bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigating rotating black holes in bumblebee gravity: insights from EHT observations
Authors: Islam Shafqat Ul , Ghosh Sushant G. , Maharaj Sunil D. 
Published: December 2024

Abstract
The EHT observation revealed event horizon-scale images of the supermassive black holes Sgr A* and M87* and these results are consistent with the shadow of a Kerr black hole as predicted by general relativity. However, Kerr-like rotating black holes in modified gravity theories can not ruled out, as they provide a crucial testing ground for these theories through EHT observations. It motivates us to investigate the bumblebee theory, a vector-tensor extension of the Einstein-Maxwell theory that permits spontaneous symmetry breaking, resulting in the field acquiring a vacuum expectation value and introducing Lorentz violation. We present rotating black holes within this bumblebee gravity model, which includes an additional parameter ℓ alongside the mass M and spin parameter a — namely RBHBG. Unlike the Kerr black hole, an extremal RBHBG, for ℓ < 0, refers to a black hole with angular momentum a > M. We derive an analytical formula necessary for the shadow of our rotating black holes, then visualize them with varying parameters a and ℓ, and also estimate the black hole parameters using shadow observables viz. shadow radius Rs
, distortion δs
, shadow area A and oblateness D using two well-known techniques. We find that ℓ incrementally increases the shadow size and causes more significant deformation while decreasing the event horizon area. Remarkably, an increase in ℓ enlarges the shadow radius irrespective of spin or inclination angle θ
0.
Coherence revival under the Unruh effect and its metrological advantage
Authors: Wang Jiafan , Zhang Jing-Jun , Feng Jun 
Published: December 2024

Abstract
In this paper, we investigate the quantum coherence extraction between two accelerating Unruh–DeWitt detectors, coupling to a scalar field in (3 + 1)-dimensional Minkowski spacetime. We find that quantum coherence as a nonclassical correlation can be generated through the Markovian evolution of the detector system, just like quantum entanglement. However, with growing Unruh temperature, in contrast to monotonously degrading entanglement, we find that quantum coherence exhibits a striking revival phenomenon. For certain detectors’ initial state choices, the coherence measure will reduce to zero at first and then grow to an asymptotic value. We verify such coherence revival by inspecting its metrological advantage on the quantum Fisher information (QFI) enhancement. Since the maximal QFI bounds the accuracy of quantum parameter estimation, we conclude that the extracted coherence can be utilized as a physical resource in quantum metrology.
Gyrokinetic simulations of the effects of magnetic islands on microturbulence in KSTAR
Authors: Wei Xishuo , Nicolau Javier H , Choi Gyungjin , Lin Zhihong , Yang Seong-Moo , Kim SangKyeun , Lee WooChang , Zhao Chen , Cote Tyler , Park JongKyu , Orlov Dmitri 
Published: December 2024

Abstract
Gyrokinetic simulations are utilized to study effects of magnetic islands (MIs) on the ion temperature gradient (ITG) turbulence in the KSTAR tokamak with resonant magnetic perturbations. Simulations show that the transport is controlled by the nonlinear interactions between the ITG turbulence and self-generated vortex flows and zonal flows, leading to an anisotropic structure of fluctuation and transport on the poloidal plane and in the toroidal direction. MIs greatly enhance turbulent transport of both particle and heat. The turbulent transport exhibits variations in the toroidal direction, with transport through the resonant layer near the island X-point being enhanced when the X-point is located at the outer mid-plane. A quantitative agreement is shown between simulations and KSTAR experiments in terms of time frequency and perpendicular wavevector spectrum.
Design and optimization analysis of key parameters for a compact ion source for BNCT
Authors: Yang Yang , Wang Guan , Zhou Wenming , Su Xingkang , Gu Long , Yun Di 
Published: December 2024

Abstract
The 2.45 GHz Electron Cyclotron Resonance Ion Source
(ECRIS) is widely recognized as an effective device for producing
high-intensity H+, H2
+, and H3
+ beams. In
medical cyclotron applications, ion sources are required to be
compact and highly adjustable. A compact design not only reduces the
equipment size, facilitating integration and installation, but also
enhances system stability and reliability. High precision in
adjustment ensures the quality and stability of the ion beam,
meeting the stringent requirements of medical treatments. Therefore,
designing a high-performance compact ECR ion source is crucial for
improving the performance and efficiency of medical cyclotrons. In
this study, we designed an ECR ion source with a discharge chamber
radius of only 25 mm and investigated its plasma formation using a
three-dimensional model. We explored the effects of different
microwave window positions on the extracted beam current,
calculated, and determined the optimal position. Additionally, we
studied the variations in the fractions of H+, H2
+, and H3
+ ions in the chamber with respect to pressure and
microwave power, and discussed the plasma processes within the ECR
ion source chamber based on these findings.
Optimization of LYSO crystals and SiPM parameters for the CMS MIP timing detector
Authors: Addesa F. , Anderson T. , Barria P. , Basile C. , Benaglia A. , Bertoni R. , Bethani A. , Bianco R. , Bornheim A. , Boldrini G. , Boletti A. , Bulla A. , Campana M. , Cardwell B. , Carniti P. , Cetorelli F. , De Guio F. , De Leo K. , De Riggi F. , Dervan J. , Fernandez E. , Gaile A. , Gallinaro M. , Ghezzi A. , Gotti C. , Goldouzian R. , Guglielmi V. , Heering A. , Hu Z. , Jose M. , Karneyeu A. , Krishna A. , Kronheim B. , Kuo C. , La Torre A. , Li A. , Lombardi F. , Lucchini M.T. , Malberti M. , Mao Y. , Marzocchi B. , Meridiani P. , Musienko Y. , Neu C. , Organtini G. , Orimoto T. , Palmer C. , Paganoni M. , Palluotto S. , Paramatti R. , Pessina G. , Perelman R.T. , Quaranta C. , Redaelli N. , Redaelli S. , Reales Gutiérrez G. , Ronchi S. , Santanastasio F. , Schmidt I. , Silva J.C. , Sorrentino G. , Sun X. , Tabarelli de Fatis T. , Tosi M. , Ujvari B. , Varela J. , Wang J. , Wayne M. , White S. , Zhang L. , Zhang M. 
Published: December 2024

Abstract
For the High-Luminosity (HL-LHC) phase, the upgrade of the Compact Muon Solenoid (CMS) experiment at CERN will include a novel MIP Timing Detector (MTD).
The central part of MTD, the barrel timing layer (BTL), is designed to provide a measurement of the time of arrival of charged particles with a precision of 30 ps at the beginning of HL-LHC, progressively degrading to 60 ps while operating in an extremely harsh radiation environment for over a decade.

In this paper we present a comparative analysis of the time resolution of BTL module prototypes made of LYSO:Ce crystal bars read out by silicon photo-multipliers (SiPMs).
The timing performance measured in beam test campaigns is presented for prototypes with different construction and operation parameters, such as different SiPM cell sizes (15, 20, 25 and 30 μm), SiPM manufacturers and crystal bar thicknesses. The evolution of time resolution as a function of the irradiation level has been studied using non-irradiated SiPMs as well as SiPMs exposed up to 2 × 1014 neq/cm2 fluence.
The key parameters defining the module time resolution such as SiPM characteristics (gain, photon detection efficiency, radiation induced dark count rate) and crystal properties (light output and dimensions) are discussed.
These results have informed the final choice of the MTD barrel sensor configuration and offer a unique starting point for the design of future large-area scintillator-based timing detectors in either low or high radiation environments.
Optimization of the magnetic field in the SK1000 central region model magnet
Authors: Wang J. , Yao Q.G. , Dou G.L. , Lyu M.B. , Zhao L.X. , Zhang X. , Wei Z. , Sun L.T. , Zhao H.W. 
Published: December 2024

Abstract
This study presents a design scheme for a central region
model magnet, based on a high-intensity compact cyclotron. The
objective is to ensure the long-term stable production of
therapeutic radionuclides such as 211At and
225Ac, while maintaining reasonable construction
and operational costs. In-depth research into the design principles
and core parameters of the CRM (Central Region Model) cyclotron
magnet system, guided by the concept of isochronous magnetic field
design, enabled the optimization of the magnet's dimensions and
magnetic field distribution. The optimization results show that the
magnet system meets the acceleration and focusing requirements of
the particle beam, effectively prevents particles from entering
dangerous resonance regions, and aligns with the theoretical
requirements of isochronous magnetic fields. This method keeps the
error between the calculated magnetic field and the theoretical
design field within 5 Gauss, meeting the expected physical design
standards.
Beam dynamics studies on a specific radio-frequency quadrupole injector for superconducting linacs
Authors: Zhou Bowen 
Published: December 2024

Abstract
Radio-frequency quadrupole (RFQ) linear accelerators are
widely used at the front end of large-scale hadron accelerator
facilities owing to their extraordinary performance of
progressive bunching, high-efficiency acceleration and low
emittance growth. Meanwhile, it is worth noting that RFQ linacs gradually
become the only normal conducting accelerators in modern
continuous-wave high-power superconducting hadron linacs. As a result, high-quality beams at the exit of RFQ linacs with respect to
more strict beam dynamics requirements are demanded, where minimizing the
emittance growth is one of the most critical design
targets. Not only a small rms emittance is required for an easy rms
match to the following superconducting cavities but also a small total
emittance is needed to reduce the beam loss in the superconducting
cavities. In this paper, the design parameters of some typical RFQ injectors for
superconducting linacs worldwide were compared, and the beam
dynamics design of a 162.5 MHz, 2.1 MeV, continuous-wave
RFQ linac was performed. Guided by the design approach
called MEGLET (Minimizing Emittance Growth via Low Emittance
Transfer), the beam dynamics design of the example RFQ injector was
completed with high transmission efficiency, low emittance growth,
and large error tolerance. The design result could be a reference for similar RFQ linacs, and the beam dynamics design approach is useful and applicable for other linacs intended to improve the figures of merit.
Co-producing water service delivery: a scoping review and typology of informal water vending in Sub-Saharan Africa
Authors: Gilson Gina Grace , Garrick Dustin 
Published: December 2024

Abstract
Informal water providers play a critical role in addressing water supply gaps, especially where rapid urbanisation outpaces the expansion of water networks. They are widespread in Sub-Saharan Africa (SSA), where over 80% of workers are informally employed, and approximately 70% of the population lack access to improved drinking water. Amidst lags in progress towards SDG 6.1 of universal and equitable access to safe and affordable drinking water, there has been growing interest in the role of these vendors and how co-production between formal and informal water supply actors might improve outcomes for different types of consumers. However, we know little about the coordination mechanisms in place and how they operate in practice. We conduct a scoping review of empirical research over the last 20 years to develop insights regarding the different types of co-production that may increase water access. We reviewed published sources to develop a better understanding of the water sources and delivery methods of informal water vendors, and the mechanisms of coordination between formal and informal sectors. To supplement the findings, we develop illustrative examples of the evolution and dynamics of different coordination mechanisms. The article shows how formal (often public utilities) and informal (often private and small scale) water providers are co-producing service delivery in SSA, with insights regarding the different coordination mechanisms that might help or hinder efforts to increase water access. We find that enforcement capacity is crucial for effective coordination, which creates a dilemma: many regions most dependent on informal water providers are least capable of monitoring, let alone enforcing rules. Consumers can benefit from coordination mechanisms that require less effort, such as quality testing, technical assistance, and preferential rates for bulk resale. By specifying how the formal and informal sectors are linked, further studies on co-produced water systems can contribute to evidence regarding what coordinated service delivery options might offer short- and medium-term solutions.
Sensitivity of Arctic marine heatwaves to half-a-degree increase in global warming: 10-fold frequency increase and 15-fold extreme intensity likelihood
Authors: León-FonFay Dalena , Barkhordarian Armineh , Feser Frauke , Baehr Johanna 
Published: December 2024

Abstract
We utilize the 50-member MPI-ESM-LR Earth System model to investigate the projected changes in Arctic marine heatwaves’ (MHWs) characteristics caused by an additional 0.5 ∘C increase in global warming, from 1.5 ∘C to 2 ∘C, with respect to pre-industrial levels. Our results indicate that this 0.5 ∘C increase in global warming triggers an intensified reaction in both the Arctic’s mean sea surface temperature (SST) and variability. In a 2 ∘C warmer world, one out of every four summer months would be warmer than the current climate. We detect a nonlinear increase of MHW intensity in a 2 ∘C world, which is characterized by a break in slope occurring around the year 2042 ± 2 (across 50 ensemble members of the SSP5-8.5 scenario). At the estimated post-break dates, the intensity rate roughly doubles, leading to MHWs in a 2 ∘C world with average cumulative heat intensity 100 ∘C*days higher than in a 1.5 ∘C world. Further results reveal that an extremely rare MHW with an intensity of 3.19 ∘C, classified as a 1-in-100-year event in a 1.5 ∘C world, is expected to transform into a 1-in-7-year event in a 2 ∘C world. This transition signifies a ∼15-fold increase in the likelihood of such events occurring due to a 0.5 ∘C increase in global warming. Likewise, a rare occurrence of years featuring 125 MHW days in a 1.5 ∘C world is projected to become a 1-in-10-year event in a 2 ∘C world, resulting in a 10-fold increase in occurrence probability. The main contributor to these changes is predominantly the rise in mean SST, with enhanced SST variability playing a minor role. These findings highlight that a 2 ∘C world could lead to a substantial escalation of the frequency and intensity of MHWs in the Arctic compared to a 1.5 ∘C world, transforming what are currently rare extreme events into more common events, with significant implications for global climate dynamics and the well-being of Arctic ecosystems and communities.
Current fluctuations in finite-sized one-dimensional non-interacting passive and active systems
Authors: Biswas Arup , Jose Stephy , Pal Arnab , Ramola Kabir 
Published: December 2024

Abstract
We investigate the problem of effusion of particles initially confined in a finite one-dimensional box of size L. We study both passive as well active scenarios, involving non-interacting diffusive particles and run-and-tumble particles (RTPs), respectively. We derive analytic results for the fluctuations in the number of particles exiting the boundaries of the finite confining box. The statistical properties of this quantity crucially depend on how the system is prepared initially. Two common types of averages employed to understand the impact of initial conditions in stochastic systems are annealed and quenched averages. It is well known that for an infinitely extended system, these different initial conditions produce quantitatively different fluctuations, even in the infinite time limit. We demonstrate explicitly that in finite systems, annealed and quenched fluctuations become equal beyond a system-size dependent timescale,

t
∼

L
2

. For diffusing particles, the fluctuations exhibit a

t

growth at short times and decay as

1

/

t

for time scales,

t
≫

L
2

/

D

, where D is the diffusion constant. Meanwhile, for RTPs, the fluctuations grow linearly at short times and then decay as

1

/

t

for time scales,

t
≫

L
2

/

D

eff

, where D
eff represents the effective diffusive constant for RTPs. To study the effect of confinement in detail, we also analyze two different setups (i) with one reflecting boundary and (ii) with both boundaries open.
Scanning probe spectroscopy of sulfur vacancies and MoS2 monolayers in side-contacted van der Waals heterostructures
Authors: Nisi K , Thomas J C , Levashov S , Mitterreiter E , Taniguchi T , Watanabe K , Aloni S , Kuykendall T R , Eichhorn J , Holleitner A W , Weber-Bargioni A , Kastl C 
Published: December 2024

Abstract
We investigate the interplay between vertical tunneling and lateral transport phenomena in electrically contacted van der Waals heterostructures made from monolayer MoS2, hBN, and graphene. We compare data taken by low-temperature scanning tunneling spectroscopy to results from room-temperature conductive atomic force spectroscopy on monolayer MoS2 with sulfur vacancies and with varying hBN layers. We show that for thick hBN barrier layers, where tunneling currents into the conductive substrate are suppressed, a side-contact still enables addressing the defect states in the scanning tunneling microscopy via the lateral current flow. Few-layer hBN realizes an intermediate regime in which the competition between vertical tunneling and lateral transport needs to be considered. The latter is relevant for device structures with both a thin tunneling barrier and a side-contact to the semiconducting layers.
Research status of reversed austenite in martensite: review
Authors: Shao Juhao , Wang Shiqing , Li Fangpo 
Published: December 2024

Abstract
This paper studies the role of reversed austenite in martensitic stainless steels, summarizes the formation principles of reversed austenite in martensitic stainless steels and reviews elements influencing its formation. It also summarizes common heat treatment methods for obtaining reversed austenite in martensitic stainless steels and compares the advantages and disadvantages of various approaches. For example, layered quenching and tempering yield more reversed austenite compared to simple tempering, resulting in finer microstructures at room temperature. The paper analyzes how different reversed austenite contents affect the strength, ductility, and hardness of martensitic stainless steels, as well as the impact on pitting, intergranular, hydrogen, and stress corrosion. It finds that a higher amount of reversed austenite leads to a higher yield-to-tensile strength ratio, increased ductility, and lower hardness. While reversed austenite improves resistance to pitting, intergranular, and stress corrosion, its effect on hydrogen embrittlement remains debated. Additionally, the paper summarizes the formation principles of reversed austenite in martensitic stainless steels and reviews elements influencing its formation, aiming to identify optimal elements and heat treatment methods to increase reversed austenite content. This paper aims to make a summary of the research of experts and scholars in recent years, provide the knowledge foundation for the scholars who have just contacted, and give some reference for the future research direction.
Numerical simulation of heat transfer processes in shell and tube phase change heat exchangers for recovering industrial waste heat
Authors: Ma Guangzeng , Zhang Jing , Wang Jian 
Published: December 2024

Abstract
This article combines phase change energy storage technology with shell and tube heat storage and exchange devices to establish a three-dimensional numerical model of the shell and tube phase change heat storage and exchange device. The hexahedral structured grid division is used to make the simulation results more accurate. Combined with the computational fluid dynamics software Fluent and the related principles of phase change heat transfer, the effects of different heat transfer fluid temperatures and flow rates on the phase change process of phase change materials and the fluid outlet temperature in the phase change heat exchanger were numerically simulated. The results show that under the set parameters, when the inlet water temperature increases from 70 °C to 90 °C, the time required for the outlet temperature to increase from 20 °C to 60 °C is shortened by 23%, while when the temperature is constant, the inlet temperature of heat transfer fluid is shortened by 69%. Analysis shows that the influence of the inlet temperature of the heat transfer fluid on the heat storage and release of phase change materials is significantly greater than the inlet flow rate.
Supercapacitor-based pulse generator with waveform adjustment capability for small animal transcranial magnetic stimulation
Authors: Raju Soniya , Kularatna Nihal , Wilson Marcus , Steyn-Ross D Alistair 
Published: December 2024

Abstract
In transcranial magnetic stimulation (TMS), pulsed magnetic fields are applied to the brain, typically requiring high-power stimulators with high voltages and low series impedance. TMS pulse generators for small animal coils, are underexplored, with limited dedicated circuits and simulation models. Here, we present a new design for a high-power TMS pulse generator for small animals, utilizing a pre-charged supercapacitor that is sufficient to produce repeated pulses for TMS applications without the need for recharging. This approach eliminates the need for expensive high-voltage components and a high-voltage power supply. In this paper, we detail the design approach and basic block diagrams of a supercapacitor (SC) based TMS pulse generator, along with its experimental results. The findings indicate that the new circuit enables a complete test using just a single charge of an SC module. The proposed circuit functions as a versatile pulse-shaping device, where the MOSFET is treated as a dynamically varying resistor element rather than a traditional switch; allowing pulse parameter variations. We analyze a novel circuit for generating and controlling TMS pulses in small animal coils, and demonstrate its effectiveness through experimental results.