bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unconventional long range triplet proximity effect in planar YBa2Cu3O7/La0.7Sr0.3MnO3/YBa2Cu3O7 Josephson junctions
Authors: Sanchez-Manzano David , Mesoraca S , Cuellar F , Cabero M , Rodriguez-Corvillo S , Rouco V , Mompean F , Garcia-Hernandez M , Gonzalez-Calbet J M , Feuillet-Palma C , Bergeal N , Lesueur J , Leon C , Villegas Javier E , Santamaria J 
Published: April 2023

Abstract
The proximity effect between superconductors and ferromagnets may become long range due to the generation of triplet pairs. The recent finding of a long, one micron-range unconventional Josephson effect between YBa2Cu3O7 high Tc cuprates separated by a half metallic La0.7Sr0.3MnO3 manganite ferromagnet has uncovered a novel unconventional triplet proximity effect. In this paper, we examine the temperature dependence of the critical current in planar Josephson junctions. We find that the critical current—normal resistance product follows the predictions of traditional superconductor-normal metal-superconductor junctions, which implies that triplet pairs in a ferromagnet are transported in the diffusive limit similarly to singlet pairs in a normal metal. This result calls for theoretical studies of the new triplet Josephson effect and underlines its potential in future superconducting spintronics.
Probing the initial state of inflation: analytical structure of cosmological correlators
Authors: Ghosh Diptimoy , Harsh Singh Amartya , Ullah Farman 
Published: April 2023

Abstract
We study the analytic structure of in-in correlation functions in a deSitter background. The aim of this study is to probe the initial conditions for inflation through the features of correlation functions of the field fluctuations, and understand precisely how an in-in correlator responds to particles in the initial state. We emphasize that the choice of vacuua and the corresponding particle interpretation for these fluctuations is flexible, and we clarify the role of this choice at the level of calculations and their diagrammatic interpretation. We consider several possibilities aside from the standard Bunch Davies (BD) vacuum prescription for the initial state, and trace the change in pole structure as one begins adding excitations; starting from just a single particle, to highly excited states and special cases such as a coherent state. We also go beyond the pole structure of the bispectrum, and calculate the 4 point classical and quantum correlators.
We illustrate — with the example of coherent states — the subtleties in concluding a Bunch Davies initial state from the absence of physical poles in the bispectrum, which is interesting in light of some recent literature.
Initial states with a finite number of excitations are plagued with disconnected diagrams isolated in phase space, and we highlight their implications on the observation of these signals, and how the situation changes as one begins to excite more and more particles. We also comment about the implications of various initial conditions on the squeezed limit of the bispectrum.
These new pole structures are a direct consequence of mixing of positive and negative frequency modes which is a characteristic of curved spacetimes; in particular, we see in detail how particles in an initial state replicate mode mixing structures. This study aims to clarify the missing details that link quantum and classical initial conditions, and sharpen our understanding of in-in correlators in inflation.
Gravitational waves from current-carrying cosmic strings
Authors: Auclair Pierre , Blasi Simone , Brdar Vedran , Schmitz Kai 
Published: April 2023

Abstract
Cosmic strings are predicted by many Standard Model extensions involving the cosmological breaking of a symmetry with nontrivial first homotopy group and represent a potential source of primordial gravitational waves (GWs).
Present efforts to model the GW signal from cosmic strings are often based on minimal models, such as, e.g., the Nambu-Goto action that describes cosmic strings as exactly one-dimensional objects without any internal structure.

In order to arrive at more realistic predictions, it is therefore necessary to consider nonminimal models that make an attempt at accounting for the microscopic properties of cosmic strings.

With this goal in mind, we derive in this paper the GW spectrum emitted by current-carrying cosmic strings (CCCSs), which may form in a variety of cosmological scenarios.

Our analysis is based on a generalized version of the velocity-dependent one-scale (VOS) model, which, in addition to the mean velocity and correlation length of the string network, also describes the evolution of a chiral (light-like) current.

As we are able to show, the solutions of the VOS equations imply a temporarily growing fractional cosmic-string energy density, Ωcs.

This results in an enhanced GW signal across a broad frequency interval, whose boundaries are determined by the times of generation and decay of cosmic-string currents.

Our findings have important implications for GW experiments in the Hz to MHz band and motivate the construction of realistic particle physics models that give rise to large currents on cosmic strings.
Questions on calculation of primordial power spectrum with large spikes: the resonance model case
Authors: Inomata Keisuke , Braglia Matteo , Chen Xingang 
Published: April 2023

Abstract
Inflationary models predicting a scale-dependent large amplification of the density
perturbations have recently attracted a lot of attention because the amplified perturbations can
seed a sizable amount of primordial black holes (PBHs) and stochastic background of gravitational
waves (GWs). While the power spectra in these models are computed based on the linear equation of
motion, it is not obvious whether loop corrections are negligible when such a large amplification
occurs during inflation. In this paper, as a first step to discuss the loop corrections in such
models, we use the in-in formalism and calculate the one-loop scalar power spectrum numerically
and analytically in an illustrative model where the density perturbations are resonantly amplified
due to oscillatory features in the inflaton potential. Our calculation is technically new in that
the amplified perturbations are numerically taken into account in the in-in formalism for the
first time. In arriving at our analytical estimates, we highlight the role that the Wronskian
condition of perturbations, automatically satisfied in our model, plays in obtaining the correct
estimates. In addition, the analytical estimates show that the contribution originating from the
quantum nature of the perturbations in the loop can be dominant. We also discuss the necessary
conditions for subdominant loop corrections in this model. We find that, for the typical
parameter space leading to the 𝒪(107) amplification of the power spectrum required for
a sufficient PBH production, the one-loop power spectrum dominates over the tree-level one,
indicating the breakdown of the perturbation theory.
An extended laser cavity centered at 780 nm for high-resolution laser spectroscopy applications
Authors: Álvarez J , Pimienta J , Mercado E , Sarmiento R 
Published: April 2023

Abstract
Laser diodes (LDs) working in free mode present different types of effects such as shift and broadening of the spectral peak, determined by external factors such as temperature, electric current or mechanical vibrations, which are undesirable when required in applications such as high resolution laser spectroscopy, metrology or laser cooling. To reduce the width of the spectral emission peak of a laser, different configurations or optical setups are used, among which one of the most effective is to extend the optical resonator of the LD and use optical feedback, either with the help of a partially reflective mirror or with a diffraction grating. In this work, we present the design, construction, and characterization of a compact extended-cavity diode laser (ECDL) in Littrow configuration. The ECDL was machined on an aluminum block using computerized numerical control. It operates at a wavelength of 780.24 nm with a maximum output power of 35 mW. The results showed a spectral linewidth of 340 kHz using the self-heterodyne technique and a frequency stability of 0.47 MHz when the cavity was stabilized with an atomic reference.
Systematic studies on the nuclear parton distribution with photon and hadron productions in nuclear collisions at the LHC*
Authors: Li Xing-Long , Zhu Ya , Zhang Xiao-Ming , Zhou Dai-Cui 
Published: April 2023

Abstract
A systematic study on the impact of widely-used nuclear-modified parton distribution function (nPDF) parameterizations on the production of direct photons and charged hadrons is performed by employing a next-to-leading order Monte Carlo event generator JETPHOX in hadronic collisions at LHC energies. The nuclear modification factors of photon and charged hadron productions are studied in three types of collision systems, i.e., small (

and

), medium

, and large

, in a wide rapidity acceptance. The results illustrate that the direct photon production process is a sensitive probe to decipher the difference of the nPDF parameterization implementations, which provides new insights for the experimental measurements to refine the nuclear modifications of the parton distributions. To provide a benchmark for searching for quark gluon plasma in the upcoming small system measurements at LHC energies, we carry out detailed studies on the cold nuclear matter effect in

collisions. Our outcomes show that the cold nuclear matter effects are negligible for the charged hadron production in

collisions, which can be used as a baseline to subtract the initial state contribution.
Identifying Pauli blockade regimes in bilayer graphene double quantum dots
Authors: Mukherjee Ankan , Muralidharan Bhaskaran 
Published: April 2023

Abstract
Recent experimental observations of current blockades in 2D material quantum-dot platforms have opened new avenues for spin and valley-qubit processing. Motivated by experimental results, we construct a model capturing the delicate interplay of Coulomb interactions, inter-dot tunneling, Zeeman splittings, and intrinsic spin–orbit coupling in a double quantum dot (DQD) structure to simulate the Pauli blockades. Analyzing the relevant Fock-subspaces of the generalized Hamiltonian, coupled with the density matrix master equation technique for transport across the setup, we identify the generic class of blockade mechanisms. Most importantly, and contrary to what is widely recognized, we show that conducting and blocking states responsible for the Pauli-blockades are a result of the coupled effect of all degrees of freedom and cannot be explained using the spin or the valley pseudo-spin only. We then numerically predict the regimes where Pauli blockades might occur, and, to this end, we verify our model against actual experimental data and propose that our model can be used to generate data sets for different values of parameters with the ultimate goal of training on a machine learning algorithm. Our work provides an enabling platform for a predictable theory-aided experimental realization of single-shot readout of the spin and valley states on DQDs based on 2D-material platforms.
Insights to the fracture toughness, damage tolerance, electronic structure, and magnetic properties of carbides M2C (M = Fe, Cr)
Authors: Duan Junwen , Hou Tingping , Zhang Dong , Wu Kaiming 
Published: April 2023

Abstract
The fracture toughness, damage tolerance, electronic structure, and magnetic properties of M2C (M = Fe, Cr) carbides were analyzed using first-principles calculations. Calculations of formation energy and modulus of elasticity indicate that a Cr/Fe ratio of 1/3 is a critical threshold which triggers a significant increase in the corresponding stability and related mechanical properties. Cr atomic content enhances the crack resistance, while Cr has a significantly detrimental effect on damage resistance. The electronic properties demonstrated that the Cr atom content enhances the metallic, ionic and covalent bonding. Furthermore, the reduction in the coordination number of Fe atoms is the main reason for the reduction in the local magnetic moment of the low-spin Cr atoms, which is strongly supported by the electronic structure. These studies provide detailed insights into Cr-containing carbides, providing valuable theoretical and technological information for the knowledge-based design and prediction of the mechanical properties of chromium-containing iron-based materials.
Local field enhancement factor of spheroidal core–shell nanocomposites with passive and active dielectric cores
Authors: Hirpha Tolasa Tamasgen , Bergaga Garoma Dhaba , Ali Belayneh Mesfin , Shewamare Gebre Sisay 
Published: April 2023

Abstract
We studied the effects of depolarization factor (L), metal fraction (p), and dielectric function of host matrix (ε

h
) on the local field enhancement factor (LFEF) of spheroidal core–shell nanocomposites (NCs) with passive and active dielectric cores. Solving Laplace’s equations in the quasi-static limit, we obtained expressions of electric potentials for spheroidal core–shell NCs. Then, by introducing L and the Drude-Sommerfeld model into these expressions, we derived the equation of LFEF in the core of spheroidal core–shell NCs. The results show that whether L, p, and/or ε

h
vary or kept constant, LFEF of the spheroidal core–shell NCs possesses two sets of peaks with passive dielectric core, whereas only a set of peak is observed with active dielectric core. In NCs with passive dielectric core, an increase in any of these parameters resulted in a more pronounced LFEF peaks in the first set of resonances. With both passive and active dielectric cores, increasing L increases the peaks of LFEF of spheroidal core–shell NCs, whereas increasing p shows decreasing tendency on the peaks of LFEF of the same material with active dielectric core. Moreover, the highest peak of LFEF is obtained by increasing L than p or ε

h
indicating that change in the geometry of spheroidal core–shell NCs has the highest effect on the LFEF than the metal concentration and host dielectric function. With the same increase in ε

h
, intensities of LFEF of the spheroidal core–shell NCs decrease when the dielectric core is passive and increase when the dielectric core is active. Briefly, the number and intensities of peaks of LFEF of spheroidal core–shell NCs vary greatly when its core is made either passive or active dielectric. Furthermore, by changing parameters like L, p, and ε

h
, adjustable LFEF could be obtained and used for applications in optical sensing, nonlinear optics, and quantum optics.
Study of imitative micro pit morphology evaluation
Authors: Panmongkol Picha , Rojviriya Catleya , Phung-on Isaratat 
Published: April 2023

Abstract
This study examined the imitative micro pit formation of pitting corrosion on 304 stainless steel under electrochemical control in a 3.0% NaCl solution. Results demonstrated that the micro pits changed from a conical to a cap shape during growth, indicating that their evolution in shape and growth did not follow the same morphology over time. Additionally, the piecewise polynomial method was employed to compare real-time micro pit growth morphology evolution with current density, which was consistent with cross-sectional images of actual micro pits, enabling the separation of the pitting corrosion stages. Furthermore, 3D images obtained from SRXTM were similar to cross-sectional images of real micro pits, further validating the technique’s usefulness in studying micro pits.
Effect of holding time and Ti/B molar ratio on microstructure and mechanical properties of in-situ TiB2/Al composites fabricated by mixed salt reaction
Authors: Xie Hui , Cao Yuanbao 
Published: April 2023

Abstract
In this study, in situ TiB2/Al composites is fabricated by K2TiF6 and KBF4 systems. The effects of process parameters on the size, distribution and morphology of in situ TiB2 particles, as well as the microstructure and mechanical properties of the composite is analyzed. When the mixed salts is added at 750 °C, TiB2 particles are short rods. When the temperature is higher than 825 °C, TiB2 particles are cubic columns and hexagonal columns. When the reaction temperature is 825 °C, the grain refinement of the composite is most obviously. When the holding time is 80 min, TiB2 particles are uniformly distributed in the matrix and the size is less than 2 μm. The ultimate tensile strength, yield strength and elongation of the composite reach the maximum values of 230 MPa, 125 MPa and 9.5%. When the holding time is 110 min, TiB2 particles agglomerate at the grain boundary, and the mechanical properties of the composites decrease. When the Ti/B molar ratio is 1/1, in addition to forming TiB2 particles, large size hard brittle phase TiAl3 appear in the microstructure. When the Ti/B molar ratio is 1/2.2, the formation of hard brittle phase TiAl3 can be inhibited, TiB2 particles are uniformly distributed in the matrix and the grain refinement is most obviously. The ultimate tensile strength, yield strength and elongation of the composite reach the maximum values of 225 MPa, 110 MPa and 8.5%. When the Ti/B molar ratio is 1/3, the unreacted residual mixed salts appear in the microstructure of the composite, and the residual mixed salts impurities exist at the interface between TiB2 particles and the matrix, so reduce the mechanical properties of the composite.
Feasibility of using bio-enzyme as an admixture in reactive powder concrete
Authors: Raja MA , Judes Sujatha S 
Published: April 2023

Abstract
Utilizing bio-based elements as cement additives has a significant impact on the production of extremely durable and sustainable concrete composites. In the present research work, the effect of a bio-enzyme (Terrazyme) on the strength, durability, and microstructure of RPC was researched at various proportions of Terrazyme (TZ) as binder replacement (0, 0.5, 1, 1.5, 2, and 2.5%). The migration of water and transport properties of concrete are accessed through measurement of the water absorption and gas permeability. Results show that the use of TZ in RPC slightly reduced the compressive strength, and the reduction was more significant at high replacement levels when subjected to water curing. A significant reduction in the permeability of RPC with a relatively low permeability coefficient is obtained even at higher dosages of TZ in autoclaved RPC specimens with greater mechanical strength. In addition, greater chloride penetration with the prolongation of ages is obtained. The inclusion of TZ can not only enhance the waterproofing and penetration resistance of RPC but also achieve economic and ecological benefits.
The effect of variable labels on deep learning models trained to predict breast density
Authors: Squires Steven , Harkness Elaine F , Evans D Gareth , Astley Susan M 
Published: April 2023

Abstract

Purpose. High breast density is associated with reduced efficacy of mammographic screening and increased risk of developing breast cancer. Accurate and reliable automated density estimates can be used for direct risk prediction and passing density related information to further predictive models. Expert reader assessments of density show a strong relationship to cancer risk but also inter-reader variation. The effect of label variability on model performance is important when considering how to utilise automated methods for both research and clinical purposes. Methods. We utilise subsets of images with density labels from the same 13 readers and 12 reader pairs, and train a deep transfer learning model which is used to assess how label variability affects the mapping from representation to prediction. We then create two end-to-end models: one that is trained on averaged labels across the reader pairs and the second that is trained using individual reader scores, with a novel alteration to the objective function. The combination of these two end-to-end models allows us to investigate the effect of label variability on the model representation formed. Results. We show that the trained mappings from representations to labels are altered considerably by the variability of reader scores. Training on labels with distribution variation removed causes the Spearman rank correlation coefficients to rise from 0.751 ± 0.002 to either 0.815 ± 0.026 when averaging across readers or 0.844 ± 0.002 when averaging across images. However, when we train different models to investigate the representation effect we see little difference, with Spearman rank correlation coefficients of 0.846 ± 0.006 and 0.850 ± 0.006 showing no statistically significant difference in the quality of the model representation with regard to density prediction. Conclusions. We show that the mapping between representation and mammographic density prediction is significantly affected by label variability. However, the effect of the label variability on the model representation is limited.
Nanoparticles reinforced joints produced using friction stir welding: a review
Authors: Singh Tanvir 
Published: April 2023

Abstract
Fusion welding processes do not find attention due to their restriction to use for certain grades of materials and alloys. Friction Stir welding (FSW) or the solid-state joining process has proven to be a more efficient process for the welding of metal-matrix reinforced composite butt joints by employing various combinations of reinforcement particles and base matrices compared to the fusion welding process. Due to the solid-state nature of the FSW process, no melting of base material would occur which leads to no toxic fumes, low energy consumption, environmentally friendly, and ease of operation that makes FSW a more versatile welding process for aerospace, automobile, and transportation industries. However, the challenges in joining metal matrix reinforced composites remain even with a substantial advancement in the process made during current years. This review article outlines a brief overview of the state of art of metal matrix reinforced welds joined using FSW. More emphasis with critical evaluation has been done on the (a) macrostructural and microstructural characteristics of a metal matrix reinforced welds which merely depend on the plasticized material flow and reinforcement particles behavior and its difficulty for uniform distribution of reinforcement particles in the weld zone based on the combination of reinforcement particles and the metal matrix materials, (b) assessment of mechanical properties of the metal matrix reinforced welds those are directly interdependent on the selection of process parameters by which the grain refinement and their reinforcement particles distribution depend that leads to changes in such properties, and (c) fracture and wear properties of the metal matrix reinforced welds which again depends on the reinforcement particles and the metal matrix materials combination. The conclusions of this review are ended up with recommendations for the directions for future research.