bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic characteristics and energy performance of a magnetically induced multi-array piezoelectric energy harvester with asymmetric potential wells
Authors: Li Yue , Xu Mao , Zhou Gongbo , Xie Heng , Yan Xiaodong
Published: October 2024

Piezoelectric energy harvesting technology is a promising strategy for powering wireless sensor networks. However, piezoelectric energy harvesters (PEHs), especially linear PEHs, usually have narrow operating frequency bandwidth. In this study, in order to broaden frequency bandwidth, a nonlinear multi-stable magnetically induced PEH array (MPEHA) with asymmetric potential wells is proposed. Specifically, the proposed MPEHA is consisted of piezoelectric energy harvesting technique, multi-resonance array technique and magnetic force based nonlinear technique. Both theoretical and experimental studies are conducted to investigate the energy performance and to analyze the dynamic characteristics of MPEHA with snap-through motions among the multiple stable positions. As for theoretical study, a mathematic model of the potential function of the proposed harvester is established and the influence of magnetic force on the potential well configuration is quantitively investigated. As for experimental study, experiments including open-circuit voltage experiment and capacitance charging experiment are conducted using MPEHA with three-beam arrays. Our experimental study demonstrates that MPEHA has better performance than the traditional PEHA due to the magnetic coupling effect. Under excitation acceleration of 3 m s−2, the performance of bi-stable MPEHA is improved by 80.2%, compared with PEHA.
High-speed airflow influence on adhesion performance of fibrillar adhesive
Authors: Chen Wenqing , Sun Tianhui , Li Jingyang , Li Xiaosong , Li Xinxin , Meng Yonggang , Tian Yu
Published: October 2024

Bio-inspired adhesives have been widely studied in various fields, including attachment and grasping technologies in sea, land, air, and space. However, current research primarily focuses on static and quasi-static scenarios, necessitating further exploration in achieving adhesion on high-speed moving objects, such as railroads and automobiles. In this study, we explore a representative adhesive system comprising a fibrillar adhesive layer and a backing structure contacting with a smooth substrate in high-speed airflow. The investigation into adhesion performance was conducted by finite element analysis, theoretical analysis, and experimental approaches. Our findings indicate that the impact of high-speed airflow on microfiber structure deformation primarily manifests within the initial 1–2 rows on the windward side, yet remains insufficient to significantly influence adhesion. The adhesion capacity of the adhesive composite in high-speed airflow is mainly determined by the elastic modulus of the backing structure and the deformation offset, exhibiting a straightforward linear relationship with their product. Moreover, an optimization strategy of adding a cowling to the adhesive composite with soft backing was proposed to preserve its high loading capacity. These findings present a comprehensive understanding of the loading mechanism of fibrillar adhesive composite in high-speed airflow and provide new insights into robust reversible adhesion design for related technologies.
Analysis of multi-term arbitrary order implicit differential equations with variable type delay
Authors: ur Rahman Ghaus , Wahid Fazal , Gómez-Aguilar J F , Ali Amjad
Published: October 2024

Due to their capacity to simulate intricate dynamic systems containing memory effects and non-local interactions, fractional differential equations have attracted a great deal of attention lately. This study examines multi-term fractional differential equations with variable type delay with the goal of illuminating their complex dynamics and analytical characteristics. The introduction to fractional calculus and the justification for its use in many scientific and technical domains sets the stage for the remainder of the essay. It describes the importance of including variable type delay in differential equations and then applying it to model more sophisticated and realistic behaviours of real-world phenomena. The research study then presents the mathematical formulation of variable type delay and multi-term fractional differential equations. The system’s novelty stems from its unique combination of variable delay, generalized multi terms fractional differential operators (n and m), and integral implicit parameters, and studying the stability of the the newly formulated system as compared to the work in the existing literature. While the variable type delay is introduced as a function of time to describe instances where the delay is not constant, the fractional order derivatives are generated using the Caputo approach. The existence, uniqueness, and stability of solutions are the main topics of the theoretical analysis of the suggested differential equations. In order to establish important mathematical features, the inquiry makes use of spectral techniques, and fixed-point theorems. The study finishes by summarizing the major discoveries and outlining potential future research avenues in this developing field. It highlights the potential contribution of multi-term fractional differential equations with variable type delay to improving the control and design of complex systems. Overall, this study adds to the growing body of knowledge in the field of fractional calculus and provides insightful information about the investigation of multi-term fractional differential equations with variable type delay, making it pertinent for academics and practitioners from a variety of fields.
Comprehensive study of epitaxial (Nd,Eu,Gd)Ba2Cu3O7−δ
films grown on textured templates
Authors: Shipulin Ilya A , Nielsch Kornelius , Hühne Ruben
Published: October 2024

We report the successful epitaxial growth and comprehensive study of structural and superconducting properties of (Nd,Eu,Gd)Ba2Cu3O7−δ
films with a thickness of up to 1.2 μm prepared by on-axis pulsed laser deposition on SrTiO3 (STO) single crystals as well as on ion-beam-assisted deposition (IBAD) and rolling-assisted biaxially textured substrate (RABiTS)-based metal templates. X-ray diffraction demonstrates the epitaxial quality of the grown films on both single crystalline substrates and metal-based templates. In addition, no significant changes in surface morphology were found with increasing thickness for films on all types of substrates. On all substrates, a T
c value of about 89 K was observed, however, significant inhomogeneities indicating small superconducting volume were found for all films on STO. In general, the best transport characteristics over a wide range of magnetic fields and temperatures were observed for thicker films on IBAD-MgO and RABiTS templates, respectively. The J
c values at 77 K for the films on IBAD-MgO templates are comparable to YBCO films, but inferior in the low temperature region and high magnetic fields, whereas the films on RABiTS and especially on STO showed much lower J
c over the entire temperature and magnetic field range. A maximum pinning force of about 7 GN·m−3 at 65 K was found for the 900 nm thick films on IBAD-MgO template. In addition, the pinning mechanism seems to depend on both temperature and type of substrate. In general, no correlation between local microstructure and transport characteristics was revealed for NEG films on both metal templates.
Optimization and analysis of Si/SiGe strained vertically stacked heterostructure on insulator FeFinFET for high performance analog and RF applications
Authors: Verma Kajal , Chaujar Rishu
Published: October 2024

As semiconductor technology advances, the exploration of novel materials and device architectures becomes imperative to meet the growing demands of integrated circuits for analog and radio-frequency (RF) applications. In this paper, various advanced technologies have been amalgamated such as integration of ferroelectric layer in multigate FinFET along with the adaptation of SOI technology. Further strain technology is also used which employs a tri-layered strained-silicon channel system with the help of SiGe to form Vertically Stacked Heterostructure on Insulator Ferroelectric based FinFET (VS-HOI-FeFinFET) and on comparison with baseline FeFinFET, it is found to show remarkable improvements in terms of various measured parameters such as drain current, switching ratio, threshold voltage and subthreshold swing. Subsequently, gate stacking architecture is incorporated in VS-HOI-FeFinFET to further optimize the device performance. The four different configurations C1 to C4 are taken in terms of four different combinations of gate stack materials considered for gate oxide such as C1(SiO2+Al2O3), C2(SiO2+HfO2), C3(Al2O3), and C4(Al2O3+HfO2). It is found that the static and analog performance of VS-HOI-GS-FeFinFET enhance sequentially from configuration C1 to C4 such as switching ratio is enhanced upto around 5 times, DIBL and quality factor are improved by around 41% and 58% respectively along with significant improvement in device efficiency, early voltage, intrinsic gain, output conductance and output resistance. Subsequently performance optimization of VS-HOI-GS-FeFinFET with variation in mole fraction of germanium is also explored for various analog metrics. Further, several RF parameters are also explored and it is observed that the gain frequency product (GFP) and gain transconductance frequency product (GTFP) are augmented by around three times in magnitude along with 16% reduction in the unity gain cut off frequency in C4 configuration, exhibiting its ability of high frequency amplification with minimized noise distortion thus makes the device suitable for various high performance Analog and RF applications.
Cosmic-ray propagation models elucidate the prospects for antinuclei detection
Authors: Luque Pedro De La Torre , Winkler Martin Wolfgang , Linden Tim
Published: October 2024

Tentative observations of cosmic-ray antihelium by the AMS-02 collaboration have re-energized the quest to use antinuclei to search for physics beyond the standard model. However, our transition to a data-driven era requires more accurate models of the expected astrophysical antinuclei fluxes. We use a state-of-the-art cosmic-ray propagation model, fit to high-precision antiproton and cosmic-ray nuclei (B, Be, Li) data, to constrain the antinuclei flux from both astrophysical and dark matter annihilation models. We show that astrophysical sources are capable of producing 𝒪(1) antideuteron events and 𝒪(0.1) antihelium-3 events over 15 years of AMS-02 observations. Standard dark matter models could potentially produce higher levels of these antinuclei, but showing a different energy-dependence. Given the uncertainties in these models, dark matter annihilation is still the most promising candidate to explain preliminary AMS-02 results. Meanwhile, any robust detection of antihelium-4 events would require more novel dark matter model building or a new astrophysical production mechanism.
Revisiting astrophysical bounds on continuous spontaneous localization models
Authors: Ocampo M.M. , Miller Bertolami M.M. , León G.
Published: October 2024

Among the open problems in fundamental physics, few are as conceptually significant as the “measurement problem” in Quantum Mechanics. One of the proposed solutions to this problem is the Continuous Spontaneous Localization (CSL) model, which introduces a non-linear and stochastic modification of the Schrödinger equation. This model incorporates two parameters that can be subjected to experimental constraints. One of the most notable consequences of this theory is the spontaneous heating of massive objects; this anomalous heating is dependent on the CSL parameters. In this work, we will revisit some astrophysical bounds previously found, and introduce new methods for testing the spontaneous heating in a variety of compact objects. Finally, we will compare our different bounds and discuss the benefits and shortcomings of each one.
Effect of local wall clearance on scrape-off layer electron density profiles in ASDEX Upgrade
Authors: Tal B. , Wolfrum E. , Bernert M. , Birkenmeier G. , Brida D. , Fischer R. , Grenfell G. , Griener M. , Grover O. , Hobirk J. , Kurzan B. , Lunt T. , Schneider P.A. , Vianello N. , Wendler D. , Upgrade Team the ASDEX ,   the EUROfusion Tokamak Exploitation Team
Published: October 2024

The plasma electron density is measured with multiple diagnostics in the scrape-off layer of the ASDEX Upgrade tokamak. The recorded values are typically in good agreement in the case of exponentially decaying profiles at low densities, but they become inconsistent as soon as a density shoulder is formed, and up to a factor of 3 deviation is experienced at high densities. An idea is put forward; namely, that the local plasma-wall proximity has an influence on the local density and thus the measurement results depend on the local limiter-plasma and limiter-diagnostic distances at the same time. The effect of local wall clearance dependence is demonstrated by creating a plasma having an extremely high scrape-off layer density

(

n

e

>
3
⋅

10

19

m

−
3

)

after the H-L back transition and varying the position of the separatrix in different directions. As a possible physical process, neutral recycling at the plasma facing components is identified. Similar behaviour is also observed in the QCE regime, where the appearance of small ELMs barely impacts the scrape-off layer profiles. There are also indications that the local wall clearance does have an impact on the density profile not only in the scrape-off layer, but also in the confined region.
An upgrade of the radial probes for HIRFL-SFC
Authors: Kang Xincai , Li Youtang , Chen Yucong , Song Haihong , Mao Ruishi , Zhao Tiecheng
Published: October 2024

SFC (Sector Focusing Cyclotron) is essential to the Heavy
Ion Research Facility in Lanzhou (HIRFL). Its beam extraction
efficiency is directly related to the overall operational efficiency
of the accelerator. The original radial probes of the SFC, due to
its outdated equipment, no longer meet the requirements for beam
tuning in terms of mechanical precision, vacuum level, and local
noise. Three new sets of radial probes have been developed in
phases. These devices were installed at the accelerator site during
annual maintenance, providing axial and radial beam distribution
during acceleration. Since 2020, the system has been operating
without any failures, providing corresponding beam parameters for
the accelerator's operation and ensuring the normal functioning of
the accelerator.
5G network performance using novel MIMO mixed FSO/MMW communication systems under pointing errors effect: test analysis using image transmission
Authors: Derouiche Samra , Kameche Samir , Adardour Haroun Errachid
Published: October 2024

Millimeter waves (MMW) enable high data rates over short distances; free-space optical (FSO) provides high-capacity optical wireless transmissions; and multiple-input multiple-output (MIMO) maximizes antenna utilization. These are the three leading technologies that work harmoniously to deliver 5G’s superior performance. This collaborative effort results in 5G’s ability to offer high connection capacities, low latency, and rapid speeds, creating new opportunities for industrial and internet of things applications. In this paper, the proposed system combines FSO links and MMW radio frequency (RF) links to enhance the performance of mixed FSO/RF systems. FSO experiences turbulence and pointing errors (PE), while MMW undergoes fading. Using both FSO and MMW provides diversity against channel fading. Furthermore, both the FSO and MMW links utilize MIMO technology to combat fading through spatial diversity. The FSO link is modeled with a Gamma-Gamma Turbulence model and PE. The MMW link is modeled with Rayleigh fading. By combining these two types of links with MIMO, the system can achieve improved performance compared to using either FSO or MMW alone. The dual nature of the system provides robustness against different types of channels fading effects. Overall, the goal is to enhance performance by capitalizing on the complementary channel characteristics of optical and RF links and exploiting MIMO’s spatial diversity benefits. In the present work, closed-form formulas accounting for the influence of PE are generated for the bit error rate (BER). This article also explores the MIMO mixed FSO/MMW system with multiple modulation techniques under various turbulence situations. The suggested system is ultimately verified by transmitting images with suitable fixed BER.
Optimized-selenization preparation and laser Q-switching characteristics of layered PtSe2
Authors: Zhang Qianyong , Wang Jing , Li Guoshun , Wang Jinhu , Yue Xiuhui , Guo Heze , Jiang Kai , Xia Wei , Tang Wenjing
Published: October 2024

PtSe2 has high carrier mobility, excellent electrical and optical properties, and high potential in the field of optoelectronic devices. In this paper, the conventional selenization method is optimized and a single-temperature zone preparation is used to prepare large-area and homogeneous PtSe2 thin-film materials on sapphire substrates in a shorter time and at a lower temperature. The prepared sample is characterized by optical microscopy, atomic force microscopy, Raman spectroscopy and Z-scan method. The saturable absorption properties of layered PtSe2 as a passive Q-switched are investigated in a solid-state laser. The results show that the PtSe2 thin film material is synthesized at 400 °C for 1 h to cover the entire one-inch sapphire wafer with a thickness of about 25 nm and the surface roughness is 13.1 nm. The modulation at 1064 nm yielded an output pulse with a maximum repetition frequency of 688.47 kHz, corresponding to a pulse width of 202.5 ns, a peak power of 7.35 W, a single-pulse energy of 1.51 μJ, and a stable pulse train.
A study on interactive fiber rubber composite structures subjected to bend-twist coupling
Authors: Annadata Achyuth Ram , Endesfelder Anett , Koenigsdorff Markus , Mersch Johannes , Gereke Thomas , Zimmermann Martina , Cherif Chokri
Published: October 2024

This paper investigates the deformation behavior of shape memory alloy (SMA)-integrated fiber-reinforced composites, with an emphasis on how different fiber orientations influence bend-twist coupling. The study combines experimental analysis, finite element simulations using Ansys, and analytical modeling via Classical Laminate Theory (CLT) to assess the mechanical response of these composites. The experiments revealed that composites with higher fiber angles (60°) exhibited dominant twisting behavior, while those with lower angles (30° and 45°) showed more pronounced bending deformation. The simulations corroborated these trends, offering detailed insights into the displacement behavior. The CLT model further predicted a decrease in deflection with increasing fiber angles, which was consistent with experimental results, although some deviations in Z-deformation were attributed to material and manufacturing factors. This research highlights the critical role of fiber orientation in achieving desired deformations in SMA-integrated composites, offering valuable insights for the design of adaptive structures. The findings demonstrate the potential for optimizing fiber configurations to tailor bend-twist coupling in advanced composite applications.
Fabrication and characterization of PEGylated magnetite nanoparticles for sustained curcumin release: in-vitro study
Authors: Khan Basharat , Nawaz Mohsan , Waseem Muhammad , Shahzad Nasir , Alsaiari Ahad Amer , Razzokov Jamoliddin , Haq Sirajul
Published: October 2024

A novel approach was adopted to synthesize size-controlled magnetite nanoparticles (MNPs) coated with different molecular weights of polyethylene glycol (PEG), like PEG 750, PEG 2000, and PEG 5000. The drug release kinetics of curcumin (CPMNPs) loaded PEGylated samples were studied. Different techniques used to characterize nanoparticles, like transmission electron microscopy (TEM), x-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). The in-vitro studies of curcumin from CPMNPs samples observed a sustained release through kinetics studies from the PMNPs that followed a pseudo-second order reaction. MNPs functionalized with different molecular weights of PEG to make the MNPS biocompatible; moreover, the role of PEG on sustained release of curcumin was also investigated. It was concluded that the particles synthesized at pH-10 coated with PEG of molecular weight 750 exhibited the highest sustained release efficiency of curcumin, i.e., about 98.8%.
Radiative recombination model for BiSeI microcrystals: unveiling deep defects through photoluminescence
Authors: Dolcet Sadurni Marc , Krustok Jüri , Timmo Kristi , Mikli Valdek , Kondrotas Rokas , Grossberg-Kuusk Maarja , Kauk-Kuusik Marit
Published: October 2024

Pnictogen chalcohalides are semiconductors that have emerged as promising materials for energy conversion due to their exceptional optoelectronic properties. Their electronic configuration (ns2), particularly for Bi- and Sb-based compounds, can be a key factor in efficient carrier transport and defect tolerance, similarly, to Pb-perovskites. In the present study, the Bi-containing chalcohalide, bismuth selenoiodide (BiSeI) was synthesized via isothermal heat treatment of binary precursors in evacuated quartz ampoules. The synthesized BiSeI microcrystals exhibited a characteristic needle-like morphology and a near-stoichiometric composition. Both indirect and direct band gap energies of BiSeI were determined by ultraviolet–visible–near-infrared diffuse reflectance spectroscopy, with room temperature values of 1.17 eV and 1.29 eV, respectively. This study presents the first experimental investigation of the photoluminescence properties of BiSeI microcrystals resulting in a recombination model involving multiple defect states. This work provides valuable insights into the defect structure and recombination mechanisms within BiSeI, paving the way for further exploration of its potential in optoelectronic devices.
Investigating the laser power and trajectory effect on milled surface quality during SiC ceramic processing
Authors: Li Xiaohui , Ding Xin , Gao Haixin
Published: October 2024

Silicon carbide (SiC) ceramics are widely used in industrial production due to their high strength, excellent wear resistance, and superior thermal stability. However, the hard and brittle nature of SiC ceramics presents challenges, such as high processing difficulty, low processing efficiency, and significant tool wear. In this study, we propose a method to enhance the processing efficiency and quality of SiC ceramics by optimizing the machining paths using laser precision milling technology. By adjusting the interlayer laser trajectory angle in multi-layer milling, we were able to control the machining depth and quality of the SiC ceramics. The results show that altering the interlayer laser trajectory angle between adjacent milling layers can significantly impact the milling depth and surface roughness. Additionally, within the laser power range of 4–10 W used in the study, the average milling depth increased as laser power increased. The surface processed with 10 W laser power and a 45° laser trajectory angle exhibited the best surface quality. This research provides valuable data and references for the efficient and high-quality processing of SiC ceramics.
Persistent Mayer Dirac
Authors: Suwayyid Faisal , Wei Guo-Wei
Published: October 2024

Topological data analysis (TDA) has made significant progress in developing a new class of fundamental operators known as the Dirac operator, particularly in topological signals and molecular representations. However, the current approaches being used are based on the classical case of chain complexes. The present study establishes Mayer Dirac operators based on N-chain complexes. These operators interconnect an alternating sequence of Mayer Laplacian operators, providing a generalization of the classical result

D
2

=
L

. Furthermore, the research presents an explicit formulation of the Laplacian for N-chain complexes induced by vertex sequences on a finite set. Weighted versions of Mayer Laplacian and Dirac operators are introduced to expand the scope and improve applicability, showcasing their effectiveness in capturing physical attributes in various practical scenarios. The study presents a generalized version for factorizing Laplacian operators as an operator’s product and its ‘adjoint’. Additionally, the proposed persistent Mayer Dirac operators and extensions are applied to biological and chemical domains, particularly in the analysis of molecular structures. The study also highlights the potential applications of persistent Mayer Dirac operators in data science.
Noise-resilient designs and analysis for optical neural networks
Authors: Kosmella Gianluca , Stabile Ripalta , Sanders Jaron
Published: October 2024

All analog signal processing is fundamentally subject to noise, and this is also the case in next generation implementations of optical neural networks (ONNs). Therefore, we propose the first hardware-based approach to mitigate noise in ONNs. A tree-like and an accordion-like design are constructed from a given NN that one wishes to implement. Both designs have the capability that the resulting ONNs gives outputs close to the desired solution. To establish the latter, we analyze the designs mathematically. Specifically, we investigate a probabilistic framework for the tree-like design that establishes the correctness of the design, i.e. for any feed-forward NN with Lipschitz continuous activation functions, an ONN can be constructed that produces output arbitrarily close to the original. ONNs constructed with the tree-like design thus also inherit the universal approximation property of NNs. For the accordion-like design, we restrict the analysis to NNs with linear activation functions and characterize the ONNs’ output distribution using exact formulas. Finally, we report on numerical experiments with LeNet ONNs that give insight into the number of components required in these designs for certain accuracy gains. The results indicate that adding just a few components and/or adding them only in the first (few) layers in the manner of either design can already be expected to increase the accuracy of ONNs considerably. To illustrate the effect we point to a specific simulation of a LeNet implementation, in which adding one copy of the layers components in each layer reduces the mean-squared error (MSE) by 59.1% for the tree-like design and by 51.5% for the accordion-like design. In this scenario, the gap in accuracy of prediction between the noiseless NN and the ONNs reduces even more: 93.3% for the tree-like design and 80% for the accordion-like design.
Transitioning to building integration of photovoltaics and greenery (BIPVGREEN): case studies up-scaling from cities informal settlements
Authors: Karamanis Dimitrios , Liu Hai-Ying , Skandalos Nikolaos , Makis Achilleas , Kapsalis Vasileios , D’Agostino Delia , Maduta Carmen , Tolis Athanasios , Trandafir Simona , Parker Danny
Published: October 2024

To achieve the objectives of COP28 for transitioning away from fossil fuels and phasing these out, both natural and technological solutions are essential, necessitating a step-change in how we implement social innovation. Given the significant CO2 emissions produced by the building sector, there is an urgent need for a transformative shift towards a net-zero building stock by mid-century. This transition to zero-energy and zero-emission buildings is difficult due to complex processes and substantial costs. Building integrated photovoltaics (BIPV) offers a promising solution due to the benefits of enhanced energy efficiency and electricity production. The availability of roof and façade space in offices and other types of buildings, especially in large cities, permits photovoltaic integration in both opaque and transparent surfaces. This study investigates the synergistic relationship between solar conversion technologies and nature-based components. Through a meta-analysis of peer-reviewed literature and critical assessment, effective BIPVs with greenery (BIPVGREEN) combinations suitable for various climatic zones are identified. The results highlight the multi-faceted benefits of this integration across a range of techno-economic and social criteria and underscore the feasibility of up-scaling these solutions for broader deployment. Applying a SWOT analysis approach, the internal strengths and weaknesses, as well as the external opportunities and threats for BIPVGREEN deployment, are investigated. The analysis reveals key drivers of synergistic effects and multi-benefits, while also addressing the challenges associated with optimizing performance and reducing investment costs. The strengths of BIPVGREEN in terms of energy efficiency and sustainable decarbonization, along with its potential to mitigate urban and climate temperature increases, enhance its relevance to the built environment, especially for informal settlements. The significance of prioritizing this BIPVGREEN climate mitigation action in low-income vulnerable regions and informal settlements is crucial through the minimum tax financing worldwide and citizen’s engagement in architectural BIPVGREEN co-integration.
Multiscale estimates for the condition number of non-harmonic Fourier matrices
Authors: Li Weilin
Published: October 2024

This paper studies the extreme singular values of non-harmonic Fourier matrices. Such a matrix of size

m
×
s

m\times s

can be written as
\[

Φ
=
[

e

−
2
π
i
j

x
k

]

j
=
0
,
1
,
…
,
m
−
1
,
k
=
1
,
2
,
…
,
s

\Phi =[ e^{-2\pi i j x_k}]_{j=0,1,\dots ,m-1, k=1,2,\dots ,s}

\]
for some set

X

=
{

x
k

}

k
=
1

s

\mathcal {X}=\{x_k\}_{k=1}^s

. Its condition number controls the stability of inversion, which is of great importance to super-resolution and non-uniform Fourier transforms. Under the assumption

m
≥
6
s

m\geq 6s

and without any restrictions on

X

\mathcal {X}

, the main theorems provide explicit lower bounds for the smallest singular value

σ
s

(
Φ
)

\sigma _s(\Phi )

in terms of distances between elements in

X

\mathcal {X}

. More specifically, distances exceeding an appropriate scale

τ
\tau

have modest influence on

σ
s

(
Φ
)

\sigma _s(\Phi )

, while the product of distances that are less than

τ
\tau

dominates the behavior of

σ
s

(
Φ
)

\sigma _s(\Phi )

. These estimates reveal how the multiscale structure of

X

\mathcal {X}

affects the condition number of Fourier matrices. Theoretical and numerical comparisons indicate that the main theorems significantly improve upon classical bounds and recover the same rate for special cases but with relaxed assumptions.
An interpolation approach to 𝐿^{∞} a priori estimates for elliptic problems with nonlinearity on the boundary
Authors: Chhetri Maya , Mavinga Nsoki , Pardo Rosa
Published: October 2024

We establish an explicit

L
∞

(
Ω
)

L^\infty (\Omega )

a priori estimate for weak solutions to subcritical elliptic problems with nonlinearity on the boundary, in terms of the powers of their

H
1

(
Ω
)

H^1(\Omega )

norms. To prove our result, we combine in a novel way Moser type estimates together with elliptic regularity and Gagliardo–Nirenberg interpolation inequality. We illustrate our result with an application to subcritical problems satisfying Ambrosetti-Rabinowitz condition.
Uniform convergence for problems with perforation along a given manifold and with a nonlinear Robin condition on the boundaries of cavities
Authors: Borisov D. , Mukhametrakhimova A. R.
Published: October 2024

A boundary value problem is treated for a second order elliptic equation with variable coefficients in a multidimensional domain perforated by small cavities closely spaced along a given manifold. The sizes of the cavities are assumed to be of the same smallness order, while their shapes and the distribution along the manifold are arbitrary. A nonlinear Robin condition is imposed on the boundaries of the cavities. It is proved that the solution of the perturbed problem converges to that of the homogenized problem in the

L
2

L_2

- and

W
2
1

W_2^1

-norms uniformly with respect to the

L
2

L_2

-norm of the right-hand side of the equation. Estimates of the convergence rates are also obtained.
Contractibility of the Rips complexes of Integer lattices via local domination
Authors: Virk Žiga
Published: October 2024

We prove that for each positive integer

n
n

, the Rips complexes of the

n
n

-dimensional integer lattice in the

d
1

d_1

metric (i.e., the Manhattan metric, also called the natural word metric in the Cayley graph) are contractible at scales above

n
2

(
2
n
−
1
)

n^2(2n-1)

, with the bounds arising from the Jung constants. We introduce a new concept of locally dominated vertices in a simplicial complex, upon which our proof strategy is based. This allows us to deduce the contractibility of the Rips complexes from a local geometric condition called local crushing. In the case of the integer lattices in dimension

n
n

and a fixed scale

r
r

, this condition entails the comparison of finitely many distances to conclude that the corresponding Rips complex is contractible. In particular, we are able to verify that for

n
=
1
,
2
,
3

n=1,2,3

, the Rips complex of the

n
n

-dimensional integer lattice at scale greater or equal to

n
n

is contractible. We conjecture that the same proof strategy can be used to extend this result to all dimensions

n
n

.
Convergence from the discrete to the continuous non-linear Fourier transform
Authors: Zhang Ashley
Published: October 2024

In this note, we study the convergence from the discrete to the continuous non-linear Fourier transform. Relations between spectral problems and questions in complex function theory provide a new approach to the study of scattering problems and the non-linear Fourier transform (see A. Poltoratski [Ann. of Math. (2) 199 (2024), pp. 741–793]). In particular, the non-linear Fourier transform can be viewed from the perspective of spectral problems for differential operators. Results of Makarov and Poltoratski [J. Lond. Math. Soc. 108 (2023), pp. 916–977] and Poltoratski and Zhang [J. Funct. Ana. 284 (2023), 29 pp.] can be seen as results for the non-linear Fourier transform. These results are similar to some convergence problems for the discrete non-linear Fourier transform considered by Tao [An introduction to the nonlinear Fourier transform, 2002] and Tao and Thiele [Nonlinear Fourier analysis, 2012].
Strong mixing for the periodic Lorentz gas flow with infinite horizon
Authors: Pène Françoise , Terhesiu Dalia
Published: October 2024

We establish strong mixing for the

Z

d

\mathbb Z^d

-periodic, infinite horizon, Lorentz gas flow for continuous observables with compact support. The essential feature of this natural class of observables is that their support may contain points with infinite free flights. Dealing with such a class of functions is a serious challenge and there is no analogue of it in the finite horizon case. The mixing result for the aforementioned class of functions is obtained via new results: (1) mixing for continuous observables with compact support consisting of configurations at a bounded time from the closest collision; (2) a tightness-type result that allows us to control the configurations with long free flights. To prove (1), we establish a mixing local limit theorem for the Sinai billiard flow with infinite horizon, previously an open question. As far as we know, our approach to the tightness result has no analogue in the literature.
A type 𝐼𝐼𝐼₁ factor with the smallest outer automorphism group
Authors: Chakraborty Soham
Published: October 2024

The canonical modular homomorphism provides an embedding of

R

\mathbb {R}

into the outer automorphism group

O
u
t
(
M
)

Out(M)

of any type

I
I
I

1

\mathrm {III}_{1}

factor

M
M

. We provide an explicit construction of a full factor of type

I
I
I

1

\mathrm {III}_{1}

with separable predual such that the outer automorphism group is minimal, i.e. this embedding is an isomorphism and a homeomorphism. We obtain such a

I
I
I

1

\mathrm {III}_{1}

factor by using an amalgamated free product construction.
Large unions of generalized integral sections on elliptic surfaces
Authors: Phung Xuan Kien
Published: October 2024

Let

f
:
X
→
B

f \colon X \to B

be a nonisotrivial complex elliptic surface and let

D

⊂
X

\mathcal {D} \subset X

be an integral divisor dominating

B
B

. We study finiteness related properties of generalized

(
S
,

D

)

(S, \mathcal {D})

-integral sections

σ
:
B
→
X

\sigma \colon B \to X

of

X
X

where

S
⊂
B

S \subset B

is arbitrary. These integral sections

σ
\sigma

are algebraic and satisfy the geometric condition

f
(
σ
(
B
)
∩

D

)
⊂
S

f ( \sigma (B) \cap \mathcal {D})\subset S

. For

S
⊂
B

S \subset B

finite, the set of

(
S
,

D

)

(S, \mathcal {D})

-integral sections of

X
X

is finite by the well-known Siegel theorem. In this article, we establish a general quantitative finiteness result for large unions of

(
S
,

D

)

(S, \mathcal {D})

-integral sections in which both the subset

S
S

and the divisor

D

\mathcal {D}

are allowed to vary in families where notably

S
S

is not necessarily finite or countable. Some applications to generalized unit equations over function fields are also obtained.
Lie theoretic approach to unitary groups of 𝐶*-algebras
Authors: Ando Hiroshi , Doucha Michal
Published: October 2024

Following Robert’s [J. Reine Angew. Math. 756 (2019), pp. 285–319], we study the structure of unitary groups and groups of approximately inner automorphisms of unital

C
∗

C^*

-algebras, taking advantage of the former being Banach-Lie groups. For a given unital

C
∗

C^*

-algebra

A
A

, we provide a description of the closed normal subgroup structure of the connected component of the identity of the unitary group, denoted by

U
A

U_A

, resp. of the subgroup of approximately inner automorphisms induced by the connected component of the identity of the unitary group, denoted by

V
A

V_A

, in terms of perfect ideals, i.e. ideals admitting no characters. When the unital algebra is locally AF, we show that there is a one-to-one correspondence between closed normal subgroups of

V
A

V_A

and perfect ideals of the algebra, which can be in the separable case conveniently described using Bratteli diagrams; in particular showing that every closed normal subgroup of

V
A

V_A

is perfect. We also characterize unital

C
∗

C^*

-algebras

A
A

such that

U
A

U_A

, resp.

V
A

V_A

are topologically simple, generalizing the main results of Robert [J. Reine Angew. Math. 756 (2019), pp. 285–319] from \cite{Rob19}. In the other way round, under certain conditions, we characterize simplicity of the algebra in terms of the structure of the unitary group. This in particular applies to reduced group

C
∗

C^*

-algebras of discrete groups and we show that when

A
A

is a reduced group

C
∗

C^*

-algebra of a non-amenable countable discrete group, then

A
A

is simple if and only if

U
A

/

T

U_A/\mathbb {T}

is topologically simple.
Care trajectories and transitions at the end of life: a population-based cohort study
Authors: Dufour Isabelle , Courteau Josiane , Legault Véronique , Godard-Sebillotte Claire , Roberge Pasquale , Hudon Catherine ,   the TorSaDE Cohort Working Group, Vanasse Alain , Lebel Alexandre , Quesnel-Vallée Amélie , Lacasse Anaïs , Néron André , Cloutier Anne-Marie , Giguère Annie , Lamarche Benoit , Vissandjee Bilkis , Hudon Catherine , St-Laurent Danielle , Buckeridge David , Roy Denis , Landry Geneviève , Bartlett Gillian , Blanchet Guillaume , Nguena Nguefack Hermine Lore , Leroux Isabelle , Borja Jaime , Ethier Jean-François , Courteau Josiane , Blais Lucie , Choinière Manon , Dorais Marc , Blanchette Marc-André , Côté-Marcil Marc-Antoine , Fleury Marie-Josée , Pomey Marie-Pascale , Benigeri Mike , Courteau Mireille , Sourial Nadia , Roberge Pasquale , Tremblay Pier , Cambon Pierre , Dault Roxanne , Jean Sonia , Quirion Sonia , Plante Stéphanie , Poder Thomas , Émond Valérie
Published: October 2024

Background

End-of-life periods are often characterised by suboptimal healthcare use (HCU) patterns in persons aged 65 years and older, with negative effects on health and quality of life. Understanding care trajectories (CTs) and transitions in this period can highlight potential areas of improvement, a subject yet only little studied.

Objective

To propose a typology of CTs, including care transitions, for older individuals in the 2 years preceding death.

Design

Retrospective cohort study.

Methods

We used multidimensional state sequence analysis and data from the Care Trajectories—Enriched Data (TorSaDE) cohort, a linkage between a Canadian health survey and Quebec health administrative data.

Results

In total, 2080 decedents were categorised into five CT groups. Group 1 demonstrated low HCU until the last few months, whilst group 2 showed low HCU over the first year, followed by a steady increase. A gradual increase over the 2 years was observed for groups 3 and 4, though more pronounced towards the end for group 3. A persistent high HCU was observed for group 5. Groups 2 and 4 had higher proportions of cancer diagnoses and palliative care, as opposed to comorbidities and dementia for groups 3 and 5. Overall, 68.4% of individuals died in a hospital, whilst 27% received palliative care there. Care transitions increased rapidly towards the end, most notably in the last 2 weeks.

Conclusion

This study provides an understanding of the variability of CTs in the last two years of life, including place of death, a critical step towards quality improvement.
PocketDTA: an advanced multimodal architecture for enhanced prediction of drug−target affinity from 3D structural data of target binding pockets
Authors: Zhao Long , Wang Hongmei , Shi Shaoping
Published: October 2024

Motivation

Accurately predicting the drug−target binding affinity (DTA) is crucial to drug discovery and repurposing. Although deep learning has been widely used in this field, it still faces challenges with insufficient generalization performance, inadequate use of 3D information, and poor interpretability.

Results

To alleviate these problems, we developed the PocketDTA model. This model enhances the generalization performance by pre-trained models ESM-2 and GraphMVP. It ingeniously handles the first 3 (top-3) target binding pockets and drug 3D information through customized GVP-GNN Layers and GraphMVP-Decoder. In addition, it uses a bilinear attention network to enhance interpretability. Comparative analysis with state-of-the-art (SOTA) methods on the optimized Davis and KIBA datasets reveals that the PocketDTA model exhibits significant performance advantages. Further, ablation studies confirm the effectiveness of the model components, whereas cold-start experiments illustrate its robust generalization capabilities. In particular, the PocketDTA model has shown significant advantages in identifying key drug functional groups and amino acid residues via molecular docking and literature validation, highlighting its strong potential for interpretability.

Availability and implementation

Code and data are available at: https://github.com/zhaolongNCU/PocketDTA.
Calculating optic nerve planning organ at risk volume margins for stereotactic radiosurgery using optic nerve motion determined using MRI
Authors: Sabharwal Sagar , Heyes Geoff , Tudor George S J , Flintham Robert , Chavda Swarupsinh , Sanghera Paul
Published: October 2024

Objectives

The combination of sharp dose gradients in stereotactic radiosurgery (SRS) and minute optic nerve motion may significantly increase dose to the optic nerves when treating perioptic lesions. The aim of this study was to calculate optic nerve planning organ at risk volume (PRV) margins for CyberKnife SRS treatment planning.

Methods

MRI scans were taken of 10 healthy volunteers looking left, right, up, down, and straight ahead to measure optic nerve motion. The measured optic nerve motion and the uncertainties in the technical accuracy of CyberKnife were used to calculate optic nerve PRV margins.

Results

Two optic nerve PRV margins were calculated: a non-isotropic margin of mL/R,PRV=3 mm, mSup/Inf,PRV=2 mm, and mAnt/Post,PRV=1 mm which considers the full range of motion measured in a worst case scenario; and an isotropic margin of mPRV=1 mm which considers a scenario where patients are asked to look neutrally during imaging and treatment. Applying these PRVs to 8 historical sphenoid wing meningioma CyberKnife plans showed tolerance levels may be exceeded due to optic nerve motion.

Conclusions

Optic nerve PRV margins may be needed in CyberKnife planning to reduce risk to the optic nerves. The use of a mPRV=1 mm PRV to account for organ motion, along with instructing patients to hold their gaze neutrally during imaging and treatment, may be a suitable organ sparing strategy.

Advances in knowledge

Measured optic nerve motion and the technical accuracy of the CyberKnife system have been used to calculate optic nerve PRV margins.
Boron-bridged bis(tetrathiafulvalene) zwitterionic neutral radical conductors: substituent effects on intramolecular and intermolecular electronic interactions and physical properties
Authors: Sonoda Keita , Shimokawa Sota , Suzuki Shuichi , Kusamoto Tetsuro , Ueda Akira
Published: October 2024

We have recently proposed a new molecular design for neutral radical molecular conductors, based on the chemical composition of D2X-type charge-transfer salts (D = π-electron donor molecule, X = monovalent anion). Namely, we connected two tetrathiafulvalene (TTF)-based π-electron skeletons having a charge of +0.5 via a boron anion B–, to obtain a purely organic zwitterionic neutral radical {[(PDT-TTF-Cat)2]+B–}• that shows unique electronic states and properties in the crystal due to the intramolecular and intermolecular interactions of the +0.5-charged π-skeletons. In order to further explore the structural and electronic features of this kind of zwitterionic neutral radical conductor, in this study, we have examined chemical modifications to {[(PDT-TTF-Cat)2]+B–}•. As a result, an analog molecule {[(BMT-TTF-Cat)2]+B–}•, in which propylenedithio (PDT) groups on the TTF terminals in {[(PDT-TTF-Cat)2]+B–}• are replaced by bis(methylthio) ones, was successfully synthesized as air-stable single crystals. Interestingly, this chemical modification causes intramolecular charge disproportionation between the two TTF-based π-skeletons (i.e. the monovalent cation radical TTF+• and the neutral TTF0) coupled to the modulation of the intermolecular distances and interactions between these π-skeletons, leading to electrical and magnetic properties significantly different from those of the crystal of {[(PDT-TTF-Cat)2]+B–}•.