bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parsec scales of carbon chain and complex organic molecules in AFGL 2591 and IRAS 20126
Authors: Freeman P. , Bottinelli S. , Plume R. , Caux E. , Monaghan C. , Mookerjea B. 
Published: August 2023

Context. There is a diverse chemical inventory in protostellar regions leading to the classification of extreme types of systems. Warm carbon chain chemistry sources, for one, are the warm and dense regions near a protostar containing unsaturated carbon chain molecules. Since the presentation of this definition in 2008, there is a growing field to detect and characterise these sources. The details are lesser known in relation to hot cores and in high-mass star-forming regions - regions of great importance in galactic evolution.
Aims. To investigate the prevalence of carbon chain species and their environment in high-mass star-forming regions, we have conducted targeted spectral surveys of two sources in the direction of Cygnus X - AFGL 2591 and IRAS 20126+4104.
Methods. We observed these sources in frequency ranges around 85, 96, and 290 GHz with the Green Bank Telescope and the IRAM 30m Telescope. We have constructed a local thermodynamic equilibrium (LTE) model using the observed molecular spectra to determine the physical environment in which these molecules originate. We map both the observed spatial distribution and the physical parameters found from the LTE model. We also determine the formation routes of these molecules in each source using the three-phase NAUTILUS chemical evolution code.
Results. We detect several lines of propyne, CH3CCH, and cyclopropenylidene, c-C3H2 as tracers of carbon chain chemistry, as well as several lines of formaldehyde, H2CO, and methanol, CH3OH, as a precursor and a tracer of complex organic molecule chemistry, respectively. We find excitation temperatures of 20−30 K for the carbon chains and 8−85 K for the complex organics. The observed abundances, used as input for the chemical evolution code, are 10−9 to 10−10 for both CH3CCH and CH3OH. The CH3CCH abundances are reproduced by a warm-up model, consistent with warm carbon chain chemistry, while the observed CH3OH abundances require a shock mechanism sputtering the molecules into the gas phase.
Conclusions. Single-dish observations are useful for studying the envelope-scale chemistry of star-forming regions, including mechanisms such as warm carbon chain chemistry. As well, LTE models lend well to the wide-band maps obtained from these telescopes. The physical and chemical environment determined for complex hydrocarbons and complex organics lends understanding to high-mass star formation.
Intramolecular Asymmetric Cyclopropanation Using Air-Stable Alkylboronic Esters
Authors: Vedani Luca , Gnägi-Lux Manuel , Dénès Fabrice , Renaud Philippe 
Published: August 2023

AbstractThe preparation of polysubstituted bicyclo[3.1.0]hexanes starting from air-stable substituted pent-4-en-1-ylboronic acid esters has been investigated. The method involves a Matteson homologation with LiCHCl2, leading to 1-chlorohex-5-en-1-ylboronic acid ester intermediates. The subsequent intramolecular cyclopropanation step was performed in a one-pot process. With pinacol boronic esters, the cyclopropanation step was either performed thermally at 140 °C or at 70 °C after in situ transesterification to form a catechol boronic ester. This last approach is suitable for the preparation of enantioenriched bicyclo[3.1.0]hexanes using either chiral-auxiliary control or by taking advantage of the sparteine-controlled enantioselective boroalkylation of alcohols.
The Clinical Trials Assistance Pilot: reducing the financial burden of cancer clinical trials for patients in regional New South Wales
Authors: Luiten-Apirana Pareoranga , Gendi Monica , Bernard Jai , Li Zhicheng , Edge Rhiannon , Gellert Bradley , Miller Annie , Mury Maria , Sansey Niki , Jasicki Lindsey , Stolp Sean 
Published: August 2023

Objective This study investigated whether the provision of financial assistance to patients living in regional New South Wales influenced patients’ decisions to participate in a cancer clinical trial (cancer treatment or supportive care) and resulted in improved psychosocial outcomes. Methods Administrative data were collected from participants, including demographics, travel distances and the value of financial support provided. Qualitative interviews were then conducted with a subset of consenting patients who received financial assistance for a clinical trial. Results Sixty-four patients with cancer received financial support for a clinical trial, 27 (42%) of whom were interviewed. Participants whose distance to a trial site was over 400 km received almost three times as much financial support (M = A$3194.20, s.d. = A$1597.60) as participants whose distance to a trial site was between 50 and 100 km (M = A$1116.29, s.d. = $A1311.23). Half of participants indicated that receiving financial assistance influenced their decision to participate in a clinical trial, and most indicated the support alleviated the financial burden of clinical trial participation. Conclusions The provision of financial assistance to patients living in regional areas may reduce inequities in cancer clinical trial participation and improve psychosocial outcomes.
A note on the Kaluza–Klein theory
Authors: Li Li-Xin 
Published: August 2023

Abstract
We show that the Kaluza–Klein (KK) theory contains a fundamental problem: The four-dimensional metric tensor and the electromagnetic potential vector assumed in the KK theory belong to four-dimensional vector spaces that are not integrable in general, resulting that the four-dimensional physical variables and the corresponding field equations derived from the five-dimensional Einstein field equation (i.e. the four-dimensional Einstein field equation and the Maxwell equations) are not defined on a four-dimensional submanifold. That is, the four-dimensional spacetime assumed in the KK theory does not exist. No satisfactory solutions are found within the KK formalism. Perhaps the best approach to fix the problem is giving up the KK theory and looking for a new unified scheme for gravitational and electromagnetic interactions in the framework of a spacetime with extra dimensions, as having already been explored in some literature.
A SINS/GNSS/2D-LDV integrated navigation scheme for unmanned ground vehicles
Authors: Xiang Zhiyi , Zhang Tao , Wang Qi , Jin Shilong , Nie Xiaoming , Duan Chengfang , Zhou Jian 
Published: August 2023

Abstract
In recent years, unmanned autonomous driving technology has attracted increasing attention from people, and become a research hotspot. Currently, the integration of strapdown inertial navigation system (SINS) and global navigation satellite systems (GNSSs) is the most common and effective navigation and positioning scheme for unmanned ground vehicles (UGVs) and unmanned aerial vehicles. However, this integrated system is unable to maintain a reliable positioning solution in challenging environments due to the inherent weakness of GNSS signals and the accumulation of SINS positioning errors over time. To address this issue, this paper proposes an integrated scheme based on an asynchronous Kalman filter for SINS, GNSS and two-dimensional (2D) laser Doppler velocimeter (LDV). In the proposed scheme, the SINS and 2D-LDV are tightly coupled to improve the robustness of the integrated system, and the error parameters between the 2D-LDV and the SINS are calibrated in real time during the validity of the GNSS signal. In addition, the designed asynchronous Kalman filter method evaluates the validity of the GNSS and 2D-LDV measurements in real time based on Mahalanobis distance of innovation vector and statistical property principle. Two groups of long-distance, high-mobility vehicle experiments conducted in challenging environments verify the validity of the proposed scheme. The experimental results show that the proposed SINS/GNSS/2D-LDV integrated navigation scheme has good environmental adaptability and reliability, and can maintain high horizontal and vertical positioning accuracy despite frequent GNSS signal failures, which can meet the needs of UGVs.
Effects of vacancy concentration on the edge dislocation motion in copper by atomic simulations
Authors: Chen Wenjin , Li Run , Yao Songlin , Zhu Wenjun , Li Xiaofan , Fang Jingzhong , Wang Kun 
Published: August 2023

Abstract
Nonequilibirum vacancy concentration widely appears in crystals under many extreme loading conditions, but receives relatively few attentions. In this work, we systematically explore the influence of a serial of different vacancy concentrations on the edge dislocation motion in copper using molecular dynamics (MD) simulations. Our result shows that the vacancy would hinder the dislocation motion, but the mechanism depends on the detailed dislocation motion regions. In thermally activated region, its influence is mainly reflected by modifying the dynamic and static threshold stresses required for edge dislocation initiation and continuous motion. In the linear region, the hindering mechanism is gradually transformed from phonon damping to vacancy pinning with the increasing vacancy concentration. In contrasts, the dislocation structure is almost unchanged under different vacancy concentrations in the non-linear region. Under high applied stress, high vacancy concentration will cause the dislocation velocity to jump back and forth between transonic and subsonic velocities more frequently. It has been attributed to the reactions between the dislocation and vacancies. The latter may result in dislocation local constriction and climbing. Moreover, a mobility equation suitable for describing edge dislocations at different non-equilibrium vacancy concentrations is proposed, which fits the MD results well. Finally, the roles of the nonequilibirum vacancy concentration on the edge dislocation motion is interpreted using the degrading elastic property and stacking fault energy.
Quantum dots derived from two-dimensional transition metal dichalcogenides: synthesis, optical properties and optoelectronic applications
Authors: Chiu Ching-Hsueh , Chen Yu-Ting , Shen Ji-Lin 
Published: August 2023

Abstract
Zero-dimensional transition metal dichalcogenides (TMD) quantum dots (QDs) have attracted a lot of attention due to their interesting fundamental properties and various applications. Compared to TMD monolayers, the QD counterpart exhibits larger values for direct transition energies, exciton binding energies, absorption coefficient, luminescence efficiency, and specific surface area. These characteristics make them useful in optoelectronic devices. In this review, recent exciting progress on synthesis, optical properties, and applications of TMD QDs is highlighted. The first part of this article begins with a brief description of the synthesis approaches, which focus on microwave-assistant heating and pulsed laser ablation methods. The second part introduces the fundamental optical properties of TMD QDs, including quantum confinement in optical absorption, excitation-wavelength-dependent photoluminescence, and many-body effects. These properties are highlighted. In the third part, we discuss lastest advancements in optoelectronic devices based on TMD QDs These devices include light-emitting diodes, solar cells, photodetectors, optical sensors, and light-controlled memory devices. Finally, a brief summary and outlook will be provided.
Maxwell–Bloch equations without spectral broadening: the long-time asymptotics of an input pulse in a long two-level laser amplifier
Authors: Kotlyarov Volodymyr , Minakov Oleksandr 
Published: August 2023

Abstract
We study the problem of propagation of an input electromagnetic pulse through a long two-level laser amplifier under trivial initial conditions. In this paper, we consider an unstable model described by the Maxwell–Bloch equations without spectral broadening. Previously, this model was studied by Manakov in (1982 Zh. Eksp. Teor. Fiz.
83 68–75) and together with Novokshenov in (1986 Teor. Mat. Fiz.
69 40–54). We consider this model in a more natural formulation as an initial-boundary (mixed) problem using a modern version of the inverse scattering transform method in the form of a suitable Riemann–Hilbert (RH) problem. The RH problem arises as a result of applying the Fokas–Its method of simultaneous analysis of the corresponding spectral problems for the Ablowitz–Kaup–Newell–Segur equations. This approach makes it possible to obtain rigorous asymptotic results at large times, which differ significantly from the previous ones. Differences take place both near the light cone and in the tail region, where a new type of solitons is found against an oscillating background. These solitons are physically relevant, their velocities are smaller than the speed of light. The number of such solitons can be either finite or infinite (in the latter case, the set of zeros has a condensation point at infinity). Such solitons cannot be reflectionless, they are generated by zeros of the reflection coefficient of the input pulse (and not by poles of the transmission coefficient). Thus our approach shows the presence of a new phenomenon in soliton theory, namely, the boundary condition (input pulse) of a mixed problem under trivial initial conditions can generate solitons due to the zeros of the reflection coefficient, while the poles of the transmission coefficient do not contribute to the asymptotics of the solution.
D-SAT: dual semantic aggregation transformer with dual attention for medical image segmentation
Authors: Li Haiyan , Ding Jiayu , Shi Xin , Zhang Qi , Yu Pengfei , Li Hongsong 
Published: August 2023

Abstract

Objective. Medical image segmentation is significantly essential to assist clinicians in facilitating a quick and accurate diagnoses. However, most of the existing methods are still challenged by the loss of semantic information, blurred boundaries and the huge semantic gap between the encoder and decoder. Approach. To tackle these issues, a dual semantic aggregation transformer with dual attention is proposed for medical image segmentation. Firstly, the dual-semantic feature aggregation module is designed to build a bridge between convolutional neural network (CNN) and Transformer, effectively aggregating CNN’s local feature detail ability and Transformer’s long-range modeling ability to mitigate semantic information loss. Thereafter, the strip spatial attention mechanism is put forward to alleviate the blurred boundaries during encoding by constructing pixel-level feature relations across CSWin Transformer blocks from different spatial dimensions. Finally, a feature distribution gated attention module is constructed in the skip connection between the encoder and decoder to decrease the large semantic gap by filtering out the noise in low-level semantic information when fusing low-level and high-level semantic features during decoding. Main results. Comprehensive experiments conducted on abdominal multi-organ segmentation, cardiac diagnosis, polyp segmentation and skin lesion segmentation serve to validate the generalization and effectiveness of the proposed dual semantic aggregation transformer with dual attention (D-SAT). The superiority of D-SAT over current state-of-the-art methods is substantiated by both subjective and objective evaluations, revealing its remarkable performance in terms of segmentation accuracy and quality. Significance. The proposed method subtly preserves the local feature details and global context information in medical image segmentation, providing valuable support to improve diagnostic efficiency for clinicians and early disease control for patients. Code is available at https://github.com/Dxkm/D-SAT.
Bolt tightness monitoring using multiple reconstructed narrowband Lamb waves combined with piezoelectric ultrasonic transducer
Authors: Li Xiuquan , Liu Gaoxi , Sun Qiaolei , Chen Hongbing , Chen Lin , Zhang Minghui , Sun Xiangtao 
Published: August 2023

Abstract
Narrowband tone burst excitation with a carefully selected frequency is generally utilized to generate Lamb waves for mode purity, dispersion diminution and signal interpretability. Narrowband excitation exhibits saturation phenomenon and even non-monotonic trends with the development of bolt looseness. In this research, a piezoelectric ultrasonic transducer with high signal-to-noise ratio is designed and fabricated for bolt tightness monitoring. The chirp signal is utilized to drive the actuator to generate broadband Lamb waves in the connected plate, and a transfer function-based signal reconstruction algorithm is innovatively proposed to extract narrowband tone burst responses with different center frequencies from the broadband chirp response for bolt tightness monitoring. The leaked wave energy-based bolt tightness indexes (TIs) are calculated based on the extracted multiple tone burst responses and a feature-level data fusion strategy is proposed to combine the TIs for exploiting the merits of different-frequency inspecting waves for different bolt tightness conditions. The fused TI not only presents a monotonic tendency with the increasing of bolt tightness, but also tackles the low sensitivity of narrowband Lamb waves for embryo bolt looseness. The proposed method contributes a novel and stable scheme for bolt tightness monitoring and opens a new perspective for damage evaluation of structures.
Controlling qubit-oscillator systems using linear parameter sweeps
Authors: Ashhab Sahel , Fuse Tomoko , Yoshihara Fumiki , Kim Sunmi , Semba Kouichi 
Published: August 2023

Abstract
We investigate the dynamics of a qubit-oscillator system under the influence of a linear sweep of system parameters. We consider two main cases. In the first case, we consider sweeping the parameters between the regime of a weakly correlated ground state and the regime of a strongly correlated ground state, a situation that can be viewed as a finite-duration quench between two phases of matter: the normal phase and the superradiant phase. Excitations are created as a result of this quench. We investigate the dependence of the excitation probabilities on the various parameters. We find a qualitative asymmetry in the dynamics between the cases of a normal-to-superradiant and superradiant-to-normal quench. The second case of parameter sweeps that we investigate is the problem of a Landau–Zener sweep in the qubit bias term for a qubit coupled to a harmonic oscillator. We analyze a theoretical formula based on the assumption that the dynamics can be decomposed into a sequence of independent Landau–Zener transitions. In addition to establishing the conditions of validity for the theoretical formula, we find that under suitable conditions, deterministic and robust multi-photon state preparation is possible in this system.
Diffusion in a bicrystal: effect of water uptake through grain boundary on the degradation of halide perovskites
Authors: Yang Fuqian 
Published: August 2023

Abstract
In this work, we investigate the diffusion in a bicrystal strip with a constant concentration of solute atoms/molecules on free surfaces to mimic the diffusion of water molecules in a bicrystal of halide perovskites. The effect of grain boundary diffusion is incorporated in the analysis, and the equation of mass transport in the grain boundary is derived without a time-derivative term. Using the equation of mass transport in the grain boundary, a closed-form solution of the spatiotemporal evolution of the concentration of solute atoms/molecules in the bicrystal is derived. Numerical analysis of the uptake of water in a methylammonium lead iodide (MAPbI3) bicrystal is performed. The degree of degradation of the MAPbI3 bicrystal due to the uptake of water is defined as the ratio of the diffusion length of water in one of the crystal in the bicrystal to the half width of the bicrystal. The numerical results reveal that the degree of degradation of the MAPbI3 bicrystal increases with the increase of the diffusion time and there exists effect of grain size on the degree of degradation of the MAPbI3 bicrystal. The time to reach the same degree of degradation due to the uptake of water is proportional to the width of the MAPbI3 bicrystal of the same thickness, in accord with the experimental results reported in literature. This result points to the need of producing halide perovskite films of large grain sizes in order to improve the structural stability and performance of perovskite-based photovoltaic cells by limiting the structural degradation induced by water diffusion.
Quantum decay of scalar and vector boson stars and oscillons into gravitons
Authors: Nakayama Kazunori , Takahashi Fuminobu , Yamada Masaki 
Published: August 2023

AbstractWe point out that a soliton such as an oscillon or boson star inevitably decays into gravitons through gravitational interactions. These decay processes exist even if there are no apparent self-interactions of the constituent field, scalar or vector, since they are induced by gravitational interactions. Hence, our results provide a strict upper limit on the lifetime of oscillons and boson stars including the dilute axion star. We also calculate the spectrum of the graviton background from decay of solitons.
Late vacuum choice and slow roll approximation in gravitational particle production during reheating
Authors: Cembranos Jose A.R. , Garay Luis J. , Parra-López Álvaro , Sánchez Velázquez Jose M. 
Published: August 2023

Abstract
In the transition between inflation and reheating, the curvature scalar typically
undergoes oscillations which have significant impact on the density of gravitationally produced
particles. The commonly used adiabatic vacuum prescription for the extraction of produced particle
spectra becomes a non-reliable definition of vacuum in the regimes for which this oscillatory
behavior is important. In this work, we study particle production for a scalar field non-minimally
coupled to gravity, taking into account the complete dynamics of spacetime during inflation and
reheating. We derive an approximation for the solution to the mode equation during the slow-roll
of the inflaton and analyze the importance of Ricci scalar oscillations in the resulting
spectra. Additionally, we propose a prescription for the vacuum that allows to safely extrapolate
the result to the present, given that the test field interacts only gravitationally. Lastly, we
calculate the abundance of dark matter this mechanism yields and compare it to observations.
PT-symmetric electronic dimer without gain material
Authors: Tagouegni Senghor , Fotsa-Ngaffo Fernande , Kenfack-Jiotsa Aurélien 
Published: August 2023

Abstract
In this paper, a way of building an electronic Parity Time (

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)-symmetric dimer without gain material is presented. This is achieved by capacitively coupling a pair of LZC circuits, each combining an inductance L, an imaginary resistance Z and a positive/negative capacitance C. We derive the effective Hamiltonian of the system, which commutes with the joint

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operator. The eigenspectrum displays spontaneous breaking points, where the system undergoes a transition from real to complex values. The transition points are imposed by the range value of the coupling thanks to the use of a negative capacitance. Temporal charge solutions and energy propagation are also analytically and numerically investigated, and the results are compatible. In the exact phase, these quantities oscillate, whereas in the broken phase, oscillations disappear, giving place to amplification. Our results pave the way to innovative

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-symmetric circuits. Applications could include, among others, optics, metamaterials, photonics and sensitive detection.