bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical reaction simulator on quantum computers by first quantization—Basic treatment: Theoretical
Authors: Tomaru Tatsuya , Takahashi Hideo , Hirano Toshiyuki , Tahara Saisei , Sato Fumitoshi
Published: December 2024

Quantum computers can potentially simulate quantum-mechanical phenomena, so chemical reactions are a potential application of them. In particular, the time evolution of the wavefunctions should be simulated because chemical reactions are accompanied by structural changes. In this study, to pave the way to achieving such wavefunction simulations, we decompose chemical reactions into their main parts and comprehensively show the minimum essential circuits for simulating each part. An antisymmetrized initial state is constructed using ancillae. Chemical reactions should be simulated in two different ways, where the difference is whether the ancillae are released or not. When they are released, the whole electronic system is simulated. When they are not released, orbital information is obtained. These ways are hence complementary.
Generation, migration, and coalescence of droplets: A state-of-the-art review from the perspectives of wettability, inertia, and electric field
Authors: Boruah Manash Protim , Randive Pitambar R. , Pati Sukumar
Published: December 2024

Generation, migration, and coalescence of droplets are some of the fundamental phenomena observed in multiphase microfluidic devices that offer widespread application in interdisciplinary platforms. These phenomena are governed by involved interfacial forces, and tuning these forces through active or passive techniques has emerged as a thriving research domain. Among the available strategies for interfacial force modulation, wettability, electric field, and inertia are some of the key factors that are paid attention as they are largely involved in naturally occurring phenomena and widely applied in technically designed platforms. Motivated by these, this work reviews the studies carried out in the domain of surface wettability and its influence on two-phase flow, to the electrically tuned migration and deformation characteristics of compound drop, and thereafter towards the inertia modulated coalescence dynamics of compound drop, and also explores several unresolved facets that can be addressed by the research community.
Numerical study of plasma and air heating process in single-turn coil discharges
Authors: Ge Aoming , Wang Qiuliang , Li Liang , Lv Yiliang , Peng Tao
Published: December 2024

As a kind of destructive pulsed magnet, single-turn coil generates ultra-high magnetic field beyond 100 T by feeding the Mega-Ampère-level discharge current into a coil with the size of several millimeters. Under the effect of high temperature and high electric field, the air around the coil is ionized and exhibits magnetohydrodynamic characteristics. In this study, a numerical model is built to analyze the air heating and sample thermal destruction. This model uses the collision integral method to calculate the physical parameters of the plasma, and considers not only the heat conduction and convection but also the heat sources of Joule heat, electron-heavy particles collision, work done on air by pressure and pressure change, and air viscous dissipation. The results show that heat conduction and heat convection can only significantly heat the air near the surface of the coil. However, the power density of these two heat sources is greater than the other heat sources, resulting in the highest air temperature near the coil. In addition, Joule heat and electron-heavy particles collision have lower power densities but can heat a larger volume of air outside and inside the coil, respectively.
Estimating surface pressure on flexible structures subjected to flow-induced vibrations
Authors: Anjum M. , Uddin E. , Abdelkefi A.
Published: December 2024

A conventional flag is placed downstream of the inverted half cylinder to study pressure over the flag's surface due to fluid-flexible body interaction between the flag and the vortices generated by the half cylinder. An immersed boundary method provides a reliable and fast solution to the fluid-structure interaction problems, albeit with limitation. One such limitation is the accurate pressure profile over the Lagrangian grid, i.e., the structure boundary. A pressure prediction algorithm is proposed which couples with the improved immersed boundary method to predict pressure over flag's surface. The effect of flow patterns on flag's surface pressure is studied by varying flag's distance from the bluff body. The pressure results are analyzed as negative and positive pressure fluctuations from the assigned reference pressure in the far field. Results show high flag surface pressure at a smaller stream-wise distance. A subsequent decrease in flow pressure is observed, when the stream-wise distance is increased. Changing span-distance shows that the highest pressure occurs at Gy = 0.25 with a significant drop at span positions of 0 and 0.5. The average pressure over the flag's surface is also affected by the vibration modes and the vortex shedding from the surface of the flag. The deflected mode appears at a smaller stream-wise distance accompanied by additional vortex shedding from the flag surface resulting in a high average pressure. Whereas biased and conventional flapping modes appear as stream-wise distance is progressively decreased resulting in reduced average pressure. Hydrodynamic analysis shows that the vortices originating from the bluff body and their subsequent interaction with the flag serve as the primary source of pressure fluctuations resulting in a change in the pressure profile over the surface of the flag.
Numerical investigation of the interaction between a ventilated supercavity and free surface waves at high Froude numbers
Authors: Erfanian Mohammad-Reza , Moltani Ali-Akbar , Pasandidehfard Mahmoud
Published: December 2024

Ventilated supercavitation is a hydrodynamic phenomenon where injected air forms a large bubble around a high-speed submerged body, reducing drag to enhance its movement. The study of cavitating flows is crucial near the free surface due to significant interactions between the supercavity and surface waves. In this study, the behavior of the ventilated supercavity and free surface waves at high Froude numbers and varying submersion depths has been investigated using a numerical simulation approach. The accuracy of the predicted results is verified by comparing them with the available experimental data. The results indicate that the supercavity size is simultaneously affected by submersion depth and Froude number. Additionally, as the Froude number increases, the submersion depth at which the free surface effect on the supercavity shape becomes negligible also increases. Moreover, near the free surface, unlike in fully submerged conditions, the supercavity length increases with depth. The results also show that three types of free surface wave patterns are formed, depending on the intensity of the first and second wave systems.
A simplified prediction model for centrifugal pump side chamber based on the effect of roughness
Authors: Yao Yulong , Wang Chuan , Chen Xionghuan , Wang Hui , Yu Hao
Published: December 2024

Wall roughness in centrifugal pump side chambers significantly affects flow behavior and overall pump performance, yet current research in this area is limited. This study investigates the effects of rough rotor, rough stator, and rough rotor–stator on side chamber flow using numerical simulations and experimental validation. A simplified model is proposed to reduce computational costs, and its accuracy is verified by comparison with a typical centrifugal pump. Using the entropy generation method, the local energy loss and macroscopic fluctuations due to roughness are analyzed. The results show that the effect of rotor roughness plays a dominant role, while the effect of stator face roughness is relatively small. The roughness of the pump chamber walls leads to an increase in centrifugal pump head and a decrease in efficiency. The maximum increase in the centrifugal pump head reaches 1.66% and the maximum decrease in efficiency reaches 1.51% in the studied range. These findings indicate that wall roughness is a key factor in flow losses and potential system instability, with the simplified model offering quick and accurate predictions.
Property optimization of Er/Yb-codoped LiNbO3 crystals for LNOI lasers and amplifiers
Authors: Zhang Zhongzheng , Zhang Yuqi , Wu Zhaojie , Yuan Xin , Liu Shiguo , Liu Hongde , Zheng Dahuai , Kong Yongfa , Xu Jingjun
Published: December 2024

Lithium-niobate-on-insulator (LNOI) is regarded as an ideal platform for integrated photonics. As an essential part, active devices based on rare-earth (RE) doped LNOI have made significant progress, with erbium/ytterbium-codoped lithium niobate (Er/Yb-codoped LN) showing great potential. In this paper, a series of Er/Yb-codoped LN crystals were successfully grown by the Czochralski method, featuring a fixed Er3+ concentration with various Yb3+ doping levels and a fixed RE3+ (RE3+ = Er3+ + Yb3+) concentration. The absorption and emission spectra were measured, and the transfer efficiencies along with relative conversion efficiencies were also displayed. It was concluded that the optimal composition of codoped LN is ∼1.0 mol. % Er3+ and 1.0 mol. % Yb3+, which can enhance active devices by providing lower threshold power, reduced transmission loss, higher transfer efficiency, and improved conversion efficiency. These results will advance the development of high performance LNOI lasers and amplifiers.
Placement poverty has major implications for the future health and education workforce: a cross-sectional survey
Authors: Lambert Kelly , Austin Kylie , Charlton Karen , Heins Rebecca , Kennedy Meredith , Kent Katherine , Lutze Janna , Nicholls Natalie , O’Flynn Gabrielle , Probst Yasmine , Walton Karen , McMahon Anne
Published: December 2024

Objective ‘Placement poverty’ refers to the financial burdens imposed upon students by the completion of mandatory professional placement. We aimed to identify the financial implications of mandatory professional placements on student wellbeing. Methods A cross-sectional online survey (August 2023 to January 2024) completed during students’ most recent professional placement in the final year of their degree. Eligible participants were health or teaching students studying at Australian and New Zealand universities in degrees requiring mandatory professional placement. Questions included total and accommodation costs, financial support, impact of finances on placement preferences, presence of food insecurity, and implications for student wellbeing. Results Participants (n = 530) were mostly health professional (65%) students (median, 25; interquartile range (IQR), 22–30 years, 95.3% domestic, 88.3% full time, 2.0% New Zealand). Health students had higher total costs (in Australian dollars) for the recent placement ($1500; IQR, 600–3453) compared to teaching students ($1200; IQR, 600–2757) (P = 0.02), likely due to longer placement duration (6 weeks for health students). A higher proportion of health students required financial support (P = 0.0001). Placement preferences were always or sometimes (63.8%) determined by cost rather than learning opportunity. Food insecurity was experienced by most students (70.2%) (10.4% marginal, 32.1% moderate, 27.7% severe), with no difference by degree type. Thematic analysis identified themes of burnout, emotional distress, inability to focus on learning, postponing care of oneself, urgent need for financial support, unanticipated family and other circumstances, and worsened societal inequity. Conclusions Our study identified widespread financial difficulty in students undertaking placement that adversely impacted personal wellbeing. Strategies are needed to support wellbeing and ameliorate the financial burden.
Assessing climate-driven glacial retreat, snow-cover reduction and GLOF risks: implications for water resource management amid rising global temperatures and CO2
Authors: Yahya Muhammad , Noreen Uzma , Attia Kotb A. , Jabeen Fariha , Aslam Afifa , Anjum Navid , Abbasi Asim , Zaidi Syed Faizan Hassan
Published: December 2024

Context The consequences of climate change, including alterations in snow and glacier patterns and rising temperatures, pose a risk of glacial lake outburst floods (GLOFs), which can have cross-border impacts, leading to the loss of life and property downstream. Aims This research focused on the assessment of changes in snow cover within Chitral district imposed by temperature increase. Methods ArcGIS and Origin programs were used in this research to study the glacier pattern of Chitral. Results Therer was a significant increase of 266.7% in urban development and an expansion of 135.9 km2 in agricultural areas within this remote mountainous region. The findings of the study show that in the year 2000, >51.6% of Chitral district’s total land was covered by snow during early winter. However, this coverage drastically declined to ~6.8% by 2008. Across the initial two 4-year periods, ~44.7% (5694.6 km2) of the glaciated area transitioned to barren rock, whereas the overall reduction in snow-covered areas accounted for ~43.3% (5514.6 km2). Conclusion Owing to the increasing stress on freshwater resources, it is essential to conduct thorough analyses and monitoring of snow patterns to ensure sustainable freshwater availability and effective environmental risk management. Implications This study emphasises the critical consequences of climate-driven glacial retreat, waning snow cover and increased risks of glacial lake outburst floods (GLOFs) for the management of water resources with the rise in global CO2 and temperatures levels. These changes threaten the timing and availability of water supply, with impacts on agriculture, ecosystem and hydropower. Effective adaptation measures and sustainable management practices are crucial to alleviate these risks and ensure water security in a warming world.
Quantitative imaging of loop extruders rebuilding interphase genome architecture after mitosis
Authors: Brunner Andreas , Morero Natalia Rosalía , Zhang Wanlu , Hossain M. Julius , Lampe Marko , Pflaumer Hannah , Halavatyi Aliaksandr , Peters Jan-Michael , Beckwith Kai S. , Ellenberg Jan
Published: December 2024

How cells establish the interphase genome organization after mitosis is incompletely understood. Using quantitative and super-resolution microscopy, we show that the transition from a Condensin to a Cohesin-based genome organization occurs dynamically over 2 h. While a significant fraction of Condensins remains chromatin-bound until early G1, Cohesin-STAG1 and its boundary factor CTCF are rapidly imported into daughter nuclei in telophase, immediately bind chromosomes as individual complexes, and are sufficient to build the first interphase TAD structures. By contrast, the more abundant Cohesin-STAG2 accumulates on chromosomes only gradually later in G1, is responsible for compaction inside TAD structures, and forms paired complexes upon completed nuclear import. Our quantitative time-resolved mapping of mitotic and interphase loop extruders in single cells reveals that the nested loop architecture formed by the sequential action of two Condensins in mitosis is seamlessly replaced by a less compact but conceptually similar hierarchically nested loop architecture driven by the sequential action of two Cohesins.
Primordial gravitational wave backgrounds from phase transitions with next generation ground based detectors
Authors: Caprini Chiara , Pujolàs Oriol , Quelquejay-Leclere Hippolyte , Rompineve Fabrizio , Steer Danièle A
Published: December 2024

Third generation ground-based gravitational wave (GW) detectors, such as Einstein Telescope and Cosmic Explorer, will operate in the

(
few
−

10
4

)

Hz frequency band, with a boost in sensitivity providing an unprecedented reach into primordial cosmology. Working concurrently with pulsar timing arrays in the nHz band, and LISA in the mHz band, these 3G detectors will be powerful probes of beyond the standard model particle physics on scales

T
≳

10

7

GeV. Here we focus on their ability to probe phase transitions (PTs) in the early Universe. We first overview the landscape of detectors across frequencies, discuss the relevance of astrophysical foregrounds, and provide convenient and up-to-date power-law integrated sensitivity curves for these detectors. We then present the constraints expected from GW observations on first order PTs and on topological defects (strings and domain walls), which may be formed when a symmetry is broken irrespective of the order of the phase transition. These constraints can then be applied to specific models leading to first order PTs and/or topological defects. In particular we discuss the implications for axion models, which solve the strong CP problem by introducing a spontaneously broken Peccei-Quinn (PQ) symmetry. For post-inflationary breaking, the PQ scale must lie in the

10

8

−

10

11

GeV range, and so the signal from a first order PQ PT falls within reach of ground based 3G detectors. A scan in parameter space of signal-to-noise ratio in a representative model reveals their large potential to probe the nature of the PQ transition. Additionally, in heavy axion type models domain walls form, which can lead to a detectable GW background. We discuss their spectrum and summarise the expected constraints on these models from 3G detectors, together with SKA and LISA7

7

Invited review for a CQG Focus Issue on the science case for next generation ground based GW detectors.

.
Truncated amplitude flow with coded diffraction patterns
Authors: Li Huiping , Li Jiayi
Published: December 2024

The phase retrieval problem, which involves Fourier transforms with random masks, has a wide range of applications in signal and image processing, such as diffraction imaging. In recent years, various first-order methods have been explored, including truncated amplitude flow (TAF). These methods are considered to be simple and effective for solving the phase retrieval problem. However, existing convergence results for TAF mainly focus on random Gaussian measurements, which is very far from practical scenarios. In this paper, we analyze the convergence of a revised TAF (RTAF) for the phase retrieval problem. We focus on coded diffraction patterns composed of Fourier transforms and random masks. Then we justify the linear convergence behavior of such algorithm when near the true solution. By utilizing the local initializer found by a non-truncated spectral method, we establish the exact convergence rates in both the noiseless case and the bounded noise case. Further, we have shown that a general signal

x
∈

C

n

can be estimated on an optimal sampling order (specifically,

O
(
n
log
⁡
n
)

). Moreover, our demonstrations indicate that sharp stability can be maintained even when the observations are contaminated by bounded noise. Our experiments have revealed that the RTAF algorithm can reliably estimate the original signal using fewer measurements, aligning with our theoretical analysis. Additionally, numerical experiments have highlighted that the RTAF algorithm outperforms the truncated Wirtinger flow and truncated Riemannian gradient descent algorithms in terms of efficiency and stability, showcasing its superior performance over state-of-the-art algorithms.
Using an electronic balance to measure the kinetic friction coefficient in class experiment
Authors: Luo Duan-bin
Published: December 2024

In this paper, we propose an experimental method for measuring the kinetic friction coefficient using an electronic balance. We measured the kinetic friction coefficient of the wooden block on the paper tape using this method and compared the result with that using the force sensor method. The results of the two methods were in good agreement. This method is convenient and can be implemented in many laboratories, and at the same time it can measure the kinetic friction coefficients between different materials easily. Therefore, it is a simple and practical experimental method for high school students or first-year college students to measure the kinetic friction coefficient in class experiment.
ICRP pregnant-female mesh-type reference computational phantoms part 1: development of fetal phantoms
Authors: Shin Bangho , Kim Suhyeon , Choi Chansoo , Kim Hyeonil , Yeom Yeon Soo , Chung Beom Sun , Nguyen Thang Tat , Moon Sungho , Bolch Wesley E , Kim Chan Hyeong
Published: December 2024

Objective. The International Commission on Radiological Protection (ICRP) decided to develop pregnant-female reference computational phantoms, including the maternal and fetal phantoms, through its 2007 general recommendations. Acknowledging the advantages of the mesh geometry, the ICRP decided to develop the pregnant-female mesh-type reference computational phantoms (MRCPs) for 8, 10, 15, 20, 25, 30, 35, and 38 week fetal ages directly in the mesh format. As part of this process, the present study developed the mesh-type fetal phantoms. Approach. The reference blood-inclusive organ masses, elemental compositions, and densities were established based on various scientific literatures. Then, the phantoms were developed in accordance with the established reference dataset while reflecting the anatomical features of the developing fetus, such as fetal-age-specific anthropometric parameters, bone ossification, and contents formation time. Main results. The phantoms were developed in the tetrahedral-mesh format and can be implemented in the general-purpose Monte Carlo codes (i.e. Geant4, PHITS, MCNP6, and EGSnrc) without the necessity of the voxelization process. To explore the dosimetric impact of the developed phantoms, photon specific absorbed fractions (SAFs) were computed for energies between 10−2–101 MeV for the fetal liver and spleen as source regions and self-irradiation and cross-irradiation to the fetal brain, lungs, and urinary bladder wall as target regions. The SAFs showed the fetal-age-dependent dose trends (i.e. SAF decreases with increasing fetal age) due to organ masses increases via fetal growth. Significance. The mesh-type fetal phantoms, as part of the ICRP pregnant-female MRCPs, will be used to calculate reference dose coefficients for fetal members of the public for both the current and future ICRP general recommendations.
Effect of the cation-to-anion mass ratio of ionic liquid on plume neutralization characteristics for novel electrospray thruster
Authors: Han Meiting , He Jiahui , Meng Baoqing , Tian Baolin , Li Jianling
Published: December 2024

The ionic liquid electrospray thruster (ILET), a promising technology for space electric propulsion, has been gaining attention due to its theoretical capability to operate without an external neutralizer, which is a key component for traditional ion thrusters. Some experiments have shown that the cation-to-anion mass ratio significantly affects the self-neutralization of thruster plumes, but further depth research is still needed. Therefore, numerical simulations of ion emission process both in uni-thruster and bi-thruster modes of ILETs are conducted using particle-in-cell method, to investigate the effect of the cation-to-anion mass ratio in ionic liquid on plume neutralization characteristics. In bi-thruster mode, the anions and cations are emitted simultaneously, while in uni-thruster mode, only anions or cations are emitted under the action of electric field force. Plume neutralization characteristics of four ionic liquid propellants, with different cation-to-anion mass ratio, in bi-thruster mode are obtained and compared to the uni-thruster mode. The results show that the plume profile morphology is significantly dependent on operating mode of the thruster and the cation-to-anion mass ratio of ionic liquid. Unlike the circular profile in uni-thruster mode, the plume in bi-thruster mode exhibit distortion with vertical stratification. The contours of the high-potential region in bi-thruster mode also distort, showing stratification and a V-shape, respectively, influenced by the mass ratio. Ion beam neutralization in bi-thruster mode is primarily achieved through the horizontal displacement of anion and cation beams, as well as their interactions. The cation-to-anion mass ratio influences the oscillation effects of the mass center in anion and cation clouds during neutralization, which in turn affects the neutralization effect. Ionic liquids with a significant mass ratio difference between cations and anions necessitate a longer time and greater distance for neutralization under identical conditions. These findings are instrumental for understanding the plume neutralization process and advancing the design of ILETs.
Searches for exotic spin-dependent interactions with spin sensors
Authors: Jiang Min , Su Haowen , Chen Yifan , Jiao Man , Huang Ying , Wang Yuanhong , Rong Xing , Peng Xinhua , Du Jiangfeng
Published: December 2024

Numerous theories have postulated the existence of exotic spin-dependent interactions beyond the Standard Model of particle physics. Spin-based quantum sensors, which utilize the quantum properties of spins to enhance measurement precision, emerge as powerful tools for probing these exotic interactions. These sensors encompass a wide range of technologies, such as optically pumped magnetometers, atomic comagnetometers, spin masers, nuclear magnetic resonance, spin amplifiers, and nitrogen-vacancy centers. These technologies stand out for their ultrahigh sensitivity, compact tabletop design, and cost-effectiveness, offering complementary approaches to the large-scale particle colliders and astrophysical observations. This article reviews the underlying physical principles of various spin sensors and highlights the recent theoretical and experimental progress in the searches for exotic spin-dependent interactions with these quantum sensors. Investigations covered include the exotic interactions of spins with ultralight dark matter, exotic spin-dependent forces, electric dipole moment, spin-gravity interactions, and among others. Ongoing and forthcoming experiments using advanced spin-based sensors to investigate exotic spin-dependent interactions are discussed.
Database Design for SpExoDisks: A Database and Web Portal for Spectra of Exoplanet-forming Disks
Authors: Wheeler Caleb H. , Hinkel Natalie R. , Banzatti Andrea
Published: December 2024

Data access—or the availability of new and archival data for use by the larger community—is key for scientific advancement. How data is presented, searched, and formatted determines accessibility and it can be difficult to find a solution that fits the needs of a given subdiscipline. We present a generalized roadmap for developing a specialty astronomy database with web application based on the development of the Spectra of Exoplanet-forming Disks (SpExoDisks) database (spexodisks.com), which provides infrared spectra of protoplanetary disks. Expertise in an astronomy subdiscipline can provide two necessary components for creating a database: access to a large volume of specialized data and knowledge of how that data should be presented to the community. However, there are a variety of steps and decisions for database development that can fall outside astronomy expertise. Here we offer generalized discussions on design and process that are accompanied by real-world examples from the SpExoDisks developer team and website. Starting from the database portal design and data organization, we demonstrate on-demand data distribution and query using publicly accessible database software. These systems support interactive visualizations such that users can explore spectra directly from their browsers. We also offer details that show how the technical concepts in SpExoDisks are implemented, particularly emphasizing sustainability and long-term management of the codebase and processes. Finally, we illustrate the utility that a specialty website can offer to the community by providing a specific example of how the combined spectra from SpExoDisks can enhance our understanding of protoplanetary disks.
Algorithms for computing norms and characteristic polynomials on general Drinfeld modules
Authors: Caruso Xavier , Leudière Antoine
Published: December 2024

We provide two families of algorithms to compute characteristic polynomials of endomorphisms and norms of isogenies of Drinfeld modules. Our algorithms work for Drinfeld modules of any rank, defined over any base curve. When the base curve is

P

F

q

1

\mathbb P^1_{{\mathbb {F}_q}}

, we do a thorough study of the complexity, demonstrating that our algorithms are, in many cases, the most asymptotically performant. The first family of algorithms relies on the correspondence between Drinfeld modules and Anderson motives, reducing the computation to linear algebra over a polynomial ring. The second family, available only for the Frobenius endomorphism, is based on a formula expressing the characteristic polynomial of the Frobenius as a reduced norm in a central simple algebra.
Anisotropic overdetermined problem with capillary boundary condition in a half-space
Authors: Guo Jinyu
Published: December 2024

In this paper, we study a Serrin-type anisotropic overdetermined problem with anisotropic capillary boundary in a half-space

R

+

n

\mathbb {R}^{n}_{+}

. We prove that a domain on which this partially anisotropic overdetermined problem admits a solution if and only if the domain is a truncated Wulff ball intersecting

∂

R

+

n

\partial \mathbb {R}^{n}_{+}

with constant anisotropic capillary angle, which generalizes the isotropic results of Jia-Lu-Xia-Zhang [Calc. Var. Partial Differential Equations 63 (2024), 23 pp.].
An improved spectral inequality for sums of eigenfunctions
Authors: Osses Axel , Triki Faouzi
Published: December 2024

We establish a new spectral inequality for the quantified estimation of the

H
s

H^s

-norm,

s
≥
0

s\ge 0

of a finite linear combination of eigenfunctions in a domain in terms of its

H
s

H^s

-norm in a strictly open subset of the whole domain. The corresponding upper bound depends exponentially on the square root of the frequency number associated to the linear combination.
On the regularity of stochastic effective Hamiltonian
Authors: Tu Son , Zhang Jianlu
Published: December 2024

In this paper, we study the regularity of the ergodic constants for the viscous Hamilton–Jacobi equations. We also estimate the convergence rate of the ergodic constant in the vanishing viscosity process.
Non-convergence of some non-commuting double ergodic averages
Authors: Austin Tim
Published: December 2024

Let

S
S

and

T
T

be measure-preserving transformations of a probability space

(
X
,

B

,
μ
)

(X,\mathcal {B},\mu )

. Let

f
f

be a bounded measurable function, and consider the integrals of the corresponding ‘double’ ergodic averages:
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="StartFraction 1 Over n EndFraction sigma-summation Underscript i equals 0 Overscript n minus 1 Endscripts integral f left-parenthesis upper S Superscript i Baseline x right-parenthesis f left-parenthesis upper T Superscript i Baseline x right-parenthesis d mu left-parenthesis x right-parenthesis left-parenthesis n greater-than-or-equal-to 1 right-parenthesis period">

1
n

∑

i
=
0

n
−
1

∫
f
(

S
i

x
)
f
(

T
i

x
)

d
μ
(
x
)

(
n
≥
1
)
.

\frac {1}{n}\sum _{i=0}^{n-1} \int f(S^ix)f(T^ix)\,d\mu (x) \qquad (n\ge 1).

\]
We construct examples for which these integrals do not converge as

n
→
∞

n\to \infty

. These include examples in which

S
S

and

T
T

are rigid, and hence have entropy zero, answering a question of Frantzikinakis and Host.

Our proof begins with a corresponding construction for orthogonal operators on a Hilbert space, and then obtains transformations of a Gaussian measure space from them.
Upper estimates for the Hausdorff dimension of the temporal singular set in chemotaxis-fluid systems
Authors: Fuest Mario
Published: December 2024

The chemotaxis-fluid system
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="StartLayout 1st Row StartLayout Enlarged left-brace 1st Row n Subscript t Baseline plus u dot nabla n equals normal upper Delta n minus nabla dot left-parenthesis n nabla c right-parenthesis comma 2nd Row c Subscript t Baseline plus u dot nabla c equals normal upper Delta c minus n c comma 3rd Row u Subscript t Baseline plus left-parenthesis u dot nabla right-parenthesis u equals normal upper Delta u plus nabla upper P plus n nabla normal upper Phi comma nabla dot u equals 0 comma EndLayout EndLayout">

{

n
t

+
u
⋅
∇
n
=
Δ
n
−
∇
⋅
(
n
∇
c
)
,

c
t

+
u
⋅
∇
c
=
Δ
c
−
n
c
,

u
t

+
(
u
⋅
∇
)
u
=
Δ
u
+
∇
P
+
n
∇
Φ
,

∇
⋅
u
=
0
,

\begin{align*} \begin {cases} n_t + u \cdot \nabla n = \Delta n - \nabla \cdot (n \nabla c), \\ c_t + u \cdot \nabla c = \Delta c - nc, \\ u_t + (u \cdot \nabla ) u = \Delta u + \nabla P + n \nabla \Phi , \quad \nabla \cdot u = 0, \end{cases} \end{align*}

models aerobic bacteria interacting with a fluid via transportation and buoyancy. When posed on a three-dimensional, smoothly bounded, convex domain

Ω
\Omega

, the above equation complemented with suitable initial and boundary conditions is known to admit a global ‘weak energy solution’, which recently has been shown to be smooth (after a redefinition on a set of measure

0
0

) in

Ω
¯

×
E

\overline \Omega \times E

for some countable union of open intervals

E
E

with

|

(
0
,
∞
)
∖
E

|

=
0

|(0, \infty ) \setminus E| = 0

.

The present paper investigates further regularity properties of this solution and proves that (

E
E

can be chosen such that) the

1
2

\frac 12

-dimensional Hausdorff measure of

(
0
,
∞
)
∖
E

(0, \infty ) \setminus E

vanishes and thus that in particular its Hausdorff dimension is at most

1
2

\frac 12

. As

1
2

\frac 12

has been the best known upper estimate for the Hausdorff dimension of the temporal singular set for the unperturbed Navier–Stokes equations for quite some time, this result is the best one can hope for the above system without significant progress in the regularity theory of (homogeneous) Navier–Stokes equations.
Weak compactness in Lipschitz-free spaces over superreflexive spaces
Authors: Silber Zdeněk
Published: December 2024

We show that the Lipschitz-free space

F

(
X
)

\mathcal {F}(X)

over a superreflexive Banach space

X
X

has the property that every weakly precompact subset of

F

(
X
)

\mathcal {F}(X)

is relatively super weakly compact, showing that this space “behaves like

L
1

L_1

” in this context. As consequences we show that

F

(
X
)

\mathcal {F}(X)

enjoys the weak Banach-Saks property and that every subspace of

F

(
X
)

\mathcal {F}(X)

with nontrivial type is superreflexive. It follows from our results that weakly compact subsets of

F

(
X
)

\mathcal {F}(X)

are super weakly compact and hence have many strong properties. To prove the result, we use a modification of the proof of weak sequential completeness of

F

(
X
)

\mathcal {F}(X)

by Kochanek and Pernecká and an appropriate version of compact reduction in the spirit of Aliaga, Noûs, Petitjean and Procházka.
Gabor frame operator for the Cauchy kernel
Authors: Belov Yu
Published: December 2024

New estimates of the upper and lower frame constants for the frame operator

S
=

S

α
,
β

S=S^{\alpha ,\beta }

generated by the Cauchy kernel are found. Also, an explicit formula is provided for the canonical dual window for all rectangular lattices

α

Z

×
β

Z

\alpha \mathbb {Z}\times \beta \mathbb {Z}

,

α
β
≤
1

\alpha \beta \leq 1

.
Q&A Caroline Harper
Authors: Harper C
Published: December 2024

Heading up the science team at a world-class space agency means not only supporting and enabling scientists at the cutting edge, but enthusing and encouraging people of all ages
Dynamic associations between adverse events after lung transplantation and allograft ischaemic time
Authors: Zhang Wenxi , Qiu Tong , Metelmann Isabella B , Fritz Ashley V , Rucker A Justin , Du Wenxing , Sef Davorin , Jiao Wenjie
Published: December 2024

OBJECTIVES

The effect of allograft ischaemic time (AIT) on postoperative events after lung transplantation remains unclear. This study aims to assess the feasibility of extending the duration of AIT.

METHODS

The United Network for Organ Sharing database was queried for adult lung transplantation from 4 May 2005 to 30 June 2020. Patients were divided as per AIT into standard ischaemic time (<6 h) and prolonged ischaemic time (≥6 h) groups using propensity score matching and evaluated on a continuous scale using restricted cubic splines. The primary outcome was overall 1-year and 5-year survival.

RESULTS

Among 11 438 propensity-matched recipients, standard ischaemic time and prolonged ischaemic time showed no differences in overall 1-year (P = 0.29) or 5-year (P = 0.29) survival. Prolonged ischaemic time independently predicted early postoperative ventilator support for >48 h (OR = 1.33, 95% CI 1.22–1.44), dialysis (OR = 1.55, 95% CI 1.30–1.84), primary graft dysfunction (PGD; OR = 1.28, 95% CI 1.09–1.50), acute rejection (OR = 1.42, 95% CI 1.24–1.62), and interestingly, decreased 5-year bronchiolitis obliterans syndrome (HR = 0.91, 95% CI 0.85–0.97). In relative risk curves, 1-year mortality, prolonged ventilation, dialysis and PGD steadily increased per hour as AIT extended. The risk of acute rejection and 5-year bronchiolitis obliterans syndrome also showed significant changes between 5 and 8 h of AIT. In contrast, 5-year mortality remained constant despite rising AIT.

CONCLUSIONS

Prolonged AIT worsened early outcomes such as PGD, but improved bronchiolitis obliterans syndrome freedom at later time points. Despite this, both short- and long-term survival were similar between prolonged ischaemic time and standard ischaemic time patients. Dynamic risk changes in post-transplant events should be noted for prolonged ischaemia lung use.
Artificial intelligence–derived electrocardiographic aging and risk of atrial fibrillation: a multi-national study
Authors: Cho Seunghoon , Eom Sujeong , Kim Daehoon , Kim Tae-Hoon , Uhm Jae-Sun , Pak Hui-Nam , Lee Moon-Hyoung , Yang Pil-Sung , Lee Eunjung , Attia Zachi Itzhak , Friedman Paul Andrew , You Seng Chan , Yu Hee Tae , Joung Boyoung
Published: December 2024

Background and Aims

Artificial intelligence (AI) algorithms in 12-lead electrocardiogram (ECG) provides promising age prediction methods. This study investigated whether the discrepancy between ECG-derived AI-predicted age (AI-ECG age) and chronological age, termed electrocardiographic aging (ECG aging), is associated with atrial fibrillation (AF) risk.

Methods

An AI-ECG age prediction model was developed using a large-scale dataset (1 533 042 ECGs from 689 639 participants) and validated with six independent and multi-national datasets (737 133 ECGs from 330 794 participants). The AI-ECG age gap was calculated across two South Korean cohorts [mean (standard deviation) follow-up: 4.1 (4.3) years for 111 483 participants and 6.1 (3.8) years for 37 517 participants], one UK cohort [3.0 (1.6) years; 40 973 participants], and one US cohort [12.9 (8.6) years; 90 639 participants]. Participants were classified into two groups: normal group (age gap < 7 years) and ECG-aged group (age gap ≥ 7 years). The predictive capability of ECG aging for new- and early-onset AF risk was assessed.

Results

The mean AI-ECG ages were 51.9 (16.2), 47.4 (12.5), 68.4 (7.8), and 56.7 (14.6) years with age gaps of .0 (6.8), −.1 (6.0), 4.7 (8.7), and −1.4 (8.9) years in the two South Korean, UK, and US cohorts, respectively. In the ECG-aged group, increased risks of new-onset AF were observed with hazard ratios (95% confidence intervals) of 2.50 (2.24–2.78), 1.89 (1.46–2.43), 1.90 (1.55–2.33), and 1.76 (1.67–1.86) in the two South Korean, UK, and US cohorts, respectively. For early-onset AF, odds ratios were 2.89 (2.47–3.37), 1.94 (1.39–2.70), 1.58 (1.06–2.35), and 1.79 (1.62–1.97) in these cohorts compared with the normal group.

Conclusions

The AI-derived ECG aging was associated with the risk of new- and early-onset AF, suggesting its potential utility to identify individuals for AF prevention across diverse populations.
Average Age of Resuscitation Blood Products Is not Associated With In-Hospital Mortality Among Trauma Patients: A Retrospective Cohort Study
Authors: Corrigan Kaitlyn T , Skilton Frederick J , Shea Lisa , McHugh Sean P , DeChiara James R , Porter John M , Roberts Brian W , Sarkisian Simon A
Published: December 2024

Introduction

Transfusion of packed red blood cells (PRBC) or low-titer group O whole blood (LTOWB) has become standard practice in trauma patients with significant blood loss. As blood ages, it undergoes metabolic and structural changes. This study aimed to test the association between age of PRBC/LTOWB and mortality among adult trauma patients.

Materials and Methods

This is a retrospective cohort study at an academic level one trauma center. Adult trauma patients who received at least one unit of PRBC or LTOWB within the first hour of arrival to the emergency department (ED) between January 2016 and December 2019 were included. The primary outcome was in-hospital mortality. Multivariable logistic regression models were used to test the associations between the mean age of PRBC and LTOWB units transfused during the initial 24 hours and in-hospital mortality.

Results

Of 388 patients included, 362 received PRBC and 121 received LTOWB. In-hospital mortality occurred in 31% of patients. The median (interquartile range) mean age of transfused PRBC units was 21 (16-26) days and LTOWB units was 11 (9-12) days. Neither age of PRBC nor LTOWB were found to be associated with in-hospital mortality: PRBC adjusted odds ratio (aOR) = 0.99 (95% CI 0.95 to 1.03) and LTOWB aOR = 1.12 (95% CI 0.88 to 1.41).

Conclusions

The mean age of LTOWB or PRBC units transfused during the first 24 hours after presenting to the ED for a traumatic injury was not found to be associated with in-hospital mortality.
Temporal attention amplifies stimulus information in fronto-cingulate cortex at an intermediate processing stage
Authors: Zhu Jiating , Tian Karen J , Carrasco Marisa , Denison Rachel N
Published: December 2024

The human brain faces significant constraints in its ability to process every item in a sequence of stimuli. Voluntary temporal attention can selectively prioritize a task-relevant item over its temporal competitors to alleviate these constraints. However, it remains unclear when and where in the brain selective temporal attention modulates the visual representation of a prioritized item. Here, we manipulated temporal attention to successive stimuli in a two-target temporal cueing task, while controlling for temporal expectation with fully predictable stimulus timing. We used magnetoencephalography and time-resolved decoding to track the spatiotemporal evolution of stimulus representations in human observers. We found that temporal attention enhanced the representation of the first target around 250 ms after target onset, in a contiguous region spanning left frontal cortex and cingulate cortex. The results indicate that voluntary temporal attention recruits cortical regions beyond the ventral stream at an intermediate processing stage to amplify the representation of a target stimulus. This routing of stimulus information to anterior brain regions may provide protection from interference in visual cortex by a subsequent stimulus. Thus, voluntary temporal attention may have distinctive neural mechanisms to support specific demands of the sequential processing of stimuli.
Fusarium boothii, Fusarium meridionale, and Fusarium temperatum Are Emerging Preharvest Maize Ear Rot Pathogens in Ethiopia
Authors: Deressa Temesgen , Adugna Girma , Suresh L. M. , Bekeko Zelalem , Iriarte-Broders Gloria , Vaughan Martha M. , Proctor Robert H. , Mehl Hillary Laureen , Prasanna Boddupalli M. , Opoku Joseph
Published: December 2024

Fusarium ear rot (FER) and Gibberella ear rot (GER) caused by Fusarium species are major diseases affecting maize production in Ethiopia. In addition to reducing quality and yield, these fungi can produce mycotoxins that contaminate maize kernels and, thereby, pose health hazards to humans and livestock. A survey was conducted in 10 administrative zones of Ethiopia within the major maize-growing regions of the country to identify the species of Fusarium associated with ear rot. Twenty kernels were sampled from ears randomly collected from each zone (12 ears per field, 24 fields per zone). Ninety-two fungal isolates recovered from the kernels were tentatively identified as Fusarium based on morphological traits. Subsequently, the species identity of each isolate was determined by DNA sequence analysis of a portion of the translation elongation factor 1-α gene and two noncontiguous fragments of the RNA polymerase II subunit gene. Based on phylogenetic analysis of the data, 37.3% of the isolates recovered from maize kernels were from three species that have not been reported previously in Ethiopia: Fusarium boothii (4.3%), F. meridionale (10.2%), and F. temperatum (22.8%). Completion of Koch’s postulates with selected isolates confirmed that these three species can cause maize ear rot. Information on causal agents of maize ear rots in Ethiopia should be taken into consideration when developing disease management strategies, including breeding for resistance.
Methadone-Buprenorphine Transfers Using Low Dosing of Buprenorphine: An Open-label, Nonrandomized Clinical Trial
Authors: Tremonti Chris , Blogg James , Jamshidi Nazila , Harjanto Ricky , Miles Nicholas , Ismay Charlotte , Page Robert , Mills Llew , Buckley Nicholas , Perananthan Varan , Lintzeris Nicholas , Haber Paul
Published: December 2024

Aims

To compare a low-dosing protocol to standard practice for methadone-buprenorphine transfers.

Methods

We undertook a nonrandomized open-label clinical trial across 8 sites from NSW, Australia. Participants prescribed methadone wishing to transfer to buprenorphine could either choose or be randomized to a low-dose transfer or standard care transfer as per NSW health guidelines. The low-dose protocol started at 0.2 mg BD and increased to 16 mg on day 6, with flexible dosing thereafter. The primary outcome was continuation of buprenorphine 1 week post-transfer. Binary logistic regression was used to access the primary outcome with demographic differences between the groups included as covariates.

Results

There were 117 participants who commenced the study, 101 in the low-dose arm and 16 in standard care. Mean methadone dose was 82 mg in the low-dose arm and 46 mg in standard care. The primary outcome was met by 81 participants in the low-dose arm (80%) and 13 participants in standard care (81%). There was no significant between-arm difference in the odds of the primary outcome (OR = 2.22; 95% CI: 0.45–10.91; P = 0.327). Four participants (4%) in the low-dose arm experienced precipitated withdrawal against 1 (6%) in standard care. Higher methadone dose decreased the odds of successful transfer by 20% (OR = 0.8 per 10 mg methadone; 95% CI: 0.7–0.99; P = 0.04). Withdrawal scores between the 2 arms were similar.

Conclusions

We were unable to detect a difference between low dosing and standard care for methadone to buprenorphine transfers. Increasing methadone dose was a predictor of success; setting (ambulatory or inpatient) was not.