy-dominated region, neutral buoyant layer, and plume cap region. The results at these axial locations are presented as a function of the radial co-ordinate to provide a whole field picture of the flow dynamics. From the mean axial velocity and density fields, it is seen that the velocity and the scalar (density) widths are of the same magnitude in the momentum-dominated region but show significant difference in the buoyancy-dominated region and beyond. It is also seen that the axial velocity for the buoyant jet is consistently higher than pure jet at different axial locations due to buoyancy-aided momentum. With the help of turbulent kinetic energy (TKE) budget analysis, it is seen that the shear production (P) and TKE dissipation (ϵ) for a buoyant jet are higher compared to the case of pure jet at different axial locations, cementing the role of buoyancy and stratification on the flow dynamics. Further, it is observed that the buoyancy flux (B) aids and destroys TKE intermittently in the radial direction, and it is at least O(102) smaller than P, ϵ, and the mean flow buoyancy flux (F). Finally, the relative strength of the turbulent transport of momentum to that of scalar in the radial direction is quantified using the turbulent Prandtl number, Prt. It is seen that Prt ≈1 upto the neutral buoyant layer and ≈ 0.6 in the plume cap region. The current set of results obtained from experiments are first of its kind and elucidates various aspects of the flow which hitherto remained unknown and will also prove to be useful in testing numerical simulations for buoyancy-driven flows.
A gate- and flux-controlled supercurrent diode effect
Authors: Paolucci F. , De Simoni G. , Giazotto F.
Published: January 2023

Non-reciprocal charge transport in supercurrent diodes (SDs) has polarized growing interest in the last few years for their potential applications in superconducting electronics (SCE). So far, SD effects have been reported in complex hybrid superconductor/semiconductor structures or metallic systems subject to moderate magnetic fields, thus showing limited potentiality for practical applications in SCE. Here, we report the design and realization of a monolithic device that shows a valuable SD effect by exploiting a Dayem bridge-based superconducting quantum interference device. Our structure allows reaching rectification efficiencies (η) up to ∼6%. Moreover, the absolute value and the polarity of η can be selected on demand by the modulation of an external magnetic flux or by a gate voltage, thereby guaranteeing high versatility and improved switching speed. Furthermore, our SD operates in a wide range of temperatures up to about 70% of the superconducting critical temperature of the titanium film composing the interferometer. Our SD effect can find extended applications in SCE by operating in synergy with widespread superconducting technologies such as nanocryotrons, rapid single flux quanta, and memories.
Wall temperature effects on the hypersonic boundary-layer transition over an inclined, blunt cone
Authors: Wang Qian , Xiang Xinghao , Dong Siwei , Yuan Xianxu , Chen Jianqiang , Chen Xi
Published: January 2023

Wall temperature is a crucial factor for the transition of hypersonic boundary layers. This paper investigates the wall temperature effects on the hypersonic boundary-layer transition over an inclined blunt cone with two wall temperatures by direct numerical simulations and instability analysis. The breakdown processes of leeward streamwise vortices and crossflow vortices are both studied. Inner modes with lower phase velocities and outer modes with higher phase velocities are responsible for the breakdown of leeward streamwise vortices, respectively, in cooled- and heated-wall cases. A higher wall temperature will promote the boundary layer transition in the vicinity of the leeward centerline due to the collision of nearby crossflow vortices with the leeward mushroom structure, instead of by destabilizing inner and outer modes. In the crossflow-dominated region, the transition is triggered by the interaction between second modes and crossflow vortices for the cooled-wall case. Increasing the wall temperature will promote the transition in this region even though second modes are suppressed.
Recovery of the family status of Pericambalidae Silvestri, 1909, stat. nov. (Diplopoda: Spirostreptida: Cambalidea), with a revision of the genera and species from China
Authors: Jiang Xuan-Kong , Shear William A. , Ye Li-Ping , Chen Hui-Ming , Xie Zhi-Cai
Published: January 2023

The millipede subfamily Pericambalinae Silvestri, 1909 is poorly understood and the taxonomic status remains controversial. Pericambalinae was regarded as either a subfamily of Cambalopsidae or an independent family. To address this issue, we conducted a molecular phylogenetic analysis and a morphological revision, and the genera and species from China are also revised. The results support the recovery of the family status, Pericambalidae, stat. nov. The morphological differences between Bilingulus Zhang & Li, 1981 and Parabilingulus Zhang & Li, 1981 are shown to be caused by post-embryonic development (anamorphosis and non-systemic metamorphosis) and both of these should be junior synonyms of Pericambala Silvestri, 1909 (Pericambala = Bilingulus, syn. nov. = Parabilingulus, syn. nov.). Three new combinations are proposed: Pericambala simplicia (Mauriès & Nguyen Duy-Jacquemin, 1997), comb. nov., Pericambala aramula (Zhang & Li, 1981), comb. nov. and Pericambala sinica (Zhang & Li, 1981), comb. nov. The mature specimens of Pericambala simplicia, comb. nov. and Pericambala aramula, comb. nov. were collected from the type localities and are described for the first time. A new species, Pericambala cordata, sp. nov. is described. After revision, Pericambalidae contains two genera and six species with one genus and four species recorded from China. Due to a deficiency in outgroup sampling, the phylogenetic status of Pericambalidae in the suborder Cambalidea remains uncertain. Variation of the gnathochilarium in Cambalidea is discussed and a key to the species of Pericambala in China is also provided. This research lays a foundation for further revision of Cambalidea in the future. ZooBank: urn:lsid:zoobank.org:pub:BDA46BCE-102B-45FE-A963-47F029A09E76.
Prevalence of five curable sexually transmitted infections and associated risk factors among tertiary student men who have sex with men in Nairobi, Kenya: a respondent-driven sampling survey†
Authors: Mwaniki Samuel Waweru , Kaberia Peter Mwenda , Mugo Peter Mwangi , Palanee-Phillips Thesla
Published: January 2023

Background Young men who have sex with men (MSM) are a key population at high risk of sexually transmitted infections (STIs). We conducted a respondent-driven sampling (RDS) bio-behavioural survey to estimate the prevalence of five curable STIs: chlamydia, gonorrhoea, syphilis, trichomoniasis and Mycoplasma genitalium infection, and associated risk factors among tertiary student MSM (TSMSM) in Nairobi, Kenya. Methods Between February and March 2021, we recruited 248 TSMSM aged ≥18 years who self-reported engaging in anal and/or oral sex with another man in the past year. Samples collected included urine, anorectal and oropharyngeal swabs for pooled Chlamydia trachomatis, Mycoplasma genitalium, Neisseria gonorrhoeae and Trichomonas vaginalis testing using multiplex nucleic acid amplification tests, and venous blood for serological Treponema pallidum screening and confirmation of current infection. Participants self-completed a behavioural survey on a REDCap digital platform. Data analysis was done using RDS-Analyst (v0.72) and Stata (v15). Differences in proportions were examined using the chi-squared (χ2) test, and unweighted multivariate logistic regression was used to assess factors associated with STI prevalence. Results RDS-adjusted prevalence rates of at least one of the five STIs, chlamydia, gonorrhoea, Mycoplasma genitalium infection, trichomoniasis and latent syphilis were 58.8%, 51.0%, 11.3%, 6.0%, 1.5% and 0.7%, respectively. Factors independently associated with STI prevalence were inconsistent condom use (adjusted odds ratio (AOR) = 1.89, 95% confidence interval (CI): 1.03–3.47, P = 0.038) and the last sex partner being a regular partner (AOR = 2.35, 95% CI: 1.12–4.92, P = 0.023). Conclusion STI prevalence among TSMSM in Nairobi, Kenya, is disturbingly high, demonstrating urgent need for tailored testing, treatment and prevention interventions for this population.
The role of drought conditions on the recent increase in wildfire occurrence in the high Andean regions of Peru
Authors: Zubieta Ricardo , Ccanchi Yerson , Martínez Alejandra , Saavedra Miguel , Norabuena Edmundo , Alvarez Sigrid , Ilbay Mercy
Published: January 2023

Wildfire occurrence has increased sharply in the last two decades in the Peruvian Andes. There is, however, little research on wildfires and their impacts. This study explores the conditions conducive to wildfire during 2020. MODIS images were collected to estimate the development of vegetation. In addition, ground-based monthly and satellite-based daily precipitation data were collected. Daily precipitation regularity was evaluated using a concentration index (CI), while monthly precipitation was used to estimate the Standard Precipitation Index (SPI). We used also the Global Vegetation Moisture Index (GVMI), which is a useful indicator of vegetation dynamics based on vegetation moisture. Our results do not indicate a direct link between rainfall regularity (lowest  CI values) and development of vegetation. Although the SPI drought analysis using seasonal rainfall indicated nearly normal conditions during 2019–2020, analysis of dry-day frequency (DDF) suggests that the dry period played an important role between September and November 2020, producing conditions similar to the droughts of 2005, 2010 and 2016. GVMI also showed below-average values from April to November. We corroborate the usefulness of DDF for monitoring the potential increase in wildfire conditions. A controlled burn policy could offer a more useful way to reduce the impacts of wildfire.
Use of the Wildland Fire Decision Support System (WFDSS) for full suppression and managed fires within the Southwestern Region of the US Forest Service
Authors: Fillmore Stephen D. , Paveglio Travis B.
Published: January 2023

Background United States federal wildland fire policy requires the use of formal decision support systems (DSS) for fire incidents that last for an extended time. However, the ways that wildfire managers use DSSs in decisions regarding fire management remain understudied, including how users engage with or utilise them to make strategic decisions. Aims Researchers sought to understand how users engage with the Wildland Fire Decision Support System (WFDSS), their view of its utilities and challenges, and their perspectives about WFDSS training. Methods We present the results of thematic analysis from 46 semi-structured interviews with employees in the US Forest Service Southwestern Region with a WFDSS user account. Key results Users indicated that the program is viewed as efficient for sharing information about wildfires and documenting management decision rationale. They identified emerging gaps in technical proficiency and the need for specialised training that creates high-level users to help guide teams using the program. Conclusions We offer suggestions about continued use of WFDSS including modifications to information distribution, revision of user roles, and expanded support for skills training. Implications Our results suggest that small changes to the WFDSS program and training curriculum may improve the experience of end-users and better match how they are using the program.
The Shr receptor from
Streptococcus pyogenes
uses a cap and release mechanism to acquire heme–iron from human hemoglobin
Authors: Macdonald Ramsay , Mahoney Brendan J. , Soule Jess , Goring Andrew K. , Ford Jordan , Loo Joseph A. , Cascio Duilio , Clubb Robert T.
Published: January 2023

Streptococcus pyogenes
(group A
Streptococcus
) is a clinically important microbial pathogen that requires iron in order to proliferate. During infections,
S. pyogenes
uses the surface displayed Shr receptor to capture human hemoglobin (Hb) and acquires its iron-laden heme molecules. Through a poorly understood mechanism, Shr engages Hb via two structurally unique N-terminal Hb-interacting domains (HID1 and HID2) which facilitate heme transfer to proximal NEAr Transporter (NEAT) domains. Based on the results of X-ray crystallography, small angle X-ray scattering, NMR spectroscopy, native mass spectrometry, and heme transfer experiments, we propose that Shr utilizes a “cap and release” mechanism to gather heme from Hb. In the mechanism, Shr uses the HID1 and HID2 modules to preferentially recognize only heme-loaded forms of Hb by contacting the edges of its protoporphyrin rings. Heme transfer is enabled by significant receptor dynamics within the Shr–Hb complex which function to transiently uncap HID1 from the heme bound to Hb’s β subunit, enabling the gated release of its relatively weakly bound heme molecule and subsequent capture by Shr’s NEAT domains. These dynamics may maximize the efficiency of heme scavenging by
S. pyogenes
, enabling it to preferentially recognize and remove heme from only heme-loaded forms of Hb that contain iron.
Spatial coding in the hippocampus and hyperpallium of flying owls
Authors: Agarwal Arpit , Sarel Ayelet , Derdikman Dori , Ulanovsky Nachum , Gutfreund Yoram
Published: January 2023

The elucidation of spatial coding in the hippocampus requires exploring diverse animal species. While robust place-cells are found in the mammalian hippocampus, much less is known about spatial coding in the hippocampus of birds. Here we used a wireless-electrophysiology system to record single neurons in the hippocampus and other two dorsal pallial structures from freely flying barn owls (
Tyto alba
), a central-place nocturnal predator species with excellent navigational abilities. The owl’s 3D position was monitored while it flew between perches. We found place cells—neurons that fired when the owl flew through a spatially restricted region in at least one direction—as well as neurons that encoded the direction of flight, and neurons that represented the owl’s perching position between flights. Many neurons encoded combinations of position, direction, and perching. Spatial coding was maintained stable and invariant to lighting conditions. Place cells were observed in owls performing two different types of flying tasks, highlighting the generality of the result. Place coding was found in the anterior hippocampus and in the posterior part of the hyperpallium apicale, and to a lesser extent in the visual Wulst. The finding of place-cells in flying owls suggests commonalities in spatial coding across mammals and birds.
SARS-CoV-2 evolution influences GBP and IFITM sensitivity
Authors: Mesner Dejan , Reuschl Ann-Kathrin , Whelan Matthew V. X. , Bronzovich Taylor , Haider Tafhima , Thorne Lucy G. , Ragazzini Roberta , Bonfanti Paola , Towers Greg J. , Jolly Clare
Published: January 2023

SARS-CoV-2 spike requires proteolytic processing for viral entry. A polybasic furin-cleavage site (FCS) in spike, and evolution toward an optimized FCS by dominant variants of concern (VOCs), are linked to enhanced infectivity and transmission. Here we show interferon-inducible restriction factors Guanylate-binding proteins (GBP) 2 and 5 interfere with furin-mediated spike cleavage and inhibit the infectivity of early-lineage isolates Wuhan-Hu-1 and VIC. By contrast, VOCs Alpha and Delta escape restriction by GBP2/5 that we map to the spike substitution D614G present in these VOCs. Despite inhibition of spike cleavage, these viruses remained sensitive to plasma membrane IFITM1, but not endosomal IFITM2 and 3, consistent with a preference for TMPRSS2-dependent plasma membrane entry. Strikingly, we find that Omicron is unique among VOCs, being sensitive to restriction factors GBP2/5, and also IFITM1, 2, and 3. Using chimeric spike mutants, we map the Omicron phenotype and show that the S1 domain determines Omicron’s sensitivity to GBP2/5, whereas the S2’ domain determines its sensitivity to endosomal IFITM2/3 and preferential use of TMPRSS2-independent entry. We propose that evolution of SARS-CoV-2 for the D614G substitution has allowed for escape from GBP restriction factors, but the selective pressures on Omicron for spike changes that mediate antibody escape, and altered tropism, have come at the expense of increased sensitivity to innate immune restriction factors that target virus entry.
A minimal physics-based model for musical perception
Authors: Mozaffari Kosar , Ahmadpoor Fatemeh , Deng Qian , Sharma Pradeep
Published: January 2023

Some people, entirely untrained in music, can listen to a song and replicate it on a piano with unnerving accuracy. What enables some to “hear” music so much better than others? Long-standing research confirms that part of the answer is undoubtedly neurological and can be improved with training. However, are there structural, physical, or engineering attributes of the human hearing mechanism apparatus (i.e., the hair cells of the internal ear) that render one human innately superior to another in terms of propensity to listen to music? In this work, we investigate a physics-based model of the electromechanics of the hair cells in the inner ear to understand why a person might be physiologically better poised to distinguish musical sounds. A key feature of the model is that we avoid a “black-box” systems-type approach. All parameters are well-defined physical quantities, including membrane thickness, bending modulus, electromechanical properties, and geometrical features, among others. Using the two-tone interference problem as a proxy for musical perception, our model allows us to establish the basis for exploring the effect of external factors such as medicine or environment. As an example of the insights we obtain, we conclude that the reduction in bending modulus of the cell membranes (which for instance may be caused by the usage of a certain class of analgesic drugs) or an increase in the flexoelectricity of the hair cell membrane can interfere with the perception of two-tone excitation.
Boundary conditions for AdS2 dilaton gravity
Authors: Valcárcel Carlos
Published: January 2023

We study a bi-parametric family of dilaton gravity models with constant and negative curvature. This family includes the Jackiw–Teitelboim gravity and the Liouville gravity model induced by a bosonic string. Furthermore, this family is conformally equivalent to the hyperbolic dilaton models. We propose boundary conditions in the Fefferman–Graham and in the Eddington–Finkelstein gauge. We check the consistency of the asymptotic conditions by computing the entropy of their black hole solution.
Circular Airy-like beams through leaky-wave antennas
Authors: Benedetti Alessio , Comite Davide , Fuscaldo Walter , Baccarelli Paolo , Galli Alessandro , Burghignoli Paolo
Published: January 2023

A planar nonuniform radially periodic leaky-wave antenna is proposed for the generation of circular, azimuthally symmetric Airy beams. The design is compact and low cost, and it is excited by an integrated coaxial cable. An annular metal strip grating is considered as background structure, designed to support a fast, backward, radially propagating space harmonic, which is capable of generating nondiffracting fields. The period and slots width are then properly modulated to synthesize the relevant Airy-like aperture-field distribution. An approximate formula is proposed to describe the aperture field, which is then used to retrieve the pattern of the annular strips. The near field produced by the structure is evaluated through the radiation integral, and validated by means of numerical full-wave simulations.
Prediction of superconductivity in Li, K, Ca, and Sr-intercalated blue phosphorene bilayer using first-principle calculations
Authors: Er-Rahmany S , Loulidi M , El Kenz A , Benyoussef A , Balli M , Azzouz M
Published: January 2023

Blue phosphorene is an interesting two-dimensional (2D) material, which has attracted the attention of researchers, due to its affluent physical and chemical properties. In recent years, it was discovered that the intercalation of alkali metals and alkaline earth metals in 2D materials may lead to conventional Bardeen–Cooper–Schrieffer (BCS) superconductivity. In this work, the electronic structure, phonon dispersion, Eliashberg spectral function, electron–phonon coupling (EPC), and the critical temperature of blue phosphorene bilayer intercalated by alkali metals (Li, and K) and alkaline earth metals (Ca, and Sr) for both AB and AC stacking orders are studied using the density functional theory and the density functional perturbation theory, within the generalized gradient approximation with van der Waals correction. The present work shows that the blue phosphorene bilayer is dynamically stable in AB stacking for Li and AC stacking for K, Ca, and Sr, and after intercalation, it transforms from a semiconductor to a metal owing to charge transfer between intercalated atoms and phosphorene. Furthermore, the EPC constant and the critical temperature are higher than those of 2D BCS-type superconductors. They are about 3 and 24.61 K respectively for K-intercalated blue phosphorene bilayer. Thus, our results suggest that blue phosphorene is a good candidate for a superconductor.
Development of size-specific dose estimates for common computed tomography examinations: a study in Ghana
Authors: Ohene-Botwe Benard , Anim-Sampong Samuel , Nkansah Josephine
Published: January 2023

This study determined the size-specific dose estimate (SSDE) of computed tomography (CT) examinations and derived mathematical expressions for dose output estimation and optimization in a teaching hospital in Ghana. Demographic and scanner output indices, including CT dose index (CTDIvol) and dose length product for adult head, chest and abdominopelvic (ABP) CT examinations carried out at the hospital from 2018 to 2020, were retrieved from the picture archiving and communication system of the CT scanner machine. Other indices such as the antero-posterior diameter (D
AP), lateral diameter (D
L) and diagonal diameter (D
dia) of the patients’ bodies were measured on the mid-slice axial image using a digital caliper. The effective diameter (D
eff) was then calculated as the square root of the product of the D
AP and D
L. The SSDEs were calculated as the product of the CTDIvol and the size-specific conversion factors obtained from Report 204 of the American Association of Physicists in Medicine. Regression analyses were performed to find the relationship between SSDE and the various parameters to derive mathematical equations for the dose estimations. There were more female samples (n= 468, 56.3%) than male samples (n = 364, 43.7%) for each CT procedure. The SSDEs and size-specific diagnostic reference levels (SSDRLs) were: head (83.9 mGy; 86.9 mGy), chest (8.1 mGy; 8.7 mGy) and ABP (8.4 mGy; 9.2 mGy). The variations between CTDIvol and SSDEs for head (2.50%), chest (25.9%), and ABP (26.2%) showed an underestimation of radiation dose to patients, especially in chest and ABP examinations, if CTDIvol is used to report patient doses. The SSDEs of the chest and ABP CT examinations showed linear correlations with the CTDIvol. The estimated values could be used to optimize radiation doses in the CT facility. The SSDE and SSDRLs for head, chest and ABP CT examinations have been developed at a teaching hospital in Ghana. The SSDEs of chest and ABP examinations showed linear correlations with the CTDIvol and hence can be calculated using the mathematically derived equations in the study.
Prospects on ultrasound measurement techniques with optical fibers
Authors: Bao Xiaoyi
Published: January 2023

Ultrasound sensors have been widely used in medical imaging, as well as structural health monitoring (SHM) and non-destructive testing (NDT) in civil and mechanical structures. Covering entire structures and imaging large areas requires multiplexing of many ultrasound sensors with single readout instrument, which can be difficult for traditional piezoelectric transducers. Optical fiber-based sensors offer numerous advantages such as being lightweight, small, the ability to be embedded, immunity to electro-magnetic interference, and the ability to be multiplexed and distributed ultrasound sensors. Fiber ultrasound sensors are regarded as an ideal sensing solution for SHM and NDT, and even most recently for medical imaging due to its broadband ultrasound response and distributed capability. Micro and nanofibers are made smaller than telecom fibers using a wider selection of sensing materials with higher bending capability, which makes them ideal for high frequency (hundreds of MHz) ultrasound detection of micrometer cracks and imaging biological tissues. New optical materials and fabrication techniques are shaping the future with exceptionally small ultrasound sensors and actuators, extending the range of applications in SHM, NDT and medical imaging with higher accuracy and better precision over larger areas.
Measuring timing properties of thermal infrared cameras
Authors: Schatz Volker
Published: January 2023

A measurement setup and method is presented that serves to determine constants characterising the timing behaviour of thermal infrared cameras. A continuously rotating chopper wheel is used to periodically obscure and reveal the cutout of a mask plate. The exposed fraction of the cutout is the main measured quantity. Irregularities in the chopper wheel are determined from timestamps of the light beam detectors in the chopper head. The method is suitable for both kinds of thermal cameras, cooled cameras and microbolometer cameras, and for both snapshot and rolling-frame cameras. Example results are presented for a cooled snapshot camera and a rolling-frame microbolometer camera.
Strip steel surface defect detecting method combined with a multi-layer attention mechanism network
Authors: Liu Guohua , Ma Qianwen
Published: January 2023

In the production of strip steel, defect detection is a crucial step. However, current inspection techniques frequently suffer from issues like low detection accuracy and subpar real-time performance. We provide a deep learning-based strip steel surface defect detection technique to address the aforementioned issues. The algorithm is also implemented in three specific ways: as the backbone, the neck, and the detection head. Backbone employs an enhanced cross stage partial in conjunction with ResNet to effectively mine defect information and minimize the issue of adjoining feature maps’ neighboring feature maps losing information. Neck is a better structure, we propose and use the dilated weighted across stages-feature pyramid network in the network to adjust the receptive field and attention weight preference of the output feature maps at different scales and to improve the utilization of defect features by the algorithm to enhance the detection of abnormal size defects. We use four detection heads in the detection head so that the network can learn the features of defects of various sizes. Finally, we use the decoupled head to separate the classification work from the regression work before combining the prediction. Two datasets of surface flaws in strip steel are used in our experiments (GC10-DET and NEU-DET). In addition, it has been shown that our proposed algorithm’s mAP in GC10-DET and NEU-DET reaches 79.93% and 72.76%, respectively, resulting in a better detection impact.
Multi-input parallel graph neural network for semi-supervised rolling bearing fault diagnosis
Authors: Bao Shouyang , Feng Jing , Xu Xiaobin , Hou Pingzhi , Zhang Zhenjie , Meng Jianfang , Steyskal Felix
Published: January 2023

Rolling bearing fault diagnosis is the key technology to ensure the reliable, efficient and sustainable operation of rotating machinery. Many fault diagnosis methods have been proposed based on vibration signal analysis from the perspective of data-driven analytics. However, these methods normally take signals of multiple sensors as a whole for feature extraction without considering the relationship among samples. This drawback leads to insufficient feature mining, thereby affecting the accuracy of fault diagnosis. Moreover, these methods need large numbers of labeled samples to achieve high diagnosis accuracy, which requires extensive human labor and is impractical in many real-world applications. To address these issues, a semi-supervised rolling bearing fault diagnosis method based on multi-input parallel graph neural network is proposed in this paper. In the proposed model, signals of multiple sensors are treated separately; thus, features will be extracted parallelly in a more sufficient way. Then, signals of each sensor are constructed into a graph based on limited-radius nearest neighbor, which will add extra relationship information to aid in fault diagnosis. In addition, with the implementation of graph convolutional neural network, the proposed method is able to achieve a more accurate diagnosis than the comparison methods in the case of few labeled data. Finally, the proposed model is evaluated on rolling bearing dataset provided by Case Western Reserve University. Compared with some classical fault diagnosis methods, the proposed model can improve the diagnosis accuracy up to more than 99% even when the proportion of training samples is only 20%.
Effect of discreteness and misalignment on magnetic field and charged particle confinement in CFQS quasi-axisymmetric stellarator
Authors: Xiong Guozhen , Xu Yuhong , Isobe Mitsutaka , Shimizu Akihiro , Ogawa Kunihiro , Kinoshita Shigeyoshi , Liu Haifeng , Wang Xianqu , Cheng Jun , Liu Hai , Huang Jie , Zhang Xin , Zhang Yichao , Yin Dapeng , Wang Anzhu , Okamura Shoichi , Tang Changjian
Published: January 2023

The Chinese first quasi-axisymmetric stellarator (CFQS), which will be the first quasi-axisymmetric (QA) stellarator in the world, is now under construction. The primary task of the CFQS project is to realize a QA configuration and to examine its physical properties. Based on this task, two important issues were investigated in this work in order to estimate the robustness of the CFQS design from a physical perspective. One was the toroidal field (TF) ripple due to the discreteness of modular coils (MCs) which could potentially degrade the charged particle confinement in the CFQS configuration. The other was a possible MC misalignment in the assembly that would affect the magnetic field and charged particle confinement in the CFQS. Moreover, since the stellarator symmetry might be broken by the MC misalignment, such a case was also investigated in this work. By performing a magnetic field line tracing and charged particle orbit tracing calculation, it was found that the TF ripple does not affect the confinement property significantly and the magnetohydrodynamics equilibrium was robust against possible MC misalignments. These results are helpful in defining the reasonable tolerance of assembly accuracy.
Noise tailoring for robust amplitude estimation
Authors: Dalal Archismita , Katabarwa Amara
Published: January 2023

A universal fault-tolerant quantum computer holds the promise to speed up computational problems that are otherwise intractable on classical computers; however, for the next decade or so, our access is restricted to noisy intermediate-scale quantum (NISQ) computers and, perhaps, early fault tolerant (EFT) quantum computers. This motivates the development of many near-term quantum algorithms including robust amplitude estimation (RAE), which is a quantum-enhanced algorithm for estimating expectation values. One obstacle to using RAE has been a paucity of ways of getting realistic error models incorporated into this algorithm. So far the impact of device noise on RAE is incorporated into one of its subroutines as an exponential decay model, which is unrealistic for NISQ devices and, maybe, for EFT devices; this hinders the performance of RAE. Rather than trying to explicitly model realistic noise effects, which may be infeasible, we circumvent this obstacle by tailoring device noise using randomized compiling to generate an effective noise model, whose impact on RAE closely resembles that of the exponential decay model. Using noisy simulations, we show that our noise-tailored RAE algorithm is able to regain improvements in both bias and precision that are expected for RAE. Additionally, on IBM’s quantum computer ibmq_belem our algorithm demonstrates advantage over the standard estimation technique in reducing bias. Thus, our work extends the feasibility of RAE on NISQ computers, consequently bringing us one step closer towards achieving quantum advantage using these devices.
Spatio-temporal patterns of non-autonomous systems on hypergraphs: Turing and Benjamin–Feir mechanisms
Authors: Wang Wen , Liu Shutang
Published: January 2023

This paper examines the Turing patterns and the spatio-temporal chaos of non-autonomous systems defined on hypergraphs. The analytical conditions for Turing instability and Benjamin–Feir instability are obtained by linear stability analysis using new comparison principles. The comparison with pairwise interactions is presented to reveal the effect of higher-order interactions on pattern formation. In addition, numerical simulations due to different non-autonomous mechanisms, such as time-varying diffusion coefficients, time-varying reaction kinetics and time-varying diffusion coupling are provided respectively, which verifies the efficiency of theoretical results.
Novel solutions of (2+1) dimensional modified Bogoyavlenskii’s breaking soliton equation with variable coefficients
Authors: Wang Shaofu
Published: January 2023

In this paper, by using the homogeneous equilibrium method, the exact solutions of a modified Bogoyavlenskii’s breaking soliton equation are derived and the soliton solutions with arbitrary functions are constructed. Then, the basic law of interaction between the different solitons are revealed and some new local structures are addressed and discussed. The periodic solitons, parabolic solitons and folded solitons of arbitrary shape propagating with variable speed are considered. It is helpful not only to verify the numerical solution and analyze the stability of the solution, but also to understand the dynamics of the high dimensional nonlinear wave field.
A new general approach for obtaining matrix product operators for spin Hamiltonians with periodic boundary conditions
Authors: Solanki Payal D , Ramkarthik M S
Published: January 2023

This article concerns the matrix product operators for one-dimensional spin Hamiltonians under open and periodic boundary conditions. A novel approach called ‘the dynamics of blocks’ is proposed to obtain the matrix product operators in the case of Hamiltonians with periodic boundary conditions. This approach works universally for any Hamiltonian with two-particle as well as single-particle interactions. The main significance of the proposed approach is that, the dimensions of the matrix product operators obtained are the same for both open and periodic boundary conditions. This method gives us a generic way of constructing MPOs for any Hamiltonian with arbitrary neighboring interactions, immaterial of how the interaction strength falls. A general numerical implementation of the ‘dynamics of blocks’ method is also carried out. The DMRG algorithm was implemented, and the ground state eigenvalue was obtained using these MPOs to numerically validate the method.
Assessment of black rot development on apple surface using laser biospeckle technique
Authors: Koley Chhanda , Das Rittik , Nirala Anil Kumar
Published: January 2023

In our present study, the laser biospeckle technique has been applied to monitor the spread of black rot fungal disease and evaluate the infected area on apple surface for the first time to the best of our knowledge. Image processing algorithms such as inertia moment (IM), absolute value of differences (AVD) and spatial-temporal speckle correlation show the reduction of biospeckle activity of the black rot infected apples in comparison to that of the healthy apples with increase in time, once the visible symptom of the disease sets in. Spectral activity maps obtained using Fujii, inverse Fujii and parameterized Fujii show the spread of this infection with the progression of day. Under exposition test and histogram plot have been used to evaluate the increase of darkness of the infected apple with the progression of day and the results have come out as a replica of the change of colour of the region of interest. % biospeckle activity loss on the final day of the experiment has been found to be 17.83% and 11.91% for healthy apples & 92.42% and 78.63% for infected apples using IM and AVD respectively. An increase in the infected area and % increase in infected area of the region of interest on the image plane has been determined to be 0.33 mm2 and 58.57% respectively on the final day of the experiment.
Quantum gravity lights up spinning black holes
Authors: Eichhorn Astrid , Held Aaron
Published: January 2023

Quantum-gravity effects in black holes are generally expected to be unobservable if they set in at transplanckian curvature scales. Here, we challenge this expectation. A near-critical spin parameter can serve as a lever arm that translates Planckian quantum-gravity effects to a global change in the spacetime: the horizon dissolves and the black hole “lights up”.

We investigate this transition between a black hole and a horizonless spacetime and find that additional lensing features appear instantaneously, when the quantum-gravity effect is added.
In the presence of an accretion disk, a second set of internal photon rings appears in addition to the exponentially stacked set of external photon rings.
The internal and external photon rings merge into cresent-like features as a function of increasing spin parameter. We explore how these simulated images would be reconstructed by a radio-very-long-baseline-interferometry array like the Event Horizon Telescope. We find that a future next-generation Event Horizon Telescope may be sensitive to the additional lensing features.
Full-shape BOSS constraints on dark matter interacting with dark radiation and lifting the S8
tension
Authors: Rubira Henrique , Mazoun Asmaa , Garny Mathias
Published: January 2023

In this work we derive constraints on interacting dark matter-dark radiation models from a full-shape analysis of BOSS-DR12 galaxy clustering data, combined with Planck legacy cosmic microwave background (CMB) and baryon acoustic oscillation (BAO) measurements. We consider a set of models parameterized within the effective theory of structure formation (ETHOS), quantifying the
lifting of the S8
tension in view of KiDS weak-lensing results. The most favorable scenarios point to a fraction f ∼ 10-100% of interacting dark matter as well as a dark radiation temperature that is smaller by a factor ξ ∼ 0.1-0.15 compared to the CMB, leading to a reduction of the tension to the ∼ 1σ level.
The temperature dependence of the interaction rate favored by relaxing the S8
tension is realized for a weakly coupled unbroken non-Abelian SU(N) gauge interaction in the dark sector.
To map our results onto this SU(N) model, we compute higher-order corrections due to Debye screening. We find
a lower bound αd
≡ gd

2/(4π) ≳ 10-8 (10-9) for dark matter mass 1000 (1) GeV for relaxing the S8
tension, consistent with upper bounds from galaxy ellipticities and compatible with self-interactions relevant for small-scale structure formation.
Instability in axion inflation with strong backreaction from gauge modes
Authors: Peloso Marco , Sorbo Lorenzo
Published: January 2023

We perform an analytical study of the stability of the background
solution [1] of the model in which an inflaton, through an axionic coupling to a
U(1) gauge field, causes an amplification of the gauge field modes that strongly backreact on
its dynamics. To this goal, we study the evolution of the gauge field modes coupled to the
inflaton zero mode, treating perturbatively the deviation of the inflaton velocity from its
mean-field value. As long as the system is in the strong backreaction regime we find that the
inflaton velocity performs oscillations of increasing amplitude about the value it would have in
the approximation of constant velocity, confirming an instability that has been observed in
numerical studies.
Local variations of charge radii for nuclei with even Z from 84 to 120
Authors: An Rong , Dong Xiao-Xu , Cao Li-Gang , Zhang Feng-Shou
Published: January 2023

Pronounced changes of nuclear charge radii provide a stringent benchmark on the theoretical models and play a vital role in recognizing various nuclear phenomena. In this work, the systematic evolutions of nuclear charge radii along even Z = 84–120 isotopic chains are first investigated by the recently developed new ansatz under the covariant density functional. The calculated results show that the shell closure effects of nuclear charge radii appear remarkably at the neutron numbers N = 126 and 184. Interestingly, the arch-like shapes of charge radii between these two strong neutron-closed shells are naturally observed. Across the N = 184 shell closure, the abrupt increase in charge radii is still evidently emerged. In addition, the rapid raise of nuclear charge radii from the neutron numbers N = 138 to N = 144 is disclosed clearly in superheavy regions due to the enhanced shape deformation.
Decoding spatial locations from primate lateral prefrontal cortex neural activity during virtual navigation
Authors: Johnston Renée , Abbass Mohamad , Corrigan Benjamin , Gulli Roberto , Martinez-Trujillo Julio , Sachs Adam
Published: January 2023

Objective. Decoding the intended trajectories from brain signals using a brain-computer interface system could be used to improve the mobility of patients with disabilities. Approach. Neuronal activity associated with spatial locations was examined while macaques performed a navigation task within a virtual environment. Main results. Here, we provide proof of principle that multi-unit spiking activity recorded from the lateral prefrontal cortex (LPFC) of non-human primates can be used to predict the location of a subject in a virtual maze during a navigation task. The spatial positions within the maze that require a choice or are associated with relevant task events can be better predicted than the locations where no relevant events occur. Importantly, within a task epoch of a single trial, multiple locations along the maze can be independently identified using a support vector machine model. Significance. Considering that the LPFC of macaques and humans share similar properties, our results suggest that this area could be a valuable implant location for an intracortical brain-computer interface system used for spatial navigation in patients with disabilities.