bluuebunny/crossref_metadata_2025 huggingface dataset:
Local Rotational Jamming and Multi-Stage Hyperuniformities in an Active Spinner System
Authors: Liu 刘 Rui 锐 , Gong 巩 Jianxiao 建晓 , Yang 杨 Mingcheng 明成 , Chen 陈 Ke 科
Published: November 2023

An active system consisting of many self-spinning dimers is simulated, and a distinct local rotational jamming transition is observed as the density increases. In the low density regime, the system stays in an absorbing state, in which each dimer rotates independently subject to the applied torque; while in the high density regime, a fraction of the dimers become rotationally jammed into local clusters, and the system exhibits microphase-separation like two-phase morphologies. For high enough densities, the system becomes completely jammed in both rotational and translational degrees of freedom. Such a simple system is found to exhibit rich and multiscale disordered hyperuniformities among the above phases: the absorbing state shows a critical hyperuniformity of the strongest class and subcritically preserves the vanishing density fluctuation scaling up to some length scale; the locally jammed state shows a two-phase hyperuniformity conversely beyond some length scale with respect to the phase cluster sizes; the totally jammed state appears to be a monomer crystal, but intrinsically loses large-scale hyperuniformity. These results are inspiring for designing novel phase-separation and disordered hyperuniform systems through dynamical organization.
EMF revisited
Authors: Davis Art
Published: November 2023

This paper was inspired by a recent publication by Redžíc (2018 Eur. J. Phys.
39 025205) which threw into bold relief the differences between the way Maxwell viewed the current and the way Lorentz visualized it. We make the assumption that for a circuit of laboratory dimensions current (and charge perturbation effects in general) can be assumed to propagate instantaneously around the loop. Our second fundamental assumption is the commonly accepted one that
E
is the force per unit charge on a stationary charge. We use these facts to make the usual definition of electromotive force more rigorous and to derive the Lorentz force formula.
Solving differential equations with deep learning: a beginner’s guide
Authors: Navarro Luis Medrano , Martin-Moreno Luis , Rodrigo Sergio G
Published: November 2023

The research in artificial intelligence methods with potential applications in science has become an essential task in the scientific community in recent years. Physics-informed neural networks (PINNs) is one of these methods and represents a contemporary technique based on neural network fundamentals to solve differential equations. These networks can potentially improve or complement classical numerical methods in computational physics, making them an exciting area of study. In this paper, we introduce PINNs at an elementary level, mainly oriented to physics education, making them suitable for educational purposes at both undergraduate and graduate levels. PINNs can be used to create virtual simulations and educational tools that aid in understating complex physical concepts and processes involving differential equations. By combining the power of neural networks with physics principles, PINNs can provide an interactive and engaging learning experience that can improve students’ understanding and retention of physics concepts in higher education.
High throughput microfluidic drug screening system for corneal epithelial wound healing
Authors: Lee Rina , Kim Hongbin , Kim Hoon , Lee Jinho , Cho Kyong Jin , Kim Jeongyun
Published: November 2023

In this study, we developed a microfluidic in vitro wound healing model to overcome the existing limitations of traditional experimental methods in quantifying cell migration. We manufactured a microfluidic system equipped with a gradient concentration generator to control the reagent density and with microvalves so the wound masking pattern could be automatically controlled by a programmable Arduino board. A wound healing experiment of human corneal epithelial cells (HCE-T cells) using eight different concentrations of ursolic acid with eight replicates was conducted simultaneously using our microfluidic system. A microfluidic in vitro wound healing model using HCE-T cells involving a programmable Arduino board for automatic process control was established to provide a well-controlled concentration gradient to determine the optimal concentration of ursolic acid in the wound healing process. The migration of cells according to different concentrations of ursolic acid was achieved easily, quickly, and reliably, and the effect of ursolic acid in promoting cell migration was confirmed. We demonstrated that our system effectively provides an appropriate environment for in vitro wound healing studies and is expected to be an advanced tool and an economically efficient, robust, and reliable platform to study and evaluate new wound healing drugs in vitro.
Unveiling the structural phase transition and magnetic structure of ternary boride PrIr3B2
Authors: Sharma Shivani , Ritter C , Adroja D T , Stenning Gavin B G
Published: November 2023

We present a comprehensive study of PrIr3B2, which includes a detailed investigation of its crystal and magnetic structure using neutron diffraction. AC and DC magnetization and heat capacity data reveal antiferromagnetic ordering at T
N = 10 K. The heat capacity measurements further exhibit a broad peak near 270 K which is related to a structural transition from P6/mmm to C2/m seen in low temperature x-ray diffraction and neutron diffraction. High intensity neutron diffraction data confirm the long-range ordering of Pr3+ spins, with no apparent magnetic moment on either of the Iridium sites. Two possible magnetic structures with either k
1 = [1,0,0] or k
2 = [½,½,0] fit nearly equally well the neutron diffraction data. However, based on previous magnetization studies on a single crystalline sample it is argued that the second solution with k
2 corresponds to the appropriate magnetic structure of PrIr3B2 below 10 K. In this magnetic structure, the Pr3+ moments are oriented at ∼45° to both the a and b axes, with the c-axis being the hard axis of magnetization. Overall, our results provide new insights into the magnetic and structural properties of PrIr3B2.
Fundamental study on diagnostic reference level quantities for endoscopic retrograde cholangiopancreatography using a C-arm fluoroscopy system
Authors: Ishii Hiroki , Chida Koichi , Inaba Yohei , Abe Keisuke , Onodera Shu , Zuguchi Masayuki
Published: November 2023

The diagnostic reference level (DRL) is an effective tool for optimising protection in medical exposures to patients. However regarding air kerma at the patient entrance reference point (K
a,r), one of the DRL quantities for endoscopic retrograde cholangiopancreatography (ERCP), manufacturers use a variety of the International Electrotechnical Commission and their own specific definitions of the reference point. The research question for this study was whether K
a,r is appropriate as a DRL quantity for ERCP. The purpose of this study was to evaluate the difference between K
a,r and air kerma incident on the patient’s skin surface (K
a,e) at the different height of the patient couch for a C-arm system. Fluoroscopy and radiography were performed using a C-arm system (Ultimax-i, Canon Medical Systems, Japan) and a over-couch tube system (CUREVISTA Open, Fujifilm Healthcare, Japan). K
a,e was measured by an ion chamber placed on the entrance surface of the phantom. Kerma-area product (P
KA) and K
a,r were measured by a built-in P
KA meter and displayed on the fluoroscopy system. K
a,e decreased while K
a,r increased as the patient couch moved away from the focal spot. The uncertainty of the K
a,e/K
a,r ratio due to the different height of the patient couch was estimated to be 75%–94%. K
a,r may not accurately represent K
a,e. P
KA was a robust DRL quantity that was independent of the patient couch height. We cautioned against optimising patient doses in ERCP with DRLs set in terms of K
a,r without considering the patient couch height of the C-arm system. Therefore, we recommend that K
a,r is an inappropriate DRL quantity in ERCP using the C-arm system.
Transformer fault diagnosis based on MPA-RF algorithm and LIF technology
Authors: Yan Pengcheng , Wang JingBao , Wang Wenchang , Li Guodong , Zhao Yuting , Wen Ziming
Published: November 2023

Power transformers are essential components in power systems used to regulate voltage, transmit electrical energy, provide isolation, and match loads. They contribute to efficient and reliable electricity transmission and distribution. However, traditional methods for diagnosing transformer faults are time-consuming, not suitable for online monitoring, and greatly affected by environmental conditions. In this experiment, we propose the use of laser-induced fluorescence (LIF) technology for transformer fault detection. LIF technology is a method for analyzing and detecting specific molecules or atoms in samples. It combines laser technology with fluorescence measurements, making it a powerful analytical tool. It achieves high sensitivity and selectivity in analyzing molecules and atoms by exciting and detecting fluorescence in the sample. This makes it an important technology in scientific research and practical applications. Furthermore, LIF technology has not been previously applied to power transformer fault diagnosis. Therefore, this experiment introduces a transformer fault diagnosis model based on the marine predators algorithm (MPA) optimized random forest (RF) algorithm and LIF spectroscopy technology. Four different oil samples were selected for experimentation: crude oil, thermally faulty oil, partially moist oil, and electrically faulty oil. First, LIF technology for collect spectral images and data from the different fault oil samples. The obtained spectral data was preprocessed using two methods, multivariate scatter correction (MSC) and standardization method (SNV). Then, principal component analysis (PCA) and kernel principal component analysis (KPCA) for reducing the dimensionality of the preprocessed spectral data. Finally, the RF model, MPA-RF model, and PSO-RF model were established; and the reduced data was input into the model for training. Through comparisons of the predictions on the test set, evaluation metrics of the algorithm (including fitting coefficient, MSE, RMSE, and RMSE), and iteration convergence curves, the best transformer fault diagnosis model was identified. The results show that the MSC-KPCA-MPA-RF model has the best matching resule, with a fitting coefficient of 0.9963 and a mean square error of 0.0047. The SNV-PCA-MPA-RF model has the worst fitting effect, with a fitting coefficient of 0.9840 and a mean square error of 0.0199. Through comparisons of the convergence of different models, the MSC-KPCA-MPA-RF model has the best convergence and is the most applicable model for transformer fault diagnosis in this experiment. This model has significant implications for ensuring the safety of the power system.
Research on the intrinsic phase difference of Rayleigh scattering in distributed acoustic sensing
Authors: Wang Chen , Li Di , He Qiujie , Wang Meikun , Wang Jiawen , Wang Weitao , Liu Guangqiang , Wan Na , Liu Shouling , Yao Chunmei , Qu Shuai , Shang Ying
Published: November 2023

The differential cross-phase multiply (DCM) demodulation algorithm based on a 3 × 3 coupler is commonly employed in distributed acoustic systems (DAS) to recover phase information along the sensing fiber. This study investigates the amplitude-spatial resolution response characteristics of the DCM algorithm using 3 × 3 coupler demodulation. Firstly, we theoretically establish the variation of demodulation amplitude in DAS systems due to the intrinsic phase of the signal. Subsequently, we analyze the amplitude-pulse width response curves of the DCM algorithm based on the distribution of demodulated phase error obtained from both experimental and simulation data. The findings reveal a double peaks phenomenon in the amplitude response curves of the DCM demodulation algorithm based on 3 × 3 couplers. We also explore the amplitude response curves for multiple pulse widths and observe that, under the same arm length difference conditions, the double peaks persist. However, this double peak phenomenon is eliminated when the pulse width is less than 21 ns. Therefore, when the width determined by the pulse is greater than 40% of the difference between the light paths, the demodulation will appear double peaks phenomenon.
Effect of DC grounding electrode currents on the corrosion interference behavior of cathodic protection of nearby pipelines
Authors: Chen Xiao , Li Lin , Zhang Boyang , Li Hengfeng , Zhao Lunuo , Zhou Yixi , Wu Weiting
Published: November 2023

When operating a direct current (DC) transmission grounding electrode in single-pole return ground mode, transient currents traverse the soil, generating stray currents. These currents can intensify the corrosion of long-distance transmission pipelines near the grounding electrode, subsequently altering the pipeline’s cathodic protection potential. Previous investigations into the interference of grounding electrodes on pipeline cathodic protection have overlooked the cathodic protection systems themselves. Addressing this gap, we integrated COMSOL’s electrochemical module with its AC/DC module. To corroborate the accuracy of our COMSOL-based models, we devised specific validation experiments. Additionally, we crafted a COMSOL application builder interface to streamline computations. Consequently, we derived a multi-regression function to express the cathodic protection potential of the pipeline under varied factors and executed a regression tree classification for soil resistivity. To pinpoint optimal corrosion protection for pipelines, we simulated the cathodic protection of segmentally isolated pipelines, determining that potential excursions can be notably mitigated. This research offers insights into both disturbance evaluation and protective strategies for DC transmission and pipelines.
Preparation of pH-responsive reversible wettable surfaces and application for oil-water separation
Authors: Zhu Yunhu , Feng Aixin , Yu Jinhai , Zhao Pu
Published: November 2023

With the continuous development of society, the discharge of oily wastewater in daily life and industry has gradually increased, causing considerable damage to the environment, and how to effectively treat oily wastewater is an urgent problem. In this paper, a simple method is proposed to prepare superhydrophobic stainless steel mesh with pH response. The relationship between the ratio of mixed thiols and the surface wettability was explored, as well as the morphology, chemical composition, and pH-responsive mechanism of the stainless steel mesh surface were analyzed, and the separation efficiency, recycling ability, and backwashing ability of the mesh were explored by oil–water separation experiments. It was found that when the molar fraction of 11-mercaptoundecanoic acid and 1-decanethiol in the mixed mercaptan was 2:3, the water contact angle of the surface at this point was 156.5 ± 1°, with pH response characteristics and good oil–water separation efficiency, backwashing and recycling capabilities.
Integrable hierarchies, Frölicher–Nijenhuis bicomplexes and Lauricella bi-flat F-manifolds
Authors: Lorenzoni Paolo , Perletti Sara
Published: November 2023

Given the Frölicher-Nijenhuis bicomplex

(
d
,

d
L

)

associated with a

(
1
,
1
)

-tensor field L with vanishing Nijenhuis torsion, we define a multi-parameter family of bi-flat structures

(
∇
,
e
,
∘
,

∇
∗

,
∗
,
E
)

. This result is obtained by combining the construction of integrable hierarchies of hydrodynamic type starting from Frölicher-Nijenhuis bicomplexes with the construction of flat F-manifold structures from integrable systems of hydrodynamic type. By construction L is the operator of multiplication by the Euler vector field E and the number of parameters coincides with the number of Jordan blocks appearing in its Jordan normal form. We call these structures Lauricella bi-flat structures since in the n-dimensional semisimple case

(
n
−
1
)

flat coordinates of

∇

are Lauricella functions. The

(
1
,
1
)

-tensor fields defining the corresponding integrable hierarchies have a similar block diagonal structure.
MAG-Res2Net: a novel deep learning network for human activity recognition
Authors: Liu Hanyu , Zhao Boyang , Dai Chubo , Sun Boxin , Li Ang , Wang Zhiqiong
Published: November 2023

Objective. Human activity recognition (HAR) has become increasingly important in healthcare, sports, and fitness domains due to its wide range of applications. However, existing deep learning based HAR methods often overlook the challenges posed by the diversity of human activities and data quality, which can make feature extraction difficult. To address these issues, we propose a new neural network model called MAG-Res2Net, which incorporates the Borderline-SMOTE data upsampling algorithm, a loss function combination algorithm based on metric learning, and the Lion optimization algorithm. Approach. We evaluated the proposed method on two commonly utilized public datasets, UCI-HAR and WISDM, and leveraged the CSL-SHARE multimodal human activity recognition dataset for comparison with state-of-the-art models. Main results. On the UCI-HAR dataset, our model achieved accuracy, F1-macro, and F1-weighted scores of 94.44%, 94.38%, and 94.26%, respectively. On the WISDM dataset, the corresponding scores were 98.32%, 97.26%, and 98.42%, respectively. Significance. The proposed MAG-Res2Net model demonstrates robust multimodal performance, with each module successfully enhancing model capabilities. Additionally, our model surpasses current human activity recognition neural networks on both evaluation metrics and training efficiency. Source code of this work is available at: https://github.com/LHY1007/MAG-Res2Net.
Modification of the optical and elastic properties of TlGaSe2 layered semiconductor produced by the memory effect
Authors: Cengiz Asuman , Gören Serdar , Sönmez Ayşe , Şale Yasin , Okumuş Esra , Kırbaş Cafer , Chumakov Yurii M , Seyidov MirHasan Yu
Published: November 2023

A comparative analysis of the temperature behaviors of optical and elastic properties of

TlGa

Se

2

single crystals under a memory effect experimental condition are presented for the first time. A memory effect condition suggests that the sample is thermally annealed inside the incommensurate (INC) phase for a time interval the corresponding physical parameters is measured experimentally. From ultrasound velocity measurements, carried out before and after the thermal annealing process subjected to the sample, the noticeable changes in the temperature variation of the longitudinal ultrasonic wave velocity associated with the elastic constants

C

33

of

TlGa

Se

2

due to the memory effect was detected. Our results reveal that thermal annealing performed at the INC - phase has some influence on the optical absorption of

TlGa

Se

2

crystals in the visible spectral region. We assumed that thermal annealing within INC - phase is accompanied with the appearance, inside

TlGa

Se

2

samples, a new quasiperiodic frozen structure formed from the intrinsic defects migrated into the lowest energy diffusion barriers of the INC - modulation wave. Such structural modulation is incommensurate with the underlying lattice of

TlGa

Se

2

and can lead to changes in the electronic band structure and the optical bandgaps of

TlGa

Se

2

.
Multi-mode vortex beams generation with single-layer transmissive metasurface
Authors: Wang Ziyue , Zhou Dongfang , Liu Qikun , Yan Mengyao , Wang Xian
Published: November 2023

Orbital angular momentum (OAM) is a phenomenon of vortex phase distribution in free space, the infinity of whose modes and the orthogonality between modes allow it to possess great potential in enhancing channel capacity. A transmissive metasurface consisting of a single-layer substrate and a two-layer metallic structure is proposed to enable vortex beam generation based on the concept of the Pancharatnam-Berry (PB) phase. The phase response is achieved by continuous phase modulation under circularly polarised (CP) wave incidence due to the simultaneous rotation of the upper and lower metal structures. Besides, through the introduction of both phase compensation on the metasurface and phase superposition of the beams to the array design, multi-beam generation is expected to be realized. A metasurface sample composed of 30

×

30 elements (450 mm

×

450 mm) is fabricated and measured in a microwave darkroom on the basis of the simulation results. Both the simulation and measurement results provide firm demonstration that the designed metasurface is capable of simultaneously generating four beams carrying OAM mode numbers of

±
1
/
±
2

and different beam directions at the same aperture. The designed metasurface in this paper utilized for generating multi-mode vortex multi-beams will be of wide application in multi-channel transmission in wireless communication systems.
The TSM-net: a new strategy for insulated bearings intelligent faults diagnosis
Authors: Yang Tongguang , Zhao Shubiao , Zhang Junan , Han Qingkai , Li Xuejun
Published: November 2023

With the development of power semiconductor devices, pulse width modulation technology is widely used in high-power frequency conversion control motors, which significantly improves the dynamic performance of variable-speed drive system equipment. However, the high-frequency shaft voltage generated during the drive process acts on the bearing to generate high-frequency current. The damage caused by the shaft current sharply shortens the fatigue wear process of the bearing, which in turn leads to premature failure of the bearing. A high insulating ceramic coating is prepared on the outer surface and side face of the inner and outer rings of the bearing by plasma spraying. That is, an insulating protective film is formed on the outer surface of the bearing, which can effectively isolate or reduce the bearing current, prevent the occurrence of electric erosion, and prolong the service life of the variable speed drive system equipment. However, the vibration excitation generated by the variable-speed drive system equipment will cause cracks or fatigue damage to the insulating bearing, resulting in a very complex fault mechanism of the vibration signal. The fault signal characterization lacks a professional signal analysis method, especially the high-reliability, high-precision and long-life high-performance insulating bearing. There is no qualitative formula or characteristic index to explain its failure. To fill this research gap, a new strategy for optimizing the temporal information fusion model and introducing the self-attention mechanism is innovatively developed, and it is named TSM-Net model, and the first attempt is made to realize intelligent identification of insulated bearing faults. Specifically, a multi-channel insulated bearing time information fusion diagnostic model is designed, and the coarse-grained characteristics with timing law are extracted from the measured insulated bearing fault data. Then, the self-attention mechanism is introduced into the designed insulated bearing time information fusion diagnostic model to optimize, and the weight coefficient is continuously updated to calculate the correlation weight between the insulated bearing fault data and the data, so that the final decision of the TSM-Net model is more focused, so as to improve the diagnostic accuracy. Finally, comparing the proposed TSM-Net model with the current five advanced methods, it is found that the proposed TSM-Net model has good diagnostic accuracy for rail transit motor insulated bearing faults, which verifies the effectiveness and superiority of the strategy, and provides a new way for the fault diagnosis of insulated bearings of high-power inverter control motors.
Statistical analysis of porcelain tiles’ technical properties: full factorial design investigation on oxide ratios and temperature
Authors: Zamani Mohsen , Yapicioglu Haluk , Kara Alpagut , Sevik Cem
Published: November 2023

This study focuses on optimizing the composition and firing temperature of porcelain tiles using statistical analysis techniques. A full factorial design, including model adequacy checking, analysis of variance, Pareto charts, interaction plots, regression model, and response optimizer is employed. The key factors were the Seger ratios of SiO2/Al2O3, Na2O/K2O, MgO/CaO, and firing temperature. The response variables investigated were bulk density, water absorption, linear shrinkage, coefficient of thermal expansion (at 500 °C), and strength. The statistical analysis revealed highly significant results, which were further validated, confirming their reliability for practical use in the production of porcelain tiles. The study demonstrated the effectiveness of utilizing Seger formulas and properties of typical raw materials to accurately predict the final properties of ceramic tiles. By employing SiO2/Al2O3 = 5.2, Na2O/K2O = 1.50, MgO/CaO = 3.0, and firing temperature of 1180 °C, optimized properties, such as maximum strength, maximum bulk density, and minimum water absorption, was achieved with a composite desirability of 0.9821.
Metastable cosmic strings
Authors: Buchmüller Wilfried , Domcke Valerie , Schmitz Kai
Published: November 2023

Many symmetry breaking patterns in grand unified theories (GUTs) give rise to cosmic
strings that eventually decay when pairs of GUT monopoles spontaneously nucleate along the string
cores. These strings are known as metastable cosmic strings and have intriguing implications for
particle physics and cosmology. In this article, we discuss the current status of metastable
cosmic strings, with a focus on possible GUT embeddings and connections to inflation, neutrinos,
and gravitational waves (GWs). The GW signal emitted by a network of metastable cosmic strings in
the early universe differs, in particular, from the signal emitted by topologically stable strings
by a suppression at low frequencies. Therefore, if the underlying symmetry breaking scale is close
to the GUT scale, the resulting GW spectrum can be accessible at current ground-based
interferometers as well as at future space-based interferometers, such as LISA, and at the same
time account for the signal in the most recent pulsar timing data sets. Metastable cosmic strings
thus nourish the hope that future GW observations might shed light on fundamental physics close to
the GUT scale.
Highly asymmetric probability distribution from a finite-width upward step during inflation
Authors: Kawaguchi Ryodai , Fujita Tomohiro , Sasaki Misao
Published: November 2023

We study a single-field inflation model in which the inflaton potential has an upward step between two slow-roll regimes by taking into account the finite width of the step. We calculate the probability distribution function (PDF) of the curvature perturbation P[ℛ] using the  δNformalism. The PDF has an exponential-tail only for positive ℛ whose slope depends on the step width. We find that the tail may have a significant impact on the estimation of the primordial black hole abundance. We also show that the PDF P[ℛ] becomes highly asymmetric on a particular scale exiting the horizon before the step, at which the curvature power spectrum has a dip. This asymmetric PDF may leave an interesting signature in the large scale structure such as voids.
Reheating process in the R
2 inflationary model with the baryogenesis scenario
Authors: Jeong Hyun , Kamada Kohei , Starobinsky Alexei A. , Yokoyama Jun'ichi
Published: November 2023

Post-inflationary evolution and (re)heating of the viable inflationary model, the R
2 one, is made more realistic by including the leptogenesis scenario into it. For this purpose, right-handed Majorana neutrinos with a large mass are added to the matter sector of the Standard Model to explain the neutrino oscillation experiments and the baryon asymmetry of the Universe. We have found parameters that characterize this model: non-minimal coupling of the Higgs field ξ, the mass of the right-handed Majorana neutrino MN
α
and the Yukawa coupling matrix components for the right-handed Majorana neutrino. We have analyzed the effect of these parameters on the reheating process and leptogenesis in this model and how they affect the resultant physical quantities: spectral parameters of primordial perturbations and baryon asymmetry.
The polarization quaternion and its applications: a joint representation
of the Q/U Stokes parameters and E/B mode polarizations
Authors: Liu Hao , Creswell James , Tsai Chao-Wei , Naselsky Pavel
Published: November 2023

In this work, we point out that the Q/U Stokes parameters and E/B mode
polarizations are the four components of a unique quaternion, which describes at
the same time the directions and the parity states of spherical linear
polarizations. We then point out that, with this polarization quaternion, the
mathematical form of all Q/U and E/B transforms are greatly simplified, to an
extent that requires only one quaternion multiplication for each transform. A
preliminary application of the polarization quaternion is shown as an example to
detect peculiar pixel domain patterns within the E- and B-families, which are
the former and latter halves of the polarization quaternion.
Spectro-spatial evolution of the CMB. Part II. Generalised Boltzmann hierarchy
Authors: Chluba Jens , Ravenni Andrea , Kite Thomas
Published: November 2023

In this paper, we formulate a generalised photon Boltzmann hierarchy that allows us to
model the evolution and creation of spectral distortion anisotropies caused by energy
release in the early Universe. We directly build on our first paper in this series, extending
the thermalisation Green's function treatment to the anisotropic case. We show that the problem
can be described with the common Boltzmann hierarchy for the photon field extended by new spectral
parameters — a step that reduces the complexity of the calculation by at least two orders of
magnitude. Our formalism describes the effects of i) Doppler and potential driving, ii) spectral
evolution by Compton scattering, iii) perturbed thermalisation and iv) anisotropic heating on the
distortion anisotropies. We highlight some of the main physical properties of the equations and
also outline the steps for computing CMB power spectra including distortion
anisotropies. Limitations and extensions of the formulation are also briefly discussed. The novel
Boltzmann hierarchy given here is the basis for a series of companion papers studying how
distortion anisotropies evolve in the perturbed Universe and which physical processes could be
constrained using future CMB imaging techniques.
Parity-violating trispectrum from Chern-Simons gravity
Authors: Creque-Sarbinowski Cyril , Alexander Stephon , Kamionkowski Marc , Philcox Oliver
Published: November 2023

A potential source for parity violation in the Universe is inflation. The simplest
inflationary models have two fields: the inflaton and graviton, and the lowest-order
parity-violating coupling between them is dynamical Chern-Simons (dCS) gravity with a decay
constant f. Here, we show that dCS imprints a parity-violating signal in primordial scalar
perturbations. Specifically, we find that, after dCS amplifies one graviton helicity due to a
tachyonic instability, the graviton-mediated correlation between two pairs of scalars develops a
parity-odd component. This correlation, the primordial scalar trispectrum, is then transferred to
the corresponding curvature correlator and thus is imprinted in both large-scale structure (LSS)
and the cosmic microwave background (CMB). We find that the parity-odd piece has roughly the same
amplitude as its parity-even counterpart, scaled linearly by the degree of gravitational circular
polarization Πcirc ∼ √ε[h
2/(M
Pl
f)] ≤ 1, with
 ε the slow-roll parameter, H the inflationary Hubble scale, and the upper bound
saturated for purely circularly-polarized gravitons. We also find that, in the collapsed limit,
the ratio of the two trispectra contains direct information about the graviton's spin. In models
beyond standard inflationary dCS, e.g. those with multiple scalar fields or superluminal scalar
sound speed, there can be a large enhancement factor F ≳ 106 to the trispectrum. We find
that an LSS survey that contains N
modes linear modes would place an nσ constraint
on Πcirc

r
of ∼ 0.04 (n/3)(106/F)(106/N
modes)1/2 from the parity-odd
galaxy trispectrum, for tensor-to-scalar ratio r. We also forecast for several spectroscopic and
21-cm surveys. This constraint implies that, for high-scale single-field inflation parameters, LSS
can probe very large dCS decay constants f ≲ 4 × 109 
GeV(3/n)(F/106)(N
modes/106)1/2. Our result is the first example of a
massless particle yielding a parity-odd scalar trispectrum through spin-exchange.
Global and local stability for ghosts coupled to positive energy degrees of freedom
Authors: Deffayet Cédric , Held Aaron , Mukohyama Shinji , Vikman Alexander
Published: November 2023

Negative kinetic energies correspond to ghost degrees of freedom, which are potentially of
relevance for cosmology, quantum gravity, and high energy physics. We present a novel wide class
of stable mechanical systems where a positive energy degree of freedom interacts with a
ghost. These theories have Hamiltonians unbounded from above and from below, are integrable, and
contain free functions. We show analytically that their classical motion is bounded for all
initial data. Moreover, we derive conditions allowing for Lyapunov stable equilibrium points. A
subclass of these stable systems has simple polynomial potentials with stable equilibrium points
entirely due to interactions with the ghost. All these findings are fully supported by numerical
computations which we also use to gather evidence for stability in various nonintegrable systems.
Axial perturbations of black holes in scalar-tensor gravity:
near-horizon behaviour
Authors: Noui Karim , Roussille Hugo , Langlois David
Published: November 2023

We consider axial (or odd-parity) perturbations of non-spinning hairy black holes (BH) in shift-symmetric DHOST (Degenerate Higher-Order Scalar-Tensor) theories, including terms quartic and cubic in second derivatives of the scalar field.
We give a new formulation of the effective metric in which axial perturbations propagate as in general relativity. We then introduce a generic parametrization of the effective metric in the vicinity of the background BH horizon. Writing the dynamics of the perturbations in terms of a Schrödinger-like operator, we discuss in which cases the operator is (essentially) self-adjoint, thus leading to an unambiguous time evolution, according to the choice of parameters characterizing the near-horizon effective metric. This is in particular useful to investigate the stability of the perturbations.
We finally illustrate our general analysis with two examples of BH solutions.
A test of gravity with Pulsar Timing Arrays
Authors: Liang Qiuyue , Lin Meng-Xiang , Trodden Mark
Published: November 2023

A successful measurement of the Stochastic Gravitational Wave Background (SGWB) in Pulsar Timing Arrays (PTAs) would open up a new window through which to test the predictions of General Relativity (GR). We consider how these measurements might reveal deviations from GR by studying the overlap reduction function — the quantity that in GR is approximated by the Hellings-Downs curve — in some sample modifications of gravity, focusing on the generic prediction of a modified dispersion relation for gravitational waves. We find a distinct signature of such modifications to GR — a shift in the minimum angle of the angular distribution — and demonstrate that this shift is quantitatively sensitive to any change in the phase velocity. In a given modification of gravity, this result can be used, in some regions of parameter space, to distinguish the effect of a modified dispersion relation from that due to the presence of extra polarization modes.
GEO-FPT: a model of the galaxy bispectrum at mildly non-linear scales
Authors: Novell-Masot Sergi , Gualdi Davide , Gil-Marín Héctor , Verde Licia
Published: November 2023

We present GEO-FPT (Geometric Fitted Perturbation Theory), a new model for the galaxy bispectrum anisotropic signal in redshift space, with functional form rooted in perturbation theory. It also models the dependence of the bispectrum with the geometric properties of the triangles in Fourier space, and has a broader regime of validity than
state-of-the-art theoretical models based on perturbation theory. We calibrate the free parameters of this model using high-resolution dark matter simulations and perform stringent tests to show that GEO-FPT
describes the galaxy bispectrum accurately up to scales of k ≃ 0.12hMpc-1 for different cosmological models, as well as for biased tracers of the dark matter field, considering a survey volume of 100 (Gpc h-1)3. In particular, a joint analysis of
the power spectrum and bispectrum anisotropic signals, taking into account their full covariance matrix, reveals that the
relevant physical quantities —
the BAO peak position (along and across the line-of-sight), and the growth of structure parameters times the amplitude of dark matter fluctuations, fσ
8 — are recovered in an unbiased way, with an accuracy better than 0.4% and 2% respectively (which is our 2σ statistical limit of the systematic error estimate).
In addition, the bispectrum signal breaks the fσ
8 degeneracy without detectable bias: f and σ
8 are recovered with better than 2.7% and 3.8% accuracy respectively (which is our 2σ statistical limit of the systematic error estimate).

GEO-FPT boosts the applicability of the bispectrum signal of galaxy surveys beyond the current limitation of k ≲ 0.08hMpc-1 and makes the bispectrum a key statistic to unlock the information content from the mildly non-linear regime in the on-going and forthcoming galaxy redshift surveys.
Separability and classification of multipartite quantum states
Authors: Ma Pan-Wen , Zhao Hui , Jing Naihuan
Published: November 2023

We study separability in arbitrary multipartite quantum systems based on principal base matrices. Necessary conditions are presented for different kinds of separable states. These conditions can give a complete classification of multipartite quantum states. While the usual Bloch representation of a density matrix uses three types of generators, the representation with principal base matrices has one uniform type of generator which simplifies computation. In this paper, we take advantage of this simplicity to derive useful and operational criteria to detect multipartite separability. We first obtain criteria on detecting

1
−
3

separable,

2
−
2

separable,

1
−
1
−
2

separable and fully separable four-partite quantum states. We then study k-separability for multipartite quantum states in arbitrary dimensions. Detailed examples are given to show that our criteria are able to detect more entanglement states than some existing criteria.
Stationary state of harmonic chains driven by boundary resetting
Authors: Sarkar Ritwick , Roy Pritam
Published: November 2023

We study the nonequilibrium steady state of an ordered harmonic chain of N oscillators connected to two walls which undergo diffusive motion with stochastic resetting. The intermittent resetting of the walls effectively emulates two nonequilibrium reservoirs that exert temporally correlated forces on the boundary oscillators. These reservoirs are characterized by the diffusion constants and resetting rates of the walls. We find that, for any finite N, the velocity distribution of the bulk oscillators remains non-Gaussian, as evidenced by a non-zero bulk kurtosis that decays

∼

N

−
1

. We calculate the spatio-temporal correlation of the velocity of the oscillators

⟨

v
l

(
t
)

v

l

′

(

t

′

)
⟩

both analytically as well as using numerical simulation. The signature of the boundary resetting is present at the bulk in terms of the two-time velocity correlation of a single oscillator and the equal-time spatial velocity correlation. For the resetting driven chain, the two-time velocity correlation decay as

t

−

1
2

at the large time, and there exists a non-zero equal-time spatial velocity correlation

⟨

v
l

(
t
)

v

l

′

(

t

′

)
⟩

when

l
≠

l

′

. A non-zero average energy current will flow through the system when the boundary walls reset to their initial positions at different rates. This average energy current can be computed exactly in the thermodynamic limit. Numerically we show that the distribution of the instantaneous energy current at the boundary is independent of the system size. However, the distribution of the instantaneous energy current in the bulk approaches a stationary distribution in the thermodynamic limit.
Beam test result of the sealed MRPC prototype for CEE-eTOF
Authors: Wang Botan , Xu Haoqian , Sun Kai , Liu Daming , Han Dong , Wang Yi , Zhao Lei , Guo Baohong , Wang Hexiang , Huang Shiya
Published: November 2023

We report the beam test and result of the sealed Multigap Resistive Plate Chambers (MRPC) for the external Time of Flight (eTOF) wall of the Cooler-strorage-ring External-target Experiment (CEE). The test stand detects the secondary charged particles produced from heavy ion collisions in the Heavy Ion Research Facility in Lanzhou (HIRFL), and it serves as a joint evaluation of the future CEE system, including the detectors, readout electronics, data acquisition, trigger system, etc. The collision is achieved by a Fe beam and a Fe target, with an estimated beam energy of 300 MeV/u. The sealed MRPC prototypes work stably during the test with a 20 sccm low gas flow. The whole test system is triggered from the channel multiplicity provided by the TOF detectors. A tracking method is implemented to the analysis in order to resolve the events with multiple tracks on the detectors. The result shows that the detectors reach 98% efficiency at their working point. With proper corrections, the time resolution is evaluated to be 60 ps, which fulfills the requirement to the eTOF wall.
Generalizing to new geometries with Geometry-Aware Autoregressive Models (GAAMs) for fast calorimeter simulation
Authors: Liu Junze , Ghosh Aishik , Smith Dylan , Baldi Pierre , Whiteson Daniel
Published: November 2023

Generation of simulated detector response to collision products is crucial to data analysis in particle physics, but computationally very expensive. One subdetector, the calorimeter, dominates the computational time due to the high granularity of its cells and complexity of the interactions. Generative models can provide more rapid sample production, but currently require significant effort to optimize performance for specific detector geometries, often requiring many models to describe the varying cell sizes and arrangements, without the ability to generalize to other geometries. We develop ageometry-awareautoregressive model, which learns how the calorimeter response varies with geometry, and is capable of generating simulated responses to unseen geometries without additional training. The geometry-aware model outperforms a baseline unaware model by over 50% in several metrics such as the Wasserstein distance between the generated and the true distributions of key quantities which summarize the simulated response. A single geometry-aware model could replace the hundreds of generative models currently designed for calorimeter simulation by physicists analyzing data collected at the Large Hadron Collider. This proof-of-concept study motivates the design of a foundational model that will be a crucial tool for the study of future detectors, dramatically reducing the large upfront investment usually needed to develop generative calorimeter models.
CNR performance of semiconductor materials for X-ray imaging of breast calcifications
Authors: Mendoza L. , Avila C. , Rodríguez R. , Loaiza L. , Roque G.
Published: November 2023

We present the results of a GAMOS/GEANT4 computer simulation
of a standard X-ray mammography system, which consists of a Tungsten
28 kVp polychromatic X-ray source with a 50 μm Rh filter, a
mammography phantom with Al2O3 spherical specks of different
diameters, and a generic pixel detector
(55 μm × 55 μm pixel size) with different
types of semiconductor sensors. The number of photons simulated is
calibrated to produce similar entrance surface dose (ESD) as the one
used by a standard clinical mammography screening. Estimates of
Contrast to Noise Ratio (CNR) as a function of ESD, sensor thickness
and microcalcification diameter are presented for four different
sensor materials: Silicon (Si), Cadmium Telluride (CdTe), Gallium
Arsenide (GaAs) and Perovskite (MAPbI3). For the X-ray energy
spectrum and pixel size considered, and an ESD dose of 4 mGy, our
study shows that, with the exception of Si, these sensors, as thin
as 200 μm, are able to resolve (with at least 3 standard
deviations above background) Al2O3 spherical specks up to a
minimum diameter of 180 μm, having statistically compatible
CNR performance. The increase in substrate thickness has a
substantial improvement in the CNR values provided by the Si sensor,
while for the other cases the enhancement of CNR is marginal and
consistent with statistical uncertainties with the thinnest case
considered.
Environmental force sensing helps robots traverse cluttered large obstacles
Authors: Xuan Qihan , Li Chen
Published: November 2023

Robots can traverse sparse obstacles by sensing environmental geometry and avoiding contact with obstacles. However, for search and rescue in rubble, environmental monitoring through dense vegetation, and planetary exploration over Martian and lunar rocks, robots must traverse cluttered obstacles as large as themselves by physically interacting with them. Previous work discovered that the forest floor-dwelling discoid cockroach and a sensor-less minimalistic robot can traverse cluttered grass-like beam obstacles of various stiffness by transitioning across different locomotor modes. Yet the animal was better at traversal than the sensor-less robot, likely by sensing forces during obstacle interaction to control its locomotor transitions. Inspired by this, here we demonstrated in simulation that environmental force sensing helps robots traverse cluttered large obstacles. First, we developed a multi-body dynamics simulation and a physics model of the minimalistic robot interacting with beams to estimate beam stiffness from the sensed contact forces. Then, we developed a force feedback strategy for the robot to use the sensed beam stiffness to choose the locomotor mode with a lower mechanical energy cost. With feedforward pushing, the robot was stuck in front of stiff beams if it has a limited force capacity; without force limit, it traversed but suffered a high energy cost. Using obstacle avoidance, the robot traversed beams by avoiding beam contact regardless of beam stiffness, resulting in a high energy cost for flimsy beams. With force feedback, the robot determined beam stiffness, then traversed flimsy beams by pushing them over and stiff beams by rolling through the gap between them with a low energy cost. Stiffness estimation based on force sensing was accurate across varied body oscillation amplitude and frequency and position sensing uncertainty. Mechanical energy cost of traversal increased with sensorimotor delay. Future work should demonstrate cluttered large obstacle traversal using force feedback in a physical robot.