bluuebunny/crossref_metadata_2025_split huggingface dataset:
GammaBayes: a Bayesian pipeline for dark matter detection with CTA
Authors: Pinchbeck Liam , Thrane Eric , Balazs Csaba 
Published: May 2024

Abstract
We present GammaBayes, a Bayesian Python package for dark matter detection with the Cherenkov Telescope Array (CTA).
GammaBayes takes as input the CTA measurements of gamma rays and a user-specified dark-matter particle model.
It outputs the posterior distribution for parameters of the dark-matter model including the velocity-averaged cross section for dark-matter self interactions 〈σv〉 and the dark-matter mass mχ
.
It also outputs the Bayesian evidence, which can be used for model selection.
We demonstrate GammaBayes using 525 hours of simulated data, corresponding to 108 observed gamma-ray events.
The vast majority of this simulated data consists of noise, but 100000 events arise from the annihilation of scalar singlet dark matter with mχ
= 1 TeV.
We recover the dark matter mass within a 95% credible interval of mχ
∼ 0.96–1.07 TeV.
Meanwhile, the velocity averaged cross section is constrained to 〈σv〉 ∼ 1.4–2.1 × 10-25 cm3 s-1 (95% credibility).
This is equivalent to measuring the number of dark-matter annihilation events to be NS
∼ 1.1-0.2
+0.2 × 105.
The no-signal hypothesis 〈σv〉 = 0 is ruled out with about 5σ credibility.
We discuss how GammaBayes can be extended to include more sophisticated signal and background models and the computational challenges that must be addressed to facilitate these upgrades.
The source code is publicly available here.
Smooth vs instant inflationary transitions: steepest growth re-examined and primordial black holes
Authors: Cole Philippa S. , Gow Andrew D. , Byrnes Christian T. , Patil Subodh P. 
Published: May 2024

Abstract
Primordial black holes (PBHs) can be produced by a range of mechanisms in the early
universe. A particular formation channel that connects PBHs with inflationary phenomenology
invokes enhanced primordial curvature perturbations at small scales. In this paper, we examine how
rapidly the background can transition between different values of the parameters of the Hubble
hierarchy in the context of single-clock inflation, which must ultimately derive from a consistent
derivative expansion for the background inflaton field. We discuss artefacts associated with
instant or very rapid transitions, and consider the impact on the steepest power spectrum growth
and the formation of PBHs. In particular, we highlight the robustness of the k
4 steepest growth
previously found for single-field inflation with conservatively smoothed transitions and limits on
how much the amplitude of the power spectrum can grow, and demonstrate that the PBH mass
distribution is sensitive to the artefacts, which go away when the transitions are smoothed. We
also show that the mass distribution is relatively insensitive to the steepness of the growth and
subsequent decay of the power spectrum, depending primarily on the peak amplitude and the presence
of any plateaus that last more than an e-fold. The shape of the power spectrum can of course be
constrained by other tracers, and so understanding the physical limitations on its shape remains a
pertinent question.
Observational feasibility of 4D Einstein-Gauss-Bonnet cosmology: bouncing and non-bouncing universes
Authors: Khodabakhshi H. , Farhang M. , Lü H. 
Published: May 2024

Abstract
This paper analyzes the possibility of bouncing and non-bouncing universes in the framework of four-dimensional Einstein-Gauss-Bonnet (4D-EGB) gravity,
corresponding respectively to negative and positive coupling constants λ of the Gauss-Bonnet term. We also use the Horndeski-type scalar-tensor theory to assess the role of a scalar charge C as a geometrical contribution to the radiation in the Universe.
We modify the expansion history of the universe to allow for modifications induced by the 4D-EGB gravity.
Using Planck measurements of the cosmic microwave background anisotropies as well as various datasets of baryonic acoustic oscillations, we set the upper bounds λ ≤ 10-16(km/s/Mpc)-2 and λ ≤ 10-30(km/s/Mpc)-2 for the non-bouncing and bouncing scenarios.
The upper limit in the latter case is mainly driven by the requirement to conservatively respect the thermal history at energy scales of the standard model of particle physics.
We also find that the contribution of the geometrical radiation-like term of the model cannot exceed 10% of the current radiation in the Universe. The possibility of an early inflationary phase produced by a single scalar field is also studied and found to be feasible in both bouncing and non-bouncing scenarios.
This study shows the feasibility of a bouncing universe, even with a normal matter sector, in the 4D-EGB gravity. More theoretical investigation is required to further explore possible observational predictions of the model that can distinguish between general relativity and 4D-EGB gravity.
Decoherence out of fire: purity loss in expanding and contracting universes
Authors: Colas Thomas , de Rham Claudia , Kaplanek Greg 
Published: May 2024

Abstract
We investigate quantum decoherence in a class of models which interpolates between expanding (inflation) and contracting (ekpyrosis) scenarios. For the cases which result in a scale-invariant power spectrum, we find that ekpyrotic universes lead to complete decoherence of the curvature perturbation before the bounce. This is in stark contrast to the inflationary case, where recoherence has been previously observed in some situations. Although the purity can be computed for couplings of all sizes, we also study the purity perturbatively and observe that late-time (secular growth) breakdown of perturbation theory often occurs in these cases. Instead, we establish a simple yet powerful late-time purity resummation which captures the exact evolution to a remarkable level, while maintaining analytical control. We conclude that the cosmological background plays a crucial role in the decoupling of the heavy fields during inflation and alternatives.
Nonlinear gravitational waves in Horndeski gravity: scalar pulse and memories
Authors: Achour Jibril Ben , Gorji Mohammad Ali , Roussille Hugo 
Published: May 2024

Abstract
We present and analyze a new non-perturbative radiative solution of Horndeski gravity. This exact solution is constructed by a disformal mapping of a seed solution of the shift-symmetric Einstein-Scalar system belonging to the Robinson-Trautman geometry describing the gravitational radiation emitted by a time-dependent scalar monopole. After analyzing in detail the properties of the seed, we show that while the general relativity solution allows for shear-free parallel transported null frames, the disformed solution can only admit parallel transported null frames with a non-vanishing shear.
This result shows that, at the nonlinear level, the scalar-tensor mixing descending from the higher-order terms in Horndeski dynamics can generate shear out of a pure scalar monopole. We further confirm this analysis by identifying the spin-0 and spin-2 polarizations in the disformed solution using the Penrose limit of our radiative solution.
Finally, we compute the geodesic motion and the memory effects experienced by two null test particles with vanishing initial relative velocity after the passage of the pulse.
This exact radiative solution offers a simple framework to witness nonlinear consequences of the scalar-tensor mixing in higher-order scalar-tensor theories.
Observing gravitational waves with solar system astrometry
Authors: Mentasti G. , Contaldi C.R. 
Published: May 2024

AbstractThe subtle influence of gravitational waves on the apparent positioning of celestial bodies offers novel observational windows [1,2,3,4]. We calculate the expected astrometric signal induced by an isotropic Stochastic Gravitational Wave Background (SGWB) in the short distance limit. Our focus is on the resultant proper motion of Solar System objects, a signal on the same time scales addressed by Pulsar Timing Arrays (PTA). We derive the corresponding astrometric deflection patterns, finding that they manifest as distinctive dipole and quadrupole correlations or, in some cases, may not be present. Our analysis encompasses both Einsteinian and non-Einsteinian polarisations. We estimate the upper limits for the amplitude of SGWBs that could be obtained by tracking the proper motions of large numbers of solar system objects such as asteroids. We find that for SGWBs with negative spectral indices, such as that generated by Super Massive Black Hole Binaries (SMBHB), the constraints from these observations could rival those from PTAs. With the Gaia satellite and the Vera C. Rubin Observatory poised to track an extensive sample of asteroids — ranging from 𝒪(105) to 𝒪(106), we highlight the significant future potential for similar surveys to contribute to our understanding of the SGWB.
Exploring antisymmetric tensor effects on black hole shadows and quasinormal frequencies
Authors: Araújo Filho A.A. , Reis J.A.A.S. , Hassanabadi H. 
Published: May 2024

Abstract
This study explores the impact of antisymmetric tensor effects on spherically symmetric black holes, investigating photon spheres, shadows, emission rate and quasinormal frequencies in relation to a parameter which triggers the Lorentz symmetry breaking. We examine these configurations without and with the presence of a cosmological constant. In the first scenario, the Lorentz violation parameter, denoted as λ, plays a pivotal role in reducing both the photon sphere and the shadow radius, while also leading to a damping effect on quasinormal frequencies. Conversely, in the second scenario, as the values of the cosmological constant (Λ) increase, we observe an expansion in the shadow radius. Also, we provide the constraints of the shadows based on the analysis observational data obtained from the Event Horizon Telescope (EHT) focusing on Sagittarius A*
shadow images. Additionally, with the increasing Λ, the associated gravitational wave frequencies exhibit reduced damping modes.
Measurement-free mediated semi-quantum key distribution protocol based on single-particle states
Authors: Zhou Shun , Xie Qi-Ming , Zhou Nan-Run 
Published: May 2024

Abstract
A novel measurement-free mediated semi-quantum key distribution (MSQKD) protocol is proposed based on single-particle states. It enables two classical users to establish a secret key with the assistance of a third party. This protocol simplifies the third party’s role to solely generating qubits in X-basis and conducting Bell measurements. A distinctive feature of this protocol is the efficient grouping and reordering of qubits by the classical users with a minimum of three delay lines. Security analyses demonstrate that the protocol can withstand various attack strategies, including collective attack, measurement attack, fake state attack, and modification attack. The noise tolerance is given by deriving a lower bound of the protocol’s key rate in the asymptotic scenario. Simulations on the IBM Quantum Experience platform are conducted to illustrate the feasibility of this protocol. Compared with existing MSQKD protocols, the proposed protocol consumes fewer quantum resources and achieves a qubit efficiency of 1/8.
Topological superconductors with spin-triplet pairings and Majorana Fermi arcs
Authors: Huang 黄 Shi 石 , Luo 罗 Xi 熙 
Published: May 2024

Abstract
We construct a three-dimensional topological superconductor Bogoliubov–de Gennes (BdG) Hamiltonian with the normal state being a three-dimensional topological insulator. By introducing inter-orbital spin-triplet pairings term Δ
3, there are topological Majorana nodes in the bulk and they are connected by Majorana Fermi arcs on the surface, similar to the case of Weyl semimetal. Furthermore, by adding an inversion-breaking term to the normal state, momentum-independent pairing terms with different parities can coexist in the BdG Hamiltonian, which creates more Majorana modes similar to Andreev bound states and a richer phase diagram.
An integrable generalization of the Fokas–Lenells equation: Darboux transformation, reduction and explicit soliton solutions
Authors: Wei 魏 Jiao 姣 , Geng 耿 Xianguo 献国 , Wang 王 Xin 鑫 
Published: May 2024

Abstract
Under investigation is an integrable generalization of the Fokas–Lenells equation, which can be derived from the negative power flow of a 2 × 2 matrix spectral problem with three potentials. Based on the gauge transformation of the matrix spectral problem, one kind of Darboux transformation with multi-parameters for the three-component coupled Fokas–Lenells system is constructed. As a reduction, the N-fold Darboux transformation for the generalized Fokas–Lenells equation is obtained, from which the N-soliton solution in a compact Vandermonde-like determinant form is given. Particularly, the explicit one- and two-soliton solutions are presented and their dynamical behaviors are shown graphically.
Design and control of jumping microrobots with torque reversal latches
Authors: Skowronski Nolan , Malek Pour Mohammadamin , Singh Shashwat , Longo Sarah J , St Pierre Ryan 
Published: May 2024

Abstract
Jumping microrobots and insects power their impressive leaps through systems of springs and latches. Using springs and latches, rather than motors or muscles, as actuators to power jumps imposes new challenges on controlling the performance of the jump. In this paper, we show how tuning the motor and spring relative to one another in a torque reversal latch can lead to an ability to control jump output, producing either tuneable (variable) or stereotyped jumps. We develop and utilize a simple mathematical model to explore the underlying design, dynamics, and control of a torque reversal mechanism, provides the opportunity to achieve different outcomes through the interaction between geometry, spring properties, and motor voltage. We relate system design and control parameters to performance to guide the design of torque reversal mechanisms for either variable or stereotyped jump performance. We then build a small (356 mg) microrobot and characterize the constituent components (e.g. motor and spring). Through tuning the actuator and spring relative to the geometry of the torque reversal mechanism, we demonstrate that we can achieve jumping microrobots that both jump with different take-off velocities given the actuator input (variable jumping), and those that jump with nearly the same take-off velocity with actuator input (stereotyped jumping). The coupling between spring characteristics and geometry in this system has benefits for resource-limited microrobots, and our work highlights design combinations that have synergistic impacts on output, compared to others that constrain it. This work will guide new design principles for enabling control in resource-limited jumping microrobots.
3D-printed porous tantalum artificial bone scaffolds: fabrication, properties, and applications
Authors: Yu Haiyu , Xu Minghao , Duan Qida , Li Yada , Liu Yuchen , Song Liqun , Cheng Liangliang , Ying Jiawei , Zhao Dewei 
Published: May 2024

Abstract
Porous tantalum scaffolds offer a high degree of biocompatibility and have a low friction coefficient. In addition, their biomimetic porous structure and mechanical properties, which closely resemble human bone tissue, make them a popular area of research in the field of bone defect repair. With the rapid advancement of additive manufacturing, 3D-printed porous tantalum scaffolds have increasingly emerged in recent years, offering exceptional design flexibility, as well as facilitating the fabrication of intricate geometries and complex pore structures that similar to human anatomy. This review provides a comprehensive description of the techniques, procedures, and specific parameters involved in the 3D printing of porous tantalum scaffolds. Concurrently, the review provides a summary of the mechanical properties, osteogenesis and antibacterial properties of porous tantalum scaffolds. The use of surface modification techniques and the drug carriers can enhance the characteristics of porous tantalum scaffolds. Accordingly, the review discusses the application of these porous tantalum materials in clinical settings. Multiple studies have demonstrated that 3D-printed porous tantalum scaffolds exhibit exceptional corrosion resistance, biocompatibility, and osteogenic properties. As a result, they are considered highly suitable biomaterials for repairing bone defects. Despite the rapid development of 3D-printed porous tantalum scaffolds, they still encounter challenges and issues when used as bone defect implants in clinical applications. Ultimately, a concise overview of the primary challenges faced by 3D-printed porous tantalum scaffolds is offered, and corresponding insights to promote further exploration and advancement in this domain are presented.
Organoid bioinks: construction and application
Authors: Wang Fuxiao , Song Peiran , Wang Jian , Wang Sicheng , Liu Yuanyuan , Bai Long , Su Jiacan 
Published: May 2024

Abstract
Organoids have emerged as crucial platforms in tissue engineering and regenerative medicine but confront challenges in faithfully mimicking native tissue structures and functions. Bioprinting technologies offer a significant advancement, especially when combined with organoid bioinks-engineered formulations designed to encapsulate both the architectural and functional elements of specific tissues. This review provides a rigorous, focused examination of the evolution and impact of organoid bioprinting. It emphasizes the role of organoid bioinks that integrate key cellular components and microenvironmental cues to more accurately replicate native tissue complexity. Furthermore, this review anticipates a transformative landscape invigorated by the integration of artificial intelligence with bioprinting techniques. Such fusion promises to refine organoid bioink formulations and optimize bioprinting parameters, thus catalyzing unprecedented advancements in regenerative medicine. In summary, this review accentuates the pivotal role and transformative potential of organoid bioinks and bioprinting in advancing regenerative therapies, deepening our understanding of organ development, and clarifying disease mechanisms.
Functionally graded hydrogels with opposing biochemical cues for osteochondral tissue engineering
Authors: Mahajan Aman , Zaidi Zahra Sifat , Shukla Amit , Saxena Rakshita , Katti Dhirendra S 
Published: May 2024

Abstract
Osteochondral tissue (OC) repair remains a significant challenge in the field of musculoskeletal tissue engineering. OC tissue displays a gradient structure characterized by variations in both cell types and extracellular matrix components, from cartilage to the subchondral bone. These functional gradients observed in the native tissue have been replicated to engineer OC tissue in vitro. While diverse fabrication methods have been employed to create these microenvironments, emulating the natural gradients and effective regeneration of the tissue continues to present a significant challenge. In this study, we present the design and development of CMC-silk interpenetrating (IPN) hydrogel with opposing dual biochemical gradients similar to native tissue with the aim to regenerate the complete OC unit. The gradients of biochemical cues were generated using an in-house-built extrusion system. Firstly, we fabricated a hydrogel that exhibits a smooth transition of sulfated carboxymethyl cellulose (sCMC) and TGF-β1 (SCT gradient hydrogel) from the upper to the lower region of the IPN hydrogel to regenerate the cartilage layer. Secondly, a hydrogel with a hydroxyapatite (HAp) gradient (HAp gradient hydrogel) from the lower to the upper region was fabricated to facilitate the regeneration of the subchondral bone layer. Subsequently, we developed a dual biochemical gradient hydrogel with a smooth transition of sCMC + TGF-β1 and HAp gradients in opposing directions, along with a blend of both biochemical cues in the middle. The results showed that the dual biochemical gradient hydrogels with biochemical cues corresponding to the three zones (i.e. cartilage, interface and bone) of the OC tissue led to differentiation of bone-marrow-derived mesenchymal stem cells to zone-specific lineages, thereby demonstrating their efficacy in directing the fate of progenitor cells. In summary, our study provided a simple and innovative method for incorporating gradients of biochemical cues into hydrogels. The gradients of biochemical cues spatially guided the differentiation of stem cells and facilitated tissue growth, which would eventually lead to the regeneration of the entire OC tissue with a smooth transition from cartilage (soft) to bone (hard) tissues. This promising approach is translatable and has the potential to generate numerous biochemical and biophysical gradients for regeneration of other interface tissues, such as tendon-to-muscle and ligament-to-bone.
Maximization of uricase production in a column bioreactor through response surface methodology-based optimization
Authors: Taghizadeh Mohammad Hossein , Khajeh Khosro , Nasirpour Niloofar , Mousavi Seyyed Mohammad 
Published: May 2024

Abstract
Uricase (EC 1.7.3.3) is an oxidoreductase enzyme that is widely exploited for diagnostic and treatment purposes in medicine. This study focuses on producing recombinant uricase from E. coli BL21 in a bubble column bioreactor (BCB) and finding the optimal conditions for maximum uricase activity. The three most effective variables on uricase activity were selected through the Plackett–Burman design from eight different variables and were further optimized by the central composite design of the response surface methodology (RSM). The selected variables included the inoculum size (%v/v), isopropyl β-d-1-thiogalactopyranoside (IPTG) concentration (mM) and the initial pH of the culture medium. The activity of uricase, the final optical density at 600 nm wavelength (OD600) and the final pH were considered as the responses of this optimization and were modeled. As a result, activity of 5.84 U·ml−1 and a final OD600 of 3.42 were obtained at optimum conditions of 3% v/v inoculum size, an IPTG concentration of 0.54 mM and a pH of 6.0. By purifying the obtained enzyme using a Ni-NTA agarose affinity chromatography column, 165 ± 1.5 mg uricase was obtained from a 600 ml cell culture. The results of this study show that BCBs can be a highly effective option for large-scale uricase production.
Preparation method and applicability evaluation of 3D printing alumina ceramic artificial coarse aggregate
Authors: Zhang Yake , Li Xi , Hu Kaikai , Qian Guoping , Gong Xiangbing , Yu Huanan 
Published: May 2024

Abstract
The particle size and morphology of crushed stones impact their macroscopic mechanical and physical properties, which has become a hot topic in the study of road and geotechnical engineering. However, some reported studies fail to control the particle morphology as the only independent variable. This paper presented a new method to print artificial aggregates based on 3D printing technology of particles. The applicability of the new method was verified with uniaxial compression and dynamic modulus tests of asphalt mixtures formed by the printing aggregates. Results showed that the printing aggregates earned similar physical properties to real coarse when sintered at 1400 °C with alumina ceramic powder and CuO: TiO2 a 1:2 additive in mass. Besides, the gross volume density, compressive strength, and shrinkage of the printing aggregates show a similar trend of increasing and then decreasing with the increase of additives. The optimal mass percentage of additives was obtained to be 5%. Mechanical tests indicated that the mechanical indexes of the asphalt mixtures formed with the two types of coarse aggregates were similar, while the results of the specimens formed with artificial coarse aggregates showed less dispersion. The stability of test results was significantly improved for different asphalt mixture specimens prepared with 3D printed coarse aggregate. This provides a basic method for further research on the multi-scale properties of particle material.