Negative / Null Result ReportOpen accessPhysics
Pei-Lun He, Zhao-Han Zhang, Karen Z. Hatsagortsyan et al. · 2024 · arXiv
The spin polarization of photoelectrons induced by an intense linearly polarized laser field is investigated using numerical solutions of the time-dependent Schrödinger equation in companion with our analytic treatment via the spin-resolved strong-field approximation and classical trajectory Monte Carlo simulations. We demonstrate that, even though the total polarization vanishes upon averaging over the photoelectron momentum, momentum-resolved spin polarization is significant, typically exhibiting a vortex structure relative to the laser polarization axis. The polarization arises from the tra
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Z. Q. Sun, F. Y. Wang · 2018 · arXiv
Recent studies have indicated that an anisotropic cosmic expansion may exist. In this paper, we use three datasets of type Ia supernovae (SNe Ia) to probe the isotropy of cosmic acceleration. For the Union2.1 dataset, the direction and magnitude of the dipole are $(l=309.3^{\circ} {}^{+ 15.5^{\circ}}_{-15.7^{\circ}} ,\ b = -8.9^{\circ} {}^{ + 11.2^{\circ}}_{-9.8^{\circ}} ),\ A=(1.46 \pm 0.56) \times 10^{-3}$. For the Constitution dataset, the results are $(l=67.0^{\circ}{}^{+ 66.5^{\circ}}_{-66.2^{\circ}},\ b=-0.6^{\circ}{}^{+ 25.2^{\circ}}_{-26.3^{\circ}}),\ A=(4.4 \pm 5.0) \times 10^{-4}$. F
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José F. Fontanari, Paulo R. A. Campos · 2025 · arXiv
Synchronized short-term activity cycles are a prominent feature in the nests of certain ant species, but their functional significance remains controversial. This study investigates whether synchronization enhances spatial accessibility within ant nests, a factor critical for efficient task performance and colony fitness. We use the mobile oscillator model, a computational framework that simulates ant movement and synchronous activity, to examine the effect of synchronization on the spatial distribution of inactive ants, which act as obstacles to the movement of active ants. Our analysis revea
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A. Boughena, S. Benalia, O. Cheref et al. · 2021 · arXiv
Topological nontrivial nature are the latest phases to be discovered in condensed matter physics with insulating bulk band gaps and topologically protected metallic surface states; they are one of the current hot topics because of their unique properties and potential applications. In this paper, we have highlighted a first-principles study of the structural stability and electronic behavior of the Na${}_{2}$AgX (X= As, Sb and Bi) full Heusler compounds, using the Full-Potential Linear Muffin-Tin Orbital (FP-LMTO) method. We have originated that the Hg${}_{2}$CuTi structure is appropriate in a
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Narayan Khadka, Michal Zajaček, Swayamtrupta Panda et al. · 2022 · arXiv
We use observations of 66 reverberation-measured \Mgii\ quasars (QSOs) in the redshift range $0.36 \leq z \leq 1.686$ -- a subset of the 78 QSOs we previously studied that also have \rfe\ (flux ratio parameter of UV \Feii\ to \Mgii\ that is used as an accretion-rate proxy) measurements -- to simultaneously constrain cosmological model parameters and QSO 2-parameter and 3-parameter radius-luminosity ($R-L$) relation parameters in six different cosmological models. We find that these QSO $R-L$ relation parameters are independent of the assumed cosmological model and so these QSOs are standardiza
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Rabiah A. Rahmat, Melissa A. Humphries, Jeremy J. Austin et al. · 2020 · arXiv
Heat alters colour and crystallinity of teeth by destruction of the organic content and inducing hydroxyapatite crystal growth. The colour and crystallite changes can be quantified using spectrophotometric and x-ray diffraction analyses, however these analyses are not commonly used in combination to evaluate burned dental remains. In this study, thirty-nine teeth were incinerated at 300-1000$^\circ$C for 15 and 30 minutes and then measured using a spectrophotometer and an x-ray diffractometer. Response variables used were lightness, L$^\ast$, and chromaticity a$^\ast$ and b$^\ast$ and luminanc
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E. Forgacs-Dajka · 2006 · arXiv
We present detailed numerical calculations of the fast solar tachocline based on the assumption that the dynamo field dominates over the dynamics of the tachocline. In the present paper of the series, we focus on three shortfalls of the earlier models. First, instead of the simple oscillating dipole poloidal field we study the more general magnetic field structures reminiscent of the butterfly diagram. The migrating field is prescribed as the observed axisymmetric radial magnetic field Stenflo (1988, 1994). Our results are in good agreement with our analitical estimate and our previous works i
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M. Joyce, M. Montuori, F. Sylos Labini · 1999 · arXiv
We report our analysis of the properties of galaxy clustering for a new redshift sample of galaxies, the CfA2-South catalog, using statistical methods which do not rely on the assumption of homogeneity. We find that, up to ~ 20 Mpc/h, which is the largest scale to which correlation properties can be reliably inferred, the galaxy clustering is scale-invariant and characterized by a fractal dimension D=1.9 \pm 0.1. Further there is no statistical evidence for homogeneity at any of the larger scales (up to ~150 Mpc/h) probed more weakly by the catalog. These results means that characteristic ``co
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Vadim V. Bobylev, Maxim Yu. Khovritchev · 2006 · arXiv
Based on the Ogorodnikov-Milne model, we analyze the proper motions of Tycho-2 and UCAC2 stars. We have established that the model component that describes the rotation of all stars under consideration around the Galactic y axis differs significantly from zero at various magnitudes. We interpret this rotation found using the most distant stars as a residual rotation of the ICRS/Tycho-2 system relative to the inertial reference frame. For the most distant ($d\approx900$ pc) Tycho-2 and UCAC2 stars, the mean rotation around the Galactic y axis has been found to be $M_{13}=-0.37\pm0.04$ mas yr$^{
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L. K. Alexander, N. Buettgen, R. Nath et al. · 2006 · arXiv
We report 7Li NMR, magnetic susceptibility, and heat capacity measurements on the triangular lattice Heisenberg antiferromagnet compound LiCrO2. We find that in contrast to NaCrO2, magnetic properties of LiCrO2 have a more pronounced three dimensional character with sharp anomalies in the temperature variation of the 7Li NMR intensity and the NMR spin-lattice relaxation rate 1/T1. From heat capacity measurements we find that the total entropy related to the magnetic transition is in agreement with expectations. However, we find a significant contribution to the magnetic entropy in the range fr
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K. Pradeesh, C. J. Oton, V. K. Agotiya et al. · 2007 · arXiv
A new class of Erbium doped glasses with compositions xNa2O - (60-x)PbCl2 - 40P2O5 (x=0, 10, 20 and 30) were fabricated and characterized for optical properties. Absorption spectra were analyzed for important Judd-Ofelt parameters from the integrated intensities of various Er3+ glass absorption bands. Photoluminescence (PL) and its decay behavior studies were carried out for the transition 4I13/2 -> 4I15/2. A systematic correlation between the Judd-Ofelt parameter {omega}2 and the covalent nature of the glass matrix was observed, due to increased role of bridging oxygens in the glass network.
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Dongsu Ryu, Jongsoo Kim, Seung Soo Hong et al. · 2003 · arXiv
The Parker instability, which has been considered as a process governing the structure of the interstellar medium, is induced by the buoyancy of magnetic field and cosmic rays. In previous studies, while the magnetic field has been fully incorporated in the context of isothermal magnetohydrodynamics, cosmic rays have been normally treated with the simplifying assumption of infinite diffusion along magnetic field lines but no diffusion across them. The cosmic ray diffusion is, however, finite. In this work, we take into account fully the diffusion process of cosmic rays in a linear stability an
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Zahra Talebi Esfahani, Alireza Saffarzadeh, Ahmad Akhound et al. · 2020 · arXiv
The adsorption effects of small molecules (H$_{2}$O, CO, NH$_{3}$, NO$_{2}$) and large molecules (Tetracyanoquinodimethane (TCNQ) and Tetrafluoro-tetracyanoquinodimethane (F4TCNQ)) on electronic and magnetic properties of two triangular graphene antidot lattices (GALs), $[10,3,6]_{RTA}$ and $[10, 5]_{ETA}$, are investigated by means of first-principles calculations. We find that CO, NO$_{2}$, TCNQ, and F4TCNQ molecules are chemisorbed by both antidots, whereas NH$_{3}$ is physisorbed (chemisorbed) by $[10, 5]_{ETA}$ ($[10,3,6]_{RTA}$) structure. H$_{2}$O, CO, NH$_{3}$ molecules reveal no signi
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James D. Boyd, Martha E. Grady · 2020 · arXiv
We investigate laser-induced acoustic wave propagation through smooth and roughened titanium-coated glass substrates. Acoustic waves are generated in a controlled manner via the laser spallation technique. Surface displacements are measured during stress wave loading by alignment of a Michelson-type interferometer. A reflective coverslip panel facilitates capture of surface displacements during loading of as-received smooth and roughened specimens. Through interferometric experiments we extract the substrate stress profile at each laser fluence (energy per area). The shape and amplitude of the
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Pooja C. Sindhuraj, José M. Caridad, Corné Koks et al. · 2025 · arXiv
Hexagonal boron nitride (hBN), a two-dimensional (2D) material, garners interest for hosting bright quantum emitters at room temperature. A great variety of fabrication processes have been proposed with various yields of quantum emitters. In this work, we study the influence of several parameters, such as irradiation energy, annealing environment, and the type of hBN, on the emitter density in hBN. Our results show (i) high emitter density with oxygen irradiation at 204 eV, (ii) post-annealing in carbon-rich atmospheres significantly increases emitter density, reinforcing carbon's potential ro
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Chong Yang Du, André Guerra, Adam McElligott et al. · 2023 · arXiv
Reversible addition-fragmentation chain-transfer polymerization with a switchable chain-transfer agent was employed to synthesize amphiphilic block copolymers poly(styrene-b-vinylpyrrolidone) and poly(pentafluorostyrene-b-vinylpyrrolidone) at 10 wt.% hydrophobic content as kinetic hydrate inhibitors for methane hydrates. The dynamic viscosity of methane hydrate slurries was measured in a high-pressure rheometer up to 15 MPag. At 700 ppm of additives in aqueous media, the relative time for slurries to grow to 200 mPa s was 2.2-2.4 times longer than water reference values for the block copolymer
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Linda Qerimi, Sarah Malone, Eva Rexigel et al. · 2025 · arXiv
Visual-graphical qubit representations offer a means to introduce abstract quantum concepts - such as quantum state, superposition, or measurement - in an accessible manner, particularly for learners with low prior knowledge. Building on a previous expert rating of mechanisms of qubit representations, this study compared two representations - Bloch sphere and Quantum Bead - in terms of learning outcomes, task performance, cognitive load, and mid-term retention. The study was conducted with N=149 school students. The study assessed conceptual understanding, application-oriented task performance
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A. Mainzer, J. Bauer, R. M. Cutri et al. · 2014 · arXiv
NASA's Wide-field Infrared Survey Explorer (WISE) spacecraft has been brought out of hibernation and has resumed surveying the sky at 3.4 and 4.6 um. The scientific objectives of the NEOWISE reactivation mission are to detect, track, and characterize near-Earth asteroids and comets. The search for minor planets resumed on December 23, 2013, and the first new near-Earth object (NEO) was discovered six days later. As an infrared survey, NEOWISE detects asteroids based on their thermal emission and is equally sensitive to high and low albedo objects; consequently, NEOWISE-discovered NEOs tend to
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Zhangkai Cao, Shuning Tan, Ji Liu et al. · 2025 · arXiv
Motivated by significant discrepancies between experimental observations of electron-doped cuprates and numerical results of the Hubbard model, we investigate the role of nearest-neighbor (NN) electron interactions $V$ by studying the $t-U-V$ model on square lattices. Upon doping $δ$= 0.153, by using constrained path quantum Monte Carlo (CPQMC) method, we find that NN electron attraction $V$ can notably drive an exotic $p$-wave spin-triplet pairing, while the NN electron repulsion $V$ will suppress the $d_{x^2-y^2}$-wave ($d$-wave) pairing and triggers the $d_{xy}$-wave pairing. Especially in
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Steven Soriano, Rodolfo Ostilla-Monico · 2024 · arXiv
The interaction between a vortex and an impacting body which is oriented normally to it is complex due to the interaction of inviscid and viscous three-dimensional mechanisms. To model this process, direct numerical simulations of a thin cylinder intersecting a columnar vortex oriented normally to it are conducted. By varying the impact parameter and the Reynolds number, the two regimes of interaction mentioned in the literature are distinguished: the weak and strong vortex regimes. Low impact parameters, representing strong vortices, led to ejection and interaction of secondary vorticity from
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M. Akbari-Moghanjoughi · 2012 · arXiv
Using the quantum magnetohydrodynamics (QMHD) model, linear dispersion of magnetosonic waves are studied in a quasineutral quantum electron-ion plasma in two distinct regimes of nonrelativistic and relativistic degeneracies considering also the plasma composition effect. It is shown that the paramagnetic spin effects of the degenerated electrons plays a key role in dynamics of magnetosonic waves. The linear wave-speed is found to have minimum value at some degeneracy parameter in such plasmas. This is due to delicate interplay between relativistic degeneracy and the Pauli spin-magnetization. I
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Leonard Göke, Mario Kendziorski, Claudia Kemfert et al. · 2021 · arXiv
The current governance process to plan the German energy system omits two options to substitute grid expansion: First, placing renewables closer to demand instead of where site conditions are best. Second, utilizing storage instead of additional transmission infrastructure to prevent grid congestion. In the paper, we apply a comprehensive capacity expansion model based on the AnyMOD modelling framework to compare the status quo to alternative planning approaches for a fully renewable energy system. To represent spatiality and fluctuations of renewables, the German electricity sector is modelle
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Ludovic Huguet, Victor Lherm, Renaud Deguen et al. · 2025 · arXiv
Turbulent thermals emerge in a wide variety of geophysical and industrial flows, such as atmospheric cumulus convection and pollutant dispersal in oceans and lakes. When a buoyant fluid mass rises, or sinks, heat and mass transfers occur by the engulfment of the fresh surrounding fluid inside the thermal - a process that spans over multiple scales from macroscopic entrainment of ambient fluid to microscopic diffusive processes. Turbulent thermals are typically investigated through their integral properties (radius, depth, entrainment rate). However, mixing processes depend on the internal dist
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N. Nardetto, A. Fokin, P. Fouqué et al. · 2011 · arXiv
Context. Recent observations of LMC Cepheids bring new constraints on the slope of the period-projection factor relation (hereafter Pp relation) that is currently used in the Baade-Wesselink (hereafter BW) method of distance determination. The discrepancy between observations and theoretical analysis is particularly significant for short period Cepheids Aims. We investigate three physical effects that might possibly explain this discrepancy: (1) the spectroscopic S/N that is systematically lower for LMC Cepheids (around 10) compared to Galactic ones (up to 300), (2) the impact of the metallici
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N. D. Padilla, D. G. Lambas · 2003 · arXiv
We analyse the correlation function of mock galaxy clusters in redshift space. We constructed several mock catalogues designed to mimic the selection biases inherent in a variety of observational surveys. We explore different effects that contribute to the distortion of the clustering pattern; the pairwise velocity distribution of galaxy systems, coherent bulk motions, redshift errors and systematics in cluster identification. Our tests show that the redshift-space clustering pattern of galaxy systems is highly influenced by effects associated with the identification procedure from two dimensi
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Angus Hawkey, Aditya Dash, Xabier Rodríguez-Martínez et al. · 2025 · arXiv
Semiconducting single-walled carbon nanotubes (SWCNTs) are a promising thermoelectric material with high power factors after chemical p- or n-doping. Understanding the impact of dopant counterions on charge transport and thermoelectric properties of nanotube networks is essential to further optimize doping methods and to develop better dopants. Here, we utilize ion-exchange doping to systematically vary the size of counterions in thin films of small and large diameter, polymer-sorted semiconducting SWCNTs with AuCl3 as the initial p-dopant and investigate the impact of ion size on conductivity
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Ozgur Akarsu, Suresh Kumar, Shivani Sharma et al. · 2019 · arXiv
We consider the simplest anisotropic generalization, as a correction, to the standard $Λ$CDM model, by replacing the spatially flat Robertson-Walker metric by the Bianchi type-I metric, which brings in a new term $Ω_{σ0}a^{-6}$ (mimicking the stiff fluid) in the average expansion rate $H(a)$ of the Universe. From Hubble and Pantheon data, relevant to the late Universe ($z\lesssim 2.4$), we obtain the constraint $Ω_{\sigma0}\lesssim10^{-3}$, in line with the model-independent constraints. When the baryonic acoustic oscillations and cosmic microwave background (CMB) data are included, the constr
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Sina Feldmann, Juliane Adrian, Maik Boltes · 2025 · arXiv
Impulse propagation in crowds is a phenomenon that is crucial for understanding collective dynamics, but has been scarcely addressed so far. Therefore, we have carried out experiments in which persons standing in a crowd are pushed forward in a controlled manner. Variations of experimental parameters include (i) the intensity of the push, (ii) the initial inter-person distance, (iii) the preparedness of participants and (iv) the crowd formation. Our analysis links the intensity of an impulse recorded by a pressure sensor with individual movements of participants based on head trajectories reco
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P. Hazarika, U. D. Goswami, V. R. Chitnis et al. · 2014 · arXiv
We have investigated some features of the density and arrival time distributions of Cherenkov photons in extensive air showers using the CORSIKA simulation package. The main thrust of this study is to see the effect of hadronic interaction models on the production pattern of Cherenkov photons with respect to distance from the shower core. Such studies are very important in ground based $γ$-ray astronomy for an effective rejection of huge cosmic ray background, where the atmospheric Cherenkov technique is being used extensively within the energy range of some hundred GeV to few TeV. We have fou
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Nicolas Abi Chebel, Olivier Masbernat, Frédéric Risso et al. · 2008 · arXiv
The present work investigates free damped oscillations of an oil drop in water after its release from a capillary tube. Both pure heptane drops and diluted crude oil drops are considered (in the second case the interface is covered by amphiphilic species, natural components of crude oil). Shadowgraph images of the drops are taken by means of a high speed camera and the drop contour is detected by image processing. The axisymmetric drop shape is then decomposed into spherical harmonics, which constitute the eigenmodes of oscillations predicted by the Rayleigh-Lamb theory. Time evolution of each
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